Need-based Information Service in BARC

The organisation pattern of the Library and Information Services of the Bhabha Atomic Research Centre suitable for rendering effective need-based information service is explained. The method followed for assessing the information needs of the scientists is described, The various custom-buil t documentation services offered to meet the specific requirementc of the clientele are given indetail. It has been suggested that plans formulated should be periodically reviewed and necessary modifications be done with a view to get the best out of the system concerned

DESIGN OF SHAFT-BLADE ASSEMBLY FOR EFFECTIVE UTILIZATION OF MUD USED IN OIL AND GAS DRILLING

Mud has prominent role in drilling operation, it enhances to protect the drilling well from blowout by obstructing the formation pressure and failure. It gives exact information about presence of formation gasses and fluids at every part of the drilled hole. It‘s very essential to maintain mud with different proportions to have proper and un-interrupted drilling process. Because estimating earth formation is of much difficulty and active mud should readily available at every instant. In order to have proper and un-interrupted drilling process and to maintain mud with different proportions mud activating devices viz., mud-agitator and mud gun are used in existing mud tanks. On observation it is found that nearly 33% of mud in the tank is not influenced with these activating devices. Due to which the flow of mud from the tanks to the drill string is not in exact composition and also there is accumulation of mud chemicals[17] at the bottom of the tank which causes several problems. This paper emphasizes the design of shaft-blade assembly which runs horizontally along the length of the tank in order to activate mud in that tank effectively. The shaft-blade assembly was designed and analyzed in the ANSYS and from the results it was found that the stresses in the shaft-blade materials are well within the limits for the proposed design. Economic aspects of the design are also discussed in this paper at the end

Some aspects of curing of sharks and rays

A simple method for eliminating urea almost completely from elasmobranch muscle consists in desalting the initially salted muscle in 5% brine. The initial salting removes about 58% of the urea, which occurs to the extent of 5.8 to 7.5% D.W.B. in the fresh muscle, and the desalting further reduces the urea content to negligible quantities (0.2%)

Thesaurus - an ideal tool for vocabulary control in post-coordinate systems : INIS Thesaurus - a case study

The complex conceptual relationships contained in multi-dimensional documents present the problem of inconsistency in subject analysis and vocabulary control for efficient retrieval is stressed. The development of Thesaurus, an important contribution for effective vocabulary control in mechanised IR systems which is among the many developmental efforts in this direction, is highlighted. The development, structure and design of INIS Thesaurus is given in detail. Adaptability of the INIS thesaurus to a computer-based information handling system is examine

Combustion synthesis, characterization and Raman studies of ZnO nanopowders

Spherical shaped ZnO nanopowders (14-50 nm) were synthesized by a low temperature solution combustion method in a short time <5 min. Rietveld analysis show that ZnO has hexagonal wurtzite structure with lattice constants a = 3.2511(1) , c = 5.2076(2) , unit cell volume (V) = 47.66(5) () 3 and belongs to space group P63mc. SEM micrographs reveal that the particles are spherical in shape and the powders contained several voids and pores. TEM results also confirm spherical shape, with average particle size of 14-50 nm. The values are consistent with the grain sizes measured from Scherrer's method and Williamson-Hall (W-H) plots. A broad UV-vis absorption spectrum was observed at �375 nm which is a characteristic band for the wurtzite hexagonal pure ZnO. The optical energy band gap of 3.24 eV was observed for nanopowder which is slightly lower than that of the bulk ZnO (3.37 eV). The observed Raman peaks at 438 and 588 cm -1 were attributed to the E 2 (high) and E 1 (LO) modes respectively. The broad band at 564 cm -1 is due to disorder-activated Raman scattering for the A 1 mode. These bands are associated with the first-order Raman active modes of the ZnO phase. The weak bands observed in the range 750-1000 cm -1 are due to small defects. © 2011 Elsevier B.V. All Rights Reserved

EPR and photoluminescence studies of ZnO:Mn nanophosphors prepared by solution combustion route

Nanocrystalline ZnO:Mn (0.1 mol%) phosphors have been successfully prepared by self propagating, gas producing solution combustion method. The powder X-ray diffraction of as-formed ZnO:Mn sample shows, hexagonal wurtzite phase with particle size of ∼40 nm. For Mn doped ZnO, the lattice parameters and volume of unit cell (a = 3.23065 Å, c = 5.27563 Å and V = 47.684 (Å)3) are found to be greater than that of undoped ZnO (a = 3.19993 Å, c = 5.22546 Å and V = 46.336 (Å)3). The SEM micrographs reveal that besides the spherical crystals, the powders also contained several voids and pores. The TEM photograph also shows the particles are approximately spherical in nature. The FTIR spectrum shows two peaks at ∼3428 and 1598 cm−1 which are attributed to O–H stretching and H–O–H bending vibration. The PL spectra of ZnO:Mn indicate a strong green emission peak at 526 nm and a weak red emission at 636 nm corresponding to 4T1 → 6A1 transition of Mn2+ ions. The EPR spectrum exhibits fine structure transition which will be split into six hyperfine components due to 55Mn hyperfine coupling giving rise to all 30 allowed transitions. From EPR spectra the spin-Hamiltonian parameters have been evaluated and discussed. The magnitude of the hyperfine splitting (A) constant indicates that there exists a moderately covalent bonding between the Mn2+ ions and the surrounding ligands. The number of spins participating in resonance (N), its paramagnetic susceptibility (χ) have been evaluated

EPR, thermo and photoluminescence properties of ZnO nanopowders

Nanocrystalline ZnO powders have been synthesized by a low temperature solution combustion method. The photoluminescence (PL) spectrum of as-formed and heat treated ZnO shows strong violet (402, 421, 437, 485 nm) and weak green (520 nm) emission peaks respectively. The PL intensities of defect related emission bands decrease with calcinations temperature indicating the decrease of Zn i and V o + caused by the chemisorptions of oxygen. The results are correlated with the electron paramagnetic resonance (EPR) studies. Thermoluminescence (TL) glow curves of gamma irradiated ZnO nanoparticles exhibit a single broad glow peak at �343 °C. This can be attributed to the recombination of charge carriers released from the surface states associated with oxygen defects, mainly interstitial oxygen ion centers. The trapping parameters of ZnO irradiated with various γ-doses are calculated using peak shape method. It is observed that the glow peak intensity increases with increase of gamma dose without changing glow curve shape. These two characteristic properties such as TL intensity increases with gamma dose and simple glow curve structure is an indication that the synthesized ZnO nanoparticles might be used as good TL dosimeter for high temperature application. © 2011 Elsevier B.V. All Rights Reserved

Structural, EPR, photo and thermoluminescence properties of ZnO:Fe nanoparticles

Zn (1-x)Fe (x)O (1+0.5x) (x = 0.5-5 mol) nanoparticles were synthesized by a low temperature solution combustion route. The structural characterization of these nanoparticles by PXRD, SEM and TEM confirmed the phase purity of the samples and indicated a reduction in the particle size with increase in Fe content. A small increase in micro strain in the Fe doped nanocrystals is observed from W-H plots. EPR spectrum exhibits an intense resonance signal with effective g values at g â 2.0 with a sextet hyperfine structure (hfs) besides a weak signal at g â 4.13. The signal at g â 2.0 with a sextet hyperfine structure might be due to manganese impurity where as the resonance signal at g â 4.13 is due to iron. The optical band gap E g was found to decrease with increase of Fe content. Raman spectra exhibit two non-polar optical phonon (E 2) modes at low and high frequencies at 100 and 435 cm -1 in Fe doped samples. These modes broaden and disappear with increase of Fe dopant concentration. TL measurements of γ-irradiated (1-5 kGy) samples show a main glow peak at 368°C at a warming rate of 6.7°Cs -1. The thermal activation parameters were estimated from Glow peak shape method. The average activation energy was found to be in the range 0.34-2.81 eV. © 2012 Elsevier B.V. All rights reserved