Strangeness nuclear physics: a critical review on selected topics

Selected topics in strangeness nuclear physics are critically reviewed. This includes production, structure and weak decay of $\Lambda$--Hypernuclei, the $\bar K$ nuclear interaction and the possible existence of $\bar K$ bound states in nuclei. Perspectives for future studies on these issues are also outlined.Comment: 63 pages, 51 figures, accepted for publication on European Physical Journal

Comprehensive study of the enzymatic catalysis of the electrochemical oxygen reduction reaction (ORR) by immobilized copper efflux oxidase (CueO) from Escherichia coli

In recent years, enzymatic fuel cells have experienced a great development promoted by the availability of novel biological techniques that allow the access to a large number of enzymatic catalysts. One of the most important aspects in this area is the development of biocatalysts for the oxygen reduction reaction (ORR). Laccases from the group of enzymes called blue multi-cooper oxidases have received considerable attention because of their ability to catalyze the electrochemical oxygen reduction reaction to water when immobilized on metallic or carbonaceous electrode materials. In this paper we report a comprehensive study of the electrocatalytic activity of the enzyme Copper efflux oxidase (CueO) from Escherichia coli immobilized on different electrode materials. The influence of the electrode substrate employed for protein immobilization was evaluated using glassy carbon, gold or platinum electrodes. Gold and platinum electrodes were modified using different self-assembled monolayers (SAM) able to tune the electrostatic interaction between the protein and the substrate, depending on the nature of the terminal functional group in the SAM. The effects of protein immobilization time, electrode potential, solution pH and temperature, protein and O2 concentration have been carefully investigated. Finally, direct electron transfer (DET) was investigated in the presence of the following inhibitors: fluoride (F−), chloride (Cl−) and azide (N−3).Ministerio de Economía, Industria y Competitividad (MINECO)University of AlicanteDepto. de Bioquímica y Biología MolecularFac. de Ciencias BiológicasTRUEpu

An Oxide-Centered Trinuclear Manganese(III) Compound with a Bulky Phenol-Pyrazolate Ligand

A new oxide-centered trinuclear manganese(III) compound with the formula [Mn3(μ3-O)(naphpz)3(O2CMe)(MeOH)2]n (1) {H2naphpz = 2-[1H-pyrazol-5(3)-yl]naphthalen-1-ol} has been synthesized and characterized. Three bulky doubly deprotonated phenol-pyrazole ligands are coordinated to the three manganese(III) ions with a μ3-oxide bridge in the same plane. Methanol and acetate ligands are at the apical positions of the manganese(III) ions. The trinuclear units are bridged by acetate ligands in the anti-anti mode, leading to the formation of 1-D chains. Temperature-dependent magnetic susceptibility studies indicate the presence of overall antiferromagnetic interactions with magnetic exchange constants of J1 ≈ –1.9 and J2 ≈ –5.5 cm–1 and g = 1.91. Weak antiferromagnetic interactions (zJ′ = –0.37 cm–1) between the trinuclear units in the 1-D chain (and between the chains) in compound 1 are present.This work was financially supported by the EC-RTN “QuEMolNa” (No. MRTN-CT-2003-504880) and the ECNetwork of Excellence “MAGMANet” (No. 515767-2).Peer Reviewe

Cyanide-bridged coordination polymers constructed from lanthanide ions and octacyanometallate building-blocks

A new series of cyanide-bridged assemblies, {KH[Ln2(2,3-pzdc)2(CH3OH)(H2O)7][M(CN)8]}·5H2O (Ln3+ = Nd, Gd, Tb, and Dy; M4+ = Mo and W), were synthesised by self-assembling lanthanide ions and octacyanometallate ions in the presence of pyrazine-2,3-dicarboxylic acid (2,3-H2pzdc). These compounds have a 3D structure in which octagon-like Ln4M4(CN)8 rings are connected through a second Ln3+ center via the carboxylate groups of one 2,3-pzdc. The resulting 1D channels are filled with K+ ions and lattice water molecules. The temperature and field dependent magnetization studies as well as ab initio calculations indicate weak ferromagnetic interactions between the Gd3+ ions within the GdMo compound whilst no magnetic interactions exist in GdW analogues. The magnetic properties of Nd3+, Tb3+ and Dy3+ compounds are strongly dominated by the magnetic anisotropy of the lanthanide ions, irrespective of the octacyanometallate building-block used

A dinuclear manganese(III) and a rare pentanuclear manganese(III) compound with a phenol-pyrazole ligand

Reacting Mn(ClO4)2·6H2O and H2phpzEt (H2phpzEt = 5(3)-(2-hydroxyphenyl)-3(5)-ethylpyrazole) in methanol in the presence of sodium hydroxide yields the compound [Mn2(HphpzEt)4(H2O)2](ClO4)2 (1). The pentanuclear [Mn5(μ3-O)2(HphpzEt)3(phpzEt)3(OCH3)(HOCH3)2(O2CPh)] (2) is obtained when performing a similar reaction with Mn(O2CPh)2·2H2O. Compound 1 consists of a symmetric dinuclear manganese(III) cationic unit, [Mn2(HphpzEt)4(H2O)2]2+ with two non-coordinated perchlorate anions. Compound 2 is a rare pentanuclear complex containing all the manganese ions in the oxidation state III and it also has μ3-oxido ligands. Temperature- and field-dependent magnetization studies indicate dominant antiferromagnetic interactions between the manganese(III) ions in both compounds