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51.
52.
A. V. Ivanishchev A. V. Churikov A. S. Akmaev A. V. Ushakov I. A. Ivanishcheva I. M. Gamayunova M. J. Sneha A. Dixit 《Russian Journal of Electrochemistry》2017,53(3):302-311
Different approaches to synthesis of Li2FeSiO4-based electrode materials for lithium intercalation, using low-cost and abundant Li-, Si-, and Fe-containing parent substances, are discussed. XRD, SEM, and a laser-diffraction analyzer of particle size were used for structure and morphology characterization of the composite electrode materials. Li2FeSiO4 was shown to be the main lithium-accumulating crystalline phase; minor LiFeO2 and Li2SiO3 admixtures are also present. The material microparticles’ average size was shown to vary from tenths of micrometer to 1 μm. Larger objects sized ca. 2–4 μm are the microparticles’ agglomerates. The material electrochemical properties were studied by dc chronopotentiometry (galvanostatic charging–discharging) and cyclic voltammetry with potential linear sweeping. The initial reversible cycled capacity of the best samples is 170 mA h/g. The anodic and cathodic processes manifest obvious hysteresis caused by the presence of several different lithium ion energy states in the material; the transition between the states is kinetically hindered. The dependences of the specific capacity and its stability under cycling on the current load and the conductive carbon component content in the composite were elucidated. 相似文献
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M.?V.?Markova L.?N.?Sobenina I.?A.?Ushakov A.?V.?Ivanov B.?A.?TrofimovEmail author 《Russian Journal of Organic Chemistry》2017,53(2):184-191
Aminomethylation of 2-methyl(aryl)-, 2-aryl-3-alkylpyrroles, 4,5,6,7-tetrahydroindole and its 1-vinyl- and 1-benzyl-substituted derivatives with a mixture of 5% water-ethanol solution of formaldehyde and cyclic amine (pyrrolidine, piperazine, and morpholine) without catalyst at room temperature leads to the formation of the corresponding 2-aminomethylpyrroles and 2-aminomethyl-4,5,6,7-tetrahydroindoles in up to 92% yields. In reaction of 1-vinyl-4,5,6,7-tetrahydroindole with formaldehyde water solution and piperazine in a 60% yield 1,4-bis(1-vinyl-4,5,6,7-tetrahydroindol-2-yl)piperazine was obtained, a promising bifunctional monomer and a building block for the synthesis of new indole derivatives, in particular, of biologically active polymers. In the reaction of 2-methylpyrrole and 4,5,6,7-tetrahydroindole with formaldehyde and morpholine along with the С2-aminomethylation the 1-hydroxymethylation of the pyrrole ring was observed. 相似文献
55.
Elena Yu SchmidtNadezhda V. Zorina Elena V. SkitaltsevaIgor A. Ushakov Albina I. MikhalevaBoris A. Trofimov 《Tetrahedron letters》2011,52(29):3772-3775
Cyclohexanones react with phenylacetylene in a KOH/DMSO suspension (80 °C, 1 h) to give unexpectedly phenylmethylidene dispirocyclic ketals, 15-[(Z)-phenylmethylidene]-7,14-dioxadispiro[5.1.5.2]pentadecanes, in 16-22% yields (along with the anticipated β,γ- and α,β-ethylenic ketones). 相似文献
56.
Sergey V. Ushakov Divya Nag Alexandra Navrotsky 《Journal of Thermal Analysis and Calorimetry》2011,104(1):351-356
The severe heating of soil during wildfires and prescribed burns may result in adverse effects on soil fertility due to organic
matter loss. No rapid and reliable procedure exists to evaluate soil organic matter (SOM) losses due to heating. Enthalpy
of SOM combustion correlates with organic matter content. Quartz is a ubiquitous mineral in soils and has a remarkably constant
composition and reversible α–β phase transition at 575 °C. We suggest that SOM content in heated and unheated soils can be
compared using the ratio of SOM combustion enthalpy on heating to the β–α quartz transition enthalpy measured on cooling of
the same sample. This eliminates the need to dry and weigh the samples, making possible field applications of the proposed
method. The feasibility of using the (ΔH
comb SOM)/(ΔH
β–α Qz) ratio was established with experiments on soil samples heated in the laboratory and the method was then used for evaluation
of SOM loss on two pile burn sites at UC Berkeley’s Blodgett Forest Research Station in Georgetown, California. 相似文献
57.
Energy levels, wave functions, and matrix elements of optical dipole transitions have been numerically calculated for superlattice quantum-cascade structures. An expression for the gain has been obtained with regard to the complete set of energy levels in different models of spectral-line broadening. A universal relation between the gain and emission spectra for unipolar laser structures has been proposed. The effect of spectral broadening on the shape of emission spectra is estimated. The electroluminescence spectra are compared with the calculated spontaneous recombination spectra and good agreement between the results is shown. 相似文献
58.
The effect of conductivity and polarization of the solid and liquid phases on the pulsed electrical breakdown of suspensions was investigated. The variation of the suspension breakdown voltage with concentration of the disperse phase is attributed to distortion of the internal field due to impurity polarization and space-charge formation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 3, pp. 59–63, March, 1972. 相似文献
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