Entropy of electrolytes

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/100/5/10.1063/1.466365The entropy of 1–1 and 2–2 model electrolytes is calculated from an expansion in terms of the multiparticle correlation functions. For electrolytes, a simple truncation of this expansion is never sufficient for the accurate calculation of the entropy,even in the limit of low concentration, in marked contrast to the behavior for short‐ranged potentials. However, a partial, but infinite‐order, summation of the expansion is shown to yield both the correct low‐concentration limit and excellent results over a wide range of concentrations for both 1–1 and 2–2 electrolytes. The consequences of this result for some earlier applications of the entropy expansion to electrolytes are discussed

The crystal–liquid interface of a body‐centered‐cubic‐forming substance: Computer simulations of the r − 6 potential

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/91/6/10.1063/1.456897.The interfaces between a bcc crystal and its melt are studied by molecular dynamics simulation. Three distinct crystal/melt interfaces, (100), (111), and (110) are studied. For all interfaces the variation with z, the coordinate perpendicular to the interfacial plane, of the single particle density (averaged over the directions perpendicular to z) and the diffusion constant are measured. Although the 10–90 widths of the density peak‐height profiles differ significantly among the three interfaces (6, 9, and 7 molecular diameters, respectively), the corresponding 10–90 widths of the diffusion constant profiles are nearly identical with a common value of about four molecular diameters. This leads to the conclusion that the differences in apparent structural width are due primarily to geometric considerations and not to differences in average local molecular environments

Calculation of the entropy from multiparticle correlation functions

This is the publisher's version, also available electronically from http://journals.aps.org/pra/abstract/10.1103/PhysRevA.45.5680.We consider three approximate expressions for the entropy of a single-particle fluid that require as input only the pair-correlation function g(r). By evaluating numerically these entropy estimates, for several model interparticle interactions of varying range, we examine the accuracy of these expressions compared to the ‘‘exact’’ entropy determined from computer simulation. With the exception of the one-component plasma at very low densities, the entropy of all systems studied can be approximated within 10% of the exact value for fluid densities up to 95% of the freezing density, with the agreement improving for the shorter-ranged potentials. For hard spheres, a preliminary extension to third-order terms is presented

Consistent integral equations for two- and three-body-force models: Application to a model of silicon

This is the publisher's version, also available electronically from http://journals.aps.org/pre/abstract/10.1103/PhysRevE.47.2491.Functional differentiation of systematic expansions for the entropy, in the grand ensemble [B. B. Laird and A. D. J. Haymet, Phys. Rev. A 45, 5680 (1992)], leads directly to consistent integral equations for classical systems interacting via two-body, three-body, and even higher-order forces. This method is both a concise method for organizing existing published results and for deriving previously unpublished, higher-order integral equations. The equations are automatically consistent in the sense that all thermodynamic quantities may be derived from a minimum on an approximate free-energy surface, without the need to introduce weighting functions or numerically determined crossover functions. A number of existing approximate theories are recovered by making additional approximations to the equations. For example, the Kirkwood superposition approximation is shown to arise from a particular approximation to the entropy. The lowest-order theory is then used to obtain integral-equation predictions for the well-known Stillinger-Weber model for silicon, with encouraging results. Further connections are made with increasingly popular density-functional methods in classical statistical mechanics

Density functional theory of freezing for hexagonal symmetry: Comparison with Landau theory

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/88/6/10.1063/1.453839.Density functional theory, studied recently by us [J. Chem. Phys. 8 7, 5449 (1987)] is used to study the freezing of hard disks and hard spheres into crystals with hexagonal symmetry. Two different numerical techniques are used, namely a Gaussian approximation to the crystal density and a more general Fourier expansion of the crystal density. The results from these methods are compared with each other, more approximate versions of density functional theory, and computer simulations. In addition, we compare density functional theory with Landau theories of first order transitions, in which the free energy is expanded as a power series, usually in just one order parameter. We find that traditional Landau theory has little validity when applied to the freezing transition

Translation of the L-species dsRNA genome of the killer-associated virus-like particles of Saccharomyces cerevisiae

Virus-like particles containing the L (P1)-species of double-stranded RNA (dsRNA) were isolated from Saccharomyces cerevisiae, and the translational activity of the virus-like particle-derived dsRNA was analyzed in the wheat germ cell-free system. Denaturation of the dsRNA immediately prior to in vitro translation resulted in the synthesis of one major and at least three minor polypeptides, whereas undenatured dsRNA, as expected, did not stimulate [35S]methionine incorporation into polypeptides, but actually slightly inhibited endogenous activity. The major in vitro translation product of the denatured L-dsRNA was shown to be identical with the major L-dsRNA containing virus-like particle capsid polypeptide on the basis of three criteria: co-electrophoresis on sodium dodecyl sulfate polyacrylamide gels, immunoprecipitation, and tryptic peptide analysis. We have therefore established that the L-dsRNA genome encodes the major virus-like particle capsid polypeptide. This result adds considerable support to the hypothesis that the L-dsRNA genome acts as a helper genome to the smaller (1.6 x 10(6) dalton) M-dsRNA genome in killer strains of yeast by providing the M-dsRNA containing virus-like particles with their major coat protein

Highly metastatic K7M2 cell line: A novel murine model capable of in vivo imaging via luciferase vector transfection

Osteosarcoma is rare and little improvement in survival rates has occurred in the last 25 years despite modern chemotherapeutic treatment. Bioluminescent cell lines for the modeling of osteosarcoma have shown success in tracking metastases in vivo, but commonly use adenoviral vectors to transfect the native cell line with bioluminescent reporters. The purpose of this study was to develop an orthotopic model for metastatic osteosarcoma capable of in vivo monitoring of metastatic and primary tumor burden in an immunocompetent mouse and compare that model to its wild type pathogenesis. K7M2 cells were transfected using a plasmid vector and were stable after 12 weeks. Thirty-four female BALB/c mice aged four to five weeks underwent orthotopic implantation of either wild type (n=12) or transfected (n=22) K7M2 cells in the proximal tibia. Mice were monitored for tumor growth and weekly In Vivo Imaging System (IVIS) imaging was performed to monitor for pulmonary metastasis. Although tumors developed sooner in the wild type group, no significant differences were seen compared to Transfected Group 1 in rate of inoculation, growth rates after first detection, metastatic rate, and time between inoculation and death. This study establishes a new murine model for metastatic osteosarcoma using the K7M2-wt cell line transfected with a non-viral plasmid luciferase vector. The benefits of this preclinical model include an intact immune system and orthotopically driven metastatic disease; this model appears comparable to its wild type counterpart. In the future, the model may be used to examine promising immunomodulatory therapies using bioluminescence in vivo

A 20 Ghz Depolarization Experiment Using the ATS-6 Satellite

A depolarization experiment using the 20 GHz downlink from the ATS-6 satellite was described. The following subjects were covered: (1) an operational summary of the experiment, (2) a description of the equipment used with emphasis on improvements made to the signal processing receiver used with the ATS-5 satellite, (3) data on depolarization and attenuation in one snow storm and two rain storms at 45 deg elevation, (4) data on low angle propagation, (5) conclusions about depolarization on satellite paths, and (6) recommendations for the depolarization portion of the CTS experiment

A depolarization and attenuation experiment using the CTS satellite. Volume 1: Experiment description

An experiment for measuring precipitation attenuation and depolarization on the Communications Technology Satellite (CTS) 11.7 GHz downlink is described. Attenuation and depolarization of the signal received from the spacecraft is monitored on a 24 hour basis. Data is correlated with ground weather conditions. Theoretical models for millimeter wave propagation through rain are refined for maximum agreement with observed data. Techniques are developed for predicting and mimimizing the effects of rain scatter and depolarization on future satellite communication systems