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In this study, the Fe-Cr-Ni-Si and WC alloy coatings were deposited on the polished 2Cr13 steel samples by using a laser cladding technique. The microstructure, tribology and erosion-corrosion resi...

This paper investigates the effect of grain size on the evolution and shear behavior of lead-free solder joints. The grain size of the solder is 2-11 μm, 5-15 μm, 15-25 μm, respectively. The interface structure of the solder joint and the microstructure of the inferred surface are analyzed. The void ratio of the flip-chip solder layer is tested. In order to study the change of shear strength and fracture surface, the solder/copper joint was subjected to isothermal aging treatment (1000 h) under the environment of relative humidity of 85 °C/85%. The results show that the smaller the solder crystal grains, the larger the surface area of the crystal grains per unit mass. Because of the action of the liquid bridge force, tin powder agglomeration is prone to occur, which leads to a high void rate of the solder layer. At this time, a higher activity flux is required to remove oxides. Highly active flux (NC559-TPF) was added and verified. When the grain size is 5-15 μm, the solder paste has the best soldering performance. After the filament is aged for 1000 h, the junction temperature is the lowest. Secondly, the blue light flux is the highest.

The effects of modifiers on the anti-wetting and anti-icing property of the prepared rough aluminum surface were investigated. The rough aluminum substrates were obtained through electrochemical oxidization with 15 wt% sulfuric acid solution as the electrolyte at the constant current of 4 mA for 3 h. And then they were modified with octadecanoic acid (C18), polyethylene (PE), polystyrene (PS), polyethylene glycol (PEG) and hexamethylenetetramine (HMTA), respectively, whose surface free energies were 27.6, 31.0, 33.0, 61.6 and 70.0 mN/m, respectively. The contact angles (CA) were 154.6°, 128.4°, 127.6°, 5.0° and 0.0°, respectively, and the ice adhesion pressures were 15.9, 36.3, 55.9, 155.3 and 216.1 kPa, respectively. The ice adhesion strengths decrease along with the increasing anti-wetting property of aluminum surfaces and the decreasing of the surface energy of modifiers. These provide some new insights when designing the aluminum surface with anti-icing properties in some special applications.

Tandem catalysis, in which a CO2-to-C2 process is divided into a CO2-to-CO/*CO step and a CO/*CO-to-C2 step, is promising for enhancing the C2 product selectivity when using Cu-based electrochemical CO2 reduction catalysts. In this work, a nanoporous hollow Au/CuO–CuO tandem catalyst was used for catalyzing the eCO2RR, which exhibited a C2 product FE of 52.8% at −1.0 V vs. RHE and a C2 product partial current density of 78.77 mA cm−2 at −1.5 V vs. RHE. In addition, the C2 product FE stably remained at over 40% over a wide potential range, from −1.0 V to −1.5 V. This superior performance was attributed to good matching in terms of the optimal working potential and charge-transfer resistance between CO/*CO-production sites (Au/CuO) and CO/*CO-reduction sites (CuO). This site pair matching effect ensured sufficient supplies of CO/*CO and electrons at CuO sites at the working potentials, thus dramatically enhancing the formation rate of C2 products.

Some inevitable disadvantages (being thick and heavy with narrow broadband) restrict the application of Cu-based absorbers in microwave absorption field, which can be overcome by finely modulating the morphology and component of 1D structures. Here, we reported ethylenediamine-steered in situ two-step reduction reactions, which allowed the tunable preparation of CuxNi1−x (x = 0, 0.005, 0.02, 0.0344, 0.0934, 0.1581, 0.2243, and 1) composites with continuously tunable components and morphology varying from smooth rods to urchin-like rods and microspheres. The recombination of Ni with Cu into CuxNi1−x composites can tune crystallite size, inner stress, lattice constant, component, shape as well as properties. The CuxNi1−x (x = 0.0344–0.1581) composites exhibited stronger and wider absorption band under a lower filling mass fraction and thinner sample than other Cu-based absorbers. Due to the combined action of double dielectric relaxation, double magnetic resonances, high attenuation, and good impedance match. The optimal microwave absorption capability (MACs) was achieved for Cu0.0344Ni0.9656 microspheres with a maximum RL value of − 67.5 dB at 14.74 GHz and a broad frequency band (99% attenuation) of 15.41 GHz, corresponding to 1.7–10 mm sample thickness. Owing to tunable saturation magnetization and excellent MACs, the CuxNi1−x composites can work as a kind of promising absorber for applications in electronic equipment and devices.

Sapphire substrates with different crystal orientations are widely used in photoelectric applications. Double-sided planetary grinding is a new process for the rapid thinning and flattening of sapphire, and experiments with it were carried out on sapphire substrates with four commonly used crystal orientations (C-plane (0001), A-plane (11 2 ‾ 0), M-plane (10 1 ‾ 0), and R-plane ( 1 ‾ 012)). By comparing the material removal rates (MRRs), surface topographies, damages, and wear debris among substrates with the four crystal orientations, the removal mechanism for each orientation was revealed. The results showed that the MRR and surface quality of the substrates varied greatly with the four orientations. The R-plane was removed in the form of large pieces of spalled material and had the highest MRR and the largest surface roughness (Sa) of approximately 780 nm among the orientations studied. The C-plane was mainly removed in the form of unique large step-like pieces of spalled material, had the lowest MRR among the orientations observed, and exhibited an Sa of approximately 430 nm. The machinability of the A-plane and M-plane orientations were similar. Both were removed as small pieces of spalled material, and their surface quality was good, with Sa values of 340–390 nm. The experimental results revealed that crystal orientations with lower Young's modulus and fracture toughness values were easier to remove material from, and vice versa. Therefore, to obtain a reasonable material removal rate and a good surface quality of sapphire substrates, different processing techniques are needed for different crystal orientations.

In this paper, the external transverse magnetic field is used to assist the laser-MIG hybrid welding for Ti-6Al-4V (TC4). The microstructure and mechanical properties such as microhardness and tensile properties of the weld joints under 24 mT external magnetic field (EMF) and the referring weld joint without EMF are investigated and discussed. Results show that transfer layer (TL) performs the lowest microhardness in the weld seam and tensile specimens fail in this area for the referring weld joint without EMF, which indicates the TL is the weakest zone in the weld seam. The mechanical properties of weld seam improve significantly under 24 mT EMF, which average microhardness in TL increases 9.3% and failure stress of tensile specimens improve by 16.7%, whilst a mixed fracture mode is operative in the fracture surfaces. The research reveals the elementary microstructure of TC4 laser-MIG hybrid welding is in correlation to welding heat input under the influence of EMF.

Type-III ELMy H-mode plasmas are a valuable operating scenario, as they may simultaneously achieve fusion power gain of Q = 10 and acceptable steady-state and peak power fluxes to the plasma-facing components. It is important to investigate cryogenic deuterium pellet injection fueling in this kind of H-mode plasma since it has been chosen as a main plasma fueling technique for ITER. Recently, pellet fueling experiments have been successfully carried out on EAST, an ITER-like tokamak. A maximum electron density of 0.73 × nGW has been obtained. It is found that ELM behavior was modified immediately and a string of small ELMs were induced when pellets were injected at a low velocity from ˜40 cm above the mid-plane on the low field side, which is different from the fact that pellets trigger signal ELMs in Type-I ELMy H-mode plasmas in other tokamaks. The decreased edge temperature caused by the cryogenic pellet was proposed as the reason for this ELM modification. These results will provide a useful reference for the pellet fueling in a Type-III ELMy H-mode plasma on ITER in the future.

The charging and discharging of molten salt thermal storage is of great importance to the operation and maintenance of the solar power plant. The molten salt bubble column is proposed for solar thermal storage, which is regarded as direct contact heat exchanger. The gas from the solar field is directly injected into the molten salt bubble column. High heat transfer rates can be achieved between the gas and the molten salt due to the direct contact. The hydrodynamics and heat transfer characteristics of the gas molten salt bubble column are numerically analyzed based on the two fluid model, which incorporating the interfacial area transport equation. Simulation results are compared with experimental data from previous literature and our lab. The predictions of lateral profiles of the axial liquid velocity, overall gas holdup and temperature rising rate are in well agreement with the experimental data. Therefore, the models can be used to simulate the behaviors of gas-molten salt bubble column. The effect of superficial gas velocity, static liquid height, operation pressure and inlet gas temperature are discussed. Numeric results show that the volumetric heat transfer coefficient and rising rate of average molten salt temperature increase by increasing superficial gas velocity or operation pressure, and decrease by increasing the static liquid height. The molten salt temperature decreases along the height gradually and the distribution of molten salt temperature in the bubble column is almost uniform during the process.

The charging and discharging of molten salt thermal storage is of great importance to the operation and maintenance of the solar power plant. The molten salt bubble column is proposed for solar thermal storage, which is regarded as direct contact heat exchanger. The gas from the solar field is directly injected into the molten salt bubble column. High heat transfer rates can be achieved between the gas and the molten salt due to the direct contact. Numeric study on the hydrodynamics and heat transfer characteristic of the gas molten salt bubble column is carried out based on the two fluid model. The effect of the superficial gas velocity, gas inlet temperature and static liquid height are discussed. It is found that the volumetric heat transfer coefficient increases by increasing the superficial gas velocity and decreases by increasing the static liquid height. The distribution of the gas volume fraction varies from uniform flow to non-uniform flow and the heat rate become large as the gas superficial velocity increases.

In organic solar cells, photogenerated singlet excitons form charge transfer (CT) complexes, which subsequently split into free charge carriers. Here, we consider the contributions of excess energy and molecular quadrupole moments to the charge separation process. We investigate charge photogeneration in two separate bulk heterojunction systems consisting of the polymer donor PTB7-Th and two non-fullerene acceptors, ITIC and h-ITIC. CT state dissociation in these donor-acceptor systems is monitored by charge density decay dynamics obtained from transient absorption experiments. We study the electric field dependence of charge carrier generation at different excitation energies by time delayed collection field (TDCF) and sensitive steady-state photocurrent measurements. Upon excitation below the optical gap free charge carrier generation becomes less field dependent with increasing photon energy, which challenges the view of charge photogeneration proceeding through energetically lowest CT states. We determine the average distance between electron-hole pairs at the donor-acceptor interface from empirical fits to the TDCF data. The delocalisation of CT states is larger in PTB7-Th:ITIC, the system with larger molecular quadrupole moment, indicating the sizeable effect of the electrostatic potential at the donor-acceptor interface on the dissociation of CT complexes., 11 pages, 6 figures

Lower cost and smaller volume are imperious demands for active optical measuring and imaging systems. Different from the traditional methods using separate light emitting devices and light detecting devices, a novel way is provided to acquire a simple active optical detecting system. It is found that a commercial light emitting diode (LED) can work as a photodetector utilizing the fact that localized photogenerated carriers within an appropriate p–n junction escape efficiently. Furthermore, a prototype of a simple active optical detecting system is fabricated with a commercial LED wafer on which a light emitting device and a light detecting device are integrated monolithically. It is measured out a good ability in detection for a target with a smooth or rough surface. These results exhibit a considerable possibility of a cheap, flexible and small simple active optical detecting system.

The polyethyleneimine dithiocarbamate was employed as polymers to synthesize Fe3Pt-Ag nanocomposites by using the seed deposition method. Fe3Pt-Ag nanocomposites were utilized for the catalytic degradation of methyl orange(MO) in the presence of NaBH4. Fe3Pt-Ag nanocomposites showed good chemical catalytic activity and stability in pollutants degradation. Furthermore, Fe3Pt-Ag nanocomposites can keep their efficiency till four cycles. The results suggest that the nanocatalysts with recyclability have broad prospects in environmental conservation applications.

As a method for plasma density control, Edge Localized Mode (ELM) mitigation and refueling, a Supersonic Molecular Beam Injection (SMBI) system is successfully developed and implemented for the Experimental Advanced Superconducting Tokamak (EAST). The SMBI is designed to produce a 400–1200 m/s molecular beam of hydrogen/deuterium for injecting into the plasma. An innovative system for measuring the injected particle number is also developed to increase the measuring accuracy of SMBI. In addition, a movable structure of the nozzle is designed to adjust the distance between the nozzle and plasma, in order to improve the fueling efficiency of SMBI by decreasing this separation distance. The successful implementation of SMBI provides an important tool for studying plasma density feedback control and ELM mitigation on the EAST campaign. To the best of our knowledge, the engineering design process of the SMBI system on the EAST has not been reported previously; therefore, the structure, implementation details, and the test results of the SMBI system are presented herein for the first time.

The objective of this study was to develop a multi-steps infrared macro-fingerprint method to discriminate Dendrobium huoshanense “Fengdou” (DHS FD) produced under different toasting and soaking conditions as well as to examine the effect of production conditions on the total polyphenol content, total water soluble polysaccharide content, and antioxidant activities. The results showed that though the Fourier transform infrared and second derivative infrared (SD-IR) spectra of the DHS FD processed under different conditions were similar visually, the DHS FDs could be discriminated by their characteristic peaks in the range of 1800–600 cm–1 from their IR and SD-IR files and the cross-peaks in the region of 1280–950 cm–1 in their two-dimensional correlation spectroscopy IR spectra. The total polyphenol content increased and the total water soluble polysaccharide content decreased in the DHS FDs toasted at temperatures from 110°C to 190°C for 30 min. Soaking process showed variable effects on the total polyphenol content and total water soluble polysaccharide content. The total polyphenol content of the DHS FDs toasted below 150°C increased as the soaking temperatures increased while the total water soluble polysaccharide content showed an opposite trend. Both the total polyphenol content and total water soluble polysaccharide content of the DHS FDs toasted at 170°C and 190°C showed little difference when soaking temperatures varied from 4°C to 100°C. The investigation of the 2,2-Diphenyl-1-picrylhydrazyl cleaving activity revealed that toasting and soaking process might increase the antioxidant activity of the DHS while too high toasting temperatures would decrease their activity. The multi-steps infrared macro-fingerprint analysis with high resolution and excellent macroscopic fingerprint features could effectively discriminate the DHS produced under different conditions without involving any separation and extraction. Consequently, the use of this method is recommended for quality control of the DHS FD.

In order to reduce energy consumption of the solution evaporation concentrating process with high boiling point elevation (BPE), a novel cogeneration system is proposed to integrate the solution evaporation concentrating and power generation processes using the exhaust waste heat as heat source. Through compared with the conventional three-effect and mechanical vapor recompression evaporation processes, influences from the key operation parameters, including the evaporation temperature and BPE of the solution on overall thermal performance of the proposed system have been investigated. The results showed the overall thermal performance of the three schemes became worse with the rise of the BPE, but the proposed cogeneration system showed prominent thermal performance when dealing solutions with high BPE compared to those of the conventional three-effect and MVR evaporating processes. Moreover, through harmonizing the vacuum evaporation concentrating process and net power output, the optimal evaporating temperatures to achieve the maximal energy saving potential are obtained under different BPE working conditions for the proposed cogeneration system.

The photo-generated currents of GaAs solar cells with different lengths of space charge region are obtained and analyzed in this study. The enhanced absorption coefficient in the space charge region is adopted to calculate the photo-generated current based on the solar cell physics theory. The calculated currents coincide well with the experimental currents both under single wavelength incidence and solar spectrum irradiation conditions.

The synthesis of ultrathin metal nanosheets (NSs) attracts broad scientific and technological interest, and it still remains a challenge for non-noble metals like nickel due to their intrinsic cubic symmetry and high surface energy. Herein, we report a NiO intermediated solvothermal method towards the synthesis of ultrathin Ni NSs (thickness < 3 nm) using N,N-dimethylformamide as the solvent and n-butylamine as the shape controlling reagent. The growth of the ultrathin Ni NSs follows an intermediate mechanism which was proved by the results obtained by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray absorption spectra (XAS) and X-ray photoelectron spectroscopy (XPS). Under solvothermal conditions, the nickel acetylacetonate precursor was first reduced to a NiO NS intermediate, then reduction occurred and NiO NSs were reduced to Ni NSs. The synthesized ultrathin Ni NSs predominately in a metallic state showed high selectivity (88.0-92.0%) towards styrene (ST) in the phenylacetylene (PA) semihydrogenation reaction under mild conditions (323 K, 1 atm of hydrogen) in a broad PA conversion range (2.0-98.0%). The low coverage of oxygen atoms on the Ni NS surface is proposed to account for the high ST selectivity, as indicated by density functional theory (DFT) calculations.

This paper presents a new type of circulation system combining heat pump and liquid gap membrane distillation (LGMD) for the concentration of sulfuric acid solution. The proposed hybrid system not only has a simpler flow configuration, but it also demonstrates significant thermal performance advantages. Based on the principle of conservation of mass and energy, a mathematical model is established in Aspen Plus to simulate working conditions. Through varying the relevant parameters, the solution with low boiling point elevation to achieve the maximum water production gain to output ratio (GOR) value was obtained, which is approximately 33 times that of the conventional system under the given condition in this research. Given the temperature difference between the condenser and the evaporator in the heat pump cycle, the higher membrane flux and the maximal value of GOR are obtained at the high feed temperature. However, increasing the molar fraction of the feed solution sharply decreases both the membrane flux and GOR, especially at high feed solution temperatures. Additionally, it was found that the high GOR are obtained when selecting the high boiling point working fluids. Therefore, these results can provide significant references for the further implementation and optimization of the proposed system.

The optical absorption is the most important macroscopic process to characterize the microscopic optical transition in the semiconductor materials. Recently, great enhancement has been observed in the absorption of the active region within a p–n junction. In this paper, GaAs based p–i–n samples with the active region varied from 100 nm to 3 μm were fabricated and it was observed that the external quantum efficiencies are higher than the typical results, indicating a new mechanism beyond the established theories. We proposed a theoretical model about the abnormal optical absorption process in the active region within a strong electric field, which might provide new theories for the design of the solar cells, photodetectors, and other photoelectric devices.

The absorption coefficient is usually considered as a constant for certain materials at the given wavelength. However, recent experiments demonstrated that the absorption coefficient could be enhanced a lot by the PN junction. The absorption coefficient varies with the thickness of the intrinsic layer in a PIN structure. Here, we interpret the anomalous absorption coefficient from the competition between recombination and drift for non-equilibrium carriers. Based on the Fokker–Planck theory, a non-equilibrium statistical model that describes the relationship between absorption coefficient and material thickness has been proposed. It could predict the experimental data well. Our results can give new ideas to design photoelectric devices.

The paper presents high frequency pellet injectors developed for edge localized mode mitigation and plasma fuelling of the EAST and KSTAR tokamaks. Each pellet injector is able to inject solid deuterium or hydrogen pellets at steady state mode. Injectors consist of modules including screw extruder cooled by liquid helium and pneumatic punchers for pellet fabrication and acceleration which are optimized to reach maximal injection frequency for specified pellet parameters. The EAST pellet injector is capable of injecting 1.5 mm diameter and 1.2–1.8 mm length pellets at frequency up to 50 Hz with velocities 200–250 m/s using two injection modules working in an alternating mode at 25 Hz each. Injection reliability over 90% has been confirmed during several cycles of continuous D2 pellet injection at 50 Hz. The KSTAR pellet injector has been designed to inject 2 mm size pellets at frequency up to 20 Hz and velocity 200 m/s. Due to improved design of pellet fabrication and acceleration system the world record in continuous injection of 20,164 deuterium pellets (O2.0 × 1.5 mm) for 1039 s at 20 Hz with reliability 97% has been achieved.

Numerical studies of buckling failure and debond propagation were carried out on composite sandwich columns with face/core debond. Nonlinear simulations with cohesive elements were carried out by Abaqus 6.14 to predict the buckling modes and debond propagation in sandwich composite columns. For specimens with embedded circular face/core debond, the debond propagated in the interface along the direction which was perpendicular to the compression direction until the through-the-width debond was formed. After that, the face/core debond propagated along the compression direction just as these specimens with through -the-width rectangle debond. Comparisons of the experimental and simulated ultimate loads associated with failure modes showed a good agreement. The maximum error of ultimate load was 10.61%, which proved that the model was capable of predicting accurate buckling loads and post-buckling behaviors.

An organic Na-ion battery is reported with a polyanionic 9,10-anthraquinone-2,6-disulfonate (Na2 AQ26DS, 130 mAh g-1 ) cathode and the Na-intercalated state (Na4 TP) of sodium terephthalate (Na2 TP, 255 mAh g-1 ) as the anode. The resulting full cells deliver the maximum discharge capacity of 131 mAh g-1 cathode in 0.5-3.2 V, simultaneously maintaining the average value of ≈62 mAh g-1 cathode during 1200 cycles (0.5 A g-1 , ≈4 C). These results are among the best performing organic sodium-ion full cells reported to date.

Vibration-assisted grinding improves machining quality and efficiency over conventional grinding, whereas its atomistic mechanism remains unclear. In this study, we investigated vibration-assisted machining using molecular dynamics simulations of the nano-scratching process by considering single-crystal silicon as the paradigm material. Vibration dynamically redistributes and rebalances the existing anisotropy among the applied forces, thereby leading to unique scratch characteristics including homogeneous deformation. Vibration reduces the tangential and normal force components and effectively suppresses the anisotropic stress state, resulting in a reduction of the amorphous-layer thickness and enlargement of the scratched surface area. The magnitudes of the tangential and normal components vary cyclically with a frequency that is twice that of the applied vibration. Furthermore, when the frequency increases, the tangential and normal components and amorphous-layer thickness decrease gradually, opposite to the scratched surface area. In addition, as the vibration amplitude increases, the tangential and normal components decrease, in contrast with the behaviour of the amorphous layer, which thins gradually and then slightly increased to a constant thickness. Vibration-assisted scratch effectively turns the brittle material at the working spot into a ductile material. Thus, our atomistic insights suggest a new route for optimization of vibration-assisted grinding processes.

This paper investigates the effect of solders with different grain sizes (5–15 μm, 2–15 μm, 2–11 μm) on the mechanical and thermal reliability of flip-chip LED chip Au/Sn Ag Cu/Cu solder joints during reflow soldering. The lead-free solder SAC305 was selected as the solder. The microstructure of the IMC interface and the inferred surface of the solder joint is observed, and the microstructure evolution of the solder joint is analyzed. The void ratio of the solder joints under different grain sizes is tested to characterize the influence of the contact area between the chip and the solder joints on the shear stress. In addition, the solder joints were aged for 1000 h under a relative humidity of 85 °C/85%. The photoelectric thermal performance of the FC-LED filament and the influence of high temperature and high humidity aging on the reliability of the filament were tested and analyzed. The results show that when the size of the solder paste is small and the uniformity is poor within a certain range of solder size, the voids in the flux layer are large and concentrated, and the void ratio is significantly higher, which leads to a decrease in the mechanical reliability of the solder joints. The thermal resistance test results show that the cavity will cause excessive thermal resistance, poor heat dissipation, a significant increase in junction temperature, and a decrease in thermal reliability, which in turn leads to severe light aging and ultimately changes in photoelectric performance. When the grain size is 5–15 μm, the uniformity of the particle size is good. After the filament is aged for 1000 h at high temperature and humidity, the light maintenance rate remains at 65.6%, and the filament performance is stable and reliable. It has certain reference value in the actual production process.

To investigate the special electrical phenomena in a graphene/ferroelectric field-effect transistor, we perform density-functional first-principles calculations on a graphene/LiNbO3 (0001) hybrid structure, and then study the effects of a Au counter electrode and water adsorption. Graphene is p-type and n-type doped by a LiNbO3 positive and negative surface, respectively, and the conductivity increases while the Dirac cone persists. The Au counter electrode introduces an additional charge injection relative to the surface polarity and weakens the electrostatic doping effect. With the help of the electrons from the Au counter electrode, water adsorption could switch the conductive type of graphene. We also find an interesting phenomenon whereby the coupling of graphene with a negative surface is significantly stronger than that with a positive surface, possibly related to the different polar terminals (LiO3/Nb).

A 50 Hz pellet injection system, which is designed for edge-localized mode (ELM) control, has been successfully developed and integrated for the Experimental Advanced Superconducting Tokamak (EAST). Pellet injection is achieved by two separated injection system modules that can be operated independently from 1 to 25 Hz. The nominal injection velocity is 250 m/s with a scatter of ±50 m/s at a repetition rate of 50 Hz. A buffer tank and a two-stage differential pumping system of the pellet injection system was designed to increase hydrogen/deuterium ice quality and eliminate the influence of propellant gas on plasma operation, respectively. The pressure of the buffer tank could be pumped to 1 × 10 2 Pa, and the pressure in the second differential chamber could reach 1 × 10 −4 Pa during the experiment. Engineering experiments, which consisted of 50 Hz pellet injection and guiding tube mock-up experiments, were also systematically carried out in a laboratory environment and demonstrated that the pellet injection system can reliably inject pellets at a repetitive frequency of 50 Hz.

It is of great significance to select appropriate welding process parameters for obtaining optimal weld geometry in hybrid laser-arc welding. An integrated optimization approach by combining Kriging model and GA is proposed to optimize process parameters. A four-factor, five-level experiment using Taguchi L 25 is conducted considering laser power (P), welding current (A), distance between laser and arc (D) and traveling speed (V). Kriging model is adopted to approximate the relationship between process parameters and weld geometry, namely depth of penetration (DP), bead width (BW) and bead reinforcement (BR). The constructed Kriging model was used for parameters optimization by GA to maximize DP, minimize BW and ensure BR at a desired value. The effects of process parameters on weld geometry are analyzed. Microstructure and micro-hardness are also discussed. Verification experiments demonstrate that the obtained optimum values are in good agreement with experimental results.

Controllable doping of iron (Fe) (3.9–17.8%) in hollow porous silica spheres with highly homogeneous distribution state was achieved successfully by a one-pot hydrothermal synthesis strategy. Based on the observation and analysis by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, nitrogen sorption, and X-ray photoelectron spectroscopy (XPS), it was found that molecular Fe species were intercalated into silica framework during the structural transformation of silica to hollow flake-shelled spheres, which leads to both stable fixation with open accessibility of Fe and high surface area of the Fe-doped silica hollow spheres (Fe-SHSs). When used as heterogeneous Fenton catalyst to degrade the dye of Acid orange 7 (AO7), enhanced catalysis performance was exhibited due to the sufficiently exposed active sites and fast mass transport in the system. The optimal catalysis condition was also studied by adjusting Fe-SHSs dosages, oxidant concentrations, and pH values). This work presents an effective strategy for chemical doping of metal components in the silica structures and may also be explored for other supported metal catalyst systems.

The self-driving of water droplets on textured substrate is momentous for understanding the directional transport of water on biological surface. In this paper, a novel design of monolayer graphene-covered wedge-shaped copper substrate (GWCS) is put forward to realize the directional and ultrafast spontaneous driving of water droplets from the tip of the wedge-shaped substrate to the wide end. The self-driving behaviors of water droplets on GWCS are studied by classical molecular dynamics. The results show that the maximum spontaneous driving velocity of water droplet driven by surface wetting gradient and Young-Laplace pressure gradient can reach 73.8 m/s. The law of energy variation during the whole droplet self-driving on GWCS indicates that there is a competitive relationship between the potential energy of water droplet and the interaction energy between the droplet and GWCS, i.e. the interaction energy between water droplet and GWCS is partially converted into the potential energy of water droplet. The relationship of the maximum displacement of water droplet with the wedge angle, wettability of GWCS and the droplet surface tension is proposed in theory, and the influence of the discontinuous linear increase of the wedge-shaped substrate width on a nanoscale on the self-driving is analyzed and used to explain the little difference between the theoretical and simulation results. Furthermore, a smaller droplet is easier to obtain larger spontaneous driving velocity, and the influence of long-distance decelerating motion of high-speed small droplet on the non-wetting gradient substrate on the droplet displacement law is clarified. Finally, the mechanism of graphene suspended on both sides of the wedge-shaped copper structure to enhance the droplet transport efficiency is determined. The results will have theoretical significance in designing the functional texture surface covered by monolayer graphene to realize droplet self-driving.

Lysine is an essential amino acid for human body, and lysine sulfates are at risk of fire and explosion during the production and processing. However, there is no public report on the lysine sulfate powder explosion hazard research. In this paper, the effects of moisture, mass concentration and particle size on the flame propagation behaviors of L-lysine sulfate powder were studied in a vertical pipe. The results showed that the flame propagation could be divided into 3 stages: free propagation, acceleration and attenuation, in which the acceleration was owed to the positive feedback of combustion reaction, gas expansion and turbulence. Moisture content could promote the flame propagation of L-lysine sulfate powder to a certain extent, but it had a strong inhibitory effect on the explosion when the moisture content was too large. The flame propagation velocity increased with the decrease of the average particle size of powder,.With the increase of the particle concentration, the flame propagation velocity of powder explosion increased first and then decreased, that was, there was an optimal concentration of powder explosion, and the powder was more sensitive to the change of concentration in the range of low concentration.

A high frequency deuterium pellet injection system based on extrusion and pneumatic acceleration has been recently developed and built for EAST tokamak, which is one of fully superconducting Tokamaks with ITER-like plasma configuration. It is mainly used for plasma edge localized mode control and can achieve 1–50 Hz injection rate. It has been completely installed on EAST up to now. A new differential pumping system and pellet transmission lines have been designed according to the actual condition of EAST. Recently we have tested the system systematically and injected multiple pellets into type-I ELMy H-mode plasma on EAST for the first time. The test and experimental results show that the system can inject continuous pellets into plasma stably, and ELMs can be triggered by deuterium pellets in H-mode plasma with negligible impact on density and stored energy. And it was also found that ELM trigger efficiency is less than 100 % sometimes. This lays an important foundation for further experimental study of ELM modulation using deuterium pellet injection on EAST.

We present a method to extend the operating wavelength of the interband transition quantum well photodetector from an extended short-wavelength infrared region to a middle-wavelength infrared region. In the modified InAsSb quantum well, GaSb is replaced with AlSb/AlGaSb, the valence band of the barrier material is lowered, the first restricted energy level is higher than the valence band of the barrier material, the energy band structure forms type-II structure. The photocurrent spectrum manifest that the fabricated photodetector exhibits a response range from 1.9 μm to 3.2 μm with two peaks at 2.18 μm and 3.03 μm at 78K.

Microfluidic systems have been regarded as a potential platform for high-throughput screening technology in drug discovery due to their low sample consumption, high integration, and easy operation. The handling of small-volume liquid is an essential operation in microfluidic systems, especially in investigating large-scale combination conditions. Here, we develop a nanoliter centrifugal liquid dispenser (NanoCLD) coupled with superhydrophobic microwell array chips for high-throughput cell-based assays in the nanoliter scale. The NanoCLD consists of a plastic stock block with an array of drilled through holes, a reagent microwell array chip (reagent chip), and an alignment bottom assembled together in a fixture. A simple centrifugation at 800 rpm can dispense ~160 nL reagents into microwells in 5 min. The dispensed reagents are then delivered to cells by sandwiching the reagent chip upside down with another microwell array chip (cell chip) on which cells are cultured. A gradient of doxorubicin is then dispensed to the cell chip using the NanoCLD for validating the feasibility of performing drug tests on our microchip platform. This novel nanoliter-volume liquid dispensing method is simple, easy to operate, and especially suitable for repeatedly dispensing many different reagents simultaneously to microwells.

The microscale organic Rankine cycle (ORC) system is considered a promising technology to recover thermal energy from widely distributed low-temperature heat sources. By using HFC-R225fa as...

A new high frequency pellet injector has been developed for edge localized mode mitigation and plasma fuelling of the EAST tokamak. The pellet injector consists of two independent modules operating at 1–25 Hz. Both modules are equipped with screw extruders cooled by liquid helium for solid deuterium ice production at steady state mode. An innovative pellet fabrication and acceleration system has been designed and applied to reduce gas load on the extruders in 4–5 times and to increase the pellet injection reliability. Pellets of 1.5 mm diameter and 1.5 mm length were injected at 250 ± 50 m/s velocity at 25 Hz with reliability over 93% using one module in preliminary tests. Two modules working in turn are under tests now. It is anticipated they will be able to inject pellets at 50 Hz after further technical improvements in near future.

The welded joints of dissimilar materials have been widely used in automotive, ship and space industries. The joint quality is often evaluated by weld seam geometry, microstructures and mechanical properties. To obtain the desired weld seam geometry and improve the quality of welded joints, this paper proposes a process modeling and parameter optimization method to obtain the weld seam with minimum width and desired depth of penetration for laser butt welding of dissimilar materials. During the process, Taguchi experiments are conducted on the laser welding of the low carbon steel (Q235) and stainless steel (SUS301L-HT). The experimental results are used to develop the radial basis function neural network model, and the process parameters are optimized by genetic algorithm. The proposed method is validated by a confirmation experiment. Simultaneously, the microstructures and mechanical properties of the weld seam generated from optimal process parameters are further studied by optical microscopy and tensile strength test. Compared with the unoptimized weld seam, the welding defects are eliminated in the optimized weld seam and the mechanical properties are improved. The results show that the proposed method is effective and reliable for improving the quality of welded joints in practical production.

Single phase Bi 4 LaTi 3 FeO 15 ceramics with a four-layered Aurivillius structure were synthesized by successfully inserting LaFeO 3 into Bi 4 Ti 3 O 12 matrix, and their structural, multiferroic and dielectric properties were investigated. Typical ferroelectric behavior with remnant polarization (2 P r ) of about 12 μC/cm 2 , large dielectric constant, small dielectric loss and a weak ferromagnetic behavior are obtained simultaneously at room temperature. As a result, possible magnetoelectric coupling effect is obtained near the ferromagnetic Curie temperature. Meanwhile, the weak ferromagnetism can be enhanced at lower temperature, and thus a larger saturation magnetization of about 1.2 emu/g is obtained at 5 K. In addition, two sets of dielectric relaxation are observed and discussed based on defect relaxation theory.

Metal-oxide TFT (MOTFT) is promising for next generation high information content displays for both portable and TV/monitor applications. With current manufacturing capacity established originally for a-Si TFT, it would be ideal to develop a MOTFT structure and process most compatible with the equipment available on existing a-Si TFT line with minimal upgrade and corresponding capital investment. With such intention, we have developed bottom-gate, top-source/drain MOTFT with photopatternable organic etch-stopper (ES) with performance meeting product specifications. Backplane with such MOTFT can be made with same mask counts as that with BCE process.