α-Fe2O3@carbon core–shell nanostructure for luminescent upconversion and photocatalytic degradation of methyl orange

Research on Chemical Intermediates - The unique characteristics of metal–organic frameworks such as structural tunability, high surface area, low density, and tailored porosity have made this...     

Communication maps computed for homodimeric hemoglobin: computational study of water-mediated energy transport in proteins

Frequency-resolved communication maps provide a coarse-grained picture of energy transport in nanoscale systems. We calculate communication maps for homodimeric hemoglobin from Scapharca inaequivalvis and sample them to elucidate energy transfer pathways between the binding sites and other parts of the protein with focus on the role of the cluster of water molecules at the interface between the globules. We complement analysis of communication maps with molecular simulations of energy flow. Both approaches reveal that excess energy in one heme flows mainly to regions of the interface where early hydrogen bond rearrangements occur in the allosteric transition. In particular, energy is carried disproportionately by the water molecules, consistent with the larger thermal conductivity of water compared to proteins.     

Crystal and Molecular Structure of Ethyl 2-[（4-Hydroxy-phenyl）hydrazono]-3-oxobutanoate

The title compound,C 12 N 2 O 4 H 14 (M r=250.3),crystallizes in triclinic P1 space group with a=7.7709(9),b=8.7534(11),c=9.6958(12),α=77.103(2),β=80.496(2),γ=86.726(2)o,V=633.9(1) 3,Z=2,F(000)=264,D c=1.311 Mg/m 3,μ(MoKα)=0.1 mm-1,the final R=0.056,and wR=0.15 for 2239 observed reflections (I > 2σ(Ⅰ)).The molecules in the crystal are linked through O-H···O type of hydrogen bonding interaction forming an infinite chainlike structure.The phenylhydrazone ring and oxobutanoate groups are almost planar.The keto hydrazo group adopts a Z-configuration in the molecule and the torsion angle is-177.6(2)°.     

Development of yttria-doped thoria solid electrolyte for use in liquid sodium systems

Electrolytic grade yttria-doped thoria (YDT) was synthesized by a novel combustion method. Sintering studies were carried out with polyvinyl alcohol as binder or ZnO as sintering aid to obtain high-density product. The sintering temperature has been optimized as 1,923 K. The results showed that when ZnO was used and sintered at 1,923 K, high-density YDT pellets were obtained, which met the required helium leak rate of the order of ∼10⁻⁹ std. l/s. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006     

Design and development of chemical ontologies for reaction representation

This paper describes the development of chemical ontologies applied to the representation of organic chemical reactions. The ontologies are built using the methodology known as methontology. The hierarchically structured set of terms describing the subdomains, namely, organic reactions, organic compounds, and reagents, are constructed into individual ontologies. The ontologies consist of about 200 concepts and around 125 individuals. A set of binary relations is defined in order to integrate the ontologies with applications. The ontologies are implemented as an XML application with a set of vocabulary describing the domain knowledge. This paper also features an easy-to-use chemical ontological support system (COSS) intended to represent organic chemical reactions automatically. As a model application, the automatic representation of aliphatic nucleophilic substitution reactions is demonstrated using COSS. The paper also describes a keyword-based search system whose functionality is backed with COSS.     

Nonlinear molecular deformations and solitons in a nematic liquid crystal

We studied nonlinear molecular deformations in a nematic liquid crystal with homeotropically aligned molecules and hard boundaries. As the basic dynamical equation for the director axis of the liquid crystal resembles the Landau-Lifshitz equation representing spin dynamics in a one dimensional classical continuum isotropic Heisenberg ferromagnetic spin chain, we invoke here the space curve formalism and the stereographic projection technique used in the case of the Heisenberg spin chain. Under space curve mapping, the director dynamics with elastic deformation is found to be governed by a perturbed nonlinear Schrödinger equation. A multiple-scale perturbation analysis brings out perturbed solitons to represent molecular deformations in the nematic liquid crystal. However, when a constant electric field is applied, the director dynamics is expressed under stereographic projection and the molecular deformations are found to be governed by periodic and localized static planar director configurations. A linear stability analysis on the static planar configurations shows that the system exhibits stable deformations.     

Soliton-like molecular deformations in a nematic liquid crystal film

We study the nature of molecular deformations in a nematic liquid crystal film with elastic energy under homeotropic boundary conditions. The deformation in terms of splay, twist and bend fields of the director axis is found to be governed by the completely integrable Davey-Stewartson-I (DS-I) equation in (2+1) dimensions. Using the line soliton and breather solutions of the DS-I equation, the director axis is constructed, the components of which exhibit damped spatial oscillations. However, the splay and bend fields of the director axis exhibit localized structures of deformation.     

Electronic structure and vibrational spectra of X20H20 (X=C, Si, Ge, Sn): A theoretical study

Optimized geometries, HOMO–LUMO gaps, vertical ionization potentials and electron affinities are obtained using HF, and B3LYP methods with 6-311G** basis set for C₂₀H₂₀, Si₂₀H₂₀ and Ge₂₀H₂₀. For germanium and tin analogues, B3LYP calculations are performed with LANL2DZ effective core potential. Electron correlation is included by doing MP2 calculation. The harmonic frequencies of all the compounds are obtained using B3LYP with 6-311G** and/or LANL2DZ basis sets. The force field and vibrational spectra are analyzed and 74 symmetry unique non-redundant local force constants are evaluated. Probable assignments are proposed for all the fundamentals based on the potential energy distribution.     

Substituent effects on carbon-13 NMR chemical shifts of side chain carbonyl carbons of 4-substituted 1-naphthamides

Substituent induced¹³C NMR chemical shifts of side chain carbonyl carbons of several 4-substituted 1-naphthamides have been measured in DMSO-d ₆ solvent. Analysis of the substituent induced chemical shifts by the DSP equation gave the regression equation. Both {ie207-1} and {ie207-2} values were negative. The negative sign on {ie207-3} term indicates the operation of a reverse substituent effect and that π-polarisation is the important mechanism for the transmission of substituent effects by inductive effect. Theperi-hydrogen interaction in naphthamides forces the amide group out of the plane of the naphthalene ring.