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Andreou C, Frielinghaus H, Rauh J, Mußmann M, Vauth S, Braun P, Leicht G, Mulert C. Theta and high-beta networks for feedback processing: a simultaneous EEG-fMRI study in healthy male subjects. Transl Psychiatry 2017; 7:e1016. [PMID: 28140398 PMCID: PMC5299393 DOI: 10.1038/tp.2016.287] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/29/2016] [Accepted: 11/30/2016] [Indexed: 12/29/2022] Open
Abstract
The reward system is important in assessing outcomes to guide behavior. To achieve these purposes, its core components interact with several brain areas involved in cognitive and emotional processing. A key mechanism suggested to subserve these interactions is oscillatory activity, with a prominent role of theta and high-beta oscillations. The present study used single-trial coupling of simultaneously recorded electroencephalography and functional magnetic resonance imaging data to investigate networks associated with oscillatory responses to feedback during a two-choice gambling task in healthy male participants (n=19). Differential associations of theta and high-beta oscillations with non-overlapping brain networks were observed: Increase of high-beta power in response to positive feedback was associated with activations in a largely subcortical network encompassing core areas of the reward network. In contrast, theta-band power increase upon loss was associated with activations in a frontoparietal network that included the anterior cingulate cortex. Trait impulsivity correlated significantly with activations in areas of the theta-associated network. Our results suggest that positive and negative feedback is processed by separate brain networks associated with different cognitive functions. Communication within these networks is mediated by oscillations of different frequency, possibly reflecting different modes of dopaminergic signaling.
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Affiliation(s)
- C Andreou
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Center for Gender Research and Early Detection, University of Basel Psychiatric Clinics, Basel, Switzerland
| | - H Frielinghaus
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - J Rauh
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Mußmann
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - S Vauth
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - P Braun
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - G Leicht
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - C Mulert
- Psychiatry Neuroimaging Branch, Department of Psychiatry and Psychotherapy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Mangiapia G, Gvaramia M, Kuhrts L, Teixeira J, Koutsioubas A, Soltwedel O, Frielinghaus H. Effect of benzocaine and propranolol on phospholipid-based bilayers. Phys Chem Chem Phys 2017; 19:32057-32071. [DOI: 10.1039/c7cp06077g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Drug/bilayer interactions are fundamental in determining the action mechanism of active ingredients. Neutron techniques represent unique tools for having a clear comprehension of such interactions.
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Affiliation(s)
- G. Mangiapia
- Forschungszentrum Jülich GmbH
- Jülich Centre for Neutron Science Außenstelle am Heinz Maier-Leibnitz Zentrum
- D-85747 Garching
- Germany
| | - M. Gvaramia
- Forschungszentrum Jülich GmbH
- Jülich Centre for Neutron Science Außenstelle am Heinz Maier-Leibnitz Zentrum
- D-85747 Garching
- Germany
- Ivane Javakhishvili Tbilisi State University
| | - L. Kuhrts
- Forschungszentrum Jülich GmbH
- Jülich Centre for Neutron Science Außenstelle am Heinz Maier-Leibnitz Zentrum
- D-85747 Garching
- Germany
| | - J. Teixeira
- Laboratoire Léon Brillouin (CEA-CNRS)
- CEA-Saclay
- F-91191 Gif-sur-Yvette CEDEX
- France
| | - A. Koutsioubas
- Forschungszentrum Jülich GmbH
- Jülich Centre for Neutron Science Außenstelle am Heinz Maier-Leibnitz Zentrum
- D-85747 Garching
- Germany
| | - O. Soltwedel
- Heinz Maier-Leibnitz Zentrum
- Technische Universität München
- D-85747 Garching
- Germany
| | - H. Frielinghaus
- Forschungszentrum Jülich GmbH
- Jülich Centre for Neutron Science Außenstelle am Heinz Maier-Leibnitz Zentrum
- D-85747 Garching
- Germany
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3
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Campanella A, Brás A, Raftopoulos K, Papadakis C, Vassiliadou O, Kyritsis A, Appavou M, Müller-Buschbaum P, Frielinghaus H. Dielectric relaxations of nanocomposites composed of HEUR polymers and magnetite nanoparticles. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.04.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Campanella A, Holderer O, Raftopoulos KN, Papadakis CM, Staropoli MP, Appavou MS, Müller-Buschbaum P, Frielinghaus H. Multi-stage freezing of HEUR polymer networks with magnetite nanoparticles. Soft Matter 2016; 12:3214-3225. [PMID: 26924466 DOI: 10.1039/c6sm00074f] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We observe a change in the segmental dynamics of hydrogels based on hydrophobically modified ethoxylated urethanes (HEUR) when hydrophobic magnetite nanoparticles (MNPs) are embedded in the hydrogels. The dynamics of the nanocomposite hydrogels is investigated using dielectric relaxation spectroscopy (DRS) and neutron spin echo (NSE) spectroscopy. The magnetic nanoparticles within the hydrophobic domains of the HEUR polymer network increase the size of these domains and their distance. The size increase leads to a dilution of the polymers close to the hydrophobic domain, allowing higher mobility of the smallest polymer blobs close to the "center". This is reflected in the decrease of the activation energy of the β-process detected in the DRS data. The increase in distance leads to an increase of the size of the largest hydrophilic polymer blobs. Therefore, the segmental dynamics of the largest blobs is slowed down. At short time scales, i.e. 10(-9) s < τ < 10(-3) s, the suppression of the segmental dynamics is reflected in the α-relaxation processes detected in the DRS data and in the decrease of the relaxation rate Γ of the segmental motion in the NSE data with increasing concentration of magnetic nanoparticles. The stepwise (multi-stage) freezing of the small blobs is only visible for the pure hydrogel at low temperatures. On the other hand, the glass transition temperature (Tg) decreases upon increasing the MNP loading, indicating an acceleration of the segmental dynamics at long time scales (τ∼ 100 s). Therefore, it would be possible to tune the Tg of the hydrogels by varying the MNP concentration. The contribution of the static inhomogeneities to the total scattering function Sst(q) is extracted from the NSE data, revealing a more ordered gel structure than the one giving rise to the total scattering function S(q), with a relaxed correlation length ξNSE = (43 ± 5) Å which is larger than the fluctuating correlation length from a static investigation ξSANS = (17.2 ± 0.3) Å.
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Affiliation(s)
- A Campanella
- JCNS@FRMII, Lichtenbergstraße 1, 85747 Garching, Germany.
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5
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Holderer O, Lipfert F, Frielinghaus H, Ohl M, Richter D. Interfaces modify the undulation spectrum of bicontinuous microemulsions. EPJ Web of Conferences 2015. [DOI: 10.1051/epjconf/20158302006] [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: 11/14/2022] Open
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Lipfert F, Frielinghaus H, Holderer O, Mattauch S, Monkenbusch M, Arend N, Richter D. Polymer enrichment decelerates surfactant membranes near interfaces. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 89:042303. [PMID: 24827247 DOI: 10.1103/physreve.89.042303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Indexed: 06/03/2023]
Abstract
Close to a planar surface, lamellar structures are imposed upon otherwise bulk bicontinuous microemulsions. Thermally induced membrane undulations are modified by the presence of the rigid interface. While it has been shown that a pure membrane's dynamics are accelerated close to the interface, we observed nearly unchanged relaxation rates for membranes spiked with large amphiphilic diblock copolymers. An increase of the polymer concentration by a factor of 2-3 for the first and second surfactant membrane layers was observed. We interpret the reduced relaxation times as the result of an interplay between the bending rigidity and the characteristic distance of the first surfactant membrane to the rigid interface, which causes the hydrodynamic and steric interface effects described in Seifert's theory. The influence of these effects on decorated membranes yields a reduction of the frequencies and an amplification of the amplitudes of long-wavelength undulations, which are in accordance to our experimental findings.
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Affiliation(s)
- F Lipfert
- Institute for Complex Systems 1, Forschungszentrum Jülich GmbH, D-52425 Jülich
| | - H Frielinghaus
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747 Garching
| | - O Holderer
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747 Garching
| | - S Mattauch
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747 Garching
| | - M Monkenbusch
- Institute for Complex Systems 1, Forschungszentrum Jülich GmbH, D-52425 Jülich
| | - N Arend
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747 Garching and Jülich Centre for Neutron Science (JCNS), Outstation at SNS, Oak Ridge, USA
| | - D Richter
- Institute for Complex Systems 1, Forschungszentrum Jülich GmbH, D-52425 Jülich and Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, D-85747 Garching
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7
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Frielinghaus H, Holderer O, Lipfert F, Kerscher M, Mattauch S, Richter D. Microemulsions as model fluids for enhanced oil recovery: dynamics adjacent to planar hydrophilic walls. EPJ Web of Conferences 2012. [DOI: 10.1051/epjconf/20123303005] [Citation(s) in RCA: 3] [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: 11/14/2022] Open
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Frielinghaus H, Kerscher M, Holderer O, Monkenbusch M, Richter D. Acceleration of membrane dynamics adjacent to a wall. Phys Rev E Stat Nonlin Soft Matter Phys 2012; 85:041408. [PMID: 22680476 DOI: 10.1103/physreve.85.041408] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Indexed: 06/01/2023]
Abstract
The dynamics of an induced lamellar microemulsion adjacent to a planar hydrophilic surface (45 ns) were found to be three times faster compared to the bicontinuous bulk structure (133 ns). For these investigations the grazing incidence technique for neutron spin echo spectroscopy has been developed to resolve the depth dependent near surface dynamics. The observation is rationalized in terms of membrane hydrodynamics, where the flow fields reflected by the surface lead to a crossover from classical to confined fluctuations, and faster dynamics on large length scales (also known as "lubrication") are predicted.
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Affiliation(s)
- H Frielinghaus
- Jülich Centre of Neutron Science, Forschungszentrum Jülich GmbH, Lichtenbergstrasse 1, D-85747 Garching, Germany
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Radulescu A, Pipich V, Frielinghaus H, Appavou MS. KWS-2, the high intensity / wideQ-range small-angle neutron diffractometer for soft-matter and biology at FRM II. ACTA ACUST UNITED AC 2012. [DOI: 10.1088/1742-6596/351/1/012026] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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10
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Zhang F, Roosen-Runge F, Skoda MWA, Jacobs RMJ, Wolf M, Callow P, Frielinghaus H, Pipich V, Prévost S, Schreiber F. Hydration and interactions in protein solutions containing concentrated electrolytes studied by small-angle scattering. Phys Chem Chem Phys 2012; 14:2483-93. [DOI: 10.1039/c2cp23460b] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bahadur J, Sen D, Mazumder S, Bhattacharya S, Frielinghaus H, Goerigk G. Origin of buckling phenomenon during drying of micrometer-sized colloidal droplets. Langmuir 2011; 27:8404-8414. [PMID: 21630693 DOI: 10.1021/la200827n] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The origin of the buckling of micrometer-sized colloidal droplets during evaporation-induced self-assembly (EISA) has been elucidated using electron microscopy and small-angle neutron scattering. Doughnut-like assembled grains with varying aspect ratios are formed during EISA at different physicochemical conditions. It has been revealed that this phenomenon is better explained by an existing hypothesis based on the formation of a viscoelastic shell of nanoparticles during drying than by other existing hypotheses based on the inertial instability of the initial droplets and hydrodynamic instability due to thermocapillary forces. This conclusion was further supported by the arrest of buckling through modification of the colloidal interaction in the initial dispersion.
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Affiliation(s)
- J Bahadur
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India.
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12
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Kerscher M, Busch P, Mattauch S, Frielinghaus H, Richter D, Belushkin M, Gompper G. Near-surface structure of a bicontinuous microemulsion with a transition region. Phys Rev E Stat Nonlin Soft Matter Phys 2011; 83:030401. [PMID: 21517443 DOI: 10.1103/physreve.83.030401] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 12/02/2010] [Indexed: 05/30/2023]
Abstract
The lamellar ordering of bicontinuous microemulsions adjacent to a planar hydrophilic wall is investigated experimentally by grazing-incidence small-angle neutron scattering and theoretically by computer simulations. It is shown that precise depth information in neutron scattering can be obtained by tuning the scattering length density of the overall microemulsion. Neutron reflectometry completes the characterization. The nucleation of a lamellar phase at the wall is observed, and a perforated lamellar transition region is identified at the lamellar-microemulsion interface. The thickness of the lamellar region is about 400 Å, which corresponds to two bilayers.
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Affiliation(s)
- M Kerscher
- Institute for Solid State Research, Neutron Scattering, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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Holderer O, Frielinghaus H, Byelov D, Monkenbusch M, Allgaier J, Richter D. Dynamical Properties of Decorated Lamellar Microemulsions in the Brush Regime. Z PHYS CHEM 2010. [DOI: 10.1524/zpch.2010.6102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The elastic constants of bicontinuous microemulsions, consisting of water, oil (decane) and a surfactant, can be modified by the addition of diblock-copolymers (boosting effect). A similar decoration of the surfactant membrane is possible in the lamellar phase. At high diblock copolymer densities, in the brush regime, a change in the dependence of the bending rigidity on the molecular size and concentration of the diblock copolymer is predicted theoretically. In particular a very strong dependence of the bending rigidity on the radius of gyration of the diblock copolymer (κ ∝ R
5) is predicted. We have studied the structure and dynamics of lamellar microemulsions by small angle neutron scattering (SANS) and neutron spin echo spectroscopy (NSE) in the brush regime, with high diblock copolymer density. Decyl polyglycol ether (C10E4) has been used as surfactant, the amphiphilic diblock-copolymers were polyethylenepropylene/polyethyleneoxide (PEP5–PEO5). The influence of the diblock copolymer concentration when entering the brush regime on the bending rigidity κ and the correlation length ξ will be discussed.
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14
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Frielinghaus H, Pipich V, Radulescu A, Heiderich M, Hanslik R, Dahlhoff K, Iwase H, Koizumi S, Schwahn D. Aspherical refractive lenses for small-angle neutron scattering. J Appl Crystallogr 2009. [DOI: 10.1107/s0021889809017919] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Aspherical neutron lenses are discussed in detail as focusing elements for existing small-angle neutron scattering (SANS) diffractometers. The conceptual design can be obtained by analytical equations, while computer simulations provide the intensity distribution of the primary beam, which is strongly correlated with the instrumental resolution and the minimal momentum transferQ. For large illuminated sample/lens areas of 50 mm diameter the aspherical lens design is essential, while spherical lenses are limited toca20 mm diameter with a 60% spherical aberration for standard SANS experiments. Scattering experiments on different samples proved the applicability and revealed the resolution limits of the two lens types. From theoretical considerations it is proposed that lens cooling can be used to reduce the thermal diffuse scattering.
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15
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Yan H, Frielinghaus H, Nykanen A, Ruokolainen J, Saiani A, Miller AF. Thermoreversible lysozyme hydrogels: properties and an insight into the gelation pathway. Soft Matter 2008; 4:1313-1325. [PMID: 32907277 DOI: 10.1039/b716966c] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The gelation behaviour of aqueous solutions of hen egg white lysozyme (HEWL) in the presence of 20 mM DTT in the concentration range 0.7 to 4.0 mM has been investigated using microDSC, FTIR, cryoTEM, SANS and oscillatory rheology. The macroscopic critical gelation concentration, Cgel, was found to be ∼ 3.0 mM. The disruption of the disulfide bonds by the DTT and the destabilisation of the protein were found to be a prerequisite for the formation of β-sheet rich fibrils under the mild conditions used in this work. Using our methodology the hydrogels obtained have a pH of 7, hence are suitable for cell culture, and are also thermoreversible. The hydrogel melting temperature was found to increase with increasing concentration and a similar structure was observed across the concentration range investigated. Our results suggest these systems are composed of a well defined regular network where single β-sheet rich fibrils (∼ 3 nm diameter) form initially, then two of these fibrils associate two-by-two to form junctions (∼ 6 nm diameter) and then on cooling further aggregate to form larger bundles of fibres. The network mesh size was found to decrease with increasing concentration. Our results suggest that below Cgel small unconnected gel-like aggregates exist that have a similar structure to the hydrogels obtained above Cgel. Using our data we propose a model for the denaturation and gelation behaviour of our system. During the first heating an α-helix to β-sheet molecular transition for the protein conformation occurs resulting in β-sheet rich fibrils forming through the self-assembly of β-sheet rich denaturated proteins. At high temperature the solution contains β-sheet rich fibrils with dissolved protein. On cooling an increase in the amount of β-sheet was observed via FTIR suggesting that as the temperature is decreased more and more protein forms β-sheet rich fibrils. At the gelation temperature these fibrils associate two-by-two to form the network junctions resulting in the macroscopic gelation of the sample. Our results suggest the network junctions are formed via specific hydrophobic interactions. The hydrogels elastic modulus was found to scale as C2.45 for C > Cgel.
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Affiliation(s)
- H Yan
- School of Chemical Engineering and Analytical Science, University of Manchester, Sackville Street, Manchester, UKM60 1QD.
| | - H Frielinghaus
- Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Garching, 85747, Germany
| | - A Nykanen
- Department of Engineering Physics and Mathematics and Center for New Materials, Helsinki University of Technology, P.O. Box 2200 TKK, Finland
| | - J Ruokolainen
- Department of Engineering Physics and Mathematics and Center for New Materials, Helsinki University of Technology, P.O. Box 2200 TKK, Finland
| | - A Saiani
- School of Materials, University of Manchester, Grosvenor Street, Manchester, UKM1 7HS
| | - A F Miller
- School of Chemical Engineering and Analytical Science, University of Manchester, Sackville Street, Manchester, UKM60 1QD.
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Abstract
We report experimental results obtained from SANS on microemulsion droplets connected by a telechelic polymer. Thanks to its ability to anchor droplets through its short stickers, the addition of this polymer leads to the formation of transient aggregates. Measurements were performed on samples at low surfactant content in such a way that the droplets appear to be isolated with a separation distance longer than the end-to-end distance of the polymer. The locally spherical structure of the micelles is unchanged in size upon polymer addition whereas the large rise in scattered intensity at low Q is due to the induced effective attractive interaction between droplets. The fitting model that we propose allows a quantitative description of the bridging effect.
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Affiliation(s)
- S Maccarrone
- Institut für Festkörperforschung, Forschungszentrum Jülich, 52428 Jülich, Germany.
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17
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Melnichenko YB, Wignall GD, Cole DR, Frielinghaus H. Adsorption of supercritical CO2 in aerogels as studied by small-angle neutron scattering and neutron transmission techniques. J Chem Phys 2007; 124:204711. [PMID: 16774368 DOI: 10.1063/1.2202324] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Small-angle neutron scattering (SANS) has been used to study the adsorption behavior of supercritical carbon dioxide (CO2) in porous Vycor glass and silica aerogels. Measurements were performed along two isotherms (T=35 and 80 degrees C) as a function of pressure (P) ranging from atmospheric up to 25 MPa, which corresponds to the bulk fluid densities ranging from rho(CO2) approximately 0 to 0.9 gcm3. The intensity of scattering from CO2-saturated Vycor porous glass can be described by a two-phase model which suggests that CO2 does not adsorb on the pore walls and fills the pore space uniformly. In CO2-saturated aerogels an adsorbed phase is formed with a density substantially higher that of the bulk fluid, and neutron transmission data were used to monitor the excess adsorption at different pressures. The results indicate that adsorption of CO2 is significantly stronger in aerogels than in activated carbons, zeolites, and xerogels due to the extremely high porosity and optimum pore size of these materials. SANS data revealed the existence of a compressed adsorbed phase with the average density approximately 1.07 gcm3, close to the density corresponding to closely packed van der Waals volume of CO2. A three-phase model [W. L. Wu, Polymer 23, 1907 (1982)] was used to estimate the volume fraction phi3 of the adsorbed phase as a function of the fluid density, and gave phi3 approximately 0.78 in the maximum adsorption regime around rho(CO2) approximately 0.374 gcm3. The results presented in this work demonstrate the utility of SANS combined with the transmission measurements to study the adsorption of supercritical fluids in porous materials.
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Affiliation(s)
- Y B Melnichenko
- Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA.
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18
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Holderer O, Frielinghaus H, Monkenbusch M, Allgaier J, Richter D, Farago B. Hydrodynamic effects in bicontinuous microemulsions measured by inelastic neutron scattering. Eur Phys J E Soft Matter 2007; 22:157-61. [PMID: 17356800 DOI: 10.1140/epje/e2007-00021-2] [Citation(s) in RCA: 9] [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: 11/22/2006] [Indexed: 05/14/2023]
Abstract
The dynamical properties of bicontinuous microemulsions have been studied with neutron spin echo spectroscopy around length scales corresponding to the correlation peak q(0). Comparison of samples with different contrasts for neutrons shed light on the two modes dominated either by variation of the oil/water difference or surfactant concentration in the hydrodynamic regime. The results have been compared to theoretical predictions of the relaxation rates of bicontinuous microemulsions by Nonomura and Ohta [M. Nonomura, T. Ohta, J. Chem. Phys. 110, 7516 (1999)]. The influence of modification of the surfactant layer bending constants in the microemulsion by addition of homopolymers (polyethylenepropylene: PEP(X) and polyethyleneoxide: PEO(X), X=5 kg/mol), dissolved in the oil phase and water, has been investigated.
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Affiliation(s)
- O Holderer
- Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
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19
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Byelov D, Frielinghaus H, Holderer O, Allgaier J, Richter D. Microemulsion efficiency boosting and the complementary effect. 1. Structural properties. Langmuir 2004; 20:10433-10443. [PMID: 15544370 DOI: 10.1021/la049317t] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Amphiphilic diblock copolymers added to microemulsions proved to enhance the efficiency of surfactants dramatically. The complementary effect of homopolymers is considered in the current work. A possible application of the homopolymer addition could be the viscosity tuning of the microemulsion without changing the considered bicontinuous phase. Furthermore, (homo)polymers are added for many other reasons in technical applications. A theory by Eisenriegler predicts a decreased efficiency when homopolymers are added. In further experiments, the simultaneous addition of homopolymers and diblock copolymers probes whether the two opposite effects superpose and allow for a compensation. Then, efficiency and viscosity are adjustable independently. Experimentally, phase diagrams are investigated and the microscopic structure is measured by small-angle neutron scattering. Within the presented models, both experimental methods are compared and discussed on the basis of the surfactant membrane bending moduli. The homopolymer effect is about 7 times larger than that theoretically predicted, and the superposition of the two polymer effects allows for a compensation with an optionally tunable viscosity.
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Affiliation(s)
- D Byelov
- Forschungszentrum Jülich GmbH, Institut für Festkörperforschung, D-52425 Jülich, Germany
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Melnichenko YB, Wignall GD, Cole DR, Frielinghaus H. Density fluctuations near the liquid-gas critical point of a confined fluid. Phys Rev E Stat Nonlin Soft Matter Phys 2004; 69:057102. [PMID: 15244976 DOI: 10.1103/physreve.69.057102] [Citation(s) in RCA: 4] [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: 08/27/2003] [Indexed: 05/24/2023]
Abstract
We report the results of an experimental study of the effect of a dilute silica network on liquid-gas critical phenomena in carbon dioxide (CO2). Using small-angle neutron scattering, we measured the correlation length of the density fluctuations in bulk (xi(bulk)) and confined CO2 (xi(conf)) as a function of temperature and average fluid density. We find that quenched disorder induced by an aerogel suppresses density fluctuations: xi(conf) loses the Ising model divergence characteristic of xi(bulk) and does not exceed the size of pores in the homogeneous region.
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Affiliation(s)
- Y B Melnichenko
- Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6393, USA
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Jeng U, Lin TL, Hu Y, Chang TS, Canteenwala T, Chiang LY, Frielinghaus H. Study on Aqueous Mixtures of Fullerene-Based Star Ionomers and Sodium Dodecyl Sulfate Using Small Angle Scattering with Contrast Variation. J Phys Chem A 2002. [DOI: 10.1021/jp020346r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- U. Jeng
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
| | - T.-L. Lin
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
| | - Y. Hu
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
| | - T.-S. Chang
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
| | - T. Canteenwala
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
| | - L. Y. Chiang
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
| | - H. Frielinghaus
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30043, Taiwan, Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan, and Institut für Festkörperforschung Forschungszentrum, Jülich GmbH D-52425, Jülich, Germany
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Frielinghaus H, Hermsdorf N, Sigel R, Almdal K, Mortensen K, Hamley IW, Messé, L, Corvazier L, Ryan AJ, van Dusschoten D, Wilhelm M, Floudas G, Fytas G. Blends of AB/BC Diblock Copolymers with a Large Interaction Parameter χ. Macromolecules 2001. [DOI: 10.1021/ma010233q] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - N. Hermsdorf
- Institut für Polymerforschung Dresden, D-01069 Dresden, Germany
| | - R. Sigel
- Max-Planck-Institut für Kolloid und Grenzflächenforschung, D-14424 Potsdam, Germany
| | | | | | - I. W. Hamley
- School of Chemistry, University of Leeds, Leeds LS2 9JT, UK
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Mortensen K, Schwahn D, Frielinghaus H, Almdal K. Ternary mixture of a homopolymer blend and diblock copolymer studied near the Lifshitz composition by small-angle neutron scattering. J Appl Crystallogr 2000. [DOI: 10.1107/s0021889899013187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Frielinghaus H, Schwahn D, Mortensen K, Willner L, Almdal K. Pressure and Temperature Effects in Homopolymer Blends and Diblock Copolymers. J Appl Crystallogr 1997. [DOI: 10.1107/s0021889897001404] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Thermal composition fluctuations in a homogeneous binary polymer blend and in a diblock copolymer were measured by small-angle neutron scattering as a function of temperature and pressure. The experimental data were analyzed with theoretical expressions, including the important effect of thermal fluctuations. Phase boundaries, the Flory–Huggins interaction parameter and the Ginzburg number were obtained. The packing of the molecules changes with pressure. Therefore, the degree of thermal fluctuation as a function of packing and temperature was studied. While in polymer blends packing leads, in some respects, to a universal behaviour, such behaviour is not found in diblock copolymers. It is shown that the Ginzburg number decreases with pressure sensitively in blends, while it is constant in diblock copolymers. The Ginzburg number is an estimation of the transition between the universality classes of the `mean-field' approximation and the three-dimensional Ising model. The phase boundaries in blends increase with pressure, while the phase boundary of the studied block copolymer shows an unusual shape: with increasing pressure it first decreases and then increases. Its origin is an increase of the entropic and of the enthalpic parts, respectively, of the Flory–Huggins interaction parameter.
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Schwahn D, Frielinghaus H, Mortensen K, Almdal K. Temperature and Pressure Dependence of the Order Parameter Fluctuations, Conformational Compressibility, and the Phase Diagram of the PEP-PDMS Diblock Copolymer. Phys Rev Lett 1996; 77:3153-3156. [PMID: 10062147 DOI: 10.1103/physrevlett.77.3153] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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