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Dixit A.,Research Scholar | Kumar K.,BIT Mesra
Materials Today: Proceedings | Year: 2015

In the 21st century, the demand of manufacturing industries for light in weight of machines and machine parts is growing. In an aviation industry, aluminium composite having advantage of light weight and high mechanical properties like hardness, tensile strength, flexural strength etc, are used for body, propeller and other part of plane. In this present investigation, silica gel reinforced aluminium composite was fabricated with six various percentage of filler content. The tensile and flexural strength are estimated at three various speeds to analyze the mechanical properties of composite. The test were carried on the basis of Taguchi's L18 orthogonal array taking two design factors, speed and percentage of filler. Using Taguchi optimization method, optimum combination of these two factors was found. Tensile strength and flexural strength were analyzed on ANOVA (ANalysis Of VAriance) and generate regression equation. In this analysis, outcome is that most dominating factor which affecting tensile strength and flexural strength is percentage of filler content. At last confirmation test was conducted to validate the optimized process parameters. © 2015 Elsevier Ltd. Source


Pawar H.A.,Research Scholar
International Journal of Biological Macromolecules | Year: 2014

Seed galactomannans are neutral, heterogeneous polysaccharides widely distributed in nature. The Mannose/Galactose ratios differ from gum to gum, resulting in a change in structure, which in turn, determines the various industrial applications of seed galactomannans. Senna tora (Family: Fabaceae) is a fast growing and spreading under shrub of which seeds, pods and leaves are extensively used for medicinal applications. The seeds have been found to be an alternative source of commercial gums. The present investigation deals with isolation, purification and characterization of galactomannans from the seeds of Senna tora (S. tora). The galactomannan extraction was based on mechanical separation of the endosperm, water dissolution, centrifugation and precipitation with acetone. The polysaccharide obtained from S. tora seeds was characterized by using physicochemical and chromatographic procedures, as well as FTIR, Mass, 13C NMR and 1H NMR spectroscopy. The results indicated that the gum has the basic structure of galactomannans with a main chain of (1→4)-linked β-d-mannopyranosyl units to which single α-(1→6)-d-linked galactopyranosyl units are attached through block pattern. The rheological studies indicated that the S. tora gum (1%, w/w) solution possesses pseudoplastic flow. The viscosity and other rheological properties confirmed its suitability as an excipient in the development of sustained release delivery systems. © 2014 Elsevier B.V. Source


Shaji J.,Research Scholar
Natural Hazards | Year: 2014

The densely populated coastline of Thiruvananthapuram district of Kerala, along the southwest coast of India, is sensitive to sea surge and severe coastal erosion. The December 2004 Indian Ocean Tsunami had inundated several parts of this coastal zone, indicating nature of sensitivity. The present study is an attempt to develop a coastal sensitivity index (CSI) for Thiruvananthapuram coast within the framework of coastal sediment cells. Seven variables, namely (a) coastal slope, (b) geomorphology, (c) shoreline change, (d) mean sea-level rise, (e) nearshore slope, (f) significant wave height and (g) mean tide range, were adopted in calculation of CSI (the square root of the product of the ranked variables divided by the number of variables). Remote sensing data, topographic maps supported by field work and data from numerical models are used in geographic information system environment to generate CS index for each kilometer segment of this 76-km coastline. This study reveals that 72 % of the Thiruvananthapuram coastline falls in the high sensitive category. This exercise, first of its kind for Kerala coast will be useful for disaster mitigation and management. © 2014 Springer Science+Business Media Dordrecht. Source


News Article
Site: http://phys.org/biology-news/

"Our creation of a Cas9 variant that brings off-target effects to levels where we can no longer detect them, even with the most sensitive methods, provides a substantial advance for therapeutic applications in which you want to accurately hit your target without causing damage anywhere else in the genome," says J. Keith Joung, MD, PhD, associate chief for Research and the Jim and Ann Orr MGH Research Scholar in the MGH Department of Pathology, senior author of the Nature paper. "But its impact will also be incredibly important for research applications because off-target effects can potentially confound the results of any experiment. As a result, we envision that our high-fidelity variant will supplant the use of standard Cas9 for many research and therapeutic applications." Used to create targeted DNA breaks at which genetic changes can be introduced, CRISPR-Cas9 nucleases combine a bacterial DNA-cutting enzyme called Cas9 with a short guide RNA sequence that can bind to the target DNA sequence. While easier to use than previous gene-editing tools, CRISPR-Cas9 nucleases have a well-characterized and significant limitation. As described in 2013 studies led by Joung and others, CRISPR-Cas9 nucleases can induce off-target DNA breaks at sites that resemble the on-target sequence. Subsequent investigations by Joung's team and others have reduced but never completely and consistently eliminated these off-target effects. Joung and his colleagues hypothesized that reducing interactions between Cas9 and the target DNA might more completely eliminate off-target effects while still retaining the desired on-target interaction. The MGH team focused on the fact that certain portions of the Cas9 enzyme itself can interact with the backbone of the target DNA molecule. Pursuing an observation originally made by co-lead author Vikram Pattanayak, MD, PhD, of MGH Pathology, the team altered four of these Cas9-mediated contacts by replacing the long amino acid side-chains that bind to the DNA backbone with shorter ones unable to make those connections. "Our previous work suggested that Cas9 might bind to its intended target DNA site with more energy than it needs, enabling unwanted cleavage of imperfectly matched off-target sites," says Pattanayak. "We reasoned that, by making substitutions at these four positions, we could remove some of that energy to eliminate off-target effects while still retaining full on-target activities." Co-lead author Benjamin Kleinstiver, PhD, of the MGH Molecular Pathology Unit and Michelle Prew, a research technician in Joung's lab, then tested all 15 possible variants in which any combination of one, two, three or four of those amino acid side-chains were altered and found that one three-substitution and one four-substitution variant appeared to show the greatest promise in discriminating against mismatched target sites while retaining full on-target activities in human cells. The researchers then more fully characterized the four-substitution variant, which they called SpCas9-HF1 (Sp for the Streptococcus pyogenes bacteria, which is the source of this widely used Cas9, and HF for high-fidelity). They found that this variant induced on-target effects comparable to those observed with the original unaltered SpCas9 when used with more than 85 percent of 37 different guide RNAs they tested. Using GUIDE-Seq, a highly sensitive system Joung's lab developed in 2014 to detect off-target CRISPR-Cas9 effects across the genome, the team found that, while nucleases combining unaltered SpCas9 with seven different guide RNAs induced as many as 25 off-target mutations, use of SpCas9-HF1 produced no detectable off-target effects with six of those guide RNAs and only one off-target site with the seventh. These results were further confirmed using targeted deep-sequencing experiments. Joung's team also found that SpCas9-HF1 could reduce off-target effects when targeting atypical DNA sites characterized by repeat sequences of one or two nucleotides - sites that are typically subject to many off-target mutations. They developed additional derivatives of SpCas9-HF1 - called HF2, HF3 and HF4 - which could eliminate the few residual off-target effects that persisted with the HF1 variant and a small number of guide RNAs. "If SpCas9-HF1 using a certain guide RNA still produces a handful of off-target effects that are particularly difficult to eliminate, it may be possible to engineer new variants that get rid of even those effects," says Joung, who is a professor of Pathology at Harvard Medical School. The researchers also showed that SpCas9-HF1, like its naturally occurring counterpart, could be combined with other useful alterations that extend its utility. Previous work from the Joung lab published last summer in Nature had shown that introducing a series of amino acid substitutions could expand the targeting range of unaltered SpCas9. In the current study, the authors show that introducing these same alterations into SpCas9-HF1 also extended the targeting range of the high-fidelity variant. "These results show that these variants should be broadly useful to anyone currently using CRISPR-Cas9 technology," says Kleinstiver. "They can easily be used in place of wild-type SpCas9 and provide a highly effective method for reducing off-target mutations to undetectable levels." Explore further: New genome-editing platform significantly increases accuracy of CRISPR-based systems More information: Benjamin P. Kleinstiver et al. High-fidelity CRISPR–Cas9 nucleases with no detectable genome-wide off-target effects, Nature (2016). DOI: 10.1038/nature16526


News Article
Site: http://www.rdmag.com/rss-feeds/all/rss.xml/all

Some of the natural gas harvested by hydraulic fracturing operations may be of biological origin--made by microorganisms inadvertently injected into shale by oil and gas companies during the hydraulic fracturing process, a new study has found. The study suggests that microorganisms including bacteria and archaea might one day be used to enhance methane production--perhaps by sustaining the energy a site can produce after fracturing ends. The discovery is a result of the first detailed genomic analysis of bacteria and archaea living in deep fractured shales, and was made possible through a collaboration among universities and industry. The project is also yielding new techniques for tracing the movement of bacteria and methane within wells. Researchers described the project's early results on Monday, Dec. 14, at the American Geophysical Union meeting in San Francisco. "A lot is happening underground during the hydraulic fracturing process that we're just beginning to learn about," said principal investigator Paula Mouser, assistant professor of civil, environmental and geodetic engineering at The Ohio State University. "The interactions of microorganisms and chemicals introduced into the wells create a fascinating new ecosystem. Some of what we learn could make the wells more productive." Oil and gas companies inject fluid--mostly water drawn from surface reservoirs--underground to break up shale and release the oil and gas--mostly methane--that is trapped inside. Though they've long known about the microbes living inside fracturing wells--and even inject biocides to keep them from clogging the equipment--nobody has known for sure where the bacteria came from until now. "Our results indicate that most of the organisms are coming from the input fluid," said Kelly Wrighton, assistant professor of microbiology and biophysics at Ohio State. "So this means that we're creating a whole new ecosystem a mile below the surface. Not only are we fracturing the rock, we're giving these organisms a new place to live and food to eat. And in fact, the biocides that we add to inhibit their growth may actually be fueling the production of methane." That is, the biocides kill some types of bacteria, thus enabling other bacteria and archaea to prosper--species that somehow find a way to survive in water that is typically four times saltier than the ocean, and under pressures that are typically hundreds of times higher than on the surface of the earth. Deprived of light for photosynthesis, these hardy microorganisms adapt in part by eating chemicals found in the fracturing fluid and producing methane. Next, the researchers want to pinpoint exactly how the bacteria enter the fracturing fluid. It's likely that they normally live in the surface water that makes up the bulk of the fluid. But there's at least one other possibility, Wrighton explained. Oil and gas companies start the fracturing process by putting fresh water into giant blenders, where chemicals are added. The blenders are routinely swapped between sites, and sometimes companies re-use some of the well's production fluid. So it's possible that the bacteria live inside the equipment and propagate from well to well. In the next phase of the study, the team will sample site equipment to find out. The clues emerged when the researchers began using genomic tools to construct a kind of metabolic blueprint for life living inside wells, Wrighton explained. "We look at the fluid that comes out of the well," she said. "We take all the genes and enzymes in that fluid and create a picture of what the whole microbial community is doing. We can see whether they survive, what they eat and how they interact with each other." The Ohio State researchers are working with partners at West Virginia University to test the fluids taken from a well operated by Northeast Natural Energy in West Virginia. For more than a year, they've regularly measured the genes, enzymes and chemical isotopes in used fracturing fluid drawn from the well. Within around 80 days after injection, the researchers found, the organisms inside the well settle into a kind of food chain that Wrighton described this way: Some bacteria eat the fracturing fluid and produce new chemicals, which other bacteria eat. Those bacteria then produce other chemicals, and so on. The last metabolic step ends with certain species of archaea producing methane. Tests also showed that initially small bacterial populations sometimes bloom into prominence underground. In one case, a particular species that made up only 4 percent of the microbial life going into the well emerged in the used fracturing fluid at levels of 60 percent. "In terms of the resilience of life, it's new insight for me into the capabilities of microorganisms." The researchers are working to describe the nature of pathways along which fluids migrate in shale, develop tracers to track fluid migration and biological processes, and identify habitable zones where life might thrive in the deep, hot terrestrial subsurface. For example, Michael Wilkins, assistant professor of earth sciences and microbiology at Ohio State, leads a part of the project that grows bacteria under high pressure and high temperature conditions. "Our aim is to understand how the microorganisms operate under such conditions, given that it's likely they've been injected from surface sources, and are accustomed to living at much lower temperatures and normal atmospheric pressure. We're also hoping to see how geochemical signatures of microbial activity, such as methane isotopes, change in these environments," Wilkins said. Other aspects of the project involve studying how liquid, gas and rock interact underground. In Ohio State's Subsurface Materials Characterization and Analysis Laboratory, Director David Cole models the geochemical reactions taking place inside shale wells. The professor of earth sciences and Ohio Research Scholar is uncovering reaction rates for the migration of chemicals inside shale. Using tools such as advanced electron microscopy, micro-X-ray computed tomography and neutron scattering, Cole's group studies the pores that form inside shale. The pores range in size from the diameter of a human hair to many times smaller, and early results suggest that connections between these pores may enable microorganisms to access food and room to grow. Yet another part of the project involves developing new ways to track the methane produced by the bacteria, as well as the methane released from shale fracturing. Thomas Darrah, assistant professor of earth sciences, is developing computer models that trace the pathways fluids follow within the shale and within fracturing equipment. Though oil and gas companies may not be able to take full advantage of this newly discovered methane source for some time, Wrighton pointed out that there are already examples of bio-assisted methane production in industry, particularly in coal bed methane operations. "Hydraulic fracturing is a young industry," she said. "It may take decades, but it's possible that biogenesis will play a role in its future. Other researchers on the project hail from Pacific Northwest National Laboratory and the University of Maine.

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