Merging-zones approach

The merging zones approach was conceived independently by Bergamin-Filho et al. [1] and by Mindegaard [2] as the first strategy exploiting multiple injections in the context of flow injection analysis. As... 

J. Ruzicka, E.H. Hansen, Stopped-flow and merging zones. A new approach to enzymatic assay by flow injection analysis, Anal. Chim. Acta 106 (1979) 207. 

Merging-zone techniques are based on exploitation of the concentration gradients formed when two (or several) zones are injected simultaneously, and then allowed to merge—or penetrate into each other—thus yielding response curves, which either completely or partially overlap each other. The purpose of such an approach is twofold (1) to save sample and/or reagent solutions and (2) to create a composite zone that is information rich and that may yield a multiple readout. 

J. Rfi2i5ka and E. H. Hansen, Stopped-Flow and Merging Zones—A New Approach to Enzymatic Assay by Flow Injection Analysis. AnaL Chim. Acta, 106 (1979) 207. 

The flow system is designed to permit successive injections of the sample, each one accompanied by the injection of a different standard solution. Merging of the established zones permits the efficient implementation of the standard addition method involving a fixed sample dilution. The approach was initially exploited in the routine analysis of copper/ nickel alloys by ICP-OES [22], the spectral interferences being minimised by applying the generalised standard addition method [23]. This innovation however required the preparation of a large set of standard solutions. 

In the case of low interfacial coverage with surfactant, the collision of two emulsion drops (step A—in Fig. 2) usually terminates with their coalescence (step B—>C in Fig. 2). The merging of the two drops occurs when a small critical distance between their surfaces, hj. is reached. Sometimes, depending on the specific conditions (larger drop size, attractive surface forces, smaller surface tension, etc., — see, e.g.. Ref. 2), the approach of the two drops could be accompanied with a deformation in the zone of their contact (step B—>D in Fig. 2) in this way a liquidfilm of almost uniform thickness h is formed in the contact zone. This film could also have a critical thickness h, of rupture in fact, the film rupture is equivalent to drop coalescence (see step D—>C in Fig. 2). The mechanisms of coalescence... 

Fig. 19.42 The density of the water in Lake Bonney increases smoothly with increasing depth. A layer of dilute solution extends from the overlying ice to a depth of about 9.0 m. this layer merges into a transitional zone where the density increases from 1.0080 g/mL at 9.0 m to 1.1509 g/mL at 17.0 m. The density of the water at greater depth approaches a constant value at about 1.1750 g/mL. All densities were measure at 20°C. The density is expressed as the function (D - 1) x 100 such that if D = 1.0200, (D - 1) X 100 = 2.00 (Data from Jones (1969) using samples collected by Derry Koob)...

The discussion of the previous paragraph can also be illustrated following the approach of [55] in which the cohesive zone is viewed as providing an effective increase in the crack length. This can be seen from Fig. 11 because the results for the geometries with an initial crack and a cohesive zone all merge into the LEFM... 

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