Hybrid proton conducting membranes of poly（vinyl alcohol） （PVA） and phosphomolybdic acid （PMA） were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane prop...Hybrid proton conducting membranes of poly（vinyl alcohol） （PVA） and phosphomolybdic acid （PMA） were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane properties and proton conductivity were investigated. The crosslinking reaction between the hydroxyl group of PVA and the aldehyde group of glutaraldehyde （GA） was characterized by IR spectroscopy. Proton conductivity of the membranes increases with an increase in concentration of the doped PMA and also with an increase in crosslinking density of the membranes. Proton conductivity results indicate that a significant amount of PMA was maintained in the membranes even after several hours of immersion in water. A maximum conductivity of 0.0101 S cm^-1 was obtained for the membrane with 33.3 wt% PMA and crosslinking density of 5.825 mol%. X-ray diffraction studies were carried out to investigate the influence of PMA doping and crosslinking density on the nature of the membranes. These properties make them very good candidates for polymer electrolyte membranes for direct methanol fuel cell application.展开更多
The reaction of Pr（Ⅲ） salt with 1,2,4,5-benzenetetracarboxylic acid（H4betc） and piperazine（pip） yielded a lanthanide metal-organic framework {[Pr（betc）（H2O）2]（H2pip）0.5}n（1）under hydrothermal conditions...The reaction of Pr（Ⅲ） salt with 1,2,4,5-benzenetetracarboxylic acid（H4betc） and piperazine（pip） yielded a lanthanide metal-organic framework {[Pr（betc）（H2O）2]（H2pip）0.5}n（1）under hydrothermal conditions. Compound 1 was characterized by single-crystal X-ray structural analysis, elemental analysis, IR, X-ray powder diffraction, and thermal gravimetric. Compound 1crystallizes in monoclinic, space group P21/n with a = 11.023（5）, b = 11.109（5）, c = 11.456（5） A, β = 110.065（5）°, V = 1317.7（9） A3, Mr = 471.14, Z = 4, F（000） = 920, Dc = 2.375 g/cm^3, μ（Mo Kα） = 3.761 mm-1, the final R = 0.0286 and w R = 0.0821（I 〉 2σ（I））. Compound 1 exhibits a 2D network with（4, 4） topology, and a 3D supramolecular framework formed by hydrogen-bonding interactions. The proton conductivity of compound 1 has been investigated at ~97% relative humidity and different temperature.展开更多
A proton-transfer complex of 1,2,4,5-benzenetetracarboxylic acid（H4 BTC）with 1,10-phenanthroline（phen）[（H2BTC）^2-·2（Hphen）^＋·（H4BTC）]was synthesized and characterized by IR,UV-Vis spectra and lumi...A proton-transfer complex of 1,2,4,5-benzenetetracarboxylic acid（H4 BTC）with 1,10-phenanthroline（phen）[（H2BTC）^2-·2（Hphen）^＋·（H4BTC）]was synthesized and characterized by IR,UV-Vis spectra and luminescence. The structure was determined by X-ray single crystal diffraction.It crystallizes in the triclinic system,space group P-1 with a=7.3767（15）,b=10.704（2）,c=12.890（3）A.α=102.96（3）,β105.71（3）,γ=99.68（3）°,V=926.0（3）A^3,Dc=1.558g/cm^3,Z=2,μ（Mo-Kα）=0.121mm^-1 and F（000）=448.The final R=0.0401 and wR=0.0862 for 2983 observe reflections with[1〉2σ（I）].It is composed of discrete H4 BTC molecules,H2BTC^2- ANIONS AND [Hphen]^＋ cations.The extensive hydrogen-bonding associations fonned between the H4 BTC molecules and H2BTC^2- anions result in the formation of a two-dimensional layer,to which the [Hphen]^＋ cations are attached through the hydrogen bonds formed between the carboxyl groups of H4 BTC and the NH groups of [Hphen]^＋.Under the excitation of UV light.it emits an intense blue luminescence.展开更多
The modern lifestyle caters to an increase in the incidence of peptic ulcer disease,gastroesophageal reflux disease and several other acid-related conditions of the gut. The drugs to prevent these conditions work eith...The modern lifestyle caters to an increase in the incidence of peptic ulcer disease,gastroesophageal reflux disease and several other acid-related conditions of the gut. The drugs to prevent these conditions work either through H2 receptor blockade or inhibition of the H^+, K^+ ATPase enzyme. Although proton pump inhibitors have been proven to be efficacious, they have a slow onset of action with limited resolution of symptoms in most patients. Potassium-competitive acid blockers(P-CABs) are novel drugs that bind reversibly to K^+ ions and block the H^+, K^+ ATPase enzyme, thus preventing acid production. P-CABs have a fast onset of action and have dose-dependent effects on acid production. Animal studies exist that differentiate the better results of P-CABs from proton pump inhibitors; further human trials will give a comprehensive picture of the results and will help to elucidate the therapeutic benefits of this new group of drugs.展开更多
With introduction of a diisopropyloxy phosphoryl group into the N terminal of amino acids, it was found that proton affinity (PA) of amino acid was enhanced in mass spectrometry. Density functional theory calculation...With introduction of a diisopropyloxy phosphoryl group into the N terminal of amino acids, it was found that proton affinity (PA) of amino acid was enhanced in mass spectrometry. Density functional theory calculations showed that the energy for protonation of DIPP-amino acid is lower than that of amino acid, which means PA of DIPP-AA is higher than that of corresponding amino acid. These results, coincident with our empirical results, offer a useful interpretation of experimental observations.展开更多
The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional....The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional. The complex is connected through two different types of inter-molecular hydrogen bonds. After photo-excitation, both hydrogen bonds get strengthened, which can facilitate the ESDPT reaction. The scanned potential energy curve along the proton transfer coordinate indicates that the ESDPT reaction proceeds in a stepwise pattern.展开更多
A heterometal-organic framework {[Pr2Ca（betc）2（H2O）7]·H2O}n（1） was prepared by the hydrothermal reaction of 1,2,4,5-benzenetetracarboxylic acid（H4betc） with Pr（NO3）3 and CaCO3, and further characterized...A heterometal-organic framework {[Pr2Ca（betc）2（H2O）7]·H2O}n（1） was prepared by the hydrothermal reaction of 1,2,4,5-benzenetetracarboxylic acid（H4betc） with Pr（NO3）3 and CaCO3, and further characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Complex 1 crystallizes in triclinic, space group P1 with a = 7.3668（12）, b = 10.1726（14）, c = 11.2264（15） A, a = 100.404（2）, b = 106.113（3）, g = 109.158（3）o, V = 728.48（19） A3, Mr = 966.26, Z = 1, F（000） = 470, Dc = 2.203 g/cm3, m（Mo Kα） = 3.585 mm-1, the final R = 0.0195 and w R = 0.0470（I 〉 2s（I））. Complex 1 is a 3D network with pcu topology with 1D porosity and rich hydrogen-bonding interactions. The proton conductivity of complex 1 was also studied under ~97% relative humidity and the different temperature conditions.展开更多
A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethox...A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethoxysilane（A-TES） and benzyltetrazole-modified triethoxysilane（BT-TES）.The dual-curing approach including UV-curing and thermal curing was used to obtain the crosslinked membranes.Polyethylene glycol（400） diacrylate（PEGDA） was used as an oligomer to form the polymeric matrix.The molecular structures of precursors were characterized by 1 H,13 C and 29 Si NMR spectra.The thermogravimetric analysis（TGA） results show that the membranes exhibit acceptable thermal stability for their application at above 200 oC.The differential scanning calorimeter（DSC） determination indicates that the crosslinked membranes with the mass ratios of below 1.6 of BT-TES to A-TES and the same mass of H3PO4 doped as that of A-TES possess the-T g s,and the lowest T g（-28.9 ℃） exists for the membrane with double mass of H3PO4 doped as well.The high proton conductivity in a range of 9.4―17.3 mS/cm with the corresponding water uptake of 19.1%―32.8% of the membranes was detected at 90 oC under wet conditions.Meanwhile,the proton conductivity in a dry environment for the membrane with a mass ratio of 2.4 of BT-TES to A-TES and double H3PO4 loading increases from 4.89×10-2 mS/cm at 30 ℃ to 25.7 mS/cm at 140 ℃.The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in the polymer electrolyte membrane fuel cells.展开更多
Polybenzimidazole containing ether bond（OPBI） was reinforced with silicon carbide whisker（m Si C） modified by 3-aminopropyltriethoxysilane（KH550）, and then doped with phosphoric acid（PA） to obtain OPBI/m Si C/...Polybenzimidazole containing ether bond（OPBI） was reinforced with silicon carbide whisker（m Si C） modified by 3-aminopropyltriethoxysilane（KH550）, and then doped with phosphoric acid（PA） to obtain OPBI/m Si C/PA membranes. These OPBI/m Si C/PA membranes have excellent mechanical strength and oxidative stability and can be used for high temperature proton exchange membrane（HT-PEM）. The tensile strength of OPBI/m Si C/PA membranes ranges from 27.3 to 36.8 MPa, and it increases at first and then decreases with the increase of m Si C content. The high m Si C content and PA doping level contribute to improving the proton conductivity of membranes. The proton conductivity of PBI/m Si C-10/PA membrane is 27.1 m S cm-1 at 170℃ without humidity, with an increase of 55.7% compared with that of OPBI/PA membrane. These excellent properties make OPBI/m Si C/PA membranes promising membrane materials for HT-PEM applications.展开更多
AIM:To evaluate the effect of proton pump inhibitors(PPIs) on the development of gastrointestinal tuberculosis.METHODS:All patients who were more than 20 years old and who had received a prescription for PPIs among th...AIM:To evaluate the effect of proton pump inhibitors(PPIs) on the development of gastrointestinal tuberculosis.METHODS:All patients who were more than 20 years old and who had received a prescription for PPIs among those who visited Seoul National University Hospital from January 1,2005 to December 31,2009 were identified.Due to the low sensitivity of the microbiologic test and the nonspecific pathologic findings,the diagnosis of gastrointestinal tuberculosis was confirmed through the presence of active ulcerations and the responses to anti-tuberculosis medications.The patients were divided into two groups according to treatment duration(group 1:≤ 3 mo;group 2:> 3 mo) and were followed up from the time they took the first prescription of PPIs until their last visit.Logistic regression analysis was used to calculate the relative risks(RR) and 95%CI,adjusting for covariates.RESULTS:Among the 61 834 patients exposed to PPIs(50 534 in group 1;11 300 in group 2),21 patients were diagnosed with PPI-associated gastrointestinal tuberculosis during 124 274 person-years of follow-up.Of 21 patients,the 12 who revealed only scar changes in the colonoscopy were excluded from the statistical analyses.Of those who remained,2 were excluded because they underwent gastrointestinal endoscopy within 4 wk of the first prescription for PPIs.Longer exposure to PPI was associated with a higher mean age(55.0 ± 14.5 in group 1 vs 58.2 ± 13.3 in group 2,P < 0.001) and a higher Charlson co-morbidity index(0.50 ± 0.93 in group 1 vs 0.77 ± 1.14 in group 2,P < 0.001).The true incidence of active gastrointestinal tuberculosis was 0.65 per 1000 person-years in group 1 and 0.03 per 1 000 person-years in group 2.Like the less-than-three-month PPI treatment period in group 1,the over-three-month PPI therapy period in group 2 was not associated with increased risk of acquiring gastrointestinal tuberculosis,after adjusting for age and co-morbidities,whereas the Charlson co-morbidity index was associated with increased risk of acquiring gastrointestinal tuberculosis based on the score [RR:(reference 1) in group 1 vs 1.518 in group 2;95% CI:1.040-2.216,P = 0.03].CONCLUSION:Long-term PPI therapy does not seem to be associated with increased risk of acquiring gastrointestinal tuberculosis,but a higher Charlson comorbidity index is associated with such.展开更多
文摘Hybrid proton conducting membranes of poly（vinyl alcohol） （PVA） and phosphomolybdic acid （PMA） were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane properties and proton conductivity were investigated. The crosslinking reaction between the hydroxyl group of PVA and the aldehyde group of glutaraldehyde （GA） was characterized by IR spectroscopy. Proton conductivity of the membranes increases with an increase in concentration of the doped PMA and also with an increase in crosslinking density of the membranes. Proton conductivity results indicate that a significant amount of PMA was maintained in the membranes even after several hours of immersion in water. A maximum conductivity of 0.0101 S cm^-1 was obtained for the membrane with 33.3 wt% PMA and crosslinking density of 5.825 mol%. X-ray diffraction studies were carried out to investigate the influence of PMA doping and crosslinking density on the nature of the membranes. These properties make them very good candidates for polymer electrolyte membranes for direct methanol fuel cell application.
基金supported by National Natural Science Foundation of China(21401147)Basic Research Program of Natural Science from Shaanxi Provincial Government(2015JQ2032)+2 种基金Scientific Research Program from Education Department of Shaanxi Provincial Government(2013JK0654)Opening Foundation from State Key Laboratory of Coordination Chemistry in Nanjing University(201219)the Program for Distinguished Young Scholars of Xi’an Polytechnic University(201403)
文摘The reaction of Pr（Ⅲ） salt with 1,2,4,5-benzenetetracarboxylic acid（H4betc） and piperazine（pip） yielded a lanthanide metal-organic framework {[Pr（betc）（H2O）2]（H2pip）0.5}n（1）under hydrothermal conditions. Compound 1 was characterized by single-crystal X-ray structural analysis, elemental analysis, IR, X-ray powder diffraction, and thermal gravimetric. Compound 1crystallizes in monoclinic, space group P21/n with a = 11.023（5）, b = 11.109（5）, c = 11.456（5） A, β = 110.065（5）°, V = 1317.7（9） A3, Mr = 471.14, Z = 4, F（000） = 920, Dc = 2.375 g/cm^3, μ（Mo Kα） = 3.761 mm-1, the final R = 0.0286 and w R = 0.0821（I 〉 2σ（I））. Compound 1 exhibits a 2D network with（4, 4） topology, and a 3D supramolecular framework formed by hydrogen-bonding interactions. The proton conductivity of compound 1 has been investigated at ~97% relative humidity and different temperature.
文摘A proton-transfer complex of 1,2,4,5-benzenetetracarboxylic acid（H4 BTC）with 1,10-phenanthroline（phen）[（H2BTC）^2-·2（Hphen）^＋·（H4BTC）]was synthesized and characterized by IR,UV-Vis spectra and luminescence. The structure was determined by X-ray single crystal diffraction.It crystallizes in the triclinic system,space group P-1 with a=7.3767（15）,b=10.704（2）,c=12.890（3）A.α=102.96（3）,β105.71（3）,γ=99.68（3）°,V=926.0（3）A^3,Dc=1.558g/cm^3,Z=2,μ（Mo-Kα）=0.121mm^-1 and F（000）=448.The final R=0.0401 and wR=0.0862 for 2983 observe reflections with[1〉2σ（I）].It is composed of discrete H4 BTC molecules,H2BTC^2- ANIONS AND [Hphen]^＋ cations.The extensive hydrogen-bonding associations fonned between the H4 BTC molecules and H2BTC^2- anions result in the formation of a two-dimensional layer,to which the [Hphen]^＋ cations are attached through the hydrogen bonds formed between the carboxyl groups of H4 BTC and the NH groups of [Hphen]^＋.Under the excitation of UV light.it emits an intense blue luminescence.
文摘The modern lifestyle caters to an increase in the incidence of peptic ulcer disease,gastroesophageal reflux disease and several other acid-related conditions of the gut. The drugs to prevent these conditions work either through H2 receptor blockade or inhibition of the H^+, K^+ ATPase enzyme. Although proton pump inhibitors have been proven to be efficacious, they have a slow onset of action with limited resolution of symptoms in most patients. Potassium-competitive acid blockers(P-CABs) are novel drugs that bind reversibly to K^+ ions and block the H^+, K^+ ATPase enzyme, thus preventing acid production. P-CABs have a fast onset of action and have dose-dependent effects on acid production. Animal studies exist that differentiate the better results of P-CABs from proton pump inhibitors; further human trials will give a comprehensive picture of the results and will help to elucidate the therapeutic benefits of this new group of drugs.
基金the National Natural Science Foundation of China (No. 20175026) the Ministry of Science and Technology of China the Education Ministry of China and Tsinghua University for financial support.
文摘With introduction of a diisopropyloxy phosphoryl group into the N terminal of amino acids, it was found that proton affinity (PA) of amino acid was enhanced in mass spectrometry. Density functional theory calculations showed that the energy for protonation of DIPP-amino acid is lower than that of amino acid, which means PA of DIPP-AA is higher than that of corresponding amino acid. These results, coincident with our empirical results, offer a useful interpretation of experimental observations.
文摘The excited-state double-proton transfer （ESDPT） mechanism of 2-amino-3-methoxypyridine and acetic acid com- plex is studied by the density functional theory （DFT） and time-dependent DFT with CAM-B3LYP functional. The complex is connected through two different types of inter-molecular hydrogen bonds. After photo-excitation, both hydrogen bonds get strengthened, which can facilitate the ESDPT reaction. The scanned potential energy curve along the proton transfer coordinate indicates that the ESDPT reaction proceeds in a stepwise pattern.
基金supported by the National Natural Science Foundation of China(21401147 and 21301134)Basic Research Program of Natural Science from Shaanxi Provincial Government(2015JQ2032)+2 种基金Scientific Research Program from Education Department of Shaanxi Provincial Government(2013JK0654)Opening Foundation from State Key Laboratory of Coordination Chemistry in Nanjing University(201219)the Program for Distinguished Young Scholars of Xi’an Polytechnic University(201403)
文摘A heterometal-organic framework {[Pr2Ca（betc）2（H2O）7]·H2O}n（1） was prepared by the hydrothermal reaction of 1,2,4,5-benzenetetracarboxylic acid（H4betc） with Pr（NO3）3 and CaCO3, and further characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Complex 1 crystallizes in triclinic, space group P1 with a = 7.3668（12）, b = 10.1726（14）, c = 11.2264（15） A, a = 100.404（2）, b = 106.113（3）, g = 109.158（3）o, V = 728.48（19） A3, Mr = 966.26, Z = 1, F（000） = 470, Dc = 2.203 g/cm3, m（Mo Kα） = 3.585 mm-1, the final R = 0.0195 and w R = 0.0470（I 〉 2s（I））. Complex 1 is a 3D network with pcu topology with 1D porosity and rich hydrogen-bonding interactions. The proton conductivity of complex 1 was also studied under ~97% relative humidity and the different temperature conditions.
基金Supported by the National Natural Science Foundation of China(No.50973100)
文摘A series of novel amphibious organic/inorganic hybrid proton exchange membranes with H3PO4 doped which could be used under both wet and dry conditions was prepared through a sol-gel process based on acrylated triethoxysilane（A-TES） and benzyltetrazole-modified triethoxysilane（BT-TES）.The dual-curing approach including UV-curing and thermal curing was used to obtain the crosslinked membranes.Polyethylene glycol（400） diacrylate（PEGDA） was used as an oligomer to form the polymeric matrix.The molecular structures of precursors were characterized by 1 H,13 C and 29 Si NMR spectra.The thermogravimetric analysis（TGA） results show that the membranes exhibit acceptable thermal stability for their application at above 200 oC.The differential scanning calorimeter（DSC） determination indicates that the crosslinked membranes with the mass ratios of below 1.6 of BT-TES to A-TES and the same mass of H3PO4 doped as that of A-TES possess the-T g s,and the lowest T g（-28.9 ℃） exists for the membrane with double mass of H3PO4 doped as well.The high proton conductivity in a range of 9.4―17.3 mS/cm with the corresponding water uptake of 19.1%―32.8% of the membranes was detected at 90 oC under wet conditions.Meanwhile,the proton conductivity in a dry environment for the membrane with a mass ratio of 2.4 of BT-TES to A-TES and double H3PO4 loading increases from 4.89×10-2 mS/cm at 30 ℃ to 25.7 mS/cm at 140 ℃.The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in the polymer electrolyte membrane fuel cells.
基金financially sponsored by the Kunlun Scholar Award Program of Qinghai Provincethe Fundamental Research Funds for the Central Universities (WD1315012)
文摘Polybenzimidazole containing ether bond（OPBI） was reinforced with silicon carbide whisker（m Si C） modified by 3-aminopropyltriethoxysilane（KH550）, and then doped with phosphoric acid（PA） to obtain OPBI/m Si C/PA membranes. These OPBI/m Si C/PA membranes have excellent mechanical strength and oxidative stability and can be used for high temperature proton exchange membrane（HT-PEM）. The tensile strength of OPBI/m Si C/PA membranes ranges from 27.3 to 36.8 MPa, and it increases at first and then decreases with the increase of m Si C content. The high m Si C content and PA doping level contribute to improving the proton conductivity of membranes. The proton conductivity of PBI/m Si C-10/PA membrane is 27.1 m S cm-1 at 170℃ without humidity, with an increase of 55.7% compared with that of OPBI/PA membrane. These excellent properties make OPBI/m Si C/PA membranes promising membrane materials for HT-PEM applications.
基金Supported by Basic Science Research Program through a National Research Foundation of Korea Grant Funded by the Ministry of Education,Science,and Technology,No. 2011-0018257Systems Biomedical Informatics National Core Research Center
文摘AIM:To evaluate the effect of proton pump inhibitors(PPIs) on the development of gastrointestinal tuberculosis.METHODS:All patients who were more than 20 years old and who had received a prescription for PPIs among those who visited Seoul National University Hospital from January 1,2005 to December 31,2009 were identified.Due to the low sensitivity of the microbiologic test and the nonspecific pathologic findings,the diagnosis of gastrointestinal tuberculosis was confirmed through the presence of active ulcerations and the responses to anti-tuberculosis medications.The patients were divided into two groups according to treatment duration(group 1:≤ 3 mo;group 2:> 3 mo) and were followed up from the time they took the first prescription of PPIs until their last visit.Logistic regression analysis was used to calculate the relative risks(RR) and 95%CI,adjusting for covariates.RESULTS:Among the 61 834 patients exposed to PPIs(50 534 in group 1;11 300 in group 2),21 patients were diagnosed with PPI-associated gastrointestinal tuberculosis during 124 274 person-years of follow-up.Of 21 patients,the 12 who revealed only scar changes in the colonoscopy were excluded from the statistical analyses.Of those who remained,2 were excluded because they underwent gastrointestinal endoscopy within 4 wk of the first prescription for PPIs.Longer exposure to PPI was associated with a higher mean age(55.0 ± 14.5 in group 1 vs 58.2 ± 13.3 in group 2,P < 0.001) and a higher Charlson co-morbidity index(0.50 ± 0.93 in group 1 vs 0.77 ± 1.14 in group 2,P < 0.001).The true incidence of active gastrointestinal tuberculosis was 0.65 per 1000 person-years in group 1 and 0.03 per 1 000 person-years in group 2.Like the less-than-three-month PPI treatment period in group 1,the over-three-month PPI therapy period in group 2 was not associated with increased risk of acquiring gastrointestinal tuberculosis,after adjusting for age and co-morbidities,whereas the Charlson co-morbidity index was associated with increased risk of acquiring gastrointestinal tuberculosis based on the score [RR:(reference 1) in group 1 vs 1.518 in group 2;95% CI:1.040-2.216,P = 0.03].CONCLUSION:Long-term PPI therapy does not seem to be associated with increased risk of acquiring gastrointestinal tuberculosis,but a higher Charlson comorbidity index is associated with such.
