Erratum to: ”Selective separation of some ecotoxic transition metal ions from aqueous solutions using immobilized macrocyclic material containing solid phase extraction system”

The original version of the article was published in Cent. Eur. J. Chem. 9(6) (2011), pp 1019–1026. Unfortunately, the original version of this article contains mistakes in the body of Fig. 1. Here we display the corrected version of the Fig. 1.     

Spectral decomposition and matrix-valued orthogonal polynomials

The relation between the spectral decomposition of a self-adjoint operator which is realizable as a higher order recurrence operator and matrix-valued orthogonal polynomials is investigated. A general construction of such operators from scalar-valued orthogonal polynomials is presented. Two examples of matrix-valued orthogonal polynomials with explicit orthogonality relations and three-term recurrence relation are presented, which both can be considered as 2×2-matrix-valued analogues of subfamilies of Askey–Wilson polynomials.     

The use of additive composition in arithmetic: the case of children classified as low attainers

This study investigated the conceptual understanding that low-attaining children have and are able to use in arithmetic. Fifteen 6–7 year old children solved pairs of conceptually-related addition problems. Conceptual relations between equal problems were constructed to reflect aspects of the principle of additive composition. Children's conceptual understanding was explored by examining their capability to use concept-based approaches in related problems, and ability to recognise and explain additive composition relationships. The findings indicate that, when prompted, children who employ only basic calculation procedures have the capability to recognise and use additive composition relations in problem solving. Almost all children showed increased sensitivity to additive composition relations when asked to explain the equality between related problems. Our findings highlight the need to develop pedagogical approaches that instigate low-attaining children's conceptual capabilities and support the operationalisation of these in the kinds of concept-based strategies that are most typically ascribed to high-attaining children.     

Effect of gamma irradiation on thermoluminescence and thermodynamic parameters of LiKSO4 doped with Nd2 O3

Abstract

The thermoluminescence and thermo-dynamic parameters of LiKSO₄: Nd were investigated. The effect of Nd dopant concentration in the range 0.1-1% as well as that of γ-irradiation dose in the range 56.3-3.24 × 10⁵ Gy were studied. The glow curves of the material are characterized by a double peak; each behaving seperately with radiation dose. The highest TL enhancement was obtained for Nd concentration of 0.5%; while irradiation dose of few hundreds Gy gave the best TL response. The thermodynamic parameters of LiKSO₄ doped with 0.5% Nd decreased with radiation dose up to about 5000 Gy.     

Diffusion of small penetrant molecules in polybutadienes

The diffusion coefficient D in the dilute limit for three different penetrants – oxygen, water, and methanol – in three different conformations of polybutadiene (all cis-1,4, all trans-1,4, and a random copolymer containing 50% trans-1,4, 40% cis-1,4, and 10% vinyl-1,2 repeat units) has been computed using molecular dynamics simulations for temperatures in the range T?=?300–400?K. Simulation runs of 25 and 50?ns were made for each of the 45 combinations of penetrant, conformation, and temperature studied. Over this temperature range the density of the all-cis-1,4 conformation is higher than that of the all-trans-1,4 and random copolymer conformations, which are approximately equal. For all three conformations, D for oxygen and water are comparable and larger than that of methanol. However for a given penetrant, strong differences were observed in the rate of increase of D for the three conformations. We find that the activation barriers for the three penetrants are generally between 20 and 30?kJ?mol^?1, in agreement with experimental results. The magnitude of the activation energy is directly proportional to the size, rather than the mass, of the penetrant molecule.     

Acutaxylines A and B, two novel triterpenes from Dysoxylum acutangulum

Two novel triterpenes, acutaxylines A (1) and B (2) consisting of a cyclopentenone side chain at C-17 and an oxepan-2-ol, were isolated from the leaves of Dysoxylum acutangulum. The relative stereochemistry of 1 and 2 was determined by NOESY correlations. Acutaxyline B showed moderate cytotoxicity against human blood premyelocytic leukemia cells.     

Preface

Preface

Preface     

Application of multi-element clustering techniques of five Egyptian industrial sugar products

The concentration of 18 elements in different cane sugar products, i.e., cane sugar plants, crude and syrup juices, molasses, and the end products of the consumer sugar, were analyzed and processed. The samples were collected from five citics, i.e., Kom Ombo, Edfu, Armant, Deshna and Naga Hammady in Upper Egypt where the main Egyptian sugar industry factories are located. INAA was applied for the determination of Al, Ca, Cl, Co, Cr, Fe, Mg, Mn, Na and Sc, while Cu, Li, P, Sn, V and Zn were determined by ICP-AES and Pb and As were determined by AAS. These three analytical methods were applied to optimize the sensitivity and the accuracy of the measurements in order to provide a sound basis for the obtention of reliable clustering results.