4 research outputs found
Crude oil burning mechanisms:A conceptual model review
No full textIn order to improve predictions for the burning efficiency and the residue composition of in-situ burning of crude oil, the burning mechanism of crude oil was studied in relation to the composition of its hydrocarbon mixture, before, during and after the burning. The surface temperature, flame height, mass loss rate and residues of three hydrocarbon liquids (n-octane, dodecane and hexadecane), two crude oils (DUC and REBCO) and one hydrocarbon liquid mixture of the aforementioned hydrocarbon liquids were studied using the Crude Oil Flammability Apparatus. The experimental results were compared to the predictions of four conceptual models that describe the burning mechanism of multicomponent fuels. Based on the comparisons, hydrocarbon liquids were found to be best described by the Equilibrium Flash Vaporization model, showing a constant gas composition and gasification rate. The multicomponent fuels followed the diffusion-limited gasification model, showing a change in the hydrocarbon composition of the fuel and its evaporating gases, as well as a decreasing gasification rate, as the burning progressed. This burning mechanism implies that the residue composition and burning efficiency mainly depend on the highest achievable oil slick temperature. Based on this mechanism, predictions can then be made depending on the hydrocarbon composition of the fuel and the measured surface temperature
Automated Signal Processing Applied to Volatile-Based Inspection of Greenhouse Crops
No full textGas chromatograph–mass spectrometers (GC-MS) have been used and shown utility for volatile-based inspection of greenhouse crops. However, a widely recognized difficulty associated with GC-MS application is the large and complex data generated by this instrument. As a consequence, experienced analysts are often required to process this data in order to determine the concentrations of the volatile organic compounds (VOCs) of interest. Manual processing is time-consuming, labour intensive and may be subject to errors due to fatigue. The objective of this study was to assess whether or not GC-MS data can also be automatically processed in order to determine the concentrations of crop health associated VOCs in a greenhouse. An experimental dataset that consisted of twelve data files was processed both manually and automatically to address this question. Manual processing was based on simple peak integration while the automatic processing relied on the algorithms implemented in the MetAlignTM software package. The results of automatic processing of the experimental dataset resulted in concentrations similar to that after manual processing. These results demonstrate that GC-MS data can be automatically processed in order to accurately determine the concentrations of crop health associated VOCs in a greenhouse. When processing GC-MS data automatically, noise reduction, alignment, baseline correction and normalisation are required
<i>In situ</i> biodegradation, photooxidation and dissolution of petroleum compounds in Arctic seawater and sea ice
No full textIn pristine sea ice-covered Arctic waters the potential of natural attenuation of oil spills has yet to be uncovered, but increasing shipping and oil exploitation may bring along unprecedented risks of oil spills.We deployed adsorbents coated with thin oil films for up to 2.5 month in ice-covered seawater and sea ice in Godthaab Fjord, SW Greenland, to simulate and investigate in situ biodegradation and photooxidation of dispersed oil.GC-MS-based chemometric methods for oil fingerprinting were used to identify characteristic signatures for dissolution, biodegradation and photooxidation. In sub-zero temperature seawater, fast degradation of n-alkanes was observed with estimated half-life times of ∼7 days. PCR amplicon sequencing and qPCR quantification of bacterial genes showed that a biofilm with a diverse microbial community colonised the oil films, yet a population related to the psychrophilic hydrocarbonoclastic gammaproteobacterium Oleispira antarctica seemed to play a key role in n-alkane degradation. Although Oleispira populations were also present in sea ice, we found that biofilms in sea ice had 25 to 100 times lower bacterial densities than in seawater, which explained the non-detectable n-alkane degradation in sea ice. Fingerprinting revealed that photooxidation, but not biodegradation, transformed polycyclic aromatic compounds through 50 cm-thick sea ice and in the upper water column with removal rates up to ∼1% per day.Overall, our results showed a fast biodegradation of n-alkanes in sea ice-covered seawater, but suggested that oils spills will expose the Arctic ecosystem to bio-recalcitrant PACs over prolonged periods of time
Rotulagem, qualidade e segurança biológica de alimentos para animais de companhia e seu impacto na saúde
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Ciência dos Alimentos, Florianópolis, 2013.Nas últimas décadas houve um aumento considerável na comercialização de alimentos para animais de companhia. Com foco na garantia desses alimentos, o presente trabalho obteve dados sobre o perfil qualitativo e de segurança de produtos comercializados em diferentes continentes, relacionando a influência de contaminantes biológicos presentes nos alimentos com possíveis danos a saúde animal. As etapas iniciais de desenvolvimento e obtenção de dados foram baseadas na certificação de concordância das informações descritas na rotulagem com a legislação vigente, além da verificação da veracidade das informações nutricionais do produto final embalado. Com relação à adequação de layouts de alimentos secos para cães comercializados no Brasil, 100% das amostras estavam em discordância com as exigências estabelecidas em lei. Já na verificação da veracidade dos níveis de garantia nutricional declarados na rotulagem de alimentos destinados a cães e gatos, 44% não correlacionaram os níveis nutricionais presente no alimento com os níveis de garantia estabelecidos e 36% das amostras estavam em desacordo com níveis nutricionais mínimos preconizados para a manutenção e desenvolvimento animal. Indicadores de qualidade e segurança alimentar também foram avaliados com o intuito de investigar a presença de contaminantes biológicos, incluindo seus metabólitos tóxicos até então não discutidos em alimentação destinada a animais de companhia (como sujidades leves e formação de aminas bioativas). No estudo de indicadores de condições higiênico-sanitárias de amostras de alimentos secos para cães e gatos, as contagens totais (cargas bacterianas e fúngicas) estavam dentro de valores considerados aceitáveis para consumo. No entanto, fungos micotoxigênicos foram isolados: gênero Aspergillus (A. parasiticus, A. niger e A. ochraceus) e Penicillium (P. expansum). A presença de agentes bacterianos em alimentos para cães e gatos (ricos em proteínas) pode favorecer a produção de aminas bioativas (biogênicas e poliaminas), importantes indicadores das condições higiênico-sanitárias aplicadas durante as etapas de produção do alimento final, assim como podem ser tóxicas à saúde animal. A principal amina biogênica detectada foi a histamina10(96%), seguida pelas putrescina e cadaverina (92%). À partir do conhecimento do perfil qualitativo biológico dos alimentos secos, esses dados foram correlacionados com diferentes formas de exposição do produto nos pontos de venda (embalagens abertas e/ou lacradas) e riscos associados a segurança alimentar. Em avaliação realizada para verificar as condições de comercialização em embalagens abertas (à granel) de alimentos completos para cães e pássaros, essa forma de exposição proporcionou aumento nos teores de umidade e atividade de água, favorecendo o crescimento de fungos toxigênicos e micotoxinas. A presença de insetos, ácaros e pêlos de roedores no produto final também devem ser considerados como importantes veiculadores desses agentes biológicos (bactérias, fungos e micotoxinas). Na avaliação de alimentos para cães comercializados em embalagens lacradas, 87% das amostras continham algum tipo de sujidade biológica leve (fragmentos de insetos e ácaros). Com relação aos ensaios micológicos, foi observado contaminação em todas as amostras, com presença dos gêneros Aspergillus (80,6%) e Penicillium (54,8%), e contaminação por fumonisinas em 32,2% das amostras. A partir dos diversos dados, foi possível obter subsídios para futuras discussões e revisões sobre os padrões legais vigentes e limites de tolerância estabelecidos, garantindo a saúde dos animais consumidores. Lembrando que a dieta de animais de companhia é baseada em somente um tipo de alimento, o qual consumido diariamente, amplifica a exposição a possíveis contaminantes biológicos presente na dieta.Abstract : A considerable increase in the marketing of pet foods has been observed in recent decades. With a focus on ensuring these foods, this study obtained data on the qualitative and safety of products marketed in different continents, relating the influence of biological contaminants in foods with possible damage to animal health. The initial stages of development and obtaining data were based on the labeling information and certification of regulation compliance, beyond to check the accuracy of the nutritional information of the final packaged product. Regarding the adequacy of layouts dry dog food sold in Brazil, 100 % of the samples were not in accordance with the requirements established by regulation. Respect the check the accuracy of the guarantee levels declared in nutrition labeling of dogs and cats foods, 44 % did not correlate the levels present in food with nutritional levels established warranty and 36 % of the samples were in disagreement with minimum nutritional levels recommended for the maintenance and animal development. The food quality and safety indicators were also evaluated in order to investigate the presence of biological contaminants, including toxic metabolites not previously discussed on pet food (such as light filth and bioactive amines formation). In the study of indicators of hygienic-sanitary conditions of dogs and cats dry food samples, the total counts (bacterial and fungal loads) values were considered acceptable for animal consumption. However, mycotoxigenic fungi were isolated: Aspergillus (A. parasiticus, A. niger and A. ochraceus) and Penicillium (P. expansum). The presence of bacterial agents in dogs and cats food (in which are rich in proteins) may favor the bioactive amines formation (biogenic and polyamines), important indicators of the sanitary conditions applied during the final food production, as can be toxic to animal health. The main biogenic amine detected was histamine (96 %), followed by putrescine and cadaverine (92 %). From the knowledge of biological qualitative profile of dry foods, these data were correlated with different forms of product presentation at point of sale (opened packages and/or sealed) and risks associated with food safety. In evaluation performed to check the marketing conditions in opened packages (open bulk bags) of dogs and birds food, this form of exposure12increased the moisture content and water activity, favoring the toxigenic fungi growth and mycotoxins production. The presence of insects, mites and rodents hair in the final product must also be considered important biological agents carrier (bacteria, fungi and mycotoxins). In the evaluation of dog food sold in sealed packages, 87 % of samples contained some sort of biological light filth (as fragments of insects and mites). Respect to the mycological tests, contamination was observed in all samples, with the presence of genera Aspergillus (80.6 %) and Penicillium (54.8 %), and fumonisin contamination in 32.2 % of samples. From the various data, it was possible to obtain a basis for future discussions and reviews on current standards regulation and tolerance limits established, ensuring animal health consumers. Important to mention that the pet animals diet is based on monotype food, which consumed daily, amplifies the potential exposure to biological contaminants present in the diet
