N-methylation of macrocyclic hexaaminecobalt(III) complexes

Reaction between formaldehyde and the pendant arm macrocyclic complex (trans-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine)cobalt(III) [CoL1](3+) yielded the diimine derivative trans-6,13-dimethyl-6.13-bis(methyleneamino)-1,4,8,11-tetraazacyclotetradecane (L-3) as its cobalt(III) complex. Reduction of the imines has been achieved with NaBH4 and the meso and rac cobalt(III) complexes of trans-6,13-dimethyl-6,13-bis(methylamino)-1,4,8,11-tetraazacyclotetradecane (L-5) have been prepared. Crystal structures of the macrocyclic complexes [CoL1][ClO4](3), [CoL3][ClO4](3) and meso-[CoL5][ClO4](3).2H(2)O were determined and some unusual structural, spectroscopic and electrochemical variations observed going from the parent hexaamine [CoL1](3+) to [CoL3](3+) (diimine) and ultimately to [CoL5](3+) (bis-N-methylated hexaamine).

Comprehensive structural characterization of MCM-41: From mesopores to particles

In the present work the meso- and macro-structural characteristics of the mesoporous adsorbent MCM-41 have been estimated with the help of various techniques. The structure is found to comprise four different length scales: that of the mesopores, the crystallites, the grains and of the particles. It was found that the surface area estimated by the use of small angle scattering techniques is higher, while that estimated by mercury porosimetry is much lower, than that obtained from gas adsorption methods. Based on the macropore characterization by mercury porosimetry, and the considerable macropore area determined, it is seen that the actual mesopore area of MCM-41 may be significantly lower than the BET area. TEM studies indicated that MCM-41 does not have an ideal mesopore structure; however, it may still be treated as a model mesoporous material for gas adsorption studies because of the large radius of curvature of the channels.

New porphyrins tailored as biodiesel fluorescent markers

This work reports the synthesis, characterization, and evaluation of new porphyrins tailored to become biodiesel fluorescent markers. The compounds were obtained by the synthetic modification of the commercially available porphyrin 5,10,15,20-meso-tetrakis(pentafluorophenyl)porphyrin (TPPF(20)) using ethanol and hexadecan-1-ol (cetylic alcohol) as nucleophilic reagents. The stability of the marked biodiesel fuel solutions was investigated every 15 days for a total period of 3 months, and under different storage temperature and light exposure condition, simulating the conventional stock conditions. The influence of the different substituents of the porphyrins on the fluorescence properties of the biodiesel fuel markers was also assessed. The resulting porphyrins were highly soluble in biodiesel fuel and displayed strong fluorescence characterized by two strong emission bands. The fluorescent markers did not affect the biodiesel physical properties and were stable in storage conditions for at least 3 months at a concentration of 4 ppm. The best storage condition was found to be absence of light and 6 degrees C; the limit of detection by photoluminescence technique had magnitude of 10(-13) mol L(-1). The synthesized porphyrins were characterized by nuclear magnetic resonance ((1)H-NMR and (19)F-NMR), mass spectrometry (HRMS), ultraviolet visible absorption spectroscopy, and photoluminescence spectroscopy. (C) 2011 Elsevier Ltd. All rights reserved.

Dextrin-microencapsulated porphyrin - Luminescent properties

Photophysical properties of porphyrins in aqueous solutions are strongly affected by aggregation. One possible solution to this problem is to encapsulate the porphyrin into polymeric spheres, to provide an environment where the photosensitizer can be administered in its monomeric form in such treatments as photodynamic therapy. Here we report the microencapsulation of the meso-tetrakis(4-sulphonatophenyl) porphyrin (TPPS4) photosensitizer by the ultrasonic spray-drying technique. The encapsulated TPPS4 was morphologically characterized by scanning electron microscopy, and its photophysical properties were studied and compared with those of a physical blend of dextrin and TPPS4. We Successfully encapsulated TPPS4 into dextrin microspheres, and the encapsulated photosensitizer displays higher luminescence intensity than that of the prepared physical blends.

Chitosan as a Bioadhesive Agent Between Porphyrins and Phospholipids in a Biomembrane Model

Porphyrins are currently used in photodynamic therapy as photosensitizers. In this paper we studied the interaction of two charged porphyrins, 5, 10, 15, 20-mesotetrakis(N-metyl-4-pyridyl) porphyrin, (TMPyP/chloride salt) cationic, and 5, 10, 15, 20-meso-tetrakis(sulfonatophenyl) porphyrin, (TPPS(4)/sodium salt) anionic, nanoassembled in phospholipid Langmuir monolayers and Langmuir-Blodgett films. Furthermore, we used chitosan to mediate the interaction between the porphyrins and the model membrane, aiming to understand the role of the polysaccharide in a molecular level. The effect of the interaction of the photosensitizers on the fluidity of the lipid monolayer was investigated by using dilatational surface elasticity. We also used photoluminescence (PL) spectroscopy to identify the porphyrins adsorbed in the phospholipid films. We observed an expansion of the monolayer promoted by the adsorption of the porphyrins into the lipid-air interface which was more pronounced in the case of TMPyP, as a consequence of a strong electrostatic interaction with the anionic monolayer. The chitosan promoted a higher adsorption of the porphyrins on the phospholipid monolayers and enabled the porphyrin to stay in its monomeric form (as confirmed by PL spectroscopy), thus demonstrating that chitosan can be pointed out as a potential photosensitizer delivery system in photodynamic therapy.

Driving mechanisms for groundwater flow and salt transport in a subterranean estuary

This paper presents field measurements and numerical simulations of groundwater dynamics in the intertidal zone of a sandy meso-tidal beach. The study, focusing on vertical hydraulic gradients and pore water salinities, reveals that tides and waves provide important forcing mechanisms for flow and salt transport in the nearshore aquifer. Such forcing, interacting with the beach morphology, enhances the exchange between the aquifer and ocean. The spatial and temporal variations of vertical hydraulic gradients demonstrate the complexity and dynamic nature of the processes and the extent of mixing between fresh groundwater and seawater in a subterranean estuary''. These results provide evidence of a potentially important reaction zone in the nearshore aquifer driven by oceanic oscillations. Land-derived contaminants may undergo important biogeochemical transformations in this zone prior to discharge.

2,6,,9-trioxabicyclo[3.3.1]nona-3,7-dienes and 2,4,6,8-tetraoxaadamantanes: Novel chiral spacer units in macrocyclic polyethers

The unusual chiral heterocyclic systems, trioxabicyclo[3.3.1]nona-3,7-dienes (bridged bisdioxines), are incorporated as novel spacer molecules into macrocyclic polyether ring systems of various sizes (8, 9 as well as 11-15) by cyclocondensation reaction of the! bisacid chloride 4b or bisesters 6,7 and 10, with several ethylene glycols. The 2:2 macrocycles 12-14 are obtained in approximately 50:50 mixtures of diastereomers. These conclusions are mainly based on HPLC data presented in Table I as well as X-ray analyses of (1R,5R)-8c (space group Pbca, a = 10.163(3) Angstrom, b = 18.999(4) Angstrom, c = 36.187(10) Angstrom, V = 6987(3) Angstrom(3), Z = 8, d(calc) = 1.218 g cm(-3), 6974 reflections, R = 0.0553.), mesolrac-11 (space group P (1) over bar, a = 10.472(5) Angstrom, b = 16.390(5) Angstrom, c = 17.211(5) Angstrom, alpha = 98.69(2)degrees, beta = 93.04(2)degrees, gamma = 98.52(2)degrees, V = 2879.3(18) Angstrom(3), Z = 2, d(calc) = 1.173 g cm(-3), 11,162 reflections, R = 0.0945) and meso-12 (space group P2(1)/c, a = 9.927(2), b = 18.166(3), c = 17.820(3) Angstrom, beta = 96.590(10)degrees, V = 3192.3(10)Angstrom(3), Z = 4, D-c = 1.109 g cm(-3), 3490 reflections, R = 0.0646). The 1:1 macrocycles 8b,c are also formed by intramolecular transesterification of the open-chain bisesters 7b,c and their formation is favored by the use of metal ions as templates. The bridged bisdioxine moieties in 8b and 12 are converted into the corresponding chiral tetra-oxaadamantane spacers to afford macrocycles 16 and 17. Preliminary metal ion complexation studies with selected species (8c, 11-14) were also performed.

Porous solids from layered clays by combined pillaring and templating approaches

The pore structure formation in bentonite, pillared with a mixed sol of silicon and titanium hydroxides and treated subsequently with quaternary ammonium surfactants, is investigated. The surfactant micelles act as a template, similar to their role in MCM41 synthesis. Because both the surfactant micelles and the sol particles are positively charged, it is greatly favorable for them to form meso-phase assembles in the galleries between the clay layers that bear negative charges. Besides, the sol particles do not bond the clay layers strongly as other kinds of pillar precursors do, so that the treatment with surfactants can result in radical structure changes in sol-pillared clays. This allows us to tailor the pore structure of these porous clays by choice of surfactant. The surfactant treatment also results in profound increases in porosity and improvement in thermal stability. Therefore, the product porous clays have great potential to be Used to deal with large molecules or at high operating temperatures. We also found that titanium in these samples is highly dispersed in the silica matrix rather than existing in the form of small particles of pure titania. Such highly dispersed Ti active centers may offer excellent activities for catalytic oxidation reactions such as alkanes into alcohols and ketones.

Multi-scale modeling of the mechanical behavior of polymer-based materials

Polymers have become the reference material for high reliability and performance applications. In this work, a multi-scale approach is proposed to investigate the mechanical properties of polymeric based material under strain. To achieve a better understanding of phenomena occurring at the smaller scales, a coupling of a Finite Element Method (FEM) and Molecular Dynamics (MD) modeling in an iterative procedure was employed, enabling the prediction of the macroscopic constitutive response. As the mechanical response can be related to the local microstructure, which in turn depends on the nano-scale structure, the previous described multi-scale method computes the stress-strain relationship at every analysis point of the macro-structure by detailed modeling of the underlying micro- and meso-scale deformation phenomena. The proposed multi-scale approach can enable prediction of properties at the macroscale while taking into consideration phenomena that occur at the mesoscale, thus offering an increased potential accuracy compared to traditional methods.

Predicting the mechanical behavior of amorphous polymeric materials under strain through multi-scale simulation

Polymeric materials have become the reference material for high reliability and performance applications. However, their performance in service conditions is difficult to predict, due in large part to their inherent complex morphology, which leads to non-linear and anisotropic behavior, highly dependent on the thermomechanical environment under which it is processed. In this work, a multiscale approach is proposed to investigate the mechanical properties of polymeric-based material under strain. To achieve a better understanding of phenomena occurring at the smaller scales, the coupling of a finite element method (FEM) and molecular dynamics (MD) modeling, in an iterative procedure, was employed, enabling the prediction of the macroscopic constitutive response. As the mechanical response can be related to the local microstructure, which in turn depends on the nano-scale structure, this multiscale approach computes the stress-strain relationship at every analysis point of the macro-structure by detailed modeling of the underlying micro- and meso-scale deformation phenomena. The proposed multiscale approach can enable prediction of properties at the macroscale while taking into consideration phenomena that occur at the mesoscale, thus offering an increased potential accuracy compared to traditional methods.

Leishmaniose tegumentar americana no Estado do Acre, Brasil

OBJETIVO: Apresentar levantamento estatístico descritivo da leishmaniose tegumentar americana (LTA) no Estado do Acre. MÉTODOS: Os dados obtidos foram extraídos dos formulários da "Campanha Contra a Leishmaniose", no período de janeiro de 1992 a dezembro de 1997. As variáveis estudadas foram submetidas a análise estatística descritiva. RESULTADOS: O total de casos registrados foi de 2.557. Foi adotada a divisão do Acre em meso e microrregiões para apresentação dos resultados. A maior prevalência foi na microrregião de Brasiléia (231,8 casos/10.000 hab.). A forma clínica predominante foi cutânea (84,05%). A maior ocorrência foi no sexo masculino (71,02%). Portadores com idade de até 24 anos corresponderam a 50% dos casos. Há uma predominância nas ocupações rurais. O exame clínico foi usado para diagnosticar 83,97% dos casos. A maior média de tempo de espera para procurar tratamento médico foi registrada na mesorregião do Vale do Juruá (10,37 meses). CONCLUSÃO: Os altos índices de LTA cutâneo e cutâneo-mucosa encontrados sugerem a necessidade de serem feitas pesquisas sobre os reflexos psicossociais e para identificar fatores que influem na demora do tratamento dos casos.

Macrociclos tetrapirrólicos e produtos de contraste iodados: uma nova abordagem

O trabalho descrito no presente documento reporta a preparação de derivados tetrapirrólicos iodados de tipo porfirina tornando-os potenciais veículos a meio de contraste iodado, usado em radiodiagnóstico. Com os resultados deste trabalho irá ser realizado um pedido de patente das moléculas e portanto, o acesso a este trabalho será restrito nos termos do Código da Propriedade Industrial, aprovado pelo Decreto de Lei nº 36/2003 de 5 de Março. Na primeira fase do trabalho, foi sintetizado o derivado porfirínico simétrico, meso-substituído, contendo um total de 8 iodos. Este foi preparado por condensação do pirrol e do aldeído iodado em meio ácido e na presença de nitrobenzeno. Foram ainda preparados as respetivas metaloporfirinas contendo os iões metálicos de manganês e gadolínio. Posteriormente foi avaliada a capacidade destes derivados atenuarem o feixe de raio-X, através da mediação das Unidades de Hounsfield, após serem adquiridas imagens por Tomografia Computorizada. Na segunda fase do trabalho procedeu-se ao estudo da influência destes compostos na diferenciação celular, usando como modelo as células de pré-adipócitos 3T3-L1. Foi avaliada a diferenciação celular, através da quantificação de lípidos das células maduras, marcados com Red Oil O, por espectrofotometria de Visível 3 e 10 dias após a administração dos derivados em estudo.

Violência, escola e território: intervenção educativa em contextos urbanos complexos

Na presente comunicação apresentamos parte dos resultados de um estudo de caso desenvolvido pelos autores no âmbito do Observatório de Segurança Escolar (OSE). A investigação a que nos propusemos resulta do desenvolvimento e aprofundamento de estudos que a equipa do OSE tem vindo a realizar nos últimos 6 anos (Sebastião, Campos, Alves e Merlini: 2010; Sebastião, Campos e Merlini: 2011) e justifica-se pela necessidade de análises contextualizadas da problemática de violência na escola, no sentido de contribuir para futuras estratégias e mecanismos de intervenção e prevenção sobre esta forma de violência. Tendo como ponto de partida os dados estatísticos nacionais sobre os incidentes de violência nas escolas1, procurámos compreender como os traços identificados a nível nacional se traduzem e são reconfigurados territorialmente. Em particular, saber porque é que escolas situadas em territórios com condições sociais idênticas apresentam níveis de violência e abordagens de regulação diferenciadas. Partindo de uma abordagem meso analítica do fenómeno de violência na escola, que engloba as perspetivas organizacional (Burns e Flam: 2000; Mouzelis: 2000; Torres e Palhares: 2010; Lima: 2001) e ecológica (Fuchs: 2008; Machado: 2008; Carvalho, 2010; Leal: 2010), o estudo privilegiou uma estratégia metodológica intensiva e desenvolveu-se em três territórios do Concelho de Sintra. Nesta apresentação o foco analítico incide sobre as estratégias e mecanismos acionados pelas escolas nos processos de regulação (prevenção e intervenção) das ocorrências de violência na escola, considerando a diversidade de condições contextuais e organizacionais. Ou seja, analisamos o modo como as escolas respondem aos incidentes e procuram pacificar os seus quotidianos e as condições em que o fazem. Tendo em conta as possibilidades de ação encontradas, identificámos um conjunto de fatores significativos nos processos de regulação da violência, entre os quais destacamos: as lideranças e práticas organizacionais; as orientações para a intervenção e a importância da priorização da violência e os instrumentos para intervir, como a constituição de gabinetes de mediação de conflitos. Face às condições para agir, verificámos que as escolas demonstram ter margem para adequar, planear e implementar estratégias de resposta, adotando modalidades de resolução da conflitualidade/violência, diversificadas, independentemente desta ter origem, ou não, em condições externas à escola.

Seismic imaging of the western Iberian crust using ambient noise: Boundaries and internal structure of the Iberian Massif

We present new Rayleigh-wave dispersion maps of the western Iberian Peninsula for periods between 8 and 30 s, obtained from correlations of seismic ambient noise, following the recent increase in seismic broadband network density in Portugal and Spain. Group velocities have been computed for each station pair using the empirical Green's functions generated by cross-correlating one-day-length seismic ambient-noise records. The resulting high-path density allows us to obtain lateral variations of the group velocities as a function of period in cells of 0.5 degrees x 0.5 degrees with an unprecedented resolution. As a result we were able to address some of the unknowns regarding the lithospheric structure beneath SW Iberia. The dispersion maps allow the imaging of the major structural units, namely the Iberian Massif, and the Lusitanian and Algarve Meso-Cenozoic basins. The Cadiz Gulf/Gibraltar Strait area corresponds to a strong low-velocity anomaly, which can be followed to the largest period inverted, although slightly shifted to the east at longer periods. Within the Iberian Massif, second-order perturbations in the group velocities are consistent with the transitions between tectonic units composing the massif. (C) 2013 Elsevier B.V. All rights reserved.

Avaliação preliminar do potencial eólico com recurso a um modelo de Mesoescala

Mestrado em Engenharia Química. Ramo optimização energética na indústria química.