Prompt initial enrichment

For years, it has been known that some of the oldest open clusters, such as NGC 188, had roughly solar metallicity, but increasing samples have shown clearly that there is no relationship between overall cluster metallicity and age ([3,10,6,11]) in the solar neighborhood. The existence of clusters like NGC 6791, a 9 Gyr old cluster with metallicity twice solar, requires prompt initial enrichment of the Galactic disk, at least in the solar neighborhood. The metallicity of open clusters depends much more strongly on their position in the disk than on their age. 

Fig. 8.40. Magnesium abundance distribution functions for the thick and thin disks. Histograms Fe/H distributions from Wyse and Gilmore (1995) converted to Mg/H from the relations found by Fuhrmann (1998). Curves dashed, simple inflow model (Eqs. 8.46 to 8.52) for the thick disk dotted, prompt initial enrichment model plus inflow for the thin disk short-dash-dotted, inflow model without PIE long-dash-dotted, PIE without inflow. After Pagel in E. Vangioni-Flam et al. (2001). Copyright by World Scientific.

BASIC PULSE-CHASE KINETICS. For the case of a single pool of A that becomes promptly labeled with tracer A, bolus administration of tracer will initially increase the tracer/tracee ratio (indicated by the initial isotopic enrichment Eo), which will subsequently suffer exponential decay As is the case for all first-order processes, the rate law is ... 

The rich chemistry of the coal polyanion and the presumably close relationship between the structures of the coal polyanion and the initial coal molecules prompted us to study the reaction conditions and the reaction products carefully and then to examine the reaction of the coal polyanion with 90%-enriched butyl-l- C iodide. 

---