The mechanism of the sonochemical degradation of benzoic acid in aqueous solutions

The sonolytic degradation of benzoic acid in aqueous solution was investigated at an ultrasonic frequency of 355 kHz. The degradation rate was found to be dependent upon the solution pH and the surface activity of the solute. The degradation rate was favoured at a solution pH lower than the pK _a of benzoic acid. At pH < pK _a, HPLC, GC and ESMS analysis showed that benzoic acid could be degraded both inside the bubble by pyrolysis and at the bubble/solution interface by the reaction with OH radicals. At higher pH (> pK _a) benzoic acid could only react with OH radicals in the bulk solution. During the sonolytic degradation of benzoic acid, mono-hydroxy substituted intermediates were observed as initial products. Further OH radical attack on the mono-hydroxy intermediates led to the formation of di-hydroxy derivatives. Continuous hydroxylation of the intermediates led to ring opening followed by complete mineralization. Mineralization of benzoic acid occurred at a rate of < 40μM/h.     

Chemiluminescence as diagnostic tool in the development of gas turbines

To optimise the operation of gas turbine combustors with respect to emission, cycle efficiency and components lifetime, increased attention has to be attributed to diagnostic techniques and more flexible control schemes. Chemiluminescence is an obvious choice and a relatively easy and low cost option for such a diagnostic tool. Application examples include spectral analysis and light intensity scaling, temporal analysis studying flame dynamic effects and imaging techniques resolving spatial distribution of heat release zones, as well as combinations of the methods like phase matched imaging and tracking of ignition kernels using high speed imaging. Further fundamental work should be triggered on the nature for the excited species and their formation pathways as well as their connection to heat release and the NO _x formation processes.     

Structure–property correlations in lead silicate glasses and crystalline phases

Lead silicate glasses containing 40–65?mol% of PbO were prepared at two melt-quenching rates and characterized by X-ray diffraction, UV-Visible absorption spectroscopy, density, microhardness, thermo-mechanical analysis, differential scanning calorimetry and Raman scattering studies. On increasing the PbO concentration, density increases, glass transition temperature decreases and the optical absorption edge shifts towards longer wavelength. An intense optical absorption band was observed just below the absorption edge in glasses with 55?mol% and higher concentration of PbO. Dilatometric measurements show an unusual property that glasses do not show any abrupt increase in volume near the glass transition temperature but transform directly into the liquid state. Raman spectroscopy confirmed that the concentration of SiO₄ tetrahedra containing one or more NBOs increase with PbO mol%. Devitrification studies on lead silicate glasses found that samples with 40–45?mol% of PbO do not crystallize, whereas samples with higher PbO concentration produce multiple crystalline phases like PbSiO₃, Pb₃₃Si₂₄O₈₁, Pb₂SiO₄ and Pb₃Si₂O₇ on heat treatment.     

Parametric Excitation of Hybrid Modes in Multispecies Plasmas

Nonlinear decay of an electromagnetic wave into lower-hybrid and upper-hybrid wave in a plasma containing two types of ions and two temperature electrons has been analytically investigated. Hydrodynamical model of the plasma is used. Nonlinear dispersion relation and growth rates are calculated for parametric decay, modulational and filamentation instabilities. As an application of the investigation growth rates are calculated for typical parameters of both laboratory and space plasmas. Effect of addition of second species of electrons and ions is discussed.     

Study of cosurfactant effect on nanoemulsifying area and development of lercanidipine loaded (SNEDDS) self nanoemulsifying drug delivery system

The present study deals with the development and characterization of self-nanoemulsifying drug delivery system (SNEDDS) to improve the oral bioavailability of poorly soluble third generation calcium channel blocker lercanidipine (LER). Solubility of the LER was estimated in various oils, cosurfactants and surfactants which were grouped into two different combinations to construct pseudoternary phase diagrams. Various thermodynamic stability and dispersibility tests were performed on the formulations from phase diagram. After constructing phase diagram of two different combinations NL-I and NL-II, the effect of cosurfactants on the nanoemulsifying area was studied and the effect of number and length of hydrophobic alkyl chains of cosurfactant in its emulsification capacity was proved. Percentage transmittance, emulsification time, viscosity and droplet size analysis were used to characterize optimized formulations. The optimized formulation composed of Cremophor EL (45% wt/wt), (13.5% wt/wt) Caproyl 90 with (1.5% wt/wt) Transcutol® HP as per limits of inactive ingredients guidelines of FDA and Maisine oil (10% wt/wt). The mean droplet size in selected nanocarrier system was 20.01 nm. The in vitro dissolution profile of LER SNEDDS was found significant in comparison to the marketed LER (Zanidip) tablet and pure drug in pH 1.2, 4.5 and 6.8 buffers. Empty hard gelatin capsule shells were filled using Pfizer's Licap technology and charged on stability conditions of 30 °C/65% RH, 40 °C/65%RH and 50 °C/75% in glass bottles where no significant degradation (p > 0.05) was observed in 3 months. The results indicate that SNEDDS of LER, owing to nanosized, has potential to enhance the absorption of drug.     

Performance liquid chromatographic analysis of glipizide: application to in vitro and in vivo studies

This paper describes the validation of a sensitive, accurate, and reproducible method for the determination of a release profile of glipizide from controlled-release dosage forms. In this method, an in vitro dissolution profile of commercial controlled-release dosage forms is determined using a reversed-phase C(18) column, mobile phase (acetonitrile-buffer, 0.05 M KH(2)PO(4) adjusted to pH 3.5 with orthophosphoric acid), and UV detection at a wavelength of 275 nm. The method is validated for linearity, accuracy, precision, and detection and quantitation limits. The same method can be exploited to determine the plasma concentration of glipizide. The peak area versus plasma concentration is linear over the range of 12.5-1000 ng/mL and the detection limit was 5 ng/mL in plasma. The average accuracy was 99.90% with a relative standard deviation (RSD) of not more than 3%. Repeatability and reproducibility were found to be good with an RSD of less than 3%.     

Thermochemistry of some π-π charge transfer complexes formed between methylbenzene donors and π-electron acceptors

The heats of formation for- ^* charge transfer interactions have been computed from the charge transfer spectra of molecular complexes formed between methylbenzene donors and-electron acceptors.Miss Rajni Sachdeva and Anita Singla are grateful to I.C.A.R. (India) and C. S. I. R. (India), respectively, for financial assistance.     

Multifaceted Effects of Lycopene: A Boulevard to the Multitarget-Based Treatment for Cancer

Lycopene is a pigment belonging to the group of carotenoids and it is among the most carefully studied antioxidants found especially in fruit and vegetables. As a carotenoid, lycopene exerts beneficial effects on human health by protecting lipids, proteins, and DNA from damage by oxidation. Lycopene is a powerful oxygen inactivator in the singlet state. This is suggestive of the fact that lycopene harbors comparatively stronger antioxidant properties over other carotenoids normally present in plasma. Lycopene is also reported to hinder cancer cell proliferation. The uncontrolled, rapid division of cells is a characteristic of the metabolism of cancer cells. Evidently, lycopene causes a delay in the progression of the cell cycle, which explains its antitumor activity. Furthermore, lycopene can block cell transformation by reducing the loss of contact inhibition of cancer cells. This paper collects recent studies of scientific evidence that show the multiple beneficial properties of lycopene, which acts with different molecular and cellular mechanisms.