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  • Polymer and Materials Science  (373)
  • United States  (181)
  • Lunar and Planetary Science and Exploration  (126)
  • 1
    Electronic Resource
    Electronic Resource
    Piezoelectric ceramic implants: A feasibility studyPortions of this work were presented at the Fifth Annual Meeting of the Society for Biomaterials, Clemson, SC, April 28-May 2, 1979. (1980)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 14 (1980), S. 269-277 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A piezoelectric ceramic has been investigated as a direct substitute for hard tissues. Barium titanate (BaTiO3) powder was slipcast and fired at 1430°C for 2 hr, then made piezoelectric by polarizing. After 16 and 86 days of implantation in the cortex of the femoral midshafts, the femora with test specimens were sectioned into about 4-cm lengths. Their voltage outputs were measured under cyclic load at 1 Hz. The present results show that the voltage gradient at the implant surface is 0.15 mV/mm for the 16-day implantation with a 445-N (100-lbs.) load. This in turn can give rise to about 0.01 μA current flow in the adjacent area of the 16-day implant. The 86-day implant showed an order of magnitude higher voltage output compared to the 16-day implant with the same magnitude of loads. This is probably due to the “load-transfer” efficiency through the implants, since the voltage output is directly proportional to the actual load transferred to the implant. The more bone implant interface matures, the better the load transfer occurs through the implant, resulting in higher voltage output.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820140308
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  • 2
    Electronic Resource
    Electronic Resource
    Piezoelectric ceramic implants: in vivo resultsPortions of this work were presented at the Fifth Annual Meeting of the Society for Biomaterials, Clemson, SC, 28 April-2 May, 1979. (1981)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 15 (1981), S. 103-110 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The suitability of barium titanate (BaTiO3) ceramic for direct substitution of hard tissues was evaluated using both electrically stimulated (piezoelectric) and inactive (nonpolarized) test implants. Textured cylindrical specimens, half of them made piezoelectric by polarization in a high electric field, were implanted into the cortex of the midshaft region of the femora of dogs for various periods of time. Interfacial healing and biocompatibility of the implant material were studied using mechanical, microradiographical, and histological techniques. Our results indicate that barium titanate ceramic shows a very high degree of biocompatibility as evidenced by the absence of inflammatory or foreign body reactions at the implant-tissue interface. Furthermore, the material and its surface porosity allowed a high degree of bone ingrowth as evidenced by microradiography and a high degree of interfacial tensile strength. No difference was found between the piezoelectric and the electrically neutral implant-tissue interfaces. Possible reasons for this are discussed. The excellent mechanical properties of barium titanate, its superior biocompatibility, and the ability of bone to form a strong mechanical interfacial bond with it, makes this material a new candidate for further tests for hard tissue replacement.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820150114
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  • 3
    Electronic Resource
    Electronic Resource
    Adsorption of hydrogen fluoride on alumina (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 19 (1992), S. 139-144 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In the smelting of aluminium, HF fumes are produced that are subsequently trapped by absorption onto alumina. The factors that affect the adsorption capacity of alumina have been studied previously and are well established, but the mechanism by which HF adsorbs onto the alumina surface is not well understood.In this study, x-ray photoelectron spectroscopy (XPS) was used to investigate the nature of the surface adsorption of HF on alumina. XPS is particularly well suited to the study of this type of gas adsorption process.Laboratory-prepared samples were studied with particular interest in evidence for Al—F bonding, or in fluoride species formed by reaction with —OH or —O. Also of interest was the role of sodium, since it is segregated to the surface of the alumina during calcination.Al—F bonding was observed on only one sample type. An Al—F interaction was identified when the alumina had been predried and dry HF was absorbed. When moisture was present no AlF3 formation was observed. This suggests that under conventional conditions (i.e. moisture present) the adsorption of HF involves a weak interaction, probably hydrogen bonding, with intermediate layers of water. After heating the samples containing weakly bound HF to 500°C, no Al—F interaction was observed. Much of the HF was desorbed at 700°C.An Na-F interaction was observed in all fluoride-adsorbed samples; however, this can only account for a small proportion of the total fluoride adsorbed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740190127
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  • 4
    Electronic Resource
    Electronic Resource
    Photodegradation of copolymers of methyl methacrylate and methyl acrylate at elevated temperatures (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 1425-1435 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four methyl methacrylate - methyl acrylate copolymers with molar ratios, MMA/MA, of 112/1, 26/1, 7·7/1, and 2/1 have been photodegraded at 170°C by 2537 Å radiation. The changes which occur in the molecular weight of the copolymers are typical of a random scission process and from these and volatilization data the extent of chain scission during the course of the reaction has been calculated. The pattern of volatile products is the same as that previously obtained in the thermal reaction at 300°C although there are a number of differences in detail. For example, only one in ten of the methyl acrylate units is liberated as monomer compared with one in four in the thermal reaction and the ratio CO2/chain scissions is considerably greater than the strict 1/1 ratio observed in the thermal reaction. Zip lengths are also very much greater in the photo reaction. These minor differences between the two reactions have been accounted for in terms of the mechanism previously presented to account for the thermal reaction, bearing in mind the differences in the temperature (170 and 300°C) at which the two investigations were carried out.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150070606
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  • 5
    Electronic Resource
    Electronic Resource
    Direct measurements of the mechanical properties of polymerized and unpolymerized langmuir-blodgett films (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1289-1300 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanical measurements can be made on Langmuir-Blodgett (LB) films that have been peeled from their substrates, and are floating on the surface of water, by compressing them between the moving barrier and the Langmuir balance float in a standard monolayer trough. We have used this technique, which utilizes apparatus commonly available where LB films are made, to study multilayers of lead 10,12-tricosadiynoate (a diacetylene carboxylic acid) that were first polymerized and then peeled from the substrate. For comparison we have performed the same measurements on pieces of mylar, on unpolymerized films, and on films of calcium octadecanoate (a saturated chain fatty acid). We found Young's modulus for films of the saturated chain material, the unpolymerized diynoate, and the polymerized films, to be 6 GPa (900 kpsi), 0.5 GPa, and 6 GPa, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1989.090270608
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  • 6
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    Observations of the north polar region of Mars from the Mars orbiter laser altimeter (1998)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5-kilometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied. Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily H2O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x 10(6) to 1.7 x 10(6) cubic kilometers is about half that of the Greenland ice cap. Clouds observed over the polar cap are likely composed of CO2 that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Science (ISSN 0036-8075); Volume 282; 5396; 2053-60
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    The global topography of Mars and implications for surface evolution (1999)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Elevations measured by the Mars Orbiter Laser Altimeter have yielded a high-accuracy global map of the topography of Mars. Dominant features include the low northern hemisphere, the Tharsis province, and the Hellas impact basin. The northern hemisphere depression is primarily a long-wavelength effect that has been shaped by an internal mechanism. The topography of Tharsis consists of two broad rises. Material excavated from Hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary. The present topography has three major drainage centers, with the northern lowlands being the largest. The two polar cap volumes yield an upper limit of the present surface water inventory of 3.2 to 4.7 million cubic kilometers.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Science (ISSN 0036-8075); Volume 284; 5419; 1495-503
    Format: text
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    NASA TECHNICAL REPORTS
  • 8
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    Infrared Spectroscopic Analyses of Sulfate, Nitrate, and Carbonate-bearing Atacama Desert Soils: Analogs for the Interpretation of Infrared Spectra from the Martian Surface (2005)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The Atacama Desert of northern Chile is the driest desert on Earth, receiving only a few mm of rain per decade. The Mars climate may, in the past, have been punctuated by short-lived episodes of aqueous activity. The paleo-Martian environment may have had aqueous conditions similar to the current conditions that exist in the Atacama, and Mars soils may have formed with soil chemistry and mineralogy similar to those found in the Atacama. Remote and in-situ analysis of the Martian surface using infrared technology has a long heritage. Future investigations of the subsurface mineralogy are likely to build upon this heritage, and will benefit from real life lessons to be learned from terrestrial analog studies. To that end, preliminary results from a near- and mid-infrared spectroscopic study of Atacama soil profiled at a range of depths are presented.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Lunar and Planetary Science XXXVI, Part 18; LPI-Contrib-1234-Pt-18
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Issues of exploration: human health and wellbeing during a mission to Mars (2003)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Today, the tools are in our hands to enable us to travel away from our home planet and become citizens of the solar system. Even now, we are seriously beginning to develop the robust infrastructure that will make the 21st century the Century of Space Travel. But this bold step must be taken with due concern for the health, safety and wellbeing of future space explorers. Our long experience with space biomedical research convinces us that, if we are to deal effectively with the medical and biomedical issues of exploration, then dramatic and bold steps are also necessary in this field. We can no longer treat the human body as if it were composed of muscles, bones, heart and brain acting independently. Instead, we must lead the effort to develop a fully integrated view of the body, with all parts connected and fully interacting in a realistic way. This paper will present the status of current (2000) plans by the National Space Biomedical Research Institute to initiate research in this area of integrative physiology and medicine. Specifically, three example projects are discussed as potential stepping stones towards the ultimate goal of producing a digital human. These projects relate to developing a functional model of the human musculoskeletal system and the heart. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.
    Keywords: Lunar and Planetary Science and Exploration
    Type: Advances in space research : the official journal of the Committee on Space Research (COSPAR); 31; 1; 7-16
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
    Electronic Resource
    Electronic Resource
    Effect of reaction conditions on the grafting of 2-(dimethylamino)ethyl methacrylate onto hydrocarbon substrates (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1691-1702 
    Details
    ISSN: 0887-624X
    Keywords: grafting ; basic functionalization ; free radical polymerization ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) onto two model hydrocarbons, squalane and n-eicosane, and to linear low density polyethylene (LLDPE) has been investigated. The results of the study indicate that a high reaction temperature, 160°C, and a low concentration of monomer, less than 0.3 M, are optimum conditions for the grafting reaction. Reaction products, which consisted of grafted hydrocarbons and poly(DMAEMA), were separated by solvent extraction and vacuum distillation; samples were then analyzed by NMR and FTIR spectroscopy and size exclusion chromatography. 1H-NMR spectroscopy indicates that grafted squalane contained approximately 6 DMAEMA units per squalane residue. 1H- and 13C-NMR and molecular weight studies strongly suggest that the grafts onto the model hydrocarbons consist of single DMAEMA units. Results of the melt grafting of DMAEMA onto LLDPE show that the grafting efficiency and degree of grafting are substantially lower than were expected from the model system. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320911
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