In the present paper, the results of theoretical modeling of flux flow oscillator (FFO) included into phase-locked loop (PLL) system and its comparison with experiment are outlined. To describe theoretically the dynamics of phase-locked FFO, we have considered two models: first order PLL system and the PLL system with integral-proportional filter. While the first order PLL system may be treated analytically even in the frame of nonlinear PLL model and gives satisfactory agreement with experimental results, it does not describe all peculiarities of spectral density, which may be described well by a more sophisticated model with the integral-proportional filter. The quantitative prediction of spectral ratio improvement due to increase of PLL regulation bandwidth is given.

We present the novel results of studying tissue metabolites of the ear-nose-throat organs (pathological and relatively healthy mucosal tissues) during heating and thermal exposure using gas spectrometers of the terahertz (THz) frequency range based on non-stationary effects. Tissue metabolites of the ear-nose-throat organs obtained during surgery according to strict medical indications have been studied for the first time in the world. All the tissues used in the samples were histological verified for confirming the morphological diagnosis. For obtaining a unified picture, chemical compounds appearing during thermal decomposition of pathological and relatively healthy tissues were identified using the spectroscopic approach, with mandatory histological verification of the samples. The obtained results demonstrate that a powerful research tool has been proposed for evaluation of metabolites in otorhinolaryngology with detection of diseases markers.

Infrared Fourier spectra and spectra in the range of subterahertz frequencies (sub-THz) for the vapor phase over solid samples of high explosives (technical trinitrotoluene, nitroglycerine, and hexogen) were studied experimentally. The results from identifying products of the natural decay of high explosives by infrared Fourier and sub-THz spectroscopy are compared.