Morphological evolution of (NH4)(0.5)V2O5·mH2O fibers into belts, triangles, and rings.

In this contribution, single-crystalline (NH(4))(0.5)V(2)O(5)·mH(2)O xerogels made of belts, rings, triangles, and ovals have been synthesized using a surfactant-free hydrothermal method. The analytical techniques of scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), high-resolution TEM (HRTEM), and selected area electron diffraction (SAED) have been used to characterize the morphology, composition, and structure of the as-prepared products. On the basis of SEM and TEM observations, we suggested that the as-prepared (NH(4))(0.5)V(2)O(5)·mH(2)O rings, triangles, and ovals have been formed by connecting two ends of the vanadium oxide sheet made of edge and corner sharing VO(5) square pyramids. The as-prepared (NH(4))(0.5)V(2)O(5)·mH(2)O nanobelts are up to several hundreds of micrometers long, 402-551 nm wide, and 235-305 nm thick. The thickness and width of the rings are respectively ∼454 nm and ∼1 µm. Triangles with three unequal sides having a thickness of ∼143 nm and a width of ∼1 µm were also formed. The crystalline orthorhombic phase of shcherbianite V(2)O(5) was obtained on calcination of (NH(4))(0.5)V(2)O(5)·mH(2)O at 350 °C for 2 h. The SEM image of this V(2)O(5) product retains the parent morphology of the preheated compound. A possible reaction mechanism and the growth process involved in the formation of belts/rings/triangles and ovallike microstructures are discussed.

Spectroscopic studies and life time measurements of binding of a bioactive compound to bovine serum albumin and the effects of common ions and other drugs on binding.

The mechanism of binding of anti-inflammatory drug, nimesulide (NIM) with bovine serum albumin (BSA) was investigated by fluorescence, absorption, circular dichroism (CD) and lifetime measurements under simulative physiological conditions. The analysis of fluorescence data indicated the presence of both dynamic and static quenching mechanism in the binding. Various binding parameters have been evaluated. The CD spectral data revealed the decrease in alpha-helical content of BSA from 70.9% (in free BSA) to 42.03% (in bound form) thereby indicating the conformational change in BSA upon binding. The binding of NIM to BSA was also confirmed by absorption spectra. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r between the donor (BSA) and acceptor (NIM) was found to be 2.17 nm. The association constants of NIM-BSA decreased in presence of the common ions and other drugs thereby indicating the availability of higher concentration of free drug (NIM) in plasma.