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This paper proposes some effective approaches to address the inherent issues of consequent-pole (CP) permanent magnet (PM) machines, such as saturation of the salient rotor core and unipolar PM leakage flux of the end region caused by asymmetric field. The effect of CP Halbach PM array with different magnetization direction and parameters that affect the saturation have been investigated for the CP PM machine with short pole pitch. By employing the CP Halbach array, the saturation issue can be solved and superior performance can be obtained without reducing the PM pole arc. In addition, unequal and multistep staggered rotors with magnetic barriers have been proposed to reduce the unipolar leakage flux in the end region. Compared with regular staggered rotors, not only better electromagnetic performance can be achieved, but also the end unipolar leakage flux can be reduced. Finally, a prototype is manufactured and the predictions have been validated by measurements.

Lithium (Li) metal is an attractive anode material with high capacity (3860 mAh g−1) and low potential (−3.04 V vs. standard hydrogen electrode) that shows highly promising for applications requiring high energy density. However, the low electrochemical potential of Li metal makes it extremely reactive and inevitably forming a native oxidized layer in the ambient environment and repeatedly being consumed when exposed to liquid electrolytes. It is therefore beneficial to replace the poorly controlled native passivation layer with a tailored artificial SEI to improve interface management between Li and electrolyte and enhance the stability of Li metal battery. Here, we use an integrated glovebox-atomic layer deposition (ALD)- X-ray photoelectron spectroscopy (XPS) setup to in-situ investigating the pristine Li surface and the surface composition after Ar, H2, O2, N2 and NH3 plasma treatment processes. We find that the pristine Li foil is naturally being covered with a native oxidized layer, which is mainly composed of LiOH, Li2O and Li2CO3. These investigated plasmas can efficiently remove the oxidized layer from the Li metal surface, in which metallic Li surface is obtained after Ar or H2 plasma treatments, where Ar plasma is more efficient. While O2 plasma treatment produces a Li2O layer, and N2 or NH3 plasma treatment leads to a Li3N (including a certain amount of LiON) layer on the Li surface. When employing the representative metallic Li (by Ar plasma treatment), Li2O layer coated Li (by O2 plasma treatment) and Li3N layer coated Li (by N2 plasma treatment) foils as electrodes in symmetric Li metal batteries, the Li3N coated Li electrode exhibits much higher stability than that of metallic and Li2O layer coated Li foils. Improved electrochemical performance has also been achieved in LiMn2O4 (LMO)||Li full cells using Li anode with Li3N protective coating layer. Our work reveals the detailed process of surface engineering of Li metal anodes with plasma treatments by in vacuo XPS, which may also be extended to other gas-treatment or plasma-treatment for stabilization of high energy density Li metal anodes and other metal-based anodes.

CrAlN coatings were synthesized on pre-plasma nitrided M2 high speed steels using different ion current densities. The effect of plasma nitriding pretreatment on the microstructures and tribological properties of composite CrAlN coatings had been studied. The results showed that the nitriding efficiency could be significantly enhanced by higher ion current density. The thickness of nitrided layer increased from 43 μm to 63 μm with the increase of ion current density. The nitrided layers without either compound layer or grain boundary precipitation were produced with all experimental ion current densities. Radial cracks also appeared at the Rockwell-C indentation edge of the composite CrAlN coating due to the conformal effect. Moreover, radial cracks of the composite coatings originated from the hard and brittle nitrided layer. The highest interfacial adhesion of the composite CrAlN coating reached 105 N. Furthermore, the wear resistance of CrAlN coating was improved by combining nitriding pretreatment with coating deposition, and the composite coating (PN4/CrAlN) possessed the superior wear resistant.

The butanone sensor based on metal oxide semiconductor (MOS) are anticipated with a high response and a low detection limit through a simple process. In order to solve the issue of insufficient sensing performance of a pure metal oxide, high selective ZnO sensor with ppb detection limit are successfully prepared by convenient hydrothermal method, moreover, the particle size of materials is adjusted by calcination temperature based on the Deby length for optimizing the sensor performance. All sensors are tested for response in the concentration range of 0.2 ppm to 100 ppm butanone. When the particle size is closer to 2 times the Debye length, the material exhibits a higher response to 100 ppm of butanone at the optimum operating temperature. In particular, the synthesized M-ZnO-400 sensor has a response 151 to 100 ppm butanone at 310 °C, with the detection limit of 200 ppb, the response time of 4.5 s, as well as the recovery time of 5 s. It is worth noting that response of the prepared sensor to butanone is at least 62 times higher than that of chlorobenzene, vinyl benzene, xylene, toluene, benzene, acetaldehyde and formaldehyde. In addition, the population analysis for the different bonds of the target gases are calculated by first principles simulation to further explain the high selectivity of butanone.

Aluminophosphate with |Hada|6[Al6(PO4)8](H2O)11 (denoted as ZHKU-1) of a new two-dimensional (2D) layer has been synthesized by adopting the template of alkylated memantine. The structure of ZHKU-1 was constructed from the alternate connection of AlO4 and triply bridged PO4 tetrahedra ([O=PO3]3-) with the P/Al ratio of 4:3. The inorganic layers are linked and separated by protonated amine molecules and H2O molecules through extensive H-bonds to give a supervoid of 19.6 A, contained an AAAA-stacked sequence along the b axis. The open framework of ZHKU-1 has adapted for encapsulating silver nanoparticles through photodeposition, forming the catalyst of Ag@ZHKU-1. The HRTEM images reveal the highly uniform Ag clusters with visually observed sizes of 1.9 nm. Moreover, Ag@ZHKU-1 has shown an efficient conversion of 99.3% within 75 s for catalytic reduction of 4-nitrophenol. This remarkable catalytic activity of Ag@ZHKU-1 can attribute to the large exposed surface and confinement effect of the 2D aluminophosphate of ZHKU-1.

To comprehensively understand the CO poisoning effect on high-temperature PEMFC stack (HT-PEMFCs), a 3-D numerical HT-PEMFCs model is developed. The crucial anodic kinetic parameters are obtained from experimental data to improve the accuracy of the model. Then, multi-perspective analysis is conducted on different HT-PEMFC stacks with 1, 3, and 5 cells working at 160 °C with 3 mol% CO in H2. Besides, parametric simulations are conducted on the three-cell stack. It is found that the CO and H2 coverage varies between cells in the stack due to the temperature distribution difference, and the stack with more cells as well as the middle-cell of multi-cell stack have better performance, higher H2 coverage, lower CO coverage due to higher internal temperature. However, too high local temperature not only reduce the CO coverage but reduce the H2 coverage and increase the anode overpotential. The resistance to CO poisoning can be improved by increasing operating temperature, but when CO2 and water vapor are introduced into the anode, the H2 coverage decreases and the CO coverage increases due to the decrease of H2 concentration. The study clearly demonstrated that high performance and high CO resistance can be achieved by carefully regulating the operating conditions.

The configurational space of two-dimensional planar sp2 carbon has been systematically scanned by a random strategy combined with group and graph theory, and 1114 new carbon allotropes have been identified. These allotropes are energetically more favorable than most of the previously predicted 120 carbon allotropes. By fitting the HSE06 band structures of six old structures, we optimize the parameters for a general and transferable tight-binding model for high-throughput band structure calculations. We identified that there are 190 Dirac semimetals, 241 semiconductors, and 683 normal metals among the new allotropes. Interestingly, several stable low-energy carbon systems with exotic electronic properties are proposed, such as type III, type I/II mixed, and type I/III mixed semimetals, which are very rare in planar carbon systems. In particular, one nodal-line semimetal has been discovered among these thousands of allotropes, which is the first nodal-line semimetal in sp2 carbon systems. Our discoveries greatly enrich our knowledge of the structures and electronic properties of the two-dimensional carbon family.

In this study, a heat pump drying (HPD) system platform complemented by solar hot water was designed and established. The objective was to address the declines in the heating performance of air source HPD at high altitudes (more than 3000 m), cold conditions (annual average temperature at 5 °C), and with large temperature differences between day and night (more than 20 °C), i.e. under harsh conditions. A theoretical model was derived to determine the system parameters and to support the experimental analysis. Under no-load conditions, four cases with ambient temperature were tested and compared to explore the relationships between the system parameters and performance, as well as the effectiveness of the supplementary solar hot water. The heating performances under HPD and solar-assisted HPD (SHPD) modes were compared and analysed under load conditions (930 kg Mu Xiang). The results indicate that a decrease in the ambient temperature and increase in the temperature in the drying room causes attenuations of the compressor mass flow rate, evaporator cooling power, condenser heating power, and system coefficient of performance (COP). In addition, solar water heating can significantly improve the heating performance of the HPD system. Under no-load conditions, the average heating power of the HPD-mode system is 19.27 kW, and the average COP is 2.76. The average heating power of the SHPD mode system is 23.34 kW, and the average COP of the system reaches 3.24, an increase of 17.4%. Under load conditions, the average heating capacity power of the HPD mode is 9.64 kW; the COP is only 1.34, and fluctuates significantly with the decrease in ambient temperature. The average heating capacity power of the SHPD mode is 17.62 kW and the COP is 2.42, i.e. 1.8 times of that of the HPD mode. By raising the drying room temperature to the same set temperature, the SHPD mode time is shortened by 70%.

Voltage stability is one of the critical factors for the stable operation of DC microgrids (MG). For the communication free DC MG, the DC voltage is more vulnerable due to the DC voltage deviation caused by the droop characteristics. When facing the transient power fluctuation caused by multiple electric vehicles (EVs) connected to the grid, PV shedding, etc., the DC bus will have a large voltage sag. The voltage quality degradation will bring adverse effects to the DC MG. However, most energy storage systems like battery energy storage systems (BESS) are not suitable for suppressing transient large power fluctuation. In this paper, the SMES is introduced to a DC MG to form a power regulation system. A voltage-based segmented (VBS) control is designed for the SMES-based power regulation system to suppress transient large power fluctuation in the DC MG. The voltage deviation caused by power distribution can be tolerant by VBS controlled SMES. Meanwhile, the dynamic recovery capability of the DC voltage is improved. The control method of SMES is independent of other devices in DC MGs, hence it is not dependent on communication. The control strategy of the SMES is further verified by simulation results.

The flashover along epoxy spacer installed in 1 MV DC GIL caused by the excessive concentration of electric field threatens the safe operation of the ITER NBI (neutral beam injector). A spacer with surface conductivity gradient has been proposed to optimize the electric field distribution. In this paper, a simplified model of transmission pipeline with spacer is established. It is found that the electric field is mainly concentrated on the high voltage triple junction and the turning position of spacer. The surface conductivity gradient distribution on the spacer is designed by an iterative method. Results indicate that surface conductivity gradient can weaken the electric field distortion on both sides of spacer, especially the electric field strength of turning position of the concave surface is decreased obviously compared with that of the conventional spacer.

Although super-resolution imaging offers an opportunity to visualize cellular structures and organelles at the nanoscale level, cellular heterogeneity and unpredictability still pose a significant challenge in the dynamic imaging of live cells. It is thus vital to develop better-performing and more photostable probes for long-term super-resolution imaging. Herein, we report a probe, LD-FG, for imaging lipid droplet (LD) dynamics using structured illumination microscopy (SIM). LD-FG allows wash-free imaging of LDs, owing to a hydrogen-bond sensitive fluorogenic response. The replacement of photobleached LD-FG by intact probe molecules outside the LDs ensures the long-time stability of the fluorescence imaging. With this buffering fluorogenic probe, fast and unpredictable dynamic processes of LDs can be visualized. Using this probe, two LD coalescence modes were discovered. The dynamic imaging also allowed us to propose a new model of LD maturation during adipocyte differentiation, i.e., a fast LD coalescence followed by a slow ripening step. The excellent performance of LD-FG makes the buffer strategy an effective method for designing fluorescent probes for cell dynamic imaging.

The improved high-performance polymer cement mortar (PCM) and glass fiber reinforced plastic (GFRP) system reinforcement was used in the research to strengthen and repair the masonry structure, so as to improve its bond stress, anchoring force, and integral performance without changing the original structure and further study the shear performance of masonry structure strengthened by the combination of the two. The optimum ratio of improved high-performance PCM was determined by analyzing the bend-press ratio of PCM test block. Improved high-performance PCM and GFRP were combined to strengthen the damaged masonry wall, and a five-piece masonry wall composed of “improved high-performance PCM+ with or without GFRP+ different original wall failure modes before reinforcement” was designed. Through diagonal loading shear test, the shear strength, vertical displacement, horizontal relative displacement, and failure models of masonry walls were obtained, and the effects of five different reinforcement methods and different materials on shear strength, stiffness, ductility, and failure modes of masonry walls were studied. The results show that compared with the unreinforced original wall, the shear strength of the masonry wall reinforced with the improved O4PCM is 43.5% higher, and its stiffness is also greatly improved, but the failure mode is still brittle failure; the shear strength of masonry walls strengthened by O4PCM and GFRP is 6.5% higher than that of masonry walls strengthened by O4PCM alone, and the stiffness is also increased. Its failure mode changes from brittle failure to ductile failure; with a failure mode of ductile failure, the shear strength of masonry walls strengthened by P4PCM and GFRP and that strengthened by P6PCM and GFRP are 4.8% and 12.7% higher than that strengthened by O4PCM and GFRP, respectively, and the stiffness is also increased compared with that strengthened by O4PCM and GFRP. After experimental comparison, it is the best scheme to strengthen masonry wall with improved P6PCM and GFRP.

Oxidative stress is always mentioned as a pathologic appearance of Alzheimer's disease (AD). It is attributed to mitochondrial dysfunction closely linked to Aβ deposition and neurofibrillary tangles (NFTs). Octahedral palladium nanoparticles (Pd NPs) exhibited excellent antioxidant enzyme-like activity and outstanding biocompatibility, but the poor blood-brain barrier (BBB) permeability limits their application in the treatment of Alzheimer's disease. Herein, we constructed a borneol (Bor)-modified octahedral palladium (Pd@PEG@Bor) nanozyme platform to eliminate intracellular reactive oxygen species (ROS) and elevate epithelial cell penetrability. Based on in vitro and in vivo studies, we demonstrate that the Pd@PEG@Bor could efficiently reduce ROS and Ca2+ contents, maintain the mitochondrial membrane potential, and further protect the mitochondria in SH-SY5Y cells. Furthermore, the nanozymes could quickly accumulate in the brain of AD mice and alleviate pathological characteristics such as Aβ plaque deposition, neuron loss, and neuroinflammation. The learning ability and memory function of AD mice are also significantly improved. Overall, this work indicates that the Pd@PEG@Bor nanozymes could delay the progression of AD by regulating ROS levels and also provides a new strategy for the treatment of AD.

Sandstone properties can be greatly influenced by water, and many scholars have investigated the interaction between sandstone and water, but paid less attention to the assessment of crack development, fragment features, and damage evolution, which are important factors for evaluation of hydraulic fracturing effect. In this study, uniaxial compression tests were conducted on sandstone specimens in dried, natural, and saturated state, respectively. The generated fragments were collected, and acoustic emission signals were recorded continuously. The grain size distribution and shape description as well as fractal dimension of fragments were all analyzed. Moreover, AE parameter evolution of RA (the ratio of rise time to amplitude) versus AF (average frequency) was obtained and AE damage analysis was carried out. Compared to saturated specimens, dried and natural specimens generated a larger amount of fragments in medium, fine, and micro-grain groups with relatively larger fractal dimension. The average release of cumulative AE energy of dried and natural specimens is much greater than those of saturated specimens. The distributions of RA versus AF imply that water saturation increases tensile fracture whereas decreases shear fracture, which are consistent with the macroscopic failure modes. Compared to saturated and natural specimens, dried specimens which generate more macro-flaws have relatively lower damage correction factor $$\eta$$ and higher damage variable D0. The obtained results can be used as the scientific bases to study sandstone weakening mechanism under water influence.

The poor compatibility of the electrodes-electrolyte interfaces of rechargeable lithium metal batteries (LMBs) with solid-state electrolytes (SSEs) limit their wide applications. Herein, azo compounds as additive are firstly applied in SSEs and we propose a mechanism of regulating the cathode/anode interfaces by azo compounds with different electron groups in SSEs. Through in-situ constructing, the free radicals formed by electron-withdrawing/electron-donating group can be grafted onto different electrodes on demand, thereby forming stable interfaces at both cathode and anode sides, which effectively improves SSEs compatibility in LMBs. Consequently, superior cycling stability is demonstrated by Li/LiFePO4(LFP), Li/LiNi0.5Co0.2Mn0.3O2(NCM523) and Li-S full batteries. The reaction mechanism is confirmed by density functional theory calculations, various electrochemical characterizations, and applying designed azo compounds. This new and universal strategy may pave a way to resolve the bottle-neck interfacial issues of lithium metal batteries by organic compounds.

In 3D IC integration, a critical demand of interfacial joints in high-end devices is ultra-fine pitch, below 2 μm. The pitch cannot be fabricated by using solder joints because of its low melting point. Microelectronic industry prefers a solid state process, but the processing temperature cannot be too high, preferable near 250 °C. Thus, Cu-to-Cu direct bonding has attracted much attention. We have bonded the highly (111)-oriented Cu microbumps to highly (111)-oriented Cu films as well as to randomly-oriented Cu films for comparison, at temperatures from 200 to 350 °C. We examined the microstructures of bonded interfaces and conducted shear tests to evaluate the mechanical strength of the Cu joints. The bonded interfaces for the (111) Cu microbumps to (111) Cu films had fewer voids than those bonded to randomly oriented Cu films. In addition, the bonding strength of the latter is much less than the former. We propose that the fast surface diffusivity on the (111) surfaces play a critical role on surface creep, which increases the bonding strength of the Cu joint. A surface creep model and its creep rate are presented, and a comparison to the experimental data has been made; the agreement is reasonable.

In this paper, the research status of low power micro hot plate gas sensor is reviewed. This type of sensor is characterized by the combination of MEMS technology and related insulation measures. Compared with the traditional ceramic tubular sensor, the power consumption of the sensor is greatly reduced, which provides the possibility of remote sensor arrangement and long term stable operation. This paper firstly collects the current sensor-related heat conduction, heat convection and heat radiation theories, and summarizes the calculation model of heat loss in different regions of the micro hot plate gas sensor. Then, the application examples of the finite element method in the analysis of thermal characteristics of the sensor and the common preparation process of the substrate and gas sensitive layer of the micro hot plate are listed. Finally, the main test methods of the stability and gas sensitivity of the micro hot plate gas sensor are summarized.

Transparent-to-colored electrochromic devices exhibit promising application prospects and have gained popularity. Herein, two triphenylamine derivatives TPA-OCH3 and TPA-CN with styryl moieties and different donor or acceptor units were designed and synthesized to further prepare solvent-resistant thermally cross-linking polymer P(TPA-OCH3) and P(TPA-CN) without any additional initiator. P(TPA-OCH3) and P(TPA-CN) possess two pairs of redox peaks, and P(TPA-OCH3) shows a lower onset oxidation potential compared to P(TPA-CN) because of the pendent donor unit. Correspondingly, both polymers exhibit multicolored changes from the neutral colorless state to noticeable oxidized colors under different potentials. Furthermore, the thermally cross-linking copolymer P(TPA-OCH3-co-TPA-CN) was obtained by TPA-OCH3 and TPA-CN (the molar ratio is 2:1) and presents outstanding electrochromism with four color changes (colorless-orange-blue-purple) due to the multistep redox process of TPA-OCH3 and TPA-CN units. It is more intriguing that the electrochromic device based on the copolymer films possesses a high optical contrast of 57.8% at 680 nm, fast switching time (0.52 and 0.66 s), and robust cyclic stability over 30 000 cycles with very little decay. Therefore, the thermally cross-linking copolymer is a promising candidate material for high-performance transmittive electrochromic devices, such as smart windows, sunglasses, and E-papers.

The surface dynamic and static coefficient of friction of yarns is one of the most important means of characterizing the surface structure of yarns and can provide an important basis for yarn perfo...

Proton-conducting solid oxide electrolysis cells (H-SOECs) have attracted a lot of attention due to their high efficiency, energy-saving ability, and environmental friendliness. The ideal H-SOEC ox...

In this paper, vibration analysis of the 2 D-FG nanoplate is studied based on a novel higher-order shear deformation theory (HSDT). The proposed HSDT is a composition of trigonometric, exponential and polynomial functions which is one of the most accurate HSDTs. The mechanical properties of the nanoplate change along with the length and thickness directions, according to arbitrary functions. To model the displacement field, the impacts of both transverse shear and thickness stretching are considered. To consider the small-scale impact, nonlocal elasticity theory is applied. To obtain the equations of motion, Hamilton’s principle is applied. Navier method is used for a closed-form solution of the 2 D-FG nanoplates with simply-supported boundary conditions. The impact of different parameters including the small-scale parameter are studied on the natural frequency of the system. The results illustrate that when size effect parameter is smaller/greater than 0.5 nm, the impacts of the FG parameters on the frequency of the system increase/reduce.

Discharge failure mechanism of the cable buffer layer is investigated in this paper by the analysis of causes and characteristics of partial discharge (PD) behaviours in the case of failure. The obtained results show that both the volume resistivity and the surface resistance of the buffer layer increase as the relative humidity is elevated. It is found that the electric field distribution inside the buffer layer is distorted when there is poor contact condition and aggravated with the increase of the volume resistivity by the finite element analysis. PD behaviours analysis shows that the PD intensity is closely related to the contact state of the buffer layer, and hence the latter can be reflected by statistical parameters like the maximum pulse amplitude and the average equivalent frequency. The conclusions indicate that the electric field distortion is caused by the variation of the contact state of the buffer layer and the deterioration, which is responsible for the occurrence of PD. Therefore, the PD detection for the suspected faulty cables provides an effective method for the state evaluation of the buffer layer.

A multi-physics simulation model of the tri-post insulator in ±800 kV GIL laid horizontally is established to study the effects of gas convection on surface charges and electric field distribution. Results show that gas density together with the dielectric strength around the upper post is reduced over 11% under gas convection generated by the load current. The larger temperature gradient (29 K) along the lower post accelerates more surface charge injection through insulator buck conduction and distorts the electric field around the bottom of the lower post, which is 19.4% higher than that around the bottom of the upper post. The insulation performance of SF 6 /N 2 filled GIL has the most striking spatial distribution characteristics compared with the insulation performance of SF 6 and C 4 F 7 N/CO 2 . Though the flashover voltage is improved with high gas pressure, the flashover is most likely triggered near the lower post of the insulator according to the stream theory. It is hoped that this study can contribute to a useful guide for the design and manufacture of DC-GIL.

A facile solvothermal method coupled with an annealing strategy is developed to synthesize Fe3O4/carbon (Fe3O4@C) magnetic composite microstructures with different morphologies, including flower-like, hollow spheres and egg-like. The unique multiporous and hollow structure of the as-prepared hierarchical Fe3O4@C hollow microsphere results in an appealing performance as an absorber of Cr(VI) ions in aqueous solution, delivering a high capacity of ~ 197.2 mg/g. Meanwhile, the magnetic Fe3O4 ‘‘core’’ in the hierarchical microstructures can be easily separated from aqueous systems by magnetic separation. Furthermore, the carbon layers effectively prevent the aggregation of magnetic Fe3O4 nanoparticles. The excellent absorbing ability of Cr(VI) ions and easy separation process strongly suggest that the Fe3O4@C magnetic microstructures would have a great potential as adsorbing materials in the large-scale application in environmental purification.

We present a method for atomically precise nanocluster synthesis. As an illustration, we introduced the reducing-ligand induction combined method and synthesized a novel nanocluster, which was determined to be Au28 (SCH2 Ph-t Bu)22 with the same number of gold atoms as existing Au28 (SR)20 nanoclusters but different ligands (hetero-composition-homo-size). Compared with the latter, the former has distinct properties and structures. In particular, a novel kernel evolution pattern is reported, i.e., the quasi-linear growth of Au4 -tetrahedron by sharing one vertex and structural features, including a tritetrahedron kernel with two bridging thiolates and two Au6 (SCH2 Ph-t Bu)6 hexamer chair-like rings on the kernel surface were also first reported, which endow Au28 (SCH2 Ph-t Bu)22 with the best photoluminescence quantum yield among hydrophobic thiolated gold nanoclusters so far, probably due to the enhanced charge transfer from the bi-ring to the kernel via Au-Au bonds.

Graphite carbon nitride (g-C3N4), a two-dimensional polymer semiconductor material, has good semiconductor properties, suitable electronic energy band structure, excellent physical and chemical stability. It is widely used in the field of energy and materials science such as photoelectric conversion. In this paper, the progress of g-C3N4 in dye sensitized solar cells (DSSC) and perovskite solar cells (PSC) was reviewed. As a new semiconductor material, g-C3N4 has the advantages of simple preparation, abundant amino and Lewis basic groups. Therefore, on the basis of excellent structure of g-C3N4, its electronic and optical properties are utilized to further expand its application in the field of photoelectric conversion.

Carbon nitride (CN) polymer is considered as a potential material for photocatalysis, but surfers from the low photoconversion efficiency due to its high defect density. Although the defects can be limited through the crystallization of CN, the photocatalytic activity of single-component photocatalyst is still restricted by the recombination of photoexcited carriers. In our work, the ordered Schottky heterojunction of heptazine-based crystalline carbon nitride (HCN) and Ti3C2 MXene was successfully prepared through ionothermal method. The HCN/Ti3C2 composites exhibit higher photocatalytic performance than pristine HCN. Particularly, the HCNT20 sample exhibits the highest photocatalytic H2 evolution activity, which is about 8 and 2 times higher than that of bulk CN and pristine HCN, respectively. The results of charge transfer dynamics and DFT calculation reveal that the photocatalytic enhancement mechanism is primarily attributed to the synergistic effects of crystallization of CN, excellent conductivity of Ti3C2 and well-constructed Schottky heterojunction.

Fabrics with various patterns and textures can be used to decorate the surface of wood and/or wood composites, enriching indoor environments and reflecting a consumer’s personal taste. To adhere fabric to wood, an environmentally friendly defatted soybean meal (DSF)-based adhesive was modified by adding seven different types of inorganic fillers. The effects of optimal filler composition and concentration on adhesive performance were evaluated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and other techniques. Test results indicated that organokaolin improved the bond properties and usefulness of DSF-based adhesives for decorating wood composites with cotton fabric owing to the even distribution of organokaolin in the adhesive and reinforcement by intercalated filler particles. The cotton fabric bonded to the wood by the optimal DSF-based adhesive had a water resistance that withstood a boiling-water test and maintained a wet peel strength of 0.96 N/mm. However, an excess of organokaolin filler resulted in the formation of loose organokaolin aggregates and reduced crosslinking density of the DSF-based adhesive, which reduced the bond properties. The optimal organokaolin concentration in the DSF-based adhesive was 30 wt%, correlating to a 10.3 % cost reduction compared to an unfilled adhesive.

As an important alloyed element to improve the localized corrosion resistance of stainless steels, Mo has been widely studied by researchers. This article reviews the mechanisms of the effect of Mo on localized corrosion. Two possible effects and corresponding experimental research are described respectively: Mo exists in the passive film as oxide and enhances the film stability (manifesting as lower nucleation probability of localized corrosion and longer delay time of breakdown of the passive film); Mo affects dissolution kinetics and inhibits active dissolution current density (manifesting as smaller metastable pitting current density and size). Then some contradictory results are discussed by considering the pitting model proposedrecently. Strictly speaking, none of the existing experimental results can deny the effect of Mo on the passive film or on the dissolution kinetics. It is reasonable to believe that Mo affects the entire process of localized corrosion rather than a single reaction. Finally, some possible research suggestions are put forward.

Energy transfer and electron transfer are both fundamental mechanisms enabling numerous functional materials and applications. While most materials systems employ either energy transfer or electron transfer, the combined effect of energy and electron transfer processes in a single donor/acceptor system remains largely unexplored. Herein, we demonstrated the energy transfer followed by electron transfer (ETET) process in a molecular dyad TPE-NBD. Due to energy transfer, the fluorescence of TPE-NBD was greatly enhanced in non-polar solvents. In contrast, polar solvents activated subsequent electron transfer and markedly quenched the emission of TPE-NBD. Consequently, ETET endows TPE-NBD with significant polarity sensitivities. We expect that employing ETET could generate many functional materials with unprecedented properties, i.e., for single laser powered multicolor fluorescence imaging and sensing.

The differentiation of human embryonic stem cells (hESCs) into β-cells has potential uses for cell therapy in diabetes. There were massive reported protocols which can be used to generate insulin-producing cells (IPCs) from hESCs, and most of these methods were using recombinant growth factors. However, small molecules can coax ES cells towards pancreatic fate, and could substitute recombinant proteins. To obtain an unbiased characterization, we performed a comparative study with the recombinant protein induction protocol and the small molecule induction protocol and found that the small molecule induction protocol could better inhibit the differentiation of cells into hepatic lineage cells than the recombinant protein induction protocol. On this basis, we further optimized and established an efficient small molecule differentiation system, and the optimized protocol could better inhibit the differentiation of pancreatic exocrine glands. The differentiated hESCs obtained by our optimized protocol comprised approximately 32% IPCs as assayed by flow cytometry analysis. Transmission electron micrograph demonstrated that IPCs obtained in optimized small molecule induction protocol had more and larger secretory granules than those in induction protocol before optimization.

In this paper, a novel modification method of polypropylene (PP) films is proposed in the field of metallized film capacitors for converter valves. An organic crystallization accelerator with good dispersion improves the micromorphology of PP films. The doping content of the organic crystallization accelerator is optimized based on breakdown experiments under DC voltage. The DC breakdown strength is 584.8 kV/mm, an increase of 19.6%, compared with that of the original film. Under DC, DC superimposed harmonics, and DC superimposed pulse voltages, the modified PP film has successfully withstood the tests, showing stable advantages in breakdown properties without increasing the conduction loss. Trap analysis and theoretical modeling were performed to clarify the mechanism of improving electrical performances based on crystallization control. The entanglement layer introduced by the organic crystallization accelerator helps to expand the crystal area, resulting in deep trap sites and limitation of carrier migration. This research can provide a reference for the PP performance optimization for metallized film capacitors of converter valves.

In this paper, we perform a systematical investigation on searching for defect γ -graphyne nanoribbons ( γ -GYNRs) with optimal thermoelectric performance by utilizing nonequilibrium Green’s function combined with Bayesian optimization. The calculations show that Bayesian optimization could quickly and accurately identify the optimal structure with best thermoelectric efficiency. Even in the worst round of optimization, optimal structure could be obtained by only calculating 719 structure candidates (merely 4.35% of all the 16512 candidates). The room temperature thermoelectric figure of merit of optimal defect γ -GYNR (length 11.846 nm, width 1.453 nm) could approach 2.315, which is 5 times of that of pristine γ -GYNR. The obvious advantage of optimal defect γ -GYNR is mainly attributed to the maximum balance of weakening of thermal power factor (side effect) and suppression of thermal conductance (positive effect). Through analyzing the pair correlation function, we also find that the correlations between perfect (defect) unit and perfect (defect) unit are both extremely low for defect γ -GYNRs with high thermoelectric conversion efficiency. The findings presented in this work indicate the effectiveness and superiority of Bayesian optimization in designing defect γ -GYNRs, and could provide new insights for exploring other low-dimensional materials with excellent thermoelectric properties.

A scaled model of the X38-like configuration was simulated under hypersonic conditions for the direct simulation Monte Carlo method and the unified gas kinetic scheme. The inflow conditions considered several flow regimes, from the near-continuum through the slip-transitional to the free molecular regime. Flow fields and surface properties were compared in detail between these two methods. Not only the density and temperature contours distribution but also the surface pressure, heat flux, friction distribution, both kinetic methods give fairly consistent results. Aerodynamics of the model were also achieved and compared. The results provided by both methods agreed with each other very well. The effects of the Knudsen number and angle of attack were assessed. It is meaningful to carry out comparative studies and accelerate both methods to further progress.

The recent development of 2D lamellar membranes may lead to the next generation of membrane processes for molecular separation, but smart regulation of substance permeability has rarely been report...

A thermal-responsive photonic crystal material was fabricated by forming an inverse opal nanocomposite hydrogel of poly(N-isopropylacrylamide) (IONHPNIPAm) within the interstitial space of a polystyrene photonic crystal template. In IONHPNIPAm, PNIPAm were physically cross-linked with two kinds of nanoparticles (carbon dots and laponite clays). The integration of carbon dots and laponite clays for physical crosslinking endowed IONHPNIPAm sufficient strength and self-healing property. IONHPNIPAm films can be completely peeled from the substrates to be utilized as an independent photonic crystal material. The structural color and optical diffraction of the IONHPNIPAm exhibits a rapid reversible change in response to external thermal stimuli due to its physical cross-linking feature. Moreover, the IONHPNIPAm shows clear fluorescence due to the introduction of carbon dots, which enables a convenient way for chemical detection (such as the detection of silver ions). This stimuli-responsive photonic crystal materials based on physically cross-linked inverse opal nanocomposite hydrogels with fast response and good mechanical stability are promising for applications in the fields of smart optical detectors, thermal-responsive sensors and chemical detectors.

A huge challenge is to control the nucleation of crystallites/aggregates in the solution during polymer film formation to generate desired structures. In this work, we investigate crystallization of P(NDI2OD-T2), a donor-acceptor polymer semiconductor, with controlled solution flow along the contact line between the drying film and solution through a seesaw-like pivoting of samples during polymer drying. By controlling the pivoting frequency/amplitude, various types of line patterns can be observed: (I) an array of fishbone-like stripes oriented in the film-growth direction; (II) the pinning-depinning of contact line (PDCL)-mechanism-defined patterned wires along the contact line; and (III) periodic twined crystalline line pattern oriented in the direction of the contact line. The rich variety of pattern formation observed is attributed to the distinctiveness of the donor-acceptor conjugated polymer structure. The result measured from thin-film transistors made of the generated films/structures showed that the charge mobility of P(NDI2OD-T2) does not change much with the film morphology, which supports recent controversy over the charge-transportation mechanism of some donor-acceptor polymer semiconductors.

Wearable biosensors are considered to be a promising technology that revolutionizes conventional health monitoring methods as it is able to provide precautions when potential health problem is detected. However, the current fatigue-monitoring methods are still using either invasive blood tests or bulky inconvenient devices. Herein, we present a new skin patch sensor based on porous Ultra-High-Molecular-Weight Polyethylene (UHMWPE) nanomembranes which tracks muscle fatigue through sweat biomarkers, particularly cortisol hormone. By having nano-level thickness (i.e. around 100nm), the sweat sensor is able to conform perfectly to human skin without the necessity of any adhesives. We used Raman spectroscopy to analyze the sweat cortisol in the skin patch, established the calibration curve for both qualitative and quantitative characterization of sweat cortisol level change and validated the measurements with the blood samples collected at the same exercise intensity. From our experimental data, it is concluded that the cortisol level increases as the exercise intensity are increased and a strong correlation between the sweat cortisol and blood cortisol has been proven, demonstrating the patch’s ability to detect sweat cortisol which acts as a strong indicator of sports fatigue level. Our developed UHMWPE membrane opens up a large opportunity for developing a one-of-a-kind sweat sensor by further integrating it with flexible electronics for signal processing and real-time transmission in future work.

Although π-conjugated two dimensional (2D) covalent organic frameworks (COFs) have been extensively reported, developing fully π-conjugated 3D COFs is still an extremely difficult problem due to the lack of fully π-conjugated 3D linkers. We synthesize a fully conjugated 3D COF (BUCT-COF-1) by designing a saddle-shaped building block of aldehyde-substituted cyclooctatetrathiophene (COThP)-CHO. As a consequence of the fully conjugated 3D network, BUCT-COF-1 demonstrates ultrahigh Hall electron mobility up to ≈3.0 cm2 V-1 s-1 at room temperature, which is one order of magnitude higher than the current π-conjugated 2D COFs. Temperature-dependent conductivity measurements reveal that the charge carriers in BUCT- COF-1 exhibit the band-like transport mechanism, which is entirely different from the hopping transport phenomena observed in common organic materials. The findings indicate that fully conjugated 3D COFs can achieve electron delocalization and charge-transport pathways within the whole 3D skeleton, which may open up a new frontier in the design of organic semiconducting materials.

Removing or adding kernel atoms of metal nanoclusters (NCs) without leaving a trace is a substantial challenge because the kernel atoms are inside and covered by the outer staples. However, such kernel tuning is very important for improving the properties and acquiring an in-depth understanding of the kernel-property correlation. Photoluminescence (PL) is one of the most intriguing characteristics of metal NCs but has not been well understood until now. Inspired by these challenges/questions, we conducted this study and, for the first time, achieved the traceless removal of two kernel atoms in a gold nanocluster by applying a simple thermal treatment and revealed its impact on PL. Further, we demonstrated that the kernel Au-Au bond length can be an indicator for a comparison of the PL or kernel charge state between nanoclusters with similar kernel structures and sizes.

Immune checkpoint blockade (ICB) has been regarded as one promising approach for tumor immunotherapy. Here, we report a functional nanoplatform based on generation 5 (G5) poly(amidoamine) (PAMAM) dendrimer-entrapped gold nanoparticles (Au DENPs) as a nonviral vector to deliver programmed death-ligand 1 (PD-L1) small interfering RNA (siPD-L1) for subsequent PD-L1 gene silencing-mediated tumor immunotherapy. In this work, G5 dendrimers with amine termini were partially decorated with methoxy polyethylene glycol ( m PEG) on their periphery, entrapped Au NPs within their interiors, and were eventually labeled with fluorescamine. The generated functional Au DENPs possess desired dispersibility in water and colloidal stability, satisfactory cytocompatibility after complexation with siPD-L1, and efficient gene delivery performance. Strikingly, the functional Au DENPs enabled the delivery of siPD-L1 to cancer cells to efficiently knock down the PD-L1 protein expression, thus boosting the ICB-based immunotherapy of a xenografted melanoma mouse tumor model with a tumor inhibition efficiency much higher than the PD-L1 antibody. The immune responses were also well demonstrated by downregulation of PD-L1 protein on the tumor cell surface and abundant distribution of CD8+ and CD4+ T cells in the infiltrating tumor tissue and spleen organ. The developed functional dendrimer-based nanoplatform may be promising to boost ICB-based immunotherapy of other tumor types.

As low-cost electrocatalysts for oxygen reduction reaction applied to fuel cells and metal-air batteries, atomic-dispersed transition metal-nitrogen-carbon materials are emerging, but the genuine mechanism thereof is still arguable. Herein, by rational design and synthesis of dual-metal atomically dispersed Fe,Mn/N-C catalyst as model object, we unravel that the O2 reduction preferentially takes place on FeIII in the FeN4 /C system with intermediate spin state which possesses one eg electron (t2g4eg1) readily penetrating the antibonding π-orbital of oxygen. Both magnetic measurements and theoretical calculation reveal that the adjacent atomically dispersed Mn-N moieties can effectively activate the FeIII sites by both spin-state transition and electronic modulation, rendering the excellent ORR performances of Fe,Mn/N-C in both alkaline and acidic media (halfwave positionals are 0.928 V in 0.1 M KOH, and 0.804 V in 0.1 M HClO4), and good durability, which outperforms and has almost the same activity of commercial Pt/C, respectively. In addition, it presents a superior power density of 160.8 mW cm−2 and long-term durability in reversible zinc–air batteries. The work brings new insight into the oxygen reduction reaction process on the metal-nitrogen-carbon active sites, undoubtedly leading the exploration towards high effective low-cost non-precious catalysts., The working mechanism of several low-cost electrocatalyst materials is still arguable. Here the authors show a model Fe,Mn/N-C catalyst where the oxygen reduction preferentially takes place on Fe(III) sites with the intermediate spin state (t2g4 eg1) caused by the adjacent Mn-N moieties.