Anions, critical activities

Table E7J Critical Activity of Nitrate Anions for the Inhibition of Pitting in 18-8 Stainless Steel...

E7.6. A set of experimental data relating critical activity of hydroxide anions inhibiting pitting of 18-8 stainless steel in FeCls solutions and chloride activity are hsted in Table E7.3 [13]. 

E7.9. Pitting inhibitor effectiveness depends strongly on type and anion concentration. The thermodynamic (critical) activity, ai, required to inhibit pitting corrosion for a given activity of the aggressive anion is described by [13] ... 

E7.11. The critical activity of an inhibitor chloride ions is given by an expression of the form ... 

Choose any value of (CH) activity between 0.1 and 1.0 M. For example 1.0 M and estimate the value oflog(critical activities of the anions are listed in Table E7.9. 

Table E7.9 Critical Activities of Various Anions Anion Activity (M)...

Anionic Surfactants. PVP also interacts with anionic detergents, another class of large anions (108). This interaction has generated considerable interest because addition of PVP results in the formation of micelles at lower concentration than the critical micelle concentration (CMC) of the free surfactant the mechanism is described as a "necklace" of hemimicelles along the polymer chain, the hemimicelles being surrounded to some extent with PVP (109). The effective lowering of the CMC increases the surfactant s apparent activity at interfaces. PVP will increase foaming of anionic surfactants for this reason. 

P-Lactam antibiotics exert their antibacterial effects via acylation of a serine residue at the active site of the bacterial transpeptidases. Critical to this mechanism of action is a reactive P-lactam ring having a proximate anionic charge that is necessary for positioning the ring within the substrate binding cleft (24). 

In addition to their poor solubility in water, alkyl phosphate esters and dialkyl phosphate esters are further characterized by sensitivity to water hardness [37]. A review of the preparation, properties, and uses of surface-active anionic phosphate esters prepared by the reactions of alcohols or ethoxylates with tetra-phosphoric acid or P4O10 is given in Ref. 3. The surfactant properties of alkyl phosphates have been investigated [18,186-188]. The critical micelle concentration (CMC) of the monoalkyl ester salts is only moderate see Table 6 ... 

As mentioned in Section II.3, in the presence of film-destructive anions such as chloride ions, beyond the critical pitting potential Epiti pitting dissolution proceeds, creating semispherical pits (polishing-state pits), which are different in shape from the irregular pits that develop at the active region that is less noble than the activation potential Ea, where the corrosive reaction moves from the passive state to the active state (usually the activation potential Ea is different and less noble than the passivation potential Ep). 

R. J. Haynes, Active ion uptake and maintenance of cation-anion balance a critical examination of their role in regulating rhizosphere pH. Plant Soil 726 247 (1990). 

J. Bjerrum (1926) first developed the theory of ion association. He introduced the concept of a certain critical distance between the cation and the anion at which the electrostatic attractive force is balanced by the mean force corresponding to thermal motion. The energy of the ion is at a minimum at this distance. The method of calculation is analogous to that of Debye and Hiickel in the theory of activity coefficients (see Section 1.3.1). The probability Pt dr has to be found for the ith ion species to be present in a volume element in the shape of a spherical shell with thickness dr at a sufficiently small distance r from the central ion (index k). 

Aminophthalate anion Atmospheric pressure active nitrogen Analyte pulse perturbation-chemiluminescence spectroscopy Arthromyces rasomus peroxidase Ascorbic acid Adenosine triphosphate Avalanche photodiode 5-Bromo-4-chloro-3-indolyl 2,6-Di-t< r/-bu(yl-4-mclhyl phenol Bioluminescence Polyoxyethylene (23) dodecanol Bovine serum albumin Critical micelle concentration Calf alkaline phosphatase Continuous-addition-of-reagent Continuous-addition-of-reagent chemiluminescence spectroscopy Catecholamines Catechol... 

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