Consequences of heavy bombardment for chemical and prebiotic evolution on early Mars and Earth

Tato práce shrnuje pilotní výsledky laboratorního výzkumu vlivu impaktů meziplanetární hmoty na možnou prebiotickou syntézu na raném Marsu. Diskutován je rovněž význam porozumění rané chemii Marsu pro studium chemické evoluce pozemského prostředí, vzniku života na Zemi a přínos studia exoplanet pro tento obor. Navržený scénář prebiotické syntézy dává do souvislosti hypotézu o stěžejní roli impaktů meziplanetární hmoty na chemickou evoluci planet a procesy prebiotické syntézy. Impakt asteroidu je napodoben laserovými jiskrami a post-impaktní termochemie v horkém kráteru je simulována laboratorní termolýzou vzorků v přítomnosti meteoritů, jílů obohacených o železo a dalších minerálů či hornin a jejich směsí vyskytujících se pravděpodobně v impaktních strukturách. Tento výzkum může mít zajímavou souvislost např. se současnými a budoucími výzkumy kráteru Gale. Mineralogie impaktorů je popsána na konkrétním příkladu studia vzácného meteoritu Poranagaba, který díky výzkumu uveřejněném této práci a vědecké publikaci nyní patří mezi vzácných 32 případů meteoritů s rodokmenem. Bylo zjištěno, že meteorit Porangaba je klasický L chondrit bohatý na železo. Patří tedy mezi typické zástupce skupiny meteoritů, jejichž alterací mohou vzniknout na železo bohaté smektity, jejichž zajímavá katalytická aktivita se...The diploma thesis refers to the results of laboratory research dedicated to the influence of extraterestrial matter impacts onto a possible prebiotic synthesis on early Mars. The influence of understanding of early Mars chemistry for proceeding studies of terrestrian chemical habitus evolution and origin of life is discussed, as well as certain advantages to be made of this research within exoplanetary science. The prebiotic synthesis scenario purposed connects the hypothesis comprising a key role of extraplanetary bodies impacts played in the chemical evolution of an early Earth-like planet to the important processes studied within chemical evolution of life. Asteroid impacts are simulated by laser sparks, while post-impact thermochemical processes are mimetized in the laboratory by a controlled termolysis of certain key species in presence of meteorites, iron-rich clays and several other minerals and rocks presumably present in real impact craters. This particular field of research carried is likely to have an interesting application within current and future investigations of the Gale crater. Impactor mineraly is described on a particular example of a rare Porangaba meteorite, which, thanks to this research, has recently been addressed as a member of unique (comprising 32 bodies) family tree...Katedra anorganické chemieDepartment of Inorganic ChemistryFaculty of SciencePřírodovědecká fakult

Analysis of solid samples using calibration free laser induced breakdown spectroscopy - application in metallurgy of meteorites

The aim of this thesis was the development and application of the calibration-free method of the laser induced breakdown spectroscopy (LIBS). The CF-LIBS method is used to quickly analyze of sample of any size and shapes without any required surface treatment, to determinate their elemental composition. In addition, the CF algorithm is also usefull for study of atomic plasma and hot gas emision spectra to determinate their elemental composition. From this point of view, very interesting is ablation analysis of complicated matrices such as meteorites and possible comparsion with spectral analysis of meteors. In the frame of the presented bachelor thesis, was measured the ablation spectra of meteorite samples Porangaba (L4), Chellyabinsk (LL5), Northwest Africa 869 (L3-6) and Dhofar 1994 (CM2). Based on the measured spectra of these meteorites, was created an atlas of the emision lines and assigned parameters of the spectroscopic transitions of the elements, typically occuring in a meteorites. Thisatlas will also serve as the source database for automatic pragram Ablator (automatically evalueting of ablation emission spcectra) and MeteorMaster (automatic program for the interpretation of meteors spectra). The database will be used for CF-LIBS analysis of the Porangaba meteorite. The database is...Cílem práce byl vývoj a aplikace metody bezkalibrační analýzy (CF) spektroskopie laserem indukovaného průrazu (LIBS). Metoda CF-LIBS je používána k rychlé analýze vzorků jakékoliv velikosti, tvaru bez jejich povrchové úpravy za účelem zjištění jejich prvkového složení. Algoritmus CF je navíc použitelný pro studium emisních spekter atomárního plazmatu a horkých plynů rovněž za účelem stanovení jejich prvkového složení. Z tohoto pohledu se jeví velice zajímavá ablační analýza tak komplikovaných matric, jakými jsou meteority a možné porovnávání se spektrální analýzou meteorů. V rámci předkládané bakalářské práce byla naměřena experimentální ablační spektra vzorků meteoritů Porangaba (L4), Čeljabinsk (LL5), Northwest Africa (869) a Dhofaru1994 (CM2). Na základě naměřených spekter těchto meteoritů byl vytvořen atlas emisních linií a jim přiřazených parametrů spektroskopických přechodů prvků, typicky se vyskytujících v meteoritech. Tento atlas bude dále sloužit jako zdrojová databáze pro automatické programy Ablator (automaticky vyhodnocující ablační emisní spektra) a MeteorMaster (automatický program pro interpretaci emisních spekter meteorů). Databáze bude použita pro CF-LIBS analýzu meteoritu Porangaba. Databáze je nutná zejména z hlediska dobře známého ovlivnění ablačních spekter matricí vzorků - pro...Department of Inorganic ChemistryKatedra anorganické chemieFaculty of SciencePřírodovědecká fakult

Simulating asteroid impacts and meteor events by high-power lasers : from the laboratory to spaceborne missions

Meteor plasmas and impact events are complex, dynamic natural phenomena. Simulating these processes in the laboratory is, however, a challenge. The technique of laser induced dielectric breakdown was first used for this purpose almost 50 years ago. Since then, laser-based experiments have helped to simulate high energy processes in the Tunguska and Chicxulub impact events, heavy bombardment on the early Earth, prebiotic chemical evolution, space weathering of celestial bodies and meteor plasma. This review summarizes the current level of knowledge and outlines possible paths of future development.Czech Science FoundationCzech Academy of Sciences Program of Regional Cooperatio

Ariel – a window to the origin of life on early earth?

Is there life beyond Earth? An ideal research program would first ascertain how life on Earth began and then use this as a blueprint for its existence elsewhere. But the origin of life on Earth is still not understood, what then could be the way forward? Upcoming observations of terrestrial exoplanets provide a unique opportunity for answering this fundamental question through the study of other planetary systems. If we are able to see how physical and chemical environments similar to the early Earth evolve we open a window into our own Hadean eon, despite all information from this time being long lost from our planet’s geological record. A careful investigation of the chemistry expected on young exoplanets is therefore necessary, and the preparation of reference materials for spectroscopic observations is of paramount importance. In particular, the deduction of chemical markers identifying specific processes and features in exoplanetary environments, ideally “uniquely”. For instance, prebiotic feedstock molecules, in the form of aerosols and vapours, could be observed in transmission spectra in the near future whilst their surface deposits could be observed from reflectance spectra. The same detection methods also promise to identify particular intermediates of chemical and physical processes known to be prebiotically plausible. Is Ariel truly able to open a window to the past and answer questions concerning the origin of life on our planet and the universe? In this paper, we discuss aspects of prebiotic chemistry that will help in formulating future observational and data interpretation strategies for the Ariel mission. This paper is intended to open a discussion and motivate future detailed laboratory studies of prebiotic processes on young exoplanets and their chemical signatures

Consequences of heavy bombardment for chemical and prebiotic evolution on early Mars and Earth

The diploma thesis refers to the results of laboratory research dedicated to the influence of extraterestrial matter impacts onto a possible prebiotic synthesis on early Mars. The influence of understanding of early Mars chemistry for proceeding studies of terrestrian chemical habitus evolution and origin of life is discussed, as well as certain advantages to be made of this research within exoplanetary science. The prebiotic synthesis scenario purposed connects the hypothesis comprising a key role of extraplanetary bodies impacts played in the chemical evolution of an early Earth-like planet to the important processes studied within chemical evolution of life. Asteroid impacts are simulated by laser sparks, while post-impact thermochemical processes are mimetized in the laboratory by a controlled termolysis of certain key species in presence of meteorites, iron-rich clays and several other minerals and rocks presumably present in real impact craters. This particular field of research carried is likely to have an interesting application within current and future investigations of the Gale crater. Impactor mineraly is described on a particular example of a rare Porangaba meteorite, which, thanks to this research, has recently been addressed as a member of unique (comprising 32 bodies) family tree..

Analysis of solid samples using calibration free laser induced breakdown spectroscopy - application in metallurgy of meteorites

The aim of this thesis was the development and application of the calibration-free method of the laser induced breakdown spectroscopy (LIBS). The CF-LIBS method is used to quickly analyze of sample of any size and shapes without any required surface treatment, to determinate their elemental composition. In addition, the CF algorithm is also usefull for study of atomic plasma and hot gas emision spectra to determinate their elemental composition. From this point of view, very interesting is ablation analysis of complicated matrices such as meteorites and possible comparsion with spectral analysis of meteors. In the frame of the presented bachelor thesis, was measured the ablation spectra of meteorite samples Porangaba (L4), Chellyabinsk (LL5), Northwest Africa 869 (L3-6) and Dhofar 1994 (CM2). Based on the measured spectra of these meteorites, was created an atlas of the emision lines and assigned parameters of the spectroscopic transitions of the elements, typically occuring in a meteorites. Thisatlas will also serve as the source database for automatic pragram Ablator (automatically evalueting of ablation emission spcectra) and MeteorMaster (automatic program for the interpretation of meteors spectra). The database will be used for CF-LIBS analysis of the Porangaba meteorite. The database is..

Decomposition of Benzene during Impacts in N2-dominated Atmospheres

Benzene is a simple neutral aromatic compound found in molecular clouds, comets, and planetary atmospheres. It has been confirmed on Jupiter, Saturn, Titan, and is expected on exoplanets. In this paper, the decomposition of benzene in a simulated asteroid or comet impact into an N _2 -dominated atmosphere was investigated. The impact plasma was simulated with laser-induced dielectric breakdown and the gas phase decomposition products were observed using high-resolution Fourier transform infrared spectroscopy. The gas phase decomposition products involve mainly HCN, C _2 H _2 , and smaller amounts of CH _4 with yields of 3.1%–24.0%, 0–11.7%, and 0.5%–3.3%, respectively. Furthermore, in presence of water, benzene also produces CO and CO _2 with yields of 2.4%–35.1% and 0.01%–4.8%, respectively. The oxidation state of the product mixture is proportional to the water content. Apart from that, a black-brownish solid phase is formed during the experiments, which makes up about 60% of the original carbon content. Our results therefore show that in anoxic N _2 -dominated planetary atmospheres, impacts might lead to the depletion of benzene and the formation of HCN, C _2 H _2 , and CH _4 and, in the presence of water, to the formation of CO and CO _2

Quantum Dots in Peroxidase-like Chemistry and Formamide-Based Hot Spring Synthesis of Nucleobases

Quantum dots (QDs) are usually seen as artificial semiconductor particles exhibiting optical and electronic properties interesting for nanotechnological applications. However, they may also play a role in prebiotic chemistry. Starting from zinc acetate, cadmium acetate, and mercaptosuccinic acid, we demonstrate the formation of ZnCd QDs upon UV irradiation in prebiotic liquid formamide. We show that ZnCd QDs are able to increase the yield of RNA nucleobase synthesis from formamide up to 300 times, suggesting they might have served as universal catalysts in a primordial milieu. Based on the experimentally observed peroxidase-like activity of ZnCd QDs upon irradiation with visible light, we propose that QDs could be relevant to a broad variety of processes relating to the emergence of terrestrial life

Prebiotic route to thymine from formamide - A combined experimental–theoretical study

Synthesis of RNA nucleobases from formamide is one of the recurring topics of prebiotic chemistry research. Earlier reports suggest that thymine, the substitute for uracil in DNA, may also be synthesized from formamide in the presence of catalysts enabling conversion of formamide to formaldehyde. In the current paper, we show that to a lesser extent conversion of uracil to thymine may occur even in the absence of catalysts. This is enabled by the presence of formic acid in the reaction mixture that forms as the hydrolysis product of formamide. Under the reaction conditions of our study, the disproportionation of formic acid may produce formaldehyde that hydroxymethylates uracil in the first step of the conversion process. The experiments are supplemented by quantum chemical modeling of the reaction pathway, supporting the plausibility of the mechanism suggested by Saladino and coworkers

High-Dose-Rate Brachytherapy as an Organ-Sparing Treatment for Early Penile Cancer

Background: Low-dose-rate brachytherapy is an effective organ-sparing treatment for patients with early-stage penile cancer. However, only limited data are available on the role of high-dose-rate brachytherapy (HDR-BT) in this clinical setting. Methods: Between 2002 and 2020, 31 patients with early penile cancer were treated at our center with interstitial HDR BT at a dose of 18 × 3 Gy twice daily. A breast brachytherapy template was used for the fixation of stainless hollow needles. Results: The median follow-up was 117.5 months (range, 5–210). Eight patients (25.8%) developed a recurrence; of these, seven were salvaged by partial amputation. Six patients died of internal comorbidities or a second cancer. The probability of local control at 5 and 10 years was 80.7% (95% CI: 63.7–97.7%) and 68.3% (95% CI: 44.0–92.6%), respectively. Cause-specific survival was 100%. Only one case of radiation-induced necrosis was observed. The probability of penile sparing at 5 and 10 years was 80.6% (95% CI: 63.45–97.7%) and 62.1% (95% CI: 34.8–89.4%), respectively. Conclusions: These results show that HDR-BT for penile cancer can achieve results comparable to LDR-BT with organ sparing. Despite the relatively large patient cohort—the second largest reported to date in this clinical setting—prospective data from larger samples are needed to confirm the role of HDR-BT in penile cancer