During the period January 2001 to January 2003, M Sc student Mr Tleyane Jonas Sono developed an apparatus to measure the pressure- and temperature-dependence of the electro-optic Kerr effect (electric-field-induced birefringence) in gases. Mr Sono presented experimental results for dimethyl ether at a wavelength of 632.8 nm, extracting polarizability tensor components, first and second Kerr hyperpolarizabilities, and second Kerr-effect virial coefficients for this molecular species. This thesis has been primarily concerned with a thorough re-investigation of the Keneffect for the dimethyl ether molecule. Of primary concern is the reproducibility of the measured data, which depend upon precise and accurate knowledge of various experimental parameters. These include calibrations of the high-voltage power supply which is used to establish the electric field across the medium, the pressure transducer, the platinum thermistors, as well as the Faraday cell which forms the heart of the compensator. There is also a possibility of the 316-stainless-steel electrodes buckling and warping as they are cycled over ±200°C, leading to variations in the applied field and a consequent hysteresis in the results. In essence, we have been loath to publish our Kerr-effect investigation of dimethyl ether before making a thorough investigation of the reproducibility of our measured data. Here we present our investigations, and compare our new Kerr virial coefficients and the molecular (hyper)polarizability data extracted from them against the previous work of Sono. It will become apparent agreement is excellent, and that the findings for dimethyl ether are now ready for publication. The molecular-tensor theory of the Kerr-effect; including the second Kerr-effect virial coefficient BK, which describes the effects of intermolecular collisions on the molecular Kerr constant; is reviewed. The computed data is compared with the experimental data, yielding good agreement over the full experimental temperature range of 280 to 450 K. Attempts to obtain measured data at 260 K proved fruitless in the present study, though efforts are underway to complete this task. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

No description available.

Zugl.: Bochum, Univ., Diss., 2007

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 159-163). Also available via the Internet.

University, Diss., 1998--Duisburg. / Dateiformat: zip, elektronische Ressource verfügbar im PDF- und Word-Format.

Techn. Universiẗat, Diss., 2001--Dresden.

Thesis (Ph. D.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (p. 118-135). Also available via the World Wide Web.

Proefschrift Rijksuniversiteit Groningen. / Met lit.opg. - Met samenvatting in het Nederlands.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, 2014. / Submitted by Ana Cristina Barbosa da Silva (annabds@hotmail.com) on 2014-11-28T18:48:47Z No. of bitstreams: 1 2014_VictorBarbosaJatoba.pdf: 494161 bytes, checksum: 7174c33026d49eca514696d934078d3a (MD5) / Approved for entry into archive by Patrícia Nunes da Silva(patricia@bce.unb.br) on 2014-12-01T15:00:10Z (GMT) No. of bitstreams: 1 2014_VictorBarbosaJatoba.pdf: 494161 bytes, checksum: 7174c33026d49eca514696d934078d3a (MD5) / Made available in DSpace on 2014-12-01T15:00:10Z (GMT). No. of bitstreams: 1 2014_VictorBarbosaJatoba.pdf: 494161 bytes, checksum: 7174c33026d49eca514696d934078d3a (MD5) / O tema desta dissertação é o Teorema de Robinson, que trata da relação entre os chamados campos eletromagnéticos nulos e as congruências de geodésicas nulas shear-free no espaço de Minkowski. Atualmente, muito tem sido feito nos estudos de propriedades topológicas de campos eletromagnéticos nulos, como feito por W. Irvine em 2008 e H. Kedia 2013. Além disso, Adamo e Newman, em 2009, utilizaram as congruências de geodésicas nulas shear-free para o estudo e interpretação de problemas relacionados com a relatividade geral. Estes estudos são baseados no Teorema de Robinson, que relaciona toda congruência de geodésicas nulas shear-free com uma família de campos eletromagnéticos nulos e, reciprocamente, todo campo eletromagnético nulo com uma congruência nula de geodésicas shear-free, e o Teorema de Kerr, que caracteriza toda congruência de geodésicas nulas como os zeros de uma função analítica arbitrária. _______________________________________________________________________________ ABSTRACT / The theme of this work is the relation between null electromagnetic fields and congruence of null geodesic shear-free in Minkowski space-time, known as the Robinson Theorem. Recently studies have been done about topologic properties of null electromagnetic fields, such as W. Irvine in 2008 and H. Kedia 2013. Also, Adamo and Newman, in 2009, used the congruence of null geodesic shear-free to study and understand problems related to General Relativity. These studies are based in Robinson’s Theorem, which states that each congruence of null geodesic shear-free is related to a family of null electromagnetic fields and, conversely, each null electromagnetic field is related to a congruence of null geodesic shear-free, and Kerr’s Theorem, which relates a congruence of null geodesic shear-free to the zeros of an arbitrary analytic function.

La nanotecnología ha permitido avanzar sobre cuestiones que parecían impen- sadas, abriendo un nuevo campo de investigación básica y tecnológica. Su aplicación en la medicina no ha sido una excepción y la fabricación de sistemas nanoestructurados para transporte y liberación controlada de fármacos ha surgido como una alternativa promisoria para el tratamiento de enfermedades tales como el cáncer o el Alzheimer. Sin embargo, la diversidad de las patologías de paciente a paciente provocan que se deba tener un control preciso de la ingeniería de estos nanotransportadores de forma de dar versatilidad y eficiencia a los tratamientos. Dentro de la variedad de estos sistemas emergen los complejos basados en polímeros ya que debido a su biocompatibilidad, so- lubilidad y potencial responsividad a estímulos se convierten en excelentes candidatos para su aplicación en nanomedicina. Por ello, este trabajo de tesis se aboca al estudio de mezclas en solución acuosa de polielectrolitos y moléculas pequeñas de diversa índole, tales como tensoactivos, sales o agentes terapéuticos; junto con los complejos nanoestructurados que surgen de la misma. Por un lado se pretende abordar una caracterización fisicoquímica del proceso de ensamblado y las propiedades de los complejos resultantes; y por otro evaluar su utilización potencial como nanotransportadores de fármacos. Para tal fin, se han utilizado una gran diversidad de técnicas experimentales, tanto para caracterización volumétrica como interfacial. Entre ellas se destaca la implementación de la técnica de Efecto Kerr Electroóptico desarrollada en el curso de esta tesis. En primer lugar se utilizará un sistema compuesto de polielectrolitos aniónicos y la droga anticancerosa hidrocloruro de doxorrubicina para determinar las propiedades dieléctricas locales en sistemas de multicapas de polielectrolitos. También se presenta- rán dos sistemas responsivos a pH. El primero, mezcla de ácido poliacrílico (PAA) y el tensoactivo catiónico no comercial Gemini 12-2-12, se caracterízará en superficie y en volumen demostrándose que las interacciones polímero-surfactante dominan y determi- nan la estructura de agregados. Los mismos pueden ser modulados con el pH de forma de obtener un sistema responsivo a estímulos. El segundo sistema responsivo surge de la mezcla de hidrocloruro de polialilamina (PAH) y sales de polifosfato. A través de caracterizaciones morfológicas y termodinámicas se explicará y concluirá que la canti- dad de grupos fosfato es determinante en la responsividad; obteniéndose nanopartículas con distintos rangos de estabilidad frente al pH. Finalmente, como sistema modelo de terapias génicas, se mostrarán resultados de un sistema mezcla de ácido desoxirribonu- cléico (ADN) con un tensoactivo catiónico como el bromuro de dodeciltrimetilamonio (DTAB). El proceso de ensamblado y las interacciones que las producen en conjunto con las variaciones morfológicas se seguirán con Efecto Kerr Electroóptico. / Nanotechnology has made possible to advance on issues that years ago seemed unthinkable, opening up a new field for scientific and technological research. Its appli- cation in medicine has not been the exception and the manufacture of nanostructured systems for transport and controlled release of drugs has emerged as a promising alter- native to treatment of diseases such as cancer or Alzheimer. However, pathologies varies from patient to patient and consequently, the engineering of these nanocarriers must be precisely controlled in order to give versatility and efficiency to the treatments. Within the variety of carriers, polymer-based complexes emerge; due to their biocompatibility, solubility and potential responsiveness to stimuli they become plausible candidates for their application in nanomedicine. Therefore, this thesis work focuses on the study of mixtures in aqueous solution of polyelectrolytes and small molecules of various kinds, such as surfactants, salts or therapeutic agents, together with the nanostructured complexes that arise from them. On the one hand, it is intended to get a physicochemical characterization of the assembly process and the properties of the resulting complexes; and on the other hand, to evaluate their potential as drug nanocarriers. To achive this aim, a wide range of experimental techniques have been used, both for volumetric and interfacial characterization. Among them, the implementation of the Electrooptical Kerr Effect technique developed during the course of this thesis stands out. Firstly, a system composed of anionic polyelectrolytes and an anticancer drug, Doxorubicin hydrochloride, will be used to determine local dielectric properties in poly- electrolyte multilayer systems. Then, two pH-responsive systems will be presented. The first one, a mixture of polyacrylic acid (PAA) and a non-commercial cationic surfactant Gemini 12-2-12, will be characterized in surface and volume, showing that polymer- surfactant interactions dominate and determine the aggregate structure. They can be modulated by pH in order to obtain a stimuli-responsive system. The second one, com- posed of polyallylamine hydrocholoride (PAH) and several polyphosphate salts; through morphological and thermodynamic characterizations it will be shown and explained that the amount of phosphate groups is determinant in the responsivity; obtaining nanopar- ticles with different ranges of stability against pH. Finally, As a model system for gene therapies, results of a mixed system of deoxyribonucleic acid (DNA) with a cationic surfactant such as dodecyltrimethylammonium bromide (DTAB) will be shown. The assembly process and the interactions involved, together with morphological variations will be followed by electro-optical Kerr effect.