Ruthenium(III)-catalysed oxidation of thiocyanate by periodate in aqueous alkaline medium; autocatalysis in catalysis

The oxidation of thiocyanate by periodate has been studied in alkaline media. A micro quantity of Ru^III is sufficient to catalyse the reaction. The active catalytic species and oxidant in the reaction are understood to be [Ru(H₂O)₅OH]²⁺ and IO⁻ ₄. The autocatalysis exhibited by one of the products, cyanate, is attributed to adduct formation between cyanate and periodate. A composite mechanism and rate law are proposed. The reaction constants involved in the mechanism are evaluated. This revised version was published online in June 2006 with corrections to the Cover Date.     

BF3·Et2O and trifluoroacetic acid/triethyl amine-mediated synthesis of functionalized piperidines

A two-step short and efficient strategy for the synthesis of substituted piperidones and piperidines in high diastereoselectivity (only trans-configuration), by employing cascade type reaction using BF₃·Et₂O or by carrying out one pot deprotection of ^tBoc group followed by intramolecular aza-Michael addition of α,β-unsaturated beta keto esters has been developed. Using a similar strategy a short access to hydroxy pipecolic acid is also described. Very simple and rapid experimental procedures involving mild conditions and only one or two chromatographic purifications are the main features of the process.     

Synthesis,Crystal Structure and Spectroscopic Properties of an Oximato Bridged Cu(II) Dimer

Abstract  

Schiff-base condensation of a equimolar proportion of diacetyl-monoxime monohydrazone and 1-methylimidazole-2-carboxaldehyde in methanol gives rise to the imidazole azine, 3-(1-methylimidazol-2-yl)methylenehydrazonobutan-2-one oxime(HL). Reaction of 1:1 stoichiometric proportion of HL with copper(II)perchlorate hexahydrate in methanol yields a dimeric oximato bridged copper compound, [Cu₂L₂(H₂O)₂](ClO₄)₂ (1). The compound is characterized by C, H and N analyses, FT-IR, ESI–MS, conductivity measurement, UV–Vis spectra and X-ray single crystal diffraction. The title compound (1) crystallizes in the monoclinic space group P2₁/c with a = 6.8533 (8), b = 18.413 (2), c = 11.7399 (14) ?, β = 93.685 (2)°, V = 1478.4 (3) ?³ and Z = 2. The geometry around each copper center is distorted square pyramidal. The copper(II) dimer shows antiferromagnetic interaction mediated by symmetric disposition of oximato groups.     

A numerical investigation of energy dissipation with a shallow depth sloshing absorber

A liquid sloshing absorber consists of a container, partially filled with liquid. The absorber is attached to the structure to be controlled, and relies on the structure’s motion to excite the liquid. Consequently, a sloshing wave is produced at the liquid free surface within the absorber, possessing energy dissipative qualities. The behaviour of liquid sloshing absorbers has been well documented, although their use in structural control applications has attracted considerably less attention.     

Radiochemical methods of measurements of fission products yields

Techniques used for the measurement of independent and cumulative fission yields are reviewed in this article.     

Total synthesis of the alkaloid (−)-codonopsinine from l-xylose

The enantiopure total synthesis of (−)-codonopsinine is described from commercially available l-xylose in 20% overall yield. The key steps included Julia trans olefination and cascade epoxidation-cyclisation strategies.     

Electronic structure and optical absorption spectra of CdSe covered with ZnSe and ZnS epilayers

Using the first-principles methods we compute the electronic structure and the absorption spectra for a wurtzite CdSe (0001) slab covered with zincblende ZnSe and ZnS epilayers. For each structure we compute the DOS and the imaginary part of the dielectric function. We find that the semiconductor passivation shifts the ‘near Fermi-level’ states of the bare CdSe slab down to lower energy levels. The migration suggests the decrease of surface effects and energy loss. We observe the substantial reduction of the abnormal peaks in the absorption spectra of the bare CdSe slab, which seems to be a consequence of the DOS migration. This is consistent with the experimental results that a proper passivation enhance the luminescence efficiency. We also study the case that the epilayer surface is terminated with PH₃ and find the PH₃ passivation also reduces the surface state to some extent.     

E-R modeling and visualization of large mutual fund data

Existing visualization techniques used by mutual fund managers focus on the active portfolio management strategies. However, an important aspect of mutual funds is to visualize and understand the fund composition observed at specific points in time. Such a visualization will leverage the fund manager with the power to investigate and to capture forecasting differences and future performance. Our research here is to design a new visualization system that has an Entity-Relationship (E-R) model at the heart of the system and reveals not only the aggregate behavior of the mutual funds, but also the behavior of the mutual fund managers who manage these funds. We find some preliminary evidence that mutual funds in the world market represent a strong geographical pattern, and some potential niche markets are now extracted that stands out in the global scenario such as the returns from funds that belong to a specific country. For the analysis of security distribution, it helps to distinguish the most popular securities from other ordinary ones for an increased realization of profit. Also based on our experience with such huge world fund data to achieve a trade-off between time efficiency and graphics quality, we recommend the approach of splatting visualization, which indicates the influence of a particular security in a fund’s portfolio.