Abstract. The propagation of waves in weakly dissipative plasmas is investigated. A new expression for the wave energy flux is obtained, which is proportional to ∂λ mode /∂k, where λ mode is the real part of the eigenvalue of the dispersion tensor corresponding to the wave mode. Significant differences from the usual definition of dielectric wave energy flux occur in case of a non-negligible anti-Hermitian contribution to the dielectric tensor. This occurs, for example, near electron cyclotron resonance. The direction of the corrected wave energy flux is consistent with that of the trajectory of a wave beam crossing the EC resonance as obtained in Westerhof Plasma Phys. Control. Fusion 39 1015. It is shown that ray-tracing near cyclotron resonance can be performed with the use of λ mode as ray-Hamiltonian.

A power balance for waves in resonant dissipative media is formulated, which generalizes well-known expressions for dielectric wave energy density, wave energy flux, and dissipated power density. The identification of the different terms with wave energy density and flux remains only phenomenological. The result is better viewed as an equation for the evolution of wave intensity. In that form, its consequences are discussed in particular in relation to anomalous dispersion. A discrimination is made between boundary and initial value problems. For boundary value problems, anomalous dispersion is shown not to lead to unphysical results. In contrast, for initial value problems the solution for the evolution of wave intensity is shown to be at fault in the case of anomalous dispersion. Further illustration is provided by consideration of wave dispersion in a medium of charged harmonic oscillators and of ordinary-mode dispersion in plasma. Both are characterized by anomalous dispersion and show marked differences in the solutions of the dispersion relation solved either for complex wave vector at real frequency, k(ω) (applicable to boundary value problems), or for complex frequency at real wave vector ω(k) (applicable to initial value problems).

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For the first time the possibility of voltammetry used for the determination of aflatoxin B1 on a glassy carbon electrode was shown. The effect of pH of a supporting electrolyte on the analytical signal of aflatoxin B1 has been investigated and it was shown that there is a more pronounced peak with a maximum current at pH of 5.33. The most favorable supporting electrolyte for a linear range of detectable concentrations of aflatoxin B1 – 0.1 M (NH[4])[2]SO[4] was determined. The results of research on the development of conditions of voltammetric measurement of aflatoxin B1 are presented