The fixture layout is crucial to assure the product quality in a multistation assembly process (MAP). A well-designed fixture layout will make the final product's variability be insensitive to the fixture variation...The fixture layout is crucial to assure the product quality in a multistation assembly process (MAP). A well-designed fixture layout will make the final product's variability be insensitive to the fixture variation inputs. As the basis of the fixture layout design, the design criterion plays an important role in the effectiveness of a solution and the optimization efficiency. In this paper, an effective and efficient design criterion is proposed for the fixture layout with a fixed reference point (FRP) in an MAP. First of all, a state space model for the individual port's variation propagation and accumulation is developed, which is the mathematical foundation of the proposed criterion. Then, based on this model, a novel design criterion used to evaluate the performance of the fixture layout is proposed for the fixture layout with an FRP. Finally, a method extracted from the proposed design criterion is developed for quick fixture layout design. A four-station assembly process is used to validate the effectiveness and efficiency of the proposed models and methods.展开更多
Chitosan (CS) was successfully modified in supercritical carbon dioxide ( scCOz ) by grafting method to enhance its water solubility. In this work, a three.arm star-like fluorinated polymer was synthesized by atom...Chitosan (CS) was successfully modified in supercritical carbon dioxide ( scCOz ) by grafting method to enhance its water solubility. In this work, a three.arm star-like fluorinated polymer was synthesized by atom transfer radical polymerization ( ATRP ) method and applied as a surfactant in supereriticul carbon dioxide (scCO2 ). Then 2-acrylamido-2-methyl propane sulfonie acid (AMPS) was grafted onto CS (CS-g-PAMPS) in H2O/scCO2 inverse emulsion. The effects of mass ratio of water and surfactants (Rw/s ) and pressure of scCO2 on the grafting reaction were investigated. The grafting rate, partide size, and dispersity in water of CS-g-PAMPS varied greatly as Rw/s and pressure of scCO2 changed. It could be found that the value of Rw/s at 12 and the pressure of scCO2 at 30 MPa were the optimum conditions for the grafting reaction. CS-g-PAMPS prepared in this reaction system has higher grafting rate, smaller particle sizes, and better dispersity in water than those prepared via conventional methods.展开更多
Poly[ 2, 2-(m.phenylene) -5, 5-bibenzimidazole] (mPBI) were synthesized by mixing 3, 3', 4, 4'-tetraaminobiphenyl and isophthallc acid in 1 -butyl-3 -methyUmidazolinm chloride ( E BMIM] CI). Intrinsic viscosit...Poly[ 2, 2-(m.phenylene) -5, 5-bibenzimidazole] (mPBI) were synthesized by mixing 3, 3', 4, 4'-tetraaminobiphenyl and isophthallc acid in 1 -butyl-3 -methyUmidazolinm chloride ( E BMIM] CI). Intrinsic viscosity of mPBI polymers was 0.67 dL/g which was measured in 96% sulfuric acid. The polymer was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance ( 1H-NMR ), and thermogravimetric analysis (TGA). The effects of polymerization conditions on the intrinsic viscosity of mPBI were investigated. It showed that the molecular weight of polymer mainly depended on pre-reaction time and reaction temperature. Comparison of structure and properties of mPBI synthesized in ionic liquids(ILs) and polyphosphoric acid was also reported. It indicates that the ionic liquids are a kind of good solvents in synthesis process of m_PBI and ionic liquids mainly affect molecular weight of mPBL展开更多
For complex chemical processes,process optimization is usually performed on causal models from first principle models.When the mechanism models cannot be obtained easily,restricted model built by process data is used ...For complex chemical processes,process optimization is usually performed on causal models from first principle models.When the mechanism models cannot be obtained easily,restricted model built by process data is used for dynamic process optimization.A new strategy is proposed for complex process optimization,in which latent variables are used as decision variables and statistics is used to describe constraints.As the constraint condition will be more complex by projecting the original variable to latent space,Hotelling T^2 statistics is introduced for constraint formulation in latent space.In this way,the constraint is simplified when the optimization is solved in low-dimensional space of latent variable.The validity of the methodology is illustrated in pH-level optimal control process and practical polypropylene grade transition process.展开更多
The Dying Patient Law is very controversial in Israel; there are opinions that the reason for the Law was to prevent the court from making decisions on the subject of end of life according to democratic principles. I ...The Dying Patient Law is very controversial in Israel; there are opinions that the reason for the Law was to prevent the court from making decisions on the subject of end of life according to democratic principles. I decided to do this study because I wanted to know if the legal principles of the Law are democratic as were the court rulings or they are only, or mostly, Jewish principles and meant to prevent a democratic ruling in the courts. The work is a review of the Law and the Dying Patient Committee discussions as well as the chairman's writings on the Law, critique articles, and a review of democratic and bioethical principles. In this project, I have seen that the underlying basis of the Dying Patient Law is Jewish principles and not democratic principles, although Israel is a declared democratic state. This law illustrates the problem in Israel being both a democratic and a Jewish state. It raises the question: What can be done to resolve the conflict between the Jewish principles and democratic and/or bioethical principles?展开更多
An approach was proposed for optimizing beamforming that was based on Support Vector Regression (SVR). After studying the mathematical principal of the SVR algorithm and its primal cost function, the modified cost fun...An approach was proposed for optimizing beamforming that was based on Support Vector Regression (SVR). After studying the mathematical principal of the SVR algorithm and its primal cost function, the modified cost function was first applied to uniform array beamforming, and then the corresponding parameters of the beamforming were optimized. The framework of SVR uniform array beamforming was then established. Simulation results show that SVR beamforming can not only approximate the performance of conventional beamforming in the area without noise and with small data sets, but also improve the generalization ability and reduce the computation burden. Also, the side lobe level of both linear and circular arrays by the SVR algorithm is improved sharply through comparison with the conventional one. SVR beamforming is superior to the conventional method in both linear and circular arrays, under single source or double non-coherent sources.展开更多
Deregulation of power system industry is a very large complex exercise based on respective national energy strategies and policies. A lot of matters and knowledge need to be studied before the idea of deregulation can...Deregulation of power system industry is a very large complex exercise based on respective national energy strategies and policies. A lot of matters and knowledge need to be studied before the idea of deregulation can be implemented. Theoretically, it is said that deregulation can make a large impact to increase efficiency and encourage the competitiveness among related parties. However, to implement the concept of deregulation to electric power supply is very tough challenge. In deregulation environment, regardless of market structure, to know the transmission usage allocation is vital and very a complex problem. Thus, a lot of algorithms have been proposed to overcome it. This paper intends to solve the transmission usage allocation problem using optimization approach. The optimization tool that will be utilized is Genetic Algorithm (GA). GA is probabilistic search technique that has its roots in the principle of genetics and strives for survival. In addition, GA is very robust. Since the nonlinear nature of power flow, it is expected that GA can give optimize results that equitable and acceptable. In this paper, 4-bus and Klos-Kerner 11-bus systems are used for analysis studies. Comparison with other method is also given in this paper.展开更多
Novel environmentally friendly poly(hydroxybutyrate-co-hydroxyvalerate) and poly(ethylene glycol) (PHBV/PEG) copolymer networks were synthesized through free-radical solution polymerization with PHBV diacrylate ...Novel environmentally friendly poly(hydroxybutyrate-co-hydroxyvalerate) and poly(ethylene glycol) (PHBV/PEG) copolymer networks were synthesized through free-radical solution polymerization with PHBV diacrylate (PHBVDA) and polyethylene glycol diacrylate (PEGDA) as macromers. The molecular structure of PHBV/PEG copolymer network was characterized by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR). The morphology of the PHBV/PEG co- polymer network was characterized by polarization optical microscopy. Thermal energy storage properties, thermal reliability and thermal stability were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis. The results indicated that the PHBV/PEG copolymer network hindered the growth of PEG crystalline segments or PHBV segments. PHBV/PEG copolymer network had a higher latent heat enthalpy, which didn't reduce with the components of PHBV in- creased. Moreover, PHBV/PEG copolymer network still had good thermal stability even at 300 ~C. These results suggested that such environmentally friendly copolymer network would have wide applications in phase change energy storage materials.展开更多
Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic...Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy and their thermal properties, viscosities, electrochemical windows, and ionic conductivities were systematically measured. With adding one of these compounds (1 vol. %, DSC3N1) in the baseline electrolyte 1.0 M LiPF 6 in EC: DEC (1:1, in volume), Li/LiCoO 2 half cell tests showed an improved cyclability after 100 cycles and improved rate capability at 5C rate condition. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopic (EDS) analysis confirmed the acid scavenging function and film forming capability of DSC3N1. These results demonstrated that the multifunctional organosilicon compounds have considerable potential as additives for use in lithium-ion batteries.展开更多
The cation exchange mechanism was further investigated during the extraction of Sr 2+ and Cs+ using the extractant dicyclo- hexano-18-crown-6 (DCH18C6) in an ionic liquid (IL)1-ethyl-3-methyimidazolium bis[(trifluorom...The cation exchange mechanism was further investigated during the extraction of Sr 2+ and Cs+ using the extractant dicyclo- hexano-18-crown-6 (DCH18C6) in an ionic liquid (IL)1-ethyl-3-methyimidazolium bis[(trifluoromethyl)sulfonyl]imide (C2 mimNTf2 ). The concentrations of both the cation C2 mim + and the anion NTf2 in aqueous phase were detected. The con-centration of NTf2 in the aqueous phase decreased as Sr2+ or Cs+ exchanged into the IL phase. Addition of C2 mim + or NTf2 as well as the variation of the solubility of C2 mimNTf2 influenced the extraction efficiency of Sr2+ or Cs+ .展开更多
A facile method was used to prepare gold-platinum (Au-Pt) catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts...A facile method was used to prepare gold-platinum (Au-Pt) catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles (AuPtNPs) since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite (PG) were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy (Ea) for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts (electrodeposited on the PG) offer less activation energy (ca. 9.500 kJ mo1-1) than the bare PG (ca. 10.345 kJ mol-1). The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.展开更多
Cefazolin sodium can form both α- and β-form crystals. It also can form dehydrated crystalline and amorphous products through different production processes. Because different polymorphic medicines usually have diff...Cefazolin sodium can form both α- and β-form crystals. It also can form dehydrated crystalline and amorphous products through different production processes. Because different polymorphic medicines usually have different physical and chemical properties, it is critical to emphasize the crystallization control of polymorphic medicines. Near-infrared (NIR) analysis, which incorporates a combination of NIR spectroscopic techniques and multivariate chemometric methods, is considered a powerful tool for the determination of the crystallinity of polymorphic drugs. The selection of optimal spectral ranges that correlate with the lattice specificity and content specificity is crucial to obtaining a specific NIR model. In the present work, near-infrared (NIR) spectra of cefazolin sodium with different crystal forms created through different processes were studied. The results suggest that wavelengths within the range of 9102.7-8597.5 cm-1 is related to the specificity of the cefazolin sodium crystal lattice and that the range of 6001.6-5496.4 cm i is associated with the quantitative content of cefazolin sodium. The two ab- sorptions are caused by the second overtone of the C-H stretching band (3nC-H) and the first overtone of C-H stretching band (2uC-H), respectively. Using these results, we established a suitable method of constructing a universal quantitative model by using mixed samples in different crystal forms as a calibration set, selecting a content-specific range (6001.6-5496.4 cm-l), and adding lattice-related spectral ranges where appropriate. This may provide a framework for the construction of prediction models for polymorphic medicines.展开更多
A sub-micron structured film with a poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube array has been prepared by a series of electrodeposition processes, and a semiconductor-sensitized solar ...A sub-micron structured film with a poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube array has been prepared by a series of electrodeposition processes, and a semiconductor-sensitized solar cell based on this structure was also fabricated. Vertically oriented ZnO sub-micron tubes were obtained on an indium tin oxide (ITO) substrate, and then CdTe nanocrystals and a thin P3MT layer were electrodeposited sequentially onto the walls of the ZnO sub-micron tubes. A suitable thickness of CdTe and P3MT could improve the photovoltaic properties of the solar cell, which was attributed to the enhancement in the light absorption and the decrease in the recombination of photogenerated carriers. In addition, a p–n heterojunction formed between the interface of CdTe and P3MT played an important part in the efficient separation and fast transport of photogenerated carriers in the sub-micron structure. A power conversion efficiency of 1.20% was obtained with this type of solar cell.展开更多
The microscopic behaviors of a water layer on different monolayers (SAMs) are studied by molecular dynamics hydrophilic and hydrophobic surfaces of well ordered self-assembled simulations. The SAMs consist of 18-car...The microscopic behaviors of a water layer on different monolayers (SAMs) are studied by molecular dynamics hydrophilic and hydrophobic surfaces of well ordered self-assembled simulations. The SAMs consist of 18-carbon alkyl chains bound to a silicon(111) substrate, and the characteristic of its surface is tuned from hydrophobic to hydrophilic by using different terminal functional groups (-CH3, -COOH). In the simulation, the properties of water membranes adjacent to the surfaces of SAMs were reported by comparing pure water in mobility, structure, and orientational ordering of water molecules. The results sug- gest that the mobility of water molecules adjacent to hydrophilic surface becomes weaker and the molecules have a better or- dering. The distribution of hydrogen bonds indicates that the number of water-water hydrogen bonds per water molecule tends to be lower. However, the mobility of water molecules and distribution of hydrogen bonds of a water membrane in hydropho- bic system are nearly the same as those in pure water system. In addition, hydrogen bonds are mainly formed between the hy- droxyl of the COOH group and water molecules in a hydrophilic system, which is helpful in understanding the structure of in- terfacial water.展开更多
Diethylamine, di-n-hexylamine, dicyclohexylamine and triethylamine have been used as initiators for the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG NCA) to synthesize poly(γ-benzyl...Diethylamine, di-n-hexylamine, dicyclohexylamine and triethylamine have been used as initiators for the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG NCA) to synthesize poly(γ-benzyl-L-glutamate) (PBLG). The relationship between the molecular weight of PBLG and the molar ratio of monomer and initiator was studied. With dicy- clohexylamine as initiator, the influence of monomer concentration, and reaction temperature and time on the polymerization of BLG NCA was examined. Three reagents were used for the deprotection of benzyl groups in PBLG, including hydrobromic acid/acetic acid (33 wt.%), NaOH aqueous solution and trimethylsilyl iodide (TMSI). Through examining the molecular weight of PLGA obtained using different deprotection methods, it was revealed that TMSI could minimize chain cleavage in the process of deprotection and retain the degree of polymerization. The biocompatibilities of PBLG obtained using different initiators were evaluated by a live/dead assay against L929 fibroblast cells. The in vitro cytotoxicities of PLGA obtained using different deprotecting agents were evaluated by a methyl thiazolyl tetrazolium assay. The results revealed that both PBLG and PLGA exhibited good biocompatibilities.展开更多
With the development of nanosciences, both localized surface plasmon resonance light scattering (LSPR-LS) and dynamic light scattering (DLS) techniques have been widely used for quantitative purposes with high sen...With the development of nanosciences, both localized surface plasmon resonance light scattering (LSPR-LS) and dynamic light scattering (DLS) techniques have been widely used for quantitative purposes with high sensitivity. In this contribution, we make a comparison of the two light scattering techniques by employing gold nanoparticles (AuNPs) aggregation induced by mercuric ions. It was found that citrate-stabilized AuNPs got aggregated in aqueous medium in the presence of mercuric ions through a chelation process, resulting in greatly enhanced LSPR-LS signals and increased hydrodynamic diameter. The enhanced LSPR-LS intensity (A/) is proportional to the concentration of mercuric ions in the range of 0.4-2.5 laM following the linear regression equation of A/= -84.7+516.4c, with the correlation coefficient of 0.983 (n = 6) and the limit of determi- nation (3o-) about 0.10 gM. On the other hand, the increased hydrodynamic diameter can be identified by the DLS signals only with a concentration of Hg2+ in the range of 1.0-2.5 gM, and a linear relationship between the average hydrodynamic diame- ters of the resulted aggregates and the concentration of Hg2+ can be expressed as d = -6.16 + 45.9c with the correlation coeffi- cient of 0.994. In such case, LSPR-LS signals were further applied to the selective determination of mercuric ions in lake water samples with high sensitivity and simple operation.展开更多
基金National Nature Science Foundation of China(No.71201025)Specialized Research Fund for the Doctoral Program of Higher Education,China(No.20110092120007)Jiangsu Key Laboratory of Equipments Detection and Control,China(No.JSKLEDC201215)
文摘The fixture layout is crucial to assure the product quality in a multistation assembly process (MAP). A well-designed fixture layout will make the final product's variability be insensitive to the fixture variation inputs. As the basis of the fixture layout design, the design criterion plays an important role in the effectiveness of a solution and the optimization efficiency. In this paper, an effective and efficient design criterion is proposed for the fixture layout with a fixed reference point (FRP) in an MAP. First of all, a state space model for the individual port's variation propagation and accumulation is developed, which is the mathematical foundation of the proposed criterion. Then, based on this model, a novel design criterion used to evaluate the performance of the fixture layout is proposed for the fixture layout with an FRP. Finally, a method extracted from the proposed design criterion is developed for quick fixture layout design. A four-station assembly process is used to validate the effectiveness and efficiency of the proposed models and methods.
基金National Natural Science Foundation of China(No.20674017)Shanghai Key Laboratory Project of China(No.08DZ2230500)
文摘Chitosan (CS) was successfully modified in supercritical carbon dioxide ( scCOz ) by grafting method to enhance its water solubility. In this work, a three.arm star-like fluorinated polymer was synthesized by atom transfer radical polymerization ( ATRP ) method and applied as a surfactant in supereriticul carbon dioxide (scCO2 ). Then 2-acrylamido-2-methyl propane sulfonie acid (AMPS) was grafted onto CS (CS-g-PAMPS) in H2O/scCO2 inverse emulsion. The effects of mass ratio of water and surfactants (Rw/s ) and pressure of scCO2 on the grafting reaction were investigated. The grafting rate, partide size, and dispersity in water of CS-g-PAMPS varied greatly as Rw/s and pressure of scCO2 changed. It could be found that the value of Rw/s at 12 and the pressure of scCO2 at 30 MPa were the optimum conditions for the grafting reaction. CS-g-PAMPS prepared in this reaction system has higher grafting rate, smaller particle sizes, and better dispersity in water than those prepared via conventional methods.
基金Natural Science Foundation of Shanghai,China(No.09ZR1401500)
文摘Poly[ 2, 2-(m.phenylene) -5, 5-bibenzimidazole] (mPBI) were synthesized by mixing 3, 3', 4, 4'-tetraaminobiphenyl and isophthallc acid in 1 -butyl-3 -methyUmidazolinm chloride ( E BMIM] CI). Intrinsic viscosity of mPBI polymers was 0.67 dL/g which was measured in 96% sulfuric acid. The polymer was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance ( 1H-NMR ), and thermogravimetric analysis (TGA). The effects of polymerization conditions on the intrinsic viscosity of mPBI were investigated. It showed that the molecular weight of polymer mainly depended on pre-reaction time and reaction temperature. Comparison of structure and properties of mPBI synthesized in ionic liquids(ILs) and polyphosphoric acid was also reported. It indicates that the ionic liquids are a kind of good solvents in synthesis process of m_PBI and ionic liquids mainly affect molecular weight of mPBL
基金Supported by the National Natural Science Foundation of China(61174114)the Research Fund for the Doctoral Program of Higher Education in China(20120101130016)+1 种基金the Natural Science Foundation of Zhejiang Province(LQ15F030006)the Educational Commission Research Program of Zhejiang Province(Y201431412)
文摘For complex chemical processes,process optimization is usually performed on causal models from first principle models.When the mechanism models cannot be obtained easily,restricted model built by process data is used for dynamic process optimization.A new strategy is proposed for complex process optimization,in which latent variables are used as decision variables and statistics is used to describe constraints.As the constraint condition will be more complex by projecting the original variable to latent space,Hotelling T^2 statistics is introduced for constraint formulation in latent space.In this way,the constraint is simplified when the optimization is solved in low-dimensional space of latent variable.The validity of the methodology is illustrated in pH-level optimal control process and practical polypropylene grade transition process.
文摘The Dying Patient Law is very controversial in Israel; there are opinions that the reason for the Law was to prevent the court from making decisions on the subject of end of life according to democratic principles. I decided to do this study because I wanted to know if the legal principles of the Law are democratic as were the court rulings or they are only, or mostly, Jewish principles and meant to prevent a democratic ruling in the courts. The work is a review of the Law and the Dying Patient Committee discussions as well as the chairman's writings on the Law, critique articles, and a review of democratic and bioethical principles. In this project, I have seen that the underlying basis of the Dying Patient Law is Jewish principles and not democratic principles, although Israel is a declared democratic state. This law illustrates the problem in Israel being both a democratic and a Jewish state. It raises the question: What can be done to resolve the conflict between the Jewish principles and democratic and/or bioethical principles?
基金the Foundation of Returned Scholar of Shaanxi Province(SLZ2008006)
文摘An approach was proposed for optimizing beamforming that was based on Support Vector Regression (SVR). After studying the mathematical principal of the SVR algorithm and its primal cost function, the modified cost function was first applied to uniform array beamforming, and then the corresponding parameters of the beamforming were optimized. The framework of SVR uniform array beamforming was then established. Simulation results show that SVR beamforming can not only approximate the performance of conventional beamforming in the area without noise and with small data sets, but also improve the generalization ability and reduce the computation burden. Also, the side lobe level of both linear and circular arrays by the SVR algorithm is improved sharply through comparison with the conventional one. SVR beamforming is superior to the conventional method in both linear and circular arrays, under single source or double non-coherent sources.
文摘Deregulation of power system industry is a very large complex exercise based on respective national energy strategies and policies. A lot of matters and knowledge need to be studied before the idea of deregulation can be implemented. Theoretically, it is said that deregulation can make a large impact to increase efficiency and encourage the competitiveness among related parties. However, to implement the concept of deregulation to electric power supply is very tough challenge. In deregulation environment, regardless of market structure, to know the transmission usage allocation is vital and very a complex problem. Thus, a lot of algorithms have been proposed to overcome it. This paper intends to solve the transmission usage allocation problem using optimization approach. The optimization tool that will be utilized is Genetic Algorithm (GA). GA is probabilistic search technique that has its roots in the principle of genetics and strives for survival. In addition, GA is very robust. Since the nonlinear nature of power flow, it is expected that GA can give optimize results that equitable and acceptable. In this paper, 4-bus and Klos-Kerner 11-bus systems are used for analysis studies. Comparison with other method is also given in this paper.
基金financially supported by the National Natural Science Foundation for Distinguished Young Scholar of China (50925312)the National Natural Science Foundation of China(50873022)+2 种基金the Shanghai Nano Special Projects (1052nm02800)the Programme of Talents of Discipline to University (111-2-04)the Specialized Research Fund for the Doctoral Program of Higher Education(20100075110007)
文摘Novel environmentally friendly poly(hydroxybutyrate-co-hydroxyvalerate) and poly(ethylene glycol) (PHBV/PEG) copolymer networks were synthesized through free-radical solution polymerization with PHBV diacrylate (PHBVDA) and polyethylene glycol diacrylate (PEGDA) as macromers. The molecular structure of PHBV/PEG copolymer network was characterized by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR). The morphology of the PHBV/PEG co- polymer network was characterized by polarization optical microscopy. Thermal energy storage properties, thermal reliability and thermal stability were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis. The results indicated that the PHBV/PEG copolymer network hindered the growth of PEG crystalline segments or PHBV segments. PHBV/PEG copolymer network had a higher latent heat enthalpy, which didn't reduce with the components of PHBV in- creased. Moreover, PHBV/PEG copolymer network still had good thermal stability even at 300 ~C. These results suggested that such environmentally friendly copolymer network would have wide applications in phase change energy storage materials.
基金supported by the National Natural Science Foundation of China (50973112)the Hundred Talents Program of Chinese Academy of Sciences (CAS)+1 种基金CAS-Guangdong Collaboration Program (20108)Guangzhou Municipal Science & Technology Project (11A44061500)
文摘Aminoalkylsilanes with oligo(ethylene oxide) units were designed and synthesized as multifunctional electrolyte additives for lithium-ion batteries. The chemical structures were fully characterized by nuclear magnetic resonance (NMR) spectroscopy and their thermal properties, viscosities, electrochemical windows, and ionic conductivities were systematically measured. With adding one of these compounds (1 vol. %, DSC3N1) in the baseline electrolyte 1.0 M LiPF 6 in EC: DEC (1:1, in volume), Li/LiCoO 2 half cell tests showed an improved cyclability after 100 cycles and improved rate capability at 5C rate condition. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopic (EDS) analysis confirmed the acid scavenging function and film forming capability of DSC3N1. These results demonstrated that the multifunctional organosilicon compounds have considerable potential as additives for use in lithium-ion batteries.
基金supported by National Natural Science Foundation of China(20871009)the Fundamental Research Funds for the Central Universities
文摘The cation exchange mechanism was further investigated during the extraction of Sr 2+ and Cs+ using the extractant dicyclo- hexano-18-crown-6 (DCH18C6) in an ionic liquid (IL)1-ethyl-3-methyimidazolium bis[(trifluoromethyl)sulfonyl]imide (C2 mimNTf2 ). The concentrations of both the cation C2 mim + and the anion NTf2 in aqueous phase were detected. The con-centration of NTf2 in the aqueous phase decreased as Sr2+ or Cs+ exchanged into the IL phase. Addition of C2 mim + or NTf2 as well as the variation of the solubility of C2 mimNTf2 influenced the extraction efficiency of Sr2+ or Cs+ .
基金financially supported by a Research University Grant(1001/PKIMIA/811056)financial support from Universiti Sains Malaysia
文摘A facile method was used to prepare gold-platinum (Au-Pt) catalysts by direct electrodeposition via cyclic voltammetry in an acidic medium. Various parameters that affect the properties of electrodeposited catalysts were investigated such as initial ap- plied potential, scan rate and deposition time. Initial applied potential plays a more important role in the preparation of bime- tallic nanoparticles (AuPtNPs) since the kinetics of electrodeposition is in competition with the rate of hydrogen evolution. The AuPtNPs electrodeposited on pencil graphite (PG) were used to study the electrooxidation of hydroquinone. Various parame- ters such as pH, scan rate, concentration of hydroquinone and temperature were studied in the electrooxidation process. Ap- parent activation energy (Ea) for the electrooxidation of hydroquinone, calculated from the Arrhenius plot, shows that AuPtNPs catalysts (electrodeposited on the PG) offer less activation energy (ca. 9.500 kJ mo1-1) than the bare PG (ca. 10.345 kJ mol-1). The AuPtNPs/PG shows better catalytic performance than the PG electrode due to the greater surface area it provides, thus re- sulting in more active sites available for adsorption of hydroquinone molecules on the surface of the catalyst.
基金the National Key New Drug R&D Program Foundation of China (2010ZX09401-403) for the financial support
文摘Cefazolin sodium can form both α- and β-form crystals. It also can form dehydrated crystalline and amorphous products through different production processes. Because different polymorphic medicines usually have different physical and chemical properties, it is critical to emphasize the crystallization control of polymorphic medicines. Near-infrared (NIR) analysis, which incorporates a combination of NIR spectroscopic techniques and multivariate chemometric methods, is considered a powerful tool for the determination of the crystallinity of polymorphic drugs. The selection of optimal spectral ranges that correlate with the lattice specificity and content specificity is crucial to obtaining a specific NIR model. In the present work, near-infrared (NIR) spectra of cefazolin sodium with different crystal forms created through different processes were studied. The results suggest that wavelengths within the range of 9102.7-8597.5 cm-1 is related to the specificity of the cefazolin sodium crystal lattice and that the range of 6001.6-5496.4 cm i is associated with the quantitative content of cefazolin sodium. The two ab- sorptions are caused by the second overtone of the C-H stretching band (3nC-H) and the first overtone of C-H stretching band (2uC-H), respectively. Using these results, we established a suitable method of constructing a universal quantitative model by using mixed samples in different crystal forms as a calibration set, selecting a content-specific range (6001.6-5496.4 cm-l), and adding lattice-related spectral ranges where appropriate. This may provide a framework for the construction of prediction models for polymorphic medicines.
基金supported by the National Natural Science Foundation of China (NSFC, Grant nos. 21173065, 20573031)the Ministry of Science and Technology of China (MSTC, Grant no. 2011CB808702)the Natural Science Foundation of Hebei Province of China (Grant no.B2010000856)
文摘A sub-micron structured film with a poly(3-methylthiophene) (P3MT)-modified CdTe/ZnO shell-core sub-micron tube array has been prepared by a series of electrodeposition processes, and a semiconductor-sensitized solar cell based on this structure was also fabricated. Vertically oriented ZnO sub-micron tubes were obtained on an indium tin oxide (ITO) substrate, and then CdTe nanocrystals and a thin P3MT layer were electrodeposited sequentially onto the walls of the ZnO sub-micron tubes. A suitable thickness of CdTe and P3MT could improve the photovoltaic properties of the solar cell, which was attributed to the enhancement in the light absorption and the decrease in the recombination of photogenerated carriers. In addition, a p–n heterojunction formed between the interface of CdTe and P3MT played an important part in the efficient separation and fast transport of photogenerated carriers in the sub-micron structure. A power conversion efficiency of 1.20% was obtained with this type of solar cell.
基金financially supported by the National Science Foundation of Shandong Province (ZR2011BZ0003)the National Natural Science Foundation of China (21173128)
文摘The microscopic behaviors of a water layer on different monolayers (SAMs) are studied by molecular dynamics hydrophilic and hydrophobic surfaces of well ordered self-assembled simulations. The SAMs consist of 18-carbon alkyl chains bound to a silicon(111) substrate, and the characteristic of its surface is tuned from hydrophobic to hydrophilic by using different terminal functional groups (-CH3, -COOH). In the simulation, the properties of water membranes adjacent to the surfaces of SAMs were reported by comparing pure water in mobility, structure, and orientational ordering of water molecules. The results sug- gest that the mobility of water molecules adjacent to hydrophilic surface becomes weaker and the molecules have a better or- dering. The distribution of hydrogen bonds indicates that the number of water-water hydrogen bonds per water molecule tends to be lower. However, the mobility of water molecules and distribution of hydrogen bonds of a water membrane in hydropho- bic system are nearly the same as those in pure water system. In addition, hydrogen bonds are mainly formed between the hy- droxyl of the COOH group and water molecules in a hydrophilic system, which is helpful in understanding the structure of in- terfacial water.
基金financially supported by the National Natural Science Foundation of China (50973060, 51173101, 51003055, 51233004, 51273196,50973108 and 51203153)the Science and Technology Commission of Shanghai Municipality (11JC1404200)the Innovation Program of Shanghai Municipal Education Commission (11YZ06)
文摘Diethylamine, di-n-hexylamine, dicyclohexylamine and triethylamine have been used as initiators for the ring-opening polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG NCA) to synthesize poly(γ-benzyl-L-glutamate) (PBLG). The relationship between the molecular weight of PBLG and the molar ratio of monomer and initiator was studied. With dicy- clohexylamine as initiator, the influence of monomer concentration, and reaction temperature and time on the polymerization of BLG NCA was examined. Three reagents were used for the deprotection of benzyl groups in PBLG, including hydrobromic acid/acetic acid (33 wt.%), NaOH aqueous solution and trimethylsilyl iodide (TMSI). Through examining the molecular weight of PLGA obtained using different deprotection methods, it was revealed that TMSI could minimize chain cleavage in the process of deprotection and retain the degree of polymerization. The biocompatibilities of PBLG obtained using different initiators were evaluated by a live/dead assay against L929 fibroblast cells. The in vitro cytotoxicities of PLGA obtained using different deprotecting agents were evaluated by a methyl thiazolyl tetrazolium assay. The results revealed that both PBLG and PLGA exhibited good biocompatibilities.
基金supported by the National Natural Science Foundation of China (21035005)
文摘With the development of nanosciences, both localized surface plasmon resonance light scattering (LSPR-LS) and dynamic light scattering (DLS) techniques have been widely used for quantitative purposes with high sensitivity. In this contribution, we make a comparison of the two light scattering techniques by employing gold nanoparticles (AuNPs) aggregation induced by mercuric ions. It was found that citrate-stabilized AuNPs got aggregated in aqueous medium in the presence of mercuric ions through a chelation process, resulting in greatly enhanced LSPR-LS signals and increased hydrodynamic diameter. The enhanced LSPR-LS intensity (A/) is proportional to the concentration of mercuric ions in the range of 0.4-2.5 laM following the linear regression equation of A/= -84.7+516.4c, with the correlation coefficient of 0.983 (n = 6) and the limit of determi- nation (3o-) about 0.10 gM. On the other hand, the increased hydrodynamic diameter can be identified by the DLS signals only with a concentration of Hg2+ in the range of 1.0-2.5 gM, and a linear relationship between the average hydrodynamic diame- ters of the resulted aggregates and the concentration of Hg2+ can be expressed as d = -6.16 + 45.9c with the correlation coeffi- cient of 0.994. In such case, LSPR-LS signals were further applied to the selective determination of mercuric ions in lake water samples with high sensitivity and simple operation.