Electron density and localizability in BH

Three partitioning methods are compared for the molecule BH. They are by minimum fluctuations, intersections of isodensity contours for localized molecular orbitals, and the virial partitioning method. The first two methods were found to partition BH very similarly, such that the centroids of charge can be calculated for these loges defined by minimum fluctuation and using the localized molecular orbitals.     

Kinetics of partly diffusion controlled reactions. X. Use of a high pressure cell in fluorescence quenching experiments

The increase of the pressure over a liquid results in an increase of its viscosity, which makes possible the study of the mechanism of diffusion-controlled, or not, fluorescence quenching processes. This technique has been applied to the quenching of the fluorescence of two substituted anthraquinones by N,N-dimethyl-p-toluidine in acetonitrile solution.

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Linear operators strongly preserving digraphs whose maximum cycle length

We characterize those linear operators L such that for all digraphsD,L(D) has maximal cycle length L if an only if D has maximum cycle length L. We do this for L =0 and L = 1, the cases L ≤2 having been done previously.     

Applying robust regression to insurance

A statistical procedure is called robust if it is insensitive to the occurence of gross errors in the data. The ordinary least squares regression technique does not satisfy this property, because even a single outlier can totally offset the result. Therefore, the least trimmed squares (LTS) technique is introduced, which can resist the effect of a large percentage of outliers. The latter method is illustrated on data concerning life insurance, pension funds, health insurance, and inflation.     

Effect of aniline derivatives on the extraction of cobalt with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one in toluene

Summary The effect of aniline derivatives [4-methylaniline=4-toluidine, 3,4-dimethylaniline=3,4-xylidine, N,N-dimethylaniline and tribenzylamine (Am)] on the extraction of cobalt from sulphate, nitrate and perchlorate aqueous media of 1.0M ionic strength with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HL) in toluene, has been quantitatively studied. With both primary amines a synergic effect was found owing to theAmH·CoL ₃ ion pair extraction. TheAmH·CoL ₃ average formation constant, from CoL ₂ andAmH·CoL, was logK _s =3.7 and 3.8 forAm=4-toluidine and 3,4-xylidine respectively. With N,N-dimethylaniline and tribenzylamine which are poorly protonated in the cobalt extractionpH range (4–6), no noticeable synergism was observed.On leave from: Department of Inorganic Chemistry, Chemical Faculty, Ignacy Lukasiewicz Technical University, PL-35-959 Rzeszow, Poland     

EXPRESSION OF AN Anacystis nidulans PHOTOLYASE GENE IN Escherichia coli; FUNCTIONAL COMPLEMENTATION AND MODIFIED ACTION SPECTRUM OF PHOTOREACTIVATION

The Anacystis nidulans photolyase gene inserted in an expression vector plasmid was introduced into Escherichia coli cells and the production of Anacystis photolyase protein was confirmed by reaction with antibodies raised against photolyase purified from A. nidulans cells. The Anacystis photolyase functioned in photoreactivation repair defective E. coli cells. The E. coli transformants exhibited an action spectrum with a maximum around 380 nm similar to that of E. coli photolyase in contrast with the action spectrum of A. nidulans cells which has a maximum at 437 nm. These results indicate that the Anacystis photolyase produced in E. coli cells has enzymatic activity in spite of the apparent lack of its intrinsic 8-hydroxy-5-deazaflavin cofactor.     

An optical study of thin interfacial liquid films using total reflection of light

The light totally reflected at the interface between a glass prism and a liquid (water) of lower index can be partly transmitted as a droplet of liquid of larger index (oil) approaches this interface. By using the variation of the reflected intensity, one can study the static structure and the thickness variation of the intermediate water film in a range of thickness of a few 10 Å to 10² Å. A preliminary experiment is presented together with the optical technique.