Abstract In this study, a thin barrier AlGaN/GaN heterojunction diode with a NiO anode is proposed. NiO as an anode combined with a 5 nm AlGaN barrier layer can significantly deplete two-dimensional electron gas in the anode region of the device. Combined with the etching-free technology, the damage caused by etching the AlGaN barrier layer is successfully avoided. The capacitance of the device was reduced from 28 pF mm −1 (Schottky) to 966 fF/mm (NiO) which reduced 97%. At the same time the NiO anode devices with a reverse current leakage of ~10 −8 A/mm@−100V achieved a high current ON/OFF ratio of ~10 -8 . NiO not only reduces the capacitance and leakage of the device but also enhances its anti-collapse ability. Without using the structure of field plates, the breakdown voltage of the device was also increased compared with the Schottky diode.
This study is to observe the effects of sequoyitol on the expression of NADPH oxidase subunits p22 phox and p47 phox in rats with type 2 diabetic liver diseases. The model of high fat and high sugar diet as well as intraperitoneal injection of small dose of streptozotocin (STZ, 35 mg x kg(-1)) induced diabetic rat liver disease was used. After sequoyitol (50, 25 and 12.5 mg x kg(-1)) was administrated for 6 weeks, the contents of blood glucose (BG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total antioxidant capacity (T-AOC), hydrogen peroxide (H2O2), NO and insulin (Ins) were measured, liver p22 phox and p47 phox mRNA content was determined with real-time PCR and the expression of p22 phox and p47 phox protein was examined by Western blotting. In addition, pathological changes in liver were observed with HE staining. Sequoyitol could reduce the content of fasting blood glucose, ALT, AST, Ins and H2O2, restore insulin sensitive index (ISI) and weight, elevate liver tissue T-AOC and NO content, reduce the NADPH oxidase subunit liver tissue p22 phox and p47 phox mRNA and protein expression, as well as ameliorate liver pathologic lesions. The results showed that sequoyitol can ease the type 2 diabetic rat liver oxidative stress by lowering NADPH oxidase expression.
Connexin 43 (Cx43) is a critical gene for maintaining myocardial homeostasis. Interestingly, Cx43 and stress-induced phosphoprotein 1 (STIP1) were recorded to be lowly expressed in ischemia/reperfusion (I/R). However, their impacts on reperfusion arrhythmia (RA) remain to be explored. Our study aimed to find out the related underlying mechanisms.After the establishment of an isolated heart model through Langendorff perfusion, the heart rate, conduction activation time, conduction velocity, and conduction direction of the left ventricle were evaluated, along with the apoptotic rate detection in the collected myocardial tissues. After the construction of a hypoxia/reoxygenation (H/R)-induced cellular model, cell apoptosis, intercellular communication, cell viability, and the content of reactive oxygen species, superoxide dismutase, malondialdehyde, and lactic dehydrogenase were measured. The expression of Cx43 and STIP1 was determined in both rat heart and cell models. The bindings of STIP3 and Cx43 to heat shock protein 90 (HSP90) and heat shock protein 70 (HSP70) were verified.Relative to the corresponding controls, Cx43 and STIP1 were decreased in myocardial tissues of RA rats and H/R-stimulated H9C2 cells, where Cx43-binding HSP70 and HSP90 were respectively increased and decreased, and ubiquitination level of Cx43 was enhanced. STIP1 overexpression promoted protein expression of Cx43, intercellular communication, and cell viability, and reduced cell apoptosis and oxidative stress in H/R-stimulated H9C2 cells.STIP1 promoted Cx43 expression to improve intercellular communication and reduce oxidative stress in H/R-stimulated H9C2 cells.
Public transit is immensely important among recent immigrants for enabling daily travel and activity participation. The objectives of this study are to examine whether immigrants settle in areas of high or low transit accessibility and how this affects transit mode share. This is analyzed via a novel comparison of two gateway cities: Sydney, Australia and Toronto, Canada. We find that in both cities, recent immigrants have greater levels of public transit accessibility to jobs, on average, than the overall population, but the geography of immigrant settlement is more suburbanized and less clustered around commuter rail in Toronto than in Sydney. Using logistic regression models with spatial filters, we find significant positive relationships between immigrant settlement patterns and transit mode share for commuting trips, after controlling for transit accessibility and other socio-economic factors, indicating an increased reliance on public transit by recent immigrants. Importantly, via a sensitivity analysis, we find that these effects are greatest in peripheral suburbs and rural areas, indicating that recent immigrants in these areas have more risks of transport-related social exclusion due to reliance on insufficient transit service.
Over a half of the diabetic individuals develop macrovascular complications that cause high mortality. Oxidative stress (OS) promotes endothelial dysfunction (ED) which is a critical early step toward diabetic macrovascular complications. Nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of cellular antioxidant defense system and combats diabetes-induced OS. Previously, we found that impaired NRF2 antioxidant signaling contributed to diabetes-induced endothelial OS and dysfunction in mice. The present study has investigated the effect of microRNA-200a (miR-200a) on NRF2 signaling and diabetic ED. In aortic endothelial cells (ECs) isolated from C57BL/6 wild-type (WT) mice, high glucose (HG) reduced miR-200a levels and increased the expression of kelch-like ECH-associated protein 1 ( Keap1 ) – a target of miR-200a and a negative regulator of NRF2. This led to the inactivation of NRF2 signaling and exacerbation of OS and inflammation. miR-200a mimic (miR-200a-M) or inhibitor modulated KEAP1/NRF2 antioxidant signaling and manipulated OS and inflammation under HG conditions. These effects were completely abolished by knockdown of Keap1 , indicating that Keap1 mRNA is a major target of miR-200a. Moreover, the protective effect of miR-200a-M was completely abrogated in aortic ECs isolated from C57BL/6 Nrf2 knockout (KO) mice, demonstrating that NRF2 is required for miR-200a’s actions. In vivo , miR-200a-M inhibited aortic Keap1 expression, activated NRF2 signaling, and attenuated hyperglycemia-induced OS, inflammation and ED in the WT, but not Nrf2 KO, mice. Therefore, the present study has uncovered miR-200a/KEAP1/NRF2 signaling that controls aortic endothelial antioxidant capacity, which protects against diabetic ED.
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