Ekeland’s principle for vector equilibrium problems

In this paper, the authors deal with bifunctions defined on complete metric spaces and with values in locally convex spaces ordered by closed convex cones. The aim is to provide a vector version of Ekeland’s theorem related to equilibrium problems. To prove this principle, a weak notion of continuity of a vector-valued function is considered, and some of its properties are presented. Via the vector Ekeland’s principle, existence results for vector equilibria are proved in both compact and noncompact domains.     

Focusing-defocusing phenomena of radio echo signal after passage of the morning solar terminator

Summary Campaign results of high-repetition ionospheric soundings, performed at the ionospheric station of Rome using a Digisonde 128P, are presented. We introduce an index derived from run rapid ionograms that can be used to detect oscillations of isodensity surfaces ofF ionospheric region started by morning solar terminator.     

The behaviour of alkylcobalt carbonyls under “oxo” conditions

Both normal and secondary alkylcobalt carbonyls are shown not to undergo isomerization under catalytic “oxo” conditions, and the relevance of this obervation for the mechanism of the “oxo” reaction is discussed.     

Asymmetric synthesis by chiral ruthenium complexes : VI. Enantiomer-discrimination in the hydrogen transfer from racemic alcohols to prochiral ketones in the presence of H4Ru4(CO)8[(−)-diop]2

Hydrogen transfer from racemic alcohols to prochiral ketones in the presence of H₄Ru₄(CO)₈[(?)-DIOP]₂ has been examined. The enantiomer-discrimination is influenced by the structure of the reactants, temperature and the excess of phosphine present.     

Fractionation of basic nuclear proteins of human sperm by zinc chelate affinity chromatography

Immobilized metal affinity chromatography was investigated for the fractionation of basic nuclear proteins of human sperm. Human sperm nuclei essentially contain two classes of protamines: a protamine of type P1 (HPl), rich in cysteine but with only one histidine, and three protamines of type P2 (HP2, HP3, HP4), rich in cysteine and histidine (nine in protamine HP2), potential ligands for transition metal ions. The critical conditions for metal affinity chromatography were defined: choice of metal, protein material and buffer, type of elution and sample loading. Chromatography of nuclear proteins, without histones and with cysteine residues alkylated by iodoacetamide, was optimum on zinc Chelating Sepharose in a Tris-acetate buffer and elution with an increasing concentration gradient of imidazole. Under these conditions, the two classes of protamines were completely separated. The intermediate basic proteins were further purified by reversed-phase high-performance liquid chromatography. Heterogeneity of binding to zinc of protamine HP1 was demonstrated. The proposed method is simple and reproducible and the recovery of proteins is high. It may be applied to study the expression and function of P1 and P2 protamines, e.g., in the case of infertile men.     

Heats of adsorption of linear CO species adsorbed on the Au degrees and Ti+delta sites of a 1% Au/TiO2 catalyst using in situ FTIR spectroscopy under adsorption equilibrium

The heats of adsorption of two linear CO species adsorbed on the Au degrees particles (denoted L(Au degrees)) and on the Ti(+delta) sites (denoted L(Ti+delta)) of a 1% Au/TiO(2) catalyst are determined as the function of their respective coverage by using the AEIR procedure (adsorption equilibrium infrared spectroscopy) previously developed. Mainly, the evolutions of the IR band area of each adsorbed species (2184 cm(-1) for L(Ti+delta) and at 2110 cm(-1) for L(Au degrees)) as a function of the adsorption temperature T(a), at a constant CO adsorption pressure P(CO), provide the evolutions of the coverages theta(LTi+delta) and theta(LAu degrees ) of each adsorbed CO species with T(a) in isobar conditions that give the individual heats of adsorption. It is shown that they linearly vary from 74 to 47 kJ/mol for L(Au degrees ) and from 50 to 40 kJ/mol for L(Ti+delta) at coverages 0 and 1, respectively. These values are consistent with literature data on model Au particles and TiO(2). In particular, it is shown that the mathematical formalism supporting the AEIR procedure can be applied to literature data on Au-containing solids (single crystals and model particles).     

Synthesis of new tren-based tris-macrocycles. Anion cluster assembling inside the cavity generated by a bowl-shaped receptor

The synthesis of three new tris-macrocycles, containing three [12]aneN(4) (L1), [12]aneN(3)O (L2), or [14]aneN(4) (L3) moieties appended to a tren unit, is reported. The crystal structure of the [(Na(ClO(4))(6)) subset L1(2)H(13)]Na(6)Cl(2)(ClO(4))(12) compound shows the anionic cluster [Na(ClO(4))(6)](5)(-) assembled inside the cavity defined by two bowl-shaped polyammonium receptors, held by multiple charge-charge and hydrogen bond interactions.