Mixed grain structure and mechanical property anisotropy of AZ40 magnesium alloy bar with diameter of 160 mm

The mixed grain structure and mechanical property anisotropy of AZ40 magnesium alloy bar with a diameter of 160 mm manufactured by ＂multi-direction forging（MDF） ＋ extrusion ＋ online cooling＂ technique were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, X-ray diffraction macro-texture measurement and room temperature（RT） tensile test. The results show that mixed grain structure is caused by the micro-segregation of Al in semi-continuous casting ingot. Homogenization of（380 °C, 8 h） ＋（410 °C, 12 h） cannot totally eliminate such micro-segregation. During MDF and extrusion, the dendrite interiors with 3%-4% Al（mass fraction） transform to fine grain zones, yet the dendrite edges with about 6% Al transform to coarse grain zones. XRD macro-textures of the outer, R/2 and center show typical fiber texture characteristics and the intensity of [0001]//Ra D orientation in the outer（11.245） is about twice as big as those in the R/2（6.026） and center（6.979）. The as-extruded AZ40 magnesium alloy bar has high elongation（A） and moderate ultimate tensile strength（Rm） in both extrusion direction（ED） and radius direction（Ra D）, i.e., A of 19%-25% and Rm of 256-264 MPa; however, yield strength（Rp0.2） shows anisotropy and heterogeneity, i.e., 103 MPa in Ra D, 137 MPa in ED-C（the center） and 161 MPa in ED-O（the outer）, which are mainly caused by the texture.（155 °C, 7 h） ＋（170 °C, 24 h） aging has no influence on strength and elongation of AZ40 magnesium bar.

Preparation and structure characteristics of nano-Bi_2O_3 powders with mixed crystal structure

The nano-Bi2O3 powders were prepared by a chemical precipitation method with Bi（NO3）3, HNO3 and NaOH as reactants. The structural characteristics and morphology of nano-Bi2O3 powders were investigated by X-ray diffraction and transmission electron microscopy, respectively. The results show that under the optimum condition that 300g/L Bi（NO3）3 reacts at 90℃ for 2h, the Bi2O3 powders with 60nm on the average and 99.5% in purity are obtained. The prepared nano-Bi2O3 powders contain a mixed crystal structure of monoclinic and triclinic instead of traditional structure of monoclinic α-Bi2O3. And the mixed crystal structure is stable in air. The reason for the appearance of the mixed crystal structure may be that the ionic radius ratio of Bi 3+ to O 2- changes easily during the formation of nano-Bi2O3 particles by a chemical precipitation method.

HRTEM Study of Three New Regularly Mixed-layer Structures of B_8S_6 Type in Ca-RE Fluorocarbonate Minerals

The microstructural features of clacium rare earth(Ca RE) fluorocarbonate minerals from Southwest China were studied by using selected area electron diffraction(SAED) and high resolution transmission electron microscopy(HRTEM). Three new regularly mixed layer structures of B 8S 6 type with long period and different stacking sequence, i.e. B 8S 6 Ⅰ, B 8S 6 Ⅱ, and B 8S 6 Ⅲ, were found in the derived polycrystal of parisite, in which their structural symmetry, cell parameters, chemical formulas of crystal and stacking models of structural unit layer, etc. were determined. The results of this study also show that these new regularly mixed layer structrues were formed by order stacking unit layer of bastnaesite(B) and synchisite(S) in varying proportion along c axis. The observation under HRTEM reveals that in the three new regularly mixed layer structures there are different distribution modes of Ce F ion layers, CO 2- 3 ion groups between the Ce F ion layers, and CO 2- 3 ion groups between Ce F and Ca 2+ ion layers, and there are some heterogeneous textures, such as disorder interlayer and stacking fault. It further proves the complexity of the crystal structure of the Ca RE fluorocarbonate minerals.

The Continuum Analytical Method of Steel Frame- Reinforced Concrete Shear Wall Mixed Structure

The inter-story drift stiffness considered the semirigidity of beam and column joints connection, and P-Delta second order effect of steel frame parts in the mixed structure is presented in the paper. After considering on the influence of semirigidity between steel beams and steel columns, second order effect of beam-column members for steel frame and structural second order effect, the traditional continuum analytial method used in RC shear-frames wall structure is developed to steel frames-reinforced concrete shear wall mixed structure subject to horizontal load in this paper. A continuum approach, which is suitable for analyzing steel frames-reinforced concrete shear wall mixed structure subject to horizontal load, is presented. The method is relatively simple and more practical. It will be referred to structural design for steel frames-reinforced concrete shear wall mixed structure.

Cycling performance of layered oxide cathode materials for sodium-ion batteries

Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.

Numerical simulations of compressible mixing layers with a discontinuous Galerkin method

Discontinuous Galerkin（DG） method is known to have several advantages for flow simulations,in particular,in fiexible accuracy management and adaptability to mesh refinement. In the present work,the DG method is developed for numerical simulations of both temporally and spatially developing mixing layers. For the temporally developing mixing layer,both the instantaneous fiow field and time evolution of momentum thickness agree very well with the previous results. Shocklets are observed at higher convective Mach numbers and the vortex paring manner is changed for high compressibility. For the spatially developing mixing layer,large-scale coherent structures and self-similar behavior for mean profiles are investigated. The instantaneous fiow field for a three-dimensional compressible mixing layer is also reported,which shows the development of largescale coherent structures in the streamwise direction. All numerical results suggest that the DG method is effective in performing accurate numerical simulations for compressible shear fiows.

Physico-Chemical Properties and Catalytic Behavior of LnSrNiO_4 Mixed Oxides for NO Decomposition

A series of LnSrNiO_4(A_2BO_4, Ln=La, Pr, Nd, Sm, Gd) mixed oxides with K_2NiF_4 structure, in which Asite(Sr) was partly substituted by individual light rare earth element, was prepared. The solid state physicochemical properties including crystal structure, defect structure, IR spectrum, valence state of Bsite ion, nonstoichiometric oxygen, oxygenous species, the properties of oxidation and reduction etc. as well as the catalytic behavior for NO decomposition on these mixed oxides were investigated. The results show that all of these mixed oxide catalysts have high activity for the direct decomposition of NO(at 900 ℃ the conversion of NO is more than 90%). The effect of the substitution of light rare earth elements at Asite on catalytic behavior for NO decomposition was elucidated.

Synthesis and Characterization of a Water-stable Metal-organic Framework Based on Mixed Ligands

A new water-stable metal-organic framework,[Cu_2（bdc）_2（tpt）_3]·2H_2O（1,H_2 bdc = terephthalic acid,tpt = 2,4,6-tri（4-pyridinyl）-1,3,5-triazine）,has been synthesized and characterized by elemental analysis,infrared（IR） spectrum,thermogravimetric analysis（TGA）,powder X-ray diffraction（PXRD） and single-crystal X-ray diffraction. Compund 1 crystalizes in monoclinic,space group C2/c with a = 30.147（5）,b = 11.0548（17）,c = 20.867（4） ？,β = 115.035（2）o,C_（70）H_（48）Cu_2N_（18）O_（10）,Mr = 1428.34,V = 6301.0（18） ？~3,Z = 8,D_c = 1.506 g/cm^3,μ = 0.754 mm^（–1）,F（000） = 2928,GOOF = 1.058,λ（MoK α） = 0.71073 ？,the final R = 0.0387 and wR = 0.1091 for 6230 observed reflections with I 〉 2σ（I）. In compound 1,the half metallacycles [Cu_2（tpt）_3] are linked by the bdc2-ligands to form a 1D bent ladder-like chain featured with a nano-sized channel,and these chains link each other via intermolecular hydrogen bonds and π-π stacking interactions to form a 3D supramolecular architecture with the voids filled with free water molecules. In addition,the water stability of 1 was investigated by PXRD patterns,which indicate that compound 1 keeps its structural integrity in boiling water for at least three days.

Effect of Substructure on Toughness of Lath Martensite/Bainite Mixed Structure in Low-Carbon Steels

The quantitative analysis of substructure in the martensite/bainite mixed structure, which is obtained from low-carbon NiCrMoV steels under different cooling conditions, was made by means of optical microscope （OM）, scanning electron microscope （SEM）, electron backscatter diffraction （EBSD）, and transmission electron microscope （TEM）, in order to research the effect on toughness. The test results indicate that the toughness of the steel is en- hanced with the decrease in the packet and block size under the condition of the same prior austenite grain size mixed with different ratios of martensite and bainite while the lath width is about 0.38μm. The calculation shows that both the packet and block boundaries have the same hindering effect on crack extension. Furthermore, the effect of the block width on impact energy is much larger than that of the packet. Therefore, the block can be used as microstruc- tural substructure to affect the toughness in low-carbon martensite steels, suggesting that the block size is ＂the effective grain size＂ for controlling toughness.

Al_(80)Ni_6Y_8Co_4Cu_2 GLASS ALLOYS CONTAINING NANOSCALEPARTICLES BY ISOTHERMAL ANNEALING OR QUENCHING

Al80Ni6 Y8 Co4 Cu2 amorphous ribbons were isothermally annealed and a mixed structure consisting of α-Al particle with a size of less than 15nm and Al3Ni compound with a size of about 30nm was obtained. The crystallization kinetics of Al80Ni6 Y8 Co4 Cu2 amorphous alloy shows that the precipitation of α-Al particles is the growth process controlled by diffusion of the solute elements rejected from the growing crystals. By quenching at different cooling rates, a mixed structure consisting of nanoscale α-Al particles and the remaining glass matrix or structure consisting of nanoscale particle (Al phase or Al3Ni compound) with a size of about 100nm was formed. The addition of Co elements and Cu elements to Al-Ni-Y alloy systems increases the glass formation ability of the alloy and the thermal stability of the supercooled liquid region against crystallization, which results from significant difference of atomic size, strong bonding nature among constituent elements and the low diffisivity of the solute elements due to the concentration gradient in the growing front of crystals.

Formation mechanism of basin-like depression defect in electric upsetting process of Ni80A superalloy

A kind of surface instability,basin-like depression defect companied by mixed grain structure at the bottom of large-scale valve during electric upsetting process,would significantly influence the microstructures and mechanical properties of components.In order to analyze the forming process of the basin-like depression defect,a finite element model for the electric upsetting process of Ni80A superalloy was developed using multi-field and multi-scale coupling analysis method.Subsequently,a series of parameters loading path schemes for force and current were designed by varying the initial value,peak value and value level,and their effects on basin-like depression and mixed grain structure were simulated and uncovered.It is concluded that the changes of heating speed and pressurization speed result in the different flow velocities between the inner and outer layers of billet,thus exerting the basin-like depression.Simulation results also indicate that these defects can be optimized through the parameter coordination between force and current.Finally,the validity and reliability of the finite element model were verified by physical experiments in electric upsetting process.

Effect of mixing structure on the hygroscopic behavior of ultrafine ammonium sulfate particles mixed with succinic acid and levoglucosan

Understanding the interactions between water and atmospheric aerosols is critical for estimating their impact on the radiation budget and cloud formation. The hygroscopic behavior of ultrafine （〈100nm） ammonium sulfate particles internally mixed with either succinic acid （slightly soluble） or levoglucosan （soluble） in different mixing structures （core-shell vs. well-mixed} were measured using a hygroscopicity tandem differential mobility analyzer （HTDMA）. During the hydration process （6-92% relative humidity （RH））, the size of core-shell particles （ammonium sulfate and succinic acid） remained unchanged until a slow increase in particle size occurred at 79Y~ RH; however, an abrupt increase in size （i.e., a clear deliquescence） was observed at ~72% RH for well-mixed particles with a similar volume fraction to the core-shell particles （80：20 by volume）. This increase might occur because the shell hindered the complete dissolution of the core-shell particles below 92% RH. The onset RH value was lower for the ammonium sulfate/levoglucosan core-shell particles than the ammonium sulfate/succinic acid core-shell particles due to levoglucosan＇s higher solubility relative to succinic acid. The growth factor （GF） of the core-shell particles was lower than that of the well-mixed particles, while the GF of the ammonium sulfate/levoglucosan particles was higher than that of ammonium sulfate/succinic acid particles with the same volume fractions. As the volume fraction of the organic species increased, the GF decreased. The data suggest that the mixing structure is also important when determining hygroscopic behavior of the mixed particles.

Residues of Logarithmic Differential Forms in Complex Analysis and Geometry

In the article, we discuss basic concepts of the residue theory of logarithmic and multi-logarithmic differential forms, and describe some aspects of the theory, de-veloped by the author in the past few years. In particular, we introduce the notion of logarithmic differential forms with the use of the classical de Rham lemma and give an explicit description of regular meromorphic differential forms in terms of residues of logarithmic or multi-logarithmic differential forms with respect to hypersurfaces, com-plete intersections or pure-dimensional Cohen-Macaulay spaces. Among other things, several useful applications are considered, which are related with the theory of holo-nomic D-modules, the theory of Hodge structures, the theory of residual currents and others.

Hydrothermal Synthesis and Characterization of a Novel Two-dimensional Framework Materials Constructed from Polyoxometalate and Coordination Groups: [H_2Mo_(5.5)V_(10.5)O_(40)(PO_4)][Cu(en)_2]_4·7H_2O

A novel compound [H_2Mo_ 5.5V_ 10.5O_ 40(PO_4)][Cu(en)_2]_4·7H_2O(1) was synthesized from V_2O_5, MoO_3, CuCl_2·2H_2O, en, H_3PO4 and H_2O in an aqueous solution via the hydrothermal method and characterized by means of single-crystal X-ray diffraction, elemental analyses, IR, EPR spectra and thermal analyses. C_ 16H_ 80Cu_4Mo_ 5.5N_ 16O_ 51PV_ 10.5 crystallized in a triclinic system, the space group is P1 with M=2660.63, a= 1.283590(10) nm, b=1.289910(10) nm, c=1.387870(10) nm, V=1.80942(2) nm 3, Z=2, D_x=4.883 g/cm 3, F(000)=2599, μ=6.956 mm -1, (Δ/σ)=0.000, S=1.089. The crystal structure was solved by the direct methods with the final R=0.0752 and wR=0.1988 for 6311 observed reflections with I≥2σ(I). The X-ray crystallography reveals that compound 1 is a novel two-dimensional framework material constructed from the mixed Mo/V polyoxometalate and coordination groups.

Members of University Digital Management Information System Design and Implementation Base on Three-Tier

In accordance with the organizational development process and management of party members, in this article it is based on the C/S and B/S mixed structure to finish the application design of client and servers, and using the language of VB.NET develop with Inner Mongolia Agricultural University, members of University College Digital Management Information System. The system from research projects of Agriculture University Occupation Technical College of Inner Mongolia.

Research on Energy Decision System based on Network Technology

This paper analyzes the C/S structure and B/S structure of their own characteristics, building energy decision support system based on network technology, elaborated Web GIS and database connections and other technical principles and applications. Mixed B/S structure mode development to achieve information management, energy consumption is forecast to show the query using the amomat of energy, energy supply and demand dynamic equilibrimn analysis and other functions, with simple, efficient, easy to operate and so on, and has good scalability and maintainability.

Kinematic analysis and simulation of a new-type robot with special structure

Common methods, such as Denavit-Hartenberg （D-H） method, cannot be simply used in kinematic analysis of special robots with hybrid hinge as it is difficult to obtain the main parameters of this method. Hence, a homogeneous transformation theory is presented to solve this problem. Firstly, the kinematics characteristic of this special structure is analyzed on the basis of the closed-chain theory. In such a theory, closed chains can be transformed to open chains, which makes it easier to analyze this structure. Thus, it will become much easier to establish kinematics equations and get the solutions. Then, the robot model can be built in the Simmechanics （a tool box of MATLAB） with these equation solutions. It is necessary to design a graphical user interface （GUI） for robot simulation. After that, the model robot and real robot will respectively move to some spatial points under the same circumstances. At last, all data of kinematic analysis will be verified based on comparison between data got from simulation and real robot.

The synthesis and structural studies of mixed ligand complex,tris(1-phenyl-3-methyl-4-trifluoroacetylpyrazol-5-one)mono(1-phenyl-3-methyl-pyrazol5-one)neodymium(Ⅲ)monohydrate

A mixed ligand neodymium complex containing 1-phenyl-3-methyl-4-trifluoroacetyl- pyrazol-5-one(HPMTFP)and 1-phenyl-3-methyl-pyrazol-5-one(PMP),with molecular formula Nd(PMTFP)_3·PMP·H_2O was synthesized.Its crystal and molecular structure has been determined by single crystal X-ray diffraction method.The complex crystallizes in monoclinic system with space group C_2~5h-P2_(1/n).There are four formula units in a cell of dimensions a=12.837(3),b=23.763(5),c=16.810(4) ,β=109.58(2)°.The structure has been refined by full-matrix least-squares techniques to a final R value of 0.0487 and Rw value of 0.432.The neodymium atom is coordinated to eight oxygen atoms with the average Nd-O bond length 2.439,Its thermostability,and mass spectrum have been discussed.

The role of environmental temperature on movement patterns of giant anteaters

Mammals can show conspicuous behavioral responses to thermal variation,including changes in movement patterns.We used an integrative approach to understand how environmental temperature can drive the movement behavior of a mammal with low capacity for physiological thermoregulation,the giant anteater(Myrmecophaga tridactyla).We tracked 52 giant anteaters in 7 areas throughout the Brazilian savannah.We estimated the distance moved,area used,use of forest areas,and mean environmental temperature for each monitoring day of each individual.We modeled these data with Mixed Structural Equations—considering the possible interactions between our variables and controlling for sex and body mass.Giant anteaters reduced displacement and increased forest use with decreasing environmental temperature,probably because of their low body heat production.It is possible that they reduce distance moved and area used by reducing the duration of activity.With decreasing temperature,forest habitats become warmer than open ones,besides buffer rain and chilly winds.Reducing displacement and using forests are important strategies to reduce body heat loss and the energetic costs of thermoregulation.However,decreasing movement can limit food access and,consequently,fitness.Therefore,we highlight the importance of forests as thermal shelters.With increasing frequency and intensity of extreme weather events,we showed the need to preserve forest patches to offer suitable conditions for tropical mammals’behavioral thermoregulation.In this context,policies favoring deforestation on Brazilian territory are especially worrisome.Finally,we emphasize the need of integrative approaches to understand the complex interactions between organisms and the environment.