ABSTRACT
We investigate the use of Terahertz (THz) Time Domain Spectroscopy (TDS) as a tool for the measurement of the index dispersion of multi-walled carbon nanotubes (MWCNT) in polypropylene (PP) based composites. Samples containing 0.5% by volume concentration of non-functionalized and functionalized carbon nanotubes are prepared by melt compounding technology. Results indicate that the THz response of the investigated nanocomposites is strongly dependent on the kind of nanotube functionalization, which in turn impacts on the level of dispersion inside the polymer matrix. We show that specific dielectric parameters such as the refractive index and the absorption coefficient measured by THz spectroscopy can be both correlated to the index of dispersion as estimated using conventional optical microscopy.
ABSTRACT
Pneumolysin was bound by human polymorphonuclear leukocytes in a reaction which occurred very rapidly at 0 degrees C. Low concentrations of pneumolysin were found to stimulate leukocyte migration and lysosomal enzyme secretion. At increasing lysin levels, inhibition of spontaneous migration and chemotaxis, cell death, and lysis were observed. Pneumolysin was also found to lyse platelets and to activate serum to become chemotactic.
Subject(s)
Blood Platelets/physiology , Neutrophils/physiology , Streptolysins/pharmacology , Bacterial Proteins , Cell Adhesion , Cell Aggregation , Cell Survival , Chemotaxis, Leukocyte , Humans , Muramidase/metabolism , Streptolysins/metabolismABSTRACT
Of 12 strains of Pseudomonas aeruginosa, 10 were found to produce heat-stable extracellular hemolysin in highly aerated peptone broth supplemented with glycerol, fructose, or mannitol. Glucose supported good hemolysin production only in medium that was highly buffered. The yield of both cells and hemolysin was lower with organic acids as supplement. Growth-limiting phosphate concentrations produced maximum hemolysin levels. Purified hemolysin preparations contained two hemolytic glycolipids. The kinetics of hemolysis at various levels of purified lysin and the effects of variation in lysin and erythrocyte concentration are described.
