Ozone vacuum-ultraviolet (VUV) ozone generators, employ a light source that generates a narrow-band ultraviolet light, a subset of that produced by the Sun. The Sun's UV sustains the ozone layer in the stratosphere of Earth. UV ozone generators use ambient air for ozone production, no air prep systems are used (air dryer or oxygen concentrator), therefore these generators tend to be less expensive. However UV ozone generators usually produce ozone with a concentration of about 0.5% or lower which limits the potential ozone production rate. Another disadvantage of this method is that it requires the ambient air (oxygen) to be exposed
The City of the Sun to observe the stars and, using astronomical instruments, to take account of all their movements. It is their job to indicate the times most favorable for generation and for agricultural labors, acting in this way as intermediaries between God and human beings. In Trento's Civic Library, there is kept a 1602 manuscript of "The City of the Sun" (shelf mark BCT1-1538), discovered in 1943 by Italian historian Luigi Firpo. It is considered the most ancient manuscript copy that has survived to present time. The text arrived at the Library through the baron Antonio Mazzetti 's (1781–1841) bequest. He was a