In simple words, an Oxygen Concentrator works on electricity; takes in room air, removes Nitrogen from it and provides upto 95% pure Oxygen. The composition of air (78% Nitrogen, 21% Oxygen and 1% other gases like Carbon Dioxide, Argon, etc.) clearly shows that air is mainly comprised of two gases: Nitrogen and Oxygen [together 99%].
Word Origin and History for savoir-faire Expand. n. instinctive knowledge of the right course of action in any circumstance, 1815, from French, literally to know (how) to do, from savoir to know (from Latin sapere; see sapient) + faire (from Latin facere; see factitious).
Ultra vires is a legal doctrine that states any act a business entity takes that is outside the scope of its business purpose is invalid. Under this doctrine, for example, an LLC could be sued for acts it took outside the scope of what its stated business purpose was.