In-situ X-ray diffraction studies during growth of Ni-Ti shape memory alloy films and their complementary ex-situ characterization

Shape Memory Alloy (SMA) Ni-Ti films have attracted much interest as functional and smart materials due to their unique properties. However, there are still important issues unresolved like formation of film texture and its control as well as substrate effects. Thus, the main challenge is not only the control of the microstructure, including stoichiometry and precipitates, but also the identification and control of the preferential orientation since it is a crucial factor in determining the shape memory behaviour. The aim of this PhD thesis is to study the optimisation of the deposition conditions of films of Ni-Ti in order to obtain the material fully crystallized at the end of the deposition, and to establish a clear relationship between the substrates and texture development. In order to achieve this objective, a two-magnetron sputter deposition chamber has been used allowing to heat and to apply a bias voltage to the substrate. It can be mounted into the six-circle diffractometer of the Rossendorf Beamline (ROBL) at the European Synchrotron Radiation Facility (ESRF), Grenoble, France, enabling an in-situ characterization by X-ray diffraction(XRD) of the films during their growth and annealing. The in-situ studies enable us to identify the different steps of the structural evolution during deposition with a set of parameters as well as to evaluate the effect of changing parameters on the structural characteristics of the deposited film. Besides the in-situ studies, other complementary ex-situ characterization techniques such as XRD at a laboratory source, Rutherford backscattering spectroscopy(RBS), Auger electron spectroscopy (AES), cross-sectional transmission electron microscopy (X-TEM), scanning electron microscopy (SEM), and electrical resistivity (ER) measurements during temperature cycling have been used for a fine structural characterization. In this study, mainly naturally and thermally oxidized Si(100) substrates, TiN buffer layers with different thicknesses (i.e. the TiN topmost layer crystallographic orientation is thickness dependent) and MgO(100) single crystals were used as substrates. The chosen experimental procedure led to a controlled composition and preferential orientation of the films. The type of substrate plays an important role for the texture of the sputtered Ni-Ti films and according to the ER results, the distinct crystallographic orientations of the Ni-Ti films influence their phase transformation characteristics.

Overproduction, crystallization and preliminary X-ray characterization of Abn2, an endo-1,5-alpha-arabinanase from Bacillus subtilis.

Acta Crystallographica F64 (2008) 636-638

Energy-dispersive x-ray fluorescence analysis of modern coloured glasses from Marinha Grande (Portugal)

X-Ray Spectrom. 2003; 32: 396–401

O controlo da tuberculose em Portugal : uma apreciação crítica epidemiológica gl

RESUMO - Com tanto ruído informativo e peças de informação incompletas e descontextualizadas, relativos ao controlo da tuberculose em Portugal, a chegarem ao cidadão e aos profissionais de saúde, não é fácil que eles disponham do conhecimento necessário ao desempenho dos respectivos papéis nesse controlo. O presente artigo pretende contribuir para um ganho real em conhecimento quanto (1) ao progresso no controlo da tuberculose em Portugal, enquadrado na evolução desse controlo noutras regiões pertinentes, e (2) aos aspectos do conhecimento disponível e da intervenção na população portuguesa que suscitem especial atenção, para melhoria no futuro imediato. Tem como estratégia integrar, e elevar ao nível de conhecimento, a informação disponibilizada nas fontes mais credíveis e pertinentes, valorizada no contexto da validade das mesmas fontes e da coerência dos diversos componentes. Relata o resultado de um exercício independente de apreciação crítica, com uma perspectiva epidemiológica. São observados: a situação actual, sobretudo a relativa aos anos de 2006 e 2007, e o desempenho do Programa Nacional de Controlo da Tuberculose (PNT), ambos relativizados à evolução recente e ao panorama internacional. O exercício de observação e revisão independentes baseia-se numa selecção de informação oficial e segue o mesmo método de abordagem que a O.M.S. faz nos seus relatórios anuais, à semelhança de outros exercícios já antes realizados. O controlo da tuberculose tem prosseguido a sua tímida, mas firme, evolução favorável, aproximando-se do nível já conseguido nos países seus vizinhos da Europa Ocidental. Em 2007, Portugal contribuiu para os 9 milhões de casos novos anuais, estimados no mundo, com 2916 casos notificados. A este número corresponde a taxa de incidência notificada de 25,7 por 100 000 habitantes e uma redução de 14% em relação ao ano anterior. Esta evolução afigura-se animadora, ainda que seja desejável um impacte mais acentuado do PNT, conforme é de esperar considerando o grau de desenvolvimento do País. A taxa de detecção de casos novos estimada é elevada e continua uma das melhores da Europa Ocidental — o que desfavorece artificialmente a imagem notificada do País, relativamente aos países com pior capacidade de detecção. A taxa de sucesso terapêutico melhorou de novo, situando- -se acima da meta de 85% preconizada pela O.M.S, para um bom controlo da tuberculose. Uma das consequências importantes é que se consegue um melhor aproveitamento da detecção habitualmente alcançada. O conhecimento no seu conjunto aponta para que o grau de controlo possa e deva realmente ser melhorado, sendo imperiosa a discriminação positiva das áreas geográficas e dos grupos populacionais em que tende a concentrar-se a emergência de maior número de casos e de resistências aos medicamentos. Deverão assim ser reforçados selectivamente tanto os meios de detecção e de intervenção clínica, como a qualidade da organização local da intervenção, para o cumprimento efectivo da estratégia DOTS. Enquanto programa vertical que atravessa os diversos níveis do sistema de cuidados de saúde, o desempenho do PNT sofre os efeitos das atribulações desses serviços, sobretudo os de cuidados primários, funcionando como uma «situação-marcadora» quanto ao desempenho do sistema de saúde. A evidência é de que é nesta primeira linha de cuidados que se decide o sucesso na detecção e no tratamento dos casos de tuberculose, reflectindo-se também aí o grau de desenvolvimento social e os comportamentos das populações, por sua vez determinantes do risco de doença e do sucesso terapêutico. ------------------- ABSTRACT - It is not easy that both the citizen and health professionals get enabled with the required knowledge, in order do play the corresponding roles in the control of tuberculosis, considering all the information noise and incomplete, out of context information pieces about the subject, that reach them. This paper is envisaging to contribute for a real gain in knowledge, regarding: (1) the progress in tuberculosis control in Portugal, framed by the evolution of such control in other pertinent regions and (2) the available knowledge and intervention aspects in the Portuguese population that require a special attention, for improvement. The article’s strategy is to integrate, and raise to a knowledge level, information provided by the most accredited and pertinent sources, interpreted as a function of the validity context of the same sources and of the coherence of the several components. Two aspects are observed: the current situation, in particular concerning years 2006 and 2007, and the performance of the National Programme for the Tuberculosis Control (PNT), both made relative to the recent evolution and to the international panorama. This independent observation and revision exercise is based on a selection of official information and follows the same approach that the World Health Organization (W.H.O.) uses in its annual reports, like other similar exercises previously undertaken. The control of tuberculosis is evolving in a shy, but firm, fashion, getting closer to the level already attained by the neighbor countries, in Western Europe. Portugal has contributed with 2916 new notified cases, to the 9 million annual cases estimated in the world, in 2007. This number corresponds to an incidence rate, for notified cases, of 25.7 per 100000 population, and to a reduction of 14% in one year. Such evolution seems encouraging, although a greater impact of PNT is desirable, as expected in relation to the degree of the Country development. Estimated new cases detection rate is high and keeps being one of the best in Western Europe — and this artificially disadvantages the notified image of the Country, as compared with other countries having a worst detection capacity. Treatment success rate has improved again and it is above the 85% target proposed by W.H.O., so that a good control of the disease is achieved. One of the important consequences is a better use of the attained detection. Altogether, knowledge suggests that the degree of control can and must be in fact better; and that a positive discrimination of geographic areas and population groups, in which a greater number of new cases and drug resistances tend to concentrate, is mandatory. Therefore, either clinical detection and intervention resources, or the quality of the local intervention organization have to be reinforced, if a total fulfillment of DOTS strategy is to be obtained. As a vertical programme that crosses the several levels of the health care system, PNT performance suffers the effects of services tribulations, mainly primary care, thus acting as a «markersituation » as to this system performance. Evidence shows that it is in this first line of care that success in both detection and treatment of tuberculosis cases is decided; and that this level also reveals the degree of social developmen

Cobalt-, zinc- and iron-bound forms of adenylate kinase (AK) from the sulfate-reducing bacterium Desulfovibrio gigas: purification, crystallization and preliminary X-ray diffraction analysis

Acta Crystallogr Sect F Struct Biol Cryst Commun. 2009 Sep 1;65(Pt 9):926-9

Purification, crystallization and preliminary X-ray diffraction analysis of adenosine triphosphate sulfurylase (ATPS) from the sulfate-reducing bacterium Desulfovibrio desulfuricans ATCC 27774

Acta Crystallogr Sect F Struct Biol Cryst Commun. 2008 Jul 1;64(Pt 7):593-5

Heterodimeric nitrate reductase (NapAB) from Cupriavidus necator H16: purification, crystallization and preliminary X-ray analysis

Acta Cryst. (2007). F63, 516–519

Ligand K-edge X-ray absorption spectroscopy and DFT calculations on [Fe3S4]0,+ clusters: delocalization, redox, and effect of the protein environment

Ligand K-edge XAS of an [Fe3S4]0 model complex is reported. The pre-edge can be resolved into contributions from the í2Ssulfide, í3Ssulfide, and Sthiolate ligands. The average ligand-metal bond covalencies obtained from these pre-edges are further distributed between Fe3+ and Fe2.5+ components using DFT calculations. The bridging ligand covalency in the [Fe2S2]+ subsite of the [Fe3S4]0 cluster is found to be significantly lower than its value in a reduced [Fe2S2] cluster (38% vs 61%, respectively). This lowered bridging ligand covalency reduces the superexchange coupling parameter J relative to its value in a reduced [Fe2S2]+ site (-146 cm-1 vs -360 cm-1, respectively). This decrease in J, along with estimates of the double exchange parameter B and vibronic coupling parameter ì2/k-, leads to an S ) 2 delocalized ground state in the [Fe3S4]0 cluster. The S K-edge XAS of the protein ferredoxin II (Fd II) from the D. gigas active site shows a decrease in covalency compared to the model complex, in the same oxidation state, which correlates with the number of H-bonding interactions to specific sulfur ligands present in the active site. The changes in ligand-metal bond covalencies upon redox compared with DFT calculations indicate that the redox reaction involves a two-electron change (one-electron ionization plus a spin change of a second electron) with significant electronic relaxation. The presence of the redox inactive Fe3+ center is found to decrease the barrier of the redox process in the [Fe3S4] cluster due to its strong antiferromagnetic coupling with the redox active Fe2S2 subsite.

Correlating EPR and X-ray structural analysis of arsenite-inhibited forms of aldehyde oxidoreductase

J Biol Inorg Chem (2007) 12:353–366 DOI 10.1007/s00775-006-0191-9

X-ray crystal structure and EPR spectra of "arsenite-inhibited" Desulfovibriogigas aldehyde dehydrogenase: a member of the xanthine oxidase family

J. Am. Chem. Soc., 2004, 126 (28), pp 8614–8615 DOI: 10.1021/ja0490222

Integrated study by NMR and X-ray Crystallography on the analysis of the molecular interactions in heme-binding proteins

Dissertação para obtenção do Grau de Doutor em Bioquímica, Especialidade Bioquímica Estrutural

Molecular determinants of ligand specificity in carbohydrate-binding modules: an NMR and X-ray crystallography integrated study

Dissertação para obtenção do Grau de Doutor em Bioquímica – Ramo Bioquímica Estrutural

Electron impact ionization cross sections and analysis of X-ray spectra

A thesis submitted for the degree of Ph. D. in Physics