Advanced Materials Research Vols. 641-642

Abstract: In this paper, the ratio-dependent chemostat model with Holling-(n+1) type functional response is considered. The model develops the Monod model and the ratio-dependent model. By use of the Poincar -Bendixson theory we prove the existence of limit cycle. Detailed qualitative analysis about the global asymptotic stability of its equilibria is carried out by using the Lyapunov-LaSalle invariant principle and the method of Dulac criterion.

Abstract: L-3, 4-Dihydroxyphenylalanine(DOPA) has a unique catechol moiety found in adhesive proteins in marine organisms, such as mussels and polychaete, which results in strong adhesion in aquatic conditions. Conventional efforts incorporating DOPA into polymer is grafting methacrylate anhydride. For this reason, we synthesized the new catechol intermediate N-methacryloyl 3,4-dihydroxyl-phenylamine and analyzed the surface morphology and thermal stability of it.

Abstract: The antidiabetic activities of the extracts with different solvents and methods from Limonium bicolor Kuntze were investigated. It was found that all the extracts with ethanol, petroleum ether, EtOAc, n-BuOH and H₂O from the underground part of the plant possessed the α-Glucosidase inhibitory activity, and the fractions from the 80% ethanol extracts possessed strong activity. The extracts eluted with water from the 80% ethanol crude extract of the aerial part of the plant were inactive to α-Glucosidase inhibition, the other extracts from the aerial part all give potent α-Glucosidase inhibition activity.

Abstract: Lemonile is a new kind of spice. The new technology for synthesis of lemonile from citral by catalytic ammoxidation has been investigated. Experimental results showed the optimal synthetic conditions are as follows. The molar material ratio n(H₂O₂):n(Citral) is 3:1, solvent for the reaction is isopropanol, dosage of the catalyst CuCl is 3% (wt, calculated by citral), the drop-feeding temperature and time for hydrogen peroxide are 10 °C-14 °C and 3 hrs, respectively; after hydrogen peroxide being drop-fed into the reaction system, the reaction should be continued for 4 hrs. Lemonile yield is 91.2% and purity is 98.5% (detected by GC) under the optimal conditions. This new one-step liquid phase catalytic ammoxidation technology is a green synthesis way for lemonile. The structure of the product has been confirmed by GC-MS.

Abstract: Autotoxicity of aqueous extracts from roots, stems and leaves of flowering Chinese cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) were studied by hydroponic in different concentrations (0.5g/L, 2g/L, 5g/L). The results showed that in solution with aqueous extracts from roots, stems and leaves, the growth of flowering Chinese cabbage were inhibited, leaf chlorophyll content declined, photosynthesis rate were affected, activities of SOD, POD and CAT were changed, MDA concentration increased, thus cell membrane permeability of flowering Chinese cabbage was damaged. The autotoxicity of aqueous extracts in flowering Chinese cabbage increased with the extracts concentration increasing.

Abstract: A study on the kinetics of inhibitory effect of 4-hydroxy-3-methoxybenzoic acid on the monophenol- and diphenol-oxidation activity of mushroom tyrosinase has been carried out using enzymological kinetic analysis method in a Na2HPO4-NaH2PO4 buffer solution (pH=6.8) at 30 °C. The results show that 4-hydroxy-3-methoxybenzoic acid efficiently can inhibit both monophenol- and diphenol-oxidation activity of mushroom tyrosinase under experiment conditions. Concentrations of 4-hydroxy-3-methoxybenzoic acid leading to 50 % inhibition rate (IC50) on monophenol- and diphenol-oxidation activity were calculated to be 1.3 mmol/L and 2.6 mmol/L respectively, which are lower than that of arbutin (IC50 = 5.3 mmol/L for diphenol-oxidation activity). The presence of 4-hydroxy-3-methoxybenzoic acid also prolongs the lag period in oxidation of L-tyrosine via tyrosinase — A 4.7-minute lagging was observed in the presence of 4 mmol/L 4-hydroxy-3- methoxybenzoic acid, compared to a 1.1-minute lagging in the absence of inhibitor. The inhibition kinetics analyzed by Lineweaver-Burk plots found 4-hydroxy-3- methoxybenzoic acid to be a mixed-type inhibitor for the oxidation of L-DOPA, the equilibrium constants for inhibitor binding with free enzyme, KI , and with enzyme-substract complex, ＫIS, were 1.76 mmol/L and 8.57mmol/L respectively.

Abstract: To enhance enzymatic hydrolysis efficiency of the corn straw, a process microwave pretreatment of corn straw was optimized using response surface methodology (RSM). Estimated optimum parameters were as follows: water to corn straw ratio is 58:1, microwave power is 640w and processing time is 5 minutes. Under these conditions, a maximum enzyme hydrolysis ratio of corn straw (49.25%) after microwave pretreatment was reached.

Abstract: Soluble polysaccharide is a main bioactive composition of Cordyceps sinensis. To increase its antioxidant activity, 500 mg of submerged fermentation products of C. sinensis was incubated with 7.5 U or 375 U of cellulase in 50 mL of water at 50°C for 2 h. The content of soluble polysaccharide of submerged fermentation products of C. sinensis increased from 30.28% to 33.23~38.10%. At the same concentration, the DPPH free radicals scavenging capability and reducing power of cellulase-treated soluble polysaccharide were higher than those of untreated control.

Abstract: By using a new kind of single-beam normalized photo-acoustic tomography spectroscopy (PAS-CT) technology with non-damage detection, the photo-acoustic tomography spectroscopy, optical absorption properties and photosynthetic pigment content of the green and yellow leaves of Osmanthus fragrans were studied. The results show that: photo-acoustic tomography spectroscopy could be obtained from different chopping frequency and different sample position. The more photosynthetic pigment content the leaves of Osmanthus fragrans contains, the bigger optical absorption coefficient and the higher photosynthetic efficiency they have. In the research, we could find that the photosynthetic pigment content of the green leaves of Osmanthus fragrans is higher than that of the yellow ones. As a result, the optical absorption coefficient and the photosynthetic efficiency of the green ones are higher than the yellow ones. The photo-acoustic tomography spectroscopy technology could be a kind of non-damage detection to confirm the growth of trees.

Abstract: We screen the neutral protease enzyme used to hydrolysis, through scavenging effect of six enzymatic hydrolysate on O2-•. The hydrolysis of condition was optimized by response surface methodology on the basis of single factor experiments. The optimized condition was as follows: hydrolysis temperature 43.65 °C, pH 6.25, time 3.29h, and content of enzyme 3.0% (W/W). Under this condition, the O2-•scavenging rate of the hydrolyzate was up to 72.01%. The experimental results were 71.15%.