Resumo No presente estudo, pós de hidroxiapatita e hidroxiapatita substituída com zinco foram sintetizados utilizando-se casca de ovo de avestruz como fonte de cálcio. As amostras foram analisadas por microscopia eletrônica de varredura com fonte de emissão de campo e difração de raios X (DRX) para identificação das fases presentes, e por espectroscopia de fluorescência de raios X para análise química quantitativa dos pós sintetizados e tratados termicamente. A técnica de espectroscopia de infravermelho por transformada de Fourier foi utilizada antes e após tratamentos térmicos a 700, 900 e 1100 °C, a fim de identificar os grupos funcionais, como uma técnica complementar a DRX. Os resultados apresentados neste estudo representam um método promissor para a síntese de hidroxiapatita e hidroxiapatita parcialmente substituída com zinco, uma vez que os resultados não mostraram a presença de fases indesejáveis ou impurezas nos pós produzidos. Constatou-se que as amostras sintetizadas com Zn apresentaram maior estabilidade térmica do que as amostras de hidroxiapatita pura.

Abstract In the present study, hydroxyapatite and Zn-substituted hydroxyapatite powders were synthesized using ostrich eggshell as a calcium source. The samples were analyzed by scanning electron microscopy with field emission gun, and X-ray diffraction (XRD) to identify the present phases, and X-ray fluorescence spectroscopy for quantitative chemical analysis of the synthesized and heat treated powders. The Fourier transform infrared spectroscopy technique was used before and after heat treatments at 700, 900 and 1100 °C in order to identify the functional groups present, as an additional technique to the XRD analysis. The results presented in this study represent a promising method for synthesis of hydroxyapatite and hydroxyapatite partially substituted with zinc, since the results showed no undesirable phases or impurities in the produced powders. It was observed that Zn-substituted hydroxyapatite showed higher thermal stability, when compared to pure hydroxyapatite.

A espectrofotometria por infravermelho com transformada de Fourier (FTIR) está, presentemente, na linha da frente da análise em rotina de vinho. Com esta metodologia emergente é possível obter-se uma elevada produção de informação num curto período de tempo. Entretanto, é geralmente aceite que, para se progredir com sucesso, deve ser executado e meticulosamente seguido um sistema rigoroso de controlo da qualidade de resultados analíticos, sendo hoje em dia uma preocupação para a comunidade científica internacional enológica (OIV 2009). Neste trabalho, os autores vêm propor uma nova aproximação estratégica para o controlo da qualidade dos resultados obtidos pela análise do vinho por FTIR que tem vindo a ser seguida em rotina no Instituto dos Vinhos do Douro e do Porto (IVDP). São apresentados exemplos para a massa volúmica (g/mL), titulo alcoométrico volúmico (% v/v), valor de pH , acidez volátil (g/L) e acidez total (g/L).

The Fourier Transform Infrared (FTIR) spectrophotometry is, at present, in the front line of routine wine analysis. With this emerging methodology it is possible to obtain a great throughput of information in a very short time. However, it is being commonly accepted that, in order to proceed successfully, a rigorous system of quality control of analytical results must be implemented and meticulously followed, being this, nowadays, a major concern for the international oenological scientific community (OIV 2009). In the present paper, the authors are proposing a new strategic approach for the quality control of results obtained through analysis with FTIR, which is being followed in routine at Port and Douro Wines Institute (IVDP). Examples are given for wine density (g/mL), alcoholic strength (% v/v), pH, volatile acidity (g/L) and total acidity (g/L).

This work contains a novel approach for the study of stability in fluidized systems. It includes the influence of solid particle kinetic energy variations, which are known as granular temperature. The stability is verified by the temporal evolution of bed fluid-dynamics properties (solid volumetric fraction, fluid velocity, solid particles velocity) after small perturbations. The bed is stable when the amplitudes of perturbations decrease with time. The work departs from the mass and momentum continuity equations for the solid and fluid phase, as proposed by Anderson and Jackson (1968). Those are complemented by an equation describing the energy balance from the point of view of granular temperature. Then, a linear approximation for the equations after the introduction of small magnitude perturbations is obtained. The application of harmonic solutions allows arriving to the temporal description of the perturbations. Results show the occurrence of instabilities on the direction transverse to gravity. This cannot be observed by previous approaches (Anderson and Jackson, 1968, 1969; Homsy et al., 1980; Liu, 1982). The present work also suggests a new mechanism for the formation of bubbles in fluidized systems. The parametric influence of the model on the stability of fluidized systems is also verified.