Wind tunnel simulation of wind loading on a solid structure of revolution

The wind tunnel simulations of wind loading on a solid structure of revolution with one smooth and five rough surfaces were conducted using wind tunnel tests. Timemean and fluctuating pressure distributions on the surface were obtained, and the relationships between the roughness Reynolds number and pressure distributions were analyzed and discussed. The results show that increasing the surface roughness can significantly affect the pressure distribution, and the roughness Reynolds numbers play an important role in the change of flow patterns. The three flow patterns of subcritical, critical and supercritical flows can be classified based on the changing patterns of both the mean and the fluctuating pressure distributions. The present study suggests that the wind tunnel results obtained in the supercritical pattern reflect more closely those of full-scale solid structure of revolution at the designed wind speed.

Theoretical study on electronic structure and thermoelectric properties of PbS_xTe_(1-x)(x = 0.25, 0.5, and 0.75) solid solution

The electronic structure and thermoelectric（TE） properties of PbS_xTe_（1-x）（x = 0.25, 0.5, and 0.75） solid solution have been studied by combining the first-principles calculations and semi-classical Boltzmann theory. The special quasirandom structure（SQS） method is used to model the solid solutions of PbS_xTe_（1-x）, which can produce reasonable electronic structures with respect to experimental results. The maximum zT value can reach 1.67 for p-type PbS0.75Te0.25 and 1.30 for PbS0.5Te0.5 at 800 K, respectively. The performance of p-type PbS_xTe_（1-x） is superior to the n-type ones, mainly attributed to the higher effective mass of the carriers. The z T values for PbS_xTe_（1-x） solid solutions are higher than that of pure Pb Te and Pb S, in which the combination of low thermal conductivity and high power factor play important roles.

STUDIES ON SOLID STATE REACTIONS OF COORDINATION COMPOUNDS(LXⅡ)Solid state synthesis and crystal structure of the complex ICu_(0.84)Au_(0.16)(PPh_3)_2(SC(Ph)NHPh)CIJ·0.5CS_2

[Cu_(0.84)Au_(0.16)(PPh_3)_2(SC(Ph)NHPh)Cl]·0.5CS_2=,Mr=895.79,monoclinic,space group P2_1/a,a=17.231(3),b=14.611(2),c=18.000(3) ,β=105.56(2)°,V=4365(1) ~3, Z=4,D_c=1.37g/cm^3.,λ(MoK_α)=0.71073 ,μ=12.15cm^(-1),F(000)=1855,R=0.052, R_W=0.045 for 3930 observed reflections with Ⅰ>1.5σ(Ⅰ).The central metal atom has a dis. torted tetrahedral geometry with bond lengths Cu-S=2.384(2) (Au-S=2.389(4)), Cu-Cl=2.481(3)(Au-Cl=2.474(1))and Cu-P=2.269(2)-2.289(2)(Au-P=2.270(4)-2.279(4)) .

Perovskite Sr0.9Fe0.9Zr0.1O3-δ:Redox-stable Structure,Oxygen Vacancy,Electrical Properties and Steam Electrolysis Performance

Many researchers have studied on perovskite oxide for its unique structure.Perovskite oxides,ABO3-δ,with different A and B metals have shown wide applications in many fields,in particular solid oxide electrolysers.SrFeO3-δ,typical perovskite oxides,in which iron is the mixed-valence cation with the capacity to change the chemical valence,have a wide range of oxygen nonstoichiometry.In this study,Sr（0.9）Fe（0.9）Zr（0.1）O3-δ（SFZO） is synthesized and then treated in 5%H2/Ar and air at high temperature,exhibiting excellent redox stability.Redox-stable structure,oxygen vacancy and electrical properties of SFZO are investigated.Steam electrolysis is then performed with SFZO cathode under 5%H2O/5%H2/Ar and 5%H2O/Ar atmospheres,respectively.The present results indicate that the SFZO is a novel promising cathode material for solid oxide steam electrolyser.

Synthesis and Crystal Structure of Sm Cu_(7.73)In_(3.27): a New 3D Framework Based on [Cu_5In_4M_4](M=Cu/In) Cluster

A new intermetallic compound, SmCuT.vslns.27, has been synthesized by solid-state reaction of the corresponding pure elements at high temperature, and structurally characterized by single-crystal X-ray diffraction study. SmCu7.731n3.27 crystallizes in tetragonal space group P4/mbm with a = 8.6213（4）, c = 10.2538（9）, V= 762.13（8） A3, Z = 4, M,. = 1018.90, Dc= 8.880 g/cm3,μ = 38.244 mm-1, F（000） = 1789, and the final R = 0.0374 and wR = 0.0836 for 514 observed reflections with I 〉 2σ（I）. The structure of SmCu7.69In3.31 belongs to a new structure type and features a three-dimensional （3D） [Cusln2M4] （M = Cu/In） framework composed of [CusinnM4] clusters interconnected via sharing In atoms as well as Cu-ln and In-In bonds. The Sm atoms are located in the one-dimensional （1 D） tunnels along the c-axis. The structural relationship of the title compound with other similar Sm-Cu-In phases was also studied. Band structure calculations based on Density Functional Theory （DFT） method indicate that SmCuT.69In3.31 is metallic.

Ensuring the possibility of using thorium as a fuel in a pressurized water reactor(PWR)

The possibility of utilizing thorium as a fuel in a pressurized water reactor(PWR)has been proven from the neutronic perspective in our previously published work without assessing the thermal hydraulic(TH)and solid structure performances.Therefore,the TH and solid structure performances must be studied to confirm these results and ensure the possibility of using a thorium-based fuel as an excellent accident-tolerant fuel.The TH and solid structure performances of thorium-based fuels were investigated and compared with those of UO_(2).The radial and axial power peaking factors(PPFs)for UO_(2),(^(232)Th,^(235)U)O_(2),and(^(232)Th,^(233)U)O_(2)were examined with a PWR assembly to determine the total PPF of each one.Both Gd_(2)O_(3)and Er_(2)O_(3)were tested as burnable absorbers(BAs)to manage the excess reactivity at the beginning of the fuel cycle(BOC)and reduce the total PPF.Er_(2)O_(3)resulted in a more significant reduction to the total PPF and,therefore,a greater reduction to the temperature distribution compared to Gd_(2)O_(3).Given these results,we analyzed the effects of adding Er_(2)O_(3)to thorium-based fuels on their TH and solid structure performances.

Physical Properties of Ⅲ-Antiminodes—a First Principles Study

A comprehensive first principles study of III-Antimonide binary compounds is hardly found in literature. We report a broad study of structural and electronic properties of boron antimonide （BSb）, aluminium antimonide （AlSb）, gallium antimonide （GaSb） and indium antimonide （InSb） in zineblende phase based on density functional theory （DFT）. Our calculations are based on Full-PotentiM Lineaxized Augmented Plane wave plus local orbitals （FP- L（APWq-lo）） method. Different forms of exchange-correlation energy functional and corresponding potential are employed for structural and electronic properties. Our computed results for lattice parameters, bulk moduli, their pressure derivatives, and cohesive energy are consistent with the available experimental data. Boron antimonide is found to be the hardest compound of this group. For band structure calculations, in addition to LDA and GGA, we used GGA-EV, an approximation employed by Engel and Vosko. The band gap results with GGA-EV are of significant improvement over the earlier work.

Nature of the band gap of halide perovskites ABX_3(A=CH_3NH_3,Cs;B=Sn,Pb;X=Cl,Br,I):First-principles calculations

The electronic structures of cubic structure of ABX3（A=CH3NH3, Cs; B=Sn, Pb; X=Cl, Br, I） are analyzed by den- sity functional theory using the Perdew-Burke-Ernzerhof exchange-correlation functional and using the Heyd-Scuseria- Ernzerhof hybrid functional. The valence band maximum （VBM） is found to be made up by an antibonding hybridization of B s and X p states, whereas bands made up by the π antibonding of B p and X p states dominates the conduction band minimum （CBM）. The changes of VBM, CBM, and band gap with ion B and X are then systematically summarized. The natural band offsets of ABX3 are partly given. We also found for all the ABX3 perovskite materials in this study, the bandgap increases with an increasing lattice parameter. This phenomenon has good consistency with the experimental results.

First-principles study of the (001) surface of cubic PbHfO_3 and BaHfO_3

Using first-principles techniques, we investigate the （001） surfaces of cubic PbHfO3 （PHO） and BaHfO3 （BHO） terminated with both AO （A=Pb and Ba） and HfO2. Surface structure, partial density of states, band structure, and surface energy are obtained. The BaO surface is found to be similar to its counterpart in BHO. For the HfO2-terminated surface of cubic PHO, the largest relaxation appears on the second-layer atoms but not on the first-layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the （001） surface for PHO is stronger than that for BHO. The surface thermodynamic stability is explored, and it is found that both the PbO- and the BaO-terminated surfaces are more stable than the HfO2-terminated surfaces for PHO and BHO, respectively. The surface energy calculations show that the （001） surface of PHO is more easily constructed than that of BHO.

First-principles calculations of structural and electronic properties of Tl_xGa_(1-x)As alloys

The zincblende ternary alloys Tl_xGa_（1-x） As（0 〈 x 〈 1） are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation. To model the alloys,16-atom supercells with the 2 × 2 × 2 dimensions are used and the dependency of the lattice parameter, bulk modulus,electronic structure, energy band gap, and optical bowing on the concentration x are analyzed. The results indicate that the ternary Tl_xGa_（1-x） As alloys have an average band gap bowing parameter of 4.48 eV for semiconductor alloys and 2.412 eV for semimetals. It is found that the band gap bowing strongly depends on composition and alloying a small Tl content with GaAs produces important modifications in the band structures of the alloys.

First-principles study of the co-effect of carbon doping and oxygen vacancies in ZnO photocatalyst

Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application,C-doping or oxygen vacancy(Vo)as a single defect in ZnO still has limitations for photocatalytic activity.Meanwhile,the influence of co-existence of various defects in ZnO still lacks sufficient studies.Therefore,we investigate the photocatalytic properties of ZnOx C0.0625(x=0.9375,0.875,0.8125),confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO.To clarify the underlying mechanism of co-existence of various defects in ZnO,we perform systematically the electronic properties calculations using density functional theory.It is found that the coeffect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO.Moreover,the impact of the effective masses of ZnO_(x)C_(0.0625)(x=0.9375,0.875,0.8125)is also taken into account.In comparison with heavy Vo concentrations,the light Vo concentration(x=0.875)as the optimal component together with C-doping in ZnO,can significantly improve the visible-light absorption and benefit photocatalytic activity.

Study of magnetic and optical properties of Zn1-xTMxTe(TM = Mn,Fe,Co,Ni) diluted magnetic semiconductors：First principle approach

We present structural,magnetic and optical characteristics of Zn_（1-x）TM_xTe（TM = Mn,Fe,Co,Ni and x = 6.25%）,calculated through Wien2 k code,by using full potential linearized augmented plane wave（FP-LAPW） technique.The optimization of the crystal structures have been done to compare the ferromagnetic（FM） and antiferromagnetic（AFM） ground state energies,to elucidate the ferromagnetic phase stability,which further has been verified through the formation and cohesive energies.Moreover,the estimated Curie temperatures T_c have demonstrated above room temperature ferromagnetism（RTFM） in Zn_（1-x）TM_xTe（TM =Mn,Fe,Co,Ni and x= 6.25%）.The calculated electronic properties have depicted that Mn- and Co-doped ZnTe behave as ferromagnetic semiconductors,while half-metallic ferromagnetic behaviors are observed in Fe- and Ni-doped ZnTe.The presence of ferromagnetism is also demonstrated to be due to both the p-d and s-d hybridizations between the host lattice cations and TM impurities.The calculated band gaps and static real dielectric constants have been observed to vary according to Penn＇s model.The evaluated band gaps lie in near visible and ultraviolet regions,which make these materials suitable for various important device applications in optoelectronic and spintronic.

Studies on solid state reactions of coordination compounds——XLⅦ.Solid state syntheses and crystal structures of cluster compounds {Cu_3MoS_3I}(PPh_3)_3S and {Cu_3WS_3Br} (PPh_3)_3S

Reactions of [NH_4]_2[MS_4](M=Mo,W),CuX(X=Br,I)and PPh_3 in the solid state produced four mixed-metal sulfur containing clusters{Cu_3MS_3X}(PPh_3)_3S(M=Mo,W;X=Br,I),two of which (1:M=Mo,X=I;2:M=W,X=Br)were structurally determined.Crystals of 1 and 2 are triclinic, space group P(1:a=11.895(3),b=13.107(1),c=20.473(2),α=74.95(6),β=84.87(8),γ=64.27(7)°, Z=2,V=2776.1 ,Rw=0.064 for 6443 observed reflections.2:α=11.876 (1),b=13.065 (2),c= 20.325(2),α=74.95(1),β=85.39(1),γ=64.09(1)°,Z=2,V=2737.3,R_w=0.055 for 5303 observed reflections).The results of the structure determination showed that the central units of the two cubane- like cluster compounds are composed of four metal atoms and four non-metal atoms situated at alter- nate comers.The differences of cubane-like cluster compounds obtained from solid state reactions and from solution reactions are discussed.

Solids behavior in dilute zone of a CFB riser under turbulent conditions

The behavior of the solid phase in the upper zone of a circulating fluidized bed riser was studied using a phase Doppler anemometer. Glass particles of mean diameter 107μm and superficial gas velocities UE covering the turbulent and the beginning of the fast fluidization regime were investigated. Three static bed heights were tested. Ascending and descending particles were found co-existing under all oper ating conditions tested, and at all measurement locations. Superficial gas velocity proved/happened to have a larger effect on descending particles at the wall and on ascending particles in the central region. Transversal particle velocities in both directions （toward the center and toward the wall） behaved rela- tively equivalently, with only slight difference observed at the wall. However, observation of the number of particles moving in either transversal direction showed a change in bed structure when increasing Ug. Furthermore, a balance was constantly observed between the core zone and the annulus zone where the mutual mass transfer between these two zones occurred continuously. Transition from a slow to a fast particle motion was accompanied by a transition to high levels of velocity fluctuations, and was found corresponding to the appearance of significant solid particle flow rate.

A generalized mathematical model for non-catalytic gas-solid reactions

Based on a general classification and characteristic comparison of the existing models, a new model for non-catalytic gas-solid reactions is proposed and a general formulation for the model in terms of the solid conversion, X, is presented in mis paper. The model, referred to the generalized model, is demonstrated to be applicable to any solid reactant of general structure ranging from highly porous to nonporous materials. It is shown that the generalized model incorporates the grain and pore structure for a solid pellet and can be reduced to the grain and random pore models as extreme cases.

^(13)C NMR and structural study of solid state naphthol-1 and naphthol-2 arylazo-derivatives

Solid state ^(13)C NMR spectra of a series of naphthol-1 and naphthol-2-arylazo--deriva- tives were studied and compared with respective results in solutions.Signals of carbon nuclei of naphthalene ring were assigned.Tautomeric forms of compounds were determined.It was shown that 4-(p-NO_2C_6H_4)-azonaphthol-1 and 1-(p-NO_2C_6H_4)-azonaphthol-2 in solid state existed ex- clusively in quinohydrazone form.The other two compounds——1-(C_6F_5)-azonaphthol-2 and 2-(p- CH_3C_6H_4)-azonaphthol-1 in solid state were not found in the form of individual tautomeric mixtures but in respective tautomeric equilibrium form.Thus,during transition from liquid to solid state, the tautomeric equilibrium was practically unchanged.In solid state it was found that rotation around aryl-N bond was hindered in the time scale of NMR spectroscopy.

Microscopic and spectroscopic analysis of atmospheric iron-containing single particles in Lhasa,Tibet

The Tibetan Plateau,known as the“Third Pole”,is currently in a state of perturbation caused by intensified human activity.In this study,56 samples were obtained at the five sampling sites in typical area of Lhasa city and their physical and chemical properties were investigated by TEM/EDS,STXM,and NEXAFS spectroscopy.After careful examination of 3387single particles,the results showed that Fe should be one of the most frequent metal elements.The Fe-containing single particles in irregular shape and micrometer size was about7.8%and might be mainly from local sources.Meanwhile,the Fe was located on the subsurface of single particles and might be existed in the form of iron oxide.Interestingly,the core-shell structure of iron-containing particles were about 38.8%and might be present as single-,dual-or triple-core shell structure and multi-core shell structure with the Fe/Si ratios of 17.5,10.5,2.9 and 1.2,respectively.Meanwhile,iron and manganese were found to coexist with identical distributions in the single particles,which might induce a synergistic effect between iron and manganese in catalytic oxidation.Finally,the solid spherical structure of Fe-containing particles without an external layer were about 53.4%.The elements of Fe and Mn were co-existed,and might be presented as iron oxide-manganese oxide-silica composite.Moreover,the ferrous and ferric forms of iron might be co-existed.Such information can be valuable in expanding our understanding of Fe-containing particles in the Tibetan Plateau atmosphere.

Unveiling anneal hardening in dilute Al-doped Al_(x)CoCrFeMnNi(x = 0,0.1) high-entropy alloys

Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.

Synthesis and thermal behavior of [Li(thf)3(μ-Cl)La{N(SiMe3)2}3] and its investigation as spin-coating precursor for lanthanum-based layer formation

The lanthanum（Ⅲ） complex [Li（thf）3（μ-CI）La{N（SiMe3）2}3]（3） was obtained by the reaction of LaCl3 with three equiv of Li[N（SiMe3）2]3 in a tetrahydrofuran solution. The molecular structure of 3 in the solid state was characterized by a tetracoordinated anionic lanthanide（Ⅲ） amide in form of an adduct with LiCl（thf）3 as evidenced by single crystal X-ray structure analysis. In order to study the suitability of 3 as a precursor for the deposition of La2O3/LiLaSiO4 by thin layer deposition techniques,its thermal behavior was investigated by thermogravimetry（TG） and TG-MS-coupled studies. TG studies show a two-step decomposition process, whereby volatile decomposition products can be detected during the second decomposition step. TG measurements under an atmosphere of oxygen produced La2O3, Calcination processes of 3 under ambient atmosphere for 10 h at 1000 ℃ gave La2O3 and LiLaSiO4,which was confirmed by PXRD studies. Metal-organic 3 was applied as spin-coating precursor for La2O3 thin film formation giving the as-deposited layers nearly crack-free.

Non-affinity:The emergence of networks from amorphous planar graphs

The primary research of physics is to reveal the underlying law of the physical world.However,for a complex system consisting of multiple components,even if we know every details of each component,we still cannot predict the collective behavior due to the emergence phenomenon.The amorphous networks of mass points hinged by springs belong to such a complex system.Owing to the non-affinity,one of the emergence phenomena of the network,the displacements field of the internal mass points under the external load tends to be chaotic,and there is no well-established theoretical framework to describe these points’collective behavior analytically.The non-affine mechanical responses of the amorphous networks are very common,whereas the affine response is rare and it occurs only in those lattices with one site per unit cell.The network’s non-affinity prevents us from further investigating the relationship between its intrinsic properties(such as the contact number,local structure,and topological characteristics)and the mechanical behaviors.As a result,it is very complicated and difficult to predict the responses of an amorphous network to an imposed strain.Interestingly,a sort of amorphous network derived from the jammed particles is reported to have almost perfect affine mechanical behavior,in a stark contrast with the general perception.These findings may shed light on uncovering the structural factors that affect the network’s affinity.This article will give a short review of the latest advances in this area.