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Single polymer dynamics in an elongational flow
Single polymer dynamics in an elongational flow.
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The stretching of individual polymers in a spatially homogeneous velocity gradient was observed through use of fluorescently labeled DNA molecules. The probability distribution of molecular extension was determined as a function of time and strain rate. Although some molecules reached steady state, the average extension did not, even after a approximately 300-fold distortion of the underlying fluid element. At the highest strain rates, distinct conformational shapes with differing dynamics were observed. There was considerable variation in the onset of stretching, and chains with a dumbbell shape stretched more rapidly than folded ones. As the strain rate was increased, chains did not deform with the fluid element. The steady-state extension can be described by a model consisting of two beads connected by a spring representing the entropic elasticity of a worm-like chain, but the average dynamics cannot.
Perkins TT, Smith DE, Chu S
Science (New York, N.Y.)
1997-06-27 00:00
276
5321
2016-21
Bacteriophage lambda,Chemistry, Physical,DNA, Viral,Entropy,Fluorescence,Fluorescent Dyes,Models, Chemical,Nucleic Acid Conformation,Stress, Mechanical,Thermodynamics,DNA, Viral,Fluorescent Dyes
Department of Physics, Stanford University, Stanford, CA 94305, USA
Science
NIGMS GM33289
0036-8075
1006
True
9197259
