Interpretation of experimental results

Describing and understanding a phenomenon by establishing the relationships between the parameters involved is the basis of a scientific reasoning that leads to the modeling of a process. To obtain such a model, it is important to layout certain information relative to the process, using various experimental results. 

The results obtained, using several complementary experimental technologies, are the primaiy source of information. The nature of this information involves  

Using this information, it becomes necessary to imagine one or more reaction processes which are defined by several basic steps. 

These reaction processes will enable ns to ejqness the equilibrium conditions and the rate which will be used to establish relations between the parameters concerned. 

The variation laws of these parameters are sometimes governed by mathematical laws simple enough to be used directly. 

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Molecular dynamics simulations provide information about the motion of molecules, which facilitates the interpretation of experimental results and allows the statistically meaningful sampling of (thermodynamic) data. 

Cook has suggested that colchicine itself may contain the 7-membered ring B and Dewar has proposed for the alkaloid formula (XV) with (XVfl) as a resonance form, mainly on the ground that the third ring (C) in colchicine resembles in some of its reactions, stipitatic acid and presents similar difficulty in interpretation of experimental results. 

While the few examples quoted provide some general guidance as to the behaviour of nickel-rich materials in contact with molten metals and salts, it cannot be over-emphasised that such behaviour can be very considerably modified by the presence of very small amounts of contaminants in the liquid media (see Sections 2.9 and 2.10). The effect of very small contents of sodium chloride on the corrosion of nickel-base alloys by sodium sulphate has been referred to previously and other reported examples involving trace amounts, particularly of gaseous impurities, underline the need for great care in interpretation of experimental results. 

The present review deals with polymerization systems where the furan ring is present in the monomer(s) either as the reactive entity or as a side group to the function responsible for the growth. It covers, therefore, a wide variety of situations, many of them not yet fully understood. In fact, as will become apparent later, there is still a great deal of controversy about the interpretation of experimental results obtained with most of these systems and sometimes even disagreement among authors as to the data obtained. Particular emphasis has therefore been placed in this review on a critical reinterpretation of previous work in view of the recent experience gathered by... 

A kinetic model which accounts for a multiplicity of active centres on supported catalysts has recently been developed. Computer simulations have been used to mechanistically validate the model and examine the effects on Its parameters by varying the nature of the distrlbultons, the order of deactivation, and the number of site types. The model adequately represents both first and second order deactivating polymerizations. Simulation results have been used to assist the interpretation of experimental results for the MgCl /EB/TlCl /TEA catalyst suggesting that... 

Ruzic [278 ] considered the theoretical aspects of the direct titration of copper in seawaters and the information this technique provides regarding copper speciation. The method is based on a graph of the ratio between the free and bound metal concentration versus the free metal concentration. The application of this method, which is based on a 1 1 complex formation model, is discussed with respect to trace metal speciation in natural waters. Procedures for interpretation of experimental results are proposed for those cases in which two types of complexes with different conditional stability constants are formed, or om which the metal is adsorbed on colloidal particles. The advantages of the method in comparison with earlier methods are presented theoretically and illustrated with some experiments on copper (II) in seawater. The limitations of the method are also discussed. 

To give a full interpretation of experimental results obtained in this work, we have to note that the inhomogeneity of the surface pressure at the air/water interface is one of the most important factors giving rise to the characteristic features in the n-A curves. 

Even though the effect of moisture on the anode kinetics is well known, interpretation of experimental results on the effect of moisture can be tricky. As Nakagawa et al. [52] pointed out, the measurement of the total cell impedance under the OCV condition is not convincing since the reduction of polarization could as well be due to the availability of H20 for the cathodic reaction. In addition, the measurement of cell performance under the constant voltage or constant current conditions may also lead to wrong conclusions about the effect of water, because the addition of H20 will... 

This chapter has shown many examples of the use of CALPHAD methods, ranging from an unusual application in a binary system, through complex equilibrium calculations to calculations for 10-component alloy systems. In all cases the use of CALPHAD methods has enhanced the understanding of processes, clearly defined alloy behaviour and provided vital information for other models, etc. It is also clear that equilibrium calculations can be used in many different areas and under a surprising number of different conditions. For numerous reasons, modelling will never completely replace experimental measurement. However, die quantitative verification of the accuracy of CALPHAD calculations now means that they can be seriously considered as an information source which can be used as an alternative to experimental measurement in a number of areas and can also enhance interpretation of experimental results. 

Ring currents cannot be directly determined by experimental methods. However, comparison of experimental values of magnetic susceptibilities and their exaltations and anisotropies as well as of H-NMR chemical shifts with the respective data calculated from the ring current model points to the adequacy of this model for the interpretation of experimental results. The magnetic susceptibility associated with the ring current / (83BCJ1853), known as the London susceptibility, is given by... 

Good science has always mandated the use of high-quality, disease-free animals to reduce extraneous factors that might complicate the interpretation of experimental results. 

Working on the complexation of PAA [31] and PMAA [32-34] with PEO mon-osubstituted with a variety of hydrophobic groups, Baranovsky et al. [31 ] found that the groups attached to PEO strongly enhanced the stability of both PAA/ PEO and PMAA/PEO complexes, and pointed out that when complexation is examined using a fluorescently labeled component, the stabilizing effect of the hydrophobic fluorescent probes on complexation has to be fully taken into account for the interpretation of experimental results. 

The results from molecular orbital calculations can be divided into two general categories, dealing with energy and electronic populations. The wealth of information that can be obtained is illustrated in Figure 1 (17). Such data are useful in the interpretation of experimental results, and the prediction of the course of novel reactions. 

Even though these approaches are powerful methods for determining functional sites on proteins, they are limited if not coupled with some form of structural determination. As Figure 2 illustrates, molecular biology and synthetic peptide/antibody approaches are not only interdependent, they are tied in with structural determination. Structural determination methods can take many forms, from the classic x-ray crystallography and NMR for three-dimensional determination, to two-dimensional methods such as circular dichroism and Fourier Transformed Infrared Spectroscopy, to predictive methods and modeling. A structural analysis is crucial to the interpretation of experimental results obtained from mutational and synthetic peptide/antibody techniques. 

Equations (36)—(39), obtained for the one-dimensional model, have proved to be quite useful and have been frequently used for the interpretation of experimental results. The exact form of the relation between the averaged probability of the reaction and the reaction rate constant k depends on the type of reaction. For monomolecular reactions, k = vP where v = 1013-... 

Intermolecular electron transfer plays an important role in the operation of biological systems. For example, electron transfer from one biological molecule to another is the primary act of energy conversion in the processes of respiration and photosynthesis. Despite a large number of works dedicated to the study of intermolecular electron transfer in biological systems, the mechanisms of these reactions have been insufficiently elucidated. This is due to great difficulties in the interpretation of experimental results which are in their turn explained by the very intricate structure of biological systems. 

Ab initio calculations of 29Si and 13C NMR chemical shielding tensors have been used as an aid in the interpretation of experimental results aimed at elucidating the role of alkoxyalkylsilanes as external electron donors in Ziegler-Natta catalysis of propene. The results support a model in which dialkoxydialkylsilanes are loosely attached to two adjacent magnesium ions on the surface of magnesium chloride, but trialkoxyalkylsilanes are attached primarily by only one magnesium ion. 

If molecular mechanics is to be a valid modeling tool for the design of new compound and the interpretation of experimental results, the compounds under consideration must belong to a class for which the molecular mechanics model is well defined. In other words, the accuracy of the results obtained depends critically on the parameterization of the force field and how this has been obtained (Fig. 5.1). 

The second reaction represents the formation of a higher oxygen-containing phase, possibly at dislocations. The local formation of such traces of CuO, always a possibility when working with Cu/Cu20 preparations at around 200-400° K., introduces uncertainty into the interpretation of experimental results. 

Since both reversible and irreversible processes are influenced in distinct ways by temperature and water activity, the first step of a humid aging study consists of searching for the conditions (T, RH, sample thickness) in which both phenomena can be clearly decoupled, as in Figs 14. lc and d. The interpretation of experimental results and the modeling of the kinetics of property changes would be difficult or even impossible if physical characteristics such as ar d (or better D) were not known. 

Accelerated aging by a simple temperature variation not only increases the reaction rate but also modifies the spatial distribution of degradation events. Caution must be taken, therefore, in the interpretation of experimental results or in the comparison of data from various sources. 

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