Application of PMR Spectroscopy in Pharmaceutical Analysis Assay of Furosemide

An analytical method is described for the analysis of furosemide, [4-chloro-2-furfurylamino-5-sulfamoylbenzoic acid], using PMR. The procedure reported in this study is simple, rapid and gives accurate results 98.19 ± 1.34% and 99.23 ± 0.88% for furosemide ampoules and tablets respectively. Furthermore, the PMR spectrum obtained provides a mean for qualitative identification of the drug and checking its purity.     

Ethyl 3‐[1‐(5,5‐dimethyl‐2‐oxo‐1,3,2‐dioxaphosphorin‐2‐yl)propan‐2‐ylidene]carbazate: a combined X‐ray and density functional theory (DFT) study

In the title compound, C₁₁H₂₁N₂O₅P, one of the two carbazate N atoms is involved in the C=N double bond and the H atom of the second N atom is engaged in an intramolecular hydrogen bond with an O atom from the dimethylphosphorin‐2‐yl group, which is in an uncommon cis position with respect to the carbamate group. The cohesion of the crystal structure is also reinforced by weak intermolecular hydrogen bonds. Density functional theory (DFT) calculations at the B3LYP/6‐311++g(2d,2p) level revealed the lowest energy structure to have a Z configuration at the C=N bond, which is consistent with the configuration found in the X‐ray crystal structure, as well as a less stable E counterpart which lies 2.0 kcal mol⁻¹ higher in potential energy. Correlations between the experimental and computational studies are discussed.     

Characterization of catechol 1,2-dioxygenase from cell extracts of <Emphasis Type="Italic">Sphingomonas xenophaga</Emphasis> QYY

Sphingomonas xenophaga QYY, capable of growing significantly on more than ten kinds of aromatic compounds as sole carbon source, was used to study characterization of catechol 1,2-dioxygenase (C12O) in cell extracts. Characterization of the crude C12O showed that the maximum activity was obtained at 40–70°C and pH 7.8–8.8. Metal ions had different influences on the activity of crude C12O. It was suggested that strain QYY possessed an inducible and ferric-dependent C12O. Kinetic studies showed that the value of V _max and K _m was 0.25 μmol catechol/L/mg protein/min and 52.85 μmol/L, respectively. In addition, the partial purification of C12O was achieved by a HiTrap Q Sepharose column chromatography. Supported by the National Natural Science Foundation of China (Grant No. 50608011) and the 39th Postdoctoral Funds of China (Grant No. 20060390983)     

Functionalization of gold and carbon nanostructured materials using gamma-ray irradiation

Gold nanoparticles were successfully attached to the surface sites of carbon nanotubes (CNT). Both nanostructured materials were functionalized by λ-ray irradiation without chemical treatments for creating active sites. UV–visible absorption spectra of the un-irradiated and gamma ray-irradiated nanomaterials are also studied. The absorption spectrum of the irradiated CNT shows a new strong peak located at 700 nm, which might act as the active site on the surface of CNT, the result being an attachment of gold nanoparticles. This approach provides an efficient method to attach other nanostructures to carbon nanotubes for using them in different applications such as medicine and synthesis of catalytic materials.     

Thermal degradation of a reactive flame retardant based on cyclotriphosphazene and its blend with DGEBA epoxy resin

Hexaglycidyl cyclotriphosphazene (HGCP) was synthesized, and characterized by FTIR, ³¹P, ¹H, and ¹³C-NMR. This compound was used as a reactive flame retardant to blend with commercial epoxy resin DGEBA (Diglycidyl ether of bisphenol A). Its effect on the DGEBA decomposition pathways was characterized by studying both gas and solid phases produced during thermogravimetric analysis (TGA). The gases evolved during TGA in air were studied by means of thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR), while the solid residues were analysed by FTIR and scanning electron microscopy (SEM). The results showed that HGCP presents a good dispersion in DGEBA, and the blend thermoset with 4,4′-methylene-dianiline (MDA) curing agent leads to a significant improvement of the thermal stability at elevated temperature with higher char yields compared with pure DGEBA thermoset with the same curing agent. Improvement has also been observed in the fire behaviour of blend sample.     

Anticipating stochastic differential systems with memory

This article establishes existence and uniqueness of solutions to two classes of stochastic systems with finite memory subject to anticipating initial conditions which are sufficiently smooth in the Malliavin sense. The two classes are semilinear stochastic functional differential equations (sfdes) and fully nonlinear sfdes with a sublinear drift term. For the semilinear case, we use Malliavin calculus techniques, existence of the stochastic semiflow and an infinite-dimensional substitution theorem. For the fully nonlinear case, we employ an anticipating version of the Itô–Ventzell formula due to Ocone and Pardoux [D. Ocone, E. Pardoux, A generalized Itô–Ventzell formula. Application to a class of anticipating stochastic differential equations, Annales de l’Institut Henri Poincaré. Probabilité s et Statistiques 25 (1) (1989) 39–71]. In both cases, the use of Malliavin calculus techniques is necessitated by the infinite dimensionality of the initial condition.     

A new isoflavone glycoside from the aerial parts of <Emphasis Type="Italic">Retama sphaerocarpa</Emphasis>

A new isoflavone glycoside, genistein 7-O-xylosyl 8-C-glucoside (1), was isolated from the leaves of Retama sphaerocarpa. Its structure was elucidated by spectroscopic methods.     

Insight into the electronic,optical, thermodynamic,and thermoelectric properties of novel chalcogenides: An ab initio study

Ternary chalcogenides with direct band gaps are remarkable for being used in many optoelectronic applications. We investigated for structural, electronic, optical, and transport characteristics of new Ba₂CdCh₃ (Ch = S, Se, Te) semiconductors using the full-potential linearized augmented plane wave (FP-LAPW) approach. The band structures of these compounds confirm a direct type of band gap. The phonon dispersion plots along with the predicted negative formation energies suggest these compounds to be thermodynamically stable. Additionally, important optical characteristics were computed and thoroughly explained. The different ELF spectra were calculated in which strong peak correlate precisely with plasma resonance. Moreover, we also explored the thermodynamic characteristics of the ternary systems by employing the quasi-harmonic Debye model. These compounds were also suitable for thermoelectric applications based on the detailed discussion of the computed significant thermoelectric properties. In general, the advancement of various and promising semiconducting devices and their applications will be supported by the present study.