@misc{PerovicZeiningerOschatz2020, author = {Perovic, Milena and Zeininger, Lukas and Oschatz, Martin}, title = {Immobilization of gold-on-carbon catalysts onto perfluorocarbon emulsion droplets to promote oxygen delivery in aqueous phase (D)-glucose oxidation}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1}, issn = {1867-3880}, doi = {10.25932/publishup-56947}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-569471}, pages = {8}, year = {2020}, abstract = {The catalytic activity of metal nanoparticles (NPs) supported on porous supports can be controlled by various factors, such as NPs size, shape, or dispersivity, as well as their interaction with the support or the properties of the support material itself. However, these intrinsic properties are not solely responsible for the catalytic behavior of the overall reaction system, as the local environment and surface coverage of the catalyst with reactants, products, intermediates and other invloved species often play a crucial role in catalytic processes as well. Their contribution can be particularly critical in liquid-phase reactions with gaseous reactants that often suffer from low solubiltiy. One example is (D)-glucose oxidation with molecular oxygen over gold nanoparticles supported on porous carbons. The possibility to promote oxygen delivery in such aqueous phase oxidation reactions via the immobilization of heterogenous catalysts onto the interface of perfluorocarbon emulsion droplets is reported here. Gold-on-carbon catalyst particles can stabilize perfluorocarbon droplets in the aqueous phase and the local concentration of the oxidant in the surroundings of the gold nanoparticles accelerates the rate-limiting step of the reaction. Consequently, the reaction rate of a system with the optimal volume fraction of fluorocarbon is higher than a reference emulsion system without fluorocarbon, and the effect is observed even without additional oxygen supply.}, language = {en} } @article{MarschallSkorovZakharovetal.2020, author = {Marschall, Raphael and Skorov, Yuri and Zakharov, Vladimir and Rezac, Ladislav and Gerig, Selina-Barbara and Christou, Chariton and Dadzie, S. Kokou and Migliorini, Alessandra and Rinaldi, Giovanna and Agarwal, Jessica and Vincent, Jean-Baptiste and Kappel, David}, title = {Cometary comae-surface links the physics of gas and dust from the surface to a spacecraft}, series = {Space science reviews}, volume = {216}, journal = {Space science reviews}, number = {8}, publisher = {Springer}, address = {Dordrecht}, issn = {0038-6308}, doi = {10.1007/s11214-020-00744-0}, pages = {53}, year = {2020}, abstract = {A comet is a highly dynamic object, undergoing a permanent state of change. These changes have to be carefully classified and considered according to their intrinsic temporal and spatial scales. The Rosetta mission has, through its contiguous in-situ and remote sensing coverage of comet 67P/Churyumov-Gerasimenko (hereafter 67P) over the time span of August 2014 to September 2016, monitored the emergence, culmination, and winding down of the gas and dust comae. This provided an unprecedented data set and has spurred a large effort to connect in-situ and remote sensing measurements to the surface. In this review, we address our current understanding of cometary activity and the challenges involved when linking comae data to the surface. We give the current state of research by describing what we know about the physical processes involved from the surface to a few tens of kilometres above it with respect to the gas and dust emission from cometary nuclei. Further, we describe how complex multidimensional cometary gas and dust models have developed from the Halley encounter of 1986 to today. This includes the study of inhomogeneous outgassing and determination of the gas and dust production rates. Additionally, the different approaches used and results obtained to link coma data to the surface will be discussed. We discuss forward and inversion models and we describe the limitations of the respective approaches. The current literature suggests that there does not seem to be a single uniform process behind cometary activity. Rather, activity seems to be the consequence of a variety of erosion processes, including the sublimation of both water ice and more volatile material, but possibly also more exotic processes such as fracture and cliff erosion under thermal and mechanical stress, sub-surface heat storage, and a complex interplay of these processes. Seasons and the nucleus shape are key factors for the distribution and temporal evolution of activity and imply that the heliocentric evolution of activity can be highly individual for every comet, and generalisations can be misleading.}, language = {en} } @article{PerovicZeiningerOschatz2020, author = {Perovic, Milena and Zeininger, Lukas and Oschatz, Martin}, title = {Immobilization of gold-on-carbon catalysts onto perfluorocarbon emulsion droplets to promote oxygen delivery in aqueous phase (D)-glucose oxidation}, series = {ChemCatChem}, volume = {13}, journal = {ChemCatChem}, number = {1}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1867-3880}, doi = {10.1002/cctc.202001590}, pages = {196 -- 201}, year = {2020}, abstract = {The catalytic activity of metal nanoparticles (NPs) supported on porous supports can be controlled by various factors, such as NPs size, shape, or dispersivity, as well as their interaction with the support or the properties of the support material itself. However, these intrinsic properties are not solely responsible for the catalytic behavior of the overall reaction system, as the local environment and surface coverage of the catalyst with reactants, products, intermediates and other invloved species often play a crucial role in catalytic processes as well. Their contribution can be particularly critical in liquid-phase reactions with gaseous reactants that often suffer from low solubiltiy. One example is (D)-glucose oxidation with molecular oxygen over gold nanoparticles supported on porous carbons. The possibility to promote oxygen delivery in such aqueous phase oxidation reactions via the immobilization of heterogenous catalysts onto the interface of perfluorocarbon emulsion droplets is reported here. Gold-on-carbon catalyst particles can stabilize perfluorocarbon droplets in the aqueous phase and the local concentration of the oxidant in the surroundings of the gold nanoparticles accelerates the rate-limiting step of the reaction. Consequently, the reaction rate of a system with the optimal volume fraction of fluorocarbon is higher than a reference emulsion system without fluorocarbon, and the effect is observed even without additional oxygen supply.}, language = {en} } @misc{BouchouleSchemmerHenkel2018, author = {Bouchoule, Isabelle and Schemmer, Max and Henkel, Carsten}, title = {Cooling phonon modes of a Bose condensate with uniform few body losses}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1029}, issn = {1866-8372}, doi = {10.25932/publishup-46881}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-468811}, pages = {20}, year = {2018}, abstract = {We present a general analysis of the cooling produced by losses on condensates or quasi-condensates. We study how the occupations of the collective phonon modes evolve in time, assuming that the loss process is slow enough so that each mode adiabatically follows the decrease of the mean density. The theory is valid for any loss process whose rate is proportional to the jth power of the density, but otherwise spatially uniform. We cover both homogeneous gases and systems confined in a smooth potential. For a low-dimensional gas, we can take into account the modified equation of state due to the broadening of the cloud width along the tightly confined directions, which occurs for large interactions. We find that at large times, the temperature decreases proportionally to the energy scale mc2, where m is the mass of the particles and c the sound velocity. We compute the asymptotic ratio of these two quantities for different limiting cases: a homogeneous gas in any dimension and a one-dimensional gas in a harmonic trap.}, language = {en} } @book{Boehme2013, author = {B{\"o}hme, Dimo}, title = {EU-Russia energy relations: What chance for solutions? : A focus on the natural gas sector}, isbn = {978-3-86956-278-0}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63022}, publisher = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Public debate about energy relations between the EU and Russia is distorted. These distortions present considerable obstacles to the development of true partnership. At the core of the conflict is a struggle for resource rents between energy producing, energy consuming and transit countries. Supposed secondary aspects, however, are also of great importance. They comprise of geopolitics, market access, economic development and state sovereignty. The European Union, having engaged in energy market liberalisation, faces a widening gap between declining domestic resources and continuously growing energy demand. Diverse interests inside the EU prevent the definition of a coherent and respected energy policy. Russia, for its part, is no longer willing to subsidise its neighbouring economies by cheap energy exports. The Russian government engages in assertive policies pursuing Russian interests. In so far, it opts for a different globalisation approach, refusing the role of mere energy exporter. In view of the intensifying struggle for global resources, Russia, with its large energy potential, appears to be a very favourable option for European energy supplies, if not the best one. However, several outcomes of the strategic game between the two partners can be imagined. Engaging in non-cooperative strategies will in the end leave all stakeholders worse-off. The European Union should therefore concentrate on securing its partnership with Russia instead of damaging it. Stable cooperation would need the acceptance that the partner may pursue his own goals, which might be different from one's own interests. The question is, how can a sustainable compromise be found? This thesis finds that a mix of continued dialogue, a tit for tat approach bolstered by an international institutional framework and increased integration efforts appears as a preferable solution.}, language = {en} } @phdthesis{Boehme2011, author = {B{\"o}hme, Dimo}, title = {EU-Russia energy relations: What chance for solutions? : A focus on the natural gas sector}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-120-2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-50210}, school = {Universit{\"a}t Potsdam}, pages = {xix, 322}, year = {2011}, abstract = {Public debate about energy relations between the EU and Russia is distorted. These distortions present considerable obstacles to the development of true partnership. At the core of the conflict is a struggle for resource rents between energy producing, energy consuming and transit countries. Supposed secondary aspects, however, are also of great importance. They comprise of geopolitics, market access, economic development and state sovereignty. The European Union, having engaged in energy market liberalisation, faces a widening gap between declining domestic resources and continuously growing energy demand. Diverse interests inside the EU prevent the definition of a coherent and respected energy policy. Russia, for its part, is no longer willing to subsidise its neighbouring economies by cheap energy exports. The Russian government engages in assertive policies pursuing Russian interests. In so far, it opts for a different globalisation approach, refusing the role of mere energy exporter. In view of the intensifying struggle for global resources, Russia, with its large energy potential, appears to be a very favourable option for European energy supplies, if not the best one. However, several outcomes of the strategic game between the two partners can be imagined. Engaging in non-cooperative strategies will in the end leave all stakeholders worse-off. The European Union should therefore concentrate on securing its partnership with Russia instead of damaging it. Stable cooperation would need the acceptance that the partner may pursue his own goals, which might be different from one's own interests. The question is, how can a sustainable compromise be found? This thesis finds that a mix of continued dialogue, a tit for tat approach bolstered by an international institutional framework and increased integration efforts appears as a preferable solution.}, language = {en} }