36,302 research outputs found

    Estudo dos efeitos da incorporação de TPE reciclado em PC-ABS reciclado

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    Disserta√ß√£o de mestrado integrado em Engenharia de Pol√≠merosO prop√≥sito deste projeto √© a avalia√ß√£o da possibilidade de reciclagem de componentes oriundos da molda√ß√£o por inje√ß√£o multimaterial, constitu√≠dos por misturas de PC/ABS e TPS e misturas de PC/ABS e TPU. Esta t√©cnica de inje√ß√£o apresenta vantagens t√©cnicas e econ√≥micas, no entanto contribui para o desperd√≠cio de mat√©ria prima, nomeadamente em forma de pe√ßas n√£o conformes e do sistema de alimenta√ß√£o. Este estudo tem como objetivo contribuir para a circularidade dos materiais, avaliando a possibilidade de aproveitamento destes desperd√≠cios. Para isso estudaram-se os materiais individualmente e em misturas preparadas numa gama de concentra√ß√Ķes dos componentes, simulando-se o aproveitamento dos desperd√≠cios do processo de inje√ß√£o multimaterial. As misturas foram produzidas por extrus√£o de duplo fuso e as amostras para carateriza√ß√£o foram produzidas por molda√ß√£o por inje√ß√£o. O aumento de TPE na mistura originou uma redu√ß√£o de propriedades mec√Ęnicas, nomeadamente a ductilidade e o impacto. O √≠ndice fluidez das misturas de materiais aumenta com o aumento da fra√ß√£o de TPE, o que est√° relacionado com o √≠ndice de fluidez elevado dos TPE, mas tamb√©m com a degrada√ß√£o termomec√Ęnica sofrida pelos materiais. Assim, verificou-se que a incorpora√ß√£o de TPE deve ser controlada de modo a n√£o reduzir significativamente as propriedades das pe√ßas relativamente √†s de PC/ABS. Para investigar a possibilidade da integra√ß√£o de reciclado bimaterial foi tamb√©m testada a pintura UV. Este processo √© utilizado para todos os componentes produzidos, por isso a incorpora√ß√£o de misturas de materiais, assim como de reciclado, deve admitir o processo de pintura. Concluiu-se que as pe√ßas produzidas com reciclado e TPE passaram a avalia√ß√£o do processo de pintura. Considerando a grande quantidade de desperd√≠cio produzido no processo de inje√ß√£o em canais de alimenta√ß√£o de TPE, caraterizaram-se tamb√©m as propriedades mec√Ęnicas dos TPE reprocessados. Conclui-se que estes materiais n√£o perdem caracter√≠sticas mec√Ęnicas ap√≥s 1 ciclo de reprocessamento, mostrando o seu potencial para reciclagem. Por √ļltimo, sendo o TPE sobremoldado no PC/ABS, foi tamb√©m avaliada a ades√£o dos dois TPE (TPS e TPU) ao PC/ABS, tendo-se verificado que o TPU apresenta melhores propriedades de ades√£o ao PC/ABS em compara√ß√£o com o TPS.The purpose of this project is to evaluate the possibility of recycling components from multi-material injection molding, consisting of mixtures of PC/ABS and TPS and mixtures of PC/ABS and TPU. This injection technique has technical and economic advantages, however, it contributes to the waste of raw material, namely in the form of non-conforming parts and the feeding system. This study aims to contribute to the circularity of materials, evaluating the possibility of using these wastes. For this, the materials were studied individually and in mixtures prepared in a range of concentrations of the components, simulating the use of waste from the multi-material injection process. The mixtures were produced by extrusion technique with a twin screw and the samples for characterization were produced by injection molding. Rheological, mechanical and surface characteristics of the mixtures of parts made up of virgin PC/ABS were evaluated for comparison. The increase in TPE in the mixture resulted in a reduction of mechanical properties of the bicomponent material, namely ductility and impact. The melt flow index of the mixed materials increases with the increase in the TPE content, which is related to the high melt flow index of TPE, and possibly due the thermomechanical degradation suffered by the materials. Thus, it was found that the incorporation of TPE must be controlled so as not to significantly reduce the properties of the parts compared to those of PC/ABS. To investigate the possibility of integrating bimaterial recycled in the same process, UV paint was also tested. This process is used for all components produced, so the incorporation of mixtures of materials, as well as recycled, must admit the painting process. It was concluded that the pieces produced with recycled and TPE passed the evaluation of the painting process. Considering the large amount of waste produced in the injection process in TPE feeding channels, the mechanical properties of the reprocessed TPE were also characterized. It is concluded that these materials do not lose mechanical characteristics after 1 reprocessing cycle, showing their potential for recycling. Finally, since the TPE is overmolded in the PC/ABS, the adhesion of the two TPE (TPS and TPU) to the PC/ABS was evaluated, and it was found that the TPU has better adhesion properties to the PC/ABS compared to the TPS

    Revisão taxonómica do género Calendula L. (Asteraceae - Calenduleae) na Península Ibérica e Marrocos

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    The genus Calendula L. (Asteraceae - Calenduleae) includes, depending on the author, 10 to 25 species, distributed mainly in the Mediterranean basin. The taxonomy of this genus is considered to be extremely difficult, due to a great morphological variability, doubtfull relevance of some of the characters used to distinguish its species (e.g. the life form: annual or perennial; the habit: erect or diffuse, shape of the leaves, indumentum, relative size of the capitula and colour of disc or ray florets, achene morphology), but also due to the hybridization and polyploidization. Despite the numerous studies that have been published, no agreement on the classification and characters used to discriminate between taxa has been reached. A taxonomic study of the genus Calendula was conducted for the Iberian Peninsula and Morocco, aiming at (1) access the morphological variability between and within taxa, (2) confirm the chromosome numbers, (3) increase the nuclear DNA content estimations, (4) re-evaluate taxa delimitations and circumscription, and (5) reassess, and redefine, the descriptions and characters useful to distinguish taxa. In order to achieve a satisfying taxonomic core, extensive fieldwork, detailed morphometric analysis, chorological, karyological and genome size studies were conducted. For the Iberian Peninsula, four species were recognized, including nine subspecies (between these two new subspecies were described). For Morocco, including some taxa from Algeria and Tunisia 13 species were recognized (two new species and a nomenclatural change), including 15 subspecies (among these eight new subspecies were described). To corroborate the results obtained and to evaluate the evolutionary relationships among taxa, phylogenetic studies using molecular methods, such as ITS, microsatellites or other molecular markers, should be used.O g√©nero Calendula L. (Asteraceae - Calenduleae) inclui, dependendo do autor, 10 a 25 esp√©cies, distribu√≠das essencialmente na bacia do Mediterr√Ęneo. A taxonomia deste g√©nero √© considerada extremamente dif√≠cil, devido √† grande variabilidade morfol√≥gica, discutivel relev√Ęncia de alguns dos caracteres utilizados para distinguir suas esp√©cies (por exemplo, a forma de vida: anual ou perene, o h√°bito: erecto ou difuso, a forma das folhas, o indumento, o tamanho e a cor dos cap√≠tulos e a morfologia dos aqu√©nios), mas tamb√©m devido √† hibridiza√ß√£o e poliploidiza√ß√£o. Apesar dos in√ļmeros estudos que foram publicados, n√£o foi alcan√ßado um acordo sobre a classifica√ß√£o e os caracteres utilizados para discriminar as suas esp√©cies. Um estudo taxon√≥mico do g√©nero Calendula foi realizado para a Pen√≠nsula Ib√©rica e Marrocos, com o objectivo de (1) verificar a variabilidade morfol√≥gica, (2) confirmar o n√ļmero de cromossomas, (3) aumentar as estimativas de conte√ļdo em ADN, (4) reavaliar a delimita√ß√£o e a circunscri√ß√£o dos taxa, e (5) reavaliar e redefinir as descri√ß√Ķes e caracteres √ļteis para os distinguir. Para alcan√ßar uma robust√™s taxon√≥mica satisfat√≥ria, foram realizados extensos trabalhos de campo, an√°lise morfom√©trica detalhada, abordagens corol√≥gicas, cariol√≥gicas e quanto ao conte√ļdo em ADN. Para a Pen√≠nsula Ib√©rica, quatro esp√©cies foram reconhecidas, incluindo nove subesp√©cies (entre essas duas novas subesp√©cies foram descritas). Para Marrocos, incluindo alguns taxa da Argelia e Tunisia, foram reconhecidas 13 esp√©cies (duas novas e uma mudan√ßa nomenclatural), incluindo 15 subesp√©cies (entre essas oito novas subesp√©cies foram descritas). Para corroborar os resultados obtidos e avaliar as rela√ß√Ķes evolutivas e filogen√©ticas entre os taxa, estudos que utilizem diferentes m√©todos moleculares, tais como ITS, microsat√©lites ou outros marcadores moleculares, devem ser utilizados.Apoio financeiro do Laborat√≥rio Associado CESAM - Centro de Estudos do Ambiente e do Mar (AMB/50017) financiado por fundos nacionais atrav√©s da FCT/MCTES e cofinanciado pelo FEDER (POCI-01-0145-FEDER-007638), no √Ęmbito do Acordo de Parceria PT2020, e Compete 2020Programa Doutoral em Biologi

    Manufacture of rich-sulfoaluminate belite cement at low temperature from waste mixture by dry and hydrothermal processes

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    This study, within the framework of eco-cement development, aims to manufacture reactive belite-sulfoaluminate cement (BYF) as alternative to Portland cement (PC). This ecological cement is obtained at low temperature from a mixture of industrial wastes using two synthetic methods, dry and hydrothermal treatment. The main minerals of this cement are ő≤-C2S and calcium sulfoaluminate (C4A3҆), the latter being very reactive, which provide high performances cementitious materials. The hydrothermal treatment of raw mixture led to reduce the burning temperature of clinker up to 1200 ¬įC. The mineral phases of the produced cements and theirs pastes were identified and quantified by XRPD coupled with Rietveld method. The hydraulic reactivity of cement was studied using XRPD and thermal analyses. The resulting mortars are very reactive and develop more than 42 MPa of compressive strengths after 28 days.UMA18-FEDERJA-095 y P18-RT-720 (ambos cofinanciados FEDER

    Aplicação de conceitos Lean no planeamento e compra de produtos químicos numa empresa de lentes oftálmicas

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    Disserta√ß√£o de mestrado em Engenharia IndustrialA presente tese de mestrado foi desenvolvida na empresa Amazon Vision, em Manaus, com o principal objetivo melhorar a gest√£o de planeamento e compra de produtos qu√≠micos, mediante a aplica√ß√£o de conceitos Lean. Buscou-se reduzir os erros de processo; reduzir as atividades que n√£o agregavam valor √† cadeia, al√©m de reduzir custos. Na disserta√ß√£o foi utilizada a metodologia Investiga√ß√£o-A√ß√£o que contempla cinco fases: diagn√≥stico, planeamento, a√ß√£o, avalia√ß√£o e especifica√ß√£o da aprendizagem. Come√ßou-se pela an√°lise da situa√ß√£o atual utilizando a ferramenta 5 Whys, onde foram identificados os principais problemas a seguir: falta de gerenciamento dos produtos em decl√≠nio; falta de comunica√ß√£o sobre as altera√ß√Ķes dos Master Plan; falta de defini√ß√£o de uma pol√≠tica macro de estoque de seguran√ßa e a falta de uma efetiva gest√£o de controlo de scrap de material. Ap√≥s a identifica√ß√£o dos problemas e desperd√≠cios, e com a utiliza√ß√£o da ferramenta 5W2H, foram definidas as seguintes propostas de melhorias: cria√ß√£o de rotina de acompanhamento (Phase-in e Phase-out) dos produtos; implementa√ß√£o de um procedimento de an√°lise de materiais para as altera√ß√Ķes de demandas no Master Plan; implementa√ß√£o de uma pol√≠tica de estoque de seguran√ßa para produtos planeados atrav√©s de m√≠nimo e m√°ximo e a cria√ß√£o de um procedimento para an√°lise das causas raiz de scrap de materiais. Com essas propostas foram alcan√ßados os seguintes resultados: redu√ß√£o de R398.952,16emdesperdńĪňäciosrelacionadosaolanc\camentoedeclńĪňäniodeprodutos,aleňämdamelhoriadacomunicac\ca~oentreasequipasdeNovosProdutoseCompraseatualizac\ca~odainstruc\ca~odetrabalho;reduc\ca~odeR 398.952,16 em desperd√≠cios relacionados ao lan√ßamento e decl√≠nio de produtos, al√©m da melhoria da comunica√ß√£o entre as equipas de Novos Produtos e Compras e atualiza√ß√£o da instru√ß√£o de trabalho; redu√ß√£o de R 170.776,90 em desperd√≠cios ligados a atualiza√ß√£o de demandas do Master Plan, melhoria da comunica√ß√£o entre Compras e o Planeamento e Controlo de Produ√ß√£o - PCP atrav√©s da realiza√ß√£o de reuni√Ķes e atualiza√ß√£o da instru√ß√£o de trabalho; redu√ß√£o de R22.119,90emdesperdńĪňäciosrelacionadosaňčpolńĪňäticadeestoquedeseguranc\cademateriais,definic\ca~odeumapolńĪňäticamacrodeestoquedeseguranc\caereduc\ca~ode62 22.119,90 em desperd√≠cios relacionados √† pol√≠tica de estoque de seguran√ßa de materiais, defini√ß√£o de uma pol√≠tica macro de estoque de seguran√ßa e redu√ß√£o de 62% no n√ļmero de itens cr√≠ticos para a produ√ß√£o. O total de poupan√ßa com as medidas implementadas foi R 591.848,96, equivalente a cerca de ‚ā¨ 89.000,00 entre Janeiro a Agosto de 2021.This master‚Äôs thesis has been developed at the company Amazon Vision, with the main objective of improving the management of planning and purchases chemical products, thorough the application of Lean concepts. It also pursued to reduce process mistakes; to reduce activities that did not add value to chain, in addition to reducing costs. It was used the methodology Action Research, which has five phases: diagnosing, action planning, taking action, evaluating and specifying learning. It started by analyzing the current situation using the 5 Whys tool, where the following problems have been found: lack of management of declining products; lack of communication about Master Plan changes; lack of definition of a macro safety stock policy and the lack of an effective management of material scrap control. After the identification of problems and wastes, and using the 5W2H tool, the following improvement proposals have been defined: creation of routine monitoring (Phase-in and Phase-out) of the products; implementation of a materials analysis procedure for changing demands in Master Plan; implementation of a safety stock policy for products planned through minimum and maximum, and also the creation of a procedure for analyzing the root causes of scrap material. With those proposals the following results have been achieved: reduction of R398.952,16inwastesrelatedtothelaunchanddeclineofproducts,besidesthecommunicationimprovementbetweenNewProductsandPurchasingTeamsandupdateofStandardWork;reductionofR 398.952,16 in wastes related to the launch and decline of products, besides the communication improvement between New Products and Purchasing Teams and update of Standard Work; reduction of R 170.776,90 in wastes related to updating Master Plan demands and communication improvement between Production and Control Planning ‚Äď PCP and Purchasing teams, and update of Standard Work, and the reduction of R22.119,90inwastesrelatedtothesafetystockpolicyandreductionof62 22.119,90 in wastes related to the safety stock policy and reduction of 62% in the number of critical item for production. The total savings with the implemented measures was R 591.848,96, equivalent to around ‚ā¨ 89.000,0 between January and August 2021

    Mechanical and durability properties of concrete incorporating glass and plastic waste

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    The main objective of this work is to contribute to the valorization of plastic and glass waste in the improvement of concrete properties. Waste glass after grinding was used as a partial replacement of the cement with a percentage of 15%. The plastic waste was cut and introduced as fibers with 1% by the total volume of the mixture. Mechanical and durability tests were conducted for various mixtures of concrete as compressive and flexural strengths, water absorption, ultrasonic pulse velocity, and acid attack. Also, other in-depth analyses were performed on samples of each variant such as X-ray diffraction (XRD), thermogravimetric analysis (DSC-TGA), and scanning electron microscope (SEM). The results show that the addition of glass powder or plastic fibers or a combination of both in concrete improved in the compression and flexural strengths in the long term. The highest compressive strength was obtained in the mix which combines the two wastes about 26.72% of increase compared to the control concrete. The flexural strength increased in the mixture containing the glass powder. Therefore, the mixture with two wastes exhibits better resistance to aggressive sulfuric acid attack, and incorporating glass powder improves the ultrasonic pulse velocity

    Water treatment sludge as precursor in non-dehydroxylated kaolin-based alkali-activated cements

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    Cement industry production and its materials demand are growing every year, leading to a CO2 and energy footprint increase. The drinking water production is increasing in water treatment plants due to the population growth, raising in turn the waste materials produced. Since these wastes are mainly managed in landfills, this preliminary research work is focused on providing a new sustainable option for valorisation processes, based on the environmental demand of the cement industry. Alkali-activated cements (AACs) can become a proper option to give the water treatment sludge a new life cycle, as they can compete with ordinary Portland cement (OPC) both in properties and sustainability. The main purpose of this study was to evaluate and formulate different AACs based on the use of both raw clay and the water treatment sludge (WTS), as precursors. The raw clay was used without previous thermal dehydroxylation treatment, and the WTS, an aluminosilicate-rich waste, was used partially replacing the raw clay in the AACs formulations. Both precursors and the formulated AACs were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Fourier-transformed infrared spectroscopy (FT-IR). In addition, the compressive strength, the chemical stability (hydrolytic degradation), and the environmental impact for each AACs formulation were also determined. The results showed that AACs specimens formulated with 20 wt% of WTS (replacing the raw clay) provided the best results, considering both compressive strength and resistance to hydrolytic degradation. Then, it is possible to formulate AACs using raw clay, without prior thermal dehydroxylation treatment, and WTS as precursors

    Contributions to environmental management in a metalworking industry

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    Disserta√ß√£o de mestrado em Gest√£o AmbientalPor amar a natureza e por me amar a mim e aos meus, acredito que vale a pena fazer alguma coisa por n√≥s. A economia comanda o mundo e o que a movimenta s√£o as empresas que produzem o que as pessoas compram e √© esta a realidade que faz girar o mundo. Por norma as empresas tinham de contribuir com bons produtos ou bons servi√ßos, para os clientes, para que eles lhes entregassem o seu dinheiro voluntariamente, de modo fiel e cont√≠nuo. A necessidade de uma empresa ser competitiva √© constante, devido √†s exig√™ncias da economia envolvente, que n√£o se compadece com uma qualidade que n√£o gere lucros. No entanto, esta realidade tem vindo a alterar-se, pois a sociedade rejeita uma empresa que produza artigos ou servi√ßos nocivos ou destrutivos. As empresas agora s√£o marcas que t√™m personas claramente identific√°veis e, quando s√£o publicamente criticadas, sofrem perdas consider√°veis em termos de reputa√ß√£o o que se reflete diretamente nos pre√ßos das suas a√ß√Ķes. Se uma empresa prejudicar a sa√ļde humana ou o meio ambiente, o seu valor de mercado √© afetado e √© penalizada por adotar uma conduta reprov√°vel. A prioridade √© produzir melhor, em detrimento do produzir mais. O desenvolvimento do presente projeto na empresa metalomec√Ęnica pretendeu estudar os contributos que uma boa gest√£o ambiental pode trazer, quer a uma melhor efici√™ncia ambiental, quer a uma melhor produ√ß√£o. Para tal, procedeu-se a uma breve descri√ß√£o do seu funcionamento. Seguiu-se a abordagem das etapas dos processos produtivos, procedendo-se √† elabora√ß√£o de instru√ß√Ķes de trabalho, com vista ao desenvolvimento de uma pol√≠tica de gest√£o integrada ambiente/qualidade, enquadrada nas conformidades legais. Elaborou-se uma matriz de impactos e riscos, classificaram-se os res√≠duos segundo o c√≥digo LER e a sua perigosidade e estabeleceram-se regras para a sua correta recolha e armazenamento, valorizaram-se os res√≠duos, como √≥leos e √°guas das lamas. Todas estas medidas foram a base para a proje√ß√£o do novo parque de res√≠duos para a nova unidade fabril. Paralelamente analisou-se a possibilidade da substitui√ß√£o de produtos/equipamentos por outros similares mas mais sustent√°veis com vista a reduzir a sua pegada ecol√≥gica. Embora o projeto tenha alcan√ßado os objetivos pretendidos, a empresa deve procurar melhorar o seu desempenho de modo a continuar competitiva, apostando na inova√ß√£o e revis√£o dos seus processos, mas sem que o ambiente sinta a sua presen√ßa! Concluo com uma cita√ß√£o de John Milton, que dispensa explica√ß√Ķes, mas que nos obriga a pensar na parte que nos cabe: ‚ÄúN√£o acuse a natureza, ela faz a parte que lhe cabia. Agora, fa√ßa a sua.‚ÄĚBecause I love nature and I love me and my own, I believe it is worth doing something for us. The economy rules the world, and what drives it are the companies that produce what people buy and this is the reality that makes the world go round. As a rule, companies had to contribute with good products or good services to their customers so that they would give them their money voluntarily, faithfully and continuously. The need for a company to be competitive is constant, due to the demands of the surrounding economy, which does not sympathize with a quality that does not generate profit. However, this reality is changing as society rejects a company that produces harmful or destructive articles or services. Companies are now brands that have clearly identifiable personas and, when publicly criticized, suffer considerable reputational losses, which are reflected directly in their stock prices. If a company harms human health or the environment, its market value is affected and it is penalized for engaging in reprehensible conduct. The priority is to produce better, over produce more. The development of this project in the metalworking company intended to study the contributions that good environmental management can bring, both to a better environmental efficiency and to a better production. To this end, a brief description of its operation was given. This was followed by the approach of the stages of the productive processes, proceeding to the elaboration of work instructions, with a view to the development of an integrated management policy environment/quality, framed in the legal conformity. A matrix of impacts and risks was elaborated, the wastes were classified according to the LER code and its hazard and rules were established for its correct collection and storage. All these measures were the basis for the projection of the new wastes park for the new factory. At the same time, the possibility of replacing products/equipments with similar but more sustainable ones in order to reduce their ecological footprint were examined. Although the project has achieved its intended objectives, the company must strive to improve its performance in order to remain competitive, betting on innovation and review of its processes, but without the environment feeling its presence! I conclude with a quote by John Milton, which needs no explanation, but forces us to think about our part: ‚ÄúDon't accuse nature, it does its part. Now, make yours.

    H. portulacoides and J. maritimus em sapal contaminado por merc√ļrio: acumula√ß√£o de metal, padr√Ķes bioqu√≠micos e lipid√≥micos

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    Mestrado em Biologia Molecular e CelularThe salt marshes, one of the most productive ecosystems, serves as the sink for contaminants, namely metals from industries, reducing in this way the contamination of surrounding ecosystems. Although, as levels of contaminants, the ability of salt marshes to incorporate wastes can be impaired. In the aquatic environment, high mercury (Hg) pollution is mainly due to metal discharge of effluents from chloralki plants containing high concentrations of this metal. Mercury has been recognized as heavy metal and extremely toxic to plants interfering with several crucial cellular processes. This study evidenced the importance to understand the analysis that plants under environmental exposed to Hg and to evaluate impact of Hg toxicity in plants salt marsh communities. Better knowledge on these accumulation aspects will evaluate the stress imposed by Hg on primary production in salt marsh plants and adaptation of mobility of the metal in the ecosystem. As well as the molecular mechanisms mercury tolerance, which are important to clean efficiently Hg contaminated systems in order to an effective restoration is achieved. In this way, the work focused on two species of halophytes, Halimione portulacoides and Juncus maritimus collected at two sites of the Ria de Aveiro contaminated by mercury, considered s1 as less contaminated site and s2 as the most contaminated site. Thus, this work was designed to (1) evaluate how Hg distribution in plants would avoid high Hg concentrations (2) which way plants would retain Hg toxicity by triggering antioxidant responses. Indeed, most of biochemical parameters determinate the evidence of different responses by different concentration of Hg in the sediment (s1 and s2) and (3) plants can or not modify their lipid composition by Hg toxicity through the UPLC-MS methodology. This study demonstrated that both plant species restricted Hg uptake. However, the process was more efficient in H. portulacoides. Was observed differences in the amount of Hg accumulated by both species. Allocation patterns also differs between species. H. portulacoides showed different levels of Hg between leaves, stems and roots, while J. maritimus accumulated the higher levels of Hg in roots. The conjugation of both process, absorption and translocation resulted in similar Hg concentrations in stems and leaves and much higher Hg levels in J. maritimus roots. The results obtained demonstrate that Hg generated oxidative damage in the roots of both species and in leaves of H. portulacoides. Differences in LPO between species obtaining for each specie reflects not only the level of Hg accumulated and Hg distribution but also the ability to trigger the defense mechanisms. J. maritimus was able to increase the protein levels and DHAR activity in roots and rhizomes and GSTs in rhizomes. H. portulacoides was not able to induce the antioxidant enzymatic responses. Although in leaves antioxidant molecules such carotenoids and őĪ-tocopherol were enhanced. In lipidome study, species also showed differences. In H. portulacoides, phospholipids decreased in all the organs analyzed, which can subject an alteration of membrane permeability. In addition, galactolipids decreased, reducing the efficiency on photosynthesis. However, őĪ-tocopherol increased, and so better protection to chloroplast membranes and maintenance of photosynthetic activity provided. In J. maritimus, lipid changes were only detected in roots and rhizomes, increasing lipid permeability and explaining the higher bioaccumulation at high Hg concentrations. Phyto sterols decreased significantly in roots and lead to alterations of permeability membrane. őĪ-tocopherol was detected in both organs of J. maritimus, a decrease that demonstrate an ineffective Hg contamination. This study may be a starting point for further work, namely in other marshes, in other species and with other metals. Understanding the mechanisms inherent to in heavy metal tolerance in marsh plants and the changes in lipid composition are important to detect the impact of metals in these ecosystems.Os sapais, considerados um dos ecossistemas mais produtivos, servem como reservat√≥rio para contaminantes, nomeadamente metais provenientes de industrias, reduzindo desta forma a contamina√ß√£o dos ecossistemas circundantes. Em ambiente aqu√°tico, a polui√ß√£o por merc√ļrio (Hg) √© principalmente devido a descargas de efluentes de industrias contendo concentra√ß√Ķes elevadas deste metal. O merc√ļrio √© reconhecido como sendo um metal pesado e extremamente t√≥xico para as plantas, interferindo desta forma em v√°rios processos celulares cruciais. Este estudo evidenciou a import√Ęncia de compreender o processo aquando da exposi√ß√£o das plantas ao merc√ļrio e desta forma avaliar o impacto da toxicidade do Hg nas comunidades de sapais. Uma melhor compreens√£o sobre estes aspetos de acumula√ß√£o avaliar√° o stress imposto pelo Hg sobre a produ√ß√£o prim√°ria em plantas de sapal e a adapta√ß√£o das plantas no ecossistema. Adicionalmente este estudo permite tamb√©m a interpreta√ß√£o dos mecanismos moleculares da toler√Ęncia ao merc√ļrio das plantas uma vez que estas s√£o importantes para uma limpeza eficiente dos sistemas contaminados por Hg para uma restaura√ß√£o efetiva. Desta forma, o trabalho incidiu em duas esp√©cies de plantas hal√≥fitas, Halimione portulacoides e Juncus maritimus recolhidas em dois locais da Ria de Aveiro contaminados por merc√ļrio, s1 considerado como o local menos contaminado e s2 como o local mais contaminado. Este estudo foi projetado para (1) avaliar como a distribui√ß√£o de Hg em plantas (2) de que forma as plantas iram reter a toxicidade do Hg desencadeando respostas antioxidantes. De fato, a maioria dos par√Ęmetros bioqu√≠micos determinaram a evid√™ncia de respostas diferentes por concentra√ß√Ķes diferentes de Hg no sedimento (s1 e s2) e (3) as plantas poderiam ou n√£o modificar sua composi√ß√£o lip√≠dica por toxicidade de Hg atrav√©s da metodologia UPLC-MS. Este estudo demonstrou que ambas as esp√©cies de plantas restringiam a absor√ß√£o de Hg. No entanto, o processo foi mais eficiente em H. portulacoides. Foram observadas diferen√ßas na quantidade de Hg acumulada por ambas as esp√©cies. Os padr√Ķes de aloca√ß√£o tamb√©m diferem entre as esp√©cies. H. portulacoides apresentou diferentes n√≠veis de Hg entre folhas, caules e ra√≠zes, enquanto J. maritimus acumulou os n√≠veis mais elevados de Hg nas ra√≠zes. A conjuga√ß√£o dos processos, absor√ß√£o e transloca√ß√£o resultou em concentra√ß√Ķes semelhantes de Hg em caules e folhas e n√≠veis de Hg muito elevados em ra√≠zes de J. maritimus. Os resultados obtidos demonstram que o Hg gerou danos oxidativos nas ra√≠zes de ambas as esp√©cies e nas folhas de H. portulacoides. As diferen√ßas na LPO entre esp√©cies que se obteve refletem n√£o apenas o n√≠vel de Hg acumulado e distribui√ß√£o de Hg, mas tamb√©m a capacidade de desencadear mecanismos de defesa. J. maritimus foi capaz de aumentar os n√≠veis proteicos e atividade DHAR em ra√≠zes e rizomas e GSTs em rizomas. H. portulacoides n√£o conseguiu induzir respostas enzim√°ticas antioxidantes. Contudo, nas folhas as mol√©culas antioxidantes como carotenoides e őĪ-tocoferol foram aumentadas. No estudo do lipidoma, as esp√©cies tamb√©m apresentaram diferen√ßas. Em H. portulacoides, os fosfol√≠pidos diminu√≠ram em todos os √≥rg√£os analisados, o que pode sugerir a altera√ß√£o da permeabilidade da membrana. Al√©m disso, os galactol√≠pidos diminu√≠ram a efici√™ncia na fotoss√≠ntese. No entanto, o őĪ-tocoferol aumentou, proporcionando assim uma melhor prote√ß√£o √†s membranas de cloroplastos e manuten√ß√£o da atividade fotossint√©tica. Em J. maritimus, as altera√ß√Ķes lip√≠dicas s√≥ foram detetadas em ra√≠zes e rizomas, aumentando a permeabilidade lip√≠dica e explicando a maior bioacumula√ß√£o de concentra√ß√Ķes elevadas de Hg. Os fito-ester√≥is diminu√≠ram significativamente nas ra√≠zes e levaram a altera√ß√Ķes da membrana de permeabilidade. O őĪ-tocoferol diminuiu em ambos os √≥rg√£os de J. maritimus, demonstrando a inefici√™ncia para a contamina√ß√£o por Hg. Este estudo pode ser um ponto de partida para novos trabalhos, nomeadamente em outros sapais, em outras esp√©cies e com outros metais. Compreender os mecanismos inerentes √† toler√Ęncia de metais pesados em plantas de sapais e as mudan√ßas na composi√ß√£o lip√≠dica s√£o importantes para detetar o impacto dos metais nestes ecossistemas

    Potencial enzimático de fungos filamentosos em pré-tratamento de borras de café para fermentação acidogénica

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    With resource depletion and increasing waste production, lignocellulosic biomass has been studied as biorefinery substrates. Due to its characteristics, spent coffee grounds (SCG) can be applied in numerous bioprocesses, such as the production of short-chain organic acids (SCOA). SCOA are versatile and high valued metabolites that can be produced by Acidogenic Fermentation (AF) as an alternative to the petrochemical process. To enhance AF competitiveness is necessary to improve the hydrolysis rate which can be achieved by enzymatic or chemical hydrolysis. Enzymatic hydrolysis is considered a more sustainable alternative. However, enzymes are costly, and consequently, chemical hydrolysis is the preferred option. Since the used substrate represents a huge cost in enzyme production, new strategies are necessary. One possibility is the use of organic wastes. These cheap substrates can contribute to reducing production costs. In this work, the sole effect of SCG (0.4 and 1.0% w/v) and the combined effect of SCG and pineapple peel (PP) (0.4 + 0.2% w/v and 1.0 + 0.4% w/v) were studied as inducers for enzyme production by Trametes versicolor and Paecilomyces variotii. In the assay with 0.4% SCG, a laccase activity in T. versicolor of 350 U/L was recorded. Posteriorly, the enzymatic extracts obtained were used for SCG pretreatment. To select the best pretreatment for SCOA production, AF was performed with SCG submitted to different physicochemical and biological pretreatments. Generally, the main SCOA produced were acetic, and propionic acids. Acid hydrolysis led to the highest SCOA concentration (2.52 g COD/L) but submerged fermentation by T. versicolor led to a similar SCOA concentration (2.44 g COD/L) and higher acidification degree (48.0%). The obtained results showed the great potential of T. versicolor enzymes for SCG pretreatment. The experiments performed allowed us to conclude that SCG can be potentially used as a laccase inducer and as a substrate for SCOA production, however, these processes must be optimized to become more competitive.Com a deple√ß√£o de recursos e o aumento da produ√ß√£o de res√≠duos, v√°rios materiais lenhocelul√≥sicos, t√™m sido estudados como potencias substratos para biorrefinarias. Pelas suas caracter√≠sticas, as borras de caf√© (SCG), podem ser aplicadas em v√°rios processos tais como a produ√ß√£o de √°cidos org√Ęnicos de cadeia curta (SCOA). Os SCOA s√£o metabolitos vers√°teis e de elevado valor, que podem ser produzidos por fermenta√ß√£o acidog√©nica (AF) em alternativa √† produ√ß√£o petroqu√≠mica. Para aumentar a competitividade da AF √© necess√°rio melhorar a taxa de hidr√≥lise do substrato, seja ela qu√≠mica ou enzim√°tica. A hidr√≥lise enzim√°tica √© a escolha mais sustent√°vel, no entanto, as enzimas est√£o associadas a elevados custos e, consequentemente, a hidr√≥lise qu√≠mica √© a op√ß√£o preferida. Dado que os custos de produ√ß√£o de enzimas est√£o maioritariamente associados √† mat√©ria prima utilizados, t√™m sido estudadas novas estrat√©gias. Uma delas √© a utiliza√ß√£o de res√≠duos org√Ęnicos como substratos baratos com o intuito de reduzir os custos de produ√ß√£o e otimizar os processos. Neste trabalho, estudou-se o efeito individual de SCG (0.4 e 1.0% w/v) e o efeito combinado de SCG e casca de anan√°s (PP) (0.4 + 0.2% w/v e 1.0 + 0.4% w/v) para a produ√ß√£o de enzimas por Trametes versicolor e Paecilomyces variotii, tendo sido obtida atividade m√°xima de lacase 350 U/L no ensaio de T. versicolor com 0.4% (w/v) SCG. Posteriormente, os extratos enzim√°ticos obtidos foram utilizados no pr√©-tratamento de SCG. Realizou-se AF com SCG submetidas a diferentes pr√©-tratamentos f√≠sico-qu√≠micos e biol√≥gicos de modo a selecionar o melhor pr√©-tratamento para a produ√ß√£o de SCOA. De uma forma geral, os SCOA maioritariamente produzidos foram os √°cidos ac√©tico e propi√≥nico. A maior concentra√ß√£o de SCOA (2.52 g COD/L) foi obtida com hidr√≥lise √°cida, mas a fermenta√ß√£o submersa de T. versicolor levou a uma concentra√ß√£o similar de SCOA (2.44 g COD/L) e maior grau de acidifica√ß√£o (48.0%). Os resultados obtidos permitiram concluir que as SCG t√™m potencial como indutores e substratos para a produ√ß√£o de lacase e de SCOA, no entanto estes processos dever√£o ser otimizados para que se tornem mais competitivos.Mestrado em Biotecnologi

    Environmental impact assessment of waste incorporation in road paving materials

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    Tese de doutoramento em Gest√£o e Tratamento de Res√≠duosO sector da constru√ß√£o civil √© uma das atividades que mais recursos consome. Estudos de valoriza√ß√£o de res√≠duos por incorpora√ß√£o em materiais de constru√ß√£o revestem-se de extrema pertin√™ncia e oportunidade pela redu√ß√£o da extra√ß√£o de mat√©ria-prima e dos impactes associados √† deposi√ß√£o de res√≠duos em aterros. Assim, o objetivo principal deste trabalho foi o de avaliar os impactes ambientais da incorpora√ß√£o de res√≠duos de diferentes setores da ind√ļstria na constru√ß√£o de camadas betuminosas, como substitutos parciais dos agregados naturais normalmente utilizados. Deste modo, foram estudadas misturas betuminosas de desgaste e de liga√ß√£o/base convencionais e outras com incorpora√ß√£o de res√≠duos - 75% de esc√≥ria de aciaria, 5% a 12% de areias de fundi√ß√£o, 3% lamas de corte de pedra, 2% de polietileno reticulado e 50% de material fresado. As misturas convencionais serviram como refer√™ncia. Foram realizados ensaios de caracteriza√ß√£o mec√Ęnica e ambiental dos agregados reciclados e das respetivas misturas betuminosas e foi constru√≠do um trecho experimental incorporando esc√≥ria de aciaria, a fim de avaliar o seu comportamento em escala real. Para calcular os impactes ambientais destas solu√ß√Ķes de pavimenta√ß√£o foi igualmente realizada uma avalia√ß√£o de ciclo de vida, com base em diferentes cen√°rios de dimensionamento de pavimentos, assim como uma avalia√ß√£o econ√≥mica. Entre os principais resultados, observou-se que as misturas com esc√≥ria de aciaria obtiveram o melhor desempenho mec√Ęnico. A mistura AC 14 com areia de fundi√ß√£o demostrou ser bastante promissora, com resultados ligeiramente superiores aos da mistura padr√£o. J√° as misturas AC20 com res√≠duos de lama demostraram ser mais fr√°geis do que a convencional. No trecho experimental, observou-se que em rela√ß√£o √† convencional, as misturas com esc√≥ria tiveram resultados superiores de sensibilidade √† √°gua e deforma√ß√£o permanente e inferiores de fadiga, devido ao seu elevado volume de vazios. Na avalia√ß√£o de ciclo de vida, as misturas com esc√≥ria e com material fresado obtiveram os melhores desempenhos ambientais. A mistura com areia de fundi√ß√£o e polietileno reticulado obtiveram resultados satisfat√≥rios, com n√≠veis de emiss√Ķes inferiores aos da mistura padr√£o. A mistura com lamas obteve o pior desempenho ambiental. Pode concluir-se que, do ponto de vista dos impactes ambientais e da caracteriza√ß√£o mec√Ęnica, a mistura com esc√≥ria √© a melhor alternativa, seguida pela mistura com fresado e pelas misturas com areia de fundi√ß√£o e com polietileno. Contudo a mistura com lamas n√£o apresentou desempenhos satisfat√≥rios a n√≠vel ambiental e mec√Ęnico, para tornar a constru√ß√£o mais sustent√°vel.The construction sector is one of the most resource-intensive activities. Studies of waste recovery by incorporation in building materials are extremely relevant and opportune for reducing the extraction of raw materials and the impacts associated with waste landfilling. Thus, the main objective of this work was to evaluate the environmental impacts of the incorporation of wastes from different industry sectors in the construction of asphalt layers, as partial substitutes for commonly used natural aggregates. Thus, conventional asphalt mixtures and others incorporating wastes - 75% steel slag, 5% to 12% foundry sands, 3% stone sludge, 2% cross-linked polyethylene and 50% reclaimed asphalt pavement material were studied for surface and binder/base courses. The conventional mixtures served as a reference. Mechanical and environmental characterization tests of the recycled aggregates and their asphalt mixtures were carried out and an experimental section was built incorporating steel slag, in order to evaluate its behavior on a full scale trial. To calculate the environmental impacts of these paving solutions, a life-cycle assessment was also performed, based on different pavement design scenarios, as well as an economic assessment. Among the main results, it was observed that the steel slag mixtures obtained the best mechanical performance. Mixture AC 14 with foundry sand has shown to be relatively promising, with results slightly better than those of the reference mixture. AC20 mixtures with stone sludge showed to be more fragile than the conventional mixture. In the field trial, it was observed that compared to the conventional mixtures, the steel slag mixtures had superior results of water sensitivity and permanent deformation and lower fatigue resistance, due to their high voids content. In the life-cycle assessment, the steel slag and reclaimed asphalt mixtures obtained the best environmental performances. The mixtures with foundry sand and cross-linked polyethylene produced satisfactory results, with lower emission levels than the reference mixture. The mixture with sludge obtained the worst environmental performance. It can be concluded that, from the environmental impacts and mechanical performance points of view, the steel slag mixture is the best alternative, followed by the reclaimed asphalt mixture and the foundry sand and polyethylene mixtures. However, sludge mixing did not perform satisfactorily at the environmental and mechanical levels, to make road construction more sustainable
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