Spelling suggestions: "subject:"gcms"" "subject:"gcims""
601 |
Podzols of Ilha Comprida (SE, Brazil): organic matter chemistry and decay features / Espodossolos da Ilha Comprida (SP): química da matéria orgânica e feições de degradaçãoJosiane Millani Lopes 28 January 2016 (has links)
The most frequent soils in the São Paulo State Coastal Plain are Podzols, characterized by strong to moderate hydromorphic to well-drained podzolization with very well developed podzol-B horizons (Bh or Bhm). Podzolization processes include the effects of hydrology and rooting on profile morphology and the subsequent effects of improved drainage. A Podzol chrono-hydrosequence was described in detail on a cliff at the south coast of Ilha Comprida, a Holocene barrier island, and allowed a subdivision into four distinct groups: poorly-drained profiles, profiles with well-drained B horizons, strongly rooted profiles and superposed profiles. The morphological description and some observations about the exposure cliff were essential for grouping and differentiating the podzol profiles. Some well-drained podzols have OM-depleted mottles that are related to selective decomposition of organic matter (OM) by microorganisms. Such mottles are frequently associated to root channels. Seventeen profiles were studied, thirteen had depletion mottles scattered along the profile. Most of these mottles are whitish and are located preferentially in the horizons of transition between the E and B horizons, particularly in conditions of good drainage. Such mottles have certain morphological differences and may be grouped according to similarities in their morphology and their position in the profile. Distinct groups are: (a) concentric OM-depleted mottles; (b) circular/tubular OM-depleted mottles (burrows); (c) dotted OM-depleted mottles; (d) ghost OM-depleted mottles; (e) irregular OM-depleted mottles and (f) Fe-depleted mottles. The chemical composition of soil organic matter was studied in detail using pyrolysis in combination with gas chromatography/mass spectrometry (Py-GC/MS). Samples of all horizons of the distinct profiles studied were taken, as well as from the center of the mottle (M) and from the direct surroundings (S). The processes involved in the genesis of Podzols in the sandy coastal plain are directly related to drainage, the contribution of dissolved organic matter (DOM), the contribution of organic matter derived from roots, the chemical composition of organic matter and its decomposition by microorganisms, causing a large variation in adjacent Podzols. The well-drained Podzols differ in characteristics from the poorly drained ones in composition and deposition of OM, as well as its decomposition, which is directly related to the activity of groups of microorganisms. They also differ in the relative contribution of OM-derived from roots and DOM. There is a wide variation in the characteristics of decomposition by microorganisms between the profiles of Podzols permanently exposed to air and marine spray (the cliffs) on Ilha Comprida and those inland (pits). There are therefore two main processes that change the morphology of Podzols (OM and composition): (a) change in drainage and rooting, and (b) exposure to air. / Os solos mais frequentes na Planície Costeira do Estado de São Paulo são os podzóis, caracterizados por podzolização com hidromorfismo forte a moderado a bem drenado com horizontes B-podzol muito bem desenvolvidos (Bh ou Bhm). O processo de podzolização inclui os efeitos da hidrologia e do enraizamento no perfil e os efeitos subsequentes da drenagem melhorada. Uma crono-hidrosequencia de podzóis foi descrita em detalhes em um barranco na costa sul da Ilha Comprida, uma ilha barreira do Holoceno, e permitiu uma subdivisão em quatro grupos distintos: perfis mal drenados, perfis com horizonte B bem drenados, perfis fortemente enraizados e perfis superpostos. A descrição morfológica e algumas observações sobre o barranco exposto foram essenciais para o agrupamento e diferenciar os perfis de podzóis. Alguns desses podzóis bem drenados possuem manchas esbranquiçadas que estão relacionadas com a seletiva decomposição da matéria orgânica (MO) por microorganismos. Tais manchas são freqüentemente associadas aos canais radiculares. Foram estudados dezessete perfis, dos quais treze apresentaram manchas de esgotamento espalhadas ao longo do perfil. A maioria destas manchas são esbranquiçadas e estão localizadas preferencialmente nos horizontes de transição entre os horizontes E e B, particularmente em condições de boa drenagem. Tais manchas possuem algumas diferenças morfológicas e puderam ser agrupadas de acordo com semelhanças na sua morfologia e da sua posição no perfil. Os grupos são: (a) manchas concêntricas de depleção da MO; (b) manchas circulares/tubularess de depleção da MO (tocas); (c) manchas pontilhadas de depleção da MO; (d) manchas fantasmas de depleção da MO; (e) manchas irregulares de depleção da MO; e (f) manchas de depleção de Fe. A composição química da matéria orgânica do solo foi estudada em detalhe por pirólise em combinação com cromatografia em fase gasosa/espectrometria de massa (Py-CG/EM). Amostras de todos os horizontes dos perfis estudados foram coletadas, bem como amostras do centro das manchas (M) e do solo adjacente (S). Os processos envolvidos na gênese de podzóis da planície costeira arenosa estão diretamente relacionados com a drenagem, a contribuição de matéria orgânica dissolvida (MOD), a contribuição de matéria orgânica derivada de raízes, a composição química da matéria orgânica e sua decomposição por microorganismos, causando uma grande variação no podzóis. Os podzóis bem drenados diferem em características dos mal drenados em composição e deposição de MO, bem como a sua decomposição, que está directamente relacionada com a actividade dos grupos de microrganismos. Eles também diferem na contribuição relativa da MO derivada de raízes e MOD. Existe uma grande variação nas características da decomposição por microorganismos entre os perfis de podzóis permanentemente expostas ao ar e spray marinho (falésias) na Ilha Comprida e os do interior (trincheiras). Há, portanto, dois processos principais que alteram a morfologia de podzóis (composição da MO): (a) mudança na drenagem e enraizamento, e (b) a exposição ao ar.
|
602 |
An investigation into changes to trace metals and metabolic profiling in the diabetic retinaCallagy, Sandra January 2018 (has links)
Diabetes mellitus currently affects over 422 million people globally and over 80% of patients with diabetes will develop diabetic retinopathy. Patients with diabetic retinopathy initially develop background retinopathy, which does not cause significant deterioration of visual function; however, background retinopathy may progress and lead to proliferative diabetic retinopathy and diabetic macular oedema, both of which cause severe visual dysfunction if left untreated. Current therapies for diabetic retinopathy include invasive intravitreal injections and laser photocoagulation; however these treatments only attenuate the progression of proliferative diabetic retinopathy and diabetic macular oedema. Aside from prevention by maintaining good blood glucose and blood pressure control, there are currently no treatments to prevent progression to late-stage diabetic retinopathy and new innovations in the field have not significantly progressed. For this reason, we have used untargeted âomics approaches to identify previously unknown pathological pathways in diabetes. In this thesis, I have analysed a range of trace metals in donor retinas and found that total copper was increased in diabetic retinas compared with non-diabetic. This result was replicated in streptozotocin-induced diabetic rat retinas and further evidenced by upregulation of metallothioneins and caeruloplasmin in diabetic rat retinas compared with non-diabetic. Treatment with the copper chelator triethylenetetramine modulated these changes, the downstream effects of which require further study. This is the first description, to our knowledge, of dysregulated copper homeostasis in the diabetic retina. I have also mapped metabolic changes in streptozotocin-induced diabetic rat retinas and found previously undescribed metabolite changes such as diabetes-induced downregulation of scyllo inositol. This coincided with substantial changes to retinal lipids during diabetes and changes to individual lipids were consistent within their respective class. I have also found a pattern whereby regardless of the extent of change to a lipid class in diabetes, lipids containing docosahexaenoic acid (22:6 carbon chain) were consistently downregulated. This is thought to be the first study to describe this range of metabolite changes in the diabetic retina but also the first study to describe this range of metabolite analysis concomitantly within the same tissue sample. The data from this study provides new insights into metallomic and metabolic dysfunction in diabetic retinopathy and shown that these data are reproducible. We suggest that there is plenty of scope for further research to investigate mechanisms behind copper dysregulation, how this affects pathogenesis of diabetic retinopathy along with new insights into dysregulated metabolic pathways.
|
603 |
Investigation of selected organic compounds on water quality along the Olifants river catchmentMulanga, Tshimanga Christelle 06 1900 (has links)
Water is a crucial natural resource, indispensable to food production, life, the environment, power generation, industry, sanitation and hygiene. The presence of Organochlorine Pesticides (OCPs) in the environment is not wanted due to their negative effects on human beings and animals. As a result, there is a need to continuously monitor their presence in the environment. In this study, surface water samples were collected once a month during the dry season and during wet season from the selected five points along the Olifants River and stored at a temperature of < 50C before analysis. The OCPs were extracted with dichloromethane (DCM) using the Liquid-Liquid Extraction (LLE) method. After undertaking the sample through the clean- up process, the crude extracts obtained were put into the column chromatography and eluted with hexane, about 1.5 μL of the purified extracts were analysed by the Gas Chromatographic- Mass Spectrophotometer (GC/MS). The percentage recoveries, varied from 32- 116 % for p, p’-DDT and 4,4'-DDD respectively in triply spiked water samples. The standard deviation for most of the compounds is less than±0.04, with the exclusion of Heptachlor (±0.14). The seasonal variability of OCPs in water samples along Olifants River results show that in dry season, the Olifants River is mostly polluted at the Oxford site with (BHC-beta, Aldrin, Heptachlor-epoxide, Endosulfan-alpha and Endrin), at the Ga- Selati site with (Heptachlor-epoxide and Endrin) and at the Wolvekrans site with (Endosulfan-alpha), with Aldrin up to 834.20 ng/ L indicating the highest hazard toward the aquatic environment while in summer the Olifants River is mostly polluted at the Ga- selati site with BHC-beta and at the Waterval site with (Heptachlor and BHC-gamma) with BHC- gamma up to 560 ng/ L indicating the highest hazard toward the aquatic environment. The levels reached from the Olifants River catchment were meaningfully above the drinking water quality guidelines for organic chemical recommended by WHO, 2006 i.e. (BHC-gamma,DDT-44, Aldrin, dieldrin and Endrin are (2.0,1.0,0.03,0.03 and 0.6) respectively for the protection of the domestic use, aquatic ecology and agricultural use (irrigation and livestock watering) for compounds with local guideline values; while, the international water quality guidelines to protect the aquatic ecosystems are 0.00083 ng/mℓ (4,4’DDD), 0.00059 ng/mL (4,4’DDE), (4,4’DDT), 0.00021 ng/mL (heptachlor), 0.0092 ng/mℓ (α-HCH), 0.0186 ng/mL (γ- HCH), and chronic values are 0.056 ng/mL (ENDO I and II) and 0.0023 ng/mL endrin) (USEPA, 2002). Levels detected were significantly higher than some research studies conducted up to now in South African aquatic environments. These results confirm the contamination of the Olifants River catchment by the OCPs. / Water and Sanitation / M. Sc. (Environmental Science)
|
604 |
Improving the performances of the combustion engines by improving the ignition system / Amélioration des performances des moteurs à combustion par amélioration du système d'allumageAstanei, Dragoş-George 05 November 2014 (has links)
Face aux normes actuelles et futures, de plus en plus drastiques, concernant les émissions de polluants, les constructeurs automobiles cherchent en permanence à améliorer l'efficacité des moteurs à allumage commandé. Une des solutions les plus efficaces et applicables pour diminuer la quantité de polluants émis dans les gaz d’échappement (HC, CO, NOx) et réduire la consommation de carburant, est d’utiliser un mélange très pauvre (richesse du mélange inférieure à 0,6). Toutefois, ce concept de fonctionnement est limité par les systèmes d'allumage classiques qui ne peuvent pas garantir un allumage du mélange air / combustible dans de bonnes conditions, de manière à assurer une combustion complète, rapide et reproductible.Le sujet de cette thèse consiste en l'élaboration d'un nouveau système d'allumage basé sur une bougie d’allumage double, qui peut produire deux d'étincelles quasi-simultanées, dont la longueur cumulée est plusieurs fois plus élevée que celle d’étincelles produites par une bougie d'allumage classique. Pour valider ce système d'allumage, trois différents types d'analyses ont été réalisés: une analyse des paramètres électriques des décharges, un diagnostic du plasma par spectroscopie optique d'émission, et des essais in situ du système d'allumage sur deux moteurs à combustion interne avec analyse des gaz d'échappement et détermination des performances des moteurs.Ces tests ont révélé que l'utilisation du système d’allumage à double étincelle peut assurer une meilleure stabilité dans le fonctionnement du moteur (en particulier dans les conditions d'allumage difficiles, en utilisant des mélanges très pauvres) ; des performances accrues du moteur pour une même quantité de carburant consommé ; et une diminution de la quantité d’hydrocarbures imbrûlés et de monoxyde de carbone dans les gaz d'échappement, mais avec une plus grande émission d'oxydes d'azote par rapport à un système d'allumage classique. / Faced with the current and future more and more drastic standards for pollutant emissions, the car manufacturers are permanently trying to improve the efficiency of spark ignition engines. One of the most effective applicable solutions for reducing the quantity of pollutant emissions (HC, CO, NOx) from the exhaust gases and also to reduce the fuel consumption is to operate with very lean mixture (equivalent ratio lower than 0.6). However, this operation concept is limited by the actual ignition systems that cannot assure an air/fuel mixture ignition in good conditions, in order to assure a complete, fast and repeatable combustion. The subject of this thesis consists into developing of a new ignition system based on a double spark plug, which can produce two quasi-simultaneous spark discharges with cumulated length few times higher than the sparks produced by a conventional spark plug. For ignition system validation, three different types of analysis have been considered: the analysis of the discharges electrical parameters, the plasma diagnosis using optical emission spectroscopy methods and the tests of the ignition system on two internal combustion engines with the exhaust gases analysis and engine performances determination. The tests revealed that the utilization of the double spark ignition system can assure a better stability in engine operation (especially in difficult ignition conditions such using very lean mixtures), increased engine performances for the same amount of consumed fuel and it can provide a diminution of the unburned hydrocarbons and carbon monoxide quantities from the exhaust gases, but with an increased quantity of nitrogen oxides, compared with a conventional ignition system.
|
605 |
Desenvolvimento e aplicação de uma nova fase para extração por sorção em barra de agitação (SBSE) / Development and application of a new phase for stir bar sorptive extraction (SBSE)Juliana Yamashita Barletta 17 December 2010 (has links)
Uma fase polimérica inédita de polidimetilsiloxano/carvão ativado (PDMS-ACB) é proposta como fase extratora para extração por sorção em barras de agitação (SBSE). A barra de PDMS-ACB foi desenvolvida no laboratório usando um molde de teflon simples, demonstrando estabilidade e resistência aos solventes orgânicos. Utilizando uma única barra de PDMS-ACB mais de 150 extrações foram realizadas sem qualquer dano. A barra de SBSE contém aproximadamente 100 µL de revestimento polimérico, 2,36 mm de diâmetro e 2,2 cm de comprimento. A barra PDMS-ACB foi aplicada na extração de seis pesticidas (ametrina, atrazina, bifentrina, carbofurano, metribuzim e tebutiurom), com propriedades predominantemente polares, comumente aplicados em plantações de cana-de-açúcar. A barra PDMS-ACB foi utilizada na determinação de pesticidas em garapa através de cromatografia gasosa hifenada à espectrometria de massa (GC-MS). O planejamento experimental foi empregado na etapa de otimização da extração SBSE, um planejamento fatorial fracionado avaliou a influência dos principais parâmetros envolvidos. Posteriormente, o planejamento composto central (CCD) com conformação estrela foi explorado para otimizar os fatores significativos na extração. Apenas 200 µL de acetato de etila foram utilizados como solvente na dessorção líquida (LD). Para os compostos avaliados, o método apresentou limite de quantificação (LOQ) no intervalo de 0,5 - 40 µg L-1, as recuperações variaram entre 0,18 - 49,50 % e a precisão intra-dia variou de 0,072 - 8,40 %. Concluída a etapa de validação, o método foi aplicado em amostras reais de garapa disponíveis comercialmente em São Carlos-SP. / A novel polydimethylsiloxane/activated carbon (PDMS-ACB) is proposed as new polymeric phases for stir bar sorptive extraction (SBSE). The PDMS-ACB was developed in lab using simple teflon\'s mold, demonstrating remarkable stability and resistance to organic solvents, over 150 extractions without any damage. SBSE bar contained 100 µL of polymeric coating, a diameter of 2.36 mm and a length of 2.2 cm. It was applied to the determination of pesticides (ametryn, atrazine, bifenthrin, carbofuran, metribuzine and tebuthiuron) having predominantly polar properties, applied in sugarcane crops. PDMS-ACB was employed in the determination of pesticides in sugarcane juice using gas chromatography coupled to mass spectrometry (GC-MS). Experimental design was employed in the optimization step, a fractional factorial evaluated the main parameters involved in the extraction procedure. Afterwards, central composite design (CCD) was exploited to optimize the significant factors on the extraction. About 200 µL of ethyl acetate were employed as solvent in the liquid desorption (LD). The method presented limit of quantification (LOQ) from 0.5 to 40 µg L-1, recoveries varied 0.18 - 49.50% and precision intra-day 0.072 - 8.40%. Hence, the method was applied to the analysis of real sugarcane juice samples commercially available in São Carlos-SP.
|
606 |
Desenvolvimento e validação de método para determinação de hidrocarbonetos policíclicos aromáticos em camarão (Litopenaeus vannamei) / Method development and validation for polycyclic aromatic hydrocarbons determination in shrimp (Litopenaeus vannamei)Vilela Júnior, Antônio Rodrigues 24 February 2017 (has links)
Brazil is among the ten largest cultivated shrimp producers in the world, with the northeast being the largest producer of shrimp cultivated in the country. These regions of cultivation may undergo strong anthropic stress due contamination by all sort of compounds, including the polycyclic aromatic hydrocarbons (PAH). These compounds have been the source of several studies because they are considered mutagenic and carcinogenic. The objective of this work is to develop an analytical method based on the matrix solid phase dispersion (MSPD) and gas chromatography coupled to mass spectrometry for determination of 16 PAH in shrimp. The optimal working conditions were 0.5 g of the sample; 0.5 g of C18; 1.5 g of alumina; 150 seconds of homogenization and 8 mL of acetonitrile as the elution solvent. These last three variables were established through a factorial design of 23 with triplicate at the central point plus six axial points, evaluating them by the methodology of response surface analysis. The validation of the analytical method presented linearity in the range of 0.9915 to 0.999 and sensitivity in the concentration range of 5 to 100 ng g -1; selectivity based on matrix effect, accuracy and precision, with recovery values between 70 - 104% coefficients of variation lower than 13%, in the three levels of fortification (10, 25 and 50 ng g -1); (dry weight) limits of 0.7 to 5.0 ng g -1 and 1 to 5 ng g -1 respectively, the robustness was evaluated through the contour charts, which indicated that the method can be considered robust. This method was applied in four samples (A, B, C and D), with HPA predominating from 2 to 4 rings, sample A being the one with the highest concentration (280 ng g-1 for total PAH). In the three samples (A, B and C) benzo [a] anthracene have reached concentrations of 21, 18 and 14 ng g-1 respectively, which is considered probable carcinogenic to humans. The method was considered efficient in the extraction of PAH, when compared to the methods reported in the literature. It integrates the process of extraction and cleaning in a single and economical method and the consumption of materials used during the process is minimized. / O Brasil está entre os dez maiores produtores de camarão do mundo, sendo a região nordeste a maior produtora de camarão cultivado no país. As regiões de cultivo estão sob forte estresse ambiental, acarretando contaminação por vários compostos, incluindo os hidrocarbonetos policíclicos aromáticos (HPA). Estes compostos têm sido fonte de diversos estudos, por apresentarem propriedades mutagênicas e carcinogênicas. Diante do exposto, este trabalho objetiva desenvolver um método analítico baseado na técnica de dispersão da matriz em fase sólida (MSPD) e cromatografia gasosa acoplada à espectrometria de massas, para determinação de 16 hidrocarbonetos policíclicos aromáticos (HPA) em camarão. As condições ótimas de trabalho foram 0,5 g da amostra; 0,5 g de C18; 1,5 g de alumina; 150 segundos de homogeneização e 8 mL de acetonitrila como solvente de eluição. Estas três últimas variáveis estabelecidas através de um planejamento fatorial 23 com triplicata no ponto central mais seis pontos axiais, avaliando-as pela metodologia de análise de superfície de resposta. A validação do método analítico apresentou linearidade na faixa de 0,9915 a 0,999 e sensibilidade no intervalo de concentração de 5 a 100 ng g-1; seletividade com base no efeito de matriz, exatidão e precisão, com valores de recuperação entre 70 - 104% coeficientes de variação inferiores a 13%, nos três níveis de fortificação (10, 25 e 50 ng g-1); limites de detecção e quantificação (peso seco) de 0,7 a 5,0 ng g-1 e 1 a 5 ng g-1 respectivamente; robustez foi avaliada através dos gráficos de contorno, o qual indicou que o método pode ser considerado robusto. Este método foi aplicado em quatro amostras (A, B, C e D), com predominância dos HPA de 2 a 4 anéis, sendo a amostra A com a maior concentração total de HPA, 280 ng g-1. Nas amostras A, B, C foram encontrados benzo[a]antraceno 21; 18 e 14 ng g-1, respectivamente, este que é considerado provável cancerígeno ao homem. O método pode ser considerado eficiente na extração de HAP, quando comparado aos métodos relatados na literatura. Integra o processo de extração e limpeza em uma única etapa e econômico, pois o consumo de materiais e minimizado. / São Cristóvão, SE
|
607 |
Composição química e capacidade sequestrante de espécies reativas de oxigênio e nitrogênio de mel orgânico brasileiro / Chemical composition and Nitrogen and Oxygen Reactive Species scavenging activity of Brazilian organic honeyCamila Furtunato da Silva 21 July 2017 (has links)
O Brasil apresenta grande potencial para a exploração da apicultura, dado ao seu vasto território e flora diversificada, o que permite diferentes variedades de méis com propriedades únicas. O estado do Paraná é um dos maiores produtores de méis do país e o investimento em produção que atenda aos mercados mais exigentes estimulou a produção do mel orgânico. O conhecimento desde a antiguidade sobre os efeitos benéficos à saúde pelo mel vem estimulando a pesquisa deste alimento nobre. Assim, este trabalho teve por objetivo estudar méis orgânicos brasileiros certificados (MO) para a caracterização do perfil fenólico, volátil, além da avaliação da capacidade de sequestro das espécies reativas de oxigênio e nitrogênio. Os méis foram coletados nos apiários de apicultores com certificação orgânica de dois municípios do sul do Paraná, General Carneiro e Turvo-PR. Nos ensaios foram utilizados extratos fenólicos dos méis, obtidos por meio da utilização da resina Amberlite® XAD®2, bem como méis brutos in natura. Os extratos apresentaram conteúdo de compostos fenólicos significativo, sendo o melato (MO5), de General Carneiro, o de maior teor (117,68± 4,40 mg EAG/g). Para as análises de sequestro das espécies reativas de oxigênio e nitrogênio, os extratos fenólicos foram sempre superiores aos méis brutos in natura. Os extratos fenólicos, de maneira geral, apresentaram alta capacidade de sequestro para o radical peroxila (ROOo), ácido hipocloroso (HOCl) e óxido nítrico (NOo). Em relação aos melatos, o extrato MO7 apresentou alta capacidade para o sequestro do HOCl (EC50= 4,83 ± 0,13 ?g/mL), enquanto que o MO5 foi melhor para o sequestro do NOo (EC50=2,16 ± 0,18 ?g/mL). Pelo método HPLC-ABTS on-line foi possível identificar e quantificar a contribuição para a atividade antioxidante do ácido ferúlico no extrato (MO1) e do flavonoide kanferol na amostra (MO4). O ácido ascórbico foi identificado e quantificado por HPLC somente nos melatos (MO3, MO5 e MO7). Pela técnica de LC-MS/MS foram identificados a presença dos seguintes compostos fenólicos: ácido caféico, rutina e hesperidina em todos os extratos. A análise de compostos voláteis por SPME-CG/EM mostrou a presença de dois compostos, encontrados apenas nos melatos, que foram o terpineno-4-ol, que possui ação antifúngica, antiparasitológica e anti-inflamatória; e o 3,4-dimetil-1-deceno, podendo assim serem utilizados como marcadores químicos destes méis. O conhecimento da composição química destes méis, bem como a composição fenólica bioativa, contribui para o fornecimento de antioxidantes naturais para a dieta, atenuando assim os efeitos negativos dos radicais livres / Brazil has a great potential to explore beekeeping due to its vast territory and diversified flora, what allows different varieties of honeys with unique characteristics. Parana state is one of the largest honey producers and the investment in production that meets the most demanding markets stimulated the organic honey production. The knowledge since early in history regarding the beneficial health effects promoted by honey is stimulating the scientific research of this noble food. Thus, this paper aimed to study certified Brazilian organic honeys (MO) in order to determine the phenolic and volatile profiles, and also the evaluation of radical scavenging capacity against Nitrogen and Oxygen Reactive Species (RNS and ROS, respectively). The honeys were collected from apiaries from beekeepers with the organic certification from two municipalities of southern Parana, General Carneiro and Turvo, PR. In the essays, phenolic extracts were obtained from honeys by using Amberlite® XAD®2 resin, as well as crude in natura honeys. The extracts showed a significant content in phenolic compounds, with honeydew (MO5), from General Carneiro, showing the highest content (117,68 ± 4,40 mg AGE/g). For the analyzes to determine the radical scavenging capacity against RNS and ROS, the phenolic extracts always showed up superior results in comparison to crude in natura honeys. Phenolic extracts showed, in general, great capacity to scavenge peroxyl radical (ROOo), hypochlorous acid (HOCl) and nitric oxide (NOo). In relation to honeydews MO7 extract showed the highest capacity to scavenge HOCl (IC50= 4,83 ± 0,13 ?g/mL) while MO5 was the sample with better capacity to scavenge NOo (IC50=2,16 ± 0,18 ?g/mL). By using HPLC-ABTS on-line method it was possible to identify and to quantify the ferulic acid in MO1 extract, a compound with an important contribution to the antioxidant activity of this sample, as well as the flavonoid kaempferol in MO4 sample. Ascorbic acid was identified and quantified by HPLC only in the honeydew samples (MO3, MO5 and MO7). The analyzes developed by LC-MS/MS techniques indicated the presence of the phenolic compounds caffeic acid, rutin and hesperidin in all the extracts. The analysis of volatile substances developed by SPME-GC/MS promoted the identification of two compounds found only in the honeydew samples. The compounds were the terpinen-4-ol, which has antifungal, antiparasitological and anti-inflammatory activities; and 3,4-dimethyl-1-decene. Both compounds can be used as chemical markers of these honeys. The knowledge of the chemical composition of the studied honeys, as well as their bioactive phenolic composition, contributes to supply natural antioxidants to human diet, thus attenuating the negative effects of free radicals
|
608 |
Etude du procédé de co-pyrolyse de déchets plastiques et d’huiles de lubrification usagées dans le but de produire un combustible liquide alternatifBreyer, Sacha 14 October 2016 (has links)
Cette étude s’inscrit dans le cadre du projet MINERVE de la région wallonne quivise notamment à valoriser les anciens centres d’enfouissement technique et leur contenuau travers de la production de matières premières et de sources d’énergie. Plus particulièrement,l’objectif de ce travail est d’étudier un procédé de co-pyrolyse de déchetsplastiques et d’huiles de lubrification usagées, ayant pour finalité la production d’uncombustible alternatif liquide pour l’industrie, en vue d’une future montée en échelledu procédé.Pour ce faire, différentes approches ont été poursuivies. Premièrement, nous avonsmis en place un réacteur de 5 litres, agité et scellé hermétiquement, permettant demener des essais de co-pyrolyse. Des essais de co-pyrolyse d’un mélange de déchetsplastiques excavés et d’huiles de lubrification usagées ont été menés dans le réacteur.L’influence des paramètres clés du procédé, tels que la température maximale, la fractionmassique de plastiques dans le mélange ainsi que la vitesse de refroidissement, surle procédé et la qualité du produit fini a été étudiée. Nous avons été en mesure deproduire un combustible alternatif liquide, possédant un pouvoir calorifique d’environ30 MJ/kg, par la co-pyrolyse d’un mélange contenant 60% de plastiques, en chauffantle mélange durant 13 h, en atteignant une température maximale de 387°C et enlaissant la pression au sein du réacteur monter jusqu’environ 30 bars. Les besoins énergétiquesdu procédé ont été évalués à environ 8 MJ/kg de déchets à pyrolyser, grâce àun modèle de transferts thermiques développé pour le système constitué du réacteur deco-pyrolyse. Ensuite, une méthode a été développée pour déterminer le temps de fonted’une particule de plastique en fonction de sa plus petite dimension. L’application decette méthode nous a permis de déterminer que la plus petite dimension maximale quepeuvent avoir les particules de plastiques dans le mélange plastique/huile, pour queleur fusion ne limite pas le procédé de co-pyrolyse, est d’environ 3 cm. Deux analysesthermiques, la thermogravimétrie isotherme et la calorimétrie différentielle à balayage,ont été combinées pour caractériser le craquage thermique et son influence sur plusieurspolymères. L’influence du craquage thermique sur les polymères a été évaluée sur basede l’analyse de la fusion ou de la transition vitreuse du polymère. Les protocole et dispositifexpérimentaux de co-pyrolyse de déchets plastiques et d’huiles de lubrificationusagées à l’échelle du laboratoire ont été adaptés pour pouvoir co-pyrolyser un mélangecontenant du PVC. Différents essais de co-pyrolyse par étapes ont été menés pour évaluerl’influence des paramètres comme l’évolution de la température pendant l’essai, lecontenu en PVC du mélange et le plastique en mélange avec le PVC (LDPE ou PS).Enfin, les interactions qui prennent place entre le LDPE ou le PS et une huile, lorsde leur co-pyrolyse, ont été mises en évidence à l’aide d’essais de thermogravimétriehaute résolution. Nous avons tenté d’expliquer les interactions mises en évidence, grâceà une combinaison d’analyses thermiques permettant de caractériser, voire d’identifier,les produits de décomposition de l’échantillon, en continu ou en fin de chauffe.This study takes part in the MINERVE (Walloon region) which aims at enhancingthe old landfills and valorize their content through the production of raw materials andenergy sources. Specifically, the objective of this work is to study a co-pyrolysis processof waste plastics and used lubrication oils, whose purpose is the production of a liquidalternative fuel for industry, in order to future scaling up the process.To do so, different approaches have been pursued. First, we set up a 5 liter reactor,stirred and hermetically sealed for performing co-pyrolysis tests. Co-pyrolysis tests ofa mixture of excavated plastic wastes and used lubrication oils were performed in thereactor. The influence of key parameters, such as maximum temperature, the massfraction of plastics in the mixture and the cooling rate, on the process and the qualityof the fuel was investigated. We were able to produce a liquid alternative fuel, witha calorific value of about 30 MJ/kg by co-pyrolyzing a mixture containing 60 % ofplastic, heating the mixture for 13 h, reaching a maximum temperature of 387°C anda maximum pressure of about 30 bar. The energy requirements of the process wereevaluated at about 8 MJ per kg of waste through a heat transfer model developed forthe system consisting of the co-pyrolysis reactor. In addition, a method was developedto determine the time of melting of a plastic particle according to its smallest size.The application of this method allowed us to determine that the maximum smallestsize that can have plastic particles in plastic/oil mixture, so that their melting willnot limit the co-pyrolysis process, is about 3 cm. Two thermal analysis techniques,isothermal thermogravimetry and differential scanning calorimetry, were combined tocharacterize the thermal cracking and its influence on several polymers. The influence ofthermal cracking of the polymers was evaluated based on the analysis of the melting orglass transition of the polymer. The experimental protocol and device of waste plasticsand used lubricating oils co-pyrolysis have been adapted to co-pyrolyze a mixturecontaining PVC. Two-step co-pyrolysis tests were performed to evaluate the influenceof parameters such as the evolution of the temperature during the test, the PVCcontent of the mixture and the plastic that is mixed with PVC (LDPE or PS). Finally,interactions that take place between the LDPE or the PS and an oil, when co-pyrolyzed,have been identified with high resolution thermogravimetry experiments. We tried toexplain the identified interactions through a combination of thermal analyzes thatcharacterized or identified the sample decomposition products, continuously duringthe thermal decomposition or at its end. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished
|
609 |
Evaluation of Non-Contact Sampling and Detection of Explosives using Receiver Operating Characteristic CurvesYoung, Mimy 07 November 2013 (has links)
The growing need for fast sampling of explosives in high throughput areas has increased the demand for improved technology for the trace detection of illicit compounds. Detection of the volatiles associated with the presence of the illicit compounds offer a different approach for sensitive trace detection of these compounds without increasing the false positive alarm rate. This study evaluated the performance of non-contact sampling and detection systems using statistical analysis through the construction of Receiver Operating Characteristic (ROC) curves in real-world scenarios for the detection of volatiles in the headspace of smokeless powder, used as the model system for generalizing explosives detection. A novel sorbent coated disk coined planar solid phase microextraction (PSPME) was previously used for rapid, non-contact sampling of the headspace containers. The limits of detection for the PSPME coupled to IMS detection was determined to be 0.5-24 ng for vapor sampling of volatile chemical compounds associated with illicit compounds and demonstrated an extraction efficiency of three times greater than other commercially available substrates, retaining >50% of the analyte after 30 minutes sampling of an analyte spike in comparison to a non-detect for the unmodified filters. Both static and dynamic PSPME sampling was used coupled with two ion mobility spectrometer (IMS) detection systems in which 10-500 mg quantities of smokeless powders were detected within 5-10 minutes of static sampling and 1 minute of dynamic sampling time in 1-45 L closed systems, resulting in faster sampling and analysis times in comparison to conventional solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) analysis. Similar real-world scenarios were sampled in low and high clutter environments with zero false positive rates. Excellent PSPME-IMS detection of the volatile analytes were visualized from the ROC curves, resulting with areas under the curves (AUC) of 0.85-1.0 and 0.81-1.0 for portable and bench-top IMS systems, respectively. Construction of ROC curves were also developed for SPME-GC-MS resulting with AUC of 0.95-1.0, comparable with PSPME-IMS detection. The PSPME-IMS technique provides less false positive results for non-contact vapor sampling, cutting the cost and providing an effective sampling and detection needed in high-throughput scenarios, resulting in similar performance in comparison to well-established techniques with the added advantage of fast detection in the field.
|
610 |
The Skeletal Amino Acid Composition of the Marine Demosponge Aplysina cavernicolaUeberlein, Susanne, Machill, Susanne, Niemann, Hendrik, Proksch, Peter, Brunner, Eike 07 May 2015 (has links)
It has been discovered during the past few years that demosponges of the order Verongida such as Aplysina cavernicola exhibit chitin-based skeletons. Verongida sponges are well known to produce bioactive brominated tyrosine derivatives. We could recently demonstrate that brominated compounds do not exclusively occur in the cellular matrix but also in the skeletons of the marine sponges Aplysina cavernicola and Ianthella basta. Our measurements imply that these yet unknown compounds are strongly, possibly covalently bound to the sponge skeletons. In the present work, we determined the skeletal amino acid composition of the demosponge A. cavernicola especially with respect to the presence of halogenated amino acids. The investigations of the skeletons before and after MeOH extraction confirmed that only a small amount of the brominated skeleton-bound compounds dissolves in MeOH. The main part of the brominated compounds is strongly attached to the skeletons but can be extracted for example by using Ba(OH)2. Various halogenated tyrosine derivatives were identified by GC-MS and LC-MS in these Ba(OH)2 extracts of the skeletons.
|
Page generated in 0.0442 seconds