A molecular dynamics test of the Hertz–Knudsenequation for evaporating liquids†
Robert Hołyst,*a Marek Litniewskia and Daniel Jakubczykb
The precise determination of evaporation flux from liquid surfaces gives control over evaporation-driven
self-assembly in soft matter systems. The Hertz–Knudsen (HK) equation is commonly used to predict
evaporation flux. This equation states that the flux is proportional to the difference between the pressure
in the system and the equilibrium pressure for liquid/vapor coexistence. We applied molecular dynamics
(MD) simulations of one component Lennard-Jones (LJ) fluid to test the HK equation for a wide range of
thermodynamic parameters covering more than one order of magnitude in the values of flux. The flux
determined in the simulations was 3.6 times larger than that computed from the HK equation. However,
the flux was constant over time while the pressures in the HK equation exhibited strong fluctuations
during simulations. This observation suggests that the HK equation may not appropriately grasp the
physical mechanism of evaporation. We discuss this issue in the context of momentum flux during
evaporation and mechanical equilibrium in this process. Most probably the process of evaporation is
driven by a tiny difference between the liquid pressure and the gas pressure. This difference is equal to the
momentum flux i.e. momentum carried by the molecules leaving the surface of the liquid during
evaporation. The average velocity in the evaporation flux is very small (two to three orders of magnitude
smaller than the typical velocity of LJ atoms). Therefore the distribution of velocities of LJ atoms does not
deviate from the Maxwell–Boltzmann distribution, even in the interfacial region.
I. Introduction
Evaporation is a ubiquitous process in nature affecting globalwarming and the efficiency of car engines. Controlled evaporationis used to crystallize proteins to elucidate their structures andultimately their functions. The evaporation of solvents in softmatter systems permits the control of self-assembly. A dilutesample of micellar or polymer solution can easily be driven intomore condensed phases by evaporation of the solvent instead ofcumbersome mixing of the highly condensed phase. One can thustrace the whole phase diagram in the search for new phases andstructures. For example, Nie et al.1 demonstrated the efficientincorporation of nanorods into block copolymer cylindricalmicelles by solvent evaporation-driven self-assembly. Merlinet al.2 used a dedicated microfluidic tool based on evaporationto observe the nucleation and growth of charge-stabilized colloidalcrystals. Toolan et al.3 used a spin-coating technique and showedthat the ordering process of colloidal particles depends crucially
on the volatility of the solvent. During fast evaporation onlydisordered aggregates are formed, while slow evaporation leadsto well-ordered structures. Jakubczyk et al.,4 Derkachov et al.5
and Kolwas et al.6 observed various surface (thermodynamic)states and surface phase transitions in a freely evaporatingdroplet of suspension. Niton et al.7 created an artificial motorby driving collective rotations of chiral liquid crystalline moleculesin a monolayer at the water surface. The whole system acted as anano-windmill and was powered by water evaporation. The controlof evaporation flux in this experiment permitted the slowingdown of the rotations to 10�2 Hz, i.e. to a frequency 14 orders ofmagnitude smaller than for the rotation of a single molecule. Allthe experiments related to ordering in soft matter systems viasolvent evaporation show that precise control over evaporationflux is crucial for evaporation-driven self assembly in soft mattersystems.
Evaporation mass flux from the liquid surface is commonlycalculated from the Hertz–Knudsen (HK) equation.7 The HKequation (as derived by Knudsen himself) follows from thekinetic theory of gases via the formula giving the number ofmolecules hitting a surface in gas at equilibrium, per unit areaand unit time. The direct determination of the number density,and above all, true energy/velocity distribution of evaporatingmolecules, is experimentally hardly feasible (compare experi-ments on cold atoms in traps8,9). Thus, out of necessity, the HK
a Institute of Physical Chemistry Polish Academy of Sciences, Kasprzaka 44/52,
01-224, Warsaw, Poland. E-mail: [email protected], [email protected] Institute of Physics of the Polish Academy of Sciences, Al Lotnikow 32-46,
PL-02668, Warsaw, Poland
† Electronic supplementary information (ESI) available: Details of MD simula-tions. See DOI: 10.1039/c5sm01508a
equation must be expressed in terms of intensive thermo-dynamic properties. Pressure and temperature are used insteadof number density and mean velocity, while the mass flux isusually expressed by means of the rate of change of mass ortemperature of the sample. Thus, the testing of the HK equationencounters a convolution of issues: the correct setting of theproblem at a molecular level and the correct transition fromextensive to intensive variables. The test also encompasses thelong-standing problem10 of whether the rate of the process canbe described by a formula devised for an equilibrium state.Experimental results obtained for rarefied gases (low vacuum)are obscured by effects such as back scattering, the formation ofa Knudsen layer, etc. On the other hand, testing the HK equationin a high vacuum practically limits measurements to the propertiesof the sample itself (change of temperature and/or mass) – themeasurement of dynamic pressure and the pseudo-temperatureof escaping vapor seems unfeasible.
The HK equation expressed in intensive thermodynamicvariables relates the mass flux jHK (defined as the number ofparticles evaporating per unit of time from the unit area) to thepressure difference:
where pliq is the pressure of the liquid during evaporation and peq isthe equilibrium pressure of the vapor/liquid coexistence at Tliq – thetemperature of the liquid during evaporation. Verification of theHK equation started with Knudsen himself. He became aware thatthe experimentally observed evaporation flux, jm, was lower thanthat predicted theoretically, jHK, and felt compelled to introduce a(notorious) evaporation coefficient a scaling the flux in eqn (1):
jm = ajHK (2)
Although there is no fundamental need for an evaporationcoefficient a other than 1, the discussion of this issue recurs(just to mention a couple of reviews, spread over severaldecades).11–16 However, it is admitted that the diversity ofresults, in particular those obtained for water11–16 (a in therange from 0.001 to 1), seems to suggest that there may be someadditional barrier for evaporation. However, large variation of acasts doubt on the validity of the HK equation, if judged from thepurely physical point of view. Several decades after Knudsen, theproblem of the evaporation coefficient still persists and oftentesting the HK equation is reduced to simply finding a.
The HK equation is routinely used in thermogravimetry17–19
(TG, TGA). In TG, the mass flux is monitored directly byweighting the sample under controlled temperature conditions.However, many TG experiments use a flow of neutral gas tocarry evaporating molecules away and mimic vacuum evapora-tion. The corresponding evaporation coefficient has a differentphysical meaning than for ordinary evaporation into air. Areview on evaporation of pure metals into a vacuum, mostlyrelying on TG experiments, is given in the paper by Safarianet al.15 The values of evaporation coefficients reported there arebetween 0.8 and 1. Interestingly, computer simulations20 for
argon evaporating into a vacuum gave a = 2 instead of 1. Thecomputer simulations also revealed strong temperature profilesinside the evaporating liquid and thus cast doubts on thecorrect choice of temperature Tliq (eqn (1)) in the experiments.Further experiments of evaporation into a vacuum were per-formed by the Berkeley group.21–23 Their experiments werestraightforward: droplets of water or other polar liquids wereinjected into a high vacuum (o0.07 Pa). The temperature of thedroplets was measured by Raman thermometry (with �2 Kaccuracy) versus the residence time.21–23 Since heat was carriedaway solely by evaporation, the evaporation flux could bedetermined. The mass loss and the temperature distributioninside the droplet were accounted for and the radiative heattransport was negligible. It was also noticed that the tempera-ture dependence of the enthalpy of vaporization and of the heatcapacity reciprocally cancelled out over the entire temperaturerange studied. Fitting the data to the HK equation required atemperature dependent evaporation coefficient. For example,the authors found the evaporation coefficient of water to be0.6 � 0.08 at 258 K. In determining the heat flux, the authorsused a value of enthalpy of vaporization corresponding tothe temperature equilibrium between phases (the values ofenthalpy of vaporization are known along the vapor saturationline). This raises some old concerns, (recognized for example inthe context of supersonic expansion24) since evaporation into avacuum is far from equilibrium in many respects. It can beargued19 that the equilibrium enthalpy of evaporation shouldbe supplemented with the kinetic energy associated with theflux escaping ballistically into the vacuum (compare: stagnationversus static enthalpy). However, it can also be shown that theadditional terms in the enthalpy are below 20% of the wholeenthalpy and can hardly be responsible for the whole discre-pancy of the obtained value of the evaporation coefficient versusthe results of other authors. The Boston College/AerodyneResearch group was able to verify the HK equation at equili-brium.25 In this case, a train of droplets of water was travellingin an atmosphere at full equilibrium with them, which resultedin no overall mass exchange. However, isotopic labelling wasused to count interchanged particles (natural gas/liquid isotopepartitioning was accounted for) and the result was comparedwith the HK equation prediction. The value of the evaporationcoefficient for water obtained by the Boston College/AerodyneResearch25 group in the same temperature range as the Berke-ley group used21–23 (B258 K) was 0.32 � 0.04. Their results arein agreement with those of the IP/IPC PAS group, obtained(indirectly) from the HK equation relatively close to equili-brium.26 The IP/IPC PAS group studied the evaporation ofsingle levitated droplets of water in nearly saturated vapor. Ingeneral, different measurements/computer simulations per-formed by different techniques and groups show27 that theevaporation coefficient a in eqn (2) is between 0.001 and 2. Eventhe most precise experiments21–27 differ by a factor of 2 and thediscrepancy between experiments and computer simulations isalmost one order of magnitude as we show in this paper. Suchhuge differences indicate that eqn (1) and (2) may not correctlygrasp the physical mechanism behind the evaporation process.
The purpose of this paper is to test the HK equation in situationsmore common to evaporation-assisted self assembly i.e. at highvapor pressure. We show that a = 3.6 in this case. Thus thediscrepancy between experiments (Boston group25,28 a = 0.3) andour computer simulations (a = 3.6) is one order of magnitude.We identified two problems in such tests (either experimental orin computer simulations). One of them is the precise determina-tion of the equilibrium pressure. Because evaporation is drivenby very small pressure differences, a small relative error in thisquantity precludes proper verification of the HK equation. Forthis reason, a precise test of eqn (1) and (2) requires very precisedetermination of the phase diagram and the pressures. Thesecond problem is the flow around the evaporating droplet,which changes the mechanical equilibrium and affects the massflux from the evaporating surface. We discuss both issues in ourpaper. The paper is organized as follows: in Section II we definethe system. In Section III we analyze the evaporation of the liquidslab and test the HK equation. Section IV contains our conclusionsand further analysis based on the momentum flux and mechanicalequilibrium established in the system during evaporation.
II. Computer simulations – descriptionof the system
The simulations were performed using the classical moleculardynamic (MD) method. Periodic boundary conditions were appliedin the simulation box. In order to attain the desired level ofaccuracy (see ESI†), Newton equations of motion were solved usingthe Cowell–Numerov 4th order implicit method.29,30 The fluidconsisted of Lennard-Jones (LJ) particles interacted by the potentialtruncated at R = 2.5s in a following way:
jðrÞ ¼e
sr
� �12� s
r
� �6� �þ d for r=s � 2
gr
s� R
� �2Y R� r
s
� �for 2o r=s
8>>><>>>:
(3)
where r is the inter-particle distance, Y is the Heavisidefunction, e and s are the particle energy and size; g and d are theconstants adjusted to make j(r) differentiable in the wholespace. All the numerical values given further on are expressedin reduced LJ units. For argon the values of the units are: length(s = 3.5 � 10�10 m), number density (2.33 � 1028 m�3), mass(m = 40 amu), time (s(m/e)1/2 = 2.3 ps), energy (e = 112kB K =1.5 � 10�21 kg m2 s�2 and e/kB = 112 K sets the temperaturescale), velocity (150 m s�1), momentum (10�23 kg m s�1),pressure (3.6 � 106 kg (m � s2)�1).
The simulated system is shown in Fig. 1. The simulationswere performed using a constant energy and volume method ina box with edges Lx = Ly E 80rliq
�1/3, where rliq is the liquiddensity. Lz/s changed from 704 to 1468 depending on the gasdensity. The total initial number of particles in the liquid statewas always 448 000 and in the gas state varied from 182 016 to359 370. The mass center of the liquid slab was always placed inthe center of the whole system and periodic boundary condi-tions were applied along all axes. We defined the liquid surface
as the xy surface crossing the z axis at z = �zliq, where the localdensity is equal to one-half of its maximum value. The liquidparameters: Tliq, rliq, pliq were determined by averaging over allthe particles placed at least 10s below zliq. Boundary conditionsthat forced evaporation were applied at the ends of the z axis(Fig. 1) by introducing subsystems at z 4 0.5Lz � zh andz o �0.5Lz + zh where zh had a value between 40s and 75sdepending on the gas density and the system size. The temperatureof the subsystem was kept constant (by scaling the velocities) andequal to the heating temperature Theat significantly larger than Tliq.The pressure was controlled by keeping the subsystem (Fig. 1)density lower than the density rheat. The condition was realized byrandomly removing particles from the subsystem. Both velocityscaling and particle removal were performed once every 20 timesteps. The procedure did not change the subsystem momentum –the total momentum of the system was always equal to 0. Theaccuracy of our simulations and the sources of errors are presentedin the ESI.†
All simulation values of the temperature and pressure werecalculated from the standard formulas involving zth compo-nents of velocity and the z component of the pressure tensor:
T ¼
Pnj¼1nzj2
nkB(4)
p ¼ pzz ¼1
V
Xnj¼1
mnzj2 �Xni4 j
zij@j@zij
zij
! !(5)
V is the volume enclosing n particles, vzj is the z-componentof the velocity of j particle, n is the number of particles and zij isthe z-component of the vector joining the center of mass of
Fig. 1 A schematic representation of a simulated system measuring Lx �Ly � Lz. In the middle of the system we place a liquid slab of thickness 2zliq
and temperature Tliq. At the beginning of the simulations the liquid slab is atequilibrium with its vapor at fixed temperature and pressure. The processof evaporation is initiated by heating the vapor far from the slab to atemperature Theat higher than Tliq. The liquid temperature is not fixed, butsettles during the evaporation process.
particles i and j. The equipartition rule held in all the casesconsidered. Due to the small system size, the fluctuations and,as a result, the errors of T and especially of p estimated usingthe z-component of velocity and pressure tensors were significantlylower than those for the calculations using the x or y components.The temperature of the liquid varied between 0.797 and 0.899(Table S1 in the ESI†) and the equilibrium pressure varied between0.014 and 0.032 (with a typical error of 10�5, see Table S1 ESI†).Eqn (4) is valid for temperature determination, because thez-component velocity distribution in the interfacial region andalso in the gas and liquid phase is practically given by theMaxwell–Boltzmann function (ESI†).
III. Results: average mass flux and massflux as a function of time
The difference between the vapor or liquid pressure and thevapor–liquid equilibrium value peq(T) is very small duringevaporation. Therefore the study requires computer simula-tions at a very high level of accuracy. For the LJ vapor liquidequilibrium the literature gives peq(T) with an error of around1�2 � 10�4 in LJ units, which is much too high for our purposeof testing the HK equation. We found sufficiently accuratepeq(T) data (with errors of around 10�5 to 5 � 10�6) byperforming our own vapor–liquid equilibrium simulations fortwo phase systems described by the potential given in eqn (3). Bothequilibrium and non-equilibrium (evaporation) simulations wereperformed for systems of very similar sizes to eliminate the possibleinfluence of a finite system size (the so called size effect) on thedifference between p and peq. The results are given in Table S1(ESI†). The values of the equilibrium pressure obtained in thesimulations (Table S1 in the ESI†) were fitted using the equation31
(Antoine equation) (6):
peqðTÞ ¼ A exp � B
T þ C
� �(6)
with the following values of the parameters: A = 26.6913, B =6.21423, and C = 0.025386. The standard error for the pressurefrom eqn (6), se B 10�5, was estimated on the basis of the datafrom Table S1 (ESI†). In further analysis the vapor–liquidequilibrium pressure peq(T) was calculated from eqn (6). Thenon-equilibrium simulations started from the initial conditionsof the equilibrium between the liquid slab and the vapor (Fig. 1;Table S1, ESI†). We initiated evaporation by heating the gasphase subsystem (Fig. 1) well above zliq to Theat and changed itsdensity to rheat (Table S2 ESI†). The temperature of the sub-system remained equal to Theat during the whole evaporationprocess (Fig. 1). After the strongly non-equilibrium behaviorof the system at the beginning of the evaporation processthe system attained a quasi-stationary regime during whichthe liquid thermodynamic parameters were approximately con-stant. The temperature, density and pressure profiles areshown in Fig. S1 in the ESI.† The system develops a tempera-ture profile in the quasi-stationary regime and evaporates at theexpense of the internal energy of the gas phase – we add the
energy in the subsystem shown in Fig. 1 by keeping its tempera-ture constant at T = Theat. The temperature changes linearly withdistance z from Theat at the border of the simulation box to Tliq atthe surface of the liquid (Fig. S1, ESI†). The temperature isconstant and equal to T = Tliq in the whole liquid slab. The vapordensity changes such that together with the temperaturechanges it ensures a constant pressure in the vapor phase.Finally within the error of the simulations the pressure in theliquid is equal to the pressure of the vapor. We consider thisissue of mechanical equilibrium during evaporation further inthe discussion section. The results of non-equilibrium simula-tions are given in Table S2 in the ESI† and Fig. 2.
The flux was measured directly using eqn (7) in threeregions, each restricted by 2xy surfaces, shifted above zliq byzi and zi+1 where zi/s = 5, 15, 25 and 40 for i = 1. . .4.
jm ¼1
V
Xnj¼1nzj
* +(7)
where the summation is over all n particles enclosed in theconsidered volume V and hi means the time averaging. In thesteady state regime, the results were independent of the studiedregion along the z-axis. According to the generalization to theHertz–Knudsen relation, the flux from liquid to gas duringevaporation is given by eqn (2). The estimation for the evapora-tion coefficient a was found by using the parameters from TableS2 (ESI†) in the minimization of
W2 ¼
jm
a� jHK
� �2
se jHKð Þ2(8)
From this procedure we obtain a = 3.6 � 0.4. se( jHK) in (8),which estimates the standard error.
The fluxes presented in Fig. 2 were averaged over timeduring the whole evaporation process in a quasi-stationaryregime. No dependence of the ratio jHK/jm on jm can be seen.However for small jm the errors are very high. This is an
Fig. 2 The ratio jHK/jm (filled circles) as a function of jm. The error bars arese( jHK)/jm (Table S2, ESI†). The dashed line and the grey band represent a�1
and its error respectively. The data are from Table S2 in the ESI.†
important argument for the validity of the estimation for asince any non-physical effect, if present, should influence thepressure difference in eqn (1) relatively much more strongly forsmall jHK than for larger values. In Fig. 3 we show the flux as afunction of time together with the HK flux predicted fromeqn (1). Interestingly, although jm is nearly constant duringthe simulations, the pressure difference (in the HK equationeqn (1)) strongly fluctuates and the time-scale of fluctuations isvery large. This sort of behavior was characteristic of all non-equilibrium simulations from Table S2 and Fig. S2 in the ESI.†
IV. Conclusions and new hypothesisconcerning evaporation
Fig. 3 gives direct proof that mass flux from the surface of a liquid isnot directly driven by the difference between the liquid pressure andthe equilibrium pressure. The mass flux divided by the evaporationcoefficient a�1jm (eqn (5)) is constant and equal to around 4 � 10�5
after reaching the stationary state (at times larger than 16 000 units).But, the flux, jHK, determined from the pressure difference fluctuatesbetween 8 � 10�5 and 2 � 10�5. Such large changes of jHK andalmost constant flux, jm, suggest that the mechanism of evaporationis not appropriately grasped by the HK equation (eqn (1)). In allstudied cases (for various thermodynamic conditions) we observedvery large fluctuations of jHK and a nearly constant flux, jm (ESI†).Here we will put forward a hypothesis as to the possible mechanismof evaporation and notorious problems in experimental/computersimulation tests of the HK equation.
In our previous publication20 we observed that a liquid slabevaporating into a vacuum is characterized by the followingequation:
pliq = jp (9)
where pliq is the pressure inside the liquid slab and jp is themomentum flux from the surface. The momentum carried byparticles leaving the surface of the liquid compensates thepressure inside the liquid. Thus the evaporation process is likeshooting a cannon, where the shell and the cannon jointly keepthe momentum equal to 0 in the shot. The momentum flux isgiven by
jp ¼1
2mrevu
2 (10)
where rev is the number density in the evaporating flux, m isthe mass of the molecule and u is the average velocity in thisflux. The mass flux is given by
jm = mrevu (11)
From eqn (10) and (11) we find that the relation between theliquid pressure and the mass flux is
jm ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi2mrevpliq
p(12)
or
jm ¼ffiffiffiffiffiffiffiffiffiffiffiffiffi2mpliq
u
r(13)
We think that this equation may be generalized to other casesi.e. evaporation into vapor of non-zero pressure i.e.
pliq � pvap = jp (14)
where the difference between liquid and vapor pressures duringevaporation is exactly matched by the momentum flux from thesurface of the evaporating liquid. Eqn (14) has a natural limit ofevaporation into a vacuum (pvap = 0), given by eqn (9), whichhas been verified in many simulations.20,32 Unfortunately, athigh vapor pressure, studied in this paper, this equation isextremely hard to test because all the pressure differences,evaporation density and velocity u are very small. For example,in our simulations the largest evaporation flux jm = 3.2 � 10�4
LJ units, where one LJ flux unit is 3.5 � 1030 (m2 s)�1. Becausethe typical density in this case is between rev = 0.01 and 0.04and the velocity is between u = 0.008 and 0.032, we find that themomentum flux and the pressure difference in eqn (14) are inthe order of 10�5 to 10�6 in LJ units. These momentum fluxesare comparable or even smaller than the errors in the pressuredetermination. The smallest mass fluxes determined in oursimulations (B10�5) and typical velocities for this flux are ofthe order of 10�3 i.e. 0.15 m s�1. Thus the pressure difference ineqn (14) is 10�8 in this case, whereas the accuracy in thedetermination of the pressure is 10�5 (three orders of magni-tude larger). In experiments the tests are even harder, becausethe experimental fluxes are orders of magnitude smaller thanthe ones obtained in our simulations. In our units they arebetween 10�7 and 10�11. For example, for a water dropletevaporating down to 0.8 mm in radius, in air at atmosphericpressure at 286.8 K and B0.97 relative humidity, the flux doesnot exceed 1.4 � 1023 (m2 s)�1 which is 104 times smaller thanin the presented simulation. For a similar droplet of diethyleneglycol evaporating in dry nitrogen (a void of glycol vapor) at
Fig. 3 Fluxes jHK (empty squares) and a�1jm (black circles) as a function oftime for simulation under the following thermodynamic conditions (pliq =0.02273, Tliq = 0.85323, rheat = 0.0115, Theat = 2.0). Each point is averagedover a time interval of 6580 LJ units length during which around 17 000particles evaporated from both sides of the liquid slab. The liquid surfaceparameter zliq decreased during the interval by around 1.5s. The first twopoints are obtained in the initial non-stationary stage.
298 K the flux is a further 100 times smaller i.e. 1021 (m2 s)�1.Such small fluxes correspond to very small mean velocities, u,much smaller than cm s�1. This means that if an evaporatingdroplet of micrometer size moves at even a small velocity (evenmm s�1) its momentum is sufficient to modify the momentumflux during evaporation and therefore to significantly changethe mass flux. May be this is the main reason for the largedivergence of evaporation coefficients found in experimentsand computer simulations. In most experiments the vapormoves with respect to the evaporating liquid surface and there-fore affects the mechanical equilibrium set by eqn (14), chan-ging the mass flux accordingly. The analysis of the averagevelocity in the flux suggests that for practical reasons theMaxwell–Boltzmann distribution is valid for the z-componentof the velocity as illustrated in the ESI† (Fig. S4).
Summarizing: our results suggest (Fig. 3) that the Hertz–Knudsen equation does not correctly describe the evaporationprocess. We put forward a hypothesis that evaporation is drivenby tiny differences between pressure in the evaporating liquidphase and pressure in the vapor phase. The momentum flux ofevaporating molecules/atoms should exactly balance this differenceduring evaporation. We further hypothesize that the density rev inthe evaporation flux is probably equal to the density of vapor atequilibrium with a liquid at temperature Tliq. More careful experi-ments at reduced pressure of the vapor at rest or under controlledflow conditions are needed to investigate this problem further.Computer simulations performed under vacuum conditions are agood starting point for such investigations.20,32
Finally, the self-assembly process via controlled evaporationis currently a very promising method to build large scalehierarchical structures in soft matter systems.33–36 New meth-ods for controlling this process based on pressure variationsand flow can emerge from our theoretical study, especiallywhen combined with novel sophisticated experiments37 per-formed in evaporating systems.
Acknowledgements
This work was supported by the National Science Center,Poland, under grant number 2014/13/B/ST3/04414.
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