An Artificial Heme Enzyme for Cyclopropanation Reactions

An artificial heme enzyme was created through self‐assembly from hemin and the lactococcal multidrug resistance regulator (LmrR). The crystal structure shows the heme bound inside the hydrophobic pore of the protein, where it appears inaccessible for substrates. However, good catalytic activity and moderate enantioselectivity was observed in an abiological cyclopropanation reaction. We propose that the dynamic nature of the structure of the LmrR protein is key to the observed activity. This was supported by molecular dynamics simulations, which showed transient formation of opened conformations that allow the binding of substrates and the formation of pre‐catalytic structures.     

Formation, physicochemical, and catalytic properties of the Mo-containing hydrotreatment catalysts on various supports. IV: The activity of the catalysts for the hydrotreatment of black oil

The activity and selectivity of the Mo-Ni catalysts prepared by the impregnation of supports (γ-Al₂O₃, hydrated titanium dioxide (HTD), and palygorskite-montmorrilonite clay (PMC)) are studied in the reactions of black oil hydrotreatment. The alumina support provides a higher catalytic activity in the hydrogenation of aromatics. The highest efficiency in desulfurization and demetalation of raw materials is achieved when hydrated titanium dioxide is used as a support. A low efficiency of the PMC-based catalyst is likely explained by the aggregation of the active component during hydrotreatment. The PMC support can be used as an additive to γ-Al₂O₃. Possible reasons for the dependence of the catalytic activity on the support are considered for various reactions.     

A recurrence method for a special class of continuous time linear programming problems

This article studies a numerical solution method for a special class of continuous time linear programming problems denoted by (SP). We will present an efficient method for finding numerical solutions of (SP). The presented method is a discrete approximation algorithm, however, the main work of computing a numerical solution in our method is only to solve finite linear programming problems by using recurrence relations. By our constructive manner, we provide a computational procedure which would yield an error bound introduced by the numerical approximation. We also demonstrate that the searched approximate solutions weakly converge to an optimal solution. Some numerical examples are given to illustrate the provided procedure.     

On the universally solvable embedding problem with cyclic kernel

It is proved that the universally solvable embedding problem with cyclic kernel is semidirect. Bibliography: 6 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 338, 2006, pp. 173–179.     

Effect of the complexation of ferric chloride with crown ethers on the rate and selectivity of the catalytic chlorination of chlorobenzene and toluene

Anionic and cationic complexes of ferric chloride with crown polyethers were synthesized. We studied the effect of complexes of various structure and nature on the rate and selectivity of the chlorination of aromatic compounds. In comparison with the catalytic action of ferric chloride, the para selectivity in the chlorination of toluene and chlorobenzene is enhanced, while the reaction rate is reduced in the presence of the complexes studied. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 2, pp. 111–114, March–April, 2008.     

The embedding problem with non-Abelian kernel for local fields

The embedding problem of local fields with p-groups is equivalent to its associated Abelian problem if the inequality d ≥ r + 2 is valid; here d and r are the numbers of generators of the Demushkin group and of the Galois group of an embedded field. Bibliography: 6 titles.     

Unsolvability in Radicals for a Class of Equations of Degree Five

A simple sufficient condition for the unsolvability in radicals of an irreducible equation of degree five given over ℤ in the Bring-Jerard form is found. Bibliography: 5 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 305, 2003, pp. 163–164.