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Traditionally, domestic induction heating (IH) is designed to heat the ferromagnetic (FM) pan. However, it is incompetent to heat the non-ferromagnetic (NFM) pan since the small equivalent resistance of the pan will easily result in the overcurrent on the inverter. Inspired by the compensation network in the wireless power transfer (WPT), the series-parallel resonance (SPR) network with a relay switch is newly integrated into the IH technology to develop a dual-resonant topology-reconfigurable inverter for all-metal IH. The proposed system can be purposely configured to a half-bridge series resonant inverter with the pulse width modulation (PWM) to heat the FM pan, or a full-bridge SPR-based inverter with the phase shift control (PSC) to heat the NFM pan, respectively. Moreover, the output-input current gain of the SPR network equals the heating-coil quality factor, thereby readily eliminate the overcurrent issue of the inverter. For exemplification, a 1 kW prototype has been built with system efficiencies of 94.32% and 91.05% for heating FM and NFM pans, respectively. Finally, the proposed system can be evolved to achieve automatic load detection and impedance matching to ensure uninterrupted resonance. Both calculated and measured results are given to validate the flexibility and feasibility of the proposed system.

Strain engineering is a promising method for tuning the electronic properties of two-dimensional (2D) materials, which are capable of sustaining enormous strain thanks to their atomic thinness. However, applying a large and homogeneous strain on these 2D materials, including the typical semiconductor MoS2, remains cumbersome. Here we report on a facile strategy for the fabrication of highly strained MoS2 via chalcogenide substitution reaction (CSR) of MoTe2 with lattice inheritance. The MoS2 resulting from the sulfurized MoTe2 sustains ultra large in-plane strain (approaching its strength limit ~10%) with great homogeneity. Furthermore, the strain can be deterministically and continuously tuned to ~1.5% by simply varying the processing temperature. Thanks to the fine control of our CSR process, we demonstrate a heterostructure of strained MoS2/MoTe2 with abrupt interface. Finally, we verify that such a large strain potentially allows the modulation of MoS2 bandgap over an ultra-broad range (~1 eV). Our controllable CSR strategy paves the way for the fabrication of highly strained 2D materials for applications in devices.

A novel self-centering circular concrete-filled steel tubular (CFST) column to steel beam connection is developed. The connection has a beam web friction device (WFD) that provides energy dissipation and post-tensioned (PT) high-strength steel strands running parallel to the beam. The PT strands provide self-centering behavior to the connection. The mechanical behavior of the connection was analyzed theoretically. Three full-scale specimens were tested to investigate the mechanical characteristics of the connections under low-cyclic reversed loading. And the effects of the parameters including the initial posttensioning force, the pretension force in the friction bolts though WFD and the number of PT strands on the performance of the connection were examined experimentally and numerically. Both the experiment and simulation results show that the self-centering capacity increased with the increase of initial PT force or the number of PT strands, however, decreased with an increase in the pretension force in the friction bolts; while the energy dissipation increased with an increase in the pretension force in the friction bolts. The beam and column remained elastic under 5% inter-story drift; the PT strands and WFD can provide excellent self-centering and reasonable energy dissipating capacities for the connection, respectively.

Perovskite/silicon tandem solar cells (PSTSCs) have exhibited huge technological potential for breaking the Shockley-Queisser limit of single-junction solar cells. The efficiency of P-I-N type PSTSCs has surpassed the single-junction limit, while the performance of N-I-P type PSTSCs is far below the theoretical value. Here, we developed a composite electron transport layer for N-I-P type monolithic PSTSCs with enhanced open-circuit voltage (VOC) and power conversion efficiency (PCE). Lithium chloride (LiCl) was added into the tin oxide (SnO2) precursor solution, which simultaneously passivated the defects and increased the electron injection driving force at the electron transfer layer (ETL)/perovskite interface. Eventually, we achieved monolithic PSTSCs with an efficiency of 25.42% and VOC of 1.92 V, which is the highest PCE and VOC in N-I-P type perovskite/Si tandem devices. This work on interface engineering for improving the PCE of monolithic PSTSCs may bring a new hot point about perovskite-based tandem devices.

Fiber-based stretchable electronics with feasibility of weaving into textiles and advantages of light-weight, long-term stability, conformability and easy integration are highly desirable for wearable electronics to realize personalized medicine, artificial intelligence and human health monitoring. Herein, a fiber strain sensor is developed based on the Ti3C2Tx MXene wrapped by poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) polymer nanofibers prepared via electrostatic spinning. Owing to the good conductivity of Ti3C2Tx and unique 3D reticular structure with wave shape, the resistance of Ti3C2Tx@P(VDF-TrFE) polymer nanofibers changes under external force, thus providing remarkable strain inducted sensing performance. As-fabricated sensor exhibits high gauge factor (GF) of 108.8 in range of 45–66% strain, rapid response of 19 ms, and outstanding durability over 1600 stretching/releasing cycles. The strain sensor is able to monitor vigorous human motions (finger or wrist bending) and subtle physiological signals (blinking, pulse or voice recognition) in real-time. Moreover, a data glove is designed to connect different gestures and expressions to form an intelligent gesture-expression control system, further confirming the practicability of our Ti3C2Tx@P(VDF-TrFE) strain sensors in multifunctional wearable electronic devices.

MXenes with unique 2D open structure, large surface-area-to-volume ratios, high pseudo-capacitance, and conductivity are attractive for advanced supercapacitor electrodes. However, the restacking issue of MXenes hinders ion accessibility, resulting in the reduction of volume performance, mass load, and speed capability. To address these issues, a facile hydrothermal synthesis strategy is proposed to fabricate Co3O4 nanoparticles-MXene (Co-MXene) composite by the self-assembly process. Co3O4 nanoparticles, introduced in the MXene matrix, effectively prevent self-restacking and shorten ion/electron transport paths. Consequently, the obtained Co-MXene electrode delivers the high-performance of 1081F g−1 at a current density of 0.5 A g−1, surpassing the pristine MXene electrode (89F g−1 at 0.5 A g−1). Being assembled into asymmetric supercapacitors (ASC), a high energy density of 26.06 Wh kg−1 at 700 W kg−1 was realized. After 8000 cycles, the ASC device maintains 83% of initial specific capacitance at 2 A g−1. This work highlights a simple and efficient method for developing high-performance MXene-based electrodes for supercapacitors.

We utilize a high-pressure solid-state technique to prepare yttrium hexaboride (YB6) nanowires at very low temperatures of 200–240 °C. The obtained YB6 nanowires are single-crystals grown along [001] direction confirmed by HRTEM and SAED images. From the growth morphology at different time stages and EDS evidence, we proposed that YB6 nanowires are nucleated and grown from the submicron particle clusters. The temperature-dependent magnetization results indicate that YB6 nanostructures undergo a superconducting transition with Tc = 7.8 K, which is higher than that of reported YB6 bulk single-crystals. Furthermore, the YB6 nanostructures reveal a peak effect in superconducting state observed from the magnetic hysteresis loops, approving that YB6 belongs to a type-II superconductor. The lower and upper critical magnetic fields, Hc1 and Hc2, are determined to be 251 Oe and 1104 Oe, respectively.

Knowledge of the mechanical properties of coal seams is important for the coalbed methane extraction. Cleats are widely existing in coal reservoirs and play a significant role in the mechanical properties of coal. In this study, the effect of cleat distribution on strength and failure characteristics of coal under uniaxial compression was investigated using a COMSOL with MATLAB numerical method that can implement the inhomogeneity and the damage of coal. First, the effect of homogeneity index and residual strength coefficient on the mechanical properties of coal was studied and the parameters used in the numerical model were calibrated based on the experimental test. Next, numerical specimens containing cleats of different angle, different quantity, and combination cleats were established based on the representative distribution characteristics of cleats. The results of the simulated compressive experiments show that different cleat distributions result in variations in strength and failure characteristics of inhomogeneous coal specimens. Then, further detailed research on the characteristics of damage, acoustic emission and crack development were carried out to reveal the failure mechanism of coal specimens containing different cleats. Finally, the effect of failure characteristic on strength characteristic of coal specimens was analyzed.

A micro rod machining method which can switch between electrical discharge machining (EDM) and electrochemical machining (ECM) by attaching/detaching a diode to/from a bipolar pulse generator in parallel to the working gap was newly developed using a wire electrode made of tungsten. The problem of the wire electrode wear was eliminated by the use of the wire electrochemical turning (WECT) method in which the tungsten wire electrode is continuously running. The ultra-short bipolar pulse current was generated by the electrostatic induction feeding method where a pulse voltage is coupled to the working gap through a feeding capacitance. The machining characteristics of three types of wire guide; disk-shaped WC guide, laminated wire guide and cylindrical acrylic guide, were studied. The experimental results showed that the cylindrical acrylic guide has the best machining characteristics without the influence of guide wear and with less stray current flowing through the working gap. Using the cylindrical acrylic guide, the influences of the feeding capacitance C1, and the total amplitude of the pulse voltage on the machining characteristics were studied. Finally, a stainless steel SUS 304 micro-rod with a high aspect ratio of 14 was fabricated efficiently by using the EDM and ECM modes for rough and finish machining in sequence with the same setup, pulse generator, and neutral electrolyte.

Structural morphology and surface features of torrefied cornstalk are investigated under the given torrefaction temperatures of 250 °C, 270 °C, or 290 °C and the different atmospheres at Air or N2....

In this paper, the two-dimensional nano-contact problem with the surface effect is systematically investigated based on Chen–Yao’s surface elastic theory. The Fourier integral transform method is adopted to derive the contact stress and displacement fields of a half-space subjected to a normal triangle distribution force. The theoretical result shows that the surface energy density of the indented bulk substrate, as only one additional parameter, serves as an important factor to influence the contact properties in contrast to the classical contact models. The numerical show that only when the ratio of the contact width to the volume surface energy density to the shear modulus is equal, the difference between the theoretical prediction of surface effect and the classical contact solution without surface effect will be significant. This result indicates that when the surface effect is considered and the surface effect parameter is positive, the semi-infinite substrate will harden, which should be helpful for better understanding the size-dependent mechanisms of surface energy density at nanoscale.

The creation of carbon matrices with a high surface area for effective catalytic activity is an urgent task today, especially in the field of electrocatalysis. In this study, microporous carbon (MPS) with a surface area of about 1300 m2 g−1 was produced from raw plant waste (apricot pit shells) by successive thermal carbonation and chemical treatment. The MPS was impregnated with H2PdCl6 and calcined at various temperatures under a H2–Ar flux. The obtained Pd-NP@MPC (nanoparticle size from 1 to 25 nm) catalysts were characterized in detail by XRD, SEM, TEM and BET methods. Electrochemical tests show that the prepared composites exhibit high electrocatalytic activity and remarkable stability over time (over 50 h) for the HER process and overall water splitting performance. The electrodes have very low overpotentials (η) of 95–117 mV for HER in 1 M KOH at a current density of 100 mA cm−2. Furthermore, the Pd-NP@MPC-300 electrode can reach a high current density of 300 mA cm−2 at η merely of 170 mV and shows excellent electrocatalytic stability in prolonged water electrolysis. The relationships between MPC matrix characteristics, Pd NPs size and electrocatalytic properties are discussed in this paper.

3D metal printing process has attracted increasing attention in recent years due to advantages, such as flexibility and rapid prototyping. This study aims to investigate the orientation effect of electropolishing characteristics on different surfaces of 316L stainless steel fabricated by laser powder bed fusion (L-PBF), considering that the rough surface of 3D printed parts is a key factor limiting its applications in the industry. The electropolishing characteristics on the different surfaces corresponding to the building orientation in selective laser melting are studied. Experimental results show that electrolyte temperature has critical importance on the electropolishing, especially for the vertical direction to the layering plane. The finish of electropolished surfaces is affected by the defects generated during L-PBF process. Thus, the electropolished vertical surface has higher surface roughness Sa than the horizontal surface. The X-ray photoelectron spectroscopy spectra show that the electropolished horizontal surface has higher Cr/Fe element ratio than the vertical surface. The electropolished horizontal surface presents higher corrosion resistance than the vertical surface by measuring the anodic polarization curves and fitting the equivalent circuit of experimental electrochemical impedance spectroscopy.

Al–TiO2–C–La2O3 refiners were synthesized by the in-situ exothermic dispersion method using TiO2, C, Al and La2O3 powders as raw materials. Scanning electron microscopy equipped with energy dispersive X-ray spectrometry and X-ray diffraction were used to investigate the microstructures of the Al–TiO2–C–La2O3 refiners. Commercial pure aluminum was refined by the Al–TiO2–C–La2O3 refiners, aimed at investigating refining performance and the resistance to recession. The results show that the Al–TiO2– C–La2O3 refiner with 0.2% La2O3 is composed of α-Al, blocky Al3Ti, dispersive Al2O3 and TiC, which has a better refining effect on commercial pure aluminum than the Al– TiO2–C refiner. The average grain size refined by the above refiner is about 80 μm and it performs better and has a longer refining effect. The grain structure refined by Al–TiO2– C–La2O3 becomes finer within 5 min and remains the same after 120 min, while refined by the Al–TiO2–C refiner the equivalent times are 10 min and 30 min respectively.

The carbon materials as anode electrodes have been widely studied for potassium ion batteries (PIBs). However, the large size of potassium ions prevents their intercalation/deintercalation, resulting in poor storage behaviors. Herein, a novel design of N/S codoped hierarchical carbonaceous fibers (NSHCF) formed from nanosheets self-assembled by catalyzing Aspergillus niger with Sn is reported. The as-prepared NSHCF at 600 °C (NSHCF-600) exhibits a high reversible capacity of 345.4 mAh g−1 at 0.1 A g-1 after 100 cycles and an excellent rate performance of 124.5 mAh g−1 at 2 A g−1. The excellent potassium storage performance can be ascribed to the N/S dual-doping, which enlarges interlayer spacing (0.404 nm) and introduces more defects. The larger interlayer spacing and higher pyridinic N active sites can promote K ions diffusion and storage. In addation, the ex situ transmission electron microscopy reveals the high reversibility of potassiation/depotassiation process and structural stability.

Highlights Unique “Janus” interfacial assemble strategy of 2D MXene nanosheets was proposed firstly. Ternary heterostructure consisting of high capacity transitional metal chalcogenide, high conductive 2D MXene and N rich fungal carbonaceous matrix was achieved for larger radius Na/K ions storages. The highly accessible surfaces and interfaces of the strongly coupled 2D based ternary heterostructures provide superb surficial pseudocapacitive storages for both Na and K ions with low energy barriers was verified. Abstract Combining with the advantages of two-dimensional (2D) nanomaterials, MXenes have shown great potential in next generation rechargeable batteries. Similar with other 2D materials, MXenes generally suffer severe self-agglomeration, low capacity, and unsatisfied durability, particularly for larger sodium/potassium ions, compromising their practical values. In this work, a novel ternary heterostructure self-assembled from transition metal selenides (MSe, M = Cu, Ni, and Co), MXene nanosheets and N-rich carbonaceous nanoribbons (CNRibs) with ultrafast ion transport properties is designed for sluggish sodium-ion (SIB) and potassium-ion (PIB) batteries. Benefiting from the diverse chemical characteristics, the positively charged MSe anchored onto the electronegative hydroxy (–OH) functionalized MXene surfaces through electrostatic adsorption, while the fungal-derived CNRibs bonded with the other side of MXene through amino bridging and hydrogen bonds. This unique MXene-based heterostructure prevents the restacking of 2D materials, increases the intrinsic conductivity, and most importantly, provides ultrafast interfacial ion transport pathways and extra surficial and interfacial storage sites, and thus, boosts the high-rate storage performances in SIB and PIB applications. Both the quantitatively kinetic analysis and the density functional theory (DFT) calculations revealed that the interfacial ion transport is several orders higher than that of the pristine MXenes, which delivered much enhanced Na+ (536.3 mAh g−1@ 0.1 A g−1) and K+ (305.6 mAh g−1@ 1.0 A g−1 ) storage capabilities and excellent long-term cycling stability. Therefore, this work provides new insights into 2D materials engineering and low-cost, but kinetically sluggish post-Li batteries.

Sodium-ion batteries operating at room temperature have emerged as a generation of energy storage devices to replace lithium-ion batteries; however, they are limited by a lack of anode materials wi...

Obtaining ceramics and composites based on cubic tungsten carbide WC1-x requires knowledge of its thermal behavior, which is poorly studied now. The paper presents the results of a thermal analysis of the nanosized WC1-x-based product with the stoichiometry of WC0.72-0.74 synthesized by a plasma dynamic method. Taking into account the known literature data on the structure of WC1-x products, an investigation of synthesized nanoparticles allows us to conclude that WC1-x cannot exist without a crystalline graphite shell and/or an amorphous carbon matrix. Similarly, the destruction of both carbon shells and a matrix leads to either quick oxidation of WC1-x to WO3 when heated in air or the phase transition WC1-x → WC when heated in vacuum. The thermal analysis shows WC1-x is stable up to 550 °C in air and up to 1200 °C in vacuum and argon. The obtained data made it possible to formulate recommendations for preserving WC1-x material in bulk specimens when compacting from the dispersed powder. The preparation of binderless ceramics from the WC1-x-based product by the SPS method seems to be impossible due to carbon diffusion during the sintering process, while the use of WC1-x-based products as a reinforcing additive to a metal (Al) matrix seems to be the only way to preserve this crystalline phase in a bulk form at the present time.

Vanadium-based cathodes for zinc-ion batteries (ZIBs) hold a great promise for next-generation energy storage systems due to their amazing diversity, relatively high capacity and excellent stability. Unfortunately, the specific capacity of current vanadium-based electrodes is intrinsically limited by zinc site density in crystal structures, probably attributing to the ignore of exception energy storage mechanism in cationic insertion/extraction. Herein, a new energy storage mechanism in the vanadium oxide-based ZIB system via cationic conversion reactions was demonstrated for the first time. At the force of electric and weak acid conditions, the oxygen-doped vanadium nitride (O-VN) cathode was firstly electrochemically oxidized into vanadium oxide and vanadium cations via in-situ activation; the cations would be reduced to V2O3 that depositing on the surface of the electrode in the discharge process; and subsequently the V (III) species could be oxidized back to the cations dissolving into electrolyte upon charging. First-principle density functional theory (DFT) calculations confirm the reversible characteristics of these reactions. Owing to these cationic conversion reactions together with contributions from zinc ion de/intercalation, the O-doped VN cathode delivered an ultrahigh discharge capacity of 705 mAh g−1 at 0.2 A g−1. This work continues to develop the energy storage mechanism of vanadium-based cathode and reveals the arrival of a new era for high-capacity ZIBs.

A superconducting interface Interfaces between materials can harbor quantum states that belong to neither of the materials. A classic example is the superconducting interface between two insulating oxides, LaAlO 3 and SrTiO 3 , with a critical temperature of around 200 millikelvin. Liu et al. observed superconductivity at a different interface—formed between KTaO 3 as a substrate and an overlayer of either EuO or LaAlO 3 —at a considerably higher temperature of about 2 kelvin. Transport measurements displayed anisotropy, which may indicate an unusual superconducting state. Science , this issue p. 716

This study investigates the cracking mechanism of an elliptical bipolar linear-shaped charge blasting via theoretical analysis, experimentation, and numerical simulation. The results show that in the shaped charge blasting, due to the effect of the shaped jet in the direction of the shaped energy, a certain initial crack length is formed. In the action phase of the stress wave, the energy accumulation direction reduces the load required for crack initiation and propagation. The crack propagation length generated in the energy accumulation direction is greater than the nonenergy accumulation direction. The load value of the initial shock wave in the shaped energy direction is significantly greater, by about 1.64 times than the nonshaped energy direction, and the peak load acting time is earlier than the nonshaped energy direction. A large amount of impact explosion energy is consumed in the area close to the charged energy explosion due to the crushing area, regardless of the charged or noncharged energy direction. In the energy accumulation direction, the shock wave attenuation rate is faster in the near explosion area and the stress wave attenuation rate is slower in the mid and far areas of the explosion. The difference in the explosion load in the mid and far areas is small. In the nonconcentrated direction, owing to the reflected compression wave, the second stress peak appears in the nonconcentrated direction. However, its value is smaller than that of the initial shock wave peak.

This article proposes and implements a wireless power transfer (WPT) with series-capacitor-inductor-capacitor (S-CLC) compensation network and pulse-frequency-modulation (PFM) control for dimmable low-pressure sodium (LPS) lamps. Considering the high-voltage ignition and long-time operation, the LPS lamp has the risk of causing electrocution, especially when operating in a humid environment. Thus, the wireless lighting is highly desirable since the LPS lamp can be completely isolated with maintenance-free under all-weather conditions. The proposed S-CLC compensation for WPT can directly drive the LPS lamp without utilizing any magnetic or electronic ballasts. In addition, the PFM control can achieve effective dimming control, reduced operating frequency, and zero-voltage switching (ZVS) concurrently. Theoretical calculations and experimental results are given to validate the feasibility of the proposed wireless lighting system.

As a typical family of two-dimensional (2D) materials, MXenes present physiochemical properties and potential for use in energy storage applications. However, MXenes suffer some of the inherent dis...

Current tumor immunotherapy has excellent application prospects compared with traditional radiotherapy and chemotherapy, but there are still limitations, such as considerable side effects. This problem can be partially solved by treating the local tumor to induce antitumor immunity. In our study, a novel organic photosensitizer Y8 was used to synthesize nanoparticles (Y8 NPs) via a simple nanoprecipitation method. Further investigation indicated the practical photodynamic and photothermal effects of Y8 NPs with 808 nm laser irradiation. Because of its long-wavelength absorption, Y8 NPs also have excellent imaging effects near-infrared-II region. In metastatic tumor-bearing murine models, Y8 NPs can effectively induce phototherapy, suppressing the growth of both primary and metastatic tumors without apparent systemic toxicity through local photodynamic and photothermal therapy synergistic enhancement of antitumor immunity. This study offers a promising therapeutic strategy for synergetic phototherapy and immunotherapy in tumor treatment.

Developing high-efficiency non-precious electrocatalysts for alkaline hydrogen evolution reaction (HER) is critical for practical application in water splitting. Abundant HER electrocatalysts exhibit high activity in acids, but deliver inferior performance in alkalis due to sluggish kinetics. Herein, motivated by the promoter CeO2 (rich in oxygen vacancies) that can modulate the electronic structure of materials, a high-efficiency catalyst of Co4N nanowires by coupling CeO2 vertically grown on Ni foam (Co4N–CeO2/NF) is prepared by composition control and interface engineering. Anchoring CeO2 into Co4N will endow the catalyst with superhydrophilic and superaerophobic properties, and simultaneously promote water adsorption/dissociation, which dramatically boost the alkaline HER performance. The as-synthesized self-supported Co4N–CeO2/NF electrode exhibits fairly low overpotentials of 52 and 149 mV at current densities of 10 and 100 mA cm−2 for HER in 1.0 M KOH electrolyte, respectively. Furthermore, after a long-time operation of 24 h at a fixed high current density of 100 mA cm−2, the required overpotential is increased only by 4 mV, showing the extraordinary long-time durability and promising potential in mass applications. This work will provide an effective strategy for rational design and activity enhancement of other non-precious metal-based HER electrocatalysts.

Injection moulding is ubiquitous in the production of plastic optical components, the functionality of which depends on minimising residual stress and on precisely replicating surface forms. In this study, variotherm-assisted microinjection moulding is used to manufacture a practical microlens array designed for light-field applications in order to achieve satisfactory geometric accuracy, surface quality and stress birefringence of the microlenses, all of which are difficult to achieve by conventional microinjection moulding. Based on in-line process monitoring and a comprehensive evaluation regarding the quantitative and qualitative aspects of the aforementioned factors, the replication is shown to correlate well with machine settings and dynamic machine responses. Screw movements are found to be crucial in the replication process. Compared to an optimised conventional microinjection moulding condition, the general residual stress level and uniformity of the microlens array area are improved by 5.08% and 88.11%, respectively, when the warm circuit temperature is 135 °C and enhanced by 2.73% and 84.32%, respectively, by a delayed switch from the warm circuit to the cold circuit. It is concluded that variotherm-assisted microinjection moulding can significantly reduce residual stresses while maintaining excellent geometric accuracy and surface quality.

Doping with metal ions can improve the electrochemical performance of Na3V2(PO4)3 (NVP) as a cathode material for SIBs. Herein, Na3+xV2−xMIIx(PO4)3/C composites with low Co- and Cu-doping contents (x – 0, 0.01, 0.03, 0.05) have been fabricated by a facile sol–gel method. XRD, ICP-AES and XPS studies show that doping with Co2+ and Cu2+ does not alter the NVP structure of the material, and cobalt or copper successfully substitute the vanadium in its site. Raman and HRTEM data show the presence of an amorphous carbon coating on the phosphate surface, which increases the electronic conductivity of composites. Impedance spectroscopy suggests that low-level doping has significantly increased the electrical conductivity of the NVP matrix. Among all the samples of the compound, Na3.01V1.99Co0.01(PO4)3/C (capacity of 116 mA h g−1 at 0.5C) and Na3.03V1.97Cu0.03(PO4)3/C (capacity of 114 mA h g−1 at 0.5C) demonstrate the highest electrochemical ability. Moreover, even cycling at a high rate of 10C, an excellent reversible capacity is maintained at about 80% of the initial values (in the range of 72–89 mA h g−1) after 1000 cycles. The presented work analyzes the advantages of low doping and the nature of the doping metal in relation to the electrochemical properties of the NASICON-type structure, which will facilitate further commercialization of SIBs.

The wireless power transfer (WPT) for directly driving the high-intensity discharge (HID) lamp is proposed and implemented. In this article, the HID lamp is ignited and operated solely on the resonator without using any ignitor, ballast, or additional LC tank. Meanwhile, the key characteristics in the ignition and running phases are generally analyzed with the consideration of compensation schemes and number of coils. The even-coil series–series (SS) and odd-coil series–parallel (SP) WPT are identified to be more competent for wireless lighting with short and long transfer distances, respectively. In addition, the resonant frequency of 400 kHz is chosen to improve the luminous efficacy up to 150 lm/W. For exemplification, two-coil SS, three-coil SP, four-coil SS, and five-coil SP wireless HID lamps have been built and developed with the overall distances of 20, 40, 68, and 100 cm, and the transfer efficiencies are 94.1%, 89.6%, 83.1%, and 69.2%, respectively. Both the theoretical and experimental results are given to validate the feasibility and flexibility of the proposed system.

All-inorganic CsPbX3 (X = Cl, Br, I, or mixed halides) perovskite quantum dots (QDs) exhibit tunable optical bandgaps and narrow emission peaks, which have received worldwide interest in the field of both photovoltaics (PVs) and light-emitting diodes (LEDs). Herein, it is reported a discovery that CsPbI3 perovskite QD solar cell can simultaneously deliver high PV performance and intense electroluminescence. In specific, the multifunctional CsPbI3 QD film is fabricated through a simple yet efficient solid-state-ligand exchange process using a tailored organic ligand triphenyl phosphite (TPPI). The function of QD surface manipulation using TPPI here is proven to be twofold, balancing the carrier transport and effectively passivating the QD surface to produce conductive and emissive QD film. The CsPbI3 perovskite QD solar cell delivers a champion efficiency of 15.21% with improved open circuit voltage and high fill factor. Concurrently functioning as a red LED, the CsPbI3 perovskite QD solar cell outputs electric power to light conversion efficiency approaching 4%, a record value for QD electroluminescent PVs. The results here indicate that these versatile perovskite QDs may be a promising candidate for fabricating multifunctional optoelectronic devices.

The efficient generation, manipulation and detection of magnetic skyrmions are important for the development of future spintronic devices. One approach is to use electric-current-induced spin torques. Recently, thermally induced skyrmion motion has also been observed, but wider experimental evidence and its capabilities remain limited. Here we report the thermal generation, manipulation and thermoelectric detection of nanoscale skyrmions in microstructured metallic multilayers integrated with on-chip heaters. The local application of heat can facilitate a domain morphological transition and the formation of skyrmions at the device edge, where a low energy barrier exists. We observe the unidirectional diffusion of skyrmions from hot regions to cold regions, which is due to the interplay among the repulsive forces between skyrmions, thermal spin–orbit torques, entropic forces and magnonic spin torques. The thermally generated skyrmions can also be electrically detected via the Nernst voltage. Nanoscale magnetic skyrmions that are generated in metallic multilayers using on-chip heating diffuse from hot to cold regions and can be thermoelectrically detected via the Nernst voltage.

Since the environmental and safety issues closely related to the widely used mixture electrolytes of H2SO4 and H3PO4 in electropolishing 316 L stainless steel, the development of new electrolytes, which do not contain any acid is of a great demand. This study is to electropolish 316 L stainless steel in a NaCl-based electrolyte, not containing any acid as the conventionally used electrolytes. The electropolishing effect with the NaCl-based electrolyte is compared with the conventional H2SO4-based electrolyte. The experimental results show that the proposed electrolyte can be used for the electropolishing of 316 L stainless steel to obtain a comparable electropolishing effect with the conventional H2SO4-based electrolyte. Moreover, the NaCl-based electrolyte shows a higher material removal rate than the H2SO4-based electrolyte. It is also found that a brown product generated and covered on the anode electrode surface during the electropolishing with the NaCl-based electrolyte. According to the EDS analysis, it mainly contains dissolved metal elements, Cl and Na element from the used electrolyte. Furthermore, the electropolishing effect can be improved by the ethanol addition in the NaCl-based electrolyte due to the reduced influence of the brown product.

The wetting behavior of glass coatings on samarium-cobalt alloys with different roughness at elevated temperatures in air was investigated by a sessile drop method. The wetting properties were analyzed through several parameters, including apparent contact angle, height and diameter of a glass cylinder on the samarium-cobalt alloy, determined by using a high temperature microscope. The morphology evolution of the glass coating was observed by using a scanning electron microscope. The results show that the glass cylinder contracts initially, and then swells followed by wetting and spreading on the samarium-cobalt alloy substrate. This process is explained by the role of air and the increase of capillary number. The dependence of apparent contact angle on surface roughness is related to interface reaction. It is concluded that the surface roughness firstly increases the contact angle, but then promotes wetting due to the wetting transition changing from the Cassie−Baxter state to the Wenzel state in the non-reactive wetting range. The surface roughness hinders the spreading of the glass melt due to the interface reaction between glass and samarium-cobalt alloys in the reactive wetting range.

Via a facile solid reactive method, transparent Ln0.1La0.9GdZr2O7 (Ln = Nd, Yb) ceramics were successfully fabricated for the first time. The highest in-line transmittances of Nd:LaGdZr2O7 and Yb:LaGdZr2O7 ceramics reached 68% and 69%, respectively, at 1100 nm. The microstructure and crystal structure of Ln0.1La0.9GdZr2O7 transparent ceramics were fully investigated, indicating that the solid reactive technique is a good method of industrially fabricating Ln0.1La0.9GdZr2O7 transparent ceramics. The PL spectra demonstrated that Ln0.1La0.9GdZr2O7 ceramics can effectively be excited at 808 nm and 976 nm, which correlates with the widely applied output wavelengths of AlGaAs and InGaAs laser diodes. The luminescence decay curves were also studied, showing that the average fluorescence lifetimes of Nd0.1La0.9GdZr2O7 and Yb0.1La0.9GdZr2O7 transparent ceramics was 355 μs and 663 μs, respectively. Combined with its high temperature resistance and good mechanical strength, Ln0.1La0.9GdZr2O7 (Ln = Nd, Yb) transparent ceramics can have potential applications in Nd/Yb solid-state laser construction.

The novel wire electrochemical turning (WECT) method has been proposed to machine tungsten with neutral electrolyte and bipolar pulse current in the authors’ previous research. The influence of tool wear caused by the bipolar pulse current, which is needed to remove the oxide layer generated on tungsten surface when using a neutral electrolyte, was eliminated by the WECT method because the wire tool electrode was kept being wound during the machining process. In this paper, the influences of the most important process parameters, such as the kind of electrolyte, wire material, wire diameter, rotation speed of the workpiece rod, and frequency of the pulse voltage, were studied to understand the fundamental aspects of the WECT method and improve the machining efficiency of tungsten micro-rods. The experimental results showed that the NaCl electrolyte and the NaNO3 electrolyte had higher machining efficiency and better machining accuracy, respectively. The machining accuracy was improved with the SUS304 stainless steel wire used as tool electrode than the brass wire tool electrode. It was also found that the machining efficiency and accuracy were improved with decreasing the wire diameter and increasing the rotation speed of workpiece because the influence of stray current flowing through the side and end surface of machined micro-rod was reduced. The machinable length of micro-rod peaked at an optimum feed speed of the workpiece, and the optimum speed increased with increasing the frequency of pulse voltage. As a result, a minimum rod diameter of 11 μm was fabricated with a high aspect ratio of 36. Compared with the previous method using a platinum film as tool electrode, the aspect ratio was increased significantly because the influence of tool wear was eliminated.

Due to the increasing attention of low temperature combustion, more precise and convenient low temperature chemical reaction mechanism is needed in the combustion reaction flow modelling. However, ...

This study is focused on punch shape design in tube hydro-piercing processes of SPFC590Y carbon steel tubes. The flow stresses of the carbon steel tubes obtained by tensile tests are used in the finite element simulations of tube hydro-piercing process with software “Deform 3D.” The ductile fracture criterion of Normalized Cockcroft and Latham is used during the FE simulations. The critical damage value for NCL fracture criterion is obtained by comparing simulation results and tensile test results. The effects of various parameters such as punch strokes, internal pressures, etc. on tube deformation and fracture mechanism in hydro-piercing processes are investigated. Hydro-piercing experiments are conducted. The characteristics of the experimentally pierced hole sections are compared with the simulation results to validate the analytical models. The effects of various parameters on the characteristics of pierced hole sections after hydro-piercing processes are discussed numerically and experimentally.

Rock-like materials and Barton’s standard joint curve were used to make filled joint specimens, and the shear characteristics of the filled joints were studied. Discrete element software was used to analyze the failure mechanism during filled joint shearing. Based on the experimental findings, a new theoretical model of joint shear strength was proposed. It was found that joint roughness has a great effect on filled joint shear failure, which is manifested via three different morphologies. The effects of the filler on the shear stress–strain curve are mainly a higher slope in the elastic phase and a lower slope in the plastic phase. The shear failure of the filled joint starts from local small damage of the filling and then progresses to failure of the bonding surface or the filling itself. Based on the proportion of the joint failure surface area to the joint surface area, a new formula for calculating shear strength is proposed.

The current work reports the formation of triangular pyramidal pattern on c-plane sapphire substrate by the sulfuric-acid wet etching process. The corner-up Al2(SO4)3 wet-etching reaction product f...

A high-order compensated wireless power transfer (WPT) system is proposed and implemented for dimmable metal halide (MH) lamps without using any ignitor or ballast. Possessing high ignition voltage and constant current output, the LCC - LC compensated WPT is identified to be more competent for MH lamps as compared with the four basic compensation networks as well as the double-sided LCC compensation networks. Meanwhile, dimming control and power stabilization are achieved by the phase-shift modulation, and the multilayer multitype coil is newly proposed to enhance the tolerance of varying coupling coefficients. For exemplification, a wireless dimmable MH lamp operating at 400 kHz has been designed and prototyped. Particularly, the system can tolerate coil deviation up to 20 cm and dim the lamp down to 30% of standard illuminance with the merit of acoustic resonance free. Both theoretical and experimental results are given to validate the feasibility of the proposed system.

In this study, the effect of the annealing atmosphere (N2–CO and pure N2 atmosphere) on the crystal quality, surface morphology, and surface O content of the annealed AlN buffer layers was studied. The FWHM of the (0002) plane of an XRD rocking curve showed that the screw dislocation density of the as-grown AlN film can be reduced by annealing in both N2–CO and pure N2 atmosphere. The AlN film showed an improvement in crystal quality under pure N2 annealing atmosphere. As annealing the AlN buffer layer improves the crystal quality, surface roughness, and surface O content of the AlN film, it should be well controlled for the subsequent growth of III-nitride layers. The surface oxidation that occurred on the AlN films during annealing in N2–CO atmosphere resulted in an increase in surface O content and surface roughness of the AlN films, which is undesirable for the subsequent growth of III-nitride layers. We observed that the surface O content (in the depth of 2-nm) of all annealed AlN films was reduced in the N2 annealing atmosphere, which could be due to the O outgassing from the AlN surface to the pure N2 annealing atmosphere. The O outgassing of the surface O content in the AlN surface layer was related to the volume of space in the annealing setups. However, a large volume of annealing space under pure N2 gas flow resulted in higher thermal decomposition on the annealing AlN films, leading to pits forming on the annealed AlN surface and a smearing of the original step-terrace structure. Therefore, we found that there is an optimal annealing atmosphere space in maintaining the original surface morphology and achieving low surface O content in the annealed AlN film.

To figure out the effects of aluminum-doped ZnO (AZO) and Ag layers for the transparent electrode vertical (TEV) photoconductive semiconductor switch (PCSS) reported in our previous works, several different structures of high power, new vertical, extrinsic-triggered PCSS were designed and their performances are presented. All the PCSSs were fabricated on the vanadium compensated semi-insulating (VCSI) 4H-SiC substrates. The ON-state performance of all device versions was characterized by a test circuit without load resistor. Among all structures, the version with AZO transparent window, AZO subcontact layer, and silver mirror reflector has been testified to be the most reasonable structure, and shows the best results as well. Its minimum ON-state resistance is $6.11~\Omega $ at the optical power density of 2.62 MW/cm2. The factor for the best ON-state performance of this structure is attributed to the improvement of utilization efficiency of laser energy, and good contact between the AZO and SiC substrate.

To incorporate spintronics functionalities into two-dimensional devices, it is strongly desired to get two-dimensional electron gases (2DEGs) with high spin polarization. Unfortunately, the magnetic characteristics of the typical 2DEG at the LaAlO

Laboratory-scale slag-steel equilibrium experiments as well as thermodynamic analyses and industrial tests were performed for 18 pct Cr-8 pct Ni stainless steel to study the effect of slag composition on non-metallic inclusion plasticity and steel cleanliness. First, the results showed that saturated MgO should be added in refining top slag, in particular for low-basicity slag, to avoid heavy corrosion of the refractory lining. Further, the content of MgO + Al2O3 increased and MnO content decreased in inclusions with an increase in the slag basicity; thus, the plasticity of inclusions decreased correspondingly. Conversely, higher-basicity slag was favorable for reducing the total oxygen (T.O.), while the content of dissolved aluminum (Als) in steel increased. On the basis of experimental results and thermodynamic analyses, it was concluded that comprehensive favorable inclusion plasticity and relatively high steel cleanliness could be achieved for slag basicity (CaO/SiO2) in the range of 1.4 to 1.8 and Als lower than 10 ppm. This was verified by industrial test results.

In this study, an eco-friendly electrolyte for electropolishing tungsten and the minimum material removal depth on the electropolished tungsten surface are investigated using an electrochemical etching method. Using a concentrated acid electrolyte, the polarization curve and current density transient are observed. For a NaOH electrolyte, the effects of interelectrode gap and electrolyte concentration on electropolishing are investigated. The differences in electropolishing characteristics are compared among different electrolyte types. Microholes are etched on the electropolished tungsten surface to determine the minimum material removal depth on the tungsten surface. Experimental results indicate the color effect due to a change in the thickness of the oxide film on the tungsten surface after electropolishing with a concentrated acid electrolyte. The surface roughness decreases with the interelectrode gap width owing to the increased current density when using the NaOH electrolyte. However, the electropolishing effect is less prominent with a significantly smaller gap because the generated bubbles are unable to escape from the narrow working gap in time. A material removal depth of less than 10 nm is achieved on the tungsten surface in an area of diameter 300 µm, using the electrochemical etching method.

In order to avoid the loss caused by sudden power failure or loss, UPS is very necessary.As the core part of UPS, the efficiency of DC-DC converter improvement has been a long-term research direction in the industry.Switch tube loss are the main factors influencing the DCDC converter efficiency, SI power component is affected by its material, its performance is difficult to further improve, seriously affect the efficiency of the DC-DC converter, SiC semiconductor with high band gap width, the advantages of high heat conductivity and high electric breakdown strength in recent years become a hot research direction at home and abroad, and silicon carbide material improves the device the possibility of high frequency, miniaturization and efficiency.Compared with Si power devices, the advantages of SiC power devices are higher voltage and temperature resistance, higher operating frequency and lower switching losses.

In the present study, a novel AgOx/BiPO4 sensor was successfully prepared and used for detecting trans-resveratrol. Prepared samples were characterized using methods including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy. The results demonstrate that the AgOx/BiPO4 is composed of AgO, Ag2O, and BiPO4. In addition, a cyclic voltammetry method was used to measure resveratrol concentration using the electrochemical sensor based on AgOx/BiPO4. AgOx/BiPO4 presents a well-defined voltammetric peak at approximately +460 mV versus Ag/AgCl in phosphate-buffered saline solution. In addition, the sensor exhibits a detection limit of 1.0×10−7 M, and the wide dynamic concentration ranges from 2.0×10−7 to 12.5×10−6 M. Stability and interference tests were performed for 20 days. A possible mechanism for AgOx/BiPO4 detection of trans-resveratrol detection is proposed.