26 research outputs found

    Optical Studies in Red/NIR Persistent Luminescent Cr‐Doped Zinc Gallogermanate (ZGGO:Cr)

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    Zn1+xGa2‐2xGexO4 (ZGGO:Cr)‐persistent phosphor, with a molar fraction, x, of x = 0.1, doped with a 0.5% molar of chromium, was synthesised via solid‐state reaction at 1350 °C for 36 h. X‐ray diffraction measurements and Raman spectroscopy evidence a single crystalline phase corresponding to the cubic spinel structure. Room temperature (RT) photoluminescence (PL) and afterglow decay profiles were investigated using above and below bandgap excitation. In both cases, persistent PL was observed for almost 8 h, mainly originating from a Cr3+ defect, the so‐called N2 optical centre. RT PL excitation and diffuse reflectance allow identification of the best pathways of Cr3+ red/NIR emission, as well as estimation of the ZGGO bandgap energy at 4.82 eV. An in‐depth investigation of the observed luminescence at 15 K and temperature‐dependent PL under site‐selective excitation reveals the spectral complexity of the presence of several optically active Cr3+ centres in the ZGGO host that emit in almost the same spectral region. Furthermore, the temperature dependence of the R‐lines’ intensity indicates the existence of thermal populating processes between the different optical centres. Such observations well account for a wide distribution of defect trap levels available for carrier capture/release, as measured by the persistent luminescence decay, from which the carriers are released preferentially to the N2 Cr3+‐related optical centre.publishersversionpublishe

    Phytoplankton dynamics in relation to seasonal variability and upwelling and relaxation patterns at the mouth of Ria de Aveiro (West Iberian Margin) over a four-year period

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    From June 2004 to December 2007, samples were weekly collected at a fixed station located at the mouth of Ria de Aveiro (West Iberian Margin). We examined the seasonal and inter-annual fluctuations in composition and community structure of the phytoplankton in relation to the main environmental drivers and assessed the influence of the oceano-graphic regime, namely changes in frequency and intensity of upwelling events, over the dynamics of the phytoplankton assemblage. The samples were consistently handled and a final subset of 136 OTUs (taxa with relative abundance > 0.01%) was subsequently submitted to various multivariate analyses. The phytoplankton assemblage showed significant changes at all temporal scales but with an overriding importance of seasonality over longer-(inter-annual) or shorter-term fluctuations (upwelling-related). Sea-surface temperature, salinity and maximum upwelling index were retrieved as the main driver of seasonal change. Seasonal signal was most evident in the fluctuations of chlorophyll a concentration and in the high turnover from the winter to spring phytoplankton assemblage. The seasonal cycle of production and succession was disturbed by upwelling events known to disrupt thermal stratification and induce changes in the phytoplankton assemblage. Our results indicate that both the frequency and intensity of physical forcing were important drivers of such variability, but the outcome in terms of species composition was highly dependent on the available local pool of species and the timing of those events in relation to the seasonal cycle. We conclude that duration, frequency and intensity of upwelling events, which vary seasonally and inter-annually, are paramount for maintaining long-term phytoplankton diversity likely by allowing unstable coexistence and incorporating species turnover at different scales. Our results contribute to the understanding of the complex mechanisms of coastal phytoplankton dynamics in relation to changing physical forcing which is fundamental to improve predictability of future prospects under climate change.Portuguese Foundation for Science and Technology (FCT, Portugal) [SFRH/BPD/ 94562/2013]; FEDER funds; national funds; CESAM [UID/AMB/50017]; FCT/MEC through national funds; FEDERinfo:eu-repo/semantics/publishedVersio

    Neuroprotective effects on microglia and insights into the structure–activity relationship of an antioxidant peptide isolated from Pelophylax perezi

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    © 2022 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly citedTryptophyllins constitute a heterogeneous group of peptides that are one of the first classes of peptides identified from amphibian's skin secretions. Here, we report the structural characterization and antioxidant properties of a novel tryptophyllin-like peptide, named PpT-2, isolated from the Iberian green frog Pelophylax perezi. The skin secretion of P. perezi was obtained by electrical stimulation and fractionated using RP-HPLC. De novo peptide sequencing was conducted using MALDI MS/MS. The primary structure of PpT-2 (FPWLLS-NH2 ) was confirmed by Edman degradation and subsequently investigated using in silico tools. PpT-2 shared physicochemical properties with other well-known antioxidants. To test PpT-2 for antioxidant activity in vitro, the peptide was synthesized by solid phase and assessed in the chemical-based ABTS and DPPH scavenging assays. Then, a flow cytometry experiment was conducted to assess PpT-2 antioxidant activity in oxidatively challenged murine microglial cells. As predicted by the in silico analyses, PpT-2 scavenged free radicals in vitro and suppressed the generation of reactive species in PMA-stimulated BV-2 microglia cells. We further explored possible bioactivities of PpT-2 against prostate cancer cells and bacteria, against which the peptide exerted a moderate antiproliferative effect and negligible antimicrobial activity. The biocompatibility of PpT-2 was evaluated in cytotoxicity assays and in vivo toxicity with Galleria mellonella. No toxicity was detected in cells treated with up to 512 µg/ml and in G. mellonella treated with up to 40 mg/kg PpT-2. This novel peptide, PpT-2, stands as a promising peptide with potential therapeutic and biotechnological applications, mainly for the treatment/prevention of neurodegenerative disorders.This work was financed by FEDER - Fundo Europeu de Desenvolvimento Regional funds through the COMPETE 2020 - Operacional Programme for Competitiveness and Internationalization (POCI), and by Portuguese funds through FCT - Fundação para a Ciência e a Tecnologia in the framework of the project POCI-01-0145-FEDER-031158 – PTDC/BII-BIO/31158/2017. The authors would like to thank the participation and scientific support of the Unit projects UIDB/50006/2020 | UIDP/50006/2020, and the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Universal Faixa ‘B’ (grant number 32103/2018-0). A.P. is a recipient of a post-doctoral grant from the project PTDC/BII-BIO/31158/2017. The authors would like to thank the researcher Roberto Resendes (CiBio, University of the Azores, Ponta Delgada, São Miguel, Azores, Portugal) for the logistical support in the collection of samples. C.P.A acknowledges FCT-MCTES fellowship PD/BD/136860/2018. A.B.-N. and F.C.D.A.L. acknowledge CNPq (grants 420449/2018-3 and 428211/2018-6) for financial support.info:eu-repo/semantics/publishedVersio

    High interannual variability in connectivity and genetic pool of a temperate clingfish matches oceanographic transport predictions

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    Adults of most marine benthic and demersal fish are site-attached, with the dispersal of their larval stages ensuring connectivity among populations. In this study we aimed to infer spatial and temporal variation in population connectivity and dispersal of a marine fish species, using genetic tools and comparing these with oceanographic transport. We focused on an intertidal rocky reef fish species, the shore clingfish Lepadogaster lepadogaster, along the southwest Iberian Peninsula, in 2011 and 2012. We predicted high levels of self-recruitment and distinct populations, due to short pelagic larval duration and because all its developmental stages have previously been found near adult habitats. Genetic analyses based on microsatellites countered our prediction and a biophysical dispersal model showed that oceanographic transport was a good explanation for the patterns observed. Adult sub-populations separated by up to 300 km of coastline displayed no genetic differentiation, revealing a single connected population with larvae potentially dispersing long distances over hundreds of km. Despite this, parentage analysis performed on recruits from one focal site within the Marine Park of Arrabida (Portugal), revealed self-recruitment levels of 2.5% and 7.7% in 2011 and 2012, respectively, suggesting that both long-and short-distance dispersal play an important role in the replenishment of these populations. Population differentiation and patterns of dispersal, which were highly variable between years, could be linked to the variability inherent in local oceanographic processes. Overall, our measures of connectivity based on genetic and oceanographic data highlight the relevance of long-distance dispersal in determining the degree of connectivity, even in species with short pelagic larval durations

    The national inventory of geological heritage: methodological approach and results

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    A existência de um inventário nacional de património geológico é fundamental para se poderem implementar estratégias de geoconservação. Este trabalho apresenta a metodologia usada no desenvolvimento do mais completo inventário de geossítios, realizado até ao momento em Portugal, assim como os principais resultados obtidos. O inventário vai integrar o Sistema de Informação do Património Natural e o Cadastro Nacional dos Valores Naturais Classificados, ambos geridos pelo Instituto de Conservação da Natureza e da Biodiversidade.The existence of a national inventory of the geological heritage is of paramount importance for the implementation of a geoconservation strategy. This paper presents the methodological approach used to produce the most complete geosites inventory in Portugal, so far, and the obtained results. This inventory will be uploaded into the National Database of Natural Heritage managed by the Portuguese authority for nature conservation.Este trabalho é apoiado pela Fundação para a Ciência e a Tecnologia, através do financiamento plurianual do CGUP e do projecto de investigação “Identificação, caracterização e conservação do património geológico: uma estratégia de geoconservação para Portugal” (PTDC/CTE-GEX/64966/2006).info:eu-repo/semantics/publishedVersio

    Manifestações fonoaudiológicas relatadas por pais de crianças com hipotireoidismo congênito Speech-language pathology manifestations reported by parents of children with congenital hypothyroidism

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    OBJETIVO: Identificar manifestações fonoaudiológicas apresentadas por crianças com hipotireoidismo congênito e investigar a associação de tais manifestações com a época do diagnóstico e o início do tratamento. MÉTODOS: Responsáveis por 15 crianças diagnosticadas com hipotireoidismo congênito e atendidas pelo Serviço de Referência em Triagem Neonatal dos estados de Rondônia e Acre responderam a um questionário no qual deveriam relatar principalmente queixas fonoaudiológicas. A idade das crianças variou de 2 a 7 anos, 67% de meninos e 33% de meninas. A média de idade da época do diagnóstico foi de 1 mês e 3 dias e o tratamento iniciou-se, em média, com 1 mês e 6 dias. A dosagem do medicamento variou entre 5 mg/dia e 100 mg/dia. RESULTADOS: As queixas relatadas foram: atraso para início da linguagem oral, trocas na fala, fala ininteligível, comportamento agitado e comportamento nervoso. Alguns responsáveis não referiram queixas. Verificou-se que a maioria dos sujeitos apresentou problemas na fala (80%) e a menor parte (7,7%), alteração auditiva. Para aqueles que referiram queixa, a média da época do diagnóstico e do início do tratamento foi mais tardia quando comparado àqueles que não as relataram. CONCLUSÃO: Foram relatadas manifestações fonoaudiológicas, principalmente relacionadas à fala. Além disso, houve associação entre a presença de queixa e problema de fala com a época do diagnóstico e o início do tratamento. Sugere-se a inserção do fonoaudiólogo no acompanhamento das crianças com hipotireoidismo congênito.<br>PURPOSE: To identify speech-language pathology manifestations presented by children with congenital hypothyroidism, and to investigate the association of such manifestations with the time of diagnosis and beginning of treatment. METHODS: Caregivers of 15 children diagnosed with congenital hypothyroidism who attended the Reference Service on Neonatal Screening of the states of Rondônia and Acre answered a questionnaire in which they should report mainly speech-language pathology complaints. Children's age ranged from 2 to 7 years, 67% of boys and 33% of girls. The average age at the time of diagnosis was 1 month and 3 days, and treatment started, in average, at 1 month and 6 days. The dosage of the drug varied from 5 mg/day to 100 mg/day. RESULTS: The complaints reported were: delay in the onset of oral language, speech alterations, unintelligible speech, agitated and nervous behavior. Some caregivers did not report any complaints. It was found that most subjects had problems with speech (80%), and a few had hearing impairment (7.7%). For those who reported complaints, mean time of diagnosis and beginning of treatment was delayed when compared to those who did not report. CONCLUSION: Speech-language pathology manifestations were reported, especially regarding speech. Moreover, there was association between the presence of complaints and speech disorders with the time of diagnosis and beginning of treatment. It is suggested the inclusion of the speech-language pathologist and audiologist in the team monitoring the development of children with congenital hypothyroidism
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