Laser Raman scattering is conducted on aqueous solutions that contain organic chemicals that include glucose, lactate, ascorbate, pyruvate, and urea. At the concentrations of interest (below 1.0 wt. %), these various metabolites are found to scatter light independently of each other, and the scattering is linearly proportional to their concentrations. Through proper subtraction of water background scattering, the spectrum that is due to metabolite scattering is obtained and the composition of the solution can be determined by fitting its Raman spectrum with a linear sum of the known pure metabolite spectra. The spectrum of rabbit aqueous humor is presented and the potential application of this analytical method, such as noninvasive glucose monitoring, is discussed.

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In this paper we present measurements of the thermal diffusivities of five glasses between 100 and 500 K. These glasses have composition 0.15(Na20)0. 15(MO)0.05(Eu203)0.65(SiO~), where M is a divalent network modifier Mg, Ca, Sr, Ba, or Zn. The thermal transport is represented by a two-carrier model of conventional phonon-gas transport by extended phonons and thermally activated hopping of phonons whose eigenvectors are localized in the disordered network of the glass. The later contribution is required to explain the increase in the thermal diffusivity at temperatures above room temperature. The extended phonons produce a transport that is a decreasing function of temperature between 100 and 250 K in these glasses. Using the boson peak from Raman scattering as a measure of the phonon mobility edge, agreement with the temperature and frequency dependence of the two-localized-one-extendedphonon anharmonic process studied by Jagannathan et al. is obtained for both the localized and the extended phonons. The model is also applied to fused silica to account for results between 100 and 1100K, with the modification that the limiting process for the extended states does not explicitly depend on temperature.

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