Photometric procedure for quantitative analysis of Aflatoxin B1 in peanuts by thin-layer chromatography using charge coupled device detector

A photometric procedure was developed for determination of aflatoxin B1 in peanuts by TLC-CCD technique. The quantification and detection limit were 1.2 μg kg-1 and 0.4 ng per spot, respectively, with mean recovery of 98%. The CCD camera is sufficiently sensitive to detect small changes in spots fluorescence intensity and the results for performance confirmed the efficiency of the method. Another important property of CCD detector is its linearity for a wide range of luminous stimulus determined by analysis of five-point calibration curves using the intensity of AFB1 fluorescence versus AFB1 concentration (0.8 to 4.8 ng per spot). The method was applied to the analysis of thirty nine peanut samples and aflatoxin B1 levels ranged from 16 to 115 μg kg-1. The TLC-CCD and the photometric procedure developed in this study demonstrated to be a simple and efficient tool for quantitative analyses of AFB1 in peanut samples.

Low metal loading catalysts used for the selective hydrogenation of styrene

A series of Group VIII metal catalysts was obtained for the semi-hydrogenation of styrene. Catalysts were characterized by Hydrogen Chemisorption, TPR and XPS. Palladium, rhodium and platinum low metal loading prepared catalysts presented high activity and selectivity (ca. 98%) during the semi-hydrogenation of styrene, being palladium the most active catalyst. The ruthenium catalyst also presented high selectivity (ca. 98%), but the lowest activity. For the palladium catalyst, the influence of the precursor salt and of the reduction temperature on the activity and selectivity were studied. The following activity series was obtained: PdN-423 > PdCl-673 > PdCl-373> PtCl-673 > RhCl-673 >> RuCl-673. As determined by XPS, differences in activity could be attributed, at least in part, to electronic effects.

Influence of ni addition to a low-loaded palladium catalyst on the selective hydrogenation of 1-heptyne

Semi-hydrogenation of alkynes has industrial and academic relevance on a large scale. To increase the activity, selectivity and lifetime of monometallic catalysts, the development of bimetallic catalysts has been investigated. 1-Heptyne hydrogenation over low-loaded Pd and Ni monometallic and PdNi bimetallic catalysts was studied in liquid phase at mild conditions. XPS results suggest that nickel addition to Pd modifies the electronic state of palladium as nickel loading is increased. Low-loaded Pd catalysts showed the highest selectivities (> 95%). The most active prepared catalyst, PdNi(1%), was more selective than the Lindlar catalyst.

Activity and sulfur resistance of Rh(I) and Pd(II) complexes

Two complexes of Rh(I) and Pd(II) with chloride and tridecylamine ligands were obtained and characterized by Elementary Analysis and by XPS and FTIR spectroscopies. Complexes anchored on γ-Al2O3 were tested in the styrene semi-hydrogenation reaction carried out in the absence or presence of a sulfur poison. Although both low loaded catalysts were highly selective, the Pd(II) complex was three times more active than the Rh(I) complex. The rhodium complex was more sulfur resistant but less active than the palladium complex. Differences in conversion and sulfur resistance between both complexes could be related to electronic and/or geometric effects.

Perfil dos bolsistas PQ da área de Química baseado na Plataforma Lattes

The Lattes Platform, an information system maintained by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), is the main source of information on Brazilian researchers. This paper presents a scientific output profile of the CNPq Productivity Research Fellows in the Chemistry area based on the information extracted automatically from Lattes curricula in the 2002-2011 period using the language "LattesMiner". This paper also provides a comparison with the results of Santos et al. (2010). The findings confirmed that the majority of the researchers are male (67.9%), classified as category 2 (63.2%) and working in the Southeast region (60.7%).

NANOPARTICLES OF TUNGSTEN AS LOW-COST MONOMETALLIC CATALYST FOR SELECTIVE HYDROGENATION OF 3-HEXYNE

Low-cost tungsten monometallic catalysts containing variable amounts of metal (4.5, 7.1 and 8.5%W) were prepared by impregnating alumina with ammonium metatungstate as an inexpensive precursor. The catalysts were characterized using ICP, XPS, XRD, TPR and hydrogen chemisorption. These techniques revealed mainly WO3-Al2O3 (W6+) species on the surface. The effects of the content of W nanoparticles and reaction temperature on activity and selectivity for the partial hydrogenation of 3-hexyne, a non-terminal alkyne, were assessed under moderate conditions of temperature and pressure. The monometallic catalysts prepared were found to be active and stereoselective for the production of (Z )-3-hexene, had the following order: 7.1WN/A > 8.5 WN/A ≥ 4.5 WN/A. Additionally, the performance of the synthesized xWN/A catalysts exhibited high sensitivity to temperature variation. In all cases, the maximum 3-hexyne total conversion and selectivity was achieved at 323 K. The performance of the catalysts was considered to be a consequence of two phenomena: a) the electronic effects, related to the high charge of W (+6), causing an intensive dipole moment in the hydrogen molecule (van der Waals forces) and leading to heterolytic bond rupture; the H+ and H- species generated approach a 3-hexyne adsorbate molecule and cause heterolytic rupture of the C≡C bond into C- = C+; and b) steric effects related to the high concentration of WO3 on 8.5WN/A that block the Al2O3 support. Catalyst deactivation was detected, starting at about 50 min of reaction time. Electrodeficient W6+ species are responsible for the formation of green oil at the surface level, blocking pores and active sites of the catalyst, particularly at low reaction temperatures (293 and 303 K). The resulting best catalyst, 7.1WN/A, has low fabrication cost and high selectivity for (Z )-3-hexene (94%) at 323 K. This selectivity is comparable to that of the classical and more expensive industrial Lindlar catalyst (5 wt% Pd). The alumina supported tungsten catalysts are low-cost potential replacements for the Lindlar industrial catalyst. These catalysts could also be used for preparing bimetallic W-Pd catalysts for selective hydrogenation of terminal and non-terminal alkynes.

Mycoplasma suis in naturally infected pigs: an ultrastructural and morphometric study

Swine eperythrozoonosis is a haemotrophic disease caused by Eperythrozoon suis, actually called Mycoplasma suis, an extracellular bacterial organism that apparently adheres to pig erythrocyte membrane, inducing its deformation and damage. Since little is known about the ultrastructural and morphometrical aspects of this microorganism, the present work aimed to deal with these issues. The ultrastructural study revealed the presence of structures corresponding to tubules disseminated throughout the soma of M. suis. A variable separation between the microorganism membrane and that of the erythrocyte was also observed. The structural and positional attitude of M. suis could allow speculation about its mechanism of action.

Bone changes caused by experimental Solanum malacoxylon poisoning in rabbits

The aim of this study was to describe the bone changes observed after a daily oral administration of the calcinogenic plant Solanum malacoxylon (syn. S. glaucophyllum) (Sm) during 9 days. The Sm-poisoned rabbits had an increase of bone resorption in the endosteal surface of the cortical zone and also in the surface covered by osteoblasts of the primary and secondary spongiosa of the trabecular bone compartment. Moreover, the epiphyseal growth plates in long bones appeared narrower than in the control rabbits, with reduction of the proliferative and hyperthrophic chondrocyte zones. The electron microscopic study revealed a significant decrease of proteoglycans in the hyperthrophic chondrocyte zone evidenced by a significant reduction of rutenium red positive granules in the poisoned rabbit. Altogether, these data suggest that cell differentiation may play a pivotal role in the pathogenesis of Sm-induced bone lesions.

Detecção do Grupo Mycoplasma mycoides por imunoperoxidase indireta (IPI) e PCR-REA em conduto auditivo de bovinos

O Grupo Mycoplasma mycoides (GMM) foi diagnosticado por PCR-REA e imunoperoxidase indireta (IPI) em amostras de lavados de conduto auditivo de bovinos no Estado do Rio de Janeiro, Brasil. 60 bovinos foram selecionados aleatoriamente. As lavagens foram feitas com uso de seringas estéreis contendo um volume de 60 mL de solução salina tamponada (PBS pH 7.2). As amostras obtidas foram estocadas em glicerol (1:2) e congeladas a 20ºC até uso. Estas amostras foram diluídas até 10-5 e repicadas em meio Hayflick modificado, sólido e líquido, sendo incubados a 37ºC por 48-72 horas. As placas foram mantidas em microaerofilia e observadas diariamente, para visualização das colônias típicas em “ovo-frito”. Das 60 amostras cultivadas, 48 (80,00%) foram positivas para Mycoplasma spp. A prevalência obtida para o GMM na IPI foi de 20,0% (12/60) enquanto na PCR-REA foi de 41,7% (25/60). Das cepas tipificadas pela IPI 58,3% (7/12) foram M. mycoides subsp. mycoides LC e 41,7% (5/12) foram M. capricolum. Na PCR-REA o grupo M. mycoides foi confirmado pela visualização de um amplicon de 785bp, compatível com este grupo. O valor encontrado no teste Kappa para associação entre estes testes foi de 0,14 (P>0,05. Na clivagem do produto da PCR com a enzima de restrição AluI, de cepas de referências e dos isolados de ouvido os fragmentos obtidos foram de 81, 98, 186 e 236pb, mas não de 370pb, que é específica para o agente da Pleuropneumonia Contagiosa Bovina. A presença de espécies de micoplasmas no conduto auditivo de bovinos assintomáticos representa um risco para propagação de Mycoplasma spp. entre rebanhos bovinos no Brasil.

Patterns of parasitism by Amblyomma rotundatum (Ixodidae) on Rhinella schneideri (Bufonidae) in islands of São Francisco River, Minas Gerais, Brazil

Abstract: We sampled ticks from specimens of the rococo toad Rhinella schneideriby flannel dragging on two Islands located in the São Francisco River near the Três Marias hydroelectric dam, southeastern Brazil. A total of 120 toads was examined, of which 63 (52.5%) were parasitized only by Amblyomma rotundatumtotaling 96 larvae, 163 nymphs and 134 females. The burden of parasitism ranged from one to 43 ticks, with a mean intensity of infestation of 6.2±5.5 ticks per host. The tick A. rotundatumexhibited highly aggregated distribution. Peak abundance of larvae and nymphs occurred in the dry season (May to September), whereas peak abundance of females occurred in the wet season (October to April). We collected most ticks near the head and hind limbs of R. schneideri. The finding of two engorged A. rotundatumnymphs in the same resting places of two toads and the absence of this species in the dragged areas suggest a nidicolous behavior at the studied site.

COMPARAÇÃO DAS PROPRIEDADES REOLÓGICAS DA MASSA DE CACAU TORRADA CONVENCIONALMENTE E POR MICROONDAS

Foram comparados, em termos de viscosidade, os efeitos de dois tipos de torração de cacau: convencional, em forno elétrico rotativo e por microondas, em protótipo de forno rotativo contínuo (2450MHz). O cacau foi torrado tanto em amêndoas inteiras quanto fragmentadas em "nibs" nos dois equipamentos. A variável do tratamento por microondas foi a densidade de potência aplicada às amêndoas inteiras (254,45 a 290,80 Wh/kg) e aos "nibs" (227,27 a 262,23 Wh/kg), com tempo de residência constante (10 min). A variável do tratamento convencional foi o tempo de torração das amêndoas (40 a 44 min) e dos "nibs" (34 a 38 min), com temperatura na camisa do forno constante (150°C). A viscosidade foi medida em reômetro Brookfield (mod. RV-DVIII) a 40°C. A viscosidade plástica das amostras torradas em microondas foi, em geral, menor que a daquelas torradas em forno elétrico rotativo. As amostras torradas em fragmentos ("nibs") também apresentaram menor viscosidade em relação àquelas torradas em amêndoas inteiras em forno elétrico. Quando o tratamento foi por microondas, a viscosidade das amostras obtidas de amêndoas torradas inteiras foi menor que a das amostras torradas em "nibs". A análise sensorial realizada com três especialistas mostrou que o sabor das amostras torradas em microondas foi similar ao do "líquor" obtido da torração convencional, levando em consideração a redução de tempo deste novo processo.

Extracción de naringina de Citrus paradisi L. estudio comparativo y optimización de técnicas extractivas

Se realizó el estudio comparativo de distintas técnicas extractivas de naringina utilizando cáscaras de pomelo (Citrus paradisi). Las mejores condiciones de preparación previa del material son el fragmentado de cáscara fresca y el secado en estufa con posterior fragmentado. Para cáscara fresca resulta más conveniente la extracción con etanol puro por Soxhlet (obteniéndose 26g/kg de peso fresco), mientras que para cáscara seca los mejores resultados se obtienen en la extracción con la mezcla etanol-agua en las proporciones 70:30 por maceración (20g/kg de peso fresco) y reflujo (22g/kg de peso fresco). Se observaron evidencias de la importancia del agua en el proceso de extracción. Se determinaron los valores de concentración de naringina en cáscaras de distintas variedades de Citrus paradisi de la región del Noroeste Argentino.

Effect of polyphenol oxidase (PPO) and air treatments on total phenol and tannin content of cocoa nibs

Cocoa flavour is greatly influenced by polyphenols. These compounds undergo a series of transformations during cocoa processing leading to the characteristic cocoa flavour. The use of exogenous polyphenol oxidase (PPO) proved to be useful to reduce polyphenol content in cocoa nibs. The effect of a PPO associated or not with air over total phenol and tannin content was evaluated. Cocoa nibs were autoclaved and treated with a PPO or water in the absence or presence of an air flow for 0.5, 1, 2 and 3 hours. Total phenol content was reduced in PPO or water treatments, but when associated with air there was an increase in phenol content. Tannin content was reduced only by the treatment with water and air.

Fragmentação mecânica de amêndoas de cupuaçu (Theobroma grandiflorum)

O cupuaçu (Theobroma grandiflorum) é uma fruta nativa da região amazônica brasileira cujas sementes convenientemente fermentadas, secas e torradas podem ser utilizadas para a obtenção de um produto similar ao chocolate. Este trabalho objetivou pesquisar uma forma alternativa de quebra da amêndoa seca sem torrar, através de um beneficiador de cilindros, seguida da utilização de um jogo de peneiras para a separação das frações fragmentadas. Os fatores estudados no rendimento da obtenção dos nibs (cotilédones fragmentados) e na verificação da pureza deste material (percentual de casca e gérmen) foram a umidade da amêndoa inteira e a velocidade diferencial dos cilindros de borracha do beneficiador. Pelos resultados obtidos, verificou-se que a umidade da amêndoa inteira foi a variável que apresentou maior influência na quebra. Os maiores percentuais de recuperação de nibs foram conseguidos na umidade de 5%. A variação dos níveis da velocidade diferencial não causou diferença significativa no rendimento de obtenção dos nibs. Em relação aos valores dos percentuais de casca e gérmen nos nibs, nenhuma variável estudada apresentou influência significativa nos valores desta resposta, mesmo assim todos os resultados foram bastante satisfatórios, apresentando valores abaixo de 1,75%. O rendimento deste processo alternativo está em torno de 90% de obtenção dos cotilédones encontrados em uma determinada massa de amêndoas. Como conclusão, o processo proposto constituiu-se em alternativa mecanizada tecnicamente válida, que apresentou bom rendimento de recuperação dos nibs, com percentuais de casca e gérmen abaixo do tolerado.

Qualidade nutricional das proteínas de cupuaçu e de cacau

O cupuaçu desponta como um importante produto agrícola de exportação com ampla perspectiva de mercado devido à aceitação que desfruta entre os consumidores regionais e de outros estados do país. O presente estudo teve como objetivo avaliar a qualidade protéica de produtos em pó formulados com amêndoas torradas de cupuaçu e cacau. De acordo com o ensaio biológico Net Protein Ratio, realizado a partir de dietas contendo 10% de proteína na proporção de cupuaçu ou cacau:caseína (50:50), verificou-se que as proteínas do cupuaçu apresentaram valor biológico significativamente superior (p < 0,05) ao das proteínas de cacau, promovendo aumento de peso dos animais 57,4% maior. No que se refere às necessidades diárias para crianças e adultos, o perfil aminoacídico das proteínas do cupuaçu teve desempenho superior ao das proteínas do cacau.