9,025 research outputs found

    Photonic band gaps analysis of Thue-Morse multilayers made of porous silicon

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    Dielectric aperiodic Thue-Morse structures up to 128 layers have been fabricated by using porous silicon technology. The photonic band gap properties of Thue-Morse multilayers have been theoretically investigated by means of the transfer matrix method and the integrated density of states. The theoretical approach has been compared and discussed with the reflectivity measurements at variable angles for both the transverse electric and transverse magnetic polarizations of light. The photonic band gap regions, wide 70 nm and 90 nm, included between 0 and 30°, have been observed for the sixth and seventh orders, respectively

    Deamidation at Asparagine and Glutamine As a Major Modification upon Deterioration/Aging of Proteinaceous Binders in MuralPaintings

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    Proteomic strategies are herein proved to be a complementary approach to the well established amino acid composition analysis for the characterization of the aging and deterioration phenomena occurring to proteinaceous materials in works-of-art. Amino acid analyses on several samples demonstrated that proteins in the frescoes from the Camposanto Monumentale in Pisa are deteriorated as revealed by the decrease in Met, Lys, and Tyr content and by the presence in all the samples of amino malonic acid as a result of Ser, Phe, and Cys oxidation. Proteomic analysis identified deamidation at Asn and Gln as a further major event occurred. This work paves the way to the exploitation of proteomic strategies for the investigation of the molecular effects of aging and deterioration in historical objects. Results show that proteomic searches for deamidation by liquid chromatography-tandem mass spectrometry (LC-MS/MS) could constitute a routine analysis for paintings or any artistic and historic objects where proteins are present. Peptides that can be used as molecular markers when casein is present were identified

    Breaking the symmetry of the graph colouring problem with genetic algorithms

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    The graph colouring problem is a widely studied combinatorial optimisation problem with a highly symmetric solution space. Many heuristics and search algorithms are unattractive for general solution, i.e. they generate poor approximate solutions, because they were originally designed for specific problem instances. Population-based approaches like genetic algorithms do not provide a good alternative because of the danger of recombining good individuals from different regions of the search space (having different symmetries) to produce poor offspring. This paper presents a genetic algorithm that breaks the symmetry of the graph colouring problem by fixing the colours of the nodes in a large clique of the graph. Experiments have been conducted on both structured and random graphs to demonstrate the effectiveness of the approach. 1 Introduction The ability to find quick and robust solutions to hard optimisation problems has been appreciated for long time since there are..

    Update on chronic rejection after intestinal transplant. An overview from experimental settings to clinical outcomes

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    Chronic rejection affects the long-term survival of solid-organ transplants, accounting for an incidence of between 5% and 10% after intestinal/multivisceral transplant. Because of unclear symptoms and signs and endoscopic findings, the diagnosis is often delayed. Presently, allograft removal represents the only available therapy due to the absence of effective pharmacologic approaches. Extensive research, through animal models, has been performed over the past 20 years to clarify the complex immune- and nonimmune-mediated mechanisms behind the development of chronic allograft enteropathy, with the aim of elucidating how to avert chronic rejection. The role of donor-specific antibodies and the way to challenge them in the clinic have gained acceptance among transplant centers as one of the main steps to prevent chronic rejection, although no common protocol exists that can be applied in a systematic fashion. The adjunct of a liver graft when retrans planting is needed in a sensitized recipient due to its protective effect against humoral immunity. Multicenter studies and clinical trials are required to better understand the pathogenesis of chronic rejection and to find the therapeutic answer to this clinical query
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