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931.
The viscosity behavior, index of refraction, and density of dilute polycaproamide solutions in DMAc containing lithium chloride have been studied. On the basis of temperature dependences of the index of refraction and the density of solutions, the θ-condition of polycaproamide solutions in DMAc containing 2.5% lithium chloride is estimated as 21.3°C. From intrinsic viscosity [η] measurements, the coefficients of swelling of a polymer coil, the mean-square distance between chain ends, and other parameters of macromolecules in solution are calculated. 相似文献
932.
A. P. Tyutnev R. Sh. Ikhsanov E. L. Grin’ G. P. Safonov A. I. Kononenko A. M. Sorokin I. V. Rudenko 《Polymer Science Series A》2006,48(11):1190-1195
A general theory of the phenomenon of recovered voltage in polymers was considered on the basis of representation of an actual poling process by a discrete set of Debye relaxators. Examples of numerical solution of the direct and inverse problems are given. A correlation expression between intentionally aged polymer specimens and recovered-voltage curves was proposed for use in the assessment of the material state of a polymer under actual service conditions. It was shown that it is sufficient to restrict consideration to three relaxation processes in analysis of the phenomenon. 相似文献
933.
X.J. Liu E.Y. Jiang Z.Q. Li B.L. Li W.R. Li A. Yu P. Wu H.L. Bai 《Journal of magnetism and magnetic materials》2006
We have investigated the magnetic, electrical transport and electron spin resonance (ESR) properties of polycrystalline Nd0.85Na0.15MnO3 prepared by sol–gel method. A ferromagnetic–paramagnetic (FM–PM) transition is observed around 110 K, which is not accompanied by a metal–insulator transition. The sample displays the complete PM state associated with the ESR spectra fitted by single Lorentzian line shape above 130 K. Below 130 K, ESR spectra become distorted and then linewidth increases rapidly, where short-range magnetic order develops and coexists with PM phase due to the inhomogeneous magnetic state. In addition, the large difference between the activation energies obtained from the resistivity and ESR parameters (peak-to-peak linewidth and line intensity) at the frame of adiabatic small polaron hopping model is pointed out for Nd0.85Na0.15MnO3. 相似文献
934.
935.
A. E. Stuchbery C. E. Doran A. P. Byrne H. H. Bolotin G. D. Dracoulis 《Hyperfine Interactions》1987,36(1):75-96
Transient-field strengths were measured for52Cr ions traversing polarized Fe hosts at velocities up to 12υ0 (12υ0 =c/137 = Bohr velocity). The results are compared with predictions of various transient-field parametrizations and discussed
in terms of possible mechanisms by which polarization might be transferred from the Fe host to inner vacancies of the moving
Cr ions. Theg-factor of the first 2+ state of52Cr was also measured by the transient-field technique and found to be in accord with shell model calculations. 相似文献
936.
von Eynatten G. Ritter T. Bömmel H. E. Dransfeld K. 《Zeitschrift für Physik B Condensed Matter》1987,65(3):341-345
A new model is presented which explains well the dramatic decrease of the Mössbauer line intensities with raising temperatures for freely dispersed iron microscrystals. In contrast to other theories which consider mainly vibration to be responsible we discuss here the decrease in terms of large amplitude diffusive rotational or translational jumps of the particles. Such diffusive jumps lead — in agreement with the observation — to a strong reduction of the Mössbauer-intensity without broadening the line width in a noticeable way. The typical potential well for a diffusing particle in an equilibrium position is derived quantitatively to be 13 meV. The model might be important also for a new understanding of the dynamics of catalytic clusters either in contact with each other or with larger solid surfaces.Part of this work was supported by the DFG Sonderforschungsbereich 306, Konstanz 相似文献
937.
Danny E. Akin W. Herbert Morrison III Luanne L. Rigsby Franklin E. Barton II David S. Himmelsbach Kevin B. Hicks 《Applied biochemistry and biotechnology》2006,129(1-3):104-116
Information is presented on structure, composition, and response to enzymes of corn stover related to barriers for bioconversion
to ethanol. Aromatic compounds occurred in most tissue cell walls. Ferulic acid esterase treatment before cellulase treatment
significantly improved dry weight loss and release of phenolic acids and sugars in most fractions over cellulase alone. Leaf
fractions were considerably higher in dry weight loss and released sugars with esterase treatment, but stem pith cells gave
up the most phenolic acids. Results help identify plant fractions more appropriate for coproducts and bioconversion and those
more suitable as residues for soil erosion control. 相似文献
938.
A planar metamaterial structure consisting of two layers of split-ring resonator (SRR) arrays is demonstrated to form the
image of a point source with subwavelength resolution. The source frequency is swept through the resonance gap of the metamaterial
layers and the lateral field intensity distribution is recorded on the transmission side of the metamaterial. When the source
is tuned to the resonance frequency of SRRs, the metamaterial acts as a high permeability medium and a distinct image with
subwavelength resolution in the lateral direction is obtained. Increasing the distance between the individual SRR layers reduces
the interlayer coupling, and the intensity and spatial resolution of the image decrease rapidly. 相似文献
939.
The prepared amorphous
γ-ZrP\SiO2 composite had a complicated composition,
since a part of γ-ZrP is converted to α-form during the exfoliation
of it. The γ-ZrP\SiO2 composite have specific surface
area of 421 m2g–1.
The acidic P–OH groups of the lamellae species placed on the surface
(it is ≈1.0 meq g–1), do not destroy until
the temperature of 1030 K. During the thermal treatment the total mass loss
of 7.79% was found. This value corresponds to 0.42 mole of H2O
per molecule unit. The water loss process was found very slow, because of
the placing of bilamellar species in the composite. 相似文献
940.
I. P. Dobrovol’skaya M. V. Mokeev Yu. N. Sazanov A. V. Gribanov T. E. Sukhanova 《Russian Journal of Applied Chemistry》2006,79(8):1312-1315
Variation of the supramolecular structure of heat-resistant polymide films in the course of high-temperature treatment was studied by X-ray diffraction analysis and NMR spectroscopy in solids. 相似文献