Applied Mechanics and Materials Vol. 618

Abstract: Kefir is a kind of fermented milk that is produced by inoculating Kefir grains into milk, mainly consisting of bacteria and yeasts. Bacillus and their metabolites also have found some biotechnological applications in many aspects. The aim of the present study was to evaluate the mixed fermentation conditions by kefir and Bacillus. The results showed that kefir and Bacillus could be mixed fermentation, the suggested optimum fermentation conditions are the following: inoculum size was 4 mL of mixed fermentation agent for per 100 mL medium, the ratio to kefir and Bacillus is 2:1, fermentation temperature of 28 °C and fermentation time of 20 h. Under the optimum fermentation conditions, the viable cell counts of Lactic acid bacteria, yeast and Bacillus could above 1.0×10¹¹, 4.0×10¹⁰, and 2.0×10⁹ CFU/mL respectively. After freeze-dried, by adding 10 % ( w/v ) skim milk, 3 % ( w/v ) glycerinum, 3 % trehalose and 1 % ( w/v ) Monosodium glutamate as for cryoprotectant, the viable cell counts could still above 10⁷ CFU/mL after 6 month.

Abstract: Golden Guanyin tea from Lishui city, Zhejiang province, is a new variety of Oolong tea with special aromas. To analysis the aroma compounds, two sample preparation methods of tea grinding and water distillation were carried out, then the tea aromas and amino acids were detected. The main aroma compounds were of dimethyl sulfide, butanal, ethyl acetate, butanedial and cyclobutene by the grinding method, as for the distillation method, the aroma compounds detected were of benzeneacetaldehyde, phenylethyl alcohol, benzyl nitrile, Geraniol, indole, cyclopentene, phenylethyl butyrate, nerolidol, methyl jasmonate, 2,2'-dipyridylamine, benzenedicarboxylic acid, cyclopentaneacetic acid, methyl jasmonate ester, dibutyl phthalate and phytol. Golden Guanyin tea samples had 16 kind amino acids, in which glutamic acid and leucine were of 0.047 and 0.041 mg/mL, respectively, and the minimum ones were of cysteine and methionine in concentration of 0.004 mg/mL. The results will be helpful in the quality improvement and production of the new Golden Guanyin tea.

Abstract: The gasification of straw stalk in CO₂ environment was studied by isothermal thermogravimetric analysis. The characteristics of rice straw and maize stalk gasification at different temperatures were examined under CO₂ atmosphere. The relationship between reaction time and carbon conversion of two biomass chars was analyzed by the random pore model (RPM), and compared with the simulation of the shrinking core reaction model (SCRM). The results show that the random pore model is better to predict the experimental data at different temperatures. This means that the characteristics of pore structure for the influence of biomass chars gasification is well reflected by parameter ψ used in RPM. It indicates that the RPM can be applied to the comprehensive simulation of biomass chars gasification in CO₂ environment.

Abstract: In this paper, two calcined Zhejiang diatomite and Jilin diatomite were modified by organic amine, polyethylene glycol, organocationic ions, organofunction group and metallic ions to adsorption and immobilize enzyme, the different organo-function group and metallic ions lead to the capacity of adsorptive enzyme changing with the variation of IEP value.

Abstract: The adsorption and desorption properties of Astragalus Polysaccharide (APS) (70% content) on Macroporous resins including X-5, AB-8 and D101 have been compared. APS solutions of different concentrations were tested to find a suitable sample concentration on the macroporous resins. According to our test results, AB-8 performs better than other resins. The adsorption capacity and desorption rate are 41.73mg/ml and 83.74%, higher adsorption speed for APS. Column chromatograph with AB-8 resin was used for the purification test, the sample concentration of APS is 20mg/ml, the purity of APS can reach 94.68%.

Abstract: Proteases have diverse applications in a wide variety of industries, such as in detergent, leather, food, pharmaceutical and silk. The extracellular cold-active protease was purified from the psychrotrophic bacterium Serratia sp. WJ39 from a meat factory. The protease was cold-active with a molecular mass of 47.6 kDa estimated on SDS-PAGE. It showed an optimal activity at pH of 8 and was stable at pH 6 to 10, while its optimal temperature was 37°C and it was stable at 0-25°C, even remained 35% residual activity at 0°C. The protease was totally inhibited by PMSF which was telling that the purified enzyme was a serine protease. The properties like moderate thermostability, activity in a broad pH range and resistance to metal ions make this enzyme a suitable candidate for the possible use in food and leather industry.

Abstract: The polyanion of copolymer poly (2-methacryloyloxyethyl phosphorylcholine-co-methacrylic acid) (PMA30) was synthesized by free radical polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and methacrylic acid (MA). The synthesized PMA30 was assembled on chitosan (CS) surfaces formation of chitosan nanoparticles by polyionic complex. The chitosan nanoparticle was prepared using methacrylic acid (MA), 2-methacryloyloxyethyl phosphorylcholine (MPC) by template polymerization. The size distribution and structure properties of chitosan nanoparticles were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), transmission electron microscopy (TEM) and zeta potential. These results show that a cell outer membrane mimetic surface was formed on the chitosan nanoparticles, which provides an effective way to improve the biocompatibility of chitosan nanoparticles.

Abstract: The ecotoxicological effects of Zn²⁺ on germination and early seedling growth of six pulses were investigated. Seeds of these plants were exposed to seven different concentrations of Zn (0, 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4 mM). The results indicated that root growth and shoot elongation of six pulse plants were more sensitive than seed germination and dry weight for measurement of the toxic of Zn²⁺ pollutions. Different species show different levels of tolerance to Zn²⁺ pollution. Vigna radiate and Lathyrus odoratus are the most sensitive to Zn²⁺, their germination percentage, root growth, shoot elongation and dry weight were significantly lower than other tested species, by contrast, Glycine max and Dumasia villosa are the most resist species, their germination and seedling growth almost were not influenced by Zn²⁺ pollution significantly comparing the control. There were significantly negatively correlations between seedling growth and increasing concentration of Zn²⁺ for Glycine max, Lathyrus odoratus and Dumasia villosa. The significantly negative correlations between germination and increasing concentration of Zn²⁺ were show for Lathyrus odoratus.

Abstract: Study the Chinese Morus from the aspect of pollen morphology of 25 Chinese Morus plants of 10 species and 1 variety were observed using scanning electron microscopy (SEM). Results showed the differences to be mainly in pollen size, aperture size, P/E value and columellae structure.Supported the conclusion that Morus bombycis is a species level unit but Morus mizuho, Morus atropurpurea, and Morus multicaulis are not, the conclusion that Morus atropurpurea, Morus multicaulis, Morus alba, and Morus macroura are initial forms, and that Morus mongolica, Morus mongolica var. diabolica, Morus bombycis, and Morus australis are later forms.

Abstract: Lucaena (Leucaena leucocephala) is a valuable fodder tree, but it contains high contents of anti-nutritional factors, such as mimosine and tannins. The present study investigated the silage fermentation characteristics and ensiling effects on the degradation of mimosine and tannins of leucaena. Mimosine and tannins gradually reduced during ensiling, and sucrose and lactic acid bacteria (LAB) addition promoted their degradation. The highest degradation rate of mimosine was 49.0% in sucrose treatment and the lowest was 25.5% in the control. The highest degradation rate of tannins was 54.7% in the combined treatment of sucrose and LAB and the lowest was 40% in the control. The degradation rates of mimosine and tannins had negative correlation with the pH value and had positive correlation with lactic acid content in silage.