Biomaterial Database

Image contrast of biological materials in high-voltage electron microscopy. 1997

P Bhakat, and D K Bhattacharya

Department of Biochemistry and Biophysics, University of Kalyani, India.

A new and simple expression has been formulated for the estimation of contrast of amorphous specimens in the tilted-beam mode of dark-field (DF) imaging in a high-voltage electron microscope. DF contrasts have been calculated for AIDS1.DNA, Salmonella typhimurium DNA, human haemoglobin and myoglobin of sperm whale in the range 0.1-3.0 MV and compared with the corresponding bright-field (BF) contrasts. DF contrast is seen to be significantly greater than BF contrast for a wide range of microscope apertures (alpha) and voltages (phi). The ratio of DF to BF contrast was observed to increase with increasing phi and alpha for all the aforesaid specimens.

UI	MeSH Term	Description	Entries
D007089	Image Enhancement	Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural MICROSCOPY, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level.	Image Quality Enhancement,Enhancement, Image,Enhancement, Image Quality,Enhancements, Image,Enhancements, Image Quality,Image Enhancements,Image Quality Enhancements,Quality Enhancement, Image,Quality Enhancements, Image
D008297	Male		Males
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man