Long-period ordering

Figure 3.41. The oI40-AuCu(II) structure. This superstructure contains 10, slightly distorted, tP4-AuCu( I) pseudo-cells. The long-period ordering corresponds to a periodic shift of the structure (every five cells along the orthorhombic Yaxis) by />. (at I c) in the % c plane. The anti-phase domain contains 5 AuCu(I) pseudo-cells.

AljM with M = V, Nb, Ta, and some other phases, e.g. NijV (Bauer, 1939 Vil-lars and Calvert, 1991). The DO22 structure is derived from the close-packed cubic LI 2 structure by the stacking of LI 2 cubes with periodic antiphase boundaries in between, and thus the DO22 structure may be regarded as a tetragonally distorted, long-period ordered, cubic structure (Bauer, 1939 Yamaguchi and Umakoshi, 1990). 

Hui X, Dong W, Chen GL, Yao KF, Formation, microstructure and properties of long-period order structure reinforced Mg-based bulk metallic glass composites , Acta Materialia, 2007 55 907-920. 

Adsorbates can physisorb onto a surface into a shallow potential well, typically 0.25 eV or less [25]. In physisorption, or physical adsorption, the electronic structure of the system is barely perturbed by the interaction, and the physisorbed species are held onto a surface by weak van der Waals forces. This attractive force is due to charge fiuctuations in the surface and adsorbed molecules, such as mutually induced dipole moments. Because of the weak nature of this interaction, the equilibrium distance at which physisorbed molecules reside above a surface is relatively large, of the order of 3 A or so. Physisorbed species can be induced to remain adsorbed for a long period of time if the sample temperature is held sufficiently low. Thus, most studies of physisorption are carried out with the sample cooled by liquid nitrogen or helium. 

We have derived time-reversible, symplectic, and second-order multiple-time-stepping methods for the finite-dimensional QCMD model. Theoretical results for general symplectic methods imply that the methods conserve energy over exponentially long periods of time up to small fluctuations. Furthermore, in the limit m —> 0, the adiabatic invariants corresponding to the underlying Born-Oppenheimer approximation will be preserved as well. Finally, the phase shift observed for symmetric methods with a single update of the classical momenta p per macro-time-step At should be avoided by... 

There is mote than one way to make PV systems cost effective, ie, by making mote efficient and less expensive devices, by stimulating the market toward higher sales in order to justify production volume increases to achieve economies of scale, and by combinations of these options. In any case, modules must operate tehably for long periods of time. 

Stability. In order to have maximum effectiveness over long periods of time, an antioxidant should be stable upon exposure to heat, light, oxygen, water, etc. Many antioxidants, especially in the presence of an impurity when exposed to light and oxygen, are subject to oxidation reactions with the development of colored species. Alkylated diphenyl amines are least susceptible and the -phenylenediamine derivatives the most susceptible to direct oxidation. 

K. Otsuka, T. Ohba, M. Tokonami and C.M. Wayman, New description of long period stacking order... 

In the completion and workover operations, there are long periods when fluid in the hole is not circulated. Fluid suspension and thermal stability should be determined in order to evaluate the necessary circulation frequency. 

Equation 8b is plotted in Fig. 13.14. We see that the concentration of the reactant decreases rapidly at first but then changes more slowly than a first-order reaction with the same initial rate. This slowing down of second-order reactions has important environmental consequences because many pollutants degrade by second-order reactions, they remain at low concentration in the environment for long periods. Equation 8a can be written in the form of a linear equation ... 

From this, it can be seen that the optimum choice of 3D technique depends on the observing strategy appropriate to the particular scientific investigation. However there are other, second-order, considerations to be considered which violate this datacube theorem. These include whether the individual exposures are dominated by photon noise from the background or the detector, and the stability of the instrument and background over a long period of stepped exposures. 

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