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1
Šćepanović, Obrad R. 1980. "Light scattering spectroscopy clinical imaging device implementation". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/87887.
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2
Backman, Vadim 1973. "Early diagnosis of cancer using light scattering spectroscopy". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/29892.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 2001.Includes bibliographical references.
This thesis presents a novel optical technique, light scattering spectroscopy (LSS), developed for quantitative characterization of tissue morphology as well as in vivo detection and diagnosis of the diseases associated with alteration of normal tissue structure such as precancerous and early cancerous transformations in various epithelia. LSS employs a wavelength dependent component of light scattered by epithelial cells to obtain information about subcellular structures, such as cell nuclei. Since nuclear atypia is one of the hallmarks of precancerous and cancerous changes in most human tissues, the technique has the potential to provide a broadly applicable means of detecting epithelial precancerous lesions and noninvasive cancers in various organs, which can be optically accessed either directly or by means of optical fibers. We have developed several types of LSS instrumentation including 1) endoscopically compatible LSS-based fiber-optic system;
(cont.) 2) LSS-based imaging instrumentation, which allows mapping quantitative parameters characterizing nuclear properties over wide, several cm2, areas of epithelial lining; and 3) scattering angle sensitive LSS instrumentation (a/LSS), which enables to study the internal structure of cells and their organelles, i.e. nuclei, on a submicron scale. Multipatient clinical studies conducted to test the diagnostic potential of LSS in five organs (esophagus, colon, bladder, cervix and oral cavity) have shown the generality and efficacy of the technique and indicated that LSS may become an important tool for early cancer detection as well as better biological understanding of the disease.
by Vadim Backman.
Ph.D.
3
Thapa, Nabin K. "Characterizing Liquid-Fluid Interfaces Using Surface Light Scattering Spectroscopy". Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1564059703319064.
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4
Courtney, Peter R. "Correlation techniques for application in photon correlation spectroscopy". Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237235.
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5
Kolevzon, Vladimir. "Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface". Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-31647.
Testo completoAbstract (sommario):
Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface Vladimir Kolevzon Abstract High frequency capillary waves at liquid Ga surface have been studied by means of quasielastic light scattering spectroscopy. The observed frequencies and damping constants of waves differed greatly from classical theoretical treatment of liquid Ga surface as that of a simple liquid. This effect was explained due to the presence of the surface layer, possessing visco-elastic properties extracted, for the first time, from the fit of experimental spectra with an appropriate theoretical form. Negative value of the surface dilational viscosity has been derived for all wavenumbers studied. At high wavenumbers q the wave dispersion behavior is best likely linked to the weak coupling between dilational and capillary modes, while at low and moderate q the experimental data resemble to the mixed oscillations. This behavior is consistent with an influence of diffusion and adsorption on the waves propagation.
6
Macfadyen, Allan John. "Photon correlation spectroscopy and electrophoretic light scattering using optical fibres". Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277140.
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7
Lau, Condon. "Differential light scattering spectroscopy measurements for detecting and imaging cancer". Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35666.
Testo completoAbstract (sommario):
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references.
Optical spectroscopy show great promise for diagnosing the earliest stages of cancer. Light scattering spectroscopy (LSS), the study of single elastic backscattering as a function of wavelength and angle, can detect subcellular structural changes in early cancer. We have developed two novel differential light scattering spectroscopy techniques, space differential LSS (SD/LSS) and b-angle differential LSS (/LSS), for detecting the single backscattering signal from a reflectance spectrum dominated by multiple scattering and diffuse reflectance. SD/LSS exploits the penetration abilities of diffuse reflectance while /LSS exploits the angular asymmetry of single backscattering from large particles. O/LSS has the added advantage of being able to isolate single backscattering specifically from scatterers much larger than the wavelength. We implement /LSS to interrogate colon tissue and to develop diagnostic algorithms based on Mie theory. The results show great promise for diagnosing cancer. Instrumentation is being developed to implement SD/LSS and /LSS together in a wide area imaging system with the goal of studying and detecting cancer at its earliest stages in vivo and in real time. The system has been validated with controlled tissue phantoms and will soon be ready for clinical studies.
by Condon Lau.
S.M.
8
Kolevzon, Vladimir. "Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface". Forschungszentrum Rossendorf, 1996. https://hzdr.qucosa.de/id/qucosa%3A21991.
Testo completoAbstract (sommario):
Surface Light Scattering Spectroscopy of the Gallium Liquid-Vapor Interface Vladimir Kolevzon Abstract High frequency capillary waves at liquid Ga surface have been studied by means of quasielastic light scattering spectroscopy. The observed frequencies and damping constants of waves differed greatly from classical theoretical treatment of liquid Ga surface as that of a simple liquid. This effect was explained due to the presence of the surface layer, possessing visco-elastic properties extracted, for the first time, from the fit of experimental spectra with an appropriate theoretical form. Negative value of the surface dilational viscosity has been derived for all wavenumbers studied. At high wavenumbers q the wave dispersion behavior is best likely linked to the weak coupling between dilational and capillary modes, while at low and moderate q the experimental data resemble to the mixed oscillations. This behavior is consistent with an influence of diffusion and adsorption on the waves propagation.
9
Dahlgren, Eric D. "Small angle light scattering analysis of tissue". Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0111102-171921.
Testo completo
10
Jefferies, J. P. F. "Multipassed Fabry-Perot spectroscopy and its Fourier analysis". Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375074.
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11
Campbell, Dawn M. "Light scattering study of attractive interactions in a model microemulsion system /". Online version of thesis, 1992. http://hdl.handle.net/1850/10697.
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12
Bassan, Paul. "Light scattering during infrared spectroscopic measurements of biomedical samples". Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/light-scattering-during-infrared-spectroscopic-measurements-of-biomedical-samples(a2a41f54-0e61-443a-bd32-faf8f65806a7).html.
Testo completoAbstract (sommario):
Infrared (IR) spectroscopy has shown potential to quickly and non-destructively measure the chemical signatures of biomedical samples such as single biological cells, and tissue from biopsy. The size of a single cell (diameter ~10-50 µm) are of a similar magnitude to the mid-IR wavelengths of light (~1-10 µm) giving rise to Mie-type scattering. The result of this scattering is that chemical information is significantly distorted in the IR spectrum.Distortions in biomedical IR spectra are often observed as a broad oscillating baseline on which the absorbance spectrum is superimposed. A spectral feature commonly observed is the sharp decrease in intensity at approximately 1700 cm-1, next to the Amide I band (~1655 cm-1), which pre-2009 was called the 'dispersion artefact'. The first contributing factor towards the 'dispersion artefact' investigated was the reflection signal arising from the air to sample interface entering the collection optics during transflection experiments. This was theoretically modelled, and then experimentally verified. It was shown that IR mapping could be done using reflection mode, yielding information from the optically dense nucleus which previously caused extinction of light in transmission mode.The most important contribution to the spectral distortions was due to resonant Mie scattering (RMieS) which occurs when the scattering particle is strongly absorbing such as biomedical samples. RMieS was shown to explain both the baselines in IR spectra, and the 'dispersion artefact' and was validated using a model system of poly(methyl methacrylate) (PMMA) of varying sizes from 5 to 15 µm. Theoretical simulations and experimental data had an excellent match thus proving the theory proposed. With an understanding of the physics/mathematics of the spectral distortions, a correction algorithm was written, the RMieS extended multiplicative signal correction (RMieS-EMSC). This algorithm modelled the measured spectrum as superposition of a first guess (the reference spectrum) which was of a similar biochemical composition to the pure absorbance spectrum of the sample, and a scattering curve. The scattering curve was estimated as the linear combination of a database of a large number of scattering curves covering a range of feasible physical parameters. Simulated and measured data verified that the RMieS-EMSC increased IR spectral quality.
13
Paladugula, Jithendar. "Parallelization of light scattering spectroscopy and its integration with computational grid environments". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0005280.
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14
Zhang, Fan. "Theoretical examinations of optical tomography through scattering medium". Thesis, University of Nottingham, 2015. http://eprints.nottingham.ac.uk/28681/.
Testo completoAbstract (sommario):
Optical tomography is considered to be a non-invasive and non-ionising technique that can create a digital volumetric model of an object by reconstructing 3D images made from light transmitted and scattered through the object. It is becoming of increasing importance in the area of tissue engineering and biomedical diagnostics. The main limit of pure optical techniques is the heavy scattering of tissue, which causes a poor imaging resolution. Ultrasound modulated optical tomography (USMOT) combines optical and ultrasonic techniques to produce optical contrast at ultrasound resolution. The modulation mechanism for incoherent USMOT is considered to be a secondary effect when coherent light is used. However, it is still valuable as it offers a chance to simulate the modulation of fluorescent light. In this thesis, several models of fluorescence imaging systems are presented including incoherent USMOT, Fluorescence lifetime extraction system, full field illumination (FI) system and scanning input (SI) system. A simple incoherent USMOT model is presented which allows varying of acoustic and optical parameters to provide an optimum setup to measure the incoherent USMOT effect. Afterwards, the combination of incoherent USMOT and fluorescence imaging is applied to provide an optimized SNR of modulated fluorescent light by changing the modulation frequency. With the presence of ultrasound, a novel lifetime extraction technique is presented which provides more accurate lifetime measurements and further makes it possible to extract fluorescence lifetimes in a heavily scattering medium. A broad range of excitation and emission optical parameters of NIR fluorescence imaging system have been investigated which aims to find out the optimized imaging pairs based on the SNR and spatial resolution detected. The scanning input system turns out to be better than the full field illumination system based on the spatial resolution detected, and longer wavelengths may lead to a higher SNR but degraded spatial resolution. The spatial resolution has been taken into account in fluorophore and imaging system selection over a broad range of excitation and emission wavelength. Experimental results are shown as well as a supplement to the simulations.
15
Bassi, Andrea Li. "X-ray and light scattering from nanostructured thin films". Thesis, Durham University, 2000. http://etheses.dur.ac.uk/4631/.
Testo completoAbstract (sommario):
The object of this thesis is the study of nanostructured thin films using inelastic fight scattering and elastic x-ray scattering techniques. Their use in combination with other techniques is a powerful tool for the investigation of nanostructured materials. X-ray, Raman and Brillouin characterisation of cluster-assembled carbon films, promising for applications in the field of catalysis, hydrogen storage and field emission, is here presented. X-ray reflectivity (XRR) provided a measure of the density. Raman spectroscopy showed that the local bonding in these amorphous films depends on the size distribution of the clusters and that it is possible to select the cluster size in order to grow films with tailored properties. Brillouin scattering provided a characterisation at the mesoscopic scale and an estimate of the elastic constants, revealing a very soft material. XRR was employed to study density, layering and roughness of a wide range of amorphous carbon films grown with different techniques. Some films possess an internal layering due to plasma instabilities in the deposition apparatus. By comparing XRR with Electron Energy Loss Spectroscopy, a unique value for the electron "effective mass" was deduced and a general relationship between sp(^3)-content and density was found. XRR and H effusion were used to determine the hydrogen content. A study of the size-dependent melting temperature in tin nanoparticle thin films was undertaken with a combined use of X-Ray Diffraction (XRD) and light scattering. A redshift in the position of a Rayleigh peak in the temperature-dependent Brillouin measurements was shown to be related to the melting of the nanoparticles and explained by an effective medium model. XRD also provided information on the low-level of stress in the particles. Low-frequency Raman scattering was used to study the behaviour of the acoustic modes of a single particle as a function of temperature.
16
Dorrington, Glen. "Examining biological systems at a molecular level via polarised light spectroscopy and scattering turbidity". Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/106536/.
Testo completoAbstract (sommario):
During the course of this work the development and optimisation of the dichroism field of spectroscopic techniques regarding their application towards living biological systems has been examined. To this end we have studied the theory of light scattering, as one of the principle flaws that can prevent accurate analysis of spectral data. The fields of Rayleigh-Gans-Debye and Mie theory were investigated and implemented into a program for the calculation of scattering for various different systems. The developed program was then optimised using previously collected data regarding the scattering produced by liposomes under flow, and further data regarding the deformation of liposomes validated. A secondary feature to be addressed was the inherent complexity of cellular spectra that comprise a variety of different components. Experimental studies were therefore conducted regarding the deconvolution of several biological systems in terms of their individual chromophores, in increasing degrees of complexity. An approach in which each component was converted into a series of Gaussian curves and the contribution of sets of these Gaussians (from each component) to the overall system spectrum was developed. Since biological systems contain various components that interact with each other, such as the hypochromicity of DNA, the influence on this spectral decomposition approach was also outlined and studied. Unusual features were observed in the most complex cellular samples of red blood cells and fission yeast, regarding the linear dichroism (LD) spectra produced in the absence of flow. Further studies were conducted regarding the simpler of these systems, red blood cells, to determine the source of these spectral features. The principle component was determined to be oxy-hemoglobin, and that both cellular and protein orientation was required to produce the observed LD spectrum. Sedimentary forces were then discovered to be the signal source within the sample vessel, and the spectrum comprised of both absorbing and scattering elements. Of the latter, both typical RGD/Mie type scattering was observed in addition to resonance scattering. In addition, it was observed that alterations to the cellular geometry, due to various environmental influences such as pH and tonicity, were directly related to spectral behaviour.
17
Peetermans, Joyce Anne. "Brownian motion of macromolecules inside single intact biological cells : microscope laser light scattering spectroscopy". Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15178.
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18
Carlsson, Sofia. "Surface Characterization ofGram-Negative Bacteria andtheir Vesicles : Using Fourier Transform Infrared Spectroscopy andDynamic Light Scattering". Thesis, Umeå universitet, Kemiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-64292.
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19
Addis, Matthew James. "Transitional metal trilayers and films investigated using Brillouin light scattering and the magneto-optic Kerr effect". Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243210.
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20
Lewis, Kristin A. "Development of a dual-wavelength photoacoustic instrument for measurement of light absorption and scattering by aerosol and gases". abstract and full text PDF (free order & download UNR users only), 2007. 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:3258842.
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21
Kalashnikov, Maxim M. "Validation of angle-resolved polarized light scattering spectroscopy as a diagnostic tool for pre-cancer detection". Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49744.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2009.Vita.
Includes bibliographical references.
Light scattering spectroscopy has emerged as a valuable diagnostic tool for cancer diagnoses in the past ten years. The interaction of light with cellular structures brings out information about morphological changes accompanying malignancy at early stages. The virtue of this technique is to extract key morphological information such as size distribution of nucleus and submicron-sized particles with minimal data acquisition and model-based data analysis. This enables wide area screening and onsite analysis, critical to the clinical applications. The extracted information, however, strongly depends on the selection of the specific model of the cell/tissue scattering and on constraints from prior knowledge about the sample, leaving the validity of the information questionable. The main focus of this thesis work is to validate various models of cell/tissue scattering used in light scattering spectroscopy. Conventional intensity-based light scattering spectroscopy, which records intensity distribution at the angular plane, was set up to measure angular and wavelength distribution of scattered light in cell monolayers, cell suspensions and rat esophagus tissues for both forward and backward scattering. Morphological information was extracted from cell models such as the cell model based on Mie theory and the power-law model. At the same time, field-based microscopy was used to measure 3D refractive index distributions of single live cells and to provide intensity-based light scattering spectroscopy with a more realistic optical model of a cell.
(cont.) From the index tomogram, the contribution of individual organelles and cellular components to the light scattering was determined without the need for modeling. Indeed, field-based microscopy was used as a validation tool for the various models and assumptions used in the intensity-based approach. Two types of scattering behavior had been previously reported for a visible range of wavelengths and an angular range of forward-to-backscattering in cells and tissues: an oscillatory behavior of scattering intensity in angle near exact forward and exact backward scatterings associated with cell body or nuclei, and smooth power-like behavior in wavelength for all scattering angles except near forward scattering. This study addresses two key questions related to the two types of behavior mentioned above: feasibility of extracting nuclear size distribution from oscillatory behavior, and extracting cellular parameter(s) characterizing smooth power law decay. To answer the first question, we performed a light scattering study with a single cell using field-based microscopy. Relative contributions to forward scattering of the cell border, the nucleus and other sub-cellular structures were established for the HT29 cell. Nuclear scattering is found to be small compared to the cell border scattering and sensitive to scattering by other sub-cellular structures. In agreement with single cell results, the cell border signal dominates forward scattering in cell suspensions of HeLa cells. This was confirmed by modeling with Mie theory and by index-matching the cell-media interface.
(cont.) Cell border signal was not observed in backscattering from cell suspensions, even with the use of large particle signal enhancement methods. Thus, the nuclear signal is estimated to be a few orders of magnitude below the current system sensitivity level and mixed with other scatterers' signals. The main scattering feature is a smooth power law in scattering wavelength. The exponent characterizing smooth power law decay, can separate normal and pre-cancerous tissues within the same tissue type, such as rat esophagus tissue. The range of power law exponents observed in the rat tissue experiments overlaps with the range of power law exponents extracted from HeLa, HT29 and T84 monolayers. Therefore, the power law exponent does not have enough dynamic range to separate independent samples with quite different morphology. In conjunction with the last statement, the power law behavior is explained by three different morphological base sets: the Mie model, describing cell as a collection of spheres, the Fourier model, in which cell is described as combination of periodic structures with a continuous range of spatial frequencies, and a fractal model, in which index fluctuations inside the cell are described by von Karman correlation function. Although all three models can explain the power law behavior, the Fourier model is the most feasible one, because, unlike the other models, no assumptions are made about structure of the sample.
by Maxim M. Kalashnikov.
Ph.D.
22
Tarcea, Nicolae [Verfasser], e Jürgen [Akademischer Betreuer] Popp. "Light as a universal tool : Microcapsule sizing by elastic light scattering and mineral investigation by in situ Raman spectroscopy / Nicolae Tarcea. Betreuer: Jürgen Popp". Würzburg : Universität Würzburg, 2004. http://d-nb.info/1099791316/34.
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23
Castorano, Nicholas Joseph. "The Structure and Dynamics of Diacetylene-Lipid Langmuir Monolayers". Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1279558411.
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24
Plaster, Bradley R. (Bradley Robert) 1976. "Dynamic light scattering and diffusing wave spectroscopy studies of the microscopic dynamics of polystyrene latex spheres suspened in glycerol". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/36673.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 1999.Includes bibliographical references (leaf 50).
The dynamics of polystyrene latex spheres [650 A radius] suspended in glycerol have been studied using the techniques of dynamic light scattering in the single scattering limit and diffusing wave spectroscopy in the multiple scattering regime using a charge coupled device [CCD] camera as our detector. Our experiments, which investigated suspensions of various concentrations [0.001by Bradley R. Plaster.
S.B.
25
Flückiger, Leonie [Verfasser], Thomas [Akademischer Betreuer] Möller e Tim [Akademischer Betreuer] Laarmann. "Dynamics of single clusters in intense light pulses studied with ion spectroscopy and light scattering / Leonie Flückiger. Betreuer: Thomas Möller. Gutachter: Thomas Möller ; Tim Laarmann". Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1077818696/34.
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Cheng, Juan. "Light scattering study on phase transition and micro-heterogeneity in relaxor ferroelectrics (1-x)Pb(Mg₁/₃Nb₂/₃)O₃-xPbTiO₃ and (1-x)Pb(Zn₁/₃Nb2₂/₃)O₃-xPbTiO₃ /". access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?phd-ap-b23749179f.pdf.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--City University of Hong Kong, 2009."Submitted to Department of Physics and Material Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 140-167)
27
Hartschuh, Ryan D. "Optical Spectroscopy of Nanostructured Materials". University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1195016254.
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Kätzel, Uwe. "Dynamic Light Scattering for the Characterization of Polydisperse Fractal Systems by the Example of Pyrogenic Silica". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1197634640783-66357.
Testo completoAbstract (sommario):
Dynamic light scattering (DLS) is a method to size submicron particles by measuring their thermal motion (diffusion) in suspensions and emulsions. However, the validity of the Stokes-Einstein equation that relates the diffusion coefficient and the particle size is limited to spherical particles and very low concentrations. Within this thesis, DLS is used for the characterization of suspensions of pyrogenic silica which consists of fractal-like aggregates composed of sintered spherical primary particles. These structural features clearly complicate the understanding of DLS experiments and have been a severe obstacle to employing DLS as routine standard tool for the characterization of pyrogenic silica. The main objective of this thesis is therefore to evaluate the application of DLS in product development and quality assurance of pyrogenic silica industry, what essentially means to identify those structural properties of fractal aggregates which are measurable with DLS and to quantify the method’s sensitivity to changes in these properties. The investigations presented here are split up into four parts, simulations that establish a relation between structural and hydrodynamic properties, experiments validating the simulation results, the characterization of concentrated suspensions and the application-oriented analysis of DLS data for specific industrially relevant measurement tasksDie Dynamische Lichtstreuung (DLS) ist eine Messmethode zur Größenbestimmung submikroner Partikel. Dabei wird primär die stochastische Bewegung der Teilchen (Diffusion) in Suspensionen und Emulsionen bewertet. Die Stokes-Einstein Gleichung, die das Verhältnis zwischen gemessenem Diffusionskoeffizienten und Partikelgröße wiedergibt, ist jedoch nur für kugelförmige Teilchen, die in sehr niedriger Konzentration vorliegen, gültig. In der vorliegenden Arbeit wird die dynamische Lichtstreuung zur Charakterisierung von Suspensionen pyrogener Kieselsäure eingesetzt. Diese besteht aus fraktalen Aggregaten, die wiederum aus versinterten aber meist kugelförmigen Primärpartikeln zusammengesetzt sind. Diese strukturellen Eigenschaften erschweren die Anwendbarkeit der DLS bzw. die Interpretation der Messergebnisse und verhinderten bisher den Einsatz der DLS als Routinemethode zur Charakterisierung pyrogener Kieselsäuren. Das Hauptziel dieser Arbeit ist daher eine Bewertung der Möglichkeiten der DLS für die Produktentwicklung und Qualitätssicherung in der Herstellung pyrogener Kieselsäuren. Das bedeutet im Besonderen, dass sowohl die messbaren granulometrischen Eigenschaften als auch die Sensitivität der Methode bei Eigenschaftsänderungen ermittelt werden müssen. Die hier durchgeführten Arbeiten sind in vier Teile gegliedert: Simulationen, die eine Beziehung zwischen strukturellen und hydrodynamischen Eigenschaften herstellen, Experimente zur Validierung der Simulationsergebnisse, die Charakterisierung konzentrierter Suspensionen und die anwendungsorientierte Auswertung von DLS-Daten für spezifische industrierelevante Messaufgaben
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Townsend, Peter Stephen Morris. "Diffusion of light adsorbates on transition metal surfaces". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274001.
Testo completoAbstract (sommario):
Helium-3 surface spin echo spectroscopy (HeSE) has been used to measure the diffusive dynamics of adsorbates on close-packed metal surfaces, namely hydrogen on Cu(111), Pd(111) and Ru(0001), carbon and oxygen on Ru(0001), and oxygen on Cu(111). Chapter 2 reviews the HeSE technique and describes the relevant dynamical models and statistical methods used to interpret data in later chapters. The performance of the ionizing detector is analysed, with a focus on the signal-to-noise ratio. In Chapter 3 expressions for the classical intermediate scattering function (ISF) are introduced for open and closed systems. The effects of corrugation and surface-perpendicular motion on the amplitude of different components in the ISF are modelled analytically and compared with simulation. The exact ISF for a particle on a flat surface, obeying the Generalized Langevin Equation with exponential memory friction, is calculated analytically. In Chapter 4 the analytical ISF is calculated for quantum Brownian motion and for coherent tunneling dynamics in a tight binding system. The bounce method for calculating quantum mechanical hopping rates in dissipative systems is applied to model diffusion of hydrogen on Ru(0001). Chapter 5 presents the first HeSE measurements of carbon and oxygen diffusion. C/Ru(0001) diffusion is assigned to a small carbon cluster. The jump rate has an activation energy $E_{A}=292\pm7\,$meV in the temperature range $550\,\textrm{K}\leq T \leq 1300\,$K. Oxygen diffusion is significantly slower. By comparison of literature data with the new HeSE results, the activation energy for oxygen diffusion at low coverage is estimated as $650\pm10$meV. Oxygen measurements at high coverage $\theta\approx0.22\,$ML are consistent with strong mutual O-O interactions. Surface diffusion is also observed after exposing Cu(111) to oxygen. Chapter 6 presents low-coverage measurements of protium (H) and deuterium (D) diffusion on Ru(0001), Pd(111) and Cu(111). In the quantum activated regime there is evidence for multiple jumps in all three systems, suggesting a low dynamical friction. The measurements on Ru(0001) indicate that the deep tunneling rate is much slower for D than for H.
30
Nonoyama, Akihisa. "Using Multiwavelength UV-Visible Spectroscopy for the Characterization of Red Blood Cells: An Investigation of Hypochromism". [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000508.
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Pilgrová, Tereza. "Vliv podmínek přípravy na solubilizační vlastnosti a stabilitu komplexů biopolymer-tenzid". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216814.
Testo completoAbstract (sommario):
Influence of the preparing of a biopolymer-surfactant system on its solubilization properties and stability was investigated by using fluorescence spectroscopy and dynamic light scattering methods. Investigation was made on complex of native hyaluronan with cationic surfactant cetyltrimethylammonium bromide (CTAB). System has been studied in aqueous and in saline solutions. The effect of temperature of stock solutions and freezing effect on subsequent properties were investigated. Further was examinated, what effect has a way of introducing fluorescent probe into the system on subsequent solubilization properties. It was found that the conditions of preparing of biopolymer-surfactant system have a significant effect on the solubilization properies and stability of complex.
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Bouloussa-Huynh, Hedi. "Spectroscopie Brillouin dans les couches minces, multicouches et nanostructures magnétiques : étude de l’interaction Dzyaloshinskii-Moriya". Thesis, Paris 13, 2019. http://www.theses.fr/2019PA131025.
Testo completoAbstract (sommario):
Ce travail vise à étudier, expérimentalement et théoriquement, le comportement des ondes de spin dans des couches ultraminces, multicouches et nanostructures magnétiques en présence de l’interaction Dzyaloshinskii-Moriya d’interface (DMI). A cet effet, nous avons utilisé la spectroscopie Brillouin (BLS) de diffusion inélastique de la lumière comme sonde expérimentale. Cette technique s’est avérée un outil extrêmement efficace pour mesurer la DMI ; effet qui se traduit par une asymétrie des raies Stokes et anti-Stokes d’un spectre BLS d’un système magnétique mince en contact d’un métal lourd produisant un fort couplage spin-orbite (SOC, acronyme anglais). Ainsi,en présence de DMI, les fréquences de deux ondes de spin se propageant dans des directions opposées seront différentes du fait de la brisure de symétrie par inversion.Différents systèmes ont été abordés et différentes situations et paramètres ont été considérés.Sur les systèmes simples en couches ultraminces, le comportement en fonction de l’épaisseur du film magnétique ou encore l’effet du recuit ont été cernés mettant en évidence le caractère interfacial de la DMI et le rôle de la qualité structurale et chimique de l’interface ferromagnétique/métal lourd. Par ailleurs, nous avons montré que l’addition d’impuretés non magnétiques à fort SOC dans des métaux légers interfacés avec un ferromagnétique peut constituer une approche efficace pour améliorer et contrôler simultanément l’amortissement magnétique, l’anisotropie perpendiculaire ainsi que la DMI. Une corrélation entre ces paramètres issus du SOC a été démontrée.Dans les empilements de couches minces, une attention particulière a été dévolue au rôle des couplages d’échange, dipolaire et des anisotropies magnétiques sur le comportement des ondes de spin en présence de DMI. Il apparaît que la mesure quantitative de la DMI peut s’écarter nettement de celle obtenue à partir de l’expression analytique éprouvée pour les couches minces simples où la valeur de la DMI est directement proportionnelle au vecteur d’onde des ondes de spin. Un calcul complet est ainsi nécessaire pour tous les cas non-symétriques (interfaces non équivalentes, anisotropies d’interface différentes,. . . ). Les résultats théoriques présentés à cet effet représentent un outil extrêmement utile.L’étude de différents réseaux de nanolignes présentant une DMI a été l’occasion de mettre en évidence les effets de taille et de périodicité dans différentes situations. Des nanolignes complètement découplées ou en contact physique partiel sur l’épaisseur ont été abordées. Nous avons ainsi mis en évidence l’absence de DMI pour des ondes de spin stationnaires selon la largeur des lignes découplées et corrélé le comportement des ondes de spin à leur longueur d’atténuation et la périodicité des réseaux, alors qu’un comportement magnonique modulé par la présence de la DMI a été observé pour les lignes couplées par l’intermédiaire d’un film ferromagnétique. Les résultats obtenus dans ce travail de thèse participent à la compréhension du comportement magnétique dynamique de systèmes en présence de DMI pouvant contribuer à l’ingénierie efficace de systèmes pour l’électronique de spin du futur ou la spin-orbitronique,notamment à base de configurations de spin chirales tels que les skyrmionsThis work aims to investigate, experimentally and theoretically, the behavior of spin waves (SW) in ultrathin layers, multilayers and magnetic nanostructures in the presence of interface Dzyaloshinskii-Moriya interaction (DMI). For this purpose, we used the Brillouin light scattering spectroscopy (BLS) as an experimental probe. This technique has proven to be an efficient tool for measuring the DMI; an effect that results in an asymmetry of the Stokes and anti-Stokes lines of a BLS spectrum for a thin ferromagnetic film in contact with a heavy metal producing a strong spin-orbit coupling (SOC). Thus, in the presence of DMI, the frequencies of two SW propagating in opposite directions will be different due to inversion symmetry breaking.Different systems were discussed and different situations and parameters were considered.On simple ultrathin layer systems, the behavior as a function of the thickness of themagnetic film or the effect of annealing have been identified, highlighting the interfacial nature of the DMI and the role of the structural and chemical quality of the ferromagnetic/heavy metal interface.Moreover, we have shown that the addition of non-magnetic impurities with high SOC in light metals interfaced with a ferromagnetic layer can be an effective approach to simultaneously improveand control magnetic damping, perpendicular anisotropy and DMI. A correlation between these SOC parameters has been also demonstrated. In thin film stacks, particular attention has been dedicated to the role of dipolar coupling,exchange coupling and magnetic anisotropy on the behavior of SW in the presence of DMI. It appears that the quantitative measurement of the DMI can deviate significantly from that obtained from the analytical expression known for simple thin layers where the value of the DMI is directly proportional to the wave vector of the SW. A complete calculation is thus necessary for all non-symmetrical cases (non-equivalent interfaces, different interface anisotropies, etc. . . ).The theoretical results presented for this purpose represent an extremely useful tool.The study of different nanostripes arrays in presence of DMI was the opportunity to highlight the effects of size and periodicity in different situations. Completely decoupled nanostripes or inpartial physical contact with periodic layer thickness were discussed. We have thus demonstrated the absence of DMI for stationary spin waves according to the width of the decoupled stripes and correlated the behavior of the SW with their attenuation length and the periodicity of the arrays, whereas a modulated magnetic behavior by the presence of the DMI was observed for the coupled stripes via a ferromagnetic film.The results obtained in this thesis work contribute to the understanding of the dynamic magnetic behavior of systems in the presence of DMI that can contribute to the efficient engineering of future systems for spintronics or spin-orbitronics, particularly based on configurations of chiral spin texture such as skyrmions
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Pardaev, Shokir A. "LIGHT SCATTERING STUDIES OF DEFECTS IN NEMATIC/TWIST-BEND LIQUID CRYSTALS AND LAYER FLUCTUATIONS IN FREE-STANDING SMECTIC MEMBRANES". Kent State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=kent1497022792130101.
Testo completo
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Nilsson, Annica M. "Daylighting Systems : Development of Techniques for Optical Characterization and Performance Evaluation". Doctoral thesis, Uppsala universitet, Fasta tillståndets fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-183307.
Testo completoAbstract (sommario):
Successful integration of daylighting systems requires the ability to predict their performance for given climates. In this dissertation, a bottom-up approach is applied to evaluate the optical performance of a selection of daylighting systems. The evaluations are based on the optical properties of the included materials, and part of the dissertation focuses on developing new optical characterization methods. The work on characterization techniques uses an integrating sphere method to characterize the transmittance of light scattering samples more accurately. The method's principle is to reduce the discrepancy in light distribution between the reference and the sample scans by using an entry port beam diffuser. For samples exhibiting distinct light scattering patterns, the benefits of improved uniformity outweigh the errors introduced by the diffusing material. The method is applicable to any integrating sphere instrument, and its simplicity makes it suitable for standard measurements. In addition to normal-hemispherical properties, many daylighting applications require knowledge of the system's spatial light distribution. This dissertation presents a method combining experimental techniques and ray tracing simulations to assess the light distribution from a Venetian blind system. The method indicates that ray tracing based on simplified optical data is inadequate to predict the light distribution for slat materials exhibiting both specular and diffuse properties. Ray tracing is a promising complement to experimental methods used to characterize light guiding or light redirecting systems. Here, spectrophotometric measurements of a scaled mirror light pipe validate a ray tracing model. The model shows excellent agreement with experimental results for both direct and diffuse incident light. The spectral evaluation shows no dramatic color changes for the transmitted light. The ray tracing model is used to evaluate four daylighting systems for a selection of Swedish locations. The percentage of occupied time when the studied systems achieve full design illuminance is relatively low, but the systems provide a valuable contribution to the required illuminance. Additionally, this dissertation provides an overview of available energy efficient windows and illustrates the importance of including the solar energy transmittance when evaluating window energy performance. Overall, this dissertation presents optical characterization techniques for improved performance evaluations of daylighting systems.
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Gobrecht, Alexia. "Vers une nouvelle approche optique pour la caractérisation des sols par spectrométrie visible et proche infrarouge". Thesis, Montpellier, SupAgro, 2014. http://www.theses.fr/2014NSAM0038/document.
Testo completoAbstract (sommario):
Avec l'objectif de réduire de la quantité de gaz à effets de serre dans l'atmosphère, les pouvoirs publics encouragent les pratiques ayant vocation à séquestrer du carbone dans les sols (reforestation, changement de pratiques agricoles). Pour en évaluer les réels bénéfices, des outils analytiques rapides, précis et peu coûteux sont nécessaires pour pouvoir comptabiliser précisément les stocks de carbone et leur évolution dans le temps. La Spectroscopie proche infrarouge (SPIR) est une technologie analytique adaptée à ce cahier des charges mais relève encore du domaine de la recherche en science du sol.Cette thèse s'est focalisée sur la première étape de cette méthode analytique: la formation du signal. Les sols étant des milieux très complexes, en termes de composition chimique et de structure physique, le signal spectroscopique est négativement impacté par les phénomènes de diffusion. Les conditions de la loi de Beer-Lambert n'étant plus remplies, les modèles chimiométriques pour prédire la teneur en carbone des sols sont moins précis et robustes. Nous proposons un système optique de mesure spectrale original et adapté aux milieux très diffusants, qui se base sur le principe de polarisation de la lumière. Il permet de sélectionner les photons ayant été moins impactés par le phénomène de diffusion. Ce signal est utilisé pour calculer un signal d'absorbance étant une bonne approximation de l'absorbance de Beer-Lambert.Ce dispositif, appelé PoLiS, a été validée expérimentalement sur des milieux modèles liquides et particulaires. Appliquée des sols pour prédire la teneur en carbone organique, les modèles de prédictions sont meilleurs avec l'absorbance calculée par PoLiS qu'avec l'absorbance calculée classiquement à partir de la mesure de réflectanceWith the goal of reducing the amount of greenhouse gases in the atmosphere, policy makers encourage practices intended to sequester carbon in soils (reforestation, changes in farming practices). New methods are required to rapidly and accurately measure soil C at field- and landscape-scales. Near infrared spectroscopy (NIRS) is an analytical technology adapted to these specifications but remains experimental research in soil science.This thesis has focused on the first step of this analytical method: signal formation. The soils are very complex materials, in terms of chemical composition and physical structure. Hence, the spectroscopic signal is negatively impacted by light scattering. Consequently, the conditions of the Beer-Lambert are no longer fulfilled, and the chemometric models to predict the carbon content of soils are less accurate and robust. We develop an original optical method based on light polarization spectroscopy to measure the absorbance of highly scattering materials. By selecting photons being less scattered, we compute a new absorbance signal which is a good approximation of the Beer-Lambert absorbance.This method, called Polis, was experimentally validated on model materials in liquid and powdered form. Applied on soils to predict Total Organic Content, the model built with the PoLiS absorbance outperform the models built with the classical absorbance computed from the diffuse reflectance signal
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Sharifian, Gh Mohammad. "Adsorption and Transport of Drug-Like Molecules at the Membrane of Living Cells Studied by Time-Resolved Second-Harmonic Light Scattering". Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/524558.
Testo completoAbstract (sommario):
ChemistryPh.D.
Understanding molecular interactions at the surfaces of cellular membranes, including adsorption and transport, is of fundamental importance in both biological and pharmaceutical studies. At present, particularly with respect to small and medium size (drug-like) molecules, it is desirable to gain an understanding of the mechanisms that govern membrane adsorption and transport. To characterize drug-membrane interactions and mechanisms governing the process of molecular uptake at cellular membranes in living organisms, we need to develop effective experimental techniques to reach quantitative and time-resolved analysis of molecules at the membrane surfaces. Also, we preferably want to develop label-free optical techniques suited for single-cell and live cell analysis. Here, I discuss the nonlinear optical technique, second-harmonic light scattering (SHS), for studying molecule-membrane interactions and transport of molecules at the membrane of living cells with real-time resolution and membrane surface-specificity. Time-resolved SHS can quantify adsorption and transport of molecules, with specific nonlinear optical properties, at living organisms without imposing any mechanical stress onto the membrane. This label-free and surface-sensitive technique can even differentiate molecular transport at individual membranes within a multi-membrane cell (e.g., bacteria). In this dissertation, I present our current research and accomplishments in extending the capabilities of the SHS technique to study molecular uptake kinetics at the membranes of living cells, to monitor bacteria membrane integrity, to characterize the antibacterial mechanism-of-action of antibiotic compounds, to update the molecular mechanism of the Gram-stain protocol, to pixel-wise mapping of the membrane viscosity of the living cells, and to probe drug-induced activation of bacterial mechanosensitive channels in vitro.
Temple University--Theses
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Dunkhorst, Kirsten. "Diffusionsmessungen an Polyethylenglykolen mittels PFG-NMR-Spektroskopie und dynamischer Lichtstreuung / Diffusion measurements of poly(etylene glycol) in solution by Pulsed Field Gradient NMR spectroscopy and Dynamic Light Scattering". Gerhard-Mercator-Universitaet Duisburg, 2005. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-05052005-170324/.
Testo completoAbstract (sommario):
The Pulsed Field Gradient (PFG) NMR spectroscopy was uesd to determine, via the diffusion coefficient, the molecular weights and the molecular weight distributions for sampels of poly(etylene glycol) (PEG) in D2O. Additional it was investigated, whether the components of mixtures of poly(ethylene glycol) with different molecular weights could be quantitatively determined by the differences in diffusion coefficient. The results of this study are compared with the result of the Dynamic Light Scattering (DLS) technique, the standard methode for the determination of molecular weights. The PFG NMR findings shows that the the molecular weights and the molecular weight distributions agreed well with values provided by the manufacturer. The mixtures could not be determined quantitativley, because of considerable overlaps in the molecular weight distributions. But it could be shown that the PFG NMR spectroscopy and the DLS technique complement one another.
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Moro, Carlo Frederico. "Comportamento do peptídeo entomotóxico jaburetox-2Ec em solução e a sua interação com lipossomas miméticos de plaquetas humanas". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/28438.
Testo completoAbstract (sommario):
No presente trabalho, o peptídeo inseticida recombinante Jaburetox-2Ec, derivado da urease de Canavalia ensiformis (Jack bean) foi estudado, principalmente através de técnicas de espectroscopia de espalhamento de luz e raios-X. Foi analisada a tendência do peptídeo a se agregar em diferentes condições físico-químicas quando em solução aquosa, e a sua interação com membranas de lipossomas miméticos de plaquetas humanas. A partir dos dados de raio hidrodinâmico, raio de giro, e massa molar ponderal média obtidos do peptídeo em solução, foi possível observar uma tendência para maior agregação numa faixa em torno de pH 5,5, bem como ausência de agregação em pH inferior a 4,0 e superior a 7,0. Não se verificou nenhum efeito visível no nível de agregação com a adição de agente redutor ou íons, sendo que a exposição ao oxigênio do ar levou a um aumento da mesma. Os estudos de interação do Jaburetox-2Ec com lipossomas revelaram uma significante mudança estrutural na membrana, que se mostrou mais intensa com uma maior concentração do peptídeo. Foram, através de software, feitos ajustes teóricos das curvas de espalhamento de raios-X à baixos ângulos dos lipossomas, a fim de quantificar as mudanças nos parâmetros físicos das membranas causados pela ação do peptídeo. A formação de poros na membrana pelo peptídeo foi proposta como explicação para os resultados encontrados.In the present work, the insecticide recombinant peptide Jaburetox-2Ec, derived from Canavalia ensiformis (Jack bean) urease, was studied, primarily by light and X-ray scattering techniques. Its tendency to aggregate in aqueous solution under different physical-chemical conditions, and its interaction with human platelet mimetic liposome membranes were analyzed. From the data relative to hydrodynamic radii, radii of gyration and mean molecular weight obtained from the peptide in aqueous solution, it was possible to observe a tendency for greater aggregation around pH 5.5, as well as an absence of aggregation at values of pH below 4.0 and above 7.0. No visible effect on the level of aggregation was verified with the addition of reducing agent or ions, whereas the exposure to oxygen in the air resulted in an increase in this level. The studies of Jaburetox-2Ec interaction with liposomes revealed a significant structural change in the membrane, which was shown to be more intense in higher peptide concentrations. Software-assisted theoretical fits were made for the experimental small-angle X-ray scattering curves aiming to quantify the changes in the physical parameters of the membranes caused by peptide action. The formation of pores in the membrane was proposed as an explanation to the results found.
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Lehocká, Nikola. "Agregace hyaluronanu substituovaného palmitoylem". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-376858.
Testo completoAbstract (sommario):
This thesis deals with the aggregation behaviour of palmitoylhyaluronan in two degrees of substitution, namely 10 % and 16 %. Using a fluorescence spectroscopy method with pyrene as a fluorescence probe, we found a critical micellar concentration. The results were confirmed by measuring the dynamic light scattering, which also showed an increase in the size of aggre-gates with an increasing concentration. System stability is reduced by increased ionic strength as evidenced by zeta potential measurement. Experiments found that 16 % substitution sample can form a gel. The gel is very stiff and has excellent properties, which was confirmed by rhe-ology. We also managed to incorporate pyrene in the gel, which was demonstrated by the presence of highly solvated domains that could be polymer micelles. Based on these results, 16% substitution sample was subjected the MTT assay to cytotoxicity. The results confirmed that the examined sample was not toxic.
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Graciani, Guillaume. "Three-dimensional stochastic interferometry : theory and applications to high-sensitivity optical metrology and light scattering amplification Random dynamic interferometer:cavity amplified speckle spectroscopy using a highly symmetric coherent fieldcreated inside a closed Lambertian optical cavity 3D stochastic interferometry detects picometer dynamics of an optical volume Cavity Amplified Speckle Spectroscopy expands lightscattering methods to transparent or miniature samples Super-resolution provided by the arbitrarily strongsuperlinearity of the blackbody radiation". Thesis, Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAX058.
Testo completoAbstract (sommario):
La puissance de la métrologie optique nécessite généralement des géométries simples avec un alignement précis et une phase optique bien contrôlée. Dans cette thèse, nous développons plutôt la notion d'interférométrie du chaos, en utilisant un champ optique ayant un désordre géométrique maximal et une phase aléatoire. Nous montrons que la stochasticité conduit à une très grande sensibilité interférométrique et ouvre la possibilité d'un large éventail de nouvelles mesures optiques et d'une nouvelle méthode que nous appelons la Cavity Amplified Speckle Spectroscopy (Spectroscopie de Speckle Amplifiée par Cavité).L'idée clef est d'injecter un laser monochromatique à très faible bande passante dans une cavité à haute réflectivité Lambertienne, qui agit comme un résonateur aléatoire à gain élevé. On obtient alors un billard Lambertien cohérent en 3D, rempli d'un champ aléatoire 3D statistiquement homogène dans l'espace et invariant par rotation. En tout point P, il peut être décrit comme la superposition cohérente d'un grand nombre d'ondes planes prises au hasard dans une distribution statistique unique qui combine indépendamment (1) une distribution à symétrie sphérique du vecteur d'onde sur une sphère ||k||=k0, avec (2) une distribution uniforme de la phase sur [0,2pi], et (3) un état de polarisation uniformément distribué sur la sphère de Poincarré. Le motif de speckle 3D aléatoire qui en résulte reste constant dans le temps tant que la diffusion de la longueur d'onde du laser peut être négligée. A plus long terme, cependant, il se comporte ergodiquement. Ce travail représente la première réalisation expérimentale de la notion de champ aléatoire 3D proposée par Berry, et il se rapporte également aux recherches sur l'enchevêtrement classique de la lumière. Les concepts de résonateur aléatoire à gain élevé, ou billard lambertien cohérent, correspondent à un nouveau domaine de l’optique, qui n'obéit ni à l'équation d'onde ni à l'équation de diffusion, et devrait conduire à de nouvelles recherches théoriques et expérimentales.En pratique, avec une diffusion suffisamment lente de la phase d'entrée et un bruit de photons suffisamment faible, l'intensité du champ de speckle ne fluctue et ne devient ergodique que si la géométrie de la cavité n'est pas constante, ou si elle contient un milieu avec une distribution de longueurs de chemins optiques ou une polarisation non constante. En utilisant des spectres de décorrélation d'intensité obtenus entre 100 MHz et 0,01 Hz à partir de grains de speckle individuels, nous démontrons la possibilité de mesurer les variations picométriques de la géométrie de la cavité et de détecter sous l’ angstrom le mouvement de diffuseurs en solution. Cette interférométrie volumique du chaos peut également être utilisée pour amplifier des signaux de diffusion auparavant indétectables, et nous montrons un setup miniaturisé de diffusion de la lumière fonctionnant avec des volumes de l’ordre du microlitre et des systèmes quasi-transparents. Un brevet a été déposé pour toute une série d'applications, notamment la détection des vibrations sismiques et acoustiques, la caractérisation du bruit de phase des lasers et la mesure d'échantillons très dilués et peu diffusantsThe power of optical metrology generally requires simple geometries with precise alignment and well controlled optical phases. In the present thesis, we develop instead the notion of chaos interferometry, using an optical field with maximal geometric disorder and phase randomness. We show that stochasticity leads to a very high interferometric sensitivity and opens up the possibility for a wide range of new optical measurements and a new method we call Cavity Amplified Speckle Spectroscopy.The key idea is to inject a very small bandwidth monochromatic laser into a cavity with high albedo Lambertian reflectivity, which acts as a high-gain random resonator. A 3D coherent Lambertian billiard is obtained, filled with a 3D random field that is statistically uniform in space and invariant by rotation. At any given point P, it can be described as the coherent superposition of a large number of plane waves randomly taken from a unique statistical distribution that independently combines (1) a spherically symmetric distribution of the wave vector on a sphere ||k||=k0, with (2) a uniform distribution of the phase on [0,2pi], and (3) a uniformly distributed polarization state on the Poincarré sphere. The resulting random 3D speckle pattern remains constant with time as long as the diffusion of the laser’s wavelength can be neglected. At longer times however, it behaves ergodically. This work represents the first experimental realization of the notion of a 3D random field proposed by Berry, and it also relates to the investigations on classical light entanglement. The concepts of high-gain random resonator, or coherent Lambertian billiard, correspond to a new kind of field in optics, that obeys neither the wave equation nor the diffusion equation, and should lead to new theoretical and experimental investigations.Practically, with a slow enough diffusion of the input phase and a small enough photon-number noise, the speckle intensity field fluctuates and becomes ergodic only if the geometry of the cavity is not constant, or if it contains a medium with a non-constant optical path length distribution or polarization. Using intensity decorrelation spectra obtained between 100 MHz and 0.01 Hz from single speckles, we show the possibility to measure picometer variations of the cavity geometry and to detect sub-angstrom motion of scatterers in solutions. Chaos interferometry can also be used to amplify previously undetectable scattering signals, and we show a miniaturized light scattering setup working with microliter volumes and quasi-transparent systems. A patent was filled for a range of applications including seismic and acoustic vibration sensing, laser phase noise characterization and measurements of highly diluted and poorly scattering samples
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Lepíková, Jana. "Studium vztahu mezi strukturou a reologickými vlastnostmi hydrogelů na makroskopické i mikroskopické úrovni". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2016. http://www.nusl.cz/ntk/nusl-240575.
Testo completoAbstract (sommario):
Diploma thesis main goal is to obtain new pieces of knowledge about relationship between hydrogel structures and its flow and transport properties. Thesis is mainly focusing on combining pertinent biopolymers into model hydrogels based on agarose. Then perform correlation of results obtained by diffusion methods, and by rheologic measurements on macroscopic and microscopic level. Properties of hydrogels were measured by selected rheologic measurements, dynamic light scattering method, and correlative fluorescence spectroscopy. From these methods various parameters (MSD modules, values of complex viscosity) were obtained. Afterwards transport properties of prepared hydrogels were studied by observing Rhodamine 6G diffusion. Here two different approaches were used. From macroscopic perspective, simple principles of mass diffusion from dye solution to cuvettes filled with hydrogels containing individual biopolymers were used. From microscopic perspective, dye was added during the sample preparation and then the mass diffusion was investigated using FCS. Based on evaluated results it was discovered that added biopolymers don’t influence properties of carrier medium, in this case agarose hydrogels. During the study of prepared hydrogels’ reactivity and barrier properties some differences were observed. Charge of biopolymer and its charge density were discovered as main factors influencing transport of charged solutes into prepared hydrogels.
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Dialetachi, Eva Lemmi Giovanini. "Espalhamento dinâmico de luz em sistemas coloidais diluídos". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-20092017-160805/.
Testo completoAbstract (sommario):
A técnica de Espalhamento Dinâmico de Luz (do inglês Dynamic Light Scattering, ou DLS), também conhecida por técnica de Espectroscopia por Correlação de Fótons (do inglês Photon Correlation Spectroscopy, ou PCS), é amplamente utilizada na caraterização estrutural de sistemas coloidais, fornecendo informações importantes sobre tamanhos ca- ractersticos, tempos de correlação e efeitos de polarização no sistema. A facilidade de execução dos experimentos e praticidade das análises é uma das principais vantagens desta técnica. Especificamente para sistemas diludos compostos por partculas em solução, ela pode fornecer informações diretas sobre o raio hidrodinâmico das partculas do meio. No entanto, a obtenção desse parâmetro requer a utilização de métodos de ajuste e análise dos dados experimentais que assumem diversas caractersticas do sistema e possuem li- mitações intrnsecas devido à própria resolução do método frente presença de partculas de variados tamanhos e concentrações, polidispersões contnuas de tamanho, entre vários outros fatores. Existem casos, por exemplo, onde o mesmo conjunto experimental pode ser descrito por dois modelos diferentes. Neste projeto, é proposto um estudo sistemático das limitações dos métodos de análise frente a dados simulados e experimentais, de modo a permitir a aplicabilidade destes métodos a vários tipos de sistemas. Serão investigados casos de sistemas monodispersos e polidispersos, monomodais e multimodais, através da geração de dados simulados que mimetizem a presença desses grupos de partculas, em di- ferentes proporções e polidispersões. Como resultado, teremos indicações da precisão com que estes métodos de modelagem conseguem reproduzir os valores inseridos na simulação. Além disso, experimentos reais serão realizados utilizando amostras padrão de modo a aplicar os métodos de análise a estes dados bem como contrapor os resultados obtidos pelas simulações e pelos dados experimentais.The Dynamic Light Scattering technique, also known as Photon Correlation Spectros- copy, is widely used for the structural characterization for colloidal systems, providing important information on characteristic length scales, correlation times and polarization effects. The relative simple experimental setup and easy-to-use modeling methods are one of the main advantages of this technique. Specifically for diluted systems of particles in solution, one can obtain direct information on the hydrodynamic for the particles in the system. However, in order to retrieve this parameter it is necessary to use modeling and analysis methods for the experimental methods which assumes intrinsic characteristics on the system and have intrinsic limitations due to the resolution of the method when particles with several sizes, concentrations, etc. In several cases, the same experimental data can be described by several different models. In this project it is proposed a systematic study on the limitations on the analysis methods upon simulated and experimental data in order to investigate the applicability of these methods for several system types. Monodisperse and polydisperse systems are investigated, either composed by one type of particles (monomo- dal) or several types of particles (multimodal). As a result, one can obtain indications on the accuracy that the modeling methods can reproduce the simulated parameters. Finally, real experiments were performed using standard samples in order to test the modeling methods and to calibrate the simulation procedures.
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Pihíková, Dominika. "Biopolymerem značené koloidní částice". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216962.
Testo completoAbstract (sommario):
The effect of hydrophobically modified hyaluronan on surfactants aggregation has been studied in this master’s thesis. The value of critical micelle concentration of anionic surfactant SDBS (sodium dodecylbenzensulfonate), cationic surfactant CTAB (cetyltrimethylamonnium bromide) and nonionic surfactant Triton X-100 (octylphenol ethoxylate) was determined by fluorescence spectroscopy using pyrene probe. Aggregation behavior of surfactants was performed with addition of hydrophobically modified hyaluronan of two molecular weights (17 kDa, 206 kDa) in aqueous solution. The greatest influence of hydrophobized hyaluronan on aggregation behavior was observed in system with cationic surfactant CTAB. Stability of system containing cationic surfactant and hydrophobically modified hyaluronan was established through zeta potential. Last part of thesis deals with size determination using dynamic light scattering.
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Bruzadin, Felipe Rodrigues. "Sequência didática sobre dispersão e difração da luz : confecção e utilização de um espectroscópio /". Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/158284.
Testo completoAbstract (sommario):
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este trabalho apresenta uma sequência didática onde são utilizadas ferramentas de informática e a experimentação como recursos metodológicos, com o intuito de contribuir com o ensino e a prática em sala de aula dos professores. Na sequência, aparece a ordem de como trabalhar a dispersão e a difração da luz, assim como as habilidades e competências necessárias, levando em conta os conhecimentos prévios dos alunos. Os resultados nos mostram que os alunos conseguiram entender a relação entre o espectro e a luz fornecida por diferentes lâmpadas assim como a participação deles nas atividades foi relevante.
This work presents a didactic sequence in which computer tools and experimentation are used as methodological resources, with the aim of contributing to teaching and practice in the teachers' classroom. In the sequence, appears the order of how work the scattering and diffraction of light, as well as the skills and competencies necessary, taking into account the prior knowledge of students. The results show us that students understand the relationship between the spectrum and the light supplied by different light bulbs as well as their participation in activities was relevant.
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Kratochvíl, Zdeněk. "Optimalizace postupu izolace a charakterizace amorfních PHB granulí". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316175.
Testo completoAbstract (sommario):
First artificial PHB granules were prepared under the terms of this thesis. The effect of used PHB solvent, ultrasonic bath temperature and time, solvent evaporation temperature and stabilizing agent nature was investigated using dynamic and electrophoretic light scattering. The most proper parameters were demonstrated at samples which were prepared by dissolving of PHB in chloroform, stabilizing with CTAB or lecithin, ultrasonifying at 35 °C followed by chloroform evaporating at 60 °C. Based on ATR-FTIR and Raman spectroscopy results, it was found out that PHB within the artificial granules were in crystalline form. The native PHB granules were isolated from Cupriavidus necator using either lysosyme, deoxyribonuclease and cell disruption by ultrasonification or digestion with alcalase, SDS and EDTA. Granules obtained by both isolation procedures were characterized by ATR-FTIR, Raman spectroscopy, light scattering techniques and DSC. According to the analyses results, the second mentioned procedure turned out to be more effective for obtaining the polymer in amorphous state. Furthermore, the polymer within granules recovered by using this procedure was thermally more stable. Last but not least, the native PHB granules samples were exposed to effect of acetone, lipase and sodium hypochlorite, assuming that polymer crystallinity should be increased by these chemicals in varying degrees. The highest degree of crystallinity was achieved after their treatment with lipase.
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Warell, Johan. "Regolith Properties of Mercury Derived from Observations and Modelling". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://publications.uu.se/theses/91-554-5535-2/.
Testo completo
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Groth, Mike Christopher. "Investigation of the Linker Region of Coiled Coil SNARE-Analoga and Membrane Composition on Vesicle Fusion". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://hdl.handle.net/21.11130/00-1735-0000-0005-159B-5.
Testo completo
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Mikušová, Janka. "Gelace mucinu – příprava artificiálních modelů pro studium biologických mukózních systémů". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449398.
Testo completoAbstract (sommario):
The scope of this masters thesis is the preparation of a model mucin system and its utilization as an artificial model of the native mucus system. The creation of this model system, according to several designed methods was a part of experimental part of the thesis. The preparation of mucin system comprised of physical and chemical methods of hydrogel formation, screening and characterisation of the various physical conditions of the mucin properties on its molecular level, and the preparation of sorbent with sorption surface containing mucin. Methods of light scattering, namely dynamic light scattering (DLS), used for mucin particles size change monitoring, and electroforetic light scattering (ELS), used for Zeta potential change monitoring, were used for the screening of the impact of physical factors on the properties of mucin.For the characterisation of impact of the temperature on changes in mucin sctructure was, apart from monitoring of light scattering, used also a diferential scanning calorimetry (DSC), which registered temperature value, at which mucin thermal denaturation occurs. In the next part of the thesis we subdued the created sorption surfaces to various physical-chemical analyses, which task is the characterisation and projection of surface and confirmation of mucin presence.Substancial part in monitoring and characterisation of changes in surface sctructure of sorption surface was accomplished by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscophy (SEM) was used for the final, more detailed, projection of the mucin enriched, sorbent surface structure. Suggested methods of mucin hydrogel, didnt prove sufficient results for the possibility of application of hydrogel as a artificial model of real mucus system, but the sorbent application was indicated as a suitable alternative and an instrument for the further mucin behaviour research and possibly subsequent bacterial adhesion, which represents the first step in the formation of the bacterial biofilm.
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Píšová, Denisa. "Studium transportních procesů v hydrogelech pomocí mikroreologických technik". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316166.
Testo completoAbstract (sommario):
This diploma thesis is focused on the determintaion of viscoelastic properties of agarose hydrogels containing different polyelectrolytes by microrheological and macrorheological techniques. From microrheological techniques the dynamic light scattering was used. Firstly, the influence of different polyelectrolyte volume was studied. Then the effect of variously charged polyelectrolyte and ionic strenght on microrheological properties of agarose hydrogels were determined. Classic rheology was used to compare the results obtained using the DLS microrheology method. Finally, the results from macro- and microrheology were correlated with each other.
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Råsmark, Per Johan. "On the Structure and Dynamics of Polyelectrolyte Gel Systems and Gel-surfactant Complexes". Doctoral thesis, Uppsala universitet, Fysikalisk-kemiska institutionen, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4652.
Testo completoAbstract (sommario):
This thesis describes the results of experimental work on polyelectrolyte gels and their interaction with oppositely charged surfactants, and presents two new algorithms applicable to the simulation of colloid and polymer systems. The model systems investigated were crosslinked poly(acrylate) (PA) and poly(styrene sulphonate) (PSS), and the surfactant was dodecyl trimethylammonium bromide (DoTAB). Pure gel materials were studied using dynamic light scattering. It was shown that the diffusion coefficient (D) increases with increasing degree of swelling and the concentration dependence is larger than predicted by scaling arguments. For gels at swelling equilibrium D increases with increasing degree of crosslinking. In subsequent studies on gel particles in DoTAB solution, Raman spectra were recorded at different positions in the gel. For both types of gels two distinct regions could be observed. For PA the surfactant is localised in the outer phase without any surfactant in the core, while for PSS the surfactant was distributed such that it had the same concentration relative to the polymer throughout the gel. In a second experiment, the kinetics for the deswelling of microscopic PSS particles in DoTAB solution was studied. It was found that the final volume varied linearly with the DoTAB concentration, and the rate of volume decrease could be fitted to a single exponential indicating stagnant layer diffusion to be the rate limiting process for the deswelling of the PSS particles. In the second part, I first describe an algorithm showing an efficient way to detect percolation in simulations, with periodic boundary conditions, using recursion. Spherical boundary conditions is an alternative to periodic boundary conditions for systems with long-range interactions. In the last part, the possibility to use the surface of a hypersphere in four dimensions for simulations of polymer systems is investigated, and algorithms for Monte Carlo and Brownian dynamics simulations are described.