7) Kryszewski, M. and A. Szymanski, Macromol. Rev. 4D, 183 (1970). The density and the energetic situation of local- 8) Bassler, H., Kunststoffe 62, 115 (1972). i; ed levels at the polymer surface and bulk and their 9) Rose, A., Helv. Phys. Acta 29, 199 (1956). occupancy probability of excess electrons or defect- 10) Many, A., Y. Goldstein and N. B. Grover electrons determine the electrostatic charging of Semiconductor Surfaces, 139 (Amsterdam 1971): polymer solids associated with the contact of met- 11) Many, A., N. B. Grover, Y. Goldstein and E. als. Accumulation layers of excesselectrons and de- Harnik, ]. Phys. Chern. Solids 14, ]D 5, 298 (1960). pletion layers of defectelectrons can exist near the 12) Many, A., Y. Goldstein and N. B. Grover polymer surface depending on the electrical potential Semiconductor Surfaces, 185 (Amsterdam 1971): of the contacting metal. These layers are caused by 13) Ryvktn, S. M., Photoelectric Effects in Semi- the difference between the physical states of the poly- conductors, 252 (New York 1964). mer surface and bulk. The energetic situation of the 14) Cholvdry, A. and C. R. Westgate, ]. Phys. D: localized levels is determined by intermolecular inter- Appl. Phys. 7, 713 (1974). actions and therefore it depends on the state of 15) Many, A., Y. Goldstein and N. B. Grover, order of the surface and the bulk. Semiconductor Surfaces, 136 (Amsterdam 1971).

that in all statistical calculations we only have derived most probable i.e. average quantities In this paper the meander model of muscle is proposed (e.g. geometries, forces) a.nd did not care about and treated quantitatively. The geometries of myosin and uninterrupted actin filaments as weIl as of the Z their fluctuations which in principle could also zone in vertebrate striated muscle are derived from be evaluated. thermodynamic equilibrium considerations. Cross- The proposed meander model of muscle is bridges formed by the myosin projections and the actin suitable to explain active as weIl as passive meander folds are considered either to be loose or closed. Mg A TP action enables them to rearrange forces and removes, therefore, the difficulties. cyclically. The closed bridges give rise to a thermodynamic inherent in Huxleys sliding filament model. . contractive force on the actin filament. Also passive and We cannot exclude, however, that there is a active stress-strain behaviour (under isometrie condi- small contribution to the passive elastic be- tions) agree with experiment. haviour from elements (e.g. membranes) in Zusammenfassung parallel to the sliding filament system.

70 DegreesC unterhalb des Einfrierbereichs wegen x 0 is applied to experimental data of the specific volume of water, werden aufgrund von speziellen Modellvor- sulfur, mercury and polystyrene, ex is the expansion stellungen von Gibbs und Dimarzio ent- coefficient at constant pressure, u the isothermal wickelt, wobei die Autoren fUr T

(Sonderausgabe aus Kolloid-Zeitschrift & Zeitschrift fur Polymere, Band 241)