The hot deformation behavior of TC18 alloy at strain rates ranging from 1 × 10-4 to 1 x 10-2 s-1 and temperatures ranging from 25 to 800 ℃ was studied using a WDW-300 electronic universal testing machine. The re...The hot deformation behavior of TC18 alloy at strain rates ranging from 1 × 10-4 to 1 x 10-2 s-1 and temperatures ranging from 25 to 800 ℃ was studied using a WDW-300 electronic universal testing machine. The relationships between true flow stress decreases with stress and true strain show that the increase of temperature and increases as strain rate increases. The effect of strain rate on the flow stress becomes pronounced at higher temper- atures. At room temperature, the river pattern characteristic of brittle fracture and the dimple pattern typical of ductile fracture are found to exist in different regions of fracture surfaces of the samples. An improved constitutive rela- tionship is proposed to accurately describe the flow stress of TC18 by considering the effect of strain. And a micro- scopic model is also deduced which can link the physical mechanisms to the macroscopic experimental results. A good agreement is obtained between the predictions of the microscopic model and the results of the macroscopic experiment.展开更多
Theα+βdual phase titanium alloys are key structural materials in aviation and aero-space industries,and the complicated flow behavior of these titanium alloys during hot deformation requires to establish a constitut...Theα+βdual phase titanium alloys are key structural materials in aviation and aero-space industries,and the complicated flow behavior of these titanium alloys during hot deformation requires to establish a constitutive model incorporating physical mechanism for optimizing process-ing parameters and designing forming tools.This work aims to establish a constitutive model incor-porating physical mechanism for hot deformation of TC18 inα+βphase region.Firstly,the flow behavior and microstructure evolution for hot deformation of TC18 inα+βphase region are char-acterized.The TC18 shows significant strain hardening rate and negative strain hardening exponent around and after peak flow stress,respectively.After peak flow stress,Dynamic Recovery(DRV)mechanism dominates the evolution of a and b phases according to the results of substructure evo-lution.Then,the internal state variables method is applied to establish a constitutive model incor-porating physical mechanism for hot deformation of dual phase titanium alloys.The variation of dislocation density during the hot deformation of titanium alloys is modeled by considering the accumulation of dislocation due to the impediment to dislocation movement by substructure obsta-cles and the annihilation of dislocation due to the dynamic restoration effect.The interaction between dislocations,the subgrain boundaries and the grain/phase boundaries obstruct the disloca-tion movement in the a phase,and the first two obstructs the dislocation movement in the b phase during the hot deformation of TC18.The dislocation annihilation process in theαandβphases dur-ing the hot deformation of TC18 is dominated by DRV.Finally,the substructure evolution in the two phases based constitutive model for hot deformation of TC18 inα+βphase region is presented.This model is well applied to predict the flow stress and quantitively analyze the role of DRV effect in the evolution ofαandβphases during the hot deformation of TC18.展开更多
It is an undeniable fact that the success or the failure of any given society or community of human beings depends largely on who controls the affairs of that group.A leader without a clear vision and setting objectiv...It is an undeniable fact that the success or the failure of any given society or community of human beings depends largely on who controls the affairs of that group.A leader without a clear vision and setting objectives simply drags the group being led into turmoil,while a good leadership paves the way to upward movement of a group of human beings under such a leadership.Searching for a model of good leadership becomes then a serious need in any human society since success is desired by everybody.This study has therefore searched for a recommendable or model of good leadership in the light of Exodus 18:12-27 and African culture.The biblical text was studied as a narrative peace dealing with the change of leadership style by Moses,the ancient leader of the Israelites.He changed from the sole-actor style of leadership to a collaborative and democratic type due to the good advice given to him by Jethro,his father-in-law.This type,in which there was decentralisation of leadership authority,was found to be beneficial to all involved,because the work of the leader(Moses)was made lighter and the led got quicker services.African concepts of leadership were also studied,and it was found out that the African/Igbo democratic style is highly recommendable because it is caring;it has good“listening ears”and excludes dictatorship,without degenerating to the laissez-faire type of leadership.Of the various types of leadership styles examined,the democratic,collaborative type ranks first as recommendable.The Jesus-model of leadership as entailing love and service rather than exploitation,as well as the transparency model of leadership offered by St.Paul in the NT,present themselves as models of good leadership.A good leader serves the interest of the group under his/her charge and not his or her selfish and nepotistic interest.展开更多
Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng su-perlarge-scale porphyry-type molybd...Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng su-perlarge-scale porphyry-type molybdenum deposit were investigated. It was revealed that in thepre-metallogenic and early-metallogenic epehs, the ore-forming fluid was a residual fluid derived from magmatic water-wall rock interaction at middle to high temperatures (T = 250 -500℃) and lower W/R ratios (0. 1 > = W/R >0.001 ), while in the metallogenic and Post-metallogenic epochs, the ore-forming nuid was a residual fluid derived from meteoric water-wallrock interaction at midd1e to lower temperatures (T = 150 - 310℃ ) and relatively high W/Rratios (0. 5 >W/R≥0.1 ). The meteoric water played an important role in molybdenum min-eralization, and at the main metallogenic epoch the W/R ratio reached its maximum value.展开更多
In order to investigate the effects of interleukin-18 （IL-18） on airway inflammation and the Th1/Th2 cytokine balance in guinea pig asthmatic model as well as its possible mechanisms, the asthmatic model was establi...In order to investigate the effects of interleukin-18 （IL-18） on airway inflammation and the Th1/Th2 cytokine balance in guinea pig asthmatic model as well as its possible mechanisms, the asthmatic model was established by intraperitoneal injection of ovalbumin （OVA） and aerosol challenges into guinea pigs, and 30 treated animals were randomly divided into three groups of 10 animals in each groups, in which group A served as the asthmatic model, group B as the controls and group C as the group treated with IL-18. The counting and categorization of the inflammatory cells in bronchoalveolar lavage fluid （BALF） were performed by using light microscopy, and the contents of cytokines （ IFN-γ, IL- 2, IL-4 and IL-5） were assayed by means of the ELISA kit. The experimental results showed that the numbers of eosinophils （ESO） in BALF of group A, B and C were （97.70 ± 58.03） × 10^6/L, （11.68 × 9.95） × 10^6/L and （28.62 ± 10.46） × 10^6/L, respectively, in which the number of eosinophils in group A was significantly higher than those of group B and C. Also, the number of neutrophils in BALF of group A was even higher than those in group B and C. In addition, the contents of IFN-7 and IL-2 in group A were lower than those in group B and C, but the contents of IL-4 as well as IL-5 were rather higher than those in group B and C. It is evident from the above observations that IL-18 can effectively inhibit the asthmatic inflammatory cells in BALF with an imbalance of the Thl/Th2 cytokines, thus offer- ing the experimental basis for the clinical application of IL-18 in the prevention and treatment of asthma.展开更多
目的:探讨血清肿瘤坏死因子超家族18(tumor necrosis factor superfamily 18,TNFSF18)、血管性血友病因子裂解蛋白酶(a disintegrin and metalloprotease with a thrombospondin type 1 motif member 13,ADAMTS13)、基质相互作用分子1(s...目的:探讨血清肿瘤坏死因子超家族18(tumor necrosis factor superfamily 18,TNFSF18)、血管性血友病因子裂解蛋白酶(a disintegrin and metalloprotease with a thrombospondin type 1 motif member 13,ADAMTS13)、基质相互作用分子1(stromal interaction molecules 1,STIM1)水平预测全膝关节置换术(total knee arthroplasty,TKA)后下肢深静脉血栓形成(deep venous thrombosis,DVT)的价值。方法:选取2020年3月至2024年3月收治的108例拟择期行单侧TKA的患者,术前空腹抽取静脉血,采用ELISA技术测定血清TNFSF18、ADAMTS13、STIM1水平。根据术后是否发生下肢DVT,将患者分为DVT组和非DVT组。采用Logistic回归分析,分析血清TNFSF18、ADAMTS13、STIM1水平与TKA术后下肢DVT的关系,采用受试者操作特征(receiver operating characteristic,ROC)曲线分析血清TNFSF18、ADAMTS13、STIM1水平预测TKA术后下肢DVT的价值。结果:①分组和一般情况组间对比结果。共纳入108例行TKA的患者,术后36例发生下肢DVT(DVT组)、72例未发生下肢DVT(非DVT组)。2组患者的一般情况(性别、年龄、体质量指数、合并高血压情况、合并糖尿病情况、合并高脂血症情况、手术原因、手术时间、术中输血情况、止血带使用时间、术中失血量)比较,组间差异均无统计学意义。②血清TNFSF18、ADAMTS13、STIM1水平与TKA术后下肢DVT关系的分析结果。DVT组的血清TNFSF18、STIM1水平均高于非DVT组(t=6.886,P=0.000;t=6.863,P=0.000),血清ADAMTS13水平低于非DVT组(t=6.531,P=0.000)。多因素Logistic回归分析结果显示,血清TNFSF18、STIM1水平高,以及ADAMTS13水平低均与TKA术后下肢DVT有关[B=0.804,P=0.001,OR=2.234,95%CI(1.393,3.583);B=0.750,P=0.011,OR=2.117,95%CI(1.185,3.782);B=-1.033,P=0.001,OR=0.356,95%CI(0.194,0.654)]。③血清TNFSF18、ADAMTS13、STIM1水平预测TKA术后下肢DVT价值的分析结果。ROC曲线分析结果显示,血清TNFSF18、ADAMTS13、STIM1水平单独及联合预测TKA术后下肢DVT的ROC曲线下面积分别为0.866、0.889、0.817、0.988,三者联合预测的ROC曲线下面积大于三者单独预测(Z=3.621,P=0.000;Z=3.358,P=0.001;Z=3.442,P=0.001)。结论:血清TNFSF18、ADAMTS13、STIM1水平均能较好地预测TKA术后下肢DVT,而且三者联合预测的效能更好。展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.91016013 and 11221202)the Opening Research Fund of State Key Laboratory of Porous Metal Materials(No.PMM-SKL-1-2012)the Project of State Key Laboratory of Explosion Science and Technology(No.SKLEST-13-07)
文摘The hot deformation behavior of TC18 alloy at strain rates ranging from 1 × 10-4 to 1 x 10-2 s-1 and temperatures ranging from 25 to 800 ℃ was studied using a WDW-300 electronic universal testing machine. The relationships between true flow stress decreases with stress and true strain show that the increase of temperature and increases as strain rate increases. The effect of strain rate on the flow stress becomes pronounced at higher temper- atures. At room temperature, the river pattern characteristic of brittle fracture and the dimple pattern typical of ductile fracture are found to exist in different regions of fracture surfaces of the samples. An improved constitutive rela- tionship is proposed to accurately describe the flow stress of TC18 by considering the effect of strain. And a micro- scopic model is also deduced which can link the physical mechanisms to the macroscopic experimental results. A good agreement is obtained between the predictions of the microscopic model and the results of the macroscopic experiment.
基金co-supported by the National Natural Science Foundation of China(Nos.51474375,51275416)the China Postdoctoral Science Foundation(No.2018M633571).
文摘Theα+βdual phase titanium alloys are key structural materials in aviation and aero-space industries,and the complicated flow behavior of these titanium alloys during hot deformation requires to establish a constitutive model incorporating physical mechanism for optimizing process-ing parameters and designing forming tools.This work aims to establish a constitutive model incor-porating physical mechanism for hot deformation of TC18 inα+βphase region.Firstly,the flow behavior and microstructure evolution for hot deformation of TC18 inα+βphase region are char-acterized.The TC18 shows significant strain hardening rate and negative strain hardening exponent around and after peak flow stress,respectively.After peak flow stress,Dynamic Recovery(DRV)mechanism dominates the evolution of a and b phases according to the results of substructure evo-lution.Then,the internal state variables method is applied to establish a constitutive model incor-porating physical mechanism for hot deformation of dual phase titanium alloys.The variation of dislocation density during the hot deformation of titanium alloys is modeled by considering the accumulation of dislocation due to the impediment to dislocation movement by substructure obsta-cles and the annihilation of dislocation due to the dynamic restoration effect.The interaction between dislocations,the subgrain boundaries and the grain/phase boundaries obstruct the disloca-tion movement in the a phase,and the first two obstructs the dislocation movement in the b phase during the hot deformation of TC18.The dislocation annihilation process in theαandβphases dur-ing the hot deformation of TC18 is dominated by DRV.Finally,the substructure evolution in the two phases based constitutive model for hot deformation of TC18 inα+βphase region is presented.This model is well applied to predict the flow stress and quantitively analyze the role of DRV effect in the evolution ofαandβphases during the hot deformation of TC18.
文摘It is an undeniable fact that the success or the failure of any given society or community of human beings depends largely on who controls the affairs of that group.A leader without a clear vision and setting objectives simply drags the group being led into turmoil,while a good leadership paves the way to upward movement of a group of human beings under such a leadership.Searching for a model of good leadership becomes then a serious need in any human society since success is desired by everybody.This study has therefore searched for a recommendable or model of good leadership in the light of Exodus 18:12-27 and African culture.The biblical text was studied as a narrative peace dealing with the change of leadership style by Moses,the ancient leader of the Israelites.He changed from the sole-actor style of leadership to a collaborative and democratic type due to the good advice given to him by Jethro,his father-in-law.This type,in which there was decentralisation of leadership authority,was found to be beneficial to all involved,because the work of the leader(Moses)was made lighter and the led got quicker services.African concepts of leadership were also studied,and it was found out that the African/Igbo democratic style is highly recommendable because it is caring;it has good“listening ears”and excludes dictatorship,without degenerating to the laissez-faire type of leadership.Of the various types of leadership styles examined,the democratic,collaborative type ranks first as recommendable.The Jesus-model of leadership as entailing love and service rather than exploitation,as well as the transparency model of leadership offered by St.Paul in the NT,present themselves as models of good leadership.A good leader serves the interest of the group under his/her charge and not his or her selfish and nepotistic interest.
文摘Based on the theoretical modelling of water-rock δD-δ18O isotopic exchange process,the evolution and sources of ore-forming fluid in four metallogenic epochs of the Jinduicheng su-perlarge-scale porphyry-type molybdenum deposit were investigated. It was revealed that in thepre-metallogenic and early-metallogenic epehs, the ore-forming fluid was a residual fluid derived from magmatic water-wall rock interaction at middle to high temperatures (T = 250 -500℃) and lower W/R ratios (0. 1 > = W/R >0.001 ), while in the metallogenic and Post-metallogenic epochs, the ore-forming nuid was a residual fluid derived from meteoric water-wallrock interaction at midd1e to lower temperatures (T = 150 - 310℃ ) and relatively high W/Rratios (0. 5 >W/R≥0.1 ). The meteoric water played an important role in molybdenum min-eralization, and at the main metallogenic epoch the W/R ratio reached its maximum value.
文摘In order to investigate the effects of interleukin-18 （IL-18） on airway inflammation and the Th1/Th2 cytokine balance in guinea pig asthmatic model as well as its possible mechanisms, the asthmatic model was established by intraperitoneal injection of ovalbumin （OVA） and aerosol challenges into guinea pigs, and 30 treated animals were randomly divided into three groups of 10 animals in each groups, in which group A served as the asthmatic model, group B as the controls and group C as the group treated with IL-18. The counting and categorization of the inflammatory cells in bronchoalveolar lavage fluid （BALF） were performed by using light microscopy, and the contents of cytokines （ IFN-γ, IL- 2, IL-4 and IL-5） were assayed by means of the ELISA kit. The experimental results showed that the numbers of eosinophils （ESO） in BALF of group A, B and C were （97.70 ± 58.03） × 10^6/L, （11.68 × 9.95） × 10^6/L and （28.62 ± 10.46） × 10^6/L, respectively, in which the number of eosinophils in group A was significantly higher than those of group B and C. Also, the number of neutrophils in BALF of group A was even higher than those in group B and C. In addition, the contents of IFN-7 and IL-2 in group A were lower than those in group B and C, but the contents of IL-4 as well as IL-5 were rather higher than those in group B and C. It is evident from the above observations that IL-18 can effectively inhibit the asthmatic inflammatory cells in BALF with an imbalance of the Thl/Th2 cytokines, thus offer- ing the experimental basis for the clinical application of IL-18 in the prevention and treatment of asthma.
文摘目的:探讨血清肿瘤坏死因子超家族18(tumor necrosis factor superfamily 18,TNFSF18)、血管性血友病因子裂解蛋白酶(a disintegrin and metalloprotease with a thrombospondin type 1 motif member 13,ADAMTS13)、基质相互作用分子1(stromal interaction molecules 1,STIM1)水平预测全膝关节置换术(total knee arthroplasty,TKA)后下肢深静脉血栓形成(deep venous thrombosis,DVT)的价值。方法:选取2020年3月至2024年3月收治的108例拟择期行单侧TKA的患者,术前空腹抽取静脉血,采用ELISA技术测定血清TNFSF18、ADAMTS13、STIM1水平。根据术后是否发生下肢DVT,将患者分为DVT组和非DVT组。采用Logistic回归分析,分析血清TNFSF18、ADAMTS13、STIM1水平与TKA术后下肢DVT的关系,采用受试者操作特征(receiver operating characteristic,ROC)曲线分析血清TNFSF18、ADAMTS13、STIM1水平预测TKA术后下肢DVT的价值。结果:①分组和一般情况组间对比结果。共纳入108例行TKA的患者,术后36例发生下肢DVT(DVT组)、72例未发生下肢DVT(非DVT组)。2组患者的一般情况(性别、年龄、体质量指数、合并高血压情况、合并糖尿病情况、合并高脂血症情况、手术原因、手术时间、术中输血情况、止血带使用时间、术中失血量)比较,组间差异均无统计学意义。②血清TNFSF18、ADAMTS13、STIM1水平与TKA术后下肢DVT关系的分析结果。DVT组的血清TNFSF18、STIM1水平均高于非DVT组(t=6.886,P=0.000;t=6.863,P=0.000),血清ADAMTS13水平低于非DVT组(t=6.531,P=0.000)。多因素Logistic回归分析结果显示,血清TNFSF18、STIM1水平高,以及ADAMTS13水平低均与TKA术后下肢DVT有关[B=0.804,P=0.001,OR=2.234,95%CI(1.393,3.583);B=0.750,P=0.011,OR=2.117,95%CI(1.185,3.782);B=-1.033,P=0.001,OR=0.356,95%CI(0.194,0.654)]。③血清TNFSF18、ADAMTS13、STIM1水平预测TKA术后下肢DVT价值的分析结果。ROC曲线分析结果显示,血清TNFSF18、ADAMTS13、STIM1水平单独及联合预测TKA术后下肢DVT的ROC曲线下面积分别为0.866、0.889、0.817、0.988,三者联合预测的ROC曲线下面积大于三者单独预测(Z=3.621,P=0.000;Z=3.358,P=0.001;Z=3.442,P=0.001)。结论:血清TNFSF18、ADAMTS13、STIM1水平均能较好地预测TKA术后下肢DVT,而且三者联合预测的效能更好。
