1,209 research outputs found

    The origin ofhigh hydraulic resistance for filter cakes ofdef ormable particles: cell-bed deformation or surface-layer effect?

    Get PDF
    This study reports a numerical approach for modeling the hydraulic resistance ofa filter cake ofdef ormable cells. First, a mechanical and osmotic model that describes the volume fraction ofsolids in a bed ofyeast cells as a function ofthe compressive pressure it experiences is presented. The effects ofpressure on the compressibility ofyeast cells beds were further investigated both by filtration experiments and by centrifugal experiments based on the multiple speed equilibrium sediment height technique. When comparing the latter measurements with compression model calculations, we observed that the method based on centrifugal experiments suffers from rapid relaxation of the compressed bed. Concerning the filtration experiments, specific resistance ofwell-defined bed ofcells were calculated by a combination of the compression model with a formulation for hydraulic resistivity developed using the Lattice Boltzmann method. We further explain the experimental values observed for the hydraulic resistance ofcell beds, assuming that the first layer ofcells in contact with the membrane partially blocks the membrane area open to flow. In such a case, the blocked area seems to be a constant fraction of the normal cell–cell contact area

    New data on the lithostratigraphy of Beiras Group (Schist Greywacke Complex) in the region of Góis-Arganil-Pampilhosa da Serra (Central Portugal)

    Get PDF
    [Abstract] In the course of geological surveys conducted in the region of Góis (Central Portugal) a new unit was recognized at the top of Boque-Serpins Formation, characterized by the presence of levels of quartzites interlayered with shales, now called by Colmeal Formation. Its formal characterization is now presented and their regional geological implications are discussed in the context of the Neoproterozoic metasedimentary sequence of Beiras Group (Dúrico-Beirão Supergroup or “Schist –Greywacke Complex”). The geological surveys in progress confirm that the sequence, from the base to the top, of the Caneiro, Boque-Serpins and Colmeal Formations, feature the same structural and deformation pattern, common to the three units. It is noted that these units, defined in sector south of Coimbra – Lousã - Góis, have wide regional cartographic representation, as they have already been mapped and recognizable from Arganil until Sertã, to the south. To the west, they shall extend to the limit with Ossa-Morena Zone metasediments established by Porto-Tomar dextral wrench fault

    Variscan shear zones and control of Sn-W, Au, U mineralizations in the Central-Iberian Zone in Portugal

    Get PDF
    [Resumo] Propoese urna síntese sobre a génese dos cisalhamentos regionais e estruturas secundárias associadas nas diferentes fases colisionais, para o sector restricto da Zona Centro-Ibérica (Z.C.!.) da orogenia hercínica. Adoptam-se os conceitos de RAMSAY (1980) e SANDERSON &MARCHINI (1984) para enquadrar, respectivamente, a tipologia e cinemática destes cisalhamentos. Esboçase um cenário geral da geometria e cinemática das estructuras na Z.C.!., concomitantemente, com a evolu~ao dos cisalhamentos tangenciais nas fases precocese com os cisalhamentos transcorrentes nas fases tardias do orógeno. No quadro da associa~ao espacial das mineralizag:>es de Sn-W, Au e U aos cisalhamentos, define-se o controlo estrutural destas mineraliza~oes e procede-se a tentativa de hierarquizar as referidas mineralizag:>es da Z.C.!., conectando-as as diferentes fases de deformaçao da orogenia hercínica[Abstract] The tipology and kinematic evolution of the shear zones and related secondary structures in the Central Iberian Zone (Variscan orogeny) are stablished on the basis of the concepts expressed, respectively, by RAMSAY (1980) and SANDERSON & MARCHINI (1984). The geometry and kinematics of these structures are linked to the evolution of nappes in the preliminary deformation phases and with transcurrent shearing in the later deformation phases. The structural control and the spatial relationship of Sn-W, Au and U mineralizations by these shears, is defined. For each her cynian deformations phase it is made an atempt of hierarchyzation of these C.I.Z. mineralizations

    Geological raw materials from a mesolithic archaeological site in NW Portugal

    Get PDF
    This is an author’s version (C. Alves) and not the final published text. The final published text can be found in: Proceedings 2019, 24(1), 10; https://doi.org/10.3390/IECG2019-06222The present work concerns the study of geological raw materials obtained from an excavation site located in Serra da Cabreira (NW Portugal). The majority of the artifacts are made in quartz varieties (with minor occurrences of flint). Milky quartz is dominant, being similar to diverse occurrences of quartz veins in the immediate neighborhood. There are diverse other quartz varieties, indicating the possibility of locations farther away from the shelter. The study of geological raw materials can be seen as an important source of archaeological information, illustrating the evolution of past relationships between humans and geological resources, and also providing relevant information for the present and future, considering namely the extremely low environmental impact of the processing of raw materialsThe first author (Pedro Xavier) would like to thank the Fundação para a Ciência e a Tecnologia (Foundation for Science and Technology) for the Ph.D. scholarship, reference (SFRH/BD/120806/2016). The Lab2PT—Landscapes, Heritage and Territory laboratory—AUR/04509 is supported by the Portuguese “Fundação para a Ciência e a Tecnologia” (Portuguese funds and where applicable the FEDER co-financing, in the aim of the new partnership agreement PT2020 and COMPETE2020—POCI 010145 FEDER 007528)

    Immune Reconstitution Inflammatory Syndrome: Opening Pandora's Box

    Get PDF
    One of the purposes of antiretroviral therapy (ART) is to restore the immune system. However, it can sometimes lead to an aberrant inflammatory response and paradoxical clinical worsening known as the immune reconstitution inflammatory syndrome (IRIS). We describe a 23-year-old male, HIV1 infected with a rapid progression phenotype, who started ART with TCD4+ of 53 cells/mm(3) (3,3%) and HIV RNA = 890000 copies/mL (6 log). Four weeks later he was admitted to the intensive care unit with severe sepsis. The diagnostic pathway identified progressive multifocal leukoencephalopathy, digestive Kaposi sarcoma, and P. aeruginosa bacteraemia. Five weeks after starting ART, TCD4+ cell count was 259 cells/mm(3) (15%) and HIV RNA = 3500 copies/mL (4 log). He developed respiratory failure and progressed to septic shock and death. Those complications might justify the outcome but its autopsy opened Pandora's box: cerebral and cardiac toxoplasmosis was identified, as well as hemophagocytic syndrome, systemic candidiasis, and Mycobacterium avium complex infection. IRIS remains a concern and eventually a barrier to ART. Male gender, young age, low TCD4 cell count, and high viral load are risk factors. The high prevalence of subclinical opportunistic diseases highlights the need for new strategies to reduce IRIS incidence.info:eu-repo/semantics/publishedVersio

    Sustained-Release Bupropion Overdose: A Case Report

    Get PDF
    Bupropion is an atypical antidepressant with a unique aminoketone structure similar to amphetamines. A narrow therapeutic margin is evident from observational studies that show seizure activity with doses of 400-600 mg or higher. A 38-year old woman took an overdose of 6 grams of bupropion with 110 grams of alcohol. She presented to the Emergency Department with agitation, visual hallucinations and myoclonus of the upper limbs; eyes spontaneously open with isochoric and light reactive pupils with horizontal nystagmus; afebrile, normotensive (121/63 mm Hg) and tachycardic (120 beats/minute). The electrocardiogram revealed a sinus tachycardia with prolonged QT interval (QT/QTc: 0.46/ 0.537) and a QRS complex length in the upper limit of normal. Arterial blood gases revealed metabolic acidosis (pH = 7.16) with increased anion-gap (value=18). She developed mal epilepticus needing thiopental induced coma and Intensive Care Unit (ICU) admission. She suffered prolonged symptoms including seizures before fully recovering. The narrow therapeutic range and the increasing use in the treatment of smoking cessation boosted the number of intentional and unintentional poisoning by this drug. Previous reports of bupropion overdose almost all involve the immediate release formulation. There are some reports of overdose with sustained-release formulation, but there is limited information on its spectrum of toxicity
    corecore