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  • (1976) Leigh, Herbert

  • (1972) Stuckey, Janet R.
    It was found that all genetic variants for glaucousness over the whole plant involved genes on the chromosomes of group 2. Of three recessive nonglaucous lines which arose spontaneously in Chinese Spring background, all were found to be due to deletion or mutation of the gene for glaucousness on chromosome 2B. Another recessively nonglaucous line which arose in the backcrossing of the inhibitor gene of C.W.S. 5075 into Chinese Spring background was found to have undergone a large terminal deletion of the short arm of chromosome 2B. Chromosome 2D in Chinese Spring was found to bear a weaker gene homoeologous to that on chromosome 2B. It was found that chromosomes 2A bears no gene affecting glaucousness. Two dominant ethyl methanesulfonate induced nonglaucous mutants were identified as alleles of the inhibitor gene on chromosome 2B. The variety Mentana was found to have no fully effective group-2 genes for glaucousness. The recessive gene for nonglaucousness on chromosome 2B of Mentana was mapped as lying between 33 and 50 map units from the centromere. A linkage stu~ gave no recombinants between the Mentana gene and the inhibitor gene from 5075, giving a maximum distance of 8 map units between them. There is a strong case for thinking that both genes are alleles of the Chinese Spring gene for glaucousness. Genes capable of interacting to modi~ the dominance relationship of the 2D inhibitor were found in the ABD XIII background Poso. It was found that an extra dose of chromosome 2B could interact with the genes of ABD XIII to give the same effect as the Poso genotype. Modifier genes in the backgrounds of Poso and 5075 also interacted to alter the dominance of the 2B inhibitor. Group 3 chromosomes were found to bear genes specifically for glaucousness of the peduncle. Chromosome 3A bears the most effective gene, chromosome 3B a less effective one and chromosome 3D apparently bears a null allele. Both Poso and Mentana were found to have genes which could substitute for the chromosome 3A gene of Chinese Spring.

  • (1977) Danilatos, Gerasimos Daniel
    The complex modulus of single keratin fibres has been studied at various extensions or times as well as at different relative humidities, temperatures and frequencies . Two parameters of the complex modulus were measured, namely the dynamic modulus and the loss angle. To carry out measurements for the above studies a dynamic mechanical tester was designed and constructed. By using a piezoelectric element the apparatus allows for measurements to be taken in the frequency range 6 Hz to 1500Hz, while with an environment conditioning chamber the full range of relative humidities and the range of -100°C to + 50°C for temperatures can be covered. Fine fibre samples can be extended in the apparatus and tested at each extension. Considerable precautions were taken in the apparatus to reduce noise because of the small values of the signals detected. By using the above equipment it was found that the modulus of wool fibres decreases with strain up to intermediate extensions of about 20% and then increases with higher extensions. The loss angle variation with extension is inverse to the modulus changes. The complex modulus was also measured while fibres were extension cycled or relaxed at fixed strains. More measurements were taken under other specific conditions of strain. All of these results, it was shown, could be explained by the application of the two-phase structure model of keratin: one phase C being relatively impenetrable to water and possessing elastic properties at all extensions, and the other phase M being water penetrable and acting mechanically as a viscoelastic solid. Measurements on fibres were carried out during abrupt relative humidity changes at a constant frequency and temperature. For an abrupt relative humidity increase it was found that the loss angle vs time exhibits an overshoot at the time when the absorption is nearly completed, while the modulus curve is changing markedly at the same time. This result was compatible with the suggestion that the structural mobility of the keratin fibre reaches a maximum at the time when absorption is almost complete. The complex modulus of wet keratin fibres was measured in the frequency range of 6 - 1500 Hz at different temperatures between 0.2 and 45°C. Some measurements were taken at different relative humidities. These results together with results of other workers indicated the presence of a characteristic transition process in keratin dependent strongly on the water content. This process was attributed to the main chain motion in the M phase.

  • (1976) Seaborn, Colin James
    The chlorination of Fe203 and Fe304 has been investigated in a fluidised bed in the range 850- 950°C in order to elucidate the role of iron in the segregation process for nickeliferous laterites. The kinetics of Fe203 chlorination in the range using 20% HCl - 80% N2 gas mixtures is consistent with a single- stage starvation control model, whereas Fe304 exhibits a two- stage reaction mechanism. Oxygen potential measurements using a CSZ probe located above the bed and X-ray powder results confirm the proposed reaction scheme. When a serpentitic nickeliferous laterite (1.03% Ni - 11.7% Fe) was chlorinated at 900°C with a 2o% HCl - 80% N2 gas mixture it was found that the oxidic iron in the ore was extracted in a similar manner to the synthetic iron oxides. Al so, it was found that the nickel extraction from the ore paralleled that of the iron and the tests indicated that for the major part of the extraction, the solid nickel species were in equilibrium with the gas phase. The results obtained from the chlorination of Fe203 and Fe304 with 2o% HCl - 5% CO - 75% N2 at 900°C indicated that a starvation control model should again be applicable, but, no completely satisfactory model was devised. However, when Fe3o4 was chlorinated in more reducing conditions with 20% HCl - 10% CO - 70% N2 or 10% HCl - 1o% CO - 80% N2 at 90cPC it was found that the rates of iron extraction were consistent with those predicted by a starvation control model. This model assumed equilibrium between Fe3O4/FexO and the gas phase. On extension of these tests to the nickel laterite or e it was found that the iron oxides in the ore reacted in an analogous manner to the synthetic oxides. However, these free iron oxides quickly disappeared from the ore not only due to the rapid rates of chlorination but the interaction between iron species and the silicate minerals also. Hence , initially there was an increase in the iron content of the silicate minerals, but, after all of the iron oxides had been removed the iron in the silicate minerals reacted with the gases. Although increasing the CO content of the reacting gas mixture resulted in a significantly greater rate of iron extraction, there was only a slight effect on the nickel chlorination. This can be explained by applying to the ore a model similar to that developed for the pure iron oxides. CO when added to the reacting gas mixture appeared to lower the ultimate recoveries of both nickel and iron. This apparent effect is not well understood but could be associated with solid state changes in the ore. It has been found that the models devised for chlorination of the iron oxides and ore can be used to explain the fluidised bed results of Webb (40) and Brittan and Liebenberg (7). Furthermore, it was shown by thermodynamic calculations based on the results of Brittan and Liebenberg (7) that the stability of the iron deposited by reduction of the fluidised bed effluent gas could be explained by considering equilibrium of simple gaseous species.