Physical approach

Our method consists in the use of all magnetic particles testing techniques and to bear in mind the physical approach and the different processes combinations. 

As a consequence of this, i enever bulk dlffusional resistance domin ates Knudsen diffusional resistance, so that 1, it follows that fi 1 also, and hence viscous flow dominates Knudsen streaming. Thus when we physically approach the limit of bulk diffusion control, by increasing the pore sizes or the pressure, we must simultaneously approach the limit of viscous flow. This justifies a statement made in Chapter 5. 

Physics and chemistry researchers approach III—V synthesis and epitaxial growth, ie, growth in perfect registry with the atoms of an underlying crystal, differently. The physics approach, known as molecular beam epitaxy (MBE), is essentially the evaporation (14—16) of the elements, as illustrated in Figure 4. The chemistry approach, organometaUic chemical vapor deposition (OMCVD) (17) is exemplified by the typical chemical reaction ... 

An eminently practical, if less physical, approach to inherent flaw-dependent fracture was proposed by Weibull (1939) in which specific characteristics of the flaws were left unspecified. Fractures activate at flaws distributed randomly throughout the body according to a Poisson point process, and the statistical mean number of active flaws n in a unit volume was assumed to increase with tensile stress a through some empirical relations such as a two-parameter power law... 

McLean, J. W. Short, I. G. (1969). Composite anterior filling materials. A clinical and physical approach. British Dental Journal, 127, 9-18. 

This technique is readily adaptable for use with the generalized additive physical approach discussed in Section 3.3.3.2. It is applicable to systems that give apparent first-order rate constants. These include not only simple first-order irreversible reactions but also irreversible first-order reactions in parallel and reversible reactions that are first-order in both the forward and reverse directions. The technique provides an example of the advantages that can be obtained by careful planning of kinetics experiments instead of allowing the experimental design to be dictated entirely by laboratory convention and experimental convenience. 

The physical approach is not undisputable, as it does not take into account the conditions of the occurrences or of the production of the crude oil (e.g., onshore or offshore, water depths, climatic conditions, etc.). Therefore, some authors give a narrower definition of conventional oil. Campbell (2006), for instance, considers crude oil that is found under deep-water conditions (water depths greater 500 m) or in arctic regions, as well as NGL as unconventional oil. As a consequence, the remaining potential of conventional oil is estimated to be lower. 

The physical and economic or technical approaches made no big difference with respect to the oil that has been produced until now. According to the economic or technical approach - as advancing technology and rising prices will facilitate the economic production of new resources - the boundary will increasingly be shifted from unconventional oil towards conventional oil. This is, for instance, the case in Venezuela and Canada, where extra heavy oil and oil sands have already been economically produced for several years. According to the physical approach, however, this leads to a rise in the production volumes of unconventional oil. In this publication, the distinction between conventional and unconventional occurrences will be made according to the physical approach. 

Coulson described the first ten years of quantum chemists work on the electron valence bond (roughly 19281938) as work spent "escaping from the thought-forms of the physicist [my emphasis], so that the chemical notions of directional bonding and localization could be developed."45 Heisenberg earlier claimed that the Heitler-London treatment of the hydrogen molecule was not a characteristically physical approach, in contrast to Hund s more "general"... 

The physical approach uses alternating current (ac-) dielectrophoresis to separate metallic and semiconducting SWCNTs in a single step without the need for chemical modifications [101]. The difference in dielectric constant between the two types of SWCNTs results in an opposite movement along an electric field gradient between two electrodes. This leads to the deposition of metallic nanotubes on the microelectrode array, while semiconducting CNTs remain in the solution and are flushed out of the system. Drawbacks of this separation technique are the formation of mixed bundles of CNTs due to insufficient dispersion and difficulties in up-scaling the process [102]. 

The simple physical approaches proposed by Mallard and Le Chatelier [3] and Mikhelson [14] offer significant insight into the laminar flame speed and factors affecting it. Modem computational approaches now permit not only the calculation of the flame speed, but also a determination of the temperature profile and composition changes throughout the wave. These computational approaches are only as good as the thermochemical and kinetic rate values that form their database. Since these approaches include simultaneous chemical rate processes and species diffusion, they are referred to as comprehensive theories, which is the topic of Section C3. 

A physical approach was also applied to reduce the allergenicity of psyllium and psyllium-containing food products (Wullschleger, 1993). Psyllium was subjected to a thermal treatment imder certain pressure and moisture content for a predetermined time period to destroy the allergenic proteins. The preferred treatment conditions included a temperature of 245-265 °F, pressure range of 14—20 psi, and a time period between 55 and 75 min. This procedure may eliminate up to 100% of the allergenicity of psyllium. 

The use of CO as a chemical probe of the nature of the molecular interactions with the surface sites of metallic catalysts [6] was the first clear experimental example of the transposition to surface science and in particular to chemisorption of the concepts of coordination chemistry [1, 2, 5], In fact the Chatt-Duncanson model [7] of coordination of CO, olefins, etc. to transition metals appeared to be valid also for the interactions of such probes on metal surfaces. It could not fit with the physical approach to the surface states based on solid state band gap theory [8], which was popular at the end of 1950, but at least it was a simple model for the evidence of a localized process of chemical adsorption of molecules such as olefins, CO, H, olefins, dienes, aromatics, and so on to single metal atoms on the surfaces of metals or metal oxides [5]. 

The roots of the CALPHAD approach lie with van Laar (1908), who applied Gibbs energy concepts to phase equilibria at the turn of the century. However, he did not have the necessary numerical input to convert his algebraic expressions into phase diagrams that referred to real systems. This situation basically remained unchanged for the next 50 years, especially as an alternative more physical approach based on band-structure calculations appeared likely to rationalise many hitherto puzzling features of phase diagrams (Hume-Rotheiy et al. 1940). 

Equation (1.46) shows that a gap Ezb = 2 Vg opens dX.k = it fa induced by the weak periodic potential. Eollowing the same arguments given above, doubling a to 2a opens a gap at 7r/2a. We thus see that both the chemical and physical approaches lead to the same conclusions as expected. 

Ubbink, J., Kruger, J. (2006). Physical approaches for the delivery of active ingredients in foods. Trends in Food Science and Technology, 17, 244-254. 

Asbill C, El-Kattan A, Michniak B. Enhancement of transdermal drug delivery chemical and physical approaches. Crit Rev Ther Drug Carrier Syst 2000 17 621-658. 

Attention has been directed toward modifying functional properties of peanut proteins by chemical, enzymatic, and physical approaches. Chemical modification has included acetylation and succinylation treatments (28, 29). Marked improvement in emulsion capacity occurred as a result of this treatment if the proteins were extracted in acid 28). Beuchat et al. 

It should be obvious from the literature discussed in this article that progress in our understanding of the properties of flavin semiquinones and their role in flavoenzyme catalysis has increased dramatically over the past twenty years. This has been due to the application of sophisticated chemical and physical approaches, as well as to an increase in the number and diversity of flavoenzymes which have been purified to homogeneity in quantities sufficient for extensive study. 

This completes our summary of probabilistic and physical approaches to the theory of irreversible processes. As we have seen, probabilistic models are of great use in the description of irreversible processes but their ultimate justification rests on physical studies and approximations. 

Stochastic Processes, the Theory of, Probabilistic and Physical Approaches to (Oppenheim).15 1... 

Physical Approaches. Groundwater-exchange rates with lakes are traditionally estimated by careful measurements of hydraulic potentials within the groundwater system, followed by application of Darcy s law in the form of flow-net analysis or numerical modeling. However, these measurements can be time-consuming and costly, and can require monthly to weekly measurements at many piezometers to examine the three-dimensional nature of the hydraulic-potential field. In addition, characterization of the hydraulic conductivity of the aquifer is critical to physical approaches and typically leads to results with large uncertainties (I, 2). 

If the matter is more important than the recognition, it was also true, for Zeldovich in particular, that the manner was as significant as the matter. He always proceeded by a direct intuitive physical approach to problems. Even in areas where his ultimate accomplishment was a mathematical formulation adopted by others such as the Zeldovich number in combustion theory or the Zeldovich spectrum and the Zeldovich approximation to linear... 

The analysis indicates that presently quite adequate phenomenological models are available for description of the straining of commercial (polydisperse) polymers in the liquid state. A comparatively clear understanding of the mechanics of the processes of manufacturing of sleeve-type and flat films of molten thermoplastics also has been developed. So far, physical approaches have provided rheological models only for monodisperse polymers (the properties of which differ significantly from those of the ones used in industry). 

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