Time effect of wet drilling pile is investigated through the static load experiment on pile No. 22 of Guanhe Bridge. Post-grouting under pile tip is adopted in the project. To study the bearing performance of the pile...Time effect of wet drilling pile is investigated through the static load experiment on pile No. 22 of Guanhe Bridge. Post-grouting under pile tip is adopted in the project. To study the bearing performance of the pile, the self-balanced method is used and two load cells are assembled in the pile body. The experiments are carried out before and after post-grouting. The upper part of the pile is not influenced by post-grouting under the pile tip. Experimental results of the upper part of the pile show that the bearing capacity and the rigidity of wet drilling pile increase with time passing on. Analysis results show the time effect of wet drilling pile is influenced by many factors, such as alteration of stress field around pile, characteristics of soil around pile, variety of mud cake, and property of residue under pile tip.展开更多
Based on the characteristics of pile-soil interaction and the Mohr-Coulomb strength theory,a new method of determining the side friction at a pile-soil interaction is proposed.Combined with the actual engineering case...Based on the characteristics of pile-soil interaction and the Mohr-Coulomb strength theory,a new method of determining the side friction at a pile-soil interaction is proposed.Combined with the actual engineering cases,the effectiveness of the analogue test method is verified by comparing it with the traditional anchor pile method and self-balanced method.Taking the self-balanced test of the bridge pile foundation in the Songhua River as an example,the conversion factor of sandy soil and weathered mudstone are confirmed by the analogue test method.The results show that the conversion factor of sandy soil and weathered mudstone in the Songhua River area should consider the geological conditions and the construction technology,etc.The standard values are relatively conservative.It is suggested that the engineering application should be properly revised.The recommended range of the conversion factor of sandy soil in this area is 0.65 to 0.85,and that of weathered mudstone is 1.0.展开更多
AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane. METHODS: Hepatocytes freshly isolated f...AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane. METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V) for 30 or 60 min, followed by 5 or 10 min of reoxygenation, with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated. RESULTS: During 30 min of anoxia, the energy charge and total adenine nudeotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC. In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nudeotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nudeotide greatly decreased during anoxia, with partial and no reversal by reoxygenation, respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nudeotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1 MAC halothane. CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nudeotide during short (reversible) or long (irreversible) anoxia.展开更多
OBJECTIVE: To investigate the underlying mechanism of reduced myocardial ischemia-reperfusion (I/R) injury in rats using the traditionalTibetan medicine Sanweitanxiang powder (SWTX). METHODS: Rats were randomly divide...OBJECTIVE: To investigate the underlying mechanism of reduced myocardial ischemia-reperfusion (I/R) injury in rats using the traditionalTibetan medicine Sanweitanxiang powder (SWTX). METHODS: Rats were randomly divided into six groups (n=10) as follows: (a) propranolol dinitrate control group, given propranolol dinitrate 0.02 g/kg for 10 days before I/R, (b) SWTX with a high dose group, given SWTX 1.5 g/kg for 10 days before I/R, (c) SWTX with a medium dose group, given SWTX 1.25 g/kg for 10 days before I/R, (d) sham group (Sham), in which the rat heart was exposed by pericardiotomy but without I/R, (e) SWTX with a low dose group, given SWTX 1.0 g/kg for 10 days before I/R, and (f) I/R injury group. Rats were intragastrically pretreated with propranolol dinitrate orSWTX. After that, the operation to cause ischemia and reperfusion was conducted.The histopathologic changes of rat hearts were observed by hematoxylin and eosin staining and transmission electron microscopy. Ca2+ homeostasis protein expression was determined by western blot. RESULTS: After SWTX pretreatment, the development of ultrastructural pathological changes from IR injury was attenuated. A decrease in the expression of B-cell lymphoma 2 associated X protein, and an increase in the expression of B-cell lymphoma 2 were observed. An increased activation of extracellular signal regulated kinases were found. Compared with the sham group, the expression of sarcoplasmic reticulum calcium-ATPase, phospholamban, and calsequestrin were all up-regulated after pretreatment with SWTX. CONCLUSION: The protective mechanism of SWTX pretreatment on myocardial I/R injury might be related to its effect on maintaining the balance of calcium homeostasis in rat heart.展开更多
文摘Time effect of wet drilling pile is investigated through the static load experiment on pile No. 22 of Guanhe Bridge. Post-grouting under pile tip is adopted in the project. To study the bearing performance of the pile, the self-balanced method is used and two load cells are assembled in the pile body. The experiments are carried out before and after post-grouting. The upper part of the pile is not influenced by post-grouting under the pile tip. Experimental results of the upper part of the pile show that the bearing capacity and the rigidity of wet drilling pile increase with time passing on. Analysis results show the time effect of wet drilling pile is influenced by many factors, such as alteration of stress field around pile, characteristics of soil around pile, variety of mud cake, and property of residue under pile tip.
基金The National Key Research and Development Program(No.2017YFC0703408)the National Natural Science Foundation of China(No.51478109,51678145,51878160)
文摘Based on the characteristics of pile-soil interaction and the Mohr-Coulomb strength theory,a new method of determining the side friction at a pile-soil interaction is proposed.Combined with the actual engineering cases,the effectiveness of the analogue test method is verified by comparing it with the traditional anchor pile method and self-balanced method.Taking the self-balanced test of the bridge pile foundation in the Songhua River as an example,the conversion factor of sandy soil and weathered mudstone are confirmed by the analogue test method.The results show that the conversion factor of sandy soil and weathered mudstone in the Songhua River area should consider the geological conditions and the construction technology,etc.The standard values are relatively conservative.It is suggested that the engineering application should be properly revised.The recommended range of the conversion factor of sandy soil in this area is 0.65 to 0.85,and that of weathered mudstone is 1.0.
基金Supported by the National Natural Science Foundation of China, No. 39900140
文摘AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane. METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V) for 30 or 60 min, followed by 5 or 10 min of reoxygenation, with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated. RESULTS: During 30 min of anoxia, the energy charge and total adenine nudeotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC. In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nudeotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nudeotide greatly decreased during anoxia, with partial and no reversal by reoxygenation, respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nudeotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1 MAC halothane. CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nudeotide during short (reversible) or long (irreversible) anoxia.
基金Supported by a Grant from the National Natural Sciences Foundation of China(No.81060368)
文摘OBJECTIVE: To investigate the underlying mechanism of reduced myocardial ischemia-reperfusion (I/R) injury in rats using the traditionalTibetan medicine Sanweitanxiang powder (SWTX). METHODS: Rats were randomly divided into six groups (n=10) as follows: (a) propranolol dinitrate control group, given propranolol dinitrate 0.02 g/kg for 10 days before I/R, (b) SWTX with a high dose group, given SWTX 1.5 g/kg for 10 days before I/R, (c) SWTX with a medium dose group, given SWTX 1.25 g/kg for 10 days before I/R, (d) sham group (Sham), in which the rat heart was exposed by pericardiotomy but without I/R, (e) SWTX with a low dose group, given SWTX 1.0 g/kg for 10 days before I/R, and (f) I/R injury group. Rats were intragastrically pretreated with propranolol dinitrate orSWTX. After that, the operation to cause ischemia and reperfusion was conducted.The histopathologic changes of rat hearts were observed by hematoxylin and eosin staining and transmission electron microscopy. Ca2+ homeostasis protein expression was determined by western blot. RESULTS: After SWTX pretreatment, the development of ultrastructural pathological changes from IR injury was attenuated. A decrease in the expression of B-cell lymphoma 2 associated X protein, and an increase in the expression of B-cell lymphoma 2 were observed. An increased activation of extracellular signal regulated kinases were found. Compared with the sham group, the expression of sarcoplasmic reticulum calcium-ATPase, phospholamban, and calsequestrin were all up-regulated after pretreatment with SWTX. CONCLUSION: The protective mechanism of SWTX pretreatment on myocardial I/R injury might be related to its effect on maintaining the balance of calcium homeostasis in rat heart.