N.E.quest Vol 4 Issue 2 July 2010

Newsletter of North East India Research Forum July 2010

N. E. Quest; Volume 4, Issue 2, July 2010.


N. E. Quest; Volume 4, Issue 2, July 2010.

Newsletter Of

NORTH EAST INDIA RESEARCH FORUM

http://tech.groups.yahoo.com/group/northeast_india_research/ www.neindiaresearch.org

http://www.neindiaresearch.org/


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Green chemistry and a sustainable future At first I would like to thank Dr. Arindam Adhikari and all other group members for giving me the opportunity to write the editorial of North East Quest, July issue. It was at times little depressing when not enough articles were coming in at proper time and the regular time to publish the magazine was going out of hand. But now it is ready in a readable format. My special thanks go to Dr. Bipul Sarma who helped me a lot in collecting the articles from different group members. I am writing this editorial on “Green Chemistry” as the awareness is utmost necessary at this moment for all of us to save the environment for the future in all possible ways. The word “Green Chemistry” relates us to an old existing but newly emerging approach in chemical science which, focuses on following some simple principles that in turn secures a safe and healthy environment for future. The principles mainly focus on the prevention of waste than to treat or clean up waste after it is formed. There are twelve main principles that lead to the science of creating safe, energy efficient and non-toxic products and processes that offers a concrete path towards solving the environmental problems our society faces today. At the time when the whole world has started suffering from the harsh effect of environmental pollution in all possible ways, the practice of green chemistry in every filed including basic science, industry and general life is becoming vastly important.

Many countries around the world have already started programmes in green chemistry in their schools and universities to make more and more people aware of the benefits of green chemistry principles, how they might change the path of environmental degradation towards positive, how they could ensure a safe world for our coming generations. The governments are also allocating lots of funds towards green chemistry research. In the United States, The National Science Foundation and Environmental Protection Agency supports various research programmes and awards to bring more and more scientists and industries in to the field of Green Chemistry. Even the Publishers like American Chemical Society and the Royal Society of Science in Europe are taking much interest in creating awareness amongst the scientific society through their journals, seminars and the awards. In India also, the Department of Science and Technology had established a special task force on green chemistry to promote it during 2003. Many universities, CSIR institutes, and institutes under DST are supporting various projects and program towards creating the awareness in this field. But still we have to go a long way before we could make most of our scientific society and the common people aware of the principles that will hand us a sustainable future for the coming generation. I wish that time will come very soon when we could stop ourselves from destroying our own world anymore.

(Babita Baruwati)


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Table of Contents

1 From the desk of editor 1 2 North east Forum, beginning, growth etc. 3-6 3 A North East India Research Forum Initiative 6-7 4 Members in news, fellowships etc 8 5 Science news 9-10 6 North East Indian made us proud 11

ARTICLE SECTION

7 Mathematics as a career (Shanta Laishram) 12-15 8 Historical Developments and Present Trends of Research in Soft

Magnetic Materials ( M.P.C. Kalita) 16-24

9 Electrocatalysis, Fuel cell, Oxygen reduction reaction, etc. ( Pankaj Bharali)

24-28

10 Stem Cells and Their Potential Applications in Therapeutics (Khirud Gogoi)

28-33

11 Coffee: The most popular beverage (Progyashree Goswami) 34-36 12 Circular Dichroism: An excellent technique for determination of

absolute configuration (Pori Buragohain) 37-39

THESIS SYNOPSIS

13 STRUCTURAL AND THERMAL ANALYSIS OF ORGANIC SOLIDS (Bipul Ch. Sarma)

40-46

14 INVESTIGATIONS ON HIGH DENSITY HOLOGRAPHIC DATA STORAGE AND CONTENT-ADDRESSABLE SEARCH (Bhargab Das)

46-59

INSTRUMENT OF THE ISSUE

15 Small-angle X-ray scattering (SAXS) ( Bipul Ch Sarma) 59-63 16

Letter from Members (Akashi Baruah)

63

17 Members face 64 18 Jobs ,Postdoc, Etc 65-68 19 Details about the NE forum 69 20 End cover


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North East India Research Forum

was created on 13th

November 2004.

1. How we are growing. Every forum has to pass through difficult phases at the time of birth. NE India Research Forum is also no exception. At the very beginning, it was a march hardly with few members (from chemistry only) and today the forum comprised of a force of 350 elite members. Now we are in a position such that people voluntarily come and join the group irrespective of disciplines.

Graph of no of members w.r.t. months

2. Discussions held in the forum • Necessity of directory of all the members of

the forum. • Possibility of organising conference in the

N. E. India. • Taking initiation on setting up of South East

Asian Scientific Institute. • On selection of Best paper award. • Let us introspect. 3. Poll conducted and results • North East India is lacking behind the rest

of the country due to- 1. Geographical constrain = 0% 2. Bad leadership = 40% 3. Lack of work culture = 36% 4. Corruption = 18% 5. Apathy from Central Govt. = 4%

• Which area of science is going to dominate by creating a great impact on society in next decade?

1. Nanoscience & nanotechnology = 22% 2. Biotechnology = 11% 3. Nanobiotechnology = 38% 4. Chemical Engineering = 0% 5. Medicine = 11% 6. Others = 16% 7. None = 0%

• Kindly let us know your view regarding the following topic. What activities of this group you like most?

1. Research articles = 33% 2. Information about vacancy/positions

available = 10% 3. Way to have a contact with all members =

29% 4. Scientific discussions = 14% 5. Others = 2%

• Selection of name for Newsletter There were total 36 proposals submitted by members of the forum for the Newsletter. The name proposed by Mr. Abhishek Choudhury, N.E. QUEST received the maximum number of votes and hence it is accepted as the name of the Newsletter. • How often should we publish our newsletter

'' N. E. Quest’’? 1. Every 3 months = 61% 2. Every 6 months = 38% 3. Once a year = 0%

4. Editors of Previous NE-Quest Issues 1. Vol 1 Issue 1 April, 2007 Editor: Dr. Arindam Adhikari 2. Vol 1 Issue 2 July 2007 Editor: Dr. Tankeswar Nath 3. Vol 1 Issue 3 October 2007 Editor: Dr. Ashim Jyoti Thakur 4. Vol 1 Issue 4 January 2008 Editor: Mr. Pranjal Saikia


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5. Vol 2 Issue 1 April 2008 Editor: Dr. Sasanka Deka 6. Vol 2 Issue 2 July 2008 Editor: Dr. Rashmi Rekha Devi 7. Vol 2 Issue 3 October 2008 Editor: Dr. Prodeep Phukan 8. Vol 2 Issue 4 January 2009 Editor: Dr. Manab Sharma 9. Vol 3 Issue 1 April 2009 Editor: Dr. Debananda Ningthoujam 10. Vol 3 Issue 2 July 2009 Editor: Dr. Robert Singh Thangjam 11. Vol 3 Issue 3 October 2009 Editor:Dr Pankaj Bharali 12. Vol 3 Issue 4 January 2010 Editor: Dr. Abdul Wahab 13. Vol 4 Issue 1 April 2010 Editor: Dr. Utpal Bora 14. Vol 4 Issue 2 July 2010 Editor: Dr. Babita Baruwati 5. A domain in the name of www.

neindiaresearch.org is booked. 6. Future activities Proper planning and consequent implementation always play an important role in every aspect. Some of the topics / activities / suggestions which were being discussed, time to time in the forum will get top priorities in our future activities. Those are mentioned here, • Preparing complete online database of N.E.

researchers with details. • Organising conference in the N.E. region-

proposed by Dr. Utpal Bora. • Research collaboration among forum

members. • Motivate student to opt for science

education. • Help master’s students in doing projects in

different organisation-proposed by Dr. Khirud Gogoi.

• Supporting schools in rural areas by different ways.

• Best paper awards. • Compilation of book on ‘Education system

of different countries’. Initiative for this project is taken by Dr. Mantu Bhuyan, NEIST, Jorhat, Assam

7. New activity • Guidelines for the members are being

formulated by the moderators of the NE India Research Forum. These guidelines are placed in the forum for discussion.

• HimMedia Laboratories Pvt. Ltd is willing to sponsor some future activities of the forum and have asked for space to advertise for their products in the N.E.Quest. Starting the issue (July 2009) N. E. Q. is providing one page for the advertisement. Details about this deal will be informed soon once finalised. Thanks to Dr. Robert Thangjam for his initiative in this matter.

• North East India Research Forum cell has been started in the following university and colleges colleges,

1. Cell in the Dibrugarh University Contact: Dr. Jitu Ranjan Chetia Dept. of Chemistry Email: [email protected] 2. Cell in Tezpur University Contact: Dr. Ashim J. Thakur Dept. of Chemistry Email: [email protected] Phone: +91 (3712) 267008/9/10 extn 5059 3.Cell in Manipur University Contact: Dr. Debananda S. Ningthoujam Coordinator, Microbial Biotech Lab Reader & Head, Dept of Biochemistry, Manipur University, Canchipur, Imphal, India Email: [email protected]

mailto:[email protected]


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4.Cell in Mizoram University Contact: Dr. Thangjam Robert Singh Assistant Professor Department of Biotechnology Mizoram University, Aizawl, India Email: [email protected] Phone: +91 389-2330861/2330859 (O) 5.Cell in Govt. Science College, Jorhat (Jorhat Institute of Technology) Contact: Mr. Prasanta Kumar Bordoloi, Senior Lecturer Email: [email protected] Mobile: +91-9957036339 6.Cell in Arya Vidyapeth College, Guwahati Contact: Mr. Pabitra Kalita, Senior Lecturer Email: [email protected] Mobile No: +91-9613133859 & Dr. Pradip Bhattacharyya, Senior Lecturer Email: [email protected] Mobile No: +91-9864087494 7.Cell in Pandu College, Pandu Contact: Mr. Sanchay Jyoti Bora Lecturer, Department of Chemistry E-mail: [email protected] Mobile: (+91) 9854078814 8.Cell in Bajali college, Pathsala Contact: Mr. Arindam Talukdar, Lecturer, Environment and Tourism Dept. Email: [email protected] &Mr. Satyendra Nath Kalita, Lecturer, Deptt. of Zoology Email: [email protected] To run the forum smoothly, to make it more organised and to speed up activities, formation of a committee/team is essential. The combined discussion of the moderators and senior members make the forum feel the importance of Advisors, co-ordinator, volunteer, webmasters

etc. Of course it needs more discussion and will be approved by poll. 8. Guidelines for the forum The moderators formulated some guidelines for the forum which are as follow. These guidelines were kept open for discussion in the forum. With time and need the guidelines will be changed.

1. Anybody in the forum can start a meaningful and constructive discussion after discussion with moderators.

2. Comments from the individual members do not necessarily reflect the view of the forum.

3. No single moderator can take a crucial decision. All decision would be taken by the moderators unanimously or together with the group as majority.

4. One should not write any massage to the forum addressing some particular members. It should always start with Dear all / Dear esteemed members etc.

5. If one has to write a mail to a particular member she/he should write personal mail.

6. Everyone has the freedom to speak but that doesn’t mean that one should attack personally. Of course we do have differences. There can be debate or discussion, but it should always be a healthy one. One’s personal comment should be written in such a way that it reflects his/her view only. It should not touch other's sentiments/emotions.

7. Whenever we are in a forum, society, home, members should be sensitive / caring enough to their comments so that it does not hurt sentiment of any second members.

8. Members should not post greetings messages (Bihu wish, New Year wish etc) to the forum.


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9. Members should post authentic news only. The source of the news should be authentic. No controversial news or comment should be posted to the forum.

10. Our main aim is to discuss science to generate science consciousness, scientific temperament, sensitivity, awareness and research for the benefit of the mankind in general and North East India in particular.

11. In severe cases, moderators can take a hard decision unanimously or majority wise (may be through poll). (This point needs to be accepted by all the members).

While sending request or while fulfilling request for articles please follow the following points.

• The forum has been formed to help each other. When a member requests articles/literature to forum, members of the forum are always happy to help the person by supplying the articles. But at this stage we have to keep in mind that the article should be sent to the person who requested it, not to the whole forum as it creates lots of unnecessary mails in the message box of the forum. Moreover if it continues, it becomes an irritation also for many members.

• It is also the duty of the person who requests article to acknowledge the person who helped him/her. This can be done by writing ' Request fulfilled by......' in the subject area while composing the mail and write a thanking message in the main message board. Once this is done, then if some other members want to send the article will know about the status of the request.

This will also help members in keeping mailbox clean. For example

• Moreover sending articles (copyright protected articles) to the open forum violates copyright act. So please send the article to the person who requests not to everybody through this open forum.

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A North East India Research Forum

Initiative North East India Research Forum in association with Pragyan- Tinsukia college organized a lecture cum interactive session for young science aspirants on 17th of April 2010 at Tinsukia College, Tinsukia, Assam. Prof. Arvind Anant Natu from Indian Institute for Science Education and Research (IISER)-Pune was invited for the event to talk on ‘ Opportunities in Pure Science’. The main aim of the lecture was to motivate students towards pure science for higher education. It was Dr. Arindam Adhikari, who on his way to his home at Tinsukia from Stockholm met Dr. Arvind Natu in Pune and convinced him to deliver a lecture in Tinsukia on the said topic. After reaching Tinsukia, Dr. Adhikari contacted Mr. Sushanta Kar of Tinsukia college about arranging the lecture. Mr. Kar was excited to know about that and agreed to organize the lecture in Tinsukia College. As it was a festival season, everybody was skeptical about the success of the lecture initially. After several meetings slowly people started coming forward. The duo personally and along with faculty members from Tinsukia college, viz. Mr. Anjan Borthakur, Mrs. Dipika Bhattacharjee visited the schools in Tinsukia to inform about the lecture and invited to take part in the event. The target


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group for the lecture was class 10th, 11th and 12th students along with their parents and teachers. The main aim of the lecture was to motivate students towards pure science for higher education. In the mean time Dr. Adhikari contacted past student of Tinsukia college and one of the members of North East India Research Forum Dr. Mukut Gohain who was working at Univerisided de Bugos, Madrid, Spain and informed him about the event. He helped in getting students from Doomdooma, Philobari and Kajikhowa for the event. The event was presided over by Dr. Bhuban Gogoi, principal of Tinsukia college. From North East India Research Forum, Dr. Adhikari and Dr. Gohain were present on that event. Dr. Adhikari, who was working in the Institute for Surface Chemistry, Stockholm, Sweden introduced himself, Prof. Natu and Dr. Gohain also to the audience. Dr. Adhikari, also briefed the audience about the North East India Research Forum (www.neindiaresearch.org), it’s activities and about it’s online science magazine N. E. Quest. He, in his speech raised the issue ‘Need of Higher Science & Technology institute in and around Tinsukia district‘. He raised the issue why despite having abundant resources in this area, Tinsukia and its adjoining areas still lacks a higher educational institute like university or any scientific research organization which is needed for homogeneous development of the country. Dr. Gohain also expressed in his speech the necessity of such higher educational institute in this most backward part of this country. Prof. Natu delivered an interesting and inspiring lecture on that occasion. He gave many examples of day to day and advanced

technology which has been inspired from nature. He also introduced IISER to the student, its admission process and education system. There was an interesting interactive session afterward. Dr. Adhikari, one of the main initiator of the event and Mr. Dilip Kalita helped the audience by presenting a brief translated Assamese version of the talk. In the event, Dr. Sukhen Chakraborty also expressed his views about the event asked the organizers to organize more such events. Mr. Kar also gave a brief information about organizing the lecture. Many retired and present science teachers of Tinsukia college from various fields were present on that occasion and appreciated this kind of activities. At the end Prof. Natu and the audience appreciated the step taken by North East India Research Forum and urges to take more such activities. Following are the schools participated in the event

1. Chikaragaon Jatiya Bidyalaya, Doomdooma

2. Philobari Jatiya Bidyalaya, Doomdooma

3. Panitola Girls High Schools, Panitola 4. Baruahola High School, Panitola 5. Aniruddha Junior Science College,

Dibrugarh 6. Soumarjyoti, Parbotia, Tinsukia 7. Teg Bahadur, Tinsukia 8. A- New High school, Tinsukia 9. St. Stephens School Tinsukia 10. Senairam H. S. School, Tinsukia 11. Saumar Jyoti Bidyapith, Tinsukia 12. Guru Tegbahadur Sr.Secondery

School, Tinsukia 13. St. Stephen School, Tinsukia 14. Pinwood Junior College, Tinsukia 15. English Academi, Tinsukia 16. A New High School, Tinsukia 17. Jatiyo Bidyalaya, Tinsukia

(http://www.sentinelassam.com/state2/story.php?sec=2&subsec=7&id=39531&dtP=2010-06-22&ppr=1)

http://www.neindiaresearch.org/


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1. Dr. Santa Laishram has joined

Indian Statistical Institute, Delhi as an Assistant professor from July 2010. He was working as an assistant Professor at Indian Institute of Science Education and Research (IISER), Bhopal before joining ISI, Delhi.

2. Dr. Arindam Adhikari has joined as

a scientist in Central Electrochemical Research Institute (CECRI/CSIR) Kadaikudi, Tamilnadu from June 2010.

3. Dr. Kamalesh Prasad, Scientist,

Central salt and Marine Research Institute, Bhavnagar, has been awarded with the CSIR young scientist award in chemical sciences for the year 2010.

4. Mrs. Parasha Hazarika has been awarded Ph.D. degree by Dibrugarh University recently. She did her Ph.D. under the supervision of Dr. Dilip Konwar (Sc. E1) of Synthetic Organic Chemistry Division, NEIST, Jorhat. Her topic of research is “Development of new synthetic reagent systems and synthesis of some drug intermediates: A green approach”. She has published 7 papers in different international journals of repute.

5. Manashjit Gogoi (Research Scholar,

Department of Biosciences and Bioengineering, IIT Bombay), and his team members won the first Prize

in BEST (Biotechnology Entrepreneurship Students' Team). The topic was Novel, cost effective point of care diagnostic system for detection of cancer: A way towards better cancer diagnosis.

6. Dr. Babita Baruwati has been selected to join Hindustan Unilever, Bangalore as a research scientist. She will join the company on 2 nd November 2010. She is presently working as a research associate at United States Environmental Protection Agency, Cincinnati, OH.

7. Dr. Mukut Gohain has joined

Department of Chemistry, University of the Free State, Bloemfontein, Republic of South Africa as post doctoral fellow from July 2010

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In science the credit goes to the man who convinces the world, not the man to whom the idea first occurs. Sir Francis Darwin, Eugenics Review, April 1914

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183 species of butterfly documented in Arunachal

As many as 183 species of butterfly have been identified and photo documented in the buffer area of Namdhapa National Park in Arunachal Pradesh during the 5-day 13th Butterfly India Meet.

Stating this, Ariff Siddiqui, an organiser, said more species would be found in the core area of the park which they could not venture into due to rain. The thirty participants from different parts of the country also identified numerous moths apart from some glittering beetles like 'Golden Tortoise' during the meet which ended on Friday. Dr Alfred, Former Director of the Zoological Survey of India also said, "This is an encouraging indicator for existence of many other species of the butterflies in the core area in Namdhapa and in new forests in the area." Students from five schools in and around Miao town were invited to participate in an awareness programme entitled 'Breakfast with Butterflies'

http://www.expressindia.com/latest-news/183-species-of-butterfly-documented-in-Arunachal/651125

India unveils prototype of $35 tablet computer

It looks like an iPad, only it's 1/14th the cost: India has unveiled the prototype of a $35 basic touchscreen tablet aimed at students, which it hopes to bring into production by 2011. If the government can find a manufacturer, the Linux operating system-based computer would be the latest in a string of "world's cheapest" innovations to hit the market out of India, which is home to the 100,000 rupee ($2,127) compact Nano car, the 749 rupees ($16) water purifier and the $2,000 open-heart surgery. The tablet can be used for functions like word processing, web browsing and video-conferencing. It has a solar power option too - important for India's energy-starved hinterlands - though that add-on costs extra. "This is our answer to MIT's $100 computer," human resource development minister Kapil Sibal told the Economic Times when he unveiled the device on Thursday. In 2005, Nicholas Negroponte - co-founder of the Massachusetts Institute of Technology's Media Lab - unveiled a prototype of a $100 laptop for children in the developing world. India rejected that as too expensive and embarked on a multiyear effort to develop a cheaper option of its own.

http://www.expressindia.com/latest-news/183-species-of-butterfly-documented-in-Arunachal/651125/




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Negroponte's laptop ended up costing about $200, but in May his nonprofit association, One Laptop Per Child, said it plans to launch a basic tablet computer for $99. Sibal turned to students and professors at India's elite technical universities to develop the $35 tablet after receiving a "lukewarm" response from private sector players. He hopes to get the cost down to $10 eventually. Mamta Varma, a ministry spokeswoman, said falling hardware costs and intelligent design make the price tag plausible. The tablet doesn't have a hard disk, but instead uses a memory card, much like a mobile phone. The tablet design cuts hardware costs, and the use of open-source software also adds to savings, she said. Varma said several global manufacturers, including at least one from Taiwan, have shown interest in making the low-cost device, but no manufacturing or distribution deals have been finalized. She declined to name any of the companies. India plans to subsidize the cost of the tablet for its students, bringing the purchase price down to around $20. "Depending on the quality of material they are using, certainly it's plausible," said Sarah Rotman Epps, an analyst at Forrester Research. "The question is, is it good enough for students?" Profitability is also a question for the $35 machine. Epps said government subsidies or dual marketing - where higher-priced sales in the developed world are used to subside low-cost sales in markets like India - could convince a manufacturer to come on board.

This and similar efforts - like the Kakai Kno and the Entourage Edge tablets - show that there is global demand for an affordable device to trim high textbook costs, she said. If it works, Epps predicts the device could send a shiver of cost-consciousness through the industry. "It puts pressure on all device manufacturers to keep costs down and innovate," she said. The project is part of an ambitious education technology initiative by the Indian government, which also aims to bring broadband connectivity to India's 25,000 colleges and 504 universities and make study materials available online. So far nearly 8,500 colleges have been connected and nearly 500 web and video-based courses have been uploaded on YouTube and other portals, the Ministry Read more at: http://www.ndtv.com/article/technology/india-unveils-prototype-of-35-tablet-computer-39424?cp

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Science is facts; just as houses are made of stone, so is science made of facts; but a pile of stones is not a house, and a collection of facts is not necessarily science. Jules Henri Poincaré French athematician Anybody who has been seriously engaged is scientific work of any kind realizes that over the entrance to the gates of the temple of science are written the words: 'Ye must have faith.' Max Planck ----------------------------------------------------

http://www.ndtv.com/article/technology/india-unveils-prototype-of-35-tablet-computer-39424?cp



http://www.brainyquote.com/quotes/quotes/m/maxplanck126264.html


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Dr. Bikul Das (MBBS, PhD) is presently working as a postdoctoral fellow in the division of medicine oncology in Stanford University, California. He joined Stanford as a recipient of prestigious “Grand Challenge Grant Award”, Bill and Melinda Gates Foundation for 2009-2010. He got his PhD in Medical Science (Molecular Oncology) from University of Toronto, Canada and continued to work as a postdoctoral fellow in the same institute during the period 2007-2009. Prior to his PhD, he completed his MBBS degree from Guwahati Medical College and Hospital. Before moving to Canada, he worked as a Senior House Officer in the division of Internal Medicine, Mongar Referral Hospital, Bhutan as well as a house officer in internal medicine at Guwahati Medical College and Hospital. He established Micro Clinic, in Sualkuchi, Assam, in 1993. He also helped in the establishment of North East Medical Care and Research Center, Guwahati, Assam.

Other than Grand Challenge award he is the recipient of many other prestigious fellowships that includes Harold E. Johns Award by Canadian Cancer Society (2009), Schweisguth prize; International Society of Pediatric Oncology Research Association (2008), Schweisguth Prize, International Society of Pediatric Oncology (SIOP), Netherland (2008), Hind rattan award (2007) etc. His main research interest is in developing an appropriate experimental system to study the stable Vs unstable state of stemness state. His work has been published in various Book series as well as internationally reputed journals. Dr Bikul Das is also associated with Bhagawati Samaj Sewa that works towards the improvement of social and spiritual health of people living in rural Assam. His present email: [email protected] ------------------------------------------------------

Science information through the lens

This is not an art; these are the micro-organisms that grow at the edge of hot basins in Yellowstone National Park, USA.

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Mathematics as a Career

Dr. Shanta Laishram

Is there anything more to do than 1 + 1 = 2?

That’s the perception many people have for mathematics! Quite a lot of people think that mathematics is dry and very difficult which is not quite true. In fact many people are just frightened by the name of mathematics. GH Hardy, one of the most well-known mathematicians of the last century, wrote in the book A Mathematician’s Apology (London 1941, pp. 14): The fact is that there are few more “popular” subjects than mathematics. Most people have some appreciation of mathematics, just as most people can enjoy a pleasant tune; and there are probably more people really interested in mathematics than in music. Appearances may suggest the contrary, but there are easy explanations. Music can be used to stimulate mass emotion, while mathematics cannot; and musical incapacity is recognized (no doubt rightly) as mildly discreditable, whereas most people are so frightened of the name of mathematics that they are ready, quite unaffectedly, to exaggerate their own mathematical stupidity. If you think Mathematics is difficult and useless, think again. Today you may be counting numbers as if it is very natural. You are using internet securely and sing ATM Cards and unknowingly, primes are used. There are lots of other examples where mathematics is used. But I am going to tell you about a career in mathematics and how is it being a mathematician.

Who is a Mathematician?

A person who does mathematics is a mathematician. Unlike many other areas of science or engineering or other fields, mathematics is something which you can do all over your life. Paul Erd˝os, one of the most prolific mathematicians of the last century, rightly said: “Mathematicians never die, they just stop doing mathematics!” A working mathematician is person who contributes in the advancement of mathematical knowledge by way of teaching, research and sharing knowledge. To become a mathematician, one needs to be trained in mathematical thinking by way of exposing to different areas and needs to learn a lot of related materials. In the next section, i will mention the different ways on how to become a working mathematician.

Why one does wants to be a Mathematician? This is question which many people may be planning to ask! A mathematician, if interested in mathematics, can work all the time without getting bored. Also the pleasure of proving some theorem of your own which no one has ever found is something really fulfilling. When I proved my result (theorem) for the first time, I find it really pleasurable. The happiness I felt is something I can not really express. As most of you might have noticed, solving a problem which others feel is difficult is a pleasure in itself and here finding and inventing a new result on your own is something very exciting! Also solving the problems which have implications in other areas of science and day to day life is a source of immense joy.


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One has to also understand that staying in academics and research is not very highly paid as those working for Financial and other company jobs. However it pays you sufficiently to have a very good and decent life for you and your family. After all, money is not everything. The pleasure of working with freedom and contributing and inventing something new and sharing knowledge is what makes people interested to continue in academics and research.

How to become a Mathematician?

A student who wants to become a mathematician has to study mathematics upto certain level and go for PhD. Usually, students need to do Master in Mathematics after their Bachelors degree and then go for PhD programs. However nowadays, there are courses which train students for mathematics right after class XII. Students can go for Integrated Masters program at Indian Institute of Science Education and Research (IISER)s at Bhopal, Mohali, Kolkata, Pune and Trivandrum, National Institute of Science Education and Research(NISER) at Bhubaneshwar, Centre for Basic Sciences(CBS) at Mumbai and some of the Indian Institute of Technology(IIT)s like IIT Kanpur. It is worth knowing that students admitted at IISER, NISER, CBS get a fellowship of Rs 5000 per month currently. Currently some of the best places for doing undergraduate (BSc) courses in Mathematics are at B. Math programs at Indian Statistical Institutes (Kolkata, Blore and Delhi) and at Chennai Mathematical Institute (CMI) in Chennai. Some of the BSc programs at Central Universities are also considered very good.

However one should not worry if you cannot get though at the above institutes. Students can go for good Masters programs at IITs and Integrated PhD program at Indian Institute of Science (IISc) Blore and at other universities. Also BSc passed students can go for PhD program directly at Tata Institute of Fundamental Research (TIFR) Mumbai, Institute of Mathematical Sciences (IMSc) Chennai and Harish-Chandra Research Institue(HRI) Allahabad where they will be given Masters Degree in addition to PhD Degree. Those students who have a Master Degree can apply for PhD programs at leading institutes in India and Abroad. TIFR, IMSc, HRI, IISc, IITs and IISERs and above institutes are very good places for PhD programs in India. Though students need to get CSIR-UGC Junior Research Fellowship (JRF) for getting into some of the institutes and universities, TIFR, IMSc, HRI, IISc, IISER, NISER has its own selection procedure. Also there are lots of opportunities for pursuing PhD at Universities abroad particularly in US, Canada and European Universities. Though students usually need to write Graduate Record Examination (GRE) for admission into US universities, GRE is not usually required for Canada and European universities. University of Princeton, University of California, Berkely, Harvard Univ, MIT, Stanford, Yale, Chicago, Cambridge, Oxford are some of the top places for mathematics in the world. Career opportunities of a Mathematician Mathematicians are usually involved in research and teaching positions in Universities and Institutes. However recently, there have been job opportunities for mathematicians (even with those with


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Masters even) in Industry, particularly banking and finance. Also Mathematicians are employed at various governmental organisations like ISRO (Indian Space Research Organisation), DRDO (Defence Research and Development Organisation) and DAE (Department of Atomic Energy). How does one prepare to become a Mathematician? A student can start preparations to become a mathematician at any given time in their life though it is always preferable to start early. As some of you might have heard, Olympiad programs are a good way to start in mathematics though its not the best way. Even if you do not do well in mathematics at school level, there is nothing to worry about. You can pick up at college and masters level. Main thing needed for being a mathematician is having patience and willing to learn. There is no place for lazy people in mathematics. What mathematics teaches is being logical in life and not to believe things blindly. It trains you in reasoning. So, even if you do not become a well known mathematician, you become a nice and reasonable human being. How I came into Mathematics

Since childhood, I have been interested in mathematics, particularly solving problems. I used to solve the exercises just after teacher starts teaching the chapters and sometimes before that. When I got 99 out of 100 in my Class 10th exam (by CBSE, New Delhi), I became more interested in mathematics. I also liked solving Olympiad problems during my Class 11 - 12. Main motivation came when I was attending Mathematics Training and Talent Search program sponsored by NBHM. I

attended it first time at IIT Chennai where I got to interact with mathematicians from well known institutes and students from all over the country and it was very motivating. After that I got to be in touch with some faculties at HRI and IMSc and attended some summer programs. Finally I joined TIFR after my BSc for PhD program and since then I have been working as a mathematician. One interesting aspect of being a mathematician is to get opportunities to travel and interact with mathematicians working in related areas from all over the world. I have been lucky enough to travel at many important places in the world. Also, one has the enough freedom to work anytime. Of course, sometimes you may be thinking on a problem and you may continue to think on that even when you are walking or eating, without bothering about other things. But the real joy is when you get an interesting idea to solve a problem. Perhaps this prompted Hardy to say “If I could find a proof that you were going to die in five minutes, I would of course be sorry to lose you, but the sorrow would be quite overweighed by the pleasure in the proof” while talking to Bertrand Russell. Russell entirely sympathized with him and was not at all offended!!! But one thing which we have to remember is that there is no substitute for hard work and patience pays. Important organizations and programs for mathematics

• National Board for Higher Mathematics (NBHM) gives scholarships and funds math programs. http://www.nbhm.dae.gov.in

• Mathematics Training and Talent

Search Program http://www.mtts.org.in

http://www.nbhm.dae.gov.in/


15

• Kishore Vaigyanik Protsahan Yojana(KVPY) http://www.iisc.ernet.in/kvpy

• Summer Research Fellowships

Programme of JNCASR, Bangalore http://www.jncasr.ac.in/extn_prog/srfp

• Visiting Students’ Research

Programme (VSRP) at TIFR http://www.tifr.res.in/vsrp

• Summer Programme in Mathematics

in HRI http://www.hri.res.in/vsp_ maths.html

• Indian Academy of Sciences

Summer Fellowships http://www.ias.ac.in

• IISER Admissions http://iiser-

admissions.in

• National Entrance Screening Test (NEST) http://www.nestexam.in

Well known Institutes for mathematics (not the exclusive list)

• Tata Institute of Fundamental Research (TIFR) Mumbai.

http://www.tifr.res.in • Institute of Mathematical Sciences

(IMSc) Chennai. http://www.imsc.res.in

• Indian Statistical Institute (ISI)s at

Kolkata, Delhi and Bangalore. http://www.isical.ac.in

• Harish-Chandra Research Institute

(HRI) Allahabad. http://www.hri.res.in

• Chennai Mathematical Institute (CMI) Chennai http://www.cmi.ac.in

• Indian Institute of Science (IISC)

Bangalore http://www.iisc.ernet.in

• Indian Institute of Science Education and Research (IISER)

http://www.iisercity.ac.in

• National Institute of Science Education and Research Bhubaneshwar

http://www.niser.ac.in

• Centre for Basic Sciences Mumbai http://www.cbs.ac.in

• Indian Institute of Technology(IIT)s at Chennai, Delhi, Guwahati, Kanpur, Kharagpur, Mumbai, Roorkee, Patna, Indore, Ropar,

Gandhinagar, Hyderabad, Bhubaneshwar

• Jawaharlal Nehru University Delhi http://www.jnu.ernet.in

• Central University Hyderabad

(HCU) http://www.uohyd.ernet.in

• Panjab University Chandigarh http://www.pu.ac.in

• University of Mumbai, Mumbai

http://www.mu.ac.in

The author is presently working as an Assistant Prof. in ISI Delhi. Email: [email protected]

----------------------------------------------

http://www.tifr.res.in/vsrp

http://www.hri.res.in/vsp_%20maths.html

http://www.hri.res.in/vsp_%20maths.html

http://www.ias.ac.in/

http://www.imsc.res.in/

http://www.isical.ac.in/

http://www.hri.res.in/

http://www.cmi.ac.in/

http://www.iisc.ernet.in/

http://www.iisercity.ac.in/

http://www.cbs.ac.in/

http://www.jnu.ernet.in/

http://www.uohyd.ernet.in/

http://www.pu.ac.in/


16

Historical Developments and Present Trends of Research in Soft

Magnetic Materials

Dr. M P C Kalita

Abstract

Ferromagnetic materials with coercivity typically below 100 Oe are known as soft magnetic materials (SMM). SMM materials find wide applications in transformer cores, electrical appliances, magneto fluids etc. Coarse grained Fe-Si soft magnetic alloys were developed as early as 1900. Since then a significant progress in the development of SMM occurred with coercivity as low as below 10-3 Oe obtained in nanocrystalline and amorphous SMM which were developed in the 1970 and 1980s. In this article, the historical development of SMM and its present trend of research have been discussed. Introduction

Ferromagnetic materials are classified as ‘soft’ or ‘hard’ based on their coercive field or simply coercivity. Usually, materials with coercivity less than 100 Oe are considered to be soft, while those with coercivity above 1000 Oe are termed hard magnetic materials. The coercivity, is known to depend on the composition and microstructure of the material. In the early days, magnetic materials were mainly prepared by casting process. These early magnetic materials are known to get harder (i.e. exhibit an increase in coercivity) with a decrease in their crystallite size [1]. Therefore, early research activities on soft magnetic materials were mainly confined to the development of appropriate alloys with large crystallite sizes, so that materials with better soft magnetic properties could be obtained [2]. However, this approach

changed after the discovery of amorphous soft magnetic materials prepared by rapid solidification technique [3] and more recently after the advent of ultra fine magnetic materials with crystallite size of the order of 10 nm prepared by controlled crystallization of melt-spun amorphous precursor [4]. Applications of Soft Magnetic Materials The applications of SMM fall into two broad categories, viz. AC and DC applications. For AC applications, the important consideration is how much energy is lost in the system as the material is cycled around its hysteresis loop. The energy loss originates from two main sources viz. hysteresis loss (which is the area enclosed by the hysteresis loop) and eddy current loss (which is related to the generation of electric currents in the magnetic material and the associated resistive losses). Hysteresis losses can be reduced by the reduction of the coercivity, with a consequent reduction in the area enclosed by the hysteresis loop. Eddy current losses can be reduced by increasing the electrical resistivity of the material and by laminating the material. In DC applications, the material is magnetized in order to perform an operation and then demagnetized at the conclusion of the operation. The development of SMM has been mainly driven by the search for superior soft magnetic alloys and to meet the requirements of applications. Recent research has been focused on achieving materials with low coercivity, high permeability and high saturation magnetization in a cost effective way. The continuing development of better materials has considerably improved the efficiency of key building blocks of present electrical


17

appliances like motors, generators, transformers, inductors, etc. Conventional Soft Magnetic Alloys Among the soft magnetic alloys (SMA) which find wide applications, Fe-Si is one of the earliest to be discovered. Barrett et al. [5] reported the improvement in the soft magnetic properties of Fe with the addition of Si in 1900. Significant progress occurred after the discovery of grain-oriented Fe-Si alloys and Ni-Fe alloys such as permalloy in the 1940s [6]. The range of SMM was further extended by the development of ferrites in the 1950s [6]. The major families of the conventional SMA with important applications are briefly discussed below. Fe-Si alloys In electrical power generation and transmission, the highest demand is for transformer cores. Fe-Si alloys are used for transformer cores in exclusion of all other SMA and are commonly known as ‘electrical steels’ or ‘silicon steels’. In the power industry, electrical voltage is almost always AC and at low frequency (50 - 60 Hz). At these frequencies, eddy currents are generated in the transformer core. Silicon is a less costly and easily available material and therefore gets importance to meet the huge demands of transformer core materials in large quantities. Addition of Si in Fe reduces the magnetocrystalline anisotropy and magnetostriction (i.e. length change on magnetization) of Fe and thereby reduces the coercivity. Further, the resistivity of Fe increases with the addition of Si and thereby reduces the eddy current losses. The addition of too much of Si makes the material extremely brittle and difficult to

produce, resulting in a practical limitation of the additive to 4 wt %. Often Al is added in Fe-Si alloys to increase the ductility of the alloy. Alloys with atomic composition Fe75Si15Al10 (known as Sendust) are used as electrical steels for some special applications. Selected magnetic properties of some Fe-Si alloys are listed in Table 1.

Ni-Fe alloys These alloys, known as permalloy, are extremely versatile and are used over a wide range of compositions (from 30 to 80 wt% Ni). Over this composition range, the properties vary considerably and the optimum composition must be selected for a particular application. There are special grades of Ni-Fe alloys that have zero magnetostriction and zero magnetic anisotropy, such as mumetal which is produced by a careful heat treatment and minor additions of Cu and Cr. These alloys have extremely high relative permeability (up to 300000), and coercivity as low as 0.005 Oe. However, low saturation magnetization and the high cost of Ni as compared to Si limits these alloys only for some special applications. Selected magnetic properties of some Ni-Fe alloys are listed in Table 2. Fe-Co alloys These alloys have higher saturation magnetization than pure Fe. They have both AC and DC applications, but high ost of Co has limited their applications only for some special purposes. Selected magnetic properties of some Fe-Co alloys are listed in Table 3.


18

Table 1 : Selected magnetic properties of some Fe-Si alloys [Ref. 7].

Table 2: Selected magnetic properties of some Ni-Fe alloys [Ref. 7]

Fe-Si Alloy Composition Maximum

Permeability, µµµµmax

Coercivity,

HC (Oe)

Saturation

Polarization, JS (T)

Fe-Si

(Non-oriented)

Fe96Si4 4000 - 15000 0.4 - 1.5 2.1

Fe-Si

(Non-oriented)

Fe97.5Si2.5 4000 - 12000 0.15 - 1.5 2.0

Fe-Si

(Non-oriented)

Fe96Si4 5000 - 20000 0.5 - 1 2.0

Fe-Si

(Grain-oriented)

Fe97Si3 40000 0.1 2.0

Alloy Composition Maximum

Permeability,

µµµµmax

Coercivity,

HC (Oe)

Saturation

Polarization, JS

(T)

78 Permalloy Ni78Fe22 8000 0.05 1.08

Hipernik Ni50Fe50 4000 0.05 1.60

Supermalloy Ni79Fe16Mo5 100000 0.005 0.79

Mumetal Ni77Fe16Cu5Cr2 20000 0.05 0.65


19

Table 3: Selected magnetic properties of some Fe-Co alloys [Ref. 7].

Alloy Composition Maximum

permeability, µµµµmax

Coercivity,

HC (Oe)

Saturation

Polarization, JS (T)

Permendur Fe50Co50 5000 0.05 2.45

Supermendur Fe49Co49V2 60000 1 2.40

Soft Ferrites At high frequencies, metallic SMM simply cannot be used due to the eddy current losses. Therefore, soft ferrites, which are ceramic insulators, become the most desirable material. These materials are ferrimagnetic with the general chemical formula MO.Fe2O3, where M is a transition metal. Mn-Zn ferrite, commercially known as ferroxcube, can be used at frequencies up to 10 MHz, for example in telephone signal transmitters / receivers and in switch mode power supplies [7]. Amorphous and Nanocrystalline Soft Magnetic Alloys Remarkable progress in SMM took place in 1970s and 1980s with the advent of rapid solidification technique (RST) which provided a route to produce magnetic materials with new compositions and microstructure. Amorphous materials (also called metallic glasses) produced by RST are attractive candidates to replace the conventional spectrum of SMM in both DC and AC applications. Selected magnetic properties of some amorphous materials prepared by RST are listed in Table 4. Since the discovery of amorphous SMA in 1970s, crystallization of the amorphous

precursors was known to yield coarse grain microstructure with crystallite size of about 0.1-1µm with deterioration of the soft magnetic properties. However, a historical milestone in magnetic materials was achieved by Yoshizawa et al. [4] in 1988, who found that crystallization of Fe(Si,B) glasses with the combined addition of small amounts of Cu and Nb yields an ultrafine grain structure of bcc Fe(Si) with crystalline size ~10-15 nm embedded in a minority amorphous matrix. These nanocrystalline alloys were found to exhibit coercivity ~10-3 Oe previously obtained only in case of permalloys and Co-based amorphous alloys. The significance of the these nanocrystalline alloys is that ultra low coercvity could be obtained in Fe-Si based alloys with high saturation polarization of 1.2 T or even more with the potential of a huge impact in all soft magnetic applications. Typical structural and magnetic parameters of some nanocrystalline alloys are listed in Table 5.


20

Table 4: Selected magnetic properties of some amorphous alloys prepared by RST [Ref. 8].

Alloy composition Coercivity, HC (Oe) Saturation polarization, JS (T)

Co68Fe4(MoSiB)28 0.004 0.55

Co72(FeMn)5(MoSiB)23 0.006 0.8

Fe76(SiB)24 0.04 1.45

Table 5: Typical structural and magnetic parameters of some nanocrystalline alloys

Alloy composition Crystallite size, D (nm)

Coercivity, HC (Oe)

Saturation Polarization, JS (T)

Reference

Fe73.5Cu1Nb3Si13.5B9 13 0.006 1.24 [4]

Fe73.5Cu1Nb3Si15.5B7 14 0.005 1.23 [9]

Fe84Nb7B9 9 0.1 1.49 [9]

Fe86Cu1Zr7B6 10 0.04 1.52 [9]

Fe91Zr7B2 17 0.07 1.63 [9]

Origin of Soft Magnetism in Nanocrystalline Materials The coercivity of a material is strongly dependent on its microstructure. The crystallite size and defects like grain boundaries, non-magnetic inclusions and internal stresses influence the coercivty. According to Mager [10], the coercivity determined by grain boundaries is a linear function of the reciprocal of the diameter of the crystallite, D, according to the relation

DJ

HS

WC

13γ

≈ (1)

where, γW is the domain wall energy and JS is the saturation polarization. The wall energy can be expressed as [11]

aKkTCW /=γ (2) where k is the Boltzmann constant, TC is the Curie temperature of the material, K is the magnetocrystalline anisotropy and a is the lattice parameter. From equations (1) and (2), one can write

DJ

aKkTH

S

CC

1/3≈ (3)


21

However, the D-1 dependence on coercivity is valid only when the crystallite size is higher than the ferromagnetic exchange length (FEL) where the magnetization is governed mainly by the magnetocrystalline anisotropy of the crystallites [11]. FEL is a basic parameter in domain theory which characterizes a minimum range over which the magnetization can vary appreciably and can be expressed as [11]

KA

Lex = (4)

where A is the exchange stiffness constant and K is the magnetocrystalline anisotropy constant. It determines the barrier between single domain and multi domain structures. For crystallite size less than the ferromagnetic exchange length, magnetization process is governed by the interplay of magnetocrystalline anisotropy of the crystallites and the ferromagnetic exchange energy. The theoretical model by Herzer known as random anisotropy model (RAM) [13] which explains the origin of ultra low coercivity in nanocrytalline ribbons is briefly discussed below. The RAM was originally proposed by Alben et al. [14] for amorphous ferromagnets. Herzer applied it to explain the ultra low coercivity in nanocrystalline ribbons. The basic idea of RAM is depicted in Figure 1.2. It shows an assembly of randomly oriented ferromagnetically coupled crystallites of size D with magnetocrystalline anisotropy constant K. The effective magnetocrystalline anisotropy affecting the magnetization process results from averaging over the ( )3/ DLN ex=

crystallites within the volume 3exLV = of the

exchange length. For a finite number, there

will always be some easiest direction determined by the statistical fluctuations. As a consequence, the resulting anisotropy K is determined by the mean fluctuating amplitude of anisotropy energy of N crystallites, which is given by

2/3

=≈

exLD

KNK

K (5)

Fig. 1: Schematic representation of RAM. The solid arrows indicate the randomly fluctuating magnetocrystalline anisotropy.

In turn, the exchange constant is now

related self consistently to the average anisotropy by substituting K for K in equation (5), i.e.

KA

Lex = (6)

As magnetocrystalline anisotropy is suppressed by exchange interaction, the scale on which exchange interaction dominate expands at the same time, and thus local anisotropies are averaged out more


22

effectively. The combination of equations (5) and (6) results in

63

4

DAK

K ≈ (7)

This relation is valid as long as the crystallite size is less than the ferromagnetic exchange length Lex. The coercivity (HC) can be related to K using the relation between HC and magnetocrystalline anisotropy for coherent rotation of spins [15]

3

6

AJKD

pJK

pHS

CS

CC ≈= (8)

where pC is a dimentionless parameter, JS is the saturation polarization and A is stiffness constant. Accordingly, coercivity varies as D6 when D is less than the ferromagnetic exchange length. This is known as D6 law for nanocrystalline materials and it explains the origin of soft magnetism in nanocrystalline ribbons. Mechanically Alloyed Soft Magnetic Materials

In recent years, mechanical alloying (MA) has drawn a lot of research interest because of its versatility to prepare nanocrystalline soft magnetic alloys in a wide range of compositions in powder form with relatively inexpensive equipments. Melt spun nanocrystalline ribbons are thin and usually brittle, which restricts their applications mainly to toroidal cores. These limitations can be overcome by the preparation of soft magnetic alloys by MA. Table 6 summarizes the coercivity of mechanically alloyed nanocrystaline soft magnetic powders reported in the literature.

The crystallite size of the nanocrystalline powders mentioned in Table 6 is mostly in the range 10-20 nm. However, the value of coercivity in the mechanically alloyed nanocrystalline powders has been reported to be higher as compared to nanocrystalline melt-spun ribbons (HC ~10-3 Oe). The higher values of coercivity have been mainly attributed to the high strain and dislocations induced during the milling process. In most of these reports, saturation magnetization has been reported to be slightly less than that of pure Fe and independent of microstructure.

Table 6: Coercivity of mechanically alloyed nanocrystalline powders

Material Coercivity (Oe) Ref.

Fe100-xSix (x = 6.5 – 25) 120 - 140 [16]

Fe100-xSix (x = 0 – 40) 2.4 - 7.4 [17]

Fe100-xSix (x = 6.5 –20); Fe83.5Si13.5Nb3 53 - 65 [18]


23

Fe75Si25 50-120 [19,20]

Fe100-xMx (M = Al, Si, Cu; x = 0 – 50) 3.8 - 50 [21]

Fe75Si25-xMx (M=Al,B,Cr;x=5,10) 20-150 [22,23]

Fe75Nb10Si5B10 50 - 95 [24]

Conclusion The development of SMM has seen a rapid change after the advent of amorphous and nanocrystalline alloys. They offer a new possibility of tailoring superior SMM with high saturation magnetization. Although nanocrystalline magnetic materials can be obtained in a cost effective way by mechanical alloying process, obtaining low coercivity comparable to those prepared by crystallization of rapidly solidified alloys still remains a challenge for the researchers. Reference [1] G. Herzer, Physica Scripta T 49 (1993)

307. [2] F. Ffeiffer and C. Radeloff, J. Magn.

Magn. Mater. 19 (1980) 190. [3] R. Boll and H. R. Hildnger, IEEE Trans.

Magn. MAG-19 (1983) 1946. [4] Y. Yoshizawa, S. Oguma and K.

Yamauchi, J. Appl. Phys. 64 (1988) 6044.

[5] W. F. Barrett, W. Brown and R. A. Hadfield, Sci. Trans. R. Dublin Soc. 7 (1900) 7.

[6] G. E. Fish, Proceedings of IEEE 78 (1990) 978. [7] D. Jiles, Introduction to Magnetism and Magnetic Materials, Chapman & Hall, Newyork, (1991). [8] G. Herzer, Proceedings of the NATO Advanced Study Insititute on Magnetic Hysteresis in Novel Materials 338 (1996) 711. [9] K. Suzuki, A. Makino, N. Kataoka, A.

Inoue and T. Masumoto, J. Appl. Phys. 70 (1991) 6232.

[10] A. Mager, Ann. Phys. 6 F (1952) 15. [11] S. Blundel, Magnetism in condensed matter, Oxford University Press, (2001). [12] J. S. Benjamin and M. S. Bamford, Metall. Trans. A8 (1977) 1301. [13] G. Herzer, IEEE Trans. Magn. 26 (1990) 1397. [14] R. Alben, J. J. Baker and M. C. Chi , J. Appl. Phys. 49 (1978) 1653.


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[15] R. M. Bozorth, Ferromagnetism, Princeton, N. J.: D. Van Nostrand, (1951). [16] T. J. Zhou, Z. Yu and Y. W. Du, J.

Magn. Magn. Mater. 202 (1999) 354. [17] J. Ding, Y. Li, L. F. Chen, C. R. Deng,

Y. Shi, Y. S. Chow and T. B. Gang, J. Alloys Compd. 314 (2001) 262.

[18] S. Miragheai, P. Abachi, H. R. M.

Hosseini and A. Bahrami, J. Mater. Process. Tech. 203 (2008) 554.

[19] M. P. C. Kalita, A. Perumal and A.

Srinivasan, J. Magn. Magn. Mater. 320 (2008) 2780.

[20] M. P. C. Kalita, A. Perumal and A. Srinivasan, J. Phys D: Appl. Phys. 42 (2009) 105001.

[21] C. Kuhrt and L. Schultz, IEEE Trans.

Magn. 29 (1993) 2667. [22] M. P. C. Kalita, A. Perumal and A.

Srinivasan, J. Phys D: Appl. Phys. 41 (2008) 165002.

[23] M. P. C. Kalita, A. Perumal, A.

Srinivasan, B. Pandey and H.C.Verma, J. Nano. Sci. Nano Tech. 8 (2008) 4314.

[24] J. J. Sunol, L. Escoda, J. Fort, J. Perez

and T. Pujol, Mater. Lett. 62 (2008) 1673.

The author is working as an Assistant Prof. at Department of Physics, Gauhati University Email: [email protected]

------------------------------------------------------- Electrocatalysis, Fuel cell, Oxygen

reduction reaction, etc

Dr. Pankaj Bharali Spurred on by society's increasingly urgent demand for an inexpensive, environment-friendly alternative to the internal combustion engine, research into electrocatalytic fuel cells has yielded many exciting advances in the past few years. This rapid rate of progress, however, has created a daunting challenge for anyone attempting to track the important new trends in electrocatalysis. Electrocatalysis was designed to save scientists hours of arduous legwork by providing an authoritative review of the most important recent advances in all technologically relevant aspects of electrocatalysis. Electrocatalysis is an indispensable working resource for electrochemists, chemical engineers, surface

scientists, and materials scientists. Recent research in the field of electrocatalysis involves though not limited to the following processes are-

* Electrocatalysis of hydrogen and oxygen electrode reactions * Electrooxidation of small organic molecules * Design and synthesis of new electrocatalytic materials * The distribution and storage of hydrogen in metal hydrides * Hydrogenation of organic compounds as a means of hydrogen storage * Electron, ion, and atom transfer reactions


25

* Influence of the double-layer structure on the rate of charge transfer

* A unified theory of electron and ion transfer reactions at metal electrodes

Fuel cells are electrochemical devices that directly convert chemical energy into electrical energy with high efficiency and low emission of pollutants. They consist of an electrolyte medium sandwiched between two electrodes (Figure 1). One electrode (called the anode) facilitates electrochemical oxidation of fuel, while the other (called the cathode) promotes electrochemical reduction of oxidant. Ions generated during oxidation or reductions are transported from one electrode to the other through the ionically conductive but electronically insulating electrolyte. The electrolyte also serves as a barrier between the fuel and oxidant. Electrons generated at the anode during oxidation pass through the external circuit (hence generating electricity) on their way to the cathode, where they complete the reduction reaction. The successful conversion of chemical energy into electrical energy in a primitive fuel cell was first demonstrated over 160 years ago. However, in spite of the attractive system efficiencies and environmental benefits associated with fuel-cell technology, it has proved difficult to develop the early scientific experiments into commercially viable industrial products. These problems have often been associated with the lack of appropriate materials or manufacturing routes that would enable the cost of electricity per kWh to compete with the existing technology.

The types of fuel cells under active

development are summarized in Figure 1. The oxidation reaction takes place at the anode (+) and involves the liberation of

electrons (for example, O2– + H2 = H2O + 2e– or H2 = 2H+ + 2e–).

Fig. 1 Summary of fuel-cell types

These electrons travel round the external circuit producing electrical energy by means of the external load, and arrive at the cathode (–) to participate in the reduction reaction (for example, ½ O2 + 2e– = O2– or ½ O2 + 2H+ + 2e– = H2O). It should be noted that as well as producing electrical energy and the reaction products (for example, H2O and CO2), the fuel-cell reactions also produce heat. The reaction products are formed at the anode for solid-oxide fuel cells (SOFC), molten-carbonate fuel cells (MCFC) and alkaline fuel cell (AFC) types, and at the cathode for phosphoric-acid fuel cell (PAFC) and polymeric-electrolyte-membrane fuel cell (PEMFC) types. This difference has implications for the design of the entire fuel-cell system, including pumps and heat exchangers. To maintain the composition of the electrolyte component in the MCFC system, CO2 has to be recirculated from the anode exhaust to the cathode input. Additionally, the composition of the polymeric-membrane electrolyte has to be carefully controlled during operation by an appropriate ‘water management’ technology.


26

The AFC, PEMFC and PAFC stacks essentially require relatively pure hydrogen to be supplied to the anode. Accordingly, the use of hydrocarbon or alcohol fuels requires an external fuel processor to be incorporated

into the system. This item not only increases the complexity and cost of the system, but also decreases the overall efficiency as indicated in Figure 2.

Fig. 2 Fuel-cell types and fuel processing

Although selected fuels can be introduced directly into the anode compartment of the high-temperature fuel cells (SOFC and MCFC), better thermal management of the stack can usually be achieved by having separate reformer compartments that are thermally integrated within the stack to produce a mixture of fuel and syngas (H2 and CO). For the lower-temperature fuel cells (PAFC and PEMFC), external reformers are required. Some of the fuel has to be consumed in these external reformers to maintain the operating temperature. Moreover, dilution of the H2 fuel reduces performance of the cells, resulting in significant efficiency losses compared with operation on pure H2. It should be noted that the AFC stack cannot be operated on

reformate fuels because of the presence of CO2 in these gases. In contrast, MCFCs and SOFCs operating at higher temperatures have the advantage that both CO and H2 can be electrochemically oxidized at the anode. Moreover, the fuel-processing reaction can be accomplished within the stack, which enables innovative thermal integration/management design features to provide excellent system efficiencies (~50%). Fuel cell reactions invariably involve oxygen reduction at the cathode. Normally the fuel cell developers concentrate on the anode electrode since this is involved in the combustion of the fuel and hence directly involved in the performance of the fuel cell.


27

However, the counter cathode reaction is also equally important and developing suitable electrode which can promote oxygen reduction reaction (ORR) in an appropriate manner in terms of the suitable electrode, reaction kinetics and also stability under the operating conditions and atmosphere are important factors that have been considered so far. The ORR is a multi-electron reaction that proceeds via several elementary steps. In aqueous solutions on electrodes, it appears to occur in two pathways: (i) A “direct” four-electron reduction, wherein four electrons are transferred in concert

and (ii) A “series” pathway that involves H2O2 as the intermediate:

A series four-electron reduction involves the transfer of two electrons to form peroxide, which, without leaving the electrode’s surface, is further reduced to H2O with the exchange of an additional two electrons and two protons. There are three possible first steps in the ORR: (i) splitting of the O-O bond upon adsorption on two metal sites (S) in a bridge configuration, O2 + 2S → O* + O*; (ii) formation of the superoxide anion, O2 + 2S + e− → O2−; and (iii) simultaneous electron and proton transfer, O2 + 2S + (H+ + e−) → HO2. Identifying the first step would clarify the pathway of the ORR that takes place on catalytically active metal surfaces. The role of the superoxide anion and the details of the

reaction mechanism on surfaces supporting a four-electron reduction pathway still defy an unquestionable description. Such information is essential for further advances in electrocatalysis since it could resolve the question of the first reaction step on metal-a prerequisite for formulating the reaction mechanism on a molecular level and defining the right approach for designing new electrocatalysts. It has been always advocated that Pt supported on carbon or alloys of Pt are the better known cathodes for Fuel cell applications. There have been various attempts in the literature using various other types of alloys, (mostly non noble metal based ones) some complexes involving phthalocyanines (may be mimicking the biological systems) and some cluster compounds. The above materials have been chosen with some prior input like they function in natural systems or they have some parameters like (reduction) potential appropriate for oxygen reduction. It is however necessary to consider a few other factors in conjunction with these basic postulates namely the reducing capacity of the electrode or to effect the transfer of electrons to the substrate ( in this case oxygen) based on its acceptor levels. The further few points to be considered are: 1. In biological systems the reduction reaction takes place in an atmosphere and how does this alter the reduction state of oxygen has to be carefully analyzed and appropriate remedies to be sought in the practical chemical systems. 2. It may be necessary to incorporate alternate cluster systems not only matching the electronic energy levels appropriate for charge transfer between the electrode and the reducing species namely molecular


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oxygen, but the formulation has to plug in information on the stability, kinetics of electron transfer and also the possibility of the system formulated to activate molecular oxygen on its surface. 3. It is possible to bring in new concepts like MN4 type clusters which can effect the reduction of oxygen in a facile manner from the point of view of energetics. The relevance of these systems to satisfy other conditions has to be examined. It is hoped that newer insights will evolve on these points and any other points that may arise for this important reaction in the near future.

References 1. Wikipedia, http://en.wikipedia.org/ 2. B. C. H. Steele, A. Heinzel, Nature

2001, 414, 345. 3. M. Shao, P. Liu, R. R. Adzic, J. Am.

Chem. Soc. 2006, 128, 7408. 4. J. Wu, J. Zhang, Z. Peng, S. Yang, F. T.

Wagner, H. Yang, J. Am. Chem. Soc. 2010, 132, 4984.

5. B. Viswanathan, C. V. Rao, U. V. Varadaraju, Photo/Electrochem. & Photobio. Environ., Energy and Fuel, 2006, 43.

.

The author is a postdoctoral fellow at the Research Institute for Ubiquitous Energy Devices, AIST-Kansai, Japan. Email: [email protected]

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Stem Cells and Their Potential Applications in Therapeutics

Dr. Khirud Gogoi

Introduction Stem cells have the remarkable potential to develop into many different cell types in the body during early life and growth. In addition, in many tissues they serve as a sort of internal repair system, dividing essentially without limit to replenish other cells as long as the person or animal is still alive. When a stem cell divides, each new cell has the potential either to remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell (Figure 1). Stem cells are easily distinguished from other cell types by two important characteristics. First, they are unspecialized cells capable of renewing themselves

through cell division, sometimes after long periods of inactivity. Second, under certain physiologic or experimental conditions, they can be induced to become tissue- or organ-specific cells with special functions. Until recently, scientists primarily worked with two kinds of stem cells from animals and humans: embryonic stem cells and non-embryonic "somatic" or "adult" stem cells. Scientists discovered ways to derive embryonic stem cells from early mouse embryos nearly 30 years ago, in 1981. The detailed study of the biology of mouse stem cells led to the discovery, in 1998, of a method to derive stem cells from human embryos and grow the cells in the laboratory. These cells are called human embryonic stem cells. The embryos used in these studies were created for reproductive purposes through in vitro fertilization procedures. When they were no longer needed for that purpose, they were donated for research with the informed consent of the donor. In 2006, researchers made another breakthrough by identifying



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conditions that would allow some specialized adult cells to be "reprogrammed" genetically to assume a stem cell-like state. This new type of stem cell, called induced pluripotent stem cells (iPSCs). Stem cells are important for living organisms for many reasons. In the 3- to 5-day-old embryo, called a blastocyst, the inner cells give rise to the entire body of the organism, including all of the many specialized cell types and organs such as the heart, lung, skin, sperm, eggs and other tissues. In some adult tissues, such as bone marrow, muscle, and brain, discrete populations of adult stem cells generate replacements for cells that are lost through normal wear and tear, injury, or disease. Given their unique regenerative abilities, stem cells offer new potentials for treating diseases such as diabetes, and heart disease. However, much work remains to be done in the laboratory and the clinic to understand how to use these cells for cell-based therapies to treat disease, which is also referred to as regenerative or reparative medicine.

Fig. 1: Stem Cells: The body’s master cells. All other cells arise from stem cells, including blood cells, nerve cells and others. Laboratory studies of stem cells enable scientists to learn about the cells’ essential

properties and what makes them different from specialized cell types. Scientists are already using stem cells in the laboratory to screen new drugs and to develop model systems to study normal growth and identify the causes of birth defects. Research on stem cells continues to advance knowledge about how an organism develops from a single cell and how healthy cells replace damaged cells in adult organisms. Stem cell research is one of the most fascinating areas of contemporary biology, but, as with many expanding fields of scientific inquiry, research on stem cells raises scientific questions as rapidly as it generates new discoveries. Potential uses of human stem cells There are many ways in which human stem cells can be used in research and the clinic. Studies of human embryonic stem cells will yield information about the complex events that occur during human development. A primary goal of stem cell research is to identify how undifferentiated stem cells become the differentiated cells that form the tissues and organs. Scientists know that turning genes on and off is central to this process. Some of the most serious medical conditions, such as cancer and birth defects, are due to abnormal cell division and differentiation. A more complete understanding of the genetic and molecular controls of these processes may yield information about how such diseases arise and suggest new strategies for therapy. Human stem cells could also be used to test new drugs. For example, new medications could be tested for safety on differentiated cells generated from human pluripotent cell lines.


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Fig. 2: Potential uses of Stem Cells in therapeutics Other kinds of cell lines are already used in this way. Cancer cell lines, for example, are used to screen potential anti-tumor drugs. The availability of pluripotent stem cells would allow drug testing in a wider range of cell types. The most important potential application of human stem cells is the generation of cells and tissues that could be used for cell-based therapies. Today, donated organs and tissues are often used to replace ailing or destroyed tissue, but the need for transplantable tissues and organs far outweighs the available supply. Stem cells, directed to differentiate into specific cell types, offer the possibility of a renewable source of replacement cells and tissues to treat diseases including Alzheimer's diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis, and rheumatoid arthritis (Figure 2). For example, it may become possible to generate healthy heart muscle cells in the laboratory and then transplant those cells into patients with chronic heart disease. Preliminary research in mice and other animals indicates that bone marrow stromal cells, transplanted into a damaged heart, can have beneficial effects. Whether

these cells can generate heart muscle cells or stimulate the growth of new blood vessels that repopulate the heart tissue, or help via some other mechanism is actively under investigation. For example, injected cells may accomplish repair by secreting growth factors, rather than actually incorporating into the heart. Promising results from animal studies have served as the basis for a small number of exploratory studies in humans. Other recent studies in cell culture systems indicate that it may be possible to direct the differentiation of embryonic stem cells or adult bone marrow cells into heart muscle cells (Figure 3). In people who suffer from type 1 diabetes, the cells of the pancreas that normally produce insulin are destroyed by the patient's own immune system. New studies indicate that it may be possible to direct the differentiation of human embryonic stem cells in cell culture to form insulin-producing cells that eventually could be used in transplantation therapy for persons with diabetes. To realize the promise of novel cell-based therapies for such pervasive and debilitating diseases, scientists must be able to manipulate stem cells so that they possess the necessary characteristics for successful differentiation, transplantation, and engraftment. To summarize, stem cells offer exciting promise for future therapies, but significant technical hurdles remain that will only be overcome through years of intensive research. Key research events on Stem Cells 1908 - The term "stem cell" was proposed for scientific use by the Russian histologist Alexander Maksimov (1874–1928) at congress of hematologic society in Berlin. It

http://stemcells.nih.gov/info/basics/basics6.asp#figure4

http://en.wikipedia.org/wiki/Russia

http://en.wikipedia.org/wiki/Alexander_Maksimov

http://en.wikipedia.org/wiki/Berlin


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postulated existence of haematopoietic stem cells

Fig. 3: Strategies to repair heart muscle with adult stem cells.

• 1960s - Joseph Altman and Gopal

Das present scientific evidence of adult neurogenesis, ongoing stem cell activity in the brain; like André Gernez, their reports contradict Cajal's "no new neurons" dogma and are largely ignored.

• 1963 - McCulloch and Till illustrate

the presence of self-renewing cells in mouse bone marrow.

• 1968 - Bone marrow transplant

between two siblings successfully treats SCID.

• 1978 - Haematopoietic stem cells are

discovered in human cord blood. • 1981 - Mouse embryonic stem cells

are derived from the inner cell mass by scientists Martin Evans, Matthew Kaufman, and Gail R. Martin. Gail Martin is attributed for coining the

term "Embryonic Stem Cell".

• 1992 - Neural stem cells are cultured in vitro as neurospheres.

• 1997 - Leukemia is shown to

originate from a haematopoietic stem cell, the first direct evidence for cancer stem cells.

• 1998 - James Thomson and

coworkers derive the first human embryonic stem cell line at the University of Wisconsin–Madison.

• 2000s - Several reports of adult stem

cell plasticity are published.

• 2001 - Scientists at Advanced Cell Technology clone first early (four- to six-cell stage) human embryos for the purpose of generating embryonic stem cells.

• 2003 - Dr. Songtao Shi of NIH

discovers new source of adult stem cells in children's primary teeth.

• 2004–2005 - Korean researcher

Hwang Woo-Suk claims to have created several human embryonic stem cell lines from unfertilised human oocytes. The lines were later shown to be fabricated.

• 2005 - Researchers at Kingston

University in England claim to have discovered a third category of stem cell, dubbed cord-blood-derived embryonic-like stem cells (CBEs), derived from umbilical cord blood. The group claims these cells are able to differentiate into more types of tissue than adult stem cells.

• 2005 - Researchers at UC Irvine's

http://en.wikipedia.org/wiki/Joseph_Altman

http://en.wikipedia.org/wiki/Neurogenesis

http://en.wikipedia.org/wiki/Andr%C3%A9_Gernez

http://en.wikipedia.org/wiki/Andr%C3%A9_Gernez

http://en.wikipedia.org/wiki/Santiago_Ram%C3%B3n_y_Cajal

http://en.wikipedia.org/wiki/Ernest_McCulloch

http://en.wikipedia.org/wiki/James_Till

http://en.wikipedia.org/wiki/Bone_marrow

http://en.wikipedia.org/wiki/Organ_transplant

http://en.wikipedia.org/wiki/Severe_combined_immunodeficiency

http://en.wikipedia.org/wiki/Haematopoietic_stem_cell

http://en.wikipedia.org/wiki/Cord_blood

http://en.wikipedia.org/wiki/Embryonic_stem_cell

http://en.wikipedia.org/wiki/Inner_cell_mass

http://en.wikipedia.org/wiki/Martin_Evans

http://en.wikipedia.org/wiki/Matthew_Kaufman

http://en.wikipedia.org/wiki/Matthew_Kaufman

http://en.wikipedia.org/wiki/Gail_R._Martin

http://en.wikipedia.org/wiki/In_vitro

http://en.wikipedia.org/wiki/Cancer_stem_cell

http://en.wikipedia.org/wiki/James_Thomson_%28cell_biologist%29

http://en.wikipedia.org/wiki/Stem_cell_line

http://en.wikipedia.org/wiki/University_of_Wisconsin%E2%80%93Madison

http://en.wikipedia.org/wiki/Adult_stem_cell

http://en.wikipedia.org/wiki/Adult_stem_cell

http://en.wikipedia.org/wiki/Advanced_Cell_Technology

http://en.wikipedia.org/wiki/Advanced_Cell_Technology

http://en.wikipedia.org/wiki/Hwang_Woo-Suk



http://en.wikipedia.org/wiki/Oocyte

http://en.wikipedia.org/wiki/Kingston_University

http://en.wikipedia.org/wiki/Kingston_University

http://en.wikipedia.org/wiki/England

http://en.wikipedia.org/wiki/UC_Irvine


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Reeve-Irvine Research Center are able to partially restore the ability of mice with paralyzed spines to walk through the injection of human neural stem cells.

• August 2006 - Rat Induced

pluripotent stem cells: the journal Cell publishes Kazutoshi Takahashi and Shinya Yamanaka.

• October 2006 - Scientists at

Newcastle University in England create the first ever artificial liver cells using umbilical cord blood stem cells.

• January 2007 - Scientists at Wake

Forest University led by Dr. Anthony Atala and Harvard University report discovery of a new type of stem cell in amniotic fluid. This may potentially provide an alternative to embryonic stem cells for use in research and therapy.

• June 2007 - Research reported by

three different groups shows that normal skin cells can be reprogrammed to an embryonic state in mice. In the same month, scientist Shoukhrat Mitalipov reports the first successful creation of a primate stem cell line through somatic cell nuclear transfer.

• October 2007 - Mario Capecchi,

Martin Evans, and Oliver Smithies win the 2007 Nobel Prize for Physiology or Medicine for their work on embryonic stem cells from mice using gene targeting strategies producinggenetically engineered mice (known as knockout mice) for gene research.

• November 2007 - Human induced pluripotent stem cells: Two similar papers released by their respective journals prior to formal publication: in Cell by Kazutoshi Takahashi and Shinya Yamanaka, "Induction of pluripotent stem cells from adult human fibroblasts by defined factors", and in Science by Junying Yu, et al., from the research group of James Thomson, "Induced pluripotent stem cell lines derived from human somatic cells" pluripotent stem cells generated from mature human fibroblasts. It is possible now to produce a stem cell from almost any other human cell instead of using embryos as needed previously, albeit the risk of tumorigenesis due to c-myc and retroviral gene transfer remains to be determined.

• January 2008 - Robert Lanza and

colleagues at Advanced Cell Technology and UCSF create the first human embryonic stem cells without destruction of the embryo.

• January 2008 - Development of

human cloned blastocysts following somatic cell nuclear transfer with adult fibroblasts.

• February 2008 - Generation of

pluripotent stem cells from adult mouse liver and stomach: these iPS cells seem to be more similar to embryonic stem cells than the previous developed iPS cells and not tumorigenic, moreover genes that are required for iPS cells do not need to be inserted into specific sites, which encourage the development of non-viral reprogramming techniques.

http://en.wikipedia.org/wiki/Induced_pluripotent_stem_cell


http://en.wikipedia.org/wiki/Cell_%28journal%29

http://en.wikipedia.org/wiki/Shinya_Yamanaka

http://en.wikipedia.org/wiki/Newcastle_University

http://en.wikipedia.org/wiki/Wake_Forest_University

http://en.wikipedia.org/wiki/Wake_Forest_University

http://en.wikipedia.org/wiki/Anthony_Atala

http://en.wikipedia.org/wiki/Anthony_Atala

http://en.wikipedia.org/wiki/Harvard_University

http://en.wikipedia.org/wiki/Amniotic_fluid

http://en.wikipedia.org/w/index.php?title=Shoukhrat_Mitalipov&action=edit&redlink=1

http://en.wikipedia.org/wiki/Somatic_cell_nuclear_transfer


http://en.wikipedia.org/wiki/Mario_Capecchi

http://en.wikipedia.org/wiki/Martin_Evans

http://en.wikipedia.org/wiki/Oliver_Smithies

http://en.wikipedia.org/wiki/Nobel_Prize_for_Physiology_or_Medicine

http://en.wikipedia.org/wiki/Nobel_Prize_for_Physiology_or_Medicine

http://en.wikipedia.org/wiki/Knockout_mice



http://en.wikipedia.org/wiki/Cell_%28journal%29

http://en.wikipedia.org/w/index.php?title=Kazutoshi_Takahashi&action=edit&redlink=1

http://en.wikipedia.org/wiki/Shinya_Yamanaka

http://en.wikipedia.org/wiki/Junying_Yu

http://en.wikipedia.org/wiki/Junying_Yu

http://en.wikipedia.org/wiki/James_Thomson_%28cell_biologist%29

http://en.wikipedia.org/wiki/Tumorigenesis

http://en.wikipedia.org/wiki/C-myc

http://en.wikipedia.org/wiki/Gene_therapy#Retroviruses



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• March 2008-The first published study of successful cartilage regeneration in the human knee using autologous adult mesenchymal stem cells is published by clinicians from Regenerative Sciences.

• October 2008 - Sabine Conrad and

colleagues at Tübingen, Germany generate pluripotent stem cells from spermatogonial cells of adult human testis by culturing the cells in vitro under leukemia inhibitory factor (LIF) supplementation.

• October 2008 - Embryonic-like stem

cells from a single human hair.

• March 2009 - Andras Nagy, Keisuke Kaji, et al. discover a way to produce embryonic-like stem cells from normal adult cells by using a novel "wrapping" procedure to deliver specific genes to adult cells to reprogram them into stem cells without the risks of using a virus to make the change The use of electroporation is said to allow for the temporary insertion of genes into the cell.

Key References on Stem Cells: • Thomson J, Itskovitz-Eldor J,

Shapiro S, Waknitz M, Swiergiel J, Marshall V, Jones J (1998). "Embryonic stem cell lines derived from human blastocysts". Science 282 (5391): 1145–1147.

• Takahashi K, Yamanaka S (2006). "Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors". Cell 126 (4): 663–676.

• Takahashi K, Tanabe K, Ohnuki M, Narita M, Ichisaka T, Tomoda K, Yamanaka S (2007). "Induction of pluripotent stem cells from adult human fibroblasts by defined factors" Cell 131 (5): 861–872.

For a more detailed discussion of stem cells, follow the websites:

• http://stemcells.nih.gov/info/basics/ • http://www.nlm.nih.gov/medlineplus

/stemcells.html • http://www.isscr.org/public

http://www.explorestemcells.co.uk http://www.stemcellresearchnews.com

The author is working as a Research Associate at Howard Hughes Medical Institute, Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093

Email : [email protected] Prafulla Chandra Roy managed to synthesize NH4NO2 in its pure form, and became the first scientist to have done so. Prior to Ray’s synthesis of Ammonium nitrite it was thought that the compound undergoes rapid thermal decomposition releasing nitrogen and water in the process. He also discovered the compound

mercurous nitrate in 1896. The discovery contributed as a base for significant future research in the field of chemistry. He published his discoveries in the “Journal of Asiatic Society of Bengal”. He was the founder of “Bengal Chemicals and Pharmaceuticals”, India’s first Pharmaceutical company.

http://en.wikipedia.org/wiki/Pluripotent_stem_cells

http://en.wikipedia.org/wiki/Leukemia_inhibitory_factor

http://en.wikipedia.org/wiki/Electroporation

http://images.cell.com/images/Edimages/Cell/IEPs/3661.pdf




http://stemcells.nih.gov/info/basics/

http://www.nlm.nih.gov/medlineplus/stemcells.html

http://www.nlm.nih.gov/medlineplus/stemcells.html

http://www.isscr.org/public/

http://www.explorestemcells.co.uk/

http://www.stemcellresearchnews.com/

http://www.stemcellresearchnews.com/



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Coffee: The most popular beverage Progyashree Goswami History An Arabian shepherd named Kaldi found his goats dancing joyously around a dark green leafed shrub with bright red cherries in the southern tip of the Arabian Peninsula. Kaldi soon determined that it was the bright red cherries on the shrub that were causing the peculiar euphoria and after trying the cherries himself, he learned of their powerful and stimulus effect. This way Coffee was born in Arab and Ethiopia during 850- 900 Christian Era (C.E.) and became today’s worldwide most popular beverage. South America (Brazil) is in the 1st rank in coffee production.

Introduction The word coffee is believed to be derived from Chaoua (English), Caffé (Italian), Kaffa (Ethiopia) etc. The shrub species of the genus Coffea produce green then red color berries from which coffee is extracted. Three major steps needed to prepare the green beans for consumption are (1) beans must be roasted 8-12 minutes and finally reach a temperature of 210–225 °C, (2) then coffee must be ground relative to how it will be brewed and (3) the freshly roasted and freshly ground coffee must be brewed at the

right temperature for the correct amount of time.

The Chemistry Coffee Acidity The pH of coffee is found to be acidic and may be broadly classified into three groups: aliphatic, chlorogenic, and alicyclic carboxylic and phenolic acids. Roasted coffee contains (a) volatile and, (b) non-volatile aliphatic carboxylic acids, (c) heterocyclic furanoid carboxylic acid, (d) chlorogenic, (e) alicyclic and phenolic, (f) inorganic acids. Lactic, Acetic, Citric, Maleic, Phosphoric, Quinic, Clorogenic, Palmitic, Linoic acid are some of the major ingredients. Caffeine is found to be the principal stimulating ingredient.

http://en.wikipedia.org/wiki/Coffea


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Coffee Aroma Coffee aroma is responsible for all coffee flavor, sweet, salt, bitter, and sour taste. Near 800 volatile aromatic compounds are discovered today and they are responsible for different tastes. Recent reviews emphasized that chemists have identified 150 aliphatic compounds including 56 carbonyl compounds and 9 sulfur containing compounds; 20 alicyclic compounds, including 10 ketones; 60 aromatic benzenoid compounds, including 16 phenols; 300 heterocyclic compounds, including 74 furans, 10 hydrofurans, 37 pyrroles, 9 pyridines, 2 quinolines, 70 pyrazines, 10 quinoxalines, 3 indoles, 23 thiophens, 3 thiophenones, 28 thiazoles, and 28 oxazoles in coffee bean. A recent report by Müller and Hoffman from Germany on the complex chemistry that occurred in coffee roasting is presented in the following scheme, © American Chemical Society. β-damascenone (like cooked apples), 2-furfurylthiol (sulfury, roasty), 2-isobutyl-3-methoxypyrazine (earthy), guaiacol (spicy), 2,3-butanedione (buttery), and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like), (E)-damascenone (honey like), 3-Mercapto-3-methylbutylformate (catty), 3-Methyl-2-buten-1-thiol (amine like), 4-Vinylguaiacol (spicy), Vanillin (vanilla), 2,3-Pentanedione (buttery) etc. are the most influential components in coffee for its aroma. Decaffeination Decaffeination is the process by which most of relatively harmful ingredients to our health are removed and to enhance coffee quality. This consists of soaking the beans in water to dissolve the caffeine, extracting the caffeine with either a solvent (methylene chloride, ethyl acetate etc.) or activated carbon, and then re-soaking the coffee beans in the decaffeinated water to reabsorb the

flavor compounds that were lost in the initial extraction. The principle based on equilibrium and solvent/ solute properties. Three major decaffeination processes are (i) Swiss water process, (ii) CO2 process, (iii) Sparkling water process.

Coffee Bitter Taste The bitter taste from coffee is directly dependent to the extent of extraction which is correlated upon the roast, the mineral content of the water, water temperature, time, grind size, and brewing procedure. Caffeine has a distinct bitter taste and has a test threshold of only 75-155 mg/L. Robusta coffee contains higher levels of both caffeine and chlorogenic acids, which are partly responsible for bitterness and astringency in coffee. Bitterness of caffeine may be weakened when polyphenols are introduced. Astringent and metallic tastes in coffee have been attributed to dicaffeoylquinic acids. Trigonelline is


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perceived as bitter at concentrations of 0.25%, whereas chlorogenic acids necessitate a concentration of 0.4% at pH of 5 to be perceived as bitter. Trigonelline degradation is proportional to roast degree. Its byproducts include pyridines, which are said to contribute a roasty aroma to the coffee. Quinic acid, a degradation product of chlorogenic acids is present at twenty times its threshold value and is partly responsible for the perceived bitterness in coffee. Furfuryl alcohol is thought to contribute a burnt and bitter taste to coffee. Coffee Side Effects A list of most harmful side effects of caffeine complied from Google is 1. Caffeine makes heart beat abnormally fast. 2. Caffeine compresses the blood vessels in brain causing massive headaches. 3. Caffeine is a strong diuretic causing body to become dehydrated. 4. Due to over-activation of the central nervous system (CNS) sometime people experience tremors after drinking caffeine. 5. Women who drink one cup of coffee every day has only half chance to be able to get pregnant as those who drink no coffee. If 2 cup a day it is 5 times less chance. 6. Caffeine can cause tension or stiffness in your neck, shoulders, jaw, hands, legs or stomach. 7. It can cause mood swings or periods of depression during the day 8. Caffeine can cause coldness in hands and feet because it restricts circulation.

References 1. http://www.coffeeresearch.org 2. http://www.wikipedia.org 3. Coffee: The Chemistry of Quality. 107-110. 4. The Flavour of Coffee. In Development of Food Science. 3B: 1-47. 1986. 5. Food Chemistry, 1987, 26, 59-69 6. Environmental Health Perspectives, 2007, 115.9, A456-A459. The author is a Research Scholar at Natural Product Division, NEIST, Jorhat, Assam. Email:[email protected] ------------------------------------------------------

http://www.coffeeresearch.org/

http://www.wikipedia.org/


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Circular Dichroism: An excellent technique for determination of absolute configuration Pori Buragohain Knowledge of absolute configuration of asymmetric, chiral carbon atom is essential for the understanding of enzyme mechanism, drugs action, structure –function relations, as well as determination of biological structure. Without the knowledge of absolute configuration, it is not possible to discover or develop a drug. Also it plays a crucial rule in drugs registration. In general determination of absolute configuration is achieved using single crystal x-ray analysis making use of anomalous dispersion. Difficulty arises when crystal is not of suitable quality. But using circular dichroism technique absolute configuration could be determined easily in solution. Circular dichroism (CD) refers to the differential absorption of left and right circularly polarized light. Electromagnetic radiation consists of an electric and magnetic field that oscillate perpendicular to one another and to the propagating direction. While linearly polarized light occurs when the electric field vector oscillates only in one plane and changes in magnitude, circularly polarized light occurs when the electric field vector rotates about its propagation direction and retains constant magnitude. Hence, it forms a helix in space while propagating. For left circularly polarized light (LCP) with propagation towards the observer, the electric vector rotates counterclockwise. For right circularly polarized light (RCP), the electric vector rotates clockwise.

When circularly polarized light passes through an absorbing optically active medium, the speed between right and left polarizations differ (cL ≠ cR) as well as their wavelength (λL ≠ λR) and the extent to which they are absorbed (εL≠εR). Circular dichroism is the difference ∆ε ≡ εL- εR. The electric field of a light beam causes a linear displacement of charge when interacting with a molecule (electric dipole), whereas the magnetic field of it causes a circulation of charge (magnetic dipole). These two motions combined cause an excitation of an electron in a helical motion, which includes translation and rotation and their associated operators. The experimentally determined relationship between the rotational strength (R) of a sample and the ∆ε is given by

http://en.wikipedia.org/wiki/Circular_polarization

http://en.wikipedia.org/wiki/Light

http://en.wikipedia.org/wiki/Electromagnetic_radiation

http://en.wikipedia.org/wiki/Polarization_%28waves%29

http://en.wikipedia.org/wiki/Helix

http://en.wikipedia.org/wiki/File:Linearly_pol.png

http://en.wikipedia.org/wiki/File:Linearly_pol.png

http://en.wikipedia.org/wiki/File:Circularly_pol.png

http://en.wikipedia.org/wiki/Wavelength

http://en.wikipedia.org/wiki/Electric_dipole

http://en.wikipedia.org/wiki/Magnetic_dipole

http://en.wikipedia.org/wiki/Electron

http://en.wikipedia.org/wiki/Translation

http://en.wikipedia.org/wiki/Rotation

http://en.wikipedia.org/wiki/Operators

http://en.wikipedia.org/w/index.php?title=Rotational_strength&action=edit&redlink=1


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The rotational strength has also been determined theoretically,

We see from these two equations that in order to have non-zero ∆ε, the electric and magnetic dipole moment

operators ( and

) must transform as the same irreducible representation. Cn and Dn are the only point groups where this can occur, making only chiral molecules CD activeSimply, since circularly polarized light itself is "chiral", it interacts differently with chiral molecules. That is, the two types of circularly polarized light are absorbed to different extents. In a CD experiment, equal amounts of left and right circularly polarized light of a selected wavelength are alternately radiated into a (chiral) sample. One of the two polarizations is absorbed more than the other one, and this wavelength-dependent difference of absorption is measured, yielding the CD spectrum of the sample. Due to the interaction with the molecule, the electric field vector of the light traces out an elliptical path after passing through the sample. So, optically active chiral molecules display this technique. CD spectroscopy has a wide range of applications in many different fields, means in UV, VIS, near IR and IR regions. Among these only vibrational circular dichroism, which uses light from the infrared energy region, is used for structural studies of small organic molecules, and most recently proteins and DNA. Recently, commercial VCD spectrometer becomes available. Vibrational circular dichroism (VCD) is a spectroscopic technique which

detects differences in attenuation of left and right circularly polarized light passing through a sample. It is basically circular dichroism spectroscopy in the infrared and near infrared ranges. Because VCD is sensitive to the mutual orientation of distinct groups in a molecule, it provides three-dimensional structural information. Thus, it is a powerful technique as VCD spectra of enantiomers can be simulated using ab initio calculations, thereby allowing the identification of absolute configurations of small molecules in solution from VCD spectra. Among such quantum computations of VCD spectra resulting from the chiral properties of small organic molecules are those based on density functional theory (DFT) and gauge-invariant atomic orbitals (GIAO). As a simple example of the experimental results that were obtained by VCD are the spectral data obtained within the carbon-hydrogen (C-H) stretching region of 21 amino acids in heavy water solutions. Measurements of vibrational optical activity (VOA) have thus numerous applications, not only for small molecules, but also for large and complex biopolymers such as muscle proteins (myosin, for example) and DNA. For biopolymers such as proteins and nucleic acids, the difference in absorbance between the levo- and dextro- configurations is five orders of magnitude smaller than the corresonding (unpolarized) absorbance. Therefore, VCD of biopolymers requires the use of very sensitive, specially built instrumentation as well as time-averaging over relatively long intervals of time even with such sensitive VCD spectrometers. Most CD instruments produce left- and right- circularly

http://en.wikipedia.org/wiki/Group_theory

http://en.wikipedia.org/wiki/Point_groups

http://en.wikipedia.org/wiki/Chirality_%28chemistry%29

http://en.wikipedia.org/wiki/Spectroscopy

http://en.wikipedia.org/wiki/Vibrational_circular_dichroism

http://en.wikipedia.org/wiki/Infrared

http://en.wikipedia.org/wiki/Spectroscopy

http://en.wikipedia.org/wiki/Circular_polarization

http://en.wikipedia.org/wiki/Circular_dichroism

http://en.wikipedia.org/wiki/Infrared

http://en.wikipedia.org/wiki/Density_functional_theory

http://en.wikipedia.org/wiki/Gauge-invariant

http://en.wikipedia.org/wiki/Atomic_orbitals

http://en.wikipedia.org/wiki/Amino_acid

http://en.wikipedia.org/wiki/Heavy_water

http://en.wikipedia.org/wiki/Myosin

http://en.wikipedia.org/wiki/DNA


39

polarized light which is then either sine-wave or square-wave modulated, with subsequent phase-sensitive detection and lock-in amplification of the detected signal. In the figure below, a schematic overview of the instrument is given. Infrared light is passed through a linear polariser to generate a linearly polarised light. A photo-elastic modulator subsequently converts it a left and right circularly polarised light. The light is then passed through the selected sample (a liquid or solution) and then finally to the detector. The VCD signal is then demodulated with a lock-in amplifier tuned to the PEM modulation frequency. Simultaneously both IR and VCD spectra are obtained.

To determine the absolute configuration of a molecule the following steps are taken 1. The experimental VCD spectrum is measured. 2. The VCD of one of the enantiomers is stimulated using ab initio DFT methods. The spectrum of other enantiomer is obtained by reversing the signals for the VCD bands, or calculating the VCD of mirror image structure (opposite enantiomer). 3. The experimental spectrum is then compared with the two stimulated spectra to see which enantiomer gives the best correlation between sign and intensities. At last we can conclude VCD is an excellent technique for the determination of the absolute configuration and conformation of small and medium sized molecules in solution. Increase in computer calculation speed will result in an extension of this technique to larger and more flexible molecules and will allow more efficient calculation of VCD spectra. The author is a Research Scholar at Natural Product Division, NEIST, Jorhat, Assam.

The eye cataract surgery was known to Indian physician Sushruta in 6 th century BCE. Traditional cataract surgery was performed with a special tool called the Jabamukhi Salaka, a curved needle used to loosen the lens and push the cataract out of the field of vision. The eye would later be soaked with warm butter and then bandaged. Greek philosophers and scientists

traveled to India where these surgeries were performed by physicians. The Sushruta Samhita contains 184 chapters and description of 1120 illnesses, 700 medicinal plants, a detailed study on Anatomy, 64 preparations from mineral sources and 57 preparations based on animal sources.


40

Thesis Synopsis STRUCTURAL AND THERMAL ANALYSIS OF ORGANIC SOLIDS Dr. Bipul Ch. Sarma Supervisor: Prof. Ashwini Nangia School of Chemistry, University of Hyderabad, India CHAPTER 1: Crystal Engineering Crystal engineering relies on non-covalent bonding in the solid state with desired properties and functions mainly focused on the use of more directional hydrogen bonds. It is the synthesis of supramolecular structures in the solid state which has now become an interdisciplinary subject dealing with the self-assembly of molecular crystals using hydrogen bonding, electrostatics, π-stacking, halogen bonding, van der Waals interactions, and metal-coordination bonding. The Cambridge Structural Database (CSD) provides an excellent tool for accessing the efficiency and reproducibility of a particular supramolecular synthon. This subject deals with various solid forms like polymorphs, host-guest complexes, network solids, salts, hydrates, cocrystals, more preferably pharmaceutical cocrystals. The ability of a compound to exist in more than one crystalline modification is polymorphism, a phenomenon with tremendous importance in pharmaceutical development and materials science as it can alter physical and chemical properties. Different types of polymorphism like conformational, synthon, packing polymorphism etc. could be possible for all kinds of molecules. However

the exact molecular features for a compound for it to be polymorphic are still elusive. Among the various analytical methods used for the characterization of polymorphs, thermal analysis (i.e. differential scanning calorimetry, thermogravimetry, hot stage microscopy), spectroscopy (FT-IR, NIR, Raman etc.), in-situ variable temperature powder X-ray diffraction and finally single crystal X-ray diffraction have received considerable attention. Thermal relation among kinetic/thermodynamic polymorphs, such as enantiotropic or monotropic, and their stability must be understood. Understanding the recurrence of more than one molecule or conformation (i.e. Z' > 1) in the crystal lattice is currently being an active topic for chemists and crystallographers. Our study shows higher probability of occurrence of Z′ > 1 structure using high temperature crystallization methods: melt and sublimation. Apart from polymorphs and hydrate structures, organic salts and cocrystals can show effective advantages over neutral APIs. Cocrystal is a multi-component crystal structure in which two or more compounds coexist through hydrogen bonds or non-covalent interactions. If the reactants are solids at ambient conditions, the multi-component crystalline materials are cocrystals and those composed of one or more solids and a liquid are known as solvates or pseudopolymorphs. The multi-component system is known as “molecular salt” or “organic salt” if proton is transferred from acid to base in ionic state. Common problems encountered with Active


41

Pharmaceutical Ingredients (APIs), in terms of their solubility, dissolution rates, and stability can be solved by making salt, cocrystal etc. without the need to make or break covalent bonds. The rational construction of novel open-framework organic solids has received particular interest because of their diverse applications such as chemical separation, drying agents, reactions and catalysis in a microcavity and for electro optic, nonlinear and magnetic materials. Hydration of molecules in the crystal structure is a common phenomenon, especially in pharmaceuticals. CHAPTER 2: Conformational and Synthon Polymorphism in Host Compounds 1,1-Bis-(4-hydroxyphenyl)cyclohexane (1) is a very good host molecule. The pure host form was never crystallized. The gust-free form of 1 was successfully isolated as two polymorphs using solvent less crystallization techniques: melt and sublimation. However several solvents were attempted, only solvent inclusion crystals or ill-defined powders were obtained. These techniques are further employed to generate new polymorphs of isomeric dihydroxybenzoic acids (2, 3, 4, 5, 6, and 7). All these compounds are highly prone to give solvate/hydrate forms upon solvent crystallization. Two polymorphs of 3,5-dihydroxybenzoic acid (2), a new polymorph of 2,3-dihydroxybenzoic acid (3) and guest free form of 3,4-dihydroxybenzoic acid (4) were crystallized by melting and sublimation. A new hydrate polymorph of 3,4-dihydroxybenzoic acid was isolated along with tetrahydrofuran, acetylacetone and dioxane solvates of 3,5-dihydroxybenzoic acid (2•THF,

2•Acac and 2•Diox) to confirm that they are prone to form solvates. 5, 6 and 7 gave either decomposed polyphenols or reported forms in the literature.

OH OH

OHOH

COOHOH

OH

COOH

OH

OH

COOH

OHOH

COOHOH

OH

COOHOH

OH

COOH

1

2 3 4

5 6 7

Fig. 1: Popular hosts. They were successfully treated to melt and sublimation to find a new guest-free form or a new polymorph. Polymorphs of 1 differ in the conformations of OH groups which lead to the difference in molecular arrangement in crystalline lattice. Polymorphs of isomeric dihydroxybenzoic acid differ in nature of hydrogen bond synthons in their crystal structures however two hydrate polymorphs of 4 show differences in packing. Two solvent free methods to obtain guest free forms of molecules that are prone to give solvent/water included structures on crystallization were investigated. These methods show potential to generate new polymorphic modifications. Phase transition from metastable to stable polymorph was explained in detail by differential scanning calorimetry (DSC), hot stage microscopy (HSM) and hydrogen bonding changes in 1. CHAPTER 3: High Z′ Structures by Solvent Less Methods Crystal structures with multiple Z' (= number of molecules in the asymmetric unit) are now being intensely studied to understand the factors leading to high Z′ crystal structures. A Cambridge Structural Database (CSD) search on structures


42

crystallized using solvent free methods such as melt and sublimation was carried out. It is found that solvent-free crystallization methods show a much higher probability of multiple Z' structures compared to overall CSD trends on Z' frequencies. Crystal structure having Z' > 1 is <12%. Generation of high Z' structures by melting and sublimation crystallization can be understood as rapid cooling of the hot liquid or vapor in the open flask or on the cold finger is a kinetic phase and the conditions under which hydrogen-bonded clusters are likely to condense in a pseudo-symmetric crystalline arrangement. 1,1-bis-(4-hydroxyphenyl)cyclohexane is a remarkable example to illustrate how close packing conflicts in a metastable Z' = 2 structure are resolved in the thermodynamic Z' = 1 polymorph. CHAPTER 4: Polymorphism and Phase Transition in Phenylbenzenesulfonamides A thorough screening for all the possible polymorphs is considered an essential step in pharmaceutical industry to choose the best drug formulation with desirable properties. The original antibacterial sulfonamides i.e. sulfa drugs are synthetic antimicrobial agents (sulfathiazole, sulfapyridine, sulfadiazine etc.) that contain the sulfonamide functionality (primary or secondary). Our objective is to compare molecular packing, nature of different types of non-covalent interaction like hydrogen bonds, and halogen interactions, isostructurality of polymorphs and more important solvent effect on polymorphism and complete spectroscopic analysis. A systematic study on polymorphism gives insight into structural relationship and the

mechanism of phase transition between crystalline modifications.

N

Y

H S O

O

X

z

NH S O

O

X

Y

NH S O

O

Y

z

X

8. X=H, Y=Z=CH39. X=Y=Z=CH310. Z=Y=Cl, X=CH311. Z=Y=CH3, X=Cl12. X=Z=Cl, Y=CH313. X=H, Y=Z=Cl

14. X=Cl, Y=CH315. X=Y=CH316. X=Y=Cl17. X=CH3, Y=Cl

18. X=CH3, Y=H, Z=F19. X=Y=CH3, Z=F20. X=Y=CH3, Z=Cl

S

OO

N

H

SO

NH

O

SO

NH

O

SO

NH

O

SO

N

O

HS

O

NH

O

Dimer MotifFlexible Torsions

Catemer Motif

Fig. 2:(a) Phenylbenzenesulfonamides, (b) Torsion flexibility, dimer or catemer hydrogen bond. Six molecules from a set of thirteen (8–20) are found to be polymorphic and all are well characterized by powder X-ray diffraction, single crystal X-ray diffraction, thermal analysis, hot stage microscopy, Raman, FT-IR, NIR spectroscopy, manual heating/grinding experiment etc. Phase transition from metastable to stable polymorph was examined by HSM and DSC in two systems further confirmed by powder X-ray pattern and unit cell parameter determination. N−H···O catemer and dimer motif of sulfonamide group (Figure 2b) is seen as the main difference in two systems (8 and 10) however C−H···O, C−H···π, C−H···X, Cl···Cl interaction play a role in differentiating other polymorphic systems. Solvent plays significant role


43

in the nucleation of polymorphic crystals. CHAPTER 5: Tetrahedral and H-shaped Host Tectons Porous architectures and network solids have important applications. Tetraphenyl methanes and silanes with boronic acid group have the potential of exchange in guest inclusion and predictable porous architetures includes guest species to the extent of 60-65% in inter-connected channels. Tetraphenylmethane tetrasulfonic acid was synthesized (TPM-SO3H, 21, Figure 3a) and crystallized from MeOH to analyze structural and thermal behavior as the structural chemistry of sulfonic acid group has not been explored in tetrahedral molecules. Colorless needle-shaped crystals of TPM-SO3H crystallized in tetragonal space group I4(1)/a contains ¼ TPM-SO3H molecule and 3 water molecules in its asymmetric unit giving a host: guest ratio of 1:12 (Figure 3b). TGA and X-ray crystal structure are consistent with 1:12 host: water stoichiometry (observed: 25.41%, calculated: 25.23%, Figure 3c). Two endothermic steps in DSC show water is lost in two stages. TPM-SO3H can reversibly uptake water from atmosphere. This loss/reuptake of water is quantitative and selective in successive cycles (Figure 3d). Compounds having properties of reversible, quantitative and selective uptake of water/solvent can have potential applications in dehydrating agents and organic zeolites. H-shaped molecule 1,4-di[bis(4'-hydroxyphenyl)methyl]benzene (22) and its octamethyl derivative (23) were synthesized (Figure 4) and crystallized in solvated and guest-free forms to analyze the occurrence of specific network architectures

SO3H

SO3H

SO3H

SO3H

Fig. 3: (a) Tetrakis(4-sulfo phenyl) methane (21). (b) Two types of water molecules are sitting in square (red) and irregular interconnected channels (pink) in the crystal structure

Fig. 3: (c) DSC and TGA curves of TPM-SO3H. The values are in accordance with the X-ray crystal structure. (d) Water loss and uptake is reversible in 3 successive cycle in TGA.


44

O

OH

OH

O

OH

OHOH

OH

OH

OH

R

R

R

RR

R

R

R22: R = H23: R = CH3

H shape

Fig. 4: Simple H-shaped molecule and octamethyl derivative (22 and 23) are synthesized and crystallized in solvated and guest free form. 22• CH3NO2 and 23• CHCl3 show rare

pentagonal (5,34 ) net.

Doubly interpenetrated 1D ladder is observed in the guest-free form of 22. Crystallization of 22 from CH3NO2 with varying amount of CF3CH2OH afforded two CH3NO2 solvate polymorphs as plate-shaped crystals in space group Pbca and block crystals in space group P21/c having different network topologies. Pbca form shows polycatenated porous hexagonal sheets with degree of catenation 2/2. However P21/c polymorph shows rare

pentagonal layer tiling of (5,34 ) nets

extending in third dimension. Molecule 23 upon crystallization from CHCl3 solvents also afforded the same rare

(5,34 ) net of contiguous pentagons in

2D sheet. The tetrahedral carbon centers are 3-connected nodes and hydrogen bonding OH groups are 4-center nodes of congruent cyclopentanoid rings. The first examples of pentagon layer tiling in a lattice inclusion organic host are reported. CHAPTER 6: Synthon Competition and Cooperation in Cocrystals and Salts Hydrogen bond synthon competition and cooperation was studied when four functionalities: carboxylic acid,

pyridine, amine, and hydroxyl are simultaneously present in the supramolecular system. Isomeric and substituted hydroxybenzoic acids and isomeric aminopyridines were selected to prepare 11 cocrystals from methanol solvent (Figure 5) and their structures were characterized by X-ray diffraction. OH

COOH

N

NH2

N

NH2

COOH

OH

COOH

OHOHOH

COOH

F

OH

COOH

Cl

OH

COOH

MeMe

24: 4-HBA.4-AP.H2O (1:1:1)25: 4-HBA.3-AP (1:1)26: 3-HBA.4-AP (1:1)27: 3,5-DiHBA.3-AP (1:1)28: 3-F-4-HBA.4-AP.H2O (1:1:1)29: 3-F-4-HBA.3-AP (1:1)30: 3-Cl-4-HBA.4-AP.H2O (1:1:1)31: 3-Cl-4-HBA.3-AP (1:1)32: 3,5-DiMe-4-HBA.4-AP.H2O (1:1:1)33: 3,5-DiMe-4-HBA.3-AP (1:1)34: 2(3,5-DiHBA).3-AP (2:1)

4-HBA

4-AP 3-AP

3-HBA 3,5-DiHBA 3-F-4-HBA 3-Cl-4-HBA 3,5-DiMe-4-HBA

Fig. 5: Hydroxybenzoic acids (HBA) cocrystallized with aminopyridines (AP) and the resulting organic salt composition (24-34). Four are hydrate (24, 28, 30, 32) structures. Proton transfer from COOH to pyridyl N acceptor (PyN) occurred in all 11 molecular salts (24-34) leading to a PyNH+···–OOC ionic synthon in 10 structures (24-33) and PyNH+···O=C hydrogen bond in 34. The observed hydrogen bonds were analyzed between COO–, OH, NH2, PyNH+, and H2O functional groups in these 11 structures, of which 4 are hydrates (24, 28, 30, 32). Synthons in this study are compared with statistics extracted from the Cambridge Structural Database to summarize trends and predict hydrogen bonding in new cocrystal and salt structures. We show that hydrogen bonding functional groups such as OH and NH2 promote persistent formation of ionic PyNH+···–OOC synthon in the same supramolecular system. However the ∆pKa rule for predicting neutral or ionic O-H···N/N+–H···O– hydrogen bonds is found to be inadequate in this system. Even as bioavailability of a drug is intimately related to its formulation; neutral (cocrystal) or


45

ionic (salt), there is no easy way to know the answer before structure determination. CHAPTER 7: Conclusion and Future Prospects The immense importance of polymorphism in the formulation of APIs is because they can alter the physical and chemical properties. Therefore it is crucial to screen for all possible polymorphs of a drug and chose the right one, preferably the most stable polymorph with desirable properties for product formulation after a complete thermal profile. Melt and sublimation crystallization are used to generate guest-free host structures and polymorphs. Stability relationship of the two conformational polymorphs of 1 is established. Melt crystallization and sublimation are likely to give high Z′ structures. Our results were compared with overall Z′ frequencies in CSD statistics. A series of secondary sulfonamide molecules were synthesized and screened and found six polymorphic systems from solvent crystallization and melting. Solid to solid state phase transition was observed and confirmed by spectroscopic techniques and thermal analysis. An organic host tetraphenylmethane tetraphenylsulfonic acid was synthesized and detail structural and thermal analysis was carried out. This compound shows reversible and selective guest release and uptake properties that can have potential application in organic zeolite and in dehydrating agents. The organic phenol host 1,4-di[bis(hydroxyphenyl) methyl]benzene and its octamethyl derivative were synthesized and crystallized in solvated and guest free forms. Supramolecular network includes interpenetrated ladders,

polycatenated (6,3) net, rare

pentagonal (5,34 ) net are observed.

Important biological phenomenon of proton transfer dependence on pKa and functional groups present on salt formation was carried out by studying a set of 11 molecular salts between isomeric hydroxybenzoic acid and isomeric amino pyridines. Cocrystals, pharmaceutical cocrystals, salts, hydrates are also having substantial importance in pharmaceutical industry to modify the properties of drugs. Salts and cocrystals have the potential to be much more useful in pharmaceutical products than solvates or hydrates because the number of pharmaceutically acceptable solvents is very small, and moreover solvents tend to undergo dehydration/desolvation in the solid dosage forms. Crystal engineering has significant contribution and overlap with like organic chemistry, inorganic chemistry, supramolecular chemistry, X-ray crystallography, materials research, computational chemistry and pharmaceutical chemistry and in current times it is moving from structure design to functional control. Selected Publications [1] Appl. Organometal. Chem. 2004,

18, 440–445. [2] Chem. Commun. 2006, 4918–

4920. [3] CrystEngComm 2007, 9, 628–631. [4] Mettler Toledo Thermal Analysis

Newsletter, 2007, 1, 9–13. [5] Cryst. Growth Des. 2008, 8,

1471–1473. [6] Acta Cryst. 2008, A64, C449. [7] Cryst. Growth Des. 2008, 8,

4546–4552. [8] Cryst. Growth Des. 2009, 9,

1546–1557 [9] New J. Chem. 2010, 34, 623–636.


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[10] Cryst. Growth Des. 2010, 10, 2388–2399.

[11] J. Pharm. Sci. 2010 (In Press) [12] Cryst. Growth Des. 2010 (In

Press) [13] Book Chapter: Inclusion

Phenomenon in Phenol Host © Nova Science Publishers, Inc. USA, 2010.

Thesis Synopsis

INVESTIGATIONS ON HIGH DENSITY HOLOGRAPHIC DATA STORAGE AND CONTENT-ADDRESSABLE SEARCH Dr. Bhargab Das

1.1 Introduction

Owing to the continuous expansion of the internet and digital communications, the field of data storage is facing challenging and complex demands for new and improved storage technologies that provide higher capacities, higher transfer rates, and shorter data access times than the current storage products. There is also demand for storage in different areas of science such as, in storing the huge image files generated by astronomical telescopes, in handling the data of high energy physicists, and in the field of bioinformatics. At the same time, both the magnetic and the conventional optical data storage technologies, where the individual bits are stored as distinct magnetic and optical changes on the surface of the recording medium, are approaching physical limits beyond which individual bits may be too small or too difficult to store. Holographic data storage (HDS) systems, where information is stored throughout the

The author is presently working as a Postdoctoral Fellow at Illinois Institute of Technology, Chicago, IL, USA. He will move to MIT, Boston along with his Prof from September, 2010.

Email : [email protected]

volume of a medium (not just on its surface), are envisioned as a possible answer to the next generation of high speed and large capacity storage devices. It promises huge storage densities (> 500 GB in a 120 mm disc), fast data transfer rates (> 10 Gb/s), extremely short data access times (< 50 µs), and tremendous search capabilities for finding unindexed information in databases (> 100 Gb/s). As the insatiable demand for more storage capacity persists unabated, optical data storage continues to play a dominant role. Some of the major advantages that optical storage offers over other main-stream data storage technologies, such as magnetic disc systems and solid state memories (flash memories), are capacity, removability, long life time of the data medium, and the ability to mass-produce media for content distribution, maintaining low cost per GByte. Since the invention of holography, the possibility of storing information by using holographic techniques has fascinated many researchers. Earlier works were focused primarily on analog images and pictures. The introduction of holographic channel codes and the digital signal processing in holography opened a new paradigm, holographic data storage. Although conceived decades ago, HDS has made


47

recent progress towards practicality, primarily because of the rapid technological advancements in various optoelectronic components such as spatial light modulators (SLM), charged-coupled devices (CCD), complimentary metal-oxide semiconductors (CMOS), and the development of high optical quality and low shrinkage photopolymer recording materials. In the past few years, researchers have demonstrated experimentally a data density as high as 350 Gbits/sq. in. and a sustained optical data transfer rate as high as 10 Gbits/s separately in different optical systems. These scientific and research progresses made in the last few years are expected to make HDS systems as commercially viable in the near future. Once such a system is commercially realized as a portable device, this technology has the potential to outperform any contemporary optical storage technologies such as DVD (Digital Versatile Disc) or BD (Blu-ray Disc).

1.2 Concepts of holographic data storage and content-addressable search

There are two versions of the holographic storage technology which are currently being pursued by different groups throughout the world, namely page-based and bit-based holographic storage. In page-based volume holographic storage, the information bearing object beam which is passed through an SLM or a data mask, interferes coherently with a reference beam inside a thick storage material forming a stationary interference pattern (Fig 1.1(a)). The recording material stores the interference pattern as a change in certain optical properties (such as absorption, refractive index and/or thickness) of the photosensitive medium. The remarkable attributes of

the page-oriented volume HDS are achieved by recording information throughout the volume of the recording medium and by transferring data in parallel rather than serially. By exploiting the Bragg selectivity, multiple such data pages can be superimposed in the same location of the recording medium by changing the properties such as spatial position, angle, wavelength, and phase etc. of the reference beam, which is referred to as multiplexing. When the multiplexed volume holographic memory is illuminated with the appropriately indexed reference beam, the corresponding object wave is reconstructed. A lens can be used to image the reconstructed object wave onto a detector array (CCD or CMOS) (Fig. 1.1(b)). This object wave is further processed to get back the original information and is also used to determine the system properties.

A unique feature of the page-based HDS systems is the associative retrieval or content-addressable search. In this technique, the multiplexed volume holographic memory is illuminated with the object beam which may contain a full or partial search data pattern (Fig. 1.2). This reconstructs simultaneously all the reference beams previously used to record multiplexed data pages. The amount of power diffracted into each reconstructed beam is proportional to the similarity between the input search data pattern and the recorded data pages. These reconstructed beams are focused onto a detector array to form the correlation peaks and the intensity at each correlation peak is used to determine the amount of similarity between the search data pattern and the recorded data pages. Since the search data pattern is simultaneously and optically compared with all the recorded pages (of a single location)


48

by using a single exposure, volume holographic systems can potentially perform parallel data search much

faster than the conventional sequential data search.

(a)

Referencebeam

Signalbeam

L1

SLM

Recording media

Fig. 1.1 (a) Recording of holographic data pages, (b) Reconstruction with appropriately indexed reference beam. L1, L2: lens and SLM: spatial light modulator.

(b)

Referencebeam

L2

Recording media

Detector array


49

This kind of parallelism is necessary for high-capacity correlation calculations, such as associative retrieval, pattern recognition, target tracking, and navigation. Over the years, researchers have demonstrated the parallel retrieval of up to 2030 correlation spots from a single location in a crystal.

Holographic optical disk systems are also used as a high speed search engine for image and video data. Several different recording architectures for the page-based HDS systems have been explored since HDS was proposed by van Heerden. These different suggested holographic storage concepts have been investigated in detail by many research groups and companies. Designs vary by holographic multiplexing methods, recording material characteristics, cost and size of available components, and the desire for compatibility with the

existing data storage formats. The book entitled “Holographic Data Storage” by Coufal et al. provides an introduction to the field of holographic data storage and includes important articles that describe the fundamental issues concerning HDS systems. It also describes the state of the technology and the most significant demonstration platforms at the end of the 1990s. A few other important review articles are “Holographic data storage” by Ashley et al., “Holography for information storage and processing” by Burr et al., and “Holographic data storage systems” by Hesselink et al.. These articles also discuss the fundamental issues underlying holographic data storage and provide new insights for the development of a holographic disk drive.

Currently there are significant interests in three different HDS architectures. The first architecture is the angle-polytopic, which utilizes the traditional two-beam angle

Fig. 1.2 Content-addressable searching with a partial search data

pattern. L3: lens.

SLM

L1 Signalbeam

Recording media

CorrelationDetector

L3


50

multiplexing to overlap many megapixel hologram in “books” at a single location, and then uses polytopic multiplexing to further overlap neighboring books to achieve high storage density. The second architecture is the collinear holography, which uses a single recording beam containing both the signal and the reference beam components. The holograms are recorded in a medium with a reflective substrate. Multiplexing is achieved by exploiting fine x, y shift selectivity to densely overlap the holograms. There are two competitive arrangements for the reflection type coaxial holographic storage systems: the optical layout developed by OPTWARE, which is a so-called collinear or “split-aperture system” and the “common-aperture system” developed by the European consortium named ATHOS (Advanced Technology for Holographic Storage). A comparison of these two coaxial arrangements has been performed by Kárpáti et al.. The third architecture is a concept based on the counter propagating beams to record reflective volume gratings for HDS. Multiplexing is again achieved by exploiting fine x, y shift selectivity. A comparison of the different HDS architectures with regard to their beam overlap, efficiency of material consumption, diffraction efficiency, and crosstalk characteristics has been done by Przygodda et al., and Ayres and McLeod. In contrast to the page-oriented holographic memories that generally rely on plane-wave hologram recording, in a bit-based holographic storage, which is also referred to as microholographic storage, data are recorded bit-wise as microscopic-sized reflection holograms. Strong localization of the grating like index modulation is achieved by using a

sharply focused diffraction limited laser beam for writing. When the write beam is overlapped with its retro-reflected or counter propagating part, a reflection grating is created in a microlocalized volume element comparable to the joint volume of the two beams. Microholographic storage promises a relatively straightforward compatibility with traditional optical disc formats due to similarities in their basic architecture, while the page-based approach requires the development of a completely new format. However compared to the page-based holographic storage, microholographic storage is still in the early stage of development.

In the year 2007, Inphase Technologies (USA), a Bell Labs spinoff, launched the first holographic disk drive (page-oriented) named TapestryTM300R. The device stores 300 GB on a single holographic disk at a transfer rate of 160 Mb/s. The recorded data pages are of 1.48 Mb size and each holographic disc contains 4.4 million such pages [www.inphase-technologies.com/downloads/pdf/products/2007TapestryProductBrochure.pdf]. Other companies such as STX Aprilis Inc., USA and Optware Japan are also developing their own holographic disk drive prototypes.

1.3 Research overview

Research activities during the past few years are mainly concentrated in the areas of developing suitable storage material for HDS with the especial attention to photopolymer recording materials, two-dimensional data encoding and efficient data retrieval techniques, system architectures and design tolerances, content-addressable data search and optical correlators. New and improved methods have been developed to optimize the performance


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of HDS systems in terms of storage density, data transfer rate, and data access time. In addition, issues related to product development and commercialization of HDS systems is also tackled. In the area of storage material, significant research work and advances have been reported on photopolymer based recording materials. The main interests being on polyvinyl alcohol (PVA)/ acrylamide polymers and poly (methyl methacrylate) (PMMA) materials. Besides these, recording material such as polymers based on sol-gel matrix, photorefractive polymers and photorefractive crystals and other recording materials have also been investigated. A better understanding of the grating formation through the development of new and improved models for hologram recording in the photopolymer materials grabbed much attention of the researchers. In the field of two-dimensional data encoding and retrieval techniques, sophisticated schemes such as employment of purely phase-modulated binary data pages, the implementation of amplitude-based gray-scale and sparse-gray-scale data pages, and the realization of hybrid ternary- and hybrid multinary modulation have been investigated. Methods for the detection of purely phase-modulated data pages and hybrid multinary modulation coded data pages were also introduced. Several new error correctible two-dimensional modulation codes, signal processing and data detection schemes for distortion, crosstalk, misalignment, tilt, interpixel interference compensation, and equalization techniques have also been proposed.

With regard to the addressing schemes in the reference beam arm, several new multiplexing approaches have been proposed such as shift multiplexing in thin media, speckle multiplexing based on random phase encoding and fibers, phase-code multiplexing, polytopic-angle multiplexing, collinear multiplexing methods, and other innovative multiplexing techniques. Noteworthy contributions were demonstrated in various holographic disk and holographic drive related issues such as design of tracking servo control system, design of track pattern, design and tolerances of high numerical aperture and high-resolution objective lenses, media tilt detection and tolerances and formatting for intelligence control. Several other important topics of HDS systems such as effects of aberrations and recording material shrinkage, thermal expansion of the recording media, erasure of holograms in photorefractive and photopolymer materials, optimization of geometrical size and shape of the aperture used in the hologram plane, parallel copying of holograms, development of simulation models of HDS systems, exposure scheduling and angular interval scheduling for multiplexed holographic memory, multilayered holographic storage, dual-channel holographic memory, encrypted holographic memories, and other miscellaneous issues were also investigated. Finally, significant advancements in the area of associative retrieval and volume holographic correlators were also reported. For content-addressable searching with angular multiplexing method, several new data encoding schemes are introduced in order to reduce the error probability. However for phase-code multiplexing method, techniques to overcome the


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shortcoming and to perform true associative data searches are proposed. Investigations were also performed to study the reliability of associative recall. In the direction of volume holographic correlators, sophisticated methods such as the use of Walsh transform, speckle modulation, wavelet transform, interleaving, gated localized holography etc. are developed to perform efficient and high speed optical correlations.

1.4 Motivation for the present work

Despite the vast research activities over the last four decades or so, it is believed that there is still enormous scope for improvement and enhancement of the performance of HDS systems both from the perspectives of storage density and associative recall. The initial HDS products/prototypes fall far short of the promised capabilities of the HDS technology. In order to realize the promised features we need to make better use of the inherent potential of volume holography. The Fourier transform (FT) configuration or the 4f architecture is the most widely used configuration for HDS systems. In this architecture, the recording material is placed near the back focal plane or the FT plane of the objective lens. Recording of data in a holographic storage device is conducted by converting an electronic input data stream into a two-dimensional data page. By use of an SLM, a facsimile of the data page is imprinted onto an incident collimated laser beam to form a signal wave. A data page for holographic storage typically uses binary encoding, in which pixels of the SLM encode two distinct states: ‘OFF’ and ‘ON’ corresponding to binary data bit ‘0’ and ‘1’, respectively. In the vast

majority of the research performed so far, the data pages were commonly displayed by pure amplitude modulations. The FT of an amplitude modulated data page gives rise to high intensity zero-order (dc) spot. Thus the recording material is illuminated very inhomogeneouly because of the presence of the strong dc spot which is not suitable for hologram recording. Such non-uniform intensity distribution in the hologram plane is undesirable and requires a large dynamic range from the recording material. If allowed to be present, these high intensity spots lead to non-uniform media usages and result in the saturation of the recording material during multiplexed recording. So it is necessary to uniformize the object beam distribution in the hologram plane. Serious efforts have been made in this direction over the past few years of research and as a result several methods have been put forward to avoid this undesirable effect of the dc spot in the case of amplitude modulated data pages. One such ingeniously simple method is to place the recording material away from the FT plane (defocused recording) that prevents the recording material from being illuminated by a focused dc spot. As mentioned earlier, data pages for holographic storage typically use binary encoding in which pixels of the SLM encode two distinct states ‘0’ and ‘1’. The maximum code rate that can be achieved with binary encoding is unity when the block size goes to infinity, which limits the data capacity of each page. However for many storage systems (even for CDs, DVDs, and BDs), the code rate is the best compromise between the storage capacity and error correction. The code rate is usually kept below 1.0, since larger block sizes suffer a sharp bit-error-rate (BER) performance loss due


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to the phenomenon of error propagation. Thus any further increase in the code rate can only be achieved by utilizing more channel states and hence non-binary modulation codes. The use of non-binary or gray-scale modulation codes for HDS systems has been investigated by several authors. Gray scale encoding increases the code rate beyond unity, thereby enhancing the capacity of each page and also improving the transfer speed. Although known, the use of gray-scale data pages for holographic storage has not been widespread. One possible reason may be the lack of suitable multilevel SLMs. Also these earlier studies on gray-scale encoding are based on amplitude-modulated SLMs producing a very sharp dc component at the FT plane which is not desirable. The inspiration of the proposed thesis on holographic digital data storage is derived from the above mentioned two different aspects of obtaining a homogenized Fourier spectrum in the hologram plane and the utilization of multi-level data pages for HDS systems. The two well-defined motivations can be categorized as - (1) To investigate and analyze the defocused volume holographic recording geometry both from the point of view of storage density as well as content-addressable searching. To perform a comparative study with the FT plane recording geometry in order to understand the possible merits and demerits of both the FT plane recording and away from the FT plane recording geometry. To efficiently exploit the knowledge accumulated from these studies for further improving the system performance by devising new methods. (2) To develop new methods for gray-scale data encoding for tweaking the

performance of HDS systems. The new methods should produce ‘homogenized Fourier spectrum’ which is necessary for recording highly efficient holograms in the FT plane (a serious bottleneck of the previously known methods of gray-scale data page encoding). Further to study the concepts and also to introduce new ideas for the sparse-gray-scale data page encoding for holographic memories, and to explore the read-out methods and other relevant parameters.

1.5 Objectives of the thesis

Even though considerable amount of research work has been performed over the past few decades in holographic data storage, only a few studies have been reported in the literature that fully investigate the defocused (away from the FT plane) volume holographic recording geometry. Also in vast majority of the holographic storage concepts, data pages are commonly represented by pure (binary or gray-level) amplitude modulations and only a few previous holographic systems employed the phase modulations in the signal arm. The objectives of the current thesis are the development, implementation, and investigation of novel approaches for enhancing the performance of HDS systems keeping in mind the above mentioned facts. The major objectives and goals of the thesis are • To investigate and evaluate the

defocused recording geometry of HDS systems. Numerical evaluation of the BER and the content-addressable search capability as a function of size of the aperture used in the hologram plane and as a function of position of the recording material away from the FT plane. Also to perform


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a comparison with the FT plane recording case.

• To develop a numerical simulation

model considering photopolymer recording materials in order to investigate the effects of recording material saturation on the BER of the reconstructed data pages, signal-to-noise ratio (SNR), and the content-addressable searching. To explore the effectiveness of defocusing the recording material away from the Fourier plane in overcoming this saturation effect for error free data recovery.

• To introduce and demonstrate new

methods for content-addressable data search in a defocused volume holographic content-addressable memory in order to remove the high cross-correlation peaks occurring in the previously known methods. Also to investigate the reliability of content-addressable searching in a defocused HDS system under realistic conditions.

• To construct new data channel

encoding scheme that utilizes pure phase modulations for gray-scale data page based HDS systems. Suitable phase modulations produce a homogenized Fourier spectrum and hence expected to increase the SNR of the recovered data pages.

• To experimentally demonstrate the

new data channel encoding scheme for three-gray-level data page HDS systems. The primary aim is to characterize and use a twisted-nematic liquid-crystal (TNLC) display as a pure phase-modulator for the gray-level data page holographic storage system.

• To design and employ new

methods for implementation of sparse-gray-scale block modulation codes with a single SLM in phase mode for HDS systems. To develop suitable read-out method for the recovery of data from the phase information.

1.6 Structure of the thesis and its

contents

The present thesis reports the results of the investigations on the defocused volume holographic recording geometry for HDS systems and on the application of phase-modulated data pixels for holographic storage with gray-level balanced and sparse-gray-scale modulation codes. We simulate the defocused volume holographic recording geometry both with and without considering the recording material properties. Subsequently, we introduce novel content-addressable data search concepts for the defocused volume HDS systems. Next, we introduce the concepts of phase-modulated data pixels in order to obtain a dc removed Fourier spectrum with gray-scale balanced and sparse-gray-scale modulation coded data pages. Chapter 1 contains introduction, motivation, and the basic concepts of the holographic data storage and the content-addressable holographic memory. It also includes an overview of the research activities during the past few years. At last it contains the objectives, the thesis contents and its structure. Chapter 2 explains the basic principles of content-addressable data search and BER characteristics of a defocused volume HDS system. The chapter also explains the drawbacks of the 4f recording geometry when the


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medium is placed at the FT plane of the objective lens for amplitude modulated data pages. A detailed account of the numerical simulation performed and the discussion of the results are presented. It shows the results of our investigations on the performance of a defocused HDS system in terms of BER and content-addressable search capability as a function of the size of the aperture in the Fourier plane and as a function of position of the recording material away from the FT plane. We have investigated the BER performance of the defocused HDS system for various

apertures placed in the hologram plane. The simulation results show that we should use an aperture of larger dimension to decrease the BER while going away from the Fourier plane (Fig. 3). Moreover, we have also studied the correlation properties of a defocused HDS system by varying the aperture size and defocusing distance. We have shown that while going away from the Fourier plane, the correlation capability of the HDS system for amplitude data pages does not vary significantly compared to that for the Fourier plane recording (Fig. 4).

Chapter 3 presents a numerical simulation technique to study the saturation effects of the photopolymer medium on holographic data storage and search. Saturation of the photopolymer material is taken into account by considering a non-linear behavior of the index modulation with exposure as proposed by Piazzolla and enkins [1996, 1999]. Both Fourier and

off-Fourier plane recordings have been simulated. We have calculated the local modulation of the dielectric constant that describes the recorded hologram, taking the parameters of the photopolymer recording material and the optical process into account. We further investigated the influence of this material saturation on the raw BER and SNR of the reconstructed data page, and the content-addressability. It has been found that the material saturation has serious effects on the

Fig. 3 Plot of BER as a function of aperture size (in the units of Nyquist aperture); dotted horizontal line shows the acceptable limit of the raw BER.

0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.210

-15

10-10

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100

0.0f0.1f0.2fraw BER limit

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R


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performance of the HDS system with high raw BER (0.43) and low SNR (0.16). Defocusing the recording material decreases this saturation and improves the raw BER (0.0) (Fig. 5) and the SNR (4.48) (Fig. 6). Thus although defocusing the material away from the Fourier plane results in the improvement of the raw BER value,

the correlation properties deteriorate with the cross-correlation peaks being higher in intensity. This simulation technique can be efficiently used for the improvement and optimization of the HDS systems that employ the photopolymer recording materials.

Fig. 4 Correlation peak height (arbitrary units) vs. the size of the search argument in percentage with the same page as the stored page (‘□’ for Fourier plane and ‘○’ for 0.25f away from Fourier pane) and with a different page (‘×’ for Fourier plane and ‘◊’ for 0.25f away from Fourier plane).

Size of the page in

Cor

rela

tion

peak

hei

ght (

a.u.

)

0 20 40 60 80 10010

3

104

105

106

107

108

0.0f0.25f0.0f0.25f

Fig. 5 Raw BER as a function of distance of the recording material away from the Fourier plane for an aperture of 1.4 DN in the hologram plane.

0 0.05 0.1 0.15 0.2 0.25 0.3 0.3510

-5

10-4

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Chapter 4 introduces a new dc-filtering based content-addressable searching method for defocused volume HDS systems with binary data pages. Content-addressable searching with defocused recording usually results in higher cross-correlation peak intensities. This new method allows to perform faithful content-addressable search both for binary balanced and sparse data pages. Both numerical and experimental results are presented. Subsequently, we explore the correlation behaviour of the dc-filtering based searching method when the recorded data sets possess different degrees of similarity. Experiment is also performed for another known method of searching namely phase-based searching method. It has been experimentally found that both phase-based and dc-filtering based searching methods can lead to highly ambiguous search outcomes. Two methods based on the block modulation codes used to encode user binary data into holographic data pages are investigated to remove the undesired correlation behaviour from the defocused volume holographic optical correlation processor. Chapter 5 reports the use of phase-modulated data pixels for HDS systems

with gray-scale data pages. The inherent drawback of the conventional amplitude based gray-level data pages is analyzed and simulation results showing the advantages of phase-modulated gray-scale data pages are described. Construction of phase-modulated gray-scale data pages and their recovery, Fourier plane light homogeneity, BER, storage density, phase modulation error of the SLM, and misalignment tolerances are investigated through computer simulation. An experimental demonstration of the newly developed gray-level phase data page method is also presented (Fig. 7). Experimental results of the phase and amplitude modulation characteristics of a TNLC SLM, Fourier plane light homogeneity, and the recording and reconstruction of phase-modulated binary, gray-scale data pages and their recovery with the real-time holographic interferometric (RTHI) method are presented. In Chapter 6, we propose a new method to realize the sparse-gray-scale modulation codes with a single phase-modulating SLM for HDS systems, producing a homogenized Fourier spectrum for efficient exploitation of the recording material’s dynamic range. Construction of three-gray-level sparse phase data pages with

0 0.05 0.1 0.15 0.2 0.25 0.30

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Defocusing z/f

SNR

Fig. 6 SNR as a function of distance of the recording material away from the Fourier plane for an aperture of 1.4 DN in the hologram plane.


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simultaneous balancing of the different phase states in order to remove the dc spot is discussed. The influence of the low-pass aperture size on BER and the read-out method is also discussed extensively. We also explore theoretically the potential storage density improvement while using low-pass filtering and sparse-gray-level phase data pages for holographic storage and demonstrate the trade-off between the code rate, the block length, and the estimated capacity gain (Fig. 8). Chapter 7 contains a summary of the research contributions made. Concluding remarks on the attained results and the scope of future work in the area of HDS systems and content-addressable search are provided. The

holographic simulation model with photopolymer recording material presented in Chapter 3 can be used as an efficient tool for system optimization. The new content-addressable searching method together with the modulation code subtleties described in Chapter 4 allows to perform reliable associative search in a holographic memory. Finally, the phase-modulation based gray-scale balanced and sparse-gray-scale data page methods for HDS systems presented in Chapters 5 and 6 have the potential to achieve a significant gain in the storage density. Finally, a list of references cited in the thesis, has been given.

(a) (b) (c)

Fig. 7 Experimental results for the three-gray-level phase-modulated data page; (a) Three gray level data page, (b) Four gray level version of (a) to be displayed as four level phase information, and (c) Retrieved three-gray-level data page using RTHI.

1 1.2 1.4 1.6 1.8 20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Aperture size related to Nyquist aperture

Normalized Storage Density

67% 50% 24% 12%

Sparsity

Fig. 8 Normalized storage density as a function of the low-


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The research work reported in the thesis has resulted in the following publications: 1. Bhargab Das, Joby Joseph, and

Kehar Singh, “Performance analysis of content-addressable search and bit-error rate characteristics of a defocused volume holographic data storage system,” Appl. Opt. 46, 5461-5470 (2007).

2. Bhargab Das, Joby Joseph, and Kehar Singh, “Material saturation in photopolymer holographic data recording and its effects on bit-error-rate and content-addressable search,” Opt. Commun. 282, 177-184 (2009).

3. Bhargab Das, Joby Joseph, and Kehar Singh, “Improved data search by zero-order (dc) peak filtering in a defocused volume holographic content-addressable memory,” Appl. Opt. 48, 55-63 (2009).

4. Bhargab Das, Joby Joseph, and Kehar Singh, “Phase modulated gray-scale data pages for digital holographic data storage,” Opt. Commun. 282, 2147-2154 (2009).

5. Bhargab Das, Sunil Vyas, Joby Joseph, P. Senthilkumaran, and Kehar Singh, “Transmission type twisted nematic liquid crystal display for three gray-level phase-modulated holographic data storage systems,” Opt. Lasers Eng. 47, 1150-1159 (2009).

6. Bhargab Das, Joby Joseph, and Kehar Singh, “Phase-image-based sparse-gray-level data pages for holographic data storage,” Appl. Opt. 48, 5240-5250 (2009).

7. Bhargab Das, Joby Joseph, and Kehar Singh, “Reliability of content-addressable data search in a defocused volume holographic data storage system,” Appl. Opt. 49, 781-789 (2010).

The Author is presently working as a postdoctoral fellow at University of Massachusetts, Boston. Email: [email protected]

Instrument of the Issue Small-angle X-ray scattering (SAXS)

Dr. Bipul Sarma

Introduction

Microscopy and X-ray diffraction are the most useful and powerful analytical techniques for the characterization of materials. Microscopy is good for local and surface details of an object however X-ray is good for global parameter distribution, sample states and transitions. X-ray, neutron, or electron is used in powder diffraction for structural characterization of powder or microcrystalline materials.

Crystalline material offers much stronger signal due to the periodicity of molecules in the lattice and they have Fourier transform which can be plotted or observed as peaks over noise. However for a liquid or powder or amorphous sample, molecules within that sample are in random orientations. They have a continuous Fourier spectrum that uniformly spreads its amplitude thereby reducing the measured signal intensity.



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This can be observed in Small Angle X-ray Scattering (SAXS). SAXS is a powerful and nondestructive method for analyzing nanostructure materials. Depending on the energy of the incident particle (electron, neutron) scattering could be of two types in particle technology, (a) inelastic and (b) elastic scattering. In inelastic scattering process, the energy of the incident particle is not conserved however conservation of energy before and after collision is elastic scattering. The inelastic scattering process is called Raman scattering when a photon is the incident particle. Small-angle elastic X-ray of wavelength 0.1 to 0.2 nm is used in SAXS. The angle ranges typically from 0.1 to 10° that carries information about the shape and size of macromolecules, characteristic distances of partially ordered materials, pore sizes, and relevant data for detail characterization of materials. This small angle X-ray is powerful techniques for structural information of macromolecules between 5 to 25 nm, and partially up to 150 nm. The advantages of SAXS are the capability of delivering structural information for non crystalline materials which is not possible for biological macromolecules and proteins. But due to random orientation of dissolved molecules may

leads to a loss of information in SAXS compared to crystallography. Applications range from life science and biotechnology for proteins, viruses and DNA complexes to polymers, emulsions, liquid crystals, fibers and catalysts. Principles

When X-rays pass through a sample they scatter. X-rays are waves (typical wavelength λ=1.54 Å) so they diffract and interfere like light, sound or seismic waves. Some samples are periodic e.g. atoms in a crystal, other samples consist of a random arrangement of objects such as molecules in solution, fat globules in milk or water droplets in a cloud. But the general relationship between scattering angle and size of the object is,

For example, a protein approximately 25 Å size will scatter X-rays out to about 2 degrees. If eight protein molecules clump together to make a molecule of rough size 50 Å, the X-ray scattering will now contract inside a disk of size 1 degree. Intense scattering over a range of angles means the structure is ordered on that length scale but is not be periodic.

http://en.wikipedia.org/wiki/Macromolecule


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Bragg's Law [nλ=2dsinθ], generally supports measurement of half as minimum size but does not quantify the maximum size limit in a diffraction experiment. This Law also assures that nano to colloidal size structures would carry valuable information below 6° (2θ) in diffraction pattern and SAXS is specially designed instruments to measure down to less than 1/1000 of a degree. This measurement is up to 1-micron scale structures using x-rays. In x-ray diffraction, scattered intensity depends on the Lorentz-Polarization factor (equal to 1 below 6° 2θ) and the structure factor, |F2|. The atomic scattering factor is equal to the square of the number of electrons in an atom at low angles {ne

2(1/q)}, where q is 4π sin(θ)/λ. Also the intensity of scattering is known to be proportional to the number of scattering elements in the irradiated volume {Np(1/q)}. Now for small-angle scattering, a generalized rule of thumb that describes the behavior of scattered intensity as a function of Bragg size "d" or "r" that is observed at a given scattering angle 2θ, where r = 1/q is I(q) = Np(1/q) ne

2(1/q) This equation is known as power law and reflects the scattered intensity is proportional to the decay of the particle volume with size and the size (r), of a scattering element is a component of a physical domain. Porod's Law: For a smooth surface particle like sphere, the surface can be decomposed into spherical scattering elements. The number of such spheres is proportional to the surface area for the particles divided by the area per scattering element, r2 or 1/q2, while the number of electrons per particle is just proportional to r3 or 1/q3. From the rule of thumb with Np = Sq2 and ne = 1/q3, yields I(q) = S/q4. This is Porod's Law for surface scattering to measure the

surface area of domains in the nano-scale. The following equation can be derived from this law introducing electron density (ρ) difference between particle and matrix domain.

I(q) = Ie 2p r2 S/q4 Ie is a constant, S is surface area There are other general categories of power-laws that are well defined in small-angle scattering are, (a) Surface-Fractal Laws (systems do not have smooth surfaces) (b) Diffuse interface Laws (when a concentration gradient is observed at an interface in mixing of two liquids or dissolution of a particle) (c) Mass-Fractal or Dimensional Laws (When particles are described in terms of their dimensions like a rod is 1-D, a disk 2-D and a sphere 3-D and for a mass-fractal object such as a polymer coil the mass is given by the size raised to the dimension). (d) Polydispersity of particle size (systems display dispersion in particle size) Guinier's Law: Power-law decays in scattering do not consider a particle in the sense by allowing the particle structure to be averaged with respect to position and rotation for an isotropic system. For the determination of moment of inertia of an isotropic system one must consider, (i) average all possible positions in the particle from which a vector "r" can start and be within the particle, (ii) determine the probability that a randomly directed vector "r" from an arbitrary starting point in the particle will fall in the particle. This moment of inertia is called the radius of gyration (Rg) of the particle because electron density is


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used as the weighting rather than the mass density. For a system of disperse shaped and sized particles the radius of gyration reflects a second moment of the distribution of the shape and size about the mean. The meaning of this probability p(r), in the vicinity of r = the particle size, can be graphically represented by a Gaussian probability cloud created by the summation of all possible positions of the particle where the center of the probability cloud is in the particle phase. The average size is now reflected in the radius of gyration and known as Guiner’s law.

I(q) = Np ne2 exp(-q2Rg

2/3)

Depending on the radius of gyration of different shape and size particle like sphere, rod, disc, polymer coil etc we can derive special scattering functions for I(q) from Guiner’s law.

The instrument

Small angle x-ray scattering instrument can be two types,

(a) Point-collimation instruments: This instrument is made in such a way that the x-ray beam scattering is centro-symmetrically distributed and the scattering patterns consist of circles around the primary beam. The scattered intensity is low and therefore the measurement time is in the order of hours or days in case of very weak scatterers. Using focusing optics (bent mirrors, bent monochromator crystals) or collimating and monochromating optics measurement time can be reduced. Non-isotropic systems like fibres, sheared liquids can be determined using Point-collimation.

(b) Line-collimation instruments: The beam profile is a long and narrow line. The disadvantage of this instrument is the illuminated sample volume which is much larger compared to point-collimation and the scattered intensity at the same flux density is proportionally larger. However measurement time is much shorter compared to point-collimation. This instrument can be used only if the system is isotropic. Use of Line collimation is rare in small-angle X-ray scattering due to the increasing number of synchrotron sources which are all point sources, and due to the availability of more powerful X-ray laboratory sources in combination with new multilayer optics.

http://en.wikipedia.org/wiki/Monochromator

http://en.wikipedia.org/wiki/Fibre

http://en.wikipedia.org/wiki/Shearing_%28physics%29


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WAXS SAXS

Detector close to sample. Distortion of reciprocal space mapping. Thermal effects when heating sample. No ion chamber for absorption

Detector far from sample. Absorption from intermediate space. Interception of appropriate q range

Applications: For the determination of microscale and nanoscale structure, small angle x-ray scattering (SAXS) is the most powerful and used instrument in current research. The principle of this instrument is based on averaging particle sizes, shapes, distribution, and surface-to-volume ratio. This is independent of the phase of the materials. It can either solid, liquid or can be gaseous particles. Any combinations of them are allowed. Applications are very broad and include colloids of all types, metals, cement, oil, polymers, plastics, proteins, foods and pharmaceuticals.

This instrument is found in research as quality control. Apart from micro- or nano- structures it is possible to analyze lamellae, and fractal-like materials. The method is accurate, non-destructive and usually requires only a minimum of sample preparation.

The differences in basic experimental consequences with wide angle x-ray scattering (WAXS) are tabulated below. References J. Appl. Crystallogr. 1995, 28, 717-28. J. Appl. Crystallogr. 1996, 29, 134-146. J. Chem. Phys. 2006, 125, 234904-08. www.wikipedia.org

Letter from Members

Akashi Baruah

Since the day of its birth North-East India Research Group has been a great source of help as well as inspiration for all the people involved with. I feel proud being a member of this family. I have been greatly benefited by the research articles sent by various members throughout my PhD period, as most of the journals are not accessible in our department. The selfless help of these people is really admirable. Besides sharing of different thoughts, ideas, experiences and above all the important links help a lot. I have submitted my thesis and looking for a post-doc and North-East Research group is helping me a lot. Thanks to all the people in this forum and long-live North-East Research Group

http://en.wikipedia.org/wiki/Colloid

http://en.wikipedia.org/wiki/Polymer

http://en.wikipedia.org/wiki/Proteins

http://en.wikipedia.org/wiki/Pharmaceutical

http://en.wikipedia.org/wiki/Lamella_%28materials%29

http://en.wikipedia.org/wiki/Fractal


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Members Face

Progyashree Goswami, daughter of Guna Kanta Goswami from Dakhin Sarbaibondha, Jorhat district, received

her education in Jorhat and then completed her Master’s of Science from Dibrugarh University in 2007. After the completion of her M.Sc. (Organic Chemistry) she joined as research fellow at Tea Research Association, Tocklai, Jorhat for only a few months and then she moved to the Natural Products Chemistry Division, North East Institute of Science and Technology (NEIST, formerly RRL), Jorhat, Assam in 2008 December to pursue her Ph.D. degree under the supervision of Dr. J C Sarma (scientist-F). She is being registered as Ph.D. Student under Gauhati University, Guwahati.

Kalyan Jyoti Borah is working as senior research fellow (CSIR) in the Department of Chemical Sciences, Tezpur University, Napaam, Assam. He is carrying out his research work towards the Ph. D degree in the field of synthetic organic chemistry under the supervision of Dr. Ruli Borah, Associate Professor. His areas of research interest are mainly green

chemistry and heterocyclic chemistry. He has published his works in six reputed international journals. Before joining Ph. D programme in Tezpur University he worked as a project assistant in the Medicinal Chemistry Division, NEIST, Jorhat for two years. He is son of Mr Daya Ram Borah and Mrs Mamoni Borah of Adarsha Nagar Milanpur, Nagaon, Assam. He did schooling from Manaha High School of Morigaon district, Assam and then completed graduation from Jagiroad College under Gauhati University and M. Sc from Gauhati University in Organic Chemistry in the year of 2002. His future plan is to absorb in a research oriented job. E-mail: [email protected]

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Job, Post doc Etc. (1) Process Development specialist: Dr Reddy’s Laboratories Ltd. Hyderabad, India ( Apply in the company site) Roles & Responsibilities:

• Provide leadership for process development and scale-up of novel or known forms • Study the stability and kinetics of transformation of meta-stable forms in solution, during drying, and in storage.

• Identify the critical parameters to consistently obtain the desired form • Implement Design Of Experiment for optimization and what-if studies • Identify scale-up criticalities, provide engineering calculations, and decide on suitable equipment for scale-up • Responsible for scale-up and validation of the process and along with Technical Support engineer • Recommend appropriate storage conditions and packaging • Interact closely with Product Development Teams to provide technical guidance where required • Complete characterization of Active Pharmaceutical Ingredients powder properties even if there is no specific requirement other than the polymorph

Essential Qualification & Experience:

• Chemical engineer (BTech / MTech / PhD) with 4 or more years experience in process development and scale-up • Expertise in crystallization and amorphous form generation • Knowledgeable on polymorph and powder property characterization • Ability to interact with cross-functional teams, such as PDTs and manufacturing • Good communication and interpersonal skills.

(2) Postdoctoral Position in Physics, Chemistry & Nanotechnology Sungkyunkwan University, Dept. of MSE, National Core Research Center, South Korea, Field(s): applied physics, chemical physics, material physics, nanotechnology Application deadline: Nov 08 (Mon), 2010 Submitted: Sep 08, 2010 Contact: Sang-Woo Kim E-mail: [email protected] Phone: +82-31-290-7352 Fax: +82-31-290-7381 Address: School of Advanced Materials Science and Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Center for Human Interface


Newsletter of North East India Research Forum

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Nanotechnology (HINT) (National Core Research Center), Sungkyunkwan University, Suwon 440-746, Republic of Korea Job description: NESEL (Nano Electronic Science and Engineering Laboratory) and HINT (Center for Human Interface Nanotechnology, National Core Research Center) at Sungkyunkwan University (Suwon, South Korea) is seeking a postdoctoral researcher in the following fields: - Synthesis or simulation of graphene - Study on graphene-metal electrode junctions (ohmic and Schottky contact) - Fabrication and characterization of functional devices based on grapheme The initial appointment will be one or two years and can be extended depending on the performance. This position will be started on January 1, 2011, but the starting date can be flexible. The annual salary ranges from 30 million KRW to 36 million KRW (As of Sept., 25,640 ~ 31,000 USD), depending on experience and qualification. This amount is enough for a family to make a comfortable living in South Korea. Applicants should send a CV including a publication list, a summary of research plan, and a reference list by email to [email protected] (Professor Sang-Woo Kim). Review of applications will continue until the position is filled. For any questions, please feel free to contact Professor Sang-Woo Kim. Professor Sang-Woo Kim School of Advanced Materials Science and Engineering Sungkyunkwan Advanced Institute of Nanotechnology (SAINT) Sungkyunkwan University, Suwon, South Korea Email: [email protected]

(3) Research positions in nanoscale characterization of optoelectrnic materials

At Center for Advanced Photovoltaics, SD State University, USA, Nano Labs Field(s): applied physics, chemical physics, chemistry, computational physics, condensed matter, material physics, measurement science technology, microscopy, nanotechnology, optics and optoelectronics, polymer physics, semiconductors, solid state physics, surface physics Application deadline: Nov 05 (Fri), 2010 Submitted: Sep 05, 2010 Contact: Venkat Bommisetty E-mail: [email protected] Fax: 605 688 4401 Job description: Nano Labs has multiple openings at research scientist/postdoc level in following areas.




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1. Nanocrystalline silicon (material and charge transport) 2. Organic solar cells 3. Scanning probe microscopy based electrical characterization and Scanning near-field optical microscopy 4. Dye-sensitized solar cells (nanoscale transport/interfaces) These positions are available immediately for one year appointment with possible renewal. Successful applicants will be responsible to lead a laboratory and have opportunities to co-supervise graduate student research. Interested candidates may send their resume and cover letter explaining how you qualify for a specific position and include 3 references. Successful candidates should have excellent publication track record and communications skills. (4) TATA INNOVATION FELLOWSHIP-2010, Department of Biotechnology, Ministry of Science & Technology Government of India

Applications are invited for "Tata innovation Fellowship", a highly competitive scheme of the Department of Biotechnology (DBT), Ministry of Science & Technology, Government of India. Objective: 1. The scheme is aimed at rewarding interdisciplinary work where major emphasis is on innovation and translational research with a potential towards commercialization.

Eligibility The fellowship is open to Indian Nationals residing in India who are below the age of 60 years

The applicant should possess a Ph.D degree in Life Sciences, Agriculture, Veterinary Sciences or a Master's degree in Medical Sciences, Engineering; or an equivalent degree in Biotechnology/related areas. The applicant must have adequate professional experience in the specific area and demonstrated leadership towards innovation The candidate must have a regular position in a University/ Organization /Institute/ and should be engaged in research and development. If he/she is availing any other fellowship (national/international), he/she will have to opt for only one of the fellowships (for example JC Bose fellowship Welcome Trust, Bill & Melinda Gates Foundation, NIH Senior fellowship Howard Hughes Medical Institute fellowship and others of similar nature)


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About the fellowship

The amount of the fellowship will be Rs.20,000/- per month in addition to regular salary from the host institute.

In addition, each fellow will receive a contingency grant of Rs. 5,00,000/- per annum for meeting the expenses on consumables, minor equipment, international and domestic travel, manpower and other contingent expenditure to be incurred in connection with the implementation of research project under the fellowship. Host Institution

The Institution where the candidate is working would provide the necessary infrastructure and administrative support for pursuing the research under this fellowship. The candidate will continue to work at the place of his/her employment. Duration

The duration of the fellowship will be initially for three years, extendable further by two years on a fresh appraisal. How to apply

Application (one copy) may be sent as per proforma downloadable from DBT website (www.dbtindia.nic.in) and duly forwarded by the competent authority to Dr. Meenakshi Munshi, Joint Director, Department of Biotechnology, Biock-2, T Floor, CGO Complex, Lodhi Road, New Delhi -110 003, Email :- [email protected] latest by 3Oth September, 2010. Other details regarding the fellowship may be seen at www.dbtindia.nic.in / www.dbtindia.gov.in.

More details please visit : www.dbtindia.gov.in

Click for the details in www.dbtindia.nic.in

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Science information through the lens

Photographs of hot basins in Yellowstone National Park, USA; the oldest national park in the world. ( Photos by Babita Baruwati)

http://www.dbtindia.gov.in/

http://www.dbtindia.gov.in/

http://www.dbtindia.nic.in/


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Details about the Northeast India Research Forum

Date of creation of the forum : 13th November 2004

Area: Science and Technology Total number of members till date: 350

Moderators 1. Arindam Adhikari, Ph.D. CECRI, Kadaikudi, Tamilnadu Email: [email protected]

2. Ashim J. Thakur, Ph.D. Tezpur University, Tezpur, Assam Email: [email protected]

3. Utpal Borah, Ph.D. Dibrugarh University, Assam, India Email: [email protected]

4. Khirud Gogoi, Ph.D. University of California, San Diego, La Jolla, USA; Email:[email protected]

Editorial Team of N.E. Quest

1. Debananda Ningthoujam, Ph.D. HOD, Biochemistry Dept. Manipur University, Imphal, India

2. Tankeswar Nath, Ph.D. Tezpur University, India

Email: [email protected]

3. Manab Sharma, Ph.D. Australia, Email: [email protected]

4. Shanta Laishram, Ph. D. Indian Statistical Institute, Delhi [email protected]

5 Pranjal Saikia, Ph.D. Gauhati University, Guwahati Email: [email protected]

6. Pankaj Bharali, PhD National Institute of Advanced Industrial Science & Technology, Japan Email: [email protected]

7. Sasanka Deka, Ph.D. Delhi University, Delhi Email: [email protected] 8. Robert Singh Thangjam, PhD Mizoram University, Aizwal, India Cover Page designed by: Anirban, Pune Logo designed by : Manab Sharma

9. Áshim Thakur, Ph.D. 10. Utpal Borah, Ph.D. 11. Arindam Adhikari, Ph.D. 12. Khirud Gogoi, Ph.D. 13. Babita Baruwati, Ph.D.

http://tech.groups.yahoo.com/group/northeast_india_research/ http://www.neindiaresearch.org/










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N.E.quest Vol 4 Issue 2 July 2010

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