Effect of Chitosan with Different Molecular Weights on Postharvest Quality of Chinese Chive Scapes

[Objective] The purpose of this study was to determine the effect of chitosan with different molecular weights on quality and lignification of postharvest Chi- nese chive scapes （Allium tuberosum Rottler ex Sprengel）. [Method] Some physio- logical and biochemical indexes such as weight loss, decay index, opening rate of flowers, chlorophyll and ascorbic acid content, respiration rate, the activities of enzymes, lignin and cellulose content of Chinese chive scapes treated with three kinds of chitosan with different molecular weights were investigated during the room stor- age at 20 ℃ to simulate shelf life. [Result] The results showed that all the treat- ments of chitosan with different molecular weights significantly delayed weight loss, decay index and opening rate of flowers, maintained higher chlorophyll and ascorbic acid content, inhibited respiration rate, reduced the activities of enzymes phenylala- nine ammonia lyase, cinnamyl alcohol dehydrogenase and peroxidase, and retarded lignin and cellulose accumulation during the storage of Chinese chive scapes. However, high molecular weight chitosan has better preservation effect on Chinese chive scapes. [Conclusion] The results suggest that the coating treatment of high molecu- lar weight chitosan may be a promising technique to maintain postharvest quality of Chinese chive scapes.

The Technology Research of Anti-oxidation Peptide Preparation by Alkaline Protease Hydrolyzing Wheat Germ Meal

Wheat germ meal is the by production of oil extracting, and a great quantity of it has been wasted, thus the quantity of lost protein is great. In order to use wheat germ meal proteins adequately, wheat germ proteins were hydrolyzed to anti-oxidation peptides by using alkaline protease. Through the single factor analysis and regression analysis, the optimized experiment conditions of hydrolysising wheat germ meal to wheat germ peptides were enzymatic quantity 0.8%（w/w）, material to liquid ratio 1∶12.3, enzymolysis time 2.1 h. Under these conditions, the scavenging effect was 49.78%,the DH was 22% and peptides content in enzymatic hydrolysate was 1.9%（w/w）.By SDS-PAGE electrophoresis,the molecular weight range of wheat germ peptides were below 10 ku and most were between 4.54 and 5.63 ku.The wheat germ proteins could be used ful y and grain resources would be saved.

ZnO/SiO_2-modified rare-earth-metal ternary catalyst bearing quaternary ammonium salts for synthesis of high molecular weight poly (propylene carbonate)

A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene carbonate）（PPC）. In the presence of ZnO/SiO_2, the ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst presented higher activity for CO_2/PO copolymerization, as well as a higher molecular weight of polycarbonate, while maintaining the high carbonate content originating from the neat ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst. In the presence of QASs bearing different halide anions（F., Cl., and Br.）, the type of the halide anion had a strong influence on the activity of the catalyst for CO_2/PO alternating copolymerization. Only tetramethylammonium fluoride（TMAF） could promote the alternating copolymerization without increasing the by-product. Combined the ZnO/SiO_2 catalyst and TMAF, the catalytic activity for CO_2/PO polymerization increased dramatically compared to the basic ternary catalyst system. The improved catalyst system produced a polymer with a high carbonate unit level equivalent to that of the polycarbonate produced by the basic ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst system.

Deep venous thrombosis after gastrectomy for gastric carcinoma:A case report

The treatment of gastric carcinoma consists of neoadjuvant chemoradiation,partial gastrectomy,subtotal gastrectomy,total gastrectomy,extended resection,and postoperative chemotherapy.Currently,gastrectomy and extended lymphadenectomy is the optimal choice for late gastric carcinoma.Postoperative complications are common after total gastrectomy including hemorrhage,anastomotic leakage,f istula,and obstruction.However,deep venous thrombosis(DVT) is an uncommon complication after gastrectomy for gastric carcinoma.We describe a case of a 68-year-old female patient with DVT after gastrectomy for gastric carcinoma.The patient was treated with anticoagulants and thrombolytics and subjected to necessary laboratory monitoring.The patient recovered well after treatment and was symptom-free during a 3-mo follow-up.We conclude that correct diagnosis and treatment of DVT are crucial.

Product of the Schistosoma mansoni Glutathione Peroxidase Gene is a Selenium ContainingPhospholipid Hydroperoxide Glutathione Peroxidase (PHGPx) Sharing MolecularWeight and Substrate Specificity WithIts Mammalian Counterpart

In the blood fluke Schistosoma mansoni a functionally active, monomeric, phospholipid hydroperoxide glutathione peroxidase (PHGPx) has been purified and characterized. This enzyme contains a catalytically active selenocysteine. The protein has been shown to be the product of a cloned gene, previously referred to as a glutathione peroxidase gene. S. mansoni PHGPx has been found 5 times more abundant in female than in male worm extract. As in vertebrate PHGPx, homology alignment indicates that the residues involved in the glutathione binding by the tetrameric cellular glutathione peroxidase are mutated in the S. mansoni enzyme. Thus, this aspect appears a landmark of the PHGPx-type of glutathione peroxidases,which might be of functional relevance

0il bleed from elastomeric thermal silicone conductive pads

Oil bleed is a serious problem in elastomeric thermal silicone conductive pads. The components of the oil bleed and the effect of the silicone chemical parameters on the amount ofoil bleed have been determined. The main components of oil bleeds are the uncrosslinked silicones in the cured resins, which include the unreacted silicone materials and the macromolecular substances produced by the hydrosilylation reaction. Cured resins with a high crosslinking density and a high molecular weight of vinyl silicone residues had a lower amount of oil bleed. In addition, a low Si-H content also reduced the amount ofoil bleed.

Aqueous RAFT Polymerization of Acrylamide： A Convenient Method for Polyacrylamide with Narrow Molecular Weight Distribution

Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentation transfer （RAFT） agent. Linear increases in molecular weight with conversion and narrow molecular weight distribution were observed for polyacrylamide （PAM） throughout the polymerization. By this method, PAMs with controlled molecular weight （up to 1.0 ~ 106） and narrow molecular weight distribution （Mw/Mn 〈 1.2） were prepared. This study provides an effective method for synthesis of PAMs with narrow molecular weight distribution under environmentally friendly conditions.