Fractal images of quasicrystals as an example of Penrose lattice

The Penrose lattice, an example of quasicrystals, is considered as a fractal set. The generation of these sets in the graph tree form is considered. The problem of percolation of informodynamic characteristics and fractal dimensions defined in terms of the information entropy is solved for the constructed graphs.     

Olefin epoxidation with bis(trimethylsilyl) peroxide catalyzed by inorganic oxorhenium derivatives. Controlled release of hydrogen peroxide.

The replacement of organometallic rhenium species (e.g., CH(3)ReO(3)) by less expensive and more readily available inorganic rhenium oxides (e.g., Re(2)O(7), ReO(3)(OH), and ReO(3)) can be accomplished using bis(trimethylsilyl) peroxide (BTSP) as oxidant in place of aqueous H(2)O(2). Using a catalytic amount of a proton source, controlled release of hydrogen peroxide helps preserve sensitive peroxorhenium species and enables catalytic turnover to take place. Systematic investigation of the oxorhenium catalyst precursors, substrate scope, and effects of various additives on olefin epoxidation with BTSP are reported in this contribution.     

Electronic structure and photoelectron spectra of scandium and lutecium acetylacetonates and acetylacetoniminates

Scientific-Research Physicotechnical Institute, Far-East State University. M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 4, pp. 51–55, July–August, 1990.     

Synthesis of Highly Substituted Cyclobutane Fused‐Ring Systems from N‐Vinyl β‐Lactams through a One‐Pot Domino Process

In this contribution, aminocyclobutanes, as well as eight‐membered enamide rings, have been made from N‐vinyl β‐lactams. The eight‐membered products have been formed by a [3,3]‐sigmatropic rearrangement, whereas the aminocyclobutanes have been derived from a domino [3,3]‐rearrangement/6π‐electrocyclisation process. The aminocyclobutanes have been obtained in a highly diastereoselective fashion. The cyclobutane ring system tolerates fusion even if adjacent quaternary centres are present. Systems containing up to four fused rings are readily accessible. The reaction profile has been investigated by using Gaussian 03. This study suggests that two reaction pathways for aminocyclobutane formation are possible. In one pathway the [3,3]‐sigmatropic rearrangement is the rate‐limiting step and in the second pathway the electrocyclisation is rate limiting. Taken together, these reactions should facilitate the construction of fused heterocycles.     

Effect of montmorillonite on the structure and properties of powder epoxy compounds for polymeric coatings

Procedures for preparing nanomodified powder epoxy compounds with various concentrations of montmorillonite were examined. The dispersion of particles in the epoxy oligomers was studied by X-ray diffraction analysis and electron microscopy. The influence of the content of the modifiers on the physicomechanical properties of cured block specimens was analyzed.     

Viscoelasticity of a polymer matrix and fracture of heat-resistant fiber composites

This paper reports on the results of investigations into the general regularities of deformation and fracture of fiber composite materials based on new heat-resistant polymer binders. Fiber composites based on these binders can find wide application in various fields of engineering. It is established that an increase in the loss modulus of the polymer matrix decreases the probability of formation of a brittle crack in the matrix at the fiber break and increases the time interval between breakages of adjacent fibers. This leads to retardation of the correlated breakage of the fibers in fiber composite materials under loading, i.e., to an increase in their strength and fracture toughness. The inference is made that the matrix of high-strength heat-resistant fiber composites with a high fracture toughness should possess not only a high elasticity (this has long been known) but also good dissipative properties over the entire temperature range of operation.     

Effect of phase transitions of helium-3 in pores of wood carbonizate on the spin kinetics of 3He nuclei

The time of the nuclear magnetic relaxation of ³He gas in pores of Astronium carbonizate powder is studied as a function of gas pressure. Using the results of the measurements of the spin-echo amplitude, the dependences of the rates of spin-lattice and spin-spin relaxations on the number of helium atoms on the surface, in pores, and in the interparticle space of carbonizate powder have been determined. Analysis of the relaxation rates allows the identification of three possible basic phases of ³He in the system under consideration: solid film, gas phase, and liquid. Moreover, the character of spin kinetics in transitions between these phases has been determined.     

Computer analysis of the band contour of the photoelectron spectrum

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 53, No. 2, pp. 236–242, August, 1990.