21 research outputs found

    Transparent nanometric organic luminescent films as UV-active components in photonic structures

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    A new kind of visible-blind organic thin-film material, consisting of a polymeric matrix with a high concentration of embedded 3-hydroxyflavone (3HF) dye molecules, that absorbs UV light and emits green light is presented. The thin films can be grown on sensitive substrates, including flexible polymers and paper. Their suitability as photonic active components photonic devices is demonstrated. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    Label-free optical biosensing with slot-waveguides.

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    We demonstrate label-free molecule detection by using an integrated biosensor based on a Si3N4 /SiO2 slotwaveguide microring resonator. Bovine serum albumin (BSA) and anti-BSA molecular binding events on the sensor surface are monitored through the measurement of resonant wavelength shifts with varying biomolecule concentrations. The biosensor exhibited sensitivities of 1.8 and 3.2 nm/ _ng/mm2_ for the detection of anti-BSA and BSA, respectively. The estimated detection limits are 28 and 16 pg/mm2 for anti-BSA and BSA, respectively, limited by wavelength resolutio

    Ultrahigh Sensitivity Slot-Waveguide Biosensor on a Highly Integrated Chip for Simultaneous Diagnosis of Multiple

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    SABIO is a multidisciplinary project involving the emerging fields of micro-nanotechnology, photonics, fluidics and bio-chemistry, targeting a contribution to the development of intelligent diagnostic equipment through the demonstration of a compact polymer based and silicon-based CMOS-compatible micro-nano system. It integrates optical biosensors for label-free biomolecular recognition based on a novel photonic structure named slot-waveguide with immobilized bimolecular receptors on its surface. The slot-waveguides provide high optical intensity in a sub wavelength-size low refractive index region (slot-region) sandwiched between two high refractive index strips (rails) [1] leading to an enhanced interaction between the optical probe and biomolecular complexes (antibody-antigen). As such a biosensor is predicted to exhibit a surface concentration detection-limit lower than 1 pg/mm2, state-of-the-art in label free integrated optical biosensors, as well as the possibility of multiplexed assay, which, together with reduced reaction volumes, leads to the ability to perform rapid multi-analytesensing and comprehensive tests. This offers the further advantageous possibility of assaying several parameters simultaneously and consequently, statistical analysis of these results can potentially increase the reliability and reduce the measurement uncertainty of a diagnostic over single-parameter assays. In addition, the SABIO micro-nano system device applied to its novel protein-based diagnostic technology has the potential to be fast and easy to use, making routine screening or monitoring of diseases more cost-effective

    Maternal Undernutrition and Long-term Effects on Hepatic Function

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    Undernutrition in utero, regardless of the source, can impair proper liver development leading to long-term metabolic dysfunction. Understanding the molecular mechanisms underlying how nutritional deficits during perinatal life lead to permanent alterations in hepatic gene expression will provide better therapeutic strategies to alleviate the undernourished liver in postnatal life. This chapter addresses the different experimental models of undernutrition in utero, and highlights the direct and indirect mechanisms involved leading to metabolic diseases in the liver. These include hypoxia, oxidative stress, epigenetic alterations, and endoplasmic reticulum (ER) stress. In addition, promising perinatal nutritional and pharmaceutical interventions are highlighted which illustrate how the placidity of the developing liver can be exploited to prevent the onset of long-term metabolic disease

    Predator traits determine food-web architecture across ecosystems

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    Predator–prey interactions in natural ecosystems generate complex food webs that have a simple universal body-size architecture where predators are systematically larger than their prey. Food-web theory shows that the highest predator–prey body-mass ratios found in natural food webs may be especially important because they create weak interactions with slow dynamics that stabilize communities against perturbations and maintain ecosystem functioning. Identifying these vital interactions in real communities typically requires arduous identification of interactions in complex food webs. Here, we overcome this obstacle by developing predator-trait models to predict average body-mass ratios based on a database comprising 290 food webs from freshwater, marine and terrestrial ecosystems across all continents. We analysed how species traits constrain body-size architecture by changing the slope of the predator–prey body-mass scaling. Across ecosystems, we found high body-mass ratios for predator groups with specific trait combinations including (1) small vertebrates and (2) large swimming or flying predators. Including the metabolic and movement types of predators increased the accuracy of predicting which species are engaged in high body-mass ratio interactions. We demonstrate that species traits explain striking patterns in the body-size architecture of natural food webs that underpin the stability and functioning of ecosystems, paving the way for community-level management of the most complex natural ecosystems

    Food restriction alters pregnancy-associated changes in IGF and IGFBP in the guinea pig

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    The effect of moderate food restriction on pregnancy-associated changes in weight gain, body composition, and circulating insulin-like growth factors (IGF) I and II and IGF-binding proteins (IGFBP)-1 through-4 and their relationship was determined in the guinea pig. Pregnancy did not stimulate weight gain but reduced fat deposition in ad libitum-fed animals and increased weight gain and fat deposition in food-restricted animals relative to their respective virginal group. Pregnancy increased the abundance of circulating IGF-I regardless of food intake and increased that of IGF-II in food-restricted animals only. Pregnancy also increased circulating IGFBP-1 and -2 in ad libitum-fed and food-restricted animals and IGFBP-4 in ad libitum-fed animals. Multiple regression analysis showed that maternal weight gain was negatively associated with circulating IGF-II and IGFBP-2. Fetal weight was positively associated with maternal circulating IGF-II and negatively associated with maternal circulating IGFBP-1 and -2. Significant interactions indicate, however, that the role of IGF-II and IGFBP-1 on fetal growth is dependent on the nutritional status of the mother
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