Avaliação de métodos rápidos para a quantificação de Staphylococcus aureus em alimentos.

O objetivo do trabalho foi avaliar métodos rápidos para a quantificação de S. aureus em alimentos

Опыт участия в международном летнем кампусе РАНХиГС 2017

Extraordinarily well-preserved chitinozoans from an Upper Silurian sedimentary sequence in south-east Turkey were recovered from different depth levels, hand-picked from the palynological residue, cleaned and analysed by micro-FTIR and Curie point pyrolysis-gas chromatography-mass spectrometry. Hand-picked chitinozoans were predominantly represented by the genera Bursachitina, Calpichitina, Cingulochitina, Ancyrochitina, Angochitina and Pterochitina. Both spectroscopic and pyrolytic investigations suggest that biogeomacromolecules of these Chitinozoa consist of both aliphatic and aromatic moieties. The micro-FTIR spectra of Chitinozoa are characterized by aliphatic CH, (3000-2800 and 1460-1450 cm(-1)) and CH3 (1375 cm(-1)) absorptions and aromatic C = C (1560-1610 cm(-1)) and CH (3050 cm(-1) and 700-900 cm(-1)) absorptions. Major pyrolysis products from the Chitinozoa include both aromatic compounds such as alkylbenzenes, alkylnaphthalenes, alkylphenols and alkylphenanthrenes and aliphatic hydrocarbons including a homologous series of n-alkene/n-alkane doublets. Aromatic compounds predominate over aliphatic compounds. 1,2,3,4-Tetramethylbenzene is the most abundant pyrolysis product of the studied Chitinozoa. No pyrolysis products diagnostic of chitin were detected in the present study and it is unlikely that the original biomacromolecules of Chitinozoa prior to fossilization were made of chitin. (c) 200

Comparison of quantification methods to measure fire-derived (black/elemental) carbon in soils and sediments using reference materials from soil, water, sediment and the atmosphere

Black carbon (BC), the product of incomplete combustion of fossil fuels and biomass (called elemental carbon (EC) in atmospheric sciences), was quantified in 12 different materials by 17 laboratories from different disciplines, using seven different methods. The materials were divided into three classes: (1) potentially interfering materials, (2) laboratory-produced BC-rich materials, and (3) BC-containing environmental matrices (from soil, water, sediment, and atmosphere). This is the first comprehensive intercomparison of this type (multimethod, multilab, and multisample), focusing mainly on methods used for soil and sediment BC studies. Results for the potentially interfering materials (which by definition contained no fire-derived organic carbon) highlighted situations where individual methods may overestimate BC concentrations. Results for the BC-rich materials (one soot and two chars) showed that some of the methods identified most of the carbon in all three materials as BC, whereas other methods identified only soot carbon as BC. The different methods also gave widely different BC contents for the environmental matrices. However, these variations could be understood in the light of the findings for the other two groups of materials, i.e., that some methods incorrectly identify non-BC carbon as BC, and that the detection efficiency of each technique varies across the BC continuum. We found that atmospheric BC quantification methods are not ideal for soil and sediment studies as in their methodology these incorporate the definition of BC as light-absorbing material irrespective of its origin, leading to biases when applied to terrestrial and sedimentary materials. This study shows that any attempt to merge data generated via different methods must consider the different, operationally defined analytical windows of the BC continuum detected by each technique, as well as the limitations and potential biases of each technique. A major goal of this ring trial was to provide a basis on which to choose between the different BC quantification methods in soil and sediment studies. In this paper we summarize the advantages and disadvantages of each method. In future studies, we strongly recommend the evaluation of all methods analyzing for BC in soils and sediments against the set of BC reference materials analyzed here