286 results on '"Robinson, Ian K."'
Search Results
252. Vacancy-Driven Noncubic Local Structure and Magnetic Anisotropy Tailoring in FexO-Fe3−δO4 Nanocrystals
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Alexandros Lappas, George Antonaropoulos, Konstantinos Brintakis, Marianna Vasilakaki, Kalliopi N. Trohidou, Vincenzo Iannotti, Giovanni Ausanio, Athanasia Kostopoulou, Milinda Abeykoon, Ian K. Robinson, Emil S. Bozin, Lappas, Alexandro, Antonaropoulos, George, Brintakis, Konstantino, Vasilakaki, Marianna, Trohidou, Kalliopi N., Iannotti, Vincenzo, Ausanio, Giovanni, Kostopoulou, Athanasia, Abeykoon, Milinda, Robinson, Ian K., and Bozin, Emil S.
- Subjects
Condensed Matter Physics, Magnetism, Nanophysics - Abstract
In contrast to bulk materials, nanoscale crystal growth is critically influenced by size- and shape21 dependent properties. However, it is challenging to decipher how stoichiometry, in the realm of mixed22 valence elements, can act to control physical properties, especially when complex bonding is implicated by short- and long-range ordering of structural defects. Here, solution-grown iron-oxide nanocrystals (NCs) of the pilot wüstite system are found to convert into iron-deficient rock-salt and ferro spinel subdomains but attain a surprising tetragonally distorted local structure. Cationic vacancies within chemically uniform NCs are portrayed as the parameter to tweak the underlying properties. These lattice imperfections are shown to produce local exchange-anisotropy fields that reinforce the nanoparticles’ magnetization and overcome the influence of finite-size effects. The concept of atomic-scale defect control in subcritical-size NCs aspires to become a pathway to tailor-made properties with improved performance for hyperthermia heating over defect-free NCs.
- Published
- 2019
253. Polymer Interfaces Analysed on a Nanometer Scale: X-Ray and Neutron Reflectometry
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Stamm, M., Lotsch, H. K. V., editor, Zabel, Hartmut, editor, and Robinson, Ian K., editor
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- 1992
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254. Conference Summary
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Sinha, S. K., Lotsch, H. K. V., editor, Zabel, Hartmut, editor, and Robinson, Ian K., editor
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- 1992
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255. Ultra-Structural Imaging Provides 3D Organization of 46 Chromosomes of a Human Lymphocyte Prophase Nucleus.
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Sajid, Atiqa, Lalani, El-Nasir, Chen, Bo, Hashimoto, Teruo, Griffin, Darren K., Bhartiya, Archana, Thompson, George, Robinson, Ian K., and Yusuf, Mohammed
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HUMAN chromosomes , *CHROMOSOME structure , *CELL nuclei , *THREE-dimensional imaging , *CHROMATIDS , *CELL cycle , *LYMPHOCYTES - Abstract
Three dimensional (3D) ultra-structural imaging is an important tool for unraveling the organizational structure of individual chromosomes at various stages of the cell cycle. Performing hitherto uninvestigated ultra-structural analysis of the human genome at prophase, we used serial block-face scanning electron microscopy (SBFSEM) to understand chromosomal architectural organization within 3D nuclear space. Acquired images allowed us to segment, reconstruct, and extract quantitative 3D structural information about the prophase nucleus and the preserved, intact individual chromosomes within it. Our data demonstrate that each chromosome can be identified with its homolog and classified into respective cytogenetic groups. Thereby, we present the first 3D karyotype built from the compact axial structure seen on the core of all prophase chromosomes. The chromosomes display parallel-aligned sister chromatids with familiar chromosome morphologies with no crossovers. Furthermore, the spatial positions of all 46 chromosomes revealed a pattern showing a gene density-based correlation and a neighborhood map of individual chromosomes based on their relative spatial positioning. A comprehensive picture of 3D chromosomal organization at the nanometer level in a single human lymphocyte cell is presented. [ABSTRACT FROM AUTHOR]
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- 2021
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256. A technique for high-frequency laser-pump X-ray probe experiments at the APS
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Dufresne, Eric M., Adams, Bernhard, Chollet, Matthieu, Harder, Ross, Li, Yuelin, Wen, Haidan, Leake, Steven J., Beitra, Loren, Huang, Xiaojing, and Robinson, Ian K.
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OPTICAL pumping , *LASER beams , *ABSORPTION , *ELECTRIC fields , *STRAINS & stresses (Mechanics) , *SPEED of sound , *FEMTOSECOND lasers , *DIFFRACTION patterns - Abstract
Abstract: When a short-pulse laser beam is absorbed in a crystal, the heat or large electric field can induce time-dependent strain waves which propagate in the material at the speed of sound. At a synchrotron, the repetition rate of the X-ray source (MHz) and the laser (kHz) is often mismatched by several orders of magnitude leading to a very inefficient use of the X-ray probe beam. In this paper, we will show how one can synchronize a femtosecond 88MHz Ti:Sapphire laser to the APS running at the same repetition rate in 324-bunch mode. This efficient use of the X-rays enabled us to measure coherent diffraction patterns from nanoparticle of ZnO as a function of the Bragg angle and time delay between the laser-pump and X-ray probe beams. Significant time-dependent strain can be created with a few nanoJoule per pulse when the nanoparticle is centered in a tight laser focus of a few microns. [Copyright &y& Elsevier]
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- 2011
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257. A single-image retrieval method for edge illumination X-ray phase-contrast imaging: Application and noise analysis
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Ulrich Wagner, Marco Endrizzi, Charlotte K. Hagen, Alberto Bravin, Paul C. Diemoz, Ian K. Robinson, Christoph Rau, Paola Coan, Alessandro Olivo, Fabio A. Vittoria, Diemoz Paul, C, Vittoria Fabio, A, Hagen Charlotte, K, Endrizzi, M, Coan, P, Bravin, A, Wagner Ulrich, H, Rau, C, Robinson Ian, K, and Olivo, A
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Computer science ,Radiography ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Biophysics ,FIS/07 - FISICA APPLICATA (A BENI CULTURALI, AMBIENTALI, BIOLOGIA E MEDICINA) ,General Physics and Astronomy ,Radiation ,Signal-To-Noise Ratio ,01 natural sciences ,Edge illumination ,030218 nuclear medicine & medical imaging ,law.invention ,010309 optics ,03 medical and health sciences ,0302 clinical medicine ,Fast imaging ,law ,Phase-contrast imaging ,0103 physical sciences ,Image Processing, Computer-Assisted ,Radiology, Nuclear Medicine and imaging ,Computer vision ,Lighting ,Phase retrieval ,Data collection ,business.industry ,X-Rays ,General Medicine ,Wood ,Synchrotron ,X-Ray Phase-Contrast Imaging ,Artificial intelligence ,business ,Refractive index ,Synchrotrons - Abstract
Purpose Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has been under development at University College London in recent years, and has shown great potential for both laboratory and synchrotron applications. In this work, we propose a new acquisition and processing scheme. Contrary to existing retrieval methods for EI, which require as input two images acquired in different setup configurations, the proposed approach can retrieve an approximate map of the X-ray phase from a single image, thus significantly simplifying the acquisition procedure and reducing data collection times. Methods The retrieval method is analytically derived, based on the assumption of a quasi-homogeneous object, i.e. an object featuring a constant ratio between refractive index and absorption coefficient. The noise properties of the input and retrieved images are also theoretically analyzed under the developed formalism. The method is applied to experimental synchrotron images of a biological object. Results The experimental results show that the method can provide high-quality images, where the “edge” signal typical of XPCI images is transformed to an “area” contrast that enables an easier interpretation of the sample geometry. Moreover, the retrieved images confirm that the method is highly stable against noise. Conclusions We anticipate that the developed approach will become the method of choice for a variety of applications of EI XPCI, thanks to its ability to simplify the acquisition procedure and reduce acquisitions time and dose to the sample. Future work will focus on the adaptation of the method to computed tomography and to polychromatic radiation from X-ray tubes.
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- 2016
258. 3D lattice distortions and defect structures in ion-implanted nano-crystals.
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Hofmann, Felix, Tarleton, Edmund, Harder, Ross J., Phillips, Nicholas W., Ma, Pui-Wai, Clark, Jesse N., Robinson, Ian K., Abbey, Brian, Liu, Wenjun, and Beck, Christian E.
- Abstract
Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga+), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale revolutionised sample preparation across the life, earth and materials sciences. Despite its widespread usage, detailed understanding of the FIB-induced structural damage, intrinsic to the technique, remains elusive. Here we examine the defects caused by FIB in initially pristine objects. Using Bragg Coherent X-ray Diffraction Imaging (BCDI), we are able to spatially-resolve the full lattice strain tensor in FIB-milled gold nano-crystals. We find that every use of FIB causes large lattice distortions. Even very low ion doses, typical of FIB imaging and previously thought negligible, have a dramatic effect. Our results are consistent with a damage microstructure dominated by vacancies, highlighting the importance of free-surfaces in determining which defects are retained. At larger ion fluences, used during FIB-milling, we observe an extended dislocation network that causes stresses far beyond the bulk tensile strength of gold. These observations provide new fundamental insight into the nature of the damage created and the defects that lead to a surprisingly inhomogeneous morphology. [ABSTRACT FROM AUTHOR]
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- 2017
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259. Correction to: Imaging Light-Induced Migration of Dislocations in Halide Perovskites with 3D Nanoscale Strain Mapping.
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Orr KWP, Diao J, Lintangpradipto MN, Batey DJ, Iqbal AN, Kahmann S, Frohna K, Dubajic M, Zelewski SJ, Dearle AE, Selby TA, Li P, Doherty TAS, Hofmann S, Bakr OM, Robinson IK, and Stranks SD
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- 2024
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260. Strain Heterogeneity and Extended Defects in Halide Perovskite Devices.
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Orr KWP, Diao J, Dey K, Hameed M, Dubajić M, Gilbert HL, Selby TA, Zelewski SJ, Han Y, Fitzsimmons MR, Roose B, Li P, Fan J, Jiang H, Briscoe J, Robinson IK, and Stranks SD
- Abstract
Strain is an important property in halide perovskite semiconductors used for optoelectronic applications because of its ability to influence device efficiency and stability. However, descriptions of strain in these materials are generally limited to bulk averages of bare films, which miss important property-determining heterogeneities that occur on the nanoscale and at interfaces in multilayer device stacks. Here, we present three-dimensional nanoscale strain mapping using Bragg coherent diffraction imaging of individual grains in Cs
0.1 FA0.9 Pb(I0.95 Br0.05 )3 and Cs0.15 FA0.85 SnI3 (FA = formamidinium) halide perovskite absorbers buried in full solar cell devices. We discover large local strains and striking intragrain and grain-to-grain strain heterogeneity, identifying distinct islands of tensile and compressive strain inside grains. Additionally, we directly image dislocations with surprising regularity in Cs0.15 FA0.85 SnI3 grains and find evidence for dislocation-induced antiphase boundary formation. Our results shine a rare light on the nanoscale strains in these materials in their technologically relevant device setting., Competing Interests: The authors declare the following competing financial interest(s): Samuel D. Stranks is a co-founder of Swift Solar., (© 2024 The Authors. Published by American Chemical Society.)- Published
- 2024
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261. Imaging Light-Induced Migration of Dislocations in Halide Perovskites with 3D Nanoscale Strain Mapping.
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Orr KWP, Diao J, Lintangpradipto MN, Batey DJ, Iqbal AN, Kahmann S, Frohna K, Dubajic M, Zelewski SJ, Dearle AE, Selby TA, Li P, Doherty TAS, Hofmann S, Bakr OM, Robinson IK, and Stranks SD
- Abstract
In recent years, halide perovskite materials have been used to make high-performance solar cells and light-emitting devices. However, material defects still limit device performance and stability. Here, synchrotron-based Bragg coherent diffraction imaging is used to visualize nanoscale strain fields, such as those local to defects, in halide perovskite microcrystals. Significant strain heterogeneity within MAPbBr
3 (MA = CH3 NH3 + ) crystals is found in spite of their high optoelectronic quality, and both 〈100〉 and 〈110〉 edge dislocations are identified through analysis of their local strain fields. By imaging these defects and strain fields in situ under continuous illumination, dramatic light-induced dislocation migration across hundreds of nanometers is uncovered. Further, by selectively studying crystals that are damaged by the X-ray beam, large dislocation densities and increased nanoscale strains are correlated with material degradation and substantially altered optoelectronic properties assessed using photoluminescence microscopy measurements. These results demonstrate the dynamic nature of extended defects and strain in halide perovskites, which will have important consequences for device performance and operational stability., (© 2023 The Authors. Advanced Materials published by Wiley-VCH GmbH.)- Published
- 2023
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262. Emergence of liquid following laser melting of gold thin films.
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Robinson IK, Griffiths JP, Koch R, Assefa TA, Suzana AF, Cao Y, Kim S, Kim D, Lee H, Kim S, Lee JH, Park SY, Eom I, Park J, Nam D, Kim S, Chun SH, Hyun H, Kim KS, Lu M, Song C, Kim H, Billinge SJL, and Bozin ES
- Abstract
X-ray structural science is undergoing a revolution driven by the emergence of X-ray Free-electron Laser (XFEL) facilities. The structures of crystalline solids can now be studied on the picosecond time scale relevant to phonons, atomic vibrations which travel at acoustic velocities. In the work presented here, X-ray diffuse scattering is employed to characterize the time dependence of the liquid phase emerging from femtosecond laser-induced melting of polycrystalline gold thin films using an XFEL. In a previous analysis of Bragg peak profiles, we showed the supersonic disappearance of the solid phase and presented a model of pumped hot electrons carrying energy from the gold surface to scatter at internal grain boundaries. This generates melt fronts propagating relatively slowly into the crystal grains. By conversion of diffuse scattering to a partial X-ray pair distribution function, we demonstrate that it has the characteristic shape obtained by Fourier transformation of the measured F(Q). The diffuse signal fraction increases with a characteristic rise-time of 13 ps, roughly independent of the incident pump fluence and consequent final liquid fraction. This suggests the role of further melt-front nucleation processes beyond grain boundaries., (open access.)
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- 2023
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263. Verwey transition as evolution from electronic nematicity to trimerons via electron-phonon coupling.
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Wang W, Li J, Liang Z, Wu L, Lozano PM, Komarek AC, Shen X, Reid AH, Wang X, Li Q, Yin W, Sun K, Robinson IK, Zhu Y, Dean MPM, and Tao J
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- Cold Temperature, Electronics, Entropy, Electrons, Phonons
- Abstract
Understanding the driving mechanisms behind metal-insulator transitions (MITs) is a critical step toward controlling material's properties. Since the proposal of charge order-induced MIT in magnetite Fe
3 O4 in 1939 by Verwey, the nature of the charge order and its role in the transition have remained elusive. Recently, a trimeron order was found in the low-temperature structure of Fe3 O4 ; however, the expected transition entropy change in forming trimeron is greater than the observed value, which arises a reexamination of the ground state in the high-temperature phase. Here, we use electron diffraction to unveil that a nematic charge order on particular Fe sites emerges in the high-temperature structure of bulk Fe3 O4 and that, upon cooling, a competitive intertwining of charge and lattice orders arouses the Verwey transition. Our findings discover an unconventional type of electronic nematicity in correlated materials and offer innovative insights into the transition mechanism in Fe3 O4 via the electron-phonon coupling.- Published
- 2023
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264. Real-space observation of fluctuating antiferromagnetic domains.
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Kim MG, Barbour A, Hu W, Wilkins SB, Robinson IK, Dean MPM, Yang J, Won C, Cheong SW, Mazzoli C, and Kiryukhin V
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Magnetic domains play a fundamental role in physics of magnetism and its technological applications. Dynamics of antiferromagnetic domains is poorly understood, although antiferromagnets are expected to be extensively used in future electronic devices wherein it determines the stability and operational speed. Dynamics of antiferromagnets also features prominently in the studies of topological quantum matter. Real-space imaging of fluctuating antiferromagnetic domains is therefore highly desired but has never been demonstrated. We use coherent x-ray diffraction to obtain videos of fluctuating micrometer-scale antiferromagnetic domains in Ni
2 MnTeO6 on time scales from 10-1 to 103 s. In the collinear phase, thermally activated domain wall motion is observed in the vicinity of the Néel temperature. Unexpectedly, the fluctuations persist through the full range of the higher-temperature helical phase. These observations illustrate the high potential significance of the dynamic domain imaging in phase transition studies and in magnetic device research.- Published
- 2022
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265. Multiscale Understanding of Surface Structural Effects on High-Temperature Operational Resiliency of Layered Oxide Cathodes.
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Liu X, Zhou X, Liu Q, Diao J, Zhao C, Li L, Liu Y, Xu W, Daali A, Harder R, Robinson IK, Dahbi M, Alami J, Chen G, Xu GL, and Amine K
- Abstract
The worldwide energy demand in electric vehicles and the increasing global temperature have called for development of high-energy and long-life lithium-ion batteries (LIBs) with improved high-temperature operational resiliency. However, current attention has been mostly focused on cycling aging at elevated temperature, leaving considerable gaps of knowledge in the failure mechanism, and practical control of abusive calendar aging and thermal runaway that are highly related to the eventual operational lifetime and safety performance of LIBs. Herein, using a combination of various in situ synchrotron X-ray and electron microscopy techniques, a multiscale understanding of surface structure effects involved in regulating the high-temperature operational tolerance of polycrystalline Ni-rich layered cathodes is reported. The results collectively show that an ultraconformal poly(3,4-ethylenedioxythiophene) coating can effectively prevent a LiNi
0.8 Co0.1 Mn0.1 O2 cathode from undergoing undesired phase transformation and transition metal dissolution on the surface, atomic displacement, and dislocations within primary particles, intergranular cracking along the grain boundaries within secondary particles, and intensive bulk oxygen release during high state-of-charge and high-temperature aging. The present work highlights the essential role of surface structure controls in overcoming the multiscale degradation pathways of high-energy battery materials at extreme temperature., (© 2021 Wiley-VCH GmbH.)- Published
- 2022
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266. Real Space Imaging of Spin Stripe Domain Fluctuations in a Complex Oxide.
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Wu L, Shen Y, Barbour AM, Wang W, Prabhakaran D, Boothroyd AT, Mazzoli C, Tranquada JM, Dean MPM, and Robinson IK
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Understanding the formation and dynamics of charge and spin-ordered states in low-dimensional transition metal oxide materials is crucial to understanding unconventional high-temperature superconductivity. La_{2-x}Sr_{x}NiO_{4+δ} (LSNO) has attracted much attention due to its interesting spin dynamics. Recent x-ray photon correlation spectroscopy studies have revealed slow dynamics of the spin order (SO) stripes in LSNO. Here, we applied resonant soft x-ray ptychography to map the spatial distribution of the SO stripe domain inhomogeneity in real space. The reconstructed images show the SO domains are spatially anisotropic, in agreement with previous diffraction studies. For the SO stripe domains, it is found that the correlation lengths along different directions are strongly coupled in space. Surprisingly, fluctuations were observed in the real space amplitude signal, rather than the phase or position. We attribute the observed slow dynamics of the stripe domains in LSNO to thermal fluctuations of the SO domain boundaries.
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- 2021
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267. Correction to: X-ray ptychography imaging of human chromosomes after low-dose irradiation.
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Bhartiya A, Batey D, Cipiccia S, Shi X, Rau C, Botchway S, Yusuf M, and Robinson IK
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- 2021
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268. Quantitative phase measurements of human cell nuclei using X-ray ptychography.
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Schwenke J, Yusuf M, Shemilt LA, Wagner U, Sajid A, Morrison GR, Zhang F, Parsons A, Rau C, and Robinson IK
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- Algorithms, Humans, Image Processing, Computer-Assisted methods, Synchrotrons, X-Ray Diffraction, X-Rays, Cell Nucleus ultrastructure, Microscopy, Phase-Contrast methods
- Abstract
The human cell nucleus serves as an important organelle holding the genetic blueprint for life. In this work, X-ray ptychography was applied to assess the masses of human cell nuclei using its unique phase shift information. Measurements were carried out at the I13-1 beamline at the Diamond Light Source that has extremely large transverse coherence properties. The ptychographic diffractive imaging approach allowed imaging of large structures that gave quantitative measurements of the phase shift in 2D projections. In this paper a modified ptychography algorithm that improves the quality of the reconstruction for weak scattering samples is presented. The application of this approach to calculate the mass of several human nuclei is also demonstrated.
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- 2021
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269. Laser-induced transient magnons in Sr 3 Ir 2 O 7 throughout the Brillouin zone.
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Mazzone DG, Meyers D, Cao Y, Vale JG, Dashwood CD, Shi Y, James AJA, Robinson NJ, Lin J, Thampy V, Tanaka Y, Johnson AS, Miao H, Wang R, Assefa TA, Kim J, Casa D, Mankowsky R, Zhu D, Alonso-Mori R, Song S, Yavas H, Katayama T, Yabashi M, Kubota Y, Owada S, Liu J, Yang J, Konik RM, Robinson IK, Hill JP, McMorrow DF, Först M, Wall S, Liu X, and Dean MPM
- Abstract
Although ultrafast manipulation of magnetism holds great promise for new physical phenomena and applications, targeting specific states is held back by our limited understanding of how magnetic correlations evolve on ultrafast timescales. Using ultrafast resonant inelastic X-ray scattering we demonstrate that femtosecond laser pulses can excite transient magnons at large wavevectors in gapped antiferromagnets and that they persist for several picoseconds, which is opposite to what is observed in nearly gapless magnets. Our work suggests that materials with isotropic magnetic interactions are preferred to achieve rapid manipulation of magnetism., Competing Interests: The authors declare no competing interest.
- Published
- 2021
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270. Structure of a seeded palladium nanoparticle and its dynamics during the hydride phase transformation.
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Suzana AF, Wu L, Assefa TA, Williams BP, Harder R, Cha W, Kuo CH, Tsung CK, and Robinson IK
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Palladium absorbs large volumetric quantities of hydrogen at room temperature and ambient pressure, making the palladium hydride system a promising candidate for hydrogen storage. Here, we use Bragg coherent diffraction imaging to map the strain associated with defects in three dimensions before and during the hydride phase transformation of an individual octahedral palladium nanoparticle, synthesized using a seed-mediated approach. The displacement distribution imaging unveils the location of the seed nanoparticle in the final nanocrystal. By comparing our experimental results with a finite-element model, we verify that the seed nanoparticle causes a characteristic displacement distribution of the larger nanocrystal. During the hydrogen exposure, the hydride phase is predominantly formed on one tip of the octahedra, where there is a high number of lower coordinated Pd atoms. Our experimental and theoretical results provide an unambiguous method for future structure optimization of seed-mediated nanoparticle growth and in the design of palladium-based hydrogen storage systems., (© 2021. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)
- Published
- 2021
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271. X-ray Ptychography Imaging of Human Chromosomes After Low-dose Irradiation.
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Bhartiya A, Batey D, Cipiccia S, Shi X, Rau C, Botchway S, Yusuf M, and Robinson IK
- Subjects
- Humans, Karyotyping, X-Rays, Chromosomes, Human, Synchrotrons
- Abstract
Studies of the structural and functional role of chromosomes in cytogenetics have spanned more than 10 decades. In this work, we take advantage of the coherent X-rays available at the latest synchrotron sources to extract the individual masses of all 46 chromosomes of metaphase human B and T cells using hard X-ray ptychography. We have produced 'X-ray karyotypes' of both heavy metal-stained and unstained spreads to determine the gain or loss of genetic material upon low-level X-ray irradiation doses due to radiation damage. The experiments were performed at the I-13 beamline, Diamond Light Source, Didcot, UK, using the phase-sensitive X-ray ptychography method.
- Published
- 2021
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272. Multimodal Imaging of Autofluorescent Sites Reveals Varied Chemical Speciation in SSZ-13 Crystals.
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Omori N, Candeo A, Mosca S, Lezcano-Gonzalez I, Robinson IK, Li L, Greenaway AG, Collier P, and Beale AM
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A multimodal imaging study of chabazite is used to show the distribution of and discriminate between different emissive deposits arising as a result of the detemplation process. Confocal imaging, 3D fluorescence lifetime imaging, 3D multispectral fluorescence imaging, and Raman mapping are used to show three different types of emissive behaviours each characterised by different spatial distributions, trends in lifetime, spectral signals, and Raman signatures. A notable difference is seen in the morphology of agglomerated surface deposits and larger subsurface deposits, which experience lifetime augmentation due to spatial confinement. The distribution of organic residue throughout the crystal volume is comparable to XRF mapping that shows Si enrichment on the outer edges and higher Al content through the centre, demonstrating that a fluorescence-based technique can also be used to indirectly comment on the compositional chemistry of the inorganic framework., (© 2020 Wiley-VCH GmbH.)
- Published
- 2021
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273. Operando Bragg Coherent Diffraction Imaging of LiNi 0.8 Mn 0.1 Co 0.1 O 2 Primary Particles within Commercially Printed NMC811 Electrode Sheets.
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Estandarte AKC, Diao J, Llewellyn AV, Jnawali A, Heenan TMM, Daemi SR, Bailey JJ, Cipiccia S, Batey D, Shi X, Rau C, Brett DJL, Jervis R, Robinson IK, and Shearing PR
- Abstract
Due to complex degradation mechanisms, disparities between the theoretical and practical capacities of lithium-ion battery cathode materials persist. Specifically, Ni-rich chemistries such as LiNi
0.8 Mn0.1 Co0.1 O2 (or NMC811) are one of the most promising choices for automotive applications; however, they continue to suffer severe degradation during operation that is poorly understood, thus challenging to mitigate. Here we use operando Bragg coherent diffraction imaging for 4D analysis of these mechanisms by inspecting the individual crystals within primary particles at various states of charge (SoC). Although some crystals were relatively homogeneous, we consistently observed non-uniform distributions of inter- and intracrystal strain at all measured SoC. Pristine structures may already possess heterogeneities capable of triggering crystal splitting and subsequently particle cracking. During low-voltage charging (2.7-3.5 V), crystal splitting may still occur even during minimal bulk deintercalation activity; and during discharging, rotational effects within parallel domains appear to be the precursor for the nucleation of screw dislocations at the crystal core. Ultimately, this discovery of the central role of crystal grain splitting in the charge/discharge dynamics may have ramifications across length scales that affect macroscopic performance loss during real-world battery operation.- Published
- 2021
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274. Time-resolved in situ visualization of the structural response of zeolites during catalysis.
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Kang J, Carnis J, Kim D, Chung M, Kim J, Yun K, An G, Cha W, Harder R, Song S, Sikorski M, Robert A, Thanh NH, Lee H, Choi YN, Huang X, Chu YS, Clark JN, Song MK, Yoon KB, Robinson IK, and Kim H
- Abstract
Zeolites are three-dimensional aluminosilicates having unique properties from the size and connectivity of their sub-nanometer pores, the Si/Al ratio of the anionic framework, and the charge-balancing cations. The inhomogeneous distribution of the cations affects their catalytic performances because it influences the intra-crystalline diffusion rates of the reactants and products. However, the structural deformation regarding inhomogeneous active regions during the catalysis is not yet observed by conventional analytical tools. Here we employ in situ X-ray free electron laser-based time-resolved coherent X-ray diffraction imaging to investigate the internal deformations originating from the inhomogeneous Cu ion distributions in Cu-exchanged ZSM-5 zeolite crystals during the deoxygenation of nitrogen oxides with propene. We show that the interactions between the reactants and the active sites lead to an unusual strain distribution, confirmed by density functional theory simulations. These observations provide insights into the role of structural inhomogeneity in zeolites during catalysis and will assist the future design of zeolites for their applications.
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- 2020
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275. Complete Strain Mapping of Nanosheets of Tantalum Disulfide.
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Cao Y, Assefa T, Banerjee S, Wieteska A, Zi-Ren Wang D, Pasupathy A, Tong X, Liu Y, Lu W, Sun YP, He Y, Huang X, Yan H, Chu YS, Billinge SJL, and Robinson IK
- Abstract
Quasi-two-dimensional (quasi-2D) materials hold promise for future electronics because of their unique band structures that result in electronic and mechanical properties sensitive to crystal strains in all three dimensions. Quantifying crystal strain is a prerequisite to correlating it with the performance of the device and calls for high resolution but spatially resolved rapid characterization methods. Here, we show that using fly-scan nano X-ray diffraction, we can accomplish a tensile strain sensitivity below 0.001% with a spatial resolution of better than 80 nm over a spatial extent of 100 μm on quasi-2D flakes of 1T-TaS
2 . Coherent diffraction patterns were collected from a ∼100 nm thick sheet of 1T-TaS2 by scanning a 12 keV focused X-ray beam across and rotating the sample. We demonstrate that the strain distribution around micron- and submicron-sized "bubbles" that are present in the sample may be reconstructed from these images. The experiments use state-of-the-art synchrotron instrumentation and will allow rapid and nonintrusive strain mapping of thin-film samples and electronic devices based on quasi-2D materials.- Published
- 2020
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276. Ultrafast x-ray diffraction study of melt-front dynamics in polycrystalline thin films.
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Assefa TA, Cao Y, Banerjee S, Kim S, Kim D, Lee H, Kim S, Lee JH, Park SY, Eom I, Park J, Nam D, Kim S, Chun SH, Hyun H, Kim KS, Juhas P, Bozin ES, Lu M, Song C, Kim H, Billinge SJL, and Robinson IK
- Abstract
Melting is a fundamental process of matter that is still not fully understood at the microscopic level. Here, we use time-resolved x-ray diffraction to examine the ultrafast melting of polycrystalline gold thin films using an optical laser pump followed by a delayed hard x-ray probe pulse. We observe the formation of an intermediate new diffraction peak, which we attribute to material trapped between the solid and melted states, that forms 50 ps after laser excitation and persists beyond 500 ps. The peak width grows rapidly for 50 ps and then narrows distinctly at longer time scales. We attribute this to a melting band originating from the grain boundaries and propagating into the grains. Our observation of this intermediate state has implications for the use of ultrafast lasers for ablation during pulsed laser deposition., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).)
- Published
- 2020
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277. Super-Resolution Microscopy Reveals Shape and Distribution of Dislocations in Single-Crystal Nanocomposites.
- Author
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Ihli J, Green DC, Lynch C, Holden MA, Lee PA, Zhang S, Robinson IK, Webb SED, and Meldrum FC
- Abstract
With their potential to offer new properties, single crystals containing nanoparticles provide an attractive class of nanocomposite materials. However, to fully profit from these, it is essential that we can characterise their 3D structures, identifying the locations of individual nanoparticles, and the defects present within the host crystals. Using calcite crystals containing quantum dots as a model system, we here use 3D stochastic optical reconstruction microscopy (STORM) to locate the positions of the nanoparticles within the host crystal. The nanoparticles are shown to preferentially associate with dislocations in a manner previously recognised for atomic impurities, rendering these defects visible by STORM. Our images also demonstrate that the types of dislocations formed at the crystal/substrate interface vary according to the nucleation face, and dislocation loops are observed that have entirely different geometries to classic misfit dislocations. This approach offers a rapid, easily accessed, and non-destructive method for visualising the dislocations present within crystals, and gives insight into the mechanisms by which additives become occluded within crystals., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2019
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278. Resolving 500 nm axial separation by multi-slice X-ray ptychography.
- Author
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Huang X, Yan H, He Y, Ge M, Öztürk H, Fang YLL, Ha S, Lin M, Lu M, Nazaretski E, Robinson IK, and Chu YS
- Abstract
Multi-slice X-ray ptychography offers an approach to achieve images with a nanometre-scale resolution from samples with thicknesses larger than the depth of field of the imaging system by modeling a thick sample as a set of thin slices and accounting for the wavefront propagation effects within the specimen. Here, we present an experimental demonstration that resolves two layers of nanostructures separated by 500 nm along the axial direction, with sub-10 nm and sub-20 nm resolutions on two layers, respectively. Fluorescence maps are simultaneously measured in the multi-modality imaging scheme to assist in decoupling the mixture of low-spatial-frequency features across different slices. The enhanced axial sectioning capability using correlative signals obtained from multi-modality measurements demonstrates the great potential of the multi-slice ptychography method for investigating specimens with extended dimensions in 3D with high resolution., (open access.)
- Published
- 2019
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279. Extending the depth of field for ptychography using complex-valued wavelets: publisher's note.
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Huang X, Yan H, Robinson IK, and Chu YS
- Abstract
This publisher's note corrects an error in Eq. (3) of Opt. Lett.44, 503 (2019).OPLEDP0146-959210.1364/OL.44.000503.
- Published
- 2019
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280. Visualization of the effect of additives on the nanostructures of individual bio-inspired calcite crystals.
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Ihli J, Clark JN, Kanwal N, Kim YY, Holden MA, Harder RJ, Tang CC, Ashbrook SE, Robinson IK, and Meldrum FC
- Abstract
Soluble additives provide a versatile strategy for controlling crystallization processes, enabling selection of properties including crystal sizes, morphologies, and structures. The additive species can also be incorporated within the crystal lattice, leading for example to enhanced mechanical properties. However, while many techniques are available for analyzing particle shape and structure, it remains challenging to characterize the structural inhomogeneities and defects introduced into individual crystals by these additives, where these govern many important material properties. Here, we exploit Bragg coherent diffraction imaging to visualize the effects of soluble additives on the internal structures of individual crystals on the nanoscale. Investigation of bio-inspired calcite crystals grown in the presence of lysine or magnesium ions reveals that while a single dislocation is observed in calcite crystals grown in the presence of lysine, magnesium ions generate complex strain patterns. Indeed, in addition to the expected homogeneous solid solution of Mg ions in the calcite lattice, we observe two zones comprising alternating lattice contractions and relaxation, where comparable alternating layers of high magnesium calcite have been observed in many magnesium calcite biominerals. Such insight into the structures of nanocomposite crystals will ultimately enable us to understand and control their properties.
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- 2018
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281. 3D X-Ray Nanotomography of Cells Grown on Electrospun Scaffolds.
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Bradley RS, Robinson IK, and Yusuf M
- Subjects
- Cell Proliferation, Humans, Imaging, Three-Dimensional, X-Rays, Fibroblasts cytology, Nanotechnology methods, Tissue Engineering methods, Tissue Scaffolds chemistry
- Abstract
Here, it is demonstrated that X-ray nanotomography with Zernike phase contrast can be used for 3D imaging of cells grown on electrospun polymer scaffolds. The scaffold fibers and cells are simultaneously imaged, enabling the influence of scaffold architecture on cell location and morphology to be studied. The high resolution enables subcellular details to be revealed. The X-ray imaging conditions were optimized to reduce scan times, making it feasible to scan multiple regions of interest in relatively large samples. An image processing procedure is presented which enables scaffold characteristics and cell location to be quantified. The procedure is demonstrated by comparing the ingrowth of cells after culture for 3 and 6 days., (© 2016 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2017
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282. A single-image retrieval method for edge illumination X-ray phase-contrast imaging: Application and noise analysis.
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Diémoz PC, Vittoria FA, Hagen CK, Endrizzi M, Coan P, Bravin A, Wagner UH, Rau C, Robinson IK, and Olivo A
- Subjects
- Image Processing, Computer-Assisted, Synchrotrons, Wood, X-Rays, Lighting, Radiography instrumentation, Signal-To-Noise Ratio
- Abstract
Purpose: Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has been under development at University College London in recent years, and has shown great potential for both laboratory and synchrotron applications. In this work, we propose a new acquisition and processing scheme. Contrary to existing retrieval methods for EI, which require as input two images acquired in different setup configurations, the proposed approach can retrieve an approximate map of the X-ray phase from a single image, thus significantly simplifying the acquisition procedure and reducing data collection times., Methods: The retrieval method is analytically derived, based on the assumption of a quasi-homogeneous object, i.e. an object featuring a constant ratio between refractive index and absorption coefficient. The noise properties of the input and retrieved images are also theoretically analyzed under the developed formalism. The method is applied to experimental synchrotron images of a biological object., Results: The experimental results show that the method can provide high-quality images, where the "edge" signal typical of XPCI images is transformed to an "area" contrast that enables an easier interpretation of the sample geometry. Moreover, the retrieved images confirm that the method is highly stable against noise., Conclusions: We anticipate that the developed approach will become the method of choice for a variety of applications of EI XPCI, thanks to its ability to simplify the acquisition procedure and reduce acquisitions time and dose to the sample. Future work will focus on the adaptation of the method to computed tomography and to polychromatic radiation from X-ray tubes., (Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)
- Published
- 2016
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283. Phase retrieval by coherent modulation imaging.
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Zhang F, Chen B, Morrison GR, Vila-Comamala J, Guizar-Sicairos M, and Robinson IK
- Abstract
Phase retrieval is a long-standing problem in imaging when only the intensity of the wavefield can be recorded. Coherent diffraction imaging is a lensless technique that uses iterative algorithms to recover amplitude and phase contrast images from diffraction intensity data. For general samples, phase retrieval from a single-diffraction pattern has been an algorithmic and experimental challenge. Here we report a method of phase retrieval that uses a known modulation of the sample exit wave. This coherent modulation imaging method removes inherent ambiguities of coherent diffraction imaging and uses a reliable, rapidly converging iterative algorithm involving three planes. It works for extended samples, does not require tight support for convergence and relaxes dynamic range requirements on the detector. Coherent modulation imaging provides a robust method for imaging in materials and biological science, while its single-shot capability will benefit the investigation of dynamical processes with pulsed sources, such as X-ray free-electron lasers.
- Published
- 2016
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284. Beyond crystallography: diffractive imaging using coherent x-ray light sources.
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Miao J, Ishikawa T, Robinson IK, and Murnane MM
- Abstract
X-ray crystallography has been central to the development of many fields of science over the past century. It has now matured to a point that as long as good-quality crystals are available, their atomic structure can be routinely determined in three dimensions. However, many samples in physics, chemistry, materials science, nanoscience, geology, and biology are noncrystalline, and thus their three-dimensional structures are not accessible by traditional x-ray crystallography. Overcoming this hurdle has required the development of new coherent imaging methods to harness new coherent x-ray light sources. Here we review the revolutionary advances that are transforming x-ray sources and imaging in the 21st century., (Copyright © 2015, American Association for the Advancement of Science.)
- Published
- 2015
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285. Evaluation of partial coherence correction in X-ray ptychography.
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Burdet N, Shi X, Parks D, Clark JN, Huang X, Kevan SD, and Robinson IK
- Abstract
Coherent X-ray Diffraction Imaging (CDI) and X-ray ptychography both heavily rely on the high degree of spatial coherence of the X-ray illumination for sufficient experimental data quality for reconstruction convergence. Nevertheless, the majority of the available synchrotron undulator sources have a limited degree of partial coherence, leading to reduced data quality and a lower speckle contrast in the coherent diffraction patterns. It is still an open question whether experimentalists should compromise the coherence properties of an X-ray source in exchange for a higher flux density at a sample, especially when some materials of scientific interest are relatively weak scatterers. A previous study has suggested that in CDI, the best strategy for the study of strong phase objects is to maintain a high degree of coherence of the illuminating X-rays because of the broadening of solution space resulting from the strong phase structures. In this article, we demonstrate the first systematic analysis of the effectiveness of partial coherence correction in ptychography as a function of the coherence properties, degree of complexity of illumination (degree of phase diversity of the probe) and sample phase complexity. We have also performed analysis of how well ptychographic algorithms refine X-ray probe and complex coherence functions when those variables are unknown at the start of reconstructions, for noise-free simulated data, in the case of both real-valued and highly-complex objects.
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- 2015
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286. Coherent x-ray imaging of collagen fibril distributions within intact tendons.
- Author
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Berenguer F, Bean RJ, Bozec L, Vila-Comamala J, Zhang F, Kewish CM, Bunk O, Rodenburg JM, and Robinson IK
- Subjects
- Algorithms, Animals, Image Processing, Computer-Assisted, Rats, X-Ray Diffraction, X-Rays, Fibrillar Collagens metabolism, Molecular Imaging methods, Tendons metabolism
- Abstract
The characterization of the structure of highly hierarchical biosamples such as collagen-based tissues at the scale of tens of nanometers is essential to correlate the tissue structure with its growth processes. Coherent x-ray Bragg ptychography is an innovative imaging technique that gives high resolution images of the ordered parts of such samples. Herein, we report how we used this method to image the collagen fibrillar ultrastructure of intact rat tail tendons. The images show ordered fibrils extending over 10-20 μm in length, with a quantifiable D-banding spacing variation of 0.2%. Occasional defects in the fibrils distribution have also been observed, likely indicating fibrillar fusion events., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2014
- Full Text
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