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A novel yield criterion based on CPB06 considering anisotropic and tension-compression asymmetric behaviors of magnesium alloys was derived and proposed (called M_CPB06). This yield criterion can simultaneously predict the yield stresses and the Lankford ratios at different angles (if any) under uniaxial tension, compression, equal-biaxial and equal-compression conditions. Then, in order to further describe the anisotropic strain-hardening characteristics of magnesium alloy, the proposed M_CPB06 criterion was further evolved to the M_CPB06ev model by expressing the parameters of the M_CPB06 model as functions of the plastic strain. As the model was developed, the stresses and Lankford ratios of AZ31B and ZK61M magnesium alloys at different angles under tensile, compressive and through-thickness compressive conditions were used to calibrate the M_CPB06/M_CPB06ev and the existing CPB06ex2 model. Calibration results reveal that compared with the CPB06ex2 yield criterion with equal quantity of coefficients, the M_CPB06 criterion exhibits certain advancement, and meanwhile the M_CPB06ev model can relatively accurately predict the change of the yield locus with increase of the plastic strain. Finally, the M_CPB06ev model was developed through UMAT in LS-DYNA. Finite element simulations using the subroutine were conducted on the specimens of different angles to the rolling direction under tension and compression. Simulation results were highly consistent with the experimental results, demonstrating a good reliability and accuracy of the developed subroutine.

Making the substrates form highly dense, homogeneous, and stable hotspots regions is important for the sensitive detection of surface-enhanced Raman spectroscopy (SERS). A new strategy based on solvent-induced (SI) SERS substrate to form a stable interval of the hotspot for detection was explored and the enhancement factor (EF) of our SERS substrates could reach about 1.4 × 109. By preferential adsorption of alcohol solutions by Q-Sepharose microsphere (QSS) in mixed water and alcohol solutions, the size of QSS@AuNPs was dynamically adjusted and the spacing between gold nanoparticles (AuNPs) was adjusted to keep the substrate in the optimal hotspot mode for the sensitive detection of SERS in the liquid state. As a real application case, such a SI-SERS strategy was employed to determine SCN- in saliva and a limit of detection (LOD) of about 10-10 M could be achieved.

A novel surface-enhanced Raman scattering (SERS) nanoprobe based on a reactive strategy was designed for the first time to determine the concentration of superoxide anion radical (O2˙−) produced from titanium dioxide by a UV radiation process. A limit of detection (LOD) for O2˙− of 9.0 nmol L−1 could be attained.

The mechanical behavior of AZ31B magnesium alloy was studied through uniaxial tensile tests at strain rates of 0.001, 1, 100, and 1000/s. The results show that an increase in the strain rate results in a gradual increase in the flow stress. Considering that the original Johnson–Cook (J–C) model cannot adequately describe the flow stress of AZ31 magnesium alloy at different strain rates, a rate-dependent modified Johnson–Cook (M-J–C) model was proposed, and the coefficients were calibrated according to the experimental results. The calibration and validation show that the M-J–C model has a high accuracy in characterizing the flow stress of AZ31B magnesium alloy and can well predict the hardening curve of ZK60 and AM60 magnesium alloys at different strain rates in the literature. In addition, the variation in the fracture strain with different strain rates was characterized. The fractography was studied to reveal the mechanism of underlying fracture. The proposed M-J–C constitutive model combined with a failure criterion was developed and coded into LS-DYNA through the user subroutine UMAT. The comparison between the simulation and the experiment shows that the developed subroutine is accurate enough to simulate the plastic and fracture behaviors of AZ31B magnesium alloy at different strain rates.

CoCrFeNiTi high-entropy alloy (HEA) coating with constituent elements of equal molar ratio was fabricated by laser cladding on 40CrNiMoA alloy steel. The microstructure, microhardness, wear resistance, and corrosion resistance of the coating have been investigated. The coating exhibits typical dendritic morphology, composing of solid solution phase with FCC structure, χ phase with cubic structure, and Co2Ti phase with HCP structure. The microhardness of the CoCrFeNiTi coating (about 700 HV0.3) is about four times higher than that of the CoCrFeNi. According to the estimated strength increment by the simple rule of mixture, the significant improvement of microhardness of the coating can be mainly attributed to second-phase strengthening rather than solution strengthening. The CoCrFeNiTi HEA coating with the wear rate of 0.84 × 10−7 mm3/(N m) has better wear resistance than the substrate and CoCrFeNi HEA. The wear mechanisms of the coating were abrasive wear and low-cycle fatigue wear in the dry sliding process, accompanied by oxidation wear. The CoCrFeNiTi coating with the corrosion rate of 1.41 × 10−2 mm/a exhibits poorer corrosion resistance than CoCrFeNi HEA, due to the formation of microanode and microcathode regions. Yet, the sensitivity to localized corrosion of the CoCrFeNiTi coating is reduced, due to the formation of a thicker passivation film.

MoN and Mo2C are important functional materials; however, due to the high activation energy barrier in their nucleation, their synthesis generally requires harsh conditions such as high temperature...

Copper foil is widely used in printed circuit board because of its good conductivity, especially in flexible printed circuit board. A traditional two-layer flexible copper clad laminate avoids introduction of an additional adhesive, its application range is improved, but its peel strength is low. Laser, as an efficient and clean energy, has great potential application value in this field. Based on the research of parameters of laser transmission welding copper foil and polyethylene terephthalate (PET), to prepare a two-layer flexible copper clad plate and improve the bonding strength of welding joints in laser welding, this study proposes to change the surface roughness of the copper foil and preheat the weldment in the welding process. The bonding properties of the welded joint were tested by a micro-tensile test bench. Through the study of laser parameters, a welding speed of 300 mm/min was used to explore the surface roughness of the copper foil, it was found that the overall welding effect was best when the surface roughness of the copper foil was 400 nm. The effect of the preheating temperature on the bonding properties of weldments was studied by preheating samples at different temperatures. A high-speed camera was used to record the instantaneous tensile state of the welding sample, the surface roughness of the debonding sample under different conditions was measured by atomic force microscope. The interface morphology of the sample was characterized by optical microscope, X-ray photoelectron spectrometer, and high-resolution field emission scanning electron microscope. The bonding mechanism was revealed, and the reason for the strength improvement of the welding joint was discussed. In view of the research results of the PET/copper foil high-strength bonding in this paper, it shows that the laser welding technology has an important application prospect in the production of a two-layer flexible copper clad laminate.

Prevalent contamination of water by cadmium ion (Cd2+) brings environmental risk, which threatening to human health including renal dysfunction, reduced lung capacity, and some cancers. It calls for rapid, sensitive and selective protocol to analyze Cd2+ on field. In this work, specific Raman probe is rationally designed by gold nanoparticles (AuNPs) functionalized with tripeptide glutathione (GSH) and Rhodamine 6G (R6G) (denoted as R6G/GSH/AuNPs), which is explored for indirectly determining trace Cd2+ in river water. Based on chelating interaction between GSH and Cd2+ to form tetrahedral Cd(SG)4, which trends easy detachment from R6G/GSH/AuNPs. With increasing Cd2+ concentration, the Raman probe without protection of GSH happens due aggregation and Raman signal of R6G increases correspondingly. The R6G/GSH/AuNPs-based Raman detection of Cd2+ in river water shows rapidness, excellent sensitivity, selectivity and good repeatability. Limit of detection of 10 ppb with a widely linear range of 0.5–20 ppm could be achieved. It could be perspective that such Raman probe could be extended to be used for on-site monitoring trace Cd2+ in river water system.

In this work, an eco-friendly corrosion inhibitor was synthesized by embedding 4-methyl-4H-1,2,4-triazole-3-thiol (4-MTTL) into phytic acid (IP6) micelles via heating (donated as IP6@4-MTTLx). The corrosion inhibitor, IP6@4-MTTLx microcapsules with self-healing capability, can be used for metal protection from corrosion in 3.5 wt% NaCl aqueous solution. By means of electrochemical impedance spectroscopy (EIS) and electrochemical polarization, the high inhibition performance of such micelle-based coating on the model metal of copper has been investigated, which is attributed to the synergistic effect of the 4-MTTL molecules and the IP6@4-MTTLx microcapsules. Damage to the coating by external force can be self-healed by leakage of 4-MTTL inside IP6@4-MTTLx microcapsules to seal physically and chemically the cracks. Keywords: Copper, Corrosion inhibitor, Self-healing, Phytic acid micelles, 4-Methyl-4H-1,2,4-triazole-3-thiol (4-MTTL)

In this paper, to improve the hardness and wear resistance, AlCoCrFeNiSi HEA coatings were synthesized on AISI 304 stainless steel by laser cladding. The microstructure, chemical composition, constituent phases, microhardness, wear resistance and corrosion resistance of the coating were analyzed by scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), x-ray diffraction (XRD), Vickers microhardness tester, pin-on-disk tribological tester and electrochemical workstation, respectively. The experimental results showed that the coating possessed a single body-centered cubic (BCC) phase structure (Fe-Cr). Si element was dissolved into Fe-Cr solid solution, resulting in severe lattice distortion. The dislocation density of the coating was as high as 1.07 × 1014 m−2. Therefore, the microhardness (630.36 HV0.3) of the HEA coating was significantly improved by the effect of solid solution strengthening and dislocation strengthening. The coating exhibited excellent wear resistance, and abrasive wear was effectively avoided. The wear mechanism of the coating involved mainly oxidation wear and slight adhesion wear. The corrosion resistance of the coating was better than that of AISI 304 stainless steel in 3.5% NaCl solution. In conclusion, the AlCoCrFeNiSi HEA coating prepared by laser cladding can provide excellent wear protection to stainless steel at no expense to its own corrosion resistance.

To improve the service life of valve retainer in the engine exhaust system, the NiCoCrAlY alloy coating was fabricated on compacted graphite cast iron by laser cladding. Microstructure and high-temperature wear resistance of the coating were studied. The coating exhibits a refined dendritic structure. The M23C6 nano-precipitates with rod-shape are embedded the γ(Fe, Ni) solid solution dendrites, and the M7C3 nano-precipitates are distributed in the inter-dendrite region. The average nano-hardness of the coating and the substrate are measured as 4.08 GPa and 3.96 GPa, respectively. The wear morphologies and coefficient of friction variation reveal that the friction layer formed at 25°C and 600°C is a mechanical mixing layer and a composite layer, respectively. The coating possesses excellent wear resistance at 600°C due to the formation of a dense oxide film. The main component of the oxide film is identified as Fe2O3, Fe3O4, Al2O3, CrO2, CrO3 and Cr2O3.

AlCoCrFeNiTix (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) HEA coatings reinforced by in-situ TiC particles were successfully prepared on AISI1045 steel via laser cladding. The coatings are made up of two BCC phases identified as Fe-Cr and Al-Ni phases, and a few in-situ TiC phases with a shape of granular in micro-nano scale. Ti element prefers to dissolve into the Al-Ni phase and refines the equiaxed grains. The AlCoCrFeNiTi1.0 HEA composite coating with the highest volume fraction of TiC particles phase (2.6%) exhibits the highest average microhardness (860.1 HV0.3). It is found that the composite coating is strengthened by the effect of solid solution strengthening, dispersion strengthening, and fine-grain strengthening. The wear behaviour of the coatings was tested at 25 °C and 600 °C, respectively. The micromorphology and chemical composition analysis of the wear scars show that oxidation wear occurs in addition to adhesive wear during the wear process at 600 °C. The oxidation products are identified as Al2O3, CoO, Cr2O3, Fe2O3, Fe3O4, and NiO in terms of the calculation of flash temperature and Gibbs free energy. The calculation results of wear rates show that the AlCoCrFeNiTi1.0 composite coating exhibits the best wear resistance.

The chirality of amino acids plays a key role in many biochemical processes, with the development of spectroscopic analysis methods for the chiral differentiation of amino acids being significant. Normal Raman spectroscopy is blind to chirality; however, chiral discrimination of tyrosine (Tyr) (or phenylalanine, Phe) enantiomers using Raman spectra can be achieved assisted by the construction of a simple chiral selector (i.e., cysteine (Cys)-modified Au nanoparticles (NPs)). Due to the synergetic effect between Cys and the Au NPs, the characteristic Raman scattering intensities of the Tyr (or Phe) enantiomer with the same chirality of Cys are enantioselectively boosted by over four-fold compared with those of the counter enantiomer of Tyr (or Phe). The large differences in the Raman signals allow for the determination of enantiomeric excess. Interestingly, such enantiomeric discrimination is not revealed by the common chiral analysis method of circular dichroism spectroscopy. Consequently, it is anticipated that Raman spectroscopy based on molecular vibrations will find broad applications in chirality-related detection with high sensitivity and species specificity.

Ultrasonic-assisted soldering was used for Ta/Sn/Al interconnection. The effects of ultrasonic waves on the dissolution and nucleation behavior of Al in Ta/Sn/Al joints during ultrasonic-assisted soldering were investigated. The cavitation induced by ultrasound waves lead to the continuous dissolution of the Al from substrate into molten Sn and the content of Al in solder increased rapidly. When the Al content reached saturation in the ultrasonic field, Al precipitated in the solder as second phase and nucleated on the substrates at the same time that Al dissolve into molten Sn from substrate. The behavior of nucleation on the Al substrate suppressed the growth of Al content in solder. The Al content in the bond was in dynamic equilibrium due to the dissolution and nucleation of Al. The maximum shear strength and bonding ratio of the joints were approximately 16 MPa and 86%, respectively.

This study proposed a damage identification method compared with the existing ones, based on relative curvature difference and frequency perturbation theory, showing sensitivity to local damage by changes in the curvature mode and high recognition accuracy of frequencies. Considering the relative curvature difference as a damage index, numerical simulation is used for a simply supported beam under single and multiple damage conditions for different damage degrees. The damage is located according to the curvature mode curves, and the damage degree is qualitatively determined. Based on the perturbation theory, the damage equations are established by the changes between frequencies before and after damage, and the damage localization and degree are verified and determined. Effectiveness of the proposed method for identifying damage at different conditions is numerically investigated. This method potentially promotes the development of damage identification of beam structures.

The rapid development of mechanical systems’ miniaturization has expanded the demand for higher precision and performance micro formed parts. For improving the forming height and quality of formed parts, and studying the influences of the stress annealing and imprinting times on the forming as well as surface roughness (Sa) of the formed parts, this paper proposed a composite process of imprinting times and stress annealing on warm laser shock imprinting (WLSI) to realize the precision forming of the aluminium foil. In this research, the WLSI experiments were carried out with the imprinting temperature, imprinting times, and stress annealing treatment as variables. Subsequently, the forming height, surface roughness, and surface oxidation of the formed parts were measured, the loading–displacement curve were monitored, the transient deformation process induced by WLSI was divided four stages (deformation stage, rebound stage, vibration stage, and stable stage), and the residual stress distribution of the formed parts were simulated and analyzed by ABAQUS. Finally, the influences of the above three factors on the formed parts were discussed and explicated, and these results showed that the imprinting times and stress annealing can improve effectively the forming effect of WLSI.

Axial compression tests were conducted on AZ31B magnesium and A6063 aluminum thin-walled square tubes with varied lengths and induced features at different compression rates. In compression, the magnesium tubes exhibited a “local buckling and fracture” mode, with three fracture patterns, i.e. “horizontal”, “double-oblique”, and “spiral” fractures. In general, the magnesium tube showed an inferior crashworthiness to the aluminum square tube. In addition, the effects of L/W ratio, strain rate and induced features on the crashworthiness of thin-walled square tubes were investigated. With an increase in the L/W ratio (L and W represent the tube length and width, respectively) from 1 to 4, the maximal force and global specific energy absorption decreased in a power-law trend for the magnesium tubes, while they remained approximately constant for the aluminum tubes. Furthermore, as the compression rate increased from 5×10−5 to 10 m/s, the primary crashworthiness parameters of the magnesium tubes increased in an approximately exponential manner, while for the aluminum tubes, they changed slightly. Finally, the involved induced features were proven to be not an effective method to improve the specific energy absorption of magnesium tubes, thus, more trigger types, locations, and sizes will be evaluated in future to improve the energy-absorption ability.

We report a facile approach to prepare high density of tiny Pt nanoparticles less than 3 nm loaded on the polyaniline hollow tubes in uniform way. Polyaniline hollow tubes in diameter of micro size are synthesized via the polymerization of aniline onto the template of sulfonated electrospun polystyrene fibers, followed by the removal of core polystyrene fibers. The as-prepared highly crystalline Pt nanoparticles on the surface of polyaniline microtubes show the much higher electrochemical active surface area of 90.49 m2/g, high mass catalytic current density, good durability toward the methanol oxidation reaction as well as the excellent carbon monoxide tolerance. The hollow-structure-conductive-polymer- based synthesis strategy for high performance catalyst in this study could be applied to produce other catalysts with the enhanced activities.

The mechanical properties, especially the yield behavior, of AZ31B and ZK61 M magnesium alloys were comparatively investigated in this study. Series of uniaxial tension, uniaxial compression, shear and through-thickness compression (equi-biaxial tension) tests were conducted to obtain yield strengths and Lankford ratios (r values) under different strains and angles to their rolling directions and further the anisotropic characteristics as well as the tension-compression asymmetric features of the materials were analyzed. Furthermore, different yield criteria were adopted to represent yield behaviors of two magnesium alloys and their applicability on such magnesium alloys were compared. Results show that both magnesium alloys show apparent anisotropic and tension-compression asymmetric yield behavior. Compared with AZ31B, ZK61 M performs more remarkably in the anisotropic behavior and more intricately in tension-compression asymmetry and hardening features with changes of angles to the rolling direction and strain. The associated yield criteria of Hill1948, Yld2000-2D and CPB06 cannot concurrently represent anisotropic plastic yield and flow behaviors of AZ31B and ZK61 M magnesium alloys well; while the corresponding yield criteria based on non-associated flow rule can ideally describe these two aspects meantime. Among them, under tension and shear conditions, the non-associated Yld2000-2D criterion provided the most accurate predicting results than the other criteria. Regarding the tension-compression asymmetric characteristics of magnesium alloys, the non-associated model based on the CPB06 was introduced which makes concurrent prediction of tension-compression yield stress and Lankford ratio of these two materials possible. As a result, the comprehensive prediction capability of this model is fairly outstanding among all of three models. This study can provide basis for selection of plastic models, calibration technique and further application in numerical modeling.

Developing detection method for trace copper ions (Cu2+) has attracted great attention since Cu2+ ions would threaten to human health, including cellular toxicity, liver damage, and neuro degenerative diseases. In this work, adding L-cysteine (L-Cys) into inositol hexaphosphate (IP6) modified Ag nanoparticles (designated as L-Cys/IP6@Ag) induces the certain aggregation of nanoparticles, resulting in increasng the surface enhanced Raman scattering (SERS) signal of rhodamine 6 G (R6 G). The presence of Cu2+ ions could be adsorbed by IP6 and the concentrated Cu2+ ions could further selectively oxide Cys molecules under certain pH value, which disperses the IP6@Ag again and decreases the SERS signal of R6 G. The linear range of determination of Cu2+ ions is from 10−5 to 10-1° M as well as a low detection concentration is of 10 pM. Furthermore, the L-Cys/IP6@Ag-R6 G-based SERS sensor has been successfully applied to detect trace Cu2+ in river water.

AISI1045 steel is widely used in mechanical engineering. In spite of the favorable toughness and strength, the surface properties of AISI1045 steel, such as hardness, wear resistance and corrosion resistance, are not ideal. Therefore, surface modification of AISI1045 is necessary, especially for the parts suffering severe work condition. Laser cladding is a promising surface modification technology. In this work, the AlCoCrFeNiTi high-entropy alloy (HEA) coatings were prepared on the AISI1045 steel to improve its surface properties. Metallurgical bonding is obtained between the coating and the substrate. The microstructure and surface properties of the coating were characterized by scanning electron microscope, energy-dispersive spectrometry, x-ray diffraction, electrochemical workstation, microhardness tester and pin-on-ring wear tester. The microstructure of the coating produced by laser cladding is dendritic. The AlCoCrFeNiTi HEA coating is mainly composed of disordered body-centered cubic phase (Fe-Cr), ordered B2 phase (AlNi) and intermetallic phase (Ti-rich). The coating shows excellent abrasion resistance and corrosion resistance in comparison with the substrate. The maximum microhardness of the coating reaches approximately 865 HV, which is 4.5 times of AISI1045 steel.

Cast iron is an iron-carbon alloy widely used in mechanical engineering. Nickel-base or cobalt-base alloy coatings prepared by laser cladding can improve the surface properties of cast iron, thereby increasing the service life of the components; however, due to the poor weldability and high carbon content of cast iron, the use of laser cladding to prepare alloy coatings faces many difficulties. To reduce the brittleness of the bonded interface, laser cladding was applied to the surface of cast iron using a multilayer deposition strategy. Through testing of the single-track laser cladding, the causes of defects in the coating are analysed, including poor bonding, slag inclusions, and pores. An analytical model based on mass and heat conservation is developed, and a processing window of laser tracks without defects is determined thereby. NiCoCrAlY alloy coating prepared by overlapping laser tracks mainly consists of γ-(Fe, Ni) dendrites and interdendritic M7C3 and M23C6 carbides. Although there are no cracks in a single laser track, cracks are detected when laser tracks are overlapped under the same process parameters. The increase in laser power helps to reduce cracking susceptibility on this occasion. The morphology of the grain in NiCoCrAlY alloy coating is mainly epitaxially grown columnar crystals. The increase in microhardness of the coating is mainly attributed to ductile dendrites, precipitated carbides, and grain refinement.

Malondialdehyde (MDA) is a biomarker of lipid peroxidation and intracellular oxidative stress and can also be used to monitor food freshness. However, fast, accurate and ultrasensitive detection of MDA remains a challenge. In this work, a chemical reaction tandem surface-enhanced Raman spectroscopy (SERS) method was applied for trace MDA detection by gold nanoparticles (AuNPs) enriched on the surface of Q sepharose spheres (AuNPs@QSS). After derivatization of MDA with 2-thiobarbituric acid (TBA), TBA-MDA adduct could be directly detected by SERS in the reaction media utilizing AuNPs@QSS as SERS substrate. QSS play multiple roles as AuNPs adsorbent, AuNPs carrier against aggregation in acid environment, and TBA-MDA adduct enricher. SERS detection in solution and the micro-scale homogeneous AuNPs distribution on QSS surface contribute to the improved reproducibility of the substrate. This method has a wide linear range (0.33 μM to 3.3 mM in a liquid environment), low limit of detection (∼10−10 M at dry state) and has already been applied in the direct determination of MDA in oil samples without standard addition.

In this paper, X ray diffraction test and Scanning electron microscope test were designed to investigate the effect of limestone powder (LP) in manufactured sand on the hydration products and microstructure of full recycled coarse aggregate concrete samples. The results showed that most of LP was inactive, except only a small quantity of LP participated in the hydrating reaction at mid-late period. This small amount of LP did not change the composition of hydration products but varied their morphology. Some amount of LP filled in the pore structure of cement matrix and in the interface between recycled coarse aggregate and new harden cement paste, improving the compactness of the cement matrix and the interfacial transition zone. The nucleation around the LP who filled in the pore structures was also observed, and the hydration products gradually formed and subsided on the surface of these LP and accelerated the cement hydration.

Sensitive and selective detection of target analyte is very important in many fields such as commodity inspection and quality monitoring. In this work, we constructed a MIPs@AgNPs surface-enhanced Raman scattering (SERS) sensor by in-situ preparation of silver nanoparticles (AgNPs) inside molecularly imprinted polymers (MIPs) matrix for bisphenol A (BPA) detection. In-situ formed AgNPs are evenly distributed and closely packed in the matrix, which is beneficial for hot spot formation and analyte-AgNPs affinity. Our MIPs@AgNPs sensor shows good BPA selectivity against structurally related molecules such as bisphenol AF (BPAF) and diethylstilbestrol (DES). Excellent sensitivity of this MIPs@AgNPs sensor is demonstrated with the detection limit of at least 5 × 10−8 mol L−1 for BPA. This sensor is reliable for the quantitative detection of BPA in real samples, validated with results of HPLC. Regeneration of this kind of SERS sensor can be easily realized by solvent rinsing and NaBH4 reduction. Together with the advantages of ease-of-fabrication, selective recognition, sensitivity and reusability, this kind of MIPs@AgNPs SERS sensor will have a promising practical applications.

A micro-energy high frequency ultraviolet pulse laser was introduced for fabricating the micro pattern on pure aluminum foil by laser shock transferring. The copper mesh mold (mesh size: 400# and 1000#) and pure aluminum foil were used to investigate the effect of laser pulse energy and overlap ratio on micro pattern transferring. A FEM model was adopted to simulate the aluminum foil deformation and plastic strain in laser shock process. To investigate the micro forming mechanism of laser shock transferring, the micro morphology of significant area on processed micro pattern was observed by atomic force microscope (AFM). The experimental results revealed that the depth of transferred micro pattern increased with the increasing of single pulse energy and overlap ratio within certain range. The forming depth of aluminum foil imprinted from 400# mold was larger than that of 1000#, and more sensitive to pulse energy and overlap ratio. The aluminum foil on mold bars was smoother than that of on mold holes. The study demonstrated that the micro-energy ultraviolet pulse laser shock can realize the precise, controllable, fast and ultrahigh strain rate fabrication of surface microstructure.

Up to date, many efforts have been done to improve the performance of surface-enhanced Raman scattering spectroscopy (SERS) substrates, but the fabrication of a stable, sensitive and uniform SERS substrate in a simple way also remains a challenge. In this work, we report a very convenient way to prepare a durable, uniform, flexible and sticky SERS substrate by dropping noble metal nanoparticles colloids on highly transparent fluorescent quantitative PCR sealing membranes, designated as HTFQ-PCR-M. HTFQ-PCR-M based SERS substrate exhibits high sensitivity, superior reproducibility, good stability and thermal stability. We apply such to directly collect thiram pesticide residues on the peel of fruit and do Raman measurement, to analyze dividually methylene blue and rhodamine B in mixture by the aid of thin layer chromatography plate via “paste and peel off” approach. Moreover, HTFQ-PCR-M based SERS substrate can keep its SERS activity at 90℃. As a perspective, HTFQ-PCR-M based SERS substrate could offer a great practical potential for on-spot identification of trace target molecules in various real samples.

The Palladium/polydopamine (Pd/PDA) litchi-like nanoclusters are synthesized via a two-step route. The resultant product is characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the electrochemical properties were evaluated by cyclic voltammetry (CV) and chronoamperometry. Notably, the as-prepared litchi-like Pd/PDA nanoclusters show superior catalytic properties for methanol electro-oxidation in an alkaline medium due to unique Pd dots adhered at PDA surface providing a large electrochemically active surface area (ECSA). Additionally, the high concentration of oxygen functional groups on PDA is essential to the removal of carbonaceous species from the adjacent at the Pd sites. This PDA-based straightforward synthesis strategy offers a new pathway for developing highly active electrocatalysts with aid of special organic polymer.

Waste rubber wood (RW) is the castoff of rubber plantation with abundant reservation but without high-value utilization. In this study, cellulose with high purity has been efficiently isolated from waste RW and further processed into cellulose nanocrystals. By means of acetylation, more hydrophobic cellulose-based products, namely acetylated rubber wood cellulose (Ac–RWC) and acetylated rubber wood cellulose nanocrystals (Ac–RW–CNC) had been attempted as reinforcing fillers for fabricating two series of PLA-based composite films via spin coating instead of currently prevailing melt compounding technique. To ensure a uniformed dispersion of fillers in PLA matrix, the addition of reinforcing filler should be equal to or less than 5% based on the film dry weight. Compared with pure PLA film, the Ac–RWC reinforced PLA composite films are more thermally stable, while the Ac–RW–CNC reinforced PLA composite films on the other hand exhibit more enhanced performance in mechanical properties and the degree of crystallinity. The highest tensile strength (55.0 MPa) and Young’s modulus (3.9 GPa) were achieved for 5%Ac–RW–CNC/PLA composite film.

In this study, 2A14-T4 Al-alloy T-joints were prepared via stationary shoulder friction stir welding (SSFSW) technology where the stirring pin’s rotation speed was set as different values. In combination with the numerical simulation results, the macro-forming, microstructure, and mechanical properties of the joints under different welding conditions were analyzed. The results show that the thermal cycle curves in the SSFSW process are featured by a steep climb and slow decreasing variation trends. As the stirring pin’s rotation speed increased, the grooves on the weld surface became more obvious. The base and rib plates exhibit W- or N-shaped hardness distribution patterns. The hardness of the weld nugget zone (WNZ) was high but was lower than that of the base material. The second weld’s annealing effect contributed to the precipitation and coarsening of the precipitated phase in the first weld nugget zone (WNZ1). The hardness of the heat affect zone (HAZ) in the vicinity of the thermo-mechanically affected zone (TMAZ) dropped to the minimum. As the stirring pin's rotation speed increased, the tensile strengths of the base and rib plates first increased and then dropped. The base and rib plates exhibited ductile and brittle/ductile fracture patterns, respectively.

The purpose of this study was to optimize modification conditions of selenized garlic polysaccharides (sGPS) and investigate its structural characterization, immune and antioxidant activities. Herein, selenized garlic polysaccharides (sGPS) were prepared using by HNO3-Na2SeO3 selenylation method. And then modification conditions of sGPS were optimized through L9 (34) orthogonal test. The structural characterization of sGPS were identified by the Fourier-transform infrared (FT-IR), Solid-State nuclear magnetic resonance (NMR) spectra, X-ray diffraction (XRD) and thermogravimetric (TGA). The morphology of sGPS was detected using scanning electron microscope (SEM) and transmission electron microscope (TEM). In vivo investigation showed that sGPS significantly improved serum hemagglutination-inhibition (HI) antibody titers against Newcastle disease virus, enhanced secretory IgA (sIgA), IFN-γ, IL-2 secretion in jejunum and trachea irrigation compared with vaccine immunized control group. Furthermore, it showed that sGPS had some effects on the antioxidant activities in livers of chickens. In conclusion, the optimal modification conditions of sGPS were as follows: reaction temperature was 70 °C, the dosage of Na2SeO3 was 400 mg and reaction time was 6 h. The selenylation modification of garlic polysaccharides (GPS) could improve its immune and antioxidant activity in chickens.

The surface precision and mechanical properties were the bottleneck of laser shock imprinting extensive application in micro/nano manufacturing. In this work, the high-quality and precise nanoscale line textures were fabricated on aluminum foil, and the influence of pulse laser energy and laser pre-shock processing on the preparation of nanoscale line textures was also investigated experimentally. The morphology of nanoscale line texture was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM), which obtained the best laser shock imprinting parameter. The microstructure and dislocation changes of laser shock imprinted aluminum foil were analyzed by transmission electron microscope (TEM), which explained the improvement of nanoscale line textured aluminum foil in electrochemical and mechanical properties. The nanotribological properties of nanoscale line textured aluminum foil were characterized by the AFM with sharp probe and SiO2 colloidal probe. The experimental results indicated that nanoscale line textured aluminum foil had the effect of reducing friction and adhesive force between AFM probe and aluminum foil. The laser shock imprinting can fabricate high-accuracy nanoscale line textures on aluminum foil. Compared with the original aluminum foil, the morphology, mechanical properties, electrochemical performance and nanotribological properties of nanoscale line textured aluminum foil were improved.

For real application, it is an urgent demand to fabricate stable and flexible surface-enhanced Raman scattering (SERS) substrates with high enhancement factors in a large-scale and facile way. Herein, by using the electrospinning technique, a hydrophobic and flexible poly(styrene-co-butadiene) (SB) fibrous membrane is obtained, which is beneficial for modification of silver nanoparticles (Ag NPs) colloid in a small region and then formation of more &ldquo, hot spots&rdquo, by drying, the final SERS substrate is designated as Ag/SB. Hydrophobic Ag/SB can efficiently capture heterocyclic molecules into the vicinity of hot spots of Ag NPs. Such Ag/SB films are used to quantitatively detect trace triazophos residue on fruit peels or in the juice, and the limit of detection (LOD) of 2.5 &times, 10&minus, 8 M is achieved. Ag/SB films possess a capability to resist heat. As a case, 6-mercaptopurine (6MP) that just barely dissolves in 90 &deg, C water is picked for conducting Ag/SB-film-based experiments.

Solar water evaporation is a promising and environment-friendly approach to relieve global water scarcity issues. Currently, many reports show that the voids and porous structure are beneficial to the absorption of solar energy to generate water steam. Herein, carbon nanospheres with central cavity structures are rationally designed by the one-step NaN3/fluorinated graphite deflagration method. The Na clusters derived from NaN3 deflagration are not only provided as the hollow templates but also react with fluorinated graphite to release heat, further boosting the formation of hollow carbon nanospheres (HCSs). Benefiting from the diversity of carbon nanomaterials, rough surface, unique hollow structures, and numerous micron/submicron holes, the light absorption ability, heat localization, and water supply capacity of HCSs have been significantly enhanced. Because of these advantages, the HCS-3 exhibits an excellent water evaporation efficiency of 92.7% at 1 kW m-2, which is much higher than that of carbon nanospheres, graphene oxide, and even most of the previous carbon materials. In addition, we demonstrated that the HCSs have a long-term stability and high efficiency of production of drinkable water and purifying various types of wastewater, including seawater, strong acid/alkaline water, and water containing dyes. To sum up, the deflagration synthetic technology as a facile and ultrafast process can be a new insight for future photothermal material design.

Waffle-like anodized aluminum oxide homogeneously immobilized with Ag nanoparticles (AAO/Ag) is rationally designed and fabricated as surface-enhanced Raman scattering (SERS) substrate. The as-prepared SERS substrate is characterized with transmission electron microscope (TEM), scanning electron microscopy (SEM), UV–Vis spectrophotometer, and Fourier transform infrared spectrometer (FT-IR). The AAO/Ag substrate shows good uniformity of the Raman signals (RSD = 7.02%) due to waffle-like AAO supporting the well-dispersed Ag nanoparticles. For real application, the AAO/Ag substrate is used for rapid determination of chloramphenicol (CAP) in honey with low detection limit (4.0 × 10−9 mol L−1) and good linearity from 1.0 × 10−5 to 1.0 × 10−8 mol L−1 based on the SERS peak at 1348 cm−1. The better accumulation in the short pore path of AAO improves the target molecule approaching into the vicinity of hot spots of Ag nanoparticles. The high selectivity for CAP is attributed to the strong interaction between -NO2 group in CAP and the composite substrate.

Polydopamine (PDA) and silver (Ag) nanoparticles were first generated on chiral silica nanofibers and then detached from silica to form PDA/Ag composites. The as-obtained PDA/Ag showed surface-enhanced Raman scattering (SERS) activity but very weak circular dichroism optical activity. Interestingly, the PDA/Ag substrates could make a pair of tyrosine (or phenylalanine) enantiomers show different Raman scattering signal intensities, where the differences could reach 3 times. In contrast, PDA/Ag prepared by using racemic or achiral silica did not exhibit such discrimination performance. Therefore, this research offered a novel SERS-based enantiomeric differentiation method with the assistance of plasmonic metal-containing substrates stemmed from intrinsically chiral inorganic silica.

Iron-nitrogen (Fe-N) co-doped carbon nanomaterials are promising catalysts for oxygen reduction reaction (ORR) with outstanding catalytic activity at low cost. Here, we demonstrate a facile bottom-up strategy to fabricate Fe, N, B co-doped bamboo-like carbon nanotubes using ionic liquid as dopant source. We show that the synergistic effect of Fe, N, B in the mesoporous carbon structure can derive excellent ORR activity, for which the FeNB/C-800 catalyst delivers an onset potential of 0.97 V (vs. reversible hydrogen electrode, RHE), a half-wave potential of 0.81 V (vs. RHE) and a high limiting current density (5.59 mA cm−2), comparable to a commercial Pt/C. The catalyst also shows good methanol tolerance as compared to Pt/C catalyst. This work highlights a bottom-up strategy for creating ternary Fe, N, B sites on carbon nanotubes using boron-containing ionic liquid precursor.

Surface-enhanced Raman scattering (SERS) is a powerful technique for sensitive detection, but it normally has difficulty in multicomponent detection in a complex system, especially for simultaneous analysis of mixture of heavy metal ions. In this work, a simple paper chromatography tandem SERS (PC-SERS) separation/detection platform is proposed by ion-sputtering gold on a filter paper. Based on SEM results, the great electromagnetic field inside nanogaps of Au nanoislands on the paper surface is evaluated with FDTD simulation. It is found that the PC-SERS platform has good uniformity (RSD = 10.12%) and long-time stability. The as-prepared PC-SERS platform was applied to efficiently separate and detect a mixture of pesticides (MG, MB, and CV) in pond water without any pretreatment process, and the limits of detection (LODs) were down to 10 nM. As a crucial application for food safety, several heavy metal ions such as Cd2+, Cu2+, and Ni2+ in grinded rice were successfully detected by the PC-SERS method taking advantage of the sandwich structure based on 4-mercaptobenzoic acid (4-MBA) molecules, which were modified onto sputtering the Au filter paper and gold nanoparticles (Au NPs) to link metal ions and acted as Raman signal molecules. All the LODs for metal ions were down to 1 μM. Due to the easiness of fabrication, good reproducibility, and simple pretreatment step, the PC-SERS platform holds promise in multicomponent detection in a real sample.

A Si3N4/(W, Ti)C graded nano-composite ceramic tool was fabricated and its performance in high speed turning iron-based alloys GH2132 was investigated compared with homogeneous and commercial ceramic tools. The chip morphology, cutting forces, cutting temperature, tool life and failure mechanisms and machined surface roughness were recorded and analyzed. The results showed that with the increasing cutting speed the resultant cutting force shows a tendency to first increase and then decrease while the cutting temperature increases gradually. Straight continuous chips, bending continuous chips, twist continuous chips and snarled chips form in turn. Saw-tooth chips tend to form when the cutting speed is more than 200 m/min. The graded tool shows longer tool life especially at the cutting speed of 150 and 200 m/min compared with the homogenous and commercial ceramic tools. Tool failure modes mainly include grooving on the rake face, notching on the flank face, abrasion and adhesion. The grooving on the rake face tends to decrease while notching on the flank face tends to increase as cutting speed increases. Surface roughness of the machined iron-based super-alloys is relatively high due to the serious adhesion. Better surface roughness can be got using the graded tool.

Electronic structures are critical characteristics that determine the electrical, magnetic and optical properties of materials. With the capability of directly visualizing band dispersions and Fermi surfaces, angle-resolved photoemission spectroscopy (ARPES) has emerged as a powerful experimental tool to extract the electronic structures of materials and the coupling of these electronic structures to different degrees of freedom in crystal lattices. In the past three decades, advances in instrumentation and light sources have significantly improved the accuracy and efficiency of ARPES experiments. These advances have enabled the application of ARPES in novel material systems to aid our understanding of their physical properties and behaviours. In this Review, we give a brief introduction to the principles of ARPES and outline its applications in different material systems, with a focus on topological quantum materials and transition metal dichalcogenides.

A well-dispersed SiO2@Layered hydroxide cupric benzoate (SiO2@Cu-LBMS) with a hierarchical structure have been synthesized by a facile method. The layered hydroxide cupric benzoate with a structure of layered basic metal salt (Cu-LBMS) was directly deposited on the surface of silica spheres without any blinder. The morphology of the SiO2@Cu-LBMS nano-microsphere was observed by SEM, and the reaction conditions was also discussed. In addition, the XRD patterns and FTIR spectra provide consistent evidence to the formation of SiO2@Cu-LBMS nano-microspheres. The release behavior and drug loading capability of SiO2@Cu-LBMS microspheres were also investigated by using ibuprofen, aspirin and salicylic acid as model drugs. The results indicated that the drug loading capability of SiO2@Cu-LBMS nano-microspheres was much larger than layered hydroxide cupric benzoate, and the releasing time was significantly prolonged than layered hydroxide cupric benzoate and their physical mixture.

A composite silver nanoparticle (AgNP) ink was prepared by mixing the small AgNPs (10 nm in diameter), large AgNPs (50 nm in diameter), ethylene glycol, and deionized water at a mass ratio of 4:2:3:51. By spraying a sodium hydroxide solution, the AgNP pattern printed on the polyethylene terephthalate film surface can be sintered at room temperature with a minimum electric resistivity of 12.11 μΩ·cm, 0.7 times smaller than that sintered at 150 °C. Our study confirmed that OH− ions can partially replace citrates on AgNP surfaces at room temperature, resulting in the loss of the encapsulated density of citrates. Such loss can induce the particle agglomeration, cause the sintering necks to form, and finally create the three-dimensional conductive networks. This research is of great importance to the rapid manufacturing of low-cost, low-environmental-impact and high-performance flexible printed circuits.

Diethylhexyl phthalate(DEHP) is a kind of plasticizer，which is regarded as environmental hormone due to reproductive toxicity to human body and also has the risk of breast cancer, endometrial cancer and liver cancer after long-term intake. In this work, a rapid surface enhanced Raman scattering (SERS) technique to detect the DEHP residue level in food products is developed by optimizing the synthesis of a hexakisphosphate (IP6) stabilized Au@Ag@IP6 nanoparticles. For further improvement of detection sensitivity, such SERS substrate is treated by using 1-dodecanethiol (DT) to enable its capability of capturing more DEHP molecules into the vicinity of SERS hot spots. Au@Ag@IP6/DT-based Raman protocol could analyze DEHP down to 10−8 M. By using a portable Raman system, the simple and reliable SERS method is used to on-site determine trace DEHP in real sample of energy drinks, which meets the requirement of national standard.

A Si3N4/(W, Ti)C graded nano-composite ceramic tool material was developed and its high temperature flexural strength and fracture toughness were studied. With increased testing temperature, the flexural strength demonstrates a tendency to first decrease gradually and then decrease sharply, and the transition temperature is 1000 °C. The softening effect of glassy phases, the oxidation effect and the surface cracks result in the gradual decrease of flexural strength while the growth and merge of microcracks and cavities results in the sharp decrease. The fracture toughness under elevated temperatures increases gradually and then decreases dramatically, and the transition temperature is 1000 °C as well. The plastic deformation behavior, microcrack toughening effect and the healing effect of SiO2 layer result in the gradual increase of fracture toughness while liquefaction of the grain-boundary phase results in the sharp decrease. Due to reasonable composition distribution and induced compressive residual stress in the surface layers, the graded material shows a significantly better high temperature properties than the homogenous one.

Large-scale preparation of hollow echinus-like PdCuCo alloy nanostructures (HENSs) with a high surface area-to-volume ratio, rich active sites, and relatively efficient catalytic activity has attracted considerable research interest. Herein, we present an economic and facile approach to synthesize HENSs by galvanic exchange reactions using Co nanospheres as sacrificial templates. Moreover, the catalytic activity could be adjusted via changing the composition of the catalyst. The composition, morphology, and crystal structure of the as-obtained nanomaterials are characterized by various techniques, such as inductively coupled plasma atomic emission spectrometry, transmission electron microscopy, and X-ray diffraction. Electrochemical catalytic measurement results prove that the Pd75Cu8Co3 catalyst obtained under optimal preparation conditions exhibits 10-fold higher activity for ethanol oxidation in comparison with the commercially available 20% Pd/C catalyst. The eminent performance of the Pd75Cu8Co3 elec...

The microcavity perovskite solar cells (PSCs) are designed by sandwiching the perovskite layer between the ultrathin Ag and opaque Ag electrodes. Compared to transparent-conductive-oxide (TCO) based PSCs, the microcavity PSCs with the bare Ag electrode show the poor optical performance due to the transmittance limit of Ag film. By introducing an optical coupling layer, the remarkably improved transmittance of the Ag electrode and enhanced light absorption in the perovskite layer are obtained. Furthermore, the better light absorption is available by adopting an optical spacer, and the resulted microcavity PSCs achieve the comparable or even higher $J_{{\text{SC}}}$ than TCO-based PSCs. This provides a guideline to design and fabricate efficient TCO-free PSCs.

The fabrication of Ag nanowire (AgNW) patterns on a working substrate is a critical step to prepare flexible/stretchable electronics. The conventional method of making AgNW patterns is based on a 2-D mask, which suffers some serious drawbacks, such as low material usage, difficulty in preparing complex patterns, and susceptibility to damaged pattern edges. To overcome these drawbacks, this study proposes the use of a 3-D mask, which when combined with a vacuum filtration system, allowed efficient fabrication of complex AgNW patterns with clear edges. In addition, we controlled the microstructure of the patterned AgNW/polydimethylsiloxane (PDMS) electrodes transferred from the membrane filter, obtaining stretchable electrodes with anisotropic electrical properties. Moreover, we greatly improved the stability and reliability of the patterned electrodes in long-term stretch/release tests by developing a PDMS/AgNW/PDMS sandwich structure. Based on these improvements, robust stretchable electrodes with a stretchability of over 80% uniaxial strain and tunable gauge factors ranging from 0.07 to 520 (a much wider range than previously reported) were fabricated by optimizing the AgNW deposition density and PDMS peel-off direction. Finally, we demonstrated the applicability of the proposed method by fabricating stretchable circuits which were able to either maintain a stable resistance or sensitively monitor various human motions, revealing its tremendous potential for applications in flexible/stretchable electronics.

The hierarchical micro/nano structures are successfully obtained on the stainless steel mesh via a simple laser direct writing technology. The as-prepared mesh reveals excellent superhydrophilic/underwater superoleophobic properties or superhydrophobic/superoleophilic properties after 1H, 1H, 2H, 2H-perfluorodecyltriisopropoxysilane modification. According to the oil density, the superhydrophilic/underwater superoleophobic mesh allows water to permeate and repels the light oil. Its oil/water separation efficiency is as high as 98.5% for the light oil. The superhydrophobic/superoleophilic mesh can be easily wetted by heavy oils while the water will be repelled, which the separation efficiency can reach 98.0% for the heavy oil. Moreover, this special wettability mesh can still maintain high separation efficiency after 20 separation cycles, which indicates the good separation stability.

The core-shell nanowires structure has increasingly attracted the attention in energetic-material applications due to the high reactive interface. However, the influences for surface density of nanowires on the exothermic capability, ignition response, even reaction process are still rarely reported, which is probability benefit to give more energy release for micron combustion. Here, CuO nanowires are prepared by electrochemical and chemical etching methods, subsequently Al is sputtered on CuO nanowires, and a series of different loading density of Al/CuO nano-thermite are prepared. As results, characterizations show that the CuO nanowires prepared by the electrochemical method has the high surface density and a homogeneous structure, which is beneficial to the contact between Al and CuO. Correspondingly, TG/DSC tests show that the heat release per unit area of nano-thermite prepared by electrochemical-sputtering is 8 times that of the product prepared by chemical-sputtering. Its obvious reduction of activation energy (181.142 kJ/mol) could be attributed to the excellence interaction of thermite components. Moreover, the high surface density structure of nano-thermite is easier to be ignited with lower ignite energy of only 10 mJ. Its significantly increase in combustion rate, flame area or intensity also demonstrated the great advantage in micron igniter or combustion devices.

Bifacial semi-transparent perovskite solar cells (PSCs) are highly attractive for improving the efficiency of tandem solar cells and extending bifacial photovoltaic applications. However, the further improvement of bifacial performance has always been limited by the semitransparent electrode. Here we report an efficient triple-layer cathode of polyethyleneimine ethoxylate/silver/molybdenum oxide (PEIE/Ag/MoOx) for hysteresis-free planar PSCs with an inverted device configuration. Firstly, the optimal thickness of Ag electrode (11 nm) is achieved by theoretical calculation, and the fabricated PSC achieves the PCE of 8.04% at indium-tin-oxide (ITO) side and 5.24% at Ag film side. Then, by introducing the MoOx (10 nm) optical coupling layer and PEIE (10 nm) interfacial modifying layer, the resulted PSC shows an obviously increased PCEs of 13.55% (ITO side) and 8.41% (Ag side), which is 60% higher than that of Ag only PSCs. The optimized PSCs has a structure of Glass/ITO/Poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate)/Methylammonium-Lead-Iodide (about 300 nm)/Phenyl-C61-butyric-acid-methyl-ester/PEIE/Ag/MoOx. It is thought that the enhanced Ag film transmittance by high-refractive-index MoOx and electron extraction ability by low-work-function PEIE contribute to the improved cathode property and bifacial PSC performance. Moreover, when a back-reflector is employed, the PCE of device could be further improved to 14.50% (ITO side) and 11.37% (Ag side).