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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Polymers at membranes

Breidenich, Markus January 2000 (has links)
Die Oberfläche biologischer Zellen besteht aus einer Lipidmembran und einer Vielzahl von Proteinen und Polymeren, die in die Membran eingebaut sind. <br /> Die Beeinflussung der Membran durch Polymere, die mit einem Ende an der Membran verankert sind, wird im Rahmen dieser Arbeit anhand eines vereinfachten biomimetischen Systems studiert.<br/> Der entropische Druck, den das Polymer durch Stöße auf die Membran ausübt, führt dazu, dass sich die Membran vom Polymer weg krümmt. Die resultierende Membranform ist ein Kegel in der Nähe des Ankers und ein Katenoid in grossem Abstand vom Ankerpunkt. Monte Carlo-Simulationen bestätigen die perturbativ berechneten Resultate. <br/> Bei Hinzunahme eines attraktiven Potentials zwischen Polymer und Membran verringert sich die ursprünglich vom Polymer induzierte Krümmung. Im Limes starker Adsorption, in welchem das Polymer ganz auf der Membranoberfläche lokalisiert ist, verschwindet der Polymerdruck und die durch diesen induzierte Krümmung der Membran. Falls das Polymer nicht direkt auf der Membranoberfläche verankert ist, sondern in endlichem Ankerabstand, biegt sich die Membran im adsorbierten Fall zum Polymer hin. <br /> Im letzten Teil der Arbeit werden nicht verankerte Polymere in Lösung betrachtet. Untersucht wird der Einfluss einer solchen Polymerlösung auf die Krümmung der Membran. Im Grenzfall einer rein sterischen, repulsiven Wechselwirkung zwischen Polymeren und Membran biegt sich diese, im Gegensatz zur verankerten Situation, zur Lösung hin. Bei zunehmender Attraktion biegt sich die Membran im Limes starker Adsorption der Polymere von der Lösung weg. / The surface of biological cells consists of a lipid membrane and a large amount of various proteins and polymers, which are embedded in the membrane or attached to it. <br/> We investigate how membranes are influenced by polymers, which are anchored to the membrane by one end. The entropic pressure exerted by the polymer induces a curvature, which bends the membrane away from the polymer. The resulting membrane shape profile is a cone in the vicinity of the anchor segment and a catenoid far away from it. The perturbative calculations are confirmed by Monte-Carlo simulations. <br/> An additional attractive interaction between polymer and membrane reduces the entropically induced curvature. In the limit of strong adsorption, the polymer is localized directly on the membrane surface and does not induce any pressure, i.e. the membrane curvature vanishes. If the polymer is not anchored directly on the membrane surface, but in a non-vanishing anchoring distance, the membrane bends towards the polymer for strong adsorption.<br/> In the last part of the thesis, we study membranes under the influence of non-anchored polymers in solution. In the limit of pure steric interactions between the membrane and free polymers, the membrane curves towards the polymers (in contrast to the case of anchored polymers). In the limit of strong adsorption the membrane bends away from the polymers.
12

Tests zur Modellspezifikation in der nichtlinearen Regression

Bartels, Knut January 1999 (has links)
Als Grundlage vieler statistischer Verfahren wird der Prozess der Entstehung von Daten modelliert, um dann weitere Schätz- und Testverfahren anzuwenden. Diese Arbeit befasst sich mit der Frage, wie diese Spezifikation für parametrische Modelle selbst getestet werden kann. In Erweiterung bestehender Verfahren werden Tests mit festem Kern eingeführt und ihre asymptotischen Eigenschaften werden analysiert. Es wird gezeigt, dass die Bestimmung der kritischen Werte mit mehreren Stichprobenwiederholungsverfahren möglich ist. Von diesen ist eine neue Monte-Carlo-Approximation besonders wichtig, da sie die Komplexität der Berechnung deutlich verringern kann. Ein bedingter Kleinste-Quadrate-Schätzer für nichtlineare parametrische Modelle wird definiert und seine wesentlichen asymptotischen Eigenschaften werden hergeleitet. Sämtliche Versionen der Tests und alle neuen Konzepte wurden in Simulationsstudien untersucht, deren wichtigste Resultate präsentiert werden. Die praktische Anwendbarkeit der Testverfahren wird an einem Datensatz zur Produktwahl dargelegt, der mit multinomialen Logit-Modellen analysiert werden soll. / The data generating process often is modeled as a basis for many subsequent statistical estimation and testing procedures. In this work the question is studied, how this specification of parametric models itself can be tested. In generalization of existing methods, tests with fixed kernel are introduced and their asymptotics are analyzed. It is shown that the determination of critical values is possible using several resampling procedures. Of these a new Monte-Carlo-approximation is of special importance, since it can reduce the complexity of calculation substantially. A conditional least squares estimator for nonlinear models is defined and its essential asymptotic properties are derived. All versions of the tests and all new concepts were studied in simulation studies and the most important results are presented. The applicability of the tests is demonstrated with a dataset on product choice that is to be analyzed with multinomial logit models.
13

Adsorptionsschichten an fluiden Grenzflächen : Skalengesetze und Ionenverteilungen

Teppner, Randolf January 2000 (has links)
In dieser Arbeit wurden zwei Themenbereiche bearbeitet: <br /> 1. Ellipsometrie an Adsorpionsschichten niedermolekularer Tenside an der Wasser/Luft-Grenzfläche (Ellipsometrie ist geeignet, adsorbierte Mengen von nicht- und zwitterionischen Tensiden zu messen, bei ionischen werden zusätzlich die Gegenionen mit erfaßt; Ellipsometrie mißt sich ändernde Gegenionenverteilung).<br /> 2. Ellipsometrische Untersuchung von endadsorbierten Polymerbürsten an der Wasser/Öl-Grenzfläche (Ellipsometrie ist nicht in der Lage, verschiedene Segmentkonzentrationsprofile innerhalb der Bürste aufzulösen, ist aber sehr wohl geeignet, Skalengesetze für Dicken und Drücke in Abhängigkeit von Ankerdichte und Kettenlänge der Polymere zu überprüfen; für in Heptan gequollene Poly-isobuten-Bürsten konnte gezeigt werden, daß sie sich entsprechend den theoretischen Vorhersagen für Bürsten in einem theta-Lösungsmittel verhalten) / In this publication two subjects are dealt with:<br /> 1. Ellipsometry on adsorption layers of low molecular weight surfactants at the air/water-interface (Ellipsometry is suitable to measure adsorbed amounts of non-ionic surfactants, whereas this is impossible for ionic surfactants; in the latter case the ellipsometric signal is strongly influenced by the counter ion distribution; ellipsometry can measure changes in the counter ion distribution)<br /> 2. Ellipsometric investigation of polymer brushes anchored to the oil/water-interface (Ellipsometry is not able to distinguish between different segmental concentration profiles within the brush, but it is nevertheless suitable to check scaling laws for brush height and pressure in dependence on anchor density and degree of polymerization of the polymers; it could be shown, that brushes of poly-isobutylene swollen in heptane behave as predicted for brushes in a theta-solvent)
14

Cosmological applications of gravitational lensing

Schmidt, Robert W. January 2000 (has links)
In dieser Arbeit benutze ich den Gravitationslinseneffekt als ein Werkzeug, um zwei recht unterschiedliche kosmologische Fragestellungen zu bearbeiten: die Natur der dunklen Materie in Galaxienhalos und die Rotation des Universums. Zuerst untersuche ich den Mikrolinseneffekt in den Gravitationlinsensystemen Q0957+561 und Q2237+0305. In diesen Systemen scheint das Licht eines Quasars durch die Linsengalaxie hindurch. Aufgrund der Relativbewegung zwischen Quasar, Linsengalaxie und Beobachter verursachen kompakte Objekte innerhalb der Galaxie oder dem Galaxienhalo Helligkeitsfluktuationen des Hintergrundquasars. Ich vergleiche die am 3.5m Teleskop des Apache Point Observatory zwischen 1995 und 1998 gewonnene Lichtkurve des Doppelquasars Q0957+561 (Colley, Kundic & Turner 2000) mit numerischen Simulationen, um zu untersuchen, ob der Halo der Linsengalaxie aus massiven kompakten Objekten (MACHOs) besteht. Dieser Test wurde zuerst von Gott (1981) vorgeschlagen. Ich kann MACHO-Massen von 10^-6 M_sun bis zu 10^-2 M_sun ausschliessen, sofern der Quasar kleiner ist als 3x10^14 h_60^-0.5 cm und MACHOs mehr als 50% des dunklen Halos ausmachen. Im zweiten Teil der Arbeit stelle ich neue Beobachtungsdaten fuer den Vierfachquasar Q2237+0305 vor, die am 3.5m Teleskop des Apache Point Observatory zwischen Juni 1995 und Januar 1998 gewonnen wurden. Obwohl die Daten bei veraenderlichen, oft schlechten Seeing Bedingungen und grober Pixelaufloesung aufgenommen wurden, ist die Photometrie der beiden helleren Quasarbilder A und B mit Hilfe von HST-Beobachtungen moeglich. Ich finde ein Helligkeitsmaximum in Bild A mit einer Amplitude von 0.4 bis 0.5 mag und einer Dauer von wenigstens 100 Tagen. Dies zeigt, dass in der Linsengalaxie der Mikrolinseneffekt stattgefunden hat. Im abschliessenden Teil der Arbeit benutze ich dann den schwachen Gravitationslinseneffekt, um Grenzen fuer eine Klasse von rotierenden Kosmologien vom Goedel-Typ zu ermitteln, die von Korotky & Obukhov (1996) beschrieben wurde. In Studien des schwachen Linseneffektes werden die Formen von tausenden von Hintergrundgalaxien vermessen und gemittelt. Dabei werden kohaerente Verzerrungen der Galaxienformen gemessen, die von Massenverteilungen im Vordergrund oder von der grossraeumigen Struktur der Raumzeit selbst verursacht werden. Ich berechne die vorhergesagte Scherung als Funktion der Rotverschiebung in rotierenden Kosmologien vom Goedel-Typ und vergleiche diese mit der oberen Grenze fuer die kosmische Scherung gamma_limit von 0.04, die in Studien des schwachen Linseneffektes gewonnen wurde. Dieser Vergleich zeigt, dass Modelle vom Goedel-Typ keine groesseren Rotationen omega als H_0=6.1x10^-11 h_60/Jahr haben koennen, wenn die Grenze fuer die kosmische Scherung fuer den ganzen Himmel gilt. / In this thesis we use the gravitational lensing effect as a tool to tackle two rather different cosmological topics: the nature of the dark matter in galaxy halos, and the rotation of the universe. Firstly, we study the microlensing effect in the gravitational lens systems Q0957+561 and Q2237+0305. In these systems the light from the quasar shines directly through the lensing galaxy. Due to the relative motion of the quasar, the lensing galaxy, and the observer compact objects in the galaxy or galaxy halo cause brightness fluctuations of the light from the background quasar. We compare light curve data from a monitoring program of the double quasar Q0957+561 at the 3.5m telescope at Apache Point Observatory from 1995 to 1998 (Colley, Kundic & Turner 2000) with numerical simulations to test whether the halo of the lensing galaxy consists of massive compact objects (MACHOs). This test was first proposed by Gott (1981). We can exclude MACHO masses from 10^-6 M_sun up to 10^-2 M_sun for quasar sizes of less than 3x10^14 h_60^-0.5 cm if the MACHOs make up at least 50% of the dark halo. Secondly, we present new light curve data for the gravitationally lensed quadruple quasar Q2237+0305 taken at the 3.5m telescope at Apache Point Observatory from June 1995 to January 1998. Although the images were taken under variable, often poor seeing conditions and with coarse pixel sampling, photometry is possible for the two brighter quasar images A and B with the help from HST observations. We find independent evidence for a brightness peak in image A of 0.4 to 0.5 mag with a duration of at least 100 days, which indicates that microlensing has taken place in the lensing galaxy. Finally, we use the weak gravitational lensing effect to put limits on a class of Goedel-type rotating cosmologies described by Korotky & Obukhov (1996). In weak lensing studies the shapes of thousands of background galaxies are measured and averaged to reveal coherent gravitational distortions of the galaxy shapes by foreground matter distributions, or by the large-scale structure of space-time itself. We calculate the predicted shear as a function of redshift in Goedel-type rotating cosmologies and compare this to the upper limit on cosmic shear gamma_limit of approximately 0.04 from weak lensing studies. We find that Goedel-type models cannot have larger rotations omega than H_0=6.1x10^-11 h_60/year if this shear limit is valid for the whole sky.
15

Untersuchung der Acetyl-Coenzym A:alpha-Glucosaminid N-Acetyltransferase in gereinigten lysosomalen Membranen / x

Bodammer, Beatrice 27 April 2012 (has links)
No description available.
16

A metapoesia na obra de Florbela Espanca e Cecília Meireles

Silvia Helena Miguel Trevisan 01 June 2007 (has links)
Nesta tese de doutoramento, estudaremos a metalinguagem poética de Florbela Espanca e Cecília Meireles que vai compor o discurso de ambas. Considerando a reflexão sobre a criação poética a partir de Aristóteles, tomaremos sua Poética para observar a variação conceitual que se processou até hoje. Verificaremos como em Florbela Espanca e em Cecília Meireles se incorpora tal conceito à luz da perspectiva de poetas modernos como Baudelaire, Rimbaud, Mallarmé. Deste modo, tanto Florbela quanto Cecília levantam problemas de linguagem ou de produção literária na poesia, conforme postulou Jakobson em Lingüística e poética, levando-se em conta, também, a capacidade decodificadora do receptor na esteira de Terry Eagleton. Procuraremos mostrar como se revela, na obra das poetisas, o discurso feminino, que, na busca empreendida pela mulher, ao encalço de sua própria imagem e de seu lugar no mundo, se implicita a compreensão do fazer poético. / In this thesis, we will study the poetical metalanguage of Florbela Espanca and Cecília Meireles which examines their speeches in detail. Considering the reflection on the poetical creation by Aristotle, we will use his Poetic to observe the conceptual variation that has been developed until today. We will verify that Florbela Espanca and Cecília Meireles incorporated such concepts as the perspective light of modern poets, like Baudelaire, Rimbaud and Mallarmé. Thus, Florbela as well as Cecília brought up language problems or literary production in poetry, as postulated Jakobson in Linguistcs and Poetry, taking into account the decoding capacity of the receptor according to Terry Eagleton. We show how it is demonstrated in the work of the poetesses the female speech, in the search undertaken by woman seeking her own image and her place in the world. It implies the understanding of writing poetry.
17

A metapoesia na obra de Florbela Espanca e Cecília Meireles

Trevisan, Silvia Helena Miguel 01 June 2007 (has links)
Nesta tese de doutoramento, estudaremos a metalinguagem poética de Florbela Espanca e Cecília Meireles que vai compor o discurso de ambas. Considerando a reflexão sobre a criação poética a partir de Aristóteles, tomaremos sua Poética para observar a variação conceitual que se processou até hoje. Verificaremos como em Florbela Espanca e em Cecília Meireles se incorpora tal conceito à luz da perspectiva de poetas modernos como Baudelaire, Rimbaud, Mallarmé. Deste modo, tanto Florbela quanto Cecília levantam problemas de linguagem ou de produção literária na poesia, conforme postulou Jakobson em Lingüística e poética, levando-se em conta, também, a capacidade decodificadora do receptor na esteira de Terry Eagleton. Procuraremos mostrar como se revela, na obra das poetisas, o discurso feminino, que, na busca empreendida pela mulher, ao encalço de sua própria imagem e de seu lugar no mundo, se implicita a compreensão do fazer poético. / In this thesis, we will study the poetical metalanguage of Florbela Espanca and Cecília Meireles which examines their speeches in detail. Considering the reflection on the poetical creation by Aristotle, we will use his Poetic to observe the conceptual variation that has been developed until today. We will verify that Florbela Espanca and Cecília Meireles incorporated such concepts as the perspective light of modern poets, like Baudelaire, Rimbaud and Mallarmé. Thus, Florbela as well as Cecília brought up language problems or literary production in poetry, as postulated Jakobson in Linguistcs and Poetry, taking into account the decoding capacity of the receptor according to Terry Eagleton. We show how it is demonstrated in the work of the poetesses the female speech, in the search undertaken by woman seeking her own image and her place in the world. It implies the understanding of writing poetry.
18

Flüssigkristalline Polyfluorene

Nothofer, Heinz-Georg January 2001 (has links)
Eine Reihe 9,9-dialkylsubstituierter Polyfluorene mit linearen und verzweigtkettigen Alkylsubstituenten und einem Molekulargewicht von bis zu 200000 g/mol wurde synthetisiert und charakterisiert. Darüber hinaus wurden einige dieser Polymere mit einer geeigneten 'Lochtransport'-Funktionalität (Triphenylamin-Derivate) ausgestattet, um die Ladungstransporteigenschaften und das Molekulargewicht dieser Substanzen zu kontrollieren. Die thermische Orientierung dieser neuen Polymere auf geriebenen Polyimid-Schichten führte zu hoch anisotropen Filmen mit großen dichroischen Verhältnissen (Absorption parallel und senkrecht zur Reibungsrichtung gemessen). Ferner wurde eine Gruppe chiraler Polyfluorene synthetisiert und hinsichtlich ihrer chiroptischen Eigenschaften untersucht. Der mit diesen chiralen, konjugierten Polymeren erreichte Grad der Anisotropie in Absorption (CD), circular polarisierter Photolumineszenz (CPPL) und Elektrolumineszenz (CPEL) überstieg die bis dahin bekannten Werte um einen Faktor von 200. / A series of 9,9-dialkyl-poly(fluorene-2,7-diyl)s containing linear and branched alkyl substituents with a molecular weight of up to 200000 g/mol has been synthesized and characterized. Moreover, some of the polymers were end capped with a suitable hole transport functionality, such as a triphenylamine derivative, to improve their charge transport properties and to control the molecular weight. The thermal alignment of these novel polymers on a rubbed polyimide layer led to highly anisotropic film formation with large dichroic ratios (absorption parallel and perpendicular to the rubbing direction). Additionally a set of chiral polyfluorenes has been synthesized and investigated with respect to their chiroptical properties. The degrees of anisotropy in absorption (CD), circular polarized photoluminescence (CPPL) and electroluminescence (CPEL) found with these chiral conjugated polymers exceeded the yet known values by a factor of 200.
19

The Book of Jeremiah : Jeremiah 30:5 to 31:22 and the Jeremiah tradition

Cox, David Elmer January 1993 (has links)
David Elmer Cox's thesis is a form critical study of the salvation/deliverance/hope poetic, prophetic oracles of the Hebrew Scriptures. Beginning with the archaeological concepts of pottery dating and stratigraphic analysis, Cox presents a methodology he classifies "Gattungen dating". Just as pottery forms are able to be used for dating purposes because of the continuous and measurable changes which developed in pottery as the needs and living circumstances of people changed, Cox proposes that the Gattungen utilized by the prophets of Israel proclaiming poetic salvation/ deliverance/hope oracles might also be used as a dating device because of continuous and measurable changes in oral address. Just as with pottery forms, Cox subjects the poetic salvation/deliverance/hope oracles of the Hebrew Scriptures to typological classification and chronological ordering. Isolating the salvation/deliverance/hope oracles outside of Jeremiah into pre-exilic, exilic and post-exilic period categories, Cox presents an evolutionary pattern of development within the salvation/deliverance/hope poetic, prophetic announcements (chapter two). Then, examining two passages scholars consider authentic Jeremiah (3:12b-13; 4:1-2), he applies the Gattungen dating methodology to determine that Jeremiah's salvation/deliverance/hope speeches reflected the concerns and Gattungen of the pre-exilic prophets (chapter three). Cox then examines the central nucleus of poetic salvation/deliverance/hope material within Jeremiah, 30(37):5-31(38):22, a section much debated as to its dating and Sitz im Leben. He determines that the Gattungen utilized by the poetic consolation collection are from a time later than Jeremiah of Anathoth. Through Gattungen dating procedure and historical-critical methodology, Cox proposes that 30(37):5-31(38):22 was a separate poetic collection which attained a recognizable textual shape in the early post-exilic period (chapter four). Cox proposes that the poetic consolation collection is an example of deutero-prophetic activity (chapter five).
20

Microencapsulation of clove essential oil with gelatin and alginate

Kopp, Victoria V., Agustini, C. B., dos Santos, J. H. Z., Gutterres, M. 26 June 2019 (has links)
Content: Essential oils are of commercial interest primarily because of their potential antimicrobial, antifungal and antioxidant properties and for being of natural origin, which generally represents lower risk to the environment and human health. Clove essential oil not only contains many kinds of biological active compositions but also has highly effective and comprehensive antibacterial functions. Remarkably, clove has strong antimicrobial activities against a wide range of pathogenic microorganisms. To prevent chemical changes the oil is microencapsulated. The aim of this study is to develop essential oil microcapsules with gelatin and alginate. Various solutions were prepared for the capsule wall material at different concentrations. The encapsulation efficiency (%) was accessed and the microcapsules were characterized by oil content (%), oil charge (%), morphology, functional groups present, thermogravimetric analysis and by Fourier transform - infrared spectral analysis. FT-IR spectra of the clove oil shows some special peaks at 1148,01 and 1033,33 cm-1. The spectra of the capsule showed peaks 1148.34 and 1033.29 cm -1, the same peaks present in clove oil, showing that the encapsulation did not alter the structure of the oil's main assets. In case of the gelatin and alginate microcapsules containing clove oil, most of the characteristic peaks of clove oil remained unchanged, indicating the successful incorporation of clove oil into the microcapsules and the chemical stability of the clove oil after encapsulation. In otherwords, there was no significant chemical interaction between the oil and the wall of the microcapsule. Take-Away: The clove oil was microencapsulated according the FTIR spectra.

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