CAD/CAE/CAM的技术的出现对传统的模具设计方式带来了新的突破。提高注射成型CAE的模拟计算精度,是个很重要的问题。聚合物参数P V T对CAE的模拟计算精度以及成型的品质有很大的影响,因此如何测量聚合物P V T参数和绘制P V T曲线,对... CAD/CAE/CAM的技术的出现对传统的模具设计方式带来了新的突破。提高注射成型CAE的模拟计算精度,是个很重要的问题。聚合物参数P V T对CAE的模拟计算精度以及成型的品质有很大的影响,因此如何测量聚合物P V T参数和绘制P V T曲线,对注射成型CAE有重要意义。展开更多
The derivative expressions between activation energy (E) and the temperature at the maximum mass loss rate(Tmax) and between activation energy (E) and exponent (N) were deduced in the light of Arrhenius theory. It was...The derivative expressions between activation energy (E) and the temperature at the maximum mass loss rate(Tmax) and between activation energy (E) and exponent (N) were deduced in the light of Arrhenius theory. It was found that the increase of activation energy results in the decrease of exponent and the increase of Tmax. The kinetic parameters were involved in the analysis of the thermal degradation of several polymers. The degradation kinetics of these polymers well complied with the prediction of the derivative expressions for the polymer degradation with single mechanism dominated.展开更多
2004年1月2日出版的《SCIENCE》杂志发表了上海交通大学化学化工学院颜德岳教授及其博士生周永丰、侯健的论文《Supramolecular Self-Assembly of Macroscopic Tubes》。该论文在国际上率先报道了宏观超分子自组装现象，由一类新型的不...2004年1月2日出版的《SCIENCE》杂志发表了上海交通大学化学化工学院颜德岳教授及其博士生周永丰、侯健的论文《Supramolecular Self-Assembly of Macroscopic Tubes》。该论文在国际上率先报道了宏观超分子自组装现象，由一类新型的不规则的超支化共聚物自组装得到了厘米长度、毫米直径的多壁螺旋管，将自发超分子自组装研究领域拓展到了宏观尺度，使我国在该研究领域处于国际领先的地位。展开更多
The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature a...The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.展开更多
Paclitaxel(PTX) is an effective anticancer drug with poor solubility in water.Recently,much effort has been devoted into alternative formulations of PTX for improving its aqueous solubility.In this study,PTX and poly(...Paclitaxel(PTX) is an effective anticancer drug with poor solubility in water.Recently,much effort has been devoted into alternative formulations of PTX for improving its aqueous solubility.In this study,PTX and poly(L-lactic acid)(PLLA) were co-precipitated by a supercritical antisolvent(SAS) process using dichloromethane(DCM) and the mixtures of DCM/ethanol(EtOH) or DCM/dimethyl sulfoxide(DMSO) as the solvent,with super-critical carbon dioxide as the antisolvent.The effects of solvent,solvent ratio,temperature,pressure,polymer con-centration and solution flow rate on particle morphology,mass median diameter(Dp50) and PTX loading were in-vestigated using single-factor method.The particle samples were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),laser diffraction particle size analyzer and high pressure liquid chromatogra-phy(HPLC).XRD results indicate that the micronized PTX is dispersed into the PLLA matrix in an amorphous form.SEM indicates that the solvent and the solvent ratio have great effect on the particle morphologies,and particle morphology is good at the volume ratio of DCM/EtOH of 50/50.For the mixed DCM/EtOH solvent,Dp50 increases with the increase of the temperature,pressure,PLLA concentration and solution flow rate,and PTX loading in-creases with pressure.Suitable operating conditions for the experimental system are as follows:DCM/EtOH 50/50(by volume),35 ℃,10-12 MPa,PLLA concentration of 5 g·L-1 and solution flow rate of 0.5 ml·min-1.展开更多
Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhous...Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhouse experiment was conducted to investigate effects of wheat straw biochar （0-160 mL L-1） and super absorbent polymer （SAP, 0.8 g L-1） on physical and chemical properties of a substrate based on spent pig litter compost and the growth of water spinach （Ipomoea aquatica Forsk）. Total porosity, water-holding capacity~ pH and electrical conductivity （EC） of the substrate significantly increased with increasing biochar rates, especially in the substrate without SAP. The values of pH and EC were significantly lower in the substrate with SAP than those without SAP at the high biochar application rates （100-160 mL L-l）. The germination rates of water spinach decreased with increasing biochar rates when biochar was added alone （76.9%-83.7%）, whereas the rates increased to 83.6%-85.8% when biochar was added in combination with SAP. Growth parameters of water spinach and nutrient uptake by shoots and roots increased with increasing biochar rates and reached the maximum values at the biochar rate of 100 mL L-1. There were significant cubic relationships between the uptake of nutrients （N, P, and K） and biochar rates, both with and without SAP addition. In order to avoid negative effects on plant growth, the biochar application rate should be controlled at an optimal level （100 mL L-1 ）. The SAP addition not only enhanced the positive effects of biochar application on the properties of the substrate, but also inhibited the excessive rise of pH and EC following biochar additions, which led to better plant growth and enhanced nutrient uptakes by water spinach.展开更多
We study the free energy fluctuations for a mixture of directed polymers, which was first introduced by Borodin et al. （2015） to investigate the limiting distribution of a stationary Kaxdar-Parisi-Zhang （KPZ） equa...We study the free energy fluctuations for a mixture of directed polymers, which was first introduced by Borodin et al. （2015） to investigate the limiting distribution of a stationary Kaxdar-Parisi-Zhang （KPZ） equation. The main results consist of both the law of large numbers and the asymptotic fluctuation for the free energy as the model size tends to infinity. In particular, we find the explicit values （which may depend on model parameters） of normalizing constants in the fluctuation. This shows that such a mixture model is in the KPZ university class.展开更多
文摘The derivative expressions between activation energy (E) and the temperature at the maximum mass loss rate(Tmax) and between activation energy (E) and exponent (N) were deduced in the light of Arrhenius theory. It was found that the increase of activation energy results in the decrease of exponent and the increase of Tmax. The kinetic parameters were involved in the analysis of the thermal degradation of several polymers. The degradation kinetics of these polymers well complied with the prediction of the derivative expressions for the polymer degradation with single mechanism dominated.
文摘2004年1月2日出版的《SCIENCE》杂志发表了上海交通大学化学化工学院颜德岳教授及其博士生周永丰、侯健的论文《Supramolecular Self-Assembly of Macroscopic Tubes》。该论文在国际上率先报道了宏观超分子自组装现象，由一类新型的不规则的超支化共聚物自组装得到了厘米长度、毫米直径的多壁螺旋管，将自发超分子自组装研究领域拓展到了宏观尺度，使我国在该研究领域处于国际领先的地位。
文摘The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.
基金Supported by the National Natural Science Foundation of China (21076084)the Fundamental Research Funds for the Central Universities (2011ZZ0006)the Open Project Program of Provincial Key Laboratory of Green Processing Technology and Product Safety of Natural Products
文摘Paclitaxel(PTX) is an effective anticancer drug with poor solubility in water.Recently,much effort has been devoted into alternative formulations of PTX for improving its aqueous solubility.In this study,PTX and poly(L-lactic acid)(PLLA) were co-precipitated by a supercritical antisolvent(SAS) process using dichloromethane(DCM) and the mixtures of DCM/ethanol(EtOH) or DCM/dimethyl sulfoxide(DMSO) as the solvent,with super-critical carbon dioxide as the antisolvent.The effects of solvent,solvent ratio,temperature,pressure,polymer con-centration and solution flow rate on particle morphology,mass median diameter(Dp50) and PTX loading were in-vestigated using single-factor method.The particle samples were characterized using X-ray diffraction(XRD),scanning electron microscopy(SEM),laser diffraction particle size analyzer and high pressure liquid chromatogra-phy(HPLC).XRD results indicate that the micronized PTX is dispersed into the PLLA matrix in an amorphous form.SEM indicates that the solvent and the solvent ratio have great effect on the particle morphologies,and particle morphology is good at the volume ratio of DCM/EtOH of 50/50.For the mixed DCM/EtOH solvent,Dp50 increases with the increase of the temperature,pressure,PLLA concentration and solution flow rate,and PTX loading in-creases with pressure.Suitable operating conditions for the experimental system are as follows:DCM/EtOH 50/50(by volume),35 ℃,10-12 MPa,PLLA concentration of 5 g·L-1 and solution flow rate of 0.5 ml·min-1.
基金supported by the National Natural Science Foundation of China (No.41401259)the General Financial Grant from the China Postdoctoral Science Foundation (No.2014M551528)+1 种基金the Independent Innovation Project of Jiangsu Province,China (No.CX(14)2035)the Special Scientific Research Fund of Agricultural Public Welfare Profession of China (No.201203050)
文摘Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhouse experiment was conducted to investigate effects of wheat straw biochar （0-160 mL L-1） and super absorbent polymer （SAP, 0.8 g L-1） on physical and chemical properties of a substrate based on spent pig litter compost and the growth of water spinach （Ipomoea aquatica Forsk）. Total porosity, water-holding capacity~ pH and electrical conductivity （EC） of the substrate significantly increased with increasing biochar rates, especially in the substrate without SAP. The values of pH and EC were significantly lower in the substrate with SAP than those without SAP at the high biochar application rates （100-160 mL L-l）. The germination rates of water spinach decreased with increasing biochar rates when biochar was added alone （76.9%-83.7%）, whereas the rates increased to 83.6%-85.8% when biochar was added in combination with SAP. Growth parameters of water spinach and nutrient uptake by shoots and roots increased with increasing biochar rates and reached the maximum values at the biochar rate of 100 mL L-1. There were significant cubic relationships between the uptake of nutrients （N, P, and K） and biochar rates, both with and without SAP addition. In order to avoid negative effects on plant growth, the biochar application rate should be controlled at an optimal level （100 mL L-1 ）. The SAP addition not only enhanced the positive effects of biochar application on the properties of the substrate, but also inhibited the excessive rise of pH and EC following biochar additions, which led to better plant growth and enhanced nutrient uptakes by water spinach.
基金supported by National Natural Science Foundation of China (Grant No. 11371317)the Fundamental Research Funds for the Central Universities
文摘We study the free energy fluctuations for a mixture of directed polymers, which was first introduced by Borodin et al. （2015） to investigate the limiting distribution of a stationary Kaxdar-Parisi-Zhang （KPZ） equation. The main results consist of both the law of large numbers and the asymptotic fluctuation for the free energy as the model size tends to infinity. In particular, we find the explicit values （which may depend on model parameters） of normalizing constants in the fluctuation. This shows that such a mixture model is in the KPZ university class.
