Portulaca oleracea L. is distributed widely in China and some othercountries, which is included in the pharmacopoeias of China. In tradition, it is used in thetreatment of atheroma, and also used as antifungal and ant...Portulaca oleracea L. is distributed widely in China and some othercountries, which is included in the pharmacopoeias of China. In tradition, it is used in thetreatment of atheroma, and also used as antifungal and antiviral agents now. It also decreases bloodsugar, enhances immunity and adjusts blood lipids. The anticancer and antifungal effects ofPortulaca oleracea L. were reported in several patents. But no active component has been found. Inthis study, the chemical compositions from Portulaca oleracea L. were investigated to provideevidence for the activity of Portulaca oleracea L. .展开更多
We investigated the effects of different barium compounds on the thaumasite form of sulphate attack（TSA）resistance of cement-based materials when they were used as admixtures in mortars.Moreover,we analyzed the inhi...We investigated the effects of different barium compounds on the thaumasite form of sulphate attack（TSA）resistance of cement-based materials when they were used as admixtures in mortars.Moreover,we analyzed the inhibition mechanisms within different types of barium salts,namely BaCO_3 and Ba（OH）_2,on the thaumasite formation.The controlcement mortar and mortars with barium salts to cement and limestone weight ratios of 0.5%,1.0%,and 1.5% were immersed in 5%（by weight）MgSO_4 solution at 5 ℃ to mimic TSA.Appearance,mass,and compressive strength of the mortar samples were monitored and measured to assess the generaldegradation extent of these samples.The products of sulphate attack were further analyzed by XRD,FTIR,and SEM,respectively.Experimentalresults show that different degradation extent is evident in allmortars cured in MgSO_4 solution.However,barium salts can greatly inhibit such degradation.Barium in hydroxide form has better effectiveness in protection against TSA than carbonate form,which may be due to their solubility difference in alkaline cement pore solution,and the presence of these barium compounds can reduce the degree of TSA by comparison with the almost completely decomposed controlsamples.展开更多
The isoplethic vapor-liquid equilibria(VLE)for N,N -dimethylformamide +2-propanol+1-propanol and their binary constituent mixtures were measured by using an inclined ebulliometer with a pump-like stirrer. The comparis...The isoplethic vapor-liquid equilibria(VLE)for N,N -dimethylformamide +2-propanol+1-propanol and their binary constituent mixtures were measured by using an inclined ebulliometer with a pump-like stirrer. The comparison between the experimental results and literature for binary systems was given. The ternary VLE were predicted by using modified UNIQUAC model with temperature-dependence binary parameters.展开更多
The isomerization of CH3S（OH）CH2 to CH3S（O）CH3 in the absence and presence of water has been investigated at the G3XMP2//B3LYP/6-311 ＋ G（2df, p） level. The naked isomerization, the reaction without water, gives...The isomerization of CH3S（OH）CH2 to CH3S（O）CH3 in the absence and presence of water has been investigated at the G3XMP2//B3LYP/6-311 ＋ G（2df, p） level. The naked isomerization, the reaction without water, gives the high barrier height （21.56 kcal.mol^-1）. Three models are constructed to describe the water influence on the isomerization, that is, water molecules are the catalyst and the microsolvation, and water molecules act as the catalyst and microsolvation simultaneously. Our results show that the isomerization barrier heights of CH3S（OH）CH2 to CH3S（O）CH3 are reduced by 12.32, 11.04, and 7.80 kcal.mol^-1, respectively, when one, two, and three water molecules are performed as catalyst, in contrast to the naked isomerization. Moreover, the rate constants of the isomerization are calculated using the transition state theory with the Wigner tunneling correction over the temperature range of 240-425 K. We find that the rate constant of a single water molecule as the catalyst is 1.58 times larger than the naked isomerization at 325 K, whereas it is slower by 6 orders of magnitude when water molecule serves as the microsolvation at 325 K, compared to naked reaction. So the water-catalyzed isomerization of CH3S（OH）CH2 to CH3S（O）CH3 is predicted to be the key role in lowering the activation energy. The isomerization involving water molecules acting as mierosolvation is unfavorable under atmospheric conditions.展开更多
Doping of foreign atoms and construction of unique structures are considered as effective approaches to design high-activity and strongdurability electrocatalysts.Herein,we report Fe-doped nickel hydroxide carbonate h...Doping of foreign atoms and construction of unique structures are considered as effective approaches to design high-activity and strongdurability electrocatalysts.Herein,we report Fe-doped nickel hydroxide carbonate hierarchical microtubes with Ag nanoparticles(denoted Ag/NiFeHC HMTs)through hydrolysis precipitation process.Experimental tests and density functional theory calculations reveal that Fe doping can tune the electron configuration to enhance the conductivity,markedly improve the electrochemical surface area to expose more active sites,and act as reactive centers to lower the free energy of the rate determination step.In addition,the unique hierarchical structure can also offer active sites and excellent cycling stability.Benefitting from these advantages,the as-obtained Ag/NiFeHC HMTs show excellent oxygen evolution reaction activity,with an overpotential of 208 mV at 10 mA cm^(−2)in 1.0M KOH.Also,it could achieve long-term stability at a current density of 20 mA cm^(−2)for 24 h.展开更多
文摘Portulaca oleracea L. is distributed widely in China and some othercountries, which is included in the pharmacopoeias of China. In tradition, it is used in thetreatment of atheroma, and also used as antifungal and antiviral agents now. It also decreases bloodsugar, enhances immunity and adjusts blood lipids. The anticancer and antifungal effects ofPortulaca oleracea L. were reported in several patents. But no active component has been found. Inthis study, the chemical compositions from Portulaca oleracea L. were investigated to provideevidence for the activity of Portulaca oleracea L. .
基金Funded by the National Natural Science Foundation of China(No.51372076)the Project of Science&Technology Department of Hubei Province(No.2014BCB027)
文摘We investigated the effects of different barium compounds on the thaumasite form of sulphate attack（TSA）resistance of cement-based materials when they were used as admixtures in mortars.Moreover,we analyzed the inhibition mechanisms within different types of barium salts,namely BaCO_3 and Ba（OH）_2,on the thaumasite formation.The controlcement mortar and mortars with barium salts to cement and limestone weight ratios of 0.5%,1.0%,and 1.5% were immersed in 5%（by weight）MgSO_4 solution at 5 ℃ to mimic TSA.Appearance,mass,and compressive strength of the mortar samples were monitored and measured to assess the generaldegradation extent of these samples.The products of sulphate attack were further analyzed by XRD,FTIR,and SEM,respectively.Experimentalresults show that different degradation extent is evident in allmortars cured in MgSO_4 solution.However,barium salts can greatly inhibit such degradation.Barium in hydroxide form has better effectiveness in protection against TSA than carbonate form,which may be due to their solubility difference in alkaline cement pore solution,and the presence of these barium compounds can reduce the degree of TSA by comparison with the almost completely decomposed controlsamples.
文摘The isoplethic vapor-liquid equilibria(VLE)for N,N -dimethylformamide +2-propanol+1-propanol and their binary constituent mixtures were measured by using an inclined ebulliometer with a pump-like stirrer. The comparison between the experimental results and literature for binary systems was given. The ternary VLE were predicted by using modified UNIQUAC model with temperature-dependence binary parameters.
基金Acknowledgement This work is supported by the National Natural Science Foundation of China （No. 21173139）, the foundation of Shannxi Education Department （No. 2013JK0667）, and the foundation of Yanan University （No. YDQ2013-16）.
文摘The isomerization of CH3S（OH）CH2 to CH3S（O）CH3 in the absence and presence of water has been investigated at the G3XMP2//B3LYP/6-311 ＋ G（2df, p） level. The naked isomerization, the reaction without water, gives the high barrier height （21.56 kcal.mol^-1）. Three models are constructed to describe the water influence on the isomerization, that is, water molecules are the catalyst and the microsolvation, and water molecules act as the catalyst and microsolvation simultaneously. Our results show that the isomerization barrier heights of CH3S（OH）CH2 to CH3S（O）CH3 are reduced by 12.32, 11.04, and 7.80 kcal.mol^-1, respectively, when one, two, and three water molecules are performed as catalyst, in contrast to the naked isomerization. Moreover, the rate constants of the isomerization are calculated using the transition state theory with the Wigner tunneling correction over the temperature range of 240-425 K. We find that the rate constant of a single water molecule as the catalyst is 1.58 times larger than the naked isomerization at 325 K, whereas it is slower by 6 orders of magnitude when water molecule serves as the microsolvation at 325 K, compared to naked reaction. So the water-catalyzed isomerization of CH3S（OH）CH2 to CH3S（O）CH3 is predicted to be the key role in lowering the activation energy. The isomerization involving water molecules acting as mierosolvation is unfavorable under atmospheric conditions.
基金Zhejiang Provincial Natural Science Foundation of China,Grant/Award Number:LQ20B010002。
文摘Doping of foreign atoms and construction of unique structures are considered as effective approaches to design high-activity and strongdurability electrocatalysts.Herein,we report Fe-doped nickel hydroxide carbonate hierarchical microtubes with Ag nanoparticles(denoted Ag/NiFeHC HMTs)through hydrolysis precipitation process.Experimental tests and density functional theory calculations reveal that Fe doping can tune the electron configuration to enhance the conductivity,markedly improve the electrochemical surface area to expose more active sites,and act as reactive centers to lower the free energy of the rate determination step.In addition,the unique hierarchical structure can also offer active sites and excellent cycling stability.Benefitting from these advantages,the as-obtained Ag/NiFeHC HMTs show excellent oxygen evolution reaction activity,with an overpotential of 208 mV at 10 mA cm^(−2)in 1.0M KOH.Also,it could achieve long-term stability at a current density of 20 mA cm^(−2)for 24 h.
