Friction almost vanishes in microscale graphite

first_img Explore further New method found for controlling conductivity Scientists first observed superlubricity in graphite in 2004, and so far all experimental evidence of superlubricity has been obtained on the nanoscale and under vacuum conditions. Previous research even predicted that superlubricity breaks down on larger scales. But now in a new study, scientists have demonstrated that superlubricity in graphite can occur over microscale areas and under ambient conditions, which could open the way toward practical applications in micromechanical systems.The researchers, led by Quanshui Zheng from Tsinghua University in Beijing and Nanchang University in Nanchang, China, and Jefferson Zhe Liu from Monash University in Clayton, Australia, have published their paper on the microscale superlubricity in graphite in a recent issue of Physical Review Letters.“We are providing evidence of superlubricity on a much larger scale than previously – micro rather than nano – and the effect persists even in ambient conditions,” Zheng told “We were not aware of the previous work predicting breakdown of the effect at the time the first measurements were done – perhaps that was fortunate, as it did not dissuade us from trying!”The most straightforward way to observe superlubricity is when two solid surfaces slide past each other. In the current study, the researchers developed a novel way of probing superlubricity by using a tungsten microtip to shear flakes from graphite slabs, or “mesas.” Upon release of shearing, some of the flakes spontaneously return to their original positions on the mesas, and this process of shearing and self-retraction can be repeated over and over. The scientists explained that the self-retraction results from ultralow friction that occurs between the flake and mesa surfaces when oriented in a twisted, or incommensurate, way. Citation: Friction almost vanishes in microscale graphite (2012, June 4) retrieved 18 August 2019 from (Top) Illustration of a mesa being partially sheared with a micromanipulator to form a self-retracting flake on a graphite platform. When the microtip is raised to release the flake, it automatically returns to its original position on the mesa. (Middle) Observation of this process in a vacuum in a SEM. (Bottom) Observation of the same process under ambient conditions with an optical microscope. Image credit: Liu, et al. ©2012 American Physical Society Although self-retracting flakes returned to their same positions and orientations as before shearing, the researchers could deliberately rotate sheared flakes before releasing them in order to create a commensurate orientation resulting in locked-in states, under which the flakes did not exhibit self-retraction. These locked-in states occur at some specific orientations exhibiting a 6-fold symmetry, but self-retraction still occurred when the mesas were sheared in all other directions.When investigating the flakes that did not self-retract, the researchers found abrupt variations in the color of the sheared flakes, while the color of self-retracting flakes was uniform. They think that the color variation occurs due to optical interference resulting from thickness variations in the graphite mesas. Larger mesas have larger thickness variations, as well as a smaller probability of exhibiting self-retraction.As the first evidence of reproducible superlubricity on the micron scale, and even under ambient conditions, the results could prove more useful for applications than superlubricity on the nanoscale. At the nanoscale, achieving superlubricity requires complex set-ups and sample preparation, and the effect can be easily suppressed by various mechanisms that cause twisting and lock-in. The new way of producing superlubricity on the microscale overcomes many of these barriers, and could be used to limit friction and wear in micromechanical systems. “There are many micromechanical devices – for example motion sensors, radio-frequency generators, gyroscopes – where the relative motion of two parts is important,” Liu said. “Superlubricity opens a new avenue for creating such devices.”The researchers plan to further explore the extent of superlubricity in the future.“We are already working on several fronts: to study the superlubric motion in more detail, to explore the extensions of this to both larger and smaller scales, and to study the long-term robustness of the effect under different physical conditions,” said coauthor Francois Grey of Tsinghua University. ( — In the phenomenon of superlubricity, two solid surfaces can slide past each other with almost no friction. The effect occurs when the solid surfaces have crystalline structures and their lattices are rotated in such a way as to cancel out the friction force. A bit like stacking two egg cartons, if the lattices are aligned, they lock in to each other and it is hard to slide one over the other. But rotate one egg carton a bit, and it no longer locks in this way. More information: Ze Liu, et al. “Observation of Microscale Superlubricity in Graphite.” PRL 108, 205503 (2012). DOI: 10.1103/PhysRevLett.108.205503 Copyright 2012 All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of 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 Letterslast_img read more

Persona Beta 2—identiy bridging solution—released by Mozilla

first_img Over time as Internet use has grown by a worldwide user community, the problem of maintaining multiple user accounts on various sites has grown to the extent that companies have now started creating solutions to solve the problem. Facebook Connect, and Google+ Sign-In are two prime examples—both allow users to sign in to websites users their respective web e-mail account information. But, both come with a caveat—using their bridging solutions means granting the respective host interactive rights with the website the user is trying to access. This, representatives at Mozilla say, is not something that users want—especially egregious is that it also allows the hosting site to track user activity across the Internet. Persona, they say, does neither and thus is a better choice for users. ( —Mozilla has released the second beta of its “Persona” identity bridging solution—offering users the possibility of a single login (e-mail address) and password for all of the sites they visit, or so the company claims. © 2013 Explore further Citation: Persona Beta 2—identiy bridging solution—released by Mozilla (2013, April 10) retrieved 18 August 2019 from More information: … 04/09/persona-beta2/ … sers-ready-to-log-in SplashData’s annual list shows people still using easy-to-guess passwords 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. The problem of multiple accounts has arisen as more websites have begun requiring users to log in to use their services. Such websites typically allow a user to pick a login name and password of their choosing and then use that information to track the user’s activity on their site. The problem comes in as users choose different login names or passwords for different sites and then have to remember them when it comes time to access the site. A better approach, bridging solution providers say, is for users to create a single account with a single source site, and then use that same login name and password to create user accounts on other web sites. In such cases, the norm is for the bridge service to use the web e-mail address as the login name. Thus, to log in to other websites that work with the bridge service, the user need only type in their e-mail address and the same password they use for that e-mail provider.In the case of Persona, Mozilla has forged a relationship with Yahoo—users can log into sites that support Persona using their regular Yahoo e-mail address and password. Mozilla reps outline all the security precautions they’ve put in place to ensure that hackers can’t access the stored e-mail addresses and passwords, but still don’t have an answer for users who want to know what happens if someone steals their password some other way and then finds that all of the websites they visit have been compromised en masse.last_img read more

Building block of thermal computer operates at 600 K

first_img Sidy Ndao and Mahmoud Elzouka, University of Nebraska-Lincoln College of Engineering, developed this thermal diode that may allow computers to use heat as an alternate energy source. Credit: Karl Vogel /University of Nebraska-Lincoln Engineering Illustration and scanning electron micrographs of the NanoThermoMechanical rectifier. Credit: Elzouka and Ndao. Published in Nature Scientific Reports. The entire device consists of 24 pairs of moving and fixed terminals, along with two thin-film platinum microheaters that independently control and measure the temperatures of each pair of terminals. When the fixed terminal is hotter than the moving terminal, the gap is large, resulting in a low heat transfer rate. When the moving terminal becomes hotter than the fixed terminal, the moving terminal moves closer to the fixed terminal and the gap decreases, leading to a higher heat transfer rate. At this scale, the heat transfer physically occurs due to a process called near-field thermal radiation, which results mainly from the tunneling of evanescent surface waves between two closely spaced surfaces. This demonstration is the first time that near-field thermal radiation has been used to operate a thermal diode at high temperatures. Doing this has been difficult due to the technical challenges in controlling the nanoscale gap.Tests showed that the thermal diode can operate at temperatures of up to 600 K, and the researchers expect that higher temperatures with improved performance are possible through design optimization. Another benefit of the method is that the thermal diode can be easily implemented, as it does not require exotic materials but instead uses standard techniques already known to the semiconductor industry. Explore further Journal information: Scientific Reports (—Researchers have built the hottest thermal diode to date, which operates at temperatures of more than 600 K (326 °C). Thermal diodes may serve as the building blocks of future thermal computers, which could run at temperatures at which today’s electronic computers would quickly overheat and stop working. The researchers, Assistant Professor Sidy Ndao and graduate student Mahmoud Elzouka at the University of Nebraska-Lincoln’s Department of Mechanical & Materials Engineering, have published a paper on the NanoThermoMechanical diode in a recent issue of Nature’s Scientific Reports.”We have demonstrated the building block of what could be the thermal computer of the future, and it works at very high temperatures,” Ndao told “For someone who also actively works in electronics cooling, it makes you wonder ‘What if we stopped cooling electronics all together?'”Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. A few examples include the exploration of planet Venus with average temperature over 400 °C, and deep-Earth drilling for petroleum and geothermal energies. Also equally important is the opportunity that this technology presents for waste heat recovery with the development of thermal batteries.”The function of a thermal diode is to allow heat to flow primarily in one direction but not the other, similar to how an electronic diode allows electric current to flow primarily in one direction. This ability to control the direction of flow enables diodes to produce two distinct levels of a signal, forming the basis for the “0” and “1” binary logic levels.The new thermal diode achieves two distinct levels of heat flow by controlling the distance between two surfaces: a moving terminal and a stationary terminal. The researchers showed that changing the relative temperatures of the two terminals changes the gap size between them, which changes the amount of heat transfer, which in turn depends on the direction of heat flow. Thermal memory thrives at extremely high temperatures More information: Mahmoud Elzouka and Sidy Ndao. “High Temperature Near-Field NanoThermoMechanical Rectification.” Scientific Reports. DOI: 10.1038/srep44901 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2017 Citation: Building block of thermal computer operates at 600 K (2017, April 3) retrieved 18 August 2019 from This is the first time that the relation among these four factors—temperature, separation gap, heat transfer rate, and heat flow direction—has been exploited for use in a thermal diode. last_img read more

Rock happens post show

Samant Chauhan called it a day post showing at the Wills Lifestyle India Fashion Week by getting together with friends from the fash frat at a yet-to-be-opened rock-themed restaurant in a Vasant Kunj mall. While many strolled in late after attending Manish Malhotra’s show, we spotted designers Charu Parasher, Nachiket Barve, Nitin Bal Chauhan, models Amit Ranjan, Sara, Lisa Verma, socialite Thenny Mejia, restaurateur Abhimanyu Rana among others raising a toast and letting their hair down. We got you a sneak peek.

Lightning kills 4 in state

first_imgKolkata: Four persons were killed due to lightning and one reportedly drowned as heavy rain lashed the state on Monday morning.With the prediction of “heavy to very heavy rainfall” in the next four days by the Alipore Meteorological Department, Chief Minister Mamata Banerjee has decided to cancel her Digha trip to monitor the situation from the state Secretariat.The heavy to very heavy rainfall has been predicted with further advancement of the south-west monsoon into most parts of Bengal. As per the prediction, there will be rainfall in Darjeeling, Jalpaiguri, Cooch Behar, Kalimpong and Alipurduar in North Bengal. East Midnapore, North and South 24-Parganas along with other districts in Gangetic Bengal will also receive heavy showers. Also Read – Heavy rain hits traffic, flightsThe Chief Minister was scheduled to hold an administrative review meeting of East Midnapore district in Digha apart from attending a public meeting. According to sources at Nabanna, the programme has been deferred for the time being.According to state government officials, four persons were killed due to lightning and one is feared drowned in Cooch Behar. Two persons died due to lightning in North 24-Parganas and one each in South 24-Parganas and Purulia. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedThe state Disaster Management and Civil Defense department has started taking necessary steps to ensure the safety of people. Authorities in all the districts have been directed to take measures regarding the same.Officials in the control room at the state Secretariat are keeping constant touch with the districts.Despite heavy rainfall in the city, the water receded quickly as the Kolkata Municipal Corporation (KMC) has already taken a series of steps to ensure that people do not suffer due to water-logging. There was 61.80 mm rainfall in Dhapa area while Topsia recorded the highest rainfall — around 82 mm. Places including Palmer Bridge, Ballygunge, Mominpur, Chetla and Jodhpur Park received rainfall between 58 mm and 71 mm. “In order to improve the situation further, the state government has allotted Rs 70 crore to carry out desiltation of drains at Dent Mission Row in Kidderpore. The matter related to water-logging near Science City has been discussed with Mayor Sovan Chatterjee. A project will be taken up soon to resolve the issue and the detailed project report (DPR) for the same will be ready by the first week of July”, said Tarak Singh, Member Mayor-in-Council (Drainage).With heavy rainfall since morning, movement of vehicles slowed down considerably. Traffic sergeants took necessary steps to keep vehicles moving.Fishermen have also been advised to be cautious while venturing into the sea as under the influence of moderate to strong south-west monsoon, there will be strong currents and the sea will be rough along and off Bengal coasts.last_img read more

IATO convention returns to MP after 22 years

first_imgPresident of Indian Association of Tour Operators (IATO), Subhash Goyal announced that the 31st IATO Annual Convention is going to be held in Indore, Madhya Pradesh from August 20-23. Goyal said, “We had several destinations in our mind and it was really difficult deciding on the venue. We had narrowed our search to Jammu and Kashmir, Tamil Nadu and Madhya Pradesh.”Sharma appealed to members to make the most of this national convention. He appreciated IATO’s efforts in promoting tourism and supporting the ministry in all it’s initiatives in tapping overseas markets. Also Read – ‘Playing Jojo was emotionally exhausting’Secretary, Ministry of Tourism, Lalit Panwar said that measures like e-tourist visa taken up by the government recently had started yielding results. He requested IATO members to give it wide publicity and encourage tourists to make use of this facility.Ashwani Lohani hailed IATO’s decision to hold its annual convention in Indore.  He also appealed to members to attend the convention in large numbers and attend the post convention tours especially being designed for the members. Also Read – Leslie doing new comedy special with NetflixMadhya Pradesh—home of Indian tiger, religious places like Mahakal temple in Ujjain, Buddhist stupa in Sanchi and the palace hotels in Bhopal, boating at Bheda Ghat and tourist spots in Jabalpur, Bhopal, Pachmarhi and Khajuraho are great attractions of the state. IATO Convention here will help Madhya Pradesh showcase its tourist potential even further,” said Lohani. “10th IATO convention was held at Khajuraho in 1993 and we are returning to Madhya Pradesh after nearly 22 years. Madhya Pradesh Tourism has been very active in marketing various tourists’ attractions in the state. With our convention, there will be Indian Travel Mart”, said Pronab Sarkar, IATO Chairman. “More than 1200 delegates are expected for the three-day event. They look for hitherto unexplored destinations”, said Sarab Jit Singh, Senior vice president, IATO.IATO also felicitated a 25-member delegation from Nepal headed by Ashok Pokharel, President, Nepal Association of Tour Operators (NATO) and also a Memorandum of Understanding (MoU) was signed between Indian Association of Tour Operators (IATO) and Association of Tour Operators of Andaman (ATO) for promotion of Tourism in Andaman.While concluding Goyal said that 10 top outbound tour operators from China selected by Air China are expected to attend the convention apart from tour operators from neighbouring countries like Nepal, Bangladesh, Bhutan and Sri Lanka.last_img read more

Scientists debunk happy drunk myth

first_imgThere may be no such thing as ‘happy drunk’, say scientists who have found that alcohol does not radically change personality.People typically report substantive changes to their personality when they become intoxicated, but observations from outsiders suggest less drastic differences between “sober” and “drunk” personalities, researchers said.”We were surprised to find such a discrepancy between drinkers’ perceptions of their own alcohol-induced personalities and how observers perceived them,” said Rachel Winograd of the University of Missouri, St Louis in the US. Also Read – Add new books to your shelf”Participants reported experiencing differences in all factors of the Five Factor Model of personality, but extraversion was the only factor robustly perceived to be different across participants in alcohol and sober conditions,” said Winograd.Researchers recruited 156 participants, who completed an initial survey gauging their typical alcohol consumption and their perceptions of their own “typical sober” personality and “typical drunk” personality. Later, the participants came to the lab in friend groups of three or four, where they administered a breathalyser test and measured the participants’ height and weight. Also Read – Over 2 hours screen time daily will make your kids impulsiveOver the course of about 15 minutes, each participant consumed beverages – some drank a soft drink, while others consumed individually-tailored vodka and soft drink cocktails designed to produce a blood alcohol content of about .09.After a 15-minute absorption period, the friends worked through a series of fun group activities – including discussion questions and logic puzzles – intended to elicit a variety of personality traits and behaviours. The participants then completed personality measures at two points during the lab session. And outside observers used video recordings to complete standardised assessments of each individual’s personality traits.Researchers found that participants’ ratings indicated change in all five of the major personality factors. After drinking, participants reported lower levels of conscientiousness, openness to experience, and agreeableness, and they reported higher levels of extraversion and emotional stability (the inverse of neuroticism). The observers, on the other hand, noted fewer differences across the sober and intoxicated participants’ personality traits. The observer ratings indicated reliable differences in only one personality factor: extraversion. Specifically, participants who had consumed alcohol were rated higher on three facets of extraversion: gregariousness, assertiveness, and levels of activity.last_img read more

Contact sports may alter brains of athletes

first_imgPeople who play contact sports such as football and hockey – that have higher risk of body collisions – are more likely show changes in their brain structure and function, a study has found. Researchers at St Michael’s Hospital in Canada performed preseason brain scans of 65 varsity athletes.They found that the athletes in collision and contact sports had differences in brain structure, function and chemical markers typically associated with brain injury, compared to athletes in non-contact sports.There is a growing concern about how participation in contact sports may affect the brain, said lead author Nathan Churchill, a post-doctoral fellow in St Michael’s Neuroscience Research Programme.Most of the research in this area has focused on the long-term effects for athletes in collision sports, such as football and ice hockey, where players may be exposed to hundreds of impacts in a single season.Less is known about the consequences of participating in contact sports where body-to-body contact is permitted, but is not purposeful, such as football, basketball and field hockey.This study looked at both men and women from a variety of sports, and found progressive differences between the brains of athletes in non-contact, contact and collision sports.This included differences in the structure of the brain’s white matter the fibre tracts that connect different parts of the brain and allow them to communicate with one another.Athletes in sports with higher levels of contact also showed signs of reduced communication between brain areas and decreased activity, particularly within areas involved in vision and motor function, compared to those in non-contact sports, such as volleyball.However, these differences do not reflect significantly impaired day-to-day functioning, said Tom Schweizer, head of the Neuroscience Research Programme. The study fills an important gap in understanding how contact affects healthy brains, as a step toward better understanding why a small number of athletes in contact sports show negative long-term health consequences.last_img read more