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  • 1
    facet.materialart.
    Unknown
    A multifunctional aqueous channel formed by CFTR (1992)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1992-11-27
    Description: The cystic fibrosis gene product (CFTR) is a complex protein that functions as an adenosine 3,5-monophosphate (cAMP)-stimulated ion channel and possibly as a regulator of intracellular processes. In order to determine whether the CFTR molecule contains a functional aqueous pathway, anion, water, and urea transport were measured in Xenopus oocytes expressing CFTR. Cyclic AMP agonists induced a Cl- conductance of 94 microsiemens and an increase in water permeability of 4 x 10(-4) centimeter per second that was inhibited by a Cl- channel blocker and was dependent on anion composition. CFTR has a calculated single channel water conductance of 9 x 10(-13) cubic centimeter per second, suggesting a pore-like aqueous pathway. Oocytes expressing CFTR also showed cAMP-stimulated transport of urea but not the larger solute sucrose. Thus CFTR contains a cAMP-stimulated aqueous pore that can transport anions, water, and small solutes. The results also provide functional evidence for water movement through an ion channel.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hasegawa, H -- Skach, W -- Baker, O -- Calayag, M C -- Lingappa, V -- Verkman, A S -- DK35124/DK/NIDDK NIH HHS/ -- DK43840/DK/NIDDK NIH HHS/ -- HL42368/HL/NHLBI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1992 Nov 27;258(5087):1477-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, University of California, San Francisco 94143-0532.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1279809" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Biological Transport/physiology ; Chlorides/metabolism ; Cyclic AMP/physiology ; Cystic Fibrosis Transmembrane Conductance Regulator ; Female ; Humans ; In Vitro Techniques ; Ion Channels/*physiology ; Membrane Proteins/*physiology ; Molecular Sequence Data ; Oocytes ; Urea/metabolism ; Water/metabolism ; Xenopus
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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    PAPER CURRENT
  • 2
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    Ground exposure of composite materials for helicopters (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Residual strength results are presented on four composite material systems that were exposed for three years at locations on the North American Continent. The exposure locations are near the areas where Bell Model 206L Helicopters, that are in a NSA/U.S. Army sponsored flight service program, are flying in daily commercial service. The composite systems are: (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 Graphite/E-788 epoxy. All material systems exhibited good strength retention in compression and short beam shear. The Kevlar-49/LRF-277 epoxy retained 88 to 93 percent of the baseline strength while the other material systems exceeded 95 percent of baseline strength. Residual tensile strength of all materials did not show a significant reduction. The available moisture absorption data is also presented.
    Keywords: COMPOSITE MATERIALS
    Format: text
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  • 3
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    Unknown
    Worldwide flight and ground-based exposure of composite materials (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The long-term durability of those advanced composite materials which are applicable to aircraft structures was discussed. The composite components of various military and commercial aircraft and helicopters were reviewed. Both ground exposure and flight service were assessed in terms of their impact upon composite structure durability. The ACEE Program is mentioned briefly.
    Keywords: COMPOSITE MATERIALS
    Type: ACEE Composite Struct. Technol.; p 17-50
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Flight service environmental effects on composite materials and structures (1992)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: NASA Langley and the U.S. Army have jointly sponsored programs to assess the effects of realistic flight environments and ground-based exposure on advanced composite materials and structures. Composite secondary structural components were initially installed on commercial transport aircraft in 1973; secondary and primary structural components were installed on commercial helicopters in 1979; and primary structural components were installed on commercial aircraft in the mid-to-late 1980's. Service performance, maintenance characteristics, and residual strength of numerous components are reported. In addition to data on flight components, 10 year ground exposure test results on material coupons are reported. Comparison between ground and flight environmental effects for several composite material systems are also presented. Test results indicate excellent in-service performance with the composite components during the 15 year period. Good correlation between ground-based material performance and operational structural performance has been achieved.
    Keywords: COMPOSITE MATERIALS
    Type: AGARD, The Utilization of Advanced Composites in Military Aircraft; 13 p
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Fatigue characterization of advanced carbon-carbon composites (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Response of quasi-isotropic laminates of SiC coated Carbon-Carbon (C/C) composites under flexural fatigue are investigated at room temperature. Virgin as well as mission cycled specimens are tested to study the effects of thermal and pressure cycling on the fatigue performance of C/C. Tests were conducted in three point bending with a stress ratio of 0.2 and frequency of 1 Hz. Fatigue strength of C/C has been found to be considerably high - approximately above 85 percent of the ultimate flexural strength. The fatigue strength appears to be decreasing with the increase in the number of mission cycling of the specimens. This lower strength with the mission cycled specimens is attributed to the loss of interfacial bond strength due to thermal and pressure cycling of the material. C/C is also found to be highly sensitive to the applied stress level during cyclic loading, and this sensitivity is observed to increase with the mission cycling. Weibull characterization on the fatigue data has been performed, and the wide scatter in the Weibull distribution is discussed. Fractured as well as untested specimens were C-scanned, and the progressive damage growth during fatigue is presented.
    Keywords: COMPOSITE MATERIALS
    Type: In: International Congress on Experimental Mechanics, 7th, Las Vegas, NV, June 8-11, 1992, Proceedings. Vol. 2 (A94-12901 02-39); p. 1368-1373.
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Fatigue and flexural response of advanced carbon-carbon composites at room and elevated temperatures (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: The flexural response of SiC-coated carbon-carbon composites (ACC-4) at room and elevated temperatures is presented. Three-point bending tests were performed on virgin and mission-cycled specimens, and the variation in flexural strength is examined. The load-deflection behavior of the material at various temperatures is investigated, and the Weibull (1939) analysis of the strength data is performed. Micrographs of various cross sections in the damaged zone were taken, and the failure mechanisms are discussed. Fatigue tests were conducted under flexural loads, and the S-N diagram with the corresponding Weibull analysis are presented. Untested as well as fractured specimens under static and dynamic loading were C-scanned to identify the damaged zone and visualize the extent of the damage. Failure analyses are presented for both static and cyclic loading on the basis of NDE, the micrographs, and the experimental data.
    Keywords: COMPOSITE MATERIALS
    Type: Ceramic Engineering and Science Proceedings (ISSN 0196-6219); 13; 8-Jul
    Format: text
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  • 7
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    Unknown
    Ground exposure of composite materials for helicopters (1984)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Residual strength results are presented on four composite material systems that were exposed for three years at locations on the North American Continent. The exposure locations are near the areas where Bell Model 206L Helicopters, that are in a NSA/U.S. Army sponsored flight service program, are flying in daily commercial service. The composite systems are: (1) Kevlar-49 fabric/F-185 epoxy; (2) Kevlar-49 fabric/LRF-277 epoxy; (3) Kevlar-49 fabric/CE-306 epoxy; and (4) T-300 Graphite/E-788 epoxy. All material systems exhibited good strength retention in compression and short beam shear. The Kevlar-49/LRF-277 epoxy retained 88 to 93 percent of the baseline strength while the other material systems exceeded 95 percent of baseline strength. Residual tensile strength of all materials did not show a significant reduction. The available moisture absorption data is also presented.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-TM-86311 , AVSCOM-TM-84-B-2 , NAS 1.15:86311 , AHS Natl. Spec. Meeting-Helicopter Testing Technol.; Oct 29, 1984 - Nov 01, 1984; Williamsburg, VA; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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