@misc{KashkarovObrosovSutyginaetal.2018, author = {Kashkarov, Egor B. and Obrosov, Aleksei and Sutygina, Alina N. and Uludintceva, Elena and Mitrofanov, Andrei and Weiß, Sabine}, title = {Hydrogen permeation, and mechanical and tribological behavior, of CrNx coatings deposited at various bias voltages on IN718 by direct current reactive sputtering}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, number = {1017}, issn = {1866-8372}, doi = {10.25932/publishup-45984}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459846}, pages = {14}, year = {2018}, abstract = {In the current work, the microstructure, hydrogen permeability, and properties of chromium nitride (CrNx) thin films deposited on the Inconel 718 superalloy using direct current reactive sputtering are investigated. The influence of the substrate bias voltage on the crystal structure, mechanical, and tribological properties before and after hydrogen exposure was studied. It was found that increasing the substrate bias voltage leads to densification of the coating. X-ray diffraction (XRD) results reveal a change from mixed fcc-CrN + hcp-Cr2N to the approximately stoichiometric hcp-Cr2N phase with increasing substrate bias confirmed by wavelength-dispersive X-ray spectroscopy (WDS). The texture coefficients of (113), (110), and (111) planes vary significantly with increasing substrate bias voltage. The hydrogen permeability was measured by gas-phase hydrogenation. The CrN coating deposited at 60 V with mixed c-CrN and (113) textured hcp-Cr2N phases exhibits the lowest hydrogen absorption at 873 K. It is suggested that the crystal orientation is only one parameter influencing the permeation resistance of the CrNx coating together with the film structure, the presence of mixing phases, and the packing density of the structure. After hydrogenation, the hardness increased for all coatings, which could be related to the formation of a Cr2O3 oxide film on the surface, as well as the defect formation after hydrogen loading. Tribological tests reveal that hydrogenation leads to a decrease of the friction coefficient by up to 40\%. The lowest value of 0.25 +/- 0.02 was reached for the CrNx coating deposited at 60 V after hydrogenation.}, language = {en} } @article{ZuehlkeMeilingRoderetal.2021, author = {Z{\"u}hlke, Martin and Meiling, Till Thomas and Roder, Phillip and Riebe, Daniel and Beitz, Toralf and Bald, Ilko and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Janßen, Traute and Erhard, Marcel and Repp, Alexander}, title = {Photodynamic inactivation of E. coli bacteria via carbon nanodots}, series = {ACS omega / American Chemical Society}, volume = {6}, journal = {ACS omega / American Chemical Society}, number = {37}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {2470-1343}, doi = {10.1021/acsomega.1c01700}, pages = {23742 -- 23749}, year = {2021}, abstract = {The increasing development of antibiotic resistance in bacteria has been a major problem for years, both in human and veterinary medicine. Prophylactic measures, such as the use of vaccines, are of great importance in reducing the use of antibiotics in livestock. These vaccines are mainly produced based on formaldehyde inactivation. However, the latter damages the recognition elements of the bacterial proteins and thus could reduce the immune response in the animal. An alternative inactivation method developed in this work is based on gentle photodynamic inactivation using carbon nanodots (CNDs) at excitation wavelengths λex > 290 nm. The photodynamic inactivation was characterized on the nonvirulent laboratory strain Escherichia coli K12 using synthesized CNDs. For a gentle inactivation, the CNDs must be absorbed into the cytoplasm of the E. coli cell. Thus, the inactivation through photoinduced formation of reactive oxygen species only takes place inside the bacterium, which means that the outer membrane is neither damaged nor altered. The loading of the CNDs into E. coli was examined using fluorescence microscopy. Complete loading of the bacterial cells could be achieved in less than 10 min. These studies revealed a reversible uptake process allowing the recovery and reuse of the CNDs after irradiation and before the administration of the vaccine. The success of photodynamic inactivation was verified by viability assays on agar. In a homemade flow photoreactor, the fastest successful irradiation of the bacteria could be carried out in 34 s. Therefore, the photodynamic inactivation based on CNDs is very effective. The membrane integrity of the bacteria after irradiation was verified by slide agglutination and atomic force microscopy. The method developed for the laboratory strain E. coli K12 could then be successfully applied to the important avian pathogens Bordetella avium and Ornithobacterium rhinotracheale to aid the development of novel vaccines.}, language = {en} } @article{RobinsonNiebuhrLeveretal.2021, author = {Robinson, Matthew Scott and Niebuhr, Mario and Lever, Fabiano and Mayer, Dennis and Metje, Jan and G{\"u}hr, Markus}, title = {Ultrafast photo-ion probing of the ring-opening process in trans-stilbene oxide}, series = {Chemistry - a European journal}, volume = {27}, journal = {Chemistry - a European journal}, number = {44}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-3765}, doi = {10.1002/chem.202101343}, pages = {11418 -- 11427}, year = {2021}, abstract = {The ultrafast photo-induced ring opening of the oxirane derivative trans-stilbene oxide has been studied through the use of ultrafast UV/UV pump-probe spectroscopy by using photo-ion detection. Single- and multiphoton probe paths and final states were identified through comparisons between UV power studies and synchrotron-based vacuum ultraviolet (VUV) single-photon ionization studies. Three major time-dependent features of the parent ion (sub-450 fs decay, (1.5 +/- 0.2) ps, and >100 ps) were observed. These decays are discussed in conjunction with the primary ring-opening mechanism of stilbene oxide, which occurs through C-C dissociation in the oxirane ring. The appearance of fragments relating to the masses of dehydrogenated diphenylmethane (167 amu) and dehydrogenated methylbenzene (90 amu) were also investigated. The appearance of the 167 amu fragment could suggest an alternative ultrafast ring-opening pathway via the dissociation of one of the C-O bonds within the oxirane ring.}, language = {en} } @article{SchladebachBarsan2023, author = {Schladebach, Marcus and B{\^a}rsan, Catinca}, title = {Der Mondbergbau als v{\"o}lkerrechtliche Herausforderung}, series = {Zeitschrift f{\"u}r Bergrecht}, volume = {164}, journal = {Zeitschrift f{\"u}r Bergrecht}, number = {2}, publisher = {Carl Heymanns Verlag}, address = {K{\"o}ln}, issn = {0340-3939}, pages = {97 -- 107}, year = {2023}, language = {de} } @article{HackethalKoppSarvanetal.2021, author = {Hackethal, Christin and Kopp, Johannes Florian and Sarvan, Irmela and Schwerdtle, Tanja and Lindtner, Oliver}, title = {Total arsenic and water-soluble arsenic species in foods of the first German total diet study (BfR MEAL Study)}, series = {Food chemistry}, volume = {346}, journal = {Food chemistry}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, issn = {0308-8146}, doi = {10.1016/j.foodchem.2020.128913}, pages = {10}, year = {2021}, abstract = {Arsenic can occur in foods as inorganic and organic forms. Inorganic arsenic is more toxic than most watersoluble organic arsenic compounds such as arsenobetaine, which is presumed to be harmless for humans. Within the first German total diet study, total arsenic, inorganic arsenic, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid were analyzed in various foods. Highest levels of total arsenic were found in fish, fish products and seafood (mean: 1.43 mg kg(-1); n = 39; min-max: 0.01-6.15 mg kg(-1)), with arsenobetaine confirmed as the predominant arsenic species (1.233 mg kg 1; n = 39; min-max: 0.01-6.23 mg kg (1)). In contrast, inorganic arsenic was determined as prevalent arsenic species in terrestrial foods (0.02 mg kg (1); n = 38; min-max: 0-0.11 mg kg (1)). However, the toxicity of arsenic species varies and measurements are necessary to gain information about the composition and changes of arsenic species in foods due to household processing of foods.}, language = {en} } @article{KeckeisZellerJungetal.2021, author = {Keckeis, Philipp and Zeller, Enriko and Jung, Carina and Besirske, Patricia and Kirner, Felizitas and Ruiz-Agudo, Cristina and Schlaad, Helmut and C{\"o}lfen, Helmut}, title = {Modular toolkit of multifunctional block copoly(2-oxazoline)s for the synthesis of nanoparticles}, series = {Chemistry - a European journal}, volume = {27}, journal = {Chemistry - a European journal}, number = {32}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.202101327}, pages = {8283 -- 8287}, year = {2021}, abstract = {Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.}, language = {en} } @misc{NiedlBeta2015, author = {Niedl, Robert Raimund and Beta, Carsten}, title = {Hydrogel-driven paper-based microfluidics}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-81083}, pages = {2452 -- 2459}, year = {2015}, abstract = {Paper-based microfluidics provide an inexpensive, easy to use technology for point-of-care diagnostics in developing countries. Here, we combine paper-based microfluidic devices with responsive hydrogels to add an entire new class of functions to these versatile low-cost fluidic systems. The hydrogels serve as fluid reservoirs. In response to an external stimulus, e.g. an increase in temperature, the hydrogels collapse and release fluid into the structured paper substrate. In this way, chemicals that are either stored on the paper substrate or inside the hydrogel pads can be dissolved, premixed, and brought to reaction to fulfill specific analytic tasks. We demonstrate that multi-step sequences of chemical reactions can be implemented in a paper-based system and operated without the need for external precision pumps. We exemplify this technology by integrating an antibody-based E. coli test on a small and easy to use paper device.}, language = {en} } @article{LaquaiSchauppGriescheetal.2022, author = {Laquai, Ren{\´e} and Schaupp, Thomas and Griesche, Axel and M{\"u}ller, Bernd R. and Kupsch, Andreas and Hannemann, Andreas and Kannengiesser, Thomas and Bruno, Giovanni}, title = {Quantitative analysis of hydrogen-assisted microcracking in duplex stainless steel through X-ray refraction 3D imaging}, series = {Advanced engineering materials}, volume = {24}, journal = {Advanced engineering materials}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1527-2648}, doi = {10.1002/adem.202101287}, pages = {10}, year = {2022}, abstract = {While the problem of the identification of mechanisms of hydrogen-assisted damage has and is being thoroughly studied, the quantitative analysis of such damage still lacks suitable tools. In fact, while, for instance, electron microscopy yields excellent characterization, the quantitative analysis of damage requires at the same time large field-of-views and high spatial resolution. Synchrotron X-ray refraction techniques do possess both features. Herein, it is shown how synchrotron X-ray refraction computed tomography (SXRCT) can quantify damage induced by hydrogen embrittlement in a lean duplex steel, yielding results that overperform even those achievable by synchrotron X-ray absorption computed tomography. As already reported in the literature, but this time using a nondestructive technique, it is shown that the hydrogen charge does not penetrate to the center of tensile specimens. By the comparison between virgin and hydrogen-charged specimens, it is deduced that cracks in the specimen bulk are due to the rolling process rather than hydrogen-assisted. It is shown that (micro)cracks propagate from the surface of tensile specimens to the interior with increasing applied strain, and it is deduced that a significant crack propagation can only be observed short before rupture.}, language = {en} } @article{BalischewskiBehrensZehbeetal.2020, author = {Balischewski, Christian and Behrens, Karsten and Zehbe, Kerstin and G{\"u}nter, Christina and Mies, Stefan and Sperlich, Eric and Kelling, Alexandra and Taubert, Andreas}, title = {Ionic liquids with more than one metal}, series = {Chemistry - a European journal}, volume = {26}, journal = {Chemistry - a European journal}, number = {72}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.202003097}, pages = {17504 -- 17513}, year = {2020}, abstract = {Thirteen N-butylpyridinium salts, including three monometallic [C4Py](2)[MCl4], nine bimetallic [C4Py](2)[(M1-xMxCl4)-M-a-Cl-b] and one trimetallic compound [C4Py](2)[(M1-y-zMyMz (c) Cl4)-M-a-M-b] (M=Co, Cu, Mn; x=0.25, 0.50 or 0.75 and y=z=0.33), were synthesized and their structure and thermal and electrochemical properties were studied. All compounds are ionic liquids (ILs) with melting points between 69 and 93 degrees C. X-ray diffraction proves that all ILs are isostructural. The conductivity at room temperature is between 10(-4) and 10(-8) S cm(-1). Some Cu-based ILs reach conductivities of 10(-2) S cm(-1), which is, however, probably due to IL dec. This correlates with the optical bandgap measurements indicating the formation of large bandgap semiconductors. At elevated temperatures approaching the melting points, the conductivities reach up to 1.47x10(-1) S cm(-1) at 70 degrees C. The electrochemical stability windows of the ILs are between 2.5 and 3.0 V.}, language = {en} } @article{SprengelMohrAltenburgetal.2021, author = {Sprengel, Maximilian and Mohr, Gunther and Altenburg, Simon J. and Evans, Alexander and Serrano-Munoz, Itziar and Kromm, Arne and Pirling, Thilo and Bruno, Giovanni and Kannengießer, Thomas}, title = {Triaxial residual stress in Laser Powder Bed Fused 316L}, series = {Advanced engineering materials}, volume = {24}, journal = {Advanced engineering materials}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1438-1656}, doi = {10.1002/adem.202101330}, pages = {13}, year = {2021}, abstract = {The control of residual stress (RS) remains a challenge in the manufacturing of metallic parts using the laser powder bed fusion process (LPBF). This layer-by-layer manufacturing approach gives rise to complex triaxial RS distributions, which require extensive characterization effort for a broader acceptance of LPBF in industry. This study focuses on the distribution of bulk triaxial RS and surface RS in LPBF austenitic steel 316L. The RS are determined by X-ray and neutron diffraction to characterize the RS distribution. Variations in the LPBF parameters interlayer time (ILT) and scanning velocity and their influence on the temperature distribution and resulting RS is investigated using thermographic data from in situ process monitoring. The RS in the LPBF 316L is tensile at the surface and compressive in the bulk. The RS is directly related to the thermal history of the part as shown by the in situ thermography data. Shorter ILT leads to higher temperatures of the part during the manufacturing, which decrease the RS and RS formation mechanisms. Interestingly, the surface RS does not agree with this observation. This study highlights the benefit of using multiple RS determination methods and in situ thermography monitoring to characterize the RS in LPBF processed parts.}, language = {en} } @article{SorgenfreiGiangrisostomiJayetal.2021, author = {Sorgenfrei, Nomi and Giangrisostomi, Erika and Jay, Raphael Martin and K{\"u}hn, Danilo and Neppl, Stefan and Ovsyannikov, Ruslan and Sezen, Hikmet and Svensson, Svante and F{\"o}hlisch, Alexander}, title = {Photodriven transient picosecond top-layer semiconductor to metal phase-transition in p-doped molybdenum disulfide}, series = {Advanced materials}, volume = {33}, journal = {Advanced materials}, number = {14}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0935-9648}, doi = {10.1002/adma.202006957}, pages = {8}, year = {2021}, abstract = {Visible light is shown to create a transient metallic S-Mo-S surface layer on bulk semiconducting p-doped indirect-bandgap 2H-MoS2. Optically created electron-hole pairs separate in the surface band bending region of the p-doped semiconducting crystal causing a transient accumulation of electrons in the surface region. This triggers a reversible 2H-semiconductor to 1T-metal phase-transition of the surface layer. Electron-phonon coupling of the indirect-bandgap p-doped 2H-MoS2 enables this efficient pathway even at a low density of excited electrons with a distinct optical excitation threshold and saturation behavior. This mechanism needs to be taken into consideration when describing the surface properties of illuminated p-doped 2H-MoS2. In particular, light-induced increased charge mobility and surface activation can cause and enhance the photocatalytic and photoassisted electrochemical hydrogen evolution reaction of water on 2H-MoS2. Generally, it opens up for a way to control not only the surface of p-doped 2H-MoS2 but also related dichalcogenides and layered systems. The findings are based on the sensitivity of time-resolved electron spectroscopy for chemical analysis with photon-energy-tuneable synchrotron radiation.}, language = {en} } @misc{EckertNorellMiedemaetal.2017, author = {Eckert, Sebastian and Norell, Jesper and Miedema, Piter S. and Beye, Martin and Fondell, Mattis and Quevedo, Wilson and Kennedy, Brian and Hantschmann, Markus and Pietzsch, Annette and van Kuiken, Benjamin E. and Ross, Matthew and Minitti, Michael P. and Moeller, Stefan P. and Schlotter, William F. and Khalil, Munira and Odelius, Michael and F{\"o}hlisch, Alexander}, title = {Untersuchung unabh{\"a}ngiger N-H- und N-C-Bindungsverformungen auf ultrakurzen Zeitskalen mit resonanter inelastischer R{\"o}ntgenstreuung}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1121}, issn = {1866-8372}, doi = {10.25932/publishup-43668}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436688}, pages = {7}, year = {2017}, abstract = {Die Femtosekundendynamik nach resonanten Photoanregungen mit optischen und R{\"o}ntgenpulsen erm{\"o}glicht eine selektive Verformung von chemischen N-H- und N-C-Bindungen in 2-Thiopyridon in w{\"a}ssriger L{\"o}sung. Die Untersuchung der orbitalspezifischen elektronischen Struktur und ihrer Dynamik auf ultrakurzen Zeitskalen mit resonanter inelastischer R{\"o}ntgenstreuung an der N1s-Resonanz am Synchrotron und dem Freie-Elektronen-Laser LCLS in Kombination mit quantenchemischen Multikonfigurationsberechnungen erbringen den direkten Nachweis dieser kontrollierten photoinduzierten Molek{\"u}lverformungen und ihrer ultrakurzen Zeitskala.}, language = {de} } @misc{EckertNorellMiedemaetal.2017, author = {Eckert, Sebastian and Norell, Jesper and Miedema, Piter S. and Beye, Martin and Fondell, Mattis and Quevedo, Wilson and Kennedy, Brian and Hantschmann, Markus and Pietzsch, Annette and van Kuiken, Benjamin E. and Ross, Matthew and Minitti, Michael P. and Moeller, Stefan P. and Schlotter, William F. and Khalil, Munira and Odelius, Michael and F{\"o}hlisch, Alexander}, title = {Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {1115}, issn = {1866-8372}, doi = {10.25932/publishup-43687}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436873}, pages = {7}, year = {2017}, abstract = {The femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort time-scale.}, language = {en} } @article{GilmanovaWangGosensetal.2021, author = {Gilmanova, Alina and Wang, Zhifeng and Gosens, Jorrit and Lilliestam, Johan}, title = {Building an internationally competitive concentrating solar power industry in China}, series = {Energy sources : B, economics, planning and policy}, volume = {16}, journal = {Energy sources : B, economics, planning and policy}, number = {6}, publisher = {Taylor \& Francis}, address = {London}, issn = {1556-7249}, doi = {10.1080/15567249.2021.1931563}, pages = {515 -- 541}, year = {2021}, abstract = {This article draws lessons from experiences of developing the photovoltaic (PV) and onshore wind power sectors in China for the development of Chinese Concentrated Solar Power (CSP) into an internationally competitive industry. We analyze the sectoral development with a framework that expands on the concept of lead markets, identifying factors that determine whether domestic industrial development paths may or may not generate export success. We find that the Chinese CSP sector has good potential for becoming internationally competitive because of a strong Chinese knowledge base, a clear eye for product quality, standard-setting, and a focus on the high-efficiency and large-storage technological routes most likely to see growing demand in future international markets. Chinese solar towers are already cheaper than international competitors and so far, appear reliable. However, continued and stable deployment support for CSP, designed to reward dispatchable solar power generation, enabling continued domestic learning-by-doing and -interacting is likely required to realize this export potential. To date, Chinese CSP policy has done many things right and, if the domestic market is maintained through renewed support, has put the Chinese industry well on the path to international competitiveness.}, language = {en} } @article{SilvaOliveiraCostaTchewonpietal.2021, author = {Silva, Bibiana and Oliveira Costa, Ana Carolina and Tchewonpi, Sorel Sagu and B{\"o}nick, Josephine and Huschek, Gerd and Gonzaga, Luciano Valdemiro and Fett, Roseane and Baldermann, Susanne and Rawel, Harshadrai Manilal}, title = {Comparative quantification and differentiation of bracatinga (Mimosa scabrella Bentham) honeydew honey proteins using targeted peptide markers identified by high-resolution mass spectrometry}, series = {Food research international}, volume = {141}, journal = {Food research international}, publisher = {Elsevier}, address = {New York, NY [u.a.]}, issn = {0963-9969}, doi = {10.1016/j.foodres.2020.109991}, pages = {10}, year = {2021}, abstract = {Honey traceability is an important topic, especially for honeydew honeys, due to the increased incidence of adulteration. This study aimed to establish specific markers to quantify proteins in honey. A proteomics strategy to identify marker peptides from bracatinga honeydew honey was therefore developed. The proteomics approach was based on initial untargeted identification of honey proteins and peptides by LC-ESI-Triple-TOF-MS/MS, which identified the major royal jelly proteins (MRJP) presence. Afterwards, the peptides were selected by the in silico digestion. The marker peptides were quantified by the developed targeted LC-QqQ-MS/MS method, which provided good linearity and specificity, besides recoveries between 92 and 100\% to quantify peptides from bracatinga honeydew honey. The uniqueness and high response in mass spectrometry were backed by further complementary protein analysis (SDS-PAGE). The selected marker peptides EALPHVPIFDR (MRJP 1), ILGANVK (MRJP 2), TFVTIER (MRJP 3), QNIDVVAR (MRJP 4), FINNDYNFNEVNFR (MRJP 5) and LLQPYPDWSWTK (MRJP 7), quantified by LC-QqQ-MS/MS, highlighted that the content of QNIDVVAR from MRJP 4 could be used to differentiate bracatinga honeydew honey from floral honeys (p < 0.05) as a potential marker for its authentication. Finally, principal components analysis highlighted the QNIDVVAR content as a good descriptor of the analyzed bracatinga honeydew honey samples.}, language = {en} } @article{WegerCoenenLeitaoLawrence2021, author = {Weger Coenen, Lindsey and Leit{\~a}o, Joana and Lawrence, Mark}, title = {Expected impacts on greenhouse gas and air pollutant emissions due to a possible transition towards a hydrogen economy in German road transport}, series = {International journal of hydrogen energy : official journal of the International Association for Hydrogen Energy}, volume = {46}, journal = {International journal of hydrogen energy : official journal of the International Association for Hydrogen Energy}, number = {7}, publisher = {Elsevier}, address = {Oxford}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2020.11.014}, pages = {5875 -- 5890}, year = {2021}, abstract = {Transitioning German road transport partially to hydrogen energy is among the possibilities being discussed to help meet national climate targets. This study investigates impacts of a hypothetical, complete transition from conventionally-fueled to hydrogen-powered German transport through representative scenarios. Our results show that German emissions change between -179 and +95 MtCO(2)eq annually, depending on the scenario, with renewable-powered electrolysis leading to the greatest emissions reduction, while electrolysis using the fossilintense current electricity mix leads to the greatest increase. German energy emissions of regulated pollutants decrease significantly, indicating the potential for simultaneous air quality improvements. Vehicular hydrogen demand is 1000 PJ annually, requiring 446-525 TWh for electrolysis, hydrogen transport and storage, which could be supplied by future German renewable generation, supporting the potential for CO2-free hydrogen traffic and increased energy security. Thus hydrogen-powered transport could contribute significantly to climate and air quality goals, warranting further research and political discussion about this possibility.}, language = {en} } @article{GeigerReitenbachHenscheletal.2021, author = {Geiger, Christina and Reitenbach, Julija and Henschel, Cristiane and Kreuzer, Lucas and Widmann, Tobias and Wang, Peixi and Mangiapia, Gaetano and Moulin, Jean-Fran{\c{c}}ois and Papadakis, Christine M. and Laschewsky, Andr{\´e} and M{\"u}ller-Buschbaum, Peter}, title = {Ternary nanoswitches realized with multiresponsive PMMA-b-PNIPMAM films in mixed water/acetone vapor atmospheres}, series = {Advanced engineering materials}, volume = {23}, journal = {Advanced engineering materials}, number = {11}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1438-1656}, doi = {10.1002/adem.202100191}, pages = {12}, year = {2021}, abstract = {To systematically add functionality to nanoscale polymer switches, an understanding of their responsive behavior is crucial. Herein, solvent vapor stimuli are applied to thin films of a diblock copolymer consisting of a short poly(methyl methacrylate) (PMMA) block and a long poly(N-isopropylmethacrylamide) (PNIPMAM) block for realizing ternary nanoswitches. Three significantly distinct film states are successfully implemented by the combination of amphiphilicity and co-nonsolvency effect. The exposure of the thin films to nitrogen, pure water vapor, and mixed water/acetone (90 vol\%/10 vol\%) vapor switches the films from a dried to a hydrated (solvated and swollen) and a water/acetone-exchanged (solvated and contracted) equilibrium state. These three states have distinctly different film thicknesses and solvent contents, which act as switch positions "off," "on," and "standby." For understanding the switching process, time-of-flight neutron reflectometry (ToF-NR) and spectral reflectance (SR) studies of the swelling and dehydration process are complemented by information on the local solvation of functional groups probed with Fourier-transform infrared (FTIR) spectroscopy. An accelerated responsive behavior beyond a minimum hydration/solvation level is attributed to the fast build-up and depletion of the hydration shell of PNIPMAM, caused by its hydrophobic moieties promoting a cooperative hydration character.}, language = {en} } @article{GlatzelNoackSchanzenbachetal.2020, author = {Glatzel, Julia and Noack, Sebastian and Schanzenbach, Dirk and Schlaad, Helmut}, title = {Anionic polymerization of dienes in 'green' solvents}, series = {Polymer international}, volume = {70}, journal = {Polymer international}, number = {2}, publisher = {Wiley}, address = {Hoboken}, issn = {0959-8103}, doi = {10.1002/pi.6152}, pages = {181 -- 184}, year = {2020}, abstract = {Isoprene and beta-myrcene were polymerized by anionic polymerization in bulk and in the 'green' ether solvents cyclopentyl methyl ether and 2-methyltetrahydrofuran and, for comparison, in cyclohexane and tetrahydrofuran. The polydienes produced in bulk and in cyclohexane contained high amounts of 1,4 units (>90\%) whereas those produced in ether solvents were rich in 1,2 and 3,4 units (36\%-86\%). Comparison of the microstructures and glass transition temperatures of the polydienes obtained in the various solvents suggests that conventionally used solvents can be substituted by environmentally more friendly alternatives.}, language = {en} } @article{MazareiPenschkeSaalfrank2023, author = {Mazarei, Elham and Penschke, Christopher and Saalfrank, Peter}, title = {Band gap engineering in two-dimensional materials by functionalization}, series = {ACS Omega}, volume = {8}, journal = {ACS Omega}, number = {24}, publisher = {American Chemical Society}, address = {Washington}, issn = {2470-1343}, doi = {10.1021/acsomega.3c02068}, pages = {22026 -- 22041}, year = {2023}, abstract = {Graphene is well-knownfor its unique combination of electricaland mechanical properties. However, its vanishing band gap limitsthe use of graphene in microelectronics. Covalent functionalizationof graphene has been a common approach to address this critical issueand introduce a band gap. In this Article, we systematically analyzethe functionalization of single-layer graphene (SLG) and bilayer graphene(BLG) with methyl (CH3) using periodic density functionaltheory (DFT) at the PBE+D3 level of theory. We also include a comparisonof methylated single-layer and bilayer graphene, as well as a discussionof different methylation options (radicalic, cationic, and anionic).For SLG, methyl coverages ranging from 1/8 to 1/1, (i.e.,the fully methylated analogue of graphane) are considered. We findthat up to a coverage theta of 1/2, graphene readily accepts CH3, with neighbor CH3 groups preferring trans positions. Above theta = 1/2, the tendency to accept further CH3 weakens and the lattice constant increases. The band gapbehaves less regularly, but overall it increases with increasing methylcoverage. Thus, methylated graphene shows potential for developingband gap-tuned microelectronics devices and may offer further functionalizationoptions. To guide in the interpretation of methylation experiments,vibrational signatures of various species are characterized by normal-modeanalysis (NMA), their vibrational density of states (VDOS), and infrared(IR) spectra, the latter two are obtained from ab initio moleculardynamics (AIMD) in combination with a velocity-velocity autocorrelationfunction (VVAF) approach.}, language = {en} } @misc{WolffCaprioglioStolterfohtetal.2019, author = {Wolff, Christian Michael and Caprioglio, Pietro and Stolterfoht, Martin and Neher, Dieter}, title = {Nonradiative recombination in perovskite solar cells}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {772}, issn = {1866-8372}, doi = {10.25932/publishup-43762}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437626}, pages = {20}, year = {2019}, abstract = {Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their VOC to values well below the Shockley-Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the VOC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome—paving the way to the thermodynamic efficiency limit.}, language = {en} } @article{ArboledaZapataGuillemoteauTronicke2022, author = {Arboleda-Zapata, Mauricio and Guillemoteau, Julien and Tronicke, Jens}, title = {A comprehensive workflow to analyze ensembles of globally inverted 2D electrical resistivity models}, series = {Journal of applied geophysics}, volume = {196}, journal = {Journal of applied geophysics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0926-9851}, doi = {10.1016/j.jappgeo.2021.104512}, pages = {12}, year = {2022}, abstract = {Electrical resistivity tomography (ERT) aims at imaging the subsurface resistivity distribution and provides valuable information for different geological, engineering, and hydrological applications. To obtain a subsurface resistivity model from measured apparent resistivities, stochastic or deterministic inversion procedures may be employed. Typically, the inversion of ERT data results in non-unique solutions; i.e., an ensemble of different models explains the measured data equally well. In this study, we perform inference analysis of model ensembles generated using a well-established global inversion approach to assess uncertainties related to the nonuniqueness of the inverse problem. Our interpretation strategy starts by establishing model selection criteria based on different statistical descriptors calculated from the data residuals. Then, we perform cluster analysis considering the inverted resistivity models and the corresponding data residuals. Finally, we evaluate model uncertainties and residual distributions for each cluster. To illustrate the potential of our approach, we use a particle swarm optimization (PSO) algorithm to obtain an ensemble of 2D layer-based resistivity models from a synthetic data example and a field data set collected in Loon-Plage, France. Our strategy performs well for both synthetic and field data and allows us to extract different plausible model scenarios with their associated uncertainties and data residual distributions. Although we demonstrate our workflow using 2D ERT data and a PSObased inversion approach, the proposed strategy is general and can be adapted to analyze model ensembles generated from other kinds of geophysical data and using different global inversion approaches.}, language = {en} } @article{KloseGuillemoteauVignolietal.2022, author = {Klose, Tim and Guillemoteau, Julien and Vignoli, Giulio and Tronicke, Jens}, title = {Laterally constrained inversion (LCI) of multi-configuration EMI data with tunable sharpness}, series = {Journal of applied geophysics}, volume = {196}, journal = {Journal of applied geophysics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0926-9851}, doi = {10.1016/j.jappgeo.2021.104519}, pages = {9}, year = {2022}, abstract = {Frequency-domain electromagnetic (FDEM) data are commonly inverted to characterize subsurface geoelectrical properties using smoothness constraints in 1D inversion schemes assuming a layered medium. Smoothness constraints are suitable for imaging gradual transitions of subsurface geoelectrical properties caused, for example, by varying sand, clay, or fluid content. However, such inversion approaches are limited in characterizing sharp interfaces. Alternative regularizations based on the minimum gradient support (MGS) stabilizers can, instead, be used to promote results with different levels of smoothness/sharpness selected by simply acting on the so-called focusing parameter. The MGS regularization has been implemented for different kinds of geophysical data inversion strategies. However, concerning FDEM data, the MGS regularization has only been implemented for vertically constrained inversion (VCI) approaches but not for laterally constrained inversion (LCI) approaches. We present a novel LCI approach for FDEM data using the MGS regularization for the vertical and lateral direction. Using synthetic and field data examples, we demonstrate that our approach can efficiently and automatically provide a set of model solutions characterized by different levels of sharpness and variable lateral consistencies. In terms of data misfit, the obtained set of solutions contains equivalent models allowing us also to investigate the non-uniqueness of FDEM data inversion.}, language = {en} } @misc{StolterfohtGrischekCaprioglioetal.2020, author = {Stolterfoht, Martin and Grischek, Max and Caprioglio, Pietro and Wolff, Christian Michael and Gutierrez-Partida, Emilio and Pe{\~n}a-Camargo, Francisco and Rothhardt, Daniel and Zhang, Shanshan and Raoufi, Meysam and Wolansky, Jakob and Abdi-Jalebi, Mojtaba and Stranks, Samuel D. and Albrecht, Steve and Kirchartz, Thomas and Neher, Dieter}, title = {How to quantify the efficiency potential of neat perovskite films}, 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 = {17}, issn = {1866-8372}, doi = {10.25932/publishup-51662}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-516622}, pages = {12}, year = {2020}, abstract = {Perovskite photovoltaic (PV) cells have demonstrated power conversion efficiencies (PCE) that are close to those of monocrystalline silicon cells; however, in contrast to silicon PV, perovskites are not limited by Auger recombination under 1-sun illumination. Nevertheless, compared to GaAs and monocrystalline silicon PV, perovskite cells have significantly lower fill factors due to a combination of resistive and non-radiative recombination losses. This necessitates a deeper understanding of the underlying loss mechanisms and in particular the ideality factor of the cell. By measuring the intensity dependence of the external open-circuit voltage and the internal quasi-Fermi level splitting (QFLS), the transport resistance-free efficiency of the complete cell as well as the efficiency potential of any neat perovskite film with or without attached transport layers are quantified. Moreover, intensity-dependent QFLS measurements on different perovskite compositions allows for disentangling of the impact of the interfaces and the perovskite surface on the non-radiative fill factor and open-circuit voltage loss. It is found that potassium-passivated triple cation perovskite films stand out by their exceptionally high implied PCEs > 28\%, which could be achieved with ideal transport layers. Finally, strategies are presented to reduce both the ideality factor and transport losses to push the efficiency to the thermodynamic limit.}, language = {en} } @article{StolterfohtGrischekCaprioglioetal.2020, author = {Stolterfoht, Martin and Grischek, Max and Caprioglio, Pietro and Wolff, Christian Michael and Gutierrez-Partida, Emilio and Pe{\~n}a-Camargo, Francisco and Rothhardt, Daniel and Zhang, Shanshan and Raoufi, Meysam and Wolansky, Jakob and Abdi-Jalebi, Mojtaba and Stranks, Samuel D. and Albrecht, Steve and Kirchartz, Thomas and Neher, Dieter}, title = {How to quantify the efficiency potential of neat perovskite films}, series = {Advanced Materials}, volume = {32}, journal = {Advanced Materials}, number = {17}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0935-9648}, doi = {10.1002/adma.202000080}, pages = {1 -- 10}, year = {2020}, abstract = {Perovskite photovoltaic (PV) cells have demonstrated power conversion efficiencies (PCE) that are close to those of monocrystalline silicon cells; however, in contrast to silicon PV, perovskites are not limited by Auger recombination under 1-sun illumination. Nevertheless, compared to GaAs and monocrystalline silicon PV, perovskite cells have significantly lower fill factors due to a combination of resistive and non-radiative recombination losses. This necessitates a deeper understanding of the underlying loss mechanisms and in particular the ideality factor of the cell. By measuring the intensity dependence of the external open-circuit voltage and the internal quasi-Fermi level splitting (QFLS), the transport resistance-free efficiency of the complete cell as well as the efficiency potential of any neat perovskite film with or without attached transport layers are quantified. Moreover, intensity-dependent QFLS measurements on different perovskite compositions allows for disentangling of the impact of the interfaces and the perovskite surface on the non-radiative fill factor and open-circuit voltage loss. It is found that potassium-passivated triple cation perovskite films stand out by their exceptionally high implied PCEs > 28\%, which could be achieved with ideal transport layers. Finally, strategies are presented to reduce both the ideality factor and transport losses to push the efficiency to the thermodynamic limit.}, language = {en} }