Magnetic fractionation, chemical, and structural analyses prove that alteration of ilmenite from Manavalakurichi deposit extends only up to the formation of pseudorutile with traces of rutile. The data indicate that ferrous to ferric iron transformation, ferric iron oxide formation, and iron removal contribute to the alteration sequence. The first two highly magnetic fractions are not unaltered ilmenite. A reduction in ilmenite unit cell volume indicates the ferrous-ferric conversion occurred during alteration.

In this numerical study, the role of hyper-mixers on supersonic mixing is investigated for six different strut configurations. To this end, 3D, compressible, turbulent, non-reacting flow calculations with air as the secondary injectant have been carried out. A qualitative comparison of the predictions with experimental results is made through Schlieren and Mie scattering images. A quantitative evaluation of the predictions is made by comparison with experimentally measured exit stagnation pressure, wall static pressure and the degree of unmixedness. Based on these results, three strut configurations have been selected for carrying out simulations with hydrogen as the injectant. Results from the hydrogen simulations are compared with the predictions using air and also across the strut configurations. The results clearly demonstrate that castellated strut configurations are very effective in enhancing mixing in such high speed flows.

Prior to 2009 dengue fever had not been reported in the Andaman and Nicobar archipelago. In 2009, a few patients with dengue fever-like illness were reported, some of whom tested positive for dengue antibodies. In 2010, 516 suspected cases were reported, including some with dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS); 80 (15·5%) were positive for dengue antibodies. DENV RNA was detected in five patients and PCR-based typing showed that three of these belonged to serotype 1 and two to serotype 2. This was confirmed by sequence typing. Two clones of dengue virus, one belonging to serotype 1 and the other to serotype 2 appeared to be circulating in Andaman. Emergence of severe diseases such as DHF and DSS might be due to recent introduction of a more virulent strain or because of the enhancing effect of sub-neutralizing levels of antibodies developed due to prior infections. There is a need to revise the vector-borne disease surveillance system in the islands.

The Precambrian–Cambrian boundary problem is being studied in an areno-argillaceous sequence in the Kashmir and Spiti Valley, Northwest Himalaya, India. In Kashmir, a rich and diversified microbiota – cryptarchs and algae of the Late Precambrian, and low Lower Cambrian trace fossils are recorded. In the Spiti Valley, the yield of microbiota is poor and the trace fossils are late Lower Cambrian.

We report the fabrication of Mg-doped NdBCO generic seed crystals, which have been developed recently for the fabrication of any rare earth (RE) based (RE)-Ba-Cu-O single-grain superconductor, with a wide range of Nd1+xBa2-xCu3-yMgyO7-δ compositions. Three basic characteristics of the seed crystals required for effective seeding of bulk (RE)BCO materials were studied in detail. We report the chemical, crystallographic, microstructural, and superconducting properties of the seeds and demonstrate clearly their potential to process various (RE)BCO superconductors in single-grain form. The melting point, volume fraction of Mg-rich inclusions in the bulk microstructure, and the chemical composition of the Nd1+xBa2-xCu3-yMgyO7-δ superconducting matrix of the seed crystals were studied as a function of initial MgO content. Finally, the suitable range of MgO-content within the generic seed crystal that controls effectively the orientation of the seeded grain without compromising its superconducting properties relative to those of the Mg-free compound is identified based on the wide range of seed crystal compositions investigated.

ESR, IR, optical absorption and photoluminescence spectra of Ho3+ doped tungsten phosphate glasses modified with three different modifier oxides viz., PbO, ZnO and CaO have been studied. The ESR spectral studies indicate tungsten ions are present in W5+ state in all the three glasses with the highest concentration in CaO modified glasses. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt (JO) parameters $\Omega_2$ , $\Omega_4$ and $\Omega_6$ have been evaluated. The JO theory could successfully be applied to characterise the absorption and luminescence spectra of these glasses. From this theory various radiative properties like radiative transition probabilities, A, branching ratios, $\beta_r$ , the radiative lifetimes, $\tau_R$ , and the emission cross-sections, σ E , for various emission levels of Ho3+ in these glasses have been determined and reported. An attempt has also been made to throw some light on the environment of Ho3+ ions in all the three glasses.

The natural history of human filarial infections leading to development of disease has been a subject of intense debate. The models proposed so far have largely been based on cross-sectional data on microfilariae (Mf) and disease prevalence in filariasis endemic areas. In an attempt to study the parasitological and clinical consequences of filarial infection in Beldal (Orissa, India), an area endemic for Bancroftian filariasis, cohorts of 59 asymptomatic Mf carriers (AS) and 187 asymptomatic and amicrofilaraemic subjects or ‘endemic normals’ (‘EN’), were followed-up and a fraction (73% and 46% respectively) re-examined after 13 years to monitor (a) Mf prevalence, (b) Mf density, (c) circulating filarial antigen (CFA) and (d) chronic disease manifestations. The Mf prevalence and density were also monitored in Mf carriers after 1 and 4 years. Both Mf prevalence and density decreased progressively in the cohort of Mf carriers over a period of 13 years in Beldal. Only 37% of them continued to be microfilaraemic and the Mf density in these subjects was only 10% of the original level. However, loss of circulating Mf in this cohort did not result in loss of CFA and 95% remained CFA positive regardless of Mf status. About 23% of males in the ‘EN’ cohort developed hydrocoele while only 5·7% of male Mf carriers, who were not treated with DEC, had developed hydrocoele after 13 years. A cohort of Mf carriers in another area, Jatni, was also examined after 10 years to study the parasitological and clinical outcome. In this area, about 59% of the Mf carriers continued to be microfilaraemic after 10 years. These results reveal that in Mf carriers adult filarial worms persist for several years and that loss of circulating Mf with or without chemotherapy with DEC (single 12-day course) does not influence adult worm survival. The findings have been discussed in the context of ‘static’ and ‘dynamic’ models describing the relationship between infection and disease in human filariasis.

Joining of melt-textured YBa2Cu3O7-δ (Y123) grains has been achieved without use of an external agent. The technique uses barium-cuprate liquid phase released from platelet boundaries to mediate the growth of Y123 at the interface between two grains. The epitaxial nature and high quality of the growth was determined by optical and transmission electron microscopy. The composition of Ba–Cu–O phases found in some parts of the joins was determined by electron probe microanalysis. A clean low-angle join was found to consist of a grain boundary with dislocation networks and facets. Transport critical current measurements on this type of join revealed strongly coupled behavior. The technique shows promise for the joining of melt-textured material for power engineering applications.

In leaf disc choice assays and topical application experiments, the neem (Azadirachta indica) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin were found to be potent antifeedants and growth inhibitors to the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). Azadirachtin was most potent in both respects. Gross dietary utilisation (efficiency of conversion of ingested food) of H. armigera was also decreased following topical application as well as after treatment in the diet. Growth inhibition in topically treated H. armigera may be primarily attributed to decreased food intake. The antifeedant and growth-inhibitory effects of the neem limonoids are discussed.

Pupation patterns, viz. larval ripening, pharate pupal and pupal formation were diurnally predominant in the silkworm, Bombyx mori L. (PM × NB4D2), under different photoperiodic conditions. Under continuous light (LL), the rhythm damped-out. Upon circular statistical treatment of the data, the peaks expressed two distinct modes short day and long day resultant groups and these phenomena are distinct for pharate pupal formation. Duration between larval ripening and pharate pupal formation, as also between pharate pupal and pupal formation was influenced by different light/dark conditions. Duration between larval ripening and pupal formation was significantly (P < 0.05) less under LD 11:13 as compared to LD 12:12.

Synthesis of a new fully conjugated polydiacetylene i.e. poly(l,4-bis(3-quinolyl)-l,3-butadiyne) is described. Reflectance spectra of partially polymerised samples and the polymer are reported. The spectra show long wavelength absorption band at 750 nm. with the visible absorption edge above 800 nm. DC electrical conductivity measurements on pristine and Iodine doped Poly-DQ are reported. The results are discussed in terms of side group - backbone electronic interactions.