Crystallographic and morphological studies of the celestite skeleton of the acantharian species Phyllostaurus siculus

1988 ◽  
Vol 233 (1273) ◽  
pp. 393-405 ◽  
Keyword(s):  
Electron Microscopy ◽  
Biological Control ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Morphological Studies ◽  
Lateral Wing ◽  
Transmission Electron ◽  
Wing Structures ◽  
Cell Centre ◽  
Crystallographic Orientations

The crystallography and morphology of the celestite (SrSO 4 ) skeleton of the acantharian species Phyllostaurus siculus have been studied by electron microscopy, electron diffraction and optical microscopy. The skeleton is composed of 20 spicules, radiating from a central point, which are shown to be divided into three groups according to their morphology. High-resolution transmission electron microscopy (HRTEM) has confirmed the single-crystal nature of each spicule. The spicules connect via lateral wing structures, the crystallographic orientations of which have been determined. The precise arrangement of the spicules has been established and is described in terms of the lateral wing attachments at the cell centre. The effects of crystallographical constraints, efficiency of spicule packing and biological control on spicule arrangement are discussed.

scholarly journals Habits of Magnetosome Crystals in Coccoid Magnetotactic Bacteria

2005 ◽  
Vol 71 (8) ◽  
pp. 4902-4905 ◽  
Author(s):  
Ulysses Lins ◽  
Martha R. McCartney ◽  
Marcos Farina ◽  
Richard B. Frankel ◽  
Peter R. Buseck
Keyword(s):  
Electron Microscopy ◽  
Biological Control ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Magnetotactic Bacteria ◽  
Electron Holography ◽  
Transmission Electron

ABSTRACT High-resolution transmission electron microscopy and electron holography were used to study the habits of exceptionally large magnetite crystals in coccoid magnetotactic bacteria. In addition to the crystal habits, the crystallographic positioning of successive crystals in the magnetosome chain appears to be under strict biological control.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Improved quantification of curvature in high-resolution transmission electron microscopy lattice fringe micrographs of soots

Carbon ◽  
2017 ◽  
Vol 117 ◽  
pp. 174-181 ◽  
Author(s):  
Chang’an Wang ◽  
Thomas Huddle ◽  
Chung-Hsuan Huang ◽  
Wenbo Zhu ◽  
Randy L. Vander Wal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Lattice Fringe ◽  
Transmission Electron

Vertical self-organization of Ge1−xMnx nanocolumn multilayers grown on Ge(001) substrates

2016 ◽  
Vol 30 (20) ◽  
pp. 1650269 ◽  
Author(s):  
Thi Giang Le ◽  
Minh Tuan Dau
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Molecular Beam Epitaxy ◽  
Elastic Constant ◽  
Structural Properties ◽  
Molecular Beam ◽  
Self Organization ◽  
Transmission Electron ◽  
2D Model

High-resolution transmission electron microscopy (HR-TEM) has been used to investigate the structural properties of GeMn/Ge nanocolumns multilayer samples grown on Ge(001) substrates by means of molecular beam epitaxy (MBE) system. Four bilayers with the spacer thickness in the range between 6 nm and 15 nm and 10 periods of bilayers of Ge[Formula: see text]Mn[Formula: see text]/Ge nanocolumn are presented. A simplified 2D model based on the theory of elastic constant interactions has been used to provide reasonable explanations to the vertical self-organization of GeMn nanocolumns in multilayers.

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