Charge center

Monopole (T charge) unit negative charge centered on the n iiclen s. 

Fig. 4. Parameters in a coking cycle where (—) represents coke oven wall pressure ( ) coal charge center temperature (—) coke mass lateral contraction ...

The upper half of Figure 3.9 represents how a spherical explosive charge of diameter d produces a blast wave of side-on peak overpressure P and positive-phase duration r" " at a distance R from the charge center. Experimental observations show that an explosive charge of diameter Kd produces a blast wave of identical side-on peak overpressure p and positive-phase duration Kt at a distance KR from the charge center. (This situation is represented in the lower half of Figure 3.9.) Consequently,... 

R = Sachs-scaled distance from charge center (-)... 

The n values were high for all of the ionic liquids investigated (0.97-1.28) when compared to molecular solvents. The n values result from measuring the ability of the solvent to induce a dipole in a variety of solute species, and they will incorporate the Coulombic interactions from the ions as well as dipole-dipole and polarizability effects. This explains the consistently high values for all of the salts in the studies. The values for quaternary ammonium salts are lower than those for the monoalkylammonium salts. This probably arises from the ability of the charge center on the cation to approach the solute more closely for the monoalkylammonium salts. The values for the imidazolium salts are lower still, probably reflecting the delocalization of the charge in the cation. 

When the acid and basic pftjS of a zwitterion differ by only 3 or 4 units the compound may exist at isoelectric pH as an equilibrium between the true zwitterion and the formally neutral species. Oral absorption is much improved if this type of equilibrium exits. Charge proximate zwitterions are better absorbed than charge separated zwitterions. When the posihve and negative charge centers are close in space there is an overlap in the polarized aqueous salvahon shells so that the compound is less polarized than if the charges were far apart. 

Atoms are mostly empty space with small, dense, positively charged centers. 

A lone electron pair is under the direct influence of only one atomic nucleus, and its charge center therefore is located significantly closer to the nucleus than the centers of bonding electron pairs. Lone electron pairs are especially effective sterically in the following manner ... 

Since the hydration energy changes with p are driven by changes of Coulombic repulsion, a linear relationship between -A, and the reciprocal distance between the charged centers may be suspected, since the Coulombic energy is proportional to the reciprocal of the distance. The quantity, p + 2, may be assumed to be approximately proportional to the distance between the charged centers. We arrive... 

The order observed in the plots is easily rationalized. First one can consider the cases where two functional groups are present leading to two distinct charge centers. The doubly charged anions like SeO -, S20 (thiosulfate), and SO could then be... 

Consider a spherically symmetric molecule with superimposed centers of positive and negative charge, q. Apply an electric field (perhaps from a light wave), E(x). This will tend to separate the charge centers by an amount, x polarizing the molecule, and making it an electric dipole. The dipole moment will be qx = p which equals aE where a is the polarizability. 

Before a dislocation on one of the glide planes passes through the complex, the distance between the two charge centers is d = b = a0/>/2. After it has passed by the distance is d = V2(b) = a0. Therefore, if K is the static dielectric constant, and q = electron s charge, the energy difference between the before and after states is AU = (q2/Ka0)(V2-l). 

BF3 has substantial positive charge centered on the boron atom and negative charge located on the three fluorine atoms. 

Lipophilic ion exchangers traditionally used for polymeric membrane preparation are the anionic tetraphenylborate derivatives and the cationic tetraalkylammonium salts. The charges on both lipophilic ions are localized on a single (boron or nitrogen) atom, but the steric inaccessibility of the charged center, due to bulky substituents, may inhibit ion-pair formation in the membrane and provide, when necessary, non-specific interactions between ionic sites and sample ions. 

The use of deuterated organosilicon hydrides in conjunction with proton acids permits the synthesis of site-specific deuterium-labeled compounds.59 126 221 Under such conditions, the deuterium atom in the final product is located at the charge center of the ultimate carbocation intermediate (Eq. 62). With the proper choice of a deuterated acid and organosilicon hydride, it may be possible to use ionic hydrogenation in a versatile manner to give products with a single deuterium at either carbon of the original double bond, or with deuterium atoms at both carbon centers.127... 

Negative Charge Centers in High-Silica Frameworks. 201... 

Many zwitterionic organometallic compounds (betaines) are known in which positively and negatively charged centers of different nature are separated by various spacer groups. Substances of this type always exhibit the pronounced specific physical properties and high and unusual reactivity. Several types of organometallic betaines have been reviewed recently.1 4... 

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