Pathway Weathering in Granitoid Rocks from Central Region of Angola: Geochemical and Mineralogical Data

The Central Region of Angola is characterized by the abundance of granitoid rocks, whose weathering “in situ” originated the so-called residual soils. The textural, geochemical and mineralogical properties of these soils depend not only on the chemical composition of parent rock, but mainly on the local climatic and geomorphological characteristics. In the study area, sampling sites were selected, which extend from the region of Kwanza- Norte (Kassenda, Dondo) through Kwanza-Sul (Cangulo, Quibala and Waco Kungo) until the plateau of Huambo, where samples of fresh rock, weathered rock and its residual soil were collected along each weathering profile. Chemical analytical data were determined using X-ray fluorescence (XRF) analysis of the major and minor elements, whereas mineralogical data were determined using X-ray diffraction (XRD), on the samples of rock and on the respective residual soil. The results obtained and their comparative analysis between the sampling sites, as well as along each weathering profile is presented. This paper allows contributing to the knowledge of the geochemical weathering in tropical areas, as is the case of Angola

Diferenças na intensidade de alteração química de sedimentos Pliocénicos a norte e sul do Mondego

Procede-se a uma análise comparativa de características mineralógicas e geoquímicas (elementos maiores), usadas na definição de intensidade de altyeração química, de sedimentos pliocénicos colhidos na margem Atlântica a norte e sul do rio Mondego. Ainda que se note alguma influência da granulometria dos sedimentos nas características composicionais, as unidades a norte do Mondego revelam sempre alteração química menos intensa que as unidades a sul do Mondego. Estas diferenças justificam-se por proveniência distinta e não devem ter qualquer significado climático

On-line characterization of single bubbles in multiphase reactors

ECCE 7 - 7th European Congress of Chemical Engineering, CHISA 2010 - 19th International Congress of Chemical and Process Engineering (CD-ROM of Full Texts)This paper presents an on-line method to identify automatically the single bubbles (isolated bubbles without influence of surrounded bubbles) in multiphase reactors. Based on image analysis technique (IA), the method combines the information given by IA with the Discriminant factorial analysis leading to results that allow the identification of single bubbles and the study of bubble population complexity. By this way, it is possible to characterize the single bubbles on different conditions and to understand their influence on mass transfer. Agreement between automated and manual classification, measured in terms of a performance index, is 90% on average. Further, it describes the application of such methodology to the study of the influence of bubble characteristics (size, shape, bubble population complexity, etc) on the individual parameters of volumetric liquid side mass transfer coefficient, kLa. The experiments were done at different temperatures (25-35ºC) and superficial gas velocities (up to 14 mm/s) in a bubble column.info:eu-repo/semantics/publishedVersio

Biosurfactant-mediated biodegradation of straight and methyl-branched alkanes by Pseudomonas aeruginosa ATCC 55925

Accidental oil spills and waste disposal are important sources for environmental pollution. We investigated the biodegradation of alkanes by Pseudomonas aeruginosa ATCC 55925 in relation to a rhamnolipid surfactant produced by the same bacterial strain. Results showed that the linear C11-C21 compounds in a heating oil sample degraded from 6% to 100%, whereas the iso-alkanes tended to be recalcitrant unless they were exposed to the biosurfactant; under such condition total biodegradation was achieved. Only the biodegradation of the commercial C12-C19 alkanes could be demonstrated, ranging from 23% to 100%, depending on the experimental conditions. Pristane (a C19 branched alkane) only biodegraded when present alone with the biosurfactant and when included in an artificial mixture even without the biosurfactant. In all cases the biosurfactant significantly enhanced biodegradation. The electron scanning microscopy showed that cells depicted several adaptations to growth on hydrocarbons, such as biopolymeric spheres with embedded cells distributed over different layers on the spherical surfaces and cells linked to each other by extracellular appendages. Electron transmission microscopy revealed transparent inclusions, which were associated with hydrocarbon based-culture cells. These patterns of hydrocarbon biodegradation and cell adaptations depended on the substrate bioavailability, type and length of hydrocarbon

Cancro do colo do útero: que rastreio?

O cancro do colo do útero é um dos cancros evitáveis mais frequente nas mulheres, Ferlay (2004) e Parkin(2005). O padrão epidemiológico da doença, caracterizado por um período longo entre a detecção das primeiras lesões e a instalação da doença, favorece a sua inclusão em programas de rastreio organizado, por serem custo-eficientes e terem ganhos de saúde associados, ver Anttila (2004), Castellsague (2006) e Koutsky (1998). O presente estudo teve como objectivo auxiliar os elementos da Comissão de Rastreio do Cancro do Colo do Útero na Região Norte na tomada de decisões relativas aos aspectos mais controversos dos rastreios ao cancro do colo do útero: limite de idade das mulheres rastreadas, intervalo entre exames e método utilizado. Assim, construiu-se um modelo matemático, com o intuito de simular os impactos económicos e de saúde, das combinações das várias alternativas de rastreio. Por fim, foi feita uma análise custo-benefício das soluções encontradas e determinou-se a solução, i.e. a opção de rastreio, mais vantajosa.Cervical cancer is one of the most frequent avoidable cancers in women, Ferlay (2004) and Parkin(2005). The natural history of the disease, characterized for a long period between the detection of the rst injuries and invasive cancer, favours its inclusion in organized screening programs, since they are cost-e ective and have clear advantages for the health of the population, see Anttila (2004), Castellsague (2006) and Koutsky (1998). The aim of this study is to construct a mathematical model that can help the elements of the Commission delegated for planning the screening program, to decide about the most controversial aspects: target population, interval between examinations and method to be used. The mathematical model allows to simulate the economical and health impact of all the possible solutions. Finally, a cost-bene t analysis of the combined screening alternatives was done to determine the solution, i.e, the more advantageous screening program

Continuous-flow precipitation of hydroxyapatite at 37 °C in a meso oscillatory flow reactor

Continuous-flow precipitation of hydroxyapatite (HAp) was investigated in a meso oscillatory flow reactor (meso- OFR) and in a scaled-up meso-OFR, obtained by associating in series eight vertical meso-ORFs. Experiments were carried out under near-physiological conditions of temperature and pH, using fixed frequency ( f = 0.83 Hz) and amplitude (x0 = 4.5 mm), and varying the residence time from 0.4 to 6.7 min. It has been shown that the mean particle size and the aggregation degree of the prepared HAp particles decrease with decreasing residence time. HAp nanoparticles with a mean size (d50) of 77 nm, narrow size distribution, and uniform morphology were obtained at the lowest residence times, τ = 0.4 and 3.3 min in the meso-OFR and the scaled-up meso-OFR, respectively. These results show the capability of the meso-OFR and the scaled-up meso-OFR for continuous production of uniform HAp nanoparticles, while also confirming the possibility of OFR scale-up by in series association of individual OFRs

Process intensification of gas-liquid flows with a novel constricted oscillatory-meso tube

GLD-8 - 8th International Conference on Gas-Liquid and Gas-Liquid-Solid Reactor EngineeringA novel constricted meso-tube (4.4. mm internal diameter) operated with oscillatory flow mixing has recently demonstrated enhanced volumetric mass transfer coefficients ( kLa) for continuous gas-liquid flows. Values of kLa up to 0.16 s-1 were obtained with a very low air-inflow rate (QG = 0.28 ml min-1) for the continuous running of a liquid phase (QL = 1.58 ml min-1), while in the presence of fluid oscillations. This is a one-order of magnitude improvement in the O2 transfer efficiencies in comparison with those values typically found for the most common-aerated reactors (e.g. stirred tank reactor, bubbles column, air-lift reactor). The design of novel multiphase, scaled-down reactors based on this novel tube’s geometry allows the intensification of gas-liquid flow processes through reducing the required processing volumes and the improved performance in terms of mixing, residence times and mass transfer. As a correct design does require a full understanding of the mass transfer processes, the different contributions of the mass transfer coefficient and the gas-liquid interfacial area in the global kLa enhancement were explored and herein reportedinfo:eu-repo/semantics/publishedVersio

Enhancement of oxygen mass transfer in pneumatical bioreactors using n-dodecane as oxygen-vector

In biotechnology, oxygen mass transfer is a key parameter involved in the design and operation of bioreactors and it can be analyzed by means of the oxygen mass transfer coefficient (kLa). Due to the fact that oxygen has a very low solubility in an aqueous media (8–10 ppm at 20°C), actively growing cells can consume all the dissolved oxygen very fast, therefore, it has to be supplied continuously into the broths. In conventionally aerated bioreactors, low oxygen solubility combined with slow oxygen transfer rates often results in reduced growth and culture productivity. Due to their higher oxygen solubility, non-toxicity to microbes, antifoaming action, oxygen-vectors addition is one of the most effective methods to improve oxygen mass transfer rate in aerobic fermentations. The aim of this study was to investigate the use of n-dodecane as oxygen-vector in bubble column and air-lift bioreactors, under different working conditions (air superficial velocity, volumetric fraction of the organic phase, medium temperature). The results show that volumetric fraction of oxygen-vector (φ) has a great influence on kLa; in the presence of low volumetric fraction (φ=0.005 (v/v)), the oxygen mass transfer coefficient’s value in bubble column bioreactor was increased by almost 100% at 35°C and for φ=0.02 (v/v) by 5% at 25°C, while in air-lift bioreactor, at 25°C and φ=0.005 (v/v), the kLa value was enhanced by approximately 50%.his paper was supported by the project PERFORM-ERA "Postdoctoral Performance for Integration in the European Research Area" (ID-57649), financed by the European Social Fund and the Romanian Government

Development and characterization of cotton elastic yarns to improve wear comfort of bi-elastic thin fabrics

Clothing is our second skin, beyond the aesthetic function it primarily has the protective function. One cannot speak about clothing design without mentioning comfort and we may even say that they are not dissociable. The clothing design, in conceptual sense, cannot be successful if it does not take into account the comfort component. Among the many comfort dimensions, the sensorial and ergonomic dimensions of comfort which influence the sensory perception and the ability of a garment to "well fit", are largely determined by the elastic properties of the yarns and fabrics. The present work, relates to the development of cotton elastic yarns for bi-stretch woven fabrics, designed for high-quality women's fine shirting. The yarns were manufactured by the conventional core-spinning method, using different filaments in the core and cotton fibres as sheath. The physical-mechanical properties of the yarns were evaluated to assess their performance ability to improve bi-stretch fabrics wear comfort.FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136

Bioaccessibility by perspiration uptake of minerals from two diferent sulfurous peloids

The risks associated with the use of peloids in thermal centers, spas, or at home, must be tested to develop appropriate safety guidelines for peloids formulations and the release of substances of high concern. Additionally, the beneficial effects of some elements on human health should be assessed to aid in interpreting the therapeutic action and effectiveness of pelotherapy on dermatological or osteomuscular disorders. Therefore, a methodology was developed to better understand the biogeochemical behavior of the elements in formulated peloids. Two peloids were formulated with the same clay and two different sulfurous mineral-medicinal waters for 90 days, with light stirring every 15 days. Bentonite clay, with a high content of smectite and Ca and Mg as the main exchangeable cations, and high heat capacity, was used. The selected mineral-medicinal waters were collected from two Portuguese thermal centers with recognized therapeutic efficacy for rheumatic, respiratory and dermatological pathologies. The peloids were used without drying and withdrawn directly from the maturation tank, and a mixture of bentonite and demineralized water was prepared as a reference sample. A stabilized, ready-to-use, artificial perspiration test was used to simulate the peloids' interaction with skin. Thirty-one elements extracted from the two prepared peloids were analyzed using ICP-MS. The data were analyzed and related to the mineralogical composition of the original clay and supernatant composition of the maturation tanks. The content of some potentially toxic elements and metals' bioaccessibility by perspiration showed very low solubility and undetectable amounts extracted from the studied samples. This analytical method provided reliable information on dermal exposure and the identification of some elements that may enter the systemic circulation, requiring implementation of surveillance and control measures.Open access funding provided by FCT|FCCN (b-on). This research was funded by FCT—Fundação para a Ciência e a Tecnologia and Exatronic, Lda, Grant Number SFRH/BDE/11062/2015 and also supported by GeoBioTec Research Centre (UIDB/04035/2020), funded by FCT, FEDER funds through the Operational Program Competitiveness Factors COMPETE