Efeitos imediatos da oscilação extra-torácica de alta frequência "THE VESTr", em pacientes críticos submetidos a ventilação mecânica

A retenção de secreções é um problema comum em pacientes sedados e ventilados invasivamente, estas são ponto de partida para o aparecimento de infecções, pneumonia nosocomial e agravamento geral do estado clínico do paciente. Apesar de estudos comprovarem a eficácia da fisioterapia respiratória convencional nestes doentes, outros demonstraram que é cara, operador dependente, de eficácia variada e por vezes causar desconforto e dor. Vários estudos que comprovaram a segurança e eficácia da Alta Frequência Oscilatória Extra Torácica serviram de base para a realização do estudo onde se avaliou os efeitos fisiológicos imediatos da aplicação da técnica e diferenças a médio e longo prazo na comparação entre dois grupos. O VestR força o ar para dentro e para fora dos pulmões aumentando a interacção fluxo/secreções reduzindo a sua viscosidade, ao libertar e mobilizar as secreções, estas são mais facilmente aspiradas, reduzindo o risco de infecção pulmonar. Dez pacientes que cumpriram critérios de inclusão entraram no estudo. Durante dois dias foi aplicado num dos grupos o VestR durante dez minutos, três vezes por dia. Foram registados os parâmetros ventilatórios, cardíacos e de oxigenação para avaliar efeitos fisiológicos imediatos. Para comparação de grupos foram efectuados registos durante as 48h dos parâmetros referidos anteriormente. No período de follow up foram registados os dias de internamento hospitalar na unidade de cuidados intensivos e os dias de ventilação mecânica invasiva. Pelo reduzido tamanho amostral foi usada a estatística descritiva para a análise dos dados. Não foram encontradas diferenças significativas entre os dois grupos, apesar de haver uma tendência de melhoria dos parâmetros fisiológicos imediatos durante a aplicação da técnica. Concluímos que, com a limitação do tamanho amostral, os efeitos positivos imediatos da aplicação da HFCWO neste grupo podem-se revelar um bom indício para a realização de estudos futuros, com tamanhos amostrais superiores e melhor controlados, que comprovem que é uma técnica mais vantajosa e eficaz para o tratamento dos doentes críticos.

Basic dyestuffs removal from textile effluents using feathers: equilibrium, kinetic and column studies

This research work has been focused in the study of gallinaceous feathers, a waste that may be valorised as sorbent, to remove the Dark Blue Astrazon 2RN (DBA) from Dystar. This study was focused on the following aspects: optimization of experimental conditions through factorial design methodology, kinetic studies into a continuous stirred tank adsorber (at pH 7 and 20ºC), equilibrium isotherms (at pH 5, 7 and 9 at 20 and 45ºC) and column studies (at 20ºC, at pH 5, 7 and 9). In order to evaluate the influence of the presence of other components in the sorption of the dyestuff, all experiments were performed both for the dyestuff in aqueous solution and in real textile effluent. The pseudo-first and pseudo-second order kinetic models were fitted to the experimental data, being the latter the best fit for the aqueous solution of dyestuff. For the real effluent both models fit the experimental results and there is no statistical difference between them. The Central Composite Design (CCD) was used to evaluate the effects of temperature (15 - 45ºC) and pH (5 - 9) over the sorption in aqueous solution. The influence of pH was more significant than temperature. The optimal conditions selected were 45ºC and pH 9. Both Langmuir and Freundlich models could fit the equilibrium data. In the concentration range studied, the highest sorbent capacity was obtained for the optimal conditions in aqueous solution, which corresponds to a maximum capacity of 47± 4 mg g-1. The Yoon-Nelson, Thomas and Yan’s models fitted well the column experimental data. The highest breakthrough time for 50% removal, 170 min, was obtained at pH 9 in aqueous solution. The presence of the dyeing agents in the real wastewater decreased the sorption of the dyestuff mostly for pH 9, which is the optimal pH. The effect of pH is less pronounced in the real effluent than in aqueous solution. This work shows that feathers can be used as sorbent in the treatment of textile wastewaters containing DBA.

Biofiltration of Air/Styrene and Air/Styrene/Acetone mixtures in a bubble column reactor

The goal of this work was the treatment of polluted waste gases in a bubble column reactor (BCR), in order to determinate the maximum value of reactor’s efficiency (RE), varying the inlet concentration (C in) of the pollutants. The gaseous mixtures studied were: (i) air with styrene and (ii) air with styrene and acetone. The liquid phase used to contain the biomass in the reactor was a basal salt medium (BSM), fundamental for the microorganisms’ development. The reactor used in this project consists of a glass column of 620mm height and inside diameter 75mm. In all essays there were continually measured: pH, dissolved oxygen and liquid’s temperature. Temperature and pH were controlled (T=24ºC, 7.0 ≤ pH ≤ 7.7). In all experiments the liquid volume (including the biomass) used in the reactor was kept constant (1.5L) as well as the total gas flowrate (1 L/min). Concerning the goal of the work, some parameters were calculated: the organic load (OL), removal efficiency (RE), elimination capacity (EC), biomass concentration (xf) and dry biomass concentration (Xdw). In a first series of experiments, the gas mixture used was air with styrene, varying its concentration from 191 mg.m-3 to 6500 mg.m-3.It was concluded that the RE maximum value (97%) was obtained for C in Sty = 4200 mg.m-3. For the maximum tested value of C in Sty, RE obtained was 20%. In a second step, the gaseous mixture included acetone, varying C in Sty between 225 mg.m-3 and 2659 mg.m-3 and C in Ac between 153mg.m-3 and 1389 mg.m-3. The aim of these tests was the determination of C in Ac for which RE was maximum, obtaining C in Ac = 750 mg.m-3. A third series of experiments was performed, in which C in Ac was maintained equal to that value and C in Sty was varied until higher values (5422 mg.m-3). RE maximum values obtained in this last series were 100% for styrene and 40% for acetone. One important conclusion is the fact that the microorganisms available degrade better styrene than acetone. On the ambit of this study, it was possible to identify the species available in biomass: Xanthobacter antotrophicus py2, Enterobacter aerogenes, Nocardia, Corynebacterium Spp., Rhodococcus rhodochrous e Pseudomonas Sp.

Copper, nickel and zinc removal by peanut hulls: batch and column studies in mono, tri-component systems and with real effluent

The main goal of this research study was the removal of Cu(II), Ni(II) and Zn(II) from aqueous solutions using peanut hulls. This work was mainly focused on the following aspects: chemical characterization of the biosorbent, kinetic studies, study of the pH influence in mono-component systems, equilibrium isotherms and column studies, both in mono and tri-component systems, and with a real industrial effluent from the electroplating industry. The chemical characterization of peanut hulls showed a high cellulose (44.8%) and lignin (36.1%) content, which favours biosorption of metal cations. The kinetic studies performed indicate that most of the sorption occurs in the first 30 min for all systems. In general, a pseudo-second order kinetics was followed, both in mono and tri-component systems. The equilibrium isotherms were better described by Freundlich model in all systems. Peanut hulls showed higher affinity for copper than for nickel and zinc when they are both present. The pH value between 5 and 6 was the most favourable for all systems. The sorbent capacity in column was 0.028 and 0.025 mmol g-1 for copper, respectively in mono and tri-component systems. A decrease of capacity for copper (50%) was observed when dealing with the real effluent. The Yoon-Nelson, Thomas and Yan’s models were fitted to the experimental data, being the latter the best fit.

Dimensionamento de muros de suporte considerando diferentes metodologias de cálculo

A presente dissertação consiste em verificar a tendência do coeficiente de segurança quando se varia certos parâmetros (ângulo de atrito interno do terreno, inclinação do terrapleno no tardoz do muro e o ângulo que a massa de solo faz quando se comporta como parte integrante do muro numa situação limite) considerados no cálculo. Para atingir os objectivos anteriormente referidos, dividiu-se o trabalho em duas fases, a primeira fase teve como objectivo verificar qual a tendência do coeficiente de segurança quando sujeito à variação de dois parâmetros, o ângulo de atrito interno do terreno e a inclinação do terrapleno no tardoz do muro que varia de 5° até ao valr do ângulo de atrito interno do terreno. A segunda fase consiste em analisar qual a tendência do coeficiente de segurança quando sujeito à variação de três parâmetros, o ângulo de atrito interno do terreno, de 20° a 45°, a inclinação do terrapleno no tardoz do muro, de 10° até ao valor do ângulo de atrito interno do terreno, e o ângulo que a massa de solo faz quando se comporta como parte integrante do muro numa situação limite. Para ambas as situações efectuaram-se os respectivos cálculos quer pela Teoria de Rankine e quer pela Teoria de Mohr – Coulomb, havendo casos em que foi necessário conjugar estas duas Teorias.

Fractional order modelling of zero length column desorption response for adsorbents with variable particle sizes

This manuscript analyses the data generated by a Zero Length Column (ZLC) diffusion experimental set-up, for 1,3 Di-isopropyl benzene in a 100% alumina matrix with variable particle size. The time evolution of the phenomena resembles those of fractional order systems, namely those with a fast initial transient followed by long and slow tails. The experimental measurements are best fitted with the Harris model revealing a power law behavior.

Practical software improve design and performance of a randomly packed air stripping column for removing volatile organic compounds from water

STRIPPING is a software application developed for the automatic design of a randomly packing column where the transfer of volatile organic compounds (VOCs) from water to air can be performed and to simulate it’s behaviour in a steady-state. This software completely purges any need of experimental work for the selection of diameter of the column, and allows a choice, a priori, of the most convenient hydraulic regime for this type of operation. It also allows the operator to choose the model used for the calculation of some parameters, namely between the Eckert/Robbins model and the Billet model for estimating the pressure drop of the gaseous phase, and between the Billet and Onda/Djebbar’s models for the mass transfer. Illustrations of the graphical interface offered are presented.

RuSe Electrocatalysts and Single Wall Carbon Nanohorns Supports for the Oxygen Reduction Reaction

Selenium modified ruthenium electrocatalysts supported on carbon black were synthesized using NaBH4 reduction of the metal precursor. Prepared Ru/C electrocatalysts showed high dispersion and very small averaged particle size. These Ru/C electrocatalysts were subsequently modified with Se following two procedures: (a) preformed Ru/carbon catalyst was mixed with SeO2 in xylene and reduced in H2 and (b) Ru metal precursor was mixed with SeO2 followed by reduction with NaBH4. The XRD patterns indicate that a pyrite-type structure was obtained at higher annealing temperatures, regardless of the Ru:Se molar ratio used in the preparation step. A pyrite-type structure also emerged in samples that were not calcined; however, in this case, the pyrite-type structure was only prominent for samples with higher Ru:Se ratios. The characterization of the RuSe/C electrocatalysts suggested that the Se in noncalcined samples was present mainly as an amorphous skin. Preliminary study of activity toward oxygen reduction reaction (ORR) using electrocatalysts with a Ru:Se ratio of 1:0.7 indicated that annealing after modification with Se had a detrimental effect on their activity. This result could be related to the increased particle size of crystalline RuSe2 in heat-treated samples. Higher activity of not annealed RuSe/C catalysts could also be a result of the structure containing amorphous Se skin on the Ru crystal. The electrode obtained using not calcined RuSe showed a very promising performance with a slightly lower activity and higher overpotential in comparison with a commercial Pt/C electrode. Single wall carbon nanohorns (SWNH) were considered for application as ORR electrocatalysts' supports. The characterization of SWNH was carried out regarding their tolerance toward strong catalyzed corrosion conditions. Tests indicated that SWNH have a three times higher electrochemical surface area (ESA) loss than carbon black or Pt commercial electrodes.

Recycling old screen-printed electrodes with newly designed plastic antibodies on the wall of carbon nanotubes as sensory element for in situ detection of bacterial toxins in water

Using low cost portable devices that enable a single analytical step for screening environmental contaminants is today a demanding issue. This concept is here tried out by recycling screen-printed electrodes that were to be disposed of and by choosing as sensory element a low cost material offering specific response for an environmental contaminant. Microcystins (MCs) were used as target analyte, for being dangerous toxins produced by cyanobacteria released into water bodies. The sensory element was a plastic antibody designed by surface imprinting with carefully selected monomers to ensure a specific response. These were designed on the wall of carbon nanotubes, taking advantage of their exceptional electrical properties. The stereochemical ability of the sensory material to detect MCs was checked by preparing blank materials where the imprinting stage was made without the template molecule. The novel sensory material for MCs was introduced in a polymeric matrix and evaluated against potentiometric measurements. Nernstian response was observed from 7.24 × 10−10 to 1.28 × 10−9 M in buffer solution (10 mM HEPES, 150 mM NaCl, pH 6.6), with average slopes of −62 mVdecade−1 and detection capabilities below 1 nM. The blank materials were unable to provide a linear response against log(concentration), showing only a slight potential change towards more positive potentials with increasing concentrations (while that ofthe plastic antibodies moved to more negative values), with a maximum rate of +33 mVdecade−1. The sensors presented good selectivity towards sulphate, iron and ammonium ions, and also chloroform and tetrachloroethylene (TCE) and fast response (<20 s). This concept was successfully tested on the analysis of spiked environmental water samples. The sensors were further applied onto recycled chips, comprehending one site for the reference electrode and two sites for different selective membranes, in a biparametric approach for “in situ” analysis.

Análise da atual unidade de desasfaltação pelo Propano para o tratamento de crudes não parafínicos

Este trabalho teve como principal objetivo o estudo da simulação da unidade de destilação atmosférica e a vácuo da fábrica de óleos base da Petrogal, permitindo verificar que, uma vez conseguido um modelo num programa de simulação que traduz o comportamento real de um dado processo, é possível sem riscos operacionais avaliar o efeito da alteração das condições normais de funcionamento desse processo. O trabalho foi orientado pelo Eng.º Carlos Reis, no que diz respeito à empresa, e pelo Prof. Dr. Luís Silva, pelo ISEP. O trabalho foi dividido em duas partes, sendo a primeira direcionada à obtenção do novo crude a partir de dois crudes pesados e caracterização dessa mistura. Já a segunda parte reside na refinação deste novo crude através da plataforma Aspen Plus para obtenção do resíduo de vácuo, para posterior processamento na coluna de discos rotativos usando um método de separação por extração liquido-liquido. Estudaram-se as propriedades físicas dos fluidos e verificou-se que na destilação atmosférica as curvas de destilação encontram-se muito próximas comparativamente com os resultados obtidos pela empresa, enquanto na destilação a vácuo os valores encontram-se mais afastados, apresentando uma variação de 30ºC a 100ºC em relação aos valores obtidos pelo Petro-Sim. Com a finalidade de cumprir um dos objetivos em falta, irão ser realizadas futuramente simulações no extrator de discos rotativos para otimização do processo para crudes pesados, sendo os resultados facultados, posteriormente, à Petrogal. Durante a realização do trabalho foi atingido um modelo real representativo da unidade de destilação atmosférica e a vácuo da Petrogal, podendo obter-se resultados para qualquer tipo de crude, fazendo apenas variar o assay da corrente de alimentação.