Engineering Irrigation Drippers with Rechargeable N-Halamine Nanoparticles for Antifouling Applications.

The increased demand for water highlights the need to utilize reclaimed water of various types. In agriculture, for example, which is considered the largest consumer of freshwater, irrigation with treated wastewater can replace much of the need for freshwater. Wastewater is generally used for irrigation through drippers, releasing small amounts of water to the crops. The contaminants found in treated wastewater increase the accumulation of fouling on the drippers, ultimately culminating in blocking of water exit. Thus, there is a crucial need to develop novel approaches to limit biofilm formation on the dripper. Here, we describe the synthesis of N-halamine-derivatized cross-linked polymethacrylamide nanoparticles (NPs) by copolymerization of the monomer methacrylamide and the cross-linker monomer N, N-methylenebisacrylamide and their subsequent embedding in the polyethylene that is used to fabricate the drippers. The newly designed drip system was activated by chlorinating the incorporated NPs and then was fully characterized. The nanofunctionalized drippers were tested in the field, showing excellent antifouling activity for at least 5 months compared to the control. In addition, the inherent recharging capacity of the antifouling NPs constitutes yet another valuable advantage of the currently reported technology.

Development and employment of slow-release pendimethalin formulations for the reduction of root penetration into subsurface drippers.

Subsurface drip irrigation supplies water directly to the root zone and is an efficient irrigation technology. One of the main challenges is preventing plant roots from clogging the drippers. With the aim of inhibiting root penetration, slow-release pendimethalin formulations based on its solubilization in micelles adsorbed and unadsorbed to clay were developed. In the past unadsorbed micelles were considered inadequate for slow release, because release was too fast. In contrast, the advantage of a two-mode release formulation, composed of adsorbed and unadsorbed micelles, is demonstrated. A bioassay to study pendimethalin leaching at a refined scale of 1-2 cm was developed and reduced leaching from the micelle-clay formulations in comparison to the commercial formulation (Stomp) was exhibited. In a greenhouse study the application of the formulations by injection into an irrigation system was extremely efficient with 0-10% root penetration in comparison to 100% penetration upon Stomp injection.

Kinetics of two voltage-gated K+ conductances in substantia nigra dopaminergic neurons.

The substantia nigra (SN) is part of the basal ganglia which is a section in the movement circuit in the brain. Dopaminergic neurons (DA) constitute the bulk of substantia nigra neurons and are related to diseases such as Parkinson's disease. Aiming at describing the mechanism of action potential firing in these cells, the current research examined the biophysical characteristics of voltage-gated K+ conductances in the dopaminergic neurons of the SN. The outside-out configuration of the patch-clamp technique was used to measure from dopaminergic neurons in acute brain slices. Two types of K+ voltage-gated conductances, a fast-inactivating A-type-like K+ conductance (K(fast)) and a slow-inactivating delayed rectifier-like K+ conductance (K(slow)), were isolated in these neurons using kinetic separation protocols. The data suggested that a fast-inactivating conductance was due to 69% of the total voltage-gated K+ conductances, while the remainder of the voltage-gated K+ conductance was due to the activation of a slow-inactivating K+ conductance. The two voltage-gated K+ conductances were analyzed assuming a Hodgkin-Huxley model with two activation and one inactivation gate. The kinetic models obtained from this analysis were used in a numerical simulation of the action potential. This simulation suggested that K(fast) may be involved in the modulation of the height and width of action potentials initiated at different resting membrane potentials while K(slow) may participate in action potential repolarization. This mechanism may indicate that SN dopaminergic neurons may perform analog coding by modulation of action potential shape.