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Studies on GaAsBi-based devices have been deeply carried out in recent years, strongly driven by their excellent performance. Despite the growing interest in GaAsBi, the systematic researches on its vibrational and thermodynamic properties are still lacking. Hence, in this work, the structural, vibrational and thermodynamic properties of GaBixAs1-x are studied systematically by performing ab initio calculations. Firstly, the calculation structure constants of GaBixAs1-x are in accordance with other available data in the literature. Next, the results of the vibrational frequencies indicate that the phonon frequencies of GaBixAs1-x undergo a sharp decline when the bismuth concentration x is elevated. Besides the reduction of the phonon densities of states at the specified wave vector, the optical branches of GaBixAs1-x narrow and the attenuation of longitudinal modes is greater than that of transverse modes with the enhancement of the Bi concentration x. Then, the splitting degree $$\left( {\delta \omega } \right)$$ suggests that the ionic strength for GaBixAs1-x is declined when increasing the Bi composition. Finally, the thermodynamic functions of GaBixAs1-x ranging from $$\Delta F$$ , $$\Delta E$$ , $$C_{v}$$ and $$S$$ are predicted. In addition, the calculation values of the Debye temperature for GaBixAs1-x also confirm the change trend of phonon frequencies of the system.

RGAs are widely used in molecular component examination, impurity analysis, leak detection and test of vacuum system performance. However, RGAs have different sensitivities to different gases, and the sensitivities can change quickly and depend on so many parameters, which make its ability severely limited. In this work we established a new practical method to precisely measure noble gas ratio of argon -xenon gas mixture. Gaseous argon and xenon were controlled, respectively, by two mass flow controller (MFC). A variable leak valve (VLV) was used to introduce the gas mixture sample into the RGA measurement chamber. Gas mixtures with xenon concentration from 200ppm to 20000ppm (by mass) were introduced and tested by RGA. The time stability of RGA-measurement system was optimized to 2.1%. A good linearity of MFC-RGA response was achieved, verifying the reliability of RGA in measuring noble gas mixture with component concentration down to several hundred ppm level. Since the approach we used in our experiment is gas-species independent, we believe that it can be popularized to other gas species when properly applied.

Autism spectrum disorder (ASD), a group of neurodevelopmental disorders characterized by social communication deficits and stereotyped behaviors, may be associated with changes to the gut microbiota. However, how gut commensal bacteria modulate brain function in ASD remains unclear. Here, we used chromodomain helicase DNA-binding protein 8 (CHD8) haploinsufficient mice as a model of ASD to elucidate the pathways through which the host and gut microbiota interact with each other. We found that increased levels of amino acid transporters in the intestines of the mouse model of ASD contribute to the high level of serum glutamine and the increased excitation/inhibition (E/I) ratio in the brain. In addition, elevated α-defensin levels in the haploinsufficient mice resulted in dysregulation of the gut microbiota characterized by a reduced abundance of Bacteroides. Furthermore, supplementation with Bacteroides uniformis improved the ASD-like behaviors and restored the E/I ratio in the brain by decreasing intestinal amino acid transport and the serum glutamine levels. Our study demonstrates associations between changes in the gut microbiota and amino acid transporters, and ASD-like behavioral and electrophysiology phenotypes, in a mouse model.

The Cu–In binary system is receiving increasing attention due to its application in the low-temperature assembly of heat-sensitive devices. Nevertheless, the fundamental behaviors of this binary system are very difficult to study because of the extreme softness of indium. This difficulty was successfully overcome in this study, and the phase stabilities and chemical reactions were established. Binary Cu–In diffusion couples were prepared by electroplating In onto a Cu substrate. During the plating process, CuIn2 formed even though this intermetallic is not present in the Cu–In binary phase diagram. It was established in this study that CuIn2 is indeed a stable phase below 100 °C, but decomposes at a temperature between 100 and 120 °C. In addition, the microstructure evolution during solid-state aging at 100, 120, and 140 °C was investigated. The hardness values and Young’s moduli for CuIn2 and Cu11In9 were measured by using nanoindentation.

Landslides at river embankments can block watercourses, imperiling the safety of vessels and downstream hydropower stations. The Baige landslide, which occurred on 11th October 2018, is taken as an example to study the landslide motion and landslide-generated wave evolutions. The elasto-viscoplastic and renormalization group (RNG) turbulence models are employed in the FLOW3D software, treating the motion of the Baige landslide as a viscous flow. Numerical results show that the maximum velocity of the slide was approximately 75 m/s when entering the Jinsha River. Further, the waves triggered by massive debris avalanches at three different locations are investigated. The maximum velocity of the landslide-generated wave and the maximum run-up in the Jinsha River reached 45 m/s and 53.9 m, respectively, on the slide axis. The maximum run-up terrain elevation of the wave was 3039.7 m. The simulation results are basically consistent with the actual field observations and fit well with high-speed flow-like landslides. In this case, the displaced water was dominant due to the significant volume of the failure mass and the shallow watercourse of the Jinsha River. The run-down waves located on the source region axis contribute to the rise of water level downstream and upstream. The results from this case study serve as a practical inspiration for research on disaster processes.

Liquid noble gases are widely used as targets in low background search experiments, particularly in direct dark matter search experiments. 83mKr is an excellent low-energy internal calibration source for future larger liquid noble gas detectors. To calibrate liquid argon detector with 83mKr in different drift fields and to study the correlation between light yield and drift fields. A dual-phase LAr prototype detector was designed to study the 83mKr responses in liquid argon. 83mKr atoms are produced through the decay of 83Rb and introduced into the LAr detector through the circulating purification system. We report that the light yield reaches 7.26 ± 0.02 pe/keV for 41.5 keV from 83mKr and 7.66 ± 0.01 pe/keV for 511 keV from 22Na, as a comparison. After stopping the fill, the rate decays of 83mKr are with a fitted half-life of 1.83 ± 0.11 h, which is consistent with the reported value of 1.83 ± 0.02 h. The light yield that varies with the drift electric field from 0 to 200 V/cm has also been reported.

The elastic anisotropic, band structure, optical and lattice dynamical properties of ZnGeP2 have been investigated via density functional theory and density functional perturbation theory. The calculated lattice constants and elastic constants of ZnGeP2 are in good agreement with the previous results. The anisotropy in elasticity has been visualized by three-dimensional surfaces and the planar projection contours. ZnGeP2 shows an obvious elastic anisotropy under zero pressure, and the anisotropy increases with the increase in pressure. The hybrid functional HSE06 is used to evaluate the electronic properties of ZnGeP2, and the results suggests that the HSE06 hybrid functional can obtain more reasonable band structure. ZnGeP2 shows direct band gap of 2.06 eV. In addition, the optical spectrum is derived for photon energies up to 40 eV. The phonon frequencies at the Brillouin zone center are calculated and discussed.

All-sky meteor radars are primarily used for meteor observations. This paper reports the first observations of ionospheric E-region field-aligned irregularities (FAIs) from a conventional all-sky meteor radar located at Wuhan (31°N, 114°E) for the period of March–June 2018. E-region FAI echoes evident in range-time intensity (RTI) maps show quasiperiodic striations with positive and negative slopes, which are consistent with multiple FAI structures moving across the wide beam of the meteor radar. A statistical analysis shows that out of a total of 111 d, there are 73 d with E-region FAI echoes detected by the meteor radar. The FAI events correspond well with the presence of sporadic-E layers which provide the necessary plasma density gradient for the development of gradient drift instability producing FAIs. The results demonstrate the capability of conventional meteor radars to make simultaneous routine observations of meteors and ionospheric E-region FAIs through incorporating RTI and spectral analysis into the online realtime data processing. Meteor radar observations could potentially address the limitations of ionospheric radars, which cannot provide simultaneous measurements of neutral winds and irregularity structures, and thereby contribute to better understanding of the dynamical processes producing E-region irregularities.

Tigecycline is one of the last-resort antibiotics to treat complicated infections caused by both multidrug-resistant Gram-negative and Gram-positive bacteria1. Tigecycline resistance has sporadically occurred in recent years, primarily due to chromosome-encoding mechanisms, such as overexpression of efflux pumps and ribosome protection2,3. Here, we report the emergence of the plasmid-mediated mobile tigecycline resistance mechanism Tet(X4) in Escherichia coli isolates from China, which is capable of degrading all tetracyclines, including tigecycline and the US FDA newly approved eravacycline. The tet(X4)-harbouring IncQ1 plasmid is highly transferable, and can be successfully mobilized and stabilized in recipient clinical and laboratory strains of Enterobacteriaceae bacteria. It is noteworthy that tet(X4)-positive E. coli strains, including isolates co-harbouring mcr-1, have been widely detected in pigs, chickens, soil and dust samples in China. In vivo murine models demonstrated that the presence of Tet(X4) led to tigecycline treatment failure. Consequently, the emergence of plasmid-mediated Tet(X4) challenges the clinical efficacy of the entire family of tetracycline antibiotics. Importantly, our study raises concern that the plasmid-mediated tigecycline resistance may further spread into various ecological niches and into clinical high-risk pathogens. Collective efforts are in urgent need to preserve the potency of these essential antibiotics. Plasmid-encoded tet(X) genes from Escherichia coli in China confer high-level tigecycline resistance.

Three new perovskite-like hybrid iodobismuthates with two quaternary ammonium cations, namely (BnNEt3)3(Bi2I9) (1) (BnNEt3)4(Bi4I16) (2) and (n-Bu4N)2n(Bi4I14)n (3) (Bn = benzyl, n-Bu = n-butyl), have been synthesized by reacting BiI3 with the quaternary ammonium iodide in molar ratio 2:3 (1), 1:1(2), and 2:1 (3), respectively. All hybrids were characterized by elemental analysis, X-ray diffraction and UV–Vis spectroscopic analysis. Single-crystal X-ray diffraction revealed that hybrids 1 and 2 are di-nuclear and tetra-nuclear cluster structures respectively, while 3 is a polymeric chain structure based on a (Bi4I14) tetra-nuclear cluster unit. Their optical band-gaps have been determined as 2.19 eV(1), 2.16 eV(2), 2.02 eV(3), respectively. The optical band gaps exhibit a structure-related decrease from 1 to 3, in agreement with their color changes and the density functional theory (DFT) calculation results. The DFT calculations also reveal that there is a inversely proportional relationship between the optical Eg and the aggregation degree of the BiI6 octahedra in the hybrid iodobismuthate clusters.

Hydroxide exchange membrane fuel cells offer possibility of adopting platinum-group-metal-free catalysts to negotiate sluggish oxygen reduction reaction. Unfortunately, the ultrafast hydrogen oxidation reaction (HOR) on platinum decreases at least two orders of magnitude by switching the electrolytes from acid to base, causing high platinum-group-metal loadings. Here we show that a nickel-molybdenum nanoalloy with tetragonal MoNi4 phase can catalyze the HOR efficiently in alkaline electrolytes. The catalyst exhibits a high apparent exchange current density of 3.41 milliamperes per square centimeter and operates very stable, which is 1.4 times higher than that of state-of-the-art Pt/C catalyst. With this catalyst, we further demonstrate the capability to tolerate carbon monoxide poisoning. Marked HOR activity was also observed on similarly designed WNi4 catalyst. We attribute this remarkable HOR reactivity to an alloy effect that enables optimum adsorption of hydrogen on nickel and hydroxyl on molybdenum (tungsten), which synergistically promotes the Volmer reaction., The lack of efficient and cost-effective catalysts for hydrogen oxidation reaction (HOR) hampers the application of hydroxide exchange membrane fuel cells. Here, authors reported bimetallic MoNi4 and WNi4 nanoalloys with marked HOR activity in alkali, among which MoNi4 outperforms the Pt/C catalyst.

CoFe films without buffer layers were deposited at different ultra-low argon pressures ranging from 0.085 to 0.847 mTorr. This pressure range was one to two orders lower than the normal sputtering pressure. As a consequence, the static magnetic properties, including coercivity and magnetic anisotropy field, were improved with decrease argon pressure. The high-frequency permeability spectra showed that the resonance frequency and the damping factor of the films also reached optimal values at ultra-low pressure. Basing on atomic force microscopy observations, we attributed the excellent properties to the improved morphologies of the films and released internal stress.