Study of ion beam induced mixing in Sn/Si system using electrical resistivity measurements

The ion-beam mixing of Sn thin film evaporated on silicon has been investigated by continuously measuring the electrical resistivity of the sample during irradiation by Kr ions. The resistivity results exhibit a tendency toward a saturation process and allow the determination of the critical dose corresponding to the total mixing condition. The variation of the volume fraction of intermixed atoms as a function of the ion dose has been deduced and compared with a semiempirical formula to explain the observed mixing kinetics. A linear dependence of the volume fraction of the intermixed atoms on the fluence is observed, which is a signature of recoil type mixing.     

Spectrophotometric assay of retinol via charge-transfer complexes

Simple and sensitive spectrophotometric methods for the assay of retinol have been presented. The first method was based on the reaction of retinol with iodine to give a molecular charge-transfer complex, the retinol acting as n-donor and iodine as -electron acceptor. The second method depends on the formation of a highly coloured stable radical anion between retinol and 7,7,8,8-tetracyanoquinodimethane (TCNQ as a -electron acceptor. The molecular ratios of the reactants in the complexes have been established and the experimental conditions leading to maximum charge-transfer bands were also studied. Beer's law is obeyed over the retinol concentration range 2.5–26 µg/ml. The proposed procedures have been applied successfully to the analysis of drug formulation. The average recovery and average standard deviation was 99.99 ±1.13% with retinol-iodine and 100.001 ± 1.31% with retinol-TCNQ. A kinetic study was performed by heating retinol at 50°C for different periods of time, the result obtained by plotting log c against time indicates that thermal decomposition of retinol is of first order. The results obtained by both methods were in good agreement with those obtained by the official method. The developed procedures were found to be simple, accurate and precise and can be used for the determination of retinol in presence of its degradation products.     

Complexes of vitamin B6 XII : Mixed ligand complexes of some divalent metal ions with pyridoxamine and histidine

Potentiometric pH titrations (I = 0.15 M NaNO₃; 37°C) have been employed to study the various complex equlibria in the systems involving pyridoxamine and histidine with Co(II), Ni(II), Cu(II), and Zn(II). The stoichiometry and formation constants of different species have been determined with the aid of MINIQUAD-75. The complexes obtained were mostly protonated and positively charged. The formation of the ternary species is discussed in terms of the binary species. They were also correlated with the quaternary species involving pyridoxamine, glycine, and imidazole. Spectral analysis of the complex solutions of different compositions are also reported. The relevance of these ternary complex equilibria to some biological functions is discussed.     

Ion-beam induced mixing of Cu/Au bilayer thin film (kinematics and formation of solid solutions)

Ion-beam induced atomic mixing of Cu/Au bilayer thin film is studied using combined electrical resistivity measurements and Rutherford Backscattering Spectrometry (RBS). 400 keV Kr⁺ ion irradiation with fluences ranging from 3.3×10¹⁵ to 7.6×10¹⁶ ions/cm² at room temperature have been used. Ion beam mixing lead to a uniformly mixed metal alloy. The formation of Cu/Au solid solutions depends on the initial composition and on the fluence of irradiating ions. For an initial composition of Cu₄₂Au₅₈, a Cu-rich solid solution of composition Cu₇₂Au₂₈ is formed after irradiation with 7.6×10¹⁶ ions/cm². The kinematics of the intermixing process is also studied by in situ electrical resistivity measurements which confirmed the formation of the Cu/Au solid solutions.     

An MCl inf4 p2− moiety (M = copper,zinc, cadmium and mercury) stabilized by bis(ethylenediamine)copper(II) cation

Summary New ionic bimetallic complexes of the type [Cu(en)₂]-[MCl₄], where M = Cu^II, Zn^II, Cd^II and Hg^II, were prepared by reacting bis(ethylenediamine)copper(II) dichloride (1 mol) with copper, zinc, cadmium and mercury dichlorides (1 mol) in absolute alcohol. Elemental analyses, conductivity and magnetic susceptibility measurements, and spectroscopic data (such as i.r., u.v.-vis. and e.p.r.) confirm that the compounds are 22 electrolytes in MeOH and that the copper(II) ion is paramagnetic, maintaining its square-planar geometry, while metal ions in the anionic moiety of the complexes achieve their usual tetrahedral environment. An augmented magnetic moment has been observed in the [Cu(en)₂] [CuCl₄] complex, which is attributed to the ferromagnetic effect and TIP.Author to whom all correspondence should be directed.     

Influence of structure and polarity of polysiloxanes on retention of N-TFA butyl esters of amino acids

In this work, we have investigated the influence of the polarities and structures of 13 polysiloxanes on the retention of some N-TFA N-butyl esters of amino acids. Gehrke [1] was the first to examine the possible relationship between polarity and retention data of amino acid derivatives for 9 stationary liquid phases. He concluded that the molecular structure of the stationary liquid phase is an important factor determining retention.     

Radiation Polymerization of 4-(Acryloylamido)benzonitrile: Zinc and Copper Complexes

Summary. The new polymer containing cyano groups was synthesized by γ-irradiation. The oximated polymer was prepared using hydroxylamine hydrochloride in basic medium. The characterization of monomer, polymer, and oximated ones was confirmed by infrared and nuclear magnetic resonance spectroscopy. The complex formation of the amidoxime salt towards Zn^II, Cu^II, and Zn^II/Cu^II mixture in aqueous solution was studied by atomic absorption spectroscopy, energy dispersive spectroscopy, and electron spin resonance spectrometry. The significant binding capacity of these metal ions revealed its selectivity to Zinc(II) ion. The thermal stability of polymers and complexed ones was investigated using thermogravimetry analysis. The change in their morphology was observed by scanning electron microscopy (SEM).