A spiral fluidity test model of superalloys with 10 mm in height and 3 mm in thickness was designed to evaluate the fluidity of two distinct Ni-based superalloys IN718 and IN939.The factors influencing fluidity are as...A spiral fluidity test model of superalloys with 10 mm in height and 3 mm in thickness was designed to evaluate the fluidity of two distinct Ni-based superalloys IN718 and IN939.The factors influencing fluidity are ascertained through comparative analysis utilizing methodologies such as JMat Pro,differential scanning calorimetry and high-temperature confocal laser scanning microscopy.The results show that under identical testing conditions,the fluidity of the IN939 superalloy surpasses that of the IN718 superalloy.When subjected to the same temperature,the melt viscosity and surface tension of IN939 superalloy are considerably reduced relative to those of IN718 superalloy,which is beneficial to improving the melt fluidity.Furthermore,the liquidus temperature and solidification range for the IN939 superalloy are both smaller compared with those of the IN718 superalloy.This condition proves advantageous in delaying dendrite coherency,thereby improving fluidity.展开更多
In order to analyze the initial cracking behavior of highway embankment in the regions of expansive soil, the changes in peaks of tensile stress and their location on top of the embankment for a typical highway embank...In order to analyze the initial cracking behavior of highway embankment in the regions of expansive soil, the changes in peaks of tensile stress and their location on top of the embankment for a typical highway embankment section were simulated by ABAQUS. The simulation results indicate that the matric suction was a concave distribution on top of the expansive soil foundation and that it induced differential deformation of foundation and embankment. The peaks of tensile stress on top of the embankment are not located at a fixed site, but gradually move towards the shoulder following the evaporation duration. When the evaporation intensity is larger, the peak of tensile stress on top of embankment increases at a faster rate following the evaporation duration,and its location is closer to the shoulder. The thicker expansive soil layer helps the peaks of tensile stress to reach the critical tensile stress quickly, but the embankment cannot crack when the expansive soil layer is no more than 1.5m after 30d soil surface evaporation; the higher the embankment, the smaller the peak of tensile stress occurring on top of the highway embankment, and its location will be further away from the shoulder. Therefore, a higher embankment constructed on a thinner expansive soil layer can reduce the crack generation within the highway embankment.展开更多
AIM: To evaluate the efficacy of transjugular intrahepatic portosystemic shunts (TIPSs) after liver transplantation (LT). METHODS: Between November 1996 and December 2005, 10 patients with severe recurrent hepat...AIM: To evaluate the efficacy of transjugular intrahepatic portosystemic shunts (TIPSs) after liver transplantation (LT). METHODS: Between November 1996 and December 2005, 10 patients with severe recurrent hepatitis C virus infection (n = 4), ductopenic rejection (n = 5) or portal vein thrombosis (n = 1) were included in this analysis. Eleven TIPSs (one patient underwent two TIPS procedures) were placed for management of therapy-refractory ascites (n = 7), hydrothorax (n = 2) or bleeding from colonic varices (n = 1). The median time interval between LT and TIPS placement was 15 (4-158) mo. RESULTS: TIPS placement was successful in all patients. The mean portosystemic pressure gradient was reduced from 12.5 to 8.7 mmHg. Complete and partial remission could be achieved in 43% and 29% of patients with ascites. Both patients with hydrothorax did not respond to TIPS. No recurrent bleeding was seen in the patient with colonic varices. Nine of 10 patients died during the study period. Only one of two patients, who underwent retransplantation after the TIPS procedure, survived. The median survival period after TIPS placement was 3.3 (range 0.4-20) too. The majority of patients died from sepsis with multiorgan failure. CONCLUSION: Indications for TIPS and technical performance in LT patients correspond to those in non-transplanted patients. At least partial control of therapy-refractory ascites and variceal bleeding could be achieved in most patients. Nevertheless, survival rates were disappointing, most probably because of the advanced stages of liver disease at the time of TIPS placement and the high risk of sepsis as a consequence of immunosuppression.展开更多
Background Obstructive sleep apnea (OSA) is the most common cause of resistant hypertension, which has been proposed to result from activation of the renin-angiotensin-aldosterone system (RAAS). We meta-analyzed t...Background Obstructive sleep apnea (OSA) is the most common cause of resistant hypertension, which has been proposed to result from activation of the renin-angiotensin-aldosterone system (RAAS). We meta-analyzed the effects of OSA on plasma levels of RAAS components. Methods Full-text studies published on MEDL1NE and EMBASE analyzing fasting plasma levels of at least one RAAS component in adults with OSA with or without hypertension. OSA was diagnosed as an apnea-hypopnea index or respiratory disturbance index 〉 5. Study quality was evaluated using the Newcastle-Ottawa Scale, and heterogeneity was assessed using the 12 statistic. Results from individual studies were synthesized using inverse variance and pooled using a random-effects model. Subgroup analysis, sensitivity analysis, and meta-regression were performed, and risk of publication bias was assessed. Results The meta-analysis included 13 studies, of which 10 reported results on renin (n = 470 cases and controls), 7 on angiotensin II (AnglI, n = 384), and 9 on aldosterone (n = 439). AnglI levels were significantly higher in OSA than in controls [mean differences = 3.39 ng/L, 95% CI: 2.00-4.79, P 〈 0.00001], while aldosterone levels were significantly higher in OSA with hypertension than OSA but not with hypertension (mean differences = 1.32 ng/dL, 95% CI: 0.58-2.07, P = 0.0005). Meta-analysis of all studies suggested no significant differences in aldosterone between OSA and controls, but a significant pooled mean difference of 1.35 ng/mL (95% CI: 0.88-1.82, P 〈 0.00001) emerged after excluding one small-sample study. No significant risk of publication bias was detected among all included studies. Conelusions OSA is associated with higher AnglI and aldosterone levels, espe- cially in hypertensive patients. OSA may cause hypertension, at least in part, by stimulating RAAS activity.展开更多
Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively....Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid circulation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid velocity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables.展开更多
Objective Radiation-induced lung injury (RILl) is the most common, dose-limiting complication in thoracic malignancy radiotherapy. Considering its negative impact on patients and restrictions to efficacy, the mechan...Objective Radiation-induced lung injury (RILl) is the most common, dose-limiting complication in thoracic malignancy radiotherapy. Considering its negative impact on patients and restrictions to efficacy, the mechanism of RILl was studied. Methods Wistar rats were locally irradiated with a single dose of 0, 16, and 20 Gy to the right half of the lung to establish a lung injury model. Two and six months after irradiation, the right half of the rat lung tissue was removed, and the concentrations of TGF-[31, angiotensin II, and aldosterone were determined via enzyme-linked immunosorbent assay. Results Statistical differences were observed in the expression levels of angiotensin II and aldosterone between the non-irradiation and irradiation groups. Moreover, the expression level of the angiotensin II-aldosterone system increased with increasing doses, and the difference was still observed as time progressed. Conclusions Angiotensin II-aldosterone system has an important pathophysiological function in the progression of RILI.展开更多
The effect of strain rate on tensile properties of cotton yarns is analyzed using the standard linear solid model. The tensile curve, breaking strength and work of rupture of the yarns under different strain rate are ...The effect of strain rate on tensile properties of cotton yarns is analyzed using the standard linear solid model. The tensile curve, breaking strength and work of rupture of the yarns under different strain rate are calculated. A good correlation exists between the experiment results and theoretical anticipations.展开更多
The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured clays.Viscosity coupled with destructuration is analysed based on experimental observations.A strain-rate bas...The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured clays.Viscosity coupled with destructuration is analysed based on experimental observations.A strain-rate based model is developed to de-scribe the mechanical behaviour for both unstructured and structured clays under one-dimensional loading.The advantage of the proposed model lies in the determination of model parameters in a straightforward way,which leads to an easy use of the model for practical problems.Coupled with consolidation,the model is used to simulate oedometer tests at constant rate of strain and long-term creep oedometer tests on two structured clays.All comparisons between predicted and measured results demonstrate that the proposed model can reasonably describe the effect of destructuration on the time-dependent behaviour of soft structured clay under one-dimensional condition.Although the model is proposed for one-dimensional analysis,it can be a good base for developing a more general 3D model.展开更多
The main purpose of the paper is to display the relaxation oscillations, known as the bursting phenomena, for the coupled oscillators with periodic excitation with an order gap between the exciting frequency and the n...The main purpose of the paper is to display the relaxation oscillations, known as the bursting phenomena, for the coupled oscillators with periodic excitation with an order gap between the exciting frequency and the natural frequency. For the case when the exciting frequency is much smaller than the natural frequency, different types of bursting oscillations such as fold/fold, Hopf/Hopf bursting oscillations can be observed. By regarding the whole exciting term as a slow-varying parameter on the fact that the exciting term changes on a much smaller time scale, bifurcations sets of the generalized autonomous system is derived, which divide the parameter space into several regions associated with different types of dynamical behaviors. Two cases with typical bifurcation patterns are focused on as examples to explore the dynamical evolution with the variation of the amplitude of the external excitation. Bursting oscillations which alternate between quiescent states (QSs) and repetitive spiking states (SPs) can be obtained, the mechanism of which is presented by introducing the transformed phase portraits overlapping with the bifurcation diagrams of the generalized autonomous system. It is found that not only the forms of QSs and SPs, but also the bifurcations at the transition points between QSs and SPs, may influence the structures of bursting attractors. Furthermore, the amplitudes and the frequencies related to SPs may depend on the bifurcation patterns from the quiescent sates.展开更多
Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications,such as variceal bleeding,ascites or hepatic encephalopathy.As such,clinically significant portal hyp...Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications,such as variceal bleeding,ascites or hepatic encephalopathy.As such,clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis.At present,non-selective bblockers,vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia.In contrast,safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue.In recent years,several preclinical and clinical trials have focused on this latter component and other therapeutic avenues.In this review,we highlight novel data in this context and address potentially interesting therapeutic options for the future.展开更多
Objective: To evaluate the feasibility and therapeutic effect of treating sternoclavicular joint dislocation by K-wire and tension band wire fixation, and to improve the safety and stability of this technique.Methods...Objective: To evaluate the feasibility and therapeutic effect of treating sternoclavicular joint dislocation by K-wire and tension band wire fixation, and to improve the safety and stability of this technique.Methods: This study consisted of 9 cases, 6 males and 3 females with the mean age of 25 years (range, 9-62 years).The causes were traffic accident in 7 cases, falling in 1 case and fight in 1 case. The duration from injury to operation was 2 hours to 7 days. There were 5 left dislocations and 4right dislocations; 8 anterior dislocations and 1 posterior dislocation, including one combined with left scapular fracture and one with left olecranon fracture. Open reduction and internal fixation using K-wires and tension band wires were performed to treat dislocations.Results: All patients were followed up for 6 to 24months, 10 months on average. According to Rockwood's rating scale on postoperative sternoclavicular joint, 8 cases achieved excellent outcomes with an average score of 13.88,and the rest case achieved a good outcome with the score of 12. Anatomical reduction was obtained in all cases. There were no such postoperative complications as severe infection, injury to blood vessel and nerve, failure of fixation,etc. Patients were all satisfied with the anatomical reduction and functional recovery.Conclusions: The technique of K-wire and tension band wire fixation is safe, simple, effective, less invasive and has been successfully used in orthopedic surgery. It is effective in treating sternoclavicular joint dislocation though it has some disadvantages.展开更多
基金support from the National Natural Science Foundation of China(Nos.52031012,51904218)。
文摘A spiral fluidity test model of superalloys with 10 mm in height and 3 mm in thickness was designed to evaluate the fluidity of two distinct Ni-based superalloys IN718 and IN939.The factors influencing fluidity are ascertained through comparative analysis utilizing methodologies such as JMat Pro,differential scanning calorimetry and high-temperature confocal laser scanning microscopy.The results show that under identical testing conditions,the fluidity of the IN939 superalloy surpasses that of the IN718 superalloy.When subjected to the same temperature,the melt viscosity and surface tension of IN939 superalloy are considerably reduced relative to those of IN718 superalloy,which is beneficial to improving the melt fluidity.Furthermore,the liquidus temperature and solidification range for the IN939 superalloy are both smaller compared with those of the IN718 superalloy.This condition proves advantageous in delaying dendrite coherency,thereby improving fluidity.
基金The National Natural Science Foundation of China(No.51378121)
文摘In order to analyze the initial cracking behavior of highway embankment in the regions of expansive soil, the changes in peaks of tensile stress and their location on top of the embankment for a typical highway embankment section were simulated by ABAQUS. The simulation results indicate that the matric suction was a concave distribution on top of the expansive soil foundation and that it induced differential deformation of foundation and embankment. The peaks of tensile stress on top of the embankment are not located at a fixed site, but gradually move towards the shoulder following the evaporation duration. When the evaporation intensity is larger, the peak of tensile stress on top of embankment increases at a faster rate following the evaporation duration,and its location is closer to the shoulder. The thicker expansive soil layer helps the peaks of tensile stress to reach the critical tensile stress quickly, but the embankment cannot crack when the expansive soil layer is no more than 1.5m after 30d soil surface evaporation; the higher the embankment, the smaller the peak of tensile stress occurring on top of the highway embankment, and its location will be further away from the shoulder. Therefore, a higher embankment constructed on a thinner expansive soil layer can reduce the crack generation within the highway embankment.
基金Supported by "Verein zur Frderung der Forschung in Gastroenterologie und Hepatologie an der Medizinischen Universitt Innsbruck"
文摘AIM: To evaluate the efficacy of transjugular intrahepatic portosystemic shunts (TIPSs) after liver transplantation (LT). METHODS: Between November 1996 and December 2005, 10 patients with severe recurrent hepatitis C virus infection (n = 4), ductopenic rejection (n = 5) or portal vein thrombosis (n = 1) were included in this analysis. Eleven TIPSs (one patient underwent two TIPS procedures) were placed for management of therapy-refractory ascites (n = 7), hydrothorax (n = 2) or bleeding from colonic varices (n = 1). The median time interval between LT and TIPS placement was 15 (4-158) mo. RESULTS: TIPS placement was successful in all patients. The mean portosystemic pressure gradient was reduced from 12.5 to 8.7 mmHg. Complete and partial remission could be achieved in 43% and 29% of patients with ascites. Both patients with hydrothorax did not respond to TIPS. No recurrent bleeding was seen in the patient with colonic varices. Nine of 10 patients died during the study period. Only one of two patients, who underwent retransplantation after the TIPS procedure, survived. The median survival period after TIPS placement was 3.3 (range 0.4-20) too. The majority of patients died from sepsis with multiorgan failure. CONCLUSION: Indications for TIPS and technical performance in LT patients correspond to those in non-transplanted patients. At least partial control of therapy-refractory ascites and variceal bleeding could be achieved in most patients. Nevertheless, survival rates were disappointing, most probably because of the advanced stages of liver disease at the time of TIPS placement and the high risk of sepsis as a consequence of immunosuppression.
文摘Background Obstructive sleep apnea (OSA) is the most common cause of resistant hypertension, which has been proposed to result from activation of the renin-angiotensin-aldosterone system (RAAS). We meta-analyzed the effects of OSA on plasma levels of RAAS components. Methods Full-text studies published on MEDL1NE and EMBASE analyzing fasting plasma levels of at least one RAAS component in adults with OSA with or without hypertension. OSA was diagnosed as an apnea-hypopnea index or respiratory disturbance index 〉 5. Study quality was evaluated using the Newcastle-Ottawa Scale, and heterogeneity was assessed using the 12 statistic. Results from individual studies were synthesized using inverse variance and pooled using a random-effects model. Subgroup analysis, sensitivity analysis, and meta-regression were performed, and risk of publication bias was assessed. Results The meta-analysis included 13 studies, of which 10 reported results on renin (n = 470 cases and controls), 7 on angiotensin II (AnglI, n = 384), and 9 on aldosterone (n = 439). AnglI levels were significantly higher in OSA than in controls [mean differences = 3.39 ng/L, 95% CI: 2.00-4.79, P 〈 0.00001], while aldosterone levels were significantly higher in OSA with hypertension than OSA but not with hypertension (mean differences = 1.32 ng/dL, 95% CI: 0.58-2.07, P = 0.0005). Meta-analysis of all studies suggested no significant differences in aldosterone between OSA and controls, but a significant pooled mean difference of 1.35 ng/mL (95% CI: 0.88-1.82, P 〈 0.00001) emerged after excluding one small-sample study. No significant risk of publication bias was detected among all included studies. Conelusions OSA is associated with higher AnglI and aldosterone levels, espe- cially in hypertensive patients. OSA may cause hypertension, at least in part, by stimulating RAAS activity.
基金Supported by Korea Institute of Energy Technology Evaluation and Planning (KETEP)GTL Technology Development Consortium (Korean National Oil Corp., Korea Gas Corp., Daelim Industrial Co. and Hyundai Engineering Co.) under "Energy Efficiency & Resources Programs" of the Ministry of Knowledge Economy, Republic of Korea
文摘Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid circulation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid velocity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables.
基金supported by grants from the National Natural Science Foundation of China(No.30900384)Education Bureau Foundation of Liaoning Province,China (No.2009a723)
文摘Objective Radiation-induced lung injury (RILl) is the most common, dose-limiting complication in thoracic malignancy radiotherapy. Considering its negative impact on patients and restrictions to efficacy, the mechanism of RILl was studied. Methods Wistar rats were locally irradiated with a single dose of 0, 16, and 20 Gy to the right half of the lung to establish a lung injury model. Two and six months after irradiation, the right half of the rat lung tissue was removed, and the concentrations of TGF-[31, angiotensin II, and aldosterone were determined via enzyme-linked immunosorbent assay. Results Statistical differences were observed in the expression levels of angiotensin II and aldosterone between the non-irradiation and irradiation groups. Moreover, the expression level of the angiotensin II-aldosterone system increased with increasing doses, and the difference was still observed as time progressed. Conclusions Angiotensin II-aldosterone system has an important pathophysiological function in the progression of RILI.
文摘The effect of strain rate on tensile properties of cotton yarns is analyzed using the standard linear solid model. The tensile curve, breaking strength and work of rupture of the yarns under different strain rate are calculated. A good correlation exists between the experiment results and theoretical anticipations.
文摘The paper aims to investigate the destructuration effect on the time-dependent behaviour of soft structured clays.Viscosity coupled with destructuration is analysed based on experimental observations.A strain-rate based model is developed to de-scribe the mechanical behaviour for both unstructured and structured clays under one-dimensional loading.The advantage of the proposed model lies in the determination of model parameters in a straightforward way,which leads to an easy use of the model for practical problems.Coupled with consolidation,the model is used to simulate oedometer tests at constant rate of strain and long-term creep oedometer tests on two structured clays.All comparisons between predicted and measured results demonstrate that the proposed model can reasonably describe the effect of destructuration on the time-dependent behaviour of soft structured clay under one-dimensional condition.Although the model is proposed for one-dimensional analysis,it can be a good base for developing a more general 3D model.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11272135, 21276115, 11472115 & 11472116)the Scientific Research Innovation Foundation of Jiangsu Province (Grant No.1291480004)
文摘The main purpose of the paper is to display the relaxation oscillations, known as the bursting phenomena, for the coupled oscillators with periodic excitation with an order gap between the exciting frequency and the natural frequency. For the case when the exciting frequency is much smaller than the natural frequency, different types of bursting oscillations such as fold/fold, Hopf/Hopf bursting oscillations can be observed. By regarding the whole exciting term as a slow-varying parameter on the fact that the exciting term changes on a much smaller time scale, bifurcations sets of the generalized autonomous system is derived, which divide the parameter space into several regions associated with different types of dynamical behaviors. Two cases with typical bifurcation patterns are focused on as examples to explore the dynamical evolution with the variation of the amplitude of the external excitation. Bursting oscillations which alternate between quiescent states (QSs) and repetitive spiking states (SPs) can be obtained, the mechanism of which is presented by introducing the transformed phase portraits overlapping with the bifurcation diagrams of the generalized autonomous system. It is found that not only the forms of QSs and SPs, but also the bifurcations at the transition points between QSs and SPs, may influence the structures of bursting attractors. Furthermore, the amplitudes and the frequencies related to SPs may depend on the bifurcation patterns from the quiescent sates.
文摘Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications,such as variceal bleeding,ascites or hepatic encephalopathy.As such,clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis.At present,non-selective bblockers,vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia.In contrast,safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue.In recent years,several preclinical and clinical trials have focused on this latter component and other therapeutic avenues.In this review,we highlight novel data in this context and address potentially interesting therapeutic options for the future.
文摘Objective: To evaluate the feasibility and therapeutic effect of treating sternoclavicular joint dislocation by K-wire and tension band wire fixation, and to improve the safety and stability of this technique.Methods: This study consisted of 9 cases, 6 males and 3 females with the mean age of 25 years (range, 9-62 years).The causes were traffic accident in 7 cases, falling in 1 case and fight in 1 case. The duration from injury to operation was 2 hours to 7 days. There were 5 left dislocations and 4right dislocations; 8 anterior dislocations and 1 posterior dislocation, including one combined with left scapular fracture and one with left olecranon fracture. Open reduction and internal fixation using K-wires and tension band wires were performed to treat dislocations.Results: All patients were followed up for 6 to 24months, 10 months on average. According to Rockwood's rating scale on postoperative sternoclavicular joint, 8 cases achieved excellent outcomes with an average score of 13.88,and the rest case achieved a good outcome with the score of 12. Anatomical reduction was obtained in all cases. There were no such postoperative complications as severe infection, injury to blood vessel and nerve, failure of fixation,etc. Patients were all satisfied with the anatomical reduction and functional recovery.Conclusions: The technique of K-wire and tension band wire fixation is safe, simple, effective, less invasive and has been successfully used in orthopedic surgery. It is effective in treating sternoclavicular joint dislocation though it has some disadvantages.