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Nanochemistry in Action

first_imgOverall the experiments showed how a nanoscale chemical reaction of cerium compounds can increase the conductivity of the surrounding carbon nanotubes. By using nanochemistry to controllably alter the nanotubes’ electric properties, researchers may be a step closer to using nanotubes for electronics applications.“Our nano test tube chemistry allows a clean, slow and defined growth of carbon nanotubes,” said Shiozawa. “Individual chemistry events can be observed at the elemental level when materials are confined within the nano test tube. This nanochemistry process can be applied for studying the growth mechanism of carbon nanotubes. Its conceptual advance would be for any chemical reactions in general. We showed that doping of the host carbon nanotube can be varied via encapsulations and chemical reactions of molecules. This process might be applied for modulating electrical properties of a SWCNT at the nanoscale and provides for better compatibility of carbon nanotubes with electronics.”Professor Ravi Silva, Director of the Advanced Technology Institute, added, “Our results are world-leading and will tell researchers and technologists working on the next generation of nanoelectronic devices some of the fundamental issues that must be taken into account in their design. We have shown that single atoms stuck on the surface of a carbon nanotube can have a tremendous effect on its electrical characteristics. The implications are widespread because these tubes are proposed to be used as wires in nano-scale integrated circuit chips within the next decade.”The study is published in a recent issue of Physical Review Letters, and the research was sponsored by a Portfolio Partnership award by the Engineering and Physical Sciences Research Council (EPSRC), UK.More information: H. Shiozawa, T. Pichler, C. Kramberger, M. Rümmeli, D. Batchelor, Z. Liu, K. Suenaga, H. Kataura, and S. R. P. Silva. Screening the missing electron: Nanochemistry in action, Physical Review Letters 102, 046804 (2009). link.aps.org/abstract/PRL/v102/e046804 Copyright 2009 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 This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Explore further In a recent study, a team of scientists from the UK, Austria, Germany and Japan have experimented with nano test tube chemistry by performing electron doping of carbon nanotubes using cerium compounds. Doping provides a promising means of tuning the nanotubes’ bulk electronic properties. In addition to helping scientists understand nanoscale chemistry, these experiments also highlight the potential of using nanotubes in future electronic devices.“We used nano test tube chemistry to functionalize the electronic properties of carbon nanotubes,” lead author of the study Hidetsugu Shiozawa of the University of Surrey told PhysOrg.com. “This allowed us to observe a fundamental physical phenomenon in bulk carbon nanotubes associated with a transition from semiconducting tubes to metallic.”In their experiments, the researchers sealed a combination of carbon nanotube material and cerium organometallic compounds in a Pyrex tube, and annealed them at temperatures of up to 200°C (392°F). After annealing, the researchers observed SWCNTs containing cerium molecules. Further annealing at 1000°C (1832°F) in vacuum allowed the researchers to transform the filled SWCNTs into double-walled carbon nanotubes containing cerium (Ce@DWCNT). The transmission electron micrographs show sharp lines, which are original nanotubes, inside of which are parallel lines and dark dots, which are inner tubes and cerium ions, respectively.The scientists were then able to extract electronic information from the cerium compounds in order to investigate the structures’ electronic properties. By measuring the energy of the emitted electrons using a method called resonance photoemission spectroscopy, the researchers found that the nanotube bundles had an increased density of conduction electrons after cerium doping, due to the transformation of the originally semiconducting nanotubes into metallic nanotubes.“When chemistry is performed in these nano test tubes, the reactions that occur get closer to a result of a single molecule reacting with another, instead of billions of molecules reacting with each other and with anything else we put into laboratory test tubes,” said Shiozawa. “The one-dimensionally quantized electronic states of carbon nanotubes allow specific molecules and compounds to interact, so we can monitor the encapsulated chemical reactions through the carbon nanotubes’ electronic states.” Citation: Nanochemistry in Action (2009, March 6) retrieved 18 August 2019 from https://phys.org/news/2009-03-nanochemistry-action.html (Left) An illustration of the conversion of encapsulated cerium molecules to an inner nanotube. (Right) A transmission electron micrograph of a double-walled nanotube containing cerium (Ce@DWCNT). Arrows point to cerium ions (dark dots) and lines (inner tube). Scale bar is 1 nm. Credit: H. Shiozawa, et al. ©2009 The American Physical Society.center_img In the active center of carbon dioxide conversion (PhysOrg.com) — Using a single-walled carbon nanotube (SWCNT) as a test tube, scientists can explore chemistry at the nanoscale, which involves some unique effects. Nanotubes provide a confined, one-dimensional space in which to isolate molecules, allowing nanoscale confinement effects to influence the chemical reactions. 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

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Researchers find soap film microchannel size tunable with electric charge

first_img Journal information: Physical Review Letters New rechargeable batteries needed: A microporous polymer is an unusually powerful supercapacitor In studying how fluids behave, scientists have found that when they move through a channel, free ions in them tend to stick to channel walls. Applying voltage to the ions causes them to move. That movement rubs the rest of the molecules causing them to move as well. The result is movement of a liquid through a channel due to an electric charge (electro-osmosis). Researchers have found that at the micro level, where the ratio of ions sticking to walls compared to the total amount of fluid is high, the process is particularly strong.In this new research, the team wondered what might happen if the channel walls were elastic. To find out, they created a soap film (essentially a bubble) between two electrodes separated by just half a centimeter. In this scenario, the soap film existed as two very thin, concentric cylinders of soapy material (water, surfactant and a small amount of potassium chloride to provide the free ions) with ions and water moving freely. Without a charge, gravity would cause the water molecules to fall towards the ground, eventually breaking the film (or popping the bubble). When given a small charge, however, the movement of the ions was sufficiently strong to keep the fluid moving throughout the film, and in some cases was actually strong enough to push it upwards. This was no surprise as other researchers had seen the same result. What was surprising however, was what happened when the voltage was increased.Prior research had suggested that increasing the voltage would cause the fluid movement rate to increase at a linear rate. Instead, they found the rate increased much faster than predicted. Upon closer inspection they found that this was due to the film becoming thicker, allowing for the movement of more liquid. This finding suggests it might be possible to create fluid micro-gates that can be fine tuned by adjusting the amount of electric charge and/or free ions, resulting in a type of micro-diode. More information: Soft Nanofluidic Transport in a Soap Film, Phys. Rev. Lett. 110, 054502 (2013) prl.aps.org/abstract/PRL/v110/i5/e054502AbstractWe investigate experimentally the electrokinetic properties of soft nanofluidic channels that consist in soap films with nanometric thickness, covered with charged surfactants. Both the electric and fluidic responses of the system are measured under an applied voltage drop along the film. The electric field is shown to induce an electro-osmotic hydrodynamic flow in the film. However, in contrast to systems confined between solid surfaces, the soft nature of the nanochannel results furthermore in a thickening of the film. This effect accordingly increases the total electro-osmotic flow rate, which behaves nonlinearly with the applied electric field. This behavior is rationalized in terms of an analogy with a Landau-Levich film withdrawn from a reservoir, with the driving velocity identified here with the electro-osmotic one.Featured on Physics Focus (Phys.org)—Researchers with Institut Lumière Matière, at the University of Lyon have found that soap film channels can be tuned using an electric charge to cause them to grow thicker or thinner on demand. In their paper published in Physical Review Letters, the team describes how they replaced a physical channel with one made of a thin soap film and found it was tunable due to its elastic walls. Explore furthercenter_img Voltage applied across this cylindrical soap film causes fluid to flow up against gravity in the roughly 100-nanometer-thick film. Credit: O. Bonhomme/Univ. of Lyon/CNRS, via Physics Focus © 2013 Phys.org Citation: Researchers find soap film micro-channel size tunable with electric charge (2013, February 7) retrieved 18 August 2019 from https://phys.org/news/2013-02-soap-micro-channel-size-tunable-electric.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

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Direct detection of nuclear transition in thorium229 hints at possibility of nuclear

first_img © 2016 Phys.org More information: Lars von der Wense et al. Direct detection of the 229Th nuclear clock transition, Nature (2016). DOI: 10.1038/nature17669AbstractToday’s most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of 229Th (denoted 229mTh). Here we report the direct detection of this nuclear state, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters. On the basis of this direct detection, the isomeric energy is constrained to between 6.3 and 18.3 electronvolts, and the half-life is found to be longer than 60 seconds for 229mTh2+. More precise determinations appear to be within reach, and would pave the way to the development of a nuclear frequency standard.Press release Journal information: Nature As Safronova notes, humans have always looked for new and better ways to keep track of time, which has led us from using the transition between night and day to the electronic transition in caesium atoms that today form the basis of atomic clocks which are capable of keeping time so precisely that they lose or gain a second only every 15 billion years. But still, scientists are not satisfied, many have suggested that creating clocks based on a nuclear transition from an excited state to a ground state, would be an order of magnitude more precise. The problem has been in figuring out how to measure such a transition—the only means possible today is to use a laser, but today’s laser are only capable of measuring the very slowest of transitions, which occurs with thorium-229—but even that has proven problematic, until now. In this new effort, the researchers report using a low-energy microchannel plate detection technique that ultimately led to electrons colliding with a phosphor screen, resulting in the generation of visible light which was captured by a camera. After extensive testing to ensure that the signals came from the decay of the thorium-229 instead of some other source, they team was ready to announce that they had found a way to detect a nuclear transition that could conceivably be used as a means for the basis of a nuclear based clock which could be as much as ten times more accurate than current atomic clocks.Such a clock Safronova, notes, could be used to test fundamental physics constants and even perhaps even dark matter, or as 3D gravity sensors or perhaps as part of an earthquake detection system. 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.center_img Schematic of the experimental setup. Credit: (c) Nature (2016). DOI: 10.1038/nature17669 Nuclear-atomic overlap for the isotope thorium-229 Citation: Direct detection of nuclear transition in thorium-229 hints at possibility of nuclear based clock (2016, May 5) retrieved 18 August 2019 from https://phys.org/news/2016-05-nuclear-transition-thorium-hints-possibility.html (Phys.org)—A group of researchers affiliated with several institutions in Germany has developed a means for the direct detection of the nuclear transition in thorium-229 which opens the door to the development of a clock even more accurate than an atomic clock—a nuclear based clock. In a paper published in the journal Nature, the researchers outline how they came up with their technique and the testing they carried out to ensure that the results they were getting were accurate. In a related News & Views piece in the same journal edition, Marianna Safronova, with the University of Delaware discuses the work done by the team, the likelihood that their work will lead to a nuclear based clock and the possible uses for such a clock if one could be developed.last_img read more

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Bones found in Romanera grave in London may be Asian

first_img Museum of London curator Dr. Rebecca Redfern with a skull from the Written in Bone display. Credit: Museum of London 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. Prior to this latest find, only one instance of the remains of a person from Asia has ever been found in a Roman era gravesite, suggesting there was little to no immigration between people in Asia and Europe during the Roman Empire, despite the existence of the Silk Road. The prior find was a skeleton of a man of East Asian ancestry discovered in a grave in Vagnari in Italy six years ago—and unlike the tests done with the newly found skeletons, his ancestry was proven by DNA testing.In this new finding, the two skeletons were part of a group of 22 skeletal remains found buried in an ancient Roman grave in Southwark, a London borough. The bones have been dated back to a period between the second and fourth centuries, a time during which the Roman Empire was still going strong. The researchers have thus far analyzed oxygen isotopes from the teeth and carbon and nitrogen isotopes from the bones—doing so has helped to reveal the eating and drinking habits of the people buried there, which showed that many of them were from places other than London.They also conducted statistical modeling of the skulls and teeth—differences have been attributed to people of different ancestries. It is the same technology used by forensic experts to establish the ancestry of decomposed skeletal remains. It was this testing that suggested that two of the skeletons were likely of Asian descent—and that four others were likely of North African descent. The researchers acknowledge that the method is not nearly as clear-cut as DNA testing, and in this case, it was even less so because many of the bones used in the analysis were fragmented. To actually prove that the bones had Asian ancestry, they will have to find some DNA to test. (Phys.org)—A small team of researchers with Durham University, the Museum of London and the British Geological Survey has tentatively established that two skeletons found in a Roman-era grave in London are of Asian origin. In their paper published in the Journal of Archaeological Science, the team describes the skeletons, the tests they conducted on them and why they believe they may be of Asian origin. Citation: Bones found in Roman-era grave in London may be Asian (2016, September 28) retrieved 18 August 2019 from https://phys.org/news/2016-09-bones-roman-era-grave-london-asian.html DNA testing on 2,000-year-old bones in Italy reveal East Asian ancestry Explore further Journal information: Journal of Archaeological Science More information: Rebecca C. Redfern et al, Going south of the river: A multidisciplinary analysis of ancestry, mobility and diet in a population from Roman Southwark, London, Journal of Archaeological Science (2016). DOI: 10.1016/j.jas.2016.07.016AbstractThis study investigated the ancestry, childhood residency and diet of 22 individuals buried at an A.D. 2nd and 4th century cemetery at Lant Street, in the southern burial area of Roman London. The possible presence of migrants was investigated using macromorphoscopics to assess ancestry, carbon and nitrogen isotopes to study diet, and oxygen isotopes to examine migration. Diets were found to be primarily C3-based with limited input of aquatic resources, in contrast to some other populations in Roman Britain and proximity to the River Thames. The skeletal morphology showed the likely African ancestry of four individuals, and Asian ancestry of two individuals, with oxygen isotopes indicating a circum-Mediterranean origin for five individuals. Our data suggests that the population of the southern suburb had an ongoing connection with immigrants, especially those from the southern Mediterranean. Credit: Museum of London © 2016 Phys.orglast_img read more

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Sweet sound of Bengal

first_imgMukherjee also performed her own composition on Matrivandana, which is an affluent of devotional songs with Sanskrit chants. Kolkata Doordarshan telecasted Matrivandana in last year during Durga Puja. With the requests of audience her scheduled performance for one hour was extended to approximately for two hours in Manchester. According to Bhattacharya, the organiser of Durga Mandir Trust of Manchester, ‘Rini is simply fantastic, everyone has liked her performance …she has enthralled the audience.’ He further added that  ‘Our divine mother binds the entire community with peace and harmony. In order to promote, serve and benefit the inhabitants of Greater Manchester and neighbouring areas, and to stimulate public consciousness on our rich cultural heritage, our vision is to have our own building with a community centre to organise Social, Cultural, Religious and Educational activities.’ Also Read – ‘Playing Jojo was emotionally exhausting’Mukherjee has also performed in Belsize Park, Wimbledon and Uptron Park. With her versatility, she presented Bengali and Hindi Rabindra Sangeet and folks, Nazrul Geeti, melodies of Lata Mangeshkar and Asha Bhosle both  in Hindi and Bengali. Banerjee the organiser of  Bengali Cultural Association, London mentioned that, ‘She has got very powerful voice’. According to Ghosal, a veteran member of the puja committee,  ‘At this age, her beautiful voice and sense of rhythm has compelled us to dance and looks that our age has gone back by ten years.’last_img read more

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Fun another day

first_imgDiwali is over, but it doesn’t mean you should stop the festivities. Dilli Haat Utsav, the signature festival of Delhi Tourism is back with its sixth weekend for a post-festive cultural dose. This series of cultural events that started on 13 September,  under the banner of Dilli Haat Utsav, are scheduled to continue till 31 March, 2015.Different institutions under Department of Art, Culture and Languages, like Punjabi Academy, Hindi Academy, Sanskrit Academy, Sahitya Kala Parishad etc. are showcasing their unique creations through artistic expression of dance and music. Also Read – ‘Playing Jojo was emotionally exhausting’With a first of its kind unique initiative, Dilli Haat Utsav has given an organised platform to different artistes for presenting their talent and gathering accolades. In the past weekends, Dilli Haat Utsav has attracted large number of people to their nearest Dilli Haat to witness the action unfold and this weekend is also packed with exquisitely colourful and vibrant presentations. The celebrations never end at Dilli Haats. Under the Delhi Haat Utsav, Dilli Haat Janak Puri and Urdu Academy will present a special gazal presentation by Fareed Ahmed Khan on Saturday and Javed Khan on Sunday. Also Read – Leslie doing new comedy special with NetflixThe INA Dilli Haat on the other hand, is all set with a live music band performance comprising gazals, utsav sangeet and sufiana music by Sakha Creation on Saturday. This will be in association with Hindi Academy. Himalya Art will be showcasing the cultural diversity of India through instrumental music, singing and diverse folk dance performances on Sunday.At the Dilli Haat Pitampura,  artistes  from the Sahitya Kala Parishad will captivate the audience with their craft. Jai Mala Group and Veena Vyas will be performing folk dance on Saturday and Sunday respectively.Besides this, the visitors will have food from numerous diverse Indian cuisines on their platter. The handloom and handicraft stalls at all Dilli Haats exalt authentic goods, which reaches the buyer directly, bypassing the middlemen nexus.last_img read more

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Revised Met forecast sparks drought fears

first_imgWhile releasing the second stage long range forecast of monsoon, Union Minister for Earth Sciences Harsh Vardhan said that the rain will be 88 per cent instead of 93 per cent of earlier forecast.In its current update, IMD says there is about 90 per cent probability of El Niño conditions prevailing during the south-west monsoon season. El Niño conditions are likely to strengthen further and reach moderate strength during the monsoon season. Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJI “For 2015, the IMD’s prediction of an overall 93 per cent probability of a weak monsoon is a worrying cause for all of us. The onset has been delayed by a week already and there is no certainty on when the monsoon will arrive,” Vardhan said, while dedicating the country’s high performance computing (HPC) facility – Bhaskara.However, talking to Millennium Post, Union Agriculture Minister Radha Mohan Singh said: “There is nothing to panic about it. The government is ready to tackle the drought-like situation if it happens due to deficient rain.” Also Read – Health remains key challenge in India’s development: Kovind“Given the fact that about 60 per cent of the country’s cultivable land is rain-fed and low rain will directly hit the farm sector. The monsoon is considered below normal when the rainfall range is 90-96 per cent of LPA and is considered deficient if it falls below 90,” an India Meteorological Department (IMD) official said.In its earlier forecast released in April, IMD had said that monsoon rain is likely to be 93 per cent of LPA. The main reason for the subdued forecast is fear of the onset of El Niño weather phenomenon – the warming of the waters of the Pacific Ocean, which triggers atmospheric changes that influence the progress of monsoon rains over India.last_img read more

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SC to hear in open court pleas to review verdict on govt

first_imgThe Supreme Court on Tuesday agreed to hear in open court a batch of petitions seeking review of its landmark judgement barring publication of photos of leaders in official advertisements except those of the President, Prime Minister and the Chief Justice of India.“Application for hearing in open Court is allowed,” a bench comprising Justices Ranjan Gogoi and Pinaki Chandra Ghose said. The bench passed the order after considering the pleas of various states governments in its chamber proceedings. The bench said all the petitions seeking review of the verdict will be tagged and heard together. It had on September 14 issued notice to the centre and the NGO Common Cause, which had filed the original PIL, on review petitions filed by the states. Uttar Pradesh, Tamil Nadu, Karnataka, West Bengal and Assam had also moved the apex court seeking its nod to publish photographs of Chief Ministers on their advertisements.Recently, the apex court had sought response from Centre as to whether it has set up a three-member ombudsman to regulate advertisements issued by various governments and authorities.last_img read more

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WBTC bus catches fire near Jessore Road none hurt

first_imgKolkata: A West Bengal Transport Corporation (WBTC) bus caught fire on Wednesday morning on Jessore Road near airport 2 1/2 number gate. Passengers were immediately evacuated and the fire spread all over the bus within minutes. Later, two fire tender doused the flames within half an hour. No casualty was reported.According to the sources, around 11:25 am on Wednesday, a WBTC C-23 bus of Dankuni-Park Circus route was approaching Jessore Road from Belgharia Expressway. At the end of Belgharia Expressway Flyover, some passengers got a burning smell and noticed smoke billowing out from Also Read – Rain batters Kolkata, cripples normal lifethe engine. On seeing smoke spreading inside the bus, the passengers got panic-stricken and started screaming. The driver immediately stopped the bus and asked the passengers to abandon it. Just after the passengers got down, the flames spread all over the bus standing in the middle of the road. All the airport-bound vehicles were stopped at airport gate number 3. Police rushed to the spot and arranged for a pipe. Though Traffic Inspector (TI), Airport, Sushanta Mondal tried to douse the flames but failed as the water pressure was not enough. However, the fire did not spread more. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedMeanwhile, two fire tenders reached the spot and controlled the fire within a short period of time. On seeing a bus on fire, traffic police personnel rushed to the spot. The fire brigade was also informed. One fire tender was pressed in to action. Traffic movement towards airport 1 number crossing was completely stopped. As a result, the congestion touched the Michel Nagar. The fire was completely doused around 12:20 pm. The bus was then towed away to Airport police station and vehicular movement was resumed. It is suspected that the fire occurred due to a mechanical glitch. Sources informed that forensic experts will examine the bus to identify the reason behind the incident.last_img read more

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Dead puppies KMC writes to NRS chief Entally police to conduct impartial

first_imgKolkata: The Kolkata Municipal Corporation (KMC) has taken a serious note of the incident where a garbage bag containing 16 dead puppies was found inside the campus of NRS hospital and written to the hospital superintendent and Entally police station to conduct an impartial probe into the matter and take strong steps against those who would be found guilty in the offence.”We have written to the superintendent of the hospital mentioning if somebody associated with the hospital is found involved in the matter then they should not be spared,” said Deputy Mayor Atin Ghosh, who oversees the Health wing of the KMC. Also Read – 3 injured, flight, train services hit as rains lash BengalGhosh on Monday sent two teams to the hospital to take measures in sterilising or vaccinating stray dogs as per need to prevent rabies and also control the birth of animals. As per laws of animal conservation, the KMC cannot take away dogs to other places but they can sterilise or register anti-rabies vaccine to the animals. “We usually do not enter into institutions of health or other sectors on our own for vaccination of animals. But whenever they seek help from us, our team reaches there and after vaccination or sterilization, we drop them at the same place,” an official of the KMC’s health wing said. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedThe KMC has sterilised about 7,800 dogs and registered anti-rabies vaccine to 25,000 animals by holding two camps each in every ward till January 6. “Our fresh programme in this regard will start from March,” Ghosh said. According to him, the steps taken have helped in preventing proliferation of the population and lessened the cases of rabies. The entire event has been conducted with the funds provided by the state Animal Husbandry department.last_img read more

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