Myeloperoxidase inhibitory and radical scavenging activities of flavones from Pterogyne nitens

Two new flavone glucosides, nitensosides A and B (1, 2), together with four known compounds, sorbifolin (3), sorbifolin 6-O-beta-glucopyranoside (4), pedalitin (5), and pedalitin 6-O-beta-glucopyranoside (6) were isolated from Pterogyne nitens. Their structures were elucidated from 1D and 2D NMR analysis, as well as by high resolution mass spectrometry. All the isolated flavones were evaluated for their myeloperoxidase (MPO) inhibitory activity. The most active compound, pedalitin, exhibited IC50 value of 3.75 nM on MPO. Additionally, the radical-scavenging capacity of flavones 1-6 was evaluated towards ABTS and DPPH radicals and compared to standard compounds quercetin and Trolox.     

Wax-impregnated carbon paste electrode modified with mercuric oxalate for the simultaneous determination of heavy metal ions in medicinal plants and Ayurvedic tablets.

A wax-impregnated carbon paste electrode with mercury oxalate as the bulk modifier is found to be suitable for the determination of heavy metal ions by differential pulse anodic stripping voltammetry. The contents of binder and modifier have been optimized, until they showed low background current and easy renewability. The bulk-modified electrode is applied for the simultaneous determination of Zn, Cd, Pb and Cu in medicinal plants and Ayurvedic tablets (Liv 52). The results obtained have been validated with HMDE and AAS and are found to be comparable.     

Layer ordering and faulting in (GaAs)n/(AlAs)n ultrashort-period superlattices

We report studies of (GaAs)(n)/(AlAs)(n) ultrashort-period superlattices using synchrotron x-ray scattering. In particular, we demonstrate that interfaces of these superlattices contain features on two different length scales: namely, random atomic mixture and ordered mesoscopic domains. Both features are asymmetric on the two interfaces (AlAs-on-GaAs and GaAs-on-AlAs) for n>2. Periodic compositional stacking faults, arising from the intrinsic nature of molecular-beam epitaxy, are found in the superlattices. In addition, the effect of growth interruption on the interfacial structure is discussed. The relevant scattering theory is developed to give excellent fits to the data.     

Bending Moment in Membrane Theory

A model of nonlinear membrane is proposed where the external loading induces a density of bending moments. The mathematical justification of this model is obtained through a 3D–2D dimension reduction via a Γ-convergence analysis taking into account the Cosserat vector field.     

The stability of barycentric interpolation at the Chebyshev points of the second kind

We present a new analysis of the stability of the first and second barycentric formulae for interpolation at the Chebyshev points of the second kind. Our theory shows that the second formula is more stable than previously thought and our experiments confirm its stability in practice.We also extend our current understanding regarding the accuracy problems of the first barycentric formula.