Method for splitting into physical processes in the problem on the time dynamics of electron wave functions of a two-dimensional quantum ring

A variant is proposed of the method for splitting into physical processes intended to resolve the problem on the time dynamics of electron wave functions of a two-dimensional quantum ring. A new numerical analytical algorithm has been worked out on the basis of the developed technique. The results are presented of applying this method to the solution of the model problem. The efficiency of the numerical analytical method was compared with the effectiveness of numerical methods such as shooting and double sweep.     

Poly(imide-amide)-poly(ethylene glycol) hybrid networks: nanostructure,molecular dynamics and membrane properties

Summary Nanometer-scale structure, molecular dynamics (at 100-580 K) and membrane properties were studied in two series of poly(imide-amide) (PIA)-poly(ethylene glycol) (PEG) hybrid networks with regularly varied composition and different lengths of PEG crosslinks (M_n= 1000 or 3400). Combined WAXD/SAXS/polarized microscopy/DSC/DRS/TSDC/creep rate spectroscopy (CRS) analysis of these hybrids was performed. Depending on their composition, semicrystalline or mesomorphous, or amorphous state, and nanostructural heterogeneity were observed for these networks. They could be subdivided into (a) the PIA-rich hybrids with spatially isolated PEG domains, “suppressed” dynamics in the PEG glass transition, and PIA domains with T_g=520–570 K (group 1), and (b) the other hybrids with a continuous PEG phase and low-temperature glass transition only (group 2). Heterogeneity in segmental dynamics was revealed by CRS over the temperature range from T_g^PEG to T_g^PIA. In the second group of hybrids, the permeability coefficients were higher, by two or three orders of magnitude, for organic vapors than those for air gases.     

Organometallic polymer-derived interfacial coatings on carbon and SiC fibers

Organosilicon and organogermanium polymers containing unsaturated carbon–carbon bonds were used as precursors for the SiC-based interfacial coatings on commercially available carbon and silicon carbide fibers and fabrics. The approach based on usage of the organometallic polymer solutions allowed to obtain uniform, adherent, crack-free and non-bridging SiC-based interfacial coatings on carbon and SiC fibers. The coated fibers retain their tensile strength. The morphology, composition, structure of coated fibers were evaluated by various analytical techniques. The drop-like germanium-containing phase was detected in the organogermanium polymer-derived coating on carbon and SiC fibers.     

Unusual Magnetic Phase Transitions in Gd<Superscript>3+</Superscript> Clusters in Multicomponent Oxide Glasses

Magnetic susceptibility, EPR and optical properties have been studied in a glass system {20La₂O₃−22Al₂O₃−23 B₂O₃−35(SiO₂+GeO₂)} with a part of La₂O₃ substituted by Gd₂O₃ in different concentrations. Positive Weiss constants have been found in more heavily doped glasses; two magnetic transitions at 55 and 12 K have been detected and ascribed, respectively, to ferromagnetic and antiferromagnetic clusters of Gd³⁺ ions. The EPR spectra confirm the clustering at higher Gd contents. At low temperatures the cluster-related resonance indicates an onset of magnetic anisotropy. The clustering, depending on the Gd concentration, correlates with a shift to lower energies of the strong optical absorption band edge.     

Plasma-Assisted Chemistry in High-Speed Flow

Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow.     

Synaptamide Improves Cognitive Functions and Neuronal Plasticity in Neuropathic Pain

Neuropathic pain arises from damage or dysfunction of the peripheral or central nervous system and manifests itself in a wide variety of sensory symptoms and cognitive disorders. Many studies demonstrate the role of neuropathic pain-induced neuroinflammation in behavioral disorders. For effective neuropathic pain treatment, an integrative approach is required, which simultaneously affects several links of pathogenesis. One promising candidate for this role is synaptamide (N-docosahexaenoylethanolamine), which is an endogenous metabolite of docosahexaenoic acid. In this study, we investigated the activity of synaptamide on mice behavior and hippocampal plasticity in neuropathic pain induced by spared nerve injury (SNI). We found a beneficial effect of synaptamide on the thermal allodynia and mechanical hyperalgesia dynamics. Synaptamide prevented working and long-term memory impairment. These results are probably based on the supportive effect of synaptamide on SNI-impaired hippocampal plasticity. Nerve ligation caused microglia activation predominantly in the contralateral hippocampus, while synaptamide inhibited this effect. The treatment reversed dendritic tree degeneration, dendritic spines density reduction on CA1-pyramidal neurons, neurogenesis deterioration, and hippocampal long-term potentiation (LTP) impairment. In addition, synaptamide inhibits changes in the glutamatergic receptor expression. Thus, synaptamide has a beneficial effect on hippocampal functioning, including synaptic plasticity and hippocampus-dependent cognitive processes in neuropathic pain.     

Gut Microbiota as a Mediator of Essential and Toxic Effects of Zinc in the Intestines and Other Tissues

The objective of the present study was to review the existing data on the association between Zn status and characteristics of gut microbiota in various organisms and the potential role of Zn-induced microbiota in modulating systemic effects. The existing data demonstrate a tight relationship between Zn metabolism and gut microbiota as demonstrated in Zn deficiency, supplementation, and toxicity studies. Generally, Zn was found to be a significant factor for gut bacteria biodiversity. The effects of physiological and nutritional Zn doses also result in improved gut wall integrity, thus contributing to reduced translocation of bacteria and gut microbiome metabolites into the systemic circulation. In contrast, Zn overexposure induced substantial alterations in gut microbiota. In parallel with intestinal effects, systemic effects of Zn-induced gut microbiota modulation may include systemic inflammation and acute pancreatitis, autism spectrum disorder and attention deficit hyperactivity disorder, as well as fetal alcohol syndrome and obesity. In view of both Zn and gut microbiota, as well as their interaction in the regulation of the physiological functions of the host organism, addressing these targets through the use of Zn-enriched probiotics may be considered an effective strategy for health management.     

A Comparative Characterization of Kaolins of Provenance from the Prosyanovskoe and Kyshtymskoe Deposits Subjected to Mechanochemical Activation in an Aqueous Medium

The effect of mechanical activation in an aqueous medium on properties of kaolins of provenance from the Prosyanovskoe and Kyshtymskoe deposits — typical representatives of high-grade and low-grade kaolins — is studied. The activation in an aqueous medium produces a substantial effect on the crystallinity of kaolins and the process of phase formation in heat-treated kaolins. The mechanochemical activation, backed up by an accumulated and systematized experimental data, can provide a simple and readily available way toward improving the quality of kaolins.     

Molecular dynamics simulation of a flexible polymer network in a liquid crystal solvent; structure and equilibrium properties

A flexible regular tetrafunctional polymer network containing a low molecular liquid crystal (LC) solvent was simulated with molecular dynamics. The LC solvent comprises of anisotropic rod-like semi-flexible linear molecules composed of beads bonded by a FENE potential. Flexibility was induced by a bending potential proportional to the cosine of the angle between neighbouring valence bonds. All interactions between non-bonded beads are described by the repulsive part of the Lennard-Jones potential. The average length of the network chain was chosen to be close to the length of a mesogen. The number of network cells was constant and the simulated systems differ from each other by the number of LC layers. The simulations of a system of flexible polymer chains in a low molecular LC solvent and a system of pure low molecular LC solvent were also carried out. Increasing the density of the composite system the LC solvent experiences the same phase transition as the pure LC: isotropic, nematic and smectic. The presence of the network shifts the isotropic-nematic transition to higher densities but does not significantly change the position of nematic-smectic transition. Transition of the LC solvent into the smectic state changes the morphology of the network. The periodicity of LC phase determines the number of network layers. The presence of linear chains in the LC solvent decreases the number of LC layers in the smectic phase.The LC order induces some stretching of the network chains along the direction of orientation and at the same time causes shrinkage in the perpendicular direction especially in the smectic phase.