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  • 1
    ISSN: 1615-5947
    Keywords: Chylous ascites ; ascites ; abdominal aortic operations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Three patients, two women, one man (mean age 74 years), who had abdominal aortic aneurysms (2) or aortobifemoral surgery (1), developed chylous ascites postoperatively. They were studied to determine their clinical course and develop a plan for management of this complication. In each patient, the ascites was not manifest until abdominal swelling developed two weeks after operation, and the problem was confirmed by the finding of milky fluid on paracentesis. A low serum albumin (mean 2.6 gm) was also characteristic. The ascites was not altered by parenteral nutrition or reduction of dietary fat and ingestion of medium chain triglycerides. In one patient (man, age 93) the ascites resolved spontaneously two months after abdominal aortic aneurysm surgery. Another (woman, age 70) was cured following operative ligation of a lymphatic fistula identified at operation five weeks after abdominal aortic aneurysm repair. In the third (woman, age 60), the ascites resolved immediately following placement of a peritoneal venous shunt six weeks after an aortobifemoral bypass. Chylous ascites is rare after aortic surgery and manifests itself about two weeks after operation, at times after discharge from hospital. It has an indolent course, but may resolve spontaneously up to two months after operation. Its course appears not to be foreshortened by diet, including omission of fat, but can be successfully treated surgically with a shunt or fistula ligation. If done early a protracted hospital course may be avoided.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Titanates are versatile in the 1,4 polymerization of isoprene. The (R′O)4Ti/RAlCl2 catalyst gives either cis- or trans-1,4-polyisoprene, depending on the nature of both the titanate and the solvent. Primary titanates give cis-1,4-polyisoprene in both aliphatic and aromatic solvents. Secondary titanates give cis-polyisoprene in aliphatic solvents, and trans-1,4-polyisoprene in aromatic solvents. Tertiary titanates give trans-polyisoprene in both aliphatic and aromatic solvents. A mechanism is postulated which takes into consideration the role of the solvent. ESR studies of the various titanate-RAlCl2 catalysts were made; the paramagnetic structures are related to polymerization mechanisms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C-NMR has been used to examine a number of dichlorocarbene adducts of cis- and trans-polybutadiene prepared in a two-phase system. Dichlorocarbene was generated by reaction of aqueous or solid NaOH or KOH with CHCl3 in the presence of a phase transfer catalyst. Monomer compositions, comonomer sequence lengths, and stereochemical information were obtained for the resulting polymers. The polymers examined here were stereochemically pure and were treated as simple copolymers. Samples prepared using aqueous NaOH can be described as essentially random copolymers over the entire range of monomer composition. Samples prepared using solid alkali-metal hydroxides contain a higher fraction of blocked units than a polymer of comparable composition prepared using aqueous NaOH. This blockiness can coincide with the presence of two glass transition temperatures and a two-phase morphology as seen by transmission electron microscopy. Fractionation of a substantially blocked sample yielded a chlorine-poor fraction which was a random copolymer and a chlorine-rich fraction which was more blocked than the original unfractionated material.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics for the cycloaddition of dichlorocarbene to cis-1,4-polybutadiene (BR) have been examined for aqueous and solid sodium hydroxide-chloroform mixtures containing 350 molecular weight α-methyl-ω-hydroxy-poly(oxy-1,2-ethanediyl) (Carbowax 350) as a phase transfer catalyst. This study describes the influence of reaction variables on rate and the partitioning of dichlorocarbene between dichlorocyclopropanation and hydrolysis. The results are consistent with a kinetic model derived for the case where mass transfer is not rate limiting. However, this does not apply at high conversions where mass transfer control occurs due to large increases in viscosity. Higher BR concentrations can be achieved by replacing chloroform with methylene chloride containing stoichiometric amounts of chloroform. This mass action effect causes more favorable partitioning toward cyclopropanation; otherwise, chloroform and methylene chloride behave similarly as solvents. Water is an essential component in this reaction because it greatly increases the ability of the catalyst to extract sodium hydroxide into the organic phase.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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