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11.
Josef Mehr 《Zeitschrift für Physik A Hadrons and Nuclei》1967,204(4):345-350
Various non-leptonic decay modes of baryons are calculated in a simple quark model. Form factors for various matrix elements are taken both from experiment and the quark model. Additionally theK→2π andK→3π decay modes are computed in the same model. The theory has theΔ I=1/2 rule and static SU6 built-in. A relation between the∑ +→N + π + decay, not calculable in the model, and theK→3π decay is given via an effective six quark interaction. Agreement with experiment is order of magnitude for the baryonic decays and worse for theK decays. 相似文献
12.
13.
SHUbarICHI NOSÉ 《Molecular physics》2013,111(1):191-198
A molecular dynamics simulation method which can generate configurations belonging to the canonical (T, V, N) ensemble or the constant temperature constant pressure (T, P, N) ensemble, is proposed. The physical system of interest consists of N particles (f degrees of freedom), to which an external, macroscopic variable and its conjugate momentum are added. This device allows the total energy of the physical system to fluctuate. The equilibrium distribution of the energy coincides with the canonical distribution both in momentum and in coordinate space. The method is tested for an atomic fluid (Ar) and works well. 相似文献
14.
The aim of this study was to measure the shear modulus of the vocal fold in a human hemilarynx, such that the data can be related to direction of applied stress and anatomical context. Dynamic spring rate data were collected using a modified linear skin rheometer using human hemilarynges, and converted to estimated shear modulus via application of a simple shear model. The measurement probe was attached to the epithelial layer of the vocal fold cover using suction. A sinusoidal force of 3g was applied to the epithelium, and the resultant displacement logged at a rate of 1kHz. Force measurement accuracy was 20microg and position measurement accuracy was 4microm. The force was applied in a transverse direction at the midmembranous point between the vocal process and the anterior commissure. The shear modulus of the three female vocal folds ranged from 814 to 1232Pa. The shear modulus of the three male vocal folds ranged from 1021 to 1796Pa. These data demonstrate that it is possible to obtain estimates for the shear modulus of the vocal fold while preserving anatomical context. The modulus values reported here are higher than those reported using parallel plate rheometry. This is to be expected as the tissue is attached to surrounding structures, and is under natural tension. 相似文献
15.
We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the
central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density
distribution. 相似文献
16.
We study the binding and deconfinement of heavy quarks in a thermal environment, using a non-relativistic confinement potential model with color screening. As a result, we obtain the dependence of the dissociation energies, the binding radii and the masses of heavy quark resonances (charmonium and bottonium states) on the color screening lengthr D of the medium, and we determine for the different resonances those values ofr D below which no more binding is possible. Finally, we consider the implication of our results on resonance suppression as signal for deconfinement. 相似文献
17.
Stetter M. Felsner P. Christiansen J. Frank K. Gortler A. Hintz G. Mehr T. Stark R. Tkotz R. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(3):283-293
The intention of this paper is to give an overview of recent experiments explaining the development and transition of the discharge phases in a pseudospark. The reported experiments include single gap pseudospark discharges in ultra-high-vacuum systems with hydrogen as working gas, as well as multigap pseudospark discharges in argon. Temporally and spatially resolved framing photography, spectrometry, raster electron microscopy and time resolved electrical measurements are presented. The experiments comprise a current range of some hundreds of amps to 60 kA. The results are used to specify the four characteristic phases of the pseudospark: Townsend-, hollow cathode-, high current- and metal vapor arc phase 相似文献
18.
Ali Nakhaei Pour Yahya Zamani Kheirolah Jafari Jozani Jafar Yeganeh Mehr 《Reaction Kinetics and Catalysis Letters》2005,86(1):157-162
Summary The effect of La2O3 and TiO2 on product selectivity, methane conversion and coke formation over NiO/MgO/ α -Al2O3 catalyst were studied in a simultaneous steam and CO2 reforming of methane to syngas. La2O3 and TiO2 were added to the catalyst via incipient wetness impregnation and bulk precipitation techniques and catalyst activity was tested in a fixed bed quartz reactor. Results reveal that although the addition of these oxides has no effect on the product selectivity and methane conversion, but can reduce coke formation on the surface of the catalysts as it can enhance the mobility of lattice oxygen anions. The results further show that the catalysts prepared by bulk precipitation technique decrease the coke formation more effectively. 相似文献
19.
Bob Stanley Kevin A. Mehr Trent Kellock Jonathan D. Van Hamme Kingsley K. Donkor 《Journal of separation science》2009,32(17):2993-3000
A sensitive micellar electrokinetic chromatography (MEKC) method was developed for the separation and determination of four closely related lantibiotics: gallidermin, cinnamycin, duramycin and nisin. Factors affecting the separation of the lantibiotics such as pH, phosphate buffer concentration, SDS concentration and wavelength for UV detection were investigated. By optimizing these experimental conditions, successful separation was achieved between class 1A lantibiotics (nisin and gallidermin) and class 1B lantibiotics (duramycin and cinnamycin). The four lantibiotics were separated within 12 min in 50 mM phosphate buffer at pH 3.95 ± 0.1 containing 80 mM SDS with UV detection of 214 nm. The LOD (S/N = 3) were 61 ng/mL for gallidermin, 57 ng/mL for cinnamycin, 55 ng/mL for duramycin and 58 ng/mL for nisin. The method was successfully applied to real samples such as fermentation broth, bovine colostrum and predrop beer. This method yielded satisfactory results, with quantitative recoveries of spiked lantibiotics in the three samples ranging from 86.1 to 99.6%. 相似文献
20.
Polyacrylonitrile (PAN) grafted chitosan was prepared by ceric‐initiated graft polymerization of acrylonitrile onto chitosan in a homogenous medium. The copolymer chitosan‐g‐PAN product was then hydrolyzed to yield a novel smart hydrogel (H‐chitoPAN) with superabsorbing properties. The influence of add‐on values as well as temperature and time of hydrolysis of the initial chitosan‐g‐PAN on swelling behavior of the hydrogel was evaluated in water and various salt solutions. The swelling kinetics of the superabsorbing hydrogel was studied as well. The hydrogels exhibited ampholytic and pH‐sensitivity characteristics. Several sharp swelling changes were observed in lieu of pH variations in a wide range (pH 2–13). The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. Superabsorbency, pH‐ and salt‐sensitivity of the chitosan‐based hydrogel was briefly compared with the classical starch‐based superabsorbent, H‐SPAN. The pH‐reversibility and on–off switching behavior of the intelligent H‐chitoPAN hydrogels makes them good candidates for considering as potential drug carries. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献