Instrumental neutron activation analysis of pottery for provenience study

A scheme for INAA of pottery is proposed. The combination of 3 irradiations-epithermal and pile (short and long time) and 6 measurements (2 times after each irradiation) enables the determination of Al, As, Au, Ba, Br, Ce, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Si, Sm, Ta, Tb, Th, Ti, U, V and Yb. The accuracy and precision of the method is evaluated by analysis of standard reference materials (USGS-BCR-1, USGS-W-1, ZGI-TB). The applicability of the method is demonstrated by analysis of 15 sgraffito ceramics from XV–XVIII cc. from Tzarevetz, Veliko Tirnovo (Bulgaria). The results from the clustering of the analytical data are presented and discussed.     

Determination of zinc in clay and pottery materials by instrumental neutron activation analysis

The problems of determination of zinc in clay, ceramics and soils via ⁶⁵Zn using INAA are discussed. The applicability of different approaches for solving the influence of ⁴⁶Sc and ¹⁵²Eu by gamma-spectrometry on the line of ⁶⁵Zn at 1115.5 keV are experimentally evaluated. The application of the correction program ANGES for the calculation of the net peak area is demonstrated. All discussed approaches are checked by analyses of 10 SRM"s: Ohio Red Clay, Lefkandi brick, IAEA-SRM-Soil-1, IAEA-SRM-Soil-5, IAEA-SRM-Soil-7, IAEA-SRM-SL-3, GBW-08303, GBW-07406, NIST-SRM-2709 and BCR-SRM-520.     

Derivation of shell effects and magic numbers in metal clusters by the application of Strutinsky's method to the Clemenger–Nilsson and q‐deformed 3‐D harmonic oscillator models

Strutinsky's standard averaging method is applied to metal clusters described by two different potentials—Clemenger–Nilsson (CN) and q‐deformed 3‐D (Q3D) harmonic oscillator (HO). In addition, a new approximate fitting formula—of the liquid drop model type—is derived for the smooth part of the energy. The results obtained for the oscillating part of the energy (shell correction term) with the two cluster potentials through the two averaging methods are compared and discussed. It is found that with both CN and Q3D HO potentials the standard and approximate methods give similar results for clusters with a large number of particles, whereas for smaller clusters significant differences appear. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002     

Letters to the Editor Instrumental Neutron Activation Analysis of Medieval Glasses from the First Bulgarian Capital – Pliska (9th Century)

Ion exchange chromatography of boric acid was carried out using an anion exchange resin in fluoride and chloride forms in order to investigate the temperature dependence of separation factor (S) for boron isotopes. The results are summarized as follows: For the fluoride form resin system, S? 1 = 1348/T² ? 0.0051 (between 5 °C and 35 °C) and for the chloride form resin system, S? 1 = 645/T² ? 0.0053 (between 5 °C and 50 °C) where T is the temperature in units of K.     

Tagungsberichte

Some analytical procedures for the determination of tritium, strontium-90 and iodine-129 in liquid radioactive wastes from nuclear power plants of the type WWER-440 are described. Liquid scintillation counters (³H), beta-counters applying an Al-absorber (⁹⁰Sr) and neutron activation analysis (¹²⁹I) applying a suitable separation process are used. The results are discussed with respect to the waste management manufactured in future and the deposition of radioactive wastes coming from the nuclear power station “Kozloduj”.     

The minimized dead-end elimination criterion and its application to protein redesign in a hybrid scoring and search algorithm for computing partition functions over molecular ensembles

One of the main challenges for protein redesign is the efficient evaluation of a combinatorial number of candidate structures. The modeling of protein flexibility, typically by using a rotamer library of commonly-observed low-energy side-chain conformations, further increases the complexity of the redesign problem. A dominant algorithm for protein redesign is dead-end elimination (DEE), which prunes the majority of candidate conformations by eliminating rigid rotamers that provably are not part of the global minimum energy conformation (GMEC). The identified GMEC consists of rigid rotamers (i.e., rotamers that have not been energy-minimized) and is thus referred to as the rigid-GMEC. As a postprocessing step, the conformations that survive DEE may be energy-minimized. When energy minimization is performed after pruning with DEE, the combined protein design process becomes heuristic, and is no longer provably accurate: a conformation that is pruned using rigid-rotamer energies may subsequently minimize to a lower energy than the rigid-GMEC. That is, the rigid-GMEC and the conformation with the lowest energy among all energy-minimized conformations (the minimized-GMEC) are likely to be different. While the traditional DEE algorithm succeeds in not pruning rotamers that are part of the rigid-GMEC, it makes no guarantees regarding the identification of the minimized-GMEC. In this paper we derive a novel, provable, and efficient DEE-like algorithm, called minimized-DEE (MinDEE), that guarantees that rotamers belonging to the minimized-GMEC will not be pruned, while still pruning a combinatorial number of conformations. We show that MinDEE is useful not only in identifying the minimized-GMEC, but also as a filter in an ensemble-based scoring and search algorithm for protein redesign that exploits energy-minimized conformations. We compare our results both to our previous computational predictions of protein designs and to biological activity assays of predicted protein mutants. Our provable and efficient minimized-DEE algorithm is applicable in protein redesign, protein-ligand binding prediction, and computer-aided drug design.     

Exploring interatomic Coulombic decay by free electron lasers

To exploit the high intensity of laser radiation, we propose to select frequencies at which single-photon absorption is of too low energy and two or more photons are needed to produce states of an atom that can undergo interatomic Coulombic decay (ICD) with its neighbors. For Ne(2) it is explicitly demonstrated that the proposed multiphoton absorption scheme is much more efficient than schemes used until now, which rely on single-photon absorption. Extensive calculations on Ne(2) show how the low-energy ICD electrons and Ne(+) pairs are produced for different laser intensities and pulse durations. At higher intensities the production of Ne(+) pairs by successive ionization of the two atoms becomes competitive and the respective emitted electrons interfere with the ICD electrons. It is also shown that a measurement after a time delay can be used to determine the contribution of ICD even at high laser intensity.     

Comparative evaluation of the possibilities of INAA, ED-XRF, ICP-AES and AAS in the analysis of plants

The usefulness of INAA, radionuclide ED-XRF, ICP-AES and AAS are comparatively evaluated for the determination of nutrients, essential and trace elements in various plant matrices. The comparison is performed by analysis of the following reference materials: NIST-SRM-1573, NIST-SRM-1575, NIES-1, NIES-3, NIES-6, IAEA-V-10 and Bowen's kale. The detection limits, accuracy and precision of the methods are discussed and a combination of INAA and GFAAS is recommended for analysis of plants for monitoring purposes.