© 2010 PhysOrg.com A team of scientists, Fei-Fei Cao, et al., from institutions in China and Germany, have found that applying a thin coat of TiO2 to the outside of carbon nanotubes (CNTs) can create coaxial nanocables. The nanocables can then be formed into a crystalline solid that turns out to be very good at trapping lithium ions and quickly transporting electrons – much better than either TiO2 or CNTs on their own.“On one hand, the CNT core provides sufficient electrons for the storage of lithium in the TiO2 sheath,” the researchers wrote in a study published in Chemistry of Materials. “On the other hand, the CNT itself can also store lithium whereby this storage kinetics is, in turn, improved by the presence of the nanoporous TiO2 … [which] enables rapid access of lithium-ions from the liquid electrolyte.” These symbiotic advantages could directly lead to improvements in lithium-ion batteries that use nanocable-based anodes. The researchers found the new anodes offer improvements in storage capacity, release rate, and cycling performance compared with either pure CNT or pure TiO2. The nanocables also had good reliability, showing almost no capacity loss after one hundred cycles. More information: Fei-Fei Cao, et al. “Symbiotic Coaxial Nanocables: Facile Synthesis and an Efficient and Elegant Morphological Solution to the Lithium Storage Problem.” Chemistry of Materials. doi:10.1021/cm9036742via: Chemistry World Scientists have developed coaxial nanocables: carbon nanotubes coated with titanium dioxide. Image credit: Cao, et al. (c)Chemistry of Materials. Titanium-coated nanotube cables shown under a transmission electron microscope. Image credit: Cao, et al. (c)Chemistry of Materials. These abilities are also competitive with graphite-based anodes, which are commonly used in today’s lithium-ion batteries. Plus, the nanocables are easy to produce and made of inexpensive materials, which could make them attractive for commercial use. “This fascinating symbiotic behavior and the fact that the cable morphology leads to an efficient use of this symbiosis makes this solution match the requirements of lithium-ion batteries extremely well,” the researchers wrote.The scientists hope that this demonstration of the synergistic benefits of hybrid materials might motivate further research in using hybrid materials for other energy storage devices, such as supercapacitors. Explore further (PhysOrg.com) — By itself, titanium dioxide (TiO2) is a very poor electrode. Electrons move very slowly through the material – so slowly, in fact, that it can take years to fill a millimeter-thick piece of TiO2. However, things change when the TiO2 is extremely thin: a 10-nm-thick piece of TiO2 can be filled with electrons in milliseconds. Inspired by this ability, scientists have recently investigated whether TiO2 could be useful for fabricating high-capacity batteries. New electrodes may provide safer, more powerful lithium-ion (Li-ion) batteries Citation: Nanocables could lead to more powerful lithium-ion batteries (2010, January 28) retrieved 18 August 2019 from https://phys.org/news/2010-01-nanocables-powerful-lithium-ion-batteries.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.
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. More information: “Emergence of modern continental crust about 3 billion years ago” Nature Geoscience, 2015. DOI: 10.1038/ngeo2466AbstractThe continental crust is the principal record of conditions on the Earth during the past 4.4 billion years. However, how the continental crust formed and evolved through time remains highly controversial. In particular, the composition and thickness of juvenile continental crust are unknown. Here we show that Rb/Sr ratios can be used as a proxy for both the silica content and the thickness of the continental crust. We calculate Rb/Sr ratios of the juvenile crust for over 13,000 samples, with Nd model ages ranging from the Hadean to Phanerozoic. The ratios were calculated based on the evolution of Sr isotopes in the period between the TDM Nd model age and the crystallization of the samples analysed. We find that the juvenile crust had a low silica content and was largely mafic in composition during the first 1.5 billion years of Earth’s evolution, consistent with magmatism on a pre-plate tectonics planet. About 3 billion years ago, the Rb/Sr ratios of the juvenile continental crust increased, indicating that the newly formed crust became more silica-rich and probably thicker. This transition is in turn linked to the onset of plate tectonics5 and an increase of continental detritus into the oceans. Earth’s crust slowly being destroyed © 2015 Phys.org One of the difficulties with determining the age of the Earth’s crust is that the crust itself is constantly undergoing melting and re-deposition due to subduction. This is a larger factor for the ocean floor than in continental crust because the continental crust is thick and buoyant, making it less susceptible to subduction. By combining information from various radioisotope pairs found in the continental crust, one can unearth clues as to how the crust was formed and when. In this paper, Dhuime, et al. studied the abundance of rubidium compared to strontium. Rubidium (87Rb) becomes strontium-87 (87Sr) through radioactive decay. Strontium-87 has a half-life of 48.8 billion years. Strontium-86, the most abundant isotope of Sr, is stable and does not undergo radioactive decay. Therefore, the abundance of 87Sr in the continental crust can be traced to the radioactive decay of 87Rb, and based on its half-life, one can determine the age of a rock sample.Whenever the Earth’s crust re-melts or is formed from magma deposition, the amount of 87Rb and silica increases in the residual melt, but the amount of 86Sr does not. Consequently, 87Rb/86Sr correlates with silica content. The silica content is important because the composition of the continental crust is predominantly silica, while the early Earth’s crust was likely mafic, or composed of predominantly iron and magnesium. To calculate 87Rb/86Sr, Dhuime, et al. first determined the 87Sr-to-86Sr ratio and then determined what the ratio was at the time when the crustal melt crystallized. From this they were able to calculate 87Rb/86Sr and therefore determine the amount of silica present at various time periods.This calculation was performed for over 13,000 volcanic and plutonic rock samples of varying ages, based on neodymium model ages. Results show that at about 3 billion years ago the Earth’s continental crust transitioned from a mafic crust to a silica-rich crust. Silica content increased from 3 billion years to 1 billion years ago. At 1 billion years, the amount of silica started to gradually decrease. This result coincides with previous studies using other radioisotope ratios. Furthermore, Dhuime, et al.’s data show that there is a positive correlation between the increase in 87Rb/86Sr and silica and crustal thickness. The authors point out that the gradual increase of 87Rb/86Sr from 3 billion years to 1 billion years may indicate that the Earth’s continental crust was thickening. They estimate that the average thickness of new continental crust increases from ~20 km at 3 billion years ago to ~40 km at 1 billion years ago, and then decreases to ~30 km to the present.Since subduction is a result of plate activity, the transition at 3 billion years may also indicate the onset of plate tectonics. The thickness of new continental crust reached a maximum and then began decreasing. The authors point out that this may coincide with the time of the Rodinia supercontinent and mountain formation.Overall, this study provides compelling evidence that the continental crust formed 3 billion years ago, coinciding with the onset of plate tectonics. Additionally, silica content could be used as a metric for determining crust thickness over time. Journal information: Nature Geoscience
Kolkata: A 41-year-old man committed suicide by hanging himself inside his house at Salt lake EE Block on Thursday morning. Police came to know that the victim Samanway Bhowmick was an LIC agent. The 41-year-old man used to stay alone in the house. Someone known to the victim went to the house and found the man hanging from the ceiling. He informed the matter to other neighbours in the area, who contacted the police. Police went and sent the body for an autopsy. They have initiated a probe in this connection and came to know that the victim had set the volume of his TV ti highest so that no one could hear even if he cries for help. Though police are yet to ascertain the exact reason, investigating officers suspect that financial trouble could be the reason for which he committed suicide.
Darjeeling: The Joint Forum of Trade Unions of West Bengal announced a series of agitation programmes, in demand of the implementation of minimum wages in the tea industry of the state.A meeting of the Joint Forum resolved that on June 27 and 28, memorandums will be given to District Magistrates, Superintendent of Police and GTA chairman, with the demand of implementation of minimum wages in the tea gardens.One June 24, the Joint Forum will hold a public meeting at Mirik, to address various issues including minimum wages, land documents for tea garden workers and the Margaret’s Hope incident of June 25, 1955, which is commemorated as martyr’s day. Also Read – Heavy rain hits traffic, flightsIncidentally on June 25, 1955, ajoint movement had been called by the trade unions of All India GorkhaLeague and undivided CPI at Margaret’s Hope Tea Garden, 24 km from Darjeeling.On that day, workers had assembled in Margaret’s Hope Tea Garden, to submit a 14 point charter of demands.A scuffle had taken place between the management and the workers and in the police firing that ensued, 6 people died and many were injured.The ones who were killed were Amrit Maya Kamini (18), Moulik Sobha Raini (23), Kancha Sunwar (22), Padam Bahadur Kami (25), Jitman Tamang (45) and Kaley Limbu (14). Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killed”On June 25, martyr’s day will be observed by all tea garden workers in Darjeeling, Terai and Dooars, before work in the garden commences,” stated Zia Ul Alam, convenor.On July 2, 3, 4 and 5, gate meetings and demonstrations will be held in front of all the 87 tea gardens in the Hills.”We feel that the government will pay heed to our just demand and implement minimum wages at the earliest. If the above programme fails to yield the desired results, then we will chalk out our future course of action. We appeal for support from one and all for our cause. Our agitation will be peaceful and democratic,” stated Alam.At present, workers are getting a daily wage of Rs 160. In 2015, a tripartite agreement was signed between operating trade unions, management of gardens and the state government, stating that minimum wages would be implemented. Recently, Rs 17.50 was given as interim hike to the daily wages.
Kolkata: The state Education department on Monday clipped the wings of the District Inspectors (DI) of schools when it comes to teacher recruitment and directed them to inform the district magistrate and the Education department about the resolution of the managing committee, before taking any decision on the same.The decision was taken at a meeting with the DIs of schools across the state that was chaired by state Education minister Partha Chatterjee, secretary of School Education Manish Jain and senior officials of the department. All the DIs of the state, except Darjeeling, Siliguri and North Dinajpur, attended the meeting. Also Read – Rain batters Kolkata, cripples normal life”The DIs would send the recommendation of the managing committee to the District Magistrate and to the Commissioner of School Education, before taking any decision regarding recruitment of teachers,” a senior official of the Education department said. According to sources, the minister expressed his displeasure over the decision of shuffling of teachers at Daribhit High School in Islampur and reprimanded some DIs for taking an aggressive role in the recruitment or shuffling of teachers. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killed”The reshuffling of posts in Daribhit School is illegal. The DIs should consult the district magistrate and the School Education department before such reshuffling to avoid any untoward incident,” the official said. According to sources, Daribhit High School had no vacancy. Among its 22 sanctioned posts, five are para-teachers. “It is nothing wrong on the part of any school seeking extra teachers. But suddenly some people turned vocal, alleging that teaching posts are vacant and were seen with flags of a certain party, causing violence in which two students were killed. Chief Minister Mamata Banerjee has directed to deal with the situation strongly,” Chatterjee said.
Planning a baby? Then stop drinking soda or sugar-sweetened beverages, as intake of one or more such drinks a day – by either partner – may decrease the chances of conceiving, warns a study. The findings showed both female and male intake of sugar-sweetened beverages was associated with 20 per cent reduced fecundability – the average monthly probability of conception. Females who consumed at least one soda per day had 25 per cent lower fecundability, while male consumption was associated with 33 per cent lower fecundability. Also Read – Add new books to your shelf”We found positive associations between intake of sugar-sweetened beverages and lower fertility, which were consistent after controlling for many other factors, including obesity, caffeine intake, alcohol, smoking, and overall diet quality,” said lead author Elizabeth Hatch, Professor at the Boston University School of Public Health (BUSPH).”Couples planning a pregnancy might consider limiting their consumption of these beverages, especially because they are also related to other adverse health effects,” Hatch said, in a paper published in the journal Epidemiology. Also Read – Over 2 hours screen time daily will make your kids impulsiveIntake of energy drinks was related to even larger reductions in fertility, although the results were based on small numbers of consumers. Little association was found between intake of fruit juice or diet soda and fertility.Previous studies have linked the consumption of these beverages to weight gain, Type 2 diabetes, early menstruation and poor semen quality. For the new study, the team surveyed 3,828 women aged 21 to 45 living in the US or Canada and 1,045 of their male partners.
Kolkata: Bengal Governor Keshari Nath Tripathi inaugurated the ‘Gandhi Gallery – Mahatma Gandhi Interpretation Centre’ at Netaji Subhash Chandra Bose International Airport on Thursday.The gallery has been thrown open to the passengers travelling through Kolkata Airport and it is located inside the domestic arrival hall of the terminal building. As part of the 150th birth anniversary of Mahatma Gandhi, Airports Authority of India, in association with Also Read – Rs 13,000 crore investment to provide 2 lakh jobs: MamataGandhi Smriti and Darshan Samiti, has embarked on establishing ‘Gandhi Gallery – Mahatma Gandhi Interpretation Centre’ at different Airports across the country, to propagate Gandhiji’s ideals and principles. People will be able to see Gandhiji’s association with local leaders and freedom fighters through 24 display panels. His association with Rabindranath Tagore and Netaji Subhas Chandra Bose has also been prominently displayed at the gallery. Also Read – Lightning kills 8, injures 16 in stateSodepur Ashram where Gandhiji spent some time, his tour to Noakhali, and his efforts to maintain communal harmony in 1946-47 have also been put on display at the gallery. In addition, a digital kiosk has also been installed to make the passengers aware about the life and times of the father of the nation. It also includes a quiz and films on Gandhiji and other information, which would interest the young generation. Kaushik Bhattacharjee, Airport Director, Sankar Kumar Sanyal, Member, Executive Committee, Gandhi Smriti and Darshan Samiti and Dipankar Shri Gyan, director, Gandhi Smriti and Darshan Samiti, were also present during the programme among other dignitaries.