Probing Internal Stress and Crystallinity in Wet Foam via Raman Spectroscopy

In this article, we correlate the internal stress and the characteristics of a vibrational mode in wet foam. Using microscope images, we estimate the average size of the bubbles in wet foam, at specific time intervals, over a duration of twenty four hours. Raman spectra are also recorded at the same time intervals, over the same time frame. We show that the internal stress, originated from the macroscopic structural change of foam with ageing, can be related to the observed Raman shift of the low frequency methylene rocking mode of the constituent surfactant molecules in foam. In this report we also show the capability of the Raman spectroscopy to reveal the crystallinity in foamy materials, when studied for a longer period of time.Comment: 16 pages, 7 figure

Heat and mass transfer on MHD flow through a porous medium over a stretching surface with heat source

An attempt has been made to study the heat and mass transfer effect on the flow over a stretching sheet in the presence of a heat source. The novelty of the present study is to consider the span wise variation of magnetic field strength, heat source and heat flux. It is also considered the effect of viscous dissipation. The method of solution involves similarity transformation which leads to an exact solution of velocity field. The coupled non-linear and non homogeneous heat equation has been solved by applying Kummer’s function. The non-homogeneity of the heat equation is contributed by the consideration of viscous dissipative energy. KYEWORDS: Heat source, Viscous dissipation, Porous medium, Kummer’s function

Assessment of heavy metals in the surrounding soils and their bioconcentrations in few plants near Kathajodi river, Odisha, India

The present study was carried out mainly concentrate on assessment of heavy metal in the surrounding soils and their bioconcentration in the different plants near Kathajodi River. Soil and plant samples were collected along the Kathajodi river, Odisha, India. It was found that the dominance of heavy metals follows a decreasing order. The metal concentrations measured in soil at all location generally decreased in the order; Fe > Mn > Ni> Pb> Cu> Zn> Cd. Highest heavy metal concentration in river bank soil Cd (0.72±0.05 mgkg-1); Ni (3.85±0.15 mgkg-1); Cu (1.66±0.15 mgkg-1); Zn (1.54±0.16 mgkg-1); Pb (4.11±0.14 mgkg-1); Fe (142.0±1.16 mgkg-1); Mn (37.30±1.16 mgkg-1) at different site . Among all the grass species I. laxum has the higher affinity for the accumulation of Cd (0.85±0.05) followed by Zn, Pb and Cu. This study indicates that bio concentration of heavy metals in the study area show preferential Cd uptake in the plants followed by Zn, Pb and it may lead to accumulates in the exposed plant part posing risk along the food chain. This calls for immediate action to be implemented to carry out necessary environment mitigation measures for the river as it can be attributed the discharge of untreated domestic waste and effluents in the river

Formulation and in vitro Evaluation of Eudragit® Microspheres of Stavudine

Purpose: The aim of this study was to formulate and evaluate microencapsulated controlled release preparations of a highly water-soluble drug, stavudine, using Copolymers synthesized from acrylic and methacrylic acid esters (Eudragit RS 100 and RL 100) as the retardant material. . Methods: Microspheres were prepared by solvent evaporation method using an acetone / liquid paraffin system. Magnesium stearate was used as the droplet stabilizer and n-hexane was added to harden the microspheres. The prepared microspheres were characterized for their micromeritic properties and drug loading, as well by fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, x-ray powder diffractometry and scanning electron microscopy. The in vitro release studies were performed in pH 6.8, phosphate buffer. Results: The prepared microspheres were white, free flowing and spherical in shape. The drug-loaded microspheres showed 67-91% of entrapment and release was extended upto 6 to 8 h. The infrared spectra and differential scanning calorimetry thermographs showed stable character of stavudine in the drug-loaded microspheres and revealed the absence of drug-polymer interactions. X-ray diffraction patterns showed that there was decrease in crystallinity of the drug. Scanning electron microscopy study revealed that the microspheres were spherical and porous in nature. Conclusion: The best-fit release kinetics was achieved with Higuchi plot followed by zero order and First order. The release of stavudine was influenced by the drug to polymer ratio and particle size & was found to be diffusion controlled. Keywords: Stavudine, Eudragit, microspheres, controlled release, polymethacrylate > Tropical Journal of Pharmaceutical Research Vol. 4 (1) 2005: pp. 369-37

Statistical Assessment of Long-term Shoreline Changes along the Odisha Coast

1990-1998Odisha, a coastal state on eastern seaboard of India possesses a ~450 km long coastline vulnerable to a multitude of natural and anthropogenic threats. The present study reports a systematic assessment of rates of shoreline change over a period of 25 years from 1990- 2015, using Landsat 5 and 8 series of (Thematic Mapper and Operational Land Imager) satellite images. An analysis of rate of shoreline change was carried out along select regions of Odisha coast using Digital Shoreline Analysis System (DSAS). Linear Regression Method (LRR) was used to estimate net shoreline change at sub decade time scale and End Point Rate (EPR) to estimate net shoreline change rate in between two consecutive years. The highest erosion with a coastline length of 63 km was observed between Rajnagar (around Satabhaya beach) and Mahakalapara (near to Hukitola beach) block of Kendrapara district and between Ersama (around Paradeep port) and Balikuda blocks (northern parts of Devi River mouth) of Jagatsinghpur coastal district. The result suggest that both EPR and LRR techniques were used to estimate shoreline change rate and the similar result of erosion by both EPR and LRR technique indicated weaker cyclic trend in erosion

Dynamics of a metastable state nonlinearly coupled to a heat bath driven by an external noise

Based on a system-reservoir model, where the system is nonlinearly coupled to a heat bath and the heat bath is modulated by an external stationary Gaussian noise, we derive the generalized Langevin equation with space dependent friction and multiplicative noise and construct the corresponding Fokker-Planck equation, valid for short correlation time, with space dependent diffusion coefficient to study the escape rate from a metastable state in the moderate to large damping regime. By considering the dynamics in a model cubic potential we analyze the result numerically which are in good agreement with the theoretical prediction. It has been shown numerically that the enhancement of rate is possible by properly tuning the correlation time of the external noise.Comment: 13 pages, 5 figures, Revtex4. To appear in Physical Review