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


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/443675.pdf


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
      Physical Chemistry


Distribution Statement : APPROVED FOR PUBLIC RELEASE