Dissolved reactive and organic phosphorus (DRP and DOP, respectively) in samples from river and coastal areas of Tokyo Bay, Japan, was size fractionated into high‐molecular‐weight (HMW; <0.1 µm but >10 kDa) and lowmolecular‐weight (LMW, <10 kDa) size classes using a stirred‐cell ultrafiltration system. The LMW fraction accounted for 54–76% of the bulk DOP. LMW‐DOP exhibited conservative behavior during mixing with saline waters, with high concentrations at the river mouth decreasing seaward. HMW‐DOP was a rather minor component, accounting for 14–36% of the bulk DOP. Concentrations of HMW‐DRP, a trace component of all samples, decreased with increasing salinity. Characterization using two phosphohydrolytic enzymes, alkaline phosphatase and phosphodiesterase, demonstrated the presence of three forms of HMW‐DOP: easily hydrolyzable mono‐ and diesters and unhydrolyzable nonreactive DOP. The nonreactive DOP was a significant fraction (up to 67%) of HMW‐DOP. Further size fractionation and characterization revealed the importance of hydrophobic compounds (presumably phospholipids) and phosphate esters as the nonreactive DOP. The esters in the nonreactive fraction are potentially labile but may be protected against decomposition by forming submicron particles and/or macromolecular complexes.
The collisional merging experiments of the field-reversing configuration (FRC) at supersonic/Alfvénic velocities have been performed in the FRC Amplification via Translation-Collisional Merging device only in Japan. This experiment may excite shockwaves and cause particle acceleration. To obtain supporting evidence of particle acceleration by shockwaves, we have proposed to observe neutrons originating from the D–D fusion reaction of accelerated non-thermal particles. A plastic scintillation detector has been developed for the supersonic/Alfvénic collision/merging FRC experiment. The developed neutron detector has sufficient performance of neutron sensitivity and nanosecond response time. In the collisional merging process, we obtained a signal that could be considered a neutron, which is not predicted by the adiabatic compression process in the two-dimensional magnetohydrodynamics simulation.
Measurements of the surface pressure fluctuation, Mach number profile and high speed schlieren visualization have been conducted in the boundary layer on a sharp cone model in a hypersonic flow. Growth rate of the 2nd mode are reduced from the pressure fluctuation measurement and are compared with the analytical prediction based on the similar solution for the cone boundary layer, with moniroring the non-linear phase coupling by bicoherence. The second mode wave propagation direction and phase velocity are also reduced from the fluctuation measurement which confirms two dimensional propagation. Auto-correlation of the fluctuation components of the schlieren images has shown an averaged 2nd mode instability wave structure, when the pressure fluctuation amplitude becomes the same order of the static pressure.