Search

A Ni60/Ni-WC composite coating was fabricated by the plasma spraying technology and microstructure of the coating was analyzed. Moreover, erosion resistance of the coating under different erosion angles was tested. Results demonstrated that the coating has lamellar structures and contain some pores. WC particles distribute evenly in the coating and bond well with the parent phase. When the erosion angle increase, the weight loss of the erosion-induced coating increases firstly and then decreases, showing plastic-brittle composite erosion characteristics.

Lead-free perovskite solar cells (PSCs) have attracted interest among scientists searching for eco-friendly energy harvesting devices. Herein, the effects of ozone exposure on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) in lead-free tin halide PSCs as a facile and low-cost process for improving device performance are analyzed. Two types of tin-based PSCs and one typical lead-based PSC were fabricated. The ozone exposure on PEDOT:PSS increases the short-circuit current density (JSC) and the fill factor (FF) of PSCs in all cases with perovskite grain enlargement and hole-mobility enhancement of the devices, respectively. For open-circuit voltage (VOC), the outcome depends on the band gap and the energy levels of the perovskite films. While ozone exposure treatment is favorable for PEA0.15FA0.85SnI3-based tin PSCs, VOC decreases with ozone exposure in the case of Ge:EDA0.01FA0.98SnI3-based tin PSCs because of a misalignment of the energy levels. Regardless, the efficiency of PEA0.15FA0.85SnI3-based tin PSCs increases from 8.7 to 10.1% when measured inside a glovebox upon ozone exposure of PEDOT:PSS. The efficiency of Ge:EDA0.01FA0.98SnI3-based tin PSCs increases from 6.8 to 8.1%, and the devices retain an efficiency of 5.0% even after 50 days in air.

The selective synthesis of energetically less favorable ring-shaped nanostructures by liquid phase synthetic chemistry is a huge challenge. Herein, we report a precise synthesis of carbon nanorings with a well-defined morphology and tunable thickness based on asymmetric intramicellar phase-transition-induced tip-to-tip assembly via mixing hydrophobic long-chain octadecanol and block copolymer F127. This orientational self-assembly depends on the hydrophobicity difference of the intermediate’s surface, which triggers directional interactions that surpass the entropy cost of undesired connections and help assemble intermediates into defined ringlike structures. Based on a ringlike template, carbon nanorings with adjustable sizes can be attained by changing synthetic variables. More importantly, diverse units including crescentlike, podlike, and garlandlike nanostructures can also be created through controlling the kinetics of the self-assembly process. This discovery lays a solid foundation for the challenging construction of such a precise configuration on the nanoscale, which would not only promote fundamental studies but also pave the way for the development of advanced nanodevices with unique properties., Carbon nanorings with a well-defined morphology and tunable thickness have been selectively synthesized via asymmetric intramicellar phase-transition-induced tip-to-tip assembly.

Long-range surface plasmon resonance (LRSPR) sensor has attracted extensive attention from research institutions and commercial companies due to its label-free detection, real-time analysis, high detection accuracy (DA) and high sensitivity. In this paper, a novel, simple, and effective rotating angle modulation (RAM) method for the metal-graphene structure LRSPR sensor is proposed. Compared with the general SPR sensor, the metal-graphene structure LRSPR sensor has a narrower full width at half maximum (FWHM) and a very high DA, especially the metal material is copper (Cu). The theoretical analysis for the Cu-graphene structure LRSPR sensor using RAM method shows that the FWHM, sensitivity and figure of merit (FOM) of the proposed sensor can be 0.74°, 320.4°/RIU and 498.24/RIU, respectively. In addition, this method enables the LRSPR sensor to obtain good measurement results even with the low-resolution rotating device and effectively reduces the dependence of the sensor on the high-resolution expensive rotating device. A preliminary comparative experiment for the SPR sensor has proved this new method. Finally, the concept of combining the RAM and general incident angle methods is proposed to provide the sensor with a large measuring range and low optical losses. We believe that this method can provide a favorable reference for solving the shortcomings of LRSPR sensors, such as complex structure, limited sensitivity and high cost, so that it can be widely promoted and applied in biological detection, medical assay, chemical investigation, etc.

This paper presents a theoretical model based on Biot theory to investigate the sound transmission loss (STL) of a pyramidal lattice sandwich structure lined with porous material. This theory is mo...

FV520B stainless steel is an important material for compression turbine impellers. Its corrosion resistance at high temperatures is critical for the manufacturing and service reliability management...

Aiming at improving the energy collection efficiency for low-frequency vibrations, a new spider-web shaped plate (SWSP) is designed to achieve the target of increasing the amplitude with decreasing the eigen-frequency (abbreviated as IADEF) in a piezoelectric/magnetoelectric composite convertor integrating with a magnet. Through analytically optimizing the proposed SWSP, the increasing of output voltage with the decreasing of eigen-frequency can be accomplished effectively at both micro- and mesolevels. The above expected IADEF effect is experimentally observed and further verified with fabricated SWSP prototypes. Compared to a conventional one, the optimized SWSP decreases the eigen-frequency by a large percentage and remarkably increases the output voltage. An optimal positioning of the magnet is found to be conducive to the maximization of the output voltage, while the geometrical contribution of the magnet design to IADEF is also observed. This work is of great significance for the design of high-performance low-frequency energy convertor as well as the development of self-powered devices and battery-free electromechanical systems.

Deep geological repository is a favorable choice for the long-term disposal of nuclear wastes. Bentonite–sand mixtures have been proposed as the potential engineered barrier materials because of their suitable swelling properties and good ability to seal under hydrated repository conditions. To investigate the effects of sand grain size on the engineering performance of bentonite–sand mixtures, we prepare five types of bentonite–sand mixtures by mixing bentonite with sand of varying particle size ranges (0.075–0.25 mm, 0.25–0.5 mm, 0.5–1 mm, 1–2 mm and 2–5 mm, respectively). We carry out sequential oedometer tests under different simulated repository conditions, including constant vertical stress (CVS), constant stiffness (CS) and constant volume (CV) conditions. The microstructural heterogeneity and anisotropy of these soil mixtures are characterized through the quantitative analysis of micro-CT scanning results. Experimental results reveal that both sand grain size and boundary condition significantly influence the swelling of soil mixtures. Under three conditions, the temporal evolutions of swelling stress and strain follow similar trends that they increase faster at the beginning and gradually stabilize afterward. Comparing the ultimate values, swelling strains follow CVS > CS > CV, while swelling stresses follow CV > CS > CVS. Under CS boundary conditions, as the stiffness coefficient increases, the swelling pressure increases and the swelling strain decreases. CT results further indicate that mixtures with larger sand inclusions are more structurally heterogeneous and anisotropic, resulting in increased inter-particle friction and collision and a higher energy dissipation during the swelling process. Moreover, the non-uniform distribution of bentonite in local zones would be intensified, which plays an important role in compromising swelling behavior. Therefore, soil samples mixed with larger sand particles present a smaller swelling stress and strain values. This study may guide the choice of engineered barrier materials toward an improved design and assessment of geological repository facilities.

Bi2O3 is a strong candidate as the optimal aqueous battery anode material, but suffers from its poor stability and rate performance (a result of fragile structure and poor conductivity). Herein, two self-derived Bi species, interstitial-Bi liberated from Bi2O3 unit cell and colonized surface nano-Bi, function synergistically in the Bi2O3 by creating a new electronic state in the energy gap and tuning the Bi/Bi2O3 interface coordination. As a result, electronic conductivity, ionic diffusion, and structural stability are fully enhanced, leading to a package of optimal electrochemical performances. Our self-enhanced strategy may thereof serve in design of functional oxide complexes for electrochemical energy conversion and storage.

Ferroelectric materials are promising for solar energy conversion due to the unique spontaneous polarization effect, leading to effective control of electron-hole recombination and potentially high power conversion efficiency of perovskite solar cells. Herein, the ultrathin ferroelectric hafnia alumina (HfAlO) films were obtained by atomic layer deposition and applied to modify the electron transport layer of PSCs. The XPS and AFM characterizations indicate that the Hf0.39Al0.10O films feature smooth, dense, and compact surface morphology. For the devices incorporating the ultrathin HfAlO films, the oriented ferroelectric effect-induced spontaneous polarization and internal electric field are crucial factors to enhance the charge separation during charge transfer. Accordingly, the short circuit current, open-circuit voltage, and power conversion efficiency (PCE) are increased by 11.8%, 9.0%, and 29.8%, respectively. Moreover, the HfAlO incorporating devices retained ~ 80% of the original PCE after 500 h ageing, much better than that of the pristine devices showing the retention of only ~ 50% of the original PCE.

The power conversion efficiency (PCE) of solution-processed organic–inorganic hybrid perovskite solar cells has been drastically improved. Despite this considerable progress, systematic research on...

Low back pain associated with degenerative disc diseases has been a major health concern that brings suffering to the patients physically and economically. Many existing therapeutic strategies provide short-term relief of symptoms rather than treatment of the underlying cause. Development of an engineered tissue for disc regeneration is still in its infancy due to the limited autologous healthy disc cell source from the patients. It is also challenging to mimic the complexity of micro-architecture in the native disc tissue that determine their unique structural properties. To date, simple tissue models that mimic the annulus fibrosus (AF) micro-environment for understanding the potential of mesenchymal stem cells (MSCs) in AF tissue engineering are still lacking. In this study, the assembly of a coiled hydrogel microfiber has shown its capability to encapsulate MSCs and create an engineered tissue model that mimics the multiple lamellae of native AF. Using this model, we investigated the potential of MSCs that were previously induced by ascorbic acid (AA). Compared to non-induced MSCs, AA-induced MSCs exhibited significant increase in AF-associated biomarkers during later development in the engineered AF tissue model and also encouraged collagen accumulation through the down-regulated catabolic gene MMP1 and upregulated anti-catabolic gene TIMP1. Furthermore, AA-induced MSCs exhibited a Col2/Col1 ratio closer to that of a native AF tissue. These results suggested that AA-induced MSCs could be a potential cell source for AF tissue engineering and this established tissue model may provide a simple tool for successful AF tissue engineering strategies in the future.

A finite element model of temperature field for plasma spraying preset MCrAlY coating during laser cladding was constructed using ANSYS parametric design language (APDL) in accordance to characteristics of preset laser cladding. Influencing laws of laser cladding parameters on temperature field were analyzed. Results show that laser power influences temperature field of cladding samples more than laser scanning speed. Experimental results agree well with simulation results, which prove the accuracy and reliability of the constructed calculation model of temperature field. Heating and cooling laws in the laser cladding process could be mastered through this calculation model. Research conclusions provide some references to optimization parameters in preparing high-performance laser cladding coatings.

Density functional calculations have been performed to explore the possible structures of Sc3NC@C86 and Sc3NC@C88 metallofullerenes. Ten lowest energy isomers of C866− and six lowest energy isomers of C886− are selected as possible host cages for encapsulating Sc3NC cluster. The results reveal that four IPR-obeying Sc3NC@D3(63761)-C86, Sc3NC@C2V(63751)-C86, Sc3NC@D2(81738)-C88, and Sc3NC@Cs(81735)-C88 molecules are stable both kinetically and thermodynamically. The inner Sc3NC cluster adopts a planar configuration inside the fullerene C86 and C88 cages, similar to the reported Sc3NC@Ih(7)-C80 and Sc3NC@C2(22010)-C78. Furthermore, the infrared spectra have also been explored to help future experimental characterization.

The precise control over high-order DNA architecture assembly might be challenging due to complicated circuit design and functional unit synthesis. Here, we show an enzyme-free, catalytic assembly to construct nanometer and micrometer architectures in a bottom-up manner and applied them in nanoparticles and cell assembly.

Among small molecule organic materials, tris(4-(1-phenyl-1H-benzo[d]imidazole)phenyl)phosphine oxide (TIPO) and 2,4,6-tris(4-(1-phenyl-1H-benzo[d]imidazol)phenyl)-1,3,5-triazine were newly synthesised and introduced into an n-type interlayer in planar perovskite solar cells for effective electron transport. The small molecule materials contain phenyl benzimidazole, which is combined with a phosphine oxide core or a triazine ring core and contributes to the improvement of charge extraction and stability. As the constituent molecules—phosphine oxide and benzimidazole—have strong polarity properties and π-electrons, the molecules induce passivating defects towards improving charge transport and flattening the surface morphology. Moreover, the stability of the device was increased due to the introduction of the TIPO material as the passivation and protection layer. In this electron extraction analysis, electrical resistance and surface morphology investigations were carried out via space charge-limited current, photoluminescence, impedance, and atomic force microscopy analyses.

Fully inorganic black orthorhombic (B-γ) CsSnI3 has become a promising candidate for perovskite solar cell (PSC) thanks to its low toxicity and decently high theoretical power conversion efficiency (PCE). However, so far, the reported PCE of the B-γ CsSnI3 PSC is still not comparable with its lead-based or organotin-based counterparts. Herein, a mixed electron transport layer (ETL) composed of ZnO nanoparticles (NPs) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is incorporated into inverted B-γ CsSnI3 PSCs. The mixed ETL exhibits the merits of both ZnO and PCBM. The highest PCE of 6.08% was recorded for the PSC with mixed ZnO-PCBM ETL, which is 34.2% higher than that of the device with plain PCBM ETL (PCE of 4.53%) and 28.8% superior to that of plain ZnO ETL-based device (PCE of 4.72%). Meanwhile, the mixed ZnO-PCBM ETL-based PSC retained 71% of its initial PCE under inert conditions at room temperature after 60 days of storage and maintained 67% PCE after 20 days of storage under ambient air at 30% relative humidity and room temperature.

Necking defects have long troubled the application of cross-wedge rolling technology in aluminium alloy shaft parts. To accurately predict necking defects, new judgement conditions are established based on the thermal performance of 6082 aluminium alloy. The limit-sectional shrinkage without necking defects is achieved by combining theoretical calculation and finite-element model analysis, which couples heat transfer and deformation. In this paper, a 6082 aluminium alloy extruded rod with a 40 mm diameter rolled at a preheated temperature of 500 °C and a rolling angular velocity of 1 rad/s is taken as an example. The simulation and experimental results show that necking defects do not occur on the rolled pieces if the sectional shrinkage is below the limit-sectional shrinkage but will occur when the sectional shrinkage is above it. The results prove that the prediction model of necking defects in cross-wedge rolling of 6082 aluminum alloy is feasible, and this research provides a theoretical basis for the qualified aluminum alloy shafts produced by the cross-wedge rolling.

A novel carbon allotrope is predicted by first-principles calculations. This allotrope is obtained by replacing one of the two atoms in the primitive cell of diamond with a carbon tetrahedron, thus it contains five atoms in one primitive cell, termed T5-carbon. The stabilities of T5-carbon are checked in structural, thermal and vibrational calculations. T5-carbon is a wide band gap semiconductor with an indirect band gap of 4.30 eV, and has a lattice thermal conductivity of 409 W/mK. Mechanical analyses reveal that T5-carbon shows good mechanical performances. Furthermore, by modifying T5-carbon with replacing some carbon atoms with Si or Ti atoms, we can obtain SiC4 or TiC4 structures. Importantly, the TiC4 system has a moderate conduction and valance band edges, comparable larger absorption capacity of visible light and smaller effective masses of electron and hole carriers than TiO2, confirming its photocatalysis applications.

EHD (Electrohydrodynamic) printing is a promising technique for alternative fabrication of highresolution micro- and nanostructures without employment of any molds or photo-masks However, the printing precision can be easily influenced by the printing conditions, such as applied voltage, printing distance (the distance between the nozzle tip and the substrate), and flow rate. Unfortunately, up to now there was no work which analyzed those influencing factors in-depth and systematically by theory and numerical simulation. In this paper, the theory of EHD printing was presented and the effect of applied voltage, printing distance, and flow rate on the width of printed line was analyzed by numerical simulation. The simulation results showed that the width of printed lines is proportional to printing distance, nozzle size, and flow rate. However, it is inversely proportional to the applied voltage.

The vibration and damping performances of carbon fiber-reinforced polymer (CFRP) three-dimensional double-arrow-head (3D DAH) auxetic metamaterials are investigated in this paper. The negative Poisson’s ratio effects of the CFRP 3D DAH auxetic metamaterials are analytically studied by the energy method. 3D finite element models based on Modal Strain Energy approach are developed to analyze their vibration and damping characteristics. To validate the numerical models in the present study, the CFRP 3D DAH auxetic metamaterials are designed and manufactured. The sine-sweep response tests are conducted to investigate their vibration performances. The influence of different inclined corrugated angles, and fiber orientations on the natural frequencies, loss factors and the nominal Young’s modulus are plotted and discussed using validated numerical models. Meanwhile, the effect of Poisson’s ratio on the nominal Young’s modulus, natural frequencies and loss factors is also revealed explicitly. Furthermore, the comprehensive evaluation parameter that simultaneously characterizes the structural bearing capacity and vibration damping performance is further improved through parameter optimization.

Gel-type polymer electrolytes have received considerable attention due to the battery explosion issue associated with volatile liquid-electrolyte-based lithium ion batteries (LIBs). However, the high ionic conductivity of gel-type polymer electrolytes originates from polymer swelling by the liquid electrolyte, and these materials inevitably have poor mechanical strength during device deformation. Here, we report structural gel-type polymer separators with highly porous and uniform morphology arising from the phase inversion of PVdF-HFP polymers with highly dispersible nanoscale graphene oxide nanoflake (GON). Via simple γ-ray irradiation of conventional graphene oxide solution, large 2D particles were cut into small 2D particles with a narrow size distribution, which in turn resulted in a dramatic change in solution transparency and particle dispersity. γ-ray-irradiated graphene oxide nanoflakes (γ-GON) with high dispersity are located inside the porous PVdF-HFP skeleton, inducing additional micron-sized pores of ∼8 μm in the composite membranes. The modified porous film showed both gel-polymer electrolyte-like (uptake of 1.7 times more liquid electrolyte than conventional polyethylene separator) and polymer separator-like behavior (maintenance of original porous structure after soaked with liquid electrolyte). As a result, this pseudo-gel-polymer separator with a tailored pore structure has uniform ion flux and enhanced interfacial properties with electrodes, contributing superior battery performance.

It is of great significance to investigate effect of multiple heat treatments on fracture property of centrifugal casting stainless steels Z3CN20.09M cut from pump casing with long-term thermal aging degradation for nuclear power plants to consider actual operation of nuclear power plants. Both multiple heat treatments and accelerated thermal aging experiment at the same temperature of 400 °C for different time were successively carried out on centrifugal casting stainless steels Z3CN20.09M in order to examine the metallographic modification and impact properties. Finally, an additional investigation on the related fracture properties was carried out, in which the critical initial fracture toughness Ji was determined by stretch zone width and 0.2 mm offset line methods. These results indicated that the multiple heat treatments led to the dispersed distribution of ferrite phases in austenite matrix and thus microhardness increased, but impact energy exhibited a decreasing tendency significantly. After long-term aging, the metallographic structure remained almost unchanged, but the size of ferrite phases showed a slight increasing trend because of spinodal decomposition in ferrite phases and G-phase precipitation. In addition, centrifugal casting stainless steels Z3CN20.09M with multiple heat treatments exhibited the higher microhardness, Charpy impact toughness, critical initial fracture toughness JIC (J-integral determined by 0.2 mm offset line method), and JSZW (J-integral determined by stretch zone width method) than those with primary heat treatment, while the specific number of the heat treatment had a low influence on fracture toughness.

A split-ligand mediated re-precipitation (Split-LMRP) technique for colloidal perovskite quantum dots (QDs) was designed by separately dissolving rich oleic acid (OA) and amine ligands in the synthesis process. OA was used to control the polarity of the nucleation environment and was simultaneously employed as a stabilizer. The Split-LMRP technique allowed purification via the precipitation of QDs from a colloidal solution. The fabrication process is performed under ambient conditions, and the resulting CH3NH3PbX3 (X = Br, I) QDs exhibited strong photoluminescence (PL) emission with a maximum PL quantum yield of 91.5%. The size of the resulting perovskite QDs is tuned in the range of 2–5 nm by varying the ligand concentration and type of halide. We also investigated the charge-transport properties of the synthesized QDs using space-charge-limited current analysis and confirmed stable charge carrier mobility even when the QDs solution was spin-coated on a hydrophilic poly (3,4-ethylenedioxythiophene) polystyrene sulfonate film. Furthermore, the enhanced stability of CH3NH3PbX3 (X = Br, I) QDs improved the power conversion efficiency by the uniform surface passivation of the perovskite active layer which induces efficient exciton generation and charge transport.

We demonstrated a simple and effective processing protocol to improve the electrical conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films via post-treatment with an alcohol-based solvent, 2-chloroethanol (2-CE), and to enhance their performance as a transparent anode in organic photovoltaic cells (OPVs). Owing to its moderate boiling point, in contrast to previously reported chemicals, 2-CE is advantageous both for handling as a liquid-phase chemical and for drying from the films via evaporation. We compared the optical and electrical properties of the 2-CE-treated PEDOT:PSS with those of standard PEDOT:PSS-based electrodes with the addition of 5 vol% dimethyl sulfoxide (DMSO). With a similar thickness and transmittance in the visible region, the 2-CE-treated polymer electrodes outperformed the DMSO-added films with regard to the electrical conductivity (762 S cm−1 vs. 439 S cm−1). The work functions were almost identical: ∼5 eV. We fabricated and characterized organic photovoltaic devices using the anodes and polymer:fullerene blends and found that the 2-CE treatment resulted in higher device performance. Additionally, the 2-CE treatment was applicable to OPVs on a flexible plastic substrate, indicating the effectiveness of the proposed protocol.

To better understand the stress-corrosion behavior of friction stir welding (FSW), the effects of the microstructure on the stress-corrosion behavior of the FSW in a 2198-T34 aluminum alloy were investigated. The experimental results show that the low-angle grain boundary (LABs) of the stir zone (SZ) of FSW is significantly less than that of heated affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and parent materials (PM), but the grain boundary precipitates (GBPs) T1 (Al2CuLi) were less, which has a slight effect on the stress corrosion. The dislocation density in SZ was greater than that in other regions. The residual stress in SZ was +67 MPa, which is greater than that in the TMAZ. The residual stress in the HAZ and PM is −8 MPa and −32 MPa, respectively, and both compressive stresses. The corrosion potential in SZ is obviously less than that in other regions. However, micro-cracks were formed in the SZ at low strain rate, which indicates that the grain boundary characters and GBPs have no significant effect on the crack initiation in the stress-corrosion process of the AA2198-T34. Nevertheless, the residual tensile stress has significant effect on the crack initiation during the stress-corrosion process.

The effects of the alloying sequence and refining time on the inclusions in Fe–9Cr alloy reinforced with Y2O3 nanoparticles were investigated. The size and number of inclusions in the alloys were determined via optical microscopy, and their morphology and composition were determined via scanning electron microscopy. The Y2O3 mainly acted as a nucleating agent in the Si–Mn+Y2O3+Ti alloying process, promoting the precipitation of other oxides, which was beneficial for the formation of Y–Ti–O particles. In contrast, no Y–Ti inclusions were formed when the Si–Mn+Ti+Y2O3 alloying process was employed. In addition, the inclusions in the alloy tended to stabilize after refinement for 5–10 min. This study offers a general pathway for the manufacture of oxide dispersion strengthened steel via a smelting process.

The degradation of austenitic stainless steels under irradiation environment is a known problem for nuclear reactors, which starts from atoms displacement cascade. Here, molecular dynamics (MD) simulations have been used to investigate the formation of atomic displacement cascade in γ-iron for energies of the primary knock-on atom (PKA) up to 40 keV at 300 K. The number of Frenkel pairs increased sharply until a peak value was reached, which occurred at a time in the range of 0.1-2 ps. After that, a number of defects gradually decreased and became stabilized. Compared with α-iron, there was less defects in the stable stage, and more clustered defects were produced in γ-iron. Within the range of PKA energies, two regimes of power-law energy-dependence of the defect production were observed, which converge on 16.8 keV. The transition energy also marks the onset of the formation of large self-interstitial atom (SIA) clusters and vacancy clusters. Interstitial and vacancy clusters were in the form of Shockley, Frank dislocation loops and Stir-Rod dislocation loops.

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

The inherent optical and electrical properties of inorganic nanoparticles (NPs) give them high potential applicability in advanced energy devices. In this study, PEDOT:PSS was remodeled with aqueou...

Conventional and nanometer aggregate ZrO2-7wt.%Y2O3 ceramic powders taken as raw materials, plasma spraying and plasma spraying-laser remelting compound technology was used to prepare conventional and nanostructured thermal barrier coatings on the TiAl alloy surface. Effects of powder structure (feedstock) and laser remelting on organizational structure and phase of the coatings were analyzed using scanning electron microscope (SEM) and X-ray diffractometer (XRD). Results indicate that: conventional plasma sprayed ceramic coating presents typical lamellar stacking features; plasma sprayed nanostructured coating consists of fully melted region and partially melted region, presenting a two-phase structure. Under the comprehensive impacts of laser power, energy density, temperature field distribution in the laser action region, ceramic heat conductivity coefficient and coating thickness and other factors, the coating presents obvious lamellar structural features after laser remelting; the upper part is compact columnar crystal remelting region and the lower part is residual plasma spraying region. Due to toughening effect of residual nanoparticles in the remelting region of laser remelted nanostructured coating, grain-boundary strength is high and there are a considerable number of transgranular fractures, but the fractures in the remelting region of laser remelted conventional coating are basically intergranular fractures. Conventional plasma sprayed ceramic coating is mainly of tetragonal phase together with a small quantity of monoclinic phases, but nanometer plasma sprayed ceramic coating only has non-equilibrium tetragonal phases. After laser remelting, both conventional coating and nanometer coating mainly have non-equilibrium tetragonal phases with a small quantity of cubic phases.

Current tissue engineering strategies through scaffold-based approaches fail to recapitulate the complex three-dimensional microarchitecture and biochemical composition of the native Annulus Fibrosus tissue. Considering limited access to healthy annulus fibrosus cells from patients, this study explored the potential of bone marrow stromal cells (BMSC) to fabricate a scaffold-free multilamellar annulus fibrosus-like tissue by integrating micropatterning technologies into multi-layered BMSC engineering. BMSC sheet with cells and collagen fibres aligned at ~30° with respect to their longitudinal dimension were developed on a microgroove-patterned PDMS substrate. Two sheets were then stacked together in alternating directions to form an angle-ply bilayer tissue, which was rolled up, sliced to form a multi-lamellar angle-ply tissue and cultured in a customized medium. The development of the annulus fibrosus-like tissue was further characterized by histological, gene expression and microscopic and mechanical analysis. We demonstrated that the engineered annulus fibrosus-like tissue with aligned BMSC sheet showed parallel collagen fibrils, biochemical composition and microstructures that resemble the native disk. Furthermore, aligned cell sheet showed enhanced expression of annulus fibrosus associated extracellular matrix markers and higher mechanical strength than that of the non-aligned cell sheet. The present study provides a new strategy in annulus fibrosus tissue engineering methodology to develop a scaffold-free annulus fibrosus-like tissue that resembles the microarchitecture and biochemical attributes of a native tissue. This can potentially lead to a promising avenue for advancing BMSC-mediated annulus fibrosus regeneration towards future clinical applications.

With the development of nanomanufacturing methods, the manipulation of photons down to the nanoscale in silicon integrated optical chips has become a feasible and promising solution for next-generation data processing as electronic chips reach their limit. As an essential active device that generates photons for all other working photonic components, silicon lasers are the last barrier to achieve silicon integrated optical chips. Although optical gain in silicon nanocrystals (Si–NCs) was observed in 2000, the progress in realizing all-Si lasers has been very limited due to the inferior optical gain compared to traditional gain materials. In this paper, highly luminescent thin films of Si–NCs with a photoluminescence quantum yield of 57% are developed. The broadband photoluminescence covers the wavelength range from 650 to 900 nm, and wide-range optical gains are identified, indicating the feasibility of a tunable laser. Distributed feedback (DFB) all-Si lasers are fabricated using these thin films and pumped by femtosecond pulses. Various characteristic lasing behaviors are observed. Additionally, three different DFB grating periods are selected, and the lasing peak can be tuned by over 100 nm. The lasing thresholds range from 8.3 to 53.3 MW/cm2. The linewidths of lasing peaks are less than 2 nm.

An electron-rich fused indoloindole-based poly(indoloindole-selenophene vinylene selenophene) was synthesized and characterized. Soxhlet can be obtained by continuously purifying the product with a specific solvent and obtaining a pure polymer with a high concentration. Molecular weight is affected by the vapor pressure of marginal solvent, and the polymer was fractionated using tetrahydrofuran, chloroform, and chlorobenzene. Solubility is closely related to the morphology of bulk heterojunction and device parameters. In the solution process of fabricating the organic solar cell, securement of solubility has a great effect on the performance of the device, because morphology and orientation of a photo-active layer which significantly affect charge transport in the device. Since tetrahydrofuran (THF) Soxhlet solvents have high vapor pressure and appropriate solubility parameters, THF induced the best solubility of P-IDI-SVS materials for organic solvents. And through additive optimization, the performance of the device based on P-IDI-SVS from THF-Soxhlet extraction was enhanced. This is expected to be a meaningful study because the effect on solubility of Soxhlet solvent suggests factors to be considered in the solution process in organic solar cell research. In addition, surface modified bulk heterojunction was observed using atomic force microscopy, photoluminescence, time-correlated single photon counting and Raman spectroscopy analysis.

Phototheranostics has attracted great interest in cancer therapy. Small-molecule self-reporting photosensitizers, one kind of idea agent in phototheranostics, enables simultaneous photodynamic therapy (PDT) and feedback of therapeutic efficacy. However, previous such photosensitizers exclusively employed the change of single emission to monitor cell death, which can be disturbed by variations in photosensitizer concentration and the excitation intensity. Herein, we report a unique self-reporting photosensitizer TPA-3PyA+ constructed from a twisted triphenylamine unit (TPA), three benzene ring units and three cyanovinyl-pyridinium units (PyA) for PDT and its real-time monitoring in a dynamic dual-color mode. TPA-3PyA+ possesses a rotatable electron donor-π bridge-electron acceptor framework and exhibits high singlet oxygen quantum yield (124%) and a twisted intramolecular charge transfer (TICT) effect. TPA-3PyA+ not only enables effective staining of cancer cells with dual-color fluorescence due to the TICT effect but also shows excellent PDT performance. The simultaneous change in emission color, intensity and intracellular location of TPA-3PyA+ during cell death allows it to self-report cell death. Moreover, the change of dual-emission color allows distinguishing living and dead cells and effectively avoids interference in previous single-emission self-reporting photosensitizers. This work highlights the great potential of a self-reporting photosensitizer with dual-color emissions for efficient feedback of theranostics.

Polyvinyl carbazole (P0)-based pendant polymers were synthesized by modifying carbazole motifs with pyrene derivatives (P1 and P4) to manipulate the bandgap and frontier orbital energy levels. To establish the electronic properties of pendant polymers according to structural differences, the polymers were utilized as additional hole transport layers in planar-type perovskite solar cells and organic photovoltaic cells. When P4 with thiophene-pyrene pendant was used as hole transport layer, all device parameters, except open-circuit voltage, were significantly improved in comparison with P0 and P1 (conjugated with t-butyl pyrene derivatives). Since P4 had more electrically conductive thiophene units than benzene units with fewer alkyl groups, the supramolecular assembly of P4 was found to be more favorable in electronic devices. Furthermore, devices with P4 demonstrated lower dark current than others, which could potentially be useful for charge carrier transport and sensitive photo detecting devices.

A novel controlled drug release system based on pH sensitive polyacrylonitrile (PAN) nanoflowers in different kinds of solvents was successfully prepared with azobisisobutyronitrile (AIBN) as the initiator and without any emulsifier or stabilizer by a one step static polymerization method. The composition and structure of the PAN nanoflowers were analyzed by FTIR, XRD, SEM, TEM, and laser particle size analysis. The polymer particles consisted of a number of lamellae, with a sheet thickness of about 10 nm, and were similar to the shape of flowers with a particle diameter of about 350 nm. The mechanism of the polymerization reaction and the formation were studied. Moreover, the effects of monomer ratio, initiator concentration, reaction time, dispersion medium and co-monomer on the morphology and particle size of the nanoflowers were also discussed. A relatively large specific surface area was formed during the formation of the nanoflowers, which favored drug adsorption. The results of the in vitro experiments revealed that PAN(TBP) nanoflowers, containing BSA in buffer solution of pH 7.4, demonstrated good sustained-release and the cumulative release rate was about 83% after 260 h. The results also showed that the sustained-release from the PAN(TBP) nanoflowers best fitted the Riger-Peppas model. This study indicated that PAN(TBP) nanoflowers provided a theoretical base for the development of carriers for sustainable drug-release.

Two-dimensional (2D) molybdenum diselenide (MoSe2) as one of the ultrathin transition metal dichalcogenides (TMDs) has attracted considerable attention because of its potential applications in thermoelectric and nano-electronic devices. Here, the thermal conductivity of monolayer MoSe2 and its responses to simulated size and defects are studied by nonequilibrium molecular dynamics simulations. With the increase of sample length, the thermal conductivity of monolayer MoSe2 nanoribbons exhibits an enhancement whereas it is insensitive to the width. At room temperature, the thermal conductivities of monolayer MoSe2 along armchair and zigzag directions are 17.758 and 18.932 W (m K)−1, respectively, which are consistent with previous results. The impact of defects on thermal conductivity has also been studied by varying the concentration of the vacancy from 0.1% to 0.5%. The results show that an increase of the defect concentration will greatly suppress the thermal conductivity. The 0.5% defect concentration with a Mo vacancy can result in a thermal conductivity reduction of ∼43%. Such a study would provide a good insight into the tunable thermal transport for potential applications of not only monolayer MoSe2, but also many other TMDs.

Enlightened by face-centered cubic crystal structure, an ultra-lightweight composite sandwich panel with face-centered cubic core (CSPFCC) is proposed, which demonstrates excellent broadban...

6061 aluminium was treated by Plasma electrolytic oxidation (PEO) where a new experimental method was introduced: the applied voltage of the PEO process was quickly increased to 486 V by different ...

Embedding of optical fiber sensors into materials to detect and monitor the deformation and damage of structures has attracted much attention recently. However, the embedding of optical fiber sensors into metallic materials is usually difficult due to lack of suitable technique, which does not damage the optical fiber during metal processing. In this paper, we introduced a very high-power ultrasonic additive manufacturing (UAM) for producing metallic structure optical fiber sensors. Single-mode optical fibers (SMFs) were successfully embedded in aluminum (Al 1100) matrix by this technique. Tensile strain experiments were performed by a fiber optical white-light interferometric sensing system, and the effect of consolidation contact pressure of UAM on the output strain-applied strain relation was examined systematically. As the appropriate contact pressure of 1300-1350 N was taken, and the excellent and reliable out strain-applied strain relations were obtained. These results demonstrate that the UAM produced optical sensor like a “nervous system” is capable of monitoring the health condition of metallic structural device.

A simple and compact cascade fiber optic sensor for simultaneous measurement of temperature and strain is proposed and demonstrated in this letter. The structure consists of a short section of a PANDA fiber and a cascaded fiber Bragg grating (FBG). A Sagnac interferometer was formed in the PANDA fiber by tip coating the gold film. The sensitivities of the PANDA fiber and FBG for the temperature and strain are different, which makes the sensor to have the ability to measure strain and temperature simultaneously. Experimental results show that the maximum errors for the temperature and strain measurements are 0.22 °C and 21.7 μϵ , respectively. Based on its simple fabrication process and compact size, the sensor described in this letter could be a competitive candidate in remote sensing for the simultaneous measurement of temperature and strain.

We demonstrate InP-based buried grating coupled surface-emitting distributed feedback (DFB) lasers designed to operate at a wavelength of 2004 nm. The laser structure consists of three InGaAsSb/InGaAs QWs, with a 5 $\mu \text{m}$ wide double-channel ridge waveguide. A second-order semiconductor/semiconductor grating is used for in-plane feedback and vertical out-coupling. The single longitudinal mode emission wavelength of the fabricated laser can be adjusted from 2002.7 to 2006 nm without any mode hopping. High side-mode suppression ratio (SMSR) of at least 35 dB is achieved under all injection currents and temperature conditions. The edge output power reaches 19 mW, measured in continuous-wave (CW) mode at 10 °C. Simultaneously, the output power of surface emission reaches 8 mW.

Various plasma electrolytic oxidation (PEO) ceramic coatings were fabricated on aluminum in the electrolytes with different concentrations of Na2SiO3·9H2O. The morphology of fractured cross-section and coating/substrate (C/S) interface, phase compositions, and corrosion behavior of these ceramic coatings were characterized employing field emission scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results showed that adding Na2SiO3·9H2O in the electrolyte could reduce the decrease amplitude of the voltage-time curve, and it can affect the types of the anodic film before the beginning of plasma discharges. A novel phenomenon was recorded as PEO treatment was carried out in the electrolyte with 1.85 g l−1 Na2SiO3·9H2O that the substrate was first covered by a barrier-type anodic film, and then a porous-type anodic film appeared after the barrier-type anodic film was broken down. The anodic film continued to grow for a long duration in the PEO process after being broken down. Characteristics of PEO ceramic coatings with a similar thickness acquired in various electrolytes were also evaluated. XRD results indicated that these ceramic coatings of similar thickness were mainly composed of α-Al2O3 and γ-Al2O3, and the α-Al2O3 proportion decreased with increasing Na2SiO3·9H2O concentration. The electrochemical data showed that the corrosion resistance of these PEO ceramic coatings of similar thickness decreased by adding Na2SiO3·9H2O in the electrolyte.

Plasma electrolytic oxidation (PEO) of Al was carried out in dilute alkaline sodium tripolyphosphate (Na5P3O10) electrolyte. Surface and cross-section morphologies, elemental and phase compositions were characterized by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and X-ray diffractometer (XRD). The results revealed that a severe thinning of the anodic film resulted in the voltage decrease at the initial stage of the PEO process. Porous-type anodic film with uniform pore diameter were fabricated at the initial stage of PEO process. Subsequently, detachments and cracks took place on the anodic films, and served as weak regions occurring dielectric breakdown preferentially due to the concentration of electric current at these sites. Two origins of PEO coatings, the transformation of anodic films and the normal generation of PEO coatings through the plasma discharges, were proposed. The results also indicated that P element mainly participated in the anodic oxidation and existed as amorphous phase in the inner side areas of anodic films except the barrier layer. Based on the analyses of the microstructure evolution and the chemical composition, a schematic of coating growth mechanism was proposed in the end.