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A novel composite basing on the Fe3O4 nanoparticle, the graphite oxide nanosheet (GON), and the citric acid-crosslinked β-cyclodextrin polymer (CA-CDP) was prepared for the purpose of removing the methylene blue (MB) dye from water. The structure of the resultant Fe3O4/GON/CA-CDP composite was investigated by the scanning electron microscope, the two dimensional EDS mapping, the thermal gravimetric analyzer, the Fourier transform infrared spectroscope, the wide angle X-ray diffraction, the X-ray photoelectron spectroscope, and the zeta potential measurement. The Fe3O4/GON/CA-CDP composite not only had a good MB adsorption capacity of 173 mg/g but also a high saturation magnetization of 36.4 emu/g. It was found that the MB adsorption capacity of the Fe3O4/GON/CA-CDP composite increased with the increasing initial MB solution pH value especially in the low-pH-value range. Moreover, the MB adsorption mechanism, the MB adsorption isotherm, and the MB adsorption kinetic of the Fe3O4/GON/CA-CDP composite were investigated. It was found that 1) the good adsorption ability of the Fe3O4/GON/CA-CDP composite for the MB dye originated from the electrostatic attraction, the Lewis acid-Lewis base interaction, the host-guest supramolecular interaction and the π-π interaction, and 2) the MB adsorption isotherm and the MB adsorption kinetic of the Fe3O4/GON/CA-CDP composite could be well explained by the Sips model and the intraparticle diffusion model, correspondingly.

Surface treatment is quite vital to reduce the reverse leakage current and improve the current On–Off ratio of gallium nitride (GaN) quasi-vertical Schottky barrier diode (SBD). In this work, we report a new nondestructive low temperature supercritical CO2 fluid (SCF) nitridation technology to treat the surface of GaN and substantially reduce the leakage current of GaN quasi-vertical SBD. The X-ray photoelectron spectroscopy (XPS) reveals the increased nitriding degree and oxygen doping degree in the form of GaO x after the SCF process results in the leakage performance improvement. As a result, the defects at metal/semiconductor interface are passivated. Also, because of NH-2 and OH− generated from the SCF process, the surface peak electric field of n−GaN decreases, and thus the breakdown voltage is enhanced. The reverse leakage current density is reduced by more than three orders of magnitude from $3.7\times 10^{-{6}}$ to $3.52\times 10^{-{9}}$ A/cm2 (at −3 V) and the ON-/ OFF-current ratio is improved by three orders from $8\times 10^{{7}}$ to $5.74\times 10^{{10}}$ .

The tetrafluoroterephthalonitrile cross-linked β-cyclodextrin was first subjected to the carboxylation reaction, followed by the deposition of the Fe3O4 nanoparticles on its surface to obtain the n...

To high-precision control the springback of high-strength steel (HSS) in cold roll forming, the 3D finite element analysis (FEA) models of hat-shaped sectional HSS roll forming process were built with the professional roll forming software COPRA. Two conventional angle adjusting methods for HSS, i.e., the Namaste-type and the Platform-type applied widely for complex-sectional normal steel, easily lead to the edge waves and asymmetric behavior, respectively, especially high springback that is difficult to control by the FEA simulation and practical production of HSS cold roll forming process. The roll design of the UDT (USTB-Durable T)-type angle adjusting method was developed to significantly reduce springback with the improvement of the edge waves and asymmetric behavior in the hat-shaped sectional HSS roll forming process by the FEA simulation. The proposed angle compensation method based on UDT-type angle adjusting method achieved high-precision springback control by the FEA simulation, which provides a novel approach for springback control effectively in complex-sectional HSS roll forming process. The industrial application gives remarkable results that the hat-shaped sectional HSS product can strictly meet market requirements of less than 0.5° by the proposed angle compensation method based on UDT-type angle adjusting method.

In this paper, a magnetic graphene oxide (MGO) composite was prepared by the click reaction between the alkyne-modified Fe3O4 nanoparticles and the azide-modified graphene oxide for the purpose of removing the Congo red (CR) dye from water. The deposition of the Fe3O4 nanoparticles on the graphene oxide to successfully prepare the MGO composite was evidenced by the Fourier-transform infrared spectrometer, wide-angle X-ray diffraction equipment, scanning electron microscope, thermal gravimetric analyzer, and Raman spectrometer. The value of saturation magnetization for the MGO composite was 34.9 emu/g. The CR absorption capacities of the MGO composite increased first and then decreased as the pH value increased. It was found that the maximum adsorption capacity of the MGO composite for the CR was as high as 769.2 mg/g. In the absorption-desorption experiment, the CR absorption capacities of the MGO composite from the second cycle to the fifth cycle remained stable to be about 130 mg/g. Moreover, both the Langmuir model for the adsorption isotherm and the pseudo-second-order kinetic model could be used to describe the CR absorption behaviors of the MGO composite.

The energy conversion efficiency of the electromagnetic ultrasonic transducer (EMAT) is extremely low. To solve this problem, this paper applied linear frequency modulation (LFM) pulse compression technology to electromagnetic ultrasonic thickness measurement to improve the signal-to-noise ratio. The EMAT excited by chirp signal was simulated by finite element analysis, and the echo signal obtained by the simulation was subjected to pulse compression. After adding noise, the result showed that the EMAT signal-to-noise ratio was increased more than 6dB compared with the echo signal excited by Toneburst signal. In addition, this paper also applied spectrum modification method to suppress the sidelobes of the output signal, further improving the signal-to-noise ratio by 1.6dB.

In order to meet the requirements of flexible HVDC transmission project and improve the current density of single IGBT chip, the design and optimization of 4500V edge termination structure were carried out. A VLD edge termination structure and a multi-step field plate plus field-limiting ring (MFPFLR) edge termination structure were designed by TCAD simulation software. The influence of Si/SiO2 interface charge on the edge termination structure was simulated and studied. And the breakdown voltage characteristic curve and potential distribution of the two edge termination structures were compared. Finally, the MFPFLR edge termination has better characteristics, and was verified on a 4500V IGBT chip. The test results show that the 4500V IGBT chip with two different edge termination structures meet the design expectation, and the key parameters of 4500V IGBT chip with MFPFLR edge termination structure were significantly optimized compared with VLD edge termination structure.

Development of a new complex technology such as 3D NAND requires significant efforts in terms of materials screening, process tuning, and device design leading to fabrication and characterization of many test wafers with significant time-to-market cost. In this context, modeling can help accelerate 3D NAND technology development. Therefore, in this work, modeling platform is used to investigate such devices. Cross-talk (or cell-to-cell interference) is one of the major concerns in NAND technology, preventing its further scaling. To reduce crosstalk between neighboring cells in this paper, we analyze a 3D NAND structure with separated charge trap regions and compare its performance with the conventional device having continuous charge trap region.

It is a promising cooling strategy to use the heat pipe for the Li-ion battery module, which can maintain the temperature of the battery module properly and prevent high temperature, triggering the...

The saturated vapor oxidation behavior of GH2984 alloys at 750 °C were investigated by oxidation weight increasing method, X-ray diffraction and scanning electronic microscopy in different dissolved oxygen concentrations. The results show that the oxide film of GH2984 alloys in different dissolved oxygen concentrations is of a single layer consisting of continuous Cr2O3. The oxidation mass gain of GH2984 alloys slightly increases with the increase of the dissolved oxygen concentrations in water vapor. Oxygenated treatment could accelerate the internal oxidation phenomenon, enhance the oxidation film thickness and make the scattered nodular bulges of Fe2O3 disappear and more Cr-rich nodular bulges form. Moreover, high dissolved oxygen concentrations do not affect the stabilization of Cr2O3 but contribute to the formation of a little Al2O3 and TiO2 which are oxidized internally.

AlCu5MnCdVA alloys had high specific strength, good machining and fatigue properties, outstanding electroplating and excellent corrosion resistance. However, due to wide crystallization temperature range, it is hard to realize sequential solidification for AlCu5MnCdVA alloy by traditional casting process. Laser Powder Bed Fusion (L-PBF) has become one of the most promising technology in Metal Additive Manufacturing (MAM). In this study, L-PBF was employed to fabricate AlCu5MnCdVA parts, and both mesoscopic numerical element model and experimental printing were applied to study the feasibility of L-PBF Additive Manufacturing AlCu5MnCdVA alloy. Relative densities, phase analysis and micromorphology were investigated systematically by SEM, EDS and XRD. The laser process parameters window for AlCu5MnCdVA were obtained: volumetric energy density 41–51 J mm−3, laser power 230–240W, laser scanning speed 1200–1325 mm s−1. And the relative density of parts fabricated by L-PBF reached 96.1%. Besides, AlCu5MnCdVA alloy fabricated by L-PBF was mainly consist of α-Al, little other phase such as Al2Cu or Al2Mn3 was detected.

Compositing graphene oxide (GrO) as a robust support into MIL-53(Cr) can provide a feasible strategy to stabilize its flexible structure from CO2-triggered shrinkage, resulting in an enhanced CO2 uptake together with a higher CO2/CH4 adsorptive selectivity of the GrO@MIL-53(Cr) composites for biomethane upgrade. In this work, a series of novel GrO@MIL-53(Cr) composites were prepared from GrO and MIL-53(Cr). Their adsorptive performance for CO2/CH4 separation was experimentally investigated. IAST was applied to predict their adsorptive selectivity for CO2/CH4 separation. Results show that a small amount of GrO doping (1%) could significantly improve surface area and pore volume of the resulting 1GrO@MIL-53(Cr), while a remarkably enhanced CO2 uptake was observed with sufficient GrO doping (10%) for 10GrO@MIL-53(Cr) at 5 bar and room temperature, which is 62% higher than that of its parental MIL-53(Cr). XRD indicates a quenched “breathing effect” could be responsible for the remarkably enhanced CO2 uptake. With this quenched breathing effect, 10GrO@MIL-53(Cr) shows a 16 times higher CO2/CH4 selectivity at 5 bar for the equimolar CO2/CH4 mixture. SEM and TEM show well-defined compositing structures, while IR, Raman and TG suggest GrO@MIL-53(Cr) composites manage to preserve most of the crystallographic and chemical characteristics of their parent MIL-53(Cr).

In this study, micropatterns on polypropylene films were fabricated via plasma pretreatment and UV-initiated graft polymerization. Firstly, radio-frequency plasma, which does not significantly influence bulk attributes of substrates due to limited penetration depth, was utilized to activate polypropylene films. Then, different sizes of micropatterns of poly(hydroxyethyl methacrylate) (PHEMA) were fabricated on the polypropylene films via UV-initiated graft polymerization of hydroxyethyl methacrylate by using photo-masks. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle (CA) were employed to characterize changes of pristine polypropylene films and modified ones in surface morphology, roughness, hydrophilicity, free energy and the surface chemical composition. All of these confirmed the successful grafting of different sizes of PHEMA micropatterns on the polypropylene surface. Furthermore, the influence of PHEMA micropatterns on cell proliferation and cytotoxicity was evaluated in vitro. Analysis of cell behaviour indicated that PHEMA micropatterns of the appropriate size can promote cellular adhesion and proliferation, and the PHEMA-micropatterned polypropylene films had good biocompatibility. The approach presented here provides an alternative to synthesize on the surface of polypropylene films’ micropatterns with the aim of using them in a diverse array of applications.

A 3300V/62.5A low loss FS-IGBT was developed by using the carrier storage layer structure and laser annealing process on the back p+ collector, which could lower the saturation voltage. The effects of laser annealing energy and P+ collector dose on dynamic and static state were studied. Considering the trade-off of the turn-off loss and the saturation voltage, the IGBT was finally designed with the 2.35V saturation voltage, 132mJ turn-off loss.

Polymer materials with high biocompatibility and versatile functions are urgently required in the biomedical field. The hydrophobic surface and inert traits of polymer materials usually encounter severe biofouling and bacterial infection which hinder the potential application of polymers as biomedical materials. Although many antifouling or antimicrobial coatings have been developed for modification of biomedical devices/implants, few can simultaneously fulfill the requirements for antimicrobial and antifouling activities. Herein, we constructed bifunctional micropatterns with antifouling and antimicrobial properties onto polypropylene (PP) films using argon plasma activation treatment, photomask technique and UV-initiated graft polymerization method. Different sizes of PMPC/PTM/PEGDA micropatterns were fabricated on PP films to yield patterned PP–PMPC/PTM/PEGDA as evidenced by infrared (IR) spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), where PMPC is poly(2-methacryloyloxyethyl phosphorylcholine) for enhancement of hydrophilicity and biocompatibility, PTM is poly(methacryloyloxyethyltrimethylammonium chloride) for contribution to antimicrobial activity and PEGDA is poly(ethylene glycol diacrylate) as the crosslinker. The surface hydrophilicity of patterned PP–PMPC/PTM/PEGDA was characterized by the static water contact angle test. The results showed that the PP sample with a micropattern with the size of 5 μm exhibited the best hydrophilicity. For biological assays of patterned PP–PMPC/PTM/PEGDA, the micropattern size at 5 μm performed the best for both antiplatelet adhesion and antimicrobial activities. We anticipate that this work could provide a new method for building bifunctional biomedical materials to promote the application of PP in biomedical fields.

The electrostatic powder spraying machine with excellent performance can effectively promote the application of electrostatic powder spraying production, which has the characteristics of low pollution, energy saving, economy and high film performance. In order to reasonably optimize structural parameters and ensure the reliability of the movable base of an electrostatic powder spraying machine, multi-objective optimization design and reliability analysis were carried out. Firstly, a parametric geometric model and numerical simulation model for the movable base were established according to the working principle and production conditions of the electrostatic powder spraying machine. Secondly, the static and dynamic characteristics of the movable base were analyzed using ANSYS Workbench software, and the distributions of stress, deformation and natural frequency were obtained. Thirdly, the mathematical model for optimum design of the movable base was established. Taking the thickness of the upper support plate, the spacing between the upper and lower support plates, the width of the angle steel edge and the thickness of the angle steel edge as design variables, and taking the mass, natural frequency and maximum deformation as objective parameters, the response surface method were used to analyze the sensitivity of design variables and to optimize the sizes of the movable base. Finally, taking the optimized sizes with high sensitivity as random input variables, the reliability analysis of the structure was carried out by using Monte Carlo method based on Latin hypercube sampling. The results show that the optimal design results satisfying reliability are effective and reliable.

Enhancing coal permeability with formation heat treatment (FHT) is a prospective method in coalbed methane (CBM) exploitation. Here, the mechanisms of coal permeability enhancement induce by heat treatment are investigated. Residual water coal samples were heated in a helium atmosphere at 50 °C, 100 °C, 200 °C, 400 °C, 600 °C, and 800 °C in sequence. The samples’ permeability and acoustic wave velocity were measured after each heat treatment, and Young’s modulus and shear modulus were calculated to determine the change in the mechanical properties. In addition, changes in the pore structure and surface properties were analyzed with low-pressure N2 adsorption and SEM. The results indicate that in the range of 50–200 °C, the bulk water and interlayer water were removed, which alleviated the aqueous phase trapping effect, enhanced gas flow channels and increased permeability by 4–14 times. Between 400 and 600 °C, the coal samples started to pyrolysis, weakening the mechanical properties of the coal, and fractures were initiated and extended, which caused permeability to increase by 79–1400 times. After 800 °C, the surface of the coal was completely pyrolyzed, samples were cracked, and the permeability increased by more than 20,000 times. Stimulation mechanisms of FHT in CBM reservoirs consist of aqueous phase trapping alleviation, coal fractures caused by mechanical properties weakening and combustion, and finally, the C–C bond and C–O bond of molecules are broken, which induced coal fracture to produce more gas flow channels. For field application of FHT, both advantages and disadvantages are analyzed.

In this paper, the permeability of coal after oxidation treatment and heat treatment was measured. Combined with industrial analysis, infrared spectrum and other experimental means, the mechanism of heat treatment and oxidation treatment on improvement of mass transport ability in coals was analyzed comprehensively. After 240 h oxidation treatment, the average permeability enhancement multiple of coal treated by 15 wt% H2O2 was 5.79, and the average permeability enhancement multiple of coal treated by 0.2 wt% ClO2 was 3.75. A large number of micro fractures and dissolution pores were generated in coal during the oxidation process, which significantly improved the connectivity of pores. The increase of the associated hydroxyl and carboxyl groups weakening the hydrophilicity which were beneficial to the production of coalbed methane. Under the condition of 200 °C heat treatment, the average permeability enhancement multiple of coal was 36.45. After heat treatment, coal composition changed significantly, only water loss occurred when the temperature was lower than the threshold temperature, and organic matter pyrolysis escaped when the temperature was higher than the threshold temperature. Furthermore, the synergistic mechanism of heat treatment and oxidation treatment was discussed. The heat - oxidation treatment enhanced the water phase self-imbibition capacity of the coal, make a large number of oxidants enter into the matrix quickly, and reduce the coal fracture toughness, which was conducive to improving the effect of the oxidation treatment. For the oxidation – heat treatment, the threshold temperature and mechanical strength of the oxidized coal were reduced by the coal structure recombination.

In order to meet the requirements of output torque, efficiency and compact shape of micro-spindles for small parts machining, a two-stage axial micro air turbine spindle with an axial inlet and outlet is proposed. Based on the k-ω turbulence model of SST, the flow field and operation characteristics of the two-stage axial micro air turbine spindle were studied using computational fluid dynamics (CFD) combined with an experimental study. We obtained the air turbine spindle under different working conditions of the loss and torque characteristics. When the inlet pressure was 300 KPa, the output speed of the two-stage turbine was 100,000 rpm, 9% higher than that of a single-stage turbine output torque. The total torque reached 6.39 N·mm, and the maximum efficiency of the turbine and the spindle were 42.2% and 32.3%, respectively. Through the research on the innovative structure of the two-stage axial micro air turbine spindle, the overall performance of the principle prototype has been significantly improved and the problems of insufficient output torque and low working efficiency in high-speed micro-machining can be solved practically, which laid a solid foundation for improving the machining efficiency of small parts and reducing the size of micro machine tool.

Supercritical CO2 fluid is reported as an effective media in optimizing the SiO2/SiC interface in 4H-SiC(0001) MOS structures at a temperature as low as 150 °C. After SCCO2 treatment, the breakdown electric field is improved to 10.7 MV cm−1. The near-interfacial oxide traps is decreased from 1.62 × 1011 to 1.84 × 1010 cm−2. The interface state density at 0.2 eV below E C is reduced from 6 × 1012 to 2.5 × 1012 eV−1 cm−2. A dynamic reaction model is proposed to explain the defect passivation reaction. This technique can be effectively applied to interface semiconductor devices to enhance performance.

Selective Laser Melting (SLM) has become one of the most promising technologies in Metal Additive Manufacturing (MAM), which is a complex dynamic non-equilibrium process involving heat transfer, melting, phase transition, vaporization and mass transfer. The characteristics of the molten pool (structure, temperature flow and velocity flow) have a decisive influence on the final forming quality of SLM. In this study, both numerical simulation and experiments were employed to study molten pool structure, temperature flow and velocity field in Selective Laser Melting AlCu5MnCdVA alloy. The results showed the structure of molten pool showed different forms (deep-concave structure, double-concave structure, plane structure, protruding structure and ideal planar structure), and the size of the molten pool was approximately 132 μm × 107 μm × 50 μm: in the early stage, molten pool was in a state of deep-concave shape with a depth of 15 μm due to multiple driving forces, while a protruding shape with a height of 10 μm duo to tension gradient in the later stages of forming. The metal flow inside the molten pool was mainly driven by laser impact force, metal liquid gravity, surface tension and recoil pressure. For AlCu5MnCdVA alloy, metal liquid solidification speed was extremely fast (3.5 × 10−4 S), the heating rate and cooling rate reached 6.5 × 107 K S−1 and 1.6 × 106 K S−1, respectively. Choosing surface roughness as a visual standard, low-laser energy AlCu5MnCdVA alloy optimum process parameters window was obtained by numerical simulation: laser power 250 W, hatching space 0.11 mm, layer thickness 0.03 mm, laser scanning velocity 1.5 m s−1. In addition, compared with experimental printing and numerical simulation, the width of the molten pool was about 205 um and about 210 um, respectively, and overlapping between two adjacent molten tracks was all about 65 um. The results showed that the numerical simulation results were basically consistent with the experimental print results, which proved the correctness of the numerical simulation model.

Electromagnetic ultrasonic thickness measurement has the advantages of no couplant and no contact. But the signals are so weak that they are easily submerged in the noise. So, the pulse compression technology is applied to raise the signal to noise ratio and lift-off distance effectively. The barker sequences are set as transmitting pulse in the measurement system, the received signals are processed with pulse compression in the experiments. By comparing the performances of barker code with single pulse requiring high levels average filtering, the signal to noise ratio is highly improved. The 5 × 13 combined barker sequence performs best among the different combined barker sequences. Its signal to noise ratio reaches 20.11 dB and the maximum lift-off is up to 3.0 mm due to the increasement of the total transmission power.

Sc2O3 was successfully extracted and separated from Bayan Obo tailings by a CaCl2-reductive carbon powder-combinative roasting method. The optimum process condition was obtained through adjusting specific effect factors. It is found that Sc2O3 with the ratio of 87.51 % is leached out under roasting temperature of 800 °C for 2 h through adding 73 % CaCl2, and 20 % reductive carbon powder with liquid to solid ratio of 3. Moreover, the specific reaction mechanism during roasting process was investigated by thermogravimetric–differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD) techniques. The results show that the main phases (SiO2, CaF2 and NaFeSi2O6) as well as important phases (LiScSi2O6, REFCO3 and REPO4) would turn into new phases (CaFeSiO4, Fe, Ca3(PO4)2, NaCl, RE2O3 and Sc2O3) after complicated reactions, which effectively break up the original mineral compositions and activate the existing state of containing scandium matter, consequently facilitating the subsequent hydrochloric acid leaching process.

A novel electrochemical sensor for determining metronidazole (MNZ) is developed based on a composite structure of molecularly imprinted polymer (MIP) and multi-walled carbon nanotubes (MWCNTs). The morphology characterization by SEM displayed the successful deposition of polymeric layer on MWCNTs surface. A series of parameters including loading quantity of MWCNTs, pH value of polymerization system, and ratio of template and monomer are investigated and optimized during sensor preparation. It is clearly found that the MIP-decorated MWCNTs significantly enhance the electric signal response in MNZ measurement, giving rise to a remarkably low detection limit of 4.92 × 10−5 mg L−1 (S/N = 3), while the electro-synthesized MIP layer affords simultaneous identification and quantification of the target molecules by using Fe(CN)63−/4−as probe to indicate the current intensity. In addition, the established sensor is completely reusable and maintains excellent stability. These predominant properties enlist this hybrid electrode to exhibit high reliability for analyzing real samples and detection of MNZ directly in pharmaceutical dosage form and in fish tissue is successfully carried out without assistance of any separation techniques.

Convection is the main way of cooling and heat dissipation of mechanical devices. Because of its easy realization and high heat efficiency, convection is widely used in various electronic integrated devices or other purely mechanized devices. However, for some occasions with narrow space and high thermal radiation frequency, convective heat dissipation is often difficult to achieve good results. In this paper, the synthetic jet mode of dual mode double cavity resonance is studied, and combined with the Venturi tube, the flow of synthetic jet is supplemented by the Venturi effect to enhance the convection frequency and flow rate. Through the CFD optimization design and experimental verification, the Venturi tube outlet flow can be increased by 16.7%, and it has wide application occasions and good heat dissipation benefits.

Single-crystalline Li 4 Ti 5 O 12 nanorods have been successfully prepared through a molten salt method, followed by a precipitation method, and characterized with X-ray powder diffractometry, field-emission scanning electron microscopy, and transmission electron microscope. Their electrochemical properties have been studied by charge/discharge cycling and cyclic voltammetry. The results show that the single-crystalline Li 4 Ti 5 O 12 nanorods reveal high capacity, excellent rate capability and cycle stability. The discharge capacity up to 176.4 mAh g −1 at 0.1 C rate is achieved. When tested at 10 C rate, the first discharge capacity reaches 135.9 mAh g −1 , and the capacity retention is more than 61.5% after 1500 cycles. Furthermore, high rate capability Li 4 Ti 5 O 12 /LiMn 2 O 4 full cells have been made using Li 4 Ti 5 O 12 nanorods as the negative electrode, which display superior cycle stability at high rate. The discharge capacity and the mass energy density sequentially reach 40 mAh g −1 and 86.4 Wh kg −1 at 10 C rate, while the capacity retention is about 60% after 1000 cycles.

A LiMn 2 O 4 cathode material with novel porous spherical morphology exhibiting excellent electrochemical performance has been successfully prepared by using α-MnO 2 urchin-like structure as a self-sacrificial template. These cathode powders are characterized with X-ray powder diffractometry (XRD), field-emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller (BET) method and inductively coupled plasma emission spectrometry (ICP-AES). Furthermore, electrochemical properties have been studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge/discharge cycling at various current rates. The results reveal that the porous LiMn 2 O 4 spheres possess outstanding high rate capability and extremely high cycle stability at room temperature as well as elevated temperature. When tested at 10 C and 20 C rates, the first discharge capacities are up to 93.7 and 76.0 mAh g −1 . After 1000 cycles, the corresponding retention rates of capacities are more than 71% and 62% at room temperature. When cycled at 60 °C and 10 C rate, the first discharge capacity is 61.1 mAh g −1 between 3 and 4.5 V. After tested for 250 cycles at 60 °C, the retention rate of capacity is over 76%. This makes the porous LiMn 2 O 4 cathode a promising candidate for high-power lithium ion batteries which may be used in demanding application such as electric vehicles.

The removal of silicide-block-film is crucial for device stability, reliability and subsequent silicide formation. In this paper, various silicide block etch processes, i.e. dry and wet etch, were studied and compared. Possible plasma charging damage during dry etch might caused unstable PMOS threshold voltage (V"t"h) during H"2 annealing. The impacts of the plasma-process-induced-damage (PPID), including V"t"h shift, its channel length dependency, and its thermal stability were investigated. The PPID can be eliminated by reducing bias power and magnetic field, while sacrificing etch rate (ER) and equipment throughput. The main advantages of wet etch are immunity from PPID, and little surface damage resulting in uniform silicide formation. However, it also has disadvantages: buffered oxide etchant (BOE) leads to the appearance of poly pinholes, and diluted hydrofluoric acid (DHF) peels the photoresist (PR) off. Therefore, wet etch can only be used in the situation of short etching time such as the combined dry and wet etch.

Anode-supported solid oxide fuel cells (SOFCs) composed of NiO-SDC (Sm0.2Ce0.8O1.9) composite anode, thin tri-layer electrolyte, and La0.6Sr0.4Co0.8Fe0.2O3 (LSCF)-La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) composite cathode were fabricated. The thin 11 μm SDC/15 μm LSGM/13 μm SDC tri-layer electrolyte was prepared by centrifugal casting and co-firing technique. Cell tests in air as oxidant and humidified hydrogen as fuel show a maximum power density of 0.92 W /cm at 800°C. However, the open-circuit voltage (OCV) of these cells is 0.89 V which is lower than the Nernst potential. The above result is due to electronic conductivity in the LSGM layer, resulting from Ni impurities that entered during co-firing with the NiO-SDC anode. While the SDC buffer layers are introduced as buffer layers, impedance measurements indicate that both the ohmic resistance and the polarization resistance dominate the cell performance.

The objective of this study is to evaluate the influence of condensing heat recovery on the dynamic behavior and performance of air conditioners. The article includes a test procedure utilized to evaluate the condensing heat recovery system, relevant experimental results, a detail analysis of the mechanisms, and improvement measure on such a system. The experimental results indicate that although the condensing heat recovery has a negative effect on the cooling capacity at the start of the heat recovery process, the average cooling coefficient of performance (COP) of the system can be improved. The study also incorporates a control scheme of the electronic expansion valve (EEV) of the condensing heat recovery system. The experimental comparison between the EEV and the thermostatic expansion valve (TEV) demonstrates that the EEV has better performance in both stability and efficiency in the condensing heat recovery system.

In this paper, the complex behavior of saturation drain current (Idsat) dependence on channel width was investigated. We compared two types of devices and concluded that the variation of Idsat with changing width is determined by both the y-direction shallow trench isolation mechanical stress (y-stress) effect and the delta width effect. Moreover, a semi-empirical formula was proposed to describe the Idsat dependence on channel width, taking into account these two effects. To reduce the STI stress, we examined several process steps that may contribute to the stress development, and found that a high temperature post-liner-anneal step can obviously reduce the stress effect.