Application of vegetable oils for electrocatalytic synthesis of hydrocarbons

Conditions of Kolbe cross-electrosynthesis of 10-undecylenic and acetic acids are studied on different catalyst anodes. It is shown that the key anodic process stages are the stages of formation of vinyl radicals from anions of unsaturated and methyl radicals under electrosynthesis of acetate anions. As dependent on the conditions of the process, the main product formed on the anode of the Pt-10% Ir alloy is either hydrocarbon CH₃CH₂CH(CH₃)(CH₂)7CH₂CH₃ (58 wt %) being the product of addition of three methyl radicals to a vinyl radicals or olefin CH₂=CH(CH₂)₇CH₂CH₃ (57 wt %) being the product of dimerization of vinyl and methyl radicals.     

Thermochemical properties of gaseous and liquid polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and dibenzofurans

The analysis and systematization of the known and calculation of the unknown thermochemical characteristics (the standard enthalpy of formation, the standard entropy, the heat capacity, etc.) of widespread hazardous isomers of gaseous and liquid compounds of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans are carried out.     

Reactions of sodium tetrahydroborate with alkyl and aryl halides: A new approach to the synthesis of B3H 8 − and B12H 12 2− anions

A new method for the synthesis of the B₃H ₈ ^? anion based on the reactions of alkyl and aryl halides (C₂H₄Cl₂, C₆H₅CH₂Cl, C₄H₉Br, (C₆H₅)₃CCl, C₁₀H₇CH₂Cl, CH₂I₂, C₂HCl₃) with sodium tetrahydroborate in diglyme was proposed. The method is characterized by high (up to quantitative) yields and easy isolation of the target products, (n-C₄H₉)₄N)[B₃H₈] and Cs[B₃H₈], and also easy preparation of a salt of higher hydroborate anion, B₁₂H ₁₂ ^2? , without multistage purification from impurities of other anions of this series.     

Effect of the production temperature on the structure of Si<Subscript>3</Subscript>N<Subscript>4</Subscript> nanofibers

The effect of the production temperature on the morphology and structure of Si₃N₄ nanofibers was investigated. It was shown that nanofibers produced in the temperature range of 1340–1360°C are amorphous while those produced at 1380°C and above are monocrystalline. Apart from the principal phase (α-Si₃N₄) the imide Si₂N₂NH was also found in the reaction products.     

Synthesis and characterization of Li(I)-M(II) (M = Co, Ni) heterometallic complexes as molecular precursors for LiMO2

Lithium-containing heterometallic complexes with cobalt (Li₂Co₂(Piv)₆(2,4-Lut)₂ (2, Piv is the pivalate anion) and Li₂Co₂(O₂CCH₂Bu^t)₆(2,4-Lut)₂ (3)) and with nickel (Li₂Ni₂(Piv)₆(DME)₂ (4) and Li₂Ni₂(Piv)₆(2,2′-bpy)₂ (5)) were synthesized. The structures of the complexes were established by X-ray diffraction. The magnetic properties of complexes 2 and 4 were studied. The thermal behavior of compounds 2, 3, and 5 was investigated. It was shown that the compounds under study can be used as molecular precursors for the synthesis of lithium cobaltate and nickelate.     

Thermochemical properties of lithium cobaltate

Samples of low- and high-temperature modifications of LiCoO₂ were produced and described. The heat capacity was measured by DSC in the temperature ranges of 140–570 and 180–570 K, respectively. The enthalpy and entropy of the cobaltates with respect to temperature were calculated from the data of heat capacity.     

Absorption spectrum of H<Stack><Subscript>3</Subscript><Superscript>+</Superscript></Stack> near 1.06 μm

The absorption spectra of molecular hydrogen plasma excited by electric hollow-cathode and high-frequency discharges are measured. The spectra in the region of 1.06 μm were recorded using a neodymium intracavity laser spectrometer with a resolution of 0.03 cm^?1 and an absorption sensitivity of 10^?8 cm^?1. The absorption lines that can be attributed to the transitions to vibrational states in the molecule are recorded.     

Giant transversal Kerr effect in magneto-plasmonic heterostructures: The scattering-matrix method

The magneto-optical intensity effect (transversal Kerr effect) in a metal-dielectric periodic heterostructure that consists of a metallic grating formed by subwavelength slits and a dielectric substrate magnetized along the slits is shown to be resonantly enhanced by several tens of times in the excitation region of structure eigenmodes—surface plasmon polaritons and Fabry-Perot modes. The Fourier modal and scattering-matrix methods adapted to the case of gyrotropic periodic media have been used. The resonant enhancement of the intensity effect is attributable to the phenomenon of magneto-optical nonreciprocity.     

Flash Sintering of Oxide Ceramics under Microwave Heating

We report on the results of the analysis of the effect of flash sintering, which is observed upon heating compacted powder materials by high-intensity microwave radiation. Ceramic samples of Y₂O₃, MgAl₂O₄, and Yb: (LaO)₂O₃ were sintered to a density exceeding 98–99% of the theoretical value during 0.5–5 min without isothermal hold. The specific microwave power absorbed volumetrically in the samples was 20–400 W/cm³. Based on the analysis of the experimental data (microwave radiation power and heating and cooling rates) and of the microstructure of the obtained materials, we propose a mechanism of flash sintering based on the evolution of the thermal instability and softening (melting) of the grain boundaries. The proposed mechanism also explains the flash sintering effect observed when a dc or a low-frequency ac voltage is applied to the samples. The microwave heating makes it possible to implement flash sintering without using electrodes for supplying energy to the articles being sintered.     

Semiconductor-metal transition in FeSi in an ultrahigh magnetic field

We study the conductivity and magnetic susceptibility of single-crystal iron monosilicide in ultrahigh magnetic fields (up to 500 T) at low temperatures. The experimental methods used in measuring the conductivity and magnetic susceptibility are discussed. At 77K we detect a gradual increase in the conductivity of iron monosilicide by more than a factor of 100 as the magnetic field gets stronger. At 4.2K we detect a first-order phase transition in a field of 355 T accompanied by a sudden change in the value of the magnetic moment by 0.95 μ _B per iron atom and a transition to a phase with high conductivity. The results are discussed within the scope of the spin-fluctuation theory. Zh. éksp. Teor. Fiz. 116, 1770–1780 (November 1999)