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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 440 (1985), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Mathematik 71 (1967), S. 405-423 
    ISSN: 1436-5081
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 357-364 
    ISSN: 1618-2650
    Keywords: Best. von Fluorkohlenwasserstoffen, Chlorkohlenwasserstoffen in Luft ; Chromatographie, Gas ; C1, C2, Spuren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Als Beitrag zur Untersuchung des viel diskutierten Ozonabbaus wurde eine Analysenmethode zur quantitativen Bestimmung von CCl4 (R10), CFCl3 (R11), CF2Cl2 (R 12), CHCl3, CH3-CCl3, C2HCl3 und C2Cl4 ausgearbeitet. Geeignete Methoden der Probenahme, Anreicherung, Detektion und der gesamten gas-chromatographischen Technik ermöglichen Bestimmungen in ppb-Bereich (10−9 V/V) und ppt-Bereich (10−12 V/V) bis herab zur Nachweisgrenze, die für alle genannten Verbindungen bei 10 ppt (V/V) liegt, u. U. auch darunter. Im Spurenbereich ≥ 100 ppt (V/V) werden eine Genauigkeit von 〈 10% und eine Reproduzierbarkeit von 〈 5 % erreicht, wenn die Untersuchung unmittelbar oder wenigstens innerhalb von 2 Tagen nach der Speicherung durchgeführt wird. Ist dies nicht möglich, wird ein besonderes Gas-Sammelgefäß verwendet, von dem aus in das Speicherrohr übergeführt werden kann.
    Notes: Summary As a contribution to the frequently discussed ozone decomposition an analytical method has been elaborated for the quantitative determination of CCl4, CFCl3, CF2Cl2, CHCl3, CH3-CCl3, C2HCl3, and C2Cl4. Suitable methods of sampling, enrichment, detection, and the whole gas-chromatographic operation allow determinations in the ppb range (10−9 V/V) and the ppt-range (10−12 V/V) down to the limit of detection at 10 ppt for all the cited compounds. For trace amounts of ≥ 100 ppt, an accuracy of 〈 10% and a reproducibility of 〈 5 % are reached if the determination is carried out immediately or at least 2 days after storage. If this is impossible, a special gassampling vessel is employed from which the sample is transferred to the storage column.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 1979-01-01
    Print ISSN: 0016-1152
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 5
    Publication Date: 2019-07-19
    Description: The Sample Analysis at Mars (SAM) instrument detected at least 4 distinct CO2 release during the pyrolysis of a sample scooped from the Rocknest (RN) eolian deposit. The highest peak CO2 release temperature (478-502 C) has been attributed to either a Fe-rich carbonate or nano-phase Mg-carbonate. The objective of this experimental study was to evaluate the thermal evolved gas analysis (T/EGA) characteristics of a series of terrestrial Fe-rich carbonates under analog SAM operating conditions to compare with the RN CO2 releases. Natural Fe-rich carbonates (〈53 microns) with varying Fe amounts (Fe(0.66)X(0.34)- to Fe(0.99)X(0.01)-CO3, where X refers to Mg and/or Mn) were selected for T/EGA. The carbonates were heated from 25 to 715 C (35 C/min) and evolved CO2 was measured as a function of temperature. The highest Fe containing carbonates (e.g., Fe(0.99)X(0.01)-CO3) yielded CO2 peak temperatures between 466-487 C, which is consistent with the high temperature RN CO2 release. The lower Fe-bearing carbonates (e.g., Fe(0.66)X(0.34)CO3) did not have peak CO2 release temperatures that matched the RN peak CO2 temperatures; however, their entire CO2 releases did occur within RN temperature range of the high temperature CO2 release. Results from this laboratory analog analysis demonstrate that the high temperature RN CO2 release is consistent with Fe-rich carbonate (approx.0.7 to 1 wt.% FeCO3). The similar RN geochemistry with other materials in Gale Crater and elsewhere on Mars (e.g., Gusev Crater, Meridiani) suggests that up to 1 wt. % Fe-rich carbonate may occur throughout the Gale Crater region and could be widespread on Mars. The Rocknest Fe-carbonate may have formed from the interaction of reduced Fe phases (e.g., Fe2+ bearing olivine) with atmospheric CO2 and transient water. Alternatively, the Rocknest Fe-carbonate could be derived by eolian processes that have eroded distally exposed deep crustal material that possesses Fe-carbonate that may have formed through metamorphic and/or metasomatic processes.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-34426 , American Geophysical Union Conference; Dec 14, 2015 - Dec 18, 2015; San Francisco, CA; United States
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  • 6
    Publication Date: 2019-07-13
    Description: The Sample Analysis at Mars (SAM) instrument onboard the Curiosity rover detect-ed O2 and HCl gas releases from the Rocknest (RN) eolian bedform and the John Klein (JK) and Cumber-land (CB) drill hole materials in Gale Crater (Fig. 1) [1,2]. Chlorinated hydrocarbons have also been detect-ed by the SAM quadrupole mass spectrometer (QMS) and gas chromatography/mass spectrometer (GCMS) [1,2,3,4]. These detections along with the detection of perchlorate (ClO4(-)) by the Mars Phoenix Lander's Wet Chemistry Laboratory (WCL) [5] suggesting perchlo-rate is a possible candidate for evolved O2 and chlorine species. Laboratory thermal analysis of individual per-chlorates has yet to provide an unequivocal tempera-ture match to the SAM O2 and HCl release data [1,2]. Catalytic reactions of Fe phases in the Gale Crater ma-terial with perchlorates can potentially reduce the de-composition temperatures of these otherwise pure per-chlorate/chlorate phases [e.g., 6,7]. Iron mineralogy found in the Rocknest materials when mixed with Ca-perchlorate was found to cause O2 release temperatures to be closer match to the SAM O2 release data and enhance HCl gas releases. Exact matches to the SAM data has unfortnunately not been achieved with Ca-perchlorate-Fe-phase mixtures [8]. The effects of Fe-phases on magnesium perchlorate thermal decomposi-tion release of O2 and HCl have not been evaluated and may provide improved matches to the SAM O2 and HCl release data. This work will evaluate the thermal decomposition of magnesium perchlorate mixed with fayalite/magnetite phase and a Mauna Kea palagonite (HWMK 919). The objectives are to 1) summarize O2 and HCl releases from the Gale Crater materials, and 2) evaluate the O2 and HCl releases from the Mg-perchlorate + Fe phase mixtures to determine if Mg-perchlorate mixed with Fe-phases can explain the Gale Crater O2 and HCl releases.
    Keywords: Space Sciences (General)
    Type: JSC-CN-31131 , International Conference on Mars; Jul 14, 2014 - Jul 18, 2014; Pasadena, CA; United States
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  • 7
    Publication Date: 2019-07-13
    Description: One of the most compelling features of the Gale landing site is its age. Based on crater counts, the formation of Gale crater is dated to be near the beginning of the Hesperian near the pivotal Hesperian/Noachian transition. This is a time period on Mars that is linked to increased fluvial activity through valley network formation and also marks a transition from higher erosion rates/clay mineral formation to lower erosion rates with mineralogies dominated by sulfate minerals. Results from the Curiosity mission have shown extensive evidence for fluvial activity within the crater suggesting that sediments on the floor of the crater and even sediments making up Mt. Sharp itself were the result of longstanding activity of liquid water. Warm/wet conditions on early Mars are likely due to a thicker atmosphere and increased abundance of greenhouse gases including the main component of the atmosphere, CO2. Carbon dioxide is minor component of the Earth's atmosphere yet plays a major role in surface water chemistry, weathering, and formation of secondary minerals. An ancient martian atmosphere was likely dominated by CO2 and any waters in equilibrium with this atmosphere would have different chemical characteristics. Studies have noted that high partial pressures of CO2 would result in increased carbonic acid formation and lowering of the pH so that carbonate minerals are not stable. However, if there were a dense CO2 atmosphere present at the Hesperian/Noachian transition, it would have to be stored in a carbon reservoir on the surface or lost to space. The Mt. Sharp sediments are potentially one of the best places on Mars to investigate these CO2 reservoirs as they are proposed to have formed in the early Hesperian, from an alkaline lake, and record the transition to an aeolian dominated regime near the top of the sequence. The total amount of CO2 in the Gale crater soils and sediments is significant but lower than expected if a thick atmosphere was present at the Hesperian/Noachian boundary. Likewise, the absence of carbonates suggests that CO2- weathering processes similar to those present on Earth were not dominant. Instead it is possible that more exotic CO2 deposition has occurred driven by atmospheric photochemistry and/or degradation of organic carbon.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-32884 , Lunar and Planetary Science Conference; Mar 16, 2015 - Mar 20, 2015; The Woodlands, TX; United States
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  • 8
    Publication Date: 2019-07-19
    Description: The Sample Analysis at Mars (SAM) instrument onboard the Curiosity rover detected O2 and HCl gas releases from the Rocknest (RN) eolian bedform and the John Klein (JK) and Cumberland (CB) drill hole materials in Gale Crater. Chlorinated hydrocarbons have also been detected by the SAM quadrupole mass spectrometer (QMS) and gas chromatography/mass spectrometer (GCMS). These detections along with the detection of perchlorate (ClO4-) by the Mars Phoenix Lander's Wet Chemistry Laboratory (WCL) suggesting perchlorate is a possible candidate for evolved O2 and chlorine species. Laboratory thermal analysis of individual per-chlorates has yet to provide an unequivocal temperature match to the SAM O2 and HCl release data. These detections along with the detection of perchlorate (ClO4-) by the Mars Phoenix Lander's Wet Chemistry Laboratory suggested perchlorate is a possible candidate for evolved O2 and chlorine species. Laboratory thermal analysis of pure perchlorates has yet to provide an unequivocal temperature match to the SAM O2 and HCl release data. Analog laboratory analysis of iron mineralogy detected in Gale materials that was physically mixed with Ca- and Mg-perchlorate has been shown to catalyze lower O2 release temperatures and approach some SAM O2 release data. Instead of physical mixtures used in previous work, the work presented here utilized perchlorate solutions added to Fe phases. This technique allowed for perchlorate to come in closer contact with the Fe-phase and may more closely mimic Mars conditions where humidity can increase enough to cause deliquescence of the highly hygroscopic perchlorate phases. The objective of this work is to: 1) Utilize a laboratory SAM analog instrument to evaluate the O2 release temperatures from Mg- and Ca-perchlorates solutions applied to Fephases detetected in Gale Crate; and 2) Determine if perchlorate solutions can provide improved matches with the SAM O2 temperature release profiles.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-32773 , Lunar and Planetary Science Conference; Mar 16, 2015 - Mar 20, 2015; The Woodlands, TX; United States
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