Applied Mechanics and Materials Vols. 675-677

Abstract: The mechanical behaviors of dissimilar metal weld SA508-52M-316L in several environments were investigated by using tensile tests with smooth specimens, focusing on the behavior of SA508-52M weld part during slow strain rates testing (SSRT) at 290°C in nitrogen gas and in simulated primary water at different electrode potentials. The mechanical properties at room temperature of main materials were obtained first. When tested at 290°C, the weld exhibited characteristics of dynamic strain ageing (DSA), which was more significant when strain rate was decreased from 1x10^-6 (1/s) to 3.1 x10^-7 (1/s). When tested in the water at the potentials from-720 to +200mV(SHE) , SA508-52M specimens showed the mechanical behaviors almost the same as that in nitrogen gas, with ductile failure happened in the 52M bulk weld metal. When the potential was raised to +300 and +400mV(SHE), brittle failure of stress corrosion cracking (SCC) took place around the interface, causing the significant drop of elongation and reduction in area.

Abstract: This article does some research on SiC-W composite material. Getting the material with SPS, the micro-structure was observed. The micro-structure of SiC is mainly lamellar structure and the Tungsten did not infiltrate the SiC. Via mechanics performance test of SiC-W, we found although both SiC and SiC-W show the characters of brittle material, but the Tungsten mixing can improve the toughness in certain level.

Abstract: Aquatic macrophytes are of significant importance for polluted water restoration.This paper reviews current research progress of stress factors for aquatic macrophytes growth and analyzes existing problems. Factors including nutritive salt, suspended sediments and deposited sediments had an obvious effect on aquatic macrophytes growth, and the impacts of light intensity, heavy metals, temperature and pH on the growth of aquatic macrophytes were little than that of the above factors. The problems existed in present researches were: dynamic and quantificational studies of the impacts of some stress factors on aquatic macrophytes growth were insufficient, there was lack of integrated investigations considering several factors which were of complex relationship.

Abstract: Cipangopaludina chinensis was exposed to Roxithromycin, and the first, the fifth and the tenth days of the C. chinensis were chosen, then the liver of the C. chinensis were made into slices. The results showed that the live treated by Roxithromycin had shown certain changes in the structure. The liver cells were disorganized, and the number of fat bubbles increased. What’s more, some nucleus deviated from the original position, and the number of ovarian follicles increased, too. This paper explored the effect of Roxithromycin in water on the morphology of tissues in C. chinensis in order to provide a reference about the environment of the growth of benthonic animals, and provide basis for the controlling and management of the water pollution as well as the bioremediations of water environment.

Abstract: Nitrification and denitrification plays an important role in the nitrogen cycle in wetlands. The nitrification and denitrification potentials of soil from different depths (0-40 cm) in Liaohe estuary wetland were studied with laboratorial batch incubation for three weeks. The results showed that the percent of nitrification and denitrification in soil at different depth were about 25-40% and 31-63% of soil total added nitrogen over three weeks, respectively. Both the denitrification and nitrification of soil at different depth showed an exponential decay trend over the incubation period. The corresponding rates were 0.013–0.021 mg·kg^-1·d^-1 and 0.017–0.057 mg·kg^-1·d^-1. The value of surface soil (0-5cm) was significant higher than that of the subsoil (5-40 cm) (p < 0.05) and there was no significant difference between values of the subsoil (p > 0.05).

Abstract: Degradation of paraoxon and thioanisole (PhSMe) were studied using NH₃ modified H₂O₂ solution as decontaminant. Degradation rates of paraoxon depend exponentially on pH of the modified solution. Nucleophilic substitution mediated by HOO^- is the major degradation mechanism and at least two orders of magnitude faster than hydrolysis. Proton catalytic oxidation and solvent-aided oxidation contribute differently to the primary oxidation of PhSMe (PhSMe→PhS(O)Me), and the apparent kinetic constants (k_ap) of the primary oxidation show a three-stage profile with pH of the NH₃-modified H₂O₂ solution. Secondary oxidation of PhSMe (PhS(O) Me→PhS(O)₂Me) is much slower than the primary oxidation in the modified H₂O₂ solution, and the yield of PhS(O)₂Me depended exponentially on pH too. The best pH range for the NH₃ modified H₂O₂ solution as a broad-spectrum decontaminant is at 9.5-10.0 since a balance of nucleophilic/oxidizing decontamination reactivity could be achieved.

Abstract: Understanding the chronological change in soil microbial community structure of tree peony garden ecosystem is important from ecological, environmental, and management perspectives. Soil samples were collected from three tree peony garden systems (5-, 12-, and 25-year-old tree peony gardens), and adjacent wasteland at Luoyang, Henan Province of China. Soil microbial community structure was analyzed by phospholipid fatty acid (PLFA) method. The bacterial and actinomycete PLFAs increased from the wasteland to 5-year-old tree peony garden and then decreased from the 5- to 25-year-old tree peony garden, and the fungal PLFA first increased and then decreased with the increasing planting years, with the greatest amount found in the 12-year-old tree peony garden. The conversion from the wasteland to tree peony garden resulted in a significant increase in Shannon index, Richness, and Evenness. However, with the succeeding development of tree peony garden ecosystems, Shannon index, Richness, and Evenness decreased from the 5- to 25-year-old tree peony garden.

Abstract: Based on the photoautotrophic characteristics of the freshwater microalage, light intensity attenuation characteristics in the cell culture system for Chlorella sp. were studied. Micralgae was cultured with a constant and the gradient light illuminate culture conditions, the cell growth of Microlagae was detected respectively, By means of regression analysis, mathematical models of illuminance intensity attenuation are gotten under different culture conditions. Results show algae cell density under gradient light culture conditions is higher than constant light, so the gradient light is more suitable for the cultivation of microalgae.

Abstract: In view of the pollution of heavy metals in tailings of mining area, considering some metal recycling, in this paper, the method which was environmental friendly, mild reaction, short process, low energy consumption was applied to leaching As and Cd in tailings. Before leaching, Static Magnetic Field was used to deal with leach liquor, to research the effect of leaching rate for As and Cd. The results showed that under the conditions of pulp density 5%, inoculum 10%, leaching temperature 30°C, pH 2.0, magnetic induction intensity separately were 2mT , 5mT , 8mT and 11mT, the leaching rates of As and Cd were increased respectively about 8% and 2%. Besides, magnetic induction intensity also effected. The best magnetic induction intensity in bioleaching of As and Cd were respectively 2mT and 8mT.

Abstract: The diversity of macroinvertebrate in Sha River and Xiangshui River of Dongjiang (China) were investigated in June 2013. According to the index of biological diversity and integrity, the water quality was evaluated. It provided a reference for water pollution controlling and water resources protection.