The problem considered is a mode Ⅲ crack lying parallel to the interface of an exponential-type functional graded material （FGM） strip bonded to a linear-type FGM substrate with infinite thickness. By applying the ...The problem considered is a mode Ⅲ crack lying parallel to the interface of an exponential-type functional graded material （FGM） strip bonded to a linear-type FGM substrate with infinite thickness. By applying the Fourier integral transform, the problem was reduced as a Cauchy singular integral equation with an unknown dislocation density function. The collocation method based on Chebyshev polynomials proposed by Erdogan and Gupta was used to solve the singular integral equation numerically. With the numerical solution, the effects of the geometrical and physical parameters on the stress intensity factor （SIF） were analyzed and the following conclusions were drawn： （a） The region affected by the interface or free surface varies with the material rigidity, and higher material rigidity will lead to bigger affected region. （b） The SIF of the crack in the affected region and parallel to the micro-discontinuous interface is lower than those of the weak discontinuous cases. Reducing the weak-discontinuity of the interface will be beneficial to decrease the SIF of the interface-parallel crack in the region affected by the interface. （c） The effect of the free surface on SIF is more remarkable than that of the interface, and the latter is still more notable than that of the material rigidity. When the effects of the interface and free surface are fixed, increase of the material rigidity will enhance the value of SIF.展开更多
The reliability of industrial installation requires minimum leakage of pressurized sealed joints during operation. At the design stage, the leakage behavior of the gasket must be one of the most important parameter in...The reliability of industrial installation requires minimum leakage of pressurized sealed joints during operation. At the design stage, the leakage behavior of the gasket must be one of the most important parameter in the gasket selection. The objective of the work presented in this paper is to develop an analytical leak rate prediction methodology used in gasketed joints. A pseudo analytical-experimental innovative approach was used to estimate the characteristics of the porous structure for the purpose of predicting accurate leak rate through gaskets with different fluids under conditions similar to those of operation. The analytical model assumes the flow to be continuum but employs a slip boundary condition on the leak path wall to determine the porosity parameters of the gasket. The analytical model results are validated and confronted against experimental data which were conducted under various conditions of fluid media, pressure, gasket stress and temperature. Two experimental test rigs fully automate that accurately reproduces the real leakage behavior of the gasketed joint have been developed to analyze the mechanical and thermal effects on the gasket flow regime. The gas leaks were measured with multi-gas mass spectrometers while liquid leaks were measure using a sophisticated detection system based on the pressure rise method.展开更多
Background:Parkinson’s disease(PD)is the second most common neurodegenerative disease after Alzheimer’s dementia.Mitochondrial dysfunction is involved in the pathology of PD.Coiled-coil-helix-coiled-coil-helix domai...Background:Parkinson’s disease(PD)is the second most common neurodegenerative disease after Alzheimer’s dementia.Mitochondrial dysfunction is involved in the pathology of PD.Coiled-coil-helix-coiled-coil-helix domain-containing 2(CHCHD2)was identified as associated with autosomal dominant PD.However,the mechanism of CHCHD2 in PD remains unclear.Methods:Short hairpin RNA(ShRNA)-mediated CHCHD2 knockdown or lentivirus-mediated CHCHD2 overexpression was performed to investigate the impact of CHCHD2 on mitochondrial morphology and function in neuronal tumor cell lines represented with human neuroblastoma(SHSY5Y)and HeLa cells.Blue-native polyacrylamide gel electrophoresis(PAGE)and two-dimensional sodium dodecyl sulfate-PAGE analysis were used to illustrate the role of CHCHD2 in mitochondrial contact site and cristae organizing system(MICOS).Co-immunoprecipitation and immunoblotting were used to address the interaction between CHCHD2 and Mic10.Serotype injection of adeno-associated vector-mediated CHCHD2 and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)administration were used to examine the influence of CHCHD2 in vivo.Results:We found that the overexpression of CHCHD2 can protect against methyl-4-phenylpyridinium(MPP+)-induced mitochondrial dysfunction and inhibit the loss of dopaminergic neurons in the MPTP-induced mouse model.Furthermore,we identified that CHCHD2 interacted with Mic10,and overexpression of CHCHD2 can protect against MPP+-induced MICOS impairment,while knockdown of CHCHD2 impaired the stability of MICOS.Conclusion:This study indicated that CHCHD2 could interact with Mic10 and maintain the stability of the MICOS complex,which contributes to protecting mitochondrial function in PD.展开更多
基金the BK 21 Program of South Korea and the National Natural Science Foundation of China(No.50574097).
文摘The problem considered is a mode Ⅲ crack lying parallel to the interface of an exponential-type functional graded material （FGM） strip bonded to a linear-type FGM substrate with infinite thickness. By applying the Fourier integral transform, the problem was reduced as a Cauchy singular integral equation with an unknown dislocation density function. The collocation method based on Chebyshev polynomials proposed by Erdogan and Gupta was used to solve the singular integral equation numerically. With the numerical solution, the effects of the geometrical and physical parameters on the stress intensity factor （SIF） were analyzed and the following conclusions were drawn： （a） The region affected by the interface or free surface varies with the material rigidity, and higher material rigidity will lead to bigger affected region. （b） The SIF of the crack in the affected region and parallel to the micro-discontinuous interface is lower than those of the weak discontinuous cases. Reducing the weak-discontinuity of the interface will be beneficial to decrease the SIF of the interface-parallel crack in the region affected by the interface. （c） The effect of the free surface on SIF is more remarkable than that of the interface, and the latter is still more notable than that of the material rigidity. When the effects of the interface and free surface are fixed, increase of the material rigidity will enhance the value of SIF.
文摘The reliability of industrial installation requires minimum leakage of pressurized sealed joints during operation. At the design stage, the leakage behavior of the gasket must be one of the most important parameter in the gasket selection. The objective of the work presented in this paper is to develop an analytical leak rate prediction methodology used in gasketed joints. A pseudo analytical-experimental innovative approach was used to estimate the characteristics of the porous structure for the purpose of predicting accurate leak rate through gaskets with different fluids under conditions similar to those of operation. The analytical model assumes the flow to be continuum but employs a slip boundary condition on the leak path wall to determine the porosity parameters of the gasket. The analytical model results are validated and confronted against experimental data which were conducted under various conditions of fluid media, pressure, gasket stress and temperature. Two experimental test rigs fully automate that accurately reproduces the real leakage behavior of the gasketed joint have been developed to analyze the mechanical and thermal effects on the gasket flow regime. The gas leaks were measured with multi-gas mass spectrometers while liquid leaks were measure using a sophisticated detection system based on the pressure rise method.
基金supported by research grants from the National Natural Science Foundation of China(Nos.81901282,81870992,82071444)the Nature Science Foundation of Guangdong Province(Nos.2019A1515011189,2020A1515010985)the Technology Project of Guangzhou(Nos.202102020029,2019ZD09).
文摘Background:Parkinson’s disease(PD)is the second most common neurodegenerative disease after Alzheimer’s dementia.Mitochondrial dysfunction is involved in the pathology of PD.Coiled-coil-helix-coiled-coil-helix domain-containing 2(CHCHD2)was identified as associated with autosomal dominant PD.However,the mechanism of CHCHD2 in PD remains unclear.Methods:Short hairpin RNA(ShRNA)-mediated CHCHD2 knockdown or lentivirus-mediated CHCHD2 overexpression was performed to investigate the impact of CHCHD2 on mitochondrial morphology and function in neuronal tumor cell lines represented with human neuroblastoma(SHSY5Y)and HeLa cells.Blue-native polyacrylamide gel electrophoresis(PAGE)and two-dimensional sodium dodecyl sulfate-PAGE analysis were used to illustrate the role of CHCHD2 in mitochondrial contact site and cristae organizing system(MICOS).Co-immunoprecipitation and immunoblotting were used to address the interaction between CHCHD2 and Mic10.Serotype injection of adeno-associated vector-mediated CHCHD2 and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)administration were used to examine the influence of CHCHD2 in vivo.Results:We found that the overexpression of CHCHD2 can protect against methyl-4-phenylpyridinium(MPP+)-induced mitochondrial dysfunction and inhibit the loss of dopaminergic neurons in the MPTP-induced mouse model.Furthermore,we identified that CHCHD2 interacted with Mic10,and overexpression of CHCHD2 can protect against MPP+-induced MICOS impairment,while knockdown of CHCHD2 impaired the stability of MICOS.Conclusion:This study indicated that CHCHD2 could interact with Mic10 and maintain the stability of the MICOS complex,which contributes to protecting mitochondrial function in PD.
