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S. Altai,S. L. Orton,F. M. Hussein,Z. Chen 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2
Prediction of possible structural collapse scenarios requires the experimental characterization of post-peak behaviors of structural members. The post-peak behavior of one member in a redundant structural system will influence the behaviors of the other members and ultimately the overall structural response. In this work, an experimental and numerical study was conducted to explore the failure behavior of structural systems consisting of three members arranged in parallel under tension. Twelve cylindrical A36 steel specimens with diameter (D) of 7.62 mm (0.3 in.) and length (L = 10D) of 76.2 mm (3 in.) were made for the experiments. Three specimens were used in single member tests to determine the base material properties. Three tests of three-member systems (Test-1, Test-2, and Test-3) were conducted using a special fixture that could rotate around a central pin in response to unbalanced forces produced due to unsymmetrical failure evolution in the three-member systems. A 3D DIC (three-dimensional Digital Image Correlation) measurement device was used to capture the deformations along the specimen length. The experimental results showed that all single members failed at approximately the same strength but with distinctly different displacement fields. In the three-member system tests, one system failed at 10% higher load, 21% lower displacement, and 13 times the rotation, as compared with the other two systems due to the softening of one outer member substantially before the other two members. The numerical results of the three-member system showed an acceptable correlation with the experiments. It could be concluded from this experimental study that the inconsistency of softening response, due to the inevitable imperfection of geometry, material and/or loading, can trigger the softening of one member before the others and significantly impact lateral displacement or rotation in a collapsing system.
L. Cheng,S.M. Zhang,P.P. Chen,S.L. Huang,L. Liu,W. Zhou,J. Liu,H. Gong,Q.M. Luo 한국물리학회 2007 Current Applied Physics Vol.7 No.s1
Poly(D,L-lactide) (PDLLA)/uorohydroxyapatite nanocrystals (nano-F-HA) porous scaolds were successfully fabricated through asolvent-casting and particulate-leaching technique. Nano-HA/PDLLA scaold and PDLLA scaold were prepared by using the sameprocess for comparison. The structure, phase and morphology of the nanocomposite scaolds were observed by SEM. The results indi-cated that F-HA nanocrystals were homogeneously dispersed in the PDLLA matrix. The porosity of the scaolds was up to 90%, andmacropores and micropores coexisted and interconnected throughout the scaolds. Cell culture experiments demonstrated that the nano-F-HA/PDLLA scaffold had the best adhesion tendency to chondrocytes among the scaffolds investigated.
Pan, S.Y.,Liu, H.L.,Chang, E.E.,Kim, H.,Chen, Y.H.,Chiang, P.C. Pergamon Press 2016 CHEMOSPHERE - Vol.154 No.-
Basic oxygen furnace slag (BOFS) exhibits highly alkaline properties due to its high calcium content, which is beneficial to carbonation reaction. In this study, accelerated carbonation of BOFS was evaluated under different reaction times, temperatures, and liquid-to-solid (L/S) ratios in a slurry reactor. CO<SUB>2</SUB> mass balance within the slurry reactor was carried out to validate the technical feasibility of fixing gaseous CO<SUB>2</SUB> into solid precipitates. After that, a multiple model approach, i.e., theoretical kinetics and empirical surface model, for carbonation reaction was presented to determine the maximal carbonation conversion of BOFS in a slurry reactor. On one hand, the reaction kinetics of BOFS carbonation was evaluated by the shrinking core model (SCM). Calcite (CaCO<SUB>3</SUB>) was identified as a reaction product through the scanning electronic microscopy and X-ray diffraction analyses, which provided the rationale of applying the SCM in this study. The rate-limiting step of carbonation was found to be ash-diffusion controlled, and the effective diffusivity for carbonation of BOFS in a slurry reactor were determined accordingly. On the other hand, the carbonation conversion of BOFS was predicted by the response surface methodology (RSM) via a nonlinear mathematical programming. According to the experimental data, the highest carbonation conversion of BOFS achieved was 57% under an L/S ratio of 20 mL g<SUP>-1</SUP>, a CO<SUB>2</SUB> flow rate of 0.1 L min<SUP>-1</SUP>, and a pressure of 101.3 kPa at 50 <SUP>o</SUP>C for 120 min. Furthermore, the applications and limitations of SCM and RSM were examined and exemplified by the carbonation of steelmaking slags.
The Expression of Genes Related to Egg Production in the Liver of Taiwan Country Chickens
Ding, S.T.,Ko, Y.H.,Ou, B.R.,Wang, P.H.,Chen, C.L.,Huang, M.C.,Lee, Y.P.,Lin, E.C.,Chen, C.F.,Lin, H.W.,Cheng, Winston Teng Kuei Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.1
The purpose of this study was to detect expression of genes related to egg production in Taiwan Country chickens by suppression subtractive hybridization. Liver samples of mRNA extraction from two Taiwan Country chicken strains (L2 and B), originated from the same population but with very distinct egg production rates after long-term selection for egg and meat production respectively. Two-way subtraction was performed. The hepatic cDNA from the low egg production chickens (B) was subtracted from the hepatic cDNA from the high egg production strain (L2). The reversed subtraction (L2 from B) was also performed. The resulting differentially expressed gene fragments were cloned and sequenced. We sequenced 288 clones from the forward subtraction and 96 clones from the reverse subtraction. These genes were subjected to further screening to confirm the differential expression between the two genetic breeds of chickens. The apolipoprotein B (apoB) was expressed to a greater extent in the liver of the L2 than in the B line chickens. The 5-aminoimidazole- 4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (PURH) was expressed to a greater extent in the liver of the B than in the L2 strain chickens. We demonstrated that both apoB and PURH were more highly expressed in the liver than that in other tissues (muscle, ovary, and oviduct) in laying Taiwan Country chickens. Taken together, these data suggest that after the selection for egg production, expression of apoB and PURH genes were also changed. Whether the changed expression of these genes is directly related to egg production is not known, but these two genes may be useful markers for egg laying performance in Taiwan Country chickens.
Kafle, G.K.,Bhattarai, S.,Kim, S.H.,Chen, L. Academic Press 2014 Journal of environmental management Vol.133 No.-
The objective of this study was to investigate the effect of the feed-to-microbe (F/M) ratios on anaerobic digestion of Chinese cabbage waste (CCW) generated from a kimchi factory. The batch test was conducted for 96 days under mesophilic (36.5 <SUP>o</SUP>C) (Experiment I) and thermophilic (55 <SUP>o</SUP>C) conditions (Experiment II) at F/M ratios of 0.5, 1.0 and 2.0. The first-order kinetic model was evaluated for methane yield. The biogas yield in terms of volatile solids (VS) added increased from 591 to 677 mL/g VS under mesophilic conditions and 434 to 639 mL/g VS under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. Similarly, the volumetric biogas production increased from 1.479 to 6.771 L/L under mesophilic conditions and from 1.086 to 6.384 L/L under thermophilic conditions when F/M ratio increased from 0.5 to 2.0. The VS removal increased from 59.4 to 75.6% under mesophilic conditions and from 63.5 to 78.3% under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. The first-order kinetic constant (k, 1/day) decreased under the mesophilic temperature conditions and increased under thermophilic conditions when the F/M ratio increased from 0.5 to 2.0. The difference between the experimental and predicted methane yield was in the range of 3.4-14.5% under mesophilic conditions and in the range of 1.1-3.0% under thermophilic conditions. The predicted methane yield derived from the first-order kinetic model was in good agreement with the experimental results.
Shear Thickening Polishing of Black Lithium Tantalite Substrate
B. H. Lyu,Q. Shao,W. Hang,S. H. Chen,Q. K. He,J. L. Yuan 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9
To achieve high efficiency in the polishing process to obtain a high surface quality of black LT substrate (a kind of soft brittle material), shear thickening polishing (STP), which is a “gentle” finishing process developed in recent years, was employed in this study. The influence of three key parameters in the STP process including polishing speed, diamond abrasive size and diamond abrasive concentration were analyzed. To investigate the potential mechanical effect of the nanometre abrasive, nano-SiO 2 abrasive particles were added in the slurry, and the concentration of SiO 2 abrasive was also taken as a factor. Taguchi method was utilized to evaluate the influence of the four factors and optimize the polishing conditions. The surface roughness (Ra/Rz) was used as the evaluation index, and the optimized polishing conditions were verified through experiments. Diamond abrasive size has the most significant effect on Ra/Rz, followed by diamond abrasive concentration and then SiO 2 concentration, as the polishing speed has been selected and limited in a small variation rang according to the previous study. Based on the S/N average response analysis, the surface quality is the best under the conditions with 8000# diamond abrasive, 5 wt% diamond abrasive concentration, 90 rpm polishing speed and 10 wt% SiO 2 concentration. After 4 min polishing, the surface roughness Ra/Rz is reduced rapidly from 200.5/1374.6 to 4.2/22.1 nm without embedded abrasive particles on the surface of the black LT substrate. It also shows that the mechanical effect plays a dominant role in the material removal. A certain amount (10 wt% in this study) of nano-SiO 2 can reduce friction between solid colloidal and workpiece, and helps to improve surface quality.