Sangita Dhara

Synthesis of oleic acid functionalized Fe3O4 magnetic nanoparticles and studying their interaction with tumor cells for potential hyperthermia applications.

In the present study, oleic acid (OA) functionalized Fe3O4 magnetic nanoparticles (MN) were synthesized following modified wet method of MN synthesis. The optimum amount of OA required for capping of MN and the amount of bound and unbound/free OA was determined by thermogravimetric analysis (TGA). Further, we have studied the effect of water molecules, associated with MN, on the variation in their induction heating ability under alternating current (AC) magnetic field conditions. We have employed a new approach to achieve dispersion of OA functionalized MN (MN-OA) in aqueous medium using sodium carbonate, which improves their biological applicability. Interactions amongst MN, OA and sodium carbonate were studied by Fourier transform infrared spectroscopy (FT-IR). Intracellular localization of MN-OA was studied in mouse fibrosarcoma cells (WEHI-164) by prussian blue staining and confocal laser scanning microscopy (CLSM) using nile blue A as a fluorescent probe. Results showed MN-OA to be interacting mainly with the cell membrane. Their hyperthermic killing ability was evaluated in WEHI-164 cells by trypan blue method. Cells treated with MN-OA in combination with induction heating showed decreased viability as compared to respective induction heating controls. These results were supported by altered cellular morphology after treatment of MN-OA in combination with induction heating. Further, the magnitude of apoptosis was found to be ~5 folds higher in cells treated with MN-OA in combination with induction heating as compared to untreated control. These results suggest the efficacy of MN-OA in killing of tumor cells by cellular hyperthermia.

Luminescence, lifetime, and quantum yield studies of redispersible Eu3+-doped GdPO4 crystalline nanoneedles: Core-shell and concentration effects

Crystalline nanoneedles of Eu3+-doped GdPO4 and Eu3+-doped GdPO4 covered with GdPO4 shell (core shell) have been prepared at relatively low temperature of 150 °C in ethylene glycol medium. From luminescence study, asymmetric ratio of Eu3+ emission at 612 nm (electric dipole transition) to 592 nm (magnetic dipole transition) is found to be less than one. Maximum luminescence was observed from the nanoparticles with Eu3+ concentration of 5 at. %. For a fixed concentration of Eu3+ doping, there is an improvement in emission intensity for core-shell nanoparticles compared to that for core. This has been attributed to effective removal of surface inhomogeneities around Eu3+ ions present on the surface of core as well as the passivation of inevitable surface states, defects or capping ligand (ethylene glycol) of core nanoparticles by bonding to the shell. Lifetime for D50 level of Eu3+ was found to increase three times for core-shell nanoparticles compared to that for core confirming the more Eu3+ ions with sym...

Galvanic reactions involving silver nanoparticles embedded in cation-exchange membrane.

Galvanic reactions of Hg(2+), Rh(3+), and AuCl(4)(-) ions with Ag nanoparticles positioned near the surface and throughout the matrix of host poly(perfluorosulfonic) acid membrane have been studied.

Preparation, characterization and thermal behavior of K2U4O13-Rb2U4O13 solid solutions

Abstract The preparation and characterization of (K1−xRbx)2U4O13 solid solutions has been studied for the x values in the range of 0 − 1. The solid solutions were prepared by heating K2U4O13 and Rb2U4O13 in required stoichiometry at about 600–700 ℃ for about 50 h in air atmosphere. The XRD patterns of the products suggest formation of the solid solutions in full composition range of Rb2U4O13 and K2U4O13. The cell volume of the crystal unit cell of solid solutions changes linearly with Rb atom % in (Rb + K) present in the solid solutions and follows Vegards law. The solid solutions when heated in Ar/He atmospheres at 900 ℃ produce corresponding low valent uranate solid solutions (K1−xRbx)2U4O12 or their mixtures.

Direct Multielemental Trace Determinations in Plutonium Samples by Total Reflection X-ray Fluorescence Spectrometry Using a Very Small Sample Amount

A simple, safe, and sensitive method for direct multielemental trace determinations in plutonium samples using total reflection X-ray fluorescence (TXRF) spectrometry has been developed. A very small volume (2 μL) of the sample solutions was deposited on TXRF supports after separation of the plutonium matrix from these solutions. Since the amount of the plutonium deposited on the supports was in the ng level only fixed on the supports and the specimen spots were not disturbed during the sample preparation, the samples could be analyzed directly without putting the instrument in a glovebox. This approach avoided a cumbersome operation of the instrument in a glovebox, which is normally utilized for Pu-based samples using other techniques. Similarly, the requirement of small amounts of the samples minimized the radiation dose to the operator as well as a cumbersome problem of management of radioactive analytical waste of plutonium samples. The samples were analyzed using the TXRF spectra of the specimens, concentration of the internal standard Se or Ga and predetermined sensitivity values. The elemental detection limits for the elements K-Sr varied from 1.06 to 0.09 ng. The elements K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Sr, Ba, Tl, and Pb were analyzed at μg/mL level. The analytical results of TXRF determinations showed average relative standard deviation (RSD) value of 4.5% (1σ, n = 3) and the TXRF determined results deviated from the expected values by 5.9% on average for samples prepared by adding multielements in plutonium solutions. Two real plutonium samples were also analyzed in similar manner. For the real plutonium sample solution the average RSD values of TXRF determinations were 10.6% (1σ, n = 3) for the elemental concentrations in the range of 0.2 to 61 μg/mL. These values are comparable with conventional trace element analytical techniques with added advantages mentioned above.

Assessment of Trace Element Distribution in Red-bloom (E. shafiqii) and Water of Dal Lake, Kashmir Valley, by Total Reflection X-ray Fluorescence Spectrometry

Dal Lake is located in Srinagar in the Jammu and Kashmir State of India. It is one of the foremost tourist attractions in the Himalayan valley as well as a lifeline for the local population. It provides fish, aquatic vegetables and drinking water. It has been plagued for the last 20 years by a thin red film during the period of June-August, when the tourist influx is at its peak. This phenomenon is attributed to a rare Euglena species Euglena shafiqii (Shafiq-ur-Rehman, 1998), which is now recognized and listed by the International Water Environment Renovation Research Team, Japan and the Society of Protozoologists. The lake frequently receives large quantities of wastes from the surrounding human settlements, hotels, and runoff from agricultural and Dachigam sanctuary catchment lands/area. All these activities make lake pollution prone. Our earlier observations have shown presence of some heavy metals in significant amount in the red-bloomed waters of the lake (Shafiq-ur-Rehman, 2009). The raised concentrations of heavy metals in lakes have also been reported from different parts of the world (Yalcin and Sevinc, 2001; Szymannowska et al., 1999; Elmaci, 2007). There are many spectrophotochemical techniques based on a range of physical principles encompassing the spectral range from Infrared to the X-Ray region (Wobrauschek, 1998). In the case when X-rays are used for elemental analysis their energy can range from 110 eV to about 130 keV (Be to Bk). Total Reflection X-ray Fluorescence (TXRF) is an upcoming trace elemental analysis technique having several advanced analytical features (Klockenkaemper and von Bohlen, 2001). Moreover, TXRF holds several analytical advantages of non-destruction and versatility of sample, capability to analyze multi-elements, and is less time consuming. It has comparatively high detection limits due to high background reduction produced by the absorption and scattering of X-ray beam by the sample and matrix (Misra and Mudher, 2002). In the present study TXRF was applied to determine the concentration of trace elements present in Dal Lake water besides the red-bloom Euglena shafiqii which appears in the lake in certain months of the year.

X-ray absorption near-edge structure (XANES) studies on Sb-doped Bi2UO6 at Bi and U edges

X-ray absorption spectroscopy (XAS) measurements at Bi and U LIII edges with synchrotron radiation have been carried out on Bi2−xSbxUO6 samples for x= 0.04, 0.08, 0.12, 0.16 and 0.40 which are possible by-products of Bi based coolant and Uranium based fuels in advanced high temperature nuclear reactors. The chemical shift of the Bi absorption edges in the samples have been determined accurately from the XANES region of the X-ray absorption spectra and have been explained in terms of the difference in electronegativity values of Sb and Bi. The chemical shift of absorption edges show systematic variation only upto x = 0.08 (i.e., 4% Sb doping), which shows that the Sb enter in the matrix properly up to 4% doping concentration. The local structure of U is found to remain unchanged on Sb doping indicating clearly that Sb dopants preferably replace Bi atoms.