Self-assembly of a heteroleptic one-dimensional chain comprising different dinuclear meso-helicates in the solid-state

We describe two mesocate assemblies that contain either an ethylene glycol or ammonium group which form a heteroleptic one-dimensional infinite chain in the solid state

An investigation into processes influencing the morphodynamics of an intertidal mudflat, the Dollard Estuary, The Netherlands

I. Hydrodynamics and Suspended sediment As part of an interdisciplinary experiment, a series of measurements have been obtained on the mudflats of the Dollard Estuary, the Netherlands. The aim was to investigate the sediment transport and accumulation processes occurring during the covering and uncovering of the mudflats, particularly as the area was known to be ebb current dominant. Current velocity measurements confirmed the ebb dominance, and suspended matter concentrations measured over several tidal cycles in calm weather revealed that the highest concentrations occurred at the beginning of the flood and the end of the ebb. The resulting sediment flux, however, was flood dominant. During windy weather the balance of flux changed to ebb dominance. Measurements of floc size and settling velocity show a major organic component produced by entrainment of a thin surface layer during the early flood tide. During a windy period settling velocities in the adjacent channel together with the concentration variations showed a phase lag with water depth and velocity. The highest settling velocities occurred at about slack water, and there were residual ebb fluxes of suspended sediment. It is concluded that the ebb dominance of the currents is not apparent in the sediment fluxes during calm weather, but in periods of high winds the flux is likely to be ebb directed, except when diatom productivity is high. The overall response is similar to that of flood dominated mudflats

Intercomparison of in situ suspended matter (floc) size measurements

International audienceSimultaneous measurements of in situ particle (floc) size were performed with different instruments during several tidal cycles in the Elbe estuary in June 1993. Comparison of the size distributions (by volume) indicates that six instruments produced data that could be compared, while two instruments produced only estimates of mean, minimum and maximum size. The minimum size measured was related to the characteristics of the instrument, the maximum size to the concentration (by number) of the largest flocs, to the volume of the water measured, and to the degree of floc break-up during handling and/or measuring of the sample. The size distributions generally follow a log-probability curve so that the differences in size range measured do not strongly influence the median values. The variability of the results obtained with different instruments shows that measurements can best be made with only one instrument so that a maximum of consistency is obtained

The Simulated Indian Monsoon: A GCM Sensitivity Study

The authors find that the deficiency of the model precipitation simulation may be attributed to the use of an enhanced orography in the integrations. Replacement of this orography with a mean orography results in a much more realistic simulation of Indian monsoon circulation and rainfall. Experiments with a linear primitive equation model on the sphere suggest that this striking improvement is due to modulations of the orographically forced waves in the lower troposphere. This improvement in the monsoon simulation is due to the kinematic and dynamical effects of changing the topography, rather than the thermal effects, which were minimal. The magnitude of the impact on the Indian monsoon of the other sensitivity experiments varied considerably but was consistently less than the impact of using the mean orography. However, results from the soil moisture sensitivity experiments suggest a possibly important role for soil moisture in simulating tropical precipitation. -from Author