Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothe...Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothermal reaction using commercially available Then single phase Gd2O2SO4：Pr powder was obtained by calcining the precursor at 750℃ for 2 h. The Gd2O2SO4：Pr powder compacts can be sintered to single phase Gd2O2S：Pr ceramics with a relative density of 99% and mean grain size of 30um at 1750℃ for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd2O2S：Pr ceramics were examined. Luminescence spectra of the Gd2O2S：Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the ^3p0-3H4 transition of Pr^3＋ ions.展开更多
Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves...Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S :0.06Ti (0≤x≤0. 10) phosphors decrease gradually with increasing Mg2+ ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S: Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photolumi-nescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2+ ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-x Mgx O2S : 0.06Ti phosphor.展开更多
A practical and scalable synthesis route of acetylphenylboronic acids is described. Bromoacetophenones(compounds 3a, 3b) were ketalized with ethylene glycol and triethyl orthoformate to give bromo ketals(compounds 4a_...A practical and scalable synthesis route of acetylphenylboronic acids is described. Bromoacetophenones(compounds 3a, 3b) were ketalized with ethylene glycol and triethyl orthoformate to give bromo ketals(compounds 4a_4c) in 60_80% yields. Compounds 4a_4b were treated with a Grignard reagent and then exchanged with borate to give p- and m-acetylphenyl boronic acids(compounds 5a and 5b) in 80% and 56% yields, respectively. The o-form(compound 5c) was obtained in 61% yield via the BuLi method.展开更多
Plasma iron is normally bound to the iron transport protein transferrin, but there are some iron ions not associated with transferrin. The latter ions are generally termed as non-transferrin-bound iron (NTBI) or labil...Plasma iron is normally bound to the iron transport protein transferrin, but there are some iron ions not associated with transferrin. The latter ions are generally termed as non-transferrin-bound iron (NTBI) or labile plasma iron. The NTBI has been thought to play an important role in iron-induced cell damage with resultant peroxidation of cell membrane lipids and other biomolecules, and such oxidative damage is implicated as an important contributor in the pathogenesis of cancer, cardiovascular disease, aging and other degenerative disorders, but little is understood about the chemical composition of NTBI and the origin of toxicity due to NTBI. In this review, we demonstrated the several chemical models for NTBI, and elucidated the chemical mechanism of iron toxicity due to NTBI in human body on the basis of my concept on the mechanism of oxygen activation in biological oxygenases. This has lead to the conclusion that 1) NTBI are divided into two groups, water-in-soluble and water-soluble ones, 2) some of the water-soluble NTBI react with oxygen or hydrogen peroxide, changing these molecules to those exhibiting the reactivity similar to singlet oxygen (1△g), and this is the main reason for NTBI to induce the oxidative stress, and 3) the responsibility of hydroxyl radical or free singlet oxygen is negligible as a “reactive oxygen species” in the human body. Based on the discussions described in this article we have proposed a new technique to prevent the oxidative damage due to NTBI. In order to achieve the purpose, we have synthesized the new superpolyphenols which contain more than 100 molecules of catechol derivative in one polymeric compound;these are sometimes water-insoluble, and in another cases, water-soluble. We have observed that some of these compounds can eliminate NTBI effectively from the plasma, and also some of these derivatives can remove hydrogen peroxide from the solution. Thus, we can hope that our new super-polyphenols should depress greatly the oxidative stress due to NTBI, which may be consistent with the facts that the Japanese tea catechins which contain polyphenols exhibit high preventing effects against lifestyle-related diseases, and that some polyphenols have been known to protect the pathogenesis of Alzheimer’s disease. We also discussed the antioxidative function by zinc(II) ion, which depresses the oxidative damage by NTBI by promoting the formation of iron deposition.展开更多
Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of amo...Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of among molecules of the same compound It provides a new and convenient method to synthesize perhaloal-kanes Apparently,it pertains to an amomc mechanism,i e.the reaction is initiated by halophilic attack on C-X bonds by the base,and an intermediate carbanion is formed.Distributions of the products depend on the equilibria involving all carbanion intermediates and perhaloalkane product molecules.展开更多
The Zn(O,S)thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se_(2)(CIGS)thin-film solar cell due to its advantages of optical responses in the short-wavelength region ...The Zn(O,S)thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se_(2)(CIGS)thin-film solar cell due to its advantages of optical responses in the short-wavelength region and adjustable bandgap.In this paper,the thin-film growth mechanism and process optimization of Zn(O,S)films fabricated using the chemical bath deposition method are sys-tematically investigated.The thickness and quality of Zn(O,S)films were found to be strongly affected by the concentration variation of the precursor chemicals.It was also revealed that different surface morphologies of Zn(O,S)films would appear if the reaction time were changed and,subsequently,the optimum reaction time was defined.The film-growth curve suggested that the growth rate varied linearly with the deposition temperature and some defects appeared when the temperature was too high.In addition,to further improve the film quality,an effective post-treatment approach was proposed and the experimental results showed that the microstructure of the Zn(O,S)thin film was improved by an ammonia etching process followed by an annealing process.For com-parison purposes,both Zn(O,S)-based and CdS-based devices were fabricated and characterized.The device with a Zn(O,S)-CIGS solar cell after post-treatment showed near conversion efficiency comparable to that of the device with the CdS-CIGS cell.展开更多
基金supported by the National Natural Sci-ence Foundation of China (Grant. No. 50672014)the National Science Fund for Distinguished Young Scholars,China (Grant No. 50425413)
文摘Fabrication of Gd2O2S：Pr scintillation ceramics by 2Gd2O3.（Gd,Pr）2（SO4）3.mH2O precursor was made Gd2O3, Pr6O11 and H2SO4 as the starting materials pressureless reaction sintering was investigated. The by hydrothermal reaction using commercially available Then single phase Gd2O2SO4：Pr powder was obtained by calcining the precursor at 750℃ for 2 h. The Gd2O2SO4：Pr powder compacts can be sintered to single phase Gd2O2S：Pr ceramics with a relative density of 99% and mean grain size of 30um at 1750℃ for 2 h in flowing hydrogen atmosphere. Densification and microstructural development of the Gd2O2S：Pr ceramics were examined. Luminescence spectra of the Gd2O2S：Pr ceramic under 309 nm UV excitation and X-ray excitation show a green emission at 511 nm as the most prominent peak, which corresponds to the ^3p0-3H4 transition of Pr^3＋ ions.
基金Project supported by SRF for ROCS, SEM (2003-14), and Science and Technology Department of Zhejiang Province (2005C31019)
文摘Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S :0.06Ti (0≤x≤0. 10) phosphors decrease gradually with increasing Mg2+ ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S: Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photolumi-nescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2+ ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-x Mgx O2S : 0.06Ti phosphor.
基金the National Nature Science Foundation of China(No.30 17110)
文摘A practical and scalable synthesis route of acetylphenylboronic acids is described. Bromoacetophenones(compounds 3a, 3b) were ketalized with ethylene glycol and triethyl orthoformate to give bromo ketals(compounds 4a_4c) in 60_80% yields. Compounds 4a_4b were treated with a Grignard reagent and then exchanged with borate to give p- and m-acetylphenyl boronic acids(compounds 5a and 5b) in 80% and 56% yields, respectively. The o-form(compound 5c) was obtained in 61% yield via the BuLi method.
文摘Plasma iron is normally bound to the iron transport protein transferrin, but there are some iron ions not associated with transferrin. The latter ions are generally termed as non-transferrin-bound iron (NTBI) or labile plasma iron. The NTBI has been thought to play an important role in iron-induced cell damage with resultant peroxidation of cell membrane lipids and other biomolecules, and such oxidative damage is implicated as an important contributor in the pathogenesis of cancer, cardiovascular disease, aging and other degenerative disorders, but little is understood about the chemical composition of NTBI and the origin of toxicity due to NTBI. In this review, we demonstrated the several chemical models for NTBI, and elucidated the chemical mechanism of iron toxicity due to NTBI in human body on the basis of my concept on the mechanism of oxygen activation in biological oxygenases. This has lead to the conclusion that 1) NTBI are divided into two groups, water-in-soluble and water-soluble ones, 2) some of the water-soluble NTBI react with oxygen or hydrogen peroxide, changing these molecules to those exhibiting the reactivity similar to singlet oxygen (1△g), and this is the main reason for NTBI to induce the oxidative stress, and 3) the responsibility of hydroxyl radical or free singlet oxygen is negligible as a “reactive oxygen species” in the human body. Based on the discussions described in this article we have proposed a new technique to prevent the oxidative damage due to NTBI. In order to achieve the purpose, we have synthesized the new superpolyphenols which contain more than 100 molecules of catechol derivative in one polymeric compound;these are sometimes water-insoluble, and in another cases, water-soluble. We have observed that some of these compounds can eliminate NTBI effectively from the plasma, and also some of these derivatives can remove hydrogen peroxide from the solution. Thus, we can hope that our new super-polyphenols should depress greatly the oxidative stress due to NTBI, which may be consistent with the facts that the Japanese tea catechins which contain polyphenols exhibit high preventing effects against lifestyle-related diseases, and that some polyphenols have been known to protect the pathogenesis of Alzheimer’s disease. We also discussed the antioxidative function by zinc(II) ion, which depresses the oxidative damage by NTBI by promoting the formation of iron deposition.
基金Project supported by the National Natural Science Foundation of China
文摘Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of among molecules of the same compound It provides a new and convenient method to synthesize perhaloal-kanes Apparently,it pertains to an amomc mechanism,i e.the reaction is initiated by halophilic attack on C-X bonds by the base,and an intermediate carbanion is formed.Distributions of the products depend on the equilibria involving all carbanion intermediates and perhaloalkane product molecules.
基金financially supported by National Key R&D Program of China(grant no.2018YFB1500200).
文摘The Zn(O,S)thin film is considered a most promising candidate for a cadmium-free buffer layer of the Cu(In,Ga)Se_(2)(CIGS)thin-film solar cell due to its advantages of optical responses in the short-wavelength region and adjustable bandgap.In this paper,the thin-film growth mechanism and process optimization of Zn(O,S)films fabricated using the chemical bath deposition method are sys-tematically investigated.The thickness and quality of Zn(O,S)films were found to be strongly affected by the concentration variation of the precursor chemicals.It was also revealed that different surface morphologies of Zn(O,S)films would appear if the reaction time were changed and,subsequently,the optimum reaction time was defined.The film-growth curve suggested that the growth rate varied linearly with the deposition temperature and some defects appeared when the temperature was too high.In addition,to further improve the film quality,an effective post-treatment approach was proposed and the experimental results showed that the microstructure of the Zn(O,S)thin film was improved by an ammonia etching process followed by an annealing process.For com-parison purposes,both Zn(O,S)-based and CdS-based devices were fabricated and characterized.The device with a Zn(O,S)-CIGS solar cell after post-treatment showed near conversion efficiency comparable to that of the device with the CdS-CIGS cell.
