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Puducherry, India

Pondicherry University is a central university in Puducherry, India. Founded in 1985 by the Government of India, the university is a collegiate university with a jurisdiction spread over the Union Territories of Puducherry, Lakshadweep and Andaman and Nicobar Islands.It has 35000 students in its 87 affiliated colleges including 27,000 students in the distance education mode. The current strength of students studying on-campus stands at 6500. It has introduced innovations like the Choice-based Credit System and on-line admission for postgraduate studies. Pondicherry University is ranked as one of the top ten Universities in India based on the survey conducted on 2013. Wikipedia.

Anatase nanoparticles, Co xTi 1-xO 2-δ (x = dopant density in at % and δ = concentration of oxygen vacancy in the lattice) were synthesized using UV (' = 254 nm)-induced photoreduction of surface preadsorbed cis-[Co III(en) 2(MeNH 2)Cl] 2+ complex ion on nanoscale TiO 2 particle surfaces in an aqueous solution. Photogenerated dopant, Co II, has successfully implanted in the semiconductor host lattice, preserving anatase crystal phase without the formation of impurity phase like rutile. Such materials termed as diluted magnetic semiconductors (DMSs), if realized without undesirable phases, are projected to have significant implications for the evolving fields of spintronics and advanced magneto-optics. The light dosage was systematically varied to prepare nanostructured semiconductor particles with varying dopant density in the anatase matrix leading to: x%,Co/nano-TiO 2; 0.91 ≤ x ≤ 1.26 at % nonstoichiometric compound. The compound has been found to show altered optical, compositional, and room-temperature ferromagnetic properties with respect to the undoped TiO 2 nanoparticles. X-ray diffraction measurements showed characteristic anatase reflections and supplied information about the absence of coexisting rutile impurity phase. The nanoparticles are ferromagnetic, having their hysteresis loops in the range -4000 Oe < H < +4000 Oe with the specific magnetizations of (14.40 to 0.196) × 10 -3 μ B/ Co II at 300 K. However, the magnetic property depends critically on oxygen vacancy (V 0 O, V + O) and the Co content. A combined study of PL, XRF, SEM-EDX, HRTEM, XPS, and Raman techniques was used to investigate the size, dopant-distribution, composition, and surface structure. Cobalt dopant is predominantly substitutional, Co II sub in anatase lattice and in +2 formal oxidation state. SEM and HRTEM images revealed obvious variations in the surface morphology of raw and Co implanted anatase. This strategy provides an alternative route to synthesize nanosized phase pure anatase x%,Co/nano-TiO 2 showing room temperature ferromagnetism, which is expected to open up a general method for the synthesis of other transition-metal-doped nano-TiO 2. © 2011 American Chemical Society.

Bhowmik R.N.,Pondicherry University
Journal of Magnetism and Magnetic Materials | Year: 2011

The present paper shows that bulk La0.67Ca 0.33MnO3 (LCMN) sample of micron size particles is a typical ferromagnet and magnetic properties of LCMN samples with particle size in the nanometer scale are better described in the frame work of a ferrimagnetic structure. Detailed analysis of the temperature dependence of the inverse of paramagnetic susceptibility has confirmed the signature of ferrimagnetism in the nano-sized particles of LCMN. We have explained the observed ferrimagnetism as an effect of modified magnetic properties in the coreshell spin structure of LCMN particles, irrespective of the nanocrystalline and amorphous phase of the material. © 2010 Elsevier B.V. All rights reserved.

Major, trace and REE compositions of sediments from the upper Ganga River and its tributaries in the Himalaya have been examined to study the weathering in the Himalayan catchment region and to determine the dominant source rocks to the sediments in the Plains. The Ganga River rises in the Higher Himalaya from the Higher Himalayan Crystalline Series (HHCS) bedrocks and traverses over the Lesser Himalayan Series (LHS) and the Himalayan foreland basin (Siwaliks) rocks before entering into the Gangetic Plains. The major element compositions of sediments, reflected in their low CIA values (45.0-54.7), indicate that silicate weathering has not been an important process in the Himalayan catchment region of the Ganga River. Along the entire traverse, from the HHCS through LHS and the Siwaliks, the sediments from the tributaries and the mainstream Ganga River show higher Na2O, K2O, CaO and silica. This, and the higher ratios of La/Sc, Th/Sc and lower ratios of Co/Th, suggest that the source rocks are felsic. The fractionated REE patterns and the significant negative Eu anomalies (Eu/Eu* = 0.27-0.53) indicate highly differentiated source. Moreover, the comparison of the sediments with different source rock lithologies from the HHCS and the LHS for their major elements clearly suggests that the HHCS rocks were the dominant source. Further, comparison of their UCC (upper continental crust) normalized REE patterns suggests that, among the various HHCS rocks, the metasediments (para-gneiss and schist) and Cambro-Ordovician granites have formed the major source rocks. The Bhagirathi and Alaknanda River sediments are dominantly derived from metasediments and those in the Mandakini River from Cambro-Ordovician granites. The resulting composition of the sediments of the Ganga River is due to the mixing of sediments supplied by these tributaries after their confluence at Devprayag. No further change in major, trace and rare earth element compositions of the sediments of the Ganga River after Devprayag up to its exit point to the Plains at Haridwar, suggests little contribution of the Lesser Himalayan and Siwalik rocks to the Ganga River sediments. © 2009 Elsevier B.V. All rights reserved.

Abbasi T.,Pondicherry University | Abbasi S.A.,Pondicherry University
Renewable and Sustainable Energy Reviews | Year: 2010

Biomass is the first-ever fuel used by humankind and is also the fuel which was the mainstay of the global fuel economy till the middle of the 18th century. Then fossil fuels took over because fossil fuels were not only more abundant and denser in their energy content, but also generated less pollution when burnt, in comparison to biomass. In recent years there is a resurgence of interest in biomass energy because biomass is perceived as a carbon-neutral source of energy unlike net carbon-emitting fossil fuels of which copious use has led to global warming and ocean acidification. The paper takes stock of the various sources of biomass and the possible ways in which it can be utilized for generating energy. It then examines the environmental impacts, including impact vis a vis greenhouse gas emissions, of different biomass energy generation-utilization options. © 2009 Elsevier Ltd. All rights reserved.

Narayanan K.B.,Pondicherry University | Sakthivel N.,Pondicherry University
Advances in Colloid and Interface Science | Year: 2010

An array of physical, chemical and biological methods have been used to synthesize nanomaterials. In order to synthesize noble metal nanoparticles of particular shape and size specific methodologies have been formulated. Although ultraviolet irradiation, aerosol technologies, lithography, laser ablation, ultrasonic fields, and photochemical reduction techniques have been used successfully to produce nanoparticles, they remain expensive and involve the use of hazardous chemicals. Therefore, there is a growing concern to develop environment-friendly and sustainable methods. Since the synthesis of nanoparticles of different compositions, sizes, shapes and controlled dispersity is an important aspect of nanotechnology new cost-effective procedures are being developed. Microbial synthesis of nanoparticles is a green chemistry approach that interconnects nanotechnology and microbial biotechnology. Biosynthesis of gold, silver, gold-silver alloy, selenium, tellurium, platinum, palladium, silica, titania, zirconia, quantum dots, magnetite and uraninite nanoparticles by bacteria, actinomycetes, fungi, yeasts and viruses have been reported. However, despite the stability, biological nanoparticles are not monodispersed and the rate of synthesis is slow. To overcome these problems, several factors such as microbial cultivation methods and the extraction techniques have to be optimized and the combinatorial approach such as photobiological methods may be used. Cellular, biochemical and molecular mechanisms that mediate the synthesis of biological nanoparticles should be studied in detail to increase the rate of synthesis and improve properties of nanoparticles. Owing to the rich biodiversity of microbes, their potential as biological materials for nanoparticle synthesis is yet to be fully explored. In this review, we present the current status of microbial synthesis and applications of metal nanoparticles. © 2010 Elsevier B.V. All rights reserved.

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