Ultrathin films of poly(dimethylsi1oxane)-polyamide copolymers (PAS) with different silicone contents were prepared by the methods of water casting and spin coating. The surface properties of the films were investigated in detail using contact angle measurements and X-ray photoelectron spectroscopy (XPS). The water-cast films were thin enough to be applicable as laminate films for an artificial lung or an air-separator for oxygen-enrichted air. Uniform and ultrathin films were obtained by the spin coating method. XPS and contact angle measurements suggested that poly(dimethylsi1oxane) segments were condensed at the outermost surface of spin-coated PAS films. XPS measurements also revealed that the surface properties of PAS were affected by the molding method, especially the solvent evaporation conditions. ZUSAMMENFASSUNG Ultradiinne Filme aus Polydimethylsiloxan(PDMS)-Polyamid-Copolymeren (PAS) mit unterschiedlichen Silikonanteilen wurden durch FilmgieSen auf Wasser und Rotationsbeschichten hergestellt. Die Oberflacheneigenschaften der Filme wurden mittels Kontaktwinkelmessungen und Rontgenphotoelektronenspektroskopie (XPS) untersucht. Die auf Wasser gegossenen Filme waren diinn genug, um als Laminatfilme in kunstlichen Lungen oder als Trennmembranen zur Sauerstoffanreicherung von Luft

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In lightwave community antena television (CATV) systems as well as other optical fiber communication networks, a transmitted optical signal is known to be degraded by an intensity noise produced within the fiber due to the interference between the signal and doubly reflected light. We report on the improvements to the signal degradation due to the double Rayleigh backscattering by inserting optical isolators in the trunk lines of the systems. A carrier-to-noise ratio (CNR) has been calculated as a function of the number and the insertion 10ss of the isolators. The calculated results indicate that there is an optimum number of isolators, and if the insertion loss is less than 0.3 dB, the CNR degradation can be restored by more than 600/0. To test the calculated results, we conducted experiments for the specific case of employing one isolator, and obtained good agreements between the two.

SUMMARYThis paper describes the frequency-range widening of a three-transformer CATV divider consisting of one divider transformer and two matching transformers, all of which use a bead-type ferrite core. For frequency-range widening, the shape and material of the ferrite core, transformer windings, and transformer packaging are theoretically studied by means of a newly proposed high-frequency transformer equivalent circuit. For the divider designed based on the theoretical study, excellent measurement results are obtained in the frequency range of 20 to 3000 MHz, including a divider loss of 3.6 to 4.6 dB and more than 20 dB of coupling loss between terminals. In the design emphasizing a flat frequency characteristic at some expense of divider loss from a low to intermediate frequency range, the flatness is found to increase to about r0.3 dB. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(9): 4655, 2001