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Some quantitative effects of indoleacetic acid on the wood production and tracheid dimensions of Picea (1977)

Denne, M. P. ; Wilson, J. E.

Springer

Planta 134 (1977), S. 223-228

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ISSN: 1432-2048

Keywords: Auxin ; Cambium ; Gibberellin ; Picea ; Tracheids-wood production

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The diameter and wall thickness of tracheids produced after indoleacetic acid treatment were not significantly different from those of the intact controls, for the first few weeks after treatment of disbudded shoots of Picea abies Karst. and Picea sitchensis (Bong.) Carr. However, lateral application of indoleacetic acid (IAA) to intact shoots increased both tracheid diameter and wall thickness; it is suggested that IAA acted synergistically with another endogenous growth regulator, which was also removed by disbudding. Increase in wall thickness after exogenous IAA was associated with increase in duration of the wall thickening phase of tracheid differentiation; this is discussed in relation to the seasonal change from early to latewood. Cambial dormancy was induced by disbudding during active wood production. Since this occurred with or without the presence of current leaves, it is concluded that in Picea continued cambial activity depends upon supply of auxin from the buds, and cannot be supplied from expanded leaves or from the internode itself. Neither indoleacetic acid nor gibberellic acid stimulated renewed cambial activity when applied after the cessation of wood production. With both disbudded and intact shoots, the effectiveness of exogenous IAA declined with time, probably due to decreasing penetration through callus developing at the wounded surface. It is suggested that this apparent change in IAA effectiveness may explain some discrepancies between the results of previous observers.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00384186

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A statistical study of the effect of formulation variables on the properties of sorbitol polyether-based rigid urethane foam (1960)

Wilson, J. E. ; Truax, H. M. ; Dunn, M. A.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 3 (1960), S. 343-356

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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: Each rigid urethane foam formulation must be carefully designed to meet the key requirements of its specific end use. For example, refrigerator insulation is an application which requires low thermal conductivity, low density, and excellent resistance to humid aging. The present investigation was carried out to determine variations in foam properties caused by changes in catalyst concentration, isocyanate/hydroxyl ratio in the quasi-prepolymer, quasi-prepolymer cooking time, dispersing agent concentration, and isocyanate/hydroxyl ratio in the total foam. The basic foam formulation contained sorbitol polyether (Hydroxyl Number 490), toluene diisocyanate, trichlorofluoromethane blowing agent, catalyst, and dispersing agent. The results showed that the tensile strength decreased as the isocyanate/hydroxyl ratio in the total foam increased. Shear strength was affected strongly by catalyst concentration, and by isocyanate/hydroxyl ratio in the prepolymer and in the total foam. Cure time (at room temperature) was strongly affected by catalyst concentration and technique of prepolymer preparation. The only factors having a significant effect on humid aging resistance were isocyanate/hydroxyl ratio in the prepolymer and in the total foam. The effects on thermal conductivity were complex, and included an interaction between dispersing agent concentration and catalyst concentration, and also between prepolymer preparation technique and isocyanate/hydroxyl ratio in the prepolymer. The compressive strength increased with catalyst concentration, and was strongly affected by prepolymer preparation techniques. Key effects and interactions were plotted in graphical form.

Additional Material: 5 Ill.