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ABSTRACT: Multiwall carbon nanotubes (MWNTs) decorated with CoO nanocrystals were synthesized by in-situ thermal decomposition of Co(acac) 2 in oleyl amine under reflux conditions open in the air. The CoO/MWNTs composite material can be easily converted to metallic Co/MWNTs through annealing under reducing atmosphere (4% H 2) at 500 • C without any significant sintering effect. The composite materials characterized by X-ray diffraction, transmission electron microscopy, and Nuclear Magnetic Resonance (NMR) spectroscopy. The structural and morphological characterization shows that the CoO has cubic face (fcc) and the particles deposited uniformly on the external surface of the carbon nanotubes. In the annealed materials, the NMR shows that the fcc and hcp metallic Co phases coexist with a significant percentage of stacking faults. The magnetic measurements indicated that the CoO/MWNTs composite is largely composed of CoO nanoparticles with uncompensated surface spins. The fluctuations of spins persist in partially reduced CoO grains as shown by nuclear spin-lattice relaxation measurements.
Hindawi Publishing Corporation Journal of Nanomaterials. 01/2011; 9.
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ABSTRACT: Twenty five F 2 progenies derived from the crosses involving HYV s and quality rices were evaluated during kharif 2005. Eleven biometrical characters were studied for estimating phenotypic variance, genotypic variance, genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), genetic advance, heritability (Broad sense), correlation coefficient and path coefficient among themselves. The analysis of variation revealed significant differences in the genotypes for all the characters studied. Per se performance of the progenies revealed that two F 2 progenies derived from the crosses IR-62 x Samba Mashuri and Kunti x Dudheswar were promising in respect of grain yield and some yield related traits. High GCV and PCV were observed for grain yield plant -1 , panicle number plant -1 and panicle weight. High heritability was observed against all the characters studied excepting panicle weight, grain number panicle -1 and grain breadth. Grain yield plant -1 showed maximum genetic advance as percentage of mean followed by panicle number plant -1 , plant height and panicle weight respectively. Grain yield plant -1 possessed significant positive correlation with panicle number plant -1 , panicle weight and grain number panicle -1 while it had significant negative correlation with plant height. Panicle number plant -1 imparted maximum direct effect on grain yield followed by grain number panicle -1 , 1000 grain weight and panicle length in this regard. Introduction Rice is the major cereal crop of South and South East Asia ninety percent of the world's rice is produced and consumed in this continent (Nanda, 2002). Most of the consumers, who depend on rice as their primary food, live in less developed countries. India occupies the first position in rice area and second position in production which almost tripled its production during the second half of the last century. Global demand for rice is projected to grow at least equal to population growth, thus requiring a 70% (765 mt) increase in supply of rice by the year 2025. In order to meet the future demand of rice, its production must be increased to match the rate of increase in population growth. Knowledge on genetic variability is the basic requirement in any crop improvement programme.
Electronic Journal of Plant Breeding. 08/2010; 1:758-763.
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ABSTRACT: Recently, studies have been taken up in world's leading nuclear research institutes to develop accelerator driven systems (ADS). Our department has earlier proposed a one-way coupled fast-thermal reactor of 750 MW (thermal). This reactor requires current in the range of 1–2 mA for proton beam of 1 GeV. A suitable liquid metal lead bismuth-eutectic (LBE) target based on buoyancy as well as gas driven method has been designed for this reactor earlier. In this paper, detailed thermal analysis in the spallation and window region has been carried out to study the operability of the target from thermo-mechanical point of view. FLUKA and computational fluid dynamics (CFD) codes have been used for this analysis. The results indicate that, the temperatures, thermo-mechanical stresses are within the required values. The detailed analysis of this work is presented in this paper.
Nuclear Engineering and Design 01/2007; · 0.76 Impact Factor
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ABSTRACT: The design of the spallation target system for accelerator driven systems requires a detailed understanding of the thermal-hydraulic issues involved as intense heat is deposited both in the window as well as in the target. Removal of heat from the window is a big thermal-hydraulic challenge. A lead–bismuth eutectic (LBE) experimental flow loop is currently being designed (1:1 size of an actual target both in terms of geometry and flow rate) to study thermal-hydraulics of the target system. It is proposed to simulate the proton beam heating of the window with a plasma heat source. In this paper, flow simulation studies have been performed for different target geometries and flow configurations with different window materials, which are proposed for the above said experimental loop. Optimal values of window geometry and flow configurations including the thermal loads the window experiences have been arrived at along with the required parameters for the plasma torch. The plasma torch has been tested and found to be suitable for simulation of proton beam heating in LBE loop to be set up.
Int. Jou. Heat and Mass Transfer. 01/2006; 49:3728-3745.
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International Journal of Heat and Mass Transfer 01/2006; 49. · 2.41 Impact Factor
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ABSTRACT: Selective oxidation induced void growth is observed in thermal barrier coating systems used in gas turbines. These voids occur at the interface between the bond coat (BC) and the thermally grown oxide (TGO) layer. In this paper we develop the modelling framework to simulate microvoid growth due to coupled diffusion and creeping in binary alloys. We have implemented the modelling framework into an existing finite element programme. The developed modelling framework and programme is used to simulate microvoid growth driven by selective oxidation in a binary β-NiAl alloy. Axisymmetric void growth due to the combined action of interdiffusion and creeping is simulated. The sharpness of the void and direction of creeping are considered as parameters in our study. Our simulations show that the voids dilate without any change in shape when creeping is equally likely in all the directions (isotropic). Void growth patterns similar to those observed in experiments are predicted when the creeping is restricted to occur only along the radial and tangential directions. A hemispherical void grows faster compared to a sharp void. The sharpness increases in the case of a sharp void and could lead to interactions with the neighbouring voids leading to spallation of the TGO layer as observed in experiments.
Modelling Simul. Mater. Sci. Eng. 01/2006; 14:1211-1223.
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ABSTRACT: with sero-negative polyarticular juvenile rheumatoid arthritis for 6 years, well controlled on sulfasalazine for 2 years, presented with acute flare up of arthritis of both knees, both ankles, right wrist and right shoulder joint of 5-day duration. He was confined to bed due to severe pain in knees and ankles. One week prior to the onset of this flare, he had suffered from dysentery (8-10 loose stools/day, mixed with blood) for 2 days, was treated with ciprofloxacin and metroindazole. There was no skin rash, redness of eyes, oral ulcers or back pain. There was no past history of similar episodes. Examination revealed pallor, hepatomegaly (3 cm below right costal margin), splenomegaly (just palpable), and a tender joint count of 7 and swollen joint count of 3. Investigations revealed normocytic, normochromic anemia (Hb 7.5 g/dL), raised inflammatory parameters (erythrocyte sedimentation rate-56 mm fall in first hour, C-reactive protein 3.5 mg/dL), platelets 4.5x10 5 /mm 3 , and normal renal and liver function tests. Stool examination was negative for ova, cyst blood or leucocytes. Levels of C3d bound immune complexes in the serum (29 µg /ml) and in the synovial fluid (65 µg /ml) were high EIA (normal <1.2 µg / ml). Levels of IgA rheumatoid factor (IgA RF) in polyethylene glycol-precipitated immune complexes isolated from serum (14.3 arbitrary units /ml) and synovial fluid (7.95 arbitrary units/ml) were high (EIA normal < 1.56 arbitrary units). However, IgM RF could not be detected in the im-mune complexes using EIA. He improved with oral diclofenac sodium (150 mg/d) and injection methyl prednisolone 60 mg in the right knee joint; on follow-up hemoglobin increased to 12 g/dL over the next 6 weeks. Discusia temporal relation-ship of gastro-intestinal infection and exacerbation of arthritis, which had been in sustained remission in our patient, may be coincidental. It may, on the other hand, reflect a cause and effect relationship. Increased levels of C3 bound immune complexes, and of IgA RF in the immune complexes in the serum and synovial fluid provide indirect evidence for triggering role of intestinal infection, though we failed to Post graduate Institute of Medical Sciences, Lucknow, India 226014. identify the organism that caused dysenteric illness. Increased level of IgA RF has been described in patients with Lyme arthritis 1 . Another possibility is that the patient had reactive arthritis in a setting of pre-existing Juvenile rheumatoid arthritis, however the joint involvement in lower limbs was symmetrical, unlike classical reactive arthritis. Several microbial agents like borrelia, brucella, and leptospira can trigger in a polyarticular illness, 2 similar to that seen in this patients. It is interesting that, in our patients joints were involved during the flare were the same as had been originally affected, it is therefore, possible that the original disease and the flare were caused by either the same microbial agent or those that share cross reactive epitopes 3 . An infectious etiology has often been considered but never proven for JRA. Of the three types of JRA (based on onset), systemic onset subgroup is most likely to have an infectious etiology. However, in some cases of polyarticular type of JRA, re-exposure to influenza A H2N2 was postulated as a precipitating factor in disease development 4,5 . Similarly, pauciarticular JRA has been linked to rubella, parvovirus, adenovirus and mycoplasma infections 5,6 . Enteric infection like Yersinia enterocolitica is a common cause of reactive arthritis in childhood 7 . Increased levels of C3d-bound immune com-plexes and of IgA RF in immune complexes in our patient at the time of disease exacerbation point towards a crucial role of immune complexes in the pathogenesis of acute synovitis. The analysis of microbial agent in the immune complexes could have provided further insight as to the cause of his flare. References: 1. Axford JS, Rees, DHE, Mageed RA, Wordsworth P, Alvia A, Steere AC. Increased IgA rheumatoid factor and VH1 associ-ated cross-reactive idiotype expression in patients with arthritis and neuro-borreliosis. Ann Rheum Dis 1999; 58: 757-61. 2. Toivanen, P, Toivanen A. Two forms of reactive arthritis? Ann rheum Dis 1999; 58:737-41. 3. Kishore, J. Misra R, Ayyagari A. Raised IgM antibodies to parvovirus B19 in juvenile rheumatoid arthritis. Indian J. Med. J. Antibodies to influenza A in a cluster of children with juvenile chronic arthritis. Br. J. Rheumatology 1988; 27: 176-80.
Res Arthritis Rheum Ann Med J. Rheumatol. 01/1998; 107(7):15-181232.
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ABSTRACT: In this paper, we describe our computational approach to understand the factors in¯uencing the selectivity of alkylation reactions over zeolite catalysts. Firstly, the shape, size and ¯exibility of the alkylated products are correlated to their diffusion behaviour inside zeolites. Secondly, the in¯uence of pore architecture and the dimension of various large pore zeolites on diffusion characteristics of alkylaromatics are brought out. Further, we study the isomorphous substitution of Al, Ga or B in the place of Si and their consequent in¯uence in the selectivity of alkylation reaction. We apply hard±soft acid±base (HSAB) principle which provides the properties to describe the acidity and reactivity of zeolites. The analysis of the results indicates that the shape selectivity in the alkylation reaction is also controlled by the molecular orbital properties in addition to the geometry constraints. # 1999 Elsevier Science B.V. All rights reserved.
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ABSTRACT: Temperature variations of the electron magnetic resonance (EMR) spectra and magnetization measurements are used to show that Ce 3+ ions in concentration =18% are present in 3 nm CeO 2 nanoparticles supported on silica aerogel. It is argued that the presence of Ce 3+ implies the defect structure CeO 2-x for ceria nanoparticles due to oxygen vacancies. This transformation of Ce 4+ to Ce 3+ driven by oxygen vacancies may be the key to understanding the catalytic properties of ceria.
