A promising novel high-capacity anode material for lithium-ion batteries based on a highly dispersed tin powder is considered. The powder has been obtained using pulsed electrochemical cathodic ...reduction on a titanium vibrocathode in an electrolyte based on a choline chloride–ethylene glycol ionic liquid. The discharge capacity of the anode material is 817 (mAh)/g, which is close to the theoretical specific electrochemical capacity of tin amounting to 924 (mAh)/g. The powder dispersion level and the morphology of tin crystals are determined. The particle size distribution for the fractions with an increased content of particles having a size less than 0.1 μm and the SEM images of grains having a rhombohedral shape are presented. For studying the reversibility of the aforementioned anode material, the following applied methods for electrochemical analysis under electrode charge and discharge have been used: cyclic voltammetry, galvanostatic cycling, and impedance spectroscopy. Changes in the characteristics of the electrode under study using equivalent circuits for impedance spectroscopy under the formation of a lithium–tin intermetallic compound, as well as change in the ratio between the diffusion coefficient of lithium ions at different stages of charge and at the initial stage are considered. It is shown that, when the charge capacity close to the theoretical value is reached, the intercalation can occur in two ways: through a solid-electrolyte film and through an intermetallic compound.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
—The mechanism of the electrochemical formation of WO
3
films on the surface of titanium, tin, and ITO electrodes is investigated under various regimes, including the deposition time τ = 2000–8000 s ...and the electrochemical potential of deposition on the cathode in the range from –0.4 to –1 V. A technique for the synthesis of peroxytungstic acid and a method of cathodic electrodeposition are presented. The studies carried out with tin and titanium extend the field of application of WO
3
films to technologies of chemical current sources and fuel cells.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Possibilities of tin powders obtainment from the choline chloride-ethylene glycol ionic liquid are considered. The tin reduction from an ionic liquid mechanism is confirmed via chronovoltametry, ...chronopotentiometry, transient potential and impedance spectroscopy methods. Said mechanism includes the trichlorostanite complexes reduction at current densities up to 5 mA / cm2, recovery from a polyanionic adsorbed layer at current densities of 5-12 mA/cm2 and recovery from a mixed layer including polyanions bound and by electrolyte ions at current densities exceeding 12 mA/cm2. Tin ions reduction from the mixed coating layer facilitates forming of encapsulated tin powder particles with shape of symmetrical dendrites. Powders obtainment from an ionic liquid allows to reduce the resulting powder dispersion.
This article presents the research on the effect of substrate nature and electrolysis modes on ultramicron and nanosized electrolytic powders formation regularities. It was found that the ...preliminarily electropolishing of titanium cathode in combination with impulse electrolysis mode for nickel and copper powders obtaining provides for the predomination of nanosized fraction. The presence of water soluble polymers in the electrolyte for copper powder obtaining, polyvinylpyrrolidone (PVP) and polyacrilamide (PAA) allows forming stable dendritic powders with low agglomeration. Using of powders stabilized by polymers allows obtaining compositions with uniform particle distribution across the whole volume of the sample which provides for heightened wear resistance of composition materials.
The principles of pulse electrolysis modes selection and their effect on the size distribution of the powder electrolytic copper in electrolyte with additions of water-soluble polymers, ...polyvinylpyrrolidone (PVP) and polyacrylamide (PAA) are considered in the paper. The research conducted with use of chronopotentiometry and potential transients as well as a simulation model of the electrocrystallisation process showed that the values of pulse duration were greater than the transient time of electroactive species and the pause duration equal to the linear part of potential transient was optimum to obtain a powder with a predominant fraction of nanoscale particles . PVP and PAA additives help to reduce the average particle size in the nanoscale fraction copper powder particles to 25-40 nm. Selected current pulse mode effect corresponds to the reduction of the emergence of new centers of crystallization probability and the adatoms on the surface of the cathode movement probability.
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Molecules of the peptide H-(RADA)
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-OH in aqueous salt solutions are able of forming bilayer fibrils in the form of a biotropic material, which is suitable as a substrate for the growth and ...differentiation of vertebrate cells. In the filament, two β-sheets interact with hydrophobic surfaces formed by methyl groups of alanine residues. The charged groups of arginine and aspartic acid residues are exposed to the outside, while the peptides which make up the filament are in the β-conformation. Fibrils have two external hydrophilic layers, while a hydrophobic one is situated in between of them. Biogels from the H-(RADA)
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-OH peptide are considered as a prominent structure to design extracellular media aimed to culture different types of cells. Little is known about the detailed filament structure and peptide chain composition in two β-sheets. We have designed and studied the molecular dynamics of bilayered protofilament structures, whose β-sheets are composed either of parallel or antiparallel peptide chains. The method of molecular dynamics was used to study H-(RADA)
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-OH peptide complexes at 80 and 300 K. While the most stable peptide complex was found to consisting of antiparallel peptides, had the lowest free energy and the least deviation of atom coordinates, yet another stable structure of the peptide complex was identified as a 24-mer complex of parallel peptides with two β-sheets placed in
syn
orientation. These results further underlined the importance of factors which direct the initial stages of the H-(RADA)
4
-OH self-assembling in solution.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This paper describes the results of studies on the synthesis and functionalization of the surface of nanoscale and ultradispersed copper powders in the production process. The principles of ...deagglomeration and specific problems for Nanoparticles are considered. The paper presents data on stabilization of copper nanoparticles in the process of obtaining, highlights the problems that require a good understanding, namely the study of the behavior of different types of ultra and nanoscale copper powders in the processes related to production of polymeric composite materials.
The article focuses on the influence of human leukemia differentiation factor (HLDF), carcinoembryonic antigen (CEA), and polyclonal activators (PA) on cytokine production by peripheral blood cells ...in breast cancer and benign breast diseases. It was found that the influence of internal factors on the production of cytokines by the peripheral blood cells is associated with lymphatic metastasis (CEA: IL-10; HLDF: IL-6, IL-1β, TNF-α, and G-CSF). One special circumstance was that there were no differences between the production of cytokines by peripheral blood cells in the patients with breast cancer compared to the patients with benign breast diseases with a high risk of malignant transformation. This is evidence of the functional similarity of peripheral blood cells in patients with these conditions. Cytokine production under the influence of PA was different only in case of TNF-α in all study groups.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The good wear-resistance of state-of-the-art liquid lubricants is due to the formation of complex metal and organometallic films onto the friction surface, reducing the friction and wear. For this ...purpose, various additives of metal nanopowders are used, especially ones based on copper. The formation and growth of Cu nanoparticles, as well as the tribotechnical characteristics of lubricants, are mainly affected by the choice of stabilizer, because nanoparticles cannot resist the external conditions without protecting their surface. According to quantum chemical studies, the best stabilizer in the series of gelatin, ammonia, sodium borohydride, and sodium citrate is gelatin due to the very large amount of functional groups in its structure. The characterization of physicochemical properties via dynamic light scattering, atomic force microscopy, and electron microscopy, as well as the tribotechnical characteristics of liquid lubricants with stabilized Cu nanoparticles, are consistent with quantum chemical calculations, confirming that Cu nanoparticles stabilized in gelatin possess the better tribotechnical properties than other stabilizers.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The cellular response to DNA damage protects the essential information stored in the genome. This mechanism is crucial in terms of the cancer prevention and aging progression. The DNA damage response ...(DDR) consists of a complex network controlling the cell cycle and multiple mechanisms of the DNA repair. The DDR disruption is a cornerstone feature of the tumor cells, which allows them to enhance beneficial mutations that prevent successful disease treatment. The important checkpoints of the DDR are currently poorly understood due to the complexity and diversity of the DNA repair machinery. Histone ubiquitination is intensively involved in the repair of the double-stranded DNA breaks. This post-translational modification is known to be a key factor in the recruitment of the repair factors to the DNA damage sites. Here, the crucial role of the ubiquitin lysine residue K27 in the process of histone H2A monoubiquitination mediated by the ubiquitin ligase RNF168 has been showed. The presented data suggest forced and intensive diffusion of ubiquitin from the cytoplasm to the nucleus, which is characterized by the dynamic equilibrium less than 10 min. The comparison of the turnover rate of the wild-type ubiquitin and its variant with a single functional lysine residue K27 suggests an important role of the ubiquitin deposition as a covalent conjugate with histone H2A in terms of the stability of the entire ubiquitinome.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
