Characterization of low-fouling ethylene glycol containing plasma polymer films

Low-protein-fouling poly(ethylene glycol) (PEG-like) plasma polymer films were prepared using radio frequency glow discharge polymerization of diethylene glycol dimethyl ether (DGpp) on top of a heptylamine plasma polymer primer layer. By varying the plasma deposition conditions, the chemistry of the DGpp film was influenced, especially in regard to the level of ether content, which in turn influenced the relative levels of bovine serum albumin and lysozyme protein fouling. Surface potential measurements indicated that these surfaces carried a net negative charge. While protein fouling remained low ( approximately 10 ng/cm2), there was a slightly higher level of the positively charged protein adsorbed on these films than the negative protein. The interaction forces measured between a silica spherical surface on both "high"- and "low"-protein-fouling DGpp films were all repulsive and short ranged (2-3 nm). There was no correlation between the surface forces measured for high- and low-protein-fouling DGpp films. Thus, it appears that enthalpic effects are very important in reducing protein adsorption. We therefore conclude that it is the concentration of residual, ethylene glycol containing species that are the crucial parameter determining protein resistance due to a combination of both entropic and enthalpic effects.     

Tunable laser spectroscopy of CO2 near 2.05 μm: Atmospheric retrieval biases due to neglecting line-mixing

Inclusion of line-mixing into spectroscopic models is required for precise and accurate dry-mole-fraction column CO₂ retrievals from a satellite instrument. We measure first-order line-mixing parameters of thirteen ¹²CO₂ 20⁰1₃←00⁰0 CO₂ transitions near 2.05 μm using tunable laser spectroscopy. We also report line position measurements of twelve ¹³CO₂ and ¹⁸OCO transitions in this spectral region. By incorporating line-mixing into a simple atmospheric model, we show how biases in CO₂ retrievals can be generated if line-mixing is ignored.     

Synergistic Steric Effects in the Development of a Palladium‐Catalyzed Alkyne Carbohalogenation: Stereodivergent Synthesis of Vinyl Halides

We report our finding that by exploiting the synergistic steric effects between substrate and catalyst, an intramolecular Pd‐catalyzed alkyne carbohalogenation can be achieved. This operationally simple method uses the bulky Pd/Q‐Phos combination and allows access to tetrasubstituted vinyl halides from the corresponding aryl chlorides, bromides, and iodides. Steric effects in the substrate play a key role by promoting C‐halogen reductive elimination and enabling catalytic turnover. Through a reversible oxidative addition mechanism, a thermodynamically driven isomerization reaction is observed at elevated temperatures. Thus by changing the reaction temperature, both stereoisomers of the reaction become readily accessible.     

One step multifunctional micropatterning of surfaces using asymmetric glow discharge plasma polymerization

Micropatterning of surfaces with varying chemical, physical and topographical properties usually requires a number of fabrication steps. Herein, we describe a micropatterning technique based on plasma enhanced chemical vapour deposition (PECVD) that deposits both protein resistant and protein repellent surface chemistries in a single step. The resulting multifunctional, selective surface chemistries are capable of spatially controlled protein adhesion, geometric confinement of cells and the site specific confinement of enzyme mediated peptide self-assembly.     

Microwave processing of TiO2 blocking layers for dye-sensitized solar cells

The microwave heat treatment of blocking layers for dye-sensitized solar cells has been investigated. It has been found that the solar cell efficiencies achieved with microwave heating were considerably higher than those achieved with conventional heating at low temperatures (100°C). This was attributed to microwave heating providing better sintering of the blocking layer and better interfacial contact between the substrate and the TiO₂ layers. These results are promising with regard to the application of microwave heating to the production of dye-sensitized solar cells on flexible polymer substrates.     

Remote sensing with infra-red heterodyne radiometers

The narrow spectral bandwidth capability of heterodyne radiometers can be utilized to construct highly selective pollutant sensing instruments. The infra-red spectral region is favourable due to the availability of pollutant absorption lines and the wavelength dependence of heterodyne sensitivity. We review the types of sensing systems which can make use of heterodyne techniques, including comments about the type of lasers which can serve as local oscillators. Sensitivity calculations of passive heterodyne radiometers to NO, CO₂, and SO₂ are then presented. Our concluding discussion involves the use of a heterodyne receiver in an active NO sensing system which is based on infra-red fluorescence.