Microstructure and properties of Cu matrix composites reinforced with surface-modified Kovar particles

The thermal conductivity of Cu/Kovar composites was improved by suppressing element diffusion at the interfaces through the formation of FeWO_(4)coating on the Kovar particles via vacuum deposition.Cu matrix composites reinforced with unmodified(Cu/Kovar)and modified Kovar(Cu/Kovar@)particles were prepared by hot pressing.The results demonstrate that the interfaces of Cu/FeWO_(4)and FeWO_(4)/Kovar in the Cu/Kovar@composites exhibit strong bonding,and no secondary phase is generated.The presence of FeWO_(4)impedes interfacial diffusion within the composite,resulting in an increase in grain size and a decrease in dislocation density.After surface modification of the Kovar particle,the thermal conductivity of Cu/Kovar@composite is increased by 110%from 40.6 to 85.6 W·m^(-1)·K^(-1).Moreover,the thermal expansion coefficient of the Cu/Kovar@composite is 9.8×10^(-6)K^(-1),meeting the electronic packaging requirements.

Study of leakage current degradation based on stacking faults expansion in irradiated SiC junction barrier Schottky diodes

A comprehensive investigation was conducted to explore the degradation mechanism of leakage current in SiC junction barrier Schottky(JBS)diodes under heavy ion irradiation.We propose and verify that the generation of stacking faults(SFs)induced by the recombination of massive electron-hole pairs during irradiation is the cause of reverse leakage current degradation based on experiments results.The irradiation experiment was carried out based on Ta ions with high linear energy transfer(LET)of 90.5 MeV/(mg/cm^(2)).It is observed that the leakage current of the diode undergoes the permanent increase during irradiation when biased at 20%of the rated reverse voltage.Micro-PL spectroscopy and PL micro-imaging were utilized to detect the presence of SFs in the irradiated SiC JBS diodes.We combined the degraded performance of irradiated samples with SFs introduced by heavy ion irradiation.Finally,three-dimensional(3D)TCAD simulation was employed to evaluate the excessive electron-hole pairs(EHPs)concentration excited by heavy ion irradiation.It was observed that the excessive hole concentration under irradiation exceeded significantly the threshold hole concentration necessary for the expansion of SFs in the substrate.The proposed mechanism suggests that the process and material characteristics of the silicon carbide should be considered in order to reinforcing against the single event effect of SiC power devices.

Spatial Distribution Feature Extraction Network for Open Set Recognition of Electromagnetic Signal

This paper proposes a novel open set recognition method,the Spatial Distribution Feature Extraction Network(SDFEN),to address the problem of electromagnetic signal recognition in an open environment.The spatial distribution feature extraction layer in SDFEN replaces convolutional output neural networks with the spatial distribution features that focus more on inter-sample information by incorporating class center vectors.The designed hybrid loss function considers both intra-class distance and inter-class distance,thereby enhancing the similarity among samples of the same class and increasing the dissimilarity between samples of different classes during training.Consequently,this method allows unknown classes to occupy a larger space in the feature space.This reduces the possibility of overlap with known class samples and makes the boundaries between known and unknown samples more distinct.Additionally,the feature comparator threshold can be used to reject unknown samples.For signal open set recognition,seven methods,including the proposed method,are applied to two kinds of electromagnetic signal data:modulation signal and real-world emitter.The experimental results demonstrate that the proposed method outperforms the other six methods overall in a simulated open environment.Specifically,compared to the state-of-the-art Openmax method,the novel method achieves up to 8.87%and 5.25%higher micro-F-measures,respectively.

Device design principles and bioelectronic applications for flexible organic electrochemical transistors

Organic electrochemical transistors(OECTs) exhibit significant potential for applications in healthcare and human-machine interfaces, due to their tunable synthesis, facile deposition, and excellent biocompatibility. Expanding OECTs to the fexible devices will significantly facilitate stable contact with the skin and enable more possible bioelectronic applications. In this work,we summarize the device physics of fexible OECTs, aiming to offer a foundational understanding and guidelines for material selection and device architecture. Particular attention is paid to the advanced manufacturing approaches, including photolithography and printing techniques, which establish a robust foundation for the commercialization and large-scale fabrication. And abundantly demonstrated examples ranging from biosensors, artificial synapses/neurons, to bioinspired nervous systems are summarized to highlight the considerable prospects of smart healthcare. In the end, the challenges and opportunities are proposed for fexible OECTs. The purpose of this review is not only to elaborate on the basic design principles of fexible OECTs, but also to act as a roadmap for further exploration of wearable OECTs in advanced bio-applications.

Proteomic response of Phaeocystis globosa to nitrogen limitation

Phaeocystis globosa is an important unicellular eukaryotic alga that can also form colonies.P.globosa can cause massive harmful algal blooms and plays an important role in the global carbon or sulfur cycling.Thus far,the ecophysiology of P.globosa has been investigated by numerous studies.However,the proteomic response of P.globosa to nitrogen depletion remains largely unknown.We compared four protein preparation methods of P.globosa for two-dimensional electrophoresis(2-DE)(Urea/Triton X-100 with trichloroacetic acid(TCA)/acetone precipitation;TCA/acetone precipitation;Radio Immuno Precipitation Assay(RIPA)with TCA/acetone precipitation;and Tris buffer).Results show that the combination of RIPA with TCA/acetone precipitation had a clear gel background and showed the best protein spot separation effect,based on which the proteomic response to nitrogen depletion was studied using 2-DE.In addition,we identified six differentially expressed proteins whose relative abundance increased or decreased more than 1.5-fold(P<0.05).Most proteins could not be identified,which might be attributed to the lack of genomic sequences of P.globosa.Under nitrogen limitation,replication protein-like,RNA ligase,and sn-glycerol-3-phosphate dehydrogenase were reduced,which may decrease the DNA replication level and ATP production in P.globosa cells.The increase of endonucleaseⅢand transcriptional regulator enzyme may affect the metabolic and antioxidant function of P.globosa cells and induce cell apoptosis.These findings provide a basis for further proteomic study of P.globosa and the optimization of protein preparation methods of marine microalgae.

Refiector Deformation Measurement and Correction Methodology of Large Antenna Based on Phased Array Feed

To solve the problem of time-consuming measurement and correction of large antennas’reflector deformation,a new microwave holography methodology based on a Phased Array Feed(PAF)is proposed.Starting from the known expression of receiving signals in microwave holography,the theory of PAF holography is derived through Geometrical Optics.Reflector deformation,as well as pointing deviation and subreflector offset,can be calculated out by applying the derived equations.A measurement and correction system based on PAF holography is depicted,and two kinds of measurement methods are illustrated.The proposed measurement methodology is verified by numerical simulation,and its measurement error is analyzed.The results indicate that our proposed methodology is feasible,especially for Cassegrain antennas.

Selection of Negative Charged Acidic Polar Additives to Regulate Electric Double Layer for Stable Zinc Ion Battery

Zinc-ion batteries are promising for large-scale electrochemical energy storage systems,which still suffer from interfacial issues,e.g.,hydrogen evolution side reaction(HER),self-corrosion,and uncontrollable dendritic Zn electrodeposition.Although the regulation of electric double layer(EDL)has been verified for interfacial issues,the principle to select the additive as the regulator is still misted.Here,several typical amino acids with different characteristics were examined to reveal the interfacial behaviors in regulated EDL on the Zn anode.Negative charged acidic polarity(NCAP)has been unveiled as the guideline for selecting additive to reconstruct EDL with an inner zincophilic H_(2)O-poor layer and to replace H_(2)O molecules of hydrated Zn^(2+)with NCAP glutamate.Taking the synergistic effects of EDL regulation,the uncontrollable interface is significantly stabilized from the suppressed HER and anti-self-corrosion with uniform electrodeposition.Consequently,by adding NCAP glutamate,a high average Coulombic efficiency of 99.83%of Zn metal is achieved in Zn|Cu asymmetrical cell for over 2000 cycles,and NH4V4O10|Zn full cell exhibits a high-capacity retention of 82.1%after 3000 cycles at 2 A g^(-1).Recapitulating,the NCAP principle posted here can quicken the design of trailblazing electrolyte additives for aqueous Zn-based electrochemical energy storage systems.

Computational Investigation on the Surface Electronic Density, Morphology and Detonation Property of 1,1-Diamino-2,2-dinitroethylene (FOX-7) Crystal

The present study constructed and optimized FOX-7 crystal using a novel technique including grand canonical monte carlo （GCMC）, density functional theory （DFT） and molecular dynamics （MD） methods. Therein, the crystal density, atomic and electronic actions were considered. The results showed that the 1.96 g.cm-3 FOX-7 crystal has the highest stability and detonation properties, such as the total crystal energy, surface electronic density, friction sensitivity, detonation pressure, and so on. These results are close to the experimental data.

Effects of Eu_2O_3 doping on microstructural and electronic properties of ZnO Bi_2O_3-based varistor ceramics prepared by high-energy ball milling

ZnO-Bi2O3-based varistor ceramics doped with EU2O3 in a range from 0 to 0.4% were obtained by high-energy ball milling and fired at 900-1000 ℃ for 2 h. XRD and SEM were applied to determine the phases and microstructure of the varistor ceramics. A DC parameter instrument was applied to investigate the electronic properties and V-I characteristics. The XRD analysis of Eu2O3-doped ZnO-Bi2O3-based varistor ceramics shows that the ZnO, Eu-containing Bi-rich, Zn7Sb2O12-type spinel and Zn2Bi3Sb3O14-type which is the pyrochlore phase are present. With increasing Eu2O3 content, the average size of ZnO grain firstly decreases and then increases. The grain boundary defect model was particularly used to explain the excellent nonlinearity of ZnO-Bi2O3-based varistor ceramics with the addition of0.1% Eu2O3 and sintered at 950 ℃.

Enhancement of electroluminescent properties of organic optoelectronic integrated device by doping phosphorescent dye

Organic optoelectronic integrated devices（OIDs） with ultraviolet（UV） photodetectivity and different color emitting were constructed by using a thermally activated delayed fluorescence（TADF） material 4, 5-bis（carbazol-9-yl）-1, 2-dicyanobenzene（2 CzPN） as host. The OIDs doping with typical red phosphorescent dye [tris（1-phenylisoquinoline）iridium（Ⅲ）, Ir（piq）3], orange phosphorescent dye {bis[2-（4-tertbutylphenyl）benzothiazolato-N,C-（2＇）]iridium（acetylacetonate）,（tbt）2 Ir（acac）}, and blue phosphorescent dye [bis（2, 4-di-fluorophenylpyridinato）-tetrakis（1-pyrazolyl）borate iridium（Ⅲ）, FIr6] were investigated and compared. The（tbt）2 Ir（acac）-doped orange device showed better performance than those of red and blue devices, which was ascribed to more effective energy transfer. Meanwhile, at a low dopant concentration of 3 wt.%, the（tbt）2 Ir（acac）-doped OIDs showed the maximum luminance, current efficiency, power efficiency of 70786 cd/m^2, 39.55 cd/A, and 23.92 lm/W, respectively, and a decent detectivity of 1.07 × 10^11 Jones at a bias of -2 V under the UV-350 nm illumination. This work may arouse widespread interest in constructing high efficiency and luminance OIDs based on doping phosphorescent dye.

Crystal plane induced in-situ electrochemical activation of manganese-based cathode enable long-term aqueous zinc-ion batteries

Rapid capacity decay and sluggish reaction kinetics are major barriers hindering the applications of manganese-based cathode materials for aqueous zinc-ion batteries.Herein,the effects of crystal plane on the in-situ transformation behavior and electrochemical performance of manganese-based cathode is discussed.A comprehensive discussion manifests that the exposed(100)crystal plane is beneficial to the phase transformation from tunnel-structured MnO_(2) to layer-structured ZnMn_(3)O_(7)·3H_(2)O,which plays a critical role for the high reactivity,high capacity,fast diffusion kinetics and long cycling stability.Additionally,a two-stage zinc storage mechanism can be demonstrated,involving continuous activation reaction and phase transition reaction.As expected,it exhibits a high capacity of 275 mAh g^(-1)at 100 mA g^(-1),a superior durability over 1000 cycles and good rate capability.This study may open new windows toward developing advanced cathodes for ZIBs,and facilitate the applications of ZIBs in large-scale energy storage system.

Perspectives in Electrochemical in situ Structural Reconstruction of Cathode Materials for Multivalent-ion Storage

Multivalent-ion(such as Zn^(2+),Mg^(2+),Al^(3+))batteries are considered as a prospective alternative for large-scale energy storage.However,the main problem of cathode materials for multivalent-ion batteries is the sluggish diffusion of multivalent ions.Many cathode materials will self-adjust under electrochemical conditions to achieve the optimal state for multivalent-ion storage.In this review,the significant role of electrochemical in situ structural reconstruction of cathode materials is suggested.The types,basic characteristics,and formation mechanisms of reconstructed phases have been systematically discussed and commented.The most important insight we pointed out is that the cathode materials with loose structures after in situ electrochemical activation are conducive to the reversible diffusion of multivalent ions.Moreover,several crucial issues of electrochemical activation and reconstruction were further analyzed and discussed.The challenges and future perspectives are presented in the final section.

Improved microwave dielectric properties of MgAl_(2)O_(4)spinel ceramics through(Li_(1/3)Ti_(2/3))^(3+)doping

A series of nominal compositions MgAl_(2-x)(Li_(1/3)Ti_(2/3))_(x)O_(4)(x=0,0.04,0.08,0.12,0.16,and 0.20)ceramics were successfully prepared via the conventional solid-state reaction route.The phase compositions,microstructures,and microwave dielectric properties were investigated.The results of x-ray diffraction(XRD)and scanning electron microscopy(SEM)showed that a single phase of MgAl_(2-x)(Li_(1/3)Ti_(2/3))_(x)O_(4)ceramics with a spinel structure was obtained at x≤0.12,whereas the second phase of MgTi_(2)O_(5)appeared when x>0.12.The cell parameters were obtained by XRD refinement.As the x values increased,the unit cell volume kept expanding.This phenomenon could be attributed to the partial substitution of(Li_(1/3)Ti_(2/3))^(3+)for Al^(3+).Results showed that(Li_(1/3)Ti_(2/3))^(3+)doping into MgAl_(2)O_(4)spinel ceramics effectively reduced the sintering temperature and improved the quality factor(Q_f)values.Good microwave dielectric properties were achieved for a sample at x=0.20 sintering at 1500℃in air for 4 h:dielectric constantε_(r)=8.78,temperature coefficient of resonant frequencyτ_(f)=-85 ppm/℃,and Q_(f)=62300 GHz.The Q_(f)value of the x=0.20 sample was about 2 times higher than that of pure MgAl_(2)O_(4)ceramics(31600 GHz).Thus,MgAl_(2-x)(Li_(1/3)Ti_(2/3))_(x)O_(4)ceramics with excellent microwave dielectric properties can be applied to 5G communications.

Synergistic Effect of Dual-Doped Carbon on MO_(2)C Nanocrystals Facilitates Alkaline Hydrogen Evolution

Molybdenum carbide(MO_(2)C)materials are promising electrocatalysts with potential applications in hydrogen evolution reaction(HER)due to low cost and Pt-like electronic structures.Nevertheless,their HER activity is usually hindered by the strong hydrogen binding energy.Moreover,the lack of water-cleaving site's makes it difficult for the catalysts to work in alkaline solutions.Here,we designed and synthesized a B and N dual-doped carbon layer that encapsulated on MO_(2)C nanocrystals(MO_(2)C@BNC)for accelerating HER under alkaline condition.The electronic interactions between the MO_(2)C nanocrystals and the multiple-doped carbon layer endow a near-zero H adsorption Gibbs free energy on the defective C atoms over the carbon shell.Meanwhile,the introduced B atoms afford optimal H_2O adsorption sites for the water-cleaving step.Accordingly,the dual-doped MO_(2)C catalyst with synergistic effect of non-metal sites delivers superior HER performances of a low overpotential(99 mV@10 mA cm^(-2))and a small Tafel slope(58.1 mV dec^(-1))in 1 M KOH solution.Furthermore,it presents a remarkable activity that outperforming the commercial 10%Pt/C catalyst at large current density,demonstrating its applicability in industrial water splitting.This study provides a reasonable design strategy towards noble-metal-free HER catalysts with high activity.

Cavitation recognition of axial piston pumps in noisy environment based on Grad-CAM visualization technique

The cavitation in axial piston pumps threatens the reliability and safety of the overall hydraulic system.Vibration signal can reflect the cavitation conditions in axial piston pumps and it has been combined with machine learning to detect the pump cavitation.However,the vibration signal usually contains noise in real working conditions,which raises concerns about accurate recognition of cavitation in noisy environment.This paper presents an intelligent method to recognise the cavitation in axial piston pumps in noisy environment.First,we train a convolutional neural network(CNN)using the spectrogram images transformed from raw vibration data under different cavitation conditions.Second,we employ the technique of gradient-weighted class activation mapping(Grad-CAM)to visualise class-discriminative regions in the spectrogram image.Finally,we propose a novel image processing method based on Grad-CAM heatmap to automatically remove entrained noise and enhance class features in the spectrogram image.The experimental results show that the proposed method greatly improves the diagnostic performance of the CNN model in noisy environments.The classification accuracy of cavitation conditions increases from 0.50 to 0.89 and from 0.80 to 0.92 at signal-to-noise ratios of 4 and 6 dB,respectively.

Optoelectronic properties analysis of silicon light-emitting diode monolithically integrated in standard CMOS IC

Si p^+n junction diodes operating in the mode of avalanche breakdown are capable of emitting light in the visible range of 400-900 nm. In this study, to realize the switching speed in the GHz range, we present a transient model to shorten the carrier lifetime in the high electric field region by accumulating carriers in both p and n type regions. We also verify the optoelectronic characteristics by disclosing the related physical mechanisms behind the light emission phenomena. The emission of visible light by a monolithically integrated Si diode under the reverse bias is also discussed. The light is emitted as spatial sources by the defects located at the p-n junction of the reverse-biased diode. The influence of the defects on the electrical behavior is manifested as a current-dependent electroluminescence.

Coupling Modeling for Functional Surface of Electronic Equipment

High performance electromechanical equipment is widely used in various fields, such as national defense, industry and so on [ 1]. In addition, the technical level of high performance electromechanical equipment is the embodiment of the national level of science and technology.

Analytical transient phase change heat transfer model of wearable electronics with a thermal protection substrate

As thermal protection substrates for wearable electronics,functional soft composites made of polymer materials embedded with phase change materials and metal layers demonstrate unique capabilities for the thermal protection of human skin.Here,we develop an analytical transient phase change heat transfer model to investigate the thermal performance of a wearable electronic device with a thermal protection substrate.The model is validated by experiments and the finite element analysis(FEA).The effects of the substrate structure size and heat source power input on the temperature management efficiency are investigated systematically and comprehensively.The results show that the objective of thermal management for wearable electronics is achieved by the following thermal protection mechanism.The metal thin film helps to dissipate heat along the in-plane direction by reconfiguring the direction of heat flow,while the phase change material assimilates excessive heat.These results will not only promote the fundamental understanding of the thermal properties of wearable electronics incorporating thermal protection substrates,but also facilitate the rational design of thermal protection substrates for wearable electronics.

Residual Strain and Electronic Characteristics of Si-doped GaN

The residual strain and the damage induced by Si implantation in GaN samples have been studied, as well as the electronic characteristics. These as-grown samples are implanted with different doses of Si（1 × 10^14 cm^-2, 1×10^15 cm^-2 or ] × 10^16 cm^-2, ]00 keV） and following annealed by rapid thermal anneal（RTA） at 1 000℃ or 1 100℃ for 60 s. High resolution X-ray diffractometer（HRXRD） measurement reveals that the damage peak induced by the implantation appears and increases with the rise of the impurity dose, expanding the crystal lattice. The absolute value of biaxial strain decreases with the increase of the annealing temperature for the same sample. RT-Hall test reveals that the sample annealed at 1 100℃ acquires higher mobility and higher carrier density than that annealed at 1 000 ℃, which reflects that the residual strain（or residual stress） is the main scattering factor. And the sample C3（1 × 10^16 cm^-2 and annealed at 1100 ℃） acquires the best electronic characteristic with the carrier density of 3.25 × 10^19 cm^-3 and the carrier mobility of 31 cm2/（V·S）.

Design optimization of high breakdown voltage vertical GaN junction barrier Schottky diode with high-K/low-K compound dielectric structure

A vertical junction barrier Schottky diode with a high-K/low-K compound dielectric structure is proposed and optimized to achieve a high breakdown voltage(BV).There is a discontinuity of the electric field at the interface of high-K and low-K layers due to the different dielectric constants of high-K and low-K dielectric layers.A new electric field peak is introduced in the n-type drift region of junction barrier Schottky diode(JBS),so the distribution of electric field in JBS becomes more uniform.At the same time,the effect of electric-power line concentration at the p-n junction interface is suppressed due to the effects of the high-K dielectric layer and an enhancement of breakdown voltage can be achieved.Numerical simulations demonstrate that GaN JBS with a specific on-resistance(R_(on,sp)) of 2.07 mΩ·cm^(2) and a BV of 4171 V which is 167% higher than the breakdown voltage of the common structure,resulting in a high figure-of-merit(FOM) of 8.6 GW/cm^(2),and a low turn-on voltage of 0.6 V.