Design and characterization of zeolite membranes for fluid separation

Experimental and theoretical methods have been used to study zeolite structures, properties and applications as membranes for separation purposes. Thin layers of silicalite-1 and Na-LTA zeolites have been synthesised onto carbon-graphite supports using a hydrothermal synthesis procedure. The separation behaviour of the composite membranes was characterized by gas permeation studies of pure, binary and ternary mixtures of methane, ethane and propane. The influence of temperature and feed gas mixture composition on the separation and selectivity performance of the membranes was also investigated. It was found that the silicalite-1 composite membranes synthesised onto the 4 hour oxidized carbon-graphite supports showed the most promising separation behaviour of all the composite membranes investigated. Molecular simulation methods were used to gain an understanding of how hydrocarbon molecules behave both within the pores and on the surfaces of silicalite-1, mordenite and LTA zeolites. Molecular dynamic simulations were used to investigate the influence of temperature and molecular loadings on the diffusional behaviour of hydrocarbons in zeolites. Both hydroxylated (surface termination with hydroxyl groups) and non-hydroxylated silicalite-1 and Na-mordenite surfaces were generated. For both zeolites the most stable surfaces correspond to the {010} surface. For the silicalite-1 {010} surface the adsorption of hydrocarbons and molecular water onto the hydroxylated surface showed a favourable exothermic adsorption process compared to adsorption on the non-hydroxylated surface. With the Na-mordenite {010} surface the adsorption of hydrocarbons onto both the hydroxylated and non-hydroxylated surfaces had a combination of favourable and non-favourable adsorption energies, while the adsorption of molecular water onto both types of surface was found to be a favourable adsorption process.

The separation of hydrogen and carbon monoxide using polymer membranes

This work studies the development of polymer membranes for the separation of hydrogen and carbon monoxide from a syngas produced by the partial oxidation of natural gas. The CO product is then used for the large scale manufacture of acetic acid by reaction with methanol. A method of economic evaluation has been developed for the process as a whole and a comparison is made between separation of the H2/CO mixture by a membrane system and the conventional method of cryogenic distillation. Costs are based on bids obtained from suppliers for several different specifications for the purity of the CO fed to the acetic acid reactor. When the purity of the CO is set at that obtained by cryogenic distillation it is shown that the membrane separator offers only a marginal cost advantage. Cost parameters for the membrane separation systems have been defined in terms of effective selectivity and cost permeability. These new parameters, obtained from an analysis of the bids, are then used in a procedure which defines the optimum degree of separation and recovery of carbon monoxide for a minimum cost of manufacture of acetic acid. It is shown that a significant cost reduction is achieved with a membrane separator at the optimum process conditions. A method of "targeting" the properties of new membranes has been developed. This involves defining the properties for new (hypothetical -yet to be developed) membranes such that their use for the hydrogen/carbon monoxide separation will produce a reduced cost of acetic acid manufacture. The use of the targeting method is illustrated in the development of new membranes for the separation of hydrogen and carbon monoxide. The selection of polymeric materials for new membranes is based on molecular design methods which predict the polymer properties from the molecular groups making up the polymer molecule. Two approaches have been used. One method develops the analogy between gas solubility in liquids and that in polymers. The UNIFAC group contribution method is then used to predict gas solubility in liquids. In the second method the polymer Permachor number, developed by Salame, has been correlated with hydrogen and carbon monoxide permeabilities. These correlations are used to predict the permeabilities of gases through polymers. Materials have been tested for hydrogen and carbon monoxide permeabilities and improvements in expected economic performance have been achieved.

Occurrence and transformation of organomercury in the Florida Everglades

In this study, a new method was developed based on aqueous phenylation, purge-and-trap preconcentration, gas chromatography (GC) separation, and detection by atomic fluorescence spectrometry (AFS) or inductively coupled plasma mass spectrometry (ICPMS). This technique is suitable for simultaneous determination of trace or ultratrace levels of CH3Hg+ and CH3CH2Hg+ in environmental samples. Method detection limits were 0.03 ng/L for both CH3Hg+ and CH3CH2Hg+ when AFS was used as the detector and 0.02 and 0.01 ng/L for CH3Hg+ and CH 3CH2Hg+ with ICPMS, respectively. The new method has the additional benefits of being free from interference by Cl - and dissolved organic matter. Using the method developed, both CH3Hg+ and CH3CH2Hg+ were detected in a number of soil and sediment samples collected from the Florida Everglades. The identity of CH3CH2Hg+ was verified by purge-and-trap-GC/MS analysis. The possibility of analytical artifact was excluded by using stable isotope tracer technique in combination with ICPMS detection. CH3CH 2Hg+ in the soil samples analyzed was at ng/g level, similar to that of CH3Hg+. The prevalence of CH 3CH2Hg+ in the soil of the Florida Everglades suggests that ethylation plays an important role in the geochemistry of Hg in this wetland. Soil incubation and sawgrass culture experiments using stable isotope tracers revealed that CH3Hg+ was mainly produced by microbial activities under anaerobic conditions, agreeing well with the general understanding of methylation mechanisms of Hg in the environment. Ethylation of Hg was not confirmed in these experiments, indicating that ethylation of Hg most probably follows different mechanisms in comparison to methylation. Further experiments revealed that trace levels of ethyllead species were able to transfer ethyl group to Hg in both deionized water and freshwater matrixes, producing CH3CH2Hg+. This might partially account for the occurrence of CH3CH2Hg+ in the relatively pristine environment of the Florida Everglades.

Color-based surface reflectance separation for scene illumination estimation and rendering

Given the importance of color processing in computer vision and computer graphics, estimating and rendering illumination spectral reflectance of image scenes is important to advance the capability of a large class of applications such as scene reconstruction, rendering, surface segmentation, object recognition, and reflectance estimation. Consequently, this dissertation proposes effective methods for reflection components separation and rendering in single scene images. Based on the dichromatic reflectance model, a novel decomposition technique, named the Mean-Shift Decomposition (MSD) method, is introduced to separate the specular from diffuse reflectance components. This technique provides a direct access to surface shape information through diffuse shading pixel isolation. More importantly, this process does not require any local color segmentation process, which differs from the traditional methods that operate by aggregating color information along each image plane. ^ Exploiting the merits of the MSD method, a scene illumination rendering technique is designed to estimate the relative contributing specular reflectance attributes of a scene image. The image feature subset targeted provides a direct access to the surface illumination information, while a newly introduced efficient rendering method reshapes the dynamic range distribution of the specular reflectance components over each image color channel. This image enhancement technique renders the scene illumination reflection effectively without altering the scene’s surface diffuse attributes contributing to realistic rendering effects. ^ As an ancillary contribution, an effective color constancy algorithm based on the dichromatic reflectance model was also developed. This algorithm selects image highlights in order to extract the prominent surface reflectance that reproduces the exact illumination chromaticity. This evaluation is presented using a novel voting scheme technique based on histogram analysis. ^ In each of the three main contributions, empirical evaluations were performed on synthetic and real-world image scenes taken from three different color image datasets. The experimental results show over 90% accuracy in illumination estimation contributing to near real world illumination rendering effects. ^

Status of Early 19th-Century Names Authored in Parallel by Wied and Schinz for South American Reptiles and Amphibians, with Designations of Three Nomina Protecta

Prince Maximilian zu Wied's great exploration of coastal Brazil in 1815-1817 resulted in important collections of reptiles, amphibians, birds, and mammals, many of which were new species later described by Wied himself The bulk of his collection was purchased for the American Museum of Natural History in 1869, although many ""type specimens"" had disappeared earlier. Wied carefully identified his localities but did not designate type specimens or type localities, which are taxonomic concepts that were not yet established. Information and manuscript names on a fraction (17 species) of his Brazilian reptiles and amphibians were transmitted by Wied to Prof. Heinrich Rudolf Schinz at the University of Zurich. Schinz included these species (credited to their discoverer ""Princ. Max."") in the second volume of Das Thierreich ... (1822). Most are junior objective synonyms of names published by Wied. However, six of the 17 names used by Schinz predate Wied's own publications. Three were manuscript names never published by Wied because he determined the species to be previously known. (1) Lacerta vittata Schinz, 1822 (a nomen oblitum) = Lacerta striata sensu Wied (a misidentification, non Linnaeus nec sensu Merrem) = Kentropyx calcarata Spix, 1825, herein qualified as a nomen protectum. (2) Polychrus virescens Schinz, 1822 = Lacerta marmorata Linnaeus, 1758 (now Polychrus marmoratus). (3) Scincus cyanurus Schinz, 1822 (a nomen oblitum) = Gymnophthalmus quadrilineatus sensu Wied (a misidentification, non Linnaeus nec sensu Merrem) = Micrablepharus maximiliani (Reinhardt and Lutken, ""1861"" [1862]), herein qualified as a nomen protectum. Qualifying Scincus cyanurus Schinz, 1822, as a nomen oblitum also removes the problem of homonymy with the later-named Pacific skink Scincus cyanurus Lesson (= Emoia cyanura). The remaining three names used by Schinz are senior objective synonyms that take priority over Wied's names. (4) Bufo cinctus Schinz, 1822, is senior to Bufo cinctus Wied, 1823; both, however, are junior synonyms of Bufo crucifer Wied, 1821 = Chaunus crucifer (Wied). (5) Agama picta Schinz, 1822, is senior to Agama picta Wied, 1823, requiring a change of authorship for this poorly known species, to be known as Enyalius pictus (Schinz). (6) Lacerta cyanomelas Schinz, 1822, predates Teius cyanomelas Wied, 1824 (1822-1831) both nomina oblita. Wied's illustration and description shows cyanomelas as apparently conspecific with the recently described but already well-known Cnemidophorus nativo Rocha et al., 1997, which is the valid name because of its qualification herein as a nomen protectum. The preceding specific name cyanomelas (as corrected in an errata section) is misspelled several ways in different copies of Schinz's original description (""cyanom las,"" ""cyanomlas,"" and cyanom""). Loosening, separation, and final loss of the last three letters of movable type in the printing chase probably accounts for the variant misspellings.

Rapid and sensitive measurements of nitrate ester explosives using microchip electrophoresis with electrochemical detection

This article describes an effective microchip protocol based on electrophoretic-separation and electrochemical detection for highly sensitive and rapid measurements of nitrate ester explosives, including ethylene glycol dinitrate (EGDN), pentaerythritol tetranitrate (PETN), propylene glycol dinitrate (PGDN) and glyceryl trinitrate (nitroglycerin, NG). Factors influencing the separation and detection processes were examined and optimized. Under the optimal separation conditions obtained using a 15 mM borate buffer (pH 9.2) containing 20 mM SDS, and applying a separation voltage of 1500 V, the four nitrate ester explosives were separated within less than 3 min. The glassy-carbon amperometric detector (operated at -0.9 V vs. Ag/AgCl) offers convenient cathodic detection down to the picogram level, with detection limits of 0.5 ppm and 0.3 ppm for PGDN and for NG, respectively, along with good repeatability (RSD of 1.8-2.3%; n = 6) and linearity (over the 10-60 ppm range). Such effective microchip operation offers great promise for field screening of nitrate ester explosives and for supporting various counter-terrorism surveillance activities.

Isolation and analysis of bioactive isoflavonoids and chalcone from a new type of Brazilian propolis

Activity-directed fractionation and purification processes were employed to identify isoflavonoids with antioxidant and antimicrobial activities from Brazilian red propolis. Crude propolis was extracted with ethanol (80%. v/v) and fractioned by liquid-liquid extraction technique using hexane and chloroform. Since chloroform fraction showed strong antioxidant and antimicrobial activities it was purified and isolated using various chromatographic techniques. Comparing our spectral data (UV, NMR, and mass spectrometry) with values found in the literature, we identified two bioactive isoflavonoids (vestitol and neovestitol), together with one chalcone (isoliquiritigenin). Vestitol presented higher antioxidant activity against beta-carotene consumption than neovestitol. The antimicrobial activity of these three compounds against Staphylococcus aureus, Streptococcus mutans, and Actinomyces naeslundii was evaluated and we concluded that isoliquiritigenin was the most active one with lower MIC, ranging from 15.6 to 62.5 mu g/mL. Our results showed that Brazilian red propolis has biologically active isoflavonoids that may be used as a mild antioxidant and antimicrobial for food preservation. (C) 2010 Elsevier B.V. All rights reserved.

Rapid Determination of Water-Soluble and Fat-Soluble Vitamins in Commercial Formulations by MEEKC

Microemulsion electrokinetic capillary chromatography has been successfully applied to the separation and determination of water-soluble vitamins (thiamine hydrochloride, riboflavin, niacin, pyridoxine hydrochloride, folic acid, cobalamin, ascorbic acid) and a fat-soluble vitamin (alpha-tocopherol acetate). The optimal microemulsion buffer contained sodium dodecylsulfate (SDS) as surfactant, butan-1-ol as the co-surfactant, ethyl acetate as the oil and pH 9.2 tetraborate buffer, modified with 15% (v/v) 2-propanol. UV detection at 214 nm gave adequate sensitivity without interference from sample excipients. Under the optimized conditions, the vitamins were baseline separated in less than 7 min. Analytical curves of peak area versus concentration presented coefficients of determination (R (2) ) > 0.99, acceptable limits of quantification between 8.40 and 16.23 mu g mL(-1) were obtained. Vitamin levels in liquid formulation were quantified with intra-day precision better than 0.99% RSD for migration time and 1.19% RSD for peak area ratio. Recoveries ranged between 98.7 and 101.7%. The method was considered appropriate for rapid and routine analysis.

Language, discourse and politics

After discussing the meaning of the word politics, this paper shows that there are four possible approaches to the issue of the relationships between language, discourse and politics: a) the intrinsic political nature of language; b) the relations of power between discourses and their political dimension; c) the relations of power between languages and the political dimension of their usage and; d) linguistic policies. This paper addresses only the first two of these items. Languages have an intrinsically political nature because they subject their speakers to their order. The acts of silencing operationalized in discourse manifest a relation of power. The spread of discourses in the social space is also subject to the order of power. The use of language may be the space of pertinence, but is also that of exclusion, separation and even the elimination of the other. Therefore, language is not a neutral communication tool, but it is permeated by politics, by power. Because of the dislocations that it produces, literature is a form of swindling language, unveiling the powers that are imprinted on it.

On the structure, electrochemistry, and spectroscopy of the (N,N'-bis(2'-(dimethylamino)ethyl)-N,N'-dimethylpropane-1,3-diamine)copper(II) ion

The synthesis, spectroscopy, and electrochemistry of the acyclic tertiary tetraamine copper(II) complex [CuL(1)](ClO4)(2) (L(1) = N,N-bis(2'-(dimethylamino)ethyl)-N,N'-dimethylpropane-1,3-diamine) is reported. The X-ray crystal structure of [CuL(1)(OClO3)(2)] reveals a tetragonally elongated CuN4O2 coordination sphere, exhibiting relatively long Cu-N bond lengths for a Cu-II tetraamine, and a small tetrahedral distortion of the CuN4 plane. The [CuL(1)](2+) ion displays a single, reversible, one-electron reduction at -0.06 V vs Ag/AgCl. The results presented herein illustrate the inherent difficulties associated with the separation and characterization of Cu-II complexes of tertiary tetraamines, and some previously incorrect assertions and unexplained observations of other workers are discussed.

Self-assembly in chains, rings, and branches: a single component system with two critical points

Agências financiadoras: FCT - PEstOE/FIS/UI0618/2011; PTDC/FIS/098254/2008 ERC-PATCHYCOLLOIDS e MIUR-PRIN

Compact SMB chromatography for binary separation

A thesis submitted for the degree of Doctor of Philosophy

Fractionation of hydro-ethanolic extracts from grape pomace through membrane processing: the effect of membrane and extracting media on process performance

The EM3E Master is an Education Programme supported by the European Commission, the European Membrane Society (EMS), the European Membrane House (EMH), and a large international network of industrial companies, research centers and universities

Res Publica: Citizenship and Political Representation in Portugal, 1820-1926

The term res publica (literally “thing of the people”) was coined by the Romans to translate the Greek word politeia, which, as we know, referred to a political community organised in accordance with certain principles, amongst which the notion of the “good life” (as against exclusively private interests) was paramount. This ideal also came to be known as political virtue. To achieve it, it was necessary to combine the best of each “constitutional” type and avoid their worst aspects (tyranny, oligarchy and ochlocracy). Hence, the term acquired from the Greeks a sense of being a “mixed” and “balanced” system. Anyone that was entitled to citizenship could participate in the governance of the “public thing”. This implied the institutionalization of open debate and confrontation between interested parties as a way of achieving the consensus necessary to ensure that man the political animal, who fought with words and reason, prevailed over his “natural” counterpart. These premises lie at the heart of the project which is now being presented under the title of Res Publica: Citizenship and Political Representation in Portugal, 1820-1926. The fact that it is integrated into the centenary commemorations of the establishment of the Republic in Portugal is significant, as it was the idea of revolution – with its promise of rupture and change – that inspired it. However, it has also sought to explore events that could be considered the precursor of democratization in the history of Portugal, namely the vintista, setembrista and patuleia revolutions. It is true that the republican regime was opposed to the monarchic. However, although the thesis that monarchy would inevitably lead to tyranny had held sway for centuries, it had also been long believed that the monarchic system could be as “politically virtuous” as a republic (in the strict sense of the word) provided that power was not concentrated in the hands of a single individual. Moreover, various historical experiments had shown that republics could also degenerate into Caesarism and different kinds of despotism. Thus, when absolutism began to be overturned in continental Europe in the name of the natural rights of man and the new social pact theories, initiating the difficult process of (written) constitutionalization, the monarchic principle began to be qualified as a “monarchy hedged by republican institutions”, a situation in which not even the king was exempt from isonomy. This context justifies the time frame chosen here, as it captures the various changes and continuities that run through it. Having rejected the imperative mandate and the reinstatement of the model of corporative representation (which did not mean that, in new contexts, this might not be revived, or that the second chamber established by the Constitutional Charter of 1826 might not be given another lease of life), a new power base was convened: national sovereignty, a precept that would be shared by the monarchic constitutions of 1822 and 1838, and by the republican one of 1911. This followed the French example (manifested in the monarchic constitution of 1791 and in the Spanish constitution of 1812), as not even republicans entertained a tradition of republicanism based upon popular sovereignty. This enables us to better understand the rejection of direct democracy and universal suffrage, and also the long incapacitation (concerning voting and standing for office) of the vast body of “passive” citizens, justified by “enlightened”, property- and gender-based criteria. Although the republicans had promised in the propaganda phase to alter this situation, they ultimately failed to do so. Indeed, throughout the whole period under analysis, the realisation of the potential of national sovereignty was mediated above all by the individual citizen through his choice of representatives. However, this representation was indirect and took place at national level, in the hope that action would be motivated not by particular local interests but by the common good, as dictated by reason. This was considered the only way for the law to be virtuous, a requirement that was also manifested in the separation and balance of powers. As sovereignty was postulated as single and indivisible, so would be the nation that gave it soul and the State that embodied it. Although these characteristics were common to foreign paradigms of reference, in Portugal, the constitutionalization process also sought to nationalise the idea of Empire. Indeed, this had been the overriding purpose of the 1822 Constitution, and it persisted, even after the loss of Brazil, until decolonization. Then, the dream of a single nation stretching from the Minho to Timor finally came to an end.

Women’s perception of separation/divorce in Portugal: A sociodemographic profile

This article focuses on the personal experiences of Portuguese women regarding separation and divorce. The sample included 96 women, with at least 1 child, who responded to an inventory that addressed conflict, dysfunctional conjugality, emotional experiences, social support, and adaptation to divorce. Higher levels of conflict and marital dysfunction in litigious divorces were found, as well as more conflict when different lawyers were employed. Those women who were satisfied with alimony and visiting rights reported less conflict, fewer negative emotional experiences, and greater social support. Level of education and duration of separation influenced women’s perceptions. Implications for intervention are addressed.