Developing high intensity ultrasonic cleaning (HIUC) for post-processing additively manufactured metal components.

The high energy phenomenon of cavitation bubble collapses has enabled numerous applications, including cleaning. In ultrasonic cleaning, cavitation intensity is typically lower than in other applications, such as sonochemistry and material processing. However, there has been an emerging application in intense cleaning of metal additively manufactured (AM) components. The presence of partially melted powders on AM surfaces is undesirable, contributing to high surface roughness and posing contamination risks during usage. We designed a high-intensity cavitation cleaning process that has significantly higher inertial cavitation intensity - i.e., erosion potential - than a conventional ultrasonic cleaning tank. Through acoustic signal characterisation, we showed that placing transducer sets on four sides of the tank could effectively focus and generate high-amplitude pressure waves directed towards the central region. Strong subharmonic signals indicate intensely inertial cavitation throughout the tank. Cavitation intensities were measured at various locations to understand the wave transmission characteristics and distribution patterns. Our results show that the cavitation intensity distribution is highly dependent on the height position. Finally, we demonstrated that the high intensity ultrasonic cleaning (HIUC) process could remove partially melted powders from an AM surface - which was not possible through conventional ultrasonic cleaning. HIUC could lead to higher cleaning efficiency and enhanced AM specimen cleanliness.

Seroprevalence and molecular detection of leptospirosis from a dog shelter.

A study on seroprevalence and molecular detection of canine leptospirosis was carried out in a dog population (randomly selected n=80 dogs) from an animal shelter X. All the dogs in Shelter X appeared clinically healthy. Eighty blood samples were obtained and their serum were serologically examined using Microscopic Agglutination Test (MAT) against 10 Leptospira serovars. Plasma samples obtained were subjected to Polymerase Chain Reaction (PCR) assay. Three out of 80 dogs (3.8%) tested positive for L. bataviae based on MAT at a titer of 1:80. The seroprevalence of 9 other Leptospira serovars was not evident in this study. All the dogs tested negative against leptospirosis with PCR assay. In conclusion, canine leptospirosis was detected in dogs in this animal shelter. L. bataviae was identified as the infecting serovar. To our knowledge, this is the second report of serovar Bataviae infection in dogs in Malaysia. The 3 dogs in our study could possibly be a source of leptospiral infection to other dogs and may shed the bacteria into the environment. This serovar is not available in canine vaccination programs, therefore the dogs are not protected from this disease. Further investigation is warranted to determine whether the infected dogs are carriers of this serovar.