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751.
An integrated-wavelet-transform (IWT) approach is proposed for the study of scattering from slightly rough surfaces that manifest scaling properties over a finite domain of correlation lengths. Instead of collecting angle-resolved intensities, values of the irradiance integrated over increasing areas are used to enhance the contributions of small irradiances at large scattering angles and to reduce the coherent noise. In the case of self-similar surfaces, the scaling behavior of IWT allows investigation of the surface roughness at various length scales. For the realistic case of self-affine surfaces, IWT permits the evaluation of the scaling exponent of the autocorrelation and also offers a direct way to evaluate the necessary length scale of the surface profile. 相似文献
752.
[1-13C]Gly, L-[1-13C]Ala, [15N]Gly, L-[15N]Ala, [2,2-2H2]Gly, L-[3,3-2H2]Ser and [3,3,3-2H3]Ala labeled silk fibroin fibers from Bombyx mori and Samia cynthia ricini silkworms were prepared in order to analyze structure of backbone and dynamics of side chain. The torsion angles ϕ and Ψ were determined from the angular dependent 13C and 15N solid state NMR spectra for uniaxially oriented fiber samples. In addition, the characteristic side chain dynamics of Ser residue determined from solid state 2H NMR measurements was compared with those of Ala and Gly residues. 相似文献
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Hiroko Uegaki Masami Kamigaito Mitsuo Sawamoto 《Journal of polymer science. Part A, Polymer chemistry》1999,37(15):3003-3009
A zerovalent nickel complex, Ni(PPh3)4, induced living radical polymerization of methyl methacrylate (MMA) in conjunction with an organic bromide as an initiator [R–Br: CCl3Br, (CH3)2C(CO2Et)Br, (CH3)2C(COPh)Br] in the presence of Al(Oi-Pr)3 additive. The molecular weight distributions were narrow (M̄w/M̄n ∼ 1.2) throughout the reactions, and the number-average molecular weights (M̄n) increased in direct proportion to monomer conversion. In contrast, the polymers obtained with CCl4 in place of R–Br had broader MWDs (M̄w/M̄n > 2). The Al(Oi-Pr)3 additive should be added for the smooth polymerizations of MMA to occur, similarly to those with a divalent nickel bromide, NiBr2(PPh3)2. The Ni(PPh3)4-mediated living polymerization apparently proceeds via the activation of the C Br bond from the initiators R Br, assisted by the redox reaction of the complex between Ni(0) and Ni(I) species. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3003–3009, 1999 相似文献
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Dr. Chao Wan Gui Li Jiapei Wang Prof. Lixin Xu Prof. Dang-guo Cheng Prof. Fengqiu Chen Prof. Yusuke Asakura Dr. Yunqing Kang Prof. Yusuke Yamauchi 《Angewandte Chemie (International ed. in English)》2023,62(40):e202305371
Ammonia borane (AB) is a promising material for chemical H2 storage owing to its high H2 density (up to 19.6 wt %). However, the development of an efficient catalyst for driving H2 evolution through AB hydrolysis remains challenging. Therefore, a visible-light-driven strategy for generating H2 through AB hydrolysis was implemented in this study using Ni−Pt nanoparticles supported on phosphorus-doped TiO2 (Ni-Pt/P-TiO2) as photocatalysts. Through surface engineering, P-TiO2 was prepared by phytic-acid-assisted phosphorization and then employed as an ideal support for immobilizing Ni−Pt nanoparticles via a facile co-reduction strategy. Under visible-light irradiation at 283 K, Ni40Pt60/P-TiO2 exhibited improved recyclability and a high turnover frequency of 967.8 mol molPt−1 min−1. Characterization experiments and density functional theory calculations indicated that the enhanced performance of Ni40Pt60/P-TiO2 originated from a combination of the Ni−Pt alloying effect, the Mott–Schottky junction at the metal-semiconductor interface, and strong metal-support interactions. These findings not only underscore the benefits of utilizing multipronged effects to construct highly active AB-hydrolyzing catalysts, but also pave a path toward designing high-performance catalysts by surface engineering to modulate the electronic metal-support interactions for other visible-light-induced reactions. 相似文献
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