In Japanese mythology, jikininki are the spirits of dead people whose greed prevented their souls from entering a more peaceful existence after death and who lead a half-life by eating corpses. Research Jikininki
Krypton, named from the Greek word kryptos, meaning 'hidden', is an odourless, colourless, tasteless, non-toxic, monatomic, and highly stable gaseous element of the noble gases group with the symbolKr. The concentration of Krypton gas in the atmosphere by volume is 1.1 x 10-4. Traces of krypton are present in minerals and meteorites, but the usual commercial source is the atmosphere, which contains 1.14 parts per 106 by volume. Krypton also is formed by the nuclear fission of uranium triggered by slow neutrons: this source may be expected to become increasingly important because of the growing number of fission-power plants.
Krypton has isotopes of every mass number from 74 through 95; six, with mass numbers 78, 80, 82, 83, 84, and 86, are stable. After it has been stored a few days, krypton obtained by nuclear fission contains only one radioactiveisotope, krypton-85, which has a half-life of about 10 years, because all the other radioactive isotopes have half-lives of three hours or less. Because its boiling point is about 30 degrees C higher than those of the major constituents of air,
krypton is readily separated from liquid air by fractional distillation; it accumulates along with xenon in the least volatile portion. These two gases are further purified by adsorption onto silicagel, redistillation, and passage over hot titanium metal, which removes all impurities except other noble gases.
Krypton gas liquefies at -152.30 degrees C and freezes 4 degrees C lower. When a current of electricity is passed through a glass tube containing krypton at low pressure, a bluish white light is emitted. The wavelength of an orange-red component of light emitted by stable
krypton-86, because of its extreme sharpness, served as the international standard for the metre from 1960 to 1983. (One metre equals 1,650,763.73 times the wavelength of this line).
Krypton gas is principally shipped and used in gaseous form for excimer lasers, light bulbs, window insulation and Research and Development laboratory research. Research Krypton
Plutonium is a radioactive metal element with the symbolPu. It was discovered by the chemists Glenn Seaborg and Edwin McMillan in 1940. The isotopes of plutonium were first prepared and studied by Seaborg and his associates in 1941. Trace amounts of the element have since been found in uranium ores, but plutonium is prepared in relatively large quantities today in nuclear reactors. Chemically, plutonium is reactive, its properties somewhat resembling those of the rare earth elements. The silvery metal, which becomes slightly yellow through oxidation caused by exposure to air, exists in six varying crystalline forms and has four different oxidation states. The metal gives off heat because of its radioactivity ; 15 different isotopes of
plutonium, ranging in mass number from 232 to 246, are known.
Plutonium-239 has a half-life of 24,360 years, and is produced by bombarding uranium-238 with slow neutrons. This forms neptunium-239, which in turn emits a beta particle and forms plutonium-239.
Plutonium is the most economically important of the transuranium elements because plutonium-239 readily undergoes fission and can be both used and produced in quantity in nuclear reactors. It is also used in making nuclear weapons. It is an extremely hazardous poison due to its high radioactivity. Plutonium-238 has been used to power equipment on the moon by means of the heat it emits. Research Plutonium
Xenon is a rare, gaseous element discovered in July 1898. It's symbol is Xe.
Xenon is a heavy (4.5 times heavier than air), unreactive stable gas occurring in air in trace percentages. It is one of the noble gases. Today, xenon is recovered on a commercial scale by the fractional distillation of liquid air. Natural xenon is a mixture of nine stable isotopes in the following percentages; xenon-124 (0.096); xenon-126 (0.090); xenon-128 (1.92); xenon-129 (26.44); xenon-130 (4.08); xenon-131 (21.18); xenon-132 (26.89) ; xenon-134 (10.44); and
xenon-136 (8.87).
The xenon found in some stony meteorites shows a large proportion of xenon-129, believed to be a product of radioactive decay of iodine-129, whose half-life is 17,000,000 years. Study of the xenon- 129 content of meteorites casts light on the history of the solar system. More than a dozen radioactive xenon isotopes produced by fission of uranium and other nuclear reactions are known. For example, xenon-135 (9.2-hour half-life) is produced by uraniumfission in nuclear reactors, where it is troublesome because it absorbs fission-producing neutrons. In 1962, a sample of xenon combined with an ion of platinum and fluorine to produce the first noble gas compound, previously the noble gases were thought to be inert. Now, xenon is known to combine with fluorine, oxygen, cesium, and alkali metals to form the corresponding fluorides, oxides and salts. All xenon compounds are toxic, although the gas itself is not.
Xenon has been used as an aesthetic, and is used as a tracer to measure lung capacity. It is the most popular gas used in strobe lamps and in high speed electronic flash bulbs used in photography. Electrical excitation of xenon atoms produces a brilliant white light. Some of its compounds have limited application as oxidizing agents. Xenon gas also has applications in modern nuclear power reactors. Research Xenon
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Jikininki
