Home » 2019 » August

Nanocomposite material provides photonic switching

center_img “There are many applications for this work,” Qihuang Gong tells PhysOrg.com. Gong, along with his colleagues Xiaoyong Hu, Ping Jiang, Cheng Xin, Hong Yang, demonstrated a nano-Ag:polymer composite material can be used for photonic switching. Their work appears in Applied Physics Letters: “Nano-Ag:polymeric composite material for ultrafast photonic crystal all-optical switching.”“The nonacomposite material is composed of Ag nanoparticles dispersed in a MEH-PPV matrix,” Gong explains. “MEH-PPV is a nonlinear organic conjugated polymer material.” He points out that the nano-Ag:MEH-PPV composite has a large nonlinear susceptibility and very fast response time under resonant excitation, making it ideal for ultrafast optical switching applications. “Ultrafast response is maintained by use of a fast energy transfer process.” The Chinese group found that it is possible to achieve a nonlinear response time of 35 ps.Join PhysOrg.com on FacebookIn order to experiment with the nanocomposite material, the Peking University group employed a method of femtosecond pump and probe. The Ag nanoparticles, and the MEH-PPV molecules, were resonantly excited by a pump laser. During this process, energy is transferred from the MEH-PPV molecules to the Ag nanoparticles. A delay line was used to change the temporal relations between the pump and probe pulses. “Under the excitation of the pump laser,” Gong explains, “the effective refractive index of the nano-Ag:MEH-PPV composite material changes, which leads to the changes of the photonic band gap and the transmittances of the probe laser.” When this happens, the switching effect is realized.Gong points out that this particular composite material is ideal for all-optical switching at fast speeds. “MEH-PPV possesses high environmental and thermal stability, high optical damage threshold, and good film quality,” he says. Additionally, this material is easy to manufacture, and can be produced using current technology. Gong also notes that this nano-Ag:MEH-PPV composite material has very good waveguide properties. “This approach can be used in practical applications now.”There are limits to this nanocomposite material, Gong concedes. One of the main issues is that, “the organic polymer matrix can be damaged by a strong mechanical force.” This means that the delicate material would need a certain level of careful handling in some cases. Gong also admits that the working wavelength is only about 800 nanometers. More study is needed, Gong says. “Our next steps are to study new approaches to achieving a large nonlinear susceptibility and a femtosecond nonlinear response time simultaneously.”By understanding how these composite materials work, it should be possible to create new materials that can provide a basis for smaller, more efficient devices.More information: Xiaoyong Hu, et. al. “Nano-Ag:polymeric composite material for ultrafast photonic crystal all-optical switching.” Applied Physics Letters (2009). Available online: link.aip.org/link/?APPLAB/94/031103/1 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. Citation: Nanocomposite material provides photonic switching (2009, February 9) retrieved 18 August 2019 from https://phys.org/news/2009-02-nanocomposite-material-photonic.htmllast_img read more

Continue reading »

Fungus uses zombie female beetles to infect males

first_img Citation: Fungus uses zombie female beetles to infect males (2017, June 12) retrieved 18 August 2019 from https://phys.org/news/2017-06-fungus-zombie-female-beetles-infect.html Goldenrod solider beetles are native to North America—they live in meadows and fields and survive by eating flowers. They mate while sitting atop a flower, which is a behavior that may contribute to their demise, the researchers find. The fungus Eryniopsis lampyridarum also lives on the same types of flowers and infects beetles when they visit. Once infected, the beetle’s jaws clamp hard onto the flower, freezing the beetle in place as it dies. Nearly a day later, its wings open as if preparing to take flight. For infected male beetles, the story ends there, but for the females, there is more to come. As they lay there atop the flower, the dead creatures appear to males as ripe for procreation—they fly over and attempt to mate with the zombie female, and in the process become infected with the fungus.Intrigued by the way the fungus has evolved to better spread its spores, the researchers collected beetle specimens and brought them into their lab for study. They report that out of a total of 446 beetles (281 females, 165 males) studied, 90 were infected with the fungus. They also found that it took between 15 to 22 hours for the wings to expand, and that soon thereafter, the fungus also caused the victim’s abdomen to swell. They suggest the fungus causes the response in its dead victims as a means of attracting potential hosts—the outspread wings and oversized abdomen cause the female to look bigger, which is something the males apparently find attractive.The researchers plan to continue their study of the beetles and the fungus, suggesting that it might be interesting to see if they gluing the wings shut impacts on infectivity. 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. Scientist uses fungus to destroy bark beetles © 2017 Phys.org Explore further Credit: CC0 Public Domain More information: Donald C. Steinkraus et al. Zombie soldier beetles: Epizootics in the goldenrod soldier beetle,Chauliognathus pensylvanicus(Coleoptera: Cantharidae) caused byEryniopsis lampyridarum(Entomophthoromycotina: Entomophthoraceae), Journal of Invertebrate Pathology (2017). DOI: 10.1016/j.jip.2017.05.002 A combined team of researchers from the University of Arkansas and Cornell University has found that a type of fungus kills female goldenrod soldier beetles in a unique way—by causing them to attract males, which assists in spreading spores. In their paper published in the Journal of Invertebrate Pathology, the group describes observations they made of the beetle, experiments they conducted in their lab, and the peculiar way the fungus spread itself to new hosts.last_img read more

Continue reading »

For a better tomorrow

first_imgTo promote and find measures for the same a unique and first ever conference to deal with threats linked to survival of entire humanity is being organised in the Capital.The theme of conference is Balancing Panch-Tatwa Strategically towards Sustainability. Panch Tatwa (five elements) are the basic elements of everything in this universe, including our own body. Based on the same the conference is a fusion of modern science and traditional wisdom to restore balance in Panch-Tatwa. Also Read – ‘Playing Jojo was emotionally exhausting’The consequences of man’s action are evident in terms of various phenomenon including global warming, climate change and environmental degradation in general. Various organisations and people are already doing commendable work towards restoring the delicate balance in nature.The conference aims to unify diverse efforts being put forward by various individuals and organisations towards humanity, sustainability, Panch-Tatwa and traditional wisdom. It’s designed to serve as a common platform for various intellectuals and experts from around the world, to exchange ideas culminating into ‘collective wisdom’ and action plan. Also Read – Leslie doing new comedy special with NetflixThe conference is being organised by non-governmental organisation, Aqua Foundation. The collective wisdom from the conference will be compiled as a book and will be disseminated all around the world.The conference committee is chaired by Prof M S Swaminathan renowned for his leading role in India’s Green Revolution, co-chaired by Dr. R K Pachauri serving as the chairperson of the Intergovernmental Panel on Climate Change since 2002, which was awarded the Nobel Peace Prize in 2007.  The proceedings of this conference and its recommendations will therefore have a far reaching consequence in making it a better world, living in harmony with nature.When: 11-13 DecemberWhere: Indian Habitat Centrelast_img read more

Continue reading »

Mexico mass graves Some bodies found not that of students

first_imgThe governor of the southern Mexico state where 43 college students disappeared after a confrontation with police said that some of the bodies recovered from clandestine graves last weekend did not match the missing young people. The federal attorney general, however, said he felt it was too soon in testing of the remains to come to any conclusions. In indicating that some progress had been made in identifying the dead, Guerrero state governor Angel Aguirre gave no details nor did he say if all of the 28 bodies removed by forensic experts had been identified. The remains were uncovered severely burned, and experts are conducting DNA tests in an effort to identify the dead.  Also Read – Pro-Govt supporters rally as Hong Kong’s divisions deepenThe governor spoke at a news conference in Iguala, the city where municipal police have been accused of working with a drug gang in the disappearance of the students on 26 Sept. Attorney general Jesus Murillo Karam declined to confirm or dispute the governor’s comments. ‘I do not know on what the governor based that,’’ he said later in the Guerrero state capital, Chilpancingo. He added that experts still ‘have not finished testing.’’ Aguirre also gave no information on what authorities had found in other mass graves that were discovered.last_img read more

Continue reading »

Arsenicaffected villages get access to worlds cheapest potable water in West Bengal

first_imgMadhusudan Kanti (North 24 Parganas): Areas near Indo-Bangladesh border in West Bengal have witnessed a steep decline in arsenic-related diseases over a period of three years after setting up of a cheap and sustainable surface water purification plant. “In course of periodic medical checkup of a group of patients suffering from arsenic-related diseases, it was revealed that this water purification system has become a boon for them (villagers),” sociologist and founder of Sulabh International Bindeshwar Pathak, the brain behind the water project, said. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killed Many of the villagers living here were forced to migrate to nearby places before they tried, in vain, every attempt to rid the water of the poison. The cost was too high. They had to pay for every drop of purified water they would fetch from distant towns or cities. Diseases related to the consumption of carcinogenic arsenic contaminated water had even claimed lives in the region. But life started changing three years ago when Sulabh International Social Service Organisation (SISSO), in collaboration with a French company, 1001 Fontaines, installed a Rs 20-lakh pond-based water treatment plant in Madhusudan Kanti Village of North 24 Parganas district, some 100 km from Kolkata. Also Read – Naihati: 10 councillors return to TMC from BJP The cost of establishing the plant in Bangaon subdivision, that can produce 8,000 litres of potable water per day at a cost of 10-20 paise a litre, was shared between the French organisation, Sulabh and the villagers. “The villagers and local NGOs maintain this. It is a self-sustainable project with active participation from the villagers and generate employment,” Pathak said. “This is the first time in the world that we have succeeded in producing pure drinking water at a very nominal cost by this new technology and villagers may get direct benefits,” he added. “It is being sold at 50 paise after including other costs like distribution, storing, etc. Even people in neighbouring villages can also safely use this water,” the Sulabh founder further said. Sulabh and the French organisation have also established pilot projects in North 24 Parganas, Murshidabad and Nadia districts of the state, where at many places people are forced to drink arsenic-contaminated water. Pathak believes the entire problem of arsenic-contaminated water could be solved if the West Bengal government took interest and replicated the model. According to the World Health Organisation (WHO), arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment — in air, water and land. It is highly toxic in its inorganic form. Long-term exposure to inorganic arsenic, mainly by drinking contaminated water, eating food grown or even prepared with this water, can cause skin lesions and cancer. WHO says inorganic arsenic is naturally present at high levels in the groundwater of a number of countries, including Argentina, Bangladesh, Chile, China, India, Mexico, and the United States.last_img read more

Continue reading »

There is no other feeling like Theatre Adoor Gopalakrishnan

first_imgIn an attempt to honour theatrical excellence specifically famous theatre personage filmmaker Adoor Gopalakrishnan, the Living Legend Series of 18th Bharat Rang Mahotsav hosted an event to felicitate him. The event was held on Tuesday in the national Capital.Born in the era of British India, Adoor Gopalakrishnan is an eminent director and story writer. An award winning artist in the field of film making, Adoor Gopalakrishnan has given the audience amazing artworks like Swayamvaram and Randaanum. He has also been associated to the roots of theatre in the long run. Also Read – ‘Playing Jojo was emotionally exhausting’“The power of stage is so great that nobody can control it when it attracts you. When it attracted me, I realised that theatre is my area and I devoted my life to it. There is no other feeling like theatre and this is its beauty”, commented Adoor Gopalkrishnan on the beginning of his journey.When the audience asked about his genre of films and the idea behind the theme, he said, “The protagonist of my films is a character who has been left behind by passage of time. It revolves around crisis of misfits.” Also Read – Leslie doing new comedy special with NetflixAs the impact of natural beauty of Kerala has dominated the space in his films, Gopalakrishnan explained, “I prefer to involve all the five major elements of earth in my films.”Focusing on the trend of today’s cinema, Gopalakrishnan mentioned: “The popular cinema of today is the confined cinema. “It is in limit to what the audience wants to see. Audience do not want to think when they watch a cinema.”Play directors Alok Rajwade, Kailash Panigrahi, Rakesh Bedi and Ronlin Foreman, of plays namely Bin Kamche Sanwad, Ghinua, Mera Wo Matlab Nahi Tha and USA’s presentation Pigeon Show: A Play of Fools interacted with the audience in an open session.Mentioning about his ideology of theatre, eminent actor and director Rakesh Bedi said: “I believe in entertainment. To present your views in front of audience, it has to be in an entertaining form. “You cannot go forward and state the facts or views and hope for a positive response.”last_img read more

Continue reading »

Climate change may affect the finest wines

first_imgClimate change is likely to make the wine producing regions of France and Switzerland too hot for traditionally grown grapes, and vineyards in these regions may then have to switch to hotter climate varieties, change long established methods, move or go out of business, suggests a new NASA study.In much of France and Switzerland, the best years for grapes are traditionally those with abundant spring rains followed by an exceptionally hot summer and late season drought. This drives vines to put forth robust, fast maturing fruit, and brings an early harvest. Also Read – ‘Playing Jojo was emotionally exhausting’In the new study, published in the journal Nature Climate Change, the scientists analysed 20th and 21st century weather data, pre-modern reconstructions of temperature, precipitation and soil moisture, and vineyard records going back to 1600. They showed that in the relatively cool wine making areas of France and Switzerland, early harvests have always required both above average air temperatures and late season drought. This is because in the past, droughts helped heighten temperature just enough to pass the early harvest threshold.  Also Read – Leslie doing new comedy special with NetflixThe researchers said that up to the 1980s, the climate was such that without the extra kick of heat added by droughts, vineyards could not get quite hot enough for an early harvest. That has now changed. The study found that since then, overall warming alone has pushed summer temperatures over the threshold without the aid of drought. On the whole, France warmed about 1.5 degrees celsius during the 20th century, and the upward climb has continued. “Now, it’s become so warm thanks to climate change, grape growers don’t need drought to get these very warm temperatures,” said lead author Benjamin Cook, climate scientist at NASA’s Goddard Institute for Space Studies. “After 1980, the drought signal effectively disappears. That means there’s been a fundamental shift in the large-scale climate under which other, local factors operate,” Cook said.“Wine grapes are one of the world’s most valuable horticultural crops and there is increasing evidence that climate change has caused earlier harvest days in this region in recent decades,” Cook pointed out. “Our research suggests that the climate drivers of these early harvests have changed,” Cook noted.last_img read more

Continue reading »

Enjoy festivity with indoor vertical garden

first_imgAs the festive season has begun, people are researching eco-friendly ideas to decorate their house. Having an indoor garden is a unique as well as an environment friendly way to beautify the living space and if you have a space issue then opt for indoor vertical garden. Nowadays, it’s very easy to create your own vertical garden with the presence of new garden concepts like modular planting systems and hanging planters, feel experts. They also shared some useful tips to celebrate the festivals with indoor vertical garden: Also Read – Add new books to your shelf-Frame a vertical garden: It’s a Do It Yourself (DIY) project that can be tried at home without any complication. You need a flat box, a wooden frame, small amount of soil, a metal mesh and a small bud of succulent. Make a photo frame like structure with the flat box and the wooden frame. Add soil into it and cover it with the metal mesh. -The box and the mesh hold the soil in place. Now poke the stems of the succulent bud through the mesh into the soil. Leave the frame lying flat in a cool, bright place till the stems take root. Your beautiful vertical garden is ready. Also Read – Over 2 hours screen time daily will make your kids impulsive-Recycle plastic bottles: It is another DIY project where the used plastic bottles are recycled into pots as creative and fun vertical garden. You need 2-3 plastic bottles, soil, seedlings, string, cardboard and a needle. For the opening, cut a rectangle in the middle of the bottle. -Poke small holes with the help of a needle on the opposite side of the bottle. Line the inner sides of your bottle with cardboard, leaving the holes open. Now add the soil, put the seedlings and water it. Determine the length of the vertical garden and accordingly cut the strings and tie it to the bottle. Hang it at the desired place. -Hanging vertical garden: This vertical suspended garden will give your home a new freshness and decoration which is required around this festive season. To hang the pots, you can choose macrame pendants, this is a trending fashion for suspended gardens and looks very decorative. To alternate this method, you can also go for small wooden shelves where you can place the pots, and holding them with a thick cord of the sailor type will give a beautiful effect in your living space. You can use this method to harvest your own fresh herbs right in your kitchen. -Magnet the plants: This is a very sweet and a simple way to add some bloom to your walls. All you need are some container, preferably of the same shape, paint, washi tape, soil, a small flower plant and a magnet. Take the empty containers and paint them with bright colours and decorate it with washi tapes. Fix 3-4 magnets behind the container with the help of hot glue. You can now easily hang these small pots on any magnetic surface and add a splash of colours to your house. These structures enable space management and also decorate the interiors of houses. You can discover your own unique way to make a vertical garden right inside your house.last_img read more

Continue reading »