@incollection{HenkelHaeberleMuelleretal., author = {Henkel, Karsten and Haeberle, J{\"o}rg and M{\"u}ller, Klaus and Janowitz, Christoph and Schmeißer, Dieter}, title = {Preparation, properties and electronic structure of SnO₂}, series = {Single Crystals of Electronic Materials}, booktitle = {Single Crystals of Electronic Materials}, editor = {Fornari, Robert}, publisher = {Elsevier, Woodhead Publishing}, address = {Duxford}, isbn = {978-0-08-102096-8}, pages = {547 -- 572}, abstract = {This chapter reports about tin oxide (SnO₂), a material which belongs to the transparent conducting oxide family and is best characterized by its high conductivity, high carrier mobility, and the ability to form p-type conductivity. We correlate these properties in terms of localized intrinsic electronic defect states which are resolved by resonant photoelectron spectroscopy measurements. We describe SnO₂ in terms of an inhomogeneous, mixed-ionic-covalent semiconductor in which these intrinsic electronic defects state are stabilized.}, language = {en} } @misc{MuellerRachowGuentheretal., author = {M{\"u}ller, Klaus and Rachow, Fabian and G{\"u}nther, Vivien and Schmeißer, Dieter}, title = {Methanation of Coke Oven Gas with Nickel-based catalysts}, series = {International Journal of Environmental Science}, journal = {International Journal of Environmental Science}, number = {4}, issn = {2367-8941}, pages = {73 -- 79}, abstract = {For a complete transition from fossil to CO₂ neutral energy supply new energy storage concepts are needed that allow energy supply in times of absence of regenerative power production as during dark doldrums. A promising renewable energy storage approach is the power to gas (to power) technique based on the production of synthetic natural gas (also called e-methane) by methanation of CO₂ with H₂. The latter is usually produced by electrolysis. In any power to gas concept, electrolysis is a very critical part, due to its high costs, stability issues, or limited power of required electrolysers. As an alternative source of hydrogen, we investigate the methanation of coke oven gas (COG). COG is a byproduct of the carbon rich coke production from coal for the steel industry, with a high amount of hydrogen (~60vol\%). Coke oven gas furthermore contains CH₄(~25vol\%), CO (5-8vol\%), and CO₂(1-3vol\%), making it an attractive feedstock for the production of synthetic energy carriers like methane. In the present study, the authors investigate the direct conversion of CO and CO₂ from COG into e-methane. Compared to stoichiometric conversion, the COG hydrogen content is too high for catalytic methanation of CO₂. In order to achieve a higher methane yield, the addition of CO₂ from air, flue gas, or coal gasification can compensate the surplus of hydrogen in the coke oven gas. The process is evaluated by the conversion of CO and CO₂, the catalyst selectivity towards higher hydrocarbons for varying temperatures, and the CH₄ yield.}, language = {en} } @misc{KotHenkelMuelleretal., author = {Kot, Małgorzata and Henkel, Karsten and M{\"u}ller, Klaus and Kegelmann, Lukas and Albrecht, Steve and Tsud, Nataliya and K{\´u}s, Peter and Matolinov{\´a}, Iva and Schmeißer, Dieter}, title = {Al2O3-Atomic Layer Deposited Films on CH3NH3PbI3 : Intrinsic Defects and Passivation Mechanisms}, series = {Energy Technology , The Journal of Physical Chemistry C}, volume = {7}, journal = {Energy Technology , The Journal of Physical Chemistry C}, number = {11}, issn = {2194-4288}, doi = {10.1002/ente.201900975}, pages = {10}, abstract = {The initial interaction of atomic layer deposited films of Al2O3 at room temperature on CH3NH3PbI3 (MAPI) films is studied. Synchrotron radiation-based photoelectron spectroscopy is applied to analyze the initial changes in the Al-derived features by comparing samples with different Al2O3 film thicknesses. It is found that polarons and excitons, both intrinsic defects of Al2O3, play a key role in the interface formation. The polaronic states uptake a charge from the MAPI substrate. This charge is transferred to and stabilized in the excitonic state of Al2O3 which is assigned to predominately tetrahedral coordinated Al sites. This charge transfer is initiated by vacancies present in the MAPI substrate and stabilizes a covalent bonding at the Al2O3-MAPI interface but also causes a roughening of the interface which may lead to the formation of grain boundaries. On top of the rough interface, 2D Al2O3 clusters with an increasing number of octahedrally coordinated Al—O bonds grow, and with increasing Al2O3 coverage, they introduce self-healing of the structural defects.}, language = {en} } @incollection{MuellerIsraelRachowetal., author = {M{\"u}ller, Klaus and Israel, Johannes and Rachow, Fabian and Schmeißer, Dieter}, title = {Sabatier-Based Direct Synthesis of Methane and Methanol Using CO2 from Industrial Gas Mixtures}, series = {Engineering Solutions for CO2 Conversion}, booktitle = {Engineering Solutions for CO2 Conversion}, editor = {Ramirez Reina, Tomas and Odriozola, Jos{\´e} Antonio and Arellano-Garc{\´i}a, Harvey}, edition = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-34639-4}, pages = {253 -- 280}, language = {en} } @misc{HeitmannGlemnitzBirkhoferetal., author = {Heitmann, Nadja and Glemnitz, Michael and Birkhofer, Klaus and M{\"u}ller, Marina E. H.}, title = {Unselective Transport of Phytopathogenic Fusarium Fungi from Litter and Soil by Ground-Dwelling Arthropods Links Semi-Natural and Agricultural Habitats}, series = {Microorganisms}, volume = {10}, journal = {Microorganisms}, number = {2}, issn = {2076-2607}, doi = {10.3390/microorganisms10020335}, abstract = {The dispersal of propagules, such as fungal spores or seeds by actively moving animals, connects and shapes communities. The dispersal of plant pathogens by arthropods might be a crucial mechanism in the spread of several crop diseases. Ground-dwelling arthropods are potential linkers between fungal communities in semi-natural and agricultural habitats by transporting propagules of Fusarium fungi. We compared the Fusarium communities on the body surface of ground-dwelling arthropods with litter in semi-natural and soil in agricultural habitats with a focus on the Fusarium community. We found three relatively distinct Fusarium communities with moderate overlap. We detected a higher richness of Fusarium species on the body surface of arthropods compared to litter and soil communities. The results suggest that the Fusarium community on the body surface of arthropods relates to the composition observed in litter and soil with limited filtering mechanisms between communities. Ground-dwelling arthropods are relevant agents for the distribution of Fusarium and therefore link fungal communities in adjacent habitats.}, language = {en} } @techreport{SchmidtDonathWelsetal., author = {Schmidt, Peer and Donath, Ines and Wels, Martin and Pinnau, Sebastian and Grau Turuelo, Constantino and Breitkopf, Cornelia and Hack, Klaus and Baben, Moritz to and Reis, Bruno and M{\"u}ller, Michael and Sergeev, Dmitry and Qi, Jia}, title = {PCM Screening - Evaluierung eutektischer Gemische f{\"u}r den Einsatz als PCM: thermodynamische Modellierung und experimentelle Methoden : Energie Speicher: PCM-Screening : Schlussbericht}, publisher = {TIB - Leibniz-Informationszentrum Technik und Naturwissenschaften}, address = {Hannover}, doi = {10.2314/KXP:177643451X}, pages = {163}, abstract = {Ein wichtiges Ziel der Bundesregierung ist der Ausbau des Anteils erneuerbarer Energien an der gesamten Stromerzeugung. Die Entwicklung optimierter W{\"a}rme- und K{\"a}ltespeicher stellt einen wichtigen Baustein bei der Erreichung dieser Zielstellung dar. Elektrisch betriebene W{\"a}rmepumpen und Kompressionsk{\"a}ltemaschinen sowie dezentrale Klein-BHKW bieten in Verbindung mit entsprechend dimensionierten, thermischen Speichern ein großes Potential zum Lastmanagement in Smart Grids und somit zur Netzintegration von Strom aus erneuerbaren Energien. Die im Projekt entwickelte Methodik zur Suche nach neuen Latentspeichermedien kann f{\"u}r ein breites Anwendungsfeld von Heiz- und K{\"u}hlanwendungen in Geb{\"a}uden bis hin zur Kraftwerkstechnik eingesetzt werden. Innerhalb der F{\"o}rdermaßnahme „Anwendungsorientierte Forschung und Entwicklung zur nichtnuklearen Energieforschung" im 6. Energieforschungsprogramm der Bundesregierung wurde durch die Projektarbeiten das Schwerpunktthema Energiespeicher (3.8) adressiert, wobei der Aspekt der Entwicklung neuer Materialien mit reduzierten Kosten f{\"u}r einen wirtschaftlichen Betrieb im Vordergrund stand. Speziell wurden dabei die Unterpunkte 3.8.4 Thermische Speicher zur Weiterentwicklung, Optimierung und Erprobung von PCM sowie 3.8.5 {\"U}bergeordnete Themen mit Modellen und Simulationswerkzeugen f{\"u}r die Auswahl und Bewertung neuer Speichermaterialien adressiert. Die Projektergebnisse besitzen aber auch Ber{\"u}hrungspunkte mit den Schwerpunkten 3.12 Energieeffizienz in Industrie, Gewerbe, Handel und Dienstleistungen sowie 3.4 Solarthermische Kraftwerke, da mit der entwickelten Screening-Methode f{\"u}r diese Anwendungsf{\"a}lle neue W{\"a}rmespeichermaterialien auf der Basis wasserfreier Salze mit h{\"o}heren Prozesstemperaturen gefunden werden k{\"o}nnen. Durch den Einsatz von Methoden zur Modellierung und Simulation von Prozessen erfolgt gleichermaßen die Umsetzung einer energie- und ressourcenschonenden Forschungst{\"a}tigkeit. Das im Projekt entwickelte Vorgehen hilft dabei, einen {\"a}ußerst sparsamen Einsatz von Chemikalien, eine niedrige Belastung der Umwelt durch verringerten Entsorgungsaufwand der verbrauchten Stoffe sowie einen deutlich geringeren Aufwand und Energieeinsatz f{\"u}r die Messtechnik zu erm{\"o}glichen. Damit wurde zugleich das Schwerpunktthema 3.8.5 Modelle und Simulationswerkzeuge f{\"u}r die Auswahl und Bewertung neuer Speichermaterialien angesprochen.}, language = {de} } @misc{MuellerBrandlCadotteetal., author = {M{\"u}ller, J{\"o}rg and Brandl, Roland and Cadotte, Marc W. and Heibl, Christoph and B{\"a}ssler, Claus and Weiß, Ingmar and Birkhofer, Klaus}, title = {A replicated study on the response of spider assemblages to regional and local processes}, series = {Ecological Monographs}, volume = {92}, journal = {Ecological Monographs}, number = {3}, issn = {1557-7015}, doi = {10.1002/ecm.1511}, pages = {1 -- 19}, abstract = {Understanding species richness variation among local communities is one of the central topics in ecology, but the complex interplay of regional processes, environmental filtering, and local processes hampers generalization on the importance of different processes. Here, we aim to unravel drivers of spider community assembly in temperate forests by analyzing two independent data sets covering gradients in elevation and forest succession. We test the following four hypotheses: (H1) spider assemblages within a region are limited by dispersal, (H2) local environment has a dominant influence on species composition and (H3) resources, and (H4) biotic interactions both affect species richness patterns. In a comprehensive approach, we studied species richness, abundance, taxonomic composition, and trait-phylogenetic dissimilarity of assemblages. The decrease in taxonomic similarity with increasing spatial distance was very weak, failing to support H1. Functional clustering of species in general and with canopy openness strongly supported H2. Moreover, this hypothesis was supported by a positive correlation between environmental and taxonomic similarity and by an increase in abundance with canopy openness. Resource determination of species richness (H3) could be confirmed only by the decrease of species richness with canopy cover. Finally, decreasing species richness with functional clustering indicating effects of biotic interactions (H4) could only be found in one analysis and only in one data set. In conclusion, our findings indicate that spider assemblages within a region are mainly determined by local environmental conditions, while resource availability, biotic interactions and dispersal play a minor role. Our approach shows that both the analysis of different aspects of species diversity and replication of community studies are necessary to identify the complex interplay of processes forming local assemblages.}, language = {en} } @misc{KoenigMuellerHoeschler, author = {K{\"o}nig, Paul and M{\"u}ller, Phillip and H{\"o}schler, Klaus}, title = {Assessment of (hybrid)-electric drive-train architectures for future aircraft applications}, series = {Journal of Physics: Conference Series}, volume = {2526}, journal = {Journal of Physics: Conference Series}, issn = {1742-6596}, doi = {10.1088/1742-6596/2526/1/012023}, abstract = {Future regional aircraft and propulsion systems will have to address both a growing market and stricter environmental constraints. Besides the increase of component efficiencies, the technological transformation from conventional to (hybrid)-electric propulsion systems represents a paradigm shift with great potential for the aviation industry. In this context, economic, market-relevant as well as technological boundary conditions for the electrical and mechanical components are developed in this paper for a reference regional aircraft and are based on current research results from different institutions. The propulsion performance analysis of a conventional turboprop is compared and evaluated with a serial-hybrid and a fully-electric configuration (both battery-electric), status today as well as status ~2035, as an example, whereby the presented process can also be applied to other hybrid configurations too. An energy-optimised propulsion and operating concept is derived with regard to minimum resulting system weight. The results of this analysis help to define necessary boundary conditions for future subsystem investigations and identify key research items, especially in the field of the battery.}, language = {en} } @misc{SchmeisserMuellerHenkel, author = {Schmeißer, Dieter and M{\"u}ller, Klaus and Henkel, Karsten}, title = {Photosensitive and Rectifying Properties of Ga2O3 Described by Polaronic Screened Electrons and Internal Potentials}, series = {Journal of Physical Chemistry C}, volume = {127}, journal = {Journal of Physical Chemistry C}, number = {47}, issn = {1932-7447}, doi = {10.1021/acs.jpcc.3c05785}, pages = {23077 -- 23089}, abstract = {The photosensitive and rectifying properties of Ga2O3 are described by (n-type) intrinsic (π-) electrons. These polaronic screened multiatomic carriers populate the intrinsic defect states within the ionic gap; their spectroscopic evidence is based on resonant photoemission spectroscopy data that also provide the ionicity factor of Ga2O3 and the size of the ionic gap. The π-electron density depends on the internal potential and its photo- and field-induced dipole contributions, and it describes the observed combined ohmic-exponential carrier densities and current-voltage dependences. The π-electron dynamics is caused by pairing and dissociation dipoles in the bulk of Ga2O3. The material properties of the electrode contribute via external chemical potentials and define the criteria for ohmic and rectifying contacts. This quantitative and predictive concept not only convinces by perfect agreement with published experimental data but also points toward the achievable performance limits of UV absorbers and rectifying devices.}, language = {en} } @misc{AubeleGrillEggertetal., author = {Aubele, Maria and Grill, Eva and Eggert, Thomas and Schneider, Erich and Strobl, Ralf and Jahn, Klaus and M{\"u}ller, Martin and Holle, Rolf and Linkohr, Birgit and Heier, Margit and Ladwig, Karl-Heinz and Lehnen, Nadine}, title = {Symptoms in unilatral vestibular hypofunction are associated with number of catch-up saccades and retinal errors: results from the population-based KORA FF4study}, series = {Frontiers in Neurology}, volume = {2023}, journal = {Frontiers in Neurology}, number = {14}, issn = {1664-2295}, pages = {8}, abstract = {Objective: The presence and intensity of symptoms vary in patients with unilateral vestibular hypofunction. We aimed to determine which saccadic and vestibulo-ocular reflex parameters best predict the presence of symptoms in unilateral vestibular hypofunction in order to better understand vestibular compensation and its implications for rehabilitation therapy. Methods: Video head impulse test data were analyzed from a subpopulation of 23 symptomatic and 10 currently symptom-free participants with unilateral vestibular hypofunction, embedded in the KORA (Cooperative Health Research in the Region of Augsburg) FF4 study, the second follow-up of the KORA S4 population-based health survey (2,279 participants). Results: A higher number of catch-up saccades, a higher percentage of covert saccades, and a larger retinal error at 200 ms after the onset of the head impulse were associated with relevant symptoms in participants with unilateral vestibular hypofunction (p = 0.028, p = 0.046, and p = 0.038, respectively). After stepwise selection, the number of catch-up saccades and retinal error at 200 ms remained in the final logistic regression model, which was significantly better than a null model (p = 0.014). Age, gender, saccade amplitude, saccade latency, and VOR gain were not predictive of the presence of symptoms. Conclusion: The accuracy of saccadic compensation seems to be crucial for the presence of symptoms in unilateral vestibular hypofunction, highlighting the role of specific gaze stabilization exercises in rehabilitation. Early saccades, mainly triggered by the vestibular system, do not seem to compensate accurately enough, resulting in a relevant retinal error and the need for more as well as more accurate catch-up saccades, probably triggered by the visual system.}, language = {en} }