Electronic paramagnetic resonance 504 INDEX

For our purpose, it is convenient to classify the measurements according to the format of the data produced. Sensors provide scalar valued quantities of the bulk fluid i. e. density p(t), refractive index n(t), viscosity dielectric constant e(t) and speed of sound Vj(t). Spectrometers provide vector valued quantities of the bulk fluid. Good examples include absorption spectra A t) associated with (1) far-, mid- and near-infrared FIR, MIR, NIR, (2) ultraviolet and visible UV-VIS, (3) nuclear magnetic resonance NMR, (4) electron paramagnetic resonance EPR, (5) vibrational circular dichroism VCD and (6) electronic circular dichroism ECD. Vector valued quantities are also obtained from fluorescence I t) and the Raman effect /(t). Some spectrometers produce matrix valued quantities M(t) of the bulk fluid. Here 2D-NMR spectra, 2D-EPR and 2D-flourescence spectra are noteworthy. A schematic representation of a very general experimental configuration is shown in Figure 4.1 where r is the recycle time for the system. 

Prom the electron paramagnetic resonance (EPR) spectmm of the nitroxide side chain, four primary parameters are obtained 1) solvent accessibility, 2) mobility of the R1 side chain, 3) a polarity index for its immediate environment, and 4) the distance between R1 and another paramagnetic center in the protein. Solvent accessibility of the side chain is determined from the collision frequency of the nitroxide with paramagnetic reagents in solution. The mobility, polarity, and distances are deduced from the EPR spectral line shape. For regular secondary stmc-tures, accessibility, mobility, and polarity are periodic functions of sequence position. The period and the phase of the function reveal the type of secondary stmcture and its orientation within the protein, respectively (71, 74). In the case of membrane proteins, the topography of the secondary stmcture with respect to the membrane surface can also be described (75, 76). 

There are various methods of the glass transition temperature evaluation based on temperature dependence of polymer physical properties in the interval of glass transition 1) specific volume of polymer at slow cooling (dilatometric method) 2) heat capacity (calorimetric method),3) refraction index (refractometric method) 4) mechanical properties 5) electrical properties (temperature dependence of electric conductivity) or maximum of dielectric loss 6) NMR ° 7) electronic paramagnetic resonance, etc. 

V0)P04 2H20 is a platy, bright yellow microcrystalline solid. When exposed to organic vapors in the air, it takes on a greenish tint as a result of surface reduction. The amount of present can be measured by EPR (electron paramagnetic resonance) spectroscopy and varies from 1 to 2%. It is most conveniently characterized by its X-ray powder diffraction pattern, which can be indexed on a tetragonal unit cell with a = 6.21 A and c = 7.41... 

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