Showing papers by "James Cook University published in 1970"

Strength of Models of Rock with Intermittent Joints

Abstract: A series of triaxial compression tests were carried out on five sample types containing various patterns of preformed intermittent jointing. The 4-in. square by 8-in. high samples were built up from parallelepipedal and hexagonal blocks of high strength gypsum plaster exhibiting rock-like mechanical properties. Tests were carried out at confining pressures in the range 0 psi to 2000 psi. The seven modes of failure observed include axial cleavage and a dilational mode at low confining pressures, shear failure through the plaster, planar and non-planar shear failures partly through plaster and partly along the joints, and the formation of multiple conjugate shear planes at the higher confining pressures, either exclusively through the plaster or partly through plaster and partly along joints, the averaging process for calculating shear strength first proposed by the Austrian School of rock mechanics.

Polymerization Kinetics of n-Lauryl Acrylate

Abstract: The polymerization kinetics of n-lauryl acrylate have been investigated in ethyl acetate and n-heptane at 40°C. A high monomer order, 1.6(5), was found in both solvents. Corresponding initiator orders, determined using Azdn and lauroyl peroxide, were slightly less than the usual value of 0.5. Although the chain termination reaction is undoubtedly diffusion controlled from the start of polymerization, diffusion effects dependent on monomer concentration only partly account for the high monomer order. Other possible explanations based on primary radical termination, “cage-effects,” degradative chain transfer, and radical complexing are also not applicable. Contrary to observations with lower acrylate esters, autoacceleration effects do not occur in the high conversion polymerization of n-lauryl acrylate. Ths probably reflects the reduced importance of radical branching reactions with this monomer.

The osphradium of Conus flavidus

Abstract: The osphradium of Conus flavidus, Lamarck has been examined by histological methods. Each lamella consists of 3 clearly defined regions: a dorsal spine and digitiform processes extending ventrally, composed of pseudostratified epithelium and occasional hair cells; a lateral and interdigitating region which contains numerous hair cells arranged in discrete ridges; a lamella nerve originating from the osphradial ganglion which sends a branch down the centre of each digitiform process. Each lamella has ciliary tracts which cause fluid, impinging on the osphradium, to be passed repeatedly between the lamellae and, therefore, to come into contact with the hair cells which are believed to be the primary sensory units of chemoreception in this organ. The whole structure responds immediately to substances dissolved in water by increased lamellar movement and by arching of the whole structure in towards the osphradial axis.

Electrophoretic charge of a cylindrical macroion in aqueous 1 : 1 electrolyte

Abstract: The potential problem is formulated for rodlike macroions and reduced to a single dimensionless equation with appropriate boundary conditions. A method of solution based on piecewise linearization of the potential equation is detailed and compared with two other approaches. It is suggested that the present method yields improved estimates of macroion charges. Some numerical results are included, and the relation between electrophoretic charge and macroion charge is considered.

Factors Affecting Solution Properties of Hemicelluloses

Abstract: Hemicelluloses are polysaccharide cell wall constituents of land plants composed of a branched β-1,4-xylan backbone with pendant L-arabinose and (usually) 4-O-methyl-D-glucuronic acid units, the latter giving the molecule the properties of a polyelectrolyte. In our work on structure and fractionation of hemicelluloses we have become very aware of the importance of such factors as temperature and trace quantities of metal ions on the solution properties of the hemicelluloses, and this paper describes a preliminary investigation of such effects.