Surface energies in high-entropy carbides with variable carbon stoichiometry

The carbon vacancy in high-entropy carbides (HECs) has a significant impact on their physical and chemical properties, yet relevant studies have still been relatively few. In this study, we investigate the surface energies of HECs with variable carbon vacancies through first-principles calculations. The results show that the surface energy of the (1 0 0) surface of the stoichiometric HECs is significantly lower than that of (1 1 1) surface. With the decrease in carbon stoichiometry, the surface energies of both (1 0 0) and (1 1 1) surfaces increase gradually, which is mainly due to the weakening of covalent bonding and the decrease of metal Hirshfeld-I (HI) charges. However, the surface energy of (1 0 0) surface increases more quickly than that of (1 1 1) surface and will exceed that of (1 1 1) surface when the carbon stoichiometry decreases to a certain extent, which is primarily attributed to the greater decrease rate of metal HI charges of (1 0 0) surface.     

Rapid anti-solvent vapor-assisted synthesis of CsPbBr3/Cs4PbBr6 microcrystals with high brightness and stability of green light emission

Journal of Materials Science - The CsPbBr3/Cs4PbBr6 perovskite composite material has received wide attention due to its good stability and photoelectric properties, and it is promising to appear...     

An Efficient Approach for Nodal Water Demand Estimation in Large-scale Water Distribution Systems

Water Resources Management - Real-time modeling of a water distribution system (WDS) is a critical step for the control and operation of such systems. The nodal water demand, as the most important...     

Mimic Drug Dosage Modulation for Neuroplasticity Based on Charge-Trap Layered Electronics

The human brain is often likened to an incredibly complex and intricate computer, rather than electrical devices, consisting of billions of neuronal cells connected by synapses. Different brain circuits are responsible for coordinating and performing specific functions. The reward pathway of the synaptic plasticity in the brain is strongly related to the features of both drug addiction and relief. In the current study, a synaptic device based on layered hafnium disulfide (HfS₂) is developed for the first time, to emulate the behavioral mechanisms of drug dosage modulation for neuroplasticity. A strong gate-dependent persistent photocurrent is observed, arising from the modulation of substrate-trapping events. By controlling the polarity of gate voltage, the basic functions of biological synapses are realized under a range of light spiking conditions. Furthermore, under the control of detrapping/trapping events at the HfS₂/SiO₂ interface, positive/negative correlations of the A_n/A₁ index, which significantly reflected the weight change of synaptic plasticity, are realized under the same stimulation conditions for the emulation of the drug-related addition/relief behaviors in the brain. The findings provide a new advance for mimicking human brain plasticity.     

Optimization of room-temperature TCR of polycrystalline La0.9-xSrxK0.1MnO3 ceramics by Sr adjustment

High-density La_0.9-xSr_xK_0.1MnO₃ ceramics (LSKMO, A-site = La, Sr and K, 0 ≤ x ≤ 0.25) are successfully fabricated by using facile sol-gel method. Electrical properties are performed by using combination of phenomenological percolation (PP) model, double exchange (DE) mechanism, and Jahn-Teller (JT) effect. Moreover, X-ray diffraction and scanning electron microscopy are employed to analyze the structure and morphology of LSKMO ceramics. Valence states and ionic stoichiometry are assessed by using X-ray photoemission spectrometry. Results reveal that Sr²⁺ ions, substituting La³⁺ ions, significantly influenced DE mechanism and JT effect. In addition, Sr-doping plays essential role in improving electrical properties of LSKMO ceramics. At optimal doping content of x = 0.09, peak temperature coefficient of resistance (TCR) of the resistivity is found to be 11.56% K^?1 at 297.15 K, which is optimal TCR for A-site K-occupied perovskite manganese oxides. These results confirm that polycrystalline LSKMO ceramics render high room-temperature TCR values due to Sr-doping.     

Improving Properties of Poly(vinylidene fluoride) by Adding Expanded Graphite without Surface Modification via Water‐Assisted Mixing Extrusion

Expanded graphite (EG) is introduced into poly(vinylidene fluoride) (PVDF) by melt mixing extrusion with water injection. The results demonstrate that the unfunctionalized EG in composite prepared with water injection exbibits better dispersion than that in the one prepared without water injection due to the promoting role of water during extrusion. Thus, the PVDF/EG composite with loading of 4 wt% prepared by water‐assisted mixing extrusion (WAME) exhibits electrical conductivity of about three orders of magnitude higher than the neat PVDF and one order of magnitude higher than the one prepared without water injection. Comparing to the neat PVDF, the thermal conductivity of the composites prepared with and without water injection is increased by 101.5% and 75.0%, respectively. The introduced EG leads to increased Young’s modulus and tensile strength especially for the composite prepared by WAME. The present work indicates that WAME can promote the dispersion of EG in PVDF matrix without any extra functionalization.     

Efficient digital holographic 3d human image reconstruction and improvement on mobile devices

Advanced digital holography attracts a lot of attentions for 3D visualization nowadays. The representation of high-resolution digital holographic 3D human images suffers from computational inefficiency on the mobile devices due to the limited hardware for digital holographic processing. Specifically, to reconstruct the high-quality holographic image needs to compensate for the phase aberration, which needs lots of expensive optical hardware components to acquire measurements such as different axial distances, illumination angles, wavelengths, polarization states, and so on. To reduce computational complexity in digital holographic 3D human image reconstruction, we propose an efficient and effective algorithm to simplify Fresnel transforms for the mobile devices. Our algorithm reduces the number of FFTs and fastens the calculation of the exponential function in the Fresnel integral for the digital holography image reconstruction. Specifically, we reformulate the Fresnel integral and use a polynomial approximation to approximate the exponential function. In the holographic image quality improvement, we modify a maximum a posteriori (MAP) estimation to improve the quality of the reconstructed holographic 3D image restoration. Our algorithm outperforms previous approaches in not only smaller running time but also the better quality of the digital holographic 3D human image representation for the mobile devices.

     

Effects of argon sintering atmosphere on luminescence characteristics of Ca6BaP4O17:Sm3+ phosphors

In this paper, Ca₆BaP₄O₁₇:Sm³⁺ and Li⁺ co-doped Ca₆BaP₄O₁₇:Sm³⁺ phosphors were synthesized in air and argon atmospheres using a solid-state reaction method. The phosphor morphologies and crystal structure were studied using scanning electron microscopy and X-ray diffraction, respectively. The emission and absorption characteristics were investigated using photoluminescence emission spectroscopy and diffuse reflectance spectroscopy. The surface states and composition of phosphor were investigated using X-ray photoelectron spectroscopy. The emission integrated intensities of the phosphors sintered in an argon atmosphere increased 3.5 fold than the ones sintered in air atmosphere, with Li⁺ ions becoming embedded in the lattice of the Ca₆BaP₄O₁₇:Sm³⁺ phosphor. This occurs because there are fewer defect/oxygen vacancies and less of the secondary phase forms, leading to better Sm³⁺ emission. The results suggest that sintering a mixture of the raw materials of a phosphor in an argon atmosphere is a good approach for synthesizing Ca₆BaP₄O₁₇:Sm³⁺ phosphor powders. The color purity and CIE values of an optimized phosphor sample sintered in an argon atmosphere with an Li⁺ ion compensator were calculated to be ~ 99.6% and (0.612,0.386) in the orange–red region under 405-nm excitation, respectively. Moreover, the solid solubility of Sm³⁺ ions in the Ca₆BaP₄O₁₇ host can be enhanced by using an argon atmosphere in the synthesis process.     

化香果提取物体外抑菌活性研究

研究了化香果提取物对水产常见9种致病菌嗜水气单胞菌（Aeromonas hydrophila）、温和气单胞菌（Aeromonas sobria）、豚鼠气单胞菌（Aeromonas caviae）、维氏气单胞菌（Aeromonas veronii）、迟钝爱德华菌（Edwardsiella tarda）、副溶血弧菌（Vibrio parahaemolyticus）、鼠疫耶尔森氏菌（Yersinia pestis）、大肠杆菌（Escherichia coli）和金黄色葡萄球菌（Staphylococcus aureus）的抑菌活性。研究结果表明：化香果提取物对9种细菌均具有抑制作用，最小抑菌浓度为4.50 g/L。对每种细菌而言，抑菌效果随化香果提取物质量浓度的增加而增强，其中对大肠杆菌的抑制能力最强，IC₅₀值为0.035 g/L；金黄色葡萄球菌次之，IC₅₀值为0.053 g/L。对雌雄小鼠急性经口毒性试验结果表明化香果提取物对小鼠的急性经口半数致死量（LD₅₀值）分别为5 010和7 940 mg/kg体质量，表明化香果提取物属于实际无毒级。