Interaction of a vinyl acetate—vinyl chloride based wetting binder with metal particles for magnetic recording

The interaction of two commercially available iron alloy particles with a wetting binder based on a vinyl chloride and vinyl acetate copolymer has been investigated. The interaction was studied using the techniques of flow microcalorimetry, X-ray photoelectron spectroscopy (XPS) and microelectrophoresis. The results obtained indicate that whereas both particles interact strongly with the wetting binder, particles of low nickel content are characterized by very high heats of interaction (about 37–47 kcal mol⁻¹). The adsorption on both particles appears to obey the Freundlich equation. Binder adsorption on particles results in the development of rather large zeta potentials in tetrahydrofuran solutions. XPS experiments are unable to provide any conclusive evidence for the interaction mechanism.     

Electron impact ionization of amines using crossed electron-molecular beams

Ionization energy functions of triethyl amine, tri-n-propyl amine, N,N-dimethyl-benzenamine and N,N-diethyl-benzenamine, and appearance energy functions of major products of dissociative ionization have been measured using a high sensitivity crossed electron beam-molecular beam apparatus incorporating a quadrupole mass spectrometer and an on-line laboratory computer. The data obtained is useful in understanding the role of dopants in gas laser plasmas.     

Preparation and certification of high-grade gold geochemical reference material

One high-grade gold geochemical reference material-BND 3401.01 has been prepared by the National Geophysical Research Institute (NGRI), Hyderabad in collaboration with the Hutti Gold Mines Company Limited (HGML), Hutti and National Physical Laboratory (NPL), New Delhi, in India. The sample is a sheared gold-sulphide-bearing quartz vein emplaced in a sheared acid volcanic rock that was collected at the 2400-foot level from the middle reef of Hutti deposit located in the north-western periphery of the late-Archaean Hutti-Maski greenstone belt, Karnataka, India. Fifteen institutions in India, Canada, China and Tanzania having experience in geochemical analysis had participated in this collaborative analysis programme. The sample was extensively characterized for its major, minor, trace and ultra-trace element composition by using a variety of analytical techniques. Usable values were provided for major, minor and several trace elements including all rare earth elements (REE). The certified value for the gold concentration in BND 3401.01 gold ore is 12.1±0.7 mg/kg.     

Mixed-ligand chelate extraction of trivalent lanthanides and actinides with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 and dihexyl-N,N-diethylcarbamoylmethyl phosphonate

Mixed-ligand chelate extraction of trivalent lanthanides such as La, Eu and Lu and a trivalent actinide, Am into xylene with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and dihexyl-N,N-diethylcarbamoylmethylphosphonate (CMP) has been studied by tracertechniques. These trivalent metal ions are found to be extracted from 0.01 mol/dm³ chloroacetate buffer solutions as M(PMBP)₃·HPMBP type self adducts with HPMBP alone and in the presence of CMP as M(PMBP)₃·CMP (where M=La, Eu, Lu and Am) into the organic phase. The equilibrium constants of the above species are deduced by non-linear regression analysis. The synergistic constants of trivalent lanthanides do not increase monotonically with atomic number but have a maximum at Eu and that of Am was found to lie between that of La and Eu.     

Two-photon ionization of Li2: isotopic separation and determination of IP(Li2) and De(Li+2)

Complete isotope separation is achieved by two-photon ionization of Li₂ by a single mode Ar⁺ laser. With the use of two Ar⁺ lasers, the ionization potential of Li₂ is found to be 5.174 ± 0.013 eV, and the dissociation energy D_e(Li⁺₂) to be 1.274 ± 0.019 eV.     

Thermodynamics of thiocyanate complexes of trivalent actinides and lanthanides

The thermodynamic parameters ΔF, ΔH and ΔS of the complexes of Cm(III), C(III) and Tm(III) with the SCN^? ion have been determined at 30°C in ammonium ion medium of unit ionic strength by the temperature variation method. It has been concluded that both the thiocyanate complexes of trivalent actinides and lanthanides are predominantly inner-sphere type. The higher stability of the second complexes of trivalent actinides is reflected either in the enthalpy or the entropy change depending on the degree of hydration of the trivalent actinide ions. The implications of the greater free energy change for PuSCN²⁺ as compared with other trivalent actinide or lanthanide first thiocyanate complexes are discussed.     

Sorption of Am(III), U(VI) and Cs(I) on sodium potassium fluorophlogopite, an analogue of the fluorine mica mineral

The sorption of ²⁴¹Am, ²³³U and ¹³⁷Cs from nitric acid solutions on a synthesized sodium potassium fluoro-phlogopite (SPFP) gel, structurally close to the fluorine mica mineral, has been studied. The synthesized gel was characterized by energy dispersive spectrometry, X-ray powder diffraction pattern, FTIR and thermogravimetric analysis and has a composition of Na_0.5K_0.5Mg₃(Si₃AlO₁₀)F₂.6H₂O. Different parameters like contact time, acid concentration, amount of SPFP, metal ion concentrations, effect of competing cations, desorption of the nuclides from the loaded SPFP gel etc., were studied using batch technique. Also, the SPFP gel was loaded with Eu(III), U(VI) and Cs(I) and the amounts sorbed on the gel has been estimated by difference from the concentrations in the original solution and those remaining in the solution after loading. Na, K, Mg, Eu and U were estimated by ICP-AES and Cs by electrothermal atomization atomic absorption spectrometry. The exchange of Na, K and Mg with the loaded cations has been evaluated and discussed in the light of ion exchange and surface precipitate sorption mechanisms.     

Liquid membrane phenomena and drug action

A wide variety of drugs are known to ber surface active and in a number of cases excellent correlations between surface activity and biological effects have been demonstrated. This fact indicates the possibility of a common mode of action for all surface active drugs. Literature reports on the surface activity of drugs indicating such a possibility are reviewed. Recent investigation on structurally dissimilar drugs of different pharmacological categories have revealed that the liquid membranes which are likely to be generated by the surface active drugs at the respective sites of action may act as a barrier to the transport of relevant permeants. The formation of such liquid membranes migh be an important step common to the mechanism of action of all surface active drugs. A consolidated account of all such investigations is presented.This concept that liquid membrane barriers generated by the drug itself modify access of the relevant permeants to the receptor site has been discussed in the light of existing theories of drug action, particularly the occupancy theory and the rate theory. As a result of this discussion, a more rational biophysical explanation for the action of such drugs which act by modifying the permeability of cell membranes has emerged.     

“Broken-hearted” carbon bowl via electron shuttle reaction: energetics and electron coupling

Unprecedented one-step C C bond cleavage leading to opening of the buckybowl (π-bowl), that could provide access to carbon-rich structures with previously inaccessible topologies, is reported; highlighting the possibility to implement drastically different synthetic routes to π-bowls in contrast to conventional ones applied for polycyclic aromatic hydrocarbons. Through theoretical modeling, we evaluated the mechanistic pathways feasible for π-bowl planarization and factors that could affect such a transformation including strain and released energies. Through employment of Marcus theory, optical spectroscopy, and crystallographic analysis, we estimated the possibility of charge transfer and electron coupling between “open” corannulene and a strong electron acceptor such as 7,7,8,8-tetracyanoquinodimethane. Alternative to a one-pot solid-state corannulene “unzipping” route, we reported a nine-step solution-based approach for preparation of novel planar “open” corannulene-based derivatives in which electronic structures and photophysical profiles were estimated through the energies and isosurfaces of the frontier natural transition orbitals.

An electron shuttle contributed to breaking corannulene''s heart through a unique one-step reductive C C bond cleavage in the traditionally robust π-bowl. The heartbreak did not stop there as “broken analogs” were developed through a solution-phase route.