2,114 research outputs found
Pilot Experiments with Electrodialysis and Ozonation for the Production of a Fertilizer from Urine
Pilot tests were performed with a process combination of electrodialysis and ozonation for the removal of micropollutants and the concentration of nutrients in urine. In continuous and batch experiments, maximum concentration factors up to 3.5 and 4.1 were obtained, respectively. The desalination capacity did not decrease significantly during continuous operation periods of several weeks. Membrane cleaning after 195 days resulted in approximately 35% increase in desalination rate. The Yeast Estrogen Screen (YES), a bioassay that selectively detects oestrogenic compounds, confirmed that about 90% of the oestrogenic activity was removed by electrodialysis. HPLC analysis showed that ibuprofen was removed to a high extent, while other micropollutants were below the detection limit. In view of the fact that ibuprofen is among the most rapidly transported micropollutants in electrodialysis processes, this result indicates that electrodialysis provides an effective barrier for micropollutants. Standardised plant growth tests were performed in the field with the salt solution resulting from the treatment by electrodialysis and subsequent ozonation. The results show that the plant height is comparable to synthetic fertilisers, but the crop yield is slightly lower. The latter is probably caused by volatilisation losses during field application, which can be prevented by improved application technologies
A structural evaluation of the tungsten isotopes via thermal neutron capture
Total radiative thermal neutron-capture -ray cross sections for the
W isotopes were measured using guided neutron beams from
the Budapest Research Reactor to induce prompt and delayed rays from
elemental and isotopically-enriched tungsten targets. These cross sections were
determined from the sum of measured -ray cross sections feeding the
ground state from low-lying levels below a cutoff energy, E, where
the level scheme is completely known, and continuum rays from levels
above E, calculated using the Monte Carlo statistical-decay code
DICEBOX. The new cross sections determined in this work for the tungsten
nuclides are: b and
b;
b and b; b and
b; and,
b and b. These results are consistent with
earlier measurements in the literature. The W cross section was also
independently confirmed from an activation measurement, following the decay of
W, yielding values for that are consistent
with our prompt -ray measurement. The cross-section measurements were
found to be insensitive to choice of level density or photon strength model,
and only weakly dependent on E. Total radiative-capture widths
calculated with DICEBOX showed much greater model dependence, however, the
recommended values could be reproduced with selected model choices. The decay
schemes for all tungsten isotopes were improved in these analyses.Comment: 25 pages, 15 figures, 15 table
Renal handling of prednisolone/prednisone: effect of steroid dose and llβ-hydroxysteroid dehydrogenase
The purposes of this study were: (1) to determine under steady-state conditions whether the renal clearance of prednisolone is concentration dependent, and (2) to establish whether the urinary excretion of prednisolone and its biologically inactive 11-dehydro metabolite prednisone depend upon the activity of 11β-hydroxysteroid dehydrogenase (11β-OHSD). For that purpose 10 healthy volunteers were infused to steady state over a 13-h period either at a low (11 μg/h × kg) or a high (70 μg/h × kg) rate with prednisolone on two occasions, once without and once with administration of glycyrrhetinic acid, an inhibitor of 11β-OHSD. Prednisolone and prednisone were measured by high-pressure liquid chromatography. Mean renal clearance values of total or unbound prednisolone were several times higher during the high than the low infusion rate. The fractional renal clearance of unbound prednisolone during the high, but not during the low infusion rate exceeded 1. This indicates that in addition to unbound prednisolone, protein-bound prednisolone is excreted in urine at high plasma concentrations. Inhibition of 11β-OHSD increased the urinary ratios of prednisolone/prednisone in all subjects. Conclusions: (1) The renal clearance of prednisolone is concentration dependent; (2) there must be tubular secretion and/or glomerular filtration of prednisolone bound to plasma proteins; (3) the urinary excretion of prednisolone/prednisone is modulated by the activity of 11 β-OHS
The geometry of a vorticity model equation
We provide rigorous evidence of the fact that the modified
Constantin-Lax-Majda equation modeling vortex and quasi-geostrophic dynamics
describes the geodesic flow on the subgroup of orientation-preserving
diffeomorphisms fixing one point, with respect to right-invariant metric
induced by the homogeneous Sobolev norm and show the local existence
of the geodesics in the extended group of diffeomorphisms of Sobolev class
with .Comment: 24 page
The curvature of semidirect product groups associated with two-component Hunter-Saxton systems
In this paper, we study two-component versions of the periodic Hunter-Saxton
equation and its -variant. Considering both equations as a geodesic flow
on the semidirect product of the circle diffeomorphism group \Diff(\S) with a
space of scalar functions on we show that both equations are locally
well-posed. The main result of the paper is that the sectional curvature
associated with the 2HS is constant and positive and that 2HS allows for a
large subspace of positive sectional curvature. The issues of this paper are
related to some of the results for 2CH and 2DP presented in [J. Escher, M.
Kohlmann, and J. Lenells, J. Geom. Phys. 61 (2011), 436-452].Comment: 19 page
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