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Murad A, Baron E, Feneberg M, Baumann M, Lehmann M, Eremin A. Polarity in Liquid Crystals Formed by Self-Assembled Umbrella-Shaped Subphthalocyanine Mesogens. ACS Appl Mater Interfaces 2024. [PMID: 38709679 DOI: 10.1021/acsami.4c01900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
We investigated the properties of p-type semiconducting columnar phases in self-assembled umbrella-shaped mesogens that have subphthalocyanine cores and oligo-thienyl arms. These compounds have nonswitchable phases that exhibit remanent electric polarization and nonlinear optical activity. Additionally, these compounds can generate photocurrents in the visible spectral range due to their wide absorption band. The photocurrent can be significantly increased by doping materials with fullerene. The charge mobility shows an anomalous field dependence, which decreases with the temperature.
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Affiliation(s)
- Ahmad Murad
- Institute of Physics, Otto von Guericke University, Magdeburg 39106, Germany
| | - Elias Baron
- Institute of Physics, Otto von Guericke University, Magdeburg 39106, Germany
| | - Martin Feneberg
- Institute of Physics, Otto von Guericke University, Magdeburg 39106, Germany
| | - Maximilian Baumann
- Institute of Organic Chemistry, University of Würzburg, Würzburg 97074, Germany
| | - Matthias Lehmann
- Institute of Physics, Otto von Guericke University, Magdeburg 39106, Germany
| | - Alexey Eremin
- Institute of Physics, Otto von Guericke University, Magdeburg 39106, Germany
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2
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Jarosik A, Nádasi H, Schwidder M, Manabe A, Bremer M, Klasen-Memmer M, Eremin A. Fluid fibers in true 3D ferroelectric liquids. Proc Natl Acad Sci U S A 2024; 121:e2313629121. [PMID: 38513103 PMCID: PMC10990086 DOI: 10.1073/pnas.2313629121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 02/08/2024] [Indexed: 03/23/2024] Open
Abstract
We demonstrate an exceptional ability of a high-polarization 3D ferroelectric liquid to form freely suspended fluid fibers at room temperature. Unlike fluid threads in modulated smectics and columnar phases, where translational order is a prerequisite for forming liquid fibers, recently discovered ferroelectric nematic forms fibers with solely orientational molecular order. Additional stabilization mechanisms based on the polar nature of the mesophase are required for this. We propose a model for such a mechanism and show that these fibers demonstrate an exceptional nonlinear optical response and exhibit electric field-driven instabilities.
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Affiliation(s)
- Alexander Jarosik
- Department of Nonlinear Phenomena, Institute of Physics, Otto von Guericke University, Magdeburg39106, Germany
| | - Hajnalka Nádasi
- Department of Nonlinear Phenomena, Institute of Physics, Otto von Guericke University, Magdeburg39106, Germany
| | - Michael Schwidder
- Department Industrial Chemistry, Institute of Chemistry, Otto von Guericke University, Magdeburg39106, Germany
| | | | | | | | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute of Physics, Otto von Guericke University, Magdeburg39106, Germany
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3
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Kuzminova A, Dmitrenko M, Salomatin K, Vezo O, Kirichenko S, Egorov S, Bezrukova M, Karyakina A, Eremin A, Popova E, Penkova A, Selyutin A. Holmium-Containing Metal-Organic Frameworks as Modifiers for PEBA-Based Membranes. Polymers (Basel) 2023; 15:3834. [PMID: 37765688 PMCID: PMC10534401 DOI: 10.3390/polym15183834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/04/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
Recently, there has been an active search for new modifiers to create hybrid polymeric materials for various applications, in particular, membrane technology. One of the topical modifiers is metal-organic frameworks (MOFs), which can significantly alter the characteristics of obtained mixed matrix membranes (MMMs). In this work, new holmium-based MOFs (Ho-MOFs) were synthesized for polyether block amide (PEBA) modification to develop novel MMMs with improved properties. The study of Ho-MOFs, polymers and membranes was carried out by methods of X-ray phase analysis, scanning electron and atomic force microscopies, Fourier transform infrared spectroscopy, low-temperature nitrogen adsorption, dynamic and kinematic viscosity, static and dynamic light scattering, gel permeation chromatography, thermogravimetric analysis and contact angle measurements. Synthesized Ho-MOFs had different X-ray structures, particle forms and sizes depending on the ligand used. To study the effect of Ho-MOF modifier on membrane transport properties, PEBA/Ho-MOFs membrane retention capacity was evaluated in vacuum fourth-stage filtration for dye removal (Congo Red, Fuchsin, Glycine thymol blue, Methylene blue, Eriochrome Black T). Modified membranes demonstrated improved flux and rejection coefficients for dyes containing amino groups: Congo Red, Fuchsin (PEBA/Ho-1,3,5-H3btc membrane possessed optimal properties: 81% and 68% rejection coefficients for Congo Red and Fuchsin filtration, respectively, and 0.7 L/(m2s) flux).
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Affiliation(s)
- Anna Kuzminova
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Mariia Dmitrenko
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Kirill Salomatin
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Olga Vezo
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Sergey Kirichenko
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Semyon Egorov
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Marina Bezrukova
- Institute of Macromolecular Compounds, Russian Academy of Sciences, 31 Bolshoy pr., St. Petersburg 199004, Russia; (M.B.); (A.E.); (E.P.)
| | - Anna Karyakina
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Alexey Eremin
- Institute of Macromolecular Compounds, Russian Academy of Sciences, 31 Bolshoy pr., St. Petersburg 199004, Russia; (M.B.); (A.E.); (E.P.)
| | - Ekaterina Popova
- Institute of Macromolecular Compounds, Russian Academy of Sciences, 31 Bolshoy pr., St. Petersburg 199004, Russia; (M.B.); (A.E.); (E.P.)
- Faculty of Chemical and Biotechnology, Organic Chemistry Department, Saint-Petersburg State Institute of Technology (Technical University), 24-26/49 Letter A Moskovski Ave., St. Petersburg 190013, Russia
- Faculty of Industrial Drug Technologies, Department of Chemical Technology of Medicinal Substances, Saint-Petersburg State Chemical and Pharmaceutical University, 14 Prof. Popova Str., St. Petersburg 197022, Russia
| | - Anastasia Penkova
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
| | - Artem Selyutin
- Saint-Petersburg State University, 7/9 Universitetskaya Emb., St. Petersburg 199034, Russia; (A.K.); (M.D.); (K.S.); (O.V.); (S.K.); (S.E.); (A.K.); (A.P.)
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von Rüling F, Alova A, Bulychev A, Eremin A. Intercellular permeation and cyclosis-mediated transport of a fluorescent probe in Characeae. Biophys J 2023; 122:419-432. [PMID: 36463405 PMCID: PMC9892610 DOI: 10.1016/j.bpj.2022.11.2948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/08/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Intercellular communication and transport is the essential prerequisite for the function of multicellular organisms. Simple diffusion as a transport mechanism is often inefficient in sustaining the effective exchange of metabolites, and other active transport mechanisms become involved. In this paper, we use the giant cells of characean algae as a model system to explore the role of advection and diffusion in intercellular transport. Using fluorescent dye as a tracer, we study the kinetics of the permeation of the fluorophore through the plasmodesmata complex in the node of tandem cells and its further distribution across the cell. To explore the role of cytoplasmic streaming and the nodal cell complex in the transport mechanism, we modulate the cytoplasmic streaming using action potential to separate the diffusive permeation from the advective contribution. The results imply that the plasmodesmal transport of fluorescent probe through the central and peripheral cells of the nodal complex is differentially regulated by a physiological signal, the action potential. The passage of the probe through the central cells of the nodal complex ceases transiently after elicitation of the action potential in the internodal cell, whereas the passage through the peripheral cells of the node was retained. A diffusion-advection model is developed to describe the transport kinetics and extract the permeability of the node-internode cell wall from experimental data.
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Affiliation(s)
- Florian von Rüling
- Department of Nonlinear Phenomena, Institute of Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Anna Alova
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexander Bulychev
- Department of Biophysics, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute of Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany.
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5
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Bulychev AA, Eremin A, von Rüling F, Alova AV. Effects of cell excitation on photosynthetic electron flow and intercellular transport in Chara. Protoplasma 2023; 260:131-143. [PMID: 35482255 DOI: 10.1007/s00709-022-01747-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
Impact of membrane excitability on fluidic transport of photometabolites and their cell-to-cell passage via plasmodesmata was examined by pulse-modulated chlorophyll (Chl) microfluorometry in Chara australis internodes exposed to dim background light. The cells were subjected to a series of local light (LL) pulses with a 3-min period and a 30-s pulse width, which induced Chl fluorescence transients propagating in the direction of cytoplasmic streaming along the photostimulated and the neighboring internodes. By comparing Chl fluorescence changes induced in the LL-irradiated and the adjoining internodes, the permeability of the nodal complex for the photometabolites was assessed in the resting state and after the action potential (AP) generation. The electrically induced AP had no influence on Chl fluorescence in noncalcified cell regions but disturbed temporarily the metabolite transport along the internode and caused a disproportionally strong inhibition of intercellular metabolite transmission. In chloroplasts located close to calcified zones, Chl fluorescence increased transiently after cell excitation, which indicated the deceleration of photosynthetic electron flow on the acceptor side of photosystem I. Functional distinctions of chloroplasts located in noncalcified and calcified cell areas were also manifested in different modes of LL-induced changes of Chl fluorescence, which were accompanied by dissimilar changes in efficiency of PSII-driven electron flow. We conclude that chloroplasts located near the encrusted areas and in the incrustation-free cell regions are functionally distinct even in the absence of large-scale variations of cell surface pH. The inhibition of transnodal transport after AP generation is probably due to Ca2+-regulated changes in plasmodesmal aperture.
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Affiliation(s)
| | - Alexey Eremin
- Institute of Physics, Otto-von-Guericke University, Magdeburg, Germany
| | | | - Anna V Alova
- Faculty of Biology, Moscow State University, Moscow, Russia.
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6
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Zavvou E, Klasen-Memmer M, Manabe A, Bremer M, Eremin A. Polarisation-driven magneto-optical and nonlinear-optical behaviour of a room-temperature ferroelectric nematic phase. Soft Matter 2022; 18:8804-8812. [PMID: 36354279 DOI: 10.1039/d2sm01298g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Nematics with a broken polar symmetry are one of the fascinating recent discoveries in the field of soft matter. High spontaneous polarisation and the fluidity of the ferroelectric nematic NF phase make such materials attractive for future applications and interesting for fundamental research. Here, we explore the polar and mechanical properties of a room-temperature ferroelectric nematic and its behaviour in a magnetic field. We show that NF is much less susceptible to the splay deformation than to the twist. The strong splay rigidity can be attributed to the electrostatic self-interaction of polarisation avoiding the polarisation splay.
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Affiliation(s)
- Evangelia Zavvou
- Otto von Guericke University Magdeburg, Institute of Physics, Dept. Nonlinear Phenomena, Magdeburg, Germany.
- Department of Physics, University of Patras, 26504, Patras, Greece
| | | | | | | | - Alexey Eremin
- Otto von Guericke University Magdeburg, Institute of Physics, Dept. Nonlinear Phenomena, Magdeburg, Germany.
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Eremin A, Murad A, Alaasar M. Shear-induced birefringence in an optically isotropic cubic liquid crystalline phase. Soft Matter 2022; 18:8315-8319. [PMID: 36300301 DOI: 10.1039/d2sm01148d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We report an unusually strong flow-induced birefringence in an optically isotropic cubic phase occurring below the isotropic chiral conglomerate phase formed by a low-molecular-weight polycatenar mesogen. The transition into the birefringent state occurs thresholdless and the induced birefringence is comparable with that observed in polymeric systems. We suggest that the flow-induced deformation of the cubic structure is responsible for the strong rheo-optical response.
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Affiliation(s)
- Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Physics Otto von Guericke University Magdeburg, Magdeburg, Germany.
| | - Ahmad Murad
- Department of Nonlinear Phenomena, Institute for Physics Otto von Guericke University Magdeburg, Magdeburg, Germany.
| | - Mohamed Alaasar
- Department of Chemistry, Martin-Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.
- Department of Chemistry, Cairo University, Giza, Egypt.
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Küster M, Ludwig F, Eremin A, Boštjančič PH, Lisjak D, Sebastián N, Mertelj A, Nádasi H. Magnetic dynamics in suspensions of ferrimagnetic platelets. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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9
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Koch K, Kundt M, Barkane A, Nadasi H, Webers S, Landers J, Wende H, Eremin A, Schmidt AM. Superparamagnetic nanoparticles with LC polymer brush shell as efficient dopants for ferronematic phases. Phys Chem Chem Phys 2021; 23:24557-24569. [PMID: 34755719 DOI: 10.1039/d1cp03005a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Liquid crystal (LC) based magnetic materials consisting of LC hosts doped with functional magnetic nanoparticles enable optical switching of the mesogens at moderate magnetic field strengths and thereby open the pathway for the design of novel smart devices. A promising route for the fabrication of stable ferronematic phases is the attachment of a covalently bound LC polymer shell onto the surface of nanoparticles. With this approach, ferronematic phases based on magnetically blocked particles and the commercial LC 4-cyano-4'-pentylbiphenyl (5CB) liquid crystal were shown to have a sufficient magnetic sensitivity, but the mechanism of the magneto-nematic coupling is unidentified. To get deeper insight into the coupling modes present in these systems, we prepared ferronematic materials based on superparamagnetic particles, which respond to external fields with internal magnetic realignment instead of mechanical rotation. This aims at clarifying whether the hard coupling of the magnetization to the particle's orientation (magnetic blocking) is a necessary component of the magnetization-nematic director coupling mechanism. We herein report the fabrication of a ferronematic phase consisting of surface-functionalized superparamagnetic Fe3O4 particles and 5CB. We characterize the phase behavior and investigate the magneto-optical properties of the new ferronematic phase and compare it to the ferronematic system containing magnetically blocked CoFe2O4 particles to get information about the origin of the magneto-nematic coupling.
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Affiliation(s)
- Karin Koch
- Universität zu Köln, Department Chemie, Institut für Physikalische Chemie, Luxemburger Str. 116, D-50939 Köln, Germany.
| | - Matthias Kundt
- Universität zu Köln, Department Chemie, Institut für Physikalische Chemie, Luxemburger Str. 116, D-50939 Köln, Germany.
| | - Anda Barkane
- Universität zu Köln, Department Chemie, Institut für Physikalische Chemie, Luxemburger Str. 116, D-50939 Köln, Germany.
| | - Hajnalka Nadasi
- Otto-von-Guericke-Universität Magdeburg, Institut für Physik, Universitätsplatz 2, D-39016 Magdeburg, Germany
| | - Samira Webers
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Duisburg, Germany
| | - Joachim Landers
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Duisburg, Germany
| | - Heiko Wende
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, Duisburg, Germany
| | - Alexey Eremin
- Otto-von-Guericke-Universität Magdeburg, Institut für Physik, Universitätsplatz 2, D-39016 Magdeburg, Germany
| | - Annette M Schmidt
- Universität zu Köln, Department Chemie, Institut für Physikalische Chemie, Luxemburger Str. 116, D-50939 Köln, Germany.
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Lipatova T, Malinova L, Eremin A. Behavioral economics strategies for promoting adherence to treatment in heart failure patients. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.3121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Heart failure (HF) is characterized by an increased risk of both fatal and nonfatal adverse cardiovascular events, which required life-long and costly treatment. At the same time every cardiology practitioner is well aware, that despite huge efforts on patient's education there remains a substantial part of patients who do not always make rational choices regarding their treatment. Patient's knowledge does not always translate into adherence, so we must find ways to minimize the intent-behavior gap to improve the efficacy of HF treatment. We presume that behavioral economics can provide us with tools that will promote positive present behavior of patients.
The purpose of the study was to examine the utility of behavioral economics-related concepts in understanding long-term treatment strategy in heart failure patients and acute heart failure survivors.
Methods
We performed an open prospective study involving male patients with both chronic and acute heart failure (CHF n=65 and AHF n=54). Involved patients were surveyed on symptom severity, behavioral economics “parameters”. Cognitive complexity was measured via “real life” case simulations. We assessed stress and depression with HADS and Zung's scales serially: on admission, 3d day of hospitalization and day before discharge. In patients with AHF, first assessment was performed after clinical stabilization. The primary outcomes were set as an adherence to prescribed medication assessed 6 and 36 months after discharge, rehospitalization due to cardiovascular reasons and self-assessed well-being.
Results
We observed opposite patterns of stress dynamics in CHF and AHF groups. AHF patients demonstrated significant reduction of stress level on the 3d day since admission: 9.0 (7.1; 9.9) vs 6.4 (5.7; 7.4) units, p=0.037, with further increase at discharge, while in CHF patients there was tendency to significant change in parameter was absent.
Patients who survived AHF demonstrated higher 6 month adherence to prescribed medication (62.9% vs 49.2%, p=0.047), at the same time there was the strong positive correlation between medication's price and self-induced therapy interruption (R=0.74, p<0.05). Both AHF and CHF reported financial planning as the major contributor for decision making in “real life” cases. Surprisingly in study population self-assessed well-being did not correlated with rehospitalization rate.
Parameters that were significantly associated with CV rehospitalization included symptoms at admission (OR 2.1 CI 1.4; 3.2, p=0.002), regularly saving money (OR =2.7 CI 1.9; 4.6, p=0.001) and stress level at discharge (OR 1.6 CI 1.1; 2.4, p=0.027).
Conclusion
Received results may be useful to identify heart failure patients at higher risk of self-induced treatment interruption. These patients could be offered focused support and counseling designed to enhance adherence to prescribed medication in order to improve long-term heart failure outcomes.
Funding Acknowledgement
Type of funding sources: None.
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Affiliation(s)
- T Lipatova
- Saratov State Medical University, Saratov, Russian Federation
| | - L Malinova
- Saratov State Medical University, Saratov, Russian Federation
| | - A Eremin
- Saratov State Medical University, Saratov, Russian Federation
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Kang K, Eremin A. Solvent-dependent morphology and anisotropic microscopic dynamics of cellulose nanocrystals under electric fields. Phys Rev E 2021; 103:032606. [PMID: 33862807 DOI: 10.1103/physreve.103.032606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/03/2021] [Indexed: 11/07/2022]
Abstract
Cellulose nanocrystals (CNCs) are interesting for the construction of biomaterials for energy delivery and packaging purposes. The corresponding processing of CNCs can be optimized through the variation of intercellulose interactions by employing different types of solvents, and thereby varying the degree of cellulose hydrogen bonding. The aim of this work is (i) to show how different types of solvents affect the self-assembled morphology of CNCs, (ii) to study the microscopic dynamics and averaged orientations on the CNCs in aqueous suspensions, including the effect of externally imposed electric fields, and (iii) to explore the nonlinear optical response of CNCs. The homogeneity of self-assembled chiral-nematic phase depends on both the polarity of the solvent and the CNC concentration. The variation of the chiral-nematic pitch length with concentration, as determined from real-space and Fourier images, is found to be strongly solvent dependent. The anisotropic microdynamics of CNCs suspension exhibits two modes, related to diffusion parallel and perpendicular to the (chiral-) nematic director. We have found also the coupling between translational and orientational motion, due to existing correlation length of twisted nematic elasticity. Preliminary second-harmonic generation experiments are performed, which reveal that relatively high field strengths are required to reorient chiral-nematic domains of CNCs.
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Affiliation(s)
- Kyongok Kang
- Forschungszentrum Jülich, Institute of Biological Information Processing, IBI-4:Biomacromolecular Systems and Processes, Jülich 52428, Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Güricke University Magdeburg, Magdeburg 39016, Germany
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Abstract
Coalescence of droplets plays a crucial role in nature and modern technology. Various experimental and theoretical studies explored droplet dynamics in three-dimensional (3D) and on 2D solid or liquid substrates. In this paper, we demonstrate the complete coalescence of isotropic droplets in thin quasi-2D liquids-overheated smectic films. We observe the merging of micrometer-sized flat droplets using high-speed imaging and analyze the shape transformations of the droplets on the timescale of milliseconds. Our studies reveal the scaling laws of the coalescence time, which exhibits a different dependence on the droplet geometry from that in the case of droplets on a solid substrate. A theoretical model is proposed to explain the difference in behavior.
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Affiliation(s)
- Christoph Klopp
- Institute of Physics, Department of Nonlinear Phenomena, Otto von Guericke University, Magdeburg 39106, Germany
| | - Alexey Eremin
- Institute of Physics, Department of Nonlinear Phenomena, Otto von Guericke University, Magdeburg 39106, Germany
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Kurachkina M, Nádasi H, Alaasar M, Tschierske C, Eremin A. Photomanipulation of the Mechanical Properties in a Liquid Crystal with Azo‐Containing Bent‐Core Mesogens. CHEMPHOTOCHEM 2020. [DOI: 10.1002/cptc.202000125] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Hajnalka Nádasi
- Otto von Guericke University Inst. of Physics 39016 Magdeburg Germany
| | - Mohamed Alaasar
- Martin Luther University Halle-Wittenberg Kurt Mothes Str. 2 D-06120 Halle (Saale) Germany
- Department of Chemistry Faculty of Science Cairo University Giza Egypt
| | - Carsten Tschierske
- Martin Luther University Halle-Wittenberg Kurt Mothes Str. 2 D-06120 Halle (Saale) Germany
| | - Alexey Eremin
- Otto von Guericke University Inst. of Physics 39016 Magdeburg Germany
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Bakhchova L, Jonušauskas L, Andrijec D, Kurachkina M, Baravykas T, Eremin A, Steinmann U. Femtosecond Laser-Based Integration of Nano-Membranes into Organ-on-a-Chip Systems. Materials (Basel) 2020; 13:ma13143076. [PMID: 32664211 PMCID: PMC7412128 DOI: 10.3390/ma13143076] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/04/2020] [Accepted: 07/08/2020] [Indexed: 12/23/2022]
Abstract
Organ-on-a-chip devices are gaining popularity in medical research due to the possibility of performing extremely complex living-body-resembling research in vitro. For this reason, there is a substantial drive in developing technologies capable of producing such structures in a simple and, at the same time, flexible manner. One of the primary challenges in producing organ-on-chip devices from a manufacturing standpoint is the prevalence of layer-by-layer bonding techniques, which result in limitations relating to the applicable materials and geometries and limited repeatability. In this work, we present an improved approach, using three dimensional (3D) laser lithography for the direct integration of a functional part-the membrane-into a closed-channel system. We show that it allows the freely choice of the geometry of the membrane and its integration into a complete organ-on-a-chip system. Considerations relating to sample preparation, the writing process, and the final preparation for operation are given. Overall, we consider that the broader application of 3D laser lithography in organ-on-a-chip fabrication is the next logical step in this field's evolution.
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Affiliation(s)
- Liubov Bakhchova
- Institute for Automation Engineering, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany;
- Correspondence: ; Tel.: +49-39-1675-7238
| | - Linas Jonušauskas
- Femtika Ltd., LT-10224 Vilnius, Lithuania; (L.J.); (D.A.); (T.B.)
- Laser Research Center, Vilnius University, LT-10223 Vilnius, Lithuania
| | - Dovilė Andrijec
- Femtika Ltd., LT-10224 Vilnius, Lithuania; (L.J.); (D.A.); (T.B.)
| | - Marharyta Kurachkina
- Institute of Physics, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany; (M.K.); (A.E.)
| | - Tomas Baravykas
- Femtika Ltd., LT-10224 Vilnius, Lithuania; (L.J.); (D.A.); (T.B.)
| | - Alexey Eremin
- Institute of Physics, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany; (M.K.); (A.E.)
| | - Ulrike Steinmann
- Institute for Automation Engineering, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany;
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15
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Abstract
Switching of liquid crystal phases is of enormous technological importance and enables digital displays, thermometers and sensors.
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Affiliation(s)
- Karin Koch
- Universität zu Köln
- Department Chemie
- Institut für Physikalische Chemie
- D-50939 Köln
- Germany
| | - Matthias Kundt
- Universität zu Köln
- Department Chemie
- Institut für Physikalische Chemie
- D-50939 Köln
- Germany
| | - Alexey Eremin
- Otto-von-Guericke-Universität Magdeburg
- Institut für Physik
- D-39016 Magdeburg
- Germany
| | - Hajnalka Nadasi
- Otto-von-Guericke-Universität Magdeburg
- Institut für Physik
- D-39016 Magdeburg
- Germany
| | - Annette M. Schmidt
- Universität zu Köln
- Department Chemie
- Institut für Physikalische Chemie
- D-50939 Köln
- Germany
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16
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Eremin A. 15th European liquid crystal conference 2019 in Wrocław. Liquid Crystals Today 2019. [DOI: 10.1080/1358314x.2019.1693094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Alexey Eremin
- Otto von Guericke University, Institute of Physics, Magdeburg, Germany,
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17
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Usadel KD, Storozhenko A, Arefyev I, Nádasi H, Trittel T, Stannarius R, Veit P, Eremin A. Frequency-dependent conversion of the torque of a rotating magnetic field on a ferrofluid confined in a spherical cavity. Soft Matter 2019; 15:9018-9030. [PMID: 31675052 DOI: 10.1039/c9sm01311c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The dynamics of magnetic nanoparticles in rotating magnetic fields is studied both experimentally and theoretically. The experimental investigation is focused on the conversion of the magnetic forces to a mechanical torque acting on a ferrofluid confined in a spherical cavity in a rotating magnetic field. Polydispersity usually present in diluted ferrofluids is shown to play a crucial role in the torque conversion. Important features observed experimentally are reproduced theoretically in studies on the dynamics of particles with uniaxial magnetic anisotropy in the presence of thermal noise. The phase lag between the rotating magnetic field and the induced rotating magnetization, as well as the corresponding torque which is transferred to the carrier fluid because of the mutual coupling between both, is analyzed as a function of the particle size. It is shown that for large particles the magnetic moment is locked to the anisotropy axis. On lowering the particle radius, Néel relaxation becomes increasingly important. Illustrative numerical calculations demonstrating this behavior are performed for magnetic parameters typical for iron oxide.
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Affiliation(s)
- Klaus D Usadel
- Theoretische Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany
| | | | - Igor Arefyev
- Ivanovo State Power University, 153003 Ivanovo, Russia
| | - Hajnalka Nádasi
- Otto von Guericke University, Inst. of Physics, Dept. Nonlinear Phenomena, Universitaetsplatz 2, 39106 Magdeburg, Germany.
| | - Torsten Trittel
- Otto von Guericke University, Inst. of Physics, Dept. Nonlinear Phenomena, Universitaetsplatz 2, 39106 Magdeburg, Germany.
| | - Ralf Stannarius
- Otto von Guericke University, Inst. of Physics, Dept. Nonlinear Phenomena, Universitaetsplatz 2, 39106 Magdeburg, Germany.
| | - Peter Veit
- Otto von Guericke University, Inst. of Physics, Dept. Semiconductor Physics, Universitaetsplatz 2, 39106 Magdeburg, Germany
| | - Alexey Eremin
- Otto von Guericke University, Inst. of Physics, Dept. Nonlinear Phenomena, Universitaetsplatz 2, 39106 Magdeburg, Germany.
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18
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Eremin A, Bulychev AA, Kluge C, Harbinson J, Foissner I. PH-dependent cell-cell interactions in the green alga Chara. Protoplasma 2019; 256:1737-1751. [PMID: 31367920 PMCID: PMC6820879 DOI: 10.1007/s00709-019-01392-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 04/29/2019] [Indexed: 06/10/2023]
Abstract
Characean internodal cells develop alternating patterns of acid and alkaline zones along their surface in order to facilitate uptake of carbon required for photosynthesis. In this study, we used a pH-indicating membrane dye, 4-heptadecylumbiliferone, to study the kinetics of alkaline band formation and decomposition. The differences in growth/decay kinetics suggested that growth occurred as an active, autocatalytic process, whereas decomposition was due to diffusion. We further investigated mutual interactions between internodal cells and found that their alignment parallel to each other induced matching of the pH banding patterns, which was mirrored by chloroplast activity. In non-aligned cells, the lowered photosynthetic activity was noted upon a rise of the external pH, suggesting that the matching of pH bands was due to a local elevation of membrane conductance by the high pH of the alkaline zones of neighboured cells. Finally, we show that the altered pH banding pattern caused the reorganization of the cortical cytoplasm. Complex plasma membrane elaborations (charasomes) were degraded via endocytosis, and mitochondria were moved away from the cortex when a previously acid region became alkaline and vice versa. Our data show that characean internodal cells react flexibly to environmental cues, including those originating from neighboured cells.
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Affiliation(s)
- Alexey Eremin
- Institute of Physics, Otto von Guericke University of Magdeburg, 39016, Magdeburg, Germany
| | - Alexander A Bulychev
- Department of Biophysics, Faculty of Biology, Moscow State University, Moscow, 119991, Russia
| | - Christopher Kluge
- Institute of Physics, Otto von Guericke University of Magdeburg, 39016, Magdeburg, Germany
| | - Jeremy Harbinson
- Department of Plant Sciences, University of Wageningen, 6708 PB, Wageningen, The Netherlands
| | - Ilse Foissner
- Department of Biosciences, University of Salzburg, 5020, Salzburg, Austria.
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19
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Klopp C, Trittel T, Eremin A, Harth K, Stannarius R, Park CS, Maclennan JE, Clark NA. Structure and dynamics of a two-dimensional colloid of liquid droplets. Soft Matter 2019; 15:8156-8163. [PMID: 31595938 DOI: 10.1039/c9sm01433k] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Droplet arrays in thin, freely suspended liquid-crystalline smectic A films can form two-dimensional (2D) colloids. The droplets interact repulsively, arranging locally in a more or less hexagonal arrangement with only short-range spatial and orientational correlations and local lattice cell parameters that depend on droplet size. In contrast to quasi-2D colloids described earlier, there is no 3D bulk liquid subphase that affects the hydrodynamics. Although the films are surrounded by air, the droplet dynamics are genuinely 2D, the mobility of each droplet in its six-neighbor cage being determined by the ratio of cage and droplet sizes, rather than by the droplet size as in quasi-2D colloids. These experimental observations are described well by Saffman's model of a diffusing particle in a finite 2D membrane. The experiments were performed in microgravity, on the International Space Station.
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Affiliation(s)
- Christoph Klopp
- Institute of Physics, Otto von Guericke University, Universitätsplatz 2, D-39106 Magdeburg, Germany.
| | - Torsten Trittel
- Institute of Physics, Otto von Guericke University, Universitätsplatz 2, D-39106 Magdeburg, Germany.
| | - Alexey Eremin
- Institute of Physics, Otto von Guericke University, Universitätsplatz 2, D-39106 Magdeburg, Germany.
| | - Kirsten Harth
- Institute of Physics, Otto von Guericke University, Universitätsplatz 2, D-39106 Magdeburg, Germany.
| | - Ralf Stannarius
- Institute of Physics, Otto von Guericke University, Universitätsplatz 2, D-39106 Magdeburg, Germany.
| | - Cheol S Park
- Soft Materials Research Center, Physics Department, University of Colorado, Boulder, CO 80309, USA
| | - Joseph E Maclennan
- Soft Materials Research Center, Physics Department, University of Colorado, Boulder, CO 80309, USA
| | - Noel A Clark
- Soft Materials Research Center, Physics Department, University of Colorado, Boulder, CO 80309, USA
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20
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Nádasi H, Corradi Á, Stannarius R, Koch K, Schmidt AM, Aya S, Araoka F, Eremin A. The role of structural anisotropy in the magnetooptical response of an organoferrogel with mobile magnetic nanoparticles. Soft Matter 2019; 15:3788-3795. [PMID: 30990220 DOI: 10.1039/c9sm00219g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigate the structure and the magnetooptical response of isotropic and anisotropic fibrillous organoferrogels with mobile magnetic nanoparticles (MNPs). We demonstrate that the presence of the gel network restricts the magnetooptical response of the ferrogel. Even though the ferrogel exhibits no magnetic hysteresis, an optical hysteresis has been found. This suggests that the magnetooptical response is primarily determined by the dynamics of self-assembly of the MNPs into shape-anisotropic agglomerates. Furthermore, we show that the optical anisotropy of the system can be fine-tuned by varying the concentration of the gelator and the MNPs, respectively. The optical response in structurally anisotropic gels becomes orientation-dependent, revealing an intricate interplay between the gel mesh and the MNPs.
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Affiliation(s)
- Hajnalka Nádasi
- Otto von Guericke University, Inst. of Physics, Dept. Nonlinear Phenomena, Universitaetsplatz 2, 39106 Magdeburg, Germany.
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21
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Alaasar M, Prehm M, Belau S, Sebastián N, Kurachkina M, Eremin A, Chen C, Liu F, Tschierske C. Polar Order, Mirror Symmetry Breaking, and Photoswitching of Chirality and Polarity in Functional Bent‐Core Mesogens. Chemistry 2019; 25:6362-6377. [DOI: 10.1002/chem.201806180] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/21/2019] [Indexed: 01/06/2023]
Affiliation(s)
- Mohamed Alaasar
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
- Department of Chemistry, Faculty of ScienceCairo University Giza Egypt
| | - Marko Prehm
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
| | - Sebastian Belau
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Nerea Sebastián
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Marharyta Kurachkina
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute of PhysicsOtto von Guericke University Magdeburg Magdeburg Germany
| | - Changlong Chen
- State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong University Xi'an 710049 P. R. China
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong University Xi'an 710049 P. R. China
| | - Carsten Tschierske
- Institute of ChemistryMartin Luther University Halle-Wittenberg Kurt Mothes Str. 2 06120 Halle (Saale) Germany
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22
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Eremin A, Nádasi H, Kurochkina M, Haba O, Yonetake K, Takezoe H. Light-Responsive Microstructures in Droplets of the Twist-Bend Nematic Phase. Langmuir 2018; 34:14519-14527. [PMID: 30253102 DOI: 10.1021/acs.langmuir.8b02823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the structure and optical manipulation of the director configurations in emulsions of liquid-crystalline droplets of a compound exhibiting the nematic (N) and the twist-bend nematic (NTB) phases. We demonstrate a decrease in the ratio of the bent elastic constant K33 to the splay constant K11 by nearly 2 orders of magnitude with decreasing temperature in the N phase. The director structures in liquid-crystal droplets doped with a photoswitchable surfactant without and under ultraviolet (UV) light are discussed in light of the strong elastic anisotropy of the investigated compound. We also compare our findings with the results obtained in doped nematic droplets of a conventional 4-cyano-4'-pentylbiphenyl (5CB) liquid crystal. The dynamics of droplets in the NTB phase by UV light irradiation are also studied using polarizing and confocal microscopies.
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Affiliation(s)
- Alexey Eremin
- Otto von Guericke University, Institute of Physics , 39016 Magdeburg , Germany
| | - Hajnalka Nádasi
- Otto von Guericke University, Institute of Physics , 39016 Magdeburg , Germany
| | | | - Osamu Haba
- Department of Organic Materials Science , Yamagata University , 4-3-16 Jonan , Yonezawa , Yamagata 992-8510 , Japan
| | - Koichiro Yonetake
- Department of Organic Materials Science , Yamagata University , 4-3-16 Jonan , Yonezawa , Yamagata 992-8510 , Japan
| | - Hideo Takezoe
- Toyota Physical and Chemical Research Institute , 41-1 Yokomichi , Nagakute , Aichi 480-1192 , Japan
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23
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Buluy O, Aryasova N, Tereshchenko O, Kurioz Y, Nazarenko V, Eremin A, Stannarius R, Klein S, Goldmann C, Davidson P, Dozov I, Reznikov Y. Optical and X-ray scattering studies of the electric field-induced orientational order in colloidal suspensions of pigment nanorods. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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24
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May K, Stannarius R, Kang K, Challa PK, Sprunt S, Jákli A, Klein S, Eremin A. Collective dynamics in dispersions of anisometric pigment particles. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.01.172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Lunchenkov N, Polushkin V, Ignatov E, Eremin A. 4.10-P21Immigrant men who have sex with men in Moscow, Russia. Common issues and implications for prevention of HIV among key-population groups. Eur J Public Health 2018. [DOI: 10.1093/eurpub/cky048.160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
| | - V Polushkin
- Sechenov First Moscow State Medical University, Russian Federation
| | - E Ignatov
- AIDS CENTER foundation, Russian Federation
- Plekhanov Russian University for Economics, Russian Federation
| | - A Eremin
- AIDS CENTER foundation, Russian Federation
- RUDN University, Russian Federation
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26
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Appel I, Nádasi H, Reitz C, Sebastián N, Hahn H, Eremin A, Stannarius R, Behrens SS. Doping of nematic cyanobiphenyl liquid crystals with mesogen-hybridized magnetic nanoparticles. Phys Chem Chem Phys 2017; 19:12127-12135. [PMID: 28447080 DOI: 10.1039/c7cp01438d] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Magnetic nanoparticles (MNPs) functionalized with (pro-)mesogenic ligands are implemented into a nematic liquid crystal (LC) and studied regarding both colloidal stability and magneto-optical behavior. In this study, the particle surface is specifically engineered to tune the MNP interactions with the LC host. For this purpose, four types of (pro-)mesogenic ligands (ML) are synthesized, which are composed of three structural parts, i.e., a rigid, LC motif (i.e., cyanobiphenyl) and a functional group for nanoparticle binding, both linked via a flexible spacer of different alkyl chain lengths. Electrostatically stabilized CoFe2O4 and γ-Fe2O3 nanoparticles with narrow size distribution and sizes below 3 nm are obtained via co-precipitation and subsequently functionalized to yield MNP@ML nanoparticles. Studies on the behaviour of the MNP@ML nanoparticles in the commercial LC host (i.e., 4-pentyl-4'-cyanobiphenyl (5CB)) in the bulk and in thin films in LC test cells, reveal the initial formation of some heterogeneities after transition from the isotropic to the nematic phase. Homogenous MNP@ML-5CB hybrids with long-term, colloidal stability, however, are obtained after magnetic separation of initially formed particle aggregates. In particular, MLs with carboxy groups and high structural flexibility (i.e., long linker lengths) are shown to be well suited to form stable MNP colloids, allowing for high MNP doping levels. As compared to undoped 5CB, the CoFe2O4@MLx-5CB hybrids show an increased sensitivity to the magnetic field, affecting the Fréedericksz transition. The strongest effect, however, is observed in magnetic and electric fields. The coupling of the ultrasmall, spherical MNPs with the LC director in the magnetic field suggests the formation of LC-induced, anisometric MNP clusters.
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Affiliation(s)
- Ingo Appel
- Institut für Katalyseforschung und -technologie, Karlsruher Institut für Technologie (KIT), Postfach 3640, 76021 Karlsruhe, Germany.
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27
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Nádasi H, Stannarius R, Eremin A, Ito A, Ishikawa K, Haba O, Yonetake K, Takezoe H, Araoka F. Photomanipulation of the anchoring strength using a spontaneously adsorbed layer of azo dendrimers. Phys Chem Chem Phys 2017; 19:7597-7606. [PMID: 28252118 DOI: 10.1039/c6cp08461c] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We systematically studied the photoinduced anchoring transition in a nematic liquid crystal containing azo dendrimers. Because the azo dendrimers in the trans-isomer state were spontaneously adsorbed at substrate surfaces, which was confirmed by optical second-harmonic generation (SHG), a homeotropic orientation was established at the first stage. Ultraviolet (UV) light irradiation triggered a transition into a planar state which was accompanied by a suppression of the SH generation. The monotonic decrease of the effective scalar order parameter with increasing UV light intensity was determined by polarized attenuated total reflection infrared (ATR-IR) spectroscopy. The variation of anchoring strength and extrapolation length was evaluated by observing the Fréedericksz transition as a function of UV light intensity at a certain visible (VIS) light intensity. Such a photoinduced variation can be interpreted as a variation of the anchoring strength depending on the trans/cis ratio at the surfaces based on a modified Rapini-Papoular model. Thus, this system provides the opportunity for a controlled change in the anchoring strength.
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Affiliation(s)
- Hajnalka Nádasi
- Otto-von-Guericke-Universität Magdeburg, Department of Nonlinear Phenomena, 39016 Magdeburg, Germany.
| | - Ralf Stannarius
- Otto-von-Guericke-Universität Magdeburg, Department of Nonlinear Phenomena, 39016 Magdeburg, Germany.
| | - Alexey Eremin
- Otto-von-Guericke-Universität Magdeburg, Department of Nonlinear Phenomena, 39016 Magdeburg, Germany.
| | - Atsuki Ito
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan and RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| | - Ken Ishikawa
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan
| | - Osamu Haba
- Department of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Koichiro Yonetake
- Department of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan
| | - Hideo Takezoe
- Toyota Physical and Chemical Research Institute, 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
| | - Fumito Araoka
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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28
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Sebastián N, Belau S, Eremin A, Alaasar M, Prehm M, Tschierske C. Emergence of polar order and tilt in terephthalate based bent-core liquid crystals. Phys Chem Chem Phys 2017; 19:5895-5905. [DOI: 10.1039/c6cp08145b] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The shown compound forms ferroelectric domains in a SmA phase, which adopt antipolar correlations before condensing into a weakly tilted antiferroelectric smectic phase.
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Affiliation(s)
- Nerea Sebastián
- Department of Nonlinear Phenomena
- Institute for Experimental Physics
- Otto von Guericke University Magdeburg
- Magdeburg
- Germany
| | - Sebastian Belau
- Department of Nonlinear Phenomena
- Institute for Experimental Physics
- Otto von Guericke University Magdeburg
- Magdeburg
- Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena
- Institute for Experimental Physics
- Otto von Guericke University Magdeburg
- Magdeburg
- Germany
| | - Mohamed Alaasar
- Institute of Chemistry
- Organic Chemistry
- Martin Luther University Halle-Wittenberg
- 06120 Halle/Saale
- Germany
| | - Marko Prehm
- Institute of Chemistry
- Organic Chemistry
- Martin Luther University Halle-Wittenberg
- 06120 Halle/Saale
- Germany
| | - Carsten Tschierske
- Institute of Chemistry
- Organic Chemistry
- Martin Luther University Halle-Wittenberg
- 06120 Halle/Saale
- Germany
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29
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Salili SM, Ostapenko T, Kress O, Bailey C, Weissflog W, Harth K, Eremin A, Stannarius R, Jákli A. Rupture and recoil of bent-core liquid crystal filaments. Soft Matter 2016; 12:4725-4730. [PMID: 27140824 DOI: 10.1039/c6sm00290k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The recoil process of free-standing liquid crystal filaments is investigated experimentally and theoretically. We focus on two aspects, the contraction speed of the filament and a spontaneously formed undulation instability. At the moment of rupture, the filaments buckle similarly to the classical Euler buckling of elastic rods. The tip velocity decays with decreasing filament length. The wavelength of buckling affinely decreases with the retracting filament tip. The energy gain related to the decrease of the total length and surface area of the filaments is mainly dissipated by layer rearrangements during thickening of the fibre. A flow back into the meniscus is relevant only in the final stage of the recoil process. We introduce a model for the quantitative description of the filament retraction speed. The dynamics of this recoil behaviour may find relevance as a model for biology-related filaments.
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Affiliation(s)
- S M Salili
- Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
| | - T Ostapenko
- Institute of Experimental Physics, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany.
| | - O Kress
- Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
| | - C Bailey
- Leidos, 3745 Pentagon Blvd., Beavercreek, OH 45431, USA
| | - W Weissflog
- Martin Luther University Halle-Wittenberg, Department of Chemistry, Physical Chemistry, von-Danckelmann-Platz 4, 06120 Halle, Germany
| | - K Harth
- Institute of Experimental Physics, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany.
| | - A Eremin
- Institute of Experimental Physics, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany.
| | - R Stannarius
- Institute of Experimental Physics, Otto von Guericke University, Universitätsplatz 2, 39106 Magdeburg, Germany.
| | - A Jákli
- Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
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May K, Eremin A, Stannarius R, Peroukidis SD, Klapp SHL, Klein S. Colloidal Suspensions of Rodlike Nanocrystals and Magnetic Spheres under an External Magnetic Stimulus: Experiment and Molecular Dynamics Simulation. Langmuir 2016; 32:5085-5093. [PMID: 27119202 DOI: 10.1021/acs.langmuir.6b00739] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using experiments and molecular dynamics simulations, we explore magnetic field-induced phase transformations in suspensions of nonmagnetic rodlike and magnetic sphere-shaped particles. We experimentally demonstrate that an external uniform magnetic field causes the formation of small, stable clusters of magnetic particles that, in turn, induce and control the orientational order of the nonmagnetic subphase. Optical birefringence was studied as a function of the magnetic field and the volume fractions of each particle type. Steric transfer of the orientational order was investigated by molecular dynamics (MD) simulations; the results are in qualitative agreement with the experimental observations. By reproducing the general experimental trends, the MD simulation offers a cohesive bottom-up interpretation of the physical behavior of such systems, and it can also be regarded as a guide for further experimental research.
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Affiliation(s)
- Kathrin May
- Otto-von-Guericke Universität Magdeburg , Universitätplatz 2, 39106 Magdeburg, Germany
| | - Alexey Eremin
- Otto-von-Guericke Universität Magdeburg , Universitätplatz 2, 39106 Magdeburg, Germany
| | - Ralf Stannarius
- Otto-von-Guericke Universität Magdeburg , Universitätplatz 2, 39106 Magdeburg, Germany
| | - Stavros D Peroukidis
- Institute of Theoretical Physics, Technical University Berlin , Secr. EW 7-1 Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - Sabine H L Klapp
- Institute of Theoretical Physics, Technical University Berlin , Secr. EW 7-1 Hardenbergstrasse 36, D-10623 Berlin, Germany
| | - Susanne Klein
- HP Laboratories , Long Down Avenue, Stoke Gifford, Bristol BS34 8QZ, U.K
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31
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Westphal E, Gallardo H, Caramori GF, Sebastián N, Tamba MG, Eremin A, Kawauchi S, Prehm M, Tschierske C. Polar Order and Symmetry Breaking at the Boundary between Bent-Core and Rodlike Molecular Forms: When 4-Cyanoresorcinol Meets the Carbosilane End Group. Chemistry 2016; 22:8181-97. [DOI: 10.1002/chem.201503901] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Eduard Westphal
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2; 06120 Halle/Saale Germany
- Department of Chemistry; Federal University of Santa Catarina; 88040-900 Florianópolis Brazil
| | - Hugo Gallardo
- Department of Chemistry; Federal University of Santa Catarina; 88040-900 Florianópolis Brazil
| | | | - Nerea Sebastián
- Department of Nonlinear Phenomena, Institute for Experimental Physics; Otto von Guericke University Magdeburg, Universitätsplatz 2; 39106 Magdeburg Germany
| | - Maria-Gabriela Tamba
- Department of Nonlinear Phenomena, Institute for Experimental Physics; Otto von Guericke University Magdeburg, Universitätsplatz 2; 39106 Magdeburg Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Experimental Physics; Otto von Guericke University Magdeburg, Universitätsplatz 2; 39106 Magdeburg Germany
| | - Susumu Kawauchi
- Department of Organic & Polymeric Materials; Tokyo Institute of Technology, O-okayama, Meguro-ku; Tokyo 152-8552 Japan
| | - Marko Prehm
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2; 06120 Halle/Saale Germany
| | - Carsten Tschierske
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2; 06120 Halle/Saale Germany
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32
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Kredentser S, Eremin A, Davidson P, Reshetnyak V, Stannarius R, Reznikov Y. Light-induced Soret effect and adsorption of nanocrystals in organic solvents. Eur Phys J E Soft Matter 2016; 39:38. [PMID: 27021655 DOI: 10.1140/epje/i2016-16038-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 01/21/2016] [Indexed: 06/05/2023]
Abstract
A light-induced Soret effect accompanied by photoinduced adsorption of pigment nanoparticles is described in organic solvents. We report an unexpected inversion of the nanoparticle flux which is directed along the temperarture gradient at short exposures to the light and switches against the gradient at longer exposures. This change of flux direction is due to light-induced adsorption of the nanocrystals onto the substrates of the cell.
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Affiliation(s)
- S Kredentser
- Institute of Physics of National Academy of Sciences of Ukraine, Pr. Nauky 46, 03028, Kyiv, Ukraine.
| | - A Eremin
- Otto-von-Guericke-Universität Magdeburg, 4120, Magdeburg, Germany
| | - P Davidson
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, 91405, Orsay, France
| | - V Reshetnyak
- Taras Shevchenko National University of Kyiv, 01601, Kyiv, Ukraine
| | - R Stannarius
- Otto-von-Guericke-Universität Magdeburg, 4120, Magdeburg, Germany
| | - Yu Reznikov
- Institute of Physics of National Academy of Sciences of Ukraine, Pr. Nauky 46, 03028, Kyiv, Ukraine
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33
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Eremin A, Geng Y, Stannarius R, Ostapenko T, Challa PK, Gleeson JT, Jákli A, Klein S. Correction: Peculiarities of the magneto-optical response in dispersions of anisometric pigment nano-particles. RSC Adv 2016. [DOI: 10.1039/c6ra90089e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Correction for ‘Peculiarities of the magneto-optical response in dispersions of anisometric pigment nano-particles’ by A. Eremin et al., RSC Adv., 2016, 6, 80666–80669.
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Affiliation(s)
- A. Eremin
- Otto-von-Guericke-Universität Magdeburg
- FNW/IEP/ANP
- 39016 Magdeburg
- Germany
| | - Y. Geng
- Otto-von-Guericke-Universität Magdeburg
- FNW/IEP/ANP
- 39016 Magdeburg
- Germany
| | - R. Stannarius
- Otto-von-Guericke-Universität Magdeburg
- FNW/IEP/ANP
- 39016 Magdeburg
- Germany
| | - T. Ostapenko
- Max Planck Institute for Dynamics and Self-Organization (MPIDS)
- 37077 Göttingen
- Germany
| | - P. K. Challa
- Department of Physics
- Kent State University
- Kent
- USA
| | | | - A. Jákli
- Liquid Crystal Institute
- Kent State University
- Kent
- USA
| | - S. Klein
- HP Laboratories
- Bristol BS34 8QZ
- UK
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34
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Sebastián N, Tamba MG, Stannarius R, de la Fuente MR, Salamonczyk M, Cukrov G, Gleeson J, Sprunt S, Jákli A, Welch C, Ahmed Z, Mehl GH, Eremin A. Mesophase structure and behaviour in bulk and restricted geometry of a dimeric compound exhibiting a nematic–nematic transition. Phys Chem Chem Phys 2016; 18:19299-308. [DOI: 10.1039/c6cp03899a] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate a liquid crystal system exhibiting a variety of modulated structures on different length-scales: from helicoidal nematic to modulated smectic.
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35
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Eremin A, Geng Y, Stannarius R, Ostapenko T, Challa PK, Gleeson JT, Jákli A, Klein S. Peculiarities of the magneto-optical response in dispersions of anisometric pigment nano-particles. RSC Adv 2016. [DOI: 10.1039/c6ra12020b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We demonstrate an unusually strong magneto-optical response of elongated plate-shaped pigment particles in magnetic fields ranging from 0 to 25 T.
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Affiliation(s)
- A. Eremin
- Otto-von-Guericke-Universität Magdeburg
- FNW/IEP/ANP
- 39016 Magdeburg
- Germany
| | - Y. Geng
- Otto-von-Guericke-Universität Magdeburg
- FNW/IEP/ANP
- 39016 Magdeburg
- Germany
| | - R. Stannarius
- Otto-von-Guericke-Universität Magdeburg
- FNW/IEP/ANP
- 39016 Magdeburg
- Germany
| | - T. Ostapenko
- Max Planck Institute for Dynamics and Self-Organization (MPIDS)
- 37077 Göttingen
- Germany
| | - P. K. Challa
- Department of Physics
- Kent State University
- Kent
- USA
| | | | - A. Jákli
- Liquid Crystal Institute
- Kent State University
- Kent
- USA
| | - S. Klein
- HP Laboratories
- Bristol BS34 8QZ
- UK
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36
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Alaasar M, Prehm M, Tamba MG, Sebastián N, Eremin A, Tschierske C. Development of Polar Order in the Liquid Crystal Phases of a 4-Cyanoresorcinol-Based Bent-Core Mesogen with Fluorinated Azobenzene Wings. Chemphyschem 2015; 17:278-87. [DOI: 10.1002/cphc.201500891] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Indexed: 01/17/2023]
Affiliation(s)
- Mohamed Alaasar
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
- Department of Chemistry; Faculty of Science; Cairo University; Giza Egypt
| | - Marko Prehm
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
| | - Maria-Gabriela Tamba
- Institute for Experimental Physics; Otto-von-Guericke University Magdeburg; Universitätsplatz 2 39106 Magdeburg Germany
| | - Nerea Sebastián
- Institute for Experimental Physics; Otto-von-Guericke University Magdeburg; Universitätsplatz 2 39106 Magdeburg Germany
| | - Alexey Eremin
- Institute for Experimental Physics; Otto-von-Guericke University Magdeburg; Universitätsplatz 2 39106 Magdeburg Germany
| | - Carsten Tschierske
- Institute of Chemistry, Organic Chemistry; Martin Luther University Halle-Wittenberg; Kurt-Mothes Str. 2 06120 Halle/Saale Germany
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37
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Chattham N, Tamba MG, Stannarius R, Westphal E, Gallardo H, Prehm M, Tschierske C, Takezoe H, Eremin A. Leaning-type polar smectic-C phase in a freely suspended bent-core liquid crystal film. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 91:030502. [PMID: 25871036 DOI: 10.1103/physreve.91.030502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Indexed: 06/04/2023]
Abstract
A rich variety of responsive behavior occurs in complex structured fluids due to their lower symmetries. On the other hand, fluid disorder tends to increase the symmetry of liquid crystal mesophases. Here, we report direct evidence for the existence of a mesophase with CS symmetry. The observations are based on optical studies of director inversion walls in freely suspended films in electric fields under obliquely incident light. This phase is distinguished by the polarization lying in the molecular tilt plane in freely suspended films. Such a low-symmetry polar fluid phase has been long predicted to occur in bent-core liquid crystals. The stability of this phase is attributed to the bent shape of the mesogens and dominating dispersion interactions.
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Affiliation(s)
- Nattaporn Chattham
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany
- Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Maria-Gabriela Tamba
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Ralf Stannarius
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Eduard Westphal
- Institute of Chemistry, Organic Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120 Halle, Germany
- Department of Chemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, Brazil
| | - Hugo Gallardo
- Department of Chemistry, Federal University of Santa Catarina, 88040-900 Florianópolis, Brazil
| | - Marko Prehm
- Institute of Chemistry, Organic Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120 Halle, Germany
| | - Carsten Tschierske
- Institute of Chemistry, Organic Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Strasse 2, 06120 Halle, Germany
| | - Hideo Takezoe
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany
| | - Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, Magdeburg, Germany
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38
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Abstract
We demonstrate the nanostructure and filament formation of a novel liquid crystal phase of a dimeric mesogen below the twist–bend nematic phase.
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Affiliation(s)
- M. G. Tamba
- Department of Nonlinear Phenomena
- Institute for Experimental Physics
- Otto von Guericke University Magdeburg
- Magdeburg
- Germany
| | - S. M. Salili
- Liquid Crystal Institute
- Kent State University
- Kent
- USA
| | - C. Zhang
- Liquid Crystal Institute
- Kent State University
- Kent
- USA
| | - A. Jákli
- Liquid Crystal Institute
- Kent State University
- Kent
- USA
| | - G. H. Mehl
- Department of Chemistry
- University of Hull
- Hull HU6 7RX
- UK
| | - R. Stannarius
- Department of Nonlinear Phenomena
- Institute for Experimental Physics
- Otto von Guericke University Magdeburg
- Magdeburg
- Germany
| | - A. Eremin
- Department of Nonlinear Phenomena
- Institute for Experimental Physics
- Otto von Guericke University Magdeburg
- Magdeburg
- Germany
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39
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Hirankittiwong P, Chattham N, Limtrakul J, Haba O, Yonetake K, Eremin A, Stannarius R, Takezoe H. Optical manipulation of the nematic director field around microspheres covered with an azo-dendrimer monolayer. Opt Express 2014; 22:20087-20093. [PMID: 25321218 DOI: 10.1364/oe.22.020087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report here the optical manipulation of the director and topological defect structures of nematic liquid crystals around a silica microparticle with azobenzene-containing dendrimers (azo-dendrimers) on its surface. We successfully demonstrate the successive switching processes from hedgehog, to boojum, and further to Saturn ring configurations by ultraviolet (UV) light irradiation and termination. The switching time between these defect structures depends on the UV light intensity and attains about 50 ms. Since the pretreatment of microparticles is not necessary and the surface modification is spontaneously performed just by dissolving the azo-dendrimers in liquid crystals, this dendrimer supplies us with a variety of possible applications.
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40
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May K, Stannarius R, Klein S, Eremin A. Electric-field-induced phase separation and homogenization dynamics in colloidal suspensions of dichroic rod-shaped pigment particles. Langmuir 2014; 30:7070-7076. [PMID: 24866927 DOI: 10.1021/la501120k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report a reversible phase separation phenomenon in nonpolar colloidal suspensions of rod-shaped dichroic pigment particles in an electric field. The voltage-frequency phase diagram features a variety of phases with different morphologies. Single static particle-rich islands, chains of islands, and dynamic patterns were found in this system. We demonstrate that those patterns exhibit complex relaxation dynamics toward the homogeneous field-free state once the external field is removed.
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Affiliation(s)
- Kathrin May
- Otto von Guericke University , Institute for Experimental Physics, Department for Nonlinear Phenomena, 39106 Magdeburg, Germany
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41
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Shanker G, Prehm M, Nagaraj M, Vij JK, Weyland M, Eremin A, Tschierske C. Inside Cover: 1,2,4-Oxadiazole-Based Bent-Core Liquid Crystals with Cybotactic Nematic Phases (ChemPhysChem 7/2014). Chemphyschem 2014. [DOI: 10.1002/cphc.201490031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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42
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Abstract
We prepared electrospun polylactic acid (PLA) fiber mats containing anisometric pigment nanoparticles and demonstrate their converse piezoelectric behavior.
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Affiliation(s)
- Kathrin May
- Otto-von-Guericke-Universität Magdeburg
- 39016 Magdeburg, Germany
| | - Alexey Eremin
- Otto-von-Guericke-Universität Magdeburg
- 39016 Magdeburg, Germany
| | - Ralf Stannarius
- Otto-von-Guericke-Universität Magdeburg
- 39016 Magdeburg, Germany
| | | | - Kristiaan Neyts
- Liquid Crystals and Photonics Group
- ELIS Department
- Ghent University
- 9000 Ghent, Belgium
| | - John Harden
- Liquid Crystal Institute
- Kent State University
- Kent, USA
| | - Antal Jákli
- Liquid Crystal Institute
- Kent State University
- Kent, USA
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43
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Eremin A, Kornek U, Stannarius R, Weissflog W, Nádasi H, Araoka F, Takezoe H. Labyrinthine instability in freely suspended films of a polarization-modulated smectic phase. Phys Rev E Stat Nonlin Soft Matter Phys 2013; 88:062512. [PMID: 24483473 DOI: 10.1103/physreve.88.062512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Indexed: 06/03/2023]
Abstract
We report on fingering and labyrinthine instabilities of the layer dislocation lines in freely suspended polar liquid-crystalline films. These polar fingerlike and labyrinth structures reversibly form upon a transition into a modulated phase. External electric fields of several kV/m applied in the film plane can reversibly influence the formation of the finger textures. We show that the labyrinthine pattern is intrinsically related to regular splay deformations of the polarization.
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Affiliation(s)
- Alexey Eremin
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, PO box 4120, 39106 Magdeburg, Germany
| | - Ulrike Kornek
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, PO box 4120, 39106 Magdeburg, Germany
| | - Ralf Stannarius
- Department of Nonlinear Phenomena, Institute for Experimental Physics, Otto von Guericke University Magdeburg, PO box 4120, 39106 Magdeburg, Germany
| | - Wolfgang Weissflog
- Institute for Physical Chemistry, Martin Luther University Halle Wittenberg, von Danckelmann Platz 4, 06120 Halle (Saale), Germany
| | - Hajnalka Nádasi
- Institute for Physical Chemistry, Martin Luther University Halle Wittenberg, von Danckelmann Platz 4, 06120 Halle (Saale), Germany
| | - Fumito Araoka
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Hideo Takezoe
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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44
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Eremin A, Bulychev A, Hauser MJB. Cyclosis-mediated transfer of H2O 2 elicited by localized illumination of Chara cells and its relevance to the formation of pH bands. Protoplasma 2013; 250:1339-49. [PMID: 23760663 DOI: 10.1007/s00709-013-0517-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 05/27/2013] [Indexed: 05/09/2023]
Abstract
Cytoplasmic streaming occurs in most plant cells and is vitally important for large cells as a means of long-distance intracellular transport of metabolites and messengers. In internodal cells of characean algae, cyclosis participates in formation of light-dependent patterns of surface pH and photosynthetic activity, but lateral transport of regulatory metabolites has not been visualized yet. Hydrogen peroxide, being a signaling molecule and a stress factor, is known to accumulate under excessive irradiance. This study was aimed to examine whether H2O2 produced in chloroplasts under high light conditions is released into streaming fluid and transported downstream by cytoplasmic flow. To this end, internodes of Chara corallina were loaded with the fluorogenic probe dihydrodichlorofluorescein diacetate and illuminated locally by a narrow light beam through a thin optic fiber. Fluorescence of dihydrodichlorofluorescein (DCF), produced upon oxidation of the probe by H2O2, was measured within and around the illuminated cell region. In cells exhibiting active streaming, H2O2 first accumulated in the illuminated region and then entered into the streaming cytoplasm, giving rise to the expansion of DCF fluorescence downstream of the illuminated area. Inhibition of cyclosis by cytochalasin B prevented the spreading of DCF fluorescence along the internode. The results suggest that H2O2 released from chloroplasts under high light is transported along the cell with the cytoplasmic flow. It is proposed that the shift of cytoplasmic redox poise and light-induced elevation of cytoplasmic pH facilitate the opening of H(+)/OH(-)-permeable channels in the plasma membrane.
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Affiliation(s)
- Alexey Eremin
- Institute of Experimental Physics, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39016, Magdeburg, Germany
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45
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Aghsaee M, Drakon A, Eremin A, Dürrstein SH, Böhm H, Somnitz H, Fikri M, Schulz C. Experimental investigation and modeling of the kinetics of CCl4 pyrolysis behind reflected shock waves using high-repetition-rate time-of-flight mass spectrometry. Phys Chem Chem Phys 2013; 15:2821-8. [PMID: 23338791 DOI: 10.1039/c2cp42574b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The pyrolysis kinetics of CCl(4) behind reflected shock waves was studied with high-repetition-rate time-of-flight mass spectrometry. For modeling, quantum mechanical calculations were performed to evaluate the dissociation energies of CCl bonds for the different CCl(x) (x = 1 to 4) radicals. Good agreement with the JANAF thermochemical table was found. With the reaction mechanism developed for CCl(4) decomposition satisfactory agreement with experimental results was obtained. The investigations show the importance of C(2)Cl(2) formation for understanding the processes of carbon cluster growth leading to carbonaceous particle formation.
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Affiliation(s)
- M Aghsaee
- IVG, Institute for Combustion of Gasdynamics, University of Duisburg-Essen, Duisburg, Germany
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46
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Eremin A, Floegel M, Kornek U, Stern S, Stannarius R, Nádasi H, Weissflog W, Zhu C, Shen Y, Park CS, Maclennan J, Clark N. Transitions between paraelectric and ferroelectric phases of bent-core smectic liquid crystals in the bulk and in thin freely suspended films. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:051701. [PMID: 23214799 DOI: 10.1103/physreve.86.051701] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Indexed: 06/01/2023]
Abstract
We report on the contrasting phase behavior of a bent-core liquid crystal with a large opening angle between the mesogenic units in the bulk and in freely suspended films. Second-harmonic generation experiments and direct observation of director inversion walls in films in an applied electric field reveal that the nonpolar smectic C phase observed in bulk samples becomes a ferroelectric "banana" phase in films, showing that a mesogen with a small steric moment can give a phase with polar order in freely suspended films even when the corresponding bulk phase is paraelectric.
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Affiliation(s)
- Alexey Eremin
- Otto-von-Guericke-Universität Magdeburg, Institute for Experimental Physics, ANP, D-39016 Magdeburg, Germany
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47
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Morys M, Trittel T, Eremin A, Murphy P, Stannarius R. Tension of freely suspended fluid filaments. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 86:040501. [PMID: 23214519 DOI: 10.1103/physreve.86.040501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Indexed: 06/01/2023]
Abstract
Stable fluid filaments with diameters of several micrometers and slenderness ratios well above 1000 are unique objects formed by some liquid crystalline phases of bent-core mesogens. We present a technique to determine filament tensions from their deflection under defined loads. A strong temperature dependence is observed, with a minimum near the clearing temperature. Both the nonlinear relation between filament tension and diameter and the substantial increase of the tension with lower temperatures indicate contributions of volume terms, in addition to surface capillary forces. We discuss a model that relates these bulk terms to elastic forces, originating from the undulated smectic layer structure. This model can explain the origin of the filament stability.
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Affiliation(s)
- M Morys
- Otto von Guericke University Magdeburg, Institute of Experimental Physics, Universitätsplatz 2, D-39106 Magdeburg, Germany
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48
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Eremin A, Kornek U, Stern S, Stannarius R, Araoka F, Takezoe H, Nádasi H, Weissflog W, Jákli A. Pattern-stabilized decorated polar liquid-crystal fibers. Phys Rev Lett 2012; 109:017801. [PMID: 23031131 DOI: 10.1103/physrevlett.109.017801] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Indexed: 06/01/2023]
Abstract
Geometric frustration gives rise to new fundamental phenomena and is known to yield the formation of exotic states of matter, such as incommensurate crystals, modulated liquid-crystalline phases, and phases stabilized by defects. In this Letter, we present a detailed study of polar structure of freely suspended fluid filaments in a polarization modulated liquid-crystal phase. We show that a periodic pattern of polarization-splay stripes separated by defect boundaries and decorating smectic layers can stabilize the structure of fluid fibers against the Rayleigh-Plateau instability. The instability is suppressed by the resistance of the defect structure to a radial compression of the cylindrical fibers. Our results provide direct experimental observation of a link between the stability of the liquid fibers, internal polar order, and geometrical constraints. They open a new perspective on a wide range of fluid polar fiber materials.
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Affiliation(s)
- Alexey Eremin
- Otto-von-Guericke Universität Magdeburg, Institute for Experimental Physics, ANP, 39016 Magdeburg, Germany.
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Eremin A, Baumgarten S, Harth K, Stannarius R, Nguyen ZH, Goldfain A, Park CS, Maclennan JE, Glaser MA, Clark NA. Two-dimensional microrheology of freely suspended liquid crystal films. Phys Rev Lett 2011; 107:268301. [PMID: 22243186 DOI: 10.1103/physrevlett.107.268301] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 08/21/2011] [Indexed: 05/31/2023]
Abstract
Smectic liquid crystals form freely-suspended, fluid films of highly uniform structure and thickness, making them ideal systems for studies of hydrodynamics in two dimensions. We have measured particle mobility and shear viscosity by direct observation of the gravitational drift of silica spheres and smectic islands included in these fluid membranes. In thick films, we observe a hydrodynamic regime dominated by lateral confinement effects, with the mobility of the inclusion determined predominantly by coupling of the fluid flow to the fixed boundaries of the film. In thin films, the mobility of inclusions is governed primarily by coupling of the fluid to the surrounding air, as predicted by Saffman-Delbrück theory.
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Affiliation(s)
- A Eremin
- Otto-von-Guericke Universität Magdeburg, Institute for Experimental Physics, D-39016 Magdeburg, Germany
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Abstract
Abstract
The formation of condensed particles in atmospheric ethylene-oxygen and acetylene-air premixed flames catalyzed by the vapours of Fe(CO)5 and Mo(CO)6 was studied in the wide range of C/O ratio. Laser scattering and extinction measurements were carried out in a wide frame of flame conditions. The structure and the morphology of formed particles were analyzed using electron microscope. Different formation of the particles takes place due to the fuels and also to the catalyst. In the C2H2/air flame catalyzed with Mo(CO)6, particle formation starts at about threshold of soot formation (C/O ~ 0.6), while in the flames doped with Fe(CO)5, particle formation starts already in the lean range of both premixed flames investigated here.
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Affiliation(s)
| | | | | | - H.Gg. Wagner
- University Goettingen, Institute for Physical Chemistry, Göttingen, Deutschland
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