Precession of fullerite rotating node at simplest deformations of crystal fragment

2021 ◽  
Author(s):  
Mikhail A. Bubenchikov ◽  
Aleksandr V. Lun-Fu ◽  
Vyacheslav A. Ovchinnikov
Keyword(s):  
Crystal Fragment

LaI2@(18,3)SWNT: The Unprecedented Structure of a LaI2 “Crystal,” Encapsulated within a Single-Walled Carbon Nanotube

2005 ◽  
Vol 11 (5) ◽  
pp. 421-430 ◽  
Author(s):  
Steffi Friedrichs ◽  
Angus I. Kirkland ◽  
Rüdiger R. Meyer ◽  
Jeremy Sloan ◽  
Malcolm L.H. Green
Keyword(s):  
Materials Science ◽  
Imaging Techniques ◽  
Structural Data ◽  
Complete Characterization ◽  
Filling Material ◽  
Single Walled Carbon ◽  
Restoration Technique ◽  
Transmission Electron ◽  
Crystal Fragment ◽  
Walled Carbon Nanotubes

The novel crystallization properties of nano-materials represent a great challenge to researchers across all disciplines of materials science. Simple binary solids can be found to adopt unprecedented structures, when confined into nanometer-sized cavities, such as the inner cylindrical bore of single-walled carbon nanotubes (SWNT). Lanthanum iodide was encapsulated within SWNTs and the resulting encapsulation composite was analyzed using energy-dispersive X-ray microanalysis (EDX) and high-resolution transmission electron microscopy (HRTEM) imaging techniques, to reveal a one-dimensional crystal fragment, with the stoichiometry of LaI2, crystallizing in the structure of LaI3 with one third of the iodine positions unoccupied. A complete characterization of the encapsulation composite was achieved using an enhanced image restoration technique, which restores the object wave from a focal series of HRTEM images, providing information about the precise structural data of both filling material and host SWNT, and thereby enabling the identification of the SWNT chirality.

MgSiO3 perovskite: a HRTEM study

1996 ◽  
Vol 60 (402) ◽  
pp. 799-804
Author(s):  
Ishmael Hassan ◽  
Yasuhiro Kudoh ◽  
Peter R. Buseck ◽  
Eui Ito
Keyword(s):  
X Ray Diffraction ◽  
Phase Boundaries ◽  
Orthorhombic Unit Cell ◽  
X Ray ◽  
Mgsio3 Perovskite ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Cell Dimensions ◽  
Crystal Fragment ◽  
Diffraction Patterns

AbstractSelected-area electron diffraction patterns for the [110] zone of MgSiO3 perovskite are consistent with the orthorhombic unit cell obtained by X-ray diffraction (a = 4.775, b = 4.929, c = 6.897 Å). Various areas of a crystal fragment show diffuse streaking along c*, and well-developed satellite reflections that give a 3-fold repeat along [10]*. Another fragment shows doubled cell dimensions when viewed down [30]. The variable occurrence of the satellite reflectioncs and diffuse streaking indicate subtle variations in ordering, chemistry, or both. Images obtained by high-resolution transmission electron microscopy contain perfectly ordered regions, out-of-phase boundaries, and intergrowths of the two orthorhombic forms of perovskite.

HREM studies of structure, defects and phase transformation in zirconia and Mn stabilised zirconia

1990 ◽  
Vol 48 (4) ◽  
pp. 824-825
Author(s):  
Renu Sharma
Keyword(s):  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Manganese Carbonate ◽  
Image Analysis System ◽  
X Ray Diffraction ◽  
Cubic Form ◽  
Resolution Electron ◽  
On Line ◽  
Crystal Fragment ◽  
Analysis System

Zirconia is known to exist in three different structure types: monoclinic, tetragonal and cubic. Monoclinic is the room temperature form that transforms to tetragonal and finally to cubic at progressively higher temperatures. The monoclinic to tetragonal transformation is reversible, exhibits hysteresis and has been widely studied by thermal analysis, high temperature x-ray diffraction and electron diffraction. This transformation has an undesirable effect on some materials properties. The cubic form of zirconia has been stabilised with yttria, calcia, alumina and magnesia. The decomposition of zirconium carbonate and zirconium manganese carbonate to the respective oxides and their phase tranformation has been studied in situ by electron diffraction and high resolution electron microscopy (HREM) and the results are reported here.The carbonates used in these studies were precipitated from their aqueous solution. Thin crystal fragment were dispersed on holey carbon grids using a suspension in ethanol. A JE0L 4000EX microscope, with double tilt goniometer and on-line Digital MicroVAX II image-analysis system, operating at 400KV, was used for HREM studies.

Synthesis and electrophosphorescence of a novel Iridium(III) complex containing liquid-crystal fragment

2015 ◽  
Vol 30 (5) ◽  
pp. 752-756
Author(s):  
逄 辉 PANG Hui ◽  
郑成武 ZHENG Cheng-wu ◽  
曹建华 CAO Jian-hua ◽  
张 兴 ZHANG Xing ◽  
华瑞茂 HUA Rui-mao
Keyword(s):  
Liquid Crystal ◽  
Crystal Fragment

scholarly journals A New Crystal Form of the SARS-CoV-2 Receptor Binding Domain: CR3022 Complex—An Ideal Target for In-Crystal Fragment Screening of the ACE2 Binding Site Surface

2020 ◽  
Vol 11 ◽  
Author(s):  
Charlie Nichols ◽  
Joseph Ng ◽  
Annika Keshu ◽  
Franca Fraternali ◽  
Gian F. De Nicola
Keyword(s):  
Binding Site ◽  
Receptor Binding ◽  
Chemical Space ◽  
Virus Entry ◽  
Crystal Form ◽  
Binding Domain ◽  
Target Area ◽  
Receptor Binding Domain ◽  
Fragment Screening ◽  
Crystal Fragment

In-crystal fragment screening is a powerful tool to chemically probe the surfaces used by proteins to interact, and identify the chemical space worth exploring to design protein-protein inhibitors. A crucial prerequisite is the identification of a crystal form where the target area is exposed and accessible to be probed by fragments. Here we report a crystal form of the SARS-CoV-2 Receptor Binding Domain in complex with the CR3022 antibody where the ACE2 binding site on the Receptor Binding Domain is exposed and accessible. This crystal form of the complex is a valuable tool to develop antiviral molecules that could act by blocking the virus entry in cells.

scholarly journals Characterisation of a LaI2@(18,3)SWNT encapsulation composite: A 1D LaI2 crystal fragment, adopting the ‘reduced’ structure of LaI3

2003 ◽  
Vol 9 (S02) ◽  
pp. 324-325
Author(s):  
S. Friedrichs ◽  
J. Sloan ◽  
R. R. Meyer ◽  
A. I. Kirkland ◽  
J. L. Hutchison ◽  
...  
Keyword(s):  
Crystal Fragment

scholarly journals Carlhintzeite, Ca2AlF7·H2O, from the Gigante granitic pegmatite, Córdoba province, Argentina: description and crystal structure

2010 ◽  
Vol 74 (4) ◽  
pp. 623-632 ◽  
Author(s):  
A. R. Kampf ◽  
F. Colombo ◽  
J. González del Tánago
Keyword(s):  
Crystal Structure ◽  
Structure Data ◽  
Electron Microprobe ◽  
Empirical Formula ◽  
Direct Methods ◽  
Granitic Pegmatite ◽  
Crystal Fragment

AbstractCarlhintzeite, Ca2AlF7·H2O, has been found at the Gigante pegmatite, Punilla Department, Córdoba Province, Argentina. It occurs as colourless prismatic crystals up to 0.8 mm long, ubiquitously twinned on {001}. Electron microprobe analyses provided the empirical formula Ca1.98Al1.02F6.24(OH)0.76·H1.62O. A crystal fragment used for the collection of structure data provided the triclinic, C1̄ cell: a = 9.4227(4), b = 6.9670(5), c = 9.2671(7) Å, α = 90.974(6), β = 104.802(5), γ = 90.026(6)°, V = 558.08(7) Å3 and Z = 4. The crystal structure, solved by direct methods and refined to R1 = 0.0322 for 723 Fo > 4σF reflections, is made up of linkages of AlF6 octahedra, CaF8 polyhedra and CaF6(H2O)2 polyhedra. The AlF6 octahedra are isolated from one another, but share polyhedral elements with Ca polyhedra. Most notably, the Al1 octahedron shares trans faces with two CaF8 polyhedra and the Al2 octahedron shares trans edges with two CaF6(H2O)2 polyhedra. The linkage of the Ca polyhedra alone can be described as a framework in which edge-sharing chains along b are cross-linked by edge-sharing. Edge-sharing chains of Ca polyhedra along b in the carlhintzeite structure are similar to those along c in the structures of gearksutite, CaAlF4(OH)·(H2O), and prosopite, CaAl2F4(OH)4.

The surprisingly elusive crystal structure of sodium metabisulfite

2004 ◽  
Vol 60 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Kay L. Carter ◽  
Tasneem A. Siddiquee ◽  
Kristen L. Murphy ◽  
Dennis W. Bennett
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Low Temperature ◽  
Unit Cell ◽  
Sodium Metabisulfite ◽  
Asymmetric Unit ◽  
Space Group ◽  
Crystal Fragment ◽  
First Time ◽  
Correct Structure

The crystal structure of Na2S2O5, a simple and common ionic compound, is reported here for the first time. The crystals form non-merohedral twins, with the twin domains related by a twofold axis which bisects the angle between the a and c axes of each unit cell. The structure was determined from a single-crystal fragment of a twinned crystal that had undergone cleavage along the twin boundary. In addition to the problems associated with twinning, space-group determination proved difficult as well, with the structure initially determined in the P21 space group appearing to be disordered with two rotational conformers of the metabisulfite ion occupying equivalent sites in the lattice. An analysis at low temperature provided new weak reflections which were inconsistent with the original unit cell, but indexed to the correct unit cell, allowing for space group and crystal structure determination. The apparent structure, which appeared disordered in P21, seems to have resulted from an apparently fortuitous superposition of two conformationally inequivalent S2O_5^{2-} anions in the asymmetric unit of the correct structure in the P21/n space group. The metabisulfite ions in this structure do not adopt the Cs geometry observed in previously determined crystal structures containing S2O_5^{2-}. The structures of both ions in the asymmetric unit are effectively conformational mirror images of one another with two of the O atoms on each S atom in the ion approaching an eclipsed geometry. This observation provides further evidence that the structures of sulfur-oxy anions in the solid state are dictated mainly by interionic coulombic forces rather than by intraionic bonding interactions

Submarine ‘crystal tuffs’: their origin using a Lower Devonian example from southeastern Australia

1983 ◽  
Vol 120 (5) ◽  
pp. 471-486 ◽  
Author(s):  
R. A. F. Cas
Keyword(s):  
Lower Devonian ◽  
Explosive Eruption ◽  
Fine Sediment ◽  
Pyroclastic Flows ◽  
Minor Components ◽  
Shallow Marine ◽  
Southeastern Australia ◽  
Crystal Fraction ◽  
Crystal Fragment ◽  
Mass Flows

Summary. The submarine crystal-rich volcaniclastics of the Lower Devonian Merrions Tuff contain concentrations of angular to euhedral volcanic quartz, plagioclase and orthoclase. Lithic fragments, largely altered vitriclasts, are minor components and the average matrix content is 37.6%. Associated dacite/andesite and rhyodacitic lavas have average groundmass contents of 64.2%. Rare shards in the graded, pelitic tops of the thick volcaniclastic sedimentation units suggest that the mode of fragmentation originally was by explosive magmatic eruptions. The sedimentology of the volcaniclastics suggests subsequent redeposition by cold-state mass-flow processes. The volcaniclastics form an isotopically coherent suite and so redeposition must have occurred essentially contemporaneously with eruption.The high crystal fragment concentration in these volcaniclastics is higher than lavas and ignimbrites and suggests some process whereby the groundmass fraction of the erupting magma is selectively removed, so concentrating the crystal fraction. The crystal-rich character of the crystal-tuffs is not simply due to explosive eruption. Several primary and secondary factors/processes could have interacted to ultimately produce the crystal-rich character, these being: (i) eruption of highly crystallized magmas (≤ 65% phenocrysts), (ii) concentration of crystals in primary eruption columns, (iii) concentration of crystals in any resulting pyroclastic flows, fine vitric ashes being elutriated out and being carried away in accompanying, trailing ash clouds, (iv) concentration of crystals in secondary eruption columns generated by the flow of hot pyroclastic flows into the ocean, and (v) concentration of crystals by the elutriation of fines into the trailing fine sediment cloud accompanying submarine mass flows resulting from the slumping of volcaniclastic aggregates from shallow marine/subaerial settings.

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