Processos Oxidativos Avançados para Remediação de Águas Contaminadas por Pesticidas

Este trabalho teve como objectivo inicial o estudo de processos oxidativos avançados de forma a remediar e tratar águas contaminadas por pesticidas. No entanto, ao longo do trabalho experimental, constatou-se que os produtos resultantes da degradação de pesticidas são muitas vezes mais tóxicos do que os compostos que lhes deram origem e que, por isso, degradar um composto nem sempre é o melhor para o ambiente. Assim, neste trabalho, procurou-se estudar o processo de degradação com o objectivo de minimizar o impacto ambiental dos pesticidas na água e no ambiente em geral. A parte experimental deste trabalho foi dividida em duas etapas, sendo que, em ambas, a voltametria de onda quadrada e a espectrofotometria de UV/Vis foram os métodos de análise utilizados, para acompanhar o processo de fotodegradação. Na primeira etapa estudou-se a relação entre a estrutura química dos pesticidas MCPA, MCPP, 2.4-D e Dicloroprop e a sua fotodegradação. Soluções aquosas dos pesticidas enunciados foram submetidas a irradiação UV/vis, com incrementos variáveis de tempo de irradiação. Os resultados obtidos, nesta etapa, permitiram constatar diferenças na percentagem de degradação dos diferentes pesticidas. Dos pesticidas estudados verificou-se uma maior fotodegradação para o MCPA e MCPP seguido do Dicloroprop e finalmente o 2.4-D que se degradou menos. Os dados obtidos sugerem que a fotodegradação destes pesticidas está intimamente ligada com a estrutura das moléculas. A presença de um maior número de grupos cloro ligados ao anel aromático nos pesticidas 2,4-D e Dicloroprop faz com que estes sejam mais estáveis e por isso se degradam menos que o MCPA e o MCPP. Por outro lado, o facto de o 2,4-D apresentar um potencial de oxidação mais elevado do que o Dicloroprop, faz com que este seja mais difícil de degradar, o que justifica a diferença entre os dois. Desta forma, foi possível concluir que a estrutura dos pesticidas condiciona o processo de degradação, como esperado. Na segunda etapa, estudou-se a estabilização dos pesticidas MCPA e MCPP após encapsulação, com 2-hidroxipropil-β-ciclodextrina (HP-β-CD), em água desionizada e em água do rio. Para tal, submeteram-se as soluções aquosas dos pesticidas com e sem ciclodextrina, a irradiação UV/vis, também com incrementos variáveis de tempo. No caso do MCPA verificou-se que, tanto para água desionizada como para água do rio, que este herbicida encapsulado se degrada bastante menos do que o MCPA livre. O encapsulamento permitiu reduzir quase para metade a taxa de fotodegradação. Assim, confirmou-se que a HP-β-CD permite estabilizar este pesticida, tornando-o mais resistente à fotodegradação. Desta forma, originam-se menos produtos de degradação, os quais podem ser mais tóxicos, e reduz-se de o impacto ambiental deste herbicida. Verificou-se também que o MCPA livre se degrada mais em água do rio do que em água desionizada, provavelmente devido à matéria orgânica presente nesta água, que promove o processo de degradação. No que respeita ao MCPP também se constatou que este herbicida se degrada menos encapsulado do que livre, em água desionizada e em água do rio. Neste caso, conseguiu-se reduzir pouco a taxa de fotodegradação, mas, ainda assim se verifica uma estabilização deste pesticida através do encapsulamento. No entanto, tornou-se mais evidente a estabilização do MCPP após encapsulação em água do rio, já que apresenta uma taxa de fotodegradação menor. Este facto demonstra que a HP-β-CD permite estabilizar também este pesticida, tornando-o mais resistente à fotodegradação, e reduzindo seu impacto ambiental.

Articulação Ciência-Sociedade através do património artístico local : atividades e recursos didáticos centrados no Museu Cargaleiro

A educação em ciências com orientação Ciência-Tecnologia-Sociedade (CTS) centra-se no reconhecimento da capacidade da ciência para o desenvolvimento de uma sociedade assente nos valores da democracia. Esta orientação implica mais do que ensino de conteúdos estritamente disciplinares. O património artístico construído pode ser fonte inspiradora para o enriquecimento curricular proporcionando aprendizagens ativas e integradas. Foi nesta linha que definimos como objetivo desenvolver, implementar e validar atividades e recursos que articulam as aprendizagens na escola e no Museu Cargaleiro (Castelo Branco), na educação em ciências no 1º Ciclo do Ensino Básico (1º CEB). A investigação, com uma metodologia qualitativa, desenvolveu-se no âmbito do Estágio, numa turma de 4.ºano, inserindo-se na problemática da interação entre contextos de educação formal e não formal para a promoção da aprendizagem através da exploração de conexões das ciências com a arte. Para tal, planificámos uma visita de estudo ao Museu que contemplou a construção de recursos mediante o planeamento das três fases articuladas – antes, durante e após a visita. Da sequência didática, evidenciamos uma atividade de trabalho experimental que decorreu na fase após a visita, a fim de articular os conhecimentos adquiridos nas duas fases anteriores reforçando a compreensão dos fenómenos da luz e da cor, através da arte, envolvendo conhecimento da realidade próxima. Os resultados evidenciam que a aprendizagem dos alunos a nível de atitudes e capacidades e a nível cognitivo, avaliadas através de múltiplos registos, foi muito positiva.

Desenvolvimento e crescimento da espécie de cogumelo Pleurotus ostreatus em garrafas de plástico reutilizado

Dissertação de Mestrado, Tecnologia e Segurança Alimentar, 22 de Junho de 2016, Universidade dos Açores.

From the field to the table: ionizing radiation as a feasible postharvest treatment for fresh and dried plant foods

Food irradiation is a treatment that involves subjecting in-bulk or packaged food to a controlled dose of ionizing radiation, with a clearly defined goal. It has been used for disinfestation and sanitization of food commodities and to retard postharvest ripening and senescence processes, being a sustainable alternative to chemical agents 1 . Doses up to 10 kGy are approved by several international authorities for not offering negative effects to food from a nutrition and toxicology point of view 2 . However, the adoption of this technology for food applications has been a slow process due to some misunderstandings by the consumer who often chooses non-irradiated foods. In this study, the effects of the ionizing radiation treatment on physical, chemical and bioactive properties of dried herbs and its suitability for preserving quality attributes of fresh vegetables during cold storage were evaluated. The studied herbs, perennial spotted rockrose (Tuberaria lignosa (Sweet) Samp.) and common mallow (Malva neglecta Wallr.) were freeze-dried and then irradiated up to 10 kGy in a Cobalt-60 chamber. The selected vegetables, watercress (Nasturtium officinale R. Br.) and buckler sorrel (Rumex induratus Boiss. Reut.) were rinsed in tap water, packaged in polyethylene bags, submitted to irradiation doses up to 6 kGy and then were stored at 4 C for a period of up to 12 days. Physical, chemical and bioactive parameters of irradiated and non-irradiated samples were evaluated using different methodologies the colour was measured with a colorimeter, individual chemical compounds were analyzed by chromatographic techniques, antioxidant properties were evaluated using in vitro assays based on different reaction mechanisms, and other quality analyses were performed following official methods of analysis. The irradiation treatment did not significantly affect the colour of the perennial spotted rockrose samples, or its phenolic composition and antioxidant activity 3 . Medium doses preserved the colour of common mallow and a low dose did not induce any adverse effect in the organic acids profile. The green colour of the irradiated vegetables was maintained during cold storage but the treatment had pros and cons in other quality attributes. The 2 kGy dose preserved free sugars and favoured polyunsaturated fatty acids (PUFA) while the 5 kGy dose favoured tocopherols and preserved the antioxidant properties in watercress samples. The 6 kGy dose was a suitable option for preserving PUFA and the ω-6 ω-3 fatty acids ratio in buckler sorrel samples. This comprehensive experimental work allowed selecting appropriate processing doses for the studied plant foods in order to preserve its quality attributes and edibility.

Validação numérica de leis coesivas triangulares para previsão de resistência de juntas adesivas em tração e corte puros

As ligações adesivas surgiram pela necessidade de se encontrar formas de unir componentes, por vezes de materiais distintos, através de técnicas mais vantajosas. Atualmente, qualquer estrutura deve ser resistente, robusta e leve, o que amplificou o interesse industrial e investigação nas ligações adesivas, principalmente na melhoria das propriedades de resistência e fratura de materiais. Desta forma, nos últimos anos, a utilização de juntas adesivas em aplicações industriais tem aumentando gradualmente, substituindo alguns métodos de ligação tradicionais, por apresentarem vantagens, tais como redução de concentração de tensões, reduzido peso e facilidade de processamento/fabrico. Em qualquer área da indústria, a aplicação em larga escala de uma determinada técnica de ligação supõe que estão disponíveis ferramentas confiáveis para o projeto e previsão da rotura. Neste âmbito, os Modelos de Dano Coesivo (MDC) são uma ferramenta fundamental, apesar de ser necessário estimar as leis coesivas do adesivo à tração e corte para entrada nos modelos numéricos. Nesta dissertação o trabalho experimental consistiu no tratamento de dados com vista à obtenção de GIc e GIIc, com a devida comparação de diferentes métodos de redução, bem como potencialidades e limitações dos mesmos. É realizada uma comparação dos três adesivos: Araldite® AV138, Araldite® 2015 e SikaForce® 7752. Neste trabalho estudou-se também numericamente a adequação de leis coesivas triangulares na previsão no comportamento de juntas adesivas, nomeadamente nas curvas forçadeslocamento (P-) de ensaios Double-Cantilever Beam para caracterização à tração e ensaios End-Notched Flexure para caraterização ao corte. Os ensaios foram simulados numericamente pelo software ABAQUS®, recorrendo ao Método de Elementos Finitos (MEF) e um MDC triangular, com o intuito de estimar a lei coesiva de cada um dos adesivos. Para os adesivos Araldite®AV138 e Araldite®2015, à tração e ao corte, a lei triangular previu o comportamento do adesivo com alguma razoabilidade. Para a previsão da resistência do adesivo SikaForce® 7752, a lei triangular não se ajustou convenientemente nem à tração nem ao corte. Considera-se que, para este adesivo, uma lei trapezoidal é a que melhor se adequa, devido à ductilidade do mesmo.

Comportamento de Staphylococcus sob diferentes condições de crescimento: Behaviour of Staphylococcus aureus under different growth conditions

Realizou-se um trabalho experimental com o objectivo de obter informação sobre a evolução do crescimento de Staphylococcus aureus. Foram utilizadas duas estirpes de Staphylococcus aureus, uma isolada a partir de rissóis de frango e uma estirpe de referência, a ATCC n. 9213, estas estirpes foram sujeitas a 3 valores de pH diferentes (que representam os valores de pH que é possível, ou seja pH 4, 5,5 e 7, a 3 valores de concentração de NaCl, nomeadamente, 0,5%, 7% e 15%. A temperatura de desenvolvimento será de 7°C, 37°C e 50aC. Utilizaram-se dois métodos para avaliar o crescimento de Staphylococcus aureus, ao longo do tempo, nomeadamente o Método Turbidímétrico e o Método de contagem de unidades formadoras de colónias (método das diluições sucessivas). ABSTRACT: Carried out experimental work in order to obtain information on the evolution of the growth of Staphylococcus aureus. We used two strains of Staphylococcus aureus, a strain isolated from a chicken patties and one reference strain, ATCC Nº 29213, these strains were subjected to 3 different pH values (which represent the values of pH it is possible, or is pH 4, 5.5 and 7, the 3 values of NaCI concentration, namely, 0.5%, 7% and 15%. The growth temperature is 7 °C, 37°C and 50ºC. We used two methods to evaluate the growth of Staphylococcus aureus, over time, including the turbidimetric method and the method of counting colony forming units (method of successive dilutions).

Cottage cheeses functionalized with fennel and chamomile extracts: comparative performance between free and microencapsulated forms

Globally, there is a trend for healthy food products, preferably incorporating natural bioactive ingredients, replacing synthetic additives. From previous screening studies, extracts of Foeniculum vulgare Mill. (fennel) and Matricaria recutita L. (chamomile) maintained nutritional properties and improved the antioxidant activity of cottage cheese. Nevertheless, this effect was limited to 7 days. Accordingly, aqueous extracts of these plants were microencapsulated in alginate and incorporated into cottage cheese to achieve an extended bioactivity. Plain cottage cheese, and cheese functionalized by direct addition of free decoctions, were prepared and compared. Independently of plant species, "functionalization type" factor did not show a significant effect on the nutritional parameters, as also confirmed in the linear discriminant analysis, where these parameters were not selected as discriminating variables. Furthermore, samples functionalized with microencapsulated extracts showed higher antioxidant activity after the 7th day, thereby demonstrating that the main purpose of this experimental work was achieved.

The effect of chaperone compounds on glucocerebrosidase stability and activity in fibroblasts from Gaucher Disease patients with different genotypes

Dissertação de mestrado, Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 2014

Avaliação do efeito de particulados sólidos na eficiência de um inibidor de corrosão recomendado para meios salinos com CO2

The main problem on the exploration activity on petroleum industry is the formation water resulted on the fields producing. The aggravating of this problem is correlated with the advancing technologies used on the petroleum extractions and on its secondary approach objecting the reobtainment of this oil. Among the main contaminants of the water formation are corrosives gases such as: O2, CO2 and H2S, some solids in suspension and dissolved salts. Concerning to those gases the CO2 is the one that produce significant damage for carbon steel on corrosion process of the petroleum and gas industries. Corrosion inhibitors for carbon steel in formation water is one of the most used agents in control of those damages. In this context, the poor investigations of carbon steel corrosion proceeding from solids in suspension is an opened field for studies. On this work the inhibitor effect of the commercial CORRTREAT 703 was evaluated on some specific solids in suspension at saline medium containing 10.000 ppm of de-aerated chloride using CO2 until non oxygen atmosphere been present. For that, quartz, calcium carbonate, magnetite and iron sulphide were subjected to this investigation as the selected solids. The effect of this inhibitor on corrosion process correlated with those specific solids, was measured using electrochemical (resistance of linear polarization and galvanic pair) and gravimetrical techniques. During all the experimental work important parameters were monitored such as: pH, dissolved oxygen, temperature, instantaneous corrosion rate and galvanic current. According to the obtained results it was proved that the suspension solids calcium carbonate and iron sulphide decrease the corrosion process in higher pH medium. Meanwhile the quartz and magnetite been hardness increase corrosion by broking of the passive layer for erosion. In the other hand, the tested inhibitor in concentration of 50 ppm, showed to be effective (91%) in this corrosion process

Ab Initio Quantum Chemical Studies on Neutral-Radical Reactions of Ethynyl (C2H) and Cyano (CN) with Unsaturated Hydrocarbons

An Ab Initio/RRKM study of the reaction mechanism and product branching ratios of neutral-radical ethynyl (C2H) and cyano (CN) radical species with unsaturated hydrocarbons is performed. The reactions studied apply to cold conditions such as planetary atmospheres including Titan, the Interstellar Medium (ISM), icy bodies and molecular clouds. The reactions of C2H and CN additions to gaseous unsaturated hydrocarbons are an active area of study. NASA’s Cassini/Huygens mission found a high concentration of C2H and CN from photolysis of ethyne (C2H2) and hydrogen cyanide (HCN), respectively, in the organic haze layers of the atmosphere of Titan. The reactions involved in the atmospheric chemistry of Titan lead to a vast array of larger, more complex intermediates and products and may also serve as a chemical model of Earth’s primordial atmospheric conditions. The C2H and CN additions are rapid and exothermic, and often occur barrierlessly to various carbon sites of unsaturated hydrocarbons. The reaction mechanism is proposed on the basis of the resulting potential energy surface (PES) that includes all the possible intermediates and transition states that can occur, and all the products that lie on the surface. The B3LYP/6-311g(d,p) level of theory is employed to determine optimized electronic structures, moments of inertia, vibrational frequencies, and zero-point energy. They are followed by single point higher-level CCSD(T)/cc-vtz calculations, including extrapolations to complete basis sets (CBS) of the reactants and products. A microcanonical RRKM study predicts single-collision (zero-pressure limit) rate constants of all reaction paths on the potential energy surface, which is then used to compute the branching ratios of the products that result. These theoretical calculations are conducted either jointly or in parallel to experimental work to elucidate the chemical composition of Titan’s atmosphere, the ISM, and cold celestial bodies.

Effect of pH and temperature on the carbonate promoted dissolution of sodium meta-autunite

Release of uranium from Na-autunite, an artificial mineral created as a result of polyphosphate injection in the subsurface at the DOE Hanford Site, takes place during slow dissolution of the mineral structure. Stability information of the uranyl-phosphate phases is limited to conditions involving pH, temperature, and a few aqueous organic materials. The carbonate ion, which creates very strong complexes with uranium, is the predominant ion in the groundwater composition. The polyphosphate technology with the formation of autunite was identified as the most feasible remediation strategy to sequester uranium in contaminated groundwater and soil in situ. The objectives of the experimental work were (i) to quantify the effect of bicarbonate on the stability of synthetic sodium meta-autunite created as a result of uranium stabilization through polyphosphate injection, (ii) calculate the kinetic rate law parameters of the uranium release from Na-autunite during dissolution, and (iii) to compare the process parameters with those obtained for natural calcium meta-autunite. Experiments were conducted using SPTF apparatus, which consists of syringe pumps for controlling flow rate, Teflon reactors and a heating/cooling system. 0.25 grams of synthetic Na-autunite was placed in the reactor and buffer solutions with varying bicarbonate concentrations (0.0005 to 0.003 M) at different pH (6 - 11) were pumped through the reactors. Experiments were conducted at four different temperatures in the range of 5 - 60oC. It was concluded that the rate of release of uranium from synthetic Na-autunite is directly correlated to the bicarbonate concentration. The rate of release of uranium increased from 1.90 x 10-12 at pH 6 to 2.64 x 10-10 (mol m-2 s-1) at pH 11 at 23oC over the bicarbonate concentration range tested. The activation energy values were invariant with the change in the bicarbonate concentration; however, pH is shown to influence the activation energy values. Uranyl hydroxides and uranyl carbonates complexes helped accelerate the dissolution of autunite mineral.

A Model for Continuous Measurement of Drilled Shaft Diameter During Construction

Non-Destructive Testing (NDT) of deep foundations has become an integral part of the industry’s standard manufacturing processes. It is not unusual for the evaluation of the integrity of the concrete to include the measurement of ultrasonic wave speeds. Numerous methods have been proposed that use the propagation speed of ultrasonic waves to check the integrity of concrete for drilled shaft foundations. All such methods evaluate the integrity of the concrete inside the cage and between the access tubes. The integrity of the concrete outside the cage remains to be considered to determine the location of the border between the concrete and the soil in order to obtain the diameter of the drilled shaft. It is also economic to devise a methodology to obtain the diameter of the drilled shaft using the Cross-Hole Sonic Logging system (CSL). Performing such a methodology using the CSL and following the CSL tests is performed and used to check the integrity of the inside concrete, thus allowing the determination of the drilled shaft diameter without having to set up another NDT device. This proposed new method is based on the installation of galvanized tubes outside the shaft across from each inside tube, and performing the CSL test between the inside and outside tubes. From the performed experimental work a model is developed to evaluate the relationship between the thickness of concrete and the ultrasonic wave properties using signal processing. The experimental results show that there is a direct correlation between concrete thicknesses outside the cage and maximum amplitude of the received signal obtained from frequency domain data. This study demonstrates how this new method to measuring the diameter of drilled shafts during construction using a NDT method overcomes the limitations of currently-used methods. In the other part of study, a new method is proposed to visualize and quantify the extent and location of the defects. It is based on a color change in the frequency amplitude of the signal recorded by the receiver probe in the location of defects and it is called Frequency Tomography Analysis (FTA). Time-domain data is transferred to frequency-domain data of the signals propagated between tubes using Fast Fourier Transform (FFT). Then, distribution of the FTA will be evaluated. This method is employed after CSL has determined the high probability of an anomaly in a given area and is applied to improve location accuracy and to further characterize the feature. The technique has a very good resolution and clarifies the exact depth location of any void or defect through the length of the drilled shaft for the voids inside the cage. The last part of study also evaluates the effect of voids inside and outside the reinforcement cage and corrosion in the longitudinal bars on the strength and axial load capacity of drilled shafts. The objective is to quantify the extent of loss in axial strength and stiffness of drilled shafts due to presence of different types of symmetric voids and corrosion throughout their lengths.

Different Parameters Variation Analysis of a PV Cell

The paper states an introduction, description and implementation of a PV cell under the variation of parameters. Analysis and observation of a different parameters variation of a PV cell are discussed here. To obtain the model for the purpose of analyzing an equivalent circuit with the consisting parameters a photo current source, a series resistor, a shunt resistor and a diode is used. The fundamental equation of PV cell is used to study the model and to analyze and best fit observation data. The model can be used in measuring and understanding the behaviour of photovoltaic cells for certain changes in PV cell parameters. A numerical method is used to analyze the parameters sensitivity of the model to achieve the expected result and to understand the deviation of changes in different parameters situation at various conditions respectively. The ideal parameters are used to study the models behaviour. It is also compared the behaviour of current-voltage and power-voltage by comparing with produced maximum power point though it is a challenge to optimize the output with real time simulation. The whole working process is also discussed and an experimental work is also done to get the closure and insight about the produced model and to decide upon the validity of the discussed model.

Investigation of innovative combustion systems for reduced fuel consumption and increased specific power production

This work resumes a wide variety of research activities carried out with the main objective of increasing the efficiency and reducing the fuel consumption of Gasoline Direct Injection engines, especially under high loads. For this purpose, two main innovative technologies have been studied, Water Injection and Low-Pressure Exhaust Gas Recirculation, which help to reduce the temperature of the gases inside the combustion chamber and thus mitigate knock, being this one of the main limiting factors for the efficiency of modern downsized engines that operate at high specific power. A prototypal Port Water Injection system was developed and extensive experimental work has been carried out, initially to identify the benefits and limitations of this technology. This led to the subsequent development and testing of a combustion controller, which has been implemented on a Rapid Control Prototyping environment, capable of managing water injection to achieve knock mitigation and a more efficient combustion phase. Regarding Low-Pressure Exhaust Gas Recirculation, a commercial engine that was already equipped with this technology was used to carry out experimental work in a similar fashion to that of water injection. Another prototypal water injection system has been mounted to this second engine, to be able to test both technologies, at first separately to compare them on equal conditions, and secondly together in the search of a possible synergy. Additionally, based on experimental data from several engines that have been tested during this study, including both GDI and GCI engines, a real-time model (or virtual sensor) for the estimation of the maximum in-cylinder pressure has been developed and validated. This parameter is of vital importance to determine the speed at which damage occurs on the engine components, and therefore to extract the maximum performance without inducing permanent damages.

Percutaneous Cement Discoplasty: Biomechanical and clinical assessment of a minimally invasive treatment of lumbar intervertebral disc disease

With population ageing, spine diseases have an increasing prevalence and induce high economic and social costs. The development of minimally invasive surgeries allows reducing the surgery-associated risks in elderly and polymorbid patients, and save costs by treating more patients in shorter time and reducing the complications. Percutaneous Cement Discoplasty (PCD) is a minimally invasive technique developed to treat highly degenerated intervertebral discs exhibiting a vacuum phenomenon. Filling the disc with bone cement creates a stand-alone spacer which partially restores the disc height and re-opens the foraminal space. PCD has recently been introduced to clinical use. However, the spine biomechanics following this treatment remained unravelled. The aim of this PhD thesis is to bridge the clinical experience with in vitro methodologies, to provide a multilateral evaluation of PCD outcome and a better understanding of its impact on the spine biomechanics, and of its possible contraindications. Firstly, a suitable in vitro porcine model to test the biomechanics of discoplasty by comparing specimens in the preoperative and postoperative conditions was developed. The methodology was then applied to investigate the biomechanics of discoplasty in cadaveric human segments. The in vitro specimens were mechanically investigated in flexion and extension, while a DIC system quantified the range of motion, disc height, and strains on the disc surface. Then, a versatile tool to measure the impact of discoplasty on the foramen space was developed and applied both to clinical and experimental work. The vertebrae reconstructed from CT scans were registered to match the loading configuration, using ex vivo DIC measurements under loading. The foramen volumetric changes caused by PCD was measured using a 3D geometrical method clinically developed by the research group. In conclusion, this project significantly extended the understanding of PCD biomechanics, highlighting its benefits in the treatment of advanced cases of intervertebral disc degeneration.