Search results for "n-type"
showing 10 items of 66 documents
Suppression of leakage currents in GaN-based LEDs induced by reactive-ion etching damages
2008
Forward and reverse leakage currents in GaN/InGaN multi-quantum well light-emitting diodes (LEDs) are caused by reactive-ion etching (RIE) damages during device patterning. A method to recover the damaged surfaces, based on a chemical etch in KOH: ethylene-glycol is described. Leakage currents decrease of more than a factor of 10 and are completely suppressed in most of devices.
Anxiety and the severity of Tension-Type Headache mediate the relation between headache presenteeism and workers’ productivity
2018
The primary objective of this study was to explore the mechanisms and conditions whereby Tension-Type Headache (TTH) presenteeism relates to health-related loss of productivity as a result of both reduced physical and mental health. To this end, Structural Equation Modeling (SEM) was used to conduct a secondary data analysis of a randomized clinical trial involving 78 Tension-type Headache (TTH) patients. The results showed that TTH presenteeism did not directly relate to health-related loss of productivity, either due to physical, or mental health problems. However, through anxiety-state, TTH presenteeism decreased patients' productivity, as consequence of reduced physical and mental healt…
Migraine without aura as a possible sign of covert neurological involvement in Behçet's disease: A case-control study
2004
In the present study we evaluate the prevalence of headache and the frequency of different primary headaches in patients with Bebçet's Disease (BD) without neurological involvement. Furthermore, we investigate the relationship between headache with other clinical, and behavioural variables. Twenty-seven BD patients and 27 control subjects underwent a validated semi-structured questionnaire based on the International Headache Society criteria. Levels of anxiety and depression, disease activity, and current medication were collected. Headache occurred in about 90% of BD patients. There was no difference in the prevalence of the different headache syndromes between BD patients and controls. O…
Positive solutions for parametric singular Dirichlet (p,q)-equations
2020
We consider a nonlinear elliptic Dirichlet problem driven by the (p,q)-Laplacian and a reaction consisting of a parametric singular term plus a Caratheodory perturbation f(z,x) which is (p-1)-linear as x goes to + infinity. First we prove a bifurcation-type theorem describing in an exact way the changes in the set of positive solutions as the parameter lambda>0 moves. Subsequently, we focus on the solution multifunction and prove its continuity properties. Finally we prove the existence of a smallest (minimal) solution u*_lambda and investigate the monotonicity and continuity properties of the map lambda --> u*_lambda.
First principles modeling of 3d-metal doped three-layer fluorite-structured TiO2 (4,4) nanotube to be used for photocatalytic hydrogen production
2017
This study has been supported by the EC ERA.Net RUS Plus project No. 237 WATERSPLIT, Russian Basic Research Foundation No. 16-53-76019, and additionally by the IMIS2 Program (Latvia). The authors are also indebted to R. A. Evarestov and O. Lisovski for stimulating discussions as well as to A. Chesnokov for technical assistance.
New-onset headache following COVID-19: An Italian multicentre case series
2023
Objective: To describe the characteristics of patients with new-onset headache following SARS-CoV-2 infection. Background: SARS-CoV-2 infection leads to several neurological manifestations, and headache is a frequent and disabling symptom, both exacerbating pre-existing headache syndromes and causing new-onset ones. Methods: Patients with new-onset headache after SARS-CoV-2 infection with consent to participate were included, while those ones with previous headaches were excluded. The temporal latency of headache after infection, pain characteristics, and concomitant symptoms were analysed. Moreover, the efficacy of acute and preventive medications was explored. Results: Eleven females (med…
Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand
2013
Ethylene/1-olefin copolymerization using vanadium and titanium complexes bearing tetradentate [O,N,N,O]-type ligand and EtAlCl2 or MAO as a cocatalyst is carried out. In the presence of the vanadium complex activated with EtAlCl2 is observed (a) negative “comonomer effect”, (b) high comonomer incorporation and narrow chemical composition distribution (CCD), (c) unexpected copolymer microstructure, and (d) increased molecular weight of copolymers when compared with the homopolymer. In contrast, titanium catalyst gives copolymers with lower 1-olefin content and broad CCD. Supported complexes show higher activity, lower 1-olefins incorporation and give copolymers with ultra high molecular weig…
Capsaicin differentially modulates voltage-activated calcium channel currents in dorsal root ganglion neurones of rats
2005
It is discussed whether capsaicin, an agonist of the pain mediating TRPV1 receptor, decreases or increases voltage-activated calcium channel (VACC) currents (ICa(V)). ICa(V) were isolated in cultured dorsal root ganglion (DRG) neurones of rats using the whole cell patch clamp method and Ba 2+ as charge carrier. In large diameter neurones (>35Am), a concentration of 50AM was needed to reduce ICa(V) (activated by depolarizations to 0 mV) by 80%, while in small diameter neurones (30Am), the IC50 was 0.36 AM. This effect was concentration dependent with a threshold below 0.025 AM and maximal blockade (>80%) at 5AM. The current–voltage relation was shifted to the hyperpolarized direction with an…
Parametric nonlinear singular Dirichlet problems
2019
Abstract We consider a nonlinear parametric Dirichlet problem driven by the p -Laplacian and a reaction which exhibits the competing effects of a singular term and of a resonant perturbation. Using variational methods together with suitable truncation and comparison techniques, we prove a bifurcation-type theorem describing the dependence on the parameter of the set of positive solutions.
Experimental and theoretical study on the optical properties of LaVO4 crystals under pressure
2018
We report optical absorption and luminescence measurements in pure and trivalent neodymium (Nd3+) doped LaVO4 crystals up to 25 GPa. Nd3+ luminescence has been employed as a tool to follow the structural changes in the crystal. We also present band-structure and crystal-field calculations that provide the theoretical framework to accurately explain the observed experimental results. In particular, both optical absorption and luminescence measurements evidence that a phase transition takes place close to 12 GPa. They also provide information on the pressure dependence of the band-gap as well as the emission lines under compression. We found drastic changes in the optical properties of LaVO4 …