Thèses sur le sujet « Layered Sample »
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ORSILLI, JACOPO. « AR-XRF Techniques for the Analysis of Cultural Heritage layered samples ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/403656.
Texte intégralIn the last decades scientific analysis has been deeply employed in the world of cultural heritage, thus, archaeologists and art historians are no more the sole front line workers of this field. Scientists, and science, have joined the team, giving new inputs and tools for the study of historical and archaeological samples, allowing to explore new paths and receive new answers, collecting information otherwise inaccessible on human history and culture. New discoveries have been made on the trade networks, migrations and on the technologies employed; besides, science also gave precious inputs on conservation and restoring procedures, allowing to better preserve fragile and sensitive artifacts. In my three years as a PhD student, I worked on the application of X-Ray Fluorescence (XRF) analysis to analyze ceramic and metal samples. XRF is a non-invasive technique that retrieves the elemental composition of a sample. In particular the aim of my PhD project is to obtain information on the layered structure of an unknown sample, distinguishing and characterizing the different layers. Indeed, artifacts usually concerning the field of Cultural Heritage present a layered structure; sometimes it is due to the presence of alteration layers, other times, instead, the objects are made of different layers from the principle, for example in the case of a glazed ceramic or of a painting. The possibility to get this information in a non-invasive way will give the possibility to analyze objects that are nowadays unattainable, because they cannot be sampled. My project has, thus, focused on the analysis of three kinds of samples employing angular dependent techniques (Angle Resolved-XRF, Grazing Emission-XRF}, Grazing Incidence-XRF}); indeed, the fluorescence signal of an analyte depends on its position inside the sample, on the sample composition and on the geometry of analysis. The chosen specimens allowed to verify the feasibility of this analytical method in an increasing complexity: a gilded laboratory-made sample, a ceramic Majolica sherd, and an Italian renaissance lustered fragment. The first two samples have been analyzed through AR-XRF where the measure is performed while tilting the sample, one spectrum is collected for each tilting angle. In the case of the gilded sample the measured profiles have been compared directly with the calculated profiles employing the Fundamental Parameters method. For the ceramic Majolica sample, instead, we studied the ratio of the profiles, as the sample surface is not flat. In the study of the metallic samples, made of gilded copper plate, we could infer the thickness of the top-layer. While in the case of the Majolica sample, we studied the different decorations, evaluating the limits of the technique, in particular in the case that the top-layer composition is similar to the underling layer, or in the case of a long-range diffusion. Instead, in the case of two well-separate layers we could retrieve information on both the composition and the thickness of the layer. Finally, the study of the lustered ceramic has been carried out at the XRF beamline of the Elettra Synchrotron of Trieste, employing grazing techniques. In this case we could only highlight and distinguish the presence of the silver nanoparticles in the luster nanolayer, which is the peculiar feature of this kind of artifacts. However, there are still many questions left, especially concerning the data analysis and the alignment of the sample, which requires more investigations.
Bilici, Cagdas. « Development of a Sediment Sampling Free Fall Penetrometer Add-on Unit for Geotechnical Characterization of Seabed Surface Layers ». Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96146.
Texte intégralPHD
Želvys, Dainius. « Ventiliuojamo oro pasiskirstymas bulvių sampile ». Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110602_120644-65726.
Texte intégralHolding potatoes in a thick 5-6 m layer in the bin it is difficult to eliminate originated hot spots. To remove the source it is necessary to intensify ventilation in order to mummify defective tubers in corruption source. The aim of the research is to investigate the patterns of ventilated air distribution in potato store and distribution of air in an experimental bench. To determine air distribution in ventilated store by changing the number of distribution ducts, and to explore opportunities to intensify ventilation arising in corruption area. It was found that reducing the number of opened distribution ducts the intensity of the ventilation in the remaining opened ducts can be doubled. At the invitation of one ducts supplied 8.34 m3/s air flow. After opening all eight ducts, each duct to be supplied only 3.9 m3/s in air. The layers next to the source will be ventilated with much smaller intensity, which decreases possibility to over ventilate production while eliminating corruption source in the store bin.
Pandozzi, Fabiano. « Spectroscopic analysis of fractal scattering and hidden layers in complex scattering samples ». Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106384.
Texte intégralLa mesure par spectroscopie optique proche infrarouge est un outil d'analyse important pour déterminer les caractéristiques d'un milieu tel la dimension des particules, l'identification de chromophore, et leur concentration. Cette information est de valeur critique pour l'évaluation d'échantillons dans les domaines pharmaceutiques, d'agriculture et environnementaux. Certains échantillons, par contre, diffusent la lumière considérablement, compliquant la mesure. Cette thèse de doctorat examine des méthodes chimiométries comprenant les règles de puissance et les analyses de composante pour extraire de l'information utile d'échantillons à partir des données, alors que l'instrumentation simplifiée est développée pour faciliter l'acquisition des données signicatives. Les techniques utilisant le temps de vol (TDV) des photons permettent de jauger les propriétés visuelles d'échantillons en utilisant la mesure temporale résolue de courtes pulsations de lumière. Il est difficile, par contre, de trouver un modèle pour les milieux à haute diffusion telles les poudres granuleuses. La configuration du profile du TDV photonique est, en grande partie, influencé par les propriétés de l'échantillon. Une analyse des règles de puissance mathématiques fut utilisée afin d'étudier les profiles du TDV, et une méthode fut développée qui pouvait, simultanément, déterminer la concentration des substances sous analyse ainsi que la grandeur des particules. Comparé aux mesures uniformes de fonctionnement traditionnelles, les estimations du coefficient d'absorption futs amélioré par 3 fois et les estimations de grandeurs ont été améliorées par 5 fois. Cette technique d'analyse s'applique à des domaines variés telle la production de produits pharmaceutiques, cosmétiques et chimiques. Quoique des méthodes existent pour étudier les propriétés optiques de substances homogènes à caractères diffusants, les substances ayant de multiples couches présentent un défi d'analyse intéressant. Les mesures faites à des points variés sur l'échantillon à multiples couches donnent de l'information sur les différentes couches présentes. Par contre, la situation se complique lorsque la couche qui doit être sondée n'est pas diffusante. Une couche ayant un facteur de réflexion atténuée, ne révèle pas d'information de la même façon qu'une couche diffusante. Une technique d'analyse fut élaborée qui a permis la séparation des composants d'absorption et diffusants pour ce genre d'échantillon à couche multiple. Des estimations précises de la concentration chromophore ont été obtenues, même lorsque la couche supérieure avait une épaisseur qui variait de 1 à 8 mm. Cette méthode a une utilité pratique dans les domaines médicaux, environnementaux et industriels.Une technique à auto-calibration inusitée fut développée pour estimer les espèces absorbantes dans une couche non diffusante incorporée dans une matrice diffusante dissemblable. Des données multispectrales à point variées, et avec lumière continue ont été obtenues d'une tête optique fantôme ayant des propriétés topographiques et optiques réalistes. Des techniques expérimentales et mathématiques futs développées qui on permit des estimations précises de la concentration chromophore. Une limite de détection correspondant à 5 µL de sang dans un volume de 150 ml de liquide céphalorachidien fut atteinte. Ce système et cette technique peuvent être utiles pour les mesures médicales non invasives, plus précisément pour la détection de saignement cérébrale.Le travail présenté dans cette thèse de doctorat explique les améliorations saillantes pour l'analyse spectroscopique d'échantillons diffusants homogènes et à couches multiples. Chaque amélioration représente une augmentation de nos connaissances de la spectroscopie. La technique à auto-calibration est particulièrement intéressante pour la communauté médicale, car elle peut être utilisée pour développer des techniques non invasives pouvant améliorer le soin de patients.
Minault, Christophe S. « Filtered vacuum arc deposition of diamond like carbon films on sharp edged samples ». Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298488.
Texte intégralLee, Kang Kug. « A Sample-to-Answer Polymer Lab-on-a-Chip with Superhydrophilic Surfaces using a Spray Layer-by-Layer Nano-Assembly Method ». University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384864905.
Texte intégralSears, S. Kelly (Stephen Kelly). « Effects of sample treatment on mixed-layer illite-smectite in X-ray diffractograms and transmission electron micrographs ». Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69658.
Texte intégralA comparison of untreated and sodium hexametaphosphate-treated ${<0.05} mu$m size fractions revealed modifications to the structure of mixed-layer I/S in both ethylene-glycol solvated and alkylammonium-ion exchanged specimens. Changes in peak position, intensity and breadths are apparent in XRD, and these modifications can also be observed in HRTEM. Lattice-fringe images revealed that pretreatment resulted in: (1) increased abundance of 2:1 layer silicate packets with expanded interlayers, (2) increased R1-ordered sequences, and (3) thinner packets of non-expanded illite interlayers. The use of sodium hexametaphosphate as a peptizer alters the interlayers and modifies the stacking arrangement of the layer structures. If the primary structure is altered, the disruption may be irreversible.
It is evident therefore, that reliable ratio determination between expandable and non-expandable components in mixed-layer I/S is dependent on characterizing all the components and resolving the effects of chemical pretreatment.
Eluru, Hima Bindu. « Deposition and Patterning of Paraffin Layers for Culture-Based Detection of Mycobacteria in Environmental Samples ». University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1093032206.
Texte intégralSirdar, Mohamed Mahmoud. « Antibiotic residues in commercial layer hens in Khartoum State, Sudan, 2007-2008 ». Diss., University of Pretoria, 2010. http://hdl.handle.net/2263/23460.
Texte intégralDissertation (MSc)--University of Pretoria, 2010.
Production Animal Studies
unrestricted
Hyndman, Rhonda Jane. « Transport studies in p-type double quantum well samples ». Thesis, University of Nottingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325711.
Texte intégralNath, Subhra K. « Spectral estimates and flow characteristics from non-uniformly sampled LDV data in a turbulent junction vortex ». Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54395.
Texte intégralPh. D.
Hörmann, Wolfgang, et Josef Leydold. « Improved Perfect Slice Sampling ». Department of Statistics and Mathematics, Abt. f. Angewandte Statistik u. Datenverarbeitung, WU Vienna University of Economics and Business, 2003. http://epub.wu.ac.at/868/1/document.pdf.
Texte intégralSeries: Preprint Series / Department of Applied Statistics and Data Processing
Woo, Hin Kyeol. « Multiscale fractality with application and statistical modeling and estimation for computer experiment of nano-particle fabrication ». Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45819.
Texte intégralHuang, Huan. « Optimizing Deposition of Matrix and Ionization Salt via Two-Step Sublimation in Sample Preparation for Surface-Layer Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Imaging (SL-MALDI-TOF MSI) ». University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619183035472425.
Texte intégralMathisen, Martin Borlaug. « In-Situ Tensile Testing Combined with EBSD Analysis of Ti-6Al-4V Samples from Components Fabricated by Additive Layer Manufacture ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18905.
Texte intégralBaccaro, Alexandre Luiz Bonizio. « Aperfeiçoamento de sistema de preparo de amostras em microescala por processamento fotoeletrocatalítico de matéria orgânica em célula eletroquímica irradiada com UV-LED, visando à análise de traços de metais ». Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-28052012-104226/.
Texte intégralThe photoelectrocatalysis process was investigated for the elimination of organic compounds interference on the electroanalysis of trace metals. Cu(II)-EDTA chelate was chosen as model system and the recovery of copper voltammetric peak, as effectiveness indicator. Thin layer cells (thickness of 600 micrometers) were designed for the treatment of some microliters of sample by irradiation (370 nm LED) of an electrode modified with TiO2 (P25, anatase rich). The following modified electrodes were prepared and evaluated: carbon paste with TiO2 and paraffin oil (CPE-TiO2), composites of graphite, TiO2 and epoxy or silicone binders and TiO2 occluded in electrodeposited gold on a gold substrate. The effect of parameters like potential bias, electrolyte composition and EDTA concentration on the photocurrent was evaluated to setup working conditions. Some correlations were observed, e.g., a linear dependence between photocurrent and EDTA concentration up to 1.0 mmol/L. For the irradiance applied, this concentration is possibly the upper limit of operation diffusion transport control, above which, the kinetics of the oxidation at the TiO2 modified electrode becomes the controlling process. For EDTA concentrations not exceeding 0.94 mmol.L-1, full recovery of 1.0 mmol.L-1 Cu(II) voltammetric peaks was observed after 10 min of irradiation. A faster procedure was discovered and consists in recording repetitive cyclic voltammograms (Au-TiO2 electrode, 0,3 to 0,7 V vs. Ag/AgCl scans, 100 mV.s-1) simultaneously with continuous irradiation. After the sixth cycle, the copper anodic stripping peak height stabilizes allowing quantification without previous sample pre-treatment step.
Gouedji, Gnamba Emmanuel. « Les séquences mafiques-ultramafiques de Samapleu et leur minéralisation en Ni-Cu-EGP : un dyke éburnéen (2,09 Ga) du complexe lité Yacouba (domaine archéen de Man - Côte d'Ivoire) ». Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2051.
Texte intégralThe Yacouba layered complex intrudes the archean (3.6-2.78 Ga) Man field in the Biankouma-Sipilou area, western Ivory Coast. In Samapleu area, the complex is composed of three entities; Samapleu Main (SM); Samapleu Extension 1 (E1) and Yorodougou (Yo). It includes websterites, peridotites, chromitites, norites, gabbro-norites horizons. These horizons (total thickness of 80 to 200 m) inclined at 70-80° to the SE; arranged symmetrically with mafic layers at the center and ultramafic layers at both margins, are features of a dyke ; show a root more than 600 m from the surface with a junction intrusion (SM, E1) in more depth.At the E1 site, contacts of intrusions with the country rock gneiss are characterized by a hybrid zone (condition P = 7.5±1Kbar and T = 850°C ± 100°C) attributed to contact metamorphism during intrusion of the complex in the lower crust at a depth of about 22 km. Zircons in country rock gneisses and granulites, as well as in the hybrid facies, yield archean ages of ~ 2.78 Ga. Rutiles in the hybrid zone give a U-Pb age of 2.09 Ga, which is interpreted as the age of contact metamorphism and emplacement of the intrusion.The Ni-Cu mineralization (disseminated mainly with subvertical and semi-massive to massive sulfide veins) is composed of pentlandite, chalcopyrite, pyrrhotite and rare pyrite. The SM and E1 sites contain Ni and Cu sulfide deposit with reserves estimated as more than 40 million tons grading 0.25% Ni and 0.22% Cu in the upper portion (Sama Nickel-CI, August 2013). The sulfide textures range from matrix ore, net-textured, droplets or breccia textures. Zones enriched in PGM, particularly Pd, are associated with the sulfides and several chromite bands are also present. These observations suggest that an immiscible sulfide liquid formed from a parental silicate liquid and percolated through the crystal pile. These sulfides mainly mantle origin were probably formed by injecting several magmas. However few of these sulfides may have formed by the assimilation of country rocks.The parental melt composition has a basalt rich MgO and low Ti and suggest Samapleu intrusions were formed by melting of the upper mantle under the influence of a mantle plume. Thus, during its ascent, magma has assimilated the granulites country rocks
Söderström, Hanna. « Semipermeable membrane devices as integrative tools for monitoring nonpolar aromatic compounds in air ». Doctoral thesis, Umeå University, Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-378.
Texte intégralAir pollutants pose a high risk for humans, and the environment, and this pollution is one of the major environmental problems facing modern society. Active air sampling is the technique that has been traditionally used to monitor nonpolar aromatic air pollutants. However, active high volume samplers (HiVols) require a power supply, maintenance and specialist operators, and the equipment is often expensive. Thus, there is a need to develop new, less complicated sampling techniques that can increase the monitoring frequency, the geographical distribution of the measurements, and the number of sites used in air monitoring programs. In the work underlying this thesis, the use of semipermeable membrane devices (SPMDs) as tools for monitoring gas phase concentrations of nonpolar aromatic compound was evaluated using the compound classes polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (alkyl-PAHs) and nitrated PAHs (nitro-PAHs) as test compounds.
High wind-speeds increased the uptake and release in SPMDs of PAHs and PCBs with log KOA values > 7.9, demonstrating that the uptake of most nonpolar aromatic compounds is controlled by the boundary layer at the membrane-air interface. The use of a metal umbrella to shelter the SPMDs decreased the uptake of PAHs and PCBs by 38 and 55 percent, respectively, at high wind/turbulence, and thus reduced the wind effect. Further, the use of performance reference compounds (PRCs) to assess the site effect of wind on the uptake in SPMDs reduced the between-site differences to less than 50 percent from as much as three times differences in uptake of PCBs and PAHs. However, analytical interferences reduced the precision of some PRCs, showing the importance of using robust analytical quality control.
SPMDs were shown to be efficient samplers of gas phase nonpolar aromatic compounds, and were able to determine local, continental and indoor spatial distributions of PAHs, alkyl- PAHs and nitro-PAHs. In addition, the use of the SPMDs, which do not require electricity, made sampling possible at remote/rural areas where the infrastructure was limited. SPMDs were also used to determine the source of PAH pollution, and different approaches were discussed. Finally, SPMDs were used to estimate the importance of the gas phase exposure route to the uptake of PAHs in plants. The results demonstrate that SPMDs have several advantages compared with HiVols, including integrative capacity over long times, reduced costs, and no need of special operators, maintenance or power supply for sampling. However, calibration data of SPMDs in air are limited, and spatial differences are often only semi-quantitatively determined by comparing amounts and profiles in the SPMDs, which have limited their use in air monitoring programs. In future work, it is therefore important that SPMDs are properly sheltered, PRCs are used in the sampling protocols, and that calibrated sampling rate data, or the SPMD-air partition data, of specific compounds are further developed to make determination of time weighted average (TWA) concentrations possible.
Subercaze, Alexandre. « Utilisation combinée des rayons X et gamma émis lors de l'interaction avec la matière d'ions légers aux énergies intermédiaires : des mécanismes primaires de réaction aux applications ». Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0053/document.
Texte intégralParticle Induced X-ray Emission (PIXE) and Particle Induced Gamma-ray Emission (PIGE) are multi-elemental and non-destructives techniques. They are based on the detection of characteristic X-ray and gamma emission induced by the interaction of accelerated charged particles with matter. Elements with an atomic number Z> 11 can be quantified reaching a limit of detection in the order of μg/g (ppm). X-rays from light elements are strongly attenuate by matter. Therefore, PIXE shows little sensitivity for lights elements. Those elements are analyzed simultaneously using PIGE. One of the benefits of PIXE/PIGE is its ability to perform analysis with different requirement (elemental concentration mapping, in-depth analysis, valuable objects). Homogeneous and non-homogenous samples can be studied thanks to PIXE/PIGE. High energy PIXE (HEPIXE) has been developed at the ARRONAX cyclotron using particles beams up to 70 MeV. Thus analysis of thick samples is achievable using HEPIXE. Using high energy beams can also reduce the risk of damaging the sample. First of all, the high energy PIXE/PIGE platform develop at ARRONAX is described. Then the results given by high energy PIGE analysis and the experimental procedure for gamma emission cross section measurements are discussed. Finally, the methods developed and the results obtained during the analysis of inhomogeneous samples (multi-layer and granular samples) are presented and discussed
Skoupý, Radim. « Quantitative Imaging in Scanning Electron Microscope ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-432610.
Texte intégralDelignat-Lavaud, Antoine. « On the security of authentication protocols on the web ». Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEE018/document.
Texte intégralAs ever more private user data gets stored on the Web, ensuring proper protection of this data (in particular when it transits through untrusted networks, or when it is accessed by the user from her browser) becomes increasingly critical. However, in order to formally prove that, for instance, email from GMail can only be accessed by knowing the user’s password, assuming some reasonable set of assumptions about what an attacker cannot do (e.g. he cannot break AES encryption), one must precisely understand the security properties of many complex protocols and standards (including DNS, TLS, X.509, HTTP, HTML,JavaScript), and more importantly, the composite security goals of the complete Web stack.In addition to this compositional security challenge, onemust account for the powerful additional attacker capabilities that are specific to the Web, besides the usual tampering of network messages. For instance, a user may browse a malicious pages while keeping an active GMail session in a tab; this page is allowed to trigger arbitrary, implicitly authenticated requests to GMail using JavaScript (even though the isolation policy of the browser may prevent it from reading the response). An attacker may also inject himself into honest page (for instance, as a malicious advertising script, or exploiting a data sanitization flaw), get the user to click bad links, or try to impersonate other pages.Besides the attacker, the protocols and applications are themselves a lot more complex than typical examples from the protocol analysis literature. Logging into GMail already requires multiple TLS sessions and HTTP requests between (at least) three principals, representing dozens of atomic messages. Hence, ad hoc models and hand written proofs do not scale to the complexity of Web protocols, mandating the use of advanced verification automation and modeling tools.Lastly, even assuming that the design of GMail is indeed secure against such an attacker, any single programming bug may completely undermine the security of the whole system. Therefore, in addition to modeling protocols based on their specification, it is necessary to evaluate implementations in order to achieve practical security.The goal of this thesis is to develop new tools and methods that can serve as the foundation towards an extensive compositional Web security analysis framework that could be used to implement and formally verify applications against a reasonably extensive model of attacker capabilities on the Web. To this end, we investigate the design of Web protocols at various levels (TLS, HTTP, HTML, JavaScript) and evaluate their composition using a broad range of formal methods, including symbolic protocol models, type systems, model extraction, and type-based program verification. We also analyze current implementations and develop some new verified versions to run tests against. We uncover a broad range of vulnerabilities in protocols and their implementations, and propose countermeasures that we formally verify, some of which have been implemented in browsers and by various websites. For instance, the Triple Handshake attack we discovered required a protocol fix (RFC 7627), and influenced the design of the new version 1.3 of the TLS protocol
Pal, Terek. « Unapređenje kvaliteta alata za livenje pod pritiskom primenom tehnologija inženjerstva površina ». Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=101472&source=NDLTD&language=en.
Texte intégralCorrosion resistance and soldering tendency of different materials in moltenAl–Si–Cu alloy were studied. Hot-working tool steel, plasma nitrided steel andduplex layers with CrN, TiAlN, TiAlSiN and CrAlN top coatings, which wereproduced to various degree of surface roughness, were covered by the study.An ejection test was employed for investigation of the concerned phenomena.The ejection test was improved in order to increase its accuracy and thereliability of process simulation. Samples were examined in both short andextended periods of contact (5 and 20 min) with liquid casting. Castingsolidification was extended in order to intensify the corrosion effects. Contraryto common findings, it was found that the ejection force of the investigatedmaterials does not depend on their chemical composition. For the coatedsamples, a pronounced dependence of the ejection force on the surfaceroughness was found. The ejection force increases with decrease in surfaceroughness. All investigated coatings are prone to mechanical soldering by Al–Si–Cu alloy. Still, their corrosion resistance substantially exceeds the corrosionresistance of steel and plasma nitrided layer. Longer exposure of coatedsamples to cast alloy induced lower ejection forces, which is a consequenceof coatings oxidation. It was found that the investigated coatings are inert toliquid aluminium. However, the underlying material undergoes oxidation andcorrosion through coating growth defects. The findings concerning the wearmechanisms of protective layers support further development of duplex layersintended for die casting tools protection.
Kosmata, Marcel. « Elastische Rückstoßatomspektrometrie leichter Elemente mit Subnanometer-Tiefenauflösung ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-84041.
Texte intégralIn this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two compo-nents. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a high-resistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during heavy ion irradiation. It is shown that the used energies occur both electronic sputtering and electronically induced interface mixing. Electronic sputtering is minimised by using optimised beam parameters. For most samples the effect is below the detection limit for a fluence sufficient for the analysis. However, the influence of interface mixing is so strong that it has to be included in the analysis of the layers of the depth profiles. It is concluded from these studies that at the Rossendorf 5 MV tandem accelerator chlorine ions with an energy of 20 MeV deliver the best results. In some cases, such as the analysis of boron, the energy must be reduced to 6.5 MeV in order to retain the electronic sputtering below the detection limit. The fourth focus is the study of the influence of specific sample properties, such as surface roughness, on the shape of a measured energy spectra and respectively on the analysed depth profile. It is shown that knowledge of the roughness of a sample at the surface and at the interfaces for the analysis is needed. In addition, the contribution parameters limiting the depth resolution are calculated and compared with the conventional ion beam analysis. Finally, a comparison is made between the high-resolution ion beam analysis and complementary methods published by other research groups. The fifth and last focus is the analysis of light elements in ultra thin layers. All models presented in this thesis to reduce the influence of beam damage are taken into account. The dynamic non-equilibrium charge state is also included for the quantification of elements. Depth profiling of multilayer systems is demonstrated for systems consisting of SiO2-Si3N4Ox-SiO2 on silicon, boron implantation profiles for ultra shallow junctions and ultra thin oxide layers, such as used as high-k materials
Assunção, Marisa Sofia de Oliveira. « High-performance thin-layer chromatography detection of globotriaosylceramide in urine samples : improvement of the method and sampling ». Master's thesis, 2012. http://hdl.handle.net/1822/23027.
Texte intégralFabry disease (FD) is a lysosomal storage disorder caused by deficient or null production of the enzyme α-galactosidase A (α-Gal A) as a result of mutations in α-galactosidase A gene (GLA), located on the X chromosome. The systemic accumulation of α-Gal A substrates, which are excreted in urine, leads to progressive damage of several organs and tissues and ultimately results in death due to heart failure, renal failure and cerebrovascular accidents. Many studies are focused in diagnosing FD through measurement of α-Gal A activity in blood and of accumulated substrates, mainly globotriaosylceramide, in plasma or urine. Mass spectrometry techniques are extensively used for screening of FD and other lysosomal storage disorders. However, mass spectrometry is an expensive method, requires a specialized operator and involves complex equipment. Thin-layer chromatography, on the other hand, is a robust and well explored method suitable for analysis of a large number of samples. The collection of urine samples is easy and non-invasive, which facilitates the cooperation of the subjects, but urine samples are difficult to transport without degradation. In this study, the problematic of urine samples transport was overcome by using filter paper as a supporting material that allows shipping through general mail without deterioration. The high-performance thin-layer chromatography method conventionally used to analyse Gb3 in urine samples was successfully optimised to analyse urine in filter paper. Using this method 60% of the previously diagnosed FD patients revealed increased Gb3 levels and one patient on enzyme replacement therapy showed significant Gb3 reduction after three months of therapy. The developed screening method offers an easy and simple method for urine sample shipping without degradation and suitable for a mass screening and ERT follow up program.
A doença de Fabry (FD) é uma doença lisossomal de sobrecarga causada pela atividade deficiente da enzima α-galactosidase A (α-Gal A) do, como resultado de mutações no gene desta enzima (gene GLA), localizado no cromossoma X. A acumulação sistémica dos substratos da α-Gal A, que são excretados na urina, leva à lesão progressiva de vários órgãos e tecidos, conduzindo por fim à morte devido a falência cardíaca, falência renal e acidentes vasculares cerebrais. Vários estudos estão debruçados no diagnóstico da doença de Fabry através da medição da atividade da α-Gal A em sangue e de substratos acumulados, principalmente o globotriaosilceramida, em urina e plasma. As técnicas de espectrometria de massa são extensivamente no rastreio da doença de Fabry e outras doenças lisossomais de sobrecarga. Contudo, a espectrometria de massa é um método dispendioso, requer um operador especializado e envolve equipamentos complexos. A cromatografia em camada fina, por sua vez, é um método robusto e bem explorado adequado à análise de grandes grupos de amostras. A colheita de amostras de urina é fácil e não é invasiva, o que facilita a cooperação por parte dos dadores, mas as amostras de urina são difíceis de transportar sem que haja deterioração. Neste estudo, a problemática do transporte de amostras de urina foi ultrapassada utilizando o papel de filtro como material de suporte, permitindo que as amostras sejam enviadas por correio normal sem degradação. O método de cromatografia em camada fina de alta performance convencionalmente utilizado na análise de Gb3, em amostras de urina, foi otimizado com sucesso para analisar amostras de urina em papel de filtro. Recorrendo a esta metodologia, verificou-se que os níveis de Gb3 estavam aumentados em 60% dos doentes de Fabry previamente diagnosticados, e que um paciente em terapia enzimática de substituição mostrou uma redução significativa de Gb3 após três meses de terapia. O método de rastreio desenvolvido oferece um modo simples e fácil de envio das amostras de urina sem que haja degradação, sendo por isso, adequado para o rastreio em massa e seguimento dos pacientes em terapia.
Fundação para a Ciência e a Tecnologia (FCT) - Projeto PTDC/SAL‐BEB/100875/2008 “Fabry Screen – Screening for Fabry disease based on automatic classification of chromatographic images”
Suarez, Kaitlyn. « In-situ Zircon and Monazite Geochronology from Compositionally Distinct Layers in a Single Migmatitic Paragneiss Sample Located in the Eastern Adirondack Mountains, NY ». 2019. https://scholarworks.umass.edu/masters_theses_2/799.
Texte intégralRogalsky, Christine Jane. « Application of a Network Model for Complex Fenestration Systems ». Thesis, 2011. http://hdl.handle.net/10012/6211.
Texte intégralLu, Guan-Huei, et 呂冠慧. « Preparation of layer double hydroxide as sorbent for headspace solid-phase microextraction of halophenols in environmental samples for GC-ECD analysis ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4j4fw2.
Texte intégral國立中興大學
化學系所
107
A layered double hydroxide (LDH) material was prepared and coated onto the surface of glassy fiber as a sorbent of solid phase microextraction (SPME) to collect halo-phenols in aqueous samples by headspace sampling for GC-ECD analysis. The LDH material was prepared by mixing magnesium nitrate and aluminum nitrate in water homogeneously and adjusted the pH to 10, then reflux for 24 hrs at 100 oC. After washing with water to neutral and then by alcohol, the LDH was formed posterior to dry in an oven. The SPME-LDH sorbent was prepared by dip-coating a glassy fiber into a mixed solution of LDH and silicone adhesive several times and dried vertically. The effectiveness of LDH fiber preparation was identified their functional groups by FT-IR, and the surface was observed with SEM. A headspace sampling of halo-phenols from 10 mL aqueous sample in a 20 mL sampling-vial was examined. Factors affecting the sampling such as the pH and temperature of sample, stir-rate, salting-out effect, and extraction time were optimized. Results indicated that the sampling was optimal at pH 2.0, 30% NaCl addition, 1000 rpm stirring at 60 oC for 35 min. For desorption and analysis by GC-ECD, detections are linear in 0.05 - 7.5, 0.01 - 1.5, and 0.005 - 7.5 μgL-1 for trichlorophenol, tetrachlorophenol, tribromophenol and pentachlorophenol, respectively, with correlation coefficients (R2) in 0.9960 - 0.9978. Detection limits are in 1.3 - 14.6 ngL-1 and method detection limits are in 4.4 - 48.5 ngL-1. The method was used to analyze four halophenols in river water and in farm-soil samples, and no residuals of halophenols was found. When spiked standards in samples and analyzed by the method, the recoveries of halophenols were in 86.6 - 98.3% with RSD in 2.4 - 7.4 %, and in 86.6 - 98.5 % with RSD in 2.8 - 7.7 %, respectively. The prepared LDH absorbent for SPME sampling with advantages of easy preparation, thermal stability, low-costs, high-enrichment, no carry-over, and no organic solvent required. Thus, it is a simple, rapid, sensitive, inexpensive, and eco-friendly sample preparation method.
Akkad, Rami [Verfasser]. « Determination of organophosphorus and carbamate insecticides in food samples by high-performance thin-layer chromatography multi-enzyme inhibition assay / vorgelegt von Rami Akkad ». 2011. http://d-nb.info/1011981904/34.
Texte intégralChen, Yu-yu, et 陳佑瑜. « Investigations of the Anisotropic Property of Nonpolar a-plane GaN,(11-22) Semipolar InGaN/GaN Multiple Quantum Wells and the Effects of Growth Time of Low-Temperature Buffer Layer on the Sample Quality of N-polar GaN ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/89652905252422884918.
Texte intégral國立高雄大學
應用物理學系碩士班
99
This thesis studies the anisotropic properties of N-polar GaN, nonpolar a-plane GaN, and (11-22) semipolar InGaN/GaN MQW samples grown by MOVCD. The optical and material properties were investigated by photoluminescence (PL), and time-resolved PL measurements, atomic force microscopy (AFM), field-emission electron microscopy (FE-SEM), and cathodoluminescence (CL). First, for N-polar GaN samples, we study the effects of the buffer layer growth times on the material and optical properties of three N-polar GaN samples with different growth times (114, 120, and 180 seconds) of low temperature (LT) buffer layer. As the growth time of the low temperature buffer increases, the PL and CL intensities decrease, due to a rougher surface morphology. Also, the stress is associated with PL peak position by Raman scattering. Second, we study nonpolar a-plane GaN on r-sapphire with the different thickness first-step a-GaN. For nonpolar a-plane GaN samples, the main peak (~365 nm) in the CL spectrum is associated with the partial dislocation terminating basal stacking faults (BSFs) and two main peaks around ~355 nm and ~363 nm in PL the spectrum are attributed to near-band-edge (NBE) emission and BSFs, respectively. Third, for (11-22) semipolar InGaN/GaN MQW samples, the main peak around ~403 nm is the InGaN-related emission, while the other weak peaks are the GaN-related emission in the PL Spectrum. As the sample has the stronger CL luminescence, the striation feature with a rougher surface morphology can be observed.
Kosmata, Marcel. « Elastische Rückstoßatomspektrometrie leichter Elemente mit Subnanometer-Tiefenauflösung ». Doctoral thesis, 2011. https://tud.qucosa.de/id/qucosa%3A25920.
Texte intégralIn this thesis the QQDS magnetic spectrometer that is used for high resolution ion beam analysis (IBA) of light elements at the Helmholtz-Zentrum Dresden-Rossendorf is presented for the first time. In addition all parameters are investigated that influence the analysis. Methods and models are presented with which the effects can be minimised or calculated. There are five focal points of this thesis. The first point is the construction and commissioning of the QQDS magnetic spectrometer, the corresponding scattering chamber with all the peripherals and the detector, which is specially developed for high resolution elastic recoil detection. Both the reconstructed spectrometer and the detector were adapted to the specific experimental conditions needed for high-resolution Ion beam analysis of light elements and tested for routine practice. The detector consists of two compo-nents. At the back end of the detector a Bragg ionization chamber is mounted, which is used for the particle identification. At the front end, directly behind the entrance window a proportional counter is mounted. This proportional counter includes a high-resistance anode. Thus, the position of the particles is determined in the detector. The following two points concern fundamental studies of ion-solid interaction. By using a magnetic spectrometer the charge state distribution of the particles scattered from the sample after a binary collision is both possible and necessary for the analysis. For this reason the charge states are measured and compared with existing models. In addition, a model is developed that takes into account the charge state dependent energy loss. It is shown that without the application of this model the depth profiles do not correspond with the quantitative measurements by conventional IBA methods and with the thickness obtained by transmission electron microscopy. The second fundamental ion-solid interaction is the damage and the modification of the sample that occurs during heavy ion irradiation. It is shown that the used energies occur both electronic sputtering and electronically induced interface mixing. Electronic sputtering is minimised by using optimised beam parameters. For most samples the effect is below the detection limit for a fluence sufficient for the analysis. However, the influence of interface mixing is so strong that it has to be included in the analysis of the layers of the depth profiles. It is concluded from these studies that at the Rossendorf 5 MV tandem accelerator chlorine ions with an energy of 20 MeV deliver the best results. In some cases, such as the analysis of boron, the energy must be reduced to 6.5 MeV in order to retain the electronic sputtering below the detection limit. The fourth focus is the study of the influence of specific sample properties, such as surface roughness, on the shape of a measured energy spectra and respectively on the analysed depth profile. It is shown that knowledge of the roughness of a sample at the surface and at the interfaces for the analysis is needed. In addition, the contribution parameters limiting the depth resolution are calculated and compared with the conventional ion beam analysis. Finally, a comparison is made between the high-resolution ion beam analysis and complementary methods published by other research groups. The fifth and last focus is the analysis of light elements in ultra thin layers. All models presented in this thesis to reduce the influence of beam damage are taken into account. The dynamic non-equilibrium charge state is also included for the quantification of elements. Depth profiling of multilayer systems is demonstrated for systems consisting of SiO2-Si3N4Ox-SiO2 on silicon, boron implantation profiles for ultra shallow junctions and ultra thin oxide layers, such as used as high-k materials.