Hyaluronic acid plays an important role in regulating the transport of fluid and solutes in the interstitium. The concentration and molecular weight of hyaluronic acid in different connective tissues are different. These factors influence the hydraulic flow conductivity, K', of connective tissues. An experimental study of the effect of concentration and molecular weight of hyaluronic acid on the hydraulic flow conductivity is the subject of this work. Hyaluronic acid of different molecular weights were obtained by fractionating commercially available hyaluronic acid using ion-exchange column chromatography. The results were not reproducible, partly because of the elution process was not continuous. Nevertheless, three molecular weight fractions (6.99 to 11.1 X 10⁵ ) were obtained. Hyaluronic acid of lower molecular weights (0.454 to 1.65 X 10⁵) were obtained by acid hydrolysing some of the chromatographed fractions for 15 min., 1 hour and 2 hours. A more homogeneous hyaluronic acid fraction (M.W. = 1.96 X10⁵) was obtained by fractionating hyaluronic acid materials acid hydrolysed for 15 min. The hydraulic flow conductivity of solutions of hyaluronic acid can be calculated from the sedimentation coefficient of the solutions at 20°C, S₂₀‚ measured by ultracentrifugation. Centrifugation experiments determining the S₂₀ of the molecular weight fractions of hyaluronic acid at various concentrations were therefore undertaken. The results showed that S₂₀ decreased with increased concentration of hyaluronic acid. Also, the curves of as a function of hyaluronic acid concentration, c, converged at high concentration, indicating that a three dimensional molecular network is formed at high concentration and the extent of entanglement between molecules is the same for the high and low M.W. fractions. At lower concentrations, for the acid hydrolysed fractions, S₂₀ increased with M.W., which is in agreement with past sedimentation data. For the non-acid hydrolysed fractions, the difference in S₂₀ between two higher M.W. fractions is small, and the lowest M.W. fraction has consistently higher S₂₀ than the higher M.W. fractions. This finding does not agree with past literature results, and the difference in results is most probably due to experimental errors. However, when the fractionated non-acid hydrolysed fractions are taken as a high M.W. group (M.W. = 6.99 to 11.1X10⁵) and the acid hydrolysed fractions as a low M.W. group (M.W. = 0.454 to 1.96X10⁵), the curves of S₂₀ as a function of c of the low M.W. group fall below those of the high M.W. group, which is in agreement with past sedimentation data. The hydraulic conductivities (K'), calculated from S₂₀ data, for all the HA fractions varied inversely with concentration. The log-log plots of K' versus c compared well with the results of Ethier (1986). The K' versus c relationships for all the fractions converged at high concentrations. At low concentrations, the HA molecules of the high M.W. group has a higher K' than those of the low M.W. group. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

A series of chelating amino siloxide and alkoxide ligands have been prepared. Barium, lanthanide and zirconium complexes bearing these new ligands have been synthesized and characterized by NMR or X-ray crystallography. Reactivity of the zirconium complexes has been studied. The tris(siloxide) lanthanide(III) complexes are all monomeric in both solution and solid-state. A yttrium tris(siloxide) and a zwitterionic ytterbium tetrakis(siloxide) complexes have been characterized by X-ray crystallography. The yttrium complexes have shown high volatility. Mono(siloxide) barium(II) silamide complexes are dimeric as determined by X-ray crystallography, and barium bis(siloxide) exists as a monomer-dimer equilibrium in hydrocarbon solvents. Although highly soluble in hydrocarbon solvents, the barium complexes are non-volatile. A new aryl(siloxide) ligand has been synthesized and used as an ancillary ligand for the preparation of lanthanide dialkyl complexes. Although ligand redistribution was not observed, “ate”-complexes were isolated instead of neutral dialkyl complexes. Zirconium bis(aminodiolate) complexes were synthesized by reaction of tetrabenzyl zirconium and two equivalents of the ligands. The substituents on nitrogen were found to have a great effect on the structure. Mono(aminodiolate) zirconium dialkyl complexes were successfully synthesized by three different methods: protonolysis, ligand redistribution and metathesis. Thermal decomposition of these zirconium dialkyl complexes was found to show a marked dependence on the substituents at nitrogen. The α-methyl benzyl derivative decomposed by ortho-metallation of phenyl group exclusively and resulted in clean formation of a metallacyclic complex. The reaction of primary amines with the metallacycle allowed isolation of amide intermediates protonolysis of the benzyl group, and eventually resulted in formation of bridging imide complexes. The insertion reaction of carbonyl groups (C=O) into the metallacycle Zr-carbon bond proceeds regio- and stereoselectively. The first insertion products of carbonyl insertion were isolated, and the β-naphthaldehyde insertion product was characterized by X-ray crystallography. The metallacycle exhibited catalytic activity towards alkyne cyclotrimerization without preactivation. Zirconium cationic complexes were generated by alkyl abstraction using [special characters omitted]. The cationic complexes generated from the zirconium dibenzyl derivatives showed catalytic activity towards both ethylene and 1-hexene polymerization. A new cyclopentadienyl ligand bearing pendant fluorinated alkoxide functionality was synthesized. The zirconium complexes bearing this ligand exhibited remarkably high Lewis acidity, and the dichloride complex was shown to be catalytically active towards vinylether polymerization. / Graduate

The results of an investigation of the solubilities of silver chloride, silver bromide, silver iodide, and silver thiocyanate in water, in approximately 10, 20, 30, 40, and 50% by weight ethanol-water, methanol-water, acetone-water, and dioxane-water mixtures, and in an approximately 60% by weight dioxane-water mixture at 25°C are presented. The concentration of the anion of each of these four silver salts was varied between about 10^-5 and 10^-1 formal in each solvent. A radiotracer technique was used to determine the total silver content of these various solutions saturated with the appropriate slightly soluble silver salt. The results of "silver ion specific" electrode potential difference measurements in these saturated solutions were used in some of the calculations. Least-squares methods of data treatment were used to calculate the values of the thermodynamic equilibrium constants that describe the relationships among the various species in solution. A comparison of the results with the various theories of ionic interactions in solution is made and some of the inadequacies of these theories are discussed.

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