The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact...The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.展开更多
Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were de...Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were determined by a split Hopkinson pressure bar （SHPB） test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.展开更多
[Objective] The aim was to study the sequence of aroA gene （synthetic gene in metabolic pathway of aromatic amino acids） of a pathogenic bacterium （Flavobacterium johnsoniae） causing gill-rote disease.[Method] Gen...[Objective] The aim was to study the sequence of aroA gene （synthetic gene in metabolic pathway of aromatic amino acids） of a pathogenic bacterium （Flavobacterium johnsoniae） causing gill-rote disease.[Method] Genomic DNA of strain M165 of F.johnsoniae was used as a template,three specific nested primers of 5＇end and 3＇end and arbitrary primer were used to amplify the aroA gene of strain M165 through Thermal asymmetric interlaced PCR （TAIL-PCR）.And the obtained sequence was analyzed.[Result] The electrophoresis determination result showed that the size of amplified product was consist with the expected product; sequencing analysis suggested that the full-length of aroA gene was 1 230 bp,enconding 410 amino acids.The amino acid sequence of aroA protein showed the highest level of similarity to amino acids sequence of aroA protein of F.johnsoniae.[Conclusion] TAIL-PCR provided a simple and efficient new method for the cloning of the gene sequence.Obtaining of full-length of aroA gene provided a foundation for further investigation on the effects of nutrition correlation factors such as aroA on the virulence of and virulence of F.johnsoniae.展开更多
抑制关系: 保持联系(keep in touch)卡包含了一系列的高速数据和传真调制解调电路,处理速度高达115.2Kbps(千位/秒)。这些小巧轻便的调制解调器遵照PCMCIA和JEIDA标准而适用于新一代的笔记本式计算机,掌上机,和便携机中。其先进的功能包...抑制关系: 保持联系(keep in touch)卡包含了一系列的高速数据和传真调制解调电路,处理速度高达115.2Kbps(千位/秒)。这些小巧轻便的调制解调器遵照PCMCIA和JEIDA标准而适用于新一代的笔记本式计算机,掌上机,和便携机中。其先进的功能包括,广泛的可连接性(具有有线和无线通讯能力)。展开更多
AIM: To determine the overall prevalence of H pylori and CagA positive H pylori infection and the prevalence of other bacterial and viral causes of chronic infection in patients with coronary heart disease (CHD), and ...AIM: To determine the overall prevalence of H pylori and CagA positive H pylori infection and the prevalence of other bacterial and viral causes of chronic infection in patients with coronary heart disease (CHD), and the potential role of anti-heat-shock protein 60 (Hsp60) anti- body response to these proteins in increasing the risk of CHD development. METHODS: Eighty patients with CHD and 160 controls were employed. We also compared the levels of anti- heat-shock protein 60 (Hsp60) antibodies in the two groups. The H pylori infection and the CagA status were determined serologically, using commercially available enzyme-linked immunosorbent assays (ELISA), and a Western blotting method developed in our laboratory. Systemic antibodies to Hsp60 were determined by a sandwich ELISA, using a polyclonal antibody to Hsp60 to sensitise polystyrene plates and a commercially available human Hsp60 as an antigen. RESULTS: The overall prevalence of H pylori infec- tion was 78.7% (n = 63) in patients and 76.2% (n = 122) in controls (P = 0.07). Patients infected by CagA- positive (CagA+) H pylori strains were 71.4% (n = 45) vs 52.4% of infected controls (P = 0.030, OR = 2.27). Sys-temic levels of IgG to Hsp60 were increased in H pylori- negative patients compared with uninfected controls (P < 0.001) and CagA-positive infected patients compared with CagA-positive infected controls (P = 0.007). CONCLUSION: CagA positive H pylori infection may concur to the development of CHD; high levels of anti- Hsp60 antibodies may constitute a marker and/or a con- comitant pathogenic factor of the disease.展开更多
抽油机日常维护过程中,为保证采油树井口不渗不漏,通常将盘根压得较紧,导致光杆与盘根间摩擦力增大,从而使抽油机电动机耗电量及盘根消耗量增加。为了掌握盘根在不同松紧状态下抽油机井的能耗情况,进行了盘根盒调整扭矩的多次试验,总结...抽油机日常维护过程中,为保证采油树井口不渗不漏,通常将盘根压得较紧,导致光杆与盘根间摩擦力增大,从而使抽油机电动机耗电量及盘根消耗量增加。为了掌握盘根在不同松紧状态下抽油机井的能耗情况,进行了盘根盒调整扭矩的多次试验,总结出盘根不同松紧度对能耗的影响规律。通过试验确定出光杆微带油状态为最节能状态,现场对比5644井次,共节电218.4×104k Wh,平均单井日节电1.06 k Wh,年创经济效益128.125万元;并制定了合理光杆盘根松紧度判定标准,使盘根管理进入常态化,达到在实际应用中节能降耗的目的。展开更多
基金Project (51001014) supported by the Young Scientists Fund of the National Natural Science Foundation of China
文摘The dynamic fracture behaviors of Ti-6Al-4V alloy at high strain rate loading were investigated systemically through Taylor impact test, over the range of impact velocities from 145 m/s to 306 m/s. The critical impact velocity of fracture ranges from 217 m/s to 236 m/s. Smooth surfaces and ductile dimple areas were observed on the fracture surfaces. As the impact velocity reached 260 m/s, the serious melting regions were also observed on the fracture surfaces. Self-organization of cracks emerges when the impact velocity reaches 260 m/s, while some special cracks whose ＂tips＂ are not sharp but arc and smooth, and without any evidence of deformation or adiabatic shear band were also observed on the impact end surfaces. Examination of the sections of these special cracks reveals that the cracks expand along the two maximum shear stress directions respectively, and finally intersect as a tridimensional ＂stagger ridge＂ structure.
基金Project(2012 DFG51540)supported by the Ministry of Science and Technology of China
文摘Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were determined by a split Hopkinson pressure bar （SHPB） test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.
基金Supported by The Natural Science Foundation of Guangdong Province(06024033)National Special Fund for the Agricultural Commonweal Industry(200803013)Earmarked Fund for Modern Agroindustry Technology Research System(nycytx-49-14)~~
文摘[Objective] The aim was to study the sequence of aroA gene （synthetic gene in metabolic pathway of aromatic amino acids） of a pathogenic bacterium （Flavobacterium johnsoniae） causing gill-rote disease.[Method] Genomic DNA of strain M165 of F.johnsoniae was used as a template,three specific nested primers of 5＇end and 3＇end and arbitrary primer were used to amplify the aroA gene of strain M165 through Thermal asymmetric interlaced PCR （TAIL-PCR）.And the obtained sequence was analyzed.[Result] The electrophoresis determination result showed that the size of amplified product was consist with the expected product; sequencing analysis suggested that the full-length of aroA gene was 1 230 bp,enconding 410 amino acids.The amino acid sequence of aroA protein showed the highest level of similarity to amino acids sequence of aroA protein of F.johnsoniae.[Conclusion] TAIL-PCR provided a simple and efficient new method for the cloning of the gene sequence.Obtaining of full-length of aroA gene provided a foundation for further investigation on the effects of nutrition correlation factors such as aroA on the virulence of and virulence of F.johnsoniae.
文摘抑制关系: 保持联系(keep in touch)卡包含了一系列的高速数据和传真调制解调电路,处理速度高达115.2Kbps(千位/秒)。这些小巧轻便的调制解调器遵照PCMCIA和JEIDA标准而适用于新一代的笔记本式计算机,掌上机,和便携机中。其先进的功能包括,广泛的可连接性(具有有线和无线通讯能力)。
基金Supported by a grant from the University of Siena, PAR 2004 "H pylori infection, hosts’ aplotypes of inflammatory cytokines and the risk of ischemic heart disease"
文摘AIM: To determine the overall prevalence of H pylori and CagA positive H pylori infection and the prevalence of other bacterial and viral causes of chronic infection in patients with coronary heart disease (CHD), and the potential role of anti-heat-shock protein 60 (Hsp60) anti- body response to these proteins in increasing the risk of CHD development. METHODS: Eighty patients with CHD and 160 controls were employed. We also compared the levels of anti- heat-shock protein 60 (Hsp60) antibodies in the two groups. The H pylori infection and the CagA status were determined serologically, using commercially available enzyme-linked immunosorbent assays (ELISA), and a Western blotting method developed in our laboratory. Systemic antibodies to Hsp60 were determined by a sandwich ELISA, using a polyclonal antibody to Hsp60 to sensitise polystyrene plates and a commercially available human Hsp60 as an antigen. RESULTS: The overall prevalence of H pylori infec- tion was 78.7% (n = 63) in patients and 76.2% (n = 122) in controls (P = 0.07). Patients infected by CagA- positive (CagA+) H pylori strains were 71.4% (n = 45) vs 52.4% of infected controls (P = 0.030, OR = 2.27). Sys-temic levels of IgG to Hsp60 were increased in H pylori- negative patients compared with uninfected controls (P < 0.001) and CagA-positive infected patients compared with CagA-positive infected controls (P = 0.007). CONCLUSION: CagA positive H pylori infection may concur to the development of CHD; high levels of anti- Hsp60 antibodies may constitute a marker and/or a con- comitant pathogenic factor of the disease.
文摘抽油机日常维护过程中,为保证采油树井口不渗不漏,通常将盘根压得较紧,导致光杆与盘根间摩擦力增大,从而使抽油机电动机耗电量及盘根消耗量增加。为了掌握盘根在不同松紧状态下抽油机井的能耗情况,进行了盘根盒调整扭矩的多次试验,总结出盘根不同松紧度对能耗的影响规律。通过试验确定出光杆微带油状态为最节能状态,现场对比5644井次,共节电218.4×104k Wh,平均单井日节电1.06 k Wh,年创经济效益128.125万元;并制定了合理光杆盘根松紧度判定标准,使盘根管理进入常态化,达到在实际应用中节能降耗的目的。
