Nejdůležitější odborné publikace vydané během druhého období (do 31. září 2019). Seznam všech publikací výzkumného programu CHEMISTRY vydaných v rámci projektu CAAS najdete na zvláštní stránce, seznam nejdůležitějších publikací za první období pak zde.
Prebiotic synthesis initiated in formaldehyde by laser plasma simulating high-velocity impacts
M. Ferus, F. Pietrucci, A. M. Saitta, O. Ivanek, A. Knizek, P. Kubelík, M. Krus, L. Juha, R. Dudzak, J. Dostál, A. Pastorek, L. Petera, J. Hrncirova, H. Saeidfirozeh, V. Shestivská, J. Sponer, J. E. Sponer, P. Rimmer, S. Civiš and G. Cassone
Astronomy & Astrophysics, Volume 626, June 2019, Article Number A52, Section Atomic, molecular, and nuclear data
Published online 12 June 2019
Context. It is well known that hydrogen cyanide and formamide can universally be considered as key molecules in prebiotic synthesis. Despite the fact that formamide has been detected in interplanetary and interstellar environments, other prebiotic species are far more abundant, including, for example, formaldehyde. However, several results indicate that formamide can play the role of important intermediate as well as that of a feedstock molecule in chemical abiogenesis. Diverse recently proposed scenarios of the origins of the first biopolymers show that liquid formamide environments could have been crucial for the formation of nucleobases, nucleosides, and for phosphorylation reactions, which lead to nucleotides.
Aims. Here we report on a wide exploration of the formaldehyde reaction network under plasma conditions mimicking an asteroid descent in an Earth-like atmosphere and its impact.
Methods. Dielectric breakdown using a high-power kJ-class laser system (PALS – Prague Asterix Laser System) along with quantum mechanical, ab initio molecular dynamics, and enhanced sampling simulations have been employed in order to mimic an asteroid impact plasma.
Results. Being more abundant than formamide both in interstellar and interplanetary environments, during the era of early and late heavy bombardment of Earth and other planets, formaldehyde might have been delivered on asteroids to young planets. In the presence of nitrogen-bearing species, this molecule has been reprocessed under plasma conditions mimicking the local environment of an impacting body. We show that plasma reprocessing of formaldehyde leads to the formation of several radical and molecular species along with formamide.
Conclusion. All the canonical nucleobases, the simplest amino acid (i.e., glycine), and the sugar ribose, have been detected after treatment of formaldehyde and nitrogen gas with dielectric breakdown. Our results, supported by quantum mechanical and enhanced sampling simulations, show that formaldehyde – by producing inter alia formamide – may have had the role of starting substance in prebiotic synthesis.
Recycling of isotopically modified molybdenum from irradiated CerMet nuclear fuel: part 1—concept design and assessment
Kamil Vavřinec Mareš & Jan John
Journal of Radioanalytical and Nuclear Chemistry volume 320, pages 227–233 (2019)
Published: 23 February 2019
This paper deals with concept design and assessment of a process for the recovery of isotopically modified molybdenum from irradiated nuclear CerMet fuels containing the transuranium element oxides in a metallic molybdenum matrix. The recovery of isotopically modified Mo should enable re-use of this valuable resource especially in the case of uranium-free fuels/targets for accelerator-driven transmuters. The process concept proposed is a modification of the standard hydrometallurgical way of molybdenum processing. Further, the most significant expected radionuclidic impurities in the molybdate raffinate were predicted. Separation of these impurities from the concentrated molybdate solution will be described in the following parts of this mini-series.