Bioclimatic modelling in the holocene and in future warming scenarios in Arbutus unedo L.

Growing forests wildfires in Portugal are an increasing concern since forests in the Mediterranean region are vulnerable to recent global warming. Long-term negative effects are expected on the vegetation with the coming increasing drought. The strawberry tree (Arbutus unedo L.) displays potential to be a successfully business-like cultured in several regions of Portugal and southern Europe, as it is well adapted to climate and soils. In Portugal, this species has been used by local populations particularly for spirit production and for fruit consumption, although it has different possible commercial uses, from processed and fresh fruit production to ornamental, pharmaceutical and chemical applications. In addition, due to its pioneer status, it is valuable for land recovery and desertification avoidance, besides being fire resistant. The available strawberry tree’s data is presence-only. For modelling purposes, a set of placements within the landscape of interest (Portugal) was applied. The species, observed in 318 plots, together with a vector of environmental covariates (7 bioclimatic attributes, slope and altitude) and a defined background were used for modeling purposes. Maxent 3.4.1 was the used software, where the estimated quantity is the probability of the presence of the species, conditioned on the environment. Maxent uses the environmental covariate data from the occurrence records and the background sample, to estimate the ratio between the conditional density of the covariates at the presence sites and the marginal (i.e., unconditional) density of covariates across the study area and so, estimating the relative suitability of one place vs. another. Three different climate scenarios (control run; 2050 and 2070) were tested for two emission scenarios (RCP 4.5 and RCP 8.5, WorldClim), besides the past, 6,000 BP (Mid-Holocene). The reduction of habitat suitable for this species is very significant in the southern regions, even for the best warming scenario (RCP 4.5) in 2050. Central and Northern mountain regions are predicted refuge for this species. Forest policies and management should consider the impact of climate change on the usable areas for forestry, seeing a case-study species particularly adapted to the Mediterranean regions and wildfires, such as strawberry tree. The distribution of the species in the Middle Holocene agrees with previous genetic and fossils studies in the region, which supported two putative refuges for the species since the Last Glacial Maximum and a cryptic refugia in the East-Central mountain region.info:eu-repo/semantics/publishedVersio

A motivação dos alunos em simulação empresarial: análise de um ano lectivo

Com o objectivo de avaliar a motivação dos alunos e de identificar os aspectos que tendem a explicar a motivação, elaborou-se um inquérito por questionário aos alunos de Projecto- Simulação Empresarial- do curso de Contabilidade no ano lectivo de 2011/2012 da Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Bragança. Os resultados obtidos revelam uma elevada motivação por parte dos alunos ao longo da Unidade Curricular, tendo sido possível identificar um conjunto de aspectos influenciadores de uma motivação mais elevada, nomeadamente a “Importância na formação global de um licenciado em Contabilidade”, a “Consolidação de conhecimentos” e porque “Proporciona o desenvolvimento da capacidade de iniciativa”

Deleção cromossómica intersticial em 14q “de novo”: apresentação de um caso

Introdução: As deleções intersticiais são anomalias cromossómicas estruturais, desequilibradas, resultantes de dois pontos de quebra, frequentemente associadas a quadros clínicos anormais devido à perda de material genético ativo (eucromatina). As consequências fenotípicas dependem do segmento cromossómico perdido e do número de genes aí localizados. Material e Métodos: Os autores apresentam o caso de um indivíduo do sexo masculino, de 11 anos de idade, referenciado para estudo citogenético por apresentar um quadro clínico de atraso de desenvolvimento psicomotor, défice cognitivo e problemas de comportamento. Realizaram-se culturas sincronizadas de linfócitos de sangue periférico, bandas GTG de alta resolução e, posteriormente, estudos de hibridação in situ por fluorescência (FISH) com sondas de pintura cromossómica total e subtelomérica, específicas para o cromossoma 14. Resultados: A análise das metafases revelou a presença de uma anomalia estrutural no cromossoma 14, interpretada como uma deleção intersticial do segmento compreendido entre as bandas 14q24.3 e 14q32.1. A análise por FISH permitiu confirmar esta deleção intersticial. Como os cariótipos dos pais foram normais, conclui-se que esta anomalia cromossómica é “de novo”, estabelecendo-se o cariótipo do doente como: 46,XY,del(14)(q24.3q32.1).ish del(14)(wcp 14+,SHGC36156+)dn Discussão: A deleção intersticial encontrada no cromossoma 14 implica uma monossomia do segmento 14q24.3→14q32.1. As alterações descritas mais comuns, associadas a esta deleção, incluem ADPM e algumas malformações minor. Os autores apresentam este caso pela raridade da anomalia citogenética encontrada e comparam-no com a literatura atual

Ácido ascórbico, betalaínas, e fenóis totais em ecótipos de Opuntia spp.

O género Opuntia spp. pertence à família Cactaceae, sendo a espécie Opuntia ficus-indica (OFI) a que tem maior importância económica. Em frutos de vinte populações provenientes de quatro espécies do género Opuntia spp. (OFI, O. robusta, O. dillenii and O. elata), com origem em Portugal, foram estudadas as características cromáticas, a acidez, o pH, o teor em sólidos solúveis totais (SST) e ainda os teores em ácido ascórbico (AA), betalaínas e fenóis totais (FT). As cultivares Italianas de OFI ‘Bianca’, ‘Gialla’ e ‘Rossa’ foram incluídas como termo de comparação. Os valores mais elevados de acidez foram registados nos frutos de O. dillenii e O. elata e os menores em OFI. Os frutos de O. dillenii apresentaram os teores mais elevados de betalaínas e FT, ao passo que as concentrações mais elevadas de AA foram registadas nos frutos de O. elata. Os ecótipos de OFI mostraram variação na concentração de compostos bioativos. Em OFI, a cv. de polpa vermelha ‘Rossa’ é a que apresenta maior concentração de betalaínas, seguida pelos ecótipos de polpa laranja e, finalmente, os ecótipos de polpa branca. Os valores mais elevados de FT foram encontrados nos ecótipos de polpa branca. O género Opuntia spp. é uma fonte de compostos bioativos, pelo que o consumo dos seus frutos representa uma boa forma de ingestão de compostos de elevado valor nutricional

A kinetic approach to homogeneous Ziegler type polymerization. Transient state

In this paper we present a kinetic approach to the analysis of transient-state homogeneous Ziegler-Natta polymerization activity data. The main features of the experimental data are discussed and fitted to transient kinetic models.info:eu-repo/semantics/publishedVersio

Homogeneous Ziegler-Natta polymerisation: A kinetic approach .2. Transient-state kinetics

An integrated view is presented of several possible mechanisms applicable to the interpretation of homogeneous Ziegler-Natta polymerisation. In this paper, the transient aspects related to the kinetics of Ziegler-Natta polymerisation are investigated. Extensive data are used to construct kinetic profiles (rM vs. t) from a theoretical approach. Special attention is given to the duration of the transient period as a function of the different kinetic parameters. The kinetic models developed are fitted to experimental data, either directly obtained by the authors or published in the literature. These general models have a broad range of application.info:eu-repo/semantics/publishedVersio

Polymerization of ethylene using metallocene and aluminoxane systems

This paper describes ethylene polymerization using a number of metal-locene and aluminoxane catalyst systems, Cp2MR2 and methylaluminoxane [M = Zr, W, Nb; R = Cl, CH3]. Two types of methylaluminoxane, MAO (1) and MAO (2), were used as cocatalysts. The polymerization activities of the complexes Cp2WCl2 and Cp2NbCl2 were compared with that of Cp2ZrCl2. The Nb and W complexes were found to be less active than the Zr complex. Polyethylene characterization was also carried out by the following methods: gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR).info:eu-repo/semantics/publishedVersio

Increase in ghrelin levels after weight loss in obese Zucker rats is prevented by gastric banding.

Obes Surg. 2007 Dec;17(12):1599-607. Epub 2007 Nov 30. Increase in ghrelin levels after weight loss in obese Zucker rats is prevented by gastric banding. Monteiro MP, Ribeiro AH, Nunes AF, Sousa MM, Monteiro JD, Aguas AP, Cardoso MH. Department of Anatomy and UMIB (Unit for Multidisciplinary Biomedical Research) of ICBAS (Abel Salazar Institute for the Biomedical Sciences), University of Porto, 4099-003 Porto, Portugal. [email protected] Abstract BACKGROUND: Gastric banding is thought to decrease appetite in addition to the mechanical effects of food restriction, although this has been difficult to demonstrate in human studies. Our aim was to investigate the changes in orexigenic signals in the obese Zucker rat after gastric banding. METHODS: Obese Zucker rats (fa/fa) were submitted to gastric banding (GBP), sham gastric banding fed ad libitum (sham), or sham operation with food restriction, pair-fed to the gastric banding group (sham-PF). Lean Zucker rats (fa/+) were used as additional controls. Body weight and food intake were daily recorded for 21 days after surgery when epididymal fat was weighed and fasting ghrelin and hypothalamic NPY mRNA expression were measured. RESULTS: Gastric banding in obese Zucker rats resulted in a significant decrease of cumulative body weight gain and food intake. Furthermore, gastric banded rats were leaner than Sham-PF, as expressed by a significantly lower epididymal fat weight. Ghrelin levels of gastric banded rats were not increased when compared to sham-operated animals fed ad libitum and were significantly lower than the levels of weight matched sham-PF rats (1116.9 +/- 103.3 g GBP vs 963.2 +/- 54.3 g sham, 3,079.5 +/- 221.6 sham-PF and 2,969.9 +/- 150.9 g lean rats, p < 0.001); hypothalamic NPY mRNA expression was not increased in GBP when compared to sham-operated rats. CONCLUSION: In obese Zucker rats, GBP prevents the increase in orexigenic signals that occur during caloric deprivation. Our data support the hypothesis that sustained weight loss observed after gastric banding does not depend solely on food restriction

Novel chromone and xanthone derivatives: synthesis and ROS/RNS scavenging activities

Chromones and xanthones are oxygen-containing heterocyclic compounds acknowledged by their antioxidant properties. In an effort to develop novel agents with improved activity, a series of compounds belonging to these chemical classes were prepared. Their syntheses involve the condensation of appropriate 2-methyl-4H-chromen-4-ones, obtained via Baker-Venkataraman rearrangement, with (E)-3-(3,4-dimethoxyphenyl)acrylaldehyde to provide the corresponding 2-[(1E,3E)-4-(3,4-dimethoxyphenyl)buta-1,3-dien-1-yl]-4H-chromen-4-ones. Subsequent electrocyclization and oxidation of these compounds led to the synthesis of 1-aryl-9H-xanthen-9-ones. After cleavage of the protecting groups, hydroxylated chromones and xanthones were assessed as scavenging agents against both reactive oxygen species (ROS) [superoxide radical (O2(•-)), hydrogen peroxide (H2O2), hypochlorous acid (HOCl), singlet oxygen ((1)O2), and peroxyl radical (ROO(•))] and reactive nitrogen species (RNS) [nitric oxide ((•)NO) and peroxynitrite anion (ONOO(-))]. Generally, all the tested new hydroxylated chromones and xanthones exhibited scavenger effects dependent on the concentration, with IC50 values found in the micromolar range. Some of them were shown to have improved scavenging activity when compared with previously reported analogues, allowing the inference of preliminary conclusions on the structure-activity relationship

2,3-Diarylxanthones as strong scavengers of reactive oxygen and nitrogen species: a structure–activity relationship study

Xanthones are a class of oxygen-containing heterocyclic compounds widely distributed in nature. The natural derivatives can present different substitutions in the xanthone core that include hydroxyl, methoxyl, prenyl and glycosyl groups. The inclusion of aryl groups has only been reported for a few synthetic derivatives, the 2,3-diaryl moiety being recently introduced by our group. Xanthones are endowed with a broad spectrum of biological activities, many of them related to their antioxidant ability, including the scavenging of reactive oxygen species (ROS) and reactive nitrogen species (RNS), as well as metal chelating effects. Considering the interesting and promising antioxidant activities present in compounds derived from the xanthone core, the main goal of this work was to evaluate the scavenging activity of the new 2,3-diarylxanthones for ROS, including superoxide radical (O2 ), hydrogen peroxide (H2O2), singlet oxygen (1O2), peroxyl radical (ROO ) and hypochlorous acid (HOCl), and RNS, including nitric oxide ( NO) and peroxynitrite anion (ONOO ). The obtained results revealed that the tested 2,3-diarylxanthones are endowed with outstanding ROS and RNS scavenging properties, considering the nanomolar to micromolar range of the IC50 values found. The xanthones with two catechol rings were the most potent scavengers of all tested ROS and RNS. In conclusion, the new 2,3-diarylxanthones are promising molecules to be used for their potential antioxidant properties