Based on the uniaxial compression creep experiments conducted on bauxite sandstone obtained from Sanmenxia,typical creep experiment curves were obtained.From the characteristics of strain component of creep curves,the...Based on the uniaxial compression creep experiments conducted on bauxite sandstone obtained from Sanmenxia,typical creep experiment curves were obtained.From the characteristics of strain component of creep curves,the creep strain is composed of instantaneous elastic strain,ε（me）,instantaneous plastic strain,ε（mp）,viscoelastic strain,ε（ce）,and viscoplastic strain,ε（cp）.Based on the characteristics of instantaneous plastic strain,a new element of instantaneous plastic rheology was introduced,instantaneous plastic modulus was defined,and the modified Burgers model was established.Then identification of direct screening method in this model was completed.According to the mechanical properties of rheological elements,one- and three-dimensional creep equations in different stress levels were obtained.One-dimensional model parameters were identified by the method of least squares,and in the process of computation,Gauss-Newton iteration method was applied.Finally,by fitting the experimental curves,the correctness of direct method model was verified,then the examination of posterior exclusive method of the model was accomplished.The results showed that in the improved Burgers models,the rheological characteristics of sandstone are embodied properly,microscopic analysis of creep curves is also achieved,and the correctness of comprehensive identification method of rheological model is verified.展开更多
Strain rate effects on the stress-strain behavior of sand were investigated by performing special plane strain and triaxial compression tests on saturated and air-dried sand specimens. In these tests, the loading stra...Strain rate effects on the stress-strain behavior of sand were investigated by performing special plane strain and triaxial compression tests on saturated and air-dried sand specimens. In these tests, the loading strain rate was changed many times by a factor of up to 1 000 during otherwise monotonous loading at a constant axial strain rate. Test results show that the stress jump upon a stepwise change in the strain rate decays with an increase in the irreversible strain when monotonous loading continues at the changed strain rate and the amount of stress jump is essentially proportional to the instantaneous stress. Based on the amount of these stress jumps, a parameter fl called the rate-sensitivity coefficient is introduced to represent the quantity of the observed viscous properties of sand, which equals 0.021 3 and 0.024 2 respectively for Hostun and Toyoura sands. Further analyses on the results indicate that the effect of the presence of pore water is deemed to be negligible with sand and the fl value is rather independent of loading method, wet condition and confining pressure.展开更多
According to a linear equation of the laser intensity of single-mode laser with input signal, we compute the generalized signal-to-noise ratio （GSNR） in the instantaneous-state of the single-mode laser, which is dri...According to a linear equation of the laser intensity of single-mode laser with input signal, we compute the generalized signal-to-noise ratio （GSNR） in the instantaneous-state of the single-mode laser, which is driven by two colored noises and correlated in the form of an e-exponential function. We detect that the stochastic resonance （SR） also occurs on instantaneous state at any time. Furthermore we discuss the GSNR trend to stable state in three different forms when taking different signal frequencies.展开更多
In the present study,we aimed to investigate the effect of puromycin aminonucleoside(PAN)on the expression and distribution of transient receptor potential canonical 6(TRPC6)of murine podocytes and further study the p...In the present study,we aimed to investigate the effect of puromycin aminonucleoside(PAN)on the expression and distribution of transient receptor potential canonical 6(TRPC6)of murine podocytes and further study the protective mechanism of fluvastatin on podocyte injury by TRPC6 in vitro.Podocytes were treated by PAN at different doses and at different time points.The expressions of TRPC6 at mRNA and protein levels were assessed.An immunofluorescent assay was used to observe the distribution of TRPC6.Cultured podocytes were then divided into four groups.The expressions of TRPC6 at mRNA and protein levels were measured.The intracellular calcium concentration of podocytes was measured with a laser-scanning confocal microscope.The paracellular permeability to BSA was evaluated using Millicell-PCF Inserts.The expressions of TRPC6 at mRNA and protein levels were increased in a dose and time-dependent manner after exposure to PAN.Immunofluorescence showed that the expression intensity of TRPC6 was significantly increased,and the distribution of TRPC6 was changed after PAN was applied to podocytes.With fluvastatin intervention,PAN-induced up-regulation of TRPC6 was significantly reversed.The ratio of the peak value of intracellular calcium to the basic calcium value in the PAN group was significantly higher after TRPC6 was activated by OAG,while it is obviously reversed under the action of fluvastatin.The podocyte permeability was significantly increased after 48 h of PAN treatment,while the above situation was effectively improved after fluvastatin intervention.The changes of distribution and expression of TRPC6 were related to podocyte injury induced by PAN.Fluvastatin could exert its protective effects on podocytes by down-regulating TRPC6.展开更多
基金Projects (51174228,51274249) supported by the National Natural Science Foundation of China
文摘Based on the uniaxial compression creep experiments conducted on bauxite sandstone obtained from Sanmenxia,typical creep experiment curves were obtained.From the characteristics of strain component of creep curves,the creep strain is composed of instantaneous elastic strain,ε（me）,instantaneous plastic strain,ε（mp）,viscoelastic strain,ε（ce）,and viscoplastic strain,ε（cp）.Based on the characteristics of instantaneous plastic strain,a new element of instantaneous plastic rheology was introduced,instantaneous plastic modulus was defined,and the modified Burgers model was established.Then identification of direct screening method in this model was completed.According to the mechanical properties of rheological elements,one- and three-dimensional creep equations in different stress levels were obtained.One-dimensional model parameters were identified by the method of least squares,and in the process of computation,Gauss-Newton iteration method was applied.Finally,by fitting the experimental curves,the correctness of direct method model was verified,then the examination of posterior exclusive method of the model was accomplished.The results showed that in the improved Burgers models,the rheological characteristics of sandstone are embodied properly,microscopic analysis of creep curves is also achieved,and the correctness of comprehensive identification method of rheological model is verified.
基金Project(50679056) supported by the National Natural Science Foundation of ChinaProject(06-0378) supported by Program for NewCentury Excellent Talents in University+1 种基金Project(05SG25) supported by the "Dawn" Program of Shanghai Education Commission, ChinaProject(B308) supported by the Shanghai Leading Academic Discipline, China
文摘Strain rate effects on the stress-strain behavior of sand were investigated by performing special plane strain and triaxial compression tests on saturated and air-dried sand specimens. In these tests, the loading strain rate was changed many times by a factor of up to 1 000 during otherwise monotonous loading at a constant axial strain rate. Test results show that the stress jump upon a stepwise change in the strain rate decays with an increase in the irreversible strain when monotonous loading continues at the changed strain rate and the amount of stress jump is essentially proportional to the instantaneous stress. Based on the amount of these stress jumps, a parameter fl called the rate-sensitivity coefficient is introduced to represent the quantity of the observed viscous properties of sand, which equals 0.021 3 and 0.024 2 respectively for Hostun and Toyoura sands. Further analyses on the results indicate that the effect of the presence of pore water is deemed to be negligible with sand and the fl value is rather independent of loading method, wet condition and confining pressure.
基金The project supported by National Natural Science Foundation of Chain under Grant No. 10275025 and Natural Scicnce Foundation of Xiangfan University
文摘According to a linear equation of the laser intensity of single-mode laser with input signal, we compute the generalized signal-to-noise ratio （GSNR） in the instantaneous-state of the single-mode laser, which is driven by two colored noises and correlated in the form of an e-exponential function. We detect that the stochastic resonance （SR） also occurs on instantaneous state at any time. Furthermore we discuss the GSNR trend to stable state in three different forms when taking different signal frequencies.
基金National Natural Science Foundation of China(Grant No.81400333)。
文摘In the present study,we aimed to investigate the effect of puromycin aminonucleoside(PAN)on the expression and distribution of transient receptor potential canonical 6(TRPC6)of murine podocytes and further study the protective mechanism of fluvastatin on podocyte injury by TRPC6 in vitro.Podocytes were treated by PAN at different doses and at different time points.The expressions of TRPC6 at mRNA and protein levels were assessed.An immunofluorescent assay was used to observe the distribution of TRPC6.Cultured podocytes were then divided into four groups.The expressions of TRPC6 at mRNA and protein levels were measured.The intracellular calcium concentration of podocytes was measured with a laser-scanning confocal microscope.The paracellular permeability to BSA was evaluated using Millicell-PCF Inserts.The expressions of TRPC6 at mRNA and protein levels were increased in a dose and time-dependent manner after exposure to PAN.Immunofluorescence showed that the expression intensity of TRPC6 was significantly increased,and the distribution of TRPC6 was changed after PAN was applied to podocytes.With fluvastatin intervention,PAN-induced up-regulation of TRPC6 was significantly reversed.The ratio of the peak value of intracellular calcium to the basic calcium value in the PAN group was significantly higher after TRPC6 was activated by OAG,while it is obviously reversed under the action of fluvastatin.The podocyte permeability was significantly increased after 48 h of PAN treatment,while the above situation was effectively improved after fluvastatin intervention.The changes of distribution and expression of TRPC6 were related to podocyte injury induced by PAN.Fluvastatin could exert its protective effects on podocytes by down-regulating TRPC6.
