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A Novel Faraday-Cage Inspired FSS Shield for Stable Resonance Performance Characteristics
摘要： In this latter, a novel Faraday cage inspired frequency selective surface (FSS) array is illustrated to patch-type periodic element. A metallic via has been used to stow the two patch conducting arrays printed on either side of the substrate. The intended application of the proposed electromagnetic (EM) structure is at microwave frequencies for improved bandwidth characteristics and stable resonance response. The structure shows a very stable resonance performance up to 60o oblique incident angle and 11.52% improvement in its fractional bandwidth. In addition, the simulation results of proposed design prove the validity of proposed structure for high microwave powers. Finally, the fabricated prototype along with experimental results of the Faraday cage array show the efficacy of proposed structural design.
关键词： Faraday cage,High power handling,Electromagnetic (EM) performance,Frequency Selective Surfaces (FSS),Substrate Integrated Waveguide (SIW)
更新于2025-09-10 09:29:36
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Thermoelectric performance of monolayer InSe improved by convergence of multivalley bands
摘要： We theoretically investigate a possibility of improving the thermoelectric performance of monolayer InSe through convergence of multivalley energy bands, in which some distinct valleys become almost degenerate. The convergence of energy bands is achieved by applying mechanical strain. We find that the thermoelectric power factor of monolayer InSe can be significantly enhanced by nearly a factor of 3 through the band convergence in both valence (p-type) and conduction (n-type) bands under a biaxial compressive stress of about 1.16 GPa. However, the maximum enhancement of the figure of merit ZT in the p-type and n-type InSe differs each other depending on how the valleys converge in each case. The optimal scenario is that the heavy valleys approach the light valleys in the band convergence, which leads to an increase in the power factor and, at the same time, a decrease in the thermal conductivity of an electron. This optimal condition can be obtained in the strained n-type InSe that gives the largest enhancement of ZT as high as 230% ZT of unstrained InSe. In contrast, the enhancement of ZT in the strained p-type InSe, which exhibits opposite valley convergence (light valleys joining heavy ones), gives only 26% ZT of unstrained InSe.
关键词： mechanical strain,thermoelectric performance,power factor,figure of merit,multivalley bands,monolayer InSe
更新于2025-09-10 09:29:36
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Preparation of ZnO nanoparticle-reinforced polyamide 6 composite by <i>in situ</i> -coproduced method and their properties
摘要： Polyamide 6/ZnO nanocomposites (noted as PA6/ZnO) were prepared by an in situ co-producing method, during which Zn2(OH)2CO3 decomposed into nano-ZnO in the process of the opening-ring polymerization of caprolactam at high temperature. Transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry were used to analyze the size and dispersive properties of nano-ZnO, the crystallization and melting properties, the thermal properties, and crystal structure of PA6/ZnO composite, respectively. The results showed that the nano-ZnO derived from Zn2(OH)2CO3 via in situ polymerization of PA6-ZnO was uniformly dispersed in PA6 matrix. However, the overall nano-ZnO crystallization rate and crystal size in the PA6 matrix were hindered by the bulky PA6 molecular chains. The mechanical properties were evaluated using universal tensile and impact testing instruments. The results revealed that PA6/ZnO composite with 0.2% nano-ZnO content possessed excellent tensile strength, enhanced by 75% in comparison with the pure PA6. The nano-ZnO had little influence on the impact strength of PA6.
关键词： friction property,mechanical performance,nanocomposites,polyamide 6,nano-ZnO,polyamides,composite
更新于2025-09-09 09:28:46
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Effects of Au nanoparticles and ZnO morphology on the photocatalytic performance of Au doped ZnO/TiO<sub>2</sub> films
摘要： Au doped ZnO nanocomposite films on TiO2 seeding layer (AuZ/T) were fabricated by hydrothermal processing and their photocatalytic performance was investigated. It could be found that the AuZ/T with micrometer(μm)-sized, lying ZnO bulks revealed optimal photocatalytic performance toward methyl orange (MO) under simulated sunlight, whose apparent degradation rate constant Kapp of 1.31 was about 20% higher compared to that of ZnO/TiO2 and 3 times higher compared to that of ZnO. The Au nanoparticles, TiO2 seeding layer and hydrothermal processing time imposed vital influence on the morphology of ZnO nanostructures, which played key roles in the formation of ZnO/TiO2 heterojunction and charge transfer(CT) inside it, as demonstrated by kinetics of transient photoluminescence (PL) decaying. The incorporation of Au nanoparticles not only induced the variations of ZnO crystallinity and reduction of ZnO band gap (Eg), but also generated the Schottky heterojunction of metal-semiconductor, which would be beneficial to the CT inside nanocomposite films and separation of photo-generated electron-hole pairs, as verified by the remarkable PL suppression. The mechanism responsible for photocatalysis enhancement, which was resulted from the hybrid effects of Au nanoparticles and the ZnO morphology was discussed in details.
关键词： photocatalytic performance,Au doped ZnO,heterojunction,TiO2
更新于2025-09-09 09:28:46
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Enhanced biosynthesis of CdS nanoparticles through Arabidopsis thaliana phytochelatin synthase-modified Escherichia coli with fluorescence effect in detection of pyrogallol and gallic acid
摘要： In this work, CdS nanoparticles (CdS NPs) biosynthesized through Arabidopsis thaliana phytochelatin synthase-modified Escherichia coli (CdS/AtPCS1-E. coli) with fluorescence (FL) performance for detection of pyrogallol and gallic acid was investigated. Through expression of the AtPCS1 gene inside E. coli cells by pET28b vector, biosynthesis of CdS NPs was greatly enhanced due to generation of phytochelatins (PCs, (γ-Glu-Cys)n-Gly, n ≥ 2) for efficient capture of Cd2+. The expression of AtPCS1 and concentration of glutathione (GSH) and PCs were detected by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high performance liquid chromatography (HPLC), respectively. The morphology and component were checked through scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). FL effect with different experimental conditions were examined. In addition, it is also applied to determination of pyrogallol and gallic acid. These results revealed that multifunctional PCs could effectively facilitate biosynthesis of CdS NPs with higher yield, better distribution and lower cost while stronger FL intensity could be obtained for quantitative analysis.
关键词： CdS nanoparticles,Escherichia coli,Phytochelatin,Fluorescence performance,Biosynthesis
更新于2025-09-09 09:28:46
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RF Performance of Al0.85Ga0.15N/Al0.70Ga0.30N High Electron Mobility Transistors with 80 nm Gates
摘要： Al-rich AlGaN-channel high electron mobility transistors (HEMTs) with 80 nm long gates and 85% (70%) Al in the barrier (channel) were evaluated for RF performance. DC characteristics include a maximum current of 160 mA/mm with transconductance of 24 mS/mm, limited by source and drain contacts, and an on/off current ratio of 109. fT of 28.4 GHz and fMAX of 18.5 GHz were determined from small-signal S-parameter measurements. Output power density of 0.38 W/mm was realized at 3 GHz in a power sweep using on-wafer load pull techniques.
关键词： high electron mobility transistor,Ultra-wide-bandgap,RF performance,HEMT,aluminum gallium nitride
更新于2025-09-09 09:28:46
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Porous graphitic carbon nitride with controllable nitrogen vacancies: As promising catalyst for enhanced degradation of pollutant under visible light
摘要： Carbon nitride (CN) materials are considered as promising photocatalysts due to the advantages of easy availability and visible light absorption. However, wide band gap and high recombination rates of electron-hole pairs of conventional CN materials remain the “bottleneck” of the photocatalysts. Therefore, it is necessary to develop an efficient strategy to narrow band gap of CN and accelerate its charge transfer. In addition, the introduction of nitrogen (N) vacancies is an efficient strategy to narrow band gap and reduce recombination rates of electron-hole pairs. Herein, a novel triazole ring-based graphite carbon nitride (g-C3N5) is developed by one step pathway of NaOH-assisted condensation of triazole rings for the first time. It is found that NaOH can control N vacancies and band gap of g-C3Nx. Meanwhile, the N vacancies of g-C3Nx gradually increase with the increasing concentration of NaOH in the range of 0.005-0.1 g, suppressing the recombination of photogenerated electron-hole pairs. The proposed g-C3Nx exhibits outstanding photocatalytical and photoelectrochemical performance. Therefore, the study highlights the significance of N vacancies in enhancing the photocatalytical and photoelectrochemical performance of promising g-C3N5.
关键词： outstanding photocatalytical and photoelectrochemical performance,g-C3N5,NaOH-treated condensation of triazole rings,controllable N vacancies
更新于2025-09-09 09:28:46
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Using the Moebius Transformation to Predict the Effect of Source Impedance on Insertion Loss
摘要： Knowledge of the strength and internal impedance of the sound source is essential to predict the overall acoustic performance of an exhaust or intake system. Source impedance is sometimes measured directly using a strong external source. At other times, a suitable external source is difficult to identify and an indirect multi-load method is used to determine source impedance and strength. Data can be processed using the commonly used circuit analogy or via a similar wave decomposition model. In this work, the two processing schemes are used to determine the source impedance and strength of a diesel engine. Results are compared to one another and to assumed source impedances and equations in the literature for source strength. The sound pressure in the exhaust is predicted from the measured source strength and impedance and compared with measurement. There is good agreement especially at the first few harmonics of the firing frequency. It is then observed that the equation relating the source impedance to the acoustic response is in the form of the Moebius transformation, which maps straight lines or circles in one complex domain into straight lines or circles in another complex domain. It is demonstrated that the range of source impedance, defined as an outline in the complex plane, can be transformed to a corresponding outline of the muffler insertion loss complex amplitude, and the minimum and maximum insertion loss can be computed at a given frequency. This permits the expected insertion loss range to be plotted as a function of frequency.
关键词： insertion loss,Moebius transformation,source impedance,acoustic performance,diesel engine
更新于2025-09-09 09:28:46
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Multi-objective Optimization of Rotary Ultrasonic Machining Parameters for Quartz Glass Using Taguchi-Grey Relational Analysis (GRA)
摘要： Rotary ultrasonic machining has the capability to process the materials which are very hard, brittle and electrically non-conductive, with efficiency and cost-effectiveness. The current investigation is focused on the use of Taguchi-Grey relational analysis to improve the machining performance of Rotary ultrasonically machined quartz glass. Ideal machining parameters were calculated by grey relational grade calculated in grey relational analysis which was designed for simultaneous optimization of material removal rate and surface roughness. The rotary ultrasonic machining parameters setting with tool rotational speed of 5000 rpm, tool feedrate of 0.75 mm/min, and ultrasonic power of 55% were found to have the highest grey relation grade resulting in the high material removal rate and low surface roughness of the processed material. The tool feed rate was found to be the most critical parameter followed by ultrasonic power and tool rotational speed on the rotary ultrasonic machining characteristics. Confirmatory experiments were also executed to authenticate the forecasted results obtained from the Taguchi-Grey relational analysis. Furthermore, the microstructural investigation was carried out to comprehend the mechanism of material removal in the rotary ultrasonic machining of quartz glass at optimum parameter setting. It was found that the material was removed in the brittle mode and abrasion during the machining at optimum parameter setting. The sharp cutting edges of the diamond grits have caused the abrasive wear and brittle fracture of the quartz material. The interlinking of the cracks results in the pullout of the grains and consequently deeper grooves are formed on the machined surface.
关键词： RUM,Fused silica,Taguchi method,Machining performance,Grey relational analysis,Microstructural investigation
更新于2025-09-09 09:28:46
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Tungsten doped M-phase VO2 mesoporous nanocrystals with enhanced comprehensive thermochromic properties for smart windows
摘要： The phase transition temperature (~ 68 oC) of M-VO2 film can be lowered significantly by tungsten (W) doping into the crystal lattice of VO2 due to the reduction of the strength of V-V pair interaction. However, W doping was always coupled with a serious weakening of luminous transmittance and solar modulation efficiency because W dopants can increase the electron concentration of VO2 film. Herein, the simultaneous introduction of W dopants and mesopores into M-VO2 nanocrystals was employed to prepare VO2 film. Interestingly, the obtained 0.4 at% W-doped mesoporous VO2 nanocrystals based composite films exhibited enhanced comprehensive thermochromic performance with excellent solar modulation efficiency (ΔTsol = 11.4%), suitable luminous transmittance (Tlum = 61.6%) and low phase transition temperature around 43 oC, much lower than 65.3 oC of undoped VO2. It was demonstrated that the lower phase transition temperature of VO2 can be primarily attributed to abundant lattice distortion after W doping, whereas the mesoporous structure can facilitate the uniform distribution of W dopants in VO2 nanocrystals, enhance the luminous transmittance and guarantee enough VO2 nanocrystals in the composite film to keep relatively high solar modulation efficiency. Therefore, this work can provide a new way to balance the three important parameters for the thermochromic performance of VO2 film (ΔTsol, Tlum and Tc) and probably promote the application of VO2 nanocrystals in the energy efficient windows.
关键词： thermochromic performance,phase transition temperature,mesoporous structure,W-doped VO2
更新于2025-09-09 09:28:46