A new technological process of tube forming was developed, namely solution treatment → granule medium internal high pressure forming → artificial aging. During this process, the mechanical properties of AA6061 tube ...A new technological process of tube forming was developed, namely solution treatment → granule medium internal high pressure forming → artificial aging. During this process, the mechanical properties of AA6061 tube can be adjusted by heat treatment to satisfy the process requirements and the processing method can also be realized by granule medium internal high pressure forming technology with the features of convenient implementation, low requirement to equipment and flexible design in product. Results show that, at a solution temperature of 560 ℃ and time of 120 min, the elongation of AA6061 increases by 313%, but the strength and the hardness dramatically decrease. At an aging temperature of 180 ℃ and time of 360 min, the strength and hardness of AA6061 alloy are recovered to the values of the as-received alloy. The maximum expansion ratio（MER） of AA6061 tube increases by 25.5% and the material properties of formed tube reach the performances of raw material.展开更多
The asymptotic behaviour of laminar forced convection in a circular duct, for a Herschel-Bulkley fluid with constant properties, is analysed by taking into account the viscous dissipation effects. The axial heat condu...The asymptotic behaviour of laminar forced convection in a circular duct, for a Herschel-Bulkley fluid with constant properties, is analysed by taking into account the viscous dissipation effects. The axial heat conduction in the fluid is neglected. The asymptotic temperature field and the asymptotic value of the Nusselt number are determined for every boundary condition that allows a fully developed region. Comparisons with other existing solutions for Newtonian and non-Newtonian cases are presented.展开更多
To investigate the epidemiological status of extended spectrum β lactamase (ESBL) producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) and the drug resistance profiles of such organisms ...To investigate the epidemiological status of extended spectrum β lactamase (ESBL) producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) and the drug resistance profiles of such organisms Methods A total of 282 clinical isolates of E coli and 180 of K pneumoniae were collected from different districts of Zhejiang Province Inhibitor potentiated broth dilution tests were performed for detecting extended spectrum β lactamases Etests were performed to detect the drug resistance of these strains against nine commonly used antibiotics Results The prevalence of extended spectrum β lactamases in E coli and K pneumoniae was 34 0% and 38 3%, respectively The average prevalence of extended spectrum β lactamases in E coli and K pneumoniae was 35 7% The resistance prevalence of extended spectrum β lactamase producing strains to ceftazidime and cefotaxime was 40% and 26% respectively, so were those to cefepime, cefoxitin, piperacillin tazobactam, cefoperazone sulbactam, amikacin and ciprofloxacin All these strains were sensitive to imipenem Conclusion The results in this study showed that the prevalence of extended spectrum β lactamases was high, while extended spectrum β lactamase producing strains were resistant to most antimicrobial agents except imipenem展开更多
The chemical structure of end groups influenced the phase transition temperature of thermoresponsive polymers. We demonstrated a strategy for the preparation of the pH/thermo-responsive polymeric nanoparticles via sub...The chemical structure of end groups influenced the phase transition temperature of thermoresponsive polymers. We demonstrated a strategy for the preparation of the pH/thermo-responsive polymeric nanoparticles via subtle modification of end groups of thermoresponsive polymer segments with a carboxyl group and revealed its potential application for enhanced intracellular drug delivery. By developing a polymeric nanoparticle composed of poly(aliphatic ester) as the inner core and thermoresponsive polyphosphoester as the outer shell, we showed that end groups of thermoresponsive polyphosphoester segments modified by carboxyl groups exhibited a pH/thermo-responsive behavior due to the hydrophilic to hydrophobic transitions of the end groups in response to the pH. Moreover, by encapsulating doxorubicin into the hydrophobic core of such pH/thermo-responsive polymer nanoparticles, their intracellular delivery and cytotoxicity to wild-type and drug-resistant tumor cells were significantly enhanced through the phase-transition-dependent drug release that was triggered by endosomal/lysosomal pH. This novel strategy and the multi-responsive polymer nanoparticles achieved by the subtle chain-terminal modification of thermoresponsive polymers provide a smart platform for biomedical applications.展开更多
基金Project(51775481)supported by the National Natural Science Foundation of ChinaProject(A2016002017)supported by the High-level Talents Program of Heibei Province,China
文摘A new technological process of tube forming was developed, namely solution treatment → granule medium internal high pressure forming → artificial aging. During this process, the mechanical properties of AA6061 tube can be adjusted by heat treatment to satisfy the process requirements and the processing method can also be realized by granule medium internal high pressure forming technology with the features of convenient implementation, low requirement to equipment and flexible design in product. Results show that, at a solution temperature of 560 ℃ and time of 120 min, the elongation of AA6061 increases by 313%, but the strength and the hardness dramatically decrease. At an aging temperature of 180 ℃ and time of 360 min, the strength and hardness of AA6061 alloy are recovered to the values of the as-received alloy. The maximum expansion ratio（MER） of AA6061 tube increases by 25.5% and the material properties of formed tube reach the performances of raw material.
文摘The asymptotic behaviour of laminar forced convection in a circular duct, for a Herschel-Bulkley fluid with constant properties, is analysed by taking into account the viscous dissipation effects. The axial heat conduction in the fluid is neglected. The asymptotic temperature field and the asymptotic value of the Nusselt number are determined for every boundary condition that allows a fully developed region. Comparisons with other existing solutions for Newtonian and non-Newtonian cases are presented.
文摘To investigate the epidemiological status of extended spectrum β lactamase (ESBL) producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) and the drug resistance profiles of such organisms Methods A total of 282 clinical isolates of E coli and 180 of K pneumoniae were collected from different districts of Zhejiang Province Inhibitor potentiated broth dilution tests were performed for detecting extended spectrum β lactamases Etests were performed to detect the drug resistance of these strains against nine commonly used antibiotics Results The prevalence of extended spectrum β lactamases in E coli and K pneumoniae was 34 0% and 38 3%, respectively The average prevalence of extended spectrum β lactamases in E coli and K pneumoniae was 35 7% The resistance prevalence of extended spectrum β lactamase producing strains to ceftazidime and cefotaxime was 40% and 26% respectively, so were those to cefepime, cefoxitin, piperacillin tazobactam, cefoperazone sulbactam, amikacin and ciprofloxacin All these strains were sensitive to imipenem Conclusion The results in this study showed that the prevalence of extended spectrum β lactamases was high, while extended spectrum β lactamase producing strains were resistant to most antimicrobial agents except imipenem
基金supported by the Ministry of Science and Technology of China(2010CB934001)the National Natural Science Foundation of China(51125012,51203145)
文摘The chemical structure of end groups influenced the phase transition temperature of thermoresponsive polymers. We demonstrated a strategy for the preparation of the pH/thermo-responsive polymeric nanoparticles via subtle modification of end groups of thermoresponsive polymer segments with a carboxyl group and revealed its potential application for enhanced intracellular drug delivery. By developing a polymeric nanoparticle composed of poly(aliphatic ester) as the inner core and thermoresponsive polyphosphoester as the outer shell, we showed that end groups of thermoresponsive polyphosphoester segments modified by carboxyl groups exhibited a pH/thermo-responsive behavior due to the hydrophilic to hydrophobic transitions of the end groups in response to the pH. Moreover, by encapsulating doxorubicin into the hydrophobic core of such pH/thermo-responsive polymer nanoparticles, their intracellular delivery and cytotoxicity to wild-type and drug-resistant tumor cells were significantly enhanced through the phase-transition-dependent drug release that was triggered by endosomal/lysosomal pH. This novel strategy and the multi-responsive polymer nanoparticles achieved by the subtle chain-terminal modification of thermoresponsive polymers provide a smart platform for biomedical applications.
