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  • Lunar and Planetary Science and Exploration  (4)
  • Cell & Developmental Biology  (3)
  • 2010-2014  (4)
  • 1995-1999
  • 1985-1989  (3)
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  • 1
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    Assessments of Potential Rock Coatings at Rocknest, Gale Crater with ChemCam (2013)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Many locations on Mars have low color contrast between the rocks and soils due to the rocks being "dusty"--basically having a surface that is spectrally similar to Martian soil. In general this has been interpreted as soil and/or dust clinging to the rock though either mechanical or electrostic processes. However, given the apparent mobility of thin films of water forming cemented soils on Mars and at Gale Crater, the possibility exists that some of these "dusty" surfaces may actually be coatings formed by thin films of water locally mobilizing soil/air fall material at the rock interface. This type of coating was observed by Spirit during an investigation of the rock Mazatzal which showed enhanced salts above "normal soil" and an enhancement of nano phase iron oxide that was ~ 10 micronmeters thick. We decided to use ChemCam to investigate the possibility of similar rock coatings forming at the Rocknest site at Gale Crater.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Lunar and Planetary Science Conference; Mar 18, 2013 - Mar 22, 2013; The Woodlands, TX; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Calibration of the MSL/ChemCam/LIBS Remote Sensing Composition Instrument (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The ChemCam instrument suite on board the 2011 Mars Science Laboratory (MSL) Rover, Curiosity, will provide remote-sensing composition information for rock and soil samples within seven meters of the rover using a laser-induced breakdown spectroscopy (LIBS) system, and will provide context imaging with a resolution of 0.10 mradians using the remote micro-imager (RMI) camera. The high resolution is needed to image the small analysis footprint of the LIBS system, at 0.2-0.6 mm diameter. This fine scale analytical capability will enable remote probing of stratigraphic layers or other small features the size of "blueberries" or smaller. ChemCam is intended for rapid survey analyses within 7 m of the rover, with each measurement taking less than 6 minutes. Repeated laser pulses remove dust coatings and provide depth profiles through weathering layers, allowing detailed investigation of rock varnish features as well as analysis of the underlying pristine rock composition. The LIBS technique uses brief laser pulses greater than 10 MW/square mm to ablate and electrically excite material from the sample of interest. The plasma emits photons with wavelengths characteristic of the elements present in the material, permitting detection and quantification of nearly all elements, including the light elements H, Li, Be, B, C, N, O. ChemCam LIBS projects 14 mJ of 1067 nm photons on target and covers a spectral range of 240-850 nm with resolutions between 0.15 and 0.60 nm FWHM. The Nd:KGW laser is passively cooled and is tuned to provide maximum power output from -10 to 0 C, though it can operate at 20% degraded energy output at room temperature. Preliminary calibrations were carried out on the flight model (FM) in 2008. However, the detectors were replaced in 2009, and final calibrations occurred in April-June, 2010. This presentation describes the LIBS calibration and characterization procedures and results, and details plans for final analyses during rover system thermal testing, planned for early March.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-22815 , 42nd Lunar and Planetary Science Conference; Mar 07, 2011 - Mar 11, 2011; The Woodlands, TX; United States
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  • 3
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    A Comparison of Multivariate and Pre-Processing Methods for Quantitative Laser-Induced Breakdown Spectroscopy of Geologic Samples (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The ChemCam instrument selected for the Curiosity rover is capable of remote laser-induced breakdown spectroscopy (LIBS).[1] We used a remote LIBS instrument similar to ChemCam to analyze 197 geologic slab samples and 32 pressed-powder geostandards. The slab samples are well-characterized and have been used to validate the calibration of previous instruments on Mars missions, including CRISM [2], OMEGA [3], the MER Pancam [4], Mini-TES [5], and Moessbauer [6] instruments and the Phoenix SSI [7]. The resulting dataset was used to compare multivariate methods for quantitative LIBS and to determine the effect of grain size on calculations. Three multivariate methods - partial least squares (PLS), multilayer perceptron artificial neural networks (MLP ANNs) and cascade correlation (CC) ANNs - were used to generate models and extract the quantitative composition of unknown samples. PLS can be used to predict one element (PLS1) or multiple elements (PLS2) at a time, as can the neural network methods. Although MLP and CC ANNs were successful in some cases, PLS generally produced the most accurate and precise results.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-22820 , 42nd Lunar and Planetary Science Conference; Mar 07, 2011 - Mar 11, 2011; The Woodlands, TX; United States
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  • 4
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    Dust Removal on Mars Using Laser-Induced Breakdown Spectroscopy (2011)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Dust coatings on the surface of Mars complicate and, if sufficiently thick, mask the spectral characteristics and compositional determination of underlying material from in situ and remote sensing instrumentation. The Laser-Induced Breakdown Spectroscopy (LIBS) portion of the Chemistry & Camera (ChemCam) instrument, aboard the Mars Science Laboratory (MSL) rover, will be the first active remote sensing technique deployed on Mars able to remove dust. ChemCam utilizes a 5 ns pulsed 1067 nm high-powered laser focused to less than 400 m diameter on targets at distances up to 7 m [1,2]. With multiple laser pulses, dust and weathering coatings can be remotely analyzed and potentially removed using this technique [2,3]. A typical LIBS measurement during MSL surface operations is planned to consist of 50 laser pulses at ~14 mJ, with the first 5 to 10 pulses used to analyze as well as remove any surface coating. Additionally, ChemCam's Remote Micro-Imager (RMI) is capable of resolving 200 m details at a distance of 2 m, or 1 mm at 10 m [1,4]. In this study, we report on initial laboratory experiments conducted to characterize the removal of dust coatings using similar LIBS parameters as ChemCam under Mars-like conditions. These experiments serve to better understand the removal of surface dust using LIBS and to facilitate the analysis of ChemCam LIBS spectral data and RMI images.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-22813 , 42nd Lunar and Planetary Science Conference; Mar 07, 2011 - Mar 11, 2011; The Woodlands, TX; United States
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  • 5
    Electronic Resource
    Electronic Resource
    Respiratory metabolism of L-929 cells at different water contents and volumes (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 124 (1985), S. 299-304 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Oxygen consumption was measured in mouse L-929 cells whose volumes and water contents were reduced by adding sorbitol to the medium. The volume of water lost due to a given sorbitol supplement exceeded the loss in apparent cell volume. An explanation is given for this discrepancy. The rate of oxygen uptake in the absence of exogenous respiratory substrate was essentially the same in cells whose total volume was reduced by 45%, amounting to a loss of about 70% of the total cell water, compared to controls at ‘physiological’ volume and water content. Cells under these same conditions responded to added substrates (pyruvate, glucose, and glutamine) and inhibitors (iodoacetate and 2-deoxyglucose) in nearly the same way as control cells. These observations are in accord with and add to previous work showing that very large fluctuations in cell volume and water content have only modest effects on the rates and directions of a variety of metabolic processes. The results are interpreted in terms of current views on the composition and organization of the aqueous compartments of eucaryotic cells.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041240220
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  • 6
    Electronic Resource
    Electronic Resource
    L-929 cells under hyperosmotic conditions: Volume changes (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 129 (1986), S. 367-374 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Volume changes resulting from the addition of sorbitol to the environment of mouse L-929 cells were evaluated from cell diameter measurements. Over periods of 1 hour or less, this solute was effectively excluded from intracellular water. The reduction in cell volume was inversely related to sorbitol concentration up to levels of about 0.6 molal, above which no further significant reduction occurred. Reduced cell volumes were maintained for at least 1 hour without measurable volume regulation. The percentage of volume lost was independent of the initial cell volume and was quickly regained when physiological conditions were restored. However, cell volume was influenced strongly by cell density or by some variable related to it. L-cells store surface area when dehydrated, apparently by means of plasma membrane convolutions and microvilli, based on the rapid kinetics of reversible volume changes and on observations from scanning electron microscopy. These results are related to current views on the nature of intracellular organization.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041290315
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of in utero and in vitro incubation on the lipid-bound fatty acids and sterols of porcine spermatozoa (1987)
    New York, NY : Wiley-Blackwell
    Gamete Research 18 (1987), S. 153-162 
    Details
    ISSN: 0148-7280
    Keywords: sperm ; phospholipid ; neutral lipid ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Sperm-rich semen and washed porcine spermatozoa were incubated for up to 2 hr either in utero in the presence of oviduct fluid or in vitro at 37°C. Sperm lipids were extracted and separated into phospholid and neutral lipid fractions. Eleven phospholipid and five neutral lipid fatty acids were identified and quantified using GC and GC-MS. The percentage of 22:5n6, the major phospholipid fatty acid, decreased slightly but significantly during 1.5 hr of in utero incubation (41.2-38.0%), but after 2.0 hr of in utero incubation no significant difference was observed (40.0%). None of the phospholipid fatty acids changed in concentration during in vitro incubation. The mole ratio of phospholipid to phospholipid fatty acid (1.00:1.27) did not change during incubation. The levels of neutral lipid-bound 14:0 decreased (43.5% to 31.8%) and that of 18:0 increased (11.1% to 18.2%) during in utero incubation. Similar but less pronounced changes were observed during in vitro incubation. (43.5% to 36.0%; and 11.1% to 15.8%, respectively).Two major sterols, cholestrol (73%) and desmosterol (27%) were identified by gas chromatography-mass spectrometry. The mole ratio of phospholipid to sterol (2.47:1:00) did not change during incubation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120180206
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