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Class of 2016 Abstract and Report / Objectives: To describe the effect of time spent in pneumatic tube system on the concentrations of bags of regular insulin. Methods: Twelve intravenous bags of regular insulin in normal saline with a concentration of one unit per milliliter were prepared, with six bags acting as the control group and six bags as the experimental group. Bags in the experimental group were transported to stations labeled X, Y, and Z which were at varying distances from the pharmacy. Bags in the control group were walked the same tube stations. Three samples from each bag were analyzed using the ValiMed™ medication validation system before and after transport and the standard deviations (SDs) from the mean were recorded. Results: At baseline there were no statistically significant differences in the standard deviations (SDs) between the control and experimental group (p = 0.1008). SDs after transport compared to baseline SDs produced statistically significant differences (p < 0.005) except for the control group transported to tube station Z (p = 0.0867). Conclusions: The SDs after either transport produced a statistically significant difference when compared to baseline except for one group of insulin bags. This indicates that concentration may not be affected by method of delivery, since statistically significant difference occurred regardless of transport method. It appears to be safe to transport insulin IV infusion bags by pneumatic tube system.

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The aim of this study was to observe biofilm formation by Enterobacter sakazakii (E. Sakazakii) from different clinical, dairy and environmental origins on three infant feeding tubes made of different materials. Infant formula milk was selected as the medium for E. sakazakii growth. Seventeen isolates from different origins were retrieved and tested for purity, using a plating method and biochemical tests to eliminate the non E. sakazakii strains from this study. A method to rapidly and accurately detect viable cells of E. sakazakii on infant feeding tube surfaces using of the BacTrac® 4000 microbiological growth analyser was developed. The sources of errors such as from cleaning, operation and handling procedures were assessed prior to experimental runs. The strength of biofilm formation by different isolates of E. sakazakii on plastic surfaces was scrutinised using a microtiter plate assay. The results from the microtitre plate assay were based on the absorbance at 550 nm of crystal violet stained films and showed that all the clinical isolates were able to attach and form strong biofilms on the plate. Some environmental isolates formed strong or weak biofilms and some did not produce biofilm at all. However, dairy isolates formed both strong and weak biofilms in the microtitre plate when incubated in 10% reconstituted infant formula milk. The further studies were to quantify biofilm formation by three isolates of different origin on three different materials of infant feeding tubes using a batch system. Tubing pieces were incubated with infant formula milk inoculated with E. sakazakii cells at approximately 8 log CFU mL-1 and the biofilm formation was assessed at three time intervals: 4, 12 and 24 hours. Biofilm formation on the tubing by clinical isolates was also observed using epifluorescence microscopy and the scanning electron microscope. E. sakazakii from clinical, dairy and environmental isolates were able to form biofilm on three different materials of infant feeding tubes. The results showed that the initial attachment at 4 h on silicone tubing was low compared with the other two tubes. The scanning electron micrographs showed the surface characteristics of each tubing and the biofilm formation by E. sakazakii clinical isolates after 4, 12 and 24 hours. Silicone tubing appeared to be the best choice for premature babies that need feeding using feeding tubes, as it was slow to become colonised compared with the PVC and polyurethane tubing.

Valve wear has been a serious problem to engine designers and manufacturers for many years. Although new valve materials and production techniques are constantly being developed, these advances have been outpaced by demands for increased engine performance. The drive for reduced oil consumption and exhaust emissions, the phasing out of leaded petrol, reductions in the sulphur content of diesel fuel and the introduction of alternative fuels such as gas all have implications for valve and seat insert wear. The aim of the project has been, through the use of a representative bench test and engine testing, to diagnose the predominant wear mechanisms in diesel engine inlet valves and seats. This information was then to be used with other test data to develop a model for predicting valve recession and other tools to assist in solving valve failure problems. Test apparatus has been developed that is capable of providing a simulation of the wear of both inlet valves and seats used in automotive diesel engines. Investigations carried out using the apparatus have shown that the valve and seat wear problem involves two distinct mechanisms; impact of the valve on the seat insert on valve closure and sliding of the valve on the seat under the action of the combustion pressure. Wear has been shown to increase with valve closing velocity, combustion load and misalignment of the valve relative to the seat. Lubrication of the valve/seat interface leads to a significant reduction in valve recession. Valve rotation ensures even wear and promotes debris removal from the valve/seat interface. During testing it was established that resistance to impact was the key seat material property determining the amount of recession that occurred. A semi-empirical wear model for predicting valve recession has been developed based on the fundamental mechanisms of wear determined during test work. Model predictions were compared with engine tests and tests run on the bench test-rig. The model can be used to give a quantitative prediction of the valve recession to be expected with a particular material pair or a qualitative assessment of how parameters need to be altered in order to reduce recession. Flow charts have also been developed, based on the review of literature, failure analysis and modelling carried out, to assist in diagnosing and rectifying valve/seat failures and to help in reducing valve recession by design. The test apparatus, valve recession model and design tools can be integrated into an industrial environment in order to help reduce costs and timescales involved in solving valve/seat wear problems using the current trial and error methods.

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