溶胶-凝胶TiO_2-SiO_2二元系统的结晶特征

采用XRD和DTA -TG等方法研究了溶胶 -凝胶法制备的TiO2 -SiO2 二元系统的结晶相 ,锐钛矿 -金红石晶相转变温度与组成的关系 ,锐钛矿微晶尺寸与组成的关系 。

Production of Amylase Enzyme through Solid State Fermentation by Aspergillus niger

Traditionally, coconut dregs will be used as animal feed after the extraction of coconut oil and coconut milk from the copra. This study was carried out to discover the commercial value of coconut dregs as a solid substrate in the production of amylase through solid state fermentation （SSF） since this agro-waste is fairly rich in nutrients, providing the necessary nutrients supplementation for better microbial activity to produce enzymes. In this study, amylase is to be produced from coconut dregs by Aspergillus niger through solid state fermentation （SSF）. Three parameters were covered, which are incubation time, initial moisture content of substrate and inoculum sizes. SSF was carried out by using incubator at 37 ~C to test for enzyme activity at these following parameters： incubation time： 24, 48, 72, 96 and 120 hours; substrate moisture content： 64, 66, 68, 70 and 72% （w/w）; inoculum sizes： 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mL spore suspension （5.5 × 10^6 spores/mL）. Enzyme activities were measured through the estimation of liberated reducing sugars after the assay of amylase enzyme by using DNS （3, 5 dinitrosalicylic acid） method. Highest enzyme activities were obtained at these following parameters： incubation time： 72 hours （31.76 U/gds）; initial moisture content ofsubstrate： 66% （26.66 U / gds） and inoculum sizes： 2.0 mL （30.56 U/gds）.

Bienzyme system immobilized in biomimetic silica for application in antifouling coatings

Antifouling coatings are used extensively on vessels and underwater structures. Conventional antifouling coatings contain toxic biocides and heavy metals, which may induce unwanted adverse effects such as toxicity to non-target organisms, imposex in gastropods and increased multiresistance among bacteria. Therefore,enzyme-based coatings could be a new alternative solution. A H2O2-producing bienzyme system was developed in this study. H2O2 can be produced from starch by the cooperation of α-amylase and glucose oxidase, which promotes the hydrolysis of polymeric chain and oxidizes the glucose to produce H2O2, respectively. The encapsulated bienzyme(A-G@BS) exhibits enhanced stabilities of thermal, pH, recycling and tolerance of xylene. The A-G@BScontaining coating releases H2O2 at rates exceeding a target of 36 nmol·cm-2·d-1for 90 days in a laboratory assay. The results demonstrate that the method is a promising coating technology for entrapping active enzymes,presenting an interesting avenue for enzyme-based antifouling solutions.

Facile Synthesis of Mesoporous γ-Alumina using Starch as Template

Mesoporous alumina was prepared by using starch as the structure-directing template in an aqueous system. The resultant samples were characterized by using different methods such as the X-ray diffractometry,the transmission electron microscopy,the nitrogen adsorption-desorption analysis and the solid MAS NMR. The results showed that the prepared mesoporous γ-alumina had high surface area and uniform pore size distribution,and its specific surface area and the pore size could be tuned by changing the pH value of the starting solution.

Kinetic Parameter of Alfa-amylase and Glucoamylase Enzymatic Reaction on the Glucose Yield from Hydrolyzed Processes of Tapioca Solid Waste

The increasing of tapioca production nowadays effected the production of waste. The waste of tapioca industries consists of two kinds, which were liquid waste and solid waste. Further more, tapioca solid waste treatment was ineffective. Weather solid waste produced from the extraction process still contains high concentration of starch that can be used to produce high quality product, for example, bio ethanol or other alternative energy sources. Objective of these experimental work was utilizing solid waste of tapioca industries and looking for the exactly composition of n-amylase and gluco-amylase enzymes on the hydrolysis processes of the solid waste of tapioca. The exact composition from both enzymes can be expected to increase the yield of glucose. Variables of cx-amylase enzyme for this research were 0.3% （w/w） and 0.5% （w/w） with liquefaction time were 1 hour and 1.5 hours, and variables of glucoamylase enzyme were 0.3% （w/w） and 0.5% （w/w）. To achieve these goals, the experimental work was held in laboratory scale with batch process. Firstly, tapioca solid waste was pretreated at 90 ~C and added u-amylase enzyme for 1 hour and 1.5 hours （variable of liquefaction time）. Then, substrate was cooled down to 60 ~C added with proposed variables of glucoamylase enzyme, and was analysed 24 hours after added. This experiment showed the best ratio between a-amylase and glucoamylase enzymes 0.5%：0.5% with 1 hour of liquefaction time. The highest glucose reaches 8.468% and yields 0.892 （g glucose/g starch） with starch conversion of 59.94%. KM = 0.0468 g/mL and rmax = 0.311 g/mL·h,

Stereoselective interactions of chiral dipeptides on amylose based chiral stationary phases

Dipeptides are stereo-specifically involved in several biological functions that are challenging to separate enantiomerically. Elution order of enantiomers is an important issue in chiral chromatography. Amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase(CSP) is the best and most-widely-used CSP in chiral separations, but experimental data of enantiomeric separation of dipeptides on this CSP is lacking. Simulation studies were conducted to determine the order of elution and the chiral recognition mechanism of didpetides on this CSP. Results indicated that the docking energy of SR-enantiomers were higher than SS-antipodes. The range of docking energies for SR-enantiomers was -7.44 to -5.92 kcal/mol with CSP, but -7.15 to -5.87 kcal/mol for SS-stereoisomers. Therefore it is predicted that SS-enantiomer will elute first, followed by SR-antipode. Furthermore, hydrogen bondings, van der Waal's interactions and electrostatic interactions were observed among SR- and SSenantiomers and chiral grooves of CSP. The number of hydrogen bonds was one in each enantiomer binding except S-Ala-R-Tyr, which contained two hydrogen bonds. No hydrogen bond was found in S-Ala-R-Trp, S-Leu-S-Trp, and S-Leu-S-Tyr dipeptides bindings. The chiral recognition mechanisms dictate different strengths of stereoselective bindings of the enantiomers on CSP.