August, 2019 Archive

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New PV cell generates electricity from IR and UV light

first_img 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. (PhysOrg.com) — A prototype of a new type of photovoltaic (PV) cell that generates electricity from visible, infrared and ultraviolet light has been demonstrated by a group of Japanese scientists. It could lead to the development of a highly-efficient PV cell in the future, without needing multijunction cells. IMEC unveils promising mechanically-stacked GaAs/Ge multijunction solar cell The research was led by Associate Professor Saki Sonoda of the Kyoto Institute of Technology. The prototype cell has a high open voltage (Voc) at around two volts, but a low energy conversion efficiency. Sonada and the team hope the conversion rates can be improved. Photovoltaic materials convert light to electricity at the atomic level by absorbing photons of light and releasing electrons that can be captured to produce an electric current. Most PV cells are multijunction devices, with single junction cells stacked in descending order of band gap. The cell at the top captures high-energy photons, while those at the bottom with lower band gaps capture the lower energy photons. The new cell is able to capture photons with a wide range of energies in a single junction cell.The team made the 10 mm square PV cell by adding elements such as manganese (Mn) or cobalt (Co) to the transparent semiconductor material gallium nitride (GaN). When the element is added, the absorption coefficient of GaN is higher, allowing a much wider spectrum of light to be absorbed, including infrared, visible and ultraviolet. A cell made from p-type GaN with added Mn or Co is transparent and black, whereas GaN without additions is not.Manganese and cobalt are 3d transition metals, which are elements in which the number of electrons in the 3d orbit (inside the outermost orbit) increases as the number of protons in the nucleus (and hence the atomic number) increases. Other well-known 3d transition metals include titanium (Ti), iron (Fe), copper (Cu) nickel (Ni) and zinc (Zn). The scientists tried several 3d transition metals with GaN and obtained good results with many of them, including manganese and cobalt. Other researchers have tried adding indium (In) to gallium nitride PV cells with the aim of narrowing the band gap to enable it to absorb a wider wavelength band of visible light.The prototype was demonstrated during a 90-minute lecture at the 57th Spring Meeting of the Japan Society of Applied Physics on March 19.center_img Citation: New PV cell generates electricity from IR and UV light (2010, March 24) retrieved 18 August 2019 from https://phys.org/news/2010-03-pv-cell-electricity-ir-uv.html © 2010 PhysOrg.com The PV cell prototyped at the Kyoto Institute of Technology by adding cobalt to a p-type GaN thin film and laminating an n-type material (right). The cell with an absorbing layer measures 10 x 10mm. The surrounding thin rectangular patterns are electrodes. And the p-type GaN thin film without cobalt (left). Image via: Tech on.last_img read more

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Scientists address manyelectron problem by modeling an infinite chain of hydrogen atoms

first_img(Phys.org)—For the first time, scientists have determined the equation of state of an infinite chain of hydrogen atoms, which tells the amount of energy each hydrogen atom has, given the bond length between adjacent atoms. Steady-state density functional theory 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: Mario Motta et al. “Towards the Solution of the Many-Electron Problem in Real Materials: Equation of State of the Hydrogen Chain with State-of-the-Art Many-Body Methods.” Physical Review X. DOI: 10.1103/PhysRevX.7.031059 Explore further Journal information: Physical Review X © 2017 Phys.org But what is even more interesting for the scientists than the result itself is how they achieved it: by using 20 or so state-of-the-art computational methods that have recently been developed to analyze many-electron systems. The new results offer a first glimpse of what these methods may offer for understanding and predicting the properties of many complex materials, and ultimately designing completely new materials.The chemists and physicists behind the new study are members of the Simons Collaboration on the Many-Electron Problem, whose ultimate goal is to find methods to model and understand many-electron systems. These are basically any systems that—like an infinite chain of hydrogen atoms— contain large numbers of atoms or molecules, and, therefore, many electrons.Electron-electron interactions play a large role in determining a material’s properties, such as how well it conducts electricity and how hard or soft it is. This information is critical for future initiatives in which researchers design new materials with specific desired properties. Although it’s relatively easy to model systems with a few electrons, as the number of electrons grows, the number of possible states that a system can occupy grows exponentially. Modeling such systems then becomes increasingly difficult, since the electron interaction effects are so strong that even the best independent-electron theories break down.In order to model many-electron systems, researchers have developed several many-electron computational methods that rely on advanced concepts in mathematics and computer science, such as cluster embedding theory, Monte Carlo methods, and tensor networks. But so far, no method exists that can treat all many-electron systems systematically with high accuracy and low computational cost. Citation: Scientists address many-electron problem by modeling an infinite chain of hydrogen atoms (2017, October 9) retrieved 18 August 2019 from https://phys.org/news/2017-10-scientists-many-electron-problem-infinite-chain.html Potential energy curve of H10 (top) and deviations from FCI (bottom), in the minimal STO-6G basis. Credit: Mario Motta et al. Physical Review X. DOI: 10.1103/PhysRevX.7.031059 In the new study, the scientists used a linear chain of hydrogen atoms as the first benchmark system to test many of these new theoretical methods. By applying approximately 20 of the newest methods to the same problem, the scientists were able to validate and cross-check the results of each method. Although the entire process was computationally complex, it allowed the scientists to combine the strengths of complementary methods and determine the energy per atom to a high degree of accuracy. They could then compare the accuracy of individual methods, which revealed that many of the new methods achieved a high degree of accuracy by themselves. “There are several facets to this work,” Shiwei Zhang, a physics professor at the College of William and Mary and the paper’s corresponding author, told Phys.org. “It produced extensive data and comparisons, as a benchmark study was designed to do. It also spurred many algorithmic developments in the different methods, which resulted from the interactions and ‘friendly competition.’ Perhaps less obvious but most important: it brought people and algorithms together, helped focus the field, and pushed the community to work synergistically in the most productive ways.”The scientists are making the vast amount of data produced in this study available to other researchers, which will soon be available here. They expect that the data will be useful for analyzing the computational methods, benchmarking new methods, studying other many-electron systems, and gaining a deeper understanding of many areas throughout condensed matter physics, quantum chemistry, and materials science, among other fields.”One short-term goal is to determine the properties of the hydrogen chain,” Zhang said. “Surprisingly, even in this relatively simple ‘material,’ there are important questions for which we do not have definitive answers. We have computed the equation of state. But, for example, what are the electrical and magnetic properties? “More generally, we would like to expand such benchmark studies to more complex materials. We will continue to develop our computational methods and software. And of course we would like to apply them to tackle the most challenging many-electron problems in molecules and solids important to science and technology.”last_img read more

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Its she who stands tall

first_img16 December, 2012 was the day which no one can easily forget. The entire nation shook as the day witnessed the one of the worst atrocities when a young girl was gang-raped and bruatally killed. Paying a tribute to the martyr of the tragic incident, Dhoomimal Art Gallery presents the art exhibition Nirbhaya, titled after the name given to the braveheart. The show is curated by K R Subbanna and will be inaugurated by Padma Bhushan awardees Raja Reddy, Radha reddy and Kaushalya Reddy. Artworks of over 50 artists will be displayed at the exhibition. The participating artists are – Arpana Caur, Gopi Gajwani, Gogi Saroj Pal, Ved Nayar, Sanjay Bhattacharyya, Nupur Kundu, and many others.  Also Read – ‘Playing Jojo was emotionally exhausting’This event is conceptualized to pay homage to the people who lost their lives and also to express solidarity against atrocities with the support of the artist fraternity who are enthusiastic to express their feelings together with Dhoomimal Gallery, Gandhi National Center for Arts, Creative Mind Publications and NIV Art centre.The event is divided into three parts. The first part of the exhibition displayed the works by the eminent artists of the Country at Matigarh, IGNCA, which concluded on 20 April.  Also Read – Leslie doing new comedy special with NetflixThe second part was the extension of the show of young artists at the NIV Art Center that started on 26 April and concluded on 10 May. It was the outcome of the one day art camp which was held at Matigarh, IGNCA on 6 April as part of the exhibition Nirbhaya- Multiple expressions. Finally, this event is being documented in the form of an illustrated catalogue that will give each of the participating artists their own individual space. Where: Dhoomimal Gallery, G-42,Connaught Place. When: On till 25 May  Timings:  11 AM – 7 PMlast_img read more

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Tuck into delectable delights this New Year

first_imgThe year passes by into the realms of fond memories giving way to surprises and new promises for a bright year ahead. Travel through the epicurean legends of Italy, India and South-East Asia at each of our restaurants for a gala New Year’s Eve dinner on December 31 at The Imperial. 1911 offers a sumptuous New Year Eve dinner buffet with a selection of fine delicacies like Seared yellow fin tuna nicoise with quail eggs, Tenderloin picattas amongst other succulent delights at Rs 5000 inclusive of taxes per person. Also Read – ‘Playing Jojo was emotionally exhausting’San Gimignano presents delectable Tuscan Italian fare to choose from featuring Risotto Alla Parmigiana E Pesto Di Ovlie Nera, which is parmesan cheese risotto cooked with sun dried tomatoes and topped with black olive pesto, Manzo Alla Griglia E Gorgonzola Dolce-grilled sliced tenderloin with sautéed butter spinach, sweet gorgonzola sauce and fried artichoke amongst others at Rs 6500 inclusive of taxes per person.Daniell’s Tavern – Pan Indian fine dining, offers an exclusive celebration with the taste of ancient India with Gucchi Paya, Pathar Boti Kebab, Murgh Musallam Nawabi and Khubani ka Meetha at Rs 6000 inclusive of taxes per person.Extend the new year celebrations and elevate your festive spirits with us as we lay out the most spectacular new year brunch buffet on January  1, 2016 at 1911 at Rs 4000 all inclusive per person, where you can enjoy your favourite world cuisine and welcome the New Year in style. The festive brunch would be open from 12:30 pm to 3:30 pm.last_img read more

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Overuse of electronic gadgets triggers early ageing Doctors

first_imgAccording to experts, “tech neck”, which leads to sagging skin, dropping jowls, and creases above the clavicle, seriously affects facial looks of the person by causing frown lines, undereye bags, and horizontal lines on the neck along with fat prominences.“People who bend down constantly for long hours while using any handheld electronic device, like smartphones, tablet or computers, are more likely to get wrinkles. The bending position while texting on mobile phones can cause neck, back and shoulder pain, apart from headache, numbness, tingling in the upper limb and pain in hands, arm, elbows and wrists,” said Vinod Vij, Cosmetic Surgeon, at Mumbai-based Fortis Hospital. Also Read – ‘Playing Jojo was emotionally exhausting’A recent report by the Internet and Mobile Association of India (IAMAI) had revealed that the number of mobile internet users in the country was expected to reach 371 million by June 2016. As much as 40 per cent of the users consist of youngsters between the age group of 19-30. Experts have said that the frequent forward flexion causes changes in the cervical spine, curve, supporting ligaments, tendons and musculature, as well as the bony segments, commonly causing postural change. Also Read – Leslie doing new comedy special with NetflixMohan Thomas, Senior Cosmetic Surgeon, Cosmetic Surgery Institute, said, “As people do not realise the negativity they are causing to their neck bone and the skin, tech obsessed people should take necessary steps to avoid the overuse of the electronic gadgets.” He said the overuse of smart phones causes shortening of the neck muscles. “Apart from shortening of the neck muscle it also increases the gravitational pull on the skin. Ultimately, this results in sagging skin, double chin, marionette lines (vertical lines from lips to chin) and loose jowls (drooping jawline). All these signs have been collectively labelled medically as “smartphone face,” he said.last_img read more

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Spencers now offers bread made from 2000yrold Roman recipe

first_imgKolkata: If you want to tickle your taste buds with almost 2,000 years old Roman bread? Then, here is the good news for Kolkatans as Spencer’s has prepared the historic bread with the same ingredients, the Roman bakeries might have followed in 79 AD.Internationally reputed bread maker Spencer’s in Kolkata, after a series of experiments, has successfully recreated Roman bread which was very popular in Pompeii. The city of Pompeii was destroyed during the eruption of Mount Vesuvius around 2,000 years ago. To celebrate 400 days of the inception of its Park Street store, the Spencer’s from Monday afternoon has started offering this historic Pompeiian bread to consumers. The bread will be available in a 400 gram pack at a cost of Rs 60 from 30 Spencer’s stores as well in the city from 30 October. Also Read – Rain batters Kolkata, cripples normal lifeA Spencer’s spokesperson said on Monday that in the Western world, there had been inquisitiveness about the carbonized loaves excavated from Pompeii many years ago. According to the chief chef, western bread makers like many of us wonder how the original Pompeiian breads might have been looked like, how they might have tasted or what ingredients might have been used by the then bakeries to prepare those loaves. The funny looking bread was called “Panis Quadratus” which was excavated in a fossilised state many years later. It is presumed that the city of Pompeii had been destroyed due to a volcanic eruption. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killedAccording to a senior official of the Spencer’s, the Pompeii bread is prepared with ingredients like — whole wheat flour (Atta), wheat refined flour (Maida), wheat bran, extra-high dietary fibre, yeast, starter, salt and others. Researchers tell us that the professional bakers in Rome and Pompeii did not exist until 2 nd Century BC. According to historical sources, the ancient Roman breads were made of flour, whole-wheat flour, tepid water, salt and other spices. The preparation time of the bread during the Roman era might have remained up to 30 minutes.last_img read more

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Why morning people should not work at night

first_imgIf you are a morning person, working in night shifts may affect you more, a study said.According to the study, morning persons demonstrate a quicker reaction time when solving unusual attention related tasks when working at night, but they are more prone to make errors.This may be the result of sleep deprivation and a relative increase in the time spent awake which negatively impacts the brain’s attention system, the researchers said.The study showed that morning persons completed their tasks quicker than the night persons, but with errors. Also Read – Add new books to your shelfOn the contrary, night persons were found to spend more time finishing their tasks. But, their level of accuracy in completing the task was higher, the researcher noted.“To deal with the most difficult test – resolving a conflict of attention – it was necessary not only to concentrate on the main visual stimulus, but at the same time to ignore accompanying stimulus that distract from the core task,” said Andriy Myachykov from Oxford University.Though night people turned out to be slower, they were more efficient compared to the early risers. Also Read – Over 2 hours screen time daily will make your kids impulsive“Our study demonstrated how night owls working late at night ‘sacrifice’ speed for accuracy,” Myachykov added.The results of this study may be useful for people who work night shift and could challenge the education system and human resources management in certain areas.For pilots, air traffic controllers, drivers, etc, attention, the ability to deal with large sets of data, and reaction time are all very important. During emergencies, these features could play a vital role.The study is available in the journal Experimental Brain Research.last_img read more

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Idol preservation Metal wood gain priority over clay

first_imgHave you wondered where the beautiful idols of the Goddess Durga vanish once the pujas are over and the pandals dismantled? While some of these idols – a handful – are preserved by the state Government at various museums or parks or private collectors, the normal clay idols are simply immersed in the Ganges or other water bodies after Dussehra.Which idols of the Goddess are being preserved? Bhabotosh Sutar, the artist behind the Chetla Agrani Club puja – mentored by Bengal’s minister for Urban Development Firhad Hakim – has had about six of his Durga idols preserved so far. The beautiful idol he has carved out of a single, antique block of mahogany this time will also be preserved at the state government-run Eco Tourism Park in Rajarhat. This is going to be the third of his idols to be preserved at the park.”Other idols have been collected by ASI, Derek O Brien and ITC Shonar Bangla. These are all made from wood, metal and even terracotta. I’m hoping that my mahogany Durga(for Chetla Agrani) will be preserved well as a piece of public art”, Sutar told Millennium Post. Also Read – Add new books to your shelfThe trend started in 2011 when the Mamata Banerjee government came into power in Bengal. “A warehouse was built near the Golpark lakes where some idols were collected and preserved. But the state Government also does not have the infrastructure to preserve all Durga idols” Sutar said. Rupchand Kundu, whose idol at the Behala Friends Club is likely to be preserved this time at the state Government run Eco Park Club, said, “It has to be kept in mind while making the idol that this is not just a temporary construct but an artwork that needs to be preserved for the generations to come. In this idol, made from fly ash, I have shown that even ordinary waste can transform into something divine when light is thrown on it”, Kundu told Millennium Post. Also Read – Over 2 hours screen time daily will make your kids impulsiveIt all depends on the material used for making the idol. “Clay is difficult to preserve in the open air. However Durga idols which are made from wood or metals or fibre glass can be preserved in a museum or inside of a building as objets de art”, said eminent artist Subrata Gangopadhyay, an advisor to the Sreebhumi Sporting Club puja built around the Bahubali theme. Gangopadhyay has painted extensively on the Sindurkhela theme earlier which is associated with Durga pujas. Another artist whose idols have been preserved is Sanatan Dinda, though he mostly works with clay.last_img read more

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We have to be influential enough to create jobs

first_imgSabyasachi Mukherjee just wanted to earn money to get on an airplane and travel the world when he entered the fashion industry, and went on to make a special place for himself by weaving traditional stories with threads of Indian culture through his creations. India’s ace couturier says he wants to make sure that he “comes up with something that the copy market can copy” that in turn creates jobs in the market. In an interview , the designer looked back to the time when he entered the industry and how a sense of responsibility towards the country and people who work for him has seeped in. Also Read – Add new books to your shelf”When I first started out, I wanted to make enough money so that I could get on an airplane and travel to any part of the world that I wanted to. That was a selfish motivation because I was young and I could not think of anybody but myself; today I have 1,900 people working under me, I have to pay salaries every month, their children are going to school, it’s a big responsibility,” Sabyasachi told.He continued: “And I also look at the social responsibility of what we are doing in the country. We are one of the largest brands in the country; so I have to make sure that every year I come up with something that the copy market can copy, because every time that the copy market copies something, you’re creating jobs – and for me the responsibility of Also Read – Over 2 hours screen time daily will make your kids impulsivebeing able to do something that drives an economy, whether the economy panders to us or whether it panders to somebody else’s wallet, it doesn’t matter, but we have to be influential enough to be able to create jobs in this country.”For me that’s very important.”So is that his biggest challenge as a designer?”My biggest challenge is to make sure that I’m proud of the work that I do and I also create enough business for art and craft to survive.”After graduating from the National Institute of Fashion Technology, Sabyasachi started an eponymous label in 1999 and went on to make waves in the international fashion scene by using Indian textiles with a contemporary twist. He is one of the few names in Indian fashion to participate at fashion weeks in Milan, New York and London. The designer, whose creations have been flaunted by the likes of actresses Shabana Azmi, Renee Zellweger, Reese Witherspoon, Aishwarya Rai Bachchan, Tabu, Sushmita Sen and Kareena Kapoor Khan, hails from Kolkata. He has lent his creativity in fashion to films such as Black, Guzaarish and Paa.Sabyasachi works closely with artisans to tell stories with his sartorial creations.”What’s good about the artisans right now is they are not being treated as artisans any more; they are treated as artists and there is a lot of respect, there is a lot of social and cultural respect that’s coming.”They are buying homes, their children are going to school, they have technology aiding them, they have business managers and accountants, they have CAs looking into their books. I think what they are doing is they are shaping themselves from fragile, small companies into strong robust businesses.”Sabyasachi has put in his creativity to use by creating ensembles for women, men and children. He says the chance to design wall coverings came at the right time.”I wanted to do something in interiors, but I also wanted to do it with one of the largest companies in the country .”What is he working on at the moment?”On a speech that I’m going to give at Harvard (University). I don’t know what I’m going to say; so that’s my big fear as I’m going to represent my country.”last_img read more

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Calcutta University forms panel to counter plagiarism

first_imgKolkata: The Calcutta University (CU) has constituted a committee that will frame guidelines to check plagiarism.The committee has been formed according to the guidelines of the University Grants Commission (UGC) in this regard. The faculty council of the varsity has already approved the decision of setting up this committee. “There is a guideline on plagiarism framed by the University Grants Commission. But there should be a specific policy of all universities on the basis of these guidelines to curb the practice. The CU did not have any such guidelines. The researchers used to send their papers to the library following which the latter checked on certain aspects and prepare a report on the originality of the research paper. But we have been discussing for quite some time that there should be a specific guideline in this regard,” a senior member of CU teacher’s association said. The committee has deans of seven faculties and the librarian of the varsity. Also Read – Rs 13,000 crore investment to provide 2 lakh jobs: MamataThe faculty council also decided to form another committee for redrafting of regulations of PhD. The varsity has been facing some problems regarding Phd regulations for quite sometime. “We hope to come out with a regulation that will be beneficial for the researchers and will be able to dispel any doubts in their minds,” a senior official of the varsity said. The faculty council of the university has been set up only in the last week of March. It is headed by the Vice-Chancellor Sonali Chakravarti Banerjee and pro Vice-Chancellor Dipak Kar. The faculty council has been a long-standing demand of university teachers as it will be providing a platform for them to voice their opinion on academics or similar matters. The Jadavpur University has a faculty council for a long time in which important decisions about academics are taken.last_img read more

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