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A 3-D net based on weak metallophilic (Cu⋯Cu) interactions
No full textA novel 3-D binary copper(I) polymer [Cu(IN)]n (1, IN = isonicotinate)
has been solvothermally synthesized. 1-D [Cu(IN)] chains of
1 are interconnected by weak metallophilic (Cu⋯Cu) interactions
to form a 3-D net. The theoretical band structure and photocatalytic
and fluorescence properties have also been studied
A recyclable ionic liquid-oxomolybdenum(VI) catalytic system for the oxidative desulfurization of model and real diesel fuel
No full textThe oxidative desulfurization of model and real diesel has been studied using the complex [MoO2Cl2(4,4′-di-tert-butyl-2,2′-bipyridine)] as (pre)catalyst, aq. H2O2 as oxidant, and an ionic liquid as extraction solvent. Under moderate conditions (50 °C) and short reaction times (<3 h), dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene could be completely removed from the model diesel. The (pre)catalyst 1 was transformed in situ to the active catalyst [MoO(O2)2(di-tBu-bipy)]. By sequentially performing extractive desulfurization and ECODS steps, 76% sulfur removal was achieved for a real diesel (Sinitial = 2300 ppm). For both the model and real diesels, the catalyst/IL phase could be easily recycled and reused with no loss of desulfurization efficiency
Synthesis and properties of CuO-doped Ce0.9Gd0.1O2-delta electrolytes for SOFCs
No full textThe effects of copperoxide(CuO)addition on the crystal structure, densification and microstructure of Gddopedceria (Ce0.9Gd0.1O2 δ,
CGO) synthesized by the polymeric precursor method have been studied. Ce0.9 xGd0.1CuxO2 δ (0rxr0.01) precursorpowderswerecalcined
at 600 1C for 1 hand the phase formation was studied by powder Xray diffraction combined with Rietveld refinement analysis
Fraccionamento da cortiça e caracterização dos seus componentes: estudo de possibilidades de valorização da suberina
Full text linkDoutoramento em QuímicaA cortiça do Quercus suber L. apresenta grande importância económica para Portugal sendo
indispensável realizar estudos científicos que, de alguma forma, possam contribuir para o
desenvolvimento deste sector. Um dos aspectos com importância económica para o sector corticeiro
está relacionado com o aproveitamento dos desperdícios da cortiça sob a forma de matéria prima
rejeitada e de pó proveniente do processamento industriai. Tais desperdícios representam uma perda
significativa deste precioso material, não havendo por outro lado, estudos de carácter cientifico sobre o
seu aproveitamento.
Com o presente trabalho pretendeu-se investigar novas possibilidades de valorização dos
componentes da cortiça. Para atingir tal objectivo, impõe-se em primeiro lugar um conhecimento
profundo das propriedades químicas e fisicas da cortiça e dos seus constituintes. Para isso, a estratégia
seguida baseou-se em três linhas de orientação principais: i) caracterização química e fisico-química da
cortiça; ii) desenvolvimento de processos de kaccionamento viáveis no isolamento dos seus
constituintes; iii) estudo sistemático da estrutura química e das propriedades fisicas associadas ao seu
maior componente, suberina, com a Mdade de encontrar possíveis aplicações em diferentes áreas
tecnológicas. Assim:
1. A cortiça como material natural foi inicialmente caracterizada por FTIR, RMN de "C no
estado sólido, TGA, DSC e IGC. Os resultados da caracterização por FTIR, RMN de I3c no estado
sólido conlirmaram a natureza complexa deste material dominada pelo seu componente alifático
maioritáxi0 (suberina) possuindo grupos hidroxüicos e carboxíücos. A análise por RMN de "C revelou
a presença de dois domínios alifáticos diferentes, um possuindo uma baixa mobilidade (possivelmente
ligado à matriz lenhocelulósica) com ressonância a 33 ppm, e outro com uma maior mobilidade a 30
ppm. A caracterização por IGC revelou elevada energia de superficie e um carácter anfotérico, os quais
sugerem que a cortiça pode interagir favoravelmente com matrizes pohéricas ácidas e básicas. A
degradação térmica da cortiça, estudada por RMN de 13c no estado sólido, TGA e DSC, iniciou-se a
cerca de 150°C para os extractáveis e para a suberina nos pontos de ligação à parede celular. No
entanto, as principaís modificações da suberina e da lenhina tiveram lugar entre 200 e 350°C. Uma
kacção da suberina resistiu ?dei gradação térmica até 400°C, confirmando o pápel importante da
suberina na estabilidade térmica da cortiça.
Resumo iii
2. A composição química detalhada da cortiça foi determinada usando tanto métodos
convencionais como processos organosolv, mostrando-se estes últimos bastante promissores. Os
melhores resultados no fiaccionamento organosolv foram obtidos para misturas de etanol/água. As
condições de processamento tais como a proporção etanoUágua, temperatura, tipo de catalisador (ácido
ou básico e correspondentes quantidades) foram variadas no sentido de obter o máximo rendimento de
componentes extraídos. Estes rendimentos variaram entre 23% para a catálise ácida e 85% para o
NaOH. Dependendo das condições experimentais usadas, este processo torna-se mais ou menos
selectivo revelando indicações importantes acerca da natureza das associações entre os componentes na
morfologia da cortiça, as quais foram estudadas por FTIR e RMN de 13c no estado sólido.
3. Visando uma posterior extracção industrial da suberina a partir dos desperdícios da cortiça
estudou-se a extracção deste componente por metanólise alcalina com NaOH. A suberina extraída foi
exaustivamente caracterizada por diferentes técnicas químicas e físico-químicas. Assim, a caracterização
por FTIR em conjunto com a caracterização por RMN de I3c e 'H revelou que a suberina solubilizada
era composta por longas cadeias aiifáticas de hidroxiácidos essencialmente na forma de esteres
metilicos. A caracterização por GC-MS mostrou mais especificamente que este extracto era constituído
por cadeias entre C16 e C24 de w-hidroximonoácidos, a,w-diicidos, monoácidos simples e 1-alcanois,
os quais corresponderam no entanto a menos de metade da massa total de suberina. Uma outra fiacção
com elevados pesos moleculares até agora desconhecida foi também detectada e caracterizada por
VPO, MS e GPC. As propriedades da suberina extraída foram igualmente caracterizadas por técnicas
térmicas, morfológicas e reológicas usando diferentes métodos, tais como DSC, TGA, microscopia
óptica com luz polarizada, densidade, viscosidade, testes dinâmico-mecânicos e medidas de tack. Estas
análises revelaram a presença de partículas microcristab na suberina presentes numa matriz amorfa e
com intervalo de fusão entre O e 50°C. A suberina à temperatura ambiente apresentou um
comportamento plástico e tixotrópico com elevada viscosidade associada à relativamente elevada
energia de activação. Adicionalmente, a energia de supedcie da suberina foi também determinada por
medição de ângnlos de contacto, pelo método de WilheImy, pressão máxima de bolhas e IGC.
Um pohero semelhante à lenhina foi extraído pelo processo organosolv em meio ácido e
caracterizado por FTK RMN de 13c, oxidação por nitrobenzeno seguida de análise por HPLC, e
oxidação por pemianganato e análise dos produtos por GC-MS. Os resultados indicaram que este
pohero, livre de carbohidratos, era predominantemente constituído por urna fiacção aromática ligada
covalentemente a estruturas alifáticas da suberina e composta maioritariamente por unidades tipo
gnaiacíio juntamente com pequenas quantidades de unidades siringílo. Apresentou também baixo
Resumo iv
conteúdo em metoxilos mas quantidades significativas de unidades condensadas envolvendo
principalmente unidades tipo guaiacíio. Os resultados obtidos sugerem que na parede celular da cortiça
a lenh e a suberina aíifática se encontram covalentemente ligadas, ou dito de modo diferente, que a
chamada ftacção aromática da suberina será pelo menos parcialmente um polúnero do tipo lenhina.
Após o estudo exaustivo das características químicas e fisico-químicas da suberina passou-se
para o estudo dos seus possíveis usos tendo em vista alcançar o objectivo inicial deste trabalho - a
valorização dos excedentes da indústria corticeira. Dois domínios específicos foram seleccionados neste
contexto: a aplicação da suberina como macromonómero na síntese de uretanos e poliuretanos e como
aditivo em formulações de tintas de impressão.
Baseado no relativamente elevado conteúdo de OH, achou-se que a suberina seria um
interessante precursor na elaboração de novos materiais, sendo portanto estudada como potencial
macromonómero na síntese de uretanos e poliuretanos, usando mono- e di-isocianatos aromáticos e
aíifáticos. Este estudo foi iniciado pela investigação da cinética das reacções de policondensação com os
diferentes isocianatos. Estes processos mostram seguir um comportamento de segunda ordem sem
anomalias cinéticas ou mecânicas. Quando os mono-isocianatos foram usados na síntese os produtos
obtidos foram solúveis, tendo no entanto ocorrido ligações cruzadas no caso da utilização dos diisocianatos
com rendimento máximo dos produtos insolúveis ou reticulados para [NCO]I[OH] = 1. Os
produtos foram caracterizados por FTIR, RMN de 'H e DSC, estabelecendo relações est~turapropriedades
no que diz respeito a diferentes parâmetros como a temperatura de transição vítrea.
Concluiu-se deste estudo que a suberina pode ser utilizada como poli01 na formulação duma nova
fda de poliuretanos com propriedades interessantes em novas tecnologias de materiais.
Com a Wdade de estudar a aplicação da suberina como aditivo em composições típicas de
tintas de impressão offset, baseadas em óleos vegetais ou minerais, esta foi preparada como substracto e
as suas propriedades observadas. A adição da suberina a estas tintas provocou modifcações
significativas dos comportamento reológicos (viscosidade e energia de activação). A adição a uma tinta
para oEset sem solução de molhagem levou a uma modificação da compatibilidade entre os principais
componentes da tinta. Este facto poderá ter influência no comportamento de secagem da tinta após
impressão, facilitando assim a evaporação elou penetração do solvente. Quando a suberina foi
adicionada a uma tinta vegetal usada na impressão de jornais (elevada velocidade de impressão e
grandes tiragens), onde a secagem é efectuada por penetração do solvente da tinta no papel, houve um
decréscimo da coesão entre a tinta e o suporte de impressão, diminuindo assim a possibilidade de
arrastamento das fibras do papel e melhorando a secagem por penetração do solvente.
Resumo v
O trabalho global permitiu assim alcançar conclusões promissoras e abrir novas perspectivas
sobre o uso racional dos excedentes da industriais corticeua através da exploração das propriedades química e físicas únicas da suberina.Since cork of Quercus suber L. represents a major economic issue in Portugal, it seems
indispensable to carry out scientzc studies, witch could contribute in some ways, to help the
development of that sector. One of the critical aspects bearing a substantial economical impact to the
cork industry is related to a rational utilization of the by-products in the form of rejects at the source
and powders arising fkom processing. Little has been done in this area and the ensuing wastes represent
a net loss of a precious material. The present investigation aimed at finamg novel ways to overcome this
problem through a scientific approach requiring some fundamental knowledge of the starting material.
We felt that only thanks to a thorough understanding of the chemistry and the physical
properties of cork and its constituents should it be possible to approach the ultimate goal. For this, a
strategy was devised based on three phases, namely: i) a further insight into the chemical and physicalchemical
characterisation of cork; ii) the development of fiactionation procedures capable of providing
a viable route to the isolation of its various components; and iii) the systematic study of the chemical
structures and physical properties associated with its major component, suberin, in order to find
possible applications in dzerent domains. Thus,
1. Cork in its pristine state was first characterised by FTIR, Solid State 13c NMR, TGA, DSC
and IGC. The results of FTIR and Solid State 13C NMR analyses confumed the complex nature of this
natural material dominated by a major aliphatic component possessing both hydroxy and carboxy
groups. Solid State "C NMR spectra revealed the presence of two different aliphatic domains of
suberin, one possessing a low mobiity (possibly linked to the lignocellulosic matrix) and resonating
around 33 ppm and the other with a higher mobility resonating at 30 ppm. The IGC characterization
revealed a high surface energy and an amphoteric character which suggests that cork can interact
favourably with both acidic and basic polymeric matrices. The thermal degradation of cork, studied by
Solid State 13c NMR, TGA and DSC, started around 150°C for the soluble components and for suberin
linkage to the cell wall. However, the major modifications of suberin and lignin structures took place
between 200 and 350°C. A fkaction of suberin resisted to thermal degradation until 400°C coI1.tirming
the major role of suberin in cork thermal stability.
2. The detailed chemical composition of cork was established using both conventional methods
and organosolv processes, the latter approach being particularly profitable. The best agent for the
organosolv fiactionation called upon ethanollwater mixtures. Processing conditions like ethanoltwater
Abstract vii
proportions, temperature, catalysis (acid or basic and corresponding amounts) were varied in order to
achieve the highest proportion of extracted materials. These yields varied fiom 23% with acid catalysis
and 85% with NaOH. Depending on the conditions, the process varied in selectivity, revealing
important indications about the nature of associations among the components within the cork
moqhologg: which were then studied by FTIR and Solid State 13c NMR.
3. h view of a possible industrial extraction of suberin from cork wastes, the alkaline methanol
extracton with EdmOH was studied. The ensuing suberin was exhaustively characterized by different
chemical and physico-chemical techniques. Thus, FTIR together with 13c and 'H NMR revealed that the
solubiid suberin was composed of hydroxyacids with long aliphatic chains, essentially in the form of
methyl esters. GC-MS analyses showed more spec3cally that they were constituted of C16 to C24 ohy&
oxymonoacids, a,o-diacids, monoacids and I-alkanols, which corresponded however to less than
half of the subern total mass. Another fiaction with higher molecular weight unknown until now was
also detected and characterized by VPO, MS-CI and GPC. The properties of the extracted suberin were
examined by thermal, morphological and rheological means using different methods, such as DSC,
TGA, polarized light microscopy, density, viscosity, dynamic-mechanical testing and tack
measurements. These features revealed the presence of microcrystalline particles in suberin, witbin an
morphous rnsabrk, which melted between 0 and 50°C. Suberin at ambient temperature showed a plastic
and thtropic behaviour, a high viscosity associated with a relatively high activation energy to flow.
Additionally, the surface energy of suberin was also determined by contact angles measurements, the
Wiehy plate method, maximum bubble pressure and IGC.
A Em-like polymer was also extracted by an organosolv procedure using an acid medium and
chacterised by FTIR, I3c nitrobenzene oxidation followed by HPZC analysis, and
pemganate oxidation, followed by GC-MS analysis. The results showed that this polymer, fiee of
carbohydrate elements, was composed mainly of an aromatic fraction bound to aliphatic suberin-type
structures and bearing predominantly guaiacyl units together with small amounts of syringyl moieties. It
contained few methoxy groups, but significant amounts of condensed structures involving mainly
gmhcyl units. The results obtained suggest that in cork cell wall lignin and aliphatic suberin are
covdently bonded or, on another usage, that the so-called aromatic fiaction of suberin is, at less,
partidy m li@-&e polymer.
Mer this exhaustive study of the suberin chemical and physico-chemical characterisation, we
switched to an investigation of its possible use in materials technology in order to approach the original
rnim of this work -the valorisation of cork industry by-products. Two speci6c areas were selected in this
Abstract viii
context: its application as a macromonomer in the synthesis of urethanes and polyurethanes and its
utilisation as an additive in printing inks formulations.
Because of their relatively high OH content, suberin was found to be interesting precursor for
the elaboration of new materials, and was therefore thoroughly studied as potential macromonomers in
the synthesis of polyurethanes using aromatic and aliphatic mono and di-isocyanates. This study was
initiated by kinetic investigation of the corresponding polycondensation reactions with different
isocyanates. These processes were shown to follow a clear-cut second-order behaviour without any
kinetic or mechanistic anomalies. When mono-isocyanates were used, the products were soluble
whereas with di-isocyantes crosslinking occurred and the yield of insoluble products reached its highest
value with WCO]/[OH]=l. The products were characterised by FTIR, 'H NMR and DSC and
structure-properties relationships obtained with respect to parameters like the glass transition
temperature. It could be concluded that suberin can be used as a polyol in the formation of a new
family of polyurethanes with interesting properties.
In order to envisage a suberin application as additive in printing inks typical offset compositions
based on either vegetal or mineral diuents were prepared as basic substrates and their properties
assessed. The suberin addition to these inks lead to significant changes in the rheological features
(viscosity and activation energy). Suberin addition to a waterless ink gave rise to a change in
compatibility among the major ink components, which can be very important in the drying behaviour of
ink after printing, by facilitating the diluent evaporation andlor penetration. When suberin was added to
a vegetal ink used for newspaper printing (high printing velocity and large quantities), where drying
occurs mostly by solvent penetration into the uncoated paper, it gave rise to a decrease in the cohesion
between the ink and the paper surface which was beneficial in reducing fibre 'dragging and improving the solvent penetration process
Bioprospecting for lipophilic-like components of five Phaeophyta macroalgae from the Portuguese coast
No full textLipophilic compounds present in dichloromethane extracts of five brown macroalgae from the Portuguese coast were analyzed by gas chromatography-mass spectrometry (GC-MS). Their dicarboxylic acids, long-chain aliphatic alcohols, and monoglyceride profile are reported for the first time. Additionally, other new compounds were also first reported: 24-methylene-cholesterol in Himanthalia elongata, Laminaria ochroleuca, and Undaria pinnatifida; desmosterol and brassicasterol in H. elongata, L. ochroleuca, Sargassum muticum, and U. pinnatifida; fucosterol and campesterol in S. muticum; and cholest-5-en-3-ol-(3β)-3-phenyl-2-propenoate in Cystoseira tamariscifolia. Brown macroalgae dichloromethane extracts are mainly composed of fatty acids (463.4–3089.0 mg kg−1 of dry material) and sterols (75.5–442.7 mg kg−1 of dry material). High amounts of polyunsaturated fatty acids were found, with the ω-6/ω-3 ratios of all species lower than 3. Cystoseira tamariscifolia, H. elongata, and S. muticum showed to be also promising sources of fucosterol. These results seem to uphold the incorporation of these macroalgae in a more balanced diet, as well as their use in the nutraceutical industry, as long as they are coupled with sustainable management of these natural resources
Aqueous biphasic systems composed of ionic liquids and polypropylene glycol: insights into their liquid-liquid demixing mechanisms
No full textNovel ternary phase diagrams of aqueous biphasic systems (ABSs) composed of polypropylene glycol
with an average molecular weight of 400 g mol 1 (PPG-400) and a vast number of ionic liquids (ILs)
were determined. The large array of selected ILs allowed us to evaluate their tuneable structural
features, namely the effect of the anion nature, cation core and cation alkyl side chain length on the
phase behaviour. Additional evidence on the molecular-level mechanisms which rule the phase splitting
was obtained by 1H NMR (Nuclear Magnetic Resonance) spectroscopy and by COSMO-RS (Conductorlike
Screening Model for Real Solvents). Some systems, for which the IL PPG-400 pairs are completely
miscible, revealed to be of type ‘‘0’’. All data collected suggest that the formation of PPG IL-based ABSs
is controlled by the interactions established between the IL and PPG, contrarily to previous reports
where a ‘‘salting-out’’ phenomenon exerted by the IL over the polymer in aqueous media was proposed
as the dominant effect in ABS formation. The influence of temperature on the liquid liquid demixing
was also evaluated. In general, an increase in temperature favours the formation of an ABS in agreement
with the lower critical solution temperature (LCST) phase behaviour usually observed in polymer IL binary
mixtures. Partition results of a dye (chloroanilic acid, in its neutral form) further confirm the possibility of
tailoring the phases’ polarities of IL PPG-based ABSs
Quasilinear elliptic systems with measure data
No full textWe study the existence of solutions of quasilinear elliptic systems involving
equations and a measure on the right hand side, with the form
\left\{\begin{array}{ll}
-\sum_{i=1}^n \frac{\partial}{\partial x_i}\left(\sum\limits_{\beta=1}^{N}\sum\limits_{j=1}^{n}%
a_{i,j}^{\alpha,\beta}\left( x,u\right)\frac{\partial}{\partial x_j}u^\beta\right)=\mu^\alpha& \mbox{ in }\Omega ,\\
u=0 & \mbox{ on }\partial\Omega,
\end{array}\right.
where is the equation index, is an open bounded subset of , and is a finite Randon
measure on with values into . Existence of a solution is proved for two different sets of assumptions on . Examples are provided that satisfy our conditions, but do not satisfy conditions required on previous works on this matter
The EFFIS forest fire atmospheric emission model: application to a major fire event in Portugal
No full textForest fires are a major contributor of gaseous and particulate compounds to the atmosphere, impairing air quality and affecting human health. A new forest fire emissions module was developed and integrated into the European Forest Fire Information System (EFFIS), which systematically compiles, since 2000, series of burnt area statistics mapped from satellite imagery. This new forest fire emission model was built on classical methodologies of fuel-map based emission estimation that were improved, especially on burning efficiency, fuel consumption estimation and emission factors. It makes the best use of EFFISnear-real time and detailed information on forest fires, mainly concerning products with a high temporal resolution, which is needed to simulate smoke dispersion and chemical transformation in the atmosphere.A case study of a forest fire event in the north of Portugal on October 14, 2011, with a total of 4400ha of burnt area, was selected to test this forest fire emission model. The fine scale information used in this study included: (1) 3-hresolution meteorological fields; (2) daily evolution of the cumulative fire perimeter from the EFFIS rapid damage assessment system; and (3) a fine spatial resolution fuel map, forest type map and topography. The 3-hevolution of pollutant emissions was calculated for gas and particulate species based on the evolution of the burnt area increase and fuel consumption. The estimated forest fire emissions represent more than 90% of the total annual (anthropogenic and natural) emissions over the study region. The impact of these forest fire emissions was analyzed in terms of air quality, using observational data from the nearest air quality monitoring station. High peaks of NO2 and SO2 were registered simultaneously during the period 06-09a.m. and a later peak of PM from 07a.m. to 15p.m
Brachycoelium salamandrae (Frölich, 1789) (Digenea: Brachycoeliidae): ultrastructural study of spermiogenesis and the mature spermatozoon
No full textUltrastructural characters of spermiogenesis and the mature spermatozoon of Brachycoelium salamandrae are described by means of transmission electron microscopy. Spermiogenesis begins with the formation of a differentiation zone containing a nucleus, several mitochondria, and two centrioles associated with striated rootlets and with an intercentriolar body between them. The two centrioles originate two free flagella that grow orthogonally to the median cytoplasmic process before fusing with it. The final stage of spermiogenesis is characterized by a constriction of the ring of arched membranes and the liberation of the young spermatozoon. In this final stage a pear shaped electron-dense material appears at the level of centrioles. Spermatozoon of B. salamandrae exhibits two axonemes of different length with the 9+'1' trepaxonematan pattern, a nucleus, two mitochondria, two bundles of parallel cortical microtubules and granules of glycogen. Additionally, the spermatozoon of B. salamandrae shows external ornamentations of the plasma membrane and spinelike bodies. The most relevant spermatozoon characters of B. salamandrae are discussed and compared with those of other species belonging to the superfamily Gorgoderoidea
Changes in zooplankton communities along a mercury contamination gradient in a coastal lagoon (Ria de Aveiro, Portugal)
No full textThe main objective of this paper was to evaluate the impact of mercury on the zooplankton communities' structure and functioning and their bioaccumulation patterns along a contamination gradient in a temperate coastal lagoon. Our results demonstrated that total abundance was not negatively affected by Hg contamination, since the most contaminated areas presented the highest values, being the copepod Acartia tonsa the dominant species, which means that it is a very well adapted and tolerant species to mercury. Nevertheless, negative effects were observed in terms of species diversity, since the most contaminated areas presented the lowest values of species richness, evenness and heterogeneity. Moreover, the spatial mercury gradient was reflected on the bioaccumulation patterns of the zooplankton communities. This reinforces the idea that zooplankton can be considered as an important vehicle of mercury transfer through the food pelagic web since it constitutes a primordial food resource for several commercial fish species