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Chakraborty B.,Bhabha Atomic Research Center | Modak P.,Bhabha Atomic Research Center | Banerjee S.,Indian Department of Atomic Energy
Journal of Physical Chemistry C | Year: 2012

Applying first principles electronic structure calculations and molecular dynamics (MD) simulations we have studied the structural stability, hydrogen adsorption capability and hydrogen desorption kinetics of Y-decorated single walled carbon nanotube (SWCNT). We have predicted that a single Y atom attached on SWCNT can physisorb up to six hydrogen molecules which is not reported so far. Our MD simulations with four Y atoms placed at the alternate hexagons of SWCNT showed no clustering effect of Y atoms at room temperature and also we found that the system is stable even at higher temperature (700 K). For the first time we showed that 100% desorption at comparatively lower temperature can be achieved in a transition metal-decorated SWCNT system. Therefore the Y-decorated SWCNT has the potential to become a promising hydrogen storage device. © 2012 American Chemical Society.

Vinod V.T.P.,Indian Department of Atomic Energy | Sashidhar R.B.,Osmania University | Sreedhar B.,Indian Institute of Chemical Technology
Journal of Hazardous Materials | Year: 2010

Gum kondagogu (Cochlospermum gossypium), an exudates tree gum from India was explored for its potential to decontaminate toxic metal ions in aqueous solution. The toxic metal ions nickel and total chromium biosorption capacity of the gum kondagogu were studied in the batch experimental mode. The optimum conditions of biosorption were determined by investigating pH, contact time, and initial metal ion and biosorbent concentrations. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and the data were analyzed on the basis of pseudo-second-order kinetic model. The maximum biosorption capacity of gum kondagogu as calculated by Langmuir model were found to be 50.5mgg-1 for nickel at pH 5.0±0.1 and 129.8mgg-1 for total chromium at pH 2.0±0.1, respectively. FTIR, SEM-EDXA and XPS analysis were used to evaluate the binding characteristics of gum kondagogu with metals. The experimental results demonstrate that the metal-ion interaction occurs through ion-exchange, adsorption and precipitation mechanisms. © 2010 Elsevier B.V.

Oxalate precipitation of lanthanides and thorium in acidic medium is a widely used group separation method at percentage to trace levels in different types of samples. In this report, a comparative study was made with the earlier reported conditions of trace level lanthanide separation as insoluble oxalates from a geological matrix at different pH values using calcium as carrier. The lanthanides and thorium are recovered quantitatively at trace levels as oxalates, using 300 mg calcium as a carrier at pH 1. The calcium is further removed by ammonium hydroxide precipitation in the presence of either stannic tin or ferric iron as the carrier. The combination of the two precipitative separations removed most of the matrix elements completely from the Ian-thanides and thorium at trace levels in different types of geological samples, such as igneous rocks, soils, and refractory minerals like ilmenite, rutile, columbite-tantalite, garnet and silliminite, as well as in certain environmental and industrial waste materials. Accuracy of the method was checked by analyzing some Canadian Certified Reference Project Materials such as syenite samples SY-2 and SY-3, gabro sample MRG-1, soil samples SO-1, SO-2 and iron formation sample FeR-2, and also synthetic samples. The lanthanide and thorium values obtained for the reference materials is comparable with the recommended values, indicating that the method is fairly accurate and reproducibility is characterized by a relative standard deviation CRSD) of 1 to 6% (n=4).

Complete and unequivocal preservation of natural water samples is a practical impossibility. The physico-chemical and biological changes continue inevitably after sample collection. In this paper, the various aspects which cause changes in the content of uranium, major cations and anions with reference to the time interval between sample collection and analysis are presented. These parameters warrant the need and use of Mobile Geochemical Laboratory for quick analysis of water samples. The reliability/quality of measurement results of water samples depends on strict adherence to each step of sampling, preservation of samples, time-interval between sampling and analysis for filtered but un-acidified water samples, and on the methodology adopted, and not simply analyzed by any person or lab or any technique. Interpretation and conclusions of hydrogeochemical reconnaissance survey will depend on the quality of measurement results. In addition to this, self-evaluation of data from collecting samples to reporting results should be carried out to ensure reliability and accuracy of analytical data of water samples.

Grover R.B.,Indian Department of Atomic Energy
Energy Strategy Reviews | Year: 2013

Considering growth in demand for modern energy services, renewable energy sources alone cannot meet future energy demand in India. The Government of India has, after examination of various options for green growth, reiterated the importance of accelerated development of nuclear energy along with other clean energy technologies. Several studies have indicated that nuclear technology stands out when compared to other electricity generating technologies on the basis of protection of climate and ecosystem, sustainability of fuel sources and reliability of supplies. India has set up necessary infrastructure to support growth of nuclear power and as a result of domestic research and development, and recent policy initiative, a range of reactor choices is available for deployment. India has also in place a sound domestic legal framework for governance of nuclear power and has signed various conventions including Convention on Nuclear Safety. The overall vision is to increase nuclear electricity generation to about 25% of total electricity generation by the middle of the century. © 2013 Elsevier Ltd.

When examined from the point of view of the size of its population and economy, India is not well endowed with energy resources. Studies done by the Department of Atomic Energy indicate that even after exploiting full potential of every available source of energy including nuclear energy, India needs to continue to import energy resources. In this backdrop, an initiative was launched by Government of India to open up international civil nuclear commerce so as to enable India to access natural uranium from international market and to set up nuclear reactors in technical cooperation with other countries. The paper provides details of what has been done so far, ongoing steps and likely growth scenario for nuclear installed capacity in the country. © 2011 Published by Elsevier Ltd.

Vinod V.T.P.,Indian Department of Atomic Energy | Sashidhar R.B.,Osmania University
Indian Journal of Natural Products and Resources | Year: 2010

Indian forests are a major source of large number of non-wood forest products. One such product is an exudate tree gum, regionally called as gum Kondagogu (Cochlospermum gossypium DC.), belonging to the family Bixaceae. This gum is collected by tribals in the state of Andhra Pradesh and marketed by Girijan Cooperative Society, Andhra Pradesh, India. Experimental work carried out in our laboratory on this gum has resulted in assigning a separate identity to this gum as compared to the well established and commercially exploited gum Karaya. Gum kondagogu has unique physiochemical properties as compared to other tree gums. Proximate analysis of the gum indicates that it has high volatile acidity and waterbinding capacity. Elemental composition of gum kondagogu was determined by Energy dispersive X-ray fluorescence spectrometry (EDXRF). Surface morphological studies based on SEM analysis showed irregular shape with sharp edges in the native gum, while the deacetylated gum showed a fibrilar and porous structure. AFM analysis indicated that native gum was visualized as spherical lumps, suggesting an inter- or intra-molecular aggregation. TEM image of native gum kondagogu showed that the polymer was an extending linear chain with branch points. FT-IR spectrum of native gum indicated the predominant presence of acetyl group (12%w/w). Analytical data on gum kondagogu indicated that the major neutral sugars were arabinose, mannose, α-D-glucose, β-D-glucose, rhamnose and galactose, whereas uronic acids (D-Glucuronic acid, β-Dgalacturonic acid and α-D-galacturonic acid) were the major acidic sugars. Structural assignment was carried out using acid hydrolysis, Smith degradation and NMR studies [1H, 13C, 2-D NMR (TOCSY and NOESY)]. Smith degradation analysis indicated that the back bone structure of gum kondagogu was that of α-D-GalpA-(1→4)-α-L-Rhap and can be grouped under rhamnogalacturonan type of gum. The experimental work provides enough evidence to exploit this natural biopolymer in food, textile and pharmaceutical industry.

The present invention relates to micro machined metal diaphragm for Fabry-Perot interferometer sensor and Fabry Perot Fiber optic Sensor system using said metal diaphragm and method of fabrication thereof. Fabry Perot sensor with micro machined metallic diaphragms at the fiber optic end is developed ensuring accuracy, controllability by deterministic process. Advantageously, the system involves the metal diaphragm with high reflectivity inside surface facing the fiber end as a basic functional element. Importantly, the micro machined metal diaphragm is miniaturized to suit various critical applications including bio medical sensing devices for measuring various physiological parameters with desired accuracy. The metallic diaphragm based Fabry-Perot fiber optic sensor is directed to favour wide scale applications such as for measuring various parameters in nuclear industry, Chemical and Electrically harsh industry, biomedical applications with desired precision and favorable performance largely unaffected by radiation, high temperature or highly corrosive environment at work/application.

Niobium or its alloy based Superconducting Radio Frequency (SCRF) Cavities involving at least one laser beam welded components in the SCRF cavity welded from inside surface of the wall of cavity directed to achieving more than half the thickness to full depth penetration with minimum HAZ, minimizing distortion and shrinkage. The method ensures improved weld quality and surface finish substantially free of any weld defects. Also disclosed is the welding nozzle system and welding rigs adapted to facilitate such laser welding of the Niobium or its alloy based Superconducting Radio Frequency (SCRF) Cavities. The invention is thus directed to enhancing productivity, ensuring consistent quality and reliability, enhanced weld penetration with minimum HAZ, smooth finish of weld joints at possible reduced costs.

A process for the preparation of high purity rare earth metal compounds such as oxides utilizing TBP (tri-butyl phosphate)-nitrate solvent extraction technique adapted to manufacture nuclear grade rare earth metal compounds such as zirconium oxide. The process substantially aids in reducing the specific generation of ammonium nitrate effluent volume thereby increasing its concentration when the effluent comprising ammonium nitrate and ammonium sulphate are utilized for stripping of the rare earth metal compound from the organic solvent in the said process of production of high purity rare earth metal oxide powder.

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