Dissertations / Theses: 'Ion imaging'

1

Rogers, Leon John. "Photofragment ion imaging." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266958.

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Yuen, Wei Hao. "Ion imaging mass spectrometry." Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564395.

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This work investigates the applicability of fast detectors to the technique of microscope-mode imaging mass spectrometry. By ionising analyte from a large area of the sample, and projecting the desorbed ions by the use of ion optics through a time-of-flight mass spectrometer onto a two- dimensional detector, time- (and hence mass-) dependent distributions of ions may be imaged. To date, this method of imaging mass spectrometry has been limited by the ability to image only one mass window of interest per experimental cycle, limiting throughput and processing speed. Thus, the alternative microprobe-mode imaging mass spectrometry is currently the dominant method of analysis, with its superior mass resolution. The application of fast detectors to microscope-mode imaging lifts the restriction of the detection of a single mass window per experimental cycle, potentially decreasing acquisition time by a factor of the number of mass peaks of interest. Additional advantages include the reduction of sample damage by laser ablation, and the potential identification of coincident eo-fragments of different masses originating from the same parent molecule. Theoretical calculations and simulations have been performed confirming the suitability of conventional time-of-flight velocity-mapped ion imaging apparatus for imaging mass spectrometry. Only small modifications to the repeller plate and laser beam path, together with the adjustment of the accelerating potential field, were required to convert the apparatus to a wide (7 mm diameter) field-of-view ion microscope. Factors affecting the mass and spatial resolution were investigated with these theoretical calculations, with theoretical calculations predicting a spatial resolution of about 26μm and m/m of 93. Typical experimental data collected from velocity-mapped ion imaging experiments were collected, and characterised in order to provide specifications for a novel time-stamping detector, the Pixel Imaging Mass Spectrometry detector. From these data, the suitability of thresholding and centroiding on the new detector was determined. Initial experiments using desorptionjionisation on silicon and conventional charge-coupled device cameras confirmed the correct spatial-mapping of the apparatus. Matrix-assisted laser desorptionjionisation techniques (MALDI) were used in experiments to determine the spatial and mass resolutions attainable with the apparatus. Experimental spatial resolutions of 14.4 μm and m/m of 60 were found. The better experimental spatial resolution indicates a higher di- rectionality of initial velocities from MALDI desorption than used in the theoretical predictions, while the poorer mass resolution could be attributed to limitations imposed by the use of the phosphor screen. Proof-of-concept experiments using fast-framing cameras and the new time-stamping detectors confirmed the feasibility of multiple mass acquisition in time-of-flight microscope mode ion imaging. Mass-dependent distributions were acquired of different pigment distributions in each experimental cycle. Finally, spatial-mapped images of coronal mouse brain sections were acquired using both conventional and fast detectors. The apparatus was demonstrated to provide accurate spatial distributions with a wide field-of-view, and multiple mass distributions were acquired with each experimental cycle using the new time-stamping detector.

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Johnsen, Alexander. "Ion Imaging, applications and extensions." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533852.

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4

Beckert, Marco. "Photodissociation dynamics of halogens and halogen-ions studied by ion imaging." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274674.

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5

King, Philip J. C. "Crystal defect imaging using transmission ion channelling." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358679.

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Rivas, Charlotte. "Dual-modal imaging agents for zinc ion sensing." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/30814.

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The area of MRI/optical imaging has received a lot of attention as their combination brings together the high spatial resolution of MRI with the high sensitivity of optical imaging. Changes in pancreatic β-cell mass contribute to the development of both type 1 and type 2 diabetes. Whilst the processes of β-cell loss are fairly well established for type 1, both the extent of the loss and the underlying mechanisms are relatively unknown for type 2. Zinc ions are highly concentrated in the insulin granules that are contained within β-cells. Few robust approaches currently exist to monitor changes in β-cell mass in vivo, and as such, this project aims to develop responsive lanthanide complexes to bind selectively and respond to zinc levels in this target area. The introductory chapter considers the fundamental aspects of molecular imaging, with a particular focus on magnetic resonance and optical imaging, as well as the intrinsic properties of the lanthanide elements, such as magnetism and luminescence. The subsequent results chapters contain more detailed introductions, relevant to the topics covered within the chapter. The synthesis of dual-modal MR/optical probes is described in chapter two. Three rhodamine-based [GdDO3A] complexes are described and their relaxivity and fluorescence properties are established. The Eu3+ and Tb3+ analogues are also studied. Two of the complexes, which show superior water solubilities, are further studied in in vitro and in vivo experiments. One probe displays a fluorescence pH sensitivity that allows for the differentiation of healthy cells from malignant cells due to their difference in pH whilst the other probe displays fluorescence at all pH's. Both probes show accumulation in the mitochondria. Chapter three discusses the synthesis of an MR zinc sensor using a BPEN chelator as the zinc-binding moiety. Showing high selectivity for zinc, this probe is then further functionalised with the rhodamine fluorophore derivative previously described to give a dual- modal MR/fluorescent zinc sensor. This probe only shows an MR response in the presence of zinc. In vitro experiments show the localisation of the probe to differ from the results of the dual-modal probes discussed in chapter two, showing cytosol localisation. Finally, chapter four concerns the synthesis of a fluorescent zinc sensor and its conjugation to a [GdDO3A] scaffold to give a dual-modal MR/optical zinc sensor. This probe displays an improved response to zinc showing increases in both relaxivity and fluorescence. In vitro experiments with both INS1 and HEK cells show the probe to localise in the lysosome and mitochondria respectively.

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Nakata, Yoshihiko. "Imaging Mass Spectrometry with MeV Heavy Ion Beams." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/124537.

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Kogovsek, Laurie Maylish. "Magnetic resonance imaging of elastomers and ion exchange resins." Case Western Reserve University School of Graduate Studies / OhioLINK, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1057869238.

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Monti, Oliver A. L. "Crossing thresholds : Rydberg-tagging and near-threshold photodissociation." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365747.

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Cooper, Martin James. "Spectroscopy and photodissociation dynamics of diatomic molecules." Thesis, University of Bristol, 1998. http://hdl.handle.net/1983/b6fb7599-b7a3-4e6d-9945-7b59e6204496.

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Blums, Valdis Roberts. "Ion Fluorescence Collection And Diffraction Limited Imaging From A Microfabricated Ion Trap With Integrated Diffractive Mirrors." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365461.

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In this thesis I discuss the collaborative monolithic design and testing of microfabricated diffractive mirrors integrated into a microfabricated ion trap. I discuss the necessary optical and electrical systems needed to trap 174Yb+ ions. From the diffractive mirrors we measured a collection efficiency of more than 4% per ion fluorescence photon, while obtaining diffraction limited ion images.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Natural Sciences
Science, Environment, Engineering and Technology
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Freeman, Stewart Peter Hans Thielbeer. "The radiocarbon microprobe : an imaging secondary ion accelerator mass spectrometer." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314932.

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Panday, Namuna. "Scanning Ion Conductance Microscopy for Single Cell Imaging and Analysis." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3477.

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Most biological experiments are performed on an ensemble of cells under the assumption that all cells are identical. However, recent evidence from single cells studies reveals that this assumption is incorrect. Individual cells within the same generation may differ dramatically, and these differences have important consequences for the health and function of the entire living body. I have used Scanning Ion Conductance Microscopy (SICM) for imaging and analysis of topographical change of single cell membrane, which is difficult to be revealed by optical microscopes. Morphological change in the fixed and live HeLa cell membrane during endocytosis of conjugated polymer nanoparticles was studied. Results demonstrated SICM is a powerful tool to study the interaction between nanoparticle and cell membrane during internalization of nanoparticles through the membrane. This research can improve our fundamental understanding of cellular behavior and will be helpful for drug delivery applications. Based on conventional SICM, we have developed a novel method to simultaneous map the topography and potential distributions of the single living cells membranes. At the first step, multifunctional nanopipettes (nanopore/nanoelectrode) have been fabricated and characterized. To demonstrate the potential sensing capability and understand the mechanism, I measured the ionic current and local electric potential change during translocation of 40 nm charged gold nanoparticles. Our results reveal the capability of the multifunctional probe for the highly sensitive detection of the ionic current and local electrical potential changes during the translocation of the charged entity through the nanopore. From the potential change, we revealed the dynamic assembly of GNPs before entering the nanopore. The experimental results are also nicely explained by the finite element method based numerical simulation results. At the second step, I have measured the surface potential of living cell membrane at selected locations. Very recently, I have obtained results to show that we can map the extracellular membrane potential distribution of the complicated living cell membrane with sub-micron spatial resolution.This new imaging technique can help biologist to explore the extracellular potential distribution of varieties of cells quantitatively.These studies will have impacts on several biomedical applications such as regenerative repair and cancer treatment.

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Winchell, Stephen D. "Transport imaging in the one dimensional limit." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2006. http://library.nps.navy.mil/uhtbin/hyperion/06Jun%5FWinchell.pdf.

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Calvi, Ryan M. D. "Negative ion photoelectron imaging spectroscopy of iodine monobromide and copper hydrides." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1446093.

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Besztejan, Stephanie [Verfasser], and Andrea [Akademischer Betreuer] Rentmeister. "Metal Ion Based Probes for Imaging / Stephanie Besztejan. Betreuer: Andrea Rentmeister." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://d-nb.info/1111039119/34.

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Milgrew, Mark James. "An integrated CMOS sensor array technology for direct extracellular ion imaging." Thesis, University of Glasgow, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528663.

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18

Sage, Alan Graham. "Velocity mapped ion imaging studies of substituted aromatic and heteroaromatic molecules." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529835.

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Besztejan, Stephanie Verfasser], and Andrea [Akademischer Betreuer] [Rentmeister. "Metal Ion Based Probes for Imaging / Stephanie Besztejan. Betreuer: Andrea Rentmeister." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2016. http://nbn-resolving.de/urn:nbn:de:gbv:18-79705.

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20

Neugebohren, Jannis. "Implementing Ion Imaging to Probe Chemical Kinetics and Dynamics at Surfaces." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E43B-1.

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21

Guo, Ang. "Improving the performance of microscope mass spectrometry imaging." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:aa94a7f6-00ee-4b56-ba65-f6946799d5f2.

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Mass spectrometry imaging (MSI) is a powerful tool that provides mass-specific surface images with micron or sub-micron spatial resolutions. In a microscope MSI experiment, large sample surfaces are illuminated with a defocused laser or primary ion beam, enabling all surface molecules to be desorbed and ionised simultaneously before being electrostatically projected onto a position-sensitive imaging detector at the end of a time-of-flight mass analyser. Traditionally only the image of one mass-to-charge ratio can be obtained in a single acquisition, which limits its applicability. However, the development of event-triggered sensors, such as CMOS-based cameras, revives the microscope MSI method by allowing multi-mass imaging. Therefore, the challenges facing microscope have MSI shifted to improving its mass resolution, effective mass range, and mass accuracy. This thesis proposes effective solutions to each of them, and thus significantly improves the performance and applicability of microscope MSI. To increase the mass range, two modified post-extraction differential acceleration (PEDA) techniques, double-field PEDA and time-variable PEDA, were used to demonstrate mass-resolved stigmatic imaging over a broad m/z range. In double-field PEDA, a potential energy cusp was introduced into the ion acceleration region of an imaging mass spectrometer, creating two m/z foci that were tuned to overlap at the detector plane. This resulted in two focused m/z distributions that stretched the mass-resolved window with m/Îm >= 1000 to 165 Da without any loss in image quality; a range that doubled the 65 Da achieved under similar conditions using the original PEDA technique. In time-variable PEDA, a dynamic pulsed electric field was used to maximize the effective mass range of PEDA. By simultaneously focusing ions between 300 to 700 m/z using an exponentially rising voltage pulse, time-variable PEDA provides an effective mass range more than six times wider than the original PEDA method. Although reflectrons are widely used to improve the mass resolving power of ToF-MS, incorporating them in a microscope MSI instrument is novel. A reflectron MSI instrument was designed and implemented. Simulations demonstrated that one-stage gridless reflectrons were more compatible with the spatial imaging goal of the microscope MSI instrument than the gridded reflectrons. Preliminary experimental results showed that coupling the gridless reflectron with single-field PEDA achieved a mass resolution above 8,000 m/Îm while keeping a spatial resolution of 20 um. In conclusion, the gridless reflectron was able to triple the mass resolving power without losing any spatial imaging power. The poor mass accuracy hurdle was overcome by machine learning algorithms, which can construct clinical diagnostic models that recognise the peak pattern of biological mass spectra and classify them accurately without knowing the actual mass of each peak. After a proof of concept "experiment", where the mass spectra of dye molecules were classified by various learning algorithms, three pairs of datasets (ovarian cancer, prostate cancer, chronic fatigue and their respective controls) were used to build classifiers that accurately distinguish blood samples from controls. Possible biomarkers were also discovered by evaluating the importance of each m/z feature, which may assist further studies.

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22

Howie, Wendy Helen. "Molecular structure and predissociation dynamics studied using absorption spectroscopy and ion imaging." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364886.

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23

Finegan, D. P. "X-ray imaging of failure and degradation mechanisms of lithium-ion batteries." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1534606/.

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Lithium-ion batteries are becoming increasingly energy and power dense, and are required to operate in demanding applications and under challenging conditions. Both safety and performance of lithium-ion batteries need to be improved to meet the needs of the current demand, and are inextricably linked to their microstructure and mechanical design. However, there is little understanding of the complex, multi-length scale, structural dynamics that occur inside cells during operation and failure. From the evolving particle microstructure during operation to the rapid breakdown of active materials during failure, the plethora of dynamic phenomena is not well understood. In this thesis, both ex-situ and operando X-ray imaging, and computed tomography, in combination with image-based modelling and quantification are used to characterise battery materials and components in 3D. Degradation mechanisms are investigated across multiple length-scales, from the electrode particle to the full cell architecture, and direct comparisons between materials in their fresh and failed states are made. Rapid structural evolution that occurs during operation and failure is captured using high-speed synchrotron X-ray imaging, and quantified by correlating sequential tomograms. Consistent degradation mechanisms that occur over fractions of a second are identified and are shown to contribute significantly towards uncontrolled and catastrophic failure, and previously unexplored interplay between the mechanical design of cells and their safety and performance is described. The experiments reported here assess the thermal and mechanical responses of cells to extreme operating and environmental conditions. The interaction between the dynamic architecture of active materials and the mechanical designs of commercial cells are revealed, highlighting the importance of the engineering design of commercial lithium-ion batteries and their efficacy to mitigate failure. These insights are expected to influence the future design of safer and more reliable lithium-ion batteries.

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Winter, Benjamin. "Novel methods in imaging mass spectrometry and ion time-of-flight detection." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:43db5039-0490-4f97-8519-4d3ed4e30ca3.

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Imaging mass spectrometry (IMS) in microscope mode allows the spatially resolved molecular constitution of a large sample section to be analysed in a single experiment. If performed in a linear mass spectrometer, the applicability of microscope IMS is limited by a number of factors: the low mass resolving power of the employed ion optics; the time resolution afforded by the scintillator screen based particle detector and the multi-hit capability, per pixel, of the employed imaging sensor. To overcome these limitations, this thesis concerns the construction of an advanced ion optic employing a pulsed extraction method to gain a higher ToF resolution, the development of a bright scintillator screen with short emission lifetime, and the application of the Pixel Imaging Mass Spectrometry (PImMS) sensor with multi-mass imaging and time stamping capabilities. Initial experimental results employing a three electrode ion optic to spatially map ions emitted from a sample surface are presented. By applying a static electric potential a time-of-flight resolution of t/2Δt=54 and a spatial resolution of 20 μm are determined across a field-of-view of 4 mm diameter. While the moderate time-of-flight resolution only allows particles separated by a few Dalton to be distinguished, the instrument is used to demonstrate the multi-mass imaging capabilities of the PImMS sensor when being applied to image grid structures or tissue samples. An improved time-of-flight resolution is achieved by post extraction differential acceleration of a selected range of ions (up to 100 Da) using a newly developed five electrode ion optic. This modification is shown to correct the initial velocity spread of the ions coming off the sample surface, which yields an enhanced time-of-flight resolution of t/2Δt=2000 . The spatial resolution of the instrument is found to be 20 μm across a field-of-view of 4 mm. Adjusting the extraction field strength applied to the ion optic of the constructed mass spectrometer allows the optimised mass range to be tuned to any mass of interest. Ion images are recorded for various samples with comparable spatial and ToF resolution. Hence, studies on tissue sections and multi sample arrays become accessible with the improved design and operational principle of the microscope mode IMS instrument. A fast and efficient conversion of impinging ions into detectable flashes of light, which can consequently be recorded by a fast imaging sensor, is essential to maintain the achievable time-of-flight and spatial resolution of the IMS instrument constructed. In order to find a suitable fast and bright scintillator to be applied in a microchannel based particle detector, various inorganic and organic substances are characterised in terms of their emission properties following electron excitation. Poly-para-phenylene laser dye screens are found to show an outstanding performance among all substances analysed. An emission life time of below 4 ns and a brightness exceeding that of a P47 screen (industry standard) by a factor 2× is determined. No signal degradation is observed over an extended period, and the spatial resolution is found to be comparable to commercial imaging detectors. Hence, these scintillator screens are fully compatible with any ion imaging application requiring a high time resolution. In a further series of mass spectrometric experiments, ions are accelerated onto a scintillator mounted in front of a multi pixel photon counter. The charged particle impact stimulated the emission of a few photons, which are collected by the fast photon counter. Poly-para-phenylene laser dyes again show an outstanding efficiency for the conversion of ions into photons, resulting in a signal enhancement of up to 5× in comparison to previous experiments, which employed an inorganic LYSO scintillator.

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Price, Roosevelt Jerome. "Photodissociation studies with vacuum ultraviolet lasers by means of ion velocity imaging /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.

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Berrueta, Razo Irma. "Molecular imaging of mouse brain tissue using Cluster Time-of-Flight Secondary Ion Mass Spectrometry." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/molecular-imaging-of-mouse-brain-tissue-using-cluster-timeofflight-secondary-ion-mass-spectrometry(a350dc50-5337-4d32-a95c-24c617bbba97).html.

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ToF-SIMS imaging has been drawing attention due to the wide range of applications in the biological and biomedical fields. These applications include the acquisition of quantitative and qualitative data that ranges in scale from single cells to organs, image visualisation and interpretation of biomarkers for diagnosis and development of pharmaceutics. This study focused on molecular imaging of mouse brain tissue sections using cluster primary ion beams. First, cluster ion beams were applied to comparative background studies of biomolecules and brain total lipid extract. Enhancement of the secondary ion signal was observed using water-containing cluster primary ion beams, especially for [M+H]+ type secondary ions. Water-containing clusters were then used to acquire ToF-SIMS images from the cerebellar area of serial mouse brain tissue sections. Again, water-containing cluster beams produced the highest secondary ion yields in both grey and white matter, gaining a new level of insight into the lipid compositions of both types of tissue in the brain. A clinical case was also evaluated with ToF-SIMS imaging, using cluster beams for the analysis of 3xTg-AD mouse brain tissue. SIMS images were registered with fluorescence microscopy images for the in situ identification and co-localisation of the Amyloid-β plaques on the SIMS images. Spectra from regions of interest were analysed to identify possible ion fragments derived from the Aβ protein. The co-localisation of cholesterol was also studied from images obtained with different primary ion beams. The results presented show that cluster ToF-SIMS can be successfully applied to brain tissue imaging. New primary ion beam technologies allow us to acquire data with more useful secondary ion yield for clinical applications and biological research. Nevertheless, future technological improvements are required for specialised applications e.g. cellular imaging. Moreover, processing the data obtained is still challenging and more data processing tools are also needed for interpretation.

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Norton, Benjamin Geoffrey. "High Resolution Imaging of Single Trapped Yb+ Ions Using A Phase Fresnel Lens." Thesis, Griffith University, 2015. http://hdl.handle.net/10072/366427.

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The thesis describes the use of a high numerical aperture phase Fresnel lens for high resolution ion imaging and scalable fluorescence collection. We have demonstrated the first step towards fabricating and integrating a scalable collection optic with an ion trap with applications towards large scale ion trap quantum computers. I outline the use of the lens for capturing high resolution images of trapped ions. Using these high resolution images we have demonstrated spatial thermometry, a thermometry technique which relies on imaging the small changes in the ion spot size as the ion temperature changes. By adding a beam propagating along the optic axis of the imaging system we have also been able to use the high resolution imaging system to observe the absorption image from a single atom. We have verified that the contrast of the absorption images was the maximum achievable with our imaging system according to theory. Finally, using the absorption images we have been able to observe the phase shift of the light scattered by the atom with respect to the illumination field. The observed phase shift was found to be the maximum allowed by theory.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Biomolecular and Pysical Sciences
Science, Environment, Engineering and Technology
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Warner, Joshua Dale. "Kidney segmentat ion and image analysis in autosomal dominant polycystic kidney disease." Thesis, College of Medicine - Mayo Clinic, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10111486.

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Autosomal Dominant Polycystic Kidney Disease (ADPKD) is among the most prevalent life-threatening genetic conditions. Despite this, no approved medical therapies exist to treat the disease. Until the recent past, no methods could reliably measure the course of the disease far in advance of end stage renal disease (ESRD). As normal tissue is progressively destroyed or blocked by enlarging cysts, remaining nephrons compensate in a process called hyperfiltration. This beneficial physiological response confounds tests of renal function. Thus, potential interventions could not be tested against a reliable measurement of disease progression.

However, progressive changes are visually apparent on medical imaging examinations throughout the course of ADPKD. The search for ADPKD proxy biomarkers is now focused on quantitative imaging, or the extraction of information from medical images for purposes of diagnosis or disease tracking. Recent studies from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)- sponsored Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP) showed Total Kidney Volume (TKV) is a usable quantitative imaging biomarker which can track disease in the early, asymptomatic phase and register measurable changes in as little as 12 months. These findings launched several new trials into potential ADPKD therapies.

Advanced analysis of polycystic kidney images, however, has never been done. The method CRISP used to extract TKV was stereology, an efficient means to estimate volume. However, stereology was tradi- tionally a dead end for further advanced analysis. TKV is useful for clinical trials and large population-based studies, but cannot accurately predict disease progression or stratify risk due to known out- lier cases. Thus, the utility of TKV for individual patient prognosis is limited. This work builds upon stereology data, describing a reliable and accurate new semi-automatic method to fully segment images us- ing only labeled stereology grids. Then, two new second generation quantitative imaging biomarkers are introduced and analyzed: Cyst- Parenchyma Surface Area (CPSA) and cyst concentration. These new physiologically motivated biomarkers will complement or potentially replace TKV in efforts to bring quantitative imaging to individual patients.

The goal of this body of work is to enable a pathway for efficient advanced image analysis in ADPKD, never before attempted in this dis- order, and to define new quantitative imaging biomarkers which will complement or replace existing ones in hopes of making individualized disease tracking for ADPKD patients a reality.

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Stephenson, David E. "Microstructure and Transport Properties of Porous Li-ion Electrodes." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2752.

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The goal of this work is to understand the relationships between electrode microstructure and mass transport resistances. One can use this information to predict cell performance from fundamental principles. This work includes new types of particle-scale 3D models for correlating and predicting the effects of electrode microstructure on both ionic and electronic transport. The 3D models imitate the sub-micrometer-scale arrangement of active material particles, carbon, binder, and pores and use FIB/SEM images as a basis for parameterization. The 3D models are based respectively on the statistical mechanics techniques of molecular dynamics and Monte Carlo. The approach closely related to molecular dynamics, named the dynamic particle packing (DPP) model, uses aggregates of spheres to recreate electrode microstructures. The other approach, named the stochastic grid (SG) model, is closely related to Monte Carlo techniques in which a small set of fundamental interdomain and bulk energy parameters are used to generate structures.In order to predict electrode microstructures we correlated the fundamental interdomain and bulk energy parameters for the SG model to electrode mass composition and porosity. We used the revised computer program, known as predict SG, to estimate structures of which there are no experimental measurements of electrode structure. From these predicted electrode structures we obtained electronic and ionic transport properties. This allowed us to estimate the trade-offs between ionic and electronic transport for different porosities and carbon fractions. We found from experimental measurements of electrode structure that carbon and binder formed distinct agglomerates. From the 3D models we determined at commercial fractions of carbon and binder that the conductivity of these carbon agglomerates plays a large role in determining both the electronic and ionic pathways. So in order to better understand the role that these carbon/binder agglomerates play, we explored and developed several experimental methods to find the electronic and ionic conductivity of both simulated carbon domains and complete electrode films. The goal was not only to elucidate the role carbon agglomerates play, but also to develop a non-destructive method of determining overall film properties. Although we found that a non-destructive method is extremely challenging due to probe contact resistances, we did find success in determining carbon domain properties using a delamination method.

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Maharjan, Chakra Man. "Momentum imaging studies of electron and ion dynamics in a strong laser field." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/378.

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31

Brahmi, Chloé. "Study of scleractinian coral biomineralization using ⁸⁶Sr-labeling and NanoSIMS ion-microprobe imaging." Paris, Muséum national d'histoire naturelle, 2012. http://www.theses.fr/2012MNHN0042.

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Les coraux Scléractiniaires produisent un exosquelette en carbonate de calcium (aragonite). Leurs processus de biominéralisation ont été étudiés chez trois espèces présentant différents taux de croissance et vivant ou non en symbiose avec les zooxanthelles. Une hétérogénéité de composition du tissu et du squelette a été mise en évidence, à différentes échelles, via des techniques d’observations et de micro-analyses, à haute résolution spatiale. Un thème central a été le développement et l’application d’une méthode de marquage de biocarbonates marins basée sur un enrichissement avec un isotope stable d’un élément trace, naturellement présent dans l’eau de mer (86Sr). Le biocarbonate formé, présentant des enrichissements isotopiques correspondants, est ensuite imagé à la NanoSIMS afin de visualiser, à l’échelle submicrométrique, les zones formées durant le marquage. Cette technique permet ainsi de résoudre les détails ultrastructuraux et accéder à la dynamique de croissance squelettique
Scleractinian corals build an aragonitic calcium carbonate exoskeleton. Their biomineralization processes have been studied in three different scleractinian species with or without zooxanthellae and with different growth rates. Heterogeneity of the tissue and the skeletal compositions was revealed at different length scales, using complementary observations and micro-analytical techniques at high spatial resolution. A central theme was the development and application of a method to label marine biocarbonates through a concentration-enrichment of a minor stable isotope of a trace element that is a natural component of seawater (86Sr), resulting in the formation of biocarbonate with corresponding isotopic enrichments. This biocarbonate was subsequently imaged with a NanoSIMS ion microprobe to visualize the locations of the isotopic marker on submicrometric length scales, permitting resolution of all ultra-structural details and access to the skeletal growth dynamics

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Villacob, Raul A. "Development of a Primary Ion Column for Mass Spectrometry-Based Surface Analysis." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2561.

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Secondary Ion Mass Spectrometry (SIMS) is a powerful technique for high spatial resolution chemical mapping and characterization of native surfaces. The use of massive cluster projectiles has been shown to extend the applicable mass range of SIMS and improve secondary ion yields 100 fold or beyond. These large projectiles however, present a challenge in terms of focusing due to the initial spatial and kinetic energy spreads inherent to their generation. In the present work, we describe the development and construction of a novel primary ion (PI) column employing a gold nanoparticle – liquid metal ion source (AuNP-LMIS) and the coupling to ultrahigh resolution mass spectrometers (e.g., Fourier Transform Ion Cyclotron Resonance Mass Spectrometer, FT-ICR MS) for accurate chemical characterization of complex biological surfaces. This work describes the ion dynamics, development and the experimental characterization of the AuNP-LMIS.

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Uhlén, Per. "Signal transduction via ion fluxes : a cell imaging study with emphasis on calcium oscillations /." Stockholm, 2002. http://diss.kib.ki.se/2002/91-7349-188-8.

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Richard, Marie-Hélène. "Design study of a Compton camera for prompts-gamma imaging during ion beam therapy." Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00934715.

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Ion beam therapy is an innovative radiotherapy technique using mainly carbon ion and proton irradiations. Its aim is to improve the current treatment modalities. Because of the sharpness of the dose distributions, a control of the dose if possible in real time is highly desirable. A possibility is to detect the prompt gamma rays emitted subsequently to the nuclear fragmentations occurring during the treatment of the patient. In a first time two different Compton cameras (double and single scattering) have been optimised by means of Monte Carlo simulations. The response of the camera to a photon point source with a realistic energy spectrum was studied. Then, the response of the camera to the irradiation of a water phantom by a proton beam was simulated. It was first compared with measurement performed with small-size detectors. Then, using the previous measurements, we evaluated the counting rates expected in clinical conditions. In the current set-up of the camera, these counting rates are pretty high. Pile up and random coincidences will be problematic. Finally we demonstrate that the detection system is capable to detect a longitudinal shift in the Bragg peak of +or- 5 mm, even with the current reconstruction algorithm.

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Rinaldi, Ilaria [Verfasser], and Katia [Akademischer Betreuer] Parodi. "Investigation of novel imaging methods using therapeutic ion beams / Ilaria Rinaldi ; Betreuer: Katia Parodi." Heidelberg : Universitätsbibliothek Heidelberg, 2011. http://d-nb.info/1179230353/34.

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Iskra, Andreas. "Photofragmentation studies of metal ion-molecule complexes and metal oxides." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:d3663b37-7954-47a3-83e3-4a9ad7b9e3e7.

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Gas phase metal-containing complexes provide suitable systems in which to study fundamental binding motifs between a metal ion and molecules in the absence of any solvent, support or competing charge effects. In this thesis, metal-containing species are explored experimentally using infrared resonance enhanced photodissociation (IR-REPD) spectroscopy and velocity map imaging (VMI). The experimental results are further interpreted with the aid of spectral simulations based on density functional theory (DFT). These are the first studies reported using a newly built IR-REPD spectrometer equipped with a purpose-built laser ablation source to allow for the study of single metal ion-molecule complexes. The laser ablation source is shown to efficiently produce various complexes including Rh⁺(CO₂)_n, VO₂⁺(N₂O)_n and Au⁺(CH₄)_n and the IR-REPD spectrometer has been characterised against a well-studied system of V⁺(CO₂)_n complexes. In order to record the IR-REPD spectra for small metal ion-molecule complexes, an argon atom is employed as the inert messenger. A combined IR-REPD spectroscopy and DFT investigation of M⁺(CO₂)_n complexes (where M = Co⁺, Rh⁺ and Ir⁺) reveals a common [M⁺(CO₂)₂] core structure for all three considered metal ions. Additional ligands, which are not directly bound to the central metal ion, experience lower perturbation as evident in the reduced blue-shift for the ligand in the outer coordination shells. A further IR-REPD/DFT study involving CO₂ complexation around NbO₂⁺ and TaO₂⁺ ions reveals a strongly-bound core of four CO₂ ligands around the MO₂⁺ ion (M = Nb, Ta). A significant increase in the intermolecular bond distances for the second coordination sphere ligands coincides with a decrease in the calculated binding energies. Velocity map imaging is employed to explore the rich photodissociation dynamics of VO in the vicinity of C⁴Î£- - X⁴Î£-(v',0) vibronic transitions in VO. The final quantum state distribution was observed to be strongly dependent on the intermediate vibronic state of VO via which the dissociation threshold is reached. This work provides a refined value for the VO dissociation energy of D₀(VO) = 53190 ± 261 cm^-1 in excellent agreement with available literature.

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Clarson, Benjamin B. "Spectroscopic and ion imaging studies of the Rydberg states of NO in homogenous electric fields." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496838.

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Domesle, Christian [Verfasser], and Andreas [Akademischer Betreuer] Wolf. "Momentum Imaging of Photofragments and Photoelectrons using Fast Ion Beams / Christian Domesle ; Betreuer: Andreas Wolf." Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/117978605X/34.

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Jiang, Haibo. "Exploiting stable isotope imaging with high resolution secondary ion mass spectrometry for applications in biology." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:15456362-6022-41e1-b78d-1127d6d172b0.

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This thesis presents applications of high resolution secondary ion mass spectrometry (NanoSIMS) analysis for stable isotope imaging in biological samples. These projects were designed to explore the potential applications of NanoSIMS analysis, and to develop protocols and novel methodologies to visualize and quantify biological processes. Working with collaborators in the UK and USA, I have applied NanoSIMS analysis to study 3 research areas, including molecule interactions, single cell metabolisms and lipid imaging in tissues. Antimicrobial peptides (AMPs) play important role in the immune system, and understanding how AMPs interact with cell membranes can provide useful information to design new therapies to control infection. The pore structures and dynamics of the interaction of AMPs with membranes has been visualized for the first time and confirmed with combined AFM and NanoSIMS analysis. A correlative backscattered electron (BSE) imaging and NanoSIMS analysis methodology has been developed to study glutamine metabolism in single cancer cells. This method enables us to measure the chemical information in specific organelles in these cells and can be widely applied to study metabolisms and to trace the uptake of labelled molecules in biological matrices. Quantitative analysis on the effects of hypoxic conditions and the PYGL gene were studied. Applying correlative BSE and NanoSIMS analysis, I also studied lipid uptake mechanisms in various mouse tissues, including brown adipose tissue, heart, intestines, liver and skeletal muscle, mainly focused on a recently discovered protein, GPIHBP1, and its function in the lipid uptake process. TRL margination was proved to depend on the GPIBP1-LPL complex, and 3 stages of lipid transport from capillary lumen to lipid droplets was also visualized by combined BSE and NanoSIMS analysis.

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Van, Nuffel Sebastiaan. "Three-dimensional time-of-flight secondary ion mass spectrometry imaging of primary neuronal cell cultures." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39644/.

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Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has proven its ability to characterise (in)organic surfaces, and is increasingly used for the characterisation of biological samples such as single cells. By combining ion imaging and molecular depth profiling it is possible to render 3D chemical images, which provides a novel, label-free way to investigate biological systems. Major challenges lie, however, in the development of data analysis tools and protocols that preserve the cell morphology. Here, we develop and employ such tools and protocols for the investigation of neuronal networks. One of the reasons 3D ToF-SIMS imaging of cells is underused is the lack of powerful data analysis tools as 3D ToF-SIMS measurements generate very large data sets. To address this issue, we developed a method that allows the application of principal component analysis (PCA) to be expanded to large 3D images making 3D ToF-SIMS image processing of whole, intact cells and cellular networks with multivariate analysis now accessible on a routine basis. Using this method, we are able to separate cellular material from the substrate and can then correct z-offsets due to the cells' topography resulting in a more accurate surface heightmap. The method also facilitates differentiation between cellular components such as lipids and amino acids allowing the cell membrane, the cytoplasm and the extracellular matrix (ECM) to be easily distinguished from one another. These developments permit us to investigate the intracellular localisation of specific native and non-native compounds label-free, not just in single cells but also in larger cellular networks. The visualisation of the cellular uptake of non-native compounds, namely fluorescent dyes, in primary rat cortical neurons and the chemical differentiation between cell types, namely primary rat cortical neurons and retinal pigment epithelium (RPE) cells, are presented as applications. Even though the dyes have distinct fragment ions in the high mass range, it was not possible to detect the fluorophores by 3D ToF-SIMS imaging of freeze-dried cells. However, it was possible to detect distinct differences in the kind of ions detected for freeze-dried primary rat cortical neurons and RPE cells albeit in the low mass range. To obtain meaningful results, however, it is paramount that sample preparation does not induce significant physical or chemical changes. We present the first comprehensive comparison between large 3D ToF-SIMS images of freeze-dried and frozen-hydrated cells using PCA to facilitate the data analysis of these large data sets. A higher degree of colocalisation of the K+ signal with cell regions is observed for frozen-hydrated cells, which indicates a lower degree of membrane damage and migration of diffusible chemical species. Frozen-hydrated cell samples are therefore considered to best reflect the native cell state, but freeze-dried cell samples allow far easier sample handling. The mass spectrum of frozen-hydrated cellular material also has increased ion intensities for higher-mass fragments, which is an additional advantage, because the poor signal-to-noise ratio of molecular species with m/z > 200 is a major bottleneck in the advancement of ToF-SIMS imaging as a diagnostic tool.

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Sandvold, Marianne. "Technical Aspects of Ion Milling and Electron Imaging of Epoxy Embedded Samples for FIB/SEM Tomography." Thesis, Norges Teknisk-Naturvitenskaplige Universitet, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20916.

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FIB/SEM tomography is a relatively new imaging technique for 3D investigation of biological tissue. It uses a dualbeam FIB/SEM instrument to alternately image a sample surface with an electron beam and mill off successive slices with an ion beam, collecting a series of images representing the investigated volume. This technique was employed to study alumina nanoparticles, brain tissue and tissue engineered cartilage embedded in epoxy. Hydrocarbon deposition of contamination layers as well as suboptimal sample geometry, were shown to be issues for imaging experiments. It was important to ensure that sample blocks were cut smoothly, and that the material of interest was concentrated at an edge. The alumina nanoparticle sample was used as a model specimen to investigate the volume of origin of signals detected for image formation at different acceleration voltages. This was shown to have a reasonable correspondance with Monte Carlo simulation results. Imaging and Slice and View experiments on the biological samples showed that FIB/SEM tomography can resolve structures below 10nm in size, and that detailed 3D models from properly stained tissue are obtainable. In summary FIB/SEM tomography constitutes a valuable 3D imaging technique for biological samples.

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Giesecke, Marianne. "Characterizing ions in solution by NMR methods." Doctoral thesis, KTH, Tillämpad fysikalisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-149552.

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NMR experiments performed under the effect of electric fields, either continuous or pulsed, can provide quantitative parameters related to ion association and ion transport in solution. Electrophoretic NMR (eNMR) is based on a diffusion pulse-sequence with electric fields applied in the form of pulses. Magnetic field gradients enable the measurement of the electrophoretic mobility of charged species, a parameter that can be related to ionic association. The effective charge of the tetramethylammonium cation ion in water, dimethylsulphoxide (DMSO), acetonitrile, methanol and ethanol was estimated by eNMR and diffusion measurements and compared to the value predicted by the Debye-Hückel-Onsager limiting law. The difference between the predicted and measured effective charge was attributed to ion pairing which was found to be especially significant in ethanol. The association of a large set of cations to polyethylene oxide (PEO) in methanol, through the ion-dipole interaction, was quantified by eNMR. The trends found were in good agreement with the scarce data from other methods. Significant association was found for cations that have a surface charge density below a critical value. For short PEO chains, the charge per monomer was found to be significantly higher than for longer PEO chains when binding to the same cations. This was attributed to the high entropy cost required to rearrange a long chain in order to optimize the ion-dipole interactions with the cations. Moreover, it was suggested that short PEO chains may exhibit distinct binding modes in the presence of different cations, as supported by diffusion measurements, relaxation measurements and chemical shift data. The protonation state of a uranium (VI)-adenosine monophosphate (AMP) complex in aqueous solution was measured by eNMR in the alkaline pH range. The question whether or not specific oxygens in the ligand were protonated was resolved by considering the possible association of other species present in the solution to the complex. The methodology of eNMR was developed through the introduction of a new pulse-sequence which suppresses artifactual flow effects in highly conductive samples. In another experimental setup, using NMR imaging, a constant current was applied to a lithium ion (Li ion) battery model. Here, 7Li spin-echo imaging was used to probe the spin density in the electrolyte and thus visualize the development of Li+ concentration gradients. The Li+ transport number and salt diffusivity were obtained within an electrochemical transport model. The parameters obtained were in good agreement with data for similar electrolytes. The use of an alternative imaging method based on CTI (Constant Time Imaging) was explored and implemented.

QC 20140825

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Venugopal, Vinithra. "Kinetics of Ion Transport in Conducting Polymers." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1458229667.

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Ahuja, Punkaj N. "Optode-bead-based Functional Chemical Imaging of 2D Substrates." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1307727754.

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45

Zimmerer, Cordelia. "Entwicklung eines optischen markierungsfreien Ionenkanalsensor-Arrays." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1193247156004-79633.

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Ligandgesteuerte Ionenkanäle sind Membranproteine, die an der Weiterleitung von Reizen und an der Kommunikation zwischen Zellen beteiligt sind. Große Bedeutung besitzt die Messung der Aktivierung der Ionenkanäle beispielsweise in der Medizin (z.B. Ionenkanalerkrankungen), der Pharmazie (z.B. Medikamenten-Screening) und in der Bionanotechnologie (z.B. molekulare Schalter). In all diesen Gebieten besteht die Forderung nach hohen Probendurchsätzen bei sehr hohem Informationsgehalt. Etablierte elektrochemische Detektionsmethoden erfüllen diese Forderung nicht. Um dieses Defizit zu überwinden, wurde ein Ionenkanalsensor-Array mit optischer, paralleler Detektion entwickelt. Eine mikrostrukturierte Polymethyl(meth)acrylat (PMMA)-Schicht dient als Grundgerüst des Arrays. Über die Mikroporen, die nur wenige Mikrometer Durchmesser aufweisen, wird eine Lipidmembran gespannt, in die Ionenkanäle eingebaut werden. Wird der Ionenkanal aktiviert, strömen Ionen in die Mikroporen und führen zu einer messbaren Veränderung des Brechungsindexes. Mittels Oberflächenplasmonen-Resonanz Imaging lässt sich die Aktivierung der Ionenkanäle markierungsfrei und direkt bestimmen. Stabile, die Mikrostruktur überspannende Lipidmembranen wurden durch eine neu entwickelte Stempeltechnik und durch eine Oberflächenmodifikation der PMMA-Mikrostruktur erzielt. Für die Charakterisierung und den Funktionsnachweis des Sensoraufbaus wurden das infrarot-spektroskopische Imaging und die Fluoreszenzmikroskopie eingesetzt. Schließlich konnte gezeigt werden, dass eine Verbesserung der Empfindlichkeit durch das lokale Aufkonzentrieren der durch den Ionenkanal geströmten Metallionen am Porengrund mit oberflächengebundener 2-(Benzylsulfid)-18-Krone-6 möglich ist.

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Walton, Barbara Lynn. "A Study of Silver: an Alternative Maldi Matrix for Low Weight Compounds and Mass Spectrometry Imaging." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc499981/.

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Soft-landing ion mobility has applicability in a variety of areas. The ability to produce material and collect a sufficient amount for further analysis and applications is the key goal of this technique. Soft-landing ion mobility has provided a way to deposit material in a controllable fashion, and can be tailored to specific applications. Changing the conditions at which soft-landing ion mobility occurs effects the characteristics of the resulting particles (size, distribution/coverage on the surface). Longer deposition times generated more material on the surface; however, higher pressures increased material loss due to diffusion. Larger particles were landed when using higher pressures, and increased laser energy at ablation. The utilization of this technique for the deposition of silver clusters has provided a solvent free matrix application technique for MALDI-MS. The low kinetic energy of incident ions along with the solvent free nature of soft-landing ion mobility lead to a technique capable of imaging sensitive samples and low mass analysis. The lack of significant interference as seen by traditional organic matrices is avoided with the use of metallic particles, providing a major enhancement in the ability to analyze low mass compounds by MALDI.

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Ghous, Abid Petroleum Engineering Faculty of Engineering UNSW. "3D imaging and modeling of carbonate core at multiple scales." Awarded By:University of New South Wales. Petroleum Engineering, 2010. http://handle.unsw.edu.au/1959.4/44606.

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The understanding of multiphase flow properties is essential for the exploitation of hydrocarbon reserves in a reservoir; these properties in turn are dependent on the geometric properties and connectivity of the pore space. The determination of the pore size distribution in carbonate reservoirs remains challenging; carbonates exhibit complex pore structures comprising length scales from nanometers to several centimeters. A major challenge to the accurate evaluation of these reservoirs is accounting for pore scale heterogeneity on multiple scales. This is the topic of this thesis. Conventionally, this micron scale information is achieved either by building stochastic models using 2D images or by combining log and laboratory data to classify pore types and their behaviour. None of these capture the true 3D connectivity vital for flow characterisation. We present here an approach to build realistic 3D network models across a range of scales to improve property estimation through employment of X-ray micro-Computed Tomography (μCT) and Focussed Ion Beam Tomography (FIBT). The submicron, or microporous, regions are delineated through a differential imaging technique undertaken on x-ray CT providing a qualitative description of microporosity. Various 3-Phase segmentation methods are then applied for quantitative characterisation of those regions utilising the attenuation coefficient values from the 3D tomographic images. X-ray micro-CT is resolution limited and can not resolve the detailed geometrical features of the submicron pores. FIB tomography is used to image the 3D pore structure of submicron pores down to a scale of tens of nanometers. We describe the experimental development and subsequent image processing including issues and difficulties resolved at various stages. The developed methodology is implemented on cores from producing wackstone and grainstone reservoirs. Pore network models are generated to characterise the 3D interconnectivity of pores. We perform the simulations of petrophysical properties (permeability and formation resistivity) directly on the submicron scale image data. Simulated drainage capillary pressure curves are matched with the experimental data. We also present some preliminary results for the integration of multiscale pore information to build dual-scale network models. The integration of multiscale data allows one to select appropriate effective medium theories to incorporate sub-micron structure into property calculations at macro scale giving a more realistic estimation of properties.

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Castro, Olivier de. "Development of a Versatile High-Brightness Electron Impact Ion Source for Nano-Machining, Nano-Imaging and Nano-Analysis." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS468/document.

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Les nano-applications utilisant des faisceaux d'ions focalisés nécessitent des sources d'ions à haute brillance avec une faible dispersion en énergie (ΔE) ce qui permet une excellente résolution latérale et un courant d'ions suffisamment élevé pour induire des vitesses d'érosion raisonnables et des rendements élevés d'émission électronique et ionique. Les objectifs de cette thèse sont le développement d'une source d'ions basée sur l'impact électronique ayant une brillance réduite Br de 10³ – 10⁴ A m⁻² sr ⁻ ¹ V⁻ ¹, une dispersion en énergie ΔE ≲ 1 eV et un choix polyvalent d'ions. Le premier concept évalué consiste à focaliser un faisceau d'électrons à une énergie de 1 keV entre deux électrodes parallèles distant de moins d'un millimètre. Le volume d'ionisation « micrométrique » est formé au-dessus d'une ouverture d'extraction de quelques dizaines de µm. En utilisant un émetteur d'électrons LaB₆ et une pression de 0.1 mbar dans la région d'ionisation, Br est proche de 2.10² A m⁻² sr ⁻ ¹ V ⁻ ¹ avec des tailles de source de quelques µm, des courants de quelques nA pour Ar⁺/Xe⁺/O₂ ⁺ et une dispersion en énergie ΔE < 0.5 eV. La brillance réduite Br est encore en dessous de la valeur minimum de notre objectif et la pression de fonctionnement très faible nécessaire pour l'émetteur LaB₆ ne peut être obtenue avec une colonne d'électrons compacte, donc ce prototype n'a pas été construit.Le deuxième concept de source d'ions évalué est basé sur l’idée d’obtenir un faisceau ionique à fort courant avec une taille de source et un demi-angle d’ouverture similaire aux résultats du premier concept de source, mais en changeant l’interaction électron-gaz et la collection des ions. Des études théoriques et expérimentales sont utilisées pour l’évaluation de la performance de ce deuxième concept et de son utilité pour les nano-applications basées sur des faisceaux d'ions focalisés
High brightness low energy spread (ΔE) ion sources are needed for focused ion beam nano-applications in order to get a high lateral resolution while having sufficiently high ion beam currents to obtain reasonable erosion rates and large secondary electron/ion yields. The objectives of this thesis are: the design of an electron impact ion source, a reduced brightness Br of 10³ – 10⁴ A m⁻² sr⁻ ¹ V⁻ ¹ with an energy distribution spread ΔE ≲ 1 eV and a versatile ion species choice. In a first evaluated concept an electron beam is focussed in between two parallel plates spaced by ≲1 mm. A micron sized ionisation volume is created above an extraction aperture of a few tens of µm. By using a LaB₆ electron emitter and the ionisation region with a pressure around 0.1 mbar, Br is close to 2.10² A m⁻² sr ⁻ ¹ V ⁻ ¹ with source sizes of a few µm, ionic currents of a few nA for Ar⁺/Xe⁺/O₂ ⁺ and the energy spread being ΔE < 0.5 eV. The determined Br value is still below the minimum targeted value and furthermore the main difficulty is that the needed operation pressure for the LaB₆ emitter cannot be achieved across the compact electron column and therefore a prototype has not been constructed. The second evaluated source concept is based on the idea to obtain a high current ion beam having a source size and half-opening beam angle similar to the first concept, but changing the electron gas interaction and the ion collection. Theoretical and experimental studies are used to evaluate the performance of this second source concept and its usefulness for focused ion beam nano-applications

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Schiller, Michael [Verfasser], and Karl-Heinz [Akademischer Betreuer] Gericke. "3D Ion Imaging: Elektronische Struktur, Zerfallsdynamik und Anisotropie der Photodissoziation von DCl / Michael Schiller ; Betreuer: Karl-Heinz Gericke." Braunschweig : Technische Universität Braunschweig, 2017. http://d-nb.info/1175817066/34.

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Chen, Yuxiu. "Manipulation and imaging of interactions between layer-by-layer capsules and live cells using nanopipettes and SICM." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/54023.

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Usability of many chemical substances with significant potential for biomedical applications is limited by their poor solubility in water or limited stability in the physiological environment. One of promising strategies for therapeutic targeted delivery of these types of substances into cells and tissues is their encapsulation inside polyelectrolyte microcapsules (Volodkin et al., 2004b, Sukhorukov et al., 1998b). Successful internalisation of microcapsules loaded with various macromolecules have been observed in several types of living cells (Javier et al., 2008, Kastl et al., 2013), however the mechanisms of the uptake of capsules by living cells are not yet fully understood. Detailed understanding of physico-chemical and mechanical interactions between capsules and living cells is required for specific targeting, effective delivery, and elimination of any potential toxic side effects. This has been largely limited by capabilities of available imaging techniques and lack of specific fluorescent markers for certain types of cellular uptake. The rate of internalisation of microcapsules was primarily studied at the level of cell population using conventional optical/fluorescence microscopy, confocal microscopy, and flow cytometry (Gao et al., 2016, Ai et al., 2005, Sun et al., 2015). These conventional fluorescence methods are known to be prone to overestimating the number of internalised capsules due to their limited capability to exclude capsules which were not fully internalised and remained attached to the cell surface (Javier et al., 2006). Experimental evidence with resolution high enough to resolve the fine membrane processes interacting with microcapsules has been limited to fixed samples imaged by scanning electron microscopy and transmission electron microscopy (Kastl et al., 2013) capturing randomly timed "snapshots" of what is likely to be highly dynamic and complex interaction. Physical force interactions between cellular membrane and capsules during the internalisation were suggested to cause buckling of capsules based on indirect evidence obtained using fluorescence microscopy in live cells 15 (Palankar et al., 2013) and separate measurements of capsule deformation under colloidal probe atomic force microscopy (AFM) outside of the cellular environment (Delcea et al., 2010, Dubreuil et al., 2003). However, our knowledge of the mechanical properties of the fine membrane structures directly involved in the internalisation process or how these structures form during the internalisation is very limited, if non-existent. Here we employ a different approach based on a high-resolution scanning probe technique called scanning ion conductance microscopy (SICM). SICM uses reduction in ionic current through the probe represented by an electrolyte-filled glass nanopipette immersed in saline solution to detect proximity of sample surface (Hansma et al., 1989, Korchev et al., 1997a). The technique has been previously used for high-resolution scanning of biological samples of complexity similar to what can be expected in case of microcapsules interacting with cells (Novak et al., 2014, Novak et al., 2009), and also for mapping mechanical properties at high resolution (Ossola et al., 2015, Rheinlaender and Schaffer, 2013). It has been proved to be able to visualise internalisation process of 200 nm carboxy-modified latex nanoparticles (Novak et al., 2014), however it is not clear whether it would be suitable for visualising internalisation of substantially larger, microscale-sized particles. The aim of this research was to visualize the live internalisation process of microcapsules entering cells by using SICM. The first two chapters of this thesis are introduction and literature review, which summarise the current state of the art. Chapter 3 states the aim and objectives of this study. Chapter 4 introduces the materials and methods we used in our research. Chapter 5, 6, 7 present the main findings of our research. Chapter 5 states the challenges we met in visualising the live internalisation of microcapsule as well as our solution for overcoming those challenges. At the end of that chapter, we describe the detailed procedure we used for recording the live internalisation of microcapsules. The results we got using this procedure are presented in chapter 6 and 7. In chapter 8, we discuss the results we found by comparing them to the results of previous research. In chapter 9, we summarise our study and give some suggestions on future work.

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Dissertations / Theses on the topic 'Ion imaging'

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