Turbid media

Fluorescence-lifetime-based tomography for turbid media. Opt. Lett. 30, 3347-9. 

S. J. Madsen, B. C. Wilson, M. S. Patterson, Y. D. Park, S. L. Jacques, and Y. Hefetz. Experimental tests of a simple diffusion model for the estimation of scattering and absorption coefficients of turbid media from time-resolved diffuse reflectance measurements. Applied Optics, 31 3509-3517, 1992. 

Besides the fluorescence coefficient, the optical absorption and scattering coefficients of the sample are the most important parameters in quantative fluorescence spectroscopy of turbid media. In principle two or, if the anisotropy parameter has to be determined, three independent measurements are sufficient to separate the coefficients that appear in all equations as sums or proportions. However, for better accuracy, one of the geometrical parameters (sample thickness, angle of incidence, distance from the irradiated spot) as well as the wavelength of irradiation should be varied over a wide range, and then the data should be fitted with the help of the corresponding model equation. 

G. Mie, Contributions to the optics of turbid media, especially colloidal suspensions of... 

P. Matousek, Inverse spatially offset Raman spechoscopy for deep noninvasive probing of turbid media, Appl. Spectrosc., 60, 1341-1347 (2006). 

Debarre, D., Olivier, N. and Beaurepaire, E. 2007. Signal epidetection in third-harmonic generation microscopy of turbid media. Opt. Express 15 8913-24. 

Miscellaneous. A manometric technique utilizing a Warburg apparatus has been used to follow esterase activity. The carbon dioxide liberated from sodium bicarbonate by the fatty acids is measured (Willart and Sjostrom 1959). An agar diffusion procedure has been utilized for screening microorganisms for lipolyptic enzymes. The presence of lipase is indicated by clear zones in the turbid media (Lawrence et aL 1967). 

Present data illustrate the technique for an in situ determination of surface areas. Related methods had been applied primarily to the study of site distributions in clay minerals, particularly by Russian workers (66), and they were used by Bergmann and O Konski in a detailed investigation of the methylene blue-montmorillonite system (3). In fact, changes in electronic spectra arising from surface interactions received sufficient attention in the past to warrant their review by A. Terenin (65). Most of these investigations involved transmittance spectra but new techniques in reflection spectrophotometry and applications of the Kubelka-Munk relation have facilitated the quantitative evaluation of spectra in highly turbid media (35, 69, 77). Thus, in agreement with the work of Kortiim on powders and anhydrous dispersions (31, 32, 33), our results demonstrate the applicability of the Kubelka-Munk function... 

Fig. 3.1. Three main light components within turbid media...

However, electrochemically based transduction devices are more robust, easy to use, portable, and inexpensive analytical systems [45]. Furthermore, electrochemical biosensors can operate in turbid media and offer comparable instrumental sensitivity. Many electrochemical sensing and biosensing devices were reported [46-48]. 

---