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991.
V. S. Pavlovich A. P. Stupak L. G. Pikulik D. T. Kozhich T. A. Pavich 《Journal of Applied Spectroscopy》2008,75(3):319-324
The molar extinction coefficient, oscillator strength, natural fluorescence lifetime, and fluorescence quantum yield have
been determined for 9,10-diiodoanthracene in ethanol at 20°C. The temperature effect on the quantum yield was studied in the
range 120–300 K. The fluorescence lifetime was measured at 77 K. During glassification of ethanol, the fluorescence intensity
of 9,10-diiodoanthracene increases by more than 50 times due to the activation nature of the intersystem crossing from the
S1(1B2u+) state. The activation energy and pre-exponential factor for the probability of the intersystem {ie319-01}-crossing are found.
The long-wavelength shift of the absorption spectrum with increasing bulk polarizability of the solvent is interpreted as
evidence of changes in the nonspecific interactions.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 304–308, May–June, 2008. 相似文献
992.
S. F. Baranovskii P. A. Bolotin M. P. Evstigneev D. N. Chernyshev 《Journal of Applied Spectroscopy》2008,75(2):251-260
We have used spectrophotometry to study self-association and complexation with DNA by organic heterocyclic compounds in the
acridine and phenothiazine series: proflavin, thionine, and methylene blue. Based on the experimental concentration dependences
of the molar absorption coefficient of the molecules in an aqueous buffer solution (0.01 M NaCl, 0.01 M Na2EDTA, 0.01 M Tris, pH 7.4, T = 298 K), we have determined the equilibrium dimerization constants for the dyes and the DNA
complexation parameters using the Scatchard and McGhee-von Hippel models. The observed increase in the cooperativity parameters
as the dimerization constants of the ligands increase allowed us to hypothesize that the same interactions occur between dye
molecules adsorbed on DNA as in their self-association. The equilibrium DNA-binding constants for the ligands, obtained using
the McGhee-von Hippel cooperative model, are (20.9 ± 2.7)·103 M−1 for proflavin and (33.8 ± 4.1)·103 M−1 for thionine. Using the Scatchard model, taking into account intercalation and “external” binding of ligands with DNA, we
determined the DNA complexation constants for methylene blue: (26.4 ± 4.6)·103 and (96 ± 17)·103 M−1 respectively. Based on analysis of the data obtained, we hypothesized that the predominant type of binding with DNA is intercalation
binding in the case of proflavin and thionine, and “external” binding with the DNA surface in the case of methylene blue.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 242–249, March–April, 2008. 相似文献
993.
V.A. Chernenko A. Fujita S. Besseghini J.I. Prez-Landazabal 《Journal of magnetism and magnetic materials》2008,320(14):e156-e159
Results of the low-temperature specific heat measurements (2–80 K) for one austenitic and three martensitic Ni–Mn–Ga ferromagnetic alloys are presented. The alloy compositions are chosen to comprise a wide span of valence electron concentrations e/a=7.3–7.78. Debye temperature (261–345 K) is found to be an increasing function of e/a while the experimental values of the Sommerfeld coefficient (2.9–3.4 mJ/mol K2) appear to be increasing in the martensitic region only. Observation of those trends rekindles the discussion about the role of vibrational and electronic contributions to the lattice instability and transformation mechanism of studied alloys. 相似文献
994.
We show that the fluctuations of the tick-by-tick logarithmic price in a futures market can be described in terms of the Fokker-Planck equation (FPE). We calculate the corresponding drift and diffusion coefficients and argue that these values can contain some information pertaining to the market state. It is particularly showed that the Korean treasury bond (KTB) futures is well described by a FPE and has a similar structure to turbulence. 相似文献
995.
Thomas C. Amu 《Journal of solution chemistry》1981,10(1):69-78
Interdiffusion coefficient have been measured for 1,1,2,2-tetrabromoethane in 21 organic solvents in order to ascertain the influence of shape, size, viscosity, nature and degree of branching, of the solvent molecules on transport properties. None of the existing correlations for diffusion in binary liquid systems appear to fit all the experimental data. Steric effects due to the solvent molecules are shown to be very important in the interpretation of the diffusion process. 相似文献
996.
基于Fluent软件平台,采用数值模拟方法对非稳态圆柱体结构尾流流动特性进行了研究。对在Re=50~200范围内,双旋转附属圆柱的转速对主圆柱体尾流流动特性的影响进行了分析。研究结果表明:随着附属圆柱旋转速率的增加,主圆柱体表面所受阻力系数平均值与均方根值、升力系数均方根值均会减小。同时,旋转速率的变化对柱体结构表面压力分布的影响显著,压力系数在附属圆柱的位置产生了跳跃性变化。另外,当附属圆柱转速达到临界值时,尾流涡街变窄,涡脱落现象消失,并且系统的能量效率到达最佳状态。 相似文献
997.
998.
A compartmental model is developed to estimate flow parameters of a shallow aquifer affected by water loads in surface reservoirs and to evaluate its nonsteady flow distribution. The method incorporates temporal piezometric head measurements and sampling of water for dissolved chemicals and isotopes analyses. Each compartment is governed by a set of equations describing the conservation of linear momentum and mass balance expressions for water, isotopes, and dissolved chemicals. The number of compartmental balance expressions always must be greater than that of the unknown flow parameters associated with each compartment. An optimization method is described to yield spatial distribution of aquifer storativity, transmissivity, porosity, leakage, and compliance coefficients and fluxes leaking into an aquifer's lower boundary. Future predictions of an aquifer's piezometric head distribution in a compartmental system is formulated on the basis of the estimated flow parameters and the leakage components.Compartmental modelling which incorporates concentrations of environmental tracers, may yield efficiency in computing resources and accuracy enhancement for predicting an aquifer's flow regime. 相似文献
999.
M. Yanuka 《Transport in Porous Media》1992,7(3):265-282
The percolation theory approach to static and dynamic properties of the single- and two-phase fluid flow in porous media is described. Using percolation cluster scaling laws, one can obtain functional relations between the saturation fraction of a given phase and the capillary pressure, the relative permeability, and the dispersion coefficient, in drainage and imbibition processes. In addition, the scale dependency of the transport coefficient is shown to be an outcome of the fractal nature of pore space and of the random flow pattern of the fluids or contaminant. 相似文献
1000.
In this paper, Lorentz forces are proved to be able to suppress separation in flows over hydrofoils. Furthermore, a differential equation of pressure distributions on the hydrofoil surface is derived, from which it is found that BVF (boundary vortex flux) σ is a suitable criterion for describing the lift coefficient variations during the electromagnetic control process. According to our numerical results, the periodic variations of lift for a hydrofoil at an attack angle of 17 ° are analyzed and its inherent mechanism is discussed in detail with the concept of BVE On the other hand, the effects of Lorentz force on the hydrofoil's lift are investigated both experimentally and numerically for different magnitudes and locations. 相似文献