A summary is provided for terahertz attenuation signatures measured in spore-laden samples of Bacillus subtilis in three different forms: 1) concentrated powder; 2) dilute powder; and 3) aerosol. In addition to a surprising spectral narrowness, some signatures also display an increase in peak signature strength (per spore) with dilution of the sample. A model is constructed to explain this phenomenology based on the presence of optical phonons and electromagnetic interaction with the spore wall. Specifically, the spheroidal Bacillus spores admit surface modes that interact with radiation via polaritonic coupling and are underdamped if isolated from each other through a dilution or aerosol levitation. Hence, the results defy longstanding assumptions that the biomolecular-related terahertz vibrations are necessarily overdamped and have immeasurably weak attenuation.Index Terms-Bacillus subtilis, ellipsoidal particle scattering, peptidoglycan, polariton, resonant polarizability, spore coat, transverse optical phonon.

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A detailed study of the effects of ultraviolet radiation on type-I collagen has been conducted. We have confirmed that exposure to ultraviolet radiation lowers the denaturation temperature of type-I collagen and that the triple helical state is destroyed provided that the radiation dose exceeds a threshold level, which is defined as the incident radiation dose that raises the sample temperature above the (lower) denaturation temperature. For incident radiation doses below threshold, the collagen molecule remains in a triple helical state. Denaturation is determined by changes in the optical activity of the collagen solution. Furthermore, a new instrument has been developed and tested to measure the optical rotatory dispersion properties of chiral molecules. The advantage of this instrument is that it enables a real-time measurement of the optical activity of chiral macromolecules while exposing samples to ultraviolet radiation and requiring no special sample preparation techniques. Using a differential measurement scheme, system errors have been minimized.