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101.
D.R. Symes J. Osterhoff R. Fustlin M. Maurer A.C. Bernstein A.S. Moore E.T. Gumbrell A.D. Edens R.A. Smith T. Ditmire 《High Energy Density Physics》2007,3(3-4):353-357
To study hydrodynamic behavior on thin shell high Mach number blast waves, experiments have been performed in which spatially tailored shock waves have been launched in a gas of clusters using an intense 35 fs laser pulse. The target medium was first modified by destroying clusters in specific locations using a spatially modulated laser focus. Under subsequent intense laser irradiation, the efficient absorption properties of the remaining clustered regions compared to those regions with no clusters led to a pattern of hot and cold plasma resulting in a cylindrical blast wave with a periodic modulation imprinted on the shock front. This technique may provide a method for studying thin shell instabilities in strongly radiative blast waves. 相似文献
102.
The equations of motion are set up for a simple rotor (Jeffcott or Laval rotor) on a rigid foundation mass resting on an elastic half space (soil). The unbalance response and the stability limit against self-excited vibrations caused by the internal damping of the rotating shaft are calculated. The numerical results presented as response diagrams and stability graphs show that the damping effect of the soil on the system, due to radiation of energy, may have a very positive influence on the smooth running of the rotors. 相似文献
103.
B. Jimenez C. Alemany J. Mendiola E. Maurer 《Journal of Physics and Chemistry of Solids》1985,46(12):1383-1386
The ferro-paraelectric transition in Sr0.5Ba0.5Nb2O6 ceramics has been studied by measuring the dielectric pennitivity as a function of temperature at different frequencies. Experimental results in the transition region over ?'max fit the relation with γ > 1, as is typical for dif transitions. In an interval of temperatures of 17°C over T0 (=Tfor?'max), γ = 2. Using the relaxors' model of Kirillov-Isupov an equation is inferred in order to compute the activation energy of the relaxors as a function of parameters directly obtained from the experimental results. 相似文献
104.
Based on holographic interferometry data for electrophoresis and diffusion, an algorithm for quantitatively analyzing protein mass transfer in gels is suggested and implemented. The diffusion coefficients of a number of proteins in different media are found. 相似文献
105.
D. K-H. Finkler T. Heck A. E. Maurer S. J. Campbell U. Gonser 《Hyperfine Interactions》1988,41(1):571-574
TheCuAuFe system has been studied by room temperature Mössbauer spectroscopy in order to examine the influence of varying both iron (Cu94?yAu6Fey; y=0.2–1.0 at%) and gold (Cu99?xAuxFe1; x=6–50.7 at%) concentrations on the clustering of iron atoms. Samples were examined in different metallurgical states, as rolled, fast quenched and melt spun with similar degrees of clustering being observed. The isomer shift is found to vary inversely with atomic volume for the Cu99?xAuxFe1 alloys. 相似文献
106.
Studies are described on the metabolism and toxicological analysis of the phenethylamine-derived designer drug 2,5-dimethoxy-4-propylthio-beta-phenethylamine (2C-T-7) in rat urine using gas chromatography/mass spectrometry (GC/MS). The identified metabolites indicated that 2C-T-7 was metabolized by hydroxylation of the propyl side chain followed by N-acetylation and sulfoxidation and also by deamination followed by oxidation to the corresponding acid or by reduction to the corresponding alcohol. To a minor extent, 2C-T-7 was also metabolized by S-dealkylation followed by N-acetylation, S-methylation and sulfoxidation. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction microwave-assisted acetylation allowed the detection of an intake of a dose of 2C-T-7 in rat urine that corresponds to a common drug users' dose. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of 2C-T-7 in human urine. 相似文献
107.
Temperature-gradient gel electrophoresis (TGGE) is a technique for studying the structural transitions of nucleic acids and proteins. A temperature gradient is formed in a horizontal slab gel perpendicular to the direction of the electric field. Whereas the principle of the TGGE method has previously been applied to proteins, we describe in this report the systematic optimization of TGGE as a routine technique for the quantitative analysis of conformational transitions in proteins. Using alpha-amylase as an example we show the kinds of results which may be obtained from such measurements. Buffers suitable for use in gel electrophoresis were analyzed with respect to the dependence of their pH value upon temperature. The correct pH range for TGGE of a given protein is determined by electrophoretic titration curves. The protein bands are detected by silver and/or activity staining. The thermal denaturation of alpha-amylase from Aspergillus oryzae showed a discontinuous transition into the denatured conformation, which exhibited much slower electrophoretic mobility. The discontinuity is due to an irreversible denaturation process under the gel conditions. The transition temperature was measured as a function of several parameters, e.g., the concentration of Ca(+)+, dithiotreithol, urea and the pH value. The structural transition of alpha-amylase is accompanied by a loss of enzymatic activity as determined by activity staining or by an activity assay carried out in solution. The structural transitions of two other alpha-amylases from Bacillus subtilis and Bacillus licheniformis were also studied. The results show that the TGGE method is simple to perform and allows the analysis of conformational transitions of proteins in a wide variety of conditions.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
108.
Positron annihilation lifetime spectroscopy was used to study the time dependence of the ortho-positronium lifetime and intensity and the ortho-positronium lifetime distribution in a poly(ethylene oxide)/poly(methyl methacrylate) blend after heat treatment. The recently introduced maximum entropy for lifetime analysis (MELT) program and the POSITRONFIT program were used for evaluation of the spectra. The blend shows a large excess in free volume hole size shortly after cooling from the melt. Withi time, the hole size decreases, while the orthio-positronium intensity remains constant. The lifetime distribution width does njot vary systematically with time. Differential scanning calorimetry measurements show that crystallisation of the poly(ethylene oxide) phase occurs parallel to the decrease in ortho-positronium lifetime. 相似文献
109.
By a modified Algar-Flynn-Oyamada reaction Betuletol, the 4',6-dimethylether of 6-hydroxy-kaempferol has been synthesized. The 3,7-dimethylether of the same flavonol and the isomeric 3,7-dimethyl-8-hydroxy-kaempferol (3,7-dimethyl-herbacetin) have been obtained by a modified Allan-Robinson synthesis. The syntheses confirm the structure of new flavonols from Betula and Ainus species as well as from Parthenium hysterophorus L. and Larrea tridentata Cav. 相似文献
110.
E. Maurer F. Hartmann F. Mylius F. Foerster G. Schoene H. Schenck Alexander Fischer G. T. Dougherty M. Dittrich A. Leonhard O. L. Barnebey J. V. Mc Crae R. L. Dowdell L. Jordan J. G. Thompson J. S. Acken J. H. S. Dickenson P. Herasymenko G. Pondélik Th. R. Cunningham R. J. Price C. H. Herty G. R. Fitterer J. E. Eckel J. J. Egan W. Crafts A. B. Kinzel 《Analytical and bioanalytical chemistry》1935,101(1-2):50-53