Amphoteric defined

Amphiphile-oil-water system, temperature of, 16 424-426 Amphiphiles, 16 420 Amphiphile strength, 6 424 Amphiphilic chemicals, 17 56 Amphiphilic copolymers, 20 482 behavior of, 20 483 well-defined, 20 485-490 Amphiphilic molecules, 15 99-101 Amphiphilic plasticizers, 14 480 Amphiphilic polymer blend, 23 720 Amphiphilic polymers statistical, 20 484-490 stimuli-responsive, 20 482-483 Ampholytes, 9 746-747 Amphoteric cyclocopolymers, water-soluble, 23 721 Amphoteric starches, 4 722 Amphoteric (zwitterionic) surfactants, 24 148... 

In very general terms, petroleum is a mixture of (1) hydrocarbon types, (2) nitrogen compounds, (3) oxygen compounds, (4) sulfur compounds, and (5) metallic constituents. Petrolenm prodncts are less well defined in terms of heteroatom compounds and are better defined in terms of the hydrocarbon types present. However, this general definition is not adequate to describe the true composition as it relates to the behavior of the petroleum, and its products, in the environment. For example, the occnrrence of amphoteric species (i.e., compounds having a mixed acid-base natnre) is not always addressed, nor is the phenomenon of molecnlar size or the occnrrence of specific functional types that can play a major role in petrolenm behavior. 

The oxides are the compounds of any element with oxygen the oxides of non-metals are defined as acidic oxides, while the oxides of metals are denoted as basic oxides. Some oxides have both acidic and basic characters and are consequently defined as amphoteric [4,77]. 

Since peptides are amphoteric, Zt and Zc are expected to show nonlinear dependencies on pH. Similar behavior has been observed for various synthetic peptides separated on both strong anion and strong cation HP-IEX sorbents. As a consequence, the minima in the In /t iex i versus pH plots at a defined concentration of displacing salt will not usually occur at the predicted p/ value of the peptide, but rather at another pH value. Implementation of an optimized HP-IEX separation of peptides thus requires that the sequence microlocality and extent of ionization of the surface-accessible amino acid side chains, or the N- and C-terminal amino and carboxy groups, respectively, are taken into account. 

J. Kendall, J. E. Booze, and J. C. Andrews 3 have shown that the formation of hydrates, in the sense of water of crystallization, with the weak acids very seldom occurs, and when hydrates are formed, the acid has the amphoteric character of a phenol. There is also a regular increase in the tendency of an acid to form hydrates, as the strength of the acid increases, until, with the strong acids, well-defined stable hydrates appear. The complexity and stability of the hydrates increase with the strength of the acid. These facts are in harmony with the weak acid nature of water. 

The main characteristics of amphoteric surfactants is their dependence on the pH of the solution in which they are dissolved. In acid solutions, the molecule acquires a positive charge and it behaves like a cationic, whereas in alkaline solutions they become negatively charged and behave like an anionic. A specific pH can be defined at which both ionic groups show equal ionization (the isoelectric point of the molecule). 

Arrange a table of the dioxides of the elements of Group IV column 1, the formulas of the dioxides, placing those of the A family at the left and those of the B family at the right of the column column 2, the character of the dioxide specifying, a. = distinctly acidic, w. a. = weakly acidic ind. = indifferent w.b.= weakly basic b. = distinctly basic amph. = amphoteric column 3, the formula of as well defined a salt as possible of the dioxide column 4, the extent of hydrolysis of this salt, specifying much, little, or none. 

Despite the poorly defined nature of the shear plane, EM has been commonly used as a noninvasive technique for evaluating various surface-surface and surface-solute reactions, such as evaluating the PZC for amphoteric minerals specific sorption reactions for inorganics and organic compounds on mineral surfaces ... 

The N-hydroxy structure (26) was preferred123 to an iV-oxide representation on account of the amphoteric nature of the product and because the derived acetate formed a well-defined hydrochloride salt. Hydrogenation of these N-hydroxyimidazoles over Raney nickel gives imidazoles in 60-94% yields.122 The reaction has been adapted for the preparation of 4-mercaptoimidazoles, using an a-ketothionamide (27) with an aldimine.124... 

From examination of the dewetting process, the requirement for the wettable (by water) or hydrophilic surface could be defined that the contact angle of water should be below ti/2. By the same principle, a contact angle above n could be set as the requirement for the nonwettable or hydrophobic surface. The surface whose contact angle is between n and ti/2 could be viewed as the surface having amphoteric wettability or amphoteric hydrophilicity/hydrophobicity. 

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