Patents. A process for preparing low molecular weight, highly reactive polyisobutylene having an average molecular weight Mn of from 500 to 5000 Dalton and a terminal double bond content of more than 80 mol % by polymerization in the liquid phase of isobutene or hydrocarbon streams comprising isobutane [sic]...ccording to stage (c) the enriched and/or separated catalyst complex is then recycled, usually without further purification, to the polymerization, in the case of a multi-stage polymerization generally into the first stage. It is generally possible to recycle from 70 to 90% of the catalyst complex.
A vascular birthmark is a discoloration of the skin that is caused by blood vessels that don't form correctly. They are present at birth or appear shortly after birth. There are three major types of vascular birthmarks: Salmon patch (nevus simplex) is a flat patch of pink or red skin, often small, usually with poorly defined borders.
Cafe-au-lait spots may be a normal type of birthmark, but the presence of several cafe-au-lait spots larger than a quarter may occur in neurofibromatosis (a genetic disorder that causes abnormal cell growth of nerve tissues).