To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandston...To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandstone under dry and water-saturated conditions.Experimental results showed that high temperatures effectively weakened the tensile strength of sandstone specimens,and the P-wave velocity declined with increasing temperature.Overall,thermal damage of rock increased gradually with increasing temperature,but obvious negative damage appeared at the temperature of 100℃.The water-saturated sandstone specimens had lower indirect tensile strength than the dry ones,which indicated that water-rock interaction led to secondary damage in heat-treated rock.Under both dry and water-saturated conditions,the dynamic tensile strength of sandstone increased with the increase of strain rate.The water-saturated rock specimens showed stronger rate dependence than the dry ones,but the loading rate sensitivity of thermally treated rock decreased with increasing treatment temperature.With the help of scanning electron microscopy technology,the thermal fractures of rock,caused by extreme temperature,were analyzed.Hydro-physical mechanisms of sandstone under different loading rate conditions after heat treatment were further discussed.展开更多
Objective： Cardiac injuries are one of the most challenging injuries in the field of trauma surgery. Their management often requires immediate surgical intervention, excellent surgical technique and the ability to pr...Objective： Cardiac injuries are one of the most challenging injuries in the field of trauma surgery. Their management often requires immediate surgical intervention, excellent surgical technique and the ability to provide excellent postoperative critical care to patients. The aim of this study was to evaluate the outcome and survival rate of patients with penetrating cardiac injury in southern Iran, Shiraz. Methods： From January 2001 to June 2007, medical records of all patients suffering from penetrating cardiac injuries were reviewed and their outcomes were investigated. The inclusion criterion was the presence of a confirmed penetrating cardiac injury intraoperatively or by autopsy. Patients with blunt cardiac injuries were excluded from the study. Results： The study consisted of 37 patients, including 1 gunshot wound （2.7%）, 35 stab wounds （94.6%） and 1 （2.7%） shotgun wound. The overall survival rate was 76% （28 in 37） and that in stab wound patients was 80%. The collected data of 9 expired patients revealed 11% death on arrival, 67% hypotensive, and 22% normotensive considering physiologic presentation. Paired sample test showed sig- nificant correlation between mortality and electrocardio- graphic changes, amount of retained blood in pericardium, clinical stage and physiologic condition at presentation, as well as associated injury type （gunshot more than stab wound）. Conclusion： Our results show that injury mechanism and initial cardiac rhythm are significant predictors of out- comes in patients with penetrating cardiac injuries. Besides, gunshot injury and exsanguination are the most important predictive variables of mortality.展开更多
Objective：To compare the value of Glasgow coma scale （GCS） and cerebral state index （CSI）on predicting hospital discharge status of acute braininjured patients.Methods：In 60 brain-injured patients who did not re...Objective：To compare the value of Glasgow coma scale （GCS） and cerebral state index （CSI）on predicting hospital discharge status of acute braininjured patients.Methods：In 60 brain-injured patients who did not receive sedatives,GCS and CSI were measured daily during the first 10 days of hospitalization.The outcome of prognostic cut-off points was calculated by GCS and CSI using receiver operating characteristic （ROC） curve regarding the time of admission and third day of hospitalization.Sensitivity,specificity and other predictive values for both indices were calculated.Results：Of the 60 assessed patients,14 patients had mild,13 patients had moderate and 33 patients had severe injuries.During the course of the study,17 patients （28.3％） deteriorated in their situation and died.The mean GCS and CSI in patients who deceased during hospitalization was significantly lower than those who were discharged from the hospital.GCS＜4.5 and CSI＜64.5 at the time of admission was associated with higher mortality risk in traumatic brain injury patients and GCS was more sensitive than CSI to predict in-hospital death in these patients.For the first day of hospitalization,the area under ROC curve was 0.947 for GCS and 0.732 for CSI.Conclusion：GCS score at ICU admission is a good predictor of in-hospital mortality.GCS＜4.5 and CSI＜64.5 at the time of admission is associated with higher mortality risk in traumatic brain injury patients and GCS is more sensitive than CSI in predicting death in these patients.展开更多
基金Projects(41972283,41630642)supported by the National Natural Science Foundation of ChinaProject(51927808)supported by the National Key Scientific Instrument and Equipment Development,ChinaProject(CX2018B066)supported by the Hunan Provincial Innovation Foundation for Postgraduate,China。
文摘To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandstone under dry and water-saturated conditions.Experimental results showed that high temperatures effectively weakened the tensile strength of sandstone specimens,and the P-wave velocity declined with increasing temperature.Overall,thermal damage of rock increased gradually with increasing temperature,but obvious negative damage appeared at the temperature of 100℃.The water-saturated sandstone specimens had lower indirect tensile strength than the dry ones,which indicated that water-rock interaction led to secondary damage in heat-treated rock.Under both dry and water-saturated conditions,the dynamic tensile strength of sandstone increased with the increase of strain rate.The water-saturated rock specimens showed stronger rate dependence than the dry ones,but the loading rate sensitivity of thermally treated rock decreased with increasing treatment temperature.With the help of scanning electron microscopy technology,the thermal fractures of rock,caused by extreme temperature,were analyzed.Hydro-physical mechanisms of sandstone under different loading rate conditions after heat treatment were further discussed.
文摘Objective： Cardiac injuries are one of the most challenging injuries in the field of trauma surgery. Their management often requires immediate surgical intervention, excellent surgical technique and the ability to provide excellent postoperative critical care to patients. The aim of this study was to evaluate the outcome and survival rate of patients with penetrating cardiac injury in southern Iran, Shiraz. Methods： From January 2001 to June 2007, medical records of all patients suffering from penetrating cardiac injuries were reviewed and their outcomes were investigated. The inclusion criterion was the presence of a confirmed penetrating cardiac injury intraoperatively or by autopsy. Patients with blunt cardiac injuries were excluded from the study. Results： The study consisted of 37 patients, including 1 gunshot wound （2.7%）, 35 stab wounds （94.6%） and 1 （2.7%） shotgun wound. The overall survival rate was 76% （28 in 37） and that in stab wound patients was 80%. The collected data of 9 expired patients revealed 11% death on arrival, 67% hypotensive, and 22% normotensive considering physiologic presentation. Paired sample test showed sig- nificant correlation between mortality and electrocardio- graphic changes, amount of retained blood in pericardium, clinical stage and physiologic condition at presentation, as well as associated injury type （gunshot more than stab wound）. Conclusion： Our results show that injury mechanism and initial cardiac rhythm are significant predictors of out- comes in patients with penetrating cardiac injuries. Besides, gunshot injury and exsanguination are the most important predictive variables of mortality.
文摘Objective：To compare the value of Glasgow coma scale （GCS） and cerebral state index （CSI）on predicting hospital discharge status of acute braininjured patients.Methods：In 60 brain-injured patients who did not receive sedatives,GCS and CSI were measured daily during the first 10 days of hospitalization.The outcome of prognostic cut-off points was calculated by GCS and CSI using receiver operating characteristic （ROC） curve regarding the time of admission and third day of hospitalization.Sensitivity,specificity and other predictive values for both indices were calculated.Results：Of the 60 assessed patients,14 patients had mild,13 patients had moderate and 33 patients had severe injuries.During the course of the study,17 patients （28.3％） deteriorated in their situation and died.The mean GCS and CSI in patients who deceased during hospitalization was significantly lower than those who were discharged from the hospital.GCS＜4.5 and CSI＜64.5 at the time of admission was associated with higher mortality risk in traumatic brain injury patients and GCS was more sensitive than CSI to predict in-hospital death in these patients.For the first day of hospitalization,the area under ROC curve was 0.947 for GCS and 0.732 for CSI.Conclusion：GCS score at ICU admission is a good predictor of in-hospital mortality.GCS＜4.5 and CSI＜64.5 at the time of admission is associated with higher mortality risk in traumatic brain injury patients and GCS is more sensitive than CSI in predicting death in these patients.
