The three-dimensional （3D） deformation effect of the slope engineering under the step-by-step excavation for the Antaibao surface mine was analyzed using the FLAC^3D technique. An optimal excavated scheme with a rel...The three-dimensional （3D） deformation effect of the slope engineering under the step-by-step excavation for the Antaibao surface mine was analyzed using the FLAC^3D technique. An optimal excavated scheme with a relatively steeper slope angle of 47° instead of 30° was successfully implemented at the west wall in the geological section 73200 of the mine area, where the 3D effect of the nonlinear large deformation of the slope was taken into account. Based on the above research conclusion, put forward the countermeasures of shortening mining length, excavating by different regions, timely foot backfilling to protect the excavated slope, and monitoring and feedback adjustment by studying the nonlinear effect. The results show that these countermeasures are effective in controlling maximum deformation and increasing the stability of the slope.展开更多
Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior o...Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs,the geological feature of reservoirs in Bohai Bay Basin is studied firstly,including the reservoir vertical distribution feature and the heterogeneous lithology.Then,hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system.Results show the hydraulic fractures generated in the reservoirs are mostly in X shape.The cause of X-shaped hydraulic fractures in this study is mainly ascribed to(I)the reservoir heterogeneity and(II)the stress shadow effect of two close hydraulic fractures propagating in the same orientation,which is confirmed by the following numerical simulation and related research in detail.This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs.展开更多
Background Hyperhomocysteinemia （HHcy）-mediated dysfunction of endothelial NO system is an important mechanism for atherosclerotic pathogenesis. Dimethylarginine dimethylaminohydrolase （DDAH） is the key enzyme for...Background Hyperhomocysteinemia （HHcy）-mediated dysfunction of endothelial NO system is an important mechanism for atherosclerotic pathogenesis. Dimethylarginine dimethylaminohydrolase （DDAH） is the key enzyme for degrading asymmetric dimethylarginine （ADMA）, which is an endogenous inhibitor of endothelial nitric oxide （NO） synthase （eNOS）. This study was designed to investigate whether the dysfunction of endothelial NO system originates from HHcy-mediated aberrant methylation modification in promotor region of DDAH2 gene. Methods Human umbilical vein endothelial cells （HUVECs） were cultured to the third generation and treated with homocysteine （Hcy） at different concentrations （0, 10, 30, 100, and 300 μmol/L） for 72 hours. The methylation pattern in promoter region CpG island of DDAH2 gene was analyzed by nested methylation-specific PCR （nMSP）. The mRNA expression of eNOS gene and DDAH2 gene was detected by semi-quantitative RT-PCR. The activity of DDAH2 and eNOS in cells, and the concentrations of ADMA and NO in culture medium were assayed respectively. Results Mild increased concentration of Hcy （10 and 30 μmol/L） induced hypomethylation, while high concentration of Hcy （100 and 300 μmol/L） induced hypermethylation in the promoter CpG island of DDAH2 gene. The mRNA expression of DDAH2 increased in mild enhanced concentration of Hcy, and decreased in high concentration of Hcy correspondingly. The inhibition of DDAH2 activity, the increase of ADMA concentration, the reduction of eNOS activity and the decrease of NO production were all consistently relevant to the alteration of Hcy concentration. Conclusion The increased concentration of Hcy induced aberrant methylation pattern in promotor region of DDAH2 gene and the successive alterations in DDAH/ADMA/NOS/NO pathway, which showed highly relevant and dose-effect relationship. The results suggested that the dysfunction of endothelial NO system induced by HHcy could be partially originated from Hcy-mediated aberrant methylation in DDAH2 gene.展开更多
Glutathione （GSH） is the principal non-protein thiol responsible for maintaining intracellular redox status and protecting cells against oxidative/ nitrosative stresses. In the biological system, some GSH is bound t...Glutathione （GSH） is the principal non-protein thiol responsible for maintaining intracellular redox status and protecting cells against oxidative/ nitrosative stresses. In the biological system, some GSH is bound to proteins, and others exist freely, including the reduced glutathione and oxidized glutathione （GSSG）. Generally it is in a steady redox state for GSH/GSSG couple to participate in a variety of physiological functions. Earlier studies showed that chemically induced oxidative stress in vivo in rats resulted in increased GSSG and decreased GSH/GSSG ratio. The impairment of the glutathione homeostasis represents an indicator of tissue oxidative stresss status in human subjects.展开更多
Background Atherosclerosis is a chronic inflammatory disease. Accumulated evidences suggest a deep involvement of oxidative damage in the development of atherosclerosis, but little is discussed over the relationship b...Background Atherosclerosis is a chronic inflammatory disease. Accumulated evidences suggest a deep involvement of oxidative damage in the development of atherosclerosis, but little is discussed over the relationship between plasma glutathione redox status as the most important intrinsic antioxidant defensive mechanism and the atherosclerosis. Methods A total of 132 patients suspected with atherosclerosis were assigned to three groups by high frequency ultrasonic examination of the carotid artery. With the thickness of intima of the carotid artery as an index of degree of atherosclerosis progression, 56 were included in plaque-forming group （A）, 42 in carotid artery intima-thickening group （B）, and 34 in normal carotid artery intima-thickness group （C）. All patients were subjected to the measurement of plasma glutathione （GSH） （reduced form GSH and oxidized form GSSG）, nicotinamide adenine dinucleotide phosphate （NADP） （reduced form NADPH and oxidized form NADP^＋）, oxidized low density lipoprotein （oxLDL）, and malondialdehyde （MDA） The GSH/GSSG and NADPH/NADP^＋ redox potentials were calculated according to the Nernst equation, and their correlation with intima thickness and oxLDL was analyzed. Results With the thickening of artery intima （from group C to A）, GSH concentration and the ratio of GSH/GSSG gradually reduced, and GSSG and GSH/GSSG redox potential gradually increased （more positive） （P 〈0.05）. The NADPH and NADPH/NADP^＋ redox status also showed similar but milder changes. The products of oxidative stress oxLDL and MDA increased significantly along with the thickening of artery intima （P 〈0.05）. The analysis of the relationship between GSH/GSSG redox potential, intima thickness, and oxLDL showed positive correlations （P 〈0.05）. The plasma GSH/GSSG redox status was positively correlated with the intima thickness of the carotid artery and the oxidized injury of LDL. The redox status shifted to oxidizing direction along with the intima thickening and plaque-forming. Conclusion Elevated peroxidative glutathione redox status was deeply implicated in atherosclerosis progressing, and it may be a sensitive and reliable index for monitoring oxidative status in atherosclerosis.展开更多
基金Supported by the National Natural Science Foundation of China(10572008)the Natural Science Foundation of Beijing(3063019)Doctor Foundation of Yanshan University(B245)
文摘The three-dimensional （3D） deformation effect of the slope engineering under the step-by-step excavation for the Antaibao surface mine was analyzed using the FLAC^3D technique. An optimal excavated scheme with a relatively steeper slope angle of 47° instead of 30° was successfully implemented at the west wall in the geological section 73200 of the mine area, where the 3D effect of the nonlinear large deformation of the slope was taken into account. Based on the above research conclusion, put forward the countermeasures of shortening mining length, excavating by different regions, timely foot backfilling to protect the excavated slope, and monitoring and feedback adjustment by studying the nonlinear effect. The results show that these countermeasures are effective in controlling maximum deformation and increasing the stability of the slope.
基金Projects(51879041,51774112,U1810203)supported by the National Natural Science Foundation of ChinaProject(2020M672224)supported by the China Postdoctoral Science FoundationProject(B2020-41)supported by the Doctoral Fund of Henan Polytechnic University,China。
文摘Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs,the geological feature of reservoirs in Bohai Bay Basin is studied firstly,including the reservoir vertical distribution feature and the heterogeneous lithology.Then,hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system.Results show the hydraulic fractures generated in the reservoirs are mostly in X shape.The cause of X-shaped hydraulic fractures in this study is mainly ascribed to(I)the reservoir heterogeneity and(II)the stress shadow effect of two close hydraulic fractures propagating in the same orientation,which is confirmed by the following numerical simulation and related research in detail.This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs.
基金the grant from the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20050610050).
文摘Background Hyperhomocysteinemia （HHcy）-mediated dysfunction of endothelial NO system is an important mechanism for atherosclerotic pathogenesis. Dimethylarginine dimethylaminohydrolase （DDAH） is the key enzyme for degrading asymmetric dimethylarginine （ADMA）, which is an endogenous inhibitor of endothelial nitric oxide （NO） synthase （eNOS）. This study was designed to investigate whether the dysfunction of endothelial NO system originates from HHcy-mediated aberrant methylation modification in promotor region of DDAH2 gene. Methods Human umbilical vein endothelial cells （HUVECs） were cultured to the third generation and treated with homocysteine （Hcy） at different concentrations （0, 10, 30, 100, and 300 μmol/L） for 72 hours. The methylation pattern in promoter region CpG island of DDAH2 gene was analyzed by nested methylation-specific PCR （nMSP）. The mRNA expression of eNOS gene and DDAH2 gene was detected by semi-quantitative RT-PCR. The activity of DDAH2 and eNOS in cells, and the concentrations of ADMA and NO in culture medium were assayed respectively. Results Mild increased concentration of Hcy （10 and 30 μmol/L） induced hypomethylation, while high concentration of Hcy （100 and 300 μmol/L） induced hypermethylation in the promoter CpG island of DDAH2 gene. The mRNA expression of DDAH2 increased in mild enhanced concentration of Hcy, and decreased in high concentration of Hcy correspondingly. The inhibition of DDAH2 activity, the increase of ADMA concentration, the reduction of eNOS activity and the decrease of NO production were all consistently relevant to the alteration of Hcy concentration. Conclusion The increased concentration of Hcy induced aberrant methylation pattern in promotor region of DDAH2 gene and the successive alterations in DDAH/ADMA/NOS/NO pathway, which showed highly relevant and dose-effect relationship. The results suggested that the dysfunction of endothelial NO system induced by HHcy could be partially originated from Hcy-mediated aberrant methylation in DDAH2 gene.
文摘Glutathione （GSH） is the principal non-protein thiol responsible for maintaining intracellular redox status and protecting cells against oxidative/ nitrosative stresses. In the biological system, some GSH is bound to proteins, and others exist freely, including the reduced glutathione and oxidized glutathione （GSSG）. Generally it is in a steady redox state for GSH/GSSG couple to participate in a variety of physiological functions. Earlier studies showed that chemically induced oxidative stress in vivo in rats resulted in increased GSSG and decreased GSH/GSSG ratio. The impairment of the glutathione homeostasis represents an indicator of tissue oxidative stresss status in human subjects.
文摘Background Atherosclerosis is a chronic inflammatory disease. Accumulated evidences suggest a deep involvement of oxidative damage in the development of atherosclerosis, but little is discussed over the relationship between plasma glutathione redox status as the most important intrinsic antioxidant defensive mechanism and the atherosclerosis. Methods A total of 132 patients suspected with atherosclerosis were assigned to three groups by high frequency ultrasonic examination of the carotid artery. With the thickness of intima of the carotid artery as an index of degree of atherosclerosis progression, 56 were included in plaque-forming group （A）, 42 in carotid artery intima-thickening group （B）, and 34 in normal carotid artery intima-thickness group （C）. All patients were subjected to the measurement of plasma glutathione （GSH） （reduced form GSH and oxidized form GSSG）, nicotinamide adenine dinucleotide phosphate （NADP） （reduced form NADPH and oxidized form NADP^＋）, oxidized low density lipoprotein （oxLDL）, and malondialdehyde （MDA） The GSH/GSSG and NADPH/NADP^＋ redox potentials were calculated according to the Nernst equation, and their correlation with intima thickness and oxLDL was analyzed. Results With the thickening of artery intima （from group C to A）, GSH concentration and the ratio of GSH/GSSG gradually reduced, and GSSG and GSH/GSSG redox potential gradually increased （more positive） （P 〈0.05）. The NADPH and NADPH/NADP^＋ redox status also showed similar but milder changes. The products of oxidative stress oxLDL and MDA increased significantly along with the thickening of artery intima （P 〈0.05）. The analysis of the relationship between GSH/GSSG redox potential, intima thickness, and oxLDL showed positive correlations （P 〈0.05）. The plasma GSH/GSSG redox status was positively correlated with the intima thickness of the carotid artery and the oxidized injury of LDL. The redox status shifted to oxidizing direction along with the intima thickening and plaque-forming. Conclusion Elevated peroxidative glutathione redox status was deeply implicated in atherosclerosis progressing, and it may be a sensitive and reliable index for monitoring oxidative status in atherosclerosis.
