Electrospray ionization (ESI) has become one of the most commonly used ionization techniques for mass spectrometry (MS) and ion mobility spectrometry (IMS), and efforts continue to improve its performance. ESI-MS is most recognized for its wide application to biomacromolecules where high sensitivity is of paramount importance. However, the major limitation in sensitivity with ESI-MS is due to its low ion transmission efficiency from the ESI source into the sampling orifice and through any stages utilized for transfer of ions from atmosphere to vacuum in the MS. A series of atmospheric pressure ion focusing interfaces were designed and implemented to enhance the performance of ESI-MS. The technical objective of this work was to improve sensitivity and detection limits of ESI-MS using a combination of concentric high velocity converging gas flow (aerodynamic focusing) and regulated external electric field (electrostatic focusing) to assist in focusing and transporting ions from the ESI sprayer tip into the sampling nozzle of the MS. The separation time in IMS, based on differing gas phase ion mobilities, ranges from several hundred microseconds to milliseconds. This allows faster analysis than most other conventional separation techniques, such as gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). However, the major limitation in ESI-IMS is its low resolution. It is believed that one of the most important contributions to low resolution in ESI-IMS is unwanted ion penetration through the ion gate. In order to solve this ion penetration problem, two mechanical ion gates were designed and optimized to assist in gating sprayed ions from the ESI source into the drift region of the IMS with improved sensitivity and resolution at atmospheric pressure. Applying a voltage to the ion gate and using a high flow drift gas helped to further improve the performance of ESI-IMS. Reduced pressure IMS should help to eliminate clustering and multiple peaks and, hence, improve experimental resolution when using ESI. Therefore, I report the design, construction and evaluation of new IMS systems for reduced pressures. However, the performance of the reduced pressure IMS was not as good as when using atmospheric pressure IMS.

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京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第23135号 / 薬科博第134号 / 新制||薬科||15(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 石濱 泰, 教授 松﨑 勝巳, 教授 加藤 博章 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

No / The identification of proteins involved in tumour progression or which permit enhanced or novel therapeutic targeting is essential for cancer research. Direct MALDI analysis of tissue sections is rapidly demonstrating its potential for protein imaging and profiling in the investigation of a range of disease states including cancer. MALDI-mass spectrometry imaging (MALDI-MSI) has been used here for direct visualisation and in situ characterisation of proteins in breast tumour tissue section samples. Frozen MCF7 breast tumour xenograft and human formalin-fixed paraffin-embedded breast cancer tissue sections were used. An improved protocol for on-tissue trypsin digestion is described incorporating the use of a detergent, which increases the yield of tryptic peptides for both fresh frozen and formalin-fixed paraffin-embedded tumour tissue sections. A novel approach combining MALDI-MSI and ion mobility separation MALDI-tandem mass spectrometry imaging for improving the detection of low-abundance proteins that are difficult to detect by direct MALDI-MSI analysis is described. In situ protein identification was carried out directly from the tissue section by MALDI-MSI. Numerous protein signals were detected and some proteins including histone H3, H4 and Grp75 that were abundant in the tumour region were identified

In this thesis, partial discharge (PD) phenomenon in oil-impregnated paper (OIP) is investigated under accelerated electrical stress. The thesis is mainly focused on the characteristic of PD activity and the influence it has on the insulation properties of OIP. PD source was created by introducing an air filled cavity embedded between layers of OIP. PD activity is investigated from the initiation up to final puncture breakdown of the OIP. The time-evolution of number, maximum magnitude and average magnitude of PD is investigated for cavities with different diameter and height. It was found that time to breakdown is shorter if the cavity diameter is larger and cavities with higher depth produce larger PDs. Comparison between PD activity in three cases, i.e. unaged OIP, thermally aged OIP and OIP samples with higher moisture content is performed. In general, it is found that for all cases the number and the maximum magnitude of PD follows a similar trend versus ageing time. During the very beginning of the experiment large discharges occur and they disappear after a short ageing time. Number and maximum magnitude of PD increase with time until reaching a peak value. Finally both parameters decrease with time and puncture breakdown occurs in the sample. Even though PD activity in thermally aged OIP is higher compared to the unaged OIP samples, the time to breakdown for new and thermally aged OIP samples is similar while it is shorter for OIP samples with higher moisture content. In this thesis, partial discharge (PD) phenomenon in oil-impregnated paper (OIP) is investigated under accelerated electrical stress. The thesis is mainly focused on the characteristic of PD activity and the influence it has on the insulation properties of OIP. PD source was created by introducing an air filled cavity embedded between layers of OIP. PD activity is investigated from the initiation up to final puncture breakdown of the OIP. The time-evolution of number, maximum magnitude and average magnitude of PD is investigated for cavities with different diameter and height. It was found that time to breakdown is shorter if the cavity diameter is larger and cavities with higher depth produce larger PDs. Comparison between PD activity in three cases, i.e. unaged OIP, thermally aged OIP and OIP samples with higher moisture content is performed. In general, it is found that for all cases the number and the maximum magnitude of PD follows a similar trend versus ageing time. During the very beginning of the experiment large discharges occur and they disappear after a short ageing time. Number and maximum magnitude of PD increase with time until reaching a peak value. Finally both parameters decrease with time and puncture breakdown occurs in the sample. Even though PD activity in thermally aged OIP is higher compared to the unaged OIP samples, the time to breakdown for new and thermally aged OIP samples is similar while it is shorter for OIP samples with higher moisture content. Breakdown strength of OIP samples is measured before and after ageing with PDs. It is found that the breakdown strength of OIP samples decreases by around 40% after the sample is exposed to accelerated electrical ageing. Furthermore a thermal model was developed to investigate the possible transition of breakdown mechanism from erosion to thermal breakdown in OIP dielectrics. It was found that PD activity can lower the thermal breakdown voltage of OIP up to four times. / <p>QC 20150206</p>

Traditional solution and solid state approaches (Nuclear Magnetic Resonance, X-Ray Crystallography) are methods of choice when analysing both biological and inorganic analytes. However, the characterisation of transient species, often encountered in self-assembling systems, is difficult. Such systems rarely produce crystals of high quality and due to their dynamic nature; their structures are difficult to study with NMR. Hyphenated gas phase methods which rely on mass spectrometry detection offer simultaneous structural analysis and direct stoichiometry measurement. As a consequence, it is possible to investigate specific, non-interacting molecules and molecular complexes in an isolated environment. This thesis focuses on the development and applications of two such methods - ion mobility mass spectrometry (IM-MS) and cold ion spectroscopy. IM-MS measurements yield a so called collisional cross sectional area (CCS). This parameter can be pictured as a rotationally averaged, shadow projection of a molecule structure. When correlated with the ion abundance, a CCS distribution yields intuitively interpretable information about the conformational preferences of an isolated molecule. Although indispensable in describing a "global" geometrical structure, the CCS parameter itself provides a limited insight into the local structural features of the assembly. Ion spectroscopy, both in the UV and IR regions, can provide an extra layer of highly descriptive information. Here, we present several cases where the above techniques have been applied. With the aid of IM-MS, we have analysed the geometry of inorganic supramolecular assemblies, highlighting the stability of particular metal-ligand interactions. Using cold ion spectroscopy, we have assessed the fine structural information of self-assembled oligomers of an amyloidogenic peptide. We correlated spectral features of isolated oligomers to features observed in the mature fibrils; therefore attempting to delineate the events in early stages of amyloidogenic aggregation. A major part of this report focusses on technological aspects of the design and development of a high resolution, variable temperature ion mobility mass spectrometer (VT-IM-MS). The thermal stability of molecules is a vital aspect in industrial process development and formulation science. Solution phase Differential Scanning Calorimetry (DSC) is a widely applied technique, allowing to monitor reversibility of thermally induced conformational transitions, a key aspect in protein folding analysis. The instrument reported here aims to provide parallel information about gaseous ions, with a particular focus on protein ions. Capabilities of the newly built instrument have been tested using small, rigid molecules, a small protein and a large multiprotein complex.

The yttria-stabilized zirconia (YSZ) system has been extensively studied because of its critical applications, like solid oxide fuel cells (SOFCs), oxygen sensors, and jet engines. However, there are still important questions that need to be answered and significant thermodynamic information that needs to be provided for this system. There is no predictive tool for the ionic conductivity of the cubic-YSZ (c-YSZ), as an electrolyte in SOFCs. In addition, no quantitative diagram is available regarding the oxygen ion mobility in c-YSZ, which is highly effective on its ionic conductivity. Moreover, there is no applicable phase stability diagram for the nano-YSZ, which is applied in oxygen sensors. Phase diagrams are critical tools to design new applications of materials. Furthermore, even after extensive studies on the thermodynamic database of the YSZ system, the zirconia-rich side of the system shows considerable uncertainties regarding the phase equilibria, which can make the application designs unreliable. During this dissertation, the CALPHAD (CALculation of PHase Diagrams) approach was applied to provide a predictive diagram for the ionic conductivity of the c-YSZ system. The oxygen ion mobility, activation energy, and pre-exponential factor were also predicted. In addition, the CALPHAD approach was utilized to predict the Gibbs energy of bulk YSZ at different temperatures. The surface energy of each polymorph was then added to the predicted Gibbs energy of bulk YSZ to obtain the total Gibbs energy of nano-YSZ. Therefore, a 3-D phase stability diagram for the nano-YSZ system was provided, by which the stability range of each polymorph versus temperature and particle size are presented. Re-assessment of the thermodynamic database of the YSZ system was done by applying the CALPHAD approach. All of the available thermochemical and phase equilibria data were evaluated carefully and the most reliable ones were selected for the Gibbs energy optimization process. The results calculated by the optimized thermodynamic database showed good agreement with the selected experimental data, particularly on the zirconia-rich side of the system.

The investigation and control of the properties of carbon based materials such as fullerenes and nanotubes is a highly dynamic research field. Due to its unique properties, e.g. an almost nano-dimensional size, three-dimensional cage topology, hydrophobicity, rich redox- and photochemistry, large absorption cross section, C60 has a high potential as building block for molecular devices and biological applications. It can be functionalized, anchored to a surface and self-assembled into larger supramolecular entities, such as monolayers. Mass spectrometry and related techniques such as ion-molecule reactions, action spectroscopy and ion mobility have been used throughout this work to study fullerene based systems, ranging from hydrides, derivatives, non-covalent complexes and coordinated metal complexes. Simulations predicting structural, electronic and mechanical properties have been combined with the experimental results to assist in their analysis and interpretation. Using ion molecule reactions, the reactivity of gas phase C60 anions with methanol has been studied. Hydride formation by simple collisions in the gas phase with methanol as well as reversible dehydrogenation by infrared multiphoton activation has been demonstrated. C60 functionalization by 3-azido-3-deoxythymidine (AZT) has been performed and the charged product characterized both by collisional activation and action spectroscopy. Deprotonation has been shown to lead to rearrangements of the nucleoside analogue and to a subsequent charge transfer to the fullerene. To prevent unwanted rearrangements and side reactions, encapsulation of C60 is suggested, the host molecule acting as a steric barrier. C60 complexation by γ-cyclodextrins has been performed and the ions of the complexes characterized both by collisional activation and ion mobility. It has been demonstrated that, compared to deprotonated species, the sodiated C60:(γ-cyclodextrin)2 ions were highly compact structures. With only two small polar caps accessible to reagents, sodiated C60: (γ-cyclodextrin)2 complexes sterically protect the C60 core from unwanted side reactions. Finally, explorative work on C60 immobilization on silver colloids using surface enhanced Raman spectroscopy and on the characterization of C60 complexes with iron and manganese porphyrin is presented.