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Jayasimhadri, M.,Jha, Kaushal,Ratnam, B.V.,Woo, Hyun-Joo,Jang, Kiwan,Rao, A.S.,Haranath, D. ELSEVIER SCIENCE 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.711 No.-
<P><B>Abstract</B></P> <P>In this work, Tb<SUP>3+</SUP> ions doped lead-germanate-tellurite (LGT) glasses were prepared by conventional melt quenching technique with different dopant concentrations ranging from 0.5 to 3.5 mol %. X-ray diffraction (XRD) and FT-IR analysis were carried out to analyze the structural properties of LGT glass. The excitation spectra revealed a single band centered in the NUV region at 380 nm by monitoring emission at 545 nm. The emission spectra consist of four bands, which are attributed to the <SUP>5</SUP>D<SUB>4</SUB>→<SUP>7</SUP>F<SUB>J</SUB> (J = 3–6) transitions. Among these transitions, the strong emission band was observed at 545 nm corresponding to the <SUP>5</SUP>D<SUB>4</SUB>→<SUP>7</SUP>F<SUB>5</SUB> transition and the optimized doping concentration of Tb<SUP>3+</SUP> ions was 2 mol %. The Huang's theory and I-H model indicate the possibility of energy transfer via electric dipole-dipole interaction between Tb<SUP>3+</SUP> ions. The CIE chromaticity coordinates were (<I>x</I> = 0.282 and <I>y</I> = 0.614) and emits intense yellowish green light. The decay curves measured for <SUP>5</SUP>D<SUB>4</SUB> level for the samples with different doping concentrations and the lifetime for the optimized sample was 548 μs. The results indicate that these glasses have potential applications in solid state lighting and display devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Optically transparent Tb<SUP>3+</SUP> doped PbO-GeO<SUB>2</SUB>-TeO<SUB>2</SUB> (LGT) glasses have been prepared. </LI> <LI> Excitation spectrum consists of single band in the NUV region at 380 nm. </LI> <LI> CIE coordinates indicate that Tb<SUP>3+</SUP> doped LGT glass emits yellowish green light. </LI> <LI> Huang's theory applied to reveal the energy transfer process between Tb<SUP>3+</SUP> ions. </LI> <LI> This glass may be potential to use in fabricating GaN based WLEDs. </LI> </UL> </P>
Ratnam, B.V.,Sahu, Mukesh K.,Vishwakarma, Amit K.,Jha, Kaushal,Woo, Hyun-Joo,Jang, Kiwan,Jayasimhadri, M. North-Holland 2017 Journal of luminescence Vol.185 No.-
<P><B>Abstract</B></P> <P>Europium activated NaCaPO<SUB>4</SUB> phosphor has been synthesized by various synthesis techniques such as solid-state reaction (SSR), molten salt synthesis (MSS) and sol-gel combustion (SGC) method to optimize the synthesis procedure. The comparative investigations of structural and luminescent properties have been studied to know the best synthesis method. The XRD patterns and Rietveld refinement analysis of the synthesized phosphors confirmed the single phase orthorhombic structure of NaCaPO<SUB>4</SUB>. Excitation spectra indicate the strong absorption in near ultraviolet (n-UV) region and the emission spectra exhibit strong emission band at 595nm corresponds to <SUP>5</SUP>D<SUB>0</SUB>→<SUP>7</SUP>F<SUB>1</SUB> transition under n-UV (λ<SUB>ex</SUB>=392nm) excitation. The SGC route synthesized phosphor exhibit intense emission than that of the SSR and MSS method. Therefore, the effect of dopant (Eu<SUP>3+</SUP>) concentration on the emission intensity and concentration quenching mechanism has been discussed in detail for the Eu<SUP>3+</SUP> doped NaCaPO<SUB>4</SUB> phosphor synthesized by SGC method. The CIE chromaticity coordinates have been calculated for the phosphors synthesized by SSR, MSS and SGC methods to reveal the emitting color and also to know the utility of this phosphor for white LEDs.</P>
Comparison of Different Techniques for Measurement of Cold Work in Mild Steel
Badgujar, B. P.,Jha, S. K.,Goswami, G. L. 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.6
There are various Non-Destructive Evaluation (NDE) techniques used for measurement of residual stresses in material, such as magnetic methods, X-ray diffraction, Ultrasonic velocity measurement etc. The capabilities, applications and limitations of these techniques for evaluation of cold work / plastic deformation were studied and compared. Mild steel plates were subjected to different degree of cold deformation and were analyzed by Magneto-mechanical Acoustic Emission (MAE), Barkhausen Noise (BN) and magnetic properties (hysteresis loop parameters analysis). Further, these specimens were analyzed by X-ray diffraction and ultrasonic velocity measurements. The microhardness measurement and microstructure studies of these cold worked plates were also carried out. The results of all these studies and comparison of different techniques are discussed in this paper.
Khambhaty, Yasmin,Mody, Kalpana,Jha, B. Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.6
The phenotypic and carrageenolytic features of a novel halo tolerant marine bacterium, isolated from decayed red algal samples collected along the west coast of India were studied. This gram-negative strain was identified as Pseudomonas elongata (MTCC 5261) syn. Microbulbifer elongatus comb. nov according to its morphological, physiological and molecular characterization. The extracellular k-carrageenase was purified 106.54-fold by a combination of ammonium sulfate precipitation $(40{\sim}60%)$ and successive gel filtration chromatography. The purified protein fraction yielded significantly high activity of 426.19 units/mg protein and migrated as a single band on a sodium dodecyl sulfate polyacrylamide gel electrophoresis with a molecular weight of ${\sim}128 kDa$. For k-carrageenase activity, optimum temperature was $40^{\circ}C$ whereas two pH optima i.e. 5.6 and 7.7 were observed. For k-carrageenan, the enzyme gave a $K_m$ value of 6.66 mg/mL and a $V_{max}$ value of $4{\mu}mol/min/mg$ when the reaction was carried out at $40^{\circ}C$ and pH 5.6. lsolated k-carrageenase could successfully generate protoplasts of Kappaphycus alvarezii. This is the first report on the production of k-carrageenase by this bacterium isolated from west coast of India. Molecular mass and various characteristics showed that the carrageenase from P. elongata was much different from those previously reported.
Optimization of Cobalt Loading in Co–CeO2 Catalyst for the High Temperature Water–Gas Shift Reaction
Lee, Y. L.,Jha, A.,Jang, W. J.,Shim, J. O.,Jeon, K. W.,Na, H. S.,Kim, H. M.,Lee, D. W.,Yoo, S. Y.,Jeon, B. H. Springer Science + Business Media 2017 Topics in catalysis Vol.60 No.9
<P>We varied the cobalt loading (10, 15, 25, 35 wt%) to determine the optimum loading in a Co-CeO2 catalytic system used for the high temperature water-gas shift (WGS) reaction. Severe reaction conditions were used to compare the catalytic performances including a very high gas hourly space velocity (142,663 h(-1)) and a high CO concentration (similar to 38%). Among the prepared catalysts, 15% Co-CeO2 exhibited excellent catalytic activity in the temperature range of 350-550 degrees C without promoting the methanation reaction. In addition, this catalyst showed relatively stable activity for 50 h at 400 degrees C. The outstanding performance of 15% Co-CeO2 catalyst is mainly due to the highest amount of dispersed cobalt atoms on the catalyst surface. Additionally, the WGS activity was affected by the oxygen vacancy concentration.</P>
Kalpana Mody,Yasmin Khambhaty,B. Jha 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.6
The phenotypic and carrageenolytic features of a novel halo tolerant marine bacterium, isolated from decayed red algal samples collected along the west coast of India were studied. This gram-negative strain was identified as Pseudomonas elongata (MTCC 5261) syn. Microbulbifer elongatus comb. nov according to its morphological, physiological and molecular characterization. The extracellular κ-carrageenase was purified 106.54-fold by a combination of ammonium sulfate precipitation (40~60%) and successive gel filtration chromatography. The purified protein fraction yielded significantly high activity of 426.19 units/mg protein and migrated as a single band on a sodium dodecyl sulfate polyacrylamide gel electrophoresis with a molecular weight of ~128 kDa. For κ-carrageenase activity, optimum temperature was 40℃ whereas two pH optima i.e. 5.6 and 7.7 were observed. For κ-carrageenan, the enzyme gave a Km value of 6.66 mg/mL and a Vmax value of 4 μmol/min/mg when the reaction was carried out at 40℃ and pH 5.6. Isolated κ-carrageenase could successfully generate protoplasts of Kappaphycus alvarezii. This is the first report on the production of κ-carrageenase by this bacterium isolated from west coast of India. Molecular mass and various characteristics showed that the carrageenase from P. elongata was much different from those previously reported.
S. K. Mandal,T. Ishimaru,B. Jha,D.C. Bhatt,H.V.Joshi 한국조류학회I 2006 ALGAE Vol.21 No.4
Amphora costata W. Smith 1853 is a down thrown diatom species and also known as metal corrosive ship-fouling organism. A. costata was isolated from Alang ship breaking yard, Alang and evaluated the toxicity tolerance and growth responses of the cultures exposed to different doses of toxic and relatively accessible heavy metals, such as Fe, Mn, Cd, Co, Cu, Zn, Ni, and Pb in the constantly monitored laboratory culture conditions. The strongest toxic effect was observed on A. costata exposed to Cd even at relatively low concentrations as compared to other metals . The following trend of decreasing order of toxicity i.e. Cd>Zn>Ni>Co>Pb>Cu>Fe was observed, when they were exposed to equal concentration and expose time.