Diffusive scattering of energetic electrons by intense whistler-mode waves in an inhomogeneous plasma

This is the author accepted manuscript.Electron resonant interactions with electromagnetic whistler-mode waves play an important role in electron flux dynamics in various space plasma systems: planetary radiation belts, bow shocks, solar wind, and magnetic reconnection regions. Two key wave characteristics determining the regime of wave-particle interactions are the wave intensity and the wave coherency. The classical quasi-linear diffusion approach describes well the electron diffusion by incoherent and low-amplitude waves, whereas the nonlinear resonant models describe electron phase bunching and trapping by highly coherent intense waves. This study is devoted to the investigation of the regime of electron resonant interactions with incoherent but intense waves. Although this regime is characterized by electron diffusion, we show that diffusion rates scale linearly with the wave amplitude, 1. Introduction D ∝ Bw, in contrast to the quasi-linear diffusion scaling DQL ∝ B2 w. Using observed wave amplitude distributions, we demonstrate that the quasi-linear diffusion model significantly overestimates electron scattering by incoherent, but intense whistler-mode waves. We discuss obtained results in context of simulations of long-term electron flux dynamics in the space plasma systems.Natural Environment Research Council (NERC)Russian Science FoundationNAS

Detection of hepatitis C virus core protein in serum by atomic force microscopy combined with mass spectrometry

Yuri D Ivanov,1 Anna L Kaysheva,1,2 Pavel A Frantsuzov,1 Tatyana O Pleshakova,1 Nikolay V Krohin,1 Alexander A Izotov,1 Ivan D Shumov,1 Vasiliy F Uchaikin,1 Vladimir A Konev,1 Vadim S Ziborov,1 Alexander I Archakov11Institute of Biomedical Chemistry, 2PostgenTech Ltd, Moscow, RussiaAbstract: A method for detection and identification of core antigen of hepatitis C virus (HCVcoreAg)-containing particles in the serum was proposed, with due account taken of the interactions of proteotypic peptides with Na+, K+, and Cl- ions. The method is based on a combination of reversible biospecific atomic force microscopy (AFM)-fishing and mass spectrometry (MS). AFM-fishing enables concentration, detection, and counting of protein complexes captured on the AFM chip surface, with their subsequent MS identification. Biospecific AFM-fishing of HCVcoreAg-containing particles from serum samples was carried out using AFM chips with immobilized antibodies against HCVcoreAg (HCVcoreAgim). Formation of complexes between anti-HCVcoreAgim and HCVcoreAg-containing particles on the AFM chip surface during the fishing process was demonstrated. These complexes were registered and counted by AFM. Further MS analysis allowed reliable identification of HCVcoreAg within the complexes formed on the AFM chip surface. It was shown that MS data processing, with account taken of the interactions between HCVcoreAg peptides and Na+, K+ cations, and Cl- anions, allows an increase in the number of peptides identified.Keywords: hepatitis C virus, molecular detector, biospecific fishin

Atomic Force Microscopy Study of Protein–Protein Interactions in the Cytochrome CYP11A1 (P450scc)-Containing Steroid Hydroxylase System

Atomic force microscopy (AFM) and photon correlation spectroscopy (PCS) were used for monitoring of the procedure for cytochrome CYP11A1 monomerization in solution without phospholipids. It was shown that the incubation of 100 μM CYP11A1 with 12% Emulgen 913 in 50 mM KP, pH 7.4, for 10 min at T = 22°C leads to dissociation of hemoprotein aggregates to monomers with the monomerization degree of (82 ± 4)%. Following the monomerization procedure, CYP11A1 remained functionally active. AFM was employed to detect and visualize the isolated proteins as well as complexes formed between the components of the cytochrome CYP11A1-dependent steroid hydroxylase system. Both Ad and AdR were present in solution as monomers. The typical heights of the monomeric AdR, Ad and CYP11A1 images were measured by AFM and were found to correspond to the sizes 1.6 ± 0.2 nm, 1.0 ± 0.2 nm and 1.8 ± 0.2 nm, respectively. The binary Ad/AdR and AdR/CYP11A1mon complexes with the heights 2.2 ± 0.2 nm and 2.8 ± 0.2 nm, respectively, were registered by use of AFM. The Ad/CYP11A1mon complex formation reaction was kinetically characterized based on optical biosensor data. In addition, the ternary AdR/Ad/CYP11A1 complexes with a typical height of 4 ± 1 nm were AFM registered