@article {2198, title = {Inhibition of solute crystallisation in aqueous H+-NH4+-SO42{\textendash}H2O droplets}, journal = {Physical Chemistry Chemical Physics}, volume = {10}, number = {22}, year = {2008}, note = {ISI Document Delivery No.: 304MXTimes Cited: 7Cited Reference Count: 68Murray, Benjamin J. Bertram, Allan K.}, pages = {3287-3301}, type = {Article}, abstract = {Ice clouds in the Earth{\textquoteright}s upper troposphere can form via homogeneous nucleation of ice in aqueous droplets. In this study we investigate the crystallisation, or lack of crystallisation, of the solute phase and ice in aqueous (NH4)(3)H(SO4)(2)/H2O and NH4HSO4/H2O droplets. This is done using in situ X-ray diffraction of emulsified solution droplets mounted on a cold stage. From the diffraction patterns we are able to identify the phases of crystalline solute and ice that form after homogeneous freezing in micrometer sized droplets. An important finding from this study is that crystallisation of the solute does not always occur, even when crystallisation is strongly thermodynamically favoured. The nucleation and growth of solute phase crystals becomes inhibited since the viscosity of the aqueous brine most likely increases dramatically as the brine concentration increases and temperature decreases. If ice nucleates below a threshold freezing temperature, the brine appears to rapidly become so viscous that solute crystallisation is inhibited. This threshold temperature is 192 K and 180 K, in ( NH4) 3H( SO4) 2 and NH4HSO4, respectively. We also speculate that the formation of cubic ice within a highly viscous brine blocks the solvent mediated cubic to hexagonal phase transformation, thus stabilising the metastable cubic ice in the most concentrated solution droplets.}, keywords = {CUBIC ICE, GLASS-TRANSITION, H2SO4/NH3/H2O AEROSOL-PARTICLES, HOMOGENEOUS ICE NUCLEATION, LIQUID WATER, LOW-TEMPERATURES, NH4HSO4, PHASE-TRANSITIONS, solutions, SULFURIC-ACID, SUPERCOOLED WATER}, isbn = {1463-9076}, url = {://000256114700013}, author = {Murray, B. J. and Bertram, A. K.} } @article {2117, title = {Lipid-specific binding of the calcium-dependent antibiotic daptomycin leads to changes in lipid polymorphism of model membranes}, journal = {Chemistry and Physics of Lipids}, volume = {154}, number = {2}, year = {2008}, note = {ISI Document Delivery No.: 336MXTimes Cited: 8Cited Reference Count: 41Jung, David Powers, Jon Paul Straus, Suzana K. Hancock, Robert E. W.}, month = {Aug}, pages = {120-128}, type = {Article}, abstract = {Daptomycin is a cyclic anionic lipopeptide with an antibiotic activity that is completely dependent on the presence of calcium (as Ca2+). In a previous study [Jung et al., 2004. Chem. Biol. 11, 949-957], it was concluded that daptomycin underwent two Ca2+-dependent structural transitions, whereby the first transition was solely dependent on Ca2+, while the second transition was dependent on both Ca2+ and the presence of negatively charged lipids that allowed daptomycin to insert into and perturb bilayer membranes with acidic character. Differences in the interaction of daptomycin with acidic and neutral membranes were further investigated by spectroscopic means. The lack of quenching of intrinsic fluorescence by the water-soluble quencher, KI, confirmed the insertion of the daptomycin Trp residue into the membrane bilayer, while the kynurenine residue was inaccessible even in an aqueous environment. Differential scanning calorimetry (DSC) indicated that the binding of daptomycin to neutral bilayers occurred through a combination of electrostatic and hydrophobic interactions, while the binding of daptomycin to Mayers containing acidic lipids primarily involved electrostatic interactions. The binding of daptomycin to acidic membranes led to the induction of non-lamellar lipid phases and membrane fusion. (C) 2008 Elsevier Ireland Ltd. All rights reserved.}, keywords = {ANTIMICROBIAL PEPTIDES, Daptomycin, DSC, FLUORESCENCE, lipopeptide, LY146032, membrane fusion, MIMETIC SYSTEMS, MODEL MEMBRANES, P-31 NMR, PHASE-TRANSITIONS, PHOSPHOLIPIDS, RESONANCE ENERGY-TRANSFER, STAPHYLOCOCCUS-AUREUS, X-RAY-DIFFRACTION}, isbn = {0009-3084}, url = {://000258369200006}, author = {Jung, D. and Powers, J. P. and Straus, S. K. and Hancock, R. E. W.} } @article {1516, title = {Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: Crystallization relative humidities and nucleation rates}, journal = {Journal of Physical Chemistry A}, volume = {110}, number = {28}, year = {2006}, note = {ISI Document Delivery No.: 063EXTimes Cited: 12Cited Reference Count: 70Pant, Atul Parsons, Matthew T. Bertram, Allan K.}, month = {Jul}, pages = {8701-8709}, type = {Article}, abstract = {Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10\%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 ( the relative humidity at which 50\% of the droplets crystallize) ranges from about 41 to 51\% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 mu m. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 Am diameter) free of solid material is approximately 34.3\% RH under atmospheric conditions.}, keywords = {AEROSOL-PARTICLES, ATMOSPHERIC AEROSOL, deliquescence, HETEROGENEOUS NUCLEATION, HYGROSCOPIC GROWTH, MINERAL DUST, ORGANIC-COMPOUNDS, PHASE-TRANSITIONS, TROPOSPHERIC AEROSOLS, WATER-UPTAKE}, isbn = {1089-5639}, url = {://000239001600013}, author = {Pant, A. and Parsons, M. T. and Bertram, A. K.} } @article {1519, title = {Crystallization of aqueous inorganic-malonic acid particles: Nucleation rates, dependence on size, and dependence on the ammonium-to-sulfate}, journal = {Journal of Physical Chemistry A}, volume = {110}, number = {26}, year = {2006}, note = {ISI Document Delivery No.: 058DRTimes Cited: 16Cited Reference Count: 63}, month = {Jul}, pages = {8108-8115}, type = {Article}, abstract = {Using an electrodynamic balance, we determined the relative humidity ( RH) at which aqueous inorganic-malonic acid particles crystallized, with ammonium sulfate ((NH4)(2)SO4), letovicite ((NH4)(3)H(SO4)(2)), or ammonium bisulfate (NH4HSO4) as the inorganic component. The results for (NH4)(2)SO4-malonic acid particles and (NH4)(3)H(SO4)(2)-malonic acid particles show that malonic acid decreases the crystallization RH of the inorganic particles by less than 7\% RH when the dry malonic acid mole fraction is less than 0.25. At a dry malonic acid mole fraction of about 0.5, the presence of malonic acid can decrease the crystallization RH of the inorganic particles by up to 35\% RH. For the NH4HSO4-malonic acid particles, the presence of malonic acid does not significantly modify the crystallization RH of the inorganic particles for the entire range of dry malonic acid mole fractions studied; in all cases, either the particles did not crystallize or the crystallization RH was close to 0\% RH. Size dependent measurements show that the crystallization RH of aqueous (NH4)(2)SO4 particles is not a strong function of particle volume. However, for aqueous (NH4)(2)SO4-malonic acid particles ( with dry malonic acid mole fraction) 0.36), the crystallization RH is a stronger function of particle volume, with the crystallization RH decreasing by 6 +/- 3\% RH when the particle volume decreases by an order of magnitude. To our knowledge, these are the first size dependent measurements of the crystallization RH of atmospherically relevant inorganic-organic particles. These results suggest that for certain organic mole fractions the particle size and observation time need to be considered when extrapolating laboratory crystallization results to atmospheric scenarios. For aqueous (NH4)(2)SO4 particles, the homogeneous nucleation rate data are a strong function of RH, but for aqueous (NH4)(2)SO4-malonic acid particles (with dry organic mole fraction = 0.36), the rates are not as dependent on RH. The homogeneous nucleation rates for aqueous (NH4)(2)SO4 particles were parametrized using classical nucleation theory, and from this analysis we determined that the interfacial surface tension between the crystalline ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is between 0.053 and 0.070 J m(-2).}, keywords = {AEROSOL-PARTICLES, ATMOSPHERIC PARTICLES, BALANCE, ELECTRODYNAMIC, HETEROGENEOUS NUCLEATION, HYGROSCOPIC PROPERTIES, MIXTURES, ORGANIC-COMPOUNDS, PHASE-TRANSITIONS, RELATIVE-HUMIDITY, WATER-UPTAKE}, isbn = {1089-5639}, url = {://000238645600017}, author = {Parsons, M. T. and Riffell, J. L. and Bertram, A. K.} } @article {1218, title = {The formation of cubic ice under conditions relevant to Earth{\textquoteright}s atmosphere}, journal = {Nature}, volume = {434}, number = {7030}, year = {2005}, note = {ISI Document Delivery No.: 904JUTimes Cited: 61Cited Reference Count: 30}, month = {Mar}, pages = {202-205}, type = {Article}, abstract = {An important mechanism for ice cloud formation in the Earth{\textquoteright}s atmosphere is homogeneous nucleation of ice in aqueous droplets, and this process is generally assumed to produce hexagonal ice(1,2). However, there are some reports that the metastable crystalline phase of ice, cubic ice, may form in the Earth{\textquoteright}s atmosphere(3-5). Here we present laboratory experiments demonstrating that cubic ice forms when micrometre-sized droplets of pure water and aqueous solutions freeze homogeneously at cooling rates approaching those found in the atmosphere. We find that the formation of cubic ice is dominant when droplets freeze at temperatures below 190 K, which is in the temperature range relevant for polar stratospheric clouds and clouds in the tropical tropopause region. These results, together with heat transfer calculations, suggest that cubic ice will form in the Earth{\textquoteright}s atmosphere. If there were a significant fraction of cubic ice in some cold clouds this could increase their water vapour pressure, and modify their microphysics and ice particle size distributions(5). Under specific conditions this may lead to enhanced dehydration of the tropopause region(5).}, keywords = {CHEMISTRY, CLOUDS, crystallization, HALO, LIQUID WATER, MICROPHYSICS, NUCLEATION, PHASE-TRANSITIONS, X-RAY-DIFFRACTION}, isbn = {0028-0836}, url = {://000227494500041}, author = {Murray, B. J. and Knopf, D. A. and Bertram, A. K.} } @article {956, title = {Deliquescence and crystallization of ammonium sulfate particles internally mixed with water-soluble organic compounds}, journal = {Journal of Physical Chemistry A}, volume = {108}, number = {52}, year = {2004}, note = {ISI Document Delivery No.: 882FPTimes Cited: 38Cited Reference Count: 66}, month = {Dec}, pages = {11600-11608}, type = {Article}, abstract = {The deliquescence and crystallization of ammonium sulfate particles internally mixed with water-soluble organic material have been studied, restricted to an organic mass fraction of less than 0.6. The organic species used were malonic acid, glycerol, levoglucosan (1,6-anhydro-beta-D-glucopyranose), and Suwannee River fulvic acid. Our deliquescence results for systems with malonic acid and fulvic acid are in agreement with existing literature values. Glycerol deliquescence results are slightly lower than previous measurements. The levoglucosan results are the first of this kind. Total deliquescence relative humidities for the different systems are the same within the uncertainty of the measurements when the organic mole fraction is less than approximately 0.35. At an organic mole fraction of 0.6, the maximum deviation of total deliquescence relative humidities between the systems is approximately 10\% relative humidity. We show that thermodynamic calculations based on a simplified version of a model recently proposed by Clegg et al. (J. Aerosol Sci. 2001, 32, 713)1 are in agreement with measured values of deliquescence relative humidity up to an organic mole fraction of approximately 0.4 for most of the systems studied. The crystallization relative humidity (CRH) of mixed systems of ammonium sulfate with malonic acid, glycerol, or levoglucosan decreases significantly from the CRH of pure ammonium sulfate when the organic mole fraction is greater than about 0.25. This is in contrast to our previous study with glutaric acid where CRH remained close to CRH of pure ammonium sulfate up to a glutaric acid mole fraction of 0.4. CRH values are shown to vary depending on the type of,organic present. In terms of atmospheric implications, we estimate that organics, on average, are only a minor perturbation on the deliquescence relative humidity of the pure inorganic particles, whereas the organics, on average, may decrease the CRH of pure inorganic particles significantly and this effect depends on the type of organic material.}, keywords = {ATMOSPHERIC AEROSOL, BLACK CARBON, DICARBOXYLIC-ACIDS, FINE AEROSOL, HUMIC-LIKE SUBSTANCES, HYGROSCOPIC PROPERTIES, MODEL, PHASE-TRANSITIONS, PHYSICAL, RELATIVE-HUMIDITY, STATE}, isbn = {1089-5639}, url = {://000225924800016}, author = {Parsons, M. T. and Knopf, D. A. and Bertram, A. K.} } @article {957, title = {Deliquescence of malonic, succinic, glutaric, and adipic acid particles}, journal = {Journal of Geophysical Research-Atmospheres}, volume = {109}, number = {D6}, year = {2004}, note = {ISI Document Delivery No.: 809FPTimes Cited: 32Cited Reference Count: 46}, month = {Mar}, pages = {8}, type = {Article}, abstract = {In order to understand and predict the role of organic particles in the atmosphere their deliquescence behavior must be understood. Using an optical microscope coupled to a flow cell, we investigated the deliquescence of malonic, succinic, glutaric, and adipic acid particles with sizes ranging from 2 to 40 mm. Deliquescence relative humidities were determined for temperatures ranging from 293 to 243 K. Over this temperature range both succinic acid and adipic acid deliquesced at approximately 100\% relative humidity, whereas malonic acid and glutaric acid deliquesced at significantly lower relative humidities. These results are generally in good agreement with previous studies and are within 3\% of calculations based on the UNIQUAC (universal quasi-chemical) Functional Group Activity Coefficients (UNIFAC) model and recently published interaction parameters. Our studies also include measurements at temperatures below the eutectic temperatures. At these temperatures, ice did not nucleate; rather the particles underwent deliquescence to form metastable solution droplets. This indicates that solid dicarboxylic acids are not good ice nuclei above 243 K and hence will probably not play a role in ice cloud formation at these temperatures.}, keywords = {AEROSOL, AEROSOL PHASE, AMAZON BASIN, AMMONIUM-SULFATE, atmospheric chemistry, ATMOSPHERIC PARTICLES, CIRRUS CLOUD FORMATION, deliquescence, dicarboxylic acid, DICARBOXYLIC-ACIDS, HYGROSCOPIC GROWTH, ice, NUCLEATION, optical microscopy, PHASE-TRANSITIONS, STRATOSPHERIC TEMPERATURES, WATER}, isbn = {0148-0227}, url = {://000220622900002}, author = {Parsons, M. T. and Mak, J. and Lipetz, S. R. and Bertram, A. K.} } @article {704, title = {Surfactant-stabilized structures in confined liquids}, journal = {Journal of Chemical Physics}, volume = {119}, number = {16}, year = {2003}, note = {ISI Document Delivery No.: 731BWTimes Cited: 5Cited Reference Count: 48}, month = {Oct}, pages = {8676-8685}, type = {Article}, abstract = {Grand canonical Monte Carlo simulations are used to investigate the effect of surfactant on binary Lennard-Jones mixtures confined between planar, chemically patterned surfaces. Near bulk demixing coexistence, confined binary mixtures form liquid "bridges" joining specifically patterned surface areas. The length of these bridges is restricted by the unfavorable liquid-liquid interfacial tension, and in the present paper we show that this constraint can be significantly reduced by adding surfactant to the system. This leads to very extended liquid bridges and to other structures not found in the simple two-component case. We give a qualitative discussion of the surface-surfactant -induced liquid structures and examine in detail the associated forces acting between the plates. (C) 2003 American Institute of Physics.}, keywords = {CAPILLARY CONDENSATION, DENSITY-FUNCTIONAL METHOD, HYDROPHILIC SURFACES, HYDROPHOBIC SURFACES, INTERACTION FORCES, LAMELLAR PHASES, LENNARD-JONES FLUID, MORPHOLOGICAL WETTING TRANSITIONS, PHASE-TRANSITIONS, SLIT-LIKE PORES}, isbn = {0021-9606}, url = {://000185865500048}, author = {Overduin, S. D. and Patey, G. N.} } @article {445, title = {Molecular dynamics simulations of a ferroelectric nematic liquid under shear flow}, journal = {Journal of Chemical Physics}, volume = {117}, number = {18}, year = {2002}, note = {ISI Document Delivery No.: 610YYTimes Cited: 5Cited Reference Count: 47}, month = {Nov}, pages = {8551-8564}, type = {Article}, abstract = {We perform nonequilibrium molecular dynamics simulations to examine the change in orientational order of a ferroelectric nematic liquid crystal under shear flow, specifically planar Couette flow. The orientational order is found to decrease with increasing shear rate. This drop in orientational order is not due to structural changes but is rather a result of the director dynamics being flow unstable. Employing both nonequilibrium and equilibrium molecular dynamics with the director orientation fixed, we determine the shear and twist viscosities which relate the pressure tensor to the shear or strain rate tensor in a nematic liquid crystal under flow. The Miesowicz viscosities are then obtained from linear combinations of the shear and twist viscosities. The short-range spatial structure of the ferroelectric nematic liquid crystal is similar to that of a ferroelectric tetragonal I lattice. The relative magnitudes of the Miesowicz viscosities can be understood by examining the shear stress response of this lattice to a shear deformation. (C) 2002 American Institute of Physics.}, keywords = {BOUNDARY-CONDITIONS, COMPUTER-SIMULATION, CRYSTALS, FLUIDS, MONTE-CARLO, PHASE-TRANSITIONS, rheology, STATE, VISCOSITY}, isbn = {0021-9606}, url = {://000178990700045}, author = {McWhirter, J. L. and Patey, G. N.} } @article {5203, title = {Adsorption of DOPC onto Hg from the G|S interface and from a liposomal suspension}, journal = {Journal of Electroanalytical Chemistry}, volume = {516}, number = {1-2}, year = {2001}, note = {ISI Document Delivery No.: 507LLTimes Cited: 21Cited Reference Count: 53}, month = {Dec}, pages = {73-82}, type = {Article}, abstract = {The adsorption of various physical forms of dioleoyl phosphatidylcholine (DOPC) onto a Hg electrode have been studied. The three systems investigated were adsorption of DOPC from the monolayer state present on the gas \ solution (G \ S) interface, the adsorption of 100 nm DOPC liposomes present in the electrolyte, and a mixed system consisting of the co-adsorption of the monolayer and liposomes. The adsorption was characterized by capacitance measurements, chronoamperometry and impedance spectroscopy. The adsorbed layer produced by liposome adsorption was distinctly different as compared to the layer adsorbed from the G \ S interface, whereas the co-adsorbed layer retained most of the liposome layer qualities. A low capacitance region, centered at - 0.40 V (SCE) with values of 1.85, and 1.45 muF cm(-2) for the G \ S and the liposome system were, respectively observed. This region was stable with respect to very negative potential cycling only for the liposome systems. Three phase transitions (denoted by pseudo-capacitance peaks) were noted for the three systems under study; two corresponding to a change in the adsorbed state, and one corresponding to the adsorption-desorption process. The kinetics of these changes were quite different and depended on the nature of the adsorbing species. The most significant differences were observed when measuring the capacity over a large range of perturbation frequency. At low frequencies, desorption of the DOPC layer was observed at very negative potentials for all the systems studied. As the perturbation frequency was increased, the capacitance measured for the G \ S system maintained this characteristic, but surprisingly this was not the case for the liposome systems. In both cases (liposome and co-adsorbed) the capacity, calculated assuming a series RC circuit, was found to be significantly lower than the capacity measured for the Hg \ 0.1 M KCl interface. Preliminary impedance spectra are presented illustrating the non-ideal behavior of the liposomal system. This phenomenon is undergoing further study. A possible mechanism for the adsorption of DOPC from the liposomal state is also presented. (C) 2001 Elsevier Science B.V. All rights reserved.}, keywords = {AGGREGATION PROCESSES, CAPACITANCE, CYTOCHROME-C-OXIDASE, ELECTRIFIED INTERFACES, GRAMICIDIN CHANNEL FUNCTION, INDUCED, lipid monolayer, liposome adsorption, mercury, MERCURY-ELECTROLYTE INTERFACE, phase change kinetics, PHASE-TRANSITIONS, PHOSPHOLIPID MONOLAYERS, SODIUM DODECYL-SULFATE, STRUCTURAL-CHANGES, SUPPORTED LIPID BILAYERS}, isbn = {0022-0728}, url = {://000173029900010}, author = {Stauffer, V. and Stoodley, R. and Agak, J. O. and Bizzotto, D.} } @article {5028, title = {Coexistence and criticality of fluids with long-range potentials}, journal = {Journal of Chemical Physics}, volume = {114}, number = {1}, year = {2001}, note = {ISI Document Delivery No.: 388LUTimes Cited: 35Cited Reference Count: 44}, month = {Jan}, pages = {399-408}, type = {Article}, abstract = {Using mixed-field finite-size scaling simulations, we have investigated the liquid-vapor critical behavior of three-dimensional fluids;vith algebraically decaying attractive pair interactions, which vary like -1/r(3+sigma) with sigma = 3, 1, and 0.1. The finite-size scaling analysis was carried out by matching the critical ordering operator distribution, p(L)(x), against the limiting Ising form, i.e., Ising criticality was assumed. When the potential is short-ranged (sigma = 3) the simulation results are entirely consistent with the expected Ising critical behavior. When the potential is long-ranged (sigma = 1, 0.1), however, marked deviations from Ising behavior are observed, particularly in the form of the critical ordering operator distribution, and in the estimated values of beta/nu. The results are consistent with non-Ising criticality which is predicted theoretically in fluid with long-range interactions. Some results from Gibbs ensemble simulations are also provided in order to sketch the shape of the liquid-vapor coexistence envelope. We discuss the relevance of our results to the current issue of criticality in ionic fluids. (C) 2001 American Institute of Physics.}, keywords = {CRITICAL EXPONENTS, CRITICAL-BEHAVIOR, CRITICAL-POINT, CURVE DIAMETER, GIBBS ENSEMBLE, IONIC BINARY MIXTURE, LENNARD-JONES FLUID, MONTE-CARLO, PHASE-TRANSITIONS, RESTRICTED PRIMITIVE MODEL}, isbn = {0021-9606}, url = {://000166182900046}, author = {Camp, P. J. and Patey, G. N.} } @article {4848, title = {Crystallization of dipolar spheres: A discussion of second-order density functional theory}, journal = {Journal of Chemical Physics}, volume = {112}, number = {24}, year = {2000}, note = {ISI Document Delivery No.: 324HYTimes Cited: 6Cited Reference Count: 43}, month = {Jun}, pages = {10949-10956}, type = {Article}, abstract = {We investigate the application of second-order density functional theory to the crystallization of dipolar hard and soft spheres. It is shown that the results are highly sensitive to the repulsive part of the pair potential, and to the symmetry of the fluid phase considered in the density functional theory. In general, the theoretical results for dipolar soft spheres (with r(-12) repulsion) are found to be physically more reasonable than those obtained for dipolar hard spheres. In particular, the fluid-solid density gap is greatly reduced and lies in the range expected on physical grounds and from simulations. However, theories constructed by expanding about the isotropic fluid phase overestimate the stability of the ferroelectric solid for both models, and fail to predict the stable ferroelectric fluids found in computer simulations. We have carried out calculations using ferroelectric dipolar fluids with both perfect and fluctuating orientational order as "starting points" in the density functional expansion. The results demonstrate the high sensitivity of the theory to the underlying fluid state, and strongly indicate the existence of stable ferroelectric fluids in accord with computer simulations. (C) 2000 American Institute of Physics. [S0021-9606(00)50924-6].}, keywords = {FLUIDS, HARD-SPHERES, INTEGRAL-EQUATIONS, LIQUID-VAPOR INTERFACE, NEMATIC PHASE, orientational order, PHASE-TRANSITIONS, SOFT SPHERES, SOLID-PHASES, STABILITY}, isbn = {0021-9606}, url = {://000087617300033}, author = {Klapp, S. H. L. and Patey, G. N.} } @article {4849, title = {Integral equation theory for dipolar hard sphere fluids with fluctuating orientational order}, journal = {Journal of Chemical Physics}, volume = {112}, number = {8}, year = {2000}, note = {ISI Document Delivery No.: 284RDTimes Cited: 21Cited Reference Count: 53}, month = {Feb}, pages = {3832-3844}, type = {Article}, abstract = {We present an integral equation approach to the structural and thermodynamic properties of a fluid of partially aligned dipolar hard spheres. To relate the two-particle correlation functions to the anisotropic singlet density, we mainly employ the Lovett-Mou-Buff-Wertheim equation. We show that, as in the isotropic case, the mean-spherical approximation and the reference hypernetted chain (RHNC) closures lead to quite different results. This is particularly true at high coupling strengths, where the RHNC theory shows a transition from an isotropic to a ferroelectric fluid phase. The predicted transition temperatures are very close to those one obtains from the RHNC theory for the isotropic fluid. (C) 2000 American Institute of Physics. [S0021-9606(00)50707-7].}, keywords = {BOUNDARY-CONDITIONS, COMPUTER-SIMULATION, DENSITY-FUNCTIONAL THEORY, EXTERNAL MAGNETIC-FIELD, HEISENBERG SPIN FLUID, HYPERNETTED-CHAIN APPROXIMATION, LIQUID-VAPOR INTERFACE, NONSPHERICAL PARTICLES, PARALLEL SPHEROCYLINDERS, PERIODIC, PHASE-TRANSITIONS}, isbn = {0021-9606}, url = {://000085345300041}, author = {Klapp, S. H. L. and Patey, G. N.} }