1,283 research outputs found

    Models for the 3-D axisymmetric gravitational potential of the Milky Way Galaxy - A detailed modelling of the Galactic disk

    Full text link
    Aims. Galaxy mass models based on simple and analytical functions for the density and potential pairs have been widely proposed in the literature. Disk models constrained by kinematic data alone give information on the global disk structure only very near the Galactic plane. We attempt to circumvent this issue by constructing disk mass models whose three-dimensional structures are constrained by a recent Galactic star counts model in the near-infrared and also by observations of the hydrogen distribution in the disk. Our main aim is to provide models for the gravitational potential of the Galaxy that are fully analytical but also with a more realistic description of the density distribution in the disk component. Methods. From the disk model directly based on the observations (here divided into the thin and thick stellar disks and the HI and H2_2 disks subcomponents), we produce fitted mass models by combining three Miyamoto-Nagai disk profiles of any "model order" (1, 2, or 3) for each disk subcomponent. The Miyamoto-Nagai disks are combined with models for the bulge and "dark halo" components and the total set of parameters is adjusted by observational kinematic constraints. A model which includes a ring density structure in the disk, beyond the solar Galactic radius, is also investigated. Results. The Galactic mass models return very good matches to the imposed observational constraints. In particular, the model with the ring density structure provides a greater contribution of the disk to the rotational support inside the solar circle. The gravitational potential models and their associated force-fields are described in analytically closed forms, and in addition, they are also compatible with our best knowledge of the stellar and gas distributions in the disk component. The gravitational potential models are suited for investigations of orbits in the Galactic disk.Comment: 22 pages, 13 figures, 11 tables, accepted for publication in A&

    An embedded crack model for the simulation of the complex interactions in fibre reinforced concrete

    Get PDF
    There are several benefits of introducing steel fibres in reinforced concrete. They can improve the structural ductility, reduce the permeability, and provide more resistance to cracking caused by loading and shrinkage. Steel fibres are mainly activated when they are crossed by active cracks in what is known by the bridging effect. They are mostly inactive otherwise. With the progress of damage, the fibres can be pulled out or fail, in which case the bond with the cementitious matrix is a critical factor for accurate simulations. Although existing models that are able to simulate fibres as discrete elements can achieve realistic predictions, difficulties are found in the generation of complex meshes with numerous randomly-oriented fibres, namely due to the requirement of excessive degrees of freedom and long computational times. The formulation herein proposed, embeds both discrete fibres and cracks within the finite elements, while accounting for the main features of the fibre behaviour, including the main effects such as the bond between fibre and cementitious material and snubbing. It should be highlighted that the fibre behaviour is modelled without the need for additional degrees of freedom. An advanced constitutive behaviour law is implemented that accounts for the changes depending on the inclination angle of the fibre relative to the crack and its embedment length. For fracture simulation, the model uses the Discrete Strong Discontinuous Approach (DSDA), where the jumps related to the opening of the cracks are transmitted to the parent element as a rigid body motion. Several numerical tests are used to assess the performance of the numerical technique, which include comparison with other formulations and experimental data

    Biochemical changes in hybrid pumpkin seeds at different stages of maturation.

    Get PDF
    O presente estudo teve como objetivo avaliar alterações bioquímicas em sementes do híbrido de abóbora ?Jabras?, oriundas de frutos colhidos em diferentes estádios de maturação (15; 30; 45; 60 e 75 dias após a antese), sendo que, em cada época, foram colhidos trinta frutos: quinze frutos tiveram suas sementes extraídas imediatamente e os outros quinze foram armazenados por vinte dias em caixas plásticas e, somente após esse período, tiveram suas sementes extraídas. Após o beneficiamento e secagem das sementes, foram realizadas as seguintes determinações: grau de umidade, germinação, primeira contagem e atividade de enzimas antioxidantes (peroxidase, ascorbato peroxidase, catalase e superóxido dismutase). Sementes provenientes de frutos colhidos até 30 DAA apresentaram baixa germinação e vigor e elevada atividade de enzimas antioxidantes, demonstrando que as mesmas encontravam-se imaturas e que a secagem possivelmente, provocou danos ao sistema de membranas celulares. O resultado obtido neste estudo demonstrou que a análise relacionada às alterações na atividade de enzimas durante o desenvolvimento e maturação das sementes foi eficiente para avaliar as alterações fisiológicas e bioquímicas em sementes de abóbora, cultivar ?Jabras?

    Removal of Paracetamol and Cu2+ from Water by Using Porous Carbons Derived from Agrowastes

    Get PDF
    Publisher Copyright: © 2023 by the authors.Dende and babassu coconuts are largely used in tropical countries, namely in Brazil, for the extraction of oils from kernels. The remaining biowastes are industrially processed to produce porous carbons (PCs). PCs derived from dende and babassu biowastes and produced at an industrial scale have been characterized by textural, chemical, and ecotoxicological parameters. A commercial activated carbon (CC) of mineral origin has been used as a benchmarking material. Although the CC sample presented a higher surface area (SBET = 1083 m2/g), the PCs derived from the biowastes were richer in micropores (Vmicro = 0.25–0.26 cm3/g), while the CC carbon presented wider pore size distribution with a higher mesopore volume (Vmeso = 0.41 cm3/g). All the adsorbents used in this work have shown a non-acute ecotoxic behavior for the bacterium Vibrio fischeri (EC50-30 min > 99% v/v). The adsorbents have been tested for paracetamol and Cu2+ adsorption in mono- and bicomponent solutions. The uptake capacities of paracetamol (qe, 98–123 mg g−1) and Cu2+ (qe, 15–18 mg g−1) from monocomponent solutions were similar to the ones obtained in the bicomponent solutions, indicating no competition or cooperative effects but a site-specific adsorption. This finding represents an advantage for the removal of these adsorbates when present in the same solution as they can be adsorbed under similar rates as in the single systems. Paracetamol adsorption was related to micropore filling, π-π interactions, and H-bonding, whereas Cu2+ removal was attributed to the cation exchange mechanism and complexation to the hydroxyl groups at the carbons’ surface.publishersversionpublishe

    QTLs for resistance to soybean cyst nematode, races 3, 9, and 14 in cultivar Hartwig.

    Get PDF
    The objective of this work was to identify major and minor?effect quantitative trait loci (QTL) for resistance to races 3, 9, and 14 of soybean cyst nematode (SCN) in Hartwig cultivar; to map new resistance QTLs for these races; and to check for the existence of epistatic interactions between QTLs. Cultivar Hartwig is an important resistance source to SCN. Recombinant inbred lines (RIL) obtained from a cross between 'Hartwig' (resistant) and Y23 (susceptible) were evaluated regarding resistance to the three races. New genomic regions for resistance to SCN were identified by microsatellites. Four QTLs, which explained between 12 and 34% of phenotypic variance, were detected for resistance to race 3 in linkage groups (LG) A2, G, J, and M. The QTL in LG G is also important for resistance to race 9. Epistatic interactions were detected between loci, which indicate resistance to races 9 and 14. There are high and low? effect resistance QTLs to SCN. QTLs de resistência ao nematoide do cisto da soja, raças 3, 9 e 14 na cultivar Hartwig: O objetivo deste trabalho foi identificar locos associados a características quantitativas (QTL) de efeito maior e menor para a resistência às raças 3, 9 e 14 do nematoide do cisto da soja (NCS) na cultivar Hartwig, mapear novos QTLs de resistência para estas raças e verificar a existência de interações epistáticas entre QTLs. A cultivar Hartwig é uma importante fonte de resistência ao NCS. Linhagens endogâmicas recombinantes (LER) obtidas do cruzamento entre 'Hartwig' (resistente) e Y23 (suscetível) foram avaliadas quanto à resistência às três raças. Novas regiões genômicas de resistência ao NCS foram identificadas por microssatélites. Quatro QTLs, que explicaram entre 12 e 34% da variância fenotípica, foram detectados para a resistência à raça 3 nos grupos de ligação (GL) A2, G, J e M. O QTL no GL G também é importante para a resistência à raça 9. Interações epistáticas foram detectadas entre loci, o que indica resistência às raças 9 e 14. Há QTLs de maior e menor efeito para a resistência ao NCS

    Dynamic blockage of drippers as a function of the application of super simple phosphate and nítric acid in localized irrigation

    Get PDF
    O superfosfato simples (SS) é uma alternativa aos adubos fosfatados que são utilizados via fertirrigação, como o ácido fosfórico, que provoca acidificação do bulbo úmido no solo, e o monofosfato de amônio purificado, que apresenta maior preço. No entanto, não se conhece o efeito de tal adubo no funcionamento de emissores, principalmente nos gotejadores, nem se é possível controlar o entupimento por SS por meio de aplicações de ácido. Assim, desenvolveu-se este trabalho com o objetivo de avaliar a possibilidade da utilização do superfosfato simples via gotejamento, como alternativa ao uso de outros adubos fosfatados, e a tentativa de controle do entupimento utilizando ácido nítrico. O trabalho foi desenvolvido em bancada de ensaios de gotejadores, localizada no Laboratório de Hidráulica da ESALQ/USP. Foram aplicadas doses de 50; 75 e 100% da solubilidade do superfosfato simples (SS), em 26 tubogotejadores de diferentes marcas comerciais, e ao fim de 360 horas de irrigação, foi aplicado ácido nítrico com pH 2, na tentativa de desentupir os gotejadores mais sensíveis. Diante dos resultados, foi possível inferir que o uso do superfosfato simples pode ser feito via fertirrigação, e o ácido nítrico, aplicado segundo esta metodologia, não proporcionou a desobstrução dos emissores.The super simple phosphate (SS) is an alternative to the phosphorous fertilizers which are used through fertigation, as the phosphoric acid, which triggers acidification of the wetted volume in the soil, and the monophosfato of purified ammonium, that has a higher price. However, the effect of such fertilizer in the emitters function, mainly in the drippers, is not known neither if it is possible to control the blockage for SS through acid applications. Thus, this study was developed in order to evaluate the possibility of the use of super simple phosphate trough drip irrigation, as an alternative to the use of other phosphorous fertilizers, and the attempt of controlling the blockage with nitric acid. The work was carried out in bench of drippers rehearsals, located at the Hydraulic laboratory in ESALQ-USP. Doses of 50; 75 and 100% of the super simple phosphate (SS) were applied in 26 emitter tubes with different commercial marks, and after 360 hours the nitric acid with a pH of 2 was applied, in the attempt of clearing the most sensitive drippers to the blockage. With the results it was possible to infer that: the use of super simple phosphate can be done by fertigation without causing damages to the system and the nitric acid, applied according to this methodology, did not provide the clearance of the emitters

    Protein transport into peroxisomes: Knowns and unknowns

    Get PDF
    Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and rapidly transported into the organelle by a complex machinery. The data gathered in recent years suggest that this machinery operates through a syringe-like mechanism, in which the shuttling receptor PEX5 - the “plunger” - pushes a newly synthesized protein all the way through a peroxisomal transmembrane protein complex - the “barrel” - into the matrix of the organelle. Notably, insertion of cargo-loaded receptor into the “barrel” is an ATP-independent process, whereas extraction of the receptor back into the cytosol requires its monoubiquitination and the action of ATP-dependent mechanoenzymes. Here, we review the main data behind this model.We would like to thank Dr. Marc Fransen (KU Leuven) for his critical reading of the manuscript. This work was financed by FEDER - Fundo Europeu de Desenvolvimento Regional, funds through the COMPETE 2020 - Operacional Programme for Competitiveness and Internationalization (POCI), Portugal 2020, and by Portuguese funds through FCT - Fundação para a Ciência e a Tecnologia/Ministerio da Ciência, Tecnologia e Inovação in the framework of the projects “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274) and “Themolecular mechanisms of peroxisome biogenesis” (PTDC/BEX-BCM/2311/2014), and through Norte 2020–Programa Operacional Regional do Norte, under the application of the “Porto Neurosciences and Neurologic Disease Research Initiative at i3S (NORTE-01-0145-FEDER-000008).” T.F., T.A.R., A.F.D., A.B.B., and D.B. were supported by Fundação para a Ciência e a Tecnologia, Programa Operacional Potencial Humano do QREN and Fundo Social Europeu

    Seasonal variation of bioactive properties and phenolic composition of Cynara cardunculus var. altilis

    Get PDF
    Cynara cardunculus L. (cardoon) has several health benefits mainly attributed to its abundance in polyphenols. In this study, cardoon heads (capitula) were harvested in Greece during the flowering stage, and the hydroethanolic extracts were assessed in terms of phenolic compounds composition and antioxidant, cytotoxic, anti-inflammatory, and antimicrobial activities. The phenolic profile was evaluated by HPLC-DAD-ESI/MS to better understand the seasonal changes in the individual compound levels and how these changes correlate with bioactive properties. The main phenolic compounds identified were caffeoylquinic and dicaffeoylquinic acid derivatives. Immature heads (Car A: principal growth stage (PGS) 5) had the highest phenolic content (34.3 mg/ g) and cytotoxic (GI50 of 69–268 μg/mL) and anti-inflammatory (IC50 of 183 μg/mL) activities. Sample Car D (PGS 6/7) revealed the highest antioxidant (IC50 of 23–227 μg/mL) and antifungal (MIC of 0.26–0.51 mg/mL) potential. Regarding the antibacterial activity, Car E (PGS 7) revealed the best results (MIC of 0.59–1.18 mg/ mL). This study suggests that the maturity stage of the plant influences the phenolic composition and bioactivity.info:eu-repo/semantics/publishedVersio
    corecore