Search results for " Ultraviolet"

A study of VUV emission and the extracted electron-ion ratio in hydrogen and deuterium plasmas of a filament-driven H−/D− ion source

2019

Vacuum ultraviolet (VUV) emission diagnostics for studying differences of electron impact processes in hydrogen and deuterium plasmas are presented. The method is applied to study a filament driven multicusp arc discharge negative ion source by comparing the VUV-emission intensities of different emission bands and extracted currents of H−/D− ions and electrons. It was found that the ratio of coextracted electrons to extracted ions is four times higher for deuterium than for hydrogen. No significant differences of the VUV-spectra or volumetric rates of ionization, excitation, production of high vibrational states, and dissociation were found between the plasmas of the two isotopes. The volum…

Estudio del espesor óptico de nubes a partir de radiación solar

2015

El objetivo general de este trabajo es el cálculo del espesor óptico de nubes para nubes bajas y medias formadas por gotas de agua en la ciudad de Burjassot (Valencia), mediante un método de minimización. Los espesores han sido obtenidos tanto para cielos cubiertos como para cielos parcialmente nubosos con el Sol oculto por las nubes, a partir de medidas de irradiancia eritemática (UVER) e irradiancia solar total a nivel de suelo. Para ello se han utilizado dos modelos de transferencia radiativa que presuponen capas de nubes homogéneas plano-paralelas. También se han obtenido diferentes relaciones empíricas entre el espesor óptico de nubes obtenido y diferentes factores de transmisividad at…

Ultraviolet camera measurements of passive and explosive (Strombolian) sulphur dioxide emissions at Yasur volcano, Vanuatu

2020

Here, we present the first ultraviolet (UV) camera measurements of sulphur dioxide (SO2) flux from Yasur volcano, Vanuatu, for the period 6–9 July 2018. These data yield the first direct gas-measurement-derived calculations of explosion gas masses at Yasur. Yasur typically exhibits persistent passive gas release interspersed with frequent Strombolian explosions. We used compact forms of the “PiCam” Raspberry Pi UV camera system [1,2] powered through solar panels to collect images. Our daily median SO2 fluxes ranged from 4 to 5.1 kg s−1, with a measurement uncertainty of −12.2% to +14.7%, including errors from the gas cell calibration drift, uncertainties in plume direction and distance, and…

Indagini diagnostiche non invasive sui dipinti murali della Villa Romana del Casale di Piazza Armerina

2007

Il contributo delle indagini ottiche non invasive per la pulitura del statua marmorea di S. Michele Arcangelo di Palazzo Abatellis (Palermo)

2007

Properties of a triazolopyridine system as a molecular chemosensor for metal ions, anions, and amino acids.

2006

The characteristics as a chemosensor of the compound 3-methyl-6,8-di(2-pyridyl)-[1,2,3]triazolo[5',1':6,1]pyrido[2,3-]pyrimidine (1) have been analyzed. Interaction with Cu(2+) produces a quenching of the fluorescence, while interaction with Zn(2+) leads to a quenching of the fluorescence followed by a bathochromic shift. The crystal structure of the Zn(1)(H(2)O)(3)(ClO(4))(2) x H(2)O complex shows the coordination of Zn(2+) through the terpyridine moiety. The octahedral site is completed by three water molecules. Interactions of the Zn(2+) complex with the anions sulfate, nitrate, nitrite, and dihydrogenphosphate in ethanol produce hypsochromic shifts and restoration of the fluorescence wh…

Synthesis, Characterization, and Cu(2+) Coordination Studies of a 3-Hydroxy-4-pyridinone Aza Scorpiand Derivative.

2016

The synthesis, acid-base behavior, and Cu(2+) coordination chemistry of a new ligand (L1) consisting of an azamacrocyclic core appended with a lateral chain containing a 3-hydroxy-2-methyl-4(1H)-pyridinone group have been studied by potentiometry, cyclic voltammetry, and NMR and UV-vis spectroscopy. UV-vis and NMR studies showed that phenolate group was protonated at the highest pH values [log K = 9.72(1)]. Potentiometric studies point out the formation of Cu(2+) complexes of 1:2, 2:2, 4:3, 1:1, and 2:1 Cu(2+)/L1 stoichiometries. UV-vis analysis and electrochemical studies evidence the implication of the pyridinone moieties in the metal coordination of the 1:2 Cu(2+)/L1 complexes. L1 shows …

One pot light assisted green synthesis, storage and antimicrobial activity of dextran stabilized silver nanoparticles.

2014

Background Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report green synthesis of silver nanoparticles (Ag NPs) mediated with dextran. Dextran was used as a stabilizer and capping agent to synthesize Ag NPs using silver nitrate (AgNO3) under diffused sunlight conditions. Results UV–vis spectra of as synthesized Ag nanoparticles showed characteristic surface plasmon band in the range from ~405-452 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies showed spherical Ag NPs in the size regime of ~50-70 nm. Face centered cubic lattice of Ag NPs was confirmed by powder X-ray diffraction (PXRD…

Effects of diazinon exposure on cholinesterase activity in different tissues of European eel (Anguilla anguilla).

1996

Cholinesterase (ChE) activity was measured in brain, plasma, and whole eye of Anguilla anguilla experimentally exposed to a sublethal concentration of 0.042 mg/liter (0.50 of the 96-hr LC50) of the organophosphorous pesticide diazinon. Whole eye was the tissue which revealed higher values of ChE activity (8.17 micromol/min/g) in nonexposed animals. Brain, plasma, and whole eye ChE activity of A. anguilla was inhibited at 6, 24, 48, 72, and 96 hr of diazinon exposure. Pesticide induced significant inhibitory effects on the ChE activity of this species ranging from >70% inhibition in brain tissue to >90% in plasma samples. Brain and plasma presented technical difficulties in their collection.…

Use of a three-factor interpretive optimisation strategy in the development of an isocratic chromatographic procedure for the screening of diuretics …

2000

Screening of diuretics in urine is feasible through direct injection of the samples into the chromatographic system and isocratic reversed-phase liquid chromatography (RPLC) with micellar-organic mobile phases of sodium dodecyl sulfate (SDS) and 1-propanol. The surfactant coverage of the chromatographic column makes the addition of organic competing amines less necessary than in conventional aqueous-organic RPLC to achieve well-shaped peaks. Also, the range of elution strengths of micellar mobile phases required to elute mixtures of hydrophobic and hydrophilic diuretics is smaller. This allows the isocratic separation of the diuretics within adequate analysis times. An interpretive methodol…