Tritium applications

Laser-Assisted Thermonuclear Fusion. An application with great potential importance, but which will not reach complete fmition for many years, is laser-assisted thermonuclear fusion (117) (see Fusion energy). The concept iavolves focusiag a high power laser beam onto a mixture of deuterium [7782-39-0] and tritium [10028-17-8] gases. The mixture is heated to a temperature around 10 K (10 keV) (see Deuterium AMD tritium). At this temperature the thermonuclear fusion reaction... 

Decay products of the principal radionuclides used in tracer technology (see Table 1) are not themselves radioactive. Therefore, the primary decomposition events of isotopes in molecules labeled with only one radionuclide / molecule result in unlabeled impurities at a rate proportional to the half-life of the isotope. Eor and H, impurities arising from the decay process are in relatively small amounts. Eor the shorter half-life isotopes the relative amounts of these impurities caused by primary decomposition are larger, but usually not problematic because they are not radioactive and do not interfere with the application of the tracer compounds. Eor multilabeled tritiated compounds the rate of accumulation of labeled impurities owing to tritium decay can be significant. This increases with the number of radioactive atoms per molecule. 

T. Yamanishi and co-workers, Nippon Genshiryoku Eenkyusho, (1988) R. H. Sherman, "Fusion Technology," S econd National Topical Meeting on Tritium in Fission, Fusion, and Isotopic Applications, Apr. —May, 1985, Dayton, Ohio. 

V. Malka, H.D. Rohrig, and R. Hecker. In Tritium Technology in Fission, Fusion, and Isotope Application, Proc. Conf., Dayton, OH (1980). 

A special type of substituent effect which has proved veiy valuable in the study of reaction mechanisms is the replacement of an atom by one of its isotopes. Isotopic substitution most often involves replacing protium by deuterium (or tritium) but is applicable to nuclei other than hydrogen. The quantitative differences are largest, however, for hydrogen, because its isotopes have the largest relative mass differences. Isotopic substitution usually has no effect on the qualitative chemical reactivity of the substrate, but often has an easily measured effect on the rate at which reaction occurs. Let us consider how this modification of the rate arises. Initially, the discussion will concern primary kinetic isotope effects, those in which a bond to the isotopically substituted atom is broken in the rate-determining step. We will use C—H bonds as the specific topic of discussion, but the same concepts apply for other elements. 

It is hoped that these volumes will be useful not only to the chemist who wishes to carry out synthesis in the steroid field, but also to the broader group of organic chemists who are interested in carrying out selective and stereo-chemically defined reactions, as well as protective chemistry on extraneous functional groups, during a broad range of synthetic applications. The chapter on the introduction of deuterium and by inference tritium into steroids was included because of the importance of this technique in mechanistic and metabolic studies both in the steroid and nonsteroid field. 

Evans, EA, DC Warrell, JA Elvidge and JR Jones, Handbook of Tritium NMR-Spectroscopy and Applications, New York, John Wiley and Sons, 1985. 

For special applications such as operation in strong magnetic fields, radiation hazard areas or in a tritium atmosphere, please contact our Technical Sates Department which has the necessary experience and which is available te you at any time. 

This chapter reviews the year s published work on physical and analytical aspects of steroid chemistry. No attempt has been made to survey the enormous number of routine applications of spectroscopic methods to structure determination. Attention has been concentrated mainly upon those developments of a fundamental nature which increase our understanding of the physical techniques and the phenomena which they explore. The major advances reported this year in the area of spectroscopy lie in the interpretation and applications of Cn.m.r. tritium n.m.r. has made its appearance as a method for the analysis of labelled steroids. The short sections on analytical methods give the Reviewer s selection of significant advances in radioimmunoassay and chromatographic methods of interest to chemists. 

A new detergent, Triton-101, in association with p-xylene is used for the suspension of 10 ml. of water with a Y value of approximately 0.5 nCi/liter. The application of a new instrumental technique with three photomultipliers decreases further the Y value of both mixtures. A Teflon cylinder with a volume of 250-300 ml. is used as sample container for low level counting with a Y value of approximately 0.2 nCi/liter. Selected results of samples collected during 1967 are reported, and the radiation dose to the population of the United States from tritium is estimated to be approximately 0.2 mrem./year. 

The radionuclides commercially available and most commonly used for a number of the foregoing applications include anhmony-125 banum-133, 207 bismuth-207 bromine-82 cadmium-109, 115 m calcium-45 carbon-14 cerium-141 cesium-134, 137 chlorine-36 chromium-51 cobalt-57, 58, 60 copper-64 gadolimum-153 germanium-68 gold-195. 198 hydrogen-3 (tritium) indium-111, 114 m iodine-125, 129, 131 iron-55, 59 krypton-85 manganese-54 mercury-203 molvbdenum-99 nickel-63 phosphorus-32. 33 potassium-42 promethium-147 rubidium-86 ruthenium-103 samarium-151 scandium-46 selenium-75 silver-110 m sodium-22, strontium-85 sulfur-35 technetium-99 thallium-204 thulium-171 tin-113, 119 m, 121 m. titamum-44 ytterbium-169, and zinc-65. 

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