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By polymerization of gadolinium methacrylate (Gd (MAA)3), lead methacrylate (Pb(MAA)2) and methyl methacrylate (MMA), Gd and Pb were chemically bonded into polymers. The X-ray shielding performance was evaluated by Monte Carlo simulation method, and the results showed that the more metal functional organic monomer, the better the shielding performance of terpolymers. When the X-ray energy is 65 keV, Gd (MAA)3-containing polymers have better shielding performance than Pb(MAA)2-containing polymers. Gd could compensate for the weak absorption region of Pb. Therefore, polymers containing both Gd and Pb enhanced shielding efficiency against X-ray in various low-energy ranges. For obtaining terpolymers with uniform monomer compositions, the relationship between the monomer composition of the terpolymers and the conversion level was optimized by calculating the reactivity ratios. The value of reactivity ratios of r (Gd (MAA)3/Pb(MAA)2), r (Pb(MAA)2/Gd (MAA)3), r (Gd (MAA)3/MMA), r (MMA/Gd (MAA)3), r (Pb(MAA)2/MMA) and r (MMA/Pb(MAA)2) was 0.483, 0.004, 0.338, 2.508, 0.255, 0.029. The terpolymers with uniform monomer composition could be obtained by controlling the monomer compositions or conversion levels. The results can provide new radiation protection materials and contribute to the improvement in nuclear safety.

Negative Poisson’s ratio structures have attracted great interest due to its many excellent mechanical properties. In recent years, to improve the specific stiffness of the structure, the negative ...

Multiwalled carbon nanotube (MWCNT) and cationic cellulose nanofibril (CCNF) were used to prepare electrothermal films. The mechanical properties, thermal stability, and electric heating performance were investigated by experimental testing and numerical analysis. The results showed that the MWCNT were well dispersed in CCNF matrix. Thermal stability of film was improved, and the maximum decomposition rate was reached at 318 °C. The electrical conductivity increases rapidly after the MWCNT content exceeds 20 wt%, and the electrical conductivity varied from 5.8 × 10−4 S cm−1 and 13.66 S cm−1 with 10–60 wt% MWCNT, the electrothermal films showed strong nonlinearity between I–V and P–V. For the film with 60 wt% MWCNT, the maximum electric power was 3.57 W. The maximum temperature was 93.4 °C and the temperature increased by 279.7% compared with 20% MWCNT content at an applied voltage of 12 V. The average characteristic growth time constant and heat transferred by radiation and convection were 37.24 s and 35.17 mW °C−1, respectively. Therefore, the electrothermal films have a shorter heating parameter and lower electric power consumption as well as excellent thermal cycling stability.

Ceria supported platinum catalyst has now been widely studied due to its excellent activity for CO oxidation. However, the electron state of active metal center is still an open question. In this work, a ceria nanorod support was prepared and platinum (Pt) with 0.9 at% was deposited using an impregnation method to obtain Pt/CeO2 catalyst. With the help of “light-off” experiment and temperature-programmed reduction under CO (CO-TPR) test, the conclusion is proposed that the process of hydrogen reduction can enhance the activity of CO oxidation reaction for the generation of optimal active Pt site. An innovative near-situ X-ray absorption fine structure (XAFS) technique was used to investigate the chemical state of central Pt atom during the reaction process, clearly demonstrating that the high oxidized state of Pt does harm to the activity for CO oxidation while the relatively reductive Pt exhibits high activity, and the different oxidized state and chemical environment of Pt during every process has been identified. Furthermore, the activity of our Pt/CeO2 catalyst is superior to that of most of the previous reports about CO catalytic oxidation by Pt based catalyst. Moreover, the optimal active species (Pt–O4) have been identified after hydrogen reduction, which could be a possible key strategy to control the oxidation of Pt.

The accuracy of the rubber constitutive model characterizing experiment data has a crucial influence on the mechanical analysis of rubber structures. In this paper, a new improved hyperelastic constitutive model is proposed, and the model is derived into the stress-strain forms of uniaxial tension, equibiaxial tension and pure shear. Based on the experimental data of filled rubber, the material parameters of each deformation state are obtained by using the newly proposed rubber hyperelastic constitutive model, and the uniaxial tensile (UT), Equibiaxial tension (ET) and Pure shear (PS) specimens are simulated and calculated in the finite element software. the stress state of each finite element specimen is analyzed and the obtained simulation data are compared with the experimental data. It is found that the new model can accurately characterize the hyperelastic mechanical properties of the experimental specimens in different deformation states. At the same time, the reasons for the deviation from the experimental data in the process of plane tensile simulation are analyzed and explained comprehensively. The reliability and accuracy of the classical rubber constitutive relations of polynomial models and eight-chain model are studied. the results show that different hyperelastic models have different ability to describe the hyperelastic behavior in different deformation states. the hyperelastic constitutive model proposed in this paper can be easily embedded into finite element software and has the advantages of accurate results, few material parameters and simple testing.

An electrocatalytic carbon dioxide reduction reaction (CO2RR) is an appealing route to obtain the value-added feedstocks and alleviate the energy crisis. However, how to achieve high-performance electrocatalysts for CO2 reduction to formate is challenging owing to the poor intrinsic activity, insufficient conductivity, and low surface density of active sites. Herein, we fabricated an extremely active and selective hydrangea-like superstructured micro/nanoreactor of ultrathin bismuth nanosheets through an in situ electrochemical topotactic transformation of hierarchical bismuth oxide formate (BiOCOOH). The resulted bismuth nanosheet superstructure is in the form of three-dimensional intercrossed networks of ultrathin nanosheets, forming an ordered open porous structure through self-assembly, which can be used as a micro/nanoreactor to enable a large electrochemically active surface area as well as high atomic utilization. Such a distinctive nanostructure endows the material with high electrocatalytic performances for CO2 reduction to formate with near-unity Faradaic selectivity (>95%) in a wide potential window from -0.78 to -1.18 V. Furthermore, this micro/nanoreactor can give the high current densities over 300 mA cm-2 at low applied potentials without compromising selectivity in a flow cell reactor. Density functional theory (DFT) and in situ attenuated total reflection-infrared spectroscopy (in situ ATR-IR) were further conducted to interpret the CO2RR mechanisms.

Non-centrosymmetric (NCS) metal chalcogenides are candidates for promising nonlinear optical (NLO) crystals in infrared (IR) bands. However, most research has been focused on sulfides and selenides, with few studies focused on tellurides. For the first time, we systematically investigated the linear-optical and NLO properties of a ternary NLO-active telluride, Ba2Ge2Te5, at the experimental and theoretical levels. It adopts the NCS space group of Pna21 (no. 33) and features an unusual one-dimensional helical chain of [Ge2Te5]4− separated by Ba2+. Ba2Ge2Te5 exhibits a suitable birefringence (Δn) of 0.07, and a giant NLO coefficient d33 of 286.8 pm V−1 at a wavelength of 2050 nm (∼0.61 eV), much larger than that of the reference AgGaS2 (18.2 pm V−1). This work indicates that ethane-like [Ge2Te6] is an instructive NLO-active functional group that can be used to design novel and promising IR-NLO materials.

The electrochemical CO2 reduction reaction (CO2RR) to value-added and readily collectable liquid products is promising but remains a great challenge due to the lack of efficient and robust electrocatalysts. Herein, a self-supported large-size three-dimensional porous conductive network of bismuthene (Bi-ene-NW) as an efficient superstructured electrocatalytic membrane (ECM) has been pioneeringly assembled, in which the atomically thin Bi-ene with rich edge-site-involved defects is interconnected, highly exposing the active sites. Such ECM can be utilized as an ascendant catalytic cathode, displaying an unprecedented CO2RR performance with near-unity selectivity in a wide potential window and large current density for formate production. Remarkably, when integrated into a gas diffusion electrode (GDE) in a flow cell, Bi-ene-NW was capable of delivering industry-compatible current densities up to 560 mA cm−2 for formate production. Moreover, it was ultrastable to continuously operate for over 500 h at a high current density without significant activity decay. Such outstanding performance should be inseparable from its abundant accessible sites with high intrinsic activity, multiple interconnected channels and superior conductivity for mass/charge transport. The operando ATR-IR and theoretical calculations further deciphered that the rich defects in the roughened plane edges and in-plane pore edges of Bi-ene are conducive to the *OCHO intermediate stabilization.

The introduction of coordination polyhedra containing stereo-chemically active lone pairs into the chalcogenide structures is beneficial for realizing centric-to-acentric structural transformation and further enhancing the second-harmonic generation (SHG) efficiency (dij) and the birefringence (Δn) for IR nonlinear optical (NLO) applications; however, this has been rarely reported. Herein, non-centrosymmetric (NCS) arsenates M2As2Q5 (M = Ba, Pb; Q = S, Se) have been screened out by combined experiments and theoretical calculations as a new source of IR NLO materials. Interestingly, they feature unique zero-dimensional structures containing diverse types of discrete As-based coordination polyhedra with M2+ cations located among them, which is discovered for the first time in the IR-NLO chalcogenides. More significantly, they all exhibit multiple key NLO parameters for practical applications in the IR region, including wide phase-matching ranges (>950–1370 nm), remarkable dij (1.0–2.7 × AgGaS2) and large laser-induced damage thresholds (LIDTs = 6.8–12.4 × AgGaS2). Theoretical studies demonstrate that the discrete As-based coordination polyhedra play a critical role in the linear optical and NLO responses of the title compounds. We believe that this work can not only enrich the diversity of NLO-active groups, but also provide a new choice for material design in NCS chalcogenides.

Herein, for the first time, an active and stable bifunctional electrocatalyst has been elaborately designed to achieve the integration of CO2 reduction and anodic non-classical reaction to efficiently yield products of high value at both electrodes, which was constructed by surface anchoring of a novel multi-azido-group-bearing nickel phthalocyanine onto carbon nanotubes at the single-molecule level via strong interactions. Concretely, the obtained heterojunction-type electrocatalyst exhibits ultrahigh activity for completely selective CO2-to-CO conversion with a 100% faradaic efficiency in a wide potential window, large partial current density (>200 mA cm−2) and turnover frequency, and remarkable stability. Particularly, a mass of azido-derived amine groups around the nickel phthalocyanine centers increase the local concentration of CO2via chemisorption, thus boosting the formation of the key intermediate. Unprecedentedly, an exotic electrolytic system integrating CO2 reduction with oxidative nano-polymerization was further conceptually developed using this individual bifunctional electrocatalyst for both the cathode and anode. Besides the high-performance CO2 reduction at the cathode, a unique porous 3D polymer nano-framework was obtained in the anode chamber instead of low-value O2, while the cell voltage was significantly reduced by 1.05 V to achieve 10 mA cm−2.

Constructing high-performance and cost-effective electrocatalysts for water oxidation, particularly for overall water splitting, is extremely needed, whereas still challenging. Herein, based on an economical and facile one-step surface sulfurization strategy, a three-dimensional nanostructure with uniform Fe-doped Ni3S2 nanoparticle arrays tightly implanted on nickel foam (Fe-doped Ni3S2-NF) has been fabricated for the extremely efficient electrochemical oxygen evolution reaction (OER). Owing to the unique electronic structure modulation between Ni and Fe sites, and high interfacial charge communication during the electrocatalytic process, the optimal Fe-doped Ni3S2-NF electrode shows an excellent OER activity with ultralow overpotentials of 166 and 235 mV at 10 and 100 mA cm-2 in alkaline solution, respectively, remarkably outcompeting the benchmark RuO2/NF and the overwhelming majority of the reported electrocatalysts. Furthermore, for overall water splitting, the Fe-doped Ni3S2-NF electrode as a bifunctional electrocatalyst assembled in a two-electrode device requires merely 1.56 V to gain a current density of 10 mA cm-2. This study presents a universal surface engineering strategy to conveniently and economically remould commercial metal materials into efficient electrocatalysts for various electrochemical reactions.

Bismuth (Bi)-based nanomaterials are considered as promising electrocatalysts for the electrocatalytic CO2 reduction reaction (CO2RR), but it is still challenging to achieve high current density and selectivity in a wide potential window. Herein, Cu-decorated Bi/Bi2O3 nanofoam (P–Cu–BiNF) with a 3D porous network structure was prepared for the first time via a simple fast-reduction method. Characterizations indicate that the introduction of Cu can significantly regulate the microstructure and electronic states of Bi/Bi2O3. Consequently, the as-prepared P–Cu–BiNF exhibits excellent electrocatalytic performance toward the CO2RR. Remarkably, the faradaic efficiency of formate production can exceed 90% in a wide potential range from −0.78 to −1.08 V. Meanwhile, it can also deliver a high formate partial current density of up to 62.7 mA cm−2 at −1.18 V and long-term stability. This work provides a simple but effective way to synthesize advanced Bi-based materials with significantly improved electrocatalytic CO2RR performance.

It was found that, just by adding easily accessible and low-cost straight chain fatty acid additives into the co-polymerization reaction system of lead methacrylate with methyl methacrylate, the optical properties of the produced lead-containing plexiglass could be significantly improved. In comparison with the material free of straight chain fatty acid, the light transmittance could be enhanced obviously from 42.97% to 91.84% at the highest, while the haze value was reduced from 94.83% to only 0.39%. Besides, the as-prepared lead-containing plexiglass was of good toughness and mechanical strength. This work may provide key techniques for the fabrication of γ-ray shielding plexiglasses with good optical properties and comprehensive mechanical properties to meet the requirements for atomic energy facilities. This is a significant progress in the atomic energy industry. The technique has been successfully applied in the large-scale production of 1 m × 1 m × 8.0 mm size plexiglass.

High emissivity coating plays a critical role in thermal protective system, which can radiate a large amount of aero-convective heat. Silica sol bonded MoSi2-SiC-Al2O3 (S-MSA) coating was proved to be promising for mullite fibrous insulation. However, the bonding mechanisms of the coating at elevated temperatures are not clear. In this work, the S-MSA coatings were heat-treated at temperatures from 600 °C to 1500 °C to reveal the bonding mechanisms at elevated temperatures. The S-MSA coatings go through a relatively stable stage (600 °C–1000 °C), a crystallization stage (1100 °C–1200 °C), and a densification stage (1300 °C–1500 °C) at ever increasing temperatures. Results show that both the contact damage resistance and the bonding strength of the calcined coatings exhibit a decrease followed by an increase at elevated calcination temperatures, with the inflection point at 1200 °C, corresponding to the transition temperature of the bonding mechanisms from 600 °C to 1500 °C.

In this study, the instability behavior of a confined non-Newtonian liquid jet in an annular gas layer is investigated theoretically. The viscosity of the non-Newtonian liquid is described using the power law model, and the corresponding dispersion relation is obtained by conducting a linear stability analysis. Additionally, the effects of heat and mass transfer, gas-to-liquid axial velocity ratio, power law index, and gas layer thickness on the instability of the power law liquid jet are investigated. The results demonstrate that the heat and mass transfer at the liquid–gas interface destabilizes the power law liquid jet flow. The results also indicate that an increase in the thickness of the gas layer makes the confined power law liquid jet unstable. Furthermore, the confined shear-thickening liquid jet is the most difficult to breakup in comparison with the shear-thinning and Newtonian liquid jets.

MoSi2 has been regarded as one of the most promising structural materials, due to its excellent high-temperature oxidation resistance and high emissivity. However, as the most commonly used emittance agent in high emissivity coatings, it can be easily oxidized when the operating temperature is below 600 °C. To address this issue, the silica-coated MoSi2 powders with good low-temperature (400–600 °C) oxidation resistance were fabricated by a sol-gel method followed by a preoxidation process. Here in, by the combination of the non-isothermal and cyclic-isothermal oxidation analysis, we demonstrate that the silica gel film coated on MoSi2 can prevent oxidation to some extent, but the preoxidation treatment plays a more critical role in improving its oxidation resistance at low temperature. Both the sol-gel and preoxidation processes enable the integrated and compact encapsulation of the silica coating. The synthesized silica-coated MoSi2 exhibits excellent oxidation resistance with slightly weight gains (

The manipulation of luminescence properties of upconversion (UC) materials from micro to macro aspects is of vital importance for disclosing new physical phenomena and expanding the range of applications. In this work, a novel class of SrBi2Nb2O9 (SBN)-based inorganic photochromic (PC) phosphors was synthesized, which exhibited intense susceptibility to visible light irradiation. Large reversible UC modulation ability upon PC effect was realized. Besides, the regulation of UC luminescence was discovered to strongly rely on the irradiation time and heating processes. The mechanisms connected to the UC luminescence, PC effect, and UC manipulation were illustrated. These results demonstrated that SBN-based samples owing high reversible manipulation ratio, fast response, low heating temperature, and excellent reproducibility can be employed as a type of ideal optical medium for future information storage device. In addition, based on the reversible behavior of photochromism, the application of the SBN-based ceramic as an anti-counterfeiting agent was also depicted.

Searching for coexistence of wide energy gap (Eg > 3.5 eV) and large second-harmonic generation efficiency (dij > 0.6  AgGaS2) for the non-centrosymmetric (NCS) materials in the IR nonlinear optic...

The instability of a non-Newtonian liquid sheet in the presence of acoustic oscillations is investigated theoretically. The power-law model is used to describe the viscosity of the non-Newtonian liquid. The corresponding dispersion relation is obtained by linear analysis. The effects of the mean velocity of the gas, the oscillation amplitude, the oscillation frequency, and the gas density on the instability of the power-law liquid sheet are studied. The results show that the shear-thickening liquid sheet is more unstable than Newtonian and shear-thinning liquid sheets when the effects of acoustic oscillations are considered. In particular, a second unstable region appears on the shear-thickening liquid sheet at a low oscillation frequency. Especially, for the shear-thinning liquid sheet, there is a second unstable region in the dispersion curve at a high mean gas velocity. A third unstable region appears on the shear-thinning liquid sheet at a high gas density in the presence of acoustic oscillations. The unstable range of the Newtonian liquid is always the widest among these liquids.

The scalelike coatings with MoSi2 as emittance agent, flake fused quartz as coarse fillers, silica sol as dispersive medium of coating slurry, were prepared on rigid mullite fibrous ceramics to avoid fatal radial cracks and improve thermal shock resistance via combining slurry method with sol-gel method. And the particle size distribution of fused silica was changed to get different crack structure in scalelike coatings. Microstructure and phase composition of the coatings with different crack structure were investigated comprehensively. Contact damage resistance, thermal shock resistance and infrared radiating property were also studied. The results showed that only the coatings with mixing large and small particles of fused silica as coarse fillers could form crack network. The scalelike coatings with crack network went through 25 thermal cycles between 1500 °C and room temperature without peeling and spalling, and the bonding strength did not decrease after test. The scalelike structure with crack network also avoided radial cracks and exhibited some softness and less stiffness in Hertzian indentation test. The emissivity of coatings with different crack structure were all higher than 0.85; and the coatings with lower proportion of crack areas had higher emissivity.

Hydrogen nuclear magnetic resonance (H1-NMR) and X-ray diffractometer (XRD) were used to characterize the molecular and crystal structure of lead methacrylate [Pb(MAA)2] which was produced by the double decomposition reaction of lead oxide and methacrylic acid. Isothermal analysis and Kelen–Tudos (K–T) method were used to study the self-polymerization kinetic and the monomer reactivity ratios of Pb(MAA)2 and methyl methacrylate (MMA), respectively. By the ternary polymerization method of bulk casting using MMA, Pb(MAA)2 and gadolinium methacrylate (Gd(MAA)3) as monomers, we prepared the plexiglass which have neutron and X-ray protection property. The results show that the polymerization rate (Rp) is expressed as Rp = K[M]1.02[I]0.37 below the 10% conversion rate at 70 °C, where K is the polymerization rate constant. And in the N,N-dimethylformamide (DMF) solution, the activation energy required for Pb(MAA)2 to initiate self-polymerization by the free radicals is 74.99 kJ·mol−1. The reactivity ratios of r1 [Pb(MAA)2] and r2 (MMA) are 3.767 and 0.166. As the thickness of the material increases, the X-ray and thermal neutron shielding ability of the plexiglass containing gadolinium and lead is getting better and better.

The heat resistant buoyancy materials were fabricated by the molding method using the aluminum dihydric phosphate as the matrix and hollow glass microspheres as the filler, respectively. In order to improve the waterproof performance of the buoyancy, two strategies, adding the B4C additives and introducing the silica-based coatings, were adopted. The study showed that the samples with the B4C content of 10 wt% possessed the optimal comprehensive performance, such as low density (0.540 g/cm3) and low water absorption (29.6%). The effect of the coating types and coating times on the density, water absorption, compressive strength and specific strength of the buoyancy materials were also studied. After 4 times of coating, the density and the compressive strength of the sample increased to 0.62 g/cm3 and 6.0 MPa, respectively; the water absorption of the samples greatly decreased to 10%. Besides, all samples exhibited significant pseudoductility. The buoyancy materials with the above superior properties can be potentially used in the deep see fields.

Non-centrosymmetric metal chalcogenides such as AgGaS2 and AgGaSe2 are two of the commercial nonlinear optical (NLO) crystals widely used in the infrared (IR) region. Nevertheless, the inherent incompatibility between the wide energy gap (Eg) and large second-harmonic generation (SHG) efficiency (dij) hinders their high-power laser applications. Recently, the development of salt-inclusion chalcogenides with non-centrosymmetric structures has attracted more and more attention and interest owing to their intensive potential applications originating from their wide Eg, strong dij, ultrahigh laser-induced damage thresholds (LIDTs) and large IR transmission range. In this frontier paper, we review the recent progress of salt-inclusion chalcogenides (including 28 related compounds) as favourable candidates for IR-NLO materials, which can be divided into 3 types according to their chemical compositions and structural characteristics: (i) the [RaXb][GanQ2n] type and its derivatives, (ii) [NaBa4Cl][Ge3S10] and its derivatives, and (iii) the [A3X][MB12(MQ4)3] type. The relationships between the non-centrosymmetric structures and NLO properties of these 3 types of compounds are summarized and briefly remarked. In addition, the present challenges of creating new IR-NLO salt-inclusion chalcogenides and future perspectives in this field are discussed.

The microstructural variation and high-temperature flow features of a Ti-55511 alloy in the β region are studied by utilizing double-stage compression with a stepped strain rate. The results demonstrate that the stresses in the latter stage of hot compression markedly reduce as the strain at the previous stage or the strain rate at the previous/latter stage drops. Moreover, the annihilation/interaction of substructures is promoted, and the distinct refinement of the dynamic recrystallization (DRX) in the β grain can be found. However, the coarsening of the β grain and the consumption of dislocation substructures are accelerated at high temperatures. Furthermore, the principal DRX nucleation mechanism of the Ti-55511 alloy during double-stage compression with a stepped strain rate in the β region is discontinuous DRX. Additionally, by using the microstructural variation characteristics related to the forming parameters, a physical mechanism equation is modeled to forecast the forming features, the DRX fraction, and the size of the β grain in the investigated alloy. The forecasted results are in accordance with the tested results, indicating that the established model can accurately forecast the microstructure variation and flow features of the studied alloy.

Intending to achieve more green and economical graphene impregnated modified fast-growing poplar wood veneer for heat conduction, this study proposes and investigates the feasibility of modified veneer with graphene/Polyvinyl alcohol (Gr/PVA) impregnation mixture to improve its thermal conductivity. The absorbance and viscosity of the Gr/PVA impregnation mixtures are observed to expound the Gr/PVA ratio effects on the mixtures. Simultaneously, the weight percent gain, chromatic aberration, and thermal conductivity of the modified veneers are measured to determine the impregnation effect and the optimal impregnation formula. Further, the chemical structure, crystallinity, and thermal stability of the optimal sample impregnated with Gr/PVA are tested. The results show that the thermal properties of the Gr/PVA impregnated modified veneer have not all been improved. Still, both the dispersibility of the impregnation mixtures and the impregnation effect is affected by the Gr/PVA ratio. The data shows that the optimal thermal conductivity of modified veneer, which is up to 0.22 W·m−1·K−1 and 2.4 times the untreated one, is dipped by the mixture of 10 wt.% PVA concentration and 2 wt.% MGEIN addition. According to the characterization tests, the crystallinity of the modified veneer reduces, but the thermal stability improves.

The temporal instability behavior of a non-Newtonian liquid jet in the presence of cavitation bubbles is investigated theoretically. The power law model is selected to describe the viscosity of the non-Newtonian jet. The unstable growth rate is obtained by Chebyshev collocation method. Besides, the effects of the compressibility of liquid, the compressibility of gas, the incorporating compressibility of both liquid and gas on the instability of the power law liquid jet are studied in this case. Especially, energy analysis is performed to study the breakup mechanism of the jet. The results show that the liquid compressibility is a unstable factor on the jet instability. However, the gas compressibility is the factor to prevent the jet from breaking. For the axisymmetric disturbance, it is noted that the viscous force always makes the jet being stable by energy analysis. But for the first asymmetric disturbance, there exists a turning point for the effect of viscosity of the liquid on the jet instability at a large wave number.

High-current superconducting conductors are widely used in fusion magnets, high-energy accelerators, and superconducting power transmission. In order to carry out experimental research on new high-current conductors such as Bi 2 Sr 2 CaCu 2 O x (Bi-2212) Cable-in-Conduit conductor (CICC), YBa 2 Cu 3 O 7-x (YBCO)-twisted stacked-tape cable (TSTC) conductor, and Rutherford cable, we have developed a new test facility for their critical current measurement. The key component of the facility is a 6-T dipole magnet with a useful bore of 80 mm, which is connected through a pair of 6-kA binary-current leads to the external dc power supply. The homogeneous high field length is 400 mm with uniformity better than 98%. Instead of the traditional expensive dc power supply and complicated current leads, a superconducting transformer is used to supply the test sample with current up to 30 kA. Quench detection and protection system are also used for both the primary coil of superconducting transformer and the 6-T dipole magnet. An NbTi Rutherford cable with ten strands has been tested to verify the test facility. The status of our test facility and the test results are described in this paper.

This paper presents a theoretical model that allows to calculate the acoustic transmission loss through laminated composite pyramidal sandwich structure consisting of two parallel plates connected by trusses. First-order shear deformation theory is adopted to model the vibration of such a structure, accounting for in-plane motion and coupling between extension and flexure of the different components, and taking into account elastic anisotropy. The interaction between the structure and the surrounding fluid is taken into account by imposing a velocity continuity condition at the interfaces. The displacement and stress fields are calculated in Fourier domain by solving the set of boundary condition equations at the connecting points. The theoretical predictions for the acoustic transmission through the structure show satisfactory agreement with experimental results of a standing wave tube experiment on specimens that were fabricated by cutting trusses from carbon fiber reinforced composite plates and snap-fitting them to plates made of the same material. Numerical simulations are used to verify, the influence of the stacking geometry and material parameters on the acoustic transmission for different frequencies and angles of incidence. Conclusions are presented that are helpful for practical design.

Extraction columns are one of the important liquid–liquid mass transfer equipment with wide applications in industries like petrochemical, chemical, food, pharmaceutical and so on. Therefore, reliability evaluation and failure analysis plays an important role in safe and normal operation of them. In this study, root causes analysis of localized abnormal wear on the inner wall of one extraction column for manufacturing methyl methacrylate (MMA) was addressed. Based on field investigation, wear surfaces analysis, scales inspection, precision testing and finite element analysis, the results showed that out-of-roundness of the sieve plates and deflection of the main shaft were the root causes. The detailed mechanisms were then discussed, and the pertinent countermeasures were proposed to prevent the recurrence of similar cases.

In this study, a convenient method of preparing the substrate is proposed with one-pot synthesis of silver colloid under body heat, and the SERS detection uses the fresh substrate to avoid the drawback of substrates’ short life of use. The synthesis of silver colloid is carried out in a 10 mL vial by using ascorbic acid as a reductant and trisodium citrate as a stabilizer. The vial is grasped with the palm of the experimenter for several minutes without shaking. The proposed method is simple, rapid, green energy and cost-effective. By adjusting the concentration of trisodium citrate, not only the particle size can be controlled from about 110 nm to 50 nm but also the homogeneity of nanoparticles can be improved. As a SERS substrate, the silver colloid has high batch reproducibility and showed good SERS activity. The relative standard deviation between different manufacturers is 5.51% when the substrate of silver colloid is used for the detection of rhodamine 6 G. Using the substrate, the lowest detection concentrations of rhodamine 6 G, crystal violet, enrofloxacin, melamine and leucomalachite green are 1.0 × 10−8, 6.1 × 10−8, 1.4 × 10-6, 7.1 × 10-5 and 5.1 × 10−8 mol/L, respectively. Results demonstrate that the developed method has the advantage of convenience and high efficiency in the field preparation of reliable SERS substrate.

The study on the spray morphology of effervescent atomization based on the internal gas–liquid flow patterns were conducted by the combination of experiment and numerical simulation methods. Both time-average and fluctuation characteristics of the spray morphology under various internal flow patterns were given out. The analysis on the corresponding relationship between internal flow and spray morphology was further present out. Results showed that the internal flow pattern has little influence on the time-average characteristic of the spray morphology, but takes great effect on the fluctuation characteristics of spray morphology. In churn flow, the spray half cone angle varies in a narrow range. In bubbly flow, the instantaneous spray cone angle pulsates in a wide range. In slug flow, the spray morphological pulsating phenomenon is of polarization, the spray half cone angle distributes mainly in the low or high value ranges decided by whether gas’s contributing to the jet breakup. The instantaneous gas–liquid phase distribution in the exit orifice region and the variation law of gas void fraction at the nozzle exit is the direct cause of the spray morphology.

High-emissivity MoSi2-SiC-Al2O3-SiO2 coating with MoSi2 and SiC as emittance agents, Al2O3 as base skeleton, and silica sol as both dispersive medium of the coating slurry and binder of the coating, was prepared on mullite fibrous insulations via slurry coating and non-firing process. The non-firing coatings were calcined at high temperatures to reveal their reusability after high temperature service. Microstructure, phase composition, interface bonding strength and impact resistance of the non-firing coating and the calcined coatings were investigated comprehensively. Thermal shock resistance, thermal endurance and infrared radiation property of the coatings were studied. The results show that the non-firing coating was dense and flat with all particles bonded together by silica sol; no clear interface existed between the coating and the substrate due to the penetration of the coating slurry; the whole coating was composed of a porous inner layer of about 300 µm in thickness and a top layer of about 100 µm in thickness. The calcined coatings exhibited ideal microstructure with newly formed high temperature phases. Both interface bonding strength and impact resistance of the calcined coatings increased with elevated calcination temperatures, benefited from the good binding effect of silica sol, the gradient structure and the formation of mullite. The coatings remained intact without peeling and spalling after thermal shock tests, and the main defects in the coating surface after thermal shock tests at 1400 °C and 1500 °C were cracks and holes, respectively. The coatings exhibited better long-term thermal endurance at 1400 °C than at 1500 °C, resulted from the weaker oxidation of emittance agents at lower temperature. The emissivity of the non-firing coating at the wavelength range of 3–5 µm and 8–12 µm was as high as 0.9, benefited from the non-firing process, and the emissivity of the calcined coatings were higher than 0.8.

Information security has aroused wide concern in this new era of information; thus, the development of security methods for storing and expressing confidential information is of great importance. Herein, we provided a novel information storage and visual expression device based on mechanoluminescent materials and poly(dimethylsiloxane) using a simple fabrication method. The device could record the region where the stress was applied and store the information and finally express it via light emission under mechanical stimuli. Furthermore, the luminescence properties of the resulting device could be tuned by adjusting the composition of the mechanoluminescent layer or the initially applied stress. More importantly, the as-fabricated device exhibited a fast and sensitive response to the stimuli along with excellent repeatability as well as long-term stability, making it reliable for promising applications in confidential information storage, anti-counterfeiting and secure communication.

Fly ash cenosphere/mullite (FACs/M) composites with excellent high-temperature resistance were prepared through a tert-butyl alcohol gelcasting process, using the mullite and FACs as the matrix and the filler, respectively, and the matrix of mullite was derived from phase transformation of the raw material of kaolin. Results show that the FACs/M exhibited low density and high specific compressive strength and the thermal conductivity was distributed over in the range of values predicted from Maxwell-Eucken model 2 and Effective Medium Theory (EMT) equation. Exponent m describing the relationship between compressive strength and porosity was 2.37. Young’s moduli of the composites were lower than that predicted from the Hashin-Shtrikman model. The high-temperature testing results revealed that the FACs/M composite exhibited high compressive strength and the 50% FACs/M composite displayed compressive strength of 14.11 MPa after testing at 800 °C. The FACs/M composites with excellent mechanical properties both at room and high temperatures may possibly be used in the deep sea and other fields in the near future.

A magnetic sorbent of Ce-doped Fe–Mn sorbent (Fe–Mn–Ce) was synthesized to capture gaseous elemental mercury from coal-fired flue gas. The physical and chemical properties of Fe–Mn–Ce sorbent were characterized by N2 adsorption, vibrating sample magnetometer, X-ray diffraction, transmission electron microscope, and X-ray photoelectron spectroscopy (XPS). The mercury removal capability of Fe–Mn–Ce sorbent was tested in a fixed-bed system, and the effect of flue gas temperature and O2 was investigated. The valence change of Fe 2p, Mn 2p, Ce 3d, O 1s, and Hg 4f on the sorbent surface during mercury removal process was analyzed. Finally, the mechanism of mercury removal by the Fe–Mn–Ce sorbent was explored. The result shows that the synthesized Fe–Mn–Ce sorbent consists of many extremely small nanoparticles, contains a polycrystalline structure, and shows good mercury removal performance. High temperature is beneficial to mercury removal by the Fe–Mn–Ce sorbent, but the 6% O2 in flue gas plays a negligible ro...

The internal flow in an effervescent atomizer was experimentally observed for a wide range of gas–liquid flow rates with various atomizer geometries. The effects of atomizer geometry, gas and liquid flow rates on the flow regime and bubble size were investigated. The results show that the internal flow is significantly affected by exit orifice geometry, aerator location, and fluids flow rates, but less affected by aerator configuration. A high velocity of the liquid, small exit orifice diameter, and large distance between the aerators and the exit orifice are beneficial for the formation of bubbly flow. In bubbly flow, the bubble size decreases with liquid flow rate and gas-to-liquid mass ratio (GLR); it follows a normal distribution, and is less related to the atomizer geometry. At a certain liquid flow rate and GLR, small bubbles are readily formed under the exit orifice with a small diameter and proper length. It is found that there are critical values of GLR and critical mean bubble diameters related to gas–liquid mixing; values above the critical GLR and below the critical mean bubble diameter are beneficial for internal gas–liquid mixing. Based on the results of comparison of internal and external flow, it is possible to improve the spray performance by optimizing the internal flow parameters.

Auxetic materials and structures as a class of metamaterials have been extensively studied and evaluated for many applications. This paper focuses on the fabrication and vibration damping of the carbon fiber composite auxetic double-arrow corrugated sandwich panels (DACSPs). The negative Poisson’s ratio effects of the composite auxetic DACSPs are analytically studied based on energy method. 3D finite element (FE) models combined with Modal Strain Energy (MSE) approach are developed to investigate their vibration and damping characteristics. To validate the numerical models in the present study, the composite auxetic DACSPs and such structures inserted with high damping layer are designed and manufactured. Modal vibration and three-point bending tests are conducted to investigate their vibration damping and bending responses. The results show that the 3D FE models combined with MSE approach are valid to predict the modal properties of the composite auxetic DACSPs. The influence of the different inclined corrugated angles on the natural frequencies and damping loss factors are plotted and discussed. Meanwhile, the effect of Poisson’s ratio on the nominal Young’s modulus, natural frequencies and damping loss factors of the composite auxetic DACSPs are also revealed. It is observed from the results that it is possible to obtain both increased stiffness and high damping capacity of such composite auxetic DACSPs by optimizing the inclined corrugated angles and inserting suitable damping layers.

Oxygen electrodes for oxygen evolution reaction and oxygen reduction reaction were intensively investigated due to high overpotential required to drive the four-electron process. A NiOx@MnOx@G nanostructure supported homogenously on graphene nanosheets through an easy and scalable self-assembly method was studied. The NiOx@MnOx@G exhibited a nanostructured NiOx nanocrystalline with size around 2.3 nm and an amorphous MnOx with controllable thickness. The 25% NiOx@MnOx@G showed remarkable activity for oxygen reduction reaction with a 4-electron process, the half-wave potential was 50 mV, but the stability of 25% NiOx@MnOx@G was better than Pt/C-JM. NiOx@MnOx@G nanostructure exhibited significantly better activity for oxygen evolution reaction compared with MnOx, which can demonstrate that NiOx could tune the activity of surface amorphous MnOx and dramatically increased oxygen evolution reaction activity. NiOx@MnOx@G is demonstrated with superior oxygen catalysts performance for reversible oxygen evolution and oxygen reduction reaction, due to the synergistic effect of NiOx and amorphous MnOx.

High emissivity coatings on fibrous insulation tiles played an important role in thermal protection systems and thereby intrigued many researchers; however, there was little emphasis on the mechanical properties of the coatings. In this study, a gradient MoSi2-borosilicate glass coating with a dense surface layer and a porous interlayer was designed for mullite fibrous ceramics. Mechanical properties and structure parameters of the coating layers and the substrate were studied. The gradient coating was compared with a monolayer dense coating of the same composition and same surface density in contact damage resistance, impact resistance and emissivity. Compared with monolayer dense coating coated substrates, the gradient coating coated ones exhibited two times higher load bearing capacity in Hertzian indentation test at the same displacement of 1 mm; they appeared to be stiffer and harder at constant load of 20 N, and showed better impact resistance at impact energy range of 0.25–0.75 J in the falling weight test; besides, fatal radial cracks were not observed in gradient coatings after the tests. In addition, the gradient coating had higher emissivity (0.838) than the monolayer dense coating (0.816) because of the significant absorptivity increase and reflectivity decrease by small gradual slopes in the rough surface.

numerical simulation was conducted to study the influence of bleeding. The Euler-Lagrange method was used to investigate the two-phase turbulent combustion flow. Standard k-ε turbulent model was adopted in the continuous phase simulation and particle-trajectory model was adopted in the dispersed phase simulation. The results demonstrates: air bleeding can improve the flow field after the strut and the stability of trapped vortex in the cavity; change of bleeding temperature has little effect on the total pressure recovery coefficient and significant effect on combustion efficiency; When fuel-air ratio changes, the combustor performs better in a lean oil state. Keywords: Cavity, Strut, Bleeding, Ramjet combustor, Numerical simulation

Currently, non-centrosymmetric oxychalcogenides, a class of newly developed heteroanionic compounds, have emerged as promising candidates for IR nonlinear optical (NLO) materials due to the fact that they can combine the impressive second-harmonic generation (SHG) responses of chalcogenides with the wide energy gaps of oxides. Moreover, multiple combinations of chalcogens and the oxygen element would, in principle, lead to more new frequency-doubling building units, enabling the extensive seeking and design of new NLO-active oxychalcogenides. In this Frontiers article, the recent developments of oxychalcogenides as IR-NLO candidates are summarized. These materials can be grouped into three types in terms of their structural dimensions: (i) two-dimensional layered CaZnOS, SrZn2OS2, Sr8Ga8O3S14, Sr6Cd2Sb6O7S10 and Sr4Pb1.5Sb5O5Se8; (ii) one-dimensional chain-typed AEGeOQ2 (AE = Sr and Ba; Q = S and Se); and (iii) zero-dimensional molecular Sr3Ge2O4Se3 and α-Na3PO3S. We discuss the rich coordination environment of mixed-anion frequency-doubling building units focusing on the correlations between their non-centrosymmetric structures and NLO properties, as well as their synthetic methods. Finally, the present challenges and future perspectives in this field are also proposed.

Electrosynthesis of formic acid/formate is a promising alternative protocol to industrial processes. Herein, a pioneering pair-electrosynthesis tactic is reported for exclusively producing formate via coupling selectively electrocatalytic methanol oxidation reaction (MOR) and CO2 reduction reaction (CO2 RR), in which the electrode derived from Ni-based metal-organic framework (Ni-MOF) nanosheet arrays (Ni-NF-Af), as well as the Bi-MOF-derived ultrathin bismuthenes (Bi-enes), both obtained through an in situ electrochemical conversion process, are used as efficient anodic and cathodic electrocatalysts, respectively, achieving concurrent yielding of the same high-value product at both electrodes with greatly reduced energy input. The as-prepared Ni-NF-Af only needs quite low potentials to reach large current densities (e.g., 100 mA cm-2 @1.345 V) with ≈100% selectivity for anodic methanol-to-formate conversion. Meanwhile, for CO2 RR in the cathode, the as-prepared Bi-enes can simultaneously exhibit near-unity selectivity, large current densities, and good stability in a wide potential window toward formate production. Consequently, the coupled MOR//CO2 RR system based on the distinctive MOF-derived catalysts displays excellent performance for pair-electrosynthesis of formate, delivering high current densities and nearly 100% selectivity for formate production in both the anode and the cathode. This work provides a novel way to design advanced MOF-derived electrocatalysts and innovative electrolytic systems for electrochemical production of value-added feedstocks.

The electrochemical hydrogen evolution reaction (HER) is an attractive technology for the mass production of hydrogen. Ru-based materials are promising electrocatalysts owing to the similar bonding strength with hydrogen but much lower cost than Pt catalysts. Herein, an ordered macroporous superstructure of N-doped nanoporous carbon anchored with the ultrafine Ru nanoclusters as electrocatalytic micro/nanoreactors is developed via the thermal pyrolysis of ordered macroporous single crystals of ZIF-8 accommodating Ru(III) ions. Benefiting from the highly interconnected reticular macro-nanospaces, this superstrucure affords unparalleled performance for pH-universal HER, with order of magnitude higher mass activity compared to the benchmark Pt/C. Notably, an exceptionally low overpotential of only 13 mV@10 mA cm

In this paper, a model based on the T-A formulation and continuous approximation method have been developed. With this model, the current distribution at energized state and the central field error of the 11 T REBCO insert coil (without background field) at different ramping rates was numerically simulated and analyzed. Based on the numerical results, it can be inferred that the screening current effect and magnetic field penetration depth on each single pancake are related to its position in the coil, and the current density on the single pancake near the middle of the insert coil is more uniform. In addition, the central field error is not affected by the ramping rate of the insert coil.

Magnetic binary heterojunctions are a kind of promising photocatalysts due to their high catalytic activity and easy magnetic separation; however, their synthesis may involve high costs or secondary environmental impacts. In this work, the magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn1-xMnxS (MZFO@Zn1-xMnxS, x = 0.00–0.07) photocatalysts are synthesized from spent batteries via a green biocheaching and egg white-assisted hydrothermal method. The as-synthesized photocatalysts have been comprehensively characterized in phase, morphology, texture, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that the desired core-shell structure MZFO@Zn1-xMnxS composites are successfully synthesized, theirs absorption intensity in the visible light region is greatly enhanced compared to Zn1-xMnxS. In addition, doped Mn2+ in ZnS host lattice and the staggered bandgap alignment of MZFO and Zn1-xMnxS greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@Zn0.95Mn0.05S shows the highest photodegradation performance toward phenol under the visible light irradiation, with a complete degradation of 25 mg L−1 of phenol within 120 min, and its reactive kinetic constants is about 5.2 and 13.3 times higher than that of pure Zn0.95Mn0.05S and MZFO, respectively. Furthermore, the mechanism and pathways for the degradation of phenol are proposed. In addition, MZFO@Zn0.95Mn0.05S also exhibits a good reusability and high magnetic separation properties after 5 successive cycles. This new material has the advantages of low costs, simple reuse and great potential in application.

The second harmonic generation (SHG) responses of nonisostructural nonlinear optical (NLO) compounds, β-BaB2O4, LiB3O5, CsB3O5, CsLiB6O10, KBe2BO3F2, and LiCs2PO4, were examined by density functional theory (DFT) calculations, and the contributions of their individual cations and anions were determined by performing atomic response theory analyses. In all of these compounds, the contribution of all metal cations lies in the range of ∼9.3 to ∼29.7% of the total SHG responses, and that of all anions lies between ∼57.4 and ∼72.3%. However, in terms of individual atom contribution, a large metal cation can contribute more than does an anion to the total SHG response. Our work shows that the SHG contribution of an individual anion (e.g., O2-) is weakened when it forms covalent bonds with its surrounding cations (e.g., O-B). The contribution of an individual cation is further affected by the homogeneity of its surrounding anion distribution and also by how strongly the polarizabilities of its surrounding anions are weakened by covalent bonding with other cations. The SHG response increases with αsum/(NEg), an important parameter useful in searching for new NLO materials, where αsum is the sum of the polarizabilities of all of the ions in the primitive unit cell, N is the total number of atoms per primitive cell, and Eg is the band gap.

A new theoretical model is established to study the breakup of a charged power-law liquid jet, which is moving in coaxial swirling air. The liquid non-Newtonian behavior is explained by the power-l...

In recent years, 3D structures with negative Poisson's ratio (auxetic) have attracted great interest. Many polymer and metal 3D auxetic structures have been manufactured using additive manufacturing technology, however composite 3D auxetic structures are rarely reported. Auxetic structures are normally of low stiffness which causes limitations on the structural applications of them. The specific stiffness and strength of auxetic structures can be significantly improved by making them from high-performance fibre reinforced polymer (FRP) composites. Consequently, research of composite 3D auxetic structures made from FRP should be conducted. This paper presents the composite 3D double-arrow-head (DAH) auxetic structure made from carbon fibre reinforced polymer (CFRP) using an assembly method. Experimental, finite element and theoretical methods are adopted to study the mechanical properties of the composite 3D DAH auxetic structures. Results show that the Poisson's ratios and effective compression moduli of the composite 3D DAH auxetic structures vary depending on the compression strain amplitude, and the structures become more auxetic and stiffer with the increase of the compression strain. The specific stiffness of the composite 3D DAH structure is much higher than that of the metal structure. In addition, the dependences of the structure's Poisson's ratio and effective compression modulus on the geometry parameters have also been given. Making auxetic structures from high-performance FRP composites can significantly improve their mechanical properties which will enable them to have a much wider variety of applications.