Flexible Transparent Barrier Applications of Oxide Thin Films Prepared by Photochemical Conversion at Low Temperature and Ambient Pressure

Photoconversion of metal-organic precursors to thin film metal oxides using ultraviolet (UV) radiation in oxidative atmosphere is an attractive technology because it can be applied at temperatures <80°C and at ambient pressure. Thus, it enables preparing this class of thin films in a cost-efficient manner on temperature sensitive substrates such as polymer films. In this article, various aspects of research and development in the field of photochemical thin-film fabrication, with particular focus to the application of the produced films as gas permeation barriers for the encapsulation of optoelectronic devices are reviewed. Thereby, it covers investigations on fundamental photochemically initiated reactions for precursor classes containing metal-oxygen and metal-nitrogen bonds, and emphazises the relevance of that understanding for applicative considerations like integration of the single-layer barrier films into relevant encapsulation films. Further perspectives are given concerning integration of additional functionalities like electrical conductivity to the flexible and transparent barrier films. © Copyright © 2020 With, Helmstedt and Prager

Probing the magnetic properties of [MnIII6CrIII]3+ single-molecule magnets by XAS, XMCD and spin-resolved electron spectroscopy

Helmstedt A. Probing the magnetic properties of [MnIII6CrIII]3+ single-molecule magnets by XAS, XMCD and spin-resolved electron spectroscopy. Bielefeld: Bielefeld University; 2014

Closed graph theorems for locally convex topological vector spaces

A Dissertation Submitted of the Faculty of Science, University of the Witwatersrand, Johannesburg in Partial Fulfilment of the Requirements for the Degree of Master of ScienceLet 4 be the class of pairs of loc ..My onvex spaces (X,V) “h ‘ch are such that every closed graph linear ,pp, 1 from X into V is continuous. It B is any class of locally . ivex l.ausdortf spaces. let & w . (X . (X.Y) e 4 for ,11 Y E B). " ‘his expository dissertation, * (B) is investigated, firstly i r arbitrary B . secondly when B is the class of C,-complete paces and thirdly whon B is a class of locally convex webbed s- .ce

Functionalized and Platinum-Decorated Multi-Layer Oxidized Graphene as a Proton, and Electron Conducting Separator in Solid Acid Fuel Cells

In the present article, electrodes containing a composite of platinum on top of a plasma-oxidized multi-layer graphene film are investigated as model electrodes that combine an exceptional high platinum utilization with high electrode stability. Graphene is thereby acting as a separator between the phosphate-based electrolyte and the platinum catalyst. Electrochemical impedance measurements in humidified hydrogen at 240 °C show area-normalized electrode resistance of 0.06 Ω·cm−2 for a platinum loading of ∼60 µgPt·cm−2, resulting in an outstanding mass normalized activity of almost 280 S·mgPt−1, exceeding even state-of-the-art electrodes. The presented platinum decorated graphene electrodes enable stable operation over 60 h with a non-optimized degradation rate of 0.15% h−1, whereas electrodes with a similar design but without the graphene as separator are prone to a very fast degradation. The presented results propose an efficient way to stabilize solid acid fuel cell electrodes and provide valuable insights about the degradation processes which are essential for further electrode optimization

Aligning biodiversity conservation and agricultural production in heterogeneous landscapes

Understanding the trade-offs between biodiversity conservation and agricultural production has become a fundamental question in sustainability science. Substantial research has focused on how species’ populations respond to agricultural intensification, with the goal to understand whether conservation policies that spatially separate agriculture and conservation or, alternatively, integrate the two are more beneficial. Spatial heterogeneity in both species abundance and agricultural productivity have been largely left out of this discussion, although these patterns are ubiquitous from local to global scales due to varying land capacity. Here, we address the question of how to align agricultural production and biodiversity conservation in heterogeneous landscapes. Using model simulations of species abundance and agricultural yields, we show that trade-offs between agricultural production and species’ abundance can be reduced by minimizing the cost (in terms of species abundance) of agricultural production. We find that when species’ abundance and agricultural yields vary across landscapes, the optimal strategy to minimize trade-offs is rarely pure land sparing or land sharing. Instead, landscapes that combine elements of both strategies are optimal. Additionally, we show how the reference population of a species is defined has important influences on optimization results. Our findings suggest that in the real world, understanding the impact of heterogeneous land capacity on biodiversity and agricultural production is crucial to designing multi-use landscapes that jointly maximize conservation and agricultural benefits.Fil: Butsic, Van. University of California at Berkeley; Estados Unidos. Berkeley University; Estados UnidosFil: Kuemmerle, Tobias. Universität zu Berlin; AlemaniaFil: Pallud, Leo. ENSTA ParisTech; FranciaFil: Helmstedt, Kate J.. Queensland University of Technology; AustraliaFil: Macchi, Leandro. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina. Universität zu Berlin; AlemaniaFil: Potts, Matthew D.. University of California at Berkeley; Estados Unido

Cost-efficient fenced reserves for conservation: single large or two small?

Fences that exclude alien invasive species are used to reduce predation pressure on reintroduced threatened wildlife. Planning these continuously managed systems of reserves raises an important extension of the Single Large or Several Small (SLOSS) reserve planning framework: the added complexity of ongoing management. We investigate the long-term cost-efficiency of a single large or two small predator exclusion fences in the arid Australian context of reintroducing bilbies Macrotis lagotis, and we highlight the broader significance of our results with sensitivity analysis. A single fence more frequently results in a much larger net cost than two smaller fences. We find that the cost-efficiency of two fences is robust to strong demographic and environmental uncertainty, which can help managers to mitigate the risk of incurring high costs over the entire life of the project

Low-temperature atmospheric pressure plasma conversion of polydimethylsiloxane and polysilazane precursor layers to oxide thin films

We study the conversion of two polymeric silicon precursor compound layers (perhydropolysilazane and polydimethylsiloxane) on a silicon wafer and polyethylene terephthalate substrates to silicon oxide thin films using a pulsed atmospheric pressure plasma jet. Varying the scan velocity and the number of treatments results in various film compositions, as determined by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The mechanism suggested for the conversion process includes the decomposition of the precursor triggered by plasma-produced species, the oxidation of the surface, and finally, the diffusion of oxygen into the film, while gases produced during the precursor decomposition diffuse out of the film. The latter process is possibly facilitated by local plasma heating of the surface. The precursor conversion appears to depend sensitively on the balance between the different contributions to the conversion mechanism

Heptanuclear [FeIII6CrIII]3+ Complexes Experimentally Studied by Means of Magnetometry, X-ray Diffraction, XAS, XMCD and Spin-Polarized Electron Spectroscopy in Cross-Comparison with [MnIII6CrIII]3+ Single-Molecule Magnets

Dohmeier N, Helmstedt A, Müller N, et al. Heptanuclear [FeIII6CrIII]3+ Complexes Experimentally Studied by Means of Magnetometry, X-ray Diffraction, XAS, XMCD and Spin-Polarized Electron Spectroscopy in Cross-Comparison with [MnIII6CrIII]3+ Single-Molecule Magnets. Magnochemistry. 2016;2(1): 5

Scrutinizing the impact of policy instruments on adoption of agricultural conservation practices using Bayesian expert models

Policy instruments—such as regulation, financial incentives, and agricultural extension—are commonly applied by governments to promote sustainable agricultural practices and tackle ecosystem degradation. Despite substantial investment, little data are available to gauge the impact of evolving policy mixes. We constructed a Bayesian network model to explore relationships between pol-icy instruments, contextual factors, and adoption. Applying a series of scenarios, we present examples of how different instruments influence adoption and how their effectiveness is shaped by contextual factors. Scenarios highlight that the effect of policy instruments is often modest, and constrained by diverse practice and population characteristics. These findings allow us to reflect on the role of policy instruments, and the conditions necessary to support practice change. For example, our findings raise questions about the role of financial benefits versus financial capacity, and highlight the potential importance of concepts such as mental bandwidth in shaping both motivation and capacity to adopt