Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.     

Enantioselective synthesis of (R)- and (S)-N-Boc-morpholine-2-carboxylic acids by enzyme-catalyzed kinetic resolution: application to the synthesis of reboxetine analogs

The (R)- and (S)-N-Boc-morpholine-2-carboxylic acids 9 and 10 were prepared using an enantioselective synthesis employing a highly selective enzyme-catalyzed kinetic resolution of racemic n-butyl 4-benzylmorpholine-2-carboxylate (11) as the key step. Acids 9 and 10 were then converted efficiently and stereoselectively to reboxetine analogs 3 and 4.     

Comparison of simplex algorithms

A new modification of the super-modified simplex algorithm is described. The performance of this algorithm is compared with that of the super-modified simplex algorithm and the Nelder-Mead, or modified, simplex algorithm, using both mathematical functions and experimental optimization of an inductively coupled plasma spectrometer. The modification added to the super-modified simplex algorithm increases its speed and accuracy over the original super-modified algorithm.     

Nano-dimensions for the pyrogallol[4]arene cavity

The cup-like cavity of pyrogallol[4]arenes has been deepened by the addition of four hydrogen bonded bipyridine molecules to the upper-rim of the calixarene, enabling the extended cup-like molecules to stack inside one another and consequently trap and completely enshroud a single guest molecule within the 250 angstroms3 cavitand formed between two of these stacked "nano-cups".     

Solvent-free, direct synthesis of supramolecular nano-capsules

The single step direct synthesis of pyrogallol[4]arene via a solvent free protocol yields the pure product as a self-assembled nano-capsule, comprised of six macrocyclic building blocks.     

A theoretical investigation of charge transfer in several substituted acridinium ions

We present calculations for various properties of the ground and excited states of several arylamine-substituted acridinium ion systems that have been studied experimentally. Using ab initio and semiempirical quantum mechanical methods together with the generalized Mulliken-Hush (GMH) model, we examine the excitation energies, dipole moment shifts, and electronic coupling elements for the vertical charge shift (CSh) processes in these systems. We also examine solvent effects on these properties using a dielectric continuum reaction field model. The results are in generally good agreement with available experimental results and indicate that there is strong electronic coupling in these systems over a wide range of torsional angles. Nevetheless, the initial and final cationic states remain reasonably well-localized over this range, and thus TICT state formation is unlikely in these systems. Finally, a version of the GMH model based on Koopmans' Theorem is developed and found to yield coupling elements generally within a factor of 2 of the many-electron GMH for a sample acridinium system, but with overestimated adiabatic and diabatic dipole moment differences.     

A versatile new torch for inductively coupled plasma spectrometry

A modified torch for optical emission spectrometry with an inductively coupled plasma source is described. The demountable torch incorporates a flared intermediate tube, a capillary injector tube and interchangeable jets at the gas inlets. The optimised performance of the torch is compared with that of a conventional torch. The new torch can be operated over a wide range of gas flows and shows considerable promise in work with an argon-cooled plasma. The ability to operate at high or low gas flow rates, and the possibility of interchanging tubes and jets easily illustrate the versatility of the new design.