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Experimental and theoretical analysis of the rate of solvent equilibration in the hanging drop method of protein crystal growthThe principles of the hanging-drop method of crystal growth are discussed, and the rate of water evaporation in a water droplet (containing protein, buffer, and a precipitating agent) suspended above a well containing a double concentration of precipitating agent is investigated theoretically. It is shown that, on earth, the rate of evaporation may be determined from diffusion theory and the colligative properties of solutions. The parameters affecting the rate of evaporation include the temperature, the vapor pressure of water, the ionization constant of the salt, the volume of the drop, the contact angle between the droplet and the coverslip, the number of moles of salt in the droplet, the number of moles of water and salt in the well, the molar volumes of water and salt, the distance from the droplet to the well, and the coefficient of diffusion of water vapor through air. To test the theoretical equations, hanging-drop experiments were conducted using various reagent concentrations in 25-microliter droplets and measuring the evaporation times at 4 C and 25 C. The results showed good agreement with the theory.
Document ID
Document Type
Reprint (Version printed in journal)
Fowlis, William W.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Delucas, Lawrence J.
(Alabama, University Birmingham, United States)
Twigg, Pamela J.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Howard, Sandra B.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Meehan, Edward J.
(Alabama, University Huntsville, United States)
Date Acquired
August 13, 2013
Publication Date
July 1, 1988
Publication Information
Publication: Journal of Crystal Growth
Volume: 90
Issue: 1-3
ISSN: 0022-0248
Subject Category
Materials Processing
Accession Number
Funding Number(s)
Distribution Limits

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