Mathematical Fate Modeling Of Hazardous Organic Pollutants During Codisposal With Municipal Refuse

A mathematical mass transport model, the Vadose Zone Interactive Processes model, was employed to describe the fate of organic compounds codisposed in municipal refuse landfills. The model solves a convective-dispersive equation which incorporates transport and transformation processes of dispersion, advection, chemical and biological transformation, and sorption in unsaturated porous media. Using input data selected to describe laboratory refuse column operations and the operative physical/chemical phenomena, the predictive capabilities of the model were optimized. Test compounds included 12 organic compounds representing a broad range of organic classes. The mathematical model accurately predicted low mobility of hydrophobic compounds and described the migration of more hydrophilic test compounds in municipal refuse

The Fate Of Selected Organic Pollutants Codisposed With Municipal Refuse

Twelve compounds, representing major organic classes, were codisposed with municipal refuse waste using laboratory-scale refuse columns. The mobility of soluble, hydrophilic compounds was observed as a function of the affinity of these compounds for the refuse. Transport to column headspaces was detected for more volatile compounds. Hydrophobic compounds displayed little movement down the columns. Behavior of the compounds could be predicted using experimental linear isotherm partition coefficients. The results of this investigation provided a mechanistic evaluation of the attenuating capacity of municipal landfills for specific organic compounds

Studying axonal outgrowth and regeneration of the corticospinal tract in organotypic slice cultures

Studies of axonal outgrowth and regeneration after spinal cord injury are hampered by the complexity of the events involved. Here we present a simple and improved in vitro approach to investigate outgrowth, regeneration of the corticospinal tract and intrinsic parenchymal responses. We prepared organotypic co-cultures using explants from the motor cortex of postnatal donor mice, ubiquitously expressing green fluorescent protein, and cervical spinal cord from wild type pups of the same age. Our data show that a) motor-cortical outgrowth is already detectable after one day in culture and is source specific; b) treatment with neurotrophin-3 and C3 transferase from Clostridium botulinum significantly enhances axonal outgrowth during the course of cultivation; c) outgrowing axons form synaptic connections, as demonstrated by immunohistochemistry and calcium imaging; and d) migrating cells of motor-cortical origin can be reliably identified without previous tracing and are mostly neural precursors that survive and mature in the spinal cord parenchyma. Thus, our model is suitable for screening for candidate substances that enhance outgrowth and regeneration of the corticospinal tract and for studying the role of endogenous neural precursors after lesion