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991.
Mechanical models of rocks subjected to various bulk stress states are considered. The models contain the Nadai parameter, which takes into account various types of the bulk stress state, the potential energy of bulk variation, and the potential energy of variations in the shape of rock elements in the equilibrium stress-strain state. These variables permit determining the conditions under which rock massifs stay in equilibrium and the conditions under which rock can cease to be in equilibrium owing to the bulk stress state action; they also allow one to justify the physical parameters of the rock strength certificate under the bulk stress state action and determine the constraint equation relating the stress and strain invariants for inhomogeneous rocks. 相似文献
992.
Sergey A. Danilkin 《Solid State Ionics》2009,180(6-8):483-487
The energy-resolved neutron diffraction and inelastic neutron scattering study of diffuse scattering in copper chalcogenides was performed in order to clarify the role of static disorder versus low-energy phonons. Neutron diffraction patterns taken from Cu1.75Se, Cu1.98Se and Ag0.25Cu1.75Se powders in superionic phase show a broad maximum related to diffuse scattering. This diffuse background is suppressed in the energy-resolved experiment which indicates a strong contribution from inelastic scattering coming from correlated thermal displacements of the ions in the superionic phase. Diffraction experiments on a single crystal of α-Cu1.8Se have revealed an ordered structure with superstructure reflections at the G ± 1/2 <111> and G ± 1/3 <220> positions of reciprocal space at room temperature. In addition to superstructure spots, diffuse scattering was observed along the <111> direction which is considered as a possible diffusion path of mobile Cu ions. In inelastic neutron scattering measurements with this single crystal sample strong inelastic scattering was observed along <111>. This shows that the diffuse scattering found in conventional diffraction experiment is mainly inelastic and most probably comes from low-energy phonons. 相似文献
993.
We discuss the early history of an important field of “sturm and drang” in modern theory of nonlinear waves. It is demonstrated how scientific demand resulted in independent and almost simultaneous publications by many different authors on modulation instability, a phenomenon resulting in a variety of nonlinear processes such as envelope solitons, envelope shocks, freak waves, etc. Examples from water wave hydrodynamics, electrodynamics, nonlinear optics, and convection theory are given. 相似文献
994.
Polycapillary‐optics‐based micro‐XANES and micro‐EXAFS at a third‐generation bending‐magnet beamline
Geert Silversmit Bart Vekemans Sergey Nikitenko Wim Bras Viktoria Czhech Gyula Zaray Imre Szaloki Laszlo Vincze 《Journal of synchrotron radiation》2009,16(2):237-246
A focusing system based on a polycapillary half‐lens optic has been successfully tested for transmission and fluorescence µ‐X‐ray absorption spectroscopy at a third‐generation bending‐magnet beamline equipped with a non‐fixed‐exit Si(111) monochromator. The vertical positional variations of the X‐ray beam owing to the use of a non‐fixed‐exit monochromator were shown to pose only a limited problem by using the polycapillary optic. The expected height variation for an EXAFS scan around the Fe K‐edge is approximately 200 µm on the lens input side and this was reduced to ~1 µm for the focused beam. Beam sizes (FWHM) of 12–16 µm, transmission efficiencies of 25–45% and intensity gain factors, compared with the non‐focused beam, of about 2000 were obtained in the 7–14 keV energy range for an incoming beam of 0.5 × 2 mm (vertical × horizontal). As a practical application, an As K‐edge µ‐XANES study of cucumber root and hypocotyl was performed to determine the As oxidation state in the different plant parts and to identify a possible metabolic conversion by the plant. 相似文献
995.
The electrochemical reduction of nitric oxide in the presence of the excess oxygen was reviewed. It was shown that the selectivity
and activity of the cathodes is strongly dependent on the composition and on the microstructure of the cathode material. A
concept of electrochemical reactor with multilayer electro-catalytic electrode was proposed and successfully designed in Advanced
Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya, Japan.
The typical values of current efficiency in such electrochemical reactors are of the order of 10–20% at gas composition: 1,000 ppm
NO and 2% O2 balanced in He and at gas flow rate 50 ml/min. The value of current efficiency depends on the functional multi-layer electrode
composition, structure, and operating temperature. Such electrochemical reactors show the value of NO/O2 selectivity (ν
sel) higher than 5 (ν
sel > 5) at intermediate temperature and up to ν
sel = 25 at low temperature operation. It was shown that multilayer electro-catalytic electrode should consist at list from three
main functional layers: cathode, electro-catalytic electrode, covering layer, in order to operate as an electrode with high
selectivity. 相似文献
996.
Phase transformations of 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane: the role played by water, dislocations, and density 总被引:1,自引:0,他引:1
N. V. Chukanov V. A. Dubovitskii V. V. Zakharov N. I. Golovina B. L. Korsunskii S. A. Vozchikova V. V. Nedel’ko T. S. Larikova A. V. Raevskii S. M. Aldoshin 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(3):486-493
A comparative study of the kinetics and mechanisms of the α → γ and ? → γ polymorphic transitions in polycrystalline haxanitrohexaazaisowurtzitane was performed using electron and optical microscopy, calorimetry, IR spectroscopy, and quantitative X-ray phase analysis. The kinetics of both processes is complex because of the morphology of the crystals, their defect structure, and impurities. As distinct from the ? → γ process, which always occurs as a single crystal-polycrystal transition (through nucleation by the dislocation mechanism with subsequent movement of the phase separation front), the α → γ process can also follow the quasi-homogeneous mechanism and occur as a single crystal-single crystal transition. 相似文献
997.
V. P. Zakharov O. N. Makurina E. V. Timchenko P. E. Timchenko S. P. Kotova R. V. Valliylov 《Laser Physics》2009,19(6):1366-1372
The application of the differential backscattering method and the fluorescent analysis of wood cultures for the determination of ecological quality of different megapolis areas are investigated. The correlation of leaves optical characteristics with the data of the chemical analysis of leaves pigments concentration is shown on the basis of the year statistical results of wood cultures spectral characteristics observation. It is experimentally found that the method of differential backscattering allows to identify megapolis areas on their ecological level. 相似文献
998.
A. V. Semirov D. A. Bukreev V. O. Kudryavtsev A. A. Moiseev A. A. Gavrilyuk A. L. Semenov G. V. Zakharov 《Technical Physics》2009,54(11):1586-1590
The effect of temperature and elastic tensile stresses on the magnetoimpedance of an amorphous Vitrovac 6025Z (Fe4CO67Mo1.5Si16.5B11) foil is studied. Two temperature ranges (20–70 and 70–220°C) in which the effect of elastic tensile stresses on the magnetoimpedance
has different characters are detected. The existence of these two temperature ranges is shown to be caused by a change in
the sign of a magnetostriction constant at 70°C. 相似文献
999.
M. B. Tsetlin A. A. Zakharov K. I. Maslakov M. N. Mikheeva I. Lindau 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(5):752-755
The process of an ultrahigh vacuum annealing of a diamond-like carbon film deposited on a silicon substrate has been studied
in situ using a photoemission microscope mounted at the MAX-lab synchrotron’s radiation source. After the annealing the film
was examined ex situ using an atomic force microscope. It is revealed that the graphitization of the film occurs and round
formations of several microns in size with a core of ∼0.2 μm in size appear on its surface at the temperature exceeding 1000°C.
Photoemission images of these formations have shown the presence of silicon on their surface. Apparently, the interaction
between the carbon film and silicon substrate begins in the middle of the formation and spreads to the adjacent region at
the following stage. 相似文献
1000.
V. I. Strelov B. G. Zakharov V. K. Artemiev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(1):98-104
The influence of gravitation vector orientation relative to the solidification front on the dopant distribution micro- and macrohomogeneity in vertical oriented crystallization of highly Ga-doped Ge crystals has been investigated using computer simulation. The deviation of the axis for crystal growth relative to the g 0 vector, when a free surface of the melt is present, has been found to provide the formation of striations with a reduced dopant concentration. The influence of the solidification rate, convective and diffusion mass flows on the dopant distribution macrohomogeneity has been investigated. 相似文献