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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.
21

Prvková analýza různých druhů drobného ovoce / Elemental analysis of different kinds of small fruit

Štursa, Václav January 2014 (has links)
This diploma thesis deals with the elemental analysis of soft fruit species such as currants and gooseberries. The theoretical part contains botanical description of both species, then description of nutritional properties of the individual analyzed elements and ends with a list of analytical methods suitable for elemental analysis in the food science and with a description of preparation. The experimental part deals with sample preparation and its analysis afterwards with spectroscopic techniques. Samples of different varieties of gooseberries, black, red and white currant from “Výzkumný a šlechtitelský ústav ovocnářský v Holovousích, s.r.o.” have been used for the analysis. Samples were mineralized in concentrated HNO3 and analyzed by ICP-OES technique. Difference in resultant concentrations of the analyzed elements (Ca, Cu, Fe, K, Mg, Mn, Na, P, Zn) between individual varieties were statistically compared by Tukey’s multiple comparison method and results achieved have been as well compared with the results reported in available literature.
22

Stanovení mikro a makro prvků v balených vodách technikou ICP-OES / Determination of micro and macro elements in bottled water by ICP-OES technique

Herman, Vít January 2015 (has links)
This Master’s thesis deals with the determination of selected micro and macro elements in bottled water purchased in retail chains Czech Republic. There are described macro elements and micro elements that occur in the waters, bottled waters legislation and the most frequent used instrumental methods for elemental analysis. In this work for the analysis of bottled water were used methods optical emission spectrometry with inductively coupled plasma (ICP-OES) and ion chromatography (IC). Elemental composition of bottled water after analysis corresponded to the composition indicated on the labels, there were recorded only minor deviations from the reported concentrations. All bottled water meets the conditions of the legislation of the Czech Republic. The measured data were statistically processed in the XL Stat program and by multivariate data analysis was examined whether it is possible to individual bottled water from each other based on the analyzes differentiate, which can help in verifying the authenticity of bottled water and in the detection of adulteration of bottled water for profit.
23

Stanovení nutričních vlastností mleté papriky různého geografického původu / Determination of the nutritional properties of paprika of different geographic origin

Kovaříková, Tereza January 2017 (has links)
This master thesis deals with the analysis of nutritional properties of paprika condiment with different geographic origin. The theoretical part contains botanical description of red pepper (Capsicum annuum L.), its chemical composition, process of production of paprika and then they are described analytical methods suitable for determination of fundamental nutrional properties. Experimental part is focused on the preparation of samples and their analysis. In total, 11 samples were selected for the experiment, 5 of them had a protected designation of origin. These samples were from Slovakia, Hungary, Bulgary, Romania, Turkey and Spain. The Soxhlet extraction was used for the analysis of the fat content, Kjeldahl method was used to determine gross protein. High-performance liquid chromatography (HPLC) was chosen to determine carbohydrates and capsaicin. Induction-coupled plasma emission spectroscopy (ICP-OES) was used for elemental analysis. The results were compared with each other and with available databases and literature. For comparing and finding certain connections, the principal component analysis (PCA) was selected.
24

Focussed MeV-Ion Micro- and Nano-Beams in the Life Sciences: Selected Applications

Reinert, Tilo 15 December 2008 (has links)
This work presents the development of a sub-micron nuclear microprobe for applications in the life sciences. It includes quantitative trace element analysis with sub-micron spatial resolution, 2D- and 3D-microscopy of density distributions and the targeted irradiation of living cells with counted single ions. The analytical methods base on particle induced X-ray emission spectrometry (PIXE), Rutherford backscattering spectrometry (RBS), scanning transmission ion microscopy (STIM) and STIM-tomography. The specific development of the existing nuclear microprobe LIPSION led to an improved performance of the capabilities for trace element analysis. For sub-micron analysis the spatial resolution could be improved to 300 nm at a sensitivity of about 1 µg/g for metal ions in biological matrices; for a resolution of 1 µm the sensitivity was improved to 200 ng/g (3 µmol/l). This habilitation thesis comprises a short general introduction including the motivation to utilize focussed high energy ion beams, an overview on the applications and actual research fields. The introduction is followed by the basic principles of the equipments and analytical methods. An estimation of the limits of resolution for element analytical and single ion techniques is given for the Leipzig system. Thereafter, selected studies from different research areas are presented. The first presented application is a study from environmental air pollution research. It is demonstrated that the microscopic elemental analysis of single aerosol particles can be used to assess the contributions from different sources. A further example is the analysis of the distribution of nanoparticles in skin cross-sections for a risk assessment of the applications of nanosized physical UV-filters in cosmetic products. The risk assessment is followed by the micro-analysis of trace elements, especially of bound metal ions, in brain sections on the cellular and sub-cellular level. After this the application of focussed MeV ion beams in low dose radiobiological research is presented. Finally, the analysis of 3D-density distributions by proton micro-tomography is demonstrated. A summary concludes on the applications and gives an outlook to further applications and methodological developments. The appendix comprises the relevant publications of the author. / Die vorliegende Arbeit etabliert für Anwendungen in den Lebenswissenschaften den Einsatz hochfokussierter MeV-Ionenstrahlen für nuklear-mikroskopische Methoden der quantitativen Spurenelementanalyse, der 2D- und 3D-Dichtemikroskopie sowie für die gezielte Bestrahlung einzelner lebender Zellen für radiobiologische Experimente. Zur Anwendung kamen die Methoden ortsaufgelöste Protonen induzierte Röntgenfluoreszenzanalyse (particle induced X-ray emission - PIXE), Spektrometrie rückgestreuter Ionen (Rutherford backscattering spectrometry - RBS) und Rastertransmissionsionenmikroskopie (scanning transmission ion microscopy - STIM). Durch eine gezielte Weiterentwicklung des bestehenden Ionenstrahlmikroskops, der Hochenergie Ionennanosonde LIPSION, konnte die Ortsauflösung für Spurenelementanalyse auf unter 300 nm verbessert werden, beziehungsweise die Sensitivität für Metallionen in biologischen Proben auf unter 200 ng/g (3 µmol/l) bei einer Ortsauflösung von 1 µm verbessert werden. Die Habilitationsschrift umfasst eine kurze allgemeine Einleitung einschließlich der Motivation für den Einsatz fokussierter MeV-Ionenstrahlen sowie einen Überblick über die Anwendungsgebiete und aktuellen Forschungsschwerpunkte. Danach werden kurz die Grundlagen der Technik und Methoden vorgestellt, gefolgt von einer Abschätzung der Auflösungsgrenzen für Elementanalysen und Einzelionentechniken. Danach werden ausgewählte Anwendungen aus verschiedenen Forschungsgebieten vorgestellt. Das erstes Beispiel ist aus der Umweltforschung. Es wird dargestellt, wie mittels ortsaufgelöster Elementspektroskopie eine Abschätzung der Feinstaubbelastung nach Beiträgen einzelner Verursacherquellen erfolgen kann. Dann folgt als Beispiel eine ortsaufgelöste Analyse der Verteilung von Nanopartikeln aus Sonnencremes in Hautquerschnitten zur Risikoabschätzung der Anwendungen von Nanotechnologie in kosmetischen Produkten. Desweiteren werden Studien der Spurenelementverteilung, speziell der von gebundenen Metallionen, in Hirnschnitten auf zellulärer und subzellulärer Ebene erläutert. Das anschließende Beispiel erläutert die Anwendung niedriger Energiedosen in der Radiobiologie anhand des Beschusses einzelner lebender Zellen mit abgezählten einzelnen Ionen. Als letztes Beispiel wird die Anwendung hochfokussierter Ionenstrahlen für die Mikrotomographie gezeigt. Abschließend folgt eine zusammenfassende Bewertung der vorgestellten Anwendungen mit einem Ausblick auf weitere Anwendungen und methodische Entwicklungen. Der Arbeit sind die relevanten Veröffentlichungen mit Beteiligung des Autors als Anhang beigefügt.
25

Formulation et caractérisation de matériaux à base de liants hydrauliques utilisés dans les emballages de transport et de stockage de matières radioactives / Formulation and characterization of hydraulic binder based materials used for stockage and transport casks containing nuclear materials

Grandjean, Jérémie 28 February 2018 (has links)
ROBATEL Industries conçoit et fabrique des emballages pour matières fortement radioactives. Des matériaux de protection neutronique et thermique (PNT) sont utilisés dans ces emballages afin d’assurer la capture des neutrons et de limiter l’augmentation de la température des matières radioactives en cas d’incendie. Ces PNT sont constitués d’une matrice cimentaire ou de plâtre auxquels sont ajoutées des charges minérales ou organiques. Une charge minérale, la colemanite, permet la capture des neutrons grâce à sa teneur élevée en bore, après que l’hydrogène contenu dans les PNT les ait ralentis.Le premier enjeu de cette thèse a été de mettre au point des méthodes d’analyse élémentaire afin de caractériser l’homogénéité chimique des PNT, qui est cruciale, notamment pour le bore. Une technique de mise en solution et deux techniques de dosages ont ainsi été développées. Une autre partie importante de la thèse concerne la caractérisation des propriétés thermiques et mécaniques des PNT. D’un point de vue thermique, des mesures de chaleur de réaction, de capacité calorifique et de conductivité thermique ont été menées pour déterminer la quantité de chaleur (enthalpie) absorbée par le matériau en cas d’incendie. D’un point de vue mécanique, des essais de compression et de flexion ainsi que des essais ultrasonores ont été réalisés afin d’évaluer les valeurs des contraintes à la rupture et les modules d’élasticité des PNT. Au-delà de ces caractérisations, l’amélioration des formulations des PNT existantes et surtout la mise au point de nouvelles formulations sont au coeur de ce travail. Deux plans de mélange ont ainsi été réalisés afin d’enrichir les PNT en bore et en hydrogène tandis qu’un autre a permis l’augmentation de la fluidité d’un PNT grâce à l’ajout d’un superplastifiant. La dernière partie de la thèse a concerné l’étude de nouveaux ciments, les sulfoalumineux, qui présentent des caractéristiques intéressantes étant donné que leurs hydrates sont riches en hydrogène. Pour ces trois nouvelles familles de PNT à base de sulfoalumineux, le retard de prise induit par le bore a été limité. / ROBATEL Industries company designs and products packages for highly radioactive materials. Neutron and thermal protection materials (PNT) are used in those packages to catch neutrons and to limit the increase of temperature due to radioactive materials in case of fire. These PNT are composed of a cement or a gypsum-based matrix with mineral or organic fillers. Once the neutrons have been slowed down by the hydrogen contained in the PNT, a mineral filler named colemanite enables the neutron capture thanks to its high content of boron.The first goal of this thesis is to develop analytical chemistry techniques to check the chemical homogeneity of the PNT, which is crucial, particularly for boron. A dissolution method and two determination techniques have been developed. Another important topic in this thesis is characterization of thermal and mechanical properties. Thermal characterizations include heat of reaction, heat capacity and thermal conductivity measurements to determine the total heat absorbed by the PNT in case of fire. Mechanical characterizations include compression, bending and ultrasonic tests in order to evaluate stress to rupture and elastic moduli of PNT. Beyond the characterizations, the aim of this thesis is to improve pre-existing formulas of PNT and most importantly to propose new formulas. Two mixture designs have been carried out to increase the boron and the hydrogen concentrations of PNT. Another mixture design allowed enhancing the fluidity of a PNT using a superplasticizer. The last part of the thesis deals with the study of new cements called sulfoaluminous that show interesting properties because their hydration products are rich in hydrogen. For these three new PNT families, the increase of the setting time of cement due to boron has been restricted.
26

Elemental Analysis of Adhesive Tapes by Laser-Based Methods

Martinez Lopez, Claudia 29 October 2018 (has links)
Adhesive tapes are a common type of evidence involved in violent crimes and national security threats. This research evaluated the utility of LA-ICP-MS and LIBS for the characterization of the trace elemental signature in adhesive tapes for forensic comparisons. LA-ICP-MS and LIBS methods were developed, for the first time, for the qualitative and quantitative analysis of adhesive tapes. The backings of 90 black electrical tapes, previously characterized by conventional techniques (physical examination, IR, Py-GC-MS, and SEM-EDS), were analyzed by LA-ICP-MS to evaluate the ability of the technique to discriminate samples originating from different sources and to associate pieces of tapes originating from the same roll. The discrimination for the LA-ICP-MS analysis of the 90 samples was found to be 93.9%, greater than the discrimination found using SEM-EDS (87.3%). Moreover, 100% correct association resulted for the control samples evaluated in this study. The analysis of tapes by LIBS allowed to separate pairs of tapes that were not previously distinguished by LA-ICP-MS by detecting differences in lithium, calcium, and potassium. The potential of normalization strategies was evaluated for LIBS spectral and statistical comparisons. Two quantitative analysis methods were developed for the analysis of tapes and other polymers. These quantitative methods can help in creating and populating databases that can lead to the use of likelihood ratios and the development of standard methods of analysis and interpretation for tape evidence. Two interlaboratory trials including 7 operational and research laboratories were completed as part of this study. SEM-EDS resulted in 16.7% and 12.5% false positive rates for interlaboratory tests #1 and #2, respectively. Up to 7 and 8 elements were detected by SEM-EDS for interlaboratory test #1 and #2, respectively. LIBS and LA-ICP-MS resulted in no false positives or false negatives. In addition, increased characterization of the samples was obtained by detecting up to 17 elements by LIBS and 32 elements by LA-ICP-MS. The increased sensitivity and selectivity of LIBS and LA-ICP-MS methods has been shown to distinguish tapes originating from different sources, and to correctly associate tapes belonging to the same rolls in different laboratories and by different analysts.
27

Mechanism of laser-plasma formation in water and the application to in-situ elemental analysis / 水中レーザープラズマの生成メカニズムとその場元素分析への応用

Tamura, Ayaka 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18998号 / 工博第4040号 / 新制||工||1622(附属図書館) / 31949 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 田中 勝久 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
28

Understanding of laser ablation phenomena for quantitative elemental analysis based on underwater laser-induced breakdown spectroscopy / 水中レーザー誘起ブレークダウン分光法による定量元素分析のためのレーザーアブレーション現象の解明

Matsumoto, Ayumu 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19732号 / 工博第4187号 / 新制||工||1646(附属図書館) / 32768 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
29

Preliminary Validation Of Handheld X-ray Fluorescence (hhxrf) Spectrometry: Distinguishing Osseous And Dental Tissue From Non-bone Material Of Similar Chemical Composition

Zimmerman, Heather 01 January 2013 (has links)
Forensic anthropologists normally examine bone from a variety of medicolegal contexts. The skeletal remains may in some cases be highly fragmented or taphonomically modified, making it difficult to sort bone from non-bone material. In these cases, the forensic anthropologist may rely on microscopic or destructive chemical analyses to sort the material. However, these techniques are costly and time-intensive, prompting the use of nondestructive analytical methods in distinguishing bone and teeth from non-bone materials in a limited number of cases. The proposed analytical techniques are limited in that they rely on an examination of the major elements in the material, and do not sort out all materials with a similar chemical composition to bone/teeth. To date, no methods have been proposed for the use of handheld Xray fluorescence (HHXRF) spectrometry in discriminating human and nonhuman bone/teeth from non-bone materials. The purpose of this research was to develop a method for the use of HHXRF spectrometry in forensic anthropology specifically related to distinguishing human and nonhuman bone and teeth from non-bone materials of a similar chemical composition using multivariate statistical analyses: principal components analysis (PCA), linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and hierarchical cluster analysis (HCA). This was accomplished in two phases. Phase 1 consisted of a Reliability Test and involved sampling a single human long bone in thirty locations. Multiple spectra were collected at each location to examine the reliability of the instrument in detecting the elements both within a single site and between multiple sites. The results of the Reliability Test indicated that HHXRF consistently detected the major and minor elements found on the surface of a human bone. iv These results were used for Phase 2, designated the Accuracy Test, which involved analyzing a set of materials compiled from the literature to test the accuracy of the technique in discriminating bone (human and nonhuman) and non-bone samples (other biological and nonbiological). The results of the Accuracy Test indicate that osseous and dental tissue can be distinguished from non-bone material of similar chemical composition with a high degree of accuracy (94%) when data is collected from several locations on a sample and analyzed separately during multivariate statistical analyses. Overall, it was not possible to discriminate rock apatite and synthetic hydroxyapatite (synthetic bone) from bone. However, this technique successfully discriminated other non-bone materials that are chemically similar to bone, such as ivory and octocoral, which previous methods focusing on only a comparison of Ca/P ratios were unable to distinguish from bone.
30

Determination and Speciation of Arsenic in Environmental and Biological Samples

Berg, Tiffany 01 September 2012 (has links)
A method was developed for the determination of total arsenic in rice grain by microwave-assisted digestion inductively coupled plasma mass spectrometry. Standard calibration solutions were matrix-matched with respect to acid concentration and carbon content post-digest. The importance of eliminating the drying step during sample preparation procedures was investigated. The method was validated with spikes containing standard arsenate solutions into the rice matrix, and with certified reference material SRM1568a (rice flour) from NIST. The method was successfully applied to a commercially available rice sample. Four arsenic species [arsenate (As(V)), arsenite (As(III)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA)] were extracted from rice grains by microwave-assisted extraction and separated with high performance liquid chromatography inductively coupled plasma mass spectrometry. The method includes a novel sample clean-up step involving a dialysis procedure to decrease the amount of large starch molecules in the injection solution, in order to minimize poor resolution of chromatographic peaks and maximize column life. The method was validated with spikes of standard arsenic solutions, added to the rice matrix before the extraction procedure. Literature reference values for arsenic species quantification in SRM1568a (rice flour) were also compared. This method was successfully applied to a commercially available rice sample. A study into improvements in reverse phase-HPLC separations of arsenic species was conducted. For the first time, a Sunfire C8 column from Waters (Milford, CT) was employed for the separation of arsenic species in rice extracts. This column was compared to a Symmetry C8 column with respect to total elution time, detection limits, interference effects, and column life, and evaluated with respect to peak resolution, shifts in retention times, and peak symmetry.

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