Concentric interdigital

Figure 1.20 Periodic concentration profile of a regular multi-lamellar pattern in a rectangular interdigital micro mixer, determined by photometric-type analysis [119].

In turn, the interdigital micro mixer mixes much faster, provides more unique concentration profiles before reaction takes place and consequently changes the course of the reaction [125]. As a result, no high-molecular-weight polymer fraction is observed by GPC measurement and no fouling occurs, although the specific wall surfaces of the micro device are expected to promote deposition. 

In a more comprehensive study, 46 constituents were identified in the interdigital secretion of the white-tailed deer, 0. virginianus [129]. Only relatively volatile compounds up to methyl salicylate were identified in the secretion, because samples for GC-MS analysis were enriched from the headspace gas of the secretion collected on cotton swabs. Some variations in the relative concentrations of the compounds between the secretions from dominant and subordinate animals were observed, but it was not possible to conclude definitely whether these differences were related to age or dominance. 

Chemical work on the exocrine secretions of African antelope has concentrated on the interdigital secretions of members of the subfamily Alcelaphinae and the preorbital secretions of members of the subfamilies Antilopinae and Cephalo-phinae. 

The role of endogenous opioid peptides in mood and anxiety is relatively unknown. However, their existence in large concentrations within relevant limbic structures supports the hypothesis (M. S. Gold et al. 1982a). Direct opioid effects reportedly include anxiolysis and mood enhancement. The selective involvement of the opioids alone is unlikely because their activity is interdigitated with several conventional monoamines such as dopamine, serotonin, and norepinephrine. 

Anion detection at microelectrodes has not been studied widely. Amongst the first was the work of de Beer et al. [ 111 ] who manufactured a nitrite sensor with a tip just a few microns in diameter, which could detect nitrite ions down to 1 pM. This proved to be suitable for profiling the concentrations of nitrite anion within biofilms less than 1-mm thick inside water treatment plants. Other workers have found that use of an interdigitated microelectrode array [ 112] allows measurement of iodide via monitoring of its redox peak down to sub-micromole levels, making it a suitable technique for analysing mineral water. Carbon nanotubes coated onto Pt microdiscs have been utilised to make a nitrite sensor [113,114] with detection levels of 0.1 pM. Sulphide has also been detected at nickel microdiscs (50 pm diameter) [115]. 

Figure 1.93 Cross-sectional concentration profiles for multi-lamination flow patterns in the rectangular interdigital micro mixer for various flow rates [20] (by courtesy ofAIChE).

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