Functional biochemical properties of 5 batches of the fibrinogen component of a fibrin glue produced by the ZLB Central Laboratory, Bern, each consisting of 4 different in-process samples (taken after the first and second precipitation step, lyophilization, and dry-heat treatment) were studied in vitro. We focused our attention on the effect of the anti-viral treatment of the lyophilized product by dry heat for 1 h at 100 degrees C. A slight reduction in maximal turbidity of all heat-treated samples was observed during the clotting assay compared to nontreated samples. Treatment with dry heat did not result in generation of fibrinogen fragments that might accelerate tissue-plasminogen-activator (t-PA)-enhanced plasminogen to plasmin conversion. The time course of fibrin cross-linking by factor XIII showed no differences between heated and unheated samples. This result indicates that exposure of the fibrinogen component to severe heat neither reduced activity of factor XIIIa nor affected the correct alignment of cross-linking sites in polymerized fibrin. Incubation of fibrinogen with thrombin, plasminogen, and t-PA resulted in a slightly enhanced degradation of fibrin derived from the heat-treated samples. The amount of residual moisture, determined to be within the range of 0.6-2.1% before heat treatment, did not influence clotting, cross-linking, and fibrinolysis parameters. In conclusion, the virus inactivation treatment by dry heat for 1 h at 100 degrees C induces no significant alterations of the in vitro biochemical properties of the fibrinogen component of this fibrin glue.
Whisker and fiber reinforced ceramic composites offer the potential for increased fracture toughness and fracture strength. However, differences in thermal expansion between whisker and matrix generate residual stresses which may affect the mechanical properties of such composites. The microscopic stress can be determined by analyzing the strain contrast around SiC whiskers quantitatively, similar to the strain analysis performed on ZrO2 inclusions in AI2O3. Previously obtained experimental TEM results on strain contrast around SiC whiskers embedded in Al2O3 were only qualitatively. In the present study the experimental observations are quantitatively evaluated.Contrast simulation requires the knowledge of the matrix displacement field in the vicinity of the whisker. Due to two force-free surfaces adjacent to the inclusion, Eshelby’s method for an inclusion in an infinite matrix can not be used for the evaluation of the elastic field in a TEM foil. Therefore, the Green’s function method was applied to fulfill the elastic boundary conditions for both surfaces neglecting only the elastic interaction between the surfaces.
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