Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Centre for Nanotechnology Research

Gold nanoparticles have been used as a probe for the detection of various aminoglycosidic antibiotics like streptomycin, gentamycin and neomycin. The nature of interaction between these drugs and gold nanoparticles has been probed by various analytical techniques like UV-vis, FT-IR, TEM, etc. Such studies can be used for the determination of drugs in drug formulations. Further in vitro antibacterial activities of drugs capped Au nanoparticles (Au@drugs) were investigated against various strains of Gram positive and Gram negative organisms viz. Staphylococcus aureus, Micrococcus luteus, E. Coli and Pseudomonas aeruginosa. Our results suggest that gold nanoparticles could act as an effective drug carrier in drug delivery system. © 2006 Elsevier B.V. All rights reserved.

Vellore Campus

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Colloids and Surfaces A: Physicochemical and Engineering Aspects

Antibacterial efficacy of aminoglycosidic antibiotics protected gold nanoparticles-A brief study

A single step method for the synthesis of Au and Pt nanoparticles by the spontaneous reduction of chloroaurate and chloroplatinate ions using hexadecaaniline molecules has been described. The importance of this work is that hexadecaaniline acts as a multifunctional molecule that accomplishes the complexation of aqueous chloroaurate and chloroplatinate ions by phase transferring them to CHCl3 medium and their subsequent reduction to yield Au and Pt nanoparticles in organic phase. Furthermore the metal reduction is followed by polymerization of the amine to yield polyaniline, which subsequently caps the Au and Pt nanoparticles. The process of reduction of the auric and platinic metal precursors and the subsequent capping of the Au and Pt nanoparticles has been elucidated by various analytical techniques like UV-vis, X-ray diffractogram (XRD) and transmission electron micrographic (TEM) analysis. Such prepared nanoparticles are utilized for the fabrication of novel modified electrodes towards the electrocatalytic oxidation of glucose. © 2007 Elsevier B.V. All rights reserved.

Organically dispersible gold and platinum nanoparticles using aromatic amines as phase transfer and reducing agent and their applications in electro-oxidation of glucose

We observe critical phenomena in spherically symmetric gravitational collapse of Einstein Cluster. We show analytically that the collapse evolution ends either in formation of a black hole or in dispersal depending on the values of initial parameters which characterize initial density and angular momentum of the collapsing cloud. Near the threshold of black hole formation, we obtain scaling relation for the mass of the black hole and find the critical exponent value to be 3/2. We numerically confirm that there exist wide ranges of initial parameter values around the critical configuration for which the model remains shell-crossing free.

Fulltext

Progress of Theoretical Physics

Critical collapse of Einstein cluster

We examine here spherical gravitational collapse of a matter model with vanishing radial pressure and non-zero tangential pressure. It is seen analytically that the collapsing cloud either forms a black hole or disperses depending on values of the initial parameters which are initial density, tangential pressure and velocity profile of the cloud. A threshold of black hole formation is observed near which a scaling relation is obtained for the mass of black hole, assuming initial profiles to be smooth. The similarities in the behaviour of this model at the onset of black hole formation with that of numerical critical behaviour in other collapse models are indicated. © Springer Science+Business Media, LLC 2007.

General Relativity and Gravitation

Rebounce and black hole formation in a gravitational collapse model with vanishing radial pressure

In this Letter, 'recursive fitting' is applied to obtain a new parameterization of the central force field for water. As target experimental data to be reproduced, we use experimental radial distribution functions determined by neutron scattering, which provide accurate information about the internal structure of water. We show firstly, that the obtained force field reproduces correctly the geometry of water molecules and the coordination shell. Afterwards the new force field is applied to simulate some physical properties of water (diffusion coefficient and density). Finally we sketch briefly the ability of this force field, to allow for the proton transfer between a hydronium ion and a water molecule in a hydrated Nafion membrane. © 2007 Elsevier B.V. All rights reserved.

Chemical Physics Letters

A new reactive potential for the molecular dynamics simulation of liquid water

Dynamical Einstein cluster is a spherical self-gravitating system of counterrotating particles, which may expand, oscillate and collapse. This system exhibits critical behaviour in its collapse at the threshold of black hole formation. It appears when the specific angular momentum of particles is tuned finely to the critical value. We find the unique exact self-similar solution at the threshold. This solution begins with a regular surface, involves timelike naked singularity formation and asymptotically approaches a static self-similar cluster. © 2007 Springer Science+Business Media, LLC.

Analytical solutions for black-hole critical behaviour

A one-pot synthesis of Au and Pt nanoparticles by the spontaneous reduction of chloroaurate and chloroplatinate ions using tetraaniline molecules has been elucidated. The importance of this work is that tetraaniline acts as a multifunctional molecule that accomplishes the complexation of aqueous chloroaurate and chloroplatinate ions by phase transferring them to organic medium and their subsequent reduction to yield Au and Pt nanoparticles in organic phase. The metal reduction is followed by polymerization of the amine to yield polyaniline, which subsequently caps the Au and Pt nanoparticles. Various analytical techniques have been used for probing the process of reduction of auric and platinic metal precursors like UV-vis, X-ray diffractogram (XRD) and transmission electron micrographic (TEM) analysis. Such prepared nanoparticles are utilized for the fabrication of novel modified electrodes towards the electrocatalytic oxidation of glucose. © 2007 Elsevier Ltd. All rights reserved.

Journal of Physics and Chemistry of Solids

Synthesis of gold and platinum nanoparticles using tetraaniline as reducing and phase transfer agent—A brief study and their role in the electrocatalytic oxidation of glucose

Uniform and stable polymer protected spherical gold nanoparticles were synthesized using glycerol as reducing agent. Further it was observed that the morphology of the particles varied from spherical to triangular prismatic gold nanoparticles when the reaction was changed from normal mode of reflux condition to microwave mode (MW) of heating. Further a brief mechanism relating the formation of prisms with the orientation of polymer and nucleation period has been discussed. Formation of triangular prismatic and spherical gold nanoparticles were characterised using UV-vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. © 2006 Elsevier B.V. All rights reserved.

One pot synthesis of polymer protected gold nanoparticles and nanoprisms in glycerol

A comparative investigation was done on the interaction of glycerol using polyaniline supported Pt nanoparticles, Pt-Pd bimetallic nanoparticles and Ru doped Pt-Pd nanoparticles fabricated on indium tin oxide (ITO) electrodes. Improvement of electrocatalytic activity on Pt was observed by modifying Pt with other metals. The oxidation of glycerol showed much less significant electrode poisoning when Ru nanoparticles was added to Pt-Pd bimetallic nanoparticles. The effect of concentration of glycerol on the oxidation current has also been investigated. Results show that nanoparticles incorporated polymer films could improve the electrocatalytic efficiency towards the oxidation of glycerol. The higher activity and stability of the composite electrodes could be due to the stabilization of metal nanoparticles in the polymeric environment and the presence of Pd and Ru nanoparticles in addition to Pt may inhibit the formation of strongly adsorbed CO species. The micrographs and elemental composition of metal dispersed polymer films were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and contact mode atomic force microscopic studies (AFM). © 2006 Elsevier B.V. All rights reserved.

Electrochemistry Communications

Pt, Pt-Pd and Pt-Pd/Ru nanoparticles entrapped polyaniline electrodes - A potent electrocatalyst towards the oxidation of glycerol

Generalizing earlier results on dust collapse in higher dimensions, we show here that cosmic censorship can be restored in some classes of gravitational collapse models with tangential pressure present, if we take the spacetime dimension to be N≥6. This is under conditions to be motivated physically, such as smoothness of initial data from which the collapse develops. The models considered here with nonzero pressure include the Einstein cluster spacetimes which have been earlier studied extensively. Our work provides a step towards an understanding of the cosmic censorship conjecture and the necessary conditions for its validity. © 2005 The American Physical Society.