Monthly Archives: August 2019

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first_img Citation: Firm uses genetic modification to coax spider silk from silkworms (2011, April 14) retrieved 18 August 2019 from https://phys.org/news/2011-04-firm-genetic-modification-coax-spider.html The effort, conducted with research partners from the University of Notre Dame and the University of Wyoming, strove to combine the advantages of silk created by spiders, with silk created by silkworms. Spiders create webs from silk that has a very high tensile strength and is very elastic; it can be stretched to almost one and a half times its own length without a problem; but unfortunately, spiders aren’t big producers of such silk, needing only to create a simple web. Silkworms on the other hand are big producers of silk, due to their natural inclination to use it for creating a cocoon. Thus, it was deduced, if silkworms could be induced to create the same kind of silk as spiders, and at the same rate they normally produce regular silk, we humans could benefit by garnering rapidly produced strong silk.The research was led by Malcolm J. Fraser Jr., professor of biological sciences at Notre Dame and was founded on a process he has developed called the piggyBac, which is where a piece of DNA can be made to insert itself into the genetic material of a cell. Used in conjunction with Sigma’s proprietary CompoZr® Zinc Finger Nuclease (ZFN) technology, spider silk genes were transferred to silkworm cells, causing silkworms to produce a type of silk that is a combination of their natural silk, and that of the silk produced by a spider. The new silk, as yet unnamed, is far stronger and more flexible than any other silk ever produced by silkworms and the researchers believe that by removing some of the DNA material from the silkworm genes prior to the addition of spider material, they can produce something even better in the near future.Because techniques have already been developed for producing mass quantities of regular silk using silkworms, all of the parties involved are confident that they will soon be able to produce a silk so strong it might one day replace Kevlar in bullet proof vests, or provide surgeons with sutures strong enough, and elastic enough to allow them to perform life-saving procedures in far less time. It’s possible that one day this new super-silk might make regular silk something that’s only used for creating very soft comfortable clothes. Explore further © 2010 PhysOrg.com This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (PhysOrg.com) — In what many in the textile industry have for years been calling the holy grail of materials science, genetic engineers from Kraig Biocraft Laboratories Inc. have succeeded, using Sigma Life Science technology, in creating genetically modified silkworms that are able to produce a silkworm/spider silk combination that is much stronger and more elastic than natural silk, paving the way for improved products such as sutures, other medical devices and even airbags. Scientists genetically engineer silkworms to produce artificial spider silk (w/ Video)last_img read more

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first_img More information: Pascal Hartmann, et al. “A rechargeable room-temperature sodium superoxide (NaO2) battery.” Nature Materials. DOI: 10.1038/NMAT3486 The researchers, led by Professor Jürgen Janek and Dr. Philipp Adelhelm at the Institute of Physical Chemistry at Justus-Liebig-University Gießen in Gießen, Germany, have published their paper on rechargeable sodium-air batteries in a recent issue of Nature Materials.Li-air batteries’ greatest appeal is their high theoretical energy density (about 3,458 Wh kg-1), which is several times higher than that of Li-ion batteries, the most commonly used battery in electric vehicles today. However, whereas Li-ion batteries can be recharged many times while retaining most of their capacity, most Li-air batteries cannot be recharged at all. In 2011, several international groups discovered that this irreversibility is due to the instability of the Li-air battery’s electrolyte and other cell components in the presence of the reactive superoxide radical O2-, which forms as a first step during cell discharge. Only recently, improvements in rechargeability have been achieved by using gold electrodes, but the system still suffers from poor energy efficiency and large overpotentials in which some energy is lost as heat. In the new study, the researchers demonstrated that a sodium-air (Na-air) cell does not suffer from the same negative effects on the electrolyte and energy efficiency as a Li-air cell does. This is because, while lithium and sodium are closely related chemically, they each react very differently with oxygen. When lithium reacts with oxygen, it forms LiO2 (lithium oxide), which is highly unstable and found only as an intermediate species in Li-air batteries, after which it turns into Li2O2. On the other hand, sodium and oxygen form NaO2 (sodium superoxide), a more stable compound. Since NaO2 doesn’t decompose, the reaction can be reversed during charging. Lithium-air batteries’ high energy density could extend range of electric vehicles Scanning electron microscopy image of cubic NaO2 particles on the cathode after cell discharge. Image credit: P. Hartmann The scientists demonstrated the reversibility of Na-air cells in their experiments. Using several techniques, including Raman spectroscopy and X-ray diffraction, the scientists confirmed that NaO2 is indeed produced during discharge, that Na and O2 are separated during charging, and that the cycle can be repeated. Explore further (Phys.org)—Over the past few years, Li-air batteries (more precisely, Li-oxygen batteries) have become attractive due to their theoretical ability to store nearly as much energy per volume as gasoline. The key to this high energy density is the “air” part, since the batteries capture atmospheric oxygen to use in the cathode reaction instead of storing their own oxidizing agent. However, Li-air batteries have conventionally been single-use cells since they cannot be recharged, which significantly limits their applications. Now in a new study, scientists have found that replacing the lithium anode with a sodium anode may offer an unexpected path toward making metal-air batteries rechargeable while still offering a relatively high energy density. Copyright 2013 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of Phys.org. (Left) When a metal-oxygen battery is discharged, metal A (e.g., lithium or sodium) is oxidized at the anode/electrolyte interface, and the resulting electron is transferred to the outer circuit. At the cathode, oxygen is reduced to a superoxide species that may form a metal superoxide in the presence of the oxidized metal A. (Right) The metal superoxide in a Li-oxygen cell is highly unstable and reacts further. (Center) The metal superoxide in a Na-oxygen cell is much more stable and doesn’t decompose further, allowing the reaction to be reversed. Image credit: P. Hartmann, et al. ©2012 Macmillan Publishers Limited. Journal information: Nature Materials This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Sodium-air battery offers rechargeable advantages compared to Li-air batteries (2013, January 2) retrieved 18 August 2019 from https://phys.org/news/2013-01-sodium-air-battery-rechargeable-advantages-li-air.html “We could demonstrate that by replacing lithium with sodium, the cell reaction proceeds in an unexpected and beneficial manner,” Adelhelm told Phys.org. “The cell discharge and charge process is kinetically favored, which means that the formation and decomposition of NaO2 is very energy-efficient.”Although this evidence of reversibility is a promising step, the reaction is far from ideal. While Na-air batteries have a theoretical energy density of 1,605 Wh kg-1, which is significantly higher than that of Li-ion batteries, it is still only about half that of Li-air batteries. And even though the Na-air batteries can be charged and discharged several times, the capacity decreases after each cycle, with negligible energy storage after eight cycles. The researchers are currently investigating the processes that limit battery lifetime. Still, Na-air batteries have some attractive characteristics. One advantage of the Na-air battery demonstrated here is its very low overpotential, which is three or four times lower than for any Li-air or Na-air battery previously reported, resulting in fewer losses. In addition, sodium is the sixth most abundant element on Earth, while lithium resources are much more limited.”Our results are also important from another perspective,” Adelhelm said. “NaO2 is chemically very difficult to synthesize. High temperatures, pressures and long reaction times are needed. In our battery, NaO2 forms instantly at room temperature and ambient pressure. Possibly, also other chemical compounds could be prepared this way.”Overall, Adelhelm hopes that Na-air batteries may serve as one more option to turn to for future energy storage applications.”A broad variety of electrochemical energy storage devices with different properties is needed for future mobile and stationary applications,” he said. “In short, sodium’s abundance could be an important cost advantage over lithium; however, for otherwise identical batteries, the ‘lithium version’ will always provide the higher energy density. But any working metal/air battery will provide a higher energy density than current Li-ion batteries.”last_img read more

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first_img © 2014 Phys.org. All rights reserved. (a) A schematic of the hierarchical structure of a tree in which each structure is broken down to the level of the elementary fibrils. (b) Regular paper with microfibers has a microporous structure that causes light scattering. (c) The new paper is made of TEMPO-oxidized wood fibers to eliminate the micropores and improve optical transparency. Credit: Fang, et al. ©2014 American Chemical Society A team of researchers from the University of Maryland, the South China University of Technology, and the University of Nebraska-Lincoln, have published a paper on the new material in a recent issue of Nano Letters.As the researchers explain, solar cell performance benefits when materials possess both a high optical transparency (to allow for good light transmission) and a high optical haze (to increase the scattering and therefore the absorption of the transmitted light within the material). But so far, materials with high transparency values (of about 90%) have very low optical haze values (of less than 20%).The new wood-based paper has an ultrahigh transparency of 96% and ultrahigh optical haze of 60%, which is the highest optical haze value reported among transparent substrates.The main reason for this good performance in both areas is that the paper has a nanoporous rather than microporous structure. Regular paper is made of wood fibers and has low optical transparency due to the microcavities that exist within the porous structure that cause light scattering. In the new paper, these micropores are eliminated in order to improve the optical transparency. To do this, the researchers used a treatment called TEMPO to weaken the hydrogen bonds between the microfibers that make up the wood fibers, which causes the wood fibers to swell up and collapse into a dense, tightly packed structure containing nanopores rather than micropores. Citation: Future solar cells may be made of wood (2014, January 23) retrieved 18 August 2019 from https://phys.org/news/2014-01-future-solar-cells-wood.html Journal information: Nano Letters More information: Zhiqiang Fang, et al. “Novel Nanostructured Paper with Ultrahigh Transparency and Ultrahigh Haze for Solar Cells.” Nano Letters. DOI: 10.1021/nl404101p Explore furthercenter_img “The papers are made of ribbon-like materials that can stack well without microsize cavities for high transmittance, but with nanopores for high optical haze,” coauthor Liangbing Hu, Assistant Professor in the Department of Materials Science and Engineering at the University of Maryland, told Phys.org.To test the paper for solar cell applications, the researchers coated the wood fiber paper onto the surface of a silicon slab. Experiments showed that the light-harvesting device can collect light with a 10% increase in efficiency. Due to the simplicity of this laminating process, solar cells that have already been installed and are in use could benefit similarly from the additional paper layer.Although there are other papers made of nanofibers, this paper demonstrates a much higher optical transmittance while using much less energy and time for processing. With these advantages, the highly transparent, high-haze paper could offer an inexpensive way to enhance the efficiency of solar panels, solar roofs, and solar windows.”We would like to work with solar cell and display companies to evaluate the applications,” Hu said. “We are also interested in the manufacturing of such paper.” Optical transmission haze versus transmittance for different substrates at 550 nm. Glass and PET are in the green area, which are suitable for displays due to their low haze and high transparency; the transparent paper developed in this work is located in the cyan area, which is the most suitable for solar cells. Credit: Fang, et al. ©2014 American Chemical Society (Phys.org) —A new kind of paper that is made of wood fibers yet is 96% transparent could be a revolutionary material for next-generation solar cells. Coming from plants, the paper is inexpensive and more environmentally friendly than the plastic substrates often used in solar cells. However, its most important advantage is that it overcomes the tradeoff between optical transparency and optical haze that burdens most materials. Small-molecule solar cells get 50% increase in efficiency with optical spacer This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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first_img Explore further This insufficient or otherwise laggy inhibition of behavior has been linked to genetic alterations in various components of inhibitory neural transmission. One protein implicated here is known as gephyrin, which comes from Greek for the word ‘bridge’. It’s presumed occupation in synapses is to cluster gaba and glycine receptors to each other, and to the cytoskeleton. A curious thing about gephyrin is that it moonlights in another critical, if sometimes enigmatic role: it sits at the apex of a complex molybdenum cofactor synthesis chain, and pops a single Mo ion into the molybdopterin backbone ultimately used in least four human enzymes.Lurking beneath this ostensibly more ancient Mo insertion skill of gephyrin is a more sweeping Mo culture that has only recently been uncovered. According to Michael Russell from NASA’s Jet Propulsion Lab, there may likely have been an ‘ineluctable requirement’ for this second-row transition metal, and perhaps its column VI tablemate tungsten, at the origin of life itself. As Mo is the heaviest essential element we require (significantly heavier than Fe), it isn’t bred in standard stellar fusion reactions. The nucleosynthesis of Mo occurs at much higher energies in rapidly spinning gas giants and supernova explosions. It may therefore be the case that not just the birth of our solar system, but life on Earth required the eclectic services that local supernova provide.But this noble birth isn’t what makes Mo crucial to life. To understand why our sulfite oxidase, xanthine oxidase, aldehyde oxidase, and mitochondrial amidoxime reductase keep Mo on retainer to this day, we need to take a brief foray into the world of metallochemistry, electron bifurcation, and redox potentials. The main task is to identify what functions, if any, which Mo can perform that no other biometal can. But before that it is necessary to show that Mo was available to life at its origin. In the bacterial world, Mo, vanadium, and tungsten enjoy some limited degree of interoperability as cofactors. There are over 40 Mo enzymes in prokaryotes, many times more than the few used in us. Workhorses like the nitrogenases, which handle nearly all the global cycling of nitrogen through the biosphere use a special iron-molbdenum cofactor to fix dinitrogen gas. The Complex-Iron-Sulfur-Molybdoenzyme (CISM) superfamily members, which include such dignitaries as the primordial ferredoxins, have ubiquitous, if varied roles among prokaryotes. Discovery suggests possible revolutionary antibiotics While tungsten is rare, it would have been available to early life in both acid and alkaline solutions. Mo, although it is roughly 100 times more abundant, presents more of a challenge due to its insolubility in reduced and neutral waters. As with copper enzymes, geochemists have tended to assume that Mo (and its molybdate oxide anions) would not have been available, or at least soluble until oxygen-creating photosynthesis came on the scene some 2.5 billion years ago. The question of Cu availability raises an interesting point which I asked Russell about. Namely, in order to crown the molydopterin cofactor with its Mo, how did it come to be that gephyrin needs to replace a Cu atom that was pre-bound at an earlier synthesis step?It is widely accepted that the primitive atmosphere, and by implication the primitive ocean, were strongly reducing due to abundant H2, CH4, and H2S. Russell’s solution to the Mo availability problem is that the founding ‘cradle-of-life’ CISM-catalyzed reactions mentioned above were supplied with Mo by alkaline hydrothermal vents. He and his colleagues were able to reconstruct an enzyme phylogeny using multiple 3D structural alignments to show a likely CISM superfamily origin well before the divergence of LUCA, the presumed last universal common ancestor.But what is it exactly, that Mo offers? Part of the versatility of the elements Mo and tungsten comes from the fact that they are 2-electron redox compounds—they can shuttle between the +4/+5 and the +5/+6 redox couples. In other words, they can perform diverse and energetically challenging redox reactions. Practically speaking, this means that they can act as an electron sink or source at low redox potential. Furthermore, they seem to be the only elements that can effectively transfer oxygen and sulfur atoms during reactions taking place at low potential.Recall that redox potential is simply a measure, typically in millivolts, of the tendency of chemical species to acquire electrons and thereby be reduced. A high positive redox potential electron acceptor accepts electrons more readily than one of low potential. Some CISM enzymes can participate in ‘crossed-over’ redox transitions, which were likely critical in early and energetically challenging reactions. These so-called ‘electron bifurcation’ phenomena (which we will delve into in more detail in the next post), are now known to play a central role in a wide range of metabolisms, not least being the Q cycle component of the electron transport chain in mitochondria.A recent paper in Current Opinion in Chemical Biology by Guenter Schwarz describes some of the more practical, modern day incidentals of the Mo world. Of note he has been looking for a way to address problems in sulfite oxidase deficiency. Normally this enzyme transforms undesirable sulfite to sulfate by passing electrons from sulfite sequentially to its MoCo (Mo cofactor), then to its haem cofactor, and then ultimately to its terminal acceptor, cytochrome c. For a patient that might have a malformed or ill-placed oxidase, Schwarz is working on a replacement enzyme which lacks the haem. In this case, the enzyme behaves like the plant version and passes its electron to a terminal molecular oxygen.It’s not just in normal metabolism of sulfur-containing amino acids like methionine and cysteine that sulfite oxidase is critical. The current use of sulfur dioxide in food preservation and winemaking persists today in an unbroken tradition dating back to the early Egyptians and Romans who used fumes from burning sulfur as a sanitizing agent. The uptake and transport proteins our bodies use to bring in Mo from the environment, and distribute to various compartments within the cell does a fair job of discriminating between the similar sized sulfate and molybdate ions. Without proper handling, excess sulfite can lead to severe reaction.Similarly, problems with the xanthine oxidase system (or its MoCo units), can disrupt the normal metabolism of certain nucleotides into uric acid. One interesting part of MoCo synthesis is that it all begins in the mitochondria using the nucleotide GTP. Various enzymes ‘cycle’ the GTP, transforming its ribose into part of the canonical pterin ring structure that is so ubiquitous to the cofactors favored by early metabolisms. Pterins, named for the Greek word ‘pteron’, meaning wing, were first discovered in the bright pigments of butterfly wings.As for the gephyrin problems we originally mentioned, and the ‘stiff man’ and related symptoms which can result, the jury is still out. It may seem now that the issue is entirely due to the synaptic functions; a result of errors in the various exon cassettes used to construct and target gephyrin to receptors, or to antibodies subsequently made against the protein. MoCo units don’t even seem to be made in neurons—culture studies show their synthesis only occurs in astrocytes. However, the story of how the MoCo protein that sits atop the synthetic pipeline came into its critical new synaptic organization role likely holds a few more secrets. One form of MoCo cofactor: the molybdopterin ring structure with its Mo ion More information: Guenter Schwarz, Molybdenum cofactor and human disease, Current Opinion in Chemical Biology (2016). DOI: 10.1016/j.cbpa.2016.03.016AbstractFour molybdenum-dependent enzymes are known in humans, each harboring a pterin-based molybdenum cofactor (Moco) in the active site. They catalyze redox reactions using water as oxygen acceptor or donator. Moco is synthesized by a conserved biosynthetic pathway. Moco deficiency results in a severe inborn error of metabolism causing often early childhood death. Disease-causing symptoms mainly go back to the lack of sulfite oxidase (SO) activity, an enzyme in cysteine catabolism. Besides their name-giving functions, Mo-enzymes have been recognized to catalyze novel reactions, including the reduction of nitrite to nitric oxide. In this review we cover the biosynthesis of Moco, key features of Moco-enzymes and focus on their deficiency. Underlying disease mechanisms as well as treatment options will be discussed.center_img Citation: The jumping Frenchmen of Maine and the ineluctable requirement of molybdenum (2016, April 26) retrieved 18 August 2019 from https://phys.org/news/2016-04-frenchmen-maine-ineluctable-requirement-molybedenum.html © 2016 Phys.org (Phys.org)—The Jumping Frenchmen of Maine is a puzzling neurological syndrome named after a few peculiar 19th-century lumberjacks. Their defining symptom was an unnaturally exaggerated jumping reflex when startled. Georges Gilles de la Tourette included the disorder in his famous 1878 description of convulsive tic disorder, but to this day, its exact cause remains unknown. Among the many informative anecdotes associated with these particular French Canadians from Moosehead Lake, was that they could be inexplicably made to strike a dear loved one provided their agitator commanded it loudly enough. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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first_img © 2016 Phys.org (Phys.org)—An international team of astronomers has detected a highly inflated giant planet orbiting a mildly evolved star. According to a research paper published Aug. 16 on the arXiv pre-print server, the newly found exoplanet, designated KELT-12b, is one of the most inflated “hot Jupiters” known to date. More information: KELT-12b: A P∼5 Day, Highly Inflated Hot Jupiter Transiting a Mildly Evolved Hot Star, arXiv:1608.04714 [astro-ph.EP] arxiv.org/abs/1608.04714AbstractWe report the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting a mildly evolved host star. We identified the initial transit signal in the KELT-North survey data and established the planetary nature of the companion through precise follow-up photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the V=10.64 host, TYC 2619-1057-1, has Teff=6278±51 K, logg⋆=3.89+0.054−0.051, and [Fe/H] = 0.19+0.083−0.085, with an inferred mass M⋆=1.59+0.071−0.091M⊙ and radius R⋆=2.37±0.18R⊙. The planetary companion has MP=0.95±0.14MJ, RP=1.79+0.18−0.17RJ, loggP=2.87+0.097−0.098, and density ρP=0.21+0.075−0.054 g cm−3, making it one of the most inflated giant planets known. The time of inferior conjunction in BJDTDB is 2457088.692055±0.0009 and the period is P=5.0316144±0.0000306 days. Despite the relatively large separation of ∼0.07 AU implied by its ∼5.03-day orbital period, KELT-12b receives significant flux of 2.93+0.33−0.30×109 erg s−1 cm−2 from its host. We compare the radii and insolations of transiting giant planets around hot (Teff≥6250 K) and cool stars, noting that the observed paucity of known transiting giants around hot stars with low insolation is likely due to selection effects. We underscore the significance of long-term ground-based monitoring of hot stars and space-based targeting of hot stars with the Transiting Exoplanet Survey Satellite (TESS) to search for inflated giants in longer-period orbits. Explore further KELT-12b discovery light curve from the KELT-North telescope. The light curve contains 7,498 observations spanning 6.3 years. The light curve is phase-folded to the BLS-determined orbital period of 5.031450 days. The red points show the same data binned at 1.2-hour intervals after phasefolding. Credit: Stevens et al., 2016. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: One of the most inflated giant planets discovered (2016, August 22) retrieved 18 August 2019 from https://phys.org/news/2016-08-inflated-giant-planets.html A giant exoworld that expands in size when its parent star is at the end of its life is called “inflated.” This inflation process is very often seen in the so-called “hot Jupiters”—gas giant planets similar in characteristics to the solar system’s biggest planet, with orbital periods of less than 10 days. They have high surface temperatures as they orbit their parent stars very closely. The newly discovered KELT-12b is another great example of an inflated “hot Jupiter.”KELT-12b was spotted by a team of researchers led by Daniel Stevens of the Ohio State University. For their observations, the astronomers employed the KELT-North telescope at the Winer Observatory in Arizona. KELT-North is one of the two robotic telescopes in the Kilodegree Extremely Little Telescope (KELT) survey, whose main goal is to search for transiting exoplanets around bright stars.While analyzing KELT-North data acquired from 2007 to 2013, the scientists identified the initial transit signal of KELT-12b. Afterwards, the team conducted follow-up observations to confirm the planetary nature of this signal. They obtained several high-cadence, high-precision light curves from their global follow-up network of observers and small telescopes. “We identified the initial transit signal in the KELT-North survey data and established the planetary nature of the companion through precise follow-up photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging,” the researchers wrote in the paper.The newly found alien world is orbiting a mildly evolved, 2 billion-year-old star KELT-12 (also known as TYC 2619-1057-1) that is about 2.4 times larger than our sun and has a mass of approximately 1.59 solar masses. The planet itself, with an orbital period of five days, is slightly less massive than Jupiter, having about 0.95 the mass of the solar system’s gas giant. However, its radius is much larger than astronomers have expected – around 1.79 Jupiter radii. This relatively large radius, combined with an extremely low density at a level of just 0.21 g/cm3 indicates that KELT-12b is an inflated exoplanet. Moreover, the scientists emphasize that it is one of the most inflated “hot Jupiters” discovered so far.As the newest addition to the list of inflated gas giants, KELT-12b data could be helpful in future studies of the inflation process, as it is still unclear what really causes it. In general, the possible explanations could be assigned to two different theories—scientists believe that the inflation is caused by deposition of energy from the host star, or due to inhibited cooling of the planet.The authors of the paper hope that future studies will greatly expand our catalog of “hot Jupiters” around hot stars, adding new ones with orbital periods longer than a few days. It is expected to put researchers in a better position to investigate any differences in giant planet inflation, which could be crucial to our understanding of this process. Astronomers discover a highly inflated sub-Saturn extrasolar planetlast_img read more

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first_img Carbon-carbon bond formation at selective aliphatic carbon sites This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (Phys.org)—A trio of researchers with Princeton University has found a way to weaken the strong bonds between the nitrogen and hydrogen atoms in ammonia molecules while simultaneously releasing a single hydrogen atom to create hydrogen gas. In their paper published in the journal Science, Máté Bezdek, Sheng Guo and Paul Chirik describe the process and the likelihood of using it as a new hydrogen source. Jessica Hoover with West Virginia University offers a Perspective piece on the work done by the team in the same journal issue and also outlines the impact the findings are likely to have on hydrogen energy storage and utilization. Ammonia has long been used on a large scale to produce both fertilizers and feedstock, and on a smaller scale as a household cleaner, but scientists would also like to use it as a type of fuel, because doing so would offer a new way to create hydrogen gas for use as a clean energy source. But to date, efforts to do so have been stymied by the strong bond that exists between the nitrogen and hydrogen atoms in ammonia molecules. In this new effort, the researchers report that they have found an efficient means for doing so that not only weakens the bond, but also causes the release of one of the hydrogen atoms making it available to bond with another to create hydrogen gas.The new process involves using an ammonia-bound terpyridine bis(phosphine) molybdenum(I) cation, because as Hoover notes, it is both electron rich and positively charged. In so doing, the nitrogen–hydrogen bond is cleaved homolytically, resulting in a lone hydrogen atom and an M–N bond. The newly freed hydrogen atom is then able to bond with another to form hydrogen gas, which can then be collected, stored and eventually burned to provide energy for a variety of engines.The work by the team, Hoover also notes, is likely to have an impact both on energy systems (the process is much more efficient than other methods such as deprotonation or oxidative addition) and on other work that involves synthesizing ammonia, perhaps leading to even more efficient processes. Citation: Method found for pulling hydrogen from ammonia for use as clean fuel (2016, November 11) retrieved 18 August 2019 from https://phys.org/news/2016-11-method-hydrogen-ammonia-fuel.html © 2016 Phys.orgcenter_img Comparison of classical coordination compounds of ammonia and nonclassical compounds that enable bond weakening by coordination, which in turn enables hydrogen evolution. Credit: (c) Science  11 Nov 2016: Vol. 354, Issue 6313, pp. 730-733, DOI: 10.1126/science.aag0246 More information: Coordination-induced weakening of ammonia, water, and hydrazine X–H bonds in a molybdenum complex, Science  11 Nov 2016: Vol. 354, Issue 6313, pp. 730-733, DOI: 10.1126/science.aag0246 , http://science.sciencemag.org/content/354/6313/730AbstractAlthough scores of transition metal complexes incorporating ammonia or water ligands have been characterized over the past century, little is known about how coordination influences the strength of the nitrogen-hydrogen and oxygen-hydrogen bonds. Here we report the synthesis of a molybdenum ammonia complex supported by terpyridine and phosphine ligands that lowers the nitrogen-hydrogen bond dissociation free energy from 99.5 (gas phase) to an experimentally measured value of 45.8 kilocalories per mole (agreeing closely with a value of 45.1 kilocalories per mole calculated by density functional theory). This bond weakening enables spontaneous dihydrogen evolution upon gentle heating, as well as the hydrogenation of styrene. Analogous molybdenum complexes promote dihydrogen evolution from coordinated water and hydrazine. Electrochemical and theoretical studies elucidate the contributions of metal redox potential and ammonia acidity to this effect. Journal information: Science Explore furtherlast_img read more

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first_imgMacaca fascicularis at Ngarai Sianok, Bukittinggi, West Sumatra. Credit: Sakurai Midori /Wikipedia More information: Lydia V. Luncz et al. Technological Response of Wild Macaques (Macaca fascicularis) to Anthropogenic Change, International Journal of Primatology (2017). DOI: 10.1007/s10764-017-9985-6AbstractAnthropogenic disturbances have a detrimental impact on the natural world; the vast expansion of palm oil monocultures is one of the most significant agricultural influences. Primates worldwide consequently have been affected by the loss of their natural ecosystems. Long-tailed macaques (Macaca fascilularis) in Southern Thailand have, however, learned to exploit oil palm nuts using stone tools. Using camera traps, we captured the stone tool behavior of one macaque group in Ao Phang-Nga National Park. Line transects placed throughout an abandoned oil palm plantation confirmed a high abundance of nut cracking sites. Long-tailed macaques previously have been observed using stone tools to harvest shellfish along the coasts of Thailand and Myanmar. The novel nut processing behavior indicates the successful transfer of existing lithic technology to a new food source. Such behavioral plasticity has been suggested to underlie cultural behavior in animals, suggesting that long-tailed macaques have potential to exhibit cultural tendencies. The use of tools to process oil palm nuts across multiple primate species allows direct comparisons between stone tool using nonhuman primates living in anthropogenic environments. Journal information: International Journal of Primatology Explore further Monkeys in Brazil ‘have used stone tools for hundreds of years at least’ (Phys.org)—A team of researchers from the U.K., Thailand and Singapore has discovered that long-tailed macaques living in southern Thailand have learned to crack open oil palm nuts using rocks in just 13 years. The group reports on their observations and what they believe the observed behavior suggests about the evolution of tool use in primates in their paper published in the International Journal of Primatology.center_img There are a lot of animals besides humans that have learned to use tools, but only three have been observed using stones: chimpanzees, capuchins and macaques. In this new effort, the researchers were studying macaques that live in southern Thailand. Prior research and anecdotal evidence had found that they use stones to smash shellfish for consumption. But now, it appears the monkeys have applied what they learned with the shellfish to a different source of food.The researchers report that as part of their study of the monkeys, they followed them on inland treks. At one point, they wound up on an abandoned oil palm plantation. There, they found evidence of someone using stones to pound open oil palm nuts. To find out which creatures might be involved, they set up camera traps near the evidence.Reviewing the video, they witnessed several of the macaques approach a flat stone (used as an anvil), lay down a single nut and then smash it with a stone. Each finished by picking out the edible parts within and consuming them. The team reports that the oil palms have only been in the area for 13 years, suggesting that the monkeys learned to crack the nuts over the same period of time.The researchers plan to continue with their research, curious about how the transfer of knowledge to a new site and application came about. They plan to look for older evidence of such use in more remote locations. They suggest they might even find an evolution of the types of tools used by the monkeys, perhaps offering a glimpse of the process by which our ancestors accomplished the same feat. © 2017 Phys.org Citation: Macaques learn to crack open oil palm nuts with rocks in just 13 years (2017, September 7) retrieved 18 August 2019 from https://phys.org/news/2017-09-macaques-oil-palm-nuts-years.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

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first_img Citation: Ancient extinct cave bear DNA found in modern bears (2018, August 29) retrieved 18 August 2019 from https://phys.org/news/2018-08-ancient-extinct-cave-dna-modern.html Cave bear skull. Cave bears were giant bears, much bigger than living brown bears Credit: Andrei Posmoșanu Explore further Cave bears were a type of bear that lived in Asia and Europe. They were slightly larger than today’s brown bears, but fed on vegetation instead of meat. They went extinct approximately 24,000 years ago (during the Last Glacial Maximum) for unknown reasons. In this new effort, the research team was focused on learning why the bears went extinct. To that end, they conducted a DNA analysis on samples taken from four bear’s remains from approximately 35,000 years ago. Their goal was to study how the population of cave bears changed in size over long time periods. As an aside, they decided to compare the DNA from the extinct cave bears with modern bears.The researchers report that their comparison revealed that modern brown and polar bears both have cave bear DNA—on average 0.9 to 2.4 percent of their genome is cave bear DNA. They noted that the two types of modern bears are more genetically alike than they are to the cave bears. But they found that either was capable of mating with a cave bear, and that their offspring could breed with any of the three types, as well. They point out that their results are not surprising—the similarities between the bears, the overlapping time period in which they lived, and their habitat proximity made interbreeding a near-certainty. The finding of extinct cave bear DNA in modern bears is the first example of DNA from an ancient extinct species found in a modern species other than humans—we have remnants of Neanderthal DNA in our genomes. Ice age cave bear bones found in their former hibernation cave Credit: Marius Robu An international team of researchers has found evidence of extinct cave bear DNA in modern bears. In their paper published in the journal Nature Ecology & Evolution, the group describes their genetic analysis of modern brown and polar bears and how they compared with extinct cave bears. More information: Axel Barlow et al. Partial genomic survival of cave bears in living brown bears, Nature Ecology & Evolution (2018). DOI: 10.1038/s41559-018-0654-8AbstractAlthough many large mammal species went extinct at the end of the Pleistocene epoch, their DNA may persist due to past episodes of interspecies admixture. However, direct empirical evidence of the persistence of ancient alleles remains scarce. Here, we present multifold coverage genomic data from four Late Pleistocene cave bears (Ursus spelaeus complex) and show that cave bears hybridized with brown bears (Ursus arctos) during the Pleistocene. We develop an approach to assess both the directionality and relative timing of gene flow. We find that segments of cave bear DNA still persist in the genomes of living brown bears, with cave bears contributing 0.9 to 2.4% of the genomes of all brown bears investigated. Our results show that even though extinction is typically considered as absolute, following admixture, fragments of the gene pool of extinct species can survive for tens of thousands of years in the genomes of extant recipient species. Extinct vegetarian cave bear diet mystery unravelled Credit: CC0 Public Domain The researchers suggest that future research could explore what it means for a species to go extinct—if their DNA lives on in other species, are they really, truly gone? They note that their study reaffirms the fact that animal species interbreed, some regularly. That might have been the case with modern bears and cave bears—the ancient cave bears also had modern bear DNA in their gene pools. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2018 Phys.org Journal information: Nature Ecology & Evolutionlast_img read more

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first_imgTraining classes for the Indian Classic dance form Kathak are scheduled to begin at Kathak Nrityakala Kendra, in the Chicagoland Area of the United States. The academy was established by Anila Sinha Foundation in the year 1999, emphasizing a thorough study of Kathak dance, along with the associated subjects of music, choreography and stagecraft, with expert instructors from India.Kathak classes are conducted as individual private classes and as group classes. Also Read – ‘Playing Jojo was emotionally exhausting’Anila Sinha Foundation was formed in memory of Anila Sinha, who devoted herself in promoting and teaching classical musics and dances of India. The foundation is also looking forward to collaborate with the local dance and music institutes for cultural exchange and training in the United states. The foundation, a non profit organization has also planned to celebrate the Indian festival of colors ‘Holi’ on 23 March at Cutting Hall Performing Arts Center, Illinois.last_img read more

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first_imgTu Kaisi Maa- a play on cancer organized by Urvashi Dance Music  Art and Cultural Society with YOUWECAN was organised at Chinmay Mission, Lodhi Road in the Capital on December 18. Directed and performed by  Kathak exponent Rekha Mehra, Rekha Mehra, the play on disappearing daughters was a dance ballet on women empowerment with visual effects  in background. Kanya Bhrun hatya(female feticide)is a process of  aborting perfectly healthy fetuses after about 18 weeks (or more) of gestation just because they are females. Also Read – ‘Playing Jojo was emotionally exhausting’The occasion was graced by eminent personalities like Vijay Goel- Rajya Sabha  MP Satish Upadhyay- State(Delhi) President, BJP Shabnam Singh- (Cricketer Yuvraj Singh’s Mother) K.K.Miital- Additional Secretary, Ministry of Culture, Radha Mohan- Agricultural Minister. “We should bring an end to the violence that kills women, be it before birth, child abuse or domestic violence. These incidents threatens to remove the mask of modernity as we still remain in primitive society rooted in inequality and polarised by class, caste and religion” said  Rekha Mehra. Also Read – Leslie doing new comedy special with NetflixThe play talked about how the rape culture has rocked India due to inequality and due to traditions of embedded violence. Women are wonderful daughters, sisters, wives, and mothers. They should be loved, cared, respected and should be protected, she added.Education is a powerful tool for women. The play delves into improvement of women’s image, acceptance of family planning and women empowerment. Days are not far, when there may be a situation where brides will not be available for marriage as a result of female feticide. Let alone the issue of maintaining the lineage. India has a long way to go in her fight against pre-birth elimination of females. Time is quickly ticking away.last_img read more

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