A new layered triangular antiferromagnet Li4FeSbO6: spin order, field-induced transitions and anomalous critical behavior.

Structure, electrochemical, magnetic and resonance properties of new layered antimonate Li(4)FeSbO(6) were comprehensively studied using powder X-ray diffraction, cyclic voltammetry, magnetic susceptibility, heat capacity, electron spin resonance and Mössbauer spectroscopy. In the crystal structure the iron ions form the triangular network within (LiFeSbO(6))(3-) layers alternating with nonmagnetic lithium layers. The electrochemical activity studied implies an Fe(3+)/Fe(4+) redox couple at 4.

Participation of the intracellular enzymes in the control of mutational processes : Part 4: the role of UV-specific endonuclease and medium composition in the induction of genic mutations in Escherichia coli.

The influence of UV-specific endonuclease and medium composition on the frequency and spectrum of genic mutations in Escherichia coli KI2 uvr (+) (with normal repair enzymes) and urv A6 (defective in UV-specific endonuclease) was studied. Mutations at the locus glu (gene controlling assimilation of glucose) were induced by ultra-violet irradiation and hydroxylamine treatment. To identify mutant colonies, triphenyl tetrazolium chloride (TTC) was added to the medium since it coloured the mutant colonies bright crimson and readily permitted distinction between pure mutant clones (complete mutations) and mixed clones (mosaic or sector mutations).