Biomarkers of oxidative stress and protein–protein interaction in chronic obstructive pulmonary disease

<p><b>Content:</b> The increased oxidative stress in chronic obstructive pulmonary disease (COPD) patients is the result of increased inhaled oxidants, generated by various cells of the airways.</p> <p><b>Objective:</b> The investigation included measurements of malondiadehyde (MDA), uric acid, ascorbic acid, and matrix metalloproteinase-12 (MMP-12) in COPD patient. We also performed genetic analysis for protein–protein interaction (PPI) network.</p> <p><b>Materials and methods:</b> The study was conducted on healthy subjects with normal lung function (NS, 14 subjects) and 28 patients (Global Initiative for Chronic Obstructive Lung Disease (Gold) 1 and Gold 2) with COPD.</p> <p><b>Results:</b> There was significant (<i>p</i> < .001) increase in MMP-12, MDA and uric acid levels as compared to healthy controls. A significant (<i>p</i> < .001) decline in ascorbic acid level was observed in COPD patients. The PPI was found to be 0.833 which indicated that proteins present in COPD are linked.</p> <p><b>Discussion and conclusion:</b> This study suggests oxidative stress plays an important role in COPD and the PPI provide indication that proteins present in COPD are linked.</p

Adaptive Multi-Agent System and Mixed Integer Linear Programming Optimization Comparison for Grid Stability and Commitment Mismatch in Smart Grids

International audienceExisting electrical networks are going through a transition and distributed energy resource, if not managed properly, can hinder this transition. Uncontrolled introduction of photovoltaics and electric vehicles in distribution networks would lead to substantial issues such as commitment mismatches, line congestions, voltage deviations, etc. This paper presents the use of a classical approach, mixed integer linear programming optimization, and a novel approach, adaptive multi-agent system, to solve the highlighted distribution side challenges by utilizing electric vehicles' storage capacity. This comparison serves as a great tool to benchmark the performance of the under-development adaptive multi-agent system methodology

Influence of Fluorine implantation on the electrical characteristics of GaN-on-GaN vertical Schottky and P-N diodes

International audienceGaN-based power devices have been gaining popularity in recent years thanks to GaN properties such as wide bandgap, high electron mobility, and high breakdown field strength, allowing low Ron, and high-frequency operation. Lateral GaN devices, which are grown on a foreign substrate like Si and sapphire [1], have already been commercialized and have been able to achieve much better performance compared to their silicon counterparts. However, these devices are unable to achieve sufficiently high breakdown voltage (BV>1kV). One alternative to boost the breakdown voltage and lower Ron is to have vertical devices grown on a native GaN substrate. These devices still suffers from premature breakdown and high reverse leakage due to electric field crowding at the junction edge. This issue can be resolved by creating an effective edge termination either by using Mg implantation [2] to create a p-doped region or by alternate species implantation by Nitrogen [3] or Argon [4] to create a resistive region at the junction edge. However, due to the difficulty in creating p-GaN by ion implantation due to compensation by Hydrogen and large activation energy of ~170 meV, alternate species of implantation is preferred. Fluorine ion implantation [5] is an attractive alternative as it can form a negative fixed charge owning to its highest electronegativity thus spread the electric field away from the contact and can also modulate the free charge carrier in GaN.In this study, P-N and Schottky structures are fabricated using multi energy Fluorine implantation as an edge termination. The influence of the implant on the electrical characteristics is studied by varying the implant overlap beneath the contact. µ-Raman scanning of the device suggests a reduction in free charge concentration in the implanted region, and an increase in the built-in potential obtained through C-V measurements compared to the device with no implantation. The influence of implantation on the electrical characteristics (B-V, I-V, and C-V) is analyzed and TCAD simulations using Synopsys® SentaurusTM are performed to help interpret the results

Influence of Fluorine implantation on the electrical characteristics of GaN-on-GaN vertical Schottky and P-N diodes

International audienceGaN-based power devices have been gaining popularity in recent years thanks to GaN properties such as wide bandgap, high electron mobility, and high breakdown field strength, allowing low Ron, and high-frequency operation. Lateral GaN devices, which are grown on a foreign substrate like Si and sapphire [1], have already been commercialized and have been able to achieve much better performance compared to their silicon counterparts. However, these devices are unable to achieve sufficiently high breakdown voltage (BV>1kV). One alternative to boost the breakdown voltage and lower Ron is to have vertical devices grown on a native GaN substrate. These devices still suffers from premature breakdown and high reverse leakage due to electric field crowding at the junction edge. This issue can be resolved by creating an effective edge termination either by using Mg implantation [2] to create a p-doped region or by alternate species implantation by Nitrogen [3] or Argon [4] to create a resistive region at the junction edge. However, due to the difficulty in creating p-GaN by ion implantation due to compensation by Hydrogen and large activation energy of ~170 meV, alternate species of implantation is preferred. Fluorine ion implantation [5] is an attractive alternative as it can form a negative fixed charge owning to its highest electronegativity thus spread the electric field away from the contact and can also modulate the free charge carrier in GaN.In this study, P-N and Schottky structures are fabricated using multi energy Fluorine implantation as an edge termination. The influence of the implant on the electrical characteristics is studied by varying the implant overlap beneath the contact. µ-Raman scanning of the device suggests a reduction in free charge concentration in the implanted region, and an increase in the built-in potential obtained through C-V measurements compared to the device with no implantation. The influence of implantation on the electrical characteristics (B-V, I-V, and C-V) is analyzed and TCAD simulations using Synopsys® SentaurusTM are performed to help interpret the results

Electrical Transport Characteristics of Vertical GaN Schottky-Barrier Diode in Reverse Bias and Its Numerical Simulation

We investigated the temperature-dependent reverse characteristics (JR-VR-T) of vertical GaN Schottky-barrier diodes with and without a fluorine-implanted edge termination (ET). To understand the device leakage mechanism, temperature-dependent characterizations were performed, and the observed reverse current was modeled through technology computer-aided design. Different levels of current were observed in both forward and reverse biases for the ET and non-ET devices, which suggested a change in the conduction mechanism for the observed leakages. The measured JR-VR-T characteristics of the non-edge-terminated device were successfully fitted in the entire temperature range with the phonon-assisted tunneling model, whereas for the edge-terminated device, the reverse characteristics were modeled by taking into account the emission of trapped electrons at a high temperature and field caused by Poole–Frenkel emission

Influence of fluorine implantation on the physical and electrical characteristics of GaN-on-GaN vertical Schottky diode

International audienc

Electrical Behavior of Vertical Pt/Au Schottky Diodes on GaN Homoepitaxy

International audienceSchottky barrier diodes on GaN on GaN substrates are fabricated for the purposeof material and technology characterization. The epitaxial layers are grown byMOCVD. I–V measurements as a function of the temperature in the range80–480 K show ideality factor (n) and barrier height (ϕB) variations not following athermionic (TE) model. Consequently, barrier height fluctuations are considered.In the temperature range 280–480 K, an average barrier height of 1.31 eV with arelatively large standard deviation (σ) of 0.15 eV is extracted using this model. Then(T ) variation is also analyzed in order to extract the field sensibility of 1) themean barrier height variation (ρ2 = -0.1) and 2) the barrier height standarddeviation (ρ3 = -15mV). The corrected Richardson plot usingϕB and σ values islinear and gives a Richardson constant of 31.5 A cm² K² close to the theoreticalvalue of 26.4 A cm² K². For a deeper understanding of ϕB fluctuation origins,micro-Raman mapping of the epitaxial layers and deep-level transient spectroscopy(DLTS) are used. μ-RS mappings show compressive strain for diodeshaving suffered electrical breakdown. DLTS analysis shows the presence of ninelevels whose signatures are extracted and nature discussed

Micro-Raman characterization of vertical GaN Schottky and PN diodes

In this work, measurements from Cathodo-Luminescence (CL), micro-Raman spectroscopy and Breakdown Voltage (BV) have been coupled to assess the effects of physical parameters such as threading dislocations and effective doping level homogeneity on the electrical performances of vertical GaN Schottky and PN diodes. Two different substrates from Saint Gobain Lumilog and Sumitomo Electric with different threading dislocation densities have been compared