Embolyx E, an occlusive and nonadhesive embolic agent, is capable of producing permanent occlusion of swine RMB with the development of mild intra- and perivascular inflammatory changes and no clinical complications. The slow endovascular delivery of DMSO produces no untoward angiographic, pathological, or clinical changes. A fast injection of DMSO causes endothelial necrosis and severe inflammatory response in the arterial wall. This embolic material seems to have appropriate biochemical, anatomic, and histopathological characteristics to be used in the treatment of cerebral arteriovenous malformations or vascular cranial base tumors.

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SynopsisResoles, thc complex, heat-sensitive product mixture from the alkali-catalyzed reactions of phenol with formaldehyde were investigated by gel-permeation chromatography (GPC). The low molecular weight species of these resins which consisted of monoand dinuclear methylol phenols were resolved into multiple peaks. Model compounds were used to identify the peaks of the specific methylol phenols or methylene etherbridged diphenols. Differences in the refractive index of individual species restricted the quantitative analysis of low molecular weight components in the resole. The effects of sodium and barium hydroxides and hexamethylene-tetramine as catalysts, reaction temperature, and time on the total composition of a resole are demonstrated with the gel-permeation chromatographic spectrum and with the aid of NMB. Formation of a "secondary" resole by methylolation of the bisphenol of formaldehyde was also monitored by GPC. 2193

The selective uptake of potassium ions versus tetramethylethyl-, ethyl-,and propylammonium ions by fully neutralized, crosslinked polymethacrylate gels was measured in aqueous, mixed aqueous, and nonaqueous solvents. Swelling pressures in water were calculated from isopiestic data, so the Coulombic contribution to the total free energy of the exchange process could be calculated and compared with theory. A good fit between experiment and theory was possible only by assigning values for the dielectric constant of water in these gels of about 30 in the K-TMA state and 15 in the K-TEA state.5742

The reaction of 4,4'-dichlorodiphenylsulfone with the caprolactamate anion was investigated. The expected diamide derivative could not be isolated. Instead, high molecular weight polymer was obtained in the presence of excess &-caprolactam. I11 defined species resulted when the reaction was conducted in aprotic solvents.The initiation of the base-catalyzed polymerization of e-caprolactam with 4,4'dichlorodiphenylsulfone and other activated aromatic halides was then studied. The rate of polymerization is relatively slow compared to other known initiators. This is an advantage in casting operations where a finite pot life may be required. The results are rationalized in a proposed mechanism wherein the formation of the initiator is the rate determining factor.The anionically prepared Nylon 6 was characterized via several techniques such as gel permeation chromatography, light scattering and melt rheology. Mechanical properties were also determined. ZUSAMMENFASSUNG :Die Reaktion von 4,4'-Dichlordiphenylsulfon mit dem Caprolactamat-Anion wurde untersucht. Das erwartete Diamid-Derivat konnte nicht isoliert werden. Statt dessen wurde in Gegenwart von uberschiissigem e-Caprolactam ein Polymeres von hohem Molekulargewicht erhalten. Die Durchfiihrung der Reaktion in aprotischen Losungsmitteln gab ein schwierig zu definierendes Molekulgemisch. 4,4'-Dichlordiphenylsulfon und andere aktivierte aromatische Halogenide wurden als Starter fiir die Alkali-katalysierte Polymerisation von c-Caprolactam studiert. Die Bildung von Polymeren ist im Vergleich zu anderen bekannten Initiatoren verhiiltnismiiDig langsam. Das ist ein Vorteil in GieDverfehren, wo ein bestimmtes ,,Pot-Life" gefordert wird. Die Ergebnisse werden in einem vorgeschlagenen Reaktionsmechanismus, worin die Bildung des Starters der umsatzbestimmende Faktor ist, verstiindlich.Das anionisch hergestellte Nylon 6 wurde mit verschiedenen Techniken wie Gel-Permeations-Chromatographie, Lichtstreuung und SchmelzfluBverhalten charakterisiert. Die mechanischen Eigenschaften des Polymeren wurden ebenfalls bestimmt.