AIM:To evaluate the feasibility and safety of laparoscopic distal pancreatectomy(LDP) compared with open distal pancreatectomy(ODP).METHODS:Meta-analysis was performed using the databases,including PubMed,the Cochrane...AIM:To evaluate the feasibility and safety of laparoscopic distal pancreatectomy(LDP) compared with open distal pancreatectomy(ODP).METHODS:Meta-analysis was performed using the databases,including PubMed,the Cochrane Central Register of Controlled Trials,Web of Science and BIOSIS Previews.Articles should contain quantitative data of the comparison of LDP and ODP.Each article was reviewed by two authors.Indices of operative time,spleen-preserving rate,time to fluid intake,ratio of malignant tumors,postoperative hospital stay,incidence rate of pancreatic fistula and overall morbidity rate were analyzed.RESULTS:Nine articles with 1341 patients who underwent pancreatectomy met the inclusion criteria.LDP was performed in 501(37.4%) patients,while ODP was performed in 840(62.6%) patients.There were significant differences in the operative time,time to fluid intake,postoperative hospital stay and spleen-preserving rate between LDP and ODP.There was no difference between the two groups in pancreatic fistula rate [random effects model,risk ratio(RR) 0.996(0.663,1.494),P = 0.983,I2 = 28.4%] and overall morbidity rate [random effects model,RR 0.81(0.596,1.101),P = 0.178,I2 = 55.6%].CONCLUSION:LDP has the advantages of shorter hospital stay and operative time,more rapid recovery and higher spleen-preserving rate as compared with ODP.展开更多
A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culve...A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earth-quakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the cor-rugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground, which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.展开更多
Aiming to effectively solve the problem of deep mining with safety and high efficiency, according to geological conditions, production and stress analysis in roadway surrounding rock, experimental studies on roadway s...Aiming to effectively solve the problem of deep mining with safety and high efficiency, according to geological conditions, production and stress analysis in roadway surrounding rock, experimental studies on roadway supporting of workface 103 under three types of roof conditions with different supporting technologies and parameters were carried out based on the theory of supporting technology of gob-side entry. The results show the supporting of gob-side entry retaining is successful, and the deep surrounding rock is effectively controlled by field monitoring and drilling-hole photos. After stress in surrounding rock of roadways restores stable, the final roadway deformation of surrounding rock of haulage roadway and air-roadway are both about 300 mm; width of gob-side entry is 3.8-4.0 m and average height is 2.0-2.2 m; roadway section is above 8.0 m^2, which solves the problems of gob-side entry retaining support strength and safe mining; necessary conditions of mining safety in workface 103 are met.展开更多
To analyze the feasibility of application of composite material as the insulating material, it is necessary to have knowledge of some of its mechanical properties. An insulating material may suffer from the most diffe...To analyze the feasibility of application of composite material as the insulating material, it is necessary to have knowledge of some of its mechanical properties. An insulating material may suffer from the most different efforts, but the major applications suggest mechanical bending and compression tests because the insulation can be applied on roofs of homes, liners similar to, in the form of plates. Thus, the product is continually flexed. When the material is used on a floor, it suffers constant compressions over its use. For tests performed in this study, we used the ASTM D695-96 for compression, an example of literature. Using such a standard test, specimens were produced for compression test, with specimens made of cylindrical shapes, respecting the condition that the height of the specimen corresponds to twice the diameter of the base. Polyurethane castor without charge vermiculite and mass loads of 10%, 15% and 20% matrix: four specimens for each type of material were produced. The composites were tested in a universal testing machine at a speed of 2 mm/s. The results are average values of four test samples, and initially show the behavior of castor oil polyurethane during the compression test, which is detailed in the stress versus strain curve. The achieved results are promising, and detailed in this paper.展开更多
To solve the problems of abnormal larger, abnormal lower or even negative of target yield and fertilizing amount recommended by part of non-typical fertilizer effect equations using agricultural experiments and statis...To solve the problems of abnormal larger, abnormal lower or even negative of target yield and fertilizing amount recommended by part of non-typical fertilizer effect equations using agricultural experiments and statistical analysis software,Yangzhou analyzer(2.2), regression analysis of Excel, which objected to local actual production, the study adopted the principle and method of basic knowledge and the frequency of using probability theory, and carried out statistical analysis on the rape field fertilizer experiment data by frequency analysis method, the rape yield after optimizing fertilizing amount was 1 732.4 kg/hm^2, the ranges of N, P and K optimal combinations were: N=210.36-149.64 kg/hm^2,P2O5=81.89-58.11 kg/hm^2, K2O=81.89-58.11 kg/hm^2,which was consistent with local actual production. This study was based on frequency analysis, using weighted average method to determine the production combinations of different yield objectives, hereinto, the combinations with high yield, high frequency of occurrence(dependable crop) and fertilizer-saving were viewed as the optimizing production measures, and they had the merits of increasing fertilization decision-making information, reducing or avoiding the risk of small probability event. The results of this study can solve the problem of abnormal values fertilizing amount and target yield recommended by non-typical fertilizer effect function, which did not accord with local actual production, caused by Yangzhou analyzer(2.2), regression analysis of Excel, and DPS statistical analysis software. For the fertilizer effect function equation established by regression analysis which did not reach significance level using variance analysis, whether the method can be adapted to for carrying out fertilization decision-making, recommending optimization combinations of N, P and K fertilizers and yield under optimized fertilizing amount should be further researched in future working practice.展开更多
Soft rock control is a big challenge in underground engineering.As for this problem,a high-strength support technique of confined concrete(CC)arches is proposed and studied in this paper.Based on full-scale mechanical...Soft rock control is a big challenge in underground engineering.As for this problem,a high-strength support technique of confined concrete(CC)arches is proposed and studied in this paper.Based on full-scale mechanical test system of arch,research is made on the failure mechanism and mechanical properties of CC arch.Then,a mechanical calculation model of circular section is established for the arches with arbitrary section and unequal rigidity;a calculation formula is deduced for the internal force of the arch;an analysis is made on the influence of different factors on the internal force of the arch;and a calculation formula is got for the bearing capacity of CC arch through the strength criterion of bearing capacity.With numerical calculation and laboratory experiment,the ultimate bearing capacity and internal force distribution is analyzed for CC arches.The research results show that:1)CC arch is 2.31 times higher in strength than the U-shaped steel arch and has better stability;2)The key damage position of the arch is the two sides;3)Theoretical analysis,numerical calculation and laboratory experiment have good consistency in the internal force distribution,bearing capacity,and deformation and failure modes of the arch.All of that verifies the correctness of the theoretical calculation.Based on the above results,a field experiment is carried out in Liangjia Mine.Compared with the U-shaped steel arch support,CC arch support is more effective in surrounding rock deformation control.The research results can provide a basis for the design of CC arch support in underground engineering.展开更多
In order to compensate for limitations of microscopic study on loess triaxial tests, taking the loess in Longxi area as an example, the authors established the loess triaxial test model by using PFC3D software and sim...In order to compensate for limitations of microscopic study on loess triaxial tests, taking the loess in Longxi area as an example, the authors established the loess triaxial test model by using PFC3D software and simulating tfiaxial shear test under the different confining pressures in 0 kPa, 50 kPa and 300 kPa. Compared with laboratory triaxial shear test, the numerical simulation test has a guiding role in loess mechanical strength analysis.展开更多
AIM: To characterize the efficacy of rifaximin in the management of hepatic encephalopathy (HE) as several randomized controlled studies have shown contradictory results on its effectiveness in comparison to other ora...AIM: To characterize the efficacy of rifaximin in the management of hepatic encephalopathy (HE) as several randomized controlled studies have shown contradictory results on its effectiveness in comparison to other oral agents. METHODS: We performed a systematic review and random effects meta-analysis of all eligible trials identifi ed through electronic and manual searches. Twelve randomized controlled trials met the inclusion criteria with a total of 565 patients. RESULTS: The clinical effectiveness of rifaximin was equivalent to disaccharides or other oral antibiotics[odds ratio (OR) 0.96; 95% CI: 0.94-4.08] but with a better safety profi le (OR 0.27; 95% CI: 0.12-0.59). At the completion of treatment protocols, patients receiving rifaximin showed lower serum ammonia levels [weighted mean difference (WMD) = -10.65; 95% CI: -23.4-2.1; P = 0.10], better mental status (WMD = -0.24; 95% CI: -0.57-0.08; P = 0.15) and less asterixis (WMD -0.1; 95% CI -0.26-0.07; P = 0.25) without reaching statistical signifi cance. On the other hand, other psychometric outcomes such as electroencephalographic response and grades of portosystemic encephalopathy were superior in patients treated with rifaximin in comparison to the control group (WMD = 0.21, 95% CI: -0.33-0.09, P = 0.0004; and WMD = -2.33, 95% CI: -2.68-1.98, P = 0.00001, respectively). Subgroup and sensitivity analysis did not show any signifi cant difference in the above fi ndings. CONCLUSION: Rifaximin appears to be at least as effective as other conventional oral agents for the treatment of HE with a better safety profi le.展开更多
To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge blo...To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge block within the double-slide face was established by using the finite difference software according to the actual slope project combined with indoor model test. The pre-stress loss rule of the anchorage cable and the distribution of axial force and the force-transferring mechanism of the anchorage cable were analyzed during simulation. Also, based on the displacement contour and the safety factor of the calculated results, the quantitative analysis for the reinforcement ef- fect of the rock slope with group pre-stressed anchorage cable was discovered. The results computed by the software conform with the data in the experiment, which can prove the effectiveness and correctness of parameter selection and model building. Keywords group anchorage reinforcement, rock slope, joint fissure, pre-stressed anchorage cable, stress characteristics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
Determining the optimal timing is the core of preventive maintenance. Highway agencies always face with the challenge of determining optimal timing for preventive maintenance, particularly in China where there are no ...Determining the optimal timing is the core of preventive maintenance. Highway agencies always face with the challenge of determining optimal timing for preventive maintenance, particularly in China where there are no condition indicators designed for determining adequate timing for applying preventive maintenance and little literature relating to the development of pavement performance. This work presented the indicators, including crack ratio (Rc), rutting depth (DR), international roughness index (IIR) and sideway force coefficient (CsF) to determine the adequate timing for preventive maintenance in China. The proper ranges of each indicator to apply to preventive maintenance were then recommended. They are 0.28%-1.4% for Rc, 10-15 mm for DR, 1.97-3.5 for lrR, 40--50 for CSF. Based on pavement condition survey data collected on the test roads in Hebei Province, China, on the application of slurry seal at different timings, the pavement performance was established and the adequate timings for applying slurry seal was studied. Based on benefit-cost analysis, it is suggested that the fourth year is the optimal timing for applying slurry seal based on the condition in China. A framework is established to determine the adequate timings of applying other preventive maintenance methods.展开更多
The qualitative relationship between hydrogen concentration and notch tensile strength has been investigated for 5Ni-16Cr-Mo steel with different strength.The notch tensile strength was determined by means of slow str...The qualitative relationship between hydrogen concentration and notch tensile strength has been investigated for 5Ni-16Cr-Mo steel with different strength.The notch tensile strength was determined by means of slow strain rate test(SSRT)on circumferentially notched round bar specimens with the notch root radius of 0.15 mm after hydrogen charging.Meanwhile,the hydrogen diffusion behaviors of various strength steel were studied by thermal desorption spectroscopy(TDS)analysis.The SSRT results show that the T460 steel has higher susceptibility of hydrogen embrittlement in contrast with T520 steel.The activation energies and microstructure indicate that the dislocations and interfaces of martensitic laths are hydrogen traps in 5Ni-16Cr-Mo steel.By SSRT,the elastic limit of charged specimen loaded in air is higher than the flow stress without hydrogen charging before unloading,while the difference is defined as hydrogen-induced stress.The value of hydrogen-induced stress σ*increases linearly with hydrogen concentration:σ*=−0.622+2.015C0.The finite element analysis results of stress distributions near the notch tip have shown that the maximum principal stress increases with the notch root radius decreasing.展开更多
The collapsibility of loess, which can be effectively eliminated by the dynamic compaction, does great harm to the safety of constructions. The effect of the dynamic compaction is evaluated through the contrast and an...The collapsibility of loess, which can be effectively eliminated by the dynamic compaction, does great harm to the safety of constructions. The effect of the dynamic compaction is evaluated through the contrast and analysis of the physical and mechanical properties of the collapsible loess before and after dynamic compacting. The compacting effect can be divided into three phases along the depth, and the most effective improved depth is from 3 to 8 m.展开更多
Objective: The efficacy of preoperative transarterial chemoembolization(TACE) for hepatectomy on hepatocelluar carcinoma(HCC) is still controversial. This study aims to evaluate the efficacy of preoperative TACE on re...Objective: The efficacy of preoperative transarterial chemoembolization(TACE) for hepatectomy on hepatocelluar carcinoma(HCC) is still controversial. This study aims to evaluate the efficacy of preoperative TACE on resectable HCC. Methods: Pubmed, SCI, Medline, EMBASE, Cochrane Datebase, CNKI were searched. The articles that focused on preoperative TACE for resectable HCC, published from 1990 to 2012, were collected by computerized search of literatures and manual search of bibliographies. The relevant clinical trials' data were reviewed by meta-analysis using the random effects model or fixed effect model by heterogeneity. The outcomes were expressed as odds ratio(OR) with 95% confidence intervals(CIs). Results: A total of 1347 patients were included in these 7 studies, the cases were divided into the preoperative TACE group and the non-preoperative TACE group, and there was no difference between the two groups in the 3-year disease-free survival rate, with an odds ratio of 1.14(95% CI = 0.90–1.45, P = 0.27); the 5-year disease-free survival rate in the preoperative TACE group was better than that in the non-TACE group with an odds ratio of 1.35(95% CI = 1.07–1.74, P = 0.02); the 5-year overall survival rate in the preoperative TACE group was higher than that in the non-TACE group with an odds ratio of 0.59(95% CI = 0.46–0.77, P < 0.0001). Conclusion: The present data suggests that preoperative TACE has no different in improving the 3-year disease-free survival rate with non-TACE group for resectable HCC, while it can improve the 5-year disease-free survival rate and the 5-year overall survival rate. More randomized controlled trials using large sample size are needed to provide sufficient evidence to confirm current conclusion.展开更多
基金Supported by The key project grant from the Science and Technology Department of Zhejiang Province,No.2011C13036-2
文摘AIM:To evaluate the feasibility and safety of laparoscopic distal pancreatectomy(LDP) compared with open distal pancreatectomy(ODP).METHODS:Meta-analysis was performed using the databases,including PubMed,the Cochrane Central Register of Controlled Trials,Web of Science and BIOSIS Previews.Articles should contain quantitative data of the comparison of LDP and ODP.Each article was reviewed by two authors.Indices of operative time,spleen-preserving rate,time to fluid intake,ratio of malignant tumors,postoperative hospital stay,incidence rate of pancreatic fistula and overall morbidity rate were analyzed.RESULTS:Nine articles with 1341 patients who underwent pancreatectomy met the inclusion criteria.LDP was performed in 501(37.4%) patients,while ODP was performed in 840(62.6%) patients.There were significant differences in the operative time,time to fluid intake,postoperative hospital stay and spleen-preserving rate between LDP and ODP.There was no difference between the two groups in pancreatic fistula rate [random effects model,risk ratio(RR) 0.996(0.663,1.494),P = 0.983,I2 = 28.4%] and overall morbidity rate [random effects model,RR 0.81(0.596,1.101),P = 0.178,I2 = 55.6%].CONCLUSION:LDP has the advantages of shorter hospital stay and operative time,more rapid recovery and higher spleen-preserving rate as compared with ODP.
文摘A series of scaled-model shaking table tests and its simulation analyses using dynamic finite element method were performed to clarify the dynamic behaviors and the seismic stability of embedded corrugated steel culverts due to strong earth-quakes like the 1995 Hyogoken-nanbu earthquake. The dynamic strains of the embedded culvert models and the seismic soil pressure acting on the models due to sinusoidal and random strong motions were investigated. This study verified that the cor-rugated culvert model was subjected to dynamic horizontal forces (lateral seismic soil pressure) from the surrounding ground, which caused the large bending strains on the structure; and that the structures do not exceed the allowable plastic deformation and do not collapse completely during strong earthquake like Hyogoken-nanbu earthquake. The results obtained are useful for design and construction of embedded long span corrugated steel culverts in seismic regions.
文摘Aiming to effectively solve the problem of deep mining with safety and high efficiency, according to geological conditions, production and stress analysis in roadway surrounding rock, experimental studies on roadway supporting of workface 103 under three types of roof conditions with different supporting technologies and parameters were carried out based on the theory of supporting technology of gob-side entry. The results show the supporting of gob-side entry retaining is successful, and the deep surrounding rock is effectively controlled by field monitoring and drilling-hole photos. After stress in surrounding rock of roadways restores stable, the final roadway deformation of surrounding rock of haulage roadway and air-roadway are both about 300 mm; width of gob-side entry is 3.8-4.0 m and average height is 2.0-2.2 m; roadway section is above 8.0 m^2, which solves the problems of gob-side entry retaining support strength and safe mining; necessary conditions of mining safety in workface 103 are met.
文摘To analyze the feasibility of application of composite material as the insulating material, it is necessary to have knowledge of some of its mechanical properties. An insulating material may suffer from the most different efforts, but the major applications suggest mechanical bending and compression tests because the insulation can be applied on roofs of homes, liners similar to, in the form of plates. Thus, the product is continually flexed. When the material is used on a floor, it suffers constant compressions over its use. For tests performed in this study, we used the ASTM D695-96 for compression, an example of literature. Using such a standard test, specimens were produced for compression test, with specimens made of cylindrical shapes, respecting the condition that the height of the specimen corresponds to twice the diameter of the base. Polyurethane castor without charge vermiculite and mass loads of 10%, 15% and 20% matrix: four specimens for each type of material were produced. The composites were tested in a universal testing machine at a speed of 2 mm/s. The results are average values of four test samples, and initially show the behavior of castor oil polyurethane during the compression test, which is detailed in the stress versus strain curve. The achieved results are promising, and detailed in this paper.
基金Supported by Fiscal Subsidy Project Fund of National Soil Testing and Formulated Fertilization(Yun Cai Nong[2009]2045)~~
文摘To solve the problems of abnormal larger, abnormal lower or even negative of target yield and fertilizing amount recommended by part of non-typical fertilizer effect equations using agricultural experiments and statistical analysis software,Yangzhou analyzer(2.2), regression analysis of Excel, which objected to local actual production, the study adopted the principle and method of basic knowledge and the frequency of using probability theory, and carried out statistical analysis on the rape field fertilizer experiment data by frequency analysis method, the rape yield after optimizing fertilizing amount was 1 732.4 kg/hm^2, the ranges of N, P and K optimal combinations were: N=210.36-149.64 kg/hm^2,P2O5=81.89-58.11 kg/hm^2, K2O=81.89-58.11 kg/hm^2,which was consistent with local actual production. This study was based on frequency analysis, using weighted average method to determine the production combinations of different yield objectives, hereinto, the combinations with high yield, high frequency of occurrence(dependable crop) and fertilizer-saving were viewed as the optimizing production measures, and they had the merits of increasing fertilization decision-making information, reducing or avoiding the risk of small probability event. The results of this study can solve the problem of abnormal values fertilizing amount and target yield recommended by non-typical fertilizer effect function, which did not accord with local actual production, caused by Yangzhou analyzer(2.2), regression analysis of Excel, and DPS statistical analysis software. For the fertilizer effect function equation established by regression analysis which did not reach significance level using variance analysis, whether the method can be adapted to for carrying out fertilization decision-making, recommending optimization combinations of N, P and K fertilizers and yield under optimized fertilizing amount should be further researched in future working practice.
基金Projects(51674154,51704125,51874188) supported by the National Natural Science Foundation of ChinaProjects(2017T100116,2017T100491,2016M590150,2016M602144) supported by the China Postdoctoral Science Foundation+2 种基金Projects(2017GGX30101,2018GGX109001,ZR2017QEE013) supported by the Natural Science Foundation of Shandong Province,ChinaProject(SKLCRSM18KF012) supported by the State Key Laboratory of Coal Resources and Safe Mining,ChinaProject(2018WLJH76) supported by the Young Scholars Program of Shandong University,China
文摘Soft rock control is a big challenge in underground engineering.As for this problem,a high-strength support technique of confined concrete(CC)arches is proposed and studied in this paper.Based on full-scale mechanical test system of arch,research is made on the failure mechanism and mechanical properties of CC arch.Then,a mechanical calculation model of circular section is established for the arches with arbitrary section and unequal rigidity;a calculation formula is deduced for the internal force of the arch;an analysis is made on the influence of different factors on the internal force of the arch;and a calculation formula is got for the bearing capacity of CC arch through the strength criterion of bearing capacity.With numerical calculation and laboratory experiment,the ultimate bearing capacity and internal force distribution is analyzed for CC arches.The research results show that:1)CC arch is 2.31 times higher in strength than the U-shaped steel arch and has better stability;2)The key damage position of the arch is the two sides;3)Theoretical analysis,numerical calculation and laboratory experiment have good consistency in the internal force distribution,bearing capacity,and deformation and failure modes of the arch.All of that verifies the correctness of the theoretical calculation.Based on the above results,a field experiment is carried out in Liangjia Mine.Compared with the U-shaped steel arch support,CC arch support is more effective in surrounding rock deformation control.The research results can provide a basis for the design of CC arch support in underground engineering.
文摘In order to compensate for limitations of microscopic study on loess triaxial tests, taking the loess in Longxi area as an example, the authors established the loess triaxial test model by using PFC3D software and simulating tfiaxial shear test under the different confining pressures in 0 kPa, 50 kPa and 300 kPa. Compared with laboratory triaxial shear test, the numerical simulation test has a guiding role in loess mechanical strength analysis.
文摘AIM: To characterize the efficacy of rifaximin in the management of hepatic encephalopathy (HE) as several randomized controlled studies have shown contradictory results on its effectiveness in comparison to other oral agents. METHODS: We performed a systematic review and random effects meta-analysis of all eligible trials identifi ed through electronic and manual searches. Twelve randomized controlled trials met the inclusion criteria with a total of 565 patients. RESULTS: The clinical effectiveness of rifaximin was equivalent to disaccharides or other oral antibiotics[odds ratio (OR) 0.96; 95% CI: 0.94-4.08] but with a better safety profi le (OR 0.27; 95% CI: 0.12-0.59). At the completion of treatment protocols, patients receiving rifaximin showed lower serum ammonia levels [weighted mean difference (WMD) = -10.65; 95% CI: -23.4-2.1; P = 0.10], better mental status (WMD = -0.24; 95% CI: -0.57-0.08; P = 0.15) and less asterixis (WMD -0.1; 95% CI -0.26-0.07; P = 0.25) without reaching statistical signifi cance. On the other hand, other psychometric outcomes such as electroencephalographic response and grades of portosystemic encephalopathy were superior in patients treated with rifaximin in comparison to the control group (WMD = 0.21, 95% CI: -0.33-0.09, P = 0.0004; and WMD = -2.33, 95% CI: -2.68-1.98, P = 0.00001, respectively). Subgroup and sensitivity analysis did not show any signifi cant difference in the above fi ndings. CONCLUSION: Rifaximin appears to be at least as effective as other conventional oral agents for the treatment of HE with a better safety profi le.
基金Supported by the National Natural Science Foundation of China(50874085)
文摘To research the reinforcement effect of a rock slope with group anchorage cables and the stress characteristics of pre-stressed anchorage cables in the fractured surface, the rock slope calculated model of a wedge block within the double-slide face was established by using the finite difference software according to the actual slope project combined with indoor model test. The pre-stress loss rule of the anchorage cable and the distribution of axial force and the force-transferring mechanism of the anchorage cable were analyzed during simulation. Also, based on the displacement contour and the safety factor of the calculated results, the quantitative analysis for the reinforcement ef- fect of the rock slope with group pre-stressed anchorage cable was discovered. The results computed by the software conform with the data in the experiment, which can prove the effectiveness and correctness of parameter selection and model building. Keywords group anchorage reinforcement, rock slope, joint fissure, pre-stressed anchorage cable, stress characteristics
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Project(IRT1050) supported by Program for Changjiang Scholars and Innovative Research Team in University, ChinaProject (2009318000027) supported by Ministry of Transport of ChinaProject(CHD2011TD002) supported by the Special Fund for Basic Scientific Research of Central Colleges, Chang’an University, China
文摘Determining the optimal timing is the core of preventive maintenance. Highway agencies always face with the challenge of determining optimal timing for preventive maintenance, particularly in China where there are no condition indicators designed for determining adequate timing for applying preventive maintenance and little literature relating to the development of pavement performance. This work presented the indicators, including crack ratio (Rc), rutting depth (DR), international roughness index (IIR) and sideway force coefficient (CsF) to determine the adequate timing for preventive maintenance in China. The proper ranges of each indicator to apply to preventive maintenance were then recommended. They are 0.28%-1.4% for Rc, 10-15 mm for DR, 1.97-3.5 for lrR, 40--50 for CSF. Based on pavement condition survey data collected on the test roads in Hebei Province, China, on the application of slurry seal at different timings, the pavement performance was established and the adequate timings for applying slurry seal was studied. Based on benefit-cost analysis, it is suggested that the fourth year is the optimal timing for applying slurry seal based on the condition in China. A framework is established to determine the adequate timings of applying other preventive maintenance methods.
基金Project(3220024018)supported by the Fundamental Research Funds for the Luoyang Sunrui Special Equipment Co.,Ltd.,China。
文摘The qualitative relationship between hydrogen concentration and notch tensile strength has been investigated for 5Ni-16Cr-Mo steel with different strength.The notch tensile strength was determined by means of slow strain rate test(SSRT)on circumferentially notched round bar specimens with the notch root radius of 0.15 mm after hydrogen charging.Meanwhile,the hydrogen diffusion behaviors of various strength steel were studied by thermal desorption spectroscopy(TDS)analysis.The SSRT results show that the T460 steel has higher susceptibility of hydrogen embrittlement in contrast with T520 steel.The activation energies and microstructure indicate that the dislocations and interfaces of martensitic laths are hydrogen traps in 5Ni-16Cr-Mo steel.By SSRT,the elastic limit of charged specimen loaded in air is higher than the flow stress without hydrogen charging before unloading,while the difference is defined as hydrogen-induced stress.The value of hydrogen-induced stress σ*increases linearly with hydrogen concentration:σ*=−0.622+2.015C0.The finite element analysis results of stress distributions near the notch tip have shown that the maximum principal stress increases with the notch root radius decreasing.
基金Acknowledgement The authors of this paper thank the financial support from National Natural Science Foundation of China through project No.50478096.
文摘The collapsibility of loess, which can be effectively eliminated by the dynamic compaction, does great harm to the safety of constructions. The effect of the dynamic compaction is evaluated through the contrast and analysis of the physical and mechanical properties of the collapsible loess before and after dynamic compacting. The compacting effect can be divided into three phases along the depth, and the most effective improved depth is from 3 to 8 m.
文摘Objective: The efficacy of preoperative transarterial chemoembolization(TACE) for hepatectomy on hepatocelluar carcinoma(HCC) is still controversial. This study aims to evaluate the efficacy of preoperative TACE on resectable HCC. Methods: Pubmed, SCI, Medline, EMBASE, Cochrane Datebase, CNKI were searched. The articles that focused on preoperative TACE for resectable HCC, published from 1990 to 2012, were collected by computerized search of literatures and manual search of bibliographies. The relevant clinical trials' data were reviewed by meta-analysis using the random effects model or fixed effect model by heterogeneity. The outcomes were expressed as odds ratio(OR) with 95% confidence intervals(CIs). Results: A total of 1347 patients were included in these 7 studies, the cases were divided into the preoperative TACE group and the non-preoperative TACE group, and there was no difference between the two groups in the 3-year disease-free survival rate, with an odds ratio of 1.14(95% CI = 0.90–1.45, P = 0.27); the 5-year disease-free survival rate in the preoperative TACE group was better than that in the non-TACE group with an odds ratio of 1.35(95% CI = 1.07–1.74, P = 0.02); the 5-year overall survival rate in the preoperative TACE group was higher than that in the non-TACE group with an odds ratio of 0.59(95% CI = 0.46–0.77, P < 0.0001). Conclusion: The present data suggests that preoperative TACE has no different in improving the 3-year disease-free survival rate with non-TACE group for resectable HCC, while it can improve the 5-year disease-free survival rate and the 5-year overall survival rate. More randomized controlled trials using large sample size are needed to provide sufficient evidence to confirm current conclusion.