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Photocatalytic fixation of nitrogen to ammonia (NH3) is green but low-efficiency technology due to the high recombination of photo-generated carriers and poor light absorption of photocatalysts. Generally, the adsorption capacity for N2 and the band position of TiO2 are responsible for bandgap, light-adsorption, and the separation of photocarriers. Therefore, they play crucial roles to improve catalytic activity. Herein, N-doping TiO2 hollow microspheres (NTO-0.5) with oxygen vacancies were synthesized via a hydrothermal method using phenolic resin microsphere as a template. The obtained NTO-0.5 achieves an impressive ammonia yield of 80.09 μmol gcat-1 h-1. Oxygen vacancies of NTO-0.5 were confirmed by ESR, Raman, XPS, Zeta potential, and H2O2 treatment for reducing oxygen vacancies. The ammonia yield of NTO-0.5 decreases to 34.78 μmol gcat-1 h-1 after reducing oxygen vacancies by H2O2 treatment, which demonstrates the importance of oxygen vacancies. The oxygen vacancies narrow the bandgap from 3.18 eV to 2.83 eV and impede the recombination of photo-generated carriers. The hollow microspheres structure is conducive to light absorption and utilization. Therefore, the synergistic effect between the oxygen vacancies and the hollow microspheres structure boosts the efficiency of photocatalytic nitrogen fixation. After four cycles, the ammonia production yield still maintains at 76.52 μmol gcat-1 h-1, meaning high stability. This work provides a new insight into the construction of catalysts with oxygen vacancies to enhance photocatalytic nitrogen fixation performance.

InGaN light-emitting diodes (LEDs) grown with an asymmetric multiple quantum well (MQW) are proposed for use in an optical link with an avalanche photodiode (APD) based receiver. In contrast to the high photoresponse of red AlGaInP LEDs in APDs, the proposed blue LEDs provide improved light output and enhanced system bandwidth for directed line-of-sight optical links passing through a 100-cm-long water tank. This improvement is due to the nonuniform carrier distribution within the InGaN MQWs being mitigated by using a thin GaN barrier near the n-GaN to facilitate hole transport capacity. In addition, bandwidth degradation resulting from APD module saturation can also be avoided by using these blue LEDs, successfully establishing a 300 Mbit/s LED-based underwater data link. The proposed InGaN LEDs (zero bias) under illumination exhibit a peak responsivity of 0.133 at λ = 370 nm, an ultraviolet (UV)-to-visible rejection ratio of 4849 and a 3-dB cut-off frequency of 33.3 MHz. Using violet UV laser diodes and the proposed LEDs respectively as the optical transmitter and receiver, an underwater optical link (L = 100 cm) with a data transmission rate of up to 130 Mbit/s and a bit error rate of 4.2 × 10−9 is also demonstrated.

Bio-glycerol Steam reforming over green and economical Co/sepiolite (SEP) catalysts was a promising strategy to hydrogen production. The activation pretreatment of SEP played a vital role for boosting catalytic behavior of Co/SEP. This work originally explored a full activation of SEP by molten NaOH for tailoring the physicochemical properties of Co-based catalysts prepared by urea precipitation method. Differing from the acid pickling/calcination and molten NaNO3 activation, the molten NaOH treatment enhanced surface area of SEP by desilicication/dealumination effect and further improved the exposure of framework Si and its surface ‘reactivity’. According to the characterization results of N2 adsorption-desorption, XRD, TEM, H2-TPR, CO/CO2-TPD and XPS, it was found that the feathered Co-phyllosilicate formed on Co/SEP-NaOH catalyst, which enhanced the metal-support interaction, surface area and basic/metallic sites. In contrast, the molten NaNO3 treatment facilitated the transformation of SEP into loughlinite and it was adverse to metal dispersion. Therefore, Co/SEP-NaOH catalyst possessed the highest conversion (92%) and H2 yield (68%) during the activity test at 600 °C and the superior resistance to amorphous coke. Additionally, DFT analysis was introduced to simulate the process of glycerol adsorption and decomposition and demonstrated the Co–CoO interface as the primary reaction sites for the catalytic process.

Fenton-like catalysts have sparked enormous interest from academic to industrial fields because of their excellent degradability and offered a promising platform for the effective treatment of wastewater. However, it remains a grand challenge to balance their catalytic performance and corrosion resistance for industrial application. To address this issue, we report Cr and C dual-doped photo-enhanced Fenton-like catalysts (Cr, C-FeSiB) in which Cr functions as a corrosion inhibitor to improve recycling performance and C acts as an electron transfer accelerator to raise the cycle efficiency of iron ions during complex Fenton-like reactions. Moreover, we design a low energy-consumption magnetic-suspension-like reactor in which Fenton-like catalysts can work as micro-scaled stirrers to enhance the mass transfer efficiency during the Fenton-like reactions owing to their soft magnetic property.

40Cr is essential to steel for the manufacture of hardened gears, and optimizing its laser quenching process will be of great significance for gear wear and life extension. However, the complete reliance on the experimental trial-and-error approach does not effectively reveal the mechanism of the evolution of the laser quenching process in disk laser. Numerical simulation provides an effective way to obtain the transient evolution of the laser quenching process. In this paper, the temperature changes physical parameters of the quenched material are calculated based on the CALPHAD method. Establish a thermo-elastic–plastic multi-field coupling model for the laser hardening process of the disk laser 40Cr gear steel. Perform the numerical calculations on the transient temperature, martensite phase fraction, and the transformation-induced plasticity stress evolution of the 40Cr laser hardening process. Focus on the mechanism of the mutual coupling between phase change behavior and plastic strain. Calculations show that there is heat accumulation during quenching, with a peak temperature of 1448 K. Plastic stress has a “hump” distribution, with a peak value of 834 MPa, which is 1.25 mm from the center of the focal point. The experimental analyses of the 40Cr gear steel quenching microstructure and hardness distribution state by the Axioskop2 scanning electron microscope, the KEYENCE VH-Z100R super depth of field 3D microscope, and the Q10M microhardness tester reveal the mechanical behavior of the material and the phase hardening law during the quenching process. That provided an essential theoretical basis for effective prediction on quenching residual stress and optimizing industrial production parameters.

In this work, UV light activated multi-cycle photoelectric properties of TiO2 and CdS/TiO2 films in formaldehyde were researched. TiO2 film was prepared by screen printing, CdS/TiO2 compounded film was synthesized by SILAR method. XRD and FE-SEM was used to characterize the TiO2 and CdS/TiO2 samples. Multi-cycle photoelectric properties of TiO2 and CdS/TiO2 with uv light on and off were evaluated by testing the photocurrent. On one hand, under the same bias voltage, CdS/TiO 2showed a higher photocurrent than that by TiO2. The reason for this result should be ascribed to the compounded structure in CdS/TiO2, with which the separation and transfer of photogenerated electron-hole pairs could be improved. On the other hand, with the testing cycle number increased, the photocurrent amplitudes of TiO2 and CdS/TiO2 increased. These results suggested that the time to reach a stable photocurrent value for TiO2 and CdS/TiO2 is much longer than one cycle time (300 S). To illustrate the increased photocurrent amplitude value cycle by cycle, the photocurrent of CdS/TiO2 to a much longer time (more than 4000 seconds) was also tested. To explain these results, corresponding possible illustrations were presented.

As a fullerene derivative, IC70BA is widely used in the ternary organic solar cells (TOSCs) to increase the open circuit voltage (Voc) of the devices. Unfortunately, most of the literature shows that IC70BA will lead to a reduction in the short-circuit current density (Jsc) and fill factor (FF). In this work, IC70BA is added to the PTB7:PC70BM binary system to form the ternary system, which is composed of one donor and two fullerene acceptors. Surprisingly, the addition of IC70BA does not immediately lead to a decrease in Jsc and FF. In fact, the appropriate weight ratio of IC70BA in fullerenes can simultaneously increase the Voc, Jsc, and FF of the TOSCs. The synergistic optimization of the surface and bulk morphology of the ternary active layer suppresses the attenuation of Jsc and FF. The smooth surface and suitable phase separation size effectively guarantee the separation, transport and extraction of the charge. Moreover, the addition of IC70BA can significantly improve the hole transport capacity of the active layer, and the optimal hole mobility is 5.13 – 10”4 cm2V–1S–1. Finally, the TOSCs with 10% weight ratio of IC70BA gives the optimal PCE of 9.24% and ideality factor of 2.3.

For structural bending crashworthiness, previous studies mostly focused on thin-walled tubes with multi-cell cross-sections, while the double-tube configuration was seldom studied. In this paper, the bending crashworthiness of thin-walled tubes with multi-cell and double-tube configurations was compared based on three-point bending tests conducted using the ABAQUS/Explicit code. The numerical results reveal that the reinforcements significantly improve the bending crashworthiness beyond the conventional empty tube according to the two indicators: specific energy absorption (SEA) and crash load efficiency (CLE). For the ratio of cross-sectional width to wall thickness b/t = 100, the double-tube configuration has a similar bending crashworthiness performance to the multi-cell configuration. The asymmetric multi-cell configurations are found to demonstrate more excellent SEA performance than their symmetric counterparts in most cases. For the case b/t = 50, the double-tube configuration significantly prevails over the multi-cell configuration.

Nodular cast iron has the strength and toughness which are close to steel and is widely used in industrial fields. The repair and modification of nodular cast iron based on laser cladding can effectively improve the service life, corrosion resistance, and wear resistance of parts. However, nodular cast iron cladding is prone to cracks and hole defects, severely limiting the promotion and application of this technology. The evolution mechanism of multi-field coupling in the spheroidal graphite cast iron laser cladding is the key to quantitatively reveal the improvement of cladding quality. In this paper, moving Gaussian heat source, the influence of temperature change on material physical parameters, the Marangoni effect of molten pool surface tension, and buoyancy on the molten metal flow were considered. A multifield coupling three-dimensional numerical model of IN625 powder laser cladding on nodular cast iron by disk lasers was established. The calculation reveals the transient evolution law of the cladding temperature field, flow field, and plastic stress field. The microstructure morphologies of the cladding layer were observed by Zeiss sigma HD field emission SEM to verify the effectiveness of the model. The results show that the substrate heat input and heat loss reached equilibrium at 0.8s, and the highest temperature reached 1979.7K. There was apparent Marangoni flow in the molten pool, resulting in a small flow velocity in the center and large edges, and the maximum flow velocity was 0.203m/s. When the molten pool was air-cooled to ambient temperature in 1000s, the maximum residual stress was 429MPa. The micromorphology from the bottom to the top of the molten pool is planar crystals, cell crystals, columnar crystals, and equiaxed crystals, which are consistent with the numerical calculation results.

To avoid and eliminate cracks on the surface of a workpiece, it is very important to quantitatively analyse the temperature field, stress field, and flow field during the laser cladding process. Th...

The fatigue life of the bearing can be predicted effectively by combining the multifield coupling condition of the working process with the internal microstructure. In this paper, a bearing fluid lubrication model is established based on the computational fluid dynamics method, and the calculation result is coupled to the thermal-solid model by the grid mapping method. Through this method, a bearing thermal-fluid-solid multifield coupling dynamics model is established to obtain the evolution information of bearings. Simultaneously, the micro-characterization experiments of SKF6406 bearing (M50 bearing steel) were carried out by electron backscatter diffraction, scanning electron microscope and nano-indentation. The microstructure model of bearing containing micro-inclusions was established by the Voronoi method. On this basis, the microscopic stress distribution characteristics and the motion law of bearing microstructure under the multifield coupling action are solved. In the end, the fatigue life prediction method of rolling bearing was established.

The solution absorption system has great potential for recovery of water and latent heat from industrial gas. However, few investigations have been conducted on the synergistic removal of SO2 and the treatment of the associated precipitation when the method is applied for flue gas from coal-fired power plants. To solve this problem, a falling-film reaction platform was established and the CaCl2 solution was chosen as the liquid desiccant. The effects of solution temperature and concentration, solution pH, O2 content and catalyst concentration on the efficiency of SO2 removal were investigated. The solubility of the CaSO4·2H2O precipitates in the CaCl2 solution was measured. The results revealed that the precipitated component was influenced by the O2 content. The decrease in solution pH was responsible for the decrease in the efficiency of SO2 removal. The highest SO2 removal efficiency of 95.6% was obtained during the operation of solution circulation in this experiment. In addition, the solubility test showed that a higher temperature, a lower concentration and the addition of Ca(OH)2 were conducive to reducing the solubility of the CaSO4·2H2O precipitate in CaCl2 solution.

Paper-based friction materials are porous materials that exhibit anisotropy; they exhibit random pore sizes and quantities during their preparation, thereby rendering the control of their pore structure difficult. Composites with different pore structures are obtained by introducing chemical foaming technology during their preparation to regulate their pore structure and investigate the effect of pore structure on the properties of paper-based friction materials. The results indicate that the skeleton density, total pore area, average pore diameter, and porosity of the materials increase after chemical foaming treatment, showing a more open pore structure. The addition of an organic chemical foaming agent improves the curing degree of the matrix significantly. Consequently, the thermal stability of the materials improves significantly, and the hardness and elastic modulus of the matrix increase by 73.7% and 49.4%, respectively. The dynamic friction coefficient increases and the wear rate is reduced considerably after optimizing the pore structure. The wear rate, in particular, decreases by 47.7% from 2.83 × 10−8 to 1.48 × 10−8 cm3/J as the foaming agent content increases. Most importantly, this study provides an effective method to regulate the pore structure of wet friction materials, which is conducive to achieving the desired tribological properties.

The performances of the organic solar cells (OSCs) largely depends on the selection and preparation of the electron transport layer (ETL). In this paper, the uniform and compact Ge nanoparticles (NPs) film was fabricated by using the plasma enhanced chemical vapor deposition (PECVD) method at room temperature. The Ge NPs film is formed by close packing of amorphous Ge particles with an average diameter of 6.05 nm, and the film shows a fairly smooth surface with a root-mean-square (RMS) roughness of 0.6419 nm. The results shows that Ge NPs film exhibits n-type characteristics, and the longitudinal conductivity of the film is 1.90 × 10−5 S/cm, which is better than that of the ZnO NPs film. The excellent longitudinal charge transport characteristics is attributed to the existence of the columnar structures in the Ge NPs. In addition, the Ge NPs film shows a visible light transmittance comparable to that of the ZnO NPs film. More importantly, the energy levels of the Ge NPs film meets the requirements of the PTB7:PC70BM OSCs for the ETL, and the devices with the Ge NPs ETL shows the power conversion efficiency (PCE) of 7.38%. The characteristic of room temperature preparation make the Ge NPs ETL may become a reliable choice for the flexible devices in the near future.

Short particle residence time directly corresponds to insufficient drying effect of impinging stream reactors. Drying process and particle motion behaviours of dynamic asymmetric impinging stream reactors are investigated in this paper. The relationships of the drying characteristics with the particle residence time are studied, revealing that the high-temperature area of dynamic asymmetric impinging stream reactors varies over time. The particle residence time at T = Tb reaches a maximum value and increases by 94.1% in comparison with that in the symmetric one, and the final particle moisture content reaches zero in the main active area. Reasonably setting initial parameters of fluid and particles and geometric factors can enable the drying process to be completed in the high-temperature area, even in the main active area. For given values of TEp0 and TEm, the relationships of the particle residence time with the drying characteristics are shown in Eqs. (30–32).

In the development of technology to replace chromium and cadmium, WC-12Co powder deposited by an activated combustion high-velocity air-fuel (AC-HVAF) thermal spraying technique is considered an ideal surface protection method to replace surface chromium plating. In this work, the computational fluid dynamics method is used to simulate the AC-HVAF thermal spraying process. A gas-phase model is implemented by using the renormalization group k-e turbulence model. The combustion reaction process is calculated by combining a one-step chemical reaction model and an eddy dissipation model. A discrete phase model of spray particles is established based on the Lagrange method. The changes in gas dynamics, gas component concentrations, and particle flight features during thermal spraying are revealed. The results show that gas-solid coupling can predict particle behavior more accurately. Compared with the propane-fueled gas-phase, the hydrogen-fueled gas-phase has a lower temperature and a higher velocity. Using hydrogen fueling, the particles obtain higher temperature and velocity with increasing reactant mass flow rate and decreasing oxygen/hydrogen ratio. The carrier gas mass flow rate can control the particle temperature but does not change the particle velocity. Higher particle loading reduces particle temperature and increases particle velocity.

The mechanical properties and microstructure of Al-Cu-Li alloy sheets subjected to cryorolling (−100 °C, −190 °C) or hot rolling (400 °C) and subsequent aging at 160 °C for different times were investigated. The dynamic precipitation and dislocation characterizations were examined via transmission electron microscopy and X-ray diffraction. The grain morphologies and the fracture-surface morphologies were studied via optical microscopy and scanning electron microscopy. Samples subjected to cryorolling followed by aging exhibited relatively high dislocation densities and a large number of precipitates compared with hot-rolled samples. The samples cryorolled at −190 °C and then aged for 15 h presented the highest ultimate tensile strength (586 MPa), while the alloy processed via hot rolling followed by 10 h aging exhibited the highest uniform elongation rate (11.5%). The size of precipitates increased with the aging time, which has significant effects on the interaction mechanism between dislocations and precipitates. Bowing is the main interaction method between the deformation-induced dislocations and coarsened precipitates during tensile tests, leading to the decline of the mechanical properties of the alloy during overaging. These interesting findings can provide significant insights into the development of materials possessing both excellent strength and high ductility.

Superconcentrated "water-in-salt" electrolytes have greatly widened the electrochemical stable window (ESW) of aqueous electrolytes, but they also generate new problems, including high costs, high viscosity, and low conductivity. Here we report a 2 m low concentration electrolyte using an N,N-dimethylformamide/water (DMF/H2O) hybrid solvent, which provides a wider ESW (2.89 V) than an aqueous electrolyte (2.66 V) and presents nonflammability, high conductivity, and low viscosity characteristics. In 2 m DMF/H2O hybrid electrolyte, the LUMO energy of the DMF solvent (-0.00931 a.u.) is lower than that of H2O (-0.00735 a.u.), which could effectively promote the degradation of FSI- and lead to stable solid electrolyte interphase formation. As a result, the electrochemical reversibility and cyclability of the KTi2(PO4)3@C (KTP@C) anode in the aqueous electrolyte have been significantly enhanced with the help of DMF addition. Moreover, the K2Zn3(Fe(CN)6)2 (KZnHCF)//KTP@C full potassium-ion battery exhibits highly efficient stability and rate capability with a long cycle performance over 10 000 cycles and delivers a specific discharge capacity of 33 mAh g-1 at a high current density of 20 A g-1. Low concentrations of DMF/H2O hybrid electrolytes can inhibit the hydrogen evolution reaction of aqueous electrolytes, providing more opportunities for the practical application of electrode materials. Not limited to DMF solvent, mixing organic and aqueous solvents will provide more available options and perspectives for improving the energy density and long cycle performance of the aqueous metal-ion battery.

A novel non-keyhole friction stir welding technique was proposed to weld the butt joint of 6061-T6 aluminum alloy with the thickness of 6 mm. A sound joint was obtained by this technique, simultaneously eliminating the flash, shoulder mark and keyhole defects. The sleeve directly affected zone (SDAZ) and the sleeve indirectly affected zone (SIAZ) were divided into the joint according to the plunging position of the hollow sleeve. The lack of root penetration defect was avoided when the plunging depth of the hollow sleeve was only 4.2 mm, because the hollow part inside the sleeve improved the material flow below the sleeve. An S-shaped line was left at the SIAZ, and the height of it had the minimum value of 1.47 mm at 20 mm/min. Whether the failure location of the joint was in SIAZ/SDAZ or the heat-affected zone (HAZ) depended on the height and bonding strength of the S-shaped line. The joint fracture location changed from the SIAZ/SDAZ at 35 mm/min to the HAZ at 20 and 30 mm/min. The maximum tensile strength of 224.3 MPa was obtained at 30 mm/min which was 73.7% of that of the base material. The fracture surface morphology exhibited the typical ductile fracture.

Aqueous supercapacitors (SCs) have attracted more and more attention for their safety, fast charge/discharge capability and ultra-long life. However, the application of aqueous SCs is limited by the low working voltage due to the narrow electrochemical stability window (ESW) of water. Herein, we report a new “water in salt” (WIS) electrolyte by dissolving potassium bis (fluorosulfonyl) amide (KFSI) in water with an ultra-high mass molar concentration of 37 mol/kg. The highly concentrated electrolyte can achieve a wide ESW of 2.8 V. The WIS electrolyte enables a safe carbon-based symmetrical supercapacitor to operate stably at 2.3 V with an ultra-long cycle life and excellent rate performance. The energy density reaches 20.5 Wh/kg at 2300 W/kg, and the capacity retention is 83.5% after 50,000 cycles at a current density of 5 A/g. This new electrolyte will be a promising candidate for future high-voltage aqueous supercapacitors.

At present, the existing thermal interface materials (TIMs) cannot meet the heat dissipation requirements of some high-power density electronic devices. In this study, Bi-based low melting point alloy was made into a thermal conductive sheet to reduce the interface thermal resistance. The thermal conductivity of a thermal conductive sheet was found to be 37.83 W/(m·K), 10 times higher than Dow Corning 5021 thermal grease. In addition, the surface morphology of the Bi-based alloy thermal conductive sheet was changed in this experiment, which was divided into textured and planer type, and the measured interface thermal resistance values lower than Dow Corning 5021 thermal grease by approximately 30% and 27%, respectively. The results prove this Bi-based alloy thermal conductive sheets have the ideal heat dissipation performance and their wide application prospects in high-power density electronic devices.

We experimentally demonstrated a high sensitive gas pressure sensor, which also has more concise processing steps and lower cost. The sensor was fabricated by splicing the single-mode fiber (SMF) and a short section of hollow-core fiber (HCF) which was filled with a Polydimethylsiloxane (PDMS) film to form an enclosed air microcavity with the length of 55 μm. The thin PDMS film also plays a role in reflecting the beam. The thermo-optical effect and the thickness of PDMS film can affect the cavity that is sensitive to external pressure. When the thickness of the PDMS membrane is 3 μm, the measured gas pressure sensitivity reaches to 52.143 nm/Mpa, the linearity is 99.86%, and the cross-sensitivity of the gas pressure over temperature is lower than 2.51 × 10−3 Mpa/°C. Moreover, the compact structure, high sensitivity, high mechanical strength, and convenient fabrication make it suitable for measuring gas pressure in harsh conditions.

The graphene oxide powder (GOP) obtained from the spray drying process often exhibits poor re-dispersibility which is considered due to the partial reduction of GO sheets. The reduction of drying temperature can effectively increase the re-dispersibility of GOP, but result in a decreased drying efficiency. Herein, we found that the re-dispersibility of GOP is strongly affected by its microstructure, which is determined by the feed concentration. With the increase of feed concentration, the GO nanosheet assembly varies from the disordered stacking to relatively oriented assembly, making the morphology of the GOP transform from ball-like (the most crumpled one) to flake-like (the least crumpled one), and the 0.8 mg·ml−1 is the threshold concentration for the morphology, structure, and re-dispersibility change. Once the feed concentration reaches 0.8 mg·ml−1, the appearance of the nematic phase in droplet ensures the relatively oriented assembly of GO sheets to form the layered structure with a low crumpling degree, which greatly improves the polar parts surface tension of the solid GOP, making the GOP easier to form hydrogen bonding with water during the redispersion process, thus stabilizing dispersion. This work provides useful information for understanding the relationships between the morphology, microstructure, and final re-dispersibility of GOPs.

Free-standing films based on MnO2@multi-walled carbon nanotubes (MWCNTs)@Polypyrrole (PPy) have been fabricated for aqueous zinc-ion batteries. A simple hydrothermal method was adopted to synthesize ß-MnO2 nanowires. PPy coated the ß-MnO2 nanowires@MWCNTs composite by an in-situ polymerization process. Free-standing films of ß-MnO2@MWCNTs@PPy composite were prepared by a convenient vacuum-assisted filtration. A zinc-ion battery is fabricated with a zinc foil anode and a ß-MnO2@MWCNTs@PPy composite cathode. The Zn//ß-MnO2@ MWCNTs@PPy system in ZnSO4@MnSO4 aqueous electrolyte exhibits high electrochemical performances, such as an initial capacity of 258.5 mAh g-1 at 0.2 A g-1, and about 74.6% retention after 100 cycles with near 100% Coulombic efficiency. The strategy of conductive polymer coating makes the technology of rechargeable zinc-ion batteries (ZIBs) very promising and provides opportunities of organic-inorganic composite materials for energy storage applications.

For the purpose of enhancing the solubility and humidity stability of pymetrozine (PMZ), a highly active but nonbiocidal pesticide, new multicomponent crystals were developed based on the connotati...

Two-dimensional (2D) materials have attracted extensive attention for use in fiber lasers for pulse generation due to their unique nonlinear optical properties. While 2D materials with tunable band...

2024-T3 aeronautical aluminum alloy is a high-strength hard aluminum alloy, belonging to the Al-Cu-Mg series. It is mainly used for manufacturing various high-load mechanical parts such as aircraft...

The synthesis of the first cellulose-based vitrimer is described. Dynamic ester bonds were responsible for the dynamic properties of carboxymethyl cellulose (CMC)-based vitrimer. The addition of suitable catalyst and glycerol in the vitrimer formulations was crucial for the reprocessability of these materials. Thermogravimetric and dynamic mechanical analyses tensile strength tests were performed to investigate the effect of the catalyst and glycerol on the thermal stability and mechanical properties of the materials. A minimum amount of 5 mol% of 1,5,7-triazabicyclo[4.4.0]dec-5-ene with respect to the carboxyl group content was required to maintain reprocessability by hot press. The CMC vitrimer exhibited good reprocessability and shape memory ability. Our work demonstrates that cellulose, the most abundant bio-resource on the planet, can be a promising raw material for bio-based vitrimer due to its excellent renewability and low cost.

TRC permanent formwork is made of a new type of cement-based material and has wide application prospects in formwork engineering. To promote the large-scale development of TRC permanent formwork and make it widely used in engineering practice, based on the single-lap shear test, this paper analyses the bonding properties between the TRC permanent formwork and cast-in-place concrete at different lengths in terms of the failure mode, load-slip curve, etc., and further elaborates on the fracture mechanics theory. The research shows that when the length of the formwork small, the failure mode of the specimen measured by the single-lap shear test mainly occurs at the textile-matrix interface in the TRC permanent formwork; when the length of the TRC formwork large, the failure mode begins to change to textile fracture. The effective bonding length of the TRC permanent formwork and the cast-in-place concrete is approximately 150 mm. When the TRC formwork length is less than 150 mm, the interface bonding force increases continuously with increasing TRC formwork length. The load-slip is mainly divided into two curves with typical characteristics. The first type of curve has a clear load softening stage, and the whole curve of the second type has a stage where the slip increment is small and the load drops sharply. Finally, the interface fracture energy can better characterize the interfacial bonding properties between TRC permanent formwork and cast-in-place concrete.

This paper presents a technique for suppressing specific resonance modes of micromechanical resonators by mechanical means. In particular, attaching multiple miniaturized beam structures with properly designed dimensions acting as anti-resonating tuned mass dampers (TMD’s) to a micromechanical clamped-clamped beam (CC-beam) resonator based on a CMOS-MEMS process platform successfully attenuate the dynamic frequency response of the fundamental mode while retaining the $2^{\mathrm {nd}}$ harmonic mode of the CC-beam. The measured results show that the frequency transmission response of the TMD-embedded CC beam drops as much as $\sim 12$ dB compared to that of a reference resonator. An analytical model is used to study the effects of the parameter variations of the TMD structures. This technique provides an alternative approach to mechanically suppressing vibration modes for the micromechanical resonators that cannot employ the conventional quarter-wavelength support technique. [2020-0289]

HVOF coatings generally have a high bonding strength and good compactness, which improve the wear, corrosion, high-temperature oxidation, and fatigue properties of the substrate. They are widely used in automobile, home appliance, petrochemical, aerospace, and other fields. The flame flow characteristics and particle in-flight behaviors during the spray process have an essential influence on the coating microstructure and, thus, properties. This paper deals with a flow field model of a HVOF process that uses kerosene as fuel. A one-step chemical reaction model and the eddy dissipation model were used to numerically calculate the flame dynamics. The numerical simulations predicted the variation laws of flame pressure, temperature, velocity, Mach number, and combustion components. On this basis, the temperature, velocity, and trajectory of WC-12Co particles were calculated using a Lagrangian approach. The effect of the oxygen/fuel ratio on the flame flow and particles characteristics was analyzed, as well as the effect of particle diameter, shape, injection angle, and nitrogen flow rate on particle in-flight processing.

Bimetallic oxide NiCo2O4 and its composites hold promising applications for supercapacitors owing to their theoretical capacity, inexpensiveness, and ease of synthesis. In this work, novel CuO/Cu2O/NiCo2O4 (CCNC) open-structured three-dimensional (3D) composites were synthesized. The multiple components and open structure of the composite provide many open channels for ion diffusion, thus, promoting good rate performance during the electrochemical reaction. The optimized sample (CCNC3–6) shows good electrochemical performance, with a high specific capacitance of 1614 F g−1 at a current density of 1 A g−1, and good rate performance by maintaining a capacitance of 1383 F g−1 for increasing current density to 20 A g−1 (with a merely 14% capacitance loss, as compared with that at 1 A g−1). The composite also shows enhanced cycle stability than pure NiCo2O4, with 81% remaining capacitance after 3000 cycles. The CCNC 3D nanocomposites are demonstrated to be promising for high-performance supercapacitor applications.

The “Hot exciton” channel material can take into account both maximizing exciton utilization efficiency (EUE) and maximizing photoluminescent quantum yield (PLQY). It is a new material with broad application prospects. In this article, starting from the classical D–A molecular model system, the long-range correction functional ωb97x, which can accurately describe the CT state, was selected for the excited state calculation. We extended the D–A system to the X-B-D system. In order to preserve the large ΔET1–T2, we selected the NZ group as the central core B; we chose a donor group 10H-phenoxazine (X1) and an acceptor group 1,3,4,6,7,9,9b-heptaazap-henalene (X2) as part X, and 10 donors with different HOMO as part D. By simulating the ground state and excited state properties of these 20 molecules, we found that compared with the traditional D–A molecule, the excited state of the X-B-D molecules underwent more CT or HLCT transition; the number of channels for the reverse intersystem crossing increased from one to multiple, which may provide a new idea for the design of new multi-channel “Hot exciton” materials.

Aqueous full K-ion batteries (AFKIBs) featuring high safety, low cost, and environmental friendliness represent the future of advanced energy storage technologies. However, current AFKIB systems are still in need of suitable electrolytes and electrode materials, not to mention durability. Here, we report a “rocking-chair” type aqueous full K-ion system with KTi2(PO4)3/C crystalline nanoparticles as the anode material with near zero-strain, iron hexacyanoferrate as the cathode, and 21 m KCF3SO3 as a water-in-salt electrolyte. Benefitting from the fast reaction kinetics and high structural stability of KTi2(PO4)3/C, the full battery achieves a high capacity retention of 96.7% over 30 000 cycles, excellent rate performance with full charge and discharge in 1 minute, and a high energy density of 47.3 W h kg−1. Demonstration of the performance of this AFKIB system expands the avenues of exploration for large-scale energy storage.

In order to improve the aqueous solubility of clotrimazole (CLT), an effective antifungal agent, its new multicomponent crystals were developed according to crystal engineering. To efficiently synthesize the multicomponent solids, a protocol which combined a virtual cocrystal screening tool based on the conductor-like screening model for realistic solvents (COSMO-RS) and the experimental liquid-assisted grinding (LAG) method was applied. As a result, fourteen multicomponent crystals were obtained from 21 potential coformers, including 5 previously reported ones. Nine novel multicomponent crystals were identified and characterized by single crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and Fourier-transform infrared spectroscopy. Intermolecular interactions were elucidated by Hirshfeld surface analysis, and the origin of the cocrystals/salts was explained using molecular electrostatic potential surfaces. Finally, powder dissolution experiments were carried out. Compared with CLT, some multicomponent crystals showed an improvement in solubility (3.13–1.53 times) and dissolution rate.

Polymer–nanoparticle (NP) hybrid nanocomposites act as essential elements for ultraflexible memory devices due to their processability, flexibility, and chemical resistance. However, a key limitati...

UV light driven photoelectric properties of ZnO film to humidity were researched. ZnO film was prepared through the method of screen printing sustained on Al2O3 substrate. ZnO was characterized by XRD, FE-SEM and EDX. The time-dependent UV light driven photoelectric properties of ZnO were investigated by exposing it to different bias voltages and different relative humidity (20% RH, 40% RH, 60% RH and 80% RH). On one hand, the photoelectric properties of ZnO increased with the augmenting of bias voltage, which shows that a higher bias causes more separation of carriers. On the other hand, the photocurrent decreased with the increase in relative humidity, which shows that bigger humidity results in smaller photoelectric property. To discuss these results, corresponding possible illustrations for the photoelectric properties under different conditions were proposed.

In this study, the switching characteristics of the GaIn/ZnO–TiO2/AgNWs devices under mechanical stretching conditions are investigated. It is shown that the maximum ON/OFF ratio of the unstretched...

Hetero-structure of AlxGa1-xN/GaN exhibits important applications in high frequency and large power devices. In this paper, AlN/GaN is adopted to optimal design the large power impact avalanche transit time (IMPATT) and mixed tunneling avalanche transit time (MITATT) diodes operating at the atmospheric low loss window frequency of 0.85 THz. The static state and large signal characteristics of the devices are numerically simulated. The values of peak electric field strength, break-down voltage, avalanche voltage, the maximum generation rates of avalanche and tunneling, admittance-frequency relation, output power, conversion efficiency, quality factor of the proposed hetero-structural IMPATT and MITATT diodes are calculated, respectively. Via comparing the obtained results of (n)AlN/(p)GaN and (n)GaN/(p)AlN IMPATT diodes to those of the MITATT counterparts, there exists little performance difference between IMPATT and MITATT devices while implies significant difference between the (n)AlN/(p)GaN and (n)GaN/(p)AlN diodes.

An Al−3.6Cu−1Li alloy was subjected to room temperature rolling and cryorolling to investigate their effects on microstructure evolution and mechanical properties. The microstructure and aging characteristics of the room temperature-rolled and the cryorolled alloys with 70% and 90% of thickness reductions were studied by microstructure analysis and mechanical tests. The samples subjected to cryorolling with 90% of thickness reduction have high strength and good toughness. This is mainly due to the inhibition of dynamic recovery and the accumulation of high-density dislocations in cryorolled samples. In addition, the artificial aging reveals that the temperature at which peak hardness is attained is inversely proportional to the deformation amount and directly proportional to the rolling temperature. Moreover, bright field images of cryorolled samples after aging indicate the existence of T1 (Al2CuLi) precipitates. This suggests that the high stored strain energy enhances the aging kinetics of the alloy, which further promotes the nucleation of T1 phases.

Successes of GaN and SiC electronics in high frequency, large power realm indicate that, the GaN/SiC hetero-structures can be used to design the impact avalanche transit time (IMPATT) diodes operating at Terahertz range, of which holds advantages over homo-structural counterparts in lower noise and reduced tunnel current. Here, the (n)GaN/(p)SiC and (p)GaN/(n)SiC double drift region (DDR) IMPATT diodes operating at 0.85 THz are proposed based on the quantum corrected drift-diffusion (QCDD) model, the performance parameters of static state, large signal and noise properties of the studied devices such as peak electric field intensity, breakdown voltage, optimal negative conductance, output power, conversion efficiency, admittance-frequency relation, quality factor, noise electric field, mean-square noise voltage per band-width and noise measure were numerically calculated and analyzed, which can guide to optimize the GaN/SiC IMPATT diodes.

Hydrogen peroxide (H2O2), as a signaling molecule, plays a vital role in a wide variety of signaling transduction processes, aging, and diseases. However, the excessive production of H2O2 causes various diseases. Herein, we develop a novel method for H2O2 detection in live cells via dark-field scattering spectroscopy with gold triangular nanoprisms (AuTNPs) as probes. The corners of AuTNPs would be gradually oxidatively etched by the strong coordination of Br• which is generated by enzymatic reactions in the presence of horseradish peroxidase (HRP), bromide ion and trace hydrogen peroxide. Benefitting from the morphological change, the single AuTNP based plasmonic nanoprobe shows notable blueshifts and scattering color changes which could be real-time monitored under the dark-field microscopy. The peak position in the scattering spectra of individual AuTNP blueshifts linearly with the increase of H2O2 concentration, and exhibits high sensitivity to H2O2 in a large range from 2.5 to 100 µM with a low detection limit (LOD) of 0.74 µM. Moreover, the experimental results were supported by the simulated results via the finite-difference time-domain (FDTD) method. The nanoprobes have been further used for intracellular H2O2 detection in live cells. Besides, the etching of AuTNP also provides an alternative method to design novel plasmonic logic chips and write-once plasmonic memories.

It is of great significance to analyze the influence mechanism of MIG welding parameters during thermo-mechanical coupling to improve the MIG welding process. In this paper, the Python script and t...

As a significant semiconductor, nickel selenide shows enormous potential and extensive application prospects in the field of sensor, photocatalysis and supercapacitor. In this paper, nickel selenide (Ni3Se2, NiSe) thin films were successfully fabricated on stainless-steel sheet using a facile, effective electrodeposition technique. The morphologies, microstructures and chemical compositions of the thin films are characterized systematically. Electrochemical tests exhibit that the Ni3Se2 and NiSe possess high specific capacitance of 581.1 F/g and 1644.7 F/g, respectively. A flexible, all-solid-state asymmetric supercapacitor is assembled by utilizing NiSe film as positive electrode and activated carbon as negative electrode. The solid device delivers a high areal capacitance of 27.0 mF/cm2 at the current density of 0.7 mA/cm2. The maximum volumetric energy density and power density of the NiSe//AC asymmetric SCs can achieve 0.26 mWh/cm3 and 33.35 mW/cm3, respectively. The device shows robust cycling stability with 84.6% capacitance retention after 10,000 cycles, outstanding flexibility and satisfactory mechanical stability. Moreover, two devices in series can light up a red light-emitting diode, which displayed great potential applications for energy storage.

Dust dispersibility, the tendency of dust to form clouds that remain airborne, can be an important safety parameter in preventing dust explosion. One measure to moderate dust explosion hazards is adding solid inertants to combustible dust. In addition to being a solid inertant, noncombustible silica is sometimes used as an anti-caking agent or fluidization enhancement additive in powder systems, affecting particle interactions in dust clouds. In this study, six types of combustible dust were admixed with micro- and nano-sized silica to study the effect on dispersibility and ignition hazard in a Godbert-Greenwald (G-G) furnace. Both micro- and nano-silica increased dispersion for some dust types, by changing contact geometry between combustible particles, and thereby decreasing inter-particle forces. Only for polyethylene did addition of 1% micro-silica cause increased dispersibility resulting in enhanced ignition hazard, with minimum ignition temperature (MIT) slightly decreasing 10 °C. No reduced MIT values were found with 1% nano-silica.

This paper used the finite element method to analyse surface water distribution characteristics on porous asphalt layer under unsaturated seepage, and further compared the critical rainfall intensi...