Effect of Vacancy Defects on the Properties of CoS_(2) and FeS_(2)

In order to explore the effect of vacancy defects on the structural,electronic,magnetic and optical properties of CoS_(2) and FeS_(2),first-principles calculation method was used to investigate the alloys.The calculated results of materials without vacancy are consistent with those reported in the literatures,while the results of materials with vacancy defect were different from those of literatures due to the difference vacancy concentration.The Co vacancy defect hardly changes the half-metallic characteristic of CoS_(2).The Fe vacancy defect changes FeS_(2) from semiconductor to half-metal,and the bottom of the spin-down conduction band changes from the p orbital state of S to the d(t_(2g))orbital state of Fe,while the top of the valence band remains the d orbital d(eg)state of Fe.The half-metallic Co vacancy defects of CoS_(2) and Fe vacancy defects of FeS_(2) are expected to be used in spintronic devices.S vacancy defects make both CoS_(2) and FeS_(2) metallic.Both the Co and S vacancy defects lead to the decrease of the magnetic moment of CoS_(2),while both the Fe and S vacancy defects lead to the obvious magnetic property of FeS_(2).Vacancy defects enhance the absorption coefficient of infrared band and long band of visible light obviously,and produce obvious red shift phenomenon,which is expected to be used in photoelectric devices.

An efficient and mild recycling of waste melamine formaldehyde foams by alkaline hydrolysis

Melamine formaldehyde foam(MFF)generates many poisonous chemicals through the traditional recycling methods for organic resin wastes.Herein,a high MFF degradation ratio of ca.97 wt.%was achieved under the mild conditions(160℃)in a NaOH–H2O system with ammelide and ammeline as the main degradation products.The alkaline solvent had an obvious corrosion effect for MFF,as indicated by scanning electron microscopy(SEM).The reaction process and products distribution were studied by Fourier-transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),and ^(13)C nuclear magnetic resonance(NMR).Besides,the MFF degradation products that have the similar chemical structures and bonding performances to those of melamine can be directly used as the raw material for synthesis of melamine urea-formaldehyde resins(MUFs).Moreover,the degradation system demonstrated here showed the high degradation efficiency after reusing for 7 times.The degradation process generated few harmful pollutants and no pre-or post-treatments were required,which proves its feasibility in the safe removal or recovery of waste MFF.

Novel transmission property of zero-index metamaterial waveguide doped with gain and lossy defects

Taking inspiration from quantum parity–time(PT) symmetries that have gained immense popularity in the emerging fields of non-Hermitian optics and photonics, the interest of exploring more generalized gain-loss interactions is never seen down. In this paper we theoretically present new fantastic properties through a zero-index metamaterial(ZIM) waveguide loaded gain and loss defects. For the case of epsilon-and-mu-near-zero(EMNZ) based ZIM medium, electromagnetic(EM)waves are cumulative and the system behaves as an amplifier when the loss cavity coefficient is greater than the gain cavity coefficient. Conversely, when loss is less than gain, EM waves are dissipated and the system behaves as an attenuator.Moreover, our investigation is extended to non-Hermitian scenarios characterized by tailored distributions of gain and loss in the epsilon-near-zero(ENZ) host medium. The transport effect in ZIM waveguide is amplified in one mode, while it is dissipative in the other mode, which breaks the common sense and its physic is analyzed by magnetic flux. That is which cavity has the smaller loss/gain coefficient, the larger its magnetic flux, which cavity dominates. This paper is of significant importance in the manipulation of electromagnetic waves and light amplification as well as the enhancement of matter interactions.

Oxidation of glyoxal to glyoxylic acid by oxygen over V_2O_5/C catalyst

A novel vanadium oxide catalyst supported on active carbon was prepared by an incipient wetness impregnation method, and the precursor was obtained from oxalic acid aqueous solutions of NH4VO3. The catalyst was applied liquid phase oxidation of glyoxal to glyoxylic acid. It was found that V2O5/C catalyst exhibited obvious activity for glyoxal oxidation. Glyoxylic acid could be obtained without pH regulation during the reaction. By using this catalyst, the conversion of glyoxal and the yield of glyoxalic acid were 29.2% and 13.6%, respectively at 313 K and oxygen flow 0.1 L/rain after reaction for 10 h.

Numerical Simulation and Experimental Research on Microstructural Evolution During Compact Hot Extrusion of Heavy Caliber Thick-Wall Pipe

Compact hot extrusion(CHE) process of heavy caliber thick-wall pipe is a new material-saving production process. In order to reveal the optimum hot extrusion parameters in CHE process, the e ects of the extrusion parameters on the microstructural evolution are investigated systematically. The metadynamic recrystallization(MDRX) kinetic models and grain size models of as-cast P91 steel are established for the first time according to the hot compression tests performed on the Gleeble-3500 thermal-simulation machine. Then a thermal-mechanical and micro-macro coupled hot extrusion finite element(FE) model is established and further developed in DEFORM software. The results indicated that the grain size of the extruded pipe increases with the increasing of initial temperature and extrusion speed, decreases when extrusion ratio increases. Moreover, the grain size is more sensitive to the initial temperature and the extrusion ratio. The optimum hot extrusion parameters are including that, the initial extrusion temperature of 1250 °C, the extrusion ratio of 9 and the extrusion speed of 50 mm/s. Furthermore, in order to verify the simulation precisions, hot extrusion experiment verification on the heavy caliber thick-wall pipe is carried out on the 500 MN vertical hot extrusion equipment. The load–displacement curve of the extrusion process and the grain sizes of the middle part extruded pipe are in good accuracy with the simulation results, which confirms that the hot extrusion FE models of as-cast P91 steel could estimate the hot extrusion behaviors. The proposed hot extrusion FE model can be used to guide the industrial production research of CHE process.

MONOMER REACTIVITY RATIO AND THERMAL PERFORMANCE OFα-METHYL STYRENE AND GLYCIDYL METHACRYLATE COPOLYMERS

Synthesis and characterization of the copolymers （PAG） of α-methyl styrene （AMS） and glycidyl methacrylate （GMA） are presented. The copolymers of PAG were characterized by gel permeation chromatography （GPC）, Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （^1H-NMR） and thermogravimetery （TG）. Based on the copolymer compositions determined by ^1H-NMR, the reactivity ratios of AMS and GMA were found to be 0.105 ± 0.012 and 0.883 ± 0.046 respectively by Kelen-Tudos method. TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures. Under heating, the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions.

Degradation analysis of A^2/O combined with AgNO3 + K2FeO4 on coking wastewater

In this work, a coking wastewater was selected and a biochemical A^2/O treatment device for fractional degradation was designed and employed. After each stage of the treatment, the products were analyzed through gas chromatography–mass spectroscopy(GC–MS) to determine their composition. Finally, AgNO_3+ K_2 FeO_4 was used as an advanced deep catalytic oxidation treatment. It was concluded from the analysis that cyclic organics could be degraded and the chemical oxygen demand(COD) was controlled within 50 mg·L^(-1), in line with the target value. Meanwhile, the spectra obtained from the GC–MS were in accordance with the conclusions reached based on the COD. The research results showed that all hard-degradable organics in coking wastewater could be eliminated through the A^2/O bio-membrane treatment and the advanced treatment of making use of K_2FeO_4 as an oxidant and Ag+as a catalyst, the catalytic efficiency with Ag+as a catalyst of K+2FeO_4 was very high. Agcould evidently improve the oxidation capacity of K_2FeO_4 to wastewater in its short stability time, and this is an important innovation.

Fabrication and characterization of mussel-inspired layer-by-layer assembled CL-20-based energetic films via micro-jet printing

Three-dimensional(3D)micro-jet printing is a droplet deposition technique based on liquid-phase materials.To improve the deposition density and performance of energetic films with micro/nanoscale on an energetic chip,polydopamine(PDA)was utilized as a linker bridge to induce the in-situ self-assembly of CL-20-based energetic film via 3D micro-jet printing.The self-assembly was extensively characterized by confocal laser scanning microscopy(CLSM),SEM,power-XRD,XPS,and DSC.The performance of the self-assembled film was verified by the mechanical properties and detonation properties,and a possible self-assembly mechanism in the layer-by-layer micro-jet printing process was proposed.The results indicated PDA-induced self-assembly enhanced the physical entanglement between the binders and energetic crystal,reduced the porosity from 15.87%to 11.28%,and improved the elastic modulus and the detonation performance of the CL-20-based energetic film.This work proposes a novel and promising energetic film design and fabrication strategy to enhance the interaction between the energetic composite layers in the micro-jet printing process.

Broad-Band FMR Linewidth of Co_2MnSi Thin Films with Low Damping Factor:The Role of Two-Magnon Scattering

The low Gilbert damping factor, which is usually measured by ferromagnetic resonance, is crucial in spintronic applications. Two-magnon scattering occurs when the orthogonMity of the ferromagnetic resonance mode and other degenerate spin wave modes was broken by magnetic anisotropy, voids, second phase, surface defects, etc., which is important in analysis of ferromagnetic resonance linewidth. Direct fitting to linewidth with Gilbert damping is advisable only when the measured linewidth is a linear function of measuring frequency in a broad band measurement. We observe the nonlinear ferromagnetic resonance linewidth of Co2MnSi thin films with respect to measuring frequency in broad band measurement. Experimental data could be well fitted with the model including two-magnon scattering with no fixed parameters. The fitting results show that two-magnon scattering results in the nonlinear linewidth behavior, and the Gilbert damping factor is much smaller than reported ones, indicating that our Co2MnSi films are more suitable for the applications of spin transfer torque.

Control synthesis of linear distributed parameter switched systems

The control synthesis for switched systems is extended to distributed parameter switched systems in Hilbert space. Based on semigroup and operator theory, by means of multiple Lyapunov method incorporated average dwell time approach, sufficient con- ditions are derived in terms of linear operator inequalities frame- work for distributed parameter switched systems. Being applied to one dimensional heat propagation switched systems, these lin- ear operator inequalities are reduced to linear matrix inequalities subsequently. In particular, the state feedback gain matrices and the switching law are designed, and the state decay estimate is explicitly given whose decay coefficient completely depends on the system＇s parameter and the boundary condition. Finally, two numerical examples are given to illustrate the proposed method.

A novel sensor of potassium ions based on mode-filtered light detection

A novel potassium ions sensor based on mode-filtered light detection was reported. The analyzer was consisting of an optical fiber immobilized with a dye of bromocresol green and a fused-silica capillary. It was found that mode-filtered light intensity decreased with the concentration of potassium ions and a linear detection range of 0.25-20 mmol/L （R^2 = 0.9977） was obtained with a detection limit of 9 ×10^-5 mol/L as well as fast response, good reproducibility and reversibility in the working concentration range.

Enhancement effect of Mn doping on Co_(3)O_(4)derived from Co-MOF for toluene catalytic oxidation

The design of Co-Mn composite oxides catalysts derived from MOF is significant for catalytic combustion of toluene.Here,a series of M-CoaMnfbOx,with enhanced catalytic properties compared with that of MCo_(3)O_(4),were successfully prepared through pyrolysis of Mn-doped Co-MOF.The as-synthesized MCo1Mn1Ox(Co:Mn=1:1)exhibits an optimal catalytic activity with 90%toluene conversion reached at227℃,which benefits from the increase of Co^(3+),Oadsand the synergistic effect between Mn and Co.According to the analysis of the in situ diffuse reflectance infrared Fourier transform spectroscopy,toluene could be degraded easier on M-Co1Mn1Oxwith lower activation energy than M-Co_(3)O_(4).The main intermediate products are benzaldehyde,benzoic acid,anhydride,and maleate species.Those findings reveal the value of Mn doping for improved activity of toluene oxidation on MOF derived Co_(3)O_(4),which provide a feasible method for the construction of toluene-oxidation catalysts.

Syntheses, Structures and Properties of Three Novel La(Ⅲ)/Co(Ⅱ) Coordination Polymers Based on 5-(3-(Tetrazo-5-yl)phenyl)isophthalic Acid

Three novel complexes, namely {[La(tapipa)(4,4′-bibp)·(H2O)2]·H2O}n(1),{[La-(tapipa)(H2O)4(OH)]·3 H2O}n(2),[Co(tapipa)(1,4-bbib)]n(3)(tapipa = 5-(3-(tetrazo-5-yl)phenyl)isophthalic acid, 4,4′-bibp = 4,4′-bis(imidazolyl)biphenyl, and 1,4-bbib = 1,4-bis(benzimidazo-1-ly)benzene) have been synthesized under solvothermal conditions and characterized by PXRD, IR,TGA, and so on. Complex 1 presents a 2 D layer structure, which is finally packed into a 3 D supramolecular structure by means of hydrogen bonds;complexes 2 and 3 exhibit 1 D chains and 2 D wavy-type structures, respectively, which are expanded into 3 D supramolecular structures through hydrogen bonds and π-π interactions. Furthermore, the luminescence properties of complex 1 and the variable-temperature magnetic susceptibilities of 3 were investigated. Complex 1 has highly selective sensing for Fe^3+ and Cr2O7^2- ions.

Effect of Fiber Volume Fraction on Longitudinal Tensile Properties of SiCf/Ti-6Al-4V Composites

The longitudinal tensile properties of SiCf/Ti-6Al-4V composites with different fiber volume fractions were simulated by the Monte Carlo 2-D finite element model. The random distribution of fiber strength was expressed by the two-parameter Weibull function. Meanwhile, contact elements and birth-death elements were used to describe the interfacial sliding process after debonding and fiber breakage（or matrix cracking） respectively, which was realized by subroutine complied in ANSYS-APDL（ANSYS Parametric Design Language）. The experimental results show that the yield stress and ultimate tensile strength of SiCf/Ti-6Al-4V composites increase with increasing fiber volume fraction, while the corresponding strain of them is just on the contrary. In addition, almost the same failure mode is obtained in SiCf/Ti-6Al-4V composites with various fiber volume fractions when the interfacial shear strength is fixed. Finally, the tensile strength predicted by finite element analysis is compared with that predicted by Global load-sharing model, Local load-sharing model and conventional rule of mixtures, thus drawing the conclusion that Local load-sharing model is very perfect for the prediction of the ultimate tensile strength.

Real-time dynamics in strongly correlated quantum-dot systems

We investigate the real-time dynamical properties of Rabi-type oscillation through strongly correlated quantum-dot systems by means of accurate hierarchical equations of motion.It is an extension of the hierarchical Liouville-space approach for addressing strongly correlated quantum-dot systems.We study two paradigmatic models,the single quantum-dot system,and serial coupling double quantum-dot system.We calculate accurately the time-dependent occupancy of quantum-dot systems subject to a sudden change of gate voltage.The Rabi-type oscillation of the occupancy and distinct relaxation time of the quantum-dot systems with different factors are described.This is helpful to understand dissipation and decoherence in real-time dynamics through nanodevices and provides a theoretical frame to experimental investigation and manipulation of molecular electronic devices.

Efficient adsorption separation of methane from C_(2)-C_(3) hydrocarbons in a Co(Ⅱ)-nodes metal-organic framework

Methane(CH_(4))as a substitute for other mineral fuels plays a crucial role in reducing energy consumption and preventing environmental pollution.The present study employs a solvothermal method to fabricate a porous framework Co-metal-organic framework(Co-MOF)containing two distinct secondary building units(SBUs):an anionic[Co_(2)(μ_(2)-OH)(COO)_(4)(H_(2)O)]and a neutral[CoN_(2)(COO)_(2)].Notably,within the anionic SBUs,the coordinated water molecules induce the generation of divergent unsaturated Co(Ⅱ)centers in the unidirectional porous channels,thereby creating open metal sites.The adsorption performance of Co-MOF towards pure component gases was systematically investigated.The results demonstrated that Co-MOF exhibits superior adsorption capacity for C_(2)-C_(3) hydrocarbons compared to CH_(4),which offers the potential for efficient adsorption and separation of CH_(4) from C_(2)-C_(3) hydrocarbons.The gas selectivity separation ratios of Co-MOF for C_(2)H_(6)/CH_(4) and C_(3)H_8/CH_(4) were calculated using the ideal adsorbed solution theory method at 273/298 K and 0.1 MPa.The results revealed that Co-MOF achieved remarkable equilibrium separation selectivity for CH_(4) and C_(2)-C_(3) hydrocarbon gases among non-modified MOFs,signifying the potential of the synthesized Co-MOF for efficient recovery and purification of CH_(4) from C_(2)-C_(3) hydrocarbons.Breakthrough experiments further demonstrate the ability of Co-MOF to purify methane from C_(2)-C_(3) hydrocarbons in practical gas separation scenarios.Additionally,molecular simulation calculations further substantiate the propensity of anionic SBUs to interact with C_(2)-C_(3) hydrocarbon compounds.This study provides a novel paradigm for the development of porous MOF materials in the application of gas mixture separation.

污泥和秸秆廉价吸附剂对酸性大红3R的吸附动力学和热力学研究(英文)

A low-cost adsorbent was prepared from sludge and straw by pyrolysis in a dried state with the surface area of the adsorbent of 829.49 m2·g?1,micropore volume of 0.176 cm2·g?1 and average pore radius of 5.0 nm.The kinetic,equilibrium isotherm and thermodynamic characteristics of trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4′,6,8-trisulphonate(acid scarlet 3R)onto the adsorbent from sludge and straw were investigated.The results indicated that the pseudo second order adsorption was the predominant adsorption mechanism of acid scarlet 3R.Thus,the adsorption phenomenon was suggested as a chemical process.The adsorption data were fitted better with Langmuir model than Freundlich model,indicating that the adsorption of acid scarlet 3R belonged to the monolayer adsorption and mainly occurred in micropores.

The Analytical Expressions for Computing the Minimum Distance between a Point and a Torus

In this paper, we present the analytical expressions for computing the minimum distance between a point and a torus, which is called the orthogonal projection point problem. If the test point is on the outside of the torus and the test point is at the center axis of the torus, we present that the orthogonal projection point set is a circle perpendicular to the center axis of the torus;if not, the analytical expression for the orthogonal projection point problem is also given. Furthermore, if the test point is in the inside of the torus, we also give the corresponding analytical expression for orthogonal projection point for two cases.

Collision difference between Kerr spatial solitons and nonlinear Kerr spatial solitons

In order to study the collision of the Kerr solitons and the collision of the the nonlinear Kerr solitons,numerical simulation is employed and it is found that the collision of solutions is different.The collision of Kerr solution is periodically elastic while the collision of the the nonlinear Kerr solution is strongly inelastic.Periodic collisions of the Kerr solitons can be changed by changing the relative amplitude while the collisions of nonlinear the Kerr solitons can be adjusted by selecting the appropriate relative phase.

A graphitized expanded graphite cathode for aluminum-ion battery with excellent rate capability

Aluminum-ion battery(AIB)is very promising for its safety and large current charge–discharge.However,it is challenging to build a high-performance AIB system based on low-cost materials especially cathode&electrolyte.Despite the low-cost expanded graphite-triethylaminehydrochloride(EG-ET)system has been improved in cycle performance,its rate capability still remains a gap with the expensive graphene-alkylimidazoliumchloride AIB system.In this work,we treated the cheap EG appropriately through an industrial high-temperature process,employed the obtained EG3K(treated at 3000℃)cathode with AlCl_(3)-ET electrolyte,and built a novel,high-rate capability and double-cheap AIB system.The new EG3K-ET system achieved the cathode capacity of average 110 m Ah g^(-1)at 1 A g^(-1)with 18,000cycles,and retained the cathode capacity of 100 m Ah g^(-1)at 5 A g^(-1)with 27,500 cycles(fast charging of 72 s).Impressively,we demonstrated that a battery pack(EG3K-ET system,12 m Ah)had successfully driven the Model car running 100 m long.In addition,it was confirmed that the improvement of rate capability in the EG3K-ET system was mainly derived by deposition,and its capacity contribution ratio was about 53.7%.This work further promoted the application potential of the low-cost EG-ET AIB system.