Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning cal...Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry(DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10 T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope(POM) and X-ray diffraction(XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10 T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10 T, the crystallization rate was increased with the addition of the sebacic acid comonomer.展开更多
The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational flu...The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT,validated with published data,was used to solve the gas-solid multiphase flow of a sandstorm around a train.The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated.Results showed that in sandstorm weather,the drag,lift,side forces and overturning moment increase by variable degrees.Based on a numerical analysis of aerodynamic characteristics,an equation of train stability was also derived using the theory of moment balance from the view of dynamics.A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis.展开更多
A complex micelle as a hemoglobin functional model with the biaoactive function of reversible oxygen transfer has been constructed through the hierarchical assembly of the diblock copolymer poly（ethylene glycol）-blo...A complex micelle as a hemoglobin functional model with the biaoactive function of reversible oxygen transfer has been constructed through the hierarchical assembly of the diblock copolymer poly（ethylene glycol）-block- poly（4-vinylpyridine-co-N-heptyl-4-vinylpyridine） （PEG-b-P（4VP-co-4VPHep））, tetrakis（4-sulfonatophenyl）porphinato iron（II） （Fe（II）TPPS） and β-cyclodextrin （β-CD）. The μ-oxo dimer of Fe（II）TPPS was successfully inhibited because the Fe（II）TPPS was included into the cavities of β-CDs through host-guest interaction. Fe（II）TPPS coordinated with pyridine groups functions as the active site to reversibly bind dioxygen. In adition, the host-guest inclusion （β-CD/Fe（II）TPPS） was encapsulated in the hydrophobic core of the complex micelle and tightly fixed by P4VP chains. The hydrophilic PEG blocks stretched in aqueous solution to constitute the shells which stabilize the structure of the complex micelle as well as endow the complex micelle with sufficient blood circulation time. Dioxygen can be bound to the Fe（II）TPPS located in the confined space and excellent reversibility of the binding-release process of dioxygen can be achieved. The quaternary amine N-heptyl-4-vinylpyridine can coerce abundant S2O4^2- ions into the core of the complex micelle to facilitate the self-reduction process. Dioxygen adducts （Fe（II）TPPS（O2）） were effectively protected by the double hydrophobic barriers constructed by the cavity of the cyclodextrin and the core of the complex micelle which enhances the ability to resist nucleophilic molecules. Therefore, the rationally designed amphiphilic structure can work as a promising artificial O2 carrier. Potentially, the complex micelle can be expected to improve the treatment of diseases linked with hypoxia.展开更多
基金Supported by the National Science and Technology Support Program of China(No.2013BAE02B01)the Special Project on the Integration of Industry,Education and Research of Guangdong Province(No.2013B090500003)the Commissioner Workstation Project of Guangdong Province(No.2014A090906002)
文摘Nylon 10 T and Nylon 10T/1010 samples were synthesized by direct melt polymerization. The non-isothermal crystallization kinetics of Nylon 10 T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry(DSC). Jeziorny equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method, respectively. These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10 T and the Nylon 10T/1010. It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10 T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher. The crystal morphology was observed by means of a polarized optical microscope(POM) and X-ray diffraction(XRD). It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10 T, but also significantly increased the number and decreased the size of spherulites. Comparing with the Nylon 10 T, the crystallization rate was increased with the addition of the sebacic acid comonomer.
基金Project(No.2009BAG12A01-C03) supported by the National Key Technology R&D Program of China
文摘The influence of sandstorms on train aerodynamic performance and safe running was studied in response to the frequent occurrence of sandstorm weather in north China.An Eulerian two-phase model in the computational fluid dynamic (CFD) software FLUENT,validated with published data,was used to solve the gas-solid multiphase flow of a sandstorm around a train.The train aerodynamic performance under different sandstorm levels and no sand conditions was then simulated.Results showed that in sandstorm weather,the drag,lift,side forces and overturning moment increase by variable degrees.Based on a numerical analysis of aerodynamic characteristics,an equation of train stability was also derived using the theory of moment balance from the view of dynamics.A recommended speed limit of a train under different sandstorm levels was calculated based on the stability analysis.
文摘A complex micelle as a hemoglobin functional model with the biaoactive function of reversible oxygen transfer has been constructed through the hierarchical assembly of the diblock copolymer poly（ethylene glycol）-block- poly（4-vinylpyridine-co-N-heptyl-4-vinylpyridine） （PEG-b-P（4VP-co-4VPHep））, tetrakis（4-sulfonatophenyl）porphinato iron（II） （Fe（II）TPPS） and β-cyclodextrin （β-CD）. The μ-oxo dimer of Fe（II）TPPS was successfully inhibited because the Fe（II）TPPS was included into the cavities of β-CDs through host-guest interaction. Fe（II）TPPS coordinated with pyridine groups functions as the active site to reversibly bind dioxygen. In adition, the host-guest inclusion （β-CD/Fe（II）TPPS） was encapsulated in the hydrophobic core of the complex micelle and tightly fixed by P4VP chains. The hydrophilic PEG blocks stretched in aqueous solution to constitute the shells which stabilize the structure of the complex micelle as well as endow the complex micelle with sufficient blood circulation time. Dioxygen can be bound to the Fe（II）TPPS located in the confined space and excellent reversibility of the binding-release process of dioxygen can be achieved. The quaternary amine N-heptyl-4-vinylpyridine can coerce abundant S2O4^2- ions into the core of the complex micelle to facilitate the self-reduction process. Dioxygen adducts （Fe（II）TPPS（O2）） were effectively protected by the double hydrophobic barriers constructed by the cavity of the cyclodextrin and the core of the complex micelle which enhances the ability to resist nucleophilic molecules. Therefore, the rationally designed amphiphilic structure can work as a promising artificial O2 carrier. Potentially, the complex micelle can be expected to improve the treatment of diseases linked with hypoxia.
