ContinuousK-theory

We study arithmetical properties of homotopy groups of thel-adic completion of Quillen'sK-theory space of number field, with a view on the Dwyer-Friedlander comparison map into étaleK-theory. The relation of these groups toK-theory is a complete analogy to the relation of continuous étale cohomology to étale cohomology. We identify the torsion subgroup of the resulting term with the subgroup of divisible elements inK _2n (F). We prove that this term is sent isomorphically into étaleK-theory, giving some further evidence for the Lichtenbaum-Quillen conjectures.     

The steric structure of multiflorine methylation products

Summary Multiflorine (1) — a minor lupine alkaloid — treated by methyl lithium or methyl magnesium iodide affords 4S-4-hydroxy-4-methyl-2,3-didehydrosparteine (2) and 2S-2-methyl-4-oxosparteine (3), respectively, as the dominating products. Their steric structure, determined by¹H and¹³C NMR techniques, points to stereospecific preferences of these reactions. The observed nucleophilic 1,2- and 1,4-additions indicate that regiospecificity of the action of MeLi or MeMgI on multiflorine is different from that of the so far known similar alkylation of other enamino ketones.

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Die räumliche Struktur von Methylierungsprodukten des Multiflorins

Zusammenfassung Multiflorin (1), ein Lupin-Nebenalkaloid, ergibt bei Umsetzung mit Methyllithium oder Methylmagnesiumiodid 4S-4-Hydroxy-4-methyl-2,3-didehydrospartein (2) und 2S-2-Methyl-4-oxospartein (3) als Hauptprodukte. Ihre NMR-spektroskopisch (¹H und¹³C) aufgeklärte räumliche Struktur weist auf eine Stereoselektivität der erwähnten Reaktionen hin. Die beobachteten nucleophilen 1,2- und 1,4-Additionen zeigen, daß sich die Regiospezifität der Einwirkung von MeLi oder MeMgl auf Multiflorin von jener bis jetzt bekannter Alkylierungen von Enaminoketonen unterscheidet.

     

Europium isotope separation in the HCl/HDEHP extraction system

The^153/151Eu isotope separation factor (q) for the Eu(II)/Eu(III) chemical exchange in the liquid-liquid extraction system, containing Eu (III) in di (2-ethylhexyl) phosphoric acid (HDEHP) and Eu(II) in water acidified with hydrochloric acid, was found to be 0.9993±0.0002 (2) for the single stage. Some theoretical aspects of separation of the Eu isotopes are discussed. The decisive role of the electron exchange reaction and complexation by the counter-ion in the aqueous phase is emphasized.     

Influence of substituents on positron annihilation in styrene copolymers

Results of angular correlation of annihilation radiation (ACAR) and positron annihilation lifetime (PAL) measurements are presented for five styrene copolymers: poly(co-styrene-phenylmaleimide) and its three derivatives with chlorine as well as for one with the OH group substituted at the benzene ring. It occurs that the chlorine substituted at three different positions at the benzene ring poly(co-styrene-o (or-m,-p)-chlorophenylmaleimide) inhibits the formation of the positronium to different extent. The greatest effect is observed in case of the chlorine atom substituted at the benzene ring at the ortho-position towards the nitrogen atom. The two long lifetimes (₃ and ₄) observed in the lifetime spectra are connected with the bimodal distributions of the free volume radius in the samples.     

A definitive method for the determination of trace amounts of cobalt in biological materials by neutron activation analysis

A new, very accurate (definitive) method for the determination of trace amounts of cobalt in biological materials has been devised. The method is based on combination of neutron irradiation with quantitative and selective post-irradiation separation of cobalt from all accompanying radionuclides followed by measurement by -ray spectrometry. Column chromatography in which owing to addition of Co carrier the course of separation can be followed visually is the key element of the separation scheme. Several criteria have been formulated which must be simultaneously fulfilled in order to acknowledge the result as obtained by a definitive method. The high accuracy of the method has been demonstrated by the analysis of several certified reference materials of widely different Co contents.     

Atomic absorption spectrophotometric determination of gold with preconcentration by Donnan dialysis

Donnan dialysis enrichment with tubular cation-exchange membrane was used as a preconcentration method prior to determination of gold by flame atomic absorption spectrometry (FAAS). The value of enrichment factor can be controlled for a particular application through adjustment of the membrane tuning length, dialysis time, carrier flow rate, composition of the receiver solution and by addition of complexing ligand to the receiver or the sample solution. For 10 min dialysis enrichment factor above 3 can be achieved. The detection limit (signal-to-noise ratio = 3) of 35 ng/ml was obtained. RSD at 0.2 mug/ml level was 4.7% (n = 6). The results of dialysis of noble metals mixtures are demonstrated.     

Duality transformations in electrodynamics

Electrodynamics admitting a duality transformation group is considered. For such an electrodynamics an extension of the classical Rainich-Misner-Wheeler theory is presented.On leave of absence from the University of Warsaw, Warsaw, Poland.     

The influence of the local surrounding on the hyperfine interactions in Zr(Fe1−x Ni x )2 compounds

Mössbauer spectroscopy and the TDPAC method have been used to study Zr(Fe_1–x Ni _x )₂ compounds forx0.30. The hyperfine magnetic field at the Fe sites and the quadrupole splitting as functions of nickel concentration were analysed by use of⁵⁷Fe Mössbauer spectroscopy. Values of the internal magnetic field on¹⁸¹Ta nuclei have been found by means of the TDPAC method.     

Critical circle maps near bifurcation

We estimate harmonic scalings in the parameter space of a one-parameter family of critical circle maps. These estimates lead to the conclusion that the Hausdorff dimension of the complement of the frequency-locking set is less than 1 but not less than 1/3. Moreover, the rotation number is a Hölder continuous function of the parameter.Partially supported by KBN grant Iteracje i Fraktale #210909101.Partially supported by NSF Grant #DMS-9206793 and the Sloan Research Fellowship.