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

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Planar Laser Induced Fluorescence (PLIF) with acetone seeding was applied to measure the scalar fields of an axisymmetric freejet and an inclined jet-in-crossflow as applicable to film cooling. From the scalar fields, jet-mixing and trajectory characteristics were obtained. In order to validate the technique, the canonical example of a nonreacting freejet of Reynolds Numbers 900-9000 was investigated. Desired structural characteristics were observed and showed strong agreement with computational modeling. After validating the technique with the axisymmetric jet, the jet-in-crossflow was tested with various velocity ratios and jet injection angles. Results indicated the degree of wall separation for different injection angles and demonstrate both the time-averaged trajectories as well as select near-wall concentration results for varying jet momentum fluxes. Consistent with literature findings, the orthogonal jet trajectory for varying blowing ratios collapsed when scaled by the jet-to-freestream velocity ratio and hole diameter, rd. Similar collapsing was demonstrated in the case of a non-orthogonal jet. Computational Fluid Dynamic (CFD) simulations using the OpenFOAM software was used to compare predictions with select experimental cases, and yielded reasonable agreement. Insight into the importance and structure of the counter rotating vortex pair and general flow field turbulence was highlighted by cross validation between CFD and experimental results.

Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are still growing analytical and sensing spectroscopic techniques. They significantly reduce the time and labor cost in analysis with simplified instrumentation, and lead to minimal or no sample damage. In this dissertation, fundamental studies to improve LIBS analytical performance were performed and its fusion with Raman into one single sensor was explored. On the fundamental side, Thomson scattering was reported for the first time to simultaneously measure the electron density and temperature of laser plasmas from a solid aluminum target at atmospheric pressure. Comparison between electron and excitation temperatures brought insights into the verification of local thermodynamic equilibrium condition in laser plasmas. To enhance LIBS emission, Microwave-Assisted LIBS (MA-LIBS) was developed and characterized. In MA-LIBS, a microwave field extends the emission lifetime of the plasma and stronger time integrated signal is obtained. Experimental results showed sensitivity improvement (more than 20-fold) and extension of the analytical range (down to a few tens of ppm) for the detection of copper traces in soil samples. Finally, laser spectroscopy systems that can perform both LIBS and Raman analysis were developed. Such systems provide two types of complimentary information – elemental composition from LIBS and structural information from Raman. Two novel approaches were reported for the first time for LIBS-Raman sensor fusion: (i) an Ultra-Violet system which combines Resonant Raman signal enhancement and high ablation efficiency from UV radiation, and (ii) a Ti:Sapphire laser based NIR system which reduces the fluorescence interference in Raman and takes advantage of femtosecond ablation for LIBS.

Laser-induced breakdown spectroscopy (LIBS) is a technique that allows quantitative and qualitative analysis of many materials. In this study, the LIBS analysis options for strontium mixture powders is expanded by increasing the number of usable strontium atomic transitions to avoid incorrect results due to spectral congestion or high strontium concentrations. The research employs double-sided tape affixed to a glass slide to hold the sample where the powder is poured onto one surface of the tape and excess dust that has not adhered is removed. This method minimizes the sample quantity needed and keeps the sample on the slide during experimentation, which also reduces costs. Herein, LIBS was used to detect and quantify the level of metal concentrations in used engine oil samples to provide valuable information about the composition of the selected material in a liquid sample. Data were obtained using multivariate analysis to develop calibration curves using LIBS spectra, which was employed for the quantification of the elements Al, Ca, Fe, Mg, and Mn. The relationship between the peak intensity of the metals in new engine oil samples and the metal concentrations in used engine oil samples were analyzed to minimize the matrix effect and the interference of element lines after which the atomic emission observed in LIBS spectra of used engine oil and new engine oil were compared. C2 molecular band emissions were also used to determine the degree of the engine oil degradation. Next, calibration models were developed for samples with high species concentrations. A partial least squares regression model was developed for calibration models to overcome matrix effect problems of some lines of each metal. This research successfully used the LIBS technique to determine the degree of engine oil degradation. This study established that used engine oil analysis using the LIBS technique can be utilized to maintain engines in good condition and to prevent engine failure. This paper presents the key findings and conclusions regarding the application of LIBS. Finally, although this technique shows many benefits and reliable results, challenges remain in terms of matrix effects, spectral pre-processing, model calibration, and instrumentation.

Single-cell bio-analytical techniques play a pivotal role in contemporary biological and biomedical research. Among current high-throughput single-cell imaging methods, coherent Raman imaging offers both high bio-compatibility and high-throughput information-rich capabilities, offering insights into cellular composition, dynamics, and function. Coherent Raman imaging finds its value in diverse applications, ranging from live cell dynamic imaging, high-throughput drug screening, fast antimicrobial susceptibility testing, etc. In this thesis, I first present a deep learning algorithm to solve the inverse problem of getting a chemically labeled image from a single-shot femtosecond stimulated Raman scattering (SRS) image. This method allows high-speed, high-throughput tracking of lipid droplet dynamics and drug response in live cells. Second, I provide image-based single-cell analysis in an engineered Escherichia coli (E. coli) population, confirming the chemical composition and subcellular structure organization of individual engineered E. coli cells. Additionally, I unveil metabolon formation in engineered E. coli by high-speed spectroscopic SRS and two-photon fluorescence imaging. Lastly, I present stimulated Raman-activated cell ejection (S-RACE) by integrating high-throughput SRS imaging, in situ image decomposition, and high-precision laser-induced cell ejection. I demonstrate the automatic imaging-identification-sorting workflow in S-RACE and advance its compatibility with versatile samples ranging from polymer particles, single live bacteria/fungus, and tissue sections. Collectively, these efforts demonstrate the valuable capability of SRS in high-throughput single-cell imaging and sorting, opening opportunities for a wide range of biological and biomedical applications.

Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much greater precision by moving either the beam or the sample. The main properties of ChG glasses investigated in this study were the light-induced and thermally-induced modification of the glass through visible microscopy, white light interferometry, and Raman spectroscopy. Additionally computational models were developed in order to aid in determining what temperature rise should be occurring under the conditions used in experiments. It was seen that ablation, photo-expansion, crystallization, and melting could occur for some of the irradiation conditions that were used. The above bandgap energy simulations appeared to overestimate the maximum temperature that should have been reached in the sample, while the below bandgap energy simulations appeared to underestimate the maximum temperature that should have been reached in the sample. Ultimately, this work produces the ground work to be able to predict and control dose, and therefore heating, to induce localized crystallization and phase change.

Laser-induced fluorescence (LIF) has been shown to be potentially useful for identifying microorganisms in real time. It is a selective and sensitive technique because the excitation is performed at one wavelength while the emission is monitored at longer wavelengths so that background from the excitation source can be eliminated. This specialized optical property of LIF can be applied to development of an optical sensor capable of quickly, non-invasively, and quantitatively probing complex biochemical transformations in microorganisms. Various bio-photonic optical fiber sensors based on laser-induced fluorescence (LIF) spectroscopy were developed as diagnostic tools for microorganisms. In the first phase, the enhancement of the sensitivity and selectivity of the optical sensor system focused on diagnosis of human breast cancer cell lines and Azotobacter vinelandii (an aerobic soil-dwelling organism). Autoluorescence spectra from human breast cancer cell lines and Azotobacter vinelandii corresponding to different growth environments were investigated. Then, the study has expanded to include the use of gold nanoparticles for specific DNA detection. The use of gold nanoparticales opens a door into construction of a compact, highly specific, inexpensive and userriendly optical fiber senor for specific DNA detection. An optical fiber laser-induced fluorescence (LIF) sensor based has been developed to detect single-strand (ss) DNA hybridization at the femtomolar level. Effects of various experimental parameters and configuration were investigated in order to optimize sensor performance and miniaturize sensor size.

<p>  </p> <p>Mass spectrometry (MS) is a powerful tool for the molecular-level characterization of complex mixtures. It is susceptible, selective, versatile, and fast. MS provides molecular weight information for the ionized analytes based on their mass-to-charge (<em>m/z</em>) ratios. Elemental compositions of the ionized analytes can be provided by MS operated at high resolution. In addition, MS provides invaluable information through tandem mass spectrometric approaches. Tandem mass spectrometry (MSn, n ≥ 2, where n is the number of ion-separation steps) utilizing collision-activated dissociation (CAD) has proven especially effective for elucidating the structures of individual compounds in complex mixtures. MS can be coupled with various external desorption/ionization methods. Laser-induced acoustic desorption (LIAD) is a technique that enables the evaporation of nonvolatile and thermally labile compounds into a mass spectrometer from the surface of the metal foil. LIAD is a soft evaporation technique that is a great companion for MS because it causes minimal fragmentation to the desorbed neutral molecules. LIAD can also be coupled with instruments other than mass spectrometers, such as molecular rotational resonance (MRR) spectrophotometer as a versatile evaporation technique. </p> <p>This dissertation focuses on research using high-resolution tandem mass spectrometric methods for the structural characterization of isomeric cations of asphaltene model compounds. The fragmentation behaviors of seven isomeric n-pentylquinoline radical cations are studied. Mechanisms for the formation of several fragment ions are also discussed based on quantum chemical calculations. Additionally, a novel suspension spin coating method is reported to improve LIAD performance. Further discussed in the dissertation is the endeavor of expanding the field of LIAD applications to MRR spectroscopy.</p>

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