• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 902
  • 582
  • 184
  • 96
  • 46
  • 42
  • 18
  • 18
  • 12
  • 11
  • 8
  • 8
  • 7
  • 7
  • 6
  • Tagged with
  • 2327
  • 775
  • 323
  • 322
  • 311
  • 235
  • 177
  • 148
  • 144
  • 140
  • 140
  • 135
  • 133
  • 123
  • 119
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
571

Evaluation de la contamination atmosphérique des écosystèmes en utilisant la composition isotopique du plomb et du mercure dans les lichens / Assessment of the atmospheric contamination of the ecosystems using the isotopic composition of lead and mercury in lichens

Barre, Julien 16 December 2013 (has links)
La signature isotopique du plomb (Pb) et du mercure (Hg) a été étudiée dans les lichens épiphytes des Pyrénées-Atlantiques. Un échantillonnage intégré et spatialisé à l’aide d’un système d’information géographique (SIG) a été mis en place afin de prendre en compte la diversité du territoire (occupation des sols, forêts, agriculture, industries et zones urbaines). A méso-échelle (département des Pyrénées-Atlantiques), la composition isotopique permet de différencier les zones impactées par les activités anthropiques mais aussi de discriminer l’origine de la contamination qu’elle soit de type industrielle ou urbaine. A l’échelle locale, la signature isotopique du Hg et Pb dans des lichens et des mousses prélevés dans la forêt d’Iraty (zone frontalière Franco-espagnole) a permis d’évaluer le type de dépôts accumulés dans ces différents bioaccumulateurs atmosphériques et le potentiel de ce nouvel outil pour le suivi des dépôts atmosphériques dans les écosystèmes éloignés. Enfin, sur la zone mercurifère d’Almadén (Castella la Mancha, Espagne) la signature isotopique du Hg dans les lichens et les sédiments apparait comme un outil pertinent pour étudier le transfert du Hg provenant de l’extraction minière vers les hydrosystèmes et l’atmosphère. / The isotopic signature of lead (Pb) and mercury (Hg) was measured in epiphytic lichens from Pyrénées-Atlantiques. An integrated and spatialized sampling was developed using geographical information system (GIS) to take into account the diversity of the territory (land-use, forest, agriculture, industries and urban areas). At meso-scale (county, Pyrenees-Atlantiques) the isotopic composition allows to differenciate areas impacted by anthropegenic activities and discriminate the origin of the contamination that it of industrial or urban type. At local scale, the isotopic signature of Hg and Pb in lichens and mosses sampled in Iraty forest (Franco-Spanish border) allowed to evaluate the kind of atmospheric deposits in these atmospheric bio-monitors and the potential of this new tool for the monitoring of atmospheric depositsin remote ecosystems. Finally, on the mercurifere area of Almadén (Castella la Mancha, Spain) the isotopic fingerprint of Hg in lichens and sediments appears to be a relevant tool to study the transfer of Hg from mining activities to hydrosystems and atmosphere.
572

Application of two dimensional compound specific carbon-chlorine isotope analyses for degradation monitoring and assessment of organic pollutants in contaminated soil and groundwater

Wiegert, Charline January 2013 (has links)
Nearly 250,000 sites with past and present potentially polluting activities need urgent remediation within Europe. Major pollutants include organochlorines (OCls), e.g. chlorinated ethenes (CEs) and hexachlorocyclohexanes (HCHs), mainly used as industrial solvents and pesticides, respectively. Due to improper handling and disposal, OCls contaminants are present in the soil or groundwater surrounding sites, where they have been produced or used. CEs and HCHs can undergo degradation by microorganisms indigenous to the soil or groundwater. Therefore natural attenuation (NA), relying on the in situ biodegradation of pollutants, is considered as a cost effective remediation strategy, yet it requires accurate monitoring methods. Compound specific isotope analysis (CSIA) is a powerful tool to provide information on the extent of degradation and, when combining two isotope systems (2D-CSIA), such as carbon (δ13C) and chlorine (δ37Cl), on reaction mechanisms. The diagnostic reaction-specific isotope enrichment factors (εC and εCl) were determined in laboratory experiments for the anaerobic degradation of PCE, TCE (Paper II) and α-HCH (Paper III) by mixed bacterial cultures enriched from CEs and HCHs contaminated sites, respectively. The related mechanism-specific εCl/εC ratios were calculated as 0.35 ± 0.11 (PCE), 0.37 ± 0.11 (TCE) and 0.52 ± 0.23 (α-HCH). These values are smaller than previously reported values for pure cultures. This is explained by the microbial community composition changes observed during degradation of PCE and α-HCH, which also reflect the variability of the microbial community at the field level. Furthermore, εCl/εC ratio might be bacteria specific. These values allowed the estimation of the extent of contaminant degradation at the respective study sites (Paper III and IV). Application of both isotope systems (δ13C and δ37Cl) led to comparable estimates. However the choice of representative ε values is crucial for an accurate assessment. These studies show that CSIA is useful to quantify in situ degradation of OCls contaminants and identify reaction pathways, by combining δ13C and δ37Cl. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.</p>
573

Facteurs de risque d´introduction et diagnostic de Mycobacterium avium ssp. paratuberculosis

Rangel Valderrama, Saray Julieth 04 1900 (has links)
Mycobacterium avium ssp. paratuberculosis (MAP) est l'agent causal de la paratuberculose, maladie entérique, chronique et incurable des ruminants, avec un impact économique important. Une meilleure compréhension des facteurs de risque associés à l'introduction de la maladie dans un troupeau est essentielle pour sa prévention. L’amélioration des tests diagnostiques est aussi importante pour son contrôle. L’introduction des nouveaux animaux dans le troupeau et la présence et contact des différentes espèces sauvages et domestiques avec les vaches, semblent être des facteurs de risques d’introduction de la maladie. Nous avons réalisé une revue systématique dont l`objective était de recueillir l’information pertinente pour répondre à la question sur l’importance de ces facteurs et leur impact sur l’introduction de la maladie dans un troupeau. D`un autre côté, la détection de MAP dans les fèces par culture bactérienne demeure la méthode diagnostique de choix malgré les facteurs qui l`affectent. Une série de 3 étapes est requise afin de confirmer la présence du MAP : (1) culture (2) coloration, et (3) confirmation du MAP par PCR (si détecté à l´étape 2). Certains échantillons fécaux présentent une particularité en raison de leur forte charge de micro-organismes. Ces contaminants peuvent interférer avec la croissance et la détection de MAP. Une étude visant à : a) estimer l'impact des certain covariables sur les résultats de la culture de MAP parmi l`analyse rétrospective d`un banque des données et b) évaluer la possibilité d'optimiser le processus de diagnostic du MAP en effectuant l'analyse PCR sur les cultures déclarées comme contaminées a été réalisée. / Mycobacterium avium ssp. paratuberculosis (MAP) is the causative agent of paratuberculosis an enteric, chronic and incurable disease of ruminants, with a major economic impact. A better understanding of the risk factors associated with the introduction of the disease in a herd, is essential for its prevention. Improving diagnostic tests are also important for the control. The introduction of new animals into the herd and the presence and contact of wild and domestic species with cattle, appear to be a risk factor for disease introduction. We conducted a systematic review to obtain relevant information to answer the question about the importance and impact of these factors on the introduction of the disease into a herd. On the other hand, the detection of MAP in feces by bacterial culture remains the diagnostic method of choice despite of the factors that can affect it. A series of 3 steps are required to confirm the presence of MAP: (1) culture (2) acid fast stain (3) MAP confirmation by PCR (if detected in step 2). Some fecal samples exhibit a particularity due to their normal heavy load of micro-organisms. These contaminants can interfere with the growth and detection of MAP. A study to: a) assess the impact of some covariables on the culture results by a retrospective analysis of a databank and b) to evaluate the possibility to optimize MAP diagnostic process by performing a PCR analysis on cultures declared as contaminated was realized.
574

Assessment of microbial loads of the Plankenburg and Berg Rivers and the survival of escherichia coli on raw vegetables under laboratory conditions

Barr, Alison, Ackermann, Alison 12 1900 (has links)
Thesis (MSc Food Sc (Food Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Over the last decade, studies on the quality of the water in many of South Africa.s rivers revealed an increase in pollution levels (DWAF, 1996; DWAF, 2000). In agricultural areas of the Western Cape many farmers draw water for irrigation from nearby rivers without knowing what the microbial pollution level is. In order to investigate the current quality of river water in some of the Western Cape.s major rivers and to explore the possibility of pathogen carryover from water onto produce, this research project was initiated. In an exploratory study over a five month period, the microbiological and water chemistry of three selected sites from the upper Berg and two from the Plankenbrug Rivers were assessed. Studied organisms included Salmonella, Staphylococcus, Listeria, endosporeformers, coliforms, Escherichia coli and intestinal Enterococci, while the chemical analysis consisted of pH, alkalinity, conductivity and chemical oxygen demand (COD). Faecal coliform counts ranging from 540 to 1 700 000 cfu.100ml-1 and 490 to 160 000 cfu.100ml-1 were found for the Berg and Plankenbrug Rivers, respectively. The water temperature ranged from 12º to 21ºC with COD values always below 100 mg.L-1. Potential human pathogens such as Salmonella, Staphylococcus, Listeria, endosporeformers, E. coli and intestinal Enterococci were frequently isolated from all five sites that were sampled. These results are of great concern to farmers, fresh produce retailers and consumers alike as the river water is regularly drawn for irrigation of produce that is later consumed raw or after a minimal processing step. From the exploratory study it was concluded that the water from all the sites were not suitable for use in irrigation practices as they regularly exceeded the guidelines for faecal coliforms and E.coli as set out by South African authorities. Irrigation with faecally polluted river water is one way that fruit and vegetables can become contaminated with foodborne pathogens. The risk of disease transmission from potential pathogens present in the irrigation water is influenced by the microbial load present and the numbers carried over to the produce. In this study the carry-over and survival of Escherichia coli on green beans, sugar-snap peas and cocktail tomatoes was assessed under controlled laboratory conditions. The produce was exposed to E.coli under different combinations of exposure times (5, 15 or 30 min), drying times (30 or 120 min) and different inoculum concentration ranges (107, 105, 104, 10³ and 10ª). In all cases a reduction of at least one log value in original inoculum number was found with the 10ª inoculums showing no survivors. Follow-up studies with an exposure time of 60 min and increased drying times of 6 or 12 h. Neither of these parameter changes affected the variation in numbers for the same inoculum or the E.coli survivors. Similar E.coli loads to those detected on the green beans were detected on the sugar-snap peas. The number of survivors on the cocktail tomatoes was much lower than found for the beans and peas. The number of survivors on the cocktail tomatoes was much lower than found for the beans and peas. This was attributed the 'smooth'surface of the tomato skin probably making attachment of the E.coli bacteria difficult. With the exception of the 10ª inoculum range, all E.coli survivors detected on the three types of produce studied exceeded the guideline numbers set for fresh produce. If similar survival patterns are to be found in the environment then results from this study should serve as a warning that the Plankenburg river water is unsafe for use in the irrigation of fresh produce. Some farmers are already treating river water with chlorine prior to irrigation to eliminate the chance of pathogen transfer onto produce. However, this is not a feasible solution for most farmers due to the high cost of implementing a system such as this. / AFRIKAANSE OPSOMMING: Oor die afgelope tien jaar het studies oor die gehalte van die water in baie van Suid-Afrika se riviere 'n toename in besoedelingsvlakke getoon. Baie boere in landbou gebiede van die Wes-Kaap wat watertrek vir besproeiing uit die nabygelee riviere is onbewus van die mikrobiese besoedelingsvlak van die rivier. Hierdie navorsingsprojek is geinisieer ten einde die huidige gehalte van die water in sommige van die Wes-Kaap se riviere te monitor, asook die moontlikheid van patogeen oordrag van die water na vars produkte te ondersoek. Met behulp van 'n verkennende studie oor . vyf maande tydperk, is die mikrobiologiese en water chemie kenmerke van drie geselekteerde moniteringspunte uit die boonste Bergrivier, en twee uit die Plankenburgrivier bemonster. Die bestudeerde organismes het ingesluit: Salmonella, Staphylococcus, Listeria, endosporeformers, fekale kolivorme, Escherichia coli en intestinale Enterococci. Die chemiese parameters het bestaan uit pH, alkaliniteit, geleiding, temperatuur en chemiese suurstof behoeftes (CSB). Fekale kolivorme tellings het gewissel van 540 - 1 700 000 cfu.100ml-1 en 490 tot 160 000 cfu.100ml-1 is gevind vir die Berg- en Plankenburgriviere, onderskeidelik. Die water temperatuur het gewissel van 12 º tot 21ºC met die CSB-waarde altyd onder 100 mg.L-1. Potensiele menslike patogene soos Salmonella, Staphylococcus, Listeria, endosporeformers, E. coli en intestinale Enterococci is dikwels geisoleer uit al vyf die moniteringspunte. Hierdie resultate is van groot belang vir boere, kleinhandelaars en varsprodukte verbruikers omdat die riviere se water gereeld onttrek word vir besproeiing van produkte wat later gebruik word in rou of in minimale geprosesseerde vorm. Vanuit die verkennende en uit die langer termyn studie (12 maande) is die gevolgtrekking gemaak dat die water vanuit die riviere nie geskik is vir gebruik in besproeiingspraktyke waar die riglyne vir fekale kolivorme en E. coli, soos uiteengesit deur die Suid-Afrikaanse owerhede, gereeld oorskry word nie. Besproeiing met fekale besoedelde rivierwater is een manier waarop groente en vrugte besmet kan word met voedsel patogene. Die risiko vir die oordrag van moontlike patogene teenwoordig in die besproeiingswater word beinvloed deur die mikrobiese lading teenwoordig en die getalle wat oorgedra word na die produkte. In hierdie studie is die oordrag en oorlewing van E. coli op groenboontjies, ertjies en tamaties onder beheerde laboratoriumtoestande beoordeel. Die produkte is blootgestel aan E. coli onder verskillende kombinasies van blootstellingstydperke (5, 15 of 30 min), drogingstye (30 of 120 min) en verskillende inokulum konsentrasies (107, 105, 104, 10³ en 10ª). In elke geval is . afname van ten minste een log waarde van die oorspronklike inokulum konsentrasie gevind. Die 10ª inokulum reeks het geen oorlewende selle getoon nie. Opvolg studies is gedoen met 'n blootstellingstyd van 60 min en verlengde drogingstye van 6 of 12 uur. Daar is gevind dat hierdie parameter veranderings die variasie in getalle vir dieselfde inokulum of die oorlewende E. coli nie beinvloed het nie. Soortgelyke E. coli ladings wat op die groenbone aangetref is, is ook op die ertjies aangetref. Die aantal oorlewendes op die tamaties was heelwat laer as die resultate vir die boontjies en ertjies. Dit word toegeskryf aan die "gladde" oppervlak van die tamatie-vel wat waarskynlik die aanhegting van die E. coli selle bemoeilik. Met die uitsondering van die 10ª inokulum reeks, het al die E. coli oorlewende selle gevind op die drie tipes produkte, die riglyn getalle oorskry wat vir vars produkte gestel is. As soortgelyke oorlewingspatrone gevind word in die omgewing, behoort die resultate van hierdie studie as waarskuwing te dien dat die water van die Plankenburgrivier ongeskik is vir die besproeiing van vars produkte. Sommige boere is reeds besig met chloor behandeling van die rivierwater voor besproeiing, om die kans van patogeenoordrag na die produkte uit te skakel. Dit is egter nie 'n haalbare oplossing vir die meeste boere nie as gevolg van die hoe kostes verbonde aan die implementering van' n stelsel soos hierdie.
575

Impact de l’environnement sur l’endommagement laser des optiques de silice du Laser MégaJoule / Impact of environmental contamination on laser induced damage of silica optics in Laser MegaJoule

Bien-Aimé, Karell Brigitte 23 November 2009 (has links)
Cette thèse vise à connaître et expliquer l’impact de la contamination moléculaire sur l’endommagement laser des optiques en silice d'un laser de puissance tel que le Laser Méga Joule (LMJ). L'une des causes de l'endommagement prématuré de ces optiques est l'adsorption de polluants moléculaires ou particulaires à leur surface. Dans le contexte particulier du LMJ, nos conditions d'études laser sont des fluences supérieures à 10 J/cm², une longueur d’onde de 351 nm et une durée d’impulsion de 3 ns pour une irradiation en monocoup. Des prélèvements moléculaires, l’analyse du dégazage des matériaux, et l’identification de la contamination condensée sur les surfaces des optiques présentes dans des environnements jugés critiques, ont permis de déterminer certains polluants critiques. Des expériences de contamination contrôlée impliquant ces polluants ont alors été menées afin de comprendre et modéliser leur effet sur l'endommagement laser des optiques. Ceci nous a conduits à proposer plusieurs mécanismes supposés. / Laser induced damage impact of molecular contamination on fused polished silica samples in a context of high power laser fusion facility, such as Laser MegaJoule (LMJ) has been studied. One of the possible causes of laser induced degradation of optical component is the adsorption of molecular or particular contamination on optical surfaces. In the peculiar case of LMJ, laser irradiation conditions are a fluence of 10 J/cm², a wavelength of 351 nm, a pulse duration of 3 ns for a single shot/days frequency. Critical compounds have been identified thanks to environmental measurements, analysis of material outgassing, and identification of surface contamination in the critical environments. Experiments of controlled contamination involving these compounds have been conducted in order to understand and model mechanisms of laser damage. Various hypotheses are proposed to explain the damage mechanism.
576

Etude du dégazage des résines pour les lithographies électronique et extrême ultraviolet / Resists outgassing study for the e-beam and euv lithographies

Mebiene-Engohang, Armel-Petit 09 January 2015 (has links)
La lithographie électronique multifaisceaux (ou multi e-beam) en cours de développement est pressentie comme une alternative à la photolithographie 193 nm à immersion (193i nm) pour la production des circuits intégrés des noeuds technologiques avancés (14 nm et au-delà). Elle se présente également comme un concurrent potentiel à la photolithographie sous rayonnement EUV (13,5 nm) qui, elle aussi, est en cours de développement. Cependant, le développement de cette technologie doit faire face à plusieurs obstacles. Parmi eux, on a la contamination des optiques électroniques induite par le redépôt des molécules dégazées de la résine au cours de l‟exposition. Ces dépôts conduisent à la croissance d‟une couche carbonée en surface et à l‟intérieur des trous de ces optiques. Cette couche de contamination a tendance à diminuer la transmission des optiques et, par conséquent, diminuer les performances lithographiques de l‟outil (débit, uniformité des CD, rugosité, etc.). Il est donc indispensable de comprendre les mécanismes qui gouvernent le dégazage et la croissance de la couche de contamination afin d‟être en mesure de prédire son rôle sur les dérives des procédés et de l‟équipement. Tel a été l‟axe conducteur de ces travaux de thèse. Dans un premier temps, nous avons réalisé l‟état de l‟art des travaux déjà effectués dans le cas de la technique de lithographie EUV. Ensuite, nous avons conçu et fabriqué un banc de tests et développé, en parallèle, les méthodologies permettant de réaliser les études de dégazage des résines et de contamination induite sur des dispositifs simulateurs d‟optiques électroniques, appelés « mimics ». Puis, dans les conditions opératoires similaires à la plateforme Matrix développée par MAPPER Lithography, nous avons évalué le dégazage des résines de différentes formulations et mesuré la contamination induite par chacune de ces formulations sur les mimics à l‟aide du banc de tests développé. Enfin, nous avons proposé un modèle analytique permettant de prédire la croissance du film de contamination à l‟intérieur des trous du mimic en fonction des paramètres d‟exposition. / The development of multiple e-beam lithography equipment is foreseen as an alternative to the 193i nm immersion photolithography for the advanced technological node (less than 14 nm). This next generation lithography is a potential challenger to the EUV (13.5 nm) lithography which is also under development. However, this technology faces important challenges in controlling the contamination of the electron optics due to the adsorption of molecules outgassed from resist under exposure and the subsequent formation of a carbonaceous film on optics surface. This contamination layer can lead to the transmission loss of the optics and, consequently, degrade the tool lithographic performances (throughput, CD uniformity, Line Width Roughness, etc.). It is thus important to understand the resist outgassing and induced contamination mechanisms in order to predict their effect on the process drifts. That was the driver axis of these thesis works. Firstly, we performed the state of the art related to the works already published in the EUV lithography case. Secondly, we designed and built-up an experimental setup and developed, in parallel, the methods allowing to study the mechanisms of resist outgassing and induced contamination on electron optics simulators, called “mimic”. Thirdly, we assessed the outgassing of several resist formulations in the same operating conditions as in the Matrix platform developed by MAPPER Lithography. We also measured the induced contamination layer on the mimics for each resist formulation using the developed experimental setup. And finally, we proposed an analytical model that allows to predict the contamination film growth inside mimic holes during exposure.
577

Avaliação do impacto ambiental e caracterização geoquímica de contaminantes em solo e água subterrânea na área do aterro de resíduos industriais da UTRESA na região do Vale dos Sinos, em Estância Velha, RS

Augustin Junior, Pedro Valter January 2011 (has links)
A contaminação de resíduos industriais é um grande problema ambiental relacionado ao desenvolvimento industrial e urbano atual. A região do Vale dos Sinos, RS tem um histórico preocupante no gerenciamento e na destinação final de resíduos industriais ali gerados. Este estudo foi realizado na Central de resíduos da UTRESA, no município de Estância Velha, e teve como objetivo o diagnóstico ambiental e a caracterização do comportamento geoquímico de contaminantes em solo e águas subterrâneas. A metodologia do estudo consistiu no mapeamento e caracterização geológica e hidrogeológica, instalação de poços de monitoramento e sondagens, amostragens de chorume, solo e águas subterrâneas e superficiais, análises físico-químicas de chorume, água e solo, ensaios de lixiviação e difratometria de raios-X em solo, ensaios de slug, diagnóstico ambiental, avaliação de risco e proposta de remediação da área de estudo. Foram instalados 25 poços de monitoramento, coletadas e analisadas 73 amostras (chorume, solo e águas). Os resultados obtidos mostram ampla contaminação do solo e da água subterrânea na área de influência do aterro de resíduos industriais da UTRESA, com intensidade variada nos diferentes contaminantes. Cromo, cloreto e nitrogênio amoniacal apresentam os níveis mais elevados de contaminação, o que reflete o maior conteúdo registrado nas amostras de chorume analisadas. Hidrocarbonetos de petróleo, cianetos e mercúrio exibem contaminações de baixa intensidade com ampla distribuição. Chumbo, cobre e bário, por outro lado, registram contaminação fraca e restrita a poucos locais. A contaminação do solo é registrada principalmente na zona subsaturada do aquífero, nos locais de convergência das águas pluviais situadas a nordeste e sul das células de deposição de resíduos, o que reflete a disseminação preferencial dos contaminantes pelo fluxo superficial seguido de infiltração no solo. Este processo de transporte de contaminação implica, também, em alto risco de contaminação das águas superficiais dos corpos receptores adjacentes. Os resultados dos ensaios de lixiviação indicam fraco potencial de contaminação das águas subterrâneas. A degradação ambiental registrada no local decorre das condições inadequadas de disposição e confinamento dos resíduos em células construídas a margem das normas técnicas, não atendendo as especificações de impermeabilização de base e topo e no dimensionamento dos taludes. / Contamination of industrial wastes represent a great environmental problem related to industrial and urban development. Historically the Vale dos Sinos region has adopted inadequate procedures in the management and final disposal of its industrial waste. This study was realized in the UTRESA landfill area to do an environmental diagnostic and to characterize the geochemical behavior of contaminants in soils and groundwater.The study was performed by geological and hydrogeological mapping, installation of monitoring wells and borings, sampling of landfill leachate, soil, groundwater and surface water, physical-chemical analysis of landfill leachate, water and soil, leaching tests and X-ray diffraction on the soil, slug tests, environmental diagnostic, risk evaluation and proposed remediation for the studied area. Twenty five monitoring wells were installed and were collected and analyzed 73 samples (landfill leachate, soil and waters). The results show widespread contamination of soil and groundwater in the influence area of UTRESA industrial waste landfill, with varying intensity in different contaminants. Chromium, chloride and ammonium have higher levels of contamination, which reflects the highest content recorded in the manure samples analyzed. Petroleum hydrocarbons, cyanide and mercury contamination exhibit low intensity with a wide distribution. Lead, copper and barium, on the other hand, show low contamination restricted to a few locations. Soil contamination is recorded mainly in the vadose zone of the aquifer, at the convergence locals of stormwater situated to the northwest and south of the waste disposal cells, showing the preferential spread of contaminants by surface flow followed by soil infiltration. This transport process of contaminants also results in high risk of contamination of adjacent streams. The results of leaching tests indicate low potential for groundwater contamination by dessortion of metals from the soil. Environmental degradation registered on the site results from the inadequate conditions of disposal and confinement of waste in the cells constructed without complying the technical standards.
578

Avaliação do impacto ambiental e caracterização geoquímica de contaminantes em solo e água subterrânea na área do aterro de resíduos industriais da UTRESA na região do Vale dos Sinos, em Estância Velha, RS

Augustin Junior, Pedro Valter January 2011 (has links)
A contaminação de resíduos industriais é um grande problema ambiental relacionado ao desenvolvimento industrial e urbano atual. A região do Vale dos Sinos, RS tem um histórico preocupante no gerenciamento e na destinação final de resíduos industriais ali gerados. Este estudo foi realizado na Central de resíduos da UTRESA, no município de Estância Velha, e teve como objetivo o diagnóstico ambiental e a caracterização do comportamento geoquímico de contaminantes em solo e águas subterrâneas. A metodologia do estudo consistiu no mapeamento e caracterização geológica e hidrogeológica, instalação de poços de monitoramento e sondagens, amostragens de chorume, solo e águas subterrâneas e superficiais, análises físico-químicas de chorume, água e solo, ensaios de lixiviação e difratometria de raios-X em solo, ensaios de slug, diagnóstico ambiental, avaliação de risco e proposta de remediação da área de estudo. Foram instalados 25 poços de monitoramento, coletadas e analisadas 73 amostras (chorume, solo e águas). Os resultados obtidos mostram ampla contaminação do solo e da água subterrânea na área de influência do aterro de resíduos industriais da UTRESA, com intensidade variada nos diferentes contaminantes. Cromo, cloreto e nitrogênio amoniacal apresentam os níveis mais elevados de contaminação, o que reflete o maior conteúdo registrado nas amostras de chorume analisadas. Hidrocarbonetos de petróleo, cianetos e mercúrio exibem contaminações de baixa intensidade com ampla distribuição. Chumbo, cobre e bário, por outro lado, registram contaminação fraca e restrita a poucos locais. A contaminação do solo é registrada principalmente na zona subsaturada do aquífero, nos locais de convergência das águas pluviais situadas a nordeste e sul das células de deposição de resíduos, o que reflete a disseminação preferencial dos contaminantes pelo fluxo superficial seguido de infiltração no solo. Este processo de transporte de contaminação implica, também, em alto risco de contaminação das águas superficiais dos corpos receptores adjacentes. Os resultados dos ensaios de lixiviação indicam fraco potencial de contaminação das águas subterrâneas. A degradação ambiental registrada no local decorre das condições inadequadas de disposição e confinamento dos resíduos em células construídas a margem das normas técnicas, não atendendo as especificações de impermeabilização de base e topo e no dimensionamento dos taludes. / Contamination of industrial wastes represent a great environmental problem related to industrial and urban development. Historically the Vale dos Sinos region has adopted inadequate procedures in the management and final disposal of its industrial waste. This study was realized in the UTRESA landfill area to do an environmental diagnostic and to characterize the geochemical behavior of contaminants in soils and groundwater.The study was performed by geological and hydrogeological mapping, installation of monitoring wells and borings, sampling of landfill leachate, soil, groundwater and surface water, physical-chemical analysis of landfill leachate, water and soil, leaching tests and X-ray diffraction on the soil, slug tests, environmental diagnostic, risk evaluation and proposed remediation for the studied area. Twenty five monitoring wells were installed and were collected and analyzed 73 samples (landfill leachate, soil and waters). The results show widespread contamination of soil and groundwater in the influence area of UTRESA industrial waste landfill, with varying intensity in different contaminants. Chromium, chloride and ammonium have higher levels of contamination, which reflects the highest content recorded in the manure samples analyzed. Petroleum hydrocarbons, cyanide and mercury contamination exhibit low intensity with a wide distribution. Lead, copper and barium, on the other hand, show low contamination restricted to a few locations. Soil contamination is recorded mainly in the vadose zone of the aquifer, at the convergence locals of stormwater situated to the northwest and south of the waste disposal cells, showing the preferential spread of contaminants by surface flow followed by soil infiltration. This transport process of contaminants also results in high risk of contamination of adjacent streams. The results of leaching tests indicate low potential for groundwater contamination by dessortion of metals from the soil. Environmental degradation registered on the site results from the inadequate conditions of disposal and confinement of waste in the cells constructed without complying the technical standards.
579

La notion de mineur dans l'oeuvre de Pier Paolo Pasolini / The notion of minor in Pier Paolo Pasolini's works

Passerone, Léa 09 December 2017 (has links)
Cette thèse se propose d’étudier la façon dont l’idée de mineur traverse l’œuvre de Pier Paolo Pasolini, que ce soit dans son sens linguistique et littéraire (rapport aux langues et aux auteurs dits « mineurs »), sociopolitique (présence des subalternes et des minorités), ou encore spirituel (« mineur » au sens franciscain). L’ensemble de la vaste production artistique et critique de l’auteur italien que nous prenons en considération semble en effet guidé par le désir de porter à la lumière et de valoriser ce qui d’ordinaire est dénigré, oublié et situé au bas des hiérarchies, quelles qu’elles soient : paysans frioulans, sous-prolétaires romains, peuples du Tiers Monde, langues et cultures périphériques, etc. Les notions de « minore » (« mineur ») et de « minoranza » (« minorité ») paraissent d’autant plus significatives et pertinentes qu’elles sont utilisées et problématisées par l’écrivain-cinéaste, de ses premiers essais littéraires à ses derniers articles et scénarios, à des moments clés de son parcours. Elles se révèlent en outre étroitement liées aux périodes de profondes transformations socio-culturelles que traverse l’Italie, dont elles se font le reflet antithétique. Alors que le prétendu « miracle économique » bat son plein au cœur des années 1960, la notion de mineur, centrée autour de l’idée d’infériorité et d’humilité, cède la place à la notion plus politique et polémique de minorité. Si cette dernière reprend certains traits de la précédente, elle se définit davantage comme altérité radicale et puissance de contestation des modèles dominants, tout en accentuant l’esthétique et la poétique de la contamination, selon lesquelles humilis et sublimis sont indissociables. / This PhD thesis intends to explore how the idea of minor is present throughout Pier Paolo Pasolini’s works, in its linguistic and literary sense (linked to languages and authors called « minors »), in its socio-political sense (presence of the subalterns and the minorities), or even in its spiritual sense (« minor » according to Franciscans). The extensive artistic and critical production of the Italian author who we consider, seems in fact to be guided by the will of highlighting and promoting what is usually depreciated, forgotten and situated at lower levels in every hierarchy : Friulian peasants, Roman sub-proletarians, people from the Third World, outlying languages and cultures, etc. The notions of minor and minorities are particularly significant and relevant, given that they are used and questionned by the writer and the director from his first literary essays to his last articles and scenarios, in key moments of his career. Furthermore, they appear closely associated to the period of deep socio-cultural changes that Italy is experiencing, hence the contradicting images they convey. While the so-called « economic miracle » is triumphal in the sixties, the notion of « minor », centered on the idea of inferiority and humility, is replaced by the more political and polemical notion of minority. If this last notion has some characteristics of the former one, it should also be defined as a radical alterity and contesting power of the dominant models, at the same time keeping the emphasis on the contamination esthetic and poetics, whereby humilis and sublimis are inseparable.
580

Caractérisation et simulation de la contamination et de la décontamination moléculaire des containers plastiques (FOUPs) de l'industrie microélectronique / Characterization and simulation of the molecular contamination and decontamination of plastic containers (FOUPs) in microelectronics industry

Nguyen, Thi Quynh 20 December 2012 (has links)
Dans l'industrie des semi-conducteurs, les plaques de silicium sont stockées dans des containers, appelés FOUPs (Front Opening Unified Pod) conçus à base de matériaux polymères (PC, PEEK, COP, PEI). De tels matériaux sont capables de sorber des contaminants moléculaires volatils et de les relarguer ultérieurement en présence de plaques, entraînant de la défectivité. Cette thèse a pour but d'apporter une meilleure connaissance et compréhension de la contamination et décontamination moléculaire des FOUPs au travers de quatre axes d'étude : - La détermination de la nature, des sources et des niveaux des contaminants moléculaires des FOUPs. Les acides HF et HCl, ont été détectés au ppbv – ppmv, et apparaissent comme les contaminants critiques. - L'étude des mécanismes de sorption et dégazage de HF et HCl gazeux dans les polymères. Ils ont été caractérisés par l'établissement, pour la première fois, des coefficients de solubilité (~10-1 m3(STP).m-3. Pa-1) et de diffusion (~ 10-15 m2/s) dans les conditions industrielles (22°C, 40% RH, 1 atm). - L'évaluation expérimentale de l'efficacité du nettoyage des FOUPs par différentes méthodes de décontamination (AUD, DMS, APR) à partir de FOUPs volontairement contaminés en HF. La mise sous vide à 70°C permet de décontaminer partiellement le FOUP du contaminant piégé dans le volume du polymère tandis que le nettoyage humide ou la mise sous vide à froid ne peuvent enlever que la contamination de proche surface du FOUP. - L'établissement d'un modèle de contamination des polymères du FOUP, basé sur les lois de Fick et de Henry et utilisant les coefficients de solubilité et diffusion établis. Ce modèle a été proposé et implémenté sur Comsol Multiphysics. Pour la première fois, le comportement dynamique du contaminant dans l'atmosphère et dans les matériaux du FOUP au cours de différents événements de contamination et de décontamination du FOUP a été déterminé par simulation numérique. Ainsi, les profondeurs de diffusion de la contamination dans les polymères ont été évaluées (de quelques dizaine à centaines de µm 48 h après un événement de contamination) ou encore l'efficacité de décontamination de méthodes de nettoyage a pu être estimée. / In the microelectronics industry, the silicon substrates (wafers) are stored in containers, named FOUP (Front Opening Unified Pod) made in polymers (PC, PEEK, COP, PEI). Such materials are able to sorb the volatile molecular contaminants and subsequently outgas these ones in presence of wafers, leading then to defectivity. This thesis aims to provide a better knowledge and comprehension of FOUP molecular contamination and cleaning, in focusing on four areas: - The determination of the nature, sources and levels of FOUP molecular contaminants. The HF and HCl acids, have been detected in ppbv – ppmv range, and appear as some critical contaminants. - The study of the sorption and outgassing mechanisms of HF and HCl gaseous in polymers. They have been characterized by the establishment, for the first time, of the solubility (~10-1 m3(STP).m-3. Pa-1) and diffusion coefficients (~ 10-15 m2/s) in industrial conditions (22°C, 40% RH, 1 atm). - The cleaning efficiency of different FOUP decontamination methods (AUD, APR, DMS) has been experimentally evaluated from intentionally contaminated FOUPs with HF. The vacuum at 70°C enables to partially decontaminate the contaminants trapped in polymer volume whereas the wet cleaning or the vacuum at ambient temperature can remove only contaminants on the near-surface of the FOUP materials. - The implementation of a model of FOUP polymer contamination, based on Fick and Henry laws and using the established solubility and diffusion coefficients. This model has been proposed and implemented on Comsol Multiphysics. For the first time, the dynamic behaviour of contaminant in the atmosphere and in the FOUP's materials during different contamination and decontamination events has been determined by numerical simulation. Thus the diffusion depth of the contaminant in polymeric materials has been evaluated (few tens to hundreds of µm 48 h after one contamination event) and also the decontamination efficiency of cleaning methods has been able to be predicted.

Page generated in 0.3841 seconds