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  • 1
    ISSN: 1435-1536
    Schlagwort(e): Key words Electrorheological fluid ; Polyaniline ; Emulsion polymerization ; Dodecylbenzenesulfonic acid ; Suspension
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The electrorheological (ER) properties of dodecylbenzenesulfonic acid (DBSA) doped polyaniline suspensions in silicone oil were investigated. In contrast to chemically polymerized polyaniline in an acidic aqueous medium by oxidation polymerization, we adopted an emulsion polymerization technique in which aniline is polymerized in an emulsion of water and a nonpolar (or weakly polar) organic solvent. The effects of electric field strength and particle concentration on the ER properties of DBSA-doped polyaniline suspensions in silicone oil were then examined. Rheological measurements were also carried out using a rotational rheometer with a high-voltage generator in both controlled shear rate and shear stress modes, and the results showed that the ER properties were enhanced by increasing the particle concentration and electric field.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-1262
    Schlagwort(e): Keywords Peutz-Jeghers syndrome ; Hamartomatous polyps ; Intussusception ; Cancer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  Peutz-Jeghers syndrome is an autosomal dominant inherited disorder characterized by hamartomatous polyps in the small bowel and mucocutaneous pigmentation. Patients with Peutz-Jeghers syndrome often present as surgical emergencies with complications of the polyps, such as intussusception, bowel obstruction, and bleeding. Recently an increased risk of malignancies has also been reported. This study was initiated to determine the clinical features of Peutz-Jeghers syndrome in Korean patients, with special attention to the development of malignancies. Thirty patients with Peutz-Jeghers syndrome were investigated; their median age was 23.5 years, and symptoms appeared at a median age of 12.5 years. Family history was positive in one-half of cases, and mucocutaneous pigmentation was observed in almost all patients (93%). The jejunoileum was the most frequent site of the polyps, and there were generally 10–100 polyps. Multiple laparotomies were performed in a substantial portion of the patients, due mainly to polyp-induced bowel obstruction, and the surgical interventions were begun at a relatively young age (average 21.4 years). Four cases of small-bowel cancer and one case of breast cancer were detected in probands, at a relatively young age (mean 36 years). Cancers of the small bowel, stomach, colon, breast and cervix were diagnosed in the first relatives of the probands. Close follow-up from an early age should thus be performed in patients with Peutz-Jeghers syndrome as they are at high risk of surgical emergency and development of malignancy.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 277 (1999), S. 73-76 
    ISSN: 1435-1536
    Schlagwort(e): Key words Electrorheological fluid ; Polyaniline ; Dielectric spectrum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract As one of the intrinsically polarizable materials used in electrorheological (ER) fluid, polyaniline was synthesized by the chemical oxidation of aniline with ammonium peroxysulfate. ER fluids were prepared by dispersing polyaniline particles in silicone oil, and their rheological properties were measured. The effect of the polymerization temperature of polyaniline on its ER characteristics was investigated. ER fluids with polyaniline particles synthesized at −10°C (PA-10) showed the best ER performance (yield stress) compared with those synthesized at higher temperatures. A difference in the flow behavior of the ER fluids was also investigated through the dielectric spectra of ER fluids.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1435-1536
    Schlagwort(e): Key words Electrorheological fluid ; N-substituted copolyaniline ; Polyaniline ; Poly(aniline-co-o-ethoxyaniline)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Electrorheological (ER) characteristics of ER fluids, composed of suspensions of semiconducting polyaniline and two different copolyaniline particles in silicone oil, were determined experimentally. Ionic sodium diphenylamine sulfonate and nonionic o-ethoxyaniline were used to synthesize copolyanilines, i.e. N-substituted copolyaniline and poly(aniline-co-o-ethoxyaniline), respectively. ER fluids composed of these three different polymers were compared with respect to their rheological properties under an applied electric field. It was found that ER fluids containing a copolymer with an ionic group exhibited the highest ER performance among polyaniline and its copolymer systems in a shear-rate region above 1 s−1.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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