912 research outputs found

    Runoff at the micro-plot and slope scale following wildfire, central Portugal

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    Through their effects on soil properties and vegetation/litter cover, wildfires can strongly enhance overland flow generation and accelerate soil erosion [1] and, thereby, negatively affect land-use sustainability as well as downstream aquatic and flood zones. Wildfires are a common phenomenon in present-day Portugal, devastating in an average year some 100.000 ha of forest and woodlands and in an exceptional year like 2003 over 400.000 ha. There therefore exists a clear need in Portugal for a tool that can provide guidance to post-fire land management by predicting soil erosion risk, on the one hand, and, on the other, the mitigation effectiveness of soil conservation measures. Such a tool has recently been developed for the Western U.S.A. [3: ERMiT] but its suitability for Portuguese forests will need to be corroborated by field observations. Testing the suitability of existing erosion models in recently burned forest areas in Portugal is, in a nutshell, the aim of the EROSFIRE projects. In the first EROSFIRE project the emphasis was on the prediction of erosion at the scale of individual hill slopes. In the ongoing EROSFIRE-II project the spatial scope is extended to include the catchment scale, so that also the connectivity between hill slopes as well as channel and road processes are being addressed. Besides ERMiT, the principal models under evaluation for slope-scale erosion prediction are: (i) the variant of USLE [4] applied by the Portuguese Water Institute after the wildfires of 2003; (ii) the Morgan–Morgan–Finney model (MMF) [5]; (iii) MEFIDIS [6]. From these models, MEFIDIS and perhaps MMF will, after successful calibration at the slope scale, also be applied for predicting catchment-scale sediment yields of extreme events

    Runoff and erosion at the micro-plot and slope scale in a small burnt catchment, central Portugal

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    Wildfires can have important impacts on hydrological processes and soil erosion in forest catchments, due to the destruction of vegetation cover and changes to soil properties. However, the processes involved are non-linear and not fully understood. This has severely limited the understanding on the impacts of wildfires, especially in the up-scaling from hillslopes to catchments; in consequence, current models are poorly adapted for burnt forest conditions. The objective of this presentation is to give an overview of the hydrological response and sediment yield from the micro-plot to slope scale, in the first year following a wildfire (2008/2009) that burnt an entire catchment nearby the Colmeal village, central Portugal. The overview will focus on three slopes inside the catchment, with samples including: • Runoff at micro-plot scale (12 bounded plots) and slope scale (12 open plots); • Sediments and Organic Matter loss at micro-plot scale (12 bounded plots) and slope scale (12 open plots plus 3 Sediment fences); • Rainfall and Soil moisture data; • Soil Water Repellency and Ground Cover data. The analysis of the first year following the wildfire clearly shows the complexity of runoff generation and the associated sediment transport in recently burnt areas, with pronounced differences between hillslopes and across spatial scales as well as with marked variations through time. This work was performed in the framework of the EROSFIRE-II project (PTDC/AGR-CFL/70968/2006) which has as overall aim to predict soil erosion risk in recently burnt forest areas, including common post-fire forest management practices; the project focuses on the simultaneous measurement of runoff and soil erosion at multiple spatial scales.The results to be presented in this session are expected to show how sediment is generated, transported and exported in the Colmeal watershed; and contribute to understand and simulate erosion processes in burnt catchments, including for model development and evaluation

    Comprehensive analysis and comparison of digital current control techniques for active rectifiers

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    This paper presents a comprehensive analysis and comparison of digital current control techniques for active rectifiers. These rectifiers are connect-ed to the power grid and are controlled aiming to obtain sinusoidal grid currents and unitary power factor. In this context this paper presents the principle of operation of a full-bridge full-controlled active rectifier, which is controlled by different digital current control techniques, namely, proportional-integral (PI) in stationary frame, PI in synchronous frame, PI sinewave (PIS), feedforward, sliding mode, and predictive. These digital current control techniques are explained in detail and is established a comparison in terms of their current errors in steady-state, as well as in terms of their digital implementation using the digital signal processor (DSP) TMS320F28335 from Texas Instruments.FCTCOMPETE: POCI-01-0145-FEDER-00704

    A single-phase current-source converter combined with a hybrid converter for interfacing an electric vehicle and a renewable energy source

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    This paper presents a single-phase current-source converter (CSC) combined with a hybrid converter on the dc-link, allowing to interface an electric vehicle (EV) and a renewable energy source (RES). Therefore, the interface with the power grid is only performed through the CSC, which also permits the operation as shunt active power filter (SAPF), allowing to compensate power quality problems related with current and low power factor in the electrical installation. The whole system is composed by two main power stages, namely, the CSC that is responsible for compensating the current harmonics and low power factor, as well as operating as a grid-tied inverter or as an active rectifier, and the hybrid converter that is responsible for interfacing the dc-link of the CSC with the converters for the EV and the RES interfaces. As demonstrated along the paper, the CSC, combined with the hybrid converter on the dc-link, allows the operation as SAPF, as well as the operation in bidirectional mode, specifically for the EV operation, and also for injecting power from the RES. In the paper, the power electronics structure is described and the principle of operation is introduced, supported by the description of the control algorithms. The validation results show the proper operation of the CSC, combined with the hybrid converter on the dc-link, for the main conditions of operation, namely exchanging power with the power grid in bidirectional mode and operating as a SAPF.This work has been supported by FCT – Fundação para a Ciência e Tecnologia with-in the Project Scope: UIDB/00319/2020. This work has been supported by the FCT Project newERA4GRIDs PTDC/EEI-EEE/30283/2017 and the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017

    A comprehensive comparison of voltage and current control techniques for three-phase VSI converters

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    Converting electrical energy from direct current to alternate current, or vice versa, is one of the most frequently performed tasks in today’s electrical systems. The Voltage Source Inverter (VSI) is the most widely used topology to accomplish this task. This paper compares the performance of three control algorithms for voltage source inverter (VSI) with PI, PR and MP control algorithms were applied for voltage control and current control. For voltage control the VSI synthesizes the sinusoidal voltage system for an islanded application. In current control the VSI injects energy into the power grid by synthesizing sinusoidal currents. A general comparison is made of the performance of the three control algorithms under the presented conditions, helping to choose the control algorithm to use in a given application.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UIDB/00319/2020. This work has been supported by the FCT Project QUALITY4POWER PTDC/EEI-EEE/28813/2017, and by the FCT Project DAIPESEV PTDC/EEI-EEE/30382/2017. Mr. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018 granted by the Portuguese FCT foundation

    A unified power converter for solar PV and energy storage in dc microgrids

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    This paper deals with the development and experimental validation of a unified power converter for application in dc microgrids, contemplating the inclusion of solar photovoltaic (PV) panels and energy storage systems (ESS), namely batteries. Considering the limitations presented by the current structure of the power grid, mostly highlighted by the accentuated integration of emerging technologies (ESS, renewables, electric vehicles, and electrical appliances that natively operate in dc), it is extremely pertinent to adopt new topologies, architectures, and paradigms. In particular, decentralized power systems, unified topologies, and correspondent control algorithms are representative of a new trend towards a reduction in the number of power converters. Thus, the developed solution is designed to operaSAVE-15te at a nominal power of 3.6 kW, with a switching frequency of 100 kHz, and in four operation modes concerning power flow: (i) solar PV panels to batteries (PV2B); (ii) solar PV panels to dc grid (PV2G); (iii) batteries to dc grid (B2G); (iv) dc grid to batteries (G2B). Moreover, a dual active bridge converter guarantees galvanic isolation, while two back-end dc–dc converters are responsible for interfacing solar PV panels and batteries. The experimental validation of the proposed unified power converter proves its application value to self-consumption production units.This work has been supported by FCT—Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. This work has been supported by the MEGASOLAR Project POCI-01-0247-FEDER-047220

    Targeting cancer resistance via multifunctional gold nanoparticles

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    POCI-01-0145-FEDER-007728 SFRH/BD/120030/2016 PD/BD/105734/2014 Pest-OE/UID/DTP/04138/2013Resistance to chemotherapy is a major problem facing current cancer therapy, which is continuously aiming at the development of new compounds that are capable of tackling tumors that developed resistance toward common chemotherapeutic agents, such as doxorubicin (DOX). Alongside the development of new generations of compounds, nanotechnology-based delivery strategies can significantly improve the in vivo drug stability and target specificity for overcoming drug resistance. In this study, multifunctional gold nanoparticles (AuNP) have been used as a nanoplatform for the targeted delivery of an original anticancer agent, a Zn(II) coordination compound [Zn(DION)2]Cl2 (ZnD), toward better efficacy against DOX-resistant colorectal carcinoma cells (HCT116 DR). Selective delivery of the ZnD nanosystem to cancer cells was achieved by active targeting via cetuximab, NanoZnD, which significantly inhibited cell proliferation and triggered the death of resistant tumor cells, thus improving efficacy. In vivo studies in a colorectal DOX-resistant model corroborated the capability of NanoZnD for the selective targeting of cancer cells, leading to a reduction of tumor growth without systemic toxicity. This approach highlights the potential of gold nanoformulations for the targeting of drug-resistant cancer cells.publishersversionpublishe

    A new model of laryngitis: neuropeptide, cyclooxygenase, and cytokine profile

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    Objectives/Hypothesis: To develop and characterize a new model of laryngeal inflammation by analyzing the presence of neurogenic peptides and expression of cyclooxygenases (COX) and cytokines in the mucosa.Study Design: Laryngitis induced by nasogastric intubation (NGI) was evaluated by histopathologic changes of the mucosa, alterations in calcitonin gene related peptide (CGRP) and substance P (SP) neuropeptides in sensory fibers, and COX-1,2, and cytokine (interleukin [IL]-1, IL-6, IL-10, tumor necrosis factor [TNF]-alpha) expression in the laryngeal mucosa.Methods: Rats submitted to NGI for 1 to 5 weeks were compared with controls. Laryngeal sections were immunostained for stereologic analysis of SP and CGRP fiber density and number of mucosal cells expressing COX-2. Alterations in inflammatory mediators were evaluated by quantitative reverse-transcriptase polymerase chain reaction.Results: NGI induced metaplasia of the epithelium and narrowing of the laryngeal lumen because of hypertrophy of laryngeal glandules and edema. An initial decrease in CGRP- and SP-immunoreactive fibers in the laryngeal mucosa (1-3 wk) was reverted with time (5 wk). COX-2 expression in mucosal cells increased progressively, reaching a maximum level at 5 weeks, and was observed in mononuclear immune cells, which is indicative of a chronic inflammatory process. In regard to mRNA expression levels of inflammatory mediators, TNF-alpha was increased during the 5 week NGI, and IL-10 decreased during the 5 weeks,whereas IL-beta, IL-6, and COX-2 increased in the first 1 to 2 weeks and returned to baseline at 5 weeks.Conclusions: This NGI model results in laryngeal chronic inflammation without direct mechanical aggression of the mucosa and may contribute to the study of future therapeutic approaches to this pathology.FEDERFundação para a Ciência e Tecnologia (FCT) - POCTI/NSE/46399/2002Fundação Calouste Gulbenkian - projecto nº 7455

    Novel putative candidate genes associated with umbilical hernia in pigs.

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    Abstract: Umbilical hernia is one of the most frequent anatomical defects in pigs in which abdominal contents protrude through the umbilical ring. This condition is considered to have a multifactorial basis in which environmental, infectious and genetic factors play a role. However, a better understanding about the genetic components involved in the umbilical hernia development has not yet been achieved. Although a few studies have mapped QTL for umbilical hernia, just a few candidate genes were reported. Therefore, the aim of this study was to identify genomic regions related to the development of umbilical hernias in pigs and search for potential candidate genes. A GWAS was performed with 92 cases and 233 control crossbred pigs. Five SNPs were associated with umbilical hernia: on SSC4/SSC6/SSC13 and one with unknown position. Candidate genes TBX15 and WARS2 were identified close to the SNP on SSC4. Another two candidate genes were located near the SNP associated with umbilical hernia on SSC13 (LIPI and RBM11). Further validation of these genes should be performed to improve the knowledge about umbilical hernia development in order to improve pig welfare and production by eliminating susceptible animals through genetic selection Resumo: A hérnia umbilical é um dos defeitos anatômicos mais freqüentes em suínos nos quais o conteúdo abdominal se projeta através do anel umbilical. Considera-se que esta condição tem uma base multifatorial na qual fatores ambientais, infecciosos e genéticos desempenham um papel. Entretanto, um melhor entendimento sobre os componentes genéticos envolvidos no desenvolvimento da hérnia umbilical ainda não foi alcançado. Embora alguns estudos tenham mapeado o QTL para a hérnia umbilical, apenas alguns genes candidatos foram relatados. Portanto, o objetivo deste estudo foi identificar regiões genômicas relacionadas ao desenvolvimento de hérnias umbilicais em porcos e buscar potenciais genes candidatos. Um GWAS foi realizado com 92 casos e 233 porcos cruzados de controle. Cinco SNPs foram associados com hérnia umbilical: em SSC4 / SSC6 / SSC13 e um com posição desconhecida. Os genes candidatos TBX15 e WARS2 foram identificados próximos ao SNP em SSC4. Outros dois genes candidatos foram localizados perto do SNP associado à hérnia umbilical na SSC13 (LIPI e RBM11). A validação adicional desses genes deve ser realizada para melhorar o conhecimento sobre o desenvolvimento de hérnia umbilical, a fim de melhorar o bem-estar ea produção de suínos, eliminando os animais suscetíveis por meio da seleção genétic

    Erratum for Oliveira et al., "K2 Capsule Depolymerase Is Highly Stable, Is Refractory to Resistance, and Protects Larvae and Mice from Acinetobacter baumannii Sepsis"

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    Volume 85, no. 17, e00934-19, 2019, https://doi.org/10.1128/AEM.00934-19. Page 10, Acknowledgments, lines 4 and 5: POCI-01-0145-FEDER-016678 should read POCI-01-0145-FEDER-016643.info:eu-repo/semantics/publishedVersio
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