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61.
Rashid A. Zeineh George Kyriakidis A. Rashid Bhatti 《Applied biochemistry and biotechnology》1986,13(2):111-117
Virion polypeptides (35 S), methionine-labeled and purified by CsCl gradient centrifugation, were separated by SDS-gel electrophoresis. Analysis of their band pattern was performed by scanning the images of the SDS-gels shown on a 35-mm slide. The densitometric tracings revealed the presence of 17 protein bands, although only 15 of them were visible to the naked eye. The high sensitivity and resolving capacities of the soft-laser scanning densitometer enabled us to detect trace amounts of protein bands separated in SDS-gels and to obtain a resolution compatible to that of electrophoresis. Fourfold electronic amplification of the densitometric tracings, produced by a computer, generated new information regarding the pattern of the electrophoregram. The facility to amplify peaks of importance is particularly advantageous when faint or overlapping protein bands revealed on a gel are assessed. 相似文献
62.
The thermal and photochemical fragmentations of a few bisazoalkenes have been investigated. 2-Phenyl-4,5-disubstituted-1, 2,3-triazoles were obtained both in the thermolysis and photolysis of 1, 2-bisphenylazo-(4, 4′-dichloro) stilbene, 1, 2-bisphenylazo(4, 4′-dimethoxy)stilbene, 1, 2-bisphenylazocyclohexene and o-(phenylazo) phenyldiazocyanide. Both 2, 3-bisphenylazo-2-butene and 1, 2-bisphenylazoethylene failed to undergo either photolysis or thermolysis in the expected manner. However, 2, 3-bisphenylazo-2-butene underwent an acid-catalysed valence isomerisation to anhydro 1-phenylimino-2-phenyl-4, 5-dimethyl-1, 2, 3-trizolium hydroxide, which on photolysis gave 2-phenyl-4, 5-dimethyl-1, 2, 3-triazole. The same iminotriazolium intermediate gave a cycloadduct, 2, 6-diphenyl-3, 3a-dimethyl-4, 5-dicarbomethoxypyrazolino [2.3.c][1.2.3] triazole, on treatment with dimethyl acetylenedicarboxylate, whereas treatment with carbon disulphide gave 2-phenyl-4, 5-dimethyl-1, 2, 3-triazole. Both photolysis and thermolysis of C-biphenylene-Nα(4-chlorophenyl)-Nβ-cyanoazomethine imine gave 9-fluorenone-N- (4-chlorophenyl) anil. Photolysis of 1, 2-bisphenylazoacenaphthylene in methanol gave acenaphthenequinone monophenylhydrazone. 相似文献
63.
A hierarchical family of five three-dimensional potential energy surfaces has been developed for the benchmark He-CO system. Four surfaces were obtained at the coupled cluster singles and doubles level of theory with a perturbational estimate of triple excitations, CCSD(T), and range in quality from the doubly augmented double-zeta basis set to the complete basis set (CBS) limit. The fifth corresponds to an approximate CCSDT/CBS surface (CCSD with iterative triples/CBS, denoted CBS+corr). The CBS limit results were obtained by pointwise basis set extrapolations of the individual counterpoise-corrected interaction energies. For each surface, over 1000 interaction energies were accurately interpolated using a reproducing kernel Hilbert space approach with an R-6+R-7 asymptotic form. In each case, both three-dimensional and effective two-dimensional surfaces were developed. In standard Jacobi coordinates, the final CBS+corr surface has a global minimum at rCO=2.1322a0,R=6.418a0, and gamma=70.84 degrees with a well depth of -22.34 cm-1. The other four surfaces have well depths ranging from -14.83 cm-1 [CCSD(T)/d-aug-cc-pVDZ] to -22.02 cm-1 [CCSD(T)/CBS]. For each of these surfaces the infrared spectrum has been accurately calculated and compared to experiment, as well as to previous theoretical and empirical surfaces. The final CBS+corr surface exhibits root-mean-square and maximum errors compared to experiment (4He) of just 0.03 and 0.04 cm-1, respectively, for all 42 transitions and is the most accurate ab initio surface to date for this system. Other quantities investigated include the interaction second virial coefficient, the integral cross sections, and thermal rate coefficients for rotational relaxation of CO by He, and rate coefficients for CO vibrational relaxation by He. All the observable quantities showed a smooth convergence with respect to the quality of the underlying interaction surface. 相似文献
64.
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66.
We study a queueing system withm exponential servers with distinct service rates. Jobs arrive at the system following an arbitrary point process. Arrived jobs receive service at the first unoccupied server (if any) according to an entry order , which is a permutation of the integers 1, 2,...,m. The system has a finite buffer capacity. When the buffer limit is reached, arrivals will be blocked. Blocked jobs will either be lost or come back as New arrivals after a random travel time. We are concerned with the dynamic stochastic behavior of the system under different entry orders. A partial ordering is established among entry orders, and is shown to result in some quite strong orderings among the associated stochastic processes that reflect the congestion and the service characteristics of the system. The results developed here complement existing comparison results for queues with homogeneous servers, and can be applied to aid the design of conveyor and communication systems. 相似文献
67.
The synthesis and transition temperatures of some trans-4-alkylcyclohexylethyl-substituted 2,3-difluorobiphenyls 总被引:1,自引:0,他引:1
Terphenyls with two lateral ortho-fluoro-substituents have proved to be excellent host materials for ferroelectric (SC*) mixtures. The compounds reported here are biphenyls with the same arrangement of lateral substituents but with a trans-4-alkylcyclohexylethyl moiety as one of the terminal substituents. Such three ring systems retain the ability to generate the SC mesophase and have low melting points. Low temperature lithiation procedures were used to prepare phenylboronic acids, which were then used in palladium catalysed cross-coupling procedures to prepare the desired compounds. The effect of molecular structure on the mesophase types and thermal stabilities is discussed and comparisons are made with analogous terphenyls and biphenyls with open chain terminal substituents. 相似文献
68.
Walrafen GE 《The Journal of chemical physics》2004,121(6):2729-2736
The dispersion of the H-bond pair volume Delta V over the decoupled OD and coupled OH-stretching contours from HDO in H(2)O was determined from Raman intensities at pressures to 9700 bar at 301 K. The dispersion of Delta V was determined from -RT[partial differential ln(I(i)/I(REF))/ partial differential P](T) versus omega (in cm(-1)), where i refers to omega's over the stretching contours and I(REF) refers to the reference intensity at the isosbestic frequency. The maximum H-bond pair volume (defined for breakage) is 1.4+/-0.1 cm(3)/mol H-bond, which corresponds to the volume difference between a large dispersion maximum at 2,675 cm(-1) (near the OD stretch omega of HDO in dense supercritical water) and a large, broad minimum centered near 2,375 cm(-1) (just below the OD stretch omega of HDO in lda ice). The average DeltaV is 0.71+/-0.10 cm(3)/mol H-bond. Other minima near 2,625 cm(-1) (OD) and 3550 cm(-1) (OH) refers to bent H-bonds whose angles are approximately 150 deg. Isothermal pressurization of water lowers the molal volume by decreasing the concentration of long, weak H-bonds, and increasing the concentrations of bent H-bonds and short, strong, linear H-bonds. Such bending, shortening, and strengthening produces freezing to ice VI near 10 kbar at 301 K. The isobaric temperature derivative of the maximum H-bond volume is (partial differential Delta V/partial differential T)(P)< or =(2-5) x 10(-3) cm(3)/deg mol H-bond. The OH enthalpy dispersion curve for saturated NaBF(4) in water, yields a large maximum at 3,530-3,540 cm(-1) indicating that BF(4) (-) interacts preferentially with the dangling or "free" OH groups of water thus producing weak, strongly bent H-bonds having angles similar to those of the 3,550 cm(-1) high-pressure H-bond bending feature. 相似文献
69.
Haes AJ Zhao J Zou S Own CS Marks LD Schatz GC Van Duyne RP 《The journal of physical chemistry. B》2005,109(22):11158-11162
A novel method to produce solution-phase triangular silver nanoparticles is presented. Ag nanoparticles are prepared by nanosphere lithography and are subsequently released into solution. The resulting nanoparticles are asymmetrically functionalized to produce either single isolated nanoparticles or dimer pairs. The structural and optical properties of Ag nanoparticles have been characterized. Mie theory and the Discrete Dipole Approximation method (DDA) have been used to model and interpret the optical properties of the released Ag nanoparticles. 相似文献
70.
A semiclassical transition amplitude is derived for electronically inelastic molecular collisions in the presence of an intense electromagnetic field. The calculation of this amplitude involves the integration of classical trajectories for nuclei moving on effective potential energy surfaces. These surfaces, which exhibit an avoided crossing due to the coupling through the dipole interaction around the resonance nuclear configuration, are analytically continued to their complex intersection points, where trajectories switch surfaces. Other parts of these surfaces are similar to the field-free adiabatic surfaces, where one is shifted by ?ω. Metastable states, formed at some collision energies, are suggested in the field which are absent in the field-free system. 相似文献