Dissertations / Theses on the topic 'Fluorescence sensing'
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Hussain, Faeiza. "Fluorescence-based glucose sensing." Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417288.
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Dandin, Marc Péralte. "Towards integrated fluorescence sensing." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7811.
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Thesis (M.S.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Nagl, Stefan. "Fluorescent multiple chemical sensing using time-domain fluorescence lifetime imaging." kostenfrei, 2008. http://www.opus-bayern.de/uni-regensburg/volltexte/2008/996/.
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Zhou, Xiaobo. "Design, synthesis and sensing properties of chiral amine-based fluorescent probes." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1442.
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dos, Santos Almeida Carina Marisa. "Nanomaterials for intracellular fluorescence imaging and sensing." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45498.
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This thesis explores the use of nanomaterials for bioimaging using conjugated polymer nanoparticles (CPNs) and porous silicon nanoneedles (PSNs) for intracellular biosensing. CPNs have recently started being used in biomedical research due to their outstanding optical properties, such as large extinction coefficients and high fluorescence brightness. Several strategies have been developed to stabilise their surface and provide functional groups for subsequent biomolecule conjugation. Peptides are highly customisable molecules and possess several advantages when compared to other capping ligands. A one-pot synthesis and peptide functionalisation method for CPNs using peptide amphiphiles was developed and it was shown that the presence of the peptide amphiphile did not affect the advantageous optical properties of CPNs. By using peptide amphiphiles with different characteristics, it was possible to tailor the cellular uptake of peptide-CPNs, proving the bioactivity of these nanoparticles. Importantly, none of the used peptide-CPNs demonstrated cell cytotoxicity. Other conjugated polymer (CPs) were used to synthesise peptide-CPNs of different colours, demonstrating the versatility of this method. PSNs have been developed for probing the intracellular environment for delivery or sensing. Access to the cytoplasm of cells is difficult using other methods and therefore PSNs are a suitable candidate for a biocompatible and minimally invasive approach. PSNs were functionalised to a cathepsin B (CTSB) protease cleavable peptide with an imaging moiety that would be released upon CTSB sensing. Optimal conditions for the biosensor assembly were determined in silicon chips. Moreover, two oesophageal cell lines were chosen for in vitro studies and their CTSB expression studied. Incubation of PSNs with cells showed tight interfacing without harming to cells. Finally, an intracellular pH sensor using PSNs was developed and it showed linear response in a biologically relevant window. Collectively, these results have contributed to new ways of interfacing functional nanomaterials with the cellular environment.
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Evans, Nicholas David. "Fluorescence-based non-invasive glucose sensing for diabetes." Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416007.
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Cabell, Larry Allen. "Chemosensors and competition sensing assays /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Frey, Eric W. "Fluorescence-Based Calcium Ion Sensing at High Hydrostatic Pressures." Miami University Honors Theses / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=muhonors1209176599.
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Blagoi, Gabriela. "Fluorescence resonance energy transfer (FRET) based sensors for bioanalysis." ScholarWorks@UNO, 2004. http://louisdl.louislibraries.org/u?/NOD,146.
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Thesis (Ph. D.)--University of New Orleans, 2004.Title from electronic submission form. "A dissertation ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry."--Dissertation t.p. Vita. Includes bibliographical references.
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Kuwana, Eddy. "Measurement and model assessment of fluorescence lifetime sensing in multiply scattering media." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2209.
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The generation and propagation of fluorescence light within biological tissue offers the potential for biomedical diagnostics and analyte sensing. Arising from an exogenous fluorescent dye injected as a contrast agent or immobilized in a polymer implant, the fluorescent decay kinetics can be sensitive to the tissue??s biochemical environment, providing quantitative in vivo information of the confined tissue site. The impact of light propagation and decay kinetics upon the measured signals is important for consideration, simply because tissue scatters light, giving rise to nanosecond photon time-of-flights that are comparable to fluorescence relaxation kinetics. The goal of this study is to develop a time-dependent model describing (i) the generation of fluorescence from dyes exhibiting multi-exponential or more complex kinetics and (ii) its propagation in scattering media. In the preliminary study, fluorescence lifetime spectroscopy is investigated in tissue-like scattering solution. Two fluorescent dyes, 3,3-diethylthiatricarbocyanine iodide (DTTCI) and Indocynanine Green (ICG), which exhibit distinctly different lifetimes and each exhibits single-exponential decay kinetics, were employed. Measurements of phase-modulation as a function of modulation frequency were made at varying concentration ratios of the two dyes to experimentally simulate fluorescence multi-exponential decay kinetics in non-scattering and scattering solutions. The results suggest that frequency-domain measurements of fluorescent decay kinetics along with models of light propagation may be enhanced by scatter in order to probe kinetics more sensitively than in non-scattering solutions. The next study involved fluorescence lifetime sensing in scattering and non-scattering solutions with a pH sensitive dye, Carboxy Seminaphthofluorescein-1 (C-SNAFL-1), which is known to exhibit multi-exponential decay kinetics. The results demonstrate accurate pH sensing in scattering solution via fluorescence kinetics using a simplified propagation model incorporating an average lifetime. Finally, fluorescence lifetime sensing in immobilized systems were investigated. C-SNAFL-1 was immobilized in poly(ethylene glycol) (PEG) microparticles that were immersed in buffered polystyrene solutions. The results demonstrate the ability to perform pH sensing with fluorescence lifetime without the confounding effect of fluorophore loading or the use of 'reference' measurement within multiply scattering systems. In addition, the stability of the immobilized fluorescence sensor and the reliability of fluorescence lifetime measurement verify the prospect of this technology for implantable purposes.
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Williams, Alice E. "Time resolved fluorescence and pH sensing studies of electropolymerised 5-substituted indoles." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/14666.
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In this thesis electropolymerised samples of the 5-cyanoindole and 5-bromoindole were studied. Steady state fluorescence and Time Correlated Single Photon Counting experiments were performed on solutions in ethanol of both types of polymer, and potentiometric experiments to ascertain the pH sensing ability of 5-cyanoindole solid films were carried out. The potential of rotating disc electrodes modified with thick (1.37μm) and thin (0.49μm) films 5-cyanoindole polymer were found to respond to changes in electrolyte pH linearly with a near-Nernstian slope, which is indicative of a promising pH sensing material. The response was independent of direction of pH change and sustainable over a time period of at least a week. The thin film shored promise as a good fast response pH sensor. Steady State (SS) fluorescence spectroscopy experiments carried out on solutions of electropolymerised 5-cyanoindole in ethanol at room temperature have shown that, when exciting at short wavelength the trimer chromophore gives the most intense emission at short wavelength, with no emission seen at longer wavelengths, and no noticeable difference between samples produced to produce trimer-rich and more extensively linked films. Exciting at longer wavelength a slight difference between the emission intensities of higher polymer and higher trimer content films was observed. Time Correlated Single Photon Counting (TCSPC) experiments were carried out at excitation wavelengths 360nm and 450nm and it was seen that the free trimer chromophore was the dominant contributor to the excited state population at all wavelengths. SS experiments were carried out on solutions of electropolymerised 5-bromoindole in ethanol and, consistent with previous work, it was seen that higher intensity of emission was seen in the polymeric region at longer emission wavelength. Additionally a marked difference was seen between higher and lower polymer content films.
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Kateklum, Rutjaphan. "Fiber optic fluorescence pH sensing for biomedical applications : theoretical and experimental studies." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD048.
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Les fonctions organiques du corps humain sont liées à des constants biologiques. Variations de ces constantes induisent divers états pathologiques. Parmi ces constantes, le pH constitue le cœur de ces travaux de thèse. Chez les êtres vivants, les fonctions biologiques dépendent de constant acides ou alcalines. En fait, l’action d’une protéine dépend du pH du milieu environnant. Une valeur inadéquate du pH rend les protéines inactives ce qui est délétère pour l’organisme. Il existe donc un besoin pour des capteurs de pH qui puissant être utilisés dans le corps humain pour des applications cliniques (échelle macroscopique), sur des cellules en culture pour des recherches en biologie (échelle mesoscopique) et pour étudier les échanges ioniques au niveau des membranes cellulaires pour des travaux plus fondamentaux (échelle microscopique). Parmi le large éventail de technologies potentiellement candidates pour ces applications, la mesure de pH par fibre optique exploitant la fluorescence permet d’être adaptée aux trois échelles dimensionnelles susnommées. Ce manuscrit de thèse adresse des contraintes par l’étude de capteurs fluorescents à fibre optique utilisant deux types d’indicateur de pH: les SNARF et la fluorescéine. En parallèle de ces développements expérimentaux, des descriptions mathématiques des propriétés de fluorescence de ces deux indicateurs sont proposées. Ces descriptions permettent de progresser vers une mesure du pH sans calibrationOrganic functions of the human body are linked to biological constants. Variations of these constants induce pathological troubles. Among these constants, the pH is the central subject of this PhD work. In living beings, biological functions are related to either acid or alkaline constants. Indeed, the action of a protein depends on the surrounding pH. An inadequate value of the pH makes the proteins non active which is deleterious for the organism. There exist a need for pH sensors which can be used in the human body for clinical applications (macroscopic scale), on cells in culture for biology researches (mesoscopic scale) or at a cell membrane level for more fundamental studies (microscopic scale). Among the wide range of technologies potentially useful for these applications, fiber optic fluorescence pH sensing offers the possibility to be adapted to the three above mentioned dimensional scales. This PhD dissertation addresses these constraints by studying fluorescence fiber optics pH sensors using two kind of pH indicators: SNARF and fluorescein. Together with these experimental studies, mathematical descriptions of the fluorescence properties of these indicators are proposed. They allow progressing towards calibration free pH sensing
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Dalzell, Craig John. "Two-photon excited fluorescence and applications in distributed optical fibre temperature sensing." Thesis, University of Strathclyde, 2011. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=17062.
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Yushchenko, Dmytro. "Synthesis, spectroscopic study and application of ratiometric fluorescent dyes for apoptosis sensing and protein labelling." Strasbourg 1, 2007. http://www.theses.fr/2007STR13070.
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Bakker, Jimmy W. P. "New methodology for optical sensing and analysis." Licentiate thesis, Linköping University, Linköping University, Applied Optics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5670.
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This thesis describes the research I have done, and partly will do, during my time as a PhD student in the laboratory of Applied Optics at Linköping University. Due to circumstances beyond the scope of this book, this incorporates three quite different projects. The first two, involving gas sensing and measuring on paper with ellipsometry, have been discontinued, whereas the third one, measuring fluorescence with a computer screen and web camera, is in full progress and will be until I complete my studies.
Thus the purpose of this work also has several aspects. Partly, it describes performed research and its results, as well as theoretical background. On the other hand, it provides practical and theoretical background necessary for future work. While the three projects are truly quite different, each of them has certain things in common with each of the other. This is certainly also true for the necessary theory. Two of them involve spectroscopic ellipsometry, for example, while another pair needs knowledge of color theory, etc. This makes it impossible to separate the projects, despite of their differences. Hopefully, these links between the different projects, connecting the different chapters, will make this work whole and consistent in its own way.
Report code: LiU-TEK-LIC-200 4-19. On the day of the public defence the status of article I was: In press and the status of article III was: Manuscript and has a new title. The old title was Computer screen photo-assisted spectroscopic fluorimetry.
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Pham, Xuan Qui. "New Optical Sensing for the Detection of Toxic Cations : Cesium, Uranyl and Arsenic." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLN005.
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Ce travail concerne la synthèse, les études des propriétés photophysiques et de complexation des molécules fluorescentes pour la détection sélective de cations toxiques tels que le césium, l'uranyle et l'arsenic. Tout d'abord, deux nouveaux capteurs fluorescents pour le césium, Calix-COU-P et Calix-COU-Benz-CN, comportant le Calix[4]arène-couronne-6 et le fluorophore coumarine ont été synthétisés avec succès. En ce qui concerne le Calix-COU-P, une forte exaltation de fluorescence et un déplacement bathochrome d'absorption ont été observés en présence de césium dans l'eau. Une très bonne limite de détection (0,77 μM) ainsi qu'une excellente sélectivité vis-à-vis du césium ont été observées, démontrant que Calix-COU-P pourrait être un capteur exceptionnel pour la détection de césium dans l'eau. Calix-COU-Benz-CN possède quant à lui des propriétés photophysiques prometteuses dans un milieu partiellement aqueux avec des bandes d'absorption et de fluorescence intenses en visible grâce à la présence des groupements benzothiazole et cyano. L'addition de césium conduit aux déplacements ver le bleu des spectres d'absorption et une augmentation de l'intensité de fluorescence. L'étude de la cinétique de complexation entre Calix-COU-Benz-CN et Cs+ par la technique « stopped-flow » a montré une cinétique rapide à faibles concentrations de cations et une cinétique plus longue à des concentrations élevées (> 10 mM). Calix-COU-Benz-CN a ensuite été incorporé dans un dispositif microfluidique. Une courbe d'étalonnage qui représente l'intensité de fluorescence en fonction de la concentration du césium montre une valeur de limite de détection de l’ordre de 2,0 μM. Deux composés analogues contenant la même entité complexante Calix[4]arène-couronne-6 ont été également synthétisés et greffés sur des nanoparticules magnétiques afin d’obtenir un matériau fonctionnalisé pour la décontamination de l’eau contenant le césium radioactif. L'étude préliminaire montre que les nanoparticules fonctionnalisées pourraient capter efficacement une quantité très faible du césium dans l’eau contaminée. Par la suite, en vue de développer des capteurs pour l’uranyle, une série de dérivés de salicylaldéhyde-azine ont été synthétisés et caractérisés. Leurs propriétés d'émission induites par l'agrégation (AIE) ont été étudiées. Dans un mélange eau/acétonitrile, les composés U1 et U2 présentent une forte fluorescence lors de l'agrégation tandis que le composé U3 ne présente pas cet effet AIE dans la même condition. Grâce aux sites de complexation contenant des atomes d’oxygène et d'azote, ces molécules présentent une complexation efficace avec les ions uranyle et induire une extinction de la fluorescence. Dans notre étude, il était intéressant de noter la présence d’uranyle conduit à une destruction de l'agrégation, en particulier pour la molécule U2 dans un mélange eau / acétonitrile 60:40. L’extinction de l’émission a été expliquée par des processus de destruction d'agrégats émissifs lors de la complexation avec le cation. Le mécanisme proposé a été validé par des expériences de diffusion dynamique de la lumière et de microscopie électronique à balayage. Le composé U2 présente une bonne sélectivité vis-à-vis de l'uranyle en présence des lanthanides et des autres cations compétitifs. Le capteur permet la détection de concentrations de l’ordre ppb en uranyle. Enfin, la synthèse et l'étude de nouveaux capteurs pour la détection de l’arsenic ont également été discutées. Une série de capteurs fluorescents portant l’entité complexante cystéine a été synthétisée et leurs propriétés complexantes pour l'arsenic ont été étudiées. De plus, des nanoparticules d'or modifiées par la cystéine, le glutathion et le dithiothréitol ont été synthétisées. La complexation de l'ion arsenic avec ces nanoparticules a été étudiée et discutée. Une perspective sur le développement de nouveaux capteurs pour l’arsenic a été proposéeThis thesis focuses on the synthesis, photophysical and complexation studies of fluorescent molecules for the selective detection of toxic cations such as cesium, uranyl and arsenic. Firstly, two new fluorescent sensors Calix-COU-P and Calix-COU-Benz-CN for cesium cations based on Calix[4]arene-crown-6 and coumarin fluorophore were successfully synthesized. For Calix-COU-P, a remarkable fluorescence enhancement and a red shift in absorption were observed due to the complexation with cesium cation in water. Good detection limits (0.77 µM) together with an excellent selectivity towards cesium were observed, demonstrating that Calix-COU-P could be an outstanding sensor for the detection of cesium cation in water. Calix-COU-Benz-CN possesses exceptional photophysical properties in an organoaqueous solution with intense visible absorption and emission bands thanks to benzothiazole and cyano groups. The addition of cesium cation to Calix-COU-Benz-CN offered noticeable blue shifts of the absorption spectra and considerably enhanced the emission intensity. The kinetic study of the complexation between Calix-COU-Benz-CN and Cs+ by stopped-flow experiments showed a rapid kinetic at small concentrations of cations and a lower kinetic at higher concentrations (> 10 mM). Calix-COU-Benz-CN was then incorporated into a microfluidic device. The voltage signals, which are proportional to the fluorescence intensity, were monitored continuously at various cesium concentrations. A calibration curve which represents the fluorescence intensity as a function of cesium cation concentration gives a value of detection limit up to 2.0 µM. This value is only slightly higher than the detection limit obtained by fluorescence titration (1.67 µM), which suggests that the microfluidic device is capable to provide good sensitivity towards targeted ion for real-world applications. Furthermore, two analogous compounds Calix-DOP and Calix-DOP-P containing the same complexing entity were also synthesized and grafted onto magnetic nanoparticles in order to obtain a functionalized material for the decontamination of the water containing radioactive cesium. The preliminary study shows that functionalized nanoparticles could efficiently sequester cesium ions from contaminated water.Afterward, to develop new sensors for the detection of uranyl cations, a series of salicylaldehyde azine derivatives have been synthesized and characterized. Their aggregation induced emission properties were studied. In water/acetonitrile solvent, compounds U1 and U2 exhibited strong fluorescence upon aggregation while compound U3 did not aggregate and stayed in solution as well-dispersed molecules. Owning to oxygen and nitrogen binding sites, the molecules could complex uranyl ions and induced fluorescence quenching. In our study, it was interesting to understand that the effect of uranyl was somewhat more destructive rather than constructive to the aggregation. The most obvious quenching effect was observed for the aggregates of U2 in water/acetonitrile 60:40. The emission quenching was explained by aggregate-breaking processes, that the emitting aggregates could be destroyed by the complexation with uranyl cation. The proposed mechanism was further supported by dynamic light scattering and scanning electron microscope experiments. Compound U2 showed good selectivity towards uranyl over lanthanides and other common cations. The sensor could detect uranyl up to ppb scale.Finally, synthesis and studies of new sensors for the detection of arsenic ion were also discussed. A series of fluorescent sensors bearing cysteine moiety was synthesized and their complexing properties for arsenic were studied. Furthermore, gold nanoparticles which were modified by cysteine, glutathione and dithiothreitol were synthesized. The complexation of arsenic ion with these modified gold nanoparticles was studied and discussed. A perspective for further development of arsenic sensors was proposed
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Matthews, Alison Mary. "High resolution spectral remote sensing of phytoplankton in the coastal zone." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241275.
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Fuchs, Eran 1963. "Underwater in situ optical measurements and coral fluorescence for shallow water remote sensing." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38189.
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Shuai, Yun. "Improved On-chip Fluorescence Detection and Oxygen Sensing using Organic Thin Film Devices." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1243306326.
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Yang, Wanggui. "Molecular recognition of [pi]-conjugated fluorophores for supramolecular nanostructures and bio-sensing applications." HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1402.
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Inal, Sahika. "Responsive polymers for optical sensing applications." Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2014/7080/.
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LCST-type synthetic thermoresponsive polymers can reversibly respond to certain stimuli in aqueous media with a massive change of their physical state. When fluorophores, that are sensitive to such changes, are incorporated into the polymeric structure, the response can be translated into a fluorescence signal. Based on this idea, this thesis presents sensing schemes which transduce the stimuli-induced variations in the solubility of polymer chains with covalently-bound fluorophores into a well-detectable fluorescence output. Benefiting from the principles of different photophysical phenomena, i.e. of fluorescence resonance energy transfer and solvatochromism, such fluorescent copolymers enabled monitoring of stimuli such as the solution temperature and ionic strength, but also of association/disassociation mechanisms with other macromolecules or of biochemical binding events through remarkable changes in their fluorescence properties. For instance, an aqueous ratiometric dual sensor for temperature and salts was developed, relying on the delicate supramolecular assembly of a thermoresponsive copolymer with a thiophene-based conjugated polyelectrolyte. Alternatively, by taking advantage of the sensitivity of solvatochromic fluorophores, an increase in solution temperature or the presence of analytes was signaled as an enhancement of the fluorescence intensity. A simultaneous use of the sensitivity of chains towards the temperature and a specific antibody allowed monitoring of more complex phenomena such as competitive binding of analytes.
The use of different thermoresponsive polymers, namely poly(N-isopropylacrylamide) and poly(meth)acrylates bearing oligo(ethylene glycol) side chains, revealed that the responsive polymers differed widely in their ability to perform a particular sensing function. In order to address questions regarding the impact of the chemical structure of the host polymer on the sensing performance, the macromolecular assembly behavior below and above the phase transition temperature was evaluated by a combination of fluorescence and light scattering methods. It was found that although the temperature-triggered changes in the macroscopic absorption characteristics were similar for these polymers, properties such as the degree of hydration or the extent of interchain aggregations differed substantially. Therefore, in addition to the demonstration of strategies for fluorescence-based sensing with thermoresponsive polymers, this work highlights the role of the chemical structure of the two popular thermoresponsive polymers on the fluorescence response. The results are fundamentally important for the rational choice of polymeric materials for a specific sensing strategy.Als Reaktion auf bestimmte äußere Stimuli ändern bestimmte wasserlösliche Polymere reversibel ihren physikalischen Zustand. Dieser Vorgang kann mithilfe von Fluorophoren, die in die Polymerstrukturen eingebaut werden und deren Fluoreszenzeigenschaften vom Polymer¬zustand abhängen, detektiert werden. Diese Idee ist der Ausgangspunkt der vorliegenden Arbeit, die sich damit beschäftigt, wie äußerlich induzierte Änderungen der Löslichkeit solcher Polymere mit kovalent gebundenen Fluorophoren in Wasser in ein deutlich messbares Fluoreszenzsignal übersetzt werden können. Dazu werden photophysikalische Phänomene wie Fluoreszenz-Resonanz¬energie¬transfer und Solvatochromie ausgenutzt. In Kombination mit einem responsiven Polymergerüst wird es möglich, verschiedene Stimuli wie Lösungs¬temperatur oder Ionenstärke, oder auch Assoziation-Dissoziation Reaktionen mit anderen Makromolekülen oder biochemische Bindungs¬reaktionen über die Änderung von Fluorezenz¬farbe bzw. –Intensität autonom mit bloßem Auge zu detektieren. Unter anderem wurde ein wässriger ratiometrischer Temperatur- und Salzsensor entwickelt, der auf der komplexen supramolekularen Struktur eines thermoresponsiven Copolymers und eines thiophenbasierten konjugierten Polyelektrolyts beruht. Die Anbindung solvato¬chromer Fluorophore erlaubte den empfindlichen Nachweis einer Temperatur¬änderung oder des Vorhandenseins von Analyten. Komplexere Phänomene wie das kompetitive Anbinden von Analyten ließen sich hochempfindlich steuern und auslesen, indem gleichzeitig die Sensitivität dieser Polymeren gegenüber der Temperatur und spezifischen Antikörpern ausgenutzt wurde. Überraschenderweise wiesen die hier untersuchten thermoresponsiven Polymere wie poly-N-isopropylacrylamid (pNIPAm) oder poly-Oligoethylenglykolmethacrylate (pOEGMA) große Unterschiede bzgl. ihrer responsiven optischen Eigenschaften auf. Dies erforderte eine ausführliche Charakterisierung des Fluoreszenz- und Aggregationsverhaltens, unter- und oberhalb des Phasenübergangs, im Bezug auf die chemische Struktur. Ein Ergebnis war, dass alle drei Polymertypen sehr ähnliche temperaturabhängige makroskopische Absorptionseigenschaften aufweisen, während sich die Eigenschaften auf molekularer Ebene, wie der Hydratisierungsgrad oder die intermolekulare Polymerkettenaggregation, bei diesen Polymeren sehr unterschiedlich. Diese Arbeit zeigt damit anhand zweier sehr etablierter thermoresponsiver Polymere, nämlich pNIPAm und pOEGMA, das die chemische Struktur entscheidend für den Einsatz dieser Polymere in fluoreszenzbasierten Sensoren ist. Diese Ergebnisse haben große Bedeutung für die gezielte Entwicklung von Polymermaterialien für fluoreszenzbasierte Assays.
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Upamali, Karasinghe A. Nadeeka. "Carbazole-Based, Self-Assembled, Π-Conjugated Systems As Fluorescent Micro And Nanomaterials - Synthesis, Photophysical Properties, Emission Enhancement And Chemical Sensing." Bowling Green State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1323099511.
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Zarco-Tejada, Pablo J. "Hyperspectral remote sensing of closed forest canopies, estimation of chlorophyll fluorescence and pigment content." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ59161.pdf.
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Sakakibara, Reyu. "Electrochemical modulation of fluorescence of nitrogen vacancy centers in nanodiamonds for voltage sensing applications." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97766.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 105-112).
The nitrogen vacancy (NV) color center in diamond has been used to sense environmental variables such as temperature and electric and magnetic fields. Most sensing protocols depend on the optically detectable magnetic resonance of the negatively charged NV- spin state. As such, fluctuations in the NV charge state present a challenge for NV- spin-based sensing. This thesis discusses the electrochemical modulation of NV charge state and fluorescence as the basis for an alternative sensing scheme. An externally applied electrochemical potential shifts the occupation probabilities of the NV in each charge state, which manifest as changes in NV fluorescence intensity and emission spectra. In this thesis, the voltage dependence of fluorescence in high pressure high temperature nanodiamonds is demonstrated in an electrochemical cell. Following this, the mechanisms for NV response to externally applied electrical bias are investigated in other electrochemical cell morphologies, capacitors, and interdigitated electrode arrays. Finally, a design of an optical microscope setup for future studies of NV sensing in nanodiamond is outlined.
by Reyu Sakakibara.
S.M.
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Tyndall, David. "CMOS system for high throughput fluorescence lifetime sensing using time correlated single photon counting." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/12238.
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Fluorescence lifetime sensing using time correlated single photon counting (TCSPC) is a key analytical tool for molecular and cell biology research, medical diagnosis and pharmacological development. However, commercially available TCSPC equipment is bulky, expensive and power hungry, typically requiring iterative software post-processing to calculate the fluorescence lifetime. Furthermore, the technique is restrictively slow due to a low photon throughput limit which is necessary to avoid distortions caused by TCSPC pile-up. An investigation into CMOS compatible multimodule architectures to miniaturise the standard TCSPC set up, allow an increase in photon throughput by overcoming the TCSPC pile-up limit, and provide fluorescence lifetime calculations in real-time is presented. The investigation verifies the operation of the architectures and leads to the selection of optimal parameters for the number of detectors and timing channels required to overcome the TCSPC pile-up limit by at least an order of magnitude. The parameters are used to implement a low power miniaturised sensor in a 130 nm CMOS process, combining single photon detection, multiple channel timing and embedded pre-processing of the fluorescence lifetime, all within a silicon area of < 2 mm2. Single photon detection is achieved using an array of single photon avalanche diodes (SPADs) arranged in a digital silicon photomultiplier (SiPM) architecture with a 10 % fill-factor and a compressed 250 ps output pulse, which provides a photon throughput of > 700 MHz. An array of time-interleaved time-to-digital converters (TI-TDCs) with 50 ps resolution and no processing dead-time records up to eight photon events during each excitation period, significantly reducing the effect of TCSPC pile-up. The TCSPC data is then processed using an embedded centre-of-mass method (CMM) pre-calculation to produce single exponential fluorescence lifetime estimations in real-time. The combination of high photon throughput and real-time calculation enables advances in applications such as fluorescence lifetime imaging microscopy (FLIM) and time domain fluorescence lifetime activated cell sorting. To demonstrate this, the device is validated in practical bulk sample fluorescence lifetime, FLIM and simulated flow based experiments. Photon throughputs in excess of the excitation frequency are demonstrated for a range of organic and inorganic fluorophores for minimal error in lifetime calculation by CMM (< 5 %).
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Koutnik, Petr. "First Supramolecular Fluorescence-Based Assay for Carbonic Anhydrase Inhibitors." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1471261858.
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Campbell, Ian. "Development of optical based characterisation and detection methods for quantitative and qualitative assessment of phytoplankton in their natural environment." Thesis, Robert Gordon University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325446.
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Akdeniz, Ali. "Sensing of Enantiomeric Excess in Chiral Carboxylates." Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1465223828.
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Poon, Chung Yan. "Nanoparticles assisted disease biomarkers sensing by microscopic and spectrometric methods." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/300.
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Nanoparticles has drawn attention in the past few decades for their large surface area-to-volume ratio, unique optical property, fast mass transportation and etc. They are widely applied in biomedical field as they are excellent signal transducers. Among all detection approaches, fluorescence detection, especially fluorescence resonance energy transfer (FRET), is one of the most popular approaches for their great convenience. In the first detection scheme, a well-designed nanoprobe was utilized for direct trypsin quantification. Herein, a graphene quantum dot (GQD) applied as a donor while a coumarin derivative, CMR2, acted as an acceptor. Moreover, bovine serum albumin (BSA), as a protein model, was not only considered as a linker for the donor-acceptor pair, but also a fluorescence enhancer of the quantum dots and CMR2. In the presence of trypsin, BSA was digested, thus, the FRET system was destroyed. Consequently, the emission peak of the donor was regenerated while the emission of the acceptor was reduced. The trypsin was quantified by a ratiometric measurement for two emission peaks. The detection limit of trypsin was 0.7 g/mL, which is 0.008-fold of the average trypsin level in acute pancreatitis patient's urine. Moreover, the approach was proved to be highly selective, suggesting a high potential for fast and low cost clinical screening. On the other hand, the optical property of nanoparticle has captured a great attention as its light scattering is highly sensitive to local dielectric environment. Two light scattering based detection approaches were demonstrated, including simple counting method and plasmonic scattering enhancement method. For simple counting method, antibody modified nanoparticle was applied to target antigen, providing a sensitive but direct approach for cancer biomarkers quantification. As a proof of concept, prostate-specific antigen (PSA) was chosen as an example. Antibody-conjugated silver nanoparticles (AgNP-Ab) were served as the probe to capture PSA, forming AgNP-Ab-PSA complexes. Since the number of complexes was corresponding to the amount of PSA, the antigen was quantified by counting the number of silver nanoparticle under dark field microscopy (DFM) coupled with charge-coupled device (CCD) camera. The detection limit of 9 pM of this assay was well below the PSA threshold of prostate cancer patient, suggested the feasibility of our assay in diagnosis application. Besides counting of nanoparticle, the scattering intensity of nanoparticle is also informative. In the third assay, immobilized capture antibody-conjugated gold nanoparticles (AuNP-Abcapture) were firstly utilized in capturing the target analyte, followed by the introduction of strong scattering detection antibody-conjugated silver nanoparticles (AgNP-Abdetection). In the presence of the corresponding antigen, the two metallic probes sandwiched the antigen and stayed at close proximity, resulting a strong plasmonic coupling effect of those nanoparticles. Consequently, the scattering intensity of gold nanoprobe was greatly enhanced. The antigen was quantified by measuring the intensity change before and after the immunoreaction. To demonstrate the high flexibility of this assay, several antigens including carcinoembryonic antigen (CEA), PSA and alpha fetoprotein (AFP) were quantified with this method, giving detection limit at 1.7 pM, 3.3 pM and 5.9 pM respectively, which were much lower than their cut-off levels of corresponding diseases. Detections of CEA, PSA and AFP in real sample were demonstrated, suggesting a high potential in clinical application.
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Xu, Di. "Multifunctional cyanine fluorophores for cellular imaging and sensing in vivo and beta-amyloid imaging and aggregation inhibition." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/382.
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The development of facile and reliable methods to image and detect important biomolecules has drawn considerable attention owing to their potential applications in clinical, bioanalytical and forensic analysis. One-photon microscopy (OPM) has traditionally been used in cell biology research. However, probes based on OPM are associated with shortcomings including photobleaching, cell damage, and intracellular autofluorescence interference. Many researchers are seeking better tools to overcome these obstacles. Two-photon microscopy (TPM) is a convenient and powerful tool to explore the intracellular environment and provides the opportunity to overcome the abovementioned obstacles. Probes based on TPM have become important for bioimaging and sensing because of their low photodamage, reduced fluorescence interference, and better tissue penetration depth. With the development of fluorescence molecules in recent decades, a wide range of organic fluorescence probes based on TPM has been rapidly developed and used in biomedicine and bioimaging. Cyanine dye, one of the classic synthetic dyes, continues to be used in many fields, especially in bio-related applications, owing to its ability to interact with biomolecules through non-covalent and electrostatic bonds. Based on cyanine models, we designed a series of structural modifications of cyanine fluorophores used as two-photon (TP) probes to detect and image the intracellular environment in which new cyanine compounds, namely SLSO3, SLCOOH-Pr, F-SLOH, SLOH, Me-SLM, SLE, SAM, SAOH, SLG, F-SPG, SLOH-Pr, SLAD, F-SLAD, Me-SLG, SLNA, SLAD-Pr, SLCOOH, SLAce, SLM, SPC, SIOH, PSIOH, DMA-SLOH, DBA-SLOH, DPA-SLM, GBPM, HBBM, HBLM, SBM, SIBM, SIM, PLOH, and PTM, was successfully synthesized. All of these newly designed compounds were characterized with 1H NMR, 13C NMR, and HRMS and found to show good agreement with the desired structures. To our surprise, some of the novel cyanine molecules were also able to detect and image amyloid-β (Aβ) peptide species and showed excellent biological properties including neuroprotective effects against the cytotoxicity induced by different forms of Aβ species, blood-brain barrier permeability, and high in vivo stability. The photophysical and biological properties of these newly synthesized compounds included optical properties such as UV-vis absorption, emission, fluorescence quantum yield in different solvents, dissociation constant determined by fluorescence titration, and circular dichroism spectroscopy, cytotoxicity assay, neuroprotection, and inhibition of Aβ aggregation were investigated.
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Winkler, Amy. "OPTICAL METHODS FOR MOLECULAR SENSING: SUPPLEMENTING IMAGING OF TISSUE MICROSTRUCTURE WITH MOLECULAR INFORMATION." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195176.
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More and more researchers and clinicians are looking to molecular sensing to predict how cells will behave, seeking the answers to questions like "will these tumor cells become malignant?" or "how will these cells respond to chemotherapy?" Optical methods are attractive for answering these questions because optical radiation is safer and less expensive than alternative methods, such as CT which uses X-ray radiation, PET/SPECT which use gamma radiation, or MRI which is expensive and only available in a hospital setting. In this dissertation, three distinct optical methods are explored to detect at the molecular level: optical coherence tomography (OCT), laser-induced fluorescence (LIF), and optical polarimetry. OCT has the capability to simultaneously capture anatomical information as well as molecular information using targeted contrast agents such as gold nanoshells. LIF is less useful for capturing anatomical information, but it can achieve significantly better molecular sensitivity with the use of targeted fluorescent dyes. Optical polarimetry has potential to detect the concentration of helical molecules, such as glucose. All of these methods are noninvasive or minimally invasive.The work is organized into four specific aims. The first is the design and implementation of a fast, high resolution, endoscopic OCT system to facilitate minimally invasive mouse colon imaging. The second aim is to demonstrate the utility of this system for automatically identifying tumor lesions based on tissue microstructure. The third is to demonstrate the use of contrast agents to detect molecular expression using OCT and LIF. The last aim is to demonstrate a new method based on optical polarimetry for noninvasive glucose sensing.
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Renard, Laëtitia. "Nanostructured tin-based materials : sensing and optical applications." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14183/document.
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Des matériaux hybrides de classe II ont été préparés à partir de précurseurs bis(tripropynylstannylés). Deux familles de précurseurs sol-gel incluant des espaceurs hydrocarbonés et thiophénique ont été obtenues et conduisent à des matériaux hybrides auto-organisés où les plans d’oxyde sont séparés par les espaceurs organiques. Ainsi l’espaceur rigide a donné lieu à une structure pseudo-lamellaire montrant une bande d’émission monomère avec un assez faible décalage vers le rouge par rapport à l'émission des précurseurs en solution. En revanche, alors que les xérogels thiényle plus désordonnés conduisent à une large émission caractéristique de la formation d’excimères ou de dimères. Par ailleurs, des films minces contenant les espaceurs alkylène et arylalkylène ont été préparés et ont montré une morphologie "pseudoparticulaire" poreuse et un ordre à courte distance contenant des réseaux SnOx. De façon inattendue, ces films minces hybrides détectent le dihydrogène dès une température de 50 °C dans la gamme 200-10000 ppm. A partir de ces films hybrides minces, le dioxyde d'étain cristallin (SnO2) a été préparé par un post-traitement thermique. Comme prévu, ces films SnO2 cassitérite détectent le dihydrogène et, dans une moindre mesure le monoxyde de carbone avec une température optimale de fonctionnement comprise entre 300 et 350 °CClass II hybrid materials were prepared from ditin hexaalkynides. Two families of precursors, including either hydrocarbon or oligothiophene-based spacers, were obtained and led by the sol-gel process to self-assembled organotin-based hybrid materials made of planes of oxide separated by organic bridges. Thus, the rigid thienyl spacer gave rise to a “pseudo-lamellar” structure that showed a monomer emission band with a rather small red-shift compared with to the emission of the precursor in solution. However more disordered thienyl xerogels led to broad emission features assigned to excimer or dimer formation. Moreover, thin films containing alkylene- and arylalkylene bridged have been prepared and showed a “pseudoparticulate” porous morphology and a short-range hierarchical order in the organic-inorganic SnOx pseudoparticles. Unexpectedly these hybrid thin films detect hydrogen gas at a temperature as low as 50 °C at the 200-10000 ppm level. From these hybrid thin films, crystalline tin dioxide (SnO2) were prepared by a thermal post-treatment. As expected, cassiterite SnO2 films detected H2 and to a less extent CO with a best operating temperature comprised between 300 and 350 °C
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Abdul-Majeed, Shakila. "Regulation of Fluid-Shear Stress Sensing by Mechanosensory Primary Cilia." University of Toledo Health Science Campus / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=mco1310083302.
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Yang, Xiaochuan. "Design and Synthesis of Boronic Acid-Modified Nucleotides for Fluorescent Sensing and Cell Imaging." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/chemistry_diss/39.
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With the rapidly increasing interest in the field of glycomics, which is the comprehensive study of the roles carbohydrates play in a living system, urgent need for developing quick and highly selective carbohydrate sensors is growing. The boronic acid group, with its electron-deficient structure (6 valence electrons with an open shell), acts as a Lewis acid with high intrinsic affinity towards Lewis bases such as fluoride, cyanide and hydroxyl groups. Specifically, formation of a 5- or 6- membered ring between the boronic acid moiety and a1,2- or 1,3-diol in aqueous solution has been fully explored as a strategy of carbohydrate sensor design. Along this line, those binders were termed as ¡°boronolectins¡± because of their similar functions as lectins. One challenge in developing boronic acid-based carbohydrate sensors is to enhance the discriminating ability among various carbohydrate analytes with diverse building blocks and complex linkage patterns. One approach is using polypeptide or oligonucleotide as a backbone or scaffold with functionalized boronic acid moiety to create a molecular library, and then selecting binders with favorable properties. The work presented here includes three general research parts: synthesis of a naphthalimide-based boronic acid-conjugated thymidine triphosphate (NB-TTP), fluorescence property studies of NB-TTP incorporated DNA (NB-DNA), and cellular imaging studies using NB-TTP: 1) 4-Amino-1,4-naphthalimide (Nap) was chosen as the fluorophore because of its relatively long excitation and emission wavelengths, and stability. The synthesis of naphthalimide-based boronic acid (NB) followed similar route as previously published work. Tethering of boronic acid moiety and TTP was accomplished through Cu(I)-catalyzed azide-alkyne cyclization (CuAAC), known as click chemistry. The synthesized NB-TTP showed fluorescence enhancements at long wavelength (¦Ëem: 540 nm) upon sugar addition. 2) NB-TTP was incorporated into DNA through Klenow fragment-catalyzed primer extension reactions. Different DNA sequences were designed with varying number and spacing for NB-TTP incorporation. The preliminary study provided certain insight into several factors that affect the fluorescent properties of different NB -DNA. 3) NB-TTP was added into Hela cell culture medium to study its cell imaging properties. With the observation under fluorescent microscope, it was demonstrated that NB-TTP showed good cell membrane permeability and significant accumulation in cell nucleus.
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Rhoul, Camill. "Simulation de la fluorescence de la végétation mesurée depuis une orbite géostationnaire." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX097/document.
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Le travail de cette thèse porte sur l’étude de la télédétection de la fluorescence chlorophyllienne avec un instrument imageur passif depuis une orbite géostationnaire pour le suivi de l’état physiologique de la végétation. Le concept instrumental est étudié théoriquement pour aboutir à la création d’uninstrument et à sa validation. La possibilité de mesurer des cycles diurnes de la fluorescence végétale depuis une orbite géostationnaire est évaluée à l’aide de simulations qui permettent de dresser les spécifications d’un instrument spatial.L’instrument imageur passif mesure dans la bande O 2 -A d’absorption atmosphérique. Il utilise une roue à filtres interférentiels dont la fonction de transmittance varie avec l’angle d’incidence des rayons les traversant. L’étude théorique a permis d’optimiser le placement spectral des filtres en vuede minimiser l’incertitude liée à la mesure de fluorescence.Grâce à la comparaison des mesures de l’instrument imageur avec d’autres instrument de mesure de la fluorescence, l’instrument et son concept instrumental ont été validés. Néanmoins, à cause d’effets de structure de la végétation intervenant sur le transfert radiatif de la fluorescence et de la lumière solaire au sein du couvert végétal, ces mesures ont confirmé la difficulté d’estimer le rendement de fluorescence de la végétation à partir des flux de fluorescence mesurés.Une étude théorique menée grâce à une modélisation du transfert radiatif de la fluorescence dans le couvert végétal jusqu’au capteur a permis d’expliquer la difficulté à retrouver le rendement de fluorescence à partir des flux. Cette étude a mis en avant l’accessibilité du rendement pour des couverts à fortedensité de feuilles et lorsque la distribution de l’orientation des feuilles est centrée sur l’horizontale.Cette modélisation a été étendue pour simuler des mesures spatiales dans le but d’étudier la possibilité de mesurer la fluorescence depuis une orbite géostationnaire dans les bandes O 2 -A et O 2 -B. Les résultats de ces simulations montrent la possibilité de mesurer préférentiellement dans la bandeO 2 -A avec une faible incertitude sur les flux de fluorescence et une bonne répétabilité temporelle pour le suivi des cycles diurnes de la fluorescence de la végétationLe travail de cette thèse porte sur l’étude de la télédétection de la fluorescence chlorophyllienne avec un instrument imageur passif depuis une orbite géostationnaire pour le suivi de l’état physiologique de la végétation. Le concept instrumental est étudié théoriquement pour aboutir à la création d’uninstrument et à sa validation. La possibilité de mesurer des cycles diurnes de la fluorescence végétale depuis une orbite géostationnaire est évaluée à l’aide de simulations qui permettent de dresser les spécifications d’un instrument spatial.L’instrument imageur passif mesure dans la bande O 2 -A d’absorption atmosphérique. Il utilise une roue à filtres interférentiels dont la fonction de transmittance varie avec l’angle d’incidence des rayons les traversant. L’étude théorique a permis d’optimiser le placement spectral des filtres en vuede minimiser l’incertitude liée à la mesure de fluorescence.Grâce à la comparaison des mesures de l’instrument imageur avec d’autres instrument de mesure de la fluorescence, l’instrument et son concept instrumental ont été validés. Néanmoins, à cause d’effets de structure de la végétation intervenant sur le transfert radiatif de la fluorescence et de la lumière solaire au sein du couvert végétal, ces mesures ont confirmé la difficulté d’estimer le rendement de fluorescence de la végétation à partir des flux de fluorescence mesurés.Une étude théorique menée grâce à une modélisation du transfert radiatif de la fluorescence dans le couvert végétal jusqu’au capteur a permis d’expliquer la difficulté à retrouver le rendement de fluorescence à partir des flux. Cette étude a mis en avant l’accessibilité du rendement pour des couverts à fortedensité de feuilles et lorsque la distribution de l’orientation des feuilles est centrée sur l’horizontale.Cette modélisation a été étendue pour simuler des mesures spatiales dans le but d’étudier la possibilité de mesurer la fluorescence depuis une orbite géostationnaire dans les bandes O 2 -A et O 2 -B. Les résultats de ces simulations montrent la possibilité de mesurer préférentiellement dans la bandeO 2 -A avec une faible incertitude sur les flux de fluorescence et une bonne répétabilité temporelle pour le suivi des cycles diurnes de la fluorescence de la végétation
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Bueno, Hernandez Diana. "Optical and electrochemical sensing methods for the detection of food contaminants." Thesis, Perpignan, 2016. http://www.theses.fr/2016PERP0044/document.
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Un appareil de mesure de la fluorescence, à faible coût et portable a été développé pour quantifier les concentrations d’Ochratoxine A (OTA) dans des échantillons réels. Le système est basé sur l’excitation par une UV-LED à 365 nm et un photo détecteur contrôlé par une interface dans LabVIEW. Aussi, une image capteur, CMOS, contrôlée par une interface conçue dans MATLAB. L’OTA est une molécule naturellement fluorescente. Après excitation par une UV-, l’image de la fluorescence émise est captée par une caméra et traitée en vue de la mesure de la concentration de l’OTA. Le système d’analyse a été basé sur les 3 composants rouge, vert et bleu (RGB, selon l'acronyme anglais). La gamme est linéaire entre de 2-40 µg/L. L’extraction de l’OTA est réalisée par des colonnes d'immuno affinité (IAC, selon l'acronymeanglais) et les colonnes à empreinte moléculaire (MIP, selon l'acronyme anglais) pour les échantillons de cacao, de la bière et du vin. Les résultats obtenus ont été validés par la méthode chromatographique (HPLC). L'appareil conçu est facile à utiliser, économique et portable. En outre, l'utilisation des nouvelles technologies a été inclus tels que l'emploi du smartphone pour détecter l'OTA et la création d'un APP. Des données d'image de fluorescence provenant de la caméra du smartphone et sont analysées par un ordinateur personnel et présentés dans les composantes RGB, où l'image est envoyée à l'ordinateur par WIFI et le téléphone intelligent est utilisé comme source d'énergie trop. Enfin, une APP pour le système Android a été créé pour capturer l'image et fournit les valeurs RGB. Enfin l'utilisation du traitement de l'image a été utilisée pour quantifier l'OTA dans les échantillons réels sans colonnes IAC ou MIP, employée pour extraire la mycotoxine. L’analyse a été réalisée par des techniques colorimétriques et d’analyse de la couleurA portable and low cost fluorescence set-up to quantify the concentrations of Ochratoxin A(OTA) in real samples was developed. The detection through the device consist of anultraviolet light at 365 nm and an photo detector or a CMOS sensor controlled by anexecutable interface designed in LabVIEW or MATLAB. It has been reported that OTA is naturally fluorescent, so it allows the user to get a UV LED to excite the sample, get a value involtage when a photodetector is employed or a photograph of the OTA under excitationconditions, and process that image in order to predict the concentrations of the sample. Tocapture and process the image, in an automatically manner, the system was completely basedon the Red, Green and Blue (RGB) components. The linearity for OTA obtained in the rangeof concentrations corresponds to 2-40 µg/L. Immunoaffinity columns (IAC) and molecularimprinted polymer columns (MIP) were used with cocoa, beer and wine samples. Theobtained results were cross-validated using chromatographic method such as HPLC and theFluoroskan equipment. The developed setup is easy to use, economical and portable. Besides,the use of new tendencies was included such as employ the smartphone to detect OTA and thecreation of an APP. Fluorescence image data from the smartphone camera are analyzed by apersonal computer and presented in RGB components, where the image is sent to thecomputer by WIFI and the smartphone is used as a power source too. Finally, an APP forandroid system was created to capture the image and provides the RGB values. At the end, theuse of image processing to quantify the OTA in real samples without incorporated IAC or MIPcolumns to extract the mycotoxin from a complex solution, employing colorimetric techniquesand color analysis
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Vonnegut, Chrisgen. "Design and Application of Fluorescent Sensing Scaffolds Based upon and Originating from Conjugated Aryl-ethynyl Systems." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20413.
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The utility of fluorophores for sensing applications in the current state of the art of biological imaging hardly needs to be stated. The use of fluorophores in exploring and determining the internal structure and active dynamics of cellular processes has been pivotal, allowing us to explore areas of study inaccessible through other means. A simple search of fluorophores in Scifinder© demonstrates their popularity, as the number of hits increases year after year, until the year of 2015 when there were 1400+ journal articles published with the phrase. Fluorophore applications range far and wide, from sensing applications related to environmental concerns, to public health, to clinical usage. Fluorophores have been developed to detect explosive residues, to monitor environmental pollutants, and even to detect illicit substances.
In cellular applications, a fluorophore needs to be well suited to examining the relevant processes, including participating in the cellular milieu and actively signifying the phenomena that are desired. Chapter I examines the usage of alkynes in fluorescent sensing scaffolds and gives a survey of their applicability in the field. Chapter II demonstrates the utility of disulfide-based macrocyclic scaffolds in the design of supramolecular hosts for chloride anions and their use as solid-state sensors for these anions. Chapter III explores the synthesis and application of an alkyne-based scaffold in the reversible detection of dithiol/disulfide redox flux and a new mode of quantification of dithiol-disulfide redox couples, a classically difficult area of study. Chapter IV focuses on methods utilized to improve the disulfide-based redox sensing capabilities. Chapters V and VI explore the properties of a new fluorophore scaffold discovered during research into another sensing scaffold, demonstrating a new reaction which yields a heretofore underexplored heterocycle with novel photophysical and supramolecular behaviors.
This dissertation contains both previously published and unpublished co-authored material.
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Atherton, Jon Mark. "Multiscale remote sensing of plant physiology and carbon uptake." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6219.
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This study investigated the use of optical remote sensing for estimating leaf and canopy scale light use efficiency (LUE) and carbon exchange. In addition, a new leaf level model capable of predicting dynamic changes in apparent reflectance due to chlorophyll fluorescence was developed. A leaf level study was conducted to assess the applicability of passive remote sensing as a tool to measure the reduction, and the subsequent recovery, of photosynthetic efficiency during the weeks following transplantation. Spectral data were collected on newly planted saplings for a period of 8 weeks, as well as gas exchange measurements of LUE and PAM fluorescence measurements. A set of spectral indices, including the Photochemical Reflectance Index (PRI), were calculated from the reflectance measurements. A marked depression in photosynthetic rate occurred in the weeks after outplanting followed by a gradual increase, with recovery occurring in the later stages of the experimental period. As with photosynthetic rate, there was a marked trend in PRI values over the study period but no trend was observed in chlorophyll based indices. The study demonstrated that hyperspectral remote sensing has the potential to be a useful tool in the detection and monitoring of the dynamic effects of transplant shock. Relationships between hyperspectral reflectance indices, airborne carbon exchange measurements and satellite observations of ground cover were then explored across a heterogeneous Arctic landscape. Measurements were collected during August 2008, using the University of Edinburgh’s research aircraft, from an Arctic forest tundra zone in northern Finland as part of the Arctic Biosphere Atmosphere Coupling at Multiple Scales (ABACUS) study. Surface fluxes of CO2 were calculated using the eddy covariance method from airborne data that were collected from the same platform as hyperspectral reflectance measurements. Airborne CO2 fluxes were compared to MODIS vegetation indices. In addition, LUE was estimated from airborne flux data and compared to airborne measurements of PRI. There were no significant relationships between MODIS vegetation indices and airborne flux observations. There were weak to moderate (R2 = 0.4 in both cases) correlations between PRI and LUE and between PRI and incident radiation. A new coupled physiological radiative transfer model that predicts changes in the apparent reflectance of a leaf, due to chlorophyll fluorescence, was developed. The model relates a physically observable quantity, chlorophyll fluorescence, to the sub leaf level processes that cause the emission. An understanding of the dynamics of the processes that control fluorescence emission on multiple timescales should aid in the interpretation of this complex signal. A Markov Chain Monte Carlo (MCMC) algorithm was used to optimise biochemical model parameters by fitting model simulations of transient chlorophyll fluorescence to measured reflectance spectra. The model was then validated against an independent data set. The model was developed as a precursor to a full canopy scheme. To scale to the canopy and to use the model on trans-seasonal time scales, the effects of temperature and photoinhibition on the model biochemistry needs to be taken into account, and a full canopy radiative transfer scheme, such as FluorMOD, must be developed.
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Muñoz, Resta Ignacio. "Pyrylium salts for bioimaging, sensing and solid-state emission." Doctoral thesis, Universitat Jaume I, 2021. http://dx.doi.org/10.6035/14104.2021.782064.
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The thesis entitled "Pyrylium salts for bioimaging, sensing and solid-state emission" is structured in 7 chapters that cover different aspects related to several applications of pyrylium salts. Two chapters correspond to biological applications, in which the synthesis and characterization of molecules that are used as mitochondrial probes and nitric oxide sensors is carried out. A third one introduces an analytical application, where pyrylium compounds are used for water sensing in organic solvents. And in the last one, an optic approach is proposed and the development of a family of compounds as solid-state emitters is presented. Due to its synthetic ease and good photophysical properties, it's concluded that the use of pyrilium salts could be expanded even further in the future into fields in which they have not been fully exploited, such as bioanalysis.La tesis titulada "Pyrylium salts for bioimaging, sensing and solid-state emission" se encuentra estructurada en 7 capítulos en los que se desarrollan nuevas aplicaciones para compuestos de pirilio. Dos capítulos se corresponden con aplicaciones biológicas, en los que se lleva a cabo la síntesis y caracterización de moléculas que son utilizadas como sondas mitocondriales y sensores de óxido nítrico. Un tercero introduce una aplicación analítica, donde los pirilios se utilizan para el sensado de agua en solventes orgánicos. Y en un cuarto se plantea un enfoque desde la óptica y se presenta el desarrollo de una familia de compuestos como emisores en estado sólido. Se concluye que, debido a su facilidad sintética y sus buenas propiedades fotofísicas, el uso de sales de pirilio puede continuar expandiéndose hacia campos en los que no han sido completamente explotados, como el bioanálisis.
Programa de Doctorat en Ciències
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Finegan, Timothy Michael. "Remote three-dimensional temperature sensing using planar laser induced fluorescence : development and applications to microwave heated liquids." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/28356.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2004.Includes bibliographical references.
Microwave heating is an important technology that has been hampered in application by difficulties in measuring temperatures and temperature distributions during the microwave heating process. This thesis describes the development of a 3D imaging fluorescence thermometry system that was used to examine temporal and spatial variations in temperature within various aqueous solutions during their heating by microwave irradiation. The work provides one of the first experimentally-determined temperature maps for a system undergoing microwave heating. A 3D thermometry instrument was built based on the principles of Planar Laser Induced Fluorescence (PLIF) imaging. Temperatures were optically determined from ratiometric measurements of the fluorescence from a pair of molecular probes. A Dextran polymer labeled with Rhodamine B was used as a temperature-sensitive probe that operates between 20 and 60 ⁰C. A second temperature-insensitive probe, Rhodamine 110, was used to monitor changes in the laser emission intensity. A dual camera fluorescence detector system was employed to capture a 2D x-y plane at a specified z-axis position. A dichroic mirror and optical filters were used to separate the fluorescence signals from the two probes. The instrument was able to achieve a spatial resolution of 0.2 mm in x-y plane, a 5 mm spatial resolution in z-axis, and a temperature resolution of ±1.6 ⁰C. The 3D imaging thermometry instrument was modified for investigations into microwave heating. A microwave plasma applicator was adapted for heating experiments with water and salt solutions at concentrations ranging from 0-0.5 M.
(cont.) heating with reduced convective flows. The dynamics of microwave heating were captured in images with a 0.5 second interval. Microwave heating was observed at node positions in the microwave cavity and varied with the dielectric properties of the heated medium. The experimental results for initial heating were successfully modeled by 2D calculations of the electric field in the microwave cavity. 3D experiments were performed on both pure water sample and on a 0.1 M salt solution. Due to the rapid rate of microwave heating, the 3D experiments were conducted by repeating experiments at different positions in the microwave cavity under the same starting conditions and heating profiles. The simulations of the 2D electric fields in the microwave cavity suggest that the electric field intensity varied little across the z-axis positions. Experiments at different z-axis positions in the cavity had identical profiles within the error of the experiments.
by Timothy M. Finegan.
Ph.D.
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Huang, Liming. "Stem-loop probe for sensing unlabeled nucleic acids and design of perylene dicarboxylic imides as multi-functional materials." abstract, 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3339121.
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Bürling, Kathrin [Verfasser]. "Potential of fluorescence techniques with special reference to fluorescence lifetime determination for sensing and differentiating biotic and abiotic stresses in Triticum aestivum L. / Kathrin Bürling. Landwirtschaftliche Fakultät." Bonn : Universitäts- und Landesbibliothek Bonn, 2011. http://d-nb.info/1016599897/34.
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Finkelmeier, Nils. "Synthesis and Fluorescence Properties of Anthracene Derivatives and their Metal Complexes." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://hdl.handle.net/11858/00-1735-0000-0023-994A-7.
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Uzunova, Vanya D. [Verfasser]. "Thermodynamic and fluorescence-based investigations of Host-Dye reporter pairs for sensing of biological analytes / Vanya D. Uzunova." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1037013646/34.
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Austin, Edward Alfred Denzil. "Studies of measurement techniques for indirect chemical sensing based on fluorescence spectroscopy and applications for fibre-optic sensors." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/50196/.
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This thesis describes experimental and theoretical studies of interrogation systems for determining fluorescent decays of order a few microseconds. The studies have enabled optimised design of interrogators for sensing oxygen using a fluorescent polymerencapsulated ruthenium complex. Two basic interrogation methods were explored, using blue LED excitation. The Rapid Lifetime Detection (RLD) scheme, a fluorescence interrogation method based on direct interrogation of the decay curve following pulsed excitation was generalised, and a novel method for optimising measurement precision derived. The effect of background light on the optimum was quantified. Dissolved (aqueous) oxygen concentration was measured to a precision of 1 part per billion using a 1 second response time (the peak fluorescence power was only 12.5±0.5pW). A second interrogation method, where the phase delay between an intensity modulated excitation source and the resultant fluorescence is processed to make measurements, was for the first time, fully analysed for measurement of exponential decays. When measuring fluorescence lifetimes in the range 2.9-3.3μs, a precision of 2.3 x 10-10 s Hz-0.5 was achieved. (The peak fluorescence power was 500±25pW). A novel combination of ruby optical temperature sensor insert and oxygen sensing layer was demonstrated as a simultaneous temperature and oxygen sensor. A new fluorescence calibration standard consisting of thermally stabilised titanium-dopedsapphire sample was constructed to calibrate and test the indicators. This work was sponsored by a BRITE EuRam European project, which helped determine the priorities of the research.
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Shehata, Nader. "Design of optical characteristics of ceria nanoparticles for applications including gas sensing and up-conversion." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/49574.
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This thesis investigates the impact of doping on the optical and structural characteristics of cerium oxide (ceria) nanoparticles synthesized using chemical precipitation. The dopants selected are samarium and neodymium, which have positive association energy with oxygen vacancies in the ceria host, and negative association lanthanides, holmium and erbium, as well as two metal dopants, aluminum and iron. Characteristics measured are absorption and fluorescence spectra and the diameter and lattice parameter of ceria. Analysis of the characteristics indicates qualitatively that the dopant controls the O-vacancy concentration and the ratio of the two cerium ionization states: Ce+3 and Ce+4. A novel conclusion is proposed that the negative association lanthanide dopants can act as O-vacancies scavengers in ceria while the O-vacancy concentration increases in ceria doped with positive association lanthanide elements. Doped ceria nanoparticles are evaluated in two applications: dissolved oxygen (DO) sensing and up-conversion. In the first application, ceria doped with either Sm or Nd and ceria doped with aluminum have a strong correlation between the fluorescence quenching with the DO concentration in the aqueous solution in which the ceria nanoparticles are suspended. Stern-Volmer constants (KSV) of doped ceria are found to strongly depend upon the O-vacancy concentration and are larger than some of the fluorescent molecular probes currently used to measure DO. The KSV measured between 25-50oC is found to be significantly less temperature dependent as compared to the constants of commercially-available DO molecular probes. In the second application, up-conversion, ceria nanoparticles doped with erbium and an additional lanthanide, either Sm or Nd, are exposed to IR radiation at 780 nm. Visible emission is only observed after the nanoparticles are calcinated at high temperature, greatly diminishing the concentration of O-vacancies. It is concluded that O-vacancies do not play a dominant role in up-conversion, unlike that drawn for down-conversion, where the fluorescence intensity is strongly correlated with the O-vacancy concentration. Correlations between annealing temperatures, dopant, and dopant concentrations with the power dependence of up-conversion on the pump and the origin of the intensities of the visible emission are presented. These studies show the promise of doped ceria nanoparticles.Ph. D.
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Dong, Wenyue [Verfasser]. "The Design and Synthesis of Conjugated Polymers with Aggregation-Induced Emission and Their Application in Fluorescence Sensing / Wenyue Dong." Wuppertal : Universitätsbibliothek Wuppertal, 2015. http://d-nb.info/1076929885/34.
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Kanyuk, M., A. P. Demchenko, I. Díez, and R. H. A. Ras. "Fluorescent Few-Atom Clusters of Silver Formed in Organic Solvents on Polymeric Supports." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35122.
Full textAbstract:
Few-atom silver clusters are fluorophores with a set of attractive properties including sub-nanometer
size, high quantum yield and large Stokes shift. Sharing high photostability with semiconductor quantum
dots but being of much smaller size, lacking blinking and with expected lack of toxicity, they are especially
attractive for biological imaging, down to single molecules. No less promising are their applications in
chemical sensing and biosensing as well as for molecular optic and electronic devices on a single molecular
level. We demonstrate that it is not a unique property of water that can provide the formation and stability
of silver clusters. They can be produced on photoreduction in different organic solvents using the same polymeric
template. Unique photophysical properties of these clusters share both similarities and differences
to that of organic dyes.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35122
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Orth, Antony G. "Imaging Pressure, Cells and Light Fields." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11349.
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Imaging systems often make use of macroscopic lenses to manipulate light. Modern microfabrication techniques, however, have opened up a pathway to the development of novel arrayed imaging systems. In such systems, centimeter-scale areas can contain thousands to millions of micro-scale optical elements, presenting exciting opportunities for new imaging applications. We show two such applications in this thesis: pressure sensing in microfluidics and high throughput fluorescence microscopy for high content screening. Conversely, we show that arrayed elements are not always needed for three dimensional light field imaging.Engineering and Applied Sciences
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Leufen, Georg [Verfasser]. "Sensing the response of sugar beet and spring barley to abiotic and biotic stresses with proximal fluorescence techniques / Georg Leufen." Bonn : Universitäts- und Landesbibliothek Bonn, 2016. http://d-nb.info/1095099078/34.
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