On a new partitioning of the Hamiltonian in many-body calculation of pair-correlation energies in closed-shell systems

We introduce here a new partitioning of the Hamiltonian in calculating pair-correlation energies using many-body perturbation theory, by which we are able to eliminate the off-diagonal particle–hole (p–h) ladders exactly to all orders in the perturbation expansion. In this formulation, the particle states turn out to be different for each distinct pair of hole states in the correlation energy calculation. We have also included the contributions of the diagonal particle–particle (p–p) and hole–hole ladders exactly to all orders. The effect of the off-diagonal p–p ladders has been estimated for each pair by computing the third-, foruth- and fifth-order energies. For highly symmetric systems the present partitioning yields in general symmetry-broken orbitals. Here one may use an average kind of partitioning for all the partners of the degenerate sets, which restores the symmetry and at the same time ensures cancellation of the p–h ladders exactly at the lowest order and approximately at the higher orders. Results are presented for a selection of 6π-electron conjugated systems. The correlation energy for each pair is in excellent agreement with that obtained from a partial CI calculation involving all double excitations from this pair. The advantages of implementing the present scheme in larger systems has been discussed.     

Removal of actinides and fission products activity from intermediate alkaline waste using inorganic exchangers

Hydrated iron oxide or amorphous-Fe₂O₃·3.5 H₂O (HFeO), hydrated titanium oxide (HTiO) and hydrated thorium oxide (HThO) were synthesized and their applicability for the decontamination of intermediate level liquid wastes (ILLW) was tested. The sorption of a few actinides like plutonium and americium on HFeO, ¹³⁷Cs and ¹⁰⁶Ru on HTiO and ⁹⁰Sr on HThO was investigated as a function of pH, time and loading capacity of the hydrous oxide with metal ions. The influence of the total dissolved salt content was also monitored. Some of these parameters influenced the sorption behavior significantly. The radiation stability of these inorganic sorbents were studied by irradiating them up to 48 Mrad. Adsorbed actinides and fission products were successfully eluted from HFeO and from the mix-bed of HTiO and HThO by 0.5M nitric acid.The authors wish to thank Shri R. D. Changarani, Chief Superintendent NRG Facilities and Shri P. K. Dey, Head FRD for their valuable advice and constant support.     

Micropolar flow past a stretching sheet

Summary This paper studies the flow of an incompressible, constant density micropolar fluid past a stretching sheet. The governing boundary layer equations of the flow are solved numerically using a globally convergent homotopy method in conjunction with a least change secant update quasi-Newton algorithm. The flow pattern depends on three non-dimensional parameters. Some interesting results are illustrated graphically and discussed.

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Résumé Nous étudions l'écoulement d'un fluid micropolaire et incompressible, de densité constante, le long d'une surface qui l'étend. Les équations de la couche limite qui régissent l'écoulement sont résolues numériquement. On utilise un algorithme quasi-Newtonien de type least change secant update avec une méthode homotopique /`a convergence globale. Certains résultats intéressants sont discutés et illustrés graphiquement.

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This work performed at Sandia National Laboratories supported by the U. S. Department of Energy under contract number DE-AC04-76DP00789.     

Studies on the colloidal properties of papain with titanium dioxide sol

Summary The coagulation concentration for a titania sol decreases if the concentration of a mixture of electrolytes and papain decreases. If the concentration of papain is increased then lesser amount of electrolytes is needed to coagulate the sol. If glycine is added as an additional substance then the value decreases more rapidly. There is no significant change in the p_H and the electrical conductance of the sol by the addition of papain or electrolytes. There is a little change, when glycine is added as an additional substance. These observations are explained due to the formation of negative papain ions in a low p_H region. The possibility of the adsorption or the release of the counter ions is ruled out.The authors wish to thank Dr.R. C. Mehrotra, Professor and the Head of the Chemistry Department for providing all the facilities for this work. We are also thankful to the Ministry of Education, Government of India, for the award of a research scholarship to one of us (V.K.S.).     

Methods for the preparation of mercury and osmium samples suitable for ion microprobe measurements

Using radiotracer solutions of Hg (²⁰³Hg) and Os (¹⁸⁵Os), techniques have been developed for sampling these elements presumably suitable for ion probe measurements. Mercury has been electrodeposited on the cross-sectional area (5 mm²) of an electrochemically pure Cu wire giving a recovery 25 to 30% at the tip. Similar efficiency is found for Hg distillate solutions. Osmium has been collected in a Ni–NiS bead after loading its thiourea complex solution on filter paper. The recovery in the bead is 80–90%. These methods should be of help for isotopic study of these elements by ion microprobe. The suitability of these samples for measurements remains unconfirmed.     

Spectrophotometric studies on the zirconium complex of 2-(3,6-disulfo-8-hydroxynaphthylazo)-1,8-dihydroxynaphtualene-3, 6-disulfonic acid

Summary A chromotropic azo dye, DSNADNS, prepared from chromotropic acid and 1-amino-8-naphthol-3,6-disulfonic acid has been found to produce quantitative precipitation of zirconium in acid medium. The blue-violet complex formed is insoluble in all organic solvents commonly used for solvent extraction work, but is soluble in a number of liquid organic bases and solutions of ammonium salts in water showing pink to violet colouration. Spectrophotometric studies as to the nature of the complex in pyridine, triethanolamine ammonium acetate, oxalate and carbonate solutions and the analytical possibility of these solutions have been made. The complex appears to decompose in pyridine, ammonium acetate and ammonium oxalate solutions, but it is fairly stable in ammonium carbonate and triethanolamine solutions. The absorbance peaks of the dye in these solutions occur at 500 and 520 nm respectively, while the complex in triethanolamine and ammonium carbonate both shows absorbance maxima at 540 nm. The solution of the complex in these two solvents obeys Beer's law within a concentration range 4 to 25 mg of zirconium per litre. The molar absorbance coefficients of the complex in triethanolamine and ammonium carbonate are respectively 686 and 823, which indicate poor sensitivity. The solution of the complex in the former solvent is more stable than that in the latter and an analytical procedure for the spectrophotometric determination of zirconium, with little interference from foreign ions, may be developed with ease in the triethanolamine solution.

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Zusammenfassung Ein Azofarbstoff der Chromotropsäure, DSNADNS, der aus Chromotropsäure und 1-Amino-8-naphthol-3,6-disulfonsäure dargestellt werden kann, ergibt mit Zirkonium in saurer Lösung eine quantitative Fällung. Der blauviolett gefärbte Komplex ist in allen üblichen organischen Lösungsmitteln unlöslich, löst sich jedoch in einigen flüssigen organischen Basen sowie wäßrigen Lösungen von Ammoniumsalzen mit rosa bis violetter Färbung. Die Lösungen des Komplexes in Pyridin, Triäthanolamin sowie in Ammoniumacetat, -oxalat und -carbonatlösungen und ihre analytische Verwendbarkeit werden spektrophotometrisch untersucht. In Pyridin sowie in Ammoniumacetat und -oxalatlösungen scheint sich der Komplex zu zersetzen, während er in Triäthanolamin und Ammoniumcarbonatlösungen ziemlich beständig ist. Das Absorptionsmaximum des Farbstoffs in diesen beiden Lösungsmitteln liegt bei 500 bzw. 520 nm, der Komplex weist in beiden Fällen ein Maximum bei 540 nm auf. Das Beersche Gesetz wird in beiden Lösungsmitteln von 4–25 mg Zr/l erfüllt. Der molare Absorptionskoeffizient beträgt 686 bzw. 823. Die Lösung des Komplexes in Triäthanolamin ist stabiler als in Ammoniumcarbonatlösung. Eine spektrophotometrische Bestimmung von Zirkonium, die nur wenig von Fremdionen gestört wird, könnte daher gut in Triäthanolaminlösung durchgeführt werden.

     

Synthesis, X-ray structure and properties of a new nitrite-bound copper(II) complex with 2-(3,5- dimethylpyrazol-1-ylmethyl)pyridine in a CuN4(O) coordination

Synthesis and characterization of a nitrite-bound copper(II) compound [CuL⁴)₂(ONO)]ClO₄ have been achieved (L⁴ = 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine]. The bidentate ligand L⁴ provides a pyridine and a pyrazole donor site; however, they are separated by a methylene spacer. The complex has been structurally characterized and it belongs to only a handful of complexes having nitrito-bound mononuclear copper(II) centre. The metal atom has a distorted square pyramidal geometry with the copper atom displaced from the equatorial plane by 0.25 Å. In MeCN solution the green complex exhibits a broad ligand-field transition at 655 nm with a shoulder at 675 nm and in dichloromethane-toluene glass (80 K) it exhibits an EPR spectral feature characteristic of the unpaired electron in the d_x²−y² orbital. Variable-temperature (80–300 K) magnetic susceptibility measurements in the solid state as well as room temperature measurement in MeCN solution reveal mononuclear magnetically dilute copper(II) centre. When examined by cyclic voltammetry (MeCN solution) it displays electrochemically irreversible Cu^II---Cu^I response [cathodic peak potential, E_pc (V vs saturated calomel electrode (SCE)): −0.32]. An oxidative response is observed at 1.14 V, probably due to bound-nitrite oxidation and is partially removed to generate a solvated complex at the electrode surface. The latter species gives rise to reversible Cu^II---Cu^I redox response [ ].     

Palladium salicylaldimine complexes containing boronate esters

Reactions of salicylaldehydes with boronate ester derivatives of aniline have been examined. Addition of these Schiff base ligands to palladium acetate or Na₂PdCl₄ afforded novel boron-containing trans-bis(N-arylsalicylaldiminato) palladium complexes.Condensation of salicylaldehyde (2-HOC₆H₄C(O)H) with H₂NC₆H₄Bpin (pin=1,2-O₂C₂Me₄) afforded the boron-containing Schiff bases, 2-HOC₆H₄C(H)=NC₆H₄Bpin (1–3a). Similar reactivity with 2-hydroxy-5-nitrobenzaldehyde and 2-hydroxy-1-naphthaldehyde gave the corresponding Schiff bases (1-3b) and (1-3c), respectively. Reaction of Schiff bases (2) and (3) with palladium acetate or Na₂PdCl₄ afforded complexes of the type PdL₂ (4,5), where L=deprotonated Schiff base. The molecular structure of the nitro-salicylaldehyde 4-Bpin palladium complex (5b) was characterized by an X-ray diffraction study. All new palladium compounds have been characterized fully and tested for their antifungal activity against Aspergillus niger and Aspergillus flavus.     

Stability of AQUO-organic silver iodide sol

Summary The coagulation concentration for silver iodide sol, both in presence of pyridine and dioxane, increases for mono- and bivalent coagulating electrolyte. In presence of a mixture of pyridine and dioxane in equal volume, the coagulation concentration assumes an intermediate value, which is nearer to dioxane. However, in presence of dioxane more bivalent electrolyte is needed than in presence of pyridine. If a bivalent coagulating electrolyte is added to a sol containing a mixture of pyridine and dioxane, the amount of electrolyte required to coagulate is less than pyridine and greater than dioxane. Thus silver iodide sol is more stable toward mono- and bivalent coagulating electrolytes. The degree of stabilization increases with the decrease of the dielectric constant of the dispersing medium. The intermediate values for dioxane pyridine mixture is accountable by the fact that dioxane acts as a solvent for pyridine. The PH value of the sol increases up to the coagulation point. Beyond this, there is an abrupt decrease. When the particles settle down completely a rise in PH is again noted on the further addition of electrolytes. The increase in the electrical conductance is more significant after coagulation. These changes have been explained by adsorption of the ions and due to the release of ions from the electrical double layer.

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Zusammenfassung Die Koagulationskonzentration für Silberjodidsol in Gegenwart von Pyridin und Dioxan steigt für ein- und zweiwertige Elektrolyte an. In Gegenwart einer Mischung zu gleichen Volumen erh?lt man mittlere Werte, n?her denen zu Dioxan. Für Koagulation in Gegenwart von Dioxan ist jedoch mehr zweiwertiger Elektrolyt notwendig als in Gegenwart von Pyridin. Bei Koagulation mit zweiwertigem Elektrolyt verbraucht ein Sol mit der Mischung von Pyridin und Dioxan weniger als für Pyridin und mehr als für Dioxan. Daher ist das Silbersol gegenüber ein- und zweiwertigen Elektrolyten stabiler. Der Grad der Stabilisierung w?chst mit abnehmender Dielektrizit?tskonstante des Dispersionsmediums. Die Zwischenwerte der Dioxan-Pyridin-Mischungen lassen sich verstehen durch die Tatsache, da? Dioxan als L?sungsmittel für Pyridin wirkt. Der PH-Wert des Sols w?chst bis zum Koagulationspunkt, darüberhinaus erfolgt ein steiler Abfall. Wenn die Teilchen vollst?ndig absetzen, ist bei weiterer Zugabe von Elektrolyt ein erneuter Anstieg im PH feststellbar. Der Anstieg der elektrolytischen Leitf?higkeit wird nach der Koagulation ausgepr?gter. Diese ?nderungen lassen sich durch Ionenadsorption und Freiwerden von Ionen aus der elektrischen Doppelschicht erkl?ren.

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Our thanks are due to Prof. R. C. Mehrotra for providing all the facilities for this work and to Prof. S. Ghosh of Allahabad University for helpful discussions. Thanks are also due to the University Grants Commission, Government of India, for the award of a research scholarship to one of us (V. K. S.).     

Rapid separation of phenylthiohydantoin amino acids: ambient pressure ion-mobility mass spectrometry (IMMS)

An electrospray ionization (ESI) ambient pressure ion-mobility spectrometer (APIMS) interfaced to an orthogonal reflector time-of-flight mass spectrometer (TOFMS) was evaluated for the first time as a detector for the identification of phenylthiohydantoin (PTH)-derivatized amino acids, the final products in the Edman sequencing process of peptides and proteins. The drift and flight times of the twenty common PTH amino acids were characterized by a well-defined 2-D mobility/mass spectral pattern. The combination of mobility/mass modes of analysis gave rise to a unique trend-line formation for the series of PTH amino acids. In addition, each PTH amino acid had a unique reduced mobility constant K(o), thus enabling the differentiation of all the amino acid derivatives including the PTH-leucine and PTH-isoleucine isomers. More importantly it was shown that it was possible to resolve a complete reference mixture of PTH amino acids in a single experimental run in less than 1 min. Detection limits for the PTH amino acids were found to range from 1.04 to 3.52 ng; indicating that the limits of detection were less than 17.0 pmol for all of the PTH amino acids.