Accession Number : AD0443675
Title : SYSTEMS FOR COUNTING AND MEASURING SMALL PARTICLES IN FLUIDS
Descriptive Note : Technical memo.
Corporate Author : ARMY BIOLOGICAL LABS FREDERICK MD
Personal Author(s) : Alexander, Nelson E
Report Date : Jun 1964
Pagination or Media Count : 46
Abstract : Research into methods of counting viable bacteria in the presence of many dead ones to yield a rapid microbiological assay did not reach that final objective, but advanced to several important milestones: (1) Methods and apparatus were reduced to practice wherein the light scattered from individual bacteria or clusters in liquid suspension was used for detection and size measurement. (2) The inhibition of mitosis of organisms in a sample, as a method of culturing the microbial giant form to test viability, proved difficult because of the variability of response among individuals in the population to the inhibiting agents and nutrients tested. However, the exploratory experiments produced samples useful for instrument testing. (3) Exploratory research indicated that changes in the dielectric constant of a minute sensing zone could be used to detect the presence of particles in a fluid passing through the zone, and that this method might also show the organization, composition, or uniformity of the particles. (4) We also concluded that the light-scattering apparatus could be used, with minor optical modification, to count fluorescent particles in a liquid.
Descriptors : *MEASUREMENT , *PARTICLES , LIGHT SCATTERING , PARTICLE SIZE , FLUORESCENCE , COUNTING METHODS , DIELECTRIC PROPERTIES , FLUIDS , INHIBITION , BIOASSAY , MITOSIS
Subject Categories : Test Facilities, Equipment and Methods
Distribution Statement : APPROVED FOR PUBLIC RELEASE