In current research, a series of triaxial tests, which were employed to simulate three typical mining lay-outs (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using...In current research, a series of triaxial tests, which were employed to simulate three typical mining lay-outs (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using MTS815 Flex Test GT rock mechanics test system, and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruc-tion techniques. This work aimed at providing a detail description on the micro-structure and fracture-connectivity characteristics of rupture coal samples under different mining layouts. The results show that: (i) for protected coal seam mining layout, the coal specimens failure is in a compression-shear manner and oppositely, (ii) the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts. By investigating the connectivity features of the generated fractures in the direction of r1 under different mining layouts, it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.展开更多
BACKGROUND: There is controversy regarding whether saddle main pulmonary artery(MPA) embolism represents a high risk of deterioration in non-high-risk acute pulmonary embolism(PE) patients. This study aims to address ...BACKGROUND: There is controversy regarding whether saddle main pulmonary artery(MPA) embolism represents a high risk of deterioration in non-high-risk acute pulmonary embolism(PE) patients. This study aims to address this issue by conducting a propensity score matching(PSM) study.METHODS: A total of 727 non-high-risk acute PE patients were retrospectively evaluated. We evaluated the Bova score and risk stratification to examine the risk of deterioration. Deterioration defined as any adverse event within 30 days after admission. Computed tomographic pulmonary angiography was used to identify the embolism type. All patients were matched into four subgroups by PSM according to age, sex, Bova score, and risk stratification:(1) MPA and non-MPA embolism;(2) non-saddle MPA and non-MPA embolism;(3) saddle MPA and non-saddle MPA embolism;(4) saddle MPA and non-MPA embolism. Correlations were analyzed using Cox regression analysis, and deterioration risk was compared between subgroups using Kaplan-Meier analysis.RESULTS: Cox regression analysis revealed that MPA embolism was correlated with deterioration, regardless of whether saddle MPA embolism was included or excluded. Saddle MPA embolism was not correlated with deterioration, regardless of comparison with non-saddle MPA embolism or non-MPA embolism. Patients with MPA and non-saddle MPA embolism presented a high risk for deterioration(logrank test=5.23 and 4.70, P=0.022 and 0.030, respetively), while patients with saddle MPA embolism were not at a high risk of deterioration(log-rank test=1.20 and 3.17, P=0.729 and 0.077, respetively).CONCLUSIONS: Saddle MPA embolism is not indicative of a high risk of deterioration in nonhigh-risk acute PE patients.展开更多
基金financially supported by the Major State Fundamental Research Project of China(Nos.2011CB201201and2010CB226802)the National Natural Science Foundation of China(No.51204113)the Youth Science and Technology Fund of Sichuan Province(No.2012JQ0031)
文摘In current research, a series of triaxial tests, which were employed to simulate three typical mining lay-outs (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using MTS815 Flex Test GT rock mechanics test system, and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruc-tion techniques. This work aimed at providing a detail description on the micro-structure and fracture-connectivity characteristics of rupture coal samples under different mining layouts. The results show that: (i) for protected coal seam mining layout, the coal specimens failure is in a compression-shear manner and oppositely, (ii) the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts. By investigating the connectivity features of the generated fractures in the direction of r1 under different mining layouts, it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.
基金supported by the 345 Talent Project,Shengjing Hospital of China Medical University。
文摘BACKGROUND: There is controversy regarding whether saddle main pulmonary artery(MPA) embolism represents a high risk of deterioration in non-high-risk acute pulmonary embolism(PE) patients. This study aims to address this issue by conducting a propensity score matching(PSM) study.METHODS: A total of 727 non-high-risk acute PE patients were retrospectively evaluated. We evaluated the Bova score and risk stratification to examine the risk of deterioration. Deterioration defined as any adverse event within 30 days after admission. Computed tomographic pulmonary angiography was used to identify the embolism type. All patients were matched into four subgroups by PSM according to age, sex, Bova score, and risk stratification:(1) MPA and non-MPA embolism;(2) non-saddle MPA and non-MPA embolism;(3) saddle MPA and non-saddle MPA embolism;(4) saddle MPA and non-MPA embolism. Correlations were analyzed using Cox regression analysis, and deterioration risk was compared between subgroups using Kaplan-Meier analysis.RESULTS: Cox regression analysis revealed that MPA embolism was correlated with deterioration, regardless of whether saddle MPA embolism was included or excluded. Saddle MPA embolism was not correlated with deterioration, regardless of comparison with non-saddle MPA embolism or non-MPA embolism. Patients with MPA and non-saddle MPA embolism presented a high risk for deterioration(logrank test=5.23 and 4.70, P=0.022 and 0.030, respetively), while patients with saddle MPA embolism were not at a high risk of deterioration(log-rank test=1.20 and 3.17, P=0.729 and 0.077, respetively).CONCLUSIONS: Saddle MPA embolism is not indicative of a high risk of deterioration in nonhigh-risk acute PE patients.
