TY - THES A1 - Leiterer, Jork T1 - Die Ultraschallfalle als analytisches Werkzeug N2 - Die Ultraschallfalle bietet eine besondere Möglichkeit zur Handhabung von Proben im Mikrolitermaßstab. Durch die akustische Levitation wird die Probe kontaktfrei in einer gasförmigen Umgebung positioniert und somit dem Einfluss fester Oberflächen entzogen. In dieser Arbeit werden die Möglichkeiten der Ultraschallfalle für den Einsatz in der Analytik experimentell untersucht. Durch die Kopplung mit typischen kontaktlosen Analysemethoden wie der Spektroskopie und der Röntgenstreuung werden die Vorteile dieser Levitationstechnik an verschiedenen Materialien wie anorganischen, organischen, pharmazeutischen Substanzen bis hin zu Proteinen, Nano- und Mikropartikeln demonstriert. Es wird gezeigt, dass die Nutzung der akustischen Levitation zuverlässig eine berührungslose Probenhandhabung für den Einsatz spektroskopischer Methoden (LIF, Raman) sowie erstmalig Methoden der Röntgenstreuung (EDXD, SAXS, WAXS) und Röntgenfluoreszenz (RFA, XANES) ermöglicht. Für alle genannten Methoden erwies sich die wandlose Probenhalterung als vorteilhaft. So sind die Untersuchungsergebnisse vergleichbar mit denen herkömmlicher Probenhalter und übertreffen diese teilweise hinsichtlich der Datenqualität. Einen besonderen Erfolg stellt die Integration des akustischen Levitators in die experimentellen Aufbauten der Messplätze am Synchrotron dar. Die Anwendung der Ultraschallfalle am BESSY konnte im Rahmen dieser Arbeit etabliert werden und bildet derzeit die Grundlage intensiver interdisziplinärer Forschung. Außerdem wurde das Potential der Falle zur Aufkonzentration erkannt und zum Studium verdunstungskontrollierter Prozesse angewendet. Die wandfreie und konzentrationsabhängige Untersuchung über einen Volumenbereich von drei Größenordnungen an derselben Probe ist eine einzigartige Möglichkeit. So konnte wesentlich zur Aufklärung von Fragestellungen der unterschiedlichen Forschungsgebiete beigetragen werden. Diese Untersuchungen sind die ersten in situ Studien der Agglomeration in einem akustisch levitierten Tropfen, angefangen von kleinen (an)organischen Molekülen über Proteine bis hin zu Nanopartikeln. Zusammenfassend eröffnen die Ergebnisse dieser Arbeit einen breiten Anwendungsbereich zur Benutzung der Ultraschallfalle als analytisches Werkzeug. T3 - BAM Dissertationsreihe - 46 KW - Akustische Levitation KW - Ultraschall KW - Tropfen KW - Analytik PY - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-1127 SN - 978-3-9812910-2-5 SN - 1613-4249 VL - 46 SP - 1 EP - 142 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-112 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leiterer, Jork A1 - Leitenberger, W. A1 - Emmerling, Franziska A1 - Thünemann, Andreas A1 - Panne, Ulrich T1 - The use of an acoustic levitator to follow crystallization in small droplets by energy-dispersive X-ray diffraction N2 - For the investigation of small sample volumes, the use of an acoustic levitator was tested as a `sample holder' for hovering droplets in a synchrotron beam. It might be advantageous to use levitated droplets instead of samples confined in solid holders, especially for the study of crystallization processes where the influence of containing walls has to be minimized. In a first experiment, the crystallization of sodium chloride in a small droplet of aqueous solution has been followed with a time resolution of 30 s. The collected diffraction peaks are compared with data in the ICSD database. KW - EDXD KW - Noncontact measurement technique KW - X-ray-scattering KW - Synchrotron-radiation KW - Acoustic levitation PY - 2006 U6 - https://doi.org/10.1107/S0021889806024915 SN - 0021-8898 SN - 1600-5767 VL - 39 IS - 5 SP - 771 EP - 773 PB - Blackwell CY - Oxford AN - OPUS4-13516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Thünemann, Andreas A1 - Panne, Ulrich T1 - The use of an acoustic levitator as a contactless sample holder N2 - Many of today’s analytical problems are characterized through small sample volumes and can only be solved through a corresponding miniaturisation of the analytical instrumentation. Handling of small sample volumes is inherently difficult due analytical blanks, contamination, and sorption processes on the walls of the containers which are employed during analytical procedures. Acoustic levitation is a powerful tool for contact-less sample handling of solid, liquid, and certain gaseous samples. In addition, levitation permits a chemical pre-treatment such as enrichment, extraction, and derivatisation as well as combination with other analytical techniques such as optical spectroscopy or mass spectrometry. Acoustically levitated liquid and solid samples are typically in a range between 0.005 - 5 µl (diameter 0.2 - 2 mm respectively) and are suspended in a gaseous environment by a stationary ultrasonic field (nodes of a standing wave). Acoustic levitation avoids sample contamination and sorption processes by container walls, but suffers from evaporation and loss of solvents. To balance evaporation and condensation on levitated drops during the experiments, techniques of contact-less droplet size monitoring and solvent and reagent supply have been developed. The advantages of acoustic levitation are demonstrated for on line analysis of crystallisation in a levitated droplet. The evaporation and formation of crystals is observed via time-resolved X-ray diffraction at BESSY. In this way, a high-throughput analysis for polymorphs seems feasible. Future work will be devoted to adaptation of a binding assay with receptors, antibodies or enzymes. Special emphasis will be on homogeneous immunoassays such as fluorescence polarisation immunoassays (FPIA) or apo-enzyme reactivation immunoassay systems (ARIS) combined with laser-induced fluorescence (LIF). This offers the opportunity to study the kinetics of the bio-macromolecule interactions without any wall effects which can have a significant influence on the apparent performance of bioanalytical assays. T2 - 1. Jahrestagung des Arbeitskreises Prozessanalytik der GDCh, BAM CY - Berlin, Germany DA - 2006-03-20 PY - 2006 AN - OPUS4-12250 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Thünemann, Andreas A1 - Panne, Ulrich T1 - Characterisation of levitated samples for modelling of condensed matter N2 - Many of today’s analytical problems are characterized by small sample volumes and can only be solved through a corresponding miniaturisation of the analytical instrumentation. Handling of small-sample volumes is inherently difficult due to contamination and sorption processes on the walls of containers. Acoustic levitation is a powerful tool for contact-free sample handling of solid, liquid, and selected gaseous samples. In addition, levitation permits a chemical pre-treatment such as enrichment, extraction, and derivatisation as well as combination with other analytical techniques such as optical spectroscopy. Acoustically levitated liquid and solid samples are typically in a range between 0.005-5 µl (diameter 0.2-2 mm respectively) and are suspended in a gaseous environment by a stationary ultrasonic field. Acoustic levitation avoids sample contamination and sorption processes by container walls, but suffers from evaporation and loss of solvents. Nonetheless, it is of great impact for the characterization of small samples. Exact determination of volume is inherently important to find out the resultant concentration in evaporating droplets. Levitation is a possibility to characterise the starting conditions of crystallisation and polymerisation. Even for spectroscopic methods the correct information on shape, size and concentration of samples are indispensable. To determine the size and volume of levitated samples, different methods of contactless droplet size monitoring were developed and compared in detail. They give the initial values for modelling of evaporation effects. In addition, for balancing evaporation and condensation on levitated drops during the experiments, non-contact techniques of solvent and reagent supply have been tested. Here, the advantages of acoustic levitation are demonstrated for on line analysis of crystallisation in a levitated droplet. The evaporation and formation of crystals is observed via time-resolved X-ray diffraction using synchrotron radiation at BESSY. Wall-free crystallisation in an acoustic levitator gives a tool to prove existing models concerning crystallisation processes. Furthermore the occurrence of polymorphic modifications depending on different conditions can be detected in situ under different and adjustable conditions. T2 - 13. Vortragstagung "Modellierung in der Festkörper- und Materialchemie" der GDCh-Fachgruppe Analytische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen CY - Aachen, Germany DA - 2006-09-20 PY - 2006 AN - OPUS4-13805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, S. E. A1 - Leiterer, Jork A1 - Pipich, V. A1 - Barrea, R. A1 - Emmerling, Franziska A1 - Tremel, W. T1 - Strong stabilization of amorphous calcium carbonate emulsion by ovalbumin: gaining insight into the mechanism of "polymer-induced liquid precursor" processes N2 - The impact of the ovo proteins ovalbumin and lysozyme—present in the first stage of egg shell formation—on the homogeneous formation of the liquid amorphous calcium carbonate (LACC) precursor, was studied by a combination of complementing methods: in situ WAXS, SANS, XANES, TEM, and immunogold labeling. Lysozyme (pI = 9.3) destabilizes the LACC emulsion whereas the glycoprotein ovalbumin (pI = 4.7) extends the lifespan of the emulsified state remarkably. In the light of the presented data: (a) Ovalbumin is shown to behave commensurable to the 'polymer-induced liquid precursor' (PILP) process proposed by Gower et al. Ovalbumin can be assumed to take a key role during eggshell formation where it serves as an effective stabilization agent for transient precursors and prevents undirected mineralization of the eggshell. (b) It is further shown that the emulsified LACC carries a negative surface charge and is electrostatically stabilized. (c) We propose that the liquid amorphous calcium carbonate is affected by polymers by depletion stabilization and de-emulsification rather than 'induced' by acidic proteins and polymers during a so-called polymer-induced liquid-precursor process. The original PILP coating effect, first reported by Gower et al., appears to be a result of a de-emulsification process of a stabilized LACC phase. The behavior of the liquid amorphous carbonate phase and the polymer-induced liquid-precursor phase itself can be well described by colloid chemical terms: electrostatic and depletion stabilization and de-emulsification by depletion destabilization. KW - Biomineralisation KW - Calcium carbonate KW - PILP KW - LACC PY - 2011 U6 - https://doi.org/10.1021/ja202622g SN - 0002-7863 SN - 1520-5126 VL - 133 IS - 32 SP - 12642 EP - 12649 PB - American Chemical Society CY - Washington, DC AN - OPUS4-24628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Delißen, Friedmar A1 - Emmerling, Franziska A1 - Thünemann, Andreas A1 - Panne, Ulrich T1 - Structure Analysis of Acoustically Levitated Droplets via Synchrotron X-ray Diffraction T2 - EUROANALYSIS-XIV CY - Antwerp, Belgium DA - 2007-09-09 PY - 2007 AN - OPUS4-15052 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Radnik, J. A1 - Armbruster, U. A1 - Bentrup, U. A1 - Martin, A. A1 - Brückner, A. T1 - In Droplet Monitoring of Catalytic Precursors Preparation T2 - 27 th Bessy User's Meeting CY - Berlin, Germany DA - 2008-12-06 PY - 2008 AN - OPUS4-18516 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Panne, Ulrich A1 - Rademann, K. A1 - Christen, W. T1 - In situ Studies of Caffeine Polymorph Crystal Formation by Droplet Evaporation T2 - 27h Bessy Users´ Meeting CY - Berlin, Germany DA - 2008-12-06 PY - 2008 AN - OPUS4-18520 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Wolf, S. E. A1 - Tremel, W. T1 - Ovalbumin Extends Dramatically the Lifespan of a Homogenous Amorphous CaCO3 Precursor - Amorphous Precursors During Formation of Calcium Carbonate Monitored via Contact-free in situ Synchrotron X-Ray Scattering Techniques T2 - Berliner Elektronenspeicherring-Gesellschaft für Synchrotonstrahlung m.b.H. (BESSY) CY - Berlin, Germany DA - 2008-12-06 PY - 2008 AN - OPUS4-18522 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Panne, Ulrich A1 - Tuckermann, R. T1 - Contactless handling of nanosized samples by acoustic levitation T2 - ANAKON 2007 - Tagung Fachgruppe Analytische Chemie der Gesellschaft Deutscher Chemiker, Friedrich-Schiller-Universität CY - Jena, Germany DA - 2007-03-27 PY - 2007 AN - OPUS4-14685 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Grabolle, Markus A1 - Rurack, Knut A1 - Panne, Ulrich A1 - Resch-Genger, Ute A1 - Ziegler, J. A1 - Nann, T. T1 - Fluorescence studies in acoustically levitated droplets T2 - ANAKON 2007 - Tagung Fachgruppe Analytische Chemie der Gesellschaft Deutscher Chemiker, Friedrich-Schiller-Universität CY - Jena, Germany DA - 2007-03-27 PY - 2007 AN - OPUS4-14686 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Grabolle, Markus A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Panne, Ulrich A1 - Ziegler, J. A1 - Nann, T. T1 - Acoustically levitated droplets - new sampling method for fluorescence studies T2 - Methods and Applications of Fluorescence (MAF), Congress Center CY - Salzburg, Austria DA - 2007-09-09 PY - 2007 AN - OPUS4-14698 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Radnik, J. A1 - Armbruster, U. A1 - Martin, A. T1 - New experimental setup for on-line monitoring of the synthesis of oxides at the µ-spot Beamline T2 - 26th BESSY Users' Meeting (Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung mbH) CY - Berlin, Germany DA - 2007-12-06 PY - 2007 AN - OPUS4-16401 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Thünemann, Andreas A1 - Panne, Ulrich T1 - Akustisch levitierte Tropfen für luftgetragene Analytik T2 - 1. Doktorandentagung - Arbeitskreise Chemometrik und Labordatenverarbeitung, Chemo- und Biosensoren, Prozessanalytik, Qualitätsmanagement und Elektro Analytische Chemie CY - Attendorn, Germany DA - 2007-02-08 PY - 2007 AN - OPUS4-16386 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leiterer, Jork A1 - Grabolle, Markus A1 - Rurack, Knut A1 - Resch-Genger, Ute A1 - Ziegler, J. A1 - Nann, T. A1 - Panne, Ulrich T1 - Acoustically Levitated Droplets - A Contactless Sampling Method for Fluorescence Studies N2 - Acoustic levitation is used as a newtool to study concentration-dependent processes influorescence spectroscopy. With this technique, small amounts of liquid and solid samples can be measured without the need for sample supports or containers, which often limits signal acquisition and can even alter sample properties due to interactions with the support material. We demonstrate that, because of the small sample volume, fluorescence measurements at high concentrations of an organic dye are possible without the limitation of inner-filter effects, which hamper such experiments in conventional, cuvette-based measurements. Furthermore, we show that acoustic levitation of liquid samples provides an experimentally simple way to study distance-dependent fluorescence modulations in semiconductor nanocrystals. The evaporation of the solvent during levitation leads to a continuous increase of solute concentration and can easily be monitored by laser-induced fluorescence. KW - Acoustic levitation KW - Dyes KW - Energy transfer KW - Fluorescence KW - Quantum dots KW - Nanocrystals KW - Ultrasonic trap PY - 2008 U6 - https://doi.org/10.1196/annals.1430.039 SN - 0077-8923 SN - 1749-6632 SN - 0094-8500 VL - 1130 SP - 78 EP - 84 PB - New York Academy of Sciences CY - New York, NY AN - OPUS4-17658 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Panne, Ulrich A1 - Christen, W. A1 - Rademann, K. T1 - Tracing Coffee Tabletop Traces N2 - Crystallization processes under different conditions are of fundamental interest in chemistry, pharmacy, and medicine. Therefore, we have studied the formation of micro- and nanosized crystals using water-caffeine (1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione) solutions under ambient conditions as a relevant model system. When droplets of an aqueous caffeine solution evaporate and eventually dry on surfaces (glass, polystyrene, and polyester), stable “coffee tabletop” rings with a perimeter of typically 3 mm are formed after 20 to 50 min. Using a micro focus X-ray beam available at the BESSY µSpot-beamline, the fine structure of different caffeine needles can be distinguished. Unexpectedly, both crystal modifications (α- and β-caffeine) are present, but locally separated in these rings. Furthermore, AFM studies reveal the presence of even smaller particles on a nanometer length scale. To eliminate influences of surface irregularities from the crystallization process, acoustic levitation of liquid samples was employed. Such levitated droplets are trapped in a stable position and only surrounded by air. The solvent in an ultrasonically levitated drop evaporates completely, and the resulting crystallization of caffeine was followed in situ by synchrotron X-ray diffraction. In this case, the diffraction pattern is in accordance with pure α-caffeine and does not indicate the formation of the room temperature polymorph β-caffeine. Hence, our investigations open new vistas that may lead to a controlled formation of cocrystals and novel polymorphs of micro- and nanocrystalline materials, which are of relevance for fundamental studies as well as for pharmaceutical and medical applications. KW - Polymorphism KW - Crystallization KW - Acoustic levitation KW - Evaporation of droplets KW - µSpot KW - Micro spot KW - Synchrotron radiation PY - 2008 U6 - https://doi.org/10.1021/la800768v SN - 0743-7463 SN - 1520-5827 VL - 24 IS - 15 SP - 7970 EP - 7978 PB - American Chemical Society CY - Washington, DC AN - OPUS4-17818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Panne, Ulrich A1 - Christen, W. A1 - Rademann, K. T1 - In situ studies of caffeine polymorph crystal formation by droplet evaporation T2 - Tag der Chemie und Innovationskongress Chemie und Biotechnologie CY - Berlin, Germany DA - 2008-04-23 PY - 2008 AN - OPUS4-17851 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bentrup, U. A1 - Radnik, J. A1 - Armbruster, U. A1 - Martin, A. A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Brückner, A. T1 - Linking simultaneous in situ WAXS/SAXS/Raman with Raman/ATR/UV-vis spectroscopy: comprehensive insight into the synthesis of molybdate catalyst precursors N2 - A new setup is presented which enables simultaneous wide- and small-angle X-ray scattering (WAXS/SAXS) and Raman spectroscopic experiments during the synthesis of Mo-based mixed oxide catalyst precursors at the µ-spot beamline at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung (BESSY). Furthermore, we report about the separate monitoring of the same reactions under comparable conditions by simultaneous combined ATR/UV–vis/Raman spectroscopic measurements. For testing the performance of both experimental setups two syntheses were described comprising the precipitation of metal molybdates by mixing solutions of metal nitrates and ammonium heptamolybdate. Additionally, the effect of H3PO4 admixture on precipitation was investigated. The combined evaluation of spectroscopic and WAXS/SAXS data allows the discrimination between different molybdate species appearing in solution and precipitate. Furthermore, these molybdate species could be assigned to separate phases of different crystallinity. KW - In situ KW - WAXS/SAXS KW - Raman KW - ATR KW - UV-vis KW - Mixed oxide catalyst KW - Synthesis PY - 2009 U6 - https://doi.org/10.1007/s11244-009-9309-y SN - 1022-5528 VL - 52 IS - 10 SP - 1350 EP - 1359 PB - Springer Science + Business Media CY - Dordrecht AN - OPUS4-19794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brandenburg, E. A1 - von Berlepsch, H. A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Koksch, B. T1 - Formation of alpha-helical nanofibers by mixing beta-structured and alpha-helical coiled coil peptides N2 - The helical coiled coil is a well-studied folding motif that can be used for the design of nanometer-sized bioinspired fibrous structures with potential applications as functional materials. A two-component system of coiled coil based model peptides is investigated, which forms, under acidic conditions, uniform, hundreds of nanometers long, and ~2.6 nm thick trimeric α-helical fibers. In the absence of the other component and under the same solvent conditions, one model peptide forms β-sheet-rich amyloid fibrils and the other forms stable trimeric α-helical coiled coils, respectively. These observations reveal that the complementary interactions driving helical folding are much stronger here than those promoting the intermolecular β-sheet formation. The results of this study are important in the context of amyloid inhibition but also open up new avenues for the design of novel fibrous peptidic materials. PY - 2012 U6 - https://doi.org/10.1021/bm300882d SN - 1525-7797 VL - 13 IS - 11 SP - 3542 EP - 3551 PB - ACS Publ. CY - Washington, DC, USA AN - OPUS4-27126 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - radnik, J. A1 - Bentrup, U. A1 - Brückner, A. T1 - Flying droplets as model system for spray drying - An in situ synchrotron X-ray scattering study on complex oxides catalyst precursors N2 - As a model for spray drying the early stages of crystallization of complex molybdate catalyst precursors were monitored online in droplets levitated acoustically. Synchron X-ray scattering techniques were applied to study the drying process of a typical molybdate catalysts precursor prepared from Ni-,Fe-,Bi-nitrate, ammonium heptamolybdate and H3PO4. Comparison with diffraction patterns obtained from sessile droplets shows significant differences in the crystal growth, whereas the final crystal structure – including a Keggin-type anion – is identical in both cases. The levitated samples exhibit a decelerated growth with a large number of small crystallites at the beginning of the crystallization, whereas in case of the sessile droplets a small number of large crystallites were observed after a few minutes. The acoustic levitation using an ultrasonic trap proves to be an elegant tool to mimic spray drying and offers new possibilities in relation to the understanding of the drying process. KW - Acoustic levitation KW - Spray drying KW - Molybdate catalysts KW - X-ray scattering PY - 2010 U6 - https://doi.org/10.1016/j.cattod.2009.11.001 SN - 0920-5861 VL - 155 IS - 3-4 SP - 326 EP - 330 PB - Elsevier CY - Amsterdam AN - OPUS4-21998 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, S. E. A1 - Müller, L. A1 - Barrea, R. A1 - Kampf, C.J. A1 - Leiterer, Jork A1 - Panne, Ulrich A1 - Hoffmann, T. A1 - Emmerling, Franziska A1 - Tremel, W. T1 - Carbonate-coordinated metal complexes precede the formation of liquid amorphous mineral emulsions of divalent metal carbonates N2 - During the mineralisation of metal carbonates MCO3 (M = Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed. PY - 2011 U6 - https://doi.org/10.1039/c0nr00761g SN - 2040-3364 SN - 2040-3372 IS - 3 SP - 1158 EP - 1165 PB - RSC Publ. CY - Cambridge AN - OPUS4-23355 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leiterer, Jork A1 - Panne, Ulrich A1 - Thünemann, Andreas A1 - Weidner, Steffen T1 - Container-less polymerization in acoustically levitated droplets: an analytical study by GPC and MALDI-TOF mass spectrometry N2 - Molecular masses and end groups of polystyrene (PS) formed in a novel container-less polymerization strategy, based on levitated droplets in an acoustic trap, were determined by Gel Permeation Chromatography (GPC) and Matrix-assisted Laser Desorption/Ionization Time of Flight Mass spectrometry (MALDI-TOF MS). KW - Ultraschallfalle KW - MALDI Massenspektrometrie KW - Polymerisation PY - 2011 U6 - https://doi.org/10.1039/c0ay00390e SN - 1759-9660 SN - 1759-9679 VL - 3 IS - 1 SP - 70 EP - 73 PB - RSC Publ. CY - Cambridge AN - OPUS4-23655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klimakow, Maria A1 - Leiterer, Jork A1 - Kneipp, Janina A1 - Rössler, E. A1 - Panne, Ulrich A1 - Rademann, K. A1 - Emmerling, Franziska T1 - Combined synchrotron XRD/Raman measurements: In situ identification of polymorphic transitions during crystallization processes N2 - A combination of two analytical methods, time-resolved X-ray diffraction (XRD) and Raman spectroscopy, is presented as a novel tool for crystallization studies. An acoustic levitator was employed as sample environment. This setup enables the acquisition of XRD and Raman data in situ simultaneously within a 20 s period and hence permits investigation of polymorphic phase transitions during the crystallization process in different solvents (methanol, ethanol, acetone, dichloromethane, acetonitrile). These real time measurements allow the determination of the phase content from the onset of the first crystalline molecular assemblies to the stable system. To evaluate the capability of this approach, the setup was applied to elucidate the crystallization process of the polymorphic compound nifedipine. The results indicate the existence of solvent-dependent transient phases during the crystallization process. The quality of the data allowed the assignment of the lattice constants of the hitherto unknown crystal structure of the β-polymorph. KW - Synchrotron radiation KW - XRD KW - Raman spectroscopy KW - Polymorphism KW - Crystallization KW - Acoustic levitation KW - Nifedipine PY - 2010 U6 - https://doi.org/10.1021/la100540q SN - 0743-7463 SN - 1520-5827 VL - 26 IS - 13 SP - 11233 EP - 11237 PB - American Chemical Society CY - Washington, DC AN - OPUS4-21396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Santos de Freitas, M. A1 - Araghi, R. R. A1 - Brandenburg, E. A1 - Leiterer, Jork A1 - Emmerling, Franziska A1 - Folmert, K. A1 - Gerling-Driessen, U. I. M. A1 - Bardiaux, B. A1 - Böttcher, C. A1 - Pagel, K. A1 - Diehl, A. A1 - v. Berlepsch, H. A1 - Oschkinat, H. A1 - Koksch, B. T1 - The protofilament architecture of a de novo designed coiled coil-based amyloidogenic peptide N2 - Amyloid fibrils are polymers formed by proteins under specific conditions and in many cases they are related to pathogenesis, such as Parkinson’s and Alzheimer’s diseases. Their hallmark is the presence of a β-sheet structure. High resolution structural data on these systems as well as information gathered from multiple complementary analytical techniques is needed, from both a fundamental and a pharmaceutical perspective. Here, a previously reported de novo designed, pH-switchable coiled coil-based peptide that undergoes structural transitions resulting in fibril formation under physiological conditions has been exhaustively characterized by transmission electron microscopy (TEM), cryo-TEM, atomic force microscopy (AFM), wide-angle X-ray scattering (WAXS) and solid-state NMR (ssNMR). Overall, a unique 2-dimensional carpet-like assembly composed of large coexisiting ribbon-like, tubular and funnel-like structures with a clearly resolved protofilament substructure is observed. Whereas electron microscopy and scattering data point somewhat more to a hairpin model of β-fibrils, ssNMR data obtained from samples with selectively labelled peptides are in agreement with both, hairpin structures and linear arrangements. KW - Amyloid KW - Elektronenmikroskopie PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-458713 UR - https://www.sciencedirect.com/science/article/pii/S1047847718301333 SN - 1047-8477 VL - 203 IS - 3 SP - 263 EP - 272 PB - Elsevier AN - OPUS4-45871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -