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  • 1
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Dtacyl phtluodlolone A and phenolphthtodlo-lone A hpids were isolated from two stratus of Mycobactertum ulcerans. The dlol umts of the phthione A and phenolphth]odlolone A components were shown to have erythro stercochemistry by infrared spectroscopy and proton nuclear magnetic resonance of an acetal derivative This stereoehemistry is shared only by related dvols from M. marmum, the dhols from M. boys, M kansasu, M leprae and M. luberculosiss having threo stereochemlstry.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0959-8103
    Keywords: reaction injection moulding ; polyurea ; polyurethane-urea ; thermomechanical properties ; fracture behaviour ; 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: Segmented copolyureas (PUr) and copoly(urethane-urea)s (PUU) comprising 50% by weight of polyurea hard segments (HS) and polyether soft segment (SS) with different functionalities, have been formed by reaction injection moulding (RIM). The HS were formed from 4,4′-diphenylmethane diisocyanate reacted with mixed isomers of 3,5-diethyltoluene diamine. The nominal functionality of the SS prepolymers used (either amino- or hydroxyl-functionalised polyoxypropylenes with a constant molar mass per functional group of ∼ 2000 g mol-1) was systematically increased from 2 to 4. RIM materials were characterised using dynamic mechanical thermal analysis, differential scanning calorimetry, tensile stress-strain and fracture mechanics studies. Generally, the PUr exhibited far superior thermal-mechanical properties than equivalent PUU materials but inferior fracture resistance, owing to morphological variations resulting from differences in copolymerisation behaviour. For both systems, tensile behaviour was shown to be dominated by the degree of phase separation, whereas fracture properties showed a degree of dependence on SS functionality.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Novel furan-based diisocyanates (2a - c) were reacted with 1-butanol and basic kinetic studies were made. The results were compared with those obtained from 4,4′-methylenediphenylene diisocyanate (1) under similar conditions. The kinetics of these model reactions were found to be complex even in the presence of added catalysts. The isocyanates 2 studied, were shown to behave as benzylic type compounds with reactivities intermediate between those of aryl and alkyl diisocyanates. Comparative studies were made on segmented copolyurethanes prepared from 1 and from a furfuryl diisocyanate 2a having structural similarity to 1. The diol components used in these studies were 1,4-butanediol and polytetrahydrofuran. The segmented co-polyurethanes prepared from the furfuryl diisocyanate can thus be derived from a single naturally occurring source material, namely furfuraldehyde. These polymers were shown by differential scanning calorimetry and dynamic mechanical analysis to possess properties comparable to analogous copolyurethanes derived from oil-based sources.
    Additional Material: 8 Ill.
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  • 6
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Furan-based diisocyanates and diamines were prepared unambiguously as potential monomers for polyurethane and polyamide production, starting from methyl furoate and furfurylamine, respectively. The syntheses were optimized and the product identity was confirmed by elemental analysis, IR and NMR spectroscopy, and also by preparation of derivatives which were similarly characterized.
    Additional Material: 1 Ill.
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  • 7
    Publication Date: 2019-07-12
    Description: The analysis method of Salby (1982) is applied to Stratospheric Sounding Unit brightness temperatures from the TIROS-N and NOAA-6 satellites. The resulting spectra are used to present further evidence for the wave two and three oscillations found by Prata (1984) and to demonstrate the existence of a wave four feature. Maps of synoptic reconstructions of the brightness temperature fields from the spectra are then used to further characterize the warm pools.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 45; 3800-380
    Format: text
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  • 8
    Publication Date: 2019-07-12
    Description: Well-known theoretical predictions suggest that variances of large-scale atmospheric fluctuations, for scales somewhat shorter than those of the forcing mechanisms, should obey a power law, k exp -b, where k is the horizontal wave number. The invariance of the exponent b with season, hemisphere, and latitude is tested using satellite-measured brightness temperatures. Global grids of Tiros-N Microwave Sounding Unit channel 4 measurements, which closely approximate the 30- to 150-mbar layer mean temperature, are constructed for January, March, and August 1979. These grids are zonally Fourier-transformed, and the resulting spectra are averaged over four 18 deg-wide latitude bands. Fits of a power law to these spectra over wave numbers 10-36 and 10-26 give values of b which are independent of season, hemisphere, and latitude band, to within statistical uncertainties. The observed values of b are about 3.6, as compared to theoretical predictions of 3.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 91; 13195-13
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  • 9
    Publication Date: 2019-07-12
    Description: Wave number spectra from Nimbus 7 temperature-humidity infrared radiometer 6.7-micron water vapor data are analyzed using series 4800 km long, in regions free of high clouds and frontal zones. In these regions, the brightness temperatures approximate temperatures on a water vapor isosteric (constant density) surface, rather than averages over a broad vertical layer. Power above the noise can be extracted down to wavelengths of about 60 km. Fitting the power spectrum versus horizontal wave number k to a k to the -nth power law for wavelengths from 60 to a few hundred kilometers gives slopes of n = 2.7 to 3.0, depending on the exact wave numbers that are fitted. Thunderstorms and convective cloud systems may constitute an energy source for the reverse energy cascade which produces a -5/3 spectral slope. The results suggest that when these features are not present, the enstrophy-cascading process that gives a -3 slope may govern the motion at scales smaller than it has heretofore been observed.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 95; 909-913
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  • 10
    Publication Date: 2019-07-12
    Description: The low-frequency geopotential height fluctuations in the Southern Hemisphere were examined on the basis of one-point correlation maps. Results indicate that the 35-60 day fluctuations in the Southern-Hemisphere geopotential heights exhibit wavetrainlike characteristics. Correlations between a midlatitude reference point and tropical microwave temperature data were found to be weak, suggesting that the midlatitude wavetrain is not strongly coupled to the Madden and Julian (1971) 40-50 day oscillation.
    Keywords: METEOROLOGY AND CLIMATOLOGY
    Type: Journal of the Atmospheric Sciences (ISSN 0022-4928); 46; 1826-183
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