symmetrical dinitrogen tetroxide, ONON0 2 , is to some extent chemically analogous to dinitrogen pentoxide, 02NON0 2. The latter compound can be deposited in covalent form 27,28 from the vapor phase onto a cold (T"'900K) window. It is transformed to the ionic form upon warming to 195°K.27,28 Also, in highly polar solvents it exists in the ionic form. The discussion of the chemical mechanism of formation of nitrosonium nitrate will be presented elsewhere

SynopsisThe kinetics of biopolymerizat.ion on nucleic acid templates is discussed. The model introduced allows for the simultaneous synthesis of several chains, of a given type, on a common template, e.g., the polyribosome situation. Each growth center [growing chain end plus enzyme(s)] moves one template site at a time, but blocks L adjacent sites.Solutions are found for the probability nj(t) that a template has a growing center t.hat occupies the sites j -L + I, . . . , j a t time t. Two special sets of solutions are considered, the uniform-density solutions, for which nj(t) = n, and the more general steadystate solutions, for which dnj(t)/dt = 0. I n the uniform-density case, there is an upper bound to the rauge of rates of polymerization that can occur. Corresponding to this maximum rate, there is one uniform solution. For a polymerization rate less than this maximum, there are two uniform solutions that give the same rate. In the steady-state case, only 1 , = 1 is discussed. For a steady-state polymerization rate less than the maximum uniform-density rate, the steadystate solutions consist of either one or two regions of nearly uniform density, with the density value(s) assumed in the uniform region(s) being either or both of the uniform-density solutions corresponding to that polymerization rate. For a steady-state polymerization rate eqital to or slightly larger than the maximum uniform-density rate, the steady-state solutions are nearly uniform to the single uniform-density solution for the maximum rate. The boundary conditions (rate of initiation and rate of release of completed chains from the template) govern the choice among the possible solutions, i.e., determine the region(s) of uniformity and the valu4s) assumed in the uniform region(s).

The thermodynamic properties of amorphous phases of linear molecular chains are obtained from statistical mechanics by means of a form of the quasi-lattice theory which allows for chain stiffness and the variation of volume with temperature. A second-order transition is predicted for these systems. This second-order transition has all the qualitative features of the glass transition observed experimentally. It occurs at a temperature which is an increasing function of both chain stiffness and chain length and a decreasing function of free volume. The molecular ``relaxation times'' are shown to increase rapidly as the second-order transition temperature is approached from above. To permit quantitative application of the theory and determine the relationship between the second-order transition and the glass transition observed in ``slow'' experiments these two transitions are tentatively identified. By this means quantitative predictions are made concerning the variations of (1) glass temperature with molecular weight, (2) volume with temperature, (3) volume with molecular weight, (4) volume at the glass temperature with the glass temperature for various molecular weights of the same polymer, (5) specific heat vs temperature, and (6) glass temperature with mole fraction of low-molecular weight solvent, since extensive experimental results are available for these properties. These and other theoretical predictions are found to be in excellent agreement with the experimental results.