Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the...Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) catalyst.These findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.展开更多
Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.E...Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.EC is also the most widely used electrolyte solvent in sodium ion batteries.However,compared to lithium metal,sodium metal(Na)shows higher activity and reacts violently with EC-based electrolyte(NaPF_(6)as solute),which leads to the failure of sodium metal batteries(SMBs).Herein,we reveal the electrochemical instability mechanism of EC on sodium metal battery,and find that the com-bination of EC and NaPF_(6) is electrically reduced in sodium metal anode during charging,resulting in the reduction of the first coulombic efficiency,and the continuous consumption of electrolyte leads to the cell failure.To address the above issues,an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes.Specifically,ethyl methyl carbonate(EMC)and dimethyl carbon-ate(DMC)as solvents and fluoroethylene carbonate(FEC)as SEI-forming additive have been identified as the optimal solvent for NaFP_(6)based electrolyte and used in Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))/Na batteries.The batter-ies exhibit excellent capacity retention rate of about 80%over 1000 cycles at a cut-off voltage of 4.3 V.展开更多
Three new Zn（Ⅱ）/Cd（Ⅱ） coordination polymers based on 2-mercaptonicotinic acid （H2mna） with 1,2-di（4-pyridyl）ethylene （dpe） introduced as a bridging ligand have been synthesized via hydrothermal method and ...Three new Zn（Ⅱ）/Cd（Ⅱ） coordination polymers based on 2-mercaptonicotinic acid （H2mna） with 1,2-di（4-pyridyl）ethylene （dpe） introduced as a bridging ligand have been synthesized via hydrothermal method and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. As reported in this paper, [Zn2（dpe）0.5（mna）2] （1） can be classified as a two-dimensional layer structure in which the 1D chain composed of Zn（Ⅱ） and mna ligands is bridged by dpe ligands, while the complex named [Zn4（dpe）4（mna）4] （2） is a tetra-nuclear cluster compound. These two compounds are further extended to three-dimensional structures by hydrogen bonds along with C–H…π and π…π interactions. Compound 3 with general formular [Cd2（dpe）0.5（mna）2]·H2O belongs to a three-dimensional porous structure in which the 2D metal layers formed by the coordination of Cd（Ⅱ） and mna ligands are connected with the bridging of dpe ligands.展开更多
Polyethylene (PE) grafting 4-vinylpyridine copolymers has been produced as powders of different rushes by theirradiation method. After treatment with methylaluminoxane (MAO), the copolymers were used as supports for C...Polyethylene (PE) grafting 4-vinylpyridine copolymers has been produced as powders of different rushes by theirradiation method. After treatment with methylaluminoxane (MAO), the copolymers were used as supports for Cp_2ZrCl_2catalyst Results of X-ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy, ultraviolet spectroscopy andscanning electron microscope measurements show that the catalytic sites have been linked through MAO on the PE-graft-4-vinylpyridine (PEVP). The percentages of grafting 4-vinylpyridine and supported Cp_2ZrCl_2 depend on the size ofpolyethylene powder. The smaller the polyethylene powder, the more percent of 4-vinylpyridine groups and Cp_2ZrCl_2 existon the polyethylene chains, and the PEVP-supported catalyst has a relatively high activity for ethylene polymerization.展开更多
The regulation of apple(Malus domestica)fruit texture during ripening is complex and a fundamental determinant of its commercial quality.In climacteric fruit,ripening-related processes are regulated by ethylene(ET),an...The regulation of apple(Malus domestica)fruit texture during ripening is complex and a fundamental determinant of its commercial quality.In climacteric fruit,ripening-related processes are regulated by ethylene(ET),and jasmonate(JA)is also involved in the ethylene biosynthesis pathway,mainly through the transcription factor MYC2.However,the molecular genetic mechanism for fruit ripening processes between the JA and ET signaling pathways still needs to be elucidated.In order to explore how JA regulates apple fruit ripening through ERF4,we used’Gala’and’Ralls Janet’fruit at different developmental stages as experimental materials to determine the fruit firmness and related gene expression analysis.Meanwhile,we carried out different hormone treatments on’Gala’fruit at ripening stage.Here,we show that ERF4 is a core JA signaling hub protein JASMONATE ZIM-DOMAIN(JAZ)interactor that affects ethylene signaling pathways.During fruit development,ERF4 represses the expression of ACS1 and ACO1 by interacting with JAZ,as well as with the JA-activated transcription factor MYC2.Ripening is promoted in JAZ-suppressed apples.Thus,ERF4 acts as a molecular link between ethylene and JA hormone signals,and the natural variation of the ERF4Ethylene-responsive binding factor-associated amphiphilic repression(EAR)motif decreases repression of ethylene biosynthesis genes.展开更多
Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse differential reactor. From the performance of the catalysts with differ...Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse differential reactor. From the performance of the catalysts with different compositions and configurations, it is proposed that acetic acid is predominantly produced via an intermediate of acetaldehyde. This can be easily confirmed by comparing the product distributions in the integral and the differential reactors. The active sites for acetic acid formation are considered to exist mainly at the boundaries between the H4SiW12O40 and the Pd particles. The Pd-based catalysts reduced by H2/N2 have higher activities than those reduced by hydrazine, as explained by the degree of Pd dispersion obtained from the characteristics of hydrogen chemical adsorption. It was found that the Pd-Se-SiW12/SiO2 catalyst with selenium tetrachloride as a precursor was more active than that with potassium selenite, and that the acetic acid yield can be greatly increased by adding a suitable amount of dichloroethane (C2H4C12/C2H4 mole ratio=0.03) to the reactants.展开更多
With the decrease of pH value from 8.45 to -1.0, the UV-Vis absorption and fluorescent spectra of 1,2-bis（4-pyridyl） ethylene（BPE） took on the same changing trend at four different successive pH stages： 8.45--7.2...With the decrease of pH value from 8.45 to -1.0, the UV-Vis absorption and fluorescent spectra of 1,2-bis（4-pyridyl） ethylene（BPE） took on the same changing trend at four different successive pH stages： 8.45--7.20, 7.20--5.62, 5.62--2.60, and 2.60--1.0, namely, no change, decrease, increase, and decrease again. Among these, in a range of 7.20--5.62, the fluorescence wavelength blueshifted from 418 to 359 nm, but the UV-Vis absorption wavelength, in contrast, redshifted from 285 to 298 nm. The fluorescence intensity of BPE had a drop even to quench upon a decline in the pH value from 2.60 to -1.0 probably owing to its cation-re interaction to reduce the π electron cloud density of BPE. Two dissociation constants, pKa1（4.30±0.01） and PKa2（5.65±0.04）, were obtained based on fluorescence data. The changes of fluorescence spectra indicate that BPE has ＂oft-on-off＂ switch behavior. The fluorescent spectra of BPE were nearly independent on the presence of α- and β-cyclodextrins.展开更多
Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronico- tinamide (BNAH) in deaerated acetonitrile to give 1, 1-di-p-methoxyphenyl-2, 2-dinitroethane, while 1, 1-di-O-methoxyphenyl-2, 2-dinitroet...Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronico- tinamide (BNAH) in deaerated acetonitrile to give 1, 1-di-p-methoxyphenyl-2, 2-dinitroethane, while 1, 1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism.展开更多
ABSTRACT A simple, economic, and time-efficient related substance, GC method has been developed for the analysis of 1,4-Cyclohexanedione mono- ethylene ketal(will be specified as ketal) in the presence of a potential ...ABSTRACT A simple, economic, and time-efficient related substance, GC method has been developed for the analysis of 1,4-Cyclohexanedione mono- ethylene ketal(will be specified as ketal) in the presence of a potential impurity 1,4-cyclohexa- nedione bis (ethylene ketal) [will be specified as diketal]. Successful chromatographic separa- tion of the ketal from the impurity was achieved on a DBWAX ETR, 30 m x 0.32 mm x 1.0μ FT column with nitrogen as carrier gas and FID detector. The method was validated for linearity, accuracy, precision, and specificity and can be used for quality control during manufacture of ketal. A validated GC method is reported for the ketal for the first time.展开更多
Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3...Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3 ) as the cocatalyst in place of methylaluminoxane (MAO) to catalyze ethylene oligomerization and copolymerization in situ. The influences of procedure for supporting NiL-TiCl 4 , the molar ratio of NiL to TiCl 4 , cocatalyst type and polymerization temperature on the catalytic performance were studied. The degree of branching and the composition of the branched chain of polymers produced have been investigated by IR and 13C-NMR spectra. The results show that the combined catalyst can synthesize the branched polyethylene with various banched chains .The polymerization reaction was monitored by gas chromatography and mass spectrometry (GC-MS). The results show that this catalyst promotes the oligomerization and copolymerization in situ for ethylene.展开更多
An arachidic acid/poly （3, 4-ethylene dioxythiophene） （AA/PEDOT） multilayer Langmuir-Blodgett （LB） film was prepared by a modified LB film method. The theories were utilized to explain the effects between HCl mo...An arachidic acid/poly （3, 4-ethylene dioxythiophene） （AA/PEDOT） multilayer Langmuir-Blodgett （LB） film was prepared by a modified LB film method. The theories were utilized to explain the effects between HCl molecule and LB film. The gas sensitivity mechanism of poly （3, 4-ethylene dioxythiophene） （PEDOT） multilayer film can be explained by the charge transfer between p system of PEDOT and oxidization HCl system. The gas sensitivity of PEDOT LB film deposited interdigital electrode to HCl was tested. The results showed that film thickness, treating temperature, deposition speed had different influence on film gas sensitivity. The AA/PEDOT film deposited device exhibited nonlinear behavior to HCl gas at lower concentration （20-60 ppm） and linear response behavior at higher gas concentration was observed. The time of the compound LB film of the AA/PEDOT responding to the 30 ppm HCl gas is about 20 seconds, which is far quicker than the time of the film to the PEDOTPRESS film（about 80 seconds）. It is not higher film press to better film. When the film press attains 45 mNs/m, the sensitivity of the AA/PEDOT film on the contrary descends.展开更多
As a kind of low-cost and readily available industrial byproduct, ethylene tar （ET） was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin （COPNAR）. The basic pr...As a kind of low-cost and readily available industrial byproduct, ethylene tar （ET） was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin （COPNAR）. The basic properties of ET and the resulted COPNAR were characterized by FT-IR, IH-NMR, TGA and elemental analysis. The test results showed that ET with high aromatic content （〉50%） was suitable for the synthesis of COPNAR with superior heat resistance. The average molecular structure of ET was obtained by means of the improved Brown-Ladner method, and the reaction mechanism was considered as an acid-catalyzed positive ion-typed polymerization. Our findings have provided a new route to develop ET into technology-added heat-resistant resins.展开更多
Poly(ethylene-oxide)(PEO)-based membranes have attracted much attention recently for CO2 separation because CO2 is highly soluble into PEO and shows high selectivity over other gases such as CH4 and N2.Unfortunately,t...Poly(ethylene-oxide)(PEO)-based membranes have attracted much attention recently for CO2 separation because CO2 is highly soluble into PEO and shows high selectivity over other gases such as CH4 and N2.Unfortunately,those membranes are not strong enough mechanically and highly crystalline,which hinders their broader applications for separation membranes.In this review discussions are made,as much in detail as possible,on the strategies to improve gas separation performance of PEO-based membranes.Some of techniques such as synthesis of graft copolymers that contain PEO,cross-linking of polymers and blending with long chains polymers contributed significantly to improvement of membrane.Incorporation of ionic liquids/nanoparticles has also been found effective.However,surface modification of nanoparticles has been done chemically or physically to enhance their compatibility with polymer matrix.As a result of all such efforts,an excellent performance,i.e.,CO2 permeability up to 200 Barrer,CO2/N2 selectivity up to 200 and CO2/CH4 selectivity up to 70,could be achieved.Another method is to introduce functional groups into PEO-based polymers which boosted CO2 permeability up to 200 Barrer with CO2/CH4 selectivity between 40 and 50.The CO2 permeability of PEO-based membranes increases,without much change in selectivity,when the length of ethylene oxide is increased.展开更多
AIM: To investigate the growth effects of 4-phenyl butyric acid (PBA) on human gastric carcinoma cells and their mechanisms. METHODS: Moderately-differentiated human gastric carcinoma SGC-7901 and lowly-differentiated...AIM: To investigate the growth effects of 4-phenyl butyric acid (PBA) on human gastric carcinoma cells and their mechanisms. METHODS: Moderately-differentiated human gastric carcinoma SGC-7901 and lowly-differentiated MGC-803 cells were treated with 5, 10, 20, 40, and 60 μmol/L PBA for 1-4 d. Cell proliferation was detected using the MTT colorimetric assay. Cell cycle distributions were examined using flow cytometry.RESULTS: The proliferation of gastric carcinoma cells was inhibited by PBA in a doseand time-dependent fashion. Flow cytometry showed that SGC-7901 cells treated with low concentrations of PBA were arrested at the G0/G1 phase, whereas cells treated with high concentrations of PBA were arrested at the G2/M phase. Although MGC-803 cells treated with low concentrations of PBA were also arrested at the G0/G1 phase, cells treated with high concentrations of PBA were arrested at the S phase. CONCLUSION: The growth inhibitory effect of PBA on gastric cancer cells is associated with alteration of the cell cycle. For moderately-differentiated gastric cancer cells, the cell cycle was arrested at the G0/G1 and G2/M phases. For lowly-differentiated gastric cancer cells, the cell cycle was arrested at the G0/G1 and S phases.展开更多
A two-dimensional lead complex, [Pb（C14N3O2H12S）（NO3）]n·nH2O, was prepared by the reaction of salicylyl-4-phenyl thiosemicarbazide and lead nitrate. The compound （C14H13N4O6PbS, Mr = 572.53） crystallizes in...A two-dimensional lead complex, [Pb（C14N3O2H12S）（NO3）]n·nH2O, was prepared by the reaction of salicylyl-4-phenyl thiosemicarbazide and lead nitrate. The compound （C14H13N4O6PbS, Mr = 572.53） crystallizes in the monoclinic space group P21/c with a = 11.2984（2）, b = 15.6628（7）, c = 11.1118（2）A,β= 113.564（2）°, V = 1802.43（10）A3, Dc= 2.110 g/cm3, Z = 4,μt（MoKα） = 9.515 mm-1, F（000） = 1084, the final R = 0.0394 and wR = 0.0701 for 2552 observed reflections with I 〉 2σ（I）. The Pb（Ⅱ） ion displays a distorted octahedron in which the hypothesized stereochemically active lone pair occupies the apex. The compound exhibits a two-dimensional network structure formed by the zigzag one-dimensional chains joined by two μ-O of two nitrate groups in overlapping. A large ring exists in the two-dimensional layers. The TGA of the title compound has been studied.展开更多
基金support of National Natural Science Foundation of China(22179027)gratefully acknowledged.This work was also supported by the Natural Science Foundation of Guangxi Province(2021GXNSFAA075063,2018GXNSFDA281005)+1 种基金the National Key Research and Development Program of China(2017YFE0105500)Science&Technology Research Project of Guangdong Province(2017A020216009).
文摘Chemical-looping oxidative dehydrogenation(CL-ODH)is a process designed for the conversion of alkanes into olefins through cyclic redox reactions,eliminating the need for gaseous O_(2).In this work,we investigated the use of Ca_(2)MnO_(4)-layered perovskites modified with NaNO_(3) dopants,serving as redox catalysts(also known as oxygen carriers),for the CL-ODH of ethane within a temperature range of 700-780℃.Our findings revealed that the incorporation of NaNO_(3) as a modifier significantly-nhanced the selectivity for-thylene generation from Ca_(2)MnO_(4).At 750℃and a gas hourly space velocity of 1300 h^(-1),we achieved an-thane conversion up to 68.17%,accompanied by a corresponding-thylene yield of 57.39%.X-ray photoelectron spectroscopy analysis unveiled that the doping NaNO_(3) onto Ca_(2)MnO_(4) not only played a role in reducing the oxidation state of Mn ions but also increased the lattice oxygen content of the redox catalyst.Furthermore,formation of NaNO_(3) shell on the surface of Ca_(2)MnO_(4) led to a reduction in the concentration of manganese sites and modulated the oxygen-releasing behavior in a step-wise manner.This modulation contributed significantly to the enhanced selectivity for ethylene of the NaNO_(3)-doped Ca_(2)MnO_(4) catalyst.These findings provide compelling evidence for the potential of Ca_(2)MnO_(4)-layered perovskites as promising redox catalysts in the context of CL-ODH reactions.
基金supported by the National Natural Science Foundation of China(52172201,51732005,51902118,and 52102249)the China Postdoctoral Science Foundation(2019M662609and 2020T130217)for financial support。
文摘Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.EC is also the most widely used electrolyte solvent in sodium ion batteries.However,compared to lithium metal,sodium metal(Na)shows higher activity and reacts violently with EC-based electrolyte(NaPF_(6)as solute),which leads to the failure of sodium metal batteries(SMBs).Herein,we reveal the electrochemical instability mechanism of EC on sodium metal battery,and find that the com-bination of EC and NaPF_(6) is electrically reduced in sodium metal anode during charging,resulting in the reduction of the first coulombic efficiency,and the continuous consumption of electrolyte leads to the cell failure.To address the above issues,an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes.Specifically,ethyl methyl carbonate(EMC)and dimethyl carbon-ate(DMC)as solvents and fluoroethylene carbonate(FEC)as SEI-forming additive have been identified as the optimal solvent for NaFP_(6)based electrolyte and used in Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))/Na batteries.The batter-ies exhibit excellent capacity retention rate of about 80%over 1000 cycles at a cut-off voltage of 4.3 V.
基金supported by grants from the 973 Program(2012CB821702)the National Natural Science Foundation of China(21073192,21173223 and 21173220)the Science Foundation of CAS(KJCX2-YW-H20)and of Fujian Province(2009HZ0006-1)
文摘Three new Zn（Ⅱ）/Cd（Ⅱ） coordination polymers based on 2-mercaptonicotinic acid （H2mna） with 1,2-di（4-pyridyl）ethylene （dpe） introduced as a bridging ligand have been synthesized via hydrothermal method and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. As reported in this paper, [Zn2（dpe）0.5（mna）2] （1） can be classified as a two-dimensional layer structure in which the 1D chain composed of Zn（Ⅱ） and mna ligands is bridged by dpe ligands, while the complex named [Zn4（dpe）4（mna）4] （2） is a tetra-nuclear cluster compound. These two compounds are further extended to three-dimensional structures by hydrogen bonds along with C–H…π and π…π interactions. Compound 3 with general formular [Cd2（dpe）0.5（mna）2]·H2O belongs to a three-dimensional porous structure in which the 2D metal layers formed by the coordination of Cd（Ⅱ） and mna ligands are connected with the bridging of dpe ligands.
基金National Natural Science Foundation of China (No. 20272062)
文摘Polyethylene (PE) grafting 4-vinylpyridine copolymers has been produced as powders of different rushes by theirradiation method. After treatment with methylaluminoxane (MAO), the copolymers were used as supports for Cp_2ZrCl_2catalyst Results of X-ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy, ultraviolet spectroscopy andscanning electron microscope measurements show that the catalytic sites have been linked through MAO on the PE-graft-4-vinylpyridine (PEVP). The percentages of grafting 4-vinylpyridine and supported Cp_2ZrCl_2 depend on the size ofpolyethylene powder. The smaller the polyethylene powder, the more percent of 4-vinylpyridine groups and Cp_2ZrCl_2 existon the polyethylene chains, and the PEVP-supported catalyst has a relatively high activity for ethylene polymerization.
基金supported by the National Key Research and Development Program [Grant No.2018YFD1000200]the National Natural Science Foundation of China [Grant Nos.31872941,32072543]+2 种基金the Construction of Beijing Science and Technology Innovation and Service Capacity in Top Subjects [Grant No.CEFFPXM2019_014207_000032]the 111 Project [Grant No.B17043]the Engineering Research Center of Breeding and Propagation of Horticultural Crops,Ministry of Education。
文摘The regulation of apple(Malus domestica)fruit texture during ripening is complex and a fundamental determinant of its commercial quality.In climacteric fruit,ripening-related processes are regulated by ethylene(ET),and jasmonate(JA)is also involved in the ethylene biosynthesis pathway,mainly through the transcription factor MYC2.However,the molecular genetic mechanism for fruit ripening processes between the JA and ET signaling pathways still needs to be elucidated.In order to explore how JA regulates apple fruit ripening through ERF4,we used’Gala’and’Ralls Janet’fruit at different developmental stages as experimental materials to determine the fruit firmness and related gene expression analysis.Meanwhile,we carried out different hormone treatments on’Gala’fruit at ripening stage.Here,we show that ERF4 is a core JA signaling hub protein JASMONATE ZIM-DOMAIN(JAZ)interactor that affects ethylene signaling pathways.During fruit development,ERF4 represses the expression of ACS1 and ACO1 by interacting with JAZ,as well as with the JA-activated transcription factor MYC2.Ripening is promoted in JAZ-suppressed apples.Thus,ERF4 acts as a molecular link between ethylene and JA hormone signals,and the natural variation of the ERF4Ethylene-responsive binding factor-associated amphiphilic repression(EAR)motif decreases repression of ethylene biosynthesis genes.
文摘Synthesis of acetic acid by direct oxidation of ethylene on Pd-H4SiW12O40-based catalysts was studied in a fixed-bed integral reactor and a pulse differential reactor. From the performance of the catalysts with different compositions and configurations, it is proposed that acetic acid is predominantly produced via an intermediate of acetaldehyde. This can be easily confirmed by comparing the product distributions in the integral and the differential reactors. The active sites for acetic acid formation are considered to exist mainly at the boundaries between the H4SiW12O40 and the Pd particles. The Pd-based catalysts reduced by H2/N2 have higher activities than those reduced by hydrazine, as explained by the degree of Pd dispersion obtained from the characteristics of hydrogen chemical adsorption. It was found that the Pd-Se-SiW12/SiO2 catalyst with selenium tetrachloride as a precursor was more active than that with potassium selenite, and that the acetic acid yield can be greatly increased by adding a suitable amount of dichloroethane (C2H4C12/C2H4 mole ratio=0.03) to the reactants.
基金Supported by the National Natural Science Foundation of China(No.20675009)
文摘With the decrease of pH value from 8.45 to -1.0, the UV-Vis absorption and fluorescent spectra of 1,2-bis（4-pyridyl） ethylene（BPE） took on the same changing trend at four different successive pH stages： 8.45--7.20, 7.20--5.62, 5.62--2.60, and 2.60--1.0, namely, no change, decrease, increase, and decrease again. Among these, in a range of 7.20--5.62, the fluorescence wavelength blueshifted from 418 to 359 nm, but the UV-Vis absorption wavelength, in contrast, redshifted from 285 to 298 nm. The fluorescence intensity of BPE had a drop even to quench upon a decline in the pH value from 2.60 to -1.0 probably owing to its cation-re interaction to reduce the π electron cloud density of BPE. Two dissociation constants, pKa1（4.30±0.01） and PKa2（5.65±0.04）, were obtained based on fluorescence data. The changes of fluorescence spectra indicate that BPE has ＂oft-on-off＂ switch behavior. The fluorescent spectra of BPE were nearly independent on the presence of α- and β-cyclodextrins.
文摘Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronico- tinamide (BNAH) in deaerated acetonitrile to give 1, 1-di-p-methoxyphenyl-2, 2-dinitroethane, while 1, 1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism.
文摘ABSTRACT A simple, economic, and time-efficient related substance, GC method has been developed for the analysis of 1,4-Cyclohexanedione mono- ethylene ketal(will be specified as ketal) in the presence of a potential impurity 1,4-cyclohexa- nedione bis (ethylene ketal) [will be specified as diketal]. Successful chromatographic separa- tion of the ketal from the impurity was achieved on a DBWAX ETR, 30 m x 0.32 mm x 1.0μ FT column with nitrogen as carrier gas and FID detector. The method was validated for linearity, accuracy, precision, and specificity and can be used for quality control during manufacture of ketal. A validated GC method is reported for the ketal for the first time.
基金This project was supported by the National Natural Science Foundation of China (No. 29874039) and the Foundation ofGuangdong Province (No. 031598).
文摘Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3 ) as the cocatalyst in place of methylaluminoxane (MAO) to catalyze ethylene oligomerization and copolymerization in situ. The influences of procedure for supporting NiL-TiCl 4 , the molar ratio of NiL to TiCl 4 , cocatalyst type and polymerization temperature on the catalytic performance were studied. The degree of branching and the composition of the branched chain of polymers produced have been investigated by IR and 13C-NMR spectra. The results show that the combined catalyst can synthesize the branched polyethylene with various banched chains .The polymerization reaction was monitored by gas chromatography and mass spectrometry (GC-MS). The results show that this catalyst promotes the oligomerization and copolymerization in situ for ethylene.
基金Supported by the National Key Project of Fundamental Research( G2 0 0 0 0 7810 2 ) and the National Natural ScienceFoundation of China( No. 2 9992 5 90 - 5 )
基金Funded by the National Natural Science Foundation of China (No.60372002)
文摘An arachidic acid/poly （3, 4-ethylene dioxythiophene） （AA/PEDOT） multilayer Langmuir-Blodgett （LB） film was prepared by a modified LB film method. The theories were utilized to explain the effects between HCl molecule and LB film. The gas sensitivity mechanism of poly （3, 4-ethylene dioxythiophene） （PEDOT） multilayer film can be explained by the charge transfer between p system of PEDOT and oxidization HCl system. The gas sensitivity of PEDOT LB film deposited interdigital electrode to HCl was tested. The results showed that film thickness, treating temperature, deposition speed had different influence on film gas sensitivity. The AA/PEDOT film deposited device exhibited nonlinear behavior to HCl gas at lower concentration （20-60 ppm） and linear response behavior at higher gas concentration was observed. The time of the compound LB film of the AA/PEDOT responding to the 30 ppm HCl gas is about 20 seconds, which is far quicker than the time of the film to the PEDOTPRESS film（about 80 seconds）. It is not higher film press to better film. When the film press attains 45 mNs/m, the sensitivity of the AA/PEDOT film on the contrary descends.
基金supported by the Program for New Century Excellent Talents in University, China Ministry of Education, 2009 (No. NCET-10-0768)the National Natural Science Foundation of China (Nos. 20876176 and 51172285)the Natural Science Foundation of Shandong Province (ZR2011EL031, ZR2011EL030)
文摘As a kind of low-cost and readily available industrial byproduct, ethylene tar （ET） was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin （COPNAR）. The basic properties of ET and the resulted COPNAR were characterized by FT-IR, IH-NMR, TGA and elemental analysis. The test results showed that ET with high aromatic content （〉50%） was suitable for the synthesis of COPNAR with superior heat resistance. The average molecular structure of ET was obtained by means of the improved Brown-Ladner method, and the reaction mechanism was considered as an acid-catalyzed positive ion-typed polymerization. Our findings have provided a new route to develop ET into technology-added heat-resistant resins.
文摘Poly(ethylene-oxide)(PEO)-based membranes have attracted much attention recently for CO2 separation because CO2 is highly soluble into PEO and shows high selectivity over other gases such as CH4 and N2.Unfortunately,those membranes are not strong enough mechanically and highly crystalline,which hinders their broader applications for separation membranes.In this review discussions are made,as much in detail as possible,on the strategies to improve gas separation performance of PEO-based membranes.Some of techniques such as synthesis of graft copolymers that contain PEO,cross-linking of polymers and blending with long chains polymers contributed significantly to improvement of membrane.Incorporation of ionic liquids/nanoparticles has also been found effective.However,surface modification of nanoparticles has been done chemically or physically to enhance their compatibility with polymer matrix.As a result of all such efforts,an excellent performance,i.e.,CO2 permeability up to 200 Barrer,CO2/N2 selectivity up to 200 and CO2/CH4 selectivity up to 70,could be achieved.Another method is to introduce functional groups into PEO-based polymers which boosted CO2 permeability up to 200 Barrer with CO2/CH4 selectivity between 40 and 50.The CO2 permeability of PEO-based membranes increases,without much change in selectivity,when the length of ethylene oxide is increased.
基金Supported by Natural Science Foundation of Ningbo, No. 2009A610134Natural Sciences Foundation of Zhejiang, No. Y207244+3 种基金College Students’ Science-Technology Innovation Program of Zhejiang Province, No. 200959the Excellent Disser-tation Foundation of Ningbo University, No. 201014KC Wong Magna Fund of Ningbo Universitythe Scientific Innovation Team Project of Ningbo, No.2011B82014
文摘AIM: To investigate the growth effects of 4-phenyl butyric acid (PBA) on human gastric carcinoma cells and their mechanisms. METHODS: Moderately-differentiated human gastric carcinoma SGC-7901 and lowly-differentiated MGC-803 cells were treated with 5, 10, 20, 40, and 60 μmol/L PBA for 1-4 d. Cell proliferation was detected using the MTT colorimetric assay. Cell cycle distributions were examined using flow cytometry.RESULTS: The proliferation of gastric carcinoma cells was inhibited by PBA in a doseand time-dependent fashion. Flow cytometry showed that SGC-7901 cells treated with low concentrations of PBA were arrested at the G0/G1 phase, whereas cells treated with high concentrations of PBA were arrested at the G2/M phase. Although MGC-803 cells treated with low concentrations of PBA were also arrested at the G0/G1 phase, cells treated with high concentrations of PBA were arrested at the S phase. CONCLUSION: The growth inhibitory effect of PBA on gastric cancer cells is associated with alteration of the cell cycle. For moderately-differentiated gastric cancer cells, the cell cycle was arrested at the G0/G1 and G2/M phases. For lowly-differentiated gastric cancer cells, the cell cycle was arrested at the G0/G1 and S phases.
基金supported by the Science Foundation of Huaqiao University (07BS509)
文摘A two-dimensional lead complex, [Pb（C14N3O2H12S）（NO3）]n·nH2O, was prepared by the reaction of salicylyl-4-phenyl thiosemicarbazide and lead nitrate. The compound （C14H13N4O6PbS, Mr = 572.53） crystallizes in the monoclinic space group P21/c with a = 11.2984（2）, b = 15.6628（7）, c = 11.1118（2）A,β= 113.564（2）°, V = 1802.43（10）A3, Dc= 2.110 g/cm3, Z = 4,μt（MoKα） = 9.515 mm-1, F（000） = 1084, the final R = 0.0394 and wR = 0.0701 for 2552 observed reflections with I 〉 2σ（I）. The Pb（Ⅱ） ion displays a distorted octahedron in which the hypothesized stereochemically active lone pair occupies the apex. The compound exhibits a two-dimensional network structure formed by the zigzag one-dimensional chains joined by two μ-O of two nitrate groups in overlapping. A large ring exists in the two-dimensional layers. The TGA of the title compound has been studied.
