Correction to: Accelerating Reactive Transport Modeling: On-Demand Machine Learning Algorithm for Chemical Equilibrium Calculations

Transport in Porous Media - In the original publication of the article, Table 2 was published incorrectly.     

Triacetic acid lactone as a bioprivileged molecule in organic synthesis

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On a bifurcation governed by hysteresis nonlinearity

We consider autonomous systems with a nonlinear part depending on a parameter and study Hopf bifurcations at infinity. The nonlinear part consists of the nonlinear functional term and the Prandtl--Ishlinskii hysteresis term. The linear part of the system has a special form such that the close-loop system can be considered as a hysteresis perturbation of a quasilinear Hamiltonian system. The Hamiltonian system has a continuum of arbitrarily large cycles for each value of the parameter. We present sufficient conditions for the existence of bifurcation points for the non-Hamiltonian system with hysteresis. These bifurcation points are determined by simple characteristics of the hysteresis nonlinearity.     

Coupling for Markov renewal processes and the rate of convergence in ergodic theorems for processes with semi-Markov switchings

Coupling procedures for Markov renewal processes are described. Applications to ergodic theorems for processes with semi-Markov switchings are considered.This paper was partly prepared with the support of NFR Grant F-UP 10257-300.     

Phenol biosensor based on electrochemically controlled integration of tyrosinase in a redox polymer

An amperometric biosensor for the detection of phenolic compounds was developed based on the immobilization of tyrosinase within an Os-complex functionalized electrodeposition polymer. Integration of tyrosinase within the redox polymer assures efficient catechol recycling between the enzyme and the polymer bound redox sites. The non-manual immobilization procedure improves the reproducibility of fabrication process, greatly reduces the desorption of the enzyme from the immobilization layer, and, most importantly prevents fast inactivation of the enzyme by its substrate due to fast redox cycling. A two-layer sensor architecture was developed involving ascorbic acid oxidase entrapped within an electrodeposition polymer in a second layer on top of the redox polymer/tyrosinase layer. Using this sensor architecture it was possible to eliminate the current interference arising from direct ascorbate oxidation up to a concentration of 630 μM ascorbic acid. The effects of the polymer thickness, the enzyme/polymer ratio, and the applied potential were evaluated with respect to optimal sensor properties. The sensitivity of the optimized sensors for catechol was 6.1 nA μM⁻¹ with a detection limit of 10 nM, and for phenol 0.15 nA μM⁻¹ with a detection limit of 100 nM.     

An algorithm for the single-input partial pole assignment problem

An algorithm for translating unstable eigenvalues of single-input partial pole assignment problems based on rank-one transformations is suggested. Special attention is paid to the practical case where translations are constructed using inexact spectral information provided by the Arnoldi procedure. Estimates of the resulting perturbations of stable and translated poles are derived. These estimates depend on the accuracy of spectral information about the unstable poles. The algorithm proposed is illustrated with numerical examples. Bibliography: 11 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 229, 1995, pp. 5–28. Translated by A. Yu. Yeremin.     

Oxidation of 4-H-selenopyrans

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, p. 996, July, 1991.     

Role of the 3d orbitals of sulfur in the thiapyrylium cation

The electronic structure of the thiapyrylium cation with allowance for and neglect of the 3d orbitals of sulfur was investigated by the self-consistent field MO LCAO method within the CNDO/2 (complete neglect of differential overlap) approximation. Inclusion of the 3d AO of sulfur in the basis leads to slight redistribution of the electron density to favor equalization of the charges on the carbon atoms. A qualitative correlation of the calculated populations of the atoms with the chemical shifts of the PMR spectrum of the thiapyrylium cation was obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1627–1629, December, 1976.     

Thiapyrylium salts (review)

The literature data touching upon the synthesis of thiapyrylium salts and the stability of the thiapyrylium cation as compared with its isoelectronic analogs, as well as the nucleophilic, oxidation, anion-exchange, and other reactions of the salts with substituted and unsubstituted thiapyrylium cations are examined in this review.