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671.
Steady state viscosity and viscoelasticity of HMHEC solutions were studied. Viscosity increases with concentration due to a reinforcement of the micellar network. High shear rate viscosities are independent of temperature. Two relaxation processes were observed, the long one related to the lifetime of the hydrophobic junction and the short related to rapid Rouse-like relaxations of the free chains. When SDS is added, mixed micelles form that reinforce the network up to an optimum [SDS]/[HMHEC] ratio. Above this ratio, the micelles in excess isolate the polymer chains, the long relaxation process disappears and Rouse-like relaxations occur, corresponding to rapid movements of free chains. 相似文献
672.
673.
Dr. Wentao Xu Dr. Nikita Hanikel Dr. Kirill A. Lomachenko Dr. Cesare Atzori Dr. Alicia Lund Dr. Hao Lyu Zihui Zhou Prof. Dr. C. Austen Angell Prof. Dr. Omar M. Yaghi 《Angewandte Chemie (International ed. in English)》2023,62(16):e202300003
We report a synthetic strategy to link titanium-oxo (Ti-oxo) clusters into metal-organic framework (MOF) glasses with high porosity though the carboxylate linkage. A new series of MOF glasses was synthesized by evaporation of solution containing Ti-oxo clusters Ti16O16(OEt)32, linkers, and m-cresol. The formation of carboxylate linkages between the Ti-oxo clusters and the carboxylate linkers was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. The structural integrity of the Ti-oxo clusters within the glasses was evidenced by both X-ray absorption near edge structure (XANES) and 17O magic-angle spinning (MAS) NMR. After ligand exchange and activation, the fumarate-linked MOF glass, termed Ti-Fum, showed a N2 Brunauer–Emmett–Teller (BET) surface areas of 923 m2 g−1, nearly three times as high as the phenolate-linked MOF glass with the highest BET surface area prior to this report. 相似文献
674.
Side-Chain Chemistry Governs Hierarchical Order of Charge-Complementary β-sheet Peptide Coassemblies
Dr. Renjie Liu Xin Dong Dr. Dillon T. Seroski Dr. Bethsymarie Soto Morales Dr. Kong M. Wong Alicia S. Robang Lucas Melgar Prof. Thomas E. Angelini Prof. Anant K. Paravastu Prof. Carol K. Hall Prof. Gregory A. Hudalla 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314531
Self-assembly of proteinaceous biomolecules into functional materials with ordered structures that span length scales is common in nature yet remains a challenge with designer peptides under ambient conditions. This report demonstrates how charged side-chain chemistry affects the hierarchical co-assembly of a family of charge-complementary β-sheet-forming peptide pairs known as CATCH(X+/Y−) at physiologic pH and ionic strength in water. In a concentration-dependent manner, the CATCH(6K+) (Ac-KQKFKFKFKQK-Am) and CATCH(6D−) (Ac-DQDFDFDFDQD-Am) pair formed either β-sheet-rich microspheres or β-sheet-rich gels with a micron-scale plate-like morphology, which were not observed with other CATCH(X+/Y−) pairs. This hierarchical order was disrupted by replacing D with E, which increased fibril twisting. Replacing K with R, or mutating the N- and C-terminal amino acids in CATCH(6K+) and CATCH(6D−) to Qs, increased observed co-assembly kinetics, which also disrupted hierarchical order. Due to the ambient assembly conditions, active CATCH(6K+)-green fluorescent protein fusions could be incorporated into the β-sheet plates and microspheres formed by the CATCH(6K+/6D−) pair, demonstrating the potential to endow functionality. 相似文献
675.
M. Carmen Matías Alicia Larena M. De La Ulagares Orden Joaquín Martinez Urreaga 《Macromolecular Symposia》1995,94(1):273-282
The effect of glass fiber reinforcements on the curing behavior of unsaturated polyester commercial resins was investigated by Fourier transform infrared spectroscopy. Two different E-glass fibers and two commercial resins were employed. The results indicate that both the glass fiber content and the fiber size have a pronounced effect on the ultimate values of the styrene conversion. Some complications found in the infrared analysis of commercial resins are also presented. 相似文献