Communicationsof 60:40. Instead of the expected decrease in line width beyond 1.2" with increasing reaction time a short decline and thereafter a new rise is observed experimentally which is likely, however, to be a consequence of specific reaction kinetics.In the range of the renewed increase of the FWHM the reflection profiles are slightly asymmetric; in the case of the 002 reflection the asymmetry occurs at lower diffraction angles. This can be understood in terms of the following model: reactions proceeding homogeneously from a starting phase A to a product phase B do not necessarily exhibit sharp Bragg lines for the intermediate phases A, -.B, but can display a finite "broadening" of the stoichiometry in a Adv Mater 4 (f992) No. 6 <> VCH Yerlagsgesellsthaft mhH, W-6940 Weinheim, fY92 0935-9648/92j0606-04lY $ 3 50f 25/(1
The morphology, thickness and surface pressure of the surfactant film of broncho-alveoalar lavage (BAL) fluid from patients with sarcoidosis were investigated during spontaneous adsorption of the BAL's surface active material at the air/aqueous buffer interface at 37 degrees C. The biochemical parameters of the BAL fluid determined were protein (Lowry), total phospholipids (from phosphate after ashing) and the individual phospholipids (HPLC). During the spontaneous adsorption of the pulmonary surfactant the surface pressure increased from initially 26 mN/m to 44 mN/m in the equilibrium state. Simultaneously to the increase of the surface pressure, a continuous increase of the reflectivity signal was observed by quantitative Brewster angle microscopy (BAM). The film thickness is calculated from the reflectivity values using an optical model. The effect of the uncertainty of the refractive index, which has to be estimated, is discussed. The BAM images show the inhomogeneous nature of the surfactant film with three distinct phases of different reflectivity, even at relatively low surface pressures. For the brightest phase, the thickness amounts to approximately 12 nm in the equilibrium state of adsorption. This suggests a multilamellar structure. Additionally, we found visual evidence for an adsorption mechanism involving the spreading of vesicles at the interface, in agreement with published results. Differences in the morphology and thickness of the pulmonary surfactant film reported in the literature are obviously due to the varying experimental conditions and materials. We think that the experimental conditions chosen in our study provide a more realistic view of the structure in the lungs in vivo.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.