Effective interactions between star polymers and colloidal particles

Using monomer-resolved Molecular Dynamics simulations and theoretical arguments based on the radial dependence of the osmotic pressure in the interior of a star, we systematically investigate the effective interactions between hard, colloidal particles and star polymers in a good solvent. The relevant parameters are the size ratio q between the stars and the colloids, as well as the number of polymeric arms f (functionality) attached to the common center of the star. By covering a wide range of q's ranging from zero (star against a flat wall) up to about 0.75, we establish analytical forms for the star-colloid interaction which are in excellent agreement with simulation results. A modified expression for the star-star interaction for low functionalities, f < 10 is also introduced.Comment: 37 pages, 14 figures, preprint-versio

Soft Interaction Between Dissolved Dendrimers: Theory and Experiment

Using small-angle neutron scattering and liquid integral equation theory, we relate the structure factor of flexible dendrimers of 4th generation to their average shape. The shape is measured as a radial density profile of monomers belonging to a single dendrimer. From that, we derive an effective interaction of Gaussian form between pairs of dendrimers and compute the structure factor using the hypernetted chain approximation. Excellent agreement with the corresponding experimental results is obtained, without the use of adjustable parameters. The present analysis thus strongly supports the previous finding that flexible dendrimers of low generation present fluctuating structures akin to star polymers.Comment: 20 pages, 4 figures, submitted to Macromolecules on July 24, 200

НОВЫЕ РЕШЕНИЯ ПОВЫШЕНИЯ ЭКСПЛУАТАЦИОННОЙ УСТОЙЧИВОСТИ ГОРНЫХ ВЫРАБОТОК

Розглянуто два концептуальних підходи про початковий напружено- деформований стан навколо виробок різного призначення. Обґрунтовано наукові передумови зі створення кріплень нового технічного рівня. Представлено блок-схему реалізованих і перспективних заходів щодо створення нових конструкцій металорамних кріплень, які забезпечують ресурсозберігаючу експлуатаційну стійкість гірничих виробок для складних гірничо-геологічних умов. Рассмотрены два концептуальных подхода о начальном напряженно- деформированном состоянии в окрестности выработок различного назначения. Обоснованы научные предпосылки по созданию крепей нового технического уровня. Представлена блок-схема реализуемых и перспективных мероприятий по созданию новых конструкций металлорамных крепей обеспечивающих ресурсосберегающую эксплуатационную устойчивость горных вы- работок для сложных горно-геологических условий. Two conceptual approaches about initial stress-strain state in the vicinity of mine workings of various purpose are considered. Scientific preconditions focused on new technical level mine supports creation are substantiated. Block diagram of the realized and perspective measures focused on new constructions of metal- frame supports creation that provide resource-saving exploitation stability of mine workings for complex mining-geological conditions is presented

Crystallographic analysis of rock grain orientation at meso- and microscale levels

This paper studies the results of electron backscatter diffraction analysis of naturally deformedpolycrystalline olivine. It also defines the dependence of lattice-preferred orientations of grains on their microstructural position and size. The authors detect the basic mechanisms, consequence and thermal dynamic modes of deformation. They also show that the development of a polycrystalline structure is determined by the following consecutive activation of sliding systems (010)[100] → {0kl}[100] → (100)[010] → {100}[001] → {110}[001], when dislocation sliding and diffusion creep change under the temperature decrease from 1000°C to 650°C

Oral anticoagulant use in cardiovascular disorders: a perspective on present and potential indications for rivaroxaban.

BACKGROUND: Four nonvitamin K antagonist oral anticoagulants (NOACs) have been approved for use in various cardiovascular indications. The direct thrombin inhibitor dabigatran and the direct factor Xa inhibitors apixaban, edoxaban, and rivaroxaban are now increasingly used in clinical practice. For some of these agents, available data from real-world studies support the efficacy and safety data in phase III clinical trials. OBJECTIVES: This review aims to summarize the current status of trials and observational studies of oral anticoagulant use over the spectrum of cardiovascular disorders (excluding venous thrombosis), provide a reference source beyond stroke prevention for atrial fibrillation (AF) and examine the potential for novel applications in the cardiovascular field. METHODS: We searched the recent literature for data on completed and upcoming trials of oral anticoagulants with a particular focus on rivaroxaban. RESULTS: Recent data in specific patient subgroups, such as patients with AF undergoing catheter ablation or cardioversion, have led to an extended approval for rivaroxaban, whereas the other NOACs have ongoing or recently completed trials in this setting. However, there are unmet medical needs for several arterial thromboembolic-related conditions, including patients with: AF and acute coronary syndrome, AF and coronary artery disease undergoing elective percutaneous coronary intervention, coronary artery disease and peripheral artery disease, implanted cardiac devices, and embolic stroke of unknown source. CONCLUSION: NOACs may provide alternative treatment options in areas of unmet need, and numerous studies are underway to assess their benefit-risk profiles in these settings

HCV reinfection incidence and spontaneous clearance rates in HIV-positive men who have sex with men in Western Europe

BACKGROUND & AIMS: Moderate cure rates of acute hepatitis C virus (HCV) infections with pegylated interferon and ribavirin have been described in the last decade in men who have sex with men (MSM), who are also coinfected with the human immunodeficiency virus (HIV). However, a subsequent high incidence of HCV reinfections has been reported regionally in men who both clear the infection spontaneously or who respond to treatment. METHODS: Retrospective analysis of reinfections in HIV infected MSM in eight centers from Austria, France, Germany, and the UK within the NEAT network between May 2002 and June 2014. RESULTS: Of 606 individuals who cleared HCV spontaneously or were successfully treated, 149 (24.6%) presented with a subsequent HCV reinfection. Thirty out of 70 (43%) who cleared again or were successfully treated, presented with a second reinfection, 5 with a third, and one with a fourth reinfection. The reinfection incidence was 7.3/100 person-years (95% CI 6.2-8.6). We found a trend for lower incidence among individuals who had spontaneously cleared their incident infection than among individuals who were treated (Hazard ratio 0.62, 95% CI 0.38-1.02, p=0.06). Spontaneous clearance of reinfection was associated with ALT levels >1000IU/ml and spontaneous clearance of a prior infection. CONCLUSIONS: HCV reinfection is an issue of major concern in HIV-positive MSM. Prevention strategies are needed for high risk groups to reduce morbidity and treatment costs. HIV-positive MSM with a prior HCV infection should be tested every 3 to 6months for reinfection. Those who had achieved a reinfection should be tested every 3months. LAY SUMMARY: We evaluated the occurrence of HCV reinfection in HIV-positive men who have sex with men. We found an alarming incidence of 7.3/100 person-years. Prevention measures need to address this specific subgroup of patients at high risk for HCV

Phase separation in star polymer-colloid mixtures

We examine the demixing transition in star polymer-colloid mixtures for star arm numbers f=2,6,16,32 and different star-colloid size ratios. Theoretically, we solve the thermodynamically self-consistent Rogers-Young integral equations for binary mixtures using three effective pair potentials obtained from direct molecular computer simulations. The numerical results show a spinodal instability. The demixing binodals are approximately calculated, and found to be consistent with experimental observations.Comment: 4 pages, 4 figures, submitted to PR

Polydisperse star polymer solutions

We analyze the effect of polydispersity in the arm number on the effective interactions, structural correlations and the phase behavior of star polymers in a good solvent. The effective interaction potential between two star polymers with different arm numbers is derived using scaling theory. The resulting expression is tested against monomer-resolved molecular dynamics simulations. We find that the theoretical pair potential is in agreement with the simulation data in a much wider polydispersity range than other proposed potentials. We then use this pair potential as an input in a many-body theory to investigate polydispersity effects on the structural correlations and the phase diagram of dense star polymer solutions. In particular we find that a polydispersity of 10%, which is typical in experimental samples, does not significantly alter previous findings for the phase diagram of monodisperse solutions.Comment: 14 pages, 7 figure