The flux at the perfect sink boundary is a potential metric for the successful penetration of material through the cuticle proper. Plots illustrating these transitions are provided in Supplementary Figure 8. The infinite-constrained transition for the kinetic limit is inferred from the steady-state concentration at the disk’s center. We use the total steady-state surface flux as the metric for determining the infinite-constrained transition under the thermodynamic limit and the thermodynamic-kinetic transition under the infinite limit, as it is stringent and most easily determined experimentally. What limiting cases can be identified and how can we use these to understand the system?įor the case of diffusion across a finite, planar boundary, two pairs of limiting regimes exist: thermodynamic vs kinetic and infinite thickness vs constraining thickness. How does the particle-cuticle-aqueous contact angle affect the uptake for a truncated spherical particle? ![]() How does the presence of a low permeability barrier affect zero-order release from and diffusion about a particle suspended in solution? How does the geometry of this system affect the transport behavior across such a barrier?ĭoes the relative thickness of the cuticle proper affect the release from the particle and uptake under this simplified model? How does the release rate from discrete particles affect the uptake of pesticide under a zero-order kinetics release mechanism? How does release of the pesticide into the aqueous droplet, followed by partitioning into the cuticle proper, compete with release directly into the cuticle proper in terms of its contribution to the uptake? We address several key questions relevant to the overall mechanism of uptake and identify qualitative and quantitative trends for dispersed-particle formulations: We couple together the two modeling problems of diffusion across a barrier and release from a discrete particle in the context of foliar uptake into the cuticle proper. The following focuses on how the release of pesticide from particles, dispersed on the outer cuticular surface and surrounded by an aqueous medium, affects the overall diffusion of pesticide into and across the cuticle proper. (28,30) have considered truncated spheres on the cuticle boundary, their models are applied to saturated droplets rather than pesticide-carrying particles. Modeling release from non-spherical particles is often avoided in the field of controlled release from particles, (38) leaving a dearth of knowledge. ![]() Application of a model considering only one of these processes is only effective for limiting cases. These interactions are of great importance to spray-applied particulate agrochemicals and particulate contaminants. No other model accounts for the following: the hindrance of pesticide release from particles proximal to a barrier surface discrete, localized sources rather than a homogeneous solution source and competition between direct uptake into the cuticle and indirect uptake via diffusion through the solution medium. There is no model known to the authors that accounts for simultaneous release of a pesticide from a particle and its diffusion across the cuticle.
0 Comments
Leave a Reply. |