51 research outputs found
Interaction potentials for soft and hard ellipsoids
Using results from colloid science we derive interaction potentials for
computer simulations of mixtures of soft or hard ellipsoids of arbitrary shape
and size. Our results are in many respects reminicent of potentials of the
Gay-Berne type but have a well-defined microscopic interpretation and no
adjustable parameters. Since our potentials require the calculation of similar
variables, the modification of existing simulation codes for Gay-Berne
potentials is straightforward. The computational performance should remain
unaffected.Comment: 8 pages, 4 figure
Capillary pressure of van der Waals liquid nanodrops
The dependence of the surface tension on a nanodrop radius is important for
the new-phase formation process. It is demonstrated that the famous Tolman
formula is not unique and the size-dependence of the surface tension can
distinct for different systems. The analysis is based on a relationship between
the surface tension and disjoining pressure in nanodrops. It is shown that the
van der Waals interactions do not affect the new-phase formation thermodynamics
since the effect of the disjoining pressure and size-dependent component of the
surface tension cancel each other.Comment: The paper is dedicated to the 80th anniversary of A.I. Rusano
Pesticide Fate and Transport throughout Unsaturated Zones in Five Agricultural Settings, USA
Computed effect of decomposition on the partition coefficient determined by the batch equilibration method
The kinetics of linuron and metribuzin decomposition in soil using different laboratory systems
Pesticide Fate and Transport throughout Unsaturated Zones in Five Agricultural Settings, USA
Pesticide transport through the unsaturated zone is a function of chemical and soil characteristics, application, and water recharge rate. The fate and transport of 82 pesticides and degradates were investigated at five different agricultural sites. Atrazine and metolachlor, as well as several of the degradates of atrazine, metolachlor, acetochlor, and alachlor, were frequently detected in soil water during the 2004 growing season, and degradates were generally more abundant than parent compounds. Metolachlor and atrazine were applied at a Nebraska site the same year as sampling, and focused recharge coupled with the short time since application resulted in their movement in the unsaturated zone 9 m below the surface. At other sites where the herbicides were applied 1 to 2 yr before sampling, only degradates were found in soil water. Transformations of herbicides were evident with depth and during the 4-mo sampling time and reflected the faster degradation of metolachlor oxanilic acid and persistence of metolachor ethanesulfonic acid. Th e fraction of metolachlor ethanesulfonic acid relative to metolachlor and metolachlor oxanilic acid increased from 0.3 to \u3e0.9 at a site in Maryland where the unsaturated zone was 5 m deep and from 0.3 to 0.5 at the shallowest depth. The flux of pesticide degradates from the deepest sites to the shallow ground water was greatest (3.0–4.9 μmol m−2 yr−1) where upland recharge or focused flow moved the most water through the unsaturated zone. Flux estimates based on estimated recharge rates and measured concentrations were in agreement with fluxes estimated using an unsaturated-zone computer model (LEACHM)
Ecology and control of blackberry (Rubus fruticosus L. agg.) V. Control by picloram granules*
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