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Heymann JB. The Ewald sphere/focus gradient does not limit the resolution of cryoEM reconstructions. J Struct Biol X 2022; 7:100083. [PMID: 36632443 PMCID: PMC9826812 DOI: 10.1016/j.yjsbx.2022.100083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/09/2022] [Accepted: 12/29/2022] [Indexed: 12/31/2022] Open
Abstract
In our quest to solve biomolecular structures to higher resolutions in cryoEM, care must be taken to deal with all aspects of image formation in the electron microscope. One of these is the Ewald sphere/focus gradient that derives from the scattering geometry in the microscope and its implications for recovering high resolution and handedness information. While several methods to deal with it has been proposed and implemented, there are still questions as to the correct approach. At the high acceleration voltages used for cryoEM, the traditional projection approximation that ignores the Ewald sphere breaks down around 2-3 Å and with large particles. This is likely not crucial for most biologically interesting molecules, but is required to understand detail about catalytic events, molecular orbitals, orientation of bound water molecules, etc. Through simulation I show that integration along the Ewald spheres in frequency space during reconstruction, the "simple insertion method" is adequate to reach resolutions to the Nyquist frequency. Both theory and simulations indicate that the handedness information encoded in such phases is irretrievably lost in the formation of real space images. The conclusion is that correct reconstruction along the Ewald spheres avoids the limitations of the projection approximation.
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Affiliation(s)
- J. Bernard Heymann
- National Cryo-EM Program, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, MD 21701, USA
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2
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Sciortino F, Cretu O, Karanikolas V, Grasset F, Cordier S, Ariga K, Kuroda T, Kimoto K. Surface Plasmon Tunability of Core-Shell Au@Mo 6 Nanoparticles by Shell Thickness Modification. J Phys Chem Lett 2022; 13:2150-2157. [PMID: 35226485 DOI: 10.1021/acs.jpclett.1c03853] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Plasmon resonances of noble metal nanoparticles are used to enhance light-matter interactions in the nanoworld. The nanoparticles' optical response depends strongly on the dielectric permittivity of the surrounding medium. We show that the plasmon resonance energy of core-shell Au@Mo6 nanoparticles can be tuned from 2.4 to 1.6 eV by varying the thickness of their Mo6 cluster shells between zero and 70 nm, when the core diameter is fixed at 100 nm. We probe their plasmonic response by performing nanometer-resolution plasmon mapping on individual nanoparticles, using electron energy-loss spectroscopy inside a transmission electron microscope. Our experimental results are corroborated by numerical simulations performed using boundary element methods. The simulations predict a similar dependency for the extinction energy, showing that this effect could also be observed by light-optical experiments outside the electron microscope, although limited by the size distribution of the nanoparticles in solution and the substantial scattering effects.
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Affiliation(s)
- Flavien Sciortino
- Université Grenoble Alpes, CNRS, DCM UMR 5250, Grenoble F-38000, France
| | | | | | - Fabien Grasset
- Univ. Rennes, CNRS, Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226, Rennes F-35000, France
| | - Stéphane Cordier
- Univ. Rennes, CNRS, Institut des Sciences Chimiques de Rennes (ISCR), UMR 6226, Rennes F-35000, France
| | - Katsuhiko Ariga
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan
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3
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Zhang H, Jimbo Y, Niwata A, Ikeda A, Yasuhara A, Ovidiu C, Kimoto K, Kasaya T, Miyazaki HT, Tsujii N, Wang H, Yamauchi Y, Fujita D, Kitamura SI, Manabe H. High-endurance micro-engineered LaB 6 nanowire electron source for high-resolution electron microscopy. NATURE NANOTECHNOLOGY 2022; 17:21-26. [PMID: 34750559 DOI: 10.1038/s41565-021-00999-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 09/06/2021] [Indexed: 06/13/2023]
Abstract
The size tunability and chemical versatility of nanostructures enable electron sources of high brightness and temporal coherence, both of which are important characteristics for high-resolution electron microscopy1-3. Despite intensive research efforts in the field, so far, only conventional field emitters based on a bulk tungsten (W) needle have been able to yield atomic-resolution images. The absence of viable alternatives is in part caused by insufficient fabrication precision for nanostructured sources, which require an alignment precision of subdegree angular deviation of a nanometre-sized emission area with the macroscopic emitter axis4. To overcome this challenge, in this work we micro-engineered a LaB6 nanowire-based electron source that emitted a highly collimated electron beam with good lateral and angular alignment. We integrated a passive collimator structure into the support needle tip for the LaB6 nanowire emitter. The collimator formed an axially symmetric electric field around the emission tip of the nanowire. Furthermore, by means of micromanipulation, the support needle tip was bent to align the emitted electron beam with the emitter axis. After installation in an aberration-corrected transmission electron microscope, we characterized the performance of the electron source in a vacuum of 10-8 Pa and achieved atomic resolution in both broad-beam and probe-forming modes at 60 kV beam energy. The natural, unmonochromated 0.20 eV electron energy loss spectroscopy resolution, 20% probe-forming efficiency and 0.4% probe current peak-to-peak noise ratio paired with modest vacuum requirements make the LaB6 nanowire-based electron source an attractive alternative to the standard W-based sources for low-cost electron beam instruments.
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Affiliation(s)
- Han Zhang
- Research Center for Advanced Material Characterization, National Institute for Materials Science, Tsukuba, Japan.
| | - Yu Jimbo
- JEOL Ltd, Akishima, Tokyo, Japan
| | | | | | | | - Cretu Ovidiu
- Research Center for Advanced Material Characterization, National Institute for Materials Science, Tsukuba, Japan
| | - Koji Kimoto
- Research Center for Advanced Material Characterization, National Institute for Materials Science, Tsukuba, Japan
| | - Takeshi Kasaya
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Hideki T Miyazaki
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Naohito Tsujii
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Hongxin Wang
- Research Center for Advanced Material Characterization, National Institute for Materials Science, Tsukuba, Japan
| | - Yasushi Yamauchi
- Research Center for Advanced Material Characterization, National Institute for Materials Science, Tsukuba, Japan
| | - Daisuke Fujita
- Research Center for Advanced Material Characterization, National Institute for Materials Science, Tsukuba, Japan
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4
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Cretu O, Ishizuka A, Yanagisawa K, Ishizuka K, Kimoto K. Atomic-Scale Electrical Field Mapping of Hexagonal Boron Nitride Defects. ACS NANO 2021; 15:5316-5321. [PMID: 33577281 DOI: 10.1021/acsnano.0c10849] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The distribution of electric fields in hexagonal boron nitride is mapped down to the atomic level inside a scanning transmission electron microscope by using the recently introduced technique of differential phase contrast imaging. The maps are calculated and displayed in real time, along with conventional annular dark-field images, through the use of custom-developed hardware and software. An increased electric field is observed around boron monovacancies and subsequently mapped and measured relative to the perfect lattice. The edges of extended defects feature enhanced electric fields, which can be used to trap diffusing adatoms. The magnitude of the electric field produced by the different types of edges is compared to monolayer areas, confirming previous predictions regarding their stability. These observations provide insight into the properties of this interesting material, serving as a suitable platform on which to test the limits of this technique, and encourage further work, such as dynamic experiments coupled with in situ techniques.
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Affiliation(s)
- Ovidiu Cretu
- Electron Microscopy Group, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
| | - Akimitsu Ishizuka
- HREM Research, Inc., 14-48 Matsukazedai, Higashimatsuyama, Saitama 355-0055, Japan
| | - Keiichi Yanagisawa
- Electron Microscopy Group, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
| | - Kazuo Ishizuka
- HREM Research, Inc., 14-48 Matsukazedai, Higashimatsuyama, Saitama 355-0055, Japan
| | - Koji Kimoto
- Electron Microscopy Group, National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan
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5
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Cheung SC, Shin JY, Lau Y, Chen Z, Sun J, Zhang Y, Müller MA, Eremin IM, Wright JN, Pasupathy AN. Dictionary learning in Fourier-transform scanning tunneling spectroscopy. Nat Commun 2020; 11:1081. [PMID: 32102995 PMCID: PMC7044214 DOI: 10.1038/s41467-020-14633-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 01/17/2020] [Indexed: 11/15/2022] Open
Abstract
Modern high-resolution microscopes are commonly used to study specimens that have dense and aperiodic spatial structure. Extracting meaningful information from images obtained from such microscopes remains a formidable challenge. Fourier analysis is commonly used to analyze the structure of such images. However, the Fourier transform fundamentally suffers from severe phase noise when applied to aperiodic images. Here, we report the development of an algorithm based on nonconvex optimization that directly uncovers the fundamental motifs present in a real-space image. Apart from being quantitatively superior to traditional Fourier analysis, we show that this algorithm also uncovers phase sensitive information about the underlying motif structure. We demonstrate its usefulness by studying scanning tunneling microscopy images of a Co-doped iron arsenide superconductor and prove that the application of the algorithm allows for the complete recovery of quasiparticle interference in this material. Aperiodic structure imaging suffers limitations when utilizing Fourier analysis. The authors report an algorithm that quantitatively overcomes these limitations based on nonconvex optimization, demonstrated by studying aperiodic structures via the phase sensitive interference in STM images.
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Affiliation(s)
- Sky C Cheung
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - John Y Shin
- Department of Physics, Columbia University, New York, NY, 10027, USA
| | - Yenson Lau
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - Zhengyu Chen
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - Ju Sun
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - Yuqian Zhang
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA
| | - Marvin A Müller
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Ilya M Eremin
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, 44801, Bochum, Germany.,National University of Science and Technology MISiS, 119049, Moscow, Russian Federation
| | - John N Wright
- Department of Electrical Engineering, Columbia University, New York, NY, 10027, USA.
| | - Abhay N Pasupathy
- Department of Physics, Columbia University, New York, NY, 10027, USA.
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Ohwada M, Mizukoshi Y, Shimokawa T, Hayashi N, Hayasaka Y, Konno TJ. Atomic and nanoscale imaging of a cellulose nanofiber and Pd nanoparticles composite using lower-voltage high-resolution TEM. Microscopy (Oxf) 2017; 66:348-355. [PMID: 29016921 DOI: 10.1093/jmicro/dfx021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 05/25/2017] [Indexed: 06/07/2023] Open
Abstract
We have examined the advanced application of transmission electron microscopy (TEM) for the structural characterization of a composite of cellulose nanofiber (CNF) and palladium (Pd) nanoparticles. In the present study, we focused on electron-irradiation damage and optimization of high-resolution TEM imaging of the composite. The investigation indicates that the CNF breaks even under low-electron-dose conditions at an acceleration voltage of 200 kV. We then applied lower-voltage TEM at 60 kV using a spherical aberration corrector and a monochromator, in order to reduce electron-irradiation damage and improve the spatial resolution. The TEM observation achieved high-resolution imaging and revealed the existence of small Pd nanoparticles, around 2 nm in diameter, supported on the CNF. It is considered that the use of a monochromator in combination with spherical aberration correction contributed to the atomic and nanoscale imaging of the composite, owing to the improvement of the information limit under a lower-acceleration voltage.
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Affiliation(s)
- Megumi Ohwada
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Yoshiteru Mizukoshi
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Tomoko Shimokawa
- Center for Advanced Materials, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Noriko Hayashi
- Center for Advanced Materials, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Yuichiro Hayasaka
- The Electron Microscopy Center, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Toyohiko J Konno
- Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
- The Electron Microscopy Center, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
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7
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Ishizuka K, Kimoto K. Why Do We Need to Use Three-Dimensional (3D) Fourier Transform (FT) Analysis to Evaluate a High-Performance Transmission Electron Microscope (TEM)? MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2016; 22:971-980. [PMID: 27786152 DOI: 10.1017/s1431927616011806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The resolution of high-resolution transmission electron microscopes (TEM) has been improved down to subangstrom levels by correcting the spherical aberration (Cs) of the objective lens, and the information limit is thus determined mainly by partial temporal coherence. As a traditional Young's fringe test does not reveal the true information limit for an ultra-high-resolution electron microscope, new methods to evaluate temporal coherence have been proposed based on a tilted-beam diffractogram. However, the diffractogram analysis cannot be applied when the nonlinear contribution becomes significant. Therefore, we have proposed a method based on the three-dimensional (3D) Fourier transform (FT) of through-focus TEM images, and evaluated the performance of some Cs-corrected TEMs at lower voltages. In this report, we generalize the 3D FT analysis and derive the 3D transmission cross-coefficient. The profound difference of the 3D FT analysis from the diffractogram analysis is its capability to extract linear image information from the image intensity, and further to evaluate two linear image contributions separately on the Ewald sphere envelopes. Therefore, contrary to the diffractogram analysis the 3D FT analysis can work with a strong scattering object. This is the necessary condition if we want to directly observe the linear image transfer down to a few tens of picometer.
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Affiliation(s)
- Kazuo Ishizuka
- 1National Institute for Materials Science,1-1 Namiki,Tsukuba,Ibaraki 305-0044,Japan
| | - Koji Kimoto
- 1National Institute for Materials Science,1-1 Namiki,Tsukuba,Ibaraki 305-0044,Japan
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8
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Linck M, Hartel P, Uhlemann S, Kahl F, Müller H, Zach J, Haider M, Niestadt M, Bischoff M, Biskupek J, Lee Z, Lehnert T, Börrnert F, Rose H, Kaiser U. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV. PHYSICAL REVIEW LETTERS 2016; 117:076101. [PMID: 27563976 DOI: 10.1103/physrevlett.117.076101] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Indexed: 06/06/2023]
Abstract
Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.
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Affiliation(s)
- Martin Linck
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Peter Hartel
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Stephan Uhlemann
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Frank Kahl
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Heiko Müller
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Joachim Zach
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Max Haider
- Corrected Electron Optical Systems GmbH, Englerstrasse 28, D-69126 Heidelberg, Germany
| | - Marcel Niestadt
- FEI Company, Achtseweg Noord 5, 5651 GG Eindhoven, Netherlands
| | | | - Johannes Biskupek
- Central facility of electron microscopy, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Zhongbo Lee
- Central facility of electron microscopy, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Tibor Lehnert
- Central facility of electron microscopy, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Felix Börrnert
- Central facility of electron microscopy, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Harald Rose
- Central facility of electron microscopy, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
| | - Ute Kaiser
- Central facility of electron microscopy, Ulm University, Albert-Einstein-Allee 11, D-89081 Ulm, Germany
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9
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Abstract
A few practical aspects of monochromators recently developed for transmission electron microscopy are briefly reviewed. The basic structures and properties of four monochromators, a single Wien filter monochromator, a double Wien filter monochromator, an omega-shaped electrostatic monochromator and an alpha-shaped magnetic monochromator, are outlined. The advantages and side effects of these monochromators in spectroscopy and imaging are pointed out. A few properties of the monochromators in imaging, such as spatial or angular chromaticity, are also discussed.
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Affiliation(s)
- Koji Kimoto
- Electron Microscopy Group, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
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10
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Kimoto K, Sawada H, Sasaki T, Sato Y, Nagai T, Ohwada M, Suenaga K, Ishizuka K. Quantitative evaluation of temporal partial coherence using 3D Fourier transforms of through-focus TEM images. Ultramicroscopy 2013; 134:86-93. [DOI: 10.1016/j.ultramic.2013.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2013] [Revised: 06/08/2013] [Accepted: 06/09/2013] [Indexed: 10/26/2022]
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