@misc{BuecheleChaoOstermannetal.2019,
  author    = {B{\"u}chele, Dominique and Chao, Madlen and Ostermann, Markus and Leenen, Matthias and Bald, Ilko},
  title     = {Multivariate chemometrics as a key tool for prediction of K and Fe in a diverse German agricultural soil-set using EDXRF},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {784},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43998},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-439988},
  pages     = {11},
  year      = {2019},
  abstract  = {Within the framework of precision agriculture, the determination of various soil properties is moving into focus, especially the demand for sensors suitable for in-situ measurements. Energy-dispersive X-ray fluorescence (EDXRF) can be a powerful tool for this purpose. In this study a huge diverse soil set (n = 598) from 12 different study sites in Germany was analysed with EDXRF. First, a principal component analysis (PCA) was performed to identify possible similarities among the sample set. Clustering was observed within the four texture classes clay, loam, silt and sand, as clay samples contain high and sandy soils low iron mass fractions. Furthermore, the potential of uni- and multivariate data evaluation with partial least squares regression (PLSR) was assessed for accurate determination of nutrients in German agricultural samples using two calibration sample sets. Potassium and iron were chosen for testing the performance of both models. Prediction of these nutrients in 598 German soil samples with EDXRF was more accurate using PLSR which is confirmed by a better overall averaged deviation and PLSR should therefore be preferred.},
  language  = {en}
}
@article{BuecheleChaoOstermannetal.2019,
  author    = {B{\"u}chele, Dominique and Chao, Madlen and Ostermann, Markus and Leenen, Matthias and Bald, Ilko},
  title     = {Multivariate chemometrics as a key tool for prediction of K and Fe in a diverse German agricultural soil-set using EDXRF},
  series = {Scientific Reports},
  volume    = {9},
  journal   = {Scientific Reports},
  publisher = {Macmillan Publishers Limited, part of Springer Nature},
  address   = {London},
  issn      = {2045-2322},
  doi       = {10.1038/s41598-019-53426-5},
  pages     = {11},
  year      = {2019},
  abstract  = {Within the framework of precision agriculture, the determination of various soil properties is moving into focus, especially the demand for sensors suitable for in-situ measurements. Energy-dispersive X-ray fluorescence (EDXRF) can be a powerful tool for this purpose. In this study a huge diverse soil set (n = 598) from 12 different study sites in Germany was analysed with EDXRF. First, a principal component analysis (PCA) was performed to identify possible similarities among the sample set. Clustering was observed within the four texture classes clay, loam, silt and sand, as clay samples contain high and sandy soils low iron mass fractions. Furthermore, the potential of uni- and multivariate data evaluation with partial least squares regression (PLSR) was assessed for accurate determination of nutrients in German agricultural samples using two calibration sample sets. Potassium and iron were chosen for testing the performance of both models. Prediction of these nutrients in 598 German soil samples with EDXRF was more accurate using PLSR which is confirmed by a better overall averaged deviation and PLSR should therefore be preferred.},
  language  = {en}
}
@misc{LiebigHenningSarhanetal.2019,
  author    = {Liebig, Ferenc and Henning, Ricky and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Schmitt, Clemens Nikolaus Zeno and Bargheer, Matias and Koetz, Joachim},
  title     = {A simple one-step procedure to synthesise gold nanostars in concentrated aqueous surfactant solutions},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {769},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43874},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-438743},
  pages     = {23633 -- 23641},
  year      = {2019},
  abstract  = {Due to the enhanced electromagnetic field at the tips of metal nanoparticles, the spiked structure of gold nanostars (AuNSs) is promising for surface-enhanced Raman scattering (SERS). Therefore, the challenge is the synthesis of well designed particles with sharp tips. The influence of different surfactants, i.e., dioctyl sodium sulfosuccinate (AOT), sodium dodecyl sulfate (SDS), and benzylhexadecyldimethylammonium chloride (BDAC), as well as the combination of surfactant mixtures on the formation of nanostars in the presence of Ag⁺ ions and ascorbic acid was investigated. By varying the amount of BDAC in mixed micelles the core/spike-shell morphology of the resulting AuNSs can be tuned from small cores to large ones with sharp and large spikes. The concomitant red-shift in the absorption toward the NIR region without losing the SERS enhancement enables their use for biological applications and for time-resolved spectroscopic studies of chemical reactions, which require a permanent supply with a fresh and homogeneous solution. HRTEM micrographs and energy-dispersive X-ray (EDX) experiments allow us to verify the mechanism of nanostar formation according to the silver underpotential deposition on the spike surface in combination with micelle adsorption.},
  language  = {en}
}
@article{LiebigHenningSarhanetal.2019,
  author    = {Liebig, Ferenc and Henning, Ricky and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Schmitt, Clemens Nikolaus Zeno and Bargheer, Matias and Koetz, Joachim},
  title     = {A simple one-step procedure to synthesise gold nanostars in concentrated aqueous surfactant solutions},
  series = {RSC Advances},
  volume    = {9},
  journal   = {RSC Advances},
  publisher = {RSC Publishing},
  address   = {London},
  issn      = {2046-2069},
  doi       = {10.1039/C9RA02384D},
  pages     = {23633 -- 23641},
  year      = {2019},
  abstract  = {Due to the enhanced electromagnetic field at the tips of metal nanoparticles, the spiked structure of gold nanostars (AuNSs) is promising for surface-enhanced Raman scattering (SERS). Therefore, the challenge is the synthesis of well designed particles with sharp tips. The influence of different surfactants, i.e., dioctyl sodium sulfosuccinate (AOT), sodium dodecyl sulfate (SDS), and benzylhexadecyldimethylammonium chloride (BDAC), as well as the combination of surfactant mixtures on the formation of nanostars in the presence of Ag⁺ ions and ascorbic acid was investigated. By varying the amount of BDAC in mixed micelles the core/spike-shell morphology of the resulting AuNSs can be tuned from small cores to large ones with sharp and large spikes. The concomitant red-shift in the absorption toward the NIR region without losing the SERS enhancement enables their use for biological applications and for time-resolved spectroscopic studies of chemical reactions, which require a permanent supply with a fresh and homogeneous solution. HRTEM micrographs and energy-dispersive X-ray (EDX) experiments allow us to verify the mechanism of nanostar formation according to the silver underpotential deposition on the spike surface in combination with micelle adsorption.},
  language  = {en}
}
@phdthesis{NaderiMehr2019,
  author    = {Naderi Mehr, Fatemeh},
  title     = {Preparation and self-assembly behavior of anisotropic polymer patchy particles},
  pages     = {74, XX},
  year      = {2019},
  language  = {en}
}
@phdthesis{Noack2019,
  author    = {Noack, Sebastian},
  title     = {Poly(lactide)-based amphiphilic block copolymers},
  doi       = {10.25932/publishup-43616},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436168},
  school      = {Universit{\"a}t Potsdam},
  pages     = {xvii, 148},
  year      = {2019},
  abstract  = {Due to its bioavailability and (bio)degradability, poly(lactide) (PLA) is an interesting polymer that is already being used as packaging material, surgical seam, and drug delivery system. Dependent on various parameters such as polymer composition, amphiphilicity, sample preparation, and the enantiomeric purity of lactide, PLA in an amphiphilic block copolymer can affect the self-assembly behavior dramatically. However, sizes and shapes of aggregates have a critical effect on the interactions between biological and drug delivery systems, where the general understanding of these polymers and their ability to influence self-assembly is of significant interest in science. The first part of this thesis describes the synthesis and study of a series of linear poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA)-based amphiphilic block copolymers with varying PLA (hydrophobic), and poly(ethylene glycol) (PEG) (hydrophilic) chain lengths and different block copolymer sequences (PEG-PLA and PLA-PEG). The PEG-PLA block copolymers were synthesized by ring-opening polymerization of lactide initiated by a PEG-OH macroinitiator. In contrast, the PLA-PEG block copolymers were produced by a Steglich-esterification of modified PLA with PEG-OH. The aqueous self-assembly at room temperature of the enantiomerically pure PLLA-based block copolymers and their stereocomplexed mixtures was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). Spherical micelles and worm-like structures were produced, whereby the obtained self-assembled morphologies were affected by the lactide weight fraction in the block copolymer and self-assembly time. The formation of worm-like structures increases with decreasing PLA-chain length and arises from spherical micelles, which become colloidally unstable and undergo an epitaxial fusion with other micelles. As shown by DSC experiments, the crystallinity of the corresponding PLA blocks increases within the self-assembly time. However, the stereocomplexed self-assembled structures behave differently from the parent polymers and result in irregular-shaped clusters of spherical micelles. Additionally, time-dependent self-assembly experiments showed a transformation, from already self-assembled morphologies of different shapes to more compact micelles upon stereocomplexation. In the second part of this thesis, with the objective to influence the self-assembly of PLA-based block copolymers and its stereocomplexes, poly(methyl phosphonate) (PMeP) and poly(isopropyl phosphonate) (PiPrP) were produced by ring-opening polymerization to implement an alternative to the hydrophilic block PEG. Although, the 1,8 diazabicyclo[5.4.0]unde 7 ene (DBU) or 1,5,7 triazabicyclo[4.4.0]dec-5-ene (TBD) mediated synthesis of the corresponding poly(alkyl phosphonate)s was successful, however, not so the polymerization of copolymers with PLA-based precursors (PLA-homo polymers, and PEG-PLA block copolymers). Transesterification, obtained by 1H-NMR spectroscopy, between the poly(phosphonate)- and PLA block caused a high-field shifted peak split of the methine proton in the PLA polymer chain, with split intensities depending on the used catalyst (DBU for PMeP, and TBD for PiPrP polymerization). An additional prepared block copolymer PiPrP-PLLA that wasn't affected in its polymer sequence was finally used for self-assembly experiments with PLA-PEG and PEG-PLA mixing. This work provides a comprehensive study of the self-assembly behavior of PLA-based block copolymers influenced by various parameters such as polymer block lengths, self-assembly time, and stereocomplexation of block copolymer mixtures.},
  language  = {en}
}
@misc{KirsteBrietzkeHoldtetal.2019,
  author    = {Kirste, Matthias and Brietzke, Thomas Martin and Holdt, Hans-J{\"u}rgen and Schilde, Uwe},
  title     = {The crystal structure of 1,12-diazaperylene, C₁₈H₁₀N₂},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {752},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43650},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436501},
  pages     = {3},
  year      = {2019},
  abstract  = {C₁₈H₁₀N₂, monoclinic, P2₁/c (no. 14), a=7.9297(9) {\AA}, b=11.4021(14) {\AA}, c=13.3572(15) {\AA}, β=105.363(8)°, V =1164.5(2) {\AA}³, Z =4, Rgt(F)=0.0325, wRref(F²)=0.0774, T =210(2) K.},
  language  = {en}
}
@article{KirsteBrietzkeHoldtetal.2019,
  author    = {Kirste, Matthias and Brietzke, Thomas Martin and Holdt, Hans-J{\"u}rgen and Schilde, Uwe},
  title     = {The crystal structure of 1,12-diazaperylene, C₁₈H₁₀N₂},
  series = {Zeitschrift f{\"u}r Kristallographie - New Crystal Structures},
  volume    = {234},
  journal   = {Zeitschrift f{\"u}r Kristallographie - New Crystal Structures},
  number    = {6},
  publisher = {De Gruyter},
  address   = {Berlin},
  issn      = {2196-7105},
  doi       = {10.1515/NCRS-2019-0385},
  pages     = {1255 -- 1257},
  year      = {2019},
  abstract  = {C₁₈H₁₀N₂, monoclinic, P2₁/c (no. 14), a=7.9297(9) {\AA}, b=11.4021(14) {\AA}, c=13.3572(15) {\AA}, β=105.363(8)°, V =1164.5(2) {\AA}³, Z =4, Rgt(F)=0.0325, wRref(F²)=0.0774, T =210(2) K.},
  language  = {en}
}
@misc{RajuLiebigHessetal.2019,
  author    = {Raju, Rajarshi Roy and Liebig, Ferenc and Hess, Andreas and Schlaad, Helmut and Koetz, Joachim},
  title     = {Temperature-triggered reversible breakdown of polymer-stabilized olive},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {751},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43646},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436461},
  pages     = {19271 -- 19277},
  year      = {2019},
  abstract  = {A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol\% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis.},
  language  = {en}
}
@article{RajuLiebigHessetal.2019,
  author    = {Raju, Rajarshi Roy and Liebig, Ferenc and Hess, Andreas and Schlaad, Helmut and Koetz, Joachim},
  title     = {Temperature-triggered reversible breakdown of polymer-stabilized olive},
  series = {RSC Advances},
  volume    = {9},
  journal   = {RSC Advances},
  number    = {35},
  publisher = {RSC Publishing},
  address   = {London},
  issn      = {2046-2069},
  doi       = {10.1039/c9ra03463c},
  pages     = {19271 -- 19277},
  year      = {2019},
  abstract  = {A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol\% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis.},
  language  = {en}
}
@phdthesis{Walczak2019,
  author    = {Walczak, Ralf},
  title     = {Molecular design of nitrogen-doped nanoporous noble carbon materials for gas adsorption},
  doi       = {10.25932/publishup-43524},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-435241},
  school      = {Universit{\"a}t Potsdam},
  pages     = {II, 155},
  year      = {2019},
  abstract  = {In den modernen Gesellschaften f{\"u}hrt ein stetig steigender Energiebedarf zu dem zunehmenden Verbrauch fossiler Brennstoffe wie Kohle, {\"O}l, und Gas. Die Verbrennung dieser kohlenstoffbasierten Brennstoffe f{\"u}hrt unweigerlich zur Freisetzung von Treibhausgasen, vor allem von CO2. Die CO2 Aufnahme unmittelbar bei den Verbrennungsanlagen oder direkt aus der Luft, zusammen mit Regulierung von CO2 produzierenden Energiesektoren (z.B. K{\"u}hlanlagen), k{\"o}nnen den CO2 Ausstoß reduzieren. Allerdings f{\"u}hren insbesondere bei der CO2 Aufnahme die geringen CO2 Konzentrationen und die Aufnahme konkurrierender Gase zu niedrigen CO2 Kapazit{\"a}ten und Selektivit{\"a}ten. Das Zusammenspiel der Gastmolek{\"u}le mit por{\"o}sen Materialien ist dabei essentiell. Por{\"o}se Kohlenstoffmaterialien besitzen attraktive Eigenschaften, unter anderem elektrische Leitf{\"a}higkeit, einstellbare Porosit{\"a}t, als auch chemische und thermische Stabilit{\"a}t. Allerdings f{\"u}hrt die zu geringe Polarisierbarkeit dieser Materialien zu einer geringen Affinit{\"a}t zu polaren Molek{\"u}len (z.B. CO2, H2O, oder NH3). Diese Affinit{\"a}t kann durch den Einbau von Stickstoff erh{\"o}ht werden. Solche Materialien sind oft „edler" als reine Kohlenstoffe, dies bedeutet, dass sie eher oxidierend wirken, als selbst oxidiert zu werden. Die Problematik besteht darin, einen hohen und gleichm{\"a}ßig verteilten Stickstoffgehalt in das Kohlenstoffger{\"u}st einzubauen. Die Zielsetzung dieser Dissertation ist die Erforschung neuer Synthesewege f{\"u}r stickstoffdotierte edle Kohlenstoffmaterialien und die Entwicklung eines grundlegenden Verst{\"a}ndnisses f{\"u}r deren Anwendung in Gasadsorption und elektrochemischer Energiespeicherung. Es wurde eine templatfreie Synthese f{\"u}r stickstoffreiche, edle, und mikropor{\"o}se Kohlenstoffmaterialien durch direkte Kondensation eines stickstoffreichen organischen Molek{\"u}ls als Vorl{\"a}ufer erarbeitet. Dadurch konnten Materialien mit hohen Adsorptionskapazit{\"a}ten f{\"u}r H2O und CO2 bei niedrigen Konzentrationen und moderate CO2/N2 Selektivit{\"a}ten erzielt werden. Um die CO2/N2 Selektivit{\"a}ten zu verbessern, wurden mittels der Einstellung des Kondensationsgrades die molekulare Struktur und Porosit{\"a}t der Kohlenstoffmaterialien kontrolliert. Diese Materialien besitzen die Eigenschaften eines molekularen Siebs f{\"u}r CO2 {\"u}ber N2, das zu herausragenden CO2/N2 Selektivit{\"a}ten f{\"u}hrt. Der ultrahydrophile Charakter der Porenoberfl{\"a}chen und die kleinen Mikroporen dieser Kohlenstoffmaterialien erm{\"o}glichen grundlegende Untersuchungen f{\"u}r die Wechselwirkungen mit Molek{\"u}len die polarer sind als CO2, n{\"a}mlich H2O und NH3. Eine weitere Reihe stickstoffdotierter Kohlenstoffmaterialien wurde durch Kondensation eines konjugierten mikropor{\"o}sen Polymers synthetisiert und deren strukturelle Besonderheiten als Anodenmaterial f{\"u}r die Natriumionen Batterie untersucht. Diese Dissertation leistet einen Beitrag zur Erforschung stickstoffdotierter Kohlenstoffmaterialien und deren Wechselwirkungen mit verschiedenen Gastmolek{\"u}len.},
  language  = {en}
}
@article{KruegerKellingLinkeretal.2019,
  author    = {Krueger, Tobias and Kelling, Alexandra and Linker, Torsten and Schilde, Uwe},
  title     = {Crystal structures of three cyclohexane‑based γ‑spirolactams},
  series = {BMC Chemistry},
  volume    = {13},
  journal   = {BMC Chemistry},
  number    = {69},
  publisher = {Springer International Publishing},
  address   = {Basel},
  issn      = {2661-801X},
  doi       = {10.1186/s13065-019-0586-7},
  pages     = {9},
  year      = {2019},
  abstract  = {The title compounds, 2-azaspiro[4.5]deca-1-one, C₉H₁₅NO, (1a), cis-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1b), and trans-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1c), were synthesized from benzoic acids 2 in only 3 steps in high yields. Crystallization from n-hexane afforded single crystals, suitable for X-ray diffraction. Thus, the configurations, conformations, and interesting crystal packing effects have been determined unequivocally. The bicyclic skeleton consists of a lactam ring, attached by a spiro junction to a cyclohexane ring. The lactam ring adopts an envelope conformation and the cyclohexane ring has a chair conformation. The main difference between compound 1b and compound 1c is the position of the carbonyl group on the 2-pyrrolidine ring with respect to the methyl group on the 8-position of the cyclohexane ring, which is cis (1b) or trans (1c). A remarkable feature of all three compounds is the existence of a mirror plane within the molecule. Given that all compounds crystallize in centrosymmetric space groups, the packing always contains interesting enantiomer-like pairs. Finally, the structures are stabilized by intermolecular N-H···O hydrogen bonds.},
  language  = {en}
}
@misc{KruegerKellingLinkeretal.2019,
  author    = {Krueger, Tobias and Kelling, Alexandra and Linker, Torsten and Schilde, Uwe},
  title     = {Crystal structures of three cyclohexane‑based γ‑spirolactams},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {738},
  doi       = {10.25932/publishup-43491},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-434911},
  pages     = {9},
  year      = {2019},
  abstract  = {The title compounds, 2-azaspiro[4.5]deca-1-one, C₉H₁₅NO, (1a), cis-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1b), and trans-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1c), were synthesized from benzoic acids 2 in only 3 steps in high yields. Crystallization from n-hexane afforded single crystals, suitable for X-ray diffraction. Thus, the configurations, conformations, and interesting crystal packing effects have been determined unequivocally. The bicyclic skeleton consists of a lactam ring, attached by a spiro junction to a cyclohexane ring. The lactam ring adopts an envelope conformation and the cyclohexane ring has a chair conformation. The main difference between compound 1b and compound 1c is the position of the carbonyl group on the 2-pyrrolidine ring with respect to the methyl group on the 8-position of the cyclohexane ring, which is cis (1b) or trans (1c). A remarkable feature of all three compounds is the existence of a mirror plane within the molecule. Given that all compounds crystallize in centrosymmetric space groups, the packing always contains interesting enantiomer-like pairs. Finally, the structures are stabilized by intermolecular N-H···O hydrogen bonds.},
  language  = {en}
}
@phdthesis{Tian2019,
  author    = {Tian, Zhihong},
  title     = {Oxygen-, Sulfur-doped Novel Porous Carbon-Nitrogen Frameworks by Salt Melt Method},
  school      = {Universit{\"a}t Potsdam},
  pages     = {101},
  year      = {2019},
  language  = {en}
}
@phdthesis{Lai2019,
  author    = {Lai, Feili},
  title     = {Functionalized ordered mesoporous carbon materials for enhancing the energy density of supercapacitors},
  school      = {Universit{\"a}t Potsdam},
  pages     = {115},
  year      = {2019},
  language  = {en}
}
@phdthesis{Sarhan2019,
  author    = {Sarhan, Radwan Mohamed},
  title     = {Plasmon-driven photocatalytic reactions monitored by surface-enhanced Raman spectroscopy},
  doi       = {10.25932/publishup-43330},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-433304},
  school      = {Universit{\"a}t Potsdam},
  year      = {2019},
  abstract  = {Plasmonic metal nanostructures can be tuned to efficiently interact with light, converting the photons into energetic charge carriers and heat. Therefore, the plasmonic nanoparticles such as gold and silver nanoparticles act as nano-reactors, where the molecules attached to their surfaces benefit from the enhanced electromagnetic field along with the generated energetic charge carriers and heat for possible chemical transformations. Hence, plasmonic chemistry presents metal nanoparticles as a unique playground for chemical reactions on the nanoscale remotely controlled by light. However, defining the elementary concepts behind these reactions represents the main challenge for understanding their mechanism in the context of the plasmonically assisted chemistry. Surface-enhanced Raman scattering (SERS) is a powerful technique employing the plasmon-enhanced electromagnetic field, which can be used for probing the vibrational modes of molecules adsorbed on plasmonic nanoparticles. In this cumulative dissertation, I use SERS to probe the dimerization reaction of 4-nitrothiophenol (4-NTP) as a model example of plasmonic chemistry. I first demonstrate that plasmonic nanostructures such as gold nanotriangles and nanoflowers have a high SERS efficiency, as evidenced by probing the vibrations of the rhodamine dye R6G and the 4-nitrothiophenol 4-NTP. The high signal enhancement enabled the measurements of SERS spectra with a short acquisition time, which allows monitoring the kinetics of chemical reactions in real time. To get insight into the reaction mechanism, several time-dependent SERS measurements of the 4-NTP have been performed under different laser and temperature conditions. Analysis of the results within a mechanistic framework has shown that the plasmonic heating significantly enhances the reaction rate, while the reaction is probably initiated by the energetic electrons. The reaction was shown to be intensity-dependent, where a certain light intensity is required to drive the reaction. Finally, first attempts to scale up the plasmonic catalysis have been performed showing the necessity to achieve the reaction threshold intensity. Meanwhile, the induced heat needs to quickly dissipate from the reaction substrate, since otherwise the reactants and the reaction platform melt. This study might open the way for further work seeking the possibilities to quickly dissipate the plasmonic heat generated during the reaction and therefore, scaling up the plasmonic catalysis.},
  language  = {en}
}
@phdthesis{RuizRodriguez2019,
  author    = {Ruiz Rodriguez, Janete Lorena},
  title     = {Osmotic pressure effects on collagen mimetic peptides},
  school      = {Universit{\"a}t Potsdam},
  pages     = {139},
  year      = {2019},
  abstract  = {Collagen is the most abundant protein in mammals. In many tissues, collagen molecules assemble to form a hierarchical structure. In the smallest supramolecular unit, named fibril, each molecule is displaced in the axial direction with respect to its neighbors. This staggering creates a periodic gap and overlap regions, where the gap regions exhibit 20\% less density. These fibril-forming collagens play an essential role in the strength of connective tissues. Despite much effort, directed at understanding collagen function and regulation, the influence of the chemical environment on the local structural and mechanical properties remains poorly understood. Recent studies, aimed at elucidating the effect of osmotic pressure, showed that collagen contracts upon water removal. This observation highlights the importance of water for the stabilization and mechanics of the collagen molecule. Using collagen mimetic peptides (CMPs), which fold into triple helical structures reminiscent of natural collagen, the primary goal of this work was to investigate the effect of the osmotic pressure on specific collagen-mimetic sequences. CMPs were used as the model system as they provide sequence control, which is essential for discriminating local from global structural changes and for relating the observed effects to existing knowledge about the full-length collagen molecule. Of specific interest was the structure of individual collagen triple helices as well as their organization into self-assembled higher order structures. These key structural features were monitored with infrared spectroscopy (IR) and synchrotron X-ray scattering, while varying the osmotic pressure. For controlling the osmotic pressure, CMP powder samples were incubated in air of defined relative humidity, ranging from dry conditions to highly "humid". In addition, to obtain more biologically relevant conditions, the CMPs were measured in ultrapure water and in solutions containing small molecule osmolytes. Using the sequences (Pro-Pro-Gly)10, (Pro-Hyp-Gly)10 and (Hyp-Hyp-Gly)10, it was shown that CMPs with different degrees of proline hydroxylation (Hyp = hydroxyproline) exhibit a sequence-specific response to osmotic pressure. IR spectroscopy revealed that osmotic pressure changes affect the strength of the triple helix stabilizing, interchain hydrogen bond and that the extent of this change depends on the degree of hydroxylation. X-ray scattering experiments further showed that changes in osmotic pressure affect both the molecular length as well as the higher order organization of CMPs. Starting from a pseudo-hexagonal packing in the dry state, all three CMPs showed isotropic swelling when increasing the water content to approximately 1.2 water molecules per amino acid, again to different extents depending on the degree of hydroxylation. When increasing the water content further, this pseudo-hexagonal arrangement breaks down. In the fully hydrated state, each CMP is characterized by its own specific and more complex packing geometry. While these changes in the lateral packing arrangement suggest swelling upon hydration, an overall decrease of the molecular length (i.e. contraction) was observed in the axial direction. Also for this structural feature, a strong dependency on the specific amino acid sequence was found. Interestingly, the observed contraction is the opposite of what has been reported for natural collagen. As (Pro-Pro-Gly)n, (Pro-Hyp-Gly)n and (Hyp-Hyp-Gly)n repeat units are found in collagen with a relatively high abundance, this suggests that other collagen sequence fragments need to respond to hydration in the opposite way to obtain a net elongation of the full-length collagen molecule. To test this hypothesis, sequences predicted to be sensitive to osmotic pressure were considered. One such sequence, consisting of two repeat units (Ala-Arg-Gly-Ser-Asp-Gly), was inserted as a guest into a (Pro-Pro-Gly) host. When compared to the canonical CMP sequences investigated earlier, the lateral helix packing follows a similar trend with increasing hydration; however, the host-guest CMP axially elongates with increasing water content. This behavior is more similar to what has been found for natural collagen and suggests that different sequences do determine the molecular length of collagen sequences differently. Interestingly, the canonical sequences are more abundant in the overlap region while the guest sequence is found in the gap region. This allows to speculate that sequences in the gap and overlap regions possess a specifically fine-tuned local response to osmotic pressure changes. Clearly, more experiments with additional sequences are needed to confirm this. In conclusion, the results obtained in this work indicate a highly sequence specific interaction between collagen and water. Osmotic pressure-induced conformational changes mostly originate from local geometries and bonding patterns and affect both the structure of individual triple helices as well as higher order assemblies. One key remaining question is how these conformational changes affect the local mechanical properties of the collagen molecule. As a first step, the stiffness (persistence length) of full-length collagen was determined using atomic force microscopy. In the future, experimental strategies need to be developed that allow for investigating the mechanical properties of specific collagen sequences, e.g. performing single-molecule force spectroscopy of CMPs.},
  language  = {en}
}
@phdthesis{Yan2019,
  author    = {Yan, Runyu},
  title     = {Nitrogen-doped and porous carbons towards new energy storage mechanisms for supercapacitors with high energy density},
  doi       = {10.25932/publishup-43141},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-431413},
  school      = {Universit{\"a}t Potsdam},
  pages     = {152},
  year      = {2019},
  abstract  = {Supercapacitors are electrochemical energy storage devices with rapid charge/discharge rate and long cycle life. Their biggest challenge is the inferior energy density compared to other electrochemical energy storage devices such as batteries. Being the most widely spread type of supercapacitors, electrochemical double-layer capacitors (EDLCs) store energy by electrosorption of electrolyte ions on the surface of charged electrodes. As a more recent development, Na-ion capacitors (NICs) are expected to be a more promising tactic to tackle the inferior energy density due to their higher-capacity electrodes and larger operating voltage. The charges are simultaneously stored by ion adsorption on the capacitive-type cathode surface and via faradic process in the battery-type anode, respectively. Porous carbon electrodes are of great importance in these devices, but the paramount problems are the facile synthetic routes for high-performance carbons and the lack of fundamental understanding of the energy storage mechanisms. Therefore, the aim of the present dissertation is to develop novel synthetic methods for (nitrogen-doped) porous carbon materials with superior performance, and to reveal a deeper understanding energy storage mechanisms of EDLCs and NICs. The first part introduces a novel synthetic method towards hierarchical ordered meso-microporous carbon electrode materials for EDLCs. The large amount of micropores and highly ordered mesopores endow abundant sites for charge storage and efficient electrolyte transport, respectively, giving rise to superior EDLC performance in different electrolytes. More importantly, the controversial energy storage mechanism of EDLCs employing ionic liquid (IL) electrolytes is investigated by employing a series of porous model carbons as electrodes. The results not only allow to conclude on the relations between the porosity and ion transport dynamics, but also deliver deeper insights into the energy storage mechanism of IL-based EDLCs which is different from the one usually dominating in solvent-based electrolytes leading to compression double-layers. The other part focuses on anodes of NICs, where novel synthesis of nitrogen-rich porous carbon electrodes and their sodium storage mechanism are investigated. Free-standing fibrous nitrogen-doped carbon materials are synthesized by electrospinning using the nitrogen-rich monomer (hexaazatriphenylene-hexacarbonitrile, C18N12) as the precursor followed by condensation at high temperature. These fibers provide superior capacity and desirable charge/discharge rate for sodium storage. This work also allows insights into the sodium storage mechanism in nitrogen-doped carbons. Based on this mechanism, further optimization is done by designing a composite material composed of nitrogen-rich carbon nanoparticles embedded in conductive carbon matrix for a better charge/discharge rate. The energy density of the assembled NICs significantly prevails that of common EDLCs while maintaining the high power density and long cycle life.},
  language  = {en}
}
@misc{HeckKanehiraKneippetal.2019,
  author    = {Heck, Christian and Kanehira, Yuya and Kneipp, Janina and Bald, Ilko},
  title     = {Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures},
  series = {Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Mathematisch-Naturwissenschaftliche Reihe},
  number    = {732},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-43081},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-430812},
  pages     = {10},
  year      = {2019},
  abstract  = {Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.},
  language  = {en}
}
@article{HeckKanehiraKneippetal.2019,
  author    = {Heck, Christian and Kanehira, Yuya and Kneipp, Janina and Bald, Ilko},
  title     = {Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures},
  series = {Molecules},
  volume    = {24},
  journal   = {Molecules},
  number    = {12},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {1420-3049},
  doi       = {10.3390/molecules24122324},
  pages     = {10},
  year      = {2019},
  abstract  = {Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.},
  language  = {en}
}
@phdthesis{Jiang2019,
  author    = {Jiang, Yi},
  title     = {Tailoring surface functions of micro/nanostructured polymeric substrates by thermo-mechanical treatments},
  school      = {Universit{\"a}t Potsdam},
  pages     = {93},
  year      = {2019},
  language  = {en}
}
@misc{AbbasVranicHoffmannetal.2019,
  author    = {Abbas, Ioana M. and Vranic, Marija and Hoffmann, Holger and El-Khatib, Ahmed H. and Montes-Bay{\´o}n, Mar{\´i}a and M{\"o}ller, Heiko Michael and Weller, Michael G.},
  title     = {Investigations of the Copper Peptide Hepcidin-25 by LC-MS/MS and NMR⁺},
  series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe},
  number    = {701},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42792},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427926},
  year      = {2019},
  abstract  = {Hepcidin-25 was identified as themain iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II) binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1\% ammonia. Further, mass spectrometry (tandemmass spectrometry (MS/MS), high-resolutionmass spectrometry (HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or referencematerial comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others.},
  language  = {en}
}
@phdthesis{AlNakeeb2019,
  author    = {Al Nakeeb, Noah},
  title     = {Self-assembly and crosslinking approaches of double hydrophilic linear-brush block copolymers},
  pages     = {133},
  year      = {2019},
  language  = {en}
}