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  1. 1

    Diffusivities of linear unsaturated ketones and aldehydes in compressed liquid ethanol

    Publication
    by Zêzere, Bruno
    Other Authors: Buchgeister, Simon; Faria, Sofia Neto; Portugal, Inês; Gomes, José R. B.; Silva, Carlos M.
    For the accurate design, optimization and simulation of chemical processes limited by mass transfer kinetics it is important the knowledge of transport properties, namely, diffusion coefficients, D12. In this work, the D12 values of six unsaturated linear ketones (i.e., propanone, butanone, propan-2-one, propan-3-one, hexan-2-one and hexan-3-one) and three unsaturated linear aldehydes (i.e., butanal, pentanal and hexanal) in (compressed) liquid ethanol were measured at temperatures from 303.15 K to 333.15 K and pressures up to 150 bar. The D12 values of ketones are in the range of 1.28 × 10−5 – 2.89 × 10−5 cm2 s−1 and of the aldehydes are between 1.39 × 10−5 and 2.68 × 10−5 cm2 s−1. The general trends of D12 regarding temperature, pressure, Stokes-Einstein coordinate, and free volume are presented and discussed. The diffusivities of the various ketones position isomers and aldehyde/ketone isomers were statistically compared, being possible to conclude that the former ones exhibit indistinguishable diffusivities while different values appear for aldehydes/ketones isomers. Finally, five models and a machine learning algorithm from the literature were tested to predict/correlate the new data. It is suggested that the TLSM model should be the preferred approach for D12 prediction of linear unsaturated aldehydes and ketones in liquid compressed ethanol.
    2022 article Portugal open access
  2. 2

    Chain extension in electrospun polystyrene fibres: a SANS study

    Publication
    by Mohan, Saeed D.
    Other Authors: Mitchell, Geoffrey; Davis, Fred J.
    Origin: IC-online
    Small angle neutron scattering techniques were used to quantify the size and shape of the chain conformation in electrospun fibres of atactic polystyrene prepared from solutions in methyl ethyl ketone. Aligned arrays of fibres were collected onto a rotating collector with tangential velocity varying between 0 ms-1 and ∼15 ms-1. The measured radii of gyration of the polystyrene chains were found to be slightly higher than that expected for samples prepared from solutions in the concentrated regime. The ratio of the radius of gyration parallel and perpendicular to the chain axis was found to be ∼1.05 in contrast to the substantial macroscopic shape transformation intrinsic to electrospinning. When the tangential velocity of the rotating collector was greater than the flight velocity of the fibres (ca. 4 ms -1), a further extension of the polymer chains was observed with a ratio of the radii of gyration increasing to 1.20 at the highest collector speeds. It is proposed that the heterogeneous processes involved, particularly solvent evaporation and the formation of a polymer skin during electrospinning play a significant role in determining the level of molecular anisotropy in the fibres. © 2011 The Royal Society of Chemistry.
    2011 article Portugal open access
  3. 3

    The swinholide biosynthesis gene cluster from a terrestrial cyanobacterium, Nostoc sp. strain UHCC 0450

    Publication
    by Humisto A.
    Other Authors: Jokela J.; Liu L.; Wahlsten M.; Wang H.; Permi P. et al.
    Swinholides are 42-carbon ring polyketides with a 2-fold axis of symmetry. They are potent cytotoxins that disrupt the actin cytoskeleton. Swinholides were discovered from the marine sponge Theonella sp. and were long suspected to be produced by symbiotic bacteria. Misakinolide, a structural variant of swinholide, was recently demonstrated to be the product of a symbiotic heterotrophic proteobacterium. Here, we report the production of swinholide A by an axenic strain of the terrestrial cyanobacterium Nostoc sp. strain UHCC 0450. We located the 85-kb trans-AT polyketide synthase (PKS) swinholide biosynthesis gene cluster from a draft genome of Nostoc sp. UHCC 0450. The swinholide and misakinolide biosynthesis gene clusters share an almost identical order of catalytic domains, with 85% nucleotide sequence identity, and they group together in phylogenetic analysis. Our results resolve speculation around the true producer of swinholides and demonstrate that bacteria belonging to two distantly related phyla both produce structural variants of the same natural product. In addition, we described a biosynthesis cluster from Anabaena sp. strain UHCC 0451 for the synthesis of the cytotoxic and antifungal scytophycin. All of these biosynthesis gene clusters were closely related to each other and created a group of cytotoxic macrolide compounds produced by trans-AT PKSs of cyanobacteria and proteobacteria. © 2018 American Society for Microbiology.
    2018 article Portugal open access
  4. 4

    Morfometria e metabólitos sanguíneos como medidas de condição corporal para Carollia perspicillata (Chiroptera, Phyllostomidae) em uma área de Mata Atlântica no Nordeste do Brasil...

    Publication
    by Oliveira, Talita Campos
    Origin: Oasisbr
    Changes in Body Condition Index (ICC), blood glucose and ketonemia of Carollia perspicillata (Chiroptera, Phyllostomidae) were observed in an area of Atlantic Forest remnants in northeastern Brazil. The ICC with best performance was chosen through correlations with the forearm length and blood metabolites. The selected ICC was subsequently analyzed with season, age, gender, breeding status, presence of ectoparasites and stool volume. Blood glucose and ketonemia were also correlated with the ICC chosen and the other variables. The results showed that the Simple Reason and Observed Mass ICCs were the best to represent the body condition in this population of C. perspicillata. The ICCs varied significantly with the activity time and the presence of fecal material, and showed no changes from the season, sex, nor the presence of ectoparasites. The concentration of glucose was significantly affected by the capture time and the age of bats, while the ketone showed no significant changes in relation to any of the variables used. C. perspicillata probably inhabits a place with plenty of resources, since the body condition represented by the ICCs and the blood metabolites did not change significantly throughout the year.
  5. 5

    MEDICAL EFFECT OF SPORTS ON IMPROVING THE MAXIMUM OXYGEN

    Publication
    by Yu,Hua
    Origin: Oasisbr
    ABSTRACT Introduction: Maximum oxygen uptake is an effective indicator of the level of human cardiopulmonary function and aerobic work capacity. Observing the effects of aerobic training and formulating scientific training plans are of considerable value. Objective: To observe the effect of physical exercise on the human body's maximum oxygen uptake and arterial blood ketone body ratio. Methods: Before and after 4 weeks of physical exercise, the maximum oxygen uptake, blood lactic acid and heart rate changes, and ketone body content in the incremental load exercise experiment was measured in the human body. Results: The subjects’ maximum oxygen uptake, maximum exercise load, heart rate, and blood lactic acid levels increased significantly after physical exercise. Conclusion: The human body's maximum oxygen uptake is enhanced under sports. Level of evidence II; Therapeutic studies - investigation of treatment results.
    2021 article Brazil open access
  6. 6
  7. 7

    Use of glycerol, waste glycerol from biodiesel production and other protic solvents in bioactive α,β-unsaturated ketones synthesis

    Publication
    by Torrezan, Guilherme Silva
    Other Authors: Polaquini, Carlos Roberto; Lima, Marcelo Freitas; Regasini, Luis Octavio
    Origin: Oasisbr
    Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
    2020 article Brazil open access
  8. 8

    The sexual behaviour of Chagas' disease vectors: chemical signals mediating communication between male and female triatomine bugs

    Publication
    by Manrique, Gabriel
    Other Authors: Lorenzo, Marcelo Gustavo
    Origin: Oasisbr
    Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Fisiología de Insectos. Buenos Aires, Argentina
    2014 article Brazil open access
  9. 9

    Síntese de (5-trifluormetil-1H-pirazol-1-IL)(quinolin-4-IL)metanonas de interesse farmacológico

    Publication
    by Nogara, Pablo Andrei
    Origin: Oasisbr
    Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
    2017 master thesis Brazil open access
  10. 10

    The effect of clay treatment on remediation of diethylketone contaminated wastewater : uptake, equilibrium and kinetic studies

    Publication
    by Quintelas, C.
    Other Authors: Figueiredo, Hugo; Tavares, M. T.
    The ability of four different clays to adsorb diethylketone was investigated in batch experiments aiming to treat wastewater with low solvent concentrations. The adsorption performance in terms of uptake followed the sequence: vermiculite > sepiolite = kaolinite = bentonite, for all the adsorbent doses tested (from 0.1 to 1.5 g) in 150 mL of ketone solution (800 mg/L). The equilibrium data in the batch systems were described by Sips and Dubinin–Raduskevich isotherms. The best fits for bentonite and kaolinite clays were obtained with the Sips isotherm and for sepiolite and vermiculite the best fits were obtained with the Dubinin–Raduskevich model. Kinetic data were described by pseudo-first and pseudo-second order kinetics models. The best fit was obtained for the pseudo-first order model which assumed that the interaction rate was limited only by one process or mechanism on a single class of sorbing sites and that all sites were time dependent. The presence of functional groups on the clay surface that might have interacted with the solvent was confirmed by FTIR. XRD analysis was also performed. This study showed that the tested clays are very effective for the removal of diethylketone from industrial effluents.
    2011 article Portugal open access