Tesis sobre el tema "Aliments – Teneur en polluants"
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Choueiri, Joanna. "Évaluation des expositions humaines aux polluants de l'environnement par l'alimentation". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALS005.
Texto completoThe main challenges related to nutrition include ensuring an optimal diet, ensuring a good environmental impact of the food system, and ensuring food safety for consumers, including exposure to chemicals, especially since food is a major source of exposure to environmental pollutants for the general population. Consequently, this thesis embarks on a comprehensive analysis to address these challenges at the following levels: To meet the environmental and food safety challenges, through the development and implementation of a methodology to assess the impact of organic food consumption versus conventional food on consumer exposure to environmental pollutants in Europe, and to meet the challenge of ensuring an optimal diet for all, through the assessment of the nutritional quality of University Grenoble Alpes (UGA) students via a score based on the national nutrition program in France (PNNS) while studying the impact of food insecurity on adherence to national dietary recommendations. To achieve these objectives, a comprehensive database was first created to collect data from the literature on contamination levels in organic agriculture in Europe, as no exhaustive databases exist in the literature. Then, since the data from the database had limitations (quantitative and unit limitations) that prevented the direct calculation of exposure levels from the available data, an Excess Ratio (ER) approach was developed that first allowed the evaluation of the chemical content between different agricultural foods and served as the basis for the methodology to assess the impact of organic food consumption on the level of exposure to chemicals compared to conventional foods. Further, a population of UGA students was selected and assessed using a score developed based on the PNNS, and the association between food insecurity and adherence to the PNNS was examined. The dietary exposure profile of the students was assessed using the French Total Diet Study (EAT2) contamination database for selected substances and the developed methodology for assessing the impact of organic food consumption was applied to this population. As the students showed a level of concern for dimethoate, cadmium, lead, inorganic arsenic, nickel and dioxins, the impact of organic food consumption on the level of exposure to these substances was inconclusive. In terms of dietary quality, the overall compliance rate with the PNNS guidelines was 62%, with food insecure students showing lower compliance for fruits and vegetables (p = 0.004), alcohol (p = 0.005) and higher compliance for meat, poultry, and eggs (p = 0.021) and whole grains (p = 0.01). This thesis has provided a method that is universal and overcomes all the limitations of the currently available data, allowing the evaluation of the effect of organic food consumption. This thesis also serves as an illustrative example of a multifaceted research that addresses numerous challenges related to dietary practices
Cabanis, Marie-Thérèse. "Contribution a l'étude du dosage des éléments traces dans les aliments par absorption atomique sans flamme : cas particulier du cadmium". Montpellier 1, 1985. http://www.theses.fr/1985MON13507.
Texto completoLaberge-Carignan, Audrey y Audrey Laberge-Carignan. "Élaboration d'une stratégie analytique de dissolution du Hg et du Pb dans les aliments sur le terrain". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38101.
Texto completoLa nourriture issue de la chasse ou de la pêche comporte plusieurs nutriments essentiels à une bonne santé. Toutefois ces aliments peuvent aussi contenir des concentrations importantes en contaminants tel que le mercure et le plomb, qui posent un risque pour la santé. Pour guider les communautés qui basent leur alimentation sur la chasse ou la pêche, l’objectif global du projet est de développer une plateforme analytique permettant le suivi de la qualité alimentaire dans les environnements nordiques. Pour ce faire, une stratégie analytique de dissolution de la chair animale pouvant être employée à l’extérieur d’un laboratoire par des non scientifiques a été mise en place. Cette stratégie comporte l’échantillonnage, la mise en solution de la chair et la séparation des analytes pour effectuer leur analyse ainsi que le changement de matrice, en plus de la détection et de la quantification des analytes par fluorimétrie. Toutefois, puisque les systèmes de détection visés pour la plateforme sont en développement, une méthode de quantification du plomb et du mercure par ICP-MS/MS a aussi été développée. Cette stratégie analytique a été élaborée pour l’analyse de l’omble chevalier, un poisson consommé à l’année dans certaines communautés nordiques dans lequel les concentrations en contaminants sont très variables. Le processus analytique, de l’échantillonnage à l’obtention d’une solution mono élémentaire en passant par l’analyse ICP-MS/MS et la dissolution de la chair d’omble chevalier, sera décrit dans ce mémoire.
Fish and game meat contain different essential nutriments for a good health. However, it can also contain contaminants, such as mercury and lead, that pose a health risk. To guide the communities that base their diet on hunting or fishing, the main objective of the project is to develop a portable analytical platform that allows the monitoring of contamination by heavy metals of country food on the field. To this end, an analytical strategy for the dissolution of food flesh that can be deployed outside of the laboratory and used by non-scientists has been established. This strategy includes sampling, flesh dissolution, analyte separation and matrix exchange for the analysis in addition to fluorimetric detection and quantitation of the analytes. Since the quantification system for this platform is still under development, we therefore developed an ICP-MS/MS method to quantify lead and mercury in our food extracts. This method was developed to analyze arctic char, a fish consumed all year long in some northern communities and in which the contamination level can vary significantly. The analytical process from sampling to monoelemental analysis by ICP-MS/MS will be discussed in this document.
Fish and game meat contain different essential nutriments for a good health. However, it can also contain contaminants, such as mercury and lead, that pose a health risk. To guide the communities that base their diet on hunting or fishing, the main objective of the project is to develop a portable analytical platform that allows the monitoring of contamination by heavy metals of country food on the field. To this end, an analytical strategy for the dissolution of food flesh that can be deployed outside of the laboratory and used by non-scientists has been established. This strategy includes sampling, flesh dissolution, analyte separation and matrix exchange for the analysis in addition to fluorimetric detection and quantitation of the analytes. Since the quantification system for this platform is still under development, we therefore developed an ICP-MS/MS method to quantify lead and mercury in our food extracts. This method was developed to analyze arctic char, a fish consumed all year long in some northern communities and in which the contamination level can vary significantly. The analytical process from sampling to monoelemental analysis by ICP-MS/MS will be discussed in this document.
Harfouch, Muhssen. "Etude expérimentale et modélisation des phénomènes de diffusion et de modification de texture des fromages de type Feta conservés en saumure". Vandoeuvre-les-Nancy, INPL, 1990. http://www.theses.fr/1990INPL090N.
Texto completoJoannis, Claire. "Médicaments et leurs résidus dans les aliments". Paris 5, 1992. http://www.theses.fr/1992PA05P206.
Texto completoNasreddine, Lara. "Nouvelles données en sécurité sanitaire des aliments au Liban : Définition du panier de la ménagère Beyrouthin : Evaluation de la contamination des aliments en radionucléides : Evaluation de l'exposition aux métaux lourds par voie alimentaire". Brest, 2005. http://www.theses.fr/2005BRES2010.
Texto completoThe present study is the first in Lebanon to evaluate, by the market basket approach, the contamination of foods by radionuclides and heavy metals and the dietary exposure of the Lebanese population to the heavy metals Pb, Cd and Hg. An individual dietary survey has been realized on 444 adult individuals living in Beirut. Food consumption data were collected using a quantitative food frequency questionnaire. The market basket was identified by selecting those foods with a mean daily intake exceeding 1g/day. The contamination levels of the selected foods with heavy metals and radionuclides were assessed. The results show that the level of radioactivity of the analyzed food does not present any concern for public health. The average dietary exposure of the average individual to Pb, Cd, and Hg corresponds to 7,17 and 6 % of the respective PTWIs. This permits to conclude that, for the average individual, there is no risk of exceeding the PTWIs
Laberge-Carignan, Audrey. "Élaboration d'une stratégie analytique de dissolution du Hg et du Pb dans les aliments sur le terrain". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38101.
Texto completoFish and game meat contain different essential nutriments for a good health. However, it can also contain contaminants, such as mercury and lead, that pose a health risk. To guide the communities that base their diet on hunting or fishing, the main objective of the project is to develop a portable analytical platform that allows the monitoring of contamination by heavy metals of country food on the field. To this end, an analytical strategy for the dissolution of food flesh that can be deployed outside of the laboratory and used by non-scientists has been established. This strategy includes sampling, flesh dissolution, analyte separation and matrix exchange for the analysis in addition to fluorimetric detection and quantitation of the analytes. Since the quantification system for this platform is still under development, we therefore developed an ICP-MS/MS method to quantify lead and mercury in our food extracts. This method was developed to analyze arctic char, a fish consumed all year long in some northern communities and in which the contamination level can vary significantly. The analytical process from sampling to monoelemental analysis by ICP-MS/MS will be discussed in this document.
Gobet, Mallory. "Etude par spectroscopies de RMN 23Na , 31P et 1H : effets de la teneur en sel (NaCl) dans des matrices alimentaires". Dijon, 2008. http://www.theses.fr/2008DIJOS063.
Texto completoThe reduction of salt (NaCl) content in food has become a matter of public health. However, the multiple functions of salt in food make the reduction of its content difficult. The aim of this work was to demonstrate the applicability of NMR innovative techniques in order to characterise the mobility of sodium ions (distinction between ‘free’ and ‘bound’ sodium), to bring a better understanding of the role of salt in the organisation of the food matrix (in particular phosphorous molecules in dairy systems) and to study impact of salt on the mobility of aroma compounds. In a first step, the 23Na NMR study of iota-carrageenan gels validated the quantification of total sodium (Single-Quantum, SQ experiment) and also demonstrated the involvement of ‘bound’ sodium ions in the gelation process of this polysaccharide (Double-Quantum Filtered, DQF experiment). The diffusion of aroma compounds in these systems was measured by 1H DOSY NMR, but no specific impact of salt was evidenced. The second step was dedicated to study dairy systems and semi-hard cheeses by 23Na NMR and solid-state 31P NMR using the magic angle spinning (MAS) technique. We demonstrated the feasibility of 23Na NMR methods for the quantification of total sodium and the characterisation of Na motional state (presence of ‘bound’ ions) in these systems. 31P MAS NMR (simple pulse excitation, SPE and cross-polarisation, CP) enabled the identification of different phosphorous compounds (inorganic phosphate, colloidal calcium phosphate, phosphoserins), the determination of their proportions and also permitted to determine the involvement of these phosphorous compounds in the protein network of coagulated systems. With these results, we achieved to identify the parameters of composition (or processing) influencing the dynamics of sodium ions in real cheeses. We also determined the distribution of phosphorous compounds, in particular inorganic phosphate, in these cheeses. This work demonstrates that these 23Na and 31P NMR innovative techniques are perfectly applicable to real food and can help to adjust the manufacturing process of cheeses in order to optimise their sensory and functional properties
Yahyaoui, Mohammed. "Etude cinétique de la formation de polluants à partir de mélanges représentatifs des essences". Orléans, 2005. http://www.theses.fr/2005ORLE2024.
Texto completoDuffour, Jacqueline. "Résidus des dithiocarbamates et de l'éthylènethiourée : aspects toxicologiques et analytiques". Montpellier 1, 1991. http://www.theses.fr/1991MON13511.
Texto completoPaquin, Julie. "Étude de l'effet de la consommation d'un jus enrichi en fibres alimentaires sur la satiété et la réponse glycémique". Thesis, Université Laval, 2008. http://www.theses.ulaval.ca/2008/25243/25243.pdf.
Texto completoEl-Bidaoui, Maha. "L'effet de la procédure analytique sur les résidus des pesticides dans les aliments". Aix-Marseille 3, 2002. http://www.theses.fr/2002AIX30068.
Texto completoThe components of typical procedures for pesticide residues analysis to determine their uncertainty are studied. Procedures for the evaluation of the efficiency and the uncertainty of sample processing, extraction, clean up and determination are developed based on radiotracer and chromatographic techniques with representative foodstuffs and analytes. Sample processing uncertainty is evaluated based on the determination of the 14C activities from test portions of different sizes and estimation of the sampling constants. Different procedures are investigated to decrease the uncertainty of sample processing. A significant finding was that the efficiency of processing varied with the type of equipment and foodstuffs. A synergistic effect was observed by double processing with addition of dry ice. A methodology is developed to study the effects of processing and storage on the pesticide residues' stability. The efficiency and uncertainty of the clean up are studied at different temperatures. The quantification procedures showed that the associated uncertainty is a major contributor to the overall uncertainty and is dependent upon the regression model
Floch, Carine. "Les enzymes du sol : étude de leurs potentialités bioindicatrices de contaminations par des métaux et des polluants organiques". Aix-Marseille 3, 2008. http://www.theses.fr/2008AIX30070.
Texto completoThe main objective of this research was to determine the potential bioindicator of certain enzymatic activities to characterize the functioning and quality of soil in the context of metal and organic pollutions (i. E. Pesticides and conventional, organic or biological, and integrated management strategies). In a first step, a methodology for the quantification in soils of phenol oxidase activities has been developed, and further study on its sensitivity towards certain metals has been performed. Thereafter, different approaches have been apprehended through incubation under controlled laboratory conditions and field observations, made at scales ranging from plot to landscape. The enzymes studied are involved in the functioning of the major biogeochemical cycles of C (cellulase, fluorescein diacetate hydrolase, β-galactosidase, β-glucosidase and phenol oxidase), N (arylamidase), P (acid and alkaline phosphomonoesterases, phosphodiesterase and phosphotriesterase) and S (arylsulfatase). The results have clearly demonstrated the variability of response patterns of enzyme activities, with the type of contamination and physical and chemical characteristics of soils. This underlines the difficulty for selecting universal enzymatic bioindicators of soil quality for a wide range of perturbations. However, some enzymes, such as arylamidases and phenol oxidases, proved repeatedly to be indicators especially sensitive to disturbance applied to the different soils of this study. An interesting continuation of this work would be to integrate such kind of study of these potential bioindicators in networks of soil quality measurement. Finally, other microbial parameters were also studied, the functional diversity of bacterial communities (Biolog® Eco) and bacterial and fungal densities, but they have proved to be less relevant as soil quality indicators with regards to enzyme activities
Béguin, Sylvie. "Développement d'une méthode d'optimisation des conditions de détection GC/EI/MS/MS à l'aide d'un piège ionique quadripolaire : application au dosage multi-résidus de pesticides". Angers, 2002. http://www.theses.fr/2001ANGE0016.
Texto completoArnaud, Nicole. "Composition minérale des baies de raisins frontonnais : influence des cépages, des porte-greffes, du sol et du climat". Toulouse 3, 1987. http://www.theses.fr/1987TOU32123.
Texto completoLarauche, Muriel. "Régulations des processus inflammatoires gastriques : rôle des nitrates alimentaire et de l'innervation afférente". Toulouse 3, 2003. http://www.theses.fr/2003TOU30100.
Texto completoNouvel, Cécile. "Synthèse contrôlée de copolymères dextrane-g-polylactide : de leur utilisation comme surfactifs biodégradables à la mise en œuvre de systèmes de vectorisation particulaires". Vandoeuvre-les-Nancy, INPL, 2002. http://docnum.univ-lorraine.fr/public/INPL_T_2002_NOUVEL_C.pdf.
Texto completoSynthesis of novel grafted amphiphilic copolymers polylactide-grafted dextran was achieved. Macromolecular control of such biodegradable and potentially biocompatible copolymers requires a three-step synthesis based on the "grafting from" concept : partial protection of the dextran hydroxyl groups by silylation ; followed by ring opening polymerization of D, L-lactide initiated from remaining hydroxyls of this partially silylated dextran backbone. The third step involves the silylethers deprotection under very mild conditions. Throughout the synthesis, detailed studies of each step have led to stability of dextran backbone and control of copolymer architecture in terms of graft number and graft length. Tension and fluorescence experiments have given information about the organisation properties of these copolymers. The potential of such copolymers for formulation of nanospheres has been also studied
Heimbürger, Lars-Éric. "Dynamics of chemical contaminants in the open ocean : the Mediterranean sea as an example". Nice, 2010. http://www.theses.fr/2010NICE4014.
Texto completoCe travail est une investigation de la dynamique des transports, transferts et transformations de contaminants chimiques (CCs) dans un système océanique ouvert via une approche intégrative des sources vers les réservoirs, nommément de l’atmosphère jusqu’au sédiment. La stratégie d’observation a été construite de manière à tenir compte de variations saisonnières conditionnant la pompe biologique. Les apports atmosphériques, qui constituent la source principale des CCs pour les eaux marines en Mer Ligure ont été suivis au site de référence de Cap Ferrat (SE France). Parallèlement, des échantillonnages mensuels ont été effectués dans la colonne d’eau (site DYFAMED, entre Nice et la Corse) afin de suivre l’évolution des CCs et des paramètres physiques et biogéochimiques en phase dissoute et particulaire pendant près de 2 ans. Des mouillages de pièges à particules ont permis d’étudier le flux exportés. Une carotte de sédiment a été prélevée afin d’estimer le niveau d’anthropisation. Des métaux traces (Al, Cd, Co, Cu, Hg, MeHg, Ni and Pb) et contaminants organiques persistants (PBDEs, PCBs and PAHs) ont été déterminés dans chaque matrice afin d’observer les variations saisonnières et d’élucider les relations entre les apports atmosphériques et la réponse environnementale. Une attention particulière a été portée à la définition des sources, aux tendances, au transfert vertical, au recyclage et au devenir ultime des CCs. Nous concluons que la dynamique des CCs dans un tel milieu est fortement influencée par le forçage physique. Ceci a pour conséquence que toute altération du climat aura, via la production biologique, des conséquences sur la dynamique des CCs
Zervas, Efthimios. "Etude des mécanismes de formation des polluants spécifiques émis par les moteurs à combustion interne". Mulhouse, 1996. https://tel.archives-ouvertes.fr/tel-02966575.
Texto completoMethods for the analysis on sulfur dioxide, alcohols and organic acids have been developed. The first one includes the capture of the sulfur dioxide in a solution of oxygenated water and the analysis by ionic chromatography with a conductimetric detector. The second one includes the capture in pure water and an analysis by gas chromatography/flame ionisation detector. The third one uses the capture in pure water and the analysis of the formic acid by an ionic chromatography and of the other acids by gas chromatography. These methods have been applied in the case of vehicles' non-regulated pollutants research. An experiment design, combined specified fuels and analysis of the exhaust gazes, has been applied on a spark ignition engine. These tests proved several qualitative and quantitative correlations between the composition of the fuel and the emitted pollutants. Precursors of hydrocarbons, aldehydes, ketones, alcohols and organic acids have been found. These results show that aromatics and cyclohexane contribute for the benzene's formation, 1-hexene and cyclohexane for the 1,3 butadiene's, aromatics are the precursors of the propionic acid and o xylene of the butyric acid
Barchechath, Jérémie y Jérémie Barchechath. "Étude du potentiel nutraceutique des fibres de canneberge et de bleuet". Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25348.
Texto completoLes résidus fibreux de canneberge et de bleuet issus du processus d’extraction des polyphénols ont été étudiés pour tenter de les valoriser pour des applications nutraceutiques. Ces travaux se sont plus précisément intéressés aux fibres alimentaires et à leurs polyphénols associés. Ces deux composantes sont reconnues pour leurs effets positifs sur le système digestif dont notamment le maintien de la santé de la flore intestinale. Les résidus fibreux de canneberge et de bleuet obtenus en laboratoire ont été caractérisés pour leurs contenus en polysaccharides non-amidonnés totaux (54,3% pour la canneberge et 46,5% pour le bleuet), solubles (respectivement 21,9% et 21,5%), insolubles (respectivement 32,4% et 25%) et leurs compositions respectives en monosaccharides. Les mesures rhéologiques des fibres (capacité de rétention d’eau, d’huile, capacité de gonflement et viscosité) ont montré des propriétés physiques avantageuses en comparaison à d’autres types de fibres. Le contenu en proanthocyanidines non-extractibles fut alors mesuré par lecture spectrophotométrique (1,3% pour les fibres de canneberge et 2,4% pour celles de bleuet). Une technique utilisant un agent chaotrope fut spécifiquement développée pour obtenir une fraction significativement réduite en polyphénols (contenant respectivement 0,6% et 0,9% de proanthocyanidines). Les fibres brutes et réduites en polyphénols ont alors été administrées à des souris pour tester leurs impacts respectifs sur la flore intestinale. L’ajout de fibres brutes a fait augmenter la concentration de Clostridium coccoides et de Clostridium leptum et diminuer le compte de Lactobacillus alors que celui de Faecalibacterium praunsnitzii a uniquement augmenté avec les fibres réduites en polyphénols mettant en avant un probable effet inhibiteur des polyphénols sur F. prausnitzii. Des souches probiotiques ont alors été cultivées in vitro avec des fibres natives et réduites en proanthocyanidines. Un effet bifidogène ainsi qu’une augmentation de la croissance de Lactobacillus salivarius ont été observés lors de l’ajout de fibres de canneberge et de bleuet. Selon le type de bactérie, les effets différentiels observés avec les fibres brutes ou réduites en proanthocyanidines montrent la capacité de la flore à métaboliser les polysaccharides et leurs polyphénols associés mais aussi un potentiel effet inhibiteur des composés phénoliques. Les fibres de canneberge et de bleuet pourraient ainsi constituer des prébiotiques favorisant indirectement la réduction du risque lié à certaines maladies chroniques intestinales.
The process of polyphenol extraction from cranberry and blueberry yields a fibrous matter that was studied for a potential valorization in nutraceutical applications. More precisely, this work focuses on the dietary fiber content and its associated polyphenols. These two compounds were acknowledged for their positive effects over the gastro-intestinal tract including the preservation of a healthy colonic microbiota. The polyphenol extraction process was replicated in laboratory in order to obtain cranberry and blueberry fibrous matter. These extracts were analysed for their contents in total non-starch polysaccharides (NSP) (54,3% for cranberry and 46,5% for blueberry), soluble NSP (respectively 21,9% and 21,5%), insoluble NSP (respectively 32,4% and 25%) and their respective monosaccharides composition. Rheological measurements (water and oil retention capacities, swelling capacity and viscosity) showed advantageous physical properties compared to other types of fibers. Subsequently, the non-extractable proanthocyanidins contents were quantified by spectrophotometric reading (1,3% for cranberry fibers and 2,4% for blueberry fibers). A method, employing a chaotropic agent, was specifically designed to produce fibers with a significantly reduced content in non-extractable proanthocyanidins (respectively containing 0,6% and 0,9% of PAC). Both native and modified fibers were fed to mice in order to assess their respective impact on intestinal flora. The addition of native fibers was associated with an increase in the concentration of Clostridium coccoides and Clostridium leptum and a diminution of the count of Lactobacillus whereas the concentration of Faecalibacterium praunsnitzii was exclusively increased by the use of fibers reduced in polyphenols. This observation highlighted a potential inhibitory effect of polyphenols on F. prausnitzii. Probiotics strains were therefore cultured in vitro with native and modified fibers. A bifidogenic effect and an increase of the Lactobacillus salivarius concentration were observed when substrate was cranberry or blueberry fibers. According to the type of bacteria, the differential effect monitored between native and proanthocyanidins reduced fibers underlies the flora capacity to metabolize fibers and their associated polyphenols and also a potential inhibitory effect from phenolic compounds. The cranberry and blueberry fibers could therefore constitute prebiotics that favor indirectly the reduction of gastro-intestinal diseases risks.
The process of polyphenol extraction from cranberry and blueberry yields a fibrous matter that was studied for a potential valorization in nutraceutical applications. More precisely, this work focuses on the dietary fiber content and its associated polyphenols. These two compounds were acknowledged for their positive effects over the gastro-intestinal tract including the preservation of a healthy colonic microbiota. The polyphenol extraction process was replicated in laboratory in order to obtain cranberry and blueberry fibrous matter. These extracts were analysed for their contents in total non-starch polysaccharides (NSP) (54,3% for cranberry and 46,5% for blueberry), soluble NSP (respectively 21,9% and 21,5%), insoluble NSP (respectively 32,4% and 25%) and their respective monosaccharides composition. Rheological measurements (water and oil retention capacities, swelling capacity and viscosity) showed advantageous physical properties compared to other types of fibers. Subsequently, the non-extractable proanthocyanidins contents were quantified by spectrophotometric reading (1,3% for cranberry fibers and 2,4% for blueberry fibers). A method, employing a chaotropic agent, was specifically designed to produce fibers with a significantly reduced content in non-extractable proanthocyanidins (respectively containing 0,6% and 0,9% of PAC). Both native and modified fibers were fed to mice in order to assess their respective impact on intestinal flora. The addition of native fibers was associated with an increase in the concentration of Clostridium coccoides and Clostridium leptum and a diminution of the count of Lactobacillus whereas the concentration of Faecalibacterium praunsnitzii was exclusively increased by the use of fibers reduced in polyphenols. This observation highlighted a potential inhibitory effect of polyphenols on F. prausnitzii. Probiotics strains were therefore cultured in vitro with native and modified fibers. A bifidogenic effect and an increase of the Lactobacillus salivarius concentration were observed when substrate was cranberry or blueberry fibers. According to the type of bacteria, the differential effect monitored between native and proanthocyanidins reduced fibers underlies the flora capacity to metabolize fibers and their associated polyphenols and also a potential inhibitory effect from phenolic compounds. The cranberry and blueberry fibers could therefore constitute prebiotics that favor indirectly the reduction of gastro-intestinal diseases risks.
Durand, Cédric. "Caractérisation physico-chimique des produits de l'assainissement pluvial : origine et devenir des métaux traces et des polluants organiques". Poitiers, 2003. http://www.theses.fr/2003POIT2287.
Texto completoThe objective of this multidisciplinary work was to characterise the mineral and organic matters in the sediments from storm water drainage systems. Several physical chemical techniques were used to study the mineral fraction of sediments from retention ponds and street sweeping. This study concerned major elements and trace metals. The results show that the sediments are often polluted, with concentrations higher than the reference values for polluted soils. The study of organic matter shows that the lipid fractions are mainly composed of hydrocarbons and PAHs at high concentrations. Humic acids and humine were studied by global techniques and by thermochimiolysis with different alkyl agents. The TMAH technique shows that the studied humic substances contain biopolymers from plant and bacterial origins, as well as ligneous fibres. The use of TEAA allows to show that the released compounds are partly trapped in the humic macromolecular net and are released as soon as this one is altered. The last part of the work was devoted to trace metal mobility in the different organic fractions and using the BCR sequential extraction scheme. The mobility sequence of trace metals appears to be : Cr £ Ni < Pb £ Cu < Zn £ Cd. These results could be used as a basis for recommendations to local governments in order to improve the management of sediments from storm water drainage systems
Abed, Aïcha. "Nouveaux dispositifs médicaux à base d'hydrogels de polysaccharides". Paris 13, 2012. http://www.theses.fr/2012PA132062.
Texto completoThis work describes the development of new medical devices based on hydrogel of polysaccharides (pullulan and dextran). In recent years, our laboratory was interested in the biological properties of synthetic or natural polysaccharides and their interactions with endogenous growth factors and matrix components. So we had the idea to apply their properties to the design of a hybrid material composed of a polypropylene mesh coated with polysaccharides hydrogel. The first objective of this work is to improve the integration of materials currently used in clinical by using of hybrid prosthesis and understand the properties of these hydrogels in vitro and in vivo. In the second part of this work, based on the hydrogel properties a new system of storage and transport of tissue at room temperature was developed while limiting mechanical shocks and contamination associated with leaking fluids. Taking as a model of rat arteries, we validated this system in vitro and in vivo. Finally, we developed a new system for cryopreservation of cells and tissues. This hydrogel based polysaccharides reduces the quantities of toxic cryoprotectants agents during freezing. This method was validated in vitro and in vivo and in comparison with the reference procedure
Raouche, Sana. "Dynamique d’organisation des micelles de caséine et de structuration des gels laitiers : vectorisation de minéraux". Montpellier 2, 2007. http://www.theses.fr/2007MON20226.
Texto completoIron deficiency is the most frequent nutritional disorder with serious consequences on physical and mental health at individual and nation levels. The aim of the PhD was to solve the technological problems involved in the iron fortification of the dairy products. The work firstly lay in the optimization of the carbonation process and thus in the use of milk as iron vehicle. The reversible acidification process by CO2 injection was studied and optimized. This process, without modifying milk ionic strength, brings elements of comprehension with regard to the dynamic of caseins micelles organization and dairy gel structuring. Micellar calcium phosphate (MCP) reorganization is governed by the carbonation pH, while caseins organization depends on the temperature of treatment. On opposite to enzymatic gelation, “acid” curd formation depends neither on the MCP salt form, nor on caseins organization within micelles in the range of carbonation parameters studied. Reconstituted skimmed milks fortified with FeCl2 and FeCl3 up to 20mmol Fe/kg and subjected or not to carbonation were studied within one day of storage at 30°C. 57Fe Mössbauer spectrometry shows that iron is involved in octahedral coordination with Pi and Po. The carbonation (i) improves the binding yield of iron to casein micelles (ii) the milk rennet clotting time, and (iii) accelerates Fe2+ oxidation. Bioavailability evaluation results are promising but have to be handled with caution
Charon, Hélène. "Détection et quantification d'ajouts de matière grasses végétales autres que le beurre de cacao dans le chocolat". Université Louis Pasteur (Strasbourg) (1971-2008), 2005. http://www.theses.fr/2005STR13119.
Texto completoYamada, Ami. "Evaluation de l'exposition agrégée aux PFAA, mise en regard des expositions externe et interne". Nantes, 2015. http://www.theses.fr/2015NANTA65F.
Texto completoYamada, Ami. "Evaluation de l'exposition agrégée aux PFAA, mise en regard des expositions externe et interne". Nantes, Ecole nationale vétérinaire, 2015. http://www.theses.fr/2015ONIR065F.
Texto completoFournier, Agnès. "Transfert de Polluants Organiques Persistants (POP) vers l’œuf de poule : influence des caracteristiques des polluants et du statut physiologique de l’animal". Electronic Thesis or Diss., Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL031N.
Texto completoLaying hens are likely to be exposed to a wide range of persistent organic pollutants (POPs) potentially present in their environment. In the context of securing poultry farming systems regarding POPs, our research has focused on identifying and grading factors likely to influence the transfer of ingested POPs to eggs. These factors are related to the nature of the ingested matrix (soil or feed), to the characteristics of the animal (laying rate, fatness) and to the properties of the molecule (lipophilicity, sensitivity to metabolism). Different scientific approaches have been implemented: in vivo experimentation and mathematical modeling. In the frame of in vivo experiments we have assessed the relative bioavailability of PCBs from one naturally contaminated soil. In addition, we have calculated parameters of the kinetics of transfer to eggs of molecules that had never been studied in laying hens, such as emerging molecules (for example a brominated flame retardant, HBCD), or PAHs. Our results point out the dominant impact of the molecule metabolism on the shape of its kinetics and on its rate of transfer to eggs.The developed dynamic mathematical model makes it possible to pilot variations with time of the size of the lipid compartments in the animal and of the frequency of laying. It was used to assess the influence of these animal characteristics on the transfer of POPs to eggs. Laying rate proportionally influences the contamination level of eggs and of animal tissues at steady state. Body fat dilutes absorbed POPs in absence of laying and significantly influences the rate of decontamination of tissues during depuration subsequent to an exposure period
Hleis, Dany. "Evaluation de la contribution d'émissions sidérurgiques à la teneur en particules en suspension dans l'atmosphère à une échelle locale". Littoral, 2010. http://www.theses.fr/2010DUNK0263.
Texto completoThe main objectives of this thesis were to explain the temporal variation of airborne particulate levels at a local scale in the city of Dunkirk (North of France) and to assess a source apportionment. A particular attention was paid to the impact of industrial emissions on air quality during the sampling period. Airbornes particulates were collected over four month period in 2008 under various influences : urban, industrial, sea and continental. Particulate emissions from an integrated steelworks were also analyzed to get their characteristics : element profiles from global analysis and data on individual particulate composition. In ambient air, the levels of metals and soluble ions contents depend not only on local emissions, but also on the contribution of long range transport particulate. Source apportionment was provided from the application of a weighted non negative matrix factorization (NMF) tool developed within the scope of this work. Results analysis did permit the evaluation of both industrial and non industrial contribution on the composition of airborne particulate
Borde, Xavier. "Association synergique de bactéries et d'une microalgue verte pour la biodégradation de polluants aromatiques modèles dans des cultures batch et continues". Rennes 1, 2001. http://www.theses.fr/2001REN10088.
Texto completoAmine, Chloe. "Millifluidique à gouttes : un outil pour le criblage des interactions entre biopolymères". Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4120.
Texto completoLiquid-liquid phase separation of aqueous biopolymers mixtures has been shown to strongly depend on various physico-chemical parameters. One sub-type of liquidliquid phase separation is known as complex coacervation and is primarily driven by attractive electrostatic interactions among two oppositely charged biopolymers. Understanding and characterizing specific conditions and factors leading to phase separated systems is an essential preliminary step in the further development of high values products that take advantage of such phenomenon. However, these screening studies, usually performed in bulk, are highly time consuming and require large quantities of raw materials not always available and sometimes expensive. The aim of this work was to develop a low material consuming droplets-based millifluidic device for the rapid screening of biopolymers interactions. The efficiency of the millifluidic device was demonstrated using a well-known case study of complex coacervation made of a protein-polysaccharide mixture, the ßlactoglobulin/ Gum Arabic mixture. This millifluidic device was then integrated in a multi-technics approach to study a second protein-polysaccharide mixture made of Napin and Pectin. The proposed millifluidic device is easy to implement and is therefore accessible to many laboratories. lt provides a low material consuming approach for rapid screening of biopolymers interactions, which is a prerequisite in the study of phase separation mechanisms
Lestienne, Isabelle. "Contribution à l'étude de la biodisponibilité du fer et du zinc dans le grain de mil et conditions d'amélioration dans les aliments de complément". Montpellier 2, 2004. http://www.theses.fr/2004MON20166.
Texto completoCamizuli, Estelle. "Impact des anciens sites miniers et métallurgiques sur les écosystèmes terrestre et aquatique actuels : étude comparative des deux moyennes montagnes : le Morvan et les Cévennes". Electronic Thesis or Diss., Dijon, 2013. http://www.theses.fr/2013DIJOL035.
Texto completoThe Morvan and the Cevennes Massifs are nowadays protected for their outstanding landscape and biodiversity. However since Prehistory, these regions experienced mining and smelting activities. Because of remnant properties, locating these ancient sites is capital and then impact on fauna and flora must be estimated. This present work is based in on a pluridisciplinary approach combining archeology, geochemistry, ecology and ecotoxicology. Statistical methods, from modern prospection technique, have been applied in order to delineate geochemical anomalies, potentially due to mining exploitation and thus facilitate the archeological prospection. Spatial distribution maps of trace metals were built on six sites (three in each park). Biodisponibility was assessed thanks to the analyses of wood mice, trout and bryophytes. Even if it seems that most of these elements belong to the non-extractible fraction of soil, the remaining bioavailable trace metals can be detected in the bioindicators. A negative relationship between Pb concentrations in animals and their body condition indices was found, and in some cases developmental instability was higher, suggesting deleterious effect on current wildlife. As a consequence, the impact of past mining and smelting works is still traceable in ecosystems. For this reason, these sites should be monitored, particularly in protected areas thought to be relatively free of anthropogenic contamination
Seyer, Marie-Ève. "Les fibres alimentaires et le pain de blé entier". Thesis, Université Laval, 2005. http://www.theses.ulaval.ca/2005/23027/23027.pdf.
Texto completoAlary, Rémi. "Isolement, caractérisation et importance technologique de deux gluténines de faible poids moléculaire chez le blé dur". Montpellier 2, 1988. http://www.theses.fr/1988MON20010.
Texto completoAdel, Kathryn. "Indice et charge glycémiques de l'alimentation et relations avec l'obésité et le syndrome métabolique au sein de l'étude des familles de Québec (QFS)". Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25199.
Texto completoMany high-carbohydrate foods common to Western diets have been shown to produce a high glycemic response, which may favor weight gain and metabolic syndrome (MetS), but associations between glycemic index (GI), glycemic load (GL) and obesity and MetS remain inconsistent. These associations were examined in the Quebec Family Study. GI and GL were positively associated with obesity, and an increase in GL over time was associated with gains in adiposity in women only. However, some associations were no longer significant when subjects with implausible reported energy intake (rEI) were excluded. GI and GL were generally not associated with MetS or its risk factors. Results suggest that GI and GL are associated with obesity in women, and that an increase in the GL of their diet is associated with gains in adiposity over time. They also reinforce the importance of considering implausible rEI in dietary surveys in relation to metabolic disease.
Guillard, Valérie. "Characterization and modelling of moisture transfer in composite foods constituted of fresh filling nd cereal-based food : barrier performance of edible films placed at the interface". Montpellier 2, 2003. http://www.theses.fr/2003MON20006.
Texto completoFournier, Agnès. "Transfert de Polluants Organiques Persistants (POP) vers l’œuf de poule : influence des caracteristiques des polluants et du statut physiologique de l’animal". Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL031N/document.
Texto completoLaying hens are likely to be exposed to a wide range of persistent organic pollutants (POPs) potentially present in their environment. In the context of securing poultry farming systems regarding POPs, our research has focused on identifying and grading factors likely to influence the transfer of ingested POPs to eggs. These factors are related to the nature of the ingested matrix (soil or feed), to the characteristics of the animal (laying rate, fatness) and to the properties of the molecule (lipophilicity, sensitivity to metabolism). Different scientific approaches have been implemented: in vivo experimentation and mathematical modeling. In the frame of in vivo experiments we have assessed the relative bioavailability of PCBs from one naturally contaminated soil. In addition, we have calculated parameters of the kinetics of transfer to eggs of molecules that had never been studied in laying hens, such as emerging molecules (for example a brominated flame retardant, HBCD), or PAHs. Our results point out the dominant impact of the molecule metabolism on the shape of its kinetics and on its rate of transfer to eggs.The developed dynamic mathematical model makes it possible to pilot variations with time of the size of the lipid compartments in the animal and of the frequency of laying. It was used to assess the influence of these animal characteristics on the transfer of POPs to eggs. Laying rate proportionally influences the contamination level of eggs and of animal tissues at steady state. Body fat dilutes absorbed POPs in absence of laying and significantly influences the rate of decontamination of tissues during depuration subsequent to an exposure period
Marot, Franck. "Caractérisation et traitement de sédiments de dragage contenant des polluants métalliques". Le Havre, 1997. http://www.theses.fr/1997LEHA0009.
Texto completoLacombe, Stéphanie. "Variabilité de la teneur et de la composition en isoflavones de la graine de soja (Glycine max. L. Merrill) et de ses dérivés alimentaires". Toulouse, INPT, 2000. http://www.theses.fr/2000INPT023A.
Texto completoLoeffler, Olivier. "Modélisation géoradar de la proche surface : estimation de la teneur en eau et influence d'un polluant". Strasbourg 1, 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/LOEFFLER_Olivier_2005.pdf.
Texto completoGround Penetrating Radar is used in near surface acquisitions to determine several characteristics from the soil. The analysis of the data is generally complicated by the heterogeneity of the near surface layer. The influence of water is also very strong and a change is the water content of the soil can change the results. In order to improve the data analysis, we use a modelling program with a finite differences in time domain (FDTD) algorithm. We determine the shape of the source impulse to be as near as possible from the real results. At first, we use this program to model the structure in a peat basin in the French Alps. We discover a geological structure which may result from a progressive sinking of the basin nearby the cliff. Another study helps us to discriminate between karsts filled with clay and hollow karsts in limestone. Finally, we can follow the changes affecting a snow layer at several times during the winter. We mounted a laboratory experiment in order to reproduce a groundwater level in a sand layer at varying depths. We had no signal reflection on the top of the saturated sand layer. We show that the 3 commonly used relations linking the water content to the relative dielectric permittivity give similar results, both on the water contents and on the variations of the water volume in the sand. With the modelling of the profiles from the sans box, we can give some estimations for the dielectric parameters of the sand. At last, we simulated an accidental fuel pollution from the surface of the sand box. We show that the fuel is not homogeneously distributed in the sand. We have no reflection on the fuel saturated layer, and only the wave velocity is clearly affected by the presence of fuel. The plume is more concentrated in the vicinity of the injection point and is the origin of water movements in the sand. New signals appear after a longer time due to these changes. A modelling gives a good idea from the shape of the plume
Richez, Elisabeth. "Germination et croissance de graminées sur des sols pollués par des hydrocarbures aromatiques polycycliques : implications en écotoxicologie et en phytomanagement". Littoral, 2000. http://www.theses.fr/2000DUNK0043.
Texto completoThe research concerns the interactions between vegetation and industrial soils contamined with polyaromatic hydrocarbons (PAH). The approach in situ is based on a phytosociological analysis of the present herbaceous plants on a fallow land of cokeworks combined with physio-chemical soil data. This study shows that there is no particular herbaceous vegetation related to the presence of the HAP in the soil. The experimental approach is based on the study of the development of two grasses, Lolium perenne and Alopecurus Myosuroides. On the polluted soil, a germination delay and a slower development of the roots of grasses are observed. However, no important effects of contaminants on the growth of the abroveground plant parts. The analysis of the contents of HAP in grasses, cultivated in a controlled environment with the atmosphere and the soil separated, shows that grasses are mainly contaminated through the roots. However, no phenomenon of bioaccumulation is observed. Furthermore, a translocation of a part of contaminants of the roots towards the abroveground plants parts is revealed. Long-term attempts show variations of behavior in the transfer of pollutants towards the air parts when plants are cultivated alone or together. In mixed culture, pollutants are almost not absorbed by Lolium perenne. On the contrary, Alopecurus myosuroides transfers in the stalks important quantities of HAP. Furthermore, these longer cultures, showed that the addition of a layer of healthy earth on the polluted soil limits strongly the contamination of vegetation. The question of the impact of vegetation on the decontamination of soils used during the experiments is analysed. The total concentrations of HAP are not significantly decreased after one year of Lolium perenne’s culture. Meanwhile, the concentrations of some contaminants like the benzo[g,h,i]perylene decrease, due to the simulation of microorganisms by the grasses
Bouvier, Nathalie. "Le soja : impact en nutrition et médecine humaine". Paris 5, 1998. http://www.theses.fr/1998PA05P145.
Texto completoTrichaiyaporn, Sommai. "Contribution à l'étude du séchage en discontinu de sucre cristallisé en lit fluidisé". Toulouse, INPT, 1991. http://www.theses.fr/1991INPT043G.
Texto completoReynaud, Patricia. "Analyses des résidus d'une triazole dans l'alimentation". Aix-Marseille 1, 1991. http://www.theses.fr/1991AIX11391.
Texto completoGraillot, Vanessa. "Appréciation quantitative de l'exposition alimentaire à des mélanges de pesticides et mécanismes de génotoxicité". Toulouse 3, 2012. http://thesesups.ups-tlse.fr/2077/.
Texto completoConsumers are exposed to several pesticide residues present simultaneously in food. This multi-exposure is insufficiently characterized and risk assessment procedures do not take into account appropriately the possible effects of contaminant mixtures. The purpose of this study was to investigate in vitro the genotoxic potential of pesticide mixtures relevant to the dietary exposure of the French population. In order to determine these mixtures, the French population co-exposure was estimated considering both food residue patterns originating from French food monitoring programs and French consumption survey (INCA2). Then, a statistic model was developed by ANSES to compare co-exposures, in order to define groups of individuals with similar pesticide exposure patterns. Based on these results, 7 relevant mixtures were determined and their genotoxic potential was screened in 4 different human cell lines (ACHN, HepG2, LS-174T, SHSY-5Y), using the genotoxic H2AX assay. Mixtures were tested at both equimolar concentrations and proportions reflecting the real diet contamination. The results were compared with the effects of individual compounds. One mixture, consisting of 5 compounds, was found to be genotoxic, only for HepG2. Data obtained with individual compounds showed that only two compounds from the mixture, namely fludioxonil and cyprodinil, were genotoxic. A mixture effect was observed at low doses. The screening of additional pesticides selected from the co-exposure characterization allowed to identify a family of pesticides (methyl-pyrazoles) able to induce DNA double strand break on two human cell lines (Jurkat/SH-SY5Y)
Vanin, Fernanda M. "Formation de la croûte du pain en cours de cuisson, propriétés rhéologiques et séchage en surface : une approche expérimentale de modélisation". AgroParisTech, 2009. http://www.theses.fr/2009AGPT0062.
Texto completoPakin, Caroline. "Le dosage de vitamines du groupe B (acide pantothénique et cobalamines) dans les aliments après isolement chromatographique et détection fluorimétrique". Université Louis Pasteur (Strasbourg) (1971-2008), 2004. https://publication-theses.unistra.fr/public/theses_doctorat/2004/PAKIN_Caroline_2004.pdf.
Texto completoThe developped method for the free pantothenic acid consists of a purification of the samples by successive passages through anion and cation exchange cartridges, then an isolation by reversed-phase chromatography followed by a post-column derivatization of pantothenic acid as a fluorescent isoindole (reaction of -alanin, formed by hot alkaline hydrolysis of pantothenic acid, with ortho-phthaldialdehyde in the presence of mercaptopropionic acid). An extraction procedure in two steps, first treatment by pepsin (hydrolysis of forms bound to proteins), then treatment by alkaline phosphatase and pantetheinase (hydrolysis of coenzyme A), allows to release the total vitamin B5 in the pantothenic acid form. As for free vitamin B12, the proposed protocol contains a very specific purification by passage through an immunoaffinity column, with concentration of the extract, then a transformation of the vitamin into ribazole (obtained by hot alkaline hydrolysis followed by a treatment by alkaline phosphatase). The fluorescent compound is then analysed by fluorimetry after a separation by reversed-phase chromatography. An enzymatic hydrolysis by pepsin allows to release the different forms of vitamin B12 bound to proteins and thus to obtain an estimation of the total vitamin B12 amount. These sensitive and repetable methods give good recovery rates. Owing to their low detection limit (0,65 µg. G-1 for the vitamin B5 and 1 ng. G-1 for the vitamine B12) and the good resolution of the peaks (respectively of pantothenic acid and of ribazole), they could most probably be applied to the determination of these vitamins in any foodstuff
Farah, Jinane. "Etude de la fraction lipidique de pollens allergisants et de ses modifications chimiques causées par les polluants atmosphériques". Thesis, Lille, 2018. http://www.theses.fr/2018LIL1R057.
Texto completoThe pollen lipidic fraction has an adjuvant effect on the allergic reaction and it is involved in germination processes. The alteration of pollen lipids by atmospheric pollutants is poorly documented in the literature although negative health effects are suspected. Our work was carried out on two highly allergenic pollens: timothy grass (phleum pratense) and birch tree (betula pendula). The lipid fraction of intact pollen was identified and quantified by gas chromatography equipped with a flame ionization detector or coupled to mass spectrometry. The main chemical families identified are: alkanes, alcohols, alkenes, saturated and unsaturated fatty acids, aldehydes and sterols. In vitro exposure of pollen to ozone has exhibited the reactivity of alkenes and the production of saturated fatty acids and aldehydes. Nitrogen dioxide has shown a protective role toward the reactivity of ozone. Furthermore, the bioavailability of lipids from intact pollen appears to be low as shown by pollen extractions with aqueous solvent without agitation. Moreover, our results give a new role to the rupture of pollen in the atmosphere. In fact, we observed a facilitated extraction of lipids for crushed pollen and in particular the release of immunostimulatory species such as linoleic and α-linolenic acids. The adjuvancy effects of the lipids extracted from broken or polluted pollen grains to the allergic reaction should be unraveled in a future work
Camizuli, Estelle. "Impact des anciens sites miniers et métallurgiques sur les écosystèmes terrestre et aquatique actuels : étude comparative des deux moyennes montagnes : le Morvan et les Cévennes". Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOL035/document.
Texto completoThe Morvan and the Cevennes Massifs are nowadays protected for their outstanding landscape and biodiversity. However since Prehistory, these regions experienced mining and smelting activities. Because of remnant properties, locating these ancient sites is capital and then impact on fauna and flora must be estimated. This present work is based in on a pluridisciplinary approach combining archeology, geochemistry, ecology and ecotoxicology. Statistical methods, from modern prospection technique, have been applied in order to delineate geochemical anomalies, potentially due to mining exploitation and thus facilitate the archeological prospection. Spatial distribution maps of trace metals were built on six sites (three in each park). Biodisponibility was assessed thanks to the analyses of wood mice, trout and bryophytes. Even if it seems that most of these elements belong to the non-extractible fraction of soil, the remaining bioavailable trace metals can be detected in the bioindicators. A negative relationship between Pb concentrations in animals and their body condition indices was found, and in some cases developmental instability was higher, suggesting deleterious effect on current wildlife. As a consequence, the impact of past mining and smelting works is still traceable in ecosystems. For this reason, these sites should be monitored, particularly in protected areas thought to be relatively free of anthropogenic contamination
Farah, Jinane. "Etude de la fraction lipidique de pollens allergisants et de ses modifications chimiques causées par les polluants atmosphériques". Electronic Thesis or Diss., Université de Lille (2018-2021), 2018. http://www.theses.fr/2018LILUR057.
Texto completoThe pollen lipidic fraction has an adjuvant effect on the allergic reaction and it is involved in germination processes. The alteration of pollen lipids by atmospheric pollutants is poorly documented in the literature although negative health effects are suspected. Our work was carried out on two highly allergenic pollens: timothy grass (phleum pratense) and birch tree (betula pendula). The lipid fraction of intact pollen was identified and quantified by gas chromatography equipped with a flame ionization detector or coupled to mass spectrometry. The main chemical families identified are: alkanes, alcohols, alkenes, saturated and unsaturated fatty acids, aldehydes and sterols. In vitro exposure of pollen to ozone has exhibited the reactivity of alkenes and the production of saturated fatty acids and aldehydes. Nitrogen dioxide has shown a protective role toward the reactivity of ozone. Furthermore, the bioavailability of lipids from intact pollen appears to be low as shown by pollen extractions with aqueous solvent without agitation. Moreover, our results give a new role to the rupture of pollen in the atmosphere. In fact, we observed a facilitated extraction of lipids for crushed pollen and in particular the release of immunostimulatory species such as linoleic and α-linolenic acids. The adjuvancy effects of the lipids extracted from broken or polluted pollen grains to the allergic reaction should be unraveled in a future work