Intrinsic behavior

Early in the history of crystal dislocations, the lack of resistance to motion in pure metal-like crystals was provided by the Bragg bubble model, although it was not taken seriously. By adjusting the size of the bubbles in a raft, it was found that the elastic behavior of the raft could be made comparable with that of a selected metal such as copper (Bragg and Lomer, 1949). In such a raft, it was further found that, as expected, the force needed to form a dislocation is large. However, the force needed to move a bubble is too small to measure. 

At roughly the same time, Peierls (1940), and Nabarro (1947) developed a two-dimensional model of a dislocation in a simple square crystal structure. This model indicated that a small, but finite, amount of energy is needed to 

Chemistry and Physics of Mechanical Hardness, by John J. Gilman Copyright 2009 John Wiley Sons, Inc. 

As early as 1938, internal friction in vibrating zinc crystals was observed at strain amplitudes as small as 10The friction was attributed (with good cause) to dislocation motion (Read, 1938). This strongly indicated that the Peierls model could not be accepted as being quantitative. 

Intrinsic resistance to dislocation motion can be measured in either of two ways direct measurements of individual dislocation velocities (Vreeland and Jassby, 1973) or by measurements of internal friction (Granato, 1968). In both cases, for pure simple metals there is little or no static barrier to motion. As a result of viscosity there is dynamic resistance, but the viscous drag coefficient is very small (10 to 10 Poise). This is only 0.1 to 1 percent of the viscosity of water (at STP) and about 1 percent of the viscosity of liquid metals at their 

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These data show clearly that that the intrinsic behavior in pure metals is visco-elastic with the velocity proportional to the applied stress (Newtonian viscosity). Although there is a large literature that speaks of a quasi-static Peierls-Nabarro stress, this is a fiction, probably resulting from studying of insufficiently pure metals. 

The expected Arrhenius plot for cation self-diffusion in KC1 doped with Ca++ is shown in Fig. 8.13. The two-part curve reflects the intrinsic behavior at high temperatures and extrinsic behavior at low temperatures. 

Recent investigations have revealed that the intrinsic behavior of RB28.5C4 is also n-type (Mori et al., 2008a). Very small inclusions of boron carbon "B4C" can cause the p-type behavior previously observed in some samples (Mori and Nishimura, 2006). The origin of the striking n-type behavior observed in the homologous R-B-C(N) compounds is not completely resolved yet but indicated to pertain to the two-dimensional rare earth layers (Mori et al., 2008a). 

Alkaline, alkaline earth metals and aluminum are naturally covered with anodic films. The removal of these native films, even in the best glove box atmosphere, exposes the fresh metal to reactive atmospheric contaminants at a high enough concentration and quickly cover the metal with new surface films. As discussed above, even the glove box atmosphere of an inert gas containing atmospheric components at the ppm level should be considered as being quite reactive to active metals such as lithium. Therefore, anyone intending to study the intrinsic behavior of active metal electrodes in solution must prepare a fresh electrode surface in solution. 

Ongoing investigations into the chemistry of porous silicon surfaces seek to develop methods for the preparation of chemically functional interfaces that protect the underlying silicon nanocrystallites from degradation without changing or annihilating their intrinsic behavior. The native, hydride-terminated surface is only metastable under ambient conditions and oxidation of freshly prepared porous silicon commences within minutes when exposed to air. While surface oxide can suitably passivate the nanocrystalline silicon and stabilize its photoluminescence, the electrically insulating and structurally defective character of this oxide layer... 

As in the cases of silica gel and silica-alumina, H atoms can be detected on alumina at low temperatures after irradiation (75). Since the alumina lattice is almost always partly terminated by OH groups, and since extra adsorbed water is difficult to remove, the intrinsic behavior of the bulk oxide is likely to be accompanied by radiolytic effects in the surface layer. The H atoms are one evidence of this. 

It remains to be determined whether SR 141716-induced behaviors are due to inverse agonist activity, blockade of endogenous cannabinoid tone, or noncannabinoid sites of action. However, these intrinsic behavioral effects of SR 141716 do not occur universally. Moreover, the magnitude of SR 141716-induced head shakes and paw tremors in naive animals is generally significantly less than that found in... 

In vivo capsule viability screen. The intrinsic behavior of the cells, diffusion of nutrients and cofactors, and immunogenicity all affect the viability and function of the cells in capsules. Multiple capsule configurations and cell matrix membrane combinations were tested. The combination of cell ECM scaffold was encapsulated with different membranes and capsules were implanted into CNS and ocular sites (such as rat ventricle, rabbit eye, dog eye, pig eye, and sheep intrathecal space). The optimal cell-matrix membrane combinations that show longevity and functional stability in vivo were chosen for further development. 

In general, it appears that the results on clusters indicate that their intrinsic behavior is antipathetic. It is probably best explained by electronic factors. 

The behavior shown in Fig. 7.3 is typical of many ceramics and indicates a transition from intrinsic behavior at higher temperatures to extrinsic behavior at lower temperatures. In other words, at higher temperatures Eq. (7.20) applies and the slope of the line equals AH /k- AHs/2k. At lower temperatures Eq. (7.21) applies and the slope of the line is simply equal to AHlJk. Calculating... 

The best examples of a transition from extrinsic to intrinsic behavior are observed in data from oxides (e.g. AI2O3, MgO, FeO) reacted with a gas phase, O2 or CO2. 

Intrinsic kinetics of the immobilized enzyme represents its proper behavior and corresponds to that observed in the absence of partition and mass transfer limitations of the reacting species. This kinetic behavior and the corresponding kinetic parameters are not directly measurable for an immobilized enzyme, except in special conditions where these effects are purposely avoided. Even if the intrinsic behavior could be revealed, it may differ from that of the free enzyme counterpart because of conformational changes. 

For Pm, which conveys the intrinsic behavior of the material, we have chosen values found in publications, values which concern the electric resistivity of tin dioxide under vacuum at 500°C. 

Corrstrained yams in the fabric or other textile stractures reveal mechanical responses, which are different in compare with the free yams. Therefore, their intrinsic behavior would not be displayed perfectly. This is actually the reason of representation of Equations (13) and (15). Table 3 reveals fabric modulus along the warp direction the modiCbd warp yams modulns the spring stiffness constarrt, and the equivalent spring stiffness constant for the weft yam of each fabric. 

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