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The adsorption and recovery of dysprosium ions (Dy3+) from industrial wastewater are necessary but still challenging. Herein, we constructed a series of defect-containing metal-organic frameworks (MOFs) [UiO-66-(COOH)2] using sodium benzoate (BCNa) as a modulator. Upon the formation of defects, the porosity and surface charge properties of the MOFs were improved, leading to a higher utilization ratio of active groups and higher adsorption capacities for Dy3+. The synthesized UiO-66-(COOH)2-B10 with an optimal addition of BCNa exhibited a superior adsorption capacity of 150.6 mg g-1. Fast adsorption occurred at ∼5 min, and equilibrium was reached at ∼60 min. Higher pH and temperature were found to be beneficial for boosting Dy3+ adsorption, and selective adsorption over other metal ions was achieved in a multicomponent solution. Further, FTIR spectroscopy and XPS investigations indicate that free carboxyl contributes to the capture of Dy3+. Thus, this work provides a promising strategy to enhance the utilization ratio of active groups and further adsorption performance.

The transport property of a four-terminal MoS2NR/V7(Bz)8 device is computed within the framework of density functional theory combined with the nonequilibrium Green’s function (NEGF) technique. This device is constructed by a MoS2 nanoribbon (MoS2NR) as the source-to-drain channel and a spin-polarized V7(Bz)8 nanowire grafted on the MoS2NR surface as the double gate channel, where the four terminals are all connected to a semi-infinite one-dimensional (1D) Au lead. The transport characteristic is explored by investigating the conductance, currents, local density of states (LDOS), and scattering states. The currents of different leads are dissimilar due to the complex interplay between the four terminals that is otherwise not present in a two-terminal setup. The most interesting feature we articulate is that the induced promising properties including negative differential resistance (NDR) behavior, input/output current switching, as well as spin-polarized lead currents can be fine-tuned by the magnitude of either source bias or gate bias. These features can be utilized in designing multi-terminal nanoelectronic devices.

These years, electronic devices and integrated circuits have a trend of miniaturization and integration with the rapid development of the information industry, higher requirements have been placed on the size, purity, and defect density of silicon wafers. More urgent demands have been placed on the mass production of electronic grade polysilicon. However, the research of electronic grade polysilicon in China is still in its infancy, it is far from meeting the requirements of mass production. This paper studies the influence of the single factor of reaction temperature on the yield of silicon, the surface morphology and power consumption of polysilicon under the certain conditions, which has some reference value for the production of electronic grade polysilicon.

Titanium alloys are widely used in the aerospace industry due to their superior properties such as high strength and low density. As a new titanium alloy with higher strength and lower heat conductivity, titanium alloy TC21 is very difficult to cut and the cutting mechanism of this alloy needs to be investigated deeply. In the paper, to observe the cutting phenomenon in the turning process of TC21 alloy, a series of turning experiments have been performed to investigate the turning process of TC21 alloy. Further, the influence of some important turning parameters (cutting speed, feed speed, depth of cut and rake angle) on cutting force and chip morphology is well analyzed through the experiments. In addition, a 3D finite element model for turning was established using the software ABAQUS for helping to analyze the turning process of TC21. Through simulation, cutting force, chip formation and temperature distribution of TC21 alloy in the turning process have been achieved. At the same time, simulated cutting forces and chip morphology were compared with the results of experiment. The results of experiments showed that the chip of TC21 alloy in turning process is serrated and the rake angle of tool has the obvious effect on the chip morphology.

The electrochemical reduction of CO2 (CO2RR) can substantially contribute to the production of useful chemicals and reduction of global CO2 emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials (SZ-HCN) as CO2RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl2 was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area (1510 m2 g−g1) exhibited efficient electrocatalytic activity and selectivity for CO2RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO2-to-CO reduction with a high CO Faradaic efficiency (~93%) at −0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO2-to-CO reduction, thereby enhancing CO2RR activity.

Pitch length and surface braiding angle are two important parameters of braided composite preforms. In this paper, a method based on Faster R-CNN is proposed to measure the two parameters. First, after image acquisition, a fabric image database including initial cropped images, augmented images, and target images is established. Then, the target images are classified into four categories according to the gray change characteristics. Third, a Faster R-CNN fabric detection model is trained on the fabric image database. Fourth, targets are detected by the trained network, and corners are detected based on the detected targets. Finally, pitch lengths and surface braiding angles are measured based on the detected corners. Experimental results show that the proposed method achieves the automatic measurement of pitch lengths and surface braiding angles of 2D and 3D braided composite preforms with high accuracy.

A CMOS-integrated electrochemical biochip for high-performance molecular testing is presented. The system includes an array of 32 $\times $ 32 three-electrode voltammetry pixels and on-chip temperature control between 25 and 95 °C. Each 100 $\mu \text{m}\,\times 100\,\,\mu \text{m}$ pixel includes a CMOS-compatible and chemo-stable amorphous carbon electrode transducer connected to in-pixel $\Sigma \Delta $ current detection circuitry with 280 fA rms input-referred noise (0.1–20 Hz bandwidth) and 93 dB dynamic range (DR). Array-based DNA detection assays are implemented, and successful DNA melt-analysis and real-time label-free DNA hybridization detection are reported.

Summary Flexible viscoelastic sensors have gained significant attention in wearable devices owing to their exceptional strain-dependent electrical resistance. Most of the strain sensors are elastic composites, thus the internal stress is often preserved during the deformation when they are attached to the uneven target. Therefore, there is a pressing need for viscoelastic composites with highly self-adapted electromechanical properties sensitive to multiexternal circumstances. This work reports a liquid-metal-filled magnetorheological plastomer (LMMRP) that shows a high response behavior to the external stimulus such as magnetic field, temperature, and force. The shape-deformable LMMRP can transform from an insulator to a conductor under applying a magnetic field, thus the further viscoelastic sensor possesses a magnetic field “on-off” switch effect. The microstructure-dependent magnetic/thermal/mechanical-electrical coupling characteristics are investigated, and several proof-of-concept sensor applications, such as magnetic control, environment recognition, and motion monitoring, are demonstrated. These LMMRP composites show a broad potential in flexible sensors and soft electronics., Graphical abstract, Highlights • A shape-deformable liquid-metal-filled magnetorheological plastomer was created. • The plastomer is sensitive to magnetic field, temperature, and force. • The evolution of the particle microstructure in the plastomer was simulated. • The plastomer has great potential in flexible electronics with magnetic control., Magnetic property; Nanomaterials; Sensor

Aiming at the concavity defects in the cross-wedge rolling (CWR) process, one new rolling method named as the twice closed–open joint CWR was presented to improve the use ratio of material in CWR of the axle parts. The new rolling method included three stages: the first closed rolling, the second closed rolling and the last open rolling. To investigate the flow of material in this rolling process, one 3D finite element model (FEM) of the twice closed–open joint CWR was established. The CWR process of one pump spindle part was simulated using the established 3D FEM. The formation, the flow law of metal materials and concavity defects of end were studied. In addition, the CWR experiments were carried out. The results of simulation agreed with the results of tests well. The results proved that the new method can decrease the extent of concavity and improve the material use ratio.

This work reports an experiment/simulation combination study on the magnetorheological (MR) mechanism of magnetic fluid based on Fe3O4 hollow chains. The decrease of shear stress versus the increasing magnetic field was observed in a dilute magnetic fluid. Hollow chains exhibited a higher MR effect than pure Fe3O4 hollow nanospheres under a small magnetic field. A modified particle level simulation method including the translational and rotational motion of chains was developed to comprehend the correlation between rheological properties and microstructures. Sloping cluster-like microstructures were formed under a weak external field (24 mT), while vertical column-like microstructures were observed under a strong field (240 mT). The decrease of shear stress was due to the strong reconstruction process of microstructures and the agglomeration of chains near the boundaries. The chain morphology increased the dip angle of microstructures and thus improved the MR effect under a weak field. This advantage made Fe3O4 hollow chains to be widely applied for small and low-power devices in the biomedical field. Dimensionless viscosity as a function of the Mason number was collapsed onto linear master curves. Magnetic fluid in Poiseuille flow in a microfluidic channel was also observed and simulated. A qualitative and quantitative correspondence between simulations and experiments was obtained.

Magnetic fluid is a novel magnetorheological (MR) intelligent material consisting of magnetic particles, non-magnetic matrix, and additive agents. After applying the external magnetic field, magnetic particles will interact with each other due to the magnetic dipolar forces. The viscosity and yield stress of magnetic fluid could increase several orders of magnitude in milliseconds, which is called the MR effect. The controllable and reversible property makes magnetic fluid widely applied in drug targeting delivery, magnetic thermal therapy, commercial dampers, and polishing etc. In order to comprehend the mechanical behaviors of magnetic fluid, researchers developed several theoretical models for different flow conditions. However, due to the extensive calculation, theoretical models are only applicable for some special problems, such as 2-dimensional and axial symmetry. In recent years, with the development of computer performance, simulation has become an important method to investigate the MR mechanism of magnetic fluid. This paper reviews the recent progress in the theory and simulation of magnetic fluid. Firstly, theoretical models of magnetic fluid under shear mode, squeeze mode, and valve mode are introduced. Secondly, the existing simulation methods for magnetic fluid, such as molecular dynamics, particle-level dynamic simulation, and finite element method, are illustrated. The validity of the methods and their merits and drawbacks are discussed. Then, the research progress of the simulation of magnetic fluid is summarized from 3 aspects: Simulations of mechanical properties of novel magnetic fluid, simulations of complex mechanical behaviors of conventional magnetic fluid, and simulations of biomagnetic fluid. Finally, some future trends of simulation of magnetic fluid are proposed. The following 3 topics should be emphasized in the future work. First, a comprehensive theoretical model considering a variety of microscopic interactions is required. In order to prepare magnetic particles with high MR effect, excellent dispersibility, and low density, surface coating, modification, and additive agents are usually applied in experiments. Unfortunately, the influence of non-magnetic components on the MR effect is seldom considered in simulations. Second, current simulations could not simultaneously obtain the macroscopic mechanical properties and microstructures of magnetic fluid in complex flow. Finite element method and computational fluid dynamics are applicable for complex macroscopic problems but can not obtain the microstructures at the same time. Mesoscopic simulation methods can not exhibit large-scale aggregations of particles, which leads to the deviation compared with experiments. To establish multi-scale simulation methods and improve the accuracy of simulations have become an urgent requirement. Combining simulation methods with different spatial scales and reducing the time cost by using machine learning have become a possible approach. Third, multi-physics coupling simulation methods should be established. The magnetic field controlled electrical properties of magnetic fluid have attracted researchers interest in recent years. Magnetic fluid with this novel controllable property could be widely applied in battery and sensors. Investigations on other physical properties of magnetic fluid by using mechanical, electrical, and magnetic model together will be a future trend. These achievements will all contribute to the development of high-performance magnetic fluids and further enlarge the range of applications of magnetic fluid.

Because of the potential applications in the optical fields, the ultra-precision cutting of titanium alloys is attracting the interest of many researchers. Aimed at the problem of tool wear and poor surface quality in the ultra-precision cutting of titanium alloys, the method of ultrasonic vibration was used to assist the ultra-precision turning of titanium alloy for improving the machinability and better surface integrity. A lot of experiments of ultrasonic-assisted ultra-precision turning (UAUT) have been done to investigate the cutting phenomenon in UAUT of Ti6Al4V alloy. In addition, the effect of cutting parameters (amplitude of vibration, spindle speed, depth of cut and feeding speed) on the surface roughness, surface morphology, chip morphology and cutting force has been analyzed deeply. The results showed that the amplitude of ultrasonic vibration played the most important role in UAUT of Ti6Al4V alloy.

In this paper, a new method based on phase congruency is proposed to measure pitch lengths and surface braiding angles of two-dimensional biaxial braided composite preforms. Lab space transform and BM3D (block-matching and 3D filter) are used first to preprocess the original acquired images. A corner detection algorithm based on phase congruency is then proposed to detect the corners of the preprocessed images. Pitch lengths and surface braiding angles are finally measured based on the detected corner maps. Experimental results show that our method achieves the automatic measurement of pitch lengths and the surface braiding angles of biaxial braided composite preforms with high accuracy.

Polyacrylonitrile (PAN) is an attractive precursor for N-doped porous carbons owing to its high nitrogen content and good thermal stability. Herein, a facile and effective route for the synthesis of N/S co-doped porous carbon by capitalizing on hetero-atom containing PAN as a doped carbon source and ZnCl2 as a volatile porogen is reported. Notably, the optimal porous carbon (denoted as FeZ-CNS-900) with a large specific surface area of up to 1730 m2 g−1 exhibits excellent oxygen reduction reaction (ORR) activity with a half-wave potential of 0.881 V, which is 39 mV more positive than that of commercial Pt/C under alkaline conditions, as well as robust durability and methanol tolerance. Interestingly, the use of N/S co-doped porous carbon also offers comparable ORR activity yet much higher stability than that of Pt/C under acidic conditions. Finally, the implementation of FeZ-CNS-900 as the air-cathode catalyst for primary Zn–air batteries yields an open-circuit potential of 1.49 V, a high peak power density of 168 mW cm−2, a large specific capacity of 778 mA h gZn−1 (corresponding to an energy density of 1020 W h kgZn−1) and a remarkable durability.

In this study, the normal stress in magnetorheological polymer gel (MRPG) under large amplitude oscillatory shear was investigated using experiments and particle-level simulations. Under large amplitude oscillatory shear, an intensely oscillating normal stress was measured with a period of exactly half the strain period. As the amplitude of the strain increased, the peak of the normal stress increased and the trough decreased. Changes in the normal stress were mainly caused by two factors: the Poynting effect, in which shear produces a normal force perpendicular to the shear direction, and magnetic-induced normal stress, which changes with the particle structure. In MRPG, both effects are related to the particle structure. The particle structure in MRPG with different strain was calculated and the simulation results show that the amplitude of the structural strain in oscillatory shearing is less than that of the applied strain. Additionally, a phase difference was observed between the structural strain and the applied strain. Based on the calculated particle structure, the change in the normal stress was obtained and found to agree well with the experimental results.

Due to the characteristics of high strength, high chemical activity and low heat conduction, titanium alloy materials are generally difficult to machine. As a typical titanium alloy with higher strength and lower heat conductivity, the machinability of titanium alloy TC21 is very poor and its cutting process is companied with larger cutting force and rapid tool wear. Straight-tooth milling tool is often used to cut the groove and side surface in the titanium alloy parts. And the milling method can be used to investigate the cutting mechanism because the cutting force has only two components and the better chip morphology is obtained. To investigate the straight-tooth milling process of TC21 alloy, a series of milling force experiments have been done. In addition, a 3D finite element model (FEM) for the straight-tooth milling process of TC21 alloy is presented to simulate the milling process. In the model, the constitutive material model, the failure model, the friction model and the heat transfer model were adopted. Through the simulation, chip formation, stress distribution, cutting force and milling temperature were obtained. The cutting force reaches its maximum when the spindle speed reaches about 13000 rpm, and then decreases as the speed continues to increase. The results confirmed that the similar “Salomon” phenomenon existed in the cutting process of TC21 alloy.

This work reports porous carbonyl iron particles/multiwalled carbon nanotubes-polydimethylsiloxane composites (PCMCs) with high flexibility and low density. In comparison to the solid product, the porous PCMC possesses a larger elongation and deformation. Because of the excellent magnetic-mechanic-electric coupling performance, the flexible composite exhibits bimode sensitivity to both the external stresses and magnetic field. Typically, the normalized resistance variation (Δ R/ R) of PCMC reaches 82.8% and 52.2% when the compression strain and tension strain are 60% and 50%, respectively. Moreover, the Δ R/ R induced by bending, twisting, and magnetostress also changes remarkably. When a 144 mT magnetic field is applied, the Δ R/ R of PCMC increases with 3.6%. To further understand the magnetic-mechanic-electric coupling mechanism, a conductive network sensing model is proposed and analyzed. Finally, on the basis of the bimode PCMC sensor array, a smart chessboard which can precisely discriminate special chesses with different masses and magnets is developed. This study provides a new fabrication method for next-generation three-dimensional smart sensors toward artificial electronics and soft robotics.

This work studied a flexible and stretchable magnetoactive elastomer (MAE) film consisting of carbonyl iron (CI) particles and polydimethylsiloxane (PDMS) elastomer matrix. The deformation of the MAE film was investigated using digital image correlation (DIC) and laser Doppler velocimetry (LDV) methods. The MAE film with free boundary is highly wrinkled under a magnetic field generated by an electromagnet with the current of 0.65 A. While in fixed boundary condition, the maximum deformation appears at the center point, and the maximum displacement reaches 0.63 mm when the current is 3 A. The finite element method (FEM) results demonstrate that the maximum internal stress and strain are 33 kPa and 2.3%, respectively. The FEM results are in good agreement with the DIC and LDV tests. With the exceptional magnetic controllability, the MAE film can find extensive applications in intelligent control systems, acoustic absorption devices, and haptics.

This work reported a simulation study on the optimal diameter (D) and wall thickness (H) of hollow Fe3O4 microspheres to improve the magnetorheological (MR) effect. Modified formulae for the magnetic dipolar force, van der Waals force, and hydrodynamic drag force were employed in the simulation model. Typical evolution of shear stress and microstructures in steady shear flow was obtained. The shear stress-strain curve was divided into linear, fluctuant, and homeostasis regions, which were related to the inclination of particle chains and the lateral aggregation. For hollow Fe3O4 microspheres with different diameters and wall thicknesses, the shear stress curves collapsed onto a quadratic master curve. The best wall thickness was H = 0.39D for a 20 wt% MR fluid and H = 0.35D for a 40 wt% MR fluid, while the optimal diameter was D = 1000 nm and D = 100 nm, respectively. The maximum shear stress of the 40 wt% MR fluid was twice that of the 20 wt% MR fluid. The change of shear stress was due to the competition that results among the magnetic interaction, number of neighbors, tightness, and orientation of the particle chains. Simulated dimensionless viscosity data as a function of Mason number for various diameters, wall thicknesses, and weight fractions collapsed onto a single master curve. The simulated shear stress under both a magnetic field and shear rate sweep matched well with experiments.

This work studied the rheological properties and magnetorheological (MR) mechanism of dry magnetorheological fluid (MRF) under various working modes. A novel simulation method combining the discrete element method and computational fluid dynamics was developed, in which the bilateral coupling between particles and the flow field of the matrix (air) was considered. The microstructures and mechanical properties in the redispersion process, shear mode, and valve mode were systematically simulated for the first time. The results indicated that dry MRF presented superior redispersion property and response time (several μs) than liquid-based MRFs. In shear mode, the magnetic dipolar force and friction force dominated the evolution of microstructures. In valve mode, the magnetic dipolar force and viscous drag force of air became the main interactions. Magnetic particles aggregated into sturdy chain structures and hindered the airflow. The MR effect in valve mode was the pressure gradient of the matrix, which increased up to 1.08 × 105 Pa m−1 with the increasing particle volume fractions and decreased under a large inflow velocity. The best MR effect in valve mode was achieved under a magnetic field of B = 63 mT. Simulations revealed the influence of dimensionless Mn and Re number on the MR effect. The pressure gradient of the matrix was controlled by the external field and can be utilized to design a dry MRF valve for precious and transient vibration control. Simulated dimensionless shear stress in shear mode agreed well with experiments. This work will promote the development and applications of novel high-performance MRFs.

Transparent conductive films (TCFs) have received much research attention in the area of aeronautical canopies. However, bad wear, corrosion resistance and weak erosion performance of TCFs dramatically limit their scalable application in the next-generation aeronautical and optoelectronic devices. To address these drawbacks, three types of optically transparent coatings, including acrylic, silicone and polyurethane (PU) coatings were developed and comparatively investigated ex situ in terms of Taber abrasion, nanoindentation and sand erosion tests to improve the wear-resistance and sand erosion abilities of ITO-coated PMMA substrates. To elucidate the sand erosion failure of the coatings, the nanoindentation technique was employed for quantitative assessment of the shape recovery abilities under probe indentation. Results show that the PU topcoats can greatly enhance the sand erosion properties, which were superior to those of acrylic and silicone topcoats. This result can be attributed to the good toughness and self-healing properties of PU topcoats. Additionally, high hardness and good Taber abrasion properties of the ITO films and silicone topcoats did not have an obvious or affirmatory effect on the sand erosion abilities, based on their brittleness and irreparable properties under sand erosion.

A mechanically activated solid-state displacement reaction has been investigated as a means of manufacturing apatite nanoparticles. Mechanical milling and subsequent heat treatment of a CaCl 2 , Na 3 PO 4 and NaCl reactant mixture resulted in the formation of chlorapatite nanoparticles embedded within a solid salt matrix. The size and morphology of the chlorapatite nanoparticles was found to depend on the temperature of the post-milling heat treatment. A low temperature of 400 °C yielded largely equiaxed nanoparticles with an average diameter less than 100 nm. In contrast, heat treatment at 775 °C resulted in the formation of chlorapatite nanorods with an average diameter below 200 nm and a [001] growth direction. In both cases, removal of the salt matrix by washing with water gave powders with low levels of agglomeration.

Surface braiding angle and pitch length are two important parameters for characterizing and evaluating the performance of three-dimensional braided composite preforms. In this paper a new method based on an improved curvature scale space corner detector with adaptive threshold is proposed for measuring these parameters, with applications to three-dimensional, four-directional carbon-fiber braided composite preforms. First, the original image is acquired using a system employing ‘dome light source + CCD camera + circular polarizing filter’. Second, the original image is processed using Lab transform and BM3D (block-matching and 3D filter). Third, the corners are detected using an improved curvature scale space corner detector with adaptive threshold. Finally, the pitch lengths and surface braiding angles are measured from the detected corners. Experimental results show that the proposed method can achieve automatic measurement of the pitch length and surface braiding angle with smaller average errors relative to manual measurements compared with alternative schemes.

In this work, a superparamagnetic fluid based on Fe 3 O 4 hollow nanospheres was developed and the influence of the particle structure on the rheological properties was investigated. The Fe 3 O 4 hollow nanospheres which were prepared by using the hydrothermal method presented the superparamagnetic characteristic, and the magnetic fluid thereof showed well magnetorheological (MR) effect. The stable magnetic fluid had a high yield stress even at low shear rate and its maximal yield stress was dramatically influenced by the measurement gap. In comparison to the Fe 3 O 4 nanoparticles based magnetic fluid (MF), the Fe 3 O 4 hollow nanospheres based MF exhibited better MR effect and higher stability since the unique hollow nanostructure. The shear stress of the hollow nanospheres is about 1.85 times larger than the nanoparticles based MF because it formed stronger chains structure under applying a magnetic field. To further investigate the enhancing mechanism, a molecule dynamic simulation was conducted to analyze the shear stress and the structure evolution of the Fe 3 O 4 hollow nanospheres based MF and the simulation matched well with the experimental results.

Electro-analytical (E-chem) biosensors offer unique advantages over widely used optical biosensors and can be considered ideal for low-cost, mass-deployable point-of-care (PoC) diagnostic devices [1]. They possess fully electronic and real-time transduction methods and require little or no external instrumentation. Despite these advantages, two fundamental challenges have hampered broad adoption of E-chem biosensors: 1C design and transducer (surface) material suitability. E-chem sensors require both low-noise and high detection dynamic range (DDR) front-end circuits and must also accommodate electrode-electrolyte interfaces with significant PVT variations and temporal drifts [2]–[5]. The absence of CMOS-compatible bio-electronic interfaces with adequate chemical and thermal stability has been another impediment [6].

The influence of the particle size on the rheological property of magnetic fluid was studied both by the experimental and computer simulation methods. Firstly, the magnetic fluids were prepared by dispersing Fe3O4 nanospheres with size varied from 40 nm to 100 nm and 200 nm in the solution. Then, the rheological properties were investigated and it was found that the relative magnetorheological effects increased with increasing the particle size. Finally, the molecular dynamic simulation was used to analyze the mechanical characteristics of the magnetic fluid and the chain-like model agreed well with the experimental result. The authentic chain-like structure observed by a microscope agreed with the simulation results. The three particles composed of the similar cluster nanostructure, thus they exhibited similar magnetic property. To this end, the unique assembling microstructures was the origination of the mechanical difference. And it was found that the higher MR (magnetorheological) effects of the large particle based magnetic fluid was originated from the stronger assembling microstructure under the applying magnetic field.

Uniform Co 3 O 4 @MoO 2 nanosheet arrays is fabricated through hydrothermal and electrodeposition method by virtue of the chemical-etching method. The electrochemical measurements show that the specific capacitance of 600 F g −1 at a scan rate of 2 mV s −1 for the Co 3 O 4 @MoO 2 hybrid is higher than both pristine MoO 2 and Co 3 O 4 . Moreover, the hybrid electrode with low resistance displays good cyclic stability of 83% retention after 1000-cycle charge/discharge. These results indicate that the as-prepared Co 3 O 4 @MoO 2 hybrid is a potential candidate used as electrode material in supercapacitors.

NiO with different morphologies were fabricated via hydrothermal method in different kinds of solvent. The morphology of the obtained NiO samples varied from nanoflakes to nanoparticles with the different volume ratios of water to ethanol. The electrochemical results showed that the specific capacitance of NiO-S5 obtained in ethanol was up to 1337.5 F g −1 at a current density of 0.62 A g −1 , which was greatly higher than that of the other samples. These results indicated that NiO-S5 had the superior electrochemical behavior which may be due to its small-size effect.

This work studied the effect of interparticle friction force on the magnetorheological properties for magnetic fluid using particle-level dynamic simulations. A novel numerical model considering the friction force and elastic normal force between coarse microspheres was developed. The analysis revealed the relationship between magnetic fluid microstructure and friction coefficient (μ) of particles for the first time. Under steady shear flow, plate-like aggregations were formed under a moderate friction coefficient (μ≈ 0.2), while thick chains with large inclinations were observed under strong friction forces (μ > 1.5). When 0.2 ≤ μ ≤ 1.5, the friction forces hardly affected the rheological properties. If μ > 1.5, friction forces could enhance the shear stress by 102%. Friction force hampered the relative movement of magnetic particles in the thick chains and enlarged the average dip angle of microstructures. The magnetic dipolar force between microspheres generated stronger shear stress in such particle aggregations. The optimal friction coefficient was determined as 2 ≤ μ ≤ 2.75 in simulations by considering the saturation magnetizations, external fields, shear rates, and particle concentrations. The enhancement of shear stress was relevant to the relative strength between magnetic force and friction interaction. Simulated shear stress in magnetic field sweep matched well with experiments in the literature. This work will open a promising avenue in the development of high-performance magnetic fluid.

This work reported a carbon layer modified magnetite (Fe3O4) nanospheres (Fe3O4@C) which could be applied in preparing high performance magnetic fluid. The porous Fe3O4@C nanospheres were prepared by calcinating the Fe3O4@Polydopamine (Fe3O4@PDA) precursor in N2 atmosphere. The shear stress of Fe3O4@C-based magnetic fluid was as high as 24.9 Pa at saturated magnetic field, which was about 3.8 times larger than pristine Fe3O4-based magnetic fluid (6.6 Pa). Furthermore, the particle level dynamic simulation was employed to analyze the microstructure evolution and shear stress of Fe3O4@C-based magnetic fluid under applying an external magnetic field. The chain-like model well explained the magnetorheological (MR) mechanism and the simulation results matched perfectly with the experimental data. Since the crystallinity of Fe3O4 was improved during the pyrolysis, Fe3O4@C nanospheres possessed a higher saturation magnetization. The stronger magnetic dipolar forces and chain-chain interactions resulted in a much steadier Fe3O4@C chain-like structure. As a result, it was found that the superior MR performance and high stability of the Fe3O4@C-based magnetic fluid were originated from the core-shell and porous structures of Fe3O4@C. This work proposed a valuable magnetic particle model to prepare high performance magnetic fluid and further understand the origination of MR effects.

The degradation of lithium-ion batteries resulted from electrolyte decomposition may be indicated by the change in diffusion coefficient, De, and concentration, Ce. Although De and Ce are included in the liquid-phase diffusion process of a pseudo two-dimensional (P2D) model, these two important parameters are always inundated or contaminated when the complete P2D model is reduced. To obtain De and Ce reliably, a new parameter-lumped model of concentration overpotential, based on the reduced liquid-phase diffusion partial differential equation (PDE)in P2D model by Pade approximation, is developed with two main contributions. First, as the basis of Pade-based approximation, new analytic solutions of liquid-phase diffusion PDE are derived under the improved boundary conditions with the mass conservation principle. Second, in the proposed parameter-lumped model, the target parameters of De and Ce are grouped with other unknown but fixed parameters, respectively, which guarantees that even if the specific values of target parameters cannot be obtained, their changing trajectories can also be independently and effectively observed by lumped parameters. Finally, the simulation accuracies of reduced dynamic electrolyte concentration expressions are compared with that from other simplified methods, and the identification accuracy of the lumped parameters is verified under different working conditions.

Tunable and reversible dry adhesion has important applications in transfer printing, precision manufacturing, and intelligent robotics. In this paper, a novel composite pad is fabricated whose adhesion can be adjusted rapidly and reversibly by the magnetic field. The composite pad consists of a cylindrical polydimethylsiloxane (PDMS) shell and a magnetorheological polymer gel (MRPG) core. The mechanical properties of the MRPG core in the pads are sensitive to the magnetic field. So the adhesion of the composite pad can be changed due to the interface stress modulation by the magnetic field. The interface stress is calculated by using the finite element method to study the mechanism of magnetically controllable adhesion. The results show the smaller the edge stress, the larger the adhesion. So composite pads with four different core shapes are prepared to optimize the structure design. Pad-bump has the largest magnetically tunable adhesion interval. The adhesion of composite pads on uneven surfaces is also tested and the results show the adhesion of composite pads with soft cores is improved compared to the solid core pad. Finally, a magnetic field controlled pick-and-place demonstration experiment shows that the composite pad array has great application potential in magnetically controlled grabbing and release.

The filter cake in polycrystalline enterprise has high water content and therefore a large volume, which is difficult to regenerate, the common treatment method is to stack and landfill in the waste dumps. With the environmental pressure has became serious these years, it has a great significance to reduce the volume of filter cake. This research studied the filtration performance of different filtration methods for the polycrystalline enterprise waste water, namely traditional Chamber Filter Press, Chamber Filter Press & passing compressed air, Diaphragm Filter Press. The results showed that the water content of filter cake pressed by traditional Chamber Filter Press is 80.6%, the passing compressed air method decreases the water content slightly. However, the water filter pressed method reduced the water content and the volume of the filter cake remarkably. It is more in accord with the national development production strategy of environmentally friendly, safety and efficiently.

NiS/CoS/NiCo2S4 microflower with hierarchical structure is successfully prepared via facile hydrothermal method. The supercapacitive performance displays that the specific capacitance is up to 513 F g−1 at a scan rate of 1 mV s−1. The obvious redox peaks on the cyclic voltammetry curves reveal pseudocapacitive performance of NiS/CoS/NiCo2S4. Furthermore, the glucose detection behavior of NiS/CoS/NiCo2S4 modified electrode (NiS/CoS/NiCo2S4/GCE) has also been performed. Amperometric study indicates that this non-enzymatic sensor displays excellent electrocatalytic performance to glucose. The glucose diffusion from the solution to the electrode surface is the kinetic control process. These results indicate a potential application of NiS/CoS/NiCo2S4 for using as an electrode material in supercapacitors and glucose sensor.

A flexible self-powered magnetism/pressure dual-mode sensor, which consists of magnetorheological plastomer (MRP), was developed in this work. The working mechanism of the self-powered sensor was based on the displacement reaction of Fe and CuSO4. Different from traditional flexible pressure sensors, it was not only sensitive to a slight pressure (1.3 kPa), but also responsive to a small magnetic field (12 mT). Under an external magnetic field, the micro-scale carbonyl iron (CI) particles in the MRP electrode aggregated into the chain-like and the cluster-like structures, which enhanced the electrochemical activity of ions in the electrolyte of the electrode materials and formed the conductive network. The voltage increased with the magnetic field strength and the sensitivity was 4.2% at a 252 mT magnetic field. To further explore the mechanism of sensor, the microstructure evolution of CI particles inside the electrode materials under different magnetic fields was simulated by particle-level dynamics method. Finally, a smart writing board based on a self-powered magnetism/pressure dual-mode sensor array was developed and it was sensitive to different magnetic fields without an external power supply, which demonstrated a broad potential for mobile electronic device in the non-contact state.

Biochar derived from waste biomass has proven as a promising sorbent for removal of heavy metals from wastewater. However, proper disposal of such a heavy metal-containing biochar is challengeable. The major objective of this study is to create a reuse way by converting the heavy metal-loaded biochar into supercapacitor. Two biochars were produced from dairy manure and sewage sludge, respectively, and subjected to sorption of Ni from solution, and then the Ni-loaded biochar underwent microwave treatments for fabrication of supercapacitor. The specific capacitance of biochar supercapacitor increased with Ni loading, especially the Ni-loaded biochar further treated with microwave in which the capacitance increased by over 2 times, compared to the original biochar supercapacitors. The increase of capacitance in the Ni-loaded biochar supercapacitor following microwave treatment was mainly attributed to the conversion of Ni into NiO and NiOOH, which was evidenced by X-ray diffraction and X-ray photoelectron spectroscopy. The biochar supercapacitors, especially microwave-treated Ni-loaded biochar supercapacitors exhibited the high stability of specific capacitance, with less than 2% loss after 1000 charge-discharge cycles. This study demonstrated that Ni-loaded biochar can be further utilized for generation of supercapacitor, providing a potential way for the reuse of exhausted carbonaceous sorbents.

A nonlinear magnetic droplet in a flow-focusing channel is studied in this letter. The breakup regime of the droplets undergoes a transition from dripping to bifurcation to dripping. A GMR (giant magnetoresistance) sensor is proposed for droplet detection. When this nonlinear droplet passes, the sensor can produce a continuous jitter signal which is significantly different from the one obtained in the dripping mode. The MR (magnetoresistive) ratio is about 3.2%. The droplet magnetic field obtained by molecular dynamics simulation demonstrates that the GMR sensor is effective in the detection.A nonlinear magnetic droplet in a flow-focusing channel is studied in this letter. The breakup regime of the droplets undergoes a transition from dripping to bifurcation to dripping. A GMR (giant magnetoresistance) sensor is proposed for droplet detection. When this nonlinear droplet passes, the sensor can produce a continuous jitter signal which is significantly different from the one obtained in the dripping mode. The MR (magnetoresistive) ratio is about 3.2%. The droplet magnetic field obtained by molecular dynamics simulation demonstrates that the GMR sensor is effective in the detection.

In this article, a method based on gray projection is proposed for automatic measurement of surface braiding angle and pitch length of braided composite preforms. The surface braiding angles are measured by rotated gray projection. First, the original image is preprocessed using Lab transform and block-matching and three-dimensional filter. Then, edge map of gray scale is acquired based on phase congruency and non-maximum suppression. Third, edge direction angles are computed by image rotation and gray projection. Finally, the average surface braiding angles are measured from the edge direction angles. The pitch lengths are measured by cropped gray projection. First, the original image is filtered by an artistic edge and corner enhancing filter. Second, block images are cropped based on gray projection. Finally, pitch lengths are measured by block images gray projection. Experimental results show that the proposed method can achieve the automatic measurement of average surface braiding angle and average pitch length of two-dimensional braided composite preform with high accuracy.

Yttrium fluoride films were grown on silicon wafers by magnetron sputtering at different substrate temperatures (ST). The composition, structure and optical properties have been investigated systematically. X-ray photoelectron spectroscopy (XPS) analysis shows that the films mainly contain Y and F elements. The deficiency of F element in yttrium fluoride films is generally inevitable by magnetron sputtering. Glancing incident X-ray diffraction (GIXRD) analysis demonstrates that the films have the orthorhombic structure with different growth orientations. Spectroscopic Ellipsometer (SE) analysis on films exhibits that the refractive index of yttrium fluoride film grown at 400 °C posses lower value than these of ones under other temperatures. The absorption of films gradually diminishes as the substrate temperature increases. It has been convinced that the YF 3 films with optimal optical properties can be achieved by adjustment of substrate temperature for desirable optical design and applications.

Berries are rich resources of secondary metabolites, particularly known for diverse phenolic compounds. These highly bioactive compounds can be developed into novel nutraceutical and pharmaceutical products, as well as high-added-value natural food additives. Compounds extracted from berries have, e.g., been used as colorants (e.g., anthocyanins) [1]. Meanwhile, some phenolics present in berries are of high added value due to their potential to develop into anticancer drugs (e.g., phenolic acids, flavonols, and flavanols) [2]. The antioxidation properties from berries also make them attractive research subject to develop more efficient nutraceutical products than the current crude extraction formulas (e.g., NutriPhy® Bilberry 100 from Chr. Hansen) [3, 4]. To exploit the full potential of the phenolic molecules from berries, a number of research projects have been conducted ranging from identification of bioactive compounds and elucidation of metabolic pathways (metabolic engineering them into suitable industrial production host cells) to eventually commercial production [3, 5–12].

In this paper, we have studied the hot forming process of composites made by polylactic acid (PLA) and corn straw fiber. In order to obtain the composite cushioning material with ideal density and expansion ratio, the parameters of processing was optimized. It showed that the optimum condition as follows: the hot-press time was 5min, the pressure was 15MPa and the temperature was 200°C. The structure of the composite was characterized by FTIR.

Although polydimethylsiloxane (PDMS) transfer during microcontact printing (microCP) has been observed in previous reports, which generally focused on only one or a few different substrates, in this work we investigate the extent of PDMS transfer onto a series of surfaces with a wide range of hydrophobicities using an uninked, unpatterned PDMS stamp. These surfaces include clean silicon, clean titanium, clean gold, "dirty" silicon, polystyrene, Teflon, surfaces modified with PEG, amino, dodecyl, and hexadecyl monolayers, and also two loose molecular materials. The PDMS transferred onto planar surfaces is, in general, easily detected by wetting and spectroscopic ellipsometry. More importantly, it is detected by time-of-flight secondary ion mass spectrometry (ToF-SIMS) because of the sensitivity of this technique to PDMS. The effect of surface free energy on PDMS transfer in microcontact printing is investigated, and the relationship between the amount of PDMS in ToF-SIMS spectra and the surface tensions of initial surfaces is revealed. We show that PDMS transfer can be applied as a probe of surface free energies using ToF-SIMS, where PDMS preferentially transfers onto more hydrophilic surface features during stamping, with little being transferred onto very hydrophobic surface features. Multivariate curve resolution (MCR) analysis of the ToF-SIMS image data further confirms and clarifies these results. Our data lend themselves to the hypothesis that it is the free energy of the surface that plays a major role in determining the degree of PDMS transfer during microCP.

Here we show direct polymer growth on hydrogen-terminated silicon (Si-H) as a one-step process. Si-H is immersed in a heated solution of an initiator, a monomer, and a crosslinker. The resulting polymer films are 2-15 nm thick, the thickness can be tuned by varying reaction conditions, and the polymer films are robust. Thinner films are obtained in polymer growth without crosslinker. Radicals produced by the initiator and in growing polymer chains may pluck H atoms from Si-H to make reactive dangling bonds. These in turn appear to react with monomers and crosslinkers. Crosslinkers tethered through one double bond may be grafted into polymer chains growing in solution. Surface reactivity is demonstrated by optical ellipsometry, X-ray photoelectron spectroscopy, atomic force microscopy, and wetting.

In this letter, we report a new and extremely rapid technique for surface modification, which we term laser activation modification of semiconductor surfaces or LAMSS. This method consists of wetting a semiconductor surface (e.g., silicon or germanium) with a reactive compound and then firing a highly focused nanosecond pulse of laser light through the transparent liquid onto the surface. The high peak power of the pulse at the surface activates the surface so that it reacts with the liquid with which it is in contact. Evidence for functionalization of the spots is given by ToF-SIMS imaging and small-spot XPS.

The multi-wall carbon nanotubes (MWNTs) were synthesized by chemical vapor deposition (CVD) using LaNi 5 alloy particles as catalyst. The effect of 40–60 nm MWNTs treated with different temperature in nitrogen on the electrochemical properties of CNTs–Ni electrode were investigated. Three-electrode system was introduced for testing electrochemical hydrogen storage of the electrode. The CNTs–Ni electrodes were used as the working electrode, which were prepared by mixing MWNTs and Ni powder in a weight ratio of 1:10 (MWNTs:Ni). Ni(OH) 2 /NiOOH worked as the counter electrode and Hg/HgO as the reference electrode. A 6 mol/L KOH solution acted as the electrolyte. MWNTs treated with different temperature in nitrogen ambient represented a great discrepancy in the electrochemical hydrogen storage capability under the same testing condition. The CNTs–Ni electrodes with 40–60 nm diameter CNTs which were treated in a temperature of 800 °C in nitrogen has the best electrochemical hydrogen storage capacity of 588.1 mAh/g and a corresponding discharging plateau voltage of 1.18 V. From 500 to 800 °C, the higher temperature the MWNTs treated, the better the electrochemical hydrogen storage property of them is. This shows that the temperature of treatment is an important factor that influences electrochemical hydrogen storage performance of MWNTs.