A census of semisymmetric cubic graphs on up to 768 vertices

A list is given of all semisymmetric (edge- but not vertex-transitive) connected finite cubic graphs of order up to 768. This list was determined by the authors using Goldschmidt's classification of finite primitive amalgams of index (3,3), and a computer algorithm for finding all normal subgroups of up to a given index in a finitely-presented group. The list includes several previously undiscovered graphs. For each graph in the list, a significant amount of information is provided, including its girth and diameter, the order of its automorphism group, the order and structure of a minimal edge-transitive group of automorphisms, its Goldschmidt type, stabiliser partitions, and other details about its quotients and covers. A summary of all known infinite families of semisymmetric cubic graphs is also given, together with explicit rules for their construction, and members of the list are identified with these. The special case of those graphs having K_1,3 as a normal quotient is investigated in detail. Supported in part by N.Z. Marsden Fund (grant no. UOA 124) and N.Z. Centres of Research Excellence Fund (grant no. UOA 201) Supported in part by “Ministrstvo za šolstvo, znanost in šport Slovenije”, research program no. 101-506. Supported in part by research projects no. Z1-4186-0101 and no. Z1-3124-0101. The fourth author would like to thank the University of Auckland for hospitality during his visit there in 2003.     

On-line nuclear orientation at KOOL

Since the previous conference we extended our series of on-line -anisotropy measurements in the Z=50 and Z=82 region leading a.o. to the identification of the phase transition in the Au isotopes. Besides conventional on-line low temperature nuclear orientation, we introduced the first on-line applications of NMR/ON, on-line -anisotropy measurements and -decay asymmetry experiments. The intriguing information from these new developments both in the field of nuclear structure and solid state physics is briefly discussed.     

High-performance liquid chromatographic determination of ochratoxin A and its 4R-4-hydroxy metabolite in human urine

One of the metabolites of ochratoxin A (OA) is 4R-4-hydroxyochratoxin A (4-OH-OA), and the ratio of 4-OH-OA to OA excreted in urine can be linked to the carcinogenic potential of this compound. As further support to the hypothesis that OA can be involved in Balkan endemic nephropathy and the associated urinary system tumours, it was decided to investigate the presence of these two compounds in the urine of affected populations. A sensitive method is described for the determination of the compounds at the 10 ng l-1 level. It involves extraction, two purification steps by column chromatography and high-performance liquid chromatography (HPLC), an analysis by HPLC and a confirmatory test by HPLC after derivatisation.