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Fugacity and BCF relate to each other in the following equation: = [6] where Z Fish is equal to the Fugacity capacity of a chemical in the fish, P Fish is equal to the density of the fish (mass/length 3), BCF is the partition coefficient between the fish and the water (length 3 /mass) and H is equal to the Henry's law constant (Length 2 /Time 2) [6]
Postal rates to 1847. Initial United States postage rates were set by Congress as part of the Postal Service Act signed into law by President George Washington on February 20, 1792. The postal rate varied according to "distance zone", the distance a letter was to be carried from the post office where it entered the mail to its final destination.
The 5-cent stamp paid for a letter weighing less than 1/2 ounce and traveling up to 300 miles, the 10-cent stamp for deliveries to locations greater than 300 miles, or, twice the weight deliverable for the 5-cent stamp. Each stamp was hand engraved in what is believed to be steel, and laid out in sheets of 200 stamps.
Grill (philately) "G" grill on a stamp of the 1869 issue. A grill on a postage stamp is an embossed pattern of small indentations intended to discourage postage stamp reuse. Used in the United States in the 1860s and 1870s, they were designed to allow the ink of the cancellation to be absorbed more readily by the fibres of the stamp paper ...
Scholars deciphered inscriptions on 4,000-year-old tablets more than 100 years after they were originally discovered. Omens on the tablet threaten tragedies including famines, plagues, and invasions.
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The bicentennial stamps were first placed on sale January 1, 1932, at the post office in Washington, D.C. While the bicentennial issue presents many unfamiliar images of Washington, the Post Office took care to place the widely loved Gilbert Stuart portrait of the president on the 2-cent stamp, which satisfied the normal first-class letter rate and would therefore get the most use.
Tris (pentafluorophenyl)borane, sometimes referred to as "BCF", is the chemical compound (C6F5)3B. It is a white, volatile solid. The molecule consists of three pentafluorophenyl groups attached in a "paddle-wheel" manner to a central boron atom; the BC3 core is planar. It has been described as the “ideal Lewis acid ” because of its high ...