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The structural-phase states, microhardness, and tribological properties of hypoeutectic silumin after electron-beam treatment are studied by the methods of contemporary physical materials science. The object of the study is hypoeutectic АК10М2Н-type silumin containing 87.88 wt.% of Al and 11.1 wt.% of Si as the base components. The silumin surface is subjected to electron-beam treatment in six various regimes distinct in the density of electron-beam energy. The microhardness measurements of the modified silumin-surface layers enabled to determine three optimal impact regimes (with electron-beam energy densities of 25, 30, and 35 J/cm2), when the modified-layer microhardness exceeds that for the cast silumin. The obtained parameters are as follow: 0.86 ± 0.41 GPa for the cast state; 0.93 ± 0.52 GPa for 25 J/cm2; 0.97 ± 0.071 GPa for 30 J/cm2; 0.96 ± 0.103 GPa for 35 J/cm2. As found, the electron-beam treatment with the optimal parameters results in the formation of the surface whose mechanical and tribological characteristics sufficiently exceed corresponding values for the cast state of silumin. The atomic-force microscopy data correlate with the results on microhardness. The samples treated in the presented regimes are characterised with the fine-grained cellular structure and have the least roughness of the treated layer (of 17–33 nm) and substrate (of 45–57 nm) as compared to other regimes. As revealed, in the treated layer, the fine-grained, graded, and cellular structure is formed, and it transforms into the mixed-type structure when deepening away from the surface of treatment. Depending on the parameters of electron-beam treatment, the thickness of homogenized layer varies and reaches the maximum values of 100 μm at the energy density of 35 J/cm2. As detected, the modified layer is free from intermetallides and consists of the nanocrystalline structure of cellular crystallization. As assumed, these two factors are responsible for the increased mechanical and tribological characteristics of the modified layer. The formation mechanism for structure of cellular and columnar crystallization consisting in the initiation of thermocapillary instability over the ‘evaporated substance/liquid phase’ interface is offered. The mathematical model of the thermal effect of electron beam on the silumin-surface layers is developed.

For the solution of the problem of energy storage, new and more efficient functional electrode materials for electrochemical devices such as supercapacitors and their formation technologies are being developed. In particular, using the method of electrolyte-free electrophoretic codeposition, a composite material of carbon nanotubes (CNTs)/RuO2·xH2O with high specific capacitance and power values can be obtained. In this study, the optimal composition of a 50-mL suspension for electrophoretic deposition (EPD) is determined by sedimentation analysis. It is demonstrated that in the course of the iodoform reaction with acetone, I2 (20 mg) ensures the saturation of particle surfaces with protons and their deposition on the cathode, thus replacing the electrolytes that introduce impurities into the final coating. It is established that the presence of a dispersing agent (5 mg of hydroxypropyl cellulose) is required in the suspension to maintain stability. The possibility of removing hydroxypropyl cellulose during annealing in air at a temperature of about 260°C is studied and confirmed by the methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Composite material, processed in this way and obtained from a suspension containing double-walled CNTs and RuO2·xH2O, equal to 2 and 10 mg, respectively, has a capacity of 21.5 and 8.6 mF/cm2 at cyclic sweep rates of 10 and 100 mV/s, respectively. It is established that elevated temperatures and prolonged heat treatment lead to a deterioration in the electrochemical characteristics due to the degradation of RuO2·xH2O and the CNTs. [ABSTRACT FROM AUTHOR]

We present the most recent solar neutrino results from the Borexino experiment at the Gran Sasso underground laboratory. In particular, refined measurements of all neutrinos produced in the {\it pp} fusion chain have been made. It is the first time that the same detector measures the entire range of solar neutrinos at once. These new data weakly favor a high-metallicity Sun. Prospects for measuring CNO solar neutrinos are also discussed.

Currently, there is a growing demand for miniaturized power supplies, including planar supercapacitors, whose principle of operation is based on fast redox reactions. This circumstance stimulates investigations of composite structures made of high-surface-area carbon-based materials and transition-metal compounds. In this paper, we report the results of studying coatings based on few-layer graphite nanoflakes FLGN/Ni(OH)2 and their oxidized form OFLGN/Ni(OH)2, obtained by repeated electrophoretic deposition. These coatings are used in prototype parallel-plate (3D) and planar supercapacitors. A processing route using a 450-nm laser for pattern scribing is developed for the latter. It is shown that, by regulating the nickel-ion-source proportion in the suspension from 0.04 to 0.64 g/L, one can control the physical properties of the composite at the deposition stage. The composite's physical properties are studied by cyclic voltammetry, scanning microscopy, and elemental analysis. The peak capacity values are obtained for samples with the minimum concentration (0.04 g/L); they turn out to be 1.51 and 1.31 F/g for the FLGN-containing samples and 1.86 and 1.29 F/g for the OFLGN-containing samples of bulk and planar supercapacitors, respectively. [ABSTRACT FROM AUTHOR]