The present study summarizes the results of macro-and micro-mixing characteristics in an airlift internal loop reactor with low aspect ratio(H/D≤5) using the electrolytic tracer response technique and the method of p...The present study summarizes the results of macro-and micro-mixing characteristics in an airlift internal loop reactor with low aspect ratio(H/D≤5) using the electrolytic tracer response technique and the method of parallel competing reactions respectively. The micro-mixing has never been investigated in airlift loop reactors. The dual-tip electrical conductivity probe technique is used for measurement of local bubble behavior in the reactor. The effects of several operating parameters and geometric variables are investigated. It is found that the increase in superficial gas velocity corresponds to the increase in energy input, liquid circulation velocity and shear rate, decreasing the macro-mixing time and segregation index. Moreover, it is shown that top clearance and draft diameter affect flow resistance. However, the bubble redistribution with a screen mesh on the perforated plate distributor for macro-mixing is insignificant. The top region with a high energy dissipation rate is a suitable location for feeding reactants. The analysis of present experimental data provides a valuable insight into the interaction between gas and liquid phases for mixing and improves the understanding of intrinsic roles of hydrodynamics upon the reactor design and operating parameter selection.展开更多
The first cyclic molecule formation reactions from ethyne （C2H2）, initiated by ethynyl radical （C2H）, were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-...The first cyclic molecule formation reactions from ethyne （C2H2）, initiated by ethynyl radical （C2H）, were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-arrangement for the favourable ring-closure mechanism and ethyne addition in each step. The analysis was done by evaluating the energy difference of activation （AE）, entalphy （AH）, Gibbs （AG） of the optimized stable and transition molecules. The reaction temperatures were set at normal （T = 298 K） and combustion （T = 1200 K） condition.展开更多
Invasive alien plants not only decrease riparian vegetation diversity but also alter wetland ecosystem carbon processes,especially when they displace the original vegetation.Invasive Canada goldenrod(Solidago canadens...Invasive alien plants not only decrease riparian vegetation diversity but also alter wetland ecosystem carbon processes,especially when they displace the original vegetation.Invasive Canada goldenrod(Solidago canadensis L.)has colonized large areas of disturbed and undisturbed land in southeastern China,yet little is known regarding how it affects soil carbon cycling.To explore the response patterns of soil respiration following S.canadensis invasion and their driving mechanisms,an observational field study and a greenhouse experiment simulating invasion were performed.In the field study,soil respiration was measured weekly from 21th July 2018 to 15th December 2018.In the greenhouse experiment,soil,autotrophic and heterotrophic respiration were measured every 1st and 15th of the month from 15th July 2019 to 15th December 2019.Soil,autotrophic and heterotrophic respiration were measured using a closed-chamber system with the deep gauze collar root exclusion method.Solidago canadensis invasion appeared to decrease the total soil CO_(2) emissions in both the field study and the greenhouse experiment.The suppressive effects on soil respiration may be attributed to S.canadensis invasion-induced alterations in the quality and quantity of available soil substrate,suggesting that S.canadensis invasion may impact soil carbon cycling via plant-released substrates and by competing for the soil available substrate with native plant and/or soil microbes.These results have substantial implications for estimations of the effects of invasive plants on belowground carbon dynamics and their contribution to the warming world.展开更多
基金Supported by the National Basic Research Program of China(2012CB224806)the National Science Fund for Distinguished Young Scholars(21025627)+2 种基金the National Natural Science Foundation of China(21206166,20990224)the National High Technology Research and Development Program of China(2012AA03A606)Beijing Natural Science Foundation(2112038)
文摘The present study summarizes the results of macro-and micro-mixing characteristics in an airlift internal loop reactor with low aspect ratio(H/D≤5) using the electrolytic tracer response technique and the method of parallel competing reactions respectively. The micro-mixing has never been investigated in airlift loop reactors. The dual-tip electrical conductivity probe technique is used for measurement of local bubble behavior in the reactor. The effects of several operating parameters and geometric variables are investigated. It is found that the increase in superficial gas velocity corresponds to the increase in energy input, liquid circulation velocity and shear rate, decreasing the macro-mixing time and segregation index. Moreover, it is shown that top clearance and draft diameter affect flow resistance. However, the bubble redistribution with a screen mesh on the perforated plate distributor for macro-mixing is insignificant. The top region with a high energy dissipation rate is a suitable location for feeding reactants. The analysis of present experimental data provides a valuable insight into the interaction between gas and liquid phases for mixing and improves the understanding of intrinsic roles of hydrodynamics upon the reactor design and operating parameter selection.
文摘The first cyclic molecule formation reactions from ethyne （C2H2）, initiated by ethynyl radical （C2H）, were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-arrangement for the favourable ring-closure mechanism and ethyne addition in each step. The analysis was done by evaluating the energy difference of activation （AE）, entalphy （AH）, Gibbs （AG） of the optimized stable and transition molecules. The reaction temperatures were set at normal （T = 298 K） and combustion （T = 1200 K） condition.
基金State Key Research Development Program of China(2017YFC1200100)the NationalNatural Science Foundation of China(31800342,31770446,32071521)+4 种基金the China Postdoctoral Science Foundation(2019M651720)the Talent Project from the Double Entrepreneurial Plan in Jiangsu Provincethe Jiangsu University Foundationthe Postgraduate Research and Practice InnovationProgram of Jiangsu Province(SJCX19.0568).
文摘Invasive alien plants not only decrease riparian vegetation diversity but also alter wetland ecosystem carbon processes,especially when they displace the original vegetation.Invasive Canada goldenrod(Solidago canadensis L.)has colonized large areas of disturbed and undisturbed land in southeastern China,yet little is known regarding how it affects soil carbon cycling.To explore the response patterns of soil respiration following S.canadensis invasion and their driving mechanisms,an observational field study and a greenhouse experiment simulating invasion were performed.In the field study,soil respiration was measured weekly from 21th July 2018 to 15th December 2018.In the greenhouse experiment,soil,autotrophic and heterotrophic respiration were measured every 1st and 15th of the month from 15th July 2019 to 15th December 2019.Soil,autotrophic and heterotrophic respiration were measured using a closed-chamber system with the deep gauze collar root exclusion method.Solidago canadensis invasion appeared to decrease the total soil CO_(2) emissions in both the field study and the greenhouse experiment.The suppressive effects on soil respiration may be attributed to S.canadensis invasion-induced alterations in the quality and quantity of available soil substrate,suggesting that S.canadensis invasion may impact soil carbon cycling via plant-released substrates and by competing for the soil available substrate with native plant and/or soil microbes.These results have substantial implications for estimations of the effects of invasive plants on belowground carbon dynamics and their contribution to the warming world.
