178 research outputs found

    Characteristics of large-scale and superstructure motions in a turbulent boundary layer overlying complex roughness

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    The structural attributes of turbulent flow over a complex roughness topography are explored using high-frame-rate stereo particle-image velocimetry measurements in the wall-normal–spanwise plane. The roughness under consideration was replicated from a turbine blade damaged by deposition of foreign materials and contains a broad range of topographical scales arranged in a highly irregular manner. Previous results from Barros and Christensen [Observations of turbulent secondary flows in a rough-wall boundary layer. J Fluid Mech. 2014;748] revealed strong spanwise heterogeneity in the flow attributed to the formation of roughness-induced turbulent secondary flows identified by spanwise-alternating low- and high-momentum flow pathways (HMP & LMP, respectively) in the mean flow marked by enhanced Reynolds stresses and turbulent kinetic energy. Frequency spectra of streamwise velocity at fixed wall-normal location presented herein also display strong dependence on spanwise position. In particular, the roughness promotes enhanced energy content of the large-scale and smaller-scale motions (as opposed to very-large-scale ones). Depending on spanwise position, pre-multiplied spectra highlight significant modification of the energy content of the very large-scale motions (superstructures) due to roughness compared to smooth-wall flow. Of note, a shift in both TKE and RSS content to shorter streamwise scales at an LMP was noted, while less of an impact was found coincident with an HMP

    Measurements of skin-friction of systematically generated surface roughness

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    The flow conditions at which a given surface will begin to show the effects of roughness in the form of increased wall shear stress above that of the hydraulically-smooth wall and the behavior of frictional drag in the transitionally-rough regime are still poorly understood. From a practical standpoint, the engineering correlations to predict this behavior should be based on information that can be obtained solely from the surface topography, thus excluding any information that requires hydrodynamic testing. The goal of this work is to take a systematic approach when generating surface roughness where the roughness parameters can be controlled. Three surfaces with fixed amplitude and varying power-law spectral slope (E(κ) ∼ κP; P = -0.5, -1.0, -1.5) were generated and replicated using high-resolution 3D printing. Results show that the surface with the shallower spectral slope, P = -0.5, produces the highest drag, whereas the surface with the steeper spectral slope, P = -1.0, produces the least drag. This highlights that some roughness scales do not contribute significantly to the drag. In fact, the effective slopes, ES of the investigated surfaces were less than 0.35, which indicates that the surfaces are in the so-called “wavy” regime (Schultz and Flack, 2009). A high-pass filter of 1 mm (corresponding to  ∼ 10 times of the roughness height) was applied. By removing the long-wavelength roughness scales, the correlation between the filtered roughness amplitude and the frictional drag showed the correct trend

    Energy use optimization in ventilation of operating rooms during inactivity periods

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    Producción CientíficaHospitals are highly energy demanding buildings, where simple actuations can involve large savings. However, energy efficiency actions must comply with the high safety standards. Operating rooms demand continuous ventilation despite the short activity periods. Setback during non-occupation of the operating rooms can reduce ventilation loads but must not hinder indoor overpressure to avoid infiltrations. Besides, it prevents any existing heat recovery system from operation. This work evaluates setback ventilation in operating rooms at a case study in Spain, from two approaches: its effect on indoor overpressure and its preference to an existing coil heat recovery (runaround) loop. It bases on monitored data of two operating rooms under setback and normal ventilation with operation of the heat recovery system. Seven tests are performed throughout the year, whose comparison to estimated results enables extrapolation to yearly operation. Results show that indoor overpressure maintain at 15 Pa under setback, thus meeting current and coming standards. Setback turned to be always preferable to hear recovery under cooling needs. Estimated heating and electric yearly supply energy savings reach 29 MWht and 262 MWhe, the latter accounting for 2% of the total electric energy consumption of the hospital during 2019.Junta de Castilla y León (grant EREN_2019_L2_UVA

    Brazilian consensus meeting on stem cell transplantation: hemoglobinopathies comittee

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    Os distúrbios hereditários das hemoglobinas são as doenças genéticas mais frequentes do homem e mais difundidas no mundo, abrangendo sobretudo continentes como África, Américas, Europa e extensas regiões da Ásia. Estima-se que haja 270 milhões de portadores de hemoglobinopatias no mundo, dos quais 80 milhões são portadores de talassemia. Aproximadamente 60 mil crianças nascem anualmente no mundo com talassemia e 250 mil com anemia falciforme, dando uma frequência de 2,4 crianças afetadas para cada 1.000 nascimentos. No Brasil, a doenca falciforme é a doença hereditária monogênica mais comum, estimando-se que haja entre 20 a 30 mil pacientes portadores desta doenca. O transplante de células-tronco hematopoéticas alogênico (TCTH alo) é atualmente a única modalidade terapêutica capaz de curar pacientes com hemoglobinopatias. Neste artigo discutiremos os dados disponíveis na literatura e sugerimos os critérios para a indicação do TCTH nas hemoglobinopatias.Hemoglobinopathies are the most prevalent genetic diseases in man. Most cases are described in Europe, Africa and in the Americas. About 270 million hemoglobinopathy carriers are alive today with 80 million being carriers of thalassemia. We estimate that, throughout the world, about 60,000 children are born annually with thalassemia and 250,000 with sickle cell disease with an estimated frequency of 2.4 children in every 1000 births. Sickle cell disease is the most common monogenic hereditary disease in Brazil with a total of from 20,000 to 30,000 patients. Allogeneic stem cell transplantation is the only curative approach. Here we describe published data and propose criteria to indicate stem cell transplantation in thalassemia and sickle cell disease patients

    Bradykinin B2 Receptors of Dendritic Cells, Acting as Sensors of Kinins Proteolytically Released by Trypanosoma cruzi, Are Critical for the Development of Protective Type-1 Responses

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    Although the concept that dendritic cells (DCs) recognize pathogens through the engagement of Toll-like receptors is widely accepted, we recently suggested that immature DCs might sense kinin-releasing strains of Trypanosoma cruzi through the triggering of G-protein-coupled bradykinin B2 receptors (B2R). Here we report that C57BL/6.B2R−/− mice infected intraperitoneally with T. cruzi display higher parasitemia and mortality rates as compared to B2R+/+ mice. qRT-PCR revealed a 5-fold increase in T. cruzi DNA (14 d post-infection [p.i.]) in B2R−/− heart, while spleen parasitism was negligible in both mice strains. Analysis of recall responses (14 d p.i.) showed high and comparable frequencies of IFN-γ-producing CD4+ and CD8+ T cells in the spleen of B2R−/− and wild-type mice. However, production of IFN-γ by effector T cells isolated from B2R−/− heart was significantly reduced as compared with wild-type mice. As the infection continued, wild-type mice presented IFN-γ-producing (CD4+CD44+ and CD8+CD44+) T cells both in the spleen and heart while B2R−/− mice showed negligible frequencies of such activated T cells. Furthermore, the collapse of type-1 immune responses in B2R−/− mice was linked to upregulated secretion of IL-17 and TNF-α by antigen-responsive CD4+ T cells. In vitro analysis of tissue culture trypomastigote interaction with splenic CD11c+ DCs indicated that DC maturation (IL-12, CD40, and CD86) is controlled by the kinin/B2R pathway. Further, systemic injection of trypomastigotes induced IL-12 production by CD11c+ DCs isolated from B2R+/+ spleen, but not by DCs from B2R−/− mice. Notably, adoptive transfer of B2R+/+ CD11c+ DCs (intravenously) into B2R−/− mice rendered them resistant to acute challenge, rescued development of type-1 immunity, and repressed TH17 responses. Collectively, our results demonstrate that activation of B2R, a DC sensor of endogenous maturation signals, is critically required for development of acquired resistance to T. cruzi infection

    Development of a composite prototype with GFRP profiles and sandwich panels used as a floor module of an emergency house

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    A series of experimental tests carried out on a composite prototype to be used as a floor module of an emergency house is presented in this paper. The prototype comprises a frame structure formed by GFRP pultruded profiles, and two sandwich panels constituted by GFRP skins and a polyurethane foam core that configures the floor slab. The present work is part of the project “ClickHouse – Development of a prefabricated emergency house prototype made of composites materials” and investigates the feasibility of the assemblage process of the prototype and performance to support load conditions typical of residential houses. Furthermore, sandwich panels are also independently tested, analysing their flexural response, failure mechanisms and creep behaviour. Obtained results confirm the good performance of the prototype to be used as floor module of an emergency housing, with a good mechanical behaviour and the capacity of being transported to the disaster areas in the form of various low weight segments, and rapidly installed. Additionally, finite element simulations were carried out to assess the stress distributions in the prototype components and to evaluate the global behaviour and load transfer mechanism of the connections.Quadro de Referência Estratégica Nacional (QREN)FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and the Portuguese National Agency of Innovation (ADI) - project no. 3896

    Risk factors for non-diabetic renal disease in diabetic patients

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    Background. Diabetic patients with kidney disease have a high prevalence of non-diabetic renal disease (NDRD). Renal and patient survival regarding the diagnosis of diabetic nephropathy (DN) or NDRD have not been widely studied. The aim of our study is to evaluate the prevalence of NDRD in patients with diabetes and to determine the capacity of clinical and analytical data in the prediction of NDRD. In addition, we will study renal and patient prognosis according to the renal biopsy findings in patients with diabetes. Methods. Retrospective multicentre observational study of renal biopsies performed in patients with diabetes from 2002 to 2014. Results. In total, 832 patients were included: 621 men (74.6%), mean age of 61.7 6 12.8 years, creatinine was 2.8 6 2.2 mg/dL and proteinuria 2.7 (interquartile range: 1.2–5.4) g/24 h. About 39.5% (n ¼ 329) of patients had DN, 49.6% (n ¼ 413) NDRD and 10.8% (n ¼ 90) mixed forms. The most frequent NDRD was nephroangiosclerosis (NAS) (n ¼ 87, 9.3%). In the multivariate logistic regression analysis, older age [odds ratio (OR) ¼ 1.03, 95% CI: 1.02–1.05, P < 0.001], microhaematuria (OR ¼ 1.51, 95% CI: 1.03–2.21, P ¼ 0.033) and absence of diabetic retinopathy (DR) (OR ¼ 0.28, 95% CI: 0.19–0.42, P < 0.001) were independently associated with NDRD. Kaplan–Meier analysis showed that patients with DN or mixed forms presented worse renal prognosis than NDRD (P < 0.001) and higher mortality (P ¼ 0.029). In multivariate Cox analyses, older age (P < 0.001), higher serum creatinine (P < 0.001), higher proteinuria (P < 0.001), DR (P ¼ 0.007) and DN (P < 0.001) were independent risk factors for renal replacement therapy. In addition, older age (P < 0.001), peripheral vascular disease (P ¼ 0.002), higher creatinine (P ¼ 0.01) and DN (P ¼ 0.015) were independent risk factors for mortality. Conclusions. The most frequent cause of NDRD is NAS. Elderly patients with microhaematuria and the absence of DR are the ones at risk for NDRD. Patients with DN presented worse renal prognosis and higher mortality than those with NDRD. These results suggest that in some patients with diabetes, kidney biopsy may be useful for an accurate renal diagnosis and subsequently treatment and prognosis
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