A new dimeric alkylresorcinol from the stem barks of Swintonia floribunda (Anacardiaceae)

From an EtOAc-soluble fraction of the stem barks of Swintonia floribunda (Anacardiaceae), one new dimeric alkylresorcinol named integracin E (1), together with 4 known compounds (2–5) were isolated. Their chemical structures were elucidated based on the spectroscopic data interpretation. The absolute configuration of 1 was determined by the specific rotation analysis of its acid-catalyzed hydrolysis product. Compound 1 showed potent tyrosinase inhibitory activity with an IC₅₀ value of 48.2?μM.     

SIMS of organic layers with unknown matrix parameters: Locating the interface in dual beam argon gas cluster depth profiles

Four simple methods are evaluated to determine their accuracies for establishing the interface location in secondary ion mass spectrometry intensity depth profiles of organic layers where matrix effects have not been measured. Accurate location requires the separate measurement of each ion's matrix factor. This is often not possible, and so estimates using matrix-less methods are required. Six pure organic material interfaces are measured using many secondary ions to compare their locations from the four methods with those from full evaluation with matrix terms. For different secondary ions, matrix effects cause the apparent interface positions to vary over 20 nm. The shifts in the intensity profiles on going from a layer of P into a layer of Q are in the opposite direction to that for going from Q into P, so doubling layer thickness errors. The four methods are as follows: M1, use of the median interface position in the intensity profiles for the five lightest ions for 15 ≤ m/z ≤ 150; M2, extrapolation of the position for each ion to m/z = 0 for ions with m/z ≤ 150; M3, as M2 but for m/z ≤ 300; and M4, the extreme positions for all m/z ≤ 100. Comparison with the location using matrix terms shows their ranking, from best to worst, to be M4, M3, M1, and M2 with average errors of 10%, 12%, 14%, and 17%, respectively, of the profile interface full widths at half maximum. Use of pseudo-molecular ions is very much poorer, exceeding 50%, and should be avoided.     

Crystallization of Calcium Phosphates from the Prototype of Blood Plasma in the Presence of Inorganic and Organic Impurities

Crystallography Reports - The crystallization processes in solutions modeling the human blood plasma composition have been investigated. It is revealed that the solid phases consist of OH-deficient...     

Sorption and Selective Properties of Diatomite Adsorbents for Gas Chromatography,Modified by a Cu(II) Complex of a Camphor-Substituted Tetrapyrasinoporphyrazine

Russian Journal of General Chemistry - Modified adsorbents for gas chromatography were prepared using a Cu(II) complex of a camphorsabstituted tetrapyrasinoporphyrazine. The thermal stability of...     

Synthesis of Alkylphosphoryl-Containing 4(5)-Arylimidazolin-2-ones

Russian Journal of General Chemistry - The acid-catalyzed reaction of {2-[1-(2,2-dimethoxyethyl)-3-(phenylcarboxamido)]ethyl}phosphonate or diethyl...     

Properties of Polyurethanes Prepared by Structuring Oligodienediols at Double Bonds and Hydroxyl Groups

The curing of oligodienediol with a combined system consisting of a polyisocyanate and a (meth)acrylate-containing compound, which allows it to be structured with the polyisocyanate both at the terminal hydroxyl groups and double bonds due to the (meth)acrylate component, has been studied. The effect of the concentration of the (meth)acrylate component and a peroxide initiator to the degree of cross linking and strength properties of elastomers has been revealed. It has been shown that the participation of oligomer double bonds to form a vulcanization structure, creating the effect of “healing” defects from functional heterogeneity, allows one to increase the degree of cross linking and strength properties of polyurethanes.     

Estimates of the Best Approximation of Polynomials by Simple Partial Fractions

An asymptotics of the error of interpolation of real constants at Chebyshev nodes is obtained. Some well-known estimates of the best approximation by simple partial fractions (logarithmic derivatives of algebraic polynomials) of real constants in the closed interval [?1, 1] and complex constants in the unit disk are refined. As a consequence, new estimates of the best approximation of real polynomials on closed intervals of the real axis and of complex polynomials on arbitrary compact sets are obtained.

     

The Synergistic Effect of a Mixture of the Oligomer of 2,2,4-Trimethyl-1,2-Digidrochinoline and Polymeric Petroleum Resin on the Adhesion of Chlorobutyl Rubber to Steel

Studies have been carried out to increase the adhesion and heat resistance of insulating tape coatings based on chlorobutyl rubber applied on pipelines. It is shown that the synergistic effect of the growth of adhesion of chlorobutyl rubber to steel by the co-administration of the oligomer of 2,2,4-trimethyl-1,2-dihydroquinoline and polymeric petroleum resin is due to the increased interaction of the oligomer with chlorobutyl rubber under the action of a polymeric petroleum resin and the high adhesion of the oligomer to steel.     

An adaptive multilevel wavelet framework for scale‐selective WENO reconstruction schemes

We put forth a dynamic computing framework for scale‐selective adaptation of weighted essential nonoscillatory (WENO) schemes for the simulation of hyperbolic conservation laws exhibiting strong discontinuities. A multilevel wavelet‐based multiresolution procedure, embedded in a conservative finite volume formulation, is used for a twofold purpose. (i) a dynamic grid adaptation of the solution field for redistributing grid points optimally (in some sense) according to the underlying flow structures, and (ii) a dynamic minimization of the in built artificial dissipation of WENO schemes. Taking advantage of the structure detection properties of this multiresolution algorithm, the nonlinear weights of the conventional WENO implementation are selectively modified to ensure lower dissipation in smoother areas. This modification is implemented through a linear transition from the fifth‐order upwind stencil at the coarsest regions of the adaptive grid to a fully nonlinear fifth‐order WENO scheme at areas of high irregularity. Therefore, our computing algorithm consists of a dynamic grid adaptation strategy, a scale‐selective state reconstruction, a conservative flux calculation, and a total variation diminishing Runge‐Kutta scheme for time advancement. Results are presented for canonical examples drawn from the inviscid Burgers, shallow water, Euler, and magnetohydrodynamic equations. Our findings represent a novel direction for providing a scale‐selective dissipation process without a compromise on shock capturing behavior for conservation laws, which would be a strong contender for dynamic implicit large eddy simulation approaches.     

Semigroup Classification and Gelfand–Shilov Classification of Systems of Partial Differential Equations

Mathematical Notes - Two approaches to systems of linear partial differential equations are considered: the traditional approach based on the generalized Fourier transform and the semigroup...