The reaction mechanism of 1-chloroethane with hydroxyl radical has been investigated by using density functional theory （DFT） B3LYP/6-31G （d, p） method. All bond dissociation enthalpies were computed at the same t...The reaction mechanism of 1-chloroethane with hydroxyl radical has been investigated by using density functional theory （DFT） B3LYP/6-31G （d, p） method. All bond dissociation enthalpies were computed at the same theoretical level. It was found that hydrogen abstraction pathway is the most favorable. There are two hydrogen abstraction pathways with activation barriers of 0.630 and 4.988 kJ/mol, respectively, while chlorine abstraction pathway was not found. It was observed that activation energies have a more reasonable correlation with the reaction enthalpy changes （ΔHr） than with bond dissociation enthalpies （BDE）.展开更多
The kinetics of forward extraction of Ti（IV） from H2SO4 medium by P507 in kerosene has been investigated using the single drop technique.In the low concentration region of Ti（IV）,the rate of forward extraction at ...The kinetics of forward extraction of Ti（IV） from H2SO4 medium by P507 in kerosene has been investigated using the single drop technique.In the low concentration region of Ti（IV）,the rate of forward extraction at 298 K can be represented by F（kmol·m-2·s-1）=10-5.07 [TiO 2 ＋ ][H＋]-1 [NaHA 2 ]（o）·Analysis of the rate expression reveals that the rate determining step is（TiO）（i）2＋ ＋（HA 2）（i）-[TiO（HA2）]（i）＋.The values of Ea,H±,S±,and G±298 are calculated to be 22 kJ·mol-1,25 kJ·mol-1,-218 J·mol-1·K-1,and 25 kJ·mol-1,respectively.The experimental negative S± values indicate that the reaction step occurs via SN2 mechanism.展开更多
Soil phosphomonoesterase plays a critical role in controlling phosphorus(P) cycling for crop nutrition,especially in P-deficient soils.A 6-year field experiment was conducted to evaluate soil phosphomonoesterase activ...Soil phosphomonoesterase plays a critical role in controlling phosphorus(P) cycling for crop nutrition,especially in P-deficient soils.A 6-year field experiment was conducted to evaluate soil phosphomonoesterase activities,kinetics and thermodynamics during rice growth stages after consistent swine manure application,to understand the impacts of swine manure amendment rates on soil chemical and enzymatic properties,and to investigate the correlations between soil enzymatic and chemical variables.The experiment was set out in a randomized complete block design with three replicates and five treatments including three swine manure rates(26,39,and 52 kg P ha^(-1),representing low,middle,and high application rates,respectively) and two controls(no-fertilizer and superphosphate at 26 kg P ha^(-1)).The results indicated that the grain yield and soil chemical properties were significantly improved with the application of P-based swine manure from 0 to 39 kg P ha^(-1);however,the differences between the 39(M_(39)) and 52 kg P ha^(-1) treatments(M_(52)) were not significant.The enzymatic property analysis indicated that acid phosphomonoesterase was the predominant phosphomonoesterase in the tested soil.The M_(39) and M_(52) treatments had relatively high initial velocity(V_0),maximal velocity(V_(max)),and activation grade(lgN_a) but low Michaelis constant(K_m),temperature coefficient(Q_(10)),activation energy(E_a),and activation enthalpy(ΔH),implying that the M_(39) and M_(52) treatments could stimulate the enzyme-catalyzed reactions more easily than all other treatments.The correlation analysis showed that the distribution of soil phosphomonoesterase activities mainly followed the distributions of total C and total N.Based on these results,39 kg P ha^(-1) could be recommended as the most appropriate rate of swine manure amendment.展开更多
The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-u...The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature, indicating endothermic ion exchange reactions. From the K values calculated at different temperatures the enthalpy values were calculated. The low enthalpy and higher K values for K+ ion ex-change reaction indicates more affinity of the resin for potassium ions as compared to that for sodium ions also in the solution. The technique used in the present experimental work will be useful in understanding the selectivity behav-iour of different ion exchange resins for ions in the solution. Although the ionic selectivity data for the ion exchange resins is readily available in the literature, it is expected that the informa-tion obtained from the actual experimental trials will be more helpful. The technique used in the present experimental work when applied to dif-ferent ion exchange resins will help in there characterization.展开更多
An increase of carbon dioxide content accompanied by an increase of the temperature is observed in the atmosphere during the last 200 years. This behaviour can be explained by examination of correlations between tree ...An increase of carbon dioxide content accompanied by an increase of the temperature is observed in the atmosphere during the last 200 years. This behaviour can be explained by examination of correlations between tree generally accepted data sets of the recent past, world population, carbon dioxide content in the atmosphere, and rise of global temperature as function of time. No return to climate situations from hundred thousand of years before present is necessary. The world climate is a dynamic equilibrium between all energy generating processes on earth, especially sun energy, and the radiation of energy into space. Since approx. 200 years the dynamic equilibrium is changed additionally by means of fossil energy carriers, whose depots were put on in passed geological epochs, a climatic disturbance was produced. It is shown that the consumption of energy per year by the mankind can warm up the atmosphere by about one degree. This quantity cannot be neglected in climatic calculations;therefore it is the cause of mankind made warming of the atmosphere. The qualitative analyses presented here have shown that the use of so-called renewable energy sources does not necessarily lead to the avoidance of global warming. It can be expected that some techniques will have no or even small effect. Especially the model calculations to the operation of wind turbines and its influence on the temperature of the atmosphere show that it is difficult to estimate their influence and cannot be foreknown.展开更多
A comprehensive theoretical study on the bimolecular reaction of C2H502 with OH radicals was performed at the CCSD（T）/6-311＋＋G（2df2p）//B3LYP/6-311＋G（d,p） level of theory. The calculation results show that C2H...A comprehensive theoretical study on the bimolecular reaction of C2H502 with OH radicals was performed at the CCSD（T）/6-311＋＋G（2df2p）//B3LYP/6-311＋G（d,p） level of theory. The calculation results show that C2H5O2 ＋ OH reaction proceeds on both the singlet and the triplet potential energy surfaces（PESs）. On the singlet PES, the favorable pathway is the addition of OH radical to the terminal oxygen atom of C2H5O2 radical, leading to the formation of trioxide C2H5O3H with a barrierless process. Then, the trioxide directly decomposes to the products C2H50 and HO2 radicals. On the triplet PES, the predominant pathways are a and β hydrogen atom abstractions of C2H5O2 radical by OH radical-forming products 3CH3CHO2＋H2O and 3CH2CH2O2＋H2O, and the corresponding bar- tiers are 12.02（3TS8） and 19.19 kJ/mol（3TS9）, respectively. In addition, the comprehensive properties of trioxide C2H503H were investigated for the ftrst time. The results indicate that the trioxide complex RC1 can exist stably in the atmosphere owing to a significantly large and negative enthalpy of formation（-118.44 kJ/mol） as well as a high first excitation energy（5.94 eV）.展开更多
基金This work was supported by the grants from NSFC Foundations (No. 20473090 and 20633070) Foundation from Harbin Normal University (KM2005-02)
文摘The reaction mechanism of 1-chloroethane with hydroxyl radical has been investigated by using density functional theory （DFT） B3LYP/6-31G （d, p） method. All bond dissociation enthalpies were computed at the same theoretical level. It was found that hydrogen abstraction pathway is the most favorable. There are two hydrogen abstraction pathways with activation barriers of 0.630 and 4.988 kJ/mol, respectively, while chlorine abstraction pathway was not found. It was observed that activation energies have a more reasonable correlation with the reaction enthalpy changes （ΔHr） than with bond dissociation enthalpies （BDE）.
基金supported by the Key Subject of Shanghai Municipality (S30109)the Opening Project of Key Laboratory of Solid Waste Treatment and Resource Recycle (SWUST),the Ministry of Education (09zxgk02)Research Program of Science and Technology Commission of Shanghai Municipality (09dz1204403)
文摘The kinetics of forward extraction of Ti（IV） from H2SO4 medium by P507 in kerosene has been investigated using the single drop technique.In the low concentration region of Ti（IV）,the rate of forward extraction at 298 K can be represented by F（kmol·m-2·s-1）=10-5.07 [TiO 2 ＋ ][H＋]-1 [NaHA 2 ]（o）·Analysis of the rate expression reveals that the rate determining step is（TiO）（i）2＋ ＋（HA 2）（i）-[TiO（HA2）]（i）＋.The values of Ea,H±,S±,and G±298 are calculated to be 22 kJ·mol-1,25 kJ·mol-1,-218 J·mol-1·K-1,and 25 kJ·mol-1,respectively.The experimental negative S± values indicate that the reaction step occurs via SN2 mechanism.
基金supported by the National Natural Science Foundation of China(Nos.21077088,41271314and 51008107)
文摘Soil phosphomonoesterase plays a critical role in controlling phosphorus(P) cycling for crop nutrition,especially in P-deficient soils.A 6-year field experiment was conducted to evaluate soil phosphomonoesterase activities,kinetics and thermodynamics during rice growth stages after consistent swine manure application,to understand the impacts of swine manure amendment rates on soil chemical and enzymatic properties,and to investigate the correlations between soil enzymatic and chemical variables.The experiment was set out in a randomized complete block design with three replicates and five treatments including three swine manure rates(26,39,and 52 kg P ha^(-1),representing low,middle,and high application rates,respectively) and two controls(no-fertilizer and superphosphate at 26 kg P ha^(-1)).The results indicated that the grain yield and soil chemical properties were significantly improved with the application of P-based swine manure from 0 to 39 kg P ha^(-1);however,the differences between the 39(M_(39)) and 52 kg P ha^(-1) treatments(M_(52)) were not significant.The enzymatic property analysis indicated that acid phosphomonoesterase was the predominant phosphomonoesterase in the tested soil.The M_(39) and M_(52) treatments had relatively high initial velocity(V_0),maximal velocity(V_(max)),and activation grade(lgN_a) but low Michaelis constant(K_m),temperature coefficient(Q_(10)),activation energy(E_a),and activation enthalpy(ΔH),implying that the M_(39) and M_(52) treatments could stimulate the enzyme-catalyzed reactions more easily than all other treatments.The correlation analysis showed that the distribution of soil phosphomonoesterase activities mainly followed the distributions of total C and total N.Based on these results,39 kg P ha^(-1) could be recommended as the most appropriate rate of swine manure amendment.
文摘The selectivity behaviour of ion exchange resin Amberlite IR-120 for inorganic cations like sodium and potassium was predicted on the basis of thermodynamic data. The equilibrium constant K values calculated for uni-univalent ion exchange reaction systems were observed to increase with rise in temperature, indicating endothermic ion exchange reactions. From the K values calculated at different temperatures the enthalpy values were calculated. The low enthalpy and higher K values for K+ ion ex-change reaction indicates more affinity of the resin for potassium ions as compared to that for sodium ions also in the solution. The technique used in the present experimental work will be useful in understanding the selectivity behav-iour of different ion exchange resins for ions in the solution. Although the ionic selectivity data for the ion exchange resins is readily available in the literature, it is expected that the informa-tion obtained from the actual experimental trials will be more helpful. The technique used in the present experimental work when applied to dif-ferent ion exchange resins will help in there characterization.
文摘An increase of carbon dioxide content accompanied by an increase of the temperature is observed in the atmosphere during the last 200 years. This behaviour can be explained by examination of correlations between tree generally accepted data sets of the recent past, world population, carbon dioxide content in the atmosphere, and rise of global temperature as function of time. No return to climate situations from hundred thousand of years before present is necessary. The world climate is a dynamic equilibrium between all energy generating processes on earth, especially sun energy, and the radiation of energy into space. Since approx. 200 years the dynamic equilibrium is changed additionally by means of fossil energy carriers, whose depots were put on in passed geological epochs, a climatic disturbance was produced. It is shown that the consumption of energy per year by the mankind can warm up the atmosphere by about one degree. This quantity cannot be neglected in climatic calculations;therefore it is the cause of mankind made warming of the atmosphere. The qualitative analyses presented here have shown that the use of so-called renewable energy sources does not necessarily lead to the avoidance of global warming. It can be expected that some techniques will have no or even small effect. Especially the model calculations to the operation of wind turbines and its influence on the temperature of the atmosphere show that it is difficult to estimate their influence and cannot be foreknown.
基金Supported by the National Natural Science Foundation of China（Nos.21473108, 21473107） and the Fundamental Research Funds for the Central Universities of China（No.GK201603035）.
文摘A comprehensive theoretical study on the bimolecular reaction of C2H502 with OH radicals was performed at the CCSD（T）/6-311＋＋G（2df2p）//B3LYP/6-311＋G（d,p） level of theory. The calculation results show that C2H5O2 ＋ OH reaction proceeds on both the singlet and the triplet potential energy surfaces（PESs）. On the singlet PES, the favorable pathway is the addition of OH radical to the terminal oxygen atom of C2H5O2 radical, leading to the formation of trioxide C2H5O3H with a barrierless process. Then, the trioxide directly decomposes to the products C2H50 and HO2 radicals. On the triplet PES, the predominant pathways are a and β hydrogen atom abstractions of C2H5O2 radical by OH radical-forming products 3CH3CHO2＋H2O and 3CH2CH2O2＋H2O, and the corresponding bar- tiers are 12.02（3TS8） and 19.19 kJ/mol（3TS9）, respectively. In addition, the comprehensive properties of trioxide C2H503H were investigated for the ftrst time. The results indicate that the trioxide complex RC1 can exist stably in the atmosphere owing to a significantly large and negative enthalpy of formation（-118.44 kJ/mol） as well as a high first excitation energy（5.94 eV）.
