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.

Right siting of complex acute wound management---preliminary study of teleconsultation wound services between acute and primary care in Singapore

This study aimed to provide preliminary evidence on feasibility of the inaugural use of teleconsultation between acute hospitals and primary care for acute wound management in Singapore. Post-surgical patients with carbuncle wounds, perianal abscess wounds or surgical abdominal dehiscence wounds were recruited from an acute hospital. Instead of receiving their follow up care at the acute care tertiary hospital, patients were given the option to receive their care at primary care facilities instead, supported by teleconsultation wound services provided by wound care nurses from the hospital. The following outcome measures were collected: number of care sessions required (until wound healed), readmissions or referrals back to hospital, cost (patient's and healthcare provider's perspective), patients' and nurses' satisfaction. In total, 18 patients were recruited and completed the study (teleconsult group = 5; tertiary care clinic group = 13). The mean age (SD) of patients were 63.2 (SD 11.5) years old in the teleconsult group and 47.9 years old (SD 11.5) in the tertiary care clinic group. There were 7 female (54%), and 6 male (46%) in the tertiary care clinic group whereas teleconsult group consisted of male only (n = 5). Most had carbuncle wounds (teleconsult group: n = 4; 80%); tertiary care clinic group: (n = 10; 77%). For patients with carbuncle wounds, the average number of care sessions required were 21 and 33 for the tertiary care clinic and teleconsult respectively. None of the patients in the teleconsult group were referred back to the tertiary care hospital. All 16 nurses (n = 6 from acute care hospital, n = 10 from polyclinics) who participated in the feedback survey cited convenience, ease of tracking wound sizes, and closer collaboration between the acute care and primary care nurses as advantages of the service. Wound teleconsultation is feasible and potentially cost savings for patients with acute complex wounds.

A flexible multiplexed immunosensor for point-of-care in situ wound monitoring

Chronic wounds arise from interruption of normal healing due to many potential pathophysiological factors. Monitoring these multivariate factors can provide personalized diagnostic information for wound management, but current sensing technologies use complex laboratory tests or track a limited number of wound parameters. We report a flexible biosensing platform for multiplexed profiling of the wound microenvironment, inflammation, and infection state at the point of care. This platform integrates a sensor array for measuring inflammatory mediators [tumor necrosis factor-α, interleukin-6 (IL-6), IL-8, and transforming growth factor-β1], microbial burden (Staphylococcus aureus), and physicochemical parameters (temperature and pH) with a microfluidic wound exudate collector and flexible electronics for wireless, smartphone-based data readout. We demonstrate in situ multiplexed monitoring in a mouse wound model and also profile wound exudates from patients with venous leg ulcers. This technology may facilitate more timely and personalized wound management to improve chronic wound healing outcomes.

P266 Infective endocarditis: exploring geographical trends and comparing risk models in a multi-ethnic asian population

Background

Host factors and complications have been associated with higher mortality in infective endocarditis (IE). We explored factors impacting mortality in our local multiracial Singapore population and validated the simplified risk score to predict 6-month mortality in IE developed by the International Collaboration on Endocarditis [ICE].

Methods

Using a retrospective registry of definite IE determined by the Duke’s criteria, we studied 116 IE cases diagnosed between January 2010 and December 2014. Baseline demographic, clinical and 6 month mortality data were collected. Logistic and Cox regression was used to study factors affecting 6 month mortality. A cut-off of p < 0.10 was used to determine factors to be put into the multivariable model.

Results

6 month mortality in the cohort was 26.7% [31/116]. Surgery during index hospitalization was performed in 20.7% [24/116] of the cohort. Significant factors affecting mortality include: [Host] diabetes mellitus, intravenous drug abuser, [IE characteristics] left sided valve regurgitation, nosocomial IE, [IE complications] persistent bacteremia, stroke and embolic phenomena. Surgery was significantly associated with lower risk of mortality.

The receiver operating curve(ROC) of the ICE simplified risk score is 0.84. Using the principle of parsimony, we compared our reduced model, removing variables (possible to state what are the variables removed to compare and contrast the 2 models) with p-value > 0.10, the ROC of our reduced model is 0.85 and difference between performance of both models were non-significant at p = 0.893. The goodness-of-fit of both models were demonstrated by non significant Hosmer-Lemeshow test. K-fold cross validation was also performed for internal validation of our reduced model.

Conclusions

6 month mortality after IE is 26.7% and is predicted by host factors, IE characteristics and complications. Surgery during the index hospitalization is associated with lower mortality. Our reduced IE model performed comparatively to the ICE risk score.

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.