8 resultados para Nonlinear correlation coefficients

em Instituto Politécnico do Porto, Portugal


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A multiresidue gas chromatographic method for the determination of six fungicides (captan, chlorthalonil, folpet, iprodione, procymidone and vinclozolin) and one acaricide (dicofol) in still and fortified wines was developed. Solid-phase microextraction (SPME) was chosen for the extraction of the compounds from the studied matrices and tandem mass spectrometry (MS/MS) detection was used. The extraction consists in a solvent free and automated procedure and the detection is highly sensitive and selective. Good linearity was obtained with correlation coefficients of regression (R2) > 0.99 for all the compounds. Satisfactory results of repeatability and intermediate precision were obtained for most of the analytes (RSD < 20%). Recoveries from spiked wine ranged from 80.1% to 112.0%. Limits of quantification (LOQs) were considerably below the proposedmaximumresidue limits (MRLs) for these compounds in grapes and below the suggested limits for wine (MRLs/10), with the exception of captan.

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Neste trabalho estudou-se a implementação de um sistema de vigilância e alerta da qualidade da água de um recurso hídrico, para um possível caso de poluição. Em 25 de Agosto de 2008 foram derramadas 4 toneladas de ácido clorídrico acidentalmente para as águas do rio Febros. Este rio situa-se no concelho de Vila Nova de Gaia e é um pequeno afluente do rio Douro, tendo cerca de 14 km de extensão e tem a particularidade de atravessar o Parque Biológico de Gaia. A falta de uma rápida intervenção e da existência de um plano de ação levou a que parte da fauna e flora fosse destruída. Por este motivo realizou-se este estudo que se baseou na criação de um sistema de vigilância e alerta a ser implementado neste rio. A informação da hidrogeometria do rio e da capacidade de transporte e dispersão de poluentes é indispensável para o bom funcionamento deste sistema. O coeficiente de dispersão longitudinal é um parâmetro muito importante no estudo da qualidade da água. Recorreu-se à utilização da Rodamina WT como marcador, determinando assim a evolução da sua concentração ao longo do tempo e espaço. No cálculo do coeficiente de dispersão foi utilizado o modelo Transient Storage, que demonstrou ser um bom modelo de ajuste aproximando-se dos valores medidos em campo. Para três estações diferentes com distâncias de 290, 390 e 1100 metros do ponto de injeção, obtiveram-se valores de coeficiente de dispersão de 0,18, 0,15 e 0,39 m2/s respetivamente. Os valores do ajuste expressos sob a forma de coeficiente de correlação foram 0,988, 0,998 e 0,986, para a mesma ordem de estações. A constante de rearejamento do rio foi também determinada recorrendo ao método dos marcadores inertes, utilizando o propano como marcador gasoso. A constante determinada próximo de Casal Drijo, entre 2 estações de amostragem a 140 e 290 m do local de injeção, foi de 13,4 dia-1. Com os resultados do coeficiente de dispersão e da constante de rearejamento para além da velocidade e caudal da corrente do rio conseguir-se-á construir o modelo de simulação e previsão de um possível poluente. O sistema de vigilância a implementar sugere-se assim que seja construído por duas partes, uma de análise de evolução da nuvem de poluição e plano de ação outra de monitorização contínua e emissão de alerta. Após uma análise do investimento à implementação deste sistema chegou-se à conclusão que o valor de investimento é de 15.182,00 €.

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The present work describes a solid-phase microextraction (SPME) gas chromatography_tandem mass spectrometry (MS/MS) method to quantify 24 pesticides in fortified white wine and fortified red wine. In this study “fortified wine” refers to a wine in which fermentation is arrested before completion by alcohol distillate addition, allowing sugar and alcoholic contents to be higher (around 80-100 g/L total sugars and 19-22% alcohol strength (v/v)). The analytical method showed good linearity, presenting correlation coefficients (R2) ≥ 0.989 for all compounds. Limits of detection (LOD) and quantitation (LOQ) in the ranges of 0.05-72.35 and 0.16-219.23 μg/L, respectively, were obtained. LOQs are below the maximum residue levels (MRL) set by European Regulation for grapes. The proposed method was applied to 17 commercial fortified wines. The analyzed pesticides were not detected in the wines tested.

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New chlorpromazine selective electrodes with a tubular arrangement and no internal reference solution are proposed. Selective membranes are of poly(vinyl chloride) (PVC) with the tetraphenylborate•chlorpromazine (TPB•CPZ) ion-exchanger dissolved in o-nitrophenyl octyl ether (oNPOE). Analytical features of the electrodes were evaluated on a single-channel flow assembly having 500 µl injection volumes and flow-rates of 4.5 ml min−1. For a carrier solution of 3.3×10−3Min sodium sulphate, Nernstian responsewas observed over the concentration range 1.0×10−5 to 1.0×10−2 M. Average slopes were about 59mVdecade−1 and squared correlation coefficients were >0.9984. Slight hiper-Nernstian behaviour was observed in buffer solutions of 4.4 pH; average slopes were of 62.06mVdecade−1. The electrode displayed a good selectivity for CPZ, with respect to, several foreign inorganic and organic species. The selective electrodes were successfully applied to the analysis of pure solutions and pharmaceutical preparations. Proposed method allows the analysis of 84 samples h−1, producing wastewaters of low toxicity. The proposed method offers the advantage of simplicity, accuracy, applicability to coloured and turbid samples, and automation feasibility.

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A promoção de competências de leitura é um tema central, tanto na educação regular, como na educação especial em crianças em idade pré-escolar e escolar. Todavia, as competências de leitura de indivíduos adultos com incapacidade intelectual são um domínio muito pouco estudado. São também escassos os estudos direcionados à avaliação dessas competências. Esta investigação propõe uma tradução/ adaptação do APAR (Assessment of Phonological Awareness and Reading), um protocolo de avaliação da consciência fonológica (CF) e da leitura especificamente concebido para a população em estudo. Procura-se também analisar os processos cognitivos envolvidos na leitura nos quais a intervenção produzirá resultados mais significativos e confirmar uma relação positiva entre a avaliação prévia de competências escolares em contexto formativo profissional e o efetivo desenvolvimento de competências de leitura. Foram avaliadas em dois momentos (pré e pós-teste) a CF e competências de leitura de 12 adultos com incapacidade intelectual ligeira, sendo estes sujeitos a um programa de intervenção, visando áreas menos desenvolvidas das suas competências que possibilitassem desempenhos de leitura mais fortes. Ao nível da análise quantitativa, foram comparados os resultados obtidos nos dois momentos de administração. No tratamento estatístico recorreu-se a análises de correlação de Spearman para determinar a presença de indicadores de desempenho ao nível da CF e ao cálculo de coeficientes de correlação de Pearson e Spearman para controlar variáveis externas como idade, sexo e habilitações literárias. Os resultados obtidos revelam desempenhos fracos ao nível da leitura/ compreensão textual e, em particular, da CF em pré-teste e ganhos significativos globais após implementação de uma intervenção baseada em medidas de avaliação prévia de competências de leitura/compreensão e CF

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Carbamate compounds are an important group of cholinesterase inhibitors. There is a need for creating awareness regarding the risks of the inadequate carbamate use in the residential areas due to potential adverse human effects. Carbaryl is a commonly used pesticide worldwide. A simple, fast, and high throughput method was developed employing liquid chromatography with fluorescence detector to determine carbaryl residues in rat feces. The extraction was performed by using a rapid, easy, cheap, effective, reliable, and safe (QuEChERS) method, using acetonitrile as the extracting solvent. The parameters for the performance of the extraction method were optimized, such as ratio of mass of sample per volume of extraction solvent, QuEChERS content, and cleanup columns. Linear response was obtained for all calibration curves (solven and matrix-matched) over the established concentration range (5 500 mg/L) with a correlation coefficients higher than 0.999. The achieved recovery was 97.9% with relative standard deviation values of 1.1% (n D 4) at 167 mg/kg fortified concentration level and the limits of detection and quantification were 27.7 and 92.3 mg/kg respectively.

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Purpose: The studies on links between sustainability, innovation, and competitiveness have been mainly focused at organizational and business level. The purpose of this research is to investigate if there is a correlation between these three variables at country level. Using international well recognized rankings of countries sustainability, innovation, and competitiveness, correlation analysis was performed allowing for the conclusion that there are indeed high correlations (and possible relationships) between the three variables at country level. Design/methodology/approach: Sustainability, innovation, and competitiveness literature were reviewed identifying a lack of studies examining these three variables at country level. Three major well recognized indexes were used to support the quantitative research: The World Economic Forum (2013) Sustainability-adjusted global competitiveness index, the Global Innovation Index (2014) issued by Cornell University, INSEAD, and WIPO and the IMD World Competitiveness Yearbook (2014). After confirming the distributions normality, Pearson correlation analysis was made with results showing high linear correlations between the three indexes. Findings: The results of the correlation analysis using Pearson correlation coefficient (all correlation coefficients are greater than 0.73) give a strong support to the conclusion that there is indeed a high correlation (and a possible relationship) between social sustainability, innovation and competitiveness at country level. Research limitations/implications: Further research is advisable to better understand the factors that contribute to the presented results and to establish a global paradigm linking these three main constructs (social sustainability, innovation, and competitiveness). Some authors consider that these measurements are not fully supported (e.g. due to different countries standards), however, it is assumed these differing underlying methodological approaches, by being used in conjunction, can be considered as a set of reliable and useful performance indicators. Practical implications: The results highlight the simultaneous relationship between social sustainability, innovation and competitiveness superior performance and the need to take that these considerations into business and operating models. Social implications: This research suggests that sustainability and innovation policies, strategies and practices are relevant for countries competitiveness and should be promoted particularly in countries ranked low on sustainability and innovation global scoring indexes. Originality/value: This is one of the few studies addressing the relationships between sustainability, innovation and competitiveness at country level.

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This study aimed to carry out experimental work to obtain, for Newtonian and non-Newtonian fluids, heat transfer coefficients, at constant wall temperature as boundary condition, in fully developed laminar flow inside a helical coil. The Newtonian fluids studied were aqueous solutions of glycerol, 25%, 36%, 43%, 59% and 78% (w/w) and the non-Newtonian fluids aqueous solutions of carboxymethylcellulose (CMC), a polymer, with concentrations 0.1%, 0.2%, 0.3%, 0.4% and 0.6% (w/w) and aqueous solutions of xanthan gum (XG), another polymer, with concentrations 0.1% and 0.2% (w/w). According to the rheological study performed, the polymer solutions had shear thinning behavior and different values of elasticity. The helical coil used has internal diameter, curvature ratio, length and pitch, respectively: 0.004575 m, 0.0263, 5.0 m and 11.34 mm. The Nusselt numbers for the CMC solutions are, on average, slightly higher than those for Newtonian fluids, for identical Prandtl and generalized Dean numbers. As outcome, the viscous component of the shear thinning polymer tends to potentiate the mixing effect of the Dean cells. The Nusselt numbers of the XG solutions are significant lower than those of the Newtonian solutions, for identical Prandtl and generalized Dean numbers. Therefore, the elastic component of the polymer tends to diminish the mixing effect of the Dean cells. A global correlation, for Nusselt number as a function of Péclet, generalized Dean and Weissenberg numbers for all Newtonian and non-Newtonian solutions studied, is presented.