Propriedades luminescentes de polioxometalato contendo európio(III) correlacionadas à sua conformação em sólido estendido e em filmes auto-organizados de Langmuir e Langmuir-Blodgett

Pós-graduação em Química - IQ

Sensores eletroquímicos baseados em eletrodos de pasta de carbono modificados pela adição de precursores de silicatos de bário dopados com Európio (III)

Pós-graduação em Química - IBILCE

Complexos de zinco(II), de európio(III) e heterobimetálico com os ácidos tiofeno 2 e 3-carboxílico. Síntese, caracterização e propriedades luminescentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Luminescência e propriedades estruturais de 'LI''TA'O IND.3'nanoestruturado dopado com európio (III) e magnésio

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Interaction of metal ions with nucleic acids and related compounds. II. Studies on Au(III)-nucleic acid system

The nature of interaction of Au(III) with nucleic acids was studied by using methods such as uv and ir spectrophotometry, viscometry, pH titrations, and melting-temperature measurements. Au(III) is found to interact slowly with nucleic acids over a period of several hours. The uv spectra of native calf-thymus DNA 9pH 5.6 acetate buffer containing (0.01M NaCIO4) showed a shift in λ max to high wavelengths and an increase in optical density at 260 nm. There was a fourfold decrease in viscosity (expressed as ηsp/c). The reaction was faster at pH 4.0 and also with denatured DNA (pH 5.6) and whole yeast RNA (pH 5.6). The order of preference of Au(III) (as deduced from the time of completion of reaction) for the nucleic acids in RNA > denatured DNA > DNA. The reaction was found to be completely reversible with respect KCN. Infrared spectra of DNA-Au(III) complexes showed binding to both the phosphate and bases of DNA. The same conclusions were also arrived at by melting-temperature studies of Au(III)-DNA system. pH titrations showed liberation of two hydroxylions at r = 0.12 [r = moles of HAuCl4 added per mole of DNA-(P)] and one hydrogen ion at r = 0.5. The probable binding sites could be N(1)/N(7) of adenine, N(7) and/or C(6)O of guanine, N(3) of cytosine and N(3) of thymine. DNAs differing in their (G = C)-contents [Clostridium perfingens DNA(G = C, 29%), salmon sperm DNA (G + C, 42%) and Micrococcus lysodeikticus DNA(G + C, 29%), salmon sperm DNA (G = C, 72%)] behaved differently toward Au(III). The hyperchromicity observed for DNAs differing in (G + C)-content and cyanide reversal titrations indicate selectivity toward ( A + T)-rich DNA at lw values of r. Chemical analysis and job's continuous variation studies indicated the existence of possible complexes above and below r = 1. The results indicate that Au(III) ions probably bind to hte phosphate group in the initial stages of the reaction, particularly at low values of r, and participation of the base interaction also increases. Cross-linking of the two strands by Au(III) may take place, but a complete collapse of the doulbe helix is not envisaged. It is probable that tilting of the bases or rotaiton of the bases around the glucosidic bond, resulting in a significant distrotion of the double helix, might take place due to binding of Au(III) to DNA.

Etymological notes on Aleut (III). With methodological notes on (Eskimo-Aleut) historical linguistics

[EN] The goal of this contribution is twofold: on the one hand, to review two relatively recent contributions in the field of Eskimo-Aleut historical linguistics in which it is proposed that Eskimo-Aleut languages are related genealogically to Wakashan (Holst 2004) and?/or Nostratic (Krougly-Enke 2008). These contributions can be characterized by saying that their authors have taken little care to be diligent and responsible in the application of the comparative method, and that their familiarity with the languages involved is insufficient. Eskimo-Aleut languages belong to a very exclusive group of language families that have been (and still are) used, sometimes compulsively, in the business of so-called “long-range comparisons”. Those carrying out such studies are very often unaware of the most basic facts regarding the philological and linguistic traditions of those languages, as a result of what mountains of very low quality works with almost no-relevancy for the specialist grow every year to the desperation of the scientific community, whose attitude toward them ranges from the most profound indifference to the toughest (and most explicit) critical tone. Since Basque also belongs to this group of “compare-with-everything-you-come- across” languages, it is my intention to provide the Basque readership with a sort of “pedagogical case” to show that little known languages, far from underrepresented in the field, already have a very long tradition in historical and comparative linguistics, i.e. nobody can approach them without previous acquaintance with the materials. Studies dealing with the methodological inappropriateness of the Moscow School’s Nostratic hypothesis or the incorrectness of many of the proposed new taxonomic Amerindian subfamilies (several of them involving the aforementioned Wakashan languages), that is to say, the frameworks on which Krougly-Enke and Holst work, respectively, are plenty (i.a. Campbell 1997: 260-329, Campbell & Poser 2008: 234-96), therefore there is no reason to insist once more on the very same point. This is the reason why I will not discuss per se Eskimo-Aleut–Wakashan or Eskimo-Aleut–Nostratic. On the contrary, I will focus attention upon very concrete aspects of Krougly-Enke and Holst´s proposals, i.e. when they work on “less ambitious” problems, for example, dealing with the minutiae of internal facts or analyzing certain words from the sole perspective of Eskimo-Aleut materials (in other words, those cases in which even they do not invoke the ad hoc help of Nostratic stuff). I will try to explain why some of their proposals are wrong, demonstrate where the problem lies, and fix it if possible. In doing so, I will propose new etymologies in an attempt at showing how we may proceed. The main difference between this and handbook examples lies in the reality of what we are doing: this is a pure etymological exercise from beginning to end. I will try to throw a bit of light on a couple of problematic questions regarding Aleut historical phonology, demonstrating how much work should be done at the lowest level of the Eskimo-Aleut pyramid; it is technically impossible to reach the peak of the pyramid without having completed the base. As far as Aleut is regarded, I will mainly profit not only from the use of the traditional philological analysis of Aleut (and, eventually, of Eskimo) materials, but also of diachronic typology, bringing into discussion what in my opinion seems useful, and in some cases I think decisive, parallels. It is worth noting that this paper makes up yet another part of a series of exploratory works dealing with etymological aspects of the reconstruction of Proto-Eskimo-Aleut, with special emphasis on Aleut (vid. i.a. Alonso de la Fuente 2006/2007, 2008a, 2008b, 2010a), whose main goal is to become the solid basis for an etymological dictionary of the Aleut language, currently in progress.

MOCVD growth of high quality crack-free GaN on Si(III) substrates

High quality crack free GaN epilayers were grown on Si(111) substrates. Low temperature AlN interlayer grown under low V/III ratio was used to effectively eliminate the formation of micro-cracks. It is found that tensile stress in the GaN epilayer decreases as the N/Al ratio decreases used for AlN interlayer growth. The high optical and structural qualities of the GaN/Si samples were characterized by RBS, PL and XRD measurements. The RT-PL FWHM of the band edge emission is only 39.5meV The XRD FWHM of the GaN/Si sample is 8.2arcmin, which is among the best values ever reported.

Speciation of Chlorometallate Ionic Liquids Based on Gallium(III) and Indium(III)

A range of ionic liquids was prepared by mixing 1-alkyl-3-methylimidazolium chloride with gallium(III) chloride or indium(III) chloride in various ratios, producing both acidic and basic compositions. Their speciation was investigated using Ga-71 NMR or In-115 NMR spectroscopy, as well as extended X-ray absorption fine structure. Polynuclear Lewis acidic anions, [MxCl3x+1](-), were found in chlorogallate(III) ionic liquids, but not in chloroindate(III) systems.

Supramolecular assemblies of metal ions in complex bimetallic and trimetallic salts based on hexacyanoferrate(III) ion

Two complex heterometallic salts with formulae Tl-6[Fe(CN)(6)](1) (33)(NO3)(OH) (1) and [Co(bpy)(2)(CN)(2)](2){[Ag(CN)(2)](0) (5)[Fe(CN)(6)](0) (5)} 8H(2)O (2) have been synthesized and fully characterized Single crystal X-ray analyses reveal that compound 1 is comprised of discrete Tl+ cations and [Fe(CN)(6)](3-) anions together with OH- and NO3- anions Compound 2 contains [Co(bpy)(2)(CN)(2)](+) cations and {[Ag(CN)(2)][Fe(CN)(6)]}(-) anions together with eight molecules of water of crystallization Both structures form unprecedented three-dimensional supramolecular networks via non covalent interactions Another important observation is that the stereochemically active inert (lone) pair present on Tl+ plays little role in controlling the structure of 1 The water molecules in 2 play important roles in providing stability organizing a supramolecular network through hydrogen bonding In the syntheses of 1 and 2 Fe(II) is oxidized to Fe(III) and Co(II) to Co(III) respectively facilitating the formation of the salts that are obtained Both compounds exhibit photoluminescence emission in solution near the visible region.