Search Results (45)

The substantially lower breakdown electric field of Si compared to GaN necessitates thick buffer layers in Si-based GaN power devices for medium-voltage applications, significantly increasing cost. Recently, sapphire substrates, offering high electrical insulation and excellent mechanical strength, have emerged as a promising alternative. In this work, we demonstrate a CMOS-compatible process for sapphire-based GaN MIS-HEMTs utilizing a thin buffer layer. The fabricated devices with a W_G of 20.4 mm and an L_GD of 24 μm achieve a high off-state breakdown voltage >1650 V and a maximum on-state current > 4.1 A, with tight statistical distributions of V_TH and R_ON across the wafer. Furthermore, statistical characterization results of dynamic R_ON and leakage current under electrical stress conditions at both room temperature and 150 °C, confirm operational viability at high temperatures. Finally, long-term reliability for 650 V operation is validated by high-temperature reverse bias (HTRB) accelerated aging tests. Full article

This paper presents, for the first time, the structure-dependent parameter trade-off optimization on figure-of-merit (R_onC_off) and power compression of AlGaN/GaN high electron mobility transistors (HEMTs) for radio frequency (RF) switch applications. For GaN HEMTs operating in switching mode, it was demonstrated that R_onC_off can be effectively reduced by increasing the gate foot length (L_{g_foot}), decreasing the gate cap length (L_{g_cap}), reducing the gate bias resistance (r_g), and adopting a high work function metal for the gate electrode (Φ_g). However, these parameter adjustments affect power compression and R_onC_off in opposing manners. This paper also presents supplementary research on the effects of source-drain spacing (L_ds) and gate width (W_g) on switching performance. This research achieves a dynamic balancing method for structural parameters, delivering application-specific design rules for different scenarios ranging from high-frequency to high-power applications. Full article

Ozone (O₃) is a reactive oxidant increasingly applied in biomedical settings, yet its dose-dependent effects on innate immune cells, particularly those from non-human species, remain insufficiently defined. Within a One Health framework, this study examined how two clinically relevant O₃ exposure regimens (30 µg/mL and 90 µg/mL) affect porcine neutrophils and monocytes isolated from peripheral blood. Cell viability, reactive oxygen and nitrogen species (RONS) production, and the activity of key enzymes (myeloperoxidase, elastase, alkaline phosphatase, arginase) were assessed at 1 h and 24 h post-exposure. The lower dose induced mild functional activation without compromising viability, whereas the higher dose triggered pronounced oxidative stress, enhanced degranulation, and reduced neutrophil viability by more than 60%. Neutrophils exhibited a stronger and more dynamic response than monocytes, which retained viability and differentiation capacity at 30 µg/mL but showed impaired function at 90 µg/mL. These findings highlight the dual nature of O₃, where controlled exposure may support immunomodulation, while excessive dosing disrupts cell function. Defining safe and effective therapeutic windows remains critical for future applications. Full article

This paper presents the electrical characterization of the on-resistance (R_ON) of on-wafer 100 V p-GaN power High-Electron-Mobility Transistors (HEMTs). This study assesses device degradation in the context of a monolithically integrated half-bridge circuit, considering both Low-Side (LS) and High-Side (HS) configurations. Since on-wafer samples have been characterized, a custom experimental setup was developed to emulate stress conditions experienced by the devices in the half-bridge circuit. A periodic signal (T = 10 µs, T_ON = 2 µs) switching from the OFF to the ON state was applied for a cumulative duration of 1000 s. Different OFF-state stress conditions were applied by varying the gate-source OFF voltage (V_GS,OFF) between 0 V and −10 V. The on-resistance exhibited a positive drift over time for devices in either the LS or the HS configuration, with the latter showing a more pronounced degradation. Measurements at higher temperatures (up to 90 °C) were carried out to characterize the dynamics of the physical mechanism behind the degradation effects. We identified hole emission from C-related acceptor traps in the buffer as the main mechanism for the observed degradation, which is present in both the HS and the LS configurations. The additional degradation observed in the HS case was attributed to the back-gating effect, stemming from the non-null body-to-source voltage. Furthermore, we found that a more negative V_GS,OFF further increases R_ON degradation, likely related to the higher electric field near the gate contact, which enhances hole emission from C-related acceptor traps. Full article

Plasma-activated water (PAW) is a liquid enriched with reactive oxygen and nitrogen species (RONS), which impart antimicrobial and bioactive properties. In this study, PAW generated in liquid or gas phase under nitrogen or oxygen atmospheres was characterized in terms of pH, electrical conductivity, oxidation-reduction potential, surface tension, and concentrations of H₂O₂ and NO₂⁻. Hydroxyl radical (•OH) formation was confirmed using DIPPMPO as a spin-trapping probe, while antioxidant activity was determined directly in treated water for the first time. The stability of reactive species was assessed over three months at room temperature, 4 °C, and −18 °C. Results indicate that plasma effects on physicochemical parameters depend strongly on the process gas. From a long-term storage perspective, samples maintained at 4 °C stabilized at higher H₂O₂ and NO₂⁻ concentrations. Antioxidant activity persisted for up to 60 days, though at low levels. EPR analysis revealed that hydroxyl radical concentration increased slightly during storage, with 60-day samples showing higher signal intensities compared to fresh PAW. Overall, the findings provide new insights into PAW composition, radical dynamics, and stability, highlighting the influence of gas atmosphere and storage conditions on its properties and supporting its potential for applications in the food, agriculture, and biomedical sectors. Full article

Mercury exposure has been linked to male infertility. Given that mercury chloride (HgCl₂) may promote an oxido-inflammatory milieu associated with pathophysiological derangements, it is hypothesised that Thymoquinone (TQ), an antioxidant and anti-inflammatory agent, may mitigate the gradual harmful effects of mercury exposure on rat testes, epididymis, and hypothalamus, as these organs are vital to reproductive function. To test this hypothesis, 40 rats (strain: Wistar; sex: male) were randomly assigned to five cohorts of eight rats each. After a 7-day acclimation, treatments were dispensed for 28 consecutive days accordingly: Cohort I: distilled water only, as control; Cohort II: HgCl₂ only (20 µg/mL); Cohort III: TQ only (2.5 mg/kg); Cohort IV: HgCl₂ + TQ (20 µg/mL + 2.5 mg/kg); and Cohort V: HgCl₂ + TQ (20 µg/mL + 5 mg/kg). Co-treatment with TQ preserved the body and organ weight of the HgCl₂ exposed animals. However, TQ did not reduce HgCl₂-induced dysfunction in sperm function and morphology. The serum follicle-stimulating hormone (FSH), luteinising hormone (LH), and testosterone were increased significantly (p < 0.05) by TQ co-treatment, while decreasing the prolactin level. TQ administration also increased (p < 0.05) testicular enzymes, including alkaline phosphatase (ALP), lactate dehydrogenase (LDH), acid phosphatase (ACP), and glucose-6-phosphate dehydrogenase (G6PD) activities, which HgCl₂ decreased. TQ administration increased (p < 0.05) HgCl₂-induced decreases in catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione (GSH), glutathione-s-transferase (GST), and total sulfhydryl group (TSH) levels in the testes, epididymis, and hypothalamus of experimental rats. Further, TQ reduced HgCl₂-mediated increases in RONS-reactive oxygen and nitrogen species; LPO–lipid peroxidation; PC–protein carbonyl formation; and XO–xanthine oxidase activity. Furthermore, levels of inflammatory biomarkers, including tumour necrosis factor alpha (TNF-α), nitric oxide (NO), interleukin-1 beta (IL-1β), and myeloperoxidase (MPO), were decreased (p < 0.05) in the co-treated groups, with a higher dose of TQ (5.0 mg/kg) showing a more pronounced protective effect. Additionally, TQ co-administration increased Bax and decreased Bcl-2 and p53 protein levels (p < 0.05), thereby protecting the rats’ testes, epididymis, and hypothalamus from HgCl₂-induced apoptosis. Molecular docking simulation analysis revealed TQ interaction dynamics with PPAR-α and PPAR-δ to suppress NF-kB-mediated pro-inflammatory sequela as well as activate Nrf-2-mediated antioxidant defence system. These predicted biological effects of TQ resonate with the findings from the in vivo studies. Therefore, supplementation with TQ may help reduce chemical-induced toxicities, including HgCl₂‘s reproductive toxicity. Full article

In this paper, the impact of SiN passivation on dynamic-R_ON degradation of AlGaN/GaN HEMTs devices is put in evidence. To this end, samples showing different SiN passivation stoichiometry are considered, labeled as Sample A and Sample B. For dynamic-R_ON tests, two different experimental setups are employed to investigate the R_ON-drift showing up during conventional switch mode operation by driving the DUTs under both (i) resistive load and (ii) soft-switching trajectory. This allows to discern the impact of hot carriers and off-state drain voltage stress on the R_ON parameter drift. Measurements performed with both switching loci shows similar dynamic-R_ON response, indicating that hot carriers are not involved in the degradation of tested devices. Nevertheless, a significant difference was observed between Sample A and Sample B, with the former showing an additional R_ON-degradation mechanism, not present on the latter. This additional drift is totally ascribed to the SiN passivation layer and is confirmed by the different leakage current measured across the two SiN types. The mechanism is explained by the injection of negative charges from the Source Field-Plate towards the AlGaN surface that are captured by surface/dielectric states and partially depletes the 2DEG underneath. Full article

Dynamic on-resistance (R_ON) of commercial GaN on Si normally off high-electron-mobility transistor (HEMT) devices is a very important parameter because it is responsible for conduction losses that limit the power conversion efficiency of high-power switching converters. Due to charge trapping effects, dynamic R_ON is always higher than in DC, a behavior known as current collapse. To study how short-time dynamics of charge trapping and release affects R_ON we use rectangular 0–5 V gate voltage pulses with durations in the 1 μs to 100 μs range. Measurements are first carried out for single pulses of increasing duration, and it is found that R_ON depends on both pulse duration and drain current I_D, being higher at shorter pulse durations and lower I_D. For a train of five pulses, R_ON decreases with pulse number, reaching a steady state after a time interval of 100 μs. The response to a five pulses train is compared to that of a square-wave signal to study the time evolution of R_ON toward a dynamic steady state. The DC R_ON is also measured, and it is a factor of ten smaller than dynamic R_ON at the same I_D. This confirms that a reduction in trapped charges takes place in DC as compared to the square-wave switching operation. Additional off-state stress tests at V_DS = 55 V reveal the presence of residual surface traps in the drain access region, leading to four times increase in R_ON in comparison to pristine devices. Finally, the dynamic R_ON is also measured by the double-pulse test (DPT) technique with inductive load, giving a good agreement with results from single-pulse measurements. Full article

Charge carrier traps due to crystal defects in GaN on Si HEMT devices are responsible for dynamic performance degradation, long-term reliability limitations, and peculiar failure modes. The behavior of traps depends on many variables including heterostructure quality, the specific device structure, and operating conditions. To study the short time dynamics of charge trapping and release on the threshold voltage shift and hysteresis of commercial normally off GaN HEMTs we use triangular 0–5 V gate voltage pulses in the μs to ms duration range. Measurements are performed for single pulses by varying pulse duration and for a train of a few pulses by varying their number. The results indicate that hysteresis and related threshold voltage shift occur after repeated pulses, suggesting an accumulation of trapped charges. However, for a triangular wave hysteresis vanishes, meaning that a dynamic balance between charge trapping and release is established in the device. This can be considered as a positive indicator of device robustness and reliability. The same method, used to measure the gate threshold voltage shift and dynamic R_ON after a 30 min off-state DC stress at V_DS = 55 V with a floating gate, highlights an appreciable performance degradation of the device. Full article

The explosive demand for high-performance secondary power sources in artificial intelligence (AI) has brought significant opportunities for low-voltage GaN devices. This paper focuses on research on high-efficiency and high-reliability low-voltage p-GaN gate HEMTs with a gate–drain distance, L_GD, of 1 to 3 μm in our pilot line, manufactured on 6-inch Si using a CMOS-compatible process, with extraordinary wafer-level uniformity. Specifically, these fabricated p-GaN gate HEMTs with an L_GD of 1.5 μm demonstrate a blocking voltage of over 180 V and a high V_TH of 1.6 V and exhibit a low R_ON of 2.8 Ω·mm. It is found that device structure optimization can significantly enhance device reliability. That is, through the dedicated optimization of source field plate structure and interlayer dielectric (ILD) thickness, the dynamic ON-resistance, R_ON, degradation of devices with an L_GD of 1.5 µm was successfully suppressed from 60% to 20%, and the V_TH shift was significantly reduced from 1.1 to 0.5 V. Further, the devices also passed preliminary gate bias stress and high-voltage OFF-state stress tests, providing guidance for preparing high-performance, low-voltage p-GaN gate HEMTs in the future. Full article

The immune microenvironment plays a critical role in tumor growth and development. Immune activation within the tumor microenvironment is dynamic and can be modulated by tumor intrinsic and extrinsic signaling. The RON receptor tyrosine kinase is canonically associated with growth signaling and wound healing, and this receptor is frequently overexpressed in a variety of cancers. Epithelial cells, macrophages, dendritic cells, and fibroblasts express RON, presenting an important axis by which RON overexpressing tumors influence the tumor microenvironment. This review synthesizes the existing literature on the roles of tumor cell-intrinsic and -extrinsic RON signaling, highlighting areas of interest and gaps in knowledge that show potential for future studies. Full article

Financial stability analysis requires volatility modeling, especially in emerging nations where pension fund systems are very vulnerable to macrofinancial risks. In order to examine the volatility dynamics of Romania’s private pension system, this study uses daily net asset value (NAV) data from 2012 to 2024 to evaluate four GARCH-type models: standard GARCH (sGARCH), exponential GARCH (EGARCH), Glosten–Jagannathan–Runkle GARCH (GJR-GARCH), and component GARCH (C-GARCH). The analysis includes domestic and international equity indices (BET, STOXX), government bond yields (ROMGB 10Y, ROMANI 5Y), short-term interbank rates (ROBOR ON), and exchange rate fluctuations (RON/EUR). Current findings indicate that EGARCH captures asymmetric fluctuations in pension fund performance, where positive shocks generate larger increases in volatility than negative ones, highlighting an atypical asymmetry pattern. Furthermore, the stabilizing effects of government bonds are overshadowed by stock market behavior, which becomes the primary driver of risk. Fluctuations in exchange rates further increase volatility, especially in markets vulnerable to external disturbances. The findings offer empirical evidence for the necessity of more cautious risk management approaches and highlight the importance of regulatory oversight in maintaining market confidence. The study underscores the importance of customized allocation frameworks that reduce vulnerability to disruptive events while maintaining prospects for sustained growth. This new dataset contributes to enhancing the comprehension of pension fund volatility within the context of emerging markets. These insights can assist managers and policymakers seeking to fortify retirement outcomes. Full article

Background/Objectives: Globally, healthcare systems face challenges in optimizing performance, particularly in the wake of the COVID-19 pandemic. This study focuses on the analysis and forecasting of key performance indicators (KPIs) for the County Emergency Clinical Hospital in Craiova, Romania. The study evaluates indicators such as average length of stay (ALoS), bed occupancy rate (BOR), number of cases (NC), case mix index (CMI), and average cost per hospitalization (ACH), providing insight into their dynamics and future trends. Methods: We performed statistical analyses on quarterly data from 2010 to 2023, employing descriptive statistics and stationarity tests (e.g., Dickey–Fuller), using ARIMA models to forecast each KPI, ensuring model validation through tests for autocorrelation, heteroscedasticity, and stationarity. The model selection prioritized Akaike and Schwarz criteria for robustness. Results: The findings reveal that ALoS and BOR demonstrate seasonality and are influenced by colder months, and it is expected that the ALoS will stabilize to around five days by 2025. Moreover, we predict that the BOR will range between 46 and 52%, reflecting these seasonal variations. The NC forecasts indicate a post-pandemic recovery but to below pre-pandemic levels, and we project the CMI to stabilize at around 1.54, suggesting a return to consistent case complexity. The ACH showed significant growth, particularly in the fourth quarter, driven by inflation and seasonal costs, and it is projected to reach more than RON 3000 by 2025. Conclusions: This study highlights the utility of ARIMA models in forecasting healthcare KPIs, enabling proactive resource planning and decision-making. The findings underscore the impact of seasonality and economic factors on hospital operations, offering valuable insights for improving efficiency and adapting to post-pandemic challenges. Full article

The SiC MOSFET with an integrated SBD (SBD-MOSFET) exhibits excellent performance in power electronics. However, the static and dynamic characteristics of this device are influenced by a multitude of parameters, and traditional TCAD simulation methods are often characterized by their complexity. Due to the increasing research on neural networks in recent years, such as the application of neural networks to the prediction of GaN JBS and Finfet devices, this paper considers the application of neural networks to the performance prediction of SiC MOSFET devices with an integrated SBD. This study introduces a novel approach utilizing neural network machine learning to predict the static and dynamic characteristics of the SBD-MOSFET. In this research, SBD-MOSFET devices are modeled and simulated using Sentaurus TCAD(2017) software, resulting in the generation of 625 sets of device structure and sample data, which serve as the sample set for the neural network. These input variables are then fed into the neural network for prediction. The findings indicate that the mean square error (MSE) values for the threshold voltage (Vth), breakdown voltage (BV), specific on-resistance (R_on), and total switching power dissipation (E) are 0.0051, 0.0031, 0.0065, and 0.0220, respectively, demonstrating a high degree of accuracy in the predicted values. Meanwhile, in the comparison of convolutional neural networks and machine learning, the CNN accuracy is much higher than the machine learning methods. This method of predicting device performance via neural networks offers a rapid means of designing SBD-MOSFETs with specified performance targets, thereby presenting significant advantages in accelerating research on SBD-MOSFET performance prediction. Full article

Radiation liver injury is a common complication of hepatocellular carcinoma radiotherapy. It is mainly caused by irreversible damage to the DNA of hepatocellular cells directly by radiation, which seriously interferes with metabolism and causes cell death. AdipoRon can maintain lipid metabolism and stabilize blood sugar by activating adiponectin receptor 1 (AdipoR1). However, the role of AdipoRon/AdipoR1 in the regulation of ionizing radiation (IR)-induced mitochondrial damage remains unclear. In this study, we aimed to elucidate the roles of AdipoRon/AdipoR1 in IR-induced mitochondrial damage in normal hepatocyte cells. We found that AdipoRon treatment rescued IR-induced liver damage in mice and mitochondrial damage in normal hepatocytes in vivo and in vitro. AdipoR1 deficiency exacerbated IR-induced oxidative stress, mitochondrial dynamics, and biogenesis disorder. Mechanistically, the absence of AdipoR1 inhibits the activity of adenosine monophosphate-activated protein kinase α (AMPKα), subsequently leading to disrupted mitochondrial dynamics by decreasing mitofusin (MFN) and increasing dynamin-related protein 1 (DRP1) protein expression. It also controls mitochondrial biogenesis by suppressing the peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC1α) and transcription factor A (TFAM) signaling pathway, ultimately resulting in impaired mitochondrial function. To sum up, AdipoRon/AdipoR1 maintain mitochondrial function by regulating mitochondrial dynamics and biogenesis through the AdipoR1-AMPKα signaling pathway. This study reveals the significant role of AdipoR1 in regulating IR-induced mitochondrial damage in hepatocytes and offers a novel approach to protecting against damage caused by IR. Full article