Numerical Simulation Investigation on Split Sleeve Cold Expansion of Ti-Al Stacked Structure

Split sleeve cold expansion(SSCX)can efiectively enhance fatigue life of holes by improving the field of residual stress.Numerical simulations were conducted to investigate the parameter influence mechanism and obtain higher compressive residual stress(CRS).Expansion method,degree of cold expansion(DCE),friction coefficient between laminations and depth-diameter ratio were analyzed.For Ti-Al stacked joint holes,two expansion methods are proposed,namely aluminum alloy first followed titanium alloy(Al first)and titanium alloy first followed aluminum alloy(Ti first).The results show that expansion method and DCE have significant efiects on the field of circumferential residual stress,and the friction has a negligible influence.A higher value of CRS and a wider layer of plastic deformation are induced with Ti first.Optimal DCE of TiAl stacked structure is 5.2%-5.6%.As the depth-diameter ratio is in the range of 0.5-1.25,a positive linear correlation between the maximum compressive residual stress(CRS_(max))and depth-diameter ratio is shown.

Effect of long-period stacking ordered structure on very high cycle fatigue properties of Mg-Gd-Y-Zn-Zr alloys

Magnesium alloys with a long-period stacking ordered(LPSO)structure usually possess excellent static strength,but their fatigue behaviors are poorly understood.This work presents the effect of the LPSO structure on the crack behaviors of Mg alloys in a very high cycle fatigue(VHCF)regime.The LPSO lamellas lead to a facet-like cracking process along the basal planes at the crack initiation site and strongly prohibit the early crack propagation by deflecting the growth direction.The stress intensity factor at the periphery of the faceted area is much higher than the conventional LPSO-free Mg alloys,contributing higher fatigue crack propagation threshold of LPSO-containing Mg alloys.Microstructure observation at the facets reveals a layer of ultrafine grains at the fracture surface due to the cyclic contact of the crack surface,which supports the numerous cyclic pressing model describing the VHCF crack initiation behavior.

Neutronics analysis of a stacked structure for a subcritical system with LEU solution driven by a D-T neutron source for~(99)Mo production

The utilization of neutrons markedly affects the medical isotope yield of a subcritical system driven by an external D-T neutron source.The general methods to improve the utilization of neutrons include moderating multiplying,and reflecting neutrons,which ignores the use of neutrons that backscatter to the source direction.In this study,a stacked structure was formed by assembling the multiplier and the low-enriched uranium solution to enable the full use of neutrons that backscatter to the source direction and further improve the utilization of neutrons.A model based on SuperMC was used to evaluate the neutronics and safety behavior of the subcritical system,such as the neutron effective multiplication factor,neutron energy spectrum,medical isotope yield,and heat deposition.Based on the calculation results,when the intensity of the neutron source was 59×10^(13)n/s,the optimized design with a stacked structure could increase the yield of ^(99)Mo to182 Ci/day,which is approximately 16% higher than that obtained with a single-layer structure.The inlet H_(2)O coolant velocity of 1.0 m/s and initial temperature of 20℃ were also found to be sufficient to prevent boiling of the fuel solution.

Stacked Structure Improves Output Reproducibility of Rubber Force Sensor

The electricity-conducting rubber force sensor is an attractive candidate as a low-cost material for tactile sensors. This article shows the evidence that the output reproducibility is largely improved when two identical sheets of the sensors are stacked. The stacked structure may reduce accidental error that is a fatal obstacle in an accurate control system.

Layer stacked SiO_(x) microparticle with disconnected interstices enables stable interphase and particle integrity for lithium-ion batteries

Severe mechanical fractu re and unstable interphase,associated with the large volumetric expansion/contraction,significantly hinder the application of high-capacity SiO_(x)materials in lithium-ion batteries.Herein,we report the design and facile synthesis of a layer stacked SiO_(x)microparticle(LS-SiO_(x))material,which presents a stacking structure of SiO_(x)layers with abundant disconnected interstices.This LS-SiO_(x)microparticle can effectively accommodate the volume expansion,while ensuring negligible particle expansion.More importantly,the interstices within SiO_(x)microparticle are disconnected from each other,which efficiently prevent the electrolyte from infiltration into the interior,achieving stable electrode/-electrolyte interface.Accordingly,the LS-SiO_(x)material without any coating delivers ultrahigh average Coulombic efficiency,outstanding cycling stability,and full-cell applicability.Only 6 cycles can attain>99.92%Coulombic efficiency and the capacity retention at 0.05 A g^(-1)for 100 cycles exceeds99%.After 800 cycles at 1 A g^(-1),the thickness swelling of LS-SiO_(x)electrode is as low as 0.87%.Moreover,the full cell with pure LS-SiO_(x)anode exhibits capacity retention of 91.2%after 300 cycles at 0.2 C.This work provides a novel concept and effective approach to rationally design silicon-based and other electrode materials with huge volume variation for electrochemical energy storage applications.

Active straining engineering on self-assembled stacked Ni-based hybrid electrode for ultra-low overpotential

Generating sufficient strains on metal surfaces are highly challenging owing to that most metals can deform plastically to relax the strains on the surfaces.In this work,we developed a facile but highly efficient stacked deposition strategy to in situ activation and reconstruction of NiO/NiOOH on Ni matrix,following with the migration of Fe ions to NiOOH.The Fe sites on the Ni/NiO/NiOOH facilitate the formation of the stable*OH oxygenated intermediates,and the Ni matrix in the catalyst provides the catalyst excellent stability.The oxygen evolution reaction(OER)performance of the stacked NiFe-5 with compressive strain displays the strengthened binding to oxygenated intermediates and superior OER activity,the ultralow overpotentials of 162 versus reversible hydrogen electrode at 10 mA cm^(-2).On the other hand,the Ni-5 without the incorporation of Fe has shown an outstanding hydrogen evolution reaction(HER)activity,affording an overpotential of 47 mV at 10 mA cm^(-2).The NiFe-5‖Ni-5 enables the overall water splitting at a voltage of 1.508 V to achieve 20 mA cm^(-2) with remarkable durability.The stacked deposition strategy improves binding strength of Ni-based catalysts to oxygenated intermediates via generating compressive strain,causing high catalytic activities on OER and HER.

Formation of β' phase in LPSO structures in an Mg88Co5Y7 alloy

Formation of β’ phase in long-period stacking ordered(LPSO) structures in an Mg;Co;Y;(at.%) alloy after aging at 200 °C for 24 h or electron beam(EB) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM). β’ phase was precipitated only in the Mg matrix but not in LPSO structures after aging at 200 °C for 24 h. LPSO structure containing stacking defects transforms into the β’-long phase during EB irradiation, which plays a key role in accelerating solute atoms’ diffusion. New complex β’(LPSO) structures formed in the alloy after EB irradiation, such as β’(12 H) structure with an orthorhombic lattice(Mg;Y, Cmcm,a = 2 _(a0)= 0.642 nm, b=4√3_(a0), c = 6 _(c0)= 3.12 nm).

A Silver Complex of 6,7-Dicyanodipyridoquinoxaline:π-Stacking Interactions and Luminescence

The reaction of 6,7-dicyanodipyridoquinoxaline （DICNQ） with AgNO3 in a 1：1 molar ratio by solution method gave a new complex [Ag（DICNQ）2]NO3 1. Single-crystal X-ray diffraction analysis reveals that the complex crystallizes in the space group Ibca of orthorhombic system with eight formula units in a cell. Crystal data for 1： a = 15.7055（17）, b = 18.411（2）, c = 20.680（2）A, V = 5979.7（11）A3, Z = 8, C32Hl2AgN13O3, Mr = 734.42, Dc = 1.632 g/cm3, μ= 0.734 mm-1, F（000） = 2928, S = 1.023 and T= 293（2） K. The final R = 0.0659 and wR = 0.1927 for 2118 observed reflections with I 〉 2σ（I）, and R = 0.0801 and wR = 0.2196 for all data. The complex builds up a packing structure by π-π stacking interactions and shows a luminescent feature.

Crystal Structure of 2,6-Dihistidine Dimethyl Ester Pyridine Acylamine Monohydrate

The crystal structure of the title compound,C21H25N7O7,has been determined in the orthorhombic space group C222（1） with a=8.993（10）,b=12.149（14）,c=22.20（2）A and Z=4.There exist intramolecular C-H…O and N-H…N hydrogen bonds in the title crystal structure.The intermolecular N-H…N and C-H…O hydrogen bonds together with π-π stacking interactions（face-to-face） link the molecules into an infinite three-dimensional supramolecular network.

Ring Structures of Silicone Oligomers:a Density Functional Theory Study

Silicones can be cross-linked to materials with a wide variety of properties.In this work,the ringed oligomers of [SiO(OH)_2]nas well as the stacked structures of trimer and the linear strands of the dimer and trimer were investigated systematically at B3 LYP/6-311 + + G(d,p) level combined with the conductor-like screening model(CPCM).This theoretical model reveals that,(1) SiO(OH)_2 will condense to stable ringed structures with SiO tetrahedrons;(2) in the ringed octamer [SiO(OH)_2]8,the macrocycle begins to pucker drastically;(3) from the linear strands of SiO rings it can be seen that the longer the chain is,the greater the energies decrease;(4) in [SiO(OH)_2]n(n ≥5) and in the strands of ringed oligomers,the highest occupied molecular orbitals(HOMOs) are primarily the n orbitals of the lone-pair electrons of oxygen atoms,so there are no delocalized π bonds.

Effects of Particle Stacking Angle on Heat Transfer Characteristics of Particles Close to the Wall

The primary energy demand increases, but a large amount of waste heat resources were not effectively used. To explore the influence of particle stacking structure on waste heat recovery process, CFD method was used to simulate. An unsteady heat transfer model of two particles was established, effect of particle stacking angle on heat transfer characteristics of the particles close to the wall under different initial temperature conditions was studied. Results show that: higher initial temperature, resulting in increased heat transfer time, the larger particle stacking angle causes the shortening of heat transfer time. When initial temperature is 1073 K, the average wall heat flux shows a trend of rapid decline first and then a slow one. At the same moment, the larger stacking angle causes smaller particle average temperature. The change of particle stacking angle shows a greater impact on the temperature of the particles close to adiabatic wall. The increase in the stacking angle resulting in better heat transfer characteristics between particles.

Synthesis and Crystal Structure of 4-(4,6-Dimethoxylpyrimidin-2-yl)-3-thiourea Carboxylic Acid Ethyl Ester

4-（4,6-Dimethoxyl-pyrimidin-2-yl）-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at room temperature. The crystal structure was determined by X-ray diffraction analysis. Crystallographic data： C10H14N4O4S, M, = 286.31, monoclinic, space group C2/c with a = 2.5309（3）, b = 0.67682（6）, c = 1.74237（19） nm, β = 114.744（3）°, V= 2.7106（5） nm3, Dc = 1.403 g/cm3, p = 0.225 mm-1, F（000） = 1200, Z= 8, R= 0.0514 and wR= 0.1529.

Crystal Structure of the Coordination Polymer of Sodium with Hydrazone Derivant of Acetoacetanilide

One new polymer, [Na（NPHSNPAB）（CH3OH）]n, where NPHSNPAB stands for Nphenyl-2-[2-hydroxy-3-sulfo-5-nitrophenylhydrazone]butadione-1,3, has been synthesized and characterized by ^1H NMR and FTIR spectroscopy and single-crystal X-ray diffraction. For this complex： C（17）H（17）N4NaO9S, Mr = 476.39, triclinic system, space group P1, a = 8.8741（18）, b = 10.942（2）, c = 12.039（2） A, α = 65.74（3）, β = 77.49（3）, γ = 84.30（3）o, V = 1040.3（4） A3, Z = 2, Dc = 1.521 g/cm^3, λ = 0.71073 A, F（000） = 492, S = 1.106, R = 0.0614 and w R = 0.1423 for 2945 observed reflections with I 〉 2（I）. X-ray structural analysis revealed that the structure of NPHSNPAB framework was almost planar by C–H···O, N–H···O, O–H···O, and O–H···S hydrogen bonds. Moreover, sodium（I） center was bound by six O and one N atoms, forming the coordination polymer. The molecular packing diagram showed complicated hydrogen bonds and π···π stacking interaction in the polymer. The average bond distance of the two dicyclic units（3.768 A） indicated strong π···π stacking interaction. The complex displays greenyellow emission at room temperature.

Stacking MoS_(2) flower-like microspheres on pomelo peels-derived porous carbon nanosheets for high-efficient X-band electromagnetic wave absorption

The key to solve increasingly severe electromagnetic(EM)pollution is to explore sustainable,easily prepared,and cost-effective EM wave absorption materials with exceptional absorption capability.Herein,instead of anchoring on carbon materials in single layer,MoS_(2) flower-like microspheres were stacked on the surface of pomelo peels-derived porous carbon nanosheets(C)to fabricate MoS_(2)@C nanocomposites by a facile solvothermal process.EM wave absorption performances of MoS_(2)@C nanocomposites in X-band were systematically investigated,indicating the minimum reflection loss(RLmin)of-62.3 dB(thickness of 2.88 mm)and effective absorption bandwidth(EAB)almost covering the whole X-band(thickness of 2.63 mm)with the filler loading of only 20 wt.%.Superior EM wave absorption performances of MoS_(2)@C nanocomposites could be attributed to the excellent impedance matching characteristic and dielectric loss capacity(conduction loss and polarization loss).This study revealed that the as-prepared MoS_(2)@C nanocomposites would be a novel prospective candidate for the sustainable EM absorbents with superior EM wave absorption performances.

Guinier-Preston Zone,Quasicrystal and Long-period Stacking Ordered Structure in Mg-based Alloys,A Review

Both the solid solution and precipitation are mainly strengthening mechanism for the magnesium-based alloys. A great number of alloying elements can be dissolved into the Mg matrix to form the solutes and precipitates.Moreover, the type of precipitates varies with different alloying elements and heat treatments, which makes it quite difficult to understand the formation mechanism of the precipitates in Mg-based alloys in depth. Thus, it is very hard to give a systematical regularity in precipitation process for the Mg-based alloys. This review is mainly focused on the formation and microstructural evolution of the precipitates, as a hot topic for the past few years, including Guinier-Preston Zones, quasicrystals and long-period stacking ordered phases formed in a number of Mg-TM-RE alloy systems, where TM = Al, Zn, Zr and RE = Y,Gd, Hd, Ce and La.

Friction and wear behavior of Mg–11Y–5Gd–2Zn–0.5Zr(wt%)alloy with oil lubricant

The sliding friction and wear behaviors of Mg-11Y-5Gd-2Zn-0.5Zr （wt%） alloy were investigated under oil lubricant condition by pin-on-disk configuration with a constant sliding distance of 1,000 m in the temperature range of 25-200℃. Results indicate that the volumetric wear rates and average friction coefficients decrease with the increase of sliding speeds, and increase with the increase of test temperature below 150℃. The hard and thermally stable Mg12（Y,Gd）Zn phase with long-period stacking order structure in the alloy presents significant wear resistance, The wear mechanism below 100℃ is abrasive wear as a result of plastic extrusion deformation. The corporate effects of severe abrasive, oxidative, and delaminating wear result in the tribological mechanism above 100℃.

Corrosion Behavior of Mg-Zn-Y Alloy with Long-period Stacking Ordered Structures

Mg-Zn-Y alloys with long-period stacking ordered structures were prepared by an ingot casting method. The corrosion performance of Mg-Zn-Y alloys was studied by combining gas-collecting test, immersion test and electrochemical measurements in order to determine the corrosion rate and mechanism of the alloys. The results showed that the volume fraction of Mg（12）YZn phase increased and the shape of the Mg（12）YZn phase changed from discontinuous to continuous net-like with increasing Zn and Y content. The corrosion rate of the alloys greatly depended on the distribution and volume fraction of the Mg（12）YZn phase. Corrosion products appeared at the junction of Mg phase and Mg（12）YZn phase, indicating that the Mg（12）YZn phase accelerated galvanic corrosion of Mg matrix. Mg（97）Zn1Y2 alloy shows the lowest corrosion rate due to the continuous distribution of Mg（12）YZn phase.

Domain wall state diagram for SrTiO_(3)/BaTiO_(3) superlattice structures

The domain wall structure of ferroelectric/paraelectric superlattices can be much more complex due to the influence of the superlattice stacking structure,the in-plane strain induced by the substrate and environmental temperature.In this study,we employed a phase field model to investigate the domain wall state of the SrTiO_(3)/BaTiO_(3) superlattice structure.The domain wall thickness for the SrTiO_(3)/BaTiO_(3) layer was measured using a hyperbolic function.Based on the simulation results,here,we show a domain wall state diagram to distinguish the hard and soft domain states.The polarization profiles across hard/soft domain walls were illustrated and analyzed.Our simulation results offer a useful concept for the control of the domain wall state in the ferroelectric superlattice.

Effects of Heat Treatments on Microstructures and Precipitation Behaviour of Mg_(94)Y_4Zn_2 Extruded Alloy

Microstructures and precipitation behaviours of Mg94Y4Zn2 （at. %） extruded alloy during solution treatment and ageing processes were investigated. Three major phases were observed in the as-cast Ug94Zn2Y4 alloy：α-Mg, block shaped 1 8R long period stacking ordered （LPSO） phase and Mg24Y5 cuboid particles. After homogenization and extrusion, the block shaped LPSO phase changed into plate-like shape aligned along the direction of extrusion. During solution treatment, a small fraction of LPSO phase was transformed from 18R structure to 14H type. The nano-scale β＇ phase with its close-packed planes being perpendicular to the direction of both α-Mg and LPSO structure was precipitated at ageing stage. The coexistence of β＇ and LPSO phase contributes to the strengthening of the alloy, with microhardness for the matrix and LPSO structures reaching 145.8 and 155,0 HV, respectively.

Characterization of microstructure in high strength Mg_(96)Y_3Zn_1 alloy processed by extrusion and equal channel angular pressing

The Mg96Y3Zn1 alloy processed by extrusion and equal channel angular pressing （ECAP） was investigated. It was found that the Mg96Y3Zn1 alloy processed by extrusion and ECAP obtained ultrafine grains and exhibited excellent mechanical properties. After ECAP, the average grain size of Mg96Y3Zn1 alloy was refined to about 400 nm. The highest strengths with yield strength of 381.45 MPa and ultimate tensile strength of 438.33 MPa were obtained after 2 passes at 623 K. The high strength of Mg96Y3Zn1 alloy was due to the strengthening by the grain refinement, the long period stacking （LPS） structure, solid solution, fine Mg24Y5 particles, and nano-scale precipitates. It was found that the elongation was decreased with pass number increasing. It was because that the cracks were preferentially initiated and propagated in the interior of X-phase during the tensile test.