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841.
Y. P. Khanna W. P. Kuhn J. E. Macur A. F. Messa N. S. Murthy A. C. Reimschuessel R. L. Schneider J. P. Sibilia A. J. Signorelli T. J. Taylor 《Journal of Polymer Science.Polymer Physics》1995,33(7):1023-1030
A peculiar phenomenon is reported whereby a melt-extruded, low-crystallinity, unoriented film of poly(chlorotrifluoroethylene) upon unconstrained thermal treatment, self-extends in the machine direction (MD) while shrinking along the transverse (TD) and normal/thickness (ND) directions. In addition to the expected increase in crystallinity, the annealing process leads to an unexpected development of crystalline orientation along the MD. This phenomenon is an example of “processing-induced memory effects” since it depends on the processing history of the starting film, e.g., melt-extrusion leads to the subject behavior whereas compression molding does not. We must mention that the melt-extruded films of poly(chlorotrifluoroethylene) are isotropic to start with, that is, MD and TD are indistinguishable prior to the annealing process. Furthermore, this phenomenon has not been observed for any other semicrystalline polymer and is believed to be the first citation for poly(chlorotrifluoroethylene) since its commercialization in 1957. Thermomechanical analysis (TMA) is the analytical technique that led to this novel phenomenon which was later substantiated by x-ray diffraction (XRD). ©1995 John Wiley & Sons, Inc. 相似文献
842.
E. Lewitzki U. Frank E. Götz K. Brand F. W. Schneider E. Grell 《Journal of fluorescence》1994,4(4):287-290
The interaction between the fluorescent ouabain derivative DEDO and purified renal Na,K-ATPase (isolated from different animal species) is investigated. Equilibrium binding studies provide a pK value of about 7.5 and a stoichoimetric coefficient of 1. Nonmodified ouabain exhibits the same affinity to the rabbit enzyme; the enzyme originating from the other sources binds DEDO 10 times less strongly than ouabain. Kinetic studies indicate that this is the consequence of a 10 times higher dissociation rate constant of the complexes formed with DEDO. The fluorescence emission intensity of DEDO is enhanced, being dependent on the enzyme source. The single decay time of DEDO is 3 ns in the absence and 21 ns in the presence of the rabbit enzyme and 14 ns in the presence of the pig renal enzyme. This result suggests that the fluorophore of DEDO is bound to a very hydrophobic environment of the enzyme. Further characterization of the static fluorescence spectra provides evidence for energy transfer between Trp residues of the enzyme and DEDO. Distance estimations suggest that one or two Trp residues are likely to be located in the proximity of the fluorophore. 相似文献
843.
G. Münzenberg P. Armbruster S. Hofmann F. P. Heßberger H. Folger J. G. Keller V. Ninov K. Poppensieker A. B. Quint W. Reisdorf K. -H. Schmidt J. R. H. Schneider H. -J. Schött K. Sümmerer I. Zychor M. E. Leino D. Ackermann U. Gollerthan E. Hanelt W. Morawek D. Vermeulen Y. Fujita T. Schwab 《Zeitschrift für Physik A Hadrons and Nuclei》1989,334(2):163-175
A new and transparent method for the analysis of recoil distance Doppler shift data is presented, which we call thedifferentialdecay curve method (DDCM). The DDCM can be used for singles as well as for coincidence plunger data and systematic errors can be discovered with it much easier than in the conventional analysis. In addition we propose a modification of the normal plunger which we call the differential plunger. With the differential plunger in principle it is possible to determine lifetimes from quantities measured at only one target to stopper distance. The DDCM was tested with lifetime data for120Xe and128Ba. 相似文献
844.
Let A be an M-matrix. We introduce the concepts of height basis, level basis, and height-level basis for the generalized nullspace of A. We explore the properties of such bases and of induced matrices. We use these results to prove some new conditions for the equality of the (spectral) height (Weyr) characteristic and the (graph theoretic) level characteristic of A, and to simplify proofs of known conditions. We also prove the existence of a Jordan basis for the generalized nullspace with all chains of maximal length nonnegative. 相似文献
845.
846.
Erwin P. Enriquez Hildegard M. Schneider Steve Granick 《Journal of Polymer Science.Polymer Physics》1995,33(17):2429-2437
Polarized infrared spectroscopy in attenuated total reflection was used to investigate the adsorption of PMMA (polymethylmethacrylate) onto PS (polystyrene) that was previously adsorbed onto oxidized silicon from dilute solution in carbon tetrachloride at 30°C. The carbonyl group of PMMA forms hydrogen bonds with surface silanol groups, giving segment-surface interaction energy of 4 kT as against 1 kT for PS (k is the Boltzmann constant, T the absolute temperature). The formation of hydrogen-bonding by PMMA was unaffected, in rate or amount, by preadsorbed PS, but a lesser total amount of PMMA adsorbed onto PS, resulting in a higher average bound fraction. The histogram of the mass adsorbed, attributable to subpopulations of chains with different bound fractions, was inferred by subtracting infrared spectra acquired at successive times. Whereas this histogram was broad and bimodal for adsorption onto bare surface, it was narrower and unimodal for adsorption onto preadsorbed PS. © 1995 John Wiley & Sons, Inc. 相似文献
847.
848.
Kurt Busch Guido Schneider Lasha Tkeshelashvili Hannes Uecker 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2006,341(2):905-939
The dynamics of the envelopes of spatially and temporarily oscillating wave packets advancing in spatially periodic media
can approximately be described by solutions of a Nonlinear Schr?dinger equation. Here we prove estimates for the error made
by this formal approximation using Bloch wave analysis, normal form transformations, and Gronwall’s inequality. 相似文献
849.
On the Hydration and Dehydration Behaviour of Magnesium Hydrogensulfate Mg(HSO4)2 · H2O has been prepared by crystallization from diluted sulfuric acid. The thermal destruction leads to the formation of siccative Mg(HSO4)2. This process is reversible, i. e., Mg(HSO4)2 rehydrates during cooling under formation of Mg(HSO4)2. H2O. Due to further water reception Mg(HSO4)2 · H2O decomposes at a temperature of 50°C forming Kieserite (MgSO4 · H2), MgSO4 · 1,25H2O, sulfuric acid, and water. During gentle warming of this heterogenous phase mixture it reacts under reconstruction of Mg(HSO4)2 · H2O. The thermal measurements have been carried out in dynamic as well as in static gas atmosphere. The strong dependence of the decomposition temperatures from the partial pressure of the gaseous products could be demonstrated by in situ X-ray measurements. 相似文献
850.
A. Hünger J. Peise A. Robbiano J. Ahrens I. Anthony H. -J. Arends R. Beck G. P. Capitani B. Dolbilkin H. Falkenberg G. Galler S. J. Hall J. D. Kellie R. Kondratjev R. Kordsmeier V. Lisin A. I. L''vov G. J. Miller C. Molinari P. Ottonello A. R. Reolon M. Sanzone M. Schmitz M. Schneider M. Schumacher O. Selke Th. Walcher F. Wissmann S. Wolf A. Zucchiatti 《Nuclear Physics A》1997,620(4):385-416
Differential cross sections for Compton scattering by the proton have been measured in the energy interval between 200 and 500 MeV at scattering angles of θcms = 75° and θcms = 90° using the CATS, the CATS/TRAJAN, and the COPP setups with the Glasgow Tagger at MAMI (Mainz). The data are compared with predictions from dispersion theory using photo-meson amplitudes from the recent VPI solution SM95. The experiment and the theoretical procedure are described in detail. It is found that the experiment and predictions are in agreement as far as the energy dependence of the differential cross sections in the Δ-range is concerned. However, there is evidence that a scaling down of the resonance part of the M1+3/2 photo-meson amplitude by (2.8 ± 0.9)% is required in comparison with the VPI analysis. The deduced value of the M1+3/2-photoproduction amplitude at the resonance energy of 320 MeV is: |M1+3/2| = (39.6 ± 0.4) × 10−3 mπ+−1. 相似文献