It is well known that the recursion method (RM) /1/ allows t o calculate bulk and surface properties of the electron subsystem without construction of the full band picture and a l s o the density of s t a t e s (D06) for disordered systems /2/ because it is not based on symmetry properties under i t s construction. A distinctive feature of the RM is a good description of the short-rarge o r d e r (SRO) by recursion construction of an orthonormal basis in real space which transforms the Hamiltonian t o the chain model /3/. In practice the main uncertainty in the RM consists in suggestions about the behavior of the recursion coefficients an, b f o r n+m, which determine the local Green function as an infinite continued fraction (CF) because only a finite number of recursion levels n < no is calculated (no also depends on the size of a cluster of atoms that can be treated), and the C F is terminated by the function t n (z), z = E + id, having analytical properties of Green functions: n 0 1 C(z, t n (4) = o ( z -a o -b T 2 (za l -b2 ( 2 -... b2 n -1 0 * (1) ( z -a n -1b : tn ( 2 ) ) 0 0 0 V e r y often one uses the terminating function with constant coefficients (an = an , b = b proach t o construct the DC6 with a finite number of coefficients an' bn was proposed in /4/, it uses the Gaussian quadrature. Both approaches to the RM 0 f o r n > n and the DC6 is in the band with width 4bn ). Another ap-0 n n 0 0 1) SU-142092 Troitsk, Moscow region, USSR.

DNA aptamers are oligonucleotides specifically bound to target molecules that can serve as antibodies of nucleic acid nature. For diagnosing the infection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), methods using antibodies specific to antigens on the virus are broadly used. We generated by classical SELEX a number of aptamers, interacting with the receptor-binding domain of SARS-CoV2 spike protein (SARS-CoV2 Spike RBD) from Wuhan-Hu-1 strain. The sequence identification was performed using a novel methodology based on the nanopore sequencing. For sequence identification of selected aptamers, we created the novel protocol for aptamer identification based on nanopore sequencing. We identified the best aptamer candidate named MEZ. It was chemically synthesized and tested for binding with SARS CoV2 Spike RBD domain of the S-protein from different strains. Kd of the complex is 6.5 nM being comparable with known aptamers. Virus neutralization tests demonstrate similar results for already known and MEZ aptamers. We identified differences for aptamers binding to SARS-CoV-2 Spike RBD from Wuhan-Hu-1 and Omicron strains. MD simulations reveal that the number of hydrogen bonds between the protein and aptamer is higher for the more stable complex. Moreover, dynamic network analysis show that the motions of the aptamer and protein are correlated to a higher extent in a more stable complex. Based on the experimental data and computational results we can conclude that the authentic RBD-aptamer complex has two specific points for interaction and the 3'-end of aptamer is responsible for strain identification. Therefore, the selected aptamer based on experimental data can be an alternative biological element for the development of SARS-CoV-2 diagnostic testing with strain specificity and cost efficiency due to the short length of aptamer being 31 nucleotides.

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The results of DOS calculations for the s-d valence band of disordered paramagnetic Cu0.50 Ni0.50 alloy by the recursion method are presentef for total and partial densities of states. Use of the CPA for the continued fraction termination has allowed to reveal the fine structure of the DOS in the band, which is due to non mean field features of the recursion method, also to reduce required computer time. Results for different sets of LCAO parameters, comparison of the DOS calculations with the experiment and other calculations results are presented.