The biological and medical aspects of ionizing radiation: small motion transducer for radio biological research. (No. 21-3501-0005).

The aim of the study. An analysis of the problems of the development of the dose-effect relationship (DER) in the assessment of the risk under exposure to ionizing radiation (IR) and harmful chemicals (HC) on human health and proposals for improving them. Material and methods. Problems of the development and application of the methodology for assessing the risk of exposure to IR and HC are in the area of delivering DER based on the results of biological experiments and epidemiological studies (ES). These problems are associated with such properties of the effects of exposure to IR and HCh as nonspecificity and latency, low statistical power, fragmentation of the actual information available on the studied effects, possible dependence on the level of the associated spontaneous morbidity or mortality rate. A number of DER models have been developed by national and international organizations. However, between these models, there are significant differences in the choice both of model parameters and the ratio between the multiplicative and additive dependencies on spontaneous effects. The relevance of improving DER models suitable for reliable predictive risk assessments of exposure to IR and HC remains. Results. In modern DER models, the ratio between the multiplicative and additive dependencies on spontaneous effects was chosen by an expert way on the basis of the available results of biological experiments and ESs without sufficient rigorous justification. This was reflected in the different choice of this ratio by different developers. For a more reasonable choice of the ratio, it is proposed to consider two possibilities: 1) implementing additional targeted biological research on the molecular-cellular and organismic levels; 2) a joint analysis of the results of two independent ESs on different cohorts affected by exposure to IR or HC. For IR there is a real opportunity to solve the problem according to the second option. A specific possible method of action in the second direction and an algorithm for its implementation are proposed. Conclusion. Current models of DER for IR and HC require further development, in particular, in terms of the relationship between multiplicative and additive dependencies in DER. A method of justifying the choice of this ratio is proposed and an algorithm for its implementation for IR is described.

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Radiation-induced surface decomposition

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100075592 ◽

1983 ◽

Vol 41 ◽

pp. 368-369

Author(s):

M. L. Knotek

Keyword(s):

Ionizing Radiation ◽

Atomic Structure ◽

Chemical Bonding ◽

Neutral Species ◽

Radiation Induced ◽

Physical And Chemical ◽

Surface Decomposition ◽

The Relationship ◽

Electron And Photon ◽

Surface Bond

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.

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Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100116942 ◽

1975 ◽

Vol 33 ◽

pp. 664-665

Author(s):

Mircea Fotino

Keyword(s):

Experimental Approach ◽

Chromatic Aberration ◽

Resolving Power ◽

Biological Research ◽

Specimen Thickness ◽

Resolution Limit ◽

High Voltage Electron Microscopy ◽

Voltage Electron ◽

Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

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Some problems and solutions in electron energy loss spectroscopy of cryosections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100148666 ◽

1993 ◽

Vol 51 ◽

pp. 566-567

Author(s):

Zhifeng Shao ◽

Ruoya Ho ◽

Andrew P. Somlyo

Keyword(s):

High Resolution ◽

Energy Loss ◽

Electron Energy ◽

Electron Energy Loss Spectroscopy ◽

Biological Research ◽

Specimen Thickness ◽

Elemental Distribution ◽

Electron Dose ◽

Simple Assumption ◽

Electron Energy Loss

Electron energy loss spectroscopy (EELS) has been a powerful tool for high resolution studies of elemental distribution, as well as electronic structure, in thin samples. Its foundation for biological research has been laid out nearly two decades ago, and in the subsequent years it has been subjected to rigorous, but by no means extensive research. In particular, some problems unique to EELS of biological samples, have not been fully resolved. In this article we present a brief summary of recent methodological developments, related to biological applications of EELS, in our laboratory. The main purpose of this work was to maximize the signal to noise ratio (S/N) for trace elemental analysis at a minimum dose, in order to reduce the electron dose and/or time required for the acquisition of high resolution elemental maps of radiation sensitive biological materials.Based on the simple assumption of Poisson distribution of independently scattered electrons, it had been generally assumed that the optimum specimen thickness, at which the S/N is a maximum, must be the total inelastic mean free path of the beam electron in the sample.

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