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Ultraviolet (UV) detector based on β-Ga2O3/p-GaN was fabricated in this paper. The growth process involved deposition of amorphous Ga2O3 layer by means of magnetron sputtering and conversion of β-Ga2O3. The obtained detector displays excellent UV sensing properties which covers Ultraviolet A(UVA)/Ultraviolet C(UVC) region with fast response. It will provide a new route to fabricate β-Ga2O3/p-GaN heterostructure for applications in broadband ultraviolet sensing.

The formation mechanisms for two carbides with co-existence and increasing stacking faults nearby the carbides during surfacing welding were investigated in this study. The results indicated that the surfacing layer had a two-phase structure of a matrix phase and a second phase, the density of the second phase was relatively small and the second phase was discontinuous, by contrast with the as-received welding wire. Relatively uniform microstructure of surfacing layer and the welding interface without melting of base metal were obtained, resulting in an inapparent change in the microhardness. A few carbides with blocky shape were identified in the surfacing layer. The mechanisms for (Cr,Co)23C6 of face-centered cubic crystal structure co-existing with (Cr,Co)7C3 of hexagonal close-packed crystal structure and (Cr,Co)23C6 subsequently forming close to the pre-formed (Cr,Co)7C3 during the cooling process were discussed in alloying element, calculated equilibrium phase diagram, Gibbs energy, etc. The relatively higher density of the stacking fault present around the carbides was understood from forming energy of stacking faults.

As a promising anode material candidate for sodium-ion batteries, antimony (Sb) has attracted enormous research interest due to its high specific capacity and low sodiation voltage. However, its dramatic volume expansion upon sodiation adversely affects its cycle stability. We have developed an oxidation-coating-reduction strategy for fabricating yolk-shell Sb@C rods from commercially available Sb powder. In particular, the thermal reduction of vaporized Sb2O3 generates densely distributed Sb single atoms and clusters on the carbon shell. The sodiation process of the Sb@C sample was recorded through in situ transmission electron microscopy. Irregular expansion of Sb particles was observed, and it was also revealed that the carbon shell could deform with the expanded Sb particles. Beyond the intuitively understood advantage that internal voids can provide space for expansion of internal active materials, the deformability of carbon shells can add further ability to withstand the volume expansion. The two structural merits of the yolk-shell construction enable the Sb@C material to deliver an enhanced cycle performance. Its reversible capacity exceeds 620 mA h g−1 at 0.1 C, with an initial coulombic efficiency of up to 84.9%, and about 95% of the capacity in the charging voltage profile is delivered below 1.0 V vs. Na+/Na. These performance metrics are very promising for potential practical applications.

Molybdenum is a newly added material in additive manufacturing material cabinet, and it is under the spotlight owing to its crucial applications. The high-energy electron beam selective melting (EBSM) process is supposed to be a promising technique for molybdenum printing because of its vacuum environment. This paper presents EBSM numerical process simulation for molybdenum on macro- and mesoscale established with exclusive powder material modeling. Experimentally determined, process parameters are implemented in 3D macro- and 2D mesoscale models for a profound process insight. Primarily molybdenum powder material model is established, and a multi-track FEM simulation is performed to predict melt pool configuration, temperature field and phase transformation. Next, powder consolidation mechanism, side surface roughness, porosity, and voids are investigated through a CFD model, where the molybdenum particles are explicitly considered from the EBSM process viewpoint. Results proved the effectiveness of the numerical simulation for detailed EBSM process understanding for molybdenum material.

The combination of graphene oxide (GO) and iron oxide (Fe2O3) may induce property enforcement and application extension. Herein, GO/Fe2O3 nanocomposites were synthesized via the vacuum-freeze-drying method and used for the thermal decomposition of ammonium perchlorate (AP). A series of characterization techniques were applied to elucidate the as-obtained nanomaterial's physicochemical properties. These results show that the treated GO is consistent with the pristine GO after the freeze-drying treatment. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses show that iron oxide nanoparticles are anchored on and between the GO sheets. The catalytical effect investigation on AP with different Fe2O3: GO ratios indicates that the high-temperature decomposition temperature of AP could be decreased by a temperature as high as 77 °C compared to pure AP accompanied by 3 wt % GO/Fe2O3 nanocomposite which proves the high catalytic performance of the nanocomposites. The first-principles calculation was employed to elaborate the synergistic effect, and the findings demonstrate that the presence of graphene in the catalyst can enhance the catalytic effect via reducing the activation energy barrier by ∼17% in the reaction of AP thermal decomposition.

The electrolytic reduction of TiO2 in LiCl–Li2O (1 wt.%) at 650 °C was investigated under a series of cathodic reduction potentials and applied charges to provide a mechanistic understanding of the electrochemical characteristics of the system. The optimal cathodic reduction potential was determined as being −0.3 V vs. Li/Li+. Li2TiO3 and LiTiO2 were structurally identified as intermediate and partial reduction products of the TiO2 electrolytic reduction. The reduction of LiTiO2 was extremely slow and reversible due to its high stability and the detrimental effect of Li2O accumulation within the solid particles. The most reduced product obtained in this study was LiTiO2, which was achieved when using 150% of the theoretical charge under the optimal reduction potential. The highest reduction extent obtained in this study was 25%. Based on theoretical DFT modeling, a detailed multistep reduction mechanism and scheme were proposed for TiO2 electrolytic reduction in LiCl–Li2O (1 wt.%) at 650 °C.

The electrodeposition of Al was investigated in an ionic liquid (IL), with 1-ethyl-3-methylimidazolium tetrachloroaluminate ([EMIm]AlCl4) as the electrolyte with AlCl3 precursor. The [EMIm]AlCl4 electrolyte exhibited a wide and stable electrochemical window from 3.2 to 2.3 V on a glassy carbon electrode when temperature was increased from 30 °C to 110 °C. The addition of AlCl3 into [EMIm]AlCl4 generated significant well-developed nucleation growth loops, and new coupled reduction and oxidation peaks in cyclic voltammograms corresponding to the Al deposition and dissolution, respectively. A calculation model was proposed predicting compositions of anions in AlCl3/[EMIm]AlCl4 system, and [Al2Cl7]− was found to be the active species for Al deposition. In AlCl3/[EMIm]AlCl4 (1:5), the reduction rate constants were 1.18 × 10−5 cm s−1 and 3.37 × 10−4 cm s−1 at 30 °C and 110 °C, respectively. Scanning electron microscope (SEM), energy dispersive spectroscope (EDS), and X-ray diffraction (XRD) microscope results showed that the metallic Al film had been successfully deposited on glassy carbon electrodes through constant-potential cathodic reductions. The [EMIm]AlCl4 was a promising electrolyte directly used for Al deposition.

Powder bed fusion (PBF) process is expeditely moving towards its maturity for the direct manufacturing of intricated and sophisticated metallic parts. The typical process is instead complex and yet challenging to interpret experimentally. Modeling and simulation strategy has been widely implemented to comprehend and optimize the process. Therefore, an integrated simulation approach incorporating stochastic powder deposition and subsequently selective melting is developed to understand the consolidation mechanism in a multilayer process of electron beam PBF additive manufacturing. Simulation results of a thin-walled cross section are validated with the published experimental data to demonstrate the effectiveness of the proposed model. The simulation results of the multilayer process revealed that the layer thickness keeps on slight changes until reaching a steady state during the multilayer additive process. The stable powder layer thickness is systematically analyzed, which proved that the influence of the wall effect should be considered in smaller nominal layer thickness and denser powder bed. Finally, the printing quality in the multilayer process is dependent on adequate inter- and intra-layer bonding when the layer thickness reaches its maximum value, where agglomeration and balling effect in melt pool dynamics predominant by surface tension play crucial roles.

Modeling and simulation in meso-scale have been used to investigate the complicated physics involving powder behaviors during the forming process in electron beam selective melting. But it is difficult to quantitatively predict the forming quality of parts due to the huge calculation amount for multi-layer and multi-pass cases. In this paper, we presented a novel frame for investigating the side surface roughness of fabricated components based on single-track simulation. An integrated model of selective beam melting with considering the random distribution powder particles was developed. The surface morphologies of simulated tracks were used to calculated the surface roughness, and the calculated results were validated by experiment data from independent literature. The effects of heat input were discussed in detail. It reveals that the side roughness increases with a lower heat input. The mechanism behind is the fluctuation of tracks induced by the asymmetry of molten pool, which is related to the coalescence of melting particles and unevenness of powder distribution.

The exploration of new highly efficient and durable for the oxidation of amines to imines has gained immense attention. In this work, a new polyoxometalate-based metal–organic framework (POMOF) {Cu4(C26H16N4O4)4(CH3CN)2[SiW12O40]}·4H2O (SiW-Cu-DPNDI) was constructed with a catalytic oxidant Keggin-type [SiW12O40]4− anion, a photosensitizer N,N'-bis(4-pyridylmethyl)naphthalene diimide (DPNDI) ligand, and a Cu(I) cation via self-assembling. Although single-crystal X-ray diffraction, power X-ray diffraction (PXRD), infrared (IR) spectroscopy, etc., were employed to confirm the hierarchical structure of SiW-Cu-DPNDI, critical analyses through, such as the magnetic susceptibility measurements, the Mott–Schottky measurements, and the electron spin resonance studies were successfully applied to elucidate the properties of POMOF. SiW-Cu-DPNDI was highly active in the heterogeneous photocatalysis of the oxidation of amines to imines under mild conditions. Additionally, this catalyst exhibited high stability and reusability without losing its activity during the photocatalysis. The possible mechanism of the oxidation coupling was extensively investigated under visible-light (Vis)-irradiation.

By maintaining high piezoelectric coefficients (d33), increasing the depolarization temperature is the key to constructing high-performance high-temperature piezoceramics. Unfortunately, so far, no piezoceramic has been found that still has a d33 value above 700 pC N−1 by in situ testing at a high-temperature of 400 °C. For popular 0.36BiScO3-0.64PbTiO3 ceramics with a MPB structure, the in situ quasi-static d33 value at 400 °C is only 405 pC N−1. Herein, a new strategy to enhance perovskite lattice distortion to obtain oxides with excellent high-temperature piezoelectricity has been proposed. By introducing Bi(Zn0.5Hf0.5)O3 to enhance lattice distortion of a (1 − x)BiScO3-xPbTiO3 matrix, a ternary system zBiScO3-xPbTiO3-yBi(Zn0.5Hf0.5)O3 (zBS-xPT-yBZH) was designed. A record-high in situ quasi-static d33 value of 726 pC N−1 at 400 °C is achieved in a 0.355BS-0.635PT-0.01BZH composition. Structural analysis confirmed that the introduction of highly tetragonal Bi(Zn0.5Hf0.5)O3 can enhance the lattice distortion and the sample annealed at 400 °C still maintains a stable domain configuration. Moreover, a high-temperature piezoelectric energy harvester is manufactured from the optimal material, and exhibits excellent high-temperature power generation capacity, and a 10 μF commercial electrolytic capacitor can be easily charged to 0.9 V in 40 s at 400 °C. This work demonstrates that zBS-xPT-yBZH ceramics have great potential for application in extreme high temperature environments, and pave the way for obtaining high-quality high-temperature piezoelectric materials.

The self-assembly of plasmonic nanoparticles into highly ordered superlattices could pave the way toward novel nanomaterials for surface-enhanced Raman scattering (SERS). Here, we propose the formation of large-area superlattices of elongated rhombic dodecahedra in a vertical orientation via a controlled droplet evaporation process. Expectedly, the constant humidity of the experimental condition could control the evaporation speed of droplets and this procedure promotes the balance between driven depletion attraction and electrostatic repulsion in the system, leading to the generation of well-organized three-dimensional (3D) superlattices. The unique geometry of elongated rhombic dodecahedra could establish the tetragonal superlattices, which breaks the conventional hexagonal symmetry of gold nanorods. Specifically, the influence of the type and concentration of surfactants, the concentration of nanoparticles, and the amount of droplets on the preparation results were systematically investigated to find the optimal assembly parameters. Remarkably, such close-packed tetragonal arrays of vertically aligned elongated rhombic dodecahedra exhibit more excellent SERS performance compared with the traditional hexagonal superstructure of gold nanorods. Benefiting from the high sensitivity and reproducibility of elongated rhombic dodecahedron superlattices, their applications in the determination of pesticide residues in apple and grape peels were successfully demonstrated. As a result, this study may advance the production of innovative plasmonic nanomaterials for a broad range of fields.

In this article, ultra-broadband photoluminescence in near-infrared is achieved in KZnF3 glass ceramics doped with Er3+and Ni2+ ions. Er3+-Ni2+ co-doped fluorosilicate glass and glass ceramics embedded with perovskite nanocrystals were fabricated and efficient energy transfer (ET) from Er3+ to Ni2+ ions was confirmed by luminescence spectra and decay curves. In the glass ceramic samples, Ni2+ ions were effectively sensitized by Er3+, and ultra-broadband photoluminescence from 1400 to 2300 nm was observed when a 980 nm laser was used as a pump, as shown in Fig. 1. The temperature and humidity stability of the glass ceramic samples was characterized from the measured transmittance. These results demonstrated that Ni2+-Er3+ co-doped glass ceramics have significant potential for application in optical communication and broadband amplifiers.

Monitoring the dynamic humidity requires sensors with fast response and anti-electromagnetic interference, especially for human respiration. Here, an ultrafast fiber-optic breath sensor based on the humidity-sensitive characteristics of gelatin film is proposed and experimentally demonstrated. The sensor consists of a microknot resonator superimposed on a Mach-Zehnder (MZ) interferometer produced by a tapered single-mode fiber, which has an ultrafast response (84 ms) and recovery time (29 ms) and a large dynamic transmission range. The humidity in dynamic ambient causes changes in the refractive index of gelatin coating, which could trigger spectral intensity transients that can be explicitly distinguished between the two states. The sensing principle is analyzed using the traditional transfer-matrix analysis method. The influence of coating thickness on the sensor's trigger threshold is further investigated. Experiments on monitoring breath patterns indicate that the proposed breath sensor has high repeatability, reliability, and validity, which enable many other potential applications such as food processing, health monitoring, and other biomedical applications.

Graphene and carbon nanotube (CNT) are representative carbon nanomaterials which have aroused numerous research interest due to their extraordinary material properties and promising application potentials, especially in the energy storage and conversion areas. However, the agglomeration happening in these materials has largely blocked their applications. Hybridization of CNT with graphene can, on one hand, prevent the agglomeration behavior, on the other hand, generate a synergistic effect between them with enhanced physical and chemical properties. There have been many studies conducted to find out the suitable approaches to synthesize graphene/CNT composites, and realize the application potentials of these structures. Based on the recent advances, this paper reviews the current research progress that has been achieved in synthesizing graphene/CNT composites, and the energy-related applications. Through this review, we aim at stimulating more significant research on this subject.

Constrained groove pressing (CGP) process is a severe plastic deformation (SPD) method that can create ultrafine-grained microstructure in the sheet metals. In this study, residual stresses of the CGP process and the effect of the friction coefficient on the residual stresses were investigated. The residual stresses were measured in two directions using a multi-cut contour method and a mathematical-finite element model was developed to estimate the uncertainty of results of the multi-cut contour method. In order to study the effect of the friction coefficient on the residual stresses, a 3D finite element model was employed and the results of it were validated with the experimental results of the CGP process. According to the results, residual stresses in the first pass of CGP are compressive on the surface and gradually change to tension at the center of the thickness. Investigation of the effect of the first cut on the residual stresses and uncertainty of the second cutting plane showed that the effect of the first cut is only confined to regions near the intersection of the two cuts. Distancing from the intersection of two cuts causes the effect of the first cut to be ineffective on the second cut. Also, evaluation of the effect of friction coefficient on the residual stress illustrated that friction has a direct relationship with the residual stresses.

Microstructure and mechanical properties of 6061-T6 aluminum alloy/304 stainless steel (Al/steel) joints welded by inertia friction (IFW) and continuous drive friction (CDFW) were studied comparatively. Morphology, microstructure, interfacial composition, and mechanical properties of Al/steel joints were investigated. Results showed that an intermetallic compound (IMC) reaction layer was formed at the welding interface in the CDFWed joint, and wider and clearer than that of the IFWed joint. The high concentration Si was observed at the welding interface. The grain of fully dynamic recrystallized zone (FDRZ) was below 0.1 μm in both joints, and the average width of FDRZ in the IFWed joint and CDFWed joint was about 5 μm and 2 μm, respectively. FDRZ had the high hardness, and the hardness value of IFWed joint was higher than that of CDFWed joint. The maximum tensile strength of IFWed joint was higher than that of CDFWed joint, and the reason should be related to the thickness of IMC at the welding interface.

Electron beam melting (EBM®) is a metallic printing process that has become increasingly sophisticated over the past decade. The formation of residual stress due to a high-energy electron beam is considered a primary hindrance in the maturation of the process itself and, subsequently, the quality of the printed parts. Contrary to hit and trial, the finite element method (FEM) has become a prevalent technique for estimating residual stresses and subsequent distortion in additive manufacturing chunks. Since the EBM® is a powder bed fusion (PBF) process, powder material properties are substantially different from those of solid and undoubtedly important for efficient simulation. Several reviews have been published on FEM applications in additive manufacturing so far; however, a straightforward solution for material modeling from EBM® viewpoint is still needed. This critical review paper is an attempt to propose a material modeling approach to establish an adequate FEM model for EBM® process simulation.

Ho3+ doped and Ho3+/Tm3+ co-doped fluoroindate glass samples were prepared and their emission properties were compared. Under 888 nm laser excitation, the emission at 2 μm of Ho3+ ions with co-doping 2 mol% Tm3+ ions had a 2.9-fold improvement compared with that of Ho3+ doped. The absorption and emission spectra, and energy level lifetime of Ho3+/Tm3+ co-doped glass samples were measured to analyze the energy transfer processes and enhancement mechanisms. The luminescence intensity at 2 μm can be greatly increased due to the bidirectional energy transfer between Tm3+ and Ho3+ ions.

The continuous drive friction welding of aluminum alloy to stainless steel was investigated in this paper. Microstructural characterization, intermetallic compound (IMC), and mechanical properties of the friction welded Al/Fe joint were studied. Results showed that thermal mechanically affected zone (TMAZ) at the Al side was subjected to both thermal cycling and mechanical force, and grain size was 1–3 μm, and streamlines were more dramatically than at the steel side. In fully dynamic recrystallized 127 zone (FDRZ), microstructure became the fine equiaxed grains, and its width at the steel side was about 5 μm. The local Si enrichment IMC layer was formed at the interface area of Al/Fe joint, and its average thickness was about 300 nm. IMC layer was relatively flat at the steel side, while uneven at the Al side. The hardness reached to the maximum value (395.8 HV) at the steel side in FDRZ, and the average hardness was only 76 HV in heat-affected zone (HAZ) at the Al side. When forge pressure was below 220 MPa, the tensile strength of joint was approximately linearly related to the forge pressure.

In this study, the multifunctional carbon nitride based composite graphitic-C3N4 (g-C3N4)/TiO2/Ag was prepared through a simple and efficient vacuum freeze-drying route. TiO2 and Ag nanoparticles were demonstrated to decorate onto the surface of g-C3N4 sheet. In the ultraviolet–visible absorption test, a narrower band gap and red-shift of light absorption edge were observed for g-C3N4/TiO2/Ag compared to pristine g-C3N4 and single-component modified g-C3N4/TiO2. The photodegradation property of g-C3N4/TiO2/Ag was investigated toward the degradation of methylene blue (abbreviated as MB) under the irradiation of visible light. These results indicated that the degradation performance of organic dyes for g-C3N4/TiO2/Ag was obviously improved compared with g-C3N4/TiO2 and g-C3N4. The reaction rate constant of MB degradation for g-C3N4/TiO2/Ag was 4.24 times higher than that of pristine g-C3N4. In addition, such rationally constructed nanocomposite presented evidently enhanced antibacterial performance against the Gram-negative Escherichia coli. Concentration dependent antibacterial performance was systematically investigated. And 84% bacterial cell viability loss had been observed at 500 μg/mL g-C3N4/TiO2/Ag within 2 h visible light irradiation.

peer-reviewed Up-conversion luminescence and C-band microsphere laser output is reported for an Er3+-doped ZrF4-BaF2-YF3-AlF3 (ZBYA) fluorozirconate glass microsphere. The microsphere was fabricated by heating a ZBYA glass filament using a CO2 laser beam. The fabrication process accurately and repeatably produces microspheres of 68 μm diameter. The input and output laser light was coupled to the microsphere using a tapered optical fiber. The coupling position between the tapered fiber and microsphere was adjusted using a sophisticated three-dimensional translation stage. The up-conversion luminescence emission, single-mode and multi-mode laser at C-band (1530 to 1565 nm) were observed when pumped using a 980 nm laser.

Improving the operating characteristics of piezoelectric devices in high temperature environments urgently requires the development of piezoceramics with both high piezoelectric coefficient and excellent temperature stability. However, it is difficult for existing piezoceramics to take care of both at the same time. Generally, high piezoelectricity can be obtained at morphotropic phase boundary (MPB) in the binary systems, such as PbZrO3–PbTiO3 and Pb(Mg1/3Nb2/3)O3–PbTiO3, but the temperature stability is unsatisfactory, which seriously restricts the practical application. Here, an optimum composition having excellent comprehensive properties is constructed by designing multiple MPBs in the novel xPb(In1/2Nb1/2)O3-yBiScO3–zPbTiO3 ternary system. When x = 0.04, y = 0.345 and z = 0.615, the specimen has a high piezoelectric coefficient d33 of 478 pC/N at 200 °C, meanwhile, the fluctuation of d33 is less than ± 10% over an ultra-broad temperature range of 50–350 °C. Combined with a variety of in situ analysis techniques, it can be determined that the temperature-insensitive high piezoelectric coefficient is related to the multiple MPBs design, which is beneficial to the optimization of the hierarchical domain configuration. The developed phase boundary design strategy paves a new way to building next generation high performance high temperature piezoceramics.

Ho3+ and Nd3+/Ho3+ doped fluoroaluminate glass samples were fabricated by the melt-quenching method and showed high transmittance and a wide transparency window. Under 808 nm pumping, emission at 3.9 µm, corresponding to the Ho: 5I5→5I6 transition, was observed. The presence of Nd3+ strongly enhances the Ho3+ emission. The emission and absorption cross-sections were calculated using the Judd-Ofelt, Füchtbauer-Ladenburg and McCumber theories and the energy transfer mechanism between Nd3+ and Ho3+ was analyzed. The most efficient 3.9 µm emission was obtained when the concentration ratio of Nd3+: Ho3+ is 1:2.

Unraveling the complex, competing pathways that can govern reactions in multicomponent systems is an experimental and technical challenge. We outline and apply a novel analytical toolkit that fully leverages the synchronicity of multimodal experiments to deconvolute causal from correlative relationships and resolve structural and chemical changes in complex materials. Here, simultaneous multimodal measurements combined diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and angular dispersive X-ray scattering suitable for pair distribution function (PDF), X-ray diffraction (XRD) and small angle X-ray scattering (SAXS) analyses. The multimodal experimental data was interpreted via multi-level analysis; conventional analyses of each data series were integrated through meta-analysis involving non-negative matrix factorization (NMF) as a dimensional reduction algorithm and correlation analysis. We apply this toolkit to build a cohesive mechanistic picture of the pathways governing silver nanoparticle formation in zeolite A (LTA), which is key to designing catalytic and separations-based applications. For this Ag-LTA system, the mechanisms of zeolite dehydration, framework flexing, ion reduction, and cluster and nanoparticle formation and transport through the zeolite are elucidated. We note that the advanced analytical approach outline here can be applied generally to multimodal experiments, to take full advantage of the efficiencies and self-consistencies in understanding complex materials and go beyond what can be achieved by conventional approaches to data analysis., Chemical Science, 12 (41), ISSN:2041-6520, ISSN:2041-6539

Polyimide microfluidic devices (MFDs) have been attached enormous significance because of its excellent organic-solvent inertness, biocompatibility, and thermal stability. In this paper, a novel fabrication method based on the thought of additive manufacturing, which is adding materials layer by layer from bottom to top, was used to construct a multilayer polyimide MFD. The MFD has sophisticated three-dimensional (3D) microchannels with adjustable cross-sectional geometries and high bonding strength, which leads to good reagent mixing performance, large surface-to-volume ratio, and great durability. Starting from a single polyimide film, ultraviolet (UV) laser was utilized to ablate microchannels on the film. Due to the studies over the influence of UV laser on the channel width, the microchannel edge shape is under control, varying from trapezoid to rectangle. From monolayer to multilayer MFDs, thermal bonding with fluorinated ethylene propylene (FEP) nanoparticle dispersion as the adhesive was adopted to stack polyimide films tightly with precise alignment. In this way, microchannels can be connected vertically between layers to form 3D structures. Besides, a homogeneous adhesive interlayer and polyimide-FEP mixing regime were formed, which can provide high bonding strength. Results of computational fluid dynamics simulation of 3D microchannel structures and organic synthesis experiment revealed that our device has great reagent mixing efficiency and promising application prospects in diverse research fields, especially organic chemical and biological studies.

Fe2O3 short nanorods, nanorods and nanowires were prepared by a facile hydrothermal method by using different flexible ligands (oxalic acid, succinic acid, adipic acid) as templates to adjust the L/D (length/diameter) ratios of the one-dimensional (1D) Fe2O3–nanostructures for the first time. The growth mechanism of Fe2O3 nanorods and nanowires were proposed. Their potential applications as anodes for lithium ion batteries were investigated by electrochemical analysis. This novel straightforward strategy to fabricate 1D metal oxide with different L/D ratios may provide a promising method to make advanced Fe2O3-based nanostructures for Li-ion battery applications.

An efficient and facile strategy for producing core-shell Au@Ag nanorods (NRs) with controllable width and length as excellent surface enhanced Raman scattering (SERS) substrate was proposed. Au nanodipyramids (NDPs) of three various widths were prepared by overgrowth along the radial orientation, and together with Au NDPs as seed, silver was deposited in the axial orientation to successfully obtain core-shell Au@Ag NRs with diverse length (73 nm–157 nm) and width (25 nm–43 nm). The morphology, optical properties and SERS performance of the as-synthesized Au@Ag NRs were investigated systematically. The broadly tunable UV-Vis absorption range for Au@Ag NRs as far as the near-infrared (NR) region was able to be obtained. Furthermore, the SERS property of Au@Ag NRs two-dimensional monolayer was explored by using crystal violet (CV) as Raman probe. The optimal SERS enhancement effect with enhancement factor (EF) as high as 6.13✕105 could be achieved for Au@Ag NRs with wider width and longer length, which was confirmed by the simulation results of electromagnetic (EM) field distribution by FDTD method. Our novel approach provides some facinating insights into adjusting the width of Au@Ag NRs, which also significantly influences the SERS behaviors of the Au@Ag NRs. It allows to fabricating SERS substrate with superior SERS performance compared to previously reported Au@Ag NRs only with tunable length via direct overgrowth. Besides, this as-compounded Au@Ag NRs are expected to have promising application and significant value in other fields.

Development in additive manufacturing is exceptionally rapid than the expected forecast so far and it has traced out new dimensions in engineering applications. 3D printing technology becomes more glamorous when Skylar Tibbits incorporated the concept of “Time” as a fourth dimension by encapsulating smart materials in current additive manufacturing technique. Materials having an explicit response to external stimuli over a certain time span are designated as smart materials and additive manufacturing of such time-dependent, programmable, and intelligent materials is termed as 4D printing. In 4D printing, primary 3D printed configuration switched exclusively into a transformed shape when exposed to an external stimuli, e.g. heat, light, water, chemical, electric current, magnetic field or pH. Perhaps, additive manufacturing technology seems to be superseded exclusively by this modern technology in forthcoming years, and much effort is demanding from every discipline to actualize this technology. A task-oriented entire landscape of 4D printing followed by a comprehensive smart material perspective is presented in this review. Graphical abstract set forth a route to the complete process comprehension. Moreover, other components of 4D technology like customary techniques, computational challenges, reversibility and current stature of 4D printing are probed through recent experimental and theoretical literature. Finally, potential applications of 4D printing are summarised with promising research directions and outlook. 4D printing: A future insight in additive manufacturing.

The Pre-Caspian basin is one of the most prolific in terms of oil and gas exploration and hydrogen and carbon compounds energy production around the world. The major hydrogen and carbon compounds reservoirs are Carboniferous reef and platform hydrogen-carbonate rocks. The original fluids under subsurface conditions contain 15% hydrogen sulfide and 4% carbon dioxide. Acid hydrogen and carbon compounds reinjection is not only an environmentally friendly solution for disposal of produced greenhouse gases but also enhances oil recovery and supplies more fuel energy. On the other hand, the presence of fractures makes hydrogen-carbonate reservoir characteristics nature more complicated than conventional sandstone reservoirs, which leads to a tremendous challenge to evaluate the gas injection process. In this work, a dual-porosity dual-permeability formulation was used to model the dual-medium nature incorporating matrix system with high porosity and low permeability and fracture network with low porosity and high permeability. After matching PVT experiments, a ten pseudo-components fluid model was generated for running compositional simulation. The miscible hydrogen and carbon compounds injection was simulated as an effective enhanced oil recovery approach. Sensitivity analysis such as timing of injection gas, injection rate, well spacing and completion interval have proposed the optimal condition for the miscible hydrogen and carbon compounds flooding. The recommended optimum hydrogen and carbon compounds injection scenario is twice higher oil recovery compared with natural depletion. The results of this study illustrate further the practicability of pseudo-components splitting and lumping for compositional simulation to evaluate the performance of hydrogen and carbon compounds injection processes, and are of great importance using the dual-porosity dual-permeability method performing numerical simulation of naturally fractured hydrogen-carbonate reservoirs.

Mechanical properties of aluminum alloy/stainless steel joint including tensile strength, bending angle, impact toughness, and fatigue property were evaluated, and the effects of friction pressure and rotational speed were also discussed in this work. Results showed that the intermetallic compound (IMC) layer was formed at the bonding interface of the joint, and a thicker IMC layer was observed in the outer region of the joint, and the thickness decreased slightly in the edge region. The thickness of the IMC layer increased with increasing rotational speed. As friction pressure increased, the tensile strength of the joint gradually increased. Joint strength reached to the maximum tensile strength of 323 MPa when the rotational speed and friction pressure were 1100 rpm and 180 MPa, respectively. With the increase of friction pressure, the bending angle of the joint first increased and then decreased. The bending angle reached to 94°, and the welded joint had the excellent bending ductility. The average impact-absorbing energy of joints was 14.47 J, and the maximum fatigue cycle number of joints could reach to 1.25 × 105.

The lead-free (1−x)(0.8Na0.5Bi0.5TiO3-0.2 K0.5Bi0.5TiO3)-xBi(Mg2/3Nb1/3)O3 ceramics were prepared using pressureless solid-state sintering for compositions x ≤ 0.4. At 120 °C, the recoverable energy storage density (Wrec) of x = 0.2 sample reached as high as 0.80 J/cm3 under the electric field of 90 kV/cm, significantly better than the other literature reported Na0.5Bi0.5TiO3 based samples. The fine-grained sample maintained high insulation resistivity (1011 Ω·m order) from 25 °C to 200 °C, which contributes to large breakdown electric field at high temperatures and leads to the excellent energy storage characteristics. This work could broaden the applications of Na0.5Bi0.5TiO3 based materials in building high-temperature multi-layer energy storage capacitor.

This work reports a microsphere laser at ∼2.0 μm in a Tm3+-doped ZrF4-BaF2-YF3-AlF3 (ZBYA) fluoride glass. The ZBYA glass microsphere was fabricated by reflowing the tip of a 1.0 mol% Tm3+-doped ZBYA glass fiber with a CO2 laser. By using a fiber taper for input and output coupling in the Tm3+-doped ZBYA microsphere, single and multi-mode laser outputs at around 2.0 μm were observed under 808 nm laser excitation. The radiation lifetime and emission cross-section of Tm3+ ions in ZBYA glass were calculated to be 6.42 ms and 5.86 × 10−21 cm2, respectively. Our results indicate that the Tm3+-doped ZBYA fluoride glass has potential applications for 2.0 μm lasers.

A new type of electrochemical sensor based on multi-walled carbon nanotubes(MWCNTs), K2H4SiW11CuO39·6H2O(SiW11Cu) and gold nanoparticles(AuNPs) was prepared for the simultaneous detection of bisphenol A and acetaminophen. Differential pulse voltammetry(DPV), cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) were used for electrochemical characterization, and Fourier transform infrared spectroscopy(FTIR) was used to characterize the structure of polyoxometalates. Electrochemical experimental results show that the composite modified electrodes have good electrochemical activity as well as current response values of bisphenol A and acetaminophen when pH=7.0. At the same time, the modified electrode exhibits good stability and reproduction, and has good anti-interference ability to other substances. In practical application, the sensor obtained satisfactory results.

A new type of three-dimensional (3D) serpentine microchannel reactor was fabricated by thermally bonding stacked polyimide films to greatly improve the mixing efficiency by transversal vortices at ...

In this study, we prepared Au nanospheres (NSs)@Ag nanorods (NRs) for colorimetric monitoring of hypochlorite (ClO–). The sensing strategy is based on the redox reaction between Ag and ClO–, which ...

In this research, the effect of stress relief annealing heat treatment on mechanical properties, microstructure, and residual stresses of a severe plastic deformation technique, known as constrained groove pressing (CGP), was investigated. For this purpose, the CGP process was performed on the commercial pure copper sheet with 3-mm thickness. The hardness, strength, homogeneity, microstructure, and residual stresses before and after stress relief annealing heat treatment were evaluated. Hardness and homogeneity on the surface and thickness were investigated and strength in both of groove direction and transverse groove direction were determined. Also, microstructure was studied along the thickness of CGPed samples, and the contour method was used for 2D residual stress measurement. The results indicate, with increasing number of CGP passes, hardness, strength, and homogeneity increase, while the mean grain size and residual stress decrease. Stress relief annealing reduces the mean grain size in the first pass but increases the mean grain size in the subsequent passes, causing a decrease of mechanical properties. Also, stress relief annealing increases residual stresses due to increasing microstructure heterogeneity.

Thermal depolarization is an insurmountable obstacle to the application of piezoceramics and there is still controversy about its physical origin. In this work, taking four representative piezoceramics (0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3, 0.2Pb(Zn1/3Nb2/3)O3-0.8Pb(Zr0.5Ti0.5)O3, 0.36BiScO3-0.64PbTiO3 and Ba0.85Ca0.15Ti0.9Zr0.1O3) as an example, by using a designed in-situ Berlincourt-type high-temperature d33 meter, combined with variable temperature X-ray diffraction and dielectric temperature spectrum test, it was confirmed the depolarization behavior is directly related to the structural phase transition, meanwhile it is reasonable to apply the peak value of piezoelectric coefficient with temperature, Tdp, as the depolarization characteristic temperature. More importantly, the original in-situ varied temperature d33 meter design helps to investigate the temperature dependent piezoelectric mechanism of various piezoceramics.

Corrosion tests were conducted in a high-temperature high-pressure (HTHP) autoclave to simulate the conditions of CO2 auxiliary steam drive in gas injection wells. Weight loss tests were performed with the sheets of N80 and 9Cr steels under the testing conditions. The morphology and composition of corrosion products were explored by SEM, EDS, XRD and XPS. The corrosion resistance of 9Cr steel was better than that of N80 steel under the testing conditions. The corrosion rates of N80 and 9Cr met the application requirements in CO2 auxiliary steam drive. The results broke the constraint in ISO-15156 standards. The corrosion process of N80 steel was mainly affected by the flow velocity. However, the corrosion process of 9Cr steel was mainly affected by temperature. The corrosion resistance of 9Cr steel depended on the FeCO3 content of Cr-rich layer, which was closely related to temperature. The low flow velocity influenced the diffusion process of N80 steel corrosive ions, whereas the high flow velocity influenced the integrity of corrosion scales. Considering the influence of flow velocity on the corrosion of tubing and casing, in the gas injection well, 9Cr steel and N80 steel were, respectively, selected as the materials of tubing and casing.

Based on the strong requirement for self-powered devices, energy harvesting by utilizing piezoelectric materials has recently attracted extensive attention. Transduction coefficient (d33·g33) is the core parameter of the piezoelectric energy harvesting materials, which is directly determined by the ratio of the piezoelectric charge constant (d33) to the dielectric constant (er). Unfortunately, traditional solid solution design method generally causes a simultaneous increase or decrease in both d33 and er, making it difficult to obtain a high d33·g33. In this work, a composite design strategy was proposed to separate the synergistic change of d33 and er. This was achieved by introducing lower-er ZnAl2O4 secondary phase into the popular 0.2Pb(Zn1/3Nb2/3)O3–0.8Pb(Zr1/2Ti1/2)O3 (PZN–PZT) perovskite matrix. Encouragingly, the er value rapidly decreased, while d33 value improved within a certain range compared to those of pure PZN–PZT. This was ascribed to the formation of fine domain structures in composites caused by the heterogeneous interfacial effect. Subsequently, the cantilever beam type piezoelectric energy harvesters (PEHs) made from the optimal composites exhibited a high power density of 4.0 μW mm−3 at 1 g acceleration. More importantly, PEHs could harvest vibrational energy from the operating motor to charge a capacitor and instantly drive wireless micro-sensors, demonstrating their potential application in self-powered electronics. Under the guide of the composite design strategy proposed in this work, more high performance piezoelectric energy harvesting materials can be built in the future.

In this work, both Finite element simulated method and contour method experimental measurement are used to obtain residual stresses of different Titanium welded alloys, the results show that the maximum of the residual stress is mainly related to the internal restraint degree which formed inside of the thickness, the distribution of the residual stress depends primarily on the shape of weld shape. The heating stage plays a major role in relaxing the residual stress in this research. 95% of the residual stress is relieved in the temperature rising period, and about 75% of it is relieved in the temperature rising period when the temperature is above 500°C.

Investigation and evaluation of dyes play a vital role in the process of introduction novel labels and their corresponding sensing methods, which signify opportunities for the development of biosensors. This chapter introduces applications of various dyes as labels in biosensing. Bio-recognition molecules with dyes transduce biological information into measurable optical, electrochemical, magnetic or other kinds of signals for quantification. The dyes used in this field were summarized and reviewed according to their signal types, namely colorimetric, fluorescent and electrochemical. Some dyes can transduce signals between multiple physical signals. For some most important dyes, detailed descriptions were given focused on their unique properties, labeling methods and sensing mechanisms.

In this work, β-cyclodextrin porous polymers (P-CDPs) functionalized novel covalent organic frameworks (P-CDPs/COFs) were synthesized by a simple and facile method. After combined with Pd2+ via electrostatic interaction, the Pd2+@P-CDP/COFs nanocomposites were prepared and as novel electrode materials to fabricate NF sensor. Due to the host-guest recognition, excellent adsorption performance and catalytic performance of Pd2+ @Pd2+@P-CDP/COFs, the prepared sensor exhibited excellent electrochemical performance for detecting NF under the optimum conditions with the linear range of 0.08 to 7.0 μM and 7.0 to 100.0 μM, and the low detection limit 0.031 μM(S/N=3). Additionally, with the advantages of good selectivity and reproducibility, the obtained sensor could be successfully applied to measure NF with satisfactory results in the real medicinal samples of Norfloxacin eye-drops. Our findings paved the way for the design of modified COFs materials as a sensing platform and expanded the application of COFs modified materials in drug testing.