Chronic pancreatitis(CP)is a progressive inflammatory disease of pancreas that alters the organ’s normal structure and functions.CP seriously affects the quality of life of patients and greatly increases the public m...Chronic pancreatitis(CP)is a progressive inflammatory disease of pancreas that alters the organ’s normal structure and functions.CP seriously affects the quality of life of patients and greatly increases the public medical burden of society.In recent years,the incidence of CP has increased worldwide.The concepts of etiology and therapies have been continuously updated.展开更多
To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed...To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed using the commercial software MSC.MARC, and microstructures and fractographs were also observed. With the finite element models, the contours of temperature, equivalent plastic strain, and equivalent vun Mises stress were simulated. It is observed that the fracture surfaces of internal cracks are covered by cleavage or quasi-cleavage facets. The region of internal cracks in the intergranular brittle fracture mode is in the mushy zone between the zero ductility temperature （ZDT） and the zero strength temperature （ZST）. The simulated equivalent plastic strain in the crack region is 2.34%-2.45%, which is larger than the critical strain （0.4%-1.5%）, and the equivalent von Mises stress is 1.84-5.05 MPa, which is within the range of criti- cal stress （3.9-7.2 MPa）, thus resulting in the occurrence of internal cracks. Reducing the soft reduction amount from 3 to 2 mm can lower the stress under the critical value.展开更多
The precipitation of spherical boehmite was studied by surface energy calculations, measurements of precipitation ratios, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and t...The precipitation of spherical boehmite was studied by surface energy calculations, measurements of precipitation ratios, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The surface energy calculation results show that the(001) and(112) planes of gibbsite surfaces are remarkably stable because of their low surface energies. In addition, the(010) plane of boehmite grows preferentially during precipitation because of its low surface energy. Thus, we propose a method to precipitate spherical boehmite from a supersaturated sodium aluminate solution by adding gibbsite as seed in a heterogeneous system. In this method, gibbsite acts as the preliminary seed and saturation modifier. The results show that the fine boehmite first nucleates on the(001) and(112) planes of gibbsite and then grows vertically on the(001) and(112) basal planes of gibbsite via self-assembly, thereby forming spherical boehmite. Simultaneously, gibbsite is dissolved into the aluminate solution to maintain the saturation for the precipitation of boehmite. The precipitation ratio fluctuates(forming an M-shaped curve) because of gibbsite dissolution and boehmite precipitation. The mechanism of boehmite precipitation was further discussed on the basis of the differences in surface energy and solubility between gibbsite and boehmite. This study provides an environmentally friendly and economical method to prepare specific boehmite in a heterogeneous system.展开更多
The recent increasing use of γ-rays industrial computed tomography(γ-rays ICT) in various fields has induced greater attention to its performance as well as to considerations of radiation safety. It is understood th...The recent increasing use of γ-rays industrial computed tomography(γ-rays ICT) in various fields has induced greater attention to its performance as well as to considerations of radiation safety. It is understood that radiation protection planning cannot be sacrificed for the sake of CT image quality during the design, manufacture,and layout of γ-rays ICT systems. In the present work, we describe a typical γ-rays ICT system in brief, and, based on experience and pertinent examples, we propose design requirements for ensuring the radiation safety of the sealed radioactive source, source container, and workspace. The design examples and dose rate measurement results illustrate that the proposed design standards are reasonable,feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-rays ICT systems. This paper discussed the predominant measures associated with the radiation protection of γ-rays ICT systems in accordance with the pertinent Chinese standards. In addition, based on experience and pertinent examples, the design requirements for ensuring the radiation safety of a sealed radioactive source, source container, and workspace were defined in detail. The design examples and dose rate measurements conducted in conjunction with a γ-rays ICT system and workspace employing the proposed design standards have illustrated that the proposals provided in this paper are reasonable, feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-rays ICT systems.展开更多
The surface properties of superfine alumina trihydrate （ATH） after surface modification were studied by measuring the contact angle, active ratio, oil adsorption, total organic carbon, adsorption ratio, and Fourier ...The surface properties of superfine alumina trihydrate （ATH） after surface modification were studied by measuring the contact angle, active ratio, oil adsorption, total organic carbon, adsorption ratio, and Fourier transform infrared （FTIR） spectrum. The contact angle increased initially and then slowly decreased with an increase of the amount of stearic acid. However, the surface flee energy decreased ini- tially and then increased. Surface modification with stearic acid or sodium stearate can benefit from elevating temperature. The base surface tension component and the free energy of Lewis acid-base both declined sharply following the surface modification. Excess stearic acid was physically adsorbed in the form of multilayer adsorption, and an interaction between oxygen on the ATH surface and hydroxyl in stearic acid was subsequently determined. Our results further indicated that the contact angle and adsorption ratio can be used as control indicators for surface modification compared with active ratio, oil adsorption and total organic carbon.展开更多
文摘Chronic pancreatitis(CP)is a progressive inflammatory disease of pancreas that alters the organ’s normal structure and functions.CP seriously affects the quality of life of patients and greatly increases the public medical burden of society.In recent years,the incidence of CP has increased worldwide.The concepts of etiology and therapies have been continuously updated.
基金Project(51604309)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare IndustryProject(2015CX001)supported by the Innovation-driven Plan in Central South University,China
基金Project(2019M652799)supported by China Postdoctoral Science FoundationProject(51604309)supported by the National Natural Science Foundation of China。
基金Project(51374239)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by Environmental Protection’s Special Scientific Research for Chinese Public Welfare IndustryProject(2015CX001)supported by the Innovation-driven Plan in Central South University,China
基金Project(51274243)supported by the National Natural Science Foundation of ChinaProject(2015CX001)supported by the Innovation-driven Plan in Central South University,China
基金financially supported by the Key Science and Technology Program of Liaoning Province, China (No.2007414003)
文摘To investigate the formation of internal cracks in GCrl 5 bearing steels during the soft reduction process in rectangular bloom con- tinuous casting, fully coupled thermomechanieal finite element models were developed using the commercial software MSC.MARC, and microstructures and fractographs were also observed. With the finite element models, the contours of temperature, equivalent plastic strain, and equivalent vun Mises stress were simulated. It is observed that the fracture surfaces of internal cracks are covered by cleavage or quasi-cleavage facets. The region of internal cracks in the intergranular brittle fracture mode is in the mushy zone between the zero ductility temperature （ZDT） and the zero strength temperature （ZST）. The simulated equivalent plastic strain in the crack region is 2.34%-2.45%, which is larger than the critical strain （0.4%-1.5%）, and the equivalent von Mises stress is 1.84-5.05 MPa, which is within the range of criti- cal stress （3.9-7.2 MPa）, thus resulting in the occurrence of internal cracks. Reducing the soft reduction amount from 3 to 2 mm can lower the stress under the critical value.
基金financially supported by the National Natural Science Foundation of China (No.51274242)the Fundamental Research Funds for the Central Universities of Central South University (No.2016zzts038)
文摘The precipitation of spherical boehmite was studied by surface energy calculations, measurements of precipitation ratios, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The surface energy calculation results show that the(001) and(112) planes of gibbsite surfaces are remarkably stable because of their low surface energies. In addition, the(010) plane of boehmite grows preferentially during precipitation because of its low surface energy. Thus, we propose a method to precipitate spherical boehmite from a supersaturated sodium aluminate solution by adding gibbsite as seed in a heterogeneous system. In this method, gibbsite acts as the preliminary seed and saturation modifier. The results show that the fine boehmite first nucleates on the(001) and(112) planes of gibbsite and then grows vertically on the(001) and(112) basal planes of gibbsite via self-assembly, thereby forming spherical boehmite. Simultaneously, gibbsite is dissolved into the aluminate solution to maintain the saturation for the precipitation of boehmite. The precipitation ratio fluctuates(forming an M-shaped curve) because of gibbsite dissolution and boehmite precipitation. The mechanism of boehmite precipitation was further discussed on the basis of the differences in surface energy and solubility between gibbsite and boehmite. This study provides an environmentally friendly and economical method to prepare specific boehmite in a heterogeneous system.
文摘The recent increasing use of γ-rays industrial computed tomography(γ-rays ICT) in various fields has induced greater attention to its performance as well as to considerations of radiation safety. It is understood that radiation protection planning cannot be sacrificed for the sake of CT image quality during the design, manufacture,and layout of γ-rays ICT systems. In the present work, we describe a typical γ-rays ICT system in brief, and, based on experience and pertinent examples, we propose design requirements for ensuring the radiation safety of the sealed radioactive source, source container, and workspace. The design examples and dose rate measurement results illustrate that the proposed design standards are reasonable,feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-rays ICT systems. This paper discussed the predominant measures associated with the radiation protection of γ-rays ICT systems in accordance with the pertinent Chinese standards. In addition, based on experience and pertinent examples, the design requirements for ensuring the radiation safety of a sealed radioactive source, source container, and workspace were defined in detail. The design examples and dose rate measurements conducted in conjunction with a γ-rays ICT system and workspace employing the proposed design standards have illustrated that the proposals provided in this paper are reasonable, feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-rays ICT systems.
基金financially supported by the National Natural Science Foundation of China (No. 51274242)
文摘The surface properties of superfine alumina trihydrate （ATH） after surface modification were studied by measuring the contact angle, active ratio, oil adsorption, total organic carbon, adsorption ratio, and Fourier transform infrared （FTIR） spectrum. The contact angle increased initially and then slowly decreased with an increase of the amount of stearic acid. However, the surface flee energy decreased ini- tially and then increased. Surface modification with stearic acid or sodium stearate can benefit from elevating temperature. The base surface tension component and the free energy of Lewis acid-base both declined sharply following the surface modification. Excess stearic acid was physically adsorbed in the form of multilayer adsorption, and an interaction between oxygen on the ATH surface and hydroxyl in stearic acid was subsequently determined. Our results further indicated that the contact angle and adsorption ratio can be used as control indicators for surface modification compared with active ratio, oil adsorption and total organic carbon.
基金Project(2015BAB04B01)supported by the National Key Technology Research&Development Program of ChinaProject(CSUZC201811)supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
基金Project(51274243)supported by the National Natural Science Foundation of ChinaProject(2015CX001)supported by the Innovation-driven Plan of Central South University,China
