Precipitation of Uraninite in Chlorite-Bearing Veins of the Hydrothermal Alteration Zone (Argile De Pile) of the Natural Nuclear Reactor at Bangombé, Republic of Gabon

1994 ◽  
Vol 353 ◽  
Author(s):  
P. Eberly ◽  
J. Janeczek ◽  
R. Ewing
Keyword(s):  
Hydrothermal Alteration ◽  
Nuclear Reactor ◽  
Energy Dispersive ◽  
Alteration Zone ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Alteration Halo ◽  
Sheet Silicates ◽  
Backscattered Electron ◽  
Electron Imaging

AbstractThis paper describes the mineralogy of a phyllosilicate/uraninite/galena-bearing vein located within the hydrothermal alteration halo associated with the Bangombé reactor. Phyllosilicates within the vein include a trioctahedral Al-Mg-Fe chlorite (ripidolite), Al-rich clay (kaolinite and/or donbassite) and illite. Textural relations obtained by backscattered-electron imaging suggest that ripidolite crystallized first among the sheet silicates. Uraninite is spatially associated with ripidolite and probably precipitated at a later time. While energy-dispersive x-ray analyses suggest that the uranium phase is predominantly uraninite, coffinite or other phases may also be present.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

scholarly journals Phase relationships in the Al-rich region of the Al-Y-Zr system

2017 ◽  
Vol 53 (1) ◽  
pp. 9-12 ◽  
Author(s):  
X. Bao ◽  
L. Liu ◽  
S. Huang ◽  
Y. Jiang ◽  
X. Wang ◽  
...  
Keyword(s):  
First Principle ◽  
Rich Region ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
First Principle Calculations ◽  
Three Phase ◽  
Backscattered Electron ◽  
Electron Imaging ◽  
Scanning Electron ◽  
Phase Relationships

The phase relations in the Al-Y-Zr ternary system at 873 K have been investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) in backscattered electron imaging (BSE) modes. Six three-phase equilibria are determined and no ternary compound is observed. In the meantime, first principle calculations are used to provide theoretical guidance to understand the experimental results.

scholarly journals Silicon location through backscattered electron imaging and X-ray microanalysis in leaves of Cyperus ligularis L. and Rhynchospora aberrans C. B. Clarke (Cyperaceae)

2012 ◽  
Vol 26 (2) ◽  
pp. 275-280 ◽  
Author(s):  
Maria Emília Maranhão Estelita ◽  
Ana Claudia Rodrigues
Keyword(s):  
Cell Walls ◽  
Colloidal Silica ◽  
Structural Changes ◽  
Epidermal Cells ◽  
Vascular Bundles ◽  
Backscattered Electron Imaging ◽  
X Ray ◽  
Backscattered Electron ◽  
Taxonomic Groups ◽  
Electron Imaging

The Cyperaceae show the ability to incorporate silicon by depositing colloidal silica, which is recorded by the occurrence of projections in the form of cones, in inner tangential walls of some epidermal cells or "silica cells". Leaves of C. ligularis and R. aberrans were analyzed through the technique of electron backscatter. Cyperus ligularis accumulates silica, in addition to "silica cells", in some stomata, trichomes and the cell walls that surround the cavities of the aerenchyma. The silica in the latter occurs in various forms; however, the cells located near the vascular bundles have conical projections, similar to those of the epidermis. Rhynchospora aberrans presents "silica cells" whose projections have tapered "satellites". In this species, silica also occurs in stomata and certain epidermal cells adjacent to them. It appears that the silicon deposition occurs in combination with the wall (with no apparent structural changes), and structures of secretion, or projections of the wall. These structural changes in the species, and location, are probably related to functional and environmental factors, especially the soil, in addition to relation with taxonomic groups.

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