Evaluation of antimicrobial coatings in wet conditions and development of sulphonated poly (ether ether ketone) - copper composites for antimicrobial applications

The existence of pathogenic bacteria and fungi on surfaces can be a serious threat to health causing numerous infections. With microorganisms developing antimicrobial resistance over the years, there is an increasing need to develop surfaces that can kill or inhibit the growth of bacteria and fungi. Antimicrobial coatings have been tested as an effective solution to battle hospital-acquired infections, which are one of the leading causes for patient morbidity and mortality. Aereus Technologies has been working on developing a coating consisting of marine paint and biocidal copper-alloy based microparticles that can render surfaces antimicrobial. One of the key concerns for this new coating is that the microparticles are expected to oxidize when exposed to human palm sweat or disinfection agents in healthcare settings. To investigate this possibility, the antimicrobial efficacy and durability of this coating was evaluated under exposure to different saline environments (artificial ocean water and artificial sweat environment) and a strongly oxidizing environment (hydrogen peroxide). From the experiments, it was observed that regular painted and marine painted samples with proprietary “Aereus shield” particles have the ability to survive harsh oxidizing conditions without losing their antimicrobial properties. The antimicrobial application of copper was extended to the synthesis of sulphonated poly (ether ether ketone) (SPEEK) and copper composite films as promising antimicrobial materials. The effects of fabricating surface structures (micro-pillars) on the films were investigated. The synthesized films were systematically characterized and it was observed that both SPEEK and SPEEK – Cu films possessed antimicrobial properties which initially demonstrated over 4 log reduction of E. coli within 15 minutes of contact. Over longer times as the films aged, the SPEEK – Cu film still achieved over 2 log (for flat film) and 4 log (for micro-pillared film) reduction of E. coli within 1 hour of contact and showed significant fungal growth reduction for Saccharomyces cerevisiae (yeast) and Aspergillus niger after 2 hours of contact. Micro-pillared films had a larger water contact angle (131°) in comparison to flat films (64°), indicating that they were hydrophobic. These micro-pillared films also showed better antimicrobial properties and more copper release than flat films, due to better exposure of copper particles on the top surface of the micro-pillars. The synthesized films were also thermally stable up to 300°C and exhibited tensile strengths ranging from 50 – 160 MPa depending on the surface morphology and copper content. Furthermore, the films were found to be recyclable by dissolution in sulphuric acid and re-casting to form new films with replenished sulphonic acid groups in the polymer matrix and restored antimicrobial properties

The mealybug chromosome system I: unusual methylated bases and dinucleotides in DNA of a Planococcus species

The methylation status of the nuclear DNA from a mealybug, a Planococcus species, has been studied. Analysis of this DNA by High Performance Liquid Chromatography and Thin Layer Chromatography revealed the presence of significant amounts of 5--methylcytosine. Since analysis of DNA methylation using the Msp I/Hpa II system showed only minor differences in susceptibility of the DNA to the two enzymes, it seemed possible that 5-methylcytosine (5mC) occurred adjacent to other nucleotides in addition to its usual position, next to guanosine. This was verified by dinucleotide analysis of DNA labelledin vitro by nick translation. These data show that the total amount of 5-methylcytosine in this DNA is slightly over 2.3 mol %, of which 0.61% occurs as the dinucleotide 5mCpG, 0.68% as 5mCpA, 0.59% as 5mCpT and 0.45% as 5mCpC. 5mCpG represents approximately 3.3% of all CpG dinucleotides. The experimental procedure would not have permitted the detection of 5mCp5mC, if it occurs in this system. Unusually high amounts of 6-methyladenine (approximately 4 mol %) and 7-methylguanine (approximately 2 mol %) were also detected, 6-methyladenine and 7-methylguanine occurred adjacent to all four nucleotides. The total G+C content was 33.7% as calculated from dinucleotide data and 32.9% as determined from melting profiles

Handling Location Uncertainty in Event Driven Experimentation

Singapore National Research Foundation under International Research Centre @ Singapore Funding Initiativ

myDeal: A Mobile Shopping Assistant Matching User Preferences to Promotions

National Research Foundation (NRF) Singapore under International Research Centre @ Singapore Funding Initiativ

myDeal: The Context-Aware Urban Shopping Assistant

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Spatiotemporal Compound Wavelet Matrix Framework for Multiscale/Multiphysics Reactor Simulation: Case Study of a Heterogeneous Reaction/Diffusion System

We present a mathematical method for efficiently compounding information from different models of species diffusion from a chemically reactive boundary. The proposed method is intended to serve as a key component of a multiscale/ multiphysics framework for heterogeneous chemically reacting processes. An essential feature of the method is the merging of wavelet representations of the different models and their corresponding time and length scales. Up-and-downscaling of the information between the scales is accomplished by application of a compounding wavelet operator, which is assembled by establishing limited overlap in scales between the models. We show that the computational efficiency gain and potential error associated with the method depend on the extent of scale overlap and wavelet filtering used. We demonstrate the method for an example problem involving a two-dimensional chemically reactive boundary and first order reactions involving two species