Volume profile analysis

A challenging question concerns the feasibility of the application of high-pressure kinetic and thermodynamic techniques in the study of such reactions. Do long-distance electron-transfer processes exhibit a characteristic pressure dependence and to what extent can a volume profile analysis reveal information on the intimate mechanism ... 

SCHEME 7. CO2 catalyzed hydration and dehydration reaction by HCA II based on volume profile analysis. 

The two examples discussed above demonstrate on the one hand how volume profile analysis can contribute toward a better understanding of the underlying reaction mechanisms, and on the other hand how pressure can... 

G. Stochel and R. van Eldik (1999) Coordination Chemistry Reviews, vol. 187, p. 329 - Elucidation of inorganic reaction mechanisms through volume profile analysis . 

The mechanistic interpretation of volume of activation and reaction volume data according to a volume profile analysis cannot be treated in this compilation. However, we would like to direct the readers attention to some interesting papers of general interest to this topic in the following references a method to estimate the intrinsic term in activation and reaction volumes/ the ionic-strength dependence of volumes of activation/ the correction for the compressibility of the solvent/ the role of nonlabile ligands in the interpretation of volumes of activation/ and the theoretical prediction of partial molar volumes and volumes of activation. 

This reaction was followed by a second slower reaction that was not characterized in the report. An analysis of the overall results showed that the influence of steric or electrostatic effects on kinetic parameters is not necessarily minor. The dynamics of binding of NO to the diaqua species is mainly tuned by modulation of electron density on the iron center by the porphyrin macrocycle. A volume profile for NO binding based on values ofAV on and A V 0ff of + 1.5 and + 9.3 cm3/mol, respectively, maybe interpreted as an interchange mechanism for the on reaction, as the Fenl-H20 bond is decidedly stabilized (see Figure 7.15a). The volume of activation for the off reaction indicates a less dissociative mode of activation compared with NO release from other porphyrins. 

Dynamic Sorption of Ink Jet Ink Drops on Commercial Papers. Drying times (t ) and various parameters measured or derived from contact line spreading, profile development and penetration data for the various systems studied are summarized in Table I. A wide variation occured in the values of tj among the various papers studied. The maximum deviations in tdetailed contact line and profile analysis suggest that these deviations result from the structural variability in paper rather than drop-to-drop volume variations. This was substantiated by the marked variations in the final image shape observed among several drops printed on the same paper sample. 

Drops and bubbles are indeed the same mathematical object. However, in marine water studies, the profile analysis of captive (or emerging) bubbles is preferable in respect to the analysis of drops. Actually, from the physical point of view, bubbles exhibit some differences in respect to drops a) diffusion to the air-water interface from a semi-infinite medium (rather than from the small volume confined by the drop) b) limited evaporation c) possibility of observing bubble properties both in quiescent hydrodynamic conditions or in laminar flow regime. Moreover, a captive bubble can be expanded to very large dimensions. 

The goal of a pressure analysis of a chemical reaction is to construct the volume profile, which specifies at least the relative partial molar volumes of the reactants, products, and transition state. Figure 6.1 shows examples of several profiles. Note that the transition state may lie above, below, or in between the reactant and the product states and note that the difference between the forward and backward value of AV must be equal to AU. ... 

Figure 3 contains dynamic data for ff-LG received by three methods the maximum bubble pressure method in the time range 0.001 s to 100 s, the drop volume method for times in the range 5 s to 500 s, and the profile analysis tensiometer PAT l in the time range from 10 s up to several hours. 

The results in Tables III and IV nicely demonstrate the complementarity of the kinetic and thermodynamic data obtained from stopped-flow, UV-vis, electrochemical and density measurements. The resulting picture is consistent and allows a further detailed analysis of the data. The overall reaction volumes determined in four different ways are surprisingly similar and underline the validity of the different methods employed. The volume profiles in Figures 2 and 3 demonstrate the symmetric nature of the intrinsic and solvational reorganization in order to reach the transition state of the electron transfer process. In these systems, the volume profile is controlled by effects on the redox partner of cytochrome c, but this does not necessarily always have to be the case. The location of the transition state on a volume basis will reveal information concerning the early or late nature of the transition state and reveal details of the actual electron transfer route followed. 

For even better results, drop profile analysis can be applied instead of measuring the contact angle directly (axisymmetric drop shape analysis, ASDA Fig. 4.20). This technique extracts experimental drop profiles from video images while slowly increasing or decreasing the droplet volume [42, 43]. The best fit of experimental data with theoretical assumptions based on the Laplace equation of capillarity allows one to calculate the surface/inter-facial tension and subsequently the contact angle. Also droplet radius, droplet volume, and the contact area are computed. ADSA can therefore reveal... 

As mentioned above the oscillating drop or bubble method, based on profile analysis tensiometry, is the most recently developed method to investigate the surface relaxation of soluble adsorption layers. By increasing/decreasing the volume of a pendent drop or bubble, a variety of area changes can be performed, such as step, square pulse, ramp type, trapezoidal, and of course harmonic area changes at low frequencies. 

AES Smallest volume of any analytieal technique, depth profiling analysis Surface may be damaged by the incident electron beam Watts and Wolstenholme... 

Fig. 8 Dynamic surface tension of mixtures between a highly surface-active model suspension and modified starches having the same cationicity, but different degrees of benzylation, DSbn. at a mixing ratio (volume suspensionrvolume starch) of 10 1 surface tension was measured using a profile analysis tensiometer (t = 1,200 s) [67]...

Fig. 8. Drug-induced proteome changes predict for therapeutic resistance. (A) Mice bearing established >300 mm Fo5 (Flerceptin-resistant) and 1282 (Flerceptin-sensitive) tumors were treated with Flerceptin 30 mg/kg i.p. twice a week. Each data point represents mean tumor volume SD (Fo5, = 3 1282, n = 6). (B) Fo5 and 1282 tumors of equivalent size were harvested 24 and 48 h after a single dose of Herceptin i.p. and subjected to mass spectral proteomic profiling analysis. An example of a statistically significant change observed after Herceptin treatment in the 1282 tumors not observed in the Fo5 tumors is shown. The solid line trace (—) represents control, untreated tumors while the dotted line trace ( ) represents Herceptin-treated tumors. (Reprinted with permission from the American Association for Cancer Research from Cancer Research 64 9093-9100, 2004.)...

---