Analysis and numerical simulation of magnetic forces between rigid polygonal bodies. Part I: Analysis

The mathematical and physical analysis of magnetoelastic phenomena is a topic of ongoing research. Different formulae have been proposed to describe the magnetic forces in macroscopic systems. We discuss several of these formulae in the context of rigid magnetized bodies. In case the bodies are in contact, we consider formulae both in the framework of macroscopic electrodynamics and via a multiscale approach, i.e., in a discrete setting of magnetic dipole moments. We give mathematically rigorous proofs for domains of polygonal shape (as well as for more general geometries) in two and three space dimensions. In an accompanying second article, we investigate the formulae in a number of numerical experiments, where we focus on the dependence of the magnetic force on the distance between the bodies and on the case when the two bodies are in contact. The aim of the analysis as well as of the numerical simulation is to contribute to the ongoing debate about which formula describes the magnetic force between macroscopic bodies best and to stimulate corresponding real-life experiments.      

Trimethylaluminum: Bonding by Charge and Current Topology

The charge density distribution of the trimethylaluminum dimer was determined by high‐angle X‐ray diffraction of a single crystal and quantum‐chemical methods and analyzed using the quantum theory of atoms in molecules. The data can be interpreted as Al₂Me₆ being predominantly ionically bonded, with clear indications of topological asymmetry for the bridging Al? C bonds owing to delocalized multicenter bonding. This interpretation is supported by the calculated magnetic response currents. The data shed new light on the bonding situation in this basic organometallic molecule, which was previously described by contradicting interpretations of bonding.     

Two 2,6‐Dioxabicyclo[3.3.1]nonan‐3‐ones from Phragmanthera capitata (Spreng.) Balle (Loranthaceae)

Phytochemical investigation of the leaves of Phragmanthera capitata collected on Cassia spectabilis tree led to the isolation of two natural lactones, rel‐(1R,5S,7S)‐7‐[2‐(4‐hydroxyphenyl)ethyl]‐2,6‐dioxabicyclo[3.3.1]nonan‐3‐one ( 1 ) and 4‐{2‐[rel‐(1R,3R,5S)‐7‐oxo‐2,6‐dioxabicyclo[3.3.1]non‐3‐yl]ethyl}phenyl 3,4,5‐trihydroxybenzoate ( 2 ) together with the known compounds betulinic acid ( 3 ), dodoneine ( 4 ), quercetin 3‐O‐α‐L ‐rhamnopyranoside ( 5 ), quercetin 3‐O‐α‐L ‐arabinofuranoside ( 6 ), quercetin ( 7 ), betulin ( 8 ), lupeol ( 9 ), and sitosterol ( 10 ). Their structures were established by means of modern spectroscopic techniques, and the relative configuration of compound 1 was confirmed by X‐ray analysis. Compounds 1 and 2 were tested in vitro for their antiplasmodial activity against the Plasmodium falciparum chloroquine sensitive‐strains NF54 and 3D7. Compound 2 exhibited good antiplasmodial activity against both strains with IC₅₀ of 2.4 and 4.9 μM , respectively, while compound 1 was inactive.     

A polymer inclusion membrane based on the ionic liquid trihexyl(tetradecyl)phosphonium chloride and PVC for solid–liquid extraction of Zn(II) from hydrochloric acid solution

Abstract  

Extraction of Zn(II) from aqueous solution using polymer inclusion membranes based on poly(vinyl chloride) containing the phosphonium-based ionic liquid trihexyl(tetradecyl)phosphonium chloride (Cyphos^? IL 101) is described. Zn(II) could efficiently be extracted from 5 M hydrochloric acid solution with membranes containing 30 wt% Cyphos IL 101, whereas back-extraction was successfully achieved with 1 M sulfuric acid. Prepared membranes were evaluated in terms of stability in air as well as in terms of leaching of the ionic liquid from the membranes in aqueous solution.