It is a challenge to degrade sulfated polysaccharides without stripping sulfate groups. In the present study, a photocatalytic method was applied to degrade fucoidan, a sulfated polysaccharide from brown algae. The degradation with varying addition amounts of H2O2 and TiO2 were monitored by high performance gel permeation chromatography (HPGPC) and thin layer chromatography (TLC), and fucoidan was efficiently degraded with 5% TiO2 and 0.95% H2O2. A comparison of the chemical compositions of 2 products obtained after 0.5 h and 3 h illumination, DF-0.5 (average Mw 90 kDa) and DF-3 (average Mw 3 kDa), respectively, with those of fucoidan indicates the photocatalytic degradation did not strip the sulfate groups, but reduced the galactose/fucose ratio. Moreover, 12 oligosaccharides in DF-3 were identified by HPLC-ESI-MSn and 10 of them were sulfated. In addition, DF-0.5 showed anticoagulant activity as strong as fucoidan while DF-3 could specifically prolong the activated partial thromboplastin time. All samples exerted inhibition effects on the intrinsic pathway FXII in a dose-dependent manner. Thus, photocatalytic degradation demonstrated the potential to prepare sulfated low-molecular-weight fucoidan with anticoagulant activity.
The microstructure of a multiphase NiAl ± 33 . 5Cr ± 0 . 5Zr intermetallic alloy was examined by SEM with energy dispersive spectroscopy and TEM. The tensile creep behaviour of the hot isostatically pressed NiAl ± 33 . 5Cr ± 0 . 5Zr alloy was studied. The results of the creep test indicated that all of the creep curves under the present test have similar characteristics: a short primary creep stage, a dominant tertiary creep stage, and nearly identical creep strains (~45%). The apparent stress exponent and the apparent activation energy were analysed and discussed. The mechanism of the creep deformation was also analysed by the observation of TEM.MST/5243
Based on the panel data of 34 cities in Northeast China, this paper uses fixed-effect model and quantile regression method to empirically test the influencing factors of industrial structure upgrading. The results show that the government has led the upgrading of the industrial structure in Northeast China, economic growth and investment in fixed assets has inhibitory effect on industrial structure upgrade, the level of opening to the outside world, the financial sector development and the increase of human capital in the northeast has obvious role in promoting industrial structure upgrade. The quantile regression results show that the coefficient of each factor are basically consistent with the estimated results of ordinary panel fixed effect model, which further verifies the robustness of the research conclusions in this paper.
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