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131.
Acoustical Physics - Mathematical models of the phase function and its parameters in speech-signal analysis problems have been investigated. The phase spectrum of a speech signal has been... 相似文献
132.
Dr. Cédric Colomban Anthonio H. Tobing Gourab Mukherjee Dr. Chivukula V. Sastri Dr. Alexander B. Sorokin Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14320-14331
The biodegradation of compounds with C−F bonds is challenging due to the fact that these bonds are stronger than the C−H bond in methane. In this work, results on the unprecedented reactivity of a biomimetic model complex that contains an N-bridged diiron-phthalocyanine are presented; this model complex is shown to react with perfluorinated arenes under addition of H2O2 effectively. To get mechanistic insight into this unusual reactivity, detailed density functional theory calculations on the mechanism of C6F6 activation by an iron(IV)-oxo active species of the N-bridged diiron phthalocyanine system were performed. Our studies show that the reaction proceeds through a rate-determining electrophilic C−O addition reaction followed by a 1,2-fluoride shift to give the ketone product, which can further rearrange to the phenol. A thermochemical analysis shows that the weakest C−F bond is the aliphatic C−F bond in the ketone intermediate. The oxidative defluorination of perfluoroaromatics is demonstrated to proceed through a completely different mechanism compared to that of aromatic C−H hydroxylation by iron(IV)-oxo intermediates such as cytochrome P450 Compound I. 相似文献
133.
We show that a Hamiltonian reduction of affine Lie superalgebras having bosonic simple roots (such as OSp
) does produce supersymmetric Toda models, with superconformal symmetry being nonlinearly realized for those fields of the Toda system which are related to the bosonic simple roots of the superalgebra. A fermionic b-c system of conformal spin
is a natural ingredient of such models. 相似文献
134.
A stable mu-nitrido diiron phthalocyanine activates H2O2 to oxidize CH4 in water at 25-60 degrees C to methanol, formaldehyde and formic acid as evidenced using 13C and 18O labelling. 相似文献
135.
N.V. Loginova T.V. Koval’chuk N.P. Osipovich G.I. Polozov V.L. Sorokin A.A. Chernyavskaya O.I. Shadyro 《Polyhedron》2008
Co(II) complexes with 4,6-di(tert-butyl)-2-aminophenol (HLI) and 2-anilino-4,6-di(tert-butyl)phenol (HLII) have been synthesized and characterized by means of physico-chemical methods. The compounds HLI and HLII coordinate in their singly deprotonated forms and behave as bidentate O,N-coordinated ligands; their low-spin Co(II) complexes are characterized by CoN2O2 coordination modes and square planar geometry. Both the free ligands and their Co(II) and Cu(II) complexes (we have produced and characterized the latter before) exhibit a pronounced antifungal activity against Aspergillus niger, Fusarium spp., Mucor spp., Penicillium lividum, Botrytis cinerea, Alternaria alternata, Sclerotinia sclerotiorum, Monilia spp., which in a number of cases is comparable with that of Nystatin and Terbinafine or even higher. The reducing properties of the ligands and their metal(II) complexes, as well as their antifungal activities, were found to decrease in the order: Cu(LI)2 > Cu(LII)2 ? Co(LI)2 > Co(LII)2 > HLI > HLII. 相似文献
136.
A two-stage model of the capture of electrons and holes in traps in amorphous silicon nitride Si3N4 has been proposed. The electronic structure of a “Si–Si bond” intrinsic defect in Si3N4 has been calculated in the tight-binding approximation without fitting parameters. The properties of the Si–Si bond such as a giant cross section for capture of electrons and holes and a giant lifetime of trapped carriers have been explained. It has been shown that the Si–Si bond in the neutral state gives shallow levels near the bottom of the conduction band and the top of the valence band, which have a large cross section for capture. The capture of an electron or a hole on this bond is accompanied by the shift of shallow levels by 1.4–1.5 eV to the band gap owing to the polaron effect and a change in the localization region of valence electrons of atoms of the Si–Si bond. The calculations have been proposed with a new method for parameterizing the matrix elements of the tightbinding Hamiltonian taking into account a change in the localization region of valence electrons of an isolated atom incorporated into a solid. 相似文献
137.
P. P. Fedorov M. N. Mayakova S. V. Kuznetsov V. A. Maslov N. I. Sorokin A. E. Baranchikov V. K. Ivanov A. A. Pynenkov M. A. Uslamina K. N. Nishchev 《Russian Journal of Inorganic Chemistry》2016,61(11):1472-1478
The phase diagram of the NaF–CaF2 system was studied by thermal analysis and X-ray powder diffraction analysis with the determination of the chemical composition. The system was found to be of the eutectic type. A narrow range of the existence of solid solution Ca1–xNaxF2–x was established. The NaF solubility reaches a maximal value of x = 0.035 at 1200 ± 50°C (the temperature at which there is a diffuse phase transition in fluorite). At 920 ± 25°C, the NaF solubility reaches a minimum (<0.4 mol %) and increases again to 2.2 ± 0.2 mol % at a eutectic temperature (818°C). The ionic conductivity increases by three orders of magnitude after adding NaF to CaF2. 相似文献
138.
N. N. Vlasova M. S. Sorokin E. N. Oborina 《Russian Journal of Applied Chemistry》2016,89(7):1031-1042
Recently published data concerning the preparation and valuable properties of organosilicon compounds of silatrane structure with carbofunctional sulfur-containing substituents (thiol, sulfide, disulfide, polysulfide) and heteroatomic sulfur-containing groups (thiourea, thiourea dioxide, dithiocarbamate, thiuram disulfide) are summarized and analyzed. 相似文献
139.
N. I. Sorokin 《Crystallography Reports》2016,61(1):55-57
The ionic conductivity s of KYF4 and K2RF5 single crystals (R = Gd, Ho, Er) and KNdF4 and K2RF5 ceramic samples (R = Dy, Er) has been studied in the temperature range of 340–500°C. A comparative analysis of the σ values for these objects has been performed. Binary fluorides of potassium and rare earth elements were synthesized by the hydrothermal method (temperature 480°C, pressure 100–150 MPa) in the R2O3–KF–H2O systems. The σ values of tetraf luorides are 3 × 10–5 S/cm (KYF4 single crystal) and 3 × 10–6 S/cm (KNdF4 ceramics) at 435°C. A K2ErF5 single crystal with σ = 1.2 × 10–4 S/cm at 435°C has the maximum value of ionic conductivity among pentafluorides. The anisotropy of ionic transport was found in K2HoF5 single crystals, σ∥c/σ⊥c = 2.5, where σ∥c and σ⊥c are, respectively, the conductivities along the crystallographic c axis and in the perpendicular direction. 相似文献
140.
V. I. Anisimkin B. G. Pokusaev D. A. Skladnev V. V. Sorokin D. V. Tyupa 《Acoustical Physics》2016,62(6):754-759
Using acoustoelectronic sensors not containing sensitive coatings, we studied a series of microbiological preparations: yeast cells and bacteria, as well as virus particles, immobilized in hydrogels of different concentration. The obtained measurement data on the acoustic characteristics make it possible to (1) reveal the presence of biological objects in both fluid media and agarose-based hydrogels of various concentration; (2) establish the physical mechanism that results in acoustoelectronic detection; (3) evaluate changes in the concentration of biological objects and their electric conductivity. The data confirm the possibility of applying the acoustoelectronic technique to detect microbiological objects and observe their growth in hydrogel media. We discus the limitations and drawbacks of the acoustoelectronic technique. 相似文献