TOF Measurements of Pulsed Neutrons for Texture Analysis of Low Symmetry Materials

1989 ◽  
Vol 166 ◽  
Author(s):  
Allen C. Larson ◽  
Phillip J. Vergamini ◽  
Hans-Rudolf Wenk
Keyword(s):  
Wave Length ◽  
Preferred Orientation ◽  
Strain History ◽  
Standard Samples ◽  
Large Wave ◽  
Pole Figures ◽  
Length Range ◽  
History Of ◽  
Lattice Planes ◽  
Temperature Strain

ABSTRACTThe single crystal diffractometer at LANSCE, SCD, provides an ideal ca- pability for the study of preferred orientation in geological samples by time-of flight(TOF) measurement of pulsed neutrons. The 2-d position sensitive neutron detector with the large wave length range allows one to measure the complete dis- tribution of intensities for several poles very quickly. Each histogram covers about πt2/16 radians of reciprocal space and contains information from all possible poles visible with the wave length range used, usually about 0.5 to 5.OÅ. With this method complete pole figures of many lattice planes can be constructed from only 12 to 20 sample orientations as compared to over 1000 sample settings per lattice plane using conventional diffractometers.Pole figures from measurements of experimentally deformed standard samples of calcite and quartzite with a known history of deformation provide in- formation about deformation mechanisms and their temperature/strain history. This information can be applied to interpret preferred orientation of naturally de- formed rocks.

Observations of the Zeta Spectrum in the Wave-length Range 16 Å–400 Å

Nature ◽  
1963 ◽  
Vol 200 (4913) ◽  
pp. 1303-1304 ◽  
Author(s):  
B. C. FAWCETT ◽  
A. H. GABRIEL ◽  
W. G. GRIFFIN ◽  
B. B. JONES ◽  
R. WILSON
Keyword(s):  
Wave Length ◽  
Length Range

scholarly journals The Odyssey of the Ancestral Escherich Strain through Culture Collections: an Example of Allopatric Diversification

mSphere ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
M. Desroches ◽  
G. Royer ◽  
D. Roche ◽  
M. Mercier-Darty ◽  
D. Vallenet ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Efflux Pump ◽  
Strain History ◽  
Culture Collections ◽  
E Coli ◽  
Molecular Features ◽  
Natural Isolates ◽  
History Of ◽  
Encoding Genes

Mutator phenotypes have been described in laboratory-evolved bacteria, as well as in natural isolates. Several genes can be impacted, each of them being associated with a typical mutational spectrum. By studying one of the oldest strains available, the ancestral Escherich strain, we were able to identify its mutator status leading to tremendous genetic diversity among the isolates from various collections and allowing us to reconstruct the phylogeographic history of the strain. This mutator phenotype was probably acquired during the storage of the strain, promoting adaptation to a specific environment. Other mutations inrpoSand efflux pump- and porin-encoding genes highlight the acclimatization of the strain through self-preservation and nutritional competence regulation. This strain history can be viewed as unintentional experimental evolution in culture collections all over the word since 1885, mimicking the long-term experimental evolution ofE. coliof Lenski et al. (O. Tenaillon, J. E. Barrick, N. Ribeck, D. E. Deatherage, J. L. Blanchard, A. Dasgupta, G. C. Wu, S. Wielgoss, S. Cruveiller, C. Médigue, D. Schneider, and R. E. Lenski, Nature 536:165–170, 2016, https://doi.org/10.1038/nature18959) that shares numerous molecular features.

The Auroral Spectrum in the Wave-Length Range 3300-8900.

1952 ◽  
Vol 116 ◽  
pp. 433 ◽  
Author(s):  
A. W. Petrie ◽  
R. Small
Keyword(s):  
Wave Length ◽  
Length Range

A Comparison of (100) Hg1−x Cdx Te and Hg1−x ZnxTe Grown By Molecular Beam Epitaxy

1987 ◽  
Vol 102 ◽  
Author(s):  
R. D. Feldman ◽  
R. F. Austin ◽  
P. M. Bridenbaugh
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Near Infrared ◽  
Wave Length ◽  
High Electron ◽  
Mbe Growth ◽  
Suitable Material ◽  
Zn Content ◽  
Length Range ◽  
Very High

ABSTRACTFilms of HgCdTe with x < 0.6 and of HgZnTe with x < 0.26 have been grown by molecular beam epitaxy (MBE). Very high electron mobilities have been achieved for both materials in the small bandgap region. Hall mobilities at 77K reach 4.8 × 105 cm2 /V-s for Hg0 87 Zn0.13 Te, and 3.1 × 105 cm2/V-s for Hg0.87 Zn0.13 Te. HgCdTe growth was easily extended to the 1.5 – 3 μm wave length range. Attempts to extend HgZnTe to these bandgaps were unsuccessful due to defects that are induced by surface roughness in high Zn-content films. These results suggest that HgCdTe is the more suitable material for MBE growth for near infrared applications.

Anisotropy of experimentally compressed kaolinite-illite-quartz mixtures

Geophysics ◽  
2009 ◽  
Vol 74 (1) ◽  
pp. D13-D23 ◽  
Author(s):  
Marco Voltolini ◽  
Hans-Rudolf Wenk ◽  
Nazmul Haque Mondol ◽  
Knut Bjørlykke ◽  
Jens Jahren
Keyword(s):  
Single Crystal ◽  
Elastic Properties ◽  
Compaction Pressure ◽  
Clay Content ◽  
Orientation Distribution ◽  
Rietveld Analysis ◽  
Preferred Orientation ◽  
P Wave ◽  
Velocity Anisotropy ◽  
Pole Figures

The anisotropy of physical properties is a well-known characteristic of many clay-bearing rocks. This anisotropy has important implications for elastic properties of rocks and must be considered in seismic modeling. Preferred orientation of clay minerals is an important factor causing anisotropy in clay-bearing rocks such as shales and mudstones that are the main cap rocks of oil reservoirs. The preferred orientation of clays depends mostly on the amount of clays and the degree of compaction. To study the effect of these parameters, we prepared several samples compressing (at two effective vertical stresses) a mixture of clays (illite and kaolinite) and quartz (silt) with different clay/quartz ratios. The preferred orientation of the phases was quantified with Rietveld analysis on synchrotron hard X-ray images. Pole figures for kaolinite and illite display a preferred orientationof clay platelets perpendicular to the compaction direction, increasing in strength with clay content and compaction pressure. Quartz particles have a random orientation distribution. Aggregate elastic properties can be estimated by averaging the single-crystal properties over the orientation distribution obtained from the diffraction data analysis. Calculated P-wave velocity anisotropy ranges from 0% (pure quartz sample) to 44% (pure clay sample, highly compacted), but calculated velocities are much higher than measured velocities. This is attributed to uncertainties about single-crystal elastic properties and oriented micropores and limited grain contacts that are not accounted for in the model. In this work, we present an effective method to obtain quantitative data, helping to evaluate the role of clay percentage and compaction pressure on the anisotropy of elastic properties of clay-bearing rocks.

scholarly journals First Results and Discoveries with the ISO Short-Wavelength Spectrometer

1998 ◽  
Vol 11 (2) ◽  
pp. 1113-1115
Author(s):  
Thijs De Graauw
Keyword(s):  
Spectral Resolution ◽  
Short Wavelength ◽  
Wave Length ◽  
Space Observatory ◽  
Infrared Space Observatory ◽  
Length Range ◽  
First Results ◽  
Scientific Results

AbstractThe Short-Wavelength Spectrometer(SWS) is one of the four instruments on-board of ESA’s Infrared Space Observatory(ISO), launched on 15 Nov. 1995. It covers the wave-length range of 2.38-45.2μm with a spectral resolution ranging from 1000-2000. An overview is given of the in-orbit performance and a summary of the main scientific results and discoveries obtained in the first 18 months of operation of the ISO-SWS.

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