Materials scientist creates worlds toughest fiber by adding slip knot

first_img Journal information: arXiv Concept. The classical fibre dissipates during fracture its cumulated strain energy. In contrast, a fibre with a slider, e.g. knot, can dissipate much more energy, thanks to a sliding friction force. Credit: arXiv:1304.6658 [cond-mat.mtrl-sci] More information: The Egg of Columbus for making the world toughest fibres, arXiv:1304.6658 [cond-mat.mtrl-sci] arxiv.org/abs/1304.6658AbstractA great flourish of interest in the development of new high-strength and high-toughness materials is taking place in contemporary materials science, with the aim of surpassing the mechanical properties of commercial high-performance fibres. Recently, macroscopic buckypapers, nanotube bundles and graphene sheets have been manufactured. While their macroscopic strength remains 1-2 orders of magnitude lower than their theoretical strength, and is thus comparable to that of current commercial fibres, recent progress has been made in significantly increasing toughness. In particular, researchers have produced extremely tough nanotube fibres with toughness modulus values of up to 570 J/g, 870 J/g and very recently, including graphene, reaching 970 J/g, thus well surpassing that of spider silk (170 J/g, with a record for a giant riverine orb spider of 390 J/g and Kevlar (80 J/g). In this letter, thanks to a new paradigm based on structural mechanics rather than on materials science, we present the Egg of Columbus for making fibres with unprecedented toughness: a slider, in the simplest form just a knot, is introduced as smart frictional element to dissipate energy and in general to reshape the fibre constitutive law, showing evidence of a previously hidden toughness, strictly related to the specific strength of the material. The result is a nearly perfectly plastic constitutive law, with a shape mimicking that of spider silk. The proof of concept is experimentally realized making the world toughest fibre, increasing the toughness modulus of a commercial Endumax fibre from 44 J/g up to 1070 J/g. The maximal achievable toughness is expected for graphene, with an ideal value of 100000 J/g.via ArxivBlog Materials scientists describe a materials’ ability to take abuse in two ways: strength and toughness. Strength is measured by describing how much force it can support, while toughness is how much energy it can absorb before it breaks—hard brittle materials such as ceramics are strong, but not tough, while rubber is pretty tough, but not necessarily very strong. Pugno’s new slip knot technique—which he’s named Egg of Columbus—increases a material’s toughness, but not its strength—the underlying composition of the fiber isn’t changed—it’s more the way it’s arranged.To gain this new toughness, Pugno looked at the simple slipknot—it’s a kind of knot that grows tighter around an object when the rope used to make it is pulled. Pugno noticed that as a rope was pulled through other parts of the rope, friction occurred, slowing the pulling of the rope. When applied to single fibers, he found, the same principle caused the fiber to be able to absorb more energy than it would were it simply left as a single strand. Using this technique he was able to increase the toughness of Endumax—already the world’s toughest fiber—from 44 J/g up to 1070 J/g. Of course, because the material can only be pulled once, closing the slip knot, the increased toughness of the fiber is a single-shot deal.Pugno has also found that adding coils to the slip knots, just as is done with rope, can increase the amount of friction and therefore its toughness. In experimenting with different knots and coils, he’s also discovered that some work better on others and for that reason, is keeping this part of his research to himself, clearly believing there is money to be made from his fiber toughening technique.Of course, before that can happen, Pugno, or others will have to figure out if it’s possible to manufacturer fiber strands with tiny slip knots in them, in a cost effective manner. There’s likely to be millions of them in a single bullet-proof vest, for example. Citation: Materials scientist creates world’s toughest fiber by adding slip knot (2013, May 1) retrieved 18 August 2019 from https://phys.org/news/2013-05-materials-scientist-world-toughest-fiber.html © 2013 Phys.orgcenter_img Discovery yields supertough, strong nanofibers 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 (Phys.org) —Italian materials scientist Nicola Pugno has realized amazing gains in adding toughness to fibers by twisting them into slip knots resulting in materials that can take far more abuse before breaking than those currently in use. In his paper he’s uploaded to the preprint server arXiv, Pugno details how and why adding slip knots to fibers can make them much tougher.last_img read more

Researchers observe the competitive doublegamma nuclear decay

first_img Double gamma rays, denoted as γγ-gama rays, occur when two γ-rays are emitted as the excited quantum state of atomic nuclei decays, simultaneously, rather than the normal one at a time. The idea was first put forth by Maria Göppert-Mayer back in the late 1930’s. A decade later famed physicists Edward Teller and colleague Gregory Breit suggested that double-gamma nuclear decay was likely the mode at play during certain states of hydrogen, when single photon emission was not possible due to angular-momentum rules. It took forty more years for the rare process to be verified in the lab. In this new work, the researchers have succeeded in actually observing the process as it occurred with a barium nucleus.To make the observation, the team used an established means for detecting single γ-rays, but added five scintillation detectors and lead lining in the chamber to reduce scattering of the rays from one of the detectors to any of the others. Then, they ran the experiment for 50 days, taking measurements along the way. It was at that point that they finally received a verifiable (by being observed by more than one of the detectors at the same time) signal at the predicted energy levels, the first ever, though other teams have been trying for several years.In addition to serving as what Gade describes as an experimental tour de-force, the work likely will be used in the future to further study the nature of atomic nuclei. Next up is to find a way to measure the energy distribution of the γγ-gama rays. © 2015 Phys.org 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: Nature Citation: Researchers observe the competitive double-gamma nuclear decay (2015, October 15) retrieved 18 August 2019 from https://phys.org/news/2015-10-competitive-double-gamma-nuclear.html (Phys.org)—A team of researchers with Technische Universität Darmstadt, in Germany and an associate with the University of Saskatchewan in Canada has detected, for the first time, the double gamma decay of a nuclear quantum transition that vies with the allowed single γ-decay. In their paper published in the journal Nature, the team describes how they managed to capture the one in 487,805 chances phenomenon. Alexandra Gade with Michigan State University offers a News & Views piece on the work done by the team in the same journal issue, along with a brief history of the study and application of double-gamma nuclear decay. More information: Observation of the competitive double-gamma nuclear decay, Nature 526, 406–409 (15 October 2015) DOI: 10.1038/nature15543AbstractThe double-gamma (γγ)-decay of a quantum system in an excited state is a fundamental second-order process of quantum electrodynamics. In contrast to the well-known single-gamma (γ)-decay, the γγ-decay is characterized by the simultaneous emission of two γ quanta, each with a continuous energy spectrum. In nuclear physics, this exotic decay mode has only been observed for transitions between states with spin-parity quantum numbers Jπ = 0+. Single-gamma decays—the main experimental obstacle to observing the γγ-decay—are strictly forbidden for these 0+ 0+ transitions. Here we report the observation of the γγ-decay of an excited nuclear state (Jπ = 11/2−) that is directly competing with an allowed γ-decay (to ground state Jπ = 3/2+). The branching ratio of the competitive γγ-decay of the 11/2− isomer of 137Ba to the ground state relative to its single γ-decay was determined to be (2.05 ± 0.37) × 10−6. From the measured angular correlation and the shape of the energy spectra of the individual γ-rays, the contributing combinations of multipolarities of the γ radiation were determined. Transition matrix elements calculated using the quasiparticle–phonon model reproduce our measurements well. The γγ-decay rate gives access to so far unexplored important nuclear structure information, such as the generalized (off-diagonal) nuclear electric polarizabilities and magnetic susceptibilities. Researchers observe a new kind of disbandment in the atomic nuclei rich in protons Explore furtherlast_img read more

Delhi Book Fair to host discussions debates

first_imgSeminars, discussions, poetry sessions and interactive programmes for children will engage visitors at the 19th edition of the Delhi Book Fair that kickstarts in the Capital on Friday, organisers said.This year, the fair will address the erosion of the reading habit as its theme, Libraries and Readerships, will focus on the role of libraries in society. Organised since 1995 by the Federation of Indian Publishers (FIP) in collaboration with the India Trade Promotion Organisation (ITPO), the nine-day fair will attract over 250 participants from India and abroad. The fair ends 31 August. Also Read – ‘Playing Jojo was emotionally exhausting’Elaborating on the theme, Ashok Gupta, general secretary of FIP said, ‘Good libraries were once considered treasures of society. They were part of us, but today reading habits of people are going down. We wanted to raise this issue and so we decided to make it the theme of our fair.”The aim is to develop neighbourhood libraries. If people work in tandem, it is possible to start from the local area and have small library set-ups,’ he said. Apart from the national capital, that dominates the publishing industry, participation of publishers from Agartala, Andhra Pradesh, Jharkhand, Kerala, Maharashtra, and international participants from the US and China will mark their presence at this business-to-business event at Pragati Maidan in central Delhi.Other than displaying treasure troves of books from various genres, there will be discussion on Library and the Reader, poetry sessions, a seminar onTales for Today’s Children: Connecting to the Roots and an interactive programme for children Sune, Jane, Khele Kahani.There will also be a debate organised for university students, on Environmental Disaster caused due to Development of Vulnerable Hilly Areas.last_img read more

Pradhan calls on Pak Prime Minister

first_imgOil Minister Dharmendra Pradhan on Wednesday called on Pakistan Premier  Nawaz Sharif, who conveyed his warm regards to Prime Minister Narendra Modi.Pradhan, who is here to attend four-nation Turkmenistan -Afghanistan-Pakistan-India (TAPI) gas pipeline meet, met Sharif on the margins of the meeting along with other TAPI oil ministers. “PM Sharif conveyed his warm regards and best wishes to PM Narendra Modi,” an official statement said later. This is the first visit by any Indian minister here after the cancellation of Foreign Secretary-level talks between the two countries in August last year. India called off the talks after the Pakistan High Commissioner in New Delhi held consultations with the Kashmiri separatists on the eve of the Indo-Pak talks.Since then the ties between the two countries have been lukewarm. Even during the SAARC Summit in Nepal last year in November, PM Modi and his Pakistani counterpart only exchanged pleasantries briefly.last_img read more

SAT quashes Sebis ban on DLF by 21 majority Chair dissents

first_imgSebi’s orders imposing similar ban on DLF’s six top officials, including Chairman K P Singh and his children Rajiv Singh and Pia Singh, were also set aside by the same majority order, passed by two members of the SAT.The SAT Presiding Officer, J P Devadhar, however passed a separate ‘minority’ order, wherein he proposed reducing the ban from three years to six months.Amid an unprecedented argument between Presiding Officer and one of the Members, Devadhar pronounced another direction for staying the operation of the SAT order for a period of four weeks “in view of the conflicting views in the matter’, but another majority order by the two members again rejected Sebi’s plea for stay on the first ‘majority decision’. In its order dated October 10, 2014, Sebi had barred DLF and six others from the capital markets for three years, alleging “active and deliberate suppression of material facts” during its over Rs 9,000-crore IPO more than seven years ago. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cashWhile DLF has already gone through five months of debarment, the SAT order will help it tap the markets for raising necessary funds for business, including through REITs and mortgage-backed securities. Welcoming the order, DLF Executive Director Rajeev Talwar said that any further decision on fund raising from the markets would be taken after the company’s board is apprised of the matter by the legal counsel and experts. DLF shares soared higher by about 10 per cent immediately after the Sebi order was quashed by SAT. The stock finally closed with a gain of 6 per cent at Rs 157.5 at the BSE. Also Read – Lanka launches ambitious tourism programme to woo Indian touristsIn their strongly-worded majority order running into 85 pages, the two SAT Members — Jog Singh and A S Lamba — ruled that Sebi “has completely failed to approach the issue in the matter pragmatically. “Viewed from any angle, the impugned order is like a troubled sea whose waters only cast up mire and dust and, therefore, the same is liable to be quashed and set aside.”They also pulled up Sebi for lapses in its investigation into the case, while stating that it was the job of merchant bankers to ensure proper disclosures in IPO documents. The order also said DLF suffered huge losses, to the tune of thousands of crores of rupees, in its market value after Sebi’s ban, and therefore such directions could not be seen as those aimed at protecting the investors’ interest. Scrip towers by over 6%; MCap up by Rs1,524 crShares of DLF surged over 6 per cent, adding Rs1,524.36 crore to its market value, after the Securities Appellate Tribunal on Friday passed a ‘majority order’ quashing the three-year market ban imposed on the realty giant by regulator Sebi.The stock soared 5.74 per cent to settle at Rs 157.50 on the BSE. During the day, it surged 9.16 per cent to Rs 162.60. On the NSE, shares of DLF jumped 6.19 per cent to end at Rs 158.70. In the process, the company’s market value rose by Rs 1,524.36 crore to Rs 28,065.36 crore. In terms of volume, 39.94 lakh shares of the company changed hands at the BSE and over two crore shares were traded at the NSE.last_img read more

72 iron ore mines in Goa can resume operations Centre

first_imgThe state was getting almost a quarter of its revenue from the mining industry before it shut down in 2012.After deciding to revoke the suspension a few days ago, the ministry issued a formal order on Saturday, but made it clear that violation of mining lease conditions would lead to immediate suspension of ECs again.The licenses of these 72 mining leases have already been renewed by the state. The environmental clearances were suspended by the then Environment Minister Jayanthi Natarajan in September 2012 following allegations of rampant illegal mining and environmental degradation in Goa. Also Read – I-T issues 17-point checklist to trace unaccounted DeMO cashThe order says the ministry has decided to “lift the abeyance of the 72 leases and they would not require any fresh EC”. It has been signed by U Sridharan, scientist, MoEF.The state’s request to lift the abeyance was examined by the ministry, taking into account recommendations of expert appraisal committee and Supreme Court’s directions, it adds. However, suspension of ECs of 18 mines located in the one-kilometre buffer zone around wildlife sanctuaries has not been revoked. Further, there are 22 mining leases — named in a list attached to the order — on the forest land, and their ECs too would remain in abeyance until they get “forest clearances”.The ministry has directed the state to develop and implement a credible mechanism to ensure that “capping of 20 million tonnes per annum of ore extraction is implemented, as suggested by the apex court”. Mining in the forest areas and export of existing ore dumps would not be allowed, it adds.last_img read more

Musical tribute to the stalwart

first_imgA musical evening titled Tere Mere Darmiyaan, dedicated to Narayan das Jaju, was a treat for the city’s Ghazal lovers. The event was held at India Habitat Centre on Saturday. Several writers, bureaucrats and artistes attended the show that brought alive the works of Jaju.The programme featured a ghazal rendition by Shashank Shekhar, an accomplished singer and composer who was recently awarded the title of Aftaab-e-Ghazal, by the government of Telangana. Shekhar perfomed  Jaju’s popular ghazals. Also Read – ‘Playing Jojo was emotionally exhausting’The highlight of the concert was the use of classical raga by Shekhar in his rendition. There was a synergy between the words of Jaju and Shekhar’s voice which was heartily appreciated by the audience. Among the ghazals which impressed connoisseurs were — Arsa Hua Ke Mar Gaya, Andar Ka Aadmi,  Bheegi Raat, Bhari Barsaaten and Lautegi Ab Barsaat Liye, Teri Jhalak Bhi. Jaju, who passed away in 2012 at the age of 70, was a multi-faceted man. He was an avid traveller and voracious reader. However, he was a poet by heart and left behind an impressive body of work. He specialised in ghazals as well as Hindi poetry. His knowledge and understanding of Indian culture and ethos was remarkable which is well reflected in his writing. Jaju wanted peace and brotherhood in the country and wrote extensively about his vision of a just and fair society. Several collections of his poetry have been published in recent times.last_img read more

TMC hits back asks Shah to pay attention to BJPled central govt

first_imgKolkata: State Finance minister Amit Mitra launched a scathing attack on BJP calling it a party of militants that is threatening people and “killing” them to grab power.Comparing the saffron party to that of militants, Mitra said: “An Emergency-like situation has been created in the nation by the BJP. They have created fear among all over the country. Amit Shah who himself is a ‘dangi’ is talking about violence in Bengal. There is no discipline in their own party because they are a militant entity.” Also Read – Heavy rain hits traffic, flightsMitra came down heavily on Shah after he addressed the BJP’s rally in Purulia on Thursday.”But it is not that easy as the people of Bengal will build up protests against it as they had brought a mass leader in the name of Mamata Banerjee to power with a huge mandate,” Mitra said adding that the people of this country have rejected them for their lack of governance and their win in only one election out of 11 that was held recently has proved it.This comes when Shah claimed that the BJP will get more than 22 seats in the forthcoming Lok Sabha polls in Bengal. He maintained in the meeting: “Trinamool Congress chief is talking about the formation of Federal Front without realising that she is losing ground fast in Bengal.” Shah alleged that more than 2 crore people were not allowed to cast their votes in the Panchayat elections. “BJP has secured the second position in the elections and in 2021 it will oust Trinamool from Bengal.” Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedRubbishing Shah’s claims of improper utilisation of funds as the Finance Commission had given Rs 3.60 lakh crore to the Mamata Banerjee government, Mitra maintained: “He (Shah) is telling a blatant lie. If the money is not reaching the grassroot level then the people of Bengal would not have voted in favour of the Mamata Banerjee government. At the same time, the state has received several awards from the Centre itself just by carrying out development works.” It is the Centre that has stopped sanctioning funds for 38 projects and reduced its share for 28. The CAG has also mentioned that more than 30 to 35 percent of debt incurred by Bengal is spent for developmental activities. “But it is the Mamata Banerjee government that is somehow continuing with the project for the benefit of the people,” he said. Attacking Shah as a “communal face”, Mitra said: “They believe in the philosophy of dictatorship leading to repeated attacks on the federal structure of the country. They cannot win an election by dividing society.””The BJP doesn’t know the culture of the state and is talking about violence here at a time when people were killed in Uttar Pradesh, Kashmir and Madhya Pradesh in large numbers,” Mitra said adding that it is shameful that he is relating explosion of bombs to Rabindranath Tagore’s songs. This comes when Shah urged party workers to fight the terror that has been unleashed by the Trinamool Congress alleging that 20 party workers had been killed in the recently concluded Panchayat elections.last_img read more

EU scraps Greece summit with bailout deal on knifeedge

first_imgThe summit had been billed as a last chance to stop Greece crashing out, but was scrapped as euro-zone finance ministers returned today to marathon talks after failing overnight to overcome distrust with Greece’s leftist government.With Greece facing growing misery from capital controls and fears its banks could collapse within days, a meeting of the leaders of the 19 countries that use the euro was still due to go ahead in Brussels on Sunday.”I have cancelled EUCO (the European Union summit) today,” European Council President Donald Tusk tweeted. Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJI”Euro-summit to start at 1600 (1400 GMT) and last until we conclude talks on Greece.” The talks yesterday ended with deep divisions about whether to trust Greece’s radical Prime Minister Alexis Tsipras with a third bailout worth more than 80 billion euros (USD 89 billion), following months of wrangling.Fiscal hawks Germany floated a plan for a temporary “Grexit” from the euro while Finland reportedly decided flat out not to accept a new Greek rescue programme, causing panic. Also Read – Health remains key challenge in India’s development: KovindTheir downbeat assessment came despite Greece’s international creditors calling Athen’s new proposals a positive step forward after months of wrangling on a follow-up to two previous bailouts in 2010 and 2012 worth 240 billion euros.The proposals — including pension cuts and tax hikes that had been largely rejected by Greeks in a referendum a week ago — were approved by the Greek parliament in the early hours of Saturday.In Greece, there is growing alarm at capital controls that have closed banks and rationed cash at ATMs for nearly two weeks, leading to fears that food and medicine will soon run short. Economy Minister Giorgos Stathakis warned the restrictions will likely stay in place for “months” even if there is a deal.Greek newspapers expressed alarm, with the headline of the Eleftheros Typos in Athens saying: “The future of Greece on a razor’s edge” and asking “what will happen in the case of the nightmare of a Grexit?” The European Central Bank is providing emergency liquidity to keep Greek banks afloat but has frozen the limit, with fears that failure to reach a deal could cause it to shut off the taps completely.But a lack of trust in Greek authorities was blocking any agreement by the euro-zone ministers, who repeatedly called for further steps from Athens to show commitment to reforms.Italian Economy Minister Pier Carlo Padoan urged the Greek government to take steps as early as Monday to prove it would stick to its word.last_img read more

Bhangar imbroglio Final minutes between govt Committee likely by next week

first_imgKolkata: The “final minutes” between the state government and the Jomi, Jibika, Poribesh O Bastutantra Rakshya Committee over the implementation of the remaining work of the power grid sub-station in Bhangar is expected to take place by the next week. Most importantly, the work of the power grid sub-station will commence from the next day after the “final minutes” is signed.A senior state government official said: “Everybody is eagerly waiting for the meeting, in which the final minutes will be signed. It is hopefully going to take place in the next few days and all the stakeholders will abide by the same. They (senior members of the committee) are also discussing the matters with the people in the area to make them understand the need of the power grid sub-station there.” Also Read – Rain batters Kolkata, cripples normal lifeIt may be mentioned that a positive move with regards to bringing an end to the stalemate to set up the power grid sub-station has initiated, with the meeting held on June 23 between the representatives of committee and top brass of the South 24-Parganas district administration.They had placed some proposals before the district authorities and based on the same, necessary “modifications to the plan” was made to complete the remaining work of the power grid sub-station. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killed”The work of the power grid sub-station will be carried out as per the modified plan, to which they (committee representatives) have also agreed,” the official said, adding that there were certain misconceptions about setting up of the power grid sub-station. “It has been ironed out and the representatives of the committee are trying to make the villagers understand that the state government has accepted their proposals and the four towers need to be set up for completion of the project,” the official said. It may be mentioned that 90 percent of the power grid is complete and nine out of 13 towers have already been set up. Now, the remaining 10 percent needs to be completed and the remaining four towers will also be set up. Giving importance to the sentiment of local people, some modifications, including escalation of the height of the towers, would be brought.The steps to complete the work would be taken up the day after the “final minutes” is signed. Besides the top brass of the district authorities, senior officials of the state Power department would also be present when the final minutes will be signed.last_img read more