An assessment of sputtered nitrogen-doped nickel oxide for all-oxide transparent optoelectronic applications: The case of hybrid NiO:N/TiO2 heterostructure

ransition metal oxides present a unique category of materials due to their versatile optical, electrical and mechanical properties. Nickel oxide (NiO) is an intrinsic p-type oxide semiconductor. P-NiO with controllable and reproducible physico-chemical properties, if combined with transparency and low temperature (low-T) fabrication processes, can be fully exploited in many transparent and/or flexible devices for applications, like energy management (production, manipulation, storage), sensing, wearable and health care electronics, etc. Reproducibility, transparency and low-T fabrication processes of p-type NiO are the motivation of this work. Nitrogen is one of the dopants used for modifying the properties of NiO. Until now, nitrogen-doped NiO, has shown inferior properties than those of pure NiO. In this work, we present nitrogen-doped NiO (NiO:N) thin films with enhanced properties compared to those of the undoped NiO. The NiO:N films were grown by sputtering on room-temperature substrates in plasma containing 50% Ar and 50% (O2+N2) gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, having transmittance less than 20%. Upon doping with nitrogen, the films became more transparent (around 65%), had a wide direct band gap (up to 3.67 eV) and showed clear evidence of indirect band gap, 2.50-2.72 eV, depending on %(O2-N2) in plasma. The changes in the properties of the films such as structural disorder, energy band gap, Urbach states and resistivity were correlated with the incorporation of nitrogen in their structure. The optimum NiO:N film was used to form a diode with spin-coated, mesoporous on top of a compact, TiO2 film. The hybrid NiO:N/TiO2 heterojunction was transparent showing good output characteristics, as deduced using both I-V and Cheung’s methods. The diode’s transparency and characteristics were further enhanced upon thermal treatment and this was attributed to improved NiO:N properties with annealing. Transparent NiO:N films can be realized for all-oxide flexible optoelectronic devices

Transparent all-oxide hybrid NiON/TiO2 heterostructure for optoelectronic applications

Nickel oxide (NiO) is a p-type oxide and nitrogen is one of the dopants used for modifying its properties. Until now, nitrogen-doped NiO has shown inferior optical and electrical properties than those of pure NiO. In this work, we present nitrogen-doped NiO (NiO:N) thin films with enhanced properties compared to those of the undoped NiO thin film. The NiO:N films were grown at room temperature by sputtering using a plasma containing 50% Ar and 50% (O2 + N2) gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, having a transmittance of less than 20%. Upon doping with nitrogen, the films became more transparent (around 65%), had a wide direct band gap (up to 3.67 eV) and showed clear evidence of indirect band gap, 2.50–2.72 eV, depending on %(O2-N2) in plasma. The changes in the properties of the films such as structural disorder, energy band gap, Urbach states and resistivity were correlated with the incorporation of nitrogen in their structure. The optimum NiO:N film was used to form a diode with spin-coated, mesoporous on top of a compact, TiO2 film. The hybrid NiO:N/TiO2 heterojunction was transparent showing good output characteristics, as deduced using both I-V and Cheung’s methods, which were further improved upon thermal treatment. Transparent NiO:N films can be realized for all-oxide flexible optoelectronic devices

Effect of the Novel Influenza A (H1N1) Virus in the Human Immune System

BACKGROUND: The pandemic by the novel H1N1 virus has created the need to study any probable effects of that infection in the immune system of the host. METHODOLOGY/PRINCIPAL FINDINGS: Blood was sampled within the first two days of the presentation of signs of infection from 10 healthy volunteers; from 18 cases of flu-like syndrome; and from 31 cases of infection by H1N1 confirmed by reverse RT-PCR. Absolute counts of subtypes of monocytes and of lymphocytes were determined after staining with monoclonal antibodies and analysis by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and stimulated with various bacterial stimuli. Concentrations of tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-18, interferon (FN)-alpha and of IFN-gamma were estimated in supernatants by an enzyme immunoassay. Infection by H1N1 was accompanied by an increase of monocytes. PBMCs of patients evoked strong cytokine production after stimulation with most of bacterial stimuli. Defective cytokine responses were shown in response to stimulation with phytohemagglutin and with heat-killed Streptococcus pneumoniae. Adaptive immune responses of H1N1-infected patients were characterized by decreases of CD4-lymphocytes and of B-lymphocytes and by increase of T-regulatory lymphocytes (Tregs). CONCLUSIONS/SIGNIFICANCE: Infection by the H1N1 virus is accompanied by a characteristic impairment of the innate immune responses characterized by defective cytokine responses to S.pneumoniae. Alterations of the adaptive immune responses are predominated by increase of Tregs. These findings signify a predisposition for pneumococcal infections after infection by H1N1 influenza

Solar-powered bus route: introducing renewable energy into a university campus transport system

We investigate the application of a solar-powered bus route to a small-scale transportation system, as such of a university campus. In particular, we explore the prospect of replacing conventional fossil fuel buses by electric buses powered by solar energy and electricity provided by the central grid. To this end, we employ GIS mapping technology to estimate the solar radiation at the university campus and, accordingly, we investigate three different scenarios for harnessing the available solar power: (1) solar panels installed on the roof of bus stop shelters, (2) solar panels installed at an unused open space in the university, and (3) solar roads, i.e. roads constructed by photovoltaic (PV) materials. For each of the three scenarios, we investigate the optimal technical configuration, the resulting energy generation, as well as the capital cost for application in the case of NTUA campus in Athens (Greece). The preliminary feasibility analysis showcases that all three scenarios contribute to satisfying transportation demand, proportionately to their size, with scenario (2) presenting the lowest capital cost in relation to energy generation. Therefore, we further explore this scenario by simulating its daily operation including the actions of buying and selling energy to the central grid, when there is energy deficit or surplus, respectively. A sensitivity analysis is carried out in order to ascertain the optimal size of the solar panel installation in relation to profit and reliability. Overall, results indicate that, albeit the high capital costs, solar-powered transportation schemes present a viable alternative for replacing conventional buses at the studied location, especially considering conventional PV panels. We note that present results heavily depend on the choice of capacity factors of PV materials, which differ among technologies. Yet, as capacity factors of PV panels are currently increasing, the studied schemes might be more promising in the future.ISSN:1680-7340ISSN:1680-735

Effect of clarithromycin in patients with suspected Gram-negative sepsis: results of a randomized controlled trial

A previous randomized study showed that clarithromycin decreases the risk of death due to ventilator-associated pneumonia and shortens the time until infection resolution. The efficacy of clarithromycin was tested in a larger population with sepsis. Six hundred patients with systemic inflammatory response syndrome due to acute pyelonephritis, acute intra-abdominal infections or primary Gram-negative bacteraemia were enrolled in a double-blind, randomized, multicentre trial. Clarithromycin (1 g) was administered intravenously once daily for 4 days consecutively in 302 patients; another 298 patients were treated with placebo. Mortality was the primary outcome; resolution of infection and hospitalization costs were the secondary outcomes. The groups were well matched for demographics, disease severity, microbiology and appropriateness of the administered antimicrobials. Overall 28 day mortality was 17.1 (51 deaths) in the placebo arm and 18.5 (56 deaths) in the clarithromycin arm (P0.671). Nineteen out of 26 placebo-treated patients with septic shock and multiple organ dysfunctions died (73.1) compared with 15 out of 28 clarithromycin-treated patients (53.6, P0.020). The median time until resolution of infection was 5 days in both arms. In the subgroup with severe sepsis/shock, this was 10 days in the placebo arm and 6 days in the clarithromycin arm (P0.037). The cost of hospitalization was lower after treatment with clarithromycin (P0.044). Serious adverse events were observed in 1.3 and 0.7 of placebo- and clarithromycin-treated patients, respectively (P0.502). Intravenous clarithromycin did not affect overall mortality; however, administration shortened the time to resolution of infection and decreased the hospitalization costs

Production of interleukin-1beta (IL-1β).

<p>Peripheral blood mononuclear cells of 10 healthy volunteers, of 18 patients with flu-like syndrome and of 31 patients infected by the H1N1 virus were stimulated with endotoxins (LPS), phytohemagglutin (PHA), and heat-killed isolates of <i>Candida albicans</i>, of <i>Pseudomonas aeruginosa</i>, of methicillin-resistant <i>Staphylococcus aureus</i> producing Panton-Valentine leukocidin (MRSA-PVL) and of penicillin-susceptible <i>Streptococcus pneumoniae</i>.</p

Production of tumour necrosis factor-alpha (TNFα).

<p>Peripheral blood mononuclear cells of 10 healthy volunteers, of 18 patients with flu-like syndrome and of 31 patients infected by the H1N1 virus were stimulated with endotoxins (LPS), phytohemagglutin (PHA), and heat-killed isolates of <i>Candida albicans</i>, of <i>Pseudomonas aeruginosa</i>, of methicillin-resistant <i>Staphylococcus aureus</i> producing Panton-Valentine leukocidin (MRSA-PVL) and of penicillin-susceptible <i>Streptococcus pneumoniae</i>. Superscript “a” denotes statistically significant differences compared with healthy volunteers; superscript “b” denotes statistically significant differences compared with patients with flu-like syndrome.</p

Absolute counts of T-regulatory cells of patients infected with the H1N1 virus.

<p>Results are given separately for 25 patients without pneumonia and for six patients with pneumonia (p<0.0001).</p