Critical phenomena in 1D Ising model with arbitrary spin

The aim of this work was to study critical phenomena taking place in 1D Ising model with different exchange interactions signs and arbitrary spin values in a magnetic field. Exact analytical formulas for frustration fields, zero temperature magnetization and entropy at these fields are obtained. The general behavior of pair spin correlation function with the accounting of only interactions between nearest neighbors is examined. © 2018 The Authors, published by EDP Sciences.The reflorted study was carried out within the state assignment of FASO of Russia (theme «Quantum» n. 01201463332) and was funded by RFBR according to the research flroject n. 16-32-00032

Ordering and frustrations in generalized Ising chain

The Ising model on a one-dimensional monoatomic equidistant lattice with different nearest-neighbour and second-neighbour exchange interactions is researched. Generalized Kramers-Wannier transfer-matrix with translation on two periods of a lattice is introduced. A property similar to supercooling and superheating is detected. At the triple points phases are not individualized, but completely frustrated which corresponds to the phenomenon of critical opalescence. Exact analytical expressions for free energy, heat capacity and entropy including zero-temperature entropy are obtained. Various new special cases were analyzed and compared with all known results. All frustration fields for magnetization, frustration values for the zero-temperature entropy and magnetization are found. © Published under licence by IOP Publishing Ltd.Ural Branch, Russian Academy of Sciences, UB RAS: 18-2-2-11The research was carried out within the state assignment of Minobrnauki of Russia (theme ”Quantum” No. AAAA-A18-118020190095-4), supported in part by Ural Branch of the Russian Academy of Sciences (project No. 18-2-2-11)

AcrB Trimer Stability and Efflux Activity, Insight from Mutagenesis Studies

The multidrug transporter AcrB in Escherichia coli exists and functions as a homo-trimer. The assembly process of obligate membrane protein oligomers, including AcrB, remains poorly understood. In a previous study, we have shown that individual AcrB subunit is capable of folding independently, suggesting that trimerization of AcrB follows a three-stage pathway in which monomers first fold, and then assemble. Here we destabilized the AcrB trimer through mutating a single Pro (P223) in the protruding loop of AcrB, which drastically reduced the protein activity. We replaced P223 separately with five residues, including Ala, Val, Tyr, Asn, and Gly, and found that AcrBP223G was the least active. Detailed characterization of AcrBP223G revealed that the protein existed as a well-folded monomer after purification, but formed a trimer in vivo. The function of the mutant could be partly restored through strengthening the stability of the trimer using an inter-subunit disulfide bond. Our results also suggested that the protruding loop is well structured during AcrB assembly with P223 served as a “wedge” close to the tip to stabilize the AcrB trimer structure. When this wedge is disrupted, the stability of the trimer is reduced, accompanied by a decrease of drug efflux activity

THERMODYNAMIC AND MAGNETIC PROPERTIES OF ONE-DIMENSIONAL DECORATED CHAIN IN ISING MODEL

The Kramers-Wannier transfer matrix with translation to an arbitrary number periods of a linear chain is obtained. The exact analytical solution for largest eigenvalue of transfer matrix including magnetic field is derived.The research was carried out within the state assignment of Minobrnauki of Russia (theme ”Quantum” No. AAAA-A18-118020190095-4), supported in part by Ural Branch of the Russian Academy of Sciences (project No. 18-2-2-11)

Innovación en procesos y competitividad en empresas mexicanas desarrolladoras de software

Tesis (Maestría en Política y Gestión del Cambio Tecnológico), Instituto Politécnico Nacional, CIECAS, 2010, 1 archivo PDF, (124 páginas). tesis.ipn.m