Luminous flux absorptance

The extinction of the luminous flux passing through a foam layer occurs as a result of light scattering (in the processes of reflection, refraction, interference and diffraction from the foam elements) and light absorption by the solution. In a polyhedral foam there are three structural elements, clearly distinct by optical properties films, Plateau borders and vertexes. The optical properties of single foam films have been widely studied (see Section 2.1.3) but these of the foam as a disperse systems are poorly considered. 

In the above expression 70 is the intensity of luminous flux at a point where x = 0, and t is the turbidity. The quantity t is also referred to as the imaginary absorption coefficient. It is worth reminding here that x includes the... 

Absorptance (a) - Ratio of the radiant or luminous flux in a given spectral interval absorbed in a medium to that of the incident radiation. Also called absorption factor. [1]... 

Light absorbance (absorbance, absorptivity). The percentage of the total luminous flux incident upon a test specimen that is neither reflected from, nor transmitted through the specimen. Compare light reflectance and light transmittance. 

W, A,— wavelength m, c—speed of light in m/s. Measurements were carried out in the region of maximmn absorption of the pigments, separating from the spectrum of the lamp DKSSh-120 band width of 10 nm using interference filters at luminous flux in the plane of the electrode 10 mW/cm. ... 

An additional consideration when using in situ techniques is the volume of the luminal drug solution as water absorption and secretion during the perfusion may introduce errors in the lumenal concentrations and therefore in the calculated absorption. Various water flux correction methods have been published [42] including the co-perfusion of a non-absorbed marker such... 

Lu et al. (1992) performed a comparison of water and solute uptake in the in situ single-pass perfusion model and the isolated loops conscious rat model. Water flux in both experimental set-ups was found to be comparable. It was found that the solute (i.e. acetaminophen and phenytoin) membrane permeabilities (Pm) were consistently higher in the chronically isolated loops compared to the in situ perfusion. It was suggested that this was as a result of greater luminal fluid mixing in the in vivo system. A key advantage of the in vivo approach was that each animal can act as its own control for drug absorption studies. 

Permeability in the IPL has generally been measured by solute flux in the airway to perfusate direction. The flux of solutes in the perfusate to luminal fluid direction compared to absorptive flux [87] revealed a consistent disparity for a series of six hydrophilic compounds, which was suggested to be due to... 

OVERVIEW OF GI WATER AND ELECTROLYTE FLUX Huid content is the principal determinant of stool volume and consistency water normally accounts for 70-85% of total stool weight. Net stool fluid content reflects a balance between luminal input (ingestion and secretion of water and electrolytes) and output (absorption) along the length of the GI tract. The daily challenge... 

Fig. 8.4 a Absorption, excitation and emission spectra of (La, Ce, Tb)P04. Reprinted with permission from reference [20]. Copyright 2000 American Chemical Society, b Effects of fluxes on luminance of (La, Ce, Tb)P04 [19]... 

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