Search results for "ultraviolet"

Mapping accretion and its variability in the young open cluster NGC 2264: A study based on u-band photometry

2014

We aim at characterizing the accretion properties of several hundred members of the star-forming cluster NGC 2264 (3 Myr). We performed a deep u,g,r,i mapping and a simultaneous u+r monitoring of the region with CFHT/MegaCam in order to directly probe the accretion process from UV excess measurements. Photometric properties and stellar parameters are determined homogeneously for about 750 monitored young objects, spanning the mass range 0.1-2 Mo. About 40% are classical (accreting) T Tauri stars, based on various diagnostics (H_alpha, UV and IR excesses). The remaining non-accreting members define the (photospheric+chromospheric) reference UV emission level over which flux excess is detecte…

Lyman break and ultraviolet-selected galaxies at z ~ 1 - II. PACS 100μm/160μm FIR detections

2013

In this work, we report the Photodetector Array Camera and Spectrometer (PACS) 100 μm/160 μm detections of a sample of 42 GALEX-selected and far-infrared (FIR)-detected Lyman break galaxies (LBGs) at z ~ 1 located in the Cosmic Evolution Survey (COSMOS) field and analyse their ultraviolet (UV) to FIR properties. The detection of these LBGs in the FIR indicates that they have a dust content high enough so that its emission can be directly detected. According to a spectral energy distribution (SED) fitting with stellar population templates to their UV-to-near-IR observed photometry, PACS-detected LBGs tend to be bigger (Reff ~ 4.1 kpc), more massive [log (M*/M⊙) ~ 10.7], dustier [Es(B - V) ~ …

Binding Mode and Selectivity of a Scorpiand-Like Polyamine Ligand to Single- and Double-Stranded DNA and RNA: Metal- and pH-Driven Modulation

2017

The interaction of a polyazacyclophane ligand having an ethylamine pendant arm functionalized with an anthryl group (L), with the single-stranded polynucleotides polyA, polyG, polyU, and polyC as well as with the double-stranded polynucleotides polyA-polyU, poly(dAT)(2), and poly(dGC)(2) has been followed by UV/Vis titration, steady state fluorescence spectroscopy, and thermal denaturation measurements. In the case of the single-stranded polynucleotides, the UV/Vis and fluorescence titrations permit to distinguish between sequences containing purine and pyrimidine bases. For the double-stranded polynucleotides the UV/Vis measurements show for all of them hypochromicity and bathochromic shif…

Eukaryotic tRNAs(Pro): primary structure of the anticodon loop; presence of 5-carbamoylmethyluridine or inosine as the first nucleoside of the antico…

1990

The modified nucleoside U*, located in the first position of the anticodon of yeast, chicken liver and bovine liver tRNA(Pro) (anticodon U*GG), has been determined by means of TLC, HPLC, ultraviolet spectrum and gas chromatography-mass spectrometry. The structure was established as 5-carbamoylmethyluridine (ncm5U). In addition, we report on the primary structures of the above-mentioned tRNAs as well as those which have the IGG anticodon. In yeast, the two tRNA(Pro) (anticodons U*GG and IGG) differ by eight nucleotides, whereas in chicken and in bovine liver, both anticodons are carried by the same 'body tRNA' with one posttranscriptional exception at position 32, where pseudouridine is asso…

Synthesis, structure, and nuclease properties of several binary and ternary complexes of copper(II) with norfloxacin and 1,10 phenantroline

2007

Three new binary Cu(II) complexes of norfloxacin have been synthesized and characterized. We also report the synthesis, characterization and X-ray crystallographic structures of a new binary compound, [Cu(HNor)(2)]Cl(2).2H(2)O (2) and two new ternary complexes norfloxacin-copper(II)-phen, [Cu(Nor)(phen)(H(2)O)](NO(3)).3H(2)O (4), and [Cu(HNor)(phen)(NO(3))](NO(3)).3H(2)O (5). The structure of 2 consists of two crystallographically independent cationic monomeric units of [Cu(HNor)(2)](2+), chloride anions, and uncoordinated water molecules. The Cu(II) ion is placed at a center of symmetry and is coordinated to two norfloxacin ligands which are related through the inversion center. The struct…

Study of Confined 5-Aza[5]helicene in Ytterbium(III) Bis(2-ethylhexyl) Sulfosuccinate Reversed Micelles

2007

Some relevant physicochemical properties of 5-aza[5]helicene (H5) in solutions of ytterbium bis(2-ethylhexyl) sulfosuccinate (Yb(DEHSS)3) reversed micelles have been investigated by UV-vis-NIR, photoluminescence, and FT-IR techniques with the aim of emphasizing the role played by specific Yb(III)/H5 interactions and confinement effects as driving forces of its binding to reversed micelles, preferential solubilization site, and local photophysical properties. It has been found that the binding strength of 5-aza[5]helicene to reversed micelles, triggered by steric and orientational constrains as well as the water content, is mainly regulated by its interaction with the Yb(III) counterion. Mor…

Interaction between biotin lipids and streptavidin in monolayers: formation of oriented two-dimensional protein domains induced by surface recognitio…

1989

Highly specific ligand-receptor interactions generally characterize surface recognition reactions. Such processes can be simulated by streptavidin-biotin-specific binding. Biotin lipids have thus been synthesized, and their interaction with streptavidin (or avidin) at the air-water interface was directly shown by measurement of surface pressure isotherms and fluorescence microscopy. These proteins interact with the biotin lipid monolayer via specific binding or nonspecific adsorption. Both phenomena were clearly distinguished by use of the inactivated form of streptavidin. The binding of fluorescein-labeled streptavidin to monolayers was also directly observed by fluorescence microscopy. Th…

Incorporation of ATP synthetase into long-term stable liposomes of a polymerizable synthetic sulfolipid

1981

1H NMR and UV-vis spectroscopic characterization of sulfonamide complexes of nickek(II)-carbonic anhydrase. Resonance assignments based on NOE effects

1992

The binding of acetazolamide, p-fluorobenzensulfonamide, p-toluenesulfonamide, and sulfanilamide to nickel(II)-substituted carbonic anhydrase II has been studied by 1H NMR and electronic absorption spectroscopies. These inhibitors bind to the metal ion forming 1:1 complexes and their affinity constants were determined. The 1H NMR spectra of the formed complexes show a number of isotropically shifted signals corresponding to the histidine ligands. The complexes with benzene-sulfonamides gave rise to very similar 1H NMR spectra. The NMR data suggest that these aromatic sulfonamides bind to the metal ion altering its coordination sphere. In addition, from the temperature dependence of 1H NMR s…

Synthesis, Optical and Electrical Properties of Oligo(phenylenevinylene)s Substituted with Electron-Accepting Sulfonyl Groups

2010

Oligo(phenylenevinylene)s (OPV) composed of five rings and electron donating or withdrawing sulfonyl substituents on the central and lateral rings have been investigated. Two strategies were used for the syntheses of the C2-symmetrical OPVs both include PO-activated olefinations as central steps. Six flexible side chains guarantee good solubility in toluene or dichloromethane. In solution and in films stabilised by polystyrene (60%), the chromophores are strongly fluorescent, with emissions in the violet-blue domain from solutions and in the green to orange region from solid films. The redox potentials, determined by cyclic voltammetry, and the optical properties are strongly depending on t…