441 research outputs found

    A flexible infrastructure for dynamic power control of electric vehicle battery chargers

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    This paper proposes a Flexible Infrastructure for Dynamic Power Control (FIDPC) of Electric Vehicle (EV) Battery Chargers. This infrastructure dynamically adjusts the EV battery charger current, according to the power demand of the home wherein the vehicle is plugged. An infrastructure was implemented to validate this proposal. Such infrastructure is composed by an EV battery charger and a communication system based on a Radio Frequency interface. The battery charger has nominal power of 3.6 kVA and operates with sinusoidal current and unitary total power factor, while the RF interface provides continuous data flow to the battery charger with information about the home total current consumption (rms value). Experimental tests were performed under realistic conditions to validate the concept behind the proposed FIDPC. These tests served to assess the behavior of the EV battery charger with dynamic power control on a single-phase, 230 V, 16 A, 50 Hz residential electrical installation. The experimental results confirm the quick time response of the FIDPC even when working under heavy home load variations.This work was supported by the Fundacao para a Ciencia e Tecnologia (FCT) through Project PEst-UID/CEC/00319/2013. The work of V. Monteiro was supported by the FCT agency through a doctoral scholarship under Grant SFRH/BD/80155/2011. The review of this paper was coordinated by Dr. D. Cao

    Characterization of silicon photodiodes for diffuse reflectance signal extraction

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    Early detection of gastrointestinal (GI) can cers is one of most important concerns in medical field. Its detection at the earliest stage is crucial to increase the patient survival chances. Optical signals extraction and analysis, specifically diffuse reflectance and intrinsic fluorescence, may impr ove the ability to detect GI dysplasia, once some morphological and biochemical changes on the tissues (related with early cancer progre ssion) can modify these signals’ shape and intensity. The project under th is paper aims to develop a chip - sized spectros copy microsystem for the early detection of GI cancer. This paper presents the characterization of silicon photodiodes (n+/p - epilayer type) fabricated in a standard 0.7 μm CMOS process, with different dimensions. The main goal is to conclude which photodio de must be fabricated for the microsystem implementation, taking into account its capacity to extract the signals in the relevant spectral band (350 nm – 750 nm), not comprising the microsystem dimensions. With this study , it can be conclude d that the suit able photodiodes for the detection of those spectroscopic signals are the ones with 125 × 125 μm 2 or 100 × 100 μm 2 active area , once their quantum efficiency varies between 20% and 55%, approximately, above 450 nm. In spite of the low photodiod es quantum efficiency (lower than 20%) below 450 nm, the viability of using the 100 × 100 μm 2 photodiode to extract the diffuse reflectance signal, between 350 nm and 750 nm, was proven using a test phantom representative of a GI tissue.This work is funded by FEDER funds through the "Eixo I do Programa Operacional Fatores de Competitividade (POFC) QREN, projects reference COMPETE: FCOMP-01-0124-FEDER-020241 and FCOMP-01-124-FEDER-037291 (PEst-C/FIS/UI0607/2013) and by FCT – Fundação para a Ciência e a Tecnologia, project reference PTDC/EBB-EBI/120334/2010. S. Pimenta thanks the FCT for the SFRH/BD/87605/2012 PhD grant

    RVG29-Functionalized Lipid Nanoparticles for Quercetin Brain Delivery and Alzheimers Disease

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    Purpose: Lipid nanoparticles (SLN and NLC) were functionalized with the RVG29 peptide in order to target the brain and increase the neuronal uptake through the nicotinic acetylcholine receptors. These nanosystems were loaded with quercetin to take advantage of its neuroprotective properties mainly for Alzheimer's disease. Methods: The functionalization of nanoparticles with RVG29 peptide was confirmed by NMR and FTIR. Their morphology was assessed by transmission electron microscopy and nanoparticles size, polydispersity and zeta potential were determined by dynamic light scattering. The in vitro validation tests were conducted in hCMEC/D3 cells, a human blood-brain barrier model and thioflavin T binding assay was conducted to assess the process of amyloid-beta peptide fibrillation typical of Alzheimer's disease. Results: RVG29-nanoparticles displayed spherical morphology and size below 250 nm, which is compatible with brain applications. Zeta potential values were between −20 and −25 mV. Quercetin entrapment efficiency was generally higher than 80% and NLC nanoparticles were able to encapsulate up to 90%. The LDH assay showed that there is no cytotoxicity in hCMEC/D3 cell line and RVG29-nanoparticles clearly increased in 1.5-fold the permeability across the in vitro model of blood-brain barrier after 4 h of incubation compared with non-functionalized nanoparticles. Finally, this nanosystem was capable of inhibiting amyloid-beta aggregation in thioflavin T binding assay, suggesting its great potential for neuroprotection. Conclusions: RVG29-nanoparticles that simultaneously target the blood-brain barrier and induce neurons protection against amyloid-beta fibrillation proved to be an efficient way of quercetin delivery and a promising strategy for future approaches in Alzheimer's disease. [Figure not available: see fulltext.]. (c) 2020, Springer Science+Business Media, LLC, part of Springer Nature

    GEOMETRICAL OPTIMIZATION OF MIXED CONVECTIVE FLOWS OVER TRIANGULAR ARRANGEMENT OF CYLINDERS

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    The present study consists on the numerical evaluation of a triangular arrangement of circular cylinders submitted to transient, two-dimensional, incompressible, laminar and mixed convective flows. The geometrical evaluation is performed by means of Constructal Design. For all simulations it is considered Reynolds and Prandtl numbers of ReD = 100 and Pr = 0.71. Moreover, three different values of Richardson number are investigated: Ri = 0.1 (which represents flows dominated by forced convective), 1.0 (which represents an equilibrium between forced and natural driven forces) and 10.0 (which represents flows with dominance of natural convective). The conservation equations of mass, momentum and energy are solved with the use of Finite Volume Method (FVM). The buoyancy forces are tackled with the Boussinesq approximation. The area occupied by the triangular arrangement of cylinders is a geometric constraint of the problem and the cylinders have the same diameter. The main purpose is to evaluate the effect of Richardson number over the drag coefficient (CD) and Nusselt number (NuD) between the cylinders and the surrounding flow, as well as, over the optimal ratio ST/D (ratio between transversal pitch and the cylinder) for two different values of the ratio SL/D = 1.5 and 2.5 (ratio between longitudinal pitch and the cylinders diameter). Results showed that the effect of ST/D over drag coefficient and Nusselt number is strongly affected by the magnitude of Richardson number. Concerning the Nusselt number, for Ri = 0.1 the optimal geometry which maximizes the NuD is reached for the highest magnitude of ST/D, while for Ri = 10.0 an intermediate optimal ratio of ST/D maximizes the NuD. The Richardson magnitudes also have large influence over the fluid dynamic and thermal behavior of fluid flow for all evaluated geometries. An increase in the ratio SL/D improved the heat exchange of the flow, but decreased the fluid dynamic performance

    Avaliação das concentrações pré-industriais e actuais de ozono superficial através de séries temporais

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    A importância do estudo das concentrações de ozono superficial está relacionada com os seusefeitos nocivos quando se atingem níveis elevados deste poluente.Do ozono existente actualmente na troposfera, apenas 20% se deve à intrusão estratosférica,resultando os restantes 80% da formação fotoquímica. No entanto, quando as emissõesantropogénicas ainda não afectavam a qualidade do ar, o ozono troposférico tinha origemfundamentalmente no transporte a partir da estratosfera. Assim, a análise no período pré-industrial, quando a formação fotoquímica era insignificante, fornece informações importantessobre a contribuição da actividade humana no aumento das concentrações superficiais de ozono.Com o objectivo de avaliar essa contribuição na área do Porto, foram comparadas concentraçõesem duas épocas com emissões atmosféricas completamente distintas: um período recente (2002-2003) e um período anterior ao desenvolvimento industrial da região (1861-1897). Foramestudadas as correlações mensais entre a concentração de ozono e a humidade relativa, na erapré-industrial. Foram comparadas as evoluções sazonais e as médias anuais dos dois períodosestudados e avaliados os impactes na saúde comparando as concentrações com os limiareslegislados. A análise comparativa das séries temporais das concentrações de ozono e dastemperaturas máxima e mínima, velocidade do vento e precipitação, permitiu a identificação deciclos de concentrações que foram relacionados com a actividade humana em cada um dosperíodos.Os resultados obtidos permitem concluir que as concentrações superficiais de ozono têm sofridoum elevado aumento desde a era pré-industrial, tendo-se observado um aumento de 250% nomês de Maio. A análise de séries pré-industriais revelou que os ciclos existentes são sazonaisexcluindo a influência das actividades humanas. No período recente, os ciclos de 8 hencontrados nas concentrações de ozono, provam a grande influência dos factoresantropogénicos, sendo os factores meteorológicos responsáveis pelos ciclos de 12 h e 24 hidentificados

    The Impact of Ischemia Assessed by Magnetic Resonance on Functional, Arrhythmic, and Imaging Features of Hypertrophic Cardiomyopathy

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    Aims: The aim of the study is to investigate the association between the degree of ischemia due to coronary microvascular dysfunction (CMD) and the left ventricular (LV) tissue characteristics, systolic performance, and clinical manifestations in hypertrophic cardiomyopathy (HCM). Methods and Results: This prospective study enrolled 75 patients with HCM without obstructive epicardial coronary artery disease. Each patient underwent cardiovascular magnetic resonance (CMR) including parametric mapping, perfusion imaging during regadenoson-induced hyperemia, late gadolinium enhancement (LGE) and three-dimensional longitudinal, circumferential, and radial strains analysis. Electrocardiogram, 24-h Holter recording, and cardiopulmonary exercise testing (CPET) were performed to assess arrhythmias and functional capacity. In total, 47 (63%) patients were men with the mean age of 54.6 (14.8) years, 51 (68%) patients had non-obstructive HCM, maximum wall thickness (MWT) was 20.2 (4.6) mm, LV ejection fraction (LVEF) was 71.6 (8.3%), and ischemic burden was 22.5 (16.9%) of LV. Greater MWT was associated with the severity of ischemia (β-estimate:1.353, 95% CI:0.182; 2.523, p = 0.024). Ischemic burden was strongly associated with higher values of native T1 (β-estimate:9.018, 95% CI:4.721; 13.315, p 15% (AUC 0.766, sensitivity 0.724, specificity 0.659). Ischemia was also associated with atrial fibrillation or flutter (AF/AFL) (OR-estimate:1.481, 95% CI:1.020; 2.152, p = 0.039), but no association was seen for non-sustained ventricular tachycardia. Ischemia was associated with shorter time to anaerobic threshold (β-estimate: -0.442, 95% CI: -0.860; -0.023, p = 0.039). Conclusion: In HCM, ischemia associates with morphological markers of severity of disease, fibrosis, arrhythmia, and functional capacity.info:eu-repo/semantics/publishedVersio

    GQ-16, a TZD-derived partial PPARγ agonist, induces the expression of thermogenesis- related genes in brown fat and visceral white fat and decreases visceral adiposity in obese and hyperglycemic mice

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    Background Beige adipocytes comprise a unique thermogenic cell type in the white adipose tissue (WAT) of rodents and humans, and play a critical role in energy homeostasis. In this scenario, recruitment of beige cells has been an important focus of interest for the development of novel therapeutic strategies to treat obesity. PPARγ activation by full agonists (thiazolidinediones, TZDs) drives the appearance of beige cells, a process so-called browning of WAT. However, this does not translate into increased energy expenditure, and TZDs are associated with weight gain. Partial PPARγ agonists, on the other hand, do not induce weight gain, but have not been shown to drive WAT browning. The present study was designed to investigate the effects of GQ-16 on BAT and on browning of WAT in obese mice. Methods Male Swiss mice with obesity and hyperglycemia induced by high fat diet were treated with vehicle, rosiglitazone (4 mg/kg/d) or the TZD-derived partial PPARγ agonist GQ-16 (40 mg/ kg/d) for 14 days. Fasting blood glucose, aspartate aminotransferase, alanine aminotransferase and lipid profile were measured. WAT and brown adipose tissue (BAT) depots were excised for determination of adiposity, relative expression of Ucp-1, Cidea, Prdm16, Cd40 and Tmem26 by RT-qPCR, histological analysis, and UCP-1 protein expression analysis by immunohistochemistry. Liver samples were also removed for histological analysis and determination of hepatic triglyceride content. Results GQ-16 treatment reduced high fat diet-induced weight gain in mice despite increasing energy intake. This was accompanied by reduced epididymal fat mass, reduced liver triglyceride content, morphological signs of increased BAT activity, increased expression of thermogenesis- related genes in interscapular BAT and epididymal WAT, and increased UCP-1 protein expression in interscapular BAT and in epididymal and inguinal WAT. Conclusion This study suggests for the first time that a partial PPARγ agonist may increase BAT activity and induce the expression of thermogenesis-related genes in visceral WAT. General Significance These findings suggest that PPARγ activity might be modulated by partial agonists to induce WAT browning and treat obesity
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