Electrical and magnetic properties of [(CoFeZr)x(Al2O3)1 ? x/(α-SiH)]n multilayer structures

The concentration dependences of the electrical resistivity and complex permeability of [“(Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} ”/“α-Si: H”] _n multilayer structures and (Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} composites have been studied. It has been established that introduction of a semiconductor interlayer into the (Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} composites substantially decreases the electrical resistivity of [“(Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} ”/“α-Si: H”] _n multilayer structures. The concentration dependences of the real and imaginary parts of the complex permeability of the [“(Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} ”/“α-Si: H”] _n nanomultilayer structures substantially differ from those of the (Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} composites. The real part of the complex permeability of the [“(Co₄₅Fe₄₅Zr₁₀) _x (Al₂O₃)_{100 − x} ”/“α-Si: H”] _n nanomultilayer structures follows the curve with a minimum near the percolation threshold of the composite, and the imaginary part smoothly decreases as the ferromagnetic phase concentration increases. The results obtained are explained by the increase in the bifurcation temperature due to the conduction electrons of the semiconductor interlayer, which favor magnetic ordering of ferromagnetic grains.     

Application of a two-length-scale field theory to the solvation of neutral and charged molecules

We develop a continuous self-consistent theory of solute-water interactions that allows determination of the hydrophobic layer around a solute molecule of any geometry, with an explicit account of solvent structure described by its correlation function. We compute the mean solvent density profile n(r) surrounding the solute molecule as well as its solvation free energy deltaG. We compare the two-length-scale field theory to the numerical data of Monte Carlo simulations found in the literature for spherical molecules and discuss the possibility of self-consistent adjustment of the free parameters of the theory. In the framework of this approach, we compute the solvation free energies of alkane molecules and the free energy of interaction of two spheres of radius R separated by the distance D. We describe the general setting of the self-consistent account of electrostatic interactions in the framework of our model where the water is considered not as a continuous medium but as a gas of dipoles. We analyze the limiting cases where the proposed theory coincides with the electrostatics of a continuous medium.     

The Use of Raman Spectroscopy and Methods of Quantum Chemistry for Assessing the Relative Concentration of Triglycerides of Oleic and Linoleic Acids in a Mixture of Olive Oil and Sunflower Seed Oil

The Raman spectra of five samples of sunflower seed oil and five samples of cold-pressed olive oil of various brands are recorded in the range of 500–2000 cm^–1. Within the framework of the B3LYP/6-31G(d)/6-31G(d,p)/6-31+G(d,p)/6-311G(d)/6-311G(d, p)/6-311+G(d,p) methods, the structural models of eight fatty acids (oleic, linoleic, palmitic, stearic, α-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic) are constructed, and also within the framework of the B3LYP/6-31G(d) method, the structural models of triglycerides of the first four of the above acids are obtained. The vibrational wavenumbers and intensities in the IR and Raman spectra are calculated. The Raman spectra of olive oil and sunflower seed oil were simulated by using the supermolecular approach. We investigated the dependence of the relative intensity of the vibrational bands ν_exp = 1660 and 1445 cm^–1 on the concentration of triglycerides in oils of oleic and linoleic acids and the dependence of the intensity of these bands on the degree of saturation of fatty acids. Experimental and empirical dependences are constructed to estimate the relative concentration of triglycerides of oleic and linoleic acids in a mixture of olive oil and sunflower seed oil. The applicability of the density functional theory together with the vibrational spectroscopy for the identification of mixtures of vegetable oils is discussed.     

Astrophysical <Emphasis Type="Italic">S</Emphasis>-factor of T(<Superscript>4</Superscript>He, γ)<Superscript>7</Superscript>Li reaction at <Emphasis Type="Italic">E</Emphasis><Subscript>cm</Subscript> = 15.7 keV

The astrophysical S-factor of the reaction T(⁴He, γ)⁷Li is measured for the first time at the center of mass energy E _cm = 15.7 keV, lower than the energy range of the Standard Big Bang Nucleosynthesis (SBBN) model. The experiment is performed on a Hall pulsed accelerator (TPU, Tomsk). An acceleration pulse length of 10 μs allows one to suppress the background of cosmic radiation and the ambient medium by five orders of magnitude. A beam intensity of ~ 5 × 10^{14 4}He⁺ ions per pulse allows one to measure an extremely low reaction yield. The yield of γ-quanta with the energies E _γ ⁰ = 2483.7 keV and E _γ ¹ = 2006.1 keV is registered by NaI(Tl) detectors with the efficiency ε = 0.331 ± 0.026. A method for direct measurement of the background from the chain of reactions T(⁴He, ⁴He)T→T(T, 2n)X→(n, γ) and/or (n, n′γ) which ends by neutron activation of materials surrounding the target is proposed and implemented in this study. The value of the astrophysical S-factor of the reaction T(⁴He, γ)⁷Li S _αt (E _cm = 15.7 keV) = 0.091 ± 0.032 keV b provides the choice from the set of experimental data for the astrophysical S _αt -factor in favor of experimental data [4] with S _αt (E _cm = 0) = 0.1067 ± 0.0064 keV b.     

Self-oscillatory regimes of the penetration of vertical free turbulent jets through a liquid surface

The results of an experimental investigation of the penetration of vertical plane and round free turbulent jets through the surface of a liquid contained in a relatively narrow channel are presented. It is established that there exist the ranges of jet thicknesses, their velocities, and free region lengths, on which regular self-oscillatory regimes of the displacement of submerged jet regions and two-phase flow regions are observable. The mechanism of the generation of these regimes and the special features of the observable flows are discussed. The dependences of the self-oscillation periods on the main control parameters of the problem are established.     

Measurements of neutron fluxes with energies from thermal to several MeV in near-Earth space: SINP results

Neutron measurement results obtained at SINP MSU since 1970 are presented. These measurements were made using techniques based on neutron moderation and subsequent detection in a Li6I(Eu) crystal or a He3 coronal counter. The measurements were mainly carried out in orbits with inclination of 52 degrees and altitudes of 200-450 km. The spatial and angular distributions of the measured neutron fluxes were studied. The albedo neutron flux was estimated according to the count rate difference for opposite detector orientations towards Earth and away from it. This flux is comparable to the local neutron flux outside the Brazil anomaly region, where local neutrons dominate. Neutron fluxes, generated by solar protons, were detected during a solar flare on June 6, 1991 for the first time. Their spectrum was estimated as a power law with alpha>2.     

Microscopic description of low-energy neutron scattering on a deuteron

Low-energy neutron-deuteron scattering is calculated within the collective adiabatic approach by using a few versions of realistic NN interaction. The resulting integrated cross sections for the process are in good agreement with experimental data.     

Ion-beam modification of track membrane surface

An ion-beam method to modify the track membrane surface is suggested. An ion gun based on a magnetron sputterer is developed. This gun provides ion energies in the range of 5 eV–1 keV, ion current density up to 0.8 mA/cm², and an ion beam aperture of 90 mm. After the track membrane surface has been irradiated by argon ions with an energy of 50–100 eV, the angle of surface-water contact decreases from 65°–75° to 10°–25°. If the irradiating ion energy is 300–800 eV, the angle of contact increases from 65°–75° to 90°–100°.     

New Cysteine-Containing PEG-Glycerolipid Increases the Bloodstream Circulation Time of Upconverting Nanoparticles

Upconverting nanoparticles have unique spectral and photophysical properties that make them suitable for development of theranostics for imaging and treating large and deep-seated tumors. Nanoparticles based on NaYF₄ crystals doped with lanthanides Yb³⁺ and Er³⁺ were obtained by the high-temperature decomposition of trifluoroacetates in oleic acid and 1-octadecene. Such particles have pronounced hydrophobic properties. Therefore, to obtain stable dispersions in aqueous media for the study of their properties in vivo and in vitro, the polyethylene glycol (PEG)-glycerolipids of various structures were obtained. To increase the circulation time of PEG-lipid coated nanoparticles in the bloodstream, long-chain substituents are needed to be attached to the glycerol backbone using ether bonds. To prevent nanoparticle aggregation, an L-cysteine-derived negatively charged carboxy group should be included in the lipid molecule.     

The effect of an NH tautomerism on the structure and vibrational states of chlorin

A random sequence (path) of counts of an ideal detector, selective for energy states of an atom, at the output of a one-atom maser is simulated numerically by the Monte Carlo method. Fragments of a path for the cases in which a micromaser undergoes quantum jumps with an increase (jump up) or a decrease in the average number of photons in a mode are obtained. An idealized dynamic model of a quantum jump is formulated on the basis of the concept of a critical fluctuation, when several tens of atoms in the same state are detected successively. Approximate formulas for the dependence of the average number of photons and the rate of its change on the number of atoms passing through a cavity along a jump path are obtained. The probability of a quantum jump in the idealized model is estimated. It is shown that accounting for the nonideality of a jump increases its probability by several orders of magnitude. The high rate of a quantum jump up (the superpump effect) is attributed to the possibility of redistribution of photons between subensembles of the mode states. The probability of a nonideal quantum jump and the most likely number of interruptions (opposite escapes) in an ideal jump path are estimated.