Lanthanide‐IMAC enrichment of carbohydrates and polyols

In this study a new type of immobilized metal ion affinity chromatography resin for the enrichment of carbohydrates and polyols was synthesized by radical polymerization reaction of vinyl phosphonic acid and 1,4‐butandiole dimethacrylate using azo‐bis‐isobutyronitrile as radical initiator. Interaction between the chelated trivalent lanthanide ions and negatively charged hydroxyl groups of carbohydrates and polyols was observed by applying high pH values. The new method was evaluated by single standard solutions, mixtures of standards, honey and a more complex extract of Cynara scolymus. The washing step was accomplished by acetonitrile in excess volumes. Elution of enriched carbohydrates was successfully performed with deionized water. The subsequent analysis was carried out with matrix‐free laser desorption/ionization–time of flight mass spectrometry involving a TiO₂‐coated steel target, especially suitable for the measurement of low‐molecular‐weight substances. Quantitative analysis of the sugar alcohol xylitol as well as the determination of the maximal loading capacity was performed by gas chromatography in conjunction with mass spectrometric detection after chemical derivatization. In a parallel approach quantum mechanical geometry optimizations were performed in order to compare the coordination behavior of various trivalent lanthanide ions. Copyright © 2013 John Wiley & Sons, Ltd.     

Analysis of Concatenations and Order of Operations in Written Mathematics

Concatenations in written mathematics are the positioning of symbols next to each other to imply an operation without a symbol for the operation. Concatenations have been identified in previous research as an obstacle to understanding, or a cognitive difficulty, in the learning of algebra. The additive inverse symbol with concatenations poses questions not addressed by the usual conventions for order of operations. In this study, texts of grades 6 through 9 were surveyed, and quantitative and qualitative analyses were made of the instructional emphasis on selected concatenations. Results indicated much curricular emphasis on unsigned (without negative signs) numeral forms and integer, as compared to minimal curricular emphasis on signed (with negative signs) fraction, mixed number, decimal, and exponent numeral forms. A recommendation is to increase curricular emphasis on signed numeral forms and to include the additive inverse unary operation in the conventional order of operations.     

A Symmetric Galerkin Boundary Element Method for Linear Poroelasticity

In linear poroelasticity so far only collocation boundary element methods have been available. However, in some applications, e.g., when coupling with finite elements is desired, a symmetric formulation is preferable. Choosing a Galerkin approach which involves the second boundary integral equation, such a formulation is possible. Here, a previously presented integration by part technique for the regularization of the first boundary integral equation is extended to the second boundary integral equation as well. While the weakly singular representation of the double layer operator has been presented before, the emphasis lies here on the so called hyper-singular boundary integral operator. Due to the regularization, this operator can be evaluated numerically and, hence, be used within a numerical scheme for the first time. Different numerical studies will be presented to show the behavior of the established symmetric Galerkin boundary element method, also comparing it with collocation boundary element methods. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Measurement of50V and51V nuclear moments by nuclear magnetic resonance methods

From measurements of the Larmor frequencies of²H,⁵⁰V and⁵¹V in aqueous vanadate solution the ratio of theg _I-factors of⁵⁰V and⁵¹V and the nuclear magnetic moments of⁵⁰V and⁵¹V are derived. The ratio of the longitudinal relaxation times T₁ in VOCl₃ yields the ratio of the quadrupole moments |Q(⁵⁰V)/Q(⁵¹V)|=(3.99±0.14). In the 3d ³ 4s ^{2 4} F _3/2 atomic ground state the hyperfine structure anomaly is smaller than 1·10^?5.     

Limits on D0-D0 mixing and bottom particle production cross section from hadronically produced same-sign dimuon events

The rates for same-sign and opposite-sign dimuon events with missing energy (indicative of final-state neutrinos) have been measured in 278 GeV π^?-Fe and 350 GeV proton-Fe collisions. The main source of opposite-sign events is two semi-leptonic decays of hadronically produced charm states. The same-sign events are consistent with background from pion and kaon decays. We obtain a limit of 0.044 (90% CL) on the fraction of D⁰ semileptonic decays that result in the wrong-sign muon and conclude that less than 9% (90% CL) of same-sign dimuon events produced in neutrino interactions can be attributed to D⁰-$\text{D}$⁰ mixing. The data imply δm < 6.5 × 10^?4 eV and $\text{δλ}\text{λ}\text{< 0.55}$ for the difference in mass and inverse lifetime of the CP eigenstates of the D⁰. Limits on diffractive bottom production cross sections in proton and pion collisions are also presented.