Ex nihilo is a Latin phrase meaning out of nothing,â which often appears in conjunction with the concept of creation, as in creatio ex nihilo, meaning creation out of nothing.â Not only do scientists think the Universe was created out of nothing, or that nothing existed before the singularity, but even Creationists, those who believe God created ...
There are two main categories of diaphragm valves: one type seals over a weir (saddle) and the other (sometimes called a full bore or straight-way valve) seals over a seat.
Heart Anatomy The four cardiac valves are classified into two types - the atrioventricular [mitral and tricuspid] and the semilunar [aortic and pulmonic] valves. This is an important distinction. During systole, atrioventricular valves are closed and semilunar valves are open.