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141.
Mordechai Shporer Alexander J. Vega Moshe A. Frommer 《Journal of Polymer Science.Polymer Physics》1974,12(4):645-654
The NMR spectra of water adsorbed at various relative humidities on various cellulose ester membranes have been studied. Membranes of cellulose acetate (CA), cellulose triacetate (CTA), and cellulose acetate butyrate (CAB) were investigated. It was found that the resonance peak of a liquid imbibed in or adsorbed on membranes from high relative humidity is very sensitive to the angle between the membrane plane and the direction of the magnetic field, shifting 5–7 ppm to higher fields as the membrane plane is rotated from a perpendicular to a parallel position with respect to the direction of the external magnetic field. This phenomenon was found to be independent of the nature of the polymeric material (namely CA, CTA, or CAB), porosity of the membrane (varying from an “all bulk” dense sheet to an 80% porosity and 0.2 μm average pore size membrane), nature of the magnetic nuclei (H2O or D2O), intensity of the external magnetic field (60 Mcps or 100 Mcps), and nature of the liquid in the membrane (water, methanol, or n-hexane). It is therefore concluded that the dependence of the position of the resonance peak on the position of the membrane plane with respect to the external magnetic field, is a geometrical phenomenon due to the magnetic “bulk susceptibility” of the medium. Quantitative estimations of the magnitude of the diamagnetic susceptibility effect in a cylindrically rolled sheet are given. These estimates agree well with the experimentally observed “splittings.” 相似文献
142.
V. Cook G. Hicks P.M. Mockett J.E. Rothberg R.W. Williams K.K. Young P. Limon P. Mantsch J.R. Orr S. Pruss W.P. Oliver 《Nuclear Physics B》1981,186(2):219-235
Large aperture calorimeter measurements of high transverse momentum events from 100, 200 and 340 GeV pp collisions are reported. Yields are higher by one to two orders of magnitude than the yield expected from uncorrelated statistical fluctuations in multiparticle events. The exponential slopes of the yields versus xt exhibited a systematic change with . The events are shown to be more diffuse than pure jets as produced in e+e? collisions. However, these events are consistent with a QCD-inspired 4-jet model. 相似文献
143.
H. De Kerret E. Nagy R.S. Orr M. Regler W. Schmidt-Parzefall K. Winter A. Brandt H. Dibon G. Flügge F. Niebergall P.E. Schumacher K.R. Schubert J.J. Aubert C. Broll G. Coignet J. Favier L. Massonnet M. Vivargent G. Neuhofer 《Physics letters. [Part B]》1977,69(3):372-376
We report on a study of the charge-exchange reaction pp → nΔ++(1232) at the CERN intersecting storage rings (ISR) in the energy range √s = 23 to 53 GeV. From our analysis of the energy dependence of the total cross-section, of the differential cross-section dσ/dt and of the decay angular distributions we find evidence that pion exchange is dominant up to √s = 23 GeV and that (?+A2) exchange dominates the reaction for √s ? 30 GeV, as described by simple Regge-pole models. 相似文献
144.
TOF spectra of scattered primary and surface recoiled neutrals and ions for 3 keV Ar+ bombardment of clean La and Yb and H2, O2, and H2O saturated La surfaces are presented. The spectra are analyzed in terms of single (SS) and multiple (MS) scattering of the primary ions and surface recoiling (SR) of adsorbate atoms. Measurement of spectra of neutrals + ions and neutrals alone allows determination of scattered ion fractions Y. The Y values for the SS event are high for clean La (37%) and lower for adsorbate covered La (32% for H2, 13% for O2, and 8% for H2O); Yb exhibits a similar behavior, i.e. 16% for clean Yb and 5% for O2 + H2O covered Yb. Photon emission accompanying the scattering collision has been observed from clean La and Yb and adsorbate covered La. A preferential inelastic energy loss of 15 ± 3 eV for the SS event has been observed for scattered neutrals as opposed to ions for La and H2 saturated La at 135°. These results are interpreted within the models for Auger and resonant electronic charge exchange transitions during approach or departure of an ion with a surface and the electron promotions occuring during close atomic encounters where the electron shells are interpenetrating. 相似文献
145.
For a one-parameter process of the form Xt=X0+∫t0φsdWs+∫t0ψsds, where W is a Wiener process and ∫φdW is a stochastic integral, a twice continuously differentiable function f(Xt) is again expressible as the sum of a stochastic integral and an ordinary integral via the Ito differentiation formula. In this paper we present a generalization for the stochastic integrals associated with a two-parameter Wiener process.Let {W2, z∈R2+} be a Wiener process with a two-dimensional parameter. Ertwhile, we have defined stochastic integrals ∫ φdWand ∫ψdWdW, as well as mixed integrals ∫h dz dW and ∫gdW dz. Now let Xz be a two-parameter process defined by the sum of these four integrals and an ordinary Lebesgue integral. The objective of this paper is to represent a suitably differentiable function f(Xz) as such a sum once again. In the process we will also derive the (basically one-dimensional) differentiation formulas of f(Xz) on increasing paths in . 相似文献
146.
147.
A rapid and simplified method for the determination of phase inversion temperature (PIT) and the stability of oil in water emulsions, stabilized by nonionic emulsifiers, is described. The method is based on the use of any thermogravimetric apparatus from which the rate of loss of water can be measured as a function of linear increase in the emulsion temperature. A DTG peak is obtained at the PIT: the emulsion in which the lowest PIT is observed is also the less stable one. 相似文献
148.
We show that, contrary to previous assertions, multi-pomeron couplings to the external particles are equally as important as single couplings in the asymptotic behaviour of the amplitude in the reggeon calculus. Our arguments require a careful discussion of the relation of the reggeon calculus to a renormalizable field theory and of the renormalization of composite operators in reggeon field theory. 相似文献
149.
In this paper we study inclusion relations between the following four classes of matrices: normal matrices, matrices with equal spectral radius and spectral norm, matrices whose numerical range coincides with the convex polygon spanned by their eigenvalues, and matrices with equal numerical and spectral radii. 相似文献
150.
Hessler JA Budor A Putchakayala K Mecke A Rieger D Banaszak Holl MM Orr BG Bielinska A Beals J Baker J 《Langmuir : the ACS journal of surfaces and colloids》2005,21(20):9280-9286
Apoptosis is defined by a distinct set of morphological changes observed during cell death including loss of focal adhesions, the formation of cell membrane buds or blebs, and a decrease in total cell volume. Recent studies suggest that these dramatic morphological changes, particularly apoptotic volume decrease (AVD), are an early prerequisite to apoptosis and precede key biochemical time-points. Here we use atomic force microscopy to observe early stage AVD of KB cells undergoing staurosporine-induced apoptosis. After a 3-h exposure to 1 microM staurosporine, a 32% decrease in total cell height and a 50% loss of total cell volume is observed accompanied by only a 15% change in cell diameter. The observed AVD precedes key biochemical hallmarks of apoptosis such as loss of mitochondrial membrane potential, phosphatidyl serine translocation, nuclear fragmentation, and measurable caspase-3 activity. This suggests that morphological volume changes occur very early in the induction of apoptosis. 相似文献