The role of hydrophobicity in the Ames test. The correlation of the mutagenicity of nitropolycyclic hydrocarbons with partition coefficients and molecular orbital indices

A set of 20 nitropolycyclic aromatic hydrocarbons, whose mutagenicity has been determined in the Ames test, has been studied using octanol-water partition coefficients (P) as a measure of relative hydrophobicity and molecular orbital energies to account for variation in their electronic characteristics. A good structure-activity relationship was found using log P and ?_LUMO . The latter were taken from the results of ab initio calculations performed by Maynard, Pedersen, Posner, and McKinney [7] and were also calculated by the MNDO method. The dependence of mutagenicity on hydrophobicity was found to be similar to that observed for triazenes [2]. ?_LUMO values calculated by MNDO and STO -3G were found to be strongly correlated, and the role of hydrophobicity in correlating mutagenicity was not significantly affected by the molecular orbital model employed.     

Mixed fluoroamine complexes of chromium(III)

Summary Mixed difluoro(diamine)(diamme)chromium(III) complexes have been synthesized with ethylenediamine (en), 1,3 propanediamine(tn) and 1,2-cyclohexanediamine(chxn):trans-[CrF₂(aa)(bb)]Br (aa=en, bb=tn; aa=tn, bb= chxn) andcis-[CrF₂(aa)(bb)]Br (aa=en, bb=chxn). The corresponding fluoroaqua(diamine) (diamine)chromium(III) complexes have been prepared by acid hydrolysis as perchlorate or iodide salts. All have been characterized by chemical analysis, electronic and i.r. spectra and conductivity measurements.     

A new strongly regular graph

A combinatorial construction is given of a strongly regular graph with parameters (v, k, λ, μ) = (280, 117, 44, 52) which was previously unknown.     

Noncommutative Jordan C*-algebras

We introduce noncommutative JB*-algebras which generalize both B*-algebras and JB*-algebras and set up the bases for a representation theory of noncommutative JB*-algebras. To this end we define noncommutative JB*-factors and study the factor representations of a noncommutative JB*-algebra. The particular case of alternative B*-factors is discussed in detail and a Gelfand-Naimark theorem for alternative B*-algebras is given.     

The revised structure of mortonin

The structure 1 previously proposed tor mortonin, is revised to 2 based on spectroscopic and chemical evidence, and on biogenetic considerations.     

The biobjective absolute center problem

This paper deals with the problem of determining the absolute center of a network, taking into account two objective functions. These functions consist of minimizing the maximum of the distances from any point on the network to the vertices, using two independent lengths on each edge. We propose an algorithm in polynomial time to obtain the non-dominated location points on the network, using the Kariv and Hakimi method (1979). This work was partially supported by project number 93/108 from the Dirección General de Universidades e Investigación del Gobierno de Canarias.     

Micro-Effects on Continuous-Injection Heat Conduction Calorimetry

A localized-constant model involving two capacities reliably describes two injection calorimeters: a mass-variation calorimeter and a constant-volume calorimeter (TAM 2277 by Thermometric). The model distinguishes the place and the types of dissipation, and its parameters depend on the rates and on the heat capacities of the liquids. In the case of the TAM 2277 calorimeter, the dependence between the detected heat of mixing and the injection rate is revealed. The proposed model permits the inclusion of perturbations on the baseline originating from the temperature variation of the thermostat. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthése d'héterocycles. XX. Reaction du malononitrile avec quelques cinnamonitriles

Reaction of cinnamonitriles with malononitrile, in methanolmethoxide, yield dihydropyridines, which by aromatisation give pyridines. Pyridine is directly obtained when p-nitrocinnamonitrile is used     

The crossing of N2 adsorption isotherms on CdCl2

The adsorption of N₂ at 77.7, 83.3 and 90.1 K has been obtained on a sample of CdCl₂ previously treated in vacuum at 150°C for 40 h. All adsorption isotherms, when plotted versus relative pressure, cross at a point near $\text{P}\text{P}{}_0$ = 0.15. The volume adsorbed at the crossing point is near the BET or point B monolayer volume. The crossing of the isotherms is related to the high surface homogeneity of the sample.