Interfacial Superconductivity on the Topological Semimetal Tungsten Carbide Induced by Metal Deposition

Interfaces between materials with different electronic ground states have become powerful platforms for creating and controlling novel quantum states of matter, in which inversion symmetry breaking and other effects at the interface may introduce additional electronic states. Among the emergent phenomena, superconductivity is of particular interest. Here, by depositing metal films on a newly identified topological semimetal tungsten carbide (WC) single crystal, interfacial superconductivity is obtained, evidenced from soft point-contact spectroscopy. This very robust phenomenon is demonstrated for a wide range of metal/WC interfaces, involving both nonmagnetic and ferromagnetic films, and the superconducting transition temperatures are surprisingly insensitive to the magnetism of thin films. This method offers an opportunity to explore the long-sought topological superconductivity and has potential applications in topological-state-based spin devices.     

Nanoheterostructure by Liquid Metal Sandwich-Based Interfacial Galvanic Replacement for Cancer Targeted Theranostics

Nanoheterostructures with exquisite interface and heterostructure design find numerous applications in catalysis, plasmonics, electronics, and biomedicine. In the current study, series core–shell metal or metal oxide-based heterogeneous nanocomposite have been successfully fabricated by employing sandwiched liquid metal (LM) layer (i.e., LM oxide/LM/LM oxide) as interfacial galvanic replacement reaction environment. A self-limiting thin oxide layer, which would naturally occur at the metal–air interface under ambient conditions, could be readily delaminated onto the surface of core metal (Fe, Bi, carbonyl iron, Zn, Mo) or metal oxide (Fe₃O₄, Fe₂O₃, MoO₃, ZrO₂, TiO₂) nano- or micro-particles by van der Waals (vdW) exfoliation. Further on, the sandwiched LM layer could be formed immediately and acted as the reaction site of galvanic replacement where metals (Au, Ag, and Cu) or metal oxide (MnO₂) with higher reduction potential could be deposited as shell structure. Such strategy provides facile and versatile approaches to design and fabricate nanoheterostructures. As a model, nanocomposite of Fe@Sandwiched-GaIn-Au (Fe@SW-GaIn-Au) is constructed and their application in targeted magnetic resonance imaging (MRI) guided photothermal tumor ablation and chemodynamic therapy (CDT), as well as the enhanced radiotherapy (RT) against tumors, have been systematically investigated.     

Surface Tension Prediction Using Characteristics of the Density Profile Through the Interfacial Region

A simple surface tension estimation technique is described that is based solely upon the characteristics of the density profile in the interfacial region and the physical properties of the molecules in the fluid. This method, denoted free energy integration (FEI), links interfacial tension to known interfacial region density profile characteristics obtained via experiment or simulation. The general FEI methodology is provided here, and specific relations are derived for a methodology that incorporates the Redlich–Kwong fluid model. The Redlich–Kwong based FEI method was used to predict interfacial tension using the density profile characteristics of molecular dynamics (MD) simulations of argon using the Lennard–Jones potential, diatomic nitrogen using the two-center Lennard–Jones potential, and water using the extended simple point-charge (SPC/E) model. These results for argon compare favorably to values calculated by the traditional virial approach, known values from the literature using the finite-size scaling technique, and ASHRAE recommended values. In addition, the FEI predictions agree well with ASHRAE values and predictions using the virial method for nitrogen for the simulated range of temperatures in this study, and for water for reduced temperatures above 0.7. In addition, the FEI method results agree well with other established theoretical techniques for predictions of the surface tension of sulfur hexafluoride close to the critical point.     

Measurement of the Surface Tension of Undercooled Liquid Ti90Al6V4 by the Oscillating Drop Technique

The surface tension of liquid Ti₉₀Al₆V₄ was measured. The samples have been processed containerlessly by electromagnetic levitation, which allows the handling of highly reactive materials and measurements in the undercooled temperature region. The use of digital image processing allows the identification of oscillation modes and calculation of the surface tension from the l = 2 and m = 0, m = 2 oscillation modes. A linear least squares fit to the data showed the following temperature dependence: = 1.389 ± 0.09 – 9.017 × 10^–4 ± 5.64 × 10^–5(T – 1660°C) [Nm^–1]     

聚合物熔体界面张力测定方法的研究进展

在聚合物共混体系中,界面张力对聚合物相容性有着重要影响,决定着相与相之间的粘接性,成为控制其最终相态结构的一个重要因素,是研究多相聚合物相态结构的基础。文中综述了聚合物熔体界面张力的测定方法,这些测定方法主要有热力学方法、流变学方法以及动力学方法三大类;介绍了每种方法的基本原理,并对其优缺点及适用范围进行了简单说明。其中,动力学方法是使用最多、相对准确的,对该方法进行了重点介绍,并且讨论了动力学方法中熔体粘弹性对界面张力测定的影响。     

β因子校正法测定Pb-Cu、Bi-Cu合金表面张力

采用座滴法技术,通过“软件化”的自编 B-A 表和相应的β因子校正法程序,测定了 Pb-Cu,Bi-Cu 合金的表面张力。测定结果表明:Pb-7%wtCu 的元合金在850℃、900℃;Bi-26%Cu 二元合金在850℃的表面张力值分别为408×10~(-3)N·m~(-1)、427×10~(-3)N·m~(-1)以及343×10~(-3)N·m~(-1)。分析和讨论了测量与计算过程中的影响因素。     

Light‐Induced Shape Morphing of Liquid Metal Nanodroplets Enabled by Polydopamine Coating

Shape morphing nanosystems have recently attracted much attention and a number of applications are developed, spanning from autonomous robotics to drug delivery. However, the fabrication of such nanosystems remains at an early stage owing to limited choices of strategies and materials. This work reports a facile method to fabricate liquid metal (LM) nanodroplets by sonication of bulk LM in an aqueous dopamine hydrochloride solution and their application in light‐induced shape morphing at the nanoscale. In this method, dopamine acts as a surfactant, which stabilizes the LM nanodroplets dispersion during the sonication, and results in downsizing of the nanodroplets. Furthermore, by adding 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol to the suspension, self‐polymerization of dopamine molecules occurs, resulting in the formation of polydopamine (PDA)‐coated LM nanodroplets. Owing to the high photothermal conversion of the PDA, PDA‐coated LM nanodroplets are transformed from spherical shapes to ellipsoids by NIR laser irradiation. This study paves a simple and reliable pathway for the preparation of functional LM nanodroplets and their application as shape‐morphing nanosystems.     

金属丝拉伸夹具的开发及应用

金属丝拉伸试验是丝材力学性能测试的重要部分,而目前缺少有效的夹具和个性化的试验方案,使得金属丝拉伸性能测试成为难点。根据金属丝的结构特点设计了专门用于金属丝拉伸性能测试的夹具,可适用于直径为0.6~8.0mm的金属丝,并根据金属丝强度高、直径小、断后伸长率小等特点选用了100kN的拉伸试验机进行试验。结果表明:该金属丝拉伸夹具可以与100kN拉伸试验机配合较好,参照GB/T 228.1-2010对金属丝拉伸试验参数进行了个性化设置,实现了对金属丝拉伸性能的准确测试。     

Surface Tension and Viscosity of Succinonitrile– Acetone Alloys Using Surface Light Scattering Spectrometer

Using a surface light scattering spectroscopic technique, the surface tension and viscosity of pure succinonitrile (SCN) and SCN–acetone alloys at 0.86, 1.69, and 2.25 mol% have been determined. The surface light scattering technique, and the procedures used for making the alloys and measuring their concentrations, are presented. Analysis indicates our interfacial surface tension and viscosity measurements have an uncertainty of ±2% and ±10%, respectively. The surface tension and viscosity were measured at various temperatures yielding relations among surface tension, viscosity, temperature, and concentration in SCN–acetone alloys.     

电弧作用下AlSi5钎料在镀锌钢板上铺展及界面行为研究

采用 TIG 电弧钎焊试验方法,主要研究了电流大小、电弧加热时间以及弧长对 AlSi5钎料在镀锌钢板上润湿铺展及界面行为的影响。实验结果表明：随着电流、燃弧时间和某一范围内弧长的增加,钎料在镀锌钢板上的润湿角逐渐减小,铺展面积逐渐增加,并在某一特定范围时润湿铺展性能达到最佳;随着燃弧电流的增加,界面金属间化合物的厚度呈现先增加后减小的趋势,靠近母材一侧有 Fe2 Al5相生成,钎料一侧则生成 FeAl3相;Al 元素扩散到界面处与 Fe 元素发生扩散反应形成 Fe-Al 金属化合物颗粒,在钎缝中弥散分布着 Si 元素,对钎缝有强化作用。     

Preparations,Characteristics and Applications of the Functional Liquid Metal Materials

As new generation functional materials, the recently emerging low‐melting liquid metals have displayed many unconventional properties superior to traditional materials. Various methods, such as alloying, oxidizing, adding metals, or non‐metallic materials and so on, have been developed to prepare desirable functional materials based on the gallium or more other metals. These methods could not only change the form of the materials, but also endow the original liquid metals with rather diversified performances, which have further expanded the application range of the low‐melting liquid metals to meet various needs. This article aims to review and summarize on the fabrication methods, characteristics, and applications of the functional liquid metal materials. Furthermore, the future outlook in this field, including challenges, routes, and related efforts, has also been illustrated and interpreted.

     

Surface Tension Measurements of Liquid Metals by the Quasi-Containerless Pendant Drop Method

The surface tensions of liquid metals, Zr, Ni, Ti, Mo, and Nb, have been measured at their melting points using the quasi-containerless pendant drop method. This method involves melting the end of a high-purity metal rod by bombardment with an electron beam to form a pendant drop under ultrahigh-vacuum conditions to minimize surface contamination. The magnified image of the drop is captured from a high-resolution CCD camera and digitized using a frame-grabber. The digital image is analyzed by reading the pixel intensities from a graphics file. The edge coordinates of the drop along rows and columns of pixels are searched by a computer program and stored in an array. An optimized theoretical drop shape is computed from the edge coordinates by solving the Young–Laplace differential equation to deduce the surface tension. The measured surface tensions are compared with available experimental results and theoretical calculations.     

On‐Chip Production of Size‐Controllable Liquid Metal Microdroplets Using Acoustic Waves

Micro‐ to nanosized droplets of liquid metals, such as eutectic gallium indium (EGaIn) and Galinstan, have been used for developing a variety of applications in flexible electronics, sensors, catalysts, and drug delivery systems. Currently used methods for producing micro‐ to nanosized droplets of such liquid metals possess one or several drawbacks, including the lack in ability to control the size of the produced droplets, mass produce droplets, produce smaller droplet sizes, and miniaturize the system. Here, a novel method is introduced using acoustic wave‐induced forces for on‐chip production of EGaIn liquid‐metal microdroplets with controllable size. The size distribution of liquid metal microdroplets is tuned by controlling the interfacial tension of the metal using either electrochemistry or electrocapillarity in the acoustic field. The developed platform is then used for heavy metal ion detection utilizing the produced liquid metal microdroplets as the working electrode. It is also demonstrated that a significant enhancement of the sensing performance is achieved by introducing acoustic streaming during the electrochemical experiments. The demonstrated technique can be used for developing liquid‐metal‐based systems for a wide range of applications.     

Room‐Temperature Liquid Metal Confined in MXene Paper as a Flexible,Freestanding, and Binder‐Free Anode for Next‐Generation Lithium‐Ion Batteries

Exploring flexible lithium‐ion batteries is required with the ever‐increasing demand for wearable and portable electronic devices. Selecting a flexible conductive substrate accompanying with closely coupled active materials is the key point. Here, a lightweight, flexible, and freestanding MXene/liquid metal paper is fabricated by confining 3 °C GaInSnZn liquid metal in the matrix of MXene paper without any binder or conductive additive. When used as anode for lithium‐ion cells, it can deliver a high discharge capacity of 638.79 mAh g^?1 at 20 mA g^?1. It also exhibits satisfactory rate capacities, with discharge capacities of 507.42, 483.33, 480.22, 452.30, and 404.47 mAh g^?1 at 50, 100, 200, 500, and 1000 mA g^?1, respectively. The cycling performance is obviously improved by slightly reducing the charge–discharge voltage range. The composite paper also has better electrochemical performance than liquid metal coated Cu foil. This study proposes a novel flexible anode by a clever combination of MXene paper and low‐melting point liquid metal, paving the way for next‐generation lithium‐ion batteries.     

液相添加剂对纳米溴化锂溶液表面张力和沸腾温度的影响

通过在纳米溴化锂溶液中添加液相添加剂降低溶液沸腾温度,从而有助于大幅度应用工业余热、废热等低品味热源。溶液沸腾温度主要反映了溶液汽泡成核所需的临界活化能(过热度)。尽管影响沸腾温度的因素较多,但是溶液的表面张力是一个重要的因素。此外纳米流体中的分散剂能造成纳米颗粒在加热面上如淤泥般的沉积,湮没了汽化核心,导致沸腾温度升高。     

High Dielectric Performances of Flexible and Transparent Cellulose Hybrid Films Controlled by Multidimensional Metal Nanostructures

Various wearable electronic devices have been developed for extensive outdoor activities. The key metrics for these wearable devices are high touch sensitivity and good mechanical and thermal stability of the flexible touchscreen panels (TSPs). Their dielectric constants (k) are important for high touch sensitivities. Thus, studies on flexible and transparent cover layers that have high k with outstanding mechanical and thermal reliabilities are essential. Herein, an unconventional approach for forming flexible and transparent cellulose nanofiber (CNF) films is reported. These films are used to embed ultralong metal nanofibers that serve as nanofillers to increase k significantly (above 9.2 with high transmittance of 90%). Also, by controlling the dimensions and aspect ratios of these fillers, the effects of their nanostructures and contents on the optical and dielectric properties of the films have been studied. The length of the nanofibers can be controlled using a stretching method to break the highly aligned, ultralong nanofibers. These nanofiber‐embedded, high‐k films are mechanically and thermally stable, and they have better Young's modulus and tensile strength with lower thermal expansion than commercial transparent plastics. The demonstration of highly sensitive TSPs using high‐k CNF film for smartphones suggests that this film has significant potential for next‐generation, portable electronic devices.