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We construct a multiple-population discrete axisymmetric Jeans model for the Andromeda (M31) galaxy, considering three populations of kinematic tracers: 48 supergiants and 721 planetary nebulae (PNe) in the bulge and disk regions, 554 globular clusters extending to ∼30 kpc, and halo stars extending to ∼150 kpc of the galaxy. The three populations of tracers are organized in the same gravitational potential, while each population is allowed to have its own spatial distribution, rotation, and internal velocity anisotropy. The gravitational potential is a combination of stellar mass and a generalized NFW dark matter halo. We created two sets of models, one with a cusped dark matter halo and one with a cored dark matter halo. Both the cusped and cored model fit kinematics of all the three populations well, but the cored model is not preferred due to a too high concentration compared to that predicted from cosmological simulations. With a cusped dark matter halo, we obtained total stellar mass of 1.0 ± 0.1 × 1011 M ⊙, dark matter halo virial mass of M 200 = 7.0 ± 0.9 × 1011 M ⊙, virial radius of r 200 = 184 ± 4 kpc, and concentration of c = 20 ± 4. The mass of M31 we obtained is at the lower side of the allowed ranges in the literature and consistent with the previous results obtained from the H i rotation curve and PNe kinematics. Velocity dispersion profile of the outer stellar halo is important in constraining the total mass while it is still largely uncertain. Further proper motion of bright sources from Gaia or the Chinese Space Station Telescope might help on improving the data and lead to stronger constraints on the total mass of M31.

This study examined the phase-change Ge12Sb88 films that are fabricated through radio-frequency reactive magnetron sputtering to substrates with varying thermal conductivity. The in situ resistance was measured, and x-ray diffraction was conducted to investigate the phase-change behavior of the films under adjustments to the heating and annealing temperature. Differences in the films’ band gaps were determined by a spectrometer. The results were as follows: (a) the initial resistance levels of the films on low-thermal-conductivity substrates were higher than those on high-thermal-conductivity substrates. Resistance ratios were in the range of 102–103. The substantial changes in resistance influenced the characteristics of accelerating switching time and reduced the power consumption of the investigated materials. (b) Because of the partial crystallization of the films, an additional phase transition (from face-centered cubic (fcc)1 to fcc2) was observed among thin films on low-thermal-conductivity substrates. This phase transition can be leveraged in the development of data storage devices.

ReS2 is attracting much attention because of its stable trion state. This kind of stable trion state arises on account of weak interlayer coupling as well as anisotropic crystal structure. In this research, we have synthesized ReS2 flakes successfully by using chemical vapor deposition (CVD) method. Stable ionic states in hexagonal wafers are observed by photoluminescence spectroscopy (PL). This substance is stable at room temperature. The HRTEM image from the single ReS2 hexagon reveals that the individual hexagon is single crystal. EDS spectroscopy indicates the purity of the synthesized product. We find that the Re and S atoms ratio in pure ReS2 is 1:2. Then we fabricate a photo detector on individual ReS2 flakes and test its performance. We compare the photocurrent in dark current and under a 500 nm incident light for two media (air and 100 ppm H2). Emission current increases from 1.15 μA to 1.67 μA (forward) and from 7.9 μA to 13.8 μA (reverse). Therefore, the ReS2 hexagonal wafer is an ideal choice for stable and reliable room temperature optical gas sensor. And the material can also be used for fast switch.

Magnesium ion battery is one of the promising next-generation energy storage systems. Nevertheless, lack of appropriate cathode materials to ensure massive storage and efficient migration of Mg cations is a big obstacle for development of Mg-ion batteries. Herein, by means of first principles calculations, the geometric structure, electronic structure, Mg intercalation behavior and Mg diffusion behavior of the layered MoO2and two MoOSe (MoOSe(I) and MoOSe(V)) were systematically investigated. Layered MoO2shows semiconductor properties, while MoOSe displays metallic characteristics which ensure higher conductivity. The Mg cations tend to intercalate into octahedral sites for both MoO2and MoOSe. The maximum Mg-storage phases of the layered MoO2, MoOSe(I) and MoOSe(V) correspond to Mg0.666MoO2, Mg0.666MoOSe(I) and Mg0.666MoOSe(V), with theoretical specific capacities of 279, 191 and 191 mAh g-1, respectively. The calculated discharge plateaus of MoO2and two MoOSe are all about 1 V, which ensure that the layered MoO2and MoOSe electrodes can act as cathodes for Mg-ion batteries in the early stage. Moreover, comparing with other cathodes, the diffusion barrier of Mg cations and volume expansion during Mg intercalation process are competitive. The results suggest that layered MoO2and MoOSe are the promising cathode materials for Mg-ion batteries.

Three-dimensional (3D) core-shell structure of MnSn(OH)6 nanobox with MoS2 nanosheet is grown by series of simple steps for supercapacitor application. This core-shell is composited of MnSn(OH)6 nanobox as core and MoS2 nanosheet as shell. As-synthesized electrode material was characterized by Field emission scanning electron microscope (FESEM), energy dispersive spectroscopy (EDS) and transmission electron microscope (TEM). As-fabricated MnSn(OH)6@MoS2 electrode exhibited redox behavior with excellent specific capacitance of 1176 F g−1 at a current density of 4 A cm−2. These findings make MnSn(OH)6@MoS2 a better alternative source for energy storage devices.

We study the dynamical states of the 30 most massive galaxy clusters in the TNG100 simulation at redshift z = 0 using three types of tracers: stars, dark matter particles and satellite galaxies. If the massive galaxy cluster is spherically symmetric and relaxed, we can obtain the underlying total mass distribution accurately from its dynamical tracers using the spherical Jeans equations. Although the three tracers of clusters have very different number densities, velocity dispersions and anisotropies, they still trace the same total mass profile. We obtain the total mass profiles of clusters using these tracers separately and compare them with the true mass distributions. We find that: (1) the kinematics of dark matter trace the total mass of all clusters well and the mass inferred from dark matter are generally consistent with the true mass profiles with relative deviations smaller than ∼ 25% at all radii; (2) stars in ∼ 60% massive clusters are approaching equilibrium and the total mass of these clusters inferred from stars have relative deviations smaller than ∼ 50% at all radii. Stellar substructures are rich and the mass inferred from stars tend to be over-estimated in the inner region; and (3) satellite galaxies are unrelaxed in the inner region and become more relaxed as the radius increases. The total mass inferred from satellites are under-estimated in all regions.

In order to reduce the latch-up risk of the traditional low-voltage-triggered silicon controlled rectifier (LVTSCR), a novel LVTSCR with embedded clamping diode (DC-LVTSCR) is proposed and verified in a 0.18-μm CMOS process. By embedding a p+ implant region into the drain of NMOS in the traditional LVTSCR, a reversed Zener diode is formed by the p+ implant region and the n+ bridge, which helps to improve the holding voltage and decrease the snapback region. The physical mechanisms of the LVTSCR and DC-LVTSCR are investigated in detail by transmission line pulse (TLP) tests and TCAD simulations. The TLP test results show that, compared with the traditional LVTSCR, the DC-LVTSCR exhibits a higher holding voltage of 6.2 V due to the embedded clamping diode. By further optimizing a key parameter of the DC-LVTSCR, the holding voltage can be effectively increased to 8.7 V. Therefore, the DC-LVTSCR is a promising ESD protection device for circuits with the operation voltage of 5.5–7 V.

MgO-C refractories were prepared by using fused magnesia and flake graphite as main raw materials, adding metal aluminium powder as antioxidant, and using sucrose solution instead of phenolic resin as binder. The mechanical properties of MgO-C refractories obtained under different temperature conditions were studied and compared with those of phenolic resin bonded MgO-C refractories. The results show that CO2 and water vapor were mainly released from the solidified sucrose solution during the heating process, which can effectively solve the problem of harmful gases such as formaldehyde and phenol when the phenolic resin is heated. The MgO-C refractory material prepared by the sucrose solution as a binder has a good bonding strength after curing at 180 °C. The flexural strength and compressive strength of MgO-C refractories obtained by adding 6wt% sucrose solution are 4.90 MPa and 41 MPa. At high temperature, sucrose carbonization forms a strong carbon bonding, and the flexural strength of MgO-C refractories is 5.16 MPa and the compressive strength is 34 MPa, which is similar to the performance of the phenolic resin bonded MgO-C refractories.

In this study, novel MgO-C refractories using environmentally friendly sucrose as binder were prepared. To solve the harmful effects of formaldehyde and phenolic compounds that cause serious harm to the environment and human health released during the development, production and use of phenolic resin binders for MgO-C refractories, MgO-C refractories using environmentally friendly sucrose instead of phenolic resins as binders were prepared. The phase, microstructure, oxidation resistance and the antioxidant mechanism of MgO-C refractories prepared by adding sucrose as binder at different temperatures were analyzed. The formula between the weight loss of the material and the temperature is y=1.6225x+0.215 (600°C ∼ 1200°C). The addition of aluminium resulted in the formation of Al2O3 inside the refractories. Meanwhile, MgAl2O4 crystals were synthesized by Al2O3 and MgO at high temperature. The formation of Al2O3 and MgAl2O4 played an important role in improving the oxidation resistance property of MgO-C refractories using sucrose as binder.

The harmful components such as formaldehyde and phenolic compounds released during the development, production and use of MgO-C refractories prepared by using phenolic resin as a binder can cause serious harm to the environment and human health. In this paper, MgO-C refractory material with sucrose as binder and metal aluminium powder as antioxidant is prepared. Different slag temperature and time factors have a largely influence on the slag corrosion resistance of as-prepared samples. By analyzing the microstructure and composition of the samples, it is found that under the condition of constant time, the higher the temperature, the more obvious the slag corrosion phenomenon; under isothermal conditions, the longer the time, the more obvious the slag corrosion phenomenon. At the same time, it is revealed that the main corrosion process of MgO-C refractories prepared by adding sucrose as a binder is carbon oxidation and slag corrosion, which provides a theoretical basis for optimizing the slag resistance of MgO-C refractories.

It is of great significance to ensure the safe and reliable operation of the power grid by effectively evaluating the disaster risk of the power grid lines and arranging the sequence of line guard reasonably. A disaster risk assessment method of transmission lines based on TOPSIS is proposed in this paper where six typical natural disasters of the line are considered, the comprehensive risk values of different lines under different disasters combined with the hazards of line accidents is determined, the risk assessment of multiple transmission lines are realized, and its feasibility is verified by applying it to multiple transmission lines in a certain area of China Southern power grid.

Herein, we proffer a sensitive and selective sensor using ZnSe and ZnSe@ZnS quantum dots (QDs), for detection of toxic metal ions at nm level. It has been found that the TGA capped ZnSe and ZnSe@ZnS QDs were apparently sensitive to Pb2+ ions as perceptible from their fluorescence quenching measurements. However, in case of few common heavy metal ions such as Zn2+, Co2+, Fe2+, Mg2+, Cu2+, Ni2+ and Cd2+ ions, negligible quenching compared to Pb2+ ions was noted. Hence, we have successfully detected Pb2+ ions in aqueous solutions based on the photoluminescence (PL) spectroscopy. The observed linearity range was from 10 NM to 100 nM for both Pb2+ ions. An alternative QD based sensor for the spectroscopic detection, and concentration quantification of Pb2+ ions is proposed.

We report on the photovoltaic properties of La0.7Sr0.3MnO3/ZnO heterojunction fabricated by pulsed laser deposition methods. Nanosecond photovoltaic pulses are observed in this junction in the wavelength range from ultraviolet—visible to infrared. A qualitative explanation is presented, based on an analysis of the photovoltaic signals of p-n heterojunction.

The isotope shifts (ISs) for the 2s2S1/2 to 2p2P J (J = 1/2, 3/2) transitions of the lithium nuclei including the stable and short-lived isotopes are calculated based on the multi-configuration Dirac–Hartree–Fock method and the relativistic configuration interaction approach. The results are in good agreement with the previous theoretical and experimental results within a deviation less than 0.05%. The methods used here could be applied to the IS calculations for other heavier Li-like ions and few-electron systems.

The microwave absorbing properties of hollow carbon spheres modified by KOH were measured using a transmission/reflection coaxial method in the range of 2–18 GHz. The modification could result in a significant enhancement in the properties, including both the increment in absorbing intensity and bandwidth and the decrease in absorber thickness, which can be well explained by the high concentration of dangling bonds in per unit volume or per unit weight introduced during the modification. This dangling bond dominated mechanism could be used to instruct the design of absorbers with outstanding performances.

Based on the QMD model, in addition to the Skyrme-type, Yukawa and Coulomb interactions, a cluster's N, Z dependent macroscopic potential, which consists of the symmetrical energy of liquid drop model and shell, pairing correction energies, has been taken into account. It improved the structure of the clusters formed in heavy ion reactions at intermediate energy.

A Ho3+ and Pr3+ co-doped LiLuF4 single crystal was grown successfully by the Czochralski method. The polarized absorption spectra of the as-grown crystal have been investigated as a promising material for ~2.95 μm lasers. Based on the Judd–Ofelt theory, the spectral parameters of Ho3+ in the as-grown crystal were investigated in detail. Moreover, the emission probabilities and branching ratios for Ho3+ transitions from the excited state manifolds to the lower-lying manifolds were also calculated. The stimulated emission cross-sections of the 5I6 → 5I7 transition were calculated by using the Fuchtbauer–Ladenburg (FL) method. The fluorescence lifetime of the 5I6 and 5I7 manifold were measured with a value of 1.47 and 1.97 ms, respectively. It shows that Pr3+ ions depopulate the Ho3+: 5I7 level and have little influence on the Ho3+: 5I6 level at the same time, benefiting the possible population inversion for Ho3+: 5I6 → 5I7 transition.

Hollow carbon spheres (HCSs) and HCS/ZnO@C composite are synthesized by the reaction of zinc with sucrose and glycerol, respectively. The electromagnetic parameters of the HCSs and HCS/ZnO@C composite are measured by a coaxial line method. Both the real and imaginary complex permittivities and the loss tangent for the HCS/ZnO@C composite are larger than those for the HCSs. The electromagnetic absorption properties of the HCS/ZnO@C composite are advantageous over those of the HCSs, not only in band width but also in absorber thickness.

A double-surfactant-layer-assisted polymerization method was designed to prepare well-controlled core/shell metal oxide/polyaniline (c/s-MO/PANi) nanocomposites. Monodispersed and uniform core/shell nanocomposites including c/s-CuO/PANi, −Fe2O3/PANi, −In2O3/PANi and −Fe2O3/SiO2/PANi were successfully prepared using this polymerization method. By the removal of the cores for the resulting c/s-MO/PANi nanocomposites, hollow PANi capsules with different shapes and sizes were obtained. Our method provides a facile and effective way to design novel core/shell nanostructures with diverse functionality and high colloidal stability.

YVO4 nanocrystals doped with 10.0 mol% Eu3+ have been synthesized from an aqueous solution of (Y,Eu)(NO3)3 and NH4VO3 with or without ultrasonic irradiation. The ultrasonic irradiation has a strong effect on the morphology of the YVO4:Eu particles. The spindle-like particles with an equatorial diameter of 90–150 nm and a length of 250–300 nm could be obtained with ultrasonic irradiation, whereas only nanoparticles were produced without ultrasonic irradiation. The photoluminescence intensity of YVO4:Eu of the spindle-like particles was largely improved compared with that of the nanoparticles. The possible formation mechanism of the spindle-like particles of YVO4:Eu with the application of ultrasonic irradiation was discussed in this paper.