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排序方式: 共有86条查询结果,搜索用时 78 毫秒
1.
Z. A. Samoilenko V. D. Okunev E. I. Pushenko T. A. D’yachenko A. Cherenkov P. Gierlowski S. J. Lewandowski A. Abal’oshev A. Klimov A. Szewczyk 《Technical Physics》2003,48(2):250-256
Crystallographic phase transitions in perovskite-like LaSrMnO metallic oxides are studied. The transitions are induced when
internal stresses generated during film synthesis (at temperatures between 450 and 730°C) vary (decrease or increase) upon
subsequent irradiation by a KrF laser emitting in the UV range. As the synthesis temperature T
s grows, the rhombohedral-to-orthorhombic phase transition occurs at 650–670°C. The resistivity is shown to be either temperature-independent,
ρ(T)=const, at T<T
crit, or varies and reaches a maximum, ρ(T)=ρmax, at the Curie temperature T
c. Optical transmission spectra taken at photon energies ℏω=0.5–2.5 eV exhibit both a high (0.8–0.9) and low (0.1–0.3) transmission
coefficient t, depending on the synthesis temperature. As follows from X-ray diffraction data, the laser irradiation causes a phase transition
only in LaSrMnO films grown at T
s<650°C. Phases of different size scales appear: the long-range-order orthorhombic matrix and mesoscopic-range-order rhombohedral
clusters are observed in the films grown at T
s=450–550°C and the rhombohedral matrix with orthorhombic clusters, in the films grown at T
s=550–650°C. 相似文献
2.
Okunev A. G. Sharonov V. E. Gubar" A. V. Danilova I. G. Paukshtis E. A. Moroz E. M. Kriger T. A. Malakhov V. V. Aristov Yu. I. 《Russian Chemical Bulletin》2003,52(2):359-363
Sorption of CO2 in the presence of water vapor by the K2CO3—-Al2O3 composite sorbent was studied by IR spectroscopy in situ, X-ray diffraction analysis, and the differentiating dissolution method and reasons for a decrease in its dynamic capacity are given. The samples containing K2CO3·1.5H2O in pores are characterized by the maximal dynamic capacity. A mechanism for CO2 sorption was proposed, which qualitatively explains the obtained dependence of the capacity on the water content in the composite sorbent. A high dynamic capacity can be maintained by regeneration of the sorbents by water vapor at 170 °N. The capacity of the sorbents decreases during the first 10 sorption—regeneration cycles due to the formation of an inactive phase of potassium aluminum carbonate. 相似文献
3.
Alexander V. Gusakov Arkady P. Sinitsyn Alejandro G. Berlin Nonna N. Popova Alexander V. Markov Oleg N. Okunev Dmitry F. Tikhomirov Mark Emalfarb 《Applied biochemistry and biotechnology》1998,75(2-3):279-293
A model microassay system was developed to measure indigo backstaining on cotton fabrics in the presence of enzymes on a small
laboratory scale. Backstaining indexes for 11 cellulase samples were measured, and the enzymes were ranked from lower to higher
backstaining. Two multienzyme cellulase preparations were separated into fractions using chromatofocusing on a Mono P column.
Adsorption ability and backstaining properties of purified enzyme fractions were studied. Evidence was obtained that protein
adsorption on cotton fabrics is a crucial parameter causing backstaining (both for crude cellulase samples and purified enzyme
components). 相似文献
4.
Alex Berlin Neil Gilkes Douglas Kilburn Vera Maximenko Renata Bura Alexander Markov Anton Skomarovsky Alexander Gusakov Arkady Sinitsyn Oleg Okunev Irina Solovieva John N. Saddler 《Applied biochemistry and biotechnology》2006,130(1-3):528-545
Seven cellulase preparations from Penicillium and Trichoderma spp. were evaluated for their ability to hydrolyze the cellulose fraction of hardwoods (yellow poplar and red maple) pretreated by organosolv extraction, as well as model cellulosic substrates such as filter paper. There was no significant correlation among hydrolytic performance on pretreated hardwood, based on glucose release, and filter paper activity. However, performance on pretreated hardwood showed significant correlations to the levels of endogenous β-glucosidase and xylanase activities in the cellulase preparation. Accordingly, differences in performance were reduced or eliminated following supplementation with a crude β-glucosidase preparation containing both activities. These results complement a previous investigation using softwoods pretreated by either organosolv extraction or steam explosion. Cellulase preparations that performed best on hardwood also showed superior performance on the softwood substrates. 相似文献
5.
V. G. Nikolenko I. S. Okunev S. S. Parzhitskii Yu. P. Popov Yu. M. Chuvil’skii 《Physics of Particles and Nuclei Letters》2007,4(1):22-28
A three-vector a pt (σ n [k α × s γ]) correlation of the neutron beam polarization directions σ n , α-particle momentum k α, and γ-quantum circular polarizations s γ in 10B(n, α1γ)7Li reaction (E γ = 478 keV) is proposed as a means of searching for the simultaneous time-reversal invariance and space parity (PT-invariance) violation. An expression for a pt coefficient in the αγ cascade is presented. Masking effects, sensitivity of the proposed experiment, and its realization prospects are discussed. 相似文献
6.
7.
Electron paramagnetic resonance was used to study the dependence of the volume spin density of dangling bonds ina-Ge films produced by cathode sputtering in argon on annealing temperature. The structure of the films is determined by x-ray diffraction analysis. Two EPR lines with g=2.019 and g=2.003 are observed whose intensities change nonmonotonically with annealing temperature. The g=2.019 line is characteristic only of the amorphous state of germanium, while the g=2.003 line persists even after crystallization of the films. When the results are compared with structure data, the conclusion may be drawn that the observed lines in the EPR spectrum are related to the dangling bonds in the peripheral regions of two types of clusters. The g=2.003 line is due to dangling bonds in the peripheral region of clusters with the usual cubic packing of atoms, and the g=2.019 line is due to clusters of the hexagonal type, which is not characteristic of the normal structure of crystalline germanium.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 51–57, July, 1989. 相似文献
8.
Okunev VD Samoilenko ZA Szewczyk A Szymczak R Szymczak H Lewandowski SJ Aleshkevych P Wi?ckowski J Khmelevskaya VS Antoshina IA 《J Phys Condens Matter》2011,23(41):415702
We have reinforced local superconductivity in ferromagnetic Fe(67)Cr(18)B(15) metallic glasses by ion irradiation. Superconductivity in this medium appears due to the presence of large-scale layered clusters of metallic Fe-Cr phase, 150-230 ? in size, with a ferromagnetic (or superparamagnetic) Fe-rich core and nonmagnetic Cr-rich superconducting shell. Here we show that due to the intensification of concentration phase separation in the Fe-Cr clusters under ion (Ar(+)) irradiation, the volume of the superconducting phase increases from the initial 0.4-0.5% up to 7-8%. After irradiation, the resistivity jump Δρ/ρ in the temperature range T=3.1-3.6 K increases ~14 times, reaching 19%, as compared to 1.36% for the initial sample. In the interval of T=3.1-3.6 K, the rate of resistance change reaches 79% K(-1) for the irradiated sample instead of 3.6% K(-1) for the initial sample. In the same temperature interval, the rate of magnetoresistance change increases from 3% K(-1) for the initial sample up to 70% K(-1) after irradiation. 相似文献
9.
V. D. Okunev N. N. Pafomov V. A. Isaev T. A. D’yachenko A. Klimov S. J. Lewandowski 《Physics of the Solid State》2002,44(1):157-161
This paper reports on new results of experimental investigations into the nature of the electrical resistivity ρ(T) ? const at T<T crit for YBaCuO and LaSrMnO dielectric films. The films are prepared by pulsed laser deposition and contain nanocrystalline clusters with metallic conductivity. Dependences of the electrical resistivity ρ(T) ? const are observed for the epitaxial films YBaCuO (T crit=10 K) with a tetragonal structure after exposure to KrF excimer laser radiation and for the as-prepared amorphous films LaSrMnO (T crit?160 K). The effect of interest (ρ(T) ? const) manifests itself in the case when the optical spectra of the studied samples contain portions attributed to absorption by free charge carriers. The inference is made that this effect can be associated with tunneling conduction in a system of quantum dots. 相似文献
10.
Oleg Okunev 《Topology and its Applications》2011,158(16):2158-2164
We prove that if X and Y are t-equivalent spaces (that is, if Cp(X) and Cp(Y) are homeomorphic), then there are spaces Zn, locally closed subspaces Bn of Zn, and locally closed subspaces Yn of Y, n∈N+, such that each Zn admits a perfect finite-to-one mapping onto a closed subspace of Xn, Yn is an image under a perfect mapping of Bn, and Y=?{Yn:n∈N+}. It is deduced that some classes of spaces, which for metric spaces coincide with absolute Borelian classes, are preserved by t-equivalence. Also some limitations on the complexity of spaces t-equivalent to “nice” spaces are obtained. 相似文献