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11.
The effect of short-term low-temperature annealing in air and in vacuum on the properties of HTSC films of YBCO is studied. It is shown that, under certain conditions of preparation of initial samples, a transition from the HTSC phase with the superconducting transition temperature Tc=90 K to a phase with Tc=60 K occurs without a noticeable change in the oxygen content. It is found that, as a result of short-term annealings, a transition from the HTSC phase with Tc=60 K to the phase with Tc=90 K can occur only through the vacuum annealing stage, which converts the sample into the superconducting state. Short-term annealings lead to multiple reversible “switching” of the films from one phase to another. The obtained results are of practical interest, since the proposed method can be used to quickly obtain superconducting YBCO films in various phase states. It is shown, in addition, that the annealing procedure makes it possible not only to increase the oxygen concentration but also to produce a structural rearrangement of a YBCO film. 相似文献
12.
The response to drying and storage at -20 degrees C or in liquid nitrogen was studied in seeds of the freshwater aquatic plant Najas flexilis. The seeds of this species show some desiccation sensitivity, although post-harvest storage in water at 16 degrees C resulted in improvements in desiccation tolerance. There was 63% germination of seeds dried to 9.5% moisture content (30% RH) following this maturation period. Optimum moisture contents for seeds stored at -20 degrees C for 3 months and in liquid nitrogen for 1 week were ~11% and ~15%, respectively. 相似文献
13.
LI GuangShun ZHOU XiaoHong ZHANG ShuangQuan ZHANG YuHu & MENG Jie Institute of Modern Physics Chinese Academy of Sciences Lanzhou China Graduate University of Chinese Academy of Sciences Beijing School of Physics SK Laboratory of Nuclear Physics & Technology Peking University Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(Z1)
Theoretical calculations have been performed for the ν9/2+[624](i13/2) and ν7/2-[503](f7/2) bands of 185Pt in the framework of particle-rotor model. The band properties of signature splitting and configuration mixing have been analyzed. The level energy and signature splitting before the band crossing can be well interpreted by introducing triaxiality. The positive-parity yrast band is pro posed to be dominated by the ν9/2+[624](i13/2) component, while the negative-parity band shows strong mixing of ν7/2-[5... 相似文献
14.
We have examined the process of redox dispersion of silver, using a solution simultaneously containing an oxidizing agent
(potassium ferricyanide) and a reducing agent (sodium borohydride). We have studied the changes over time in the Raman spectra
of the indicated solution when no silver particles are present and when such particles are added to the solution. We have
established that the silver particles have a catalytic effect on the reaction between potassium ferricyanide and sodium borohydride,
kinetically slowed down in alkaline medium. The original silver particles (1–20 μm) undergo redox dispersion as a result,
and Ag particles are formed with sizes 1–10 nm.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 182–186, March–April, 2006. 相似文献
15.
S.Ya. Rakhmanov 《Solid State Communications》1979,30(12):779-782
The possibility of existance of a super-crystalline (Wigner) phase in a semimetal or impurity semiconductor film placed in a high magnetic field, is discussed and a comparison is made with a crystal in a three-dimensional specimen.
Such a phase exists in a succession of magnetic field or particle density intervals. The vibrational spectrum depends on magnetic field, while the bind energy is only density-dependent. The mean-square displacement x2 of the particles in the lattice sites are also independent on the magnetic field over a wide temperature range. 相似文献
16.
The formation of droplets (or breathers) of vortex matter in Bi(2)Sr(2)CaCu(2)O(8) crystals pumped by the low-frequency ac magnetic field is observed by magneto-optic imaging. The droplets nucleate at the points of crossing the planar defects. The magnetic flux in the droplet and the droplet size increase with time. When the flux in the droplet exceeds a critical value, the droplet shifts along the defect to the sample bulk and a new droplet with the opposite flux direction starts to nucleate at the same point. As a result, a beadlike structure of the droplets arises along the defect. A possible explanation of the phenomenon is proposed. 相似文献
17.
G. T. Mavlonov Kh. A. Ubaidullaeva M. I. Rakhmanov I. Yu. Abdurakhmonov A. Abdukarimov 《Chemistry of Natural Compounds》2008,44(2):216-219
A low-molecular-weight protein with antifungal activity was isolated from freshly collected latex of the Inzhir tree (Ficus carica L.) by successive affinity chromatography over chitin, cation-exchange chromatography over SP-Sephadex C-50, and reversed-phase
HPLC. The molecular weight of 6481 and the partial N-terminus sequence of the protein were determined (MALDI-TOFMS).
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 171–173, March–April, 2008. 相似文献
18.
A model to describe the effect of torsional stresses on the magnetoimpedance of amorphous wires with negative magnetostriction
is suggested. An approximate expression for the impedance with regard to the spatial distribution of magnetoelastic anisotropy
induced by torsional stresses is derived. It is shown that the relative variation of the impedance is maximal near a critical
stress value at which the surface magnetic structure of the wire changes. The calculated dependences of the impedance on the
external magnetic field and torsional stress are in good qualitative agreement with experimental data for amorphous wires
with negative magnetostriction. 相似文献
19.
A. Sboychakov A. Rakhmanov K. Kugel I. González J. Castro D. Baldomir 《Journal of magnetism and magnetic materials》2006
The behavior of a one-dimensional antiferromagnetic (AF) chain doped by non-magnetic donor impurities is analyzed, in the limit of low impurity density n . The doping leads to the formation of ferromagnetically correlated regions localized near impurities (bound magnetic polarons or ferrons). The temperature evolution of the chain is calculated using an approximate variational method, and a Monte Carlo simulation. Both these methods give the similar results. The analysis of correlation functions for neighboring local spins demonstrates that the ferromagnetic correlations inside a ferron are significant even at high temperatures. The AF correlations in the rest part of the chain decay much faster with temperature. So, the ferron is a stable object that does not disappear even above the Néel temperature TN. At rather small values of the electron–impurity coupling energy V (for V lower then the electron hopping integral t ), the bound ferron depins from impurity retaining its magnetic structure. Such a depinning occurs at T∼V. 相似文献
20.
In this paper an alternative approach for measurement of στ product for 4
F
3/2→4
I
11/2 transition of Nd3+ doped YVO4 crystal is reported. In this method a microchip laser is formed by keeping a small piece of the sample in plane-plane resonator
and a diode laser (808 nm) is used for pumping. The pump power induced thermal lensing effect is used to make the cavity stable.
The cavity mode area is estimated by measuring the thermal lens focal length at the threshold and the average pump area is
measured by Gaussian fit to the intensity profiles of the pump beam. The value of στ product of Nd:YVO4 crystal obtained by this method is within 10% of the reported values. The advantage of this method is that it is a simple
method for direct measurement of στ product of laser crystals. 相似文献