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Hydrogen evolution reaction (HER) catalytic electrodes under actual working conditions show interesting mass transfer behaviors at solid (electrode)/liquid (electrolyte)/gas (hydrogen) three-phase interfaces. These behaviors are essential for forming a continuous and effective physical contact region between the electrolyte and the electrode and require further detailed understanding. Here, a case study on 1T-2H phase molybdenum disulfide (MoS2)/carbon fiber paper (CFP) catalytic electrodes is performed. Rapid gas-liquid mass transfer at the interface for enhancing the working area stability and capillarity for increasing the electrode working area is found. The real scenario, wherein the energy utilization efficiency of the as-prepared non-noble metal catalytic electrode exceeds that of the noble metal catalytic electrode, is disclosed. Specifically, a fluid dynamics model is developed to investigate the behavior mechanism of hydrogen bubbles from generation to desorption on the catalytic electrode surface with different hydrophilic and hydrophobic properties. These new insights and theoretical evidence on the non-negligible three-phase interface behaviors will identify opportunities and motivate future research in high-efficiency, stability, and low-cost HER catalytic electrode development.

Plasma gasification is a novel gasification technology that offers a promising treatment of kitchen waste (KW) and other types of waste (e.g., medical waste). By considering the dried flour and dried rice, a high power (∼35 kW) plasma gasification system for these two raw materials was achieved in this work. Then, the effects of particle sizes and plasma energy ratio (PER, the ratio of plasma energy and the low heat value of the feedstocks) for the dried rice are investigated and discussed. The particles size (

Objectives Platelet-rich fibrin (PRF) has been utilized in regenerative medicine as a concentration of autologous platelets and growth factors that stimulates tissue regeneration. More recently, liquid-PRF (also called injectable-PRF; i-PRF) has been brought to market utilizing PET plastic tubes. Due to new advances made in tube technology, the first aim of the present study was to investigate the liquid consistency of liquid-PRF utilizing both standard and chemically modified PET plastic tubes. Furthermore, it is well known that the conversion of PRF into a fibrin matrix is derived from the temperature-controlled enzymatic process that converts liquid fibrinogen and thrombin to solid fibrin. This study also investigated for the first time the use of a cooling device (Bio-Cool) to extend the liquid working properties of liquid-PRF. Materials and methods In total, 30 participants enrolled in this study. From each patient, four tubes of liquid-PRF were drawn, two standard white Vacuette tubes and two blue chemically modified hydrophobic tubes. Following centrifugation at 700 RCF-max for 8 min in a Bio-PRF horizontal centrifuge, one white and one blue tube were kept upright at room temperature, while the other white and blue tube were placed within the cooling device. Thereafter, the liquid-PRF layers were monitored over time until clotting occurred. Patient gender, age, and altitude above sea level (+ 5000 ft) were recorded and compared for clotting times. Results The findings from the present study demonstrated that the chemically modified PET tubes performed 37% better than the control tubes (extended the working properties of liquid-PRF by over 20 min). Most surprisingly, tubes kept in the cooling device demonstrated an average of 90 min greater working time (270% improvement). While patients living at altitude did significantly improve the clotting ability of liquid-PRF, no differences were observed when comparing male vs female or younger vs older patients in liquid-PRF clotting times. Conclusions Cooling of blood following centrifugation represented a 270% improvement in working properties of liquid-PRF. Optimization of liquid-PRF tubes utilizing chemically modified hydrophobic PET tubes also delayed the clotting process by 37%. Patient gender and age had little relevance on liquid-PRF. Clinical relevance The present findings demonstrate for the first time that cooling of liquid-PRF is able to extend the working properties of liquid-PRF by over 90 min. Thus for clinicians performing longer clinical procedures, the cooling of blood may represent a viable strategy to improve the working time of liquid-PRF in clinical practice.

Microwave-assisted catalytic technology is potentially promising in the application of water treatment due to its merits of high reaction rates, simple equipment and operations. In case of the cartap wastewater rarely studied, the easy transformation of cartap into metabolites could induce higher toxicity. This study aimed to develop a novel catalyst Ce/Co/γ-Al2O3 to dispose cartap effectively. The catalyst was prepared by loading Ce and Co on the surface of the support Al2O3, followed by characterization with X-ray diffraction, scanning and transmission electron microscopies. Based on the treatment results, the microwave-induced catalytic oxidation procedure over Ce/Co/γ-Al2O3 could decompose the contaminants efficiently and fast in the case of a low oxidant dosage and a wide pH range. Under the conditions of pH of 5, microwave power of 450 W, catalyst dosage of 0.7 g and hydrogen peroxide dosage of 0.2 mL, the activity of Ce/Co/γ-Al2O3 catalyst could reach up to 86.08%. Importantly, the Ce/Co/γ-Al2O3 catalyst displayed excellent stability after using for 6 times in the degradation process. This work paved a new way for the effective catalyst design for efficient microwave-induced oxidative degradation.

Fabricating highly homogeneous plasmonic nanostructures over a large area and optically evaluating their structural quality are challenging. Here, we propose an elegant approach to achieve various ...

The AC losses of high-temperature superconducting (HTS) coils have a large impact on the efficiency of superconducting power devices, so the research on AC losses of HTS coils has become a current hot topic. This paper mainly studied the effects of coil turns, inter-turn spacing, and coil radius of the same superconducting coil structure on its magnetization loss in the external alternating magnetic field environment. Using the finite element simulation software, the two-dimensional axisymmetric model of single-pancake coil with double-tape winding is built. Under the condition of external alternating magnetic field with the same frequency and amplitude, the three structural parameters of superconducting coil are changed, respectively, to calculate the magnetization loss under different conditions. The simulation results are also analyzed theoretically to clarify the main reasons for the change of magnetization loss of the superconducting coil caused by the three variables. The results show that the magnetization loss of the multi-turn superconducting coil is mainly focused on the hysteresis loss. Within a certain range, the more turns of superconducting coil, the smaller the magnetization loss, while the size of inter-turn spacing, and coil radius are positively correlated with the magnetization loss of HTS coils. The simulation results are consistent with the theoretical analysis, which provides ideas and references for the subsequent study of the magnetization loss of HTS coils.

Transport loss is an integral part of high-temperature superconductor (HTS)-coated conductors (CC)’s loss. In the field of high-speed motor, the frequency of the current carried by HTS CCs used as windings can be up to 1MHz. The dependence of transport loss of HTS CCs on current parameters below 1MHz has been investigated based on the $$\mathbf {H}$$ -formulation model in this paper. It is shown that the transport loss of CCs mainly depends on the loss in HTS components and copper components. There exists a transition frequency, below which the loss in the inner HTS layer accounts for the most significant proportion of total transport loss. Above the transition frequency, the transport loss in the outer copper stabilizer becomes the main component. The current amplitude only affects the magnitude of transport loss but does not affect its change rule. Furthermore, the dependence of transport loss on the current waveform is investigated based on typical winding current waveforms. It is also found that there is a transition frequency. The low-order harmonics of current have a greater impact on the transport loss in the HTS layer below the transition frequency. The obtained results of this paper can provide a reference for the research of high-speed superconducting motor and other superconducting equipment in high-frequency current conditions.

An ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) was blended with spiro-(1,10)-bipyrrolidinium tetrafluoroborate (SBPBF4) salt and propylene carbonate (PC) to obtain a liquid mixture electrolyte system. The thermodynamic properties of the mixture electrolyte with different molar compositions such as viscosity, density, and electrical conductivity were determined at different temperatures. Infrared spectroscopy and density functional theory (DFT) are used to calculate and describe the microscopic interactions in the mixture electrolyte system. Then, the IL-based mixture electrolyte was applied in supercapacitor with active carbon electrodes. The supercapacitor performances of the mixture electrolyte including the electrochemical window, the specific capacitance, and the energy density were tested and reckoned by cyclic voltammetry (CV), electrochemical impedance spectrum (EIS), and galvanostatic charge–discharge (GCD) methods, respectively. The interaction analysis and the electrochemical test results indicate that the appropriate addition of IL is a simple and effective way to improve the electrochemical performance of the electrolyte in supercapacitors.

Vertically oriented graphene (VG) is deposited on a wide range of substrates by plasma-enhanced chemical vapor deposition. Moreover, the growth mode of VG is proven to be bottom-up deposition using isotope labeling. The Raman characteristic features of rhodamine 6G (R6G), an aromatic dye, are acquired using VG as a universal fluorescence quencher. The fluorescence quenching mechanism is likely related to the transfer of energy and photon-excited electrons between dye molecules and VG because not only the fluorescence emission spectrum of R6G greatly overlaps with the UV–vis absorption spectrum of VG, but also the resistance of dye-coated VG decreases under light irradiation. In addition, the Raman features of other aromatic dyes, such as eosin Y, rhodamine B, methylene blue, and gallocyanine, are obtained by the same method.

Multilayer graphene has been employed as a functional material for tuning the emissivity in mid- and long-infrared range, which shows great potential for various applications, such as radiative cooling and thermal camouflage. However, the stability of the multilayer graphene is not sufficient for practical applications yet. Even though it is reported that the integrity of the multilayer graphene is compromised by ion intercalation, the detailed mechanism is rather unclear. Here, a set of ionic liquids is deployed as sources of electronic charges for tuning the emissivity of multilayer graphene. It is found that the emissivity modulator using 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([EMIm]NTf2) as the ionic liquid provides a modulation depth of about 0.52 (i.e., about 21% larger than the best-reported value) while maintaining a reasonable device lifetime. The microscopic structures of the multilayer graphene in an operational and failure modulator are investigated by scanning electron microscopy, Raman spectroscopy, X-ray diffraction. The results indicate that the modulation depth of emissivity is negatively correlated with the initial voltage, which represents the reaction potential between the ionic liquid and graphene. Furthermore, not only the chemical reactivity but also the size of both anion and cation in the ionic liquids play important roles in maintaining stability of the modulator. Therefore, a set of criteria (e.g., low initial voltage and small size of anion and cation) is proposed to select proper ionic liquids for emissivity modulation. This not only sheds light on the underlying physics of the modulator but also promotes its practical applications.

In this work, a series of FeS1-xTex (0 ≤ x ≤ 0.15) single crystals were successfully synthesized by a hydrothermal method for the first time. According to the measurement of in-plane resistivity, Hall effect, and magnetoresistance (MR), we find that the superconducting transition temperature Tc is rapidly suppressed with the increasing Te substitution, and finally the superconductivity disappears when x > 0.05. With the substitution of Te for S, the residual resistivity ρ0 increases while the residual resistivity ratio (RRR) decreases monotonously. Meanwhile, the MR of FeS1-xTex is also reduced by Te doping. All these results reveal that the Te substitution introduces more impurity scattering. In consequence, the non-linear field-dependent of Hall resistivity ρxy at low temperature region is suppressed and a linear behavior is restored upon Te doping. The negative Hall coefficients RH for all the FeS1-xTex samples suggest that the electron-type carrier dominates the electrical conduction. Moreover, the MR of FeS1-xTex obviously follows Kohler’s law, indicating the isotropic scattering rates in the Fermi surface.

The electrochemical CO2 reduction reaction (CO2RR) offers an environmentally benign pathway for renewable energy conversion and further regulation of the environmental CO2 concentration to achieve carbon cycling. However, developing desired electrocatalysts with high CO Faradaic efficiency (FECO) at an ultralow overpotential remains a grand challenge. Herein, we report an effective CO2RR electrocatalyst that features Ag single-atom coordinated with three nitrogen atoms (Ag1-N3) anchored on porous concave N-doped carbon (Ag1-N3/PCNC), which is identified by X-ray absorption spectroscopy. Ag1-N3/PCNC shows a low CO2RR onset potential of -0.24 V, high maximum FECO of 95% at -0.37 V, and high CO partial current density of 7.6 mA cm-2 at -0.55 V, exceeding most of the previous Ag electrocatalysts. The in situ infrared absorption spectra technique proves that Ag1-N3 single-atom sites have sole linear-adsorbed CO and can easily desorb *CO species to achieve the highest CO selectivity in comparison with the corresponding counterparts. This work provides significant inspiration on boosting CO2RR by tuning the active center at an atomic level to achieve a specific absorption with an intermediate.

Multielemental nanoparticles (MENPs) provide the possibility to integrate multiple catalytic functions from different elements into one nanoparticle. However, it is difficult to synthesize Ag-based MENPs with transition metals such as Ni and Fe because of the strong phase segregation between Ag and the other metals. Here, we show that nonmetal element P can help the amalgamation of Ag with other metals. Ag-Ni-Fe-P MENPs are successfully synthesized by a solution-phase chemistry, and they demonstrate excellent bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) catalytic activities (the potential gap of the potential at 10 mA·cm-2 for OER and half-wave potential for ORR is 630 mV). More important, the synergistic effect from the MENPs endows them with even higher ORR or OER activity than the Ag or NiFeP nanoparticles. A rechargeable Zn-air battery is fabricated by using the Ag-Ni-Fe-P MENPs as the air electrode. The battery has an energy efficiency of ∼60% at 10 mA cm-2. Its performance is almost unchanged during a working period of 250 h, surpassing the Pt/C+IrO2-based battery. These results suggest that the rationally designed MENPs can integrate multiple catalytic functions together and achieve a synergistic effect, which can be used as high-performance multifunctional catalysts.

Proton exchange membrane water electrolyzer can sustainably and environmentally friendly produce hydrogen. However, it is hindered by the lack of high-performance anode catalysts for oxygen evolution reaction (OER) in acid electrolyte. Herein, IrCuNi deeply concave nanocubes (IrCuNi DCNCs) are successfully synthesized from the selective etching of the facet of cubic nanoparticles, and they significantly boost the OER. The obtained IrCuNi DCNCs show high activity toward OER in the acidic electrolyte, which only requires an overpotential of 273 mV to achieve the OER current density of 10 mA cm-2 at a low Ir loading of 6.0 μgIr cm-2. The precious metal based mass activity is 6.6 A mgIr-1 at 1.53 V, which is 19 times as high as that of pristine Ir. It demonstrates that the outstanding catalytic performance is beneficial from the well-defined multimetal concave nanostructures, which may shed light on the fabrication of efficient water electrolyzers.

Al–Cr–Fe–Ni dual-phase high entropy alloys (HEAs) were prepared by arc melting, and the microstructure and wear behavior of HEAs were investigated. The results show that HEAs were consisted by face-centered cubic (FCC) phase and body-centered cubic (BCC) phase, which is consistent with the design. As the BCC phase volume fraction increases, the hardness increases from 183 HV (X-10) to 433 HV (X-90), since that the hardness of BCC phase is higher compared with the FCC phase. The average friction coefficient decreases from 0.409 to 0.111 and the wear depth of alloys decrease from 7.629 to 0.973 μm, which inadicate that the wear resistance of Al–Cr–Fe–Ni dual-phase HEAs are improved with the increase in BCC phase volume fraction. The volume fraction of BCC phase is the main factor affecting the wear behavior of alloys.

To improve the strength of single FCC phase Al0.6CrFe2Ni2 high entropy alloy without reducing the plasticity, nano-phase SiC was selected as reinforcement phase. Aseries of as-cast SiC/Al0.6CrFe2Ni...

In this study, a graphene oxide/polyvinylidene fluoride (GO/PVDF) tight hollow fiber membrane (HFM) with improved permeability was fabricated via one-step direct spinning process to fractionate the dyes and salts (NaCl and Na2SO4) in textile wastewater. Scanning electron microscopy (SEM) indicated that the GO/PVDF HFM possessed a smooth and tight outer selective layer and a relatively porous and loose inner surface. The optimized HFM not only possesses a small mean pore radius of 1.14 nm, but also has a high pure water flux of 24.8 L/m2·h·bar. The stronger negative charge (− 40 mV at pH = 7) was obtained by the GO/PVDF HFM. Due to the synergistic effects of size exclusion and charge repulsion, the resultant HFM exhibited excellent rejection for dyes (i.e., close to 100% for Congo red and Methyl blue, 98.9% for Eriochrome black T) and low salts rejection (i.e., 1% for NaCl, 11% for Na2SO4). Besides, with appropriate addition of hydrophilic GO to the doped solution, the resultant membrane exhibited good hydrophilicity, antifouling property and excellent stability. The newly developed tight HFM would be of great significance for effective fractionation and treatment of textile wastewater.

Two-dimensional transition metal disulfides such as MoS2 and WS2 exhibit multiple phases. Altering their phase makes it possible to change their chemical and physical properties significantly. Although several phase-induced modification mechanisms have been reported, their effects on the gas-sensing performance of these substrates remain unknown. Here, the effects of phase selection on the gas-sensing characteristics of 1T' and 2H monolayer MoS2 and WS2 were explored using a density functional theory-based first-principles approach. The theoretical computations took into account the binding energy, band structure, theoretical recovery time, density of states, electron difference density, and total electron density. The results showed that there is a significant change in the density of states near the Fermi level as well as greater charge transfer between the gas in question and the substrate when the gas is adsorbed onto 1T' MoS2 and WS2. Thus, phase selection is important for improving the gas-sensing performance of monolayer MoS2 and WS2. This study provides theoretical evidence for increasing the sensing performance of polymorph films of these materials.

In this study, we fabricated an Al-doped ZnO/intrinsic ZnO (AZO/i-ZnO) bilayer film using a radio frequency generator coupled with a direct current voltage bias. An 800-nm AZO/50 nm i-ZnO transparent conductive oxide layer with a resistivity of 2.58 × 10-4 Ω cm and a sheet resistance of 3.22 Ω/□ was fabricated using this method. The resistivity of the AZO/i-ZnO layer remained unchanged even after 1 h of Cl treatment at 400 °C. The layer showed an average light transmission rate of 85% over the wavelength range of 400–800 nm. The material, optical, and electric properties of the AZO/i-ZnO layer were investigated. The mechanism underlying the Cl treatment resistance of the AZO/i-ZnO layer was also investigated.

Two-dimensional (2D) material-based anodes facilitate the development of next-generation ion batteries due to their high ion loading capacity and mobility. In this study, using first-principles cal...

Hydrogen is a clean energy with high efficiency, while the storage and transport problems still prevent its extensive use. Because of the large specific surface area and unique electronic structure, two-dimensional materials have great potential in hydrogen storage. Particularly, monolayer 2H-WS2 has been proven to be suitable for hydrogen storage. But there are few studies concerning the other two phases of WS2 (1T, 1T′) in hydrogen storage. Here, we carried out first-principle calculations to investigate the hydrogen adsorption behaviors of all the three phases of WS2. Multiple hydrogen adsorption studies also evaluate the hydrogen storage abilities of these materials. Comprehensive analysis results show that the 1T′-WS2 has better hydrogen storage performance than the 2H-WS2, which means phase engineering could be an effective way to improve hydrogen storage performance. This paper provides a reference for the further study of hydrogen storage in two-dimensional materials.

Based on a facile three-step preparation method, Cu2O/Au/TiO2-NAs ternary heterojunction nanocomposites have been successfully synthesized by electrodepositing a Cu2O layer on the surface of Au nanoparticles (NPs) decorated highly ordered TiO2 nanotube arrays (NAs). The structure, surface morphology, chemical composition, and optical and intrinsic defects properties of the as-prepared samples are characterized by transmission and scanning electron microscopy (TEM and SEM), X-ray diffraction (XRD), UV–vis light absorbance spectra, Raman scattering, and X-ray photoelectron spectroscopy (XPS). Simultaneously, the Cu2O/Au/TiO2-NAs ternary nanohybrids exhibited progressively improved photoelectrocatalytic (PEC) performance compared with the dual Cu2O/TiO2-NAs type-II nanoheterojunctions, confirming by the photocurrent density versus testing time curve (amperometric I–t curve), open-circuit potential versus testing time curve (Voc–t curve), and electrochemical impedance spectroscopy (EIS) measurements, which were mainly ascribed to the synergistic effect of reduced interfacial charge transfer resistance and boosted energetic charge carriers generation associated with embedding Au NPs. Furthermore, the self-consistent charge transfer mechanism of Z-scheme and interband transitions mediated with Au NPs for Cu2O/Au/TiO2-NAs triple nanocomposites is proposed, which was evaluated by nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra excited by 266 and 400 nm, respectively. Following this scheme, UV–vis light photocatalytic activities of Cu2O/Au/TiO2-NAs ternary nanohybrids were elaborated toward photodegradation of methyl orange (MO) in aqueous solution, and the photodegradation rate of optimum triple nanocomplex was found to be 90%.

This work addresses the theoretical and experimental investigations of a Love wave based device employing waveguide structure of SiO2/36° YX-LiTaO3 for sensing icing process. The mass loading effect induced by the icing process modulates the acoustic wave propagation, and corresponding changes in device frequency can be collected to evaluate the icing process. The waveguide structure confines the acoustic wave energy into SiO2 thin-film, which contributes well to the improvement of the mass loading sensitivity. The corresponding sensing mechanism was analyzed by solving the acoustic propagation equations in layered structure. The sensing device patterned by delay-line on 36° YX-LiTaO3 substrate with SiO2 guiding layer was photolithographically developed as the sensor element, and characterized by using the high-low temperature chamber. The icing process was simulated by dropping appropriate water on top of the device surface. Very clear and fast frequency response was observed from the proposed sensing device in the icing process, and also, the influence of SiO2 guiding layer thickness on sensor response was also investigated.

The separation behaviour of primary silicon from high-silicon Al-Si melts during the directional solidification under alternating electromagnetic field with varying frequencies and pulling rates is investigated. Results show that the separation of Si from Al-Si melts significantly depends on the electromagnetic frequency and the solidification rate of the melts as well. Moreover, the separation and enrichment effects of Si electromagnetic frequency with 3 kHz was superior to 30 kHz during the electromagnetic separation process, which was independent on the initial concentration. The flat and distinct separation interfaces could be formatted by using a relatively low pulling rate of 5 μm/s and a frequency of 3 kHz. Finally, the differential scanning calorimetry analysis showed that the alloy section had good thermal stability in the whole electromagnetic separation process. This method has the prospect and potential of becoming the method for manufacturing low-cost Al-Si alloys after the electrothermal process.

Surface polarity with different crystal orientations has been demonstrated as a crucial parameter in determining the physical properties and device applications in many transition metal oxide and semiconductor compound systems. The influences of surface polarity on electronic structures in nitrogen-incorporated ZnO lattices have been investigated in the present work. The successful doping of nitrogen atoms in ZnO lattices is suggested by the existence of N-related chemical bonds obtained from X-ray photoelectron spectroscopy analysis where a pronounced N–Zn peak intensity has been observed in the (000\bar 1)-terminated polar ZnO compound compared with the (10\bar 10)-terminated nonpolar ZnO compound. An energy shift of the valence band maximum towards the Fermi level has been resolved for both polar and nonpolar ZnO lattices, whereas a charge redistribution of the O 2phybridized states is only resolved foro-plane ZnO with a polar surface. Angular-dependent X-ray absorption analyses at the OK-edge reveal enhanced surface-state contributions and asymmetric O 2porbital occupations in the (000\bar 1)-terminatedo-plane ZnO compound. The results shed light on the efficient nitrogen doping in ZnO lattices with polar surfaces. The comprehensive electronic structure investigations of correlations between impurity doping and surface polarity in ZnO lattices may also offer guidance for the material design in other transition metal oxide and semiconductor systems.

Hydrogen energy is a high-efficiency and clean energy, but the problem of storage still prevents its extensive use. Large-surface-area, two-dimensional (2D) layered materials have an advantage in hydrogen storage applications. Monolayer MoS2 is a typical 2D material that has been widely studied recently. And the 1T' phase of MoS2 is a focus especially for studies concerning hydrogen. Here, first-principles calculations are carried out to investigate the adsorption behaviors of hydrogen molecules on 1T' MoS2. Comparing with other MoS2-based materials, such as doped or decorated 2H-MoS2, 1T' MoS2 has even better performance in hydrogen adsorption, and its preparation is easier. In multiple hydrogen molecule adsorption, the material shows good stability and appropriate adsorption energy while adsorbing hydrogen molecules. With the researches in this paper, the connection between the adsorption energy and hydrogen mass fraction was set up. This can provide a reference for further studies on hydrogen storage applications.

Rechargeable zinc–air batteries (ZABs) are promising renewable energy storage devices due to their high energy density and preeminent safety. However, they still require highly active and stable oxygen reduction/evolution reaction (ORR/OER) bi-functional catalysts to promote their performance. Here, we report the synthesis of Fe,Ni on N doped carbon sheets supported on N doped carbon nanotubes (Fe,Ni–N–C/N-CNT), which shows ORR activity with a half wave potential of 0.879 V and an OER activity of 315 mV overpotential at a current density of 10 mA cm−2. Using Fe,Ni–N–C/N-CNT as the air electrode, the fabricated primary ZAB shows a high peak power density of 271 mW cm−2, and the rechargeable ZAB can stably operate for more than 200 h with a high energy efficiency of 61%, surpassing the conventional ZABs using Pt/C–IrO2. We find that the ORR activity is related to the Fe–N–C species in the catalysts, while the in situ generated NiFe2O4 nanoparticles under the OER conditions are beneficial for the OER activity. Poly(ethylene imine) used in the synthesis was found to be important for obtaining a high performance catalyst and helps the binding of the carbon sheets containing the Fe–N–C sites to carbon nanotubes and also the capture of the in situ generated NiFe2O4 nanoparticles. These results demonstrated the high potential of functionalized carbon composites for application in rechargeable ZABs.

A complex interplay of different energy scales involving Coulomb repulsion, spin-orbit coupling, and Hund's coupling energy in 2D van der Waals (vdW) material produces a novel emerging physical state. For instance, ferromagnetism in vdW charge transfer insulator CrGeTe_{3} provides a promising platform to simultaneously manipulate the magnetic and electrical properties for potential device implementation using few nanometers thick materials. Here, we show a continuous tuning of magnetic and electrical properties of a CrGeTe_{3} single crystal using pressure. With application of pressure, CrGeTe_{3} transforms from a ferromagnetic insulator with Curie temperature T_{C}∼66 K at ambient condition to a correlated 2D Fermi metal with T_{C} exceeding ∼250 K. Notably, absence of an accompanying structural distortion across the insulator-metal transition (IMT) suggests that the pressure induced modification of electronic ground states is driven by electronic correlation furnishing a rare example of bandwidth-controlled IMT in a vdW material.

With the development of electronic technologies, electronic devices become smaller, while their power density increases dramatically. The resulting excessive heat requires excellent heat dissipation to ensure great performance of the devices. A good thermal interface material (TIM), with excellent bulk thermal conductivity and proper elastic modulus, which can fill the gap between contact surfaces, is of great importance to improve overall performance of thermal management in the electronic devices. Carbon-based materials, such as carbon nanotubes (CNTs) and graphene (Gr), have attracted great attentions, due to their intrinsic high thermal conductivity. In this paper, carbon-based TIMs are reviewed, as well as the thermal conducting mechanisms and techniques to measure thermal properties for materials. The unique three-dimensional network of 3D-Gr provides not only high thermal conductivity, but also excellent mechanical properties, which makes it more competitive as TIM than CNTs and Gr. Furthermore, there is currently no universal characterization techniques, which are suitable to measure thermal properties of all TIMs. Hence, special attention must be paid to select a proper technique based on the measuring principle, in order to obtain accurate results. An outlook of the future challenges of the thermal interface materials is proposed at the end of the paper.

At ambient conditions, potassium dihydrogen phosphate (KDP) usually exists in tetragonal structure, and only transforms to monoclinic structure at a temperature around 503 K. In this study, stable monoclinic KDP is developed at room temperature using a mixture of graphene oxides and unsaturated KDP solution. Furthermore, a reversible phase transition between monoclinic and tetragonal structure is observed by tuning the distance between graphene oxide layers. The first-principles calculation suggests that the tetragonal structure is more energetically favorable when KDP is sandwiched by two graphitic surfaces with a large interlayer distance, whereas the monoclinic structure is more stable with a small interlayer distance. This is attributed to the interaction between ${\mathrm{K}}^{+}$ cations and \ensuremath{\pi} electrons in the graphitic surface, which distorts the local structural configurations. The increase of interaction strength with decreasing interlayer distance not only reduces the crystal-liquid interfacial free energy, which promotes the formation of the monoclinic structure in unsaturated solution, but also stimulates transformation of existing tetragonal KDP to monoclinic structure. The observations shed light on the nucleation mechanism for crystal structure that is usually infeasible and unstable at ambient conditions, and provide an avenue to tune crystal structures for a wide range of metal salts.

Using a YVO4/Nd:YVO4/YVO4 composite crystal end pumped by laser diode, we demonstrate the simultaneously Q-switched and mode-locked self-Raman laser at the firststokes wavelength of 1176.07 nm. Its corresponding linewidth was measured to approximately be 0.14 nm. At the pump power of 38 W and the pulse repetition frequency of 50 kHz, the maximum average output power at 1176 nm was obtained to be 1.34 W with the corresponding optical conversion efficiency of 3.6%. The highest pulse energy and the highest peak power were obtained to be 35 μJ and 10.5 kW, respectively. The shortest mode-locked pulse width of the laser was obtained to be ~300 ps with the corresponding repetition rate of mode-locked laser pulse is ~ 1.11 GHz

Hydrogen-air proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are excellent fuel cells with high limits of energy density. However, the low carbon monoxide (CO) tolerance of the Pt electrode catalyst in hydrogen-air PEMFCs and methanol permanent in DMFCs greatly hindered their extensive use. Applying polybenzimidazole (PBI) membranes can avoid these problems. The high thermal stability allows PBI membranes to work at elevated temperatures when the CO tolerance can be significantly improved; the excellent methanol resistance also makes it suitable for DMFCs. However, the poor proton conductivity of pristine PBI makes it hard to be directly applied in fuel cells. In the past decades, researchers have made great efforts to promote the proton conductivity of PBI membranes, and various effective modification methods have been proposed. To provide engineers and researchers with a basis to further promote the properties of fuel cells with PBI membranes, this paper reviews critical researches on the modification of PBI membranes in both hydrogen-air PEMFCs and DMFCs aiming at promoting the proton conductivity. The modification methods have been classified and the obtained properties have been included. A guide for designing modifications on PBI membranes for high-performance fuel cells is provided.

In this paper, a new TbDyFe thin-film coated Surface Acoustic Wave (SAW) sensor is proposed for sensing current. A 150 MHz SAW device with delay line pattern is fabricated photolithographically on 128° YX LiNbO 3 substrate. Then the TbDyFe thin-film is deposited into the propagation path of surface acoustic wave by magnetron sputtering to build the sensing device. The reference sensing device with TbDyFe thin-film and the naked device are collected in a dual-channel differential oscillator so as to build the current sensor. When the magnetic field excited by the current is applied, the magnetostrictive effect produced by the TbDyFe thin-film causes the change of SAW propagation speed. And then the change of the corresponding oscillator frequency is used to characterize the current. Taking advantage of the TbDyFe thin-film such as high magnetostrictive coefficient and low coercive force, high sensitivity of 16.8 kHz/A is achieved in the experiments.

Reverse electrodialysis (RED) is an emerging membrane-based technology for the production of renewable energy from mixing waters with different salinities. Herein, the impact of the stack configuration on the Ohmic and non-Ohmic resistances as well as the performance of RED were systematically studied by using in situ electrochemical impedance spectroscopy (EIS). Three different parameters (membrane type, number of cell pairs and spacer design) were controlled. The Ohmic and non-Ohmic resistances were evaluated for RED stacks equipped with two types of commercial membranes (Type I and Type II) supplied by Fujifilm Manufacturing Europe B.V: Type I Fuji membranes displayed higher Ohmic and non-Ohmic resistances than Type II membranes, which was mainly attributed to the difference in fixed charge density. The output power of the stack was observed to decrease with the increasing number of cell pairs mainly due to the increase in ionic shortcut currents. With the reduction in spacer thickness from 750 to 200 µm, the permselectivity of membranes in the stack decreased from 0.86 to 0.79 whereas the energy efficiency losses increased from 31% to 49%. Overall, the output of the present study provides a basis for understanding the impact of stack design on internal losses during the scaling-up of RED.

Both high through-plane thermal conductivity and low elastic modulus can reduce thermal interface resistance, which is important for thermal interface materials. The internal porous structure of graphene aerogel (GA) makes it to have a low elastic modulus, which results in its good compressibility. Also, the network structure of GA provides thermal conducting paths, which improve the through-plane thermal conductivity of GA. Annealing GA at 3000 °C helps to remove oxygen-containing functional groups and reduces defects. This greatly improves its crystallinity, which further leads to the improvement of its through-plane thermal conductivity and it has a low modulus of 1.37Mpa. The through-plane thermal conductivity of GA annealed at 3000 °C (GA-3000) was improved as the pressure increased and got to 2.93 W/ m K at a pressure of 1.13 MPa, which is 30 times higher than other graphene-based thermal interface materials (TIMs). These discoveries offer a novel approach for preparing excellent TIMs.

The overprescription and improper use of antibiotics have contributed to the evolution of bacterial resistance, making it urgent to develop alternative therapies and agents with better efficacy as well as less toxicity to combat bacterial infections and keep new resistance from developing. In this work, a novel light-activable nano-antibiotic platform (TC-PCM@GNC-PND) was constructed by the incorporation of gold nanocages (GNC) and two thermosensitive gatekeepers, phase-change materials (PCM) and thermosensitive polymer poly(N-isopropylacrylamide-co-diethylaminoethyl methacrylate) (PND), to realize precisely the synergy of photothermal and antimicrobial drugs. GNC exhibits an excellent photothermal effect owing to its strong absorbance in the near-infrared (NIR) region, and hollow interiors make it a favorable vehicle for loading various antibiotics such as tetracycline (TC). The release of the encapsulated drugs could be precisely controlled by NIR light through the dual thermosensitive interaction of liquid-solid transition of PCM and coil-granule transition of PND, improving efficacy and alleviating side effects with on-demand drug release. The thermosensitive hydrogel was formed in situ upon application with body temperature, enhancing retention of the antimicrobial agent in local infectious sites. Highly effective ablation of bacteria is achieved both in vitro and in periodontitis models with little toxicity owing to the synergy of photothermal effects and chemotherapeutic drug release induced by NIR. This study could provide guidance for the design of antibacterial materials and shed substantial light on synergistic treatment.

High-Tc ACa2Fe4As4F2 (A = K, Rb, and Cs) as novel 12442-type Fe-based superconductor has simulated great interests. The magnetic orders of Fe-based superconductor have been widely analyzed since its superconductivity competes with magnetism. The ground state of KCa2Fe4As4F2 bulk revealed by the first-principle calculation is stripe-type antiferromagnetic (AFM). However, no research on strained KCa2Fe4As4F2 films has been reported so far. Here, the compressive and tensile strain effects on the ground magnetic orders and electronic structures of KCa2Fe4As4F2 film (grown on LaAlO3 and SrTiO3 substrates, respectively) are discussed based on the first-principle calculations. The stripe-type AFM is stable responding to the compressive strain. The magnetic order is changed from stripe-type AFM of the bulk to checkerboard AFM of the tensile-strained film. This magnetism transition can be attributed to the change of density-of-states contribution of Fe-3d states.

Stimuli-responsive membranes exhibit a flexible adjustment in response to environmental stimuli and have been established many applications. In this paper, dual-stimuli-responsive ultrafiltration m...

Metal–organic framework (MOF) membranes exhibit enormous potential for molecular mixtures’ sieving with high permeance, as well as high selectivity. Current MOF composite membranes suffer from unduly thick MOF layer and poor adhesion to the porous support. By a simple multiple seeded growth method, the ultrathin (less than 200 nm) and defect-free MOF layer is prepared on a ZIF-8 in-situ embedded PSf substrate. On the one hand, the nano-sized ZIF-8 crystals embedded on substrate surface act as anchors linking the ZIF-8 layer with the substrate. On the other hand, these ZIF-8 crystals also act as seeds to promote the formation of the ZIF-8 layer and reduce the crystallization time, leading to a thin and continuous ZIF-8 layer. The obtained ultrathin ZIF-8 membrane shows superior gas molecular sieving performance, with a high gas permeance of 24.5 × 10−7 mol/m2/s/Pa for H2 and selectivity of 4.5, 23.2, and 31.5 for H2/CO2, H2/N2, and H2/CH4, respectively. In addition, neither the permeance or the selectivity shows a noticeable change after 3% elongation, which indicates high mechanical integrity of the MOF layer on the ZIF-8 in-situ embedded PSf substrate. We believe that the utilization of MOF in-situ embedded polymer substrate offers a universal and simple strategy strengthening and thinning the MOF layer of its composite membranes.

High-performance electrode materials are one of critical factors that need to be considered for practical applications of supercapacitors with high power density. Herein, nitrogen/oxygen co-enriched amorphous carbon coated graphene with a sandwiched porous architecture was prepared by one-pot hydrothermal synthesis using soy protein as the nitrogen and carbon precursor, followed by carbonization in an argon atmosphere at medium temperatures. To improve the energy storage capability, the as-prepared carbon materials were further thermally oxidized at 350 °C in air. The resultant material demonstrates a high gravimetric (volumetric) specific capacitance of 221 F g−1 (330 F cm−3) at 0.2 A g−1 and 153 F g−1 (229 F cm−3) at 20 A g−1 in 6 M KOH aqueous electrolyte with a high retention rate of ca. 69%.

High efficiency and low heat input are the pursuit of modern welding. In this paper, an innovative high frequency electric cooperated arc welding (HFAW) was developed. The process and joint characteristics of the HFAW were compared with that of traditional arc welding (TAW). In the HFAW, a part of welding heat is generated all over the surface of weld side wall (WSW) directly and rapidly due to the skin effect and proximity effect of high frequency current. The limitation of heat conduction on the TAW was broken through. Benefited from the ultra-speed welding thermal process, the HFAW reaches 3–4 times the welding speed of the TAW, while the heat input needed in the HFAW was only about 60% that in the TAW. Meanwhile, the HFAW joint presented sound weld formation, complete penetration and finer microstructure, which made the joint possess an equal tensile strength with the base metal.

The low cycle fatigue (LCF) properties of Ti-6Al-4V parts fabricated by high-power laser directed energy deposition were investigated. The results show that the parts after solution treatment and aging exhibit superior LCF lives to those of other reported AM Ti-6Al-4V parts, as well as are comparable to those of the wrought counterparts at intermediate strain amplitudes (from 0.8% to 1.1%). Cyclic softening behaviors were found at various strain amplitudes (from 0.65% to 1.7%). In addition, a microstructure-based multistage fatigue model was used to predict their LCF lives and shows good agreement with the experimental data.

Nitrogen-doped porous carbon materials show excellent water adsorption ability by forming strong hydrogen bonding between water molecules and the doped atoms. When these porous carbon materials are used to construct a water management layer (WML) of a passive direct methanol fuel cell (DMFC), high water concentration and hydraulic pressure formed inside the cathode catalyst layer would facilitate the water recovery from cathode to anode. In this paper, a highly hydrophilic nitrogen-doped carbon aerogel was synthesized by the carbonization of hydrogel precursors composed of resorcinol, formaldehyde, and graphene oxide under ammonia, and it was used for the first time to construct the WML for liquid-feed and vapor-feed passive DMFCs. The results show that the WML significantly improves the output performance of the liquid-feed DMFC by enhancing the water recovery, which is characterized and proved by the smaller cathode polarization, the slightly increased anode polarization, and a released cathode water flooding situation. A new method was also proposed to study the in situ methanol crossover of DMFCs, which confirmed that the methanol crossover during the discharge was reduced by the WML. As for the vapor-feed DMFCs, the WML reduces both the cathode and anode polarizations significantly, which increases the output performance greatly. This study opens a new window for the design and optimization of the membrane assembly electrode of DMFCs.

Immune response to implantation materials plays a critical role during early local inflammation and biomaterial-induced regeneration or restoration. A novel platelet concentrate termed i-PRF (injectable platelet-rich fibrin) has recently been developed without any additives by low centrifugation speeds. To date, scientists have investigated the capability of releasing growth factors to improve regeneration but have ignored whether i-PRF can inhibit the inflammatory effect around the wound. The present study investigated the anti-inflammation effects of i-PRF on immune response-related cells, especially macrophages and dendric cells. We found that i-PRF reduced pro-inflammatory M1 phenotype of macrophages and activated dendritic cells around muscle defect that was injected with bacterial suspension. Moreover, in vitro experiments showed similar results. i-PRF deleted inflammatory response caused by lipopolysaccharide to some extent. We determined that TLR4, an activator of inflammatory stimulation and p-p65, a key factor belongs to classical inflammatory related NF-κB signal pathway, can be inhibited by use of i-PRF. Results indicate the potential anti-inflammatory role of i-PRF during regeneration and restoration.

Bubble-like nitrogen-enriched graphitic carbon was prepared using EDTA-Fe(III) sodium complex (ethylenediaminetetraacetic acid ferric sodium salt) as the precursor. The complex was carbonized at 700 °C for 2 h in argon atmosphere, and then, the product was washed with diluted hydrochloric acid and distilled water to remove iron and iron compounds so as to achieve the hollow carbon nanospheres. The as-prepared bubble-like carbon material exhibits excellent energy storage capability as the anode for lithium-ion batteries. A maximal reversible specific capacity of about 505 mAh g−1 can be achieved at a current density of 100 mA g−1, and 150 mAh g−1 can still be retained at a high current density of 1600 mA g−1, demonstrating superior cycling performance and excellent rate capability mainly due to the unique porous architecture and improved conductivity.

Microcapsule of 500 nm was fabricated through non-agitation solution polymerization, used 5, 11, 17, 23-tetra-t-butyl- 25, 26, 27, 28-tetrakis(chlorocarbonyl-methoxy) calix [4] arene (C4C) and piperazine (PIP) with or without agitation. It was the amphiphilic self-assembly of C4C that made microcapsule the unique product for C4C/PIP couple in chloroform. Fourier transform infrared spectrometry (FTIR) and the X-ray photoelectron spectroscopy (XPS) proved the successful preparation of microcapsule. Transmission electron microscope (TEM) showed that microcapsules uniformly scattered in chloroform as a colorless dispersion. Absorption-C4C/PIP ratio curve indicated that the optimum ratio is 1:3 by ultraviolet–visible spectroscopy (UV–Vis). Microcapsule was almost uniform and intact at the optimum concentration of 3 × 10−4 mol L−1 under the optimum ratio of C4C/PIP. TEM and dynamic light scattering (DLS) illustrated that non-agitation solution polymerization is a better method to prepare a dispersion of microcapsules. This dispersion can extract heavy metal cations from their aqueous solution and fixed them over the interface of the two liquid phases through the formation of floccule layer. Inductively coupled plasma optical emission spectroscopy (ICP-OES) data showed that extraction efficiencies of Pb(II), Zn(II), Cu(II), and Ce(II) ions were 98.85%, 100.00%, 99.56%, and 98.97%, respectively. Dilute nitric acid can dissociate floccule layer and release cations into water, meanwhile, renewing the dispersion. The recovery ratio was 77.50%, 62.96%, and 68.42% for Pb(II), Cu(II), and Ce(II) ions, respectively. For Zn(II) ions, the recovery efficiency was more than 99.99%.

Platelet-rich fibrin (PRF) has gained tremendous momentum in recent years as a natural autologous growth factor derived from blood capable of stimulating tissue regeneration. Owing to its widespread use, many companies have commercialized various centrifugation devices with various proposed protocols. The aim of the present study was to compare 3 different commercially available centrifuges at both high and low g-force protocols. PRF was produced on three commercially available centrifuges including the IntraSpin Device (IntraLock), the Duo Quattro (Process for PRF), and Salvin (Salvin Dental). Two separate protocols were tested on each machine including the original leukocyte and platelet-rich fibrin (L-PRF) protocol (~ 700 RCF max (~ 400 RCF clot) for 12 min) as well as the advanced platelet-rich fibrin (A-PRF+) protocol (~ 200 g RCF max (~ 130 g RCF clot) for 8 min). Each of the tested groups was compared for cell numbers, growth factor release, scanning electron microscopy (SEM) for morphological differences, and clot size (both weight and length/width). The present study found that PRF clots produced utilizing the low-speed centrifugation speeds (~ 200 g for 8 min) produce clots that (1) contained a higher concentration of evenly distributed platelets, (2) secreted higher concentrations of growth factors over a 10 day period, and (3) were smaller in size. This was irrespective of the centrifugation device utilized and consistently observed on all 3 devices. The greatest impact was found between the protocols utilized (up to a 200%). Interestingly, it was further revealed that the centrifugation tubes used had a much greater impact on the final size outcome of PRF clots when compared to centrifugation devices. It was found that, in general, the Process for PRF tubes produced significantly greater-sized clots when compared to other commercially available tubes. The Salvin Dental tubes also produced significantly greater PRF clots when compared to the IntraLock tubes on each of the tested centrifugation devices. The present study demonstrated the reproducibility of a scientific concept (reduction in RCF produces PRF clots with more evenly distributed cells and growth factors) utilizing different devices. Furthermore, (and until now overlooked), it was revealed for the first time that the centrifugation tubes are central to the quality production of PRF. Future research investigating tube characteristics thus becomes critically important for the future optimization of PRF. This is the first study to reveal the marked impact of centrifugation tubes on the final production of PRF. Future study thus becomes markedly important to further optimize the quality of PRF-based matrices. It was further found that little variability existed between the centrifugation devices if optimized centrifugation protocols (lower centrifugation speeds) were utilized.