More information: Stable optical lift, Nature Photonics (2010) doi:10.1038/nphoton.2010.266 PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen Cyclogyro Flying Robot Improves its Angles of Attack Play (PhysOrg.com) — Scientists in New York have predicted, observed and experimentally verified a micrometer-scale object being lifted only by a beam of laser light. Optical lifting may be useful for powering micromachines or improving the design of solar sails for interstellar space travel. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen 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. Unlike aerodynamic lift, which has gradual lift angles, the optical lift angles were around 60 degrees, which Swartzlander said was striking, very powerful, and could be compared to a plane taking off at 60 degrees. “Your stomach would be in your feet,” he said.Swartzlander described the findings as “almost like the first stages of what the Wright brothers did,” and said the next step would be to test lightfoils in air and experiment with a variety of materials with different refractive properties, and with other wavelengths of light. Explore further Citation: Optical lifting demonstrated for the first time (w/ Video) (2010, December 7) retrieved 18 August 2019 from https://phys.org/news/2010-12-optical-video.html Time-lapsed composite image (1.67 s per shot) of a semi-cylindrical rod lifting sideways from left to right near the bottom of a glass chamber, as a result of a transverse optical lift force. Image credit: Nature Photonics, doi:10.1038/nphoton.2010.266 Light has been known for some time to be capable of pushing objects and this is the principle behind the solar sail, which uses light to push vehicles along in space. Now, a new study by physicist Dr. Grover Swatzlander and colleagues of the Rochester Institute of Technology in Rochester, New York shows light is also capable of creating the more complex force of “lift,” which is the force generated by airfoils that make a plane rise upwards as it travels forward.In a paper that appeared online in Nature Photonics on December 5th, Swartzlander and colleagues describe their demonstration of light providing optical lift to tiny lightfoils. The experiment began as computer models that suggested when light is shone on tiny objects shaped like a wing a stable lift force would be created. Intrigued, the researchers decided to do physical experiments in the laboratory, and they created tiny, transparent, micrometer-sized rods that were flat on one side and rounded on the other, rather like airplane wings. They immersed the lighfoils in water and bombarded them with 130 mW ultraviolet laser light from underneath the chamber. As predicted, the lightfoils were pushed upwards by the light, but they also moved sideways in a direction perpendicular to the beam of light, in other words they were optically lifted. Symmetrical micro-spheres did not show the optical lift effect.In aerodynamic lift, which is created by an airfoil, the lift occurs because the wing shape causes air flowing under the wing to move more slowly and at higher pressure than that above the wing. In optical lift, created by a lightfoil, the lift is created within the transparent object as light shines through it and is refracted by its inner surfaces. In the lightfoil rods a greater proportion of light leaves in a direction perpendicular to the beam and this side therefore experiences a larger radiation pressure and hence, lift. © 2010 PhysOrg.com Play Videos: Nature Photonics, doi:10.1038/nphoton.2010.266
The Multi-Access-Box (MAB). (PhysOrg.com) — In an experiment designed to illustrate the different ways that animals use their own unique type of intelligence to accomplish certain goals, a team of zoologists and biologists from the University of Vienna and Oxford University, led by biologist Dr. Alice Auersperg have shown that New Caledonian crows and a type of green parrot called the kea, are both able to accomplish similar difficult tasks, but go about doing so in very different ways. In a paper published in PLoS ONE, the team describe how when confronted with a box with food inside, both species of birds showed high levels of intelligence in getting at that food, but went about doing so in ways uniquely suited to their physical and behavioral attributes. More information: Auersperg AMI, von Bayern AMP, Gajdon GK, Huber L, Kacelnik A (2011) Flexibility in Problem Solving and Tool Use of Kea and New Caledonian Crows in a Multi Access Box Paradigm. PLoS ONE 6(6): e20231. doi:10.1371/journal.pone.0020231AbstractParrots and corvids show outstanding innovative and flexible behaviour. In particular, kea and New Caledonian crows are often singled out as being exceptionally sophisticated in physical cognition, so that comparing them in this respect is particularly interesting. However, comparing cognitive mechanisms among species requires consideration of non-cognitive behavioural propensities and morphological characteristics evolved from different ancestry and adapted to fit different ecological niches. We used a novel experimental approach based on a Multi-Access-Box (MAB). Food could be extracted by four different techniques, two of them involving tools. Initially all four options were available to the subjects. Once they reached criterion for mastering one option, this task was blocked, until the subjects became proficient in another solution. The exploratory behaviour differed considerably. Only one (of six) kea and one (of five) NCC mastered all four options, including a first report of innovative stick tool use in kea. The crows were more efficient in using the stick tool, the kea the ball tool. The kea were haptically more explorative than the NCC, discovered two or three solutions within the first ten trials (against a mean of 0.75 discoveries by the crows) and switched more quickly to new solutions when the previous one was blocked. Differences in exploration technique, neophobia and object manipulation are likely to explain differential performance across the set of tasks. Our study further underlines the need to use a diversity of tasks when comparing cognitive traits between members of different species. Extension of a similar method to other taxa could help developing a comparative cognition research program. Citation: New study of crows and parrots highlights different types of intelligence (2011, June 9) retrieved 18 August 2019 from https://phys.org/news/2011-06-crows-parrots-highlights-intelligence.html Play This video shows the complex motor technique used by the male kea Kermit to insert the rod shaped tool into the appropriate opening. Video: PLOS ONE, doi:10.1371/journal.pone.0020231 In the video that accompanies the paper, it’s easy to see the differences in the bird’s makeup; the crows are careful and appear worried about being seen while working to get at the food, while the keas throw caution to the wind and attack the box with abandon, resorting to using the tools and such only when they find they can’t simply knock the box apart or turn it over. In some respects, it’s sort of like watching the difference between cats and dogs. Cats slowly stalk their prey, sneaking up on it and catching it by surprise, whereas dogs bound in, all engines firing, hoping to outrun or outlast whatever it’s trying to catch. © 2010 PhysOrg.com Explore further 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. PausePlay% buffered00:0000:00UnmuteMuteDisable captionsEnable captionsSettingsCaptionsDisabledQuality0SpeedNormalCaptionsGo back to previous menuQualityGo back to previous menuSpeedGo back to previous menu0.5×0.75×Normal1.25×1.5×1.75×2×Exit fullscreenEnter fullscreen But the experiment shows more than that as well; it permanently puts to rest the idea that we human beings exist on some sort of higher plane; in watching the birds work through the puzzle of trying to gain access to the food, you can see them thinking; especially the poor kea, when it finds it must push a small rod through a hole to get it’s reward. It’s beak was never meant for such a task, so, he resorts to using both beak and claws to work the rod until finally figuring out a way to push it through the hole and then to shove it at the food. You can’t help but wonder how some of us human beings would have done under similar circumstances. The box was constructed of clear see-through plastic and had four walls, each of which had a means of allowing access to a bit of food mounted on a pedestal in the center of the box. The first method, and the one that all the birds tested found the easiest, was a string protruding from a wall that was tied to the food; pulling on it resulted in the food being yanked off its platform and rolling downhill and out of the box. The next wall consisted of a hole with a tube leading downhill to the food; pushing a marble through the hole caused it to roll downhill knocking off the food. The next wall consisted of nothing but a hole in the wall, which meant to get the food treat, the birds had to shove a wooden rod through the hole to knock it off its pedestal. And lastly, the fourth wall had a window that could be opened outward by use of a hook, thus allowing access to the inside of the box and the treat. Crows demonstrate their cleverness with tools (w/ Video)
© 2011 PhysOrg.com Report shows data centers not using as much power as projected This is not the first time Koomey’s name has been in the news, just last month he was the lead author of a paper that showed that electricity consumed by data centers in the U.S. and around the world grew at a slower pace (from 2005 to 2010) than had been predicted by a 2007 U.S. EPA report. This time around, Koomey, in collaboration, with Intel and Microsoft has been studying how much electricity is used relative to processing power, by computers in a historical context. Way back in 1956, for example, ENIAC, one of the first true computers, used approximately 150 kilowatts of electricity to perform just a few hundred calculations per second. Using historical data, the team created a graph comparing the amount of computing power of the average computer (from supercomputers to laptops) with the amount of electricity it needed and found that over time, energy efficiency improvements from the 1950’s till now, have moved in virtual lockstep with increases in the amount of processing power: energy efficiency, they found effectively doubled every 1.57 year. Because of this, they predict that the trend is likely to continue into the foreseeable future.This is important as computing platforms have become more mobile and end users increasingly tend to place more value in power efficiency (because it means longer battery life) than in how fast their Smartphone or tablet is able to produce results. Thus, it’s possible that Koomey’s Law will become the rallying cry on into the future, much as Moore’s Law has been in the past. Though hopefully, new engineers won’t start to fudge on Moore’s Law to get these results, as that could lead to small devices that last for weeks on batteries alone, but are sluggish. (PhysOrg.com) — For most of the computer age, the central theme in computer hardware architecture has been: create more computational power using the same amount of chip space. Intel founder Gordon Moore even came up with a “law” based on what he’d seen up to that point to predict how things would go in the future; that computing power would double every year and a half. Now Jonathan Koomey, a consulting professor at Stanford has led a study that shows that the electrical energy efficiency of computers has been following roughly the same path. He and his colleagues from Microsoft and Intel have published the results of their study in EEE Annals of the History of Computing that shows that the energy efficiency of computers has doubled nearly every eighteen months (now called appropriately enough, Koomey’s Law) going all the way back to the very first computers built in the 1950’s. Transistor counts for integrated circuits plotted against their dates of introduction. The curve shows Moore’s law – the doubling of transistor counts every two years. Image: Wikipedia. Explore further More information: Implications of Historical Trends in the Electrical Efficiency of Computing, July-September 2011 (vol. 33 no. 3)pp. 46-54. doi.ieeecomputersociety.org/10.1109/MAHC.2010.28AbstractThe electrical efficiency of computation has doubled roughly every year and a half for more than six decades, a pace of change comparable to that for computer performance and electrical efficiency in the microprocessor era. These efficiency improvements enabled the creation of laptops, smart phones, wireless sensors, and other mobile computing devices, with many more such innovations yet to come. The Web Extra appendix outlines the data and methods used in this study.via Technology Review Citation: New ‘Koomey’s Law’ of power efficiency parallels Moore’e Law (2011, September 15) retrieved 18 August 2019 from https://phys.org/news/2011-09-koomeys-law-power-efficiency-parallels.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.
© 2014 Phys.org Finding supports model on cause of DNA’s right-handed double helix Handedness is a complicated business. To simply say life is left-handed doesn’t even begin to capture the blooming hierarchy of binary refinements it continues to evolve. Over the years there have been numerous imaginative theories for how life’s amino acids, nucleic acids, and sugars came to favor one orientation over another. Everything from circularly polarized UV light, magnetism of the Earth, oriented clays or quartzes, to the weak nuclear force itself has been considered, but none has yet to securely emerge into realm of plausibility. A recent paper by Dreiling and Gay in Physical Review Letters has now thrown a life jacket to the weak force making it a theoretically viable possibility. To fully vet the author’s conception a little work needs to be done. Effort well spent we might say, because to understand where and when the handedness of life’s molecules originated is to know the origin of life. Citation: The origins of handedness in life (2014, October 1) retrieved 18 August 2019 from https://phys.org/news/2014-10-handedness-life.html Journal information: Physical Review Letters Explore further The capital “L” forms of aminos acids are the chiral orientations mostly preferred in our proteins. They are said to be left-handed when referenced to the optical activity of an L-glyceraldehyde molecule from which they could in theory be derived. However nine of our nineteen L-amino acids are actually dextrorotatory with a lowercase d (rotate polarized light to the right), when measured at the standard optical wavelength of 589 nm. Similarly the D orientation of glucose, the dextrose of life, rotates light to the right, while D-fructose actually rotates it to the left. The handedness of the DNA helix is more straightforward to assign than values for optical rotation of constituent molecules with multiple chiral centers. The A-DNA helix which life mostly employs, threads to the right when viewed from either direction as sure as a nut threads in either direction on the machinist’s screw. While the debate continues on the exact order in which the many key molecules of life first appeared, amino acids have been the center of attention. One possible explanation for their chirality is that circularly polarized (CP) light preferentially destroyed one amino acid enantiomer over the other, potentially giving it a head start. This idea gained some support when CP radiation in the infrared band was discovered in the Orion Nebula. The main problem with this idea is that CP also destroys much of the “correct” amino acid form as well. Moreover, the magnitude and orientation preference for the effect depends on the frequency of the light. The desireable bias—L selection for the narrow UV light band—would be swamped by competing broadband effects with the result that any long term amplification would grow asymptotically small.Experimentatlly, the CP theory of handedness is not completely dead, only weak. The best result to date has been the creation of 20% optically pure camphor in the lab. Unfortunately this was only obtained after 99% of the original stock was destroyed. If the D form amino acids are life’s cancer, than CP light hardly seems to be the most effective chemotherapy. The weak nuclear force, one the other hand, may be a bit more interesting for the origins of chirality. It is one of the four fundamental forces of nature and governs a particular kind of radioactive decay known as β-decay. The weak force has a peculiar handedness, called parity violation, which preferentially produces left-handed electrons during β-decay. For electrons with a left-handed “helicity”, the directions its of spin and motion are opposite to each other. More information: Chirally Sensitive Electron-Induced Molecular Breakup and the Vester-Ulbricht Hypothesis J. M. Dreiling and T. J. Gay, Phys. Rev. Lett. 113, 118103 – Published 12 September 2014. journals.aps.org/prl/abstract/ … ysRevLett.113.118103 Chirality of life. Credit: wikipedia Richard Feynman Beta decay, and the events occuring around it, are perhaps much better described with Feyman diagrams than with words. For many of us, simply explaining why a mirror “appears” to flip left and right but not top and bottom requires more than just imagining circling around it to appear inside it. Determining the far more complex mechanisms that underlie life’s handedness will likely remain a significant challenge for some time. In 1967 Vester and Ulbricht suggested that spin-polarized electrons could have directly generated the kind of CP light described above (as so-called bremsstrahlung radiation) to directly enrich the enantiomeric precursors of life. While notable, that mechanism leaves us right back where we were with the CP light shortcomings mentioned above. In this void, other researchers have suggested the polarized electrons themselves, either from radioactive decay or as cosmic rays hailing at the appropriate energy, might be the emissaries of chirality. Against this tableau of uncertaintly there is an interesting theoretical implication of parity violation. That is that both L-amino acids and D-sugars are slightly more stable then their opposites. Unfortunately, the energy differences we are talking about here are only about 10–17 kT. In a racemic mixture of L and D form amino acids, that energy corresponds to an L excess of only one per every 6×10^17 molecules.Finding evidence that direct beta interactions can transmit chirality to organic molecules has been difficult. What distinguishes the results just reported by Dreiling and Gay is that the uncertainty regarding a photonic or electronic mechanism can be reduced by mimicking beta radiation with longitudinally polarized electrons produced in the laboratory at a precisely controllable energy. The researchers used a brominated form of camphor in which an electron could cause release of the bromine in a process known as dissociative electron attachment (DEA). The key to their success was to use incident electrons with low velocity and energy to maximize the “chirality sampling” interactions.In a nutshell, they found that left-handed bromocamphor reacted better with right-handed electrons at modest energies, and better with left-handed electrons at the lowest energies. The effect was small, but enough to take the Vester-Ulbricht Hypothesis to the next level. 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.
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 team of researchers with Second University of Naples has developed a model that may help explain how it is that some earthquakes set off other earthquakes up to a thousand miles away. In their paper published in Physical Review Letters, the team describes how they constructed a physical model, watched how it behaved under stress and then came up with their theory. More information: Dynamic Weakening by Acoustic Fluidization during Stick-Slip Motion, Phys. Rev. Lett. 115, 128001 – Published 15 September 2015. dx.doi.org/10.1103/PhysRevLett.115.128001ABSTRACTThe unexpected weakness of some faults has been attributed to the emergence of acoustic waves that promote failure by reducing the confining pressure through a mechanism known as acoustic fluidization, also proposed to explain earthquake remote triggering. Here we validate this mechanism via the numerical investigation of a granular fault model system. We find that the stick-slip dynamics is affected only by perturbations applied at a characteristic frequency corresponding to oscillations normal to the fault, leading to gradual dynamical weakening as failure is approaching. Acoustic waves at the same frequency spontaneously emerge at the onset of failure in the absence of perturbations, supporting the relevance of acoustic fluidization in earthquake triggering. © 2015 Phys.org Earthquakes, as most everyone knows, happen when compressed rock slides against other rock along a fault line—but what researchers have struggled to understand is how or why some earthquakes seem to cause other earthquakes to occur, that are too far away to be chalked up to mere ground vibrations.To better understand what happens, the researchers set up some rocks in their laboratory, with some round granules between them—then applied pressure. As the rocks finally slipped, mimicking a real earthquake, the team recorded what happened with the grains between them. They found that they emitted acoustic waves. Next, they tried a similar experiment, but this time, broadcast a variety of acoustic waves in the vicinity of the grains—doing so revealed that for certain frequencies, the acoustic waves caused what the team describes as “lathering” where fluid-like motion occurred resulting in a sudden reduction in friction, causing the rocks on either side to slide against one another earlier than they would have otherwise. And that, the researchers suggest, might be what happens when one earthquake sets off another a long distance away—the sound waves created by one earthquake travel long distances to another site, cause the grains in a fault line they encounter to lather, and that is what sets off another earthquake. The lathering occurs, the researchers suggest, due to waves bouncing back and forth inside a fault.The results beg the question: Why don’t all earthquakes set off lots of other earthquakes in distant places? The answer, the team notes lies in the frequency of the acoustics waves—lathering only occurs for any given fault line within a certain narrow frequency range, and the impact they have will depend on the state of other fault lines—they have to be near ready to slip on their own.The idea put forth by the team should not be too difficult to study in real situations, as acoustic recordings that occur in the vicinity of earthquakes could be compared with those captured at distant sites that have what appear to be, related seismic events. Explore further Seismogram being recorded by a seismograph at the Weston Observatory in Massachusetts, USA. Credit: Wikipedia Megathrust quake faults weaker and less stressed than thought Citation: Study offers explanation for earthquakes setting off distant quakes (2015, September 22) retrieved 18 August 2019 from https://phys.org/news/2015-09-explanation-earthquakes-distant-quakes.html Journal information: Physical Review Letters
What if you could launch a machine aboard a rocket to Mars and then transmit information describing a life form, which the machine then “prints?” That is what the team at SG envisions. Or more practically, they envision sending the digitized DNA of a deadly virus from a remote outbreak zone to a research lab that uses the information to develop a vaccine. Once created, the same converter machine could then be used to print the material for creating the vaccine locally.The device is actually a hodgepodge of smaller devices that contribute to the whole. One of the main pieces is the BioXP 3200—a synthetic DNA printer that is already marketed around the world to researchers who use it to easily create synthetic DNA samples. The rest of the pieces receive information and process it and deal with the printed materials—the head of the project at SG, for example, can send a message from his office to the machine and then walk over and collect a virus it has created. This is not a means for creating life, the researchers note, because viruses are not considered forms of life. Instead, it is described as a “digital to biological converter for on-demand production of biologics.”Researchers at SG have used the device to remotely synthesize viruses and claim they are on the cusp of doing the same with a so-called minimal cell, a major step toward remotely printing material for creating living organisms. But first, they have to fix what they describe as an unacceptable rate of mutations.In their paper and announcement, the company highlights the positive uses for the machine, but notably avoid mentioning the negative—the ability to use the machine to produce a virus at a given location that could be released as a biological weapon. Citation: Synthetic Genomics unveils digital-to-biological converter using digital DNA to print biologics (2017, August 7) retrieved 18 August 2019 from https://phys.org/news/2017-08-synthetic-genomics-unveils-digital-to-biological-digital.html Credit: CC0 Public Domain Using machine vision for 3-D printing © 2017 Phys.org More information: Kent S Boles et al. Digital-to-biological converter for on-demand production of biologics, Nature Biotechnology (2017). DOI: 10.1038/nbt.3859 Journal information: Nature Biotechnology 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. A team of researchers at Synthetic Genomics (SG) has unveiled a machine they call a digital-to-biological converter—it sends digitized information describing DNA, RNA or a protein to a device that prints out synthesized versions of the original material. The team has published a paper describing their creation in the journal Nature Biotechnology. Explore further
Researchers explore how chewing affects teeth on the nanoscale The fossils were excavated at a dig site called Velaux-La Bastide Neuve on the southern coast of France—a site that has given up many other fossils. The researchers suggest the most notable thing about the dinosaur, which has been named Matheronodon provincialis, was its teeth. Not only were they quite large for a dinosaur of its size, but they were fewer in number. The researchers note that some of the teeth were 6 centimeters long and others up to 5 centimeters wide. As a member of the rhabdodontids, they had teeth with ridges covered by enamel on just one side—the other side had very little enamel and no ridges. Teeth that were located on the upper jaw were situated such that the enamel and ridges were on the outer side, while the teeth on the bottom jaw were the opposite. The net effect was a mouthful of teeth that resembled pinking shears (serrated scissors commonly used for sewing). When the team looked at the teeth under a microscope they found a similar pattern of enamel and ridging, which they noted protected the teeth from wearing away. Instead, chewing served not only to crush food for consumption, but also sharpened teeth.The researchers suggest M. provincialis was a bipedal vegetarian—its big teeth would have allowed it to crunch even the toughest vegetation, including palm tree parts, which the team believes were abundant during the time M. provincialis was active. They also believe it was approximately 16 feet long and had a short face. Prior research has suggested the area where it was uncovered was once a tropical river system that was part of a flood plain—which explained the presence of palm trees, flying reptiles, turtles and crocodiles all living during the same time period. A team of researchers with members affiliated with several institutions in Belgium and France has identified the fossilized remains of a dinosaur from approximately 84 to 72 million years ago. In their paper published in the journal Scientific Reports, the group describes the dinosaur as a plant eater with teeth like self-sharpening pinking shears. Credit: Scientific Reports (2017). DOI: 10.1038/s41598-017-13160-2 © 2017 Phys.org Journal information: Scientific Reports Explore further More information: Pascal Godefroit et al. Extreme tooth enlargement in a new Late Cretaceous rhabdodontid dinosaur from Southern France, Scientific Reports (2017). DOI: 10.1038/s41598-017-13160-2AbstractRhabdodontidae is a successful clade of ornithopod dinosaurs, characteristic of Late Cretaceous continental faunas in Europe. A new rhabdodontid from the late Campanian, of southern France, Matheronodon provincialis gen. et sp. nov., is characterized by the extreme enlargement of both its maxillary and dentary teeth, correlated to a drastic reduction in the number of maxillary teeth (4 per generation in MMS/VBN-02-102). The interalveolar septa on the maxilla are alternately present or resorbed ventrally so as to be able to lodge such enlarged teeth. The rhabdodontid dentition and masticatory apparatus were adapted for producing a strict and powerful shearing action, resembling a pair of scissors. With their relatively simple dentition, contrasting with the sophisticated dental batteries in contemporary hadrosaurids, Matheronodon and other rhabdodontids are tentatively interpreted as specialized consumers of tough plant parts rich in sclerenchyma fibers, such as Sabalites and Pandanites. Citation: Fossil unearthed in France identified as a new vegetarian member of rhabdodontids (2017, October 27) retrieved 18 August 2019 from https://phys.org/news/2017-10-fossil-unearthed-france-vegetarian-member.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.
© 2017 Phys.org Explore further (Phys.org)—A team of researchers at Harvard University has developed a catalytic technique that allows for selecting a single enantiomer (mirror-image isomers) when choosing between one of two mirrored possibilities. In their paper published in the journal Science, the group describes their technique and the possible ways it might be used. Anita Mattson with Worcester Polytechnic Institute offers a Perspective piece on the work done by the team in the same journal issue along with a discussion of why such work is important. Citation: Using catalysts like tweezers to select single enantiomer from a mirrored pair (2017, November 10) retrieved 18 August 2019 from https://phys.org/news/2017-11-catalysts-tweezers-enantiomer-mirrored-pair.html As Mattson notes, using a catalyst to synthesize desired molecules has become a vital part of modern manufacturing processes—approximately 90 percent of all such reactions rely on a catalyst, she says. As she also notes, catalytic methods for creating chiral molecules in the form of mirror image isomers has also become very important in applications such as making pharmaceutical drugs or chemicals for use in agriculture. But, as she further notes, quite often, only one of the resultant molecules from the pair is desired (because they are not normally the same, biologically speaking)—thus, researchers require a means for selecting only the one that is needed. In this new effort, the team at Harvard has developed such a technique.In their approach, the team used molecular catalysts that had two closely set nitrogen-hydrogen groups as a sort of miniature tweezers, latching (by activating a carbon middle) onto a leaving group (using double hydrogen bonding) to pluck them away, leaving behind undesired material. The result was an ion pair that was biased to favor the one that was desired based on the shape of the catalyst. The group reports that they used their technique to set off a Lewis acid co-catalyst that pulled a leaving group off silicon rather than carbon. They suggest their technique is better for setting off reactions that involve weaker leaving groups on carbon. Mattson suggests that the new technique could be used by other researchers to help in the discovery of new catalyst combinations, perhaps leading to new complex molecular products. More information: Steven M. Banik et al. Lewis acid enhancement by hydrogen-bond donors for asymmetric catalysis, Science (2017). DOI: 10.1126/science.aao5894AbstractSmall-molecule dual hydrogen-bond (H-bond) donors such as ureas, thioureas, squaramides, and guanidinium ions enjoy widespread use as effective catalysts for promoting a variety of enantioselective reactions. However, these catalysts are only weakly acidic and therefore require highly reactive electrophilic substrates to be effective. We introduce here a mode of catalytic activity with chiral H-bond donors that enables enantioselective reactions of relatively unreactive electrophiles. Squaramides are shown to interact with silyl triflates by binding the triflate counterion to form a stable, yet highly Lewis acidic, complex. The silyl triflate-chiral squaramide combination promotes the generation of oxocarbenium intermediates from acetal substrates at low temperatures. Enantioselectivity in nucleophile additions to the cationic intermediates is then controlled through a network of noncovalent interactions between the squaramide catalyst and the oxocarbenium triflate. Journal information: Science Banik et al. show that a compound that makes hydrogen bonds to a Lewis acid creates an active catalyst. An example of a cycloaddition reaction is depicted. Tf, triflate; t-Bu, tert-butyl; Me, methyl; R, alkyl. Credit: (c) 2017 A. Kitterman/Science Using a nickel catalyst with hydrocarbons to make fatty acids 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.
Zee Entertainment Enterprises Limited (ZEEL), one of the country’s leading media and entertainment companies, on Wednesday announced the launch of a new television channel, Zee World, in Johannesburg.Zee World will be available from February 3 on DSTV channel 166. It is a general entertainment channel and is the first offering from ZEEL for mainstream viewers in Africa. The channel aims to showcase television series, Bollywood movies, reality shows and more action-packed content through the new channel. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cash”The corporate positioning of ‘Vasudhaiva Kutumbakam’ meaning ‘the world is my family’ is the driving force that enables us to bring authentic and entertaining content to global audiences, with a vision to reach a billion viewers by 2020,” Essel group and ZEEL chairman, Subhash Chandra said in a media statement. Speaking about the new channel, ZEEL chief executive officer – Middle East and Africa, Mukund Cairae said, “We will launch with four award winning series like Saloni, Laali, Married Again and The Promis.” Also Read – Lanka launches ambitious tourism programme to woo Indian tourists“The channel will also introduce other genres such as world drama series and shows on kids, food, reality and health before the end of the year 2015.” All content that will be aired has undergone extensive research and customisation including editing and dubbing with most of the channel’s content dubbed in South Africa using local talent. With a strong worldwide presence, boasting over 34 channels which entertains 730+ million viewers across 169 countries, ZEEL first ventured into Africa 18 years ago as the company’s first international territory.
Kolkata: In yet another horrific display of atrocity on minors, a Class IX student of a school in South Kolkata was found unconscious at Golf Garden area on Friday morning with injury marks on various parts of her body. She has been fighting for life at MR Bangur Hospital. She had gone missing while going to school on Thursday.Her school uniform was found torn and there were blood stains on her clothes. According to the circumstantial evidence, police suspect that the teenager might have been raped and also beaten up by the assailants. Also Read – Heavy rain hits traffic, flightsA woman, who was passing through a narrow lane near BD Memorial School on Friday morning to deliver newspapers, spotted the girl lying on the road. Her school bag was also found next to her, containing some clothes. The woman immediately drew the attention of the local residents, who rushed to the spot and took the victim to MR Bangur Hospital where she has been fighting for life. The doctors are examining to ascertain whether the girl was raped before she was thrashed and dumped on the road. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedPolice said that the narrow lane where the girl was found connects two residential apartments in the area and it often remains desolate. Police are also investigating to know when the assailants had dumped her on the lane.Local people alleged that she had been raped before being dumped on the lane. Police have recovered a locket and a chain from the place.Police were unable to record her statements as her condition has been stated to be serious. According to the police, the victim is a resident of Jadavpur and studies in a school in Tollygunge. She did not return home from school on Thursday afternoon. She was supposed to go to a private tuition class at Kalabagan area after returning. As she did not come home, her family members believed that she had gone to the tuition class directly from the school. As the victim did not return in the evening, her family members started a search operation. After failing to get any trace of her, they registered a complaint at the local police station at around 11 pm on Thursday.The family members told police that she had stepped out of the house at around 10 am on Thursday, for going to school. According to the preliminary investigation, police came to know that the victim did not go to school on Thursday. The investigators believe that she might have been abducted while going to school.Police are going through the CCTV footages in the nearby areas to identify the culprits. They suspect that she was dumped in the area in the wee hours of Friday. There were several injuries on her forehead and other parts. Police said that the girl used to live with her grandparents. The investigators are waiting for the medical report of the victim.