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The transmission and distribution of moisture in cement-based materials are of great significance to the properties and durability of materials. Traditional macro-humidity monitoring equipment in civil engineering cannot capture the microscale humidity inside cement-based materials in situ. In this paper, a method of using rhodamine 6G fluorescence to characterize the change in relative humidity in cement-based materials is proposed. Two kinds of moulding processes are designed, which are premixed and smeared after moulding, and the optimal preparation concentration is explored. The results showed that rhodamine 6G can reflect the relative humidity of cement-based materials in situ by its fluorescence intensity and had little effect on the hydration heat release and hydration products of cement-based materials; the fluorescence intensity was much higher when the internal relative humidity was 63% and 75%. The research results lead the application of polymer materials in the field of traditional building materials, help to explore the performance evolution law of cement-based materials in micro scale, and have important significance for the evolution from single discipline to interdisciplinary.

Untethered robots with smart human-machine interactions can execute complex activities such as target cargo delivery or assembly of functional scaffolds. However, it remains challenging for fabricating microscale hollow hydrogel robots that can go with autonomous transformation of their geometric formations to adapt to unstructured environments. We herein report hydrogel-based microscopic hollow swarming spheres (HSSs) with anisotropic/isotropic alignments of Fe3O4 particles in the porous wall that can navigate under complex topography conditions by altering their geometric formation, including passing around or jumping over obstacles, assembling into various formation patterns, and swimming in a high-viscosity system. We introduce HSSs into a catalytic reaction model, in which HSSs as a catalyst can shift between water and oil phases to initiate or terminate the decomposition reaction of H2O2. This dynamic catalysis is expected to construct free-radical "living" polymerization for controlling the reaction rate and polymer dispersity index in the future.

The magnetocaloric effect can be used to achieve remote manipulation of soft polymer actuators for shape-programmable actuation, which plays a key role in multifunctional applications in robotics. We herein report a polymer bilayer actuator composed of an inert poly(vinylidene fluoride) (PVDF) layer and a thermal-expansive polydimethylsiloxane (PDMS) layer. Fe(0) particles (100–500 nm) were hybridized into the PDMS layer to transduce magnetic effects into heat energy. Upon exposure of the bilayer actuator to an electromagnetic field, the strong magnetocaloric effect enabled its temperature to rapidly rise to 72 °C in 4 s. At this temperature, the volume of the PVDF layer remained constant, while the PDMS@Fe layer expanded by 2.5%. This asymmetric expansion provided a theoretical basis for motility of soft polymer robots. As a result of patterning designs to endow the material with spatially-asymmetric magnetocaloric effects, the polymer robots were capable of undergoing various motions with controllable kinematics, showing a promising potential in magnetocaloric robotics.

Internal standard lines play a crucial role in the univariate quantitative analysis in portable laser-induced breakdown spectroscopy (LIBS) technology. To overcome the uncertainty of the conventional internal standard method, the distribution principles of high-quality internal standard lines were studied and revealed at the macro and micro levels, and an automatic internal standard line selection method based on the Q-value was proposed. Using this method, in the quantitative analysis of Si in low-alloy steel samples, the average relative error of cross-validation (ARECV), root mean squared error of cross-validation (RMSECV), and the limit of detection (LoD) were decreased significantly from 27.42%, 0.041 wt%, and 1060 μg g−1 to 18.65%, 0.026 wt%, and 680 μg g−1, respectively. The quantitative analysis results of Cr, Cu and Ni showed that it has excellent generalization ability. The results indicate that this method can screen out the optimal internal standard lines efficiently and accurately, which provides a new approach to improve the performance of univariate quantitative analysis in portable LIBS.

The tribological characteristics of cotton fibers play an important role in engineering and materials science, and real contact behavior is a significant aspect in the friction behavior of cotton fibers. In this study, the tribological characteristics of cotton fibers and their relationship with the real contact behavior are investigated through reciprocating linear tribotesting and real contact analysis. Results show that the friction coefficient decreases with a general increase in load or velocity, and the load and velocity exhibit a co-influence on the friction coefficient. The dynamic change in the real contact area is recorded clearly during the experiments and corresponds to the fluctuations observed in the friction coefficient. Moreover, the friction coefficient is positively correlated with the real contact area based on a quantitative analysis of the evolution of friction behavior and the real contact area at different loads and velocities. This correlation is evident at low velocities and medium load.

In this paper, the common diseases about bridge deck pavement of the completed highway in Heilongjiang province have been made practical investigation and analyze why these diseases happen. It also combines the climate features in north cold areas，from the way of using High quality modified asphalt，reducing the catalytic point temperature of pitch to improve the low temperature anti-crack property, using high strength coarse and fine aggregate，adjusting gradation of mixture aggregate and the ratio of oil to stone to improve temperature and water stability and durability for Concrete pavement project of Nao Li river bridge connected Jian San river with Hu Lin highway .From trabecular bending test、Freeze-thaw splitting test、Rutting test and Immersion Marshall test，that compares different influence research on pavement performance of bridge with Bitumen concrete bridge deck which have different polyester fiber content .The experimental result indicates the proportion of polyester fiber can clearly ameliorate the temperature stability、hypothermia anti-cracking performance and water stability of Asphalt .And within a certain range of polyester fiber content，various road performances will be improved with the increasing of polyester fiber content，and on this basis，the optimum polyester fiber content is raised.

Immediately after the demonstration of the high-quality electronic properties in various two dimensional (2D) van der Waals (vdW) crystals fabricated with mechanical exfoliation, many methods have been reported to explore and control large scale fabrications. Comparing with recent advancements in fabricating 2D atomic layered crystals, large scale production of one dimensional (1D) nanowires with thickness approaching molecular or atomic level still remains stagnant. Here, we demonstrate the high yield production of a 1D vdW material, semiconducting Ta2Pd3Se8 nanowires, by means of liquid-phase exfoliation. The thinnest nanowire we have readily achieved is around 1 nm, corresponding to a bundle of one or two molecular ribbons. Transmission electron microscopy (TEM) and transport measurements reveal the as-fabricated Ta2Pd3Se8 nanowires exhibit unexpected high crystallinity and chemical stability. Our low-frequency Raman spectroscopy reveals clear evidence of the existing of weak inter-ribbon bindings. The fabricated nanowire transistors exhibit high switching performance and promising applications for photodetectors.

Considering the development of conventional engineering materials, the research on new modern materials and the increasing demand for road infrastructure construction, significant changes regarding both the road fundamental properties and functional positioning have been taking place at an increasing pace. The roads have evolved from early structures meeting basic traffic needs to important assets with well-defined economic and environmental characteristics. Since the beginning of the 21st century, the need for smart and safe travel has steadily created new requirements for road infrastructure. The rapid development of material science and interdisciplinary research has provided viable and technical support for the design and construction of various types of new pavements, thus promoting the continuous expansion within the research field of pavement materials. Therefore, this research introduces and analyzes the technical principles, design, development, and challenges related to new pavement materials characterized by self-capture energy, self-luminescence, self-regulation, and self-healing functions, providing a reference for the future research direction. The main objective of piezoelectric self-powering pavement is to design the structure and optimize the performance of self-powering devices, and apply this technique in road engineering. A series of studies on mechanical modeling, laboratory verification and engineering application of self-powering devices show that the energy harvesting effect of embedded piezoelectric self-powering devices made of block or multilayer piezoelectric materials is considerable, and the piezoelectric self-powering pavement has a broad prospect. Thermoelectric pavement is a new type of pavement, which uses the Seebeck effect of thermoelectric materials to collect excess energy of asphalt pavement and realize green conversion of pavement energy. Meanwhile, it can effectively reduce the temperature of pavement and prolong the service life of road. The composition includes three main parts: Thermoelectric conversion device, hot end and cold end. A new type of thermoelectric asphalt pavement structure is studied in this paper. Results indicate that the power generation 0.564 V of single specimen has good application potential via monitoring the generation voltage of thermoelectric pavement in different seasons. The research of self-luminous pavement mainly focuses on the design and optimization of pavement luminescent materials. The self-luminous paste materials are prepared by adding long afterglow rare earth luminescent powder and glass beads reflective powder into cement materials. The luminescence properties are characterized by afterglow decay time and fluorescence chromatography. The optimum range of particle size of self-luminous pavement materials and reflective powder is determined, which can provide reference for the further research. As for the self-regulation pavement material, the thermogravimetric and differential scanning calorimetry tests are conducted to study the thermal stability and phase transition characteristics of PEG. The results show that PEG has excellent thermal stability; the average molecular weight ranging from 4000 to 10000 of PEG have relatively high phase change heat storage capacity and similar phase change temperature. Based on asphalt properties, the optimum average molecular weight for asphalt pavements can be further decided. Conductive asphalt mixtures are used in this study to investigate the self-healing properties under microwave irradiation. The microstructure and element distribution of steel slag are characterized through scanning electron microscope. The healing level and the optimum content of steel slag are evaluated according to the recovery strength level of steel slag asphalt mixture and the surface temperature distribution of specimen under microwave radiation. Results show that steel slag is an excellent microwave absorbing material, which can effectively improve the healing level of the mixture, meanwhile, there is an optimal addition amount of the steel slag. The significance of innovative material design is not only related to expanding the pavement functions, but also to bolstering the structural technology design concepts of modern road engineering as well as to offering new technologies for the related industry sector.

A parallel differential confocal method (PDCM) is proposed to obtain rapid surface height measurements with nanoscale precision with a conventional optical microscope. In contrast to existing differential surface profiling methods where multiple sensors are required and either pixel-by-pixel horizontal or layer-by-layer vertical scanning is necessary, the PDCM uses only a single sensor without scanning. It uses parallel pinholes to generate confocal images Ia and Ib at an equal distance but in opposite directions away from the focal plane. Then the method generates differential intensity signals by subtracting these two images, and then employs these signals to determine the heights of the object surface based on precalibrated curves. The precision and relative standard error of the proposed method were 1 nm and ≤ 0.2%, respectively. Its efficiency was 13 fps for $2018 \times 512$ horizontal locations. Due to its advantages in efficiency and precision, it can be considered as one of the ideal online surface height profiling methods for industrial metrological applications.

In this study, a multi-functional sandwich structure is proposed with mechanical support, electromagnetic radiation and absorption by radome-integrated design of metamaterial antenna array. The pyramid metamaterial absorber (PMA) is used as the radiator of the antenna element, with a fibre-reinforced resin composite radome attached on the top. To enhance mechanical strength of the radome and meanwhile to reduce radar cross-section (RCS) of the antenna, the PMA is used as the lattice core of sandwich structure. By engineering the dispersion, the PMA structure is used as low-loss antenna in-band radiator and broadband out-of-band absorber simultaneously. For instance, an antenna working in the C-band and with RCS reduction in the X-band was designed, manufactured and measured. Radiation performances of the antenna are verified. A 5 × 5 antenna array and a 2 × 2 array were also fabricated to evaluate the absorption and mechanical properties, respectively. Measured results of the 5 × 5 array present that the RCS reduction is more than 20 dB in the X-band. Quasi-static out-of-plane compression tests on the 2 × 2 antenna array verify the good mechanical performances. The sandwich structure can achieve high mechanical strength, good radiation performance and low RCS, which provides a new paradigm of antenna–radome-integrated design for practical applications.

As the problem of asphalt concrete bridge deck pavement is becoming more and more serious, how to improve its road performance has become the focus of the study. As the lack of shear strength and bond strength between layers, flaking, raveling and other diseases were occurred on steel bridge deck asphalt pavement. This paper combines the common damages of bridge deck and asphalt concrete pavement in cold area of northeast region, focuses on the analysis of the cause of asphalt concrete pavement damage causes, puts forward preventive measures and recommendations, and present the bridge deck pavement structure in cold area combined with the engineering practice. The research results can effectively guide the construction of bridge deck pavement.

A particular nanosized alumina (α-Al2O3) filler reduces the wear rate of polytetrafluoroethylene (PTFE) by nearly 4 orders of magnitude in ambient environments through the formation of stable interfacial tribofilms. One key to the unusual success of this system is the tribochemical degradation of the polymer and subsequent formation of carboxylate salts, which directly bond the PTFE to both the alumina nanofiller and the metallic counterface. However, previous studies have shown that the exceptional wear resistance of these cross-linked, stable, and well-anchored surfaces vanishes when slid against surfaces of slightly higher surface energy. In this paper, we elucidate the effects of these interfacial gradients within the native ultralow wear composite-on-transfer film system using interrupted wear tests and intermittent surface analysis. As anticipated, the transition from high wear to ultralow wear was accompanied by small adherent debris, tribochemical formation of carboxylates, increased surface energy, and increased adhesion. Interestingly, we observed significant differences on either side of the interface during low wear sliding; compared to the running films on the composite surface, the transfer films on the counterface exhibited consistently greater tribochemical degradation, surface energy, and adhesion to a model alumina probe. This interfacial gradient, we propose, is a necessary feature of the ultralow wear system and functions by setting the direction and driving force for transfer wear. In this case, the interfacial gradient stabilizes the transfer film and minimizes the driving force for running film wear.

Self-healing materials (SHMs) with unique mechanical and electronic properties are promising for self-reparable electronics and robots. However, the self-healing ability of emerging two-dimensional (2D) materials, for instance, MXenes, has not been systematically investigated, which limits their applications in self-healing electronics. Herein, we report the homogeneous self-healing assembly (homo-SHA) of MXene and the heterogeneous self-healing assembly (hetero-SHA) of MXene and graphene oxide (GO) under moisture treatments. The self-healing mechanism has been attributed to the hydration induced interlayer swelling of MXene and GO and the recombination of hydrogen bond networks after water desorption. The multiform hetero-SHA of MXene and GO not only enables facile fabrication of free-standing soft electronics and robots, but also endows the resultant devices with damage-healing properties. As proof-of-concept demonstrations, free-standing soft electronic devices including a generator, a humidity sensor, a pressure sensor, and several robotic devices have been fabricated. The hetero-SHA of MXene and GO is simple yet effective, it may pioneer a new avenue to develop miniature soft electronics and robots based on 2D materials.

Transient liquid phase (TLP) bonding was applied to prepare Cu/In-Sn-xAg/Cu (x = 20, 30, 40, 50, 60, 70 wt%) solder joints, and the effect of Ag particle content on joint microstructure, shear property and growth mechanism of intermetallic compound (IMC) was studied. The results indicated that the microstructure of solder joint consists of interfacial diffusion reaction zone and particle in situ reaction zone. The IMC in interfacial diffusion reaction zone is Cu3(In, Sn) phase and the IMCs in in situ reaction zone is composed of In-rich phase + Ag particle + ζ-Ag3In + Ag3(In, Sn). With the increasing Ag particle content, the thickness of IMC layer in diffusion reaction zone is decreased, the total amount of In-rich phase and Ag3(In, Sn) phase in in situ reaction zone is decreased, the quantity of Ag particles and ζ-Ag3In phase is grew. The AgIn2 phase is a stable IMC formed as a preferential reaction because it requires less Gibbs free energy than Sn-Ag phase, and it is transformed to ζ-Ag3In phase with increasing bonding time to 10 min. The void ratio of solder joints is decreased firstly and then increased with increasing Ag content. The shear strength of the joint is increased firstly and then decreased with increasing Ag particle content, and the maximum shear strength 22.2 MPa is obtained by Cu/In-Sn-50Ag/Cu solder joints. The shear fracture mechanism of solder joints is changed from ductile–brittle mixed fracture to brittle fracture.

Knowledge of transport phenomena and keyhole evolution is important for controlling laser welding process. However, it is still not well understood by far due to the complex phenomena occurring in a wide temperature range. A transient 3D model including heat transfer, fluid flow and tracking of free surface is built in this study. The transport phenomena are investigated by calculating the temperature and velocity fields. The 3D dynamic keyhole evolution process is revealed through tracking free surface using volume-of-fluid method. The results show that the keyhole deepening speed decreases with laser welding process before the quasi-steady state is reached. The plasma can greatly affect the keyhole depth through absorbing a great amount of laser energy and thus lowering the recoil pressure. Moreover, the relationship between keyhole depth and weld penetration is also discussed. This paper can help to better understand the dynamics in molten pool and then improve laser welding process.

The accumulated stock of coal fly ash becomes more and more huge nowadays, and it could result in severe environmental issues. Therefore, developing a facile and environment-friendly approach to dispose the coal fly ash is highly desirable. Herein, a novel process combining a traditional acid roasting treatment and a pre-desilication process by roasting is proposed to efficiently and eco-friendly recycle alumina from coal fly ash. Because of the differences in alkali-digestion properties of alumina and silicon dioxide, the aluminum sulfate was decomposed into alumina, and amorphous alumina transformed into γ-alumina with the increase of temperature during phase transformation roasting process, while the alkali-digestion property of alumina declined. However, the alkali-digestion property of silicon dioxide in calcines was unchanged with the increase of roasting temperature during roasting process. The digestion ratio of silicon dioxide and alumina were 73% and 0.78%, respectively, under the phase transformation roasting conditions of 950 °C and 60 min. This research established foundation for further desilication studies. The digestion ratio of silicon dioxide could be improved by optimizing digestion parameters and the alumina could be recovery from digestion residue by Bayer process. This proposed process here could give an industrial guideline for recovery of alumina from coal fly ash.

The isothermal compression tests for as-homogenized Mg–5.8 Zn–0.5 Zr–1.0 Yb magnesium alloy were performed on a Gleeble-1500 thermo-mechanical simulator at the temperatures of 250, 300, 350 and 400 °C and the strain rates of 0.001, 0.01, 0.1 and 1 s−1. The progress of dynamic recrystallization (DRX) was modeled by the modified Avrami type equation and the DRX kinetics was expressed as a function of the Zener-Hollomon (Z) parameter. The effects of the Z parameter on the microstructure evolution, the DRX fraction, the DRX rate, and the DRX sensitive rate were analyzed. An iso-fraction contour map was proposed to clarify the relations among the Z parameter, DRX fraction and deformation degree. Based on the spacing between the contours, the partial DRX stage was divided into three successive sub-stages and each of them was characterized by the mechanism underlying DRX evolution. Moreover, the ZK60 (Yb-free) alloy was adopted for comparative analysis to elucidate the effect of Yb addition on the DRX kinetics. The results showed that the Z parameter exerted a fundamental influence on the DRX evolution. Considering the robustness and efficiency of DRX, the deformation regime with the lnZ value less than 24 was preferable. Furthermore, the Yb addition can promote the onset of DRX but the progress should be retarded to some extent compared with the Yb-free counterpart. These conclusions were verified by the microstructure observations.

In order to reduce energy consumption and further improve the performance of viscose yarns, this study introduced a collaborative control method to improve spun yarn performance by contacting the spinning strand with both a softening device and a pressure plate. In this study, we analyze the improving mechanism of spun yarn performance using the softening device and pressure plate. The results show that thermal insulation layer formed between the softening device and pressure plate could heat the yarns in all directions to further re-wrap out-exposed hairiness into the main body of yarns and save energy consumption. Four groups of 19.7 tex viscose yarns were spun with different collaborative apparatus (with and without the softening device or pressure plate). Four groups of viscose yarns were tested in terms of hairiness, unevenness, and tensile property. Moreover, the experimental results show that collaborative apparatus with the softening device and pressure plate could significantly improve yarn performance, including CV value, hairiness, break elongation, and breaking strength to 11.3%, 18.94, 12.9%, and 311.0 cN, respectively.

Shape-programmed deformation of soft polymer films is essential for applications in robotics, self-adaptive devices, and sensors. In comparison to bilayer polymer actuators, the challenge remains to manipulate single-layered soft actuators for rapid, reversible, and shape-programmed deformations in response to external stimuli owing to their homogeneous composite structures. Herein, this work reports a soft polymer film actuator that has a single-layered structure, yet demonstrates the shape-programmed motility. The actuator is composed of polyvinylidene fluoride film as a matrix and patterned by photocrosslinking of acrylamide and N', N'-methylenebisacrylamide, which generates soft-hard alternating segments in the structure. As it is exposed to acetone vapors, the soft-hard structures lead to an unequal response that results in the shape-programmed deformation. The actuator is elastic (strain: 160%) and tough (stress: 40 MPa) and can maintain its rapid, reversible, and shape-programmed motions for a few hours, even longer. The soft-hard structure enables the film actuator (3.5 mg) to give a contracting stress of 4 MPa that is used in an automatic device able to lift a cargo of 5.09 g, ∼1453 times heavier than the film itself. The power output reaches 474 J kg-1, ∼100 times higher than the reported soft actuators. This simple application indicates a potential for the soft actuator used in acetone vapor sensing devices.

Stable functional surfaces with reversibly switchable wettability have recently been developed for the continuous separation of oil–water mixtures. This article proposes a facile method to fabricate superhydrophobic surfaces on copper meshes by combining poly(dimethylsiloxane) and graphene. The superhydrophobic surface can dramatically switch to a superhydrophilic state under O2 plasma etching and recover to a superhydrophobic state after laser etching to achieve unidirectional transport of oil or water. The surface had a high separation efficiency and favorable reusability in oil–water separation. In addition, the superhydrophobic surfaces demonstrated not only outstanding stability, including an anticorrosion ability, anti-UV exposure ability, oil contamination resistance, and abrasion resistance, but also an excellent self-healing ability after flame treatment. This research opens a novel avenue for the design of stable materials with reversible wettability that may have promising potential application...

Using Aspen Plus simulation software to simulate the hydrogen solubility of white oil raw materials, and calculate the de-aromatic hydrogen consumption. The liquid hydrogenation technology of white oil was studied by using 100mL uplink liquid hydrogenation evaluation device. The research results show that the ultraviolet absorbance of the liquid phase hydrogenation product is no more than 0.1, and saybolt color, copper plate corrosion, readily carbonizable substance can meet the quality requirements under the conditions of 230℃, 17 Mpa and LHSV 0.5 h-1. 2000 hours liquid phase hydrogenation test shows the stability of product quality which meets the food grade standard, and the liquid phase hydrogenation technology is feasible.

Solid-state thermo-stamping of fabric reinforced composites has attracted extensive attention for its efficiency and potential energy saving in recent years. In this paper, a hybrid lamination model is proposed to describe the forming behavior of woven fabric reinforced thermoplastic composites (WFRTP) during solid-state thermo-stamping process. The woven carbon fiber (CF)/ Polyetheretherketone (PEEK) sheet/prepreg is modelled as laminate structure with woven reinforcement layers (shell elements) embedded in thermoplastic resin layer (solid elements). More specifically, a hypoelastic constitutive model is used to represent the anisotropic mechanical behavior of fabric reinforcement under large deformation, while the fabric model is calibrated and validated by uniaxial bias extension (UBE) test and tensile test of woven fabric. A phenomenological model is adopted to describe the viscoelastic-plastic deformation behavior of thermoplastic resin, while the resin model is calibrated by tensile tests of PEEK. The applicability of the hybrid model is demonstrated through comparing numerical results of UBE tests and Erichsen tests with their corresponding experiment results. The hybrid lamination model provides a theoretical foundation for numerical simulation of WFRTP solid-state thermo-stamping.

Durability, or sometimes called lifetime of fuel cell stack, is the prime parameter of the polymer electrolyte exchange membrane fuel cell (PEMFC) electrical vehicles. Vehicle operations include some driving state which will affect the output behavior of fuel cell stack. Some key driving states are analyzed, and they have significant effects on the durability of PEMFC stacks. Released durability test protocols are reviewed and compared from based on these key driving states. These durability test protocols can be good references on evaluation of fuel cell stack and development of the fuel cell electrical vehicle (FCEV).

A reforming prehydrogenation catalyst suitable for blending inferior coking gasoline was developed by the supporter modification, selection and optimization of active component. The catalyst has high performance of hydrodesulfurization, hydrodenitrification and olefin saturation at low temperature. The catalyst has good activity and strong adaptability to raw materials, At reaction pressure of 2.0MPa, hydrogen-oil volume ratio of 200:1, LHSV of 5.0h-1, reaction temperature of 268-280℃, it can process the prehydrogenation raw materials blending inferior hydrocoking gasoline (20-50%), and the generated oil can meet the requirements of reforming feed. The results of 1500h activity stability test show that the catalyst has excellent activity stability.

a multilayer SIW (Substrate Integrated Waveguide) filter on glass substrates has been designed, fabricated and measured for potential utilization in advanced 3D packaging applications. Specifically, the SIW topology is chosen to use the top and bottom metal cover of the SIW cavities as the gold-to-gold bonding surfaces. The direct bonding serves as the electrical and mechanical connections at the same time. The fabricated filter operates at X band and the insertion loss is about 2.2 dB with the return loss better than 15dB. In addition, the fabrication is fully compatible with the conventional thin film fabrication process. In this article, the filter's design, fabrication process and the measurements are reported.

The surface wettability of plants exhibits many unique advantages, which enhances the environmental adaptability of plants. In view of the rapid development of responsive materials, smart surfaces have been explored extensively to regulate surface wettability through external stimuli. Herein, we summarized recent advancements in bioinspired surfaces with switchable wettability. Typical bioinspired surfaces with switchable wettability and their emerging applications have been reviewed. In the end, we have discussed the remaining challenges and provided perspective on future development.

Surface-enhanced Raman scattering (SERS) is highly promising for ultra-sensitive detection in a series of applications. Although extensive advances have been achieved in SERS technologies, the preparation of highly efficient SERS substrates still suffers from several limitations, including complex preparation procedures, high cost, and instability for long time storage. To address these problems, we report a novel, to the best of our knowledge, SERS platform that combines graphene oxide (GO) and cellulose composite paper with colloidal silver nanoparticle (Ag NP) ink. As an efficient substrate, the GO and cellulose composite paper that features hierarchical micro-nanostructures and improved interaction with target molecules can be fabricated on a large scale, and the Ag NP ink can be well stored, avoiding being oxidized in ambient conditions. In this way, our SERS platform not only reduces the cost, but also improved the stability. The sensitivity, reproducibility, and tunable SERS detection performance were evaluated using rhodamine 6G as probing molecules. To demonstrate the capability of our SERS platform in practical analysis, the SERS spectra of two monosodium salt solutions of different concentrations have been collected. The SERS platform has revealed great potential for practical application of SERS technologies.

To improve the life of the meshing pair in single screw compressor (SSC), several meshing pair profiles (MPP) were proposed for raising the lubrication properties. Therefore, it is necessary to evaluate the lubrication performance of the MPPs. In this paper, an evaluation method based on micro deflecting motion trajectory (MDMT) is proposed and the theoretical model to realize MDMT is established. The model mainly contains a geometric model, a thermodynamics model, a hydrodynamic lubrication model and corresponding algorithm. With the presented method, three kinds of MPP including single straight line type (SSLT), single column type (SCT) and multi column type (MCT) have been analyzed. Obtained results show that compared to the SSLT and SCT, the MCT generates the greatest peak value of the water film pressure. The total torque applied on the gate-rotor generated by the water films decreases with the increment of the discharge pressure and increases with the machine size. The water film stiffness firstly decreases and then increases with the micro deflecting angle increasing. The water film stiffness at trailing side is always larger than that at leading side. As the discharge pressure increases, the MDMT curves approach the leading flank, and the lubrication properties get worse. With the machine size increasing, the MDMT curves move towards the trailing side and the lubrication performance is improved. Comparing to the other two MPPs, the MCT can achieve floating mesh without contact in relatively larger machines and comparably lower discharge pressure.

Squeeze film force exists but is undesirable in some engineering applications such as immersion lithography and micro-electro mechanical systems. The dynamic characteristics of such systems can be improved by adopting hydrophobic surfaces. In addition to squeeze film damping effects, slip effects are prominent and the inertial effects can be neglected with small film thickness, while inertial effects are prominent and slip effects can be neglected with large film thickness. Existing squeeze film force models that ignore inertia effects will cause unacceptable deviations between hydrophobic surfaces with clearance from dozens to hundreds of microns. In this paper, the squeeze film force model is formulated based on Navier–Stokes equations and two parameters slip boundary conditions while simultaneously considering slip and inertia effects. Experiments using different squeeze film thicknesses and squeeze amplitudes are conducted with parallelism between two specimen surfaces of less than 0.01°. The experimental results show that the slip and inertia effects are critical for accurately predicting the squeeze film force between hydrophobic surfaces under moderate film thickness. The predicted errors of the proposed model can be significantly reduced to less than 0.5% after proper fitting of the two slip parameters under all the test conditions. The method can be adopted for the identification of slip parameters and derivation of kinetic models for systems with squeeze film.

Bioresorbable polymeric stents have attracted great interest for coronary artery disease because they can provide mechanical support first and then disappear within a desired time period. The conventional manufacturing process is laser cutting, and generally they are fabricated from tubular prototypes produced by injection molding or melt extrusion. The aim of this study is to fabricate and characterize a novel bioresorbable polymeric stent for treatment of coronary artery disease. Polycaprolactone (PCL) is investigated as suitable material for biomedical stents. A rotary 3D printing method is developed to fabricate the polymeric stents. Surface modification of polymeric stent is performed by immobilization of 2-N, 6-O-sulfated chitosan (26SCS). Physical and chemical characterization results showed that the surface microstructure of 3D-pinted PCL stents can be influenced by 26SCS modification, but no significant difference was observed for their mechanical behavior. Biocompatibility assessment results indicated that PCL and S-PCL stents possess good compatibility with blood and cells, and 26SCS modification can enhance cell proliferation. These results suggest that 3D printed PCL stent can be a potential candidate for coronary artery disease by modification of sulfated chitosan (CS).

Solar interfacial evaporation has been recognized as a versatile energy conversion protocol for cutting-edge applications such as water treatment and power generation (e.g., hydro voltaic effect). Recently, to enhance water evaporation rates, water temperature and evaporation area have been considered as essential ingredients, and thus photothermal materials and three-dimensional hierarchical structures have been developed to promote light-to-heat conversion efficiency and enhance interfacial evaporation. However, less attention has been paid to the airflow effect, because the interfacial floatability of photothermal membranes should be considered under air blast. Here, inspired from the stable interfacial floatability of lotus leaves, we report the airflow enhanced solar interfacial evaporation approach using a graphene-based Janus membrane. Laser-induced graphene (LIG) film was treated unilaterally by O2 plasma, forming a LIG/oxidized LIG (LIG-O) Janus membrane with distinct wettability on two sides. Higher water evaporation rate of 1.512 kg m-2 h-1 is achieved. The high solar interfacial evaporation performance can be attributed to the two advantages: (i) the combination of microscale capillary water transporting and nanoscale light trapping; (ii) hydrophobic/hydrophilic Janus membrane for stable interfacial floatability under airflow. Our approach is feasible for developing high-performance solar interfacial evaporation devices for practical clean energy utilization.

Isothermal compression tests at temperatures of 250–400°C and strain rates of 0.001–1 s−1 were performed in a Gleeble-1500 thermal simulator to investigate the hot deformation behavior of as-homogenized Mg-5.8 Zn-0.5 Zr-1.0 Yb alloy. The Arrhenius-type constitutive equation and hot processing maps were established based on these experiments. Two dynamic recrystallized (DRX) domains were identified as (1) 280–350°C and 0.15–1 s−1; (2) 330–400°C and 0.001–0.09 s−1. The DRX mechanisms of the above-mentioned two domains and the instability patterns of the unstable regions were analyzed by optical microscopy and electron backscatter diffraction. The results provide a fundamental insight into the processing design, microstructural evolution, and property control of the newly developed Mg-Zn-Zr-Yb alloy.

A high-quality brake material was developed by using different rare earth oxide modified resin-based brake materials and designing the composite material through an orthogonal optimization test. Th...

Moisture-responsive actuators based on graphene oxide (GO) have attracted intensive research interest in recent years. However, current GO actuators suffer from low mechanical strength. Inspired by the robustness of nacre's structure, moisture-responsive actuators with high mechanical strength and self-healing properties were successfully developed based on GO and cellulose fiber (CF) hybrids. The hybrid paper demonstrated significantly improved tensile strength, ∼20 times higher than that of pure GO paper, and self-healing properties. A broken paper can be well cured under moist conditions, and the mechanical properties of the self-healed hybrid paper can still maintain similar tensile strength to the pristine one. After controllable ultraviolet light photoreduction treatment, a hybrid paper with a photoreduction gradient along the normal direction was prepared, which can act as a moisture-responsive actuator. A maximum bending curvature of ∼1.48 cm-1 can be achieved under high relative humidity (RH = 97%). As a proof-of-concept, a butterfly-like actuator that can deform itself with moisture actuation was demonstrated. Our approach may pave a new way for designing robust and self-healable graphene actuators.

A new electron-rich central core (BTT) based on benzo[1,2-b:4,5-b′]dithiophene with a thio[3,2-b]thiophene side chain was coupled with methyl and fluorine-modified 1,1-dicyanomethylene-3-indanone (IC) electron-withdrawing end groups to furnish two novel non-fullerene acceptors (NFAs), namely BTT-MIC and BTT-FIC. Compared to BTT-MIC, BTT-FIC exhibits a stronger near-infrared (NIR) absorption with a smaller optical bandgap (1.47 eV). The BTT-FIC/PM6 based device achieved a champion PCE of 12.65% for benzo[1,2-b:4,5-b′]di(cyclopenta[2,1-b:3,4-b′]dithiophene)-containing NFA based organic solar cells (OSCs), while the BTT-FIC/PM6 based device delivered a PCE of 10.04% with a high Voc of over 1 V. Fluorinated IC is more suitable for this new core BTT than methyl substituted IC, because fluorine atoms enhance the charge transport (CT) state (absorption) and are also beneficial to exciton dissociation, charge mobility and morphology. This work revealed that BTT with a thieno[3,2-b]thiophene side chain is an effective electron-donating core for creating effective NFAs and fluorinated IC is a suitable end group for BTT.

The amalgamation of thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) properties, term AIE-TADF, is a promising strategy to design novel robust luminescent materials. Herein, we transform 2,3,4,5,6-penta(9H-carbazol-9-yl)benzonitrile (5CzBN) from an ACQ molecule to AIEgens by simply decorating a 5CzBN core with alkyl chain-linked spirobifluorene dendrons. By increasing the number of flexible dendrons, these materials can not only show obvious AIE-TADF characteristics and uniform film morphology, but also exhibit better resistance to isopropyl alcohol, which are beneficial to the fully solution-processed OLEDs. Notably, 5CzBN-PSP show great device efficiency with external quantum efficiency (EQE), current efficiency and power efficiency of 20.1%, 58.7 cd A-1 and 46.2 lm W-1, respectively, which achieved record-breaking efficiency in solution-processed nondoped OLEDs based on AIE emitters. It demonstrates a general approach to explore new efficient emitters by the marriage of AIE and TADF what could potentially improve their performance in various areas.

In startup process of steam turbine in nuclear power plant, undue deformation of gland seal (GS) may cause rubbing fault. Due to small gland seal clearance, modern advanced steam turbine requires precise control of gland seal deformation (GSD). In line with the above mentioned situations, firstly, a comparison study to reveal GSD behavior on low pressure (LP) casing of a 1000 MW nuclear steam turbine was carried out in startup process by using thermo-mechanical coupling method. The most serious condition for GSD was found out. Further, sensitivity analysis of GSD was conducted. The influence of back pressure and temperature of GS and bearing on GSD during vacuuming (VA) were researched. Finally, to evaluate the risk of rubbing fault, a formula for predicting the bottom clearance of GS during VA was proposed. The results indicate that, in startup process, the GS moves up significantly during VA. The calculated data are in good agreement with on-site measurements. The temperature rise of exhaust hood, which is influenced by GS temperature, makes the GS to lift up. The GS temperature is the most sensitive factor affecting GSD during VA. Rubbing fault may occur when the temperature of GS reaches 112 °C during VA. The results of this research has been used as a guidance for analyzing and improving operational reliability of steam turbine in nuclear power plants.

The effect of aging temperature on microstructure and mechanical properties of Sn–9Zn–xZrC (x = 0, 0.06) solder joints was investigated. The results showed that the wettability of Sn–9Zn based alloys was improved by ZrC nanoparticles, the spreading areas of Sn–9Zn–xZrC (x = 0–0.12) were increased firstly then decreased with increasing ZrC content. The spreading area of Sn–9Zn was about 143.64 mm2 and reached maximum about 190.92 mm2 of Sn–9Zn–0.06ZrC. The microstructure of Sn–9Zn–0.06ZrC solder alloy consisted of β-Sn, Sn–Zn eutectic and intermetallic compounds (IMCs), and the microstructure of Sn–9Zn alloy was refined by adding appropriate amounts of ZrC nanoparticles. The interfacial IMCs at the β-Sn boundary in the Sn–9Zn–0.06ZrC solder joint was Cu5Zn8, and partial Cu5Zn8 was transformed to Cu6Sn5 during aging treatment. The IMCs layer thickness was dominated by aging temperature, and ZrC facilitated the IMCs layer growth. The tensile strength of Sn–9Zn based solder joints was enhanced by adding ZrC particles, and then are decreased simultaneously with increasing aging temperature. The fracture surface of Sn–9Zn joints after aging was mainly composed of uniform dimples, and the fracture mechanism of Sn–9Zn based solder joints was ductile fracture.

In the natural evolution, animals and plants have evolved many unique structures and properties. For example, butterfly wings appear to be colorful due to grating structures. Lotus leaves have super-hydrophobic property because of micro/ nano-structures. Nepenthes pitcher plants show slippery wettability by reason of the lubricant infused surfaces. Therefore, more and more researchers are trying to prepare unique structures which are similar to the surface of biological templates by different methods. Taking superhydrophobic surfaces as an example, there are many methods having been adopted to achieve superhydrophobic surfaces, such as etching, template method, UV lithography, electrostatic spinning, and nano-imprint technique. In recent years, laser processing technique has the advantages of high precision and arbitrary design, which shows great advantages in bionic manufacturing. For example, various kinds of micro/nano composites or structures have been successfully prepared by laser direct writing, two/four-beam interference, etc. However, these methods rely mainly on complex or sophisticated instruments, which take long time to prepare large-area superhydrophobic surfaces. Reed leaves show anisotropic superhydrophilicity property because of grating structures, which has applications in droplet transmission without loss and directional collection. Herein, we demonstrated the fabrication of bionic reed leaf by laser treatment of structured polydimethylsiloxane (PDMS) surface. Laser treatment of PDMS with micro-grating structures can induce the micro-nano structures and improve the surface roughness. To investigate the change of surface chemical composition, we carried out X-ray photoelectron spectroscopy (XPS) of PDMS before and after the laser treatment. After the laser treatment, the carbon content was decreased from 43.6% to 33.1%. The decrease in carbon content indicates the emission of carbon material during laser treatment, which is caused by the carbonization of the methyl group on the surface of the PDMS. At the same time, the oxygen content increased from 27.8% to 33.6% and the silicon content increased from 28.3% to 33.3%. To compare the surface morphologies changes of PDMS before and after laser treatment, we observed the surface morphology by confocal laser scanning microscopy (CLSM) and scanning electron microscope (SEM). The initial PDMS grating is about 100 μm wide, ~130 μm high and the structure surface is smooth. After laser treatment, it changes to about 200 μm wide, ~110 μm high and becomes much rougher surface. The variation in the width and height is mainly because that the laser treatment causes PDMS surface material to carbonize into rough structures. In order to evaluate the wettability changes of samples, the static water contact angle and dynamic water sliding angle measurement was carried out on the flat PDMS, the structured PDMS, and the laser-treated structured PDMS, respectively. The contact angle along the parallel direction was ∼155°, which is larger than that along the vertical direction (~150°). The sliding angle along the parallel direction was approximately 3°, which was smaller than the SA along the vertical direction (12°). This method provides a new idea for preparation of superhydrophobic surfaces with bionic structures by laser technology. The method is simple, convenient, and low cost, which may become a general method for preparing superhydrophobic surface.

CoCrMo alloy is widely used in the medical field to make Biomedical prosthesis,But it is difficult to process resulting in the high cost of Biomedical prosthesis, Find an efficient and low-cost processing method has become a problem to be solved. In this paper, CoCrMo alloy Biomedical prosthesis were fabricated by Electrolytic In-process Dressing grinding. We studied the ELID grinding performance, grinding force, surface quality and the formation mechanism of Corrosion-resistant oxide layer of CoCrMo alloy by using dynamometer, roughness tester, XRD and SEM. It is proposed that the ELID grinding method forms an oxide layer on the surface of the prosthesis, which increases the corrosion resistance and biocompatibility of the prosthesis so that it can be better adapt to the biological environment in vivo. It was further confirmed that the ELID grinding method is an effective method for manufacturing CoCrMo Alloy Bioprosthesis.

Natural graphite is investigated as the cathode for aluminum ion batteries in recent years. However, some drawbacks of the natural graphite such as severe volume swelling shorten its lifetime. In this work, we prepared a composite material by depositing an amorphous carbon on the graphite paper. The composite was used as a cathode to study the electrochemical performance in aluminum ion batteries. The charge/discharge results showed that the composite could exhibit a longer cycle life than the graphite paper. Electrochemical analyses demonstrated that the interface between the amorphous carbon and the graphite paper made a major contribution to the improvement of the cycling stability.

Van der Waals (vdW) crystals with covalently bonded building blocks assembled together through vdW interactions have attracted tremendous attention recently because of their interesting properties and promising applications. Compared to the explosive research on two-dimensional (2D) vdW materials, quasi-one-dimensional (quasi-1D) vdW crystals have received considerably less attention, while they also present rich physics and engineering implications. Here we report on the thermal conductivity of exfoliated quasi-1D Ta2Pd3Se8 vdW nanowires. Interestingly, even though the interatomic interactions along each molecular chain are much stronger than the interchain vdW interactions, the measured thermal conductivity still demonstrates a clear dependence on the cross-sectional size up to >110 nm. The results also reveal that partial ballistic phonon transport can persist over 13 μm at room temperature along the molecular chain direction, the longest experimentally observed ballistic transport distance with observ...

A shrouded oscillating-foil turbine is proposed to augment the energy extraction performance. The oscillating foil undergoes combined plunging and pitching motion to convert the flow energy. A diffuser is introduced into the oscillating-foil-based turbine as the shroud. The speed-up and energy extraction performance of the turbine were assessed numerically. The effects of three cost-independent geometrical factors, namely shroud entrance width, shroud angle and streamwise distance between shroud and foil, and shroud sectional shape on energy extraction performance were investigated in detail. The optimal motion parameters for the shrouded oscillating-foil turbine were re-explored due to the altered flow field in the shroud. The results demonstrated that the maximum energy extraction efficiency of bare oscillating foil (0.336) can be augmented by 35.8% to 0.456 by appropriate arrangement of the shroud with a relative chord length of 0.8. The optimal motion parameters for the shrouded foil are slightly different from those of bare foil. The re-tuned motion parameters can further improve the efficiency to 0.47. Considering both the manufacturing cost of the shaped sections and their performance, it is more advantageous and attractive to use a flat plate as the shroud in engineering practices.

The corrosion resistance of Zr alloys tightly connects to the oxide films on Zr alloys. We use first-principles computational tensile test to perform a systematical investigation on the tensile strain–stress behaviors of monoclinic zirconia, and reveal the formation mechanism of initial pores and cracks in the oxide films. Based on calculated results, we propose a new mechanism of initiation of pores in the oxide films, which has solved the puzzle of pore formation at oxide/metal (O/M) interface of pure Zr. Moreover, our results are also well consistent with many previous microstructure characterization results of Zr alloys.

We theoretically provide a magnetic phase diagram for the single-layer (SL) CrBr3, which could be effectively tuned by both strain engineering and charge doping in SL-CrBr3. Through systematical first-principles calculations and Heisenberg model Hamiltonian simulations, three different magnetic phases in SL-CrBr3, which are off-plane ferromagnetic, in-plane ferromagnetic and in-plane Néel-antiferromagnetic phases, are found in the strain and charge doping regimes we studied. Furthermore, our results show that higher order Heisenberg exchange parameters and anisotropy exchange parameters should be taken into account for accurately illustrating the magnetic phase transition in SL-CrBr3. As a result, we find from the SpinW simulation that the Curie temperature is about T c = 38.4 K, which is well consistent with the experimental result 34 K [Nano Lett. 19 3138 (2019)]. The findings here may be confirmed in future experiments, and may be useful for the potential applications of SL-CrBr3 in spintronics field.

Electrochemical analysis using specifically designed electrodes represents a promising strategy to detect organic pollutants, such as 4-nitrophenol (4-NP), in the environment. Towards this goal, a metal-free composite of phenanthroline doped graphitic carbon nitride (g-C3N4-PD) was synthesized, characterized, and applied as the electrode materials for electrochemical detection of 4-NP in water. The phenanthroline doping simultaneously extends the π-conjugation system of g-C3N4, and creates defect sites in g-C3N4, leading to better conductivity, higher 4-NP adsorption, and significantly enhanced electrocatalytic activity. Electrochemical sensors were fabricated by using g-C3N4-PD-modified carbon electrode. They showed a broad detection concentration range of 2.854–1117 μM and a low detection limit of 39 nM for 4-NP, with high reproducibility, stability and selectivity. Reliable and accurate measurements of 4-NP in real-life water samples have been demonstrated using these electrodes.

Dialkyl dithiophosphate ester (DDPE) used as an extreme pressure/antiwear (EP/AW) additive in mineral base oil (BO) was introduced to a steel–aluminum contact in this study. The tribological perfor...

A smart bilayer of AG@CNT/AG composed of carbon nanotubes (CNTs) and agarose (AG) is developed. TiO2 patterns which partly reflect light are introduced at the bilayer surface, giving rise to a spatially selective photothermal effect that can be used to induce shape-programmed motility upon light irradiation. The TiO2 patterns also result in the bilayer with a differential flexural modulus and can thus modulate its motility induced by humidity.