Determinação da granulometria e análise das condições operacionais do peneiramento de painço (Panicum miliaceum) / Determination of granulometry and analysis of operational conditions of millet (Panicum miliaceum) sifting

A separação granulométrica visa separar e classificar materiais de acordo com seus diâmetros.  Um método em destaque para a realização dessa separação é o peneiramento. No peneiramento,  alimenta-se  um conjunto de peneiras com uma quantidade de massa predeterminada do material que se deseja separar e classificar. Sob agitação, os particulados tendem a passar ou reter-se nas peneiras conforme seu diâmetro e o diâmetro de abertura das peneiras. Assim, a técnica de peneiramento é muito empregada para realizar a separação e classificação de particulados, além de ser utilizada para construção de modelos de distribuição de materiais. Portanto, o presente estudo objetivou realizar a separação dos grãos de painço em diferentes condições operacionais e determinar um modelo de distribuição granulométrica para as sementes. Avaliando-se o peneiramento, os grãos reteram-se na peneira de 10 Mesh, na qual cerca de 90% dos grãos acumulou-se, indicando tamanhos de partícula entre 2 mm e 2,5 mm. Além disso, o modelo que melhor descreveu o ensaio foi o Gates, Gaudin e Schuhmann (GGS), para uma condição operacional de 5 minutos e intensidade de agitação 9

Réquiem médico. Un pasado acabado: absurdos de la medicina actual

EL LIBRO MUESTRA EXPERIENCIAS SOBRE EL TEMA DE LA PRÁCTICA MEDICA.EL LIBRO ABORDA TEMAS RELACIONADAS CON LA PRACTICA MEDICA, Y LOS DIFERENTES OBSTÁCULOS QUE SE ENCUENTRAN A NIVEL DE LAS INSTITUCIONES PARA OFRECER UNA MEJOR ATENCIÓN A LA POBLACIÓN PARA EL TRATAMIENTO DE LA ENFERMEDAD Y LA SALUDNINGUN

Prosthenhystera obesa (Digenea), parasita de Salminus maxillosus (Characidae) da planície de inundação alto rio Paraná, Brasil: influência do tamanho e do sexo do hospedeiro

A hundred and twenty-six specimens of Salminus maxillosus Valenciennes, 1849, were analyzed. Fishes were collected in the floodplain of the upper Paraná river in lotic environments, represented by the Paraná and the Ivinheima rivers and by the Cortado channel, and a semi-lotic one represented by the Baía river. Capture of hosts was undertaken by gill nets of various mesh sizes. Prior to light microscopy, the specimens were fixed in AFA (alcohol, formalin, acetic acid) under slight coverslip pressure, stained in Mayer’s acid carmalum, dehydrated in an alcohol series, cleared in creosote and mounted in Canada balsam. Prevalence of Prosthenhystera obesa Diesing, 1850 was 14.3% and mean intensity of infection 1.75 (range: 1-3). Prevalence of P. obesa is not correlated with standard length of host, a fact that may indicate homogeneity in behavior of S. maxillosus during part of its development. Infection intensity is directly related with increase in size of host. There was no influence of sex of host on prevalence and infection intensity of P. obesa. This fact may suggest similarity in behavior with regard to feeding habit and habitat of males and females. All parasitized hosts were captured in lotic environmentsForam analisados 126 espécimes de Salminus maxillosus Valenciennes, 1849, coletados na planície de inundação do alto rio Paraná em ambiente lótico, representado pelos rios Paraná, Ivinheima e canal Cortado e semi-lótico, representado pelo rio Baía. Para a captura dos hospedeiros utilizaram-se redes de espera de malhagens variadas. Os parasitas foram comprimidos e fixados em AFA (álcool, formalina, ácido acético), corados em carmalúmen de Mayer, desidratados em sequência alcoólica, clarificados em creosoto e montados em bálsamo do Canadá. Prosthenhystera obesa Diesing, 1850 apresentou prevalência de 14,3% e intensidade média de infecção de 1,75 (amplitude: 1-3). A prevalência de P. obesa não apresentou correlação com o comprimento-padrão do hospedeiro, o que poderia indicar homogeneidade no comportamento de S. maxillosus durante parte de seu desenvolvimento. A intensidade de infecção está diretamente relacionada com o aumento no tamanho do hospedeiro. O sexo dos hospedeiros não influenciou o prevalência e a intensidade de infecção de P. obesa, sugerindo uma semelhança no comportamento em relação ao hábito alimentar e habitat de machos e fêmeas. Todos os hospedeiros parasitados foram capturados em ambiente lótic

<b>Composição e estrutura das infracomunidades endoparasitárias de <em>Gymnotus</em> spp. (Pisces: Gymnotidae) do rio Baía, Mato Grosso do Sul, Brasil</b> - DOI: 10.4025/actascibiolsci.v26i4.1527 <b>Composition and structure of the endoparasite infracommunities of <em>Gymnotus</em> spp. (Pisces: Gymnotidae) of the Baía River, Mato Grosso do Sul, Brazil</b> - DOI: 10.4025/actascibiolsci.v26i4.1527

Foram examinados 111 espécimes do gênero <em>Gymnotus</em>. Os peixes foram capturados em peneiras e redes de espera. Foram registradas dezesseis espécies de helmintos, estando 93,7% delas em fase larval. Ocorreram associações positivas significativas entre vinte pares de espécies de parasitas. Todas elas apresentaram um padrão de distribuição agregada na amostra de hospedeiros. Não houve tendência para dominância entre as espécies de parasitas. Hospedeiros machos e fêmeas não apresentaram diferenças significativas entre as diversidades parasitárias, mas houve influência do sexo dos hospedeiros sobre a prevalência e abundância de infecção de <em>Tylodelphys</em> sp. e <em>Spiroxys</em> sp.. Foi observado correlação positiva significativa entre o comprimento total dos hospedeiros e a prevalência e a abundância de infecção de <em>Nomimoscolex chubbi, Contracaecum</em> sp. 2 e <em>Quadrigyrus machadoi</em>. Houve relação significativa entre a prevalência de <em>Herpetodiplostomum</em> sp. 1, <em>Herpetodiplostomum</em> sp. 3, <em>Neodiplostomum</em> sp. e <em>Tylodelphys</em> sp. e o ciclo reprodutivo dos hospedeiros<br>Parasites of 111 specimens of the <em>Gymnotus</em> genus were analyzed. The fishes were captured in bolters and gill nets. Sixteen parasite species were recorded, being 93.7% of the species found in larval stages. Significant positive association and correlation between abundances of twenty pairs of species occurred. All the analyzed parasite species had a clumped pattern in host sample. No dominance was reported among the parasite species. Diversity of the infracommunities of male and female hosts were not different, but influence of hosts' sex in the prevalence and abundance of <em>Tylodelphys</em> sp. and <em>Spiroxys</em> sp. were observed. Significant positive correlation between hosts' total length and prevalence and abundance of <em>Nomimoscolex chubbi, Contracaecum</em> sp. 2 and <em>Quadrigyrus machadoi</em> was observed. The reproductive cycle of hosts was correlated with the <em>Herpetodiplostomum</em> sp. 1, <em>Herpetodiplostomum</em> sp. 3, <em>Neodiplostomum</em> sp. and <em>Tylodelphys</em> sp. prevalence

Spatial, seasonal and ontogenetic changes in food resource use by a piscivore fish in two Pantanal lagoons, Brazil

We evaluated the factors that affect the food resource use by Plagioscion ternetzi using three approaches: spatial, seasonal, and ontogenetic changes. Fish were sampled between March 2000 and February 2001 and March 2003 and February 2004 in the Sinhá Mariana and Chacororé lagoons, wetlands of the Pantanal Matogrossense. Fish was the predominant food in the diet, but shrimps and insects have been also consumed. The diet of P. ternetzi was significantly different between lagoons, but no difference was detected between dry and flood periods. In Sinhá Mariana lagoon, the diet mainly consisted of Psectrogaster curviventris, in both periods. In the flood period in Chacororé lagoon, fish was the dominant food (especially Astyanax spp., Leporinus spp. and Schizodon borellii), and in dry, shrimp and Eigenmannia spp. The Spearman coefficient indicated no correlation between the abundance of caught fish species and their abundances in the diet of P. ternetzi in Sinhá Mariana lagoon, and a strong negative correlation at Chacororé lagoon, although some very consumed preys were numerically abundant in the environment. Despite the intake of insect and shrimp, P. ternetzi was piscivorous since immature stages. A correlation between each item and the size classes of P. ternetziwas tested by means of Pearson correlation that showed that the changes in the use of resources over ontogenetic development have been represented by increased intake of P. curviventris in Mariana lagoon, and S. borellii at Chacororé lagoon, accompanying the increase in the size of the predator. In this way, the results suggest that several factors can be involved in the use of food resources by P. ternezi, among them the abundance, the size and morphological characteristics of the prey

From nano- to micrometer scale: the role of microwave-assisted acid and alkali pretreatments in the sugarcane biomass structure

Abstract Background To date, great strides have been made in elucidating the role of thermochemical pretreatments in the chemical and structural features of plant cell walls; however, there is no clear picture of the plant recalcitrance and its relationship to deconstruction. Previous studies precluded full answers due to the challenge of multiscale features of plant cell wall organization. Complementing the previous efforts, we undertook a systematic, multiscale, and integrated approach to track the effect of microwave-assisted H2SO4 and NaOH treatments on the hierarchical structure of plants, i.e., from a nano- to micrometer scale. We focused on the investigation of the highly recalcitrant sclerenchyma cell walls from sugarcane bagasse. Results Through atomic force microscopy and X-ray diffraction analyses, remarkable details of the assembly of cellulose microfibrils not previously seen were revealed. Following the H2SO4 treatment, we observed that cellulose microfibrils were almost double the width of the alkali pretreated sample at the temperature of 160 °C. Such enlargement led to a greater contact between cellulose chains, with a subsequent molecule alignment, as indicated by the X-ray diffraction (XRD) results with the conspicuous expansion of the average crystallite size. The delignification process had little effect on the local nanometer-sized arrangement of cellulose molecules. However, the rigidity and parallel alignment of cellulose microfibrils were partially degraded. The XRD analysis also agrees with these findings as evidenced by large momentum transfer vectors (q > 20 nm−1), interpreted as indicators of the long-range order of cell wall components, which were similar for all the studied samples except with application of the NaOH treatment at 160 °C. These changes were followed by the eventual swelling of the fiber cell walls. Conclusions Based on an integrated approach, we presented multidimensional architectural models of cell wall deconstruction resulting from microwave-assisted pretreatments. We provided direct evidence supporting the idea that hemicellulose is the main barrier for the swelling of cellulose microfibrils, whereas lignin adds rigidity to cell walls. Our findings shed light on the design of more efficient strategies, not only for the conversion of biomass to fuels but also for the production of nanocellulose, which has great potential for several applications such as composites, rheology modifiers, and pharmaceuticals

A novel Triclosan Methacrylate-based composite reduces the virulence of Streptococcus mutans biofilm.

The use of antimicrobial monomers, linked to the polymer chain of resin composites, is an interesting approach to circumvent the effects of bacteria on the dental and material surfaces. In addition, it can likely reduce the incidence of recurrent caries lesions. The aim of this study was to evaluate the effects of a novel Triclosan Methacrylate (TM) monomer, which was developed and incorporated into an experimental resin composite, on Streptococcus mutans (S. mutans) biofilms, focusing on the analyses of vicR, gtfD, gtfC, covR, and gbpB gene expression, cell viability and biofilm characteristics. The contact time between TM-composite and S. mutans down-regulated the gbpB and covR and up-regulated the gtfC gene expression, reduced cell viability and significantly decreased parameters of the structure and characteristics of S. mutans biofilm virulence. The presence of Triclosan Methacrylate monomer causes harmful effects at molecular and cellular levels in S. mutans, implying a reduction in the virulence of those microorganisms