Aplicação computacional para o cálculo das canalizações eléctricas segundo as RTIEBT

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Energia). Faculdade de Engenharia. Universidade do Porto. 201

Chemical characterization of pine bark (Pinus pinaster Aiton subsp. atlantica), antioxidant properties and phenolic profile of its extracts

Introduction: Pine bark is an agroindustrial residue from the timber industry and represents a source of phenolic compounds. These compounds have several beneficial properties being antioxidants, antimicrobial, anti-inflammatory, cardiovascular, among others. Objetives: The aim of this work was to study the chemical composition of the bark from Pinus pinaster Aiton subsp. atlantica and the phenolic profile of its aqueous, ethanolic and hydroethanolic extracts. Methods: The moisture content, ash, protein, crude fat and carbohydrates were analysed. The bark was extracted with water, ethanol or a mixture of both in a Soxhlet apparatus and the extraction yield, total phenolic content (TPC), antioxidant activity and phenolic profile by RP-HPLC-UV, in the extracts with higher TPC, were determined. Results: The results obtained for chemical composition were: 63.43 of carbohydrates, 2.81 of crude fat, 1.60 of proteins and 1.75 of ash, calculated in % w/w of dry bark. The extraction yield was greater for the ethanolic and the hydroethanolic extracts (17.08 and 17.55% w/w dry bark, respectively). The TPC and antioxidant activity were higher in the hydroethanolic extract (73.48 mg GAE/g and 108.74 mg AAE/g dry bark, respectively). Regarding the phenolic profile of the hydroethanolic extract, gallic acid, taxifolin, ferulic acid and quercetin were identified at 280 nm, and catechin was identified in the ethanolic extract at 320 nm. Conclusion: P. pinaster Aiton subsp. atlantica bark is mainly constituted by carbohydrates and it is rich in hydroethanolic and ethanolic extractives, being that these have high antioxidant activity. The ethanolic extract presents higher catechin amount when compared to the hydroethanolic extract.info:eu-repo/semantics/publishedVersio

Impact of grape pectic polysaccharides on anthocyanins thermostability

The impact of grape pectic polysaccharides on malvidin-3-O-β-d-glucoside thermostability was evaluated in model solutions. Pectic polysaccharides richer in homogalacturonan domains, with less neutral sidechains (chelator fraction) showed higher binding with malvidin-3-O-β-d-glucoside, by 1H NMR (Ka=505 M-1). Binding affinity with water soluble extract was estimated to be 10-fold lower, possibly due to the presence of neutral branched regions and more compacted structure, hampering the binding. Hydrophobic domains, such as rhamnogalacturonans-I domains in acid soluble polysaccharides, may participate in the formation of complexes with malvidin-3-O-β-d-glucoside. The thermostability of anthocyanin-polysaccharides complexes was evaluated at different temperatures, assessing anthocyanins degradation by HPLC-DAD. Polysaccharides showed to improve anthocyanin thermostability, with chelator and acid extract having the highest impact at lowest temperatures. Electrostatic interactions, additionally stabilized by hydrophobic effect contribute to the anthocyanin-polysaccharides binding and to the consequent thermostabilization. The protection provided by grape pectic polysaccharides foresees innovative anthocyanin food products with improved thermostability and colour features.publishe

Comparison of milk from two different cow breeds Barrosã and Frísia

Milk from two different cow breeds, Barrosã and Frísia, was studied. Within the same breed five and four milk samples were taken respectively for chemical and microbiological analysis. The following chemical parameters were analysed in triplicate: Total Fat, Fatty Acids Identification and Quantification, Protein, Casein, Albumin, Non-protein Nitrogen, Vitamin A, Vitamin D, Phosphorus, Potassium, Sodium, Iron, Magnesium, Calcium, Ash, Total solids, Lactic acid and Acidity. In general terms milk from Barrosã breed showed higher values for all analysed parameters except for Total Fat, Total Solids and Vitamin D. Statistical analysis, by testing the chemical parameters all together using the Hotelling T2 test showed that milk samples from the two cow breeds were significantly different (α=0,05). Microbiological analysis (Total Viable Counts (30ºC), Escherichia coli, Staphylococcus coagulase + and Listeria monocytogenes) was also performed. Staphylococcus coagulase + was found in one milk sample from Barrosã breed. Listeria monocytogenes was found in two milk samples from Frísia breed

Comportamento em crianças do 1.º ciclo: relação com o processamento sensorial e o tempo de exposição a ecrãs

Introdução: As alterações do comportamento podem estar associadas tanto com disfunções do processamento sensorial, como com o tempo de exposição a ecrãs. Objetivo: Verificar se o processamento sensorial e o tempo de exposição a ecrãs em crianças em idade escolar do 1.º ciclo influenciam os seus comportamentos. Método: Utilizou-se um questionário sociodemográfico, a Medida do Processamento Sensorial e o Questionário de Capacidades e Dificuldades. A amostra foi composta por 183 crianças entre os seis e os 10 anos. Para o tratamento de dados utilizou-se medidas de estatística descritiva para caraterizar a amostra e descrever as frequências das variáveis, para relacionar o processamento sensorial com o comportamento, e o tempo de exposição a ecrãs com o comportamento utilizou-se a correlação não paramétrica de Spearman, e para verificar se o tempo de exposição a ecrãs e o processamento sensorial são preditores do comportamento realizou-se uma regressão linear múltipla. Resultados: As variáveis que se revelaram preditoras do comportamento foram ao nível do processamento sensorial, a participação social (Beta = 0,255, p < 0,001), a consciência do corpo (Beta = 0,324, p < 0,001) e a audição (Beta = 0,164, p = 0,018), tendo sido apurada a tendência para quanto mais os problemas no processamento sensorial mais os problemas de comportamento. Da análise entre as variáveis, tempo de exposição a ecrãs e comportamento não se verificou nenhuma correlação significativa. Conclusão: Conclui-se que dificuldades no processamento sensorial estão associadas a uma maior prevalência de problemas de comportamento, em crianças com desenvolvimento típico.Introduction: Behavioral changes may be associated with sensory processing disorders as well as the time of screen exposure. Objective: To verify if sensory processing and exposure time to screens in primary school-age children influences their behavior. Method: A sociodemographic questionnaire, the Sensory Processing Measure and the Strengths and Difficulties Questionnaire were used. The sample consisted of 183 children aged between six and ten years old. For data processing were used descriptive statistical measures to characterize the sample and describe the frequencies of variables, to relate sensory processing to behavior, and the time of exposure to screens with behavior, we used the non-parametric correlation of Spearman, and finally, to verify whether the time of exposure to screens and sensory processing are predictors of children's behavior, was carried out a multiple linear regression. Results: The variables that proved to be predictors of behavior were at the level of sensory processing, social participation (Beta = 0.255, p < 0.001), body awareness (Beta = 0.324, p < 0.001) and hearing (Beta = 0.164, p = 0.018), a trend was observed in which behavioral problems increase as the sensory processing problems increased. From the analysis between the time of exposure to screens and behavior variables, no significant correlation was found. Conclusion: It is concluded that sensory processing difficulties are associated with a higher prevalence of behavior problems in typically developing children.info:eu-repo/semantics/publishedVersio

Enhancing storage stability of smoke-flavored horse mackerel filets using natural extracts as preservatives

The Atlantic horse mackerel (Trachurus trachurus) is a globally favored fish due to its abundance, nutritional value, and affordability, but it faces quality preservation challenges. To address this, this study aimed to enhance its value by creating low-salt smoked products with natural bioactive compounds from seafood and forest sources. The fish filets were divided into four groups: one as a control, and the others were treated with various bioactive extract solutions, specifically pine bark, mussels, and microalgae. After 15 days of storage at 4°C, significant differences in properties were observed. Moisture and salt had an inverse relationship, with decreasing moisture and pH over time. Oxidation levels remained acceptable, although sensory quality was affected by storage. Microbiological analysis uncovered high contamination levels in certain samples at specific points in time, although no pathogens such as Salmonella spp. or Listeria monocytogenes were detected. While microalgae extract was the most powerful antioxidant, its performance was hampered by the poor sensory scores. On the other hand, pine bark extract was the most acceptable from a sensory point of view and revealed some antimicrobial inhibition. Using natural antioxidants provides an appealing solution for consumers seeking products with clean labels

Coupling between Hydrodynamics and Chlorophyll <i>a</i> and Bacteria in a Temperate Estuary: A Box Model Approach

The spatial patterns of chlorophyll a and bacteria were assessed in a temperate Atlantic tidal estuary during seasonal surveys, as well as in consecutive summer spring and neap tides. A box model approach was used to better understand spatial and temporal dynamics of these key estuarine descriptors. The Lima estuary (NW Portugal) was divided into boxes controlled by salinity and freshwater discharge and balance equations were derived for each variable, enabling the calculation of horizontal and vertical fluxes of plankton and, therefore, production or consumption rates. Chlorophyll a tended to burst within the oligohaline zone, whereas higher counts of bacteria were found in the mesohaline stretch. Whenever the water column was stratified, similar tide-independent trends were found for chlorophyll a and bacterial fluxes, with net growth in the upper less saline boxes, and consumption beneath the halocline. In the non-stratified upper estuary, other controls emerged for chlorophyll a and bacteria, such as nitrogen and carbon inputs, respectively. The presented results show that, while tidal hydrodynamics influenced plankton variability, production/consumption rates resulted from the interaction of additional factors, namely estuarine geomorphological characteristics and nutrient inputs. In complex estuarine systems, the rather simple box model approach remains a useful tool in the task of understanding the coupling between hydrodynamics and the behavior of plankton, emerging as a contribution toward the management of estuarine systems

The Chemical Characterisation of the Maritime Pine Bark Cultivated in Northern Portugal

Maritime pine, scientifically known as Pinus pinaster, holds a vital role in Iberian Peninsula forests, primarily as a source of wood for panels, paper, and cellulose production. Recently, there has been a growing interest in utilising agroforestry by-products to yield valuable chemicals for applications in various sectors, including the food, pharmaceutical, and bioenergy industries. This study aimed to assess the value of the primary by-product of Pinus pinaster from the Minho region of northwestern Portugal, i.e., the bark. The research extensively examined the bark’s chemical and thermal characteristics, including ash content, extractives, lignin, cellulose, hemicellulose, fatty acids, and mineral composition. Additionally, various analytical techniques like FTIR, SEM, DSC, DTG, and XRD were used to observe chemical structure differences. The results reveal that the Pinus pinaster bark primarily consists of lignin (51.15%) and holocellulose (46.09%), with extractives mainly soluble in toluene–ethanol, followed by water, and a small amount of them are soluble in ethanol. The bark contained around 0.44% ash, and heavy metals such as Cd and Pb were not found. During degradation, Pinus pinaster experienced a 10% mass loss at 140 °C. In terms of crystallinity, holocellulose and cellulose showed similar percentages at approximately 25.5%, while α-cellulose displayed the highest crystallinity index at 41%

The Chemical Characterisation of the Maritime Pine Bark Cultivated in Northern Portugal

2023 Descuento MDPIMaritime pine, scientifically known as Pinus pinaster, holds a vital role in Iberian Peninsula forests, primarily as a source of wood for panels, paper, and cellulose production. Recently, there has been a growing interest in utilising agroforestry by-products to yield valuable chemicals for applications in various sectors, including the food, pharmaceutical, and bioenergy industries. This study aimed to assess the value of the primary by-product of Pinus pinaster from the Minho region of northwestern Portugal, i.e., the bark. The research extensively examined the bark’s chemical and thermal characteristics, including ash content, extractives, lignin, cellulose, hemicellulose, fatty acids, and mineral composition. Additionally, various analytical techniques like FTIR, SEM, DSC, DTG, and XRD were used to observe chemical structure differences. The results reveal that the Pinus pinaster bark primarily consists of lignin (51.15%) and holocellulose (46.09%), with extractives mainly soluble in toluene–ethanol, followed by water, and a small amount of them are soluble in ethanol. The bark contained around 0.44% ash, and heavy metals such as Cd and Pb were not found. During degradation, Pinus pinaster experienced a 10% mass loss at 140 °C. In terms of crystallinity, holocellulose and cellulose showed similar percentages at approximately 25.5%, while α-cellulose displayed the highest crystallinity index at 41%.Foundation for Science and Technology (Portugal)Center for Research and Development in Agrifood Systems and SustainabilitySusTECMinisterio de Ciencia, Innovación y Universidades (España)European CommissionDepto. de Farmacología y ToxicologíaFac. de FarmaciaTRUEpubDescuento UC