RESUMEN Esta investigación tiene como objetivo analizar la influencia de las competencias de los profesores de Ingeniería en su desempeño, como la perciben los estudiantes de Ingeniería y los graduados de una universidad pública federal brasileña. En cuanto a la metodología, se propuso, identificó y validó un conjunto de competencias de educadores de Ingeniería mediante análisis factorial exploratorio (EFA), análisis paralelo, consistencia interna (alfa de Cronbach) y análisis factorial confirmatorio parcial (PCFA) en una muestra de 139 estudiantes de Ingeniería y graduados (ingenieros), que contestaron un cuestionario de 35 ítems. Los resultados revelan tres competencias principales (conocimiento del contenido/pedagógico, actitudes inspiradoras de innovación y habilidades emocionales) que profundizan la investigación de competencias de profesores de Ingeniería. En primer lugar, los estudiantes perciben el conocimiento del contenido-pedagógico como una sola competencia fusionada. Segundo, los estudiantes de Ingeniería necesitan no solo desarrollar competencias de innovación, sino que también los educadores de Ingeniería deben desarrollar actitudes que inspiren la innovación para motivar la capacidad de innovar de los estudiantes. En tercer lugar, las habilidades emocionales también juegan un papel importante en el desempeño de los profesores. Finalmente, el impacto de estas competencias en el desempeño de los educadores de Ingeniería se confirmó y analizó mediante una regresión logística.

ABSTRACT This research aims to analyze the influence of Engineering professors' competencies on their performance, as perceived by Engineering students and graduates from a Brazilian federal public university. Regarding methodology, a set of Engineering educators' competencies were proposed, identified, and validated by exploratory factor analysis (EFA), parallel analysis, internal consistency (Cronbach's alpha), and partial confirmatory factor analysis (PCFA) in a sample of 139 Engineering students and graduates (engineers), who answered a 35-item questionnaire. Results reveal three main competencies (namely, content-pedagogical knowledge, innovation-inspiring attitudes, and emotional skills) that further the research on the competencies of Engineering professors. First, content-pedagogical knowledge is perceived by students as a single, merged competence. Second, Engineering students not only need to develop innovation competencies, but Engineering educators also have to develop innovation-inspiring attitudes to motivate students' innovativeness. Third, emotional skills also play an important role in professors' performance. Finally, the impact of these competencies on Engineering educators' performance was confirmed and analyzed by means of a logistic regression.

Este trabalho teve por objetivo sinterizar cerâmicas de hexaferrita de bário comercial em forno de micro-ondas, visando obter propriedades magnéticas tão boas quanto aquelas obtidas por sinterização convencional. Amostras de hexaferrita de bário foram dopadas com cromo, prensadas isostaticamente e sinterizadas em forno de micro-ondas e convencional. A caracterização foi por difração de raios X, microscopia eletrônica de varredura, determinação de densidade aparente e curvas de histerese magnética. O tempo de queima da hexaferrita de bário por micro-ondas foi em menos de 20% do tempo gasto da queima convencional. As amostras apresentaram tamanho de grão um pouco inferior, densidade e magnetização de saturação semelhante às obtidas pela sinterização convencional, mostrando o alto potencial de aplicação da técnica de micro-ondas para o processamento da hexaferrita de bário comercial. A adição de óxido de cromo nas amostras de hexaferrita de bário resultou na melhoria das propriedades magnéticas.

The purpose of this work was to sinter commercial barium hexaferrite ceramic in a microwave oven, aiming to obtain magnetic properties similar to those obtained by conventional sintering. Samples of barium hexaferrite were doped with chromium, isostatically pressed and sintered in a microwave oven and a conventional furnace for comparison. The sintered samples were characterized by X-ray diffraction, scanning electron microscopy, bulk density, and magnetic hysteresis curves. Microwave sintering of the barium hexaferrite took less than 20% of the time spent in conventional sintering. The microwave sintered samples showed a somewhat smaller grain size, but their density and saturation magnetization were similar to those obtained by conventional sintering, indicating the promising potential of processing commercial barium hexaferrite by microwaves. The addition of chromium oxide to the barium hexaferrite samples improved their magnetic properties.

Nanopós de hexaferrita de estrôncio dopadas com cromo foram sintetizadas por reação por combustão. A influência do Cr3+ nas proporções de x = 0, 0,2, 0,3 e 0,4 no sistema SrCr xFe12-xO19 foi investigada. Os pós foram preparados de acordo com o conceito da química dos propelentes, aquecidos em placa convencional. Os pós sintetizados foram caracterizados por difratometria de raios X, microscopia eletrônica de varredura e medidas magnéticas. Os resultados mostraram que foi possível obter nanopós de hexaferrita de estrôncio dopada com cromo, que a presença da fase secundária (SrFe2O5) diminui com o aumento da adição de cromo, e que a proporção de x = 0,4 de cromo favoreceu o aumento da magnetização de saturação.

Chromium-doped strontium hexaferrite powder was prepared by combustion reaction. The influence of the Cr3+ concentration on the SrCr xFe12-xO19 system was investigated. The powder was prepared according to the concept of propellant chemistry and heated on a conventional plate. The resulting material was characterized by X-ray diffraction, scanning electron microscopy and magnetic measurements. The results indicate that chromium-doped hexaferrite nanopowders were obtained successfully. The presence of the secondary phase (SrFe2O5) tended to decrease with increasing chromium content and the ratio of x = 0.4 of chromium enhanced the material's saturation magnetization.

Drying is a single operation employed to prolong the life of a large quantity of vegetables. Carrot (Daucus carota) drying has been the subject of many studies. This plant has been highlighted in the human diet for having high nutritional value, mainly due to the high content of β-carotene. In this work, carrot drying behavior was studied in a regular microwave dryer and a vacuum microwave dryer. A vacuum of 450 mmHg was applied for drying of carrot in different geometrical shapes (cubes, discs and sticks). The samples were dried at power ratings of 1.0 W/g, 1.5 W/g and 2.0 W/g for both methods of drying. The evolution of physical properties such as density, volume and porosity was monitored and related to the moisture content of the sample and to the method of drying and power rating used. The geometric shape of the sample influenced the drying kinetics and it was verified that the cubic form was responsible for a slower drying. The application of vacuum showed no major changes in the drying kinetics in microwave but influenced the physical properties of the material. The influence of power ratings on the content of β-carotene was also evaluated and discussed. The main difference observed was the lower shrinkage of the samples dried in the vacuum microwave compared to those dried only in microwave.

O objetivo deste trabalho foi a obtenção de ferritas de bário tipo W com estequiometria BaCo2-xNi xFe16O27 por meio do método cerâmico tradicional, que é muito difundindo nas indústrias de processamento cerâmico por ser econômico e de relativa facilidade na obtenção de pós-cerâmicos. Materiais aditivados podem afetar as propriedades elétricas, magnéticas e a microestrutura das ferritas por diferentes mecanismos. Assim, temos como objetivo investigar o efeito da substituição dos elementos cobalto e níquel na microestrutura da hexaferrita tipo W com fórmula estequiométrica BaCo2-xNi xFe16O27, x = 0,0, 0,6, 1,0 e 2.

The purpose of this work was to obtain W-type barium ferrites with a BaCo2-xNi xFe16O27 composition using the traditional ceramic method commonly used in the ceramic processing industry because it is a cost-effective and relatively easy route for preparing ceramic powders. Doping materials can affect the electrical, magnetic and microstructural properties of ferrites by different mechanisms. Hence, we examined the effect of substituting the elements cobalt and nickel in the microstructure of W-type hexaferrite with a stoichiometric composition of BaCo2-xNi xFe16O27 with x = 0.0, 0.6, 1.0 and 2.

Este trabalho envolveu a caracterização microestrutural, vibracional e das propriedades dielétricas da hexaferrita de bário obtida pelo método cerâmico. A hexaferrita de bário (BaFe12O19) foi processada por moagem de baixa energia seguida de tratamento térmico. A caracterização estrutural indicou que amostras calcinadas apresentaram a fase desejada. Entretanto, uma fase de impureza (Ba3Fe32O51) foi observada após a moagem.

This work involved a characterization of the structural, microstructural, vibrational and dielectric properties of barium hexaferrite prepared by a ceramic synthesis method. The barium hexaferrite (BaFe12O19) was processed by low energy ball milling following by heat treatment. The structural characterization indicated that the calcined samples contained the desired phase. However, an impurity phase (Ba3Fe32O51) was detected after milling

Metastable-to-stable transformation in oxides is always associated with drastic reduction in surface area and/or porosity. Therefore, all earlier efforts to stabilize the pore structure of oxides undergoing a metastable-to-stable phase transformation are interesting for both scientific and technological concerns. This work presents a new experimental technique for catalytic oxide production through sonication in acid solution for attainment of the anatase-rutile transformation. Mesoporous structure of titania and surface area were stabilized in the rutile phase after calcinations at 430 and 730ºC. Analysis by scanning electron microscopy (SEM) and nitrogen isotherms showed that the mesoporous structure was preserved after calcinations. After the sonication of titania for 32 hours, rutile phase was obtained at 730ºC and still kept a surface area of 28m²/g. When sonicated for 64 h, rutile was obtained at 430ºC, still preserving an area of 52m²/g.

Single-photon emission computed tomography (SPECT) is a non-invasive imaging technique, which provides information reporting the functional states of tissues. SPECT imaging has been used as a diagnostic tool in several human disorders and can be used in animal models of diseases for physiopathological, genomic and drug discovery studies. However, most of the experimental models used in research involve rodents, which are at least one order of magnitude smaller in linear dimensions than man. Consequently, images of targets obtained with conventional gamma-cameras and collimators have poor spatial resolution and statistical quality. We review the methodological approaches developed in recent years in order to obtain images of small targets with good spatial resolution and sensitivity. Multipinhole, coded mask- and slit-based collimators are presented as alternative approaches to improve image quality. In combination with appropriate decoding algorithms, these collimators permit a significant reduction of the time needed to register the projections used to make 3-D representations of the volumetric distribution of target’s radiotracers. Simultaneously, they can be used to minimize artifacts and blurring arising when single pinhole collimators are used. Representation images are presented, which illustrate the use of these collimators. We also comment on the use of coded masks to attain tomographic resolution with a single projection, as discussed by some investigators since their introduction to obtain near-field images. We conclude this review by showing that the use of appropriate hardware and software tools adapted to conventional gamma-cameras can be of great help in obtaining relevant functional information in experiments using small animals.

This work is related to removal of phenol from wastewaters by adsorption onto polymeric resins, a current alternative to activated carbon. A closed circuit, bench-scale liquid fluidized bed system was developed for this purpose. Phenol aqueous solutions with initial concentrations in the range of 0.084 to 0.451 kg/m³ were used to fluidize small permeable capsules of stainless steel screen containing a commercial resin at 308 K. Experiments were carried out using a fluidizing velocity 20% above that of the minimum fluidization of the capsules. Typically, 30 passages of the liquid volume circulating through the bed were required to reach a quasi-equilibrium concentration of phenol in the treated effluent. A simple batch adsorption model using the Freundlich isotherm successfully predicted final phenol concentrations. Suspended solids, often present in residual waters and a common cause of fixed bed clogging, were simulated with wood sawdust.

As hexaferritas de bário são óxidos ferrimagnéticos hexagonais que atraem grandes interesses científicos, tecnológicos e industriais como uso de magneto permanente. A hexaferrita de bário usada neste trabalho foi preparada usando um processo de moagem de alta energia seguido de tratamento térmico. Imagens do comportamento magnético foram estudadas utilizando-se microscopia de força magnética, com campo magnético externo aplicado progressivamente, onde se observa que os domínios magnéticos tornam-se mais intensos e definidos com o aumento da intensidade do campo magnético aplicado.

The structure of magnetic domains in barium hexaferrite was investigated using magnetic force microscopy through the application of an external magnetic field. The material was obtained by sintering of powders processed by high-energy milling. The surface magnetic domains structures were determined using magnetic force microscopy and it was observed that increasing the applied magnetic field, the domains became more intense and defined, showing sizes around 2.9 µm, when a magnetic field of 8.40 kOe was applied.

Group contribution methods have been widely used for the estimation and prediction of properties of a great variety of chemical compounds and mixtures of compounds. In this paper, the glass transition temperature of polymers is evaluated by a second-order group contribution method previously developed by Ourique and Silva Telles (1997). From a total of 1018 polymers in the data base, 923 are selected as the training set to which group and interacting group contributions are assigned. The remaining 95 polymers are used as the validation set. Results are compared to the ones obtained by application method of Van Krevelen method's to the same data base.

In operations using spouted beds, it is of major importance, from an energy consumption point of view, to operate the process as close as possible to the minimum spout flow. At this point, the speed of the gas (for example, warm air in drying operations) is greater than the amount of heat and mass transfer involved, although it only transfers the minimum amount of momentum to maintain the spout. Therefore, by staying close to this minimum flow condition, it is possible to perform a stable operation and to obtain energy savings not only in the heating of the gas but also in its displacement by blowers. In order to improve the operation of such processes, a study is carried out by implementing a simple optimizing control structure on a spouted bed experimental set-up. The air flow is regulated by a frequency inverter, at the speed of blower rotation. A PI controller was used and the set-point for the air flow rate is calculated on-line by a simple and well-known minimization method called Golden Section Search. This set-point is constantly updated with values very close to the actual minimum spout flow rate. To accomplish the calculations and data acquisitions, a microcomputer with an interface and an analog signal conditioner is used .

Sinopse Na Amazônia se encontram algumas espécies de Galyptranthes (Myrtaceae). A comparação do óleo essencial de suas folhas varia de espécie para espécie. Assim é que o óleo destilado de C. spruceana Berg (rendimento de 1,7%) contém os terpenos α - pineno (5,8%), β - pineno (8,1%), limoneno (54,6%), um álcool monoterpênico (1,2%), neral (2,0%), geranial (3,2%) e perilaldeido (25,0%); enquanto o óleo destilado de uma espécie de Calyptranthes não identificada (rendimento 2,2%), contém metilchavicol de alilbenzeno (98,7%).

Summary Several arboreous Calyptranthes (Myrtaceae) species occur in Amazonia. The composition of the essential oil of their leaves varies widely from species to species. Thus, the oil distilled from C. spruceana Berg (Yield 1,7%) contains the terpenes α pinene (5,8%), β- pinene (8,1%), limonene (54,6%), a monoterpenic alcohol (1,2%), neral (2,0%), geranial (3,2%) and perillaldehyde (25,0%); while the oil distilled from an unidentified Calyptranthes species (yield 2,2%) contains the allylbenzene methylchavicol (98,7%)

Sinopse Como parte de um estudo químico de plantas brasileiras, comunica-se a presença de óleos essenciais na madeira de Dicypellium caryophyllatum Nees (Lauraceae), de composição: eugenol 95,5% O-metileugenol 1,6%; as fôlhas de Myrcia polyantha D.C., var. coriácea Bg. (Myrtaceae), com um rendimento de 2%, de composição: limoneno 4,5%, nera 128,0%, geranial 40,2%, sesquiterpenos 14,6%; a casca de Parkia oppositifolia Spr. ex Benth. (Leguminose-mimoeoidaeae), de composição: salicilato de metila 98,2%; a madeira do tronco de Dalbergia decipuiaris Rizz. et Mattos (Leguminosae-Papilionatae), de composição: nerolidol 97,2%; a madeira do tronco de Poecilanthe parviflora Benth. (Leguminosae-Papilionatae): nerolidol 26,0%; as fôlhas de Piper cavalcantei Yuncker (Piperaceae), rendimento 1,9% de composição: safrol 69,0%, metileugenol 8,0%, terpenos 23,0%.

Summary As part of a chemical survey of brazilian plants, we report the presence of essential oils in the wood of Dicypellium caryophyllatum Nees (Lauraceae), composition: eugenol 95,5%, O-methyleugenol 1,6%; the leaves of Myrcia polyantha D.C., var. coriacea Bg. (Myrtaceae), yield: 2%, composition: limonene 4,5%, neral 28,0%, geranial 50,2%, sesquiterpenes 14,6%; the bark of Parkia oppositifolia Spr. ex Benth. (Leguminosae-Mimosoideae). composition: methyl salicylate 98,2%; the trunk wood of Dalbergia decipularis Rizz. et Mattos (Leguminosae-Papilionatae), composition: nerolidol 97,2%; the trunk wood of Poecilanthe parviflora Benth. (Leguminosae-Papilionatae), composition: nerolidol 26,0%; the leaves of Piper cavalcautei Yuncker (Piperaceae), yield: 1.9%, composition: safrol 69,0% methyleugenol 8,0% terpenes 23,0%.