Irreversible indicators

On silicas alone, water bound to two surface hydroxyls appears rotationally less mobile than water bound to a single hydroxyl (16). On mica surfaces, the reorientation was found fast but irreversible, indicating angular trapping of this surface species (18). 

The electrochemical oxidation of tetrasilacyclopentanes 4 was found to be irreversible, indicating the instability of the generated radical cations. The oxidation potential versus saturated calomel electrode (SCE) was reported to be as follows for compound 4 (R = Pr ), 1.17V (CH3CN), 1.43V (CH2C12) and for compound 4 (R = < o-pentyl), 1.02V (GHjCN), 1.20 V (CH2C12) <2002EJI1772>. 

Figure 9. Fluorescent Irreversible Indicators that are Adaptable to the Microparticle Sensor Design.

Our approach of using controlled-release polymers to construct reservoirs of irreversible indicating chemistries allows sensors to be developed that operate continuously and for long periods. The approach has several advantages ... 

The addition of alkyl radicals onto C=N bonds such as imines, oximes, and hydra-zones has been studied extensively during the last 10 years. According to the kinetic data (Fig. 1) [2, 3], additions of alkyl radicals onto C=N bonds are much faster than additions onto C=C bonds, and the cyclization step is irreversible, indicating that C=N bonds are much better radical acceptors than C=C bonds. It is noteworthy... 

According to Pitsiavas et al. (1999), the inhibitory effect of amiodarone occurs at a lower iodide concentration than that for sodium iodide, and the effect of amiodarone is irreversible, indicating possible persistence of the Wolff—Chaikoff effect due to a persistently high intracellular iodide level. 

Adsorption is irreversible, indicating that a chemical interaction occurs between the hydrating C3A and SMF. Thus, the retardation of C3A may be explained by adsorption of SMF on the hydrating C3A surface. Similar... 

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