A nonequilibrium thermodynamic approach to biological energy conversion systems

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Dowd, Michael
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Chemical and Biological Engineering

The function of the Department of Chemical and Biological Engineering has been to prepare students for the study and application of chemistry in industry. This focus has included preparation for employment in various industries as well as the development, design, and operation of equipment and processes within industry.Through the CBE Department, Iowa State University is nationally recognized for its initiatives in bioinformatics, biomaterials, bioproducts, metabolic/tissue engineering, multiphase computational fluid dynamics, advanced polymeric materials and nanostructured materials.

The Department of Chemical Engineering was founded in 1913 under the Department of Physics and Illuminating Engineering. From 1915 to 1931 it was jointly administered by the Divisions of Industrial Science and Engineering, and from 1931 onward it has been under the Division/College of Engineering. In 1928 it merged with Mining Engineering, and from 1973–1979 it merged with Nuclear Engineering. It became Chemical and Biological Engineering in 2005.

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1913 - present

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  • Department of Chemical Engineering (1913–1928)
  • Department of Chemical and Mining Engineering (1928–1957)
  • Department of Chemical Engineering (1957–1973, 1979–2005)
    • Department of Chemical and Biological Engineering (2005–present)

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Energy conversion devices are commonly built from individual subunits in order to increase the force or flow that can be obtained from the device. Examples occur in both engineering and biology and include the cylinders of an internal combustion engine, the plates of a battery, the cross-bridges of muscle, and the active transport complexes in a cell membrane;This work describes the behavior of assemblies of individual energy converting subunits. The linear phenomenological laws of nonequilibrium thermodynamics are used as constitutional equations that describe the relationship between the forces and flows of a subunit. These relationships along with the restrictions imposed because of the organization of the system are used to derive equations relating the overall flows and forces. Two types of systems have been considered where the total input flow is the sum of the individual input flows, and the output flow is either also the sum of the subunit flows or is the same as each subunit flow. Most of the effort has been directed toward describing systems in which the subunits are not all phenomenologically identical and the fractions of subunit types vary. Systems containing two distinct types of subunit have been studied. Several properties are investigated, including limiting operating states and the input flows needed to support these states. An overall coupling coefficient is derived that represents an effectiveness factor for the system. More complex systems are briefly discussed;As an example, muscle contraction has been considered as a system where the output flow is the same for each subunit. Unfortunately, because it is not yet possible to measure the number of active subunits in muscle, applications of the theory is limited to describing properties that do not depend on the number of subunits. These include the maximum contraction velocity, the isometric rate of adenosine triphosphate hydrolysis, and the system coupling. The theory is applied to phosphorylation, calcium binding and isoenzymes variations that have been found to affect the mechanical and chemical properties of muscle.

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Wed Jan 01 00:00:00 UTC 1986