Search results for "Structural modification"
showing 5 items of 5 documents
Structural Modification Processes in Bulk and Nano-sized Amorphous SiO2 Systems.
2011
Thermally Induced Structural Modification of Silica Nanoparticles Investigated by Raman and Infrared Absorption Spectroscopies
2010
We report an experimental investigation by Raman and infrared (IR) absorption spectroscopies on the structural modifications induced by isochronal thermal treatments on amorphous SiO2 nanoparticles (fumed silica). In particular, three different commercial types of this material, characterized by particle mean diameters of 7, 14, and 40 nm, were subjected to thermal treatments from 100 up to 1000 °C. We found that some properties of fumed silica, such as the SiOSi mean bond angle, ring size distribution, and surface adsorbed water content, are drastically different from those of common bulk silica materials and intimately related to the particles' dimension. The SiOSi mean bond angle, probed…
Photoluminescence of Point Defects in Silicon Dioxide by Femtosecond Laser Exposure
2021
The nature of the radiation-induced point defects in amorphous silica is investigated through online photoluminescence (PL) under high intensity ultrashort laser pulses. Using 1030 nm femtosecond laser pulses with a repetition rate of 1 kHz, it is possible to study the induced color centers through their PL signatures monitored during the laser exposure. Their generation is driven by the nonlinear absorption of the light related to the high pulse peak powers provided by femtosecond laser, allowing to probe the optical properties of the laser exposed region. The experiment is conducted as a function of the laser pulse power in samples with different OH contents. The results highlight the dif…
Alcoholic Parotid Sialosis: A Structural and Ultrastructural Study
2004
OBJETIVOS: El propósito del presente trabajo fue establecer posibles diferencias histopatológicas entre los estadíos iniciales y terminales de la sialosis alcohólica, patología que generalmente involucra hipertrofia parotídea y afecta estructuralmente en diverso grado a las demás glándulas salivales. DISEÑO DEL ESTUDIO: se analizaron y compararon las modificaciones estructurales y ultraestructurales de glándulas parótidas provenientes de: A) biopsias de alcohólicos crónicos con diagnóstico clínico de cirrosis hepática, de las que una fracción fue procesada para microscopía óptica (MO) y otra fracción fue fijada en glutaraldehído y procesada para microscopía electrónica de trasmisión (MET) J…
Dictamen profesional sobre la fusión y escisión como extrategias alternativas en un grupo de sociedades
2021
This work is a professional, legal opinion which sets out two alternative strategies (merger by absorption and partial demerger) in order to bring together the different areas of activity of the various companies in a group of companies. The aim is to provide solutions to the questions raised by customers and, therefore, to set out clearly and simply the procedure to be followed in each of the strategies, weighing up the advantages and disadvantages from each of them