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The topological electronic structure plays a central role in the non-trivial physical properties in topological quantum materials. A minimal, hydrogen-atom-like topological electronic structure is desired for researches. In this work, we demonstrate an effort towards the realization of such a system in the intrinsic magnetic topological insulator MnBi2Te4, by manipulating the topological surface state (TSS) via surface modification. Using high resolution laser- and synchrotron-based angle-resolved photoemission spectroscopy (ARPES), we found the TSS in MnBi2Te4 is heavily hybridized with a trivial Rashba-type surface state (RSS), which could be efficiently removed by the in situ surface potassium (K) dosing. By employing multiple experimental methods to characterize K dosed surface, we attribute such a modification to the electrochemical reactions of K clusters on the surface. Our work not only gives a clear band assignment in MnBi2Te4, but also provides possible new routes in accentuating the topological behavior in the magnetic topological quantum materials.

Recently, some criminals have begun to use multimedia steganography to conduct covert communication, such as transmitting stolen trade secrets. After using steganalysis to find covert communication entities, obtaining their locations can effectively help criminal forensics. This paper proposes a novel localization method of wireless covert communication entity for post-steganalysis. The method is based on hybrid particle swarm optimization and gray wolf optimization to improve localization precision (ILP-PSOGWO). In this method, firstly, the relationship model between received signal strength (RSS) and distance is constructed for the indoor environment where the target node exists. Secondly, dichotomy is used to narrow the region where the target node is located. Then, the weighted distance strategy is used to select the reference point locations with strong and stable RSS. Finally, the intersection region of the reference points is taken as the region where the target node is located, and the hybrid PSOGWO is used to locate and optimize the target node location. Experimental results demonstrate that ILP-PSOGWO can maintain high stability, and 90% of the localization errors are lower than 0.9012 m. In addition, compared with the existing methods of PSO, GWO and extended weighted centroid localization (EWCL), the average localization error of ILP-PSOGWO is also reduced by 28.2–49.0%.

The microstructure and properties of CrFeNiNbTi HEA coating on 40CrNiMoA steel synthesized by laser cladding were investigated. The CrFeNiNbTi HEA coating had a dendritic microstructure, whose volume ratio of dendrite (VRD) decreased linearly with the increasing distance from the surface. The refractory element Nb preferred to dissolve into the dendritic solid solution with FCC lattice structure, and Ti promoted the precipitation of the Laves phase Fe2Ti as a strengthening phase. The microhardness of the CrFeNiNbTi HEA coating can reach up to 685.23 HV0.3, which was approximately twice the microhardness of the substrate. The enhanced hardness was owing to solid solution strengthening and precipitated-phase strengthening. The hardness of micro-area test proved that the dendrites strengthened by the solid solution of Nb were harder than the interdendritic region, even though Fe2Ti with high hardness tended to be distributed in the interdendritic region. The wear mechanisms were abrasive wear, adhesive wear, and oxidative wear. The oxide film produced on the surface of the coating at the later stage of friction reduced the increment of wear mass loss, which significantly improved the wear resistance of the coating. The passive film formed on the surface of the CrFeNiNbTi HEA coating slowed the corrosion of the coating by Cl- in the solution, so the corrosion resistance of the coating was superior than that of 40CrNiMoA steel. In summary, the CrFeNiNbTi HEA coating had exceptional wear resistance and corrosion resistance using 40CrNiMoA steel substrate as reference.

Although the certified power conversion efficiency of organic-inorganic perovskite solar cells (PSCs) has reached 25.7%, their thermal and long-term stability is a major challenge due to volatile organic components. This problem has been a major obstacle to their large-scale commercialization. In the last few years, carbon-based all-inorganic perovskite solar cells (C−IPSCs) have exhibited high stability and low-cost advantages by adopting the all-inorganic component with cesium lead halide (CsPbI3−xBrx, x = 0 ~ 3) and eliminating the hole-transporting layer by using cheap carbon paste as the back electrode. So far, many astonishing developments have been achieved in the field of C−IPSCs. In particular, the unencapsulated CsPbBr3 C-IPSCs exhibit excellent stability over thousands of hours in an ambient environment. In addition, the power conversion efficiencies of CsPbI3 and CsPbI2Br C-IPSCs have exceeded 15%, which is close to that of commercial multicrystalline solar cells. Obtaining high-quality cesium lead halide-based perovskite films is the most important aspect in the preparation of high-performance C-IPSCs. In this review, the main challenges in the high-quality film fabrication process for high performance C-IPSCs are summarized and the film fabrication process strategies for CsPbBr3, CsPbIBr2, CsPbI2Br, and CsPbI3 are systematically discussed, respectively. In addition, the prospects for future film fabrication processes for C-IPSCs are proposed.

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.

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.

Shielded metal arc welding and welding thermal simulation experiment were carried out for constructional steel containing 0% V and 0.10% V, and the microstructure, precipitation feature, microhardness HV0.2, and −20 °C impact value in the welding heat affected zone (HAZ) were investigated. The results showed that in the coarse-grained heat affected zone (CGHAZ), V and N were completely dissolved in the matrix of steel containing 0.10% V to promote the growth of prior austenite grains, meanwhile the fraction of high angle grain boundaries (HAGBs) decreased, thereby leading to the mean −20 °C impact value decreases from 87 J to 18 J. In the grain refined heat affected zone (GRHAZ), V(C, N) precipitates experience re-dissolution and re-precipitation at grain boundaries, V–N microalloying changes the microstructure from lath bainite + granular bainite + small amount of polygonal ferrite to polygonal ferrite + pearlite + martensite, thereby leading to the mean microhardness decreases from 335 HV0.2 to 207 HV0.2, and the mean −20 °C impact value decreased from 117 J to 103 J. In the intercritical heat affected zone (ICHAZ), V(C, N) precipitates experience re-dissolution, re-precipitation, and growth, causing the formation of micro-sized V(C, N) precipitates, thereby leading to the mean −20 °C impact value decreases from 93 J to 62 J.

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...

Although Generative Adversarial Network(GAN) has obtained remarkable achievements in the image analysis and generation, its exploration in GAN-based curve clustering is still limited. The latent space of curve data is often used for clustering. However, the distance geometry in the latent space does not reflect the inherent clusters. In this paper, we propose CPGAN(Curve Clustering Architecture based on Projected Latent Vector of Generative Adversarial Network) for the clustering of curve dataset. Firstly, a novel GAN network structure, which utilizes a projector ${P}$ (composed of the transposed convolutional network) to reconstruct the latent space of curve data, is proposed. CPGAN utilizes the concatenation of discrete code and Gaussian noise as a latent vector to preserve the implicit signal and structure of the cluster. Secondly, the loss function with two regularizations for CPGAN is proposed to guarantee the robustness and effectiveness of the model. Based on these, the jointly trained projector ${P}$ is used to participate in the clustering process, while the generator can be used in the generating process. Finally, the spectral dataset from the LAMOST survey, the UCI dataset, and the UCR dataset are used as experimental data to evaluate clustering performance, the robustness of CPGAN, and further application on anomalous detection. CPGAN presents higher results than other methods.

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.

Analyzing the fast search and find of density peaks clustering (DPC) algorithm, we find that the cluster centers cannot be determined automatically and that the selected cluster centers may fall into a local optimum and the random selection of the parameter cut-off distance ${d_{c}}$ value. To overcome these problems, a novel clustering algorithm based on DPC & PSO (PDPC) is proposed. Particle swarm optimization (PSO) is introduced because of its simple concept and strong global search ability, which can find the optimal solution in relatively few iterations. First, to solve the effect of the selection of the parameter ${d_ {c}} $ on the calculation density and the clustering results, this paper proposes a method to calculate that parameter. Second, a new fitness criterion function is proposed that iteratively searches ${K} $ global optimal solutions through the PSO algorithm, that is, the initial cluster centers. Third, each sample is assigned to ${K} $ initial center points according to the minimum distance principle. Finally, we update the cluster centers and redistribute the remaining objects to the clusters closest to the cluster centers. Furthermore, the effectiveness of the proposed algorithm is verified on nine typical benchmark data sets. The experimental results show that the PDPC can effectively solve the problem of cluster center selection in the DPC algorithm, avoiding the subjectivity of the manual selection process and overcoming the influence of the parameter ${d_{c}}$ . Compared with the other six algorithms, the PDPC algorithm has a stronger global search ability, higher stability and a better clustering effect.

The $\text{H}\alpha $ emission line in rest wavelength frame of optical spectra is valuable characteristics for nebulae detection. Searching and recognizing the spectra with $\text{H}\alpha $ emission line from massive data are necessary for the further study, while the most of methods existed currently do not adapt to such spectral data, especially for the spectra with weak $\text{H}\alpha $ emission line. To address this issue, a new algorithm (named WEDA) for detection of spectra with $\text{H}\alpha $ emission line is provided in this paper. Firstly, the difference factor $\mu $ between the line characteristics of the specific data is defined as its weight in recognizing of the whole lines table. Secondly, a tuning function $\mathit {f(\tau, \delta)}$ based on the momentum formula is defined to update the weights during the process. In this step, the spectra with $\text{H}\alpha $ emission line are analysed and classified as 3 different situations. The amount of spectra with $\text{H}\alpha $ emission line is different in 3 different situations, so the speed of weight of update is different in 3 different situations. The weight of update helps us detect the data containing weak $\text{H}\alpha $ emission line in the 3 situations. Based on this, a new integrated algorithm especially for the detection of the spectra with $\text{H}\alpha $ is provided. In the end, by using several spectral datasets from the DR5 of LAMOST survey, experiments results indicate that the WEDA shows higher accuracy basically unaffected by the dataset size and the signal to noise ratio(SNR) than the other similar algorithms.

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.

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.

The gaseous PVTx properties of 1,1,1,2-tetrafluoroethane (R134a) + 1,1,1,3,3-pentafluoropropane (R245fa) mixtures were measured at pressures from 124 to 650 kPa, temperatures from 300.15 to 335.15 K and the compositions of R134a from 0.30 to 0.55 mass fraction using the Burnett isothermal expansion method. The uncertainty of temperature measurement was estimated to be within ±10 mK temperature, the pressure was within ±4 kPa, the mass fraction was within ±0.3%, and the compression factor was within ±0.06%. Based on the experimental PVTx property data, the densities and gas virial equation of the mixed refrigerants at the different temperatures and pressures were fitted. It provided detailed data for the further research on the performance of the Organic Rankine Cycle adopting the new alternative refrigerant.

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.

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.

As one of the most important techniques in data mining, clustering has always been highly concerned. Most clustering algorithms have encountered challenges, such as the difficulty of cluster centers selection, the artificial determination of the number of clusters ${K}$ , low accuracy of clustering, and uneven clustering efficiency of different data sets. Considering the difficulty of cluster centers chosen, a new algorithm of fast selecting the initial cluster centers is proposed in this paper. Generally, cluster centers are those data points with higher density, smaller radius threshold and far away from each other, this method uses ${MNN}$ ( ${M}$ nearest neighbors), density and distance to determine the initial cluster centers. First, the neighborhood radius ${r}$ of each point is measured by ${MNN}$ based on distance, and the average value of all ${r}$ is marked as $\bar {r}$ ; second, the densities $\rho $ of each point in the region within $\bar {r} $ are calculated; and then, factor ${f}$ is defined to describe the probability that points become cluster centers, based on which, the initial cluster centers are determined by the candidates with bigger ${f}$ . In the end, the method proposed in this paper is tested by using 12 groups of typical benchmark data sets and applied in the stellar spectral data of ${LAMOST}$ survey. The experiment results compared with the other six algorithms indicate that the initial cluster centers obtained by this method are of higher quality than that of the six algorithms. Meanwhile, the initial cluster centers of spectral data are of good agreement with the actual stellar classifications.

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.

This paper investigates the bond behavior of deformed bars embedded in recycled aggregate concrete (RAC) subjected to uniaxial lateral pressure. Sixty pull-out specimens with different levels of recycled coarse aggregate (RA; i.e. 0%, 30%, 50%, 70% and 100%) were manufactured, and then these specimens were submitted to test the bond-slip curves under different levels of uniaxial lateral pressure (i. e. 0, 0.1fcu, 0.2fcu, and 0.3fcu). The effects of lateral pressure and RA content on bond strength, peak slip, residual bond strength and bond energy density were analyzed; the bond-slip relationship between RAC and deformed bars was also established. The results demonstrated that the bond strength of reinforced RAC is comparable with that of reinforced natural aggregate concrete (NAC). It is feasible to adopt RA in structural application but the bond ductility should be improved before it can be reliable reused. With the incremental of lateral pressure, the peak slip, relative bond strength and the bond energy density gradually increased, while the relationship between these parameters and RA content could not be clearly observed. In addition, the parameter value for descending bond-slip curve was abruptly decreased after lateral pressure was applied, demonstrating that the lateral pressure increased the bond ductility of RAC specimens.

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 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.

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.

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.

The design and fabrication of economically viable anode catalysts for the methanol oxidation reaction (MOR) have been challenging issues in direct methanol fuel cells (DMFCs) over the decades. In this work, a composite electrochemical catalyst of Pd-coupled Ag and ZnO for the possible replacement of expensive Pt catalysts in DMFCs is successfully prepared. The as-made Pd@Ag/ZnO exhibits specific activity, which is 1.8-fold, 2.8-fold, and 4.6-fold higher than that of a Pd/ZnO catalyst, 20% Pd/C catalyst and Pd black, respectively. The improvement of the catalytic mechanism is likely due to the synergistic interaction between Pd@Ag and ZnO. The density functional theory (DFT) calculation results confirm that Ag doped into Pd weakens the adsorption of CO, dramatically improving the capability to resist CO poisoning.

In big data era, the special data with rare characteristics may be of great significations. However, it is very difficult to automatically search these samples from the massive and high-dimensional datasets and systematically evaluate them. The DoPS, our previous work [2], provided a search method of rare spectra with double-peaked profiles from massive and high-dimensional data of LAMOST survey. The identification of the results is mainly depended on visually inspection by astronomers. In this paper, as a follow-up study, a new lattice structure named SVM-Lattice is designed based on SVM(Support Vector Machine) and FCL(Formal Concept Lattice) and particularly applied in the recognition and evaluation of rare spectra with double-peaked profiles. First, each node in the SVM-Lattice structure contains two components: the intents are defined by the support vectors trained by the spectral samples with the specific characteristics, and the relevant extents are all the positive samples classified by the support vectors. The hyperplanes can be extracted from every lattice node and used as classifiers to search targets by categories. A generalization and specialization relationship is expressed between the layers, and higher layers indicate higher confidence of targets. Then, including a SVM-Lattice building algorithm, a pruning algorithm based on association rules, and an evaluation algorithm, the supporting algorithms are provided and analysed. Finally, for the recognition and evaluation of spectra with double-peaked profiles, several data sets from LAMOST survey are used as experimental dataset. The results exhibit good consistency with traditional methods, more detailed and accurate evaluations of classification results, and higher searching efficiency than other similar methods., Comment: 19 pages,11 figures,IEEE Access accepted

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.

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 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.

This paper develops a new bond stress-slip relationship for reinforced concrete, which considers the evolution of the concrete confinement capacity due to splitting failure of concrete cover. Considering fracture characteristics of the concrete, the improved thick-walled cylinder model is used to analyze the radial stress and radial deformation at the interface between rebar and concrete for different damage stages. A new assumption of circumferential deformation is proposed to estimate the deformation field of the inner cracked concrete, and the linear crack profile is assumed to calculate the distribution of cohesion on the crack surface. The radial strain is calculated with elastic constitutive relation including the Poisson’s effect. The descending branch of the confinement model can be derived with the linear response between the radial stress and radial deformation. The presented concrete confinement model can be transformed into bond stress-slip relationship based on the stress and deformation analysis at the interface. Comparing with experimental results, it is indicated that the results calculated with bond stress-slip relationship proposed in this paper is more reasonable.

The complete compressive stress-strain curve of recycled aggregate concrete (RC) after exposure to high temperatures improves to assess the post-fire behavior of reinforced RC structures. In this paper, 60 specimens containing different levels of recycled coarse aggregate (RCA; i.e., 0, 30, 50, 70 and 100%) were produced to study the residual compressive stress-strain relation of RC after exposure to high temperatures. Those specimens designed for thermal temperatures were initially heated to temperatures of 300, 400 and 500°C for 6 hr and then being submitted to test the compressive stress-strain curves after cooling to ambient temperature. The test results were compared with specimens tested at room temperature (about 20°C). The effect of RCA and high temperatures on residual compressive strength, peak strain and elastic modulus are discussed and the empirical formulas for these parameters are also established. The recommended equation for the compressive constitutive relation for conventional concrete in the Chinese code for the design of concrete structures (GB50010-2010) was adopted to fit the test data and was shown to be applicable to heated RC for different temperatures.

The fiber pullout is a main failure after the fiber is broken in the tension of glass fiber reinforced polymer (GFRP) bolt. In this paper, the numerical analysis is done on the distribution of both fiber normal force and interface shear stress. The results show that, on the ideal interface, the fiber pullout occurs from the lower end to the upper end of the matrix gradually, and both the normal stress of the fiber and the shear stress of the ideal interface gradually increase from the lower end to the upper end. With the increase of the interface layer thickness, the shear stress concentration area on the interface is enlarged while the stress applied is reduced, and the displacement of GFRP deformation is increasing sharply. This means that the capacity of GFRP deformation is enhanced. As a soft elastic body, the interface layer with a smaller elastic modulus can make the fiber stress and the interface shear stress sharply small and well dispersed. In addition, the load can be effectively transferred to the reinforced phase fibers in a bigger interfacial layer elastic modulus with a certain strength.

The performance of perovskite solar cells (PSCs) is extremely dependent on the morphology and crystallization of the perovskite film. However, the complete conversion of PbI2 to perovskite and controlling the perovskite crystal size as well as its surface morphology are challenging in the conventional two-step sequential deposition method. We herein present a facile method involving the use of a polar solvent additive in an inter-diffusion two-step sequential deposition method to achieve a high-quality perovskite film. The results showed that the addition of a small amount of DMF solvent into the MAI precursor solution could help the complete conversion of PbI2 to perovskite, and at the same time could also reduce the pinholes, improve the film morphology, increase the grain sizes and enhance the film absorption ability. The improved perovskite film quality results in the boosting performance of PSCs. Consequently, an optimized device with power conversion efficiency as high as 19.2% is obtained. This current method provides a highly repeatable route for enhancing the PSC performance with the inter-diffusion sequential solution deposition method.