Collectivism in a Replication Network of Minimal Nucleobase Sequences

A major challenge for understanding the origins of life is to explore how replication networks can engage in an evolutionary process. Herein, we shed light on this problem by implementing a network constituted by two different types of extremely simple biological components: the amino acid cysteine and the canonical nucleobases adenine and thymine, connected through amide bonds to the cysteine amino group and oxidation of its thiol into three possible disulfides. Supramolecular and kinetic analyses revealed that both self- and mutual interactions between such dinucleobase compounds drive their assembly and replication pathways. Those pathways involving sequence complementarity led to enhanced replication rates, suggesting a potential bias for selection. The interplay of synergistic dynamics and competition between replicators was then simulated in an open reactor with experimental kinetic data, showing the selective amplification of different species depending on the initial mixture composition. Overall, this network configuration can favor a collective adaptability to changes in the availability of feedstock molecules, with disulfide exchange reactions serving as 'wires' that connect the different individual auto- and cross-catalytic pathways.

Formation of Mixed Supramolecular Complexes Oxygen-Isoprene in Pulsed Supersonic Jet

An experimental study of the formation of mixed van der Waals oxygen-isoprene complexes, generated in an expanding supersonic helium-oxygen-isoprene jet at various stagnation pressures and at diverse oxygen and isoprene concentrations, has been performed. The particularities of applying mass spectrometry to studying clustered isoprene streams in a pulsed mode have been discussed. The composition of small clusters generated in a free supersonic jet has been checked for dependencies upon the initial mixture composition and stagnation pressure. The mechanism of nucleation has been identified for different partial concentrations of impurities in the helium stream. The specific features of the dissociative ionization of van der Waals complexes, consisting of pure isoprene and mixed complexes, have been discussed. The conditions needed for the formation of binary oxygen-isoprene van der Waals complexes have been identified

Analysis of Spray Tests in a Multi-Compartment Geometry Using the GOTHIC Code

The effect of spray on the gas mixing in the multi-compartment geometry of the PANDA facility is investigated using the GOTHIC code. Two tests using two connected vessels are analysed, where water was injected from a full-cone spray nozzle placed in the upper part of one vessel. In the vessel where the spray was located, the upper region was filled with a helium-rich mixture. The remaining volume of the vessel and the second vessel were filled with a denser fluid. The difference between the two tests was the presence of air: one test was performed with steam and helium only, whereas in the second test air was also present in the gas mixture in both vessels. These experiments have been analysed with the advanced containment code GOTHIC. The results showed that the code tends to overpredict the depressurisation rate when the standard correlations for natural convection heat transfer between fluid and structures are used. With respect to mixing, generally good results were obtained. The timing of the stratification break-up above the nozzle injection, however, could not be reproduced. Finally, the large effect of the initial mixture composition on the evolution of the gas distribution in the connected vessel was well predicted.