Listeria monocytogenes in Milk Products

peer-reviewedMilk and milk products are frequently identified as vectors for transmission of Listeria monocytogenes. Milk can be contaminated at farm level either by indirect external contamination from the farm environment or less frequently by direct contamination of the milk from infection in the animal. Pasteurisation of milk will kill L. monocytogenes, but post-pasteurisation contamination, consumption of unpasteurised milk and manufacture of unpasteurised milk products can lead to milk being the cause of outbreaks of listeriosis. Therefore, there is a concern that L. monocytogenes in milk could lead to a public health risk. To protect against this risk, there is a need for awareness surrounding the issues, hygienic practices to reduce the risk and adequate sampling and analysis to verify that the risk is controlled. This review will highlight the issues surrounding L. monocytogenes in milk and milk products, including possible control measures. It will therefore create awareness about L. monocytogenes, contributing to protection of public health

BRILLOUIN SCATTERING DETERMINATION OF THE ELASTIC MODULI OF AgGaS2 AND THEIR INFLUENCE ON THE ANALYSIS OF THE OPTICAL PHONON DATA

Les modules d'élasticité de AgGaS2 ont été déterminés par diffusion Brillouin. On trouve qu'ils sont inférieurs à ceux de l'analogue binaire ZnS. Il est discuté en détail l'intérêt que peut avoir cette observation pour attribuer des coordonnées normales aux différents phonons optiques observés. L'importance des électrons d de la configuration de Ag+ dans l'analyse des phonons optiques est également prise en considération. Sur la base de ces discussions, on suggère que les attributions précédentes peuvent être erronées pour les modes de fréquences élevées et une nouvelle attribution est proposée.The elastic moduli of AgGaS2 have been determined using laser Brillouin scattering. It is found that they are lower than those of the binary analogue ZnS. The relevance of this overall decrease in helping to assign normal mode coordinates to observed optical phonon frequencies is discussed in detail. The importance of the d-electron configuration of the Ag+ on the analysis of optical phonons is also considered. On the basis of the discussions it is proposed that the previous analyses may have been in error for high frequency modes and an alternative assignment is suggested