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Biomass-derived dynamic covalent thermoset has been considered as a promising solution to the high dependence on fossil resources and the difficulty in recyclability after curing of conventional bisphenol A epoxy resins. However, the design and preparation of a dynamic covalent biobased epoxy thermoset with both comparable thermal and mechanical performances to bisphenol A epoxy resins and reprocessibility remains a significant challenge. Herein, based on imine chemistry, a novel Schiff base-containing dynamic covalent epoxy thermoset was facilely fabricated from biobased protocatechualdehyde and synthetic siloxane diamine. Due to the more reactive epoxides in the epoxy monomer than in bisphenol A epoxy oligomer, the thermoset exhibited a high cross-linking density, resulting in high thermal stability and glass transition temperature. The rigid aromatic Schiff base moieties endowed the thermoset with excellent mechanical properties: thanks to the plasticization of the flexible siloxane, the thermoset displayed high impact strength. Meanwhile, owing to the high segmental mobility, the fast exchange of imine bonds was guaranteed; and the thermoset was able to be recycled through reprocessing. Taking these features, this work provided great potential for designing and preparing sustainable substitutes for bisphenol A epoxy resins in the high-performance applications.

Background The yield rate for the synthesis of large-area and high-quality graphene, based on the chemical vapor deposition (CVD) method, is limited by the reactor size of a tubular furnace. Additionally, the reported methods to achieve a high-throughput process are still challenging. Currently, the rolled-up or vertically stacked configuration setup is applied to increase the loading growth. However, the reported methods limit the kinetic reaction of CVD growth and lead to the degradation of the uniformity and crystallinity of as-grown graphene. Methods Here, we propose a novel method to produce a high-yield and uniform monolayer graphene film by helical stacking of Cu with highly porous carbon cloth as an efficient interdiffusion mediator. Additionally, computational fluid dynamics (CFD) is applied to simulate the dynamic distribution within the mediator. Significant Findings This method allows the rapid synthesis of graphene films of up to 900 cm2 for each batch of growth in a 1-inch furnace. Graphene with optimized conditions exhibits a high crystallinity (ID/IG: 0.16) and electrical conductivity (760 Ω/sq). The comprehensive study on recipe optimization together with the multiphysical simulation suggests that the proposed carbon cloth is an ideal spacing mediator for CVD graphene with a high Cu-loading density. This enhancement is attributed to the homogeneous interdiffusion of reactive gas/species in both the transverse and radial directions, resulting in homogeneous nucleation and equivalent kinetic growth. The capacity could reach 15.56 m2/hour in an 8-inch system. The CFD simulation indicates that the porous mediator can improve gas distribution and balance the pressure between the Cu foils to enhance high-yield graphene synthesis. This method provides an efficient strategy for the synthesis of high-throughput and large-area CVD graphene films, which is beneficial for cost-effective and versatile graphene-based applications.

Under the joint action of electromagnetic swirling flow in the nozzle (EMSFN) and mold electromagnetic stirring, Liquid level fluctuation in the mold is investigated to find the optimal combination parameters for the occurrence time of the minimum macrosegregation degree in continuous casting of round billet. When the current intensity of EMSFN device is 450 A, the optimal carbon range 0.045 pct appears, after the fluctuation reaches the minimum with the current intensity at 400 A.

Er3+–Yb3+–Mo6+ co-doped TiO2/Yb2Ti2O7 up-conversion luminescent nanofibers have been successfully synthesized using the electrospinning technology followed by thermolysis. The effects of the precursor ratio and annealing process on up-conversion luminescent character were investigated. The phase of TiO2 was determined to be either anatase or rutile. And the cubic Yb2Ti2O7 in Er3+–Yb3+–Mo6+ co-doped TiO2 phosphor was confirmed. After annealing at high temperature, the up-conversion luminescent intensity of the studied system increased obviously. The fluorescence intensity ratio (FIR) used to be made on the basis of green up-conversion emissions. It was studied as a function of temperature. The maximum rate of sensitivity was ~0.01 K−1 in the range of 300–600 K. The results indicate that Er3+–Yb3+–Mo6+ co-doped TiO2/Yb2Ti2O7 phosphor is a brand-new material that meets the requirement of the optical temperature sensing.

The process of transient liquid phase bonding to form intermetallic compound solder joints can effectively achieve 3D chip stack interconnection. However, there are a large number of void defects in IMC solder joints due to the rapid reaction between elements, which reduces the reliability of the chip stack interconnection. In this study, the interfacial reaction, shear behavior and microhardness of Cu Sn TLP bonding joints were investigated by adding 0.5 wt% CuZnAl powder into the pure Sn interconnect solder. Adding CuZnAl powder can remarkably retard the growth of intermetallic compound and voids in the bonding joints, which is attributed to the fact that CuZnAl powder can reduce the concentration gradient of Cu in the interface region. Compared with the Cu-Sn-Cu bonding joints, the shear strength of composite bonding joints was increased by 12%–19.7%, and the microhardness of composite bonding joints was also improved.

The hot flow behaviors, microstructure evolution and fractographs were studied to optimize the hot forming process of the TA32 titanium alloy thin-walled part. A set of microstructure-based constitutive equations were developed based on the experimental data, which described the relationships among the hot flow stresses and the evolution of phase volume fraction, dislocation density, grain size and damage. The constitutive model was imported into ABAQUS 6.14 to simulate the hot forming process for a typical thin-walled part. The effective strain, dislocation density and damage distribution as well as forming defects of formed parts under different process parameters were predicted. A qualified part without wrinkling and fracture defects was produced at a loading speed of 5 mm/s at 800 °C by the modified blank shape, where the maximum damage value was only 18.3%. The accuracy of constitutive model and finite element (FE) simulation was verified by the microhardness tests, which indicates that the FE model based on physical internal-state variables can well optimize the hot forming process of TA32 titanium alloy complex parts.

Large bubbles seriously reduce the efficiencies of the interactions between the bubbles and the molten steel, such as energy transfer, momentum transfer, mass transfer and chemical reaction. To reduce the size of the bubbles and increase the gas–liquid interface area, a novel non-intrusive method of bubble refinement was proposed, which only depends on the molten steel flow field controlled by the rotating electromagnetic field. The flow fields of the molten steel for bubble refinement were analyzed, and the corresponding bubble refinement was investigated. It was found that the molten steel formed obvious rotating turbulent flow for bubble refinement under the unidirectional rotating electromagnetic field. However, the large vortex in the center of the molten pool caused by the rotating flow made the bubbles aggregate and coalesce again, resulting in formation of larger bubbles and gas cavity. To suppress the central vortex formation and enhance the bubble refinement, the forward-reverse rotating electromagnetic field for bubble refinement was proposed. The irregular and chaotic flow occurred repeatedly because of alternating forward and reverse rotating in a short period, so that the turbulent kinetic energy and turbulent dissipation of the flow field always remained at a high level which favors bubble refinement. As a result, the bubble diameter can decrease by more than 50% compared to that without electromagnetic field. Furthermore, it is important that this non-intrusive kind of bubble refinement method completely avoids the introduction of non-metallic inclusions caused by intrusive configuration.

The characteristics of structural changes, Fe magnetic moment and electronic structure of TM (TM = Co, Ni, Rh, Pd, Ir and Pt)-doped AFe2As2 (A = Ba, Sr) were studied by first-principles calculations. After the introduction of the dopants, almost all the Fe–Fe distances become longer. The nesting between the electron pockets and the hole pockets is formed. The Fermi level has a tendency to move from the hole band to the electron band. With the decrease in Fe magnetic moment, the width of Fe 3d and As 4p hybridized bands is increased, which is considered to be the decrease in electronic localized character and the increase in itinerary. The observed common features in our calculations provide information on the generation of superconductivity in iron-based superconductors AFe2As2 (A = Ba, Sr).

In this letter, the electronic transport features of layered two-dimensional (2D) Bi2 O2 Se semiconductor nanosheets are characterized along the in-plane and the out-of-plane directions, respectively. The modulation of double gate is manufactured on a 26.4 nm CVD-grown Bi2 O2 Se-nanosheet MOSFET, thus executing the highest in-plane field-effect mobility of ~296 cm2 V−1s−1 at room temperature. Furthermore, the rectification behavior of charge transport across the perpendicular interlayer of Bi2 O2 Se nanosheet is distinctly scrutinized. Correspondingly, the existing of potential barrier between the [Bi2 O2] ${}^{2n+}$ and [Se] ${}^{2n-}$ interlayers of Bi2 O2 Se nanosheets is validated by the temperature-dependent current measurement and the Poole-Frenkel model. This work offers promising routes to implement high-efficient field-effect transports parallel to the in-plane direction, as well as tunable heterojunction transports across the perpendicular interlayer of 2D Bi2 O2 Se nanosheets.

The effect of various aging modes and preliminary tension (3%) on the microstructure and mechanical properties of Al – Li alloy 2A97-T3 (1.31% Li, 3.55% Cu, 0.37% Mg, the remainder aluminum) is studied. Scanning electron microscopy in combination with energy-dispersive spectroscopy and EBSD analysis are applied. The ultimate tensile strength is determined.

An efficient, sustainable and energy conservation system and method for color stripping of reactive dyes on cotton substrate in a dipping manner were constructed for the first time via a UV irradiation of potassium persulfate (K2S2O8) in aqueous system to photocatalytically generate working species at an ambient temperature. The results show that the active species in the developed UV/K2S2O8 system could efficiently attack and decolorize the model dye as well as other applied reactive dyes after being fixed on cotton substrate with high selectivity. An efficient and significant improvement of color stripping was available with a color stripping ratio higher than 90.0% even at a stripping duration of 30.0 min. High efficiencies in color stripping of 14 commercial reactive dyes involving various chromophoric matrixes on cotton substrate were also achieved in the stripping system with a recommended process, accompanied with commercially satisfactory tensile strength retentions of the substrate. The color stripping on the substrate in the UV/K2S2O8 system was further traced and explored successfully by Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy (SEM) analysis. Additionally, a possible working mechanism of the developed system for color stripping on the substrate was also proposed.

Titanium coating was deposited on the diamond surface by the vacuum micro-vapor deposition method to improve the wettability and enhance the interfacial bonding between diamond and copper. The Ti-coated diamonds were used as the reinforcement particles to fabricate Ti-coated diamond/copper composites by the spark plasma sintering, and the effects of process parameters on the microstructure and thermal conductivity of Ti-coated diamond/copper composites were systematically considered. SEM, EDS, and XRD methods were adopted to analyze the microstructure characteristics and interlayer of the composites. It was showed that TiC formed homogenously, continuous and compactly, aside from some tiny porous appearing on the diamond surface and the thickness of Ti coating was about 300 nm. The TiC interlayer strengthened the interfacial bonding, bridged the diamond particles with copper matrix perfectly, and the formation of compacted Ti-coated diamond/copper composites was verified by microscopic analysis. The relative density of Ti-coated diamond/copper composites was 98.72%, but the thermal conductivity of the composites was only 230.82 W/m*K at the optimal process parameters of 900 °C, 80 MPa, and 40 min, mainly due to some cavities existed at the Ti-coated diamond surface which caused phonons to scatter and decreased the TC of the composites.

The deformation mechanism of C5191 phosphor bronze sheet under ultra-high-speed blanking was investigated. By virtue of a DOBBY-OMEGA F1 ultra-high-speed press, the ultra-high-speed blanking test was conducted on C5191 phosphor bronze sheets with a thickness of 0.12 mm at 3000 strokes per minute. The microstructures of the blanked edges were characterized and analyzed separately by electron back-scatter diffraction (EBSD) and transmission electron microscopy (TEM). The results show that grains in the blanked edges are stretched along the blanking direction. Strong {001}〈100〉 cube textures (maximum pole densities of 9 and 12, respectively) and secondarily strong {011}〈011〉 textures (maximum pole densities of 4 and 7, respectively) are formed in local zones. Additionally, deformation twins are found in the shear zone of the blanked edges which are rotated and coarsened due to the blanking-induced extrusion and local thermal effect which can further form into sub-grains with clear and high-angle boundaries. The C5191 phosphor bronze sheet is subjected to adiabatic shear during ultra-high-speed blanking, accompanied with dynamic recrystallization.

This paper conducted an experimental study of droplet behavior characteristics occurring within a burning aviation kerosene droplet and on the droplet interface. The droplet combustion was performed in a quiescent high-temperature environment by means of the droplet suspension technique. The soot particles were used as tracers to visualize the fluid motion in the droplet. The shape variation of droplet, internal flow pattern in the burning droplet, and instabilities at gas-liquid phase interface were recorded by a high speed camera. The internal fluid flow in the droplet was revealed to be caused by the Marangoni effect, which was generated because of the surface tension gradient induced by the temperature gradient on the droplet surface. The studies showed that the Marangoni effect has a significant impact on the internal flow. The amplitude of the capillary waves on the surface of the droplet was non-uniform and presented the amplitude characteristics of large-small-some. The wavelength of the capillary waves for burning aviation kerosene droplet ranged from 110 µm to 120 µm.

Usages of plastic casing have a number of drawbacks like generation of waste associated with the materials used to package foods and the source of natural casings is limited. So, the interest in the development of biodegradable collagen casing is increasing. For this reason, the present study aimed at developing a new type of collagen casing sprayed with Tea Polyphenols (TP), sodium alginate and sodium pyrophosphate. Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was used to optimize concentrations of TP, sodium alginate and sodium pyrophosphate for the development of collagen casing. The optimization was done on the basis of responses viz. tensile force, tensile strength and elongation at break. The results showed that TP has a significant influence on tensile force and longitudinal tensile strength of collagen casing. Moreover, sodium alginate and sodium pyrophosphate had a significant effect on transverse elongation at break of collagen casing. The optimum level of different parameters resulting in collagen casing with maximum mechanical properties were obtained under conditions of 1.99% TP, 2.90% sodium alginate and 2.99% sodium pyrophosphate concentrations. Further verification test of the optimized conditions revealed a sufficient specific accuracy. The new type of collagen casing exhibited good mechanical properties, so these casings can be utilized for packaging in sausage industry.

Various strategies for preparing highly oriented architectures in hydrogels remain challenging as the regulation of macromolecular chains is often restricted by electrostatic, hydrogen bond and other interactions, and a single strategy is not capable of breaking the equilibrium limits. In this study, a highly aligned cellulose hydrogel was fabricated with high birefringence (∼6.4 × 10−3) and high water content (∼72%) by alternately immersing the hydrogel in water and CaCl2 solution. By a H2O/Ca2+ exchange, the dominant interaction of cellulose molecules switched between H-bond and ionic coordination, so as to achieve continuous regulation of orientation. Moreover, using flexibly programmable exchange strategies, bilayer, gradient anisotropic, opposite anisotropic and adjacent anisotropic cellulose hydrogels were fabricated with precise control of local orientation. Diverse self-shaping gels including rings, hollow rectangles, hollow triangles and elastic springs can be prepared on variable surfaces without any inverted molds. This principle may provide new ideas and inspirations for constructing highly oriented structures and develop new avenues to produce versatile stimulus-responsive anisotropic materials.

Cellulose Nanofibrils (CNFs) were exposed to a certain amount of sodium chloride (NaCl) before being subjected to two types of drying methods (freeze drying and vacuum drying). The effect of two drying methods on water redispersibility of CNFs was investigated by characterizing product morphology, particle size distribution, water stability, and surface chemistry. The results showed that vacuum drying was favorable for the redispersion of CNFs with NaCl resulted in more homogenous fibril structure with lower mean particle sizes and higher water stability. Fourier transform-infrared spectroscopy (FT-IR) and Energy-dispersive X-ray Spectroscopy (EDX) experiments indicated that vacuum drying at pH 8 was more conducive to complexation between Na+ and carboxyl, hydroxyl groups favorable for CNF redispersion. Furthermore, NaCl is cheap, and the process is very straightforward which does not require any organic solvents or hazardous chemicals. Therefore, vacuum drying with NaCl may be considered as a green and economically feasible method for preparation of water redispersible dried CNFs.

Even though “metal-free” carbonaceous electrocatalysts like heteroatom(s)-doped graphene exhibit several advantages, such as cost-effectiveness and high stability toward hydrogen evolution reaction...

Although many previous studies have investigated the shear behaviour of single rock joints, few of them have focused on the shear behaviour of multi-joint rock specimens under constant normal stiffness boundary conditions. This study describes the manufacture of a series of rock specimens containing multiple parallel rough joints and estimates the role of surface roughness and spacing of joints during shearing. The results show that the upper joint is crushed while the lower joint is scratched after shearing for a two-joint specimen. The middle joint is more significantly damaged/scratched than the upper and lower joints after shearing for a three-joint specimen. The joint surface roughness plays a clearer role on the variations in shear stress, normal displacement and normal stress for a three-joint specimen than that for a two-joint specimen. With the increment of shear displacement, the surface resistance index (SRI) defined as the ratio of shear stress to normal stress exhibits peak values and residual values. As the spacing of joints increases, the peak SRI generally increases at a rate in the range of 0·15–0·22/cm, except for one specimen containing three joints with a relatively rough surface.

Acetone is a main respiratory marker for diabetic patients. In this paper, P-type NiO nanofibers were prepared by electrospinning and used for the detection of acetone gas. NiO nanofibers were characterized by SEM and XRD. The uniform NiO nanofibers with face-centered cubic structure was obtained. The working temperature of NiO nanofibers was optimized, and the optimal operating temperature is 220°C. The response-recovery curve was tested, and the response and recovery time is 24.6 s and 610 s respectively. The response to different concentrations of acetone was also analyzed, and the detection limit was 100 ppb. These results show that NiO nanofibers based on electrospinning have potential applications in the respiratory testing of diabetes.

The relationship among microstructure, mechanical properties and texture of TA32 titanium alloy sheets during hot tensile deformation at 800 °C was investigated. In the test, the original sheet exhibited relatively low flow stress and sound plasticity, and increasing the heat treatment temperature resulted in an increased ultimate tensile strength (UTS) and a decreased elongation (EL). The deformation mechanism of TA32 alloy was dominated by high angle grain boundaries sliding and coordinated by dislocation motion. The coarsening of grains and the annihilation of dislocations in heat-treated specimens weakened the deformation ability of material, which led to the increase in flow stress. Based on the high-temperature creep equation, the quantitative relationship between microstructure and flow stress was established. The grain size exponent and α phase strength constant of TA32 alloy were calculated to be 1.57 and 549.58 MPa, respectively. The flow stress was accurately predicted by combining with the corresponding phase volume fraction and grain size. Besides, the deformation behavior of TA32 alloy was also dependent on the orientation of predominant α phase, and the main slip mode was the activation of prismatic 〈a〉 slip system. The decrease of near prism-oriented texture in heat-treated specimens resulted in the enhancement of strength of the material.

Helical strakes have been widely applied for suppressing the vibration of flexible cylinders undergoing vortex-shedding in offshore engineering. However, most research works have concerned on the application of helical strakes for the isolated flexible cylinder subjected to vortex-induced vibration (VIV). The effectiveness of helical strakes attached to side-by-side flexible cylinders in vibration reduction is still unclear. In this paper, the response characteristics of two side-by-side flexible cylinders with and without helical strakes were experimentally investigated in a towing tank. The configuration of the helical strakes used in the experiment had a pitch of 17.5D and a height of 0.25D (where D is the cylinder diameter), which is usually considered the most effective for VIV suppression of isolated marine risers and tendons. The center-to-center distance of the two cylinders was 3.0D. The uniform flow with a velocity ranging from 0.05 m/s to 1.0 m/s was generated by towing the cylinder models along the tank. Experimental results, including the displacement amplitude, the dominant frequency, the dominant mode, and the mean drag force coefficient, were summarized and discussed. For the case where only one cylinder in the two-cylinder system had helical strakes, the experimental results indicated that helical strakes can remarkably reduce the flow-induced vibration (FIV) of the staked cylinder. For the case of two straked cylinders in a side-by-side arrangement, it was found that the performance of helical strakes in suppressing the FIV is as good as that for the isolated cylinder.

In this study, reduced graphene oxide (rGO)/boron nitride (BN) anisotropic aerogels (CGAs) used as the heat conduction network were prepared by one-step heat flow method to improve the low thermal conductivity and low heat transfer efficiency of phase change materials. Composite phase change materials (CPCMs) were obtained after vacuum adsorption of paraffin. The structure and thermal properties of the samples were then characterized. The results showed that the anisotropic aerogel was successfully prepared and the corresponding CPCM axial thermal conductivity was 1.68 W/(m K) when the graphene oxide (GO)/BN used to prepare the CGA was 1:20, which was 504% higher than pure paraffin. After 50 cycles, the paraffin leakage rate was 3.1%, and the enthalpy loss rate was 2.7%. When simulating the actual temperature change, the paraffin phase change time could be advanced by approximately 1210 s, and the paraffin phase change efficiency could be improved by approximately 47%. CPCMs have high thermal conductivity, high heat transfer efficiency, and high thermal conduction network stability. They exhibit high heat transfer efficiency and can be used in the fields of thermal energy storage and solar energy conversion and so on.

This study proposes a double-rough-walled fracture model to represent the natural geometries of rough fractures. The rough surface is generated using a modified successive random additions (SRA) algorithm and the aperture distribution during shearing is calculated using a mechanistic model. The shear-flow simulations are performed by directly solving the Navier-Stokes (NS) equations. The results show that the double-rough-walled fracture model can improve the accuracy of fluid flow simulations by approximately 14.99%–19.77%, compared with the commonly used single-rough-walled fracture model. The ratio of flow rate to hydraulic gradient increases by one order of magnitude for fluids in a linear flow regime with increment of shear displacement from 2.2 mm to 2.6 mm. By solving the NS equations, the inertial effect is taken into account and the significant eddies are simulated and numerically visualized, which are not easy to be captured in conventional experiments. The anisotropy of fluid flow in the linear regime during shearing is robustly enhanced as the shearing advances; however, it is either increased or decreased for fluids in the nonlinear flow regime, depending on the geometry of shear-induced void spaces between the two rough walls of the fracture. The present study provides a method to represent the real geometry of fractures during shearing and to simulate fluid flow by directly solving the NS equations, which can be potentially utilized in many applications such as heat and mass transfer, contaminant transport, and coupled hydro-thermo-mechanical processes within rock fractures/fracture networks. Keywords: Double-rough-walled fracture, Navier-Stokes (NS) equations, Anisotropy, Fractal dimension

In this study, a novel type of high-strength regenerated cellulose composite fiber reinforced with cellulose nanofibrils (CNFs) and nanosilica (nano-SiO2) was prepared. Adding 1% CNF and 1% nano-SiO2 to pulp/AMIMCl improved the tensile strength of the composite cellulose by 47.46%. The surface of the regenerated fiber exhibited a scaly structure with pores, which could be reduced by adding CNF and nano-SiO2, resulting in the enhancement of physical strength of regenerated fibers. The cellulose/AMIMCl mixture with or without the addition of nanomaterials performed as shear thinning fluids, also known as “pseudoplastic” fluids. Increasing the temperature lowered the viscosity. The yield stress and viscosity sequences were as follows: RCF-CNF2 &gt, RCF-CNF2-SiO22 &gt, RCF-SiO22 &gt, RCF &gt, RCF-CNF1-SiO21. Under the same oscillation frequency, G’ and G” decreased with the increase of temperature, which indicated a reduction in viscoelasticity. A preferred cellulose/AMIMCl mixture was obtained with the addition of 1% CNF and 1% nano-SiO2, by which the viscosity and shear stress of the adhesive were significantly reduced at 80 °C.

International audience; To improve the problem of narrow bandwidth and large crosstalk in high-frequency PMUT array, a PMUT device with a damping backing structure (B-PMUT) is proposed and realized. The device is a two-dimensional array of 8×16 elements with an element pitch of 75 µm. The results show that the bandwidth of the device with backing is more than doubled (63%) to that of without backing. The crosstalk level between two neighboring elements decreased from −13.4 dB to −17 dB.

CeO2 is an important energy storage material that can be used in solid fuel cells. Adding citric acid can improve the particle distribution of the pyrolytic preparation of CeO2 inside the reactor. Through Fluent, this paper investigated the pyrolysis preparation of CeO2 with the addition of citric acid by adopting the Eulerian multiphase flow model, component transportation model, and standard k-ε turbulence model. The experimental and simulation results suggest that the addition of citric acid can alter the pressure, temperature, and component distributions inside the reactor. When the mass fraction of O2 is 0.3, the concentration distribution effect of the CeO2 component is optimal and its conversation rate is the highest. When the mass fraction of citric acid is 0.04, the concentration distribution effect of the CeO2 component is the best, as witnessed by the high CeO2 concentration at the exit. It was found that an O2 content of 30 wt % and citric acid content of 4 wt % were optimal operating conditions for this technology.

Large amounts of pickling liquor are produced during the pickling of iron and steel. The Venturi reactor is used during the pyrolysis of pickling liquor to prepare high-purity Fe2O3 particles. Changing the pyrolysis conditions will affect the purity and concentration of Fe2O3 particles. In this paper, physical experiments and numerical simulations were carried out to study the effect of pyrolysis conditions on the Fe2O3 particles, including the pyrolysis temperature, the FeCl2/FeCl3 ratio in the pickling liquor, and the citric acid ratio. The results showed that a product with a higher purity, better crystallinity, and greater concentration was obtained at 923 K. Further increasing the temperature did not change the concentration of Fe2O3 particles. When the ratio of FeCl2/FeCl3 in the pickling liquor was 1:1.5, the maximum concentration of Fe2O3 particles at the outlet was obtained. When the added proportion of citric acid was 1:1, the particle size distribution was more uniform, and when the added proportion was 1:2.5, the maximum concentration of Fe2O3 particles at the outlet was achieved.

The second near-infrared (NIR II) response photon up-conversion (UC) materials show great application prospects in the fields of biology and optical communication. However, it is still an enormous challenge to obtain efficient NIR II response materials. Herein, we developed a series of Er3+ doping ternary sulfides phosphors with highly efficient UC emissions under 1532 nm irradiation. Excitingly, β-NaYS2:Er3+ achieves a breakthrough visible UC efficiency as high as 6.13%, along with outstanding brightness, spectral stability of lights illumination and temperature. Such efficient UC dominates by excited state absorption process accompanied by the advantage of super long lifetimes of excited state levels of Er3+, instead of the well-recognized energy transfer UC between sensitizer and activator. NaYS2:Er3+ phosphors are further developed for high-performance underwater communication and a narrowband NIR photodetectors. Our findings breakthrough the traditional thinking of realizing efficient UC, and open up a novel frontier for developing NIR II response UC materials.

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.

The extensive use of large-area high temperature superconducting (HTS) thin films has emerged in superconducting microwave devices. The interest in Tl-based HTS films arises from their high critical temperature (Tc), allowing the microwave device made on Tl films to work above the liquid nitrogen temperature zone. Here, we introduce a simplified two-step method to fabricate high-quality Tl2Ba2CaCu2O8 (Tl-2212) films on 2-inch LaAlO3 substrates. This method enables the preparation of Tl-2212 films to be easy and repeatable, promoting the theoretical research and practical applications of Tl-based films. Based on the high reproducibility of this fabricating process, we studied the superconducting properties of Tc, the critical current density Jc (77 K, zero field) and surface resistance (Rs) of 2-inch Tl-2212 films. Results show that the Tc values of the sample films prepared at different conditions vary from 99 K to 103 K, depending on the oxygen content; the Jc of the films ranges from 0.7 to 1.8 MA/cm2, relying on the surface roughness. On the basis of the two-fluid model, the influence of Jc on Rs of the Tl-2212 films is incorporated to explain the variation of Rs in different samples.

Development of n-/p-type semiconducting graphenes is a critical route to implement in graphene-based nanoelectronics and optronics. Compared to the p-type graphene, the n-type graphene is more difficult to be prepared. Recently, phosphorous doping was reported to achieve air-stable and high mobility of n-typed graphene. The phosphorous-doped graphene (P-Gra) by ion implantation is considered as an ideal method for tailoring graphene due to its IC compatible process; however, for a conventional ion implanter, the acceleration energy is in the order of kiloelectron volts (keV), thus severely destroys the sp2 bonding of graphene owing to its high energy of accelerated ions. The introduced defects, therefore, degrade the electrical performance of graphene. Here, for the first time, we report a low-damage n-typed chemical vapor deposition (CVD) graphene by an industrial-compatible ion implanter with an energy of 20 keV where the designed protection layer (thin Au film) covered on as-grown CVD graphene is employed to efficiently reduce defect formation. The additional post-annealing is found to heal the crystal defects of graphene. Moreover, this method allows transferring ultraclean and residue-free P-Gra onto versatile target substrates directly. The doping configuration, crystallinity, and electrical properties on P-Gra were comprehensively studied. The results indicate that the low-damaged P-Gra with a controllable doping concentration of up to 4.22 at % was achieved, which is the highest concentration ever recorded. The doped graphenes with tunable work functions (4.85-4.15 eV) and stable n-type doping while keeping high-carrier mobility are realized. This work contributes to the proof-of-concept for tailoring graphene or 2D materials through doping with an exceptional low defect density by the low energy ion implantation, suggesting a great potential for unconventional doping technologies for next-generation 2D-based nanoelectronics.

In the electromagnetic induction-controlled automated steel teeming (EICAST) technology of ladle, the height and location of the blocking layer are critical factors to determine the structure size and installation location of induction coil. And, they are also the key parameters affecting the successful implementation of this new technology. In this paper, the influence of the liquid steel temperature, the holding time and the alloy composition on the height and location of the blocking layer were studied by numerical simulation. The simulation results were verified by 40 t ladle industrial experiments. Moreover, the regulation approach of the blocking layer was determined, and the determination process of coil size and its installation location were also analyzed. The results show that the location of the blocking layer moves down with the increase in the liquid steel temperature and the holding time. The height of the blocking layer decreases with the increase in the liquid steel temperature; however, it increases with the increase in the holding time. The height and location of the blocking layer can be largely adjusted by changing the alloy composition of filling particles in the upper nozzle. When the liquid steel temperature is 1550 °C, the holding time is 180 min and the alloy composition is confirmed, the melting layer height is 120 mm, and the blocking layer height is 129 mm, which are beneficial to design and installation of induction coil. These results are very important for the industrial implementation of the EICAST technology.

Harvesting energy from human motions for powering portable or wearable electronic devices is attracting attentions in recent years. In this paper, an inertial energy harvester based on a piezoelect...

In the present study, the effects of CuZnAl particles on the wettability, interfacial reaction and mechanical properties of Sn/Cu solder joints during solid–liquid diffusion were investigated. Results show that adding 0.5 wt% CuZnAl particles significantly improved the wettability of Sn solder joints. Increasing the heating temperature or adding N2 atmosphere can also enhance the wettability of the solder joints. The formation and growth of interfacial intermetallic compounds were inhibited by adding CuZnAl particles. For Sn and Sn–0.5CuZnAl solder joints, the diffusion coefficients of Cu6Sn5 were calculated to be 0.01 μm2 s−1 and 0.007 μm2 s−1, respectively. The diffusion coefficients of Cu3Sn were calculated to be 0.0013 μm2 s−1 and 0.0012 μm2 s−1, respectively. In addition, the mechanical properties of Sn–0.5CuZnAl solder joints were better than that of Sn solder joints.

Nanoporous holey-graphene (HG) shows potential versatility in several technological fields, especially in biomedical, water filtration, and energy storage applications. Particularly, for ultrahigh electrochemical energy storage applications, HG has shown promise in addressing the issue of low gravimetric and volumetric energy densities by boosting of the ion-transport efficiency in a high-mass-loaded graphene electrode. However, there are no studies showing complete control over the entire pore architecture and density of HG and their effect on high-rate energy storage. Here, we report a unique and cost-effective method for obtaining well-controlled HG, where a copper nanocatalyst assists the predefined porosity tailoring of the HG and leads to an extraordinary high pore density that exceeds 1 × 10

Determining solid-phase gastric emptying (GE) in a human being is an important application in clinical practice as it can provide valuable information for the diagnosis of related digestive diseases. Currently, 99mTc gastric scintigraphy is considered as the gold standard for measuring GE. However, this method suffers from clinical drawback, such as radiation exposure. This study focuses on identifying alternative methods for GE measurement. Carbon-14 accelerator mass spectrometry (AMS) is a useful tool for biomedical projects due to its inherently high sensitivity and dynamic range, low dose and sample size requirements, and relatively short measurement time. However, it has not yet been implemented in GE tests. In this work, 14C AMS methodology was developed for breath samples. Measurements were conducted on a compact, single-stage AMS device at China Institute of Atomic Energy (CIAE). To investigate GE, micro-doses of 14C-octanoic acid, 13C-octanoic acid, and 99mTc were marked along with tracers in the same test meal and subsequently ingested by volunteers. The 14C-octanoic acid breath test (14C-OBT) in combination with AMS showed better counting statistics than those obtained for the 13C-OBT measured using infrared spectroscopy. The results also demonstrate a considerably lower radiation dose than that in 99mTc gastric scintigraphy. This work establishes an alternative method of 14C-AMS tracing to determine solid-phase GE in a human being, which could provide clinical technical support for a GE test and further expand the range of 14C-AMS applications in biomedicine.

Localized surface plasmon resonances (LSPR) are widely employed for improving the upconversion luminescence (UCL) and photocatalysis. Here, we prepare a nano-semiconductor heterostructure (NSH) consisting of Er-Yb:TiO2 nanosheets (NTs) integrated with plasmonic MoO3-x NTs in a two-step solvothermal processes. The LSPR of MoO3-x amplifies and transfers the near-infrared (NIR) energy to the neighboring Er-Yb:TiO2 UC system, leading to a 182-fold increase in green emissions. Moreover, the LSPR effect extends the absorption range of the Er-Yb:TiO2/MoO3-x NSH from the visible to the NIR region. The interface of the Er-Yb:TiO2/MoO3-x NSH acts as a charge carrier channel to separate the plasmon-induced electrons and holes effectively. We perform H2 production experiments of Er-Yb:TiO2/MoO3-x NSH from ammonia borane (BH3NH3). Upon the excitation of a 980 nm laser, the H2 production of the Er-Yb:TiO2/MoO3-x NSH is 1.5 times and 61 times higher than that of the MoO3-x NTs and BH3NH3. In addition, the H2 yield is 2.5 times and 52 times higher than that of the MoO3-x NTs and BH3NH3 under the irradiation of simulated sunlight (AM 1.5), demonstrating the superior photocatalytic properties of the Er-Yb:TiO2/MoO3-x NSH.

In this paper, a comparative study is reported on tool wear morphology described by machining Be/Cu alloy at different cutting speed:200 m/min,400 m/min,600 m/min,800 m/min and 1000 m/min. The cemented tungsten carbide tools, both coated with TiAlN, are used to test tool life, and the flank wear extent and standard deviation are adopted to describe surface wear pattern. In order to explain the wear mechanism under different cutting speed, a series of theoretical calculation and experiment results were listed in this paper to explain adhesive effect on tool wear under different surface pressure, and results show that the adhesions and wear patterns would be affected by cutting speed and surface pressure. Comparing the relationship between cutting force, cutting heat, surface elements and tool wear, we can easily find out that the hard particle such as Cu and Be adhered to cutting edge to affect tool geometry and strengthen. Besides, the microstructure and generation probability are analyzed to discuss the crystal surface slipping effect on tool wear.

The non-exchangeable organically bound tritium (NE-OBT) concentration in the cellulose of tree rings can accurately reflects the tritiated water concentration in the local environment and often contains the only historical record of tritium exposure. However, there is few study about NE-OBT measurement using AMS around the world, especially in China. Furthermore, in order to measure tritium in tree rings exactly, it is necessary to solve several key problems during sample preparation. In this study, the optimized sample preparations procedure are investigated. The purity of cellulose extracted by improved sodium hypochlorite pretreatment method is about 83.9%, considerably higher than the 64.8% conventional methods. Pure TiH2 samples reaching requirements of AMS measurement have been made. The isotope fractionation is stabilized during sample preparation. Preliminary results of sample analysis using a compact AMS with 200 kV accelerator are presented. Currently, the minimum T/H ratio that can be accurately measured is only about 10−12, limited by hydrogen contents in samples and instrument conditions. Further works will be done in order to achieve lower detection limits and better accuracy.

N, Fe single doped and co-doped anatase TiO2 nanoparticles were successfully prepared by coprecipitation method using TiCl4, NH4OH, Fe(NO3)3·9H2O as raw materials and polyvinyl alcohol as dispersant. The samples were characterized by TG-DSC, FTIR, XRD, FESEM, EDS, XPS, and UV–Vis to investigate the influence of doping concentration on the thermal effect, crystal structure, morphology, composition, energy band gap and photocatalytic activity of TiO2 nanoparticles. Results indicated that TiO2 nanoparticles doped with 0.15 at.% N and 0.3 at.% Fe showed the best photocatalytic activity. N, Fe co-doping had a synergistic effect: (1) The transformation inhibition of anatase to rutile phase was achieved, leading to formation of high crystallized monophasic anatase TiO2; (2) The bandgap narrowing effect was significant, increasing the light absorption range; (3) The small grain size of ~ 10 nm in diameter was obtained, resulting in effective separation of photo-induced electrons and holes.

Silicon carbide whiskers (SiCws) were modified with silane coupling reagent with the aid of ultrasonic agitation, and SiCw/SEBS (styrene-ethylene-butadiene-styrene) grafted with maleic anhydride(SEBS- g-MAH) composites were prepared by a solution method. The effects of modification on the SiCw and the structure morphology, mechanical property, thermal stability, and hydrophobicity of composites were studied. The results show that the tensile strength of composites increased gradually with increasing filler contents, ranging from 19.05 to 24.91 MPa. The pyrolysis temperature of composites to begin to lose mass increased gradually. Comparing with the pure SEBS- g-MAH film beginning to lose mass at 365°C, the composite with 2.5% modified SiCw lost mass at 402°C, which had improved by 37°C. With increasing content of SiCw, the hydrophobicity of composite was enhanced. Compared with the pure SEBS- g-MAH film, the water contact angle of composite with 2.5% SiCw had been enlarged by 40%, from 65.56° to 91.57°.

In this work, Cu/Sn/Cu solder joints were fabricated by low temperature transient liquid phase (TLP) bonding. The microstructure evolution and grain orientation of intermetallic compounds (IMC) in Cu-Sn solder joints were systematically investigated by using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). With the bonding time increased, a typically scallop-type Cu6Sn5 was formed at the interface between Sn/Cu and then gradually thickened to form a full-IMC solder joints. The higher the temperature, the faster the IMC grew. Besides, the asymmetry growth of IMC at both ends of the solder joints was clearly observed due to the temperature gradients. The corresponding EBSD results indicated that Cu6Sn5 and Cu3Sn grains showed the preferred orientation of (001) and (100), respectively. Measurement of the kinetic exponent of IMC suggested that the growth mechanism of Cu3Sn is controlled by grain boundary diffusion. In addition, the wettability and mechanical property of the solder joints were also studied. It was found that the wettability and shear strength of the solder joints improved as the bonding temperature and bonding time increased. The shear fracture analysis of the solder joints revealed that most fractures of the Cu-Sn solder joints have the characteristics of brittle fracture.