Search results for " Ultraviolet"
showing 10 items of 337 documents
Modelling of expected B, C, N and O Lyman-α line intensities emitted from W7-X plasmas and measured by means of the W7-X light impurity monitor system
2021
AbstractThe “C/O Monitor” for Wendelstein 7-X (W7-X) is a dedicated light impurity XUV spectrometer intended to measure Lyman-α transitions of hydrogen-like ions of four low-Z impurities—boron (4.9 nm), carbon (3.4 nm), nitrogen (2.5 nm) and oxygen (1.9 nm). Since the discussed diagnostic will deliver continuous information about the line intensities, it is crucial to understand the origin of the obtained signals with respect to the experimental plasma conditions (electron temperature and density). This, however, might be difficult because of the broad acceptance angle of the spectrometer and irregular shape of the plasma edge or SOL where the radiation is expected to mostly come from, depe…
Suppression of the vacuum space-charge effect in fs-photoemission by a retarding electrostatic front lens
2021
Review of scientific instruments 92(5), 053703 (2021). doi:10.1063/5.0046567
Characterisation of the magmatic signature in gas emissions from Turrialba Volcano, Costa Rica
2014
The equilibrium composition of volcanic gases with their magma is often overprinted by interaction with a shallow hydrothermal system. Identifying the magmatic signature of volcanic gases is critical to relate their composition to properties of the magma (temperature, fO2, gas-melt segregation depth). We report measurements of the chemical composition and flux of the major gas species emitted from Turrialba Volcano during March 2013. Measurements were made of two vents in the summit region, one of which opened in 2010 and the other in 2012. We determined an average SO2 flux of 5.2 ± 1.9 kg s-1 using scanning ultraviolet spectroscopy, and molar proportions of H2O, CO2, SO2, HCl, CO and H2 ga…
Recombinant laccase from Pediococcus acidilactici CECT 5930 with ability to degrade tyramine
2017
Biogenic amines degradation by bacterial laccases is little known, so we have cloned and heterologously expressed, in E. coli, a new laccase from Pediococcus acidilactici CECT 5930 (Lpa5930), a lactic acid bacterium commonly found in foods able to degrade tyramine. The recombinant enzyme has been characterized by physical and biochemical assays. Here we report the optimization of expression and purification procedures of this laccase. DNA encoding sequence of laccase from P. acidilactici was amplified by PCR and cloned into the expression plasmid pET28a for induction by isopropyl-β-D-thiogalactoipyranoside. Protein expression was performed in E. coli BL21(DE3) harboring pGro7 plasmid expres…
Liquid chromatography-ultraviolet detection and quantification of heat-labile toxin produced by enterotoxigenic E. coli cultured under different cond…
2017
Abstract Enterotoxigenic Escherichia coli (ETEC) is the main bacterial cause of dehydrating infant diarrhoea in less-developed countries. Labile toxin (LT) is the major virulent factor of ETEC. Easy diagnostic tests are necessary to reduce the number of cases. Immunological methods have some drawbacks and also have important limitations. For that reason, a Liquid Chromatography coupled to UV detector technique (LC-UV) has been optimize to a rapid identification and quantification of LT from bacteria cultures. It is also important to know optimal conditions for LT and with this purpose several enterotoxigenic E. coli strains have been studied to determine the influence of glucose concentrati…
Emerging switchable ultraviolet photoluminescence in dehydrated Zn/Al layered double hydroxide nanoplatelets
2019
AbstractLayered double hydroxides show intriguing physical and chemical properties arising by their intrinsic self-assembled stacking of molecular-thick 2D nanosheets, enhanced active surface area, hosting of guest species by intercalation and anion exchanging capabilities. Here, we report on the unprecedented emerging intense ultraviolet photoluminescence in Zn/Al layered double hydroxide high-aspect-ratio nanoplatelets, which we discovered to be fully activated by drying under vacuum condition and thermal desorption as well. Photoluminescence and its quenching were reproducibly switched by a dehydration–hydration process. Photoluminescence properties were comprehensively evaluated, such a…
Kinetic evidence for interaction of TMPyP4 with two different G-quadruplex conformations of human telomeric DNA
2018
Background: Stabilization of G-quadruplex helices by small ligands has attracted growing attention because they inhibit the activity of the enzyme telomerase, which is overexpressed in> 80% cancer cells. TMPyP4, one of the most studied G-quadruplex ligands, is used as a model to show that the ligands can exhibit different binding features with different conformations of a human telomeric specific sequence. Methods: UV–Vis, FRET melting Assay, Isothermal Titration Calorimetry, Time-resolved Fluorescence lifetime, T-Jump and Molecular Dynamics. Results: TMPyP4 yields two different complexes with two Tel22 telomeric conformations in the presence of Na+ or K+. T-Jump kinetic experiments show th…
Biopreservation of Myoglobin in Crowded Environment: A Comparison between Gelatin and Trehalose Matrixes.
2017
Biopreservation by sugar and/or polymeric matrixes is a thoroughly studied research topic with wide technological relevance. Ternary amorphous systems containing both saccharides and proteins are extensively exploited to model the in vivo biopreservation process. With the aim of disentangling the effect of saccharides and polypeptidic crowders (such as gelatin) on the preservation of a model protein, we present here a combined differential scanning calorimetry and UV-vis spectrophotometry study on samples of myoglobin embedded in amorphous gelatin and trehalose + gelatin matrixes at different hydrations, and compare them with amorphous myoglobin-only and myoglobin-Trehalose samples. The res…
A UHPLC-UV Method to Quantify Skin Deposition and Transdermal Permeation of Tizanidine Hydrochloride
2015
Tizanidine hydrochloride is an α2-adrenergic agonist used for the symptomatic relief of spasticity associated with multiple sclerosis or with spinal cord injury or disease. The objective of this study was to develop an isocratic, robust and sensitive ultra-high performance liquid chromatography method using UV detection for use in a project to develop a transdermal therapeutic system to deliver tizanidine across the skin. Isocratic separation was achieved using a C18 column and a mobile phase comprising a 80:20 mixture of 0.004% trifluoroacetic acid in water and MeCN (pH* 3.2) at a flow rate of 0.2 mL min(-1) Tizanidine eluted at 1.499 min and the total run time was 2 min. The method was sp…
New algorithms for atmospheric correction and retrieval of biophysical parameters in earth observation : application to ENVISAT/MERIS data
2007
An algorithm for the derivation of atmospheric and surface biophysical products from the MEdium Resolution Imaging Spectrometer Instrument (MERIS) on board ENVIronmental SATellite (ENVISAT/MERIS) Level 1b data over land has been developed. Georectified aerosol optical thickness (AOT), columnar water vapor (CWV), spectral surface reflectance and chlorophyll fluorescence (CF) maps are generated. Emphasis has been put on implementing a robust software able to provide those products on an operational manner, making no use of ancillary parameters apart from those attached to MERIS images. For this reason, it has been named Self-Contained Atmospheric Parameters Estimation from MERIS data (SCAPE-M…