Ferromagnetic order in aged Co-doped TiO2 anatase nanopowders

Oxide based diluted magnetic semiconductor (DMS) materials have been a subject of increasing interest due to reports of room temperature ferromagnetism in several systems and their potential use in the development of spintronic devices. However, concerns on the stability of the magnetic properties of different DMS systems have been raised. Their magnetic moment is often unstable, vanishing with a characteristic decay time of weeks or months, which precludes the development of real applications. This paper reports on the ferromagnetic properties of two-year-aged Ti1-xCoxO2-δ reduced anatase nanopowders with different Co contents (0.03≤x≤0.10). Aged samples retain rather high values of magnetization, remanence and coercivity which provide strong evidence for a quite preserved long-range ferromagnetic order. In what concern Co segregation, some degree of metastability of the diluted Co doped anatase structure could be inferred in the case of the sample with the higher Co content.

O efeito da drenagem linfática manual e das bandas neuromusculares na reabilitação pós-lipoaspiração para reconstrução mamária: estudo de caso

Introdução – A reconstrução mamária, no processo pós-cancro da mama, poderá ser levada a cabo através da lipoaspiração cujas consequências poderão ser ultrapassadas através da fisioterapia. Objetivo – Verificar, num estudo de caso, os resultados da drenagem linfática manual (DLM) e das bandas neuromusculares (BNM) na dor, edema, hematoma e pigmentação do abdómen e mamas após lipoaspiração para reconstrução mamária. Metodologia – Uma paciente foi sujeita a 10 sessões de fisioterapia com aplicação de DLM e BNM. Em cada sessão foram avaliados, nas mamas e no abdómen, a dor, o edema, o hematoma e a pigmentação. Resultados – Eliminação da dor, desaparecimento do hematoma abdominal, normalização da pigmentação mamária e diminuição do edema. Conclusão – Neste estudo de caso, a DLM e as BNM melhoram as consequências no pós-cirúrgico de lipoaspiração para reconstrução mamária. ABSTRACT - Introduction – Breast reconstruction, post breast cancer, can be carried out through liposuction which consequences may be overcomed through physiotherapy. Objective – Check, in a study case, the results of manual lymphatic drainage (MLD) and neuromuscular bandages (NMB) in pain, edema, bruising and pigmentation on abdomen and breasts, after liposuction for breast reconstruction. Methodology – A patient underwent 10 sessions of physiotherapy with application of MLD and NMB. In each session were evaluated breast and abdomen pain, edema, bruising and pigmentation. Results – Elimination of pain, disappearance of abdominal hematoma, normalization of breast pigmentation and reduction of edema. Conclusion – In this study case, MLD and NMB improve the consequences of post-surgical liposuction for breast reconstruction.

On the monoids of transformations that preserve the order and a uniform partition

In this article we consider the monoid O(mxn) of all order-preserving full transformations on a chain with mn elements that preserve a uniformm-partition and its submonoids O(mxn)(+) and O(mxn)(-) of all extensive transformations and of all co-extensive transformations, respectively. We determine their ranks and construct a bilateral semidirect product decomposition of O(mxn) in terms of O(mxn)(-) and O(mxn)(+).

Positive solutions of fourth order problems with clamped beam boundary conditions

n this paper we make an exhaustive study of the fourth order linear operator u((4)) + M u coupled with the clamped beam conditions u(0) = u(1) = u'(0) = u'(1) = 0. We obtain the exact values on the real parameter M for which this operator satisfies an anti-maximum principle. Such a property is equivalent to the fact that the related Green's function is nonnegative in [0, 1] x [0, 1]. When M < 0 we obtain the best estimate by means of the spectral theory and for M > 0 we attain the optimal value by studying the oscillation properties of the solutions of the homogeneous equation u((4)) + M u = 0. By using the method of lower and upper solutions we deduce the existence of solutions for nonlinear problems coupled with this boundary conditions. (C) 2011 Elsevier Ltd. All rights reserved.

Wind turbines equipped with fractional-order controllers: Stress on the mechanical drive train due to a converter control malfunction

This paper is on variable-speed wind turbines with permanent magnet synchronous generator (PMSG). Three different drive train mass models and three different topologies for the power-electronic converters are considered. The three different topologies considered are respectively a matrix, a two-level and a multilevel converter. A novel control strategy, based on fractional-order controllers, is proposed for the wind turbines. Simulation results are presented to illustrate the behaviour of the wind turbines during a converter control malfunction, considering the fractional-order controllers. Finally, conclusions are duly drawn. Copyright (C) 2010 John Wiley & Sons, Ltd.

Manual de manutenção preventiva de sistemas de elevação vertical para transporte de pessoas

Nos últimos anos, tem-se observado uma preocupação frequente com as questões estratégicas da manutenção, nomeadamente com o plano e modelo a adoptar, face aos constantes progressos que se têm verificado ao nível da incorporação de tecnologia nos equipamentos. A indústria de elevação tem-se dedicado em grande parte à realização de um serviço de manutenção baseado nas boas práticas adquiridas experimentalmente ao longo dos anos, de acordo com a legislação em vigor e com os seus objectivos operacionais de cada empresa. No entanto, existe a necessidade de estabelecer novas políticas de manutenção, que incorporem as mais recentes tendências, científicas e tecnológicas, que identifiquem os graus de criticidade de cada equipamento, de acordo com a sua fiabilidade e com a disponibilidade requerida pelos utilizadores e donos dos equipamentos, com o objectivo de aumentar o nível do serviço prestado e por consequência, a satisfação dos clientes. Tendo como caso de estudo uma empresa que exerce a sua actividade na área da elevação, este trabalho procura identificar os vários aspectos que careciam de melhoria no serviço de manutenção usualmente prestado, procurando dar especial importância ao planeamento, à programação e à metodologia a utilizar, por forma a tornar esse mesmo serviço mais eficiente e eficaz. Por outro lado, um serviço de manutenção, concretamente na área de elevação, pode e deve ser mais diferenciado, mais tangível, mais parametrizado, para que se possa avaliar e medir com mais assertividade a sua execução. São poucos, para não dizer que não existem, os estudos e trabalhos dedicados a este tema, pelo que o desafio deste trabalho foi precisamente esse, o de abordar um tema muito específico, mas de grande importância para o universo empresarial. Por essa razão, foram realizados vários inquéritos e entrevistas a pessoas que exercem a sua actividade profissional nesta área, tendo sido também realizadas auditorias a várias instalações e à forma como convencionalmente os técnicos de manutenção realizam as suas tarefas, com o objectivo de identificar os vários aspectos que careciam de melhoria. Com base nos resultados obtidos e nos conhecimentos adquiridos pelo autor na sua formação académica e ao longo da sua experiência profissional, definiram-se novas estratégias e orientações para a elaboração e implementação de um manual de manutenção, que possa ser seguido pelos técnicos que realizam diariamente o serviço de manutenção nas várias instalações que possuem espalhadas pelas suas rotas de manutenção.

Será que as empresas portuguesas seguem a pecking order na escolha das alternativas de financiamento?

Mestrado em Contabilidade e Análise Financeira

Synthesis of new Fe(II) and Ru(II) eta(5)-monocyclopentadienyl compounds showing significant second order NLO properties

A series of new ruthenium(II) complexes of the general formula [Ru(eta(5)-C5H5)(PP)(L)][PF6] (PP = DPPE or 2PPh(3), L = 4-butoxybenzonitrile or N-(3-cyanophenyl)formamide) and the binuclear iron(II) complex [Fe(eta(5)-C5H5)(PP)(mu-L)(PP)(eta(5)-C5H5)Fe][PF6](2) (L = (E)-2-(3-(4-nitrophenyl)allylidene)malononitrile, that has been also newly synthesized) have been prepared and studied to evaluate their potential in the second harmonic generation property. All the new compounds were fully characterized by NMR, IR and UV-Vis spectroscopies and their electrochemistry behaviour was studied by cyclic voltammetry. Quadratic hyperpolarizabilities (beta) of three of the complexes have been determined by hyper-Rayleigh scattering (HRS) measurements at fundamental wavelength of 1500 nm and the calculated static beta(0) values are found to fall in the range 65-212 x 10(-30) esu. Compound presenting beta(0) = 212 x 10(-30) esu has revealed to be 1.2 times more efficient than urea standard in the second harmonic generation (SHG) property, measured in the solid state by Kurtz powder technique, using a Nd:YAG laser (1064 nm). (C) 2013 Elsevier B.V. All rights reserved.

Contribuição para a caracterização da emissão de nanopartículas em processos de soldadura e avaliação de riscos decorrentes do processo

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica Ramo de processos químicos

10 kVp rule – An anthropomorphic pelvis phantom imaging study using a CR system: impact on image quality and effective dose using AEC and manual mode

Purpose - This study aims to investigate the influence of tube potential (kVp) variation in relation to perceptual image quality and effective dose (E) for pelvis using automatic exposure control (AEC) and non-AEC in a Computed Radiography (CR) system. Methods and materials - To determine the effects of using AEC and non-AEC by applying the 10 kVp rule in two experiments using an anthropomorphic pelvis phantom. Images were acquired using 10 kVp increments (60–120 kVp) for both experiments. The first experiment, based on seven AEC combinations, produced 49 images. The mean mAs from each kVp increment were used as a baseline for the second experiment producing 35 images. A total of 84 images were produced and a panel of 5 experienced observers participated for the image scoring using the two alternative forced choice (2AFC) visual grading software. PCXMC software was used to estimate E. Results - A decrease in perceptual image quality as the kVp increases was observed both in non-AEC and AEC experiments, however no significant statistical differences (p > 0.05) were found. Image quality scores from all observers at 10 kVp increments for all mAs values using non-AEC mode demonstrates a better score up to 90 kVp. E results show a statistically significant decrease (p = 0.000) on the 75th quartile from 0.37 mSv at 60 kVp to 0.13 mSv at 120 kVp when applying the 10 kVp rule in non-AEC mode. Conclusion - Using the 10 kVp rule, no significant reduction in perceptual image quality is observed when increasing kVp whilst a marked and significant E reduction is observed.

Biaxial Nematic Order in the Hard-boomerang Fluid

We consider a fluid of hard boomerangs, each composed of two hard spherocylinders joined at their ends at an angle Psi. The resulting particle is nonconvex and biaxial. The occurence of nematic order in such a system has been investigated using Straley's theory, which is a simplificaton of Onsager's second-virial treatment of long hard rods, and by bifurcation analysis. The excluded volume of two hard boomerangs has been approximated by the sum of excluded volumes of pairs of constituent spherocylinders, and the angle-dependent second-virial coefficient has been replaced by a low-order interpolating function. At the so-called Landau point, Psi(Landau)approximate to 107.4 degrees, the fluid undergoes a continuous transition from the isotropic to a biaxial nematic (B) phase. For Psi not equal Psi(Landau) ordering is via a first-order transition into a rod-like uniaxial nematic phase (N(+)) if Psi > Psi(Landau), or a plate-like uniaxial nematic (N(-)) phase if Psi < Psi(Landau). The B phase is separated from the N(+) and N(-) phases by two lines of continuous transitions meeting at the Landau point. This topology of the phase diagram is in agreement with previous studies of spheroplatelets and biaxial ellipsoids. We have checked the accuracy of our theory by performing numerical calculations of the angle-dependent second virial coefficient, which yields Psi(Landau)approximate to 110 degrees for very long rods, and Psi(Landau)approximate to 90 degrees for short rods. In the latter case, the I-N transitions occur at unphysically high packing fractions, reflecting the inappropriateness of the second-virial approximation in this limit.

Image quality and dose analysis for a PA chest X-ray: comparison between AEC mode acquisition and manual mode using the 10 kVp ‘rule’

Purpose - To compare the image quality and effective dose applying the 10 kVp rule with manual mode acquisition and AEC mode in PA chest X-ray. Method - 68 images (with and without lesions) were acquired using an anthropomorphic chest phantom using a Wolverson Arcoma X-ray unit. These images were compared against a reference image using the 2 alternative forced choice (2AFC) method. The effective dose (E) was calculated using PCXMC software using the exposure parameters and the DAP. The exposure index (lgM provided by Agfa systems) was recorded. Results - Exposure time decreases more when applying the 10 kVp rule with manual mode (50%–28%) when compared with automatic mode (36%–23%). Statistical differences for E between several ionization chambers' combinations for AEC mode were found (p = 0.002). E is lower when using only the right AEC ionization chamber. Considering the image quality there are no statistical differences (p = 0.348) between the different ionization chambers' combinations for AEC mode for images with no lesions. Considering lgM values, it was demonstrated that they were higher when the AEC mode was used compared to the manual mode. It was also observed that lgM values obtained with AEC mode increased as kVp value went up. The image quality scores did not demonstrate statistical significant differences (p = 0.343) for the images with lesions comparing manual with AEC mode. Conclusion - In general the E is lower when manual mode is used. By using the right AEC ionising chamber under the lung the E will be the lowest in comparison to other ionising chambers. The use of the 10 kVp rule did not affect the visibility of the lesions or image quality.

A class of singular first order differential equations with applications in reaction-diffusion

Agências Financiadoras: FCT e MIUR

A educação tecnológica como disciplina de opção de escola e os novos desafios do professor no ano de transição

Relatório de estágio apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino da Educação Visual e Tecnológica no Ensino Básico

Compreensão na leitura num manual de estudo do meio

A aquisição de competências ao nível da compreensão na leitura apresenta-se, cada vez mais, como o caminho para chegar ao conhecimento. O tipo de texto que se assume como o meio privilegiado de acesso ao conhecimento é o texto expositivo. Como tal, é importante que os textos a que os alunos têm acesso diariamente na sala de aula (nomeadamente, os textos dos manuais) sejam adequados ao desenvolvimento dessas competências. Neste estudo,analisaram-se os textos expositivos do manual de Estudo do Meio do 4.º ano mais adotado em Portugal no ano letivo 2010/2011. Em concreto, apurou-se a percentagem de textos expositivos existentes no manual, analisou-se a sua estrutura (Meyer, 1985), o tipo de questões que os acompanham, bem como as relações entre as perguntas e as respostas (Raphael, 1986, cit. em Giasson, 2000). O manual foi ainda analisado à luz do que é preconizado pelos documentos oficiais do Ministério da Educação.