Influence of the sodium/proton replacement on the structural, morphological and photocatalytic properties of titanate nanotubes

Titanate nanotubes (TNT) with different sodium contents have been synthesised using a hydrothermal approach and a swift and highly controllable post-washing processes. The influence of the sodium/proton replacement on the structural and morphological characteristics of the prepared materials was analysed. Different optical behaviour was observed depending on the Na+/H+ samples' content. A band gap energy of 3.27\pm0.03 eV was estimated for the material with higher sodium content while a value of 2.81\pm0.02 eV was inferred for the most protonated material, which therefore exhibits an absorption edge in the near visible region. The point of zero charge of the materials was determined and the influence of the sodium content on the adsorption of both cationic and anionic organic dyes was studied. The photocatalytic performance of the TNT samples was evaluated in the rhodamine 6G degradation process. Best photodegradation results were obtained when using the most protonated material as catalyst, although this material has shown the lowest R6G adsorption capability.Comment: 22 pages, 8 figures, accepted for publication in Journal of Photochemistry and Photobiology A: Chemistr

Geochemistry of groundwater from Graciosa Island (Azores): A contribution to the hydrothermal system conceptual model

Graciosa island is located in the Azores Archipelago, along the so-called Terceira Rift, a major tectonic structure that makes the NE boundary of the Azores Plateau. In general terms, it includes a basaltic plataform on the NW and a silicic poligenetic volcano with caldera on the SE, the Graciosa Caldera Volcano. This volcano has produced significant tephra falls, pyroclastic flows, lahars, and lava flows, both of basaltic s.l. and trachitic s.l. composition. The hydrothermal system shows fumarolic emissions inside the volcano caldera and thermal springs located along the shoreline. This system is exploitated in a thermal building through shallow and deep (110 m) boreholes, near the coast. In Graciosa two types of Na-Cl groundwater systems can be identified: 1) a cold one emerging at springs and exploited by wells for public water supply, and 2) a hydrothermal system with temperatures around 40-44 °C. The cold groundwaters have pH higher than 7 and different degree of mineralization, according to the proximity to the sea. The thermal waters show mixing with seawater, pH varying between 6.20 and 6.94, 166 mg/L of SiO2, and significant concentration of metals, such as Mn, Fe, Co, Ni, Cu and Zn. The thermal water mineralization varies strongly, showing EC from 8.87 mS/cm (shallow water) to 47.4 mS/cm (deeper water). The higher mineralized water is rich in CO2(g), with 2130 mg/L of total dissolved CO2. Geothermometers application reveals aquifer temperature around 167 °C and immature/mixed waters, not reaching complete equilibrium with reservoir rock. The geochemistry of the thermal waters indicates the occurrence of seawater/host rock interaction processes at high temperature and slightly acid conditions, favored by CO2(g) input, and a different degrees of mixing with cold and shallow groundwaters

Solubilization and hydrolysis of porcine coagulated blood protein using sub-critical solvent extraction

Pork represents a major fraction of the meat consumed worldwide but only 30% of the blood generated in slaughterhouses is re-used as raw material for food and feed. Innovative technologies and efficient processing strategies capable of generating added-value products from it are now attracting attention. In this study, the hydrolysis of porcine coagulated blood using sub-critical solvent extraction was investigated. Biomass was hydrolyzed using different temperatures (120–210 °C), applying only water (sub-critical water; SCW) or water with a low concentration of alkali (0.1 mol L−1 NaOH) and different reaction times (30–90 min). Resultant hydrolysates were analyzed for crude and soluble protein, peptide profile, and bioactivity by combining protein quantification, antioxidant activity, and fast protein liquid chromatography measurements. Results showed that increasing temperature increases the degree of hydrolysis and that the addition of NaOH enhances the solubilization of peptides with high molecular weights. Also, hydrolysates showed interesting antioxidant activity, being 60 min the time of reaction with best antioxidant activity. Nevertheless, using only water (SCW) as solvent, without chemical additives, allows the delivering of interesting protein-based bioactive fractions. Sub-critical solvent treatment of porcine blood resulted in added-value fractions with potential bioactivities through a simple and environmentally friendly process.info:eu-repo/semantics/publishedVersio

Multiplet Effects in the Quasiparticle Band Structure of the f1−f2f^1-f^2 Anderson Model

In this paper, we examine the mean field electronic structure of the $f^1-f^2$ Anderson lattice model in a slave boson approximation, which should be useful in understanding the physics of correlated metals with more than one f electron per site such as uranium-based heavy fermion superconductors. We find that the multiplet structure of the $f^2$ ion acts to quench the crystal field splitting in the quasiparticle electronic structure. This is consistent with experimental observations in such metals as $UPt_3$.Comment: 9 pages, revtex, 3 uuencoded postscript figures attached at en

O movimento de mulheres piauienses para obter sua formação profissional como enfermeiras 1959-1973

O estudo objetivou descrever a luta de mulheres piauienses por sua formação como enfermeiras em outros estados do Brasil. Tratase de uma pesquisa histórico- social produzida a partir de fontes orais e secundárias. Os dados foram analisados à luz dos conceitos de espaço social, campo, capital, poder simbólico, luta e violência simbólica de Pierre Bourdieu. Os resultados apontam as lutas simbólicas no processo de formação profissional dessas piauienses, em sua maioria, em universidades na região nordeste. Ao realizarem o curso de enfermagem fora do Estado, essas jovens tiveram um conjunto de conhecimentos incorporados, que aliados à diversidade de culturas favoreceram o ganho de capital científico e cultural. Conclui-se que as lutas desenvolvidas por essas mulheres resultaram em ganhos simbólicos e sociais, além da incorporação do habitus profissional. O estudo contribuirá para a história da enfermagem, na construção de novos registros, além de abrir portas para a realização de novas pesquisas sobre a temática.El estudio tuvo como objetivo describir la lucha de las mujeres Piauí para su formación como enfermeras en otros estados de Brasil. Se trata de una investigación histórico-social producida a partir de fuentes orales y secundarias. Los datos se analizaron de acuerdo a los conceptos de espacio social, campo, el capital, el poder simbólico, la lucha y la violencia simbólica de Pierre Bourdieu. Los resultados muestran las luchas simbólicas en el proceso de formación de éstos mujeres piauienses, en su mayoría en las universidades en el noreste. En la realización del programa de enfermería fuera del estado, estos jóvenes tenían un conjunto de conocimientos incorporados, lo que combinado con la diversidad de culturas favoreció el capital científico y cultural de ganancia. En conclusión, las luchas que estas mujeres resultaron en ganancias simbólicas y sociales así como la incorporación de habitus profesional. El estudio contribuirá a la historia de la enfermería en la construcción de nuevos registros, y abrir las puertas a nuevas investigaciones sobre el tema.The study aimed to describe the struggle of Piauí women for their training as nurses in other Brazilian states. It is a social-historical research produced from oral and secondary sources. Data were analyzed according to the concepts of social space, field, capital, symbolic power, struggle and symbolic violence of Pierre Bourdieu. The results show the symbolic struggles in the training process of these women do Piauí, mostly at universities in the Northeast. When conducting the nursing course outside the state, these young people had a set of embedded knowledge, which combined with the diversity of cultures promoted the gain scientific and cultural capital. In conclusion, the fights undertaken by these women resulted in symbolic and social gains as well the incorporation of professional habitus. The study will contribute to the history of nursing in the construction of new records, and open doors to new research on the subject

Synthesis of titanate nanofibers co-sensitized with ZnS and Bi2S3 nanocrystallites and their application on pollutants removal

The synthesis of nanocomposite materials combining titanate nanofibers (TNF) with nanocrystalline ZnS and Bi2S3 semiconductors is described in this work. The TNF were produced via hydrothermal synthesis and sensitized with the semiconductor nanoparticles, through a single-source precursor decomposition method. ZnS and Bi2S3 nanoparticles were successfully grown onto the TNF's surface and Bi2S3-ZnS/TNF nanocomposite materials with different layouts were obtained using either a layer-by-layer or a co-sensitization approach. The samples' photocatalytic performance was first evaluated through the production of the hydroxyl radical using terephthalic acid as probe molecule. All the tested samples show photocatalytic ability for the production of this oxidizing species. Afterwards, the samples were investigated for the removal of methylene blue. The nanocomposite materials with best adsorption ability for the organic dye were the ZnS/TNF and Bi2S3ZnS/TNF. The removal of the methylene blue was systematically studied, and the most promising results were obtained considering a sequential combination of an adsorption-photocatalytic degradation process using the Bi2S3ZnS/TNF powder as a highly adsorbent and photocatalyst material.Comment: 26 pages, 10 figure

Influência da qualidade dos materiais de reprodução na reflorestação com sobreiro

O sobreiro ocupa em Portugal cerca de 721000 ha o que corresponde a 21,5 % da área fl orestal nacional e 33% da área mundial (APCOR, 2005). A sua distribuição no território nacional traduz não só a sua adaptação a determinadas condições edafo-climaticas, mas tem sido condicionada por várias circunstancias, como o arroteamento, o fogo, o abuso do pastoreio, a exploração agrícola intensiva e as plantações fl orestais que contrariaram ou favoreceram a sua existência nesses locais (Natividade, 1950). A distribuição desta espécie é particularmente signifi cativa em zonas onde têm ocorrido acontecimentos climáticos graves e onde os níveis de desertifi cação humana são críticos. A fi leira da cortiça salienta-se por Portugal ocupar o primeiro lugar entre os países produtores, transformadores e exportadores de cortiça, correspondendo-lhe mais de metade da produção mundial desta matéria-prima. O nosso País é a origem de aproximadamente 60% das transacções de cortiça a nível mundial, valor que sobe para 80% quando nos referimos a transacções de produtos transformados. A nível nacional, o valor das exportações de cortiça representam aproximadamente 0,7% do PIB, 2,24% das exportações e correspondem a mais de 33% do conjunto das exportações de produtos fl orestais (APCOR, 2005). Para além da importância económica do sector corticeiro a nível nacional, o aumento da consciência e do interesse da sociedade nas questões ambientais, faz com que o montado de sobro seja reconhecido cada vez mais como um espaço fl orestal, de elevada biodiversidade, paisagísticamente único, que potencia micro-economias locais baseadas numa agricultura e pastorícia extensivas, interessante para outras actividades como o turismo rural e a caça. O sobreiro tem sido a espécie fl orestal que mais tem benefi ciado dos meios fi nanceiros disponibilizados aos proprietários fl orestais para a refl orestação no âmbito da aplicação das medidas de reforma da Política Agrícola Comum da UE, na arborização das terras agrícolas. Contudo, têm-se registado com frequência elevadas taxas de insucesso na arborização sendo a qualidade dos materiais florestais de reprodução (MFR) apontada como uma das causas. Neste trabalho abordaremos a a qualidade dos materiais de reprodução, considerando-a do ponto de vista genético e fisiológicoN/

Conceptual model of the Quenturas hydromineral resource (Furnas volcano, S. Miguel Island): a contribution

RESUMO: O Vulcão das Furnas, na ilha de São Miguel, comporta no seu interior uma grande variabilidade de nascentes, que se podem classificar em 5 tipos distintos, nomeadamente frias lisas, frias gasocarbónicas, termais ácidas, termais básicas e condensado de fumarola, de características marcadas e variadas, originando a designada “Hidrópole” das Furnas. A Concessão Hidromineral das Furnas comporta parte importante destas nascentes, entre elas o Recurso Hidromineral das Quenturas, ou Água Férrea das Quenturas, referida como “3”. Trata-se de uma água termal ácida, com 59 °C de temperatura, pH ácido e mineralização elevada, cuja origem se considera corresponder ao aquecimento de aquíferos mais superficiais por vapor hidrotermal que ascende do aquífero hidrotermal profundo, conferindo a estas águas temperatura e uma importante componente gasocarbónica. Dados isotópicos apontam uma altitude de recarga de cerca de 800 m para esta nascente e uma idade compreendida entre os 23 e os 30 anos.ABSTRACT: Furnas Volcano, located on S. Miguel Island, is home to a large variety of springs, that can be classified in 5 different groups, namely cold waters, cold CO2-rich waters, thermal waters with low pH, thermal waters with high pH and fumaroles, each with distinctive characteristics, originating the “Furnas Hydropolis”. The Furnas Hidromineral Permit includes some of these springs, including the Quenturas spring, also known as Água Férrea das Quenturas, which is referred in the permit by the number “3”. Quenturas is a thermal water with low pH, with a temperature of 59 °C and high mineralization. It has its origin in the shallower aquifers that are heated by the hydrothermal steam provided by the deep-seated hydrothermal aquifers, providing them with temperature and an important gaseous component. Isotopic data estimates a recharge altitude of approximately 800 m for this spring, and 23 to 30 years of age.info:eu-repo/semantics/publishedVersio

Castaing Instability and Precessing Domains in Confined Alkali Gases

We explore analogy between two-component quantum alkali gases and spin-polarized helium systems. Recent experiments in trapped gases are put into the frame of the existing theory for Castaing instability in transverse channel and formation of homogeneous precessing domains in spin-polarized systems. Analogous effects have already been observed in spin-polarized $$ and $^{3}He- ^{4}He$ mixtures systems. The threshold effect of the confining potential on the instability is analyzed. New experimental possibilities for observation of transverse instability in a trap are discussed.Comment: 6 RevTex pages, no figure