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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Développements méthodologiques et logiciels pour l’imagerie X multimodale par balayage sur la ligne de lumière Nanoscopium / Methodological and software development for X-ray scanning imaging at Nanoscopium beamline

Bergamaschi, Antoine 07 March 2017 (has links)
L’objet de cette thèse est le développement méthodologique et logiciel d’outils permettant de traiter les grands volumes de données multimodales et tomographiques produits sur Nanoscopium. La technique de microscopie en rayons X durs par balayage permet l’acquisition simultanée d’information par contraste d’absorption, de phase, de diffusion et de fluorescence X. L’association des techniques de balayage avec l’infrastructure d’acquisition rapide FLYSCAN permet de proposer aux futurs utilisateurs de la ligne Nanoscopium de faire des acquisitions tomographiques multimodales. Un des principaux enjeux de cette approche est le traitement en ligne des grands volumes de données générées durant l’acquisition. Le résultat principal de cette thèse est le logiciel MMXI, dédié au traitement et à la reconstruction des jeux de données multimodales 2D et 3D. Ce logiciel intègre un algorithme dédié à la lecture de gros volumes de données, différentes fonctions de réduction de données, deux algorithmes de reconstruction de phase (intégration dans l’espace de Fourrier et technique itérative) et des algorithmes de reconstruction tomographiques (rétroprojection filtré ou itérative). L’ensemble des méthodes implémentées, des applications permettant de valider ces développements ainsi que les perspectives d’évolution sont présentées dans ce manuscrit. / The subject of this thesis is the methodological and software development of tools for processing very large multimodal and tomographic datasets produced on Nanoscopium beamline in the SOLEIL synchrotron. Scanning hard X-ray imaging allows simultaneous acquisition of multimodal information, i.e. of images in which each pixel contains several types of data. Combining these scanning techniques with the FLYSCAN infrastructure, developed for fast data acquisition at Synchrotron SOLEIL, permits to perform multimodal tomographic imaging and tomographic reconstruction during routine user experiments. A main challenge of such imaging techniques is the online processing of the important amount of generated multimodal data. The main outcome of this thesis work is the MMX-I software which is dedicated to processing large 2D/3D multimodal dataset. This software includes an original algorithm for continuous reading of large data volumes, several reduction functions, two phase reconstruction algorithms (integration in Fourier space and iterative technics) and tomographic reconstruction technics (filtered back projection and iterative technics). Every implemented method as well as application allowing to validate the new developments and few evolution perspectives are presented in this thesis manuscript.
242

Continuity and Change in Indigenous Copper Technologies of the Arctic and Central Subarctic

Matthew D Pike (9178481) 28 July 2020 (has links)
A dissertation examining technological diversity in Indigenous copper metallurgy of the North American Arctic and Central Subarctic. Variation in technological diversity is assessed cross-culturally, chronologically, and geographically. This is accomplished using diversity statistics to characterize Richness and Evenness of spatiotemporal archaeological assemblages of copper artifacts, performing regression analysis to examine the relationship to the results of a GIS Path Distance analysis that models the cost of acquisition of raw or modified copper, and performing chi-square tests of independence to compare assemblages inter-regionally and temporally. Portable X-Ray Fluorescence was utilized to discriminate geologically pure copper from smelted trade copper and a comprehensive typology of copper artifacts was created using a compiled database of known copper artifacts from across the North American Arctic and central Subarctic. Inter-regional, chronological, and cross-cultural differences in technological diversity were identified and implications for Arctic and Subarctic archaeology and technological innovation are discussed.
243

XRF för kvalitetskontroll av farmaceutiska råvaror : - metodutveckling och utbildning av användare

Danielsson, Linnea January 2012 (has links)
Detta examensarbete dokumenterar arbetet med utveckling, införande och dokumentation av en nymetod för identitetsbestämning av farmaceutiska råvaror med röntgenfluorescens. Metoden ärutvecklad för att användas på laboratorier för kvalitetskontroll på AstraZeneca i Södertälje. Syftetmed arbetet var att utveckla en robust och effektiv metod samt att utbilda användarna i dethanteringssätt som krävs för att utföra snabba och korrekta analyser. Rapporten presenterarteknologin bakom röntgenfluorescensinstrument och vilka felkällor som kan påverka resultaten samtde pedagogiska teorier som använts för att beskriva det praktiska arbete som äger rum pålaboratoriet. Metoden och de försök som föregick metoden presenteras, och resultat och beslutdiskuteras. Hur utbildningen planerades, genomfördes och utvärderades presenteras också. / This master thesis is the documented work of the development, implementation and documentationof a new method for identification of pharmaceuticals excipients using X-ray fluorescence. Themethod is supposed to be used at the laboratory for quality control at AstraZeneca, Södertälje. Thepurpose of the thesis was to develop a stout and effective method and to educate the users in theskills needed to perform fast and correct analyses. This thesis presents the technology behind XRFinstruments and which sources of errors that could affect the results as well as the pedagogicaltheories used to describe the practical work that takes place at the laboratory. The method and theexperiment that preceded the method are presented, and the results and decisions are discussed.How the education was planned, performed and evaluated is also presented.
244

XRF-mätning av tungmetaller i bottensediment under vatten

Gonzalez, Charlotte January 2021 (has links)
Syftet med denna undersökning har varit att besvara frågan om röntgenfluorescens är en bra metod för att mäta kvicksilver i bottensediment under vatten. Undersökningen har genomförts genom ett fysiskt experiment och kräver någon form av ett röntgenfluorescenssystem. Ett röntgenfluorescenssystem ger ett fluorescensspektrum som visar en intensitet av röntgenstrålar i antalet fotoner per sekund (counts) som funktion av energi i elektronvolt. Detta kan avslöja vilka grundämnen som befinner sig i fiberbanken och hur mycket av grundämnet. Röntgenfluorescens används redan i många olika applikationer, exempelvis i matindustrin, gruvor och för analys inom forskning. Denna undersökning har visat att röntgenfluorescens även fungerar för mätningar under vatten men kräver mer optimering för bättre precision.
245

Die Entdeckung der Röntgenfluoreszenzanalyse

Niese, Siegfried 09 August 2012 (has links)
Es wird die Entwicklung der Röntgenspektralanalyse und die Entdeckung der Röntgenfluoreszenzanalyse durch Georg von Hevesy und Richard Glocker mit ihren Assistenten in Freiburg i. Br. und in Stuttgart 1928 beschrieben. / The development of the x-ray chemical analysis and the discovery of the x-ray fluorescence analysis by Georg de Hevesy and Richard Glocker with their assistants in Freiburg i. Br. and in Stuttgard 1928 is described.
246

Nouvelle approche d'imagerie pour l’étude de la biodistribution de nanomédicaments / New imaging approach to the biodistribution study of innovative nanomedicine

Epaule, Céline 04 December 2017 (has links)
La distribution in vivo des médicaments est étudiée par des techniques quantitatives faiblement ou non résolues spatialement. Avec l'apparition des thérapies personnalisées, des études plus approfondies sont nécessaires pour connaître précisément le comportement des molécules vectorisées sous la forme de nanoparticules (NPs). Dans le cadre du programme européen Ternanomed, ce projet de recherche a pour objectif d’évaluer la capacité de deux techniques d’imagerie appliquées à l’étude de la distribution de nanomédicaments à base de squalène et de Cis platine (Cis-Pt). Ces deux techniques ont été sélectionnées pour leur apport d’informations complémentaires à l’échelle des organes et des tissus : i) l’imagerie par résonnance magnétique (IRM) pour suivre in vivo la biodistribution de NPs modèles à base de Cis-Pt et BiSqualène (BiSQ), marquées par des agents de contraste type oxyde de fer (USPIO), ii) l’imagerie de microfluorescence X, couplée au rayonnement synchrotron (SR-μXRF), qui ne nécessite pas de marquage préalable des nanomédicaments, pour le suivi tissulaire du Cis-Pt.Concernant l’approche par IRM, nous avons encapsulé avec succès nos USPIO synthétisées au sein des NPs de Cis-Pt BiSQ (210nm, polydispersité 0,1), tout en leur conférant un pouvoir contrastant à 7 tesla (r2=404 ms.mol-1 et r1=3 ms.mol-1). Ces NPs nouvellement préparées sont également traçables chez notre modèle murin Nudes. Les résultats de biodistribution montrent une arrivée rapide du contraste dans les organes épurateurs : le foie et la rate (5 minutes après l’injection). Au final, l’analyse par IRM a permis d’obtenir les données de biodistribution en temps réel des NPs à base de Cis Pt BiSQ, grâce au suivi du contraste apporté par les USPIO encapsulés. Concernant l’imagerie par SR-μXRF, nous avons démontré que cette technique est suffisamment sensible pour détecter et cartographier le Cis-Pt, vectorisé par nos NPs modèles. La distribution du Cis Pt a été quantifiée localement à partir d’une référence interne de concentration connue, le Zinc, à partir de notre méthode validée par le dosage globale du Platine par spectrométrie d’absorption atomique. Lorsque notre référence tissulaire n’est pas distribuée de façon homogène, une méthode semi-quantitative a été mise au point pour comparer la distribution à 2h, 8h et 24h, tel qu’au niveau des coupes de tumeurs PANC-1.Au final, ces travaux ont permis de démontrer, que la SR-μXRF et l’IRM sont des approches de choix pour l’étude pharmacocinétique et pharmacodynamique de nanomédicaments tels que les NPs à base de Cis-Pt. La technique de microfluorescence X contribue au caractère original et pionnier de ce travail de recherche, apportant des nouveaux résultats de détection et quantification important dans le domaine des nanomédecines. / Nowadays, the in vivo distribution of drugs is studied by non-spatial or partially spatial quantitative techniques. With the development of personalized therapies, many studies are required to know the in vivo behaviour of these innovative treatments, which target drugs, such as nanoparticles (NPs). Into the European funded program Ternanomed, the aim of this multidisciplinary research project was to evaluate two complementary imaging methods to study the distribution of squalene and Cis platinum (Cis Pt) NPs. The 2 imaging methods were selected to provide complementary data at the scale of organs and tissues: i) Magnetic resonance imaging (MRI) to monitor the in vivo biodistribution of NPs models based on Cis-Pt and BiSqualene (BiSQ), labelled with "UltraSmall Iron Oxide Particle" (USPIO) contrast agents, ii) X-ray microfluorescence imaging, coupled with synchrotron radiation (SR-μXRF) without any labelling of these nanomedicines, by following the Cis-Pt drug distribution into tissues.Regarding the MRI approach, we first successfully prepared Cis-Pt BiSQ NPs loading with USPIO (210nm, polydispersity 0,1). These NPs were given a contrast at 7 Tesla (r2 = 404 ms.mol-1 and r1 = 3 ms.mol-1). These newly prepared and characterized NPs were also trackable into our Nude murine model. The results show a rapid arrival of contrast in the liver and spleen scavengers (5 minutes after injection). Ultimately, MRI analysis yielded real-time biodistribution data for Cis-Pt BiSQ-based NPs by monitoring the contrast provided by encapsulated USPIO. Regarding the SR-μXRF imaging analysis, we demonstrated that this technique is very sensitive to detect and map the Cis-Pt distribution, the drug vectorized by our squalene NPs models. Additionally, a local quantitative analysis is feasible when a microelement present in the tissue is used as a reference, in our study the Zinc element. The distribution of Cis-Pt was quantified in the hepatic, renal and fat tissues, after 2h and 24h, with our method validated by the global Platinum microanalyse using atomic absorption spectrometry. When the tissue reference appears not homogenously distributed, a semi-quantitative analysis method is possible to compare the distribution such as into PANC-1 tumour sections.Finally, these two complementary approaches illustrate the use of SR-μXRF and lay the optimized bases of MRI to study the pharmacokinetics and pharmacodynamics of two new types of Cis-Pt/squalene NPs. The SR-μXRF technique, newly used in pharmaceutical field, had an effective contribution to these original and pioneering research studies with an original way of in vivo assessment of the distribution of drug embedded into nanomedicine system. The issue of detecting correct and measurable distribution of the drugs is extremely important, timely and relevant to improve current knowledge in the state of the art. This research study brings new data which can produce significant impact to the overall area of nanomedicine.
247

GEOCHEMISTRY AND PROVENANCE OF CHERT STONE TOOLS,COSHOCTON COUNTY, OHIO

Simone, Diana Marie 14 November 2019 (has links)
No description available.
248

Graphene Quantum Dots as Fluorescent and Passivation Agents for Multimodal Bioimaging / Grafen-Kvantprickar som Fluorescerande Passiveringsmedel för Multimodal Bioavbildning

Kilic, Nüzhet Inci January 2021 (has links)
Zero-dimensional graphene (carbon) quantum dots have been drawing attention in bio-related applications since their discovery, especially for their optical properties, chemical stability, and easily modifiable surface.  This thesis focuses on the green synthesis of nitrogen-doped graphene quantum dots (GQDs) for dual-mode bioimaging with X-ray fluorescence (XRF) and optical fluorescence. Both conventional and microwave- (MW-)assisted solvothermal methods were followed to investigate the precursors’ effect on the synthesized GQDs. The MW-assisted method permitted the synthesis of uniform GQDs with an excitation-independent behavior, due to highly controllable reaction conditions. It was demonstrated that the molecular structure of the precursors influenced the optical fluorescence properties of the GQDs. Thus, both blue- (BQDs) and red-emitting (RQDs) GQDs were obtained by selecting specific precursors, leading to emission maxima at 438 and 605 nm under the excitation wavelengths of 390 and 585 nm, respectively.  Amine-functionalized Rh nanoparticles (NPs) were chosen as the X-ray fluorescence (XRF) active core, synthesized via MW-assisted hydrothermal method with a custom designed sugar ligand as the reducing agent. These NPs were conjugated with BQDs using EDC-NHS treatment. The hybrid Rh-GQDs NPs exhibited green emission (520 nm) under 490 nm excitation and led to a reduced cytotoxicity with respect to bare Rh NPs, highlighting the passivation role of the GQDs via the real-time cell analysis (RTCA) assay. The hybrid complex constituted a multimodal bioimaging contrastagent, tested with confocal microscopy (in vitro) and XRF phantom experiments. / Sedan deras upptäckt har nolldimensionella kvantprickar av grafen (kol) uppmärksammats inom biorelaterade applikationer, särskilt för deras optiska egenskaper, kemiska stabilitet och enkelt modifierbara yta. Denna avhandling fokuserar på en grön syntesmetod av kvävedopade grafen-kvantprickar för bimodal bioavbildning med röntgenfluorescens och optisk fluorescens. Både konventionella och mikrovågs-assisterade solvotermiska syntesmetoder användes för att undersöka metodernas effekt på de syntetiserade kvantprickarna. Den mikrovågs-assisterade metoden möjliggjorde syntes av uniforma kvantprickar med exciteringsoberoende egenskaper på grund av mycket kontrollerbara reaktionsförhållanden. Det demonstrerades att den molekylära strukturen hos prekursorerna påverkade de optiska fluorescensegenskaperna hos grafen-kvantprickarna. Genom att välja specifika prekursorer erhölls kvantprickar som emitterar i både blått och rött ljus, motsvarande emissionsmaxima vid 438 respektive 605 nm under excitering vid 390 respektive 585 nm. Amin-funktionaliserade Rh-nanopartiklar valdes som en aktiv kärna för röntgenfluorescens, syntetiserad genom en mikrovågs-assisterad hydrotermisk metod med en specialdesignad sockerligand som reduktionsmedel. Dessa nanopartiklar konjugerades med blåemitterande kvantprickar genom EDC-NHS-behandling. De hybrida nanopartiklarna uppvisade grön emission (520 nm) under 490 nm excitation och ledde till en minskad cytotoxicitet uppmätt genom cellanalys i realtid (RTCA) jämfört med endast Rh-nanopartiklar, vilket framhävde passiveringsrollen som kvantprickarna spelar. Hybridkomplexet utgjorde ett multimodalt kontrastmedel för bioavbildning, vilket demonstrerades med konfokalmikroskopi (in vitro) och fantomexperiment med röntgenfluorescens.
249

Developing a Useful Set of Proxy Elements for the Targeting and Exploration of Gold Deposits, Black Hills, South Dakota

Harp, Michael T. 13 December 2010 (has links)
No description available.
250

Using Portable X-ray Fluorescence to Predict Physical and Chemical Properties of California Soils

Frye, Micaela D 01 August 2022 (has links) (PDF)
Soil characterization provides the basic information necessary for understanding the physical, chemical, and biological properties of soils. Knowledge about soils can in turn be used to inform management practices, optimize agricultural operations, and ensure the continuation of ecosystem services provided by soils. However, current analytical standards for identifying each distinct property are costly and time-consuming. The optimization of laboratory grade technology for wide scale use is demonstrated by advances in a proximal soil sensing technique known as portable X-ray fluorescence spectrometry (pXRF). pXRF analyzers use high energy Xrays that interact with a sample to cause characteristic reflorescence that can be distinguished by the analyzer for its energy and intensity to determine the chemical composition of the sample. While pXRF only measures total elemental abundance, the concentrations of certain elements have been used as a proxy to develop models capable of predicting soil characteristics. This study aimed to evaluate existing models and model building techniques for predicting soil pH, texture, cation exchange capacity (CEC), soil organic carbon (SOC), total nitrogen (TN), and C:N ratio from pXRF spectra and assess their fittingness for California soils by comparing predictions to results from laboratory methods. Multiple linear regression (MLR) and random forest (RF) models were created for each property using a training subset of data and evaluated by R2 , RMSE, RPD and RPIQ on an unseen test set. The California soils sample set was comprised of 480 soil samples from across the state that were subject to laboratory and pXRF analysis in GeoChem mode. Results showed that existing data models applied to the CA soils dataset lacked predictive ability. In comparison, data models generated using MLR with 10-fold cross validation for variable selection improved predictions, while algorithmic modeling produced the best estimates for all properties besides pH. The best models produced for each property gave RMSE values of 0.489 for pH, 10.8 for sand %, 6.06 for clay % (together predicting the correct texture class 74% of the time), 6.79 for CEC (cmolc/kg soil), 1.01 for SOC %, 0.062 for TN %, and 7.02 for C:N ratio. Where R2 and RMSE were observed to fluctuate inconsistently with a change in the random train/test splits, RPD and RPIQ were more stable, which may indicate a more useful representation of out of sample applicability. RF modeling for TN content provided the best predictive model overall (R2 = 0.782, RMSE = 0.062, RPD = 2.041, and RPIQ = 2.96). RF models for CEC and TN % achieved RPD values >2, indicating stable predictive models (Cheng et al., 2021). Lower RPD values between 1.75 and 2 and RPIQ >2 were also found for MLR models of CEC, and TN %, as well as RF models for SOC. Better estimates for chemical properties (CEC, N, SOC) when compared to physical properties (texture), may be attributable to a correlation between elemental signatures and organic matter. All models were improved with the addition of categorical variables (land-use and sample set) but came at a great statistical cost (9 extra predictors). Separating models by land type and lab characterization method revealed some improvements within land types, but these effects could not be fully untangled from sample set. Thus, the consortia of characterizing bodies for ‘true’ lab data may have been a drawback in model performance, by confounding inter-lab errors with predictive errors. Future studies using pXRF analysis for soil property estimation should investigate how predictive v models are affected by characterizing method and lab body. While statewide models for California soils provided what may be an acceptable level of error for some applications, models calibrated for a specific site using consistent lab characterization methods likely provide a higher degree of accuracy for indirect measurements of some key soil properties.

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