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Higher cutting speed is always the pursuit of industries as it is one of the most effective methods to improve machining efficiency, which requires a better understanding of deformation and microstructure evolution process during chip formation. In this study, chip formation process is divided into three different sections of pre-loading, loading and unloading to analyze the mechanisms of microstructure evolution sequentially through a coupled finite element and cellular automata approach. The non-uniform distributed fields of strains, strain rates and temperatures induced by different stage during chip formation process are obtained and then transferred as boundary conditions for microstructure evolution. In pre-loading condition, microstructure evolution appears only along shear band with small sizes, which provides more boundaries for activation of DRX mechanisms in following conditions. Final microstructures always show a gradient distribution along shear direction, and secondary shear zone makes the greatest contribution to grain refinement. Average grain sizes and microstructure distribution have shown a good agreement between experimental data and simulation results, which indicates that this sequential simulation approach can perform a better description of those process characteristics of microstructure evolution during a continuous process with complicated boundary conditions.

In this study, we developed a micromechanics scheme to predict the upper and lower bounds on the creep strain and stress relaxation induced by interface diffusion in metal-matrix particulate composites. The normal stress acting on the matrix-inclusion interface, which is the driving force for interface diffusion, is estimated by using the Hashin-Shtrikman bounds and mean-field micromechanics theory. Analytical solutions of upper and lower bounds on the creep strain under constant stress and the relaxed stress at fixed strain are obtained. Results of this work show that the ultimate creep strain and relaxed stress are only related to the material properties and the percentage of each component, such as volume fraction of inclusion and elastic modulus ratio of inclusion to matrix. The parameters of interface diffusion only influence the rate of creep strain. It is found that the creep deformation and stress relaxation of composites are more sensitive to the volume fraction of inclusion than the elastic modulus ratio. The methodology of this study also applies to analysis of creep deformation of composites where both the matrix creep and interface diffusional creep need to be considered. The present study offers new perspectives for in-depth understanding of creep behavior of composites driven by mass diffusion along inclusion-matrix interface.

Highly ordered silicon nanostructures were fabricated using the nanosphere mask and reactive ion etching method. A self-assembled SiO2 nanospheres monolayer obtained by spin-coating method was used...

Asymmetric macromolecular double-brushes (MDBs) are composed of two different side chains grafted on a linear backbone, possessing distinct assembly behaviors in comparison with conventional amphiphiles, owing to the Janus architecture and combined effects of backbone and hetero double-brushes. Additionally, the introduction of unique functionalities and responsiveness into the self-assembly system of MDBs endows extra opportunities to pursue morphologic diversity and intriguing properties. Herein, we report the synthesis of Janus-like MDBs of polyacrylate

The fabrication of silicon hierarchical structures with both superior light trapping and efficient carrier collection is significant for improving the efficiency of c-Si solar cells. Here, we present a simple method to fabricate a novel hierarchical structure composed of inverted pyramid (IP) with different sizes by varying nanostructure rebuilding (NSR) ratio ([NaF]:[H2O2]) during NSR treatment of silicon nanostructures containing Ag nanoparticles (AgNPs), followed by a systematic investigation of the underlying mechanism behind the structure formation. The silicon nanostructure is obtained through a well-known Ag assisted chemical etching method. Independent of NSR ratio, large-size IP with AgNPs fixed at the vertex can always form by carefully modulating NSR duration. Interestingly, by changing NSR ratio to 1:2, 1:4 and 1:6, it is found that the dissolution rate of AgNPs at the vertex during NSR process rises accompanied with increasing the number of etching points by AgNPs redeposition on the IP side walls, forming hierarchical structures composed of IP with different sizes. Moreover, the weakening of masking effect of AgNPs is demonstrated with the increase of AgNPs dissolution, rendering the IP vertex from flat to sharp. By adopting the best hierarchical structure for light trapping, the corresponding Al back surface field (Al-BSF) c-Si cell can reach a high efficiency of 19.80% with a Voc of 644 mV, Jsc of 38.77 mA/cm2, FF of 79.32%, which is 0.20% and 0.27% absolute higher than that of conventional random IP and micro pyramid (MP) based cell, respectively.

SiC–TiB2 ceramic nanocomposites are valuable ultra-high temperature materials, which are rarely prepared from preceramic polymers. In this work, we synthesized SiC–TiB2 nanocomposites from a new preceramic polymer called titanium- and boron-modified polycarbosilane (TB–PCS). The polymer structure was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The structure, composition, and morphology of the resulting ceramic products were investigated by FT-IR, X-ray diffraction, and transmission electron microscopy. The elements of titanium and boron were incorporated into the preceramic polymer, and nanoscale TiB2 and β-SiC grains generated in situ were detected in the pyrolyzed ceramic products at temperatures higher than 1400 °C. The new preceramic polymer presents a novel approach to preparing SiC–TiB2 nanocomposites.

Porous silicon monoxide (p-SiO) is one of the most promising anode materials for lithium-ion batteries because it possesses high theoretical capacity and small volume expansion. Traditionally, SiO is prepared at 1200 °C, which restrains the application of SiO materials due to its high consumption of energy. Herein, a low-temperature synthesis process of p-SiO at 650 °C is developed from a controllable magnesiothermic reduction of porous silica. Compared with normally reduced solid silica (SiO2@SiO), p-SiO is fabricated more easily from porous SiO2 due to the improved contact between SiO2 and Mg atom. Moreover, high porosity of p-SiO facilitates the growth of carbon shell, making p-SiO@C with remarkable electrochemical properties. The reversible capacity for p-SiO@C (839.6 mA h g−1, at 500 mA g−1) is about two times that for SiO2@SiO@C (426.4 mA h g−1, at 500 mA g−1) after 110 cycles, and the synergetic properties of p-SiO@C further presents good cycling stability (777.1 mA h g−1, at 500 mA g−1 after 300 cycles) and excellent rate capability (977 mA h g−1, at 1000 mA g−1). The low-temperature fabrication of p-SiO followed by carbonization is promoting for practical application in high-performance Si-based lithium-ion battery.

Photo-induced self-healing materials, which can be controlled remotely, instantly and precisely, are attracting increasing attention in various fields. However, it still remains challenging to modulate the self-healing materials with integrated functionalities possessing multiple-wavelength photo-responsiveness. Herein, we report a strategy of building a photo-responsive self-healing system capable of performing ultraviolet (UV) and near-infrared (NIR) two-wavelength induced double-repair. The strategy is based on azobenzene-functionalized multiwalled carbon nanotubes (MWCNTs) via a two-step method. Oxidized MWCNTs were first reacted subsequently with thionyl chloride, glycol, and 2-bromoisobutyryl bromide to yield MWCNT-Br macroinitiators. Then atom transfer radical polymerization (ATRP) of azobenzene monomer, 6-(4-butyl-4′-oxyazobenzene) hexyl methacrylate (Azo), was directly initiated by MWCNT-Br, affording MWCNT-PAzo nanocomposites. The MWCNT-PAzo system can undergo photothermal- and photochemical-induced solid-liquid phase transition to manipulate the self-healing behavior while MWCNTs act as photo-absorbers/heat sources and azobenzene moieties serve on glass transition temperatures (Tg) switchers, in response to NIR and UV light stimuli, respectively. To our best of knowledge, this is the first-time that MWCNT-PAzo nanocomposites possess two-wavelength photo-responsiveness and exhibit excellent self-healing performance through the irradiation of two-wavelength bands (365 and 808 nm) of UV/NIR light.

Among large numbers of transition metal dichalcogenides (TMDCs), monolayer rhenium disulfide (ReS2) is of particular interest due to its unique structural anisotropy, which opens up unprecedented opportunities in dichroic atomical electronics. Understanding the domain structure and controlling the anisotropic evolution of ReS2 during the growth is considered critical for increasing the domain size toward a large-scale growth of monolayer ReS2. Herein, by employing angle-resolved Raman spectroscopy, we reveal that the hexagonal ReS2 domain is constructed by six well-defined subdomains with each b-axis parallel to the diagonal of the hexagon. By further combining the first-principles calculations and the transmission electron microscopy (TEM) characterization, a dislocation-involved anisotropic evolution is proposed to explain the formation of the domain structures and understand the limitation of the domain size. Based on these findings, growth rates of different crystal planes are well controlled to enlarge the domain size, and moreover, single-crystal domains with a triangle shape are obtained. With the improved domain size, large-scale uniform, strictly monolayer ReS2 films are grown further. Scalable field-effect transistor (FET) arrays are constructed, which show good electrical performances comparable or even superior to that of the single domains reported at room temperature. This work not only sheds light on comprehending the novel growth mechanism of ReS2 but also offers a robust and controllable strategy for the synthesis of large-area and high-quality two-dimensional materials with low structural symmetry.

Antifouling surfaces with optimized conformation and compositional heterogeneities are presented with the goal of improving the efficacy of surface protection. The approach exploits the adhesive group (thiol or catechol chain end) to anchor asymmetric polymer brushes (APBs) bearing amphiphilic side chains with synergistic nonfouling and fouling-release abilities onto the surface. The conformation of the APB surface is close to the fencelike structure, which mimics lubricating protein lubricin, endowing the surface with capacity of enhanced protection and antiadhesivity, even facing the high compression of fouling. By utilizing a poly(Br-acrylate-alkyne) macroagent comprising alkynyl and 2-bromopropionate groups, we prepared a series of APB surfaces based on polyacrylate-g-poly(ethylene oxide)/poly(pentafluorophenyl methacrylate) (PA-g-PEO/PPFMA) APBs to explore the influence of the content of the fluorinated segment and bioinspired topological polymer chemistry on their antifouling performance. The APB surfaces can not only provide compositional heterogeneities of PEO and fluorinated segments in each side chain but also give a high surface coverage because of the characteristic of high grafting density of macromolecular brushes. It was found for the first time, as far as we are aware, the fencelike APB surface shows excellent antifouling performance with less protein adsorption (up to 91% off) and cell adhesion (up to 84% off) in comparison with the controlled substrate under relatively long incubation time.

Magnesium batteries based on Mg2+/Li+ dual ion electrolytes (MLIBs) have attracted increasing attention due to fast Li+ or Mg2+/Li+ insertion kinetics, abundant Mg resources, and high volumetric capacity of dendrite-free Mg anodes. Herein, we report polyaniline (PANI)–coated VS4@reduced graphene oxide (rGO) with nanostructures synthesized via hydrothermal synthesis and subsequent PANI polymerization as the cathode material for MLIBs. The PANI layer serves as a conductive medium to enhance electron transfer and Mg2+/Li+ transportation as well as to mitigate the structure changes of VS4 during the cycling process. Indeed, this material demonstrates enhanced electrochemical performance with a high discharge capacity of 200.7 mAh g−1 after 20 cycles and 91.2% retention after 50 cycles. Mechanism analysis reveals that Li+ insertion into VS4 produced an amorphous VS4 host in the first discharge, which inclined to store Mg2+ rather than Li+ in the subsequent cycles. Our study provides new insights into the development of amorphous electrode materials for magnesium batteries.

Preparation of well-ordered TiO2 films from alkaline solution by liquid phase deposition (LPD) method is still challenging owing to the fact that, in traditional mixing process, several disadvantages exist in controllable homogenous chemical reactions. In this contribution, mixing process in a porous dispersed double T-junction micromixer was designed and investigated using numerical simulation. It is obtained that high mixing intensity can be achieved by micromixer with inlet velocity of 0.6 m s−1 and microfiltration meshes 10 μm in size. A micromixing-assisted platform consisted of two syringe pumps and a micromixer was manufactured to efficiently fabricate TiO2 films via mixing of (NH4)2TiF6 and CO(NH2)2 as reactants and fluorine doped tin oxide, F: SnO2 (FTO), conducting glass substrates by LPD in alkaline solutions. The results suggest that surface morphology of TiO2 films fabricated by micromixing can be easily controlled in comparison with that of specimens prepared by traditional stirring mixing process. The dense and well-ordered TiO2 films derived from micromixing have enhanced adhesion strength, high hardness, good hydrophilic and excellent photoelectrochemical properties. Particularly, homogeneous reaction could be inhibited in micromixer and an ideal supersaturation solution would be formed via micromixing treatment, which significantly facilitates the formation of high quality TiO2 films by heterogeneous nucleation on substrate surface. These obtained achievements are expected to promote further application of TiO2 films in a variety of domains including photocatalysis and corrosion protection of metals.

Overcoming slow kinetics of cathodic electrochemical reactions is a key factor toward achieving economical and efficient electrocatalysts for practical application of primary Al-air batteries. In this study, a hybrid catalyst with specific surface area and manganese valence controlled α-MnO2 nanotube decorated by silver nanoparticles (Ag/MnO2-3) is successful synthesized. A facile hydrothermal method was used, followed by liquid phase reducing treatment. The Ag/MnO2-3 showed not only superior catalytic activity for the oxygen reduction reaction with more positive onset potential (0.996 V vs. RHE) and comparable half-wave potential (0.870 V vs. RHE) to the commercial Pt/C catalyst but also a higher discharge voltage plateau (∼1.1 V at discharge current density of 50 mA cm−2) with superior stability in the primary Al−air battery test. The high electrocatalytic activity of the Ag/MnO2-3 nanohybrid is attributed to the larger specific surface area of MnO2 nanotubes and its ultrahigh atomic ratios of Mn3+/Mn4+ on the surface. This results in a strong synergistic effect between manganese dioxide nanotube and Ag nanoparticles to inhibit the accumulation of hydrogen peroxide. This material is promising for applications in Al-air batteries.

To develop high-performance and efficient bifunctional electrocatalysts for Li O2 batteries, a promising new material is developed in this study, which consists of hierarchical porous hollow carbon nanofibers (HCNFs) with Ag/Co@CoO nanoparticles immobilized inside. This material is prepared using a facile and convenient coaxial electrospinning method, followed by a simple heat treatment. The Ag/Co@CoO HCNF cathode shows low polarization and excellent cycle performance. A combination of structural characterizations (e.g., scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman scattering spectroscopy, and the Brunauer-Emmett-Teller method) and electrochemical analyses shows that the excellent battery performance of the Ag/Co@CoO HCNF cathode can be attributed to its hierarchical porous structure, high surface area and high content of active sites combined with the synergetic interactions between Ag and Co@CoO as well as the improved electrical conductivity. Notably, the introduction of Ag may promote the Li2O2 to grow and crystallize into nanosheets due to the synergetic interactions between Ag and CoO. The petal-like Li2O2 discharge products formed on the Ag/Co@CoO HCNF cathode are more readily decomposed than the film-like Li2O2. Our findings provide a reference for designing free-standing high-performance hollow-structured Ag/Co@CoO hybrid electrodes by coaxial electrospinning for non-aqueous Li O2 batteries.

In this study, we present a new micromechanics method to predict the transverse creep rate induced by interface diffusion in unidirectional fiber-reinforced composites and evolution of overall creep strain under constant applied stress. An analytical solution for creep rate induced by interfacial diffusion, depending on the applied stress, fiber volume fraction and radius of the fiber, as well as the modulus ratio between the fiber and the matrix, is obtained. A micromechanics model is proposed to estimate the stress field in the fiber, which is related to the driving force for the interface diffusion, the normal stress on the interface. Comparison with finite element analysis shows that the present micromechanics model is of good accuracy, especially for high fiber volume fraction and large elastic modulus ratio between fiber and matrix. With the proposed micromechanics method based on the average field theory, the variation of overall creep strains and stresses with time in fibers under constant external load are analyzed by the incremental creep analysis procedures.

Rechargeable aluminum-ion batteries are considered promising candidates for the new generation of energy storage systems because of their high capacity, low cost, and high security. The most urgent...

Lithium metal is one of the most exceptional anode materials for the next-generation rechargeable batteries because of its ultrahigh theoretical specific capacity and lowest reduction potential. Unfortunately, low Coulombic efficiency, poor cycling lifespan and short-circuiting-related safety issues due to the uncontrolled growth of lithium dendrites during battery cycling have hindered practical applications of rechargeable lithium-metal batteries. Herein, we report an efficient strategy to overcome these shortcomings by using a multi-walled carbon nanotube interlayer film with controllable thickness between lithium anode and a separator. Lithium electrodes with added interlayers can stabilize the cycling of symmetrical cells up to 600 h at 3 mA h cm−2 capacity and 5 mA cm−2 current density and up to 180 h at 5 mA h cm−2 capacity and 10 mA cm−2 current density, respectively, without any signs of short circuits. The volume expansion is significantly mitigated by the interlayer during cycling. Using lithium anode with interlayer, we achieve excellent Coulombic efficiency, superior capacity retention and small polarization for lithium-oxygen battery and lithium-lithium cobalt oxide/lithium iron phosphate batteries. These interlayers, produced using low-cost raw materials and simple methods, have a promising potential for realization of high-capacity, dendrite-free and long-life lithium metal anodes for the large-scale production.

In this work, a novel alternating amphiphilic copolymer (AAC) P(EG4-a-NAzoOMe) with azobenzene pendants was synthesized through the azide–alkyne click reaction. This proposed AAC exhibits unusual photo- and pH-responsive behaviors by taking advantage of a special alternating amphiphilic topology to prevent the azobenzene pendants from ordered aggregation. P(EG4-a-NAzoOMe) could self-assemble into different sized homogeneous large compound micelles (LCMs) by tuning the initial concentration. The LCMs responded to UV stimuli almost as fast as the P(EG4-a-NAzoOMe) polymer, and the size of LCMs enlarged with the acidity of the solution together with the color change from yellow to violet. Moreover, the LCMs featured acidity-enhanced aggregation induced emission (AIE) similarly because of the special alternating amphiphilic topology. The first reported stimuli-responsive AAC could not only serve as a promising tunable delivery carrier or sensor, but also be inspirational for developing azobenzene AIE materials.

Surface integrity is the permanent pursuit of industries for decades, and microstructure is a key factor controlling physical and mechanical properties of machined surfaces. During machining, a complicated non-uniform distribution of deformation fields will be applied to machined surfaces, as a result, microstructure evolution will be significantly influenced. In this study, a coupled finite element (FE) and cellular automata (CA) approach is used to characterize and predict microstructure evolution during high-speed machining oxygen-free high-conductivity (OFHC) copper, where a unique material model is presented to describe both constitutive behaviors and microstructure evolution, and a mixed mechanism of continuous dynamic recrystallization (cDRX) and discontinuous dynamic recrystallization (dDRX) is adopted to show grain refinement and grain growth procedure under gradient distributed fields of strains, strain rates and temperatures in machined surfaces. A similar gradient distribution of grain sizes is obtained through both simulation and experimental results, which validates the predictive model and presents an in-depth understanding of microstructure evolution process during surface formation, and it shows the primary factors influencing the grain size distribution in sub-surface are cDRX-induced grain refinement and dDRX-induced grain growth. Moreover, the gradient distribution of microstructures in refined sub-surfaces could be used to explain mechanisms of sub-surface damage in the future.

Soft robot has become a hot topic recently due to its distinct advantages over traditional rigid robots such as high deformability and good impact resistance. However, the coupled deflections of flexile materials bring challenges to soft robotic research in many aspects such as kinematic modeling, dynamic analysis, and control. Besides, unwanted deformations might enlarge external dimensions of soft robots, causing a reduction in the efficiency and bringing about unexpected or harmful contacts with surrounding environments that will significantly affect the robots' performance. In this study, we propose a new inflatable soft actuator driven by two spiral chambers twined with fibers for the first time. A key feature of this actuator is that it possesses a pure and high-efficient torsional motion with no bending and extension movements when works without load, which reduces the difficulties of theoretical analysis and control to some extent. Kinematic model is established by combining virtual work principle and elastic strain energy function for nonlinear flexible materials. The new soft torsional actuator module is carefully designed and fabricated, of which both the kinematic property and output torque are investigated experimentally. Results show that the module exhibits good linearity with air pressure ranging from 35 to 100 kPa, and can provide a torsion angle of up to 110° with an angular displacement accuracy of ±2° in empty loaded conditions; the maximum output torque reaches 0.026 N·m with the corresponding air pressure of 100 kPa. Finally, three soft robots are assembled by utilizing this new, inflatable, pure, soft torsional actuator, and successfully carry out different manipulating tasks. This work might provide some insights into the design of linear soft actuators without coupled deformations in future.

Carbon nanotube/Boron nitride(CNT/BN) nanocomposites were performed by a facile method with boric acid (H3BO3) and melamine (C3H6N6). Uniform boron nitride (BN) precursor deposition films were deposited onto the surface of multiwall carbon nanotubes (MWCNTs),which involves attachment of the precursor and subsequent nitridation in ammonia atmosphere at 1050 °C. The qualitative and quantitative analysis of X-ray diffraction (XRD) on the crystal structure and phase composition. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize the material surface morphology and coating structure. Chemical composition analysis of surface and chemical bonds formed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared Spectroscopy (FTIR) confirmed as well as the oxidation resistance under high temperature by thermal gravimetric analysis and differential thermal analysis (TG-DTA). The results indicate that the boron nitride coating on carbon nanotubes composite has been synthesized successfully by this method and greatly improves the antioxidant performance of carbon nanotubes compared with the original carbon nanotubes (690 °C, compared to 550 °C of original carbon nanotubes), which provides a potential application at high temperatures for carbon nanotube materials.

Given their rapid development, aerospace and other high-tech industries are in urgent need of process technology for large complex thin-walled shells represented by large thin-walled parts with ring inner ribs and curvilinear generatrix. To make up for the deficiency in existing forming methods, this paper presents a compound spinning process that integrates counter-roller spinning, multi-neck spinning, and hot spinning. The finite element models for the counter-roller spinning and multi-neck spinning forming of such parts are established, and these models can simulate the influences of different spinning process parameters on workpiece maximum equivalent stress and maximum ovality. The 2A12 aluminum alloy tube blank is used in this paper. The process parameters for obtaining the counter-roller spinning for such parts are as follows: a feed ratio of 1.0 mm/r and a roller nose radius of 8 mm. The process parameters of multi-neck spinning are as follows: a feed ratio of 3.0 mm/r and a roller nose radius of 80 mm; and the forming temperature of hot spinning is 200–250 °C. Verification by a compound spinning test found that the numerical simulation results are consistent with the process test results. The process parameters can be used for guiding the actual production of large thin-walled parts with ring inner ribs and curvilinear generatrix.

A novel approach for preparing self-cleaning anti-fouling surfaces with compositional heterogeneous polymer brushes at a molecular-length scale was developed. This approach exploits three critical elements including hydrophilic poly(ethylene glycol) (PEG) brushes with non-fouling functionalities, self-cleaning fouling-release hydrophobic poly(2,2,3,3,3-pentafluoropropyl acrylate) (PPFA) brushes and catechol moieties, an important component of mussel adhesive proteins (MAPs), to anchor asymmetric polymer brushes onto surfaces. Well-defined PtBBPMA-co-PPEGMEMA-co-PDOMA macroinitiators were first prepared by RAFT copolymerization of tert-butyl 2-((2-bromopropanoyloxy)methyl)acrylate (tBBPMA) bearing a Br-containing ATRP initiating group, poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) macromonomer and N-(3,4-dihydroxy-phenethyl) methacrylamide (DOMA) with an adhesive anchoring group of catechol moieties. The target asymmetric polymer brushes were obtained by ATRP of PFA initiated by the macroinitiator via the grafting-from strategy. By using the drop coating method, the asymmetric polymer brush surface could form a layer of amphiphilic brushes onto the substrate with the assistance of adhesive anchoring groups. With a dense heterogeneous brush conformation at a molecular-length scale, (PtBA-co-PPEGMEMA-co-PDOMA)-g-PPFA-based surface shows considerable self-cleaning anti-fouling performance with less protein adsorption (up to 93% off) and cell adhesion (up to 88% off) compared to the bare surface.

The application of anodic bonding with metal or alloy films as the intermediate layer in micro electromechanical systems (MEMS) is becoming more widespread. Simultaneously, the realization of lower bonding voltage and current is an urgent problem to be solved in anodic bonding, cause large voltages and currents can cause damage and failure to tiny devices of MEMS. Sputtering aluminum as an intermediate layer, well-bonded silicon to glass wafers can be obtained with lower bonding current by applying triboelectric nanogenerator (TENG) instead of traditional direct-current (DC) power supply for the first time. Meanwhile, the tensile strength of the bonded wafers with an intermediate aluminum layer is up to 20 MPa, which is comparable with the DC driven bonded strength and is also 50 % higher than that without the aluminum layer. The TENG-based anodic bonding of silicon to glass with an aluminum layer has good bonding quality, which exhibits potential usefulness for application in MEMS packing.

Micro and nano light-trapping structures are widely applied to improve the performance of optoelectronic devices. In this work, inverted-pyramid light trapping texture on industrial-sized p-type silicon was prepared by a rapid and repeatable one-step room-temperature Cu-MACE process. On this basis, various TMOs (transition metal oxide)-Si heterojunction photodetectors (PDs) are fabricated by a low-temperature process. After careful comparison, a ZnO/Al2O3/p-Si/Al2O3/CuO heterojunction is selected as the ideal device structure, and the corresponding work mechanism is proposed. Finally, by optimizing the Al2O3 tunneling layers’ thickness, a high-performance NIR PD working at 980 nm and −5 V bias stands out. The bifacial carrier selective transportation PD exhibits a considerable detectivity (5.56 × 1011 Jones) and a high responsivity (7.10 A/W). Our work will expand the application of inverted-pyramid textured silicon and will pave a road for mass fabrication of TMOs-Si heterojunction PD.

BN-coated FeNi nanoparticles (i.e., FeNi/BN) has been prepared via liquid phase reduction process followed by high temperature calcination. TEM and SEM images confirm the nano-dimensional structure with core/shell structure, with FeNi NPs as core and BN layers as shell. The anti-oxidation performance of the coated and uncoated powders were investigated from room temperature to 900 °C by TGA and DTA, thermal analysis data revealed that the FeNi NPs are oxidized at 220 °C in the air, while the FeNi/BN samples are stable below 570 °C. This results from the fact that the enhancement of the thermal stability by the BN shell. In addition, the BN layers limit the growth of FeNi NPs, resulting in the lower saturation magnetization and higher coercivity, compared with pure FeNi NPs.

The physical and morphological properties of particles and interfaces can seriously impact the whole mechanical behavior of particle-reinforced composites. In this work, we devise a robust coupling model of the discrete element method (DEM) and the finite element method (FEM) to numerically investigate the effective elastic moduli of particle-reinforced composites consisting of elliptical particles of high packing density, compliant interfaces and homogeneous matrix. In the numerical model, a novel parametric equation for the topological geometry of an interface that is treated as an interphase model is formulated to realize a compliant (penetrable) layer with a constant finite thickness coated surrounding each elliptical particle. Additionally, a convenient strategy is implemented to cope with periodic boundary conditions containing numerous particles. On the other hand, we also propose a micromechanical theoretical framework to derive the effective elastic properties of such three-phase composites by incorporating the fraction of compliant interfaces that is theoretically computed by using the statistical geometry of composites. It is shown that our numerical and theoretical models lead to the prediction of elastic moduli of particle-reinforced composites with nonspherical particles of high packing density to a reasonable accuracy by comparing with available experimental data. Moreover, utilizing the proposed models, we systematically investigate the influence of the characteristics of particles and interphase such as the high packing density and geometries of elliptical particles, and interphase fraction, thickness and stiffness on the elastic moduli of particle-reinforced composites. We find that these physical characteristics play significant roles in determining the mechanical behavior of composites, suggesting that the properties of such materials can be tailored via proper composites engineering and design.

Novel single-source-precursors (SSPs), namely carbon nanotube modified poly (methylvinyl) silazane (CNTs-HTT 1800), were synthesized via amidation reaction of poly (methylvinyl) silazane (HTT 1800) with carboxylic acid functionalized carbon nanotubes (CNTs-COOH) at the assistance of ZnCl2 catalyst, which was confirmed by means of Fourier transform infrared spectra (FT IR) and transmission electron microscopy (TEM). Besides, the TEM results unambiguously show the homogeneous distribution of the CNTs in the matrix of SSPs while serious aggregation of the CNTs in the matrix of physically-blended-precursor. Crack-free monolithic silicon carbonitride modified by carbon nanotubes ceramic nanocomposites (CNTs-SiCN) were prepared through pyrolysis of the obtained SSP green bodies at 1000°C. Due to the strong influence of polymer structure on the microstructure of final ceramics, the SSP-derived CNTs-SiCN nanocomposites clearly show the homogeneous distribution of the CNTs in the SiCN matrix while the physically-blended-precursor derived CNTs-SiCN nanocomposites exhibit serious aggregation and entangling of the CNTs in the SiCN matrix. With the same CNT content in the feed, the SSP-derived CNTs-SiCN nanocomposites possess significant improvements of electromagnetic (EM) absorbing properties compared to those from physically-blended-precursors, due to the quality of the dispersion of CNTs in the ceramic matrices.

The preparation of a fluorine-containing synergistic nonfouling/fouling-release surface, using a b-PFMA-PEO asymmetric molecular brush possessing both poly(ethylene glycol) (PEO) and poly(2,2,2-trifluoroethyl methacrylate) (PFMA) side chains densely distributed on the same repeat unit along the polymeric backbone, is reported. On the basis of the poly(Br-acrylate-alkyne) macroagent comprising two functionalities (alkynyl and 2-bromopropionate), which is prepared by reversible addition-fragmentation chain transfer homopolymerization of a new trifunctional acrylate monomer of Br-acrylate-alkyne, b-PFMA-PEO asymmetric molecular brushes are obtained by concurrent atom transfer radical polymerization and Cu-catalyzed azide/alkyne cycloaddition "click" reaction in a one-shot system. A spin-cast thin film of the b-PFMA-PEO asymmetric molecular brush exhibits a synergistic antifouling property, in which PEO side chains endow the surface with a nonfouling characteristic, whereas PFMA side chains display the fouling-release functionality because of their low surface energy. Both protein adsorption and cell adhesion tests provided estimates of the antifouling activity of the asymmetric molecular brush surfaces, which was demonstrated to be influenced by the degree of polymerization of the backbone and the length of the PEO and PFMA side chains. With compositional heterogeneities, all asymmetric molecular brush surfaces show considerable antifouling performance with much less protein adsorption (at least 45% off, up to 75% off) and cell adhesion (at least 70% off, up to 90% off) in comparison with a bare surface.

A fluorine-containing anti-fouling surface was developed at a molecular-length scale by using a compositional heterogeneous polymer brush, which involves hydrophilic poly(ethylene glycol) (PEG) brushes with non-fouling functionality, fouling-release hydrophobic poly(2,2,3,3,3-pentafluoropropyl acrylate) (PPFA) brushes and catechol moieties, an important component of mussel adhesive proteins (MAPs), to anchor asymmetric polymer brushes onto surfaces. A well-defined PtBBPMA-co-PPEGMEMA-co-PDOMA macroinitiator was firstly prepared by RAFT copolymerization of tert-butyl 2-((2-bromopropanoyloxy)methyl)acrylate (tBBPMA) consisting of a Br-containing ATRP initiating group, poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) macromonomer and N-(3,4-dihydroxyphenethyl) methacrylamide (DOMA) bearing an adhesive anchoring group of the catechol moiety. ATRP of PFA was then directly initiated by PtBBPMA-co-PPEGMEMA-co-PDOMA to afford (PtBA-co-PPEGMEMA-co-PDOMA)-g-PPFA asymmetric polymer brush via the grafting-from strategy. The asymmetric polymer brush surface could form a layer of amphiphilic brushes on the substrate with the assistance of adhesive anchoring groups through the drop coating technology. With dense heterogeneous brush conformation at a molecular-length scale, (PtBA-co-PPEGMEMA-co-PDOMA)-g-PPFA-based surface shows considerable anti-fouling performance with less protein adsorption (81.9% off) and cell adhesion (83.6% off) in comparison with bare surface.

Propylene carbonate (PC)-based nano-fluids (NFs), containing only 2 ppm TiO2 nano-particles, exhibit more than 60% higher negative impulse breakdown voltage than that of base liquid. It is found that the resistance of the test gap containing PC remains basically invariable when subjected to high amplitude voltage before the development of electrical breakdown. However, for the NF case, the resistance increases by a factor. Moreover, compared with PC, the streamers in NFs are more complex branched. These experimental results indicate that the charge carriers in NFs can be effectively captured and scattered by nano-particles, which is verified by means of the thermally stimulated current method.

To date, research on air battery catalysts has been mainly focused on finding materials with a high oxygen reduction reaction (ORR) catalytic activity. However, the high cost of platinum catalysts restricts their commercialization. Herein, we report a simple hydrothermal-calcination method to fabricate low-cost NiMn2O4 -based Ni-Mn bimetallic oxides. The Ni-Mn-600 sample showed a high onset potential (1.01 V vs. RHE), which was more positive than that for 20 wt% Pt/C (0.97 V vs. RHE), and its half-wave potential (0.78 V vs. RHE) was comparable to that for 20 wt% Pt/C (0.84 V vs. RHE). Moreover, Ni-Mn-600 as an Al-air battery air–cathode catalyst exhibited a high discharge plateau of 1.42 V and peak power density of 100.45 mW cm−2, which outperformed those for 20 wt% Pt/C (1.34 V and 76.10 mW cm−2). The high ORR electrocatalytic activity of Ni-Mn-600 may be attributed to the nanorod morphology and high ratio of (Mn3++Mn4+)/Mn2+ and Ni3+/Ni2+. This work demonstrated that NiMn2O4-based Ni-Mn bimetallic oxides as cathode catalysts have good research prospects in aluminum-air batteries and other energy applications.

Silicon suboxide (SiOX) is a promising anode material for lithium ion battery (LIB). However, oxygen-dependent SiOX poses a great impact on its cycling stability, which is difficult to controllably prepare. Additionally, the aggregation of nano-scale SiOX restricts the diffusion of lithium ion and structural stability during cycles. Herein, we realize the controllable preparation of porous SiOX/C sheets with various oxygen content and graphite-like carbon as anode materials of LIB. It is found that high oxygen content and a 3-dimensional network in SiOX/C can ensure high structural stability during cycles. As-prepared SiOX facilitates the growth of graphite-like carbon with high defect density, improving their electron and ion conductivity. As-prepared SiOX@C sheets deliver superior reversible capacity, cycling stability and rate performance (the second discharging capacity of 717.4 mAh g−1 at 100 mA g−1 with high initial Coulombic Efficiency of 64.08% is obtained; its capacity retention is as high as 100.44% against the second discharging capacity after 200 cycles; at a high current density of 2000 mA g−1, its reversible capacity still remains 389 mAh g−1). This work provides a novel and simple approach to controllably prepare disproportionated SiOX@C sheets with the 3-dimensional network as ultrastable SiOx-based anode materials of LIB for practical application.

In this study, a micromechanics framework considering both interface diffusion and matrix creep is proposed to analyze the creep behavior of PM alloys. Based on the mean-field micromechanics theory, the creep strain rate induced by interface diffusion in the particulate composite under uniaxial loading is derived. The creep strain is introduced as an eigenstrain into the inclusion, whose rate is expressed in the tensor-form with three non-zero components and naturally satisfies incompressibility. An incremental analysis procedure is employed to model the creep behavior of particulate composites. The aluminum alloy is treated as a composite material, with precipitated particles as the reinforcements. We then adopt the proposed micromechanics approach to study the creep behavior of the powder metallurgy aluminum alloy with continuous precipitation, accounting for both the creep of matrix and the creep induced by interfacial diffusion along the precipitate/matrix interface. The predicted creep curves agree well with experimental results and the explanation for the creep phenomenon has never been proposed before. We have also derived the minimum or steady-state creep rate of the alloy by the micromechanics approach, which turns out to be similar to the expression of improved power-law creep with a threshold stress.

Silicon suboxide (SiOx) is considered as one of the potential candidates for next-generation lithium-ion battery (LIB) anode materials. However, the application of this material is limited by volume change during the discharging and charging process and its low initial cycle Coulombic efficiency (ICE). Herein, we report a controllable and cost-effective route to synthesize the SiOx/MgO/Mg2SiO4/C (SMC) composite using magesiothermic reaction (MTR), hot-water treatment, and carbonization process. Moreover, the composite exhibits a hierarchical buffer structure composed of microspheres. Because of its special dehydration ability to disrupt the hydrolytic cycle, the introduction of MgO is proved to be beneficial to LIBs’ cycling performance and rate capability. Besides, with the formation of Mg2SiO4, the consumption of SiO2 improves the ICE of the SMC anode to 87.48%. The hierarchical microstructure makes the resultant SMC anode exhibit a stable reversible capacity of 550 mAh g−1, which means a high capacity retention ratio of 78.81% after 200 cycles. Furthermore, the specific capacity of SMC anode keeps around 600 mAh g−1 at the current density of 800 mA g−1, showing superb rate performance. This work provides a novel approach to taking advantage of by-products of MTR and also demonstrates the potential of industrial application of SiOx/C anodes.

Various gas sensors have made considerable improvements to the quality of people’s lives. However, in most cases, changing of materials is necessary to adapt to the changing of the target gas, which limits the further application of gas sensors. To meet this challenge, in this work, molecular imprinting (MI) technology is introduced. Acrylic acid is used as a functional monomer, while gas molecules, including acetone, are used as templates. The MI process with an acetone template helps improve the acetone selectivity of TiO2 by up to 1.74–2.80 times. Moreover, it proved that other templates can increase the corresponding selectivity by at least 1.5 times by using the same matrix material. These results demonstrate the potential importance of the MI process in constructing a highly compatible gas sensor industry. Beyond this, the MI process has proved to achieve an ultrahigh specific surface area of 384.36 m2 · g−1. The optimal acetone sensor exhibits desirable comprehensive performance compared with other reports. An excellent TiO2 based prototype acetone sensor working at 300 °C with a low detection limit of 18 ppb is obtained.

A series of well-defined amphiphilic asymmetric polymer brushes containing hetero side chains, hydrophobic polystyrene (PS) and hydrophilic poly(ethylene glycol) (PEG), was synthesized by sequential reversible addition–fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). The well-defined polyacrylate-based backbones (Mw/Mn ≤ 1.22), PtBBPMA-co-PPEGMEMA, were first prepared by RAFT copolymerization of tert-butyl 2-((2-bromopropanoyloxy)methyl)acrylate (tBBPMA), which bears a Br-containing ATRP initiating group and a poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) macromonomer. The reactivity ratios determined by Fineman–Ross and Kelen–Tudos methods showed that both monomers tended to form random copolymers. The density of the Br-containing ATRP initiating group could be well tuned by the feeding ratio of comonomers. ATRP of styrene was directly initiated by PtBBPMA-co-PPEGMEMA without polymeric functionality transformation to afford well-defined (PtBA-g-PS)-co-PPEGMEMA polymer brushes (Mw/Mn ≤ 1.26) via the grafting-from strategy. The pendant tert-butoxycarbonyls in the backbone were selectively hydrolyzed to carboxyls for providing (PAA-g-PS)-co-PPEGMEMA polymer brushes. Both polymer brushes with the exact same side chains, but different backbones, self-assembled into large compound micelles and bowl-shaped micelles in aqueous media, respectively. This is a direct and strong example to address the importance of the properties of the backbone of a graft copolymer on its self-assembly behavior. Interestingly, different from common spherical micelles, which can just solubilize hydrophobic compounds within their core, the large compound micelles formed by (PtBA-g-PS)-co-PPEGMEMA polymer brushes can encapsulate hydrophilic Rhodamine 6G and hydrophobic pyrene separately or simultaneously.

Many efforts have been undertaken towards the synthesis of vertically stacked two-dimensional (2D) crystals due to their unique electronic and optical properties. Here, we present direct molecular beam epitaxy (MBE) growth of a MoS2/graphene heterostructure by a strict epitaxial mechanism. By combining Raman, photoluminescence, transmission electron microscopy characterizations and first-principles calculations, we find that there exists a strain effect and strong interlayer coupling between MoS2 and graphene resulting from the intrinsic crystal lattice mismatch, which could generate potential metallic behavior of the heterostructure. The direct epitaxial technique applied here enables us to investigate the growth mechanisms and interlaminar interaction of 2D heterostructures without sample handling and transfer, and offers a new approach to synthesize multilayer electronic and photonic devices.

To satisfy the growing demand for military and civil applications, it is necessary to develop high-efficiency microwave-absorbing materials. Herein, a pyrolysis process was developed to construct FeOx/Fe/C composites using filter papers saturated with ferric nitrate solution as the precursor. The three-dimensional textures of filter paper are well maintained during the pyrolysis process. Ferric nitrate is decomposed to Fe2O3 and subsequently reduced to Fe3O4 and Fe nanoparticles embedded in the carbon matrix via carbothermal reduction. Various gases produced during the pyrolysis process create foam and generate additional nanoscale pores in the carbon matrix. The chemical composition and structure of composites can be tailored by controlling the pyrolysis conditions. The microwave absorption properties of FeOx/Fe/C composites are closely related to the chemical composition and structure. The optimized product shows excellent microwave absorption properties: The strongest reflection loss (RL) is −37 dB at ∼12 GHz; the effective absorption bandwidth (RL

Asymmetric molecular brushes emerge as a unique class of nanostructured polymers, while their versatile synthesis keeps a challenge for chemists. Here we show the synthesis of well-defined asymmetric molecular double-brushes comprising two different side chains linked to the same repeat unit along the backbone by one-pot concurrent atom transfer radical polymerization (ATRP) and Cu-catalyzed azide/alkyne cycloaddition (CuAAC) reaction. The double-brushes are based on a poly(Br-acrylate-alkyne) homopolymer possessing an alkynyl for CuAAC reaction and a 2-bromopropionate initiating group for ATRP in each repeat unit. The versatility of this one-shot approach is demonstrated by CuAAC reaction of alkynyl/poly(ethylene oxide)-N3 and ATRP of various monomers. We also show the quantitative conversion of pentafluorophenyl ester groups to amide groups in side chains, allowing for the further fabrication of diverse building blocks. This work provides a versatile platform for facile synthesis of Janus-type double-brushes with structural and functional control, in a minimum number of reactions., Producing well-defined polymer compositions and structures facilitates their use in many different applications. Here the authors show the synthesis of well-defined asymmetric double-brushes by a one-pot concurrent atom transfer radical polymerization and Cu-catalyzed Click reaction.

Owing to the twist degree of freedom (DOF), soft torsional motion can increase flexibility and quickly achieve positional and attitude adjustment in complex and narrow spaces. Compared with bending actuator, there is much less research on soft torsional actuators. Current soft torsional actuators often accompany with other motion couplings, so it is difficult to provide pure twist. Based on the princi-ple of spiral chambers with pneumatic driving, a new type of torsional actuator module is designed in this paper. Combined with finite element simulation, the ge-ometric parameters of the module are optimized and then fabrication is carried out by two stages. In order to control the module, a kinematic model, which is the relationship between the air pressure and the twist angle, is established by means of experimental calibration. Finally, a test platform is set up, which is used for measuring the static characteristics of the designed module. The maximum ob-tainable torsion angle and torque are obtained separately through the experiments on torsion angle test and torsion torque test.

The rational design of economical air cathodes or electrocatalysts with high electrocatalytic activity and durability for both non-aqueous lithium-oxygen (Li-O2) and alkaline electrolyte aluminum-air (Al-air) batteries is a critical factor for promoting the practical applications. Herein, we report the fabrication of graphitic layers covered with Co9S8 nanoparticles immobilized inside N,S dual-doped hierarchical porous carbon nanofibers by a facile and one-step electrospinning method combined with a pyrolytic process. When employed as free-standing electrodes for a Li-O2 battery and an Al-air battery, the as-prepared Co9S8@G/NS-PCNFs deliver excellent battery performances and afford comparable catalytic performance as that of a 20 wt% Pt/C electrode. The results show that the superior battery performance of the Co9S8@G/NS-PCNF cathode can be attributed to the synergistic effect between the catalytic behavior of the uniformly distributed Co9S8 nanoparticles and the textural properties of the N,S dual-doped hierarchical porous carbon nanofibers. Our findings open a new direction for designing nonprecious hybrid metal sulfide carbon architectures to replace costly Pt/C electrodes and indicate their promising application in next-generation metal-air batteries.

Integrated fabrics with a smart heating control system (HCS) are attractive in warming and thermotherapy for human healthcare management. Metal nanofibers (NFs) networks with high flexibility, conductivity and gas permeability are ideal functional materials for wearable electronics. Herein, a novel sandwich-structural (Ag NFs/fabrics/Pt NFs) textile for a HCS is constructed, where a Ag NF network film was functioned as a wearable heater and Pt NF network arrays were functioned as wearable temperature sensors. Conductivity and mechanical stability of the metal NFs were enhanced by crosslinking the free-standing fiber networks, resulting in high thermo-stability, thermal resistance (163.5 °C W-1 cm2) and temperature sensitivity (0.135% °C-1) of the HCS. The HCS can simultaneously realize heating and temperature distribution detection, demonstrating only 0.57% average error between the simulated resistance-to-temperature diagram of Pt NF arrays and actual temperature mapping. In addition, the HCS can be stuck on the skin for thermochromic fabrics, real-time heating and temperature detection/control through a Bluetooth device in a smartphone wirelessly.

A series of fluorine-containing amphiphilic ABC triblock copolymers comprising hydrophilic poly(ethylene glycol) (PEG) and poly(methacrylic acid) (PMAA), and hydrophobic poly(p-(2-(4-biphenyl)perfluorocyclobutoxy)phenyl methacrylate) (PBPFCBPMA) segments were synthesized by successive atom transfer radical polymerization (ATRP). First, PEG-Br macroinitiators bearing one terminal ATRP initiating group were prepared by chain-end modification of monohydroxy-terminated PEG via esterification reaction. PEG-b-PBPFCBPMA-Br diblock copolymers were then synthesized via ATRP of BPFCBPMA monomer initiated by PEG-Br macroinitiator. ATRP polymerization of tert-butyl methacrylate (tBMA) was directly initiated by PEG-b-PBPFCBPMA-Br to provide PEG-b-PBPFCBPMA-b-PtBMA triblock copolymers with relatively narrow molecular weight distributions (Mw/Mn ≤ 1.43). The pendant tert-butyoxycarbonyls were hydrolyzed to carboxyls in acidic environment without affecting other functional groups for affording PEG-b-PBPFCBPMA-b-PMAA amphiphilic triblock copolymers. The critical micelle concentrations (cmc) were determined by fluorescence spectroscopy using N-phenyl-1-naphthylamine as probe and the self-assembly behavior in aqueous media were investigated by transmission electron microscopy. Large compound micelles and bowl-shaped micelles were formed in neutral aqueous solution. Interestingly, large compound micelles formed by triblock copolymers can separately or simultaneously encapsulate hydrophilic Rhodamine 6G and hydrophobic pyrene agents.

Surfaces modified with amphiphilic polymers can dynamically alter their physicochemical properties in response to changes of their environmental conditions; meanwhile, amphiphilic polymer coatings with molecular hydrophilic and hydrophobic patches, which can mitigate biofouling effectively, are being actively explored as advanced coatings for antifouling materials. Herein, a series of well-defined amphiphilic asymmetric polymer brushes containing hetero side chains, hydrophobic polystyrene (PS) and hydrophilic poly(ethylene glycol) (PEG), was employed to prepare uniform thin films by spin-casting. The properties of these films were investigated by water contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and quartz crystal microbalance (QCM). AFM showed smooth surfaces for all films with the roughness less than 2 nm. The changes in water contact angle and C/O ratio (XPS) evidenced the enrichment of PEG or PS chains at film surface after exposed to selective solvents, indicative of stimuli- responsiveness. The adsorption of proteins on PEG functionalized surface was quantified by QCM and the results verified that amphiphilic polymer brush films bearing PEG chains could lower or eliminate protein-material interactions and resist to protein adsorption. Cell adhesion experiments were performed by using HaCaT cells and it was found that polymer brush films possess good antifouling ability.

The influence of grating parameters, including the diffraction efficiency and ruling density, on the performance of high-power blue external-cavity (EC) semiconductor lasers has been studied. We find that for the Littrow-type EC laser with a zeroth-order diffracted beam as a coupling output, the high zeroth-order diffraction efficiency benefits the high external light extraction efficiency, and the high first-order diffraction efficiency contributes to the low threshold current and the wide wavelength tuning bandwidth. By using a grating with a zeroth-order diffraction efficiency of 76% and a first-order diffraction efficiency of 11.5%, the external light extraction efficiency can reach up to 80% with an output power of more than 1200 mW and a tuning bandwidth of 3.6 nm. When a grating with a first-order diffraction efficiency of 58.5% and a zeroth-order diffraction efficiency of 28.6% is used, the threshold current is reduced by 46% at the central Fabry-Perot resonance wavelength. Moreover, a tuning bandwidth of 8.3 nm ranging from 442.2 nm to 450.5 nm with an output power of more than 500 mW is achieved. Besides, we also find that the high ruling density is helpful in obtaining narrow lasing linewidth, especially for the EC laser system injected with low current. By using a grating with a ruling density of 2400 grooves/mm, the spectral linewidth of the EC laser can be narrowed to be 0.02 nm with an operating current of 300 mA. As the injection current is increased, the lasing linewidth is little affected by the ruling density of the grating due to the broadened feedback spectrum by the flattening of gain spectrum. The results above shed light on the improvement of the performance of EC lasers by selecting appropriate parameters for the grating.

We grow high-quality two-dimensional hexagonal boron nitride (h-BN) films on copper pockets by chemical vapor deposition. A piece of sapphire embedded in the pocket serves as an oxygen supply during the growth process. To obtain clean h-BN films, source powders are placed in a U-shaped quartz tube and heated up in a water bath without the carrier-gas flow. These films are characterized by using SEM, Raman, XPS, and selected area electron diffraction analyses. As dielectric substrates, h-BN films significantly enhance the charge-carrier mobility of graphene transistors. This facile and robust method can be a scalable approach to synthesize large-area high-quality h-BN films for related electronic applications.

A competing sulfur‐capture principle jointly with strict epitaxial mechanism is first proposed for the initial topography evolution of MoS2 domains with Mo or S terminations on the graphene template. The electron transfer between Gr and MoS2 is also experimentally evaluated. The understanding for optimizing the experimental design to synthesize the desirable heterostructures for various applications is provided.

To evaluate the effectiveness of acellular bovine pericardium grafts (Normal GEN®) used as scaffolds for conjunctival reconstruction. The acellular bovine pericardium graft and the amnion graft were implanted into the bulbar conjunctival defects of adult rabbits. Conjunctival samples of implanted materials and blank defect controls were observed at day 3, 7, 14, 21, 28, and 56 postoperatively. Histological examination was observed at day 14, 28, and 56 of surgery, including hematoxylin–eosin staining, periodic acid-Schiff staining, and Masson’s trichrome staining, while immunofluorescent microscopy was observed at 14 days and 28 days after surgery. Results were compared among the Normal GEN®, amnion, and blank defect controls. All three groups showed complete conjunctival reconstruction. Wounds that were not grafted closed by formation of conjunctival scar characterized by a linear array of densely packed collagen fibers in Tenon’s capsule. Subepithelial tissue in the grafted groups comprised a loosely organized network of randomly oriented collagen that resembled that of the normal bulbar conjunctiva. However, there was a dense layer of aligned collagen between the conjunctival Tenon’s capsule and the sclera in the NormalGEN® group, about 250 μm in thickness. Implantation of the NormalGEN® graft promoted the formation of conjunctiva as a kind of scaffold both in structure and in function. It had more advantageous mechanical properties than the amnion, strong and elastic, during the period of conjunctival reconstruction.