Contraste hepatobiliar: diagnóstico diferencial das lesões hepáticas focais, armadilhas e outras indicações

A caracterização das lesões hepáticas focais é muito importante. A ressonância magnética é considerada o melhor método de imagem para a avaliação destas lesões, mas não permite o diagnóstico em todos os casos. Os contrastes hepatobiliares aumentam a acurácia diagnóstica da ressonância magnética e diminuem o número de lesões hepáticas indefinidas. Suas principais indicações são a diferenciação entre hiperplasia nodular focal e adenoma, caracterização de carcinoma hepatocelular em pacientes cirróticos, detecção de metástases hepáticas pequenas, avaliação da anatomia biliar e identificação de fístulas biliares pós-operatórias. A utilização dos contrastes hepatobiliares pode reduzir a necessidade de procedimentos diagnósticos invasivos e de avaliação complementar por outros exames de imagem, além de diminuir a necessidade de exames de acompanhamento.

Repercussões clínicas e radiológicas do neurofibroma plexiforme na região pélvica

Descrição de caso de neurofibroma plexiforme localizado na região pélvica comprometendo bexiga, próstata e coluna lombossacra, com evolução de três anos e seis meses. Diante de contraindicação de remoção cirúrgica, foi realizado acompanhamento clínico e radiológico semestral, sem constatação de crescimento tumoral. Na neurofibromatose tipo 1, as manifestações clínicas são diversas e a equipe médica deve estar atenta à investigação complementar e pode ser surpreendida por um achado raro. As massas pélvicas volumosas podem, eventualmente, corresponder a neurofibromas plexiformes, sendo útil a investigação de neurofibromatose caso o paciente ainda não tenha esse diagnóstico.

Ultra-trace monitoring of copper in environmental and biological samples by inductively coupled plasma atomic emission spectrometry after separation and preconcentration by using octadecyl silica membrane disks modified by a new schiff's base

Ultra-trace amounts of Cu(II) were separated and preconcentrated by solid phase extraction on octadecyl-bonded silica membrane disks modified with a new Schiff,s base (Bis- (2-Hydroxyacetophenone) -2,2-dimethyl-1,3-propanediimine) (SBTD) followed by elution and inductively coupled plasma atomic emission spectrometric detection. The method was applied as a separation and detection method for copper(II) in environmental and biological samples. Extraction efficiency and the influence of sample matrix, flow rate, pH, and type and minimum amount of stripping acid were investigated. The concentration factor and detection limit of the proposed method are 500 and 12.5 pg mL-1, respectively.

Distribuição de metais pesados em sedimentos do sistema estuarino da Ilha de Vitória-ES

Heavy-metal concentration in sediment is an important parameter for identifying pollution sources and assessing pollution levels in aquatic ecosystems. In this context, the present study aimed at determining concentrations of heavy metals in sediments from the Vitória estuarine system, Brazil. Twenty nine stations were surveyed to assess the spatial distribution of heavy metals. The metals for silt-clay fractions (<63 µm) were analyzed through atomic absorption spectrometry. A discriminant analysis segregated the stations in four groups representing four areas within the estuarine system. The Espírito Santo Bay showed the lowest metal concentrations, while the Vitória harbor canal showed the highest. We concluded that concentrations of heavy metals reflect natural conditions and the contribution of human activities from sewage and industrial effluents. It was not possible to directly associate metal concentrations to specific pollution sources.

A novel method for fast enrichment and monitoring of hexavalent and trivalent chromium at the ppt level with modified silica MCM-41 and its determination by inductively coupled plasma optical emission spectrometry

Chromium(III) at the ng L-1 level was extracted using partially silylated MCM-41 modified by a tetraazamacrocyclic compound (TAMC) and determined by inductively coupled plasma optical emision spectrometry (ICP OES). The extraction time and efficiency, pH and flow rate, type and minimum amount of stripping acid, and break- through volume were investigated. The method's enrichment factor and detection limit are 300 and 45.5 pg mL-1, respectively. The maximum capacity of the 10 mg of modified silylated MCM-41 was found to be 400.5±4.7 µg for Cr(III). The method was applied to the determination of Cr(III) and Cr(VI) in the wastewater of the chromium electroplating industry and in environmental and biological samples (black tea, hot and black pepper).

Vanadium-modified molecular sieves: preparation, characterization and catalysis

Vanadium-containing molecular sieves are redox catalysts and are good candidates as substitutes for oxide-supported V2O5 in a number of reactions. These materials have the advantage of presenting better dispersion of vanadium species, as well as shape-selective properties and controllable acidities. They may be prepared by one-pot synthesis or by post-synthesis methods and a number of techniques such as diffuse reflectance UV-visible spectroscopy, 51V nuclear magnetic resonance and electron paramagnetic resonance, to name but a few, have been used to characterize these materials. In this review, methods of preparation of vanadium-modified molecular sieves, their characterization and applications in catalysis are discussed.

Estudio cinético de la descomposición catalizada de peróxido de hidrógeno sobre carbón activado

The kinetic study of decomposition of hydrogen peroxide catalyzed by activated carbon was carried out. The effect of concentrations of reactants and temperature were experimentally studied. Kinetic data were evaluated using differential method of initial rates of reaction. When a typical kinetic law for reactions in homogeneous phase is used, first order of reaction is obtained for hydrogen peroxide and activated carbon, and activation energy of 27 kJ mol-1 for the reaction was estimated. Experimentally was observed that surface of activated carbon is chemically modified during decomposition of hydrogen peroxide, based on this result a scheme of reaction was proposed and evaluated. Experimental data fits very well to a Langmuir- Hinshelwood kinetic model and activation energy of 40 kJ mol-1 was estimated for reaction in heterogeneous phase.

On-line preconcentration system using a microcolumn packed with Alizarin Red S-modified alumina for zinc determination by flame atomic absorption spectrometry

A simple and sensitive on-line flow injection system for determination of zinc with FAAS has been described. The method is based on the separation and preconcentration of zinc on a microcolumn of immobilized Alizarin Red S on alumina. The adsorbed analyte is then eluted with 250 µL of nitric acid (1 mol L-1) and is transported to flame atomic absorption spectrometer for quantification. The effect of pH, sample and eluent flow rates and presence of various cations and anions on the retention of zinc was investigated. The sorption of zinc was quantitative in the pH range of 5.5-8.5. For a sample volume of 25 mL an enrichment factor of 144 and a detection limit (3S) of 0.2 µg L-1 was obtained. The precision (RSD, n=7) was 3.0% at the 20 µg L-1 level. The developed system was successfully applied to the determination of zinc in water samples, hair, urine and saliva.

Estudio comparativo de la ozonización de aceites de girasol modificados genéticamente y sin modificar

Ozonation of sunflower oils with genetic modification High Oleic and High Oleic-Palmitic (AO and PO respectively) and without modification, High Linoleic (AL) at different applied ozone dosages was carried out with measurement of peroxide and acidity indexes values, fatty acids composition, oxygen percentage content and antimicrobial activity. The comparison of peroxides indexes and oxygen content at different applied ozone dosages in each oil showed good correlation (r = 0,99). Higher amount of oleic acid was consumed at higher applied ozone dosage in PO oil than AO oil, which can be related to the increase of acidity index. The antimicrobial activity was better for AL and PO ozonized oils.

Poliuretanos elastoméricos obtenidos a partir de aceite de ricino y almidón de yuca original y modificado con anhídrido propiónico: síntesis, propiedades fisicoquímicas y fisicomecánicas

Chemical modification of cassava starch was conducted through an acylation reaction by using pyridine and propionic anhydride to replace the functional groups of starch. Polyurethane elastomers were prepared using suspensions of the mixture obtained from castor oil and yucca starch that was modified by a propionic anhydride reaction. The suspensions were characterized by means of tests based on The Fourier Transform Infrared Spectroscopy and the Hydroxyl Index. The castor oil-AMP suspensions were used for the PU synthesis. The PUs were characterized by their physical-mechanical properties like tension- deformation and Shore A. hardness, thermal gravimetric analysis and swelling test. The density cross-linking of from swelling tests was determined by applying the Flory-Rehner equation.

Separation and preconcentration trace amounts of gold by using modified organo nanoclay closite 15A

The application of organo nanoclay 5-(4-dimethylamino-benzylidene) rhodanine-immobilized as a new, easily prepared, and stable solid sorbent for preconcentration trace amounts of Au(III) ions in aqueous solution is presented. The sorption of Au(III) ions was quantitative in the pH range of 2-4, and quantitative desorption occurred instantaneously with 10.0 mL of a mixture containing 0.5 mol L-1 Na2S2O3 and KSCN. Various parameters, such as the effect of pH, breakthrough volume, extraction time, and interference of a large number of anions and cations have been studied. The proposed method has been applied for determination of trace amount of gold in water samples.

Diesel/biodiesel soot oxidation with ceo2 and ceo2-zro2-modified cordierites: a facile way of accounting for their catalytic ability in fuel combustion processes

CeO2 and mixed CeO2-ZrO2 nanopowders were synthesized and efficiently deposited onto cordierite substrates, with the evaluation of their morphologic and structural properties through XRD, SEM, and FTIR. The modified substrates were employed as outer heterogeneous catalysts for reducing the soot originated from the diesel and diesel/biodiesel blends incomplete combustion. Their activity was evaluated in a diesel stationary motor, and a comparative analysis of the soot emission was carried out through diffuse reflectance spectroscopy. The analyses have shown that the catalyst-impregnated cordierite samples are very efficient for soot oxidation, being capable of reducing the soot emission in more than 60%.

Poly(o-methoxyaniline) modified electrode for detection of lithium ions

This paper reports the use of an electrode modified with poly(o-methoxyaniline) for detecting lithium ions. These ions are present in drugs used for treating bipolar disorder and that requires periodical monitoring of the concentration of lithium in blood serum. Poly(o-methoxyaniline) was obtained electrochemically by cyclic voltammetry on the surface of a gold electrode. The results showed that the electrode modified with a conducting polymer responded to lithium ions in the concentration range of 1 x 10-5 to 1 x 10-4 mol L-1 . The results also confirmed that the performance of the modified electrode was comparable to that of the standard method (atomic emission spectrophotometry).

Estudio de la contaminación por metales en sedimentos acuáticos de la Bahía de Matanzas

Surface sediments of the Bay of Matanzas (Cuba) were studied to assess its environmental quality by using several criteria (metal content index, pollution load index and sediment quality guidelines). Two partial digestion sediment procedures and a modified BCR sequential extraction were used. The concentrations of metals were measured by atomic spectroscopy methods. The founded contents of Cu (2,4-27,9 mg kg-1), Zn (2,5-55,5 mg kg-1) and Ni (8,8-99,2 mg kg-1) were below those reported by other authors. The results obtained suggested that the most polluted sites were 3, 5, and 6. The sequential extraction procedure showed that most of the studied metals were associated to the more stable fractions.

Highly improved chromium (III) uptake capacity in modified sugarcane bagasse using different chemical treatments

The present paper focuses on improving chromium (III) uptake capacity of sugarcane bagasse through its chemical modification with citric acid and/or sodium hydroxide. The chemical modifications were confirmed by infrared spectroscopy, with an evident peak observed at 1730 cm-1, attributed to carbonyl groups. Equilibrium was reached after 24 h, and the kinetics followed the pseudo-second-order model. The highest chromium (III) maximum adsorption capacity (MAC) value was found when using sugarcane bagasse modified with sodium hydroxide and citric acid (58.00 mg g-1) giving a MAC value about three times greater (20.34 mg g-1) than for raw sugarcane bagasse.