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

Acta Crystallographica F64 (2008) 636-638

PINPIN a-Si: H based structures for X-ray image detection using the laser scanning technique

Conventional film based X-ray imaging systems are being replaced by their digital equivalents. Different approaches are being followed by considering direct or indirect conversion, with the later technique dominating. The typical, indirect conversion, X-ray panel detector uses a phosphor for X-ray conversion coupled to a large area array of amorphous silicon based optical sensors and a couple of switching thin film transistors (TFT). The pixel information can then be readout by switching the correspondent line and column transistors, routing the signal to an external amplifier. In this work we follow an alternative approach, where the electrical switching performed by the TFT is replaced by optical scanning using a low power laser beam and a sensing/switching PINPIN structure, thus resulting in a simpler device. The optically active device is a PINPIN array, sharing both front and back electrical contacts, deposited over a glass substrate. During X-ray exposure, each sensing side photodiode collects photons generated by the scintillator screen (560 nm), charging its internal capacitance. Subsequently a laser beam (445 nm) scans the switching diodes (back side) retrieving the stored charge in a sequential way, reconstructing the image. In this paper we present recent work on the optoelectronic characterization of the PINPIN structure to be incorporated in the X-ray image sensor. The results from the optoelectronic characterization of the device and the dependence on scanning beam parameters are presented and discussed. Preliminary results of line scans are also presented. (C) 2014 Elsevier B.V. All rights reserved.

Efeito de flutuações de composição química nas transformações dos aços: aplicação a um aço-ferramenta DIN X 38 CrMoV 51

Dissertação apresentada para obtenção do grau de Doutor em Ciência dos Materiais, especialidade de Metalurgia, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

Métrica vertebral-automático: desenvolvimento e construção de um sistema de posicionamento X/Z, com motores passo a passo

Dissertação apresentada no Departamento de Física na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Biomédica

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

X-Ray Spectrom. 2003; 32: 396–401

Caracterização das qualidades de radiação de uma ampola de raios X com ânodo de tungsténio no âmbito da mamografia

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Biomédica

Caracterização do feixe de radiação X num bloco operatório em cirurgia ortop

RESUMO - Na radiologia de intervenção, e concretamente em ortopedia, os raios X são intensamente utilizados permitindo a visualização de diversas técnicas de intervenção cirúrgica. Do ponto de vista médico as vantagens dessa prática são enormes, contudo, os profissionais de saúde envolvidos são susceptíveis de estarem expostos a valores de dose de radiação que significam a sua classificação como trabalhadores expostos. O presente estudo realizou-se num hospital e teve como objectivo obter uma estimativa das doses envolvidas em ortopedia de intervenção, utilizando várias metodologias experimentais para caracterização do campo de radiação primário e secundário. Observaram-se distintos níveis de dose de acordo com a zona anatómica exposta à radiação X: (i) gónadas — 0,02 a 3 mGy/h; (ii) cristalino — 0,06 a 1 mGy/h e (iii) mãos — 0,6 mGy/h. Tais resultados evidenciam uma clara necessidade de utilização de equipamentos de protecção e de vigilância dosimétrica pelos profissionais de saúde envolvidos no acto cirúrgico.--------------------------ABSTRACT - In intervention radiology, and more specifically in orthopaedics, X-rays are intensely used allowing the visualization of many acts of clinical intervention. From a clinical perspective, the advantages of that practice are significant; however, involved health care professionals are susceptible of being exposed to radiation dose values that mean their classification as exposed workers. The present study, performed in a hospital, aimed to obtain an estimation of the doses involved in intervention orthopaedics through several experimental methodologies in order to characterise the primary and the secondary radiation fields. Different levels of dose were observed according to the anatomic area exposed to X radiation: (i) gonads — 0.02 a 3 mGy/h; (ii) crystalline lens — 0.06 a 1 mGy/h e (iii) hands – 0.6 mGy/h. Such results denote a clear need of protection equipment use and of dosimetric surveillance by the health

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

On the analysis of data emerging in non-linear and complex systemscomparison of two X-Ray prony spectra

New arguments proving that successive (repeated) measurements have a memory and actually remember each other are presented. The recognition of this peculiarity can change essentially the existing paradigm associated with conventional observation in behavior of different complex systems and lead towards the application of an intermediate model (IM). This IM can provide a very accurate fit of the measured data in terms of the Prony's decomposition. This decomposition, in turn, contains a small set of the fitting parameters relatively to the number of initial data points and allows comparing the measured data in cases where the “best fit” model based on some specific physical principles is absent. As an example, we consider two X-ray diffractometers (defined in paper as A- (“cheap”) and B- (“expensive”) that are used after their proper calibration for the measuring of the same substance (corundum a-Al2O3). The amplitude-frequency response (AFR) obtained in the frame of the Prony's decomposition can be used for comparison of the spectra recorded from (A) and (B) - X-ray diffractometers (XRDs) for calibration and other practical purposes. We prove also that the Fourier decomposition can be adapted to “ideal” experiment without memory while the Prony's decomposition corresponds to real measurement and can be fitted in the frame of the IM in this case. New statistical parameters describing the properties of experimental equipment (irrespective to their internal “filling”) are found. The suggested approach is rather general and can be used for calibration and comparison of different complex dynamical systems in practical purposes.