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Sunglasses allow better vision in bright daylight, and may protect one's eyes against damage from high levels of ultraviolet light. Typical sunglasses are darkened for protection against bright light or glare; some specialized glasses are clear in dark or indoor conditions, but turn into sunglasses when in bright light. Most sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be ordered. Specialized glasses may be used for viewing specific visual information (such as stereoscopy) or 3D glasses for viewing three-dimensional movies. Sometimes glasses with no corrective power in the lenses are worn simply for aesthetic or fashion purposes. Even with glasses used for vision correction, a wide range of designs are available for fashion purposes, using plastic, wire, and other materials.
Some algae species are 50% or maybe more lipid oil by weight. This oil can be pressed in the algae and refined into diesel. The process for extracting algal oil, at its most elementary level, is similar to pressing an olive. Up to 75% with the oil could be squeezed from algae which has a simple mechanical press. Hexane may be used as a solvent to increase extraction as much as 95%. Once extracted, the oil is refined through transesterification. A catalyst including sodium hydroxide is when combined alcohol to create biodiesel and glycerol.
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