A processing method was developed to coat polyglactin 910 (Vicryl) sutures with bioactive glass powder (45S5 Bioglass). High reproducibility and homogeneity of the coating in terms of microstructure and thickness along the suture length were achieved. Bioglass-coated sutures exhibited a high level of chemical reactivity in simulated body fluid (SBF), indicating their bioactive behavior. This was evident by the prompt formation of hydroxyapatite (HA) crystals on the surface after only 7 days of immersion in SBF. These crystals grew to form a thick HA layer (15 microm thickness) after 3 weeks in SBF. The tensile strength of the sutures was tested before and after immersion in SBF in order to assess the effect of the bioactive glass coating on suture degradation. The tensile strength of composite sutures was lower than that of as-received Vicryl sutures, 385 and 467 MPa, respectively. However, after 28 days of immersion in SBF the residual tensile strengths of coated and uncoated sutures were similar (83 and 88 MPa, respectively), indicating no negative effect of the HA layer formation on the suture strength. The effect of bioactive glass coating on the polymer degradation is discussed. The developed bioactive sutures represent interesting materials for applications in wound healing, fabrication of fibrous three-dimensional scaffolds for tissue engineering, and reinforcement elements for calcium-phosphate temporary implants.

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The forward scattering dispersion relations for the K-meson nucleon system are evaluated with a view to determining the coupling constants. Two different forms of dispersion relations as proposed by Igi are particularly convenient for this purpose. Using the most recent data on total cross sections and the zero-range scattering lengths in the evaluation of the unphysical continuum, reasonable values of the coupling constants are obtained.

The D13 pion-nucleon scattering phase-shifts are calculated using the Khuri representation suitably modified in order to exhibit explicitly the isolated nucleon pole in the u-channel. The results of the calculation are compared with the phase-shift analysis of ROrER. 1./ntroduetionSometime back KHURI 1 proposed a very interesting extension of the Regge representation which was subsequently employed to study mesonbaryon scattering at low energies 2. A modification of this Khuri representation was suggested by B6HM and RASmO a. The suggestion stems from the fact that in the case of a single Yukawa potential of range 1/IZ, there is an isolated pole at Zo = 1 + #a/2s in the z = cos ,9 plane and the cut in potential scattering theory really starts from 1 + 4 #Z/2s where s is the square of the c.m. energy. Therefore it is necessary to modify the Khuri representation so as to explicitly display these singularities in the z-plane.In pion-nucleon scattering at low energy, the phase-shift in the T= 89 J= 89 state is calculated in this way by first extracting out the t-channel rho-meson pole term and then by applying the Khuri representation to the resulting amplitude.

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