An analytical expression is developed for describing the thermotropic behavior of membrane bilayers as studied by Raman spectroscopy. The expression is derived from a two-state model of the main gel to liquid crystalline phase transition in lipid bilayers. Experimental data for a variety of diacylphosphatidylcholines and their derivatives have been fit by least squares to the two-state expression to within currently achievable measurement error. Numerical techniques have been developed for placing bounds on the parameters of the two-state model in situations of sparse data in the phase transition region. By fitting the model to the measured spectroscopic data, estimates of the extent of cooperativity in the phase transition can be obtained in a systematic manner.
The available data on the microwave spectra of formaldehyde, forrnamide, and thioforrnaldehyde are critically reviewed for information applicable to radio astronomy. Molecular data such as rotational constants, centrifugal distortion parameters, dipole moments, hyperfine coupling constants, and structural parameters are tabulated. Observed rotational transitions are presented for the astronomically interesting isotopic forms of these molecules when available. Detailed centrifugal distortion calculations have been carried out for the most abufldant isotopic forms o(these molecules, namely, H 2 12C' 6 0, H 2 13C' 6 0, 14NH 2 12CH 16 0, and H212C32S. Transitions have been predicted and tabulated for the frequency ranges and I MHz to 300 GHz for H212C160. 100 MHz to 300 GHz for H 2 1:SC1 6 0, 500 MHz to 180 GHz for 14NH 2 12CH t6 0, 100 MHz to 300 GHz for H2120ZS. All predicted transitions include 95 percent confidence limits; measured transition error limits have been reproduced from the original literature. References are given for all data included.
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