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排序方式: 共有400条查询结果,搜索用时 15 毫秒
31.
Lucas Montero De Espinosa Juan C. Ronda Marina Galià Virginia Cádiz Michael A.R. Meier 《Journal of polymer science. Part A, Polymer chemistry》2009,47(21):5760-5771
The acyclic diene metathesis (ADMET) polymerization of a phosphorus‐containing α,ω‐diene prepared from a plant oil derived building block is reported. Different ruthenium based metathesis catalysts and conditions were tested to optimize the ADMET polymerization of this monomer. Undecylenyl undecenoate was used as fully renewable comonomer to obtain polyesters with different phosphorus contents and to increase the renewable content of the final polymers. Copolymerization caused marked variations in the molecular weights leading to polyesters from 6 to 38 KDa. The effect of the ADMET polymerization temperature in the thermal properties of the copolymers was studied and their thermal degradation and flame retardant properties were evaluated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5760–5771, 2009 相似文献
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Indium nitrate and thiourea were used as the precursor solutions for preparing indium sulfide thin films using Chemical Spray Pyrolysis (CSP) technique. Films having various In/S ratios were characterized using X-Ray Diffraction (XRD), Energy Dispersive X-ray Analysis (EDX), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), optical absorption, transmission and photosensitivity measurements. Sample having In/S ratio 2/3 showed better crystallinity with band gap 2.66 eV. Depth profile of the sample also indicated the formation of indium sulfide. It was also observed that In/S ratio in the initial precursor solution determined the composition as well as electrical properties of the films. Maximum photosensitivity was observed for the sample prepared using solution having In/S ratio 2/4. 相似文献
34.
Three laccase temperature isoforms were isolated and purified to homogeneity from the xerophyte plant species Cereus pterogonus. This catalytically active protein exhibited an apparent molecular mass of 137 kDa, 90 kDa, and 43 kDa. Under reducing conditions the enzyme yielded a subunit molecular mass of 43 kDa alone, suggesting that the enzyme is a multimer of its subunits. The enzyme exhibited an optimum pH of 10 with 2,6-dimethoxyphenol used as a substrate. The 137 and 90 kDa forms yielded optimum activity at 90°C; whereas the 43 kDa molecular form yielded optimum activity at 60°C. The enzyme kinetic constant Km remained closely similar for all three enzyme forms, whereas Vmax varied by 25 % overall. The catalytic activity remained above its t1/2 value in excess of the 30 min denaturation assay period at 60°C and 90°C. These high-temperature isoforms of the plant laccase enzyme with alkaline pH optima can find great industrial use. 相似文献
35.
A primary flexure problem defined by Kirchhoff theory of plates in bending is considered. Significance of auxiliary function introduced earlier in the in-plane displacements in resolving Poisson-Kirchhoff's boundary conditions paradox is reexamined with reference to reported sixth order shear deformation theories, in particular, Reissner's theory and Hencky's theory. Sixth order modified Kirchhoff's theory is extended here to include shear deformations in the analysis. 相似文献
36.
E. Del Rio G. Lligadas J. C. Ronda M. Galià V. Cádiz 《Journal of polymer science. Part A, Polymer chemistry》2010,48(22):5009-5017
A series of poly(ether urethane) networks were synthesized from polyether polyols obtained by ionic‐coordinative polymerization of epoxidized methyl oleate (EMO) using 4,4′‐methylenebis(phenyl isocyanate) or l ‐lysine diisocyanate as coupling agents. Moreover, a variety of segmented poly(ether urethane) networks with different hard segment contents were obtained using 1,3‐propanediol as the chain extender. The materials were characterized by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical thermal analysis, and tensile properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
37.
Radical Compatibility with Nonaqueous Electrolytes and Its Impact on an All‐Organic Redox Flow Battery
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Dr. Xiaoliang Wei Dr. Wu Xu Dr. Jinhua Huang Dr. Lu Zhang Dr. Eric Walter Dr. Chad Lawrence Dr. M. Vijayakumar Dr. Wesley A. Henderson Dr. Tianbiao Liu Dr. Lelia Cosimbescu Dr. Bin Li Dr. Vincent Sprenkle Dr. Wei Wang 《Angewandte Chemie (International ed. in English)》2015,54(30):8684-8687
Nonaqueous redox flow batteries hold the promise of achieving higher energy density because of the broader voltage window than aqueous systems, but their current performance is limited by low redox material concentration, cell efficiency, cycling stability, and current density. We report a new nonaqueous all‐organic flow battery based on high concentrations of redox materials, which shows significant, comprehensive improvement in flow battery performance. A mechanistic electron spin resonance study reveals that the choice of supporting electrolytes greatly affects the chemical stability of the charged radical species especially the negative side radical anion, which dominates the cycling stability of these flow cells. This finding not only increases our fundamental understanding of performance degradation in flow batteries using radical‐based redox species, but also offers insights toward rational electrolyte optimization for improving the cycling stability of these flow batteries. 相似文献
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39.
G. R. Vijayakumar 《Graphs and Combinatorics》2011,27(1):143-148
A collection of nontrivial paths in a graph G is called a path pile of G, if every edge of G is on exactly one path and no two paths have a common internal vertex. The least number that can be the cardinality of a
path pile of G is called the path piling number of G. It can be shown that ε ≤ ν + η where ε, ν and η are respectively the size, the order and the path piling number of G. In this note we characterize structurally the class of all graphs for which the equality of this relation holds. 相似文献
40.
Chinnaswamy Thangavel Vijayakumar Rajendran Surender Kumaraswamy Rajakumar Sarfaraz Alam 《Journal of Thermal Analysis and Calorimetry》2011,103(2):693-699
The compound 2,2-bis[4-(4-maleimidophenoxy phenyl)]propane was prepared by the imidization of bisamic acid of 2,2-bis(4-aminophenoxy
phenyl)propane. Various nanoclays were blended with this bismaleimide and thermally cured. The structural characterization
of the synthesized materials and the thermal properties of the bismaleimide and their blends were investigated through FTIR,
1H and 13C NMR, differential scanning calorimetry and thermo gravimetric analysis. Among the various clays investigated, Cloisite 15A
shows strong influence on the cure exotherm of bismaleimide. Introduction of clay mineral into bismaleimide shifts the onset
of curing exotherm to higher temperature and is nearly 40 °C. The thermal stability of the clay loaded cured bismaleimide
increases and the presence of clay particles in the cured bismaleimide matrix enhances the char formation. 相似文献