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Pulsed laser annealing (PLA, 527 nm, 200-ns pulse, Nd:YLF laser) was used to activate phosphorous-implanted C-face SiC and repair lattice damage. The electrical and structural characteristics of the implanted material surface were analyzed before and after PLA. Electrical activation was confirmed by the circular transfer length method. The implanted layer was characterized by x-ray diffraction. The change in strain can be attributed to the recovery of lattice damage induced by laser annealing. Transmission electron microscopy (TEM) showed that amorphous 4H-SiC structure was transformed to crystalline structure by PLA. The defect evolution was investigated using TEM images and diffraction patterns.

Here, we compare the porosity, microstructure and mechanical property of 4047 Al–Si alloys prepared by wire-arc additive manufacturing (WAAM) and conventional casting. X-ray microscopy reveals that WAAM causes a higher volume fraction of gas pores in comparison with conventional casting. Effective refinements of α-Al dendrites, eutectic Si particles and Fe-rich intermetallic compounds are achieved by WAAM, resulting from its rapid solidification process. Both ultimate tensile strength (UTS, up to 205.6 MPa) and yield stress (YS, up to 98.0 MPa) are improved by WAAM at the expense of elongation after fracture. The mechanical property anisotropy between scanning direction and build direction is minimal for alloys via WAAM. Additional microstructure refinement and strength enhancement are enabled by increasing the travel speed of welding torch from 300 to 420 mm/min.

Thermite reduction as one of the most promising methods for preparation of TiAl alloy, the metal-slag separation behavior in the whole process of chemical reaction, including both the alloy components and slags to be removed, is still ambiguous. In this paper, the two-step nucleation mechanism was applied to investigate the metal-slag separation behavior in the thermite reduction process for the preparation of TiAl alloy, which was confirmed by thermodynamic calculation based on density functional theory. Moreover, the component of products acquired from thermite reaction was characterized and analyzed by x-ray diffractometer, scanning electron microscope and transmission electron microscope, respectively. According to the results of the experiment and calculation, the formation and separation mechanism between alloy and slag in the process of preparing TiAl alloy via thermite reduction is visualized, which is universal in the whole metallurgical procedure involving redox and slag-making process.

Summary Ionic Coulomb blockade is one of the ion transport phenomena revealing the quantized nature of ionic charges, which is of crucial importance to our understanding of the sub-continuum transport in nanofluidics and the mechanism of biological ion channels. Here, we report an experimental observation and plausible theoretical reasoning of ionic conduction oscillations. Our experiment is performed under confinement in sub-nanometer (sub-nm) MoS2 pores with optoelectronic control enabled for active tuning of pore surface charges. Under this charge control, we measure the ionic current at fixed voltages and observe multiple current peaks. Our analytical discussions and molecular dynamics simulations further reveal that the conductance oscillations may originate from the multi-ion interaction at the pore entry, particularly the electrostatic repulsion of ions external to the pore by ions bound inside the pore. Our work adds a further understanding of ionic Coulomb blockade effect and paves the way for developing advanced ionic machineries.

In this work, a method was investigated to extract trench sidewall and trench bottom capacitances of a SiC trench metal–oxide–semiconductor (MOS) structure. Five groups of 4H-SiC trench MOS capacitors were designed and fabricated, with various trench bottom widths and trench mesa widths. High-frequency capacitance–voltage (HFCV) measurements at 100 kHz were performed on these trench MOS structures. The relationships between trench MOS capacitances and the widths of trench bottom as well as trench mesa were studied. As expected, under the same bias voltage, the measured trench MOS capacitances were proportional to the trench bottom widths and trench mesa widths. Based on this, the contributions of capacitances from the bottom, mesa, and sidewall of trench in trench MOS structure were studied systematically. The oxide thicknesses at different locations in trench were extracted. The ${C}$ – ${V}$ characteristics of the MOS capacitors from trench sidewall and trench bottom could also be deduced, from which the flat-band voltage and the charges in oxide of these two MOS capacitors could be subsequently calculated and analyzed. This method provides a convenient and precise technology to monitor process control in SiC trench MOSFETs manufacturing.

This paper describes a small-strain poroelasticity model to examine the interstitial fluid pressure and matrix deformation in a non-homogeneous solid tumor consisting of an inner core with a reduced specific microvascular area encapsulated in an outer tissue shell with a regular specific microvascular area. A singular perturbation technique is employed to capture the transitional behavior at the interface between the inner core and outer shell under a cyclic microvascular pressure. The perturbation solution reveals the existence of two boundary layers: one at the interface between the inner core and outer shell, and the other at the tumor surface. The amplitude of the tumor interstitial fluid (TIF) pressure is at a lower constant level in the inner core and increases rapidly in the boundary layer at the interface between the inner core and outer shell to the pressure value of the corresponding homogeneous tumor with the outer shell properties. The radial strain undergoes dramatic changes in the boundary layers, and reaches the peak near the interface between the inner core and outer shell. The behavior of the effective stresses remains similar to that of the TIF pressure.

Herein, the mid-infrared (7.7–13.7 μm) diamond-based phase shifter was designed and optimized by finite-element analysis. The ridge-shaped diamond waveguide is designed and doped to form the intern...

In this article, an ultrawideband magnetic probe with high electric field suppression ratio (EFSR) is proposed. The probe has three parts: the loop part, the transmission part, and the head part. Shield metal sheets are designed in the loop part to enhance EFSR. The tapered transmission line in the transmission part and the quasi coaxial transition in the head part are adopted for impedance matching between the induction loop and the grounded coplanar waveguide (GCPW) in the head part. Then, segmented resistance–inductance–capacitance ( RLC ) equivalent circuit models of the probe are proposed for magnetic field coupling and electric field coupling, which are suitable for accurate modeling and efficient optimization of the magnetic probe. In addition, the coupling capacitors between the shield metal sheets and the device under test (DUT) are extracted utilizing the conformal transforming method with analytical formulas. Finally, this magnetic probe is fabricated under printed circuit board (PCB) technology and used in measuring the magnetic field distribution. The measurement and simulation results agree well. The probe has a bandwidth of 100 MHz–30 GHz and an EFSR of higher than 21 dB. Compared with the conventional probe with similar bandwidth, the proposed probe can improve the EFSR by 9 dB.

Cholesteric liquid crystals with selective reflection have important applications in the field of light control and optical thin films. In this study, a series of side-chain cholesteric liquid-crys...

To solve the technical problems of hot metal desulfurization by injecting magnesium particulate, a new method of hot metal desulfurization by bottom-blowing magnesium vapor combined with mechanical agitation was put forward. The effects of three different desulfurization processes on the desulfurization efficiency were studied in view of thermodynamics and kinetics. It was found that the utilization efficiency of magnesium can reach 82.6% and desulfurization efficiency can reach 86.2% during the first 4 min using the method of magnesium vapor injection combined with mechanical agitation. The gasification of magnesium powder leads to significant splashing and magnesium losses in the process of magnesium powder injection, resulting in a low utilization efficiency of magnesium of 51.8% and a low desulfurization efficiency of 55.76%. Activation energy for a first-order kinetic relationship between magnesium powder and sulfur was measured from the experiments, which was 142.82 kJ/mol in the temperature range of 1573–1723 K. The activation energy of the reaction between magnesium vapor and sulfur was around 54.8–65.0 kJ/mol in the temperature range of 1573–1723 K, which indicates that the desulfurization with magnesium vapor proceeds relatively easier than the desulfurization with magnesium powder.

The condensation behavior of magnesium vapor in argon was studied. Thermodynamic analysis showed that magnesium vapor condensation was controlled by partial pressure and temperature and that temperature was the main factor affecting condensation. When the actual magnesium vapor partial pressure was 371.2 Pa, the magnesium vapor changed from gas to liquid and then to solid. Experimental results showed that droplet magnesium with particle sizes of 0.15 to 1.04 mm, transitional condensed magnesium with particle sizes of 2 to 25 μm and powdered magnesium with particle sizes of 0.5 to 8 μm were obtained at 1000 °C and 0.2 m3/h. This phenomenon occurred as the temperature in the constant temperature zone increased from 1000 °C to 1200 °C. The initial temperature of the droplet condensation zone increased from 618 °C to 776 °C; the initial temperature of transitional condensation zone was 492 °C to 552 °C and the initial temperature of the powder condensation zone 420 °C to 458 °C. When the argon flow rate increased from 0.1 to 0.4 m3/h, droplet magnesium decreased from 52.68 to 11.32 pct and the powder magnesium increased from 24.06 to 57.98 pct. Controlling the temperature and gas flow, different magnesium crystalline microstructures were obtained, which provided a means for magnesium vapor condensation in a continuous magnesium extraction process.

High ferrotitanium is used as a deoxidizer and alloying agent in steelmaking processes and is mainly produced using high-cost remelting processes. The thermite method is a simple and low-cost method for preparing low ferrotitanium. However, the high levels of S, Al, and O residues in the product severely restrict its applicability in the low-cost preparation of good-quality high ferrotitanium. In this study, a novel multistage deep reduction method for preparing high-quality high ferrotitanium is proposed, and the multistage desulfurization mechanism is systematically investigated. The results indicate that multistage desulfurization is an effective method for reducing the S content of high ferrotitanium prepared via the thermite method. During the strong desulfurization stage, Ti2S reacts with CaO at the slag–metal interface and produces CaS. The S content decreases, while the O content increases, with the increase of CaO in the CaO–Al2O3-based slag. During the deep desulfurization, Ti2S is deeply reduced by the Ca and produces CaS, thus further reducing the S content. The S content decreases with the incremental addition of Ca and can be reduced to 0.035 wt% after multistage desulfurization.

The ability to engineer microscale and nanoscale morphology upon metal nanowires (NWs) has been essential to achieve new electronic and photonic functions. Here, this study reports an optically programmable Plateau-Rayleigh instability (PRI) to demonstrate a facile, scalable, and high-resolution morphology engineering of silver NWs (AgNWs) at temperatures150 °C within 10 min. This has been accomplished by conjugating a photosensitive diphenyliodonium nitrate with AgNWs to modulate surface-atom diffusion. The conjugation is UV-decomposable and able to form a cladding of molten salt-like compounds, so that the PRI of the AgNWs can be optically programmed and triggered at a much lower temperature than the melting point of AgNWs. This PRI self-assembly technique can yield both various novel nanostructures from single NW and large-area microelectrodes from the NW network on various substrates, such as a nanoscale dot-dash chain and the microelectrode down to 5 μm in line width that is the highest resolution ever fabricated for the AgNW-based electrode. Finally, the patterned AgNWs as flexible transparent electrodes were demonstrated for a wearable CdS NW photodetector. This study provides a new paradigm for engineering metal micro-/nanostructures, which holds great potential in fabrication of various sophisticated devices.

The novel method for the preparation of titanium powder by multi-stage reduction was proposed. The primary reduction adopted self-propagating high-temperature synthesis (SHS) mode. This paper focuses on the primary reduction process of Mg–TiO2 system under the condition of off-balance reaction. The effects of different material ratios, material arrangement methods and reaction initiation modes on the SHS reaction process of Mg–TiO2 system and its reaction mechanism were systematically studied. SHS mode was used to Mg–TiO2 system, and non-stoichiometric low-valent titanium oxide intermediate including α-Ti (Ti2O type) and TiO was directly obtained (with oxygen content of 13.93 wt%). SHS reaction initiated by local ignition is more sufficient than by overall heating method. Compared with the loose setting materials, the compacts can increase the effective contact interface of the reactants, and SHS reaction proceeds more sufficiently, which is favorable for obtaining lower oxygen content product. The adiabatic temperatures of the Mg–TiO2 system at different initial conditions were calculated according to the improved calculation method. When the initial temperature is 298 K, the adiabatic temperature of Mg–TiO2 system is between 1363 and 2067 K at different material ratios. Therefore, unreacted or partially excess Mg at the reaction front will diffuse into the unreacted region in gas or liquid form, thereby preheating the material and initiating further SHS reaction.

Titanium ores are plentiful in the earth crust, and the corresponding metal content ranks as the fourth among structural metals; the application of titanium metal is restricted for its high cost in...

It is well known that transport of nutrients and wastes as solute in bone fluid plays an important role in bone remodeling and damage healing. This work presents a chemo-poroelastic model for fluid and solute transport in the lacunar-canalicular network of an osteonal cortical bone under cyclic axial mechanical loading or vascular pressure. Analytical solutions are obtained for the pore fluid pressure, and fluid and solute velocities. Numerical results for fluid and calcium transport indicate that under a cyclic stress of 20 MPa, the magnitudes of the fluid and calcium velocities increase with an increase in the loading frequency for the frequency range considered (≤ 3 Hz) and peak at the inner boundary. The peak magnitude of calcium velocity reaches 18.9 μm/s for an osteon with a permeability of 1.5 × 10−19 m2 under a 3 Hz loading frequency. The magnitude of calcium velocity under a vascular pressure of 50 mmHg is found to be two orders of magnitude smaller than that under the mechanical load. These results have the potential to be important in understanding fundamental aspects of cortical bone remodeling as transport characteristics of calcium and other nutrients at the osteon scale influence bone metabolism.

In this paper, a new type of copper (Cu) matrix graphite composite was successfully prepared, which was reinforced with titanium nitride particles (TNPs) using powder metallurgy. These composites contained 2 wt % graphite as the lubricating phase and 1, 3, 5, 10, and 15 wt % TNPs as the reinforcing phase. The effects of different TNP contents on composite properties and the composites' wear mechanism were examined. The samples were characterized by microstructure, density, porosity, hardness, compressive yield strength, and friction wear testing. The results showed that, with TNP addition, the hardness, compressive strength, and friction and wear properties of the composites were improved. When the TNP content was >3 wt %, composite porosity gradually increased and the hardness, compressive strength, and friction and wear properties of the composites sharply decreased. With TNP addition, the main composite wear modes gradually changed from adhesive and abrasive wear to abrasive wear.

Metal magnesium is mainly produced from the calcined dolomite by the vacuum silicothermic process. However, it requires a high energy input. An improved process was proposed in which the magnesium was produced from pre-prepared pellets. In this work, diffusion and phase transformations in the pre-prepared pellets during the reduction process were investigated. The results suggested that the reduction ratio is remarkably increased as the reduction temperature increased or the dolomite/ferrosilicon molar ratio decreased. Only Si diffused into dolime, which caused the reduction reactions and Fe might not have been involved in the reactions. The liquid Ca-Si alloy was produced. CaSi was an important intermediate product to produce CaSi2 and Ca vapor. Both CaSi2 and Ca vapor were the effective reducing agents for MgO. This process for Mg production includes both solid–liquid and solid–gas reactions. A plausible reactions route was proposed based on experimental and thermodynamic analyses.

In this study, a series of cholesteric liquid crystal elastomers (ZSD series) was synthesised by hydrosilylation reaction among monomer ML1 containing cholesteryl group, monomer ML2 as the crosslin...

Paper-based electronics are gaining increasing attention because of their merits of low cost, degradability, and foldability. However, the roughness and porosity of paper are not conducive to the d...

Mechanochemical reaction involves simultaneous chemical reaction and particle crushing; the latter increases the effective reaction area and improves the reactivity, thus enhancing its kinetics. The classical shrinking core model was used to model the kinetics of bastnaesite mechanochemical decomposition in NaOH solution, which shows a questionable result. Mechanochemical reaction is a dynamic process, where the particle shape and concentration in reaction interface undergo constant change. Thus, a physically consistent model was applied to describe the kinetics. The variations in OH− concentration and particle shape were considered in the revision of model. Considering the variation in OH− concentration in solution with time, the model with varying OH− concentration agrees better with the experimental data, improving the regression coefficients to between 0.936 and 0.992. By introducing fractal geometry to deal with the irregular system, the model was further optimized, and the regression coefficients increase to between 0.940 and 0.997. All these models considere shrinking particle approaches and controlling mechanisms for the diffusion and chemical reaction. Finally, the fractal model with varying OH− concentration was selected to describe the mechanochemical decomposition of bastnaesite, which indicates that the process is controlled by chemical reaction.

CeO2 was successfully prepared by electrotransformation of CeCl3 solution in previous work. In this work, the oxidation mechanism of Ce3+ was determined by cyclic voltammetry and a potential-pH diagram, which indicated that Ce3+ was oxidized by oxygen during the electrotransformation, and the important role of the oxygen content in solution was confirmed. Thus, the influence of atmosphere (air/argon/oxygen) on CeO2 preparation was investigated by adjusting the gas type and flow rate. XRD patterns demonstrated the cubic fluorite structure and grain size of CeO2. With an increase in the gas flow rate, the grain size decreased, but the particle size increased. This result indicated that the smaller grains contained more lattice defects and higher surface energy, so the grains preferred to agglomerate together, forming larger particles. XPS spectra proved that Ce3+ and Ce4+ both existed in the CeO2 samples. Raman scattering revealed that more oxygen vacancies could be produced with an argon atmosphere and high gas flow.

1-Ethyl-2, 3-dimethylimidazolium nitrate [C2mmim][NO3] is a typical solvent for industrial applications. Under inappropriate temperatures, [C2mmim][NO3] may present a flammability hazard due to thermal decomposition. This study investigated the thermal stability and flammability of [C2mmim][NO3] via simultaneous thermogravimetric analyzer, homemade combustion test device (CTD) with high speed camera, and thermogravimetry coupled with Fourier transform infrared spectroscopy (TG-FTIR). The thermal decomposition of [C2mmim][NO3] was divided into two parts based upon the dynamic experiments, and the maximum operating temperature was determined to comprehensively estimate the thermal stability of [C2mmim][NO3]. CTD experiments indicated that [C2mmim][NO3] could produce intense combustion when heated. Further TG-FTIR experiments confirmed that [C2mmim][NO3] decomposed to produce a large number of flammable gases, such as ethylene, which might be the reason that [C2mmim][NO3] has prominent flammability.

Single-molecule techniques such as electron tunneling and atomic force microscopy have attracted growing interests in protein sequencing. For these methods, it is critical to refine and stabilize the protein sample to a “suitable mode” before applying a high-fidelity measurement. Here, we show that a planar heterostructure comprising boronic graphene (BC3) and nitrogenized graphene (C3N) sandwiched stripe (BC3/C3N/BC3) is capable of the effective stretching and confinement of three types of intrinsically disordered proteins (IDPs), including amyloid-β (1–42), polyglutamine (Q42), and α-Synuclein (61–95). Our molecular dynamics simulations demonstrate that the protein molecules interact more strongly with the C3N stripe than the BC3 one, which leads to their capture, elongation, and confinement along the center C3N stripe of the heterostructure. The conformational fluctuations of IDPs are substantially reduced after being stretched. This design may serve as a platform for single-molecule protein analysis with reduced thermal noise.

To solve the technical problems of hot metal desulfurization by injecting magnesium particulate, a new idea of hot metal desulfurization by bottom-blowing magnesium vapor was put forward. The reaction mechanism of hot metal desulfurization with magnesium vapor injection was analyzed, and the kinetic model of the desulfurization rate during the process of hot metal desulfurization with magnesium vapor injection was established. The dimensionless equation of the gas–liquid mass transfer coefficient under the injection conditions was obtained by the dimensional analysis method. And the theoretical calculation results were in good agreement with the experimental measurements. The results show that the diameter of the bubbles and the viscosity of the melt significantly affect the desulfurization rate of hot metal injected with magnesium vapor. When the temperature is 1573 K and the gas flow rate is 3 L/min, the desulfurization rate can reach 79% and the utilization rate of magnesium can reach 83%.

In order to increase the contact area and promote the mass transfer process of gas and liquid, the process of the bubble refinement in a metallurgical reactor with mechanical agitation was studied by physical simulation. Based on the capillary number, a prediction equation for the bubble refinement was established. The effects of the gas flow rate, the stirring speed and the stirring depth on the bubble refinement in the reactor were discussed in detail. The distribution of the bubble diameter in the reactor was obtained under different conditions. The results show that when the stirring speed reaches 300 r/min, the bubble diameter mainly distributes in the range of 1–2 mm. A higher gas flow rate may increase the number of bubbles in the melt and promote the bubble refinement process. The mechanism of bubble refinement under mechanical agitation was analyzed, and the results indicated that the stirring speed, the blade area and the blade inclination are the main influencing factors.

The Pidgeon process is the main extraction method of magnesium, but its continuous production cannot be achieved due to the switch between vacuum and atmospheric pressure. Therefore, it is vital to realize continuous extraction of magnesium under atmospheric pressure. In this paper, the process of extracting magnesium from prefabricated pellets in flowing argon was proposed. The isothermal kinetic analysis of the reduction process was carried out. The results showed that the reduction process was controlled by diffusion process in 1 h, and the apparent activation energy of extracting magnesium from prefabricated pellets in flowing argon was 218.75 kJ/mol. Then the influence of experimental factors on the reduction rate was explored, including briquetting pressure, carrier gas flow rate, ferrosilicon content, reaction temperature and time. Through analysis and calculation, it was concluded that the main control step of diffusion process was silicon diffusion.

The effect of ZnO/PbO and FeOX/SiO2 on the viscosity of the PbO-ZnO-Fe3O4-SiO2-CaO slag was measured using the rotating spindle method. The slag viscosity decreased with decreasing ZnO/PbO mass ratio because of the depolymerization of the silicate structures. The viscosity decreased with increasing FeOX/SiO2 mass ratio as the experimental temperature was above 1623 K, while the viscosity increased significantly with the increase of FeOX/SiO2 as the experimental temperature below 1623 K because of the phase transition and the change of slag melting point. According to XRD analysis of as-quenched slag, the spinel and the zincite phase increased with increasing FeOX/SiO2. Increasing ZnO/PbO and FeOX/SiO2 could enhance the crystallization capacity of the slag. FTIR analysis revealed that the degree of polymerization of the as-quenched slags decreased with decreasing ZnO/PbO and increasing FeOX/SiO2. The temperature dependencies of the viscosity on ZnO/PbO and FeOX/SiO2 were investigated, and the apparent activation energies of each system were found to be between 169.5 to 227.4 KJ/mol, and 151.1 to 676.4 KJ/mol, respectively.

Rational construction of Z-scheme photocatalysts and exploration of the Z-scheme charge transfer mechanism have drawn much attention in the field of CO2 reduction because of its great potential to alleviate energy crisis and environmental problems. In this study, a series of Z-scheme CdS/BiOI composites were constructed by depositing CdS nanoparticles on the surface of BiOI nanosheets. The synthesized materials were characterized comprehensively, and their photoreduction CO2 activities were evaluated. The results show that the composites exhibit higher photoreduction CO2 activity under visible light irradiation (λ > 400 nm) than pure CdS and BiOI. The yields of CO and CH4 for the optimal composite after 3 h irradiation are 3.32 and 0.54 μmol/g, respectively. The improved photocatalytic activity is attributed to Z-scheme transfer mode of the photogenerated charges in the composites. The mechanism of CO2 reduction is proposed and verified experimentally.

Ultrafine rare-earth oxides (REOs) are widely applied in all fields of daily life, but the conventional preparation methods are limited by a long procedure, low efficiency and severe environmental pollution. Our team has independently developed a jet pyrolysis reactor for the preparation of ultrafine cerium oxides, and this process has theoretical significance and practical application values. In this study, gas–solid pyrolysis reactions inside the jet-flow pyrolysis reactor were numerically simulated. We performed a coupling computation of the combustion, phase transformation and gas–solid reaction on Fluent and user-defined functions. We characterized the flows of different phases as well as the compositions and distributive laws of the reactants/products in the reactor. The gas-phase inlet velocity and dynamic pressure/additional pressure were related by a quadratic function. The velocity at the throat inlet changed the most, and the outlet velocity was very stable. The CeO2 concentrations were obviously stratified. This study enriches theories of jet-flow pyrolysis and theoretically underlies the optimization and popularization of self-developed pyrolysis reactors.

The figure of merit parameter (Z) for an anisotropic thermoelectric (TE) material is dependent on direction, and the highest Z has been used to characterize the energy conversion efficiency of anisotropic TE materials. It is, however, not clear whether the material properties in other directions also play a role in the TE generator efficiency. This work presents a three-dimensional (3D) model to investigate the direction dependence of energy efficiency for orthotropic TE materials. It is analytically proved that the peak efficiency is a function of Z in the leg direction, the thermal conductivity (separate from that in Z) in the leg direction and the thermal conductivities in the lateral directions, but is independent of lateral electrical conductivities. Numerical examples indicate that the energy efficiency is insensitive to the lateral thermal conductivities, but increases with an increase in the thermal conductivity in the leg direction for a fixed Z in the leg direction. Moreover, the efficiency of an orthotropic material with the leg in a lower Z direction may become higher than that with the leg along the highest Z direction, depending on the thermal conductivity in the leg direction, which indicates that orienting the highest Z direction along the leg may not necessarily achieve the highest TE generator efficiency. The effects of anisotropy on the efficiency are coupled with heat loss along the lateral surface and become less significant for small surface heat transfer coefficients.

In this study, we synthesised two series of cholesteric liquid crystal polymers CPQ and CPZ series. First, we prepared four different monomers ML1 containing a cholesteryl group, ML2 containing a c...

We synthesized two series of cholesteric liquid-crystal elastomers by hydrosilylation among monomers MA containing a cholesteryl group, MB (MC) containing a phenolic hydroxyl group and MD a...

4-Amino-1,2,4-triazole picrate (4-ATPA) is a type of ionic liquids, as well as an explosive with sound thermal stability and low mechanical sensitivity. However, under upset conditions such as high temperature and pressure, an unpredictable explosion would occur and result in huge casualties and property losses. The purpose of this research was to evaluate the thermal hazard and runaway reaction of 4-ATPA through high-pressure differential scanning calorimetry and accelerating rate calorimeter. The kinetic parameters of decomposition reaction under non-isothermal and different pressure conditions were calculated based on the experiment results. Experimental results showed that the β and test pressure had no effect on the amount of heat release. Adiabatic experiments indicated that 4-ATPA had a high onset temperature at 196.8 °C. The maximum self-heating rate (3567.9 °C min−1) and pressure rise rate (202.0 bar min−1) revealed the vulnerability of 4-ATPA to suffer a disastrous explosion. Moreover, the apparent activation energy and pre-exponential factor were evaluated as 110.2 kJ mol−1 and 1.8 × 10−15 s−1 by ASTM E698 method. The correctness of the thermodynamic calculation formula under adiabatic conditions is verified by ARC tests. Finally, the thermal hazard risk of 4-ATPA was classified as unacceptable based on the risk classification criteria.

Rational construction of Z-scheme photocatalysts and deep exploration of Z-scheme transfer mechanism are highly desirable for improving the activity of CO2 reduction photocatalysts but remains a significant challenge. Herein, we synthesized a series of heterostructured CdS/CdWO4 materials by selectively depositing CdS nanoparticles on the edges of CdWO4 nanoplates. Selective deposition mechanism of CdS and the formation of the composites were studied in detail. The photocatalytic CO2 reduction activities of the synthesized materials were investigated and the results show that CdS/CdWO4 materials exhibit higher photocatalytic activity than pure CdS and CdWO4. We suggest that the enhanced photoreduction CO2 activity is attributed to Z-scheme charge transfer mechanism based on the analyses of the products of CO2 reduction and the band structure of CdS and CdWO4. Kelvin probe force microscope on CdWO4 nanoplates shows that the photogenerated electrons, driven by electric field forces, would migrate to the edge of CdWO4. The charge transfer direction, coupling with the selective deposition of CdS nanoparticles, facilitates CdS/CdWO4 composites following Z-scheme transfer. In-situ Pt photodeposition tests provide strong experimental support to the charge transfer mechanism. The results gained herein are expected to provide some useful insights into the structure-oriented rational design of Z-scheme photocatalysts for CO2 reduction.

Few-layer graphene (FLG) exfoliated from graphite is an attractive electrode material due to its high conductivity and high chemical stability. But usually limited by their specific surface area (SSA), its capacitance needs to be improved when used in supercapacitors. In this study, FLG has been prepared by combining electrochemical exfoliation and thermal expansion. It has a SSA of 148 m2/g and delivers a capacitance of 55 F/g at a discharge current density of 1 A/g. To increase its capacitance, carbon nanotubes (CNTs) and MnO2 nanoparticles are functionalized onto FLG surface separately. Both modification could achieve a composite electrode with enhanced capacitance. The CNT/FLG and MnO2/FLG electrodes show a specific capacitance of 106 and 336 F/g at the current density of 1 A/g, respectively, while the former exhibits a much better rate performance and cycling stability than the latter. This work demonstrates an optional way to improve the performance of FLG-based supercapacitors.

Ferrotitanium is used as a deoxidizer, a degassing agent and an alloying element additive in the steel industry. The thermite method, as a way of preparing ferrotitanium, has the advantages of abundant raw material resources, low energy consumption, and low production costs. However, Al and O impurities in ferrotitanium prepared by this method change greatly with its Ti content. The distribution of Al and O residuals and their relationship with the Ti content of the ferrotitanium prepared by the thermite method were studied. The results show that Al and O residuals in the ferrotitanium prepared by the thermite method are mainly caused by intermetallic compounds and Al2O3 inclusion. The Al and O residuals are the quadric function of the Ti content in the alloy prepared by thermite reduction. With increasing Ti content in the ferrotitanium, the amount of intermetallic compounds and Al2O3 inclusions both increase. When the Ti content in the alloy is lower than about 30%, the Al residual in the ferrotitanium prepared by the thermite method is mainly caused by Fe-Al intermetallic compounds, while the O residual is mainly caused by the Al2O3 inclusion. When the Ti content in the alloy is higher than about 30%, the Al residual in the ferrotitanium prepared by the thermite method is caused by Ti-Al intermetallic compounds and Al2O3 inclusion, while the O residual is mainly caused by a great number of Al2O3 inclusions and sub-oxides, such as Ti4Fe2O.

A novel continuous and controllable combustion synthesis process for fabrication of TiAl alloy from TiO2, Al, KClO3 and CaO was developed in this paper. The effects of different material ratios on the composition of alloy and the separation effect of alloy and slag were studied. Based on the mass action concentration model, the phase equilibrium composition of Ti-O-Al system at 1800 K was also investigated. The as-cast TiAl alloys were analyzed by X-ray diffractometer, scanning electron microscope, inductively coupled plasma emission spectrometer and Oxygen/Nitrogen/Hydrogen analyzer. According to the comparison between theoretical calculation and experimental results, the variation trends for the alloy composition from experiment are well consistent with calculation results along the increase of Al addition amounts in raw materials. The analyzed composition of alloy for Ti, Al and O are 56.53, 40.99 and 1.09 (wt. %), respectively. This present method hopefully supplied an efficient way for preparation of Ti- or Al-based alloys.

For the development of ceramic candidates for thermal barrier coatings, two kinds of new ceramics, Y3Ce7Ta2O23.5 and Yb3Ce7Ta2O23.5, were synthesized by sintering at 1873 K for 10 h. The obtained samples were composed of a single fluorite-type phase, and their relative densities are greater than 90%. Because of phonon scattering caused by the complex lattice, the large number of oxygen vacancies, and substituted atoms, the thermal conductivity is lower than that of 8YSZ. The coefficients of thermal expansion (CTEs) of these two products are located in the range of 10.22–12.57 × 10−6/K and 9.62–12.66 × 10−6/K, respectively, from 323 K to 1473 K, and they also exhibit excellent phase stability up to 1473 K. However, their thermal conductivities and CTEs are lower than those of RE2Ce2O7 (RE = La, Nd, or Sm).

In this paper, we analyze the piezo-thermoelectric responses of an integrated n-type piezoelectric semiconducting (PS) thermoelectric (TE) film and substrate membrane structure. Equations governing the behavior of the laminated PSTE structure are first derived based on the phenomenological theories of thermoelectricity and piezoelectric semiconductors. Closed form solutions of stress, deformation, electric displacement and electric field are obtained under a steady state thermal gradient and fixed grip end conditions. A parametric study for a zinc oxide (ZnO) PSTE film sandwiched between zirconia (ZrO2) substrate membranes show that both tensile and compressive stresses develop in the ZnO film and all field variables are dramatically influenced by the pyroelectric constant.

In the paper, mechanochemical decomposition (a combine of mechanical milling and chemical decomposition) on bastnaesite concentrate with NaOH solution was studied. Particle size, BET specific surface area and pore volume were measured to study the structural developments of decomposition residue containing activated bastnaesite and decomposition product RE(OH)3. X-ray diffraction analysis and SEM-EDS were used to investigate the microstructural changes. The results showed that at the early stage, breakage from balls to particles played an important role. The particle size in initial bastnaesite decreased rapidly from 125 μm to 7.25 μm and specific surface area increased remarkably from 0.04 m2/g to 7.33 m2/g in the first 5 min. The bastnaesite particles with fresh surface could directly react with NaOH, and increase in amorphization degree obviously improved reactivity of bastnaesite. At the later stage, with progressive decomposition, the thickness of product layer increased and the structure became dense with decrease in the pore volume from 0.031 cm3/g to 0.024 cm3/g. In addition, this is accompanied with increase in the crystallinity degree and crystallite size as well as decrease in the microstrain. Thus, the decomposition of bastnaesite can be enhanced. Washing efficiency of fluorine reached 97.6% at 180 °C using 56% of NaOH concentrate with 0.8:1 of liquid-solid for 180 min. Finally, the change of fluorine washing efficiency with time further verified the result that the reaction controlling step had a transformation from chemical reaction to diffusion control through product layer.

In terms of secondary resource recovery and environmental impact, fly ash is attracting a great deal of attention in China. This study aimed to investigate the carbochlorination process of titanium oxide to recover titanium. The extraction kinetics mechanism of titanium oxide from fly ash was investigated at temperatures ranging from 850°C to 1050°C. The effect of various experimental parameters was studied. The reactants and reaction residues were analyzed by scanning electronic microscopy and chemical analysis. The results show that the best extraction efficiency of 91.66% was obtained at a temperature of 1050°C, a coking coal content of 34.64 wt.%, a pellet diameter of 8 mm, an average gas flow of 0.35 L/min, and a time of 120 min. The carbochlorination reaction of titanium oxide is controlled by the chemical reaction. The apparent activation energy is approximately 44.45 kJ/mol between 800°C and 1050°C.

Graphite particles and boron carbide (B4C) particles were added into copper matrix composites by powder metallurgy to form a new composite-reinforced and lubricated system. The effects of different amounts of B4C particles on the properties of composites were studied. With addition of 2 wt % graphite powder as the solid lubricating phase, the effects of B4C particle content on the microstructure, density, porosity, Vickers hardness, compressive strength, and the friction and wear properties of the copper-matrix/graphite self-lubricating composite materials were investigated. The results indicate that increasing addition of B4C particles significantly improved the density, Vickers hardness, compression strength; friction and wear properties of composites. However, excess B4C particles also increased porosity. The connected netted B4C particles disrupt the continuity of the metal matrix causing serious decreases in density, Vickers hardness, compression, and the friction and wear properties of the composite material. Of the tested composites, the materials containing 1.5 wt % B4C showed the best friction and wear resistance properties.

Difficult-to-machine material parts with curved surface are widely used in automobile, aviation, and aerospace fields, and the high-speed milling is the preferred processing method. In high-speed milling process of the curved surface parts, the instantaneous cutting amount is continuously changing due to the geometric feature change of the determined curve toolpath. In this way, the actual processing parameters, including cutting depth, cutting speed, and feed per tooth, are also continuously changing along the curve toolpath, which will result in a severe variation of cutting heat that has negative impact on the tool wear and the surface integrity. For TC4 which is a kind of typical difficult-to-machine material, a novel analysis method of cutting heat is proposed by transforming from time-varying variable to constant parameter for the dry milling of TC4 curved surface. As the actual processing parameters have strong correlational relationship with the instantaneous processing parameters, including instantaneous cutting area, maximum effective cutting radius, and maximum undeformed cutting thickness, the correlational relationship between the actual processing parameters and instantaneous processing parameters is established firstly. By means of fine-tuning the allowance for finish machining and regenerating the curve toolpath, the instantaneous processing parameters can be adjusted to be constant, and the transforming from time-varying variable (actual processing parameters, including cutting depth, actual cutting speed, and feed per tooth) to constant parameter (instantaneous processing parameters, including instantaneous cutting area, maximum effective cutting radius, and maximum undeformed cutting thickness) is realized. Finally, a series of milling experiments are carried out based on the regenerated curve toolpath. The results show that the cutting temperature fluctuation in curved surface milling along the regenerated curve toolpath is decreased by at least 75.81% compared with that in traditional curved surface machining, which is closer to the variation tendency of cutting temperature in plane milling. Consequently, the cutting temperature variation can be smoother by maintaining the instantaneous processing parameters constant, which is of great significance to restrain tool wear and improve surface integrity. Furthermore, the achievement provides theoretical guidance for the allowance distribution of finish machining in the dry milling of TC4 curved surface.

In this study, we designed, synthesised and characterised two series of cholesteric liquid crystal polymers, QP series and ZP series. With polymethylhydrosiloxane as the main chain, QP series were ...

The present work aims to investigate the effect of interfacial thermal resistance on thermal fracture behavior of bonded and composite materials. We consider a sub-interface crack parallel to the i...

High ferrotitanium prepared directly by the thermite method has a disadvantageously high O content (≥ 10 wt%) because of the short slag-metal separation time. In this study, CaO and CaF2 are added to the melt to improve the basicity of the slag and melt separation under heat preservation is performed to strengthen slag-metal separation. The thermodynamics of the step-by-step reduction process of TiO2 in the Ti–Al–Fe–Si–O system whose composition is close to the alloy after melt separation were calculated. Samples of alloys and slags before and after melt separation were systematically analyzed. The result indicates that the reaction that TiO is reduced by Al to Ti is the limited step in the reduction process of TiO2. The O content of the alloys slightly decreases with temperature from 1873 to 2023 K, which agrees with the changes in the law of deoxidation limit. It is mainly attributed to the movement of chemical reactions in the alloy melt at different temperatures and slag-metal interfacial reaction. The addition of Al2O3–CaO–CaF2 slag and high temperature promote the removal of Al2O3 and titanium suboxides. The minimum contents of O and Al in the alloy reach 1.84 wt% and 3.26 wt%, respectively.

Regular nanofluidic sieving structures are emerging as rapid and compatible on-chip techniques for biomolecular separation. Although the current nanofluidic sieving devices, mostly based on three-dimensional nanostructures, have achieved a separation resolution of ∼20 nm, it is still far away from single-nucleotide resolution. Using all-atom molecular dynamics simulations, here we demonstrate a two-dimensional (2D) nanofluidic sieve consisting of an in-plane graphene (GRA)/hexagonal boron nitride (h-BN) nanoarray, which enables ultrahigh resolution in the successful separation of four types of single nucleotides. The alternating GRA and h-BN stripes can create size-dependent energy barriers for adsorbed nucleotides, which provide a strong modulation for their mobility, thus causing distinct band separations on the 2D surface. We further show that this 2D sieve is particularly sensitive when the sample dimensions are within the range from a half period to one period of the nanoarray. This 2D sieving structure may shed light on the development of lab-on-a-chip sequencing in the future.

This paper presents an investigation on the interstitial fluid pressure and stress reductions in a vascularized solid tumor using a thermal therapy approach. The solid tumor is modeled as a fluid infiltrated poroelastic medium with a pressure source subjected to spatial heating. The distributions of temperature, interstitial fluid pressure, strains and stresses in a spherical tumor are obtained using a thermoporoelasticity theory in which the extracellular solid matrix and the interstitial fluid have different coefficient of thermal expansion (CTE). The numerical results for a solid tumor subjected to uniform spatial heating indicate that the CTE of the solid matrix of the tumor plays a crucial role in the reductions in the fluid pressure and effective stresses caused by the thermal therapy. The pore pressure and effective stresses are reduced when the CTE of the solid matrix is higher than that of the interstitial fluid. The reductions in fluid pressure and stresses may become significant depending on the difference between the CTEs of the solid matrix and interstitial fluid. The reductions reach the maximum at the tumor center and decrease with increasing radial distance from the tumor center. Finally, the thermally induced fluid flow is directed from the surface towards the center thereby potentially improving the microcirculation in the solid tumor.