Ionic interactions in aqueous electrolyte-polyelectrolyte mixtures: Comparisons with mixtures of sodium chloride with the model electrolyte sodiumpara-ethylbenzenesulfonate at 25°C

Osmotic coefficients for aqueous mixtures of sodium chloride with sodiumpara-ethylbenzenesulfonate NapEBS and lithiumpara-ethylbenzenesulfonate LipEBS with NapEBS obtained by the gravimetric isopiestic vapor pressure comparison method are interpreted with the Scatchard neutral-component and with the Pitzer ion-component equations. Ionic and mean ionic activity coefficients for Na⁺ and Cl^– ions and for NaCl, respectively, were also determined with an electrochemical cell. The ±(NaCl) values at constant unit ionic strength,I=1.00, were compared with those computed from osmotic-coefficient measurements. Strong anion-anion interactions were observed in the NaCl-NapEBS mixtures.     

Characterising the geometric diversity of functional groups in chemical databases

Summary We have developed a program, HookSpace, which provides a simplistic approach to assessing the diversity of molecular databases. The spatial relationship between pairs of intramolecular functional groups can be analysed in a variety of ways to provide both qualitative and quantitative measures of diversity. Results are described and contrasted for two commercially available databases and a combinatorial library of benzodiazepam derivatives. HookSpace highlights the main differences in molecular content of these data sets.     

The synthesis of XTT: A new tetrazolium reagent that is bioreducible to a water-soluble formazan

A new tetrazolium salt, XTT, has been synthesized. XTT is reduced by a considerable variety of cell lines to a water-soluble formazan. XTT appears to merit further investigation as a reagent for broader application to cell culture assay systems.     

Elastic scattering of vector polarized deuterons by 4He

The vector analyzing power iT₁₁ for deuterons elastically scattered by ⁴He has been measured for c.m. angles between 51.8° and 158.9° and deuteron energies in the range 11.5 to 17 MeV. The results show that d-α scattering is a convenient analyzer for deuteron vector polarization in the energy range investigated, since the angular dependence of iT₁₁ is fairly insensitive to energy and the magnitude of iT₁₁ is quite large at some angles.     

STABILITY PROPERTIES IN A MODEL OF FORAGE-UNGULATE-PREDATOR INTERACTIONS

This paper explores stability in a three differential equation model of ungulates, their forage and their predators. Stability most depends on the feeding efficiency of exploiters relative to the growth potential of those exploited. Stable, natural systems probably require relatively inefficient exploitation, refuges for the exploited population or prey switching by generalist exploiters. Increased exploitation of ungulates enhances ungulate-forage stability but, lacking prey refugia, eventually overexploits the ungulates. Multiple, stable equilibria representing sustained ungulate yield and ungulate extinction probably characterize big game. Under traditional management, game populations will approach the zone of attraction of the second of these equilibria.     

Four-wave interactions in plasmas

The interaction of four waves in a warm magnetized plasma is studied using a Lagrangian formalism. General expressions for coupling coefficients are presented and the coupled-mode equations describing the interaction are derived.