The sliding chairs are important components that support the switch rail conversion in the railway turnout.Due to the harsh environmental erosion and the attack from the wheel vibration,the failure rate of the sliding...The sliding chairs are important components that support the switch rail conversion in the railway turnout.Due to the harsh environmental erosion and the attack from the wheel vibration,the failure rate of the sliding chairs accounts for up to 10%of the total failure number in turnout.However,there is little research carried out in the existing literature to diagnose the deterioration states of the sliding chairs.To fill out this gap,by utilizing the images containing the sliding chairs,we propose an improved You Only Look Once version 7(YOLOv7)to identify the state of the sliding chairs.Specifically,to meet the challenge brought by the small inter-class differences among the sliding chair states,we first integrate the Convolutional Block Attention Module(CBAM)into the YOLOv7 backbone to screen the information conducive to state identification.Then,an extra detector for a small object is customized into the YOLOv7 network in order to detect the small-scale sliding chairs in images.Meanwhile,we revise the localization loss in the objective function as the Efficient Intersection over Union(EIoU)to optimize the design of the aspect ratio,which helps the localization of the sliding chairs.Next,to address the issue caused by the varying scales of the sliding chairs,we employ K-means++to optimize the priori selection of the initial anchor boxes.Finally,based on the images collected from real-world turnouts,the proposed method is verified and the results show that our method outperforms the basic YOLOv7 in the state identification of the sliding chairs with 4%improvements in terms of both mean Average Precision@0.5(mAP@0.5)and F1-score.展开更多
Welded Turnout on Large-span Bridge(WTLB)is a complex multi-layer heterogeneous system and can significantly influence the service performance of High-Speed Railway(HSR).Understanding the coupling dynamic response of ...Welded Turnout on Large-span Bridge(WTLB)is a complex multi-layer heterogeneous system and can significantly influence the service performance of High-Speed Railway(HSR).Understanding the coupling dynamic response of the vehicle and WTLB is essential.Previous research did not consider the dynamic behavior of foundations,leading to an underestimation of the vehicle-turnout-foundation coupling dynamic response,particularly when turnouts were laid on large-span bridges.This study proposes a novel modeling method that includes the foundations,to overcome the previous shortcomings by applying a rigid-flexible coupling system.In this approach,the vehicle was modeled as a rigid body sub-model in a Multi-Body Software(MBS),while WTLB was modeled as a flexible bodies sub-model using Finite Element(FE)software.The modal information from the FE model was imported into the MBS software.The two sub-models were coupled by the wheel-rail contact in the MBS environment and then the Vehicle-turnout-bridge Rigid-flexible Coupling Dynamic(VRCD)calculation model was established and it was discovered that the calculation results showed good agreement with the field test data.Through the VRCD model,the safety of the structure,the stability of the vehicle and the comfort of passengers were investigated,as well as several important infrastructure factors.The results demonstrate that this novel method provides accurate calculations and highlights the complex and significant interactions in the vehicle-turnout-bridge system.展开更多
An 88-year-old man presented symptoms and signs of ascending cholangitis and died 20 days after the onset of illness. Postmortem examination revealed a mucinous tumor arising from the head of the pancreas, encasing ...An 88-year-old man presented symptoms and signs of ascending cholangitis and died 20 days after the onset of illness. Postmortem examination revealed a mucinous tumor arising from the head of the pancreas, encasing the common bile duct and invading the liver with multiple hepatic metastasis. The tumor showed a unique and uniform histological apperarance, consisting of signet-ring neoplastic cells floating in mucin pools. The rapid clinical course and widespread hepatic metastasis of this patient suggest that this pure, signet-ring variant of mucinous adenocarcinoma of the pancreas might have a poorer prognosis.展开更多
Objectives To compare the postoperative complications and survival of standard pancreatoduodenectomy （SPD） and extended pancreatoduodenectomy （EPD） in patients with resectable adenocarcinoma of the head of the pan...Objectives To compare the postoperative complications and survival of standard pancreatoduodenectomy （SPD） and extended pancreatoduodenectomy （EPD） in patients with resectable adenocarcinoma of the head of the pancreas. Methods Between January 1994 and December 2011, 165 patients with biopsy-proven adenocardnoma of the pancreatic head were treated in West China Hospital, among whom 93 underwent SPD and 72 had EPD. Complications and survival after the surgery were analyzed retrospectively. Results The median operation time of the EPD group was longer compared with the SPD group （375 minutes vs. 310 minutes, P〈O.O1）, the volume of blood transfusion was larger （700 mL vs. 400 mL, P〈0.05）, while the median hospital stay （13.5 days vs. 12 days, P = 0.79） and the total complication rates were comparable （34.7% vs. 32.4%, P=0.93）. The total recurrence rates of the SPD and EPD groups were not significantly different （52.7% vs. 43.1%, P=0,83）. No significant differences were found between the SPD and EPD groups in 1-year （81.7% vs. 86.1%）, 3-year （38.7% vs. 43.1%）, 5-year （16.7% vs. 19.4%）, and median survivals （19.8 months vs. 23.2 months, P= 0.52）. Conclusion The postoperative complications and survival donot differ significantly between SPD and EPD.展开更多
By building the finite element model, the track parameters, including the ultimate longitudinal resistance, the length of the intermediate straight line, and the gap between spacer blocks, were analyzed for their infl...By building the finite element model, the track parameters, including the ultimate longitudinal resistance, the length of the intermediate straight line, and the gap between spacer blocks, were analyzed for their influences on the longitudinal forces and displacements of the single turnout and turnout group, respectively. The results indicate that when the longitudinal resistance drops from 32 to 20 N/cm, the maximum additional longitudinal force of the turnout group increases by 19. 2%, and the maximum additional longitudinal displacement of the turnout group grows by 85.3% compared with 50.4% for the single turnout. When the length of intermediate straight line rises from 0 m to infinite, the maximum additional longitudinal force decreases by 38.8%, and the maximum additional longitudinal displacement by 80.3%.展开更多
For the longitudinally coupled baUastless turnout on Leida bridge on Wuhan-Guangzhou passenger dedicated line （PDL） in China, a turnout （cross over）-track slab-bridge deck-pier integrated finite element model was ...For the longitudinally coupled baUastless turnout on Leida bridge on Wuhan-Guangzhou passenger dedicated line （PDL） in China, a turnout （cross over）-track slab-bridge deck-pier integrated finite element model was established, in which two No. 18 jointless turnouts with movable frogs in form of crossover, longitudinally coupled ballastless track, bridges and piers were regarded as one system. Based on this model, the additional forces and displacement regularities of turnouts, track slab, bridges and piers under occasional loading were analyzed, and the effect of occasional loading position was researched. The results show that slab breaking is more influential on the longitudinal force and deformation of the whole system than rail breaking, that slab breaking on one line could deteriorate both the slab force on another line and the forces exerted on the piers and fastener components, and that a great slab force at the left end of the continuous bridge expansion joint should be particularly avoided in design.展开更多
Although cholecystokinin is localized within neuronal fibres of the pancreas, a physiological role for intrapancreatic cholecystokinin has not been identified. The strategy of this study was to elicit pure vagal stimu...Although cholecystokinin is localized within neuronal fibres of the pancreas, a physiological role for intrapancreatic cholecystokinin has not been identified. The strategy of this study was to elicit pure vagal stimulation electrically, and to use specific receptor antagonists to identify the mediators of exocrine pancreatic secretion. We conclude that vagal stimulation of the rat pancreas involves ganglionic neurotransmission and release of acetylcholine and cholecystokinin from intrapancreatic, postganglionic fibres. To our knowledge, this is the first study to demonstrate a physiological role for intrapancreatic cholecystokinin.展开更多
Objective To analyze the clinical and ultrasonographic imaging features of intraductal papillary mutinous neoplasm （1PMN） of the pancreas. Methods Twelve patients with IPMN underwent surgery between May 2005 and De...Objective To analyze the clinical and ultrasonographic imaging features of intraductal papillary mutinous neoplasm （1PMN） of the pancreas. Methods Twelve patients with IPMN underwent surgery between May 2005 and December 2008, including 4 （33.3%） with adenoma and 8 （66.7%） with adenocarcinoma. IPMN was classified preoperatively into 3 types based on sonographic findings of different sites： main duct, branch duct, and combined type. All clinical presentations and ultrasonographic findings of those paticnts were reviewed and the correlation be- tween ultrasonographic hndings and histopathological results was analyzed. Results There were 9 men and 3 women with a mean age of 60.1±9.6 years （range, 32-73）. OF all the 12 patients with IPMN, 9 （75.0%） had experienced some symptoms of epigastric discomfort and/or pain as cell as backache; 7 cases were with medical history of acute pancreatitis, 5 cases with diabetes, 4 cases with elevated CA19-9, and 2 cases with steatorrhea. All lesions of IPMN have been revealed by transabdominal ul- trasonography. The mean diameters of the lesions were 1.4±0.8 cm （range, 0.5-2.0） and 6.3±6.0 cm （range, 2.0-20.0） in adenomas and adenocarcinomas, respectively. And the mean diameters of the main duct in adelnomas and adenocarcinomas were 1.0±0.8 cm and 1.6±1.0 cm, respectively. Among the 4 adnomas, 3 （75.0%） cases were classified as branch type based on sonographic findings, and 2 were demonstrated as mural nodules in which no color signals was detected. Among the 8 adenocarcinomas, 5 （62.5%） cases were classifled as main duct type, and 3 （37.5%） as combined type. In 7 of the 8 adcnocarcinomas, mural nodules were detected within the dilated ducts or cysts of the lesions in which color flow signals were detected. Conclusions Transabdominal ultrasonography can reveal the pancreatic cystic lesions of IPMN as well as dilated pancreatic： ducts. Some characteristics should be noticed as suggesting the possibility of malignancy： clinical symptoms of pancreatic insufficiency, large tumor size, and mural nodules with color Doppler flow signals. Transabdominal ultrasonography could be a useful tool to help diagnose and make appropriate management of IPMN.展开更多
Objective.To investigate the difference of rejection in single versus combined pancreas and kidney transplantation in rats. Methods.Allograft models including simultaneous pancreas and kidney(SPK)transplant and pancre...Objective.To investigate the difference of rejection in single versus combined pancreas and kidney transplantation in rats. Methods.Allograft models including simultaneous pancreas and kidney(SPK)transplant and pancreas or kidney transplant alone were established in SD-Wistar rats, rejections of pancreas and kidney in different models were compared morphologically and functionally. Results.Mean survival time(MST)of pancreas was significantly prolonged in SPK than in pancreas transplant alone(PTA)(115 days vs. 92 days, P<005). Incidence of interstitial pancreatic rejection at grade Ⅱ and grade Ⅲ was much obvious in PTA than in SPK(429% vs. 125% at grade Ⅱ and 286% vs 63% at grade Ⅲ , P<005). No significant difference was found in MST between SPK and kidney transplant alone(KTA). Administration of cyclosporine A prolonged the MST of pancreas and kidney, without altering the tendency stated above. Conclusions.In SPK, the function of pancreas is protected by kidney hence the severity of rejection is reduced, whereas the function of kidney is not protected by pancreas. It suggests that different organs differ in immunoallergization and immunoregulation, and immune response tend to attack organs with greater immunoactivity, those organs with minor one could be protected. Cyclosporine A is effective on prolonging the MST of pancreas and kidney.展开更多
Ectopic pancreas is a rare congenital malformation with pancreatic tissue in an aberrant loca tion and not contiguous with the main gland. Patients suffering from ectopic pancreas usually have lesions in the stomach o...Ectopic pancreas is a rare congenital malformation with pancreatic tissue in an aberrant loca tion and not contiguous with the main gland. Patients suffering from ectopic pancreas usually have lesions in the stomach or duodenum. Ectopic pancreatic tissue in the gallbladder is very rare, and only several cases have been reported. We report one case of a 33 year old man with ectopic pancreas presenting as repeatedly colic pain in the right upper quadrant of abdomen. He was first diagnosed as recurrent cholecys- titis accompanied by biliary pancreatitis, but surgical pathology proved he suffered from cholecystitis and ectopic pancreas in the gallbladder wall, and the laparoscopic cholecystectomy led to relief.展开更多
For meeting the clinic needs in simultaneous pancreas and kidney transplantation (SPK), we success-fully establish a syngeneic SPK transplatation model in Lewis rats. The results indicate that this model isfeasible wi...For meeting the clinic needs in simultaneous pancreas and kidney transplantation (SPK), we success-fully establish a syngeneic SPK transplatation model in Lewis rats. The results indicate that this model isfeasible with a 82. 6% successful rate of operation and a 69. 6% survival rate in the first postoperativeweek. In long-term survived rats, the blood supplies are well established, function of the grafts (pancreasand kidney) maintains normal. This model is suitable for theoretical reserach in SPK transplantation for itsreasonable physiology with pancreatic juice drained into intestine and reduced postoperative complications inurinary tract and carbohydrate metabolism.展开更多
The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wh...The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wheel-rail geometry relationship with the trace line method. The profile of the key rail sections was matched by cubic spline curve, and the shape interpolation was realized in non-controlling sections. The results show that the roll angles at each typical section increases gradually with the enlargement of track alignment irregularity. When the flange contact occurs, the roll angle increases dramatically. Proper track alignment irregularity towards the switch rail improves the structure irregularity of the turnout.展开更多
A space coupling vibration model of the system of wheel and lead curve rails of turnouts is presented, in which the vibration of the straight and curved rails are taken into account and the variations of the elastici...A space coupling vibration model of the system of wheel and lead curve rails of turnouts is presented, in which the vibration of the straight and curved rails are taken into account and the variations of the elasticity of roadbed with the length of switch ties are considered. It is used to investigate the dynamic characteristics of different configuration of lead curve, such as circular curve, cubic spiral and high order transition curves. Based on the numerical analysis, some advantageous configurations of lead curve are suggested.展开更多
For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the tur...For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge.展开更多
基金supported by the National Key R&D Program of China(2021YFF0501102)the National Natural Science Foundation of China(52372308,U2368202,U1934219,52202392,52022010,U22A2046,52172322,and 62271486).
文摘The sliding chairs are important components that support the switch rail conversion in the railway turnout.Due to the harsh environmental erosion and the attack from the wheel vibration,the failure rate of the sliding chairs accounts for up to 10%of the total failure number in turnout.However,there is little research carried out in the existing literature to diagnose the deterioration states of the sliding chairs.To fill out this gap,by utilizing the images containing the sliding chairs,we propose an improved You Only Look Once version 7(YOLOv7)to identify the state of the sliding chairs.Specifically,to meet the challenge brought by the small inter-class differences among the sliding chair states,we first integrate the Convolutional Block Attention Module(CBAM)into the YOLOv7 backbone to screen the information conducive to state identification.Then,an extra detector for a small object is customized into the YOLOv7 network in order to detect the small-scale sliding chairs in images.Meanwhile,we revise the localization loss in the objective function as the Efficient Intersection over Union(EIoU)to optimize the design of the aspect ratio,which helps the localization of the sliding chairs.Next,to address the issue caused by the varying scales of the sliding chairs,we employ K-means++to optimize the priori selection of the initial anchor boxes.Finally,based on the images collected from real-world turnouts,the proposed method is verified and the results show that our method outperforms the basic YOLOv7 in the state identification of the sliding chairs with 4%improvements in terms of both mean Average Precision@0.5(mAP@0.5)and F1-score.
基金supported by the National Natural Science Foundation of China(U23A20666)the China National Railway Group Corporation Science and Technology Research and Development Program(N2023G083).
文摘Welded Turnout on Large-span Bridge(WTLB)is a complex multi-layer heterogeneous system and can significantly influence the service performance of High-Speed Railway(HSR).Understanding the coupling dynamic response of the vehicle and WTLB is essential.Previous research did not consider the dynamic behavior of foundations,leading to an underestimation of the vehicle-turnout-foundation coupling dynamic response,particularly when turnouts were laid on large-span bridges.This study proposes a novel modeling method that includes the foundations,to overcome the previous shortcomings by applying a rigid-flexible coupling system.In this approach,the vehicle was modeled as a rigid body sub-model in a Multi-Body Software(MBS),while WTLB was modeled as a flexible bodies sub-model using Finite Element(FE)software.The modal information from the FE model was imported into the MBS software.The two sub-models were coupled by the wheel-rail contact in the MBS environment and then the Vehicle-turnout-bridge Rigid-flexible Coupling Dynamic(VRCD)calculation model was established and it was discovered that the calculation results showed good agreement with the field test data.Through the VRCD model,the safety of the structure,the stability of the vehicle and the comfort of passengers were investigated,as well as several important infrastructure factors.The results demonstrate that this novel method provides accurate calculations and highlights the complex and significant interactions in the vehicle-turnout-bridge system.
文摘An 88-year-old man presented symptoms and signs of ascending cholangitis and died 20 days after the onset of illness. Postmortem examination revealed a mucinous tumor arising from the head of the pancreas, encasing the common bile duct and invading the liver with multiple hepatic metastasis. The tumor showed a unique and uniform histological apperarance, consisting of signet-ring neoplastic cells floating in mucin pools. The rapid clinical course and widespread hepatic metastasis of this patient suggest that this pure, signet-ring variant of mucinous adenocarcinoma of the pancreas might have a poorer prognosis.
文摘Objectives To compare the postoperative complications and survival of standard pancreatoduodenectomy （SPD） and extended pancreatoduodenectomy （EPD） in patients with resectable adenocarcinoma of the head of the pancreas. Methods Between January 1994 and December 2011, 165 patients with biopsy-proven adenocardnoma of the pancreatic head were treated in West China Hospital, among whom 93 underwent SPD and 72 had EPD. Complications and survival after the surgery were analyzed retrospectively. Results The median operation time of the EPD group was longer compared with the SPD group （375 minutes vs. 310 minutes, P〈O.O1）, the volume of blood transfusion was larger （700 mL vs. 400 mL, P〈0.05）, while the median hospital stay （13.5 days vs. 12 days, P = 0.79） and the total complication rates were comparable （34.7% vs. 32.4%, P=0.93）. The total recurrence rates of the SPD and EPD groups were not significantly different （52.7% vs. 43.1%, P=0,83）. No significant differences were found between the SPD and EPD groups in 1-year （81.7% vs. 86.1%）, 3-year （38.7% vs. 43.1%）, 5-year （16.7% vs. 19.4%）, and median survivals （19.8 months vs. 23.2 months, P= 0.52）. Conclusion The postoperative complications and survival donot differ significantly between SPD and EPD.
基金The Doctoral Fund of Ministry of Educa-tionof China (No. 20050613007)
文摘By building the finite element model, the track parameters, including the ultimate longitudinal resistance, the length of the intermediate straight line, and the gap between spacer blocks, were analyzed for their influences on the longitudinal forces and displacements of the single turnout and turnout group, respectively. The results indicate that when the longitudinal resistance drops from 32 to 20 N/cm, the maximum additional longitudinal force of the turnout group increases by 19. 2%, and the maximum additional longitudinal displacement of the turnout group grows by 85.3% compared with 50.4% for the single turnout. When the length of intermediate straight line rises from 0 m to infinite, the maximum additional longitudinal force decreases by 38.8%, and the maximum additional longitudinal displacement by 80.3%.
文摘For the longitudinally coupled baUastless turnout on Leida bridge on Wuhan-Guangzhou passenger dedicated line （PDL） in China, a turnout （cross over）-track slab-bridge deck-pier integrated finite element model was established, in which two No. 18 jointless turnouts with movable frogs in form of crossover, longitudinally coupled ballastless track, bridges and piers were regarded as one system. Based on this model, the additional forces and displacement regularities of turnouts, track slab, bridges and piers under occasional loading were analyzed, and the effect of occasional loading position was researched. The results show that slab breaking is more influential on the longitudinal force and deformation of the whole system than rail breaking, that slab breaking on one line could deteriorate both the slab force on another line and the forces exerted on the piers and fastener components, and that a great slab force at the left end of the continuous bridge expansion joint should be particularly avoided in design.
文摘Although cholecystokinin is localized within neuronal fibres of the pancreas, a physiological role for intrapancreatic cholecystokinin has not been identified. The strategy of this study was to elicit pure vagal stimulation electrically, and to use specific receptor antagonists to identify the mediators of exocrine pancreatic secretion. We conclude that vagal stimulation of the rat pancreas involves ganglionic neurotransmission and release of acetylcholine and cholecystokinin from intrapancreatic, postganglionic fibres. To our knowledge, this is the first study to demonstrate a physiological role for intrapancreatic cholecystokinin.
文摘Objective To analyze the clinical and ultrasonographic imaging features of intraductal papillary mutinous neoplasm （1PMN） of the pancreas. Methods Twelve patients with IPMN underwent surgery between May 2005 and December 2008, including 4 （33.3%） with adenoma and 8 （66.7%） with adenocarcinoma. IPMN was classified preoperatively into 3 types based on sonographic findings of different sites： main duct, branch duct, and combined type. All clinical presentations and ultrasonographic findings of those paticnts were reviewed and the correlation be- tween ultrasonographic hndings and histopathological results was analyzed. Results There were 9 men and 3 women with a mean age of 60.1±9.6 years （range, 32-73）. OF all the 12 patients with IPMN, 9 （75.0%） had experienced some symptoms of epigastric discomfort and/or pain as cell as backache; 7 cases were with medical history of acute pancreatitis, 5 cases with diabetes, 4 cases with elevated CA19-9, and 2 cases with steatorrhea. All lesions of IPMN have been revealed by transabdominal ul- trasonography. The mean diameters of the lesions were 1.4±0.8 cm （range, 0.5-2.0） and 6.3±6.0 cm （range, 2.0-20.0） in adenomas and adenocarcinomas, respectively. And the mean diameters of the main duct in adelnomas and adenocarcinomas were 1.0±0.8 cm and 1.6±1.0 cm, respectively. Among the 4 adnomas, 3 （75.0%） cases were classified as branch type based on sonographic findings, and 2 were demonstrated as mural nodules in which no color signals was detected. Among the 8 adenocarcinomas, 5 （62.5%） cases were classifled as main duct type, and 3 （37.5%） as combined type. In 7 of the 8 adcnocarcinomas, mural nodules were detected within the dilated ducts or cysts of the lesions in which color flow signals were detected. Conclusions Transabdominal ultrasonography can reveal the pancreatic cystic lesions of IPMN as well as dilated pancreatic： ducts. Some characteristics should be noticed as suggesting the possibility of malignancy： clinical symptoms of pancreatic insufficiency, large tumor size, and mural nodules with color Doppler flow signals. Transabdominal ultrasonography could be a useful tool to help diagnose and make appropriate management of IPMN.
文摘Objective.To investigate the difference of rejection in single versus combined pancreas and kidney transplantation in rats. Methods.Allograft models including simultaneous pancreas and kidney(SPK)transplant and pancreas or kidney transplant alone were established in SD-Wistar rats, rejections of pancreas and kidney in different models were compared morphologically and functionally. Results.Mean survival time(MST)of pancreas was significantly prolonged in SPK than in pancreas transplant alone(PTA)(115 days vs. 92 days, P<005). Incidence of interstitial pancreatic rejection at grade Ⅱ and grade Ⅲ was much obvious in PTA than in SPK(429% vs. 125% at grade Ⅱ and 286% vs 63% at grade Ⅲ , P<005). No significant difference was found in MST between SPK and kidney transplant alone(KTA). Administration of cyclosporine A prolonged the MST of pancreas and kidney, without altering the tendency stated above. Conclusions.In SPK, the function of pancreas is protected by kidney hence the severity of rejection is reduced, whereas the function of kidney is not protected by pancreas. It suggests that different organs differ in immunoallergization and immunoregulation, and immune response tend to attack organs with greater immunoactivity, those organs with minor one could be protected. Cyclosporine A is effective on prolonging the MST of pancreas and kidney.
文摘Ectopic pancreas is a rare congenital malformation with pancreatic tissue in an aberrant loca tion and not contiguous with the main gland. Patients suffering from ectopic pancreas usually have lesions in the stomach or duodenum. Ectopic pancreatic tissue in the gallbladder is very rare, and only several cases have been reported. We report one case of a 33 year old man with ectopic pancreas presenting as repeatedly colic pain in the right upper quadrant of abdomen. He was first diagnosed as recurrent cholecys- titis accompanied by biliary pancreatitis, but surgical pathology proved he suffered from cholecystitis and ectopic pancreas in the gallbladder wall, and the laparoscopic cholecystectomy led to relief.
文摘For meeting the clinic needs in simultaneous pancreas and kidney transplantation (SPK), we success-fully establish a syngeneic SPK transplatation model in Lewis rats. The results indicate that this model isfeasible with a 82. 6% successful rate of operation and a 69. 6% survival rate in the first postoperativeweek. In long-term survived rats, the blood supplies are well established, function of the grafts (pancreasand kidney) maintains normal. This model is suitable for theoretical reserach in SPK transplantation for itsreasonable physiology with pancreatic juice drained into intestine and reduced postoperative complications inurinary tract and carbohydrate metabolism.
基金supported by the National Natural Science Foundation (No. 51008256)the Technological Research and Development Programsof the Ministry of Railways (No. 2010G006-B)
文摘The irregularity is a key factor affecting the wheel-rail contact geometry relationship. In this paper, we calculated the wheel-rail contact points at typical sections and obtained the longitudinal variation of the wheel-rail geometry relationship with the trace line method. The profile of the key rail sections was matched by cubic spline curve, and the shape interpolation was realized in non-controlling sections. The results show that the roll angles at each typical section increases gradually with the enlargement of track alignment irregularity. When the flange contact occurs, the roll angle increases dramatically. Proper track alignment irregularity towards the switch rail improves the structure irregularity of the turnout.
文摘A space coupling vibration model of the system of wheel and lead curve rails of turnouts is presented, in which the vibration of the straight and curved rails are taken into account and the variations of the elasticity of roadbed with the length of switch ties are considered. It is used to investigate the dynamic characteristics of different configuration of lead curve, such as circular curve, cubic spiral and high order transition curves. Based on the numerical analysis, some advantageous configurations of lead curve are suggested.
基金supported by the National Key R&D Program of China(2022YFB2602900)the 111 Project(B20040)the China Railway Science and Technology Research and Development Program Project(N2023T011-A(JB)).
文摘For high-speed railways,the smoothness of the railway line significantly affects the operational speed of trains.When the train passes through the turnout on a long-span bridge,the wheel-rail impacts caused by the turnout structure irregularities,and the instability arising from the bridge's flexural deformation lead to a strong coupling effect in the vehicle-turnout-bridge system.This significantly affects both ride comfort and operational safety.For addressing this issue,the present study considered a long-span continuous rigid-frame bridge as an example and established a train-turnout-bridge coupled dynamic model of high-speed railway.Utilizing a selfdeveloped dynamic simulation program,the study analysed the dynamic response characteristics when the train passes through the turnouts on the bridge.It also investigated the influence of different span-to-depth ratios of the bridge on the vehicle dynamic response when the train passes through the main line and branch line of turnouts and then proposed a span-to-depth ratio limit value for a long-span continuous rigid-frame bridge.The research findings suggest that the changes in the span-to-depth ratio have a relatively minor impact on the train’s operational performance but significantly affect the dynamic characteristics of the bridge structure.Based on the findings and a comprehensive assessment of safety indicators,it is advisable to establish a span-to-depth ratio limit of 1/4500 for a long-span continuous rigid-frame bridge.
