Determination of the resolving power of optical systems in the formation of speckle images

2000 ◽  
Vol 88 (1) ◽  
pp. 102-106 ◽  
Author(s):  
G. N. Mal’tsev
Keyword(s):  
Resolving Power ◽  
Optical Systems

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

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.

scholarly journals Temperature Gradient Measurements in Hydrothermal Areas of Georgia

2018 ◽  
Vol 1 (1) ◽  
pp. 14-17
Author(s):  
Andreas Weller ◽  
Sepehr Sangin ◽  
Günter Buntebarth ◽  
George Melikadze
Keyword(s):  
Temperature Field ◽  
Fluid Flows ◽  
Temperature Measurements ◽  
Resolving Power ◽  
The Caucasus ◽  
Caucasus Region ◽  
Different Depths ◽  
Subsurface Fluid ◽  
Gradient Measurements

The project uses results of temperature measurements in shallow boreholes to determine the geothermal gradients for a selected set of wells in Georgia. The hydrothermal flow in the Caucasus region driven by ongoing tectonic activities causes a varying temperature field that impedes determination of stable temperature gradients. Conventional temperature logging provides only a snapshot of the temperature distribution in a well. Therefore, the methodology adopted in this study is based on continuous stationary measurements with up to eight temperature sensors fixed at different depths in the wells. Temperature measurements have been performed in 14 wells using thermometers with resolving power of 0.01 K. The temperature field was recorded during periods ranging from 16 hours to 4 days. This practice of measurements enabled detection of thermal effects of fluid flows within the selected set of boreholes. Considering the 14 wells that were selected for this study, eight showed signs of stability in temperature increase versus depth and the remaining seven wells revealed signs of instability due subsurface fluid flows.

Novel approach for exceeding the resolving power of optical systems

1999 ◽  
Author(s):  
Zeev Zalevsky ◽  
David Mendlovic ◽  
Adolf W. Lohmann ◽  
Gal Shabtay
Keyword(s):  
Resolving Power ◽  
Optical Systems ◽  
Novel Approach

Capillary Gas Chromatographic Determination of T-2 Toxin, HT-2 Toxin, and Diacetoxyscirpenol in Cereal Grains

1984 ◽  
Vol 67 (6) ◽  
pp. 1105-1107
Author(s):  
Huguette Cohen ◽  
Michel Lapointe
Keyword(s):  
Electron Capture ◽  
Impact Ionization ◽  
Chromatographic Determination ◽  
Fused Silica ◽  
Electron Capture Detector ◽  
Resolving Power ◽  
Cereal Grains ◽  
Gas Chromatography Mass Spectrometry ◽  
Silica Column

Abstract A capillary gas chromatographic (GC) method using an electron capture detector is described for determining T-2 and HT-2 toxins and diacetoxyscirpenol (DAS) in cereal grains at levels as low as 100 ppb for T-2 and DAS and 50 ppb for HT-2. Samples are extracted with methanol-water according to the Scott method, and further purified on a silica gel cartridge and a cyano column. Heptafluorobutyrylimidazole (HFBI) is added to form the esters of the analytes. Ester(s) of T-2, HT-2 and DAS are separated on a 30 m × 0.32 mm DB-5 fused silica column and measured with a "Ni electron capture detector. Samples were confimed by gas chromatography/mass spectrometry using electron impact ionization and single ion monitoring at the molecular mass of 501.11 m/z for T-2, 665.08 m/z for HT-2, and 502.12 m/z for DAS at 10 000 resolving power. The method was applied to wheat, oats, and barley. Average recoveries ranged from a low of 65% for T- 2 in barley to a high of 99% for DAS in oats.

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