L’analyse en ligne et in situ constitue aujourd’hui un axe de développement stratégique pour la chimie analytique. C’est particulièrement vrai dans le domaine nucléaire pour lequel les contraintes de sécurité liées à la radioactivité des échantillons, et la nécessité de limiter au maximum les déchets issus des analyses, plaident en faveur de techniques de mesure à distance, sans prélèvement ni préparation d’échantillon. La spectroscopie d’émission de plasma créé par laser (ou LIBS pour laser-induced breakdown spectroscopy), technique d’analyse élémentaire des matériaux basée sur l’ablation laser et la spectroscopie d’émission optique, possède ces qualités. C’est donc une technique de choix pour l’analyse en ligne. Cependant, la maîtrise de la mesure est délicate pour plusieurs raisons. D’abord, la LIBS est multiparamétrique et l’effet des paramètres expérimentaux sur les performances analytiques n’est pas toujours clairement établi. Ensuite, les phénomènes physiques donnant lieu au signal LIBS sont non linéaires, couplés, et transitoires. Enfin, un système d’analyse en ligne doit être le plus robuste possible face aux variations non contrôlées des conditions de mesure. L’objectif de cette thèse est donc d’améliorer la maîtrise et les performances de l’analyse quantitative par LIBS en utilisant des méthodes multivariées capables de gérer la multidimensionalité, la non linéarité et le couplage des paramètres et des données. Pour cela, le travail se décompose en deux parties. Dans un premier temps, nous avons réalisé un plan d’expériences composite centré visant à relier les paramètres expérimentaux de l’ablation laser (énergie de l’impulsion et paramètres de focalisation du faisceau) et de la détection du signal (délai après le tir laser) aux caractéristiques physiques du plasma (masse ablatée, température) et aux performances analytiques (intensité et répétabilité du signal). L’optimisation des paramètres qui en résulte est alors interprétée comme le meilleur compromis, pour l’analyse quantitative, entre efficacité d’ablation laser et chauffage du plasma. Dans un deuxième temps, nous avons développé une méthodologie multivariée basée sur les techniques MCR-ALS, ICA et PLS, pour quantifier certains éléments dans différentes matrices métalliques en exploitant, en plus de la dimension spectrale habituelle, la dimension temporelle du signal LIBS. Cette dernière, pourtant essentielle, est généralement négligée dans la littérature. Dans cette partie, nous discutons donc de l’intérêt de cette approche par rapport aux méthodes usuelles de quantification (univariée et multivariée), et de l’apport de cette méthodologie pour diagnostiquer, comprendre et éventuellement compenser les effets de matrice observés en LIBS. / Online and in situ analysis is now a strategic development for analytical chemistry. This is especially true in the nuclear field for which the security constraints related to the radioactivity of samples, and the need to minimize waste from analyzes argue for remote measurement techniques without sampling or sample preparation. Laser-Induced Breakdown Spectroscopy (LIBS) technique for elemental analysis of materials based on laser ablation and the optical emission spectroscopy, has these qualities. It is a technique of choice for online analysis. However, the processes involved in LIBS, namely laser ablation, atomization, plasma formation and emission, are quite complex and difficult to control because the underlying physical phenomena are coupled and nonlinear. In addition, the analytical performance of the LIBS technique depends strongly on the choice of experimental conditions. Finally, an online analysis system should be as robust as possible face to uncontrolled variations in measurement conditions. The processes involved in LIBS, namely laser ablation, atomization, plasma formation and emission, are quite complex and difficult to control because the underlying physical phenomena are coupled and nonlinear. In addition, the analytical performance of the LIBS technique depends strongly on the choice of experimental conditions. The objective of this thesis is to improve control and performance of quantitative analysis by LIBS using multivariate methods capable of handling multi-dimensionality, nonlinearity and the coupling between parameters and data. For this, the work is divided into two parts. First the optimization is carried out using a central composite design to model the relationship between the experimental parameters of laser ablation (pulse energy and beam focusing parameters) and signal detection (delay time) to the physical characteristics of plasma (ablated mass, temperature) and the analytical performance (intensity and repeatability of the signal). The optimization parameters that results is then interpreted as the best compromise for the quantitative analysis between efficiency of laser ablation and plasma heating. Secondly, we developed a multivariate methodology based on MCR-ALS, ICA and PLS techniques to quantify certain elements in different metallic matrices operator, in addition to the usual spectral dimension, the time dimension of LIBS signal. In this part, we discuss the value of this approach over conventional methods of quantification (univariate and multivariate) and the contribution of this methodology to diagnose, understand and possibly compensate matrix effects observed in LIBS.

Dual-comb spectroscopy (DCS) has widespread applications. It has become a more prominent spectroscopic tool because it has broad spectral coverage with high frequency resolution. We demonstrate the broadband and high resolution of DCS to probe transient events, showing the rst use of DCS of laser-induced plasmas (LIPs). Our measurements span absorption features 7 THz wide, simultaneously detecting Rb D2, K D1 and D2 absorption lines with the ability to resolve the isotope ratios in the Rb D2 line. This technique is more broadband and faster than tunable laser absorption spectroscopy because it eliminates the requirement to scan across transitions. Additionally, DCS makes higher resolution measurements than laser-induced break- down spectroscopy. Our ultimate goal is to use DCS as a technique to ascertain the chemical composition of unknown samples. Our rst demonstration of this technique illustrates that DCS makes broadband, high-resolution measurements with the ability to measure isotope ratios, which is necessary for determining sample composition.

This thesis describes experiments to investigate high-altitude relight of a lean direct injection (LDI) combustor. The features that make LDI technology less polluting in terms of NOx compared to conventional combustors are expected to impede relight performance. Therefore an improved understanding of ignition behaviour is required to ensure that stringent relight requirements can be satisfied. Realistic operating conditions are simulated in a ground-based test facility. The application of laser diagnostics presents particular difficulties due to the large quantities ofliquid fuel that impinge on the combustor walls during relight. Advances are made in the application of planar laser-induced fluorescence (PLIF) to monitor fuel placement in a combustor under these conditions. A novel apparatus is developed to deliver a laser sheet to the combustion chamber while protecting all optical surfaces from contamination. The PLIF images are compared with the cold flow field obtained from CFD modelling. These results indicate that fuel becomes trapped inside the central recirculation zone in highconcentrations. High-speed flame imaging performed simultaneously with the PLIF measurements provides important insights into the motion and breakup of flame during relight. An algorithm developed to track the flame activity reveals that the initial spark kernel is convected downstream, before breaking apart and moving upstream towards a recovery origin close to the fuel injector. Analysis of many ignition events has revealed several distinct modes of ignition failure.

MicroRNAs (miRNAs) are a class of small, single-stranded, non-protein coding RNA molecules that regulate cellular messenger RNA (mRNA) and protein levels by binding to specific mRNAs. Aberrant miRNA expression has been shown to be implicated in several diseases, including cancer. Extracellular miRNAs have been found to circulate in the bloodstream and some of their levels have been associated with different diseases. Furthermore, they hold promise as tissue- and blood-based biomarkers for cancer classification and prognostication. Blood-based biomarkers are attractive for cancer screening due to their minimal invasiveness, relatively low cost and ease of reproducibility. New miRNA analysis techniques will add toward the understanding of their biological functions. In this thesis, I investigate the utility of capillary electrophoresis (CE) and mass spectrometry (MS) for analysis of miRNAs through proof-of-concept experiments. In the fi rst part of this work, we developed a Protein-Facilitated Affinity Capillary Electrophoresis (ProFACE) assay for rapid quantification of miRNA levels in blood serum (see List of publications (6)). We also implemented a capillary electrophoresis with laser induced fluorescence detection (CE-LIF) method with online sample pre-concentration for detection of endogenous microRNAs in human serum and cancer cells. 3' modification of miRNA is a physiological and common post-transcriptional event that shows selectivity for specific miRNAs and is observed across species. Recent studies have shown that post-transcriptional addition of nucleotides to the 3' end of miRNAs is a mechanism for miRNA activity regulation. For example, such modifications in plants and C. elegans influence miRNA stability. In humans, effects on miRNA stability and on mRNA target repression have both been observed. Thus, there is a need for miRNA detection techniques which are direct and multiplexed, require minimal sample preparation and provide qualitative information regarding these modifications. We developed a multiplexed miRNA detection technique based on capillary electrophoresis coupled on line with electrospray ionization mass spectrometry (CE-ESI-MS). This method allowed a label-free, direct detection of multiple miRNAs extracted from cancer serum as well as their post-transcriptional modifications with a high mass accuracy.

Abstract: Soot from combustion emissions has a negative impact on human health and the environment. Understanding and controlling soot formation is desirable to reduce this negative impact, especially as energy demands continue to increase. In this work, a range of fundamental combustion experiments are performed to better understand the soot formation process, and to develop diagnostics for measuring soot properties. First, studies on the effects of doping the flame with different polycyclic aromatic hydrocarbons (PAHs) was performed to investigate soot nucleation mechanisms. Soot formation was found to be most sensitive to phenylacetylene addition and nucleation through physical dimerization appears to be unlikely. Next, the effects of ammonia addition, a possible future fuel, on soot formation in laminar nonpremixed ethylene counterflow flames was performed. A reduction in soot volume fraction was observed and attributed to chemical effects of ammonia addition. Second, the investigation and development of several types of diagnostics was performed. Soot is typically reported to scale with pressure as Pn where P is pressure and n is a scaling factor. A wide range of scaling factors for ethylene coflow flames have been reported using different types of diagnostics. In this work, a comparison between a light extinction technique and PLII was performed and differences between reported values was explored. Next, the time resolved laser induced incandescence (TiRe-LII) diagnostic was advanced by exploring the effects of SVF on local gas heating. Errors introduced into this model by neglecting local gas heating are explored. Finally, a new diagnostic was developed for 3 dimensional measurements of SVF and velocity in turbulent flames using a technique known as diffuse-backlight illumination extinction imaging. Third, the application of gated 2D TiRe-LII was assessed in pressurized environments on laminar coflow flames. Comparisons between TiRe-LII and thermophoretically captured soot imaged by transmission electron microscopy (TEM) was performed. TiRe-LII was found to have reasonable agreement with TEM measurements if the SNR was high, but due to the large disparity in primary particle size in pressurized environments errors in 2D TiRe-LII can be significant.

Táto diplomová práca sa zaoberá klasifikáciou kovov pomocou spektroskopie laserom indukovanej plazmy (LIBS) a chemometrických metód. Práca poskytuje prehľad o štúdiách na danú tému. Sú vybrané tri široko používané chemometrické klasifikačné metódy: "Soft Independent Modeling of Class Analogy" (SIMCA), "Partial Least Squares Discriminant Analysis" (PLS-DA) a variácia umelých neurónových sietí (ANN), "Feedforward Multilayer Perceptron". Rôzne prístupy k prieskumovej analýze su tiež preskúmané. Metódy sú stručne opísané. Následne sú klasifikátory experimentálne porovnané.

Submitted work concerns with the theoretical and practical requirements for an automatic characterization of samples by means of Laser-Induced Breakdown Spectroscopy (LIBS). Theoretical aspects of laser-matter interaction, plasma expansion, and plasma emission are described theoretically within this work. The description of the plasma emission is enhanced with the spectral detection systems and statistical properties of the plasma. The principle of the automatic characterization is based on the multivariate data analysis theoretical background, which presents recent trend and fundamental approach for automatic spectra analysis in LIBS. Theoretical knowledge is manifested in six applications, which are presented as a comment to published manuscripts. These publications push the frontiers of automatic spectra processing in LIBS.

The aim of the submitted work is a comparison of methods of quantitative analysis used in laser-induced breakdown spectroscopy (LIBS). The principles of LIBS method are explained at first, followed by a research of the most often used methods of quantitative analysis. The next part provides their description enabling a better comprehension and an eventual use of the methods in practice. Finally, the chosen methods are used to process data from the real experiment and the results are compared.

This master's thesis deals with the design and implementation of universal user interface for detection devices used in Laser-induced breakdown spectroscopy. The design and implementation are based on analysis of current state of instrumentation used in laser spectroscopy. The user interface should be able to work with high repetition frequency of measurement. Acquired spectra should be visualised to user and it is also necessary to save this data on hard drive. The resulting application must be universal. It means the application must support various types and vendors of detection devices.

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