O azul do céu e o vermelho do pôr-do-sol

Este trabalho expõe uma dedução da intensidade da luz espalhada por pequenas partículas na atmosfera, o que explica o porquê do azul do céu e o vermelho do pôr-do-sol. Mostramos, também, uma experiência bem simples, sobre os temas abordados, que foi elaborada com o intuito de aplicar a alunos do Ensino Médio

Transpressive dextral shear in the Italva-Itaperuna section, Northern State of Rio de Janeiro, Brazil

Structural analysis carried out on a segment of the Neoproterozoic Ribeira Belt, southeastern Brazil, show that it represents part of the transpressive dextral orogen related to the Central Mantiqueira Province. NNE-trending and steeply dipping regional mylonitic belts form anastomosed geometry, and describe a map-scale, S-C-like structure that is characterized by their deflection towards NE near the Além Paraíba Lineament. Lithological and structural control related to deformation partition were responsible for the formation of felsic mylonitic granulites with S-type granites lenses developed in ductile shear zones, alternated with less deformed intermediate to basic granulites associated with charnockites. The dextral shear sense indicators are consistent with transpressive deformation in the region and are common especially at the border of the main shear zones. The presence of S-type leucogranite may lead to variations of linear and planar relationships, which result in local extension zones. These elements are consistent with oblique continental collision considering the São Francisco Craton as a stable block.

Development of instrumentation for amperometric and coulometric detection using ultramicroelectrodes

In this work it is presented the development of a simple, portable and inexpensive instrumentation for amperometric and coulometric detection in different analytical instrumentation systems utilizing ultramicroelectrodes. The software, developed in LabVIEW 7.1TM, is capable to carry out three main detection techniques (amperometric, pulsed amperometric and coulometric detection) and a voltammetric technique (cyclic voltammetry). The instrumentation was successfully evaluated using the following systems: cyclic voltammograms of metallic electrodes in alkaline solutions, flow electrochemical detection of glucose and glycine and direct determination of herbicide glyphosate (electrochemical detection coupled to HPLC).

Design, construction and evaluation of a simple pressurized solvent extraction system

This work describes the construction and testing of a simple pressurized solvent extraction (PSE) system. A mixture of acetone:water (80:20), 80 ºC and 103.5 bar, was used to extract two herbicides (Diuron and Bromacil) from a sample of polluted soil, followed by identification and quantification by high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). The system was also used to extract soybean oil (70 ºC and 69 bar) using pentane. The extracted oil was weighed and characterized through the fatty acid methyl ester analysis (myristic (< 0.3%), palmitic (16.3%), stearic (2.8%), oleic (24.5%), linoleic (46.3%), linolenic (9.6%), araquidic (0.3%), gadoleic (< 0.3%), and behenic (0.3%) acids) using high-resolution gas chromatography with flame ionization detection (HRGC-FID). PSE results were compared with those obtained using classical procedures: Soxhlet extraction for the soybean oil and solid-liquid extraction followed by solid-phase extraction (SLE-SPE) for the herbicides. The results showed: 21.25 ± 0.36% (m/m) of oil in the soybeans using the PSE system and 21.55 ± 0.65% (m/m) using the soxhlet extraction system; extraction efficiency (recovery) of herbicides Diuron and Bromacil of 88.7 ± 4.5% and 106.6 ± 8.1%, respectively, using the PSE system, and 96.8 ± 1.0% and 94.2 ± 3.9%, respectively, with the SLP-SPE system; limit of detection (LOD) and limit of quantification (LOQ) for Diuron of 0.012 mg kg-1 and 0.040 mg kg-1, respectively; LOD and LOQ for Bromacil of 0.025 mg kg-1 and 0.083 mg kg-1, respectively. The linearity used ranged from 0.04 to 1.50 mg L-1 for Diuron and from 0.08 to 1.50 mg L-1 for Bromacil. In conclusion, using the PSE system, due to high pressure and temperature, it is possible to make efficient, fast extractions with reduced solvent consumption in an inert atmosphere, which prevents sample and analyte decomposition.

Determinação de minoxidil em formulações farmacêuticas usando permanganometria

Um método clássico para a determinação de minoxidil em formulações farmacêuticas é proposto baseado na reação redox entre KMnO4 e o minoxidil. Os melhores resultados na permanganometria foram obtidos usando concentrações de 1,00 x 10-2 mol L-1 para o permanganato. O minoxidil foi usado como titulante na concentração de 2,00 x 10-2 mol L-1 diluído em solução de H2SO4 2,00 mol L-1. As recuperações para método proposto foram da ordem de 94,5 a 95,2 % dependendo da amostra comercial. O método proposto foi aplicado à amostras comerciais contendo minoxidil e comparado com resultados obtidos a partir de procedimentos cromatográficos com erros relativos da ordem de -1 a -5,26%. O procedimento se mostrou simples, rápido e pode ser uma alternativa para a determinação de minoxidil em amostras farmacêuticas, nas quais a concentração do fármaco é relativamente elevada.

Development and validation of a simple and rapid capillary zone electrophoresis method for determination of nnrti nevirapine in pharmaceutical formulations

A simple and fast capillary zone electrophoresis (CZE) method has been developed and validated for quantification of a non-nucleoside reverse transcriptase inhibitor (NNRTI) nevirapine, in pharmaceuticals. The analysis was optimized using 10 mmol L-1 sodium phosphate buffer pH 2.5, +25 kV applied voltage, hydrodynamic injection 0.5 psi for 5 s and direct UV detection at 200 µm. Diazepam (50.0 µg mL-1) was used as internal standard. Under these conditions, nevirapine was analyzed in approximately less than 2.5 min. The analytical curve presented a coefficient of correlation of 0.9994. Limits of detection and quantification were 1.4 µg mL-1 and 4.3 µg mL-1, respectively. Intra- and inter-day precision expressed as relative standard deviations were 1.4% and 1.3%, respectively and the mean recovery was 100.81%. The active pharmaceutical ingredient was subjected to hydrolysis (acid, basic and neutral) and oxidative stress conditions. No interference of degradation products and tablet excipients were observed. This method showed to be rapid, simple, precise, accurate and economical for determination of nevirapine in pharmaceuticals and it is suitable for routine quality control analysis since CE offers benefits in terms of quicker method development and significantly reduced operating costs.

A novel disposable electrochemical microcell: construction and characterization

An alternative technique for the fabrication of disposable electrochemical microcells containing working, reference and auxiliary electrodes on a single device is reported. The procedure is based on thermal-transfer of toner masks onto CD-R (recordable compact discs) gold surfaces to define the layout of the electrodes (contour). In a subsequent step, the layout is manually painted with a permanent marker pen. The unprotected gold surface is conveniently etched (chemical corrosion) and the ink is then easily removed with ethanol, generating gold surfaces without contamination. The final and reproducible area of the electrodes is defined by heat transference of a second toner mask. Silver epoxy is deposited on one of the gold bands which is the satisfactorily used as reference electrode. These microcells were electrochemically characterized by cyclic, linear, and square wave voltammetry, and several electroactive species were used as model systems. The area reproducibility of the electrodes for different microcells was studied and a relative standard deviation better than 1,0% (n = 10) was obtained. Disposable electrochemical microcells were successfully used in analysis of liquid samples with volumes lower than 200 µL and good stability and reproducibility (RSD less than 2.0%) were achieved. These microcells were also evaluated for quantification of paracetamol and dipyrone in pharmaceutical formulations.

Effect of experimental heat treatment on mechanical properties of resin composites

The aim of this study was to verify the influence of an experimental heat treatment (170ºC/10 min) using a casting furnace on the mechanical properties (hardness and flexural strength) of 2 commercial direct resin composites (TPH Spectrum and Filtek P60) compared to a commercial indirect resin system (BelleGlass). Heat treatment temperature was determined after thermal characterization by thermogravimetry (TG) and differential scanning calorimetry (DSC). Data was analyzed by ANOVA and Tukey's test at 5% significance level. There was statistical significance for the main factor heat treatment (p=0.03) and composite (p=0.02), for flexural strength. For Knoop hardness, only the main factor composite was statistically significant (p=0.00). P60 presented higher hardness than TPH. No statistically significant correlation between mechanical properties tested was detected. Based on these results, it was possible to conclude that heat treatment influenced flexural strength of direct composites, while it was not observed for hardness. The association of direct composites with a simple post-cure heat treatment may be an alternative for current indirect composite systems, although more studies are needed to verify other properties of the composites for this application.

Redescription of Hanleya brachyplax (Polyplacophora, Hanleyidae) from the south-southeastern Brazilian coast

Hanleya brachyplax Simone & Jardim in Rios, 2009 is described in detail. The species occurs off the southeastern and south coast of Brazil (São Paulo and Santa Catarina states) in depths from 250 to 408 m. It differs from its congeners in having uniform white valves; wide intermediate valves; the tail valve with straight profile in the antemucronal area, and a concave postmucronal surface; and a cream-colored girdle, covered by non-articulated spines. An anatomical investigation was also performed, showing the main muscle groups; the presence of gills in the posterior third of the pallial groove; auricle with six orifices; a very flat kidney, restricted to the posterior half of the animal; and a simple esophageal region. The odontophore has a single pair of long cartilages. The buccal musculature is also described.

New species of Trachycorystes Bleeker, with comments on other species of the genus (Ostariophysi: Siluriformes: Auchenipteridae)

A new species of Trachycorystes from the rio Aripuanã, above Dardanelos and Andorinhas falls, is described. The new species is distinguished from the only other species of the genus, T. trachycorystes, by the following characteristics: jaws of equal length (vs. lower jaw prognathous in T. trachycorystes); skull roof covered by thick (vs. thin) integument; inner mental barbel very thin and short not reaching base of outer barbel (vs. extending to or beyond base of outer mental barbel); dorsal-fin spine serrated posteriorly, smooth or rough anteriorly (vs. serrated anteriorly and smooth or rough posteriorly); caudal fin shallowly forked (vs. emarginate); and gas bladder simple, without diverticula (vs. with three posterior diverticula). Comments and data on the nominal species Trachycorystes trachycorystes are provided. Trachycorystes cratensis Miranda Ribeiro, 1937, is allocated to the genus Trachelyopterus Valenciennes, 1840, and another local catfish species, Parotocinclus aripuanensis Garavello, 1988, has its type locality reassigned.

New species of thorny catfish, genus Leptodoras Boulenger (Siluriformes: Doradidae), from Tapajós and Xingu basins, Brazil

A new species of thorny catfish (family Doradidae) is described as a member of genus Leptodoras Boulenger by having a modified oral hood and first gill arch with enlarged accessory lamellae extending well onto medial face of gill filaments. The new species is distinguished by three characteristics unique within Leptodoras: gas bladder moderately sized (not reduced) with simple walls (diverticula absent), and paired bony capsules on anteriormost vertebrae reduced to paired cup-like laminar ossifications separated by triangular septum. The new species was discovered from material recently collected in the Tapajós basin at Serra do Cachimbo and in the headwaters of rio Xingu. The species description is supplemented by a detailed osteological description, discussion on its placement among congeners, and a re-evaluation of the diagnosis of Leptodoras and its relationships with sister taxon Anduzedoras oxyrhynchus. In addition, the distributions of several species of Leptodoras are expanded based on recent collecting efforts and identification of museum specimens not previously studied.

Aleitamento materno, alimentação complementar, sobrepeso e obesidade em pré-escolares

OBJETIVO: Analisar a associação do sobrepeso e da obesidade com o aleitamento materno e a alimentação complementar em pré-escolares. MÉTODOS: Estudo transversal envolvendo 566 crianças matriculadas em escolas particulares no município de São Paulo, SP, 2004-2005. A variável dependente foi sobrepeso e obesidade. Para a classificação do estado nutricional das crianças foram utilizadas as curvas de percentis do Índice de Massa Corporal para idade, classificando como sobrepeso valores e"P85 e simples e regressão logística múltipla com modelo hierarquizado. RESULTADOS: A prevalência de sobrepeso e obesidade da população estudada foi de 34,4%. Foram fatores de proteção contra sobrepeso e obesidade o aleitamento materno exclusivo por seis meses ou mais (IC 95% [0,38;0,86]; OR=0,57; p=0,02) e o aleitamento materno por mais de 24 meses (IC 95% [0,05;0,37]; OR=0,13; p=0,00). CONCLUSÕES: Os resultados sugerem que o aleitamento materno pode proteger as crianças contra o sobrepeso e a obesidade, agregando mais uma vantagem ao leite materno.

Presença de mosquitos (Diptera: Culicidae) em piscinões na zona leste de São Paulo

INTRODUÇÃO: Alterações no ambiente vêm contribuindo com mudanças climáticas, como o aumento do volume de chuvas, que acarreta as inundações. Medidas estão sendo tomadas no enfrentamento das inundações, como a implantação dos reservatórios de contenção de cheias (piscinões). Neste trabalho, foi avaliada a fauna de culicídeos, de importância epidemiológica, nos piscinões Caguaçu e Inhumas. MÉTODOS: Foram realizadas coletas mensais nos piscinões Caguaçu e Inhumas, situados na região leste de São Paulo, de março de 2006 a fevereiro de 2007, empregando-se os métodos de concha entomológica e aspirador. Para análise dos dados, foram realizadas análises estatísticas descritivas e a regressão linear simples. RESULTADOS: Foram coletados 8.917 culicídeos, destacando-se Culex (Culex) quinquefasciatus, que representou 98,9% dos espécimes no Inhumas e 95,2% no Caguaçu. No Caguaçu, a maior frequência de imaturos foi observada no vertedouro (61%) e no Inhumas na canaleta (42,6%). A precipitação prediz 87% da abundância numérica de larvas de terceiro e de quarto estágio no Caguaçu e 60% do número de pupas coletadas. No Inhumas, a precipitação explicou 36% da abundância numérica de larvas e 18% do número de pupas. CONCLUSÕES: Culex quinquefasciatus, vetor de agentes da filariose, arboviroses e fator de incômodo à população, foi a espécie mais frequente nos dois ambientes. Medidas de controle da espécie nos piscinões estudados se fazem necessárias tendo em vista seu potencial epidemiológico.

Obesidade na adolescência e seus principais fatores determinantes

O objetivo deste trabalho foi discutir os principais fatores ambientais determinantes do sobrepeso e da obesidade em adolescentes, fundamentando-se em uma revisão crítica sobre o assunto. Para a revisão do tema foram consultadas as principais bases de dados nacionais e internacionais, entre elas, Medline/Pubmed, Web of Science, SciELO, Lilacs, compreendendo o período de 1975 a 2009. Os descritores e termos MeSH utilizados na busca foram: "sobrepeso", "obesidade", "adolescência", "adolescentes", "atividade física", "ingestão alimentar". Os resultados das pesquisas indicam que as mudanças ocorridas nos padrões alimentares nas últimas décadas, como o aumento do consumo de açúcares simples, alimentos industrializados e ingestão insuficiente de frutas e hortaliças, estão diretamente associadas ao ganho de peso dos adolescentes. Além disso, a redução progressiva da prática de atividade física combinada ao maior tempo dedicado às atividades de baixa intensidade, como assistir televisão, usar computador e jogar videogame, também tem contribuído para o aumento de peso dos jovens. Conclui-se, portanto, que as variáveis relacionadas ao padrão alimentar e de atividade física devem ser priorizadas nas intervenções voltadas para a prevenção da obesidade entre adolescentes.

Ocorrências em pronto-socorro: eventos sentinela para o monitoramento da atenção básica de saúde

O estudo tem como ponto de partida a hipótese de que determinadas ocorrências nosológicas atendidas em pronto-socorro, escolhidas com base no conceito de evento sentinela, podem estar relacionadas a falhas da atenção básica e ser utilizadas na formulação de um indicador para o monitoramento desta atenção. Foram utilizados dados quantitativos e qualitativos sobre ocorrências previamente escolhidas e atendidas em pronto-socorro. Usando-se a triangulação de métodos, verificaram-se as diferenças das freqüências dessas ocorrências entre as áreas/unidades básicas de saúde (UBS) de procedência dos pacientes e as motivações determinantes da procura pelo pronto-socorro. As freqüências das ocorrências apresentaram valores de 30% a 42,8% conforme a área/UBS de procedência (Ç2 = 9,19 e p = 0,027). As entrevistas sugeriram a existência de causalidade entre o motivo declarado da procura do pronto-socorro e a atuação das unidades básicas. Conclui-se que: (1) a freqüência das ocorrências escolhidas foi influenciada pelas áreas/UBS de procedência das pessoas; (2) essa influência decorre, em parte, da situação da atenção básica; (3) o instrumental estudado é simples e pode contribuir para o gestor local no acompanhamento cotidiano da situação dos serviços básicos.