5,982 research outputs found
Bioorthogonal catalytic activation of Platinum and Ruthenium anticancer complexes by FAD and flavoproteins
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
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
LaCaMnGaO our results suggest a quantum
critical point (QCP) for , associated to the localization of
the electronic states of the conduction band. In the case of
LaCaMnFeO (with ) 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
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
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
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
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
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
Meloidogyne and Pratylenchus species in sugarcane fields in the state of Alagoas, Brazil
Analytical methods in wineries: is it time to change?
A review of the methods for the most common parameters determined in wineânamely, ethanol, sulfur dioxide, reducing sugars, polyphenols, organic acids, total and volatile acidity, iron, soluble solids, pH, and colorâreported 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
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 Li abundance. While
thelightcurveindicatesamuchhigherlevelof activity than, e.g., the Sun, there is
no sign of activity spectroscopically in e.g., the [Ca ] H&K lines
- âŠ