Enhanced Transport of TiO2 in Unsaturated Sand and Soil after Release from Biodegradable Plastic during Composting.

Biodegradable plastics can reach full degradation when disposed of appropriately and thus alleviate plastic pollution caused by conventional plastics. However, additives can be released into the environment during degradation and the fate of these additives can be affected by the degradation process. Here, we characterized TiO2 particles released from a biodegradable plastic mulch during composting and studied the transport of the mulch-released TiO2 particles in inert sand and agricultural soil columns under unsaturated flow conditions. TiO2 particles (238 nm major axis and 154 nm minor axis) were released from the biodegradable plastic mulch in both single-particle and cluster forms. The mulch-released TiO2 particles were fully retained in unsaturated soil columns due to attachment onto the solid-water interface and straining. However, in unsaturated sand columns, the mulch-released TiO2 particles were highly mobile. A comparison with the pristine TiO2 revealed that the mobility of the mulch-released TiO2 particles was enhanced by humic acid present in the compost residues, which blocked attachment sites and imposed steric repulsion. This study demonstrates that TiO2 particles can be released during composting of biodegradable plastics and the transport potential of the plastic-released TiO2 particles in the terrestrial environment can be enhanced by compost residues.

Inactivation of Infectious Bursal Disease Virus Through Composting of Litter from Poultry Houses.

Very virulent infectious bursal disease virus (vvIBDV) was diagnosed in a pullet farm in Washington in 2014. Infectious bursal disease virus is resistant to many environmental stresses and often persists on farms for months. There have been conflicting reports as to whether composting can destroy vvIBDV in the manure. This project investigated the composting of litter from the affected house using an aerated static pile to inactivate the virus. Two weeks before the affected pullet flocks were moved to the layer house, specific-pathogen-free (SPF) birds were placed in the barns. Ten days after they were placed, three SPF birds died and were positive for vvIBDV. Thirty percent of the SPF birds were positive for vvIBDV. After the pullets were moved, at 20 wk of age, the litter in the house was composted using the aerated static pile method. The pile was maintained at above 55 C for 4 wk. After this time, 30 additional SPF birds were placed on the composted material. Two weeks later, the birds were healthy and there was no evidence of vvIBDV. The subsequent pullet flock did not break with vvIBDV. These results demonstrate that this composting method can be used to decontaminate the litter from vvIBDV and help prevent the spread of vvIBDV.

Physical stability and solubility of the thermotropic mesophase of fenoprofen calcium as pure drug and in a tablet formulation.

The aim of this study was to investigate and compare the physical stability and solubility of the liquid crystalline form of fenoprofen calcium as pure drug and in a proprietary tablet formulation (Nalfon), and to investigate if a simple heat treatment of a proprietary tablet containing fenoprofen calcium may lead to a physically stable formulation with enhanced dissolution rate and apparent solubility. The liquid crystalline form of fenoprofen calcium (thermotropic mesophase) was prepared by heating the crystalline drug to 125 degrees C to remove the water of crystallisation. Differential scanning calorimetry investigation revealed an endothermic peak at 89 degrees C upon heating (liquid crystal formation) attributable to water loss from the crystalline dihydrate. The liquid crystalline order was maintained upon cooling. No interference of tablet excipients with the thermal behaviour of the drug in the tablet formulation was observed. The crystalline dihydrate and liquid crystalline forms of fenoprofen calcium could be differentiated by diffuse reflectance infra-red spectroscopy and X-ray powder diffraction, both as pure drug and in tablet formulation. The supercooled liquid crystal (thermotropic reversed hexagonal phase) alone and in preheated and ground tablets was physically stable when stored in a dry environment or at 33% relative humidities (RH) at both 20 and 40 degrees C for 2 months. At 40 degrees C and 75% RH the supercooled mesophase extensively converted to the crystalline dihydrate within 6 days. Liquid crystalline fenoprofen calcium stored at 20 degrees C and 75% RH showed only partial dihydrate conversion after 2 months of storage. The solubility of the crystalline dihydrate alone and from the tablet formulation was 2.8+/-0.2 mg/ml and 3.0+/-0.2 mg/ml (mean+/-s.d.), respectively, (not significantly different), whereas the maximum solubility of the liquid crystal was 5.0+/-0.3 mg/ml (mean+/-s.d.) and 6.9+/-0.6 mg/ml (mean+/-s.d.), respectively (significantly different). The difference in maximum solubility between the crystalline dihydrate form of fenoprofen calcium and the fenoprofen calcium mesophase was highly significant, for both the pure drugs and the tablet formulations. The dissolution rate of the liquid crystalline fenoprofen calcium in preheated, intact tablets was significantly lower than that of the crystalline form in non-preheated tablets. Gross visual changes and scanning electron microscopy indicated that the disintegration properties of the tablet may be detrimentally effected by heating the tablet to 125 degrees C, diminishing the beneficial effect of improved solubility of the liquid crystal. The study has shown that conversion of the crystalline form of fenoprofen calcium to the liquid crystal can enhance the apparent solubility of the pure drug and the drug in presence of tablet excipients, but that the conversion should be performed before tablet formulation in order to increase dissolution of this poorly water-soluble drug.