Young basalts from Kilauea Volcano, Hawai'i, frequently feature opaque surface coatings, 1–80 μm thick, composed of amorphous silica and Fe-Ti oxides. These coatings are the product of interaction of the basaltic surface with volcanically-derived acidic fluids. Previous workers have identified these coatings in a variety of contexts on Hawai'i, but the timescales of coating development, coating...

BACKGROUND South Africa is the largest producer of platinum group metals in the world. Platinum is found in the Bushveld Complex in the north-east of the country. This volcanic intrusion contains many other minerals, including crystalline silica. Little is known about the health risks in the platinum mining industry. AIMS To explore the potential for platinum mine workers to develop silicosis...

Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transfor...

We present the modelling of stimulated Brillouin scattering (SBS) in graded index polymer fibres made with fluoropolymer CYTOPr(Cyclic Transparent Optical Polymer). Comparison of SBS in silica and polymer optical fibres is presented. What emerges is that polymer-based fibre sensors require, compared to silica-fibres sensors, higher power sources (in the order of Watts). The innovative aspect of...

Fused silica fibers with a dumbbell-shaped diameter profile are proposed to simultaneously achieve low thermal noise and low vertical bounce frequency in an interferometric gravitational wave detector. We present a theoretical analysis of achievable noise spectra. We also survey the sources of dissipation in fused silica fibers. Finally, we apply the model to analyze the influence of welded end...

A diffraction grating engraved on a two-dimensional photonic crystal composed of square air holes in a silica matrix is numerically studied for the compression of ultrashort pulses. The silica is therefore the only solid material of the grating, and the reflection of the incident beam is based on the contrast of the air and silica refractive indices. This optical component enables the single us...

The particle growth of silica below the isoelectric point plays a key role in oil well cements, production of silica gels and production of nanosilica by dissolving silicates. In this article, we study the particle growth of silica below the isoelectric point using olivine, a silicate mineral, and sodium silicate solutions as silica sources in acid, where the particle size, soluble silica conce...

Pesticides are widely used in agriculture, although they may create hazards both to humans and to the environment. In order to reduce the harmful effects of their administration, there has been made a great effort to find solutions. The porous sol-gel silica materials which are able to entrap different organic molecules represent new studied controlled release carriers. The aim of the present w...