Fluorinated gases pharmaceutical industries, as well as in refrigeration when combined with other gases. PFCs were commonly used as fire extinguishants in the past and are still found in older fire protection systems. They are also a by-product of the aluminium smelting process. Sulphur hexafluoride (SF) is used primarily as an insulation gas. It can be found in high-voltage switchgear and is used in the production of magnesium. HFCs were developed in the 1990s to substitute substances such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). As these substances were found to deplete the ozone layer, the Montreal Protocol lays down provisions for them
Full-service community schools in the United States magnet schools, and alternative schools, the full-service community school model is one of many educational reform efforts that are intended to increase student achievement, but the full-service community school model specifically focuses on the development of the community as a whole. A charter school receives public funds but is not subject to all of the rules, regulations, and statutes public schools must adhere to. A charter school is accountable to what is sent forth in its individual charter. A school voucher is a certificate issued by the government to allow families to apply it the cover the tuition at a