This work aims to evaluate the feasibility of the fabrication of nanostructured Cu/Al/Ag multi-layered composites by accumulative roll bonding(ARB),and to analyze the tensile properties and electrical conductivity of ...This work aims to evaluate the feasibility of the fabrication of nanostructured Cu/Al/Ag multi-layered composites by accumulative roll bonding(ARB),and to analyze the tensile properties and electrical conductivity of the produced composites.A theoretical model using strengthening mechanisms and some structural parameters extracted from X-ray diffraction is also developed to predict the tensile strength of the composites.It was found that by progression of ARB,the experimental and calculated tensile strengths are enhanced,reach a maximum of about 450 and 510 MPa at the fifth cycle of ARB,respectively and then are reduced.The electrical conductivity decreased slightly by increasing the number of ARB cycles at initial ARB cycles,but the decrease was intensified at the final ARB cycles.In conclusion,the merit of ARB to fabricate this type of multi-layered nanocomposites and the accuracy of the developed model to predict tensile strength were realized.展开更多
AIM:To investigate the diagnosis of nonalcoholic steatohepatitis(NASH) using contrast ultrasonography in the NASH rat model.METHODS:The liver in methionine choline-deficient diet(MCDD) rats,a NASH model constructed by...AIM:To investigate the diagnosis of nonalcoholic steatohepatitis(NASH) using contrast ultrasonography in the NASH rat model.METHODS:The liver in methionine choline-deficient diet(MCDD) rats,a NASH model constructed by feeding an MCDD,was examined by contrast ultrasonography at weeks 2,4,8,12 and 16,with late phase images of contrast ultrasonography(Kupffer imaging) in which contrast enhancement was achieved by incorporation of a contrast agent by Kupffer cells(KCs),and images were compared to those in rats taking a regular chow.RESULTS:Decrease in contrast enhancement was observed first in MCDD rats at week 2.KCs were counted based on immunohistochemistry,but their numbers were not reduced and it was assumed that attenuation of contrast enhancement was attributable to reduced phagocytic activity of the KCs.CONCLUSION:It is suggested that clinical application of contrast ultrasonography may be valuable for noninvasive diagnosis of NASH.展开更多
Rockburst occurred frequently during deep mining in China. The mechanism of rockburst is very complicated and related to many factors. In order to investigate the influence of moisture contents of rockmass on rockburs...Rockburst occurred frequently during deep mining in China. The mechanism of rockburst is very complicated and related to many factors. In order to investigate the influence of moisture contents of rockmass on rockburst, we conducted a series of laboratory rockburst experiments of sandstone under three different moisture contents by the Modified True-Triaxial Apparatus (MTTA),in which the acoustic emission (AE) system was employed to monitor the internal damage of rock mass. A high-speed video camera was utilized to record the detail of rockburst. Based on the experimental results, the AE characteristics, such as AE count,AE energy, and AE frequency, were analyzed. The rockburst process, type, and indensity under different moisture contents were discussed. The research results show that with the increase of moisture contents, rock strength was soften, the elastic and the cumulative damage of the rock were reduced, resulting in a gradual decrease in AE cumulative counts and cumulative energy over the course of rockburst. This study provides an experimental basis and reference for better understanding to the rockburst mechanism and control.展开更多
文摘This work aims to evaluate the feasibility of the fabrication of nanostructured Cu/Al/Ag multi-layered composites by accumulative roll bonding(ARB),and to analyze the tensile properties and electrical conductivity of the produced composites.A theoretical model using strengthening mechanisms and some structural parameters extracted from X-ray diffraction is also developed to predict the tensile strength of the composites.It was found that by progression of ARB,the experimental and calculated tensile strengths are enhanced,reach a maximum of about 450 and 510 MPa at the fifth cycle of ARB,respectively and then are reduced.The electrical conductivity decreased slightly by increasing the number of ARB cycles at initial ARB cycles,but the decrease was intensified at the final ARB cycles.In conclusion,the merit of ARB to fabricate this type of multi-layered nanocomposites and the accuracy of the developed model to predict tensile strength were realized.
文摘AIM:To investigate the diagnosis of nonalcoholic steatohepatitis(NASH) using contrast ultrasonography in the NASH rat model.METHODS:The liver in methionine choline-deficient diet(MCDD) rats,a NASH model constructed by feeding an MCDD,was examined by contrast ultrasonography at weeks 2,4,8,12 and 16,with late phase images of contrast ultrasonography(Kupffer imaging) in which contrast enhancement was achieved by incorporation of a contrast agent by Kupffer cells(KCs),and images were compared to those in rats taking a regular chow.RESULTS:Decrease in contrast enhancement was observed first in MCDD rats at week 2.KCs were counted based on immunohistochemistry,but their numbers were not reduced and it was assumed that attenuation of contrast enhancement was attributable to reduced phagocytic activity of the KCs.CONCLUSION:It is suggested that clinical application of contrast ultrasonography may be valuable for noninvasive diagnosis of NASH.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51374214 , 51134005 & 51574248)the Special Fund of Basic Research and Operating of China University of Mining & Technology, Beijing (Grant No. 2009QL03)the State Scholarship Fund of China
文摘Rockburst occurred frequently during deep mining in China. The mechanism of rockburst is very complicated and related to many factors. In order to investigate the influence of moisture contents of rockmass on rockburst, we conducted a series of laboratory rockburst experiments of sandstone under three different moisture contents by the Modified True-Triaxial Apparatus (MTTA),in which the acoustic emission (AE) system was employed to monitor the internal damage of rock mass. A high-speed video camera was utilized to record the detail of rockburst. Based on the experimental results, the AE characteristics, such as AE count,AE energy, and AE frequency, were analyzed. The rockburst process, type, and indensity under different moisture contents were discussed. The research results show that with the increase of moisture contents, rock strength was soften, the elastic and the cumulative damage of the rock were reduced, resulting in a gradual decrease in AE cumulative counts and cumulative energy over the course of rockburst. This study provides an experimental basis and reference for better understanding to the rockburst mechanism and control.
