Statics or Dynamics

Since a molecular dynamics simulation of a lattice provides a description not only of the structure but also of its behavior in time, it could be assumed that MD has more to offer than static simulations as an investigative method for the conductive polymers. But with a time step At = 1 s (or even lO s, which limits 

On the other hand since the dynamics may be simulated at any chosen temperature or range of temperatures (rather than at 0 K, as is formally the case in static simulations), MD results may be processed to provide many experimentally interesting quantities—diffusion parameters, thermodynamic functions, radial distribution, and correlation functions—the last of which may be related to measured relaxation data. As a result the two techniques should be regarded as complementary. With the current rapid expansion in computing power, it is likely that at least some of the limiting caveats described will soon be eliminated. 

---

The wurt2ite form differs only slightly from the cubic form, but it is not quite as stable. It is most easily obtained by static or dynamic compression of hBN or rBN at high pressures (17). In the presence of a Hquid catalyst at high pressures, the wurt2ite form changes rapidly to the cubic form. The change occurs more slowly without a catalyst above 6 GPa (60 kbar) (18). 

In this process, diamond forms from graphite without a catalyst. The refractory nature of carbon demands a fairly high temperature (2500—3000 K) for sufficient atomic mobiUty for the transformation, and the high temperature in turn demands a high pressure (above 12 GPa 120 kbar) for diamond stabihty. The combination of high temperature and pressure may be achieved statically or dynamically. During the course of experimentation on this process a new form of diamond with a hexagonal (wurtzitic) stmcture was discovered (25). 

Equilibrium moisture content of a hygroscopic material may be determined in a number of ways, the only requirement being a source of constant-temperature and constant-humidity air. Determination may be made under static or dynamic conditions, although the latter case is preferred. A simple static procedure is to place a number of samples in ordinaiy laboratoiy desiccators containing sulfuric acid solutions of known concentrations which produce atmospheres of known relative humidity. The sample in each desiccator is weighed periodically until a constant weight is obtained. Moisture content at this final weight represents the equilibrium moisture content for the particular conditions. 

Generally, the models used for simulation of living polymers can be divided roughly into two classes, focused on static or dynamic properties of the LP or GM. The static models are mainly designed to study equilibrium conformational properties of the polymer chains, critical behavior at the polymerization transition, and molecular weight distribution... 

Tautomeric compounds as guest included in a host (static or dynamic)... 

Equation 4-9 remains unchanged by the initiation of hook motion (i.e., the force in the dead line is the same under static or dynamic conditions). The mechanical advantage (ma) under dynamic conditions is... 

The method of establishing and using alert/alarm limits varies depending on the particular vibration monitoring system that you select. Normally these systems will use either static or dynamic limits to monitor, trend and alarm measured vibration. We will not attempt to define the different dynamic methods of monitoring vibration severity in this book. We will however provide a guideline for the maximum limits that should be considered acceptable for most plant mechanical equipment. 

The DPA moiety is less active in forming the CT complex with viologens than the pyrene moiety e.g., for PMAvDPA the KCT values with MV2+ and SPV are 1.3 x 103 M 1 and almost zero, respectively, at pH 8-9 [60, 77], whereas for PMAvPY they are 7.8 xlO4 and 6.3 x 102 M, respectively, at pH 11 [77]. Therefore, the polymer-bound pyrene system undergoes much more static quenching than the polymer-bound DPA system. As will be discussed in Chapter 6, it is very important for charge separation whether the fluorescence quenching is static or dynamic. 

The subject of strength is much more complex than stiffness, since so many different types exist short or long term, static or dynamic, etc. (Chapter 2). Some strength aspects are interrelated with those of toughness. The crystallinity of TPs is important for their short term yield strength. Unless the... 

The dynamic scaling argument supposes that when the geometrical parameters of the chain (i.e. N and lp) are changed from N into N/A and lp into lpV, any physical quantity (A), either static or dynamic, related to the molecular size will be transformed into XXA. The parameter v is the exponent in Eq. (9) and is equal to 1/2 in 0-solvent and 3/5 in good solvent. 

Two system-dependent interpretative pictures have been proposed to rationalize this percolative behavior. One attributes percolation to the formation of a bicontinuous structure [270,271], and the other it to the formation of very large, transient aggregates of reversed micelles [249,263,272], In both cases, percolation leads to the formation of a network (static or dynamic) extending over all the system and able to enhance mass, momentum, and charge transport through the system. This network could arise from an increase in the intermicellar interactions or for topological reasons. Then all the variations of external parameters, such as temperature and micellar concentration leading to an extensive intermicellar connectivity, are expected to induce percolation [273]. 

Operations Op can be seen as operators that can take on a logical integer, analytic (static or dynamic), or hybrid form. With each operation we have associated an integer-valued variable, aj t), which determines the discrete state that the operator takes on with time. 

The quality of the ) states has been tested through their energy and also their transition moment. Moreover from the natural orbitals and Mulliken populations analysis, we have determined the predominant electronic configuration of each ) state and its Rydberg character. Such an analysis is particularly interesting since it explains the contribution of each ) to the calculation of the static or dynamic polarizability it allows a better understanding in the case of the CO molecule the difficulty of the calculation and the wide range of published values for the parallel component while the computation of the perpendicular component is easier. In effect in the case of CO ... 

Component Transport Transport through membranes can be considered as mass transfer in series (1) transport through a polarization layer above the membrane that may include static or dynamic cake layers, (2) partitioning between the upstream polarization layer and membrane phases at the membrane surface, (3) transport through the membrane, and (4) partitioning between the membrane and downstream fluid. 

Differentiation of SPE methods can be made according to the following criteria (i) the type of sorbent (ii) the mode of performing SPE (static or dynamic) (iii) (in case of dynamic SPE) off-line (cartridges) or on-line ... 

In Chapter 3 the steady-state hydrodynamic aspects of two-phase flow were discussed and reference was made to their potential for instabilities. The instability of a system may be either static or dynamic. A flow is subject to a static instability if, when the flow conditions change by a small step from the original steady-state ones, another steady state is not possible in the vicinity of the original state. The cause of the phenomenon lies in the steady-state laws hence, the threshold of the instability can be predicted only by using steady-state laws. A static instability can lead either to a different steady-state condition or to a periodic behavior (Boure et al., 1973). A flow is subject to a dynamic instability when the inertia and other feedback effects have an essential part in the process. The system behaves like a servomechanism, and knowledge of the steady-state laws is not sufficient even for the threshold prediction. The steady-state may be a solution of the equations of the system, but is not the only solution. The above-mentioned fluctuations in a steady flow may be sufficient to start the instability. Three conditions are required for a system to possess a potential for oscillating instabilities ... 

It can be said that acoustic and hydrodynamic cavitation are the result of the tensions prevailing in a liquid, while optic and particle cavitation are the consequence of the local deposition of energy. The classification scheme for the phenomena of cavitation has been shown schematically in Fig. 2.1. Once the cavities are generated, subsequent expansion of the minute cavity may be achieved by reducing the ambient pressure using static or dynamic means. The surrounding... 

The values of these relevancy coefficients can be fixed depending on the practical chemical problem using static or dynamic models (Matherny and Eckschlager [1996] Eckschlager and Stepanek [1985] Eckschlager and Danzer [1994]). 

Either static or dynamic headspace gas GC is used to examine residual solvents in polymeric materials. Figure 43 shows the complex volatiles liberated from a printed multi-layer salad wrap, heated at 300°C under nitrogen. 

Being a very sensitive quantity, however, the relative energy part of the modulus is different for some of the samples, if calculated from static or dynamic data, respectively. (For the calculation method, compare ref. 2J3, K ) Table III gives the values for the relative energy part. ore(j u/ored the ener9Y part calculated from stress-strain measurements Gy/G is the corresponding number obtained from dynamic data at 0.5 Hz. 

The commercialization of inexpensive robust LED and laser diode sources down to the uv region (370 nm) and cheaper fast electronics has boosted the application of luminescence lifetime-based sensors, using both the pump-and-probe and phase-sensitive techniques. The latter has found wider application in marketed optosensors since cheaper and more simple acquisition and data processing electronics are required due to the limited bandwidth of the sinusoidal tone(s) used for the luminophore excitation. Advantages of luminescence lifetime sensing also include the linearity of the Stem-Volmer plot, regardless the static or dynamic nature of the quenching mechanism (equation 10) ... 

It must be also considered that the reaction rates of different thermal processes which can occur simultaneously are influenced by the treatment conditions (temperature, heating rate, pressure, static or dynamic atmosphere). This will affect the relative quantities of the products formed and in some cases also their nature, when recombination reactions give rise to secondary degradation products. On account of its sensitivity and resolution power Py-GC/MS will also provide useful information on minor components present in a material, including low molecular weight additives and pigments. 

---