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Gregušová, Michaela. "Modifikace techniky difúzních gelů (DGT) pro charakterizaci přírodních systémů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-233319.
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Diffusive gradient in thin film technique (DGT) represents a relatively new approach for in situ determinations of labile metal-species in aquatic systems. The DGT device passively accumulates labile species from the solution while deployed in situ, and therefore contamination problems associated with conventional collection and filtration procedures are eliminated. This study deals with a possible modification of DGT technique. The key of using DGT technique for speciation analysis of metals is to find out suitable binding phase and diffusion layer. The new resin gel based on Spheron Oxin (5 sulphophenyl-azo-8-hydroxyquinoline) ion exchanger with a higher selectivity to trace metals than Chelex 100 could potentially provide more information on metals speciation in aquatic systems. The performance of this new binding phase was tested for the determination of Cd, Cu, Ni, Pb and U under laboratory conditions. The hydrogel layer based on poly(2-hydroxyethyl methacrylate) was synthesized and tested as a new diffusion gel for application in DGT technique.
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Devillers, Delphine. "Fiabilisation de la quantification des éléments traces cationiques et anioniques par la technique d'échantillonnage DGT en milieu aquatique naturel." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0058/document.
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La technique d’échantillonnage passif DGT (« Diffusive Gradients in Thin Films ») possède de nombreux avantages (intégration des variations temporelles, abaissement des limites de quantification) qui font d’elle une méthode prometteuse pour une utilisation en réseaux de mesure pour quantifier les éléments traces dans les eaux naturelles. Cependant, il existe encore des zones d’ombre qui constituent des freins à son utilisation dans un contexte réglementaire. Ce travail a donc pour objectif d’identifier des biais potentiels et ainsi contribuer à fiabiliser la méthode. Cette étude montre que l’obtention d’un résultat avec une incertitude minimisée doit passer par la détermination expérimentale des facteurs d’élution ; cependant, l’utilisation d’une valeur standard de 0,8 pour le Cr(III) et de 0,85 pour Al(III), Cd(II), Co(II), Cu(II), Ni(II), Pb(II) et Zn(II) est proposée afin d’alléger les manipulations tout en conservant une incertitude raisonnable (<10%). L’étude de l’influence de l’encrassement des dispositifs DGT a montré que la sorption des cations Cd(II), Cu(II) et Pb(II) sur les filtres encrassés affectent respectivement peu, modérément et fortement leur accumulation dans les échantillonneurs et donc leur quantification. Des durées d’exposition de moins d’une semaine sont alors préconisées pour ces éléments. En revanche, l’encrassement a eu un impact négligeable sur le Ni(II) et sur les oxyanions As(V), Cr(VI), Sb(V) et Se(VI). Enfin, une méthode de quantification simultanée du Cr(III), essentiel à la vie, et du Cr(VI), toxique, a été développée en vue d’améliorer l’évaluation de la toxicité d’une eau. Un unique échantillonneur DGT fixe les deux formes tandis qu’elles sont ensuite sélectivement séparées par une étape d’élution. Cette méthode est robuste sur une large gamme de forces ioniques et de concentrations en sulfate mais sur une gamme de pH plus restreinte ne couvrant pas toutes les eaux naturelles (4 à 6)The passive sampling DGT technique (Diffusive Gradients in Thin Films) has a lot of benefits (time-weighted average concentrations, low limits of quantification) and would therefore be a useful tool for monitoring studies to quantify trace elements in natural water. However, there are still some limitations and grey areas that put the brakes on the development of the method for regulatory applications. The aim of this work is to identify potential biases and contribute to increase the method reliability. This study shows that a minimized uncertainty on results can be obtained only if elution factors are experimentally determined; however, standard values of 0.8 for Cr(III) and 0.85 for Al(III), Cd(II), Co(II), Cu(II), Ni(II), Pb(II) and Zn(II) are suggested to reduce manipulations while keeping reasonable uncertainty (<10%). Studying the influence of fouling developed on DGT devices showed that the sorption of cations Cd(II), Cu(II) and Pb(II) had, respectively, a slight, moderate and strong impact on their accumulation in DGT samplers and therefore on their quantification. Samplers should then be deployed for less than one week. In contrast, fouling had a negligible impact on oxyanions As(V), Cr(VI), Sb(V) and Se(VI). Finally, a method was developed to simultaneously quantify both Cr oxidation states naturally occurring in natural waters, which are Cr(III), essential to life, and Cr(VI), toxic. Both forms are accumulated in a single DGT sampler before being selectively separated during an elution step. This method is robust for wide ranges of ionic strengths and sulfate concentrations but for a narrower range of pH (4 to 6)
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Kane, David. "Evaluating phosphorus availability in soils receiving organic amendment application using the Diffusive Gradients in Thin-films (DGT) technique." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8001.
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Phosphorus is a resource in finite supply. Use of organic amendments in agriculture can be a sustainable alternative to inorganic P, provided it can meet crop requirements. However a lack of consistent knowledge of plant P availability following application of organic amendments, limits its potential. Studies suggest chemical extraction procedures, may not reflect plant available P. The Diffusive Gradients in Thin-films (DGT) technique is based on natural diffusion of P via a hydrogel and sorption to a ferrihydrite binding layer; which should accurately represent soil P (CDGT) in a plant available form. The aim of this research was to evaluate changes in soil P availability, following the addition of organic amendments, cattle farmyard manure (FYM), green waste compost (GW), cattle slurry (SLRY) and superphosphate (SP) using Olsen P and DGT. The research included incubation, and glasshouse studies, using ryegrass (Lolium perenne L.). Soils with a history of application of the aforementioned organic amendments were used (Gleadthorpe), as well as a soil deficient in P (Kincraigie). The hypotheses were as follows H1 A build-up of P available by diffusive supply, from historic treatment additions and subsequent availability from fresh treatment additions will be demonstrated by DGT. H2 Historical treatment additions are more important at determining yield and P uptake than fresh additions. H3 DGT can detect changes in P available by diffusive supply following addition of different treatments and subsequently following lysis of microbial cells on a soil deficient in P. H4 DGT will provide a more accurate indication of plant P availability than organic amendments in a soil deficient in P. H5 P measurements using DGT will be lower from organic amendments than superphosphate.H6 DIFS simulations of soil kinetic parameters will provide additional information about how treatments influence P resupply from solid phase to solution following DGT deployment. Cont/d.
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Österlund, Helene. "Applications of the DGT technique for measurements of anions and cations in natural waters." Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16785.
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Since the toxicity and mobility of trace metals are related to the metals' speciation, robust methods for trace metal speciation analysis are of great interest. During the last 15 years, hundreds of scientific articles have been published on the development and applications of the diffusive gradients in thin films (DGT) passive sampling technique.In this work the commercially available DGT containing ferrihydrite adsorbent, used for determination of phosphate and inorganic arsenic, was characterised with respect to anionic molybdate, antimonate, vanadate and tungstate determination. Tests were performed in the laboratory as well as in the field. Diffusion coefficients were determined for the anions using two different methods with good agreement. Simultaneous measurements of arsenate were conducted as quality control to facilitate comparison of the performance with previous work. The ferrihydrite-backed DGT was concluded useful for application over the pH-range 4 to 10 for vanadate and tungstate, and 4 to <8 for molybdate and antimonate. At pH values ≥8, deteriorating adsorption was observed.The combination of a restricted pore (RP) version of DGT and the normal open pore (OP) DGT was used for speciation of copper and nickel at three brackish water stations with different salinities in the Baltic Sea. Time series and depth profiles were taken, and complementary membrane- (<0.22 μm) and ultrafiltration (<1 kDa) was conducted. Comparing DGT and ultrafiltration measurements indicated that copper and nickel were complexed. Due to small differences in results between the OP and RP DGTs it was suggested that the complexes were smaller than the pore size of the RP gel (~1 nm) resulting in that both DGTs accumulating essentially the same fraction. Further, there seemed to be a trend in copper speciation indicating higher degree of strong complexation with increasing salinity. The low salinity stations are more affected by fluvial inputs which will likely affect the nature and composition of the organic ligands present. Assuming that copper forms more stable complexes with ligands of marine rather than terrestrial origin would be sufficient to explain the observed trend.Godkänd; 2010; 20100517 (helost); LICENTIATSEMINARIUM Ämnesområde: Tillämpad geologi/Applied Geology Examinator: Professor Johan Ingri, Luleå tekniska universitet Diskutant: Docent Per Andersson, Naturhistoriska Riksmuseet Tid: Fredag den 18 juni 2010 kl 10.00 Plats: F341, Luleå tekniska universitet
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Bořek, Tomáš. "Toxické kovy ve vodě a sedimentech vodní nádrže Brno." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216543.
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Diploma thesis deals with usage of the diffusive gradients in thin films technique (DGT) for the determination of labile metal species in the surface water and sediments of Brno water reservoir. Sediment and water samples were collected on the selected sides of Brno water reservoir on September and October 2008. The DGT technique was used for determination of depth profiles of Fe, Mn, Pb, Cd, Zn, Cu, Ni and Al. The DGT probes with three different thicknesses of diffusive layer were applied into the sediment samples. The obtained results gave the information about release of metals from solid phase into the pore water of sediment. The concentrations of Fe, Mn, Pb and Cd in sediments were determined by atomic absorption spectrometry after microwave decomposition. The DGT technique was used also for determination of Fe, Mn, Pb and Cd in surface water from Brno water reservoir.
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Finsterlová, Hana. "Studium vlastností sorpčních gelů pro stanovení rtuti technikou DGT." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216541.
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The aim of this thesis is testing of resin gels used in diffusive gradients in thin films technique (DGT) for determination of mercury in natural waters. The sorbets, chosen for preparation of resing gels were: Duolit GT- 73, Spheron- Thiol, and Chelex 100 and newly modified sorbent Iontosorb AV. At the beginning of work, the preparation procedure of all resing gels was optimized. After optimalization of preparation procedure the resin gels were tested in mercury model solutions. The recovery test and time dependence test were performed. When the basic tests were finished, they were followed by the tests of influence of natural ligand (humic acids and chlorides), and other parameters (above all pH and ionic strenght), on mercury determination by DGT technique.
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Cole, Russell Francis. "Determination of organotin compounds in coastal sediment pore-water by diffusive gradients in thin-films (DGT) technique." Thesis, University of Portsmouth, 2016. https://researchportal.port.ac.uk/portal/en/theses/determination-of-organotin-compounds-in-coastal-sediment-porewater-by-diffusive-gradients-in-thinfilms-dgt-technique(f452f268-d8c7-4ca9-acb3-ffd6fb733f8e).html.
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Organotin compounds still present a high risk to biota in the aquatic environment. Measuring the behaviour of the freely dissolved fractions of these compounds in sediment compartments is challenging, with costly and sensitive analytical techniques required for their measurement. Diffusive gradients in thin-films (DGT) allow for the uptake and pre-concentration of analytes in a binding gel and is used to measure dissolved metals and some organic compounds. The utility of novel silica-bound sorbents (C8, C18, mixed phases) as DGT binding gels for the sequestration of organotins in the marine environment was the primary focus of work in this project. The C8 sorbent showed the optimum performance in the uptake and recovery of organotins across pH, ionic strength and in filtered sea water. It was used subsequently as the binding layer in DGT sediment devices (160 mm × 34 mm) overlaid with a mixed-cellulose ester membrane (0.45 μm) as the single diffusion layer. These were used to investigate pore water mobilisation and concentrations of organotins in coastal sediment cores collected from a contaminated site. Organotins demonstrated a non-sustained uptake scenario, with DGT flux and freely dissolved concentrations in pore water measured to decline at 1 cm depth intervals over deployments of 2-28 days. Using time series, concentrations in pore water at t = 0 were calculated providing empirical pore water depletion curves for sediment cores. Using standard laboratory instrumentation (i.e. gas chromatography-mass spectrometry) low limits of detection were achieved (TBT = 0.4 ng L-1 after 2 weeks of sampling).
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Szkandera, Roman. "Testování modifikovaných sorbetů Iontosorb pro užití v technice difúzního gradientu v tenkém filmu (DGT)." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216360.
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6-mercaptopurine was joined by diazotation and copulation reactions on Iontosorb AV. Presence of thiol groups in modified resin was showed by infrared spectrometry. Amount of thiol groups was determined by iodometric titration. Resin gel was preparated from modified resin and agarose and both of them were tested for mercury determination by DGT technique.
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Soares, Jose Antonio. "An investigation of early diagenetic processes in marine coastal environments by the diffusive gradient in thin films (DGT) technique." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246223.
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Trávníčková, Jana. "Transport kovů v systému půda/rostlina. Porovnání metody aktivního a pasivního vzorkování (Technika difúzního gradientu v tenkém filmu)." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233341.
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The doctoral thesis deals with comparison between copper uptake by radish (Raphanus sativus L.) and concentration of copper measured by a DGT-device and concentration of copper obtained by extraction with generally used extraction agents (HNO3, NaNO3 and water). Plants were cultivated in pot experiments on a tested non-treated and gradually spiked soil. The amount of copper was determined in various part of radish (whole plant, above- and below-ground part) after mineralization in the APION mineralizer by ET – AAS. The highest concentration was in belowground part, especially in root tissues and sheel of root bulb. It confirms copper is associated with cell walls. The amount of copper taken by radish up does not pass beyond sanitary standards not even in spiked soils and consummation of radish is not unhealthy. Good correlations were found between copper concentration in radish and the amount of copper extracted with HNO3, NaNO3 and water and the amount found in soil solution. Results of extraction with HNO3 confirmed the amount of copper was stable in spiked soils during the pot experiments. The DGT experiments have shown that the rate of resupply from the solid phase to soil solution is constant during the deployment time. Whereas the release of copper decreases after 24 hours in natural soil. Copper added to soil in form of cupric ions is present in the different form after one month-equilibration than copper present in unspiked soils. The results obtained by DGT measurements were approximately up to two orders of magnitude lower than copper concentration obtained by leaching with sodium nitrate. The extraction with sodium nitrate does not provide true reflection of metal availability to plant root system and soil microorganism. High values of correlation coefficients (R2 > 0,9) were found between concentration of copper in radish plant and the concentration of copper in soil solution measured by DGT technique. Concentration of copper in soil solution was three times higher than concentration measured by DGT technique. Soil solution contains species of copper that are not measured by DGT technique and available to plants. Concentration of metals obtained by DGT measurements is more closely to real concentration of bioavailable forms of metal in soil. Therefore it is possible to recommend the DGT technique as a technique for determination of bioavailable forms of copper in soils.
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Němec, Tomáš. "Formy vybraných kovů ve vodních systémech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216358.
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The diffusive gradient in thin films technique (DGT) was used to measure concentration of labile metal-species (Cu, Ni, Pb) in the waste water from Faculty of Chemistry, Brno University of Technology.
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Szkandera, Roman. "Vývoj techniky difúzního gradientu v tenkém filmu (DGT) pro stanoveni rtuti ve vodných systémech." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233340.
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The theoretical part of this doctoral thesis deals with determination of mercury and its species in aquatic systems. Special attention is paid to the use in situ sampling technique diffusive gradients in thin films technique (DGT) and its development. Current resin gels used for determination of mercury by DGT technique Duolite GT-73, Chelex-100 and Spheron-Thiol are described. Moreover, new types of resin gels including Iontosorb AV modified by imidazole or 6-mercaptopurine and commercially available titanium dioxide. Preparations of resin gels and their basic tests in model solution according to DGT Research are described. Mercury accumulation in relation to time and basic recovery test were tested and capacity of resins was determined. All tested resins meet the requirements of basic DGT Research tests and relative standard deviations of mercury in recovery tests were lower than 10 %. The sorption capacity of resins varied from 1,5 to 6 µmol.l-1 and decreased in following order: Duolite GT-73 > ISAV-IM > Chelex-100 > Spheron-Thiol > TiO2 > ISAV-MP. Mercury sorption on resins was investigated under conditions similar to those in natural waters. It was found that the ionic strength commonly occurring in natural waters does not affect the determination of mercury. The presence of chlorides significantly affects the determination of mercury using DGT with titanium dioxide and therefore this sorbent can not be recommended for the determination of mercury in sea waters. The accumulated amount of mercury, depending on the pH shows that all the sorbents can be used in natural waters with pH in the range form 4 to 8. Mercury sorption is most affected by the presence of humic acids, especially at ion-exchange resins containing other than thiol functional groups. The exception is titanium dioxide for which physical sorption of humic acid metal complexes is typical. Cadmium and copper in model solutions in the molar balance of the excess mostly influenced the sorption of mercury on Chelex-100 and Spheron-Thiol resins. After laboratory tests, the DGT units with studied sorbents were used for the determination of mercury in natural waters of South Moravia (Svratka, Jihlava and Svitava river). Mercury concentration determined using DGT units containing Duolite GT-73 resin was comparable to the total dissolved concentration of mercury in river water provided by direct determination using AAS technique. Order of magnitude smaller concentrations than the total dissolved mercury concentration were found using DGT containing Spheron-Thiol and ISAV-MP resins. These sorbents are probably able to capture only mercury present in the form of labile complexes. This can be used for speciation analysis if more DGT units with different resins are deployed together. Subtracting the measured DGT Spheron-Thiol or ISAV-MP concentrations from the DGT Duolite GT-73 concentration, information about the amount of mercury present in the form of stabile complexes can be obtained. The amount of mercury determined after application of DGT units containing ISAV-IM, Chelex 100 or TiO2 can probably represent the mercury fraction bound in even weaker complexes than fraction determined by Spheron-Thiol and ISAV-MP DGT.
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Kobayashi, Takahiro. "Development and application of the DGT technique for the measurement of nitrate, ammonia and phosphate in natural waters, sediments and soils." Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302435.
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Turner, Geraldine Sarah Clinton. "The application of the passive sampling technique diffusive gradients in thin-films (DGT) to the measurement of uranium in natural waters." Thesis, University of Portsmouth, 2013. https://researchportal.port.ac.uk/portal/en/theses/the-application-of-the-passive-sampling-technique-diffusive-gradients-in-thinfilms-dgt-to-the-measurement-of-uranium-in-natural-waters(107c3ce9-2c00-435f-b241-0b668c36bf9b).html.
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This thesis describes the application of a passive sampler, Diffusive Gradient in Thin Films (DGT), to the measurement of uranium in natural waters. Four resins (Chelex-100, manganese dioxide [MnO2], Diphonix® and MetsorbTM) were trialled with the DGT device. In freshwater environments, the MetsorbTM accumulated uranium in line with the DGT equation for 7 d with an acuracy of 75%; Chelex-100 did not accumulate uranium past 2 d; MnO2 accumulated up to 75% of that predicted by the DGT equation for 4 d; and the Diphonix® accumulated uranium for 7 d with an accuracy of ~100%. None of the resins tested in this study accumulated uranium in a marine setting in line with DGT predicted values past 2 d. The application of DGT to regulatory environmental monitoring schemes was investigated with MetsorbTM. The MetsorbTM DGT devices were deployed for 7 days at a time over a 6 month period at two freshwater field sites. Fluctuations in water chemistry were monitored and the size of the diffusive boundary layer (DBL) was measured. The uranium accumulated by the MetsorbTM DGT showed close agreement with the grab samples. The size of the DBL was found to be significant, particularly in low flow conditions. This study showed that DGT could be used as a tool to both monitor radioncludes in the environment, and to obtain information on the speciation and organic interactions. The lability of uranium-humic acid complexes was also examined in this study. Initial data shows that the uranyl-humic complex is labile in low pH environments, but becomes increasingly kinetically limited the higher the pH and the higher the humic acid:uranium ratio. Data is also presented on the penetration parameter of the uranyl ion into the resin gel layer, and how this can be used to indicate lability. Lability is important in determining bioavailability and potential toxicity of uranium.
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Laera, Andreina. "Fate of trace elements during and after anaerobic digestion : a sequential extraction method and DGT technique to assess bio-accessible trace elements in digestate." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2011.
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Différentes interactions chimiques entre les éléments traces métalliques (ETM) et les composés organiques/inorganiques provenant du substrat et générées au cours du processus de digestion anaérobie détermineront la spéciation des ETM dans les digesteurs anaérobies. Après digestion anaérobie, les digestats sont exposés à des conditions d’oxydation qui peuvent favoriser un changement de la spéciation des ETM et par conséquent de leur bioaccessibilité pour les microorganismes du sol et les plantes lors de l’épandage des digestats sur des terres agricoles en tant qu’amendement organique. Plusieurs techniques ont été utilisées pour évaluer la mobilité, l'accessibilité et la biodisponibilité potentielle des ETM dans les digestats afin d'évaluer les risques pour l'environnement liés à l'utilisation du digestat en tant qu’amendement organique. L’objectif de cette thèse est d'évaluer une procédure d'extraction séquentielle et la technique DGT pour évaluer les ETM bio-accessibles dans des échantillons de digestat. Les échantillons ont été prélevés dans des installations industrielles de digestion anaérobie, traitant un mélange de déchets solides industriels et municipaux ou de boues d'épuration. Les ETM étudiés sont : Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Zn et W. Une procédure d'extraction séquentielle, conçue à l'origine pour le fractionnement de la matière organique (MO), a été mise en œuvre pour extraire simultanément la MO et les ETM dans un échantillon de substrat et de digestat. Il a été observé que plus de 50% des quantités totales d'As, Cd, Co, Fe, Mn, Ni et Zn étaient extraites avec les fractions de MO définies de manière opérationnelle dans les deux échantillons. Une extraction plus faible a été observée pour Al, Cr, Cu, Mo et Pb. Ces éléments étaient principalement présents dans la fraction de MO dissoute, où les ETM solubles sont probablement bio-accessibles pour l'absorption microbienne. De plus, une grande partie des éléments a été retrouvée dans la fraction minérale, qui était considérée faiblement bio-accessible. Cependant, la possibilité d'utiliser la méthode susmentionnée a été remise en question par suite de la faible efficacité d'extraction de certains ETM au cours de la procédure d'extraction. De plus, il a été reconnu que les réactifs chimiques utilisés au cours de la procédure d'extraction auraient pu favoriser la dissolution/précipitation des ETM, donc une modification de leur fractionnement. Par rapport aux mesures classiques de mesure des éléments dissous, la technique DGT augmente la sensibilité pour la mesure des ETM dans les boues d'épuration digérées. Cependant, il a été observé que le temps de déploiement des échantillonneurs DGT dans les boues d’épuration digérées devrait être soigneusement évalué. De plus, la matrice de digestat a réduit l’accumulation de certains ETM dans les échantillonneurs DGT. Par conséquent, les ETM labiles de la DGT (c'est-à-dire la plupart des espèces bio-accessibles) peuvent être correctement estimés à condition d'adapter soigneusement le temps de déploiement et d'effectuer une évaluation des effets de matrice dans les digestats. L’évolution temporelle de la concentration des ETM labiles peut être estimée. Par conséquent, l’effet de l’oxygénation des digestats sur la mobilité et la bio-accessibilité des ETM, y compris les fractions labiles et solubles, dans les boues d’épuration digérées a été étudié. L'exposition à l'air du digestat a favorisé la dissolution de Al, As, Co, Cr, Cu, Fe, Mn, Mo et Pb, suggérant une possible augmentation de leur mobilité qui pourrait probablement survenir lors du stockage du digestat dans des réservoirs ouverts ou lors de la manipulation avant l'épandage sur le sol. La fraction des éléments labiles n’augmente que pendant une aération prolongée (sauf pour Fe et Mn), ce qui suggère que leur bio-accessibilité à ne peut augmenter qu’après une aération importante comme celle supposée se produire lors de l’épandage du digestat sur les solsDifferent chemical interactions between trace elements and organic/inorganic compounds originating from the substrate and generated during the anaerobic digestion process will determine the speciation of trace elements in anaerobic digesters. After anaerobic digestion, digestates are exposed to oxidizing conditions which may favor a change of trace elements’ speciation and consequently bio-accessibility for soil microorganisms and plants when digestates are spread on lands as organic amendment. Several techniques were used to assess the mobility, accessibility, and potential bio-availability of trace elements in digestates for environmental risk assessments of digestate utilization as a soil fertilizer. The aim of this thesis is to evaluate a sequential extraction procedure and the diffusive gradients in thin films technique (DGT) to assess bio-accessible trace elements in digestate samples. Samples were taken from full-scale anaerobic digestion plants treating a mixture of industrial and municipal solid wastes or sewage sludge. The elements investigated include Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Se, Zn and W. A sequential extraction procedure, originally conceived for organic matter fractionation, was implemented to simultaneously extract organic matter and trace elements in a substrate and digestate sample. It was observed that more than 50% of total As, Cd, Co, Fe, Mn, Ni and Zn were extracted along with the operationally defined organic matter fractions in both samples. Whereas, a lower recovery was observed for Al, Cr, Cu, Mo and Pb. These elements were mainly found in the dissolved organic matter fraction where soluble trace elements are likely bio-accessible for microbial up-take. Moreover, a high portion of elements was found in the mineral fraction, which was considered poorly bio-accessible. However, the feasibility of using the aforementioned method was questioned following the low efficiency of extraction of certain trace elements during the extraction procedure. Moreover, it was acknowledged that chemical reagents employed during the extraction procedure could have promoted a dissolution/precipitation of trace elements and therefore a change in their fractionation. Therefore, DGT technique was tested to fractionate trace elements and it was observed that this technique increased the sensitivity of trace elements monitoring compared to conventional dissolved elements measurements in digested sewage sludge. However, it was observed that the DGT samplers’ deployment time in digested sewage sludge should be carefully evaluated. Additionally, the digestate matrix lowered the accumulation of some trace elements in the DGT samplers. Therefore, DGT labile trace elements (i.e. most bio-accessible species) can be correctly estimated provided a careful adaptation of the deployment time as well as an evaluation of the matrix effect is performed in digestate samples. Unless this, general trend of labile trace elements over time could be estimated such as the distribution of labile trace elements over time in digestate exposed to air. Therefore, the effect of atmospheric air on the mobility and bio-accessibility of trace elements, including labile and soluble fractions, in digested sewage sludge was investigated. The exposure of digestate to air promoted dissolution of Al, As, Co, Cr, Cu, Fe, Mn, Mo and Pb, suggesting that a possible increase in their mobility may likely occur during digestate storage in open tanks or handling before land spreading. Labile elements’ fraction increased only during an increase of aeration (except for Fe and Mn), suggesting that their short-term bio-accessibility can increase only after significant aeration as the one assumed to occur when digestate land spreading takes place
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Paříková, Lucie. "Rtuť v odpadních vodách." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216362.
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In the time period from November to April of the academic year 2007/2008 presence of mercury and its forms was monitored in the waste waters of Faculty of Chemistry, VUT in Brno. The level of mercury was determined as total mercury with help of the atomic absorption spectrometry method and in available forms by diffusive gradient in thin film technique.
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Fozard, Susan. "Development and applications of the DGT (diffusive gradients in thin-films) technique for the measurement of Mo and W in waters and soils." Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.654735.
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Molybdenum and tungsten are present in the environment as the oxyanions molybdate (MoOl-) and tungstate (WOll Measurements of available Mo and W in soils and waters have been stalled by the lack of a suitable technique. Diffusive gradients in thin films (DGT) is an in situ tool that allows the direct measurement of metal ions accumulated over a given time. This work provides the fIrst systematic investigation on the performance of DGT, containing a binding layer comprising of a single Feoxide reagent, for the measurement of Mo and W in soils and waters. The performance characteristics of DGT, were unaffected by solution conditions likely to be encountered in the environment (PH and ionic strength). DGT effIciently and effectively measured concentrations of labile Mo and W in streams and soils. In laboratory experiments complexation with humic substances was shown to occur with the strongest complexation being observed for HA. Toxicity assays showed that exposure to Mo and W resulted in weight loss, reduced reproduction and bioaccumualtion of Mo within the tissues of earthworms. Collectively these results showed that DGT, using Fe-oxide as the single binding layer, behaves predictably over a wide range of solution conditions and is a suitable and robust passive sampling technique for the measurement of Mo and W in natural environments.
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Li, Weijia, and n/a. "Development of New Binding Phases for Speciation Measurements of Trace Metals with the Diffusive Gradients in Thin Films Technique." Griffith University. School of Environmental and Applied Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040504.150905.
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The recently developed technique of diffusive gradients in thin films (DGT) for speciation measurement of analytes in the environment was further developed through the development of series of new binding phases including poly(acrylamide-co-acrylic acid) copolymer hydrogel (PAM-PAA), poly(acrylamidoglycolic acid-co-acrylamide) (PAAGA-PAM) hydrogel, the Whatman P81 cellulose phosphate ion exchange membrane (P81) and a liquid binding phase of poly(4-styrenesulfonate) (PSS). A new diffusion layer, cellulose dialysis membrane, was also employed for the liquid binding phase DGT. PAM-PAA copolymer hydrogel was prepared by the controlled hydrolysis of polyacrylamide (PAM) in an alkaline solution of 10% sodium hydroxide. The capacity of the copolymer hydrogel to bind various metal ions was tested under a range of uptake conditions. Ions such as Cu2+ and Cd2+ were bound more strongly to the copolymer hydrogel than the competing ions such as Na+, K+, Ca2+ and Mg2+. Metals bound to the copolymer hydrogel can be efficiently eluted in 2 M HNO3 solution (>94%). Application of this new binding material to DGT technique was validated in a synthetic lake water (Windermere, Lake District, UK) with a recovery of 99.0% for Cu2+. PAAGA-PAM hydrogel was prepared by copolymerising 2-acrylamidoglycolic acid with acrylamide. The metal ion binding properties of the hydrogel were characterised for Cu2+, Cd2+ and competing ions under various experimental conditions. The hydrogel was shown to bind Cu2+ and Cd2+ strongly under non-competitive binding conditions, with binding capacities of 5.3 and 5.1 micromol cm-2, respectively. The binding capacity of each metal decreased, under competitive binding conditions (with a range of metal ions present at 17.8 mN), to 1.3 and 0.17 micromol cm-2, respectively, indicating a strong selective binding towards Cu2+. The metal ions were readily recovered (>94%) by eluting with 2 M HNO3. Finally, the copolymer hydrogel was tested as a binding phase with the DGT technique. A linear mass vs. time relationship was observed for Cu2+ in Windermere water with a recovery of close to 100%. The use of a commercially available solid ion exchange membrane (P81) as the binding phase in DGT analysis was demonstrated. P81 is a strong cation exchange membrane. Its performance characteristics as a new binding phase in DGT measurement of Cu2+ and Cd2+ were systematically investigated. Several advantages over the conventional ion exchange resin-embedded hydrogel based binding phases used in DGT were observed. These include: simple preparation, ease of handling, and reusability. The binding phase preferentially binds to transition metal ions rather than competing ions. Within the optimum pH range (pH 4.0 - 9.0), the maximum non-competitive binding capacities of the membrane for Cu2+ and Cd2+ were 3.22 and 3.07 micromol cm-2, respectively. The suitability of the new membrane-based binding phase for DGT applications was validated experimentally. The results demonstrated excellent agreement with theoretically predicted trends. The reusability of this binding phase was also investigated. Application of a liquid binding phase and a dialysis membrane diffusive layer were proposed for the first time. The binding phase was a 0.020 M solution of poly(4-styrenesulfonate) (PSS) polyelectrolyte using a specially designed DGT device. The binding properties of Cd2+, Cu2+, and a range of alkali and alkaline earth metal ions to the PSS solution were characterised. The PSS behaved like a cation exchanger with preferential binding to Cd2+ (6.0 micromole ml-1, log K = 9.0) and Cu2+ (2.5 micromole ml-1, log K = 8.1) under competitive binding conditions. The DGT devices were successfully validated for Cd2+ and Cu2+ in Windermere water. The speciation performance of the solid and liquid binding phases developed in this study was investigated in solutions containing ethylenediaminetetraacetic acid disodium salt (EDTA), humic acid (HA), glucose (GL), dodecylbenzenesulfonic acid (DBS) and tannic acid (TA) with Cu2+ and Cd2+. The ratios of labile metals over total metals were at good agreement with calculated theoretical values using Stability Constants Database. The results indicated that the DGT-labile concentration measured by DGT with these binding phases is essentially free metal ion concentration in the sample. All newly developed DGT binding phases were successfully applied for environmental speciation. The field deployments were carried out in both freshwater and salt-water test sites.
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Fernández, Gómez Cristal. "New insights on the biogeochemical cycle of mercury in freshwater environments. Development and application of the DGT technique for bioavailability assessment and studies of methylmercury photodegradation." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/279241.
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Mercury (Hg) is naturally present in the Earth’s crust, however the historical use of this metal by the human being has spread and increased its presence in the environment. Both inorganic and organic species can be found in aquatic ecosystems, which are very sensitive to Hg pollution. In anoxic waters and sediments, sulphate-reducing bacteria can convert inorganic Hg into methylmercury (MeHg), a very toxic organic form which has the ability to bioaccumulate and biomagnify throughout trophic chains. Thus, to assess the risk associated to Hg pollution, the development of techniques to monitor Hg levels in water is necessary, as well as investigating MeHg elimination pathways.
In this doctoral thesis, two aspects related to the biogeochemical cycle of Hg in freshwater were addressed. On one hand, a passive sampling technique –Diffusive Gradients in Thin films (DGT)– was developed both for determination of total Hg (THg) and MeHg in freshwater. Apart from providing a time-average Hg concentration, these samplers are able to measure the labile fraction of Hg, since they supposedly mimic biological membranes. Thus, the DGT technique is considered a good monitoring tool to estimate the bioavailability of Hg in water. On the other hand, MeHg photodegradation in freswhwaters dominated by dissolved organic matter (DOM) was studied.
Regarding the DGT technique, several preliminary tests were carried out both at the laboratory and in the field to test the validity of a commercial type of samplers to measure the labile dissolved Hg in continental waters. Later, the performance of this commercial type was compared to that of two in-house manufactured samplers; both of them with the same receiving gel consisting of a resin with 3-mercaptopropyl groups embedded in a polyacrylamide gel, but one with an agarose gel (A-DGT) and the other with polyacrylamide gel (P-DGT) as the diffusive layer. The uptake kinetics of Hg(II) and MeHg, both in the absence and in the presence of DOM, were studied. The diffusion coefficient, D, of Hg in the DGT diffusive layer varied among Hg species and also depended on the absence/presence of DOM in the solution. This confirms the need to use the Hg species of interest and simulate the characteristics of the water to be sampled when performing the DGT calibration if the aim is to accurately measure the labile Hg fraction. The P-DGT was chosen as the most appropriate to determine both THg and MeHg in natural waters. Thereby, this type of sampler was used in a case study to assess the removal, methylation and lability of Hg(II) in a experimental scale plant for wastewater treatment consisting in several constructed wetlands with different conformation in series.
With respect to the MeHg photodegradation issue, this phenomenon was studied in waters from a lake-wetland gradient in the boreal Sweden. The influence of DOM on this process by attenuating light, forming reactive oxygen species and binding MeHg to its thiol groups to form complexes, was examined. It was observed that the desmethylation rate constant (kpd Full Spectrum) varied significantly among the three studied waters, but the wavelength-specific rate constants (kpdPAR, kpdUVA and kpdUVB) were indistinguishable. Therefore, kpd PAR, kpd UVA and kpd UVB can be considered universal, at least in waters dominated by DOM and in which MeHg is complexed by organic thiols, if the photon fluxes of PAR, UVA and UVB radiation are separately determined and the wavelength-specific light attenuation by DOM is corrected for. Furthermore, the relationship between the photodegradation and bioavailability of MeHg was examined in an experiment involving different types of natural and artificial freshwater, but no apparent connection was observed between them.En aquesta tesi doctoral s'aborden dos aspectes relacionats amb al cicle biogeoquímic del Hg en aigües continentals. Per una banda, es va desenvolupar un sistema de mostreig passiu denominat gradients de difusió en capa fina (DGT), per la determinació del Hg total i del MeHg en fase aquosa. Aquests mostrejadors proporcionen la concentració mitjana de Hg durant el temps de mostreig i mesuren la fracció làbil de Hg. Per tant, la tècnica de DGT pot ser considerada una bona eina per avaluar la biodisponibilitat de Hg a l’aigua. D'altra banda, es va estudiar la fotodegradació de MeHg en aigües continentals. Pel que fa a la tècnica DGT, es van dur a terme diverses proves preliminars tant al laboratori com en el camp per provar la validesa d'un tipus comercial de mostrejador per mesurar el Hg dissolt i col•loidal làbil en aigua dolça. Aquest es va comparar amb dos tipus de mostrejadors DGT manufacturats al laboratori (A-DGT i P-DGT). Es van estudiar les cinètiques d’acumulació de Hg(II) i MeHg tant en absència com en presència de DOM. El P-DGT va ser escollit com el més apropiat per determinar ambdós THg i MeHg en aigües naturals i va ser utilitzat en un estudi de cas per avaluar l'eliminació, metilació i labilitat de Hg(II) en una aiguamoll construït a escala experimental pel tractament d’aigües residuals urbanes. La fotodegradació de MeHg va ser estudiada en aigües d'un gradient llac-aiguamoll en la Suècia boreal; i es va evaluar la influència de DOM en el procés. Es va observar que la constant de velocitat de fotodesmetilació (kpd Full Spectrum) va variar significativament entre les aigües estudiades, però les constants específiques per a cada longitud d'ona (kpdPAR, kpdUVA and kpdUVB) van ser indistingibles. Per això, kpdPAR, kpdUVA and kpdUVB poden ser considerades universals en aigües amb un alt contingut en DOM i on el MeHg estigui complexat per grups tiol orgànics. Finalment, amb la utilització de la tècnica DGT es va estudiar la possible influència que pot existir entre la fotodegradació i la biodisponibilitat de MeHg en diversos tipus d'aigues dolces naturals i artificials, però no es va observar cap connexió aparent entre elles.
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Turull, López Marta. "Novel developments in the Diffusive Gradient in Thin films (DGT) technique for the determination of bioavailable mercury and other trace metals in aquatic and terrestrial environments." Doctoral thesis, Universitat de Girona, 2019. http://hdl.handle.net/10803/668780.
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This thesis is focused on the use of the Diffusive Gradient in thin film (DGT) technique for the analysis of bioavailable mercury and other trace metals in water and soil. Homemade DGT devices using a selective ion-exchange resin, and a polyacrylamide gel as the diffusive layer using an open resin (>5 nm), have been used to determine the labile Hg in different aquatic systems, concretely in the Ebro river (Spain) and Tully river (Australia). Besides, a new design of DGT using a bis-acrylamide as a restricted layer (<1 nm) has been performed to determine different species of Hg in agricultural soils. On the other hand, using Chelex-100 as the resin in the DGT devices allowed the analysis of bioavailable trace metals and further correlation with the plant uptake, specifically by lettuces (Lactuca sativa)Aquesta tesi està basada en l’aplicació de la tècnica de Gradient de Difusió en capa fina (DGT) per a l’avaluació de la biodisponibilitat del mercuri i altres metalls en agua i sòl. Es van realitzar dispositius DGT al laboratori basats en una resina selectiva, juntament amb poliacrilamida com la capa de difusió, anomenat de “capa oberta” (>5 nm), utilitzats per a la determinació de mercuri biodisponible en diferents sistemes aquàtics, concretament en el riu Ebre (Espanya) i el riu Tully (Austràlia). A més, es va dur a terme un nou disseny de dispositiu DGT utilitzant bis-acrilamida, anomenat de “capa restringida” (<1 nm), per a la determinació d’espècies inorgàniques de mercuri en sistemes agrícoles. Per altra banda, s’ha utilitzat la resina Chelex-100 per a l’estudi de la biodisponibilitat d’altres metalls a més de correlacionar els resultats obtinguts amb l’absorció de metalls en planta, concretament en enciams (Lactuca sativa)
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Májska, Milada. "Role sedimentů jako zdroje nebo úložiště znečištění rtutí, geochemická studie." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233329.
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Rtuť je v přírodě přirozeně se vyskytujícím toxickým prvkem, jehož globální emise jsou ovlivňovány zejména antropogenními zdroji znečištění. Obrovský globální nárůst v usazování rtuti, zejména ve vodných ekosystémech, byl zaznamenán současně s počátkem průmyslové revoluce. Sedimenty jsou posledním místem úložiště nejrůznějších komplexů rtuti. Rtuť však zde může být přeměněna na toxičtější organickou formu, methylrtuť, pomocí transformačních procesů kontrolovaných různými fyzikálními, chemickými, ale i biologickými faktory. Navíc mohou být specie rtuti remobilizovány ze sedimentů pomocí difuze a resuspenzace a tak se sedimenty mohou stát i potenciálním zdrojem rtuti. Proces bioakumulace a bioobohacování tak pokračuje v potravním řetězci, ve kterém se člověk, i další zvířata, stává konzumentem methylrtuti. Stanovení celkové koncentrace rtuti není dostačující k porozumění osudu rtuti v přírodním prostředí a tak stanovení MeHg poskytuje nezbytnou doplňující informaci. Dostatečně citlivá a přesná analytická metoda pro stanovení specií rtuti je nezbytným nástrojem environmentální chemie. Metody vhodné pro stanovení specií rtuti v sedimentech jsou popsány v části metodologie disertační práce. Metoda stanovení methylrtuti v sedimentech pomocí automatické Headspace vybavené pastí („trap“) a spojené s plynovou chromatografií a fluorescenční detekcí je zde také popsána. Zvláštní pozornost je také věnována potřebám zásad čistého vzorkování, skladování vzorků a přípravě vzorků před samotou analýzou, jakož i samostatné části věnující se terénní studii rtuti a methylrtuti v sedimentech vytipovaných lokalit. Sedimenty jižní Moravy a severní Francie jsou srovnány z hlediska znečištění rtutí. Specie rtuti a další ukazatele (Fe, Mn, S) byly analyzovány v sedimentech, pórové vodě a povrchové vodě řek Dele a Lys (Francie) a Jihlava a Morava (Česká republika). Z hlediska posouzení vodních ekosystémů a jejich znečištění rtutí, je vhodné znát koncentraci rtuti v pórové vodě a posoudit dostupnost rtuti ze sedimentů. Technika difuzního gradientu v tenkém filmu je vhodným způsobem jak stanovit koncentraci rtuti v pórové vodě sedimentů. Do roku 2005 bylo použití této techniky pro měření rtuti značně limitováno. Ale nedávný pokrok především v dostupnosti možných sorpčních gelů vhodných pro stanovení rtuti umožnilo využití této techniky i pro stanovení rtuti. Byly použity různé sorpční gely: Spheron.Thiol, Duolite GT-73 a TiO2. Řeka Dele představuje past enormního množství antropogenní rtuti pocházející z průmyslových zdrojů a je považována za potenciální významný zdroj methylrtuti pro okolní prostředí a živé organismy především. Poslední část dizertační práce se zabývá aplikací dobře zavedeného experimentu využívajícím stabilní isotopy ke studiu metylačních a demethylačních procesů v sedimentech řeky Dele. Obohacené stabilní značkovače rtuti v anorganické formě (199Hg) and methylované formě (201MeHg) byly přidány do sedimentů. Tyto označené specie rtuti tak pomohly sledovat osud specií rtuti a vypočítat rozsah jejich přeměny v průběhu experimentu.
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Abdallah, Abdallah Sabry. "Investigation of New Techniques for Face detection." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33191.
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The task of detecting human faces within either a still image or a video frame is one of the most popular object detection problems. For the last twenty years researchers have shown great interest in this problem because it is an essential pre-processing stage for computing systems that process human faces as input data. Example applications include face recognition systems, vision systems for autonomous robots, human computer interaction systems (HCI), surveillance systems, biometric based authentication systems, video transmission and video compression systems, and content based image retrieval systems.
In this thesis, non-traditional methods are investigated for detecting human faces within color images or video frames. The attempted methods are chosen such that the required computing power and memory consumption are adequate for real-time hardware implementation. First, a standard color image database is introduced in order to accomplish fair evaluation and benchmarking of face detection and skin segmentation approaches. Next, a new pre-processing scheme based on skin segmentation is presented to prepare the input image for feature extraction. The presented pre-processing scheme requires relatively low computing power and memory needs. Then, several feature extraction techniques are evaluated. This thesis introduces feature extraction based on Two Dimensional Discrete Cosine Transform (2D-DCT), Two Dimensional Discrete Wavelet Transform (2D-DWT), geometrical moment invariants, and edge detection. It also attempts to construct a hybrid feature vector by the fusion between 2D-DCT coefficients and edge information, as well as the fusion between 2D-DWT coefficients and geometrical moments. A self organizing map (SOM) based classifier is used within all the experiments to distinguish between facial and non-facial samples. Two strategies are tried to make the final decision from the output of a single SOM or multiple SOM. Finally, an FPGA based framework that implements the presented techniques, is presented as well as a partial implementation.
Every presented technique has been evaluated consistently using the same dataset. The experiments show very promising results. The highest detection rate of 89.2% was obtained when using a fusion between DCT coefficients and edge information to construct the feature vector. A second highest rate of 88.7% was achieved by using a fusion between DWT coefficients and geometrical moments. Finally, a third highest rate of 85.2% was obtained by calculating the moments of edges.Master of Science
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Shuttleworth, Sarah M. "The application of gel-based sampling techniques (DET and DGT) to the measurement of sediment pore-water solutes at high (mm) spatial resolution." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369497.
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Muradagha, Rafea. "A modified DFT technique for linear phase measurement." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0005/MQ45336.pdf.
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Rio, Jérémy. "Modélisation à l'échelle atomique de Cycloparaphénylènes avec les techniques ab initio." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4078/document.
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Le travail de cette thèse porte sur l’étude à l’échelle atomique des molécules de Cycloparaphénylènes ([n]CPPs) et leurs dérivés, par modélisation ab initio (calculs par DFT/LDA). La première étude a été de regarder la stabilité de ces anneaux lors de leurs fonctionnalisations par des halogènes et les changements structuraux induits. La notion importante d’énergie de courbure a été soulevée pour trouver de nouvelles routes de synthèse. L’encapsulation de fullerène C60 à l’intérieur des [10]CPPs est une part très importante de cette thèse, avec plus particulièrement l’interaction entre le dimère d’azafullerène (C59N)2 et deux [10]CPPs. Les interactions supramoléculaires et l’alignement de deux [10]CPPs sur ce dimère ont été regardés théoriquement mais aussi expérimentalement grâce à une collaboration avec deux équipes de recherches en Allemagne et en Grèce. La possibilité d’alignement des [10]CPPs a conduit à l’étude de la fonctionnalisation de ces molécules dans le but de les connecter avec différents ponts de type aromatique, polymère ou métallique pour former une nouvelle famille de pseudo-nanotubes composé de [10]CPPs connectés. Selon les connexions utilisées, les propriétés de conduction des pseudo-nanotubes varient de semi-conducteur à large gap jusqu’à des structures métalliques. Dans ce manuscrit, les interactions entre les [n]CPPs et les nanotubes de carbone ont été étudiés pour former des structures où le [n]CPP interagit à l’intérieur ou autour du nanotube de carbone. Dans ce cadre, l’étude de la rotation du [n]CPP montre une très faible force de frottement et permet ainsi de prévoir une rotation ultra rapide du CPPThe work in this thesis concerns the study at the atomic scale of Cycloparaphenylene ([n]CPP) molecules and their complexes and derivatives, using ab initio modeling methods (DFT/LDA). I initially look at the stability of these molecular rings when functionalized by halogens, and the structural changes induced. The important notion of curvature energy is raised to find new synthesis routes. The encapsulation of C60 fullerene inside [10]CPPs is a very important part of this work and more particularly the interaction between the azafullerene dimer (C59N)2 and two [10]CPPs. This allowed us to look at supramolecular interactions and the alignment of two [10]CPPs on this dimer both theoretically and experimentally, through collaboration with research teams in Germany and Greece. The possibility of templated alignment of [10]CPPs leads to a study on the functionalization of these molecules with the aim of connecting them together with various connectors, for example with aromatic species, polymers or metals to form a new family of pseudo-nanotubes composed of multiply inter-linked [10]CPPs. Depending on the connections used, the conduction properties of the 'pseudo-nanotubes' can vary from wide-gap semiconductors to metallic structures. I also show in this manuscript, that [n]CPPs and carbon nanotubes can interact to form structures where the ring is encapsulated inside or around the carbon nanotube. In this context, the study of the rotation of cycloparaphenylene demonstrate a very low frictional force and thus predict ultra-rapid CPP rotation
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Wagner, Philipp. "Modélisation du graphène avec les techniques ab initio." Nantes, 2013. http://www.theses.fr/2013NANT2011.
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Le travail de cette thèse porte sur l'étude du matériau graphène et de nanostructures dérivées, par modélisation ab initio. L'influence des terminaisons chimiques des bords du feuillet graphène (armchair, zigzag et Klein, en considérant aussi des reconstructions possible) a été étudiée. En l'absence de terminaisons, une nouvelle configuration stable «repliée» a été identifiée; qui correspond à la création de structure nanotube le long des bords du feuillet. Une étude des bords hydrogénés a été effectuée, qui montrait des nouvelles configurations de bords Klein reconstruites énergétiquement favorable. En outre, les bords hydrogénés joueront un rôle clef dans les processus de croissance du graphène, et d'éventuels modèles de croissance adaptés via l'addition des dimères de carbone sont proposés. Des terminaisons plus complexes sur des nanorubans de graphène de type armchair de 4 à 25 Å de largeur ont été modélisées également, par exemple impliquant -OH (hydroxyle). L'influence sur la structure et les propriétés électronique, chimique et mécaniques des nanorubans a été étudiée. Cette partie a conduit à rediscuter la notion de module de Young de nanofeuillets (graphène, BN, MoS2, MoTe2 etc. ). Notamment ce travail propose une définition de «volume à prendre en compte» sur la base d'une densité électronique moyenne. Cette nouvelle approche offre un cadre transférable sous-jacent pour calculer le module de Young, et donc de pouvoir extrapoler correctement les valeurs entre le graphène, des nanotubes de carbone et du graphite. Le concept a aussi été étendu à des polymères organiquesIn this thesis graphene and related nanostructures were studied, using density functional ab initio modelling techniques. The influence of different edge terminations has been investigated for typical pristine graphene edges (armchair, zigzag and Klein) and several reconstructed edge configurations. For unterminated graphene edges a new stable folded back edge has been identified, creating a nanotube along the graphene edge. A systematic study of hydrogenated edges was performed, and new favourable reconstructed Klein edge configurations were found. Furthermore hydrogenated edges are expected to play an important role for graphene growth processes, and thus possible adapted growth models via carbon dimer addition are proposed. Next more complex edge functionalisations such as hydroxylated (-OH) edges were studied, in particular modelling thin 4 - 25 Å wide armchair graphene nanoribbons. Notably the influence on structural, electronic, chemical and mechanical properties has been investigated. This promises new routes towards controlled design of specific nanoribbon properties. Finally the in-plane Young’s modulus of various nanosheets (including graphene, BN, MoS2, MoTe2 etc. ) were calculated. In this context a new geometry independent volume definition for nanoobjects has been developed, based on the average electron density. This new approach offers a transferable underlying framework to calculate the Young’s modulus, and thus values correctly extrapolate for example between graphene, carbon nanotubes and bulk graphite. The concept was further extended to organic polymers
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Kaewkham-ai, Boonsri. "Improving Dst index prediction using Kalman filtering techniques." Thesis, University of Sheffield, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486700.
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Over the past few decades, short term Dst index prediction using different techniques have been proposed since effects of space weather cause many problems on operational systems on Earth. Using input-output methods, the coupling function between solar wind parameters and Dst index is found to be nonlinear. In practice, observed data have been provided in almost real time but this is very noisy. To address noisy data and nonlinear dynamics, Kalman filtering techniques are used. Furthermore, the measurement noise which is derived from the error between provisional Dst and quick look Dst is found to be non white and modelled using an ARMA structure. Four existing models are chosen and a new model using NARX structure is proposed. Parameter estimation using joint and dual estimation techniques is studied. A comparison between models with Kalman filtering techniques and models alone is made and it is found that Kalman filtering methods can improve prediction performance and reduce prediction error.
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Mei, Liming, and james mei@ieee org. "A DWT Based Perceptual Video Coding Framework - Concepts, Issues and Techniques." RMIT University. Electrical and Computer Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090506.103244.
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The work in this thesis explore the DWT based video coding by the introduction of a novel DWT (Discrete Wavelet Transform) / MC (Motion Compensation) / DPCM (Differential Pulse Code Modulation) video coding framework, which adopts the EBCOT as the coding engine for both the intra- and the inter-frame coder. The adaptive switching mechanism between the frame/field coding modes is investigated for this coding framework. The Low-Band-Shift (LBS) is employed for the MC in the DWT domain. The LBS based MC is proven to provide consistent improvement on the Peak Signal-to-Noise Ratio (PSNR) of the coded video over the simple Wavelet Tree (WT) based MC. The Adaptive Arithmetic Coding (AAC) is adopted to code the motion information. The context set of the Adaptive Binary Arithmetic Coding (ABAC) for the inter-frame data is redesigned based on the statistical analysis. To further improve the perceived picture quality, a Perceptual Distortion Measure (PDM) based on human vi sion model is used for the EBCOT of the intra-frame coder. A visibility assessment of the quantization error of various subbands in the DWT domain is performed through subjective tests. In summary, all these findings have solved the issues originated from the proposed perceptual video coding framework. They include: a working DWT/MC/DPCM video coding framework with superior coding efficiency on sequences with translational or head-shoulder motion; an adaptive switching mechanism between frame and field coding mode; an effective LBS based MC scheme in the DWT domain; a methodology of the context design for entropy coding of the inter-frame data; a PDM which replaces the MSE inside the EBCOT coding engine for the intra-frame coder, which provides improvement on the perceived quality of intra-frames; a visibility assessment to the quantization errors in the DWT domain.
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Jouini, Ameur. "Méthodes et techniques de détection, identification et quantification des ultra-traces, application aux émetteurs alpha (Am et Pu)." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4063/document.
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La surveillance radiologique de l’environnement est un enjeu majeur pour étudier l Impact des activités industrielles et humaines mettant en œuvre des substances radioactives. Umalyse de l:tImet Pu présents à l’échelle des ultra-traces dans les sols et les sédiments (- mBq.kg-1) est souvent menée par spectrométrie (après séparation chimique. Ces méthodes souffrent de plusieurs inconvénients. Les objectifs de cette thèse sont par conséquent de simplifier la méthode de séparation et d'obtenir une limite de détection basse et un temps d’analyse relativement court en utilisant lICPMS-HR couplé au système d’introduction Apex-Q/ACM. Sur la base des données de la littérature, une méthode chimique utilisant une seule résine d’extraction chromatographique (DGA) est proposée pour isoler les concentrations ultra-traces d’Am et de Pu des différents types d'éléments interférents. La méthodologie proposée a été évaluée avec des solutions synthétiques avant l'utilisation de solutions de lixiviation d’échantillons préalablement analysés par spectrométrie alpha. La méthode retenue demande plusieurs procédure d’élution pour pouvoir séparer les majeurs, les interférents isobariques, les lanthanides, l’uranium et le thorium. Des rendements de chimie supérieurs à 90% pour Am et 60% pour Pu ont pu être mesurés. La robustesse de la méthode d’analyse a été validée avec un standard de référence certifié (AIEA-38S) .Enfin, le protocole analytique d’isolation et de dosage des ultra-traces d241Am et de 239Pu par ICP-MS-HR solution a été appliqué à des échantillons de sédiments échantillonnés dans l’estuaire de la Loire pour caractériser L’état radiologique du fleuveRadiological monitoring of the environment is a key issue for studying the impact of industrial and human activities using radioactive substances. The analysis of Am and Pu present at ultra-trace concentrations in soils and sediments (-mBq.kg-l) is often carried out by spectrometry after chemical separation. This procedure suffers from several drawbacks (multi-step separation process and long coun.tingtime). The objectives of this PhD are consequently simplify separation process and to achieve a low limit of detection with a relatively short analysis time using a high-resolution plasma source mass spectrometer HR-ICP-MScoupled to the introduction system Apex-Q/ACM. Base on literature data, a chemical methodology using a single column extraction chromatography resin (DGA) is proposed for isolating ultra-trace concentrations of Am and Pu from different types of interfering elements. The proposed methodology is assessed with synthetic solutions prior to the use of real leaching solutions previously analyzed by alpha spectrometry. The chosen method requires several elution procedures in order to separate the majors element, isobaric interferes, lanthanides, uranium and thorium. Recovery yields greater than 90% for Am and 60% for Pu were determined. The robustness of the analytical method was validated with a certified reference standard sample (IAEA-385). Finally, the analytical process for isolation and analysis of 241Am and 239Pu at ultra-trace concentration by ICP-MS-HRsolution was applied to samples of sediment taken from Loire estuary to characterize the radiological status of this river
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Gauthier, Évelyne. "Les Techniques de manipulation du roman populaire dit féminin." Lille 3 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb375985549.
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Gauthier, Évelyne. "Les techniques de manipulation du roman populaire dit féminin." Limoges, 1986. http://www.theses.fr/1986LIMO0503.
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Jowett, Simon. "A novel photogrammetric technique using DLT to measure golf shaft dynamics." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272754.
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Podber, David P. "Modeling strongly stratified flow using the dynamic grid adaptation (DGA) technique /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946776024051.
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Polo, Montes Carlos A. "The effect of cementation technique on the retention of adhesively cemented prefabricated posts." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007m/polomontes.pdf.
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Ellis, David Julian Peter. "Quantum dot single photon sources fabricated using novel processing techniques." Thesis, University of Cambridge, 2007. https://www.repository.cam.ac.uk/handle/1810/283834.
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This thesis details the development of a range of single photon source architectures, based on self-assembled InAs QDs. Unlike similar devices reported elsewhere [13, 67, 128, 187], the semiconductor heterostructures employed here are modified from their as-grown condition using a wet oxidation technique to convert aluminium-rich A1xGa1-x;As layers into aluminium oxide [38]. Oxidation can proceed laterally into a semiconductor heterostructure through exposed sidewalls, allowing the formation of regions of oxide within a device [33]. These layers exhibit a refractive index of around 1.5 and are excellent electrical insulators. In this work, oxide layers are employed in a number of different situations. In an electrically driven device, a ring of oxide was used to form a current aperture. This allowed an individual quantum dot to be electrically addressed. Oxide layers were employed to form high contrast mirrors in semiconductor pillar microcavities, from which enhanced spontaneous emission was observed. Oxide apertures were also integrated into Ga/As/A1xGa1-x;As microcavity structures, where the aperture can result in both optical and electrical confinement. Finally, rapid thermal annealing was investigated and demonstrated to be a useful tool to tune the emission energy and fine structure splitting of individual InAs quantum dots. A series of short anneals was shown to blueshift the exciton emission line of any selected quantum dot, accompanied by a reduction and inversion in polarisation splitting.
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Lindfors, Sarah. "Metal Fractionation in Snowmelt Runoff : A Comparison between Ultrafiltration and Diffusive Gradients in Thin Films (DGT) techniques." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65018.
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Urban runoff is a non-point pollution source deteriorating water quality of natural watersystems. The composition of urban runoff vary depending on land use, seasonal changes anddifferent surfaces that come into contact with the water. Urban runoff often contain metals andAl, Cd, Cr, Cu, Fe, Ni, Pb and Zn are of particular concern for the environment due to theirpotential toxicity. Metals in runoff can be present in different phases, associated with particles,colloids of different sizes or dissolved in the free phase. The different phases vary in size butalso overlap each other. Information about metal phases and species in runoff is essential tounderstanding metal transport and design runoff treatment systems.Membrane filtration followed by ultrafiltration is an established technique to distinguish theparticulate, colloidal and truly dissolved fractions. However, the “truly dissolved” fraction mayconstitute of the free phase, colloidal phase or both of them since the technique onlydiscriminates by size. Diffusive gradients in thin films (DGT) is a relatively new technique thatmeasures the labile fraction, sometimes referred to as the most bioavailable fraction. The labilefraction includes free metal ions and small complexes available to diffuse through a diffusivelayer under a reasonable period of time. Kinetically inert species are discriminated.The scope of this thesis was to investigate metal fractionation in snowmelt runoff from differenturban surfaces using two techniques, ultrafiltration and DGT. An additional aim was to studythe speciation described by the two techniques in the different types of runoff. Two types ofrunoff were sampled to conduct measurements on. Runoff from well-defined catchments (anindustrial area and a parking lot) and roof runoff from two roofing materials (zinc and coppersheet). In total, four runoff samples were membrane filtrated (pore size 0.45 μm) followed byeither ultrafiltration (delimiting 3 kNMWL) or DGT measurements in the laboratory. Analysisof metals was conducted in all steps and pH, electric conductivity, total suspended solids andtotal organic carbon was measured in the untreated samples.The results show that metal concentrations were generally higher in the catchment runoffcompared to the roof runoff with few exceptions, Cu and Pb from copper roof and Zn from zincroof. Regarding fractionation, the two types of runoff showed similarities when it came tometals mainly bound to particles. The metals that were abundant in several phases showeddifferent fractionations between the catchment runoff and the roof runoff. The metals releasedin roof runoff was to a higher extent found as free ions compared with the catchment runoff. Adiscussion was held about the different metal fractions and treatment possibilities. Comparingthe two techniques, the DGT measurements could be used to further interpret the results fromthe ultrafiltration regarding the colloidal and free phase.Dagvatten är en diffus föroreningskälla som försämrar vattenkvalitén hos naturliga vattendrag.Samansättningen av föroreningar i dagvatten kan variera beroende på markanvändning,årstidsvariationer och de olika ytor som dagvattnet kommer i kontakt med. Dagvatten innehållerofta metaller och Al, Cd, Cr, Cu, Fe, Ni, Pb och Zn kan vara toxiska för miljön i högakoncentrationer. Metaller i dagvatten kan förekomma i olika faser beroende på om de är bundnamed partiklar, kolloider av olika storlek eller om de är i löst fas. De olika faserna varierar istorlek men överlappar även varandra något. Kunskap om de olika faserna är viktigt förförståelsen om metallernas transportmekanismer och för att kunna designa eller förbättrareningssystem.Membranfiltrering följt av ultrafiltrering är en etablerad teknik för att särskilja partikulärtmaterial, kolloider och den sanna lösta fraktionen. Dock så kan den ”sanna lösta” fraktioneninnehålla antingen den kolloidala fasen, lösta fasen eller båda två eftersom tekniken baseras påstorleksfördelning. DGT (på engelska diffusive gradients in thin films) är en relativt ny tekniksom mäter den labila fraktionen som ibland benämns som den mest biotillgängliga fraktionen.Den labila fraktionen inkluderar fria metalljoner men även små komplex som kan diffunderagenom en diffusionsgel under en rimlig tidsperiod. Species som är kinetisk inerta kommer intemätas.Syftet med detta arbete var att undersöka metallfraktionering i snösmälts-avrinning från olikaurbana ytor genom att använda två tekniker, ultrafiltrering och DGT. Ett delmål var även attgranska de species som beskrevs av de två teknikerna i de olika typerna av dagvatten. Två olikaslags dagvatten samlades in och undersöktes. Dagvatten från väldefinierade avrinningsområden(ett industriområde och en parkeringsplats) och takavrinning från två takmaterial (zink- ochkopparplåtar). Totalt fyra dagvattenprover genomgick membranfiltrering (porstorlek 0,45 μm)följt av antingen ultrafiltrering (avgränsning 3 kNMWL) eller DGT mätningar i laboratoriet.Metallanalyser genomfördes i alla steg och pH, konduktivitet, suspenderade partiklar ochorganiskt kol mättes på det obehandlade proverna.Resultaten visade att de uppmätta metallkoncentrationerna var generellt högre i takavrinningenjämfört med dagvattnet från de hela avrinningsområdena. Dock med några undantag, Cu ochPb från koppartak och Zn från zinktak. När det kom till fraktionering fanns det likheter mellanavrinning från hela områden och från taken beträffande de metaller som till största del varbundna till partiklar. Däremot var det skillnad mellan de olika avrinningstyperna gällandefraktionering av metallerna som förekom i flera av faserna. I takavrinningen fanns det i störreutsträckning metaller som fria joner jämfört med avrinningsområdena. En slutsats var att DGTmätningarna kunde användas till att tolka resultaten från ultrafiltreringen när det gälldekolloidala och fria faserna.
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Soupart, Adrien. "Nouveau regard sur les propriétés photophysiques et photochimiques du complexe tris(2,2'-bipyridine) ruthénium II : apport de la DFT." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30143.
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Les complexes polypyridyles de ruthénium présentent un fort intérêt pour le développement d'applications dans les domaines du photovoltaïque, de la photocatalyse, de la détection, de la thérapie photodynamique ou, plus récemment, de la chimiothérapie photoactivée. Cependant, même pour [Ru(bpy)3]2+ qui est la référence pour ces complexes, de nombreuses observations expérimentales ne sont pas encore rationalisées. C'est pourquoi il est nécessaire de caractériser la topologie des surfaces d'énergie potentielles des états excités et les processus qui y sont à l'œuvre grâce aux méthodes de chimie théorique les plus modernes. La première partie de ce manuscrit présente les méthodes permettant l'exploration de ces surfaces et la rationalisation des propriétés photophysiques de [Ru(bpy)3]2+ et [Ru(tpy)2]2+ : simulation de spectres d'émission résolus en vibration, étude de la désactivation non radiative via la recherche de points de croisement entre les surfaces et l'évaluation des barrières d'énergie entre états par la méthode Nudged Elastic Band. La photoréactivité de [Ru(bpy)3]2+ n'a pas été étudiée d'un point de vue théorique et implique des "dark states" 3MC, sur lesquels très peu de données spectroscopiques sont disponibles, elle représente donc un vrai défi pour les théoriciens. Nous présentons dans une deuxième partie la caractérisation d'un véritable bassin 3MC avec une analyse Natural Bond Orbital des états s'y trouvant. Nous avons simulé les spectres d'absorption (UV-visible, XAS, IR) de tous les états excités triplets de [Ru(bpy)3]2+ que nous confrontons aux rares données expérimentales et leurs interprétations contradictoires afin de guider de futures études. Enfin, nous proposons la première étude mécanistique théorique complète d'une réaction de photosubstitution, la réaction modèle : [Ru(bpy)3]2+ + 2 MeCN → cis/trans [Ru(bpy)2(MeCN)2]2+ + bpy, en explorant les surfaces d'énergie potentielle fondamentales et excitées. Ce mécanisme multi-étapes séquentiel à deux photons nous a permis de rationaliser l'obtention majoritaire du photoproduit cisRuthenium polypyridyl complexes are of great interest for photovoltaic applications, photocatalysis, sensing, photodynamic therapy (PDT) or photoactivated chemotherapy (PACT). But even for the archetype [Ru(bpy)3]2+, not all experimental features have been unravelled yet. It is then mandatory to map the topology of the excited states potential energy surfaces and to characterize the associated processes with state-of-the-art theoretical methods. The first part of the manuscript describes the methods used to explore these surfaces and the rationalization of photophysical properties of two complexes, [Ru(bpy)3]2+ and [Ru(tpy)2]2+: simulation of Vibrationally Resolved Electronic emission Spectra (VRES), study of the non-radiative decay process through the optimization of Minimum Energy Crossing Points (MECP) and calculation of energy barriers and minimum energy paths using the Nudged Elastic Band method (NEB). The photoreactivity of [Ru(bpy)3]2+ has never been studied using theoretical methods. It involves 3MC dark states, poorly described by spectroscopic data. Therefore, it represents a great challenge for theoreticians. We describe in a second part a true 3MC basin and a Natural Bond Orbital analysis was conducted on the states composing it. We compare our simulations of various absorption spectra (UV-Vis, XAS, IR) of all triplet excited states of [Ru(bpy)3]2+ with the few experimental data available, and their contradictory interpretations, in order to provide a guide for future experiments. Finally, we propose the first and complete theoretical mechanism for a photosubstitution reaction using the model reaction: [Ru(bpy)3]2+ + 2 MeCN → cis/trans-[Ru(bpy)2(MeCN)2]2+ + bpy, by exploring fundamental and excited potential energy surfaces. This multi-step, sequential, two photon, mechanism allowed us to rationalize the preferential formation of the cis photoproduct
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Remersaro, Santiago. "On low power test and DFT techniques for test set compaction." Diss., University of Iowa, 2008. https://ir.uiowa.edu/etd/211.
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The objective of manufacturing test is to separate the faulty circuits from the good circuits after they have been manufactured. Three problems encompassed by this task will be mentioned here.
First, the reduction of the power consumed during test. The behavior of the circuit during test is modified due to scan insertion and other testing techniques. Due to this, the power consumed during test can be abnormally large, up to several times the power consumed during functional mode. This can result in a good circuit to fail the test or to be damaged due to heating.
Second, how to modify the design so that it is easily testable. Since not every possible digital circuit can be tested properly it is necessary to modify the design to alter its behavior during test. This modification should not alter the functional behavior of the circuit. An example of this is test point insertion, a technique aimed at reducing test time and decreasing the number of faulty circuits that pass the test.
Third, the creation of a test set for a given design that will both properly accomplish the task and require the least amount of time possible to be applied. The precision in separation of faulty circuits from good circuits depends on the application for which the circuit is intended and, if possible, must be maximized. The test application time is should be as low as possible to reduce test cost.
This dissertation contributes to the discipline of manufacturing test and will encompass advances in the afore mentioned areas. First, a method to reduce the power consumed during test is proposed. Second, in the design modification area, a new algorithm to compute test points is proposed. Third, in the test set creation area, a new algorithm to reduce test set application time is introduced. The three algorithms are scalable to current industrial design sizes. Experimental results for the three methods show their effectiveness.
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Arwood, Bryan Stuart. "The effectiveness of advanced oxidation techniques in degrading steroids in wastewater." Birmingham, Ala. : University of Alabama at Birmingham, 2010. https://www.mhsl.uab.edu/dt/2010m/arwood.pdf.
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Damodara, Eswar Keran C. "Clinical trial to determine the accuracy of prefabricated trays for making alginate impressions." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/damodara.pdf.
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Poulos, Konstantinos. "NEW TECHNIQUES ON VLSI CIRCUIT TESTING & EFFICIENT IMPLEMENTATIONS OF ARITHMETIC OPERATIONS." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/dissertations/1872.
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Testing is necessary factor to guarantee that ICs operate according to specifications before being delivered to customers. Testing is a process used to identify ICs containing imperfections or manufacturing defects that may cause failures. Inaccuracy and imperfections can be introduced during the fabrication of the chips due to the complex mechanical and chemical steps required during the manufacturing processes. The testing process step applies test patterns to circuits and analyzes their responses. This work focuses on VLSI circuit testing with two implementations for DFT (Design for testability); the first is an ATPG tool for sequential circuits and the second is a BIT (Built in Test) circuit for high frequency signal classification.There has been a massive increase in the number of transistors integrated in a chip, and the complexity of the circuit is increasing along with it. This growth has become a bottleneck for the test developers. The proposed ATPG tool was designed for testing sequential circuits. Scan Chains in Design For Testability (DFT) gained more prominence due to the increase in the complexity of the modern circuits. As the test time increases along with the number of memory elements in the circuit, new and improved methods are needed. Even though scan chains implementation effectively increases observability and controllability, a big portion of the time is wasted while shifting in and shifting out the test patterns through the scan chain. Additionally, the modern applications require operating speed at higher frequencies and there is a growing demand in testing equipment capable to test CMOS circuits utilized in high frequency applications.With the modern applications requiring operating speed at higher frequencies, there is a growing demand in testing equipment capable to test CMOS circuits utilized in high frequency applications. Two main problems have been associated when using external test equipment to test high frequency circuits; the effect of the resistance and capacitance of the probe on the performance of the circuit under test which leads to a faulty evaluation; and the cost of a dedicated high frequency tester. To solve these problems innovative test techniques are needed such as Built In Test (BIT) where self-evaluation takes place with a small area overhead and reduced requirements for external equipment. In the proposed methodology a Built In Test (BIT) detection circuit provides an efficient way to transform the high frequency response of the circuit under test into a DC signal.This work is focused in two major fields. The first topic is on VLSI circuit testing with two implementations for DFT (Design for testability); the first is an ATPG tool for sequential circuits and the second is a BIT (Built in Test) circuit for high frequency signal classification as explained. The second topic is focused on efficient implementations of arithmetic operations in arbitrary long numbers with emphasis to addition. Arbitrary-Precision arithmetic refers to a set of data structures and algorithms which allows to process much greater numbers that exceed the standard data types. . An application example where arbitrary long numbers are widely used is cryptography, because longer numbers offer higher encryption security. Modern systems typically employ up to 64-bit registers, way less than what an arbitrary number requires, while conventional algorithms do not exploit hardware characteristics as well. Mathematical models such as weather prediction and experimental mathematics require high precision calculations that exceed the precision found in most Arithmetic Logic Units (ALU). In this work, we propose a new scalable algorithm to add arbitrary long numbers. The algorithm performs bitwise logic operations rather than arithmetic on 64-bit registers. We propose two approaches of the same algorithm that utilize the same basic function created according to the rules of binary addition
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Fouratt, Melissa Amanda. "Application of Molecular Techniques to the Characterization of a Nitrifying Bioaugmentation Culture." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/33171.
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Nitrification is the biological process whereby ammonia is converted first to nitrite by ammonia-oxidizing bacteria, and then the nitrite is subsequently converted to nitrate by nitrite-oxidizing bacteria. Ammonia and nitrite levels are closely monitored during treatment of wastewater due to their toxicity to other biological processes. Sybron Chemicals, Inc., is a company that manufactures a nitrifying bioaugmentation culture (1010N) that is used to enhance the naturally occurring levels of biological nitrification. The microbial population of the 1010N product has been examined using a combination of conventional bacteriological methods and modern molecular techniques, with the goal of developing nucleic acid probes that can be used to detect the product in an environmental sample. Small regions of the 16S rRNA genes of the bacteria in 1010N (and two new nitrifying enrichment cultures) were amplified via the polymerase chain reaction (PCR) and analyzed via temperature gradient gel electrophoresis (TGGE). TGGE is a procedure that allows for separation and visualization of individual PCR products that are the same size, based on differences in their sequence. Two of the predominant PCR products in 1010N were purified from the TGGE gel matrix, reamplified via PCR, and sequenced to allow for phylogenetic analysis and nucleic acid probe design. Coincidentally, two strains (NS500-9 and MPN2) that had been isolated from the 1010N mixed consortium and grown in pure culture were found, via TGGE, to have identical 16S rRNA sequences to the PCR products under investigation. Nearly the full-length 16S rRNA genes from these two organisms were PCR amplified, cloned, and sequenced in order to provide a basis for more accurate phylogenetic analysis. The two dominant organisms in the 1010N product, NS500-9 and MPN2, were thereby found to be most closely related to Nitrosomonas and Nitrobacter, respectively, in the existing database. Using the nucleic acid sequences of the cloned DNA, organism-specific DNA probes were designed for both NS500-9 and MPN2. Unfortunately, difficulties were encountered in using the probes to monitor 1010N activity levels via quantitative dot blot hybridizations (rRNA-DNA). Therefore, efforts were redirected to using the TGGE semi-quantitatively with an internal PCR standard (Brüggeman, et al., 2000) to estimate original cell numbers of 1010N within a mixed consortium. This method was not applicable to our system due to substantial preferential binding of the primers to template other than the standard. Samples from a laboratory-scale bioreactor, bioaugmented with 1010N, were used in an attempt to correlate an increase in activity with a detectable shift in population via TGGE. No detectable shift in population was detected in these samples even though the system exhibited increased levels of nitrification. Therefore, the sensitivity of the TGGE system was also examined by determining the limits of detection when 1010N was present in activated sludge. In both whole cell spiking experiments and genomic DNA spiking experiments, it was found that 1010N must be present at a level of at least 5% of the total population in order to be detected. While this provides some information about microbial populations, in order to evaluate the biological activity of a system, nucleic acid probes should be used in a rRNA based study.Master of Science
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Edirisuriya, Amila. "Digital Hardware Architectures for Exact and Approximate DCT Computation Using Number Theoretic Techniques." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1363233037.
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Alrasheed, Waleed. "Time and Space Efficient Techniques for Facial Recognition." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6238.
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In recent years, there has been an increasing interest in face recognition. As a result, many new facial recognition techniques have been introduced. Recent developments in the field of face recognition have led to an increase in the number of available face recognition commercial products. However, Face recognition techniques are currently constrained by three main factors: recognition accuracy, computational complexity, and storage requirements. The problem is that most of the current face recognition techniques succeed in improving one or two of these factors at the expense of the others.
In this dissertation, four novel face recognition techniques that improve the storage and computational requirements of face recognition systems are presented and analyzed.
Three of the four novel face recognition techniques to be introduced, namely, Quantized/truncated Transform Domain (QTD), Frequency Domain Thresholding and Quantization (FD-TQ), and Normalized Transform Domain (NTD). All the three techniques utilize the Two-dimensional Discrete Cosine Transform (DCT-II), which reduces the dimensionality of facial feature images, thereby reducing the computational complexity. The fourth novel face recognition technique is introduced, namely, the Normalized Histogram Intensity (NHI). It is based on utilizing the pixel intensity histogram of poses' subimages, which reduces the computational complexity and the needed storage requirements.
Various simulation experiments using MATLAB were conducted to test the proposed methods. For the purpose of benchmarking the performance of the proposed methods, the simulation experiments were performed using current state-of-the-art face recognition techniques, namely, Two Dimensional Principal Component Analysis (2DPCA), Two-Directional Two-Dimensional Principal Component Analysis ((2D)^2PCA), and Transform Domain Two Dimensional Principal Component Analysis (TD2DPCA). The experiments were applied to the ORL, Yale, and FERET databases.
The experimental results for the proposed techniques confirm that the use of any of the four novel techniques examined in this study results in a significant reduction in computational complexity and storage requirements compared to the state-of-the-art techniques without sacrificing the recognition accuracy.Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Erdem, Rengin. "Ag2s/2-mpa Quantum Dots." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614384/index.pdf.
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Quantum dots are fluorescent semiconductor nanocrystals that have unique optical properties such as high quantum yield and photostability. These nanoparticles are superior to organic dyes and fluorescent proteins in many aspects and therefore show great potential for both in vivo and in vitro imaging and drug delivery applications. However, cytototoxicity is still one of the major problems associated with their biological applications.
The aim of this study is in vitro characterization and assessment of biological application potential of a novel silver sulfide quantum dot coated with mercaptopropionic acid (2-MPA). In vitro studies reported in this work were conducted on a mouse fibroblast cell line (NIH/3T3) treated with Ag2S/2-MPA quantum dots in 10-600 &mug/mL concentration range for 24 h. Various fluorescence spectroscopy and microscopy methods were used to determine metabolic activity, proliferation rate and apoptotic fraction of QD-treated cells as well as QD internalization efficiency and intracellular localization. Metabolic activity and proliferation rate of the QD treated cells were measured with XTT and CyQUANT®
cell proliferation assays, respectively. Intracellular localization and qualitative uptake studies were conducted using confocal laser scanning microscopy. Apoptosis studies were performed with Annexin V assay. Finally, we also conducted a quantitative uptake assay to determine internalization efficiency of the silver sulfide particles. Correlated metabolic activity and proliferation assay results indicate that Ag2S/2-MPA quantum dots are highly cytocompatible with no significant toxicity up to 600 &mu
g/mL treatment. Optimal cell imaging concentration was determined as 200 &mu
g/mL. Particles displayed a punctuated cytoplasmic distribution indicating to endosomal entrapment. In vitro characterization studies reported in this study indicate that Ag2S/2-MPA quantum dots have great biological application potential due to their excellent spectral and cytocompatibility properties. Near-infrared emission of silver sulfide quantum dots provides a major advantage in imaging since signal interference from the cells (autofluorescence) which is a typical problem in microscopic studies is minimum in this part of the emission spectrum. The results of this study are presented in an article which was accepted by Journal of Materials Chemistry. DOI: 10.1039/C2JM31959D.
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Rossignol, Karen. "Ensemble(s) pour affronter le risque pyrotechnique : étude sociologique de l’application des dispositifs de prévention des risques des établissements DGA en France." Thesis, Nancy 2, 2009. http://www.theses.fr/2009NAN21017/document.
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Cette recherche part de l'hypothèse générale que le concept de risque présente une grande portée heuristique pour analyser les comportements et les discours des individus dans les sociétés modernes. Elle s’appuie sur un travail de caractérisation des contextes institutionnels où le risque est présent, le terme "institution" étant défini comme une structure stabilisée de croyances, de représentations et de modes de conduites juridiquement ou culturellement institués et réglées par la collectivité. Ce travail a permis de poser deux hypothèses opératoires : - le risque est à la fois réel et construit : il faut prendre en compte la crainte du risque et la réalité du danger - le risque révèle les visions du monde à l'œuvre dans la Modernité : la signification du risque n’est pas seulement indigène à un groupe social mais s’inscrit dans un contexte social qui en fait un objet sociologique d’ordre général. La confrontation des hypothèses à l’expérience du terrain s’appuie sur une étude de l’application des dispositifs de gestion du risque au sein de l’Etablissement Technique de Bourges (ETBS), un centre d’essais de matériels d’armement du Ministère de la Défense. L’analyse des matériaux empiriques (40 entretiens, observation in situ, documents) rend complémentaires l'étude des aspects formels des institutions et l’étude du social comme vécu et expose les relations entre aspects objectifs et subjectifs du risque. Elle montre que le rapport au(x) risque(s) des acteurs des essais pyrotechniques de l’ETBS créé une attitude de responsabilisation à la fois individuelle et collective dans la gestion des risques, chacun, maillon dans une chaîne, contribuant à produire et à reproduire une "chaîne de responsabilité dans les essais pyrotechniques"This research is based on the general hypothesis that the concept of risk is very useful for analyzing and understanding behavior and discourses in modern societies. It draws on a work that characterizes the institutional contexts where risk appears, the term institution meaning a stabilized structure of beliefs, representations and behavior juridically or culturally constituted and established by the community. This work made it possible to propose two operational hypotheses: - Risk is both real and socially constructed : we must take into account the fear of risk and the reality of danger; - Risk is revealing of modern visions of the world in action: the significance of risk is not only indigenous to a social group but also part of a social context that makes risk a general sociological issue. The confrontation of these hypotheses with field experiences relies on a study of the implementation of risk management devices in the Etablissement Technique de Bourges (ETBS), a French military armament testing center. The analysis of empirical materials (field observations, interviews, and documents) combines the study of formal aspects of institutions and the study of the actors' point of view and exposes the relationship between objective and subjective aspects of risk. It shows that the staff involved in pyrotechnic tests at ETBS assume a collective and individual responsibility in the management of risk where each of the staff members is aware of his responsibilities to the others that contribute to produce and reproduce a "chain of responsibility in the pyrotechnic tests"
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Najib, Farrah Huthail. "Endodontic sealers their properties and effects on fiber post retention /." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/najib.pdf.
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Schmied, Marten. "Business Intelligence in Healthcare - Data Mining Techniques as a Possible Hospital Management Tool in Austria." Master's thesis, Vysoká škola ekonomická v Praze, 2016. http://www.nusl.cz/ntk/nusl-264283.
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Public healthcare provision is under increasing economic restraints making an efficient and sustainable managerial planning a necessity in the hospital sector. Business Intelligence is the extraction of business relevant knowledge in order to adjust and refine executive operations. On the free market industries have applied the according methods and software dedicated to the generation of Business Intelligence is offered by variety of companies. Data Mining, furthermore, describes the facilitation of algorithms in order to train programs to detect unseen patterns from huge amounts of data. Therefore mining techniques are suitable for adding to the business relevant knowledge, particularly as they can produce more accurate predictions. The thesis examined the status of Information Technology normally utilized in Austrian hospitals and simultaneously identified studies that apply Data Mining to a Hospital Information System to gain Business Intelligence. While the general level of Austrian Hospital Information Systems is well sophisticated, common challenges are present in a separation between clinical and administrative systems and their interfaces. For the Data Mining a majority of studies aims at medical improvements. Some applications were found to have good business relevant prospects but their feasible introduction into the practice needs additional fostering.
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Bachir, Alexia. "Characterization of quantum dot blinking and steric effects on fluorescence-based biophysical techniques." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19293.
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Semiconductor nanoparticles, or quantum dots (QDs) are being increasingly applied as luminescent labels in optical studies for biophysical and cell biological applications due to their unique spectroscopic properties as compared to traditional organic fluorescent probes. However, the intermittency in the fluorescence emission of QDs, commonly referred to as 'blinking', is suggested to affect transport studies using fluctuation correlation techniques. The QD size has also been suggested to be sterically limiting for some studies. The focus of this thesis work is to examine the photophysical blinking properties and steric size effects of QD nanoparticles and determine how they influence biophysical measurements of molecular transport and protein-protein interactions. The first goal was to characterize and account for QD fluorescence blinking in transport measurements utilizing the temporal image correlation spectroscopy (TICS) technique. Fluorescence correlation techniques monitor spontaneous fluctuations in fluorescence intensity from fluorophores as they enter and exit an optically defined focal volume. Transport coefficients are recovered by fitting a calculated autocorrelation function (ACF) to appropriate analytical models that accurately represent the underlying dynamics. The QD blinking is governed by power-law statistics, which describe processes that occur on multiple time scales. As a result, QD fluorescence blinking fluctuations contribute to the calculated ACF on all times scales and can not be decoupled from diffusion fluctuations. We first present temporal image correlation spectroscopy (TICS) measurements of single QDs and ensembles of immobile QDs as well as computer simulations of blinking point emitters to deterLes nanoparticules semi-conductrices, ou particules quantiques (PQs), sont utilisées de plus en plus fréquemment comme sondes luminescentes dans les domaines de la biophysique et de la biologie cellulaire pour leurs propriétés spectroscopiques uniques et avantageuses comparées aux sondes fluorescentes organiques.Toutefois, l'intermittence de l'émission fluorescente des PQs est censée affecter les études de transport dans les techniques de corrélation de variance.Il est proposé également que les grandeurs physiques des PQs limitent également les études qui les utilisent comme sondes.L'accent du travail de cette thèse consiste à étudier les propriétés de l'intermittence photophysique et des effets des grandeurs physiques des PQ pour déterminer comment ils affectent les mesures biophysiques du transport moléculaire et des interactions protéine-protéine.Le premier objectif était de caractériser et compenser l'intermittence de la fluorescence des PQ dans les mesures des migrations utilisant la technique de spectroscopie de corrélation temporelle dans les images (TICS).Les techniques de corrélation fluorescente étudient les variations spontanées de l'intensité fluorescente de particules fluorescentes qui entrent et qui sortent d'un volume défini par un focus optique.Les coefficients de transport sont obtenus par une régression d'une fonction d'auto-corrélation (FAC) en assumant un modèle approprié qui définit le transport du système.L'intermittence des PQs est régie par une probabilité qui décrit des processus qui surviennent sur plusieurs ordres de grandeur.Donc,les fluctuations de l'intermittence des PQs ne peuvent être découplées des fluctuations venant du transport et doivent être incorp
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Lao, Martínez Mireia. "Determination of free metal ion concentrations with the speciation techniques agnes and DMT." Doctoral thesis, Universitat de Lleida, 2019. http://hdl.handle.net/10803/667401.
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Des de fa molts anys, els metalls pesants s’han associat amb la contaminació i la toxicitat. Els podem trobar en el medi sota diferents formes químiques, però la comunitat científica coincideix en què els efectes tòxics que provoquen bàsicament depenen de la seva concentració lliure. Per això és important disposar de les tècniques adequades per quantificar-los. Aquesta tesi està centrada en la determinació de la concentració de metall lliure en mostres sintètiques i naturals mitjançant les tècniques analítiques d’AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) i DMT (Donnan Membrane Technique).
En la primera part d’aquest treball, s’ha estudiat el possible impacte en la tècnica electroanalítica AGNES degut a l’adsorció electròdica a través de diferents sistemes (Pb-taronja de xilenol, Cd- àcid poliacrílic i Cd-iodur entre d’altres). S’ha pogut confirmar que quan s’arriba a la situació especial d’equilibri d’AGNES al final de la primera etapa, l’existència d’altres processos d’equilibri (com l’adsorció) no afecta el senyal analític en cap de les variants d’AGNES. També, pels sistemes estudiats, els temps necessaris per arribar a l’estat d’equilibri no es veuen augmentats.
En la segona part, AGNES s’ha aplicat a l’estudi del sistema Zn-glutatió, primer en mostres sintètiques i després en extractes de l’arrel de la planta Hordeum Vulgare, considerant diferents models de complexació. En la determinació en mostres sintètiques, s’ha vist que els resultats teòrics de dos dels models coincideixen amb les determinacions d’AGNES. En el cas de les arrels, la concentració lliure de Zn determinada experimentalment ha estat bastant inferior que la predita teòricament, suggerint per tant la presència d’altres lligands (com altres fitoquelatines) apart del glutatió.
En la tercera part, s’ha estudiat la especiació inorgànica en el vi amb les tècniques AGNES i DMT. Les concentracions de metall lliure determinades en les mostres sintètiques de vi han sigut consistents amb les prediccions teòriques, però el temps necessari per arribar a l’equilibri DMT s’ha vist augmentat. En treballar amb les mostres de vi reals, aquest temps s’incrementa encara més. Pel que fa a la concentració lliure de Zn, els resultats obtinguts amb DMT, utilitzant K i Na com a ions de referència, (1.76 µmol L-1) coincideixen amb els corresponents obtinguts amb AGNES (1.7 µmol L-1). La tècnica DMT s’ha utilitzat també per determinar les concentracions de Fe, Mg i Ca.Desde hace años, los metales pesados se han asociado con la contaminación y la toxicidad. Los podemos encontrar en el medio bajo distintas formas químicas, pero la comunidad científica coincide en que los efectos tóxicos que provocan básicamente dependen de su concentración libre. Por ello es importante disponer de las técnicas adecuadas para cuantificarlos. Esta tesis está enfocada en la determinación de la concentración de metal libre en muestras sintéticas y naturales mediante las técnicas analíticas AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) y DMT (Donnan Membrane Technique). En la primera parte de este trabajo, se ha estudiado el posible impacto en la técnica electroanalítica AGNES debido a la adsorción electródica mediante diversos sistemas (Pb-naranja de xilenol, Cd-ácido poliacrílico y Cd-yoduro entre otros). Se ha confirmado que cuando se llega a la situación especial de equilibrio de AGNES al final de la primera etapa, la existencia de otros procesos de equilibrio (como la adsorción) no afecta a la señal analítica en ninguna de las variantes de AGNES. También para estos sistemas estudiados, el tiempo necesario para llegar al estado de equilibrio no se ve aumentado. En la segunda parte, AGNES se aplica al estudio del sistema Zn-glutatión, primero en muestras sintéticas y después en extractos de la raíz de la planta Hordeum Vulgare, considerando diferentes modelos de complejación. En la determinación en muestras sintéticas, se ha visto que los resultados teóricos de dos de los modelos coinciden con las determinaciones de AGNES. En el caso de las raíces, la concentración libre de Zn determinada experimentalmente ha sido bastante inferior a la predicha teóricamente, sugiriendo por tanto la presencia de otros ligandos (como otras fitoquelatinas) además del glutatión. En la tercera parte, se ha estudiado la especiación inorgánica en el vino con las técnicas AGNES y DMT. Las concentraciones de metal libre determinadas en las muestras de vino sintético han sido consistentes con las predicciones teóricas, pero el tiempo necesario para alcanzar el equilibrio DMT se ve aumentado. Al trabajar con las muestras de vino real, este tiempo todavía se incrementa más. En relación a la concentración libre de Zn, los resultados obtenidos con DMT, utilizando K y Na como iones de referencia, (1.76 µmol L-1) coinciden con los correspondientes obtenidos con AGNES (1.7 µmol L-1). La técnica DMT también se ha utilizado para determinar las concentraciones de Fe, Mg y Ca.
Since many years ago, heavy metals have been associated with contamination and potential toxicity. They can be found in the environment in different chemical forms, but the scientific community agrees that their toxic effects are usually dependent on the concentrations of their free form. So, proper techniques to quantify them are required. This thesis focuses on the determination of free metal concentrations in synthetic or natural samples using the analytical techniques AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Technique). In the first part of this work, a possible impact from electrodic adsorption on the electroanalytical technique AGNES has been evaluated through several systems with induced adsorption (Pb-Xylenol Orange, Cd- Polyacrilic Acid and Cd-Iodide among others). It has been confirmed that, when the special AGNES equilibrium situation at the end of the first stage is reached, the existence of other equilibria processes (such as adsorption) does not disturb the analytical signal in any of the AGNES variants. Also, for the assayed systems, the required time to reach the equilibrium state did not need to be extended. In the second part, AGNES has been applied to study the system Zn-Glutathione, first in synthetic samples and later on in root extracts of Hordeum Vulgare, considering different complexation models. In the synthetic samples determination, it has been checked that the theoretical results of two of the models agree with AGNES determinations. With the root extracts, the experimentally determined free Zn concentration was much lower than the predicted one, suggesting the presence of other ligands (such as other phytochelatins) apart from Glutathione. In the third part, the inorganic speciation in wine was studied with AGNES and with the non-electroanalytical technique DMT. Determinations of free metal ion concentrations in synthetic wine were consistent with the predicted ones, but the required time to reach equilibrium with DMT was longer. When working with real wine, it required even longer times. For free Zn concentration, DMT results, using K and Na as reference ions, (1.76 µmol L-1) agreed with the corresponding ones using AGNES (1.7 µmol L-1). The DMT technique has also be used to determine the metal concentrations of Fe, Mg and Ca.