Fixation of actinide elements into zeolites/zeotypes and Flexcrete-cement matrix

The leaching behavior of -emitter radionuclides (uranium and americium) from zeolite-L and the zeotype (SAPO-34) in a Flexcrete-cement matrix were examined by static and dynamic methods using 0.005M CaCl₂ and synthetic ground water as leachants. The leaching rates of UO ₂ ²⁺ were found to be higher by about ten orders of magnitude than those of Am³⁺ for both zeolite-L and SAPO-34 in the cement matrix. The static and dynamic leaching rates of UO ₂ ²⁺ for SAPO-34 in CaCl₂ and synthetic ground water were ten orders of magnitude lower than those for L. SAPO-34 showed good selectivity for uranium at pH 2–3.5 and L was usefully selective for Am³⁺. Distribution coefficients of Am³⁺ and UO ₂ ²⁺ increased with equilibrium pH.     

The Use of Natural Zeolites for Radioactive Waste Treatment: Studies on Leaching from Zeolite/Cement Composites

Samples of the natural zeolites chabazite, clinoptilolite and a clinoptilolite-rich tuff, were loaded with the isotope ¹³⁷Cs. Composites of these labeled materials were made with cement and blast furnace slag. Standard leaching experiments were carried out with synthetic sea, ground and "pond" waters, as well as distilled water. Rates of leaching were calculated and compared to similar systems.     

An automated fuel element scanning system

This paper describes an automated fuel element scanning system, based upon gamma-ray spectroscopy, that has been developed at the Oak Ridge Research Reactor. The scanning system is located in the reactor pool and allows fuel elements to be scanned nondestructively at various intervals during their core life. Fuel elements are located 430 cm beneath the pool. Gamma-ray measurements (aided by a collimating assembly) are made using a GeLi detector positioned above the pool water. Measurements of¹³⁷Cs count rates from relatively cold elements indicate that the counting data obtained using this apparatus is reproducible within 5%. Power distribution in the reactor's core (element by element) has been derived from¹⁴⁰La counting data. The method of determining power is discussed briefly and some example results are presented.     

Paley graphs have Hamilton decompositions

We prove that all Paley graphs can be decomposed into Hamilton cycles.     

Calculating surrogate constraints

Various theoretical properties of the surrogate dual of a mathematical programming problem are discussed, including some connections with the Lagrangean dual. Two algorithms for solving the surrogate dual, suggested by analogy with Lagrangean optimisation, are described and proofs of their convergence given. A simple example is solved using each method.     

Analyse von Preussisch-Blau

Ohne Zusammenfassung     

Partitioning heuristics for two geometric maximization problems

Given n points randomly selected from a uniform distribution on the unit square, we describe linear-time partitioning heuristics which will construct a matching or a tour of these points. We show that the heuristics closely approximate the optimum values as n → ∞. Hence we show that the asymptotic values of the maximum matching and tour are about 0·3826n and twice this value respectively.     

Probabilistic analysis of a parallel algorithm for finding the lexicographically first depth first search tree in a dense random graph

We describe an O((log n)²) time parallel algorithm, using n processors, for finding the lexicographically first depth first search tree in the random graph G _{n, p}, with p fixed. The problem itself is complete for P, and so is unlikely to be efficiently parallelizable always.     

Characterisation of low abundance wool proteins through novel differential extraction techniques

Fibres from human hair and wool are characterised by two main types of proteins: intermediate filament proteins (IFPs) and keratin associated proteins (KAPs). The IFPs, comprising over 50% of the fibre, tend to dominate 2‐D electrophoretic maps, hindering identification of the less‐abundant KAPs. This has been compounded in wool fibres by the relatively limited amount of sequence information available, with approximately 35 distinct protein sequences from ten KAP families being available, in contrast to human hair, where the sequences from well over 80 proteins from 26 KAP families are known. Additional complications include the high degree of homology within these families, ranging from 70 to 95%, and the dominance of cysteine residues in a number of KAP families with their high propensity to form cross‐links. The lack of sequence information for wool KAPs has been partly overcome through the recent acquisition of new sequences. Fractionation of the proteins on the basis of their solubility with pH, urea and DTT concentration has resulted in protein extracts in which the IFP concentration has been considerably reduced. These improvements have enabled the identification of low‐abundance proteins in 2‐D electrophoretic maps and represent a significant advance in our knowledge of the wool proteome.