Theoretical and experimental analysis of iron-exchanged X-zeolite catalyst for SI engine emission control

The fuel economy potential of lean-burn gasoline engines can be utilized without any adverse effect on the environment, only if a suitable catalytic system for converting NO_x in an oxidizing atmosphere is available. Selective catalytic reduction of NO_x over metal-exchanged zeolite can be one of the solutions for reducing NO_x in automobile exhaust containing excess oxygen. Iron-exchanged X-zeolite catalyst (Fe–X) has been developed and tested in the exhaust of an actual SI engine over a wide range of air–fuel ratio, space velocity (SV) and catalyst temperature. Maximum conversion efficiencies of 55.8% and 57.4% were recorded for NO_x and CO, respectively. The catalyst also maintains its high performance through a wide range of temperatures. A mathematical model has been developed as well for predicting the performance of the catalytic converter containing Fe–X catalyst and the numerical solutions are presented. The predicted results agree well with the experimental results and are within the experimental uncertainty limits. The absolute average deviations are found to be within 6% and 5% of the predicted conversion efficiencies for NO_x and CO, respectively.     

Pseudokobusine

The title compound, hetisan-6,11β,15β-triol, C₂₀H₂₇NO₃, is a hetisane-type diterpenoid alkaloid. It consists of six six-membered rings and two five-membered rings. The fused-ring system contains three chair, two boat, one distorted boat and two envelope conformations. Intramolecular and intermolecular hydrogen bonds are present between the O atoms, with O⃛O separations of 3.006 (3) and 2.743 (3) Å, as well as an O⃛N intermolecular interaction of 2.887 (3) Å.     

Stability,structural properties,and dissociation pathways of silylidyne‐amines RSiN and silylidyne‐phosphanes RSiP (R = F,Cl)

Stability, structural properties, and dissociation pathways of silylidyne‐amines FSiN, ClSiN, their isomers, and silylidyne‐phosphanes FSiP and ClSiP have been studied in detail using ab initio MP2, CCSD, and CCSD(T) and density functional B3LYP methods. After dissociation of FSiN, ClSiN, FSiP, and ClSiP, the fragmented atoms have been considered to be either in their ground state or in their metastable state in various dissociation channels. The dissociation energy for various dissociation pathways has been compared and interesting results have been obtained for the dissociation channels where the fragmented atoms are in their metastable states. The structure properties of these molecules agree well with the theoretical results wherever available. The NBO atomic charges of these molecules have been analyzed. The isomerization energy has been compared with existing theoretical data. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Group actions on graphs related to Krishnan-Sunder subfactors

We describe the principal graphs of the subfactors studied by Krishnan and Sunder in terms of group actions on Cayley-type graphs. This leads to the construction of a tower of tree algebras, for every positive integer , which are symmetries of the Krishnan-Sunder subfactors of index . Using our theory, we prove that the principal graph of the irreducible infinite depth subfactor of index 9 constructed by Krishnan and Sunder is not a tree, contrary to their expectations. We also show that the principal graphs of the Krishnan-Sunder subfactors of index 4 are the affine A and D Coxeter graphs.

     

Quantum dynamics of a system of coupled nonlinear oscillators: Spectral and information entropy‐based analysis

The quantum dynamics of the evolution of a system of a few coupled nonlinear oscillators is studied. The spectral entropy and the quantal information entropy, as well as their correlation functions, are computed and used to identify distinctive phases of the evolution. The two entropy functions lead to similar conclusions. It appears that adiabatic switching of the nonlinear interaction does not affect the nature of the short time dynamics but affects the dynamics over intermediate time scales. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Studies on addition polymerization in mixed solvent system. Part I. Chain transfer of water in polymerization of methyl methacrylate

The role of water as a chain-transfer agent in addition polymerization of methyl methacrylate and acrylamide in a mixed solvent system was studied. Water does not have any transfer with the growing polymer radical. The degree of polymerization is found to increase with increasing water concentration. This is probably due to a reduced termination rate resulting from coiling of the polymer chain in the presence of a nonsolvent like water.     

Enantioselective synthesis of pantolactone analogues from an ephedrine-derived morpholine-dione

An efficient enantioselective synthesis of β,β-dialkyl α-hydroxy γ-butyrolactones, analogues of pantolactone, has been developed employing a stereoselective Prins reaction of chiral alkylidene morpholinones, as the key step. Enantioselective synthesis of a naturally occurring pantolactone homologue and a spiro analogue of pantolactone was achieved with this protocol.     

Resistance to induction of micronuclei,chromosomal aberrations and apoptosis by <Superscript>60</Superscript>Co gamma-ray in a cell strain M5, derived from Chinese hamster V79 cells

The paper aims to investigate cytogenetic and apoptotic responses of γ-irradiation in a radio-resistant cell strain designated as M5. Induced micronuclei, chromosomal aberrations, nuclear fragmentation and nucleosomal ladders by γ-irradiation were less at equal doses in M5 cells in comparison with that obtained in the parental Chinese hamster V79 cells. However, at equal survival, there were no differences in the end points studied. Results indicate that the residual damages that lead to reproductive cell death also resulted in the cytogenetic and apoptotic responses. We speculate that the repair efficiency in M5 cells was more efficient and increased DNA repair could be the cause of radiation resistance observed in M5 cells.     

Extraction and chemical investigation of Kulthi (Macrotylona uniflorus,Lam.) seed protein

Studies have been carried out on the protein solubility profile of Kulthi (Macrotylona uniflorus, Lam.) seed in aqueous solution over various pHs and at different concentrations of NaCl, Na₂SO₃, CaCl₂, and MgCl₂ at pH 8.0. Amino acid analysis of isolated protein identified 17 amino acids, 9 of which are essential. Gel-permeation chromatography on Sephadex G-200 revealed the presence of seven components in the protein fraction. Their molecular weights were determined by two comparable standard methods. Extractable Kulthi seed proteins in salt solutions were separated electrophoretically into eight fractions whose molecular weights were found to be 186,200, 131,800, 108,400, 91,200, 53,700, 44,700, 38,000, and 27,500.     

Spectrophotometric determination of EDTA

Both iron(III) and its EDTA complex in 0-1N H(2)SO(4) medium absorb in the ultraviolet region of the spectrum, with absorption maxima at 305 and 258 nm respectively. EDTA can thus be determined by addition of excess of Fe(III) and measurement of the absorbance at the two wavelengths. An EDTA concentration as low as 10(-6)M can be determined with a fair degree of accuracy. The method is free from interferences from most common metal ions, and is simple and rapid.