The identification of magnetic minerals and other selfassembled structures within magnetotactic bacteria using Electron Microscopy and related micro-techniques

1992 ◽  
Vol 50 (2) ◽  
pp. 1022-1023
Author(s):  
Dennis A. Bazylinski ◽  
Anthony J. Garratt-Reed ◽  
Richard B. Frankel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Behavior ◽  
Magnetotactic Bacteria ◽  
Structural Features ◽  
Magnetic Minerals ◽  
Intracellular Iron ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Transmission

Magnetotactic bacteria are a diverse group of procaryotes whose direction of motility is influenced by magnetic fields. These organisms are ubiquitous in aquatic habitats and contain unique intracellular iron-rich membrane-bounded inclusions called magnetosomes that are responsible for the cells’ magnetic behavior. The composition, size (40-100 nm), morphology, position, and orientation of the particles appear to be highly controlled by these bacteria. Ferrimagnetic magnetite (Fe3O4), greigite (Fe3S4), and pyrrhotite (Fe7S8) and nonmagnetic pyrite (FeS2) have been identified as the mineral phases of the magnetosomes in different bacteria. These organisms also contain other intracellular structures that reflect aspects of their physiology, metabolism, and ecology. In order to determine the external structural features of cells and the composition and structure of their intracellular inclusions, transmission electron microscopy (TEM), scanning-transmission electron microscopy (STEM), energy-dispersive x-ray detection (EDXA), and selected area electron diffraction (SAED) techniques were employed.The results of a typical electron microscope (EM) and microanalytical study of a Fe3O4-producing magnetotactic bacterium is shown in Figures 1-4. This unidentified organism, designated strain MV-4, was isolated from sulfide-rich water and sediment collected from a salt marsh.

Template-Assisted Fabrication of Double-Shelled Nanotubes Composed of Inner Shell Pb(Zr0.52Ti0.48)O3 and Outer Shell TiO2 by Sol-Gel Process with Spin-Coating Technique

2011 ◽  
Vol 1292 ◽  
Author(s):  
Y. C. Choi ◽  
S. Y. Cho ◽  
S. D. Bu
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spin Coating ◽  
Sol Gel ◽  
Outer Shell ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Scanning Transmission ◽  
Diffraction Patterns

ABSTRACTDouble-shelled nanotubes composed of inner shell Pb(Zr0.52Ti0.48)O3 (PZT) and outer shell TiO2 are successfully fabricated by a spin coating of each sol-gel solution on porous anodic alumina template. Field emission transmission electron microscopy images show that they have a ~ 10 nm wall thickness. The selected area electron diffraction patterns show that they have two mixed crystalline phases of tetragonal PZT and anatase TiO2. The analyses of scanning transmission electron microscopy equipped with energy dispersive X-ray spectroscopy confirm their uniform distribution of each element.

Synthesis of CuO and Cu2O crystalline nanowires using Cu(OH)2 nanowire templates

2003 ◽  
Vol 18 (12) ◽  
pp. 2756-2759 ◽  
Author(s):  
Wenzhong Wang ◽  
Oomman K. Varghese ◽  
Chuanmin Ruan ◽  
Maggie Paulose ◽  
Craig A. Grimes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Average Diameter ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron

Crystalline CuO and Cu2O nanowires with an average diameter of about 10 nm and lengths of several tens of microns were successfully synthesized, depending on synthesis conditions, using precursor Cu(OH)2 nanowires as templates. The crystallinity, purity, morphology, and structural features of the as-prepared nanowires were characterized by powder x-ray diffraction, selected-area electron diffraction, and high-resolution transmission electron microscopy. The results showed that the precursor polycrystalline Cu(OH)2 nanowires served as both reactants for the growth of CuO and Cu2O nanowires, and as templates controlling the size and shape of the resulting nanowires.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Magnesium and sulfur in mast cell and basophil granules of lower vertebrates in relation with histamine

1992 ◽  
Vol 50 (2) ◽  
pp. 1596-1597
Author(s):  
Kenichi Takaya
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Mast Cell ◽  
Mast Cells ◽  
Tree Frog ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Fresh Frozen ◽  
Ultrathin Sections

Mast cell and basophil granules of the vertebrate contain heparin or related sulfated proteoglycans. Histamine is also present in mammalian mast cells and basophils. However, no histamine is detected in mast cell granules of the amphibian or fish, while it is shown in those of reptiles and birds A quantitative x-ray microanalysis of mast cell granules of fresh frozen dried ultrathin sections of the tongue of Wistar rats and tree frogs disclosed high concentrations of sulfur in rat mast cell granules and those of sulfur and magnesium in the tree frog granules. Their concentrations in tree frog mast cell granules were closely correlated (r=0.94).Fresh frozen dried ultrathin sections and fresh air-dried prints of the tree frog tongue and spleen and young red-eared turtle (ca. 6 g) spleen and heart blood were examined by a quantitative energy-dispersive x-ray microanalysis (X-650, Kevex-7000) for the element constituents of the granules of mast cells and basophils. The specimens were observed by transmission electron microscopy (TEM) (80-200 kV) and followed by scanning transmission electron microscopy (STEM) under an analytical electron microscope (X-650) at an acceleration voltage of 40 kV and a specimen current of 0.2 nA. A spot analysis was performed in a STEM mode for 100 s at a specimen current of 2 nA on the mast cell and basophil granules and other areas of the cells. Histamine was examined by the o-phthalaldehyde method.

Scanning Transmission Electron Microscopy of Polyethylene Crystals

1980 ◽  
Vol 38 ◽  
pp. 242-245
Author(s):  
F. Khoury ◽  
L. H. Bolz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallization Temperature ◽  
Scanning Transmission Electron Microscopy ◽  
Growth Habit ◽  
Lateral Growth ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Growth Habits

The lateral growth habits and non-planar conformations of polyethylene crystals grown from dilute solutions (<0.1% wt./vol.) are known to vary depending on the crystallization temperature.1-3 With the notable exception of a study by Keith2, most previous studies have been limited to crystals grown at <95°C. The trend in the change of the lateral growth habit of the crystals with increasing crystallization temperature (other factors remaining equal, i.e. polymer mol. wt. and concentration, solvent) is illustrated in Fig.l. The lateral growth faces in the lozenge shaped type of crystal (Fig.la) which is formed at lower temperatures are {110}. Crystals formed at higher temperatures exhibit 'truncated' profiles (Figs. lb,c) and are bound laterally by (110) and (200} growth faces. In addition, the shape of the latter crystals is all the more truncated (Fig.lc), and hence all the more elongated parallel to the b-axis, the higher the crystallization temperature.

An Overview of Cu Wire Intermetallic Compound Formation and a Corrosion Failure Mechanism

2012 ◽  
Author(s):  
Dongmei Meng ◽  
Laura Buck ◽  
James Cargo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Corrosion Mechanism ◽  
Fundamental Study ◽  
Corrosion Failure ◽  
Transmission Electron ◽  
Intermetallic Compound Formation ◽  
Scanning Transmission ◽  
Low K

Abstract Cu needs a higher level of ultrasound combined with bonding force to be bonded to the Al pad properly, not just because Cu is harder than Au, but it is also harder to initiate intermetallic compounds (IMC) formation during bonding. This increases the chances of damaging the metal/low k stack under the bondpad. This paper presents a fundamental study of IMC as well as one example of a failure mode of Cu/Al bonded devices, all based on detailed analysis using scanning electron microscopy, scanning transmission electron microscopy, energy dispersive spectrometers, and transmission electron microscopy. It presents a case study showing a corrosion mechanism of Cu/Al ballbond after 168hr UHAST stress. It is observed that all Cu9Al4 was consumed, while very little copper aluminide remained after 168 hours of UHAST stressing.

scholarly journals Revisiting the Bøggild Intergrowth in Iridescent Labradorite Feldspars: Ordering, Kinetics, and Phase Equilibria

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 727
Author(s):  
Shiyun Jin ◽  
Huifang Xu ◽  
Seungyeol Lee
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atom Probe ◽  
Phase Region ◽  
Two Phase ◽  
Subsolidus Phase ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

The enigmatic Bøggild intergrowth in iridescent labradorite crystals was revisited in light of recent work on the incommensurately modulated structures in the intermediated plagioclase. Five igneous samples and one metamorphic labradorite sample with various compositions and lamellar thicknesses were studied in this paper. The lamellar textures were characterized with conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The compositions of individual lamellae were analyzed with high-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and atom probe tomography (APT). The average structure states of the studied samples were also compared with single-crystal X-ray diffraction data (SC-XRD). The Na-rich lamellae have a composition of An44–48, and the Ca-rich lamellae range from An56 to An63. Significant differences between the lamellar compositions of different samples were observed. The compositions of the Bøggild intergrowth do not only depend on the bulk compositions, but also on the thermal history of the host rock. The implications on the subsolidus phase relationships of the plagioclase feldspar solid solution are discussed. The results cannot be explained by a regular symmetrical solvus such as the Bøggild gap, but they support an inclined two-phase region that closes at low temperature.

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