No abstract

Transparent silica gel–polymer composites have been prepared by the impregnation of porous gels with organic monomer and polymerization in situ. The relative amount of each phase was adjusted by varying the porosity of the silica gel prior to impregnation. These materials constitute a new class of transparent composites. Properties, such as density, refractive index, modulus of rupture, compressive strength, abrasion rate, and Vickers hardness, have been measured over the compositional range of 100% silica to 100% polymethyl methacrylate (PMMA).

Abstract. The primary objective of this work is to evaluate the potential of silica gel encapsulated pancreatic islets of Langerhans, or islet tissue, as a means by which insulin secretory capacity might be restored to individuals with insulin dependent, type 1, diabetes mellitus. The encapsulation material under investigation is comprised of sol-gel derived silica ceramic that hardens under conditions of pH, salinity, and temperature that are not harmful to living cells and organisms. Preliminary efficacy has been demonstrated by measurement of insulin secretory response of silica gel encapsulated pancreatic islets in vitro and blood sugar levels of nonobese diabetic mice in vivo.

Neodymia-doped glasses are currently commercially available for use in laser systems. 'Qpically, these glasses are low-softening-temperature borates, phosphates, silicates, and fluorides. With its high softening temperature, high thermal shock resistance, and low nonlinear index of refraction, silica may be an ideal candidate for a neodymia host glass for high-power laser applications. Conventional glass processing methods, however, have thus far succeeded in incorporating only low levels of neodymia in silica. In this paper, the fabrication of neodymia-silica glasses with high neodymia content by the sol-gel route is described. A possible structure for neodymia in silica is discussed.