Applied Mechanics and Materials Vol. 142

Abstract: Study of activated carbon (AC) activator modified type, bore temperature, the ratio of the response activity. Optimized modified conditions: activator of CuCl2, a temperature of 800 °C, the AC activator ratio of 1:1. AC carrier prepared by reaming modified copper catalyst activity than the non-reaming significantly increased activity in the evaluation of typical conditions, the methanol conversion rate of 34.6%, DMC selectivity was 96.4%, DMC space-time yield was 221.1g / (kgcat • h). CuCl2 activation of AC in the pore distribution of modified ratio of 98%, mainly between the 2 ~ 3nm. Pore ​​structure of the catalyst carrier has a significant effect on the activity, a larger proportion of the pore size distribution and pore size of about 2.5 nm in the AC carrier is conducive to the dispersion of active components and oxidative carbonylation catalytic activity increased.

Abstract: Using DFT (B3LYP) method, the 6-31G * ,6-311G ** ,6-311 + + G ** and cc-pvtz basis set level, through the CH₃ + H₂ → CH₄ + H reaction of the reactants, transition state and product geometry optimization show that: the base group selection mode on the stationary geometry has little effect; by B3LYP/6-31G * calculated barrier 39.61kJ/mol only difference with the experimental values ​​39.41kJ/mol 0.20 kJ / mol; analysis along the IRC that the HH bond breaking and CH bond formation is a coordinated manner, and in response there is a guide on ways to respond to the vibration mode, vibration mode, the range to guide reaction is s =- 0.57 ~ 0.60 (amu) 1 / 2 • bohr.

Abstract: Magnesium matrix composites are prepared with a hybrid optimizing metod here. Different SiC volume fractions, processing temperature and stirring time have different influence on tensile strength and elongation of SiC; but how to find out the satisfied treating parameters is an unavoidable question, a hybrid method is put out and experiments prove the effectiveness of research work.

Abstract: The effects of stocking density on various growth parameters and sex reversal in the rice field eel (Monopterus albus) were investigated by evaluating steroid hormone, the gonadosomatic index (GSI) and sex ratio. Fish (mean initial weight of 9.88 ± 0.70 g) were stocked to densities of 4, 20, 36, 52, 68, 84 or 100 fish/m2 in cages (2 m × 1 m × 1.5 m) in a pond, with five replicate cages for each density. Fish were fed for 420 days on a formulated isocaloric diet containing 40.22% crude protein and 12.86 MJ/kg. Serum E2 and T concentrations were determined by radioimmunoassays. There were no significant differences in final bodyweight (FBW) and daily weight gain (DWG) for fish in the groups containing less than 52 fish/m2, while FBW and DWG were significant lower in groups at 68 fish/m2 or more. Specific growth rate (SGR) differed significantly between the 84 and 100 fish/m2 groups compared with the 4, 20 and 36 fish/m2 groups. There was no significant difference in SGR in groups containing less than 84 fish/m2. There were no significant difference between the 4 and 20 fish/m2 groups in net yield (NY), but these groups did differ significantly from the other groups. The final condition factors of fish stocked at 84 or 100 fish/m2 were significantly lower than fish stocked at the other densities. E2 and T hormone concentrations declined as stocking density increased, while GSI values increased initially but then reduced with increasing stocking density. Female ratio and survival decreased with increasing stocking density. The proportion of male fish was significantly greater in the three highest stocking density groups. Therefore, high stocking density may promote sex change from female to male in M. albus.

Abstract: The aim of this study was to investigate the effects of exogenous melatonin on sex reversal in the rice eel (Monopterus albus). This was carried out by evaluating the estradiol (E2) and testosterone (T) concentrations, gonadosomatic index (GSI) and sex ratio. Fish (9.80 ± 1.20 g average initial weight; n = 3 per group) were fed with one of five practical diets containing 0 (control), 10, 30, 50 or 70 mg kg-1 dietary melatonin contents to apparent satiation for fifteen months. Serum E2 and T concentrations were determined by radio immunoassays. E2 and T concentrations, GSIs and survival rates significantly decreased with increased concentrations of exogenous melatonin. Fish fed 70 mg kg-1 of dietary melatonin showed significantly lower rates of E2, T, GSIs and survival ratio than those fed with lower melatonin concentrations or the control group. The shift of sex ratio towards more male and intersex fish was correlated with increasing dietary melatonin contents. Therefore, a high dosage of melatonin may inhibit gonadal development and promote sex change from female to male in M. albus.

Abstract: The non-uniform distribution of matric suction in the unsaturated soil has a great impact on the stability of the unsaturated soil foundation pit. By means of the strength reduction finite element method, the stability of the unsaturated soil foundation pit reinforced with the cement-mixed sheet pile wall was analyzed. The overall safety factor of the unsaturated soil foundation pit reinforced with the cement-mixed sheet pile wall is greatly reduced and the position of potential sliding surface goes upward with the gradually decreasing of matric suction. With the constant height of the cement-mixed sheet pile wall, the shallower the embedding depth of the cement-mixed sheet pile wall is, the smaller the safety factor of the foundation pit slope is. The results show that the safety factor of the overall stability of the unsaturated soil foundation pit decreases with the deep excavation and the gradually decreasing of the matric suction.

Abstract: Spartina alterniflora can be widely used for fodder, sewage treatment and as a substantial source of bioactive material. As an invader, it strongly disturbs the structure and function of native ecosystem in China. However, it is also a promising bio-energy source. We analyzed the potential of S. alterniflora as a bio-energy source, including the superiority at both temporal and spatial scales, advantages in high photosynthetic efficiency and high productivity. Meanwhile, its exploitation for biofuel production was introduced.