There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Minerals more readily adsorb amino acids with charged R groups than uncharged R groups, so that the incorporation of amino acids with charged R groups into peptides would be more frequent than for amino acids with uncharged R groups. However, 74% of the amino acids in the proteins of modern organisms contain uncharged R groups. Thus, what could have been the mechanisms that produced peptides/proteins with more amino acids with uncharged R groups than precursors with charged R groups? Should we expect the composition of amino acids adsorbed on minerals to be similar to those of present proteins? Was the adsorption of amino acids on minerals important for the origin of life? The lipid world offers an alternative view of origin of life. Liposomes contributed to elongation of peptides as well as select hydrophobic amino acids and peptides. These experiments could be showing the mechanism, which hydrophobic amino acids have been selected. However, liposomes have no influence on the stereoselectivity in the oligomerization of amino acids. In the present paper, several other mechanisms are also discussed that could produce peptides with a greater proportion of amino acids with uncharged R groups.

A review of adsorption of amino acids on minerals: was it important for origin of life?

Synthesis and characterization of goethite and goethite-hematite composite: experimental study and literature survey.

Characterization of the surface free energy of cellulose ether films

https://opus.lib.uts.edu.au/bitstream/10453/148539/2/Current-status%20and%20applications%20of%20polysaccharides%20in%20drug%20delivery%20systems.pdf

Current-status and applications of polysaccharides in drug delivery systems

The characterization of the electrical surface properties of Aquacoat, a polymer latex of great interest in pharmaceutical sciences, is described. The technique used is electrophoresis. Analysis was carried out of the effect of pH, electrolyte and surfactant concentration on the electrophoretic mobility of the latex particles. Increasing the pH of the dispersion medium provokes a monotonous increase in the value of the negative mobility. The electrolytes LiCl, KCl and NaCl give rise to larger mobilities when their concentration in solution is increased up to ca. 10−3 M, and a similar behavior is found in the presence of Na2SO4. The effect of raising the concentration of CaCl2 is to decrease the absolute value of the mobility as a consequence of double layer compression. Sodium dodecyl sulphate seems to adsorb on the particle surface increasing its negative charge, but when its concentration is close to 10−3 M saturation of the surface appears to take place, and an approximately constant mobility is suggested by data, whatever the pH of the medium. Finally, the mobility variations with LaCl3 concentration indicate adsorption of the La3+ cation when it is hydrolyzed (pH≥5), whereas non-hydrolyzed lanthanum has little effect on the particle charge.

Electric and adsorption properties of pharmaceutical polymers. Part I: Electrokinetics of Aquacoat

Electrokinetic studies of monodisperse hematite particles: effects of inorganic electrolytes and amino acids

An experimental investigation is described on the surface electric characteriza- tion of a commercially available latex, Aquateric, composed of cellulose acetate phthalate polymer particles, and used in enteric-controlled drug release. Since the surface charge of dispersed systems is an essential parameter governing most of their behavior, it is of fundamental importance to characterize how that quantity changes in the different envi- ronments in which the colloids could be used. The experimental method used in this work is electrophoresis; we report measurements of electrophoretic mobility of the latex as a function of pH and ionic concentration in the dispersion medium. It is shown that the zeta potential of the polymer particles is negative for the whole pH range studied and increases with pH as the dissociation of surface acetic acid groups proceeds. A plateau value is found for pHu 5, corresponding to complete dissociation of available ionizable sites. The values of the electrophoretic mobility (me) and the zeta potential (z) of Aquateric are also analyzed as a function of the concentration of 1-1 (NaCl) and 2-1 (CaCl2) concentration. The anoma- lous surface conductance (associated to the mobility of counterions adsorbed in the inner part of the electric double layer of the particles) manifests in a maximum in the EmeE- NaCl concentration plot for 10 03 M concentration. No such behavior is observed in the presence of CaCl2 solutions, where only a decrease of the mobility with ionic strength is observed. The effect of AlCl3 concentration on the mobility is also considered; it is found that at pH 2 aluminum ions adsorb on the particles and render them positively charged. When the pH of the suspensions is not maintained constant, the hydrolysis of aluminum gives rise to a less efficient control of the charge of the particles and no positive mobilities are observed. Electrophoretic mobility measurements as a function of pH at constant AlCl3 concentration show an abrupt change of me from negative to positive, interpreted as due to surface precipitation of Al(OH)3. When the pH is further increased, a second charge reversal is found, corresponding to the isoelectric point (pH of zero zeta potential) of Al(OH)3. q 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2721-2726, 1997

Electrokinetics and stability of a cellulose acetate phthalate latex

Study of in vitro release of corticoids in topical formulations

hematite shows a monotonous increase from E-1.5 to E-3.5 formed by a polymer or a phospholipid (8‐1 0 ); in those mms 01 /Vcm 01 ; in the case of elongated particles, the mobility investigations it was intended to take advantage of the magincreases with BMP concentration up to 10 04 M, larger concentra- netic properties of iron oxides ( 11 ) , since it has been demontions of the corticoid having little effect on the electrokinetic prop- strated that the release of drugs previously adsorbed on such erties of the particles. The effect of pH on the electrophoretic particles can be, to some extent, controlled by the application mobility of hematite is also investigated for two constant drug of external magnetic fields. concentrations (0.05 and 0.5 mM); the isoelectric point of the Furthermore, hematite particles can be synthesized as particles is shifted to a pH below 3, another indication of adsorp- monodisperse spheres of different sizes, or even as particles tion of the negatively charged phosphate groups of BMP. These of other geometries ( ellipsoids, cubes, spindles, etc.) by qualitative reasonings are confirmed by direct spectrophotometric rather simple and reproducible methods ( 12 ‐ 15 ) . Adsorpdeterminations of the amount of BMP adsorbed on both hematite tion of BMP on colloidal hematite of both spherical and samples: spherical and ellipsoidal. The effect of pH on the adsorption density, G, suggests that electrostatic interactions are not the ellipsoidal shape has thus been analyzed. The electrophoretic only forces responsible for adsorption. In fact, although G de- mobility of hematite suspensions was measured for different creases with pH for both types of particles, it remains measurable BMP concentrations in the dispersion medium, and the reup to pH 10, when strong electric repulsion is to be expected sults were compared to direct determinations of adsorption between hematite and phosphate groups. The effect of initial BMP of the drug on the particles. concentration on G is also studied. It is shown that a plateau region is reached in both samples, this indicating that their surfaces get EXPERIMENTAL saturated with BMP: the saturation begins when the coverage is of the order of E1/8 (spherical particles) and E1/40 (elongated particles) of a drug monolayer. Such difference might be due to Materials the ellipsoidal hematite particles having a lower positive surface charge, since they are synthesized in a different dispersion me- Betamethasone disodium phosphate ( BMP hereafter ) dium. q 1997 Academic Press

Adsorption of a Corticoid on Colloidal Hematite Particles of Different Geometries

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