Tritium solubility

Schroeder R. A., Setmire J. G., and Densmore J. N. (1991) Use of stable isotopes, tritium, soluble salts, and redox-sensitive elements to distinguish groundwater from irrigation water in the Salton Sea basin. In Irrigation and Drainage, Proc. 1991 national conference, Honolulu, Hawaii, July 22-26, 1991 (ed. W. F. Ritter). American Society of Civil Engineers. 

Neither tritium or deuterium gas, with zero dipole moments, can be expected to interact positively with microwave radiation. Their low solubilities are seen as a further disadvantage. Our thoughts therefore turned towards an alternative procedure, of using solid tritium donors and the one that has found most favor with us is formate, usually as the potassium, sodium or ammonium salt. Catalytic hydrogen transfer of this kind is remarkably efficient as the results for a-methylcinnamic acid show [50]. The thermal reaction, when performed at a temperature of 50 °C, takes over 2 h to come to equilibrium whereas the microwave-enhanced reaction is complete within 5 min. A further advantage is that more sterically hindered al-kenes such as a-phenylcinnamic acid which are reduced with extreme difficulty when using H2 gas and Wilkinson s catalyst are easily reduced under microwave-enhanced conditions. 

Measurement of the amount of tritium in the quenched samples was made by reheating them in a normal hydrogen ambient and measuring the evolved radioactivity. Since the samples contained tritium not only dissolved in the bulk crystal but also attached to the surface, mainly in a thin oxide film, measurements were made with and without removal of the latter by etching with HF, a procedure verified to remove the surface radioactivity. Their final results for the solubility s fell nicely on the Arrhenius line, ... 

The intracellular distribution of steroid hormone receptors has long been the object of controversy. The first theoretical formulation on the intracellular location of the ERs was elaborated by Jensen in 1968 and is known as the two-step theory. Its execution was based entirely on biochemical observations obtained by means of tritium-marked estradiol. The ERs, in cells not exposed to hormones, are found abundantly in the soluble cell fraction, or cytosol (Fig. 1.1). Treatment with hormones confines the receptors to the particulated or nuclear fraction and causes their disappearance from the cytosol. The two-step theory established that the receptor is found in the cytoplasm naturally and upon the arrival of a hormone it is transformed into a complex hormone-receptor (first step) capable of translocating itself to the nucleus and of modifying gene expression (second step). 

The conductivity changes accompanying and following the polymerisation of five portions of norbornadiene added to an aluminium bromide solution at -63 °C are shown in Figure 6 (Experiment No. R4). The polymer, which was precipitated during the reaction, was subsequently found to be insoluble and therefore presumably crosslinked. Since this polymer was, therefore, unsuitable for radiochemical assay, another experiment (RIO) was done with norbornadiene in a mixture of methyl and ethyl bromide at -125 °C to prevent cross-linking. The polymer was soluble and the number of tritium atoms per molecule of polymer was much greater than for polyisobutylene. 

A. cylindrica contains two soluble hydrogenases one of 100 kDa which exhibits MV-dependent H2 evolution and the other of 42 kDa which exhibits tritium exchange activity only. The MV-reactive enzyme is a heterodimer composed of a 50 kDa and the 42 kDa subunit form. Both proteins are required for MV reactivity (Ewart and Smith 1989). The function of this enzyme is unknown at present and the gene sequence for the tritium exchanging subunit is unrelated to any of the hydrogenases described above (Ewart et al. 1990). 

Ewart, G. D., Reed, K. C. and Smith, G. D. (1990) Soluble hydrogenase ol Anabaena cylin-drica. Cloning and sequencing of a potential gene encoding the tritium exchange subunit. Eur. J. Biochem., 187, 215-23. 

For general purpose tracer work, however, and particularly in polymer chemistry, the liquid scintillation counter surpasses all other instruments in its sensitivity and adaptability. There is no question on the author s mind that at the present time such an instrument would be the first choice, particularly where tritium, carbon-14 or sulphur-35 were involved. Samples for assay are dissolved in a phosphor whose major solvent usually consists of toluene, toluene-alcohol, or dioxan. Many polymers and low molecular weight compounds are readily soluble in these solvents. Prospective users should not be deterred by alleged complications due to "variable quench effects" as these effects are readily corrected for via internal or external standards or the channels ratio method (7, 46, 91). Dilution quench corrections, though valid, are tedious and unnecessary. Where samples are insoluble in phosphor they may be suspended (e.g. as gels or as paper cut from chromatograms, etc.) or they can be burnt and the combustion products absorbed in a suitable phosphor solution. A modification of the Schoniger flask combustion technique is particularly suitable for this purpose (43—45). 

The use of lithium as a solid compound, a pure melt, or a molten alloy is required for tritium breeding in at least the first generation of fusion reactors. Three fusion reactor concepts are discussed with emphasis on material selection and material compatibility with lithium. Engineering details designed to safely handle molten lithium are described for one of the example concepts. Tritium recovery from the various breeding materials is reviewed. Finally, two aspects of the use of molten Li-Pb alloys are discussed the solubility of hydrogen isotopes, and the influence of the alloy vapor on heavy ion beam propagation. 

Liquid Metal Wall IGF reactors are distinct from other fusion reactors in that the lithium breeding blanket is in direct contact with the plasma exhaust. Thus, the solubility of hydrogen isotopes in the liquid metal will determine whether tritium must be recovered from either the liquid loop or the vacuum system, rather than both systems. 

The contrast between these tracers is rooted in the pronounced meridional asymmetry in the tritium pattern (lower-southern-hemispheric values), compared to the more balanced CEC distribution. Another aspect is the northern midlatitude maximum in tritium compared to a poleward enhancement of CEC-11. The latter is a result of the temperature dependence of CEC solubility, but the former arises from the progressive sequestration of tritium in the subtropical gyres, a phenomenon similar to that of radiocarbon (see Broecker et al., 1985),... 

Catalysts from Group VIII metals have given unsatisfactory results. In the polymerization of butadiene with soluble cobalt catalysts tritium is not incorporated when dry active methanol is employed [115], although it is combined when it has not been specially dried [117, 118]. Alkoxyl groups have been found when using dry alcohol [115, 119] but the reaction is apparently slow and not suited to quantitative work [119]. Side reactions result in the incorporation of tritium into the polymer other than by termination of active chains [118], probably from the addition of hydrogen chloride produced by reaction of the alcohol with the aluminium diethyl chloride [108], Complexes of nickel, rhodium and ruthenium will polymerize butadiene in alcohol solution [7, 120], and with these it has not been possible to determine active site concentrations directly. 

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