Propagation phase

Campolieti G and Brumer P 1994 Semiclassical propagation phase indices and the initial-value formalism Phys. Rev. A 50 997... 

The step in which the reactive intermediate, in this case A-, is generated is called the initiation step. In the next four equations in the example above, a sequence of two reactions is repeated this is the propagation phase. Chain reactions are characterized by a chain length, which is the number of propagation steps that take place per initiation step. Finally, there are termination steps, which include any reactions that destroy one of the reactive intermediates necessary for the propagation of the chain. Clearly, the greater the frequency of termination steps, the lower the chain length will be. 

Esterbauer et cil. (1992) have studied the in vitro effects of copper on LDL oxidation and have shown that there are three distinct stages in this process. In the first part of the reaction, the rate of oxidation is low and this period is often referred to as the lag phase the lag phase is apparently dependent on the endogenous antioxidant content of the LDL, the lipid hydroperoxide content of the LDL particle and the fatty acid composition. In the second or propagation phase of the reaction, the rate of oxidation is much faster and independent of the initial antioxidant status of the LDL molecule. Ultimately, the termination reactions predominate and suppress the peroxidation process. The extensive studies of Esterbauer et al. have demonstrated the relative importance of the endogenous antioxidants within the LDL molecule in protecting it from oxidative modification. 

The major lipid-soluble antioxidant primarily associated with lipid membranes is a-tocopherol (vitamin E). Circulating a-tocopherol is carried by chylomicrons, LDL and HDL and also has extracellular antioxidant capacities. As a chain-breaking antioxidant, it short circuits the propagation phase of lipid peroxidation because the peroxyl radical will react with a-tocopherol more rapidly than a polyunsaturated ffitty acid (Burton and Traber, 1990). The resulting a-tocopheryl radical reacts with a second peroxyl radical to form an inactive, nonradical complex. In vitro, ascorbate regenerates the tocopheryl radical into its native non-radical form (Burton and Traber, 1990). 

Slemrod, M., 1983, Admissibility criteria for propagating phase boundaries in a van derWaals fluid,drcA. 

FIGURE 9.1 Amplitude and phase profiles of focal fields. Amplitude (a) and (b) phase in the focal xy-plane. Amplitude (c) and phase (d) in the yz-plane. The phase difference below and above the focal plane is a signature of the Gouy phase shift. The propagation phase was subtracted for clarity. Calculations are for a 1.1 NA water immersion lens and the wavelength is 800 nm. In the panels the lateral axis runs from -1.0 xm to 1.0 xm and the axial axis from -3 4m to 3 xm. 

Once the monomer radical has been initiated, high polymer is formed through addition of monomer units to the radical in the propagation phase of the polymerization. Each time a monomer unit is added, the radical transfers to the end of the chain to allow the polymerization to continue ... 

The ideal anticoagulant drug would prevent pathologic thrombosis and limit reperfusion injury, yet allow a normal response to vascular injury and limit bleeding. Theoretically this could be accomplished by preservation of the TF-VIIa initiation phase of the clotting mechanism with attenuation of the secondary intrinsic pathway propagation phase of clot development. At this... 

During this phase, the initiated monomer rapidly adds another monomer to a chain by the addition of a free radical to the double bond of a monomer with the generation of another free radical [196], That is, in the propagation phase, due to the development of the electron transfer process, the resulting movement of the active center down the chain results in the production of the polymer [195],... 

Fatigue Crack Initiation vs. Fatigue Crack Propagation Phase. 118... 

Figure 4 shows results investigations by Sauer and Hara [73], where the crack initiation limit for PMMA is shown in addition to the failure line. Comparing the time period from the beginning of the experiment to crack initiation, it becomes clear that the lifetime is determined by the duration of the crack propagation phase. This is the fundamental assumption of the fracture mechanical description method. 

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