A New Method of Assessing Myocardial Ischemic Injury During Cardiac Operations: Electron Probe X-Ray Microanalysis

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.

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Spatial resolution of X-ray microanalysis in thin foils

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109860 ◽

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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High spatial resolution x-ray microanalysis of interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137793 ◽

1995 ◽

Vol 53 ◽

pp. 284-285

Author(s):

J. R. Michael

Keyword(s):

Spatial Resolution ◽

Electron Probe ◽

Solid Angle ◽

Collection Efficiency ◽

Spatial Scales ◽

Energy Dispersive Spectrometer ◽

X Rays ◽

X Ray ◽

Probe Size ◽

Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

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Microchemical imaging in biomedical research

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130225 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1118-1119

Author(s):

P. Ingram

Keyword(s):

Data Analysis ◽

Electron Probe ◽

The Other ◽

X Ray ◽

Cell Element ◽

Physiological Information ◽

Functional States ◽

Elemental Maps ◽

Electron Energy Loss ◽

Secondary Ion

It is well established that unique physiological information can be obtained by rapidly freezing cells in various functional states and analyzing the cell element content and distribution by electron probe x-ray microanalysis. (The other techniques of microanalysis that are amenable to imaging, such as electron energy loss spectroscopy, secondary ion mass spectroscopy, particle induced x-ray emission etc., are not addressed in this tutorial.) However, the usual processes of data acquisition are labor intensive and lengthy, requiring that x-ray counts be collected from individually selected regions of each cell in question and that data analysis be performed subsequent to data collection. A judicious combination of quantitative elemental maps and static raster probes adds not only an additional overall perception of what is occurring during a particular biological manipulation or event, but substantially increases data productivity. Recent advances in microcomputer instrumentation and software have made readily feasible the acquisition and processing of digital quantitative x-ray maps of one to several cells.

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Reduction of Potassium in Kidney Proximal Tubules to Aid in Electron Probe X-Ray Microanalysis of Calcium

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100119193 ◽

1985 ◽

Vol 43 ◽

pp. 474-475

Author(s):

A. LeFurgey ◽

P. Ingram ◽

L.J. Mandel

Keyword(s):

Smooth Muscle ◽

Proximal Tubule ◽

Electron Probe ◽

Clinical Applications ◽

Proximal Tubules ◽

Rabbit Kidney ◽

Target Cells ◽

X Ray ◽

Freeze Dried

For quantitative determination of subcellular Ca distribution by electron probe x-ray microanalysis, decreasing (and/or eliminating) the K content of the cell maximizes the ability to accurately separate the overlapping K Kß and Ca Kα peaks in the x-ray spectra. For example, rubidium has been effectively substituted for potassium in smooth muscle cells, thus giving an improvement in calcium measurements. Ouabain, a cardiac glycoside widely used in experimental and clinical applications, inhibits Na-K ATPase at the cell membrane and thus alters the cytoplasmic ion (Na,K) content of target cells. In epithelial cells primarily involved in active transport, such as the proximal tubule of the rabbit kidney, ouabain rapidly (t1/2= 2 mins) causes a decrease2 in intracellular K, but does not change intracellular total or free Ca for up to 30 mins. In the present study we have taken advantage of this effect of ouabain to determine the mitochondrial and cytoplasmic Ca content in freeze-dried cryosections of kidney proximal tubule by electron probe x-ray microanalysis.

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