Advanced Materials Research Vols. 396-398

Abstract: In order to verify the properties of Konjac-κ-Carrageenan mixed gel, some effects were studied in this paper, including κ-Carrageenan-Konjac on their mixtures viscosity, temperature, heating time, concentration, storage temperature and time, KCl, CaCl2 and NaCl concentration in storage condition. The results showed that great synergism interaction existed among κ-Carrageenan and Konjac gum (such as viscosity and strength) for the action of molecular power. Moreover, the suitable conditions of gelation formation were mixed gel concentration 1.0%, 80°C water for 30 minutes, and then at room temperature for 6h, storage temperature (refrigeration, -5～18°C), KCl concentration 0.1%, CaCl2 concentration 0.1%～0.4% and NaCl concentration 0.6%～0.8%. These results could be theoretical reference for mixed gel application in food industry.

Abstract: Poly(styrene-co-maleic anhydride) nanofibers with a uniform diameter of about 400 nm were prepared by eletrospinning a solution containing 50 % (w/v) polymer and 1% (w/v) LiCl, 25 cm gap between jection needle tip and collector, a flow rate of 200 L/h, and an applied voltage of 24 kV. β-D-galactosidase was immobilized to the electrospun nanofibers and subsequently used for synthesizing hexyl-galactoside, an important nonionic surfactants, by catalyzing the transgalactosylation reaction between hexanol and lactose. Co-electrospun LiCl was found leading to a significant enhancement in the enzyme loading and activity of the immobilized β-D-galactosidase compared to nanofiber without LiCl. After 7 reusing cycles at 37oC, the immobilized enzyme retained about 33% of its original activity.

Abstract: In the present study, we examined resveratrol(RES)extracted from Polygonum cuspidatum on antioxidative effects in the senescence-accelerated mouse (SAM). We fed resveratrol to young adult SAM mice at doses of 25,50,100mg/(kg•bw) in their standard powder diet for 8-week. The body weight, organ weights and oxidation products of malondialdehyde (MDA) in the liver of the SAM were determined. The results showed that the SAM mice were no dose-related change in either body weight or organ weights, the amount of MDA declined distinctly in the mouse liver. In conclusion, resveratrol may have an antioxidant effect.

Abstract: This study is focused on the effects of the amount of initiator (potassium persulfate, KPS), monomer (styrene, St), emulsifiers, and temperature on the rate of polymerization. The experiment results show that the rate of polymerization is: Rp=K[KPS]1.374[St]1.479[S]0.875, and the apparent activation energy of polymerization is 94.64 kJ/mol.

Abstract: An experiment was carried out using rice straw pretreated with 2% diluted NaOH at 28 °C for 24 h followed by a combination of commercial reagents of xylanase (Pentopan) and cellulase (Primafast 200), with the latter either purified by affinity adsorption or unpurified, for enzymatic saccharification of the pretreated rice straw. Significant synergistic effects of the enzyme combinations were observed in the released amounts of reducing sugar, glucose and xylose at a lower loading of purified Primafast 200. The synergy was shown to be the result of interaction between cellulase and xylanase. Moreover, the enzymatic performance of unpurified Primafast 200 can be also improved by the addition of Pentopan, with greater synergistic effect at 50 °C rather than at 40 °C. Sugars released by mixed enzymes treatment were more than that using unpurified Primafast 200 alone in the whole hydrolysis course, however, the hydrolysis rate superiority of mixed enzymes was mainly observed during the first 6 hours. Application of the synergistic effect between cellulase and xylanase can improve the hydrolysis efficiency and reduce the cost of enzymatic saccharification of mild alkaline pretreated rice straw.

Abstract: A fresh fish swim bladder was used to extract protein with ultrasonic treatment technology. The coomassie brilliant blue G-250 was used to determine the protein content. Effects of ultrasonic power, duty cycle and pH of extraction solution on the extraction rate of proteins were investigated in this paper. The conditions of extracting protein from swim bladder by ultrasonic treatment were optimized by orthogonal experiments. The results indicated that the optimized conditions were ultrasonic power 125W, duty cycle 70%, and the pH of solution 1.0 respectively. This provided a basis for the development of application of ultrasonic extraction technology in the processing of fish swim bladder.

Abstract: Adenine Arabinoside were prepared from Ara-U and adenine using whole cells of Enterobacter aerogenes HXY2222. After incubated for 16h, 10% wet cells was added to the reaction mixture, containing 10mM AraU and adenine. The transarabinosylation reaction was carried out at 60°C, in pH 7.5 phosphate buffer, for 30h, and the yield was achieved 83%, based on the molar ratio of both substrates. When the reaction was carried out with 30mM AraU and adenine, the yield of AraA droped significantly due to the low solubility of adeine. 20%~25% (v/v) DMSO were added into the reaction mixture, and a yield of 77% was achieved.

Abstract: The styrene-ethylene/butylene-styrene/polystyrene (SEBS/PS) blends were prepared by melt blending. The mechanical properties of PS/SEBS blends were influenced by the increase of SEBS contents. When the content of SEBS increased to 13 wt%, the impact strength of SEBS/PS blends boosted the maximum value. Young’s modulus and tensile strength of SEBS/PS blends decreased with the increase of SEBS. The fracture surfaces obtained during Izod impact resistance tests were obtained by scanning electron microscopy (SEM). The results indicated that the number of particles of SEBS dispersed in PS matrix. The diameters of particles of SEBS were about 1.5-3 µm. SEBS/PS blends absorbed more energy than pure PS during impact resistance tests.

Abstract: Scanning Electron Microscope (SEM) was used to scan the surfaces of 9 kinds of food packaging paper, and the surface porosity of them was analyzed according to fractaltheory. To study the relationships between surface porosity and the air permeability of the paper samples, Schopper air permeability tester was used to test the air permeability of the samples. By fitting experimental curve, the relationships between the surface porosity and air permeability were obtained. It demonstrated that the fitting curve described the profile of the experimental values very well and the air permeability depends exponentially on surface porosity over a large range of porosity and the fitting curve equation is Ps=1.132e^15.89A.

Abstract: In order to find substrate specificity and enantioselectivity of ketoreductase domain (EryKR1) in the first module of polyketide synthase from Saccharopolyspora erythraea, the whole cells of recombinant Escherichia coli BL21 (pET-eryKR1)2 harboring eryKR1 gene fermented with different kinds of cyclohexanone derivatives such as methylcyclohexanone and cyclohexanedione. Gas Chromatography (GC) or Gas Chromatography Mass Spectrum (GC-MS) analyses of these ferments indicate that when the recombinant cells were employed as biocatalysts, only one carbonyl of 1,2-cyclohexanedione and 1,4-cyclohexanedione could be reduced with the conversion rate 20.44% and 6.03%, respectively. In addition, 2-methylcyclohexanone and 3-methylcyclohexanone except 4-methylcyclohexanone could be significantly turned over by the recombinant cells to their corresponding cis-methylcyclohexanols, of which the conversion rate of 40 mM 2-methylcyclohexanone was 12.2% and enantiomeric excess of cis-2-methylcyclohexanol was 57.98%, and the conversion rate of 10 mM 3-methylcyclohexanone was 38.26% and enantiomeric excess of cis-3-methylcyclohexanol was 53.9%. Furthermore, the unexpected reduction of 1,2-cyclohexanedione and 2-chlorocyclohexanone by the control E.coli BL21 (pET-28a) reveals that the attracting electron effect induced by the carbonyl or chlorin group in their ortho position could make some NAD(P)H-dependent oxo-reductase except EryKR1 domain within the recombinants reduce the carbonyl of 1,2-cyclohexanedione and 2-chlorocyclohexanone. Therefore, it is concluded that 1,4-cyclohexanedione, 2-methylcyclohexanone and 3-methylcyclohexanone except 1,3-cyclohexanedione and 4-methylcyclohexanone are accepted substrates of EryKR1 domain which takes on a certain biocatalyst activity and stereospecificity.