Search results for "chemical evolution"
showing 3 items of 13 documents
Ultrahigh- resolving analytics in meteoritic soluble organic matter
2016
International audience; No abstract
The young hard active Sun: soft X-ray irradiation of tryptophan in water solutions
2010
AbstractThe X-ray emission of the young Sun was much harder and intense than today and might have played a significant role in the evolution of complex organics in protoplanetary environments. We investigate the effects of soft X-rays on tryptophan molecules in aqueous solutions at room temperature. As results of the irradiation experiments we detect several light species indicative of fragmentation, together with large molecular structures such as tryptophan dipeptide and tripeptide. Complexification is more evident in H2O solution than in D2O, probably due to isotopic effects. The abundances of peptides depend on the irradiation dose and decrease with increasing energy deposition. Radical…
Melt extraction and accumulation from partially molten rocks
2004
Current models for melt segregation and ascent are not adequate to accurately describe transport and accumulation in combination. We propose that transport is discontinuous and in batches, and that accumulation occurs by stepwise merging of batches. A simple numerical model of jostling spheres that merge when they touch was used to represent stepwise accumulation and transport of batches by propagation of hydrofractures. Results of the numerical model indicate that such a system may quickly develop into a self-organised critical (SOC) state. In this state, the distribution of melt batch volumes can be described by a power law, with an exponent m that lies between 2/3 and 1. Once a self-orga…