5,982 research outputs found

    Bioorthogonal catalytic activation of Platinum and Ruthenium anticancer complexes by FAD and flavoproteins

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    Recent advances in bioorthogonal catalysis promise to deliver new chemical tools for performing chemoselective transformations in complex biological environments. Herein, we report how FAD (flavin adenine dinucleotide), FMN (flavin mononucleotide), and four flavoproteins act as unconventional photocatalysts capable of converting PtIV and RuII complexes into potentially toxic PtII or RuII-OH2 species. In the presence of electron donors and low doses of visible light, the flavoproteins mini singlet oxygen generator (miniSOG) and NADH oxidase (NOX) catalytically activate PtIV prodrugs with bioorthogonal selectivity. In the presence of NADH, NOX catalyzes PtIV activation in the dark as well, indicating for the first time that flavoenzymes may contribute to initiating the activity of PtIV chemotherapeutic agents

    The interplay between double exchange, super-exchange, and Lifshitz localization in doped manganites

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    Considering the disorder caused in manganites by the substitution of Mn by Fe or Ga, we accomplish a systematic study of doped manganites begun in previous papers. To this end, a disordered model is formulated and solved using the Variational Mean Field technique. The subtle interplay between double exchange, super-exchange, and disorder causes similar effects on the dependence of T_C on the percentage of Mn substitution in the cases considered. Yet, in La2/3_{2/3}Ca1/3_{1/3}Mn1−y_{1-y}Gay_yO3_3 our results suggest a quantum critical point (QCP) for y≈0.1−0.2y\approx 0.1-0.2, associated to the localization of the electronic states of the conduction band. In the case of Lax_xCax_xMn1−y_{1-y}Fey_yO3_3 (with x=1/3,3/8x=1/3,3/8) no such QCP is expected.Comment: 6 pages + 3 postscript figures. Largely extended discussio

    Biological and Health-promoting Activity of Vinification Byproducts Produced in Spanish Vineyards

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    Several by-products are produced in the Spanish agricultural system. Among them, fresh and vinifiedgrape skins represent an abundant source of phenols with a potential nutraceutical value. Fresh grape skinextracts (FGSE) and vinification of grape skin extracts (VGSE) obtained by a microwave-assisted methodhave been chemically and biologically characterised. Their role in the maintenance of genetic stabilitywas stated by in vivo genotoxic and antigenotoxic evaluations (Drosophilla melanogaster wing spot test), aswell as by their potential chemopreventive effect (in an HL60 in vitro model). Total phenolic, anthocyaninand resveratrol contents were chemically characterised in the two extracts, showing some qualitativedifferences. Both extracts and resveratrol were not mutagenic in the Drosophila somatic mutation andrecombination tests, and exerted antigenotoxic activities against hydrogen peroxide. They also showedcytotoxic activity to HL60 leukaemia cells, with an IC50 of 4.5ÎŒL/mL, 4.6ÎŒL/mL and 98ÎŒM respectively andinduced apoptotic internucleosomic fragmentation in the HL60 cell line

    Element abundances in the metal rich open cluster NGC6253

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    We have carried out a big FLAMES survey of 10 Galactic open clusters aiming at different goals. One of them is the determination of chemical abundances, in order to put constraints on the radial metallicity gradient in the disk and its evolution. One of the sample clusters is the very metal rich NGC 6253. We have obtained UVES high resolution spectra of seven candidate cluster members (from the turn off up to the red clump) with the goal of determining the chemical composition of NGC 6253 and to investigate its origin and role in the interpretation of the radial metallicity gradient in the disk. Equivalent width analysis and spectral synthesis were performed using MOOG and Kurucz model atmospheres. We derived abundances of Fe, alpha- and Fe-peak elements, the light element Na and the s-process element Ba. Excluding two likely non-members and the clump giant, whose metallicity from equivalent widths is overestimated, we find an average [Fe/H]=+0.36+/-0.07 (rms) for the cluster. For most of the other elements we derive solar abundance ratios.Comment: accepted by A&A (02/01/2007), 21 pages, 11 ps figure

    La cueva de el Sidron (Borines, Piloña, Asturias) : primeros resultados

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    Se exponen los resultados preliminares de las excavaciones arqueolĂłgicas llevadas a cabo en la Cueva de El SidrĂłn entre 2000 y 2002, de acuerdo con los tres objetivos principales que conciernen al registro fĂłsil humano: las caracterĂ­sticas antropolĂłgicas, cĂłmo y cuĂĄndo llegaron allĂ­ y la relaciĂłn entre fĂłsiles y cultura. Las primeras conclusiones obtenidas son que los restos humanos pertenecen al Neandertal, que el registro arqueolĂłgico corresponde a un tecno-complejo del PaleolĂ­tico Medio y que estĂĄn en posiciĂłn secundaria.We expose the preliminary results ofthe archaeological excavations developed between 2000-2002 in SidrĂłn's Cave, according to the three main objectives that concern the human fossil record: the anthropological characteristics, how and when they arrived there and the relation between fossils and culture. We conclude preliminarily that the record belongs to Horno Neanderthalensis, archeological remains to the Middle Paleolithic techno-complex, and they are in a secondary [email protected]

    Non-Markovian stochastic description of quantum transport in photosynthetic systems

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    We analyze several aspects of the transport dynamics in the LH1-RC core of purple bacteria, which consists basically in a ring of antenna molecules that transport the energy into a target molecule, the reaction center, placed in the center of the ring. We show that the periodicity of the system plays an important role to explain the relevance of the initial state in the transport efficiency. This picture is modified, and the transport enhanced for any initial state, when considering that molecules have different energies, and when including their interaction with the environment. We study this last situation by using stochastic Schr{\"o}dinger equations, both for Markovian and non-Markovian type of interactions.Comment: 21 pages, 5 figure

    Mechanical behavior of asphalt mixtures containing silica gels as warm additives

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    This paper presents the results of a study of some compounds capable of absorbing water into their structure (silica gel), as potential foaming binders. Asphalt mixtures were manufactured at different manufacturing and compaction temperatures, using four different silica gels. Static and dynamic tests were carried out to determine their behavior in asphalt mixtures. The results were compared with those obtained using hot-mix asphalt and warm-mix asphalt manufactured with zeolite. The lab results showed a similar behavior of asphalt mixtures containing either silica gel or zeolite.The research presented herein was sponsored by the Research Office of Universidad de La Frontera (DIUFRO) under the project number DI15-0089

    Analytical methods in wineries: is it time to change?

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    A review of the methods for the most common parameters determined in wine—namely, ethanol, sulfur dioxide, reducing sugars, polyphenols, organic acids, total and volatile acidity, iron, soluble solids, pH, and color—reported in the last 10 years is presented here. The definition of the given parameter, official and usual methods in wineries appear at the beginning of each section, followed by the methods reported in the last decade divided into discontinuous and continuous methods, the latter also are grouped in nonchromatographic and chromatographic methods because of the typical characteristics of each subgroup. A critical comparison between continuous and discontinuous methods for the given parameter ends each section. Tables summarizing the features of the methods and a conclusions section may help users to select the most appropriate method and also to know the state-of-the-art of analytical methods in this area

    Transiting exoplanets from the CoRoT space mission IX. CoRoT-6b: a transiting `hot Jupiter' planet in an 8.9d orbit around a low-metallicity star

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    The CoRoT satellite exoplanetary team announces its sixth transiting planet in this paper. We describe and discuss the satellite observations as well as the complementary ground-based observations - photometric and spectroscopic - carried out to assess the planetary nature of the object and determine its specific physical parameters. The discovery reported here is a `hot Jupiter' planet in an 8.9d orbit, 18 stellar radii, or 0.08 AU, away from its primary star, which is a solar-type star (F9V) with an estimated age of 3.0 Gyr. The planet mass is close to 3 times that of Jupiter. The star has a metallicity of 0.2 dex lower than the Sun, and a relatively high 7^7Li abundance. While thelightcurveindicatesamuchhigherlevelof activity than, e.g., the Sun, there is no sign of activity spectroscopically in e.g., the [Ca ] H&K lines
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