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Research indicates that concentrations of labile iron in Southern Ocean seawater are generally lowest in surface water columns and higher in deep water. Latitude, however, was found to affect iron profiles, with concentrations lower in the Antarctic Front and higher in the region south of the Antarctic Divergence.

This paper is concerned with round-robin analyses of probabilistic fracture mechanic (PFM) problems of aged RPV material. Analyzed here is a plate with a semi-elliptical surface crack subjected to various cyclic tensile and bending stresses. A depth and an aspect ratio of the surface crack are assumed to be probabilistic variables. Failure probabilities are calculated using the Monte Carlo methods with the importance sampling or the stratified sampling techniques. Material properties are chosen from the Marshall report, the ASME Code Section XI, and the experiments on a Japanese RPV material carried out by the Life Evaluation (LE) subcommittee of the Japan Welding Engineering Society (JWES), while loads are determined referring to design loading conditions of pressurized water reactors (PWR). Seven organizations participate in this study. At first, the procedures for obtaining reliable PFM solutions with low failure probabilities are examined by solving a unique problem with seven computer programs. The seven solutions agree very well with one another, i.e., by a factor of 2 to 5 in failure probabilities. Next, sensitivity analyses are performed by varying fracture toughness values, loading conditions, and pre and in-service inspections. Finally, life extension simulations based on the PFM analyses are performed. It is clearly demonstrated from these analyses that failure probabilities are so sensitive to the change of fracture toughness values that the degree of neutron irradiation significantly influences the judgment of plant life extension.

We have fabricated a fully superconducting generator of 20 kW class, in which both of armature and field coils are made of superconductors. Two different types of excitation system were selected and tested: a brushless excitation method consisted of 'magnetic flux pump' and a conventional excitation method equipped with collector ring and brushes. The paper describes the experimental machine model and the comparison of test results between the two different types of excitation methods.

Photosynthetic production of carbohydrates in phytoplanktons is measured comparing daytime and nighttime levels. The monosaccharide constituents of water-extractable and residual carbohydrates were analyzed using coupled gas chromatography/mass spectrometry and radioactive tracing of isotopic carbon. Daytime production of monosaccharides for both fractions was higher than nighttime levels. Glucose, which is the main monosaccharide component for both carbohydrate fractions, showed significantly decreased production during nighttime.

The differences in daytime and nightime production of fatty acids and amino acids in phytoplanktons was evaluated. In 24-hour time-series experiments, the production rates were analyzed by coupled gas chromatography/mass spectrometry and radioactive tracing of isotopic carbon. The fatty acid composition of the photosynthetic products was found to be maximum between 9:00 and 12:00 hours. There was no definite pattern observed for amino acids. The production rates for both fatty acids and amino acids were lower than those observed for water-extractable carbohydrates and was attibuted to nitogen deficiency in phytoplanktons.