Resonant Raman of OH/OD vibrations and photoluminescence studies in LiTaO3 thin film

Resonant Raman spectra (RRS) of O-H and O-D vibration and libration modes, their combinations and higher harmonics have been observed in LiTaO3 polycrystalline thin films. RRS peaks are superimposed on photoluminescence (PL) spectrum. Monochromatic light from a xenon lamp is used as excitation source. PL spectrum shows two broad peaks, first near the band gap in UV (4.4-4.8eV) and another in the sub band gap region (< 4.0 eV). Band gap PL along with RRS peaks are reported for the first time. Photoluminescence excitation spectrum (PLE) shows a peak at 4.8 eV. Peak positions and full width at half maximum (FWHM) of RRS peaks depend upon the excitation energy. Dispersions of the fundamental and the third harmonic of the stretching mode of O-H with excitation energy are about 800 cm-1/eV and 2000 cm-1/eV respectively. This dispersion is much higher than reported in any other material.Comment: 20 page

Organoaxial volvulus of descending colon: a case report

“Colonic volvulus” refers to the twisting of colon, which most commonly involves sigmoid colon causing obstruction, ischemia and gangrene. But very rarely segment of descending colon can be involved. This is a case of 42 year old male with vomiting, abdomen pain and distension since one day, showing organoaxial volvulus of descending colon loop with a twist of mesentery

Dispersion of Resonant Raman Peaks of CO and OH in SnO2, Mo1-x FexO2 Thin Films and SiO2 bulk glass

Resonance Raman (RR) peaks of and stretching modes and their higher harmonics have been observed superimposed on photoluminescence (PL) spectrum of thin films. Commercial fluorine doped thin films deposited by sputtering on glass and thin films deposited on Si by laser ablation have been studied. The dispersions of CO and OH stretching RR modes are ~ 600 cm-1/eV and 800 cm-1 respectively. The dispersion of the third harmonic of CO stretching mode is ~ 2000 cm-1/eV. Similar dispersion of RR peak of stretching modes and higher harmonics superimposed on PL spectra has been observed in Mo1-xFexO2 thin films and SiO2 bulk glass. Large dispersion of RR peaks seems to be a common property of oxides with impurities of and .Comment: 13 pages including three figure

Antibacterial, Insecticidal and Free radical scavenging activity of methanol extract of Ziziphus rugosa Lam. (Rhamnaceae) fruit pericarp

Introduction: Ziziphus rugosa Lam. belongs to the family Rhamnaceae and is found chiefly in deciduous and semievergreen forest of Western Ghats. The present study was undertaken to determine antibacterial, insecticidal and free radical scavenging activity of methanol extract of Ziziphus rugosa Lam. fruit pericarp. Methods: The powdered fruit pericarp of Z. rugosa was extracted with methanol. Antibacterial activity of methanol extract was determined against Escherichia coli and Staphylococcus aureus by Agar well diffusion method. Free radical scavenging activity was determined using DPPH assay. The insecticidal activity of extract was tested against second instar larvae of Aedes aegypti. Results: The extract exhibited dose dependent inhibition of test bacteria. Among bacteria, E. coli was found to be more susceptible to extract than S. aureus. All the concentrations of extract produced over 50% mortality of larvae and the larvicidal effect was found to be dose dependent. The extract caused 100% mortality of larvae at concentration of 50 mg/ml. The extract exhibited concentration dependent radical scavenging activity with an IC 50 value of 61.88 µg/ml. The phytochemical analysis of extract showed the presence of alkaloids, saponins, flavonoids and glycosides. Conclusion: The extract, in suitable form, may be used to control bacterial diseases, free radical damage and arboviral diseases. The phytoconstituents present in the extract may be responsible for the tested biological efficacies of extract. Further studies on isolation of active constituents from the extract and their biological activity are under investigation

Effect of pinning and driving force on the metastability effects in weakly pinned superconductors and the determination of spinodal line pertaining to order-disorder transition

We explore the effect of varying drive on metastability features exhibited by the vortex matter in single crystals of 2H-NbSe$_2$ and CeRu$_2$ with varying degree of random pinning. An optimal balance between the pinning and driving force is needed to view the metastability effects in typically weakly pinned specimen of low temperature superconductors. As one uses samples with larger pinning in order to differentiate the response of different metastable vortex states, one encounters a new phenomena, viz., the second magnetization peak (SMP) anomaly prior to the PE. Interplay between the path dependence in the critical current density and the non-linearity in the electromagnetic response determine the metastability effects seen in first and the third harmonic response of the ac susceptibility across the temperature regions of the SMP and the PE. The limiting temperature above which metastability effects cease can be conveniently located in the third harmonic data, and the observed behavior can be rationalized within the Beans Critical State model. A vortex phase diagram showing the different vortex phases for a typically weakly pinned specimen has been constructed via the ac susceptibility data in a crystal of 2H-NbSe$_2$ which shows the SMP and the PE anomalies. The phase space of coexisting weaker and stronger pinned regions has been identified. It can be bifurcated into two parts, where the order and disorder dominate, respectively. The former part continuously connects to the reentrant disordered vortex phase pertaining to the small bundle pinning regime, where the vortices are far apart, interaction effects are weak and the polycrystalline form of flux line lattice prevails.Comment: Submitted to the Special Volume on Vortex State Studies, Pramana J. Phy