Browsing by Author "Pereira, M."
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- Avaliação dos fatores de risco psicossociais e da perceção das condições do local de trabalho em lares de idososPublication . Pereira, M.; Gonçalves, P.; Rodrigues, S.; Andrade, GraçaDiversos estudos comprovam a capacidade dos fatores de risco psicossociais no local de trabalho afetarem a saúde física, mental e social dos trabalhadores. Face a esta problemática, este estudo tem como objetivo identificar os fatores de risco a que os profissionais que exerçam a sua atividade em lares de idosos estão expostos, bem como averiguar uma possível relação entre as condições do trabalho e a satisfação dos trabalhadores no local de trabalho. Este estudo é transversal quantitativo, recorrendo a profissionais que exerçam a sua atividade em lares de idosos. A amostra final compreende 118 indivíduos. Na recolha de dados foram utilizados os COPSOQ II e um questionário de avaliação das condições de trabalho. Os fatores de risco psicossociais mais percecionados foram as exigências cognitivas e emocionais, a insegurança laboral e a influência no trabalho, sendo as principais consequências para a saúde problemas em dormir, burnout e stress. Foi estabelecida uma correlação significativa positiva entre a perceção positiva das condições do local de trabalho e a satisfação no trabalho. Assim, defendemos a sensibilização para a adoção de medidas minimizadoras da exposição aos fatores de risco e os riscos psicossociais.
- Bacterial growth screened by rheologyPublication . Portela, Raquel; Pereira, M.; Sobral, Rita; Almeida, Pedro L.; R. Leal, CatarinaThe study of bacterial growth is a challenging field since it aims to describe the behaviour of microorganisms under different physical or chemical conditions. Bacterial growth as a biofilm is of particular interest as these gel-like structures are detrimental for all applications where “clean” surfaces are most important, and are related to failure of infection treatment, food spoilage and oil pipeline contamination, amongst others. In the literature one can find several works concerning the characterization of the mechanical behaviour of bacterial biofilms, although mostly are implemented over solid biofilms, as they appear in real situations [1-3], to study the adhesion properties in surfaces. In this work we applied a different technique to monitor the growth rate of a coccoid shaped bacterial species, the human pathogen Staphylococcus aureus.
- Difusão molecular em ressonância magnética para estudo de lesões mamárias malignasPublication . Jaguegivane, Seena; Janardo, J.; Pereira, M.; Fernandes, A.; Ribeiro, Margarida; Ferreira, AidaObjetivos – Com este estudo pretendeu-se i) avaliar o contributo da aplicação da sequência de difusão na caracterização das lesões mamárias malignas; ii) considerar se a sequência de difusão deve incorporar o protocolo standard em RM mamária e iii) correlacionar os resultados dos valores de coeficiente aparente de difusão (ADC) e os resultados histológicos. Metodologia – A amostra incluiu 18 pacientes do sexo feminino, com idades compreendidas entre 38 e 71 anos, que apresentavam lesões mamárias malignas confirmadas histologicamente. Foi adicionado ao protocolo de RM mamária a sequência de difusão, de modo a calcular os valores de ADC das lesões observadas. Resultados – Verificou-se que a range de valores de ADC para lesões malignas em ROI’s calculados no centro da lesão apresentavam uma média e desvio-padrão de (0,89 ± 0,14x10-3mm2/s). O método da utilização dos valores de ADC na caracterização de lesões mamárias malignas demonstrou uma sensibilidade de 100%. Conclusões – Neste estudo, com uma sensibilidade de 100%, a ponderação em difusão demonstrou ser uma técnica vantajosa na caracterização de lesões mamárias malignas pelo que se sugere a sua introdução no protocolo standard da RM mamária. ABSTRACT - Aims – The aim of this study was i) to evaluate the potential of the DWI sequence in the characterization of malignant breast lesions; ii) to verify if this sequence should incorporate the breast MRI protocol and iii) to correlate the apparent diffusion coefficients (ADC) values and histological results. Methodology – The sample includes 18 female patients between the ages of 38 and 71 years, who presented with malignant breast lesion confirmed by histology. The DWI sequence was added to the MRI standard protocol to calculate the ADC values. Results – In the results obtained we observed that the range of the ADC values calculated in the center of the malignant lesions, showed a mean and standard deviation of 0.89 ± 0.14 x10-3 mm2 / s. This method of using the ADC values for the detection of malignant lesions showed a sensitivity of 100%. Conclusion – The DWI technique proved to be a useful method in the characterization of malignant breast lesions, as it showed a sensitivity of 100%, so we suggest its inclusion in the Breast MR standard protocol.
- Following micelles with rheo-NMRPublication . Almeida, Pedro L.; Feio, G.; Pereira, M.; Scheven, U.; R. Leal, CatarinaThe rheological behaviour of the micellar system Cetyltrimethylammonium Bromide (CTAB)/Sodium Salicylate (NaSal) in water is highly dependent on the components concentration and temperature. The surfactant CTAB forms spherical micelles in water above a certain concentration (CD), which upon addition of a salt (NaSal) elongate to form entangled wormlike structures, also known as “living polymers”. The viscosity of wormlike micelles solutions increases dramatically with the increase of salt concentration (CS), changing from quasi-newtonian to a viscoelastic behaviour in the gel-like, highly entangled state. Such rich rheological behaviour has already been characterized by some of the authors and in the literature, e.g., [1-3]. The rheological behaviour of CTAB/NaSal aqueous solutions in the regime CD/Cs>1 are presented in this work. Furthermore, we followed the rheological behaviour of these solutions by a rheo-NMR technique, allowing for an insight of “what happens” inside the sample during the application of a shear flow. To achieve this goal we performed quantitative flow rate measurements using velocity NMR mapping in the rheo-NMR experiments, developed by Callaghan [4]. Attempts to characterize the velocity profile in this system has already been described [5] using an optical-shear flow experimental setup, although for solutions with CD/Cs<1, where the surfactant [CTAB] has always a smaller concentration than the salt [NaSal].
- Reversible photorheology in solutions of cetyltrimethylammonium bromide, salicylic acid, and trans-2,4,40 -trihydroxychalconePublication . Pereira, M.; R. Leal, Catarina; Parola, A. J.; Sheven, U. M.We show photorheology in aqueous solutions of weakly entangled wormlike micelles prepared with cetyltrimethyl-ammonium bromide (CTAB), salicylic acid (HSal), and dilute amounts of the photochromic multistate compound trans-2,4,40 -trihydroxychalcone (Ct). Different chemical species of Ct are associated with different colorations and propensities to reside within or outside CTAB micelles. A light-induced transfer between the intra- and intermicellar space is used to alter the mean length of wormlike micelles and hence the rheological properties of the fluid, studied in steady-state shear flow and in dynamic rheological measurements. Light-induced changes of fluid rheology are reversible by a thermal relaxation process, at relaxation rates which depend on pH and which are consistent with photochromic reversion rates measured by UV-vis absorption spectroscopy. Parameterizing viscoelastic rheological states by their effective relaxation time τc and corresponding response modulus Gc, we find the light and dark states of the system to fall onto a characteristic state curve defined by comparable experiments conducted without photosensitive components. These reference experiments were prepared with the same concentration of CTAB, but different concentrations of HSal or sodium salicylate (NaSal), and tested at different temperatures.