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Richard MI, Labat S, Dupraz M, Li N, Bellec E, Boesecke P, Djazouli H, Eymery J, Thomas O, Schülli TU, Santala MK, Leake SJ. Bragg coherent diffraction imaging of single 20 nm Pt particles at the ID01-EBS beamline of ESRF. J Appl Crystallogr 2022; 55:621-625. [PMID: 35719306 PMCID: PMC9172036 DOI: 10.1107/s1600576722002886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/15/2022] [Indexed: 11/24/2022] Open
Abstract
This work demonstrates three-dimensional Bragg coherent diffraction imaging of single 20 nm Pt particles at the ID01-EBS beamline of ESRF. Electronic or catalytic properties can be modified at the nanoscale level. Engineering efficient and specific nanomaterials requires the ability to study their complex structure–property relationships. Here, Bragg coherent diffraction imaging was used to measure the three-dimensional shape and strain of platinum nanoparticles with a diameter smaller than 30 nm, i.e. significantly smaller than any previous study. This was made possible by the realization of the Extremely Brilliant Source of ESRF, The European Synchrotron. This work demonstrates the feasibility of imaging the complex structure of very small particles in three dimensions and paves the way towards the observation of realistic catalytic particles.
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Richard MI, Fernández S, Hofmann JP, Gao L, Chahine GA, Leake SJ, Djazouli H, De Bortoli Y, Petit L, Boesecke P, Labat S, Hensen EJM, Thomas O, Schülli T. Reactor for nano-focused x-ray diffraction and imaging under catalytic in situ conditions. Rev Sci Instrum 2017; 88:093902. [PMID: 28964168 DOI: 10.1063/1.5000015] [Citation(s) in RCA: 4] [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: 06/07/2023]
Abstract
A reactor cell for in situ studies of individual catalyst nanoparticles or surfaces by nano-focused (coherent) x-ray diffraction has been developed. Catalytic reactions can be studied in flow mode in a pressure range of 10-2-103 mbar and temperatures up to 900 °C. This instrument bridges the pressure and materials gap at the same time within one experimental setup. It allows us to probe in situ the structure (e.g., shape, size, strain, faceting, composition, and defects) of individual nanoparticles using a nano-focused x-ray beam. Here, the setup was used to observe strain and facet evolution of individual model Pt catalysts during in situ experiments. It can be used for heating other (non-catalytically active) nanoparticles (e.g., nanowires) in inert or reactive gas atmospheres or vacuum as well.
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Affiliation(s)
- M-I Richard
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - S Fernández
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - J P Hofmann
- Laboratory of Inorganic Materials Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands
| | - L Gao
- Laboratory of Inorganic Materials Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands
| | - G A Chahine
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - S J Leake
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - H Djazouli
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - Y De Bortoli
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - L Petit
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - P Boesecke
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
| | - S Labat
- Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397 Marseille, France
| | - E J M Hensen
- Laboratory of Inorganic Materials Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands
| | - O Thomas
- Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397 Marseille, France
| | - T Schülli
- ID01/ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex, France
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Schmiele M, Busch S, Morhenn H, Schindler T, Schmutzler T, Schweins R, Lindner P, Boesecke P, Westermann M, Steiniger F, Funari SS, Unruh T. Structural Characterization of Lecithin-Stabilized Tetracosane Lipid Nanoparticles. Part I: Emulsions. J Phys Chem B 2016; 120:5505-12. [DOI: 10.1021/acs.jpcb.6b02519] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Schmiele
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - S. Busch
- German
Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz
Zentrum (MLZ), Helmholtz-Zentrum Geesthacht GmbH, Lichtenbergstr.
1, 85747 Garching, Germany
| | - H. Morhenn
- Heinz
Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85747 Garching, Germany
| | - T. Schindler
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - T. Schmutzler
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - R. Schweins
- DS/LSS, Institut Laue-Langevin (ILL), 71 Avenue des Martyrs, CS20156, 38042 Grenoble CEDEX 9, France
| | - P. Lindner
- DS/LSS, Institut Laue-Langevin (ILL), 71 Avenue des Martyrs, CS20156, 38042 Grenoble CEDEX 9, France
| | - P. Boesecke
- European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, CS40220, 38042 Grenoble CEDEX 9, France
| | - M. Westermann
- Center for Electron Microscopy of the Jena University Hospital, Ziegelmühlenweg 1, 07743 Jena, Germany
| | - F. Steiniger
- Center for Electron Microscopy of the Jena University Hospital, Ziegelmühlenweg 1, 07743 Jena, Germany
| | | | - T. Unruh
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
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4
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Schmiele M, Busch S, Morhenn H, Schindler T, Schmutzler T, Schweins R, Lindner P, Boesecke P, Westermann M, Steiniger F, Funari SS, Unruh T. Structural Characterization of Lecithin-Stabilized Tetracosane Lipid Nanoparticles. Part II: Suspensions. J Phys Chem B 2016; 120:5513-26. [DOI: 10.1021/acs.jpcb.6b02520] [Citation(s) in RCA: 8] [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: 11/29/2022]
Affiliation(s)
- M. Schmiele
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - S. Busch
- German
Engineering Materials Science Centre (GEMS) at Heinz Maier-Leibnitz
Zentrum (MLZ), Helmholtz-Zentrum Geesthacht GmbH, Lichtenbergstr.
1, 85747 Garching, Germany
| | - H. Morhenn
- Heinz
Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 85747 Garching, Germany
| | - T. Schindler
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - T. Schmutzler
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
| | - R. Schweins
- DS/LSS, Institut Laue-Langevin (ILL), 71 Avenue des Martyrs, CS20156, 38042 Grenoble CEDEX 9, France
| | - P. Lindner
- DS/LSS, Institut Laue-Langevin (ILL), 71 Avenue des Martyrs, CS20156, 38042 Grenoble CEDEX 9, France
| | - P. Boesecke
- European Synchrotron Radiation Facility (ESRF), 71 Avenue des Martyrs, CS40220, 38042 Grenoble CEDEX 9, France
| | - M. Westermann
- Center for Electron Microscopy of the Jena University Hospital, Ziegelmühlenweg 1, 07743 Jena, Germany
| | - F. Steiniger
- Center for Electron Microscopy of the Jena University Hospital, Ziegelmühlenweg 1, 07743 Jena, Germany
| | | | - T. Unruh
- Professur
für Nanomaterialcharakterisierung (Streumethoden), Friedrich−Alexander−Universität Erlangen−Nürnberg, Staudtstr. 3, 91058 Erlangen, Germany
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Gupta HS, Krauss S, Kerschnitzki M, Karunaratne A, Dunlop JWC, Barber AH, Boesecke P, Funari SS, Fratzl P. Intrafibrillar plasticity through mineral/collagen sliding is the dominant mechanism for the extreme toughness of antler bone. J Mech Behav Biomed Mater 2013; 28:366-82. [PMID: 23707600 DOI: 10.1016/j.jmbbm.2013.03.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [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: 11/20/2012] [Revised: 03/24/2013] [Accepted: 03/29/2013] [Indexed: 11/17/2022]
Abstract
The inelastic deformability of the mineralised matrix in bones is critical to their high toughness, but the nanoscale mechanisms are incompletely understood. Antler is a tough bone type, with a nanostructure composed of mineralised collagen fibrils ∼100nm diameter. We track the fibrillar deformation of antler tissue during cyclic loading using in situ synchrotron small-angle X-ray diffraction (SAXD), finding that residual strain remains in the fibrils after the load was removed. During repeated unloading/reloading cycles, the fibril strain shows minimal hysteresis when plotted as a function of tissue strain, indicating that permanent plastic strain accumulates inside the fibril. We model the tensile response of the mineralised collagen fibril by a two - level staggered model - including both elastic - and inelastic regimes - with debonding between mineral and collagen within fibrils triggering macroscopic inelasticity. In the model, the subsequent frictional sliding at intrafibrillar mineral/collagen interfaces accounts for subsequent inelastic deformation of the tissue in tension. The model is compared to experimental measurements of fibrillar and mineral platelet strain during tensile deformation, measured by in situ synchrotron SAXD and wide-angle X-ray diffraction (WAXD) respectively, as well as macroscopic tissue stress and strain. By fitting the model predictions to experimentally observed parameters like the yield point, elastic modulus and post-yield slope, extremely good agreement is found between the model and experimental data at both the macro- and at the nanoscale. Our results provide strong evidence that intrafibrillar sliding between mineral and collagen leads to permanent plastic strain at both the fibril and the tissue level, and that the energy thus dissipated is a significant factor behind the high toughness of antler bone.
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Affiliation(s)
- H S Gupta
- Queen Mary University of London, School of Engineering and Materials Science, Mile End Road, London E1 4NS, UK.
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Cornelius TW, Schiedt B, Severin D, Pépy G, Toulemonde M, Apel PY, Boesecke P, Trautmann C. Nanopores in track-etched polymer membranes characterized by small-angle x-ray scattering. Nanotechnology 2010; 21:155702. [PMID: 20332555 DOI: 10.1088/0957-4484/21/15/155702] [Citation(s) in RCA: 10] [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: 05/29/2023]
Abstract
Nanochannels and nanowires with diameters ranging from 30 to 400 nm were produced by etching ion tracks in thin polyarylate and polycarbonate foils. The shape and the size distribution of dry and wet nanochannels, as well as of nanowires grown therein, were examined by small-angle x-ray scattering. The x-ray intensity as a function of the scattering vector exhibits pronounced oscillations showing that both the channels and the wires have a highly cylindrical geometry and a very narrow size distribution. UV exposure before chemical etching significantly improves the monodispersity of the nanopores. For fixed etching conditions, the scattering patterns provide evidence that the diameter of dry and water-filled channels as well as for embedded nanowires are identical, demonstrating that the pores in the polymer are completely filled.
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Affiliation(s)
- T W Cornelius
- GSI Helmholtz Centre for Heavy Ion Research, Planckstrasse 1, 64291 Darmstadt, Germany.
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Gupta HS, Seto J, Krauss S, Boesecke P, Screen HRC. In situ multi-level analysis of viscoelastic deformation mechanisms in tendon collagen. J Struct Biol 2009; 169:183-91. [PMID: 19822213 DOI: 10.1016/j.jsb.2009.10.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 09/26/2009] [Accepted: 10/05/2009] [Indexed: 11/29/2022]
Abstract
Tendon is a hydrated multi-level fibre composite, in which time-dependent behaviour is well established. Studies indicate significant stress relaxation, considered important for optimising tissue stiffness. However, whilst this behaviour is well documented, the mechanisms associated with the response are largely unknown. This study investigates the sub-structural mechanisms occurring during stress relaxation at both the macro (fibre) and nano (fibril) levels of the tendon hierarchy. Stress relaxation followed a two-stage exponential behaviour, during which structural changes were visible at the fibre and fibril levels. Fibril relaxation and fibre sliding showed a double exponential response, while fibre sliding was clearly the largest contributor to relaxation. The amount of stress relaxation and sub-structural reorganisation increased with increasing load increments, but fibre sliding was consistently the largest contributor to stress relaxation. A simple model of tendon viscoelasticity at the fibril and fibre levels has been developed, capturing this behaviour by serially coupling a Voigt element (collagen fibril), with two Maxwell elements (non-collagenous matrix between fibrils and fibres). This multi-level analysis provides a first step towards understanding how sub-structural interactions contribute to viscoelastic behaviour. It indicates that nano- and micro-scale shearing are significant dissipative mechanisms, and the kinetics of relaxation follows a two-stage exponential decay, well fitted by serially coupled viscoelastic elements.
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Affiliation(s)
- H S Gupta
- School of Engineering and Materials Science, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
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8
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Belloni L, Delsanti M, Fontaine P, Muller F, Guenoun P, Mays JW, Boesecke P, Alba M. Counterion distribution in urchinlike charged copolymer micelles Monte Carlo simulation and small angle x-ray scattering. J Chem Phys 2003. [DOI: 10.1063/1.1607911] [Citation(s) in RCA: 8] [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: 11/14/2022] Open
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Wiedenmann A, Hoell A, Kammel M, Boesecke P. Field-induced pseudocrystalline ordering in concentrated ferrofluids. Phys Rev E Stat Nonlin Soft Matter Phys 2003; 68:031203. [PMID: 14524754 DOI: 10.1103/physreve.68.031203] [Citation(s) in RCA: 15] [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: 12/13/2002] [Indexed: 05/24/2023]
Abstract
Concentrated surfactant stabilized cobalt ferrofluids up to 6 vol % Co have been studied by small-angle scattering using polarized neutrons and synchrotron x rays. The combination of these techniques allowed the magnetic and nuclear form factors to be reliably separated from the structure factors. Above 1 vol % Co, inter particle interactions are induced by an applied external magnetic field that gives rise to pseudocrystalline ordering of cobalt core-shell particles. Particles are arranged in hexagonal planes, with the magnetic moments aligned parallel to the [110] direction. Two types of equivalent textures were found to be present simultaneously, corresponding to a stacking of the hexagonal planes in horizontal and vertical direction. The in-plane nearest-neighbor distance is almost independent of the concentration and temperatures, whereas the distance between the neighboring planes, c, strongly varies from sample to sample. In addition, segments of chains of particles with parallel moments are aligned along the magnetic field and frozen-in when the carrier liquid is solidified. The field induced pseudocrystalline lamellar hexagonal particle arrangement, observed experimentally in colloidal magnetic liquids, confirms predictions from molecular-dynamics and Monte Carlo simulations.
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Affiliation(s)
- A Wiedenmann
- Hahn-Meitner-Institut Berlin, Department SF3, Glienickerstrasse 100, D-14109 Berlin, Germany.
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Panine P, Urban V, Boesecke P, Narayanan T. Combined small- and wide-angle X-ray scattering study of early stages of polymer crystallization. J Appl Crystallogr 2003. [DOI: 10.1107/s0021889803008513] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [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
The early stage of melt crystallization in low-density polyethylene was investigated by simultaneous time-resolved small-angle and wide-angle X-ray scattering (SAXS/WAXS) techniques. The high detectivity of the two-dimensional detectors together with the large photon flux of an undulator source permitted the collection of SAXS and WAXS patterns with nearly single-photon sensitivity and sub-second time resolution. As a result, the crystalline fraction well below 0.001 can be reliably detected and the apparent induction time is considerably reduced (<10 s). The time evolution of both the SAXS invariant and the degree of crystallinity follow the well established Avrami-type growth law. Despite the orders of magnitude improvement in sensitivity, the difference in the onset time of SAXS and WAXS signals is not significant. The behaviour of the SAXS data in the very early stages is not consistent with spinodal decomposition mechanism as described by the linearized Cahn–Hilliard theory.
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Maurizio C, Longo A, Martorana A, Cattaruzza E, D'Acapito F, Gonella F, de Julian C, Mattei G, Mazzoldi P, Padovani S, Boesecke P. Grazing-incidence small-angle X-ray scattering and X-ray diffraction from magnetic clusters obtained by Co + Ni sequential ion implantation in silica. J Appl Crystallogr 2003. [DOI: 10.1107/s0021889803006137] [Citation(s) in RCA: 5] [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: 11/11/2022] Open
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Stuhrmann HB, Carpentier P, Boesecke P, Bois JM, Chesne ML, Kahn R, Kozielski-Stuhrmann S, Vicat J. How critical are absorption corrections for phasing Bragg reflections with the MAD method at wavelengths between 3 and 6 Å? Acta Crystallogr A 2002. [DOI: 10.1107/s0108767302088463] [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: 11/10/2022] Open
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Abstract
When isometrically contracting muscles are subjected to a quick release followed by a shortening ramp of appropriate speed (V(o)), tension decays from its value at the isometric plateau (P(o)) to <0. 05 P(o) with the same time course as the quick part of the release; thereafter, tension remains at a negligible level for the duration of the shortening ramp. X-ray diffraction data obtained under these conditions provide evidence that 1) at V(o) very few heads form an actomyosin complex, while the number of heads doing so at P(o) is significant; 2) relative to rest the actin filament at V(o) is approximately 0.12% shorter and more twisted, while it is approximately 0.3% longer and less twisted at P(o); and 3) the myosin heads attaching to actin during force development do so against a thin filament compliance of at least 0.646 +/- 0.046% nm per P(o).
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Affiliation(s)
- J Bordas
- LLS-IFAE, Universitat Aut-noma de Barcelona, E-08193 Bellaterra, Barcelona, Spain.
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Reconditi M, Dobbie I, Irving M, Diat O, Boesecke P, Linari M, Piazzesi G, Lombardi V. Myosin head movements during isometric contraction studied by X-ray diffraction of single frog muscle fibres. Adv Exp Med Biol 1999; 453:265-70. [PMID: 9889838 DOI: 10.1007/978-1-4684-6039-1_31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Time resolved X-ray diffraction experiments in single muscle fibres of the frog at 2.15 microns sarcomere length and 4 degrees C were performed at ID2 (SAXS), ESRF, Grenoble (France) to investigate the structural aspects of cross-bridge action during the development of the isometric tetanic tension (T0). Changes in the low angle myosin-based reflections were measured with 5 ms time resolution by signal averaging data collected with a 10 m camera length and a 2D gas-filled detector. Upon activation the intensity of the first order myosin layer line reflection, I(M1), and the intensity of the second order meridional reflection, I(M2), reduced practically to zero with a half-time which leads the tension rise by 15-20 ms. The complex changes of the intensity of the third order myosin meridional reflection, I(M3), and the increase of its axial spacing from 14.34 nm (at rest) to 14.57 nm (at T0) could be analysed by assuming that they were the result of the combination of the time dependent modulation in intensity of two closely spaced periodicities, one at 14.34 nm, characteristics of the myosin molecule at rest and the other at 14.57 nm, assumed by the myosin as a consequence of the activation and force production. I(14.34) drops monotonically in advance to isometric tension development with a half-time similar to that of I(M1) and I(M2), while I(14.57) rises from zero to a maximum in parallel with tension.
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Piazzesi G, Reconditi M, Dobbie I, Linari M, Boesecke P, Diat O, Irving M, Lombardi V. Changes in conformation of myosin heads during the development of isometric contraction and rapid shortening in single frog muscle fibres. J Physiol 1999; 514 ( Pt 2):305-12. [PMID: 9852315 PMCID: PMC2269081 DOI: 10.1111/j.1469-7793.1999.305ae.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. Two-dimensional X-ray diffraction patterns were recorded at the European Synchrotron Radiation Facility from central segments of intact single muscle fibres of Rana temporaria with 5 ms time resolution during the development of isometric contraction. Shortening at ca 0.8 times the maximum velocity was also imposed at the isometric tetanus plateau. 2. The first myosin-based layer line (ML1) and the second myosin-based meridional reflection (M2), which are both strong in resting muscle, were completely abolished at the plateau of the isometric tetanus. The third myosin-based meridional reflection (M3), arising from the axial repeat of the myosin heads along the filaments, remained intense but its spacing changed from 14.34 to 14.56 nm. The intensity change of the M3 reflection, IM3, could be explained as the sum of two components, I14.34 and I14.56, arising from myosin head conformations characteristic of rest and isometric contraction, respectively. 3. The amplitudes (A) of the X-ray reflections, which are proportional to the fraction of myosin heads in each conformation, changed with half-times that were similar to that of isometric force development, which was 33.5 +/- 2. 0 ms (mean +/- s.d., 224 tetani from three fibres, 4 C), measured from the end of the latent period. We conclude that the myosin head conformation changes synchronously with force development, at least within the 5 ms time resolution of these measurements. 4. The changes in the X-ray reflections during rapid shortening have two temporal components. The rapid decrease in intensity of the 14.56 nm reflection at the start of shortening is likely to be due to tilting of myosin heads attached to actin. The slower changes in the other reflections were consistent with a return to the resting conformation of the myosin heads that was about 60 % complete after shortening of 70 nm per half-sarcomere.
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Affiliation(s)
- G Piazzesi
- Dipartimento di Scienze Fisiologiche, Università degli Studi di Firenze, I-50134 Firenze, Italy
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