Advanced Materials Research Vols. 550-553

Abstract: Polyethylene glycol (PEG) fixation has been proved to significantly decrease nonspecific protein adsorption on varied substrates. Here, a strategy of surface modification using two kinds of PEGs with different chain lengths was developed to improve the surface ability of protein resistance. We designed different reaction routes and investigated their reaction conditions. The amount of nonspecific protein adsorption on the substrates after modification was measured by UV-Vis spectrometry. The results showed that higher performance of protein resistance on the solid surface was acquired from the two-step modification than other methods. A competitive mechanism of reaction was proposed to elucidate the interaction between distinct PEGs on the substrates.

Abstract: Batch fermentations by Clostridium thermobutyricum ATCC49875 at various pH values ranging from 5.9 to 6.8 were investigated. Based on the analysis of the experimental results, a two-stage pH-shift control strategy was proposed, with the aim of improving the efficiency of butyric acid production. At the first 24 h, pH was controlled at 6.8 to obtain the higher μx, and subsequently pH 6.2 was used to maintain high μp to enhance the production of butyric acid. Compared to control group (those of constant pH operations), a fermentation process by using this control strategy for butyric acid production had a significant improvement on the maximal butyric acid (24.60 g/l vs. 20.06 g/l) and glucose conversion efficiency (49.20% vs. 46.33%). Fed-batch fermentation by using pH-shift control strategy was also applied to produce butyric acid; and the maximal butyric acid yield and glucose conversion efficiency reached 28.75 g/l and 47.92%, respectively. These results showed that pH-shift fermentation could serve as an excellent alternative to conventional butyric acid fermentation.

Abstract: Purpose To search for a purification method of Grifolan Synthase crude extract from the mycelium of Grifola frondosa and determine its molecular weight. Methods Grifolan Synthase crude extract from the mycelium of Grifola frondosa was purified by recrystallization and native-PAGE. The process is as follows: Grifolan Synthase crude extract was dissolved in buffer solution (pH7.0). 10ml Grifolan Synthase crude extract solution was mixed with ammonium sulfate slowly to the concentration of 60%, and then mixed with 3ml cooling acetone (refrigeration at -18 °C for 12 hours) slowly, after standing for 24 hours, centrifugated at 5000rpm for 10 minutes at 4°C. Material at the interface was collected and air-dried as higher purity Grifolan Synthase. The higher purity Grifolan Synthase was dispersed in the native-PAGE gel, and the active band of native-PAGE gel was cut down and broken by ultrasonic treatment for 1min, then centrifugated at 5000rpm for 10 minutes at 4°C, the supernatant was taken and mixed with ammonium sulfate slowly to the concentration of 60%, after 24 hours on standing, centrifugated at 12000rpm for 10 minutes at 4°C, the pellets was got and the purity was checked by SDS-PAGE. The molecular weight of Grifolan Synthase was determined by SDS polyacrylamide gel electrophoresis (SDS-PAGE). Results Grifolan Synthase purified by recrystallization and native-PAGE was checked to be a single band by SDS-PAGE. The data of molecular weight obtained by SDS-PAGE showed that the molecular weight of Grifolan Synthase was 55000Da. Conclusion A purification method of Grifolan Synthase crude extract from the mycelium of Grifola frondosa was researched out, and the molecular weight of grifolan synthase was studied in this paper. It can lay the foundation for the further study on the structure and function of Grifolan Synthase.

Abstract: A Rhizopus strain producing esterifying enzyme was isolated from Luzhou-flavor DaQu. It was preliminary identified as Rhizopus arrhizus. Through the research of the culture conditions of the strain producing esterifying enzyme, it was found that the enzyme activity could reach 7.91U/mL as 2% corn meal used as C source, 6% peptone used as N source, initial pH value was 6.0, and 72h culture with 150 r/min agitation at 30°C.

Abstract: The function of heparin (HEP) playing in the morphogenesis of calcium carbonate was studied by a biomimetic synthesis method. The results showed that HEP macromolecules induced the formation of calcite with exposed coarse polar {00.1} faces and poriferous surfaces with lasting duration of mineralization at different initial pHs. The vast amounts of carboxyl and sulfonic moieties of HEP macromolecules were suggested to contribute the formation of calcite special planes and the subsequent morphologies variations.

Abstract: By analysing the viscosity of formic acid SF solutions and CaCl2- C2H6O- H2O SF solutions realized the advantages of formic acid SF solutions compared with CaCl2- C2H6O- H2O SF solutions. Studing on the changs of SF structure through the WAXD spectra of original SF and SF powder by drying different concentration formic acid SF solvents.

Abstract: In this paper, using chemical degumming method on corn bract fiber degumming experiment, in order to find a more suitable degumming process of corn bracts and to realize the development and utilization of corn bract fiber. "Pre-oxygen pretreatment + Two scouring" chemical degumming method was used, and the optimal combination of process parameters was found out by using orthogonal experimental design method. Optimal pretreatment parameters: H2O2 6g/L, Pre-treatment time 30min, Temperature 40°C; Two Scouring optimal parameter combinations: NaOH 16g/L, Temperature 80 °C, Scouring time 150min.

Abstract: Two kinds of polyacrylamide(HPAM)-degrading bacteria S1, S2, which can use HPAM as only nitrogen source and the sole carbon source, were isolated from petroleum-contaminated soil of Daqing Oilfield. The bioremediation for treating petroleum contaminated soil by immobilized microorganisms can improve the effect on biodegradation for pollutants in oil fields and reduce the loss of bacteria. The degradation ability of five kinds of embedding immobilization methods on soil pollutant was investigated. The experimental results showed that the immobilized microbial granules, which used polyvinyl alcohols (PVA) and sodium alginate as coagulant, activated carbon as coagulant-support, exhibited good mechanical strength, operated easily, be not breakable and low cost. Experiments results showed that after treatment using this kind of immobilized microbial granules, the HPAM concentration declined from 500 mg•L^-1 to 102 mg•L^-1 in 48 hours. The degradation rate of HPAM reached 79.6%. At the same time crude oil content decreased from 733.21 mg•L^-1 to 9.5 mg•L^-1. These immobilized microbial granules can remove 98.7% oil from the petroleum-contaminated soil in 48 hours.

Abstract: In this study, polyester (PET) fiber and 304 stainless steel (SS) wires are twisted and then braided into multi-layer braids on a braiding machine, forming PET/SS composite braids. The braids form the artificial bone scaffold whose mechanical properties are tested and found to be acceptable and with good biocompatibility. However, scaffold made from polymer does not provide enough strength; thus, PET fibers are combined with SS wires to promote scaffold’s mechanical properties and reduce the stress shielding effect. According to the test results, the braid angle increases with an increase in the number of teeth on the braiding gear; by contrast, tensile strength increases with a decrease in tooth number. In particular, when the gear ratio of the take-up gear to the braid gear is 90:50, the resulting braids yield the optimum tensile strength.

Abstract: Emerging biorefinery technologies offer a sustainable alternative through the utilisation of carbohydrates to reduce our reliance on fossil fuels. Cellulose molecules consist of long chains of glucose molecules as do starch molecules, but have a differentstructural configuration. These structural characteristics plus the encapsulation by lignin makes cellulosic materials more difficult to hydrolyze than starchy materials. In recent years, treatment of lignocellulosic biomass with dilute acid has been primarily used as a means of hemicellulose hydrolysis and pretreatment for enzymatic hydrolysis of cellulose and a significant advancement has also been found by adding hydrochloric acid with catalyst dosage in saturated formic acid. In the present work, the hydrochloric acid concentration, temperature, the ratio of solid to liquid and reaction time were prepared for the fermentable sugars production. The obtained optimum conditions were: adding 4% hydrochloric acid in saturated formic acid solution, temperature of 105 °C, with a reaction time of 90 min, and the maximum glucose and reducing sugars production were 26.84 g/L% and 27.4%, respectively.