A new inexpensive method for the preparation of acicular precursors for magnetic recording media

Magnetic materials meant for audio/video recording applications necessitate that polycrystalline materials be in acicular shape. So preparation of acicular precursors for magnetic storage materials assumes significance. The employment of aqueous solutions do not produce needle shape crystallites. Glycerol is one of the complexing media used for the precipitation of ferrous oxalate dihydrate. An inexpensive method using starch for preparation of acicular particles is described. The influence of an additive namely Gd on acicularity is also investigated

Silver-doped photopolymer media for holographic recording

Incorporation of silver ions into a dye-sensitized poly(vinyl alcohol)/acrylamide photopolymer is observed to give better performance compared to other metal-ion-doped photopolymer holographic recording media. Plane-wave transmission gratings were recorded in the photopolymer films using a He–Ne laser, and various holographic parameters were optimized so as to explore maximum potential of the material for various holographic applications. Silver-doped films showed good energy sensitivity, and gratings recorded in optimized film exhibited a diffraction efficiency of more than 75%. The potential of the material for holographic data storage applications is also studied using peristrophic multiplexing

Catalysis by Modified Pillared Clays and Porous Clay Heterostructures

In this venture three distinct class of catalysts such as, pillared clays and transition metal loaded pillared clays , porous clay heterostructures and their transition metal loaded analogues and DTP supported on porous clay heterostructures etc. were prepared and characterized by various physico chemical methods. The catalytic activities of prepared catalysts were comparatively evaluated for the industrially important alkylation, acetalization and oxidation reactions.The general conclusions drawn from the present investigation are  Zirconium, iron - aluminium pillared clays were synthesized by ion exchange method and zirconium-silicon porous heterostructures were Summary and conclusions 259 prepared by intergallery template method. Transition metals were loaded in PILCs and PCHs by wet impregnation method.  Textural and acidic properties of the clays were modified by pillaring and post pillaring modifications.  The shift in 2θ value to lower range and increase in d (001) spacing indicate the success of pillaring process.  Surface area, pore volume, average pore size etc. increased dramatically as a result of pillaring process.  Porous clay heterostructures have higher surface area, pore volume, average pore diameter and narrow pore size distribution than that of pillared clays.  The IR spectrum of PILCs and PCHs are in accordance with literature without much variation compared to parent montmorillonite which indicate that basic clay structure is retained even after modification.  The silicon NMR of PCHs materials have intense peaks corresponding to Q4 environment which indicate that mesoporous silica is incorporated between clay layers.  Thermo gravimetric analysis showed that thermal stability is improved after the pillaring process. PCH materials have higher thermal stability than PILCs.  In metal loaded pillared clays, up to 5% metal species were uniformly dispersed (with the exception of Ni) as evident from XRD and TPR analysis. Chapter 9 260  Impregnation of transition metals in PILCs and PCHs enhanced acidity of catalysts as evident from TPD of ammonia and cumene cracking reactions.  For porous clay heterostructures the acidic sites have major contribution from weak and medium acid sites which can be related to the Bronsted sites as evident from TPD of ammonia.  Pillared clays got more Lewis acidity than PCHs as inferred from α- methyl styrene selectivity in cumene cracking reaction.  SEM images show that layer structure is preserved even after modification. Worm hole like morphology is observed in TEM image of PCHs materials  In ZrSiPCHS, Zr exists as Zr 4+ and is incorporated to silica pillars in the intergallary of clay layers as evident from XPS analysis.  In copper loaded zirconium pillared clays, copper exists as isolated species with +2 oxidation state at lower loading. At higher loading, Cu exists as clusters as evident from reduction peak at higher temperatures in TPR.  In vanadium incorporated PILCs and PCHs, vanadium exist as isolated V5+ in tetrahedral coordination which is confirmed from TPR and UVVis DRS analysis.  In cobalt loaded PCHs, cobalt exists as CoO with 2+ oxidation state as confirmed from XPS.  Cerium incorporated iron aluminium pillared clay was found to be the best catalyst for the hydroxylation of phenol in aqueous media due to the additional surface area provided by ceria mesopores and its redox properties. Summary and conclusions 261  Cobalt loaded zirconium porous clay heterostructures were found to be promising catalyst for the tertiary butylation of phenol due to higher surface area and acidic properties.  Copper loaded pillared clays were found to be good catalyst for the direct hydroxylation of benzene to phenol.  Vanadium loaded PCHs catalysts were found to be efficient catalysts for oxidation of benzyl alcohol.  DTP was firmly fixed on the mesoporous channels of PCHs by Direct method and functionalization method.  DTP supported PCHs catalyst were found to be good catalyst for acetalization of cyclohexanone with more than 90% conversion.

Analytical Study of Light Propagation in Highly Nonlinear Media

The present dissertation is devoted to the construction of exact and approximate analytical solutions of the problem of light propagation in highly nonlinear media. It is demonstrated that for many experimental conditions, the problem can be studied under the geometrical optics approximation with a sufficient accuracy. Based on the renormalization group symmetry analysis, exact analytical solutions of the eikonal equations with a higher order refractive index are constructed. A new analytical approach to the construction of approximate solutions is suggested. Based on it, approximate solutions for various boundary conditions, nonlinear refractive indices and dimensions are constructed. Exact analytical expressions for the nonlinear self-focusing positions are deduced. On the basis of the obtained solutions a general rule for the single filament intensity is derived; it is demonstrated that the scaling law (the functional dependence of the self-focusing position on the peak beam intensity) is defined by a form of the nonlinear refractive index but not the beam shape at the boundary. Comparisons of the obtained solutions with results of experiments and numerical simulations are discussed.

The Media is the Message?!

Diese Arbeit beschäftigt sich mit der grafischen Gestaltung von Mathematiklehrwerken und der damit verbundenen Wirkungen auf die SchülerInnen. Es wurde untersucht, welche Art von Gestaltungsaspekten in Schulbüchern eine positive Auswirkung auf die Lernmotivation hat. Im theoretischen Teil dieser Arbeit wird zunächst erläutert, wie der menschliche Wahrnehmungsapparat nach theoretischen Erkenntnissen aus der Wahrnehmungspsychologie visuelle Elemente wie Farbe und Form verarbeitet. Anhand gestaltpsychologischer und motivationspsychologischer Theorien werden mögliche Einflüsse und in diesem Zusammenhang bedeutungsvolle Aspekte aufgezeigt. Einzelne Funktionen und Wirkungsaspekte der einzelnen Medienbausteine wie Bild, Typografie und Bild-Text-Kombinationen werden anhand von Beispielen aus Mathematiklehrwerken dargestellt. Ein Exkurs über den vermehrten Einfluss der neuen Medien bei Kindern und Jugendlichen verdeutlicht, welche visuellen Medienerfahrungen Kinder und Jugendliche bei der Betrachtung eines Schulbuches mitbringen. Anschließend werden die erarbeiteten theoretischen Grundlagen in einer praktischen Arbeit genutzt. Eine exemplarisch ausgewählte Seite eines Mathematiklehrwerks werde unter verschiedenen gestalterischen Gesichtspunkten umgestaltet, so dass mehreren Varianten entstehen. Diese Entwürfe werden in einer qualitativen Studie mit einzelnen SchülerInnen diskutiert. Die Ergebnisse der aufgezeichneten Interviews wurden durch die Auswertungsmethode des zirkulären Dekonstruierens auf die aufgeworfenen Forschungsfragen untersucht und ausgewertet.

Detecting ultrafast interatomic electronic processes in media by fluorescence

Interatomic coulombic decay (ICD), a radiationless transition in weakly bonded systems, such as solutes or van der Waals bound aggregates, is an effective source for electrons of low kinetic energy. So far, the ICD processes could only be probed in ultra-high vacuum by using electron and/or ion spectroscopy. Here we show that resonant ICD processes can also be detected by measuring the subsequently emitted characteristic fluorescence radiation, which makes their study in dense media possible.

Informe sobre detección de necesidades de formación : zona formativa 3 : Vegas Alta y Media, Comarca Oriental y Valle de Ricote.

Resultados del trabajo realizado por la Comisión Territorial de Formación Profesional en el que se detectan las necesidades formativas en los municipios de la comarca de la Vega Alta y Media; Oriental, y Valle de Ricote pertenecientes a la Región de Murcia; zona de influencia de esta Comisión. El objetivo de este trabajo es dar respuesta a la demanda de recursos humanos por parte del sistema productivo, porporcionando al sistema formativo las bases para redefinir y actualizar de forma constante tanto el conjunto de perfiles profesionales presentes como los que se puedan detectar en el futuro. En este informe se estudia la situación de cuatro escenarios relevantes: población, mercado laboral, sistema productivo y oferta formativa. Para ello se han analizado las siguientes fuentes de información: matriz DAFO; encuesta realizada por el Observatorio Regional de Empleo sobre necesidades formativas y ocupacionales; análisis de las principales variables socioeconómicas de la zona formativa y, por último el estudio de la oferta formativa, tanto de formación profesional reglada, como ocupacional.

Edad Media en Asturias : materiales para el aula.

Presentar un material que puede experimentarse en el ciclo entre 12 y 16 años, sobre la Edad Media en Asturias: formación de polas, con el fin de que el profesor al tratar el tema los sintetice y simplifique al máximo. La formación de polas y el comercio de la sal como eje de las relaciones económicas en Asturias destacando unos contenidos que permiten analizar la evolución desde una sociedad autosuficiente a una mercantilista, desde una sociedad de esclavos a una de hombres libres. El dossier posee una estructura de 5 unidades en las que aparecen varios núcleos temáticos (bases de la Economía asturiana en la Edad Media; la estructura social: monarquía; nobleza, Iglesia, clases populares; el comercio de la sal; los asentamientos urbanos medievales: las polas; el Románico como expresión artística de la época) en los que se exponen primero los contenidos luego una serie de actividades a desarrollar por los niños, contiene, además, esquemas, textos, preguntas sobre los textos, mapas y dibujos, un glosario de vocablos y su significado y una cronología general y una de la época de la monarquía Asturiana. Finalmente divide la bibliografía en una bibliografía fundamental y otra de ampliación. El proyecto Edad Media en Asturias: formación de polas es un material adaptable a un 'currículo abierto' posee un desarrollo en espiral, a la vez que son fáciles de reconocer las unidades que permiten la experimentación directa. El dossier ofrece un planteamiento sencillo que permite el trabajo de los distintos núcleos: las bases económicas y la estructura social, como marco general para poder explicarse posteriormente; la unidad ejemplificadora, el comercio de la sal; un tema relevante, la formación de polas, con el deseo expreso de que sea tratado como trabajo monográfico. Los principios pedagógicos que orientaron las actividades son las propuestas del raths (reproducidos por Gimeno Sacristán): la pedagogía por objetivos: obsesión por la eficacia, por Stenhouse, L.: investigación y desarrollo del currículo.