Porcine Reproductive and Respiratory Syndrome (PRRS) Authors: Jeff Zimmerman, Iowa State University; David Benfield, The Ohio State University; Jane Christopher-Hennings, South Dakota State University; Scott Dee, University of Minnesota; Greg Stevenson, Purdue University.
Therefore, the substance zirconia aluminosilicate refractory ceramic fibres (SiO 2, Al 2 O 3, ZrO 2) as described in this document are a subset of the group of substances which are defined by the refractory ceramic fibres in Annex VI of the Regulation (EC) No 1272/2008.
For other uses, see Silica (disambiguation) . The chemical compound silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with a chemical formula of Template:SiliconTemplate:Oxygen and has been known for its hardness since antiquity.Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms.n dimeric silicon dioxide there are two oxygen atoms bridging between the silicon atoms with an Si-O-Si angle of 94Â° and bond length of 164.6 pm and the terminal Si-O bond length is 150.2 pm. The Si-O bond length is 148.3 pm which compares with the length of 161 pm in Î±-quartz.