ABSTRACT
Silver nanoparticles are produced by a novel biosynthesis technique using fungus Penicillium purpurogenum NPMF (MTCC 7356). The biomass when subjected to heat treatment up to 700 °C produces the nanoparticles of silver due to the presence of free carbon which acts as encapsulation for silver nanoparticles. Increase in temperature above 700 °C causes a reduction in concentration of free carbon so that the nanoparticles come close to each other and form clusters in the shape of tetrapods to polypods. The micro-Raman analysis supports the formation of mesoporous carbon with increase in the calcined temperature. The formation of Ag nanostructures has been explained in terms of free energy diagram i.e., the crystal favors more to grow on (100) facet or (110) facet rather than on (111) facet by the addition of silver atoms and thereby, it releases more energy. The release of energy has been confirmed from the differential thermo gravimetric analysis. In fact, it is the dynamics of the minimization of the free energy of the system which governs the reorientation and rearrangement of Ag themselves leading to formation of various types of polypods. A formation mechanism is presented schematically.
ABSTRACT
1. Frequency of Campylobacter detection was monitored in three flocks of turkeys. The effect of week of production was evaluated for hens in flocks 1 and 2, and the effect of week, gender and litter (fresh or used) was assessed for flock 3. 2. Gastrointestinal tracts, poult box liners, drinkers and faecal droppings were sampled. Conventional microbiological procedures were used to isolate and identify the presence of Campylobacter. Campylobacter latex agglutination tests were used for confirmation. 3. Peak colonisation occurred at approximately 3 weeks of production. Frequency of Campylobacter isolation from bird sources paralleled isolation from waterers. Frequency of detection from birds placed on used litter was lower than detection from birds placed on fresh litter (2% vs 58%). Gender did not affect frequency of detection. 4. Minimising peak colonisation at 3 weeks and managing litter are opportunities to reduce the occurrence of this organism in turkeys.
