kinetics

摘要： MgH_(2)with a large hydrogen capacity is regarded as a promising hydrogen storage material.However,it still suffers from high thermal stability and sluggish kinetics.In this paper,highly dispersed nano-Ni has been successfully prepared by using the polyol reduction method with an average size of 2.14 nm,which significantly improves the de/rehydrogenation properties of MgH_(2).The MgH_(2)–10wt%nano-Ni sample starts releasing H_(2)at 497 K,and roughly 6.2wt%H_(2)has been liberated at 583 K.The rehydrogenation kinetics of the sample are also greatly improved,and the adsorption capacity reaches 5.3wt%H_(2)in 1000 s at 482 K and under 3 MPa hydrogen pressure.Moreover,the activation energies of de/rehydrogenation of the MgH_(2)–10wt%nano-Ni sample are reduced to(88±2)and(87±1)kJ·mol−1,respectively.In addition,the thermal stability of the MgH_(2)–10wt%nano-Ni system is reduced by 5.5 kJ per mol H_(2)from that of pristine MgH_(2).This finding indicates that nano-Ni significantly improves both the thermodynamic and kinetic performances of the de/rehydrogenation of MgH_(2),serving as a bi-functional additive of both reagent and catalyst.

摘要： Combustion performance of pulverized coal(PC)in blast furnace(BF)process is regarded as a criteria parameter to assess the prop-er injection dosage of PC.In this paper,effects of two kinds of additives,Fe_(2)O_(3) and CaO,on PC combustion were studied using the thermo-gravimetric method.The results demonstrate that both the Fe_(2)O_(3) and CaO can promote combustion performance index of PC including igni-tion index(C_(i)),burnout index(D_(b)),as well as comprehensive combustibility index(S_(n)).The S_(n) increases from 1.37×10^(−6) to 2.16×10^(−6)%2·min^(−2)·°C^(−3) as the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%.Additionally,the combustion kinetics of PC was clarified using the Coats-Redfern method.The results show that the activation energy(E)of PC combustion decreases after adding the above additives.For instance,the E decreases from 56.54 to 35.75 kJ/mol when the Fe_(2)O_(3) proportion increases from 0 to 5.0wt%,which supports the improved combustion per-formance.Moreover,it is uneconomic to utilize pure Fe_(2)O_(3) and CaO in production.Based on economy analysis,we selected the iron-bearing dust(IBD)which contains much Fe_(2)O_(3) and CaO component to investigate,and got the same effects.Therefore,the IBD is a potential option for catalytic PC combustion in BF process.

摘要： Recovering the iron(Fe)and phosphorus(P)contained in steelmaking slags not only reduces the environmental burden caused by the accumulated slag,but also is the way to develop a circular economy and achieve sustainable development in the steel industry.We had pre-viously found the possibility of recovering Fe and P resources,i.e.,magnetite(Fe_(3)O_(4))and calcium phosphate(Ca_(10)P_(6)O_(25)),contained in steel-making slags by adjusting oxygen partial pressure and adding modifier B_(2)O_(3).As a fundamental study for efficiently recovering Fe and P from steelmaking slag,in this study,the crystallization behavior of the CaO-SiO_(2)-FeO-P_(2)O_(5)-B_(2)O_(3) melt has been observed in situ,using a confocal scanning laser microscope(CLSM).The kinetics of nucleation and growth of Fe-and P-rich phases have been calculated using a classical crys-tallization kinetic theory.During cooling,a Fe_(3)O_(4) phase with faceted morphology was observed as the 1st precipitated phase in the isothermal interval of 1300-1150°C,while Ca_(10)P_(6)O_(25),with rod-shaped morphology,was found to be the 2nd phase to precipitate in the interval of 1150-1000°C.The crystallization abilities of Fe_(3)O_(4) and Ca_(10)P_(6)O_(25) phases in the CaO-SiO_(2)-FeO-P_(2)O_(5)-B_(2)O_(3) melt were quantified with the in-dex of(T_(U)−T_(I))/T_(I)(where T_(I) represents the peak temperature of the nucleation rate and TU stands for that of growth rate),and the crystalliza-tion ability of Fe_(3)O_(4) was found to be larger than that of Ca_(10)P_(6)O_(25) phase.The range of crystallization temperature for Fe_(3)O_(4) and Ca_(10)P_(6)O_(25) phases was optimized subsequently.The Fe_(3)O_(4) and Ca_(10)P_(6)O_(25) phases are the potential sources for ferrous feedstock and phosphate fertilizer,respectively.

摘要： Monoclinic Li_(2)V_(2)(PO_(4))_(3);is a promising cathode material with complex charge–discharge behavior.Previous structural investigation of this compound mainly focuses on local environments;while the reaction kinetics and the driving force of irreversibility of this material remain unclear.To fully understand the above issues,both the equilibrium and the non-equilibrium reaction routes have been systematically investigated in this study.Multiple characterization techniques including X-ray diffraction,variable temperature(spinning rate)and ex/in situ ^(7)Li,^(31)P solid state NMR have been employed to provide comprehensive insights into kinetics,dynamics,framework structure evolution and charge ordering,which is essential to better design and application of lithium transition metal phosphate cathodes.Our results suggest that the kinetics process between the non-equilibrium and the quasi-equilibrium delithiation pathways from Li_(2)V_(2)(PO_(4))_(3);to V_(2)(PO_(4))_(3);is related with a slow relaxation from two-site to one-site delithiation.More importantly,it has been demonstrated that the irreversibility in this system is not solely affected by cation and/or charge ordering/disordering,but mainly driven by framework structure distortion.

摘要： Mesophilic biogas production and substrate decomposition is one of the significant limiting steps in biogas generation. The rate of generation and quality often affect the viability of biogas systems. This study assessed the potential for biogas process catalysis using powdered Sorghum bicolor L., Zea mays, and Pennisetum glaucum. The kinetics and biogas generation processes were studied. Experiments were conducted in 1 m3 tubular batch reactors, where batches were dosed with various organic biomolecules. Results show that the use of P. glaucum L. and S. bicolor L. reduced the biogas retention times significantly. Biogas generation commenced after the first day for digesters fed with S. bicolor L. and P. glaucum L. while one with Z. mays and control occurred on day two. The rate of biomethanation and methane content were enhanced. S. bicolor L. led to the highest methane content. Findings reveal that locally available organic biomolecules improved biogas quality and quantity.

摘要： Purpose:This study aimed to compare biomechanical aspects of a novel"running"diagonal stride(DSRUN)with"conventional"diagonal stride(DSCONV)skiing techniques performed at high speed.Methods:Ten elite Italian male junior cross-country skiers skied on a treadmill at 10 km/h and at a 10°incline utilizing both variants of the diagonal stride technique.The 3-dimensional kinematics of the body,poles,and roller skis;the force exerted through the poles and foot plantar surfaces;and the angular motion of the leg joints were determined.Results:Compared to DSCONV,DSRUN demonstrated shorter cycle times(1.05±0.05 s vs.0.75±0.03 s(mean±SD),p<0.001)due to a shorter rolling phase(0.40±0.04 s vs.0.09±0.04 s,p<0.001);greater force applied perpendicularly to the roller skis when they had stopped rolling forward(413±190 N vs.890±170 N,p<0.001),with peak force being attained earlier;prolonged knee extension,with a greater range of motion during the roller ski-stop phase(28°±40 vs.16°±3°,p=0.00014);and more pronounced hip and knee flexion during most of the forward leg swing.The mechanical work performed against friction during rolling was significantly less with DSRUN than with DSCONV(0.04±0.01 J/m/kg vs.0.10±0.02 J/m/kg,p<0.001).Conclusion:Our findings demonstrate that DSRUN is characterize by more rapid propulsion,earlier leg extension,and a greater range of motion of knee joint extension than DSCONV-Further investigations,preferably on snow,should reveal whether DSRUN results in higher acceleration and/or higher peak speed.

摘要： Located at the National University in Bogotá,Colombia,this paper presents the development of the integration of kinematics,simplified kinetic and zero-dimensional models of indicator diagram of a double-acting,single-cylinder steam engine;the model integration is done for two configurations of the distribution system to simulate the instantaneous torque and the average.Two simulations are carried out at different steam entry conditions and an advance angle of 0°for the distribution system,fed with the data obtained from the characterization and metrological survey of the VE(vapor engine)parts in a CAD(computer-aided design)system.It is verified that integrating the models constitutes a simulation tool that allows for the instantaneous torque deliveries and average torque of the accurate operation’s VE.

摘要： Inhibition of protein misfolding and aggregation is a great challenge in the field of biochemical and biopharmaceutical engineering.Alzheimer’s disease(AD)is a protein-misfolding disease,and the interactions between 40-amino-acid-residueβ-amyloid peptide(Aβ_(40)) and its N-terminal truncated peptide Aβ_(11-40) demonstrate that Aβ_(11-40) may play an important role in the pathological process of AD.However,the effect of inhibitors on Aβ_(11-40) aggregation and on the cross-amyloid aggregation(coassembly)between Aβ_(40) and Aβ_(11-40) has never been studied.Herein,coaggregation and seeding interactions between Aβ_(40) and Aβ_(11-40) as well as the effect of epigallocatechin gallate(EGCG),a small molecule inhibitor,on the cross-amyloid aggregation have been investigated by extensive analyses.It is found that Aβ_(11-40) participates in the aggregation of Aβ_(40) and leads to the formation of coaggregates that contain lessβ-sheet structures than pure Aβ_(40) aggregates.The aggregation kinetics along with morphologies and secondary structures of the coaggregates are also significantly affected by the Aβ_(40)/Aβ_(11-40) ratio.EGCG accelerates the nucleation of Aβ_(40) but retards that of Aβ_(11-40) by affecting their elongation and secondary nucleation processes in solution and on solid surfaces.Meanwhile,EGCG makes the conformations of the seeding-induced Aβaggregates more compact,especially for the homologous seedings.Isothermal titration calorimetry measurement indicates that hydrophobic interactions mainly contribute to the inhibition of the two Aβisoforms by EGCG.The findings of this research have provided new insights into Aβaggregation and the effect of an important inhibitor and the results would benefit in the development of potent inhibitors against co-assembly of different amyloid proteins.

摘要： There has been a strong interest in technologies suited for mining and processing of low-grade ores because of the rapid depletion of mineral resources in the world.In most cases,the extraction of copper from such raw materials is achieved by applying the leaching procedures.However,its low extraction efficiency and the long extraction period limit its large-scale commercial applications in copper recovery,even though bioleaching has been widely employed commercially for heap and dump bioleaching of secondary copper sulfide ores.Overcoming the technical challenges requires a better understanding of leaching kinetics and on-site microbial activities.Herein,this paper reviews the current status of main commercial biomining operations around the world,identifies factors that affect chalcocite dissolution both in chemical leaching and bioleaching,summarizes the related kinetic research,and concludes with a discussion of two on-site chalcocite heap leaching practices.Further,the challenges and innovations for the future development of chalcocite hydrometallurgy are presented in the end.

摘要： In this study,three kinds of amide functional group modified hyper-cross-linked adsorption resin were synthesized by alternating radical copolymerization in simple one-step and applied for 5-hydroxymethylfurfural(5-HMF)adsorption.The successful synthesis and properties of adsorbents were evaluated with Fourier transform infrared spectroscopy,scanning electron microscopy,nitrogen adsorption-desorption isotherms,thermogravimetric analysis,and elemental analysis.Poly(N,N’-4,4’-diphenyl methane-bismaleimide-alt-divinylbenzene)(poly(BDM-alt-DVB))resin exhibited highest adsorption capacity for 5-HMF(64.0 mg·g^(-1)wet resin)and excellent adsorption selectivity(a_(5-HMF/LA)=2.71±0.12,α_(5-HMF/FA)=13.88±0.15,α_(5-HMF/Glucose)=11.91±1.11)in the multi-component solution at 25°C.Langmuir isotherm model well fitted the equilibrium adsorption data within the initial 5-HMF concentration range of 0.5-10.0 g·L^(-1) with highest correlation coefficient.Furthermore,the thermodynamic parameters demonstrated that the adsorption of 5-HMF onto poly(BDM-alt-DVB)resin was spontaneous and exothermic.Kinetic study revealed that the adsorption process was fast,reaching equilibrium within12 min.Importantly,the poly(BDM-alt-DVB)resin also demonstrated excellent reusability.In summary,the poly(BDM-alt-DVB)resin will be useful in 5-HMF hydrolysate separation applications.

摘要： Non-isothermal Pyrolysis kinetics phenol-formaldehyde（PF) resin is investigated using thermogravimetry（TG). The TG experiments at controlled heating rates were used for obtaining the kinetic parameters of the reactive system. The research indicates that the pyrolysis process consists of four consecutive distinct stages. The anterior two stages are named as one-dimensional diffusion and three-dimensional reaction regions，while the third stage is characterized as a random nucleation and its subsequent growth，and the latest one can be defined as a chemical reaction region. According to the calculation results of the apparent activation energy Ea，the changes of entropy △S≠，enthalpy △H≠and Gibbs free energy △G≠，the anterior three stages are non-spontaneous processes. While the fourth stage proceeds spontaneously.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.

摘要： To investigate the iron oxidization function in CaO-FeOx-SiO2 slag, gas was injecting into molten so as to oxidize it. The variation of the iron valence states with the oxidizing time in different temperature was obtained by chemical analysis method. Microstructure of slag was observed by metallographic microscope and SEM, and phases composition ascertained by EDX and XRD. The regularity of the phases transformation and the oxidizing kinetic equations of the iron were obtained, which provide a theoretical base for compressively utilizing of the slag.