Magnetic properties of Co-doped TiO(2) anatase nanopowders

This letter reports on the magnetic properties of Ti(1-x)Co(x)O(2) anatase phase nanopowders with different Co contents. It is shown that oxygen vacancies play an important role in promoting long-range ferromagnetic order in the material studied in addition to the transition-metal doping. Furthermore, the results allow ruling out the premise of a strict connection between Co clustering and the ferromagnetism observed in the Co:TiO(2) anatase system.

A strategy to extend reactive distillation column performance under catalyst deactivation

This work addresses the effects of catalyst deactivation and investigates methods to reduce their impact on the reactive distillation columns performance. The use of variable feed quality and reboil ratio are investigated using a rigorous dynamic model developed in gPROMS and applied to an illustrative example, i.e., the olefin metathesis system, wherein 2-pentene reacts to form 2-butene and 3-hexene. Three designs and different strategies on column energy supply to tackle catalyst deactivation are investigated and the results compared.

Utilização de co-solventes na produção de biodiesel a partir de óleo residual e etanol por catálise enzimática

A constante e sistemática subida de preço dos combustíveis fósseis e as contínuas preocupações com o meio ambiente determinaram a procura de soluções ambientalmente sustentáveis. O biodiesel surge, então, como uma alternativa para essa problemática, bem como uma solução para resíduos líquidos e gordurosos produzidos pelo ser humano. A produção de biodiesel tem sido alvo de extensa atenção nos últimos anos, pois trata-se de um combustível biodegradável e não poluente. A produção de biodiesel pelo processo de transesterificação usando álcoois de cadeia curta e catalisadores químicos, nomeadamente alcalinos, tem sido aceite industrialmente devido à sua elevada conversão. Recentemente, a transesterificação enzimática tem ganho adeptos. No entanto, o custo da enzima permanece uma barreira para a sua aplicação em grande escala. O presente trabalho visa a produção de biodiesel por transesterificação enzimática a partir de óleo residual de origem vegetal. O álcool usado foi o etanol, em substituição do metanol usado convencionalmente na catálise homogénea, pois a atividade da enzima é inibida pela presença deste último. As maiores dificuldades apresentadas na etanólise residem na separação das fases (Glicerol e Biodiesel) após a reação bem como na menor velocidade de reação. Para ajudar a colmatar esta desvantagem foi estudada a influência de dois cosolventes: o hexano e o hexanol, na proporção de 20% (v/v). Após a escolha do co-solvente que permite obter melhor rendimento (o hexano), foi elaborado um planeamento fatorial no qual se estudou a influência de três variáveis na produção de biodiesel por catálise enzimática com etanol e co-solventes: a razão molar óleo/álcool (1:8, 1:6 e 1:4), a quantidade de co-solvente adicionado (30, 20 e 10%, v/v) e o tempo de reação (48, 36 e 24h). A avaliação do processo foi inicialmente seguida pelo rendimento da reação, a fim de identificar as melhores condições, sendo substituída posteriormente pela quantificação do teor de ésteres por cromatografia em fase gasosa. O biodiesel com teor de ésteres mais elevado foi produzido nas condições correspondentes a uma razão molar óleo:álcool de 1:4, com 5g de Lipozyme TL IM como catalisador, 10% co-solvente (hexano, v/v), à temperatura de 35 ºC durante 24h. O rendimento do biodiesel produzido sob estas condições foi de 73,3%, traduzido em 64,7% de teor de ésteres etílicos. Contudo o rendimento mais elevado que se obteve foi de 99,7%, para uma razão óleo/álcool de 1:8, 30% de co-solvente (hexano, v/v), reação durante 48h a 35 ºC, obtendo-se apenas 46,1% de ésteres. Por fim, a qualidade do biodiesel foi ainda avaliada, de acordo com as especificações da norma EN 14214, através das determinações de densidade, viscosidade, ponto de inflamação, teor de água, corrosão ao cobre, índice de acidez, índice de iodo, teor de sódio (Na+) e potássio (K+), CFPP e poder calorífico. Na Europa, os ésteres etílicos não têm, neste momento, norma que os regule quanto à classificação da qualidade de biodiesel. Contudo, o biodiesel produzido foi analisado de acordo com a norma europeia EN14214, norma esta que regula a qualidade dos ésteres metílicos, sendo possível concluir que nenhum dos parâmetros avaliados se encontra em conformidade com a mesma.

Ibuprofen-loaded poly(trimethylene carbonate-co-ϵ- caprolactone) electrospun fibres for nerve regeneration

The development of scaffolds that combine the delivery of drugs with the physical support provided by electrospun fibres holds great potential in the field of nerve regeneration. Here it is proposed the incorporation of ibuprofen, a well-known non-steroidal anti-inflammatory drug, in electrospun fibres of the statistical copolymer poly(trimethylene carbonate-co-ε-caprolactone) [P(TMC-CL)] to serve as a drug delivery system to enhance axonal regeneration in the context of a spinal cord lesion, by limiting the inflammatory response. P(TMC-CL) fibres were electrospun from mixtures of dichloromethane (DCM) and dimethylformamide (DMF). The solvent mixture applied influenced fibre morphology, as well as mean fibre diameter, which decreased as the DMF content in solution increased. Ibuprofen-loaded fibres were prepared from P(TMC-CL) solutions containing 5% ibuprofen (w/w of polymer). Increasing drug content to 10% led to jet instability, resulting in the formation of a less homogeneous fibrous mesh. Under the optimized conditions, drug-loading efficiency was above 80%. Confocal Raman mapping showed no preferential distribution of ibuprofen in P(TMC-CL) fibres. Under physiological conditions ibuprofen was released in 24h. The release process being diffusion-dependent for fibres prepared from DCM solutions, in contrast to fibres prepared from DCM-DMF mixtures where burst release occurred. The biological activity of the drug released was demonstrated using human-derived macrophages. The release of prostaglandin E2 to the cell culture medium was reduced when cells were incubated with ibuprofen-loaded P(TMC-CL) fibres, confirming the biological significance of the drug delivery strategy presented. Overall, this study constitutes an important contribution to the design of a P(TMC-CL)-based nerve conduit with anti-inflammatory properties.

Cobalt complexes with pyrazole ligands as catalyst precursors for the peroxidative oxidation of cyclohexane: Z-ray absorption spectroscopy studies and biological applications

[CoCl(-Cl)(Hpz(Ph))(3)](2) (1) and [CoCl2(Hpz(Ph))(4)] (2) were obtained by reaction of CoCl2 with HC(pz(Ph))(3) and Hpz(Ph), respectively (Hpz(Ph)=3-phenylpyrazole). The compounds were isolated as air-stable solids and fully characterized by IR and far-IR spectroscopy, MS(ESI+/-), elemental analysis, cyclic voltammetry (CV), controlled potential electrolysis, and single-crystal X-ray diffraction. Electrochemical studies showed that 1 and 2 undergo single-electron irreversible (CoCoIII)-Co-II oxidations and (CoCoI)-Co-II reductions at potentials measured by CV, which also allowed, in the case of dinuclear complex 1, the detection of electronic communication between the Co centers through the chloride bridging ligands. The electrochemical behavior of models of 1 and 2 were also investigated by density functional theory (DFT) methods, which indicated that the vertical oxidation of 1 and 2 (that before structural relaxation) affects mostly the chloride and pyrazolyl ligands, whereas adiabatic oxidation (that after the geometry relaxation) and reduction are mostly metal centered. Compounds 1 and 2 and, for comparative purposes, other related scorpionate and pyrazole cobalt complexes, exhibit catalytic activity for the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone under mild conditions (room temperature, aqueous H2O2). Insitu X-ray absorption spectroscopy studies indicated that the species derived from complexes 1 and 2 during the oxidation of cyclohexane (i.e., Ox-1 and Ox-2, respectively) are analogous and contain a Co-III site. Complex 2 showed low invitro cytotoxicity toward the HCT116 colorectal carcinoma and MCF7 breast adenocarcinoma cell lines.

Halogen-bonded tris (2,4-Bis(trichloromethyl)-1,3,5,triazapentadienato)-M(III) [M = Mn, Fe, Co] complexes and their catalytic activity in the peroxidative oxidation of 1-phenylethanol to acetophenone

One-pot template condensation of CCl3C=N with ammonia on a metal source [MnCl2 center dot 4H(2)O, FeCl3 center dot 6H(2)O or Co(CH3COO)(2)center dot 4H(2)O] in DMSO led to the formation of tris(2,4-bis(trichloromethyl)-1,3,5-triazapentadienato)-M(III) complexes, [M(NH=C(CCl3)NC(CCl3)=-NH}(3)]center dot n(CH3)(2)SO [M = Mn, n = 1 (1); M = Fe, n = 2 (2); M = Co, n = 2 (3)1, which were characterized using elemental analysis, and IR, ESI-MS and single-crystal X-ray analysis. The role of inter- and intramolecular non-covalent halogen and hydrogen bonds in the synthesis of 1-3 is discussed. It is shown that the crystal ionic radii of the metal ions [68.5 (Co) < 69 (Fe) < 72 (Mn), pm] are related to the corresponding Cl center dot center dot center dot Cl distances [3.178 (3) > 3.155 (2) > 3.133 (1) Al. Compounds 1-3 and the related di(triazapentadienato)-Cu(v) complex [Cu(NH=C(CCl3)NC(CCl3)=NH}2]center dot 2(CH3)(2)SO (4) act as catalyst precursors for the additive-free microwave (MW) assisted homogeneous oxidation of 1-phenylethanol with tert-butylhydroperoxide (TBHP), leading to the formation of acetophenone with yields up to 99% and TONs up to 5.0 x 10(3) after 1 h of low power (10 W) MW irradiation.

Tetranuclear COPPER(II) complexes with macrocyclic and open-chain disiloxane ligands as catalyst precursors for hydrocarboxylation and oxidation of alkanes and 1-phenylethanol

Two new tetranuclear complexes [Cu-4(mu-O)(L-1)-Cl-4] and [Cu-4(mu(4)-O)(L-2)(2)Cl-4] (2), where H2L1 is a macrocyclic ligand resulting from [2+2] condensation of 2,6-diformy1-4-methylphanol (DFF) and 1,3-bis(aminopropy1)tetramethyldisiloxane, and HL2 is a 1:2 condensation product: of DFF with trimethylsilyl p-aminobenzoate, have been prepared. The structures of the products were established by Xray diffraction. The complexes have been characterised by FTIR, UV/Vis spectroscopy, ES1 mass-spectrometry and magnetic susceptibility measurements. The latter revealed that the letrftriuclear complexes can be descr bed as two ferromagnetically coupled dinuclear units, in which the two copper(II) ions interact antiferromacinetically. The ccimpi.iunds act as homogeneous catalyst precursors for a number of single-pot reactions, including (I) hydrocarbaxylation, with CO, H2O and K2S2O8, of a variety of linear and cyclic (n = 5-8) alkanes into the corresponding Cn+1 carboxylic acids, (ii) peroxidative oxidation of cyclohexane, and (iii) solvent-free microwave-assisted oxidation of 1-phenyletha.nol.

A system verification strategy based on the BST infrastructure

A good verification strategy should bring near the simulation and real functioning environments. In this paper we describe a system-level co-verification strategy that uses a common flow for functional simulation, timing simulation and functional debug. This last step requires using a BST infrastructure, now widely available on commercial devices, specially on FPGAs with medium/large pin-counts.

Danny e o profundo mar azul: introdução da técnica da Meisner em Portugal pela Below de Belt Teatro Co.: relatório de estágio

Relatório de Estágio submetidoà Escola Superior de Teatro e Cinemapara cumprimento dos requisitos necessários à obtenção do grau de Mestre em Artes Performativas- especialização em Teatro-Música

A many-core co-processor for embedded parallel computing on FPGA

Single processor architectures are unable to provide the required performance of high performance embedded systems. Parallel processing based on general-purpose processors can achieve these performances with a considerable increase of required resources. However, in many cases, simplified optimized parallel cores can be used instead of general-purpose processors achieving better performance at lower resource utilization. In this paper, we propose a configurable many-core architecture to serve as a co-processor for high-performance embedded computing on Field-Programmable Gate Arrays. The architecture consists of an array of configurable simple cores with support for floating-point operations interconnected with a configurable interconnection network. For each core it is possible to configure the size of the internal memory, the supported operations and number of interfacing ports. The architecture was tested in a ZYNQ-7020 FPGA in the execution of several parallel algorithms. The results show that the proposed many-core architecture achieves better performance than that achieved with a parallel generalpurpose processor and that up to 32 floating-point cores can be implemented in a ZYNQ-7020 SoC FPGA.

Pozzolanic activity of oil-refining catalyst: evaluation by electron and atomic microscopy

The reuse of waste fluid catalytic cracking (FCC) catalyst as partial surrogate for cement can reduce the environmental impact of both the oil-refinery and cement production industries [1,2]. FCC catalysts can be considered as pozzolanic materials since in the presence of water they tend to chemically react with calcium hydroxide to produce compounds possessing cementitious properties [3,4]. In addition, partial replacement of cement with FCC catalysts can enhance the performance of pastes and mortars, namely by improving their compressive strength [5,6]. In the present work the reaction of waste FCC catalyst with Ca(OH)2 has been investigated after a curing time of 28 days by scanning electron microscopy (SEM) with electron backscattered signal (BSE) combined with X-ray energy dispersive spectroscopy (EDS) carried out with a JEOL JSM 7001F instrument operated at 15 kV coupled to an INCA pentaFetx3 Oxford spectrometer. The polished cross-sections of FCC particles embedded in resin have also been evaluated by atomic force microscopy (AFM) in contact mode (CM) using a NanoSurf EasyScan 2 instrument. The SEM/EDS results revealed that an inward migration of Ca occurred during the reaction. A weaker outward migration of Si and Al was also apparent (Fig. 1). The migration of Ca was not homogeneous and tended to follow high-diffusivity paths within the porous waste FCC catalyst particles. The present study suggests that the porosity of waste FCC catalysts is key for the migration/reaction of Ca from the surrounding matrix, playing an important role in the pozzolanic activity of the system. The topography images and surface roughness parameters obtained by atomic force microscopy can be used to infer the local porosity in waste FCC catalyst particles (Fig. 2).

Continuous catalyst free production of biodiesel from agro industrial waste with green solvents

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica

Parallel run-time for CO-OPN

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Conceção de um tutorial de Iniciação ao co-projeto de Hardware/software

A crescente evolução dos dispositivos contendo circuitos integrados, em especial os FPGAs (Field Programmable Logic Arrays) e atualmente os System on a chip (SoCs) baseados em FPGAs, juntamente com a evolução das ferramentas, tem deixado um espaço entre o lançamento e a produção de materiais didáticos que auxiliem os engenheiros no Co- Projecto de hardware/software a partir dessas tecnologias. Com o intuito de auxiliar na redução desse intervalo temporal, o presente trabalho apresenta o desenvolvimento de documentos (tutoriais) direcionados a duas tecnologias recentes: a ferramenta de desenvolvimento de hardware/software VIVADO; e o SoC Zynq-7000, Z-7010, ambos desenvolvidos pela Xilinx. Os documentos produzidos são baseados num projeto básico totalmente implementado em lógica programável e do mesmo projeto implementado através do processador programável embarcado, para que seja possível avaliar o fluxo de projeto da ferramenta para um projeto totalmente implementado em hardware e o fluxo de projeto para o mesmo projeto implementado numa estrutura de harware/software.

Robots and humans as co-workers? The human-centred perspective of work with autonomous systems

The design of work organisation systems with automated equipment is facing new challenges and the emergence of new concepts. The social aspects that are related with new concepts on the complex work environments (CWE) are becoming more relevant for that design. The work with autonomous systems implies options in the design of workplaces. Especially that happens in such complex environments. The concepts of “agents”, “co-working” or “human-centred technical systems” reveal new dimensions related to human-computer interaction (HCI). With an increase in the number and complexity of those human-technology interfaces, the capacities of human intervention can become limited, originating further problems. The case of robotics is used to exemplify the issues related with automation in working environments and the emergence of new HCI approaches that would include social implications. We conclude that studies on technology assessment of industrial robotics and autonomous agents on manufacturing environment should also focus on the human involvement strategies in organisations. A needed participatory strategy implies a new approach to workplaces design. This means that the research focus must be on the relation between technology and social dimensions not as separate entities, but integrated in the design of an interaction system.