Spontaneous transformations description

Our own experimental data clearly indicate that TATP is much less sensitive. The reasons why such a large scatter is reported in the literature is not clear, but may relate to one or more of the following (a) tendency of TATP to recrystaUize forming large crystals, (b) spontaneous transformation of TATP to other peroxides, (c) the type of acid used in preparation, (d) crystal size, or (e) experimental setup. Most of the authors who measured the sensitivity of TATP generally did not fully describe the measured samples in terms of shape, size, age, storage temperature, and preparation route. Published values of impact sensitivity are summarized in Fig. 2.15 irrespective of the previously mentioned incomplete description. 

After providing a brief description of zeolitic structures, we discuss the hierarchy of structures of open-framework metal phosphates ranging from zerodimensional monomeric units and one-dimensional linear chains to complex three-dimensional structures. Aspects related to the likely pathways involved in the assemblage of these fascinating structures are examined, pointing out how the formation of the complex three-dimensional structures of open-framework metal phosphates involves the transformation and assembly of smaller units. Besides the role of the four-membered monomer, the amine phosphate route to the formation of the three-dimensional structures is discussed. The last step in the formation of these structures from preformed units of the desired structure is likely to be spontaneous. Our recent studies of open-framework metal oxalates have shown the presence of a hierarchy of structures. Reactions of amine oxalates with metal ions yield members of the oxalate family with differing complexity. 

The description of structure in complex chemical systems necessarily involves a hierarchical approach we first analyse microstructure (at the atomic level), then mesostructure (the molecular level) and so on. This approach is essential in many biological systems, since self-assembly in the formation of biological structures often takes place at many levels. This phenomenon is particularly pronounced in the complex structures formed by amphiphilic proteins that spontaneously associate in water. For example myosin molecules associate into thick threads in an aqueous solution. Actin can be transformed in a similar way from a monomeric molecular solution into helical double strands by adjusting the pH and ionic strength of the aqueous medium. The superstructure in muscle represents a higher level of organisation of such threads into an arrangement of infinite two-dimensional periodicity. 

Unlike classical quantum mechanics, the spontaneous processes of the damped oscillator are irreversible, so its quantum mechanical description needs changes to some instruments of classical quantum mechanics. To do this, we use the Heisenberg picture of quantum processes. In this picture, the observables are time-dependent linear Hermitian operators, and the state vector of the system is time independent. Using the terminology introduced in the first part, the infinitesimal time transformation of the Hermitian operator could happen in two ways ... 

Four principal theories describing the transformation of the isotropic fluid into a spontaneously organized nematic fluid, the I N transition, have been developed (1) Onsager s density expansion of the free energy of anisometric particles, (2) Rory s estimate of the insertion probability for a rod-like (multisite) solute into a lattice, (3) Maier and Saupe s construction of apotential of mean torque experienced by mesogens (or solutes) in a nematic environment, and (4) de Gennes transposition of Landau theory to the I N transition. We briefly examine each of these in reverse chronological order because each is relevant to more-recent theoretical descriptions of polymer mesophases. 

The pair correlations between atoms or sites in a molecular fluid pertain to the microscopic spontaneous fluctuations that occur in a macrosCOpically homogeneous fluid. Under certain circumstances, these fluctuations conspire collectively or in concert to form ordered phases such as crystals. The description of these transformations of phase is beyond the scope of the linear (i.e., Gaussian) theory we have outlined thus far. The incorporation of nonlinearities is the subject we turn to... 

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