Lake Kumphawapi revisited – The complex climatic and environmental record of a tropical wetland in NE Thailand

Kumphawapi, which is Thailand’s largest natural freshwater lake, contains a >10,000-year-long climatic and environmental archive. New data sets (stratigraphy, chronology, hydrogen isotopes, plant macrofossil and charcoal records) for two sedimentary sequences are here combined with earlier multi-proxy studies to provide a comprehensive reconstruction of past climatic and environmental changes for Northeast Thailand. Gradually higher moisture availability due to a strengthening of the summer monsoon led to the formation of a large shallow lake in the Kumphawapi basin between >10,700 and c. 7000 cal. BP. The marked increase in moisture availability and lower evaporation between c. 7000 and 6400 cal. BP favoured the growth and expansion of vegetation in and around the shallow lake. The increase in biomass led to gradual overgrowing and infilling, to an apparent lake level lowering and to the development of a wetland. Multiple hiatuses are apparent in all investigated sequences between c. 6500 and 1400 cal. BP and are explained by periodic desiccation events of the wetland and erosion due to the subsequent lake level rise. The rise in lake level, which started c. 2000 cal. BP and reached shallower parts c. 1400 cal. BP, is attributed to an increase in effective moisture availability. The timing of hydroclimatic conditions during the past 2000 years cannot be resolved because of chronological limitations.

Biomass fly ash incorporation in cement based materials

In recent years, pressures on global environment and energy security have led to an increasing demand on renewable energy sources, and diversification of Europe’s energy supply. Among these resources the biomass could exert an important role, since it is considered a renewable and CO2 neutral energy resource once the consumption rate is lower than the growth rate, and can potentially provide energy for heat, power and transports from the same installation. Currently, most of the biomass ash produced in industrial plants is either disposed of in landfill or recycled on agricultural fields or forest, and most times this goes on without any form of control. However, considering that the disposal cost of biomass ashes are raising, and that biomass ash volumes are increasing worldwide, a sustainable ash management has to be established. The main objective of the present study is the effect of biomass fly ashes in cement mortars and concretes in order to be used as a supplementary cementitious material. The wastes analyzed in the study were collected from the fluidized bed boilers and grate boilers available in the thermal power plants and paper pulp plants situated in Portugal. The physical as well as chemical characterisations of the biomass fly ashes were investigated. The cement was replaced by the biomass fly ashes in 10, 20 and 30% (weight %) in order to investigate the fresh properties as well as the hardened properties of biomass fly ash incorporated cement mortar and concrete formulations. Expansion reactions such as alkali silica reaction (ASR), sulphate attack (external and internal) were conducted in order to check the durability of the biomass fly ash incorporated cement mortars and concretes. Alternative applications such as incorporation in lime mortars and alkali activation of the biomass fly ashes were also attempted. The biomass fly ash particles were irregular in shape and fine in nature. The chemical characterization revealed that the biomass fly ashes were similar to a class C fly ash. The mortar results showed a good scope for biomass fly ashes as supplementary cementitious materials in lower dosages (<20%). The poor workability, concerns about the organic content, alkalis, chlorides and sulphates stand as the reasons for preventing the use of biomass fly ash in high content in the cement mortars. The results obtained from the durability tests have shown a clear reduction in expansion for the biomass fly ash mortars/concretes and the binder blend made with biomass fly ash (20%) and metakaolin (10%) inhibited the ASR reaction effectively. The biomass fly ash incorporation in lime mortars did not improve the mortar properties significantly though the carbonation was enhanced in the 15-20% incorporation. The biomass fly ash metakaolin blend worked well in the alkali activated complex binder application also. Portland cement free binders (with 30-40 MPa compressive strength) were obtained on the alkali activation of biomass fly ashes (60-80%) blended with metakaolin (20-40%).

Revestimentos compatíveis para alvenarias antigas sujeitas a ação severa da água

Uma das maiores causas de degradação dos revestimentos é a presença de sais solúveis, tanto nas zonas costeiras como nas zonas continentais. Estes sais podem ter origens distintas, tais como: humidade ascensional, nevoeiro salino, inundações ou ainda estarem presentes nos próprios materiais, como é o caso da utilização de areias mal lavadas. O local onde os sais cristalizam é dependente do tipo de transporte entre a alvenaria e o revestimento, assim como da severidade da envolvente ambiental (temperatura e humidade relativa). Com esta tese pretende-se desenvolver revestimentos de substituição compatíveis, eficazes e duráveis para alvenarias antigas sujeitas à ação severa da água (humidade ascensional através das fundações com elevada concentração de NaCl); desenvolver ensaios de envelhecimento acelerado baseados em ciclos de dissolução e cristalização que permitam simular a ação severa da água; perceber a influência de revestimentos com caraterísticas extremas de permeabilidade ao vapor de água aplicados nas duas faces do mesmo suporte (argamassas de cimento e resina versus argamassas de cal), e sujeitos à ação severa da água; perceber a influência de vários fatores, tais como : rasgos verticais contínuos executados no emboço e a utilização de hidrófugo no reboco no desempenho dos vários sistemas de revestimento desenvolvidos, quando sujeitos à ação severa da água;; utilizar a remoção eletrocinética de sais, em provetes simulando a influência da alvenaria e dos revestimentos, com o objetivo de reduzir a sua concentração de NaCl, para que no futuro possa ser aplicado de forma eficaz em paredes de edifícios antigos, enquanto ação de manutenção, e desta forma aumentar a durabilidade dos revestimentos. Para atingir os objetivos descritos, foram considerados: i) o desenvolvimento de provetes que permitam considerar os sistemas de revestimento desenvolvidos nesta tese e o suporte, e que simulem uma alvenaria revestida em ambas as faces, e com os quais seja possível a simulação da ação severa da água em laboratório e, ii) o desenvolvimento ciclos de dissolução e cristalização numa parede de grandes dimensões existente em laboratório, que permitam simular a ação severa da água em condições tão reais quanto possível. O objetivo final deste estudo é o desenvolvimento de um revestimento de substituição denominado “emboço ventilado” para paredes de edifícios antigos com revestimentos degradados devido à presença de humidade ascensional e sais solúveis. Pretende-se que este sistema de revestimento, composto por duas camadas de revestimento (camada base e reboco), seja compatível, durável e eficaz, e que funcione como um sistema de acumulação no qual os sais cristalizem na camada base do sistema de revestimento (executada com rasgos verticais) e não na alvenaria ou na camada exterior.

A ilha de Moçambique durante a Idade Moderna

Dissertação de Mestrado, História da Arte Portuguesa, Faculdade de Ciências Humanans e Sociais, Universidade do Algarve, 2007

Análise e caracterização da expressão e papel funcional dos potenciais genes da família 2 GPCRs no protostómio Caenorhabditis elegans

Dissertação de Mestrado, Biotecnologia, Faculdade de Engenharia de Recursos Naturais, Universidade do Algarve, 2009

Calibração e validação do modelo espectral de previsão da agitação marítima SWAN em zonas costeiras

Dissertação mest., Oceanografia, Universidade do Algarve, 2009

A vision system for detecting paths and moving obstacles for the blind

In this paper we present a monocular vision system for a navigation aid. The system assists blind persons in following paths and sidewalks, and it alerts the user to moving obstacles which may be on collision course. Path borders and the vanishing point are de-tected by edges and an adapted Hough transform. Opti-cal flow is detected by using a hierarchical, multi-scale tree structure with annotated keypoints. The tree struc-ture also allows to segregate moving objects, indicating where on the path the objects are. Moreover, the centre of the object relative to the vanishing point indicates whether an object is approaching or not.

Variabilidade do "upwelling" costeiro durante o holocénico nas margens atlânticas ocidental e meridional da Península Ibérica

Tese de dout., Ciências do Mar, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2005

Bio-synthesis of nanosized semiconductors using mine wastes as material sources

This work describes the synthesis of nanosized metal sulfides and respective SiO2 and/or TiO2 composites in high yield via a straightforward process, under ambient conditions (temperature and pressure), by adding to aqueous metals a nutrient solution containing biologically generated sulfide from sulfate-reducing bacteria (SRB). The nanoparticles‘ (NPs) morphological properties were shown not to be markedly altered by the SRB growth media composition neither by the presence of bacterial cells. We further extended the work carried out, using the effluent of a bioremediation system previously established. The process results in the synthesis of added value products obtained from metal rich effluents, such as Acid Mine Drainage (AMD), when associated with the bioremediation process. Precipitation of metals using sulfide allows for the possibility of selective recovery, as different metal sulfides possess different solubilities. We have evaluated the selective precipitation of CuS, ZnS and FeS as nanosized metal sulfides. Again, we have also tested the precipitation of these metal sulfides in the presence of support structures, such as SiO2. Studies were carried out using both artificial and real solutions in a continuous bioremediation system. We found that this method allowed for a highly selective precipitation of copper and a lower selectivity in the precipitation of zinc and iron, though all metals were efficiently removed (>93% removal). This research has also demonstrated the potential of ZnS-TiO2 nanocomposites as catalysts in the photodegradation of organic pollutants using the cationic dye, Safranin-T, as a model contaminant. The influence of the catalyst amount, initial pH and dye concentration were also evaluated. Finally, the efficiency of the precipitates as catalysts in sunlight mediated photodegradation was investigated, using different volumes of dye-contaminated water (150 mL and 10 L). This work demonstrates that all tested composites have the potential to be used as photocatalysts for the degradation of Safranin-T.

Ecologic zonation model of the benthic foraminifera and thecamoebians of Guadiana river estuary and application in paleoenvironmental reconstruction

Tese de doutoramento, Ciências do Mar ( Processos de Ecossistemas Marinhos), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2012

Diatom-based characterization of iberian coastal environments at different time scales

Tese de doutoramento, Geologia (Geologia Económica e do Ambiente), Universidade de Lisboa, Faculdade de Ciências, 2014

New tools for chemical modification of proteins

Tese de doutoramento, Farmácia (Química Farmacêutica e Terapêutica), Universidade de Lisboa, Faculdade de Farmácia, 2014

Caracterização de ambientes de transição do SW Alentejano a distintas escalas temporais

Tese de doutoramento, Geologia (Geologia Económica e do Ambiente), Universidade de Lisboa, Faculdade de Ciências, 2016

Intervention Recommendations to Minimize the 30-Day Risk-of-Readmission for Heart Failure

Thesis (Master's)--University of Washington, 2015

Parties in democratic national assemblies: comparative assessment of parliaments note

This paper argues that the analysis of democratic national assemblies is not only impossible without discussing political parties, but also incomprehensible without recognizing parties as the most significant organizations within them. Parties have structured political groupings and demands on government even before assemblies were democratically elected. And although parties may be in decline as institutions mediating between society and government in the current era, they remain significant as organizing forces within government. The paper first explains the origins of party organizations within parliaments by exploring why individual members and the assemblies taken as a whole need parties: what are their costs and benefits? It then describes the manner in which party organizations operate in different national assembly chambers. The third section analyses types and sources of party influence, including the role played by party leaders in manipulating legislative agendas, structuring Members’ policy choices and shaping policy outcomes. The final section reviews how politi- cal scientists have sought to explain intra-party cohesion and discipline across different national assemblies.