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1
Synthesis of Ag-Loaded TiO2 Electrospun Nanofibers for Photocatalytic Decolorization of Methylene Blue

M. Raffi,Zaira Batool,Mashkoor Ahmad,M. Zakria,Rana I. Shakoor,Muhammad Aslam Mirza,Arshad Mahmood 한국섬유공학회 2018 Fibers and polymers Vol.19 No.9
- 복사/대출신청
Titanium dioxide (TiO2) is one of the excellent photocatalysts used for degradation of environmetal pollutants. In this work, 2.5, 5.0 and 7.5 wt.% of silver (Ag)-loaded TiO2 nanofibers of mean size 52-134 nm were synthesized by electrospinning method. These electrospun nanofibers were calcined at 500 oC to enable the transformation of Rutile (R) phase to Anatase (A), elimination of reaction moieties from the TiO2 matrix and subsequently formation of Ag clusters. The effect of Ag loading on the morphology, crystal structure, phase transformation, and band gap of these electrospun nanofibers have been characterized by scannining electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), raman spectroscopy and UV-visible spectroscopy. These nanofibers exhibited a red-shift in the absorbance edge and a significant enhancement of light absorption in the wavelength range of 250-550 nm. These electrospun nanofibers were investigated for photodecomposition of methylene blue (MB), and photocatalytic decolorization rates were determined by pseudo-first-order equation. The rate constants for the pure and those of 2.5, 5.0, and 7.5 wt% Agloaded TiO2 nanofibers were computed to be 0.1439 min-1, 0.1608 min-1, 0.1876 min-1, and 0.2251 min-1 respectively.
2
Probing of Potential Luminous Bacteria in Bay of Bengal and Its Enzyme Characterization

( Senthil S Balan ),( S M Raffi ),( S Jayalakshmi ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.6
- 원문보기 3
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  KCI
  
  KISS
The present study dealt with the isolation, identification and enzyme characterization of potential luminous bacteria from water, sediment, squid, and cuttle fish samples of the Karaikal coast, Bay of Bengal, India during the study period September 2007 - August 2008. Bioluminescent strains were screened in SWC agar and identified using bi℃hemical tests. As Shewanella henadai was found to be the most common and abundant species with maximum light emission [69,702,240 photons per second (pps)], the optimum ranges of various physic℃hemical parameters that enhance the luciferase activity in Shewanella hanedai were worked out. The maximum luciferase activity was observed at the temperature of 25℃ (69,674,387 pps), pH of 8.0 (70,523,671 pps), salinity of 20 ppt (71,674,387 pps), incubation period of 16 h (69,895,714 pps), 4% peptone (70,895,152 pps) as nitrogen source, 0.9% glycerol (71,625,196 pps), and the ionic supplements of 0.3% CaCO3 (73,991,591 pps), 0.3% K2HPO4 (73,919,915 pps), and 0.2% MgSO4 (72,161,155 pps). Shewanella hanedai was cultured at optimum ranges for luciferase enzyme characterization. From the centrifuged supernatant, the proteins were precipitated with 60% ammonium sulfate, dialyzed, and purified using anionexchange chromatography, and then luciferase was eluted with 500 mM phosphate of pH 7.0. The purified luciferase enzyme was subjected to SDS-PAGE and the molecular mass was determined as 78 kDa.
3
A Cenozoic record of the equatorial Pacific carbonate compensation depth

P채like, Heiko,Lyle, Mitchell W.,Nishi, Hiroshi,Raffi, Isabella,Ridgwell, Andy,Gamage, Kusali,Klaus, Adam,Acton, Gary,Anderson, Louise,Backman, Jan,Baldauf, Jack,Beltran, Catherine,Bohaty, Steven M.,Bo Nature Publishing Group, a division of Macmillan P 2012 Nature Vol.488 No.7413
- 원문보기
Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0??3.5??kilometres during the early Cenozoic (approximately 55??million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth.