Crystal structure,phase transitions,and thermodynamic properties of magnesium metavanadate(MgV_(2)O_(6))

As a promising anode material for magnesium ion rechargeable batteries,magnesium metavanadate(MgV_(2)O_(6))has attracted considerable research interest in recent years.A MgV_(2)O_(6)sample was synthesized via a facile solid-state reaction by multistep-firing stoichiometric mixtures of MgO and V2O5 powder under an air atmosphere.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)occurred at 841 K and the enthalpy change was 4.37±0.04 kJ/mol.The endothermic effect at 1014 K and the enthalpy change was 26.54±0.26 kJ/mol,which is related to the incongruent melting ofβ-MgV_(2)O_(6).In situ XRD was performed to investigate phase transition of the as-prepared MgV_(2)O_(6)at high temperatures.The cell parameters obtained by Rietveld refinement indicated that it crystallizes in a monoclinic system with the C2/m space group,and the lattice parameters of a=9.280 A°,b=3.501 A°,c=6.731 A°,β=111.76°.The solid-state phase transition fromα-MgV_(2)O_(6)toβ-MgV_(2)O_(6)was further studied by thermal kinetics,indicating that this process is controlled first by a fibril-like mechanism and then by a spherulitic-type mechanism with an increasing heating rate.Additionally,the enthalpy change of MgV_(2)O_(6)at high temperatures was measured utilizing the drop calorimetry,heat capacity was calculated and given as:Cp=208.3+0.03583T-4809000T^(−2)(298-923 K)(J mol^(−1)K^(−1)),the high-temperature heat capacity can be used to calculate Gibbs free energy of MgV_(2)O_(6)at high temperatures.

Existence of Monotone Positive Solution for a Fourth-Order Three-Point BVP with Sign-Changing Green’s Function

This paper is concerned with the following fourth-order three-point boundary value problem , where , we discuss the existence of positive solutions to the above problem by applying to the fixed point theory in cones and iterative technique.

THREE-POINT TRANSITION FUNCTIONS FOR TWO-PARAMETER MARKOV CHAINS AND THEIR FOUR SYSTEMS OF PARTIAL DIFFERENTIAL EQUATIONS

Analytic properties of three-point transition functions for wide-past Markov chains with two parameters are investigated. The concept "Standardness" is introduced. For standard three-point transition functions, four systems of leftward, rightward, downward and upward partial differential equations are derived.

Productive functional evolution of rural settlements:analysis of livelihood strategy and land use transition in eastern China

In China, rural settlements are usually multifunctional complex of natural societies and they also play important productive function. This study explored the spatiotemporal evolution of the productive function of three rural settlements, i.e.,Hetaoyuan, Dawengshan, and Gaoqiao, in the Yimeng Mountain in Shandong province of eastern China.Residents lived in this three types of rural settlements were all involved in agricultural production(i.e., grain threshing, drying and storage), which had remained dominant in Hetaoyuan. Dawengshan became an industrial-oriented settlement, while Gaoqiao became a commercial-oriented settlement. This evolution was reflected in the livelihood strategy changes of rural households and the transition of rural settlements changes. The choice of livelihood strategy was affected by the livelihood assets and policies, which resulted in the spatiotemporal evolution of the productive function of rural settlements. This study can provide references for the implementation and adjustment of rural residential land consolidation policies and the improvement of production and the quality of rural life in future.

Imaging the mantle transition zone beneath eastern and central China with CEArray receiver functions

We analyzed a total of 37 427 receiver-function data recorded by national and regional broadband seismic networks of the China Earthquake Administration to study the mantle transition zone beneath eastern and central China. Significant topography on both the 410-km and 660-km discontinuities was clearly imaged in the 3D volume of CCP （common-conversion-point） stacked images that cover an area of 102.5°F-122.5°E and 22.0°N-42.0°N. 3D crustal and mantle velocity models were used in computing the Ps time moveouts to better image the absolute depths of the two discontinuities. We found that the 660-km discontinuity is depressed up to 25 km along the east coast of China, indicating the presence of the subducted Pacific slab in the region. More interestingly, a double 660-km was observed beneath the Huanghai Sea, which was not seen from the 410-km discontinuity. We found a strong and localized anomaly beneath the Quaternary Datong volcano located at the northeastern edge of the Ordos Plateau in North China. The 410-km is depressed by as much as 15 km beneath the volcano. If the amount of the depression is caused by unmodeled low velocity anomaly in the upper mantle, it requires either a strong （4%-8%） localized low velocity anomaly near the lithosphere-asthenosphere boundary or -1.5% low velocity column across the entire upper mantle above the 410-km. The latter could suggest a deep origin of the Datong volcano, although it was usually attributed to edge-driven convection by most of the literatures.

Investigations of phase transition, elastic and thermodynamic properties of GaP by using the density functional theory

The phase transition of gallium phosphide （GAP） from zinc-blende （ZB） to a rocksalt （RS） structure is investigated by the plane-wave pseudopotential density functional theory （DFT）. Lattice constant a0, elastic constants cij, bulk modulus B0 and the pressure derivative of bulk modulus B0 are calculated. The results are in good agreement with numerous experimental and theoretical data. From the usual condition of equal enthalpies, the phase transition from the ZB to the RS structure occurs at 21.9 GPa, which is close to the experimental value of 22.0 GPa. The elastic properties of GaP with the ZB structure in a pressure range from 0 GPa to 21.9 GPa and those of the RS structure in a pressure range of pressures from 21.9 GPa to 40 GPa are obtained. According to the quasi-harmonic Debye model, in which the phononic effects are considered, the normalized volume V/Vo, the Debye temperature 8, the heat capacity Cv and the thermal expansion coefficient a are also discussed in a pressure range from 0 CPa to 40 GPa and a temperature range from 0 K to 1500 K.

Influence of Different Transition Modes on the Performances of a Hydraulic Turbine

In order to analyze the response of a hydraulic turbine to a variation in the operating conditions,different laws of variation in time of the massflow rate have been considered.After validating the overall numerical framework through comparison with relevant experiments,the performances of the considered turbine have been analyzed from afluid-dynamic point of view.The results show that different time profiles of the massflow rate(in this work,for simplicity,referred to as“transition functions”)have a varying influence on the transient behavior of the turbine.When a quadratic function is considered for the case of largeflow,the transient head and torque increase gradually with time,thefluctuation amplitude of the transient hydraulic efficiency at the main frequency is the largest,and thefluctuation amplitude of the radial force is the smallest.For the smallflow case,the time profile with exponential nature leads to the best results.The transient head and torque decrease gradually with time,the pulsation amplitude of the transient hydraulic efficiency is the largest at the main frequency,and the pulsation amplitude of the radial force is the smallest.

THE ANALYTICAL PROPERTIES FOR HOMOGENEOUS RANDOM TRANSITION FUNCTIONS

The concepts of Markov process in random environment and homogeneous random transition functions are introduced. The necessary and sufficient conditions for homogeneous random transition function are given. The main results in this article are the analytical properties, such as continuity, differentiability, random Kolmogorov backward equation and random Kolmogorov forward equation of homogeneous random transition functions.

Density functional calculations on the geometric structure and properties of the 3d transition metal atom doped endohedral fullerene M@C_(20)F_(20)(M=Sc-Ni)

This paper uses the generalised gradient approximation based on density functional theory to analyse the geometric structure and properties of the 3d transition metal atom doped endohedral fullerene M@C20F20 （M = Sc-Ni）. The geometric optimization shows that the cage centre is the most stable position for M, forming the structure named as M@C20F20-4. The inclusion energy, zero-point energy, and energy gap calculations tell us that Ni@C20F20-4 should be thermodynamically and kinetically stablest. M@C20F20-4 （M = Sc-Co） possesses high magnetic moments varied from 1 to 6 μB, while Ni@C20F20-4 is nonmagnetic. The Ni-C bond in Ni@C20F20-4 contains both the covalent and ionic characters.

Function Analysis of Urban Rail Transit Smart Station

In order to make rail transit smart stations serve passengers better,the potential of smart stations should be optimized to reduce time cost,and relieve traffic congestion.In this paper,the construction of smart stations based on the management experience of a subway station and the benefits of smart stations were analyzed and discussed.The construction of smart stations,as well as the key technologies for the construction of smart stations,will aid in the automation and intelligent management of subway stations.

A Hybrid Level Set Optimization Design Method of Functionally Graded Cellular Structures Considering Connectivity

With the continuous advancement in topology optimization and additive manufacturing(AM)technology,the capability to fabricate functionally graded materials and intricate cellular structures with spatially varying microstructures has grown significantly.However,a critical challenge is encountered in the design of these structures–the absence of robust interface connections between adjacent microstructures,potentially resulting in diminished efficiency or macroscopic failure.A Hybrid Level Set Method(HLSM)is proposed,specifically designed to enhance connectivity among non-uniform microstructures,contributing to the design of functionally graded cellular structures.The HLSM introduces a pioneering algorithm for effectively blending heterogeneous microstructure interfaces.Initially,an interpolation algorithm is presented to construct transition microstructures seamlessly connected on both sides.Subsequently,the algorithm enables the morphing of non-uniform unit cells to seamlessly adapt to interconnected adjacent microstructures.The method,seamlessly integrated into a multi-scale topology optimization framework using the level set method,exhibits its efficacy through numerical examples,showcasing its prowess in optimizing 2D and 3D functionally graded materials(FGM)and multi-scale topology optimization.In essence,the pressing issue of interface connections in complex structure design is not only addressed but also a robust methodology is introduced,substantiated by numerical evidence,advancing optimization capabilities in the realm of functionally graded materials and cellular structures.

Profile function properties & optical transition formulae

Profile function properties with different variables are discussed, the formulae of stimulated absorption, spontaneous and stimulated emission, absorption and emission coefficients, and cross sections are deduced, and some confusing issues are clarified.

Density Functional Theory Study on the Adsorption of CN on Transition Metal M(100) (M = Ni, Pd, Pt, Cu, Ag and Au) Surfaces

The adsorption of cyanide on the top site of a series of transition metal M（100） （M = Cu, Ag, Au, Ni, Pd, Pt） surfaces via carbon and nitrogen atoms respectively, with the CN axis perpendicular to the surface, has been studied by means of density functional theory and cluster model. Geometry, adsorption energy and vibrational frequencies have been determined, and the present calculations show that the adsorption of CN through C-end on metal surface is more favorable than that via N-end for the same surface. The vibrational frequencies of CN for C-down configuration on surface are blue-shifted with respect to the free CN, which is contrary to the change of vibrational frequencies when CN is adsorbed by N-down structure. Furthermore, the charge transfer from surface to CN causes the increase of surface work function.

Functional transition:Inconsistently parallel to the increase in future liver remnant volume after preoperative portal vein embolization

BACKGROUND Preoperative portal vein embolization(PVE)is a widely used strategy to enable major hepatectomy in patients with insufficient liver remnant.PVE induces hypertrophy of the future liver remnant(FLR)and a shift of the functional reserve to the FLR.However,whether the increase of the FLR volume(FLRV)corresponds to the functional transition after PVE remains unclear.AIM To investigate the sequential relationship between the increase in FLRV and functional transition after preoperative PVE using 3-dimensional(3D)computed tomography(CT)and 99mTc-galactosyl-human serum albumin(99mTc-GSA)singlephoton emission computed tomography(SPECT)fusion images.METHODS Thirty-three patients who underwent major hepatectomy following PVE at the Department of Gastroenterological Surgery I,Hokkaido University Hospital between October 2013 and March 2018 were enrolled.Three-phase dynamic multidetector CT and 99mTc-GSA SPECT scintigraphy were performed at pre-PVE,and at 1 and 2 wk after PVE;3D 99mTc-GSA SPECT CT-fused images were constructed from the Digital Imaging and Communications in Medicine data using 3D image analysis system.Functional FLRV(FFLRV)was defined as the total liver volume×(FLR volume counts/total liver volume counts)on the 3D 99m Tc-GSA SPECT CT-fused images.The calculated FFLRV was compared with FLRV.RESULTS FFLRV increased by a significantly larger extent than FLRV at 1 and 2 wk after PVE(P<0.01).The increase in FFLRV and FLRV was 55.1%±41.6%and 26.7%±17.8%(P<0.001),respectively,at 1 wk after PVE,and 64.2%±33.3%and 36.8%±18.9%(P<0.001),respectively,at 2 wk after PVE.In 3 of the 33 patients,FFLRV levels decreased below FLRV at 2 wk.One of the three patients showed rapidly progressive fatty changes in FLR.The biopsy at 4 wk after PVE showed macroand micro-vesicular steatosis of more than 40%,which improved to 10%.Radical resection was performed at 13 wk after PVE.The patient recovered uneventfully without any symptoms of pos-toperative liver failure.CONCLUSION The functional transition lagged behind the increase in FLRV after PVE in some cases.Evaluating both volume and function is needed to determine the optimal timing of hepatectomy after PVE.

Second-Order Correlation Function for Asymmetric-to-Symmetric Transitions due to Spectrally Indistinguishable Biexciton Cascade Emission

We report the observed photon bunching statistics of biexciton cascade emission at zero time delay in single quantum dots by second-order correlation function g（2） （T） measurements under continuous wave excitation. It is found that the bunching phenomenon is independent of the biexciton binding energy when it varies from 0.59 meV to nearly zero. The photon bunching takes place when the exeiton photon is not spectrally distinguishable from the biexciton photon, and either of them can trigger the %tart＇ in a Hanbury-Brown and Twiss setup. However, if the exciton energy is spectrally distinguishable from the biexciton, the photon statistics will become asymmetric and a cross-bunching lineshape can be obtained. The theoretical calculations based on a model of three-level rate-equation analysis are consistent with the result of g（2）（τ） correlation function measurements.

Functional Integral Approach to Transition Temperature of a Homogeneous ImperfectBose Gas

A functional integral approach (FIA) is introduced to calculate the transition temperature of a uniform imperfect Bose gas. With this approach we find that the transition temperature is higher than that of the corresponding ideal gas. We obtain the expression of the transition temperature shift as △Tc/To = 2.492 (na3) 1/6, where n is the density of particle number and a is the scattering length. The result has never been reported in the literature.

Exfoliation,functionalization and antibacterial activity of transition metal dichalcogenides

Due to the growing resistance of available drugs to bacterial infection and the slow development of antibiotics,there is a continuous need to design and develop new antibacterial agents.The interest to develop transition metal dichalcogenides(TMDs)based antibacterial agents has significantly increased in recent years.This research interest is driven by their interesting properties such as metallic and semiconducting nature of different phases,electronic confinement,large surface to volume ratio,the possibility of surface functionalization,and their potential application as a material in biomedical sciences.Different synthetic strategies have been developed to synthesize monolayered TMDs and their functionalization with different bioactive molecules.Researchers have given a lot of effort to establish the structure-activity correlation between different TMDs and their antibacterial activity.Here,we have reviewed various exfoliation strategies for TMDs,different methods for their functionalization,and the antibacterial activity of different TMDs.

Targeting the mitochondrial permeability transition pore in traumatic central nervous system injury

The mitochondrion serves many functions in the central nervous system （CNS） and other organs beyond the well-recognized role of adenosine triphosphate （ATP） production. This includes calcium-dependent cell signaling, regulation of gene expression, synthesis and release of cytotoxic reactive oxygen species, and the release of cytochrome c and other apoptotic cell death factors. Traumatic injury to the CNS results in a rapid and, in some cases, sustained loss of mitochondrial function. One consequence of compromised mitochondrial function is induction of the mitochondrial permeability transition （mPT） state due to formation of the cyclosporine A sensitive permeability transition pore （mPTP）. In this mini-review, we summarize evidence supporting the involvement of the mPTP as a mediator of mitochondrial and cellular demise following CNS traumatic injury and discuss the beneficial effects and limitations of the current ex- perimental strategies targeting the mPTP.

Ab initio study on phase transition and magnetism of BiFeO_3 under pressure

In this paper the first-principles calculations within local spin density approximation （LSDA）＋U show that BiFeO3 experiences a mixed phase state with P4mm structure being the intermediate phase before the pressure of phase transition is reached. The critical pressure for the insulator-metal transition （IMT） is found to be about 50 GPa. A pressure induced crossover of high-spin states and low-spin states is observed close to the IMT pressure in R3c structure. The LSDA＋U calculations account well for the mechanism of the IMT and crossover of spin states predicted in recent experiment （Ref.[1]）.

Theoretical Study on the Transition State of N-nitropyrazoles Rearrangement Reaction

Theoretical studies on the rearrangement reactions of nitropyrazoles have beeninvestigated. In order to gain a better understanding of the intermediate process of rearrangementreactions, the transition states of the rearrangement reactions were obtained by TS method at theB3LYP/6-311G（d, p） level of theory. The natural bond orbital charge, electrostatic potential andfrontier molecular orbital of the molecules in the process of rearrangement were analyzed, and thesolvent effect was also discussed. The rearrangement of nitropyrazoles involves two transitionstates and one intermediate, and the nitro group and hydrogen atom are two transfer groups forrearrangement reactions. The migration of these two groups leads to the change of chargedistribution and molecular structure. The structural changes of the molecules in different solventsare not significant, but the dipole moment of the molecule has obvious change.