scholarly journals X-ray photons produced from a plasma-cathode electron beam for radiation biology applications

2021 ◽  
Vol 118 (4) ◽  
pp. 044102
Author(s):  
F. Gobet ◽  
P. Barberet ◽  
L. Courtois ◽  
G. Deves ◽  
J. Gardelle ◽  
...  
Author(s):  
R. Sinclair ◽  
B.E. Jacobson

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).


Author(s):  
W. Brünger

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.


Author(s):  
Imre Pozsgai ◽  
Klara Erdöhalmi-Torok

The paintings by the great Hungarian master Mihaly Munkacsy (1844-1900) made in an 8-9 years period of his activity are deteriorating. The most conspicuous sign of the deterioration is an intensive darkening. We have made an attempt by electron beam microanalysis to clarify the causes of the darkening. The importance of a study like this is increased by the fact that a similar darkening can be observed on the paintings by Munkacsy’s contemporaries e.g Courbet and Makart. A thick brown mass the so called bitumen used by Munkacsy for grounding and also as a paint is believed by the art historians to cause the darkening.For this study, paint specimens were taken from the following paintings: “Studio”, “Farewell” and the “Portrait of the Master’s Wife”, all of them are the property of the Hungarian National Gallery. The paint samples were embedded in a polyester resin “Poly-Pol PS-230” and after grinding and polishing their cross section was used for x-ray mapping.


Author(s):  
M.E. Cantino ◽  
M.K. Goddard ◽  
L.E. Wilkinson ◽  
D.E. Johnson

Quantification in biological x-ray microanalysis depends on accurate evaluation of mass loss. Although several studies have addressed the problem of electron beam induced mass loss from organic samples (eg., 1,2). uncertainty persists as to the dose dependence, the extent of loss, the elemental constituents affected, and the variation in loss for different materials and tissues. in the work described here, we used x-ray counting rate changes to measure mass loss in albumin (used as a quantification standard), salivary gland, and muscle.In order to measure mass loss at low doses (10-4 coul/cm2 ) large samples were needed. While freeze-dried salivary gland sections of the required dimensions were available, muscle sections of this size were difficult to obtain. To simulate large muscle sections, frog or rat muscle homogenate was injected between formvar films which were then stretched over slot grids and freeze-dried. Albumin samples were prepared by a similar procedure. using a solution of bovine serum albumin in water. Samples were irradiated in the STEM mode of a JEOL 100C.


2020 ◽  
Author(s):  
Mohit Tyagi ◽  
P. S. Sarkar ◽  
R. S. Sengar ◽  
Ashwani Kumar ◽  
Jagannath ◽  
...  

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1246
Author(s):  
Stefan Valkov ◽  
Dimitar Dechev ◽  
Nikolay Ivanov ◽  
Ruslan Bezdushnyi ◽  
Maria Ormanova ◽  
...  

In this study, we present the results of Young’s modulus and coefficient of friction (COF) of Ti–Ta surface alloys formed by electron-beam surface alloying by a scanning electron beam. Ta films were deposited on the top of Ti substrates, and the specimens were then electron-beam surface alloyed, where the beam power was varied from 750 to 1750 W. The structure of the samples was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Young’s modulus was studied by a nanoindentation test. The coefficient of friction was studied by a micromechanical wear experiment. It was found that at 750 W, the Ta film remained undissolved on the top of the Ti, and no alloyed zone was observed. By an increase in the beam power to 1250 and 1750 W, a distinguished alloyed zone is formed, where it is much thicker in the case of 1750 W. The structure of the obtained surface alloys is in the form of double-phase α’and β. In both surface alloys formed by a beam power of 1250 and 1750 W, respectively, Young’s modulus decreases about two times due to different reasons: in the case of alloying by 1250 W, the observed drop is attributed to the larger amount of the β phase, while at 1750 W is it due to the weaker binding forces between the atoms. The results obtained for the COF show that the formation of the Ti–Ta surface alloy on the top of Ti substrate leads to a decrease in the coefficient of friction, where the effect is more pronounced in the case of the formation of Ti–Ta surface alloys by a beam power of 1250 W.


2021 ◽  
Author(s):  
A. N. Darmaev ◽  
S. P. Morev ◽  
V. M. Sablin ◽  
N. N. Potrakhov ◽  
A. S. Baklin
Keyword(s):  

1991 ◽  
Vol 13 (1-4) ◽  
pp. 165-172 ◽  
Author(s):  
M.G. Rosenfield ◽  
S.A. Rishton ◽  
D.P. Kern ◽  
D.E. Seeger ◽  
C.A. Whiting

2018 ◽  
Vol 143 ◽  
pp. 8-13
Author(s):  
Huaili Qin ◽  
Guang Yang ◽  
Shan Kuang ◽  
Qiang Wang ◽  
Jingjing Liu ◽  
...  

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