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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 309-316 
    ISSN: 1057-9257
    Keywords: optical gas sensing ; polysiloxane ; azobenzene ; NO2 ; molecular modelling ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Siloxane copolymers having as side-chains azobenzene derivatives bearing different electron-withdrawing and donating substituents were deposited as thin films by dip coating, and their behaviour upon exposure to 100 pm NO2 was studied by UV/visible spectroscopy. Electron-donating substituents at the ortho positions on the aromatic rings in the azo unit have significant influence on the absorbance changes produced by exposure to NO2, and this is explained by modelling, which suggests that interaction between the electrophilic nitrogen atom in NO2 and the electron clouds of the azobenzene skeleton is responsible for the sensing process, rather than the formation of a Wheland intermediate or other product of chemical reaction. Especially effective substituents are methoxy groups in either aromatic ring ortho or the azo linkage, which also produce a significant increase in intensity of the long-wavelength n-π* transition. This moves the optical interrogation signal to a wavelength range of particular benefit for potential applications. Copyright © 1998 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 47-52 
    ISSN: 1057-9257
    Keywords: ligand gated ; channel protein ; biomembrane ; biosensor ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: We demonstrate a novel protective configuration for a gated channel biosensor. The bilayer membrane containing the channel proteins is formed by a simple self-assembly technique ensuring continuous coverage of the interface between two slabs of agarose gel by a biomimetic lamella in a fluid state. The gel protects both membrane surfaces from mechanical shock and contact with low-energy media while allowing diffusion of biomolecules up to 10 MDa in weight. The technique has been demonstrated using both dioleoyl-phosphatidylcholine (DOPC) and a phosphatidylcholine lipid cross-linked with a short polysiloxane chain (PSPC). The conductance per unit area of the channel-free membrane produced by this method was less than 25 S m-2 for DOPC and 2 S m-2 for PSPC, and the bilayer nature of the barrier in both cases has been demonstrated by measurement of the capacitance. The applicability to sensors has been confirmed using gramicidin-D, a 1·1 kDa unilamellar lipid bilayer pore former, and partially confirmed using valinomycin, a selective ion transporter. On incorporation of gramicidin the membrane conductance increased by over an order of magnitude. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Advanced Materials for Optics and Electronics 8 (1998), S. 317-324 
    ISSN: 1057-9257
    Keywords: gas sensing ; nitrogen dioxide ; stilbene ; biphenyl ; UV-visible spectroscopy ; thin films ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Thin films of a selection of stilbene and biphenyl side-chain substituted liquid crystal polymers based on polysiloxanes were deposited using an automated dip-coating technique and exposed to either 100 ppm NO2 gas and/or concentrated nitric acid vapour, the consequent effect being monitored by changes in the UV-visible spectra of the material. No effective response to NO2 was observed from the biphenylene analogue, but the stilbene derivatives showed spectral changes to suggest that an interaction occurs between the vapour and the bridge position of the stilbene side-chain. The stilbenes also show a marked pre-conditioning phenomenon upon exposure to nitric acid vapour prior to exposure to nitrogen dioxide. This procedure gives a material that has a more reversible response on exposure to NO2 gas than an anagolous film that has not been pre-treated. Copyright © 1998 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 1607-1617 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: By means of interfacial polycondensation, ultrathin coatings of polyamides, polyurethanes, polyureas, polyesters, polycarbonates, and various copolymers can be formed on the surface of a substrate. If the substrate contains reactive groups (such as —NH2, —OH, —NCO, —COCl, etc.), graft polymer is formed. The graft polymer is not removed by extensive extraction with good solvents for the polymer. In contrast, if wool is used as a substrate and is acetylated prior to the polymerization (to block the grafting sites), the thin coating of polymer is readily extracted. Digestion of the treated wool with enzymes that react with the wool, but not with the grafted coating, permits a characterization of the grafted polymer; amino acid analysis of the residue from the enzyme digestion provides evidence that the grafting sites on the wool are probably the free amino and hydroxyl groups located in the N-terminal amino acids or internal amino acids containing these groups in their side chain.
    Additional Material: 12 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 3159-3176 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The γ-radiation-induced polymerization of pure styrene and styrene-n-dibutyl disulfide mixtures has been studied at a number of temperatures and dose rates. Up to 0.04 Mrad/hr the rates were proportional to the square root of the dose rate. By measuring the rates at a number of disulfide concentrations and at three different dose rates, the relative rates of radical formation were determined by kinetic analysis. Considerable energy transfer from the styrene to the disulfide was found. The relative contributions of energy transfer and radical formation were separated by using the kinetic scheme of Nikitina and Bagdasaryan. Values of 8.5 and 3.1 were found for the relative rates of radical production and energy transfer, respectively. This leads to a G (radical) value of 3.1 for n-dibutyl disulfide. With azobisisobutyronitrile as the initiator, the chain transfer constant to the disulfide was determined at 55°C. Finally, the sulfur content of a number of the polymers were determined, an average of two sulfur atoms per polymer chain was found. In general, the rate of polymerization was found to increase in the presence of dibutyl disulfide.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 2011-08-24
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft (ISSN 0021-8669); 30; 3; p. 334-339.
    Format: text
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  • 7
    Publication Date: 2013-08-31
    Description: A review of Doppler Global Velocimetry (DGV) data obtained during wind tunnel tests on a 75 degree swept delta wing was performed. High frequency variations observed in normalized data files are attributed to image alignment problems. Unfortunately, initial DGV velocity data compared poorly with baseline reference data. Nonlinear DGV system operation during the tests is the likely source of this problem. Corrected data compares much more favorably and suggests that DGV is a valid measurement technique. Future DGV investigations should include a method or means for monitoring laser frequency relative to the ALF transfer function behavior.
    Keywords: AERODYNAMICS
    Type: Old Dominion Univ., NASA/American Society for Engineering Ed; Old Dominion Univ.,
    Format: application/pdf
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  • 8
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in a water tunnel to identify the effects of apex blowing on two delta-wing models undergoing constant pitch-rate motion. One wing was of 60-degree sweep and the other was of 76-degree sweep. Flow visualization methods were utilized to determine vortex burst locations for a wide range of pitch-up (nose up) and plunge (nose down) rates, apex jet strengths, and blowing directions. Results indicate that blowing along the 60-degree wing vortex core or along the 76-degree wing centerline results in a notable improvement in vortex behavior under both static and dynamic conditions. The results are most dramatic during dynamic plunging (nose down) conditions, where blowing resulted in the reformation of vortices with significant length.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 92-0407
    Format: text
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  • 9
    Publication Date: 2019-07-13
    Description: An analytical study was conducted to determine the impact of flight Mach number on inlet type selection for a supersonic cruise aircraft. External and mixed-compression axisymmetric and two-dimensional inlets were considered. The internal contraction of the mixed-compression inlets was limited to achieve self-starting. At Mach 2.0, the axisymmetric mixed-compression inlet provided the best aircraft range. At Mach 2.3, the two-dimensional mixed-compression inlet was the most attractive if enough variable geometry were incorporated to minimize spillage during subsonic cruise. Increases in takeoff-to-cruise air flow ratio gave lower aircraft range.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 80-1807 , Aircraft Systems Meeting; Aug 04, 1980 - Aug 06, 1980; Anaheim, CA
    Format: text
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