Mono- and Diamination of 4,6-Dichloropyrimidine, 2,6-Dichloropyrazine and 1,3-Dichloroisoquinoline with Adamantane-Containing Amines

N-heteroaryl substituted adamantane-containing amines are of substantial interest for their perspective antiviral and psychotherapeutic activities. Chlorine atom at alpha-position of N-heterocycles has been substituted by the amino group using convenient nucleophilic substitution reactions with a series of adamantylalkylamines. The prototropic equilibrium in these compounds was studied using NMR spectroscopy. The introduction of the second amino substituent in 4-amino-6-chloropyrimidine, 2-amino-chloropyrazine, and 1-amino-3-chloroisoquinoline was achieved using Pd(0) catalysis.     

Log-gases on quadratic lattices via discrete loop equations and q-boxed plane partitions

We study a general class of log-gas ensembles on (shifted) quadratic lattices. We prove that the corresponding empirical measures satisfy a law of large numbers and that their global fluctuations are Gaussian with a universal covariance. We apply our general results to analyze the asymptotic behavior of a q-boxed plane partition model introduced by Borodin, Gorin and Rains. In particular, we show that the global fluctuations of the height function on a fixed slice are described by a one-dimensional section of a pullback of the two-dimensional Gaussian free field.Our approach is based on a q-analogue of the Schwinger–Dyson (or loop) equations, which originate in the work of Nekrasov and his collaborators, and extends the methods developed by Borodin, Gorin and Guionnet to quadratic lattices.     

Finitely smooth polynomial normal forms of C∞-diffeomorphisms in the neighborhood of a fixed point

Mathematics Institute, Computer Center, Academy of Sciences of the Moldavian SSR. Translated from Funktsional'nyi Analiz i Ego Prilozheniya, Vol. 24, No. 2, pp. 79–80, April–June, 1990.     

Durability of polyurethanes elastomers

The effect of thermal aging on three different elastomeric polyurethane adhesives was studied. Consequently, an attempt was made to predict the polyurethanes' service lifetimes from the changes in tensile properties, hardness of bulk specimens and adhesion strength properties (lap shear and butt joints) of polycarbonate bonded joints. Aging temperatures ranged from ambient to 70 °C (at 50% relative humidity) for durations from 20 days to 18 months. Experimental results were analyzed according to a kinetic rate theory and using limit values for the various properties. Consequently, service lifetimes were determined and compared to results from actual service life. Predictions of long-term performance from accelerated tests proved to be reasonable for the properties and materials studied.     

Double passage analysis in random media using two-scale random propagators

In location and remote sensing experiments there arise a number of effects related to the double passage of the backscattered field through the same random inhomogeneities as the incident one. To account for the correlation of the forward-backward propagating events, there is a need for a measure in which the random information along the propagation path is preserved. For the generation of even statistical moments, the relevant measure defined in the recently formulated stochastic geometrical theory of diflraction is the two-point random function (TPRF)—a paired field measure which is propagated along the geometrical rays of the deterministic background medium. From this function all even statistical moments can be generated. Here we present an approximate analytical solution for the high-frequency propagator obtained by applying the multiscale expansion asymptotic procedure to the partial differential equation governing the propagation a1 the TPRF. The test of the solution is performed on canonical backscattering problems based on point source-point scatterer and paint source-plane mirror configurations, which justifies its further application for construction of the coherence measures of the rctrareflected field. Coherence properties of the plane and spherical wavefields reflected backward by a plane mirror were investigated. Further, we investigated the intensity enhancement effects observed in the double passage of a Gaussian beam retroreflected from a plane mirror. Asymptotic expressions lor the retroreflected intensity are obtained, and their computations show good agreement with the direct numerical evaluations.     

The reference wave solution for a two-frequency wave propagating in a random medium

In this work a new reference wave method for solving parabolic-type equations is proposed. The performance of the method is demonstrated by applying it to the equation governing the propagation of the two-frequency mutual coherence function in a random medium. An analytic solution is presented for arbitrary correlation properties of the medium. It is shown that when approximating the transverse structure function of the medium by a quadratic form, the solution reduces to the exact result derived previously. Extensions to more general types of media are considered.     

Shape-persistent linear, kinked, and cyclic oligo(phenylene-ethynylene-butadiynylene)s: self-assembled monolayers

Shape-persistent rigid phenylene-ethynylene-butadiynylenes form lamellar self-assembled monolayers (SAMs) at the HOPG/TCB interface, which were studied by scanning tunneling microscopy (STM) with submolecular resolution. Substitution of the terminating acetylene functions with polar cyanopropyldimethylsilyl groups leads to 2D phase separation and defined rod-rod interactions, which determine the packing distances between the rigid rods. The results stimulated the connection of rigid rods via septiarylene clamp units. They covalently link two rigid rod units and define the intramolecular rod-rod distance that matches the alkoxy substituent chain lengths. The systems can be described as half-ring structures of two rigid rods connected via a rotatable joint unit. These acetylene-terminated half-ring structures were also oligomerized under Cu and Pd catalysis to yield defined acyclic and cyclic oligomers. Detailed STM studies decoded the molecular origin of the surface patterning of such systems. The dodecyloxy side chains are adsorbed along the HOPG main axes and, together with the alkoxy backbone angle, determine the adsorption direction of the adlayers.