Philosophy and Contemporary Biological Research

2009 ◽  
pp. 213-224
Author(s):  
Claude Debru
Keyword(s):  
Biological Research

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

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.

Some problems and solutions in electron energy loss spectroscopy of cryosections

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.

DEVELOPMENT OF THE UKRAINIAN FORENSIC MEDICAL INSTITUTIONS IN THE ХХ CENTURY

2017 ◽  
Vol 17 ◽  
pp. 446-456
Author(s):  
V. V. Yusupov
Keyword(s):  
Forensic Medicine ◽  
Medical Examination ◽  
Public Health Care ◽  
Biological Research ◽  
The Public ◽  
Medical Institutions ◽  
Forensic Institutions ◽  
Post War ◽  
Medical Examinations ◽  
The Chairs

The issue of development of forensic institutions of Ukraine in the ХХ century was studied. Until 1917, forensic medical examinations were conducted in the medical compartments of the provincial administrations, at the departments of forensic medicine of universities and in hospitals - by police doctors. The chairs of forensic medicine existed in the St. Vladimir Kyiv University, Kharkiv, Novorosiisk and Lviv Universities. Real organization of Ukrainian forensic medical institutions began in 1919 with the creation of the Medical Examination Department at the People’s Commissariat of Health. In 1923, the Main forensic medical inspection, headed by M. S. Bokarius, was founded. In the provinces the positions of forensic medical inspectors were created. In 1927 the sections of biological research were established in the Kharkiv, Kyiv and Odesa institutes of scientific andforensic expertise,where separate forensic examinations were conducted. In 1949 the institutions of forensic medical examination of the USSR were merged into the Bureau of Forensic Medical Examination, in Ukraine it was held in 1951. It was proved that forensic medical institutions developed at the following chronological stages: 1) until 1917 - forensic medical service in the Ministry of Internal Affairs; 2) 1917-1941 - prewar formation of forensic medical institutions; 3) 1941-1949 -forensic medical institutions during the war and in the first post-war years; 4) 1949-1990s - period of development of the bureau of forensic medical examinations of the countries of the USSR; 5) since the 1990s - development of expert institutions in the public health care system in independent postSoviet states. It’s stressed that formation of the forensic institutions in Ukraine is closely related with the development of forensic medicine departments of higher educational establishments. Forensic medicine departments were the basisfor practicalforensic medicine, professors provided daily assistance to forensic medical experts.

Establishing Standard Protocols for Bacterial Culture in Biological Research in Canisters (BRIC) Hardware

2020 ◽  
Vol 4 (2) ◽  
pp. 58-69 ◽  
Author(s):  
Patricia Fajardo-Cavazos ◽  
Wayne L. Nicholson
Keyword(s):  
Gene Expression ◽  
Bacterial Culture ◽  
Culture Conditions ◽  
Media Culture ◽  
Ground Control ◽  
Biological Research ◽  
Confounding Factors ◽  
Cross Experiment ◽  
Spaceflight Experiments ◽  
Control Samples

AbstractThe NASA GeneLab Data System (GLDS) was recently developed to facilitate cross-experiment comparisons in order to understand the response of microorganisms to the human spaceflight environment. However, prior spaceflight experiments have been conducted using a wide variety of different hardware, media, culture conditions, and procedures. Such confounding factors could potentially mask true differences in gene expression between spaceflight and ground control samples. In an attempt to mitigate such confounding factors, we describe here the development of a standardized set of hardware, media, and protocols for liquid cultivation of microbes in Biological Research in Canisters (BRIC) spaceflight hardware, using the model bacteria Bacillus subtilis strain 168 and Staphylococcus aureus strain UAMS-1 as examples.

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