Schiff base tantalum(V) complexes

Summary Complexes of pentachlorotantalum with the Schiff bases: bis(vanillin)benzidine, bis(vanillin)-o-dianisidine, bis(acetylacetone)benzidine, bis(p-dimethylaminobenzaldehyde)-o-dianisidine, bis(anisaldehyde)-1, 3-propanediamine and bis(p-dimethylaminobenzaldehyde)-o-phenylenediamine have been prepared and characterized by molar conductance, decomposition temperature, elemental and t.g. analyses and i.r. spectral measurements. The conductances reveal that pentachlorotantalum (1 mole) interacts with all the ligands (1 mole), all five chloride ions thus forming simple adducts. A comparative study of the i.r. spectra of the parent ligands and their complexes allows the coordination sites to be ascertained. The studies show that tantalum(V) chloride prefers to form complexes of high coordination number.     

The Dvoretzky-Wald-Wolfowitz theorem and purification in atomless finite-action games

In 1951, Dvoretzky, Wald and Wolfowitz (henceforth DWW) showed that corresponding to any mixed strategy into a finite action space, there exists a pure-strategy with an identical integral with respect to a finite set of atomless measures. DWW used their theorem for purification: the elimination of randomness in statistical decision procedures and in zero-sum two-person games. In this short essay, we apply a consequence of their theorem to a finite-action setting of finite games with incomplete and private information, as well as to that of large games. In addition to simplified proofs and conceptual clarifications, the unification of results offered here re-emphasizes the close connection between statistical decision theory and the theory of games.A first draft of this paper was completed when Khan and Rath were visiting the Institute for Mathematical Sciences at the National University of Singapore in August 2003; they thank the Institute for supporting their visit. A preliminary version was presented at the Midwest Economic Theory Conference held at Indiana University, Bloomington in October 2003; the authors are grateful to Eric Balder, Robert Becker, William Thomson and Myrna Wooders for questions and helpful suggestions.     

A risk based performance evaluation of plate-and-frame heat exchangers

Plate-and-frame heat exchangers (PHEs) operating in process industries are fouled to a greater or lesser extent depending on surface temperature, surface condition, material of construction, fluid velocity, flow geometry and fluid composition. This fouling phenomenon is time-dependent and will result in a decrease in the overall heat transfer coefficient and increase in the pressure drop of the PHE. Once the overall heat transfer coefficient decreases to a minimum acceptable level, cleaning of the equipment becomes necessary to restore the performance. In this paper, we present a simple probabilistic approach to characterize various fouling models that are commonly encountered in many industries. These random fouling growth models are then used to investigate the impact on risk based thermal effectiveness, overall heat transfer coefficient and the hot- and cold-fluid outlet temperatures of a PHE. All the results are presented in a generalized form in order to demonstrate the generality of the risk-based procedure discussed in this paper.     

Kinetic evidence for the occurrence of trianionic tetrahedral intermediate in the hydroxide ion-catalyzed cleavage of 1, 2-benzisothiazolin-3-one-1, 1-dioxide (saccharin)

The kinetics of hydrolytic cleavage of saccharin has been studied at 60°C within the [ōH] range of 0.1 to 3.0 M. The observed pseudo first-order rate constants, k_obs, follow an empirical relationship: k_obs = B[ōH] + [C[ōH]]². The B and C terms are attributed to the formation of dianionic and trianionic tetrahedral intermediates on the reaction path. It is concluded that the ionized form of saccharin is the major reacting species under the present experimental conditions. The positive ionic strength effect and the negative effect of 1,4-dioxan on the rate of hydrolysis favor the proposed reaction mechanism. The analysis of the observed activation parameters indicates that the increase in the contribution of C term to k_obs causes the slight increase in both ΔH* and ΔS*. A significantly large negative value of ΔS* favors the proposed mechanism.     

Semi-empirical formulae for Λ-binding energy in hypernuclei using mass distribution

Semi-empirical formulae for ground state Λ-binding energy of heavy hypernuclei, in inverse powers of the mass number, using the mass distribution in the folding model, under fairly reasonable assumptions about the range of the Λ-nucleon force are obtained in more than one plausible way. However, they are found to give nearly identical results. A reasonable estimate of the Λ well-depth is obtained from a chi-square fit of the available ground state Λ-binding energy data of medium and heavy nuclei.     

Synthesis of antibacterial and antifungal cobalt(II), copper(II), nickel(II) and zinc(II) complexes with bis‐(1,1′‐disubstituted ferrocenyl)thiocarbohydrazone and bis‐(1,1′‐disubstituted ferrocenyl)carbohydrazone

The condensation reaction of 1,1′‐diacetylferrocene with thiocarbohydrazide and carbohydrazide to form bis‐(1,1′‐disubstituted ferrocenyl)thiocarbohydrazone and bis‐(1,1′‐disubstituted ferrocenyl)carbohydrazone has been studied. The compounds obtained have been further used as ligands for their ligand and antimicrobial properties with cobalt(II), copper(II), nickel(II) and zinc(II) metal ions. The compounds synthesized have been characterized by physical, spectral and analytical methods and have been screened for antibacterial activity against Escherichia coli, Bacillus subtillis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi, and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using the agar well‐diffusion method. All the compounds synthesized have shown good affinity as antibacterial and antifungal agents, which increased in most of the cases on complexation with the metal ions. Copyright © 2004 John Wiley & Sons, Ltd.     

Quantitation by fast-atom bombardment mass spectrometry: assay of cytidine 3',5'-cyclic monophosphate-responsive protein kinase.

A protein kinase, stimulated by cytidine 3',5'-cyclic monophosphate, is conventionally assayed by monitoring the incorporation of radiolabelled phosphate from adenosine triphosphate into a histone substrate. Here the assay of the protein kinase is carried out by positive-ion fast-atom bombardment mass spectrometric analysis of the enzyme incubation mixture after the reaction has been terminated. The data so obtained show good agreement with data obtained by the conventional radiometric assay: the intrinsic advantage of the mass spectrometric assay is the capacity for multiple component monitoring; the ability of the kinase to bind competing cyclic nucleotides together with integral adenosine triphosphatase (ATPase) and phosphodiesterase activity can also be assessed.     

Kinetic studies on the reaction of phthalimide with ethane-1,2-diamine

General base-catalyzed and uncatalyzed nucleophilic cleavage of both unionized (SH) and ionized (S^–) phthalimide have been observed in ethane-1,2-diamine buffer solutions of pH 7.46–8.60. General base catalysis appears to be insignificant in the pH range of 9.17–10.10.     

199Hg and63,65Cu NMR studies of mercury based high-T c superconductors

Hg-oxide ceramic high temperature superconductors were studied by¹⁹⁹Hg and^63,65Cu NMR spectroscopy. Room temperature spectra, spin-spin and spin-lattice relaxation times of samples with different superconducting transition temperatures are presented. A spin-lattice relaxation time ofT ₁=35 msec and a spin-spin relaxation time ofT ₂=1.6 msec were found for the¹⁹⁹Hg NMR. All samples exhibit similar characteristic powder spectra caused by an axially symmetric¹⁹⁹Hg spin interaction. The isotropic value and the anisotropy of the tensor relative to solid HgCl₂ as a standard substance is estimated. Furthermore, results of^63,65Cu NMR measurements at a temperature of 4.2 K which exhibit a typical powder line shape (forI=3/2) are presented.