We performed a quantitative study of the neuronal population in the spinal cord of mice with acute and chronic model of experimental autoimmune encephalomyelitis. Immunohistological/immunofluorescent ...analysis with motor neuron marker ChAT revealed a significant decrease in the number of motor neurons in the ventral horns of the lumbar spinal cord in the acute form of autoimmune encephalomyelitis, with the further appearance of large empty (containing no motor neurons) areas in the ventral horns in the chronic form. The development of experimental autoimmune encephalomyelitis is accompanied by degradation and death of neurons, in particular ChAT
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motor neurons.
The method of continuous pressure decrease has been used to investigate limiting (attainable) stretches of ethane-nitrogen solutions. Experiments were conducted at temperatures of 260, 266, 270, and ...276 K and at nitrogen concentrations in the solution of 0.5 and 1.5 mol%. Pressure decrease rates were taken in the range 0.01-0.1 MPa/s. Distribution functions of liquid boiling-up events in dependence on pressure have been obtained allowing one to determine the most probable (attainable) pressures of liquid boiling-up and the nucleation rate. The results are interpreted in terms of nucleation thermodynamics and kinetics in liquids on a solid surface containing inclusions that initiate the boiling-up processes. It is shown that for realizing homogeneous nucleation it is not necessarily required that the wettability is close to the ideal one. The reasons for the discrepancy between experimental data and predictions of homogeneous nucleation theory at nucleation rates J < 3 x 10 super(6) s super(-1) m super(-3) are discussed.
A new electrochemical approach which gives important knowledge about effect of the activation potentials range on the catalysts activity in ORR. The results obtained show how optimization of the ...pretreatment conditions of PtCu/C catalysts can significantly increase their operation characteristics due to the reorganization of the surface of nanoparticles.
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•Easy preparation of PtCu/C alloy nanocatalysts by one-pot wet-synthesis methods.•An active surface of bimetallic nanoparticles formed by electrochemical activation.•The peculiarities of the Cu atoms dissolution affect the activity of de-alloyed PtCu NPs.•PtCu/C catalysts activity in the ORR depends on the Upper potential limit at the activation stage.•Activation of PtCu/C catalysts at the UPL above 1.05 V leads to a significant decrease in their ORR activity.
The nanostructured PtCux/C catalysts with an average nanoparticle size of 3–5 nm, which significantly surpass in activity the commercial Pt/C analog in the oxygen electroreduction reaction (ORR), were obtained by the chemical reduction. A detailed analysis of the activation potentials range effect on the catalysts electrochemical performance in particular, on the microstructure of bimetallic catalysts with small nanoparticles, has been carried out. The upper potential limit, which limited the range of the electrode activation potentials, had a significant effect on the PtCu/C catalysts mass activity and specific activity in the ORR, but does not affect to the electrochemically surface area and materials compositions. Thus, an important phenomenon has been noted in which materials with the same composition differ significantly in their functional characteristics in the ORR, depending on the electrochemical activation conditions. Original approach to electrochemical study is presented, which helps to understand the effect of the activation potentials range on the surface layers reorganization of bimetallic nanoparticles in catalysts.
The proposed International Linear Collider (ILC) is well-suited for discovering physics beyond the Standard Model and for precisely unraveling the structure of the underlying physics. The physics ...return can be maximized by the use of polarized beams. This report shows the paramount role of polarized beams and summarizes the benefits obtained from polarizing the positron beam, as well as the electron beam. The physics case for this option is illustrated explicitly by analyzing reference reactions in different physics scenarios. The results show that positron polarization, combined with the clean experimental environment provided by the linear collider, allows to improve strongly the potential of searches for new particles and the identification of their dynamics, which opens the road to resolve shortcomings of the Standard Model. The report also presents an overview of possible designs for polarizing both beams at the ILC, as well as for measuring their polarization.
Platinum–carbon catalysts are widely used in the manufacturing of proton-exchange membrane fuel cells. Increasing Pt/C activity and stability is an urgent task and the optimization of their structure ...seems to be one of the possible solutions. In the present paper, Pt/C electrocatalysts containing small (2–2.6 nm) nanoparticles (NPs) of a similar size, uniformly distributed over the surface of a carbon support, were obtained by the original method of liquid-phase synthesis. A comparative study of the structural characteristics, catalytic activity in the oxygen electroreduction reaction (ORR), and durability of the synthesized catalysts, as well as their commercial analogs, was carried out. It was shown that the uniformity of the structural and morphological characteristics of Pt/C catalysts makes it possible to reduce the negative effect of the small size of NPs on their stability. As a result, the obtained catalysts were significantly superior to their commercial analogs regarding ORR activity, but not inferior to them in terms of stability.
The majority of prospective deposits of oil and natural gas in the Russian Federation are located in the zones of permanently frozen rocks - the permafrost. This region is characterized not only by ...harsh climatic conditions, causing difficulty in development of the deposits, but also by negative cryogenic processes impacting the reliability of construction and use of various engineering structures. It is necessary to know the regularities of and to be able to forecast the thermal regime of the soils and rocks in order to forecast the degree of influence of cryogenic processes on the engineering structures. In particular, the depth of thawing and freezing of soils in the locations of underground and surface structures, such as pipelines, is of importance. The depth of thawing of soil is an important indicator for the choice of the method of construction on the frozen surfaces. Control of the thawing/freezing depth can be ensured with the use of thermal insulation as well as replacement of the soil itself with an artificial soil with preselected properties. Transportation of oil and natural gas is realized using pipelines laid through frozen rocks. In order to decrease cryogenic impact on the pipes, special thermal insulation beddings replacing a section of soil are used. To determine the thermal insulation properties of beddings made out of polystyrene, variant calculations of thermal conductivity coefficient have been done according to the Odelevski and Schwerdtfeger formulas. Calculations were done for beddings in thawed and frozen state with different polystyrene content concentration. The conclusion is that both formulas can be used for theoretical determination of thermal conductivity coefficient. Absolute and relative errors do not exceed those permissible in engineering calculations for a wide range of conditions.
•(ZnO/C)25 multilayers show signatures of local ferromagnetic order at T≤ 120 K.•At T≤ 20 K, magnetoresistance (MR) changes its sign twice in the range B = 0–20 T.•The MR behaviour is associated with ...three competing mechanisms.
A layer-by-layer sputtering method was used to fabricate nanostructures (ZnO/C)25 composed of zinc oxide and carbon alternating layers, with a total multilayer thickness of 146 nm and 153 nm. At low temperatures, the multilayers show signatures of local ferromagnetic order: magnetic hysteresis, weak magnetization and the characteristic shape of the thermomagnetic curve. In-plane and out-of-plane magnetoresistance (MR) was measured in a pulsed magnetic field up to 20 T in the temperature range of 15–300 K. At T ⩽ 20 K, MR changed its sign from negative in low magnetic fields to positive in moderate fields, and then back to negative in high magnetic fields. At T ⩾ 80 K, MR was negative in the full range of magnetic fields studied. The unusual MR behavior can be associated with the influence of the Zeeman effect on the Fermi level position in the case of 2D variable hopping conduction along the interfaces, scattering on magnetic heterogeneities and the effect of magnetic blockade.
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