Tinghua Li

Alkaline water electrolysis at high temperatures can rival acidic proton–exchange membranes. However, they suffer from increased energy consumption, reduced lifespan of materials and heightened safety risks. Magnetic hyperthermia is a method of localizing intense heating in the presence of an external high–frequency alternating magnetic field (AMF). In this study, we developed a custom electromagnetic induction device capable of generating a small magnetic field of about 2 µT. High–permeability nickel foam is used as electrodes. Results show that the iron coated nickel foam decreases the overpotential of the hydrogen evolution reaction (HER) and oxygen evolution reaction by ∼150 mV and 60 mV, respectively, at 20 mAcm⁻² when subjected to magnetic heating in a high–frequency AMF. The overall water splitting current of Ni foam/Fe increases 540% under intermittent induction. The enhanced stability of Ni foam/Fe is attributed to the high binding energy of metal–O on the surface. The density function theory calculations further indicates that the lattice expansion of the metal electrode under induction heating optimizes the adsorption and desorption of H*, thereby enhancing the HER performance.

The controlled release of volatile compounds is one of the important research topics in the field of food. In order to improve the flavor release ability of menthol and to achieve a temperature‐controlled release of menthol, chitosan (CS) and polycaprolactone (PCL) are used as raw materials to prepare nanofibrous membranes by electrostatic spinning and menthol‐loaded nanofibrous membranes are subsequently prepared by incorporating a menthol flavor. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), XRD, and solid‐state NMR are applied to characterize the morphology and chemical structure of the nanofibrous membranes. Thermogravimetric analysis (TGA) is used to test the thermal stability and release characteristics of the menthol‐loaded nanofibrous membranes. The gas chromatography (GC) assay shows that the CS/PCL nanofibrous membrane has a menthol loading of 57.64% and can gradually release menthol from 85 to 260°C, thus, achieving a temperature‐controlled release of menthol. A 14‐day stability test shows that the nanofibrous membrane retains menthol up to 40.23% and cytotoxicity experiments confirm their good biocompatibility and biosafety. The method of embedding menthol proposed in this paper can offer the possibility of controlling the temperature to release menthol and providing potential ideas for the application of menthol in food and pharmaceuticals.

Indium tin oxide (ITO) ceramics with different SnO₂ contents were fabricated using the conventional solid-state reaction. The phase structure, microstructure, electrical conductivity, heating, and mechanical properties were investigated in detail. The results showed that pure ITO ceramics with high relative density were obtained successfully. The ITO ceramics were cut into regular rectangles to serve as electrical heaters. Additionally, their saturation temperatures and thermal response times were tested at different voltages. The results showed that ITO ceramics with 10% SnO₂ had the fastest thermal response rate and reached a saturation temperature of 376^∘C at 1.5[ ]V voltage, the highest temperature reported in the literature for In₂O₃ ceramics. Moreover, In₂O₃ with 10% SnO₂ showed good mechanical properties. Hence, ITO ceramics, as electrical heaters with low driving voltage and high response speed, are expected to have potential heating applications such as domestic heating and industrial production.

To solve the problems of electromagnetic heating cigarette devices in heating speed and temperature control accuracy, the optimization of the control system was carried out based on the current device. And the special control system for the electromagnetic heating cigarette device was designed, which was powered by a lithium battery device and designed with a half-bridge push-pull double resonant capacitor. According to the test, the prototype can preheat at 350 °C in 7 seconds at the fastest, with an average rate of 44.33 °C/s; The maximum temperature deviation at the constant temperature stage cannot exceed 5 °C, and the temperature control accuracy can be ± 1.47%; in the simulated suction stage, the prototype can be warmed back from 280 °C to 340 °C in 3 seconds. Compared with the original dual-tube single-capacitor resonant circuit, it has nearly double the heating power. The experimental data shows that the temperature rise rate and temperature control accuracy was significantly improved, giving full play to the performance advantages of electromagnetic heating.

Here, simultaneous extraction and SERS detection of nicotine for rapid and reliable identification of nicotine release of snus products were performed based on nano-Au assembly hierarchy structure in the capillary.

Superhydrophobic and oleophobic surfaces have attracted increasing attention because of their self-cleaning properties. A composite coating composed of anodized titanium and sol-gel (TiAO/SG) was developed and has good superhydrophobic and oleophobic property. The anodized titanium coating was prepared on the titanium substrate and then a sol-gel layer was coated on the surface of the anodized titanium layer to obtain a composite coating with superhydrophobic and oleophobic properties. The adhesion weight of glycerol on the surface of the superhydrophobic titanium wire decreased to 4.8% of that of untreated titanium wire, which showed that the material had good oleophobic property. This new composite coating could achieve self-healing superhydrophobicity by releasing loaded perfluorodenytriethoxysilane to the surface of the coating. Given its superhydrophobicity, self-healing and wear resistance, the TiAO/SG coating was expected to achieve healable self-cleaning protection in titanium devices.

This study proposes a method to drive a solid by liquid–solid coupling and designs and manufactures a surface acoustic wave actuator to drive a wetted solid ball. The solid ball moves under surface acoustic wave microfluidic acoustic streaming. By theoretical analysis and experimental testing, the driving model is systematically examined in terms of the influence of the device frequency, input power, droplet viscosity, and other parameters on the movement of the ball. The speed at the mark end of the ball under 4.17 W of input power and driving at 60-MHz frequency in pure water reaches 0.175 m/s. Compared with the driving method of a surface acoustic wave linear motor, this wetted solid-driven method easily ensures that the solid ball drives to reach the same order of speed, avoiding numerous problems present in the existing surface acoustic wave linear motors. The proposed method provides important guidance and is of practical significance for the application of surface acoustic wave technology in micromotors and micromanipulation.

In this work, a general method is presented for the design of arbitrarily shaped 3D illusion devices with piecewise homogeneous parameters based on geometric divisions and linear coordinate transformations. Three illusion devices that can reshape the sizes or positions of the wrapped objects are demonstrated, namely, shrinking, amplifying, and shifting devices. The shrinking device can shrink a larger object into a smaller one with different material parameters, whereas the amplifying device can enlarge a smaller object into a larger one, and a shifting device can generate a new image with an identical size but located at a different position. In addition, based on the presented shrinking device, a perfect 3D invisibility cloak is achieved by shrinking the wrapped object to sufficiently small dimensions as compared to the operating frequency. An electromagnetic concentrator is also obtained by replacing the coated object of the amplifying device with a compression medium. The presented design approach can be easily extended to the design of other electromagnetic devices and even to other physical fields. It is believed that the presented piecewise homogeneous devices are more practicable in reality and can accelerate the potential applications of illusion devices in both military and commercial fields.

Numerous efficient catalysts have been introduced towards hydrogen evolution to produce H ₂ via water electrolysis. Besides developing highly active catalysts, considerable efforts should be focused on the reaction condition to accelerate electrochemical reactions. Increasing the operating temperature enhances the performances. Here, we demonstrate that a combination of a mature electro-thermal system with the state-of-art water splitting cells can promote hydrogen production efficiency in acid water. In particular, the current density of carbon coated Ag wire increased 12 mA cm ⁻² at elevated temperatures in comparison with room temperature. This heat-induced current increase was six times of Ag wire without carbon coating. The hydrogen evolution improvement is attributed to a better heat distribution in the micro-region between carbon surface and electrolyte. Graphitized carbon in the carbon layer, offers electron transfer pathways, which is beneficial for hydrogen evolution reaction performance; amorphous carbon and layered structure locked electrolyte, stop acid-water flowing and preserves heat.

By performing a two-step coordinate transformation, an N-sided polygonal bifunctional thermal device with nonsingular homogeneous material parameters is proposed based on transformation thermodynamics. The presented device could function as not only a concentrator with heat flux concentration effect, but also an illusion device with a scattering amplification effect. Moreover, to further eliminate the anisotropy of thermal conductivity tensors, multilayer realization of the device through isotropic materials is also investigated. The effectiveness of the design method and the performance of the devices are validated by the full-wave simulations. This work paves a new way for the design of easy-to-implement bifunctional devices and has broad application prospects in such fields as thermal-energy harvesting and thermal camouflage.