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排序方式: 共有203条查询结果,搜索用时 31 毫秒
81.
Fathima NN Suresh R Rao JR Nair BU Ramasami T 《Colloids and surfaces. B, Biointerfaces》2008,62(1):11-16
Research on the effect of UV radiation on stabilized collagen is an area of potential interest owing to the fact that collagen is an important biomaterial finding immense use in various fields. In this present study, effect of UV irradiation on collagen stabilized using chromium(III) has been studied. The physical and optical properties affected by UV irradiation have been detailed. Viscosity measurements have shown that chromium(III) treated collagen has better stability against UV radiation than native collagen. Circular dichroic studies indicate that increase in concentration of chromium(III) does not affect the conformation of collagen however, the duration of irradiation has profound impact on the conformation of collagen. The fluorescence intensity of native collagen has been found to decrease more than that of chromium(III) treated collagen. The difference absorption spectra also shows that chromium(III) treatment brings about more stability to collagen against UV irradiation. 相似文献
82.
Emulsion polymerization of styrene/vinyl acetate/methyl methacrylate with butyl acrylate, acrylic acid and acrylamide is investigated using conventional and polymerizable surfactants. The effect of different surfactants on the water resistance, adhesion and surface properties of the polymer films was studied. The performance of films obtained from latexes using conventional surfactants is compared with that of latexes using polymerizable surfactants. The study showed that polymerizable surfactants are bound to the polymer backbone in such a way that their migration to film surfaces during drying is inhibited which helps in achieving better water resistivity with good adhesive performance. 相似文献
83.
A Highly Stable Copper‐Based Catalyst for Clarifying the Catalytic Roles of Cu0 and Cu+ Species in Methanol Dehydrogenation
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Huanhuan Yang Dr. Yanyan Chen Dr. Xiaojing Cui Guofu Wang Youliang Cen Dr. Tiansheng Deng Wenjun Yan Jie Gao Dr. Shanhui Zhu Prof. Unni Olsbye Prof. Jianguo Wang Prof. Weibin Fan 《Angewandte Chemie (International ed. in English)》2018,57(7):1836-1840
Identification of the active copper species, and further illustration of the catalytic mechanism of Cu‐based catalysts is still a challenge because of the mobility and evolution of Cu0 and Cu+ species in the reaction process. Thus, an unprecedentedly stable Cu‐based catalyst was prepared by uniformly embedding Cu nanoparticles in a mesoporous silica shell allowing clarification of the catalytic roles of Cu0 and Cu+ in the dehydrogenation of methanol to methyl formate by combining isotope‐labeling experiment, in situ spectroscopy, and DFT calculations. It is shown that Cu0 sites promote the cleavage of the O?H bond in methanol and of the C?H bond in the reaction intermediates CH3O and H2COOCH3 which is formed from CH3O and HCHO, whereas Cu+ sites cause rapid decomposition of formaldehyde generated on the Cu0 sites into CO and H2. 相似文献
84.
C. Jayaram 《代数通讯》2018,46(5):2205-2217
In this paper, we introduce von Neumann regular modules and give many characterizations of von Neumann regular modules. Further, we investigate the relations between von Neumann regular modules and other classical modules. Finally, we characterize Noetherian von Neumann regular modules. 相似文献
85.
Reacting flow fields are often subject to unsteadiness due to flow, reaction, diffusion, and acoustics. Further, flames can also exhibit inherent unsteadiness caused by various intrinsic instabilities. Interaction between various unsteady processes across multiple scales often makes combustion dynamics complex. Characterizing such complex dynamics is essential to ensure the safe and reliable operation of high efficiency combustion systems. Tools from nonlinear dynamics and complex systems theory provide new perspectives to analyze and interpret the data from real systems. They could also provide new ways of monitoring and controlling combustion systems. We discuss recent advances in studying unsteady combustion dynamics using the tools from dynamical systems theory and complex systems theory. We cover a range of problems involving unsteady combustion such as thermoacoustic instability, flame blowout, fire propagation, reaction chemistry and flow flame interaction. 相似文献
86.
87.
Sangeetha S Sathyaraj G Muthamilselvan D Vaidyanathan VG Nair BU 《Dalton transactions (Cambridge, England : 2003)》2012,41(19):5769-5773
We report two fluorophores with open coordination sites for specific sensing of Ni(2+) and Cu(2+) ions via a simple synthetic route. The fluorescence activity was completely quenched on coordination of the metal ions with the phenanthroline ring present in the fluorophore as is clearly evident from the photophysical studies. 相似文献
88.
89.
Madhavan Unni PK 《The Journal of chemical physics》2006,124(12):124510
We report preliminary experiments on the ternary-liquid mixture, methyl ethyl ketone (MEK)+water (W)+secondary butyl alcohol (sBA)--a promising system for the realization of the quadruple critical point (QCP). The unusual tunnel-shaped phase diagram shown by this system is characterized and visualized by us in the form of a prismatic phase diagram. Light-scattering experiments reveal that (MEK+W+sBA) shows near three-dimensional-Ising type of critical behavior near the lower critical solution temperatures, with the susceptibility exponent (gamma) in the range of 1.217< or =gamma< or =1.246. The correlation length amplitudes (xio) and the critical exponent (nu) of the correlation length (xi) are in the ranges of 3.536< or =xio < or =4.611 A and 0.619< or =nu< or =0.633, respectively. An analysis in terms of the effective susceptibility exponent (gammaeff) shows that the critical behavior is of the Ising type for MEK concentrations in the ranges of 0.1000< or =X< or =0.1250 and X> or =0.3000. But, for the intermediate range of 0.1750< or =X<0.3000, the system shows a tendency towards mean-field type of critical behavior. The advantages of the system (MEK+W+sBA) over the system (3-methylpyridine+water+heavy water+potassium Iodide) for the realization of a QCP are outlined. 相似文献
90.