Applied Mechanics and Materials Vols. 448-453

Abstract: In order to evaluate the water quality of Longjiang river comprehensively, diatoms of 15 sampling sites are collected to establish the Grey Relational Model based on three diatom indexesIPS, IBD and IDG. From the Cluster analysis of sampling sites and the box plot of diatom index, IBD is the best, then the IPS, the diatom index weights on water quality assessment are 0.637 for IBD, 0.2583 for IPS, 0.1074 for IDG respectively. Finally, by comparing the water quality standard level based on Grey Relational Model, it can be known that the water quality of most sampling sites is fine except that site No.1 and No.3 belong to III water quality standard. The result shows that it is more comprehensive and reasonable to use the Grey Relational Model based on diatom index rather than individual diatom index to assess water quality.

Abstract: The aggregation kinetics of C60 nanoparticles have been investigated over a wide range of monovalent and divalent electrolyte concentrations by employing time-resolved dynamic light scattering (DLS). The results showed that the presence of electrolyte made a dramatic decrease in the surface zeta potential and increase in the particle size. The aggregation kinetics of C60 nanoparticles exhibited reaction-limited and diffusion-limited regimes, which was found to be consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. The critical coagulation concentration (CCC) values of C60 nanoparticles were estimated as 321mM Na⁺, 295mM K⁺, 9.6mM Ca²⁺ and 6.7mM Mg²⁺, which were far higher than the electrolyte concentrations in natural water. The enhanced C60 stability in the presence of humic acid was attributable to steric repulsion. Therefore C60 nanoparticles can be relatively stable in typical aquatic environments.

Abstract: Nutrient elements from litter decomposition was viewed as the main source of essential elements for normal growing of the forest tree. In this study, selected litter leaves of several typical desert plants as study materials, and deferent element contents of the litter leaves were analyzed. The main results are as belows: (1) There were significant differences in the levels of C, N, P, K, Ca, Mg and K between litter leaves of different desert plants (p < 0.01). (2) Significant differences were found in the nutrition re-utilization rate of the withered leaves of different plants, with P > K > N. Haloxylon ammodendron has the highest N utilization rate of 88.33%. Calligonum mongolicum has the lowest P utilization rate of 95.13%. Elaeagnus angustifolia has the highest K utilization rate of 77.49%.

Abstract: Free Trade Area (FTA) reached and validated between ASEAN and China has promoted plant and plant products trade dramatically between Thailand and China since 2000. As the agricultural products trade has kept increased rapidly, the pests management and quarantine become serious and challenging to these two countries in terms of ecological security and biosafety. This paper analyzed the situation of plant and plant products trade between Thailand and China from 2003 to 2012, including the kinds and amounts of plant and plant production, epidemic situation analysis which carried by import and export plant and plant products. There are over 400 kinds of plant and plant products which were trade between Thailand and China, and over 1000 genera (species) pests were intercepted including 79 genera (species) quarantine pests. In this paper, the bilateral arrangement related to plant quarantine was also analyzed. The current issues and problems of quarantine pests research, management and quarantine are articulated and suggestions how to improve or upgrade related researches and quarantine level were proposed in this paper.

Abstract: In this paper, the acute toxicity test was used to study the effects of different concentrations of suspended solids on the growth of zooplankton from Jiaozhou Bay. The experiment result showed that there had a significant impact of suspended solids on zooplankton growth and the mortality rate rose with the increasing concentration of suspended solids. The lethal concentration of 96h-LC50 was 60.172mg / L.

Abstract: The seedling was developed on the dark condition by artificial climate chamber to determine the content of Auxin (IAA), activity of indoleacetic acid oxidase (IAO) and cell wall peroxidase (POD), mesocotyl length change and cell wall oxidase activity variation applied IAA. The study proves that endogenous hormone IAA content of long mesocotyl in weedy rice were much higher than that of short mesocotyl in Akimitsu. With the growth of mesocotyl elongation, endogenous IAA content showed cumulative effects. And then accumulation of IAA content reached up to maximum, when the Mesocotyl elongation stoped to grow. IAA might play a decisive role in the process of hypocotyl elongation. Reduction in the activity of IAO and POD accelerated the transformation from bound IAA to free IAA and promoted cell elongation and mesocotyl elongation.

Abstract: A pot experiment was conducted to explore the physiological toxicity of mercury (Hg) and alleviatory effects of exogenous silicon (Si) on Pleioblastus fortunei by the determination of leaf membrane permeability, chlorophyll and soluble protein content, SOD and POD activity, root vigor, net photosynthetic rate. The results indicated that 20 mg/kg Hg²⁺ treatment for 100 days caused no obvious physiological effect on Pleioblastus fortunei except for root vigor. As the concentration of Hg²⁺ increased from 20 mg/kg to 500 mg/kg, the degree of physiological injury increased, and 500 mg/kg Hg²⁺ exhibited significant physiological toxicity to Pleioblastus fortunei. Application of 300 mg/kg Si had no apparent regulatory effect on physiological response of Sasa fortunei in the presence of 20 mg/kg Hg²⁺, but significantly alleviated the toxicity of 500 mg/kg Hg²⁺. Si could prohibite the descent of SOD activity and the increase of POD activity caused by high concentration of Hg²⁺, thus maintain the metabolism balance of active oxygen. Pleioblastus fortunei can be considered as phytoremediation plant and Si to improve resistance of bamboos cultivated in Hg polluted area.

Abstract: Before being put to use, a new condenser of 600 MW unit was found corrosion leakage of a large number of 304L stainless steel tubes during the water leakage test. Through field investigation, sampling, chemical composition and mechanical properties test, metallographic analysis, corrosion area surface morphology and micro area component analysis, corrosion reasons were analyzed. The main reason for corrosion is improper installation. Stainless steel tubes were polluted by rain, soil, welding slag during the installation process. Carbon steel members cut the tubes when wore tubes, and was placed in such condition for a too long time. Moreover, the electric current occurred in repair welding with water may accelerate pitting holes.

Abstract: A new environment-friendly automatic steel alloyed with tin element Y20Sn has been developed. In test, new steel possess good machinability and mechanical property, which reach Chinese National Standard of corresponding automatic steel GB/T8731-88. In steel, the shape of inclusions is mainly spherical or spindly, which volume is small and distribution is evenly. Such style of inclusion can fairly improve the steel machinability, and doesnt impair its mechanical property at the same time. As the main inclusion in developed automatic steel, MnS inclusion is one important factor which influences the machinability of steel. In the steel alloyed with tin, tin exist around MnS inclusions or are attached to MnS inclusion will influence the formation mechanism of MnS inclusion, that is the important reason why tin element influence machinability of developed automatic steel Y20Sn.

Abstract: A novel aurous complex containing thiourea and thiocyanate as the mixed ligands is synthesized by the ISRC method in this paper. Its formula is determined as [Au (tu)₂ ]SCN H₂O by elemental analysis. The electrochemistry studies show it is a typical ionic compound and its conductivity reaches 13×10^-4 Sm²mol^-1. TG studies and related stability tests reveal the compound is excellently stable. By using single factors experiments the optimal plating index has been gotten and they are: pH=1.5~3.5, [A =1.5~2.5 g/L, temperature 30~50°C and plating time 10 minutes respectively. It is a competitive gold complex and will be find a wide application in electroplating, chemical deposition, ceramic decoration and other related areas.