<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

(SoNS) School of Natural Sciences

The structural and magnetic properties of dilutely doped 3d elements in pulsed laser deposition (PLD) grown HfO 2 high-k dielectric thin films were studied. Monoclinc phase of HfO 2 was stabilized by Co- and Fe- substitution at significantly low growth temperature. High purity HfO 2, CoO and Fe 2O 3 powders were mixed throughly in the required ratio for 5mol% Co and Fe doping in HfO 2. The results from atomic force microscopy showed possible segregation of Fe 3O 4 phase in the form of nanoscale mounds.

World University root node

Physics

Materials Research Society Symposium Proceedings

Search for magnetism in Co and Fe-doped HfO 2 thin films for potential spintronic applications

A blue shifted photoluminescent emission in bis(2-(2′-hydroxyl phenyl)benzthiazolate)zinc (II) complex, ZBZT, arises out of the dimeric structure, typical of the localized electron density around the non-bridged ligand in the excited state of the complex. An average decay lifetime of 4.8 and 3.0 ns for the ligand and the complex, respectively indicates an energy transfer from the ligand to the metal. A PL quantum efficiency of about φ ZBZT=0.45 in DMF solution is observed, in comparison to the Alq 3, complex, φ Alq3=0.116. Semi empirical ZINDO/S-SCF-CI calculations support the dominance of non-bridged ligand moiety in controlling the photoluminescent properties. An unusually broad white light (FWHM ∼220 nm) electroluminescent emission in the two layer device structure brings out the features of an exciplex formation between the active layer ZBZT/TPD interface, which is studied at different current densities. Such a broadened emission is verified for different thicknesses of the active layer substantiating the role of exciplex formation. © 2004 Elsevier Ltd. All rights reserved.

Solid State Communications

Electroluminescent properties of dimeric bis(2-(2′-hydroxyl phenyl)benzthiazolate)zinc (II) complex

In order to understand the molecular mechanisms involved in the gene-for-gene type of pathogen resistance, high-resolution genetic and physical mapping of resistance loci is required to facilitate map-based cloning of resistance genes. Here, we report the molecular mapping and cloning of a dominant gene (Pi-kh) present in the rice line Tetep, which is associated with resistance to rice blast disease caused by Magnaporthe grisea. This gene is effective against M. grisea populations prevalent in the Northwestern Himalayan region of India. Using 178 sequence tagged microsatellite, sequence-tagged site, expressed sequence tag and simple sequence repeat (SSR) markers to genotype a population of 208 F2 individuals, we mapped the Pi-kh gene between two SSR markers (TRS26 and TRS33) which are 0.7 and 0.5 cM away, respectively, and can be used in marker-assisted-selection for blast-resistant rice cultivars. We used the markers to identify the homologous region in the genomic sequence of Oryza sativa cv. Nipponbare, and a physical map consisting of two overlapping bacterial artificial chromosome and P1 artificial chromosome clones was assembled, spanning a region of 143,537 bp on the long arm of chromosome 11. Using bioinformatic analyses, we then identified a candidate blast-resistance gene in the region, and cloned the homologous sequence from Tetep. The putative Pi-kh gene cloned from Tetep is 1.5 kbp long with a single ORF, and belongs to the nucleotide binding site-leucine rich repeat class of disease resistance genes. Structural and expression analysis of the Pi-kh gene revealed that its expression is pathogen inducible. © Springer-Verlag 2005.

Life Sciences

Molecular Genetics and Genomics

High-resolution mapping, cloning and molecular characterization of the Pi-kh gene of rice, which confers resistance to Magnaporthe grisea

In eukaryotes, the origin recognition complex (ORC) is essential for the initiation of DNA replication. The largest subunit of this complex (ORC1) has a regulatory role in origin activation. Here we report the cloning and functional characterization of Plasmodium falciparum ORC1 homolog. Using immunofluorescence and immunoelectron microscopy, we show here that PfORC1 is expressed in the nucleus during the late trophozoite and schizont stages where maximum amount of DNA replication takes place. Homology modelling of the carboxy terminal region of PfORC1 (781-1033) using Saccharomyces pombe Cdc6/Cdc18 homolog as a template reveals the presence of a similar AAA+ type nucleotide-binding fold. This region shows ATPase activity in vitro that is important for the origin activity. To our knowledge, this is the first evidence of an individual ORC subunit that shows ATPase activity. These observations strongly suggest that PfORC1 might be involved in DNA replication initiation during the blood stage of the parasitic life cycle. © 2005 Elsevier Inc. All rights reserved.

Biochemical and Biophysical Research Communications

Expression and characterization of human malaria parasite Plasmodium falciparum origin recognition complex subunit 1

The relation between electrically active defects in organic and polymeric semiconductor materials and degradation of devices such as loss of luminance is currently not understood. In this paper, we study defect related charge processes using electrical transients in polymeric and organic diodes. We monitor slow charging and discharging currents as a function of time for both virgin and electrically aged devices. The current transients are analyzed spectroscopically in time domain using a technique called Time Analyzed Transient Spectroscopy, which is similar to DLTS in its implementation. We observe highly stretched exponentials over 3-4 orders of magnitude in time up to thousands of seconds indicating existence of large distribution in time constants in aged PLED devices. We demonstrate ability to distinguish between different mechanisms of charge storage related to defect related processes in typical OLED and PLED. © 2005 Materials Research Society.

Electrical transient based defect spectroscopy in polymeric and organic semiconductors

We have characterized the phase behavior of mixtures of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and the organic salt 3-sodium-2-hydroxy naphthoate (SHN) over a wide range of surfactant concentrations using polarizing optical microscopy and X-ray diffraction. A variety of liquid crystalline phases, such as hexagonal, lamellar with and without curvature defects, and nematic, are observed in these mixtures. At high temperatures the curvature defects in the lamellar phase are annealed gradually on decreasing the water content. However, at lower temperatures these two lamellar structures are separated by an intermediate phase, where the bilayer defects appear to order into a lattice. The ternary phase diagram shows a high degree of symmetry about the line corresponding to equimolar CTAB/SHN composition, as in the case of mixtures of cationic and anionic surfactants. © 2005 American Chemical Society.

Langmuir

Phase behavior of concentrated aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium hydroxy naphthoate (SHN)

In this paper, effects of lead doping on the lattice response and phase transitions of Sr1-xPbxBi2Nb2O 9 (x=0.0-0.5 in steps of 0.1) ferroelectric ceramics are reported. It is observed that structure attains more tetragonality with doping of lead up to 40%. Increased orthorhombic distortion is observed for undoped SEN and 50 at.% lead substituted SBN. Phase transitions for all samples were studied using Curie temperature measurements and are explained in terms of lattice response of these ceramics. Sample with x = 0.5 shows decreased tetragonal strain and Curie temperature. Relationship of polarization with lattice response is discussed. © 2004 Elsevier Ltd. All rights reserved.

Structural distortion and phase transition studies of Aurivillius type Sr1-xPbxBi2Nb2O9 ferroelectric ceramics

By using the point canonical transformation approach in a manner distinct from previous ones, we generate some new exactly solvable or quasi-exactly solvable potentials for the one-dimensional Schrödinger equation with a position-dependent effective mass. In the latter case, SUSYQM techniques provide us with some additional new potentials. © EDP Sciences.

Fulltext

Europhysics Letters

New approach to (quasi-)exactly solvable Schrödinger equations with a position-dependent effective mass

We exploit the hidden symmetry structure of a recently proposed non-Hermitian Hamiltonian and of its Hermitian equivalent one. This sheds new light on the pseudo-Hermitian character of the former and allows access to a generalized quantum condition. Special cases lead to hyperbolic and Morse-like potentials in the framework of a coordinate-dependent mass model. © 2005 IOP Publishing Ltd.