The capacity of two maize opaque endosperm mutants (o1 and o2) and two floury (fl1 and fl2) to accumulate lysine in the seed in relation to their wild type counterparts Oh43+ was examined. The highest total lysine content was 3.78% in the o2 mutant and the lowest 1.87% in fl1, as compared with the wild type (1.49%). For soluble lysine, o2 exhibited over a 700% increase, whilst for fl3 a 28% decrease was encountered, as compared with the wild type. In order to understand the mechanisms causing these large variations in both total and soluble lysine content, a quantitative and qualitative study of the N constituents of the endosperm has been carried out and data obtained for the total protein, nonprotein N, soluble amino acids, albumins/globulins, zeins and glutelins present in the seed of the mutants. Following two-dimensional PAGE separation, a total of 35 different forms of zein polypeptides were detected and considerable differences were noted between the five different lines. In addition, two enzymes of the aspartate biosynthetic pathway, aspartate kinase and homoserine dehydrogenase were analyzed with respect to feedback inhibition by lysine and threonine. The activities of the enzymes lysine 2-oxoglutate reductase and saccharopine dehydrogenase, both involved in lysine degradation in the maize endosperm were also determined and shown to be reduced several fold with the introduction of the o2, fl1 and fl2 mutations in the Oh43+ inbred line, whereas wild-type activity levels were verified in the Oh43o1 mutant.

The capacity of three maize endosperm opaque mutants (o10, o11 and o13) to accumulate soluble lysine in the seed in relation to their wildtype counterpart, W22+, was investigated. The W22o13 and W22o11 mutants exhibited 278% and 186% increases in soluble lysine, respectively, while for W22o10, a 36% decrease was observed, compared with the wildtype. A quantitative and qualitative study of the N constituents of the endosperm has been conducted and data obtained for the total protein, non-protein N, soluble amino acids, albumins / globulins, zeins and glutelins present in the seed of the mutants. Following 2D–PAGE, a total of 38 different forms of zein polypeptides were detected and considerable differences were noted between the three mutant lines. The metabolism of lysine was also studied by analysis of the enzymes aspartate kinase, homoserine dehydrogenase, lysine 2-oxoglutarate reductase and saccharopine dehydrogenase, which exhibited major changes in activity, depending on the genotype, suggesting that the mutant genes may have distinct regulatory activities.

Twin disc tests were carried out to evaluate the wear resistance and Rolling Contact Fatigue (RCF) of premium R400HT rail samples in contact with E8 wheel samples. The wear rate and friction coefficient were correlated with the frictional work expended at the contact interface (the Tgamma approach). Accelerated RCF tests were also carried out on the premium R400HT rail and the results were compared to those obtained for standard R260 rail. The wear rates of rail samples were consistently lower than those reported in the literature for other contacting pairs in which the rail material studied is softer than R400HT. Also, the energy needed for the transition from the moderate to severe wear regime significantly increased for the hardened rail. Fatigue cracks were shallower for R400HT when compared with standard rail material. Hardened rails also showed lower mean spacing between fatigue cracks. This new information can be used to improve wear simulations of wheels and rails by using more realistic wear equations.

Two high lysine maize endosperm mutations, opaque-5 (o5) and opaque-7 (o7), were biochemically characterized for endosperm protein synthesis and lysine metabolism in immature seeds. Albumins, globulins, and glutelins, which have a high content of lysine, were shown to be increased in the mutants, whereas zeins, which contain trace concentrations of lysine, were reduced in relation to the wild-type lines B77xB79+ and B37+. These alterations in the storage protein fraction distribution possibly explain the increased concentration of lysine in the two mutants. Using two-dimensional polyacrylamide gel electrophoresis of proteins of mature grains, variable amounts of zein polypeptides were detected and considerable differences were noted between the four lines studied. The analysis of the enzymes involved in lysine metabolism indicated that both mutants have reduced lysine catabolism when compared to their respective wild types, thus allowing more lysine to be available for storage protein synthesis.