K/La ratios

As the HTC does not contain low-temperature elements like potassium etc., we assume that the Moon and the other objects whose K/La ratio differs from the chondritic value consist of a mixture of HTC and a component containing low-temperature elements. 

With the above assumption, it is easy to calculate the absolute elemental abundances of the Moon from the observed K/La ratio in the lunar samples and the concentrations of K and La both in the HTC (as analyzed in the Allende inclusions) and in normal chondrites. 

Fig. 14. Uranium is refractory like the rare earths, so that K/U ratios are an analogue for K/La ratios (fig. 11). K and U data are available for a wide variety of solar system material, since both elements are readily determined by gamma-ray spectroscopy. Both are incompatible in igneous processes and so tend to preserve their bulk planetary ratios during differentiation. This diagram illustrates that substantial volatile element depletion was widespread in the inner solar nebula, so that similar variations to K/U in volatile element/rare earth ratios are lo be expected. (From Taylor 1987a.)...

For elements of the second transition series and beyond, a choice of lines is often available, with, for example, K and L lines in the second transition series and M and L lines in the third. The high-energy lines were normally used for the analysis because of their lower absorption cross sections (33), and LocKa or M La ratios were used to monitor crystal thickness (see below). The most straightforward analyses are those involving elements with approximately the same atomic numbers, when the K K or L L ratios may be used and the absorption cross sections are normally of similar magnitude (although difficulties can arise if an emission from one element leads to fluorescence from another). For elements that are far removed from each other in the periodic table, mixed ratios... 

The first reaction of oxidation of ferrocene occurs at an electrode followed by oxidation of GO(red) in solution with the pesudo-first-order rate constant f=/j[GO(red)]. The values k(la (a = nFv/RT v is a scan rate) estimated from the experimentally measured i ji ratios (Fig. 2) using the Nicholson and Shain approach (73) have been... 

However, these meteorites are depleted in aluminum relative to terrestrial rocks, a characteristic shared by martian soils and the Mars Pathfinder dust-free rock (Figure 5). Ratios of volatile to refractory elements (e.g., K/La) are constant but higher than in terrestrial or lunar rocks (Figure 6). 

BET areas for reduced catalysts are in parenthesis Catalysts reduced at 1023 K under Hi (33%) in Ar For Co/La ratio measurement all Co signals (reduced, oxidised forms and shake-up lines) were included. 

I, 277 ppm Ce giving an average Ce/La ratio of 4.5. This is intermediate between the ratios in nodules from the Aitutaki Passage (Area K) and the C.C. FZ (Area C) and is compatible with a hydrogenous origin for these cmsts. 

It was previously proposed that surface-carbonate compounds are reaction intermediates during catal34ic soot combustion (1,2). In this vein. High Frequency CO2 Pulses technique provides not only information about the stability of the surface, but also about the dynamics of the intermediate compound formation and decomposition. While XPS characterization shows that K/La surface ratio increases when increasing calcination temperature, results shown in Fig. 1 indicate that the CO2- surface interaction decreases. 

The chemical analysis of ALHA 81005 in Table 18.10 and the data contained in the report by Hill et al. (1991) define a field for lunar meteorites and lunar basalt in Fig. 18.25 in terms of the Fe/Mn, K/La, and Fe/Sc ratios. Data point 1 in that diagram identifies ALHA 81005 and point 2 is the Calkalong lunar meteorite. The locations of these data points within the cluster of lunar rocks (open circles) that were collected on the Moon by the Apollo astronauts leaves no doubt that ALHA 81005 and Calkalong are rocks from the Moon. The diagram also contains a field defined by HED achondrites (howardites, eucrites. 

Fig. 18.25 Lunar basalt (open circles) collected by the Apollo astronauts and lunar meteorites (solid circles) collected in Antarctica occupy a well-defined area in coordinates of their Fe/ Mn, K/La, and (Fe/Sc) x 0.01 ratios. The achondrites of the HED (Howardite, Eucrite, Diogenite) groups (crosses) lie in a separate field. The SNC (solid triangles) meteorites (Shergottites, Nakhlites, Chassignites) originated from Mars. The sample numbered 1 is ALHA 81005 and 2 is Calkalong which was recovered in the Australian desert. The Fe/Sc ratio was reduced by a factor or 0.01 in order to prevent the data points from crowding into the Fe/Sc corner of the triangle (Data for ALHA 81005 from Korotev et al. 1983 and for the other samples from Hill et al. 1991)...

Weight - That force which, when applied to a body, would give it an acceleration equal to the local acceleration of gravity. [1] Wiedeman-Franz law - The law stating that the thermal conductivity k and electrical conductivity o of a pure metal are related by k = La T, where T is the temperature and L (called the Lorenz ratio) has the approximate value 2.45 x 10" V /K . Wien displacement law - The relation, which can be derived from the Planck formula for black body radiation, that... 

The enantioselectivity of biocatalytic reactions is normally expressed as the enantiomeric ratio or the E value [la], a biochemical constant intrinsic to each enzyme that, contrary to enantiomeric excess, is independent of the extent of conversion. In an enzymatic resolution of a racemic substrate, the E value can be considered equal to the ratio of the rates of reaction for the two enantiomers, when the conversion is close to zero. More precisely, the value is defined as the ratio between the specificity constants (k st/Ku) for tho two enantiomers and can be obtained by determination of the k<-at and Km of a given enzyme for the two individual enantiomers. 

The effect of the H-Beta ratio (y in wt%) in the dual-bed Pt/Z12(x) HB(y) catalyst system on the benzene purity at a reaction temperature (Tr) of 623 K is shown in Fig. 1. It is evident that the benzene purity gradually increased with increasing H-Beta ratio (Fig. la), eventually reaching a plateau value which meets the industrial specification of 99.85% at y 40 wt%. The effects of catalyst bed ratio on product yields are shown in Fig. lb. Comparing to the single-bed catalyst Pt/Z 12 (i.e., y = 0), the overall premium product yields of benzene and xylene (A68 yield) over the dual-bed catalyst Pt/Z12(x) HB(y) system reached an maximum at y 10 wt%. That the A68 yield dwindled and tetramethylbenzene (TEMB) increased with further increase in the H-Beta ratio may be attributed to the larger pore opening possessed by the bottom (H-beta) catalyst, which may provoke disproportionation of TMB to form tetramethylbenzene (TEMB) [8],... 

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