Equilibria beta-values

Beta values represent the fraction of free atoms present in the hot flame gases of the flame indicated. These values have been taken from various sources and were either experimentally measured or calculated from thermodynamic data using the assumption of local thermodynamic equilibrium in the flame. These values do not have very good agreement within each element however, the values do provide an indication of the probable sensitivity of the particular flame. 

C = crystallized P = purified. Parentheses indicate an assumed value. Calculated from S h Dto, and V. Range of components reported to have beta-amylase activity molecular weights, only, estimated from Sso- Three distinct components firom barley malt. From sedimentation equilibrium measurements. Value quoted from a personal communication from M. Burr and D. Yphantis. Three distinct components firom wheat. 

Gr. aktis, aktinos, beam or ray). Discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902. Occurs naturally in association with uranium minerals. Actinium-227, a decay product of uranium-235, is a beta emitter with a 21.6-year half-life. Its principal decay products are thorium-227 (18.5-day half-life), radium-223 (11.4-day half-life), and a number of short-lived products including radon, bismuth, polonium, and lead isotopes. In equilibrium with its decay products, it is a powerful source of alpha rays. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300-degrees G. The chemical behavior of actinium is similar to that of the rare earths, particularly lanthanum. Purified actinium comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.6-year half-life. It is about 150 times as active as radium, making it of value in the production of neutrons. 

A knowledge of the mechanisms of al-pha-beta conversions can be expected to yield some insight into the factors responsible for the relative values of the velocity constants for the forward kf, and reverse kr, reactions which fix the equilibrium constant, Ke = kf/kr. Theoretically, the anomer-ization of a sugar derivative can proceed in several different ways. The four routes which follow appear the most plausible. 

The acid-base equilibrium constants of the beta-blockers atenolol, oxprenolol, timolol, and labetalol were determined by automated potentiometric titrations. The pKg values were obtained in water-rich or water methanol medium (20% MeOH) to obviate the solubility problems associated with the compounds. The initial estimates of pKa values were obtained from Gran s method and then, were refined by the NYTIT and ZETA versions of the LETAGROP computer program. The resultant values were 9.4 (/ = 0.1 M KCI, 20% methanol) for atenolol, 9.6 (/ = 0.1 M KCI) for oxprenolol, 9.4 (/ = 0.1 M KCI, 20% methanol) for timolol and 7.4 and 9.4 (/ = 0.1 M KCI) for labetalol. The potentiometric method was found to be accurate and easily applicable. The operational criteria for applying the methodology are indicated. 

For the gas saturation method, the error sources and their approximate values are very similar to previous column techniques. [At 95% confidence, temperature control = +0.05°K (normal), lack of vapor-liquid equilibrium = -5% (beta), trapping efficiency =... 

Tritium and Li production were calculated for the reference AHTR configuration. The overwhelmingly dominant reactions are the Li(n, a) H reaction and the Be(n, a) He reaction with subsequent beta decay to Li. At 2400 MW(t), the equilibrium Li concentration in the coolant is 0.001 wt %, or about 10% of its initial concentration. This is due to the burnout of the initial Li loading balanced by the generation of new Li from the Be reaction. At this equilibrium concentration, tritium production is -500 Ci/day. However, the exponential decay constant for the Li concentration is -460 days, which means that it will take several years for the Li concentration and, hence, the tritium production rate, to reach an equilibrium value. The initial tritium production will be on the order of 5000 Ci/day. For comparison, an LWR produces -50 Ci/day, and a typical heavy water reactor produces 3500-6000 Ci/day. ... 

---