Search Results (330)

p-GaN gate enhancement-mode GaN High Electron Mobility Transistors (HEMTs) are promising normally off power devices, but their high-temperature reliability is strongly affected by the gate-contact scheme. This study compares Pd ohmic and Ni Schottky p-GaN gate HEMTs fabricated on the same GaN-on-Si epitaxial platform by combining temperature-dependent electrical characterization, post-temperature-dependent-test (TDT) room-temperature recovery analysis, and thermoreflectance thermal mapping. Electrical measurements were performed in a temperature range from room temperature to 500 °C using gate leakage, transfer, and output characteristics, while thermal maps were obtained before and after the TDT under identical bias conditions. The Pd ohmic devices exhibited a higher initial current drive but a larger operating gate-current penalty and greater degradation of normalized on-state characteristics at elevated temperature. After the TDT, reduced transconductance and maximum drain current were accompanied by weaker active-channel heating, indicating degradation-type cooling associated with reduced gate–channel modulation efficiency. In contrast, the Ni Schottky devices showed a lower gate-current penalty and better normalized output retention up to approximately 300 °C; however, post-TDT increases in transconductance and drain current occurred together with degraded subthreshold swing and persistent localized heating, indicating apparent on-state activation with weakened gate/depletion control. These results show that p-GaN gate reliability should be assessed through coupled electrical and thermal signatures rather than single electrical or thermal metrics. Full article

Background: Live-streaming e-commerce has emerged as a significant retail channel, especially in the apparel industry, characterized by high impulse-driven purchase rates and elevated product returns. Reverse logistics processes associated with these returns generate considerable environmental impacts that require systematic evaluation. Methods: This study performs a gate-to-gate Life Cycle Assessment (LCA) using SimaPro software, with a functional unit of 1 kg for one pair of returned jeans. Secondary inventory data were obtained primarily from the Ecoinvent database and supplemented with literature-based estimates for transport distances and packaging masses. Results: Key hotspots analyzed include transportation modes, packaging materials, and waste disposal pathways. Transportation mode selection was the dominant environmental hotspot, with air freight exhibiting the highest impacts across most midpoint and endpoint categories. Low-density polyethylene (LDPE) packaging and landfill disposal of textile waste were also major contributors to global warming, ozone formation, and resource depletion. Conclusions: The findings underscore the necessity of integrating Circular Supply Chain (CSC) principles into reverse logistics network design for live-streaming platforms. Optimizing transportation modes and packaging choices can effectively balance operational responsiveness with environmental sustainability. This study offers empirical evidence and practical decision-supporting insights for more sustainable return management in high-return digital retail environments. Full article

High-voltage short pulse generators play a critical role in medical and industrial applications. However, the presence of residual stored energy can pose significant electrical safety hazards. To mitigate these hazards, the implementation of rapid discharge mechanisms is imperative. To address the limitations of slow passive bleeders and auxiliary-dependent active circuits, and the issue of excessive size for compact pulse generators, this study proposes a self-powered, fast-response discharge topology utilizing cascaded depletion-mode NMOS transistors. The method utilizes the inherent normally-on characteristic of depletion-mode devices to ensure fail-safe activation during power loss, employing a self-biased feedback loop to regulate a constant discharge current. The theoretical models were validated through simulations and a hardware prototype testing a 1200 V/220 nF capacitor. The experimental results demonstrate the capability to successfully discharge 1200 V to a safe level within a span of one second. Additionally, the discharge time can be programmed within the range from 72 milliseconds to 1.02 s by adjusting the current-limiting resistor. In summary, the proposed topology offers a reliable, compact, and adjustable solution for high-voltage safety, addressing the limitations of conventional discharge technologies in terms of volume and speed. Full article

Cheese production generates large volumes of whey, and high-strength wastewater with elevated organic load, salinity, and nutrient content. Although whey contains valuable components including lactose, proteins, and minerals, approximately half of global production remains underutilized, contributing to eutrophication and oxygen depletion in aquatic ecosystems. Conventional physicochemical and biological treatment methods are limited by high operational costs, energy demands, and secondary waste generation. Microalgae-based bioremediation has emerged as a promising sustainable strategy for whey valorization, enabling simultaneous nutrient removal and biomass production. Through a focused review of the current literature, this study analyzes microalgal strains commonly applied in whey remediation, their cultivation modes (photoautotrophic, heterotrophic, and mixotrophic), nutrient uptake mechanisms, and operational conditions. The review highlights cultivation systems, biomass recovery techniques, and potential conversion of microalgal biomass into high value bioproducts, including biofuels, pigments, proteins, and biofertilizers. Critically, a major research gap exists: no studies systematically examine whey-grown microalgal biomass for bioplastic or film production, despite its elevated polysaccharide and protein content. Future development requires integrated biorefinery approaches, optimized cultivation strategies, and supportive policy frameworks to enable large-scale circular economy implementation within the dairy industry. Full article

Energy-harvesting (EH) AIoT systems enable long-term autonomous operation but suffer from time-varying energy availability, which makes stable learning difficult. In such environments, federated learning (FL) is prone to energy depletion (blackout), while continual learning is required to handle evolving data distributions, leading to a trade-off between energy stability and catastrophic forgetting. In this paper, we propose a stability-controlled continual federated learning framework that jointly regulates local training intensity and rehearsal usage based on the residual energy state. The proposed method is derived from a Lyapunov drift-plus-penalty formulation and implemented as a lightweight mode-based control policy. Simulation results using real solar energy traces show that the proposed method significantly reduces blackout while improving accuracy and mitigating forgetting compared to existing approaches. These results demonstrate the effectiveness of energy-aware joint control for stable continual federated learning in EH-AIoT systems. Full article

To address the urgent need for electronics operable in extremely high-temperature environments, this paper presents a novel three-terminal, dual-gate, lateral 4H-SiC n-channel depletion-mode junction field effect transistor (JFET) without a backside electrode. Featuring a fully planar electrode layout, the device eliminates the back-gate effect and significantly improves integration compatibility. Experimental results demonstrate stable DC operation up to 500 °C, with an intrinsic gain of 9.79 at room temperature and 6.01 at 500 °C. Comparison with TCAD simulations confirms excellent agreement in the key physical trends of threshold voltage drift and mobility degradation, though quantitative discrepancies are observed and attributed to process-induced parasitic effects such as non-ideal ohmic contacts and interface states. Analysis shows that the new structure broadens the channel depletion layer by optimizing the depletion profile, thereby suppressing channel-length modulation and improving both output resistance and gate control. This work not only provides an effective device platform for high-temperature 4H-SiC analog integrated circuits (ICs) but also deepens the understanding of process-performance correlations, offering clear guidance for process-oriented device optimization. The proposed structure serves as a foundation for developing fully planar, high-temperature 4H-SiC analog ICs with promising potential in aerospace, automotive, and energy exploration systems. Full article

This work presents a high-efficiency and linear Ka-band power amplifier (PA) designed in a $0.13$ $\mathsf{\mu }$m depletion-mode GaAs pHEMT process, targeting 5G phased-array systems. To minimize passive losses, the output matching network employs an all-transmission-line architecture. Phase mismatches among output branches are compensated directly within the interstage and output matching networks via tailored distributed and capacitive components. Device-level reliability is proactively addressed by maintaining adequate voltage headroom under worst-case load mismatch, based on voltage standing wave ratio (VSWR) analysis. The amplifier achieves a peak small-signal gain of $15.8$ dB at 27 GHz. Under continuous-wave excitation at 27 GHz, it delivers $32.9$ dBm output power at the 1-dB compression point with $32.8$% power-added efficiency (PAE), reaching a peak saturated output of $33.2$ dBm and $35.9$% PAE. When driven by a 64-QAM signal with a 250 MHz symbol rate, the PA maintains an average output power of $26.3$ dBm and an average PAE of $12.2$%, with an rms EVM of $3.4$% and an SNR of $25.5$ dB. Full article

The SAE J2841 utility factor (UF) estimates the fraction of driving expected to occur in charge-depleting (CD) mode for plug-in hybrid electric vehicles. Emerging in-use data suggest that real-world electric usage is lower than assumed, motivating a reassessment of how charging behavior and related factors should be incorporated into the UF curve. Using trip-level data from approximately 1000 PHEVs observed over one year, we develop a charging model that captures both population-level heterogeneity in charging frequency and day-to-day characteristic temporal patterns in individual charging. The charging behavior modeling is applied to NHTS driving data to generate UF curves spanning 5 to 200 miles (8 to 322 km) of CD range. When key behavioral features are included, the resulting CD driving fractions align closely with industry-provided data. Sensitivity analysis indicates that the assumed share of habitual non-chargers is among the most influential parameters affecting the gap between the original UF and in-use data. Multiple modeling approaches were used to explore the problem and compare results, including machine learning, logistic regression, and parametric methods. Additional factors such as blended CD operation and temperature effects are discussed within a modular framework for refining J2841. These findings inform ongoing discussions on PHEV utility representation in analytical and regulatory contexts. Full article

The depletion of natural river sand resources in the construction industry and the pollution caused by iron tailings storage in the steel industry are the two major challenges currently faced. The use of iron tailings in construction materials is widely regarded as one of the most sustainable and cost-effective approaches. Based on C30 concrete, 12 steel tube iron tailings sand (IOT) concrete columns with different IOT substitution rates were designed and fabricated in this paper, and axial compression test research was conducted on them; finite element simulations were conducted for comparison with the experimental results, focusing on the influences of IOT substitution rate (0–100%), steel pipe wall thickness (1–4 mm), and steel strength (Q235, Q355, Q390, Q420, Q460) on the bearing capacity of concreted steel tube columns were parametrically analyzed. By comparing the calculation methods of the bearing capacity of concrete-filled steel tube columns in five relevant standards, the calculation formula for the bearing capacity of IOT columns was corrected and obtained. The results show that the failure mode of the IOT column is similar to that of the ordinary column, and the steel tube wall has all undergone circumferential band shear buckling. As the replacement ratio of IOT increases, the load-bearing capacity of columns initially improves and then declines. The finite element analysis results show that the bearing capacity of the IOT column is directly proportional to the wall thickness of the steel pipe, and increasing the wall thickness of the steel pipe can effectively improve the bearing capacity of IOT columns. The discrepancy between the predicted and experimental bearing capacities of IOT columns obtained based on the revision of the “Technical Code for Concrete-filled Steel Tube Structures” (GB 50936-2014) is within 10%, which can effectively predict the load-bearing capacity of IOT columns within a certain range. Full article

Decarbonizing heavy-duty road freight transportation requires efficient energy management in zero-emission powertrains. This study investigates energy management strategies (EMSs) for a heavy-duty Fuel Cell Plug-in Hybrid Electric Vehicle (FC-PHEV). Rather than the typical charge-sustaining operation, these strategies are designed for charge-depleting operation, in which each route begins with a charged battery and ends at a lower state of charge (SOC), leveraging the vehicle’s plug-in capability. The EMSs are evaluated primarily in terms of energy consumption, while battery C-rate and fuel cell ramp rate are used as simple stress indicators for comparative analysis. A backward-facing vehicle model is developed to test several EMSs, including both optimization- and rule-based strategies. The Equivalent Consumption Minimization Strategy (ECMS) emerged as a promising option, motivating further testing with a forward-facing model and additional drive cycles. The simulation results show that ECMS consumed only 1.1% more energy than the global optimal solution found by Pontryagin’s Minimum Principle (PMP) and 7.5% less energy than a simple rule-based strategy, on average across five drive cycles. These results show that ECMS can be effective for a heavy-duty FC-PHEV operating in charge-depleting mode, extending its demonstrated applicability beyond charge-sustaining and light-duty vehicles. Full article

The obligate mutualism between Ficus and its pollinating wasps provides a suitable system to investigate these dynamics because it encompasses two contrasting pollination modes: active and passive. Here we compared pollen traits in an actively pollinated fig tree, Ficus citrifolia, and a passively pollinated species, F. obtusiuscula, examining pollen both at anther presentation and after deposition on the bodies of their pollinating wasps. Pollen morphology, hydration-related behavior, cytology, and reserve composition were characterized using scanning electron microscopy (conventional and modified), light and transmission electron microscopy, histochemical assays, and viability tests. Across species, pollen traits at anthesis showed broad overlap in morphology, viability and major reserve classes, indicating that these characteristics are not consistently predicted by pollination mode alone. In both species, pollen was bicellular, harmomegathic and highly viable at presentation, consistent with resilience during transport. The main divergence emerged after pollen transfer to the pollinator. In the actively pollinated species, pollen recovered from wasp thoracic pockets exhibited pronounced intracellular remodeling, including vacuolization, starch depletion, lipid redistribution and localized cytoplasmic degradation. By contrast, pollen of the passively pollinated species retained a comparatively stable cytological organization after transport despite changes in reserve distribution. These results suggest that the more pronounced cytoplasmic reorganization observed in the pollen of the actively pollinated species after deposition on the wasp body may represent a preparatory phase for rapid germination following pollination, reflecting the stronger dependence of larval development on successful flower fertilization in actively pollinated figs. More broadly, our study provides the first comparative account of pollen structural and cytophysiological dynamics on fig-wasp bodies, linking pollen cell biology to pollinator-mediated dispersal and highlighting how different pollination strategies may impose distinct selective pressures on male gametophytes. Full article

Bioactive glass (BAG) S53P4 is a clinically approved bone substitute with antibacterial, osteoconductive and osteostimulatory properties. Its antibacterial effect is associated with ion release, local pH elevation and osmolality, but the precise biochemical and biophysical mode-of-action is unclear. This study investigates the antibacterial mechanism of BAG S53P4 eluates. BAG eluates, collected at 2, 4, 8, and 24 h, eradicated Staphylococcus aureus. Elemental analysis revealed an early increase in concentrations of Si and Na, a later rise in Ca, depletion of P over time and rapid loss of Mg. Membrane disturbances occurred within 5 min, evident by permeability for SYTOX, aligning with time-kill kinetics for S. aureus and Bacillus subtilis. In B. subtilis, 2h-BAG-eluate induced rapid delocalization of marker proteins for cell division and DNA repair, signaling membrane potential collapse and nucleoid condensation. Transcriptomics revealed early transcription remodeling reflecting ionic and energetic imbalance, including disruption of central metabolism, redox homeostasis, and translational stability. Scanning electron microscopy revealed severe cell surface damage and particulate deposits on S. aureus. Transmission electron microscopy showed cell envelop disruptions and cytoplasmic leakage. Energy dispersive X-ray analysis identified Si on bacterial cell surface at 4 h and intracellular accumulation in punctured, empty cells at 24 h. Overall, BAG ionic dissolution products kill bacteria through a stepwise mechanism involving membrane damage, protein delocalization and metabolic impairment, accompanied by Si deposition on bacterial surfaces and loss of Mg. This finally leads to cell wall degradation, cytoplasmic content leakage and further Si deposition on the cells and inside cell ghosts. Full article

High-content cemented soils are critical for modern geotechnical technologies (e.g., pre-bored precast piles), yet their long-term durability remains underexplored. This study investigates the 28- to 365-day mechanical and microstructural evolution of high-content cemented silty clay under freshwater and seawater curing via UCS, SEM, MIP, and XRD. Under freshwater, cement content directly dictated strength, with the 8:2 mix reaching 24.31 MPa at 365 days. However, marginal efficiency analysis confirmed diminishing returns for excessive binder, establishing the 7:3 ratio as the optimal baseline. Seawater exposure induced a biphasic response: a 4.6% early strength gain at 28 days, followed by severe degradation (a 23.5% drop at 365 days). Concurrently, the failure mode shifted to macroscopic “pseudo-ductility,” with peak strain increasing from 2.37% to 3.04%. Crucially, a micro–macro inconsistency emerged: although seawater physically refined the pore structure (micropore proportion doubled to 30.2% at 90 days) via expansive salts filling mesopores, macroscopic strength declined. XRD confirmed this degradation coincides with severe long-term alkaline buffer (Ca(OH)₂) depletion. Consequently, lifecycle durability assessments for high-binder marine systems must not rely solely on physical metrics like porosity, but adopt a coupled multi-factor framework prioritizing chemical stability. Full article

Sexual reproduction is the predominant mode of reproduction in animals, and spermatogenesis is the fundamental step in this process. As the model organism for lepidopteran, the silkworm Bombyx mori exhibits typical dichotomous spermatogenesis, producing both nucleated (eupyrene) and anucleate (apyrene) sperm. Leucylaminopeptidases (LAPs), members of the M17 metalloprotease family, are characterized by their ability to cleave leucine residues from the N-terminus of peptides. In addition to this canonical function, they have been implicated in male fertility in mammals and Diptera. Nevertheless, whether LAPs are required for dimorphic spermatogenesis in Lepidoptera remains to be clarified. Here, we demonstrated that Sperm-Leucylaminopeptidase (S-LAP) plays vital roles in the silkworm eupyrene sperm development. Similar to the testis-specific expression pattern of eight S-LAPs in Drosophila melanogaster, BmS-LAP was also predominantly expressed in testis. Depletion of BmS-LAP via CRISPR/Cas9 system resulted in male sterility, while the fertility of female mutant was unaffected. Notably, male mutants displayed severe defects in the formation and migration of eupyrene sperm, whereas apyrene sperm development appeared normal. In addition, RNA-seq and qRT-PCR analyses demonstrated that spermatogenesis defects were associated with energy metabolism and flagellar assembly. Our study provides the first evidence that LAP is necessary for dimorphic spermatogenesis in Lepidopteran, offering new insights into the molecular basis of male infertility. Full article

Lithium-ion batteries in hybrid solar-grid systems experience complex electro-thermal dynamics and stochastic mode switching that threshold-based battery management systems fail to capture. This paper proposes a hybrid deviation detection framework that treats anomaly detection as a trajectory-consistency problem over a power-feasible Markov jump nonlinear system. A disturbance-robust invariant operating region is first established under explicit current bounds. A reachable-set equivalence is then derived, linking residual consistency to disturbance-augmented trajectory membership. Building on this structure, Isolation Forest empirically estimates the support of admissible electro-thermal trajectories, capturing nonlinear and mode-dependent behaviors not fully described by the analytical disturbance model. A unified sequential detection rule integrates structural constraint violations, model-based residual deviations, and empirical support inconsistencies into a coherent real-time monitor. The framework is validated on a hybrid solar-grid platform with a 6 W photovoltaic panel, a 3.7 V 1820 mAh lithium-ion battery, and a Raspberry Pi, collecting 3976 samples over four days. Results demonstrate early detection of depletion events and mode-transition anomalies before hard threshold violations, with zero false alarms during steady operation and an overall deviation rate of 4.8%, aligning with the configured contamination level. Early warning was observed at 20% state of charge, providing a 10% margin before the hardware threshold of 10%, while 88% of detected anomalies occurred in sequences, validating the persistence rule. Real-time inference required 47 ms per cycle with a 156 MB memory footprint, confirming edge deployment feasibility. Full article