Incorporation of niobium in SAPO-11 materials: Synthesis and characterization

The present work concerns a new synthesis approach to prepare niobium based SAPO materials with AEL structure and the characterization ofNb species incorporated within the inorganic matrixes. The SAPO-11 materials were synthesized with or without the help of a small amine, methylamine (MA) as co-template, while Nb was added directly during the preparation of the initial gel. Structural, textural and acidic properties of the different supports were evaluated by XRD, TPR, UV-Vis spectroscopy, pyridine adsorption followed by IR spectroscopy and thermal analyses. Pure and well crystalline Nb based SAPO-11 materials were obtained, either with or without MA, using in the initial gel a low Si content of about 0.6. Increasing the Si content of the gel up to 0.9 led to an important decrease of the samples crystallinity. Niobium was found to incorporate the AEL pores support as small Nb2O5 oxide particles and also as extra framework cationic species (Nb5+), compensating the negative charges from the matrix and generating new Lewis acid sites. (C) 2011 Elsevier Inc. All rights reserved.

Resultados preliminares de um estudo sobre tradução audiovisual infanto-juvenil: o caso da dobragem em Portugal

Nos últimos anos, o volume de produções audiovisuais aumentou exponencialmente graças ao desenvolvimento das novas tecnologias e à omnipresença dos mass media à escala global. No que concerne o público infanto- juvenil, o consumo massivo de produtos audiovisuais contribuiu para a construção de um novo tipo de espectador mais familiarizado com a imagem/palavra em movimento, seja no ecrã da televisão ou do computador. Com este artigo, pretendo partilhar os resultados preliminares de um estudo exploratório sobre o impacto da dobragem em Portugal no público infanto- juvenil enquanto consumidores/receptores deste tipo de tradução interlinguística. Considerando que a oferta televisiva é condicionante do tipo de consumo de produtos audiovisuais traduzidos é crucial compreender de que modo esta conjuntura poderá vir a criar públicos mais receptivos à dobragem num futuro próximo.

Copper(II) aza-bis(oxazoline) complex immobilized onto ITQ-2 and MCM-22 based materials as heterogeneous catalysts for the cyclopropanation of styrene

A copper(II) chiral aza-bis(oxazoline) homogeneous catalyst (CuazaBox) was anchored onto the external surface of MCM-22 and ITQ-2 structures, as well as encapsulated into hierarchical MCM-22. The transition metal complex loading onto the porous solids was determined by ICP-AES and the materials were also characterized by elemental analysis (C, N, H, S), FTIR, XPS, TG and low temperature N-2 adsorption isotherms. The materials were tested as heterogeneous catalysts in the benchmark reaction of cyclopropanation of styrene to check the effect of the immobilization procedure on the catalytic parameters, as well as on their reutilization in several catalytic cycles. Catalyst CuazaBox anchored onto the external surface of MCM-22 and ITQ-2 materials were more active and enantioselective in the cyclopropanation of styrene than the corresponding homogeneous phase reaction run under similar experimental conditions. This is due to the propylation of the acidic aza-Box nitrogen. HMCM-22 was nevertheless the best heterogeneous catalyst. Encapsulation of CuazaBox on post-synthesis modified MCM-22 materials led to low activities and enantioselectivities. But reversal on the stereochemical course of the reaction was observed, probably due to confinement effect. (C) 2013 Elsevier Inc. All rights reserved.

Produção de sentido na linguagem audiovisual através da montagem

Este texto é sobre os problemas e as soluções associadas com a produção de sentido de modo cinematográfico nos discursos audiovisuais. O enfoque centra-se na resposta à pergunta de como o texto e leitor criam o sentido e não tanto em qual é o significado do texto. Associado a este objectivo propomos identificar os limites expressivos do discurso cinematográfico que não recorre à verbalização e as capacidades que a linguagem cinematográfica tem vindo a desenvolver para exprimir conceitos cada vez mais complexos apesar de a representação visual estar limitada ao registo visual de objectos, pessoas e acções. Este estudo insere-se no campo da retórica visual e da literacia visual que se dedicam ao estudo dos processos através dos quais se produz, manipula e interpreta sentido através das imagens. No entanto porque estamos a estudar um discurso que se organiza no tempo e que contêm a imagem, palavra e som podemos inserir este estudo na disciplina da Retórica cinematográfica que é uma área científica contida dentro da semiótica e que se dedica ao estudo sobre porquê e como é que o discurso audiovisual produz sentido. O motivo que deu origem a este estudo tem origem no ensino de cadeiras sobre linguagem audiovisual a alunos universitários que tiveram doze anos de alfabetização mas nunca reflectiram sobre como se exprimem ideias sem o uso da palavra uma vez que o principal objectivo da escolaridade é tornar os alunos capazes de saberem interpretar e expressarem-se através da linguagem verbal. A consequência deste processo de aprendizagem é que quando se pede a uma pessoa com formação literária para se expressar num discurso audiovisual deparamos com filmes onde o sentido do discurso é feito com base no texto que é verbalizado numa voz off ou nos diálogos que são ditas por personagens de uma ficção.

Biomimetic norfloxacin sensors made of molecularly-imprinted materials for potentiometric transduction

A biomimetic sensor for norfloxacin is presented that is based on host-guest interactions and potentiometric transduction. The artificial host was imprinted into polymers made from methacrylic acid and/or 2-vinyl pyridine. The resulting particles were entrapped in a plasticized poly(vinyl chloride) (PVC) matrix. The sensors exhibit near-Nernstian response in steady state evaluations, and detection limits range from 0.40 to 1.0 μgmL−1, respectively, and are independent of pH values at between 2 and 6, and 8 and 11, respectively. Good selectivity was observed over several potential interferents. In flowing media, the sensors exhibit fast response, a sensitivity of 68.2 mV per decade, a linear range from 79 μM to 2.5 mM, a detection limit of 20 μgmL−1, and a stable baseline. The sensors were successfully applied to field monitoring of norfloxacin in fish samples, biological samples, and pharmaceutical products

Benzo[c]thiophene chromophores linked to cationic Fe and Ru derivatives for NLO materials: synthesis characterization and quadratic hyperpolarizabilities

5-Monocyclopentadienyliron(II)/ruthenium(II) complexes of the general formula [M(5-C5H5)(PP)(L1)][PF6] {M = Fe, PP = dppe; M = Ru, PP = dppe or 2PPh3; L1 = 5-[3-(thiophen-2-yl)benzo[c]thiophenyl]thiophene-2-carbonitrile} have been synthesized and studied to evaluate their molecular quadratic hyperpolarizabilities. The compounds were fully characterized by NMR, FTIR and UV/Vis spectroscopy and their electrochemical behaviour studied by cyclic voltammetry. Quadratic hyperpolarizabilities () were determined by hyper-Rayleigh scattering measurements at a fundamental wavelength of 1500 nm. Density functional theory calculations were employed to rationalize the second-order non-linear optical properties of these complexes.

Nanohybrid materials as transducer surfaces for electrochemical sensing applications

A nanohybrid electrochemical transducer surface was developed using carbon and gold nanomaterials. The strategy relayed on casting multiwalled carbon nanotubes or carbon nanofibers onto a screen-printed carbon electrode surface, followed by in situ generation of gold nanoparticles by electrochemical deposition of ionic gold, in a reproducible manner. These transducers, so fabricated, were characterized using both electrochemical and microscopic techniques. Biofunctionality was evaluated using the streptavidin-biotin interaction system as the biological reaction model. These platforms allow to achieve low detection limits (in the order of pmoles), are reproducible and stable at least for a month after their preparation, being a perfect candidate to be used as transducer of different sensor devices.

Natural waste materials containing chitin as adsorbents for textile dyestuffs: batch and continuous studies

In this work three natural waste materials containing chitin were used as adsorbents for textile dyestuffs, namely the Anodonta (Anodonta cygnea) shell, the Sepia (Sepia officinalis) and the Squid (Loligo vulgaris) pens. The selected dyestuffs were the Cibacron green T3G-E (CI reactive green 12), and the Solophenyl green BLE 155% (CI direct green 26), both from CIBA, commonly used in cellulosic fibres dyeing, the most used fibres in the textile industry. Batch equilibrium studies showed that the materials’ adsorption capacities increase after a simple and inexpensive chemical treatment, which increases their porosity and chitin relative content. Kinetic studies suggested the existence of a high internal resistance in both systems. Fixed bed column experiments performed showed an improvement in adsorbents’ behaviour after chemical treatment. However, in the column experiments, the biodegradation was the main mechanism of dyestuff removal, allowing the materials’ bioregeneration. The adsorption was strongly reduced by the pore clogging effect of the biomass. The deproteinised Squid pen (grain size 0.500–1.41 mm) is the adsorbent with highest adsorption capacity (0.27 and 0.037 g/g, respectively, for the reactive and direct dyestuffs, at 20ºC), followed by the demineralised Sepia pen and Anodonta shell, behaving like pure chitin in all experiments, but showing inferior performances than the granular activated carbon tested in the column experiments.

Molecularly-imprinted materials for potentiometric transduction: application to the antibiotic enrofloxacin

Enrofloxacin (ENR) is an antimicrobial used both in humans and in food producing species. Its control is required in farmed species and their surroundings in order to reduce the prevalence of antibiotic resistant bacteria. Thus, a new biomimetic sensor enrofloxacin is presented. An artificial host was imprinted in specific polymers. These were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. The potentiometric sensors exhibited a near-Nernstian response. Slopes expressing mVΔlog([ENR]/M) varied within 48–63. The detection limits ranged from 0.28 to 1.01 µg mL 1. Sensors were independent from the pH of test solutions within 4–7. Good selectivity was observed toward potassium, calcium, barium, magnesium, glycine, ascorbic acid, creatinine, norfloxacin, ciprofloxacin, and tetracycline. In flowing media, the biomimetic sensors presented good reproducibility (RSD of ±0.7%), fast response, good sensitivity (47 mV/Dlog([ENR]/ M), wide linear range (1.0×10-5–1.0×10-3 M), low detection limit (0.9 µg mL-1), and a stable baseline for a 5×10-2 M acetate buffer (pH 4.7) carrier. The sensors were used to analyze fish samples. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in vivo measurements of enrofloxacin or parent-drugs.

Selective recognition in potentiometric transduction of amoxicillin by molecularly imprinted materials

The indiscriminate use of antibiotics in foodproducing animals has received increasing attention as a contributory factor in the international emergence of antibiotic- resistant bacteria (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004). Numerous analytical methods for quantifying antibacterial residues in edible animal products have been developed over years (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004; Botsoglou and Fletouris in Handbook of food analysis, residues and other food component analysis, Marcel Dekker, Ghent, 2004). Being Amoxicillin (AMOX) one of those critical veterinary drugs, efforts have been made to develop simple and expeditious methods for its control in food samples. In literature, only one AMOX-selective electrode has been reported so far. In that work, phosphotungstate:amoxycillinium ion exchanger was used as electroactive material (Shoukry et al. in Electroanalysis 6:914–917, 1994). Designing new materials based on molecularly imprinted polymers (MIPs) which are complementary to the size and charge of AMOX could lead to very selective interactions, thus enhancing the selectivity of the sensing unit. AMOXselective electrodes used imprinted polymers as electroactive materials having AMOX as target molecule to design a biomimetic imprinted cavity. Poly(vinyl chloride), sensors of methacrylic acid displayed Nernstian slopes (60.7 mV/decade) and low detection limits (2.9×10-5 mol/L). The potentiometric responses were not affected by pH within 4–5 and showed good selectivity. The electrodes were applied successfully to the analysis of real samples.

New sensing materials of molecularly-imprinted polymers for the selective recognition of Chlortetracycline

As a result of the stressful conditions in aquaculture facilities there is a high risk of bacterial infections among cultured fish. Chlortetracycline (CTC) is one of the antimicrobials used to solve this problem. It is a broad spectrum antibacterial active against a wide range of Gram-positive and Gram-negative bacteria. Numerous analytical methods for screening, identifying, and quantifying CTC in animal products have been developed over the years. An alternative and advantageous method should rely on expeditious and efficient procedures providing highly specific and sensitive measurements in food samples. Ion-selective electrodes (ISEs) could meet these criteria. The only ISE reported in literature for this purpose used traditional electro-active materials. A selectivity enhancement could however be achieved after improving the analyte recognition by molecularly imprinted polymers (MIPs). Several MIP particles were synthesized and used as electro-active materials. ISEs based in methacrylic acid monomers showed the best analytical performance according to slope (62.5 and 68.6 mV/decade) and detection limit (4.1×10−5 and 5.5×10−5 mol L−1). The electrodes displayed good selectivity. The ISEs are not affected by pH changes ranging from 2.5 to 13. The sensors were successfully applied to the analysis of serum, urine and fish samples.

Luminol-doped nanostructured composite materials for chemiluminescent sensing of hydrogen peroxide

Silica based nanostructured composite materials doped with luminol and cobalt(II) ion were synthesized and characterized, resulting in a highly chemiluminescent material in the presence of hydrogen peroxide. A detection system with the CL light guided from the reaction tube to the photomultiplier tube using a one millimeter glass optical fiber was developed and assessed. A linear response was observed using a semi-logarithm calibration between 50–2000 µM hydrogen peroxide with 1 µM as the limit of detection.

Man-tailored biomimetic sensor of molecularly imprinted materials for the potentiometric measurement of oxytetracycline

A novel biomimetic sensor for the potentiometric transduction of oxytetracycline is presented. The artificial host was imprinted in methacrylic acid and/or acrylamide based polymers. Different amounts of molecularly imprinted and non-imprinted polymers were dispersed in different plasticizing solvents and entrapped in a poly(vinyl chloride) matrix. Only molecularly imprinted based sensors allowed a potentiometric transduction, suggesting the existence of host–guest interactions. These sensors exhibited a near-Nernstian response in steady state evaluations; slopes and detection limits ranged 42–63 mV/decade and 2.5–31.3 µg/mL, respectively. Sensors were independent from the pH of test solutions within 2–5. Good selectivity was observed towards glycine, ciprofloxacin, creatinine, acid nalidixic, sulfadiazine, cysteine, hydroxylamine and lactose. In flowing media, the biomimetic sensors presented good reproducibility (RSD of ±0.7%), fast response, good sensitivity (65 mV/decade), wide linear range (5.0×10−5 to 1.0×10−2 mol/L), low detection limit (19.8 µg/mL), and a stable baseline for a 5×10−3M citrate buffer (pH 2.5) carrier. The sensors were successfully applied to the analysis of drugs and urine. This work confirms the possibility of using molecularly imprinted polymers as ionophores for organic ion recognition in potentiometric transduction.

Audiovisual translation on Portuguese news bulletin

The daily access to news broadcast is something that, generally speaking, we do not abstain ourselves from, whether it is to be aware of what is going on in our country or to be informed about international events. But are we attentive to how the information about those events, namely those that occur outside Portugal, reaches us? How is that information handled – and who handles it – until we have it at our disposal? Is the audience aware that a large part of the news must be translated and must have a linguistic treatment? And how can we describe that same translation and the way it is presented? This case study is just an example of translation‘s role and its crucial presence on TV news broadcast, considering the way translation is processed, how it is barely noticed – or not –, how it influences the construction of the story and how the story influences the translation process. This case study was presented at the 2nd International Conference ―Media for All‖, with the theme ―Text on Air, Text on Screen‖, which took place at the Polytechnic Institute of Leiria, on 7-9 November 2007. O acesso diário a serviços informativos noticiosos é algo de que, de um modo geral, não nos privamos, seja para ficar a par do que se passa no nosso país, seja para ficarmos mais informados sobre eventos e acontecimentos internacionais. Mas teremos noção de como essas informações sobre esses acontecimentos, nomeadamente os que têm lugar fora de Portugal, chegam até nós? Qual será o tratamento dado a essas informações – e quem trata essas informações – até serem colocadas à nossa disposição? Será que o público, de um modo geral, se apercebe que grande parte das notícias é alvo de tratamento tradutológico e linguístico? E como se caracterizará essa tradução e a forma de apresentação da mesma? O presente estudo de caso é apenas um exemplo do papel e da presença fulcral da tradução em serviços noticiosos televisivos, seja pela forma como é feita, pelo modo como passa despercebida (ou não), pela influência que terá na construção da peça noticiosa e pela influência que a peça noticiosa terá no modo como se processa a tradução. Este estudo de caso foi apresentado na 2ª Conferência Internacional ―Media for All‖, subordinada ao tema ―Text on Air, Text on Screen‖, que teve lugar no Instituto Politécnico de Leiria de 7 a 9 de Novembro de 2007.

Bisphenol A migration from plastic materials: direct insight of ecotoxicity in Daphnia magna

Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) whose migration from food packaging is recognized worldwide. However, the real overall food contamination and related consequences are yet largely unknown. Among humans, children’s exposure to BPA has been emphasized because of the immaturity of their biological systems. The main aim of this study was to assess the reproductive impact of BPA leached from commercially available plastic containers used or related to child nutrition, performing ecotoxicological tests using the biomonitoring species Daphnia magna. Acute and chronic tests, as well as single and multigenerational tests were done. Migration of BPA from several baby bottles and other plastic containers evaluated by GC-MS indicated that a broader range of foodstuff may be contaminated when packed in plastics. Ecotoxicological test results performed using defined concentrations of BPA were in agreement with literature, although a precocious maturity of daphnids was detected at 3.0 mg/L. Curiously, an increased reproductive output (neonates per female) was observed when daphnids were bred in the polycarbonate (PC) containers (145.1±4.3 % to 264.7±3.8 %), both in single as in multigenerational tests, in comparison with the negative control group (100.3±1.6 %). A strong correlated dose-dependent ecotoxicological effect was observed, providing evidence that BPA leached from plastic food packaging materials act as functional estrogen in vivo at very low concentrations. In contrast, neonate production by daphnids cultured in polypropylene and non-PC bottles was slightly but not significantly enhanced (92.5±2.0 % to 118.8±1.8 %). Multigenerational tests also revealed magnification of the adverse effects, not only on fecundity but also on mortality, which represents a worrying trend for organisms that are chronically exposed to xenoestrogens for many generations. Two plausible explanations for the observed results could be given: a non-monotonic dose–response relationship or a mixture toxicity effect.