Diagnóstico do parto pré-termo pela medida ultrassonográfica do comprimento do colo uterino

OBJETIVO: Medir o comprimento do colo uterino, utilizando a ultrassonografia transvaginal, em pacientes com quadro clínico compatível com ameaça de parto pré-termo, e correlacionar a medida do colo uterino, em cada caso, com a interrupção espontânea da gravidez dentro de sete dias. MATERIAIS E MÉTODOS: Foram realizados exames ultrassonográficos em 72 pacientes com quadro clínico compatível com ameaça de parto pré-termo. RESULTADOS: A sensibilidade do exame foi de 90,5%, a especificidade, de 98%, o valor preditivo positivo, de 95%, e o valor preditivo negativo, de 96%. A análise foi realizada utilizando-se a medida de 15 mm de comprimento do colo uterino como valor preditivo do parto pré-termo. CONCLUSÃO: Parece ser possível prever o parto pré-termo em pacientes com colo uterino menor que 15 mm. Tal observação poderá trazer contribuição para a administração mais oportuna de corticoides, com o intuito de acelerar a maturidade pulmonar fetal.

Diagnóstico por imagem e aspectos clínicos da trombose venosa cerebral em recém-natos a termo sem dano cerebral: revisão em 10 anos

OBJETIVO: Descrever e comparar os métodos de imagem e os aspectos clínicos em quatro recém-natos a termo diagnosticados como trombose venosa cerebral, sem dano encefálico, adscritos a uma unidade de terapia intensiva neonatal. MATERIAIS E MÉTODOS: Revisão em 10 anos com quatro casos diagnosticados como trombose venosa cerebral por meio de ultrassonografia transfontanela com Doppler e confirmados por ressonância magnética/angiorressonância, correlacionados aos aspectos clínicos e evolução neurológica. RESULTADOS: A ultrassonografia foi normal em 75% dos casos e a ressonância magnética, em 100%. No caso alterado, a dilatação venosa foi identificada. O Doppler e a angiorressonância estavam alterados em 100% dos casos. Dos aspectos clínicos, a hipóxia (100%) e a convulsão precoce (100%) predominaram, com potencial evocado alterado em 50% dos casos. Na avaliação do neurodesenvolvimento, todas as áreas estiveram dentro da normalidade até a última avaliação. CONCLUSÃO: A ultrassonografia associada ao Doppler é capaz de identificar as alterações da trombose venosa cerebral, devendo ser complementada com a ressonância magnética, que é o padrão ouro de diagnóstico.

Estudo dos ventrículos cerebrais por ultrassonografia, na criança normal, nascida a termo, de 1 a 6 meses

OBJETIVO: Estudo dos ventrículos cerebrais por ultrassonografia, com o objetivo de estabelecer de forma simplificada parâmetros para diagnóstico das dilatações ventriculares leves. MATERIAIS E MÉTODOS: Foram estudadas, prospectivamente, 105 crianças, normais, nascidas a termo, com um total de 181 exames realizados, mensalmente até os 6 meses, através da observação de dados morfológicos e medidas. As medidas efetuadas foram: índice ventrículo/hemisfério, diâmetro anteroposterior do corno anterior e do quarto ventrículo. RESULTADOS: Obtiveram-se média, desviopadrão e percentis de normalidade das medidas estabelecidas, em cada faixa etária. A pesquisa de halo anecoico nos dois terços posteriores do plexo coroide em plano coronal VI, para avaliação dos cornos temporal/posterior, foi ausente, e o terceiro ventrículo mostrou-se como uma fenda anecoica, menor que 1 mm, em plano coronal V em todas as crianças do estudo. CONCLUSÃO: Os achados morfológicos relacionados aos cornos temporal/posterior e ao terceiro ventrículo, associados ao percentil 95 das medidas como limite superior da normalidade, podem ser utilizados para diagnóstico simplificado de dilatações ventriculares leves.

Determinação permanganimétrica de íons Fe3+ com o uso de zinco metálico como redutor - uma contribuição ao ensino de química analítica

The classical volumetric titration of Fe2+ with MnO4-, used in some routine analysis as well as in undergraduate courses was improved. SnCl2 (to reduce Fe3+ to Fe2+) and HgCl2 (to oxidize excess SnCl2) were substituted by metallic zinc in boiling solutions, thus avoiding the toxic HgCl2 and Hg2Cl2; nitrate ions do not interfere in the improved methodology (it is an interference in the classical one) and the reproducibility of the determinations is increased by using metallic zinc. Determinations by students of undergraduate courses are discussed.

Baterias de níquel-hidreto metálico, uma alternativa para as baterias de níquel-cádmio

Nickel metal hydride (Ni-MH) batteries have emerged as an alternative for replacement of nickel-cadmium batteries, because of their more environmental compatibility and high energy capacity. In this article, we described the properties and applications for Ni-MH batteries, giving some emphasis on the metal-hydride electrode, including the description of composition, the charge storage capacity and the discharge profile. The key component of the nickel-metal hydride electrode is a hydrogen storage alloy whose composition is formulated to obtain a high stable material over a large number of charge-discharge cycles.

Metodologia para obtenção de parâmetros de mecânica molecular aplicados a compostos de coordenação

A methodology is presented to obtain force field parameters to be used in molecular mechanics. The case of Ru(II) is investigated and the parameters obtained, specially its covalent radii, are employed to model Ru(II) coordination compound. The combined use of molecular mechanics with ab initio methods allowed us to predict the metal-ligand stretching force constant for Ru(II) coordination compounds.

Síntese e caracterização de alfa-fosfato de zircônio(IV) contendo agregados de cobre metálico

The alpha-zirconium (IV) hydrogenphosphate (alpha-ZrP) has received great attention in the last years due to its properties like ion exchange, intercalation, ionic conductivity and catalytic activity. This work reports a method to produce metallic copper clusters on alpha-ZrP to be used as catalysts in petrochemical processes. It was found that the solids were non-crystalline regardless of the uptake of copper and the reduction. The specific surface area increased as a consequence of the increase of the interlayer distance to accept the copper ions between the layers. During the reduction, big clusters of copper (0,5-11µ) with different sizes and shapes were produced.

Degradação de corantes reativos pelo sistema ferro metálico/peróxido de hidrogênio

In this work the degradation of aqueous solutions of reactive azo-dyes is reported using a combined reductive/advanced oxidative process based in the H2O2/zero-valent iron system. At optimized experimental conditions (pH 7, H2O2 100 mg L-1, iron 7 g L-1) and using a continuous system containing commercial iron wool, the process afforded almost total discolorization of aqueous solutions of three reactive azo-dyes (reactive orange 16, reactive black 5 and brilliant yellow 3G-P) at a hydraulic retention time of 2.5 min. At these conditions the hydrogen peroxide is almost totally consumed while the released total soluble iron reaches a concentration compatible with the current Brazilian legislation (15 mg L-1).

Estudo de homogeneidade de lote de material silício metálico candidato a material de referência

From the perspective of the uncertainties in chemical measurements all uncertainty sources should be part of the uncertainty of the reference material. When the primary methods are not available, interlaboratorial comparisons are used as a means of certification. The material to be distributed to the laboratories should have its homogeneity confirmed. The uncertainty due to this factor will be added to the characterization uncertainty. This work presents a homogeneity study of a lot of silicon metal of chemical degree where the uncertainty due to inhomogeneity is obtained using analysis of variance.

Efeito do teor metálico em catalisadores Co/Al2O3 aplicados à reação de reforma a vapor de etanol

The development of cobalt catalysts to produce hydrogen from ethanol is the goal of this investigation. Co/Al2O3 catalysts were prepared by impregnation and characterized by atomic absorption, nitrogen adsorption, X-ray diffraction, Raman spectroscopy, temperature programmed reduction and carbon analysis. The catalysts contained Co3O4 oxide and Co3+ and Co2+ species interacting with alumina. The cobalt load affects the crystal size and the crystalline structure and higher Co loads influence the reaction mechanism, changing the selectivity of the catalysts, decreasing the amount of CO produced and avoiding the formation of products catalyzed by the support. The ethanol conversion was 50-70% with 10-<1% of CO in the hydrogen.

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.

Obtenção de titânio metálico com porosidade controlada por metalurgia do pó

Titanium is an attractive material for structural and biomedical applications because of its excellent corrosion resistance, biocompatibility and high strength-to-weight ratio. The high reactivity of titanium in the liquid phase makes it difficult to produce it by fusion. Powder metallurgy has been shown to be an adequate technique to obtain titanium samples at low temperatures and solid-phase consolidation. The production of compacts with different porosities obtained by uniaxial pressing and vacuum sintering is briefly reviewed. Powder particle size control has been shown to be very important for porosity control. Sample characterization was made using scanning electron microscopy (SEM) images.

Análise dinâmico-mecânica: aplicações em filmes comestíveis

Edible films are thin materials based on biopolymers and food additives. The aim of this work is a review on the application of dynamic mechanical analysis in edible film technology. After a brief review of the linear visco-elasticity theory, a description of some practical aspects related to dynamic mechanical analysis, such as sample fixation and sample dehydration during analysis and types and modes of tests are presented. Thus, the use of temperature scanning analysis for glass transition and for plasticizer-biopolymer compatibility studies and frequency scanning tests, less common in edible film technology, are critically reviewed.

Nanocompósitos cerâmicos a partir do processo de moagem mecânica de alta energia

Pb/Ti, Sn and Mg-based nanocomposite materials were prepared by the high-energy mechanical milling of commercial powders. The surface of these ceramic compounds was strongly influenced by the doping, diameter of the milling spheres and time of the mechanical milling (amorphization process). Such milling leads to the formation of nanocrystalline materials. The mechanical processing parameters of these compounds were investigated through Brunauer, Emmett and Teller isotherms, wide angle X-ray diffraction, transmission electron microscopy and CO2 adsorption.

Síntese do pigmento cerâmico verde vitória (Ca3Cr2Si3O12) a partir de CaCO3, Cr2O3 e SiO2

The synthesis of the ceramic pigment Victoria Green (Ca3Cr2Si3O12 ) is described. As raw materials CaCO3, Cr2O3, and SiO2 obtained from rice husk were used. Borax was used as mineralizer. Raw materials were formulated stoichiometrically and calcined from 1000 to 1200 ºC for 180 min. The main phase detected was uvarovite with particle size below 45 mm. The pigments were applied on ceramic tiles and sintered at 1150 ºC for 40 min. The synthesis process showed to be adequate to produce the green pigment, whose characteristics resemble those of a commercial pigment.