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71.
V. A. Kolotygin E. V. Tsipis A. I. Ivanov Y. A. Fedotov I. N. Burmistrov D. A. Agarkov V. V. Sinitsyn S. I. Bredikhin V. V. Kharton 《Journal of Solid State Electrochemistry》2012,16(7):2335-2348
Strontium additions in (La1?x Sr x )1?y Mn0.5Ti0.5O3?δ (x?=?0.15–0.75, y?=?0–0.05) having a rhombohedrally distorted perovskite structure under oxidizing conditions lead to the unit cell volume contraction, whilst the total conductivity, thermal and chemical expansion, and steady-state oxygen permeation limited by surface exchange increase with increasing x. The oxygen partial pressure dependencies of the conductivity and Seebeck coefficient studied at 973–1223?K in the p(O2) range from 10?19 to 0.5?atm suggest a dominant role of electron hole hopping and relatively stable Mn3+ and Ti4+ states. Due to low oxygen nonstoichiometry essentially constant in oxidizing and moderately reducing environments and to strong coulombic interaction between Ti4+ cations and oxygen anions, the tracer diffusion coefficients measured by the 18O/16O isotopic exchange depth profile method with time-of-flight secondary-ion mass spectrometric analysis are lower compared to lanthanum–strontium manganites. The average thermal expansion coefficients determined by controlled-atmosphere dilatometry vary in the range 9.8–15.0?×?10?6?K?1 at 300–1370?K and oxygen pressures from 10?21 to 0.21?atm. The anodic overpotentials of porous La0.5Sr0.5Mn0.5Ti0.5O3?δ electrodes with Ce0.8Gd0.2O2-δ interlayers, applied onto LaGaO3-based solid electrolyte, are lower compared to (La0.75Sr0.25)0.95Cr0.5Mn0.5O3?δ when no metallic current-collecting layers are introduced. However, the polarization resistance is still high, ~2 Ω?×?cm2 in humidified 10?% H2–90?% N2 atmosphere at 1073?K, in correlation with relatively low electronic conduction and isotopic exchange rates. The presence of H2S traces in H2-containing gas mixtures did not result in detectable decomposition of the perovskite phases. 相似文献
72.
Antipov OL Bredikhin DV Eremeykin ON Savikin AP Ivakin EV Sukhadolau AV 《Optics letters》2006,31(6):763-765
Refractive-index changes accompanying changes in population of electronic levels of Yb3+ ions in a Yb:YAG laser disk under intense diode and laser pumping have been studied by use of both a highly sensitive polarization interferometer and transient grating testing at 633 nm. The electronic change of the index that is due to excitation of the Yb3+ ions (which have different polarizability of ground state 2F7/2 and excited level 2F5/2) is strongly predominant over the thermal component. The polarizability differences are deltap (1.9 +/- 0.8) x 10(-26) and (1.95 +/- 0.25) x 10(-26) cm3 as measured at 633 nm in interferometric and transient grating experiments, respectively. 相似文献
73.
74.
B. M. Bredikhin 《Journal of Mathematical Sciences》1980,14(1):869-887
The survey covers works on the additive number theory during the period 1954–1977. Results pertaining to the classical problems of Goldbach, Hardy-Littlewood, and analogous problems are considered.Translated from Itogi Nauki i Tekhniki, Algebra, Topologiya, Geometriya, Vol. 16, pp. 5–33, 1978. 相似文献
75.
76.
M. Yu. Antipin Yu. T. Struchkov I. F. Shishkov A. V. Golubinskii T. L. El'fimova L. V. Vilkov A. A. Bredikhin A. N. Vereshchagin S. M. Ignatov V. F. Rudchenko R. G. Kostyanovskii 《Russian Chemical Bulletin》1986,35(10):2040-2046
Conclusions It has been established by the methods of x-ray diffraction analysis and electron diffraction analysis and measurements of the dipole moments and the birefringence that in the crystalline and gaseous phases, as well as in solution, N,N-dimethoxyamine has a gauche-gauche conformation, which is stipulated by a stabilizing nO-N-O* orbital interaction. The geometric parameters of the molecule have been determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2235–2242, October, 1986. 相似文献
77.
Bredikhin A. A. Bredikhina Z. A. Gubaidullin A. T. Litvinov I. A. 《Russian Journal of General Chemistry》2003,73(8):1282-1287
The stereoisomers of 5-phenoxy-1,3,2-dioxathiane 2-oxide both exist as chair conformers with an axial S = O bond. The features of conformational behavior, distinguishing this diastereomeric pair from earlier studied are explained in terms of the conformational energies of substituents in the 1,3-dioxane series. 相似文献
78.
Bredikhin A. A. Strunskaya E. I. Novikova V. G. Azancheev N. M. Sharafutdinova D. R. Bredikhina Z. A. 《Russian Chemical Bulletin》2004,53(1):213-218
The enantioselective partial hydrolysis of a number of racemic aryl glycidyl ethers in the presence of chiral Co(salen)-catalyst was studied. The enantiomeric composition of the isolated (R)-aryl glycidyl ethers was analyzed by 31P NMR using optically active substituted 2-chloro-1,3,2-dioxaphospholanes. A synthesis of -adrenoblocking agents (S)-toliprolol and (S)-moprolol based on the simultaneously obtained (S)-3-aryloxypropane-1,2-diols was proposed. 相似文献
79.
Ragnarsson U Grehn L Koppel J Loog O Tsubrik O Bredikhin A Mäeorg U Koppel I 《The Journal of organic chemistry》2005,70(15):5916-5921
The pK(a) values in DMSO for 22 di- and triprotected hydrazine NH acids and two monosubstituted hydrazines have been determined using potentiometric titration. The results of density functional theory calculations at the B3LYP/6-311+G level of gas-phase acidities of a representative selection of mono-, di-, and trisubstituted hydrazines are compared with both the relevant published and novel experimental titration data. In the course of this work, a rough estimation of the pK(a) value of hydrazine in DMSO (ca. 38.0) has been deduced. For typical triprotected compounds of this kind containing moderately electron-withdrawing carbamate and imidodicarbonate or arenesulfonylcarbamate functions the pK(a) values fall in the range 15.1-17.3, whereas for N,N'-diprotected hydrazines with a carbamate and an aromatic sulfonyl group the corresponding values are 12.7-14.5. Several of these triprotected derivatives have recently been applied preparatively in stepwise synthesis of substituted hydrazines using alkyl halides as electrophiles in the presence of a phase transfer catalyst, and a few of them, with varying success, have been examined in model experiments with benzyl alcohol, triphenylphosphine, and diethyl azodicarboxylate in the Mitsunobu reaction. The dependence of the reactivity on the intrinsic acidity of the hydrazines in this reaction is highlighted. Furthermore, the regioselective alkylation of an N,N'-diprotected hydrazine can be rationalized on the basis of the presented data. 相似文献
80.
Conclusions p-Substituted phenyl chloromethyl ethers have a conformation with a gauche orientation of the C-Cl and C-O bonds; the aromatic ring is removed from the COC plane by 40°.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2720–2724, December, 1985. 相似文献