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Hui Xu,Yichun Zhang,Bin Rong 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3
In this study, a combination of experiments and fi nite element analyses was conducted to investigate the eff ect of initial imperfections on the axial compression of the 7A04-T6 aluminum alloy columns. Prior to the loading tests, measurement of the initial geometric imperfections for the columns were performed by optical theodolite and vernier calipert. The failure modes of 10 extruded circular columns were investigated. Meanwhile, the ultimate strengths, defl ections and surface strains in whole process under axial compression were recorded. The fi nite element (FE) models of the tested columns were developed using the non-linear fi nite element analysis (FEA) software ABAQUS, and the imperfections and material nonlinearities were considered in the FE models. The validation of the FE models was performed against the test results; it was observed that the proposed FE models are suffi ciently accurate to predict the ultimate strengths and buckling behaviors of the tested columns.
Hui Li,Hong Xu,Sha Li,Hao Xu,Chaojiang Guo,Pingkai Ouyang,Hanjie Ying 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.5
Low-energy nitrogen ion beam implantation technique was used for the strain improvement of Alcaligenes sp. NX-3 for the production of exopolysaccharide welan gum. A high welan gum producing mutant, Alcaligenes sp. NX-3-1, was obtained through 20 keV N+ ion beam irradiation. Starting at a concentration of 50 g/L of glucose, mutant NX-3-1 produced 25.0 g/L of welan gum after 66 h of cultivation in a 7.5 L bioreactor, which was 34.4% higher than that produced by the wild-type strain. The results of metabolic flux analysis showed that the glucose-6-phosphate and acetyl coenzyme A nodes were the principle and flexible nodes, respectively. At the glucose-6-phosphate node, the fraction of carbon measured from glucose-6-phosphate to glucose-1-phosphate was enhanced after mutagenesis, which indicated that more flux was used to synthesize welan gum in the mutant. By analyzing the activities of related enzymes in the biosynthetic pathway of sugar nucleotides essential for welan gum production, we found that the specific activities of phosphoglucomutase, UDP-glucose pyrophosphorylase,UDP-glucose dehydrogenase, and dTDP-glucose pyrophosphorylase in the mutant strain were higher than those in the wild-type strain. These improvements in enzyme activities could be due to the affected of ion beam implantation.
Hui-Ru Xu,Ping-Yuan Lee,Ya-Wei Tsai,Ying-Chieh Lee 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.2
Titanium dioxide thin films with silver dopant (Ag-TiO2) were successfully prepared on glass substrates using the thermaloxidation method. Ag-doped titanium films were prepared using direct current (DC) and radio frequency (RF) magnetron cosputteringsystems. The thermal oxidation temperature and Ag content effects on the phase evolution, microstructure, andphoto catalytic activity of TiO2 film were studied. The crystalline structures and photo catalytic activity of the annealed AgdopedTiO2 films were methodically investigated using transmission electron microscopy (TEM), field emission scanningelectron microscopy (FESEM), X-ray diffraction (XRD), and ultraviolet spectrophotometry. The results exhibited that thethermal oxidation process at 550 oC clearly caused rutile phase formation in the 2.7% Ag-doped TiO2 films directly affectingthe photo catalytic activity. The Ag-doped TiO2 films showed good photo catalytic activity under UV-light radiation, with 59%methylene blue dye degradation rate.