Catalysis of radical reactions in mixed micelles of surfactants with hydroperoxides

The peculiarities of the catalytic action of cationic surfactants (CSurf) in combination with hydroperoxides on the generation of radicals and the influence of various factors on this process (transition metal compounds, oxygen, and external magnetic field) were considered. In the oxidized hydrocarbons (RH), hydroperoxides (ROOH), which are the primary amphiphilic products of oxidation, form mixed micelles {mROOH…nCSurf} with CSurf, in which fast decomposition of ROOH into radicals occurs and other polar components (metal compounds, inhibitors, etc.) can concentrate, which significantly affects the rate and mechanism of oxidation. The cationic surfactants immobilized on a solid support retain the ability to catalyze the decomposition of hydroperoxides, forming radicals, and to initiate radical oxidation and polymerization. It was found that acetylcholine, which is the most important neurotransmitter that plays an important role in the neuromuscular and cognitive activity of living beings, like cationic surfactants, catalyzes the radical decomposition of hydroperoxides in organic media, and the yield of radicals in this process decreases in a magnetic field and in the presence of oxygen.     

A rare earth metallocene containing a 2,2′-azopyridyl radical anion

Introducing spin onto organic ligands that are coordinated to rare earth metal ions allows direct exchange with metal spin centres. This is particularly relevant for the deeply buried 4f-orbitals of the lanthanide ions that can give rise to unparalleled magnetic properties. For efficacy of exchange coupling, the donor atoms of the radical ligand require high-spin density. Such molecules are extremely rare owing to their reactive nature that renders isolation and purification difficult. Here, we demonstrate that a 2,2′-azopyridyl (abpy) radical (S = 1/2) bound to the rare earth metal yttrium can be realized. This molecule represents the first rare earth metal complex containing an abpy radical and is unambigously characterized by X-ray crystallography, NMR, UV-Vis-NIR, and IR spectroscopy. In addition, the most stable isotope ⁸⁹Y with a natural abundance of 100% and a nuclear spin of ½ allows an in-depth analysis of the yttrium–radical complex via EPR and HYSCORE spectroscopy. Further insight into the electronic ground state of the radical azobispyridine-coordinated metal complex was realized through unrestricted DFT calculations, which suggests that the unpaired spin density of the SOMO is heavily localized on the azo and pyridyl nitrogen atoms. The experimental results are supported by NBO calculations and give a comprehensive picture of the spin density of the azopyridyl ancillary ligand. This unexplored azopyridyl radical anion in heavy element chemistry bears crucial implications for the design of molecule-based magnets particularly comprising anisotropic lanthanide ions.

Unambiguous characterization of the first 2,2′-azobispyridine radical-containing rare earth metal complex through X-ray crystallography, DFT computations, EPR and HYSCORE spectroscopy.     

Discussion

Abstract

Visualization is increasingly being recognized as an effective and efficient way not only to communicate patterns in scientific data, but to discover them as well. In the low dimensions of everyday experience, the human ability to find meaningful order in noisy data may never be matched by automatons. So the introduction of a useful visualization procedure, as provided here by Furnas and Buja, is indeed a welcome development. They show that low-dimensional patterns extracted by a combined projection and section operation (a prosection) can imply the existence of similar higher-dimensional structure. In exploratory or inductive data analyses, then, prosections could be used to generate hypotheses about relationships between sampled variables. However, the familiar curse of dimensionality may confine their practical application to point clouds of only moderate dimension.     

Colloidal catalysts based on iron(III) oxides. 2. Peculiarities of catalyzed oxidation of palm oil

The catalytic activity of an iron(III)-oxide-based colloidal catalyst with respect to oxidation of palm oil with atmospheric oxygen at 60°C is investigated. In a microheterogeneous system of palm oil containing phospholipids and large amounts of ??-tocopherol and ??-carotene, oxidation in the presence of the catalyst proceeds by a latent radical mechanism. This mechanism manifests itself as oxygen uptake against a background of almost constant concentrations of natural antioxidants, i.e., ??-tocopherol and ??-carotene. Using a model reaction of oxidation of an individual natural olefin, limonene, it is shown that, in the presence of the catalyst and trace amounts of hydroperoxide, oxidation of the hydrocarbon occurs through the chain free-radical mechanism. The presence of a phospholipid (egg lecithin) dramatically decelerates the catalytic oxidation of limonene and makes the process proceed through the latent radical mechanism, the rate of which is unaffected by oil-soluble inhibitors.     

Link distance and shortest path problems in the plane

This paper describes algorithms to compute Voronoi diagrams, shortest path maps, the Hausdorff distance, and the Fréchet distance in the plane with polygonal obstacles. The underlying distance measures for these algorithms are either shortest path distances or link distances. The link distance between a pair of points is the minimum number of edges needed to connect the two points with a polygonal path that avoids a set of obstacles. The motivation for minimizing the number of edges on a path comes from robotic motions and wireless communications because turns are more difficult in these settings than straight movements.Link-based Voronoi diagrams are different from traditional Voronoi diagrams because a query point in the interior of a Voronoi face can have multiple nearest sites. Our site-based Voronoi diagram ensures that all points in a face have the same set of nearest sites. Our distance-based Voronoi diagram ensures that all points in a face have the same distance to a nearest site.The shortest path maps in this paper support queries from any source point on a fixed line segment. This is a middle-ground approach because traditional shortest path maps typically support queries from either a fixed point or from all possible points in the plane.The Hausdorff distance and Fréchet distance are fundamental similarity metrics for shape matching. This paper shows how to compute new variations of these metrics using shortest paths or link-based paths that avoid polygonal obstacles in the plane.     

Human Neuroepithelial Cells Express NMDA Receptors

L-glutamate, an excitatory neurotransmitter, binds to both ionotropic and metabotropic glutamate receptors. In certain parts of the brain the BBB contains two normally impermeable barriers: 1) cerebral endothelial barrier and 2) cerebral epithelial barrier. Human cerebral endothelial cells express NMDA receptors; however, to date, human cerebral epithelial cells (neuroepithelial cells) have not been shown to express NMDA receptor message or protein. In this study, human hypothalamic sections were examined for NMDA receptors (NMDAR) expression via immunohistochemistry and murine neuroepithelial cell line (V1) were examined for NMDAR via RT-PCR and Western analysis. We found that human cerebral epithelium express protein and cultured mouse neuroepithelial cells express both mRNA and protein for the NMDA receptor. These findings may have important consequences for neuroepithelial responses during excitotoxicity and in disease.