A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring sp...A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring speed on vanadium and chromium extraction were studied. The results suggest that the reaction temperature and KOH-to-ore mass ratio are more influential factors for the extraction of vanadium and chromium. Under the optimal reaction conditions （temperature 180 °C, initial KOH-to-ore mass ratio 4：1, stirring speed 700 r/min, gas flow 1 L/min, and reaction time 300 min）, vanadium and chromium extraction rates can reach up to 95% and 90%, respectively. Kinetics analysis results show that the decomposing process of vanadium slag in KOH sub-molten salt can be well interpreted by the shrinking core model under internal diffusion control. The apparent activation energies for vanadium and chromium are 40.54 and 50.27 kJ/mol, respectively.展开更多
The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reacti...The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reaction of La^(3+),Gd^(3+)and Ho^(3+)with TBA were studied.It is shown in the study that prerequisites for performing differential rate analysis for binary rare earths with TBA are that the pseudo-first-order parallel reaction mechanism should be conformed with,no multinuclear complex would be formed and the co-coloration effects could be neglected.展开更多
The kinetic behaviours of the substitution reaction of rare earth-PHA with CyDTA were studied systemati- cally.The relationship between the rate constant and atomic number was discussed.The rate differentiation val- u...The kinetic behaviours of the substitution reaction of rare earth-PHA with CyDTA were studied systemati- cally.The relationship between the rate constant and atomic number was discussed.The rate differentiation val- ue R_d(R_d=lgk_(z+n)-lgk_z)was proposed to evaluate the possibility of differential kinetic analysis.The R_d value between the neighbouring lanthanide ions first increases and then decreases along with increasing atomic number, so that the middle and heavy rare earth mixture(such as Sm-Gd and Gd-Y)are ideal systems for the differential rate kinetic analysis.展开更多
The effects of long-term moisture changes on the migration,release,and bioavailability of selenium in soil are complex.Due to the lack of effective monitoring methods for precise quantification,its dynamic behavior is...The effects of long-term moisture changes on the migration,release,and bioavailability of selenium in soil are complex.Due to the lack of effective monitoring methods for precise quantification,its dynamic behavior is still unclear.Based on the DGT(Diffusive Gradients in Thin-films)technology,this study sets up three moisture control scenarios:continuous wet,wet-dry alternating,and continuous dry,and carries out a 6-month soil moisture control experiment.In the experiment,the DGT device collected the diffusion gradient data of soil selenium under different scenarios,and analyzed the migration characteristics of selenium in combination with the adsorption isotherm.Meanwhile,the release rate,migration coefficient,and bioavailability parameters of selenium are calculated by fitting the first-order kinetic model,further verifying the reliability and applicability of the DGT data.The experimental results demonstrate that under continuous wet conditions,the release rate of soil selenium reaches 1.85µg·cm^(-2)·h^(-1),with a migration coefficient of 0.012 cm^(2)·h^(-1)and a bioavailability parameter of 0.74;under wet-dry alternating conditions,they are 1.42µg·cm^(-2)·h^(-1),0.01 cm^(2)·h^(-1),and 0.68,respectively;under continuous dry conditions,the release rate of soil selenium is the smallest,at 0.88µg·cm^(-2)·h^(-1),with a migration coefficient of 0.004 cm^(-2)·h^(-1)and a bioavailability parameter of 0.5.The results of this experiment reveal the dynamic behavior of soil selenium under different moisture conditions and reflect the high efficiency of DGT technology in dynamic monitoring and quantitative analysis of soil selenium behavior,providing a scientific basis for the optimal management of rhizosphere soil selenium.展开更多
This study prepared a class of RDX-based composite microspheres(RAF)containing ADN and FKM2602.The reaction kinetics of RAF composite microspheres were effectively improved by maintaining the system's high energy ...This study prepared a class of RDX-based composite microspheres(RAF)containing ADN and FKM2602.The reaction kinetics of RAF composite microspheres were effectively improved by maintaining the system's high energy and safety performance.In the close packing state,when the heating rate is rapid,the thermal stability of RAF composite microspheres is better than that of RDX;the close packing state will reduce the degree of freedom of RDX and ADN reaction but will increase the degree of freedom of RAF composite microsphere reaction.The thermal conductivity of RAF composite microspheres is close to that of RDX.In the ignition experiment,the flame of RAF composite microspheres can be maintained without the external heat source.Regarding safety,the H50of RAF composite microspheres was 274.04%higher than that of RDX.The detonation velocity of RAF composite microspheres is slightly higher than that of raw material RDX.Overall,these findings highlight the effectiveness of ADN in enhancing the reaction kinetics of RDX-based composites.展开更多
The purity of the brazing alloys applied is necessary to be improved with the increasing cleanness of steel. Calcium is easily brought into the widely ased brazing alloy, Ag-Cu-Zn, during the producing process. This p...The purity of the brazing alloys applied is necessary to be improved with the increasing cleanness of steel. Calcium is easily brought into the widely ased brazing alloy, Ag-Cu-Zn, during the producing process. This paper aims at revealing the effect of calcium on the melting behavior of the brazing alloy. The thermal analysis kinetics of silver alloy with trace calcium was studied by using differential scanning calorimetry （ DSC ） , and the enthalpy peaks were analyzed by differential methods. The rate constant of phase transformation in the probable brazing temperature range goes up with increasing calcium content, according to the values of the apparent activation energy, E, and the frequeney constant, A. It is concluded that the calcium addition could improve the melting performance of Ag-Cu-Zn brazing alloy.展开更多
The large accumulation of coal gangue,a common industrial solid waste,causes severe environmental problems,and green development strategies are required to transform this waste into high-value-added products.In this s...The large accumulation of coal gangue,a common industrial solid waste,causes severe environmental problems,and green development strategies are required to transform this waste into high-value-added products.In this study,low-cost ceramsites adsorbents were prepared from waste gangue,silt coal,and peanut shells and applied to remove the organic dye methylene blue from wastewater.We investigated the microstructure of ceramsites and the effects of the sintering atmosphere,sintering temperature,and solution pH on their adsorption performance.The ceramsites sintered at 800℃under a nitrogen atmosphere exhibited the largest three-dimensional-interconnected hierarchical porous structure among the prepared ceramsites;further,it exhibited the highest methylene blue adsorption performance,with an adsorption capacity of 0.954 mg·g^(−1),adsorption efficiency of over 95%,and adsorption equilibrium time of 1 h at a solution pH of 9.The removal efficiency remained greater than 75%after five adsorption cycles.The adsorption kinetics data were analyzed using various models,including the pseudosecond-order kinetic model and Langmuir equation,and the adsorption was attributed to electrostatic interactions between the dyes and ceramsites,n-interactions,and hydrogen bonds.The prepared coal gangue ceramsites exhibited excellent adsorption capacities,removal rates,and cyclic stabilities,demonstrating their promising application prospects for the comprehensive utilization of solid waste and for wastewater treatment.展开更多
In the conversion of methane and propane under high temperature and pressure,the ignition delay time(IDT)is a key parameter to consider for designing an inherently safe process.In this study,the IDT characteristics of...In the conversion of methane and propane under high temperature and pressure,the ignition delay time(IDT)is a key parameter to consider for designing an inherently safe process.In this study,the IDT characteristics of methane and propane(700–1000 K,10–20 bar)were studied experimentally and using kinetic modeling tools at stoichiometric fuel-tooxygen ratios.All the experiments were conducted through insentropic compression.The reliable experimental data were obtained by using the adiabatic core hypothesis,which can be used to generate and validate the detailed chemical kinetics model.The IDTs of methane and propane were recorded by a rapid compression machine(RCM)and compared to the predicted values obtained by the NUIGMech 3.0 mechanism.To test the applicability of NUIGMech 3.0 under different reaction conditions,the influence of temperature in the range of 700–1000 K(and the influence of pressure in the range of 10–20 bar)on the IDT was studied.The results showed that NUIGMech 3.0 could reasonably reproduce the experimentally determined IDT under the wide range of conditions studied.The constant volume chemical kinetics model was used to reveal the effect of temperature on the elementary reaction,and the negative temperature coefficient(NTC)behavior of propane was also observed at 20 bar.The experimental data can serve as a reference for the correction and application of kinetic data,as well as provide a theoretical basis for the safe conversion of low-carbon hydrocarbon chemicals.展开更多
The synthesis of carbide coatings on graphite substrates using molten salt synthesis(MSS),has garnered significant interest due to its cost-effective nature.This study investigates the reaction process and growth kine...The synthesis of carbide coatings on graphite substrates using molten salt synthesis(MSS),has garnered significant interest due to its cost-effective nature.This study investigates the reaction process and growth kinetics involved in MSS,shedding light on key aspects of the process.The involvement of Ti powder through liquid-phase mass transfer is revealed,where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C content gradient on both sides of the carbide.Furthermore,the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer,rather than the chemical reaction rate.To analyze the kinetics,the thickness of the carbide layer is measured with respect to heat treatment time and temperature,unveiling a parabolic relationship within the temperature range of 700-1300℃.The estimated activation energy for the reaction is determined to be 179283 J·mol^(-1).These findings offer valuable insights into the synthesis of carbide coatings via MSS,facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.展开更多
In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are e...In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.展开更多
The release of essential nutrients from soil minerals for plant growth in calcareous soils,facilitated by organic extractants,is critical in semi-arid areas,particularly for elements affected by high soil pH.This stud...The release of essential nutrients from soil minerals for plant growth in calcareous soils,facilitated by organic extractants,is critical in semi-arid areas,particularly for elements affected by high soil pH.This study aims to investigate the release of calcium(Ca),magnesium(Mg),and phosphorus(P)through the application of wood vinegar extract in surface calcareous soils in Borojerd City,Lorestan Province,Iran.The experiment was conducted using a completely randomized design with three replications.The treatments included soils from three different land uses:vineyard,wheat field,and rangeland,each treated with 1.00%wood vinegar solution.Cumulative measurements of the specified elements were recorded over 10 consecutive 0.5 h intervals.The release data were analyzed using four various kinetic models(Elovich equation,parabolic diffusion law,power function equation,and zero-order kinetics).The highest concentrations recorded were for Ca(39,500.00 mg/kg),Mg(5880.00 mg/kg),and P(5.00 mg/kg)in grape cultivation.The findings revealed a significant difference in Ca release between grape cultivation and rangeland(P<0.01),while the Mg release showed a significant difference between both grape cultivation and rangeland and wheat cultivation(P<0.01).Additionally,the cumulative release of P showed significant differences between grape cultivation and both wheat and rangeland(P<0.01).The results indicated that the zero-order kinetics provided the best fit for the data(R^(2)=0.99).The maximum initial release amount was observed in grape cultivation when applying the zero-order kinetics,while the highest release rate was achieved using the parabolic diffusion law across three applications.Wood vinegar had the capacity to degrade various clay minerals,including vermiculite,smectite,palygorskite,and,to some extent,illite,resulting in the release of associated elements.Consequently,it can be concluded that wood vinegar can be effectively utilized in grape cultivation as an agent for reducing soil acidity,thereby enhancing the availability of soil nutrients and decreasing reliance on chemical fertilizers.展开更多
In the present study, we studied the inhibitory effects of chelidonine and rutaecarpin on porcine pancreatic a-amylase （PPA） catalyzed hydrolysis using 2-chloro-4-nitrophenyl-4-O-β-D-galactopyranosylmaltoside （Gal...In the present study, we studied the inhibitory effects of chelidonine and rutaecarpin on porcine pancreatic a-amylase （PPA） catalyzed hydrolysis using 2-chloro-4-nitrophenyl-4-O-β-D-galactopyranosylmaltoside （Gal-G2-α-CNP）. We, for the first time, provided kinetic report and detailed inhibitory effects of both compounds on PPA. Lineweaver-Burk plot revealed that the inhibition was a mixed-noncompetitive type, and only one molecule of inhibitor bound to the enzyme or to the enzyme-substrate complex. Kinetic constants calculated from secondary plots were in millimole range. Dissociation constants of enzyme-inhibitor complex （KEI） were 0.9 mM and 3.5 mM, respectively. Moreover, dissociation constants of enzyme-inhibitor-substrate complex （KESI） were 0.04 mM and 0.31 mM, respectively. These data indicated that the inhibition was more inclined to competitive to Gal-G2-α-CNP hydrolysis. Further molecular docking study manifested that hydrogen bonding formed between acarbose and aspartic acid （Asp300）, histidine （His305） and glycine （Gly3-6）, while hydrogen bonding was observed between chelidonine and glutamic acid （Glu233）, lysine （Lys200） and His305. In addition, rutaecarpine had only one hydrogen bond with Lys200. Our data indicated that chelidonine and rutaecarpine were two promising drug candidates, and chelidonine possessed stronger inhibitory effect compared with rutaecarpine.展开更多
Many electrochemical energy storage devices,such as batteries,supercapacitors,and metal ion capacitors,rely on effective and inexpensive electrode materials.Herein,we have developed highly active nitrogen-doped porous...Many electrochemical energy storage devices,such as batteries,supercapacitors,and metal ion capacitors,rely on effective and inexpensive electrode materials.Herein,we have developed highly active nitrogen-doped porous carbon nanofoams(NPCNs-600-N)for sodium-ion capacitors(SICs).NPCNs-600-N have a highly porous framework,extended interlayer spacing(0.41 nm),and lots of surface functional groups.Accordingly,NPCNs-600-N achieves a high reversible capacity(301 mAh·g^(-1)at 0.05 A·g^(-1)),superior rate capability(112 mAh·g^(-1)at 5.00 A·g^(-1)),and ultra-stable cyclability.The excellent rate and cycling performance originate from the abundant active sites and porous architecture of NPCNs-600-N.Further-more,SICs device is constructed by employing the NPCNs-600-N as the battery-like anode and commercial superconductive carbon black as the capacitive cathode,which delivers high energy/power densities of 92 Wh·kg^(-1)/15984 W·kg^(-1)with a remarkable cyclability(93%reten-tion over 5000 cycles at 1.00 A·g^(-1)).The methodology of the work enables the simultaneous tuning of the porous architectures and surface function groups of carbon for high-performance SICs.展开更多
Biodegradation has become a popular alternative remediation technology for its economic and ecological advantages. An aerobic bacterium （strain ZW） capable of degrading α-pinene was isolated from a biofilter by a s...Biodegradation has become a popular alternative remediation technology for its economic and ecological advantages. An aerobic bacterium （strain ZW） capable of degrading α-pinene was isolated from a biofilter by a selective enrichment. Based on the 16S rRNA gene analysis and physiochemical properties, this strain was identified as Pseudomonas veronii. Under the optimized condition achieved by the response surface methodology （RSM）, as well as pH 6.82, temperature 26.3℃ and NaC1 concentration 1.36%, almost 100% α-pinene could be removed within 45 hr. Enzymatic biodegradation by the crude intracellular enzyme could be described well by the Michaelis-Menten model in which the maximum degradation rate Vraax and the half-saturation constant Km were calculated to be 0.431 mmol/（L.min） and 0.169 mmol/L, respectively. Activity assay of catechol suggested that the strain ZW possessed a catechol- 1,2-dioxygenase and could decompose benzene-ring through ortho ring cleavage. Based on the identified intermediates by GC/MS, a new metabolic pathway was proposed, in which the final metabolites were some simpler organic and inorganic compounds. The present work demonstrated that the strain ZW would have a great application prospect for the remediation of α-pinene-contaminated environment.展开更多
In this work,a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking(FCC) riser reactor for SOxtreatment(FCC-DeSOx) is proposed.The process leverages the high temperatu...In this work,a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking(FCC) riser reactor for SOxtreatment(FCC-DeSOx) is proposed.The process leverages the high temperatures and hydrocarbon concentrations in the FCC riser reactor to convert SOxinto H_(2)S.Subsequently,H_(2)S,along with the cracked gas,is processed downstream to produce sulfur.Thermodynamic analysis of the key reduction reactions in the FCC-DeSOxprocess revealed that complete conversion of SOxto H_(2)S is feasible in the dry gas(hydrogen-rich) prelift zone,as well as the upper and lower zones of the riser,upon achieving thermodynamic equilibrium.Experimental studies were conducted to replicate the conditions of these reaction zones using a low concentration of hydrogen gas as the reducing agent.Through process optimization,investigation of the minimum reaction time,and kinetic studies,the potential of this method for the complete reduction of SOxwas further confirmed.展开更多
In order to restrain the huge volume expansion of bismuth(Bi)anodes in sodium ion batteries(SIBs),the core-shell structure Bi@mesoporous carbon nanospheres(Bi@mC)composite was designed and prepared by sol-gel method c...In order to restrain the huge volume expansion of bismuth(Bi)anodes in sodium ion batteries(SIBs),the core-shell structure Bi@mesoporous carbon nanospheres(Bi@mC)composite was designed and prepared by sol-gel method coupled heat treatment.Structural characterization displays that the average diameter of the as-prepared Bi@mC composites is about 200 nm and thickness of the N-doped mesoporous carbon shells is 20-30 nm.Electrochemical test and kinetic analysis results show that the mesoporous carbon shell can not only effectively relieve the stress caused by volume expansion of Bi and protect active material from pulverization caused by the stress during charging/discharging process,but also facilitate quick diffusion of sodium ions,thus improving rate and cycling performance.Bi@mC delivers a high specific capacity of 279 mA·h/g and a capacity retention of 97.6%after 3500 cycles at a current density of 5 A/g.Even at a high current density of 20 A/g,Bi@mC can still maintain a high specific capacity of 266 mA·h/g.Additionally,the Bi@mC//NVP full button sodium-ion batteries(SIBs)assembled using Bi@mC anode and Na_(3)V_(2)(PO_(4))_(3)(NVP)cathode deliver an energy density of 182 W·h/kg.展开更多
Oxidative coupling of methane(OCM)is a catalytic partial oxidation process that directly converts methane into C_(2) products.For this high temperature reaction,understanding the radical behavior through experimental ...Oxidative coupling of methane(OCM)is a catalytic partial oxidation process that directly converts methane into C_(2) products.For this high temperature reaction,understanding the radical behavior through experimental investigation is important in correlating the catalytic activity and the products.In this work,a spatial resolution online mass spectrometry(MS)system was developed and applied to a Mn-Na_(2)WO_(4)/SiO_(2) catalyzed OCM system.In addition to the residue gas analysis,the system obtained the distribution information of the reactants and products in the reactor.At various setting temperatures,all species online MS signals were collected at different positions,mapping the reaction activity covering parameters including temperature,time and space.The distribution behavior of the catalytic activity,selectivity,and apparent activation energy were kinetically analyzed.Selectivity and additional carbon balance analysis strongly supported the radical coupling model of OCM and indicated that after the catalytic bed layer,there is a significant length in the reactor(>2 mm)filled with radicals.Based on the result,a designed new method by tuning the temperature field in the reactor was found effectively to improve the catalytic activity,especially the C_(2) yield from 702 to 773℃.展开更多
A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of...A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of pneumatic valve the displacement is controlled by electronic control valve. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed according to the geometrical and kinematical information of the compressor. Using the model, the effect of relevant parameters on variable displace control is estimated. It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneumatic valves. And by using this new electronic control device, the optimum systemic control of AAC is available.展开更多
The photodegradation of gaseous dichloromethane （DCM） by a vacuum ultraviolet （VUV） light in a spiral reactor was investigated with different reaction media and initial concentrations. Through the combination of d...The photodegradation of gaseous dichloromethane （DCM） by a vacuum ultraviolet （VUV） light in a spiral reactor was investigated with different reaction media and initial concentrations. Through the combination of direct photolysis, O3 oxidation and HO. oxidation, DCM was ultimately mineralized into inorganic compounds （such as HC1, CO2, H20, etc.） in the air with relative humidity （RH） of 75%-85%. During the photodegradation process, some small organic acids （including formic acid, acetic acid） were also detected and the intermediates were more soluble than DCM, providing a possibility for its combination with subsequent biodegradation. Based on the detected intermediates and the confirmed radicals, a photodegradation pathway of DCM by VUV was proposed. With RH 75%- 80% air as the reaction medium, the DCM removal followed the second-order kinetic model at inlet concentration of 100-1000 mg/m3. Kinetic analysis showed that the reaction media affected the kinetic constants of DCM conversion by a large extent, and RH 80% air could cause a much lower half-life for its conversion. Such results supported the possibility that VUV photodegradation could be used not only for the mineralization of DCM but also as a pretreatment before biodegradation.展开更多
The influence of different pre-oxidation temperatures and pre-oxidation degrees on the reduction and fluidization behaviors of magnetite-based iron ore was investigated in a hydrogen-induced fluidized bed.The raw magn...The influence of different pre-oxidation temperatures and pre-oxidation degrees on the reduction and fluidization behaviors of magnetite-based iron ore was investigated in a hydrogen-induced fluidized bed.The raw magnetite-based iron ore was pre-oxidized at 800 and1000℃ for a certain time to reach a partly oxidation and deeply oxidation state.The structure and morphology of the reduced particles were analyzed via optical microscope and scanning electron microscopy(SEM).The reaction kinetic mechanism was determined based on the double-logarithm analysis.The results indicate that the materials with higher oxidation temperature and wider particle size range show better fluidization behaviors.The lower oxidation temperature is more beneficial for the reduction rate,especially in the later reduction stage.The pre-oxidation degree shows no obvious influence on the fluidization and reduction behaviors.Based on the kinetic analysis,the reduction progress can be divided into three stages.The reduction mechanism was discussed combing the surface morphology and phase structure.展开更多
基金Project(2013CB632605)supported by the National Basic Research Development Program of ChinaProjects(51274178,51274179)supported by the National Natural Science Foundation of China
文摘A novel process was developed for the decomposition of vanadium slag using KOH sub-molten salt under ambient pressure, and the effects of reaction temperature, alkali-to-ore mass ratios, particle size, and stirring speed on vanadium and chromium extraction were studied. The results suggest that the reaction temperature and KOH-to-ore mass ratio are more influential factors for the extraction of vanadium and chromium. Under the optimal reaction conditions （temperature 180 °C, initial KOH-to-ore mass ratio 4：1, stirring speed 700 r/min, gas flow 1 L/min, and reaction time 300 min）, vanadium and chromium extraction rates can reach up to 95% and 90%, respectively. Kinetics analysis results show that the decomposing process of vanadium slag in KOH sub-molten salt can be well interpreted by the shrinking core model under internal diffusion control. The apparent activation energies for vanadium and chromium are 40.54 and 50.27 kJ/mol, respectively.
基金The Project was supported by the National Natural Science Foundation of China
文摘The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reaction of La^(3+),Gd^(3+)and Ho^(3+)with TBA were studied.It is shown in the study that prerequisites for performing differential rate analysis for binary rare earths with TBA are that the pseudo-first-order parallel reaction mechanism should be conformed with,no multinuclear complex would be formed and the co-coloration effects could be neglected.
文摘The kinetic behaviours of the substitution reaction of rare earth-PHA with CyDTA were studied systemati- cally.The relationship between the rate constant and atomic number was discussed.The rate differentiation val- ue R_d(R_d=lgk_(z+n)-lgk_z)was proposed to evaluate the possibility of differential kinetic analysis.The R_d value between the neighbouring lanthanide ions first increases and then decreases along with increasing atomic number, so that the middle and heavy rare earth mixture(such as Sm-Gd and Gd-Y)are ideal systems for the differential rate kinetic analysis.
文摘The effects of long-term moisture changes on the migration,release,and bioavailability of selenium in soil are complex.Due to the lack of effective monitoring methods for precise quantification,its dynamic behavior is still unclear.Based on the DGT(Diffusive Gradients in Thin-films)technology,this study sets up three moisture control scenarios:continuous wet,wet-dry alternating,and continuous dry,and carries out a 6-month soil moisture control experiment.In the experiment,the DGT device collected the diffusion gradient data of soil selenium under different scenarios,and analyzed the migration characteristics of selenium in combination with the adsorption isotherm.Meanwhile,the release rate,migration coefficient,and bioavailability parameters of selenium are calculated by fitting the first-order kinetic model,further verifying the reliability and applicability of the DGT data.The experimental results demonstrate that under continuous wet conditions,the release rate of soil selenium reaches 1.85µg·cm^(-2)·h^(-1),with a migration coefficient of 0.012 cm^(2)·h^(-1)and a bioavailability parameter of 0.74;under wet-dry alternating conditions,they are 1.42µg·cm^(-2)·h^(-1),0.01 cm^(2)·h^(-1),and 0.68,respectively;under continuous dry conditions,the release rate of soil selenium is the smallest,at 0.88µg·cm^(-2)·h^(-1),with a migration coefficient of 0.004 cm^(-2)·h^(-1)and a bioavailability parameter of 0.5.The results of this experiment reveal the dynamic behavior of soil selenium under different moisture conditions and reflect the high efficiency of DGT technology in dynamic monitoring and quantitative analysis of soil selenium behavior,providing a scientific basis for the optimal management of rhizosphere soil selenium.
基金supported by the Natural Science Foundation of Shanxi Province(Grant No.202203021221120)The Open Fund of MCRI-Shannxi Laboratory of Energetic Materials(Grant No.204-J-2024-2622)。
文摘This study prepared a class of RDX-based composite microspheres(RAF)containing ADN and FKM2602.The reaction kinetics of RAF composite microspheres were effectively improved by maintaining the system's high energy and safety performance.In the close packing state,when the heating rate is rapid,the thermal stability of RAF composite microspheres is better than that of RDX;the close packing state will reduce the degree of freedom of RDX and ADN reaction but will increase the degree of freedom of RAF composite microsphere reaction.The thermal conductivity of RAF composite microspheres is close to that of RDX.In the ignition experiment,the flame of RAF composite microspheres can be maintained without the external heat source.Regarding safety,the H50of RAF composite microspheres was 274.04%higher than that of RDX.The detonation velocity of RAF composite microspheres is slightly higher than that of raw material RDX.Overall,these findings highlight the effectiveness of ADN in enhancing the reaction kinetics of RDX-based composites.
文摘The purity of the brazing alloys applied is necessary to be improved with the increasing cleanness of steel. Calcium is easily brought into the widely ased brazing alloy, Ag-Cu-Zn, during the producing process. This paper aims at revealing the effect of calcium on the melting behavior of the brazing alloy. The thermal analysis kinetics of silver alloy with trace calcium was studied by using differential scanning calorimetry （ DSC ） , and the enthalpy peaks were analyzed by differential methods. The rate constant of phase transformation in the probable brazing temperature range goes up with increasing calcium content, according to the values of the apparent activation energy, E, and the frequeney constant, A. It is concluded that the calcium addition could improve the melting performance of Ag-Cu-Zn brazing alloy.
基金supported by the Natural Science Foundation of China under Grant(No.52172099)the Provincial Joint Fund of Shaanxi(2021JLM-28).
文摘The large accumulation of coal gangue,a common industrial solid waste,causes severe environmental problems,and green development strategies are required to transform this waste into high-value-added products.In this study,low-cost ceramsites adsorbents were prepared from waste gangue,silt coal,and peanut shells and applied to remove the organic dye methylene blue from wastewater.We investigated the microstructure of ceramsites and the effects of the sintering atmosphere,sintering temperature,and solution pH on their adsorption performance.The ceramsites sintered at 800℃under a nitrogen atmosphere exhibited the largest three-dimensional-interconnected hierarchical porous structure among the prepared ceramsites;further,it exhibited the highest methylene blue adsorption performance,with an adsorption capacity of 0.954 mg·g^(−1),adsorption efficiency of over 95%,and adsorption equilibrium time of 1 h at a solution pH of 9.The removal efficiency remained greater than 75%after five adsorption cycles.The adsorption kinetics data were analyzed using various models,including the pseudosecond-order kinetic model and Langmuir equation,and the adsorption was attributed to electrostatic interactions between the dyes and ceramsites,n-interactions,and hydrogen bonds.The prepared coal gangue ceramsites exhibited excellent adsorption capacities,removal rates,and cyclic stabilities,demonstrating their promising application prospects for the comprehensive utilization of solid waste and for wastewater treatment.
基金supported by the National Natural Science Foundation of China [Grant No. 22278452]the SINOPEC Research Institute of Safety Engineering for financially supporting this project。
文摘In the conversion of methane and propane under high temperature and pressure,the ignition delay time(IDT)is a key parameter to consider for designing an inherently safe process.In this study,the IDT characteristics of methane and propane(700–1000 K,10–20 bar)were studied experimentally and using kinetic modeling tools at stoichiometric fuel-tooxygen ratios.All the experiments were conducted through insentropic compression.The reliable experimental data were obtained by using the adiabatic core hypothesis,which can be used to generate and validate the detailed chemical kinetics model.The IDTs of methane and propane were recorded by a rapid compression machine(RCM)and compared to the predicted values obtained by the NUIGMech 3.0 mechanism.To test the applicability of NUIGMech 3.0 under different reaction conditions,the influence of temperature in the range of 700–1000 K(and the influence of pressure in the range of 10–20 bar)on the IDT was studied.The results showed that NUIGMech 3.0 could reasonably reproduce the experimentally determined IDT under the wide range of conditions studied.The constant volume chemical kinetics model was used to reveal the effect of temperature on the elementary reaction,and the negative temperature coefficient(NTC)behavior of propane was also observed at 20 bar.The experimental data can serve as a reference for the correction and application of kinetic data,as well as provide a theoretical basis for the safe conversion of low-carbon hydrocarbon chemicals.
基金This work was financially supported by the National Natural Science Foundation of China(No.52171144)the Fundamental Research Special Zone Program of Shanghai Jiao Tong University(No.21TQ1400215).
文摘The synthesis of carbide coatings on graphite substrates using molten salt synthesis(MSS),has garnered significant interest due to its cost-effective nature.This study investigates the reaction process and growth kinetics involved in MSS,shedding light on key aspects of the process.The involvement of Ti powder through liquid-phase mass transfer is revealed,where the diffusion distance and quantity of Ti powder play a crucial role in determining the reaction rate by influencing the C content gradient on both sides of the carbide.Furthermore,the growth kinetics of the carbide coating are predominantly governed by the diffusion behavior of C within the carbide layer,rather than the chemical reaction rate.To analyze the kinetics,the thickness of the carbide layer is measured with respect to heat treatment time and temperature,unveiling a parabolic relationship within the temperature range of 700-1300℃.The estimated activation energy for the reaction is determined to be 179283 J·mol^(-1).These findings offer valuable insights into the synthesis of carbide coatings via MSS,facilitating their optimization and enhancing our understanding of their growth mechanisms and properties for various applications.
基金Ho Chi Minh City University of Technology(HCMUT)Vietnam National University Ho Chi Minh City(VNU-HCM)for supporting this study。
文摘In this paper,two lifting mechanism models with opposing placements,which use the same hydraulic hoist model and have the same angle of 50°,have been developed.The mechanical and hydraulic simulation models are established using MATLAB Simscape to analyze their kinetics and dynamics in the lifting and holding stages.The simulation findings are compared to the analytical calculation results in the steady state,and both methods show good agreement.In the early lifting stage,Model 1 produces greater force and discharges goods in the container faster than Model 2.Meanwhile,Model 2 reaches a higher force and ejects goods from the container cleaner than its counterpart at the end lifting stage.The established simulation models can consider the effects of dynamic loads due to inertial moments and forces generated during the system operation.It is crucial in studying,designing,and optimizing the structure of hydraulic-mechanical systems.
文摘The release of essential nutrients from soil minerals for plant growth in calcareous soils,facilitated by organic extractants,is critical in semi-arid areas,particularly for elements affected by high soil pH.This study aims to investigate the release of calcium(Ca),magnesium(Mg),and phosphorus(P)through the application of wood vinegar extract in surface calcareous soils in Borojerd City,Lorestan Province,Iran.The experiment was conducted using a completely randomized design with three replications.The treatments included soils from three different land uses:vineyard,wheat field,and rangeland,each treated with 1.00%wood vinegar solution.Cumulative measurements of the specified elements were recorded over 10 consecutive 0.5 h intervals.The release data were analyzed using four various kinetic models(Elovich equation,parabolic diffusion law,power function equation,and zero-order kinetics).The highest concentrations recorded were for Ca(39,500.00 mg/kg),Mg(5880.00 mg/kg),and P(5.00 mg/kg)in grape cultivation.The findings revealed a significant difference in Ca release between grape cultivation and rangeland(P<0.01),while the Mg release showed a significant difference between both grape cultivation and rangeland and wheat cultivation(P<0.01).Additionally,the cumulative release of P showed significant differences between grape cultivation and both wheat and rangeland(P<0.01).The results indicated that the zero-order kinetics provided the best fit for the data(R^(2)=0.99).The maximum initial release amount was observed in grape cultivation when applying the zero-order kinetics,while the highest release rate was achieved using the parabolic diffusion law across three applications.Wood vinegar had the capacity to degrade various clay minerals,including vermiculite,smectite,palygorskite,and,to some extent,illite,resulting in the release of associated elements.Consequently,it can be concluded that wood vinegar can be effectively utilized in grape cultivation as an agent for reducing soil acidity,thereby enhancing the availability of soil nutrients and decreasing reliance on chemical fertilizers.
基金State Key Laboratory of Natural and Biomimetic Drugs 2013 Funded Project "Establishment and Application an Online Natural Medicines System with Efficient Separation,Structural Identification and Activity Detection"
文摘In the present study, we studied the inhibitory effects of chelidonine and rutaecarpin on porcine pancreatic a-amylase （PPA） catalyzed hydrolysis using 2-chloro-4-nitrophenyl-4-O-β-D-galactopyranosylmaltoside （Gal-G2-α-CNP）. We, for the first time, provided kinetic report and detailed inhibitory effects of both compounds on PPA. Lineweaver-Burk plot revealed that the inhibition was a mixed-noncompetitive type, and only one molecule of inhibitor bound to the enzyme or to the enzyme-substrate complex. Kinetic constants calculated from secondary plots were in millimole range. Dissociation constants of enzyme-inhibitor complex （KEI） were 0.9 mM and 3.5 mM, respectively. Moreover, dissociation constants of enzyme-inhibitor-substrate complex （KESI） were 0.04 mM and 0.31 mM, respectively. These data indicated that the inhibition was more inclined to competitive to Gal-G2-α-CNP hydrolysis. Further molecular docking study manifested that hydrogen bonding formed between acarbose and aspartic acid （Asp300）, histidine （His305） and glycine （Gly3-6）, while hydrogen bonding was observed between chelidonine and glutamic acid （Glu233）, lysine （Lys200） and His305. In addition, rutaecarpine had only one hydrogen bond with Lys200. Our data indicated that chelidonine and rutaecarpine were two promising drug candidates, and chelidonine possessed stronger inhibitory effect compared with rutaecarpine.
基金financially supported by the Natural Science Foundation of Jiangsu Province (No. BK20170549)the National Natural Science Foundation of China (Nos. 21706103 and 22075109)+2 种基金Nanjing Tech University Research Start-Up Fund (No. 38274017111)Zhongyan Jilantai Chlor-Alkali Chemical Co., Ltd (No. FZ2019-RWS-027)the Open Fund of the Key Laboratory of Fine Chemical Application Technology of Luzhou (No. HYJH-2101-B)
文摘Many electrochemical energy storage devices,such as batteries,supercapacitors,and metal ion capacitors,rely on effective and inexpensive electrode materials.Herein,we have developed highly active nitrogen-doped porous carbon nanofoams(NPCNs-600-N)for sodium-ion capacitors(SICs).NPCNs-600-N have a highly porous framework,extended interlayer spacing(0.41 nm),and lots of surface functional groups.Accordingly,NPCNs-600-N achieves a high reversible capacity(301 mAh·g^(-1)at 0.05 A·g^(-1)),superior rate capability(112 mAh·g^(-1)at 5.00 A·g^(-1)),and ultra-stable cyclability.The excellent rate and cycling performance originate from the abundant active sites and porous architecture of NPCNs-600-N.Further-more,SICs device is constructed by employing the NPCNs-600-N as the battery-like anode and commercial superconductive carbon black as the capacitive cathode,which delivers high energy/power densities of 92 Wh·kg^(-1)/15984 W·kg^(-1)with a remarkable cyclability(93%reten-tion over 5000 cycles at 1.00 A·g^(-1)).The methodology of the work enables the simultaneous tuning of the porous architectures and surface function groups of carbon for high-performance SICs.
基金supported by the National Natural Science Foundation of China (No. 51178431)the International S&T Cooperation Program of China (No.2011DFA92660)+1 种基金the Key Project of Science and Technology Department of Zhejiang Province (No. 2011C13023)Zhejiang Provincial Funds for Distinguished Young Scientists (No. R5090230)
文摘Biodegradation has become a popular alternative remediation technology for its economic and ecological advantages. An aerobic bacterium （strain ZW） capable of degrading α-pinene was isolated from a biofilter by a selective enrichment. Based on the 16S rRNA gene analysis and physiochemical properties, this strain was identified as Pseudomonas veronii. Under the optimized condition achieved by the response surface methodology （RSM）, as well as pH 6.82, temperature 26.3℃ and NaC1 concentration 1.36%, almost 100% α-pinene could be removed within 45 hr. Enzymatic biodegradation by the crude intracellular enzyme could be described well by the Michaelis-Menten model in which the maximum degradation rate Vraax and the half-saturation constant Km were calculated to be 0.431 mmol/（L.min） and 0.169 mmol/L, respectively. Activity assay of catechol suggested that the strain ZW possessed a catechol- 1,2-dioxygenase and could decompose benzene-ring through ortho ring cleavage. Based on the identified intermediates by GC/MS, a new metabolic pathway was proposed, in which the final metabolites were some simpler organic and inorganic compounds. The present work demonstrated that the strain ZW would have a great application prospect for the remediation of α-pinene-contaminated environment.
基金supported by General Program of National Natural Science Foundation of China (22178385)。
文摘In this work,a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking(FCC) riser reactor for SOxtreatment(FCC-DeSOx) is proposed.The process leverages the high temperatures and hydrocarbon concentrations in the FCC riser reactor to convert SOxinto H_(2)S.Subsequently,H_(2)S,along with the cracked gas,is processed downstream to produce sulfur.Thermodynamic analysis of the key reduction reactions in the FCC-DeSOxprocess revealed that complete conversion of SOxto H_(2)S is feasible in the dry gas(hydrogen-rich) prelift zone,as well as the upper and lower zones of the riser,upon achieving thermodynamic equilibrium.Experimental studies were conducted to replicate the conditions of these reaction zones using a low concentration of hydrogen gas as the reducing agent.Through process optimization,investigation of the minimum reaction time,and kinetic studies,the potential of this method for the complete reduction of SOxwas further confirmed.
基金the support from National Natural Science Foundation of China (No.52004179)the Fundamental Research Program of Shanxi Province,China (Nos.202403021211028,202303021211036)+1 种基金Shanxi Water and Wood New Carbon Materials Technology Co.,Ltd.,ChinaGuangdong One Nano Technology Co.,Ltd.,China。
文摘In order to restrain the huge volume expansion of bismuth(Bi)anodes in sodium ion batteries(SIBs),the core-shell structure Bi@mesoporous carbon nanospheres(Bi@mC)composite was designed and prepared by sol-gel method coupled heat treatment.Structural characterization displays that the average diameter of the as-prepared Bi@mC composites is about 200 nm and thickness of the N-doped mesoporous carbon shells is 20-30 nm.Electrochemical test and kinetic analysis results show that the mesoporous carbon shell can not only effectively relieve the stress caused by volume expansion of Bi and protect active material from pulverization caused by the stress during charging/discharging process,but also facilitate quick diffusion of sodium ions,thus improving rate and cycling performance.Bi@mC delivers a high specific capacity of 279 mA·h/g and a capacity retention of 97.6%after 3500 cycles at a current density of 5 A/g.Even at a high current density of 20 A/g,Bi@mC can still maintain a high specific capacity of 266 mA·h/g.Additionally,the Bi@mC//NVP full button sodium-ion batteries(SIBs)assembled using Bi@mC anode and Na_(3)V_(2)(PO_(4))_(3)(NVP)cathode deliver an energy density of 182 W·h/kg.
文摘Oxidative coupling of methane(OCM)is a catalytic partial oxidation process that directly converts methane into C_(2) products.For this high temperature reaction,understanding the radical behavior through experimental investigation is important in correlating the catalytic activity and the products.In this work,a spatial resolution online mass spectrometry(MS)system was developed and applied to a Mn-Na_(2)WO_(4)/SiO_(2) catalyzed OCM system.In addition to the residue gas analysis,the system obtained the distribution information of the reactants and products in the reactor.At various setting temperatures,all species online MS signals were collected at different positions,mapping the reaction activity covering parameters including temperature,time and space.The distribution behavior of the catalytic activity,selectivity,and apparent activation energy were kinetically analyzed.Selectivity and additional carbon balance analysis strongly supported the radical coupling model of OCM and indicated that after the catalytic bed layer,there is a significant length in the reactor(>2 mm)filled with radicals.Based on the result,a designed new method by tuning the temperature field in the reactor was found effectively to improve the catalytic activity,especially the C_(2) yield from 702 to 773℃.
文摘A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of pneumatic valve the displacement is controlled by electronic control valve. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed according to the geometrical and kinematical information of the compressor. Using the model, the effect of relevant parameters on variable displace control is estimated. It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneumatic valves. And by using this new electronic control device, the optimum systemic control of AAC is available.
基金supported by the National Natural Science Foundation of China (No. 20976165,21207115)the Ph.D.Programs Foundation of Ministry of Education of China(No. 20093317110003)the Zhejiang Provincial Funds for Distinguished Young Scientists (No. R5090230)
文摘The photodegradation of gaseous dichloromethane （DCM） by a vacuum ultraviolet （VUV） light in a spiral reactor was investigated with different reaction media and initial concentrations. Through the combination of direct photolysis, O3 oxidation and HO. oxidation, DCM was ultimately mineralized into inorganic compounds （such as HC1, CO2, H20, etc.） in the air with relative humidity （RH） of 75%-85%. During the photodegradation process, some small organic acids （including formic acid, acetic acid） were also detected and the intermediates were more soluble than DCM, providing a possibility for its combination with subsequent biodegradation. Based on the detected intermediates and the confirmed radicals, a photodegradation pathway of DCM by VUV was proposed. With RH 75%- 80% air as the reaction medium, the DCM removal followed the second-order kinetic model at inlet concentration of 100-1000 mg/m3. Kinetic analysis showed that the reaction media affected the kinetic constants of DCM conversion by a large extent, and RH 80% air could cause a much lower half-life for its conversion. Such results supported the possibility that VUV photodegradation could be used not only for the mineralization of DCM but also as a pretreatment before biodegradation.
基金the funding support of K1-MET GmbH,metallurgical competence centerthe financial support from the program of China Scholarship Council(No.201908420284)。
文摘The influence of different pre-oxidation temperatures and pre-oxidation degrees on the reduction and fluidization behaviors of magnetite-based iron ore was investigated in a hydrogen-induced fluidized bed.The raw magnetite-based iron ore was pre-oxidized at 800 and1000℃ for a certain time to reach a partly oxidation and deeply oxidation state.The structure and morphology of the reduced particles were analyzed via optical microscope and scanning electron microscopy(SEM).The reaction kinetic mechanism was determined based on the double-logarithm analysis.The results indicate that the materials with higher oxidation temperature and wider particle size range show better fluidization behaviors.The lower oxidation temperature is more beneficial for the reduction rate,especially in the later reduction stage.The pre-oxidation degree shows no obvious influence on the fluidization and reduction behaviors.Based on the kinetic analysis,the reduction progress can be divided into three stages.The reduction mechanism was discussed combing the surface morphology and phase structure.
