Surface charge positive

Differentiation, specialization, maturation, and transformation are generally accompanied by small changes in physical intrinsic properties of cells. Differences in size, density, and surface charge position each cell type in a rather unique part of a size—density—surface charge continuum. It is the purpose of cell separation to transport by some physical means dissimilar, closely neighboring cells from this imaginary space into separate fractions that are obtained after one-dimensional migration of the cells. 

The behavior of liposomes as an ocular drug delivery system has been observed to be, in part, because of their surface charge. Positively charged liposomes seem to be preferentially captured at the negatively charged corneal surface, compared with neutral or negatively charged liposomes. ... 

Fig. V-1. Variation of m / o and n /wo with distance for = 51.38 mV and 0.01 M uni-univalent electrolyte solution at 23°C. The areas under the full lines give an excess of 0.90 X 10 mol of anions in a column of solution of 1-cm cross section and a deficiency of 0.32 x 10 mol of cations. There is, correspondingly, a compensating positive surface charge of 1.22 x 10 " mol of electronic charge per cm. The dashed line indicates the effect of recognizing a finite ion size.

Molecular orbitals are useful tools for identifying reactive sites m a molecule For exam pie the positive charge m allyl cation is delocalized over the two terminal carbon atoms and both atoms can act as electron acceptors This is normally shown using two reso nance structures but a more compact way to see this is to look at the shape of the ion s LUMO (the LUMO is a molecule s electron acceptor orbital) Allyl cation s LUMO appears as four surfaces Two surfaces are positioned near each of the terminal carbon atoms and they identify allyl cation s electron acceptor sites... 

An additional method for increasing particle size deserves mention. When a precipitate s particles are electrically neutral, they tend to coagulate into larger particles. Surface adsorption of excess lattice ions, however, provides the precipitate s particles with a net positive or negative surface charge. Electrostatic repulsion between the particles prevents them from coagulating into larger particles. 

Surfa.ce (Charge. Inorganic particles have a surface charge in water that is a function of both the particle s character and the pH of the water. Each particle has an isoelectric pH value where the negative and positive charges on the surface just neutralize each other. Isoelectric points for some common inorganic particles are shown in Table 1. 

---