Ultrastructural and X-ray analytical studies on intranuclear bismuth inclusions

1976 ◽  
Vol 21 (1) ◽  
pp. 45-55
Author(s):  
F. N. Ghadially ◽  
N. K. Yong
Keyword(s):  
X Ray ◽  
Analytical Studies

Structural and analytical studies of the silicified macrohairs from the lemma of the grass Phalaris canariensis L

1984 ◽  
Vol 222 (1229) ◽  
pp. 427-438 ◽  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silica Particles ◽  
Time Dependent ◽  
Energy Dispersive ◽  
X Ray ◽  
Analytical Studies ◽  
Transmission Electron ◽  
Cellular Control ◽  
Phalaris Canariensis

Silicified macrohairs from mature and immature lemmas of the grass Phalaris canariensis L. have been studied by scanning (s.e.m.) and transmission electron microscopy (t.e.m.) and energy dispersive X-ray analysis (e.d.X.a.) at various times after emergence of the inflorescence. Within the macrohairs a variety of morphologies of silica particles was observed. E.d.X.a. revealed the time-dependent concentrations in the macrohairs of the elements K, Cl, P, and S, in addition to Si. Much lower levels of these elements were found in highly silicified mature macrohairs than in the immature macrohairs. It is proposed that the hairs are silicified under strict cellular control.

GEOMETRICAL ABERRATIONS IN THE VON HAMOS AND THE PLANE BRAGG CRYSTAL SPECTROMETERS

1997 ◽  
Vol 07 (03n04) ◽  
pp. 117-133 ◽  
Author(s):  
T. Tadic ◽  
Y. Mokuno ◽  
Y. Horino ◽  
M. Jaksic
Keyword(s):  
Numerical Model ◽  
Ray Tracing ◽  
Numerical Calculations ◽  
X Ray Diffraction ◽  
Pixe Analysis ◽  
X Ray ◽  
Analytical Studies ◽  
Position Sensitive ◽  
Produce Line

Numerical calculations of the effect of the finite dimensions and orientations of source and crystal are presented for plane and von Hamos Bragg crystal spectrometers for PIXE analysis, combined with a position sensitive (X-ray) detector. Analytical studies of all effects are provided. It is shown that some parameters can produce line shifts and asymmetries. A numerical model for an X-ray diffraction ray-tracing procedure for a crystal Bragg spectrometer is described.

The Gold-rich Indide Sr5Au13.5In8.5

2011 ◽  
Vol 66 (11) ◽  
pp. 1101-1106 ◽  
Author(s):  
Ihor Muts ◽  
Ute Ch. Rodewald ◽  
Vasyl’ I. Zaremba ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analytical Studies ◽  
New Type

The orthorhombic indide Sr5Au13.5In8.5 was obtained during phase-analytical studies of the Sr-Au-In system. This new indide is formed upon melting of the elements in a sealed tantalum tube. Sr5Au13.5In8.5 was characterized on the basis of powder and single-crystal X-ray diffraction: Pmmn, a = 476.37(9), b = 2927.5(9), c = 894.9(2) pm, wR2 = 0.056, 2355 F2 values, 87 variables. The structure is of a new type. The gold and indium atoms build up a complex three-dimensional [Au13.5In8.5] polyanionic network in which the strontium atoms fill channels which extend in the a direction. One site within the polyanion shows Au/In mixing. The Sr5Au13.5In8.5 structure is composed of SrAu3In3 -and SrAu-related slabs

Analytical studies of a backscatter x-ray imaging landmine detection system

1996 ◽  
Author(s):  
Shyam P. Keshavmurthy ◽  
Edward T. Dugan ◽  
Joseph C. Wehlburg ◽  
Alan M. Jacobs
Keyword(s):  
Detection System ◽  
Landmine Detection ◽  
X Ray ◽  
Analytical Studies ◽  
X Ray Imaging

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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