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Graphitic carbon nitride (g-C3N4) with transition metal phosphides has been studied extensively as potential photocatalysts for hydrogen evolution. However, in-situ approaches to realize intimate interfacial contacts have rarely been reported. In this study, Ni2P nanoparticles-decorated g-C3N4 photocatalysts were prepared via liquid exfoliation of g-C3N4 followed by in-situ loading of Ni2P nanoparticles in a rotating packed bed (RPB) reactor. The optimized Ni2P/g-C3N4 exhibits high performance in visible-light-driven (λ > 420 nm) hydrogen evolution (∼561 μmol g−1 h−1), which is 103 times higher than that of pristine g-C3N4. The superior photocatalytic performance and durability originate from the robust interfacial structure. Therefore, a Z-scheme route with enhanced transfer of photoinduced electron was proposed, and Ni2P/g-C3N4 composites with smaller bandgaps than those of g-C3N4 were realized. Due to the intensified mass transfer and mixing of RPB reactor, the adsorption and nucleation processes of Ni2P on g-C3N4 were enhanced, enabling scalable solar light-driven H2 production.

The rotating packed bed (RPB) has been widely used in gas-liquid flow systems as a process intensification device, exhibiting excellent mass transfer enhancement characteristics. However, the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods. In the past two decades, Computational Fluid Dynamics (CFD) has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design. This article covers the development of the CFD simulation of gas-liquid flow in RPB. Firstly, the improvement of the simulation method in the aspect of mathematical models, geometric models, and solving methods is introduced. Secondly, new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed, including pressure drop, velocity distribution, flow pattern, and concentration distribution, etc. Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works. In addition, the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications. The defects of current research and future development directions are also discussed at last.

It had been researched the thermal conductivity and dielectric properties of high thermal conductive (HTC) main insulation for the large and medium generator stator bars. The thermal conductivity was analyzed by orthogonal test for the adhesive composed of BN powders and Tung-maleic-anhydride epoxy resin, and the BN with different particle sizes were used in the adhesive. It analyzed the variation of thermal conductivity for the adhesive composite with different BN powder contents, and the best thermal conductivity in the adhesives was 2.27 W/(m K). The variation of the dielectric properties was analyzed for the HTC adhesive by frequency-domain spectrum. It was detected by scanning electron microscope for the dispersion of the BN particles in TAEP and the bond state between the BN particles. The results indicated that the thermal conductivity of the best adhesives was increased by 13 times, and the other properties were almost the same as that of TAEP. Therefore, the HTC adhesive could be used in the main insulation of the large generator stator bars.

It is of great significance for polymers used in electrical systems to maintain insulation property while improving the thermal conductivity of them. In order to achieve this goal, this paper used hexagonal boron nitride (h-BN) and a small amount of carbon nanofibers (CNF) as filling phase, prepared thermally conductive insulating dielectric materials based on epoxy. An effective heat transport network is formed in the material by the synergistic effect of the two-dimensional structure of h-BN and the one-dimensional structure of CNF, thereby improving the thermal conductivity of the composite materials. The thermal conductivity of the composite with the filling amount of 20 phr h-BN & 0.001 phr CNF reached 0.505 W/(m K), which is 188.6% higher than that of pure epoxy. At the same time, the composites also exhibited higher insulating strength under DC conditions and lower tangent of the dielectric loss angle in a wide frequency range. This simple mixing strategy provides a new way for the preparation and research of thermally conductive and insulating polymer materials.

Wave-based active vibration control of a membrane structure by using the Active Sink Method is studied in this paper. Unlike the modal-based vibration control method which attempts to suppress several vibration modes that have already been excited, wave-based active controller can keep vibration modes inactive by stopping the formation of standing waves in the structure. First, the wave transfer matrix is deduced to characterize the wave transmission in the membrane structure. Then, feedforward wave control laws are derived analytically to absorb reflected waves or eliminate transmitted waves. The validity of the proposed active wave controllers is verified through numerical simulations. Simulation results show that by using the active wave controllers no standing waves will be produced in the structure, and the vibration of the membrane structure is suppressed significantly.

Generally, the high-temperature performance of martensitic heat-resistant steels is limited by the content of δ-ferrite and the degradation of precipitates. Herein, a 9Cr high-nitrogen heat-resistant martensitic steel (HNHMS9) with 0.3 wt.% N was designed and prepared due to the high stability of nitride precipitates. Furthermore, its microstructure evolution was investigated, correlated to heat treatments. HNHMS9 normalized at 1200 °C and tempered at 760 °C exhibited more δ-ferrite, while HNHMS9 normalized at 1050 °C and tempered at 760 °C contained less δ-ferrite and massive strip-like coarse nitrides. Interestingly, the former HNHMS9 exhibited higher ductility than, but similar strength to, the latter at elevated temperature, although δ-ferrite is typically regarded as a detrimental phase for the strength and impact toughness of heat-resistant steels. Thus, an efficient strategy proposed for heat treatment of HNHMS9 is that it is preferable to eliminate strip-like coarse nitrides by insulation at elevated temperature despite the increased δ-ferrite content.

MnZn ferrites and their magnetic, electrical, and optical properties make them highly suitable in a number of applications. These ferrites are used in electronic applications, magnetic fluids, and household appliances such as washing machines, refrigerators, and microwave ovens. This paper focuses on a hydrothermal method used to prepare a bayberry spherical manganese–zinc ferrite (Mn0.5Zn0.5Fe2O4), its surface was coated with dopamine (Mn0.5Zn0.5Fe2O4@PDA) and then carbonized to obtain the core–shell structure C-Mn0.5Zn0.5Fe2O4@PDA. Preliminary results show that carbon-coated manganese–zinc ferrite with saturation magnetic properties and coercivity increased from 99 emu and 66.01 Oe to 138 emu and 104.85 Oe, respectively. In addition, the carbonized Mn0.5Zn0.5Fe2O4@PDA (C-Mn0.5Zn0.5Fe2O4@PDA) exhibited favorable microwave absorbing performance with minimum reflection loss (RLmin) of − 17.56 dB and also revealed that the broadest effective absorption bandwidth (RLmin ≤ − 10 dB) 5.36 GHz (11.70–17.06 GHz) can be achieved at 2.0 mm.

This study investigated the microstructures and properties of deposits protected by seven different proportions of N2 and Ar by performing wire-arc additive manufacturing of the 5356 aluminium alloy. The results show that when the proportion of N2 in the shielding gas was larger than and equal to 50%, flaky nitrides were generated in the deposits. With an increase in the proportion of N2 in the shielding gas, the number and size of nitrides in the deposits as well as the fluctuation frequency and amplitude of the microhardness of the deposits all increase. The existence of flaky nitrides incurs a low ultimate tensile strength of additively manufactured parts protected by a mixed gas containing N2. The presence of large-size flaky nitrides between layers in the deposits leads to a large difference in tensile properties in the horizontal and vertical directions of the deposit. Tensile fracture shows that the deposits were fractured in the mixed mode of ductile and brittle fracture.

Heat resistance is a basic and crucial characteristic of energetic materials (EMs), and always accounted in development and application. Compared with the clear origin of the high heat resistance of EMs, the mechanism for the low heat resistance remains still unclear. This work reveals the mechanism by carrying reactive molecular dynamics simulations on heating six less thermally stable EMs of nitroforms and pentaerythritol tetranitrate (PETN), as well as a more thermally stable EM of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) for comparison. Unexceptionally, all the nitroforms and PETN heated feature fast NO2 partition and further decomposition throng the oxidation of NO2 to form small fragments and final small stable product molecules, with fast heat release; while, the intermolecular reactions and the further clustering govern the initial steps in decomposing TATB. Therein the reactants also exhibit a rapid consumption; however, this fast consumption with clustering does not result in the low heat resistance of TATB. That is, some general indicators representative of thermostability, such as bond dissociation energy and the reactant consumption rate, are insufficient to assess it practically. Thus, the rapid fragmentation originally contributes to the low heat resistance. These insights are expected to present an overall perspective of understanding the thermal stability mechanism of EMs, and set a theoretical base and pave a way for designing EMs with desired heat resistance.

Low-dimensional semiconductors have shown great potential in switches for their atomically thin geometries and unique properties. It is significant to achieve new tunneling transistors by the efficient stacking methodology with low-dimensional building blocks. Here, we report a one-dimensional (1D)-two-dimensional (2D) mixed-dimensional van der Waals (vdW) heterostructure, which was efficiently fabricated by stacking an individual semiconducting carbon nanotube (CNT) and 2D MoS2. The CNT-MoS2 heterostructure shows specific reconfigurable electrical transport behaviors and can be set as a nn junction, pn diode, and band-to-band tunneling (BTBT) transistor by gate voltage. The transport properties, especially BTBT, could be attributed to the electron transfer from MoS2 to CNT through the ideal vdW interface and the 1D nature of the CNT. The progress suggests a new solution for tunneling transistors by making 1D-2D heterostructures from the rich library of low-dimensional nanomaterials. Furthermore, the reconfigurable functions and nanoscaled junction show that it is prospective to apply CNT-MoS2 heterostructures in future nanoelectronics and nano-optoelectronics.

Molybdenum (Mo) and its alloy have great potential in the nuclear power field, but the low strength of fusion welding joints limits its engineering application. By adding two alloying elements in combination, namely carbon (C) and titanium (Ti), this study fulfilled the goal of improving properties of the heat affected zone (HAZ) while strengthening the fusion zone (FZ) of the joint. The alloying process is as follows: the base metal (BM) was first carburized then Ti foil was preset at the welding position and finally laser welding was carried out. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD) and nanoindentation were utilized to analyze mechanical properties and microstructures of the FZ and HAZ of the joint obtained by combined alloying with C and Ti. Moreover, the joint obtained by combined alloying was comparatively analyzed with those alloying only by C or Ti. Combined alloying can increase the maximum tensile strength to 406.6 MPa and strain to 6.6%, respectively. TiC phases as spherical particles with diameter ranging from tens to one hundred of nanometers can be precipitated in the FZ obtained by combined alloying playing a role of second-phase strengthening in Mo. Furthermore, Mo2C phases can be clearly observed at the grain boundary in the HAZ of the joint obtained by combined alloying. Mo2C is coherent or semi-coherent with the Mo matrix and can also have the second-phase strengthening effect. Combined alloying shows a new idea to strengthen Mo and its alloy welded joints.

Molybdenum (Mo), with its high chemical stability and resistance to neutron irradiation, has wide application prospects in the nuclear industry; however, the embrittlement of welded Mo joints limits its further application. In this study, the brittleness of the welded joints of Mo alloy was reduced and their strength was enhanced by adding carbon to the fusion zone (FZ) during laser welding. In the FZ of the Mo joints, carbon mainly existed as Mo2C, and some free C atoms, and MoC and MoOxCy phases were also present. The distribution of Mo2C directly influenced the bonding strength of the grain boundaries. As Mo2C was dispersedly distributed as particles or discontinuous lines at the grain boundaries of Mo, it improved the resistance of the grain boundaries to the propagation of cracks and thereby increasing their strength. However, the Mo2C phases distributed in a reticular pattern at the grain boundaries of Mo provided channels that enabled cracks to rapidly propagate, thereby reducing the resistance of the grain boundaries to crack propagation and weakening their strength. The emergence of the MoOxCy phase reduced the weakening effect of free oxygen atoms on the strength of grain boundaries of Mo.

Dielectric polymer capacitors are extensively applied in advanced electronics by virtue of their extremely high power density. However, it remains a challenge to concurrently realize high energy density and high discharge efficiency. In order to solve this conundrum, we herein design a novel all-polymer trilayer structure, where the paraelectric poly(methyl methacrylate) (PMMA) is used as the top layer to obtain a high discharge efficiency, and ferroelectric P(VDF-HFP) is employed as the bottom layer to obtain a high energy density. Particularly, the PMMA/poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) blend composite is used as the middle layer to homogenize the electric field inside the trilayer composites, turning out an obviously boosted breakdown strength and elevated energy density. Consequently, an efficiency as high as 85% and an energy density up to 7.5 J/cm3 along with excellent cycling stability are simultaneously realized at an ultrahigh electric field of 490 kV/mm. These attractive characteristics of the all-polymer trilayer structure suggest that the feasible pathway presented herein is significant to realize concurrently a high energy density and discharge efficiency.

To realize efficient atmospheric CO2 chemisorption and activation, abundant Ti3+ sites and oxygen vacancies in TiO2 ultrathin layers were designed. Positron annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti3+ sites, giving a Ti3+-Vo-Ti3+ configuration. The Ti3+-Vo-Ti3+ sites could bond with CO2 molecules to form a stable configuration, which converted the endoergic chemisorption step to an exoergic process, verified by in-situ Fourier-transform infrared spectra and theoretical calculations. Also, the adjacent Ti3+ sites not only favor CO2 activation into COOH* via forming a stable Ti3+-C-O-Ti3+ configuration, but also facilitate the rate-limiting COOH* scission to CO* by reducing the energy barrier from 0.75 to 0.45 eV. Thus, the Ti3+-Vo-TiO2 ultrathinlayers could directly capture and photofix atmospheric CO2 into near-unity CO, with the corresponding CO2-to-CO conversion ratio of ca. 20.2%.

The exothermic combustion characteristics of coke play a direct and essential role in artificial ignition and the stability of the combustion front during the heavy oil in situ combustion (ISC) pro...

Anticipation of the critical cutting condition for the transition of continuous chip to serrated chip is a fundamental task in machining of ductile metallic material. In this study, the variation of the dynamic yield stress with the increase of cutting speed was utilized as the criterion to predict the critical cutting condition for onset of the serrated chip. In order to accurately and conveniently determine the value of dynamic yielding strength of the workpiece material during the cutting process, an improved Williams’ model in conjunction with a 2D orthogonal slot milling test is proposed. Two typical ductile metals of silicon brass and Ti6Al4V were used as the workpiece material in this framework. Also, the chip morphology obtained in cylindrical turning test was used to validate the predicted results. For the two workpiece materials tested, it is observed that the error between the predicted result and the experimental result is always lower than 12%. The proposed methodology in this work exhibits its superiority in terms of calculation and predicting efficiency, which is still a challenge for traditional analytical method and finite element method.

This study investigated the effects of post-weld heat treatment (PWHT) on microstructures and properties of a laser welded joint of high-strength and high-toughness titanium alloy, namely Ti-5Al-5V-5Mo-3Cr-1Zr (Ti-55531). The experimental results demonstrate that PWHT can improve the tensile strength of the joint by 47.8 %, which reaches 92.4 % of base metal (BM). Average microhardness of a weld metal (WM) of the joint increases from 309 HV in the as-welded state to 371 HV. The analysis shows that PWHT can significantly improve microstructures of the joint, which is an important reason for rising strength of the joint. The BM of the as-welded joint presents a typical duplex microstructure and 10∼20 % of equiaxed αp phases are inserted into fine transformed β microstructures. Equiaxed grains are retained in a heat affected zone (HAZ) and the WM is composed of coarse columnar grains. After PWHT, there is no obvious change in microstructures of the BM of the joint. While maintaining β phases in BM, the edge of equiaxed α phases in the HAZ gradually dissolves and change to the WM microstructure. In the WM, microstructures change the most significantly and a lot of acicular α phases appear.

The enrichment and focusing of the nano-/submicroparticle (e.g., 150-1000 nm microvesicle shed from the plasma membrane) in the viscoelastic fluid has great potentials in the biomedical and clinical applications such as the disease diagnosis and the prognostic test for liquid biopsy. However, due to the small size and the resulting weak hydrodynamic force, the efficient manipulation of the nano-/submicroparticle by the passive viscoelastic microfluidic technology remains a major challenge. For instance, a typically long channel length is often required to achieve the focusing or the separation of the nano-/submicroparticle, which makes it difficult to be integrated in small chip area. In this work, a microchannel with gradually contracted cross-section and high aspect ratio (the ratio of the height to the average width of channel) is utilized to enhance the hydrodynamic force and change the force direction, eventually leading to the efficient enrichment of nano-/submicroparticles (500 and 860 nm) in a short channel length (2 cm). The influence of the flow rate, the particle size, the solid concentration, and the channel geometry on the enrichment of the nano-/submicroparticles are investigated. With simple structure, small footprint, easy operation, and good performance, the present device would be a promising platform for various lab-chip microvesicle-related biomedical research and disease diagnosis.

The self-assembly of biomacromolecules is an extremely important process. It is potentially useful in the fields of life science and materials science. To carry out the study on the self-assembly of proteins, it is necessary to find out the suitable self-assembly conditions, which have always been a challenging task in practice. Inspired by the screening technique in the field of protein crystallization, we proposed using the same screening technique for seeking suitable protein self-assembly conditions. Based on this consideration, we selected 5 proteins (β-lactoglobulin, hemoglobin, pepsin, lysozyme, α-chymotrypsinogen (II) A) together with 5 screening kits (IndexTM, BML, Morpheus, JCSG, PEG/Ion ScreenTM) to investigate the performance of these crystallization screening techniques in order to discover new optimized conditions of protein self-assembly. The screens were all kept at 293 K for certain days, and were analyzed using optical microscope, scanning electron microscope, transmission electron microscope, atomic force microscope, fluorescence microscope, and atomic absorption spectroscope. The results demonstrated that the method of protein crystallization screening can be successfully applied in the screening of self-assembly conditions. This method is fast, high throughput, and easily implemented in an automated system, with a low protein consumption feature. These results suggested that such strategy can be applied to finding new conditions or forms in routine research of protein self-assembly. KEY POINTS: • Protein crystallization screening method is successfully applied in the screening of self-assembly conditions. • This screening method can be applied on various kinds of proteins and possess a feature of low protein consumption. • This screening method is fast, high throughput, and easily implemented in an automated system.

Developing high-efficiency and low-cost electrocatalyst is significant for the application of water splitting technology. Herein, Co3O4 nanoparticles and MnO2 nanosheets are separately synthesized and subsequently assembled into a unique 0/2-dimensional heterostructure via van der Waals interactions. The consequent composites expose abundant accessible active sites and expedite the reaction kinetics, which can be testified by the superiorities in Tafel slope, exchange current density and double-layer capacitance, only requiring overpotentials of 355 and 129 mV for oxygen and hydrogen evolution reactions in 1.0 M KOH at 10 mA cm−2, respectively. Moreover, a cell voltage of 1.660 V can drive the electrolyzer at 10 mA cm−2. Benefitted from robust integration, the original aggregation and restacking of individual materials have been overcome, thereby leading to superior elelctrocatalysis durability. This facile and universal strategy may inspire the researchers on the design and construction of advanced functional composites.

Highly thermostable energetic materials (EMs) are highly desired for deep underground and space exploration, and therefore have attracted much attention. This work employs four typical traditional EMs composed of C, H, N and O atoms as example to clarify the origin of high heat resistance, by means of molecular dynamics simulations with the molecular reactive forcefield of ReaxFF. These EMs include 3,5-dinitro-N,N´-bis(2,4,6-trinitrophenyl)pyridine-2,6-diamine (PYX), 1,3,5-diamino-2,4,6-trinitrobenzene (TATB) and 2,2´,4,4´,6,6´-hexanitrostilbene (HNS), which are highly thermostable with decomposition temperature peaks > 600 K, and a less one of pentaerythritol tetranitrate (PETN) for comparison. It is found that the clustering in the decomposition of PYX, TATB and HNS retards the extraction of small product molecules from clusters, as well as heat release, and thereby roots for their high heat resistance; while, the clustering in the PETN decay is negligible and heat release and fragmentation proceed rapidly, facilitating to fast decomposition. Combining this finding with the well-known molecular stability, this work presents a perspective on the high heat resistance of traditional EMs. Based on it, a highly negative oxygen balance, a high C content and a high molecular stability are proposed as a strategy for designing and constructing new highly heat-resistant EMs.

Energetic additives can effectively increase the heat release of ammonium perchlorate (AP) decomposition to prevent nonenergetic additives from decreasing the energy density of composite solid prop...

Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed, featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor. When combined, the two components can undergo visible light-induced single-electron transfer, and serve as a versatile and effective alkyl radical generator.

Free-standing Pt-Ni nanowires were fabricated by a one-pot solvothermal method. Nanowires with an optimal Pt/Ni ratio of 1.86 exhibited a high activity and a 100% H2 selectivity for hydrous hydrazine decomposition at mild temperatures, which are comparable to the levels of supported catalysts. Our study reveals for the first time that basic support is not a prerequisite for achieving favorable catalytic performance and provides a renewed perspective for the design of advanced catalysts for on-demand H2 generation from hydrous hydrazine.

Zeolite membranes with unique physical and chemical properties are emerging as attractive candidates for membrane separation. However, defects in the zeolite layer seriously affect their molecular sieving performance. In this study, a novel strategy for preparing compact zeolite membranes on rough supports with the assistance of a reticulated hydrotalcite layer was developed. The reticulated hydrotalcite layer was grown on the inner surface of a 170 mm length ceramic tube by an in situ hydrothermal method, and a NaA zeolite membrane was prepared on this reticulated layer by the microwave-heating method. The hydrotalcite interlayer could not only improve the smoothness and regularity of the surface of the support but also fix the Si/Al active ingredients using its reticulate structure, finally effectively improving the quality and stability of the zeolite layer. The optimal molar ratio of the synthesis solution for the synthesis of the zeolite membrane was 3Na2O : 2SiO2 : Al2O3 : 200H2O. The permeance flux of H2 through the zeolite membrane synthesized under the optimal conditions was high as 0.47 × 10−6 mol m−2 s−1 Pa−1, and its permselectivity for H2 over N2 was 4.7, which was higher than the corresponding Knudsen diffusion coefficient. This study provides a new idea for the preparation of defect-free membranes on rough supports.

With the rapid development of miniaturization and high integration of electronic devices, increasing attention has been paid to the exploration of dielectric composites with further improved dielectric permittivities. Herein, a unique design of high dielectric permittivity composites consisting of three-dimensional porous W-WO3/BaTiO3 foams hosted in epoxy matrix is proposed. It is demonstrated that the introduction of W-WO3/BaTiO3 foams into the epoxy matrix results in substantially improved dielectric permittivities in comparison with the epoxy matrix. Meanwhile, low loss which is comparable to that of the epoxy matrix is well maintained. Interestingly, obviously enhanced dielectric permittivities and greatly depressed loss are concurrently achieved via increasing the oxidation temperature. In particular, the composite with 53.1 wt% W-WO3/BaTiO3 foam oxidized at 1300 °C exhibits a high dielectric permittivity of ~ 536 and a low loss tangent of ~ 0.05@10 kHz which are about 149 and 1.5 times those of the epoxy matrix, respectively. It is believed that the strong interfacial polarization and the numerous equivalent micro-capacitors result in the significantly improved dielectric permittivities. The finite element simulation results reveal that the formation of the WO3 shell on the surface of W can effectively weaken the leakage current density, yielding the sharply depressed loss. This work provides a new strategy to design polymer composites with simultaneous high dielectric permittivity and low loss, and the strategy could also be applicable to the exploration of other high-performance dielectric composites.

Calcium cobaltite Ca3Co4O9+δ in a single-crystal form was reported with an extrapolated dimensionless thermoelectric figure of merit of 0.87 in the year 2003. Regardless of the intensive effort dur...

The microstructure characteristics and properties (especially hole expansion property) of 800 MPa hot-rolled complex phase steel with different coiling temperatures were studied. The microstructure consisted of polygonal ferrite and precipitates when the steel was coiled at 550 °C, and when the steel was coiled between 460–520 °C, the microstructure was composed of granular bainite and martensite and austenite (M/A) islands. The morphology of the crack was analyzed by scanning electron microscopy, and the in situ scanning electron microscope tensile test was used to find out the fracture mechanism and deformation behavior of the steel with different coiling temperatures. When the steel was coiled at 550 °C, the cracks initiated at the ferrite grain boundary and propagated through the grains or along the grain boundaries. When the steel was coiled at 520 °C, the cracks first initiated at the junction of ferrite and M/A island and then propagated through the grains. The steel coiled at 520 °C has quite good mechanical properties and relatively high hole expansion ratio.

As one of the most abundant materials on earth, SiO2 has a broad prospect in the application of lithium ion batteries due to its high specific capacity, low cost and environmental friendliness. However, the low electrical conductivity and large volume variation during charging and discharging lead to the serious performance degradation of SiO2. In this paper, we synthesized a 1/2D hierarchical material, in which SiO2 nanotubes were uniformly anchored on the surface of reduced graphene oxide through electrostatic self-assembly, and it delivers a high discharge capacity of 961 mAh g−1 at the current density of 200 mA g−1 after 250 cycles. At a high current density of 5000 mA g−1, it still shows a decent discharge capacity of 378 mAh g−1 after 2000 cycles, drawing parallels to that of commercial graphite. The excellent performance is mainly attributed to the nanotube structure of SiO2 and its uniform distribution on rGO by electrostatic self-assembly.

Optimal high pressure is crucial to the performance of transcritical CO2 heat pump water heater (HPWH). From the perspective of refrigerant charge management, this work aims to approach optimum COP in CO2 HPWH without high pressure control. By modeling a running CO2 HPWH, we in-depth investigated the relation between optimal high pressure and refrigerant charge. It was found that the essence of optimal high pressure control is to manage optimum refrigerant charge of the system. If the optimum charge of the system could remain constant under any working conditions, the system would operate automatically at optimum COP with fixed refrigerant charge. Then influences of water inlet temperature, water outlet temperature and ambient temperature on optimum refrigerant charge were numerically analyzed. Finally, system design methods to approach optimum COP by minimizing the variation of optimum charge under variable operating conditions were developed. As a result, the average COP loss of fixed-charge system after resizing heat exchangers is only −0.8%. By comparison, with a high-pressure reservoir at the outlet of gas cooler, the average COP loss can be as low as −0.2%.

Olivine-structure LiFePO4 is considered as promising cathode materials for lithium-ion batteries. However, the material always sustains poor electron conductivity and restricted lithium-ion diffusion channel, severely hindering its further commercial application. In this work, adjusting the synthesis condition on pH value is a practical approach to reduce the nanoparticle size, which vastly boosts its performance. The pH = 6 sample exhibits the highest specific capacity (149.7 mAh/g at 0.1 C) and capacity retention (96.3% after 50 cycles at 0.1 C, 89.7% after 200 cycles at 1 C) among the other LiFePO4/C powders. Compared to pH = 8 electrode, cyclic voltammetry and electrochemical impedance analysis disclose the reduced charge transfer resistance from 1492 to 993 Ω. Lithium-ion diffusion coefficient from 1.13 × 10–14 to 4.24 × 10–14 cm2s−1suggests that the optimal pH value can effectively minimize particle size, improve contact area, and buffer the diffusion barrier, including electron and ion, thus including the electrochemical property. Our study provides a simple and efficient strategy to design and optimize promising olivine-structural cathodes for lithium-ion batteries.

Wire mesh packing has been extensively utilized in laboratory and industry applications in rotating packed bed (RPB) because of the high mass transfer performance and low cost. Conventional wire me...

The effect of hyperbaric environment on fiber laser spot welding (LW) of 304 stainless steel was explored. The laser power was 3 kW, the welding time was 0.2 s, and the defocus distance was 0 mm. When ambient pressure rose from 1 to 18 standard atmospheric pressures (atm): the intensity of spectrum signals of plasma above molten pool increased; the number of nano-sized metallic particles inside the beam path grew; in the initial stage of welding, the growth rates of the depth of molten pool and the height of plasma plumes separately reduced to be about 9.1 % and 40 % of those under 1 atm; the weld penetration was decreased to 20 % of that under 1 atm; on condition that the ambient pressure rose to 12 atm from 1 atm, the size of plasma plumes and the intensity of spectrum signals from plasma increased while the weld penetration declined. The main physical mechanism causing reduction of energy density when laser beams went through beams of nano-sized metallic particles was the absorption effect of nano-sized particles rather than their scattering effect. The results also showed that plasma plumes decreased after applying side assisting gas (AS) flow, and they were obviously deviated from the laser beam path, thus increasing the weld penetration to some extent.

Lean duplex stainless steel UNS S32101 was welded by hot wire TIG welding and traditional TIG welding, and nice formed welds with no visible defects were obtained. Metallographic microstructure, phase ratio, mechanical properties and pitting corrosion resistance property of the welded joints were tested. Microstructure analysis showed that the hot wire TIG and traditional TIG welded joints had similar microstructures. The welded metal was composed of ferrite, grain boundary austenite (GBA), Widmanstatten austenite (WA), intragranular austenite (IGA). The high temperature heat affected zone (HTHAZ) consisted of ferrite, GBA and IGA. The low temperature heat affected zone (LTHAZ) had semblable microstructures with base metal. The phase ratio of welded joints was measured by manual point count method. The ferrite/austenite ratio of hot wire TIG welded metal was close to 1:1. The welded joints of hot wire TIG and traditional TIG had same hardness distribution. The hardness of hot wire TIG with an average value of 291 HV10 was a little higher than that of traditional TIG with an average value of 280 HV10. Charpy impact test at -40°C showed that the impact values of hot wire TIG and traditional TIG welded joints meet the standard requirements. The results of chemical weight loss method showed that the corrosion rate of hot wire TIG welded joint was less than 10 mdd. Potentiodynamic polarization method results showed that the pitting corrosion resistance of hot wire TIG welded joints was slightly lower than that of base metal. Solid solution treatment significantly increased the pitting corrosion resistance of welded joints and base metal. The hot wire TIG and traditional TIG had similar microstructure and properties under the same arc power, however the welding speed of hot wire TIG was 1.5 times higher than that of traditional TIG and the welding efficiency was greatly improved.

The tensile deformation process and dislocation behavior of primary α-Ti of Ti-6Al-4V were studied by the in-situ tensile test combined with EBSD (electron backscatter diffraction). The initiation, evolution and distribution of dislocation slips at different strains were discussed. The results showed that the microtexture of the material had a significant influence on slip behavior. Typically, basal and prismatic slips initiated first, but the dominant slip type was related to the local texture characteristics. Sometimes, the basal and prismatic slips could still initiate when their Schmid factors were relatively low, while the pyramidal slips usually need a higher Schmid factor to initiate. With the increase of strain, the second slip system inside one grain was activated to accommodate the plastic deformation. When the deformation was localized in a specific microtextured region, basal slips were dominant, but eventually the crack initiated from the slip bands inside the grain.

This work presented experimental and modeling studies on the simultaneous absorption of H2S and CO2 into the N-methyldiethanolamine (MDEA) and piperazine (PZ) solution in a rotating packed bed (RPB...

Spent caustic from the desulfurization of liquefied petroleum gas has been proved to be effectively regenerated in a rotating packed bed (RPB) with classic wire mesh packing. However, the influence of the packing’s surface wettability on regeneration performance in the RPB was not clear with this oil-water two-phase system. In this work, the surface-modified packing was proposed to be used in the RPB to estimate the regeneration performance, including oxidation and separation efficiency. Three different surface-modified packings of hydrophilic surface-modified wire mesh packing (ISP), non-surface-modified wire mesh packing (NSP), and hydrophobic surface-modified wire mesh packing (OSP) were prepared and employed in the RPB for regeneration experiments. Results show that regeneration performance is in order of ISP＞NSP＞OSP. Compared with OSP, the NaSR conversion, RSSR removal efficiency, and number of transfer units of ISP increased nearly by 34%, 13%, and 21% at 1000 r/min rotational speed and 25 mm packing thickness, respectively. For the view of different packing combination, not only in the inner layer but also in the outer layer, ISP had noticeable superior regeneration performance, which displays the bright future of advanced surface-modified packing used in the RPB for process intensification of reaction and separation.

Defects in the zeolite layer restricts the applications of the zeolite membrane. In this study, we found that the bubbles in the synthesis solution and the interface between the support and the synthesis solution impeded the movement of the Si/Al active ingredients to the surface of the support during the membrane synthesis process, leading to the formation of defects. Accordingly, we pre-degassed the synthesis solution containing 170-mm-long ceramic tube supports under a vacuum of 0.1 MPa at room temperature before the membrane synthesis. The characterization results showed that the degassing pretreatment drove out the gases in the synthesis solution and the interface between the synthesis solution and the support, and thus eliminated pinhole defects in the zeolite layer. The permselectivity of H2 over C3H8 increased from 8.8 to 20.2 when the synthesis solution was degassing pretreated. In conclusion, the degassing pretreatment clearly eliminated the defects in the membrane.

Catalytic decomposition of the hydrogen-rich hydrazine monohydrate (N2H4·H2O) represents a promising hydrogen storage/production technology. A rational design of advanced N2H4·H2O decomposition catalysts requires an overall consideration of intrinsic activity, number, and accessibility of active sites. We herein report the synthesis of a hierarchically nanostructured NiPt/N-doped carbon catalyst using a three-step method that can simultaneously address these issues. The chelation of metal precursors with polydopamine and thermolysis of the resulting complexes under reductive atmosphere resulted in a concurrent formation of N-doped carbon substrate and catalytically active NiPt alloy nanoparticles. Thanks to the usage of a silica nanosphere template and dopamine precursor, the N-doped carbon substrate possesses a hierarchical macroporous-mesoporous architecture. This, together with the uniform dispersion of tiny NiPt nanoparticles on the carbon substrate, offers opportunity for creating abundant and accessible active sites. Benefiting from these favorable attributes, the NiPt/N-doped carbon catalyst enables a complete and rapid hydrogen production from alkaline N2H4·H2O solution with a rate of 1602 h-1 at 50 °C, which outperforms most existing catalysts for N2H4·H2O decomposition.

Development of active and earth-abundant catalysts is pivotal to render hydrazine monohydrate (N(2)H(4)·H(2)O) viable as a hydrogen carrier. Herein, we report the synthesis of noble-metal-free Ni–W–O-derived catalysts using a hydrothermal method in combination with reductive annealing treatment. Interestingly, the thus-prepared Ni-based catalysts exhibit remarkably distinct catalytic properties toward N(2)H(4)·H(2)O decomposition depending upon the annealing temperature. From a systematic phase/microstructure/chemical state characterization and the first-principles calculations, we found that the variation of the apparent catalytic properties of these Ni-based catalysts should stem from the formation of different Ni–W alloys with distinct intrinsic activity, selectivity, and distribution state. The thereby chosen Ni–W alloy nanocomposite catalyst prepared under an optimized condition showed high activity, nearly 100% selectivity, and excellent stability toward N(2)H(4)·H(2)O decomposition for hydrogen production. Furthermore, this noble-metal-free catalyst enables rapid hydrogen production from commercially available N(2)H(4)·H(2)O solution with an intriguingly high hydrogen capacity of 6.28 wt % and a satisfactory dynamic response property. These results are inspiring and momentous for promoting the use of the N(2)H(4)·H(2)O-based H(2) source systems.

A series of dynamic model tests that were performed on a geogrid-reinforced square footing are presented. The dynamic (sinusoidal) loading was applied using a mechanical testing and simulation (MTS) electro-hydraulic servo loading system. In all the tests, the amplitude of loading was ±160 kPa; the frequency of loading was 2 Hz. To better ascertain the effect of reinforcement, an unreinforced square footing was first tested. This was followed by a series of tests, each with a single layer of reinforcement. The reinforcement was placed at depths of 0.3B, 0.6B and 0.9B, where B is the width of footing. The optimal depth of reinforcement was found to be 0.6B. The effect of adopting this value versus the other two depths was quantified. The single layer of geogrid had an effective reinforcement depth of 1.7B below the footing base. The increase of the depth between the topmost geogrid layer and the bottom of the footing (within the range of 0.9B) did not change the failure mode of the foundation.

Significance We report a class of IrRu-N-C catalysts, with Ir and Ru single atoms uniformly populated in nitrogen–carbon composites. The catalyst not only represents an example of high-efficiency single-atom catalysis toward H 2 electrooxidation, but also exhibits excellent CO electrooxidation reaction (COOR) behavior. The traditionally invincible CO electrooxidation process occurs easily on this catalyst, with COOR initiates at nearly 0 mV versus reversible hydrogen electrode at ambient temperature. This endows the catalyst with superb CO antipoisoning property in proton exchange membrane fuel cell at ultralow noble metal loading. Combining theoretical calculation and physical probing techniques, we find that the approximated Ir and Ru single atomic sites act in synergy to confer the catalysts with this excellent CO conversion behavior.

Proteins are like miracle machines, playing important roles in living organisms. They perform vital biofunctions by further combining together and/or with other biomacromolecules to form assemblies or condensates such as membraneless organelles. Therefore, studying the self-assembly of biomacromolecules is of fundamental importance. In addition to their biological activities, protein assemblies also exhibit extra properties that enable them to achieve applications beyond their original functions. Herein, this study showed that in the presence of monosaccharides, ethylene glycols, and amino acids, β-lactoglobulin (β-LG) can form assemblies with specific structures, which were highly reproducible. The mechanism of the assembly process was studied through multi-scale observations and theoretical analysis, and it was found that the assembling all started from the formation of solute-rich liquid droplets via liquid-liquid phase separation (LLPS). These droplets then combined together to form condensates with elaborate structures, and the condensates finally evolved to form assemblies with various morphologies. Such a mechanism of the assembly is valuable for studying the assembly processes that frequently occur in living organisms. Detailed studies concerning the properties and applications of the obtained β-LG assemblies showed that the assemblies exhibited significantly better performances than the protein itself in terms of autofluorescence, antioxidant activity, and metal ion absorption, which indicates broad applications of these assemblies in bioimaging, biodetection, biodiagnosis, health maintenance, and pollution treatment. This study revealed that biomacromolecules, especially proteins, can be assembled via LLPS, and some unexpected application potentials could be found beyond their original biological functions.

A D-shaped optical-fiber refractive index sensor based on surface plasmon resonance is reported. Rigorous coupled-wave analysis was used to simulate the numerical modeling. The influences of differ...

As the field of biomedicine continues to grow, so will the need for the quick and efficient manufacture of high-quality micro-textures, such as microfluidic systems, for biomedical functions. The utilization of a nanosecond-pulsed laser enables the realization of an efficient ablation rate in the preparation of a microscaled texture for biomedicine applications. To obtain high-quality ablated features, it is necessary to understand the interaction regime between the pulse laser and cermet. In this work, the effects of the scanning speed on formation mechanisms of microgrooves in pulse laser scanning ablation of cermet are investigated. The relative ablation processes in terms of the particle ejection and the morphology of the ablation traces under various scanning speeds are characterized. In addition, pump-probe shadowgraph imaging is used to observe the ablation dynamics and laser-plume interaction. The results demonstrate that the plume shielding effect, which stems from the intensive pulse energy overlap in the irradiated region, tends to occur at a low scanning speed and results in an intermittent ablation regime. Moreover, there is a critical scanning speed for overcoming the plume shielding effect when other laser parameters are kept constant. To realize an even and continuous ablation process, a high scanning speed that exceeds this critical value should be applied.