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The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetration process. In this paper, experiments of WFeNiMo HEA and tungsten heavy alloy (WHA) projectiles penetrating medium-carbon steel were conducted by using the ballistic gun and two-stage light-gas gun that can accelerate projectiles to impact velocities ranging from 1162 m/s to 2130 m/s. Depth of penetration (DOP) at elevated impact velocities of HEA and WHA projectiles were obtained firstly. Combined with the macroscopic and microscopic analysis of the residual projectiles, the transition of the penetration mode of the WFeNiMo HEA projectile was identified systemically. The experimental results indicated that the penetration mode of the HEA projectile changes from self-sharpening to mushrooming with the increase of impact velocity, while for the WHA projectile, the penetration mode is always mushrooming. The microstructure of the residual HEA projectiles showed that the phases tangle with each other and the morphology of the microstructure of the phases differs in the two penetration modes. Besides, the evolution of shear bands and fractures varies in the two modes. The evolution of the microstructure of HEAs causes the sharp-pointed nose to disappear and the HEA projectile ultimately becomes blunt as the impact velocity increases.

Controlling interpenetration and flexibility behaviors is intriguing and fundamental for porous coordination polymers. We report exceptional interpenetration behaviors involving controllable partia...

Summary Cermets embrace the high hardness of a ceramic and the good ductility of a metal. Therefore, they potentially meet the ever-increasing demands of new materials for harsh environments in energy generation and conversion. However, cermet sintering faces many challenges, such as metal volatilization, grain coarsening, and poor wettability of the metal with the ceramic, which affect the microstructure and thus mechanical properties. Herein, we apply an ultrafast high-temperature sintering (UHS) method to sinter cermets at a high temperature in only seconds. The high temperature leads to good wettability of the metal with the ceramic, while the short sintering time limits the loss of metal components and accurately controls the grain growth. We demonstrate the UHS method using a model cermet composed of a Ni-based superalloy and aluminum oxide, where we obtain dense microstructure, minimal nickel loss, and uniform grain size. Owing to these merits, good mechanical properties and oxidation resistance are achieved.

Increasing the dielectric constant of polymer/sulfide ceramic composites by using wide-bandgap semiconducting sulfide ceramic fillers like ZnS is difficult because of their low interface polarization. To increase the dielectric constant, in this study, ternary polymer-based composite films were designed and fabricated using a hybrid filler consisting of shell-like ZnS particles and core-like V2C MXene particles. First, V2C MXene with a multi-layered structure was synthesized from the simplest raw materials followed by the in-situ hydrothermal growth of ZnS particles around the V2C particles. Then, binary polymer/ZnS and ternary polymer/V2C–ZnS composites were fabricated, and their dielectric, conductive, and electrical breakdown properties were investigated. Finally, the effect of interfacial bonding between the V2C and ZnS phases was investigated by density functional theory calculations, and the contribution of V2C/ZnS interfacial bonding to the higher dielectric constant of the ternary composites than that of the binary composites was explained. The ternary composites exhibited balanced electrical properties suitable for energy storage applications. The ternary composite with 10 wt% hybrid filler loading exhibited a high dielectric constant of ~52, a low dielectric loss of ~0.11 at 100 Hz, and a high electrical breakdown strength of ~202 MV m−1. This study paves the way for the facile fabrication of high-performance composite dielectrics for application in advanced capacitors.

Rare-earth elements (REEs) in industrial wastewaters have great value for recycling and reuse, but their characteristic of low concentration poses a challenge to an efficient enrichment from wastewaters. In recent years, thiometallates featuring two-dimensional layers have shown great potential in the enrichment of REEs via the ion-exchange process. However, investigations on thiometallates featuring three-dimensional anionic frameworks for the recovery of REEs have not been reported. Herein, K2Sn2S5 (KTS-2), a thiostannate possessing a three-dimensional porous framework, was chosen as an ion-exchange material for capturing REEs from an aqueous solution. Indeed, KTS-2 exhibited excellent ion-exchange performance for all 16 REEs (except Pm). Specifically, KTS-2 displayed a high capture capacity (232.7 ± 7.8 mg/g) and a short equilibrium time (within 10 min) for Yb3+ ions. In addition, KTS-2 had a high distribution coefficient for Yb3+ ions (Kd > 105 mL/g) in the presence of excessive interfering ions. Impressively, KTS-2 could reach removal rates of above 95% for all 16 REEs in a large quantity of wastewater with low initial concentration (∼7 mg/L). Moreover, KTS-2 could be used as an eco-friendly material for ion exchange of REEs, since the released K+ cations would not cause secondary pollution to the water solution.

The growing demand of wearable device and the irreplaceable roles in stealth technique have boosted the exploration of high-performance flexible microwave absorbers. Herein, a novel flexible honeycomb structural absorber (FHSA) of carbon fiber (CF)/polyamide (PA)/carbonyl iron (CIP) composite was successfully fabricated via selective laser sintering (SLS) 3D-printing. The CFs arrangement and unit-structure were rationally controlled during the SLS 3D printing process for acquiring enhanced microwave absorption (MA) property, especially for the high bending angles. Therefore, under the high bending angle of 150°, the minimum reflection loss of the designed FHSA can reach −47 dB at 16.2 GHz with a broadband absorption of 13.2 GHz, covering the whole C2, X, and Ku bands, which breaks the traditional restraints that the flexible absorbers can only have the high MA property in tiling or minor bending status. In addition, the FHSA also showed the advantages of highly flexible deformation, self-recovery and no-crease damage in repeated bending, which could largely improve the environment applicability. This work provides a controllable strategy for the design of flexible microwave absorber, showing potential applications in wearable functional devices and military stealth protection.

Reactive Materials (RMs), a new material with structural and energy release characteristics under shock-induced chemical reactions, are promising in extensive applications in national defense and military fields. They can increase the lethality of warheads due to their dual functionality. This paper focuses on the energy release characteristics of RM casings prepared by alloy melting and casting process under explosive loading. Explosion experiments of RM and conventional 2A12 aluminum alloy casings were conducted in free field to capture the explosive fireballs, temperature distribution, peak overpressure of the air shock wave and the fracture morphology of fragments of reactive material (RM) warhead casings by using high-speed camera, infrared thermal imager temperature and peak overpressure testing and scanning electron microscope. Results showed that an increase of both the fireball temperature and air shock wave were observed in all RM casings compared to conventional 2A12 aluminum ally casings. The RM casings can improve the peak overpressure of the air shock wave under explosion loading, though the results are different with different charge ratios. According to the energy release characteristics of the RM, increasing the thickness of RM casings will increase the peak overpressure of the near-field air shock wave, while reducing the thickness will increase the peak overpressure of the far-field air shock wave.

High dielectric response and low leakage conduction are desired in polymer/ceramic composite dielectrics for capacitive energy storage. Rational structural design of hybrid ceramic filler can lead to a balance between high dielectric constant and insulation in composites. In this study, high dielectric constant and breakdown strength were achieved in fluoropolymer/mesoporous silica@CdTe nanocomposite films. Mesoporous silica nanoparticles (MSNs) were employed owing to their high insulation and complex electron-leakage channel. CdTe quantum dots combined with pore-canal inwalls of MSNs were employed because of their internal exciton polarization and MSNs/CdTe interface polarization. Compared with polymer/MSNs composites, polymer/MSNs@CdTe composites exhibited remarkably improved dielectric constant, slightly increased dielectric loss, and slightly reduced breakdown strength. High dielectric constant of ternary composites was ascribed to exciton orientation inside CdTe and interfacial dipole orientation between MSNs and CdTe. High breakdown strength was attributed to high insulation in MSNs and long-range electron transfer inside MSNs@CdTe. An optimal ternary composite with 12 wt% MSNs@CdTe showed a high dielectric constant of ~56, low dielectric loss of ~0.19 at 100 Hz, and high breakdown strength of ~308 MV m-1. The results of this study can provide insights for enabling large-scale fabrication of modern composite dielectrics based on mesoporous particles@semi-conductive quantum dots fillers.

Effect of multiple repair welding has been investigated on the crack susceptibility and mechanical properties of Inconel 718 (IN718) alloy casting. The results show a dumbbell-shaped fusion zone (FZ) with thick ends and thin in the middle portion, depending on the number of repair welding cycles. The width and length of heat-affected zone (HAZ) cracks are significantly larger than that of FZ cracks, indicating that HAZ cracks are quite severe in multiple repair welding of IN718 alloy. HAZ cracks play a significant role in decreasing the mechanical properties. The stress rupture life sharply reduces after repair welding. The hardness of FZ is close to that of HAZ and base metal (BM) region, and only a minor decrease in hardness was found from BM to FZ after linear fitting. With the increase in repair welding times, the residual stress formed during welding increases gradually based on finite element analysis. The repair welding cracking is mainly controlled by local residual stress and crystal orientation based on this study. Both FZ and HAZ crackings increase with the increase in the number of repair welding cycles; thus, it must be limited to three for IN718 alloy casting.

An absorptive device for broadband low-frequency sound with ventilation is essential but challenging in acoustic engineering, which is subjected to the narrow-band limitation and difficulty of balancing high-efficiency absorption and excellent ventilation. Here, we have theoretically and experimentally demonstrated an ultra-sparse (with filling ratio of 53.7%) broadband metamaterial absorber which can efficiently absorb (absorptance >90%) sound energy ranging from 307 to 341 Hz, while enabling air to flow freely. The broadband absorber is constructed by parallel coupling four ventilated metamaterials absorbers (VMAs) showing different operating frequencies. Each VMA is composed of three folded Fabry–Perot resonators as paste components, which are patched subsequently to the walls of a waveguide and correspondingly act as dark, middle, and bright modes following the coupled mode theory. In the VMA, the dark mode is highly over-damped to absorb sound energy, while the bright mode is highly under-damped to be an effective acoustic soft boundary, and the middle mode in-between should be slightly over-damped to strengthen the absorptions. Further investigation demonstrates that broadband high-efficiency absorption is robust against oblique incident angles. The proposed VMA provides a clear scheme for efficiently absorbing low-frequency sound while allowing free air flow simultaneously, which may prompt versatile applications in noise control.

Current formulation development strongly relies on trial-and-error experiments in the laboratory by pharmaceutical scientists, which is time-consuming, high cost and waste materials. This research aims to integrate various computational tools, including machine learning, molecular dynamic simulation and physiologically based absorption modeling (PBAM), to enhance andrographolide (AG) /cyclodextrins (CDs) formulation design. The lightGBM prediction model we built before was utilized to predict AG/CDs inclusion's binding free energy. AG/γ-CD inclusion complexes showed the strongest binding affinity, which was experimentally validated by the phase solubility study. The molecular dynamic simulation was used to investigate the inclusion mechanism between AG and γ-CD, which was experimentally characterized by DSC, FTIR and NMR techniques. PBAM was applied to simulate the in vivo behavior of the formulations, which were validated by cell and animal experiments. Cell experiments revealed that the presence of D-α-Tocopherol polyethylene glycol succinate (TPGS) significantly increased the intracellular uptake of AG in MDCK-MDR1 cells and the absorptive transport of AG in MDCK-MDR1 monolayers. The relative bioavailability of the AG-CD-TPGS ternary system in rats was increased to 2.6-fold and 1.59-fold compared with crude AG and commercial dropping pills, respectively. In conclusion, this is the first time to integrate various computational tools to develop a new AG-CD-TPGS ternary formulation with significant improvement of aqueous solubility, dissolution rate and bioavailability. The integrated computational tool is a novel and robust methodology to facilitate pharmaceutical formulation design., Graphic abstract Image, graphical abstract

The shape of the gap is narrow and thin in low-speed wire electrical discharge machining (WEDM-LS) workpiece with large thickness; it is likely that a lot of debris cannot be removed out of the gap in time, or even accumulate somewhere, which causes a poor machining stability and low processing efficiency. In this paper, ultrasonic vibration (USV) and magnetic field (MF) complex–assisted techniques are combined with WEDM-LS to improve the machining performance. The velocity and pressure of the flow field in USV-assisted WEDM-LS are analyzed according to the theory of fluid mechanics. The fluid-solid coupling model of electrode wire and working fluid, the two-phase flow model of the working fluid, and the debris are established in COMSOL Multiphysics software, and the influence of different amplitudes on motion and distribution of debris is analyzed. It is indicated by the simulation results of debris motion that the exclusion rate of debris increases by 22.5% and the debris are distributed more evenly in the discharge gap. The experiment of a USV-assisted WEDM-LS machining workpiece with large thickness is conducted. It shows that the probability of abnormal electrical discharge reduces obviously and the distribution of discharge point is more uniform, which increases the pulse utilization and discharge efficiency. In addition, the material removal rate (MRR) increases by 44.4%, the surface roughness value (Ra) reduces by 12.8% on average, the number of debris recast to the surface decreases significantly, and the micro-cracks on the machined surface of the workpiece decrease in USV-assisted WEDM-LS.

In this study, micro-arc oxidation (MAO) coatings were prepared on a novel glass microsphere reinforced Mg alloy composite to retard the degradation of the composite in the liquid environment containing Cl− for degradable downhole tool applications. The microstructure and chemical composition of the coatings were characterized by SEM, EDS, XPS and XRD. The growth characteristics of the MAO coatings on different matrix regions were analyzed. The corrosion and wear resistance of the coatings were evaluated through the immersion test, electrochemical measurements and friction test. Results showed that the MAO coatings consisted primarily of Mg2SiO4, MgO, little amount of MgAl2O4 and amorphous SiO2. The current density influenced the thickness and structure via affecting the voltage response of the MAO process, afterward influencing the properties of the coatings. The termination voltage of the MAO process and thickness of the coatings increased with the current density. With the current density increased from 8 to 160 mA/cm2, the compactness and microhardness of the coatings were increased, thereby improving the corrosion and wear resistance of the coatings. However, as the current density increased to 200 mA/cm2, the generation of large through-cracks caused the friction coefficient to increase and the corrosion resistance to deteriorate.

In this paper, a novel composite process technology – Low Speed Wire Electrical Discharge Machining (WEDM-LS) with Vertical Ultrasonic Vibration (VUV) assisted is put forward to improve the perform...

The rapid and cost-effective quantitative characterization of broad-sense shale oil reservoirs is highly challenging due to the complex lithology and strong heterogeneity of the strata. In this paper, the pore structures and surface roughness of samples of various lithologies from a shale oil reservoir were studied using atomic force microscopy (AFM) and the open-source Gwyddion analytical software. The surface morphology was reconstructed both two-dimensionally and three-dimensionally using the AFM data for the mudstone, siltstone, and dolarenite in a broad-sense shale oil reservoir. The surface roughness was evaluated with respect to parameters such as the arithmetic average roughness, root mean square roughness, surface skewness, and kurtosis coefficient. The pores of various scales were quantitatively identified using the watershed algorithm. The samples were also evaluated using focused ion beam scanning electron microscopy for comparison, and the derived pore scales are consistent with those obtained from the AFM analysis. In conclusion, the utilization of AFM and open-source software provides a new easy-to-operate method, which can be widely applied to characterize the surface roughness and pore structures of unconventional oil and gas reservoirs.

Purpose Traditional simulation research of geological and similar engineering models, such as landslides or other natural disaster scenarios, usually focuses on the change of stress and the state of the model before and after destruction. However, the transition of the inner change is usually invisible. To optimize and make models more intelligent, this paper aims to propose a perceptible design to detect the internal temperature change transformed by other energy versions like stress or torsion. Design/methodology/approach In this paper, micron diamond particles were embedded in 3D printed geopolymers as a potential thermal sensor material to detect the inner heat change. The authors use synthetic micron diamond powder to reinforced the anti-corrosion properties and thermal conductivity of geopolymer and apply this novel geopolymer slurry in the direct ink writing (DIW) technique. Findings As a result, the addition of micron diamond powder can greatly influence the rheology of geopolymer slurry and make the geopolymer slurry extrudable and suitable for DIW by reducing the slope of the viscosity of this inorganic colloid. The heat transfer coefficient of the micron diamond (15 Wt.%)/geopolymer was 50% higher than the pure geopolymer, which could be detected by the infrared thermal imager. Besides, the addition of diamond particles also increased the porous rates of geopolymer. Originality/value In conclusion, DIW slurry deposition of micron diamond-embedded geopolymer (MDG) composites could be used to manufacture the multi-functional geological model for thermal imaging and defect detection, which need the characteristic of lightweight, isolation, heat transfer and wave absorption.

In nanoporous materials, guest–host interactions affect the properties and function of both adsorbent and adsorbate molecules. Due to their structural and chemical diversity, metal-organic frameworks (MOFs), a common class of nanoporous materials, have been shown to be able to efficiently and, often, selectively adsorb various types of guest molecules. In this study, we characterize the structure and dynamics of water confined in ZIF-90. Through the integration of experimental and computational infrared (IR) spectroscopy, we probe the structure of heavy water (D2O) adsorbed in the pores, disentangling the fundamental framework–water and water–water interactions. The experimental IR spectrum of D2O in ZIF-90 displays a blue-shifted OD-stretch band compared to liquid D2O. The analysis of the IR spectra simulated at both classical and quantum levels indicates that the D2O molecules preferentially interact with the carbonyl groups of the framework and highlights the importance of including nuclear quantum effects and taking into account Fermi resonances for a correct interpretation of the OD-stretch band in terms of the underlying hydrogen-bonding motifs. Through a systematic comparison with the experimental spectra, we demonstrate that computational spectroscopy can be used to gain quantitative, molecular-level insights into framework–water interactions that determine the water adsorption capacity of MOFs as well as the spatial arrangements of the water molecules inside the MOF pores which, in turn, are key to the design of MOF-based materials for water harvesting.

The dynamic performances of a polyurethane-reinforced ballast bed and an unreinforced ballast bed at an operation site were tested by using the impact excitation technique. The influences of the ballast beds with and without polyurethane reinforcement on the natural frequency were investigated, along with the vertical and longitudinal vibration transmission characteristics of the track structure. The results show the following. Compared to the ballast bed, the polyurethane ballast bed has an inhibitory effect on the rail vibration in the range of 200–400 Hz, but there is an increased rail vibration amplitude in the higher frequency range. The polyurethane-reinforced ballast bed significantly increases the amount and amplitude of the dominant vibration frequencies of the sleeper. As the frequency increases (> 90 Hz), the superstructure of the polyurethane track rapidly transfers from being flexible to rigid, and the track thus absorbs and dissipates the impact load, quickly damping the vibration in the range of 90–470 Hz. The calculation results of the displacement transmission ratio (DTR) proposed in this study also support this finding, suggesting the use of DTR to more intuitively evaluate the vibration damping effect of each component of the track. The polyurethane material reinforces the ballast bed rather than the damping vibration, thereby improving the stability of the track structure.

In this research, cast magnesium alloys AZ31-xGd are assessed as anode material candidates for primary Mg-air batteries. The effects of Gd content in the microstructure, discharge behavior and electrochemical properties of cast AZ31 as an anode are studied through microstructure characterization, electrochemical measurements and battery discharge tests. Results indicate that the introduction of Gd can refine α-Mg grains. The discharge and electrochemical properties of magnesium alloys are improved by optimizing its composition. We confirm that the Al2Gd can restrain the kinetics of hydrogen evolution reaction. The acicular structure can connect the magnesium alloy matrix and reduce the chunk spalling. The data suggest that AZ31-5.8Gd alloy has the best self-corrosion resistance performance and discharge behavior among all prepared AZ31-xGd alloys. AZ31-5.8Gd can output a high specific capacity of 1411.8 mAh g−1 and a high energy density of 1153 mWh g−1 at the current density of 40 mA cm−2. The anode efficiency can reach up to 63.21%. The addition of Gd properly can optimize magnesium alloy microstructure and improve the discharge performance.

This paper investigates the spatial distributions of electron beam-evaporated atoms and electron beam-induced plasma in the coating process. The materials evaporated by electron beams first form vapour and then a little of plasma is generated in the vapour. The spatial distributions of electron beam-induced atoms and plasma play an important role on the coating uniformity of composition and thickness. The radial distribution of coating deposition thickness of electron beam-evaporated atoms predicted by this study agrees with the available experimental data. The predicted distribution of ion density in the electron beam-induced plasma agrees with the available measured data. The results reveal that the normalized coating thicknesses at the divergence angle of 6 and 14 degrees of vapor source, respectively, are 0.8 and 0.2 of these at divergence angle of 0 degree of vapor source for titanium and aluminum evaporated separately. The similar tendency for the decreasing coating thickness with the radial distance is also obtained for the co-evaporation of aluminum, titanium, and copper. High rotation rate of substrate of vapor source leads to the small deposition rate. Most ions in the electron beam-induced plasma are attracted by electrons of the electon beam and are located at the neighbourhood of the beam region. Therefore, the ion and ion-attracted electron densities rapidly decrease with the increasing radial distance from the electron beam.

In order to investigate the deterioration of microstructure in service, the intrinsic microstructural stability and performance of DD6 during long-term aging without an external load are investigat...

The spatial vibration model of the electrode wire in ultrasonic vibration (USV)-assisted low-speed wire electrical discharge machining (WEDM-LS) under continuous discharges is proposed for analyzing its vibration state, and subsequently, a theoretical model of material removal from the TiNi-01 shape memory alloy workpiece is established by means of Gaussian heat source in single-pulse discharge process and the principle of the nearest-point discharge breakdown. Then, the topological matrix of the surface morphology is developed for investigating the surface characteristics and the distribution of discharge points by simulation. Finally, the experiment of photographing the discharge channel position is accomplished to validate the reliability and feasibility of the model. The results show that the discharge channels are more uniformly distributed in the hybrid process, which enhance effectively the success rate of the discharge pulses and decrease the surface roughness. In addition, a mathematical model to evaluate the uniformity of the discharge point distribution is employed as an evaluation index of the burn degree on the workpiece surface. The distribution uniformity coefficient obtained by the compound process is higher than that of the traditional WEDM-LS. This is consistent with the phenomenon of alleviated surface burn under the hybrid machining technology, and the average errors of the simulated and experimental values of the uniformity coefficient of traditional WEDM-LS and the hybrid process are 4.9% and 3.4%, respectively. The maximum errors of surface roughness between simulated value and experimental value about the WEDM-LS and hybrid process are 7.4% and 8.2%, respectively. It is demonstrated that the model can effectively and accurately predict the surface roughness and the surface burn of the workpiece.

Atomic layer deposition (ALD) of the iron-group transition-metal diselenides FeSe2, CoSe2, and NiSe2 is reported for the first time. The ALD processes employ the associated metal amidinates as the ...

Relaxor ferroelectric ceramics are good candidates for capacitor, sensor and actuator applications because of their high dielectric permittivity, high piezoelectric constant and high value of field induced strain, respectively. However, their dielectric loss is usually relatively high, which is a problem for actual applications. The introduction of the high entropy concept opens up the possibility of developing new multi-element relaxor-like ferroelectric materials with short-range ordered polar structures having short relaxation times to decrease their loss. Here we present a new high entropy A-site disordered perovskite (Pb0.25Ba0.25Sr0.25Ca0.25)TiO3 relaxor-like ferroelectric. Moreover, the ceramic has low loss (

Cancer cells can be killed by magnetic-nanoparticles-induced hysteresis heat under an external alternating magnetic field. However, the hysteresis heat-induced temperature must be precisely controlled to prevent damages to the ambient normal tissue from cancer cells. Therefore, this study employs a heat model to analyze the variation of temperature with time in magnetic nanoparticles within cancer. Results show that the temperature increase with time predicted from this study is consistent with the available experimental data. The effect of anisotropy constant on temperature rise with time is presented. The anisotropy constant makes the behaviours of temperature variation significantly different.

Magnetic field-assisted low-speed wire electrical discharge machining (MF-assisted WEDM-LS) is an effective technique to improve the surface quality of the workpiece. This paper presents a successive removing model to predict kerf width and the surface topography of nickel–titanium (Nitinol) shape memory alloy in different parameters. Firstly, the motion of an electron was calculated in the magnetic field. It could be obtained that if the length of the discharge channel path was the same with the condition that in traditional WEDM-LS, the width of the discharge gap was decreased because of the deflection of the electron trajectory caused by the magnetic field. Then, a modified gauss heat source equation was derived by calculating the incident angle of the discharge channel. Based on the principle of conservation of energy, the shape of the crater in different parameters was emulated. Moreover, an electrothermal coupling model was established to investigate the surface formation in the successive discharges process. The simulation results show that the average value of the surface roughness of the workpiece in WEDM-LS with magnetic field assisted was decreased by 12.3% compared with that in traditional WEDM-LS. Eventually, experiments of kerf and surface quality were carried out respectively. The experimental results showed that the kerf decreased from 376.2 to 361.7 μm in the magnetic field intensity of 0.4 T. The surface topographies of the workpieces showed good agreement with the simulation results, and the average relative error of surface roughness between simulated results and experimental results is 8.7%.

In the family of inorganic perovskite solar cells (PSCs), CsPbBr3 has attracted widespread attention due to its excellent stability under high humidity and high temperature conditions. However, power conversion efficiency (PCE) improvement of CsPbBr3-based PSCs is markedly limited by the large optical absorption loss coming from the wide band gap and serious charge recombination at interfaces and/or within the perovskite film. In this work, using density functional theory calculations, we systemically studied the electronic properties of niobium (Nb)-doped CsPbBr3 with different concentration ratios. As a result, it is found that doped CsPbBr3 compounds are metallic at high Nb doping concentration but semiconducting at low Nb doping concentration. The calculated electronic density of states shows that the conduction band is predominantly constructed of doped Nb. These characteristics make them very suitable for solar cell and energy storage applications.

A series of Fe-modified bimetallic Fex–Ni1−x-MOFs catalysts were successfully synthesized by solvent thermal method for CO-SCR. A significant activity improvement was found over bimetallic MOFs with the highest NOx conversion of 100% achieved on Fe0.33–Ni0.67-MOFs at 230 °C. The promoted low-temperature SCR activity was attributed to large surface area, directional growth of rod structure and greater surface oxygen mobility. The enhanced adsorption and transformation ability of CO and NO were further found due to relatively high concentration of Fe3+/Fe2+ formed due to redox cycle (Fe2+ + Ni3+ ↔ Fe3+ + Ni2+). Fe sites were found to be strong storing sites for NOx species helping to anchor more nitrates. A special Fe–Ov–Ni structure was formed between Fe and Ni, which can weaken N–O bond and generate more bridging nitrate, especially key intermediates trans-N2O2− species at low temperature. These features played a crucial role at low temperature and therefore achieved a superior activity.

Photodynamic therapy (PDT) is a promising strategy for cancer treatment. It can not only generate reactive oxygen species (ROS) to cause the chemical damage of tumor cells in the presence of enough oxygen but also promote the antitumor immunity of T cells through enhancing the production of interferon γ (IFN-γ). However, one phenomenon is ignored so far that the enhanced production of IFN-γ caused by PDT may significantly increase the expression of programmed death-ligand 1 (PD-L1) on the tumor cell membrane and thus could inhibit the immune killing effects of T cells. Herein, we report the construction of a composite by loading metformin (Met) and IR775 into a clinically usable liposome as a two-in-one nanoplatform (IR775@Met@Lip) to solve this problem. The IR775@Met@Lip could reverse tumor hypoxia to enhance ROS production to elicit more chemical damage. Besides, the overexpression of PD-L1 by PDT was also effectively down-regulated. These therapeutic benefits including decreased PD-L1 expression, alleviated T cell exhaustion, and reversed tumor hypoxia successfully suppressed both the primary and abscopal tumor growth in bladder and colon cancers, respectively. Combining with its excellent biocompatibility, our results indicate that this IR775@Met@Lip system has great potential to become a highly effective cancer therapy modality.

In this research, the effect of two different per centages of silicon, i.e. 0.08 and 0.3 wt-%, on microstructure and stress rupture life of a Ni-based superalloy was investigated. The results showe...

Estimating the required homogenization time during post-heat treatment after alloy fabrication is critical for both casting and additive manufacturing (AM). In this work, three CALPHAD-based modeling approaches to estimate the homogenization time in order to dissolve the Laves_C14 phase into γ matrix are evaluated for Inconel 718 alloys made by suction casting and laser powder bed fusion. These values are compared with the homogenization at 1180 °C for different durations. The compositions of the γ matrix obtained from experiments are used as inputs for the first model. The first model involves single-phase diffusion simulations using the diffusion module (DICTRA) implemented in the Thermo-Calc software package with composition profile for the Laves_C14 phase either determined from experiments or calculated by the lever rule. The second model uses Scheil simulations for predicting the segregation profiles, which are used as inputs for single-phase simulations. In the third model, moving boundary simulations using DICTRA are performed using the composition of Laves_C14 phase from the lever rule. The homogenization time determined using the first model matches reasonably well with the experimental observation for the AM alloy. The second model is imprecise as the segregation from Scheil calculation is not reliable for AM alloy. The last model is inaccurate due to lack of mobility data for atomic diffusion in the Laves_C14 phase. The predicted homogenization times for the cast alloys using these models do not match with the experimental values. This necessitates the need for determining the mobilities for Laves_C14 phase for improving the accuracy of DICTRA simulations to estimate the homogenization time.

In an attempt to enhance the low-temperature dischargeability of A2B7-type hydrogen storage alloy, the addition of alane (AlH3) by convenient ball milling method was investigated based on La-Y-Ni superlattice alloy containing Y2Ni7-type phase and YNi3-type phase primarily. The maximum discharge capacity of the composite with doping 1 wt.% AlH3 increased by 364.2% reaching 208.9 mAh g−1 at 233 K compared with the pristine sample. The initial high-rate discharge capacity of doping 1 wt.% AlH3 sample reached 151.7 mAh g−1 at 4000 mA g−1 current density. The improvement could be ascribed to strengthening of hydrogen diffusion channel and acceleration of H-kinetics at low temperatures derived from formation of new porous structure and modification of lattice defects by dissolution of aluminum on the surface. It has made a powerfully contribution to a pace of commercialization of A2B7-type superlattice hydrogen storage alloy applying in high altitude or latitude regions.

Dynamic molecular materials, which involve mechanical motions in crystals, usually exhibit tunable properties related to conformational polymorphs. Herein, we describe a solvent-free molecular crys...

Memristors are regarded as one of the key devices to break through the traditional Von Neumann computer architecture due to their capability of simulating the function of neural synapses. Among various memristive materials, two-dimensional (2D) materials are promising candidates to build advanced memristors with extremely high integration density and low power consumption. However, memristors based on 2D materials usually suffer from poor endurance and retention due to their vulnerability to material degradation during the formation/fusing processes of conductive filament channels within the switching media of 2D materials. Here, a new memristor architecture based on a WS2/MoS2 2D semiconducting heterojunction (metal/heterojunction/metal, MHM) is proposed, which is completely different from the conventional metal/insulator/metal (MIM) sandwich structure. Through the introduction of a type-II 2D heterojunction, a resistance switching mechanism based on band modulation rather than the conductive filaments can be realized to eliminate the material degradation during the set/reset processes. A prototype MHM memristor based on the WS2/MoS2 heterojunction is successfully developed with a large switching on/off ratio up to 104 and a clearly extended endurance over 120 switching cycles, showing the advantage of the 2D WS2/MoS2 heterojunction over the individual MoS2 or WS2 layers in memristive performance. The proposed method for the MHM-type 2D memristor has the potential to achieve a large-scale integrated memristor matrix with low power consumption and high integration density, which is promising for future artificial intelligence and brain-like computing systems.

Extending new families of ABX3-type three-dimensional (3D) molecular perovskites based on diverse X-site molecular ligands is of interest in designing advanced hybrid materials for wide usage. Being a pseudo-halogen ligand, the thiocyanate anion is expected as an X-site bridge to construct 3D molecular perovskites, but has only yielded two pure inorganic instances so far. Herein, we report four new 3D SCN−-bridged molecular double perovskites with a general formula of A2[CdM′(SCN)6] (A/M′ = K+/Ni2+, Me2NH2+/Ni2+, Me2NH2+/Mn2+, Me3S+/Cd2+), including three unprecedented hybrid instances incorporating organic cations. A detailed comparison between these SCN−-bridged molecular perovskites and some azido-bridged analogues, on their host–guest interactions and structural distortions, revealed that the bent Cd–S–C angles in these SCN−-bridged molecular perovskites vary in a narrow range, endowing their frameworks with a high structural distortion and a relatively strong structural rigidity. The present study not only extends SCN−-bridged 3D molecular perovskites to enrich the perovskite family, but also paves a way for the rational design of new molecular perovskites.

An unprecedented A2MIMIIIX6-type double perovskite adopting a fully hexagonal BaNiO3-type structure, (piperidinium)2[KBiCl6], undergoes a 2/mF ferroelastic phase transition at 285 K with a spontaneous strain of 0.0615, arising from the order–disorder transition of organic cations together with the synchronous displacement of inorganic chains.

C–H bond activation and dehydrogenative coupling reactions have always been significant approaches to construct microscopic nanostructures on surfaces. By using scanning tunneling microscopy/spectroscopy (STM/STS) and non-contact atomic force microscopy (nc-AFM) combined with density functional theory (DFT), we systematically characterized the atomically precise topographies and electronic properties of H2TPP cyclodehydrogenation products on Au(111). Through surface-assisted thermal excitation, four types of cyclodehydrogenation products were obtained and clearly resolved in the nc-AFM images. The electronic characterization depicts the predominant resonances and their spatial distributions of the four products.

Interface passivation plays a pivotal role in achieving high-efficiency organic metal halide perovskite solar cells (PSCs). It has been recently revealed that atomic layer deposition (ALD) of wide-band gap oxides shows great potential to effectively passivate defects at the interface, and ALD is also of great technological promise for industrial upscaling. However, the conflicting observations of ALD passivation are often reported in the literature, even with very similar ALD conditions. To unveil the involved crucial mechanism, this work carefully investigates the evolution of a representative MAPbI3 perovskite surface during the ALD of Al2O3, by employing the technique of in situ X-ray photoelectron spectroscopy. The ALD at 125 °C was found to cause significant degradation of the perovskite; lowering the deposition temperature can largely minimize the degradation, and 75 °C was found to be the best ALD temperature. Following this conclusion, inverted planar perovskite solar cells were prepared in ambient conditions with ALD Al2O3 interlayers. Indeed, cells with the interlayer deposited at 75 °C exhibited a significantly enhanced power conversion efficiency from 18.8% (champion 19.2%) to 20.0% (champion 20.4%). Photoluminescence measurements further evidence that the ALD layer can effectively passivate defect states at the perovskite surface. Considering the great representativeness and broad applicability of MAPbI3 and ALD Al2O3, the mechanism and strategy reported herein should be of significant value for the perovskite interface engineering in general.

Solid-state electrolytes (SSEs) are promising alternatives to traditional liquid electrolytes because of their safety issues. However, polymer SSEs have low ionic conductivity and weak mechanical strength, and inorganic SSEs are very brittle and unstable to lithium metal and atmospheric moisture, which restricts their practical applications. To avoid these disadvantages, it is essential to develop polymer–inorganic composite SSEs. In this work, we for the first time construct a solid composite polymer electrolyte of poly(vinylidene fluoride hexafluoropropylene) (PVDF-HFP) blended with Li1.3Al0.3Ti1.7(PO4)3 and flower-like CeO2 particles enriched with oxygen vacancies as inorganic fillers. The composite SSEs exhibit a wide electrochemical window of 5.1 V (vs. Li/Li+) and high ionic conductivity of 1.66 × 10−3 S cm−1 at room temperature. The conductivity enhancement originates from the oxygen vacancies associated with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) for releasing more lithium ions, and CeO2 is also beneficial for the suppression of Li dendrites. The solid-state LiFePO4/SSE/Li cell exhibits superior electrochemical performance at room temperature, the capacity is as high as 166.6 mA h g−1 at 0.1C, and the cell can sustain 83.1 mA h g−1 at 2C after 1000 cycles.

It is impossible to study the relationship between water damage and voidage of asphalt pavement because the voidage of pavement core sample cannot be determined accurately. Based on the industrial computed tomography (CT) scanning technology for core samples of real void fraction measurement, dynamic water flushing apparatus to water damage damage of core samples, the CT scan void fraction and destruction after the relationship between splitting strength and CPN rutting depth of core samples, respectively, set up different lanes of void fraction and cleavage strength and the fitting formula of rut depth.

Wearing surgical masks is one of the best protective measures to protect humans from viral invasion during the 2019 coronavirus (COVID-19) outbreak. However, wearing surgical masks for extended periods will cause uncomfortable sweltering sense to users and are easy to breed bacteria. Here, we reported a novel fibrous membrane with outstanding comfortability and antibacterial activity prepared by PP ultrafine fiber nonwovens and antibacterial functionalized h-BN nanoparticles (QAC/h-BN). The thermal conductivity of commercial PP nonwovens was only 0.13 W m-1 K-1, but that of the QAC/h-BN/PP nanocomposite fibrous membranes can reach 0.88 W m-1 K-1, an enhancement of 706.5% than commercial PP nonwovens. The surface temperature of commercial PP surgical masks was 31.8 °C when the wearing time was 60 min. In contrast, QAC/h-BN/PP surgical masks can reach 33.6 °C at the same tested time, exhibiting stronger heat dissipation than commercial PP surgical masks. Besides, the antibacterial rates of QAC/h-BN/PP nanocomposite fibrous membranes were 99.3% for E. coli and 96.1% for S. aureus, and their antibacterial mechanism was based on "contact killing" without the release of unfavorable biocides. We think that the QAC/h-BN/PP nanocomposite fibrous membranes could provide better protection to people.

Effect of solution treatment on the micropore and mechanical properties is investigated for the DD6 superalloy. The results show that solution treatment has positive and negative effects on the DD6...

In order to study the effect of catalysts’ morphology on the electrochemical reduction of nitrogen gas, sample catalysts of NiO with four different morphologies (hollow spherical, sea urchin-shape, cubic block, and rod-like) were prepared. Characterization of the NiO catalysts was carried out using SEM, BET, XRD and electrochemical investigation techniques. The results indicated that the nitrogen reduction reaction (NRR) is strictly dependent on the morphology of the NiO catalysts, as the hollow spherical NiO showed the best electrochemical NRR performance of NH3 yield rate (3.21 μg h-1 mg-1cat., 4.19 × 10-11 mol cm-2 s-1) and Faradaic efficiency (1.37%), which was higher than the yields and efficiencies of the rod-NiO (1.8 μg h-1 mg-1cat., 3.24 × 10-11 mol cm-2 s-1, 1.17%), sea urchin-NiO (1.66 μg h-1 mg-1cat., 2.44 × 10-11 mol cm-2 s-1, 1.08%) and cubic block-NiO (1.32 μg h-1 mg-1cat., 2.14 × 10-11 mol cm-2 s-1, 0.81%), respectively. These results match the order of the specific surface area of the NiO samples, with hollow spherical (113.91 m2 g-1) > rod-NiO (55.12 m2 g-1) ≈ sea urchin-NiO (55.29 m2 g-1) > cubic block-NiO (38.57 m2 g-1). This correlation can be attributed to the fact that large specific surface areas can provide more active sites for electrocatalysis. This work demonstrates the effect of the morphology of the NiO catalysts on its electrochemical NRR properties, which could offer some opportunity for the preparation of new electrode materials with improved electrocatalytic properties.