Multicomponent mixture of charged hard-sphere chain molecules in the polymer mean-spherical approximation

The analytical solution of the recently proposed ideal chain polymer mean-spherical approximation (Yu.Kalyuzhnyi, Mol.Phys., 94, 735(1998)) is presented for the multicomponent mixture of charged hard-sphere linear chain flexible molecules. The solution apply to any mixture of chain molecules with arbitrary distribution of the charge and size of the beads along the molecular backbone. Closed form analytical expressions for the internal energy, Helmholtz free energy, chemical potentials and pressure are derived. By way of illustration thermodynamical properties of several versions of the fluid of charged chain molecules of different length, including the molecules with uniform, diblock and alternating distribution of the charge are studied. Theoretical predictions are in reasonable agreement with available computer simulation predictions. We present also the liquid-gas phase diagrams for the systems with diblock and alternating distribution of the charge.Comment: Submitted to J. Chem. Phys. December 15, 200

Second-order resummed thermodynamic perturbation theory for central-force associating potential: Multi-patch colloidal models

We propose a second-order version of the resummed thermodynamic perturbation theory for patchy colloidal models with arbitrary number of multiply bondable patches. The model is represented by the hard-sphere fluid system with several attractive patches on the surface and resummation is carried out to account for blocking effects, i.e., when the bonding of a particle restricts (blocks) its ability to bond with other particles. The theory represents an extension of the earlier proposed first order resummed thermodynamic perturbation theory for central force associating potential and takes into account formation of the rings of the particles. In the limiting case of singly bondable patches (total blockage), the theory reduces to Wertheim thermodynamic perturbation theory for associating fluids. Closed-form expressions for the Helmholtz free energy, pressure, internal energy, and chemical potential of the model with an arbitrary number of equivalent doubly bondable patches are derived. Predictions of the theory for the model with two patches appears to be in a very good agreement with predictions of new NVT and NPT Monte Carlo simulations, including the region of strong association

Phase coexistance in polydisperse mixture of hard-sphere colloidal and flexible chain particles

A theoretical scheme for the calculation of the full phase diagram (including cloud and shadow curves, binodals and distribution functions of the coexisting phases) for colloid-polymer mixtures with polymer chain length polydispersity and hard-sphere colloidal and polymeric monomer sizes polydispersity is proposed. The scheme combines thermodynamic perturbation theory for associating fluids and recently developed method used to determine the phase diagram of polydisperse spherical shape colloidal fluids (L.Bellier-Castella {\it et al.}, {\it J.Chem.Phys.} {\bf 113}, 8337(2000)). By way of illustration we present and discuss the full phase diagram for the mixture with polydispersity in the size of the hard-sphere colloidal particles.Comment: 6 pages, 4 figure

Liquid-gas phase behavior of Stockmayer fluid with high dipolar moment

A multi-density version of the thermodynamic perturbation theory for associative fluids with central force associative potential is developed. The theory is used to describe the liquid-gas phase behavior of Stochmayer fluid with different values of the dipole moment ranging from low to high. Results of the theory are in a reasonable agreement with corresponding computer simulation results in a whole range of the dipole moment values studied. Contrary to previous computer simulation findings our calculations predict the occurrence of the liquid-gas phase coexistence for the soft-sphere dipole fluid model.Запропонований багатогустинний варiант термодинамiчної теорiї збурень для асоцiйованих рiдин з асоцiативним потенцiалом взаємодiї типу центральних сил. Розвинута теорiя використана для опису фазової поведiнки рiдина-газ моделi Штокмаєра з рiзними значеннями дипольного моменту, якi змiнюються вiд низького до високого. Результати теорiї є у задовiльнiй згодi з вiдповiдними результатами комп’ютерного моделювання для всiх значень дипольного моменту. На вiдмiну вiд розрахункiв, виконаних ранiше методами комп’ютерного моделювання, нашi розрахунки передбачають iснування фазової рiвноваги рiдина-газ в моделi м’яких дипольних сфер

Classical molecular simulations of complex industrially-important systems on the Intel Paragon

Advances in parallel supercomputing now make possible molecular-based engineering and science calculations that will soon revolutionize many technologies, such as those involving polymers and those involving aqueous electrolytes. We have developed a suite of message-passing codes for classical molecular simulation of such complex fluids and amorphous materials and have completed a number of demonstration calculations of problems of scientific and technological importance with each. In this overview paper we will outline the techniques for classical molecular simulation of these industrially-important systems on the Inter Paragon and we will summarize some of the important scientific and technical results of the varied applications, including the following: (1) Parallel codes for quatemion dynamics using techniques for handling long-range Coulombic forces allow study of ion pairing in supercritical aqueous electrolyte solutions. Ion pairing lies at the heart of technological problems with corrosion and solids deposition in industrial processes utilizing high temperature water. (2) Non-equilibrium, multiple time step molecular dynamics lets us investigate the rheology of molecular fluids. Such calculations enable the molecular-based design of new synthetic lubricants of importance in the automotive engines of the future. (3) Chain molecule Monte Carlo simulations in the Gibbs ensemble now permit calculation of phase equilibrium of long-chain molecular systems. With complementary equilibrium molecular dynamics (with multiple time steps) we have been able to gain fundamental insight into the technologically-important problem of liquid-liquid phase separation in polymer blends

Annual Research Review: interparental conflict and youth psychopathology: an evidence review and practice focused update

The quality of the interparental relationship is recognized as an important influence on child and adolescent psychopathology. Historically, clinically-oriented research on this topic has focused on the impacts of parental divorce and domestic violence as primary interparental relationship influences on child outcomes, to the relative neglect of dimensional or qualitative features of the couple/interparental relationship for youth (child and adolescent) psychopathology. Recent research has highlighted that children are affected by attributes of interparental conflict, specifically how parents express and manage conflicts in their relationship, across a continuum of expressed severity and negativity – ranging from silence to violence. Further, new evidence highlights that children’s emotional, behavioral, social, academic outcomes and future interpersonal relationships are adversely affected by conflict between parents/carers whether adults are living together or not (i.e. married or separated), or where children are or are not genetically related to their rearing parents (e.g. adoption). We review evidence and present an integrated theoretical model, highlighting how children are affected by interparental conflict and what this evidence base means for effective intervention and prevention program development, as well as the development of possible cost-benefit models. Additionally, we review policy implications of this research and highlight some very recent examples of UK-based policy focusing on addressing the interparental relationship and its impact on youth psychopathology

Adsorption-desorption kinetics in nanoscopically confined oligomer films under shear

The method of molecular dynamics computer simulations is employed to study oligomer melts confined in ultra-thin films and subjected to shear. The focus is on the self-diffusion of oligomers near attractive surfaces and on their desorption, together with the effects of increasing energy of adsorption and shear. It is found that the mobility of the oligomers near an attractive surface is strongly decreased. Moreover, although shearing the system forces the chains to stretch parallel to the surfaces and thus increase the energy of adsorption per chain, flow also promotes desorption. The study of chain desorption kinetics reveals the molecular processes responsible for the enhancement of desorption under shear. They involve sequences of conformations starting with a desorbed tail and proceeding in a very fast, correlated, segment-by-segment manner to the desorption of the oligomers from the surfaces.

Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c

Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures and 1 tabl

Breast cancer metastasis to gynaecological organs: a clinico-pathological and molecular profiling study

Breast cancer metastasis to gynaecological organs is an understudied pattern of tumour spread. We explored clinico-pathological and molecular features of these metastases to better understand whether this pattern of dissemination is organotropic or a consequence of wider metastatic dissemination. Primary and metastatic tumours from 54 breast cancer patients with gynaecological metastases were analysed using immunohistochemistry, DNA copy-number profiling, and targeted sequencing of 386 cancer-related genes. The median age of primary tumour diagnosis amongst patients with gynaecological metastases was significantly younger compared to a general breast cancer population (46.5 versus 60 years; p < 0.0001). Median age at metastatic diagnosis was 54.4, time to progression was 4.8 years (range 0-20 years), and survival following a diagnosis of metastasis was 1.95 years (range 0-18 years). Patients had an average of five involved sites (most frequently ovary, fallopian tube, omentum/peritoneum), with fewer instances of spread to the lungs, liver, or brain. Invasive lobular histology and luminal A-like phenotype were over-represented in this group (42.8 and 87.5%, respectively) and most patients had involved axillary lymph nodes (p < 0.001). Primary tumours frequently co-expressed oestrogen receptor cofactors (GATA3, FOXA1) and harboured amplifications at 8p12, 8q24, and 11q13. In terms of phenotype conversion, oestrogen receptor status was generally maintained in metastases, FOXA1 increased, and expression of progesterone receptor, androgen receptor, and GATA3 decreased. ESR1 and novel AR mutations were identified. Metastasis to gynaecological organs is a complication frequently affecting young women with invasive lobular carcinoma and luminal A-like breast cancer, and hence may be driven by sustained hormonal signalling. Molecular analyses reveal a spectrum of factors that could contribute to de novo or acquired resistance to therapy and disease progression.Jamie R Kutasovic, Amy E McCart Reed, Renique Males, Sarah Sim, Jodi M Saunus ... Liana Dedina ... et al