Elasticity, molecular basis

B. Erman and J.E. Mark, The molecular basis of rubberlike elasticity. In J.E. Mark, B. Erman and... 

In Eq. (4.13) NT is the total number of internal degrees of freedom per unit volume which relax by simple diffusion (NT — 3vN for dilute solutions), and t, is the relaxation time of the ith normal mode (/ = 1,2,3NT) for small disturbances. Equation (4.13), together with a stipulation that all relaxation times have the same temperature coefficient, provides, in fact, the molecular basis of time-temperature superposition in linear viscoelasticity. It also reduces to the expression for the equilibrium shear modulus in the kinetic theory of rubber elasticity when tj = oo for some of the modes. 

Fibrillin microfibrils are widely distributed extracellular matrix assemblies that endow elastic and non elastic connective tissues with long-range elasticity. They direct tropoelastin deposition during elastic fibrillogenesis and form an outer mantle for mature elastic fibers. Microfibril arrays are also abundant in dynamic tissues that do not express elastin, such as the ciliary zonules of the eye. Mutations in fibrillin-1—the principal structural component of microfibrils—cause Marfan syndrome, a heritable disease with severe aortic, ocular, and skeletal defects. Isolated fibrillin-rich microfibrils have a complex 56 nm beads-on-a-string appearance the molecular basis of their assembly and... 

Rock, M. J., Cain, S., Freeman, L., Morgan, A., Mellody, K, Marson, A., Shutdeworth, C. A., Weiss, A. S., and Kielty, C. M. (2004). Molecular basis of elastic fiber formation Critical interactions and a tropoelastin - fibrillin-l-crosslink. /. Biol. Chem. 279, 23748-23758. 

The fundamental driving force behind the remarkable elastic properties of the elastin polymer is believed to be entropic, where stretching decreases the entropy of the system and elastic recoil is driven by a spontaneous return to maximum entropy. The precise molecular basis for elasticity has not been fully elucidated and a number of models exist. Two main categories of structure-function models have been proposed those in which elastin is considered to be isotropic and devoid of structure, and those which consider elastin to be anisotropic with regions of order (Vrhovski and Weiss, 1998). 

Although good progress has been made in understanding the molecular basis of titin s elasticity, many details remain to be established, such as the... 

Silver FH, Freeman JW, Horvath I, Landis WJ. Molecular basis for elastic energy storage in mineralized tendon. Biomacromol. 2001 2 750-756. 

Rubber is an extraordinary material with a rich history, shaped by a collection of intriguing characters and full of trials, tribulations and triumphs. There is so much good stuff that we devoted two of the chapters in our The Incredible World of Polymers CD to the subject. Here we will discuss the molecular basis of rubber elasticity. 

Most significantly, however, the molecular basis for positive cooperativity and the result of increased functional efficiency in designed elastic-contractile model proteins has been experimentally determined to be the competition for water that occurs between oil-like domains and charged groups constrained to coexist within a protein structure (see immediately below and Chapter 5, section 5.1.7.4). This represents the principal statement of the Mechanistic Assertion. 

Molecular Basis for Defective Elastic Tissue in Environmentally Induced Lung Disease Pulmonary Emphysema... 

D.W. Urry, R.S. Bhatnagar, H. Sugano, K.U. Prasad, and R.S. Rapaka, A Molecular Basis for Defective Elastic Tissue in Environmentally Induced Lung Disease. In Molecular Basis of Environmental Toxicity, R.S. Bhatnagar, Ed., Ann Arbor Scientific Publishers, Inc., Ann Arbor, MI, pp. 515-530, 1980. 

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