Physicists create carbon magnetism by removing atoms from graphite

first_imgUsing a homemade low-temperature scanning tunneling microscope, the scientists could identify the presence of a sharp resonance peak on top of individual vacancies. The resonance peaked around the Fermi level, which has been predicted in many theoretical studies but has never been experimentally observed before now.As the scientists explain, the resonance at a vacancy can be associated with a magnetic moment. The vacancies cause nearby electron spins to align due to repulsive electron-electron interactions, which leads to the formation of the magnetic moments. In addition, vacancies at different sites induce different kinds of magnetic moments, which can interact with each other. This interaction points to the possibility of inducing a macroscopic ferromagnetic state in the entire graphite material simply by removing random individual carbon atoms.“In a pristine carbon system, one would never expect to find magnetism because of the tendency of its electrons to couple in pairs by forming covalent bonds,” Brihuega explained. “The association of electrons in pairs runs against the existence of a net magnetic moment, since the total spin of the electronic bond will be zero. By removing one carbon atom from the graphite surface, what we do precisely is to break these covalent bonds and as a result we create a localized state with a single unpaired electron that will generate a magnetic moment.”Overall, the results not only confirm the accuracy of theoretical models, but also have further implications. For example, the observed resonances may enhance graphene’s chemical reactivity. In terms of applications, the results could lead to innovative magnets.“To create a magnet from a pure carbon system is a tantalizing possibility since this would be a metal-free magnet and thus optimal for applications in biomedicine,” Brihuega said. “In addition, it should be much cheaper to produce than conventional magnets since, to give some numbers, a ton of carbon costs around a thousand times less than a ton of nickel ($16 vs. $16,000), a commonly used material in actual magnets. In the case of graphene systems, one would also have flexibility and lightness as additional advantages; but to date, the total magnetization reported for these systems is very low when compared with the strongest existing magnets. “In my opinion,” he added, “the brightest future in terms of applications stems in the emerging field of spintronics, i.e. in trying to exploit the ‘spin’ of the unpaired electron for creating new spin-based devices.” (PhysOrg.com) — Physicists have found that, by removing individual atoms from a graphite surface, they can create local magnetic moments in the graphite. The discovery could lead to techniques to artificially create magnets that are nonmetallic and biocompatible, as well as cheaper and lighter than current magnets. Copyright 2010 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. How Perfect Can Graphene Be? 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 furtherlast_img read more

Researchers show how to use mobiles to spy on people

first_img Independent researcher Nick DePetrillo and security consultant Don Bailey demonstrated their system at the SOURCE Boston security conference earlier this week. Using information from the GSM network they could identify a mobile phone user’s location, and they showed how they could easily create dossiers on people’s lives and their behavior and business dealings. They also demonstrated how they were able to identify a government contractor for the US Department of Homeland Security through analyzing phone numbers and caller IDs.Bailey and DePetrillo’s demonstration showed up inherent weaknesses in the way mobile providers expose interfaces to each other to interoperate over the GSM infrastructure. They used the Home Location Registry (HLR) and GSM provider caller ID database, along with some of their own tools and voicemail-hacking techniques.Their technique was to first obtain their victim’s mobile phone number from the ID database, and they used an open-source PBX program to automate phone calls to themselves, which triggered the system to force a name lookup. They could then associate the name information with the phone number in the caller ID database. Their next step was to match the phone number with the location using HLR, which logs the whereabouts of numbers to allow networks to hand calls off to each other. Individual phones are logged to a register of mobile switching centers within specific geographic regions. DePetrillo said he was even able to watch a phone number moving to a different mobile switching center, regardless of where in the world they were located. The pair were even able to track a journalist who interviewed an informant in Serbia and then traveled back to Germany, and they also obtained the informant’s phone number. DePetrillo said it was also a simple matter to access voicemail without the phone ringing by making two almost simultaneous calls; the first disconnects before it is picked up, and the second goes into voicemail.The researchers have not released details of the tools they developed, and have alerted the major GSM carriers about their results. Bailey said the carriers were “very concerned,” but mitigating these sorts of attacks would not be easy. In the meantime there is little mobile phone users can do to protect themselves short of turning off their phones. Indications of an attack might include the phone calling itself, or the phone suddenly calling someone by itself, but most attacks would produce no signs visible to the phone user.DePetrillo said some of their research scared them, since they were able to track important people who were themselves protected by high security measures by tracking people close to them, such as congressional aides, who were not under high security. He also said the attacks they demonstrated could be made on corporations as well as individuals, and corporations would be well advised to look at the security policies they have in place, especially for their executives.Bailey said their system is not illegal and does not breach the terms of service. (PhysOrg.com) — Researchers have demonstrated how it is possible to use GSM (Global System for Mobile communications) data along with a few tools to track down a person’s mobile phone number and their location, and even listen in on calls and voicemail messages. Stop Big Brother listening in to your mobile phone conversation Citation: Researchers show how to use mobiles to spy on people (2010, April 22) retrieved 18 August 2019 from https://phys.org/news/2010-04-mobiles-spy-people.html © 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.last_img read more

Ford will sell solarpowered cars in partnership with panel vendors

center_img 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) — Ford has announced a partnership with San Jose-based solar panel vendor SunPower that will offer cars powered by rooftop solar panels. The panels will be installed by SunPower in the customer’s home, in a package deal priced at around $10,000. Prospective owners of the 2012 Ford Focus Electric can choose the solar option, to offset around 1,000 miles of driving a month. Ford will start producing an all-electric version of the Ford Focus later this year, and will sell it in California and New York this year. The wider rollout, to some 19 locations, will begin next year. The system will also be compatible with Ford’s plug-in hybrid C-MAX -Energi. via Ford press release Ford’s electric planslast_img read more

Researchers find researchers overestimate softscience results—US the worst offender

first_img Citation: Researchers find researchers overestimate soft-science results—US the worst offender (2013, August 27) retrieved 18 August 2019 from https://phys.org/news/2013-08-overestimate-soft-science-resultsus-worst.html More information: US studies may overestimate effect sizes in softer research, Published online before print August 26, 2013, DOI: 10.1073/pnas.1302997110AbstractMany biases affect scientific research, causing a waste of resources, posing a threat to human health, and hampering scientific progress. These problems are hypothesized to be worsened by lack of consensus on theories and methods, by selective publication processes, and by career systems too heavily oriented toward productivity, such as those adopted in the United States (US). Here, we extracted 1,174 primary outcomes appearing in 82 meta-analyses published in health-related biological and behavioral research sampled from the Web of Science categories Genetics & Heredity and Psychiatry and measured how individual results deviated from the overall summary effect size within their respective meta-analysis. We found that primary studies whose outcome included behavioral parameters were generally more likely to report extreme effects, and those with a corresponding author based in the US were more likely to deviate in the direction predicted by their experimental hypotheses, particularly when their outcome did not include additional biological parameters. Nonbehavioral studies showed no such “US effect” and were subject mainly to sampling variance and small-study effects, which were stronger for non-US countries. Although this latter finding could be interpreted as a publication bias against non-US authors, the US effect observed in behavioral research is unlikely to be generated by editorial biases. Behavioral studies have lower methodological consensus and higher noise, making US researchers potentially more likely to express an underlying propensity to report strong and significant findings. (Phys.org) —Researchers have found that authors of “soft science” research papers tend to overstate results more often than researchers in other fields. In their paper published in Proceedings of the National Academy of Sciences, Daniele Fanelli and John Ioannidis write that the worst offenders are in the United States. 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. Journal information: Proceedings of the National Academy of Sciences Soft drink consumption linked to behavioral problems in young children In the science community, soft research has come to mean research that is done in areas that are difficult to measure—behavioral science being the most well known. Science conducted on the ways people (or animals) respond in experiments is quite often difficult to reproduce or to describe in measureable terms. For this reason, the authors claim, research based on behavioral methodologies has been considered (for several decades) to be at higher risk of bias, than with other sciences. Such biases, they suggest, tend to lead to inflated claims of success.The problem Fanelli and Ioannidis suggest is that in soft science there are more “degrees of freedom”—researchers have more room to engineer experiments that will confirm what they already believe to be true. Thus, success in such sciences is defined as meeting expectations, rather than reaching a clearly defined goal or even discovering something new.The researchers came to these conclusions by locating and analyzing 82 recent meta-analyses (papers produced by researchers studying published research papers) in genetics and in psychiatry that covered 1,174 studies. Including genetics allowed the duo to compare soft science studies with hard science studies as well as those that were a combination of the two.In analyzing the data, the researchers found that researchers in the soft sciences tended to not only inflate their findings but to more often report that the outcome of their research matched their original assumptions. They also found that papers that listed researchers from the U.S. as leads tended to be the worst offenders. In their defense, the researchers suggest that the publish-or-perish atmosphere in the U.S. contributes to the problem as does difficulty in defining parameters of success in the soft sciences. The authors also noted that research efforts that included both hard and soft science were less likely than pure soft science efforts to lead to inflated results. © 2013 Phys.orglast_img read more

Using an organocatalyst to stereocontrol polymerization

first_img Explore further More information: A. J. Teator et al. Catalyst-controlled stereoselective cationic polymerization of vinyl ethers, Science (2019). DOI: 10.1126/science.aaw1703 Polymers are substances with a molecular structure that is generally made up of like units bound together—they are typically found in resins and plastics. In this new effort, the researchers endeavored to create a polymer that would have more adherence, making it more useful as a coating material. They noted that the two most popular polyolefins, polyethylene and polypropylene, do not adhere well because they are made of hydrogen and carbon—to become adhesive, they need oxygen. Prior research has shown that poly(vinyl ethers) (PVEs) can be made using free radical polymerization, but the results lack stereochemistry, which means they are not very strong or reliable. That led the researchers to devise a new approach that would allow catalyst control when making PVEs, which would give them well-defined stereochemistry using cationic polymerization. Stereochemistry refers to the three-dimensional arrangement of atoms that make up molecules and the impact that the arrangement has on chemical reactions.In their new approach, the researchers used an asymmetric phosphoric acid combined with a Lewis acid (titanium) to force the monomer into a desired orientation during ionic polymerization—the organocatalyst enabled the researchers to exert complete control over the resulting stereochemistry. The polymer they created was semi-crystalline, and testing showed it to be both strong mechanically (comparable to polyethylene) and highly adhesive.Foster and O’Reilly suggest the new approach could lead to the development of both adhesive coatings and medical devices. They also note that the new approach is scalable and amenable to various types of processing such as melting, molding and coloring. They also note that the concept behind the new approach appears to be transferable to other types of polymerization systems, which suggests a whole new class of products could be forthcoming. Designing a stereoselective cationic polymerization. (A) The chiral ligand environment in coordination-insertion polymerizations enables stereoselective monomer enchainment by directing facial addition at the propagating polymer chain end. Polar monomers are typically not compatible with this mechanism because of catalyst poisoning. Me, methyl. (B) The achiral chain end in the cationic polymerizations of vinyl ethers provides no inherent mode for stereoinduction. Monomer addition occurs at either face of the oxocarbenium ion. (C) Our catalyst-controlled approach to stereoselective cationic polymerization relies on a chiral, BINOL-based counterion to bias the stereochemistry of monomer enchainment. The resultant isotactic PVEs are semicrystalline thermoplastics with intrinsic polarity. Credit: Science (2019). DOI: 10.1126/science.aaw1703 Journal information: Science A pair of researchers at the University of North Carolina has developed a way to use an organocatalyst to stereocontrol polymerization. In their paper published in the journal Science, A. J. Teator and F. A. Leibfarth describe the process and outline some ways the results could be used. Jeffrey Foster and Rachel O’Reilly with the University of Birmingham have published a Perspectives piece on the work done by the team in the same journal issue.center_img © 2019 Science X Network An easy route to polymer coatings with potential use in biofouling prevention Citation: Using an organocatalyst to stereocontrol polymerization (2019, March 29) retrieved 18 August 2019 from https://phys.org/news/2019-03-organocatalyst-stereocontrol-polymerization.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

Depressed parents can turn kids into troublemakers

first_imgAccording to researchers, parental depression contributes to greater brain activity in areas linked to risk taking in adolescent children, leading to more rule-breaking behaviours.“This is the first evidence to show that parental depression influences children’s behaviour through the change in the adolescent’s brain,” said lead study author Yang Qu from University Of Illinois at Urbana-Champaign. There are a lot of changes happening in the teenage years, especially when we are thinking about risk-taking behaviours, added another researcher Eva Telzer. Also Read – ‘Playing Jojo was emotionally exhausting’The study, published in the journal Social Cognitive and Affective Neuroscience, analysed 23 adolescents aged 15 to 17, with cognitive testing and brain imaging at the beginning and end of the 18-month study. To measure parental depression, the team collected data from the parents on their own depressive symptoms and who were not currently being treated for clinical depression. The findings indicated that adolescents, whose parents had greater depressive symptoms, increased their risk-taking over the course of the study.last_img read more