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Protactinium-231 is the longest-lived isotope of protactinium, with a half-life of 32,760 years. In nature, it is found in trace amounts as part of the actinium series, which starts with the primordial isotope uranium-235; the equilibrium concentration in uranium ore is 46.55 231 Pa per million 235 U.
The longest-lived and most abundant (nearly 100%) naturally occurring isotope of protactinium, protactinium-231, has a half-life of 32,760 years and is a decay product of uranium-235. Much smaller trace amounts of the short-lived protactinium-234 and its nuclear isomer protactinium-234m occur in the decay chain of uranium-238 .
Protactinium(V) fluoride can be prepared by reacting protactinium oxide with either bromine pentafluoride or bromine trifluoride at about 600 °C, and protactinium(IV) fluoride is obtained from the oxide and a mixture of hydrogen and hydrogen fluoride at 600 °C; a large excess of hydrogen is required to remove atmospheric oxygen leaks into the ...
The largest component is the remaining uranium which is around 98.25% uranium-238, 1.1% uranium-235, and 0.65% uranium-236. The U-236 comes from the non-fission capture reaction where U-235 absorbs a neutron but releases only a high energy gamma ray instead of undergoing fission.
As protactinium(V) oxide, like other protactinium compounds, is radioactive, toxic and very rare, it has very limited technological use. Mixed oxides of Nb, Mg, Ga and Mn, doped with 0.005–0.52% Pa 2 O 5 , have been used as high temperature dielectrics (up to 1300 °C) for ceramic capacitors .
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Privately owned public spaces (POPS) in New York City were introduced in the 1961 Zoning Resolution. The city offers zoning concessions to commercial and residential developers in exchange for a variety of spaces accessible and usable for the public. There are over 590 POPS at over 380 buildings in New York City and are found principally in Manhattan. Spaces range from extended sidewalks to ...
Protactinium(IV) chloride is a chartreuse, hygroscopic, crystalline solid that can be sublimed at 400 °C in a vacuum. It is soluble in strong mineral acids , forming green solutions. The complex PaCl 4 ·4CH 3 CN is formed with acetonitrile .