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Experimental investigation of lateral displacement of PVD-improved deposit
Chai, Jin-Chun,Xu, Fang Techno-Press 2015 Geomechanics & engineering Vol.9 No.5
Laboratory model tests were conducted to investigate the effect of surcharge loading rate on the magnitude of lateral displacement of prefabricated vertical drains (PVDs) improved deposit. The test results indicate that under the condition that the system had sufficient factor of safety (FS) ($FS{\geq}1.2$), for the similar model ground under the same total applied surcharge load, the lateral displacement increases with the increase of loading rate. The test results have been used to check the validity of a previously proposed method for predicting the maximum lateral displacement, and it shows that the data points are around the middle line of the predicted range, which supports the usefulness of the proposed method. The basic idea of the prediction method is an empirical relationship between the normalized lateral displacement (NLD) and a ration of load to the undrained shear strength of the deposit (RLS). The model test results offer some modifications of the NLD-RLS relationship: (1) instead of a bilinear relationship, NLD-RLS relationship may be entirely nonlinear; (2) the upper bound value of RLS for the proposed method can be used may be limited to 2.1 instead of the originally proposed value of 3.0.
Wang, Fang,Stedtfeld, Robert D.,Kim, Ok-Sun,Chai, Benli,Yang, Luxi,Stedtfeld, Tiffany M.,Hong, Soon Gyu,Kim, Dockyu,Lim, Hyoun Soo,Hashsham, Syed A.,Tiedje, James M.,Sul, Woo Jun American Chemical Society 2016 Environmental science & technology Vol.50 No.23
<P>Soil is an important environmental reservoir of antibiotic resistance genes (ARGs), which are increasingly recognized as environmental contaminants Methods to assess the risks associated with the acquisition or transfer of resistance mechanisms are still underdeveloped. Quantification of background levels of antibiotic resistance genes and what alters those is a first step in understanding our environmental resistome. Toward this goal, 62 samples were collected over 3 years from soils near the 30-year old Gondwana Research Station and for 4 years before and during development of the new Jang Bogo Research Station, both at Terra Nova Bay in Antarctica. These sites reflect limited and more extensive human impact, respectively. A qPCR array with 384 primer sets targeting antibiotic resistance genes and mobile genetic elements (MGEs) was used to detect and quantify these genes. A total of 73 ARGs and MGEs encompassing eight major antibiotic resistance gene categories were detected, but most at very low levels. Antarctic soil appeared to be a common reservoir for seven ARGs since they were present in most samples (42%-88%). If the seven widespread genes were removed, there was a correlation between the relative abundance of MGEs and ARGs, more typical of contaminated sites. There was a relationship between ARG content and distance from both research stations, with a significant effect at the Jang Bogo Station especially when excluding the seven widespread genes; however, the relative abundance of ARGs did not increase over the 4 year period. Silt, clay, total organic carbon, and SiO2 were the top edaphic factors that correlated with ARG abundance. Overall, this study identifies that human activity and certain soil characteristics correlate with antibiotic resistance genes in these oligotrophic Antarctic soils and provides a baseline of ARGs and MGEs for future comparisons.</P>
Arsenic Toxicity on Duck Spermatozoa and the Ameliorating Effect of L-Ascorbic Acid
Lin, Chai-Ching,Huang, Chia-Cherng,Chen, Ming-Cheng,Huang, Andrew Jeng-Fang,Chiou, Hung-Yi Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.1
The objectives of this study were to understand the possible mechanism of duck sperm toxicity induced by arsenic exposure in vivo, and to investigate the roles of the antioxidant L-ascorbic acid in ameliorating the arsenic-induced sperm impairment. To test the acute toxicity, the percentages of mortality of mature drakes treated with different concentrations of trivalent sodium arsenite, As (III), and pentavalent sodium arsenate, As (V) were measured. The LD50 value of As (III) for mature drakes was $4.89{\pm}1.49$ ppm. Although As (V) didn't cause any deaths even at a concentration of 40 ppm, the chronic toxicity of As (V) on sperm quality was shown by a decreased fertilization rate. When the concentrations of As (V) were above 0.4 ppm, fertilization rates were lower than those of 0.04 ppm and control. Drakes treated with 40 ppm of As (V) had the highest malondialdehyde (MDA) level in the testis tissue, $3.100{\pm}0.218{\mu}mole/g$ testis. This showed that 40 ppm of As (V) significantly induced lipid peroxidation in testis tissue. For the 1.2 ppm As (III) treatment, several significant effects were observed: (1) sperm motility was decreased most dramatically by $52.0{\pm}9.1$% after three days of incubation; (2) fertilization rate of artificially inseminated semen was the lowest, $26.4{\pm}15.4$; (3) the MDA concentration in testis tissue, $7.846{\pm}0.246{\mu}mole/g$ testis, was significantly higher than the others (p<0.05); (4) the sperm number, $1.17{\pm}0.40({\times}10^9)$, was significantly lower than with the 60 ppb and control treatments (p<0.05); (5) a black appearance and soft texture was observed in the testis tissue. The antioxidant L-ascorbic acid administered along with 1.2 ppm As (III) decreased the toxicity of arsenic. The ameliorating effects included: improved sperm motility, increased sperm number and fertilization rate, and decreased MDA concentration in the testis tissue. This study suggests that the toxicity of the trivalent arsenic on sperm quality is partly from free radicals generated by its metabolic pathway, and the antioxidant ascorbic acid ameliorates arsenic-caused sperm impairment.
A study of microstructures and mechanical properties of laser welded joint in GH3030 alloy
Tao Zhan,Fang Chai,Juan Zhao,Fei Yan,Wei Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6
In this paper, we represent experimental laser welding of GH3030 alloy. The microstructure and mechanical properties of laser welded joints were investigated using an optical microscope, scanning electron microscope, energy diffraction spectrum and other methodologies. The results demonstrated that the weld primarily involved slender dendrites together with a small number of equiaxial crystals. The occurrence of porosities was mainly associated with the composition of the material itself. The cracks in the HAZ were induced by lowmelting-point eutectic phases that formed during laser welding. The segregation of the alloying elements in the matrix induced the variation of the performance within the joint. The average strength of welded joints was 646 MPa, 97.6 % of that of the base metal. Formation of inclusions and micropores in the fusion zone weakened the joint strength greatly.
Fei Yan,Xiaozhong Du,Fang Chai,Chunming Wang,Kejia Zhuang,Juan Zhao,Wei Wang 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.6
In this study, we present the experimental laser welding of super-eutectic ZA alloy. Microstructures of the ZA alloy′s bond area welded by pulsed laser were investigated using an optical microscope, scanning electron microscope, energy diffraction spectrum and X-Ray diffractometer. The results showed that microstructures in the weld mainly consisted of threadlike columnar crystals, coarse dendrites and fine equiaxed grains. Secondary particles were produced in the interdendritic zones because of the composition segregation. A poor Al area was formed inside the η grain while a rich Al area takes shape outside the η grain. The occurrence of the composition segregation can increase the grain boundary cracking tendency. The existence of a large number of η phase greatly intensified the brittle of this material. The presence of many cleavage steps in the fractograph principally depended on the secondary cleavage effect between two cleavage cracks on different planes. The evolution of cracks along the twinning plane was the result of the secondary cleavage substituting for the twinning deformation in the vicinity of the crack tip.
Bayesian Network Model for XML Document Ranking
Jian Min Xu,Bian Fang Chai,Shuang Zhao 한국어정보학회 2006 한국어정보학 Vol.8 No.1
As more and more data is described, stored, exchanged and represented by XML, the abilities of information retrieval for XML document become increasingly important. However, the retrieval results to users are quite large. This paper gives a Bayesian network‐based model for ranking these large results. Each XML document is modeled through a Bayesian network, which can handle both structure and content for the document. And then this paper presents the inference for the probability of each document on the given query. Finally documents are ranked according to the probabilities in descent.