Angiotomografia com múltiplos detectores no diagnóstico de drenagem venosa pulmonar anômala: experiência inicial

OBJETIVO: Demonstrar que a angiotomografia computadorizada com múltiplos detectores é um método efetivo e não invasivo para o diagnóstico de drenagem venosa pulmonar anômala. MATERIAIS E MÉTODOS: Estudo retrospectivo de 2.905 angiotomografias computadorizadas com múltiplos detectores cardíacas realizadas em nosso serviço no período de julho de 2003 a novembro de 2007. Destas, 393 foram destinadas para avaliar cardiopatias congênitas e as 2.512 restantes, para analisar as artérias coronárias. RESULTADOS: Foram encontrados 21 casos de drenagem venosa pulmonar anômala, sendo 7 (33,3%) do tipo total e 14 (66,7%) do tipo parcial. Das drenagens venosas pulmonares anômalas totais, três foram do tipo supracardíaco, três do tipo infracardíaco e uma do tipo cardíaco. CONCLUSÃO: A angiotomografia computadorizada com múltiplos detectores tem demonstrado fundamental importância no diagnóstico destas anomalias, principalmente por se tratar de método não invasivo capaz de analisar estruturas intra e extracardíacas e por permitir um estudo completo da anatomia torácica, contribuindo sobremaneira na conduta cirúrgica e, consequentemente, no prognóstico destes pacientes, especialmente por diagnosticar malformações não suspeitadas clinicamente

Influência da adição de defloculante, ligante e partículas de alumina no comportamento reológico de suspensões a base de frita e caulim

Enamel suspensions were characterized according to their rheological behavior. The suspensions presented a pseudoplastic behavior, yield stress and thixotropy, with or without the presence of deffloculant. Added carboxymethylcellulose increases the apparent viscosity of enamel suspensions and interacts complexly with the deffloculant, here sodium silicate. Addition of crystalline particles of two types of alumina, used to improve the wear resistance of ceramic glazes, also change strongly the rheological behavior of the suspensions. Added high specific area, irregular alumina particles produce a higher increase of the apparent viscosity of enamel suspensions compared to rounded ones.

Recuperação de 241Am de para-raios e detectores de fumaça

A method is described for recovering and purifying 241Am from lightning-conductors and smoke detectors. The method is based on the precipitation of silver, as AgCl, the main impurity, and extraction of americium with TBP. Further purification with ion-exchange resin is also used. The results have shown that by this method the americium is obtained with high purity.

Partículas nanométricas de ferritas de ítrio

Nanoparticles of yttrium iron garnet (YIG) were obtained by coprecipitation. The particles were prepared by hydrolysis in acid medium with addition of ammonia or urea, for homogeneous nucleation, at 90ºC. Different compositions and spherical morphologies were achieved by changing reactants concentrations and precipitation agent. X-ray diffractometry, transmission electron microscopy, differential thermal analysis and electrophoretic mobility were carried out on these particles to investigate the obtained phase, phase transition temperature, morphology, particle size and zeta potential, respectively.

Estudo das partículas totais em suspensão e metais associados em áreas urbanas

This work aims at the study of the air quality determination regarding the total suspended particles (TSP) and the associated metals in the counties of Charqueadas and Sapucaia do Sul at the state of Rio Grande do Sul. The TSP samples were collected using high volume samplers and the analysis of the metallic elements was accomplished through ICP-AES. The results revealed that the TSP concentrations, found in the two studied regions, have exceded the current air quality patterns established by the Brazilian Legislation. They also revealed high levels of several of the elements being attributed to the presence of anthropogenic sources. The correlation between meteorological data (speed and wind direction) and TSP concentrations were significant and revealed strong influence in particle dispersion.

Detectores potenciométricos para sistemas de análise por injecção em fluxo, evolução e aplicação

The field of flow injection potentiometry (FIP) is reviewed and its current status assessed. The research development and application of electrodes in flow injection systems are presented and discussed.

Análises seqüenciais de agrupamentos aplicadas ao estudo de partículas atmosféricas

The present paper has as objective to apply a sequential Cluster Analysis to the atmospheric particles: Hierarchical Cluster Analysis followed by Nonhierarchical Cluster Analysis. The hierarchical cluster analysis results were used as start point for the nonhierarchical cluster analysis as an agglomerative technique. These particles were taken from two areas of the metropolitan region of Porto Alegre, Charqueadas and Sapucaia do Sul., from may /97 to may/98, using a High Volume Sampler (Hi-Vol). Around 10,000 particles were analysed by Scanning Electron Microscope with Energy-Dispersive X-Ray microanalysis (SEM-EDS). The Hierarchical Cluster Analysis allowed the identification of five groups of particles, whose amounts were differentiated according to the summer and the winter campaigns. The abundance of each type of particles inside each group according to the different sections was verified by the Nonhierarchical Cluster Analysis, resulting in information about the emissions sources. The groups of particles of Si/Al and Si and of Fe/Zn and Fe for Charqueadas were more significant in section 2 and 3 (NW and W wind directions) and in section 1 (SE wind direction), evidencing the influence of the coal power plant and steel industry, respectively located in these quadrants. In Sapucaia do Sul the data were more heterogeneous, causing a certain difficulty to identify the source as anthropogenic. Nevertheless the group of particles containing Fe was found in sectors of NW/W wind directions which shows the influence of the steel plant.

Estudo do efeito do tratamento superficial por moagem sobre as propriedades das partículas de uma liga de hidreto metálico

This work reports results of studies on the electrochemical and structural properties of a Ti/Zr-based metal hydride alloy covered by Ni and LaNi4,7Sn0,3 powder additives by ball milling. The effect of this treatment is investigated for the activation time, hydrogen storage capacity and equilibrium pressure, cycling stability and the hydration/dehydration kinetics. Charge and discharge cycles show a significant decrease of the activation time due to an increase of the active area caused by the milling treatment, independent of the additive. However, other results have evidenced little effect of the milling surface treatment on the charge storage capacity, hydrogen equilibrium pressure, and hydration/dehydration kinetics, for both the Ni and LaNi4,7Sn0,3 covered materials.

Determinação de isotiocianato de benzila em Carica papaya utilizando cromatografia gasosa com detectores seletivos

In the present work, a method was developed and validated for the quantification of benzyl isothiocyanate (BITC) in the fruits of Carica papaya. The quantification of this compound was carried out by gas chromatography (GC) with selective detectors - nitrogen phosphorus detector (NPD) and flame photometric detector (FPD). The performance of these detectors showed a higher sensitivity of the NPD with a broader linear range of detection. The LOD/LOQ were 0.038/0.100 µg/mL for NPD and 5.78/19.29 µg/mL for FPD. The recovery of the method for BITC was 90,64%. An average value of BITC concentration in all the analyzed samples was 16,23 µg BITC/g.

Hidrogenação eletrocatalítica de substratos orgânicos utilizando eletrodos modificados poliméricos contendo partículas de Ni/Pd e Ni/Pt

Novel modified electrodes bearing dispersed Pd and Pt particles have been prepared from poly (allyl ether of the p-benzenesulfonic acid) films with incorporated nickel particles making use of galvanic displacement reactions. The SEM analysis of the new modified electrodes revealed efficient deposition of Pd but weak up-take of Pt. Electrocatalytic hydrogenation of several classes of organic substrates were carried out using the MEs Ni, Ni/Pd and Ni/Pt. The Ni/Pd ME showed to be the best of them for the hydrogenation of double, triple and carbonyl bonds. The complete hydrogenation of the aromatic rings for the well-adsorbed substrates acetophenone and benzophenone is noteworthy.

Adsorção do corante azul de metileno em partículas de argilominerais: análise dos tamanhos das partículas

Interactions of cationic dye methylene blue (MB) with clay particles in aqueous suspension have been extensively studied. As already known, the number of natural negative charges on the clay modifies significantly the particle sizes dispersed in water and therefore the nature of the interaction with the dye. This work evaluated with UV-Vis spectroscopy method how the clay particle sizes weighted on the adsorption and rearrangement of the dye molecules in aqueous system. The results obtained from light-scattering measurements confirmed that larger particles are found in suspensions containing the high-charged clays as the visible absorption band related to the MB aggregates (570 nm) on these suspensions prevailed.

Determinação de peróxido de hidrogênio em antisséptico bucal usando um microdispositivo contendo partículas de Azul da Prússia

A simple flow-injection amperometric procedure using a three-electrode-integrated sensor for the determination of H2O2 in antiseptic mouthwash is reported. This method involves the use of a working composite electrode modified with Prussian Blue (PB) particles that was easily adapted as detector in FIA. The best amperometric response was observed for a composite containing 30% of graphite modified with PB particles (GAP) and 70% of pure graphite (GR). The proposed method presents a linear response in the range of 10 to 200 μmol L-1. The detection and quantification limits were 0.8 and 2.6 μmol L-1, respectively.

Estudo de alguns esfeitos na precipitação de partículas esféricas de sílica via microemulsão inversa

Partículas esféricas de sílica foram obtidas via microemulsão inversa em sistema AOT / Heptano / H2O, utilizando-se soluções de silicato de sódio como precursor. Variações de condições experimentais durante a precipitação levam à mudanças no tamanho e na forma das partículas. O objetivo deste trabalho é otimizar a obtenção de partículas de sílica com homogeneidade de forma e tamanho, variando-se a ordem de adição dos reagentes, a concentração da solução de silicato de sódio, a razão água/surfactante (W), a ordem de mistura dos reagentes e a purificação do produto obtido. As micrografias evidenciaram que para se obter partículas esféricas, com faixa estreita de tamanho, utiliza-se duas microemulsões inversas a partir das soluções de ácido nítrico e de silicato de sódio, sendo que a mistura destas deve ser feita adicionando-se a microemulsão contendo o silicato de sódio sobre a microemulsão contendo o ácido nítrico. A relação silicato de sódio:água mais adequada de para os objetivos do trabalho é de 1:10. A purificação mais eficiente é aquela feita em duas etapas, com etanol e com água quentes. A partir dos resultados obtidos, pode-se verificar também que quanto maior o W maior será o tamanho médio de partícula.

Oxidação eletroquímica do metanol sobre partículas de PtRu e PtMo suportadas em carbono de alta área superficial

A reação de eletro-oxidação do metanol foi estudada sobre eletrocatalisadores de Pt/C, PtRu/C e PtMo/C preparados pelo método do ácido fórmico em diferentes composições atômicas. Os produtos da oxidação do metanol foram monitorados pela técnica de DEMS. O desempenho dos catalisadores frente a reação de oxidação do metanol foi estudado através dos perfis voltamétricos e experimentos de cronoamperoometria.