Dissertations / Theses: 'Laser Fluorescence Imaging'

1

Tecu, Kirk S. "Laser induced fluorescence imaging of counterflow diffusion flames /." free to MU campus, to others for purchase, 1997. http://wwwlib.umi.com/cr/mo/fullcit?p9841342.

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Sasaki, K., S. Matsui, H. Ito, and K. Kadota. "Dynamics of laser-ablation Ti plasmas studied by laser-induced fluorescence imaging spectroscopy." American Institute of Physics, 2002. http://hdl.handle.net/2237/7045.

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3

Capewell, Dale L. Goodwin David G. Goodwin David G. "Planar laser induced fluorescence imaging and Monte Carlo simulations of pulsed laser ablation /." Diss., Pasadena, Calif. : California Institute of Technology, 1997. http://resolver.caltech.edu/CaltechETD:etd-01102008-095243.

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4

Ombinda-Lemboumba, Saturnin. "Laser induced chlorphyll fluorescence of plant material." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/3064.

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Thesis (MSc (Physics))--University of Stellenbosch, 2007.
Imaging and spectroscopy of laser induced chlorophyll fluorescence (LICF) are emerging as useful tools in plant physiology and agriculture since these methods allow an early detection of plant stress and transformation of plant tissue, before visual symptoms appear. Chlorophyll fluorescence is governed by photosynthetic efficiency and it depends on the plant species and physiological state. In addition, the laser induced fluorescence of chlorophyll molecules in the red and far red spectral range is also used to study basic processes and phenomena in photo-excited molecules. In the work reported here experimental setups used for laser induced chlorophyll fluorescence imaging and spectroscopy techniques were developed to investigate chlorophyll fluorescence under constant illumination and also to detect green-fluorescent protein (GFP) by looking at the chlorophyll fluorescence spectrum and image. He-Ne (wavelength 632 nm), tunable argon ion (wavelength 455 nm), and excimer (wavelength 308 nm) lasers were used as excitation sources. An Ocean Optics spectrometer was used to record the spectrum of the chlorophyll fluorescence and the variation of the chlorophyll fluorescence spectrum with time. The chlorophyll fluorescence spectrum of tobacco leaves expressing GFP was compared to that of control leaves. A charge-coupled device (CCD) camera was used to image the fluorescence from GFP expressing and control tobacco leaves to investigate the effect of GFP genes on chlorophyll fluorescence in relation to the state of the plant material. The spectral analysis technique and image processing procedures were elaborated in order to obtain better information on chlorophyll fluorescence. The results of this work show that the experimental setups and analytical procedures that were devised and used are suitable for laser induced chlorophyll fluorescence analysis. Fluorescence bleaching could be obtained from the time variation of the fluorescence spectrum, and plant expressing GFP can be distinguished from control plants by differences in the laser induced chlorophyll fluorescence.

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5

Jiang, Naibo. "Development of high repetition rate no planar laser induced fluorescence imaging." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1150140816.

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6

Elson, Daniel S. "Development of ultrafast laser technology and its application to fluorescence lifetime imaging." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/12005.

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7

Auksorius, Egidijus. "Multidimensional fluorescence imaging and super-resolution exploiting ultrafast laser and supercontinuum technology." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4201.

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This thesis centres on the development of multidimensional fluorescence imaging tools, with a particular emphasis on fluorescence lifetime imaging (FLIM) microscopy for application to biological research. The key aspects of this thesis are the development and application of tunable supercontinuum excitation sources based on supercontinuum generation in microstructured optical fibres and the development of stimulated emission depletion (STED) microscope capable of fluorescence lifetime imaging beyond the diffraction limit. The utility of FLIM for biological research is illustrated by examples of experimental studies of the molecular structure of sarcomeres in muscle fibres and of signalling at the immune synapse. The application of microstructured optical fibre to provide tunable supercontinuum excitation source for a range of FLIM microscopes is presented, including wide-field, Nipkow disk confocal and hyper-spectral line scanning FLIM microscopes. For the latter, a detailed description is provided of the supercontinuum source and semi-confocal line-scanning microscope configuration that realised multidimensional fluorescence imaging, resolving fluorescence images with respect to excitation and emission wavelength, fluorescence lifetime and three spatial dimensions. This included the first biological application of a fibre laser-pumped supercontinuum exploiting a tapered microstructured optical fibre that was able to generate a spectrally broad output extending to ~ 350 nm in the ultraviolet. The application of supercontinuum generation to the first super-resolved FLIM microscope is then described. This novel microscope exploited the concept of STED with a femtosecond mode-locked Ti:Sapphire laser providing a tunable excitation beam by pumping microstructured optical fibre for supercontinuum generation and directly providing the (longer wavelength) STED beam. This STED microscope was implemented in a commercial scanning confocal microscope to provide compatibility with standard biological imaging, and exploited digital holography using a spatial light modulator (SLM) to provide the appropriate phase manipulation for shaping the STED beam profile and to compensate for aberrations. The STED microscope was shown to be capable of recording super resolution in both the lateral and axial planes, according to the settings of the SLM.

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Lanigan, Peter Michael Pinto. "Applications of confocal and multiphoton laser scanning microscopes to multi-dimensional fluorescence imaging." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439847.

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9

Sasaki, K., T. Wakasaki, S. Matsui, and K. Kadota. "Distributions of C_2 and C_3 radical densities in laser-ablation carbon plumes measured by laser-induced fluorescence imaging spectroscopy." American Institute of Physics, 2002. http://hdl.handle.net/2237/7043.

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10

Berckmuller, Martin. "A study of mixture formation in a lean burn research engine using laser fluorescence imaging." Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/9933.

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Lean burn in spark-ignition engines offers a significant efficiency advantage compared with stoichiometric operation. The lean operation is restricted by increasing cyclic fluctuation in torque. In order to make use of the efficiency advantage and meet the mandatory emission standards the lean operation limit has to be further extended. This requires particular control of the mixing of fuel and air. To study the effect of mixture formation on cyclic variability and to provide quantitative information on the mixing of air and fuel planar laser-induced fluorescence (PLIF) was developed and applied to an operating SI engine. The method is based on imaging the fluorescence of a fluorescent marker (3-pentanone) mixed with the fuel (iso-octane). 3-pentanone was found to have similar vaporisation characteristics to those of iso-octane as well as low absorption and suitable spectral properties. The technique was applied to an one-cylinder SI engine with a cylinder head configuration based on the Honda VTEC-E lean burn system. The mixture formation process during the inlet and compression stroke could be described by measuring the average fuel concentration in four planes, between 0.7 and 15.2 mm below the spark plug, in a section of the cylinder orthogonal to the cylinder axis. The results showed that for 4-valve pent-roof cylinder head systems with swirl inlet flows, fuel impinging on the cylinder wall opposite to the inlet valves has a major influence on the mixture formation process. In order to quantify the cyclic variability in the mixture formation process and its contribution to cyclic variability in combustion the fuel concentration in a plane near the spark plug was measured on a large number of cycles. It could be shown, that the fuel concentration in a small region close to the spark plug has a dominating effect on the subsequent pressure development for lean mixtures. Variations in the mixture concentration in the vicinity of the spark plug contribute significantly to cyclic variations in combustion. In order to address the issue of nonuniformity in residual gas concentration prior to ignition a laser induced fluorescence method was developed to measure nitric oxide (NO) concentrations in the unburned charge in the same one-cylinder research engine. Measurements of average and instantaneous NO concentrations revealed, that the residual gas is not homogeneously mixed with the air and that significant cyclic variations in the local residual gas concentration exist.

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11

Berkmuller, Martin. "A study of mixture formation in a lean burn research engine using laser fluorescence imaging." Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/10431.

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Lean burn in spark-ignition engines offers a significant efficiency advantage compared with stoichiometric operation. The lean operation is restricted by increasing cyclic fluctuation in torque. In order to make use of the efficiency advantage and meet the mandatory emission standards the lean operation limit has to be further extended. This requires particular control of the mixing of fuel and air. To study the effect of mixture formation on cyclic variability and to provide quantitative information on the mixing of air and fuel planar laser-induced fluorescence (PLIF) was developed and applied to an operating SI engine. The method is based on imaging the fluorescence of a fluorescent marker (3-pentanone) mixed with the fuel (iso-octane). 3-pentanone was found to have similar vaporisation characteristics to those of iso-octane as well as low absorption and suitable spectral properties. The technique was applied to an one-cylinder SI engine with a cylinder head configuration based on the Honda VTEC-E lean burn system. The mixture formation process during the inlet and compression stroke could be described by measuring the average fuel concentration in four planes, between 0.7 and 15.2 mm below the spark plug, in a section of the cylinder orthogonal to the cylinder axis. The results showed that for 4-valve pent-roof cylinder head systems with swirl inlet flows, fuel impinging on the cylinder wall opposite to the inlet valves has a major influence on the mixture formation process. In order to quantify the cyclic variability in the mixture formation process and its contribution to cyclic variability in combustion the fuel concentration in a plane near the spark plug was measured on a large number of cycles. It could be shown, that the fuel concentration in a small region close to the spark plug has a dominating effect on the subsequent pressure development for lean mixtures. Variations in the mixture concentration in the vicinity of the spark plug contribute significantly to cyclic variations in combustion. In order to address the issue of no uniformity in residual gas concentration prior to ignition a laser induced fluorescence method was developed to measure nitric oxide (NO) concentrations in the unburned charge in the same one-cylinder research engine. Measurements of average and instantaneous NO concentrations revealed, that the residual gas is not homogeneously mixed with the air and that significant cyclic variations in the local residual gas concentration exist.

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12

Fuller, Joseph P. "High-frame-rate planar laser-induced fluorescence imaging of diesel sprays using pulse burst diagnostics." [Ames, Iowa : Iowa State University], 2009.

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13

Yamamoto, Ryuta. "A Quantum Gas Microscope of Two-electron Atoms with Fluorescence and Faraday Imaging." Kyoto University, 2016. http://hdl.handle.net/2433/217727.

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14

Staufer, Theresa Maria [Verfasser], and Florian [Akademischer Betreuer] Grüner. "X-Ray Fluorescence Imaging with a Laser-Driven X-Ray Source / Theresa Maria Staufer ; Betreuer: Florian Grüner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1217408878/34.

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15

Moses, Lance. "Fluorescence Imaging of Analyte Profiles in an Inductively Coupled Plasma with Laser Ablation as a Sample Introduction Source." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/4367.

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Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has risen to among the top tier techniques for the direct analysis of solid samples. However, significant problems remain that must be solved to achieve the full analytical potential of LA-ICP-MS. Inefficient conversion of aerosol to ions within the ICP or transmission through the MS interface may decrease precision, sensitivity, and/or accuracy. Although fundamental mechanisms that govern ion production and transmission have been studied extensively in solution-nebulization (SN) ICP-MS instruments, significant gaps in our understanding remain. Furthermore, it is unclear to what extent differences between the aerosols generated during SN and LA influence either ion production or transmission. In this work, I initially investigated differences in the spatial distributions of Ca, Ba, and Sc ions generated by LA and SN using high-resolution LIF imaging. Ions formed from aerosol generated by LA at low fluence were distributed over much greater axial and narrower radial distances than SN aerosol. Additionally, I investigated the effects of solvent, laser fluence, and ablation atmosphere (He vs Ar) on ion distributions in the ICP. Unlike solvent, changing laser fluence and ablation atmosphere produced considerable changes in the ion signal intensity and spatial distribution during LA. At greater laser fluence, the radial distance over which ions were distributed dramatically increased. Surprisingly, when helium was mixed with argon as carrier gas, ion signals decreased. Many of these effects were assumed to be related to changes in the number and size of particles generated during LA. In a follow-up study, relative contributions to ion densities in the ICP from particles of different sizes were investigated. LIF images were recorded while filtering particles above a threshold size on-line. Micron-sized particles contributed the majority of ions formed in the ICP. For Ba, Ca, and Sc, differences in the axial position where nanometer- and micron-sized particles vaporized were 2, 1, and less than 1 mm, respectively. I also performed experiments to identify changes in the ion signal related to changing ablation conditions vs. changing ICP conditions associated with helium additions to the carrier gas. LIF images were recorded during different combinations of He/Ar added upstream and/or downstream of the ablation cell. Changes in the ion signal during ablation in helium vs argon did not always match expectations based on changes in particle numbers and sizes measured with SEM. The results force re-examination of some of the fundamental assumptions about the effect of carrier gas composition on the performance of LA-ICP-MS. The research described in this dissertation provides valuable insight into fundamental aspects of key ICP processes related to LA generated aerosol.

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Brümmer, Theresa [Verfasser], and Florian [Akademischer Betreuer] Grüner. "Design Study of a Laser-Driven X-ray Source for Medical Fluorescence Imaging / Theresa Brümmer ; Betreuer: Florian Grüner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2018. http://d-nb.info/1160036063/34.

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17

Brümmer, T. [Verfasser], and Florian [Akademischer Betreuer] Grüner. "Design Study of a Laser-Driven X-ray Source for Medical Fluorescence Imaging / Theresa Brümmer ; Betreuer: Florian Grüner." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2018. http://nbn-resolving.de/urn:nbn:de:gbv:18-91354.

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18

Liu, Quan. "Planar laser induced fluorescence imaging and analysis with ethanol blended fuels in a direct injection spark ignition engine." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/14786.

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The currently reported thesis was concerned with visualisation of the charge homogeneity and cyclic variations within the planar fuel field near the spark plug in an optical spark ignition engine fitted with an outwardly opening central direct fuel injector. Specifically, the project examined the effects of fuel type and injection settings, with the overall view to understanding some of the key mechanisms previously identified as leading to particulate formation in such engines. The three fuels studied included a baseline iso-octane, which was directly compared to two gasoline fuels containing 10% (E10) and 85% (E85) volume of ethanol respectively. The engine was a bespoke single cylinder with Bowditch style optical access through a flat piston crown. Charge stratification was studied over a wide spectrum of injection timings using the Planar Laser Induced Fluorescence (PLIF) technique, with additional variation in charge temperature due to injection also estimated when viable using a two-line PLIF approach. Overall, both gasoline-ethanol fuels generally exhibited a higher degree of stratification, albeit at least partly alleviated with elevated rail pressures. Under both warm and cold liner conditions the E10 fuel showed clear evidence of fuel droplets persisting up until ignition. Interestingly, with late injection timing the repeatability of the injection was superior (statistically) with higher ethanol content in the fuel, which may have been associated with the higher charge temperatures aiding control of the evaporation of the main mass of alcohol. The findings were corroborated by undertaking a comprehensive study of the influence of varying fuel type and injection settings on thermodynamic performance and engine-out emissions during firing operation, with additional gas exchange effects also influencing the optimum fuel injection timings.

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19

Kranz, Patrick [Verfasser], and Sebastian [Akademischer Betreuer] Kaiser. "Imaging of mixing processes in spark-ignition engines via quantitative laser-induced fluorescence / Patrick Kranz ; Betreuer: Sebastian Kaiser." Duisburg, 2020. http://d-nb.info/1218465352/34.

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20

Bélisle, Jonathan. "Design and assembly of a multimodal nonlinear laser scanning microscope." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100765.

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The objective of this thesis is to present the fabrication of a multiphoton microscope and the underlying theory responsible for its proper functioning. A basic introduction to nonlinear optics will give the necessary knowledge to the reader to understand the optical effects involved. Femtosecond laser pulses will be presented and characterized. Each part of the microscope, their integration and the design of the microscope will be discussed. The basic concepts of laser scanning microscopy are also required to explain the design of the scanning optics. Fast scanning problems and their solutions are also briefly viewed. As a working proof, the first images taken with the microscope will be presented. Fluorescent beads, rat tail tendon, gold nanoparticles and pollen grain images using various nonlinear effects will be shown and discussed.

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Edmund, Alisa Jane. "Laser-Induced Fluorescence Imaging of Calcium and Barium Ion Beams in the Second Vacuum Stage of a Commercial Inductively Coupled Plasma Mass Spectrometer." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4135.

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Inductively coupled plasma-mass spectrometers (ICP-MS) have become the workhorses of many analytical labs over the past few decades. Despite the instruments' high sensitivities and low detection limits there is still a demand for improvements in several aspects of their performance. One area of improvement is in the understanding of "space charge effects" Space charge effects are classified as problems associated with the ion beam. Problems are created when the mutual repulsions of the ions make consistent focusing of the ion beam difficult. This is particularly problematic with samples containing a low concentration analyte contained within a high salt solution matrix, resulting in lower instrument sensitivity and inaccurate results. The research presented here used laser-induced fluorescence (LIF) imaging to characterize the ion beam as it enters the mass analyzer of a commercial ICP-MS. To perform the LIF imaging a laser system with two ring cavities was constructed to frequency double a CW titanium-sapphire laser to the calcium ion transition at 393.4 nm or to the barium ion transition at 455.4 nm. Ion beam images for both elements were taken under different instrument modes and matrix compositions. The same trends in shift and distortion of the barium ion beam with the addition of a lead matrix was observed as in previous experiments with calcium. A shift in the focal point of the ion beams of both elements was also observed in normal sensitivity mode and with the instrument's collisional reaction interface (CRI). This work indicates that a shift in beam focusing is responsible for the change in ion transmission due to changes in matrix composition and instrument modes.

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22

Vilmart, Gautier. "Détection de vapeurs d'atomes métalliques par fluorescence induite par laser (LIF) : application à la propulsion solide." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS523/document.

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Cette thèse porte sur la méthode de Fluorescence Induite par Laser (LIF) à haute cadence développée sur deux atomes métalliques (Al et Fe) utilisés comme traceurs fluorescents dans les flammes de propergols solides où ils sont naturellement présents. Deux expériences d’évaporation de l’aluminium sont mises en œuvre pour mettre au point la technique dans des conditions contrôlées sur une large gamme de pressions et températures. Un modèle théorique du processus de fluorescence appliqué à ces deux atomes est élaboré pour calculer les taux de quenching du signal avec la pression et la température. Les données collisionnelles qui sont inconnues sont prédéterminées théoriquement pour Fe et expérimentalement pour Al. Les coefficients de transferts d’énergie et d’élargissements spectraux par collisions de l’atome Al sont déterminés expérimentalement en environnement d’azote pur. Une étude du comportement du signal de Al avec l’énergie laser est effectuée pour mesurer les seuils de saturation avec les gaz N₂, Ar et He en fonction de la pression. Le modèle permet de reproduire correctement les profils temporels et spectraux avec toutefois des approximations et des limitations qui sont explicitées. Une première application de l’imagerie LIF sur Al dans une flamme de propergol solide aluminisé (10 bar et 3000 K) permet de visualiser des gouttes d’aluminium réactives et observer leur évolution dans la flamme
During the PhD thesis, high-speed laser induced fluorescence (LIF) of two metallic atoms (Al and Fe) is presented, in order to use them as fluorescent markers in solid propellant flames, where they are naturally present. LIF measurements are first performed inside two different evaporation chambers used to generate aluminum vapors in controlled conditions over a broad pressure and temperature range. A theoretical model of the LIF process is elaborated and applied to both atoms in order to calculate the signal quenching rate as a function of pressure and temperature. Unavailable collisional data are determined theoretically for Fe and experimentally for Al. Energy transfer and collisional broadening coefficients are determined experimentally for the Al atom in pure nitrogen environment. Study of the signal level of Al as a function of laser intensity is undertaken to measure saturation thresholds in N₂, He and Ar as a function of pressure. The model is used to properly reproduce the temporal and spectral profiles, though some approximations and limitations remain. A first application of high-speed LIF imaging to the measurement of aluminum in a solid propellant flame (10 bar , 3000 K) is demonstrated. It allows us to clearly visualize reactive aluminum droplets in the flame and to follow their evolution in the flame

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23

Davoudi, Henrik. "Characterisation of mixture preparation in lean premixed prevaporised combustor modules by planar laser fluorescence imaging and computational fluid dynamics modelling." Thesis, Cranfield University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393697.

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24

Wall, Richard Andrew. "Multi-Modality Endoscopic Imaging for the Detection of Colorectal Cancer." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301761.

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Optical coherence tomography (OCT) is an imaging method that is considered the optical analog to ultrasound, using the technique of optical interferometry to construct two-dimensional depth-resolved images of tissue microstructure. With a resolution on the order of 10 μm and a penetration depth of 1-2 mm in highly scattering tissue, fiber optics-coupled OCT is an ideal modality for the inspection of the mouse colon with its miniaturization capabilities. In the present study, the complementary modalities laser-induced fluorescence (LIF), which offers information on the biochemical makeup of the tissue, and surface magnifying chromoendoscopy, which offers high contrast surface visualization, are combined with OCT in endoscopic imaging systems for the greater specificity and sensitivity in the differentiation between normal and neoplastic tissue, and for the visualization of biomarkers which are indicative of early events in colorectal carcinogenesis. Oblique incidence reflectometry (OIR) also offers advantages, allowing the calculation of bulk tissue optical properties for use as a diagnostic tool. The study was broken up into three specific sections. First, a dual-modality OCTLIF imaging system was designed, capable of focusing light over 325-1300 nm using a reflective distal optics design. A dual-modality fluorescence-based SMC-OCT system was then designed and constructed, capable of resolving the stained mucosal crypt structure of the in vivo mouse colon. The SMC-OCT instrument's OIR capabilities were then modeled, as a modified version of the probe was used measure tissue scattering and absorption coefficients.

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Palmer, Johannes [Verfasser], Reinhold [Akademischer Betreuer] Kneer, and Frank [Akademischer Betreuer] Beyrau. "A laser-induced fluorescence technique for temperature imaging of micro-droplets avoiding morphology dependent resonances / Johannes Palmer ; Reinhold Kneer, Frank Beyrau." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/121778974X/34.

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Watson, Jeffrey R., Summer Garland, and Marek Romanowski. "Intraoperative visualization of plasmon resonant liposomes using augmented microscopy." SPIE-INT SOC OPTICAL ENGINEERING, 2017. http://hdl.handle.net/10150/625390.

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Plasmon resonance associated with nanoparticles of gold can enable photothermal ablation of tissues or controlled drug release with exquisite temporal and spatial control. These technologies may support many applications of precision medicine. However, clinical implementations of these technologies will require new methods of intraoperative imaging and guidance. Near-infrared laser surgery is a prime example that relies on improved image guidance. Here we set forth applications of augmented microscopy in guiding surgical procedures employing plasmon resonant gold-coated liposomes. Absorption of near-infrared laser light is the first step in activation of various diagnostic and therapeutic functions of these novel functional nanoparticles. Therefore, we demonstrate examples of near-infrared visualization of the laser beam and gold-coated liposomes. The augmented microscope proves to be a promisingimage guidance platform for a range of image-guided medical procedures.

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27

Dunand, Pierre. "Étude de l'impact de goutte sur une paroi chaude en régime de Leidenfrost." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0166/document.

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Les impacts de gouttes sur paroi chaude sont présents dans de multiples domaines, tels que l'injection de diesel sous forme de spray dans des moteurs à combustions internes, ou le traitement thermiques de l'acier dans le domaine de la sidérurgie. L'étude de l'interactions goutte/paroi permet de mieux comprendre les phénomènes thermiques mis en jeu, et ainsi d'aboutir à des économies d'énergies et d'eau. De nombreux travaux portent sur cette thématique, mais ils présentent des résultats divergents et uniquement basés sur l'étude de la paroi chaude. Cette thèse a pour but d'apporter des mesures expérimentales sur les caractéristiques inconnues en étudiant les gouttes. Pour cela, un dispositif expérimental a été mis au point afin de mener à bien l'ensemble des mesures souhaitées. Les diverses techniques de mesures de température utilisées sont présentées, et une attention plus particulière a été portée sur le développement de la technique de fluorescence induite par plan laser qui permet d'accéder au champ de température des gouttes durant leur impact. Cette méthode, combinée à une technique de thermographie par caméra infrarouge couplée à un modèle de conduction inverse, permet d'extraire les paramètres concernant l'aspect thermique, et de déterminer de nouvelles caractéristiques inédites, telles que l'échauffement des gouttes, l'évaporation relative de celles-ci ou encore l'efficacité de refroidissement. Les parts respectives jouées par la chaleur sensible et l'évaporation des gouttes sont tirées de cette dernière. Enfin, l'aspect dynamique est également abordé aboutissant au développement d'une technique d'ombroscopie rapide. Cette dernière a permis, grâce à la combinaison de mesures de diamètres précises et d'une fréquence d'acquisition élevée, d'extraire les paramètres dynamiques de l'impact tels que la vitesse et taille des gouttes, ou d'autres paramètres relatif au type d'impact rencontrés à l'aide d'un algorithme de suivi de particules développé durant la thèse
The droplet impact onto a heated wall interaction can be found in mutiples fields, such as internal combustion engines or the steel industry, specially in the thermal treatment of the steel where high energy dissipation rate is required. The study of this interaction should grant a better understanding of this phenomena, and thus, allow the enhancement of these processes and reduce the energy and water consumption. Several studies have already been carried out on this subjet but a great majority of them, whose results present great divergence, only consider the heated wall, neglecting the outgoing of the droplet. This thesis put the emphasis on the liquid phase where currently no data exist to our knowledge, with the help of multiples experimental technics that have been developped. A general experimental setup has been made in order to make all the wanted measurements. The measurement techniques used in this study are first presented, to begin with the planar laser induced fluorescence, which allow us to know the droplet temperature during the impact. Used with an infrared thermography technique coupled with an inverse conduction model, it is possible to extract some important parameter regarding the thermal aspect, such as the droplet heating, the relative evaporation ratio or the cooling efficiency. This latter can be written as the sum of the two major contributions of the cooling: the sensible heat and the evaporation of the droplet. Finally, a high speed shadow imagery technique is presented. It has been developped in order to study the dynamic aspect of the droplet impact. This technique can determine several dynamic parameters such as the droplet speed and diameter, or other parameter regarding the type of impact encountered

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Guiberti, Thibault. "Analyse de la topologie des flammes prémélangées swirlées confinées." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2015. http://www.theses.fr/2015ECAP0014/document.

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Ce travail porte sur la stabilisation de flammes prémélangées et swirlées de mélanges combustibles méthane/hydrogène/air avec différents taux de dilution d’azote et de dioxyde de carbone. Une tige centrale permet de stabiliser des flammes pour de faibles nombres de swirl. Le sommet de la flamme interagît éventuellement avec les parois de la chambre de combustion. L’objectif ces travaux est d’améliorer la connaissance des mécanismes qui gouvernent la stabilisation et la topologie de ces flammes. Ces travaux démontrent que le nombre de swirl, la composition du mélange combustible, la géométrie de la chambre de combustion ainsi que les conditions aux limites thermiques ont une grande influence sur la forme prise par la flamme. Le dispositif expérimental permet de modifier la forme et la taille de la chambre de combustion, le diamètre du tube d’injection et le nombre de swirl. Des conditions opératoires propices aux transitions de forme de flamme sont ensuite étudiées pour différentes configurations de brûleur. Une caractérisation expérimentale fouillée d’un point de fonctionnement est réalisée grâce à la Fluorescence Induite par Laser sur le radical Hydroxyle (OH-PLIF), la Vélocimétrie par Images de Particules (PIV) et la Phosphorescence Induite par Laser de phosphores sensibles à la température (LIP). Une base de donnée de l’écoulement et des conditions aux limites associées est obtenue sans et avec combustion. Les mécanismes qui contrôlent les transitions de formes de flamme sont ensuite analysés lorsque la flamme interagit avec les parois de la chambre de combustion. L’influence de la composition du mélange combustible, de la vitesse débitante et du nombre de swirl est caractérisée et il est démontré que la transition d’une flamme en V vers une flamme en M est déclenchée par un retour de flamme dans la couche limite le long d’une des parois latérales de la chambre de combustion. Les nombres sans dimension contrôlant ces transitions sont identifiés et un modèle de prévision de la forme de ces flammes est développé. La physique déterminant les transitions de forme de flammes est différente lorsque celles-ci n’interagissent pas avec les parois de la chambre de combustion. En utilisant le signal de chimiluminescence OH* et la OH-PLIF, il est montré que la teneur en hydrogène dans le combustible a une grande influence sur la forme de flamme. L’utilisation de la LIP et de thermocouples a également permis de montrer que les conditions aux limites thermiques jouent un rôle prépondérant sur la forme de flamme. Les effets combinés de l’étirement et des pertes thermiques sont examinés par l’utilisation conjointe de la PIV et de la OH-PLIF. Il est montré que les limites d’extinction de flammes pauvres prémélangées sont réduites par les pertes thermiques et que la transition d’une flamme en M vers une flamme en V est consécutive à l’extinction du front de flamme situé dans la couche de cisaillement externe du jet soumis à un étirement trop important. Ces expériences sont complétées par une analyse de la dynamique de ces flammes. Des modulations de la vitesse débitante à basse fréquence et à haute amplitude modifient la forme de flamme. La stabilisation de flammes CH4/H2/air diluées par du N2 ou du CO2 est finalement examinée. La zone de recirculation produite par la tige centrale permet d’alimenter la base de la flamme avec des gaz brûlés chauds et de stabiliser des flammes fortement diluées. Augmenter la fraction molaire de diluant dans le combustible réduit l’intensité de lumière émise par le radical OH*. Il est également montré que la composition du diluant a un impact sur le champ de température des gaz brûlés et des surfaces de la chambre de combustion. La dilution par du CO2 augmente les pertes thermiques par rayonnement des gaz brûlés. Cela réduit l’efficacité de la chambre de combustion équipée de quatre parois transparentes. [...]
This work deals with the stabilization of premixed turbulent swirling flames of methane/hydrogen/air combustible mixtures with different dilution rates of nitrogen and carbon dioxide. A central bluff body helps stabilizing the flames at low swirl numbers. The flame tip eventually impinges the combustor peripheral wall. The general objective is to gain understanding of the mechanisms governing the stabilization and the topology of these flames. It is found that the swirl number, the combustible mixture composition, the geometry of the combustor, and the thermal boundary conditions have a strong impact on the shape taken by these flames. The experimental setup used to characterize flames topologies is first described. Flames prone to topology bifurcations are selected and are studied for different arrangement of the combustor when the combustion chamber shape and size, the injection tube diameter, and swirl number are varied. One operating condition is fully characterized under non-reactive and reactive conditions using Planar Hydroxyl Laser Induced Fluorescence (OH-PLIF), Particle Imaging Velocimetry (PIV), and Laser Induced Phosphorescence of thermographic phosphors (LIP) to generate a detailed database of the flow and the corresponding boundary conditions. An analysis is then conducted to understand the mechanisms controlling shape bifurcations when the flame interacts with the combustor peripheral wall. Effects of the combustible mixture composition, the bulk flow velocity, and the swirl number are analyzed. It is shown that the transition from a V to an M flame is triggered by a flashback of the V flame tip in the boundary layer of the combustor peripheral wall. Dimensionless numbers controlling these transitions are identified and a simplified model is developed to help the prediction of the flame shapes. The physics of these shape bifurcations differs when the flame does not interact with the combustor wall. The large influence of the hydrogen enrichment in the fuel on the flame shape is analyzed using flame chemiluminescence and OH-PLIF. LIP and thermocouple measurements demonstrate that the thermal boundary conditions still have a strong impact on the flame topology. The combined effects of strain and heat losses are investigated using joint OH-PLIF and PIV experiments. It is shown that flammability limits of premixed flames are reduced due to heat losses and the transitions from M to V shaped flames is consecutive to localized extinctions of flame front elements located in the outer shear layer of the jet flow that are submitted to large strain rates. These experiments are completed by an analysis of the dynamics of methane/hydrogen/air flames. It is shown that low frequency and high amplitude velocity modulations generated by a loudspeaker alter the shape taken by these flames. The stabilization of methane/hydrogen/air flames diluted by nitrogen and carbon dioxide is finally examined. It was possible to stabilize swirled flames featuring important dilution rates due to the presence of the bluff body, installed on the axis of the injection tube. The recirculation zone behind this element supplies hot burnt gases to the flame anchoring point. Using OH* chemiluminescence imaging, it is shown than increasing the molar fraction of diluent in the fuel reduces the light emission from excited OH* radicals. The influence of dilution on the flame chemistry is emphasized with experiments conducted at a fixed thermal power and fixed adiabatic flame temperature. It is also demonstrated that the composition of the diluent has a strong influence on the temperature field of the burnt gases and of the combustor wall surfaces. Dilution with carbon dioxide increases radiative heat losses from the burnt gases in comparison to dilution with nitrogen. This penalizes the combustor efficiency equipped with four transparent quartz walls. [...]

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Cosimi, Julien. "Caractérisations d'un jet de plasma froid d'hélium à pression atmosphérique." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30136.

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Les jets de plasma froid à la pression atmosphérique connaissent un réel engouement dans de nombreux domaines du biomédical depuis la dernière décennie. Dans les différentes applications de ces jets, le plasma généré est amené à interagir avec de nombreux types de surfaces. Les jets de plasma ont une influence sur les surfaces traitées, mais il est maintenant connu que les surfaces traitées influencent également le plasma en fonction de leurs caractéristiques. Le travail mené dans cette thèse a donc pour but de caractériser un jet de plasma froid d'hélium à la pression atmosphérique en contact avec trois types de surfaces (diélectrique, métallique et eau ultrapure) au moyen de différents diagnostics électriques et optiques afin de comprendre l'influence de la nature des surfaces sur les propriétés physiques du plasma et les espèces chimiques générées. La première partie de cette thèse s'intéresse à l'étude de l'influence des surfaces sur le jet de plasma. Différents paramètres sont étudiés, tels que la nature de la surface exposée, le débit de gaz, la distance entre la sortie du dispositif et la surface exposée ou encore la composition du gaz plasmagène. Pour ce faire, nous avons utilisé dans un premier temps l'imagerie Schlieren afin de suivre le flux d'hélium en sortie du dispositif en présence ou non de la décharge. La spectroscopie d'émission a été utilisée pour déterminer les espèces émissives générées par le plasma. L'imagerie rapide nous a permis de suivre la génération et la propagation de la décharge et la distribution de certaines espèces excitées dans le jet avec l'aide de filtres interférentiels passe-bandes. Une cible diélectrique entraîne un étalement de l'onde d'ionisation sur sa surface et une cible conductrice entraîne la formation d'un canal de conduction. L'évolution de la densité d'espèces excitées (OH*, N2*, He* et O*) augmente avec la permittivité relative de la surface traitée. Le rôle joué par les espèces actives générées par les jets de plasma est fondamental dans la cinétique et la chimie des mécanismes liés aux procédés plasma. La seconde étape de la thèse porte donc sur l'évaluation spatiale et temporelle des densités du radical hydroxyle OH, une espèce jouant un rôle majeur dans de nombreux mécanismes. La cartographie spatiale et l'évolution temporelle des densités absolues et relatives de OH ont été obtenues au moyen de diagnostics lasers LIF et PLIF. La densité de OH générée augmente avec la permittivité relative de la surface traitée. On constate que les radicaux OH restent présents dans le canal d'hélium entre deux décharges consécutives (plusieurs dizaines de microsecondes). Enfin, nous nous sommes intéressés à la production d'espèces réactives à longue durée de vie dans l'eau ultrapure traitée par plasma. L'influence de différents paramètres sur la concentration d'espèces dans l'eau traitée a été étudiée dans le but d'optimiser la production de ces espèces. Dans nos conditions expérimentales, la mise à la masse de l'eau ultrapure lors du traitement permet l'augmentation de la concentration de H2O2. Par ailleurs, la mise à la masse induit une diminution la concentration de NO2-
Cold atmospheric pressure plasma jets are a subject of great interest in many biomedical fields for the past decade. In the various applications of these jets, the plasma generated can interact with many types of surfaces. Plasma jets influence the treated surfaces, but it is now well known that the treated surface also influences the plasma according to their characteristics. The work carried out in this thesis therefore aims to characterize a cold helium atmospheric pressure plasma jet in contact with three surfaces (dielectric, metallic and ultrapure water) by means of different electrical and optical diagnostics in order to understand the influence of the nature of the surfaces on the physical properties of the plasma and the chemical species generated. The first part of this thesis is focused on the study of the influence of surfaces on the plasma jet. Different parameters are studied, such as the nature of treated surfaces, the gas flow, the distance between the outlet of the device and the surface or the composition of the injected gas. For this purpose, helium flow at the outlet of the device is followed by Schlieren imagery with and without the discharge. Emission spectroscopy is used to determine the emissive species generated by the plasma. ICCD imagery is employed to follow the generation and the propagation of the discharge and the distribution of several excited species in the jet by using band-pass interference filters. A dielectric target causes the ionization wave to spread over its surface and a conductive target leads to the formation of a conduction channel. The evolution of excited species densities (OH*, N2*, He* and O*) increases with the relative permittivity of the treated surface. As well known, active species generated by plasma jets play a fundamental role in the kinetics and the chemistry of the mechanisms linked to plasma processes. The second part of the present work therefore relates to the spatial and temporal evaluation of the densities of the hydroxyl radical OH which plays a major role in many cellular mechanisms. The spatial mapping and the temporal evolution of the absolute and relative densities of OH are obtained by LIF and PLIF laser diagnostics. The density of OH generated increases with the electrical conductivity of the treated surface. It can be noted that the OH molecules remain present in the helium channel between two consecutive discharges (several tens of microseconds). Finally, we focus on the production of chemical species in ultrapure water treated with plasma. The influence of different parameters on the concentration of species in the treated water has been studied to optimize the production of chemical species. In experimental conditions, grounding the ultrapure water during treatment increases the concentration of H2O2. Furthermore, the grounding induces a decrease in the NO2- concentration

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30

Tawidian, Hagop-Jack. "Formation et comportement de nanoparticules dans un plasma : instabilités dans les plasmas poudreux." Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2033/document.

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L'objectif de cette thèse est l'étude de la formation de nanoparticules carbonées dans un plasma basse pression. Les poussières sont créées par pulvérisation d'une couche de polymère déposée sur l'électrode d'une décharge radio fréquence à couplage capacitif. La présence des poudres perturbe et modifie les propriétés du plasma. La croissance des poudres peut notamment déclencher des instabilités basse fréquence qui évoluent avec la taille et la densité des poudres. Au centre du plasma, une région sans poudre, appelée void, est souvent observée. Cette région se caractérise en particulier par une forte luminosité. Différents diagnostics (mesures électriques, imagerie vidéo rapide, Fluorescence Induite par Laser) sont utilisées afin d'analyser ces différents comportements résultant des interactions entre le plasma et les poussières. L'analyse approfondie des instabilités a permis de mettre en évidence plusieurs régimes et d'extraire leurs principales caractéristiques comme leur durée et l'évolution de leurs fréquences. Ces instabilités se traduisent par la formation de petites "boules" de plasma qui se déplacent et interagissent au sein de celui-ci. Des phénomènes particulièrement surprenants de fusion et de division de ces boules ont été mis en évidence. Concernant le void, nos travaux ont confirmé la forte excitation présente dans cette zone. Dans la dernière partie de la thèse, la dissociation de l'aluminium triisopropoxide(ATI) est étudiée dans un plasma à l'aide de la Spectroscopie infrarouge à Transformée de Fourier. Ce diagnostic nous a permis de mettre en évidence l'évolution de la densité d'ATI en fonction des paramètres de la décharge. Nous avons également quantifié les différents composants hydrocarbonés formés par polymérisation
The objective of this thesis is to study the formation of carbonaceous nanoparticles in a low pressure plasma. Dust particles are created by sputtering a polymer layer deposited on the bottom electrode of a capacitively coupled radio-frequency discharge. The presence of dust particles disturbs and changes the plasma properties. The growth of dust particles can trigger low frequency instabilities that evolve with the dust particle size and density. In the center of the discharge, the void, a dust-free region, is observed. It is characterized by an enhanced luminosity. Different diagnostics (electrical measurements, high speed imaging, Laser Induced Fluorescence) are used in order to understand these different behaviors resulting from plasma-dust particle interactions. Dust particle growth instabilities are investigated showing the existence of different instability regimes. Their main characteristics are extracted such as their duration and their evolution frequency. These instabilities are characterized by the formation of small plasma spheroids moving and interacting in the discharge. Several interesting phenomena are evidenced such as the merging and splitting of these plasma spheroids. Concerning the void, our investigations confirmed the high excitation occurring in this region. In the last part of the thesis, the dissociation of aluminium triisopropoxide (ATI) is studied in a plasma using Fourier Transform InfraRed spectroscopy. Thanks to this diagnostic, the evolution of ATI density has been studied as a function of the discharge parameters. We have also quantified the different hydrocarbon compounds formed by polymerization

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31

Lee, Woei Ming. "Optical trapping : optical interferometric metrology and nanophotonics." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/882.

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32

Dowling, Keith. "Application of ultrafast lasers to fluorescence lifetime imaging." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313763.

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Thompson, James Russell. "Imaging the assembly of the Staphylococcal pore-forming toxin alpha-Hemolysin." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:e320004a-6118-4dac-af2a-eca6e90be7ac.

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Alpha-hemolysin is a pore-forming toxin secreted by pathogenic Staphylococcus aureus. Its spontaneous oligomerization and assembly into a trans-bilayer beta-barrel pore is a model for the assembly of many other pore-forming toxins. It is studied here in vitro as a means to probe general membrane protein oligomerization and lipid bilayer insertion. This thesis details the results of experiments to develop and implement a novel in vitro lipid bilayer system, Droplet-on-Hydrogel Bilayers (DHBs) for the single-molecule imaging of alpha-hemolysin assembly. Chapter 2 describes the development of DHBs and their electrical characterization. Experiments show the detection of membrane channels in SDS-PAGE gels post-electrophoresis and DHBs use as a platform for nanopore stochastic sensing. Chapter 3 describes the engineering and characterization of fluorescently-labelled monomeric alpha-hemolysin for use in protein assembly imaging experiments described in Chapter 6. Chapter 4 describes the characterization of DHB lipid fluidity and suitability for single-molecule studies of membrane protein diffusion. In addition, a novel single-particle tracking algorithm is described. Chapter 5 describes experiments demonstrating simultaneous electrical and fluorescence measurements of alpha-hemolysin pores embedded within DHBs. The first multiple-pore stochastic sensing in a single-lipid bilayer is also described. Chapter 6 describes experiments studying the assembly of alpha-hemolysin monomers in DHBs. Results show that alpha-hemolysin assembles rapidly into its oligomeric state, with no detection of long-lived intermediate states.

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34

Bookjans, Eva M. "Relative number squeezing in a Spin-1 Bose-Einstein condensate." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37148.

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The quantum properties of matter waves, in particular quantum correlations and entanglement are an important frontier in atom optics with applications in quantum metrology and quantum information. In this thesis, we report the first observation of sub-Poissonian fluctuations in the magnetization of a spinor 87Rb condensate. The fluctuations in the magnetization are reduced up to 10 dB below the classical shot noise limit. This relative number squeezing is indicative of the predicted pair-correlations in a spinor condensate and lay the foundation for future experiments involving spin-squeezing and entanglement measurements. We have investigated the limits of the imaging techniques used in our lab, absorption and fluorescence imaging, and have developed the capability to measure atoms numbers with an uncertainly < 10 atoms. Condensates as small as ≈ 10 atoms were imaged and the measured fluctuations agree well with the theoretical predictions. Furthermore, we implement a reliable calibration method of our imaging system based on quantum projection noise measurements. We have resolved the individual lattice sites of a standing-wave potential created by a CO2 laser, which has a lattice spacing of 5.3 µm. Using microwaves, we site-selectively address and manipulate the condensate and therefore demonstrate the ability to perturb the lattice condensate of a local level. Interference between condensates in adjacent lattice sites and lattice sites separated by a lattice site are observed.

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Chadwick, Helen J. "Angular momentum polarisation effects in inelastic scattering." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:474b04fa-4f50-4618-88ab-c85878723f2a.

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In this thesis, a joint experimental and theoretical investigation of the vector properties that describe the inelastic scattering of a diatomic radical with an atomic collision partner is presented. A particular emphasis is placed on those correlations that include the final rotational angular momentum, j', of the radical. The depolarisation of both NO(A) and OH(A) brought about through collisions with krypton has been studied, providing a measure of the j-j' correlation, where j is the initial rotational angular momentum associated with the diatom. The total depolarisation cross- sections for both collisional disorientation and disalignment have been measured using quantum beat spectroscopy, and modelled theoretically using quasi-classical trajectory (QCT) calculations. The agreement between experiment and theory for NO(A)-Kr is excellent, but is not observed for OH(A)-Kr under thermal conditions. This has been attributed to the importance of electronic quenching in OH(A)-Kr. The depolarisation cross-sections have also been determined at a higher collision energy for OH(A)-Kr where electronic quenching is less significant, and the experimental results are in better agreement with those obtained theoretically. The NO(A)-Kr depolarisation cross-sections fall with increasing rotational quantum number, N, whereas for OH(A)-Kr, they exhibit less of an N dependence. This trend is mirrored in the elastic depolarisation cross-sections, which have also been determined experimentally for OH(A)-Kr. The significantly attractive and anisotropic nature of the OH(A)-Kr potential energy surface (PES) accounts for these observations. The j-j' correlation is extended to include the initial (relative) velocity (k) in a new theoretical treatment of the k-j-j' correlation. The formalism developed is used with the results from the QCT calculations for NO(A)-Kr and OH(A)-Kr to provide further insight into the mechanism of depolarisation in the two systems. Collisions of NO(A) with krypton do not cause significant depolarisation due to their impulsive nature, and the projection of j onto the kinematic apse is conserved. In contrast, collisions of OH(A) with krypton effectively randomise the direction of j, again showing the influence of the anisotropic and attractive nature of the PES. However, the projection of j onto the kinematic apse is still conserved. The inelastic scattering of NO(X) with argon and krypton has also been investigated, using a crossed molecular beam apparatus. The initial Λ-doublet state of the NO(X) was selected using hexapole focussing, and the products of the collision detected using velocity mapped ion imaging. The state to state differential cross-sections (equivalent to the k-k' correlation, where k' is the final relative velocity) have been measured for collisions which conserve the initial spin-orbit level of the NO(X) with krypton. The same parity dependent effects were seen as have been observed previously for NO(X)-Ar. The collision induced alignment (equivalent to the k-k'-j' correlation) of NO(X) as a result of scattering with argon has also been determined experimentally. The results can be explained classically by considering the conservation of the projection of j onto the kinematic apse.

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Do, Le Duy. "Relation entre l’annexine A6 et la phospholipase D1 pendant le processus d’exocytose dans les cellules PC12." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10160/document.

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L'exocytose régulée, est un processus qui permet la communication entre les cellules à travers la sécrétion des hormones et des neurotransmetteurs. Dans les neurones et les cellules neuroendocrines, l'exocytose est strictement contrôlée par des signaux extracellulaires tels que le potentiel trans-membranaire et la fixation des ligands sur des récepteurs. Des progrès substantiels ont été effectués afin de comprendre le mécanisme moléculaire de l'exocytose. Les composants majeurs de la machinerie de sécrétion ont été dévoilés. Maintenant, la question qui émerge concerne le rôle de la plateforme de protéines qui semble avoir une action coordonnée entre chaque protéine. Dans le cas de la famille des annexines, qui est bien connue pour son action dans l'exocytose, leurs modes d'interactions séquentielles ou concertées avec d'autres protéines ainsi que leurs effets régulateurs sur l'exocytose ne sont pas encore bien établis. Des résultats précédents indiquent que l'Annexine A6 (AnxA6) affecte l'homéostasie du calcium et la sécrétion de la dopamine à partir des cellules PC12, utilisées comme un modèle cellulaire de neurosécrétion (Podszywalow Bartnicka et al., 2010). Afin de déterminer l'effet inhibiteur de l'AnxA6 sur l'exocytose de la dopamine, nous cherchons des partenaires moléculaires de l'AnxA6 dans les cellules PC12. Nous faisons l'hypothèse que l'AnxA6 interagit avec la PLD1, une enzyme active dans l'étape de la fusion des vésicules avec la membrane plasmique. En utilisant la microscopie confocale et la microscopie à onde évanescente, nous avons trouvé que l'isoforme 1 de l'AnxA6 et la PLD1 sont tous les deux recrutés sur la surface des vésicules au cours de la stimulation des cellules PC12. AnxA6 inhibait l'activité de la PLD comme indiqué par notre méthode d'analyse enzymatique au moyen de la spectroscopie infrarouge. En conclusion, nous proposons que l'AnxA6 n'est pas seulement impliquée dans la réorganisation des membranes par ses capacités à se lier avec des phospholipides négativement chargés et avec le cholestérol, mais elle influence également l'activité de la PLD1, changeant la composition lipidique des membranes
The regulated exocytosis is a key process allowing cell-cell communication through the release of hormone and neurotransmitters. In neurons and neuroendocrine cells, it is strictly controlled by extracellular signal such as transmembrane potential and ligand bindings to receptors. Substantial progress has been made to understand the molecular mechanism of exocytosis. Major components of secretory machinery have been brought to light. Now the emergent question concerns the role of scaffolding proteins that are thought to coordinate the action of each other. In the case of annexin family well known to be involved in exocytosis, their modes of –sequential or concerted- interactions with other proteins, and their regulatory effects on exocytosis are not very well established. Previous findings indicated that Annexin A6 (AnxA6) affected calcium homeostasis and dopamine secretion from PC12 cells, used as cellular model of neurosecretion (Podszywalow-Bartnicka et al., 2010). To determine the inhibitory effect of AnxA6 on exocytosis of dopamine, we were looking for molecular partners of AnxA6 in PC12 cells. We hypothesized that AnxA6 interacts with phospholipase D1 (PLD1), an enzyme involved in the fusion step. By using confocal microscopy and total internal reflection fluorescence microscopy, we found that isoform 1 of AnxA6 and Phospholipase D1 are both recruited on the surface of vesicles upon stimulation of PC12 cells. AnxA6 inhibited phospholipase D activity as revealed by our enzymatic assay based on infrared spectroscopy. To conclude, we propose that AnxA6 is not only implicated in membrane organization by its capacity to bind to negative charged phospholipids and to cholesterol, but AnxA6 is also affecting PLD1 activity, changing membrane lipids composition

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Crépeau, Joël. "Development of a single-mode interstitial rotary probe for In Vivo deep brain fluorescence imaging." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29428/29428.pdf.

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Ce mémoire rend compte de l’expertise développée par l’auteur au Centre de recherchede l’Institut universitaire en santé mentale de Québec (CRIUSMQ) en endoscopie fibrée. Il décrit la construction d’un nouveau type de microscope optique, le MicroscopeInterstitiel Panoramique (PIM). Par la juxtaposition d’un court morceau de fibre à gradientd’indice et d’un prisme à l’extrémité d’une fibre monomode, la lumière laser estfocalisée sur le côté de la sonde. Pour former une image, cette dernière est rapidementtournée autour de son axe pendant qu’elle est tirée verticalement par un actuateurpiézo-électrique. Ce design de système rotatif d’imagerie interstitielle peu invasif est uneffort pour limiter les dégâts causés par la sonde tout en imageant la plus grande régionpossible en imagerie optique cérébrale profonde.
This thesis documents the expertise developed by the author at the Centre de recherchede l’Institut universitaire en santé mentale de Québec (CRIUSMQ) in fibered endoscopy,particularly the design and construction of a new kind of optical microscope: ThePanoramic Interstitial Microscope (PIM). Through the juxtaposition of a short piece ofGraded-Index fibre and a prism at the end of a single-mode fibre, laser light is focussedon the side of the probe. To form an image, the latter is quickly spun around its axiswhile it is being pulled vertically by a piezoelectric actuator. This minimally invasivefluorescence rotary interstitial imaging system is an endeavor to limit the damage causedby the probe while imaging enough tissue to provide good context to the user in deep brain optical imaging.

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Biasiori-Poulanges, Luc. "Fragmentation aérodynamique d’une goutte liquide induite par une onde de choc plane High-magnification shadowgraphy for the study of dropbreakup in a high-speed gas flow On the formation and recurrent shedding of ligaments in droplet aerobreakup Data on eosin y solutions for laser-induced fluorescence in water flows Multimodal imaging for intra-droplet gas-cavity observation during droplet fragmentation." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0002.

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Ce travail de thèse propose une description originale de la fragmentation aérodynamique d’une goutte d’eau, induite par une onde de choc plane, pour des régimes à la frontière entre les modes gouvernés par l’instabilité de Rayleigh-Taylor et ceux dominés par l’instabilité de Kelvin-Helmholtz. Un banc expérimental composé d’un tube à choc couplé à des diagnostics d’imagerie rapide est exploité pour caractériser les processus de fragmentation. Les résultats expérimentaux sont complétés par des simulations numériques réalisées à partir du code multiphasique compressible open-source ECOGEN. L’effet de l’onde de choc sur la goutte est évalué grâce à une modélisation théorique basée sur l’acoustique géométrique permettant de décrire la dynamique spatio-temporelle des réflexions d’onde à l’intérieur de la goutte et de prédire le lieu des points de plus haute densité d’énergie. Le champ de pression est résolu à partir de simulations numériques qui indiquent que la tension de rupture de l’eau est atteinte pour une onde de choc évoluant à un nombre de Mach de 1.7. Dès lors, un processus de cavitation dont les conséquences sur la dynamique de la fragmentation pourraient être significatives, est possible. Concernant la dynamique interfaciale, les expériences comme les simulations révèlent le développement d’une perturbation azimutale transverse à l’origine d’une structure ligamentaire périodique. Une analyse de Fourier des résultats numériques 3-D suggère que l’initiation de cette déstabilisation est indépendante des effets capillaires, à l’inverse de sa croissance. La dynamique ligamentaire apparaît être un processus cyclique dont la fréquence est celle du lâché de vortex dans le sillage del a goutte. Ce schéma récurrent cesse après quatre cycles. Il s’en suit alors la perte de l’intégrité structurelle du corps résiduel de la goutte des suites du développement d’une cavité gazeuse, dans le liquide, qui agit comme une région de fragilité et donc, facilite la fragmentation
This thesis proposed a groundbreaking description of the shock-induced aerodynamic fragmentation of a water droplet at the transition of the Rayleigh-Taylor Piercing and the Shear-Induced Entrainment regimes. An experimental facility consisting of a shock tube and high-speed imaging diagnostics is used to investigate the fragmentation processes. Experimental results are supported with numerical simulations performed with the open-source code ECOGEN dedicated to multiphase compressible flows. The shock wave effect on the droplet is assessed by a theoretical modelling based on geometrical acoustics which allows for the description of the wave spatio-temporal dynamics and enables to predict the time-dependent location of the highest energy density. Pressure fields are determined using numerical simulations. It appears that the water tensile rupture is reached for a shock wave Mach number of 1.7 from which bubble cloud cavitation may occur by causing signification changes in the fragmentation dynamics. As regards to the interfacial dynamics, both experiments and numerical simulations show the development of a transverse azimutal modulation resulting in the periodic ligament structure at the droplet surface. Contrary to the modulation growth, its initiation seems to be independent of the capillary effects as revealed by a Fourier analysis of the 3-D numerical results. The ligament dynamics is a cyclic process driven by the vortex shedding process in the wake of the droplet. Four cycles have been observed before the residual droplet core breaks up owing to the growth of an air cavity inside the droplet that acts as weak spot, and thus facilitating the droplet split-off

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Banerjee, Amartya. "Beta-Peptide Helices As Transmembrane Domains: Aggregation, Recognition and Lipid-Peptide Interaction." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E56E-5.

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প্লাজমা ঝিল্লি একটি প্রাথমিক কার্যকরী ইউনিট হিসাবে একটি কোষ দক্ষ কার্যকরী জন্য অপরিহার্য হিসাবে গণ্য করা হয়। এই ঝিল্লিগুলি বহিরাগত কোষের কোষের ভিতরের অংশটিকে পৃথক করে এবং পাশাপাশি এটি জুড়ে চলমান নিয়ন্ত্রনের বাধা হিসাবে কাজ করে। প্লাজমা ঝিল্লিগুলি বিভিন্ন বিভিন্ন উপাদানের সাথে গঠিত, তবে সবার মধ্যে, ঝিল্লি প্রোটিনগুলিকে বৈজ্ঞানিক সম্প্রদায়ের দ্বারা প্লাজমা ঝিল্লির প্রধান কাঠামোগত এবং কার্যকরী স্তম্ভগুলির মধ্যে সর্বসম্মতিক্রমে গ্রহণ করা হয়। বৈজ্ঞানিক গবেষণায়, ঝিল্লী প্রোটিনগুলির কার্যকারিতা গুরুতর রোগের জন্য দায়ী বলে মনে করা হয়েছে। সুতরাং, এটি কৃত্রিম ট্রান্সমেম্রেন প্রোটিন ডোমেনগুলি ডিজাইন এবং বিকাশের জন্য একটি দুর্দান্ত বৈজ্ঞানিক আগ্রহ রয়েছে যা স্বাভাবিকের ত্রুটিগুলির সমাধান করতে সক্ষম। এই প্রোটিন ডোমেনগুলির ভাঁজ গঠন এবং ট্রান্সমেমব্রেন গতিবিদ্যা পিছনে আণবিক শক্তি এবং অন্যান্য পদার্থ-রাসায়নিক প্রক্রিয়াগুলি বোঝা হালনাগাদকৃত কৃত্রিম ট্রান্সমিম্ব্রেন প্রোটিন ডোমেনগুলি বিকাশের প্রক্রিয়ার অবিচ্ছেদ্য অংশ। গত দুই দশক ধরে, বিটা-পেপটাইডগুলি আরও প্রতিশ্রুতিশীল পেপটিডোমিম্যাটিক মোটিফগুলির মধ্যে একটি হিসাবে বিবর্তন হয়েছে। প্রোটিলাইটিক হ্রাসের বিরুদ্ধে অসাধারণ স্থিতিশীলতা এবং স্থিতিশীল হেলিকাল সেকেন্ডারি স্ট্রাকচার যেমন 14 -12- এবং বিকল্প 10 / 1২-হেলিসেসগুলি 4-6 এমিনো এসিডগুলি তৈরি করার ক্ষমতা, এর পিছনে দুটি প্রধান কারণ peptidomimetics মধ্যে β-peptides এর বিমোচন এন্ট্রি। অন্যান্য গুরুত্বপূর্ণ প্যারামিটারগুলির পাশাপাশি পেপটাইডের হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তটি ট্রান্সমেম্রেন সন্নিবেশ এবং বিস্তারের ক্ষেত্রে গুরুত্বপূর্ণ ভূমিকা বলে মনে করা হয়। পেপটাইডগুলির হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের সরাসরি পরীক্ষামূলক সিদ্ধান্ত অত্যন্ত চ্যালেঞ্জিং হচ্ছে, হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের সম্ভাব্য প্রভাবগুলি কেবলমাত্র তাত্ত্বিকভাবে প্রস্তাবিত। অতএব, এই থিসিসের প্রধান উদ্দেশ্যগুলি ট্রান্সমেম্রেন সন্নিবেশ এবং বিস্তারের পাশাপাশি পরোক্ষ পরীক্ষার মাধ্যমে সেলুলার উপসর্গের মধ্যে হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের সম্ভাব্য ভূমিকা পালন করা। সাধারণভাবে, β-peptides নির্দিষ্ট হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্ত থাকে তবে প্রাকৃতিকভাবে ঘটমান α-peptide analogues এর তুলনায় বিপরীত দিকে থাকে। ধারণাটি হল বিটা-পেপটাইডের একটি ধরণের সনাক্তকরণ এবং সংশ্লেষ করা যার প্রায় মোট কোনও হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্ত নেই এবং β-peptides সহ এবং হেলিক্যাল ম্যাক্রো-ডিপোল ছাড়া ট্রান্সমেমব্রেন সন্নিবেশ স্টাডিজগুলি অন্যান্য সমস্ত পরামিতিগুলিকে ধ্রুবক রাখে। ক্ষেত্রে, তারা ঝিল্লি সন্নিবেশের জন্য কোন ডিফারেনশিয়াল ক্ষমতা প্রদর্শন করে, এটি পরীক্ষামূলকভাবে নিজ নিজ পদার্থ-রাসায়নিক ঘটনায় হেলিক্যাল ম্যাক্রো-ডিপোলের ভূমিকা নির্দেশ করবে। ব্যাপক গবেষণার পরে, বিকল্প β3 / β2-amino অ্যাসিডের সংযোজিত বিকল্প 10/12-হেলিকাল β-peptides তাদের অনন্য রূপান্তরিত অভিযোজন কারণে সামগ্রিক অলঙ্কৃত হেলিক্যাল ম্যাক্রো-ডিপোল পাওয়া যায় নি। অতএব, বিভিন্ন ধরণের β-peptides সহ 14-, 12- এবং বিকল্প 10/12-হেলিক্যাল পেপটাইড তুলনীয় ট্রান্সমেম্রেন দৈর্ঘ্য এবং ক্রম সহ বিভিন্ন সিন্থেটিক কৌশল মিশ্রিত করে সংশ্লেষিত করার পরিকল্পনা করা হয়েছে, যেমন মাইক্রোওয়েভ সহায়তায় ম্যানুয়াল SPPS, অ- মাইক্রোওয়েভ সহায়তায় ম্যানুয়াল SPPS, এবং ফ্লুরোস-ট্যাগ সংযুক্ত তরল ফেজ পেপটাইড সংশ্লেষণ। পরের ধাপে, পেপাইডাইডগুলির ট্রান্সমেমব্রেন সন্নিবেশ হাইড্রোফোবিক মাইক্রো-এনভায়রনমেন্ট সংবেদনশীল ট্রপ-ফ্লোরেসেন্স স্পেকট্রোস্কপি দ্বারা পরীক্ষা করা হবে। তিনটি ভিন্ন লিপিড, ডিএলপিসি / ডিএমপিসি / পিওপিসি এর একই গোষ্ঠীটি বিভিন্ন 14-, 12-এবং বিকল্প 10/12-হেলিক্যাল পেপাইডাইডের জন্য তুলনামূলক দৈর্ঘ্যের সাথে এইভাবে নির্বাচিত হয় যে নেতিবাচক হাইড্রোফোবিক মেলেম্যাচ ধীরে ধীরে একটি প্রায় পুরোপুরি hydrophobic ম্যাচিং পরিস্থিতি। এটি ভালভাবে জানা গেছে যে নেতিবাচক হাইড্রোফোবিক মেলেম্যাচের থ্রেশহোল্ড মানের উপরে ট্রান্সমেমব্রেন সন্নিবেশ সম্ভব নয়। অন্য দিকে, ইথানল মত শর্ট চেইন অ্যালকোহল, অ্যাসিড চেইন interdigitating দ্বারা লিপিড ঝিল্লি বেধ কমানোর একটি উচ্চারণ প্রভাব ভোগ করতে পরিচিত। অতএব, ETOH এর ক্রমবর্ধমান বৃদ্ধি ঘনত্বটি বিভিন্ন পেপটাইডের জন্য ব্যবহার করা হবে এবং একই লিপিডের জন্য একই পেপাইডাইডগুলির জন্য প্রতিটি পেপাইডাইডের জন্য প্রয়োজনীয় ন্যূনতম থ্রেশহোল্ড ঘনত্বের অনুরূপ নেতিবাচক হাইড্রোফোবিক মেলেম্যাচটি সাবধানে ন্যূনতম ক্ষতিপূরণ নেতিবাচক ক্ষতিপূরণ হিসাবে পর্যবেক্ষণ করা হবে। Trp-fluorescence বর্ণালী ক্রিয়ার সাহায্যে সফল ট্রান্সমেমব্রেন সন্নিবেশের জন্য অপরিসীম প্রয়োজন। এই পরীক্ষামূলক ফলাফল থেকে, এই সিদ্ধান্তে পৌঁছানো সম্ভব হবে যে পেপাইডাইডটি ETOH- এর আরো কম ঘনত্বের প্রয়োজন, যা নেতিবাচক মেলামেশের উচ্চতর ক্ষতিপূরণ, লিপিড ঝিল্লিতে পুনর্গঠন করতে সফলভাবে, ট্রান্সমেম্রেন সন্নিবেশ এবং বিস্তারের দিকে কম প্রবণ। ক্ষেত্রে, হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের সাথে এবং পেপাইডাইডগুলি এই আচরণের প্রতি কোনও ডিফারেনশিয়াল প্রবণতা প্রদর্শন করে, এটি পরোক্ষভাবে নির্দেশ করে এবং পরীক্ষামূলকভাবে ট্রান্সমেম্রেন সন্নিবেশ এবং স্প্যানিংয়ের মধ্যে হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের উল্লেখযোগ্য ভূমিকা যাচাই করবে (যেহেতু পেপাইডাইডগুলির মধ্যে প্রধান পার্থক্য হল হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের উপস্থিতি এবং অনুপস্থিতি)। তাছাড়া, লিপিড পরিবেশের অভ্যন্তরে যখন চারিত্রিক হেলিক্যাল প্যাটার্নটি রক্ষণাবেক্ষণ করা হয় কিনা তা ব্যাখ্যা করার জন্য, বিভিন্ন পেপাইডাইডগুলির দ্বিতীয় হেলিক্যাল কাঠামো সমাধান এবং পাশাপাশি অভ্যন্তরীণ লিপিড ভিসিক্যালগুলিতে নির্ধারণ করা হবে। তাপমাত্রা নির্ভর সিডি-স্পেকট্রসকপি দ্বারা সমাধান হিসাবে তুলনায় লিপিড vesicles ভিতরে যখন 14- এবং 10/12-হেলিক্যাল পেপটাইড স্থিতিশীলতা পরিবর্তন করা হয় কিনা তা পরীক্ষা করা হবে। হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তটি সমাধান বা অভ্যন্তরীণ লিপিড vesicles মধ্যে সেকেন্ডারি হেলিকাল কাঠামো স্থিতিশীল করতে কোনো প্রভাব আছে কিনা তাও ইঙ্গিত করে। অবশেষে, 6-অ্যামিনো অ্যাসিড দীর্ঘ শৃঙ্খল চেইন 14-হেলিকাল এবং 10 / 1২-হেলিকাল 5 (6) -ফ্যাম সংযুক্ত পেপটাইডগুলি মানব ব্রোঞ্চিয়াল এডেনোকার্কিনোমা সেল লাইন A549 ব্যবহার করে সেলুলার আপটেক স্টাডিজের জন্য সংশ্লেষিত হয়। প্রথমটি ক্লোজোজেনিক অ্যাস এবং এমটিটি-অ্যাস দ্বারা একই কোষ লাইনে সাইটোটক্সিসটিটি পরীক্ষা করা হয়। যদি 1 μM ঘনত্ব না হওয়া পর্যন্ত অ-সাইটোটক্সিক পাওয়া যায়, তাহলে ফ্লোরোসেন্স অ্যাক্টিভেটেড সেল সোর্সিং (FACS) দ্বারা পরিমাণগত সেলুলার উত্তোলনের দক্ষতার দিকে আরও গবেষণা 14- এবং বিকল্প 10/12-হেলিক্যাল পেপাইডাইডগুলি হয়। একটি সুপরিচিত কোষ তীক্ষ্ণ পেপটাইড, এইচআইভি -1 ট্যাট, একটি রেফারেন্স মান হিসাবে ব্যবহৃত হয়। দুটি লক্ষ্য পেপটাইডগুলির মধ্যে সেলুলার আপটেক কার্যকারিতাগুলির মধ্যে কোন পার্থক্য পরীক্ষামূলকভাবে নির্দেশ করবে যে হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তটি ট্রান্সমেমব্রেন সন্নিবেশ এবং বিস্তারকে প্রভাবিত করে না তবে সেলুলার অ্যাকটেককেও নিয়ন্ত্রণ করে। FACS ফলাফলগুলি নিশ্চিত এবং সমর্থন করার জন্য, পেপাইডাইডগুলি কন confocal লেজার স্ক্যানিং ফ্লুরোসেন্স মাইক্রোস্কপি অধীনে দৃশ্যমান হবে। মাইক্রোস্কোপি ইমেজিং প্রদর্শন করবে যে টার্গেট পেপাইডগুলি প্রকৃতপক্ষে সেল অনুপ্রবেশের মাধ্যমে অভ্যন্তরীণ হয় কিনা বা শুধুমাত্র ঝিল্লিতে আটকা পড়ে। উপরন্তু, যদি কোন লক্ষ্য β-peptides উল্লেখযোগ্য কোষ অনুপ্রবেশ ক্ষমতা পাওয়া যায়, এটি নতুনত্ব, হাইড্রোফোবিক, uncharged সেল ভেতরে পেপটাইড (সিপিপি) প্রার্থী যারা proteases উপস্থিতি স্থিতিশীল স্থিতিশীল দিকে একটি নতুন বর্ণমালা খুলতে হবে। অবশেষে, এই সমস্ত গবেষণাগুলি পরীক্ষামূলকভাবে ট্রান্সমেম্রেন সন্নিবেশ, বিস্তার এবং সেলুলার উপসাগরীয় অঞ্চলে ঝিল্লি প্রোটিন ডোমেনের হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের নিয়ন্ত্রক প্রভাবের উপর আলোকপাত করবে। এই তথ্যটি এই গুরুত্বপূর্ণ পদার্থ-রাসায়নিক ঘটনাগুলিতে পেপটাইড হেলিক্যাল ম্যাক্রো-ডিপোল মুহূর্তের প্রভাবকে মোকাবেলা করবে এবং β-পেপটাইড ভিত্তিক মডেল ট্রান্সমেম্রেন ডোমেন সিস্টেমগুলি পাশাপাশি β-পেপটাইড-ভিত্তিক নতুন প্রজন্মের কোষ তীব্র পেপটাইডগুলি ডিজাইনে সহায়তা করবে।

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40

Septiadi, Dedy. "Optical imaging and drug delivery using soft- and hard- nanomaterials." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAF036/document.

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Le travail décrit dans cette thèse se concentre sur le développement de matériaux « durs et mous » ainsi que leur interaction avec les cellules biologiques pour une application finale dans le domaine de la théranostique couvrant l'imagerie, la détection, la thérapie génique et la thérapie du cancer. Dans ce contexte, nous avons tout d'abord étudié l'utilisation de complexes (II) de platine phosphorescents auto-assemblés comme sonde cellulaire. Nous avons étendu l'idée de bio-imagerie en introduisant un concept d’imagerie basée sur l’émission stimulée où nous étions en mesure de générer un laser provenant d'une cellule biologique unique sans utiliser de cavité optique conventionnelle. En outre, des nano-transporteurs multifonctionnels à base de matières poreuses dures à savoir des zéolithes L et des nanoparticules de silice mésoporeuse pour de la « drug delivery » (relargage de médicaments et d’oligonucléotides) in vitro ide ont été développés avec succès et testés pour le traitement du glioblastome. Un autre nano-vecteur, qui est construit à partir de silice biodégradable, a également été synthétisé et sa capacité d'encapsuler des protéines et de les libérer dans les cellules vivantes lors de la dégradation de la structure dans un environnement réducteur a été démontrée. Enfin, l'utilisation de nouveaux matériaux plasmonique sur la base de nanoparticules d'argent enrobées de silice cassable pour la détection d'agents réducteurs a été mise en valeur
The work described in this thesis focuses on the development of soft- and hard-materials as well as their interaction with biological cells for applications in the field of theranostics covering imaging, sensing, and gene, and cancer therapy. In this context, we first investigated the use of phosphorescent self-assembled platinum(II) complexes as cellular probes. We extended the concept stimulated emission-based bioimaging by generating a laser-like emission coming from a single biological cell without using any conventional optical cavity. In addition, we successfully developed multifunctional nanocarriers based on porous hard materials, namely zeolites-L and mesoporous silica nanoparticles for drug and oligonucleotide delivery in vitro and they were tested to treat glioblastoma. Another nanovector, which is constructed from biodegradable silica, was also synthesized and its ability to encapsulate proteins and release them in living cells upon degradation of the structure in reductive environment was demonstrated. Finally, the use of novel plasmonic structures based on breakable silica-coated silver nanoparticles for detection of reducing agents was successfully investigated

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41

Moreau, David. "Infrared stimulation of neurons." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0050/document.

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L’exposition aux radiations laser infrarouge peut être utilisée afin de dépolariser des neurones et stimuler l’activité neuronale. Le mécanisme sous-jacent d’une telle stimulation est supposé résulter d’une interaction photothermique. En effet, l’absorption de la radiation infrarouge par le tissu biologique cible, et l’eau qu’il contient, induit une augmentation de température de manière localisée, qui soit influencerait directement les propriétés membranaires de la cellule soit agirait par le biais de l’activation de canaux ioniques thermo-sensibles. Dans la plupart des cas, l’activité électrique des neurones est mesurée électriquement à l’aide de microélectrodes, mais elle peut également être sondée par le biais de la microscopie de fluorescence faisant intervenir des indicateurs calciques. Dans ce travail, l’impact de l’exposition à la radiation infrarouge sur les signaux calciques de neurones a été étudié dans le but d’éclaircir et de préciser le mécanisme résultant de l’interaction photothermique. Des neurones HT22, issus d’hippocampe de souris, et des cellules U87, issues d’un glioblastome humain, ont été utilisés en tant qu’exemples de cellules électriquement excitables et non excitables respectivement. Afin de mesurer la température et les signaux calciques au niveau cellulaire, les fluorophores Rhodamine B et Fluo-4 ont été employés. Le montage, par conséquent tout optique, pour étudier l’influence de l’exposition infrarouge sur l’activité neurale est donc présenté, ainsi que la démarche scientifique menant à l’identification de l’implication de l’activité de la phospholipase C dans le mécanisme étudié. La possibilité de stimuler l’activité neurale in vivo, dans le cerveau d’une souris, avec une mesure simultanée des signaux calciques, est également démontrée à l’aide de souris transgéniques exprimant le GCaMP6S
Infrared laser light radiation may be used to depolarize neurons and to stimulate neural activity. The underlying mechanism of such stimulation is believed to happen due to a photothermal interaction. The absorption of the infrared radiation by the targeted biological tissue inducing a local temperature increase which either directly influence membrane properties or act via temperature sensitive ion channels. Action potentials are typically measured electrically in neurons with microelectrodes, but they can also be observed using fluorescence microscopy techniques that use synthetic or genetically encoded calcium indicators. In this work, we studied the impact of infrared laser light on neuronal calcium signals to address the mechanism of these thermal effects. HT22 mouse hippocampal neurons and U87 human glioblastoma cells were used loaded with the fluorescent calcium dye Fluo-4 and with the temperature sensitive fluorophore Rhodamine B to measure calcium signals and temperature changes at the cellular level. Here we present our all-optical strategy for studying the influence of infrared laser light on neural activity, and the scientific approach leading to conclusion of the involvement of Phospholipase C activity during infrared neural stimulation. The ability of infrared exposure to trigger neural activity in mice brain in vivo is also investigated with the use of GCaMP6s transgenic mice

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42

Palma, Philip Charles. "Laser-induced fluorescence imaging in free-piston shock tunnels." Phd thesis, 1999. http://hdl.handle.net/1885/144483.

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43

Capewell, Dale L. "Planar Laser Induced Fluorescence Imaging and Monte Carlo Simulations of Pulsed Laser Ablation." Thesis, 1997. https://thesis.library.caltech.edu/111/3/Capewell_dl_1997.pdf.

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The first reported planar laser-induced fluorescence (PLIF) images depicting the relative ground-state, neutral density of Si within a pulsed laser ablation (PLA) plume as it expands into vacuum and 10 mTorr Ar are presented. Because of the high flow speeds in PLA plumes and the narrow bandwidth of typical lasers, several images acquired with the laser detuned incrementally must be superimposed to produce images which compensate for Doppler shifts. Density profiles of Si along the axis of symmetry as a plume expands into Ar at pressures of 0-150 mTorr demonstrate the influence of a background gas and substrate on the expanding plume in the interval 0 < t < 5μs. In-flight production of SiO along the contact as an Si plume expands into 1.0 Torr air is demonstrated in the first reported images of a reactive intermediate species produced during PLA.

The expansion of Si into both 10 mTorr and 100 mTorr Ar is investigated using the technique of Direct Simulation Monte Carlo (DSMC), with a simple ablation model used to generate the Si plume. As a consequence of the rapid displacement of background gas, i.e. the snowplow effect, the plume divides into two components, one which travels nearly collisionlessly toward the substrate and one which interacts more strongly with the gas. At 10 mTorr, collisions between fast component Si atoms and Ar atoms during the period t < 250 ns are responsible for most of the energy transfer from Si to Ar. This results in the creation of a fast (15 eV), collisionless Ar component which impacts the substrate shortly after the fast Si component arrives, but does not result in thermal heating. At 100 mTorr, the energy transfer from the plume to the Ar gas occurs on a μs time scale and is attributed primarily to thermal heating. The energy of the fast Ar component decreases to about 5 eV.

Finally, the DSMC technique is employed to study the expansion of Si into both 10 mTorr and 100 mTorr O₂. The chemical reaction Si + O₂ → SiO + O is investigated, including rotational and vibrational excitation the diatomic molecules O₂ and SiO. At both pressures, SiO first appears along the sides of the expanding plume and, at 100 mTorr, appears only along the contact front between the Si and O₂. This result compares well will PLIF data. An examination of the O₂ rotational temperature indicates that the background gas is heated along a conical surface whose tip is located at the ablation spot as the plume expands.

Collectively, these simulations demonstrate the potential of the DSMC method to provide quantitative information about the reactive expansion of a wide variety of PLA plumes into rarified background gas mixtures, and study the particle flux onto a substrate when parameters such as background gas pressure and composition are varied.

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44

Burns, Ross Andrew. "Development of scalar and velocity imaging diagnostics for supersonic hypermixing strut injector flowfields." Thesis, 2014. http://hdl.handle.net/2152/28316.

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A new diagnostic technique for studying the turbulent mixing characteristics of supersonic mixing flowfields is developed and implemented in two Mach 3 mixing flowfields. The diagnostic utilizes simultaneous particle image velocimetry and quantitative planar laser-induced fluorescence of krypton gas to study the interaction between turbulent scalar and velocity fields. The fluorescence properties of krypton gas are determined; measurements of the pressure and temperature dependence of the collisional quenching rates and cross-sections are made for various mixtures with krypton. The gases tested in this fashion include helium, nitrogen, air, oxygen, and ethylene. Additional measurements are performed to measure the relative two-photon absorption cross-section for krypton gas. The non-dimensional quenching rates are found to follow a power-law dependence for temperature, while the pressure dependence of the total quenching rate is found to be linear. Two injection flowfields are studied for their general topology and kinematic characteristcs. The first injector model is a basic injector meant to serve as a baseline case; there are no hypermixing elements present in this model. The second model is an asymmetric, unswept hypermixing injector featuring 15 degree expansive ramps flanking a central block. These studies utilize particle image velocimetry in planar and stereoscopic configurations in various planes. Results for the mean flowfield show distinct differences between the two flowfields; the planar injector flowfield is shown to be highly two-dimensional and exhibits minimal coherent unsteady behavior. The hypermixing injector flowfield exhibits a highly three-dimensional wake, with a pair of stream-wise vortices driving both mean deviations in the flowfield and considerable vortical coupling in the span-wise direction. Simultaneous krypton PLIF and PIV are employed in the two mixing flowfields. An assay of the dependence of the krypton mole fraction calculations on the fluorescence signal is performed. The overall sensitivity and the resulting dynamic range of the calibration is dictated largely by the reference mole fraction. Additionally, several different theoretical models of the temperature dependence of the fluorescence signal are studied to assess their validity and influence over the PLIF calibration procedure. Finally, the technique is employed in the two mixing flowfields, and a brief analysis of the mean and unsteady behavior of the two is conducted.
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Lochman, Bryan John. "Technique for imaging ablation-products transported in high-speed boundary layers by using naphthalene planar laser-induced fluorescence." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-08-1922.

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A new technique is developed that uses planar laser-induced fluorescence (PLIF) imaging of sublimated naphthalene to image the transport of ablation products in a hypersonic boundary layer. The primary motivation for this work is to understand scalar transport in hypersonic boundary layers and to develop a database for validation of computational models. The naphthalene is molded into a rectangular insert that is mounted flush with the floor of a Mach 5 wind tunnel. The distribution of naphthalene in the boundary layer is imaged by using PLIF, where the laser excitation is at 266 nm and the fluorescence is collected in the range of 320 to 380 nm. To investigate the use of naphthalene PLIF as a quantitative diagnostic technique, a series of experiments is conducted to determine the linearity of the fluorescence signal with laser fluence, as well as the temperature and pressure dependencies of the signal. The naphthalene fluorescence at 297 K is determined to be linear for laser fluence that is less than about 200 J/m². The temperature dependence of the naphthalene fluorescence signal is found at atmospheric pressure over the temperature range of 297K to 525K. A monotonic increase in the fluorescence is observed with increasing temperature. Naphthalene fluorescence lifetime measurements were also made in pure-air and nitrogen environments at 300 K over the range 1 kPa to 40 kPa. The results in air show the expected Stern-Volmer behavior with decreasing lifetimes at increasing pressure, whereas nitrogen exhibits the opposite trend. Preliminary PLIF images of the sublimated naphthalene are acquired in a Mach 5 turbulent boundary layer. Relatively low signal-to-noise-ratio images were obtained at a stagnation temperature of 345 K, but much higher quality images were obtained at a stagnation temperature of 380 K. The initial results indicate that PLIF of sublimating naphthalene may be an effective tool for studying scalar transport in hypersonic flows.
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Düwel, Isabell [Verfasser]. "Spray combustion diagnostics with tracer based laser induced fluorescence imaging / vorgelegt von Isabell Düwel." 2007. http://d-nb.info/984134751/34.

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Shian, Miin-liang, and 蕭敏良. "Measurement of velocity distributionof seeded jet beams by laser-induced fluorescence and imaging techniques." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/55381760113190122072.

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Fox, Jodie Simone. "Visualisation and instantaneous planar laser-induced fluorescence imaging techniques developed and applied to turbulent flows." Phd thesis, 2003. http://hdl.handle.net/1885/150353.

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"Visualization of Brain Tumors with Intraoperative Confocal Laser Endomicroscopy." Doctoral diss., 2020. http://hdl.handle.net/2286/R.I.57300.

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abstract: Intraoperative diagnosis in neurosurgery has traditionally relied on frozen and formalin-fixed, paraffin-embedded section analysis of biopsied tissue samples. Although this technique is considered to be the “gold standard” for establishing a histopathologic diagnosis, it entails a number of significant limitations such as invasiveness and the time required for processing and interpreting the tissue. Rapid intraoperative diagnosis has become possible with a handheld confocal laser endomicroscopy (CLE) system. Combined with appropriate fluorescent stains or labels, CLE provides an imaging technique for real-time intraoperative visualization of histopathologic features of the suspected tumor and healthy tissues. This thesis scrutinizes CLE technology for its ability to provide real-time intraoperative in vivo and ex vivo visualization of histopathological features of the normal and tumor brain tissues. First, the optimal settings for CLE imaging are studied in an animal model along with a generational comparison of CLE performance. Second, the ability of CLE to discriminate uninjured normal brain, injured normal brain and tumor tissues is demonstrated. Third, CLE was used to investigate cerebral microvasculature and blood flow in normal and pathological conditions. Fourth, the feasibility of CLE for providing optical biopsies of brain tumors was established during the fluorescence-guided neurosurgical procedures. This study established the optimal workflow and confirmed the high specificity of the CLE optical biopsies. Fifth, the feasibility of CLE was established for endoscopic endonasal approaches and interrogation of pituitary tumor tissue. Finally, improved and prolonged near wide-field fluorescent visualization of brain tumor margins was demonstrated with a scanning fiber endoscopy and 5-aminolevulinic acid. These studies suggested a novel paradigm for neurosurgery-pathology workflow when the noninvasive intraoperative optical biopsies are used to interrogate the tissue and augment intraoperative decision making. Such optical biopsies could shorten the time for obtaining preliminary information on the histological composition of the tissue of interest and may lead to improved diagnostics and tumor resection. This work establishes a basis for future in vivo optical biopsy use in neurosurgery and planning of patient-related outcome studies. Future studies would lead to refinement and development of new confocal scanning technologies making noninvasive optical biopsy faster, convenient and more accurate.
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Doctoral Dissertation Neuroscience 2020

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Gouda, Prachi Pragyan. "Refractive-Index-Matched Fluorescent Particle Image Velocimetry for Investigation of Flow in Immersed Granular Materials." Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5820.

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Refractive-Index-Matched Fluorescent Particle Image Velocimetry for Investigation of Flow in Immersed Granular Materials The ubiquity of granular materials and their importance in everyday life, industry, and nature make their study imperative for proper manipulation of the flow. As granular materials are opaque, optical imaging experiments are limited to studies at the free surface or transparent boundaries of the flow. Though techniques like magnetic resonance imaging and X-ray tomography have been used to obtain information from the interior of the flow system, these studies are limited to a small class of granular materials. Therefore, a modified yet simple optical imaging technique that can access the bulk of the flow is desirable. Our study employs refractive-index-matched fluorescent particle image velocimetry (RIM FPIV) to obtain information about the bulk of the flow. In RIM FPIV, the system of dry granular materials is made transparent by adding a suitable liquid whose refractive index is close to that of the particles (glass beads). The addition of liquid results in immersed granular materials, in which the particles are completely submerged in the liquid. Reported literature indicates that immersed granular materials exhibit shear banding and rate-independent rheology at slow shear rates, just like dry granular materials. A recent study using discrete element method (DEM) simulations and experiments reports a dilation-driven vortex in dry granular materials in the slow flow regime. However, the opacity of the granular materials restricted the experimental studies to visualizing only the free surface of the flow. By utilizing the similarities between the two media, our study on an immersed granular medium could give us insight into the flow behaviour in the bulk of dry granular systems. In this thesis, we experimentally study the flow of immersed granular materials and compare our observations with that of dry granular media. We perform experiments on slowly sheared immersed granular materials in a cylindrical Couette and present velocity profiles for the free surface using conventional PIV and the bulk of the flow using RIM FPIV. We observe broadening of the shear band in immersed granular materials and explain how the presence of fluid in interstitial spaces is responsible for such behaviour. We also report increased radial flow in the free surface of immersed granular materials due to enhancement of dilation by the fluid. In our RIM FPIV experiments, the velocity profiles in the bulk of the flow show radially inward flow close to the free surface and radially outward flow close to the bottom of the Couette cell. This observation is consistent with the simulations previously performed on a system of dry granular materials, indicating a circulating axial flow. Therefore, this study is a good starting point for experimentally validating the secondary axial flow in the bulk of both immersed and dry granular materials.

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Dissertations / Theses on the topic 'Laser Fluorescence Imaging'

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