Activated carbons were prepared by two chemical methods and the adsorption of Cu(II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activa...Activated carbons were prepared by two chemical methods and the adsorption of Cu(II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration,and p Hzpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also,adsorption mechanism and effect of p H on the adsorption of Cu(II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu(II) ions is stronger than that with H+ions due to relatively higher divalent charge or stronger electrostatic force.展开更多
Density‐functional theory calculations were carried out to study the strontium(Sr)‐doping effect on methane activation over a lanthanum‐oxide(La2O3)catalyst for the oxidative coupling of methane(OCM)using the clust...Density‐functional theory calculations were carried out to study the strontium(Sr)‐doping effect on methane activation over a lanthanum‐oxide(La2O3)catalyst for the oxidative coupling of methane(OCM)using the cluster model.Eight Sr‐doped La2O3cluster models were built from pure La2O3clusters that were used previously to model the La2O3catalyst.These form two distinct categories,namely,those without a radical character(LaSrO2(OH),La2SrO4,La3SrO5(OH),and La5SrO8(OH))and those with a radical character(LaSrO3,La2SrO4(OH),La3SrO6,and La5SrO9).The potential‐energy surface for CH4activation to form a CH3radical at different Sr-O and La-O pair sites on these Sr‐doped La2O3clusters was calculated to study the Sr‐doping effect on the OCM catalytic activity.CH4physisorption and chemisorption energies,and activation barriers,and CH3desorption energies were predicted.Compared with the pure La2O3clusters,in general,the Sr‐doped La2O3clusters are thermodynamically and kinetically more reactive with CH4.For the Sr‐doped La2O3clusters without the radical character,the Sr-O pair site is more reactive with CH4than the La-O pair site,although a direct release of the CH3radical is also highly endothermic as in the case of the pure La2O3clusters.In contrast,for the Sr‐doped La2O3clusters with a radical character,the activation of CH4at the oxygen radical site and the release of the CH3radical are much easier.Thus,our calculations suggest that the Sr dopant prompts the OCM catalytic activity of the La2O3catalyst by providing a highly active oxygen‐radical site and by strengthening the basicity of the M-O pair site,which leads to lower CH4activation energies and lower CH3desorption energies.展开更多
Accurate estimation of liquid thermal conductivity is highly necessary to appropriately design equipments in different industries. Respect to this necessity, in the current investigation a feed-forward artificial neur...Accurate estimation of liquid thermal conductivity is highly necessary to appropriately design equipments in different industries. Respect to this necessity, in the current investigation a feed-forward artificial neural network(ANN) model is examined to correlate the liquid thermal conductivity of normal and aromatic hydrocarbons at the temperatures range of 257–338 K and atmospheric pressure. For this purpose, 956 experimental thermal conductivities for normal and aromatic hydrocarbons are collected from different previously published literature.During the modeling stage, to discriminate different substances, critical temperature(Tc), critical pressure(Pc)and acentric factor(ω) are utilized as the network inputs besides the temperature. During the examination, effects of different transfer functions and number of neurons in hidden layer are investigated to find the optimum network architecture. Besides, statistical error analysis considering the results obtained from available correlations and group contribution methods and proposed neural network is performed to reliably check the feasibility and accuracy of the proposed method. Respect to the obtained results, it can be concluded that the proposed neural network consisted of three layers namely, input, hidden and output layers with 22 neurons in hidden layer was the optimum ANN model. Generally, the proposed model enables to correlate the thermal conductivity of normal and aromatic hydrocarbons with absolute average relative deviation percent(AARD), mean square error(MSE), and correlation coefficient(R^2) of lower than 0.2%, 1.05 × 10^(-7) and 0.9994, respectively.展开更多
To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve...To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging.In this work,a well-designed nanosheet-based rodlike step-scheme(S-scheme)heterojunction Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with rich oxygen vacancies(OVs)(Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2)-OV)was easily synthesized by calcining BiOAc0.6Br0.2I0.2(Ac-=CH3 COO-)precursor.The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline(TC)and dye rhodamine B(Rh B)degradation and removal rate reached 90.2% and 97.0%within 120 min,respectively,which was higher than those of Bi4O5I2-OV(56.8% and 71.8%),Bi4O5Br2-OV(47.4%and 68.4%),solid solution BiOAc0.6Br0.2I0.2(67.0% and 84.0%)and Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with poor oxygen vacancies(Bi4O5I2/Bi4O5Br2-P)(30.6%and 40.4%).Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac-,it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides,which thus decreased particle size and increased surface areas,but also introduce surface OVs,which could trap photoelectrons and inhibit the recombination of carriers.In addition,the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials,which facilitates charge carriers transfer at the interfaces.The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and Rh B in actual wastewater or in the presence of some electrolytes.This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.展开更多
Inhibition of 11βHSD1 （11-beta-hydroxysteroid dehydrogenase 1） is a promising strategy in drug treatment of diabetes. Several 11βHSDI inhibitors have been proposed; however, their selectivity to 11βHSD1 over its ...Inhibition of 11βHSD1 （11-beta-hydroxysteroid dehydrogenase 1） is a promising strategy in drug treatment of diabetes. Several 11βHSDI inhibitors have been proposed; however, their selectivity to 11βHSD1 over its isozyme 11βHSD2 （11-beta-hydroxysteroid dehydrogenase 2） has not been fully reported. The authors sought to provide a short list of top potent and selective compounds along with their detailed binding modes and pharmacophore models, Molecular docking was used for initial screening of a set of 23 potent inhibitors reported by previous experimental studies. After that, selected promising entries were reassessed by molecular dynamics simulations, followed by hydrogen bond analysis. Pharmacophore models of all drug candidates and binding modes of some selected drugs were analyzed. Among the 23 compounds, only four inhibitors were identified as potent and selective drug candidates. Binding energies, 3D pharmacophores and binding modes of the four compounds with 11βHSDI are also discussed in detail in this study.展开更多
In order to study the theoretical cycle characteristic of [mmim]DMP （1-methyl-3-methylimidazolium dimethyl- phosphate）/methanol absorption refrigeration, the modified UNIFAC group contribution model and the Wilson m...In order to study the theoretical cycle characteristic of [mmim]DMP （1-methyl-3-methylimidazolium dimethyl- phosphate）/methanol absorption refrigeration, the modified UNIFAC group contribution model and the Wilson model are established through correlating the experimental vapor pressure data of [mmim]DMP/methanol at T= 280~370 K and methanol mole fraction x= 0.529-0.965. Thermodynamic performances of absorption refrigera- tion utilizing [mmim]DMP/methanol, LiBr/H20 and H20/NH3 are investigated and compared with each other under the same operating conditions. From the results, some conclusions are obtained as follows： 1） the circula- tion ratio of the [mmim]DMP/methanol absorption refrigeration is higher than that of the LiBr/H2O absorption refrigeration, but still can be acceptable and tolerable. 2） The COP of the [mmim]DMP/methanol absorption refrigeration is smaller than that of the LiBr/H2O absorption refrigeration, while it is higher than that of the H2O/NH3 absorption refrigeration under most operating conditions. 3） The [mmim]DMP/methanol absorption refrigeration are still available with high COP when the heat source temperature is too high to drive LiBr/H2O absorption refrigeration.展开更多
Human intestinal carboxyl esterase （hiCE） is a drug target for ameliorating irinotecan-induced diarrhea. By reducing irinotecan- induced diarrhea, hiCE inhibitors can improve the anti-cancer efficacy of irinotecan. ...Human intestinal carboxyl esterase （hiCE） is a drug target for ameliorating irinotecan-induced diarrhea. By reducing irinotecan- induced diarrhea, hiCE inhibitors can improve the anti-cancer efficacy of irinotecan. To find effective hiCE inhibitors, a new virtual screening protocol that combines pharmacophore models derived from the hiCE structure and its ligands has been pro- posed. The hiCE structure has been constructed through homology techniques using hCESI＇s crystal structure. The hiCE structure was optimized via molecular dynamics simulations with the most known active hiCE inhibitors docked into the structure. An optimized pharmacophore, derived from the receptor, was then generated. A ligand-based pharmacophore was also generated from a larger set of known hiCE inhibitors. The final hiCE inhibitor predictions were based upon the virtual screening hits from both ligand-based and receptor-based pharmacophore models. The hit rates from the ligand-based and receptor-based pharmacophore models are 88% and 86%, respectively. The final hit rate is 94%. The two models are highly consistent with one another （85%）. This proves that both models are reliable.展开更多
文摘Activated carbons were prepared by two chemical methods and the adsorption of Cu(II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration,and p Hzpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also,adsorption mechanism and effect of p H on the adsorption of Cu(II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu(II) ions is stronger than that with H+ions due to relatively higher divalent charge or stronger electrostatic force.
基金supported by the National Natural Science Foundation of China(21473233,21403277)the Frontier Science Program of Shell Global Solutions International B.V.(PT32281)+1 种基金the Ministry of Science and Technology of China(2016YFA0202802)the Shanghai Municipal Science and Technology Commission(14ZR1444600)~~
文摘Density‐functional theory calculations were carried out to study the strontium(Sr)‐doping effect on methane activation over a lanthanum‐oxide(La2O3)catalyst for the oxidative coupling of methane(OCM)using the cluster model.Eight Sr‐doped La2O3cluster models were built from pure La2O3clusters that were used previously to model the La2O3catalyst.These form two distinct categories,namely,those without a radical character(LaSrO2(OH),La2SrO4,La3SrO5(OH),and La5SrO8(OH))and those with a radical character(LaSrO3,La2SrO4(OH),La3SrO6,and La5SrO9).The potential‐energy surface for CH4activation to form a CH3radical at different Sr-O and La-O pair sites on these Sr‐doped La2O3clusters was calculated to study the Sr‐doping effect on the OCM catalytic activity.CH4physisorption and chemisorption energies,and activation barriers,and CH3desorption energies were predicted.Compared with the pure La2O3clusters,in general,the Sr‐doped La2O3clusters are thermodynamically and kinetically more reactive with CH4.For the Sr‐doped La2O3clusters without the radical character,the Sr-O pair site is more reactive with CH4than the La-O pair site,although a direct release of the CH3radical is also highly endothermic as in the case of the pure La2O3clusters.In contrast,for the Sr‐doped La2O3clusters with a radical character,the activation of CH4at the oxygen radical site and the release of the CH3radical are much easier.Thus,our calculations suggest that the Sr dopant prompts the OCM catalytic activity of the La2O3catalyst by providing a highly active oxygen‐radical site and by strengthening the basicity of the M-O pair site,which leads to lower CH4activation energies and lower CH3desorption energies.
文摘Accurate estimation of liquid thermal conductivity is highly necessary to appropriately design equipments in different industries. Respect to this necessity, in the current investigation a feed-forward artificial neural network(ANN) model is examined to correlate the liquid thermal conductivity of normal and aromatic hydrocarbons at the temperatures range of 257–338 K and atmospheric pressure. For this purpose, 956 experimental thermal conductivities for normal and aromatic hydrocarbons are collected from different previously published literature.During the modeling stage, to discriminate different substances, critical temperature(Tc), critical pressure(Pc)and acentric factor(ω) are utilized as the network inputs besides the temperature. During the examination, effects of different transfer functions and number of neurons in hidden layer are investigated to find the optimum network architecture. Besides, statistical error analysis considering the results obtained from available correlations and group contribution methods and proposed neural network is performed to reliably check the feasibility and accuracy of the proposed method. Respect to the obtained results, it can be concluded that the proposed neural network consisted of three layers namely, input, hidden and output layers with 22 neurons in hidden layer was the optimum ANN model. Generally, the proposed model enables to correlate the thermal conductivity of normal and aromatic hydrocarbons with absolute average relative deviation percent(AARD), mean square error(MSE), and correlation coefficient(R^2) of lower than 0.2%, 1.05 × 10^(-7) and 0.9994, respectively.
文摘To improve separation efficiency of the photogenerated electron-hole pairs,constructing a heterojunction is considered to be a promising strategy.However,the fabrication of heterojunction via a facile route to achieve a substantial improvement in photocatalytic performance is still challenging.In this work,a well-designed nanosheet-based rodlike step-scheme(S-scheme)heterojunction Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with rich oxygen vacancies(OVs)(Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2)-OV)was easily synthesized by calcining BiOAc0.6Br0.2I0.2(Ac-=CH3 COO-)precursor.The as-prepared Bi4O5I2/Bi4O5Br2-OV exhibited excellent visible light photocatalytic performance towards antibiotic tetracycline(TC)and dye rhodamine B(Rh B)degradation and removal rate reached 90.2% and 97.0%within 120 min,respectively,which was higher than those of Bi4O5I2-OV(56.8% and 71.8%),Bi4O5Br2-OV(47.4%and 68.4%),solid solution BiOAc0.6Br0.2I0.2(67.0% and 84.0%)and Bi_(4)O_(5)I_(2)/Bi_(4)O_(5)Br_(2) with poor oxygen vacancies(Bi4O5I2/Bi4O5Br2-P)(30.6%and 40.4%).Owing to the release of heat and generation of reducing carbon during calcining the precursor with Ac-,it could not only reduce the generation temperature of Bi-rich bismuth oxyhalides,which thus decreased particle size and increased surface areas,but also introduce surface OVs,which could trap photoelectrons and inhibit the recombination of carriers.In addition,the calcination of single solid solution precursor benefited to the formation of well-alloyed interfaces with larger contact areas between 2D/2D nanosheet-like materials,which facilitates charge carriers transfer at the interfaces.The Bi4O5I2/Bi4O5Br2-OV also shows the desirable removal rate for TC and Rh B in actual wastewater or in the presence of some electrolytes.This study provides an effective and simple strategy for designing OVs modified Bi-rich oxyhalides heterojunctions.
文摘Inhibition of 11βHSD1 （11-beta-hydroxysteroid dehydrogenase 1） is a promising strategy in drug treatment of diabetes. Several 11βHSDI inhibitors have been proposed; however, their selectivity to 11βHSD1 over its isozyme 11βHSD2 （11-beta-hydroxysteroid dehydrogenase 2） has not been fully reported. The authors sought to provide a short list of top potent and selective compounds along with their detailed binding modes and pharmacophore models, Molecular docking was used for initial screening of a set of 23 potent inhibitors reported by previous experimental studies. After that, selected promising entries were reassessed by molecular dynamics simulations, followed by hydrogen bond analysis. Pharmacophore models of all drug candidates and binding modes of some selected drugs were analyzed. Among the 23 compounds, only four inhibitors were identified as potent and selective drug candidates. Binding energies, 3D pharmacophores and binding modes of the four compounds with 11βHSDI are also discussed in detail in this study.
基金supported by the National Basic Research Program of China (973 Program) under Grant No.2012CB933200the National Natural Science Fundation of China under Grant No.51276180
文摘In order to study the theoretical cycle characteristic of [mmim]DMP （1-methyl-3-methylimidazolium dimethyl- phosphate）/methanol absorption refrigeration, the modified UNIFAC group contribution model and the Wilson model are established through correlating the experimental vapor pressure data of [mmim]DMP/methanol at T= 280~370 K and methanol mole fraction x= 0.529-0.965. Thermodynamic performances of absorption refrigera- tion utilizing [mmim]DMP/methanol, LiBr/H20 and H20/NH3 are investigated and compared with each other under the same operating conditions. From the results, some conclusions are obtained as follows： 1） the circula- tion ratio of the [mmim]DMP/methanol absorption refrigeration is higher than that of the LiBr/H2O absorption refrigeration, but still can be acceptable and tolerable. 2） The COP of the [mmim]DMP/methanol absorption refrigeration is smaller than that of the LiBr/H2O absorption refrigeration, while it is higher than that of the H2O/NH3 absorption refrigeration under most operating conditions. 3） The [mmim]DMP/methanol absorption refrigeration are still available with high COP when the heat source temperature is too high to drive LiBr/H2O absorption refrigeration.
基金funded in part of the National High-tech R&D Program of China(863 Program)(2012AA020307)the introduction of innovative R&D team program of Guangdong Province(2009010058)+1 种基金the National Natural Science Foundation of China(81001372,81173470)the Fundamental Research Funds for the Central Universities(10ykjc01)
文摘Human intestinal carboxyl esterase （hiCE） is a drug target for ameliorating irinotecan-induced diarrhea. By reducing irinotecan- induced diarrhea, hiCE inhibitors can improve the anti-cancer efficacy of irinotecan. To find effective hiCE inhibitors, a new virtual screening protocol that combines pharmacophore models derived from the hiCE structure and its ligands has been pro- posed. The hiCE structure has been constructed through homology techniques using hCESI＇s crystal structure. The hiCE structure was optimized via molecular dynamics simulations with the most known active hiCE inhibitors docked into the structure. An optimized pharmacophore, derived from the receptor, was then generated. A ligand-based pharmacophore was also generated from a larger set of known hiCE inhibitors. The final hiCE inhibitor predictions were based upon the virtual screening hits from both ligand-based and receptor-based pharmacophore models. The hit rates from the ligand-based and receptor-based pharmacophore models are 88% and 86%, respectively. The final hit rate is 94%. The two models are highly consistent with one another （85%）. This proves that both models are reliable.
