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  • 1
    Electronic Resource
    Electronic Resource
    Transistion from laminar to turbulent flow in pipes (1959)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 5 (1959), S. 433-435 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In pipeline design, for which one needs a means of ascertaining whether the flow will be laminar or turbulent, the Reynolds number is the criterion for Newtonian fluids. The principal purpose of this study was to formulate a more general criterion to characterize the flow regime and to test this form in application to non-Newtonian fluids.Intuitive physical arguments suggested the use of a local stability parameter which is a function of the ratio of input energy to energy dissipation for an element of fluid. If the parameter is applied to a Newtonian fluid in laminar pipe flow, one finds that it has a maximum value of 0.385 times the critical Reynolds number, or 808. As the criterion is presumed to be general, it is inferred that the value of 808 defines the boundary between stable laminar and stable turbulent pipe flow for all fluids. The inference has been varified for several pseudoplastic fluids.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690050407
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  • 2
    Electronic Resource
    Electronic Resource
    Bubble shapes in nucleate boiling (1966)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 12 (1966), S. 344-348 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An attempt is made to explain the differently shaped bubbles observed growing on a surface during nucleate boiling of water. Some of the bubbles photographed were very close to the spherical shape, while others were close to the hemispherical. Also, a number of bubbles had intermediate shapes and were called oblate bubbles.Measurements of bubble dimensions and growth rates obtained from high-speed films were analyzed. By using a modified Rayleigh equation, the relative importance of the inertial and surface tension forces was computed. it appeared that the differences in shapes among bubbles can be explained on the basis of the relative importance of these forces.It was found that for spherical bubbles inertial forces are small because of the slow growth rate and surface tension is clearly the dominant force. For hemispherical bubbles, however, the fast growth rate causes a very large inertial force which is greater than surface tension. For the oblate bubbles neither of the forces was found to be dominate and inertia as well as surface tension determines the shape.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690120225
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure of the endosymbionts of the whitefly,Bemisia tabaci andTrialeurodes vaporariorum (1993)
    Springer
    Protoplasma 176 (1993), S. 106-115 
    Details
    ISSN: 1615-6102
    Keywords: Whitefly ; Bacteria ; Symbiosis ; Micro-organism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the mycetocytes and mycetome micro-organisms of the sweetpotato whitefly,Bemisia tabaci Genn. andTrialeurodes vaporariorum West are described. InB. tabaci, two morphologically distinct types of micro-organisms were observed in mycetocytes. The predominant type lacked a distinct cell wall, was pleomorphic in shape with a surrounding vacuole. The second type was a coccoid organism, with inner and outer cell membranes. The coccoid organism was often found in groups of varying number within vacuoles, and in many cases appeared to be undergoing degradation. InT. vaporariorum mycetocytes, pleomorphic and coccoid organisms were found, although the coccoid micro-organism inT. vaporariorum, had a thicker cell wall than the coccoid micro-organism inB. tabaci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378946
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  • 4
    Electronic Resource
    Electronic Resource
    Morphological variation inBemisia endosymbionts (1995)
    Springer
    Protoplasma 189 (1995), S. 194-202 
    Details
    ISSN: 1615-6102
    Keywords: Bacteria ; Bemisia tabaci ; Bemisia argentifolii ; Endosymbionts ; Microorganism ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the endosymbionts of several populations of whitefly (Homoptera: Aleyrodidae) was examined using transmission electron microscopy. Consistent differences in morphology and relative number of endosymbionts were observed between species and biotypes of whitefly within the Bemisia taxon.Bemisia argentifolii (=B. tabaci B biotype) individuals from Hawaii, Florida, and Arizona contained two morphological types of microorganisms housed within the mycetocyte cells of immature whiteflies. In contrast, individuals from populations ofB. tabaci A biotype from Arizona and Mexico, andB. tabaci Jatropha biotype from Puerto Rico, consistently contained three distinct morphological types of microorganisms within their mycetocytes. Organisms fromB. tabaci A and Jatropha biotypes differed from each other in the relative frequency of each type of microorganism. These observations suggest that different whitefly biotypes may have variable combinations of micro-fauna, with some possibly unique to each group, and furthers the hypothesis that variation in whitefly endosymbionts may be associated with the development of biotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280174
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  • 5
    Electronic Resource
    Electronic Resource
    Diffusion of stabilizers in polymers. I. 2,4-dihydroxybenzophenone in polyolefins (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 319-334 
    Details
    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: The diffusion of the ultraviolet stabilizer 2,4-dihydroxybenzophenone in compressionmolded sheets of low-density polyethylene, high-density polyethylene, and isotactic polypropylene was investigated over the temperature range of 44-75°C. The magnitude of the diffusion coefficients for these polyolefins was found to decrease in the order low-density polyethylene 〉 high-density polyethylene 〉 polypropylene, the corresponding activation energies being approximately 18, 23, and 34 kcal/mole. Studies under conditions of saturation indicated that the migration of this stabilizer was confined to the more accessible amorphous regions of the polymers. The rate of loss of stabilizer from polymer samples immersed in water was also investigated at 44°C. Values of the diffusion coefficients calculated from the results of these studies were somewhat greater than those determined from the diffusion studies for the low-density polyethylene and isotactic polypropylene samples and considerably smaller in the case of high-density polyethylene. The extraction studies also permitted the quantitative evaluation of the solubilities of the stabilizer in the polymers. These were found to be 0.003, 0.03, and 0.07 wt-% for high-density polyethylene, low-density polyethylene, and polypropylene, respectively, at 44°C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070190201
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  • 6
    Electronic Resource
    Electronic Resource
    Diffusion of stabilizers in polymers. III. 2,4-dihydroxybenzophenone and 2-hydroxy-4-octoxybenzophenone in polyurethanes (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 2533-2539 
    Details
    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: The diffusion of the radioactively labeled ultraviolet stabilizers 2,4-dihydroxybenzophenone and 2-hydroxy-4-octoxybenzophenone in two linear poly(ester-urethanes) was studied over the temperature range 36-75°C. Within this temperature range, both stabilizers diffused faster in the polyurethane which had a polyester of molecular weight 2000 in its chain rather than in the polyurethane with a polyester of molecular weight 1000 in its chain. 2,4-Dihydroxybenzophenone diffused slightly faster than 2-hydroxy-4-octoxybenzophenone in both polyurethanes. In each case, the results can be represented by an Arrhenius expression D = D0 exp (-E/RT). The values of D0 and E are discussed in terms of the size of the stabilizer molecular and the structure of the polymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200920
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  • 7
    Electronic Resource
    Electronic Resource
    Diffusion of stabilizers in polymers. II. 2-hydroxy-4-octoxybenzophenone in polyolefins (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 1745-1754 
    Details
    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: The migration of radioactively labeled 2-hydroxy-4-octoxybenzophenone in a number of polyolefins was investigated over the temperature range 36-75°C. The rates of diffusion in the polymers studied were found to decrease in the order low-density polyethylene 〉 high-density polyethylene ∼ isotactic polypropylene, the activation energies being approximately 17, 36, and 24 kcal/mole, respectively. The results of the present study were found to be in qualitative agreement with those previously determined for the same stabilizer/polymer systems, quantitative differences being attributed to the different methods of sample preparation and the resulting differences in the morphological structures of the test specimens. The calculated solubilities of the substituted 2-hydroxybenzophenone in the various polymers were substantially higher, at a particular temperature, than the corresponding values previously determined for 2,4-dihydroxybenzophenone, being 1.4, 0.4, and 0.8 wt-% for low-density polyethylene, high-density polyethylene, and polypropylene, respectively at 75°C. Studies to determine the rate of loss of the stabilizer from polymer samples immersed in water resulted in extremely low rates of extraction, in contrast to those found for 2,4-dihydroxybenzophenone, as a result of the octoxy substituent and the resulting increase in compatibility between the stabilizer and polymer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070190624
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  • 8
    Electronic Resource
    Electronic Resource
    Diffusion of stabilizers in polymers. IV. 2,4-dihydroxybenzophenone in plasticized poly(vinyl chloride) (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 3457-3463 
    Details
    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: The diffusion of the radioactively labeled ultraviolet stabilizer 2,4-dihydroxybenzophenone in compression-molded sheets of plasticized poly(vinyl chloride) was studied over the temperature range of 30°C-75°C. No detectable diffusion occurred in the 0% and 10% plasticized poly(vinyl chloride) when the diffusion temperature was below the glass transition temperatures of the polymers. Diffusion coefficients have been measured for plasticizer concentrations of 20, 30, 40, and 50 wt%. In each case, the variation of the diffusion coefficient D with temperature T can be represented by an Arrhenius expression D = D0 exp(-E/RT). The linear relation log D0 = -7.1 + 0.20E/T was obtained as an empirical expression of the results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070211221
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  • 9
    Electronic Resource
    Electronic Resource
    Reactivities of phenylethylenes towards the benzoyloxy radical (1967)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 102 (1967), S. 73-82 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mit Hilfe von mit 14C markiertem Dibenzoylperoxid wurden bei 60°C die Reaktions fähigkeiten verschiedener Phenyläthylene gegen das Benzoyloxyradikal verglichen, und zwar nach zwei verschiedenen Methoden. Einmal wird die Wirkung der ungesättigten Verbindung auf die Kohlendioxidausbeute während der Zersetzung des Dibenzoylperoxids in Benzol verfolgt. Beim anderen wird das Verhältnis von Benzoyloxy- zu Phenylendgruppen in Polymeren und Copolymeren bestimmt. Die Geschwindigkeitskonstanten für die Addition des Bezugsradikals an Styrol, trans-Stilben, cis-Stilben, 1,1-Diphenyläthylen, Triphenyläthylen und Tetraphenyläthylen verhalten sich wie 2,6:12,4:8,3:7,3:11,7:0.
    Notes: Tracer techniques involving 14C-benzoyl peroxide have been used to compare the reactivities at 60°C. of various phenylethylenes towards the benzoyloxy radical. Two general procedures have been used. One involves a study of the effect of the unsaturated compound upon the yield of carbon dioxide during decomposition of benzoyl peroxide in benzene. The other depends upon determination of the relative numbers of benzoyloxy and phenyl end-groups in polymers and co-polymers. The velocity constants for addition of the reference radical to styrene, trans-stilbene, cis-stilbene, 1:1-diphenylethylene, triphenylethylene, and tetraphenylethylene are in the proportions 2.6:12.4:8.3:7.3:11.7:0.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1967.021020106
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  • 10
    Electronic Resource
    Electronic Resource
    The use of chlorine-36 in polymer chemistryDedicated to Prof. Dr. G. V. SCHULZ on the occasion of his 60th birthday (1965)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 87 (1965), S. 66-72 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Verwendung von Chlor-36 im Hinblick auf eine Isotopenmarkierung bei der Copolymerisation von Methylmethacrylat und Methyl-α-chloracrylat wurde untersucht. Für die Kontrolle des 36Cl ist die Flüssigkeits-Scintillationszählung geeignet. Für die Löschung ist eine Korrektur erforderlich; es kann ein einfaches Verfahren angewendet werden.
    Notes: The use of chlorine-36 in connection with a tracer study of the copolymerization of methyl methacrylate and methyl α-chloroacrylate has been examined. Scintillation counting in solution is suitable for the assay of the chlorine isotope; corrections for quenching must be made and a simple procedure can be applied.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1965.020870106
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