Leelakrishna Reddy

Morphogenesis of ZnO nanostructures: role of acetate (COOH−) and nitrate (NO3−) ligand donors from zinc salt precursors in synthesis and morphology dependent photocatalytic properties

We have studied the anion ratio effect of acetate and nitrate ions on the formation of different morphologies of ZnO crystals in the presence of NaOH and HMTA. We have varied the concentration of zinc salt precursors as well as adopted three different methods of synthesis (chemical, ultrasonic and hydrothermal) to study their effects on the size/shape of the formed ZnO nanostructures. We found that these anions which spontaneously get introduced along with zinc salt can modify the structure depending on their ratio. The photocatalytic properties of the as obtained ZnO nanostructures (nanoflower, nanospindle and nanorod) were tested towards anionic dye methyl orange. The results show that rod like ZnO nanostructures are catalytically more reactive than nanoflowers and nanospindles. Based on these results we propose that selection of appropriate zinc salt is important to rationally design experiments for a particular morphology. Furthermore, it is also suggested that the role of other precursor salts in synergy will lead to the formation of various nanostructures and this can be extended to other metal oxides of interest for modification.

Quantum critical behavior of the (Cr86Ru14)1−xVx alloy system

Electrical resistivity, Hall effect, specific heat, and neutron diffraction measurements are used to investigate magnetic and quantum critical behavior in a commensurate spin-density-wave (CSDW) antiferromagnetic (Cr86Ru14)1−xVx alloy system. The x−T magnetic phase diagram obtained from the measurements depicts a critical point, occuring at T=0K for a critical V concentration xc=0.104. This point is classified as a CSDW-type quantum critical point using recently suggested methods for classification of quantum critical points from Hall measurements.

Gender Differences in Attitudes to Learning Science in Grade 7

Learners’ attitude to learning science plays a vitally important role with respect to career choices. This study reflects on the nature of the learners’ attitude towards science and the effect of gender. A total of 547 Grade 7 learners from an urban district of Gauteng Province (South Africa) were administered a questionnaire to probe their attitudes and interests in learning science. The questionnaire itself was a modified version of an extant questionnaire, consisting of 15 questions. Learners were requested to indicate their degree of agreement or disagreement to each of the questionnaire item, on a five-point Likert-type scale of evaluation. The results were analysed in terms of the A (affection), B (behaviour) and C (cognition) model of attitudes. The results reflect positivity on many items of the questionnaire in the learning of science for all three components of attitude. On the issue of gender differentials, there appears to be no significant difference in attitude between Grade 7 boys and girls towards learning science from a South African perspective. In terms of subject preference, boys were more inclined to study physics and chemistry, while girls had a higher preference for biology and astronomy. However, the need for a dedicated laboratory to conduct experiments for the purposes of conceptual development was identified as a priority by the learners.

Scaling of spin-density-wave effects in the quantum critical (Cr86Ru14)1−xVx alloy system

An analysis of experimental data on the electrical resistivity, Hall coefficient and electronic specific heat coefficient of a quantum critical (Cr86Ru14)1−xVx alloy system, is reported. The results give information on the role of spin-density-wave effects on the zero temperature relationships between these physical properties.