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Ahmed Z.,University of Technology Malaysia | Hwang S.-J.,Center for Environmental Studies | Shin S.-K.,Sejong University | Song J.,Sejong University
Journal of Hazardous Materials | Year: 2010

The yeast strain Candida tropicalis was used for the biodegradation of gaseous toluene. Toluene was effectively treated by a liquid culture of C. tropicalis in a bubble-column bioreactor, and the toluene removal efficiency increased with decreasing gas flow rate. However, toluene mass transfer from the gas-to-liquid phase was a major limitation for the uptake of toluene by C. tropicalis. The toluene removal efficiency was enhanced when granular activated carbon (GAC) was added as a fluidized material. The GAC fluidized bioreactor demonstrated toluene removal efficiencies ranging from 50 to 82% when the inlet toluene loading was varied between 13.1 and 26.9 g/m3/h. The yield value of C. tropicalis ranged from 0.11 to 0.21 g-biomass/g-toluene, which was substantially lower than yield values for bacteria reported in the literature. The maximum elimination capacity determined in the GAC fluidized bioreactor was 172 g/m3/h at a toluene loading of 291 g/m3/h. Transient loading experiments revealed that approximately 50% of the toluene introduced was initially adsorbed onto the GAC during an increased loading period, and then slowly desorbed and became available to the yeast culture. Hence, the fluidized GAC mediated in improving the gas-to-liquid mass transfer of toluene, resulting in a high toluene removal capacity. Consequently, the GAC bubble-column bioreactor using the culture of C. tropicalis can be successfully applied for the removal of gaseous toluene. © 2009 Elsevier B.V. All rights reserved.

Subha Rajam K.,Lady Doak College | Rani M.E.,Lady Doak College | Gunaseeli R.,Center for Environmental Studies | Hussain Munavar M.,Madurai Kamaraj University
International Journal of Pharma and Bio Sciences | Year: 2013

The use of microorganisms in the synthesis of nanoparticles emerges as an ecofriendly approach. The microorganisms such as bacteria, fungi and actinomycetes and plant materials are used in the biosynthesis of nanoparticles. The biological synthesis of silver nanoparticles has many advantages over physical and chemical methods. In the present study, the isolated fungal strain Aspergillus sp. was used for silver nanoparticle synthesis. Cell free filtrate of isolated Aspergillus sp. was incubated with 1mM silver nitrate on a rotary orbital shaker at 120 rpm. The nanoparticles synthesis was visually observed by brown color change. The formation of silver nanoparticles was monitored by UV-Visible spectroscopy and further characterized by SEM, EDAX, Particle size and Photoluminescence analysis. The nanoparticles exhibited a maximum absorbance at 422nm in UV-Visible spectroscopy corresponding to the plasmon resonance of silver nanoparticles. SEM analysis reveals the nanoparticles with the size range of 40-70nm. The antibacterial effect of silver nanoparticles reported herein reveal its importance in advantage over conventional antibiotic against Pseudomonas aeruginosa.

When the Moon abruptly cuts off sunlight from Earth at a total solar eclipse, our weather reacts to the sudden darkness. A new issue of the Philosophical Transactions of the Royal Society of London, the oldest surviving scientific journal, deals with the effects of the March 20, 2015 eclipse. Williams College professor Jay Pasachoff, former Fulbright visitor to Williams College Marcos Peñaloza-Murillo, recent alumna Allison Carter '16, and University of Michigan postdoc Michael Roman have an article in this theme issue of "Phil Trans A" discussing the effect measured. Pasachoff and Carter had been on Svalbard, an Arctic archipelago controlled by Norway, for the eclipse. They had carried sensors for temperature and pressure borrowed from Williams College's Jay Racela of the Center for Environmental Studies. The expedition to Svalbard was supported by a grant to Pasachoff from the Committee for Research and Exploration of the National Geographic Society. The bulk of the theme issue was about the effect of the partial eclipse that was also visible from the U.K. The dimming of sunlight over the hour or so during the partial eclipse making its effects measurable. On Svalbard, for the total eclipse, the temperature and pressure automatic sensors found only slight effects, though a thermometer hanging from one of the camera tripods recorded a dip in temperature from the 8°F to which the morning temperature had risen down to –7° a few minutes after the center of totality. Pasachoff and Peñaloza-Murillo, who is professor emeritus at the Universidad de los Andes in Mérida, Venezuela, have published a previous paper about the effect of a total eclipse on weather, and are planning further observations, again in collaboration with Roman, at the August 21, 2017, total solar eclipse that they will attempt to observe from Salem, Oregon. This time the expedition will again be supported in part by the Committee for Research and Exploration of the National Geographic Society, and Williams College, with Pasachoff as Principal Investigator, has also received a research grant from the Solar Terrestrial Program of the Atmospheric and Geospace Sciences Division of the U.S. National Science Foundation. Pasachoff has also borrowed temperature and pressure sensors, a datalogger system called HOBO made by Onset Computer Corporation, as part of his observations of the September 1 annular solar eclipse this week. Pasachoff, along with Naomi Pasachoff, Research Associate at Williams College, is observing the eclipse from Isle de la Réunion in the Indian Ocean east of Madagascar. They are joined there by Rob Lucas of the University of Sydney; Michael Kentrianakis, project manager for the Eclipse 2017 Task Force of the American Astronomical Society; Stephen Bedingfield of Canada; and Xavier Jubier of France, who has provided Google Maps of various eclipse paths, accessible through the website http://eclipses.info that Pasachoff maintains as Chair of the Working Group on Solar Eclipses of the International Astronomical Union. This event is Pasachoff's 64th solar eclipse and the 16th annular solar eclipse. The theme issue of Phil Trans A, titled "Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse," has been edited by Giles Harrison of the University of Reading and Edward Hanna of the University of Sheffield, both in the UK. The article by Pasachoff, Peñaloza-Murillo, Roman, and Carter is entitled "Terrestrial atmospheric responses on Svalbard to the 20 March 2015 Arctic total solar eclipse under extreme conditions." Pasachoff drafted the article as part of his spring-2016 sabbatical leave in the Planetary Sciences Department of the California Institute of Technology. Another article, "Symbolism and Discovery: Eclipses in Art," by Ian Blatchford, head of the group that runs the Science Museum, London, draws heavily on and acknowledges work on the overlap of art and astronomy by Pasachoff in collaboration with art-historian Roberta J. M. Olson of the New-York Historical Society. The theme issue will be officially published on September 28, as volume 374, issue 2077, of Philosophical Transactions A, though the papers are already available online. The Phil Trans was established in 1665, making it the longest running scientific journal in the world. "Philosophical" refers to natural philosophy, an old term for what we know call "science." More information: Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse. rsta.royalsocietypublishing.org/content/atmospheric-effects-solar-eclipses-stimulated-2015-uk-eclipse

Chakrabarti S.,Center for Environmental Studies | Patra P.K.,Center for Environmental Studies | Mandal B.,Visva Bharati | Mahato D.,Center for Environmental Studies
Fluoride | Year: 2012

The influence of 0, 10, 20, and 30 mg NaF/L in an aqueous nutrient solution on germination, seedling growth, and biochemistry of Bengal gram (Cicer arieninum) seeds and seedlings was studied under controlled conditions. At the end of 15 days, significant reductions were observed with increasing F concentration in the various parameters studied, including percentage of seed germination, root and shoot length, biomass, vigor index, chlorophyll, and ascorbic acid content. F uptake by the roots and shoots of the seedlings increased with increasing F concentration, and although F accumulation in the roots was higher than in the shoots of the seedlings, the root-to-shoot translocation factor was quite high (>0.80). © 2012 The International Society for Fluoride Research Inc.

Chakrabarti S.,Center for Environmental Studies | Patra P.K.,Center for Environmental Studies | Mondal B.,Visva Bharati
Paddy and Water Environment | Year: 2013

The use of fluoride enriched groundwater for irrigating the paddy crops is prevalent in many parts of the world. The fluoride in the irrigated water not only affects the growth and productivity of the crops, but is also accumulated in the plant tissues. We studied the accumulation of fluoride in roots, leaves and seeds two paddy varieties (i. e. Oryza sativa L. var. IR-36 and Oryza sativa L. var. Swarno) when treated with different concentrations of fluoridated water. The translocation pattern of fluoride was also observed. The water soluble fluoride (FH2O) in the soil and plant parts increased substantially with increasing fluoride concentration in treated water. The Swarno variety showed a slight but consistent higher uptake of fluoride than the IR-36 variety. Fluoride uptake by the germinated seedlings was many folds higher than the uptake by mature plants. At 30 mg l-1 fluoride exposure, the mean FH2O accumulation (mg kg-1 dry weight) in root, leaves, and seeds of Swarno was 54. 1, 51. 4 and 42. 3, whereas the corresponding values in IR-36 were 50. 9, 48. 5 and 39. 2. For the same exposure, the fluoride accumulation in root and shoot of Swarno and IR-36 seedlings were 3,480, 3,463 and 3,386, 3,360 mg kg-1, respectively. Normally, the fluoride accumulation follows the order of soil > root > shoot > grain. However, at early stage of fluoride contamination (5 mg l-1 NaF) roots tended to hyper accumulate fluoride from the soil. © 2012 Springer-Verlag.

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