The compound (bpy) 2Mn (III)(mu-O) 2Mn (IV)(bpy) 2, a structural model relevant for the photosynthetic water oxidation complex, was coupled to single Cr (VI) charge-transfer chromophores in the channels of the nanoporous oxide AlMCM-41. Mn K-edge EXAFS spectroscopy confirmed that the di-mu-oxo dinuclear Mn core of the complex is unaffected when loaded into the nanoscale pores. Observation of th...

The aim of feed formulation in aquaculture is to supply a suitable diet that provides nutritional requirements at relatively low cost. Carbohydrates are the most economic energy source for animals compared to protein and lipid; however, fish have limited capacity for dietary carbohydrate utilization. Trivalent chromium is an essential micronutrient for carbohydrate metabolism in vertebrates. Th...

The crystal structure of [Cr(NCS)2(cyclam)]NCS (cyclam = 1,4,8,11-tetra-aza-cyclo-tetra-deca-ne, C10H24N4) has been determined by using synchrotron radiation at 98 K. The Cr(III) atom is in a slightly distorted octa-hedral environment with four N atoms of the macrocyclic ligand and two N-coordinated NCS(-) anions in cis positions. The average Cr-N(cyclam) and Cr-NCS bond lengths are 2.085 (5) a...

Cr(VI) genotoxicity is caused by products of its reductive metabolism inside the cells. Reactive oxygen species (ROS) and Cr(V,IV) intermediates are potential sources of oxidative damage by Cr(VI). Here, we investigated seven fluorescent probes for the detection of ROS and non-ROS oxidants in Cr(VI) reactions with its main reducers. We found that Cr(V)-skipping metabolism of Cr(VI) by ascorbate...

The reaction of the tris(tetradentate) triplesalen ligand H6talen 2, which provides three salen-like coordination environments bridged in a meta-phenylene arrangement by a phloroglucinol backbone, with Mn salts under aerobic conditions, affords, in situ, the trinuclear Mn triplesalen complex [(talen){Mn(solv)n}3] . This species then reacts with [(Me3tacn)Cr(CN)3] to form the tetranuclear comple...

In this paper we discuss some structure problems regarding the foliation of Levi flat manifolds, i.e. those CR manifolds which are foliated by complex leaves or, equivalently, whose Levi form vanishes. Levi flat manifolds have a particular significance among CR manifolds, since due to their degenerate nature they often behave as “limit case”, or they are an obstruction in extension problems of ...

Let M̄ be a complex space form of constant holomorphic sectional curvature c and let M be an n-dimensional CR-submanifold of (n− 1) CR-dimension in M̄. ThenM has an almost contact metric structure (F,U ,u,g) (see Section 2) induced from the canonical complex structure of M̄. Hence on an n-dimensional CR-submanifold of (n− 1) CRdimension, we can consider two structures, namely, almost contact struc...

1 Department of Mathematics, Faculty of Science, University of Žilina, Univerzitná 8215/1, 01026 Žilina, Slovakia 2 Institute of Mathematics, National Academy of Sciences of Ukraine, Tereshchenkovskaya Str. 3, 01601 Kyiv, Ukraine 3 Department of Mathematics and Descriptive Geometry, Faculty of Civil Engineering, Brno University of Technology, Veveřı́ 331/95, 60200 Brno, Czech Republic 4 Departme...

On conformal manifolds of even dimension n ≥ 4 we construct a family of new conformally invariant differential complexes, each containing one coboundary operator of order greater than 1. Each bundle in each of these complexes appears either in the de Rham complex or in its dual (which is a different complex in the non-orientable case). Each of the new complexes is elliptic in case the conformal...

A new method involving pre-concentration on modified silica fiber is described for the speciation of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] in aqueous media. This method is based on the different chelating behavior of Cr(III) and Cr(VI) with morpholine-4-carbodithioate (MDTC). Both complexes are extracted on silica fiber modified by sol-gel technology by using 3-aminopropyltriethoxys...