Heterogeneous catalysts with ultrafine or nano particle size have currently attracted considerable attentions in the chemical and petrochemical production processes, but their large-scale applications remain challengi...Heterogeneous catalysts with ultrafine or nano particle size have currently attracted considerable attentions in the chemical and petrochemical production processes, but their large-scale applications remain challenging because of difficulties associated with their efficient separation from the reaction slurry. A porous ceramic membrane reactor has emerged as a promising method to solve the problem concerning catalysts separation in situ from the reaction mixture and make the production process continuous in heterogeneous catalysis. This article presents a review of the present progress on porous ceramic membrane reactors for heterogeneous catalysis, which covers classification of configurations of porous ceramic membrane reactor, major considerations and some important industrial applications. A special emphasis is paid to major considerations in term of application-oriented ceramic membrane design, optimization of ceramic membrane reactor performance and membrane fouling mechanism. Finally, brief concluding remarks on porous ceramic membrane reactors are given and possible future research interests are also outlined.展开更多
AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCT...AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCTs） co- mparing hemihepatic vascular occlusion and total he- patic inflow occlusion were included by a systematic literature search. Two authors independently assessed the trials for inclusion and extracted the data. A meta- analysis was conducted to estimate blood loss, transfu- sion requirement, and liver injury based on the levels of aspartate aminotransferase （AST） and alanine arni- notransferase （ALT）. Either the fixed effects model or random effects model was used. RESULTS- Four RCTs including 338 patients met the predefined inclusion criteria. A total of 167 patients were treated with THO and 171 with HHO. Metaanalysis of AST levels on postoperative day 1 indicated higher levels in the THO group with weighted mean dif- ference （WMD） 342.27; 95% confidence intervals （CI） 217.28-467.26; P = 0.00001; I2 = 16%. Meta-analysis showed no significant difference between THO group and HHO group on blood loss, transfusion requirement, mortality, morbidity, operating time, ischemic duration, hospital stay, ALT levels on postoperative day 1, 3 and 7 and AST levels on postoperative day 3 and 7. CONCLUSION： Hemihepatic vascular occlusion does not offer satisfying benefit to the patients undergoing hepatic resection. However, they have less liver injury after liver resections.展开更多
Influence of confining pressure from 0 to 28 MPa, which acts on the two lateral edges of rock specimen in plane strain compression, on the shear failure processes and patterns as well as on the macroscopically mechani...Influence of confining pressure from 0 to 28 MPa, which acts on the two lateral edges of rock specimen in plane strain compression, on the shear failure processes and patterns as well as on the macroscopically mechanical responses were numerically modeled by use of FLAC. A material imperfection with lower strength in comparison with the intact rock, which is close to the lower-left corner of the specimen, was prescribed. In elastic stage, the adopted constitutive relation of rock was linear elastic; in strain-softening stage, a composite Mohr-Coulomb criterion with tension cut-off and a post-peak linear constitutive relation were adopted. The numerical results show that with an increase of confining pressure the peak strength of axial stress-axial strain curve and the corresponding axial strain linearly increase; the residual strength and the stress drop from the peak strength to the residual strength increase; the failure modes of rock transform form the multiple shear bands close to the loading end of the specimen （confining pressure=0-0.1 MPa）, to the conjugate shear bands （0.5-2.0 MPa）, and then to the single shear band （4-28 MPa）. Once the tip of the band reaches the loading end of the specimen, the direction of the band changes so that the reflection of the band occurs. At higher confining pressure, the new-formed shear band does not intersect the imperfection, bringing extreme difficulties in prediction of the failure of rock structure, such as rock burst. The present results enhance the understanding of the shear failure processes and patterns of rock specimen in higher confining pressure and higher loading strain rate.展开更多
基金Supported by the National Natural Science Foundation of China （20990222, 21106061）, the National Basic Research Program of China （2009CB623406）, the National Key Science and Technology Program of China （2011BAE07B05） and the Natural Science Foundation of Jiangsu Province, China （BK2010549, BK2009021）.
文摘Heterogeneous catalysts with ultrafine or nano particle size have currently attracted considerable attentions in the chemical and petrochemical production processes, but their large-scale applications remain challenging because of difficulties associated with their efficient separation from the reaction slurry. A porous ceramic membrane reactor has emerged as a promising method to solve the problem concerning catalysts separation in situ from the reaction mixture and make the production process continuous in heterogeneous catalysis. This article presents a review of the present progress on porous ceramic membrane reactors for heterogeneous catalysis, which covers classification of configurations of porous ceramic membrane reactor, major considerations and some important industrial applications. A special emphasis is paid to major considerations in term of application-oriented ceramic membrane design, optimization of ceramic membrane reactor performance and membrane fouling mechanism. Finally, brief concluding remarks on porous ceramic membrane reactors are given and possible future research interests are also outlined.
文摘AIM： To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion （HHO） compared with total hepatic inflow occlusion （THO）. METHODS： Randomized controlled trials （RCTs） co- mparing hemihepatic vascular occlusion and total he- patic inflow occlusion were included by a systematic literature search. Two authors independently assessed the trials for inclusion and extracted the data. A meta- analysis was conducted to estimate blood loss, transfu- sion requirement, and liver injury based on the levels of aspartate aminotransferase （AST） and alanine arni- notransferase （ALT）. Either the fixed effects model or random effects model was used. RESULTS- Four RCTs including 338 patients met the predefined inclusion criteria. A total of 167 patients were treated with THO and 171 with HHO. Metaanalysis of AST levels on postoperative day 1 indicated higher levels in the THO group with weighted mean dif- ference （WMD） 342.27; 95% confidence intervals （CI） 217.28-467.26; P = 0.00001; I2 = 16%. Meta-analysis showed no significant difference between THO group and HHO group on blood loss, transfusion requirement, mortality, morbidity, operating time, ischemic duration, hospital stay, ALT levels on postoperative day 1, 3 and 7 and AST levels on postoperative day 3 and 7. CONCLUSION： Hemihepatic vascular occlusion does not offer satisfying benefit to the patients undergoing hepatic resection. However, they have less liver injury after liver resections.
基金Supported by the National Natural Science Foundation of China(50490275,50309004)
文摘Influence of confining pressure from 0 to 28 MPa, which acts on the two lateral edges of rock specimen in plane strain compression, on the shear failure processes and patterns as well as on the macroscopically mechanical responses were numerically modeled by use of FLAC. A material imperfection with lower strength in comparison with the intact rock, which is close to the lower-left corner of the specimen, was prescribed. In elastic stage, the adopted constitutive relation of rock was linear elastic; in strain-softening stage, a composite Mohr-Coulomb criterion with tension cut-off and a post-peak linear constitutive relation were adopted. The numerical results show that with an increase of confining pressure the peak strength of axial stress-axial strain curve and the corresponding axial strain linearly increase; the residual strength and the stress drop from the peak strength to the residual strength increase; the failure modes of rock transform form the multiple shear bands close to the loading end of the specimen （confining pressure=0-0.1 MPa）, to the conjugate shear bands （0.5-2.0 MPa）, and then to the single shear band （4-28 MPa）. Once the tip of the band reaches the loading end of the specimen, the direction of the band changes so that the reflection of the band occurs. At higher confining pressure, the new-formed shear band does not intersect the imperfection, bringing extreme difficulties in prediction of the failure of rock structure, such as rock burst. The present results enhance the understanding of the shear failure processes and patterns of rock specimen in higher confining pressure and higher loading strain rate.
