Citation: Can quantum antiferromagnets reveal secrets of bosonic supersolids? (2008, March 13) retrieved 18 August 2019 from https://phys.org/news/2008-03-quantum-antiferromagnets-reveal-secrets-bosonic.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. “One of the fundamental issues in physics right now – and for the past many years – is whether or not bosons can form a supersolid phase,” Frédéric Mila tells PhysOrg.com. Mila is a scientist at the Institute of Theoretical Physics at École Polytechnique Fédérale in Lausanne Switzerland. “We show how a supersolid phase may be achieved in a quantum antiferromagnet.” Mila worked with Schmidt and Dorier, also at EPFL, and with Läuchli at the IRRMA in Lausanne on this project. Their work, which relies on a model of bosons with correlated hopping, is described in Physical Review Letters: “Supersolid Phase Induced by Correlated Hopping in Spin-1/2 Frustrated Quantum Magnets.”“One of the issues has been whether or not a boson system can simultaneously form a superfluid and a crystal at the same place,” Mila says. “Most of the work has been done with helium-4, but at this point it is still debated whether a supersolid phase can be realized. But,” he continues, “for bosons already on a lattice, it may be easier to make a superlattice and realize a supersolid which may be seen in nature.”In and email, Mila explains that one difference from the main approach to inducing a supersolid state in actual bosons (like helium-4) is to “deal with effective spin 1 triplet excitations induced by a magnetic field in certain quantum antiferromagnets, such as dimer models realized for instance in several copper oxides.”Indeed, these excitations behave like bosons – those particles, such as photons or pions, with integral or zero spin. “The analogy between bosons and quantum magnets has proven to be very fruitful during the past ten years,” Mila says, “and there is a one-to-one correspondence between spin supersolid and bosonic supersolid.”Additionally, Mila reports, the Lausanne team also made use of frustration in quantum magnets to induce correlated hopping between these bosons, whereby a boson can hop provided there is another boson nearby. This correlated hopping forms the basis of the model that Mila and his peers investigated: “Our paper shows that if bosonic triplets move through correlated hopping, the system will want to form a local solid order in order to gain kinetic energy,” Mila says, “thus realizing a spin supersolid”.Mila admits that right now this work is still speculative: “So far compelling evidences have not been detected in the best copper oxide candidate [SrCu2(BO3)2].” Mila points out that, “a supersolid is expected to undergo two phase transitions upon lowering the temperature where the two types of order develop, and only one has been reported in that compound. One cannot exclude that experiments were not performed at low enough temperature, but this could be due as well to anisotropy effects.”There is potential for future uses of bosons that could display two orders in the same system. “First of all,” Mila says, “experimentally and fundamentally it would be interesting.” But there are also possible materials applications. “As far as the future goes, there is general agreement that materials that could have two different types of orders at once would be interesting.” He is quick to qualify: “Of course, we are very far from any such applications.”For now, though, Mila is content to try and pursue the experimental route. “Our first interest is actually to convince experimentalists to look at quantum magnetism to see if there could be a supersolid phase.” Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.
The researchers have cut down these robotic creature-like drones to small size to what they call “nano-quadrotors.” The video shows them in action: not just engaged in formation flying, but also creating an impressive looking figure-eight pattern. Flying machines are YouTube sensation The video says as much about the GRASP Lab as the flying machines, in that the GRASP Labs seems intent on raising the bar on what robot swarms can achieve. Unfortunately, the video released is scant on technical detail.Still, the video is clear proof that the team developers, Alex Kushleyev, Daniel Mellinger, and Vijay Kumar, are able to showcase complex autonomous swarm behavior.The objects, in the words of Engadget, are “four-bladed aerial ninjas.” The announcer notes that the team has created “nano quadrotors capable of agile flight.”The key word is agile. Robotics enthusiasts blogging on their reactions to the video this week said they were impressed with the precision performance in formation flying, and, overall, in the swarm behavior of the nano quadrotors–aware of each other and of each individual’s place in space. Each “nano” device is self-sensing; each can position itself, keep its balance, and behave as a group member in carrying out maneuvers. GRASP stands for General Robotics, Automation, Sensing and Perception Laboratory. Its work integrates computer science, electrical engineering and mechanical engineering and involves students, research staff and faculty. GRASP’s nano-quadrotors are from the Lab’s “scalable sWarms of Autonomous Robots and Mobile Sensors” project. The project is working on new grouping skills in airborne robots. The researchers are trying to replicate swarming habits in nature. According to Vijay Kumar, a University of Pennsylvania professor and part of the team, explorations involve studying applications of biologically-inspired models of swarm behaviors to large networked groups of autonomously functioning vehicles. Scenarios that use the flying devices are imagined in military and natural disaster settings.“Can large numbers of autonomously functioning vehicles be reliably deployed in the form of a ‘swarm’ to carry out a prescribed mission and to respond as a group to high-level management commands? Can such a group successfully function in a potentially hostile environment, without a designated leader, with limited communications between its members, and/or with different and potentially dynamically changing “roles” for its members?”These are the questions posed by the Lab. According to the SWARM project site, “Military missions will rely on large, networked groups of small vehicles and sensors operating in dynamic, resource-constrained, adversarial environments. Groups of this type will typically operate with little or no direct human supervision and will be very difficult, if not impossible, to efficiently manage or control by programming or by tele-operation. Management of such large groups will thus be extremely challenging and will require the application of new, yet-to-be-developed methods of communication, control, computation and sensing, specifically tailored to the command and control of large-scale, autonomously functioning vehicle groups.” More information: www.swarms.org/ Explore further Citation: Airborne robot swarms are making complex moves (w/ video) (2012, February 2) retrieved 18 August 2019 from https://phys.org/news/2012-02-airborne-robot-swarms-complex-video.html (PhysOrg.com) — The GRASP Lab at the University of Pennsylvania this week released a video that shows their new look in GRASP Lab robotic flying devices. They are now showing flying devices with more complex behavior than before, in a fleet of flying devices that move in packs, navigate spaces with obstacles, flip over and retain position, and carry out formation flying, © 2011 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.
Explore further Evolutionary reason for massive difference in size between male and female giant moa revealed (Phys.org) —Until it became extinct in the 15th century, the moa, a flightless bird, played a significant role in New Zealand’s ecology. In a study published in the Proceedings of the National Academy of Sciences, Alan Cooper of the University of New South Wales in Sydney and his colleagues reveal they have used coprolites to reconstruct the dietary habits of four moa species. They determined how the moa’s extinction has affected New Zealand’s ecosystems and considered whether any existing species can take its place. Giant Haast’s eagle attacking New Zealand moa. Artwork: John Megahan. Copyright: PLoS Biology. Via Wikipedia. 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. More information: Resolving lost herbivore community structure using coprolites of four sympatric moa species (Aves: Dinornithiformes), PNAS, Published online before print September 30, 2013, DOI: 10.1073/pnas.1307700110 AbstractKnowledge of extinct herbivore community structuring is essential for assessing the wider ecological impacts of Quaternary extinctions and determining appropriate taxon substitutes for rewilding. Here, we demonstrate the potential for coprolite studies to progress beyond single-species diet reconstructions to resolving community-level detail. The moa (Aves: Dinornithiformes) of New Zealand are an intensively studied group of nine extinct herbivore species, yet many details of their diets and community structuring remain unresolved. We provide unique insights into these aspects of moa biology through analyses of a multispecies coprolite assemblage from a rock overhang in a montane river valley in southern New Zealand. Using ancient DNA (aDNA), we identified 51 coprolites, which included specimens from four sympatric moa species. Pollen, plant macrofossils, and plant aDNA from the coprolites chronicle the diets and habitat preferences of these large avian herbivores during the 400 y before their extinction (?1450 AD). We use the coprolite data to develop a paleoecological niche model in which moa species were partitioned based on both habitat (forest and valley-floor herbfield) and dietary preferences, the latter reflecting allometric relationships between body size, digestive efficiency, and nutritional requirements. Broad ecological niches occupied by South Island giant moa (Dinornis robustus) and upland moa (Megalapteryx didinus) may reflect sexual segregation and seasonal variation in habitat use, respectively. Our results show that moa lack extant ecological analogs, and their extinction represents an irreplaceable loss of function from New Zealand’s terrestrial ecosystems. Citation: Scientists use fossilized feces to reconstruct moa diet (2013, October 1) retrieved 18 August 2019 from https://phys.org/news/2013-10-scientists-fossilized-feces-reconstruct-moa.html © 2013 Phys.org Journal information: Proceedings of the National Academy of Sciences In the past 50,000 years, many large herbivores, which play an integral part in shaping vegetation communities, have become extinct. By analyzing fossilized feces, or coprolites, scientists can determine what these animals ate and gain a better understanding of the ecological impact of their extinctions. Cooper and his team chose to study the moa because it was the largest herbivore in New Zealand before humans arrived in the 13th century, and moa coprolites are relatively easy to find.The team examined 51 coprolites found at Daley’s Flat in the Dart River Valley in South Island. Radiocarbon dating and analysis of ancient DNA (aDNA) revealed that the coprolites belonged to at least 22 individuals of 4 different species: the South Island giant moa (Dinornis robustus), the upland moa (Megalapteryx didinus), the heavy-footed moa (Pachyornis elephantopus) and the little bush moa (Anomalopteryx didiformis). Before the moa became extinct, nine species lived on New Zealand. This is the first time scientists have been able to study more than one species at a single site.When the researchers examined fossilized plant materials, pollen and plant aDNA found in the coprolites, they found significant differences in the diets of the four species. They were able to create ecological models explaining how all four could coexist near Daley’s flat. While the bush moa found its food in the forests, the heavy-footed moa restricted itself to plants in open herb fields. The South Island giant moa and the upland Moa ate plants from both forests and fields. The South Island giant moa may have eaten low-quality fibrous plant matter that the other, smaller moas would not have been able to digest. The upland moa’s diet may have varied seasonally.The team believe the extinction of the South Island giant moa would have changed the forest canopy and understory, while the extinction of the shorter upland and bush moas would have affected the understory. The extinction of the heavy-footed moa would have caused the loss of herbs that depend on animals for seed dispersal. The researchers found that no living herbivore can fulfill all of these species’ ecological roles. The ecological changes stemming from their extinctions are irreversible.
© 2013 Phys.org A shot in the dark: Detector on the hunt for dark matter (Phys.org) —A mathematical scientist with the Isaac Newton Institute for Mathematical Sciences at the University of Cambridge, has proposed a possible way to test for the existence of axions—theoretical particles that might be possible components of dark matter. In his paper published in Physical Review Letters, Christian Beck suggests it might be possible to detect the existence of axions by using a Josephson junction. Citation: Mathematical scientist suggests possible test for existence of axions (2013, December 4) retrieved 18 August 2019 from https://phys.org/news/2013-12-mathematical-scientist-axions.html Credit: APS/Alan Stonebraker Explore further More information: Possible Resonance Effect of Axionic Dark Matter in Josephson Junctions, Phys. Rev. Lett. 111, 231801 (2013) prl.aps.org/abstract/PRL/v111/i23/e231801AbstractWe provide theoretical arguments that dark-matter axions from the galactic halo that pass through Earth may generate a small observable signal in resonant S/N/S Josephson junctions. The corresponding interaction process is based on the uniqueness of the gauge-invariant axion Josephson phase angle modulo 2π and is predicted to produce a small Shapiro steplike feature without externally applied microwave radiation when the Josephson frequency resonates with the axion mass. A resonance signal of so far unknown origin observed by C. Hoffmann et al. [ Phys. Rev. B 70 180503(R) (2004)] is consistent with our theory and can be interpreted in terms of an axion mass mac2=0.11 meV and a local galactic axionic dark-matter density of 0.05 GeV/cm3. We discuss future experimental checks to confirm the dark-matter nature of the observed signal. The existence of dark matter is still just theory, as no one has yet been able to detect its actual physical presence—all such evidence thus far has been circumstantial. Key to proving that dark matter exists is finding a particle that might form its basis. To that end, researchers have been trying for years to detect weakly interacting massive particles (WIMPs), or the much lighter axion. Thus far, hints of success have been found with WIMPs but no one has yet come close to seeing any evidence of the existence of an axion. In his paper, Beck suggests there might be a way to do so, and, it should be a relatively easy process, because it might have actually been done before without those responsible realizing it.Theory suggests, Beck notes, that an axion should be able to decay to a photon under certain circumstances and then revert back to its initial form. That suggests the opposite should be true as well. And if it did, it should be measurable via a release of an energy signal. He suggests that a Josephson junction (a junction made of regular metal sandwiched between two slices of superconducting material) might be a way to get the job done. The thinking is, if axions exist, they should be pouring down on us all the time, and if that is the case then they should in some cases decay to photons and revert back to form. If one happened to land on a Josephson junction, it might decay to a photon, pass through the sandwich and slip out the other side and then revert back to its natural axion state. And if that happened, it would have to leave behind a very small signal. And that is what’s got Beck so excited. Back in 2004 a team working with a Josephson junction recorded a slight signal that they could not explain—one that Beck says fits the properties of an axion.All that needs to happen now, he adds, is for someone to conduct experiments with Josephson junctions to see if they can reproduce the signal, and if so, prove that axions really do exist, and by extension, dark matter. 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. Journal information: Physical Review Letters
More information: Discovery of a Substellar Companion to the Nearby Debris Disk Host HR 2562, arXiv:1608.06660 [astro-ph.EP] arxiv.org/abs/1608.06660AbstractWe present the discovery of a brown dwarf companion to the debris disk host star HR 2562. This object, discovered with the Gemini Planet Imager (GPI), has a projected separation of 20.3±0.3 au (0.618±0.004″) from the star. With the high astrometric precision afforded by GPI, we have confirmed common proper motion of HR 2562B with the star with only a month time baseline between observations to more than 5σ. Spectral data in J, H, and K bands show morphological similarity to L/T transition objects. We assign a spectral type of L7±3 to HR 2562B, and derive a luminosity of log(Lbol/L⊙)=-4.62±0.12, corresponding to a mass of 30±15 MJup from evolutionary models at an estimated age of the system of 300-900 Myr. Although the uncertainty in the age of the host star is significant, the spectra and photometry exhibit several indications of youth for HR 2562B. The source has a position angle consistent with an orbit in the same plane as the debris disk recently resolved with Herschel. Additionally, it appears to be interior to the debris disk. Though the extent of the inner hole is currently too uncertain to place limits on the mass of HR 2562B, future observations of the disk with higher spatial resolution may be able to provide mass constraints. This is the first brown dwarf-mass object found to reside in the inner hole of a debris disk, offering the opportunity to search for evidence of formation above the deuterium burning limit in a circumstellar disk. © 2016 Phys.org Citation: Astronomers find a brown dwarf companion to a nearby debris disk host star (2016, August 26) retrieved 18 August 2019 from https://phys.org/news/2016-08-astronomers-brown-dwarf-companion-nearby.html Explore further Giant planet and brown dwarf discovered in a close binary system HD 87646 (Phys.org)—Astronomers have detected a brown dwarf orbiting HR 2562 – a nearby star known to host a debris disk. The newly discovered substellar companion is the first brown dwarf-mass object found to reside in the inner hole of a debris disk. The findings were presented in a paper published Aug. 23 on the arXiv pre-print server. 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. Collapsed datacubes showing HR 2562B in each of the four modes observed with GPI and reduced using KLIP. The K2 image is from February 2016 and demonstrates two possible solutions for the inner edge of the disk (38 and 75 AU with dashed and dotted-dashed lines respectively) assuming inclination of 78 degrees and position angle of 120 degrees. Credit: Konopacky et al., 2016. HR 2562, located some 110 light years away, is an F5V star, about 30 percent more massive than the sun. It has a debris disk—a circumstellar belt of dust and planetesimals left over from planetary formation. The disk around HR 2562, spans from 38 to 75 AU away from the host star.In January and February 2016, a team of researchers, led by Quinn Konopacky of the University of California, San Diego, observed HR 2562 using the Gemini Planet Imager (GPI), mounted on the Gemini South Telescope in Chile. GPI is a high-contrast imaging instrument, allowing imaging and integral field spectroscopy of extrasolar planets. The observations of HR 2562 were conducted as part of the Gemini Planet Imager Exoplanet Survey (GPIES), that images young Jupiters and debris disks around nearby stars.However, their search for a young, Jupiter-like planet resulted in a discovery of a much more massive substellar object. The data obtained during the observations, allowed the team to confirm the existence of a brown dwarf that could have at least 15 Jupiter masses. The newly found companion is separated by about 20 AU from the host star and was designated HR 2562B.”We present the discovery of a brown dwarf companion to the debris disk host star HR 2562. This object, discovered with the Gemini Planet Imager, has a projected separation of 20.3±0.3 AU from the star,” the researchers wrote in the paper.Separation by only 20 AU means that HR 2562B lies within the inner hole of the debris disk; significantly, it is the first known brown dwarf residing inside such a gap. The scientists also noted that so far, only few substellar companions have been imaged within 100 AU from their host stars.While the separation of HR 2562B has been precisely estimated, its mass remains uncertain. The scientists revealed that its minimum mass is at least 15 Jupiter masses. However, the brown dwarf could be even 45 times more massive than Jupiter as well. Thus, the mean value was calculated to be 30 Jupiter masses.Moreover, the host star’s age also remains to be determined, as previous observations delivered conflicting results, ranging from 20 million to even 1.6 billion years. However, for the purposes of the recent study, the team adopted a nominal age range of 300 to 900 million years.The findings published by Konopacky and her team, could be helpful to better understand the formation process of circumstellar companions; it is widely debated whether these objects form within a circumstellar disk and reach a mass above the deuterium burning limit or via cloud fragmentation, as in binary systems with a high mass ratio.The researchers concluded that future studies of the HR 2562 system should focus on constraining the true mass and orbit of the companion. It could be essential to determine its possible origin, which could offer evidence of planet formation above the deuterium burning limit.
Spanish astronomer Salvador Barquin has detected a new binary star system in the Draco constellation. The newly found system, registered by the discoverer in the International Variable Star Index (VSX), is an EW-type eclipsing binary. The finding is reported in a paper published May 16 on arXiv.org. Phase plot made with data from ASAS-SN Database for period P = 0.428988 days and epoch HJD 2457994.2756. Credit: Barquin et al., 2018. 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. More information: A New Binary Star System of EW Type in Draco: GSC 03905-01870, arXiv:1805.05797 [astro-ph.SR] arxiv.org/abs/1805.05797AbstractDiscovery of a new binary star system (GSC 03905-01870 = USNO-B1.0 1431-0327922 = UCAC4 716-059522) in the Draco constellation is presented. It was discovered during a search for previously unreported eclipsing binary stars through the ASAS-SN database. The shape of the light curve and its characteristics (period of 0.428988±0.000001 d, amplitude of 0.34±0.02 V Mag, primary minimum epoch HJD 2457994.2756±0.0002) indicates that the new variable star is an eclipsing binary of W Ursae Majoris type. I registered this variable star in The International Variable Star Index (VSX), its AAVSO UID is 000-BMP-891. Citation: Spanish astronomer discovers new binary star of EW type (2018, May 28) retrieved 18 August 2019 from https://phys.org/news/2018-05-spanish-astronomer-binary-star-ew.html EW-type eclipsing binaries (EWs) are W Ursae Majoris-type eclipsing variables with periods shorter than one day. They usually consist of two ellipsoidal dwarfs of spectral types F, G, or K that are in contact with each other, and share a common convective envelope lying between the inner and outer critical Roche-lobe surfaces.Although over 40,000 EWs are listed in the VSX catalog, astronomers are interested in finding new ones as the origin and evolution of such objects are still not fully understood. For instance, it is uncertain how eclipsing binaries of EW type form. Some studies suggests that third bodies may play an important role in the origin of EWs by removing angular momentum from the central binary through early dynamical interaction and later evolution.Recently, Barquin conducted a search for binary star systems by checking variability of chosen objects. For his search he selected an area within 200 arcseconds around one particular star in the Draco constellation known as TYC 3905-2030-1. By analyzing the available data regarding this region in ASAS-SN (All Sky Automated Survey for SuperNovae), Tycho-2 and UCAC4 (The fourth U.S. Naval Observatory CCD Astrograph Catalog) catalogs, he identified a new EW-type eclipsing binary.”It was discovered during a search for previously unreported eclipsing binary stars through the ASAS-SN database,” Barquin wrote in the paper.The astronomer found that the star designated UCAC4 716-059522 (also known as GSC 03905-01870 and USNO-B1.0 1431- 0327922) is variable and is not reported in the VSX database. According to the paper, the object has a period of 0.43 days, amplitude of 0.34 when it comes to magnitude in the V-band, and primary minimum epoch HJD 2457994.2756.Barquin concluded that these values indicate that UCAC4 716-059522 is an EW-type eclipsing binary.”The shape of the light curve and its characteristics (period of 0.428988±0.000001 d, amplitude of 0.34±0.02 V Mag, primary minimum epoch HJD 2457994.2756±0.0002) indicates that the new variable star is an eclipsing binary of W Ursae Majoris type,” the researcher wrote.Additionally, the author of the paper estimated the magnitudes of maximum (Max), primary minimum (Min I) and secondary minimum (Min II) of UCAC4 716-059522. These values are 14.43, 14.77 and 14.72 respectively.Barquin reported the newly found EW to VSX, providing all the necessary data including cross-identifications from existing catalogs. After its approval, UCAC4 716-059522 was assigned its AAVSO UID (American Association of Variable Star Observers Unique Identifier). Its identifier is 000-BMP-891. © 2018 Phys.org First early-type magnetic star in an eclipsing binary detected Explore further
Journal information: Science Ferroelectricity in perovskites is induced by discrete structural changes that occur at phase transitions. Credit: (c) C. Bickel/ Science (2018). DOI: 10.1126/science.aas9330 © 2018 Tech Xplore Ferroelectrics are materials that behave in a useful way—they become polarized when exposed to an electric current and remain in that state even after the electricity is removed. They are important, Li and Ji note, because they can be used as memory devices in electronic gadgets. Currently, most of the useful ones are inorganic perovskites (crystals that have the same structure as calcium titanium oxide). Unfortunately, manufacturing them has proven to be expensive—and because the process involves the use of heavy metals, they are also environmentally toxic. For that reason, scientists have been looking for ways to make perovskites without involving metals, i.e. organic perovskites. In this new effort, the researchers have developed a method to create 23 organic perovskites—one of which appears to be a good candidate to replace one of the most popular inorganic perovskites in use today: barium titanate (BTO).The researchers report that developing the new technique involved reacting a host of organic reagents with inorganic ammonium compounds and halogen acids. In so doing, they discovered that they were able to make organic perovskites that behaved in similar ways to inorganic perovskites. But perhaps most importantly, they found one, which they have named MDABCO, that has properties very similar to BTO, suggesting it might serve as a viable replacement. Li and Ji note that the organic perovskites are also soft, which means they respond differently to stress than traditional perovskites—a feature that should allow them to be grown in ways that BTO cannot, such as in thin films. This opens the door to new types of products and perhaps improvements in memory used in consumer devices. Additionally, the process also lends itself to lower manufacturing costs since they are so easy to synthesize, and are lighter than conventional ferroelectrics. Researchers report phase-stable inorganic halide perovskite A team of researchers at Southeast University in China has found a way to make metal-free perovskites in a useable form. In their paper published in the journal Science, the group describes their technique and how well it worked. Wei Li and Li-Jun Ji with Nankai University and Huazhong University respectively, offer a Perspective piece on the materials made by the team and explain why it is important, in the same journal issue. 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: A way to make cleaner metal-free perovskites at low cost (2018, July 13) retrieved 18 August 2019 from https://phys.org/news/2018-07-cleaner-metal-free-perovskites.html More information: H.-Y. Ye el al., “Metal-free three-dimensional perovskite ferroelectrics,” Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aas9330AbstractInorganic perovskite ferroelectrics are widely used in nonvolatile memory elements, capacitors, and sensors because of their excellent ferroelectric and other properties. Organic ferroelectrics are desirable for their mechanical flexibility, low weight, environmentally friendly processing, and low processing temperatures. Although almost a century has passed since the first ferroelectric, Rochelle salt, was discovered, examples of highly desirable organic perovskite ferroelectrics are lacking. We found a family of metal-free organic perovskite ferroelectrics with the characteristic three-dimensional structure, among which MDABCO (N-methyl-N’-diazabicyclo[2.2.2]octonium)–ammonium triiodide has a spontaneous polarization of 22 microcoulombs per square centimeter [close to that of barium titanate (BTO)], a high phase transition temperature of 448 kelvins (above that of BTO), and eight possible polarization directions. These attributes make it attractive for use in flexible devices, soft robotics, biomedical devices, and other applications. Explore further
A June noon is not the best time to drive to Satya Niketan from Chittaranjan Park. That is where Sri Venkateshwara College is, but I have sadly crossed that age when young men hang around colleges with hopes of getting lucky. So it had to be that other indulgence which middle age and midriff can’t take away. Food. Or in this case Dude Food.Now I have known the owner, Sumit Goyal, for some time now as food and lifestyle magazine editor. So I had to see for myself what he has done with his food joint. Food critics have taken preposterous decisions when they opened restaurants. I was hoping Goyal will be cleverer than them. He is. By keeping prices unbelievably low. Also Read – ‘Playing Jojo was emotionally exhausting’Dude Food is a small joint, tastefully done up with colourful chairs and shiny walls. With several colleges in the vicinity, it has the right feel to attract a young crowd. Even on a blistering hot weekday, we found all tables occupied. The other things that instantly sets Dude Food apart is the owner’s philosophy of ‘eradicating political correctness from Delhi’s food scene and wanting to offend anorexic and balanced critics paranoid of calorie count’. Dude Food is all about heavy eating and happy burps. Also Read – Leslie doing new comedy special with NetflixThere are interesting choices in the All Day Breakfast menu like the Dude omelette which is Spanish omelette with cheese served with sausage, bacon strips, grilled tomatoes, potatoes and roasted bread. But I have never heard of the Eggs Kejriwal before and given my interest in Aam Aadmi Party’s antics I had to order one. Goyal told me it is quite popular in Bombay and it is basically eggs, sunny side up with toasted bread and cheese. That done, I gorged on some Drunken Chicken (Chicken drums of heaven tossed in chilli garlic sauce and finished with dark rum) and gave in to my first happy burp of the day. But nothing compared to the massive ass Dude Beef Burger. It is as incorrect, politically and calorie wise, as it can possibly get with cheese, tomato, onion, lettuce, egg and smoked sticky bacon. I suggest you ask the good chef to cut it into two so that you don’t end up spilling it all over the table. This is pure heaven!There’s a lot more on offer. From salads and soups to burgers and pastas to shakes and smoothies. But that has to be another outing.As I tumbled out telling myself I will watch my diet for the next few days to offset what I just had, Rihanna crooned: Love the way you lie…