Scientists rediscover selfhealing silicone mechanism from the 1950s

first_img New nanotube material stays rubbery over a more than 1,000 degree temperature range The researchers, grad student Peiwen Zheng and Professor Thomas J. McCarthy from the University of Massachusetts, have published a paper on the rediscovery of siloxane equilibration in a recent issue of the Journal of the American Chemical Society.“We have been working on silicone materials from a couple of different perspectives,” Zheng told PhysOrg.com. “When we rediscovered the forgotten unusual properties of silicones and combined them with today’s research interests, we found that the silicone material with the siloxane equilibration was an obvious candidate for a self-healing material.”The researchers performed several experiments to test the theoretical predictions from papers published in the early 1950s, as well as to extend some of the experiments performed at that time. In one experiment, Zheng and McCarthy prepared a siloxane-based mixture containing a cross-linking agent and a catalyst. Then they poured the solution into molds of various shapes, such as cylinders, disks, and dog bones. After heating the molds at 90 °C (194 °F) for four hours, the researchers removed clear, rubbery silicone shapes from the molds. The scientists described these silicone samples as “living polymer networks.” More information: Peiwen Zheng and Thomas J. McCarthy. “A Surprise from 1954: Siloxane Equilibration Is a Simple, Robust, and Obvious Polymer Self-Healing Mechanism.” Journal of the American Chemical Society. DOI: 10.1021/ja2113257 (PhysOrg.com) — Research in self-healing organic polymers has grown recently, but one simple self-healing mechanism from more than 60 years ago has been nearly forgotten until now. Using this mechanism, which is called “siloxane equilibration,” scientists have demonstrated that silicone rubber that has been cut in half with a razor blade can completely repair itself through heat-activated reversible bonding. The self-healing mechanism could have applications in a variety of areas, such as for designing self-healing surfaces of vehicles and countertops. Citation: Scientists rediscover self-healing silicone mechanism from the 1950s (2012, January 30) retrieved 18 August 2019 from https://phys.org/news/2012-01-scientists-rediscover-self-healing-silicone-mechanism.html © 2011 PhysOrg.com (A) A silicone sample started off in the shape of a dog bone. (B) The sample was cut into pieces and rearranged in a dog mold. (C) The sample was remolded into a dog, in which the fracture locations are undetectable. Image credit: Zheng, et al. ©2012 American Chemical Society “The silicone network is at a chemically anionic equilibrium,” Zheng explained of the term, “where the reactive center will cleave and reform a covalent siloxane bond.” These bonds are reversible, which enables the two sides of a crack to reconnect under the right conditions.To demonstrate the self-healing ability, the researchers cut a 1-cm-long cylindrical sample in half using a razor blade. Then they rejoined the two pieces by wrapping them together with Teflon plumbing tape and heating them in an oven at 90 °C (194 °F) for 24 hours. When the researchers retrieved the sample and removed the tape, they found that the silicone cylinder had completely healed. Then they bent the cylinder by hand until it broke again – significantly, it broke in a different location than where it had been cut. The scientists repeated this experiment on different shaped objects with the same results. 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: Journal of the American Chemical Society In another experiment, the researchers molded a silicone dog bone, which they cut into multiple pieces. Then they rearranged the pieces to fit into a mold of a dog. Heating the sample resulted in a silicone dog with no visible fractures or weak spots where the pieces had been fitted together.The researchers also quantified the strength of the healed samples in comparison with the original samples using fracture toughness measurements. The data for the two types of samples was indistinguishable, indicating exceptional self-healing.The researchers explained that, in principle, any cross-linked dimethylsilicone elastomer (only one type was used here) can be converted into a living elastomer by the addition of basic catalysts. This possibility opens up many different routes for synthesizing a variety of self-healing silicione-based materials. While the samples used here required applied heating to self-heal, the researchers predict that samples in a sealed, high-temperature environment would self-heal “autonomically,” or automatically. Zheng explained that self-healing materials, with some improvements, could lead to a variety of applications.“It can be developed into self-healing coatings on auto vehicles or countertops,” she said. “It is also a ‘plastic’ elastomer which can be used in molding to form desired shapes and patterns. The concept of a self-healing silicone can be used to guide the preparation of elastomers with gradient modulus, Janus elastomers, reversible surface patterns when filled with magnetic particles, and super tough materials which can chemically relax stress.” Explore further (A) A silicone sample in the shape of a cylinder. (B) The sample was cut in half with a razor blade. (C) The sample completely self-healed after 24 hours at high temperatures. (D) When the healed sample was bent by hand, it broke in a different location than where it had been cut. Image credit: Zheng, et al. ©2012 American Chemical Societylast_img read more

Daedalus catches cyberattacks realtime

first_img NASA computer servers vulnerable to attack: audit According to a NICT video on DigInfo TV, “the sphere in the center represents the Internet, and the circles moving around it represent networks under observation. The state of an attack is shown using 3-D graphics, and can be viewed from any perspective.”Today’s cyber-attacks represent an assortment of malware via USB memory stick, mail attachments, and zero-day exploits. Daedalus can act as an alert system for the cyber-attacks; it can see if a USB flash drive with a virus infects a machine, for example. Daedalus can identify and isolate the malignant traffic on-screen, sending an email to support staff and displaying a red alert through its user interface.Further descriptions of an attack showing up realtime are provided in the video demo:”The blue part in this organization shows IP addresses that are used, and the black part shows addresses that are not used. This character indicates an alert. When you click on the alert, a message showing the cause appears. In this case, only two packets have been sent. But because the packets go from an address that’s used to an address that’s not used, this indicates that a virus is starting to spread within the organization.” The system sends out an alert, saying, ‘This IP address of yours is spreading a virus using this protocol at this time’.”Daedalus is designed to be used together with conventional systems, to improve network security within organizations. “We previously created a system called nicter for observing cyber-attacks. We also built an observation network in Japan, called the Darknet Observation Network, to cover IP addresses not used in nicter,” said a NICT source in the video. The nicter is a system for early detection and in-depth analysis of cyber-attacks. That word stands for Network Incident Analysis Center for Tactical Emergency Response. NICT is to provide Daedalus free of charge to educational institutions where nicter sensors can be installed. NICT will also transfer access to the system to Clwit, a company described as a Tokyo-based business providing Internet security countermeasures. According to reports, Clwit will develop it into the product, SiteVisor. Where administrators may have to comb through hundreds of lines of server logs to isolate a problem, the Daedalus system can reveal where attackers are focusing their flood of packets, as a stream of arrows moving along iridescent lines. Explore further More information: (Phys.org) — Japan’s National Institute of Information and Communications Technology (NICT) has developed a national cyber-attack alert system that can render network attacks as visible in realtime. The system, announced earlier this month and showcased at Interop Tokyo 2012, is called Daedalus, standing for Direct Alert Environment for Darknet and Livenet Unified Security. The system views computers for any suspicious activity and if it spots an attack it can visualize its progression as it moves through the network. It sees how data flows through the network and looks for inconsistencies. center_img © 2012 Phys.Org via Diginfo Citation: Daedalus catches cyber-attacks realtime (2012, June 20) retrieved 18 August 2019 from https://phys.org/news/2012-06-daedalus-cyber-attacks-realtime.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

Best of Last Week Map of universe questioned violent history of our

first_img(Phys.org) —It’s been a quirky week for physics as a study finds weird magic ingredient for quantum computing—a team of researchers with the University of Waterloo’s Institute for Quantum Computing found that an odd aspect of quantum theory called contextuality is a necessary resource to achieve what’s been described as the bit of magic needed for universal quantum computation. Also, map of the universe questioned: Dwarf galaxies don’t fit standard model—the mismatch is calling into question the standard model of cosmology, which no doubt has a lot of space scientists nervous. And who’d of thought that after years of geological study, that researchers would find new evidence for oceans of water deep in the Earth—beneath the United States, no less. In another bit of quirkiness, 55-year-old dark side of the Moon mystery is solved—turns out the lack of maria was due to a temperature gradient that came about as a result of the way our celestial partner was formed. © 2014 Phys.org Study finds weird magic ingredient for quantum computing Citation: Best of Last Week – Map of universe questioned, violent history of our faces and resistant bacteria found in food (2014, June 16) retrieved 18 August 2019 from https://phys.org/news/2014-06-week-universe-violent-history.html In completely unrelated news, a breakthrough of sorts has been achieved by a team of researchers at Penn State as they announce rescue of Alzheimer’s memory deficit achieved by reducing ‘excessive inhibition’—it’s not a cure, of course, but a promising new way of treating the disease. And a team at the University of Utah is wondering if our countenance evolved into the shapes we see today as a means of minimizing damage due to people punching each other in the face; they wonder did violence shape our faces? That might explain a lot.More practically, a team at Rice University has found a way to mimic the impressive skills of the Stenocara beetle—it pulls water out of morning fog and holds onto it for a long time—they’ve announced: nanotube forests drink water from arid air—modified carbon nanotubes that allow for harvesting water from the air for long-term storage.And finally, news that should have us all worried as antibiotic-resistant bacteria found in food products for the first time—a squid at a fish market in Canada was found to have Pseudomonas in it, not a particularly bad bug, but one that could get into the human gut and help much deadlier bacteria such as E. coli become resistant. Is the day coming sooner than we thought when we won’t have any useful antibiotics? Let’s hope not.center_img Explore further An EarthScope map illustrates the location of seismometers throughout North America. The EarthScope scientific community conducts multidisciplinary research across the Earth sciences utilizing freely available data from instruments that measure motions of the Earth’s surface, record seismic waves, and recover rock samples from depths at which earthquakes originate. 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

Study suggests fipronil caused massive honeybee dieoff in France

first_img Fipronil and imidacloprid reduce honeybee mitochondrial activity Credit: CC0 Public Domain Journal information: Proceedings of the National Academy of Sciences A team of researchers from the University of Exeter and Fera Science Ltd, both in the U.K. has found evidence that implicates the insecticide fipronil as the culprit behind a massive die-off of honeybees in France in the 1990s. In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of two insecticides that were thought to be behind the die-offs and what they found. Citation: Study suggests fipronil caused massive honeybee die-off in France (2018, December 4) retrieved 18 August 2019 from https://phys.org/news/2018-12-fipronil-massive-honeybee-die-off-france.html France experienced a serious die-off of honeybees over the years 1994 to 1998. The die-off, which was tied to colony collapse, began shortly after farmers began using two insecticides: imidacloprid and fipronil. Many farmers and some environmentalists blamed imidacloprid, but it was never proven to be the cause. Farmers stopped using both of the products and the die-offs stopped. In this new effort, the researchers have reviewed the die-off and report evidence that fipronil, not imidacloprid, actually caused the honeybee colony collapse and the subsequent die-off. To learn more about what actually happened, the researchers conducted mortality rate tests of the insecticides on honeybees in their lab and then set up simulations designed to show how the insecticides impacted the honeybees in the wild.The researchers report their simulations showed 4,000 to 9,000 more deaths compared to a control group over just the first week of exposure during testing of fipronil—colony collapse followed shortly thereafter. They also report that they ran a similar test with imidacloprid and it showed far fewer deaths and no colony collapse.The researchers also report that fipronil tended to bioaccumulate in the bodies of the bees while imidacloprid did not. Thus, prolonged or repeated exposure to fipronil was far more lethal. They suggest testing the impact of chemicals introduced into the environment for both mortality and bioaccumulation. They note further that because fipronil was never fingered as the cause of the die-off in France, insecticide makers around the world continue to use it to kill a variety of pests, likely putting bee populations at risk. Although fipronil is banned by the E.U., seeds treated with fipronil can still be sold across the continent.center_img Explore further © 2018 Science X Network More information: Philippa J. Holder et al. Fipronil pesticide as a suspect in historical mass mortalities of honey bees, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073/pnas.1804934115 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

Get a taste of the Seven Sisters in Delhi

first_imgPhysically, they are a world apart, and mostly neglected by what they call ‘mainland’. But the northeast of India is a dreamy land, yet to be explored. But Delhiites now have the chance to experience the Northeast first hand, right here in the Capital. And no, we are not talking of Dilli Haat.A mall in west Delhi has organised an exhibition in partnership with the National Skill Foundation of India. The  five-day exhibition has brought together the traditional crafts of the different states that are together called the Seven Sisters. All of these pieces are unique because they are handmade. You can pick up art, crafts, food items and even clothes from the states of Assam, Arunachal Pradesh, Meghalaya, Manipur, Mizoram, Nagaland and Tripura. Also Read – ‘Playing Jojo was emotionally exhausting’ A variety of organic horticulture products like orange pickles, organic honey, bamboo shoot products and Naga chilli can also be found here. Or pick up handwoven fabrics with symbolic ornamentation and the traditional saris of Assam, tribal ornaments made from cane and more. Bamboo products from Mizoram like handbags, baskets, flower vases, trays, hats and bamboo boxes are also being sold.The bamboo and cane have been procured from the forests of the Northeast and medically treated to increase longevity. One can also pick up eco-friendly products like bamboo carvings and bamboo furniture. Also Read – Leslie doing new comedy special with Netflix‘This exhibition has been organised with the aim of showcasing crafts, culture and products of the Northeast region. Such fairs not only bring the craftsmen into the limelight, but also provide an opportunity to the people to find out more about arts and crafts from another region,’ said Abhishek Bansal, ED, Pacific Malls.So get set to fill up your shopping bags.DETAILAt: Outer facade area, Pacific Mall, Rajouri GardenOn Till: 13 January Timings: 11 AM TO 9 PMlast_img read more

Panchayat poll hearing today

first_imgKolkata: The hearing in connection with the Panchayat poll process in Calcutta High Court is going to be held on Monday.Justice Subrata Talukdar had directed to stall all processes of the Panchayat election till April 16 and also directed the State Election Commission (SEC) to submit a detailed report on the measures it has taken to ensure peaceful filing of nominations.It may be mentioned that the hearing in the Division Bench of Justice Biswanath Somadder and Justice Arindam Mukherjee would also be held on Monday. Nilanjan Shandilya, SEC secretary, and Trinamool Congress Counsel and party MP Kalyan Banerjee made a plea before the Division Bench on Friday morning, seeking urgent hearing of their appeals in this connection.The BJP also moved a caveat before the Division Bench.The SEC had declared the dates of the Panchayat polls on March 31 and it was scheduled to take place in three phases on May 1, 3 and 5. Now, with the poll process being stalled till April 16, the entire state is now waiting for the hearing on Monday to know the decision on resumption of the poll process.last_img read more

TMC calls assistance to Bengal a bluff

first_imgWest Bengal’s ruling Trinamool Congress Saturday slammed the union budget, saying it was “not for the people”. The party also termed as “bluff” the special financial assistance to the state announced in the budget.“This budget is not for the people, not for the poor and not for the middle class. Lots of talk on giving more to the states, but this is untrue. Last year, gross output to states was 61.88 percent, this year it is 62,” Trinamool’s Rajya Sabha chief whip Derek O’Brien said.“There is a saying in Bengali: ‘Machher tele Machh Bhaja’ (Frying fish in fish oil). Only hollow talk on federalism. There is a lot of big talk on infrastructure and social development. Big promises… where are the action plan?” asked O’Brien.The party said the increase in service tax will hurt the middle class and lead to price rise of essential commodities.Dubbing the budget as “anti-people”, state Finance Minister Amit Mitra called the financial assistance to the state as announced by his union counterpart as “a bluff”.“There is a talk of a package in the lines of Andhra Pradesh, but we do not know the amount of package or any details.“The package to Andhra was Rs.850 crore. But the centre deducted Rs.28,000 crore from us towards servicing of debts. So this is a bluff,” said Mitra.Mitra also said if Prime Minister Narendra Modi agreed to meet, the Trinamool Congress would raise the issue of debt-structuring.Chief Minister Mamata Banerjee has sought an appointment with Modi to discuss the issue of moratorium of the debt which her government has been seeking since coming to power in 2011.“The total grant to the state in 2014 was Rs.4,05,582 crore and in this year, it is Rs.3,28,277 crore which is a reduction of 20 percent. The allocations for ICDS has been deducted by 50 percent, National Livelihood Mission decreased by 12 percent. Allocation for Sarva Siksha Abhiyan has been slashed by 22.14 percent,” said Mitra.last_img read more

Showcasing vehicles

first_imgAn annual rally of vintage automobiles, including motorised beauties with royal histories, organised by a private heritage trust may soon be scaled up with government backing to promote India as a preferred motoring tourism destination. This vintage car rally may ride on ‘Incredible India’ next year.“India had one of the largest numbers of these cars thanks to the maharajas and their love for automobiles. Events like these vintage rallies are a great opportunity to also promote India as a preferred motoring tourism destination, which is yet untapped,” said Suman Billa, Joint Secretary, Tourism Ministry. Also Read – ‘Playing Jojo was emotionally exhausting’“So, we are considering lending our logo and ‘Incredible India’ brand to this event, since through these platforms we seek to bring all like-minded stakeholders under one roof, which would eventually help in promoting tourism and conservation of such vintage automobiles,” says Billa.Madan Mohan, founder of the rally, which began in 2011, says, “125 hand-picked cars” from home and abroad will be the primary attraction of the rally, during which these beauties will be paraded from the Red Fort to the Buddha F1 Racing Circuit. Also Read – Leslie doing new comedy special with NetflixMohan who is also the Chairman and Managing Trustee of the 21 Gun Salute Heritage and Cultural Trust that helms the rally says cars both classic and royal —dating from period 1925 to 1950s besides 50 vintage motorbikes would be the cynosure of all eyes.“Another attraction would be a controlled speed racing on the Buddha Circuit. Two special Porsche cars, factory prototypes of 1950s vintage, brought from abroad, will race on it with full speed,” he says. “And, this year we have truly gone international, with cars coming to participate from countries like Nepal, Sri Lanka, the UK, the US, France, Germany, China, besides royal beauties that once adorned the stables of Maharajas in India,” adds Mohan. “Our idea of seeking support of the Tourism Ministry is also to promote India as a motoring tourism destination, which attracts huge number of tourists in some of the other countries,” he says.According to Billa, besides logo support, “the trust has also asked for some fund, we are looking into that as well. Though, we are yet to make it official, but we are also asking other states to come and participate in the rally next year.” The two-day vintage car rally is also set to feature a day-long cultural programme on February 6, showcasing the cultural heritage on the country in the various dance forms, from Bihu of Assam to Bharatnatyam of Tamil Nadu.“These Maharajas, besides being lovers of cars were also great patrons of arts and music, and therefore, it is only fitting to display the two heritage of the country together in a grand celebration,” says Billa. Some automobile beauties lined up to participate in the event include rare models like Bugatti Royale (France), Hispano-Suiza, Mercedes Benz, two Duesenberg from the US (one of which is owned by American comedian Jay Leno), all from the 1930s. A royal car that once belonged to the Dumraon Raj of Bihar, but now owned by proprietor of ‘Bombay Samachar’ Hormusji Cama, would also be part of the grand event.“This year, the focus is on quality of the cars and not numbers and we will present some of the rarest beauties, I can assure that,” says Mohan who commands an impressive fleet of over 250 cars, rare motorbikes, old phaetons, locomotives and even steam-driven road-rollers.“The tourism ministry believes in our vision and, if not millions but at least a few thousands or a lakh of tourists, we can think of attracting through this endeavour,” says Mohan.last_img read more

State declares holiday for Chhath Puja today

first_imgKolkata: The state government has declared a holiday on Tuesday for Chhath Puja and sectional holiday for the same on Wednesday. While addressing a gathering at the inaugural ceremony of Jagaddhatri Puja at Posta, Chief Minister Mamata Banerjee said: “The state government has declared holiday on Tuesday for Chhath Puja and there will be sectional holiday on Wednesday as well.” It may be mentioned that Banerjee will be attending a programme on the eve of Chhath Puja at Dahi Ghat in Kidderpore on Tuesday. It has been stated in the notification in connection with the holiday that “the state government has already declared holiday on November 13 for state government officers, boards, corporations, undertakings and educational institutions all over the state…In view of this, the Governor is pleased to further declare November 14 as sectional holiday for Chhath Puja.” People who perform Chhath Puja have appreciated the move. It may be mentioned that the state government has already issued a notification declaring holidays for the year 2019. There will be a holiday for 13 days at a stretch during Durga Puja. There will be an “additional day” holiday on February 11 for Saraswati Puja apart from the offices of the Registrar of Assurances, Kolkata, the Collector of Stamp Revenue, Kolkata and the West Bengal Beverages Corporation Limited.last_img read more

Apples iTunes brings in a new playlist for Bengali music lovers

first_imgSVF, East India’s largest entertainment company, has yet another reason to feel elated as Apple’s iTunes recently released its first ever Bengali music playlist, where all the songs are from SVF Music. The collection features 25 ultimate Bengali hits that will keep anyone hooked for two hours non-stop.iTunes’ Bengali Music features hits from films like Bolo Dugga Maiki, Yeti Obhijaan, One, Bojhena Shey Bojhena, Gangster, Besh Korechi Prem Korechi, Love Express, , Bindaas, Haripada Bandwala, Tomake Chai, Shona Bondhu, Zulfiqar and Yoddha. Some of the top artists featured are Arijit Singh, Shalmali Kholgade, Shreya Ghoshal, Vishal Dadlani, Shaan, Neha Kakkar, Anupam Roy and Jeet Gannguli, among others.Mahendra Soni, Co-Founder and Director, SVF, said, “We at SVF have the vision to put Bengali Film industry on the global map. It feels great that Apple’s iTunes, in its inaugural playlist dedicated to Bengali songs, has chosen all songs from the SVF music catalogue.”last_img read more