Kinetics of Electron Transfer between Redox Cofactors in Photosystem I Measured by High-Frequency EPR Spectroscopy.

The kinetics of the primary electron donor P and the quinone acceptor A redox transitions were simultaneously studied for the first time in the time range of 200 μs-10 ms using high-frequency pulse Q-band EPR spectroscopy at cryogenic temperatures in various complexes of photosystem I (PSI) from the cyanobacterium PCC 6803. In the A-core PSI complexes that lack 4Fe4S clusters, the kinetics of the A and P signals disappearance at 100 K were similar and had a characteristic time of τ ≈ 500 μs, caused by charge recombination in the PA ion-radical pair in the branch of redox cofactors. The kinetics of the backward electron transfer from A to P in the branch of redox cofactors with τ < 100 μs could not be resolved due to time limitations of the method.

"Nutation" of electron spins in biradicals.

In this work, the nutation of the spins of unpaired electrons in the nitroxide biradical of bis‑methano[60]fullerene was experimentally studied. Nutation frequencies were found in a wide range of microwave field power. To interpret the obtained results, numerical calculations of the nutation of biradicals were carried out for a set of parameters of the spin-spin interaction of a pair of unpaired electrons and for different values of the Rabi frequency of the microwave field.

Experimental confirmation of the formation of collective modes of the magnetization motion of paramagnetic particles in dilute solutions due to spin exchange.

Experimental confirmation of the manifestations of new spin exchange paradigm in EPR spectra of N nitroxide radical solutions is presented. It was shown that in the region of relatively low concentrations of radicals, the two side components of the spectrum have a mixed shape (the sum of the absorptive line and dispersive line). The dispersion contributions in these two lines have opposite signs.

Experimental confirmation of the formation of a spin polariton in dilute solutions of paramagnetic particles.

Spin exchange during random bimolecular collisions of paramagnetic particles in dilute solutions leads to a surprising effect. Collective modes of motion of the average values of the transverse magnetization components (spin coherences) of subensembles of radicals with different resonant frequencies are formed. The elementary excitations of these modes can be considered as quasiparticles.

Efficient and Robust Search of Microbial Genomes via Phylogenetic Compression.

Comprehensive collections approaching millions of sequenced genomes have become central information sources in the life sciences. However, the rapid growth of these collections has made it effectively impossible to search these data using tools such as BLAST and its successors. Here, we present a technique called phylogenetic compression, which uses evolutionary history to guide compression and efficiently search large collections of microbial genomes using existing algorithms and data structures.