Elemental composition of the dense bodies of rat platelets determined by electron probe X-ray microanalysis of freeze-substituted sections

1983 ◽  
Vol 77 (3) ◽  
pp. 329-337 ◽  
Author(s):  
T. Daimon ◽  
V. Mizuhira ◽  
M. Ono ◽  
K. Uchida
Keyword(s):  
Elemental Composition ◽  
Electron Probe ◽  
X Ray ◽  
Dense Bodies ◽  
Rat Platelets

Quantitative Electron Microprobe Studies of Human-Platelet Dense Bodies

1975 ◽  
Vol 33 ◽  
pp. 322-323
Author(s):  
Y. Tanaka ◽  
J.L. Costa ◽  
K.D. Pettigrew ◽  
Y. Yoda ◽  
R.J. Cushing
Keyword(s):  
Elemental Composition ◽  
Electron Microprobe ◽  
Coefficient Of Variation ◽  
Human Platelet ◽  
Beam Spot ◽  
X Ray ◽  
Dense Bodies ◽  
Analysis System ◽  
Whole Mounts ◽  
Prominent Peak

As seen in air-dried whole mounts, human-platelet dense bodies (DB) are discrete, electron-opaque structures ranging in size from approximately 50 nm to 1000 nm in diameter (Fig. 1). We have examined DB elemental composition and peak-to-background (p/bg) ratios using a Hitachi HU-12A microscope in the transmission-scanning mode and a Kevex energy-dispersive X-ray detector and analysis system. Qualitatively, spectra from probed DB showed strong signals for calcium and phosphorous, and a less prominent peak for potassium. No magnesium peak was detected (Fig. 2).Quantitatively, probing 11 randomly-selected DB with a beam spot approximately 10 nm in diameter (75 kv accelerating voltage) gave phosphorous p/bg ratios with a coefficient of variation (CV) of 71.32, calcium p/bg ratios with a CV of 75.34, and elemental phosphorous/calcium (P/Ca) ratios with a CV of 18.10 (Fig. 3). Peak-to-background ratios for both elements demonstrated low correlations with the area of the DB probed (r = 0.12 and 0. 39 for phosphorous and calcium, respectively, based on a sample size of 67 DB's), suggesting that only a small fraction of the total DB area was being sampled.

In situ metal mirror cryofixation of rat kidney for electron probe x-ray microanalysis

1992 ◽  
Vol 50 (1) ◽  
pp. 742-743
Author(s):  
Craig C. Freudenrich ◽  
Daniel Hockett ◽  
Kerri Winter ◽  
Peter Ingram ◽  
Ann LeFurgey
Keyword(s):  
Proximal Tubule ◽  
Elemental Composition ◽  
Cell Cultures ◽  
Electron Probe ◽  
Rat Kidney ◽  
X Ray ◽  
Intact Tissue ◽  
Subcellular Compartments ◽  
Excellent Preservation

Many studies of proximal tubule function require information about the elemental composition in subcellular compartments that can be obtained by electron probe x-ray microanalysis (EPXMA). While experiments of this type have been performed on isolated proximal tubule preparations, it is also necessary to conduct parallel experiments on intact tissue to verify those results obtained with isolated tubules. One limitation in conducting EPXMA analysis on whole tissue is obtaining adequately cryopreserved tissue. Metal mirror cryofixation techniques have yielded excellent preservation in dissected tissues or cell cultures. Therefore, experiments were performed to assess the efficacy of in situ metal minor fixation of the intact rat kidney.

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

Spatial resolution of X-ray microanalysis in thin foils

1978 ◽  
Vol 36 (1) ◽  
pp. 544-545
Author(s):  
R. Hutchings ◽  
I.P. Jones ◽  
M.H. Loretto ◽  
R.E. Smallman
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Beam Divergence ◽  
Inelastic Interaction ◽  
Specimen Thickness ◽  
High Current ◽  
Beam Spreading ◽  
X Ray ◽  
Thin Foils ◽  
Complex Calculation

There is increasing interest in X-ray microanalysis of thin specimens and the present paper attempts to define some of the factors which govern the spatial resolution of this type of microanalysis. One of these factors is the spreading of the electron probe as it is transmitted through the specimen. There will always be some beam-spreading with small electron probes, because of the inevitable beam divergence associated with small, high current probes; a lower limit to the spatial resolution is thus 2αst where 2αs is the beam divergence and t the specimen thickness.In addition there will of course be beam spreading caused by elastic and inelastic interaction between the electron beam and the specimen. The angle through which electrons are scattered by the various scattering processes can vary from zero to 180° and it is clearly a very complex calculation to determine the effective size of the beam as it propagates through the specimen.

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