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There are seven stable isotopes of mercury (80 Hg) with 202 Hg being the most abundant (29.86%). The longest-lived radioisotopes are 194 Hg with a half-life of 444 years, and 203 Hg with a half-life of 46.612 days.
A welding helmet in use. A welding helmet is a piece of personal protective equipment used by welders to protect the user from concentrated light and flying particles. . Different welding processes need stronger lens shades with auto-darkening filters, while goggles suffice for
For an ND filter with optical density d, the fraction of the optical power transmitted through the filter can be calculated as =, where I is the intensity after the filter, and I 0 is the incident intensity. [1]
The California Job Case was a compartmentalized box for printing in the 19th century, sizes corresponding to the commonality of letters. The frequency of letters in text has been studied for use in cryptanalysis, and frequency analysis in particular, dating back to the Arab mathematician al-Kindi (c. AD 801–873 ), who formally developed the method (the ciphers breakable by this technique go ...
Typically the transfer stage is filled directly and no depot is included in the architecture. For cryogenic vehicles and cryogenic depots, additional boiloff mitigation equipment is typically included on the transfer stage, reducing payload fraction and requiring more propellant for the same payload unless the mitigation hardware is expended.
The deserts of Australia or the Australian deserts cover about 1,371,000 km 2 (529,000 sq mi), or 18% of the Australian mainland, but about 35% of the Australian continent receives so little rain, it is practically desert. [1]