Towards the object-oriented design of active hydrogen evolution catalysts on single-atom alloys

Given a desired property, locating relevant materials is always highly desired but very challenging in a range of areas, including heterogeneous catalysis. Obviously, object-oriented design/screening is an ideal solution to this problem. Herein, we develop an inverse catalyst design workflow in Python (CATIDPy) that utilizes a genetic-algorithm-based global optimization method to guide on-the-fly density functional theory calculations, successfully realizing the highly accelerated location of active single-atom alloy (SAA) catalysts for the hydrogen evolution reaction (HER). 70 binary and 752 ternary SAA candidate catalysts are identified for the HER. Furthermore, via considering the segregation stability and cost of materials, we extracted 6 binary and 142 ternary SAA candidate catalysts that are recommended for experimental synthesis. Remarkably, guided by these theoretical identifications, homogeneously dispersed Ni-based bimetallic catalysts (e.g., NiMo, NiAl, Ni₃Al, NiGa, and NiIn) were synthesized experimentally to test the reliability of the CATIDPy workflow, and they showed superior HER performance to bare Ni foam, indicating huge potential for use in real-world water electrolysis techniques. Perhaps more importantly, these results demonstrate the capacity of such a proposed approach for investigating unexplored chemical spaces to efficiently design promising catalysts without knowledge from the expert domain, which has far-reaching implications.

An inverse catalyst design workflow in Python (CATIDPy) for discovering unexplored chemical spaces successfully realized the highly accelerated location of active single-atom alloy (SAA) catalysts for the hydrogen evolution reaction (HER).     

A simple and sensitive fluorescence quenching method for the determination of H(2)O(2) using Rhodamine B and FE(3)O(4) nanocatalyst

In pH 1.99 sodium acetate-HCl buffer solutions at 60 °C, Rhodamine B exhibited a strong fluorescence peak at 584 nm using an excitation wavelength of 548 nm. The fluorescence quenching occurred when Fe₃O₄ nanoparticles catalyzed H₂O₂ oxidation of Rhodamine B. Under the chosen conditions, the fluorescence intensity at 584 nm decreased when the concentration of H₂O₂ increased. The fluorescence quenching intensity is linear with the concentration of H₂O₂ in the range of 10–200 nmol/L. Thus, a new and simple and sensitive nanocatalytic fluorescence method was proposed for the determination of H₂O₂ in synthetic sample, with satisfactory results.     

A railway track dynamics model based on modal substructuring and a cyclic boundary condition

This article presents a technique for modelling the coupled dynamics of a railway vehicle and the track. The method is especially useful for simulating the dynamics of high speed trains running on nonlinear tracks. The main hypothesis is a cyclic system: an infinite track on which there is an infinite set of identical vehicles spaced at a regular interval of distance. Thus the main problems of the finite-length track models (e.g. the waves that reflect at the end of the track and interact with the vehicle; and the time interval of integration must be shorter than the track length divided by the velocity) are avoided. The flexibility of the method can be observed from the case studies presented in the present work: a vehicle passing over a hanging sleeper, and the vehicle-track dynamics for different ballast compaction cases. The results show the influence of the hanging sleeper gap on the wheel-rail contact forces, and the bending moment at the sleeper for different ballast compaction cases.     

Information hiding based on the optical interference principle

An information hiding method based on the optical interference principle is proposed. In this method, a secret image can be obtained by two light beams' interference. One of the beams is modulated by our assigned host image; and the other is modulated by a noise-like complex distribution, which is regard as the encrypted image. The transmission of the encrypted image can be implemented by hiding it in the host image to prevent the communication from being perceived by unauthorized person. In addition, this method can also realize simultaneous encryption and hiding for two images. A series of numerical simulation results are presented to verify the feasibility of our proposed method.     

A Physical experimental study of variable-order fractional integrator and differentiator

Recent research results have shown that many complex physical phenomena can be better described using variable-order fractional differential equations. To understand the physical meaning of variable-order fractional calculus, and better know the application potentials of variable-order fractional operators in physical processes, an experimental study of temperature-dependent variable-order fractional integrator and differentiator is presented in this paper. The detailed introduction of analogue realization of variable-order fractional operator, and the influence of temperature to the order of fractional operator are presented in particular. Furthermore, the potential applications of variable-order fractional operators in PI ^λ(t) D ^μ(t) controller and dynamic-order fractional systems are suggested.     

Novel electrospun PAN�CPVC composite fibrous membranes as polymer electrolytes for polymer lithium-ion batteries

Composite fibrous membranes based on poly(acrylonitrile)(PAN)-poly(vinyl chloride)(PVC) have been prepared by electrospinning. The fibrous membranes are made up of fibers of 850- to 1,300-nm diameters. These fibers are stacked in layers to produce a fully interconnected pore structure. Polymer electrolytes were prepared by immersing the fibrous membranes in 1 M LiClO₄-PC solution for 60 min. The condition of pure PAN polymer electrolytes is jelly, which has poor mechanical performance and cannot be used. But when PVC with a good mechanical stiffener was added to PAN, the condition of composite PAN?CPVC polymer electrolytes becomes free-standing. In addition, the optimum electrochemical properties have been observed for the polymer electrolyte based on PAN?CPVC (8:2, w/w) to show ionic conductivity of 1.05?×?10^?3 S cm^?1 at 25 °C, anodic stability up to 4.9 V versus Li/Li⁺, and a good compatibility with lithium metal resulting in low interfacial resistance. The promising results showed that fibrous PEs based on PAN?CPVC (8:2, w/w) have good mechanical stability and electrochemical properties. This shows a great potential application in polymer lithium-ion batteries.     

光纤分布式扰动传感器中瑞利和受激布里渊散射光谱特性及其影响研究

针对光纤分布式扰动传感器长距离应用定位误差增大的问题,研究了传感器长距离光纤中的瑞利散射和受激布里渊散射的光谱特性及其对系统定位精度的影响.建立了长距离光纤中瑞利和受激布里渊散射的数学模型,通过仿真研究发现散射光波的杂波干涉和强度噪声会严重降低干涉仪的光学信噪比,从而导致定位误差.通过实验验证了仿真结果的正确性.研究结...     

适配体修饰金硒纳米合金共振散射光谱法检测痕量Hg2+

用硼氢化钠还原法制备了金硒(AuSe)纳米合金.用单链核酸适配体(aptamer)修饰AuSe纳米合金制备了汞离子的核酸适配体纳米探针(Apta-AuSe).在pH 6.8 Na2HPO4-NaH2PO4缓冲溶液中及NaCl存在下,Apta-AuSe纳米探针亦不聚集;当Hg2+存在时,它可以稳定aptamer序列中的T...     

Tunable radiation source by coupling laser-plasma-generated electrons to a periodic structure

Near-infrared radiation around 1000 nm generated from the interaction of a high-density MeV electron beam, obtained by impinging an intense ultrashort laser pulse on a solid target, with a metal grating is observed experimentally. Theoretical modeling and particle-in-cell simulation suggest that the radiation is caused by the Smith-Purcell mechanism. The results here indicate that tunable terahertz radiation with tens GV/m field strength can be achieved by using appropriate grating parameters.     

Frabicating hydroxyapatite nanorods using a biomacromolecule template

Rod-like hydroxyapatite (HAp) nanoparticles with various aspect ratios are synthesized by means of low-temperature hydrothermal method in the presence of a N-[(2-hydroxy-3-trimethylammonium) propyl]chitosan chloride (HTCC) template. The synthesized HAps were examined by X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR) and transmission electron microscopy (TEM) techniques. The results reveal that HAps are rod-like monocrystals, where the size and morphology can be tailored by varying synthesis conditions, such as pH, hydrothermal synthesis temperature and the ratio of PO₄³⁻ to the quaternary ammonium in HTCC. The mechanism of HTCC template on HAp nanorod preparation is analyzed.