3,042 research outputs found

    Catalysts for polyimide foams from aromatic isocyanates and aromatic dianhydrides

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    Polyimide foam products having greatly improved burn-through and flame-spread resistance are prepared by the reaction of aromatic polyisocyanates with aromatic dianhydrides in the presence of metallic salts of octoic acid. The salts, for example stannous octoate, ferric octoate and aluminum octoate, favor the formation of imide linkages at the expense of other possible reactions

    Adjustable high emittance gap filler

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    A flexible, adjustable refractory filler is disclosed for filling gaps between ceramic tiles forming the heat shield of a space shuttle vehicle, to protect its aluminum skin during atmospheric reentry. The easily installed and replaced filler consists essentially of a strip of ceramic cloth coated, at least along both its longitudinal edges with a room temperature vulcanizable silicone rubber compound with a high emittance colored pigment. The filler may have one or more layers as the gap width requires. Preferred materials are basket weave aluminoborosilicate cloth, and a rubber compounded with silicon tetraboride as the emittance agent and finely divided borosilicate glass containing about 7.5% B2O3 as high temperature binder. The filler cloth strip or tape is cut to proper width and length, inserted into the gap, and fastened with previously applied drops of silicone rubber adhesive

    Differences in muscle enzyme profile and metabolic response to fighting in bulls from one to three years old

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    The metabolic response to exercise is partially linked to muscle enzyme profile, and both factors might be influenced by ageing. This research aims: 1) To analyze the differences in muscle characteristics of fighting bulls of different ages; and 2) To assess whether the muscle enzyme profile is affected by ageing in the same way it affects other bovine breeds. Muscle biopsies from gluteus medius and semitendinosus muscles were withdrawn immediately after bullfighting, at depths of 3 and 5 cm, from a total of 24 animals, belonging to three age groups: A (1-year-olds; n=6), B (2-year-olds; n=6) and C (3-year-olds; n=12). Muscle concentrations of glycogen, lactate, adenosin triphosphate and glucose-6-P were determined. In addition, activities of citrate synthase, 3-OH-acyl-dehydrogenase, glycogen phosphorylase, lactate dehydrogenase and hexokinase were measured. No significant differences were found between the two analyzed muscles and neither between depths for any of the muscle parameters. Group A showed lower muscle lactate accumulation, with positive correlations between oxidative and glycolytic enzymes, reflecting a balance between both metabolic pathways. Group B was the most oxidative, whereas group C was the most glycolytic. Therefore, muscle oxidative potential achieved its maximum at 2 years of age, whereas the glycolytic capacity increased progressively with ageing. These results are different from those showed by other bovine breeds, with a progressive reduction in oxidative potential from birth. In conclusion, age significantly influences metabolic response to fighting as well as muscle enzyme profile in bulls

    Association of Tenofovir Use With Risk of Incident Heart Failure in HIV-Infected Patients.

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    BackgroundThe antiretroviral medication, tenofovir disoproxil fumarate (TDF), is used by most human immunodeficiency virus-infected persons in the United States despite higher risks of chronic kidney disease. Although chronic kidney disease is a strong risk factor for heart failure (HF), the association of TDF with incident HF is unclear.Methods and resultsWe identified 21 435 human immunodeficiency virus-infected patients in the United States Veterans Health Administration actively using antiretrovirals between 2002 and 2011. We excluded patients with a prior diagnosis of HF. TDF was analyzed categorically (current, past, or never use) and continuously (per year of use). Proportional hazards regression and fully adjusted marginal structural models were used to determine the association of TDF exposure with risk of incident HF after adjustment for demographic, human immunodeficiency virus-related, and cardiovascular risk factors. During follow-up, 438 incident HF events occurred. Unadjusted 5-year event rates for current, past, and never users of TDF were 0.9 (95%CI 0.7-1.1), 1.7 (1.4-2.2), and 4.5 (3.9-5.0), respectively. In fully adjusted analyses, HF risk was markedly lower in current TDF users (HR=0.68; 95%CI 0.53-0.86) compared with never users. Among current TDF users, each additional year of TDF exposure was associated with a 21% lower risk of incident HF (95%CI: 0.68-0.92). When limited to antiretroviral-naive patients, HF risk remained lower in current TDF users (HR=0.53; 95%CI 0.36-0.78) compared to never users.ConclusionsAmong a large national cohort of human immunodeficiency virus-infected patients, TDF use was strongly associated with lower risk of incident HF. These findings warrant confirmation in other populations, both with TDF and the recently approved tenofovir alafenamide fumarate

    The hidden symbiotic star SU Lyn -- detection of flickering in U band

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    We report photometric observations of the hidden symbiotic star SU Lyn in the optical bands. In five nights we detect a weak flickering in U band with amplitude of about 0.05 magnitudes. No intranight variations are found in B, V, g' and r' bands. This is one more indication that the secondary component is a white dwarf accreting at low accretion rate. We also searched for intranight variability of a dozen related object (RR Boo, RT Boo, AM Cyg, AG Peg, BF Cyg, NQ Gem, StHa190, V627 Cas, XX Oph, FS Cet and Y Gem) in which no variability above the observational errors is detected.This work is part of the project KP-06-H28/2 08.12.2018 ”Binary stars with compact object” (Bulgarian National Science Fund). DM and BB acknowledge project RD-08-100/2022. JM and PLE acknowledge support from Programa Operativo FEDER 2014-2020 and Consejer´ıa de Econom´ıa y Conocimiento of Junta de Andaluc´ıa (Ref. 1380270)

    Proper motions of the HH1 jet

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    We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of 20\sim 20~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in 450\sim 450~yr and at a distance of 80"\sim 80" from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

    Estimating the funding gap of the Pension Benefit Guaranty Corporation

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    Pension Benefit Guaranty Corporation ; Pensions ; Insurance

    Estrategias de búsqueda para la psicología de la competición deportiva en Google académico vs. Medline, Sportdiscus y Psycinfo

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    Searching Strategies in data bases Medline, SportDiscus, Psycinfo and the search engine Google Scholar presents a set of peculiarities in retrieving information about sport competition psychology. We have consulted teachers who teach such item in Departamento de Educación Física de la ULPGC to establish the terminology in Spanish and English. The documents recovered are mostly articles in journals from anglophone area. As the results are more relevant to retrieve such information and a comparison between what recovered from the specialized databases and Google Schola

    Transcriptomics and molecular evolutionary rate analysis of the bladderwort (Utricularia), a carnivorous plant with a minimal genome

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    <p>Abstract</p> <p>Background</p> <p>The carnivorous plant <it>Utricularia gibba </it>(bladderwort) is remarkable in having a minute genome, which at ca. 80 megabases is approximately half that of <it>Arabidopsis</it>. Bladderworts show an incredible diversity of forms surrounding a defined theme: tiny, bladder-like suction traps on terrestrial, epiphytic, or aquatic plants with a diversity of unusual vegetative forms. <it>Utricularia </it>plants, which are rootless, are also anomalous in physiological features (respiration and carbon distribution), and highly enhanced molecular evolutionary rates in chloroplast, mitochondrial and nuclear ribosomal sequences. Despite great interest in the genus, no genomic resources exist for <it>Utricularia</it>, and the substitution rate increase has received limited study.</p> <p>Results</p> <p>Here we describe the sequencing and analysis of the <it>Utricularia gibba </it>transcriptome. Three different organs were surveyed, the traps, the vegetative shoot bodies, and the inflorescence stems. We also examined the bladderwort transcriptome under diverse stress conditions. We detail aspects of functional classification, tissue similarity, nitrogen and phosphorus metabolism, respiration, DNA repair, and detoxification of reactive oxygen species (ROS). Long contigs of plastid and mitochondrial genomes, as well as sequences for 100 individual nuclear genes, were compared with those of other plants to better establish information on molecular evolutionary rates.</p> <p>Conclusion</p> <p>The <it>Utricularia </it>transcriptome provides a detailed genomic window into processes occurring in a carnivorous plant. It contains a deep representation of the complex metabolic pathways that characterize a putative minimal plant genome, permitting its use as a source of genomic information to explore the structural, functional, and evolutionary diversity of the genus. Vegetative shoots and traps are the most similar organs by functional classification of their transcriptome, the traps expressing hydrolytic enzymes for prey digestion that were previously thought to be encoded by bacteria. Supporting physiological data, global gene expression analysis shows that traps significantly over-express genes involved in respiration and that phosphate uptake might occur mainly in traps, whereas nitrogen uptake could in part take place in vegetative parts. Expression of DNA repair and ROS detoxification enzymes may be indicative of a response to increased respiration. Finally, evidence from the bladderwort transcriptome, direct measurement of ROS <it>in situ</it>, and cross-species comparisons of organellar genomes and multiple nuclear genes supports the hypothesis that increased nucleotide substitution rates throughout the plant may be due to the mutagenic action of amplified ROS production.</p
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