Search results for "ULTRAVIOLET"

Laminar Micrite Crusts and Associated Foreslope Processes, Red Sea

1991

ABSTRACT Forereef slopes in the Red Sea of Sudan exhibit a uniform biozonation that is independent from the topography of the slopes. Below - 120 m, ledges protrude horizontally from sleep cliffs of barrier reefs and atolls as well as from patches of in situ lithified slope sediment on inclined fringing reef slopes. Free surfaces and cavities within these ledges are partly covered by laminar micrite crusts of 7-20 mm thickness. The ledges are formed by an organic framework of living azooxanthellate corals, bryozoans, serpulids and fossil red algae. They are affected by repeated episodes of boring, infilling, and cementation which obliterate much of the original fabric. Concomitant cementati…

Vulcamera: a program for measuring volcanic SO2 using UV cameras

2011

We report here on Vulcamera, a stand-alone program for the determination of volcanic SO2  fluxes using ultraviolet cameras. The code enables field image acquisition and all the required post-processing operations.<br />

Forward light-by-light scattering and electromagnetic correction to hadronic vacuum polarization

2023

Lattice QCD calculations of the hadronic vacuum polarization (HVP) have reached a precision where the electromagnetic (e.m.) correction can no longer be neglected. This correction is both computationally challenging and hard to validate, as it leads to ultraviolet (UV) divergences and to sizeable infrared (IR) effects associated with the massless photon. While we precisely determine the UV divergence using the operator-product expansion, we propose to introduce a separation scale $\Lambda\sim400\;$MeV into the internal photon propagator, whereby the calculation splits into a short-distance part, regulated in the UV by the lattice and in the IR by the scale $\Lambda$, and a UV-finite long-di…

Examples of UV–Vis profiles use as tool for evidence of the metallophthalocyanines transformation

2017

Abstract The UV–Vis spectra for a set of MPcs (Mmetal, Pc = phthalocyanine ligand), i.e.: In(III)PcI (1), Hf(IV)PcI2Pht (Pht = phthalonitrile) (2), Sn(II)Pc (3), Sn(IV)PcI2 (4), and Ge(IV)PcI2 (5) have been examined in two solvents, O-donative acetylacetone, and non-coordinative benzene. The UV–Vis spectra in Hacac solution of 1,2 and 4,5 shows that the axially ligated iodine atoms are replaced by (acac)− anions of the solvent, whereas in 3 the oxygen donors of the solvent causing the auto-oxidation of Sn(II) to Sn(IV) ions and as a result the Sn(II)Pc is transformed into the Sn(IV)Pc(acac)2. The chloride complexes of the 1–5 compounds are formed at Hacac solution after acidification by hyd…

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

Cathodoluminescence and photoluminescence study of trap centers in amorphous silicon oxynitride

2002

Amorphous silicon oxynitride (a-SiO/sub x/N/sub y/) films with different compositions were prepared using low-pressure chemical vapor deposition (LPCVD) technique, The cathodoluminescence and photoluminescence of this samples were measured from the red band to the ultraviolet band to study the trap centers in silicon oxynitride. A 1.8-1.9 eV band was found and is attributed to the oxygen and nitrogen atoms with unpaired electrons whereas the 2.7 eV band is attributed to two-fold coordinated silicon atoms with two electrons. The 5.4 eV shoulder is due to the peroxy radicals and other ultraviolet bands are supposed to due due to the Si-Si bonds.

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…