Fluorescence Spectroscopy Applied in the Identification of Lubricant Oils

In this work, we report the use of fluorescence spectroscopy to identify lubricant oils. Optical characterization was performed in four commercial lubricant oils that are used in reciprocating compressors. Mid-infrared absorption of samples indicates the presence of aromatic rings showing bands at 1605 cm-1 (C=C stretching) and 815 cm-1 (C–H stretch out of plane). UV-VIS absorption spectra show bands of di- and polyaromatic rings (around 230 nm and 260 nm, respectively). By exciting the samples at 360 nm, a broad emission band centered at 440 nm is observed, indicating that this excitation is appropriate to be used for the diagnosis of oil presence in the environment. DOI: http://dx.doi.org/10.17807/orbital.v10i1.103

Fluorescence Spectroscopy and Silica Gel Applied as a Tool for Capture and Detection of Compressor Lubricant Oils

Here, we report the use of fluorescence spectroscopy for the identification of lubricant oils used in reciprocating compressors, and the use of silica gel as an adsorbent to capture lubricant oil vapors. The silica gel was tested for adsorption of lubricant oil vapors, by heating the samples at 200°C, the emission spectrum of the lubricant oils is observed on the silica gel layer, over 20 min of heating. The spectrum of the lubricant oils over the silica gel layer presents a redshift, an indication of the degradation effect. In order to investigate this effect on the optical properties, we conducted an experiment by heating the samples at (130 ± 4) °C, and collected at different times. The MID-infrared absorption of the samples presents bands of oxygen-containing groups at 1010 and 1050 cm-1, and NIR infrared absorption measurements at 3444 cm-1 show an increase in the hydroperoxide band during the degradation time. These two results indicate that the oxidation process is associated with the observed redshift of the absorption and emission bands in lubricant oils and over the adsorbent layer

Reproductive Status of the social wasp Polistes versicolor (Hymenoptera, Vespidae)

A fundamental feature in the evolution of social insects is the separation of castes, and the presence of wide differentiation between castes indicates a more advanced degree of sociability. In this study, we evaluated factors that indicate the reproductive status of females in colonies of the social wasp Polistes versicolor. The reproductive status of each female was examined by measuring nine morphometric characters, by the cuticular chemical profile, insemination and by her relative age. We conclude that in P. versicolor colonies there are 3 female groups that show cuticular chemical profile difference. The first group belong to females with ovarioles filamentous, typical of workers; the second is females with ovarioles intermediates; and the third is a group of queens, which are older females, inseminated and with greater degree of ovarian development found among all females. On the other hand, there was no significant morphological differences between these female groups. Therefore, although no significant morphological differences among females there are other factors such as the cuticular chemical composition that is an indicative of reproductive physiological condition of female in the colony

Nanocompósitos de sílica e nanotubos de carbono obtidos pelo método sol-gel e a técnica de alta pressão

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Fluorescence Spectroscopy Applied in the Identification of Lubricant Oils

In this work, we report the use of fluorescence spectroscopy to identify lubricant oils. Optical characterization was performed in four commercial lubricant oils that are used in reciprocating compressors. Mid-infrared absorption of samples indicates the presence of aromatic rings showing bands at 1605 cm-1 (C=C stretching) and 815 cm-1 (C–H stretch out of plane). UV-VIS absorption spectra show bands of di- and polyaromatic rings (around 230 nm and 260 nm, respectively). By exciting the samples at 360 nm, a broad emission band centered at 440 nm is observed, indicating that this excitation is appropriate to be used for the diagnosis of oil presence in the environment. DOI: http://dx.doi.org/10.17807/orbital.v10i1.103

Evaluation of Inter and Intraspecific Differences in the Venom Chemical Compositions of Polybia paulista Wasps and Ectatomma brunneum Ants Using FTIR-PAS

Wasps can synthesize chemical compounds called venom whose function is to overcome prey and assist in defense of the colonies. Geographic Parameters such as sex, age, the season of the year, and diet determined the composition of the venom location, genetics, environment. However, studies on the compositional variability of venom are still limited due to the difficulty in obtaining samples and the complexity of these substances. This work describes the use of the Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) to investigate inter- and intraspecific variability in the venom chemical composition (VCC) of the social wasp Polybia paulista (Von Ihering 1896) and the ant Ectatomma brunneum (Smith 1858). The results reveal significant differences in VCC among the ant and wasp, even for samples obtained from the same environment. The genetic component, therefore, seemed to be the predominant factor determining the compounds present. The findings also showed that exogenous factors, such as diet, could also be responsible for intraspecific differences, especially in wasps. The FTIR-PAS technique proved to be a reliable way of assessing intra- and interspecific differences in social Hymenoptera VCC

Linear Alkanes and Reproductive Status of Polistes versicolor (Hymenoptera: Vespidae) Females in Winter Aggregates

Female wasps such as Polistes versicolor can form aggregates to face weather conditions that are not suitable to sustain their colonies. The interactions between individuals in these aggregates, just as in other associations, are probably facilitated by chemical signals. Of these compounds some of the most efficient during social interactions of insects are those called contact pheromones or superficial pheromones. This special type of pheromones, known as cuticular hydrocarbons, can be found in insects cuticle. They facilitate the differentiation of caste, species and nestmates, and may be important indicators of dominance as well as fertility. Some studies indicate that linear alkanes are important cuticular compounds for intraspecific recognition and discrimination. The aim of this study was to evaluate the relationship between reproductive physiologic condition and the linear alkanes present in the cuticle of females of P. versicolor in aggregates employing Gas Chromatography with Flame Ionization Detector (GC-FID). Females from distinct aggregates were differentiated by the chemical composition of their cuticle. In each aggregate, there was difference in cuticular chemical composition between females with different ovarian development degrees, allowing the distinction between inseminated and non-inseminated females

Animal production in tropical pastures of Latin America

Animal production in Latin America based on tropical pastures contributes significantly to the Agricultural Gross Domestic Product (GDP). Edapho-climatic conditions and the land tenure system are among the determining factors of different types of animal production in various countries. Based on climatic characteristics, it is possible to divide Latin American tropical livestock production systems into those of dry areas, savannahs and humid areas. Dual-purpose animals account for the bulk of total livestock in tropical Latin America, with management in native pastures predominating. Measures to increase animal production in the region should include the use of more productive forage varieties adapted to different areas, appropriate pasture and herd management procedures and animal and plant genetic improvement, among others. Two of the main obstacles to greater livestock production are the degraded state of many pastures and the need to control the emission of greenhouse gases. In order to meet the increased demand for food, especially those of animal origin, efforts to increase production should prioritize the recovery of degraded pastures, greater use of integrated systems incorporating legumes and proper management practices, aimed at reducing the emission of greenhouse gase

In Vitro Schistosomicidal Activity of Some Brazilian Cerrado Species and Their Isolated Compounds

Miconia langsdorffii Cogn. (Melastomataceae), Roupala montana Aubl. (Proteaceae), Struthanthus syringifolius (Mart.) (Loranthaceae), and Schefflera vinosa (Cham. & Schltdl.) Frodin (Araliaceae) are plant species from the Brazilian Cerrado whose schistosomicidal potential has not yet been described. The crude extracts, fractions, the triterpenes betulin, oleanolic acid, ursolic acid and the flavonoids quercetin 3-O-beta-D-rhamnoside, quercetin 3-O-beta-D-glucoside, quercetin 3-O-beta-D-glucopyranosyl-(1-2)-alpha-L-rhamnopyranoside and isorhamnetin 3-O-beta-D-glucopyranosyl-(1-2)-alpha-L-rhamnopyranoside were evaluated in vitro against Schistosoma mansoni adult worms and the bioactive n-hexane fractions of the mentioned species were also analyzed by GC-MS. Betulin was able to cause worm death percentage values of 25% after 120 h (at 100 mu M), and 25% and 50% after 24 and 120 h (at 200 mu M), respectively; besides the flavonoid quercetin 3-O-beta-D-rhamnoside promoted 25% of death of the parasites at 100 mu M. Farther the flavonoids quercetin 3-O-beta-D-glucoside and quercetin 3-O-beta-D-rhamnoside at 100 mu M exhibited significantly reduction in motor activity, 75% and 87.5%, respectively. Biological results indicated that crude extracts of R. montana, S. vinosa, and M. langsdorffii and some n-hexane and EtOAc fractions of this species were able to induce worm death to some extent. The results suggest that lupane-type triterpenes and flavonoid monoglycosides should be considered for further antiparasites studies.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2006/60132-4, 2008/01268-9, 2009/00604-8]Coordenadoria de Aperfeicoamento de Pessoal do Ensino Superior (CAPES)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq