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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 329-336 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Detailed friction load-displacement response of four distinct metallic surfaces [one beaded porous metal (CTR) and three cast Co-Cr alloy ingrowth mesh surfaces, nonplanar mesh (INX), cast mesh 1 (CM1), and cash mesh 2 (CM2)] on polyurethane and cancellous bone specimens of six tibiae were measured under different normal stresses (0.1, 0.15, or 0.025 MPa). Bone cubes were obtained from different proximal regions of resurfaced cadaveric tibiae. Both monotonic and cyclic fatigue loadings of up to 4000 cycles at 1 Hz were considered. Comparison of measured results indicated that the friction coefficient was not affected by the magnitude of normal stress and the bone excision site (medial, lateral, anterior, posterior, and central). The CM2 surface showed significantly greater resistance with friction coefficients of more than 0.9 for the bone and 0.8 for the polyurethane. The INX surface yielded the second largest resistance followed by CMI and CTR surfaces. No significant difference was found between these latter two surfaces. Fatigue tests up to 4000 loading-unloading cycles showed about 10% reduction in friction coefficient for CTR and INX surfaces, while negligible reduction was found for CM1 and CM2 surfaces. © 1997 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 41 (1998), S. 65-70 
    ISSN: 0021-9304
    Keywords: swelling ; conductivity ; hydrogels ; immobilized enzymes ; responsive polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The electrical characteristics of a glucose-sensitive polymeric hydrogel have been studied. The hydrogel matrices were prepared by radical polymerization of solutions containing 2-hydroxyethyl methacrylate, N,N-dimethyl aminoethyl methacrylate, tetraethylene glycol dimethacrylate, ethylene glycol, water, and glucose oxidase. The hydrogels displayed faster and higher swelling rates for lower levels of a crosslinking agent. Electrical conductivity was found to be a sensitive measurement of the state of the swelling. A simple model that relates hydrogel swelling and conductivity has been proposed. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 41, 65-70, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 339-343 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectral bandshapes of the ν1(A1), ν3(A1) and ν4(E) vibrations of CH3I were studied as a function of temperature in the liquid phase. Perpendicular diffusion coefficients calculated from ν3 agreed well with earlier reported results. The degenerate CH3 stretching vibration, ν4, was analyzed via fitting by a model incorporating two Lorentzian lineshapes. Values of the parallel diffusion constants, D∥, determined using only the narrower component were in excellent semi-quantitative agreement with those predicted by the free rotor model of molecular reorientation. Analysis of the room-temperatur Raman spectrum of ν5(E) yielded the same value of D∥ as that calculated from ν4. The room-temperature infrared spectral intensities of ν5 were fitted by a model with a narrow Lorentzian containing contributions from rotational and vibrational relaxation superposed on a second component introduced to account for the broad background absorption. D∥ determined from the IR bandwidth was in good agreement with values obtained from the Raman spectra of ν4 and ν5. These results demonstrate the utility of analyzing degenerate vibrational modes to determine the parallel diffusion coefficients in C3v molecules.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 27-30 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectral bandwidths of two A1′ vibrations of 1,3,5-trifluorobenzene (TFB) were measured in the neat liquid as a function of temperature and in the solvents CH2Cl2 and CS2. The Raman and IR linewidths of two E′ modes were also measured in solution. Derived values of the two rotational diffusion constants, D⊥ and D∥, were compared with the predictions of several current theories. It was observed that the Hynes-Kapral-Weinberg (HKW) theory is superior to both the microviscosity-free rotor and Hu-Zwanzig ‘slip’ models of reorientational diffusion. Calculated values of D⊥ and D∥ for TFB in solution using the HKW model are in excellent agreement with the experimentally measured diffusion constants.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 15 (1984), S. 152-155 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polarized and depolarized Raman spectra of the ν2 (CH2 bend) and ν3 (C—Br stretch) vibrations in dibromomethane have been studied as a function of temperature throughout the liquid range. Reorientational correlation times derived from the two modes were simllar in both magnitude and dependence on temperature. This result, together with other structural data, suggests that the rotational dynamics of this molecule in the liquid phase are quasi symmetric-top in character. Vibrational dephasing times calculated from the two lineshapes were also of the same magnitude. However, modulation times determined via the Kubo lineshpae formalism varied markedly between the vibrations. This provides evidence that vibrational dephasing of the bending and stretching modes are influenced by different intermolecular forces in the liquid.
    Additional Material: 3 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 15 (1984), S. 273-276 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polarized and depolarized Raman spectra of the ν6 (C—C3 stretch), ν7 (C—Cl stretch) and ν8 (C—C3 bend) modes of tert-butyl chloride have been studied as a function of temperature in the liquid phase. Isotropic correlation times for the bending mode were found to be 3-4 times longer than values obtained for the two stretching vibrations. An analysis of the isotropic correlation functions using the Kubo lineshape formalism revealed that the less efficient vibrational relaxation of the deformation arises primarily from the lower second monents of this mode. Reorientational times calculated from the two stretching vibrations were almost three times shorter than the earlier reported dipolar relaxation time, indicating that the tumbling motion of tert- butyl chloride is close to the small-step diffusion limit.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 675-678 
    ISSN: 0749-1581
    Keywords: Tribromobenzene ; 13C spin-lattice relaxation times ; correlation times ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C spin-lattice relaxation times and nuclear Overhauser enhancements of protonated carbons in 1, 3, 5-tribromobenzene were measured in a number of solvents of widely varying viscosity, Derived reorientational correlation times were found to increase approximately linearly with solution viscosity, as predicted by hydrodynamic theories of rotational diffusion.Rotational correlation times calculated from the perrin stick model were two to three times longer than the measured τc values. Similarly, correlation times predicted by the Hu-Zwanzig slip model were too small by a factor of two. On the other hand, application of the newer Hynes-Kapral-Weinberg theory furnished reorientational correlation times that were in virtually quantitative agreement with the experimental results.
    Additional Material: 1 Ill.
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  • 8
    Publication Date: 2018-06-11
    Description: The Microwave Limb Sounder (MLS) on Aura is providing an extensive data set on stratospheric winter polar processing, including the first daily global observations of HCl, together with simultaneous measurements of ClO, HNO3, H2O, O3, N2O, and temperature (among others). We present first results charting the evolution of these quantities during the 2004 Antarctic late winter. MLS observations of chlorine deactivation and ozone loss during this period are shown to be consistent with results from the SLIMCAT chemical transport model.
    Keywords: Geophysics
    Type: Geophysical Research Letters; Volume 32; L12817
    Format: text
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  • 9
    Publication Date: 2019-07-13
    Description: The effort this year focused primarily on 118-GHz transmittance experiments. The data analyzed here was collected with the Microwave Temperature Sounder (MTS) radiometer package during the CAMEX deployment of 1993 with the aim of validating current models of atmospheric microwave absorption in the O2 bands near 54 and 118 GHz. Particular attention has been paid to data collected during four flights when the MTS scanned zenith while profiles of downwelling radiances were collected through ascents and descents. These radiances, in conjunction with radiosonde temperature data, permit the retrieval of band-averaged absorption profiles for each channel. The Millimeter-wave Propagation Model (MPM92) provides theoretical expressions for the absorption of microwaves by oxygen and water vapor and accounts for the interference of pressure-broadened spectral lines'. This model is a good fit to laboratory measurements at temperatures ranging from 279-327 K, but it has been suggested that extrapolation to the conditions of the atmospheric tropopause may result in underestimation of absorption by as much as 15 percent. Preliminary results of the analysis of MTS data appear to be in general agreement with the predictions of the MPM model to within the accuracy of the measurements, which through the coldest parts of the atmosphere ranges from less than plus or minus 5 percent in the most opaque channels to greater than plus or minus 10 percent in the most transparent channels. At those altitudes where each channel is most sensitive to changes in absorption, there is some indication that the modeled absorption may be biased low relative to the observations. Accurate instrument calibration provided challenges, particularly when observed radiances were as much as 260 K below the temperatures of the cold calibration load.
    Keywords: Geophysics
    Type: NASA-CR-201473 , NAS 1.26:201473
    Format: application/pdf
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  • 10
    Publication Date: 2019-07-13
    Description: Global satellite observations of ozone and carbon monoxide from the Microwave Limb Sounder (MLS) on the EOS Aura spacecraft are discussed with emphasis on those observations in the 2 15 - 100 hPa region (the upper troposphere and lower stratosphere). The precision, resolution and accuracy of the data produced by the MLS "version 2.2" processing algorithms are discussed and quantified. O3 accuracy is estimated at approx.40 ppbv +5% (approx.20 ppbv +20% at 215 hPa) while the CO accuracy is estimated at approx.30 ppbv +30% for pressures of 147 hPa and less. Comparisons with expectations and other observations show good agreements for the O3 product, generally consistent with the systematic errors quoted above. In the case of COY a persistent factor of approx.2 high bias is seen at 215 hPa. However, the morphology is shown to be realistic, consistent with raw MLS radiance data, and useful for scientific study. The MLS CO data at higher altitudes are shown to be consistent with other observations.
    Keywords: Geophysics
    Type: Journal of Geophysical Research (ISSN 0148-0227); 113
    Format: text
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