Transitions features

Some complexes show a strong interdependence between crystal structure and spin-transition features. In the series of compounds [Fe(Rtz)6](BF4)2 (Rtz = 1-alkyltetrazole) the spin crossover behavior varies with the substituent R and is strongly influenced by cooperative effects. For example, the propyl derivative shows a quantitative spin transition, which is accompanied by a first-order crystallographic phase transition in the methyl and ethyl derivatives the Fe11 complexes occupy two nonequivalent lattice sites, only one of which shows a thermal spin transition.29... 

In the case of phase transitions or other structural changes, the frequencies, the intensities, and the halfwidths of the water bands, especially those of the stretching and Ubrational modes, as well as the temperature derivatives of these values change discon-tinuously. Hence, even very small phase transition features can be observed, such as disorder or small distortions of the coordinations spheres, often not detectable by X-ray methods, etc. 

The angles of branching, the diameter and lengths of different elements of the airways, and the pulmonary air spaces must be visualized in an arbitrary and oversimplified form to make practical use of anatomic data. Some of the details ofthe divisions of the respiratory system that have been assumed by Landahl [53] and the anatomic flow rate and transitional features in these areas are shown in Table 5. 

The modification with allylamine could be expected to not only reduce the surface oxidation rate but also maintain an efficient electronic transition feature that facilitates blue emission. The optical properties show significant size dependence due to the quantum confinement effect. The increase in the number of allylamine molecules could only result in a slight red shift of emission spectra. 

In a DSC scan, the difference of energy input (heat flow) into a sample and into a reference material is plotted as a function of temperature. In a plot of heat flow vs. temperature, endothermic minima correspond to desolvation of solvates or phase transitions of polymorphs, and exothermic maxima correspond to crystallization or decomposition. Integration over the area of a transition feature yields the associated transition enthalpy. 

The effectiveness of the modelling approach described in the previous Sections is demonstrated using a case-study in the mass transit domain, whose assets are vulnerable to several threats, including terrorist attacks. Therefore, surveillance systems for mass transit feature a growing number of heterogeneous sensing devices. In such a context, the quantitative evaluation of the PPS effectiveness is very important to design robust surveillance systems and to reduce the overall risk associated to the considered threats. 

Alternatively, appearance of the failure surface is indicative of the nature of fracture and may be used in transition temperature determinations. For ductile fracture, this surface appears fibrous or dull (or of shear character), as in the steel specimen of Figure 8.14, which was tested at 79°C. Conversely, totally brittle surfaces have a granular (shiny) texture (or cleavage character) (the —59°C specimen in Figure 8.14). Over the ductile-to-brittle transition, features of both types will exist (in Figure 8.14, displayed by specimens tested at -12°C, 4°C, 16°C, and 24°C). Frequently, the percent shear fracture is plotted as a function of temperature-curve B in Figure 8.13. 

It is a nice example because, despite the simplicity and limitations of the model, it shows transition features that are very characteristic for heteropolymer folding and apply, in similar form, to realistic proteins as well. In the following, we will discuss the transition behavior in detail by means of statistical canonical analysis, which will give us some general insight into the interpretation of conformational transitions of proteins as finite-size variants of structural phase transitions. 

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