In this paper an error in[4]is pointed out and a method for constructingsurface interpolating scattered data points is presented.The main feature of the methodin this paper is that the surface so constructed is polyno...In this paper an error in[4]is pointed out and a method for constructingsurface interpolating scattered data points is presented.The main feature of the methodin this paper is that the surface so constructed is polynomial,which makes the construction simple and the calculation easy.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
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
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
New methods for carbon-carbon (C-C) forming reactions are constantly emerging in the field of organic synthesis. In this review, a brief history followed by recent developments of decarbonylative C-C forming reactions...New methods for carbon-carbon (C-C) forming reactions are constantly emerging in the field of organic synthesis. In this review, a brief history followed by recent developments of decarbonylative C-C forming reactions mediated by transition metals is described. Many different substrates are presented and the review is organized by the different carbonyl precursors, such as acyl chlorides, aldehydes, anhydrides, esters and ketones, used in the respective transformations. Furthermore, the broad scope of these reactions is exhibited by the application to several reaction types (e.g. Heck-type reactions, Suzuki cross-coupling type reactions, C-H activation, etc.) as well as a natural product synthesis (e.g. muscroride A). While several examples are provided, this review marks the beginning of a new field that is still in its infancy and for what might be a new approach to achieve highly efficient reactions that come closer to meeting the standards of chemical economies (e.g. atom, redox, step, etc.) and green chemistry.展开更多
To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to inves- tigate the potential mobility of CO2 dissolved in brines over a wide range of spatial an...To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to inves- tigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distribu- tions in geological media. In this work, the mass transfer of aqueous CO2 in brines has been investigated by means of a chemi- cal potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equa- tion of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interracial concen- tration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2-disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high.展开更多
A series of novel 2H-pyrazolo[4,3-c]hexahydropyridine derivatives （II） have been designed and synthesized. The target com- pounds have been identified by elemental analysis and spectral （1H NMR, IR, and MS） data a...A series of novel 2H-pyrazolo[4,3-c]hexahydropyridine derivatives （II） have been designed and synthesized. The target com- pounds have been identified by elemental analysis and spectral （1H NMR, IR, and MS） data and the absolute configuration of compound （IIl） was confirmed by single crystal X-ray diffraction. The cytotoxicity of the target compounds have been evalu- ated in vitro against two human breast cancer cell lines MCF-7 and MDA-MB-231 by MTT assay. Most compounds exhibited good inhibition, and compounds II21 （IC50 = 4.7 μM for MCF-7 and IC50 = 9.3 μM for MDA-MB-231）, 1133 （IC50 = 2.4 μM for MCF-7 and IC50 = 4.2 gM for MDA-MB-231） and 114o （IC50 = 3.3 μM for MCF-7 and IC5o =8.6 μM for MDA-MB-231） dis- played better inhibitory activity than 5-fluorouracil （IC50 = 4.8 μM for MCF-7 and IC50 = 9.6 I, tM for MDA-MB-231, respec- tively）. Flow cytometric analysis and DNA fragmentation suggest that II33 is cytotoxic and able to induce the apoptosis of MCF-7 cells. The fluorescence properties of compounds IIl, II6, II11,II16, II23, Il2s, and II3s were also studied and compound Ilzs afforded the highest photoluminescence quantum yield （38%）.展开更多
Copper catalysts supported on metal oxides display unique efficiency and selectivity in catalyzing glycerol hydrogenolysis to propanediols. Understanding the reaction at the molecular level is the key to rational desi...Copper catalysts supported on metal oxides display unique efficiency and selectivity in catalyzing glycerol hydrogenolysis to propanediols. Understanding the reaction at the molecular level is the key to rational design of better catalysts for propanediol synthesis, which is one of the major challenges for glycerol application in energy. In this work, extensive calculations based on periodic density functional theory were carried out to study thermodynamics of glycerol hydrogenolysis over binary model catalysts, including Cu/ZrO2 and Cu/MgO, with the focus to elucidate the competitive reaction pathways to produce the 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO). Our results suggest that the reaction starts with glycerol dehydration on the metal oxide, followed by sequential hydrogenation over metal centers. Based on our explorations on the stabilities of adsorbed reactants, dehydrated intermediates and hydrogenated species along the reaction channels, the DFT calculations show that the 1,2-PDO formation will dominate in comparison to the 1,3-PDO from thermodynamic viewpoint. This is consistent with our experiments where the Cu catalysts seem to give the 1,2-PDO as a main product. The calculations and experiments also indicate that the Cu/MgO exhibits superior activities than Cu/ZrO2 for the hydrogenolysis of glycerol molecules.展开更多
Visible light irradiation combined with homogeneous iron and/or hydrogen peroxide to degrade organic dye rhodamine B (RhB) and small molecular compound 2,4-dichlorophenol (2,4-DCP) in a home-made bottle reactor was as...Visible light irradiation combined with homogeneous iron and/or hydrogen peroxide to degrade organic dye rhodamine B (RhB) and small molecular compound 2,4-dichlorophenol (2,4-DCP) in a home-made bottle reactor was assessed. The concen-tration of oxidize species, Fe3+ and Fe2+ were determined during the degradation process. The results demonstrated that visible light irradiation combined with electro-Fenton improved the degradation efficiency. Moreover, both RhB and 2,4-DCP were mineralized during visible light synergistic electro-Fenton oxidation process. 95.0% TOC (total organic carbon) removal rate of RhB occurred after 90 min and 96.7% of COD (chemical oxygen demand) removal rate after 65 min of irradiation. 91.3% TOC removal rate of 2,4-DCP occurred after 16 h of irradiation and 99.9% COD removal rate occurred after 12 h of illumination. The degradation and oxidation process was dominated by the hydroxyl radical ( · OH) generated in the system. Both the impressed electricity and dye sensitization by visible light facilitated the conversion between Fe3+ and Fe 2+ , thus, improving Fenton reaction efficiency.展开更多
A novel fluid micromixer based on pneumatic perturbation and passive structures was developed. This micromixer facilitates integration and is applicable to fluid mixing over a wide range of flow rates. The microfluidi...A novel fluid micromixer based on pneumatic perturbation and passive structures was developed. This micromixer facilitates integration and is applicable to fluid mixing over a wide range of flow rates. The microfluidic mixing device consists of an S-shaped structure with two mixing chambers and two barriers, and two pneumatic chambers designed over the S-shaped channel. The performance of the micromixer for fluids with wide variation of flow rates was significantly improved owing to the integration of the pneumatic mixing components with the passive mixing structures. The mixing mechanism of the passive mixing structures was explored by numerical simulation, and the influencing factors on the mixing efficiency were investigated. The results showed that when using a gas pressure of 0.26 MPa and a 100 pm-thick polydimethylsiloxane （PDMS） pneumatic diaphragm, the mixing of fluids with flow rates ranging from 1 to 650 ~tL/min was achieved with a pumping frequency of 50 Hz. Fast synthesis of CdS quantum dots was realized using this device. Smaller particles were obtained, and the size distribu- tion was greatly improved compared with those obtained using conventional methods.展开更多
Curing behaviors of the unsaturated polyester resin （UPR） containing 1-1.8 wt% methyl ethyl ketone peroxide （MEKP） initia- tor are investigated. The viscosity, gelation and vitrification transition of the UPR-MEKP...Curing behaviors of the unsaturated polyester resin （UPR） containing 1-1.8 wt% methyl ethyl ketone peroxide （MEKP） initia- tor are investigated. The viscosity, gelation and vitrification transition of the UPR-MEKP systems are examined using the ro- tating viscometer and differential scanning calorimetry （DSC）. A liquid fragility parameter, Me, defined as the viscosity varia- tion rate of the liquids towards the curing temperature is presented. It is found that Mc has a good negative relation with the glass transition temperature （Tg） in the systems. Mc can be used for predicting the stability of the cured amorphous systems. The relationship between the liquid and cured thermoset polymer systems is studied from both the thermodynamic and kinetic point of view.展开更多
文摘In this paper an error in[4]is pointed out and a method for constructingsurface interpolating scattered data points is presented.The main feature of the methodin this paper is that the surface so constructed is polynomial,which makes the construction simple and the calculation easy.
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.
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UT Austin and CPRIT for a start-up fundthe Welch Foundation for research grants
文摘New methods for carbon-carbon (C-C) forming reactions are constantly emerging in the field of organic synthesis. In this review, a brief history followed by recent developments of decarbonylative C-C forming reactions mediated by transition metals is described. Many different substrates are presented and the review is organized by the different carbonyl precursors, such as acyl chlorides, aldehydes, anhydrides, esters and ketones, used in the respective transformations. Furthermore, the broad scope of these reactions is exhibited by the application to several reaction types (e.g. Heck-type reactions, Suzuki cross-coupling type reactions, C-H activation, etc.) as well as a natural product synthesis (e.g. muscroride A). While several examples are provided, this review marks the beginning of a new field that is still in its infancy and for what might be a new approach to achieve highly efficient reactions that come closer to meeting the standards of chemical economies (e.g. atom, redox, step, etc.) and green chemistry.
基金Lule University of Technology for the financial support the financial support from the Swedish Research Council+2 种基金the National Basic Research Program of China (2009CB226103,2009CB623400)the National Natural Science Foundation of China(50808039)the Natural Science Foundation of Jiangsu Province,China (BK2009138)
文摘To investigate long-term CO2 behavior in geological formations and quantification of possible CO2 leaks, it is crucial to inves- tigate the potential mobility of CO2 dissolved in brines over a wide range of spatial and temporal scales and density distribu- tions in geological media. In this work, the mass transfer of aqueous CO2 in brines has been investigated by means of a chemi- cal potential gradient model based on non-equilibrium thermodynamics in which the statistical associating fluid theory equa- tion of state was used to calculate the fugacity coefficient of CO2 in brine. The investigation shows that the interracial concen- tration of aqueous CO2 and the corresponding density both increase with increasing pressure and decreasing temperature; the effective diffusion coefficients decrease initially and then increase with increasing pressure; and the density of the CO2-disolved brines increases with decreasing CO2 pressure in the CO2 dissolution process. The aqueous CO2 concentration profiles obtained by the chemical potential gradient model are considerably different from those obtained by the concentration gradient model, which shows the importance of considering non-ideality, especially when the pressure is high.
基金supported by Zooblast-molecular Biology Laboratory of Shanghai Normal Universitysupported by the National Natural Science Foundation of China (21042010, 21102092 and30870560)+4 种基金the Key Scientific "Twelfth Five-Year" National Technology Support Program (2011BAE06B01-17)the Innovation Project of Shanghai Education Commission (12YZ078)the Key Project of the Science and Technology Commission of Shanghai 105405503400)the Leading Academic Discipline Project of Shanghai Normal University (DZL808)Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University (07dz22303)
文摘A series of novel 2H-pyrazolo[4,3-c]hexahydropyridine derivatives （II） have been designed and synthesized. The target com- pounds have been identified by elemental analysis and spectral （1H NMR, IR, and MS） data and the absolute configuration of compound （IIl） was confirmed by single crystal X-ray diffraction. The cytotoxicity of the target compounds have been evalu- ated in vitro against two human breast cancer cell lines MCF-7 and MDA-MB-231 by MTT assay. Most compounds exhibited good inhibition, and compounds II21 （IC50 = 4.7 μM for MCF-7 and IC50 = 9.3 μM for MDA-MB-231）, 1133 （IC50 = 2.4 μM for MCF-7 and IC50 = 4.2 gM for MDA-MB-231） and 114o （IC50 = 3.3 μM for MCF-7 and IC5o =8.6 μM for MDA-MB-231） dis- played better inhibitory activity than 5-fluorouracil （IC50 = 4.8 μM for MCF-7 and IC50 = 9.6 I, tM for MDA-MB-231, respec- tively）. Flow cytometric analysis and DNA fragmentation suggest that II33 is cytotoxic and able to induce the apoptosis of MCF-7 cells. The fluorescence properties of compounds IIl, II6, II11,II16, II23, Il2s, and II3s were also studied and compound Ilzs afforded the highest photoluminescence quantum yield （38%）.
基金the financial support from the Natural Science Foundation of Shandong Province (ZR2010BQ001 and O92003110C)the National Natural Science Foundation of China (20803038)
文摘Copper catalysts supported on metal oxides display unique efficiency and selectivity in catalyzing glycerol hydrogenolysis to propanediols. Understanding the reaction at the molecular level is the key to rational design of better catalysts for propanediol synthesis, which is one of the major challenges for glycerol application in energy. In this work, extensive calculations based on periodic density functional theory were carried out to study thermodynamics of glycerol hydrogenolysis over binary model catalysts, including Cu/ZrO2 and Cu/MgO, with the focus to elucidate the competitive reaction pathways to produce the 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO). Our results suggest that the reaction starts with glycerol dehydration on the metal oxide, followed by sequential hydrogenation over metal centers. Based on our explorations on the stabilities of adsorbed reactants, dehydrated intermediates and hydrogenated species along the reaction channels, the DFT calculations show that the 1,2-PDO formation will dominate in comparison to the 1,3-PDO from thermodynamic viewpoint. This is consistent with our experiments where the Cu catalysts seem to give the 1,2-PDO as a main product. The calculations and experiments also indicate that the Cu/MgO exhibits superior activities than Cu/ZrO2 for the hydrogenolysis of glycerol molecules.
基金supported by China National Funds for Distinguished Young Scientists (50925932)the National Natural Science Foundation of China (21177072, 21207079)Open Foundation about Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission& Ministry of Education of Hubei Province (CHCL10007)
文摘Visible light irradiation combined with homogeneous iron and/or hydrogen peroxide to degrade organic dye rhodamine B (RhB) and small molecular compound 2,4-dichlorophenol (2,4-DCP) in a home-made bottle reactor was assessed. The concen-tration of oxidize species, Fe3+ and Fe2+ were determined during the degradation process. The results demonstrated that visible light irradiation combined with electro-Fenton improved the degradation efficiency. Moreover, both RhB and 2,4-DCP were mineralized during visible light synergistic electro-Fenton oxidation process. 95.0% TOC (total organic carbon) removal rate of RhB occurred after 90 min and 96.7% of COD (chemical oxygen demand) removal rate after 65 min of irradiation. 91.3% TOC removal rate of 2,4-DCP occurred after 16 h of irradiation and 99.9% COD removal rate occurred after 12 h of illumination. The degradation and oxidation process was dominated by the hydroxyl radical ( · OH) generated in the system. Both the impressed electricity and dye sensitization by visible light facilitated the conversion between Fe3+ and Fe 2+ , thus, improving Fenton reaction efficiency.
基金financially supported by the Natural Science Foundation of China (20975019, 21075013, 21235001)the Program of New Century Excellent Talents in University (NCET-09-0274)the Fundamental Research Funds for the Central Universities (N100405003, N100605002,N110805001, N110705002)
文摘A novel fluid micromixer based on pneumatic perturbation and passive structures was developed. This micromixer facilitates integration and is applicable to fluid mixing over a wide range of flow rates. The microfluidic mixing device consists of an S-shaped structure with two mixing chambers and two barriers, and two pneumatic chambers designed over the S-shaped channel. The performance of the micromixer for fluids with wide variation of flow rates was significantly improved owing to the integration of the pneumatic mixing components with the passive mixing structures. The mixing mechanism of the passive mixing structures was explored by numerical simulation, and the influencing factors on the mixing efficiency were investigated. The results showed that when using a gas pressure of 0.26 MPa and a 100 pm-thick polydimethylsiloxane （PDMS） pneumatic diaphragm, the mixing of fluids with flow rates ranging from 1 to 650 ~tL/min was achieved with a pumping frequency of 50 Hz. Fast synthesis of CdS quantum dots was realized using this device. Smaller particles were obtained, and the size distribu- tion was greatly improved compared with those obtained using conventional methods.
基金the financial support from the National Natural Science Foundation of China ( 50831003)
文摘Curing behaviors of the unsaturated polyester resin （UPR） containing 1-1.8 wt% methyl ethyl ketone peroxide （MEKP） initia- tor are investigated. The viscosity, gelation and vitrification transition of the UPR-MEKP systems are examined using the ro- tating viscometer and differential scanning calorimetry （DSC）. A liquid fragility parameter, Me, defined as the viscosity varia- tion rate of the liquids towards the curing temperature is presented. It is found that Mc has a good negative relation with the glass transition temperature （Tg） in the systems. Mc can be used for predicting the stability of the cured amorphous systems. The relationship between the liquid and cured thermoset polymer systems is studied from both the thermodynamic and kinetic point of view.
