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Temperature effects hardness

The melting temperature is almost independent of pressure, making the boundary line between solid and liquid nearly vertical. Qualitatively, this is because pressure has hardly any effect on the compact liquid and solid phases. [Pg.808]

Crystal stmcture prediction by computer has made great steps forward in the last 10 years, with progress toward consistent success in blindfold tests. Fundamental uncertainties still remain, due to the unknown role of nucleation kinetics and to the neglect of temperature effects in the calculations. Success or failure still depends to some extent on hardly predictable factors and on the extent to which the experimental polymorph screening has been carried out. Presently, some of the best computational tools are not yet available to the general community of solid state scientists, being implemented in commercial, strictly copyrighted software. [Pg.30]

Spiering et al. (1982) have developed a model where the high-spin and low-spin states of the complex are treated as hard spheres of volume and respectively and the crystal is taken as an isotropic elastic medium characterized by bulk modulus and Poisson constant. The complex is regarded as an inelastic inclusion embedded in spherical volume V. The decrease in the elastic self-energy of the incompressible sphere in an expanding crystal leads to a deviation of the high-spin fraction from the Boltzmann population. Pressure and temperature effects on spin-state transitions in Fe(II) complexes have been explained based on such models (Usha et al., 1985). [Pg.203]

These are useful insights, but they should be kept in perspective. This particular study did not take into account other important variables such as temperature and water hardness. The effects produced by these other independent variables can be handled separately in other studies, and their respective contour maps generated. These could also be used as factors in calculating the "Performance" variable. [Pg.96]

The small effect of these tsf substitutions on the first kinetic phase for thermal unfolding explains why they have hardly any effect on the melting temperature. Unfolding of the N-terminal region of the molecule is the initiation step for thermal denaturation of this protein. The apparent Tm measured by microcalorimetry could be defined by this step. Given their location in the central region of the chain, it is not surprising that the tsf mutant proteins affect the second step but not the first. [Pg.129]

The temperature feedback mechanisms provide a link between the reactor s neutronics and its coolant systems independent of any action of the control system. The size and relative importance of the temperature effects will vary from reactor to reactor, but designers work hard to ensure that there is an overall negative coefficient of reactivity with temperature, which provides for automatic limiting or mitigation of temperature excursions. Some important temperature feedback mechanisms are listed below ... [Pg.280]

Practically, the hard core effects of quantum origin do not depend on temperature. On the contrary, the effects of the van der Waals attractive forces, which are softer and have a longer range, increase when temperature diminishes. Concurrently, the contribution of the entropy to the free energy of the system decreases. [Pg.650]

Thus, if we take the packing fraction of the glass transition in the hard-sphere model as a reference, a straightforward prediction of the glass transition volume in real systems based on a complete neglect of temperature effects can be regarded as a perturbation treatment of zeroth order. This... [Pg.423]

The same is true of the trichloroacetic acid test (10 ml at 55% per 100 ml of wine). The mixture is heated in a waterbath at 100°C for 2 mn and turbidity is observed after 15 min at room temperature. This test is hardly more effective than the Bentotest if the addition of excessive quantities of bentonite to wine is to be avoided. [Pg.131]

Several representations of factor effects (effect graphic effects, normal [dot. half-normal plot, etc.) permit us to determine the influence of the factors studied. Wc can see that factors X, Xj, X are the only inHuent factors on the variation of the yield (Fig. 10-12). and the factors X, and Xj have hardly any effect. An increase of the solution B addition temperature (Xi) from 25 C to 45 C entails a diminution of the yield. [Pg.496]

Below 1000°C, Fig. 10 displays a similar temperature effect on the hardness of single and polycrystalline AI2O3. The one difference is that at room temperature... [Pg.200]

For PPI dendrimers, diffusivity versus temperature studies indicated that the dendrimers behave as soft spheres and that only at high generations (fourth and fifth generations) there is a pronounced temperature effect on the radius, resulting from the lower quality of the solvent (methanol) at this temperature and a more hard sphere behavior. ... [Pg.134]


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See also in sourсe #XX -- [ Pg.52 , Pg.53 ]




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