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In this paper, the tension-tension fatigue behavior of unidirectional SiC/Si 3 N 4 ceramic-matrix composite with strong and weak interface bonding at room temperature has been investigated using a micromechanical approach. The hysteresis loops models considering different interface slip cases have been developed to establish the relationships between fatigue hysteresis loops, hysteresis dissipated energy, hysteresis modulus, and the interface shear stress. The damage evolution process under tension-tension fatigue loading has been analyzed using hysteresis loops. By comparing experimental fatigue hysteresis dissipated energy with theoretical computational values, the interface shear stresses of SiC/Si 3 N 4 composite with weak and strong interface bonding were obtained for different cycle numbers. The fatigue life S‒N curves and broken fibers fraction versus cycle number curves corresponding to different fatigue peak stresses have been predicted. For SiC/Si 3 N 4 with strong interface bonding, the fatigue limit stress approaches to 75% tensile strength, which is much higher than that of composite with weak interface bonding, i.e., 58% tensile strength, due to the higher interface shear stress degradation rate for weak bonding interface. [ABSTRACT FROM AUTHOR]

A novel gel polymer electrolyte (GPE) based on polyvinylidene fluoride (PVdF) and polyvinyl alcohol (PVA) with reliable electrochemical performance, mechanical robustness and safety features is prepared by a casting method. The physical, electrochemical and thermal properties of the casting membrane are characterized by scanning electron microscopy (SEM), atomic force microscope (AFM), thermal gravimetric analysis (TG), alternating-current (AC) impedance and charge–discharge techniques. The resulting polymer membrane shows a high ionic conductivity of 1.19 × 10 −3 S/cm with 45.5 wt% of ionic liquid (IL) content while the cell assembled with PVdF/PVA/IL electrolyte delivers better electrochemical stability and higher discharge capacity than that without IL, and the thermal stability is obtained compared to conventional liquid electrolytes. [ABSTRACT FROM AUTHOR]

The atomic structure of Si(110)/SiC(0001) heterojunctions prepared on 6H-SiC(0001) was characterized by transmission electron microscopy and X-ray diffraction. An FCC-on-HCP parallel epitaxy is achieved for the Si(110)/SiC(0001) heterostructure with a growth temperature of 1050 °C and the in-plane orientation relationship is Si[1-10]//6H-SiC[11-20]. The pure edge misfit dislocations with a Burgers vector of 1 3 <11-20> SiC parallel to the interface are observed to accommodate the extreme lattice mismatch. Along the in-plane orientation Si[1-10]SiC[11-20], the Si/6H-SiC interface has a 4:5 Si-to-SiC matching mode with a residual lattice-mismatch of 0.26%. The misfit dislocation density at the Si/SiC interface is calculated as 1.217×10 14 cm −2 . [ABSTRACT FROM AUTHOR]

In this study, we prepared a kind of composite solid polymer electrolyte (CSPE) based on montmorillonite (MMT) nano-clay fillers, lithium-bis(trifluoromethanelsulfonyl) (LiTFSI), polyvinylidenedifluoride (PVDF) and polyvinyl alcohol (PVA) copolymer by the casting method. Effect of the montmorillonite on ionic conductivity and electrochemical properties of the polymer electrolyte was demonstrated. The result CSPE obtained a higher ionic conductivity up to 4.31 × 10 −4 S cm −1 at room temperature when 4.0 wt% MMT was contained, and the maximum lithium ions transference number of 0.40 was achieved. Electrochemical performance of the polymer solid electrolyte was evaluated in Li/polymer electrolyte/LiFePO 4 coin cell. Good performance with low capacity fading on charge–discharge cycling was achieved, indicating the potential application of the as-prepared CSPE in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Si films with <111> preferred orientation have been prepared on 6H–SiC(000−1) C-face. HRTEM and SAED results indicate that the Si film has epitaxial connection with the 6H–SiC substrate and the parallel-plane relationship of the Si/6H–SiC heterostructure is (111)Si//(000−1)6H–SiC. Using fast Fourier transform and Fourier mask filtering technique, misfit dislocations are clearly observed at the Si/6H–SiC interface, which accommodate the most of lattice mismatch strain. Every four Si (111) lattice planes are registered with five 6H–SiC(000−1) lattice planes along the interface. Based on the 4:5 lattice matching mode, the lattice structure of the Si/6H–SiC interface and its stability were energetically investigated by molecular dynamics simulations. When the Si films grow preferentially along <111> orientation on 6H–SiC(000−1) C-face, the misfit strain in Si layer significantly reduces due to the relaxation of C atoms in SiC layer near the Si/6H–SiC interface, and thus the Si/6H–SiC heterostructure has a stable interface with a small interface formation energy of −14.24eV. [Copyright &y& Elsevier]

The Karhunen–Loève (K–L) expansion has been successfully applied to the simulation of highly skewed non-Gaussian processes based on the prescribed covariance and marginal distribution functions. When the stationary random process is indexed over a domain that is much larger than the correlation distance, the K–L expansion will approach the spectral representation. The non-Gaussian K–L technique is applied in the popular spectral representation as a special case to facilitate comparison with translation-based spectral representation. Processes with both incompatible and compatible spectral density and marginal distribution functions are simulated numerically. It is demonstrated that K–L expansion can be used to address the situation with incompatible target functions where the commonly used translation approach may not be applicable. It is therefore a more robust method for simulation of non-Gaussian processes because it can generate different processes satisfying the same target spectral density function and the same target marginal distribution function regardless of their compatibility. [Copyright &y& Elsevier]

Abstract: The aim of this work is improving the surface characteristics of aluminum matrix composites reinforced with 70vol.% SiC particles (SiCp/Al) used in relation to electroless Ni–P plating process in alkaline bath. Special pretreatment methods are necessary to obtain the films which have tight adhesion with the substrate, since the content of silicon carbide is higher than 70vol.%. Palladium-free activation and palladium activation are successful in using to render the substrate surfaces auto-catalytically active towards metal deposition in the electroless solution, and furthermore, the sensitization step in the conventional process has been omitted. The structure, morphology and component of the coated layers are clarified by means of XRD, SEM and EDAX. Also, microhardness and adhesion measurements are carried out. The study indicates that the uniform Ni–P film is a mixture of microcrystalline and crystalline phases in the alkaline bath, with excellent adhesion to the substrate; the values of microhardness are enhanced after coating nickel. [Copyright &y& Elsevier]

• Our samples consist of two groups: short GRBs with and without Extended Emission. • The samples show a bimodal distribution when peak photon flux is plot vs fluence. • sGRBs with EE tend to concentrate in the long duration segment. • We argue that sGRBs with EE come from the coalescence of neutron stars. • On the contrary, sGRBs without EE should come from NS-BH mergers. GRB 170817A was confirmed to be associated with GW170817, which was produced by a neutron star - neutron star merger. It indicates that at least some short gamma-ray bursts come from binary neutron star mergers. Theoretically, it is widely accepted that short gamma-ray bursts can be produced by two distinctly different mechanisms, binary neutron star mergers and neutron star - black hole mergers. These two kinds of bursts should be different observationally due to their different trigger mechanisms. Motivated by this idea, we collect a universal data set constituted of 51 short gamma-ray bursts observed by Swift /BAT, among which 14 events have extended emission component. We study the observational features of these 51 events statistically. It is found that our samples consist of two distinct groups. They clearly show a bimodal distribution when their peak photon fluxes at 15–150 keV band are plotted against the corresponding fluences. Most interestingly, all the 14 short bursts with extended emission lie in a particular region of this plot. When the fluences are plotted against the burst durations, short bursts with extended emission again tend to concentrate in the long duration segment. These features strongly indicate that short gamma-ray bursts really may come from two distinct types of progenitors. We argue that those short gamma-ray bursts with extended emission come from the coalescence of neutron stars, while the short gamma-ray bursts without extended emission come from neutron star - black hole mergers. [ABSTRACT FROM AUTHOR]

A new facility called CAFE2 (Chinese Accelerator Facility for super heavy Elements) has been constructed and put into routine operation at Institute of Modern Physics (IMP) in 2021. To meet the requirement of metallic ions, we assembled a room-temperature ECR ion source-LECR5 (Lanzhou Electron Cyclotron Resonance ion source No.5) as its injector. This paper mainly introduces the results of optimization of metallic ions, including 40Ca, 48Ca, 54Cr and 55Mn, with inductive heating metal oven. Calcium ions was produced by direct heating of the mixture powder of calcium oxide and aluminum. Chromium and manganese ions were obtained by heating of isotopic pure elemental materials. With different supporting gas, 1–5 puA of metallic ions have been produced and delivered to the accelerator successfully. Beam emittance and transmission efficiency will also be discussed in this paper. [ABSTRACT FROM AUTHOR]

The Low Energy heavy-ion Accelerator Facility (LEAF) is a low-energy, high-intensity, heavy ion accelerator for multidisciplinary research developed at the Institute of Modern Physics (IMP). Beam commissioning of the facility began in 2018, but until recently, only a fixed beam energy of 0.5 MeV/u was available because the main accelerator structure is a Radio-Frequency Quadrupole (RFQ), which hinders LEAF to meet the requirements of the experimental terminals, for example, 12C+12C fusion reaction investigation at astrophysical energies requires beam energies adjustable from 0.3 MeV/u to 0.7 MeV/u. To expand the beam energy range, a "constant-beta" structure Drift Tube Linac (DTL) was developed providing an adjustable beam energy from 0.3 to 0.7 MeV/u. To control the beam quality, specifically the energy spread, two re-bunchers are employed, one upstream and one downstream of the DTL. Here we present the development of the key device: an Interdigital H-mode DTL (IH-DTL). First, we discuss the beam dynamics design for the beam energy adjustment system, then we present details of the test bench, and finally, we report measurements performed with the finished hardware. The measurements of energy adjustment and energy spread agree well with the simulations, demonstrating the feasibility of this design. [ABSTRACT FROM AUTHOR]

The role of serotonin 7 (5-HT 7 ) receptors in the regulation of depression is poorly understood, particularly in Parkinson’s disease-associated depression. Here we examined whether 5-HT 7 receptors in the prelimbic (PrL) sub-region of the ventral medial prefrontal cortex (mPFC) involve in the regulation of depressive-like behaviors in sham-operated rats and rats with unilateral 6-hydroxydopamine lesions of the medial forebrain bundle. The lesion induced depressive-like responses as measured by the sucrose preference and forced swim tests when compared to sham-operated rats. Intra-PrL injection of 5-HT 7 receptor agonist AS19 (0.5, 1 and 2 μg/rat) increased sucrose consumption, and decreased immobility time in sham-operated and the lesioned rats, indicating the induction of antidepressant-like effects. Further, intra-PrL injection of 5-HT 7 receptor antagonist SB269970 (1.5, 3 and 6 μg/rat) decreased sucrose consumption, and increased immobility time, indicating the induction of depressive-like responses. However, the doses producing these effects in the lesioned rats were higher than those in sham-operated rats. Neurochemical results showed that intra-PrL injection of AS19 (2 μg/rat) increased dopamine, 5-hydroxytryptamine (5-HT) and noradrenaline (NA) levels in the mPFC, habenula and ventral hippocampus (vHip) in sham-operated and the lesioned rats; whereas SB269970 (6 μg/rat) decreased 5-HT levels in the habenula and vHip, and the levels of NA in the mPFC, habenula and vHip in the two groups of rats. The results suggest that 5-HT 7 receptors in the PrL play an important role in the regulation of these behaviors, which attribute to changes in monoamine levels in the limbic and limbic-related brain regions after activation and blockade of 5-HT 7 receptors. [ABSTRACT FROM AUTHOR]

Abstract: Stress-induced martensitic transformation of as-sputtered and post-annealed Ti50.1Ni40.8Cu9.1 thin films was investigated using in-situ synchrotron X-ray diffraction (S-XRD) technique. For the as-deposited film, in-situ S-XRD analysis showed a martensitic transformation from parent phase to martensite during initial loading, followed by reorientation of martensite variants via detwinning. This detwinning process induced a strong 〈020〉 fiber texture along the loading direction and a strong 〈002〉 fiber texture perpendicular to the loading direction. For the 650°C annealed film, there is only elastic deformation, followed by a martensitic transformation during deformation. [Copyright &y& Elsevier]

Abstract: In the present study, we examined changes in the firing rate and firing pattern of putative slow-spiking (SS) and fast-spiking (FS) interneurons in medial prefrontal cortex (mPFC) and the effect of 5-hydroxytryptamine-3 (5-HT3) receptor agonist SR 57227A on the neuronal firing in rats with 6-hydroxydopamine lesions of the substantia nigra pars compacta (SNc) by using extracellular recording. The lesion of the SNc in rats decreased the firing rate of FS interneurons and the firing pattern of both SS and FS interneurons changed towards a more burst-firing. Systemic administration of SR 57227A (40–640 μg/kg, i.v.) increased the firing rate of SS interneurons, and decreased FS interneurons in sham-operated and the lesioned rats, respectively. The doses producing excitation or inhibition in the lesioned rats were higher than sham-operated rats. The local application of SR 57227A (0.01 μg) in mPFC excited SS interneurons, and inhibited FS interneurons in sham-operated rats, while having no effects on firing rate in the lesioned rats. Systemic administration of GABAA receptor antagonist bicuculline (2 mg/kg, i.v.) excited FS interneurons in sham-operated rats, whereas bicuculline did not change the activity of FS interneurons in the lesioned rats. Our findings indicate that the putative SS and FS interneurons activity is modulated through activation of 5-HT3 receptor by direct or indirect action, and the lesion of the SNc leads to changes in firing activity of the SS and FS interneurons and decreased response of these interneurons to SR 57227A, suggesting dysfunction and/or down-regulation of 5-HT3 receptor on interneurons in the 6-hydroxydopamine-lesioned rats. [ABSTRACT FROM AUTHOR]

Abstract: AZ31 magnesium alloys were implanted with tantalum ions with doses of 1×1016, 5×1016 and 1×1017 ions/cm2, using a metal vapor vacuum arc (MEVVA) at an extraction voltage of 45kV. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) analysis suggested that tantalum ions implantation promoted the formation of the pre-oxidation layer and a new Ta2Al phase was formed in the implanted layer. Then, the oxidation kinetics of the implanted specimens was investigated by isothermal oxidation at 773K in pure O2 up to 90min. The results showed that after implantation treatments the oxidation resistance of the specimens was significantly improved and the specimen with the highest dose had the best oxidation resistance. Finally, the mechanism of the anti-oxidation effects was also discussed. [Copyright &y& Elsevier]

Abstract: The oxidation kinetics of MgNd alloys oxidized in pure O2 at high temperatures has been investigated. The results revealed two stages of the reaction: A fast initial oxidation was followed by a slow oxide growth with a parabolic kinetics. For MgNd alloys (Nd=25wt.%), the oxidation rate increased with the enhancement of the oxidation temperature. A sudden ignition was found for this alloys oxidized at 873K up to about 80min. Moreover, the increase of the Nd content would harm the oxidation resistance of the MgNd alloys. By Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis, it was found that a triplex structure of oxide film formed. The outer layer was composed of MgO, Nd2O3 and Nd(OH)3, the middle layer mainly consisted of MgO and Nd2O3, and the inner layer was the transitional layer made of MgO, Nd2O3 and the content of the substrate. The protective oxidation was associated with the formation of the dense Nd2O3/MgO layer during isothermal oxidation process. The oxidation mechanisms for the formation of oxide film are discussed. [Copyright &y& Elsevier]

Abstract: SiCGe/SiC heterojunction structure is required in development of SiC optoelectronic devices and light-activated switching devices. We present in this paper a primary attempt to grow the ternary alloy SiCGe on SiC substrates under varied growth conditions in a conventional hot-wall CVD system. SiH4, GeH4 and C3H8 were employed as silicon, germanium and carbon sources, respectively. The samples were measured by means of SEM, XPS, XRD, optical absorption, etc. Two different growth modes i.e., island growth and porous growth were observed. It has been shown that germanium atoms can be effectively incorporated into the ternary alloys, which makes their optical gaps to be narrowed with increasing Ge content. However, incorporation of Ge induces a heavy lattice mismatch, which limits the film thickness by the formation of mismatch defects. It has been shown that use of a buffer layer can effectively improve the growth quality of the ternary alloy. [Copyright &y& Elsevier]

An experimental study was carried out to evaluate quantitatively the loads acting on the diamond grits during the circular sawing of two kinds of typical granite with a diamond segmented saw blade. Measurements were made of the horizontal and vertical force components and the consumed power in order to obtain the tangential and the normal force components. The temperatures at the diamond–granite contact zone were measured using a foil thermocouple, the measurements, together with the net sawing power, being used subsequently to estimate the energy partition to the granite by a temperature matching technique. Based on the energy partition values, tip temperatures at individual cutting points were estimated using an analytical model. SEM was used to follow the topographies of worn diamond segments. The average force acting on each diamond grit was found to be only 4% of the diamond compressive strength measured by a static method. The strength disparity of diamond grits and the random protrusion of grits beyond the bond matrix should be significant factors in accounting for the wear of diamond grits. The wear of diamond grits was also found to be closely related to the high temperatures generated at individual cutting points and the pop-out of diamonds from the bond matrix were attributed to the heat conducted to the segments. [Copyright &y& Elsevier]