By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping （0.00 ≤ x ≤0.30） on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been...By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping （0.00 ≤ x ≤0.30） on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.展开更多
Although ferroelectrics have potential applications in photocatalysis due to their highly efficient charge separation, their mechanism of charge separation is still unknown. A ferroelectric Sr0.7Ba0.3Nb2O6 （SBN‐70）...Although ferroelectrics have potential applications in photocatalysis due to their highly efficient charge separation, their mechanism of charge separation is still unknown. A ferroelectric Sr0.7Ba0.3Nb2O6 （SBN‐70） semiconductor with a low ferro‐paraelectric phase transition （65℃） was studied. The photocatalytic activity for H2 production by ferroelectric and paraelectric SBN‐70 was examined. The spontaneous polarization in the ferroelectric phase strongly affected the photocata‐lytic performance and parallel ferroelectric domains significantly promoted photogenerated charge separation to result in better photocatalytic H2 production. This knowledge provides an important basis for the fabrication of ferroelectric photocatalysts with improved charge separation ability.展开更多
AIM: To examine the relationships between γ -glutamyltransferase (GGT), alanine-aminotransferase (ALT),aspartate-aminotransferase (AST) and various metabolic parameters, C-reactive protein (CRP) and an oxidative stre...AIM: To examine the relationships between γ -glutamyltransferase (GGT), alanine-aminotransferase (ALT),aspartate-aminotransferase (AST) and various metabolic parameters, C-reactive protein (CRP) and an oxidative stress marker (nitrotyrosine, NT) in subjects without any metabolic abnormalities from a population-based sample.METHODS: Two hundred and five subjects with normal body mass index (BMI), glucose tolerance, and without any metabolic abnormality were studied out of 1339subjects, without known liver diseases, alcohol abuse or use of hepatotoxic drugs, who are representative of the 45-64 aged population of Asti (north-western Italy).RESULTS: In all patients metabolic parameters and hs-CRP levels linearly increase from the lowest to the highest ALT and GGT tertiles, while in subjects without metabolic abnormalities, there is a significant association between fasting glucose, uric acid, waist circumference,hs-CRP, triglyceride values, and GGT levels. In these subjects, male sex, higher hs-CRP and glucose levels are associated with GGT levels in a multiple regression model, after adjustments for multiple confounders.In the same model, median NT levels are significantly associated with the increasing GGT tertile (β = 1.06;95%CI 0.67-1.45), but not with the AST and ALT tertiles.In a multiple regression model, after adjusting for age,sex, BMI, waist, smoking, and alcohol consumption, both NT (β = 0.05; 95%CI 0.02-0.08) and hs-CRP levels (β =0.09; 95%CI 0.03-0.15) are significantly associated with fasting glycemia.CONCLUSION: GGT, an easy, universally standardized and available measurement, could represent an early marker of sub-clinical inflammation and oxidative stress in otherwise healthy individuals. Prospective studies are needed to establish if GGT could predict future diabetes in these subjects.展开更多
The volatilization of stibnite(Sb2S3) in nitrogen from 700 to 1000 °C was investigated by using thermogravimetric analysis. The results indicate that in inert atmosphere, stibnite can be volatilized most efficien...The volatilization of stibnite(Sb2S3) in nitrogen from 700 to 1000 °C was investigated by using thermogravimetric analysis. The results indicate that in inert atmosphere, stibnite can be volatilized most efficiently as Sb2S3(g) at a linear rate below850 °C, with activation energy of 137.18 k J/mol, and the reaction rate constant can be expressed as k=206901exp(-16.5/T). Stibnite can be decomposed into Sb and sulfur at temperature above 850 °C in a nitrogen atmosphere. However, in the presence of oxygen,stibnite is oxidized into Sb and SO2 gas at high temperature. Otherwise, Sb is oxidized quickly into antimony oxides such as Sb2O3 and Sb O2, while Sb2O3 can be volatilized efficiently at high temperature.展开更多
Artemisinin is an excellent antimalarial drug widely used in clinical medicine.However,due to the limitation of natural source of artemisinin,the chemical synthesis of artemisinin has achieved substantial attention.Di...Artemisinin is an excellent antimalarial drug widely used in clinical medicine.However,due to the limitation of natural source of artemisinin,the chemical synthesis of artemisinin has achieved substantial attention.Dihydroartemisinic acid is a key precursor for the synthesis of artemisinin.The reaction of dihydroartemisinic acid with singlet oxygen to form peroxide is a pivotal step in the photochemical preparation of artemisinin.Nevertheless,the reaction kinetics of dihydroartemisinic acid with singlet oxygen has not been investigated previously.Herein,we report the rate constants of the reaction between dihydroartemisinic acid and singlet oxygen.By directly detecting the luminescence decay kinetics of singlet oxygen at 1270 nm at room temperature,the reaction rate constants of singlet oxygen and dihydroartemisinic acid in different solvents are obtained to be 1.81×10^5(mol/L)^-1·s^-1 in CCl4,5.69×10^5(mol/L)^-1·s^-1 in CH3CN,and 3.27×10^6(mol/L)^-1·s^-1 in DMSO,respec-tively.It is found that the reaction rate constants of dihydroartemisinic acid with singlet oxygen increase as polarity of the solvent increases among the three solvents.These results provide fundamental knowledge to optimize experiment conditions of photochemical synthesis of artemisinin for improving the yields of artemisinin.展开更多
The apparent 1^st order rate constant of photodegradation of formaldehyde by carbon containing TiO2 nanoparticles has been investigated by numerical integration of mass transfer equation with measured degradation degr...The apparent 1^st order rate constant of photodegradation of formaldehyde by carbon containing TiO2 nanoparticles has been investigated by numerical integration of mass transfer equation with measured degradation degree using a tubular photoreactor. The carbon containing TiO2 nanoparticles are synthesized by the oxidation of TiCl4 in propane/air flame CVD process with futile fraction up to 0.3 and carbon mass fractions up to 0.22, respectively. Thin TiO2 film is coated on the wall of the tubular reactor by sedimentation method. Effects of rutile mass fraction and carbon content have been examined on the apparent 1 ^st order rate constant and results show that, at 570ppm of formaldehyde loaded air stream, 80% relative humidity and about 100nm thin TiOa film, the 1^st order rate constant increases with increasing rutile mass fraction up to 0.3, occurs a maximum at the carbon content of about 5% by weight and is about 2.5 times of that at carbon content about zero or above 10%.展开更多
The reaction of HO2NO2 （peroxynitric acid, PNA） with OH was studied by the hybrid density functional B3LYP and CBS-QB3 methods. Based on the calculated potential energy surface, five reaction channels, H20＋NO2＋O2,...The reaction of HO2NO2 （peroxynitric acid, PNA） with OH was studied by the hybrid density functional B3LYP and CBS-QB3 methods. Based on the calculated potential energy surface, five reaction channels, H20＋NO2＋O2, HOOH＋NO3, NO2＋HO3H, HO2＋HONO2 and HO2＋HOONO, were examined in detail. The major reaction channel is PNA＋OH→M1→TS1→H2O＋NO2＋O2. Taking a pre-equilibrium approximation and using the CBS-QB3 energies, the theoretical rate constant of this channel was calculated as 1.13×10-12 cm^3/（molecule s） at 300 K, in agreement with the experimental result. Comparison between reactions of HOONO2＋OH and HONO2＋OH was carried out. For HOR＋OH reactions, the total rate constants increase from R=NO2 to R=ONO2, which is consistent with experimental measurements.展开更多
基金This work was supported by the National Nature Science Foundation of China （No. 19934003） the State Key Project of Fundamental Research of China （No.001CB610604） the Item of Nature Science Research of Anhui （No. 2001kj244）.
文摘By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping （0.00 ≤ x ≤0.30） on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.
基金supported by the National Natural Science Foundation of China (211373213,21373212)~~
文摘Although ferroelectrics have potential applications in photocatalysis due to their highly efficient charge separation, their mechanism of charge separation is still unknown. A ferroelectric Sr0.7Ba0.3Nb2O6 （SBN‐70） semiconductor with a low ferro‐paraelectric phase transition （65℃） was studied. The photocatalytic activity for H2 production by ferroelectric and paraelectric SBN‐70 was examined. The spontaneous polarization in the ferroelectric phase strongly affected the photocata‐lytic performance and parallel ferroelectric domains significantly promoted photogenerated charge separation to result in better photocatalytic H2 production. This knowledge provides an important basis for the fabrication of ferroelectric photocatalysts with improved charge separation ability.
基金Supported by a grant: "Progetto di Ricerca Sanitaria Finalizzata,Regione Piemonte, 2003"
文摘AIM: To examine the relationships between γ -glutamyltransferase (GGT), alanine-aminotransferase (ALT),aspartate-aminotransferase (AST) and various metabolic parameters, C-reactive protein (CRP) and an oxidative stress marker (nitrotyrosine, NT) in subjects without any metabolic abnormalities from a population-based sample.METHODS: Two hundred and five subjects with normal body mass index (BMI), glucose tolerance, and without any metabolic abnormality were studied out of 1339subjects, without known liver diseases, alcohol abuse or use of hepatotoxic drugs, who are representative of the 45-64 aged population of Asti (north-western Italy).RESULTS: In all patients metabolic parameters and hs-CRP levels linearly increase from the lowest to the highest ALT and GGT tertiles, while in subjects without metabolic abnormalities, there is a significant association between fasting glucose, uric acid, waist circumference,hs-CRP, triglyceride values, and GGT levels. In these subjects, male sex, higher hs-CRP and glucose levels are associated with GGT levels in a multiple regression model, after adjustments for multiple confounders.In the same model, median NT levels are significantly associated with the increasing GGT tertile (β = 1.06;95%CI 0.67-1.45), but not with the AST and ALT tertiles.In a multiple regression model, after adjusting for age,sex, BMI, waist, smoking, and alcohol consumption, both NT (β = 0.05; 95%CI 0.02-0.08) and hs-CRP levels (β =0.09; 95%CI 0.03-0.15) are significantly associated with fasting glycemia.CONCLUSION: GGT, an easy, universally standardized and available measurement, could represent an early marker of sub-clinical inflammation and oxidative stress in otherwise healthy individuals. Prospective studies are needed to establish if GGT could predict future diabetes in these subjects.
基金Project(51204210) supported by the National Natural Science Foundation of ChinaProject(2011AA061001) supported by the National High Technology Research and Development Program of ChinaProject(2012BAC12B04) supported by the National Science&Technology Pillar Program during Twelfth Five-Year Plan of China
文摘The volatilization of stibnite(Sb2S3) in nitrogen from 700 to 1000 °C was investigated by using thermogravimetric analysis. The results indicate that in inert atmosphere, stibnite can be volatilized most efficiently as Sb2S3(g) at a linear rate below850 °C, with activation energy of 137.18 k J/mol, and the reaction rate constant can be expressed as k=206901exp(-16.5/T). Stibnite can be decomposed into Sb and sulfur at temperature above 850 °C in a nitrogen atmosphere. However, in the presence of oxygen,stibnite is oxidized into Sb and SO2 gas at high temperature. Otherwise, Sb is oxidized quickly into antimony oxides such as Sb2O3 and Sb O2, while Sb2O3 can be volatilized efficiently at high temperature.
基金supported by the National Natural Science Foundation of China (No.21773013,No.21933005and No.21425313).
文摘Artemisinin is an excellent antimalarial drug widely used in clinical medicine.However,due to the limitation of natural source of artemisinin,the chemical synthesis of artemisinin has achieved substantial attention.Dihydroartemisinic acid is a key precursor for the synthesis of artemisinin.The reaction of dihydroartemisinic acid with singlet oxygen to form peroxide is a pivotal step in the photochemical preparation of artemisinin.Nevertheless,the reaction kinetics of dihydroartemisinic acid with singlet oxygen has not been investigated previously.Herein,we report the rate constants of the reaction between dihydroartemisinic acid and singlet oxygen.By directly detecting the luminescence decay kinetics of singlet oxygen at 1270 nm at room temperature,the reaction rate constants of singlet oxygen and dihydroartemisinic acid in different solvents are obtained to be 1.81×10^5(mol/L)^-1·s^-1 in CCl4,5.69×10^5(mol/L)^-1·s^-1 in CH3CN,and 3.27×10^6(mol/L)^-1·s^-1 in DMSO,respec-tively.It is found that the reaction rate constants of dihydroartemisinic acid with singlet oxygen increase as polarity of the solvent increases among the three solvents.These results provide fundamental knowledge to optimize experiment conditions of photochemical synthesis of artemisinin for improving the yields of artemisinin.
文摘The apparent 1^st order rate constant of photodegradation of formaldehyde by carbon containing TiO2 nanoparticles has been investigated by numerical integration of mass transfer equation with measured degradation degree using a tubular photoreactor. The carbon containing TiO2 nanoparticles are synthesized by the oxidation of TiCl4 in propane/air flame CVD process with futile fraction up to 0.3 and carbon mass fractions up to 0.22, respectively. Thin TiO2 film is coated on the wall of the tubular reactor by sedimentation method. Effects of rutile mass fraction and carbon content have been examined on the apparent 1 ^st order rate constant and results show that, at 570ppm of formaldehyde loaded air stream, 80% relative humidity and about 100nm thin TiOa film, the 1^st order rate constant increases with increasing rutile mass fraction up to 0.3, occurs a maximum at the carbon content of about 5% by weight and is about 2.5 times of that at carbon content about zero or above 10%.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.20473078）.
文摘The reaction of HO2NO2 （peroxynitric acid, PNA） with OH was studied by the hybrid density functional B3LYP and CBS-QB3 methods. Based on the calculated potential energy surface, five reaction channels, H20＋NO2＋O2, HOOH＋NO3, NO2＋HO3H, HO2＋HONO2 and HO2＋HOONO, were examined in detail. The major reaction channel is PNA＋OH→M1→TS1→H2O＋NO2＋O2. Taking a pre-equilibrium approximation and using the CBS-QB3 energies, the theoretical rate constant of this channel was calculated as 1.13×10-12 cm^3/（molecule s） at 300 K, in agreement with the experimental result. Comparison between reactions of HOONO2＋OH and HONO2＋OH was carried out. For HOR＋OH reactions, the total rate constants increase from R=NO2 to R=ONO2, which is consistent with experimental measurements.
