145 research outputs found

    Immunobiological properties of selected natural and chemically modified phenylpropanoids

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    Effects of natural and structurally transformed lignans compared with stilbenes or stilbenoids on production of nitric oxide (NO) triggered by lipopolysaccharide (LPS) and interferon-γ (IFN-γ), tested under in vitro conditions using murine resident peritoneal macrophages, are reviewed. Relation between the molecular structure and immunobiological activity was investigated, and implication of substituents, double bond stereochemistry, or cyclic attachments (double bond geometry fixation) was assessed. The focus was on lignans and stilbenoids because they were originally selected for a joint project of common interest to phytochemical and pharmacological investigation and because they represent well interesting and universally attractive groups of polyphenols with a feasible potential for therapeutic or nutraceutic utilization

    Trap-Assisted Tunneling in the Schottky Barrier

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    The paper presents a new way how to calculate the currents in a Schottky barrier. The novel phenomeno-logical model extends the Shockley-Read-Hall recombi-nation-generation theory of trap-assisted tunneling. The proposed approach explains the occurrence of large leakage currents in Schottky structures on wide band semi-conductors with a high Schottky barrier (above 1 eV) and with a high density of traps. Under certain conditions, trap-assisted tunneling (TAT) plays a more important role than direct tunneling

    Svojstva višeslojnih materijala ozračenih jakim neutronskim tokovima

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    Multilayer materials based on silicon were exposed to fast neutrons with fluences ranging from 1015 to 1019 n/cm2. C-V, deep level transient spectroscopy (DLTS) and I-V measurements were carried out to analyse the properties of the respective layers as well as the SiO2-(n-type)silicon and metal-(n-type)silicon interfaces. The detected divacancies and E-centres are likely the main cause of carrier reduction that has been found to depend on the initial doping concentration of the layer. This study has proven that both investigated interfaces exhibit radiation induced interface traps.Višeslojni materijali na osnovi silicija izloženi su brzim neutronima tokovima od 1015 do 1019 n/cm2 . Mjerenja C − V , prijelazna spektroskopija dubokih stanja i I − V mjerenja načinjeni su radi analize svojstava višeslojeva kao i SiO2 – (nsilicij) te metal – (n-silicij) granice. Cini se da su glavni razlog smanjenja nositelja opažene dvojne šupljine i E-centri, koji ovise o početnoj koncentraciji dodataka (dopanata) u sloju. Pokazano je da obje istraživane granice sadrže klopke uzrokovane ozračivanjem

    Composition related electrical active defect states of InGaAs and GaAsN

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    This paper discusses results of electrically active defect states - deep energy level analysis in InGaAs and GaAsN undoped semiconductor structures grown for solar cell applications. Main attention is focused on composition and growth condition dependent impurities and the investigation of their possible origins. For this purpose a widely utilized spectroscopy method, Deep Level Transient Fourier Spectroscopy, was utilized. The most significant responses of each sample labelled as InG2, InG3 and NG1, NG2 were discussed in detail and confirmed by simulations and literature data. The presence of a possible dual conduction type and dual state defect complex, dependent on the In/N composition, is reported. Beneficial characteristics of specific indium and nitrogen concentrations capable of eliminating or reducing certain point defects and dislocations are stated

    Ecdysteroid 7,9(11)-dien-6-ones as potential photoaffinity labels for ecdysteroid binding proteins

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    Three ecdysteroid 7,9(11)-dien-7-ones (dacryhainansterone, 25-hydroxydacryhainansterone and kaladasterone) were prepared by dehydration of the corresponding 11a-hydroxy ecdysteroids (ajugasterone C, turkesterone and muristerone A, respectively). The biological activities of the dienones in the Drosophila melanogaster B(II) cell bioassay, which reflect the affinity for the ecdysteroid receptor complex, showed that the dienones retain high biological activity. Irradiation at 350 nm of the ecdysteroid dienones (100 nM) with bacterially-expressed dipteran and lepidopteran ecdysteroid receptor proteins (DmEcR/DmUSP or CfEcR/CfUSP), followed by loading with [(3)H]ponasterone A revealed that irradiation of dacryhainansterone or kaladasterone resulted in blocking of >70% of the specific binding sites. Thus, ecdysteroid dienones show considerable potential as photoaffinity analogues for ecdysteroid binding proteins

    2017 User Workshop of the Copernicus Emergency Management Service – Summary Report

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    This report summarises the User Workshop of the Copernicus Emergency Management Service (EMS) – Mapping component which was held on 20-21 June 2017 at the Joint Research Centre (JRC) in Ispra, Italy. The User Workshop is the annual forum at which users, service providers, the Commission and other stakeholders exchange views and experiences of the Copernicus EMS - Mapping component. It was attended by 50 participants from across Europe, of whom eighteen were users of this service component. The focus of the User Workshop was on the two on-demand Mapping services - i.e. “Rapid Mapping” and “Risk and Recovery Mapping” - which provide geo-spatial information in support to all phases of disaster management. The information is mainly derived from satellite imagery and complemented by available ancillary data. During the first day of the Workshop, the focus was on providing insights in the technical and scientific capacity of the “Risk & Recovery” Mapping service, which delivers maps and analysis in support of disaster risk reduction, preparedness and prevention, recovery and reconstruction. The aim of this part of the Workshop was to increase awareness of this service module, which is less known than the “Rapid Mapping” service - the “24/7” (i.e. always on) service supporting emergency response operations. Users were invited to present their experience with both service modules, while a live demo of Unmanned Aerial Systems (UAS), was made, in order to show the potential of these platforms in the context of the fast provision of airborne imagery in an emergency situation. The second day of the Workshop addressed the evolution of Copernicus EMS - Mapping. Two Horizon 2020 projects were introduced and discussed: while iREACT (http://www.i-react.eu/) looks at exploiting advanced cyber technologies for disaster management, E2mC (https://www.e2mc-project.eu/) focuses on exploiting social data and crowdsourcing for use in Rapid Mapping. Other evolution-related topics addressed were links with the two Copernicus EMS Early Warning Systems (i.e. the European Flood Awareness System and the European Forest Fire Information System), product dissemination and potential new products. All topics were further discussed in groups. As every year, the discussions at the User Workshop are summarised and processed by the JRC, with a view to guiding the overall evolution of the service. The workshop agenda and presentations are available at: http://emergency.copernicus.eu/mapping/ems/copernicus-ems-mapping-user-workshop-2017JRC.E.1-Disaster Risk Managemen

    Potentiostatic Electrodeposition of Cu2O under Light and Dark for Photoelectrochemical Hydrogen Generation Applications

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    Potentiostatic electrodeposition conducted at various deposition voltages from lactate-stabilized copper sulfate electrolyte was used for preparation of Cu2O layers for Photoelectrochemical (PEC) production of hydrogen. A novel approach based on an application of light during the electrodeposition is utilized to suppress the potential drop in the Cu2O layer during the potentiostatic deposition. Structures prepared under dark and light on an Ag substrate are analyzed by X-Ray Diffraction analysis (XRD), Scanning Electron Microscopy (SEM) and Linear Sweep Voltammetry (LSV). It was shown that the application of light increases the deposition rate due to the contribution of the photogenerated carriers. The deposition voltage affects the photoresponse of light deposited structures but causes only a negligible change in dark deposited structures. The light deposited samples exhibited a higher photoresponse for all deposition voltages. The presented study suggests the light potentiostatic electrodeposition as an attractive approach for the preparation of Cu2O structures for cheap and efficient photoelectrochemical water splitting applications
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