S.N.Bose National Center for Basic

Sciences

Annual Science Day Celebration - Bose Fest 2020

ABSTRACTS OF POSTER CONTRIBUTIONS

P1.01. Decay of gravitational quantum state due tospin-velocity dependent interaction

Riddhi Chatterjee and Archan S. Majumdar

We study effect of single spin and velocity dependent MWDM potential on gravitationalquantum state created by bouncing fermion on a mirror under gravity. We calculate the ef-fective potential created by constituent neucleons of an infinite plane mirror. We show thatwavefunction of the bouncing fermion will decay as its motion is quantised. We calculate thedecay probability. We discuss the significance an possibility for experimental verification.

P1.02. Morphology and Ionization Characteristics ofPlanetary Nebulae PB 1 and PC 19

Rahul Bandyopadhyay, Ramkrishna Das and Soumen Mondal

In this work, we present results of our study of two planetary nebulae (PNe), PB1 andPC 19. The study has been done using the optical spectra of these PNe observed at 2 mHimalayan Chandra Telescope (HCT) along with archival and literature data. We use themorpho-kinematic code SHAPE for 3D morphological modeling and the photoionization codeCLOUDY for photoionization modeling of the PNe. The 3D model of PB 1 consists of an elon-gated shell surrounded by a bipolar halo and that of PC 19 consists of an open lobed bipolarstructure and a spiral filamentary pair. We study the ionization structure of the PNe by plasmaanalysis and photoionization modeling. We estimate the elemental abundances of the the el-ements, He, C, N, O, Ne, S, Ar, Cl, from our analysis, and also estimate different physicalparameters of the central stars, viz. effective temperature, luminosity and gravity, and of thenebula, viz. hydrogen density profiles, radii etc from photoionization modeling. We estimatedistances to PB 1 as 3.5 kpc and to PC 19 as 5 kpc by fitting the photoionization models toabsolute observed fluxes. We estimate progenitor masses, from theoretical evolutionary tra-jectories, as ∼1.54 solar masses and ∼1.96 solar masses for PB 1 and PC 19, respectively.

P1.03. Census of young stellar population in the Galactic H IIregion Sh2-242

Alik Panja, Soumen Mondal, Somnath Dutta1, Santosh Joshi2, Sneh Lata2 and RamkrishnaDas

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We present here identification and characterization of the young stellar population asso-ciated with an active star-forming site Sh2-242. We used our own new optical imaging andspectroscopic observa-tional data, including several archival catalogs, e.g., Pan-STARRS 1,Gaia DR2, IPHAS, WIRCam, 2MASS, and Spitzer. Slit spectroscopic results manifest the clas-sification of the main ionizing source BD+26 980 as an early-type star of spectral nature B0.5V. The spectrophotometric distance of the star is estimated as 2.08 ± 0.24 kpc, which confirmsthe source as a member of the cluster. An ex- tinction map, covering a large area (diameter ∼500) is generated with H and K photometry towards the region. From the map, three distinctlocations of peak extinction complexes (AV ’ 7-17 mag) are identified for the very first time.Using the infrared colour excess, a total of 33 Class I and 137 Class II young objects are clas-sified within the region. The IPHAS photometry reveals classification of 36 H emitting sources,which might be class II objects. Among 36 H emitting sources, 5 are already identified usinginfrared excess emission. All total 201 young objects are classified towards S242 from thisstudy. The membership status of the young sources are further windowed with the inclusion ofparallax from Gaia DR2 catalog. Using the optical and infrared colour magnitude diagrams,the YSOs are characterized with an average age of ∼ 1 Myr and the masses in the range 0.1 to3.0 M.The census of stellar content within the region are discussed using combined photometricand spectroscopic data.

1Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan.2Aryabhatta Research Institute of Observational Sciences, Nainital 263002, India.

P1.04. Interaction of gravitational and electromagneticradiation reaction for charged particles orbiting charged

black holesArnab Sarkar, Amna Ali1 and Archan S. Majumdar

We consider the equation of motion of a charged particle or a compact object in the spacetime of a charged black hole, under the reactions of electromagnetic radiation and gravita-tional radiation. We find the perturbation terms in this equation of motion, upto linear order,due to the interaction of the electromagnetic and gravitational wave radiation-reactions. Wediscuss the significance of these perturbation terms in the motion of the charged particle arounda black hole, specially in cases of charged non-rotating primordial black holes formed in theearly Universe. We shall try to discuss the importance of these systems for studying the earlyUniverse of the corresponding time.

1Department of Mathematics, University of Jadavpur, Kolkta -700032.

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P1.05. Anharmonicity can enhance the performance ofquantum refrigerators

Sourav Karar1, Shounak Datta, Sibasish Ghosh2 and Archan S. Majumdar

We explore a thermodynamical effect of anharmonicity present in quantum mechanical os-cillators. We show in the context of energy eigen spectrum that, quartic perturbations to thequantum harmonic oscillator potential, correct upto small values of the perturbation parame-ter, lead to the enhancement of performance of quantum refrigerators. A similar nonlinearitydriven enhancement of performance is also observed for an analogous spin-qubit model. Ourresults are illustrated for both the Otto and Stirling quantum refrigeration cycles. Finally, weinvestigate the energy cost for creating anharmonicity. The robustness of improvement of thecoefficient of performance versus the energy cost may be demonstrated for the experimentallyrealizable Otto refrigerator.

1Department of Physics, Government General Degree College, Muragachha, Nadia 741154, India.2Optics and Quantum Information Group, The Institute of Mathematical Sciences, HBNI, C. I. T. Campus, Tara-mani, Chennai 600113, India.

P2.01. Blackhole Phase TransitionNeeraj kumar and Sunandan Gangopadhyay

We have investigated phase transitions in arbitrary spacetime dimensions for Born-InfeldAdS black holes. The phase transition points are characterised from the divergence of heatcapacity of the black hole. Two well established techniques, namely, the Ehrenfest scheme andthe Ruppeiner state space geometry approach are used to identify the order of phase transitionthe black hole undergoes. It is observed that the results obtained from these two methods agreewith each other. Our analysis reveals that the phase transition is of second order. It is alsoobserved from the variation of the heat capacity with entropy that the small unstable black holephase becomes more and more stable with increase in the spacetime dimensions. We speculatethat this dependence of the stability of the black hole on the spacetime dimension can put anupper limit to the dimension of spacetime from the physical condition of the improbability ofthe formation of a small stable black hole.

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P2.02. Optimality in the noise due to receptor clustering forchemotactic performance of E.coli.

Shobhan Dev Mandal and Sakuntala Chatterjee

Noise in chemotactic signalling pathway has a very significant effect in run-and- tumblemotion of Escherichia coli (E. coli). The ability of the cell to perform good chemotaxis in inho-mogeneous concentration gradient largely depend on the noise originated from variable geneexpression and interaction between proteins in signalling network. Here we study the effect ofthe noise due to receptor clus- tering on E.coli chemotaxis. Our model of reaction network in-cludes the time evolution of three stochastic variables, receptor kinase activity, mehylation leveland Che Y-P protein level in flagellar motor. Che Y-P level dynamics is coupled to the kinaseactivity via time evolution equation and in case of methylation dy- namics we have consideredactivity-dependent modification of the methylation cites by the transmembrane chemoreceptorprotein Che R and Che B-P. For a good chemotactic performance in spatially varying nutri-ent profile the chemo- tactic bacteria must be able to climb up the increasing concentrationgradient quickly and localize in the high nutrient rich region in long time limit. Through oursimulation we have got a optimum value of cluster size at which chemotactic performance(Driftvelocity and localisation) is maximum and beyond that value performance worsens. This resultis striking since it is expected that at very large noise chemotaxis is weaker but here very smallnoise is also proved to be detrimental.

P2.03. Non-linear effects on the holographic superconductorsDebabrata Ghorai, Sunandan Gangopadhyay and Biswajit Chakraborty

We have analytically investigated some basic properties of holographic superconductorsin the presence of Einstein and Gauss-Bonnet gravity using three analytical method, namely,Sturm-Liouville eigenvalue method, matching method and thermodynamic geometry approach.The non-linear effect is introduced by considering the coupling of the massive charged scalarfield with Born-Infeld electrodynamics. We then calculate the relation between critical tem-perature and charge density from the divergence of the scalar curvature which is obtained byinvestigating the thermodynamic geometry of the model. The results indicate a decrease in thecritical temperature with increase in the Born-Infeld parameter b. We also investigate the non-linear effects on holographic free energy and conductivity of our holographic superconductorsmodels.

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P2.04. Rotating Holographic SuperconductorsAnkur Srivastav and Sunandan Gangopadhyay

We have investigated the role of black hole rotation in the holographic superconductors.Working in the probe limit, where the effect of matter fields into the background geometry canbe neglected, we have obtained the critical temperature and the value of the condensationoperator. It has been found that there is a critical value of the rotation parameter above whichthis model favours superconductivity.

P2.05. Hydrodynamics, giant fluctuations and condensationin self-propelled particles

Tanmoy Chakraborty, Subhadip Chakraborti1, Arghya Das1 and Punyabrata Pradhan

We derive hydrodynamics of a one dimensional model of self-propelled particles, havinglong-ranged hopping, which is motivated by Bacteria’s run-and-tumble dynamics. In the limitof infinite-ranged hopping, the model exhibits, upon tuning density and activity q , a conden-sation transition from a homogeneous fluid phase to an inhomogeneous “ordered” phase ofcoexisting fluid and a “condensate”. We analytically calculate two density dependent trans-port coefficients - the bulk-diffusion coefficient D(ρ) and the conductivity χ(ρ), the ratio ofwhich, despite violation of detailed balance, is connected to number fluctuation by an Einsteinrelation. Interestingly, at criticality and in the ordered phase, the bulk behaves like a “super-fluid” with diverging conductivity χ(ρ) ∼ (ρ −ρc)

−1 (or, equivalently, vanishing resistivity),implying “giant” number fluctuations (GNF) in the system.

1International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bengaluru 560089, In-dia.

P2.06. Study of transport in a system of particles withshort-range interaction and driven by a periodically moving

potentialDeepsikha Das, Sakuntala Chatterjee and Punyabrata Pradhan

The effect of time periodic potential on a many-particle system has been of considerableinterest in context of externally stirred fluids, such as in microfluidic devices or in an assembly

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of nano-particles driven by a periodically moving external potential. For example colloids in amoving optical trap have been investigated both theoretically and experimentally to understandtheir non-equilibrium time periodic steady states where macroscopic properties are periodicfunctions of time. The study becomes more interesting when inter-particle interactions are con-sidered. In the present study a system of one dimensional periodic lattice has been consideredwhere there is short range Ising interaction present between nearest neighbors.The interactionstrength denoted by the parameter (ε) has been varied from extreme attractive case (ε = −1)to extreme repulsive case (ε = 1) in steps to see the effect of its variation on particle currentgenerated in the system.Here it’s important to mention that ε = 0 and ε = 1 correspond to par-ticles with hardcore exclusion and with nearest neighbor exclusion respectively. Both the caseshave been studied in depth previously. It has been observed that for zero bulk hopping rate andat low to moderate particle densities, nearest neighbor exclusion facilitates maximum negativecurrent for the system. As the density increases beyond the half-filled case,some intermediaterepulsive strength overtakes and contribute for the maximum negative current.It is worthy tomention that for any ε value the maximum negative current is obtained at density much higherthan the half filled case. The nature of these behaviors has been understood qualitatively withthe help of simulation.The study for non zero bulk hopping rate is presently undergoing.

P2.07. 3d N = 2 ADE Chern-Simons Quiver Gauge Theories.Dharmesh Jain and Sunandan Gangopadhyay

We study 3d N = 2 supersymmetric Chern-Simons (CS) quiver gauge theories on a man-ifold with product geometry of 2d Riemann surface times a circle. Using localization results,we examine their partition functions in the large rank limit and requiring the resulting matrixmodels to be local, find a large class of quiver theories that include quivers in one-to-one cor-respondence with the ADE Dynkin diagrams. We compute explicitly the partition function forAD quivers, which lead to certain predictions for their holographic duals.

P3.01. Topological insulators in the 1T’ phase of MX2 (M=Mo, W; X= S, Se, Te) revisited

Prasun Boyal, Poonam Kumari and Priya Mahadevan

Mo and W based transition metal dichalcogenides (TMD) in the 1T’ phase are known tobe topological insulators [1]. This has been understood within the Kane-Mele model and isassociated with the level inversion between the anion p states and the transition metal d states.

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However, what is surprising is that this happens across the entire series varying the anionfrom S to Se to Te for both Mo and W based systems. Examining various families of topologicalinsulators, one finds that while one member of the series would be close to the point of inversion,it is not expected for every member to be close to the point of inversion and therefore becomea topological insulator. In this work, we study 1H , 1T and 1T’ phase of TMD extensively.We carry out ab-initio electronic structure calculations for each member of the TMD family.To quantify the electronic structure, we map the ab-initio band structure onto a tight bindingmodel. We show that above mentioned level inversion is not specific to 1T’ and also presentin 1H phase. Further we identify the relevant interactions that make all the Mo and W basedTMD to be topological insulator.

References:(1) X. Qian, J. Liu, L. Feu and J. Li, Science 346, 1344 (2016).

P3.02. Direct Observation of Unusual InterfacialDzyaloshinskii-Moriya Interaction in Graphene/NiFe/Ta

Heterostructure.Avinash Kumar Chaurasiya, Akash Kumar1, Rahul Gupta1, Sujeet Chaudhary1, Pranaba

Kishor Muduli1 and Anjan Barman

ne of the key motivations of modern spintronics research is to achieve low power con-sumption, faster information processing and higher storage density. To this end, graphene andother 2-D materials have shown promises. The interfacial Dzyaloshinskii Moriya interaction(iDMI) has drawn burgeoning interest due to its fundamental role in stabilizing chiral spintextures in ultrathin ferromagnets [1-2]. Recently, Yang et al. have reported the observationof significant DMI at the graphene-FM interface originating from Rashba effect [3]. Here,we demonstrate the first direct observation of iDMI in graphene/Ni80Fe20/Ta heterostructuresusing Brillouin light scattering (BLS) technique. We have used high-quality commercial CVDgraphene (from Graphenea) on a Si/SiO2 substrate. A series of samples consisting of sub-strate/graphene/Ni80Fe20 (t)/Ta (2), with t = 3, 4, 6, 8, 10, 15 nm were deposited at roomtemperature using DC magnetron sputtering at varying Ar working pressure and 3 Torr basepressure. The Ar working pressure for deposition of NiFe thin films on graphene was variedfrom 2 mTorr to 10 mTorr for inducing controlled defects in the graphene layer. By measuringfrequency non-reciprocity of Damon-Eshbach spin waves using BLS, we observed that iDMIconstant D scales linearly with the inverse of NiFe thickness revealing its purely interfacial ori-gin. Furthermore, by controlling the defects at the interface by Ar deposition pressure duringgrowth of Ni80Fe20, we established that the DMI in this system arises from the defect inducedextrinsic spin-orbit coupling. This is further supported by a correlation between the DMI andspin-mixing conductance (obtained from ferromagnetic resonance (FMR) measurement), bothof which are related to spin-orbit coupling [4]. Our detailed FM layer thickness and Ar pres-sure dependent study of iDMI will enrich the understanding of the observation and tunability of

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iDMI in these 2D heterostructures for controlling chiral spin structure and magnetic domain-wall based storage, memory and logic devices.

1Thin Film Laboratory, Dept. of Physics, IIT Delhi, Hauz Khas, New Delhi 110016, India.

References:(1) E. Dzyaloshinskii, Sov. Phys. JETP, 1957, 5, 1259.(2)A. K. Chaurasiya, S. Choudhury, J. Sinha and Anjan Barman, Phys. Rev. Appl., 2018, 9,014008.(3) H. Yang, G. Chen, A. A. C. Cotta, A. T. N’Diaye, S. A. Nikolaev, E. A. Soares, W. A. A.Macedo,K. Liu, A. K. Schmid, A. Fert, and M. Chshiev, Nat. Mater., 2018,17, 605.

P3.03. Computer Prediction of New Magnetic DoublePerovskite Compounds

Anita Halder and Tanusri Saha-Dasgupta

We searched new magnetic materials among yet-to-be synthesized Rh based double per-ovskites, Sr(Ca) 2 BRhO 6 (B = Cr, Mn, Fe). For this purpose we used a combination ofnumerical techniques involving genetic algorithm, density functional theory (DFT) and finitetemperature Monte Carlo simulations of DFT derived spin Hamiltonian. Interestingly, outof them, four compounds were found to be half metallic ferromagnet and rest were found toform rare example of antiferromagnetic metals. We also provided a prescription for growthconditions which may be helpful for future synthesis. [1] Continuing on the same theme, weemployed machine learning (ML) algorithm for screening of new stable double perovskite can-didates among the possible combination of 3d transition metal at B site and 4d/5d at B’ sitewhich are generally found to be magnetic. The adapted ML scheme is shown in the figure below.Our study predicted 33 new compounds, among which the electronic and magnetic propertiesof 25 compounds were studied extensively in this work. Our analysis predicted 21 compoundsto be magnetic with a wide range of magnetic and electronic properties, 7 compounds werepredicted as ferromagnetic half-metal, 6 compounds as ferrimagnetic insulator, 5 compoundsas antiferromagnetic insulator, 2 compounds as ferromagetic metal and one compound wasfound to be uncommon example of antiferromagnetic metal. [2]

References:(1) Computer Predictions on Rh-based Double Perovskites with Unusual Electronic and Mag-netic Properties. Anita Halder, Dhani Nafday, Prabuddha Sanyal and Tanusri Saha-Dasgupta,npj Quantum Materials, 3, 17 (2018).(2) Machine-learning assisted prediction of magnetic double perovskites. Anita Halder, Aish-waryo Ghosh and Tanusri Saha-Dasgupta, Physical Review Materials 3,084418(2019).

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P3.04. Family of lead halide perovskite as new generationhigh sensitive solid state gas sensor

Avisek Maity and Barnali Ghosh (Saha)

In recent days, search of new materials for solid state thin film gas sensor to detect toxicpollutants, particularly using nano material for their enhanced functionality is considerablecurrent interest. Family of perovskite halides is popular as photovoltaic and optoelectronicmaterial [1].We have recently found highly sensitive and highly selective room temperatureammonia gas (NH3) sensors can also be made from nano and micro structured lead halideperovskites with different cations and anions. The paper based CH3NH3PbBr3 (MAPB), CH(NH2)2PbI3 (FAPI) sensors are solution grown; that could trace NH3 gas rapidly by a visualcolor change as well as electrical resistance change [2, 3]. MAPB shows a color change fromorange to white and FAPI and MAPI from black to yellow under NH3 gas exposure respectively.During exposure to ammonia ( 30 ppm NH3 gas) roughly one order current increment in theperovskite halide paper sensors has been observed. For a fixed concentration (20ppm) of NH3gas, the sensitivity of MAPI is 96%, MAPB is 82% and 65% for FAPI. As the sensors, has beenfabricated by simple solution process, using cheap paper substrate and operable at ambienttemperature, hence compatible with very low power ( nW) paper electronics. Thus, the familyof lead halide perovskites may act as next generation solid state gas sensor in a cost effectivemanner for rapid and selective detection of ammonia for room temperature operation.

References:(1.) Salim, T. et al. Perovskite-based solar cells: impact of morphology and device architectureon device performance, J. Mater. Chem. A. 3, 8943–8969 (2015)(2.) Maity,A, Raychaudhuri, A.K , Ghosh, B: High sensitivity NH3 gas sensor with electricalreadout made on paper with perovskite halide as sensor material Sci. Rep., 9,7777 (2019)(3.) Maity, A and Ghosh, B: Fast response paper based visual color change gas sensor forefficient ammonia detection at room temperature. Sci. Rep., 8, 16851 (2018)

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P3.05. Growth and Electronic structure of SemiconductorNanoplatelets

Shivam Mishra and Priya Mahadevan

CdS, CdSe are semiconductors which favour three-dimensional structures and occur ineither the zinc- blende or the wurtzite phase. Recent advances have allowed for the formationof nanoplatelets of these materials which are just a few monolayers thick [1]. Although theseare grown by colloidal chemistry methods, one finds an extremely narrow full width at halfmaximum associated with their photoluminescence spectra. The thickness are also found torange from 4 to 11 layers. This level of precision in the growth allows one to examine quantumwell physics in the absence of a substrate. The reasons allowing for nanoplatelet formation aswell as the evolution of the electronic structure would be presented.

References:(1) S.Ithurria , M.D.Tessier , B.Mahler , R.P.S.M.Lobo , B.Dubertret and A.L. Efros , NatureMaterials 10, 936-41, (2011)

P3.06. Ultrafast Magnetization Dynamics andConfigurational Anisotropy in Triangular Shaped

Ferromagnetic Antidot Lattice with Varying SymmetryAnulekha De, Sucheta Mondal, Sourav Sahoo, Koustuv Dutta and Anjan Barman

Ultrafast magnetization dynamics in lithographically patterned nanoscale antidot magnoniccrystals have attracted interest to the scientific community due to their rich physics and poten-tial applications in magnetic memory, sensors, logic and on-chip communication devices [1].Here, we present the efficient modulation of optically induced SW spectra in 200-nm wide trian-gular shaped Ni80Fe20 antidot lattices (ADL) arranged in different symmetry, namely square,rectangular, hexagonal, honeycomb and octagonal symmetry with different lattice constants of400, 500, 600 and 700 nm. Further, the anisotropy properties of the square and octagonallattices have been studied by varying the orientation of the in-plane bias magnetic field. Theobserved tunability of the magnetization dynamics and the configurational anisotropy is due tothe inhomogeneous internal magnetic fields created by the asymmetric demagnetized regionsaround the triangular holes. Experimental studies with Time-Resolved Magneto-Optical KerrEffect (TR-MOKE) microscopy [2] show a rich variation of the SW spectra with the varia-tion of the lattice symmetry as well as the lattice constant. The SW modes in both squareand octagonal lattices possess strong anisotropic behaviour as a function of the in-plane biasfield orientation. The square lattice shows a four-fold anisotropy with superposition of a weakthree-fold anisotropy. On the other hand, for the octagonal lattice a mixture of eight-fold andthree-fold anisotropy is observed. Micromagnetic simulations [3] qualitatively reproduce the

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experimentally observed modes and the simulated mode profiles reveal the presence of differenttypes of extended and quantized standing SW modes in these samples. The simulated magneto-static field distributions underpinned the observed variation in the SW spectra leading towardsan extensive understanding of SW dynamics in this new type of magnonic crystal.

References:(1) A. Barman et al., Solid State Phys. 65 (2014) 1.(2) A. Barman et al., Phys. Rev. B 79 (2009) 144415.(3) A. De et al., Beilstein J. Nanotechnol. 9 (2018) 1123.

P3.07. Facet Modulation In Perovskite NanocrystalDebayan Mondal and Priya Mahadevan

II-VI semiconductor nanocrystals have been extensively studied by soft chemistry method.In addition to a control on the size, one has found modulation of the shape under various ex-perimental conditions.While experiments on hybrid perovskites have found only cubic facets ,recently it was shown that under certain experimental conditions one found a faceted polyhe-dron which could be transformed into a hexapod for CsPbX3 (X= Br,Cl) [1]. We will presentour recent theoretical studies which explain the shape modulation that take place. The stabilityof certain facets helps us to modulate the emissive properties of Mn(II) doped nanocrystalswhich will be discussed.

References:(1) Lucheng Peng, Sumit Kumar Dutta, Debayan Mondal, Biswajit Hudait,Sanjib Shyamal,Renguo Xie, Priya Mahadevan, and Narayan Pradhan. J. Am. Chem. Soc., 141, 40, 16160-16168 (2019).

P3.08. Spin-Peierls Transition in the Dimer Phase of theJ1 - J2 Model

Sudip Kumar Saha , Manoranjan Kumar and Z. G. Soos1

The spin-Peierls transition is modeled in the dimer phase of the spin-1/2 chain with antifer-romagnetic exchanges J1,J2 = αJ1 between first and second neighbors in the J1J2 model withvariable frustration 0 α 0.50 [1]. The parameters J1 = 160 K, α = 0.35 and a lattice stiffness

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account for the magnetic susceptibility of CuGeO3 , its specific heat anomaly, and the tempera-ture (T) dependence of the lowest gap. J1 = 79 K, J2 = 0 explains the susceptibility for organicT T F −CuS4C4(CF3)4. We have used a hybrid approach [2] using exact diagonalization (ED)and density matrix renormalization group (DMRG) where the thermodynamic limit at high T isreached by exact treatment of short chains followed by DMRG calculations of the low-energystates of progressively longer chains .

1Princeton University, Princeton, New Jersey.

References:(1) S. K. Saha, M. Kumar, Z. G. Soos, arXiv:1907.05724.(2) S. K. Saha, D. Dey, M. Kumar, and Z. G. Soos, Phys. Rev. B 99, 195144 (2019).

P3.09. Size dependent optical properties of MoS2nanoparticles and their photocatalytic applications

Didhiti Bhattacharya, Samit K Ray and Rajib K Mitra

While two dimensional layered MoS2 nanosheets have been extensively studied owing to theirfascinating optoelectronic properties, less attention has been paid on the corresponding zero-dimensional nano-crystals. In this contribution, we report the efficacy of MoS2 nanocrystals fortheir size tunable properties for optical and photocatalytic applications. We have synthesizeddifferent sized (10-70 nm), crystalline, hexagonal 2H-MoS2 nanoparticles (NPs) dispersed inDMF solvent using a simple exfoliation technique. Synthesized NPs are found to exhibit sizedependent optical properties and excitation dependent fluorescence characteristics in the vis-ible region, which are not observed in bulk or 2D MoS2 layers. Size tunable band gap andbroad absorbance and emission spectrum covering the visible range could be exploited in thefabrication of various opto-electronic devices. Charge carrier emission dynamics of differentsized MoS2 NPs are investigated using time correlated single photon counting (TCSPC) spec-troscopic technique. We found two time components, one in the order of several hundreds of ps,which arises due to the radiative recombination of charge carriers, while the other one is of theorder of a few ns, which emanates from the defect states of MoS2 NPs. The average time con-stants are found to decrease with increase in particle size. A noticeable photocatalytic activityof the synthesized MoS2 NPs under visible light illumination for the degradation of BrilliantGreen dye is also demonstrated for the first time and the effect of size variation of NPs in thedye degradation process is reported.

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P4.01. A Novel Nanohybrid for Potential Utilization in NIRPhotocatalysis: A combined experimental and DFT Study

Tuhin Kumar Maji, Debjani Karmakar1 and Samir Kumar Pal

Utilization of full solar spectrum to minimize the energy crisis is of major importance nowa-days. Solar light driven photocatalysis is one of the prime interests for efficient conversion ofsolar light. Solar light consists of 4% UV, 46% Visible and 50% near infrared (NIR) lights. Thedifficulty of NIR usage is its associated low energetic photons, which can lead to exciton gener-ation only for low band-gap semiconducting systems, which shows low yield in photocatalyticprocess. Moreover low bandgap systems pose very fast charge recombination process. Form-ing a heterostructure with one low band gap semiconductor and wide bandgap semiconductorcould be an option to overcome the problems. Herein, we report a novel CuS-ZnO nanohybrid,attached by a cysteine ligand, to exhibit efficient photocatalytic performance using the NIRpart of the solar light spectrum. Picosecond resolved studies and raman spectroscopy havebeen utilized to confirm the formation of the nanohybrid. We have observed an improved pho-tocatalytic activity towards degradation of methyl orange (MO) by the nanohybrid compared toits pristine counterparts under NIR light illumination. Ab initio studies have been carried outin DFT framework to obtain the insight to the photocatalytic process. Theoretically predictedband alignment indicates that the newly synthesized nanohybrid forms a type II heterojunction.An increment of significant charge separation from the conduction band of CuS to those of ZnOis the key mechanism behind the enhanced photocatalysis. This material can be very muchuseful to harvest NIR light efficiently..

1Technical Physics Division, BARC, Mumbai -700106, India.

Reference: T.K.Maji et al., App. Catal. A: Gen., 583, 117124 (2019).

P4.02. Molecular dynamics simulation study of dielectricproperties of molten acetamide:System size effect and model

dependenceDhrubajyoti Maji and Ranjit Biswas

A series of molecular dynamics simulation runs have been performed in order to study staticand dynamic dielectric properties of molten acetamide (CH 3 CONH 2 ) at 358.15 K. Two dif-ferent versions of optimized potentials for liquid simulation (OPLS) force field models, namelyOPLS-UA and OPLS-AA, have been used to compare their efficiency in calculating dielectricproperties, consistent with experimental results. As dielectric properties are results of collec-tive dynamics, a sufficiently large system is required to obtain reliable results. In this purposethree systems consisting of 250,500 and 1000 molecules have been studied. Minimal system

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size dependence has been observed as all three systems produce similar results. When forcefields are compared, OPLS-UA model is susceptible to capture static dielectric properties likestatic dielectric constant or average dipole moment pretty encouragingly whereas OPLS-AAmodel underestimates these values quite largely. On the other hand, OPLS-AA model predictsabout the dielectric relaxation dynamics better than OPLS-UA model..

P4.03. Nonequilibrium thermodynamics of Turing-Hopfinterplay in presence of cross diusion

Premashis Kumar and Gautam Gangopadhyay

A complete nonequilibrium thermodynamic framework is system- atically considered for study-ing dynamical instabilities in an open non- linear system. This kind of description is valid be-yond conventional Turing pattern[1, 2, 3] in presence of cross diusion. The main focus of ourstudy is to measure the entropic and energetic cost of pat-tern formation arising due to Turing-Hopf interplay[4, 5, 6]. This ap- proach is powerful enough to reveal how Hopf instability canbe uti- lized to dictate a stationary concentration prole and the possibility of nonequilibriumphase transitions. We have analyzed dierent scenar-ios of Turing-Hopf interplay in prototypicalreaction-diusion system, the Brusselator model[7, 8] through the relevant complex Ginzberg-Landau equation[1] using Krylov-Bogoiubov averaging method[9]. It is found that the crossdiusion coecients can generate a huge change in thermodynamic entities.

References:(1) Michael Cross and Henry Greenside. Pattern Formation and Dynamics in NonequilibriumSystems. Cambridge University Press, Cambridge, 2009.(2) A M Turing. The Chemical Basis of Morphogenesis. Philosophical trans- actions of theRoyal Society of London. Series B, Biological sciences, 1952.(3) James Dickson Murray. Mathematical Biology II: Spatial models and biomedical applica-tions, volume 2. Springer, 2003.(4)De Wit A, Lima, Dewel, and Borckmans. Spatiotemporal dynamics near a codimension-two point. Physical review. E, Statistical physics, plasmas, uids, and related interdisciplinarytopics, 54(1):261271, 7 1996.

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P4.04. High-resolution spectroscopic investigation of 13Cisotope of methane using cavity ring-down spectroscopy

coupled with EC-QCL at 7.5 µmBiswajit Panda, Sanchi Maithani, Abhijit Maity and Manik Pradhan

The spectral lines of 13C isotope of methane plays an important role in remote sensing andradiative heating problems concerning the atmospheres of the outer planets and terrestrialatmosphere (1). The accuracy of the determination of the thermal structure (composition ofthe atmosphere) is strongly related to the accuracy of the spectroscopic parameters like inten-sity,broadening coefficients of the absorption bands (2). As there are large vertical temperaturevariations in the atmosphere of the Earth and outer planets, high accuracy measurements ofthe temperature dependence of molecular absorption line shapes and spectroscopic line pa-rameters are required for precise atmospheric sounding of these atmospheres (3). In this inves-tigation, to best of our knowledge we are going to report the study of 13C isotope of methaneusing Cavity ring-down spectroscopy (CRDS) with external cavity (EC) quantum cascade laser(QCL). We have done this experiment using our lab developed set up by calibrated gas mixtureof 13CH4. We have explored 22 interference free high resolution spectral lines of 13CH4 andcalculated their absorption cross-section which matched well with HITRAN database. There-after, we studied the pressure broadening effect which is act as a window to study the interactionpotential of other molecules with 13CH4 in the atmosphere. Then we have investigated the tem-perature effect on 13CH4 and also calculated the temperature dependence exponent which waswell agreement with HITRAN value. So, we have experimentally done the precise measurementof spectroscopic parameters in our developed setup which have the potential to be applied inapplication field in near future for the further investigation.

References:(1) P. Varanasi, S. Chudamani, J. Geophys. Res., V (94) 175-178, (1989)(2) A. Chedin, N. Husson, N. A. Scott, D. Gautier, J. Mol. Spectrosc., 71,343-368, (1978).(3) D. Mondelain, C.C Peyret, W. Deng, S. Payan, A.W. Mantz, Appl. Phys. B 90. 227-233(2008)

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P4.05. Deciphering the Response of Asymmetry inHydrophobic Chains of Novel Cationic Lipids towards

Biological FunctionDipanjan Mukherjee and Samir Kumar Pal

Cationic liposomes are most promising among the non-viral vectors for delivery of nucleic acidin cell transfection. Variation in the molecular architecture of di-alkyl, dihydroxy ethyl ammo-nium chloride based cationic lipids involving hydrophobic tails have been found to influencetheir cell transfection efficacy. For example, liposomes based on a cationic lipid (Lip1814) hav-ing asymmetry in hydrophobic chains was found to display higher transfection efficacy in cul-tured mammalian cell lines than those comprising symmetric Lip1818 or asymmetric Lip1810.The effect of variation in the molecular architecture of the cationic lipids on the activity ofliposomes in terms of cell transfection efficiency have been explored via photophysical stud-ies of 8-anilino-1-naphthalenesulphonate (ANS) and Nile Red (NR) in three cationic liposomesof Lip1810, Lip1814 and Lip1818. Time-resolved fluorescence employing ANS have revealedreduced hydration of the lipid-water interface and enhanced relaxation dynamics of surfacewater (lipid headgroup bound water molecules) for Lip1810 and Lip1814 based liposomes inpresence of cholesterol. As the probe ANS fails to incorporate in the lipid-water interface ofLip1818 based liposomes due to their significantly high rigidity, no information concerning ex-tent of hydration of the lipid-water interface or interfacial water dynamics could be obtained.Time-resolved polarization-gated anisotropy measurements of NR in presence of cholesterolhave revealed rigidity of the cationic liposomes to be in the increasing order of Lip1810 <Lip1814 < Lip1818. In presence of cholesterol moderately higher rigidity, reduced membranehydration and enhanced relaxation dynamics of the interfacial water molecules give rise tosuperior cell transfection efficacy of Lip1814 based cationic liposomes than highly flexibleLip1810 or highly rigid Lip1818.

Figure 1: Schematic representation of rigid Flexibility of three different lipids in presence Andabsence of cholesterol.

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Reference:(1) M. Ramezani, M. Khoshhamdam, A. Dehshahri and B. Malaekeh-Nikouei, Colloids Surf.,2009, 72, 1-5.

P4.06. A Redox Modulatory Mn 3 O 4 Nanozyme withMulti-Enzyme Activity for Dual Therapy; Route of

Administration Plays the MagicAniruddha Adhikari and Samir Kumar Pal

Chronic liver diseases (including hepatic fibrosis and cirrhosis) are the fifth most commoncause of death, affecting around 400 million people per year worldwide and have no effectivemedication. Our goal was to improve treatment outcomes for hepatic fibrosis by designingnanoparticles with therapeutic efficacy. Thus, citrate functionalized Mn 3 O 4 nanoparticles(C- Mn 3 O 4 NPs) were developed, characterized and tested on preclinical mice model ofhepatic fibrosis. Oral treatment of C-Mn 3 O 4 NPs ( 6 nm, spherical) efficiently reverses thefibrotic damages from stage 4 to stage 1 (Ishak). -SMA and hepatic hydroxyproline content de-creased significantly, along with improvements of other liver function parameters. Retrieval ofcellular antioxidant defense system (SOD, catalase, GSH etc.) upon C-Mn 3 O 4 NP treatmentindicated the underlying therapeutic mechanism to be antioxidant dependent. This was furthersupported by investigations that revealed its modulatory activity on mitochondria, the cellularmediator of oxidative stress. The twist in tale comes when the rout in administration changesto injection (i.p. or i.v.). The same NPs show ultrahigh efficacy in symptomatic treatmentof neonatal hyperbilirubinemia. It can directly degrade bilirubin in vivo by 80without vary-ing other liver function parameters. This is particularly important because, elevated level ofbilirubin and its oxidative products in human blood causes severe neurotoxic diseases (neona-tal jaundice, Gilbert syndrome, Crigler–Najjar type I disease, bilirubin induced neurologicdysfunction etc.) some of which may even lead to morbidity and mortality. Most importantly,there is no medicine available in the market that can directly reduce neonatal bilirubin level ina symptomatic way. Thus C-Mn 3 O 4 NPs is the first inorganic nanoparticle that can efficientlytreat hepatic fibrosis without any delivery vehicle in preclinical mice model when administeredorally. Interestingly, if the rout of administration changes to injection, the same nanoparticlecan treat neonatal hyperbilirubinemia in a fast and symptomatic way. Thus this study may openup a fascinating way for quicker, safer and efficient treatment of neonatal hyperbilirubinemia,replacing phototherapy.

References:(1) A. Adhikari et. al. “Citrate Functionalized Mn3O4 in Nanotherapy of Hepatic Fibrosis byOral Administration”, Future Science (OA) 2016 2 FSO146.(2) N.Polley et. al.“Safe amp Symptomatic Medicinal Use of Surface Functionalized Mn3O4Nanoparticles for Hyperbilirubinemia Treatment in Mice”, Nanomedicine 2015 10 2349.

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P4.07. Correlation Between Protein Bond Vector andDihedral Fluctuations

Abhik Ghosh Moulick and Jaydeb Chakrabarti

Coordination between residues of protein is essential for various biophysical phenomena. Thecoordination can be best understood in terms of the correlation between dihedral angles ofthese residues. Since these fluctuations take place at nanoseconds time scale, they are experi-mentally not easily accessible. NMR experiments probe bond vector fluctuations given in termsof cross correlated relaxation (CCR) rates. Theoretically, this CCR rates can be expressed aslow frequency ( 0) limit of the spectral function of these fluctuations. Here we illustrate thecorrelation between protein bond vector and dihedral angle using molecular dynamics simula-tion of a small protein ubiquitin. We compute the spectral function for both kinds of fluctuationsand find a good correlation. We also calculate CCR rates between protein bond vector fromsimulation and compare with CCR data obtained from NMR experiments. A good correlationbetween theoretical and experimental values is found. Hence our work may provide an indirectway to set up a connection between theoretical and experimental result.

P4.08. Novel One Pot Synthesis and SpectroscopicCharacterization of Folate-Mn3O4 Nanohybrid for Potential

Photodynamic Therapeutic ApplicationSusmita Mondal and Samir Kumar Pal

Treatment of cancer using nanoparticles made of inorganic and metallic compounds have beenincreasingly used, owing to their novel intrinsic physical properties and their potential to in-teract with specific cellular sites, thereby significantly reducing severe secondary effects. Inthis study, we report a facile strategy for synthesis of folate capped Mn3O4 nanoparticles (FA-Mn3O4 NPs) with high colloidal stability in aqueous media using a hydrothermal method forpotential application in photodynamic therapy (PDT) of cancer. The capping of FA to Mn3O4NPs was confirmed using various spectroscopic techniques. In adenocarcinomic human alveo-lar basal epithelial cells (A549), the nanohybrid synthesised in combination of FA and Mn3O4shows remarkable PDT activity via intracellular ROS generation (singlet oxygen). As estab-lished using DNA fragmentation assay and fluorescence studies, the nanohybrid can causesignificant nuclear DNA damage by light induced enhanced ROS generation. Assessment ofBax, Bcl2 provides strong evocative evidence of apoptotic cellular death.

Cumulatively, the outcomes of this study suggests that this newly synthesized FA-Mn3O4NPs can specifically destroy cells with overexpressed folate receptors, and thereby providingan inevitable solution in the journey of cancer eradiation.

Reference:(1) Susmita Mondal, Aniruddha Adhiakari, Monojit Das, Soumendra Darbar, Saleh A. Ahmed,

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Figure 2: FA-Mn3O4 invades in cancer cells via over expressed folate receptors on cancer cellsurface and generates ROS which induces apoptotic death in cancer cells via several cellularsignaling.

Ahmed Alharbi, Siddhartha Sankar Bhattacharya, Debasish Pal, Samir Kumar Pal, RCS Adv.9, 30216-30225, (2019).

P4.09. A model to understand formation of soret colloidalcrystal

Rahul Karmakar and Jaydeb Chakrabarti

In our calculation, there is a three-dimensional box full of colloidal particles interact-ing through Lenard Jones(LJ) potential in a temperature bath. We perform Brownian dy-namics simulation. We choose a point from the reported equilibrium phase space diagramof LJ particle. After equilibration at a higher temperature, we cool half of the box sud-denly. We study local bond order parameters to check crystallization. These parameters al-low to distinguish between liquid and crystal local ordering around a particle. It is definedas[3],ql(i) = 1

Nb(i) ∑m ∑ j Ylm(θi j,φi j). Ylm are the spherical harmonics. (θi j,φi j) are orientationof bond between particle i and it’s neighbour j and the sum runs over all neighbours Nb(i). Forour system we take l = 6. In crystal phase q6 ≈ 1.0 and q6 ≈ 0 for liquid. We find crystalliza-tion in the colder region. We observe that crystallization in the colder region increases withtime after creating the temperature difference in the system. We also observe dynamic densityprofile in the systemThermophoresis is a process, where particles migrate along the temper-ature gradients in the system. It is a non-equilibrium phenomenon. The phenomenon in thecontext of colloids is also called the Soret effect. It is seen from different experimental studiesthat particles can diffuse from hot to cold temperature and also vice versa[1], depending uponthe particle-solvent microscopic interaction. In a recent experiment[2], it is seen in nanoparti-cles to form crystal from the aqueous nanoparticles solution in the colder region of the system.

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These crystals are called the soret crystal due to formation by temperature difference. Here westudy soret crystal formation through numerical simulation.

In our calculation, there is a three-dimensional box full of colloidal particles interact-ing through Lenard Jones(LJ) potential in a temperature bath. We perform Brownian dy-namics simulation. We choose a point from the reported equilibrium phase space diagramof LJ particle. After equilibration at a higher temperature, we cool half of the box sud-denly. We study local bond order parameters to check crystallization. These parameters al-low to distinguish between liquid and crystal local ordering around a particle. It is definedas[3],ql(i) = 1

Nb(i) ∑m ∑ j Ylm(θi j,φi j). Ylm are the spherical harmonics. (θi j,φi j) are orienta-tion of bond between particle i and it’s neighbour j and the sum runs over all neighbours Nb(i).For our system we take l = 6. In crystal phase q6 ≈ 1.0 and q6 ≈ 0 for liquid. We find crystal-lization in the colder region. We observe that crystallization in the colder region increases withtime after creating the temperature difference in the system. We also observe dynamic densityprofile in the system.

References:(1) Why molecules move along a temperature gradient: S. Duhr, D. Braun, DOI: 10.1073/pnas.0603873103,PNAS 2006(2) M. Moronshing and C. Subramaniam,DOI: 10.1021/acssuschemeng.8b02050, 2018(3) Simulation of homogeneous crystal nucleation close to coexistence: P. Ten-Wolde, M. J RuizMontero, D. Frankel, Faraday Discussions,1996

P4.10. Enhanced Water Stability and Photoresponsivity inMetal-Organic Framework to Combat Drug-resistant Bacteria

Md Nur Hasan and Samir Kumar Pal

Multidrug resistance of bacteria is a significant threat to general wellbeing. Its extraordinaryincrement calls for quick alternative medical strategies to prevent from those bacteria. In thispresent work, we have successfully synthesized a bimetallic (Zinc and Cobalt) Zeolitic Imi-dazolate Framework (Zn50Co50-ZIF), a class of more extensive microporous Metal-OrganicFramework1. The combined nanostructures keep up both water stability like ZIF-8 (exclusivelyZn containing) and charge transfer electronic band in the visible optical range as ZIF-67 (ex-clusively Co containing). Precious Crystal structure from XRD, high resolution transmissionelectron microscopy followed by elemental mapping confirm structural intrigity and omnipres-ence of the metal atoms (Zn and Co) across the nanomaterial with equivalent percentage. Pres-ence of charge transfer state reliable with ZIF67 and complete ultrafast excited state dynamicsof the imidazolate moiety in both ZIF-8 and ZIF-67, is evidenced from steady state and time-resolved optical spectroscopy. The thermal and aqueous stabilities of Zn50Co50-ZIF are foundto be better than ZIF-67 but analogous to ZIF-8 as evidenced by solubility, scanning electronmicroscopy and XRD studies of the material in water. We have evaluated the photoinduced

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reactive rxygen rpecies (ROS) generation capability by the mixed ZIF using dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. We have also explored the potentiality of the syn-thesized material for the substitute remediation of methicillin resistant Staphylococcus aureus(MRSA) infection through the ROS generation and methylene blue (MB) degradation kinetics..

Figure 3: Schematic representation of synthetic strategy for mixed metal zeolitic imidazolateframework.

Reference:(1) Long, Jeffrey R., and Omar M. Yaghi. ”The pervasive chemistry of metal–organic frame-works.” Chemical Society Reviews 38.5 (2009): 1213-1214.

P4.11. Fluorescence Dynamics in Polymer Gel ElectrolytesKajal Kumbhakar and Ranjit Biswas

Efforts are now being increasingly focused on research and development of new materialsthat would be useful in the energy sector. Exotic materials for rechargeable batteries oc-cupy the central focus in this domain. Polymer gel electrolytes (PGEs) are promising can-didates for use in energy storage devices, super capacitors, dye-sensitized solar cells, fuelcells etc. We explore interaction and relaxation dynamics of PGEs consist of lithium perchlo-rate (LiClO4), propylene carbonate (PC) and polypropylene glycol (PPG425), having compo-sition [(PC+LiClO4)+wt%PPG425], via steady state and time-resolved fluorescence (TRF)spectroscopy. Coumarin 153 (C153) and trans2-[4-(dimethyl amino) styryl] benzothiazole(DMASBT) are two external fluorescent dyes employed as local reporters. Steady state ab-sorption and fluorescence of C153 in these PGEs indicate substantial blue shift with increasingpolymer concentration. DMASBT reports spatial heterogeneity in these systems, while C153

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does not report such spatial inhomogeneity. TRF measurements using C153 reveal the ex-istence of temporal heterogeneity in the medium via fractional power dependence of solute(C153) rotational time on medium viscosity, shown in Fig. 1. Surprisingly, average solvationtimes measured with C153 shows viscosity dependence completely opposite to that found fromrotation times. This decrease of average solvation times with viscosity might have arisen fromthe increased participation of –OH groups with successive addition of polymer (PPG425).

References:(1) Armand, M.; Tarascon, J.-M. Nature 2008, 451, 652.(2) Tarascon, J.-M.; Armand, M. Nature 2001, 414, 359(3) Lu, Y.-C.; Xu, Z.; Gasteiger, H. A.; Chen, S.; Hamad-Schifferli, K.; Shao-Horn, Y. J. Am.Chem. Soc.2010, 132, 12170.(4)Simon, P.; Gogotsi, Y. Nat. Mater. 2008, 7, 845.(5) Ogasawara, T.; Debart, A.; Holzapfel, M.; Novak, P.; Bruce, P. G. J. Am. Chem. Soc. 2006,128, 1390

P4.12. Solute and Solvent Dynamics in Neat, and Wet-Octanol:Steady State and Time Resolved Fluorescence Measurements

Narayan Chandra Maity, Jayanta Mondal, Kajal Kumbhakar and Ranjit Biswas

Neat 1-octanol and wet-octanol has been the subject of numerous studies due to their propertyof membrane mimics. Interaction and dynamics of different external fluorescent solutes in neatand wet-octanol and as well as solvent dynamics have been investigated via steady state andtime-resolved fluorescence (TRF) measurements in the temperature range of 283 ≤ T/K ≤ 323with various mole fraction of water (XH2O = 0 to 0.20) in the octanol rich region. Coumarin 153(C153), Coumarin 343 (C343), trans-2-[4’- (dimethylamino)styryl]benzothiazole DMASBThave been employed to investigate solutecentre reactive and non-reactive relaxation dynamicsin this aqueous mixture. Excitation wavelength dependence of fluorescence emissions, suggestthat both the neat and aqueous binary mixtures, within the lifetime of C343 (< τli f e > 3−4ns)and DMASBT (< τli f e > 0.5 ns), are spatially heterogeneous. Fluorescence anisotropy studieswith C153 and C343 in neat and wet-octanol have been used to explore the solute-mediumfrictional coupling. Inspite of nearly same size, rotation dynamic of C153 shows fractionalviscosity dependence while C343 nearly follows the Stoke-Einstein-Debye model. Dynamicfluorescence stoke shift measurements detected fast (sub-nanosecond) and slow (nanosecond)solvent relaxation time scale in these media..

References:(1) S. E. Debolt, P. A. Kollman, J. Am. Chem. Soc., 5316-5340, 117( 1995).(2) S. A. Best, K. M. Merz, C. H. Reynolds, J. Phys. Chem. B, 714-726, 103 (1999).

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(3) J. L. MacCallum, D. P. Tieleman, J. Am. Chem. Soc. 15085-15093, 124 (2002).(4) Z. Hu, C. J. Margulis, PNAS , 831-836, 103(4) (2006).(5) P. K. Mandal, M. sarkar, A. Samanta, J. Phys. Chem. B, 9048-9053, 108 (2004)(6) S. Koley , H. Kaur and S. Ghosh, Phys. Chem. Chem. Phys. 22352, 16 (2014).(7) M. Kondo, X. Li, M. Maroncelli, J. Phys.Chem. B, 12224–12233, 117( 2013).

P4.13. Evanescent-wave based cavity ring-down spectroscopy tostudy interfacial kinetics of condensed phase molecules

Sanchi Maithani, Abhijit Maity and Manik Pradhan

Cavity ring-down spectroscopy (CRDS) is a high-sensitive technique wherein the incidentlight is trapped in a high-finesse optical cavity. It is conventionally used to probe gas-phasemolecules [1]. However, by incorporating additional optics in the cavity, it can be utilized tostudy condensed-phase molecules as well [2]. In this work, we have developed an evanescent-wave (EW) based CRDS set-up at 644 nm to probe the interfacial kinetics of aggregatednanoparticles. The EW is generated through the total internal reflection condition (TIR) ontop of the prism, which is a part of an optical cavity composed of two high-reflectivity mir-rors. A pulsed laser (at 644 nm) was utilized as the light source and the exponential decay ofthe trapped light was observed using a photomultiplier tube (PMT). The set-up was character-ized in detail and several parameters were evaluated to obtain an optimized ring-down timeof ≈ 159 ns. This system was utilized to investigate the interfacial kinetics of the salt-inducedaggregation of gold and silver nanoparticles. The kinetic rates were evaluated and the adsorp-tion behavior of these aggregates was explored. We also studied the adsorption kinetics of aprotein-corona system of these nanoparticles and their effect on the resulting surface adsorp-tion. Therefore, we developed an EW based system to extend the high-sensitivity of CRDS tocondensed-phase molecules.

References:(1) M. Mazurenka, A. J. Orr-Ewing, R. Peverall, and G. AD Ritchie., Annual Reports Section”C”(Phys. Chem.), 2005, 101, 100-142.(2)M. Schnippering, S. RT Neil, S. R. Mackenzie, and P. R. Unwin., Chemical Society Reviews,2011, 40, no. 1: 207-220.

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P4.14. Interfacial Hydration Dynamics of Cationic/AnionicVesicles Studied by Time Resolved Fluorescence Technique

Sumana Pyne and Rajib Kumar Mitra

Vesicles play important roles in cell biology as can mimic liposomes and cell membranes 1 . Itis important to study the hydration dynamics of vesicle as it correlates with the mechanism howmembrane interacts with its surroundings. 2 In this study, we have prepared a model vesicle byusing anionic surfactant, SDS (Sodium dodecyl sulphate) and adding cholesterol (3β -Hydroxy-5-cholestene, 5-Cholesten-3β -ol) into it. From the DLS (Dynamic Light Scattering) measure-ments, we observe that when cholesterol is added in SDS micelles vesicles (diameter≈100 nm)are formed. We study the hydration dynamics in interfacial region of these systems using fluo-rescence spectroscopy using C500 (Coumarin 500) as the probe molecule. Emission intensityof C500 decreases in vesicle with increasing the cholesterol concentration compared to thatin micelles. Steady-state anisotropy of C500 increases upon the addition of cholesterol in thesystem, which indicates that it suffers more restricted environment in cholesterol/SDS vesi-cles. From the time resolved fluorescence study, we have constructed the TRES (Time ResolvedEmission Spectra) of C-500 in different vesicle systems, and we calculate the solvation time forindividual vesicle system and observe that the solvation time of probe molecule increases, i.e.the hydration dynamics get more restricted with increasing concentration of cholesterol.

References:(1) G. Bozzuto, A. Molinari, Int. J. Nanomedicine, 2015, 10, 975.(2) N. Watanabe, K. Suga, T.K.M. Nyholm, H. Umakoshi, Langmuir, 2019, 35, 6762.

P4.15. Exploration of Organic-inorganic nanohybrid toenhance the photostability and NIR activity of cyanine dyes for

their potential applicationsArpan Bera and Samir Kumar Pal

NIR (near infrared region) light induced photodynamic therapy has enormous importance foranticancer treatment. Some NIR cyanine dyes have achieved great success in imaging andtreating cancer, such as IR820. However, their clinical action is limited for restrict photosta-bility, considerable thermal degradation, short circulation times and nonspecific biodistribu-tion.[1] Our present study is an attempt to overcome some of these limitations by attachingIR820 with ZnO nanoparticles. We have prepared IR820-ZnO nanohybrid and characterised itusing microscopic and optical spectroscopic tools.

We have explored the enhancement of photostability of IR820 upon attachment on the ZnOsurface. The formation of IR820-ZnO nanohybrid reduces production of singlet oxygen and

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Figure 4: Schematic representation of the dynamics of ROS generation.

increases overall formation of reactive oxygen species under red light excitation. The DCFHassay and luminol chemiluminiscence demonstrates the greater formation of overall ROS andsuper oxide respectively for nanohybrid over IR820. We have also done the SOSGR assayand find the enhancement of singlet oxygen generation by IR820 over nanohybrid. The singletoxygen deficiency enhances the photostability of IR820 on ZnO surface. We have also exploredthe photoinduced excited state electron transfer process from LUMO of IR820 to conductionband of ZnO. This photo-electron transfer process enhances photostability and the productionof reactive oxygen species (ROS). A quencher of singlet oxygen (NaN3) was used to monitorthe dynamics of singlet oxygen as a ROS and as a destroyer of IR820. The thermogravimetricanalysis has shown the negligible thermal degradation of IR820-ZnO nanohybrid. Also, ZnOis able to deliver the IR820 dye selectively in tumour and cancer cells, as they have acidicenvironment. Our results provide a promising improvement to use IR820-ZnO nanohybrid inphotodynamic therapy.

References:Fernandez-Fernandez, A.; Manchanda, R.; Lei, T.; Carvajal, D. A.; Tang, Y.; Kazmi, S. Z. R.;McGoron, A. J., Comparative study of the optical and heat generation properties of IR820 andindocyanine green. Molecular imaging, 11 (2), 7290.2011. 00031, 2012.

P5.01. Light-induced excited spin-state trapping in spincrossover model system

Shiladitya Karmakar, Debashree Ghosh1 and Tanusri Saha-Dasgupta

Spin crossover (SCO) materials have drawn significant attention of the scientific communitydue to its diverse application possibilities, ranging from data storage to molecular electronics,to photomagnetism and nonlinear optics[1-3]. SCO mechanism can be observed in any octa-hedrally or tetrahedrally coordinated transition metal complexes with transition metal ions in

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d 4 -d 7 or d 3 -d 6 electronic configurations surrounded by flexible organic ligands. But thecommonly observed cases are that of octahedrally coordinated iron(II) complexes with Fe2+

ions in 3d 6 electronic configuration[2-4]. The spin state of Fe(II) ion switches between thediamagnetic low-spin (LS) S = 0 state and the paramagnetic high-spin (HS) S = 2 state inresponse to external stimuli such as temperature, pressure, applied magnetic field, and lightirradiation[5-7]. The phenomenon of switching from a stable LS state to metastable HS state,upon light irradiation, is known as light-induced excited spin-state trapping (light-induced ex-cited spin state Trapping; LIESST). We computationally investigate the light-induced excitedspin-state trapping (LIESST) in a spin crossover (SCO) model system, derived out of [Fe(abpt)2 (NCS) 2 ] (abpt=4-amino-3,5- bis(pyridin-2-yl)-1,2,4-triazole) consisting of Fe(II) SCO cen-ter coordinated by bidenate as well as monodentate ligands[8].

For this purpose, we use two complementary techniques: (a) time-dependent density func-tional theory (TDDFT) with the choice of different exchange-correlation functional and (b)multireference approach of complete active space self-consistent field and complete active-space second-order perturbation (CASPT2) theory. We calculate the potential energy curves(PECs) of low-energy states, as well as spin-orbit couplings at crossing points of these PECs.Inputting these pieces of information, and the information related to nuclear degrees of free-dom within the Franck-Condon theory, we compute the relaxation rates of possible LIESSTmechanisms, as suggested by the two approaches. Comparison of the computed rates of themodel system with that of the real systems leads us to conclude that TDDFT approach may bea cheap, yet not an unreasonable, approach to describe LIESST processes. This finding makesthe application of TDDFT to real complexes promising, which would involve handling complexstructures containing 100 to 200 atoms. In this context, it is worth mentioning that Hauser etal. determined the relaxation rates for a number of Fe(II) coordination compounds between 10and 270 K using time-dependent optical spectroscopy and showed that it can vary in a largerange of 12 orders of magnitude[9]. Calculation of relaxation rates of real complex may pro-vide microscopic understanding of the relationship between the structure and the relaxationrate. complexes, consisting of several tens to several hundreds of atoms, given its computation-ally inexpensive nature compared with that of the multireference approaches.

1School of Chemical Sciences,Indian Association for the Cultivation of Science, Kolkata, India.

References:

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(1) J. F. Letard, P. Guionneau, L. Goux-Capes, in Spin Crossover in Transition Metal Com-pounds I-III (Eds: P. Gutlich, H. Goodwinpp), Springer, Berlin, Germany 2004.(2) J. Linares, E. Codjovi, Y. Garcia, Sensors 2012, 12, 4479.(3) S. Cobo, G. Molnar, J. A. Real, A. Bousseksou, Angew. Chem. Int. Ed. 2006, 45, 5786.(4) T. Saha-Dasgupta, P. M. Oppeneer, MRS Bull. 2014, 39, 614.(5) S. Brooker, J. A. Kitchen, Dalton Trans. 2009, 7331. (6) S.-i. Ohkoshi, K. Imoto, Y.Tsunobuchi, S. Takano, H. Tokoro, Nat. Chem. 2011, 3, 564.(7) G. J. Halder, C. J. Kepert, B. Moubaraki, K. S. Murray, J. D. Cashion, Science 2002, 298,1762.(8) Karmakar S, Ghosh D, Saha-Dasgupta T. Light-induced excited spin-state trapping in spincrossover model system. Int J Quantum Chem. 2019;e26122.(9) A. Hauser, A. Vef, P. Adler, J. Chem. Phys. 1991, 95, 8710.

P5.02. Tunable internal resistance of piezoelectricnanogenerator for high performance output power generationSnehamoyee Hazra, Shubhamita Sengupta, Ankita Ghatak, A.K. Raychaudhuri1 and Barnali

Ghosh(Saha)

The development of piezoelectric nanogenerators with high output power generation inorder to drive microelectronic devices is a great challenge till now due to the high internalresistance of piezoelectric materials. In this work, the effect of electrode materials on thevoltage generation as well as the internal resistance of the nanogenerators have been stud-ied. Piezo-electric polycrystalline tetragonal nanowires of Pb(Zr0.52Ti0.48)O3 (PZT) grownby hydrothermal technique were used as the generating material. As an electrode materialnoble metal gold (Au) as well as copper (Cu) were used. It has been found that the voltagegenerated by using copper electrode is around ∼1 V. The copper electrode provide maximumvoltage generation having less potential barrier. The gold electrode in contact with the mate-rial provide a high contact resistance which increases the internal resistance. It has also beenobserved that a bilayer electrode (In-Ag) increases the voltage generation to 3.2 V and also thepower output enhances from 600 nW to 1µW with a concomitant reduction of internal resis-tance. An effective dependence on work function of the electrode material has been established.

1CSIR-Central Glass and Ceramic Research Institute, 196, Raja S C Mallick Rd, Kolkata.

References:(1) Xu S, Hansen BJ, Wang ZL. Piezoelectric-nanowire-enabled power source for driving wire-less microelectronics. Nature communications. 2010 Oct 19;1:93.

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P5.03. Development and validation of a non-invasivespectroscopic device for hemoglobin estimation of neonates at

point-of-careAmrita Banerjee and Samir Kumar Pal

Estimation of hemoglobin level in newborns is mandatory as per American Academy of Pe-diatrics (2004), to reduce incidents of neonatal anemia. Although invasive capillary collectionof blood and subsequent biochemical test is considered a gold standard for anemia detectionin neonates, blood hemoglobin measurement using various non-invasive instruments is alsoused sporadically across the globe. The major aim of this study was to develop a non-invasivespectrometry-based technique for measurement of neonatal hemoglobin level as an alternativeof blood test without limitations of other available hemoglobinometers.

P5.04. Adsorption of Mercury(II) from Aqueous SolutionsUsing Porous Organic Polymers

Kanika Kole and Subhra Jana

Toxicity of mercury in food is one of the challenging problem in the health and environ-mental sectors as it causes dreadful damage to human nerves, lungs, kidneys and other organsthough the bioaccumulation.1,2 Here, we have developed porous polymeric materials havingchelating pyrrole units in the pore walls to adsorb mercury from the aqueous solution. Thebottom-up synthesis approach is used for Friedel–Crafts polymerization of pyrrole in makingpolymeric materials PY-1 and PY-2. These porous materials demonstrate strong mercury ad-sorption affinity and the kinetics of adsorption depends on the adsorbate concentration as wellas the physical and chemical characteristics of the adsorbent. Among these porous materials,PY-2 shows high efficiency in removing mercury from aqueous solution with Hg(II) uptake ca-pacity of 145 mg g1. The high adsorption capacity facilitates rapid separation of Hg (II) fromaqueous solution, which in turn lowers the concentration well below the acceptable level indrinking water.

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P5.05. Heterogeneity of dynamics in modulated colloidSuravi Pal and Jaydeb Chakrabarti

The relation between structure and dynamics in colloids has been a topic of interest overseveral decades[1-4]. We address this for 2-D colloidal particles subjected to a spatially pe-riodic one diensional external potential[5] using Brownian Dynamics simulation[6, 7]. Thestatic density contour plot suggests uniform distribution of particles in absence of external po-tential. The system gets modulated in presence of the external potential. The more the potentialstrength, the more strongly pinned the particles are at the potential minima. We find MSDlinear in time in both parallel and transverse directions with the slopes being the diffusioncoefficients. The diffusion co- efficients decay exponentially with increasing potential strengthsuggesting constrained diffusion. The residence times of different particles show homogeneousmotion at small and large potential strength. Large variances in the residence times character-ize heterogeneous motion at intermediate potential strength. The density auto-correlations (selfVan Hove function)[8] show multiple probable location of particles, supporting heterogeneityin dynamics. This suggests non-Fickian diffusion[9] in the system.

References:(1) C. Bechinger and E. Frey, Phase behaviour of colloids in confining geometry, J. Phys.:Condens.Matter 13 R321 (2001).(2) J. Chakrabarti, H.R. Krishnamurthy, A. K. Sood, Phys. Rev. Lett. 75, 2923 (1994).(3) E. Frey and K. Kroy, Brownian motion:a paradigm of soft matter and biological physics,Ann. Phys. (Leipzig) 14, 20 (2005).(4) J. Chakrabarti, HR. Krishnamurthy, AK. Sood and S. Sengupta, Reentrant melting in laserfield modulated colloidal suspensions, Phys. Rev. Lett. 75, 2232 (1995).(5) C. Bechinger, M. Brunner, and P. Leiderer, Phase Behavior of Two-Dimensional ColloidalSystems in the Presence of Periodic Light Fields, Phys. Rev. Lett. 86, 930 (2001).(6) L. Ermak and Y. Yeh, Equilibrium electrostatic effects on the behavior of polyions in solu-tion: polyion-mobile ion interaction, Chem. Phys. Lett. 24, 243 (1974).(7) J. Chakrabarti, J. Dzubiella, and H. Lwen, Reentrance effect in the lane formation of drivencolloids, Phys. Rev. E 70, 012401 (2004).(8) J.-P. Hansen and Ian R. McDonald, Theory of Simple Liquids, Academic Press, 84 Theobald’sRoad, London WC1X 8RR, UK (2006).(9) S. Dutta and J. Chakrabarti, Anomalous Dynamical Responses in a Driven System, EPL(EurophysicsLetters), 116, 38001 (2016).

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P5.06. Towards the development of a spectroscopy basednon-invasive measurements of organ specific oxygen saturation

Neha Bhattacharyya and Samir Kumar Pal

Contemporary technologies used for monitoring oxygen saturation of the foetus has notbeen quite effective in reducing harm rates of the foetus in the intrapartum period. Neverthe-less, the adoption of such available techniques has significantly increased C-section deliveriesin modern society. The non- invasive monitoring of the oxygen saturation of the foetus usingoptical signals among other physiological conditions still remains questionable. Due to therealization of these limitations, we have developed an in-vitro electro-optic strategy utilizingthe principle of Kubelka Munk (K-M) theory of diffuse reflectance to extract selective colourinformation about a certain dye in presence of multiple staining agents. Our developed strat-egy was found to be effective in measuring specific information about a particular tissue buriedunder several layers of human tissue mimic. The experimental results were in well agreementin accordance with the K-M theory (r = 0.97). Furthermore, we have also demonstrated theefficacy of the set-up in a bio medical application which facilitates easy determination of thethickness of the nail plate by simply tweaking the optical parameters of the incident light.

P5.07. Use of photo-mechanical actuation of ferromagneticshape memory alloys in the area of interventional cardiology

Bishal Kumar Keshari, Gurdeep Singh, Indrajit Manna, Abhishek Bagchi and P. K.Mukhopadhyay

It was first observed in the year of 2012 that a ferromagnetic shape memory alloy (FSMA)shows photo induced micro actuation (PIMA) effect when subjected to a laser beam. Here atiny spot of focused laser beam of nominal power output of 100 mW was incident on a sample,it immedietly moves away and when the light was turned off it returns to its last position. ThisPIMA effect is a unique phenomenon and doesn’t have any parallel with any other known phe-nomenon. FSMA material has a large potential to be used as microactuator due to their abilityto generate mechanical work under the influence of thermal and magnetic stimuli. With thediscovery of PIMA effect a new method was introduced to effectively control the magnitude ofactuation of the microactuation system. As an example of such microactuator system a proto-type of a simple catheter made of FSMA is proposed in this study. A model was developed andits characteristics under different light source were systematically studied. One most importantparameter is its wavelength dependency of the incident laser light. Here we used three differ-ent coloured lasers and the actuation phenomenon was studied. An effective, new and uniquecontrolling mechanism for the production and operation in the field of intervention cardiologyhas been proposed here

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References:(1) Z. Hu, B. Rajini kant, R. Tamang, B. verghese, C. H. Haur and P.K. Mukhopadhyay, Smartmatter. Struct, Vol. 21 (2012), 032003.(2) A Bagchi, S Sarkar and P. K. Mukhopadhyay, Indian J. Phys (2018) 92: 883.

P5.08. A non-invasive technique to diagnose Helicobacterpylori infection exploiting human exhaled breath analysis withcomparison between Rapid Urease Test And 13 C Urea Breath

TestSwarnava Biswas, Sayoni Bhattacharya, Abhijit Maity, Sujit Chaudhuri1 and Manik Pradhan

Exhaled human breath consists of different types of volatile organic compounds (VOC)which have concentrations ranging from ppm (parts per million; 10 -6 ) to ppb (parts per bil-lion; 10 -9 ) level. Till now, more than thousand compounds have been identified in exhaledbreath. Some of these trace molecules can yield information about bio and physiological re-sponses in human body such as particular diseases and metabolic disorder, and hence theyare assigned as biomarkers for specific diseases. Therefore, the analysis of the breath sampleoffers a non-invasive technique to diagnose specific disease targeting the potential biomarker.Our aim is to exploit the breath analysis mechanism to detect gastrointestinal diseases whichare caused by Helicobacter pylori (H. pylori) bacteria. H. pylori is a gram-negative, mi-croaerophilic bacterium which is usually found in human stomach and it causes gastrointesti-nal diseases such as peptic ulcer, chronic gastritis and stomach cancer. The current estab-lished medical procedures to diagnose the H. pylori infection are endoscopy and biopsy basedtests including bacterial culture and rapid urease test (RUT) which are very painful and notsuitable for routine clinical test. We developed a simple Residual Gas Analyzer based MassSpectroscopy (RGA-MS) technique to detect the biomarkers for the diagnosis of H. pylori in-fection by means of breath analysis. Our study revealed that this infection can be linked withmolecular hydrogen (H 2 ) and 13 C isotopic fractionation of carbon-di-oxide in exhaled hu-man breath (data from more than 150 patients). We exploited the concept of 13 C-Urea breathtest ( 13 C-UBT) measuring different isotopes of carbon-di-oxide (CO 2 ) molecules in ex-haled breath for the detection of the infection. The prototype breath analyzer utilizes a simplemass-spectrometric technique. It measures the 13 CO 2 / 12 CO 2 isotope ratios, expressedas the delta-over-baseline (DOB) value, in exhaled breath samples from patients. This methodoffers selective detection of Peptic Ulcer Disease (PUD), Non- ulcerous Dyspepsia (NUD) asthe complicacies of H. pylori infection by analyzing these potential biomarkers. The diagnos-tic accuracy, precision and validity of the results were also confirmed by high-resolution andhigh-sensitive optical Cavity Ring-Down Spectroscopy (CRDS) measurements. We performedboth endoscopic biopsy-based RUT and 13 C-UBT on more than 150 patients enrolled fromthe eastern region of India. We found that only around 53% of RUT result matched with theoutcomes of 13 C-UBT. We thereafter performed receiver operating characteristic (ROC) curveto evaluate the diagnostic parameters of RUT.

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Results obtained that sensitivity and specificity of 61.5% and 68%, respectively for RUT incomparison to 13 C-UBT (Fig. 1). This result indicates that around 38% H. pylori positivepatients remained unidentified and undiagnosed in RUT. For cross verifications, we performeda second time 13 C-UBT of all the H. pylori positive patients after the 8 weeks of 2 week stan-dard eradication Fig. 1. ROC Plot Fig. 2. Different stages of infection. therapy, which showedeither eradication or reduction in H. pylori activity. Therefore, present study confirmed thediagnostic superiority of 13 C-UBT over RUT.Summary and conclusion (i) Our developed prototype and findings may offer a simple, valid,cost-effective and robust universal strategy which can be used as an alternative non-invasivepoint-of-care (POC) diagnostic mechanism for routine clinical practices as well as for follow-up of patients. (ii) The procedure of RUT leads to false results due to missed sample site orimproper preservation of biopsy samples, whereas the 13 C-UBT provides the global informa-tion of whole stomach and it is very specific to the chemical activity of H. pylori. Hence, 13C-UBT detects the presence of infection more accurately than RUT, thus showing the fallacy inRUT method.Patent: A System and Kit for Non-invasive detection of Peptic Ulcer Disease, Non-UlcerousDyspepsia and Helicobacter Pylori Infection. A Maity and M Pradhan. FILE NO - 201631002214.[2] S Som, A De, G D Banik, A Maity, C Ghosh, M Pal, S B Daschakraborty, S Chaudhuri, SJana and M Pradhan 2015 Mechanisms linking metabolism of Helicobacter pylori to 18O and13C-isotopes of human breath CO2 Sci. Rep. 5 10936 [3] A Maity, M Pal, S Maithani, BGhosh, S Chaudhuri and M Pradhan 2016 Molecular hydrogen in human breath: a new strat-egy for selectively diagnosing peptic ulcer disease, non-ulcerous dyspepsia and Helicobacterpylori infection J. Breath Res. 10(3), 036007

1Department of Gastroenterology, AMRI Hospital, Salt Lake City, JC-16 and 17, Kolkata 700098, India.

P5.09. Selective and Fast Responsive Sensitized Micelle forDetection of Fluoride Level in Drinking Water

Ria Ghosh and Samir Kumar Pal

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Consumption of excess of fluoride ions through the drinking water has adverse side effectson human health. According to statistics, a large number of people suffer from dental and os-teofluorosis worldwide, owing to the consumption of fluoride effected water. Hence, successfulquantification of the level of fluoride ions in drinking water seems to be the call of the hour.For that, we developed a sensor based on an anionic micelle (SDS) - hematoporphyrin complexduly sensitized by Fe (III) chloride. The micelle-hematoporphyrin complex is highly fluorescentwhich is rendered non-fluorescent by the incorporation of Fe (III) ions within the core of thehematoporphyrin molecule. This complex displays strong “turn on” fluorescence upon recog-nition of fluoride (F-) ions in water. We also compared the sensitivity of this hematoporphyrincomplex in different ionic and neutral micellar environments and observed the highest sensitiv-ity in the anionic environment. The microscopic understanding of the processes involved in the“turn on” fluorescence was achieved using density functional theory and molecular simula-tions. In addition, our developed sensor suffers insignificant interference from environmentallyrelevant anions and cations making it an excellent material for detection along with the quan-tification of fluoride ions.

References:(1) Selective and Fast Responsive Sensitized Micelle for Detection of Fluoride Level in Drink-ing Water, ACS Sustainable Chem. Eng. 2019, 7, 1635516363.

P5.10. Analysis and detection of adulteration in cow milk usingNIR Spectroscopic method

Supratim Sen and Soumen Mondal

Amongst the most important food products that we consume are cow milk and olive oil thatsuffers the problem of adulteration in the Indian market. Cow milk are mostly adulterated usingwater to increase the volume but to maintain the other constituents’ urea, sugar, vegetable oil,etc. are also used as adulterant. Here, we have analysed and tried to detect the adulterationpresent in the cow milk using Near-Infrared (NIR) Spectroscopic method. In the absorbancespectrum it was observed that at 2200 nm and 2159 nm a new peak emerges with the addition ofurea in milk and the amplitude of this absorbance peak increases with increase in the amount ofconcentration of urea. Also, it was observed that at 2274 nm with the addition of sugar in milkanother distinct peak emerges and the peak amplitude increases with increase in the amountof sugar concentration. So, on the basis on this study detection of adulterant in milk can bepossible by NIR spectroscopic method.

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P5.11. NaLiK, an Indigenous Device for Rapid, Reliable andSimultaneous Assessment of Sodium, Lithium and Potassiumfor Management of Fluid Balance and Bipolar Disorder in

Human SubjectsDeep Shikha and Samir Kumar Pal

Electrolytes like sodium , potassium , magnesium , calsium etc. are essential in main-taining the fluid balance and homeostasis in human body. They are also useful biomarker inunderstanding patho-physiology of a host of diseases. The major aim of this study is to de-velop a strategy for fast, reliable and simultaneous assessment of sodium (Na+), lithium (Li+)and potassium (K+) in human samples. The device is developed utilizing the basic principle ofoptical emission spectroscopy (OES). The atomic emission spectra of the ions during their tran-sition are acquired and analysed for the simultaneous detection of the specific electrolytes. Anindigenously developed software is used to acquire the optical signal and to calculate the elec-trolyte concentration. The device shows a satisfactory correlation in linear regression analysisfor the three electrolytes (adjusted R2 values 0.954, 0.932 and 0.984 for Na+, Li+ and K+ re-spectively) with respect to standard ISE method. The device utilizes very small amount (≈100L) of serum and provides a good correlation with commercially available costly devices likeBlood Gas Analyser, Ion Selective Electrode for blood electrolyte analysis. The indigenouslydeveloped low cost device has feature to offer simultaneous assessment of the essential elec-trolytes. To our understanding the device would be ideal for the point of care management ofconstantly recurring physiological disorders including Chronic Kidney Diseases (CKD) andBipolar Disorder in economically challenged countries.

References:“NaLiK, a Self-developed Device for Rapid, Reliable and Simultaneous Assessment of Sodium,

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Lithium and Potassium for Management of Fluid Balance and Bipolar Disorder in HumanSubjects”, Journal of Analytical Atomic Spectrometry 34 (2019) 1875.

P5.12. Mil-Q-Way, Estimation of Milk QualityLopamudra Roy, Soumen Mondal and Samir Kumar Pal

The current study utilizes the optical spectroscopic method to assess the quality of milkbased on the colloidal property, i.e. optical density (OD) of the milk at 365 nm (Factor 1) andthe identification of Riboflavin (RF) or Vitamin B2, intrinsically present in all types of milk,by measuring the fluorescence intensity around 520 nm (excitation at 365 nm; Factor 2). Thecombination of these two factors provide a unique identity to the milk from different origins. Aprototype called Mil-Q-Way has been developed to be used in real field for assessing the milkquality. Two-parameter plot (Factor 1 in x-axis and Factor 2 in y-axis) named Mil-Q-Way plotdifferentiates the quality of the milk from different commercial origins. The simple, low costspectroscopy-based devise is shown to screen the presence of harmful adulterants in milk.

P5.13. Spark spectrometry of toxic smokes: towards a portable,inexpensive, and high-resolution environment monitoring

instrumentAnimesh Halder, Soumendra Singh and Samir Kumar Pal

Inductively coupled plasma mass spectrometry and laser-induced breakdown spectroscopyare the most popular techniques for monitoring toxic gases in the environments. Apart fromsensitivity and resolution of the techniques, they suffer from several issues including portabilityand high cost. For design and realization of a low cost, spark spectrometry based portableinstrument for monitoring toxic gases in our environments is the main motive of the presentwork. We have introduced several toxic smokes into a gas chamber containing our developedinstrument. We have also investigated the capability of the instrument for online analysis ofsuspended particulate matter as well as various gaseous elements in the smokes. We have alsodeveloped software for the practical interface. The apparatus has been successfully tested tomonitor several toxic fumes including cigarette smoke and NOx. It has also been demonstratedthat the instrument is equally efficient to monitor air quality in the open environment, for ex-ample, presence of nitrogen, oxygen, and water vapor in the ambient condition. In the presentwork, we have demonstrated some important spectroscopic studies including role of water va-por (solvation) in the ionization of potassium, which is an active ingredient of toxic smokes, in

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the ionization which leading to the generation of atomic emission under the spark spectrometercan also be achieved with our instrument. The sensitivity of the instrument is found to be subppm (0.27 ±0.13 ppm) in the case of cigarette smoke in ambient condition. The simplicity andextremely cost-effective design can provide an alternative method of detection of fumes in airand can serve as a cheap alternative for costly/bulky bench-top instruments.

P5.14. Analysis of δD, δ 18O and δ 17O isotopes of water inhuman gastric fluid and exhaled breath using integrated cavity

output spectroscopySayoni Bhattacharya, Mithun Pal, Abhijit Maity, Sujit Chaudhuri1 and Manik Pradhan

The stable isotopes of water (DD, δ 18O and δD17O) have long been utilized for betterunderstanding the hydrological cycle [1]. Recently, there has been growing interest in waterisotopes analysis for biomedical applications including measurement of total body water andinsulin resistance [2]. In the present study we mainly focused on the analysis of major naturalisotopes of water i.e. O18 and O17 for oxygen, and H2(or Deuterium, D) for hydrogen waterisotopes present in exhaled air vapour and gastric fluid to explore the physiological metabolismof water in human body. An ultrasensitive laser absorption spectrometer based on off-axisintegrated cavity output spectroscopy was exploited here for precise monitoring of the threestable isotopes δD, δ 18O and δ 17O of water both in liquid and vapour form.

Figure 5: Box-Whiskers plot of the variations of water isotopes (δ 18O, δ 17O and δD) in (a)human exhaled breath and (b) human gastric fluid

The δ 18O and δ 17O values in exhaled breath (fig. 1a) have been found to be ranged from-12.22% to -7.65% and from -8.40% to -4.39% respectively, whereas the distribution of δDisotope values spanned from -115.24% to -92.40%. The measurement precisions of each watervapour isotopes δD, δ 18O and δ 17O were found to be 0.20%, 0.05%, and 0.05%, respectivelyat 100 sec. We have also studied the isotopic distribution in human gastric fluid (fig. 1b) and therange of δ 18O, δ 17O and δD values were found to be spanned from -16.22% to -8.73%, from-10.40% to -2.52% and from -137.38% to -111.78% respectively. All data for δ 18O, δ 17O, andδD for liquid sample were measured with precision of 0.03%, 0.03%, and 0.2% respectively.

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We observed that isotope values are markedly depleted for exhaled air in comparison to gastricfluid, which implies that the isotopic fractionations occur between the gastric fluid and exhaledbreath. Our findings will help us for better understanding the isotopic fractionations of waterin human physiology and in the pathogenesis of gastrointestinal diseases (e.g. H. pylori infec-tion and gastric ulcer).

1Department of Gastroenterology, AMRI Hospital, Salt Lake City, JC-16 and 17, Kolkata 700098, India.

References:(1) Nathan Wolf, Seth D. Newsome, Marilyn L. Fogel,Carlos Martinez Del Ri, The Auk 130(2):323330,2013(2) ESF Berman, EL Melanson, T Swibas, SP Snaith and JR Speakman, European Journal ofClinical Nutrition (2015) 69, 1091–1098

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