Ni-Fe alloy was electrodeposited on the surface of polyacrylonitrile （PAN）-based carbon fibers, and catalytic graphitization effect of the heat-treated carbon fibers was investigated by X-ray diffractometry and Rama...Ni-Fe alloy was electrodeposited on the surface of polyacrylonitrile （PAN）-based carbon fibers, and catalytic graphitization effect of the heat-treated carbon fibers was investigated by X-ray diffractometry and Raman spectra. It is found that Ni-Fe alloy exhibits significant catalytic effect on the graphitization of the carbon fibers at low temperatures. The degree of graphitization of the carbon fibers coated with Ni-Fe alloy （57.91% Fe, mass fraction） reaches 69.0% through heat treatment at 1 250 °C. However, the degree of graphitization of the carbon fibers without Ni-Fe alloy is only 30.1% after being heat-treated at 2 800 °C. The catalytic effect of Ni-Fe alloy on graphitization of carbon fibers is better than that of Ni or Fe at the same temperature, indicating that Ni and Fe elements have synergic catalytic function. Furthermore, Fe content in the Ni-Fe alloy also influences catalytic effect. The catalytic graphitization of Ni-Fe alloy follows the dissolution-precipitation mechanism.展开更多
Viscose activated carbon fibers （ACFs） were characterized using specific surface area, scanning electron modified with chemical vapor deposition （CVD）. The samples were microscopy （SEM）, pore size distribution a...Viscose activated carbon fibers （ACFs） were characterized using specific surface area, scanning electron modified with chemical vapor deposition （CVD）. The samples were microscopy （SEM）, pore size distribution and Fourier transform infrared spectroscopy （FTIR）. Batch adsorption experiments were carried out to investigate the adsorption behavior of modified ACFs for methyl orange（MO） from its aqueous solutions. The results show that the adsorption isotherms of MO onto modified ACFs well follows the Langmuir isotherm equation. The adsorption kinetics of MO can be well described by the pseudo second-order kinetic model. The adsorption process involves the intra-particle diffusion, but is not the only rate-controlling step. Thermodynamic parameters including AG, AH and AS were calculated, suggesting that the adsorption of MO onto modified ACFs is a spontaneous, exothermic and physisorption process. FTIR result indicates that the major adsorption mechanism of modified ACFs for MO is hydrogen bond.展开更多
AIM： To study the liver and spleen volume variations in hepatic fibrosis patients at different histopathological stages. METHODS： Multidetector computed tomography （MDCT） scan was performed in 85 hepatic fibrosis ...AIM： To study the liver and spleen volume variations in hepatic fibrosis patients at different histopathological stages. METHODS： Multidetector computed tomography （MDCT） scan was performed in 85 hepatic fibrosis patients. Liver volume （LV） and spleen volume （SV） were measured. Fifteen healthy individuals served as a control group （SO）. The patients were divided into stage 1 （S1） group （n = 34）, stage 2 （S2） group （n = 25）, stage 3 （S3） group （n = 16）, and stage 4 （S4） group （n = 10） according to their histopathological stage of liver fibrosis. RESULTS： The LV and standard LV （SLV） had a tendency to increase with the severity of fibrosis, but no statistical difference was observed in the 5 groups （LV： F = 0.245, P = 0.912; SLV： F = 1.902, P = 0.116）. The SV was gradually increased with the severity of fibrosis, and a statistically significant difference in SV was observed among the 5 groups （P 〈 0.01）. The LV/SV ratio and SLV/SV ratio were gradually decreased with the aggravation of hepatic fibrosis, and statistically significant differences in both LV/SV and SLV/SV were found among the 5 groups （P 〈 0.01）.CONCLUSION： The absence of obvious LV reduction in patients with chronic liver disease may be a morphological index of patients without liver cirrhosis. The SV is related to the severity of fibrosis, and the spleen of patients with advanced fibrosis is enlarged evidently. The LV/SV ratio and SLV/SV ratio are of a significant clinical value in the diagnosis of advanced liver fibrosis.展开更多
An experimental study on the compressive behavior of steel fiber reinforced concrete-filled steel tube columns is presented. Specimens were tested to investigate the effects of the concrete strength, the thickness of ...An experimental study on the compressive behavior of steel fiber reinforced concrete-filled steel tube columns is presented. Specimens were tested to investigate the effects of the concrete strength, the thickness of steel tube and the steel fiber volume fraction on the ultimate strength and the ductility. The experimental results indicate that the addition of steel fibers in concrete can significantly improve the ductility and the energy dissipation capacity of the concrete-filled steel tube columns and delay the local buckling of the steel tube, but has no obvious effect on the failure mode. It has also been found that the addition of steel fibers is a more effective method than using thicker steel tube in enhancing the ductility, and more advantageous in the case of higher strength concrete. An analytical model to estimate the load capacity is proposed for steel tube columns filled with both plain concrete and steel fiber reinforced concrete. The predicted results are in good agreement with the experimental ones obtained in this work and literatures.展开更多
基金Project (2006CB600903) supported by the National Basic Research Program of ChinaProject (2010GK3208) supported by Science and Technology Program of Hunan Province, China
文摘Ni-Fe alloy was electrodeposited on the surface of polyacrylonitrile （PAN）-based carbon fibers, and catalytic graphitization effect of the heat-treated carbon fibers was investigated by X-ray diffractometry and Raman spectra. It is found that Ni-Fe alloy exhibits significant catalytic effect on the graphitization of the carbon fibers at low temperatures. The degree of graphitization of the carbon fibers coated with Ni-Fe alloy （57.91% Fe, mass fraction） reaches 69.0% through heat treatment at 1 250 °C. However, the degree of graphitization of the carbon fibers without Ni-Fe alloy is only 30.1% after being heat-treated at 2 800 °C. The catalytic effect of Ni-Fe alloy on graphitization of carbon fibers is better than that of Ni or Fe at the same temperature, indicating that Ni and Fe elements have synergic catalytic function. Furthermore, Fe content in the Ni-Fe alloy also influences catalytic effect. The catalytic graphitization of Ni-Fe alloy follows the dissolution-precipitation mechanism.
基金Project (50802115) supported by the National Natural Science Foundation of ChinaProject (2010FJ4075) supported by Science and Technology Planning Project of Hunan Province, China+1 种基金Project (CDJJ-10010205) supported by the Science Foundation of Changsha University, ChinaProject supported by the Construct Program of the Key Discipline in Hunan Province, China
文摘Viscose activated carbon fibers （ACFs） were characterized using specific surface area, scanning electron modified with chemical vapor deposition （CVD）. The samples were microscopy （SEM）, pore size distribution and Fourier transform infrared spectroscopy （FTIR）. Batch adsorption experiments were carried out to investigate the adsorption behavior of modified ACFs for methyl orange（MO） from its aqueous solutions. The results show that the adsorption isotherms of MO onto modified ACFs well follows the Langmuir isotherm equation. The adsorption kinetics of MO can be well described by the pseudo second-order kinetic model. The adsorption process involves the intra-particle diffusion, but is not the only rate-controlling step. Thermodynamic parameters including AG, AH and AS were calculated, suggesting that the adsorption of MO onto modified ACFs is a spontaneous, exothermic and physisorption process. FTIR result indicates that the major adsorption mechanism of modified ACFs for MO is hydrogen bond.
基金Supported by Science and Technology Program of Beijing Education Committee,No.KM200810025002
文摘AIM： To study the liver and spleen volume variations in hepatic fibrosis patients at different histopathological stages. METHODS： Multidetector computed tomography （MDCT） scan was performed in 85 hepatic fibrosis patients. Liver volume （LV） and spleen volume （SV） were measured. Fifteen healthy individuals served as a control group （SO）. The patients were divided into stage 1 （S1） group （n = 34）, stage 2 （S2） group （n = 25）, stage 3 （S3） group （n = 16）, and stage 4 （S4） group （n = 10） according to their histopathological stage of liver fibrosis. RESULTS： The LV and standard LV （SLV） had a tendency to increase with the severity of fibrosis, but no statistical difference was observed in the 5 groups （LV： F = 0.245, P = 0.912; SLV： F = 1.902, P = 0.116）. The SV was gradually increased with the severity of fibrosis, and a statistically significant difference in SV was observed among the 5 groups （P 〈 0.01）. The LV/SV ratio and SLV/SV ratio were gradually decreased with the aggravation of hepatic fibrosis, and statistically significant differences in both LV/SV and SLV/SV were found among the 5 groups （P 〈 0.01）.CONCLUSION： The absence of obvious LV reduction in patients with chronic liver disease may be a morphological index of patients without liver cirrhosis. The SV is related to the severity of fibrosis, and the spleen of patients with advanced fibrosis is enlarged evidently. The LV/SV ratio and SLV/SV ratio are of a significant clinical value in the diagnosis of advanced liver fibrosis.
基金Project(51078294)supported by the National Natural Science Foundation of ChinaProject(201101411100025)supported by the Doctoral Fund of Ministry of Education of China
文摘An experimental study on the compressive behavior of steel fiber reinforced concrete-filled steel tube columns is presented. Specimens were tested to investigate the effects of the concrete strength, the thickness of steel tube and the steel fiber volume fraction on the ultimate strength and the ductility. The experimental results indicate that the addition of steel fibers in concrete can significantly improve the ductility and the energy dissipation capacity of the concrete-filled steel tube columns and delay the local buckling of the steel tube, but has no obvious effect on the failure mode. It has also been found that the addition of steel fibers is a more effective method than using thicker steel tube in enhancing the ductility, and more advantageous in the case of higher strength concrete. An analytical model to estimate the load capacity is proposed for steel tube columns filled with both plain concrete and steel fiber reinforced concrete. The predicted results are in good agreement with the experimental ones obtained in this work and literatures.
