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51.
I. Ursu I. Apostol M. Dinescu I. N. Mihăilescu A. Popa A. M. Prokhorov V. I. Konov N. I. Chapliev 《Applied Physics A: Materials Science & Processing》1984,34(2):133-138
Progressive damage of aluminium mirrors subjected to microsecond pulsed TEA-CO2 laser irradiation in air, at incident intensity levels lower than the thresholds for melting induction and air breakdown ignition, was evidenced by electron microscopy investigations. A simple model was developed accounting for the results of our experimental studies. 相似文献
52.
Conclusions
From Stachys annua L. have been isolated the diacetate and two monoacetates of a new diterpenoid C20H32O3, which has been named stachysolone. It has been shown that stachysolone is a bicyclic ,-unsaturated ketone containing secondary and tertiary hydroxy groups.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 1, pp. 7–10, 1969 相似文献
53.
A microsecond periodic pulse was applied on thin probes in a positive column of a neon or helium glow discharge. The local transient phenomena provoked by this pulse were detected by a photomultiplier and presented in a time-distance display. They are qualitatively described and explained. The results are in good agreement with previous theories. 相似文献
54.
In this paper we consider two von Neumann subalgebras and of a type II1 factor . For a map φ on , we define
55.
We put forward a mechanism for tailoring, and even arresting, the collapse of wave packets in nonlinear media, whose dynamics is governed by nonlocal two-dimensional nonlinear Schr?dinger-like equations. The key ingredient of the scheme is the self-generation of nonlocal nonlinearities mediated by wave rectification. 相似文献
56.
A. P. Nizovtsev S. Ya. Kilin F. Jelezko I. Popa A. Gruber C. Tietz J. Wrachtrup 《Optics and Spectroscopy》2003,94(6):848-858
The spin-selective photokinetics of a single matrix-isolated impurity molecule with a triplet-triplet optical transition, T 0–T 1, is considered and the manifestations of the photokinetics in the fluorescence excitation spectra and intensity autocorrelation functions g (2)(τ) of the molecule undergoing narrow-band optical excitation is studied to resolve the fine structure of the transition. The rates of intersystem crossings (ISCs) T 1→S→T 0 to and from a nonradiating singlet state S of the molecule and the rate of population relaxation among the ground (T 0) state sublevels can be obtained from the spectra and g (2)(τ) using the analytical expressions obtained. New experiments on an individual NV defect center in nanocrystals of diamond, where, for the first time, the fine structure of its triplet-triplet 3 A-3 E zero-phonon optical transition (~637 nm) at 1.4 K was resolved, are interpreted. It is concluded that the rate of the ISC transition from the m S =0 sublevel of the excited 3 E state to the singlet 1 A state (~1 kHz) is much slower than the rates from the m S =±1 substates, while the rates of ISC transitions to different m S substates of the ground 3 A state are close to each other (~1 Hz). As a result, only the optical transition between m S =0 sublevels in the 3 A-3 E manifold contributes strongly to the fluorescence. The experimentally observed double-exponential decay of the g (2)(τ) function is explained by the two pathways available to the center for it to leave the S state: (i) the S→ T 0(m S )=0) transition and (ii) the S→T 0(m S =±1) transitions followed by the slow spin-lattice relaxation T 0(m S =±1)→T 0(m S =0) (rate ~0.1 Hz). The work is important for studies where the NV center is used as a single photon source or for quantum information processing. 相似文献
57.
Dumitru Vălcan 《Czechoslovak Mathematical Journal》2003,53(2):277-287
The present work gives some characterizations of R-modules with the direct summand sum property (in short DSSP), that is of those R-modules for which the sum of any two direct summands, so the submodule generated by their union, is a direct summand, too. General results and results concerning certain classes of R-modules (injective or projective) with this property, over several rings, are presented. 相似文献
58.
Zinc selenide (ZnSe) thin films (d = 0.11-0.93 μm) were deposited onto glass substrates by the quasi-closed volume technique under vacuum. Their structural characteristics were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). The experiments showed that the films are polycrystalline and have a zinc blende (cubic) structure. The film crystallites are preferentially oriented with the (1 1 1) planes parallel to the substrate surface. AFM images showed that the films have a grain like surface morphology. The average roughness, Ra = 3.3-6.4 nm, and the root mean square roughness, Rrms = 5.4-11.9 nm, were calculated and found to depend on the film thickness and post-deposition heat treatment.The spectral dependence of the absorption coefficient was determined from transmission spectra, in the range 300-1400 nm.The values of optical bandgap were calculated from the absorption spectra, Eg = 2.6-2.7 eV.The effect of the deposition conditions and post-deposition heat treatment on the structural and optical characteristics was investigated. 相似文献
59.
60.
We describe a simple method for tracking the course of microbial degradation of polysaccharide-rich feedstocks. The method
involves determining total polysaccharides present in the feedstock, measured in glucose equivalents, relative to the fractional
component of polysaccharides exhibiting 2,3-dinitrosalycylic acid aldehyde activity. The ratio of total polysaccharide to
aldehyde activity, defined as the end-point fragmentation (EPF) index, is then calculated and tracked as it shifts as microbial
degradation of polysaccharide-rich feedstock progresses. While degradation occurs, the EPF index falls. It bottoms out at
an asymptotic limit marking the point in time where further degradation of the polysaccharide-rich feedstock has ceased. The
EPF index can be used to follow the progressive breakdown of composting polysaccharide-rich waste. It may also have applicability
as a means of tracking the turnover of polysaccharides in other complex environments including soil, sediments, wetlands,
and peat bogs. 相似文献