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【期刊论文】Toughness of Spider Silk at High and Low Temperatures**
邵正中, By Yong Yang, Xin Chen, Zhengzhong Shao, * Ping Zhou, David Porter, David p. Knight, Fritz, Vollath
Adv. Mater. 2005, 17, no.1 January 6,-0001,():
-1年11月30日
The outstanding strength and toughness of certain spider and lepidopteran silkst [1] has aroused considerable interest in recent years, [2] with research focusing primarily on the rela-tionship between molecular structure and mechanical proper-ties. [3] Environmental conditions such as ambient humidity, [4] acidity, [5] and UV radiation [6] a11 affect the mechanical proper-ties of native silks to some degre. [7] pronounced differences in mechanical properties were also observed when conditions such as the speed or temperature at spinning were varied [8] or when the silk was (or had been) submerged in solvents such as water, urea solution, or a range of alcohols, where it con-tracts in varying degrees. [9]
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邵正中, Jinrong Yao, Dahui Xiao, Xin Chen, Ping Zhou, Tongyin Yu, and Zhengzhong Shao *
Macromolecules 2003, 36, 7508-7512,-0001,():
-1年11月30日
With the step-growth polymerization of bis (oligopeptides) and diisocyanates, two silkproteinlike multiblock polymers (P1, P2), containing-(Ala)4-and-(GlyAlaGlyAla)-sequence derived from the crystalline region of spider dragline silk and silkworm (Bombyx mori) silk respectively, has been synthesized successfully. The intrinsic viscosities of P1 and P2 measured in dichloroacetic acid at 25℃ were 0.31 and 0.26dL/g. FT-IR, 13C CP/MAS NMR and WAXD measurements revealed the oligopeptide segments in these multiblock polymers could aggregate spontaneously into β-sheet structure in solid state. In addition, it was also found there were non-β-sheet structures in the synthetic polymers, which indicated such polymers had a solid-state structure similar to that of natural silks.
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【期刊论文】Structure and Behavior of Regenerated Spider Silk
邵正中, Zhengzhong Shao, *, †, § Fritz Vollrath, ‡, § Yong Yang, † and Hans C. Thøgersen┴
Macromolecules 2003, 36, 1157-1161,-0001,():
-1年11月30日
Molecule chains of spider silk protein readily self-assemble into ordered structure such as β-sheets when a filament is pulled away from dilute aqueous solution of spider major ampullate silk protein. There is no need to change the pH, the temperature, or the ionic strength of the solution to aid filament formation. Circular dichroism spectroscopy confirmed that the silk protein in such aqueous solution was initially in random coil formation but with time would transform to β-sheets; the process was temperature-dependent. Amino acid analysis showed that reassembled (regenerated) and native spider silks were similar in composition. The morphology and structure of the reassembled silk were investigated by scanning electron microscopy and Raman spectroscopy. The mechanical properties of the reassembled silk were studied in some detail. Our study indicates that reconstituted spider silk self-assembles into respectable filaments. However, it is clear that the spinning process is crucial for the desirable material properties of native silks.
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邵正中, Z. Shao, X. W. Hu, S. Frische, F. Vollrath *
Polymer 40(1999)4709-4711,-0001,():
-1年11月30日
Previous work has shown that dragline silk of Nephila madagascariensis is not homogeneous in cross-section. We report here that the core of Nephila edulis silk also contains extremely fine elongated, electron lucent domains. These domains may contribute to the exceptional tensile strength and toughness of this material by acting as stress concentration parts or (and) fluid-filled canaliculi. q1999 Elsevier Science Ltd. All rights reserved.
Biopolymer, Fibrous protein, Microstructure
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邵正中, Yuhong Yang, Zhengzhong Shao, * Xin Chen, and Ping Zhou
Biomacromolecules, Vol. 5, No.3, 2004,-0001,():
-1年11月30日
Fluorescence and circular dichroism spectroscopy were used to monitor the conformational transition of regenerated Bombyx mori silk fibroin (RSF) in aqueous solutions under different conditions. According to the analysis of fluorescence spectra using anilinonaphthalene-8-sulfonic acid magnesium salt (ANS) as an external probe, the destruction of the hydrophobic core prior to the secondary structure change suggests that this collapse may initiate the conformational transition from random coil to β-sheet for RSF. The temperature dependence of the structural changes of RSF, detected by both fluorescence spectroscopy and circular dichroism, shows a reversible process upon heating and recooling, with the midpoint around 45℃. The results also indicate that most of the tryptophan (Trp) residues contained in silk fibroin are concentrated on the surface of the unfolded protein. However, they will change their location in the highly ordered structure (e. g., becoming more homogeneous) with the conformational transition of silk fibroin. Moreover, our studies also suggest that the presence of water plays a crucial role during the structure changes of fibroin.
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