Search results for "SIO2"
showing 10 items of 43 documents
Luminescence properties of chlorine molecules in glassy SiO 2 and optical fibre waveguides
2017
The support from Latvian Research Program IMIS 2, project “Photonics and materials for photonics” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Materials and Structures Laboratory, Tokyo Institute of Technology. The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.
Electroluminescence and transport properties in amorphous silicon nanostructures
2006
We report the results of a detailed study on the structural, electrical and optical properties of light emitting devices based on amorphous Si nanostructures. Amorphous nanostructures may constitute an interesting system for the monolithic integration of optical and electrical functions in Si ULSI technology. In fact, they exhibit an intense room temperature electroluminescence (EL), with the advantage of being formed at a temperature of 900 °C, while at least 1100 °C is needed for the formation of Si nanocrystals. Optical and electrical properties of amorphous Si nanocluster devices have been studied in the temperature range between 30 and 300 K. The EL is seen to have a bell-shaped trend …
Metal-support and preparation influence on the structural and electronic properties of gold catalysts
2006
Abstract Nanostructured gold catalysts supported on CeO2 and SiO2 were prepared by the deposition–precipitation (DP) and the solvated metal atom dispersion (SMAD) techniques. The structural and electronic properties of the catalysts were investigated by X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). Gold was found as small metal nanoparticles (cluster size ∼2 nm) in the SMAD-prepared samples and in ionic state in the DP catalysts. The catalytic activity of the samples was tested in the reaction of low temperature CO oxidation. Gold nanosized particles in a pure metallic state exhibited a worse catalytic performance, both on ceria and…
Inorganic Nanoparticle as a Carrier for Hepatitis B Viral Capsids
2011
Virus like particles (VLP) are used to transport immune response-modulating agents to target cells to treat them. In order to deliver a high concentration of VLP to the cell, a number of VLP can be attached to a nanoparticle to be used as a nanolorry. In this study, SiO2 nanoparticles were attached to Hepatitis B VLP. Spectrophotometry measurements, electron, and fluorescent microscopy evidence showed that the SiO2 – Hepatitis B VLP complexes were formed.
Structural relaxation of E_gamma centers in amorphous silica
2002
We report experimental evidence of the existence of two variants of the E' gamma centers induced in silica by gamma rays at room temperature. The two variants are distinguishable by the fine features of their line shapes in paramagnetic resonance spectra. These features suggest that the two E' gamma differ for their topology. We find a thermally induced interconversion between the centers with an activation energy of about 34 meV. Hints are also found for the existence of a structural configuration of minimum energy and of a metastable state.
Environment assisted photoconversion of luminescent surface defects in SiO 2 nanoparticles
2017
Abstract Time-resolved photoluminescence investigation on SiO 2 nanoparticles was carried out in controlled atmosphere, with the aim to discern the effects induced on the typical blue luminescence band by high power UV Nd:YAG laser photons (4.66 eV) and by some selected molecular species of the air (O 2 , N 2 , CO 2 , H 2 O). These factors ultimately determine both the brightness and photostability of the emitting defect, so as to limit the unique and attracting potentialities offered by this system in many applicative fields. Here it is highlighted that the effects due to photons and molecules, singularly considered, are not additive, the radiation being more dramatic in reducing the emiss…
Luminescence of gamma-radiation-induced defects in alpha-quartz
2004
Optical transitions associated with gamma-radiation-induced defects in crystalline a-quartz were investigated by photoluminescence excited by both pulsed synchrotron radiation and steady-state light. After a 10 MGy gamma-dose we observed two emissions at 4.9 eV (ultraviolet band) and 2.7 eV (blue band) excitable in the range of the induced absorption band at 7.6 eV. These two luminescence bands show a different temperature dependence: the ultraviolet band becomes bright below 80 K; the blue band increases below 180 K, but drops down below 80 K. Both emissions decay in a timescale of a few ns under pulsed excitation, however the blue band could also be observed in slow recombination processe…
Combined Effects of 50 Hz Electromagnetic Field and SiO2 Nanoparticles on Oxidative Stress in Plant’s Gametic Cells / Zemfrekvences (50 Hz) Elekromag…
2015
Abstract The paper presents the results of combined effects of an extremely low frequency electromagnetic field (50 Hz) (ELF EMF) and SiO2 nanoparticles on fluorescence of plant gametic cells (immature microspores). The data were recorded by a BD FACSJazz® cell sorter after cell irradiation by blue laser (488 nm). A significant difference of fluorescence was observed between gametic cells after 1 hour incubation in suspension of SiO2 nanoparticles and the control gametic cells. It was observed that fluorescence intensity of gametic cell was higher with ELF EMF treatment in comparison to control cells, but it was statistically significant only for cells treated with electromagnetic radiation…
Photocatalytic activity of TiO2/SiO2 systems
2009
Silica-supported TiO(2) powders were synthesized by a wet method under mild conditions. The aim of the work was the preparation of TiO(2)/SiO(2) additives for photocatalytic cements. Three types of commercial SiO(2) were used as supports: Cabot, Axim and Fly Ash. Cabot silica was ultra-pure whereas the other two silica contained different percentages of various oxides. The TiO(2)/SiO(2) samples, denoted TiO(2)/Cabot, TiO(2)/Axim and TiO(2)/Fly Ash, were prepared by boiling suspensions obtained by addition of silica to a solution of TiCl(4) in water (volume ratio 1:10). The photocatalytic activity was evaluated in a gas-solid system both in batch and in continuous reactors using 2-propanol a…
Electrical characterization of deoxyribonucleic acid hybridization in metal-oxide-semiconductor-like structures
2012
In this work, metal-oxide-semiconductor (MOS)-like sensors in which deoxyribonucleic acid (DNA) strands are covalently immobilized either on Si oxide or on a gold surface were electrically characterized. Si oxide fabrication process allowed us to have a surface insensitive to the solution pH. A significant shift in the flat band voltage was measured after single strand DNA immobilization (+0.47 +/- 0.04 V) and after the complementary strand binding (+0.07 +/- 0.02 V). The results show that DNA sensing can be performed using a MOS structure which can be easily integrated in a more complex design, thus avoiding the problems related to the integration of micro-electrochemical cells.