<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

We demonstrate white organic light-emitting diodes (OLEDs) having spectral width of approximately 260 nm in electroluminescence (EL) in a simple bilayer structure, consisting of TPD and zinc benzothiazole, without taking recourse to complex strategies such as blending and doping. The EL is broader than the corresponding photoluminescence (PL) of both component materials and their structures. A deconvolution of PL and EL spectra shows that as large as 60% of the broad EL emission originates from multiple exciplexes formed at the interface during electrical excitation. © 2005 American Institute of Physics.

Physics

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Applied Physics Letters

White organic light-emitting diodes based on spectral broadening electroluminescence due to formation of interfacial exciplexes

Analysis of charge density distributions in molecular crystals has received considerable attention in the last decade both from high-resolution X-ray diffraction studies and from high-level theoretical calculations. An overview of the progress made in deriving one-electron properties, intermolecular interactions in terms of the Atoms in Molecule (AIM) approach (R.F.W. Bader. Atoms in Molecules-A Quantum Theory, Clarendon, Oxford (1990), R.F.W. Bader. J. Phys. Chem., A102, 7314 (1998)) is given with special emphasis on improvements in charge density models and development of both experimental and theoretical techniques to interpret and analyse the nature of weak intermolecular interactions. The significance of the derived results from the charge density of coumarin and its derivatives have been analysed to obtain insights into the nature of intermolecular C-H⋯O, C-H ⋯π, π⋯π, C-H⋯S, and S⋯S contacts. The appearance of a 'region of overlap' to segregate hydrogen bonds from van der Waals interactions based on the criteria proposed by Koch and Popelier (U. Koch, P.L.A. Popelier. J. Phys. Chem., 99, 9747 (1995), P.L.A. Popelier. Atoms in Molecules. An Introduction, pp. 150-153, Prentice Hall, UK (2000)) and the identification of differences in energy surfaces in concomitant polymorphs of 3-acetylcoumarin are described. © 2005 Taylor & Francis.

Chemistry

Crystallography Reviews

Evaluation of weak intermolecular interactions in molecular crystals via experimental and theoretical charge densities

Evaluation of intermolecular interactions in terms of both experimental and theoretical charge density analyses has produced a unified picture with which to classify strong and weak hydrogen bonds, along with van der Waals interactions, into three regions. © The Royal Society of Chemistry 2005.

CrystEngComm

Charge density based classification of intermolecular interactions in molecular crystals

Experimental electron densities in coumarin, 1-thiocoumarin, and 3-acetylcoumarin have been analyzed based on the X-ray diffraction data at 90 K. These compounds pack in the crystal lattice with weak C-H⋯O and C-H⋯π interactions, and variations in charge density properties and derived local energy densities have been investigated in the regions of intermolecular interactions. Theoretical charge density calculations on crystals using the B3LYP/6-3 IG** method show remarkable agreement with the derived properties and energy densities from the experiment. The intermolecular interactions follow an exponential dependence of electron density and energy densities at the bond critical points. The Laplacian follows a "Morse-like" dependence on the length of the interaction line. Based on the set of criteria defined using the theory of "atoms in molecules", it has become possible to distinguish between a hydrogen bond (C-H⋯O) and a van der Waals interaction (C-H⋯π). This has resulted in the identification of a "region of overlap" in terms of electron densities, energy densities, and mutual penetration of the hydrogen and acceptor atoms with respect to the interaction length. This approach suggests a possible tool to distinguish between the two types of interactions.

Journal of Physical Chemistry A

Exploring the lower limit in hydrogen bonds: Analysis of weak C-H⋯O and C-H⋯π interactions in substituted coumarins from charge density analysis

We discuss the distribution of size and aerial density of Ge nanocrystals in a metal-oxide-semiconductor (MOS) memory structure fabricated by molecular beam epitaxy combined with rapid thermal processing; the size and aerial density of Ge nanocrystals are controlled by varying the thickness of the deposited Ge layer and the processing time. Variation of tunnel oxide thickness is demonstrated with the extension of the processing time. The effect of processing time and tunnel oxide thickness on the electrical properties of the MOS structures is investigated by high frequency capacitance-voltage measurements. © Springer-Verlag 2004.

Applied Physics A: Materials Science and Processing

Size and aerial density distributions of Ge nanocrystals in a SiO 2 layer produced by molecular beam epitaxy and rapid thermal processing

2005 International Semiconductor Device Research Symposium

Homo and heteroepitaxial growth of hexagonal and cubic Mg xZn1-xO alloys

Physical Review Letters

{Condensed Matter: Electronic Properties, etc.-Spin-Flop Ordering from Frustrated Ferro-and Antiferromagnetic Interactions: A Combined Theoretical and Experimental Study of a Mn {\ldots}}

In this paper effects of lead doping on the lattice response and phase transitions of bismuth-layered structure Sr 1-xPb xBi 2Nb 2O 9 (x = 0.0 to 0.5 in steps of 0.1) ferroelectric ceramic are reported. It is observed that structure attains more tetragonality with doping of lead up to 40%. Increased orthorhombic distortion is also observed. Curie temperatures of all samples were measured and the phase transition is explained in terms of lattice response of these ceramics. Sample with x = 0.5 shows decreased tetragonal strain and Curie temperature. Also, relationship of polarization with lattice response is discussed.

Ferroelectrics

Structural distortions and behavioural changes in phase transition of aurivillius type Sr 1-xPb xBi 2Nb 2O 9 ferroelectric

Several 6-carboethoxy-(2-substituted)-1,3,4-thia/oxadiazolo[2,3-b] pyrimidin-5-ones 3 and 6 and 5-amino-(2-substituted)-1,3,4-thia/oxadiazolo[2,3- b]pyrimidin-7-ones 4 and 7 have been synthesised from the synthon 2-amino-(5-substituted)-1,3,4-thia/oxadiazoles 1 and diethyl ethoxymethylenemalonate and ethyl cyanoacetate respectively. The molluscicidal activity of few title compounds have been evaluated against snail Lymnaea accuminata.

Life Sciences

Journal of the Indian Chemical Society

Synthesis and molluscicidal activity of 6-carboethoxy-(2-substituted)-1,3, 4-thia/oxadiazolo[2,3-b]pyrimidin-5-ones and 5-amino-(2-substituted)-1,3,4-thia/ oxadiazolo[2,3-b]pyrimidin-7-ones

A study was conducted during 2000-2003 to study segregation pattern of 4 pyramided resistance genes against bacterial blight caused by Xanthomonas oryzae pv oryzae in 'IRBB 60' in crosses involving 3 susceptible basmati quality genotypes ('Pusa Basmati 1', 'Pusa 1121' and 'Pusa 1387') of rice (Oryza sativa L.). All the basmati quality genotypes were found susceptible to bacterial blight. Three genes, Xa 4, xa 13 and Xa 21 were found resistant, while xa 5 showed susceptible reaction. Genetic analysis of 'IRBB 60' indicated 2 dominant and 1 recessive gene controlling resistance against bacterial blight in the cross 'Pusa Basmati 1' x 'IRBB 60' and 'Pusa 1121' x 'IRBB 60'. Deviation from expected segregation was observed in 'Pusa 1387' x 'IRBB 60' cross that may be owing to residual level of resistance or epistatic interaction. From the segregating generations, 32 high-quality, high resistance lines were identified that possessed high linear kernel elongation and length/ breadth ratio.

Indian Journal of Agricultural Sciences

Genetic analysis of pyramided genes for resistance to bacterial blight (Xanthomonas oryzae pv oryzae) and development of resistant lines of basmati rice (Oryza sativa)