Selective extraction of iron(III) from aqueous nitrate solution in the presence of cobalt(II), copper(II) and nickel(II) ions using bis(delta2-2-imidazolinyl)-5,5'-dioxime.

The feasibility of using bis(delta2-2-imidazolinyl)-5,5'-dioxime (H2L) for the selective extraction of iron(III) from aqueous solutions was investigated by employing an solvent-extraction technique. The extraction of iron(III) from an aqueous nitrate solution in the presence of metal ions, such as cobalt(II), copper(II) and nickel(II), was carried out using H2L in binary and multicomponent mixtures. Iron(III) extraction has been studied as a function of the pH, equilibrium time and extractant concentration. From the extracted complex species in the organic phase, iron(III) was stripped with 2 M HNO3, and later determined using atomic-absorption spectrometry. The extraction was found to significantly depend on the aqueous solution pH. The extraction of iron(III) with H2L increases with the pH value, reaching a maximum in the zone of pH 2.0, remaining constant between 2 and 3.5 and subsequently decreasing. The quantitative extraction of iron(III) with 5 x 10(-30 M H2L in toluene is observed at pH 2.0. H2L was found to react with iron(III) to form ligand complex having a composition of 1:2 (Fe:H2L).     

Erratum: Synthesis and characterization of diorganotin(IV) complexes of Schiff bases with ONO‐type donors and crystal structure of [N‐(2‐hydroxy‐4‐nitrophenyl)‐3‐ethoxysalicylideneiminato]diphenyltin(IV)

The article referenced above was first published online on 30 August 2007 with incorrect pagination; the pagination has now been corrected online and in print. Copyright © 2007 John Wiley & Sons, Ltd.     

Metallophthalocyanines with rod-shaped substituents

4-(4′-Dioctylaminocarbonylbiphenyloxy) phthalonitrile was synthesized from 4-(4′-carboxybiphenyloxy)phthalonitrile and dioctylamine in the presence of Et₃N. Metallophthalocyanines (Zn, Co and Cu) substituted with four dioctylaminocarbonyl biphenyloxy groups on the peripheral positions were prepared from 4-(4′-dioctylaminocarbonylbiphenyloxy)phthalonitrile and the corresponding divalent metal salts (Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The new phthalocyanines are soluble in common organic solvents. These compounds were characterised by ¹H-NMR, ¹³C-NMR, FT-IR, UV-Vis and mass spectroscopies.     

Immobilization of α-amylase in vinyl-polymer-based interpenetrating polymer networks

Semi-interpenetrating polymer networks (IPNs) of poly(ethylene glycol), poly(vinyl alcohol) and polyacrylamide were prepared as a support for enzyme immobilization and kinetic studies were performed for the immobilization of -amylase. The effect of IPN composition on the extent of immobilization was investigated and the percentage of relative activity of the immobilized enzyme was evaluated as a function of the chemical architecture of the IPNs, pH and temperature, taking starch as a substrate. The kinetic constants and the maximum reaction velocity were also evaluated. The IPNs were characterized by IR spectral analysis.     

New instanton and meron solutions of a generally covariant four-dimensional sigma model

We construct new solutions of the fourdimensional sigma model coupled to the metric tensor field and having an internalO invariance. Our solutions interpolate continuously between the known instanton and meron solutions depending upon a parameterf. We find that the typical domain for the instantons is 2<f≦3 while for the merons is 0≦f≦2.     

Zwitterionic ion chromatography with carboxybetaine surfactant-coated particle packed and monolithic type columns

Both particle packed (25 cm x 0.46 cm I.D. SUPELCOSIL 5 microm C18) and monolithic type (10 cm x 0.46 cm I.D. Merck Chromolith Performance C18) reversed-phase substrates were dynamically coated with a carboxybetaine type zwitterionic surfactant ((dodecyldimethyl-amino) acetic acid) and investigated as stationary phases for use in zwitterionic ion chromatography (ZIC). Investigations into eluent concentration and pH were carried out using KCl eluents containing 0.2 mM of the carboxybetaine surfactant to stabilise the column coatings. It was found that eluent concentration decreased anion retention whilst simultaneously increasing peak efficiencies, which may be due to the dissociation of intra- and inter-molecular salts of the carboxybetaine surfactant under higher ionic strength conditions. The Effect of eluent pH was an increase in anion retention with decreased eluent pH due to the increased protonation of the weak acid terminal group of the carboxybetaine, causing both a relative increase in the positive charge of the stationary phase and less repulsion of the anions by the dissociated weak acid group. The carboxybetaine-coated monolithic phase was applied to rapid anion separations using elevated flow rates and flow rate gradients.     

Radiation effect studies in single crystal of Trifluoroacetyl-α-Aminoisobutyric acid

In this study, electron paramagnetic resonance of γ-irradiated single crystals of N-Trifluoroacetyl-α-amino isobutyric acid (F₃Ac-Aib-OH) was investigated at room temperature and analyzed for different orientations of the crystal in the magnetic field. The paramagnetic species in N-Trifluoroacetyl-α-aminoisobutyric acid was attributed to the ?F₂-R radical (R= CONHC(CH₃)COOH). Hyperfine coupling constants and g value were also determined. In addition, the single crystal of F₃Ac-Aib-OH was UV-irradiated and paramagnetic species formed was studied at room temperature. The effects of gamma irradiation on fluoroamino acid and stability were discussed.     

CPT symmetry in honeycomb lattices and quantum brachistochrone problem

In this paper, we have provided a matrix Hamiltonian model for honeycomb lattices and subsequently obtained the dispersion relation. Furthermore, we have constructed the C operator for the given non-Hermitian Hamiltonian model. The quadratic surfaces are sketched and the quantum Brachistochrone problem is discussed for the given honeycomb lattice model.