Microdynamics study on reaction of atom H and radical NH (X~3∑)

The dynamics of the H + NH→N + H2 reaction has been investigated by means of the 3-atom model quasiclassical trajectory approach. The LEPS potential energy surface is employed in the study, which is obtained from the ab initio results and has an early saddle point in the minimum energy path. The results indicate that the reaction product H2 is mainly scattered backward, and the reaction is found to occur via a direct channel. The product H2 is in a cold excitation of rotational state, but has a hot vibrational excitation. Based on the potential surface and the trajectory analysis, the reaction mechanism has been explained successfully.     

Mechanism of Cathode Process of B(Ⅲ) in LiF-NaF-KBF4 Melt by Electrochemical Titration Technique

The mechanism of cathode process of B(Ⅲ) at molybdenum and platinum electrodes in LiF-NaF-KBF₄ melt was studied and the transferred electron number of the reaction was calculated by means of cyclic voltammetry.The effect of adsorption of electroactive component on the electrochemical response (e.g., the voltammetric i─E curves) was analyzed and discussed. The "electrochemical spectra" for linear sweep voltammetry was used to elucidate the electrode reaction accompanied by a following transform process. The results show that the reduction of B(Ⅲ) to B(0) proceeds in reversible one step three-electron reaction and the cathode process of B(Ⅲ) is affected by product adsorbed strongly at the electrode surface. It is assumed that the reduction and deposition of B(Ⅲ) at molybdenum and platinum electrodes proceed in two kinds of mechanism: (1) B(Ⅲ)+ 3e = B_ads→ B (surface diffusion deposition mechanism) and (2) B(Ⅲ) + 3e = B (direct deposition mechanism).     

Phosphonylation and aging mechanisms of mipafox and butyrylcholinesterase: A theoretical study

Phosphonylation and aging processes between butyrylcholinesterase with mipafox have been studied at the B3LYP/6-311G(d,p) level of theory. The calculated results indicate that the phosphonylation process employs a two-step addition-elimination mechanism with the addition (the first step) as the rate-limiting step. Two different calculation models revealed that the catalytic triad of butyrylcholinesterase plays an important role in accelerating the reaction. This is the same mechanism as the phosphonylation reaction of acetylcholinesterase by sarin reported by Wang et al. However, the energy barrier of the rate-limiting step in the present reaction is higher than that in phosphonylation reaction of acetylcholinesterase by sarin. This indicates the differences in the phosphonylation activity of sarin and mipafox. The aging process occurs through a two-step addition-elimination mechanism similar to the phosphonylation process with the addition as the rate-limiting step. The solvent effects have been evaluated by using a CPCM model and the results show that the stationary structures and the negative charges around some important atoms involved in the two processes are not significantly different. However, the energy barrier of the phosphonylation process is remarkably decreased, revealing that this process is feasible in solution.     

Dynamical resonance in F＋H2 chemical reaction and rotational excitation effect

Reaction resonance is a frontier topic in chemical dynamics research,and it is also essential to the understanding of mechanisms of elementary chemical reactions.This short article describes an im- portant development in the frontier of research.Experimental evidence of reaction resonance has been detected in a full quantum state resolved reactive scattering study of the F H2 reaction.Highly accurate full quantum scattering theoretical modeling shows that the reaction resonance is caused by two Feshbach resonance states.Further studies show that quantum interference is present between the two resonance states for the forward scattering product.This study is a significant step forward in our understanding of chemical reaction resonance in the benchmark F H2 system.Further experimental studies on the effect of H2 rotational excitation on dynamical resonance have been carried out.Dy- namical resonance in the F H2(j=1)reaction has also been observed.     

Density functional theory calculation on the C―H bond insertion reaction of dibromocarbene with acetaldehyde

The insertion reaction mechanism of CBr_2 with CH_3CH_O has been studied by using the B3LYP/6-31G(d) method. The geometries of reactions, transition state and products were completely optimized. All the energy of the species was obtained at the CCSD(T)/6-31G(d) level. All the transition state is verified by the vibrational analysis and the internal reaction coordinate (IRC) calculations. The results show that the propionaldehyde (~HP1) is the main product of CH_2 insertion with CH_3CH_O. The calculated results indicated that all the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CBr_2 not only can insert the C_α-H [reaction I(1)]) but also can react with C_β-H [reaction II(1)]. The statistical thermodynamics and Eyring transition state theory with Wigner correc- tion are used to study the thermodynamic and kinetic characters of I(1) and II(1) in temperature range from 100 to 2200 K. The results show that the appropriate reaction temperature rang is 250 to 1750 K and 250 to 1600 K at 1.0 atm for I(1) and II(1) respectively. The rate constant and equilibrium constant are distinct in the range from 250 to 1000 K so that I(1) more easily occurs, while the reactions are not selected in the temperature range of 1000-1600 K     

Oxidation behavior of artificial magnetite pellets

The oxidation behavior of artificial magnetite pellets was investigated through measurements of the oxidation degree and mineralogical analysis. The results show that artificial magnetite pellets are much easier to oxidize than natural magnetite. The oxidation is controlled through two different reaction mechanisms. The oxidation of artificial magnetite is dominated by internal diffusion, with an activation energy of 8.40 kJ/mol, at temperatures less than 800℃, whereas it is controlled by chemical reaction, with a reaction activation energy of 67.79 kJ/mol, at temperatures greater than 800℃. In addition, factors such as the oxygen volume fraction and the pellet diameter strongly influence the oxidation of artificial magnetite:a larger oxygen volume fraction and a smaller pellet diameter result in a much faster oxidation process.     

Density functional theory calculation on the C―H bond insertion reaction of dibromocarbene with acetaldehyde

The insertion reaction mechanism of CBr2 with CH3CHO has been studied by using the B3LYPI6-31G（d） method. The geometries of reactions, transition state and products were completely optimized. All the energy of the species was obtained at the CCSD（T）/6-31G（d） level. All the transition state is verified by the vibrational analysis and the internal reaction coordinate （IRC） calculations. The results show that the propionaldehyde （Hp1） is the main product of CH2 insertion with CH3CHO. The calculated results indicated that all the major pathways of the reaction were obtained on the singlet potential energy surface. The singlet CBr2 not only can insert the Cα-H [reaction I（1）]） but also can react with Cβ-H [reaction l1（1）]. The statistical thermodynamics and Eyring transition state theory with Wigner correc-tion are used to study the thermodynamic and kinetic characters of I（1） and I1（1） in temperature range from 100 to 2200 K. The results show that the appropriate reaction temperature rang is 250 to 1750 K and 250 to 1600 K at 1.0 atm for I（1） and I1（1） respectively. The rate constant and equilibrium constant are distinct in the range from 250 to 1000 K so that I（1） more easily occurs, while the reactions are not selected in the temperature range of 1000-1600 K.     

人工闪锌矿氧压酸浸过程中Cu2+的催化机理研究

The potential autoclave was used to study the catalytic mechanism of Cu2+ during the oxygen pressure leaching process of artificial sphalerite. By studying the potential change of the system at different temperatures and the SEM–EDS difference of the leaching residues, it was found that in the temperature range of 363–423 K, the internal Cu2+ formed a CuS deposit on the surface of sphalerite, which hindered the leaching reaction, resulting in a zinc leaching rate of only 51.04%. When the temperature exceeds 463 K, the system potential increases steadily. The increase in temperature leads to the dissolution of the CuS, which is beneficial to the circulation catalysis of Cu2+. At this time, the leaching rate of Zn exceeds 95%. In addition, the leaching kinetics equations at 363–423 and 423–483 K were established. The activation energy of zinc leaching at 363–423 and 423–483 K is 38.66 and 36.25 kJ/mol, respectively, and the leaching process is controlled by surface chemical reactions.     

Alkylation of toluene with 1,3-pentadiene over silica supported aluminum chloride catalyst in an extracting-distilling reactor

The alkylation of toluene with 1,3-pentadiene to produce pentyltoluene is designed to obtain 2,6-dimethylnaphalene for the monomer production of 2,6-naphthalene dicarboxylic acid. The possibility of the reaction is examined by the thermodynamics of the alkylation reaction using Thinh’s group contributions method, and tested over silica supported aluminum chloride catalyst in a newly developed extracting?distilling reactor. The thermodynamics calculation results show that the alkylation reaction is exothermic and can proceed at 298?350 K under normal pressure with an equilibrium constant higher than 106. Based on the thermodynamic calculation and the properties of the reactants and product, the extracting-distilling reactor was designed to allow 1,3-pentadiene to react with toluene at much lower temperature than the boiling point of toluene at the catalyst site. The alkylation product, which has a higher boiling point than that of toluene, is transferred from the catalytic site into the toluene bath and collected. The experimental results show that the reactor functions as designed and promotes the selectivity of the alkylation reaction close to 100%. The effect of raw material ratio of toluene to 1,3-pentadiene and reaction time are discussed in this paper. The suitable catalytic reaction conditions are as follows: at reaction temperature of 338 K and ambient pressure, the reactant ratio of toluene to 1,3-pentadiene is 5:1 for a six-hour reaction.     

Continental subduction channel processes: Plate interface interaction during continental collision

The study of subduction-zone processes is a key to development of the plate tectonic theory. Plate interface interaction is a basic mechanism for the mass and energy exchange between Earth＇s surface and interior. By developing the subduction channel model into continental collision orogens, insights are provided into tectonic processes during continental subduction and its products. The continental crust, composed of felsic to mafic rocks, is detached at different depths from subducting continental lithosphere and then migrates into continental subduction channel. Part of the subcontinental lithospheric mantle wedge, composed of perido- tile, is offscrapped from its bottom. The crustal and mantle fragments of different sizes are transported downwards and upwards inside subduction channels by the corner flow, resulting in varying extents of metamorphism, with heterogeneous deformation and local anatexis. All these metamorphic rocks can be viewed as tectonic melanges due to mechanical mixing of crust- and man- lie-derived rocks in the subduction channels, resulting in different types of metamorphic rocks now exposed in the same orogens. The crust-mantle interaction in the continental subduction channel is realized by reaction of the overlying ancient subcontinental lithospheric mantle wedge peridotite with aqueous fluid and hydrous melt derived from partial melting of subducted continental basement granite and cover sediment. The nature of premetamorphic protoliths dictates the type of collisional orogens, the size of ultrahigh-pressure metamorphic terranes and the duration of ultrahigh-pressure metamorphism.     

Theoretical study on the mechanism of cycloaddition between dimethyl methylene carbene and acetone

The mechanism of the cycloaddition reaction of singlet dimethyl methylene carbene and acetone has been studied by using second-order Moller-Plesset perturbation and density functional theory. The geometrical parameters, harmonic vibrational frequencies and energy of stationary points on the potential energy surface are calculated by MP2/6-31G and B3LYP/6-31G methods. The results show that path b of the cycloaddition reaction （1） would be the major reactive channel of the cycloaddition reaction between singlet dimethyl methylene carbene and acetone, which proceeds in two steps： i） The two reactants form an energy-rich intermediate （INT1b）, which is an exothermic reaction of 23.3 kJ/mol with no energy barrier. ii） The intermediate INT1b isomerizes to a three.membered ring product （P1） via transition state TS1b with energy barrier of 22.2 kJ/mol. The reaction rate of this reaction and its competitive reactions do greatly differ, with excellent selectivity. In view of dynamics and thermodynamics, this reaction is suitable for occurring at 1 atm and temperature range of 300-800 K, in which the reaction will have not only the larger spontaneous tendency and equilibrium constant but also the faster reaction rate.     

Synergistic effect of microwave irradiation and CaF_2 on vanadium leaching

The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride(Ca F_2) on the vanadium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when Ca F_2 is present. The leaching rate of vanadium under microwave irradiation is increased by 8%–15% when 5wt% Ca F_2 is added; by contrast,in the absence of Ca F_2,the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation,whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover,a large amount of Al and V and a small amount of Si are dissolved from samples under microwave heating,as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When Ca F_2 is present,the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer,resulting in a prominent effect of microwave irradiation.     

Transverse vibration of the blade for unmanned micro helicopter using rayleigh-ritz method

A rotor manipulation mechanism for micro unmanned helicopter utilizing the inertia and the elasticity of the rotor is introduced. The lagging motion equation of the rotor blades is established, and then the natural frequencies and mode shapes of the blade for the helicopter are studied by using beam characteristic orthogonal polynomials by the Rayleigh-Ritz method. The variation of natural frequencies with the speed of rotation and the mode shapes at different rotational speeds are plotted. The using of orthogonal polynomials for the bending shapes enables the computation of higher natural frequencies of any order to be accomplished without facing any difficulties.     

基于能源枢纽的钢铁制造过程多能源协同优化

The production process of iron and steel is accompanied by a large amount of energy production and consumption. Optimal scheduling and utilization of these energies within energy systems are crucial to realize a reduction in the cost, energy use, and CO₂ emissions. However, it is difficult to model and schedule energy usage within steel works because different types of energy and devices are involved. The energy hub (EH), as a universal modeling frame, is widely used in multi-energy systems to improve its efficiency, flexibility, and reliability. This paper proposed an efficient multi-layer model based on the EH concept, which is designed to systematically model the energy system and schedule energy within steelworks to meet the energy demand. Besides, to simulate the actual working conditions of the energy devices, the method of fitting the curve is used to describe the efficiency of the energy devices. Moreover, to evaluate the applicability of the proposed model, a case study is conducted to minimize both the economic operation cost and CO₂ emissions. The optimal results demonstrated that the model is suitable for energy systems within steel works. Further, the economic operation cost decreased by 3.41%, and CO₂ emissions decreased by approximately 3.67%.     

The v-v energy transfer of highly vibrationally excitedstates (Ⅱ)──Vibrational quenching of CO(v) by H_2O

The vibrational energy transfer from highly vibrationally excited CO to H 2O molecules is studied by time-resolved Fourier transform infrared emission spectroscopy (TR FTIR). Following the 193 nm laser photolysis of CHBr 3 and O 2 the secondary reactions generate CO(v). The infrared emission of CO(v→v-1) is detected by TR FTIR. The excitation of H 2O molecules is not observed. By the method of the spectral simulation and the differential technique, 8 rate constants for CO(v)/H 2O system are obtained: (1.7±0.1), (3.4±0.2), (6.2±0.4), (8.0±1.0), (9.0±2.0), (12±3), (16±4) and (18±7) (10 -13cm 3·molecule -1·s -1). At least two reasons lead to the efficient energy transfer. One is the contributions of the rotational energy to the vibational energy defect and the other is the result of the complex collision. With the SSH and ab initio calculations, the quenching mechanism of CO(v) by H 2O is suggested.     

Effect of H2S concentration on the corrosion behavior of pipeline steel under the coexistence of H2S and CO2

The effect of H2S concentration on H2S/CO2 corrosion of API-X60 steel was studied by scanning electron microscopy, a weight-loss method, potentiodynamic polarization tests, and the electrochemical impedance spectroscopy technique. It is found that the cor-rosion process of the steel in an environment where H2S and CO2 coexist at different H2S concentrations is related to the morphological structure and stability of the corrosion product film. With the addition of a small amount of H2S, the size of the anode reaction region is de-creased due to constant adsorption and separation of more FeS sediment or more FeHS＋ions on the surface of the steel. Meanwhile, the dou-ble-layer capacitance is diminished with increasing anion adsorption capacity. Therefore, the corrosion process is inhibited. The general cor-rosion rate of the steel rapidly decreases after the addition of a small amount of H2S under the coexistence of H2S and CO2. With a further increase in H2S concentration, certain parts of the corrosion product film become loose and even fall off. Thus, the protection provided by the corrosion product film worsens, and the corrosion rate tends to increase.     

Synergistic effect of microwave irradiation and CaF<Subscript>2</Subscript> on vanadium leaching

The effect and mechanism of microwave irradiation on vanadium leaching were studied via a comparison between microwave heating and conventional heating. The results show a synergistic effect of microwave irradiation and calcium fluoride (CaF₂) on the vanadium leaching efficiency. It is confirmed that the vanadium leaching process can be improved by microwave irradiation when CaF₂ is present. The leaching rate of vanadium under microwave irradiation is increased by 8%-15% when 5wt% CaF₂ is added; by contrast, in the absence of CaF₂, the leaching rate is almost unaffected compared to that by conventional heating. Morphological analysis reveals that the particles are gradually eroded by acid under microwave irradiation, whereas some of the fine particles in samples subjected to conventional heating are tightly covered by a flocculent silicate product. Moreover, a large amount of Al and V and a small amount of Si are dissolved from samples under microwave heating, as revealed by the elemental analysis of leachates. Fourier transform infrared spectroscopic analysis also indicates a higher mass transfer coefficient in the diffusion layer of the raw material by microwave irradiation. When CaF₂ is present, the reaction energy barrier is lowered and the leaching process is controlled by the tightly covered product layer, resulting in a prominent effect of microwave irradiation.     

Theoretical analysis of reactive solid-liquid interfacial energies

The characterization of reactive solid-liquid interfacial energies and solid surface energies is a pressing problem in materials science and surface science. Based on the concept that unbalanced forces doing work, a mathematical formulation between surface energies and interfacial energies for reactive wetting is presented. The resulting formalism has significant generality in which the equilibrium Young’s equation for solid-liquid interfacial energies is just a special case. It is shown that a solid-liquid interfacial energy at non-equilibrium is always higher than that at equilibrium, and that the transformation of reactive interfaces to equilib-rium interfaces is an inevitable, spontaneous process. The numerical range of solid-liquid interfacial energies γsl for a limited, solid-liquid interfacial wetting system was calculated to be 0 ≤γsl ≤γsg. The calculation methods for reactive solid-liquid interfacial energies and solid surface energies are presented. They are significant for composite materials and weld, powder sinter, package of electronic devices, and other surface and interfacial issues in metallurgy.     

Mechanism of skeletal reorganization of 1,6-enynes catalyzed by GaCl<Subscript>3</Subscript>

The mechanism of skeletal reorganization of 1,6-enynes catalyzed by GaCI3 has been studied with the density functional method at the B3LYP/6-31G* level. The structures and energies of the stationary points were calcu-lated to identify the activation barriers. The transition stateswere testified with vibration analysis and IRC calculations.The results of calculation show that the conversion of 1,6-enynes is a step-wise reaction. The whole reaction process is formation and migration of three-membered cycle involvinga three-center and two-electron (3c-2e) bond. High stereose-lectivity of the reaction is in good agreement with experimental results.     

Bogie's Rotational Resistance Coefficient Analysis Based on Novel Parallel Mechanism

In this paper,a novel parallel mechanism which can be used to evaluate body-to-bogie yawtorque is proposed.It can satisfy experimental testing for rotation resistance coefficient(RRC) with various types of bogies,different rotational speeds,and different states of air spring.Aiming at the problem that computing speed of Newton iterative method for solving rotational angle is incompetence to meet the real-time requirements,and also that other methods adopting physical device such as laser displacement sensor to solve rotational angle possess larger measurement error,the analytical techniques method used for solving rotational angle is presented.Finally,by using the upper-single-6-DOF motion platform as an authentic urging mean to simulate a real vehicle,the test was carried out under the speeds of 0.2 and 1.0(°)/s,with the air spring at the inflated and deflated states,respectively.The results showthat the RRC of the bogie under various conditions is less than 0.06,which meets the standard requirement EN-14363.It was also found that the speed of vehicles moving along curves and the state of air spring were key factors influencing the RRC.The feasibilities of this model and test method are verified in this study.