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(1) Oxygen flux in waterlogged forest soils can be measured using the platinum microcathode technique. By automatically scanning a predetermined voltage range applied to each set of up to twenty-four microcathodes in turn, the instrument described produces a set of polarograms from which a flux-derived current can be unambiguously determined. (2) Examples of different types of polarogram are given and the degree of desaturation is indicated by the shape of the polarogram. (3) The robust microcathodes are made of a hard platinum-iridium alloy cased in resin-impregnated glass fibre, the whole instrument being rugged, portable and capable of running unattended in adverse environments. (4) Applied potential and scanning rate can be preselected, usually 0 to --500 mV at 33 mV min[sup-1]. (5) Difficulty in extrapolating transient to steady state diffusion and the uncertainty associated with the exact cathodic process involved are discussed. [ABSTRACT FROM AUTHOR]

The development and characterization of a micro-size two-dimensional polyacrylamide gel electrophoresis system is described. Some of the techniques which have evolved with use of the system are also discussed. This apparatus has unique features which provide advantages over other small scale units. Up to ten first- and second-dimension gels can be processed simultaneously with excellent resolution of protein regions. Consistent reproducibility is possible from protein samples as small as 400 ng and individual protein regions as small as 1 pg can be visualized by silver staining of the two-dimensional gels. Similar sensitivities are achieved in autoradiographs of 3H-labeled proteins extracted from the nuclei of cultured cells. The application of this system in conjunction with flow cytometric examination of nuclear DNA and electrostatic cell sorting of specific cell nuclei to provide homogeneous sample populations, allows subtle variations in isotope incorporation in proteins to be detected; whereas many times in generalized tissue samples these changes are masked. Also, these techniques elucidate the effects of external stimuli (chemicals, drugs, or environment) on protein synthesis and phosphorylation for analyses and comparison. Fabrication drawings are available upon request. [ABSTRACT FROM AUTHOR]

Abstract: The U.S. Heavy Ion Fusion program is developing superconducting focusing quadrupoles for near-term experiments and future driver accelerators. Following the fabrication and testing of several models, a baseline quadrupole design was selected and further optimized. The first prototype of the optimized design has achieved a conductor-limited gradient of 132T/m in a 70mm bore, with measured field harmonics within 10 parts in 104. In parallel, a compact focusing doublet was fabricated and tested using two of the first-generation quadrupoles. After assembly in the cryostat, both magnets reached their conductor-limited quench current. Further optimization steps are currently underway to improve the performance of the magnet system and reduce its cost. They include the fabrication and test of a new prototype quadrupole with reduced field errors as well as improvements of the cryostat design for the focusing doublet. The prototype focusing units will be installed in the HCX beamline at LBNL, to perform accelerator physics experiments and gain operational experience. Successful results in the present phase will make superconducting magnets a viable option for the next generation of integrated beam experiments. [Copyright &y& Elsevier]