Simple and economical conversion of organic compounds with H2O2 catalyzed by ruthenium (III) chloride

Six aromatic aldehydes, two hydrocarbons, one cycloalcohol and one aromatic alcohol, viz. benzaldehyde, p‐chlorobenzaldehyde, cinnamaldehyde, 4‐methoxybenzaldehyde, o‐hydroxybenzaldehyde, 4‐hydroxy, 3‐methoxybenzaldehyde, anthracene, phenanthrene, cyclohexanol and benzyl alcohol dissolved in acetic acid, were oxidized in quantitative to moderate yields by 50% H₂O₂ in the presence of traces of RuCl₃ (substrate:catalyst ratio 85 400 to 387 500:1). Conditions for highest yields, under most economical conditions, were obtained. Higher catalyst concentrations decreased the yield. Oxidation in aromatic aldehydes is selective at aldehydic group only, and other groups remain unaffected. The extent of oxidation in phenanthrene depends on temperature or the relative amount of substrate or both. In this new, simple and economical method, which is environmentally safe and requires less time, oxocentered carboxylate species of ruthenium (III) probably catalyze the oxidation. Copyright © 2005 John Wiley & Sons, Ltd.     

Minkowskian geometry,convexity conditions and the parallel axiom

The problem of characterising Minkowskian spaces is an important problem of that branch of differential geometry in which spaces more general than the complete Riemann and Finsler spaces are studied axiomatically using synthetic geometric methods. The fundamental theorem in this field is the result that a Desarguesian straightG-space in which the parallel axiom holds and the spheres are convex is Minkowskian. However the question as to whether the hypothesis of the space being Desarguesian is necessary or not has remained unsolved for over forty years. It is therefore natural to investigate conditions stronger than the mere convexity of spheres. In this paper such geometric conditions derived from functions which measure the distance between lines and points on lines are studied. Besides characterising the Minkowskian spaces these investigations also bring out the interplay between the parallel axiom and the convexity and linearity conditions.     

Gold(I)-catalyzed unprecedented rearrangement reaction between 2-aminobenzaldehydes with propargyl amines: an expedient route to 3-aminoquinolines

Access to aminoquinolines: a gold(I)-catalyzed unprecedented rearrangement reaction between 2-aminobenzaldehydes with propargyl amine was studied. The study provided, for the first time, direct access to 3-aminoquinolines in one step starting from readily available starting materials. Elegantly designed experiments were employed to unravel the mechanism of this unprecedented rearrangement, which are corroborated by DFT calculations.     

Mineralized Synthetic Matrices as an Instructive Microenvironment for Osteogenic Differentiation of Human Mesenchymal Stem Cells

The effect of substrate‐mediated signals on osteogenic differentiation of hMSCs is studied using a synthetic bone‐like material comprising both organic and inorganic components that supports adhesion, spreading, and proliferation of hMSCs. hMSCs undergo osteogenic differentiation even in the absence of osteogenesis‐inducing supplements. They exhibit higher expressions of Runx2, BSP, and OCN compared to their matrix‐rigidity‐matched, non‐mineralized hydrogel counterparts. The mineralized‐hydrogel‐assisted osteogenic differentiation of hMSCs could be attributed to their exposure to high local concentrations of calcium and phosphate ions in conjunction with chemical and topological cues arising from the hydrogel‐bound calcium phosphate mineral layer.

     

Disturbance observer based sliding mode control of active suspension systems

In this paper, a novel scheme to reduce the acceleration of the sprung mass, used in combination with sliding mode control, is proposed. The proposed scheme estimates the effects of the uncertain, nonlinear spring and damper, load variation and the unknown road disturbance. The controller needs the states of sprung mass only, obviating the need to measure the states of the unsprung mass. The ultimate boundedness of the overall suspension system is proved. The efficacy of the method is verified through simulations for three different types of road profiles and load variation and the scheme is validated on an experimental setup. The results are compared with passive suspension system.     

Cyclotriphosphazene Ring as a Platform for Multiporphyrin Assemblies

Rings around a ring : The synthesis, characterization, material properties and biological studies of novel hexakis porphyrinato cyclotriphosphazene systems (see scheme) and their metal derivatives are described.

     

Generalized inverses and operator equations

In this paper we obtain conditions under which the operator equations of the types AX = C and $\text{AXA}{}^1\text{= C}$ have hermitian and nonnegative definite solutions; here A is assumed to be relatively invertible. In addition we obtain some properties of generalized inverses of operators. Lastly we pose some conjectures; one of them is that the set of all nonzero relatively invertible operators is not connected.     

Influence of degeneracy on momentum relaxation times in semiconductors

We have studied the effect of degeneracy on momentum relaxation times under ohmic as well as non-ohmic conditions. We find that a proper momentum relaxation time, within the framework of the Boltzmann transport equation, can no longer be defined for isotropic but inelastic scattering when the carriers are hot whereas under ohmic conditions it can be defined and is appreciably altered by degeneracy. For elastic scattering the momentum relaxation time is found to be unaffected by degeneracy for both ohmic and non-ohmic regimes.     

Spectrophotometric determination of rhenium using 2-pyridyl thiourea

The reagent 2-pyridyl thiourea produces a reddish brown complex with rhenium in hydrochloric acid medium in the presence of tin(II) chloride. The complex shows absorption maxima at 405 nm, obeys Beer's law for a range of 1–16 ppm of rhenium. The sensitivity and molar absorptivity is found to be 0.0115g cm^–2 and 1.603×10⁴ 1 mol^–1 cm^–1 respectively showing an improvement over other sulphur-nitrogen bearing ligands. Composition found by Job's and mole ratio method, indicates that the complex contains metal and reagent in the ratio 12. Stability constant and stepwise formation constants of the complex have been evaluated by Harvey-Manning's method (logK _overall=8.825), Leden's method (logK _overall=8.3096), Rossotti-Rossotti's method (logK _overall=8.653) and Yatsimirskii's method (logK _overall=8.740). The relative error per 1% absolute photometric error is found to be 2.7%.