Anodisches Wachstum von porösen Metalloxiden und ihre Anwendungen

Metal oxide nanostructures have attracted much attention in the last decades owing to their electrical, optical and chemical properties which make them suitable for various applications such as solar cells, energy storage devices, catalytic processes etc. To form metal oxide nanostructures, several techniques have been studied namely electro/electroless deposition, atomic layer deposition, sol–gel synthesis, e-beam evaporation, magnetron sputtering and hydrothermal methods. However, these approaches have several drawbacks such as limitation of size control, separation of the individual structures, agglomeration or bundling of the structures. To overcome such a weakness of these synthesis methods, electrochemical anodization of a metal substrate to form self-organized metal oxide nanostructures has been widely studied. The self-organizing anodization approach allows an easy control on the dimensions of the anodic structures (layer thickness, pore diameter, interpore distance) and directly provides back-contacted oxides as functional electrodes. In particular, self-organized TiO2 nanotubes are the most extensively studied structures because valuable properties of TiO2, like semiconductive behavior, photocatalytic and photoelectrochemical properties, can be enhanced by controlling their geometry. In order to form self-organized TiO2 nanotube structures, the anodization is mostly carried out in fluoride ion-containing electrolytes. By controlling the anodization conditions, the morphology of TiO2 nanotubes can be tuned. Furthermore, in fluoride-free electrolyte (for example, hot glycerol/K2HPO4 electrolytes) other types of TiO2 nanostructures can be formed, such as mesoporous and nanochannel structures. However, detailed investigations about the mechanism of formation of self-organized anodic TiO2 nanostructures in such an electrolyte have not been performed yet. In this context, the preset thesis focuses on revealing the critical anodization conditions to form various TiO2 nanostructures in fluoride-containing and fluoride-free electrolytes. Based on the acquired knowledge, the self-organizing anodization approaches are extended to other promising materials like Ta, Nb and W. Furthermore, well-defined metal oxide nanostructures shown in this thesis are used for several promising applications.Metalloxidnanostrukturen haben auf Grund ihrer elektrischen, optischen und chemischen Eigenschaften für verschiedene Anwendungen über Jahrzente hinweg große Aufmerksamkeit auf sich gezogen. Für die Herstellung der Metalloxidnanostrukturen wurden verschiedene Verfahren, wie galvanische/stromlose Abscheidung, Atomlagenabscheidung, Sol-Gel, Elektronenstrahlverdampfung, Magnetron-Sputtern, hydrothermale Verfahren und Andere untersucht. Jedoch bringen diese Methoden auch einige Nachteile wie limitierte Größenkontrolle, Agglomeration oder Bündelung der Strukturen mit sich. Die deutlich einfachste Weise ist die anodische Oxidation auf Metallsubstraten zur Bildung von Metalloxidnanostrukturen, bei der die Dimension (Länge, Durchmesser) und der direkte Rückkontakt kontrolliert werden können. Insbesondere können durch das Anodisationsverfahren selbstorganisierte eindimensionale Nanostrukturen hergestellt werden, die eine hohe spezifische Oberfläche und vermutlich gerichtete Elektronenpfade besitzen. Die selbstorganisierten anodischen Metalloxidstrukturen wurden über Jahrzehnte hinweg studiert. Besonders hexagonal gepacktes, poröses Aluminiumoxid hat durch die anodische Bildung von selbstorganisierten porösen Strukturen Aufmerksamkeit auf sich gezogen. Speziell anodisch hergestellte selbstorganisierte TiO2 Nanostrukturen wurden auf Grund ihrer halbleitenden, ungiftigen Eigenschaften und chemischen Stabilität intensiv untersucht. Das am häufigsten gebrauchte Verfahren zur Herstellung von TiO2 Nanostrukturen ist die Verwendung von fluoridhaltigen Elektrolyten. In solchen Elektrolyten können weitere verschiedene Metallsubstrate sowie Metalllegierungen zu selbstorganisierten Nanostrukturen umgewandelt werden. Um solche wohldefinierten Nanostrukturen herzustellen sind eingehende Untersuchungen nötig. In diesem Zusammenhang wird der Schwerpunkt dieser Arbeit auf das Ermitteln der entscheidenden Anodisationsbedingungen zur Bildung von Nanostrukturen gelegt. Zunächst werden die kritischen Einflussgrößen für die Herstellung selbstorganisierter TiO2 Nanostrukturen durch die elektrochemische Anodisation von Titansubstraten in verschiedenen (fluoridhaltigen oder fluoridfreien) Elektrolyten beschrieben. Die TiO2 Nanostrukturen besitzen einzigartige Eigenschaften, die von den Anodisationsbedingungen abhängen. Zweitens werden in dieser Arbeit die möglichen Anwendungen, wie Solarzellen, Photokatalysatoren und Ionenspeicher erforscht. Zum Schluss wird gezeigt, dass neuartige Anodisationsverfahren mit fluorionenhaltigen Elektrolyten (wie zum Beispiel heißes Glycerin/K2HPO4 Elektrolyten) auf andere wichtige Materialien wie Ta, Nb und W übertragen werden können. Diese Metalle können zu hochgeordneten Nanokanälen oder nanoporösen Strukturen umgewandelt werden, die spezifische photoelektrochemische und elektrochemische Eigenschaften aufweisen

Protein Interactome and Its Application to Protein Function Prediction

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Characterization of urinary cotinine in non-smoking residents in smoke-free homes in the Korean National Environmental Health Survey (KoNEHS)

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Abstract Background The objectives of this study were to determine urinary cotinine concentrations in non-smoking residents of smoke-free homes and to establish the relationship of urinary cotinine with housing type and other socio-demographic and secondhand smoke (SHS) exposure factors. Methods We used data from the Korean National Environmental Health Survey I (2009–2011). The study included 814 non-smoking adult residents living in apartments, attached, and detached housing. Residents who lived with smokers were excluded. Urinary cotinine concentration was used as a biomarker for SHS exposure. The factors associated with urinary cotinine levels in non-smoking residents were determined using multivariate regression analysis. Results Urinary cotinine was detected in 88 % of the 814 non-smoking residents of smoke-free homes. The urinary cotinine concentrations of residents living in attached [1.18 ng/mg creatinine (Cr)] and detached housing (1.23 ng/mg Cr) were significantly higher than those of residents who lived in apartments (0.69 ng/mg Cr). Urinary cotinine concentrations were significantly higher in residents who were men, those with a household income ≤1000 USD/month, those who were former smokers with >1 year and ≤1 year of not smoking, and those who experienced SHS odor every day. In the multivariate regression analysis, housing type, sex, former smoking status, and frequency of experiencing SHS odor were associated with urinary cotinine concentrations (R 2 = 0.14). Conclusions The majority of non-smoking residents of smoke-free homes had detectable urinary cotinine. Housing type, sex, former smoking status, and frequency of experiencing SHS odor were predictors for urinary cotinine concentrations in the study participants

Photoelectrochemical Properties of Anodic TiO2 Nanosponge Layers

In the present work we grow TiO2 nanosponge structures by anodizing Ti in a glycerol/water/NH4F electrolyte to thickness of some mu m. We evaluate the photoelectrochemical behavior (bandgap, photocurrent-voltage characteristics) in presence and absence of methanol. Methanol drastically affects the photoresponse (due to hole capture and current doubling). The optimum thickness for photoelectrochemical applications of these nanostructures is dependent on the excitation wavelength. For applications such as solar light water splitting, anodic sponge structure of approximate to 500 nm thickness can be beneficially used to increase the photoresponse compared to compact TiO2 layers.The authors would like to express their gratitude to the Spanish Ministry of Science and Innovation FPU grant given to Rita Sanchez Tovar, as well as DFG, and the DFG Cluster of Excellence (EAM) at the University of Erlangen-Nuremberg for financial support.Sánchez Tovar, R.; Lee, K.; Garcia-Anton, J.; Schmuki, P. (2013). Photoelectrochemical Properties of Anodic TiO2 Nanosponge Layers. ECS Electrochemistry Letters. 2(3):9-11. doi:10.1149/2.005303eelS9112

Conquest of the ghost pyramid of the superstring

We give a new Becchi-Rouet-Stora-Tyutin operator for the superstring. It implies a quadratic gauge-fixed action, and a new gauge-invariant action with first-class constraints. The infinite pyramid of spinor ghosts appears in a simple way through ghost gamma matrices.Comment: 30 pages, 1 figure, Late

Factors associated with secondhand smoke incursion into the homes of non-smoking residents in a multi-unit housing complex: a cross-sectional study in Seoul, Korea

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Abstract Background In a multi-unit housing (MUH) complex, secondhand smoke (SHS) can pass from one living space to another. The aim of this study was to determine the prevalence of SHS incursion, and to establish the relationship between SHS incursion and socio-demographic and built environmental factors in MUH in Korea. Methods A population-based sample of 2600 residents (aged ≥19 years) living in MUH from across the city of Seoul, Korea, was obtained through a web-based selection panel. The residents completed a questionnaire detailing socio-demographic factors, smoking status, frequency of SHS incursion, and built environmental factors. The presence of a personal smoke-free home rule was determined by residents declaring that no one smoked inside the home. Results Of the 2600 participants, non-smoking residents who lived in homes with a personal smoke-free rule were selected for further analysis (n = 1784). In the previous 12 months, 74.7% of residents had experienced SHS incursion ≥1 times. A multivariate ordinal logistic regression analysis indicated that residents who spent more time at home, lived with children, supported the implementation of smoke-free regulations in MUH, lived in small homes, lived in homes with natural ventilation provided by opening a front door or the windows and front door, and lived in homes with more frequent natural ventilation were more likely to report SHS incursion into their homes. Conclusions The majority of the non-smoking residents experienced SHS incursion, even with a personal smoke-free rule in their homes. A smoke-free policy in MUH is needed to protect residents from SHS exposure when they are at home