Self-enrichment

Abstract. I present preliminary results for a sample of 700 red giants in u> Cen, observed during the Ital-FLAMES Consortium GTO time in May 2003, for the Bologna Project on u Cen. Preliminary Fe and Ca abundances confirm previous results while the metal-poor and intermediate populations show a normal halo o-enhancement of [a/Fe] +0.3, the most metal-rich stars show a significantly lower [a/Fe] +0.1. If the metal-rich stars have evolved within the cluster in a process of self-enrichment, the only way to lower their a-enhancement would be SNe type la intervention. 

Spectroscopic observations of globular clusters (GCs) have revealed star-to-star inhomogeneities in the light metals that are not observed in field stars. These light metal anomalies could be interpreted with a self-pollution scenario. But what about heavier (Z > 30) elements Do they also show abundance anomalies Up to now, no model has been developed for the synthesis of n-capture elements in GCs, and the self-pollution models do not explain the origin of their metallicity. In 1988, Truran suggested a test for the self-enrichment scenario [4], which could possibly explain the metallicity and the heavy metal abundances in GCs if self-enrichment occurred in GCs, even the most metal-rich clusters would show both high [a/Fe] ratios and r-process dominated heavy elements patterns, which characterize massive star ejecta as it is seen in the most metal-poor stars. 

Regardless of the details concerning self-enrichment and winds, the existence of isolated star formation bursts will also affect the iron-oxygen and iron-a relations, introducing scatter in Fe/O and possibly gaps in the iron abundance distribution function. When the interval between successive bursts exceeds the evolution time for SN la (maybe about 1 Gyr), iron will build up in the ISM resulting in an enhanced Fe/O ratio in the second burst so that one can end up with [Fe/O] > 0 (Gilmore Wyse 1991) see Fig. 8.7. 

Another idea under investigation can be labeled self enrichment of the molecular cloud. The idea uses the observation that in a giant molecular cloud, serial star formation may occur, where the massive stars in the first batch of stars to form explode as supernova and trigger a second round of star formation, the massive stars of which explode and trigger yet another round of star formation. As each supernova explodes, it dumps short-lived nuclides... 

Programs such as this and the IISME Program from the Lawrence Hall of Science (9) directly impact the lives of teachers and their students. We feel that the project promotes professional development of teachers by concentrating their efforts on applications to the classroom and the self enrichment and fulfillment achieved through sharing with colleagues. 

In a book that sparkles with verve, life, and practicality, Dr. Cavalli explains how alchemy was one of humankind s earliest efforts to transform the nature of consciousness. What little- known or underground arts did alchemists practice in pursuit of self-transformation-and how can they enrich us today ... 

Self-assembly of the precursor components in the EISA process starts after evaporation of part of the volatile solvent, which progressively enriches the solution with respect to surfactant, precursor, and water. When their concentration in the deposited him achieves a certain critical level, mesostructure formation takes place. The latter is in equilibrium with the processing atmosphere. So the relative humidity, as well as the temperature during him deposition, represent some of the most important parameters influencing the mesostructure formation. 

The dependence of this phenomenon on temperature and concentration has been studied in detail (70,71,87) and treated mathematically (87). In principle any compound capable of self-association might be capable of self-induced nonequivalence. These cases should be sufficient to suggest due caution on the part of those who would establish the identity of a racemate (e.g., a synthetic natural product ), by comparison of its NMR spectrum with that of the naturally derived optically pure substance. This phenomenon is not restricted to solutes with aromatic substituents, as evidenced by Table 12. Self-induced nonequivalence may be eliminated by addition of polar solvents or by dilution of the sample. Under these conditions, as has been shown for dihydroquinine (14), spectra of racemic, optically pure, and enriched material become identical. 

The more successful strategy for the isolation of RNA- and DNA-based catalysts involves the direct screening of nucleic acids libraries for catalytic activity. This approach is called direct selection [6, 65, 77, 78, 86, 101-107]. In direct selections, nucleic acids that are capable of catalyzing a particular chemical transformation modify themselves with a tag or other characteristic that allows their preferential enrichment over those molecules which are catalytically inactive [108]. The design of ribozyme-selections involving reactions between two small substrates requires that one reactant be covalently attached to every individual member of the starting RNA pool. After the reaction with another substrate which usually carries the selection-tag has occurred, the self-modified RNA is immobilized on a solid support, separated from non-active molecules, and then cleaved off the support. 

Two important areas of research are underway to improve further the hybrid UV-03/soil disposal system. A UV monitor coupled with a computer is under investigation to make the unit self contained with regard to chemical analyses and to automate certain functions of the photochemical phase. Second, a microbial enrichment investigation utilizing UV-O3 products as substrates is in progress to select and possibly engineer degradators to accelerate the microbial phase. 

All in all, the continued growth of computer power and development of theory and its algorithmic implementation will enable more physics e.g. van der Waals interactions, electron self-interaction, entropic effects) to be correctly captured and enable ultimately more speedy, accurate, and comprehensive (multi-scale and multi-phasic) simulations. Theory will be an ever more indispensible ally of experiment and continue to supply detail knowledge on molecular transformations, thereby propelling the growth of heterogeneous catalysis and enriching our world in years to come. 

---