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216 results on '"Lieberwirth I"'

10. Encapsulation of Fe/Fe3O4 in carbon nanotubes grown over carbon nanofibers for high performance supercapacitor electrodes

Author

Arshad, S. N, Duran, Hatice, Lieberwirth, I., Aftab, Faryal, Ghafoor, S., Kirchhoff, K., Tanveer, S., Rehman, S. U., Arshad, S. N, Duran, Hatice, Lieberwirth, I., Aftab, Faryal, Ghafoor, S., Kirchhoff, K., Tanveer, S., and Rehman, S. U.

Abstract

Carbon-based supercapacitive materials are promising energy storage materials because of their high power density and long durability. The energy density of carbon based materials can be significantly improved by making their hybrids with metal/metal oxides and hydroxides. Here, we successfully fabricated the electrospun carbon nanofibers (CNFs) with Fe encapsulated carbon nanotubes (CNTs) by simple chemical vapor deposition (CVD). The Fe nanoparticles later got oxidized by absorbing oxygen from air resulting in the desired hierarchical Fe/Fe3O4 encapsulated CNT/CNF nanostructure (Fe/Fe3O4@CNT-CNF). The composite material showed a high specific capacitance of 195 F g-1 at 0.5 A g-1, areal capacitance of 398 m F cm-2 in 1 M KOH and long term durability with 95% capacitance retention even after 5000 charge discharge cycles. The findings of our results suggest that Fe/Fe3O4@CNT-CNF hybrid is a potential candidate for electrode material of an electrochemical capacitor due to its distinctive nanoarchitectures and physiochemical properties. © 2020 Elsevier B.V.

Published
2021

12. Defect engineering of polyethylene-like polyphosphoesters: Solid-state NMR characterization and surface chemistry of anisotropic polymer nanoplatelets

Author

Markwart, J., Suraeva, O., Haider, T., Lieberwirth, I., Graf, R., Wurm, F., and Sustainable Polymer Chemistry

Subjects
chemistry.chemical_classification, Condensation polymer, Polymers and Plastics, Organic Chemistry, UT-Hybrid-D, Chemical modification, Bioengineering, Polymer, Polyethylene, Biochemistry, law.invention, Crystal, chemistry.chemical_compound, Colloid, chemistry, Solid-state nuclear magnetic resonance, Chemical engineering, law, Crystallization
Abstract

Anisotropic materials with very high aspect ratios, such as nanoplatelets, are an exciting class of materials due to their unique properties based on their unilamellar geometry. Controlling their size and surface-functionality is challenging and has only be achieved in some cases for synthetic polymers. We present a general approach to prepare polymer-nanoplatelets with control over the lateral size and basal functionality, by simple polycondensation of precisely spaced and functional phosphate groups in polyethylene-like polymers. Because of the relatively large size of the phosphate groups, they are expelled from the bulk crystal to the basal surface. This allows to control the chain-folding during crystallization, which we analyzed via solid-state NMR and TEM. Furthermore, we present chemistry “on the surface” of the platelets: the pendant ester group at the phosphate offers the possibility to introduce functional groups accessible for further chemical modification on the crystal surface. This is shown by introducing a 2-acetylthioethyl ester group and subsequently cleaving this 2-acetylthioethyl ester group to the free P–OH. Together, these results render polyethylene-like polyphosphoesters a versatile platform for soft-matter nanoplatelets as functional colloids.

Published
2020

13. Der Einfluss von Intraokularlinsen-Kalzifikationen auf die optische Qualität von segmentalen multifokalen Intraokularlinsen

Author

Yildirim, TM, Labuz, G, Khoramnia, R, Son, HS, Lieberwirth, I, Schickhardt, SK, and Auffarth, GU

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Hintergrund: Intraokularlinsen (IOL)-Kalzifikationen sind eine seltene späte postoperative Komplikation bei Linsen aus hydrophilem Acrylat. In den letzten Jahren wurde vermehrt über Serien von Explantationen aufgrund dieser Pathologie berichtet. Ziel dieser Arbeit war es, den Einfluss der [zum vollständigen Text gelangen Sie über die oben angegebene URL], 34. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, interventionelle und refraktive Chirurgie

Published
2020
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16. Continuous-Flow Production of Perfluorocarbon-Loaded Polymeric Nanoparticles: From the Bench to Clinic

Author

Hoogendijk, E., Swider, E.A., Staal, A.H.J., White, P.B., Riessen, N.K. van, Glasser, G., Lieberwirth, I., Musyanovych, A., Serra, C.A., Srinivas, M., Koshkina, O., Hoogendijk, E., Swider, E.A., Staal, A.H.J., White, P.B., Riessen, N.K. van, Glasser, G., Lieberwirth, I., Musyanovych, A., Serra, C.A., Srinivas, M., and Koshkina, O.

Abstract

Contains fulltext : 229134.pdf (publisher's version ) (Open Access), Perfluorocarbon-loaded nanoparticles are powerful theranostic agents, which are used in the therapy of cancer and stroke and as imaging agents for ultrasound and (19)F magnetic resonance imaging (MRI). Scaling up the production of perfluorocarbon-loaded nanoparticles is essential for clinical translation. However, it represents a major challenge as perfluorocarbons are hydrophobic and lipophobic. We developed a method for continuous-flow production of perfluorocarbon-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles using a modular microfluidic system, with sufficient yields for clinical use. We combined two slit interdigital micromixers with a sonication flow cell to achieve efficient mixing of three phases: liquid perfluorocarbon, PLGA in organic solvent, and aqueous surfactant solution. The production rate was at least 30 times higher than with the conventional formulation. The characteristics of nanoparticles can be adjusted by changing the flow rates and type of solvent, resulting in a high PFC loading of 20-60 wt % and radii below 200 nm. The nanoparticles are nontoxic, suitable for (19)F MRI and ultrasound imaging, and can dissolve oxygen. In vivo (19)F MRI with perfluoro-15-crown-5 ether-loaded nanoparticles showed similar biodistribution as nanoparticles made with the conventional method and a fast clearance from the organs. Overall, we developed a continuous, modular method for scaled-up production of perfluorocarbon-loaded nanoparticles that can be potentially adapted for the production of other multiphase systems. Thus, it will facilitate the clinical translation of theranostic agents in the future.

Published
2020

19. Bewertung des posterior-edge Profils von hydrophoben Intraokularlinsen mittels Rasterelektronenmikroskopie

Author

Zhang, L, Labuz, G, Poompokawat, P, Lieberwirth, I, Merz, P, Khoramnia, R, and Auffarth, GU

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Zweck: Eine scharfe Optikkante wurde als wesentlicher Faktor zur Verhinderung der Entwicklung eines Nachstars (PCO) angesehen. In dieser Studie wollten wir die Abweichung eines perfekten Quadrats der Mikrokantenstruktur in verschiedenen hydrophoben Intraokularlinsen (IOLs) mithilfe der Rasterelektronenmikroskopie[zum vollständigen Text gelangen Sie über die oben angegebene URL], 33. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

Published
2019
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21. CeO2−x nanorods with intrinsic urease-like activity

Author

Korschelt, K., primary, Schwidetzky, R., additional, Pfitzner, F., additional, Strugatchi, J., additional, Schilling, C., additional, von der Au, M., additional, Kirchhoff, K., additional, Panthöfer, M., additional, Lieberwirth, I., additional, Tahir, M. N., additional, Hess, C., additional, Meermann, B., additional, and Tremel, W., additional

Published
2018
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23. Extraordinary Performance of Carbon-Coated Anatase TiO2 as Sodium-Ion Anode

Author

Tahir, M.N., Oschmann, B., Buchholz, D., Dou, X., Lieberwirth, I., Panthöfer, M., Tremel, W., Zentel, R., and Passerini, S.

Subjects
anatase TiO2, Technology, RAFT polymerization, carbon coating, sodium-ion batteries, nanoparticles, ddc:600
Abstract

The synthesis of in situ polymer-functionalized anatase TiO2 particles using an anchoring block copolymer with hydroxamate as coordinating species is reported, which yields nanoparticles (≈11 nm) in multigram scale. Thermal annealing converts the polymer brushes into a uniform and homogeneous carbon coating as proven by high resolution transmission electron microscopy and Raman spectroscopy. The strong impact of particle size as well as carbon coating on the electrochemical performance of anatase TiO2 is demonstrated. Downsizing the particles leads to higher reversible uptake/release of sodium cations per formula unit TiO2 (e.g., 0.72 eq. Na+ (11 nm) vs only 0.56 eq. Na+ (40 nm)) while the carbon coating improves rate performance. The combination of small particle size and homogeneous carbon coating allows for the excellent electrochemical performance of anatase TiO2 at high (134 mAh g−1 at 10 C (3.35 A g−1)) and low (≈227 mAh g−1 at 0.1 C) current rates, high cycling stability (full capacity retention between 2nd and 300th cycle at 1 C) and improved coulombic efficiency (≈99.8%).

Published
2016

25. Materialanalyse bei spontan luxierten, irisfixierten, phaken Intraokularlinsen

Author

Khoramnia, Ramin, Tandogan, T., Auffarth, G.U., Lieberwirth, I., and Holzer, M.P.

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Hintergrund: Die Luxation von phaken, irisfixierten Intraokularlinsen (IOL) ist eine seltene Komplikation. Wir berichten über die licht- und rasterelektronenmikroskopisch erhobenen Befunde bei spontan luxierten IOL vom Typ Artisan/Verisyse und Artiflex/Veriflex (Ophtec/AMO, Niederlande/USA).[for full text, please go to the a.m. URL], 29. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

Published
2015
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26. Biomaterialanalyse eines eingetrübten hydrophilen Intraokularlinsenmodells

Author

Khoramnia, Ramin, Tandogan, T., Lieberwirth, I., Wenzel, M., Hugger, P., and Auffarth, G.U.

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Hintergrund: Die Kalzifikation von hydrophilen IOL ist eine seltene Komplikation. Wir berichten über die licht- und rasterelektronenmikroskopisch erhobenen Befunde sowie die Röntgenspektroskopie bei eingetrübten IOL vom Typ Euromaxx ALI313Y (Argonoptics). Methoden: In unserem Labor[for full text, please go to the a.m. URL], 29. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

Published
2015

34. Hierarchical Self-Assembly and Dynamics of a Miktoarm Star chimera Composed of Poly(gamma-benzyl-L-glutamate), Polystyrene, and Polyisoprene

Author

Gitsas, A., Floudas, G., Mondeshki, M., Lieberwirth, I., Spiess, H. W., Iatrou, H., Hadjichristidis, N., and Hirao, A.

Subjects
functionalized polyphenylene dendrimers, block-copolymers, microphase separation, molecular-dynamics, triblock copolymers, diblock copolymers, rod, cross-polarization, solid-state, nmr
Abstract

The hierarchical self-assembly at the submicrometer, nanometer and alpha-helilcal length scales has been Studied in a miktoarm star rod-coil chimera composed of poly(gamma-benzyl-L-glutamate) (PBLG), polystyrene, and polyisoprene blocks by X-ray scattering, solid state NMR, and transmission electron microscopy. The propensity of the rod block toward alpha-helices that are further hexagonally packed gives rise to pure PBLG domains and induces the partial mixing of the two amorphous blocks. These structural results were confirmed by independent dynamic probes at the segmental and alpha-helical level by NMR and dielectric spectroscopy, respectively. Macromolecules

Published
2010

36. Hierarchical self-assembly of PDMA-b-PS chains into granular nanoparticles: Genesis and fate

Author

Bianchi, A, Mauri, M, Bonetti, S, Koynov, K, Kappl, M, Lieberwirth, I, Butt, H, Simonutti, R, BIANCHI, ALBERTO, MAURI, MICHELE, BONETTI, SIMONE, SIMONUTTI, ROBERTO, Bianchi, A, Mauri, M, Bonetti, S, Koynov, K, Kappl, M, Lieberwirth, I, Butt, H, Simonutti, R, BIANCHI, ALBERTO, MAURI, MICHELE, BONETTI, SIMONE, and SIMONUTTI, ROBERTO

Abstract

The hierarchical self-assembly of an amphiphilic block copolymer, poly( N,N-dimethylacrylamide)-block-polystyrene with a very short hydrophilic block (PDMA10-b-PS62), in large granular nanoparticles is reported. While these nanoparticles are stable in water, their disaggregation can be induced either mechanically (i.e., by applying a force via the tip of the cantilever of an atomic force microscope (AFM)) or by partial hydrolysis of the acrylamide groups. AFM force spectroscopy images show the rupture of the particle as a combination of collapse and flow, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of partly hydrolyzed nanoparticles provide a clear picture of the granular structure. (Chemical Equation Presented).

Published
2014

37. Thermodynamic confinement and alpha-helix persistence length in poly(gamma-benzyl-L-glutamate)-b-poly(dimethyl siloxane)-b-poly(gamma-benzyl-L-glutamate) triblock copolymers

Author

Papadopoulos, P., Floudas, G., Schnell, I., Lieberwirth, I., Nguyen, T. Q., and Klok, H. A.

Subjects
dielectric-dispersion, block-copolymers, polypeptide solutions, gamma-benzyl, molecular-dynamics, glass-transition, electric dipole moment, diblock copolymers, rod, solid-state
Abstract

The structure and the associated dynamics of a series of poly(y-benzyl-L-glutamate)-b-poly(dimethyl siloxane)b-poly(y-benzyl-L-glutamate) (PBLG-b-PDMS-b-PBLG) triblock copolymers were investigated using small- and wide-angle X-ray scattering, NMR, transmission electron microscopy, and dielectric spectroscopy, respectively. The structural analysis revealed phase separation in the case of the longer blocks with defected alpha-helical segments embedded within the block copolymer nanodomains. The alpha-helical persistence length was found to depend on the degree of segregation; thermodynamic confinement and chain stretching results in the partial annihilation of helical defects. Biomacromolecules

Published
2006

38. Thermal stability and enhanced thermoelectric properties of the tetragonal tungsten bronzes Nb8−xW9+xO47 (0 ＜ x ＜ 5).

Author

Cerretti, G., Balke, B., Panthöfer, M., Tremel, W., Schrade, M., Song, X., Norby, T., Lu, H., Weidner, T., and Lieberwirth, I.

Abstract

Thermoelectric materials are believed to play a fundamental role in the energy field over the next years thanks to their ability of directly converting heat into usable electric energy. To increase their integration in the commercial markets, improvements of the efficiencies are needed. At the same time, cheap and non-toxic materials are required along with easily upscalable production cycles. Compounds of the tetragonal tungsten bronze (TTB) series Nb8−xW9+xO47 fulfill all these requirements and are promising materials. Their adaptive structure ensures glass-like values of the thermal conductivity, and the substitution on the cation side allows a controlled manipulation of the electronic properties. In this contribution we report the stability study of the two highly substituted samples of the series, Nb5W12O47 (x = 3) and Nb4W13O47 (x = 4), when subjected to thermal cycling. Moreover, we show the results of the thermoelectric characterization of these samples. The two compounds have not been affected by the thermal treatment and showed an improvement of the thermoelectric performances up to a zT = 0.2 above 1000 K. [ABSTRACT FROM AUTHOR]

Published
2017
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41. Effect of Molecular Weight on the Structure and Crystallinity of Poly(3-hexylthiophene)

Author

Zen, A., Saphiannikova, M., Neher, D., Grenzer, J., Grigorian, S., Pietsch, U., Asawapirom, U., Janietz, S., Scherf, U., Lieberwirth, I., Wegner, G., Zen, A., Saphiannikova, M., Neher, D., Grenzer, J., Grigorian, S., Pietsch, U., Asawapirom, U., Janietz, S., Scherf, U., Lieberwirth, I., and Wegner, G.

Abstract

Recently, two different groups have reported independently, that the mobility of field-effect transistors made from regioregular poly(3-hexylthiophene) (P3HT) increases strongly with molecular weight. Two different models were presented, one proposing carrier trapping at grain boundaries and the second putting emphasis on different conformation and packing of the polymer chains in the thin layers. Here, we present the results of detailed investigations of powders and thin films of deuterated P3HT fractions with different molecular weight. For powder samples, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to investigate the structure and crystallization behaviors of the polymers. The GPC investigations show that all weight fractions possess a rather broad molecular weight distribution. DSC measurements revealed a strong decrease of the crystallization temperature and, most important, a significant decrease of the degree of crystallinity with decreasing molecular weight. In order to study the structure of thin layers in lateral and vertical directions, both transmission electron microscopy (TEM) and X-ray grazing incidence diffraction (GID) were utilized. These methods show that thin layers of the low molecular weight fraction consist of well-defined crystalline domains embedded in disordered matrix. In contrast, films of the high molecular weight fraction exhibit partially-ordered domains throughout the whole sample area. We propose that the transport properties of layers prepared from fractions of poly(3-hexylthiophene) with different molecular weight is largely determined by the crystallinity of the samples and not by the perfection of the packing of the chains in the individual crystallites.

Published
2006

42. Examination of laboratory-generated coated soot particles: An overview of the LACIS Experiment in November (LExNo) campaign

Author

Stratmann, F., primary, Bilde, M., additional, Dusek, U., additional, Frank, G. P., additional, Hennig, T., additional, Henning, S., additional, Kiendler-Scharr, A., additional, Kiselev, A., additional, Kristensson, A., additional, Lieberwirth, I., additional, Mentel, T. F., additional, Pöschl, U., additional, Rose, D., additional, Schneider, J., additional, Snider, J. R., additional, Tillmann, R., additional, Walter, S., additional, and Wex, H., additional

Published
2010
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49. Simple, One-Step Synthesis of Gold Nanowires in Aqueous Solution

Author

Vasilev, K., Zhu, T., Wilms, M., Gillies, G., Lieberwirth, I., Mittler, S., Knoll, W., and Kreiter, M.

Abstract

A simple procedure to synthesize gold nanowires based on the reduction of hydrogen tetrachloroaurate by 2-mercaptosuccinic acid in aqueous solution is presented. This procedure requires no additional capping or reduction agent and produces wires with an apparent curly morphology several micrometers in length with diameters as thin as 15 nm. Some of the wires produced end in a ribbonlike structure, finally terminated by a flat triangular prism. Investigations by scanning electron microscopy, transmission electron microscopy (bright and dark field), scanning transmission electron microscopy, and atomic force microscopy as well as conductivity measurements indicate fully connected, polycrystalline gold objects.

Published
2005

50. Petunia-Shaped Superstructures of CaCO<INF>3</INF> Aggregates Modulated by Modified Chitosan

Author

Liang, P., Shen, Q., Zhao, Y., Zhou, Y., Wei, H., Lieberwirth, I., Huang, Y., Wang, D., and Xu, D.

Abstract

This paper presents the crystallization behavior of calcium carbonate at the air/liquid interface of aqueous systems of carboxymethyl chitosan (CMCS) using the Kitano method. Although the synthesized CMCS (Mw ≈ 100 000) with 1.57 degree of carboxymethyl substitution shows no surface activity, it controls the crystallization of calcium carbonate to form a petunia-shaped superstructure. The shuttlecock-like head of this superstructure strongly supports Cölfen's opinion (Rudloff, J.; Cölfen, H. Langmuir 2004, 20, 991−996) for the existence of a gas template of CO2 bubbles temporarily captured by polymer molecules, while formation of the stem of this superstructure is provisionally attributed to the presence of the strong electrostatic interactions between calcium ions and the carboxylate groups. The CaCO3 superstructure and its morphology depend not only on the polymer concentration but also on the combined number of calcium ions per CMCS molecule. These results imply that this simple and versatile method expands the morphological investigation of mineralization processes.

Published
2004

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