Synthesis of fourteen new complexes of meso-tetrakis（4-alkoxyphenyl） porphyrins with Co2+, Cu2+, Zn2+, Pb2+ were presented in this paper. Meso-tetrakis （4-alkoxyphenyl） porphyrins were prepared by condensation of ...Synthesis of fourteen new complexes of meso-tetrakis（4-alkoxyphenyl） porphyrins with Co2+, Cu2+, Zn2+, Pb2+ were presented in this paper. Meso-tetrakis （4-alkoxyphenyl） porphyrins were prepared by condensation of 4-alkoxybenzaldehydes with pyrrole, then treated with corresponding metallic acetate to produce mentioned complexes, IR, UV, 1H NMR, MS and elementary analysis were explored to confirm the structures of all theses new complexes. Characteristic spectrometric data of IR, UV, 1H NMR related to these complexes have been systematically summarized. Ten of the fourteen complexes were found to exhibit liquid crystal properties.展开更多
Two new ent-kauranoids, tenuifolin A (3beta,6alpha, 15beta-trihydroxy-1alpha, 7beta-diacetoxy-11beta, 16beta-epoxy-ent-kaurane) (1) and tenuifolin B (1alpha,6alpha, 11beta-trihydroxy-3beta,7beta-diacetoxy-ent-kaur-16-...Two new ent-kauranoids, tenuifolin A (3beta,6alpha, 15beta-trihydroxy-1alpha, 7beta-diacetoxy-11beta, 16beta-epoxy-ent-kaurane) (1) and tenuifolin B (1alpha,6alpha, 11beta-trihydroxy-3beta,7beta-diacetoxy-ent-kaur-16-en-15-one) (2), together with four known compounds were isolated from the aerial parts of Isodon tenuifolia (W. W. Smith) Kudo collected from Zhongdian County, Yunnan Province, China. Their structures were determined by the spectral methods (including 2D NMR techniques).展开更多
A comparative analysis of the codon usage bias was conducted in Methanosarcina mazei str. Goel and two related Euryarchaeota microorganisms （Picrophilus torridus str. DSM 9790 and Natronomonas pharaonis str. DSM 2160...A comparative analysis of the codon usage bias was conducted in Methanosarcina mazei str. Goel and two related Euryarchaeota microorganisms （Picrophilus torridus str. DSM 9790 and Natronomonas pharaonis str. DSM 2160）. Results revealed that synonymous codon usage in Methanosarcina mazei str. Goel was less biased, which was highly correlated with the GC3S value. And the codon usage patterns were phylogenetically conserved among those Euryarchaeota microorganisms. By employing a hierarchical clustering analysis, it can be seen that it is more the species than the gene function that determines their gene codon usage pattems. Considering that those microorganisms live in different environments where the pH conditions vary quite a lot, it can be presumed that their living environments, especially the pH conditions, play an important role in determining those microorganisms＇ codon usage pattems.展开更多
fragments, F- and Cl- including two isotope species 35Cl- and 37Cl-, are observed in the photoexcitations of CFC13. The ion-pair anion efficiency spectra of 35Cl- and 37Cl- are recorded in the photon energy range of 7...fragments, F- and Cl- including two isotope species 35Cl- and 37Cl-, are observed in the photoexcitations of CFC13. The ion-pair anion efficiency spectra of 35Cl- and 37Cl- are recorded in the photon energy range of 7.75-22.00 eV. The threshold of ion-pair dissociation CFCl3-CFC12＋＋Cl- is experimentally determined to be 7.944-0.04 eV. With the references of the high-resolution photoabsorption spectra reported in the literatures, we make tentative assignments of the electron valence-to-Rydberg transitions. Furthermore, the multibody ion-pair fragmentation processes to Cl- are discussed by comparison between the calculated thermochemical thresholds and the experimental efficiency spectrum.展开更多
Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these d...Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these data, the excess molar volume and deviations in viscosity have been calculated. The computed quantities have been fitted to the Redlich-Kister Equation to derive coefficients and estimate the standard error values. Results are discussed in terms of intermolecular interactions.展开更多
Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of th...Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of the temperature on its composition of pyrolysates.At 400℃,pyrolysis of molecular chain could occur,only 13 pyrolysates could be identified.The trimethylene moieties bound to the macromolecular core by ester bonds are cleaved at around 400℃.At 550℃-750℃,pyrolysis of molecular chain could completely take place,46 pyrolysates could be found.As the temperature increases,the compositions of pyrolysate are distinctly increased.Several compounds,especially benzoic acid,monopropenyl-p-phthalate,2-propenyl benzoate,di-2-propenyl ester,1,4-benzenedicarboxylic acid,benzene,1,5-hexadiene,biphenyl and 1,3-propanediol dibenzoate could be formed.The thermal degradation mechanism,which is determined by structure and amount of the thermal decomposition products,are described.During pyrolysis of polytrimethylene terephthalate,polymeric chain scissions take place a peeling reaction as a successive removal of the dimer units from the polymeric chain.The chain scissions are followed by the elimination reaction,linkage action and secondary reactions,which bring about a variety fragment.展开更多
Asymmetric hydrisilylation catalyzed by polymeric thiazolidine rhodium catalystswas conducted. Almost the same optical yields have been obtained when comb-shapedpolymeric ligands and their corresponding monomer comple...Asymmetric hydrisilylation catalyzed by polymeric thiazolidine rhodium catalystswas conducted. Almost the same optical yields have been obtained when comb-shapedpolymeric ligands and their corresponding monomer complexed rhodium cataltystswere used to asymmetric hydrosilylation of acetophenone. Optical yield of chira 1- methylbenzyl alcohol reaches as high as 71.5%. Temperature dependence of enantio- selective hydrosilylation of acetophenone was discussed.展开更多
Toluene methylation with methanol on H‐ZSM‐5(Z5)zeolite for the directional transformation of toluene to xylene has been industrialized.However,great challenges remain because of the high energy barrier of methanol ...Toluene methylation with methanol on H‐ZSM‐5(Z5)zeolite for the directional transformation of toluene to xylene has been industrialized.However,great challenges remain because of the high energy barrier of methanol deprotonation to the methoxy group,the side reaction of methanol to olefins,coke formation,and the deactivation of zeolites.Herein,we report the toluene methylation coupled with CO hydrogenation to showcase an enhancement in para‐xylene(PX)selectivity by employing a bifunctional catalyst composed of ZnZrO_(x)(ZZO)and modified Z5.The results showed that a PX selectivity of up to 81.8%in xylene and xylene selectivity of 64.8%in hydrocarbons at 10.3%toluene conversion can be realized over the bifunctional catalyst on a fixed‐bed reactor.The selectivity of gaseous hydrocarbons decreased to 10.9%,and approximately half of that was observed in methanol reagent route where the PX selectivity in xylene was 38.8%.We observed that the acid strength,the quantity ratio of Brönsted and Lewis acid sites,and the pore size of zeolites were essential for the PX selectivity.The investigation of the H_(2)/D_(2) kinetic isotope effect revealed that the newborn methyl group in xylene resulted from the hydrogenation of CO rather than toluene disproportionation.Furthermore,the catalyst showed no evident deactivation within the 100 h stability test.The findings offer a promising route for the production of value‐added PX with high selectivity via toluene methylation coupled with syngas conversion.展开更多
On the basis of single factor tests, the effect of trace elements—Fe2+, Co2+ and Ni2+ ions—on biological methane production from heavy oil was investigated by the response surface method. A three-level Box-Behnken d...On the basis of single factor tests, the effect of trace elements—Fe2+, Co2+ and Ni2+ ions—on biological methane production from heavy oil was investigated by the response surface method. A three-level Box-Behnken design was employed to study the relationship between the independent variables and the dependent variable by applying initial Fe2+, Co2+ and Ni2+ concentration as the independent variables(factors) and using the methane production after 270 days of cultivation as the dependent variable(response). A prediction model of quadramatic polynomial regression equation was obtained. The results showed that the methane production could be as high as 240.69 μmol after optimization compared with 235.74 μmol obtained under un-optimized condition. Furthermore, the microbial communities before and after biodegradation were analyzed by PCR-DGGE method. The dominant bands were recovered and sequenced. Three strains were obtained; the strain T1 has 97% similarity with Bacillus thermoamylovorans, the strain H3 has 97% similarity with Bacillus thermoamylovorans and the strain H4 has 99% similarity with Bacillus vietnamensis.展开更多
Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis...Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.展开更多
Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)havin...Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.展开更多
According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo0.4Fe...According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo0.4Fe0.5Zr0.1O3-δ oxide-based membranes were systematically compared in terms of oxygen permeability and chemical stability,and their differences were elucidated by means of the theoretical calculation.For the oxygen permeability,the asymmetric membrane was greater than the symmetric membrane due to the significant decrease of bulk diffusion resistance in the thin dense layer of the asymmetric membrane.In regard to the chemical stability,the increase of oxygen partial pressure on the asymmetric membrane surface at CH4 side produced the stable time of over 1032h in partial oxidation of methane at 1123K,while the symmetric membrane was only of 528h.This study demonstrated that the asymmetric membrane was a promising geometrical configuration for the practical application.展开更多
文摘Synthesis of fourteen new complexes of meso-tetrakis（4-alkoxyphenyl） porphyrins with Co2+, Cu2+, Zn2+, Pb2+ were presented in this paper. Meso-tetrakis （4-alkoxyphenyl） porphyrins were prepared by condensation of 4-alkoxybenzaldehydes with pyrrole, then treated with corresponding metallic acetate to produce mentioned complexes, IR, UV, 1H NMR, MS and elementary analysis were explored to confirm the structures of all theses new complexes. Characteristic spectrometric data of IR, UV, 1H NMR related to these complexes have been systematically summarized. Ten of the fourteen complexes were found to exhibit liquid crystal properties.
文摘Two new ent-kauranoids, tenuifolin A (3beta,6alpha, 15beta-trihydroxy-1alpha, 7beta-diacetoxy-11beta, 16beta-epoxy-ent-kaurane) (1) and tenuifolin B (1alpha,6alpha, 11beta-trihydroxy-3beta,7beta-diacetoxy-ent-kaur-16-en-15-one) (2), together with four known compounds were isolated from the aerial parts of Isodon tenuifolia (W. W. Smith) Kudo collected from Zhongdian County, Yunnan Province, China. Their structures were determined by the spectral methods (including 2D NMR techniques).
文摘A comparative analysis of the codon usage bias was conducted in Methanosarcina mazei str. Goel and two related Euryarchaeota microorganisms （Picrophilus torridus str. DSM 9790 and Natronomonas pharaonis str. DSM 2160）. Results revealed that synonymous codon usage in Methanosarcina mazei str. Goel was less biased, which was highly correlated with the GC3S value. And the codon usage patterns were phylogenetically conserved among those Euryarchaeota microorganisms. By employing a hierarchical clustering analysis, it can be seen that it is more the species than the gene function that determines their gene codon usage pattems. Considering that those microorganisms live in different environments where the pH conditions vary quite a lot, it can be presumed that their living environments, especially the pH conditions, play an important role in determining those microorganisms＇ codon usage pattems.
文摘fragments, F- and Cl- including two isotope species 35Cl- and 37Cl-, are observed in the photoexcitations of CFC13. The ion-pair anion efficiency spectra of 35Cl- and 37Cl- are recorded in the photon energy range of 7.75-22.00 eV. The threshold of ion-pair dissociation CFCl3-CFC12＋＋Cl- is experimentally determined to be 7.944-0.04 eV. With the references of the high-resolution photoabsorption spectra reported in the literatures, we make tentative assignments of the electron valence-to-Rydberg transitions. Furthermore, the multibody ion-pair fragmentation processes to Cl- are discussed by comparison between the calculated thermochemical thresholds and the experimental efficiency spectrum.
文摘Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these data, the excess molar volume and deviations in viscosity have been calculated. The computed quantities have been fitted to the Redlich-Kister Equation to derive coefficients and estimate the standard error values. Results are discussed in terms of intermolecular interactions.
文摘Pyrolysis of polytrimethylene terephthalate(PTT) fiber has been investigated by pyrolysis gas chromatography-mass spectroscopy in the temperature range from 400℃ to 750℃ in order to observe the possible effect of the temperature on its composition of pyrolysates.At 400℃,pyrolysis of molecular chain could occur,only 13 pyrolysates could be identified.The trimethylene moieties bound to the macromolecular core by ester bonds are cleaved at around 400℃.At 550℃-750℃,pyrolysis of molecular chain could completely take place,46 pyrolysates could be found.As the temperature increases,the compositions of pyrolysate are distinctly increased.Several compounds,especially benzoic acid,monopropenyl-p-phthalate,2-propenyl benzoate,di-2-propenyl ester,1,4-benzenedicarboxylic acid,benzene,1,5-hexadiene,biphenyl and 1,3-propanediol dibenzoate could be formed.The thermal degradation mechanism,which is determined by structure and amount of the thermal decomposition products,are described.During pyrolysis of polytrimethylene terephthalate,polymeric chain scissions take place a peeling reaction as a successive removal of the dimer units from the polymeric chain.The chain scissions are followed by the elimination reaction,linkage action and secondary reactions,which bring about a variety fragment.
文摘Asymmetric hydrisilylation catalyzed by polymeric thiazolidine rhodium catalystswas conducted. Almost the same optical yields have been obtained when comb-shapedpolymeric ligands and their corresponding monomer complexed rhodium cataltystswere used to asymmetric hydrosilylation of acetophenone. Optical yield of chira 1- methylbenzyl alcohol reaches as high as 71.5%. Temperature dependence of enantio- selective hydrosilylation of acetophenone was discussed.
文摘Toluene methylation with methanol on H‐ZSM‐5(Z5)zeolite for the directional transformation of toluene to xylene has been industrialized.However,great challenges remain because of the high energy barrier of methanol deprotonation to the methoxy group,the side reaction of methanol to olefins,coke formation,and the deactivation of zeolites.Herein,we report the toluene methylation coupled with CO hydrogenation to showcase an enhancement in para‐xylene(PX)selectivity by employing a bifunctional catalyst composed of ZnZrO_(x)(ZZO)and modified Z5.The results showed that a PX selectivity of up to 81.8%in xylene and xylene selectivity of 64.8%in hydrocarbons at 10.3%toluene conversion can be realized over the bifunctional catalyst on a fixed‐bed reactor.The selectivity of gaseous hydrocarbons decreased to 10.9%,and approximately half of that was observed in methanol reagent route where the PX selectivity in xylene was 38.8%.We observed that the acid strength,the quantity ratio of Brönsted and Lewis acid sites,and the pore size of zeolites were essential for the PX selectivity.The investigation of the H_(2)/D_(2) kinetic isotope effect revealed that the newborn methyl group in xylene resulted from the hydrogenation of CO rather than toluene disproportionation.Furthermore,the catalyst showed no evident deactivation within the 100 h stability test.The findings offer a promising route for the production of value‐added PX with high selectivity via toluene methylation coupled with syngas conversion.
基金supported by the National Natural Science Foundation of China under Grant No.21307160the Natural Science Foundation of Shandong Province under Grant No.ZR2013EEQ030the Fundamental Research Funds for the Central Universities under Grant No.R1404005A
文摘On the basis of single factor tests, the effect of trace elements—Fe2+, Co2+ and Ni2+ ions—on biological methane production from heavy oil was investigated by the response surface method. A three-level Box-Behnken design was employed to study the relationship between the independent variables and the dependent variable by applying initial Fe2+, Co2+ and Ni2+ concentration as the independent variables(factors) and using the methane production after 270 days of cultivation as the dependent variable(response). A prediction model of quadramatic polynomial regression equation was obtained. The results showed that the methane production could be as high as 240.69 μmol after optimization compared with 235.74 μmol obtained under un-optimized condition. Furthermore, the microbial communities before and after biodegradation were analyzed by PCR-DGGE method. The dominant bands were recovered and sequenced. Three strains were obtained; the strain T1 has 97% similarity with Bacillus thermoamylovorans, the strain H3 has 97% similarity with Bacillus thermoamylovorans and the strain H4 has 99% similarity with Bacillus vietnamensis.
文摘Palladium‐catalyzed asymmetric allylic alkylation(AAA)of vinyl benzoxazinanones has become an important strategy for the synthesis of chiral nitrogen‐containing heterocycle compounds.However,the asymmetric synthesis of linear‐selective products has rarely been reported.The simultaneous control of regio‐,E/Z‐and enantioselectivities constitutes a major challenge and inhibits the advancement of this chemistry.Herein,we present a palladium‐catalyzed AAA of vinyl benzoxazinanones withα‐thiocyanato ketones,affording various chiral thiocyanates characterized with high linear‐,E‐and stereoselectivities.The reaction has a broad substrate scope and the chiral thiocyanates can be transformed to useful heterocycles.Experimental and computational studies suggest an inner‐sphere mechanism for AAA process,which results from the acidic and coordination effect of the nucleophilic substrates with palladium catalyst.
文摘Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.
基金Supported by the National Basic Research Program of China （2009CB623406）, the National Natural Science Foundation of China （20636020）, the National High Technology Research and Development Program of China （2006AA030204） and the Specialized Research Fund for the Doctoral Program of Higher Education of China （20060291003）.
文摘According to the configuration,mixed-conducting membranes are classified as symmetric membranes and asymmetric membranes consisting of a thin dense layer and a porous support.In this study,these two kinds of SrCo0.4Fe0.5Zr0.1O3-δ oxide-based membranes were systematically compared in terms of oxygen permeability and chemical stability,and their differences were elucidated by means of the theoretical calculation.For the oxygen permeability,the asymmetric membrane was greater than the symmetric membrane due to the significant decrease of bulk diffusion resistance in the thin dense layer of the asymmetric membrane.In regard to the chemical stability,the increase of oxygen partial pressure on the asymmetric membrane surface at CH4 side produced the stable time of over 1032h in partial oxidation of methane at 1123K,while the symmetric membrane was only of 528h.This study demonstrated that the asymmetric membrane was a promising geometrical configuration for the practical application.
