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Wesołowska O, Duda-Madej A, Błaszczyk M, Środa-Pomianek K, Kozłowska J, Anioł M. Interaction of selected alkoxy naringenin oximes with model and bacterial membranes. Biomed Pharmacother 2024; 174:116581. [PMID: 38636394 DOI: 10.1016/j.biopha.2024.116581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/05/2024] [Accepted: 04/10/2024] [Indexed: 04/20/2024] Open
Abstract
Naringenin is a flavonoid found in many fruits and herbs, most notably in grapefruits. In recent years, this compound and its derivatives have been of great interest due to their high biological activity, including fungicidal and bactericidal effects, also in relation to multidrug-resistant bacteria. Membrane interactions of naringenin oxime (NO) and its 7-O-alkyl (7-alkoxy) derivatives, such as methyl (7MENO), ethyl (7ETNO), isopropyl (7IPNO), n-butyl (7BUNO) and n-pentyl (7PENO) were studied. Thermotropic properties of model membranes were investigated via differential scanning calorimetry (DSC), the influence on lipid raft mimicking giant unilamellar vesicles (GUVs) via fluorescence microscopy, and membrane permeability via measuring calcein leakage from liposomes. Molecular calculations supplemented the study. The influence of naringenin oximes on two strains of multidrug resistant bacteria: Staphylococcus aureus KJ and Enterococcus faecalis 37VRE was also investigated. In DSC studies all compounds reduced the temperature and enthalpy of main phase transition and caused disappearing of the pretransition. NO was the least active. The reduction in the area of surface domains in GUVs was observed for NO. Compounds NO and 7BUNO resulted in very low secretion of calcein from liposomes (permeability < 3 %). The highest results were observed for 7MENO (88.4 %) and 7IPNO (78.5 %). When bacterial membrane permeability was investigated all compounds caused significant release of propidium iodide from S. aureus (31.6-87.0 % for concentration 128 μg/mL). In the case of E. faecalis, 7ETNO (75.7 %) and NO (28.8 %) were the most active. The rest of the tested compounds showed less activity (permeability < 13.9 %). The strong evidence was observed that antibacterial activity of the tested compounds may be associated with their interaction with bacterial membrane.
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Affiliation(s)
- Olga Wesołowska
- Department of Biophysics and Neuroscience, Faculty of Medicine, Wroclaw Medical University, Wrocław, Poland.
| | - Anna Duda-Madej
- Department of Microbiology, Faculty of Medicine, Wroclaw Medical University, Poland
| | - Maria Błaszczyk
- Department of Biophysics and Neuroscience, Faculty of Medicine, Wroclaw Medical University, Wrocław, Poland
| | - Kamila Środa-Pomianek
- Department of Biophysics and Neuroscience, Faculty of Medicine, Wroclaw Medical University, Wrocław, Poland
| | - Joanna Kozłowska
- Department of Biocatalysis and Food Chemistry, The Faculty of Biotechnology and Food Science, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Mirosław Anioł
- Department of Biocatalysis and Food Chemistry, The Faculty of Biotechnology and Food Science, Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
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Boulesteix D, Buch A, Samson J, Freissinet C, Coscia D, He Y, Teinturier S, Stern JC, Trainer MG, Szopa C. Dimethylformamide dimethyl acetal reagent for in situ chiral analyses of organic molecules on Titan with the Dragonfly mass spectrometer space instrument (Dragonfly mission). J Chromatogr A 2024; 1722:464860. [PMID: 38593521 DOI: 10.1016/j.chroma.2024.464860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/11/2024] [Accepted: 03/30/2024] [Indexed: 04/11/2024]
Abstract
Thanks to the Cassini-Huygens space mission between 2004 and 2017, a lot was learned about Titan, the biggest satellite of Saturn, and its intriguing atmosphere, surface, and organic chemistry complexity. However, key questions about the potential for the atmosphere and surface chemistry to produce organic molecules of direct interest for prebiotic chemistry and life did not find an answer. Due to Titan potential as a habitable world, NASA selected the Dragonfly space mission to be launched in 2027 to Titan's surface and explore the Shangri-La surface region for minimum 3 years. One of the main goals of this mission will be to understand the past and actual abundant prebiotic chemistry on Titan, especially using the Dragonfly Mass Spectrometer (DraMS). Two recently used sample pre-treatments for Gas Chromatography - Mass Spectrometry (GC-MS mode of DraMS) analyses are planned prior analysis to extract refractory organic molecules of interest for prebiotic chemistry and astrobiology. The dimethylformamide dimethylacetal (DMF-DMA) derivatization reaction offers undoubtedly an opportunity to detect biosignatures by volatilizing refractory biological or prebiotic molecules and conserving the chiral carbons' conformation while an enantiomeric excess indicates a chemical feature induced primarily by life (and may be aided on the primitive systems by light polarization). The goal of this study is to investigate the ageing of DMF-DMA in DraMS (and likely MOMA) capsules prior to in situ analysis on Titan (or Mars). The main results highlighted by our work on DMF-DMA are first its satisfactory stability for space requirements through time (no significant degradation over a year of storage and less than 30 % of lost under thermal stress) to a wide range of temperature (0 °C to 250 °C), or the presence of water and oxidants during the derivatization reaction (between 0 and 10 % of DMF-DMA degradation). Moreover, this reagent derivatized very well amines and carboxylic acids in high or trace amounts (ppt to hundreds of ppm), conserving their molecular conformation during the heat at 145 °C for 3 min (0 to 4% in the enantiomeric form change).
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Affiliation(s)
- D Boulesteix
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 rue Joliot-Curie, Gif-sur-Yvette 91190, France.
| | - A Buch
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 rue Joliot-Curie, Gif-sur-Yvette 91190, France.
| | - J Samson
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, Guyancourt 78280, France
| | - C Freissinet
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, Guyancourt 78280, France
| | - D Coscia
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, Guyancourt 78280, France
| | - Y He
- Laboratoire Génie des Procédés et Matériaux, CentraleSupélec, University Paris-Saclay, 8-10 rue Joliot-Curie, Gif-sur-Yvette 91190, France
| | - S Teinturier
- Space Science Exploration Division (Code 690), NASA, Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - J C Stern
- Space Science Exploration Division (Code 690), NASA, Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - M G Trainer
- Space Science Exploration Division (Code 690), NASA, Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - C Szopa
- LATMOS/IPSL, UVSQ University Paris-Saclay, Sorbonne University, CNRS, 11 Bd d'Alembert, Guyancourt 78280, France
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Malas J, Russo DC, Bollengier O, Malaska MJ, Lopes RMC, Kenig F, Meyer-Dombard DR. Biological functions at high pressure: transcriptome response of Shewanella oneidensis MR-1 to hydrostatic pressure relevant to Titan and other icy ocean worlds. Front Microbiol 2024; 15:1293928. [PMID: 38414766 PMCID: PMC10896736 DOI: 10.3389/fmicb.2024.1293928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 01/25/2024] [Indexed: 02/29/2024] Open
Abstract
High hydrostatic pressure (HHP) is a key driver of life's evolution and diversification on Earth. Icy moons such as Titan, Europa, and Enceladus harbor potentially habitable high-pressure environments within their subsurface oceans. Titan, in particular, is modeled to have subsurface ocean pressures ≥ 150 MPa, which are above the highest pressures known to support life on Earth in natural ecosystems. Piezophiles are organisms that grow optimally at pressures higher than atmospheric (0.1 MPa) pressure and have specialized adaptations to the physical constraints of high-pressure environments - up to ~110 MPa at Challenger Deep, the highest pressure deep-sea habitat explored. While non-piezophilic microorganisms have been shown to survive short exposures at Titan relevant pressures, the mechanisms of their survival under such conditions remain largely unelucidated. To better understand these mechanisms, we have conducted a study of gene expression for Shewanella oneidensis MR-1 using a high-pressure experimental culturing system. MR-1 was subjected to short-term (15 min) and long-term (2 h) HHP of 158 MPa, a value consistent with pressures expected near the top of Titan's subsurface ocean. We show that MR-1 is metabolically active in situ at HHP and is capable of viable growth following 2 h exposure to 158 MPa, with minimal pressure training beforehand. We further find that MR-1 regulates 264 genes in response to short-term HHP, the majority of which are upregulated. Adaptations include upregulation of the genes argA, argB, argC, and argF involved in arginine biosynthesis and regulation of genes involved in membrane reconfiguration. MR-1 also utilizes stress response adaptations common to other environmental extremes such as genes encoding for the cold-shock protein CspG and antioxidant defense related genes. This study suggests Titan's ocean pressures may not limit life, as microorganisms could employ adaptations akin to those demonstrated by terrestrial organisms.
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Affiliation(s)
- Judy Malas
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - Daniel C. Russo
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - Olivier Bollengier
- Nantes Université, Univ Angers, Le Mans Université, CNRS, Laboratoire de Planétologie et Géosciences, LPG UMR 6112, Nantes, France
| | - Michael J. Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Rosaly M. C. Lopes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Fabien Kenig
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
| | - D'Arcy R. Meyer-Dombard
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL, United States
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Richardson V, Polášek M, Romanzin C, Tosi P, Thissen R, Alcaraz C, Žabka J, Ascenzi D. Reactivity of the Ethenium Cation (C 2H 5+) with Ethyne (C 2H 2): A Combined Experimental and Theoretical Study. Molecules 2024; 29:810. [PMID: 38398562 PMCID: PMC10892252 DOI: 10.3390/molecules29040810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
The gas-phase reaction between the ethyl cation (C2H5+) and ethyne (C2H2) is re-investigated by measuring absolute reactive cross sections (CSs) and branching ratios (BRs) as a function of collision energy, in the thermal and hyperthermal energy range, via tandem-guided ion beam mass spectrometry under single collision conditions. Dissociative photoionization of C2H5Br using tuneable VUV radiation in the range 10.5-14.0 eV is employed to generate C2H5+, which has also allowed us to explore the impact of increasing (vibrational) excitation on the reactivity. Reactivity experiments are complemented by theoretical calculations, at the G4 level of theory, of the relative energies and structures of the most relevant stationary points on the reactive potential energy hypersurface (PES) and by mass-analyzed ion kinetic energy (MIKE) spectrometry experiments to probe the metastable decomposition from the [C4H7]+ PES and elucidate the underlying reaction mechanisms. Two main product channels have been identified at a centre-of-mass collision energy of ∼0.1 eV: (a) C3H3++CH4, with BR = 0.76±0.05 and (b) C4H5++H2, with BR = 0.22±0.02. A third channel giving C2H3+ in association with C2H4 is shown to emerge at both high internal excitation of C2H5+ and high collision energies. From CS measurements, energy-dependent total rate constants in the range 4.3×10-11-5.2×10-10 cm3·molecule-1·s-1 have been obtained. Theoretical calculations indicate that both channels stem from a common covalently bound intermediate, CH3CH2CHCH+, from which barrierless and exothermic pathways exist for the production of both cyclic c-C3H3+ and linear H2CCCH+ isomers of the main product channel. For the minor C4H5+ product, two isomers are energetically accessible: the three-member cyclic isomer c-C3H2(CH3)+ and the higher energy linear structure CH2CHCCH2+, but their formation requires multiple isomerization steps and passages via transition states lying only 0.11 eV below the reagents' energy, thus explaining the smaller BR. Results have implications for the modeling of hydrocarbon chemistry in the interstellar medium and the atmospheres of planets and satellites as well as in laboratory plasmas (e.g., plasma-enhanced chemical vapor deposition of carbon nanotubes and diamond-like carbon films).
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Affiliation(s)
- Vincent Richardson
- Department of Physics, University of Trento, 38123 Trento, Italy; (V.R.); (P.T.)
- Department of Physics, University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK
| | - Miroslav Polášek
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejšškova 2155/3, 182 23 Prague, Czech Republic; (M.P.); (J.Ž.)
| | - Claire Romanzin
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France; (C.R.); (R.T.); (C.A.)
- Synchrotron Soleil, L’Orme des Merisiers, 91190 Saint-Aubin, France
| | - Paolo Tosi
- Department of Physics, University of Trento, 38123 Trento, Italy; (V.R.); (P.T.)
| | - Roland Thissen
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France; (C.R.); (R.T.); (C.A.)
- Synchrotron Soleil, L’Orme des Merisiers, 91190 Saint-Aubin, France
| | - Christian Alcaraz
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France; (C.R.); (R.T.); (C.A.)
- Synchrotron Soleil, L’Orme des Merisiers, 91190 Saint-Aubin, France
| | - Ján Žabka
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejšškova 2155/3, 182 23 Prague, Czech Republic; (M.P.); (J.Ž.)
| | - Daniela Ascenzi
- Department of Physics, University of Trento, 38123 Trento, Italy; (V.R.); (P.T.)
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Neish C, Malaska MJ, Sotin C, Lopes RMC, Nixon CA, Affholder A, Chatain A, Cockell C, Farnsworth KK, Higgins PM, Miller KE, Soderlund KM. Organic Input to Titan's Subsurface Ocean Through Impact Cratering. Astrobiology 2024; 24:177-189. [PMID: 38306187 DOI: 10.1089/ast.2023.0055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
Titan has an organic-rich atmosphere and surface with a subsurface liquid water ocean that may represent a habitable environment. In this work, we determined the amount of organic material that can be delivered from Titan's surface to its ocean through impact cratering. We assumed that Titan's craters produce impact melt deposits composed of liquid water that can founder in its lower-density ice crust and estimated the amount of organic molecules that could be incorporated into these melt lenses. We used known yields for HCN and Titan haze hydrolysis to determine the amount of glycine produced in the melt lenses and found a range of possible flux rates of glycine from the surface to the subsurface ocean. These ranged from 0 to 1011 mol/Gyr for HCN hydrolysis and from 0 to 1014 mol/Gyr for haze hydrolysis. These fluxes suggest an upper limit for biomass productivity of ∼103 kgC/year from a glycine fermentation metabolism. This upper limit is significantly less than recent estimates of the hypothetical biomass production supported by Enceladus's subsurface ocean. Unless biologically available compounds can be sourced from Titan's interior, or be delivered from the surface by other mechanisms, our calculations suggest that even the most organic-rich ocean world in the Solar System may not be able to support a large biosphere.
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Affiliation(s)
- Catherine Neish
- Department of Earth Sciences, The University of Western Ontario, London, Ontario, Canada
| | - Michael J Malaska
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Christophe Sotin
- Laboratoire de Planétologie et Géosciences, Nantes Université, Univ Angers, Le Mans Université, CNRS, UMR 6112, Nantes, France
| | - Rosaly M C Lopes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Conor A Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Antonin Affholder
- Department of Ecology and Evolutionary Biology, The University of Arizona, Tucson, Arizona, USA
| | - Audrey Chatain
- Departamento de Física Aplicada, Escuela de Ingeniería de Bilbao, Universidad del País Vasco/Euskal Herriko Unibertsitatea (UPV/EHU), Bilbao, Spain
| | - Charles Cockell
- UK Centre for Astrobiology, School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Kendra K Farnsworth
- NASA Postdoctoral Program Fellow, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Peter M Higgins
- Department of Earth Sciences, University of Toronto, Toronto, Ontario, Canada
| | | | - Krista M Soderlund
- Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
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Hazen RM, Burns PC, Cleaves HJ, Downs RT, Krivovichev SV, Wong ML. Molecular assembly indices of mineral heteropolyanions: some abiotic molecules are as complex as large biomolecules. J R Soc Interface 2024; 21:20230632. [PMID: 38378136 PMCID: PMC10878807 DOI: 10.1098/rsif.2023.0632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 01/24/2024] [Indexed: 02/22/2024] Open
Abstract
Molecular assembly indices, which measure the number of unique sequential steps theoretically required to construct a three-dimensional molecule from its constituent atomic bonds, have been proposed as potential biosignatures. A central hypothesis of assembly theory is that any molecule with an assembly index ≥15 found in significant local concentrations represents an unambiguous sign of life. We show that abiotic molecule-like heteropolyanions, which assemble in aqueous solution as precursors to some mineral crystals, range in molecular assembly indices from 2 for H2CO3 or Si(OH)4 groups to as large as 21 for the most complex known molecule-like subunits in the rare minerals ewingite and ilmajokite. Therefore, values of molecular assembly indices ≥15 do not represent unambiguous biosignatures.
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Affiliation(s)
- Robert M. Hazen
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
| | - Peter C. Burns
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - H. James Cleaves
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
- Earth Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan
- Blue Marble Space Institute for Science, Seattle, WA 98104, USA
- Department of Chemistry, Howard University, Washington, DC 20059, USA
| | - Robert T. Downs
- Geological Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Sergey V. Krivovichev
- Department of Crystallography, Institute of Earth Sciences, St. Petersburg State University, St. Petersburg 199034, Russia
- Nanomaterials Research Centre, Kola Science Centre, Russian Academy of Sciences, Fersmma 14, Apatity 184209, Russia
| | - Michael L. Wong
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
- Sagan Fellow, NASA Hubble Fellowship Program, Space Telescope Science Institute, Baltimore, MD 21218, USA
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Wong ML, Cleland CE, Arend D, Bartlett S, Cleaves HJ, Demarest H, Prabhu A, Lunine JI, Hazen RM. On the roles of function and selection in evolving systems. Proc Natl Acad Sci U S A 2023; 120:e2310223120. [PMID: 37844243 PMCID: PMC10614609 DOI: 10.1073/pnas.2310223120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 09/10/2023] [Indexed: 10/18/2023] Open
Abstract
Physical laws-such as the laws of motion, gravity, electromagnetism, and thermodynamics-codify the general behavior of varied macroscopic natural systems across space and time. We propose that an additional, hitherto-unarticulated law is required to characterize familiar macroscopic phenomena of our complex, evolving universe. An important feature of the classical laws of physics is the conceptual equivalence of specific characteristics shared by an extensive, seemingly diverse body of natural phenomena. Identifying potential equivalencies among disparate phenomena-for example, falling apples and orbiting moons or hot objects and compressed springs-has been instrumental in advancing the scientific understanding of our world through the articulation of laws of nature. A pervasive wonder of the natural world is the evolution of varied systems, including stars, minerals, atmospheres, and life. These evolving systems appear to be conceptually equivalent in that they display three notable attributes: 1) They form from numerous components that have the potential to adopt combinatorially vast numbers of different configurations; 2) processes exist that generate numerous different configurations; and 3) configurations are preferentially selected based on function. We identify universal concepts of selection-static persistence, dynamic persistence, and novelty generation-that underpin function and drive systems to evolve through the exchange of information between the environment and the system. Accordingly, we propose a "law of increasing functional information": The functional information of a system will increase (i.e., the system will evolve) if many different configurations of the system undergo selection for one or more functions.
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Affiliation(s)
- Michael L. Wong
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
- Sagan Fellow, NASA Hubble Fellowship Program, Space Telescope Science Institute, Baltimore, MD21218
| | - Carol E. Cleland
- Department of Philosophy, University of Colorado, Boulder, CO80309
| | - Daniel Arend
- Department of Philosophy, University of Colorado, Boulder, CO80309
| | - Stuart Bartlett
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA91125
| | - H. James Cleaves
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
- Earth Life Science Institute, Tokyo Institute of Technology, Tokyo152-8550, Japan
- Blue Marble Space Institute for Science, Seattle, WA98104
| | - Heather Demarest
- Department of Philosophy, University of Colorado, Boulder, CO80309
| | - Anirudh Prabhu
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
| | | | - Robert M. Hazen
- Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC20015
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Birch SPD, Parker G, Corlies P, Soderblom JM, Miller JW, Palermo RV, Lora JM, Ashton AD, Hayes AG, Perron JT. Reconstructing river flows remotely on Earth, Titan, and Mars. Proc Natl Acad Sci U S A 2023; 120:e2206837120. [PMID: 37428909 PMCID: PMC10629578 DOI: 10.1073/pnas.2206837120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 06/05/2023] [Indexed: 07/12/2023] Open
Abstract
Alluvial rivers are conveyor belts of fluid and sediment that provide a record of upstream climate and erosion on Earth, Titan, and Mars. However, many of Earth's rivers remain unsurveyed, Titan's rivers are not well resolved by current spacecraft data, and Mars' rivers are no longer active, hindering reconstructions of planetary surface conditions. To overcome these problems, we use dimensionless hydraulic geometry relations-scaling laws that relate river channel dimensions to flow and sediment transport rates-to calculate in-channel conditions using only remote sensing measurements of channel width and slope. On Earth, this offers a way to predict flow and sediment flux in rivers that lack field measurements and shows that the distinct dynamics of bedload-dominated, suspended load-dominated, and bedrock rivers give rise to distinct channel characteristics. On Mars, this approach not only predicts grain sizes at Gale Crater and Jezero Crater that overlap with those measured by the Curiosity and Perseverance rovers, it enables reconstructions of past flow conditions that are consistent with proposed long-lived hydrologic activity at both craters. On Titan, our predicted sediment fluxes to the coast of Ontario Lacus could build the lake's river delta in as little as ~1,000 y, and our scaling relationships suggest that Titan's rivers may be wider, slope more gently, and transport sediment at lower flows than rivers on Earth or Mars. Our approach provides a template for predicting channel properties remotely for alluvial rivers across Earth, along with interpreting spacecraft observations of rivers on Titan and Mars.
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Affiliation(s)
- Samuel P. D. Birch
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Gary Parker
- Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL61820
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL61820
| | - Paul Corlies
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Jason M. Soderblom
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Julia W. Miller
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA90095
| | - Rose V. Palermo
- Massachusetts Institute of Technology-Woods Hole Oceanographic Institute Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge and Woods Hole, MA02139
| | - Juan M. Lora
- Department of Earth and Planetary Sciences, Yale University, New Haven, CT06520
| | - Andrew D. Ashton
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA02543
| | | | - J. Taylor Perron
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA02139
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Moulay V, Freissinet C, Rizk-Bigourd M, Buch A, Ancelin M, Couturier E, Breton C, Trainer MG, Szopa C. Selection and Analytical Performances of the Dragonfly Mass Spectrometer Gas Chromatographic Columns to Support the Search for Organic Molecules of Astrobiological Interest on Titan. Astrobiology 2023; 23:213-229. [PMID: 36577024 DOI: 10.1089/ast.2022.0038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Titan is a key planetary body for astrobiology, with the presence of a subsurface ocean and a dense atmosphere, in which complex chemistry is known to occur. Approximately 1-Titan-year after the Cassini-Huygens mission arrived in the saturnian system, Dragonfly rotorcraft will land on Titan's surface by 2034 for an exhaustive geophysical and chemical investigation of the Shangri-La organic sand sea region. Among the four instruments onboard Dragonfly, the Dragonfly Mass Spectrometer (DraMS) is dedicated to analyze the chemical composition of surface samples and noble gases in the atmosphere. One of the DraMS analysis modes, the Gas Chromatograph-Mass Spectrometer (GC-MS), is devoted to the detection and identification of organic molecules that could be involved in the development of a prebiotic chemistry or even representative of traces of past or present life. Therefore, DraMS-GC subsystem should be optimized to detect and identify relevant organic compounds to meet this objective. This work is focused on the experimental methods employed to select the chromatographic column to be integrated in DraMS-GC, to assess the analytical performances of the column selected, and also to assess the performances of the second DraMS-GC column, which is devoted to the separation of organic enantiomers. Four different stationary phases have been tested to select the most relevant one for the separation of the targeted chemical species. The results show that the stationary phase composed of polymethyl (95%) diphenyl (5%) siloxane is the best compromise in terms of efficiency, robustness, and retention times of the molecules. The combination of the general and the chiral columns in DraMS is perfectly suited to in situ chemical analysis on Titan and for the detection of expected diverse and complex organic compounds.
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Affiliation(s)
- Valentin Moulay
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Caroline Freissinet
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Malak Rizk-Bigourd
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Arnaud Buch
- Laboratoire Génie des Procédés et Matériaux, CentraleSupelec, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Mayline Ancelin
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Elise Couturier
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Caroline Breton
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
| | - Melissa G Trainer
- Solar System Exploration Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Cyril Szopa
- LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
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10
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Lapôtre MGA, Malaska MJ, Cable ML. The Role of Seasonal Sediment Transport and Sintering in Shaping Titan's Landscapes: A Hypothesis. Geophys Res Lett 2022; 49:e2021GL097605. [PMID: 35860461 PMCID: PMC9285677 DOI: 10.1029/2021gl097605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 06/15/2023]
Abstract
Titan is a sedimentary world, with lakes, rivers, canyons, fans, dissected plateaux, and sand dunes. Sediments on Saturn's moon are thought to largely consist of mechanically weak organic grains, prone to rapid abrasion into dust. Yet, Titan's equatorial dunes have likely been active for 10s-100s kyr. Sustaining Titan's dunes over geologic timescales requires a mechanism that produces sand-sized particles at equatorial latitudes. We explore the hypothesis that a combination of abrasion, when grains are transported by winds or methane rivers, and sintering, when they are at rest, could produce sand grains that maintain an equilibrium size. Our model demonstrates that seasonal sediment transport may produce sand under Titan's surface conditions and could explain the latitudinal zonation of Titan's landscapes. Our findings support the hypothesis of global, source-to-sink sedimentary pathways on Titan, driven by seasons, and mediated by episodic abrasion and sintering of organic sand by rivers and winds.
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Affiliation(s)
| | - Michael J. Malaska
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - Morgan L. Cable
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
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11
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Maue AD, Levy JS, Burr DM, Matulka PR, Nathan E. Sieved mass and shape data from simulated fluvial transport of icy clasts in the Titan Tumbler. Data Brief 2022; 40:107815. [PMID: 35141365 PMCID: PMC8813593 DOI: 10.1016/j.dib.2022.107815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 11/24/2022] Open
Abstract
Data in this article are related to the research article “Rapid rounding of icy clasts during simulated fluvial transport in the Titan Tumbler”. Whereas that research focused on low-temperature ice abrasion in the context of Saturn's moon Titan, the full dataset on experiments testing the breakdown of water ice under a variety of tested conditions is reported in this article. Following the work of previous terrestrial studies, these experiments utilize tumblers that produce collisions to simulate some aspects of mechanical weathering during fluvial transport. Data files publicly available on Mendeley Data include measures of mass and roundness of clasts of specific grain sizes as well as raw images, videos, and the MATLAB script used for analysis. In this article, the varying conditions of temperature, initial clast size, shape, ice type, number of clasts for each of the 42 experiments are reported, along with best-fit models of abrasion typically applied in terrestrial tumbler studies. This text describes the methodology, including the development of icy clasts, operation of the tumblers, measurement of clast properties, calculation of derived parameters, and application of abrasion models. Exploration of various approaches to tumbler development and data acquisition are reported to benefit future researchers in this area. Experiments on the abrasion of different materials benefit from cross-comparison, which is also a fundamental aspect of planetary science.
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Affiliation(s)
- Anthony D Maue
- Department of Astronomy and Planetary Science, Northern Arizona University, 527 S. Beaver St., Flagstaff, AZ 86011, United States
| | - Joseph S Levy
- Department of Geology, Colgate University, 13 Oak Drive, Hamilton, NY 13346, United States
| | - Devon M Burr
- Department of Astronomy and Planetary Science, Northern Arizona University, 527 S. Beaver St., Flagstaff, AZ 86011, United States
| | - Patrick R Matulka
- Department of Earth and Planetary Sciences, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, United States
| | - Erica Nathan
- Department of Earth, Environmental and Planetary Sciences, Brown University, Box 1846, 324 Brook Street, Providence, RI 02912, United States
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12
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Rafkin S, Lora JM, Soto A, Battalio J. The interaction of deep convection with the general circulation in Titan's atmosphere. Part 1: Cloud Resolving Simulations. Icarus 2022; 373:114623. [PMID: 34916708 PMCID: PMC8670393 DOI: 10.1016/j.icarus.2021.114755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The deep convective cloud-environment feedback loop is likely important to Titan's global methane, energy, and momentum cycles, just as it is for Earth's global water, energy, and momentum budgets. General circulation models of Titan's atmosphere are unable to explicitly simulate deep convection and must instead parameterize the impact of this important subgrid-scale phenomenon on the model-resolved atmospheric state. The goal of this study is to better quantify through cloud resolving modeling the effects of deep convective methane storms on their environment and to feed that information forward to improve parameterizations in global models. Dozens of atmospheric profiles unstable with respect to deep moist convection are extracted from the global Titan Atmospheric Model (TAM) and used to initialize the cloud-resolving Titan Regional Atmospheric Modeling System (TRAMS). Mean profiles of heating/cooling and moistening/drying of the large-scale environment in TRAMS indicate that Titan's deep convection forces the environment in a manner analogous to Earth: Large-scale subsidence of the environmental air warms and dries the environment, but clouds can also moisten the environment through the detrainment and evaporation of condensate near cloud top. Relative humidity profiles and characteristic convective time scales are derived to guide the tuning of the deep convective parameterization implemented in TAM, as described in a companion paper. The triggering of convection, the dry convective mixing of the planetary boundary layer, and the entrainment of environmental air into rising air parcels are found to be critical to determining whether a deep convective cloud will form. Only profiles with relatively large convective available potential energy (CAPE) and well mixed planetary boundary layers with high relative humidity were found to produce storms. Environments with low level thermal inversions and planetary boundary layers with low relative humidity or rapidly decreasing moisture with height failed to generate deep convection in TRAMS despite positive CAPE.
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Affiliation(s)
- S. Rafkin
- Southwest Research Institute, Department of Space Studies, Boulder, CO
| | - J. M. Lora
- Yale University, Department of Earth and Planetary Sciences, New Haven, CT
| | - A. Soto
- Southwest Research Institute, Department of Space Studies, Boulder, CO
| | - J. Battalio
- Yale University, Department of Earth and Planetary Sciences, New Haven, CT
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13
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Abstract
The emerging understanding of microbial trace gas chemotrophy as a metabolic strategy to support energy and carbon acquisition for microbial survival and growth has significant implications in the search for past, and even extant, life beyond Earth. The use of trace gases, including hydrogen and carbon monoxide as substrates for microbial oxidation, potentially offers a viable strategy with which to support life on planetary bodies that possess a suitable atmospheric composition, such as Mars and Titan. Here, we discuss the current state of knowledge of this process and explore its potential in the field of astrobiological exploration.
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Affiliation(s)
- Don A. Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Address correspondence to: Don A. Cowan, Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Building NW2, Room 3-12, Hatfield Campus, Lynnwood Road, Pretoria 0002, South Africa
| | - Belinda C. Ferrari
- School of Biotechnology and Biomolecular Sciences, Australian Centre for Astrobiology, UNSW Sydney, Randwick, Australia
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14
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Battalio JM, Lora JM, Rafkin S, Soto A. The interaction of deep convection with the general circulation in Titan's atmosphere. Part 2: Impacts on the climate. Icarus 2022; 373:114623. [PMID: 34916707 PMCID: PMC8670386 DOI: 10.1016/j.icarus.2021.114623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The impact of methane convection on the circulation of Titan is investigated in the Titan Atmospheric Model (TAM), using a simplified Betts-Miller (SBM) moist convection parameterization scheme. We vary the reference relative humidity (RHSBM ) and relaxation timescale of convection (τ) parameters of the SBM scheme. Titan's atmosphere is mostly insensitive to changes in τ, but convective instability and precipitation are highly impacted by changes in RHSBM . Convection changes behavior from occurring in infrequent (<1 per Titan year), intense events at summer solstice that quickly encompass the entire globe at low RHSBM to near-continuous precipitation at the poles during summer at high RHSBM (>85%). The intermediate regime (RHSBM =70-80%) consists of frequent events (~10 per Titan year) of moderate intensity that are limited in meridional extent to their respective hemisphere. Using results from the Titan Regional Atmospheric Modeling System (TRAMS) and observations, we tune the parameters of the SBM parameterization with optimum values of RH=80% and τ=28800 s. We present a simulated decadal climatology that qualitatively matches observations of Titan's humidity and cloud activity and generally resembles previous results with TAM. Comparing this simulation to one without moist convection demonstrates that convection strengthens the meridional circulation, warms the mid-levels and cools the surface at the poles, and magnifies zonal-mean global moisture anomalies.
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Affiliation(s)
- J Michael Battalio
- Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511
| | - Juan M Lora
- Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511
| | - Scot Rafkin
- Department of Space Studies, Southwest Research Institute, 1050 Walnut St, Suite 300, Boulder, Colorado, USA 80302
| | - Alejandro Soto
- Department of Space Studies, Southwest Research Institute, 1050 Walnut St, Suite 300, Boulder, Colorado, USA 80302
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15
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Freindorf M, Beiranvand N, Delgado AAA, Tao Y, Kraka E. On the formation of CN bonds in Titan's atmosphere-a unified reaction valley approach study. J Mol Model 2021; 27:320. [PMID: 34633543 DOI: 10.1007/s00894-021-04917-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/15/2021] [Indexed: 08/30/2023]
Abstract
In this work, we investigated the formation of protonated hydrogen cyanide HCNH+ and methylene amine cation CH[Formula: see text] (both identified in Titan's upper atmosphere) from three different pathways which stem from the interaction between CH4 and N+(3P). As a mechanistic tool, we used the Unified Reaction Valley Approach (URVA) complemented with the Local Mode Analysis (LMA) assessing the strength of the CN bonds formed in these reactions. Our URVA studies could provide a comprehensive overview on bond formation/cleavage processes relevant to the specific mechanism of eight reactions R1- R8 that occur across the three pathways. In addition, we could explain the formation of CH[Formula: see text] and the appearance of HCNH+ and CHNH[Formula: see text] along these paths. Although only smaller molecules are involved in these reactions including isomerization, hydrogen atom abstraction, and hydrogen molecule capture, we found a number of interesting features, such as roaming in reaction R3 or the primary interaction of H2 with the carbon atom in HCNH+ in reaction R8 followed by migration of one of the H2 hydrogen atoms to the nitrogen which is more cost effective than breaking the HH bond first; a feature often found in catalysis. In all cases, charge transfer between carbon and nitrogen could be identified as a driving force for the CN bond formation. As revealed by LMA, the CN bonds formed in reactions R1-R8 cover a broad bond strength range from very weak to very strong, with the CN bond in protonated hydrogen cyanide HCNH+ identified as the strongest of all molecules investigated in this work. Our study demonstrates the large potential of both URVA and LMA to shed new light into these extraterrestrial reactions to help better understand prebiotic processes as well as develop guidelines for future investigations involving areas of complex interstellar chemistry. In particular, the formation of CN bonds as a precursor to the extraterrestrial formation of amino acids will be the focus of future investigations. Formation of CN bonds in Titan's atmosphere visualized via the reaction path curvature.
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Affiliation(s)
- Marek Freindorf
- Chemistry Department, SMU, Fondren Science Building, Dallas, 75275-0314, TX, USA
| | - Nassim Beiranvand
- Chemistry Department, SMU, Fondren Science Building, Dallas, 75275-0314, TX, USA
| | - Alexis A A Delgado
- Chemistry Department, SMU, Fondren Science Building, Dallas, 75275-0314, TX, USA
| | - Yunwen Tao
- Chemistry Department, SMU, Fondren Science Building, Dallas, 75275-0314, TX, USA
| | - Elfi Kraka
- Chemistry Department, SMU, Fondren Science Building, Dallas, 75275-0314, TX, USA.
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16
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Oremland RS. Got acetylene: a personal research retrospective. FEMS Microbes 2021; 2:xtab009. [PMID: 37334230 PMCID: PMC10117869 DOI: 10.1093/femsmc/xtab009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/28/2021] [Indexed: 07/20/2023] Open
Abstract
In research, sometimes sheer happenstance and serendipity make for an unexpected discovery. Once revealed and if interesting enough, such a finding and its follow-up investigations can lead to advances by others that leave its originators 'scooped' and mulling about what next to do with their unpublished data, specifically what journals could it still be published in and be perceived as original. This is what occurred with us nearly 40 years ago with regard to our follow-up observations of acetylene fermentation and led us to concoct a 'cock-and-bull' story. We hypothesized about a plausible role for acetylene metabolism in the primordial biogeochemistry of Earth and the possibility of acetylene serving as a key life-sustaining substrate for alien microbes dwelling in the orbs of the outer solar system. With the passage of time, advances were made in whole-genome sequencing coupled with major in silico progress in bioinformatics. In parallel came the results of explorations of the outer solar system (i.e. the Cassini mission to Saturn and its moons). It now appears that these somewhat harebrained ideas of ours, arisen at first out of a sense of desperation, actually ring true in fact, and particularly well in song: 'Tell a tale of cock and bull, Of convincing detail full Tale tremendous, Heav'n defend us! What a tale of cock and bull!' From 'The Yeoman of the Guard' by Gilbert & Sullivan.
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Affiliation(s)
- Ronald S Oremland
- Corresponding author: US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA. E-mail:
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17
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Jaramillo-Botero A, Cable ML, Hofmann AE, Malaska M, Hodyss R, Lunine J. Understanding Hypervelocity Sampling of Biosignatures in Space Missions. Astrobiology 2021; 21:421-442. [PMID: 33749334 PMCID: PMC7994429 DOI: 10.1089/ast.2020.2301] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/09/2020] [Indexed: 05/08/2023]
Abstract
The atomic-scale fragmentation processes involved in molecules undergoing hypervelocity impacts (HVIs; defined as >3 km/s) are challenging to investigate via experiments and still not well understood. This is particularly relevant for the consistency of biosignals from small-molecular-weight neutral organic molecules obtained during solar system robotic missions sampling atmospheres and plumes at hypervelocities. Experimental measurements to replicate HVI effects on neutral molecules are challenging, both in terms of accelerating uncharged species and isolating the multiple transition states over very rapid timescales (<1 ps). Nonequilibrium first-principles-based simulations extend the range of what is possible with experiments. We report on high-fidelity simulations of the fragmentation of small organic biosignature molecules over the range v = 1-12 km/s, and demonstrate that the fragmentation fraction is a sensitive function of velocity, impact angle, molecular structure, impact surface material, and the presence of surrounding ice shells. Furthermore, we generate interpretable fragmentation pathways and spectra for velocity values above the fragmentation thresholds and reveal how organic molecules encased in ice grains, as would likely be the case for those in "ocean worlds," are preserved at even higher velocities than bare molecules. Our results place ideal spacecraft encounter velocities between 3 and 5 km/s for bare amino and fatty acids and within 4-6 km/s for the same species encased in ice grains and predict the onset of organic fragmentation in ice grains at >5 km/s, both consistent with recent experiments exploring HVI effects using impact-induced ionization and analysis via mass spectrometry and from the analysis of Enceladus organics in Cassini Data. From nanometer-sized ice Ih clusters, we establish that HVI energy is dissipated by ice casings through thermal resistance to the impact shock wave and that an upper fragmentation velocity limit exists at which ultimately any organic contents will be cleaved by the surrounding ice-this provides a fundamental path to characterize micrometer-sized ice grains. Altogether, these results provide quantifiable insights to bracket future instrument design and mission parameters.
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Affiliation(s)
- Andres Jaramillo-Botero
- Chemistry and Chemical Engineering Division, California Institute of Technology, Pasadena, California, USA
| | - Morgan L. Cable
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Amy E. Hofmann
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Michael Malaska
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Robert Hodyss
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Jonathan Lunine
- Department of Astronomy and Carl Sagan Institute, Cornell University, Ithaca, New York, USA
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18
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Abstract
"The new frontier of robotic surgery is well under way. Current research and development is rapidly progressing, allowing for the creation of many new robotic companies. Each company has its own identity and platform for what their vision for the future entails. The competition generated between these companies will shortly be forcing newer, cheaper, more accessible robotic systems worldwide."
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19
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Longo A, Damer B. Factoring Origin of Life Hypotheses into the Search for Life in the Solar System and Beyond. Life (Basel) 2020; 10:E52. [PMID: 32349245 PMCID: PMC7281141 DOI: 10.3390/life10050052] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/14/2020] [Accepted: 04/22/2020] [Indexed: 01/13/2023] Open
Abstract
Two widely-cited alternative hypotheses propose geological localities and biochemical mechanisms for life's origins. The first states that chemical energy available in submarine hydrothermal vents supported the formation of organic compounds and initiated primitive metabolic pathways which became incorporated in the earliest cells; the second proposes that protocells self-assembled from exogenous and geothermally-delivered monomers in freshwater hot springs. These alternative hypotheses are relevant to the fossil record of early life on Earth, and can be factored into the search for life elsewhere in the Solar System. This review summarizes the evidence supporting and challenging these hypotheses, and considers their implications for the search for life on various habitable worlds. It will discuss the relative probability that life could have emerged in environments on early Mars, on the icy moons of Jupiter and Saturn, and also the degree to which prebiotic chemistry could have advanced on Titan. These environments will be compared to ancient and modern terrestrial analogs to assess their habitability and biopreservation potential. Origins of life approaches can guide the biosignature detection strategies of the next generation of planetary science missions, which could in turn advance one or both of the leading alternative abiogenesis hypotheses.
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Affiliation(s)
- Alex Longo
- National Aeronautics and Space Administration Headquarters, Washington, DC 20546, USA
- Department of Geology, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Bruce Damer
- Department of Biomolecular Engineering, University of California, Santa Cruz, CA 95064, USA or
- Digital Space Research, Boulder Creek, CA 95006, USA
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20
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Martin KP, MacKenzie SM, Barnes JW, Ytreberg FM. Protein Stability in Titan's Subsurface Water Ocean. Astrobiology 2020; 20:190-198. [PMID: 31730377 PMCID: PMC7041334 DOI: 10.1089/ast.2018.1972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 10/08/2019] [Indexed: 06/10/2023]
Abstract
Models of Titan predict that there is a subsurface ocean of water and ammonia under a layer of ice. Such an ocean would be important in the search for extraterrestrial life since it provides a potentially habitable environment. To evaluate how Earth-based proteins would behave in Titan's subsurface ocean environment, we used molecular dynamics simulations to calculate the properties of proteins with the most common secondary structure types (alpha helix and beta sheet) in both Earth and Titan-like conditions. The Titan environment was simulated by using a temperature of 300 K, a pressure of 1000 bar, and a eutectic mixture of water and ammonia. We analyzed protein compactness, flexibility, and backbone dihedral distributions to identify differences between the two environments. Secondary structures in the Titan environment were found to be less long-lasting, less flexible, and had small differences in backbone dihedral preferences (e.g., in one instance a pi helix formed). These environment-driven differences could lead to changes in how these proteins interact with other biomolecules and therefore changes in how evolution would potentially shape proteins to function in subsurface ocean environments.
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Affiliation(s)
- Kyle P. Martin
- Department of Physics, University of Idaho, Moscow, Idaho
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho
| | | | | | - F. Marty Ytreberg
- Department of Physics, University of Idaho, Moscow, Idaho
- Institute for Modeling Collaboration and Innovation, University of Idaho, Moscow, Idaho
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21
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Brand HEA, Gu Q, Kimpton JA, Auchettl R, Ennis C. Crystal structure of propionitrile (CH 3CH 2CN) determined using synchrotron powder X-ray diffraction. J Synchrotron Radiat 2020; 27:212-216. [PMID: 31868754 DOI: 10.1107/s1600577519015911] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 11/25/2019] [Indexed: 06/10/2023]
Abstract
The structure and thermal expansion of the astronomical molecule propionitrile have been determined from 100 to 150 K using synchrotron powder X-ray diffraction. This temperature range correlates with the conditions of Titan's lower stratosphere, and near surface, where propionitrile is thought to accumulate and condense into pure and mixed-nitrile phases. Propionitrile was determined to crystallize in space group, Pnma (No. 62), with unit cell a = 7.56183 (16) Å, b = 6.59134 (14) Å, c = 7.23629 (14), volume = 360.675 (13) Å3 at 100 K. The thermal expansion was found to be highly anisotropic with an eightfold increase in expansion between the c and b axes. These data will prove crucial in the computational modelling of propionitrile-ice systems in outer Solar System environments, allowing us to simulate and assign vibrational peaks in the infrared spectra for future use in planetary astronomy.
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Affiliation(s)
- Helen E A Brand
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Qinfen Gu
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Justin A Kimpton
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Rebecca Auchettl
- Australian Synchrotron, ANSTO, 800 Blackburn Road, Clayton, Victoria 3168, Australia
| | - Courtney Ennis
- University of Otago, PO Box 56, Dunedin 9054, New Zealand
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22
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Richardson I, Hartwig J, Leachman J. Experimental Effervescence and Freezing Point Depression Measurements of Nitrogen in Liquid Methane-Ethane Mixtures. Int J Therm Sci 2019; 137:534-538. [PMID: 32021553 PMCID: PMC6999730 DOI: 10.1016/j.ijthermalsci.2018.12.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
NASA is designing an unmanned submarine to explore the depths of the hydrocarbon-rich seas on Saturn's moon Titan. Data from Cassini indicates that the Titan north polar environment sustains stable seas of variable concentrations of ethane, methane, and nitrogen, with a surface temperature near 93 K. The submarine must operate autonomously, study atmosphere/sea exchange, interact with the seabed, hover at the surface or any depth within the sea, and be capable of tolerating variable hydrocarbon compositions. Currently, the main thermal design concern is the effect of effervescence on submarine operation, which affects the ballast system, science instruments, and propellers. Twelve effervescence measurements on various liquid methane-ethane compositions with dissolved gaseous nitrogen are thus presented from 1.5 bar to 4.5 bar at temperatures from 92 K to 96 K to simulate the conditions of the seas. After conducting effervescence measurements, two freezing point depression measurements were conducted. The freezing liquid line was depressed more than 15 K below the triple point temperatures of pure ethane (90.4 K) and pure methane (90.7 K). Experimental effervescence measurements will be used to compare directly with effervescence modeling to determine if changes are required in the design of the thermal management system as well as the propellers.
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Affiliation(s)
- I.A. Richardson
- HYdrogen Properties for Energy Research (HYPER) Laboratory, Washington State University, Pullman, WA 99164-2920 USA
| | - J.W. Hartwig
- Cryogenic Propulsion Engineer, NASA Glenn Research Center, Cleveland, OH 44106 USA
| | - J.W. Leachman
- HYdrogen Properties for Energy Research (HYPER) Laboratory, Washington State University, Pullman, WA 99164-2920 USA
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Hendrix AR, Hurford TA, Barge LM, Bland MT, Bowman JS, Brinckerhoff W, Buratti BJ, Cable ML, Castillo-Rogez J, Collins GC, Diniega S, German CR, Hayes AG, Hoehler T, Hosseini S, Howett CJ, McEwen AS, Neish CD, Neveu M, Nordheim TA, Patterson GW, Patthoff DA, Phillips C, Rhoden A, Schmidt BE, Singer KN, Soderblom JM, Vance SD. The NASA Roadmap to Ocean Worlds. Astrobiology 2019; 19:1-27. [PMID: 30346215 PMCID: PMC6338575 DOI: 10.1089/ast.2018.1955] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 09/21/2018] [Indexed: 05/20/2023]
Abstract
In this article, we summarize the work of the NASA Outer Planets Assessment Group (OPAG) Roadmaps to Ocean Worlds (ROW) group. The aim of this group is to assemble the scientific framework that will guide the exploration of ocean worlds, and to identify and prioritize science objectives for ocean worlds over the next several decades. The overarching goal of an Ocean Worlds exploration program as defined by ROW is to "identify ocean worlds, characterize their oceans, evaluate their habitability, search for life, and ultimately understand any life we find." The ROW team supports the creation of an exploration program that studies the full spectrum of ocean worlds, that is, not just the exploration of known ocean worlds such as Europa but candidate ocean worlds such as Triton as well. The ROW team finds that the confirmed ocean worlds Enceladus, Titan, and Europa are the highest priority bodies to target in the near term to address ROW goals. Triton is the highest priority candidate ocean world to target in the near term. A major finding of this study is that, to map out a coherent Ocean Worlds Program, significant input is required from studies here on Earth; rigorous Research and Analysis studies are called for to enable some future ocean worlds missions to be thoughtfully planned and undertaken. A second finding is that progress needs to be made in the area of collaborations between Earth ocean scientists and extraterrestrial ocean scientists.
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Affiliation(s)
- Amanda R. Hendrix
- Planetary Science Institute, Tucson, Arizona
- Address correspondence to: Amanda R. Hendrix, Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719
| | | | - Laura M. Barge
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Michael T. Bland
- Astrogeology Science Center, U.S. Geological Survey, Flagstaff, Arizona
| | - Jeff S. Bowman
- Scripps Institution of Oceanography, La Jolla, California
| | | | - Bonnie J. Buratti
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Morgan L. Cable
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | - Julie Castillo-Rogez
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | | | - Serina Diniega
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | | | - Alexander G. Hayes
- Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca, New York
| | - Tori Hoehler
- NASA Ames Research Center, Mountain View, California
| | - Sona Hosseini
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | | | - Alfred S. McEwen
- Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona
| | - Catherine D. Neish
- Planetary Science Institute, Tucson, Arizona
- Department of Earth Sciences, The University of Western Ontario, London, Ontario, Canada
| | - Marc Neveu
- NASA HQ/Universities Space Association, Washington, District of Columbia
| | - Tom A. Nordheim
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | | | | | - Cynthia Phillips
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
| | | | - Britney E. Schmidt
- School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | | | - Jason M. Soderblom
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Steven D. Vance
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
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24
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Mandt K, Luspay-Kuti A, Hamel M, Jessup KL, Hue V, Kammer J, Filwett R. Photochemistry on Pluto: part II HCN and nitrogen isotope fractionation. Mon Not R Astron Soc 2017; 472:118-128. [PMID: 31105342 PMCID: PMC6525008 DOI: 10.1093/mnras/stx1587] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We have converted our Titan one-dimensional photochemical model to simulate the photo- chemistry of Pluto's atmosphere and include condensation and aerosol trapping in the model. We find that condensation and aerosol trapping are important processes in producing the HCN altitude profile observed by the Atacama Large Millimeter Array (ALMA). The nitrogen iso- tope chemistry in Pluto's atmosphere does not appear to significantly fractionate the isotope ratio between N2 and HCN as occurs at Titan. However, our simulations only cover a brief period of time in a Pluto year, and thus only a brief portion of the solar forcing conditions that Pluto's atmosphere experiences. More work is needed to evaluate photochemical fractionation over a Pluto year. Condensation and aerosol trapping appear to have a major impact on the altitude profile of the isotope ratio in HCN. Since ALMA did not detect HC15N in Pluto's atmosphere, we conclude that condensation and aerosol trapping must be much more efficient for HC15N compared to HC14N. The large uncertainty in photochemical fractionation makes it difficult to use any potential current measurement of 14N/15N in N2 to determine the origin of Pluto's nitrogen. More work is needed to understand photochemical fractionation and to evaluate how condensation, sublimation and aerosol trapping will fractionate N2 and HCN.
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Affiliation(s)
- Kathleen Mandt
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Blvd., San Antonio, TX 78249, USA
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Rd., Laurel, MD 20723, USA
| | - Adrienn Luspay-Kuti
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
| | - Mark Hamel
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Blvd., San Antonio, TX 78249, USA
| | - Kandis-Lea Jessup
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
| | - Vincent Hue
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
| | - Josh Kammer
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
| | - Rachael Filwett
- Space Science and Engineering Division, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238, USA
- Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Blvd., San Antonio, TX 78249, USA
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Abstract
OBJECTIVE Nanoparticles having a size from 1 to 100nm are present in nature and are successfully used in many products of daily life. Nanoparticles are also embedded per se or as byproducts from milling processes of larger filler particles in many dental materials. METHODS AND RESULTS Recently, possible adverse effects of nanoparticles have gained increased interest with the lungs being a main target organ. Exposure to nanoparticles in dentistry may occur in the dental laboratory, by processing gypsum type products or by grinding and polishing materials. In the dental practice virtually no exposure to nanoparticles occurs when handling unset materials. However, nanoparticles are produced by intraoral adjustment of set restorative materials through grinding/polishing regardless whether they contain nanoparticles or not. Nanoparticles may also be produced through wear of restorations or released from dental implants and they enter the environment when removing restorations. The risk for dental technicians is taken care of by legal regulations. Based on model worst case mass-based calculations, the exposure of dental practice personnel and patients to nanoparticles through intraoral grinding/polishing and wear is low to negligible. Accordingly, the additional risk due to nanoparticles exposure from present materials is considered to be low. However, more research is needed, especially on vulnerable groups (asthma or COPD). An assessment of risks for the environment is not possible due to the lack of data. SIGNIFICANCE Measures to reduce exposure to nanoparticles include intraorally grinding/polishing using water coolants, proper sculpturing to reduce the need for grinding and sufficient ventilation of treatment areas.
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Affiliation(s)
- Gottfried Schmalz
- Department of Conservative Dentistry and Periodontology, University Hospital, Regensburg, Germany
| | - Reinhard Hickel
- Department of Conservative Dentistry and Periodontology, University Hospital, LMU Munich, Germany
| | | | - Franz-Xaver Reichl
- Department of Conservative Dentistry and Periodontology, University Hospital, LMU Munich, Germany.
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Rahm M, Lunine JI, Usher DA, Shalloway D. Polymorphism and electronic structure of polyimine and its potential significance for prebiotic chemistry on Titan. Proc Natl Acad Sci U S A 2016; 113:8121-6. [PMID: 27382167 DOI: 10.1073/pnas.1606634113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The chemistry of hydrogen cyanide (HCN) is believed to be central to the origin of life question. Contradictions between Cassini-Huygens mission measurements of the atmosphere and the surface of Saturn's moon Titan suggest that HCN-based polymers may have formed on the surface from products of atmospheric chemistry. This makes Titan a valuable "natural laboratory" for exploring potential nonterrestrial forms of prebiotic chemistry. We have used theoretical calculations to investigate the chain conformations of polyimine (pI), a polymer identified as one major component of polymerized HCN in laboratory experiments. Thanks to its flexible backbone, the polymer can exist in several different polymorphs, which are relatively close in energy. The electronic and structural variability among them is extraordinary. The band gap changes over a 3-eV range when moving from a planar sheet-like structure to increasingly coiled conformations. The primary photon absorption is predicted to occur in a window of relative transparency in Titan's atmosphere, indicating that pI could be photochemically active and drive chemistry on the surface. The thermodynamics for adding and removing HCN from pI under Titan conditions suggests that such dynamics is plausible, provided that catalysis or photochemistry is available to sufficiently lower reaction barriers. We speculate that the directionality of pI's intermolecular and intramolecular =N-H(…)N hydrogen bonds may drive the formation of partially ordered structures, some of which may synergize with photon absorption and act catalytically. Future detailed studies on proposed mechanisms and the solubility and density of the polymers will aid in the design of future missions to Titan.
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Maynard-Casely HE, Hodyss R, Cable ML, Vu TH, Rahm M. A co-crystal between benzene and ethane: a potential evaporite material for Saturn's moon Titan. IUCrJ 2016; 3:192-199. [PMID: 27158505 PMCID: PMC4856141 DOI: 10.1107/s2052252516002815] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/16/2016] [Indexed: 06/01/2023]
Abstract
Using synchrotron X-ray powder diffraction, the structure of a co-crystal between benzene and ethane formed in situ at cryogenic conditions has been determined, and validated using dispersion-corrected density functional theory calculations. The structure comprises a lattice of benzene molecules hosting ethane molecules within channels. Similarity between the intermolecular interactions found in the co-crystal and in pure benzene indicate that the C-H⋯π network of benzene is maintained in the co-crystal, however, this expands to accommodate the guest ethane molecules. The co-crystal has a 3:1 benzene:ethane stoichiometry and is described in the space group [Formula: see text] with a = 15.977 (1) Å and c = 5.581 (1) Å at 90 K, with a density of 1.067 g cm(-3). The conditions under which this co-crystal forms identify it is a potential that forms from evaporation of Saturn's moon Titan's lakes, an evaporite material.
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Affiliation(s)
- Helen E. Maynard-Casely
- Bragg Institute, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Robert Hodyss
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Morgan L. Cable
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Tuan Hoang Vu
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Martin Rahm
- Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA
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28
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Abstract
Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan’s atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic—polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms.
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Affiliation(s)
- Christopher P McKay
- Space Science Division, NASA Ames Research Center, Moffett Field, CA 94035, USA.
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29
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Baker VR, Hamilton CW, Burr DM, Gulick VC, Komatsu G, Luo W, Rice JW, Rodriguez J. Fluvial geomorphology on Earth-like planetary surfaces: A review. Geomorphology (Amst) 2015; 245:149-182. [PMID: 29176917 PMCID: PMC5701759 DOI: 10.1016/j.geomorph.2015.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Morphological evidence for ancient channelized flows (fluvial and fluvial-like landforms) exists on the surfaces of all of the inner planets and on some of the satellites of the Solar System. In some cases, the relevant fluid flows are related to a planetary evolution that involves the global cycling of a volatile component (water for Earth and Mars; methane for Saturn's moon Titan). In other cases, as on Mercury, Venus, Earth's moon, and Jupiter's moon Io, the flows were of highly fluid lava. The discovery, in 1972, of what are now known to be fluvial channels and valleys on Mars sparked a major controversy over the role of water in shaping the surface of that planet. The recognition of the fluvial character of these features has opened unresolved fundamental questions about the geological history of water on Mars, including the presence of an ancient ocean and the operation of a hydrological cycle during the earliest phases of planetary history. Other fundamental questions posed by fluvial and fluvial-like features on planetary bodies include the possible erosive action of large-scale outpourings of very fluid lavas, such as those that may have produced the remarkable canali forms on Venus; the ability of exotic fluids, such as methane, to create fluvial-like landforms, as observed on Saturn's moon, Titan; and the nature of sedimentation and erosion under different conditions of planetary surface gravity. Planetary fluvial geomorphology also illustrates fundamental epistemological and methodological issues, including the role of analogy in geomorphological/geological inquiry.
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Affiliation(s)
- Victor R. Baker
- Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA
- Lunar and Planetary Laboratory, Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Christopher W. Hamilton
- Lunar and Planetary Laboratory, Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Devon M. Burr
- Earth and Planetary Sciences Department, University of Tennessee-Knoxville, Knoxville, TN 37996-1410, USA
| | - Virginia C. Gulick
- SETI Institute, Mountain View, CA 94043, USA
- NASA Ames Research Center, MS 239-20, Moffett Field, CA 94035, USA
| | - Goro Komatsu
- International Research School of Planetary Sciences, Università d’Annunzio, Viale Pindaro 42, 65127 Pescara, Italy
| | - Wei Luo
- Department of Geography, Northern Illinois University, DeKalb, IL 60115, USA
| | | | - J.A.P. Rodriguez
- NASA Ames Research Center, MS 239-20, Moffett Field, CA 94035, USA
- Planetary Science Institute, Tucson, AZ 85719, USA
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30
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Schulze-Makuch D, Schulze-Makuch A, Houtkooper JM. The Physical, Chemical and Physiological Limits of Life. Life (Basel) 2015; 5:1472-86. [PMID: 26193325 DOI: 10.3390/life5031472] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 07/07/2015] [Accepted: 07/13/2015] [Indexed: 01/12/2023] Open
Abstract
Life on Earth displays an incredible diversity in form and function, which allows it to survive not only physical extremes, but also periods of time when it is exposed to non-habitable conditions. Extreme physiological adaptations to bridge non-habitable conditions include various dormant states, such as spores or tuns. Here, we advance the hypothesis that if the environmental conditions are different on some other planetary body, a deviating biochemistry would evolve with types of adaptations that would manifest themselves with different physical and chemical limits of life. In this paper, we discuss two specific examples: putative life on a Mars-type planet with a hydrogen peroxide-water solvent and putative life on a Titan-type planetary body with liquid hydrocarbons as a solvent. Both examples would have the result of extending the habitable envelope of life in the universe.
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Coates AJ, Wellbrock A, Waite JH, Jones GH. A new upper limit to the field-aligned potential near Titan. Geophys Res Lett 2015; 42:4676-4684. [PMID: 27609997 PMCID: PMC4994318 DOI: 10.1002/2015gl064474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 05/22/2015] [Indexed: 06/06/2023]
Abstract
Neutral particles dominate regions of the Saturn magnetosphere and locations near several of Saturn's moons. Sunlight ionizes neutrals, producing photoelectrons with characteristic energy spectra. The Cassini plasma spectrometer electron spectrometer has detected photoelectrons throughout these regions, where photoelectrons may be used as tracers of magnetic field morphology. They also enhance plasma escape by setting up an ambipolar electric field, since the relatively energetic electrons move easily along the magnetic field. A similar mechanism is seen in the Earth's polar wind and at Mars and Venus. Here we present a new analysis of Titan photoelectron data, comparing spectra measured in the sunlit ionosphere at ~1.4 Titan radii (RT) and at up to 6.8 RT away. This results in an upper limit on the potential of 2.95 V along magnetic field lines associated with Titan at up to 6.8 RT, which is comparable to some similar estimates for photoelectrons seen in Earth's magnetosphere.
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Affiliation(s)
- Andrew J Coates
- Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK
| | - Anne Wellbrock
- Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK
| | | | - Geraint H Jones
- Mullard Space Science Laboratory University College London London UK; Centre for Planetary Sciences at UCL/Birkbeck London UK
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32
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Neish CD, Barnes JW, Sotin C, MacKenzie S, Soderblom JM, Le Mouélic S, Kirk RL, Stiles BW, Malaska MJ, Le Gall A, Brown RH, Baines KH, Buratti B, Clark RN, Nicholson PD. Spectral properties of Titan's impact craters imply chemical weathering of its surface. Geophys Res Lett 2015; 42:3746-3754. [PMID: 27656006 PMCID: PMC5012121 DOI: 10.1002/2015gl063824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 04/22/2015] [Accepted: 04/23/2015] [Indexed: 06/06/2023]
Abstract
We examined the spectral properties of a selection of Titan's impact craters that represent a range of degradation states. The most degraded craters have rims and ejecta blankets with spectral characteristics that suggest that they are more enriched in water ice than the rims and ejecta blankets of the freshest craters on Titan. The progression is consistent with the chemical weathering of Titan's surface. We propose an evolutionary sequence such that Titan's craters expose an intimate mixture of water ice and organic materials, and chemical weathering by methane rainfall removes the soluble organic materials, leaving the insoluble organics and water ice behind. These observations support the idea that fluvial processes are active in Titan's equatorial regions.
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Affiliation(s)
- C. D. Neish
- Department of Physics and Space SciencesFlorida Institute of TechnologyMelbourneFloridaUSA
| | - J. W. Barnes
- Department of PhysicsUniversity of IdahoMoscowIdahoUSA
| | - C. Sotin
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - S. MacKenzie
- Department of PhysicsUniversity of IdahoMoscowIdahoUSA
| | - J. M. Soderblom
- Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of TechnologyCambridgeMassachusettsUSA
| | - S. Le Mouélic
- Laboratoire de Planétologie et Géodynamique, LPGNantes, CNRS UMR 6112, Université de NantesNantesFrance
| | - R. L. Kirk
- United States Geological Survey, Astrogeology Science CenterFlagstaffArizonaUSA
| | - B. W. Stiles
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - M. J. Malaska
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - A. Le Gall
- Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS)Université de Versailles Saint‐QuentinParisFrance
| | - R. H. Brown
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonArizonaUSA
| | - K. H. Baines
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - B. Buratti
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCaliforniaUSA
| | - R. N. Clark
- United States Geological SurveyDenverColoradoUSA
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Abeysekera C, Joalland B, Ariyasingha N, Zack LN, Sims IR, Field RW, Suits AG. Product Branching in the Low Temperature Reaction of CN with Propyne by Chirped-Pulse Microwave Spectroscopy in a Uniform Supersonic Flow. J Phys Chem Lett 2015; 6:1599-1604. [PMID: 26263320 DOI: 10.1021/acs.jpclett.5b00519] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new chirped-pulse/uniform flow (CPUF) spectrometer has been developed and used to determine product branching in a multichannel reaction. With this technique, bimolecular reactions can be initiated in a cold, thermalized, high-density molecular flow and a broadband microwave spectrum acquired for all products with rotational transitions within a chosen frequency window. In this work, the CN + CH3CCH reaction was found to yield HCN via a direct H-abstraction reaction, whereas indirect addition/elimination pathways to HCCCN, CH3CCCN, and CH2CCHCN were also probed. From these observations, quantitative branching ratios were established for all products as 12(5)%, 66(4)%, 22(6)%, and 0(8)% into HCN, HCCCN, CH3CCCN, and CH2CCHCN, respectively. The values are consistent with statistical calculations based on new ab initio results at the CBS-QB3 level of theory. This work is a demonstration of CPUF as a powerful technique for quantitatively determining the branching into polyatomic products from a bimolecular reaction.
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Affiliation(s)
- Chamara Abeysekera
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Baptiste Joalland
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Nuwandi Ariyasingha
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Lindsay N Zack
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
| | - Ian R Sims
- ‡Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042, Rennes CEDEX, France
| | - Robert W Field
- §Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Arthur G Suits
- †Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States
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34
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Stevenson J, Lunine J, Clancy P. Membrane alternatives in worlds without oxygen: Creation of an azotosome. Sci Adv 2015; 1:e1400067. [PMID: 26601130 PMCID: PMC4644080 DOI: 10.1126/sciadv.1400067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 02/05/2015] [Indexed: 06/05/2023]
Abstract
The lipid bilayer membrane, which is the foundation of life on Earth, is not viable outside of biology based on liquid water. This fact has caused astronomers who seek conditions suitable for life to search for exoplanets within the "habitable zone," the narrow band in which liquid water can exist. However, can cell membranes be created and function at temperatures far below those at which water is a liquid? We take a step toward answering this question by proposing a new type of membrane, composed of small organic nitrogen compounds, that is capable of forming and functioning in liquid methane at cryogenic temperatures. Using molecular simulations, we demonstrate that these membranes in cryogenic solvent have an elasticity equal to that of lipid bilayers in water at room temperature. As a proof of concept, we also demonstrate that stable cryogenic membranes could arise from compounds observed in the atmosphere of Saturn's moon, Titan, known for the existence of seas of liquid methane on its surface.
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Affiliation(s)
- James Stevenson
- School of Chemical and Biomolecular Engineering, Cornell University, 365 Olin Hall, Ithaca, NY 14853, USA
| | - Jonathan Lunine
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - Paulette Clancy
- School of Chemical and Biomolecular Engineering, Cornell University, 365 Olin Hall, Ithaca, NY 14853, USA
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Barnes JW, Sotin C, Soderblom JM, Brown RH, Hayes AG, Donelan M, Rodriguez S, Mouélic SL, Baines KH, McCord TB. Cassini/VIMS observes rough surfaces on Titan's Punga Mare in specular reflection. ACTA ACUST UNITED AC 2014; 3:3. [PMID: 27512619 PMCID: PMC4959132 DOI: 10.1186/s13535-014-0003-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 06/19/2014] [Indexed: 11/28/2022]
Abstract
Cassini/VIMS high-phase specular observations of Titan’s north pole during the T85 flyby show evidence for isolated patches of rough liquid surface within the boundaries of the sea Punga Mare. The roughness shows typical slopes of 6°±1°. These rough areas could be either wet mudflats or a wavy sea. Because of their large areal extent, patchy geographic distribution, and uniform appearance at low phase, we prefer a waves interpretation. Applying theoretical wave calculations based on Titan conditions our slope determination allows us to infer winds of 0.76±0.09 m/s and significant wave heights of \documentclass[12pt]{minimal}
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$2^{+2}_{-1}$
\end{document}2−1+2 cm at the time and locations of the observation. If correct, these would represent the first waves seen on Titan’s seas, and also the first extraterrestrial sea-surface waves in general.
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Affiliation(s)
- Jason W Barnes
- Department of Physics, University of Idaho, Moscow, 83844-0903 Idaho USA
| | - Christophe Sotin
- Jet Propulsion Laboratory, Caltech, Pasadena, 91109 California USA
| | - Jason M Soderblom
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, 02141 MA USA
| | - Robert H Brown
- Lunar and Planetary Laboratory, University of Arizona, Tucson, 85721 Arizona USA
| | | | | | - Sebastien Rodriguez
- Laboratoire AIM, Université Paris Diderot/CEA Irfu/CNRS, Centre de l'orme des Mérisiers, bât. 709, Gif/Yvette Cedex, 91191 France
| | - Stéphane Le Mouélic
- Laboratoire de Planétologie et Géodynamique, CNRS UMR6112, Université de Nantes, Nantes, France
| | - Kevin H Baines
- Space Science and Engineering Center, University of Wisconsin, Madison, 53706 WI USA
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Carrasco N, Giuliani A, Correia JJ, Cernogora G. VUV photochemistry simulation of planetary upper atmosphere using synchrotron radiation. J Synchrotron Radiat 2013; 20:587-590. [PMID: 23765300 DOI: 10.1107/s0909049513013538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 05/16/2013] [Indexed: 06/02/2023]
Abstract
The coupling of a gas reactor, named APSIS, with a vacuum-ultraviolet (VUV) beamline at the SOLEIL synchrotron radiation facility, for a photochemistry study of gas mixtures, is reported. The reactor may be irradiated windowless with gas pressures up to hundreds of millibar, and thus allows the effect of energetic photons below 100 nm wavelength to be studied on possibly dense media. This set-up is perfectly suited to atmospheric photochemistry investigations, as illustrated by a preliminary report of a simulation of the upper atmospheric photochemistry of Titan, the largest satellite of Saturn. Titan's atmosphere is mainly composed of molecular nitrogen and methane. Solar VUV irradiation with wavelengths no longer than 100 nm on the top of the atmosphere enables the dissociation and ionization of nitrogen, involving a nitrogen chemistry specific to nitrogen-rich upper atmospheres.
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Affiliation(s)
- Nathalie Carrasco
- Université de Versailles St-Quentin/UPMC Université Paris 06, CNRS, LATMOS, F-78280 Guyancourt, France.
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Poppinga D, Schoenfeld A, Chofor N, Poppe B. SU-E-T-224: Dose Distribution of Oesophagus Stents Measured by EBT2 Film Dosimetry. Med Phys 2012; 39:3755. [PMID: 28517333 DOI: 10.1118/1.4735287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study is to investigate the dose enhancement at oesophagus stents made of nitinol. The material is a nickel titan alloy with an effective atomic number of 26. Because of the increased atomic number in comparison to the human body, dose enhancement in surrounding tissue is expected. METHODS The relative dose distribution around the stent was measured in a water phantom. To simulate the air cavity within the oesophagus, a styrodur cylinder was placed inside the stent. The stent was held with a circular PMMA holder. An EBT2 film was wrapped around the stent to measure the relative radial dose distribution.The setup was irradiated with a 6MV photon beam (Siemens Primus) and a field size of 5cmx5cm. The distance between source and centre of the stent was 100cm.The EBT2 films were digitized at a scanning resolution of 72dpi using an Epson 10000XL flatbed scanner with a transparency unit. Furthermore, the films were fixed in a frame to prevent Newton rings in the scanned image. RESULTS The dose increases in all directions around the stent. With approximately 18%, the highest increase is caused on the proximal side of the stent. On the backside the dose enhancement is approximately 10%. CONCLUSIONS Dose enhancements around a stent are detectable and one should be aware of it's occurence in the radiotherapeutical treatment of oesophageal cancer. Because of the enhancement in all directions healthy tissue may be affected.
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Affiliation(s)
- D Poppinga
- University Oldenburg, Oldenburg, Germany.,Pius Hospital, Oldenburg, Germany
| | - A Schoenfeld
- University Oldenburg, Oldenburg, Germany.,Pius Hospital, Oldenburg, Germany
| | - N Chofor
- University Oldenburg, Oldenburg, Germany.,Pius Hospital, Oldenburg, Germany
| | - B Poppe
- University Oldenburg, Oldenburg, Germany.,Pius Hospital, Oldenburg, Germany
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