Pyrolysis oil are affected by temperature, reaction time, algae species, algae concentration, reaction atmosphere, and catalysts, in subcritical water reaction conditions. Bio-oil typically requires significant additional treatment to render it suitable as a refinery feedstock to replace crude oil derived from petroleum, coal-oil, or coal-tar. Tar is a black mixture of hydrocarbons and free carbon obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat. Wood-tar creosote is a colourless to yellowish greasy liquid with a smoky odor, produces a sooty flame when burned, and has a burned taste. It is
English words of Greek origin "bacterium" < βακτήριον 'stick (diminutive)' is a kind of microorganism rather than a small stick or staff. This also applies to combining forms used in neologisms: "-cyte" or "cyto-" < κύτος 'container' means biological cells, not arbitrary containers; "-oma" < -ωμα, a generic morpheme forming deverbal nouns such as "diploma" 'a folded thing' and "glaucoma" 'greyness', comes to have the very narrow meaning of 'tumor' or 'swelling', on the model of words like "carcinoma" < καρκίνωμα. For example, "melanoma" does not come from Greek μελάνωμα 'blackness', but rather from the modern combining forms "melano-" 'dark (in biology)' + "-oma" 'tumor'.