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51.
The effect of a parallel magnetic field on the 10-mHz surface resistance of gallium single crystals is reported. We suggest that the observed structure can be interpreted in terms of an angular dependence of the probability of specular reflection of the electron at the crystal surface. This model allows a quantitative determination from the data of the temperature-dependent electron mean free path for electron wave vectors with a narrow range that is determined by the magnetic field and crystal orientation. 相似文献
52.
Azam Niroomand-Rad Miu Yung Chan Paul M. Parker 《Journal of Molecular Spectroscopy》1978,69(3):450-457
Four linearly independent linear combinations of the ten sextic centrifugal distortion coefficients of triangular triatomic molecules are presented. These combinations are formed in such a way that the resulting expressions depend only on the equilibrium geometry and the harmonic force field parameters of the molecule, quantities which are ordinarily known to considerably better precision than the sextic constants. The relations obtained thus constitute a set of planarity constraints on the ten sextic coefficients which arise in connection with the Nielsen-Amat expansion of the Darling-Dennison Hamiltonian. The planarity expressions can be utilized to effect a reduction of the sextic portion of the Hamiltonian. 相似文献
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The relationship between the closed-shell repulsive interactions and overlap of the electron densities is investigated. It is found that the repulsive interactions vary in almost direct proportion to the absolute size of the density overlaps. 相似文献
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This research studied optical and structural properties of SrO-Nb2O5-P2O5 glasses containing 0 ~ 25 mol% Nb2O5 and 35 ~ 60 mol% SrO using spectra of UV-Vis, FTIR and XPS. Our aim was to work new moldable glasses which are colorless with high refractive index and transmittance, and their correlation with glass structure. Nb2O5 plays the role as an intermediate of glass formation, and transforms the role to network-former or glass-modifier depending on composition. Refractive index increases monotonically with Nb2O5 content at the expense of transmittance, and specific coloring which occurs in ternary compositions with the ratio P2O5/SrO > 1. This effect arises from much increased [Nb3+ and Nb4+] fraction, as quantitatively deconvoluted in Nb3d XPS spectra, in the ligand [NbO6]octahedral which is supported by FTIR and O1s XPS spectra. As the ratio P2O5/SrO ≤ 1, Nb2O5 is more of a network former and [NbO6]octahedral structure turns into [NbO4]tetrahedron with partial Nb-O…(Sr) bonding turns into (Nb-O-Nb)tetrahedron, coloring disappears. 相似文献
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Pei‐Chun Kuo Ya‐Ching Chang Chuh‐Yung Chen Chieh‐Tsung Lo 《Journal of Polymer Science.Polymer Physics》2015,53(3):192-202
The isothermal crystallization of poly(l ‐lactide) (PLLA) in blends with poly(butylene oxalate) (PBOX) is investigated by time‐resolved small‐angle X‐ray scattering, differential scanning calorimetry, and optical microscopy. We focus on the temperatures at which only PLLA crystallizes while PBOX is amorphous. It is obtained that the addition of PBOX causes a reduction of the melting temperature of PLLA. The lamellar thickness of PLLA crystals decreases whereas the amorphous layer thickness increases with blend composition, suggesting the occurrence of the interlamellar incorporation upon the addition of PBOX. The crystal growth rate and morphology of PLLA/PBOX blends are analyzed by polarized optical microscopy. The spherulite growth rate of PLLA is found to increase with the addition of PBOX. Analysis of the isothermal crystallization in terms of the Lauritzen and Hoffman equation give the reduction of the fold surface free energy upon the addition of PBOX in PLLA, indicating that the mobility of the PLLA chains is significantly improved due to the presence of PBOX. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 192–202 相似文献
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Fengyu Yang Baiping Ren Yongqing Cai Jianxin Tang Ding Li Ting Wang Zhangqi Feng Yung Chang Lijian Xu Jie Zheng 《Journal of polymer science. Part A, Polymer chemistry》2018,56(19):1294-1305
Development of functional tough hydrogels with new network structures and energy dissipation mechanisms has great promise for many applications. Here, a new type of physical hydrogel crosslinked by hydrophobic association and hydrogen bonds was synthesized by a facile micellar copolymerization of hydrophobic methyl acrylate (MA) monomers and hydrophilic N-hydroxyethyl acrylamide (HEAA) monomers in the presence of Tween80 micelles. Strong hydrophobic association between inner MA and Tween80 and hydrogen bonds between external polyHEAA and Tween80 provide two distinct crosslinkers to construct mechanically tough and recoverable network. Mechanical properties of polyHEAA-MA@Tween80 hydrogels strongly depended on network components (HEAA, MA; Tween80 concentrations). At optimal conditions, the hydrogels can achieve fracture stress of 700 kPa, fracture strain of 1687 mm/mm, elastic modulus of 195 kPa, and tearing energy of 1598 J/m2. Due to the reversible nature of physical interactions, polyHEAA-MA@Tween80 hydrogels can achieve fast stiffness/toughness recovery of 60%/33% without any external stimuli and resting time at room temperature. This work demonstrates a new design strategy to fabricate a new a single-network hydrogel with high mechanical and self-recovery properties by incorporating both hydrophobic association and hydrogen bonds in the network, which may provide alternative viewpoint for the design of multifunctional tough hydrogels. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1294–1305 相似文献