RESUMEN
We show that the nucleic acid bases adenine, cytosine, guanine, thymine, and uracil, as well as 2,6-diaminopurine, and the "core" nucleic acid bases purine and pyrimidine, are stable for more than one year in concentrated sulfuric acid at room temperature and at acid concentrations relevant for Venus clouds (81% w/w to 98% w/w acid, the rest water). This work builds on our initial stability studies and is the first ever to test the reactivity and structural integrity of organic molecules subjected to extended incubation in concentrated sulfuric acid. The one-year-long stability of nucleic acid bases supports the notion that the Venus cloud environment-composed of concentrated sulfuric acid-may be able to support complex organic chemicals for extended periods of time.
RESUMEN
What constitutes a habitable planet is a frontier to be explored and requires pushing the boundaries of our terracentric viewpoint for what we deem to be a habitable environment. Despite Venus' 700 K surface temperature being too hot for any plausible solvent and most organic covalent chemistry, Venus' cloud-filled atmosphere layers at 48 to 60 km above the surface hold the main requirements for life: suitable temperatures for covalent bonds; an energy source (sunlight); and a liquid solvent. Yet, the Venus clouds are widely thought to be incapable of supporting life because the droplets are composed of concentrated liquid sulfuric acid-an aggressive solvent that is assumed to rapidly destroy most biochemicals of life on Earth. Recent work, however, demonstrates that a rich organic chemistry can evolve from simple precursor molecules seeded into concentrated sulfuric acid, a result that is corroborated by domain knowledge in industry that such chemistry leads to complex molecules, including aromatics. We aim to expand the set of molecules known to be stable in concentrated sulfuric acid. Here, we show that nucleic acid bases adenine, cytosine, guanine, thymine, and uracil, as well as 2,6-diaminopurine and the "core" nucleic acid bases purine and pyrimidine, are stable in sulfuric acid in the Venus cloud temperature and sulfuric acid concentration range, using UV spectroscopy and combinations of 1D and 2D 1H 13C 15N NMR spectroscopy. The stability of nucleic acid bases in concentrated sulfuric acid advances the idea that chemistry to support life may exist in the Venus cloud particle environment.
Asunto(s)
Bivalvos , Venus , Adenina , Agresión , Ácidos SulfúricosRESUMEN
Those charged with assessing and managing threatening communications must utilize risk factors that are behavioral, operational, and reasonably attainable during investigations. This project examined 326 written correspondence cases of an inappropriate, disruptive, or threatening nature that targeted political officials, with the specific goal of identifying written content indicators of problematic approach behavior. Results revealed that subjects who engaged in problematic approach activity toward their targets had more criminal history, past threat assessment activity, familiarity with firearms, past substance use, and indicators of serious mental illness. Approachers were more likely to engage in multiple contact methods, target dispersion, more overall contacts, and prior contact with their target. Numerous content themes were associated with future problematic approach, including longer handwritten correspondence, referencing specific events, making demands, mentioning stressors, focus on personal themes, feeling their rights were violated, and expressing an intention to approach. Harassing, insulting, and threatening language was not related to approach behavior. The implications of these findings are wide-ranging for the practice of threat assessment.