Caldeiras Vulcânicas dos Açores : processos de formação e erupções associadas

A secção UAciência é coordenada pelo Professor Universitário Armindo Rodrigues.[…]. O estudo dos processos de formação das caldeiras dos Açores tem sido uma das linhas de investigação desenvolvidas pelo Centro de Vulcanologia e Avaliação de Riscos Geológicos (CVARG). Na sequência de trabalhos realizados, tem-se verificado que as caldeiras açorianas não se formaram de uma só vez, mas resultam da coalescência de vários colapsos parciais dos edifícios em consequência de diferentes erupções explosivas de magnitude moderada. As caldeiras formadas por este processo são conhecidas como caldeiras de incremento (incremental calderas em inglês). […].info:eu-repo/semantics/publishedVersio

Deficiency of essential elements in volcanic soils : potential harmful health effects on grazing cattle

Several essential nutrients such as Fe, Co, Cu, I, Se, and Zn are vital to grazing cattle as they play a significant role in intracellular enzyme systems, with antioxidant and repair functions of DNA lesions. Feeds may supply most essential nutrients in adequate amounts. However, essential nutrient deficiencies are common and are mainly related to the geochemical characteristics of the soils, inherited from parent rocks. This study aims to assess the concentrations of the selected essential nutrients in topsoils and pasture grass from São Miguel Island (Azores) and discuss the possible effects of its deficiency in grazing cattle health. Sixty-eight samples of agricultural (pastures) topsoil and thirty samples of pasture grass were collected throughout São Miguel Island in areas with basaltic and trachytic parent rocks. Soil physicochemical properties and geochemical baselines of selected elements were determined on composite samples of soil and pasture grass in each site. Results indicate that the highest concentrations of the selected essential nutrients were observed in areas with basaltic soils, while the lowest values were found in areas with trachytic soils. These differences are considered of geogenic origin since they result from the weathering of volcanic parent rocks with different geochemical compositions. Data indicate a lack of some essential nutrients in topsoils (Co and Se) and/or pasture grass (Co, Cu, Se, and Zn) that can contribute to harmful health effects on grazing cattle. The uneven distribution of essential nutrients in topsoil and pasture grass and their deficiency can lead to several health problems in the cattle since these elements regulate physiological functions in biological systems. The identification of these deficit sites is important as it can help farmers to implement soil and/or animal supplementation programs to diminish possible health problems.Diana Linhares was supported by a postdoc fellowship from the Fundo Regional da Ciencia (Regional Government of the Azores) (M3.1.a/F/004/2018).info:eu-repo/semantics/publishedVersio

Eruption Style, Emplacement Dynamics and Geometry of Peralkaline Ignimbrites: Insights From the Lajes-Angra Ignimbrite Formation, Terceira Island, Azores

Ignimbrites are relatively uncommon on ocean island volcanoes and yet they constitute a significant portion of the stratigraphy of Terceira Island (Azores). The Lajes-Angra Ignimbrite Formation (ca. 25 cal ka BP) contains the youngest ignimbrites on Terceira and records two ignimbrite-forming eruptions of Pico Alto volcano that occurred closely spaced in time. Here, we present the first detailed lithofacies analysis and architecture of the Angra and Lajes ignimbrites, complemented by petrographic, mineral chemical, whole rock and groundmass glass geochemical data. The two ignimbrites have the same comenditic trachyte composition, but show considerable variability in trace element and groundmass glass compositions, revealing complex petrogenetic processes in the Pico Alto magma reservoir prior to eruption. The Angra Ignimbrite has a high-aspect ratio and is massive throughout its thickness. It was formed by a small-volume but sustained pyroclastic density current (PDC) fed by a short-lived, low pyroclastic fountain. Overall, the PDC had high particle concentration, granular fluid-based flow conditions and was mostly channelled into a valley on the south part of Terceira. By contrast, the Lajes Ignimbrite has a low-aspect ratio and shows vertical and lateral lithofacies variations. It was formed by a sustained quasi-steady PDC generated from vigorous and prolonged pyroclastic fountaining. The ignimbrite architecture reveals that depositional conditions of the parent PDC evolved as the eruption waxed. The dilute front of the current rapidly changed to a high particle concentration, granular fluid-based PDC that extended to the north and south coasts, with limited capacity to surmount topographic highs. Contrary to what is commonly assumed, the low-aspect ratio of the Lajes Ignimbrite is interpreted to result from deposition of a relatively low velocity PDC over a generally flat topography. This work highlights that the geometry (aspect ratio) of ignimbrites does not necessarily reflect the kinetic energy of PDCs and thus should not be used as a proxy for PDC emplacement dynamics. Although the probability of an ignimbrite-forming eruption on Terceira is relatively low, such a scenario should not be underestimated, as a future event would have devastating consequences for the island’s 55,000 inhabitants

Preditores de mortalidade total e eventos arrítmicos graves em pacientes com insuficiência cardíaca não isquêmica : o papel da galectina-3

Background: Risk stratification remains clinically challenging in patients with heart failure (HF) of non-ischemic etiology. Galectin-3 is a serum marker of fibrosis that might help in prognostication. Objective: To determine the role of galectin-3 as a predictor of major arrhythmic events and overall mortality. Methods: We conducted a prospective cohort study that enrolled 148 non-ischemic HF patients. All patients underwent a comprehensive baseline clinical and laboratory assessment, including levels of serum galectin-3. The primary outcome was the occurrence of arrhythmic syncope, appropriate implantable cardioverter defibrillator therapy, sustained ventricular tachycardia, or sudden cardiac death. The secondary outcome was all-cause death. For all statistical tests, a two-tailed p-value22.5 ng/mL (highest quartile) did not predict serious arrhythmic events (HR: 1.98, p=0.152). Independent predictors of the primary outcome were left ventricular end-diastolic diameter (LVEDD)>73mm (HR: 3.70, p=0.001), exercise periodic breathing (EPB) on cardiopulmonary exercise testing (HR: 2.67, p=0.01), and non-sustained ventricular tachycardia (NSVT)>8 beats on Holter monitoring (HR: 3.47, p=0.027). Predictors of all-cause death were galectin-3>22.5 ng/mL (HR: 3.69, p=0.001), LVEDD>73mm (HR: 3.35, p=0.003), EPB (HR: 3.06, p=0.006), and NSVT>8 beats (HR: 3.95, p=0.007). The absence of all risk predictors was associated with a 91.1% negative predictive value for the primary outcome and 96.6% for total mortality. Conclusions: In non-ischemic HF patients, elevated galectin-3 levels did not predict major arrhythmic events but were associated with total mortality. Absence of risk predictors revealed a prevalent subgroup of HF patients with an excellent prognosis.Fundamento: A estratificação de risco continua sendo clinicamente desafiadora em pacientes com insuficiência cardíaca (IC) de etiologia não isquêmica. A galectina-3 é um marcador sérico de fibrose que pode ajudar no prognóstico. Objetivo: Determinar o papel da galectina-3 como preditora de eventos arrítmicos graves e mortalidade total. Métodos: Este é um estudo de coorte prospectivo que incluiu 148 pacientes com IC não isquêmica. Todos os pacientes foram submetidos a uma avaliação clínica e laboratorial abrangente para coleta de dados de referência, incluindo níveis de galectina-3 sérica. O desfecho primário foi a ocorrência de síncope arrítmica, intervenções apropriadas do cardioversor desfibrilador implantável, taquicardia ventricular sustentada ou morte súbita cardíaca. O desfecho secundário foi a morte por todas as causas. Para todos os testes estatísticos, considerou-se significativo o valor p22,5 ng/mL (quartil mais alto) não foi preditora de eventos arrítmicos graves (HR: 1,98; p=0,152). Os preditores independentes do desfecho primário foram diâmetro diastólico final do ventrículo esquerdo (DDFVE)>73 mm (HR: 3,70; p=0,001), ventilação periódica durante o exercício (VPE) no teste de esforço cardiopulmonar (HR: 2,67; p=0,01) e taquicardia ventricular não sustentada (TVNS)>8 batimentos na monitorização por Holter (HR: 3,47; p=0,027). Os preditores de morte por todas as causas foram: galectina-3>22,5 ng/mL (HR: 3,69; p=0,001), DDFVE>73 mm (HR: 3,35; p=0,003), VPE (HR: 3,06; p=0,006) e TVNS>8 batimentos (HR: 3,95; p=0,007). A ausência de todos os preditores de risco foi associada a um valor preditivo negativo de 91,1% para o desfecho primário e 96,6% para a mortalidade total. Conclusões: Em pacientes com IC não isquêmica, níveis elevados de galectina-3 não foram preditores de eventos arrítmicos graves, mas foram associados à mortalidade total. A ausência de preditores de risco revelou um subgrupo prevalente de pacientes com IC com excelente prognóstico

The mycobacteriophage ms6 lysb n-terminus displays peptidoglycan binding affinity

Funding Information: Funding: This work was supported in part by Fundação para a Ciência e Tecnologia (FCT-MCES, Portugal) Grant PTDC/IMI-MIC/0694/2012 to MP and PTDC/BIA-MIC/30746/2017 to SF. AG (SFRH/BD/87685/2012) was a recipient PhD fellowship from FCT-MCES, Portugal. Funding Information: This work was supported in part by Funda??o para a Ci?ncia e Tecnologia (FCT-MCES, Portugal) Grant PTDC/IMI-MIC/0694/2012 to MP and PTDC/BIA-MIC/30746/2017 to SF. AG (SFRH/BD/87685/2012) was a recipient PhD fellowship from FCT-MCES, Portugal. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Double-stranded DNA bacteriophages end their lytic cycle by disrupting the host cell envelope, which allows the release of the virion progeny. Each phage must synthesize lysis proteins that target each cell barrier to phage release. In addition to holins, which permeabilize the cytoplasmic membrane, and endolysins, which disrupt the peptidoglycan (PG), mycobacteriophages synthesize a specific lysis protein, LysB, capable of detaching the outer membrane from the complex cell wall of mycobacteria. The family of LysB proteins is highly diverse, with many members presenting an extended N-terminus. The N-terminal region of mycobacteriophage Ms6 LysB shows structural similarity to the PG-binding domain (PGBD) of the φKZ endolysin. A fusion of this region with enhanced green fluorescent protein (Ms6LysBPGBD-EGFP) was shown to bind to Mycobacterium smegmatis, Mycobacterium vaccae, Mycobacterium bovis BGC and Mycobacterium tuberculosis H37Ra cells pretreated with SDS or Ms6 LysB. In pulldown assays, we demonstrate that Ms6 LysB and Ms6LysBPGBD-EGFP bind to purified peptidoglycan of M. smegmatis, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis, demonstrating affinity to PG of the A1γ chemotype. An infection assay with an Ms6 mutant producing a truncated version of LysB lacking the first 90 amino acids resulted in an abrupt lysis. These results clearly demonstrate that the N-terminus of Ms6 LysB binds to the PG.publishersversionpublishe

The recent volcanism of Flores Island (Azores): Stratigraphy and eruptive history of Funda Volcanic System

Monogenetic volcanoes occur in many different geotectonic settings and are usually small and short-lived. They can experience a variety of eruptive styles, even during the same eruption. In monogenetic volcanic fields, volcanism usually migrates to different locations over time, making volcanic hazard assessment very challenging. The eruptive history of a volcanic region, including the size, style, and location of previous eruptions, provides valuable information to help predict the behaviour of future volcanic events and their associated hazards. Here, we reconstruct for the first time the eruptive history of the Funda Volcanic System (FVS), one of the most recent (~3 ka) monogenetic eruptive centres of Flores Island (Azores), based on a detailed tephrostratigraphic work coupled with geochemical analysis of glass shards and radiocarbon dating. We identified at least three volcanic events at FVS spaced by time intervals of ~100 yr. The first event (3430 cal yr BP) was a small Strombolian eruption, the second event (3330 cal yr BP) started as a violent Strombolian eruption and may have ended as phreatomagmatic, and the third event (3250 cal yr BP) was exclusively phreatomagmatic. Our results demonstrate that volcanism at the FVS was more prolonged and recurrent than previously reported. Moreover, we show that the FVS experienced different eruptive styles in a short timeframe, ranging from small basaltic eruptions to violent explosive phreatomagmatic events. Such diversity of eruptive styles results in different volcanic products, which have different hazard implications. Our new results contribute to the knowledge of the recent volcanic activity of Flores Island, and we anticipate them to be of paramount importance for future volcanic hazard assessment studies