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131.
C. S. Nie F. Kremer A. Poglitsch G. Bechtold L. Genzel 《Journal of Polymer Science.Polymer Physics》1985,23(6):1247-1254
Absorption measurements at millimeter-wave frequencies (50–151 GHz) are reported for dried and hydrated polyamide-6. The measurements were extended over the temperature range from liquid helium to room temperature using the oversized-cavity technique. For dried polyamide-6 (water content ≤ 0.5% w/w), a nearly linear increase with frequency and an exponential increase with temperature of the absorption coefficient is found between 50 and 300 K. This frequency and temperature dependence is described by relaxation processes in asymmetric double-well potentials. The observed relaxation times are on a picosecond time scale, thus suggesting an assignment to the NH…OC hydrogen bonds and the adjacent peptide unit (O?C? N? H). Hydration results in an increase of the absorption over the whole temperature and frequency range. This is attributed to the fact that the water of hydration is adsorbed in the neighborhood of the hydrogen bonds and changes their dynamical properties. This interpretation is supported by IR-spectroscopic measurements of the shift of amide I and amide II after hydration. 相似文献
132.
Mazhar-Ul-Haque Jamil Ahmed William Horne Sheldon E. Cremer Pawel K. Kafarski Paul W. Kremer 《Journal of chemical crystallography》1989,19(6):1009-1016
The title compound crystallizes in the orthorhombic space groupPna21, witha=15.576(2),b=19.134(3),c=5.693(1) Å andz=4. The structure was solved by direct methods, and refined to a finalR value of 0.059. This study confirms both the structure and stereochemistry of the title compound. 相似文献
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This paper describes an attempt to study the electrophoresis mobility of a DNA molecule in a gel by means of a Monte Carlo simulation. We find that the electrophoresis mobility mu can be well described by the empirical equation mu v kappa 1/N + kappa 2E2 with N being the number of monomers of the model chain and E being the applied field. For small E the data can merge into the linear response result mu = kappa 1/N. The paper also discusses necessary extensions of the present approach. 相似文献
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R.K. Kremer K. Graf G.G. Devyatykh A.M. Gibin A.N. Taldenkov 《Solid State Communications》2004,131(8):499-503
The thermal conductivity of isotopically enriched 28Si (enrichment better than 99.9%) was redetermined independently in three laboratories by high precision experiments on a total of four samples of different shape and degree of isotope enrichment in the range from 5 to 300 K with particular emphasis on the range near room temperature. The results obtained in the different laboratories are in good agreement with each other. They indicate that at room temperature the thermal conductivity of isotopically enriched 28Si exceeds the thermal conductivity of Si with a natural, unmodified isotope mixture by 10±2%. This finding is in disagreement with an earlier report by Ruf et al. At ∼26 K the thermal conductivity of 28Si reaches a maximum. The maximum value depends on sample shape and the degree of isotope enrichment and exceeds the thermal conductivity of natural Si by a factor of ∼8 for a 99.982% 28Si enriched sample. The thermal conductivity of Si with natural isotope composition is consistently found to be ∼3% lower than the values recommended in the literature. 相似文献