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Oxygen vacancies ( V O • • ) play a critical role as defects in complex oxides in establishing functionality in systems including memristors, all-oxide electronics, and electrochemical cells that comprise metal-insulator-metal or complex oxide heterostructure configurations. Improving oxide-oxide interfaces necessitates a direct, spatial understanding of vacancy distributions that define electrochemically active regions. We show vacancies deplete over micrometer-level distances in Nb-doped SrTiO 3 (Nb:SrTiO 3 ) substrates due to deposition and post-annealing processes. We convert the surface potential across a strontium titanate/yttria-stabilized zirconia (STO/YSZ) heterostructured film to spatial (<100 nm) vacancy profiles within STO using ( T = 500°C) in situ scanning probes and semiconductor analysis. Oxygen scavenging occurring during pulsed laser deposition reduces Nb:STO substantially, which partially reoxidizes in an oxygen-rich environment upon cooling. These results (i) introduce the means to spatially resolve quantitative vacancy distributions across oxide films and (ii) indicate the mechanisms by which oxide thin films enhance and then deplete vacancies within the underlying substrate. 

Protein-based materials provide an inherently biocompatible and sustainable platform for the generation of functional materials. Translating protein properties into protein films resistant to aqueous degradation is crucial for most applications such as tissue engineering and controlled drug delivery. Current methods to stabilize protein films use three main strategies: employing the relatively limited variety of naturally self-assembling proteins, using added cross-linkers or heat curing. While the cross-linking strategy generates functionally diverse structures, unreacted additives retained in cross-linked protein films can adversely affect their final behavior. Traditional heat curing results in hydrophobic surface and loss of protein inherent properties. We demonstrate here a scalable, additive-free, fluorous media assisted thermal treatment for the fabrication of stable, hydrophilic protein films. This approach is general in terms of protein building block, retaining much of their native structure and surface properties upon heating. We demonstrate the versatility of this strategy through fabrication of antifouling coatings on complex three-dimensional surfaces. The utility of these films as biomaterials is highlighted through the generation of highly biocompatible non-fouling surfaces and regulation of cellular adhesion through choice of protein precursor. 

Code contributions in Free/Libre and Open Source Software projects are controlled to maintain high-quality of software. Alternatives to patch-based code contribution tools such as mailing lists and issue trackers have been developed with the pull request systems being the most visible and widely available on GitHub. Is the code contribution process more effective with pull request systems? To answer that, we quantify the effectiveness via the rates contributions are accepted and ignored, via the time until the first response and final resolution and via the numbers of contributions. To control for the latent variables, our study includes a project that migrated from an issue tracker to the GitHub pull request system and a comparison between projects using mailing lists and pull request systems. Our results show pull request systems to be associated with reduced review times and larger numbers of contributions. However, not all the comparisons indicate substantially better accept or ignore rates in pull request systems. These variations may be most simply explained by the differences in contribution practices the projects employ and may be less affected by the type of tool. Our results clarify the importance of understanding the role of tools in effective management of the broad network of potential contributors and may lead to strategies and practices making the code contribution more satisfying and efficient from both contributors' and maintainers' perspectives.