Richard Elliott
Mercer University, School of Medicine, Faculty Member
- Mercer University, College of Pharmacy and Health Sciences, Faculty Memberadd
- Richard Laurence Elliott, MD, PhD, FAPA Dr. Elliott is professor and Director of Medical Ethics and Professionalism,... moreRichard Laurence Elliott, MD, PhD, FAPA
Dr. Elliott is professor and Director of Medical Ethics and Professionalism, Mercer University School of Medicine, and Adjunct Professor of Law, Mercer University School of Law. He was born in California, and received his MD, MS (Theoretical Chemistry), and PhD (Biophysics) at the University of Wisconsin. He completed residency training in psychiatry at the University of Wisconsin, and completed fellowships in consultation liaison psychiatry and forensic psychiatry at Rush Presbyterian St. Lukes in Chicago. He is certified by the American Board of Psychiatry and Neurology, American Board of Forensic Psychiatry, the American Medical Society for Alcoholism and Other Drug Dependencies, and has added qualifications in geriatric psychiatry and forensic psychiatry. Prior to coming to Mercer in 1994, he was Medical Director for Georgia's Department of Mental Health, Mental retardation, and Substance Abuse, and a surveyor for JCAHO. He has published over 100 articles (not including abstracts) and has made over 100 national and state wide presentations. He has received five national awards for public service to the mentally ill, and
was named Georgia Psychiatrist of the Year by the National Alliance for the Mentally Ill Georgia. He received teaching awards at the Medical College of Georgia, the Medical College of Virginia, and Mercer University School of Medicine. In 1996 he received the first Stern Family Fund award of $100,00, described by NPR as a "MacArthur prize for the public sector." In 2004 he received the Mercer University School of Medicine Humanism in Medicine award.
He has served as an expert witness in a number of cases, including Olmstead, Cason v Seckinger (rights of the mentally in prisons), and as a surveyor of the quality of mental health services in Georgia.
He has two children Robert Matthew and Kathryn Rose, enjoys cycling, and is an avid but mediocre tennis player.edit
Recent years have seen a push to apply criminal law to HIV exposure and transmission, often driven by the wish to respond to concerns about the ongoing rapid spread of HIV in many countries. Particularly in Africa, some groups have begun... more
Recent years have seen a push to apply criminal law to HIV exposure and transmission, often driven by the wish to respond to concerns about the ongoing rapid spread of HIV in many countries. Particularly in Africa, some groups have begun to advocate for criminalization in response to the serious phenomenon of women being infected with HIV through sexual violence or by partners who do not reveal their HIV diagnoses to them. While these issues must be urgently addressed, a closer analysis of the complex issues raised by criminalization of HIV exposure or transmission reveals that criminalization is unlikely to prevent new infections or reduce women's vulnerability to HIV. In fact, it may harm women rather than assist them, and have a negative impact on public health and human rights. This paper is a slightly revised version of a document originally released in December 2008 by a coalition of HIV, women's and human rights organizations. It provides ten reasons why criminalizing HIV exposure or transmission is generally an unjust and ineffective public policy. The obvious exception involves cases where individuals purposely or maliciously transmit HIV with the intent to harm others. In these rare cases, existing criminal laws – rather than new, HIV-specific laws – can and should be used.Ces dernières années, l’application du droit pénal à l’exposition au VIH ou à sa transmission a été préconisée, souvent pour répondre aux préoccupations suscitées par la propagation continue du VIH dans beaucoup de pays. En particulier en Afrique, certains groupes ont commencé à demander la criminalisation pour répondre au grave phénomène des femmes infectées par le VIH suite à des violences sexuelles ou par des partenaires leur ayant caché leur séropositivité. S’il faut aborder de toute urgence ces problèmes, une analyse plus approfondie des questions complexes soulevées par la criminalisation de l’exposition au VIH ou de sa transmission révèle que cette mesure a peu de chances de prévenir de nouvelles infections ou réduire la vulnérabilité des femmes au VIH. En fait, elle risque plutôt de faire du tort aux femmes et de nuire à la santé publique et aux droits de la personne. Cet article est une version légèrement révisée d’un document publié en décembre 2008 par une coalition d’organisations s’occupant du VIH, des droits de la personne et du statut de la femme. Il donne dix raisons pour lesquelles la criminalisation de l’exposition au VIH ou de sa transmission est généralement une politique publique injuste et inefficace. L’exception évidente concerne la transmission intentionnelle du VIH ou dans le dessein de porter préjudice. Dans ces rares cas, le droit pénal existant, plutôt que de nouvelles lois spécifiques au VIH, peut et doit être utilisé.En los últimos años se ha visto más presión por aplicar el derecho penal a la exposición y transmisión del VIH, por lo general motivada por el deseo de responder a las inquietudes respecto a la continua y rápida transmisión del VIH en muchos países. Particularmente en África, algunos grupos han empezado a abogar por la penalización en respuesta al grave fenómeno de mujeres infectada con VIH mediante violencia sexual o por parejas que no les revelan su diagnóstico de VIH. Aunque se debe tratar estos problemas urgentemente, un análisis más detenido de los aspectos complejos que surgen de la penalización de la exposición o transmisión del VIH, revela que es improbable que la penalización impida nuevas infecciones o reduzca la vulnerabilidad de las mujeres al VIH. Es más, podría perjudicar a las mujeres en vez de ayudarlas, y tener un impacto negativo en la salud pública y los derechos humanos. Este artículo es una versión algo modificada de un documento publicado originalmente en diciembre de 2008 por una coalición de organizaciones de VIH, mujeres y derechos humanos. Expone diez razones por las que la penalización de la exposición o transmisión del VIH generalmente es una política pública injusta e ineficaz. La excepción obvia es los casos en que las personas transmiten VIH deliberada o maliciosamente con la intención de perjudicar a los demás. En estos casos raros, se puede y se debe usar las leyes penales vigentes, en vez de nuevas leyes específicas al VIH.
Research Interests: Criminal Law, Communication, Human Rights, Trust, Social Problems, and 16 moreStigma, Sexual Violence, Prejudice, Health, Public Health, HIV/AIDS policy, Humans, Human right, Reproductive health, Sex Education, Female, Risk factors, Hiv Aids, Public health systems and services research, Risk Factors, and Public Policy
Using recently developed techniques for locating phase transitions, we study the effects of fluctuations in a field theoretic model on block copolymer behavior. Specifically, we couple the use of complex Langevin dynamics within a field... more
Using recently developed techniques for locating phase transitions, we study the effects of fluctuations in a field theoretic model on block copolymer behavior. Specifically, we couple the use of complex Langevin dynamics within a field theoretic framework and thermodynamic integration techniques for the calculation of free energies of fluctuating systems to show a revised prediction of the diblock copolymer phase diagram. Further, these methods are extended into blend systems to investigate unbinding transitions and critical micelle concentrations in cylindrical phases.
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Polymeric mixtures of hydrocarbons, alcohols have been simulated with discontinuous potential models to characterize the Helmholtz energy of the repulsive reference fluids (A0) along with the first and second order perturbation... more
Polymeric mixtures of hydrocarbons, alcohols have been simulated with discontinuous potential models to characterize the Helmholtz energy of the repulsive reference fluids (A0) along with the first and second order perturbation contributions (A1, A2) as functions of density and composition. Taken together, these terms generate a complete equation of state for the mixture, including temperature effects as well as density and composition. The specific hydrocarbons studied were methane, ethane, propane, n-butane, n-hexane, n-heptane, n-decane, and benzene. The specific alcohols were water, methanol, ethanol, n-propanol, and n-octanol. Unfortunately, a slight inconsistency was encountered when the trend observed for these small molecules was extrapolated to the long chain limit. Therefore, we extend the analysis to mixtures of n-alkanes, branched hydrocarbons, and aromatics with polymeric molecules of: n-alkanes, ethyl-styrenes, ethyl-propylenes, and isoprenes. The perturbation contributions can be accurately characterized by van der Waals mixing rules and compared with the MCSL SAFT and Guggenheim-Staverman theories.
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An emergent viral pathogen termed severe fever with thrombocytopenia syndrome virus (SFTSV) is responsible for thousands of clinical cases and associated fatalities in China, Japan, and South Korea. Akin to other phleboviruses, SFTSV... more
An emergent viral pathogen termed severe fever with thrombocytopenia syndrome virus (SFTSV) is responsible for thousands of clinical cases and associated fatalities in China, Japan, and South Korea. Akin to other phleboviruses, SFTSV relies on a viral glycoprotein, Gc, to catalyze the merger of endosomal host and viral membranes during cell entry. Here, we describe the postfusion structure of SFTSV Gc, revealing that the molecular transformations the phleboviral Gc undergoes upon host cell entry are conserved with otherwise unrelated alpha- and flaviviruses. By comparison of SFTSV Gc with that of the prefusion structure of the related Rift Valley fever virus, we show that these changes involve refolding of the protein into a trimeric state. Reverse genetics and rescue of site-directed histidine mutants enabled localization of histidines likely to be important for triggering this pH-dependent process. These data provide structural and functional evidence that the mechanism of phlebov...
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The M genome segment of Bunyamwera virus (BUNV)-the prototype of both the Bunyaviridae family and the Orthobunyavirus genus-encodes the glycoprotein precursor (GPC) that is proteolytically cleaved to yield two viral structural... more
The M genome segment of Bunyamwera virus (BUNV)-the prototype of both the Bunyaviridae family and the Orthobunyavirus genus-encodes the glycoprotein precursor (GPC) that is proteolytically cleaved to yield two viral structural glycoproteins, Gn and Gc, and a nonstructural protein, NSm. The cleavage mechanism of orthobunyavirus GPCs and the host proteases involved have not been clarified. In this study, we investigated the processing of BUNV GPC and found that both NSm and Gc proteins were cleaved at their own internal signal peptides (SPs), in which NSm domain I functions as SP(NSm) and NSm domain V as SP(Gc) Moreover, the domain I was further processed by a host intramembrane-cleaving protease, signal peptide peptidase, and is required for cell fusion activities. Meanwhile, the NSm domain V (SP(Gc)) remains integral to NSm, rendering the NSm topology as a two-membrane-spanning integral membrane protein. We defined the cleavage sites and boundaries between the processed proteins as ...
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ABSTRACT Discontinuous molecular dynamics is combined with thermodynamic perturbation theory to provide an efficient basis for characterising molecular interactions based on vapour pressure and liquid density data. Several prospective... more
ABSTRACT Discontinuous molecular dynamics is combined with thermodynamic perturbation theory to provide an efficient basis for characterising molecular interactions based on vapour pressure and liquid density data. Several prospective potential models are discretised to permit treatment by Barker–Henderson perturbation theory. The potentials are characterised by 11 wells ranging over radial distances from the site diameter to three times that diameter. Considered potential models include the Lennard-Jones (LJ), square-well, Yukawa (Yuk) and multi-line potentials, and their combinations. The optimal model is found to be a combination of square-well and Yuk potentials, with the switch position and Yuk decay set to universal values. This model provides average vapour pressure deviations of less than 10% for a database of 86 aliphatic, aromatic and naphthenic compounds. The LJ potential provides the least competitive accuracy. Considering statistical information criteria facilitates the identification of the optimal model.
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ABSTRACT NVT molecular dynamics simulations have been used to investigate the effects of attractive forces on the structure and thermodynamics of n-pentane in solution with spheres at various concentrations from 66·7% to 6·25% mole... more
ABSTRACT NVT molecular dynamics simulations have been used to investigate the effects of attractive forces on the structure and thermodynamics of n-pentane in solution with spheres at various concentrations from 66·7% to 6·25% mole fraction of pentane and density of 0·4426 g cm-3 and temperature of 430 K. Simulations were performed using first the repulsive part of the potential as formulated by Weeks, Chandler, and Anderson (WCA potential) and then the full Lennard-Jones potential. The bond lengths for the n-pentane were constrained to be 0·153 nm, while the bond angles were allowed to vary slightly from the equilibrium angle of 109·7° by a realistic potential. The LJ potential parameters were σLJ = 0·3923 nm and ϵ/κ = 72 K for both the n-pentane sites and spheres. The effect of attractive forces on the fluid structure was pronounced and most significant at low concentrations of n-pentane. The chains clustered among themselves while cavitating the spheres at high concentrations of n-pentane, indicating microscopic separation of the two components. The chain-sphere correlation was suppressed at high concentrations of n-pentane and increased as the solution became dilute in n-pentane. This behaviour is compared with solute-solvent and solute-solute clustering of dilute solution of spheres in spheres, and spheres in diatomics near the critical point of the solvent.
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ABSTRACT NVT molecular dynamics simulations have been used to investigate the effects of attractive forces on the structure and thermodynamics of n-pentane in solution with spheres at various concentrations from 66·7% to 6·25% mole... more
ABSTRACT NVT molecular dynamics simulations have been used to investigate the effects of attractive forces on the structure and thermodynamics of n-pentane in solution with spheres at various concentrations from 66·7% to 6·25% mole fraction of pentane and density of 0·4426 g cm-3 and temperature of 430 K. Simulations were performed using first the repulsive part of the potential as formulated by Weeks, Chandler, and Anderson (WCA potential) and then the full Lennard-Jones potential. The bond lengths for the n-pentane were constrained to be 0·153 nm, while the bond angles were allowed to vary slightly from the equilibrium angle of 109·7° by a realistic potential. The LJ potential parameters were σLJ = 0·3923 nm and ϵ/κ = 72 K for both the n-pentane sites and spheres. The effect of attractive forces on the fluid structure was pronounced and most significant at low concentrations of n-pentane. The chains clustered among themselves while cavitating the spheres at high concentrations of n-pentane, indicating microscopic separation of the two components. The chain-sphere correlation was suppressed at high concentrations of n-pentane and increased as the solution became dilute in n-pentane. This behaviour is compared with solute-solvent and solute-solute clustering of dilute solution of spheres in spheres, and spheres in diatomics near the critical point of the solvent.
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... of Mixtures J. Richard Elliott, Jr. ... An extensive compilation of critical properties which included these types of mixtures was published by Hicks and Young (1975). A second source which provided data for a few systems not listed... more
... of Mixtures J. Richard Elliott, Jr. ... An extensive compilation of critical properties which included these types of mixtures was published by Hicks and Young (1975). A second source which provided data for a few systems not listed in Hicks and Young (1975) was due to Kay (1972). ...
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The Bunyaviridae is one of the largest families of viruses, containing more than 300 named isolates. The viruses are characterized by a tripartite, single-stranded RNA genome that encode their gene products using a negative-sense or... more
The Bunyaviridae is one of the largest families of viruses, containing more than 300 named isolates. The viruses are characterized by a tripartite, single-stranded RNA genome that encode their gene products using a negative-sense or ambisense strategy. The family is classified into five genera: Orthobunyavirus, Hantavirus, Nairovirus, Phlebovirus, and Tospovirus. Most of these viruses (except hantaviruses) are transmitted by arthropod vectors, and many are associated with diseases in humans, domesticated animals, or plants. The interaction between virus and vector is discussed. The virion RNAs and proteins of viruses in different genera are schematically summarized and the bunyavirus replication cycle is described. Finally, the importance of reverse genetics to the study of these viruses is emphasized.
ABSTRACT An effective combination of Discontinuous Molecular Dynamics (DMD) and second order Thermodynamic perturbation Theory (TPT) can be employed to simulate the entire Equation of State (EOS) of pure components and also to offer a... more
ABSTRACT An effective combination of Discontinuous Molecular Dynamics (DMD) and second order Thermodynamic perturbation Theory (TPT) can be employed to simulate the entire Equation of State (EOS) of pure components and also to offer a rigorous procedure to evaluate the perturbation contributions of any SAFT-like EOS. Based on DMD/TPT methodology, Elliott and Gray (The Journal of Chemical Physics, 123, 184902, 2005) proposed a correlation for n-alkanes viable at high packing fractions. Recently, Ghobadi and Elliott (Fluid Phase Equilibria, article in press, 2011) extended the application of this correlation to low density limit including the critical point region. The improved correlation, named as SPEAD11, is used to study the effect of chain length on the critical properties of n-alkanes. Classically, it has been known for several years that at long chain limit, critical temperature and compressibility factor lean to a finite number while critical pressure and density tends to zero. But, the non-classical behavior at the long chain limit has remained as a mystery. To tackle this problem, White’s renormalization group theory is applied on SPEAD11 to calculate the critical properties as well as vapor pressure and binodal of pure n-alkanes. It is demonstrated that although the White’s method offers a physical and efficient tool to obtain the non-classical behavior of small molecules in the critical point vicinity, it would not be valid as the number of carbons exceeds 30. The binodal shape gets too flat in the critical region and the uncertainty of the predicted critical density becomes substantially large. These observations are partly attributed to the numerical nature of White’s method and the critical solver. Some corrections are suggested to improve these deficiencies and to broaden the applicability of White’s method to C60H122. By taking these results into consideration, a reasonable estimation for the critical properties and scaling trends of n-alkanes at the long chain limit are presented and compared to corresponding predictions available in the literature.
In this work, a new classical density functional theory is developed for group-contribution equations of state (EOS). Details of implementation are demonstrated for the recently-developed SAFT-γ WCA EOS and selective applications are... more
In this work, a new classical density functional theory is developed for group-contribution equations of state (EOS). Details of implementation are demonstrated for the recently-developed SAFT-γ WCA EOS and selective applications are studied for confined fluids and vapor-liquid interfaces. The acronym WCA (Weeks-Chandler-Andersen) refers to the characterization of the reference part of the third-order thermodynamic perturbation theory applied in formulating the EOS. SAFT-γ refers to the particular form of "statistical associating fluid theory" that is applied to the fused-sphere, heteronuclear, united-atom molecular models of interest. For the monomer term, the modified fundamental measure theory is extended to WCA-spheres. A new chain functional is also introduced for fused and soft heteronuclear chains. The attractive interactions are taken into account by considering the structure of the fluid, thus elevating the theory beyond the mean field approximation. The fluctuations of energy are also included via a non-local third-order perturbation theory. The theory includes resolution of the density profiles of individual groups such as CH2 and CH3 and satisfies stoichiometric constraints for the density profiles. New molecular simulations are conducted to demonstrate the accuracy of each Helmholtz free energy contribution in reproducing the microstructure of inhomogeneous systems at the united-atom level of coarse graining. At each stage, comparisons are made to assess where the present theory stands relative to the current state of the art for studying inhomogeneous fluids. Overall, it is shown that the characteristic features of real molecular fluids are captured both qualitatively and quantitatively. For example, the average pore density deviates ∼2% from simulation data for attractive pentadecane in a 2-nm slit pore. Another example is the surface tension of ethane/heptane mixture, which deviates ∼1% from simulation data while the theory reproduces the excess accumulation of ethane at the interface.
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Optimal binary interaction coefficients have been determined for a generalized equation of state for associating mixtures using a large data base of 170 binary systems compiles from the literature. The data base covers gases (Hâ, Nâ, CO,... more
Optimal binary interaction coefficients have been determined for a generalized equation of state for associating mixtures using a large data base of 170 binary systems compiles from the literature. The data base covers gases (Hâ, Nâ, CO, COâ, and HâS), hydrocarbons, alcohols, and water. Results show substantial improvements in accuracy for the equation of state presented here relative to the Soave equation. Average errors in estimated bubble point pressure ranged from 2.1% to 8.7% for CHâ, HâS, Nâ, CO, COâ, Hâ, HâO, MeOH, and EtOH systems when optimal binary interaction coefficients were used. The accuracy for the gaseous components is roughly equivalent to that of the Soave equation, but for water, methanol, and ethanol systems, the optimized Soave equation provides 20%, 15%, and 10% error. For systems without optimal binary interaction coefficients, predictive methods were developed. For predictions treating nongaseous components, errors in estimated bubble point pressure ranged from 0.7% to 8.1% when this method was applied. For predictions treating gaseous components, errors in estimated bubble point pressure ranged from 5.0% to 37.6% for CHâ, HâS, Nâ, CO, COâ, and Hâ when the predicted interaction coefficients were applied. Tables of optimal binary interaction coefficients where available and estimated interaction coefficients where necessary are presented for roughly 350 binary systems over a wide range of temperatures and pressure.
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Sensitivity to the interferon-induced protein, MxA, has previously been demonstrated for viruses belonging to the Orthobunyavirus, Hantavirus and Phlebovirus genera of the Bunyaviridae family. We have extended these findings to a member... more
Sensitivity to the interferon-induced protein, MxA, has previously been demonstrated for viruses belonging to the Orthobunyavirus, Hantavirus and Phlebovirus genera of the Bunyaviridae family. We have extended these findings to a member of the fourth and remaining genus containing viruses that infect man and other animals, the nairovirus Dugbe virus (DUGV). Indirect immunofluorescence experiments using VA9 cells (Vero cells permanently transfected with MxA cDNA) revealed strongly reduced DUGV antigen expression, suggesting that MxA inhibited DUGV replication. Western and Northern blot analyses showed significantly lower DUGV nucleocapsid (N) protein expression and DUGV genomic RNA, respectively, in the presence of MxA. Viral titres were also reduced by more than two orders of magnitude in VA9 cells compared with control VN36 cells. This finding may have application to nairovirus therapeutics.
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ABSTRACT Binary and multicomponent vapor-liquid equilibria of synthesis gas components (H2, CO, CH4, and CO2), methanol and water with tetraethylene glycol dimethyl ether (tetraglyme) were studied experimentally at temperatures (473–513... more
ABSTRACT Binary and multicomponent vapor-liquid equilibria of synthesis gas components (H2, CO, CH4, and CO2), methanol and water with tetraethylene glycol dimethyl ether (tetraglyme) were studied experimentally at temperatures (473–513 K) and pressures (5.3–10.4 MPa) typical of the conventional vapor phase methanol synthesis. Both vapor and liquid phases were sampled directly and analyzed by gas chromatography. Solubilities were expressed in terms of equilibrium K values. Optimal binary interaction coefficients for all components with tetraglyme were obtained for the Soave-Redlich-Kwong equation of state (SRKEOS [1] by minimizing the error in bubble point pressure prediction. K values predicted by the SRKEOS were in good agreement with those obtained experimentally.
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In December 2002, in its ongoing efforts to secure access to affordable HIV/AIDS treatment for all South Africans, the grassroots organization Treatment Action Campaign (TAC) initiated two new proceedings over governmental failure to act... more
In December 2002, in its ongoing efforts to secure access to affordable HIV/AIDS treatment for all South Africans, the grassroots organization Treatment Action Campaign (TAC) initiated two new proceedings over governmental failure to act to prevent mother-to-child transmission of HIV. In March 2003, it launched a national civil disobedience campaign to pressure government into implementing a national treatment and prevention plan, including taking measures to ensure access to affordable medicines.
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ABSTRACT This exploratory study examines Chinese consumers’ perceptions of authenticity. Extended interviews reveal that Chinese consumers do not evaluate products based on a perceived binary relationship between authentic and inauthentic... more
ABSTRACT This exploratory study examines Chinese consumers’ perceptions of authenticity. Extended interviews reveal that Chinese consumers do not evaluate products based on a perceived binary relationship between authentic and inauthentic products. The results suggest, instead, Chinese consumers view authenticity evaluation as relational and hierarchical rather than original and unique. Two additional authenticity types emerge—domesticated and mimicked. The findings help marketing practitioners create new consumer segments based on the authenticity levels of product offerings and simultaneously help preserve brand equity and long-term relationships with consumers.
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Discontinuous molecular dynamics simulations and thermodynamic perturbation theory have been used to study thermodynamic properties for chain molecules. A multistep potential model is considered in this work through characterization of... more
Discontinuous molecular dynamics simulations and thermodynamic perturbation theory have been used to study thermodynamic properties for chain molecules. A multistep potential model is considered in this work through characterization of the vapor pressure and saturated liquid density for the n-alkanes from ethane to octane. The multistep potential model provides ˜4% accuracy for the entire molecular weight range. By contrast, previous studies of the square-well potential showed that the range of the square-well needed to vary with molecular weight to provide comparable accuracy. Therefore, having multiple steps with different depths for each functional group appears to be an essential part of making the potential model transferable. The depths of the wells vary such that the CH2 potential appears flatter than the CH3 potential, in an apparent attempt to moderate the overlaps implicit in the interaction site model.
Research Interests: Engineering, Thermodynamics, Chemical Physics, Vapor Pressure, Physical sciences, and 11 moreCHEMICAL SCIENCES, Heat Capacity, Functional Group, Molecular weight, Thermal Properties, Thermal Expansion, Critical Point, Molecular Dynamic Simulation, Thermodynamic Properties, Equation of State, and Perturbation Theory
Molecular-dynamics simulations are used to investigate the effects of attractive forces on the structure of two chain molecular fluids: n-butane and n-pentane. Simulations are performed using the complete site-site Lennard-Jones potential... more
Molecular-dynamics simulations are used to investigate the effects of attractive forces on the structure of two chain molecular fluids: n-butane and n-pentane. Simulations are performed using the complete site-site Lennard-Jones potential at state points identical with those in previous simulations that used just the repulsive part of the potential. The bond angles are constrained at 109·47° and the bond lengths at 0·153 nm. The potential parameters are σLJ = 0·3923 nm and the ɛ/k = 72 K. Five densities are simulated for butane and four for pentane, all at a constant temperature of 430 K. Comparisons of pressures and the average site distribution functions from simulations for both potential models show an increased effect of attractive forces at low density, very similar to atomic fluids. The magnitude of the attractive-force effect appears to be much greater for chains than for atomic fluids, however, and the magnitude increases with increasing chain length. The simulation results are briefly compared with an approximate RISM theory, but the theory appears to be less accurate for attractive-force than for repulsive effects.
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Results of NVT molecular-dynamics simulations are reported for modelled n-butane and n-pentane over a range of densities at temperatures of about 430 K. The model potential is the repulsive part of the Lennard-Jones potential with bond... more
Results of NVT molecular-dynamics simulations are reported for modelled n-butane and n-pentane over a range of densities at temperatures of about 430 K. The model potential is the repulsive part of the Lennard-Jones potential with bond angles constrained at 109·47° and bond lengths of 0·153 nm, where σ = 0·3923 nm and ɛ/k = 72 K. Simulation results for average site-site distribution functions are compared with results of an approximate RISM theory. Similarly to the case of diatomic fluids, the accuracy of the approximate theory is only qualitative, but trends of key features of the fluid structure are well represented. The softness of the Lennard-Jones potential appears to play a significant role in smoothing away several potential sources of error in the approximate theory.
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In the development of quantitative structure-activity relationships (QSAR), a small subset of chemical compounds must be chosen for synthesis from a much larger population of potentially bioactive molecules. The ultimate goal of the QSAR... more
In the development of quantitative structure-activity relationships (QSAR), a small subset of chemical compounds must be chosen for synthesis from a much larger population of potentially bioactive molecules. The ultimate goal of the QSAR study is to determine, at the lowest cost, the most biologically active member of the population. Hence it is important that the sample be optimally selected for both predictive ability and ease of synthesis. This article describes a method, based on information theory, that simultaneously incorporates these concerns into the substituent selection process. This procedure is essentially a generalization of previous algorithms for obtaining a D-optimal design by examining prediction variances (Mitchell 1974). Results from applying this difficulty-information approach suggest that the method is capable of achieving large decreases in total synthesis difficulty at the expense of only a moderate decrease in predictive ability.
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ABSTRACT An effective combination of Discontinuous Molecular Dynamics (DMD) simulation and second order Thermodynamic Perturbation Theory (TPT) can be employed to simulate the entire phase diagram and also to offer a rigorous procedure... more
ABSTRACT An effective combination of Discontinuous Molecular Dynamics (DMD) simulation and second order Thermodynamic Perturbation Theory (TPT) can be employed to simulate the entire phase diagram and also to offer a rigorous procedure for evaluating the perturbation contributions of any SAFT-like equation of state (EOS). In DMD/TPT methodology, the athermal reference fluid is fused hard sphere chain and is simulated by DMD at one single temperature and several densities. The size of each site type (σ) is adjusted to reproduce experimental liquid density. Then, after the simulation, the first and second order attractive contributions of Helmholtz free energy can be isolated and rigorously computed in accordance with the Barker–Henderson (BH) formalism. To do so, Elliott and co-workers optimized and evaluated a site-base transferable step potential with four wells for more than 500 compounds comprising 30 different families. Parameters of interaction potential (εi, i = 1,4) were adjusted to reproduce experimental saturated liquid density and vapor pressure. Following this procedure, Elliott and Gray {Journal of Chemical Physics, 123 (2005), p. 184902} proposed SAFT-like correlations to the results of simulation known as Step Potential for Equilibria And Dynamics (SPEAD). Ghobadi and Elliott {Fluid Phase Equilibria, v. 306 i.1 (2011) p. 57} recently improved the correlation for the critical point region. The main difference between SPEAD and SAFT-family approaches is the nature of evaluating perturbation contributions. In SAFT formalism, a segment-base continuous interaction potential is considered and adjustable parameters are fitted to the experimental data while SPEAD benefits from site-base discontinuous interactions and raw simulation results. Although site-base approach offers transferability and physical consistency, a segment-base interaction potential becomes absolutely beneficial where Renormalization Group (RG) theory or Density Functional Theory (DFT) is applied on the classical Equation of State (EOS). In this work, a segment-base Lennard-Jones (LJ) interaction potential is developed by re-evaluating the perturbation contributions of SPEAD. The Mean Field and local density approximations are implemented to calculate first and second order perturbation terms, respectively. The first order term is computed using an average radial distribution function at an effective packing fraction. The relation between density and effective packing fraction introduces two adjustable parameters for each component. These parameters along with the minimum of the LJ potential (ε) are fitted to the BH-generated perturbation contributions of SPEAD. The number of segments (m) is regressed to the results of DMD simulation of the reference fluid. Therefore, each component is characterized by 5 parameters: σ, m, ε, c1 and c2. Using the segment-based potential described above and SPEAD+DFT EOS (named as iSPEAD), liquid-vapor density profile and surface tension of several pure components from n-alkanes, branched alkanes, alcohols, acids, ester and so forth were calculated. It should be noted that hydrogen bonding contribution is considered by Wertheim theory. The results show satisfactory agreement with available experimental data. Also, adsorption isotherms of various mixtures were studied by iSPEAD. It is demonstrated that adsorption at the liquid-vapor interface happens when there is a noticeable difference between parameters of constituent components of the mixtures. The final aim of this work is to investigate the potential of DFT to indicate the effect of different experimentally-examined surfactant molecules on the interfacial properties. When dealing with large molecules such as amphiphiles, individual segment densities contain valuable information about the microstructure of the fluid. In such cases, a three-fluid model will be used to obtain the density profiles for hydrophilic head, hydrophobic tail and tail-end segments. The three-fluid model isolates the influence of each part on interfacial properties and provides more in-depth information such as average end-to-end distance of surfactants, surface area per surfactant, aggregation number and so forth.
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A simple and rapid procedure for determining the genotypes of viruses has been applied to analysis of genome subunit reassortment in heterologous crosses of Batai virus, Bunyamwera virus, and Maguari virus, three members of the Bunyamwera... more
A simple and rapid procedure for determining the genotypes of viruses has been applied to analysis of genome subunit reassortment in heterologous crosses of Batai virus, Bunyamwera virus, and Maguari virus, three members of the Bunyamwera serogroup of bunyaviruses. The procedure for determining genotype made use of specific molecular probes to identify the parental origin of the L and M RNA subunits. Complementary DNA copies of the three RNA segments of Bunyamwera virus were prepared by reverse transcription using synthetic oligonucleotide primers for first and second strand synthesis. The cDNA transcripts were inserted into a pBR322 vector and gene-specific probes prepared from nick-translated plasmid DNA. L and M gene-specific probes were identified which could unequivocally discriminate Bunyamwera virus genome subunits in a dot-hybridization test using cytoplasmic RNA extracts immobilised on nitrocellulose filters. None of the S gene-specific probes were sufficiently discriminatory for use in this test. Instead the parental origin of the S RNA subunit was inferred from the electrophoretic mobility of the virion N protein. It was observed that reassortment did not occur at random in heterologous crosses of is mutants of the three viruses, and only the M RNA subunit appeared to segregate freely. However, unrestricted reassortment was observed when recombinant viruses with nonhomologous subunit combinations were used as the parental viruses. It was concluded, therefore, that restriction was mediated at the gene product level and that nonrandom reassortment was not due to incompatibility of genome subunits.
Research Interests:
Oropouche virus (OROV) is a midge-borne human pathogen with a geographic distribution in South America. OROV was first isolated in 1955 and since then is known to cause recurring outbreaks of a dengue-like illness in the Amazonian regions... more
Oropouche virus (OROV) is a midge-borne human pathogen with a geographic distribution in South America. OROV was first isolated in 1955 and since then is known to cause recurring outbreaks of a dengue-like illness in the Amazonian regions of Brazil. OROV however, remains amongst one of the poorly understood emerging viral zoonosis. Here we describe the successful rescue of infectious OROV entirely from cDNA copies of its genome and generation of OROV mutant viruses lacking either the NSm or the NSs coding regions. Characterisation of the recombinant viruses carried out in vitro demonstrated that the NSs protein of OROV is an IFN antagonist as in other NSs-encoding bunyaviruses. Additionally, we demonstrate the importance of the nine C-terminal amino acids of OROV NSs in IFN antagonistic activity. OROV was also found to be sensitive to IFN-α when cells were pre-treated, however the virus was still capable of replicating at doses as high as 10,000 U/ml of IFN-α in contrast to the fami...