XVI Congresso da Associação Portuguesa de Investigação Operacional: livro de resumos

Fundação para a Ciência e a Tecnologia - FC

Quantitation of absolute 2H enrichment of plasma glucose by 2H NMR analysis of its monoacetone derivative

A simple 2H NMR method for quantifying absolute 2H-enrichments in all seven aliphatic positions of glucose following its derivatization to monoacetone glucose is presented. The method is based on the addition of a small quantity of 2H-enriched formate to the NMR sample. When the method was applied to [2-2H]monoacetone glucose samples prepared from [2-2H]glucose standards of known enrichments in the range of 0.2-2.5%, enrichment estimates derived by the NMR method were in good agreement with the real enrichment values of the [2-2H]glucose precursors. The measurement was also applied to monoacetone glucose derived from human plasma glucose samples following administration of 2H2O and attainment of isotopic steady state, where glucose H2 and body water enrichment are equivalent. In these studies, the absolute H2 enrichment of plasma glucose estimated by the formate method was in good agreement with the 2H-enrichment of body water measured by an independent method. Magn Reson Med 48:535-539, 2002. © 2002 Wiley-Liss, Inc

Nanofiltration of Cork Wastewaters and Their Possible Use in Leather Industry as Tanning Agents

Cork processing wastewater is a very complex mixture of vegetal extracts and has, among other natural compounds, a very high content of phenolic/tannic colloidal matter that is responsible for severe environmental problems. In the present work, the concentration of this wastewater by nanofiltration was investigated with the aim of producing a cork tannin concentrate to be utilized in tanning. Permeation results showed that the permeate fluxes are controlled by both osmotic pressure and fouling/gel layer phenomena, leading to a rapid decrease of permeate fluxes with the concentration factor. The rejection coefficients to organic matter were higher than 95%, indicating that nanofiltration has a very good ability to concentrate the tannins and produce a permeate stream depleted from organic matter. The cork tannin concentrate obtained by nanofiltration and evaporation had total solids concentration of 34.8 g/l. The skins tanned by this concentrate were effectively converted to leather with a shrinking temperature of 7 degrees C

Structural study of the interaction of vanadate with the ligand 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmpp) in aqueous solution

The interaction of vanadate with the ligand 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmpp) was studied in aqueous solution using a combination of multinuclear NMR and EPR spectroscopies, as well as potentiometry and cyclic voltammetry. The different species in solution were identified and characterized, and their pKa values and stability constants determined. The vanadium complexes formed in solution are strongly dependent on media composition (ionic strength, presence of buffer), pH and metal-to-ligand ratio (M:L). Two major species -- V(V)/dmpp and V(V)/(dmpp)2 -- are formed in a 140 mM NaCl solution within the pH range 4.5 to 9.0, when M:L=1:2. In the presence of excess ligand (M:L<=1:5), only the 1:2 complex is present, and at pH<4 paramagnetic species are detected by EPR in solution, thus indicating a reducing capacity of the ligand. Cyclic voltammetry shows that redox processes in solution are not just electron transfer, but are accompanied by chemical reactions. The pKa values and stability constants were determined both by 51V NMR spectroscopy and potentiometry. The present results have a particular interest in the understanding of the aqueous solution chemistry in aerobic conditions of bis(1,2-dimethyl-3-hydroxy-4-pyridinonato) oxovanadium(IV) complex, VO(dmpp)2, a vanadium compound with potential insulin-mimetic properties.http://www.sciencedirect.com/science/article/B6TGG-40X8DKT-3C/1/3226f220763b348a4f3d74ae0fcd0e2

Performance das empresas familiares versus não familiares da Região do Alto Douro Vinhateiro

Este trabalho tem como principal objetivo analisar o desempenho das empresas familiares (EF), comparativamente com as não familiares (EnF), do setor agroindustrial, nomeadamente do setor vinhateiro. Embora existam diversos estudos sobre empresas familiares, a sua governance e performance, não existem estudos sobre o setor agroindustrial ligado à vitivinicultura e produção de vinho e as regiões, em Portugal. Na Região do Alto Douro Vinhateiro (RADV), que é particularmente representativa da paisagem que caracteriza a vasta Região Demarcada do Douro, predominam as EF. Definiu-se assim como perguntas de investigação: as EF localizadas na RADV, que exercem como atividade principal a viticultura e a produção de vinhos licorosos, ostentam um desempenho económico-financeiro superior às EnF? Que fatores explicam este desempenho? Recorrendo ao modelo de regressão linear, utilizando dados económico-financeiros obtidos da base de dados SABI (Sistema de Análise de Balanços Ibéricos), no período de 2012 a 2017, e dados não financeiros (tais como, profissionalização da gestão, CEO, sucessão de gerações, participação de membros da família no conselho de gestão, etc.), procurou-se determinar o poder explicativo das variáveis financeiras e não financeiras no desempenho económico-financeiro das EF e EnF. Utilizou-se um questionário para obter as informações não financeiras das empresas em estudo realizado no período compreendido entre 8 de agosto e 17 de dezembro de 2019. A amostra do estudo é composta por 115 EF e 33 EnF, maioritariamente dos municípios dos distritos de Vila Real e Viseu. Estudou-se a performance recorrendo a variáveis como o ROA, ROE, FCF e EVA®. Como fatores explicativos considerou-se variáveis financeiras (a estrutura do endividamento não corrente, rotação do ativo, valor acrescentado bruto, autonomia financeira, estrutura do ativo não corrente, liquidez geral e os gastos financeiros de financiamento) e não financeiras acima referidas. Concluiu-se, através da análise ao desempenho económico-financeiro que, durante o período analisado, as EF da RADV, tendem em média, a apresentar melhor desempenho económico e financeiro comparativamente às não familiares, confirmando as previsões iniciais.info:eu-repo/semantics/publishedVersio

Endodontic and Orthodontic Management of Traumatically Intruded Teeth with Horizontal Root Fracture: A Case Report

This report describes the case of an 8-year-old boy that was referred to endodontic and orthodontic treatment after suffering an injury that led to intrusion of the maxillary right permanent central incisor, palatal displacement of the upper right lateral incisor, and root fracture of both central incisors. Both injured teeth were immature and had open apices. The intruded tooth was repositioned by endodontic and orthodontic management. Endodontic therapy was performed in both teeth with periodical changes of calcium-hydroxide-based paste as root canal dressing and introduction of MTA as an apical barrier. The postoperative course was uneventful with clinical and radiographic success up to 3 and 1/2 years of follow up. In the present case, orthodontic repositioning combined with endodontic therapy constitued a viable alternative treatment for intrusive luxations in immature permanent teeth