Effectiveness of house dust mite acaricide tri-n-butyl tin maleate on carpets, fabrics and mattress foam: a standardization of methodology

The aim of this study was to determine the effectiveness of the acaricide tri-n-butyl tin maleate, industrially applied to samples of carpets, mattress foam, and fabrics used for furniture upholstery, soft toys and shoe uppers. Approximately 100 adult house dust mites of the species Dermatophagoides pteronyssinus were inoculated into a Petri dish containing the sample (a piece of carpet, mattress foam, or fabric), treated with the acaricide, randomly collected. Mite-maintenance culture medium was added on top of each sample. After one, two, three, seven and 30 days of incubation at 25 ºC and 75% relative humidity, each dish was examined using a 40X stereoscopic microscope (40X). One hundred percent acaricide effectiveness was obtained in treated materials by the end of the 30th-day postinoculation period, under optimal conditions for mite maintenance.

Ammonia volatilization and yield components after application of polymer-coated urea to maize

A form of increasing the efficiency of N fertilizer is by coating urea with polymers to reduce ammonia volatilization. The aim of this study was to evaluate the effect of polymer-coated urea on the control of ammonia volatilization, yield and nutritional characteristics of maize. The experiment was carried out during one maize growing cycle in 2009/10 on a Geric Ferralsol, inUberlândia, MG, Brazil. Nitrogen fertilizers were applied as topdressing on the soil surface in the following urea treatments: polymer-coated urea at rates of 45, 67.5 and 90 kg ha-1 N and one control treatment (no N), in randomized blocks with four replications. Nitrogen application had a favorable effect on N concentrations in leaves and grains, Soil Plant Analysis Development (SPAD) chlorophyll meter readings and on grain yield, where as coated urea had no effect on the volatilization rates, SPAD readings and N leaf and grain concentration, nor on grain yield in comparison to conventional fertilization.

Foam-forming properties of Ilex paraguariensis (mate) saponin: foamability and foam lifetime analysis by Weibull equation

Saponins are natural soaplike foam-forming compounds widely used in foods, cosmetic and pharmaceutical preparations. In this work foamability and foam lifetime of foams obtained from Ilex paraguariensis unripe fruits were analyzed. Polysorbate 80 and sodium dodecyl sulfate were used as reference surfactants. Aiming a better data understanding a linearized 4-parameters Weibull function was proposed. The mate hydroethanolic extract (ME) and a mate saponin enriched fraction (MSF) afforded foamability and foam lifetime comparable to the synthetic surfactants. The linearization of the Weibull equation allowed the statistical comparison of foam decay curves, improving former mathematical approaches.

In situ synthesis of nanoclay filled polyethylene using polymer supported metallocene catalyst system

In situ ethylene polymerizations were performed using bis(cyclopentadiene)titanium dichloride supported on polyethersulfone as catalyst. The bis(cyclopentadiene)titanium dichloride supported on polyethersulfone catalyst activity estimated by ethylene polymerization was 360 kgPE/molTi/h. During polymerization the fillers used were montmorillionite nanoclays having surface modifications with 35-45 wt% dimethyl dialkyl(14-18)amine (FA) and 25-30 wt% trimethyl stearyl ammonium (FB). These fillers were pretreated with methylaluminoxine (MAO; cocatalyst) for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nanofiller did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nanoclay FB filled polyethylene has higher thermal stability than nanoclay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 ºC, which corresponds to that synthesized by the polyether sulfone supported catalyst.

Water absorbent polymer in sugarcane crop

The water absorbent polymer effect on vegetative growth and production of Theoretical Recovery Sugar (TRS) of sugarcane cv. RB 86 7515 was evaluated on two field tests installed in randomized blocks, with four treatments and five repetitions. The polymer doses were 0; 4; 8 and 12 g m-1 of furrow (test 1) and 0; 1.4; 2.8 and 4.2 g m-1 of furrow (test 2). Test 1 (dec/2007 to may/2009) was implanted in a Distroferric Red Argisol soil in Presidente Prudente - State of São Paulo (SP), Brazil; and the test 2 (Aug/2008 to Aug/2009) was implanted in a Red Yellow Argisol soil in Lucélia - State of São Paulo (SP), Brazil. In test 2, there were no significant differences for any evaluated parameters. In both tests the polymer doses equal to or less than 4 g m-1 of furrow showed no significant effect on the evaluated parameters. In test 1, the polymer doses of 8 and 12 g m-1 of the conditioning polymer increased the number of tillers in stage II of development and led to the largest amount of straw. The gross income per hectare has positive relation with the polymer doses. The polymer had no significant effect on the sugarcane stems productivity and technological parameters.

Estudos histológico, histoquímico e ultra-estrutural de fígados e linfonodos de bovinos com presença de macrófagos espumosos ("foam cells")

Foram examinadas amostras de fígado, rins, baço e linfonodos hepáticos, mesentéricos, retro-mandibulares, pré-escapulares e mediastínicos de 12 lotes em um total de 120 animais, envolvendo diferentes faixas etárias, todos oriundos do Estado de Mato Grosso. Os animais haviam sido mantidos em pastos onde Brachiaria decumbens e Brachiaria brizantha eram as forrageiras predominantes. Macroscopicamente o fígado desses animais mostrava coloração amarelada, mais evidente após 24 horas de fixação em formol a 10%. Nos linfonodos hepáticos e mesentéricos foram evidenciadas, na superfície de corte, estriações esbranquiçadas de forma radiada na cortical e medular com pequenas áreas brancas nodulares multifocais principalmente na medular. Em muitos casos, associado com essas áreas foram vistos focos de aspecto hemorrágico. Microscopicamente foram encontradas, no fígado, linfonodos hepáticos e mesentéricos, células com citoplasma espumoso, muitas das quais multinucleadas. Nos linfonodos hepáticos e mesentéricos estes infiltrados estavam associados a áreas de necrose e hemorragia. No fígado, as células de citoplasma espumoso estavam presentes em todo parênquima, de forma irregular, geralmente formando nódulos ao redor da veia centrolobular. Estas células não se coravam pelo ácido periódico de Schiff (PAS) e apenas fracamente na coloração de gordura pelo Oil Red O. Na ultra-estrutura as células de citoplasma espumoso apresentavam fendas, parcial ou totalmente delimitadas por membrana, que representam a imagem negativa de cristais, presentes também no citoplasma dos hepatócitos.

Relação entre macrófagos espumosos ("foam cells") no fígado de bovinos e ingestão de Brachiaria spp no Brasil

Com o objetivo de estabelecer uma relação etiológica e caracterizar, cronologicamente, o aparecimento de macrófagos espumosos (foam cells), comuns em fígados de bovinos oriundos das regiões de clima tropical do Brasil, foram reexaminados cortes histológicos de fígado de bovinos dos arquivos do Setor de Anatomia Patológica da Embrapa-Projeto Sanidade Animal, RJ. O material utilizado provinha de investigações sobre causas de mortandades em bovinos nas regiões Norte, Centro-Oeste e Sudeste do Brasil, realizadas de 1970 a 1991. Foram estudados 55 fígados de bovinos afetados por enfermidades variadas. Somente foram usados casos em que o tipo de pastagem era conhecido. Essa alteração não foi encontrada de 1970 até o final de 1975, embora 40 amostras (72,7%) tenham sido coletadas nesse período. A presença de macrófagos espumosos, observada a partir de 1976, coincidiu com a introdução da gramínea Brachiaria decumbens var. australiana no Brasil. Algumas amostras eram provenientes de bovinos que apresentaram histórico de fotossensibilização, na época atribuída ao fungo Pithomyces chartarum. Os achados indicam que essas alterações hepáticas são relacionadas com a ingestão de Brachiaria spp.

Effect of particle morphology on the mechanical and thermo-mechanical behavior of polymer composites

Fiber reinforced polymer composites have been used in many applications, such as in automobile, aerospace and naval industries, due basically to their high strength-to-weight and modulus-to-weight, among other properties. Even though particles are usually not able to lead to the level of reinforcement of fibers, particle reinforced polymer composites have been proposed for many new applications due to their low cost, easy fabrication and isotropic properties. In this work, polymer composites were prepared by incorporating glass particles of different morphologies on poly(aryl sulfones) matrices. Particles with aspect ratios equal to 1, 2.5 and 10 were used. The prepared composites were characterized using electron microscopy and thermal analysis. Mechanical properties of the composites were evaluated using a four-point bending test. The thermo-mechanical behavior of the obtained composites was also investigated. The results showed that the morphology of the particles alter significantly the mechanical properties of composites. Particles with larger values of aspect ratio led to large elastic modulus but low levels of strain at failure. This result was explained by modeling the thermo-mechanical behavior of the composites using a viscoelastic model. Parameters of the model, obtained from a Cole-Cole type of plot, demonstrated that interactions at the polymer-reinforcing agent interface were higher for composites with large aspect ratio particles. Higher levels of interactions at interfaces can lead to higher degrees of stress transfer and, consequently, to composites with large elastic modulus, as experimentally observed.

Differences in pressure and temperature transitions of proteins and polymer gels

Pressure-driven and temperature-driven transitions of two thermoresponsive polymers, poly(N-isopropylacrylamide) (pNIPAM) and poly(N-vinylisobutyramide) (pNVIBA)), in both a soluble linear polymer form and a cross-linked hydro-gel form, were examined by a dynamic light-scattering method and direct microscopic observation, respectively. Their behavior was compared with that of protein systems. Changes in some characteristic parameters in the time-intensity correlation functions of dynamic light-scattering measurement of aqueous solutions of pNIPAM at various pressures and temperatures showed no essential differences during temperature and pressure scanning and, as a whole, the motions of polymers in aqueous solutions were similar in two types of transitions until chain shrinkage occurred. The gels (cross-linked polymer gels) prepared from the thermoresponsive polymers also showed similar volume transitions responding to the pressure and temperature increase. In temperature transitions, however, gels showed drastic volume shrinkage with loss of transparency, while pressure-induced transition showed a slow recovery of transparency while keeping the size, after first transient drastic volume shrinkage with loss of transparency. At a temperature slightly higher than the transition under atmospheric temperature, so-called reentry of the volume change and recovery of the transparency were observed during the pressure-increasing process, which implies much smaller aggregation or non-aggregated collapsed polymer chains in the gel at higher pressures, indicating a certain mechanistic difference of the dehydration processes induced by temperature and pressure.

DESIDRATAÇÃO DA POLPA DE ACEROLA (Malpighia emarginata D.C.) PELO PROCESSO "FOAM-MAT"

Foi elaborado um suplemento alimentar em pó, a partir da desidratação da polpa de frutos de acerola utilizando o método "FOAM-MAT". Vários testes utilizando diferentes agentes químicos, que favorecem à formação da espuma, foram realizados, tendo sido escolhido o experimento que mais se ajustou ao parâmetro de densidade recomendado como ideal (0,1 a 0,6). Na condição experimental definida, a polpa foi formulada e desidratrada em estufa de secagem com circulação de ar, a uma temperatura de 60 a 70°C, por 90 minutos, obtendo-se um produto em pó, com umidade final de 7,2%. Em paralelo ao experimento, foi efetuada uma caracterização química da polpa de acerola. O produto em pó obtido, foi embalado em sacos metalizados de 25 gramas e submetido a um estudo de estabilidade por 3 meses. Os resultados encontrados, mostraram que o produto elaborado apresentou elevado teor de vitamina C, em um nível 10 vezes maior do que na polpa integral.