In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_...In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.展开更多
A new six-membered cyclic carbonate monomer, 5-allyloxytrimethylene carbonate （ATMC）, was synthesized starting from glycerol, and the corresponding polycarbonates, poly（5-allyloxytrimethylene carbonate）（PATMC） w...A new six-membered cyclic carbonate monomer, 5-allyloxytrimethylene carbonate （ATMC）, was synthesized starting from glycerol, and the corresponding polycarbonates, poly（5-allyloxytrimethylene carbonate）（PATMC） were further synthesized by ring-opening polymerization in bulk at 150℃ using stannous octanoate as an initiator. The structures of the monomer and the polymers were confirmed by IR, IH-NMR, 13C-NMR, and GPC analysis.展开更多
The ring opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by single component of tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanide (Ln(OAr)(3)) is reported. The initiators are highly activ...The ring opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by single component of tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanide (Ln(OAr)(3)) is reported. The initiators are highly active to the polymerization and give high molecular weight polymers. (HNMR)-H-1 spectra and DSC measurement suggest the polymerization is free of decarboxylation. Mechanism study shows that the monomer insertion is via the break of acyl-oxygen bond of DTC.展开更多
Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were ...Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.展开更多
In this paper,we study the biological response induced by heavy ions irradiation of high dose,human peripheral blood lymphocytes are irradiated in vitro by the carbon ions of LET=35 keV/μm,and the chromosome aberrati...In this paper,we study the biological response induced by heavy ions irradiation of high dose,human peripheral blood lymphocytes are irradiated in vitro by the carbon ions of LET=35 keV/μm,and the chromosome aberrations at absorbed doses of 0-20 Gy are analyzed by the calyculin A-induced premature chromosome condensation(PCC).The frequencies of PCC-rings at the stage of G2/M-phase increase steeply with radiation doses up to 20 Gy at a rate of 0.017 Gy^(-1).The G2-PCC index remains more than 5%up to 15 Gy,and 3%after 20 Gy,this is high enough to score a substantial number of chromosome spreads without dose-rate effect.The results show that the calyculin A-induced PCC technique is suitable for analyzing the chromosome damage induced by carbon ions irradiation of high dose.展开更多
In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube ...In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube （CNT） ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thor- oughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materi- als, and hold potential for enhancing their mechanical, chemical, optical and electronic properties.展开更多
Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate （BTMC） with poly （vinyl pyrrolidone） （PVP） was successfully synthesized using immobilized porcine pancreas lipase （IPPL） or SnOct2 as catalyst. Hydrox...Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate （BTMC） with poly （vinyl pyrrolidone） （PVP） was successfully synthesized using immobilized porcine pancreas lipase （IPPL） or SnOct2 as catalyst. Hydroxyl terminated PVP, synthesized with 2-mercaptoethanol as a chain transfer reagent, was employed as a rnacroinitiator. The resulting copolymers were characterized by GPC, ^1H NMR and IR. Increasing the BTMC/PVP-OH feed ratio （[B]/[P]） resulted in the increase of Mn of corresponding copolymers and the decrease of Mw/Mn. Immobilized enzyme has comparable catalytic activity to SnOct2 for the copolymerization.展开更多
Relationship between the δ 13C of tree ring cellulose from Pinus Koraiensis and climate parameters was investigated. A significantly negative correlation between δ 13C and mean low-cloud amount from May to July was ...Relationship between the δ 13C of tree ring cellulose from Pinus Koraiensis and climate parameters was investigated. A significantly negative correlation between δ 13C and mean low-cloud amount from May to July was discovered, which contributes to reconstructing the mean low-cloud amount from May to July at Antu in recent 200 years. Periodicals of quasi-8-year, quasi-4-year and quasi-2-year were detected both in δ 13C series and in the reconstructed low cloud amount series with 95% confidence level. Quasi-8-year period may reflect the integrated influence of solar activity, monsoon activity and local regional factors. Quasi-4-year and quasi-2-year periods indicate the influences of ENSO and Quasi Biennial Oscillation (QBO) of East Asian monsoon, respectively.展开更多
Stable isotopes in tree-ring cellulose provide important data in ecological,archaeological,and paleoenvironmental researches,thereby,the demand for stable isotope analyses is increasing rapidly.Simultaneous measuremen...Stable isotopes in tree-ring cellulose provide important data in ecological,archaeological,and paleoenvironmental researches,thereby,the demand for stable isotope analyses is increasing rapidly.Simultaneous measurement of cellulose δC and δO values from tree rings would reduce the cost of isotopic commodities and improve the analytical efficiency compared with conventional separate measurement.In this study,we compared the δC and δO values of tree-ringα-cellulose from Tianshan spruce(Picea schrenkiana)in an arid site in the drainage basin of the Urumqi River in Xinjiang of northwestern China based on separate and simultaneous measurements,using the combustion method(at1050°C)and the high-temperature pyrolysis method(at 1350°C and 1400°C).We verified the results of simultaneous measurement using the outputs from separate measurement and found that both methods(separate and simultaneous)produced similar δC values.The two-point calibrated method improved the results(range and variation)of δC and δO values.The mean values,standard deviations,and trends of the tree-ring δC obtained by the combustion method were similar to those by the pyrolysis method followed by two-point calibration.The simultaneously measured δO from the pyrolysis method at 1400°C had a nearly constant offset with that the pyrolysis method at 1350°C due to isotopic-dependence on the reaction temperature.However,they showed similar variations in the time series.The climate responses inferred from simultaneously and separately measured δC and δO did not differ between the two methods.The tree-ring δC and δO values were negatively correlated with standardized precipitation evapotranspiration index from May to August.In addition,the δO was significantly correlated with temperature(positive),precipitation(negative),and relative humidity(negative)from May to August.The tree-ring δC and δO values determined simultaneously through the high-temperature pyrolysis method could produce acceptable and reliable stable isotope series.The simultaneous isotopic measurement can greatly reduce the cost and time requirement compared with the separate isotopic measurement.These results are consistent with the previous studies at humid sites,suggesting that the simultaneous determination of δC and δO in tree-ringα-cellulose can be used in wide regions.展开更多
基金This work was financially supported by the Special Fund for Major State Basic Research Project(G1999064801)the National Natural Science Foundation of China(Nos.20174033 and 20434020)
文摘In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.
基金support of the National Natural Science Foundation of China(Grant No.20104005)
文摘A new six-membered cyclic carbonate monomer, 5-allyloxytrimethylene carbonate （ATMC）, was synthesized starting from glycerol, and the corresponding polycarbonates, poly（5-allyloxytrimethylene carbonate）（PATMC） were further synthesized by ring-opening polymerization in bulk at 150℃ using stannous octanoate as an initiator. The structures of the monomer and the polymers were confirmed by IR, IH-NMR, 13C-NMR, and GPC analysis.
文摘The ring opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by single component of tris(2,6-di-tert-butyl-4-methylphenoxo) lanthanide (Ln(OAr)(3)) is reported. The initiators are highly active to the polymerization and give high molecular weight polymers. (HNMR)-H-1 spectra and DSC measurement suggest the polymerization is free of decarboxylation. Mechanism study shows that the monomer insertion is via the break of acyl-oxygen bond of DTC.
基金This work was supported by the National Natural Science Foundation of China (No. 29674027, No. 29844002), the Ministry of National Education (G98402) and Organometallic Laboratory of Institute of Organic Chemistry of Chinese Academy of Sciences.
文摘Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalyst has been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated in detail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and gives high molecular weight (M-v = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd (molar ratio) = 2,000, 80 degrees C, 16 h. The polymers were characterized by NMR, GPC and DSC. Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.
基金Supported by National Natural Science Foundation of China(10875153)The President Scholarship of Chinese Academy of Sciences for Postgraduate students (O906350YZ0)The Talent Training Program for PhD in West China of the Chinese Academy of Sciences(O806260XB0,and O806270XBB)
文摘In this paper,we study the biological response induced by heavy ions irradiation of high dose,human peripheral blood lymphocytes are irradiated in vitro by the carbon ions of LET=35 keV/μm,and the chromosome aberrations at absorbed doses of 0-20 Gy are analyzed by the calyculin A-induced premature chromosome condensation(PCC).The frequencies of PCC-rings at the stage of G2/M-phase increase steeply with radiation doses up to 20 Gy at a rate of 0.017 Gy^(-1).The G2-PCC index remains more than 5%up to 15 Gy,and 3%after 20 Gy,this is high enough to score a substantial number of chromosome spreads without dose-rate effect.The results show that the calyculin A-induced PCC technique is suitable for analyzing the chromosome damage induced by carbon ions irradiation of high dose.
基金supported by the National Natural Science Foundation of China (11272357 and 11102140)Doctoral Fund of Ministry of Education of China (200804251520 and 20110141120024)Natural Science Foundation of Shandong Province (ZR2009AQ006)
文摘In this study, we developed a general method to analytically tackle a kind of movable boundary problem from the viewpoint of energy variation. Having grouped the adhesion of a micro-beam, droplet and carbon nanotube （CNT） ring on a substrate into one framework, we used the developed line of reasoning to investigate the adhesion behaviors of these systems. Based upon the derived governing equations and transversality conditions, explicit solutions involving the critical parameters and morphologies for the three systems are successfully obtained, and then the parameter analogies and common characteristics of them are thor- oughly investigated. The presented method has been verified via the concept of energy release rate in fracture mechanics. Our analyses provide a new approach for exploring the mechanism of different systems with similarities as well as for understanding the unity of nature. The analysis results may be beneficial for the design of nano-structured materi- als, and hold potential for enhancing their mechanical, chemical, optical and electronic properties.
基金the financial support of National Key Fundamental Research Program of China （Grant No. G1999064703） the National Natural Science Foundation of China （Grant No. 20104005）.
文摘Amphiphilic copolymer of 5-benzyloxytrimethylene carbonate （BTMC） with poly （vinyl pyrrolidone） （PVP） was successfully synthesized using immobilized porcine pancreas lipase （IPPL） or SnOct2 as catalyst. Hydroxyl terminated PVP, synthesized with 2-mercaptoethanol as a chain transfer reagent, was employed as a rnacroinitiator. The resulting copolymers were characterized by GPC, ^1H NMR and IR. Increasing the BTMC/PVP-OH feed ratio （[B]/[P]） resulted in the increase of Mn of corresponding copolymers and the decrease of Mw/Mn. Immobilized enzyme has comparable catalytic activity to SnOct2 for the copolymerization.
文摘Relationship between the δ 13C of tree ring cellulose from Pinus Koraiensis and climate parameters was investigated. A significantly negative correlation between δ 13C and mean low-cloud amount from May to July was discovered, which contributes to reconstructing the mean low-cloud amount from May to July at Antu in recent 200 years. Periodicals of quasi-8-year, quasi-4-year and quasi-2-year were detected both in δ 13C series and in the reconstructed low cloud amount series with 95% confidence level. Quasi-8-year period may reflect the integrated influence of solar activity, monsoon activity and local regional factors. Quasi-4-year and quasi-2-year periods indicate the influences of ENSO and Quasi Biennial Oscillation (QBO) of East Asian monsoon, respectively.
基金funded by the National Natural Science Foundation of China (41501049, 41571196)the Self-determination Project of the State Key Laboratory of Cryospheric Sciences (SKLCS-ZZ-2018)+3 种基金the "Light of West China" Program of the Chinese Academy of Sciencesthe Youth Innovation Promotion Association, Chinese Academy of Sciences (2016372)the Chinese Scholarship Council (201704910171)the Fundamental Research Funds for the Central Universities (GK201801007)
文摘Stable isotopes in tree-ring cellulose provide important data in ecological,archaeological,and paleoenvironmental researches,thereby,the demand for stable isotope analyses is increasing rapidly.Simultaneous measurement of cellulose δC and δO values from tree rings would reduce the cost of isotopic commodities and improve the analytical efficiency compared with conventional separate measurement.In this study,we compared the δC and δO values of tree-ringα-cellulose from Tianshan spruce(Picea schrenkiana)in an arid site in the drainage basin of the Urumqi River in Xinjiang of northwestern China based on separate and simultaneous measurements,using the combustion method(at1050°C)and the high-temperature pyrolysis method(at 1350°C and 1400°C).We verified the results of simultaneous measurement using the outputs from separate measurement and found that both methods(separate and simultaneous)produced similar δC values.The two-point calibrated method improved the results(range and variation)of δC and δO values.The mean values,standard deviations,and trends of the tree-ring δC obtained by the combustion method were similar to those by the pyrolysis method followed by two-point calibration.The simultaneously measured δO from the pyrolysis method at 1400°C had a nearly constant offset with that the pyrolysis method at 1350°C due to isotopic-dependence on the reaction temperature.However,they showed similar variations in the time series.The climate responses inferred from simultaneously and separately measured δC and δO did not differ between the two methods.The tree-ring δC and δO values were negatively correlated with standardized precipitation evapotranspiration index from May to August.In addition,the δO was significantly correlated with temperature(positive),precipitation(negative),and relative humidity(negative)from May to August.The tree-ring δC and δO values determined simultaneously through the high-temperature pyrolysis method could produce acceptable and reliable stable isotope series.The simultaneous isotopic measurement can greatly reduce the cost and time requirement compared with the separate isotopic measurement.These results are consistent with the previous studies at humid sites,suggesting that the simultaneous determination of δC and δO in tree-ringα-cellulose can be used in wide regions.
