Nanoparticles shine with customizable color

first_imgEngineers at Harvard have demonstrated a new kind of tunable color filter that uses optical nanoantennas to obtain precise control of color output.Whereas a conventional color filter can only produce one fixed color, a single active filter under exposure to different types of light can produce a range of colors.The advance has the potential for application in televisions and biological imaging, and could even be used to create invisible security tags to mark currency. The findings appear in the February issue of Nano Letters.Kenneth Crozier, associate professor of electrical engineering at the Harvard School of Engineering and Applied Sciences (SEAS), and colleagues have engineered the size and shape of metal nanoparticles so that the color they appear strongly depends on the polarization of the light illuminating them. The nanoparticles can be regarded as antennas similar to those used for wireless communications but much smaller in scale and operating at visible frequencies.The color output of a new type of optical filter depends on the polarization of the incoming light.“With the advances in nanotechnology, we can precisely control the shape of the optical nanoantennas, so we can tune them to react differently with light of different colors and different polarizations,” said co-author Tal Ellenbogen, a postdoctoral fellow at SEAS. “By doing so, we designed a new sort of controllable color filter.”Conventional RGB filters used to create color in today’s televisions and monitors have one fixed output color (red, green, or blue) and create a broader palette of hues through blending. By contrast, each pixel of the nanoantenna-based filters is dynamic and able to produce different colors when the polarization is changed.These filters, dubbed “chromatic plasmonic polarizers” by the researchers, can create a pixel with a uniform color or complex patterns with colors varying as a function of position.To demonstrate the technology’s capabilities, the researchers used nanoparticles to spell out the acronym LSP (short for “localized surface plasmon”). With unpolarized light or with light that is polarized at 45 degrees, the letters are invisible (gray on gray). In polarized light at 90 degrees, the letters appear vibrant yellow with a blue background, and at 0 degrees the color scheme is reversed. By rotating the polarization of the incident light, the letters then change color, moving from yellow to blue. “What is somewhat unusual about this work is that we have a color filter with a response that depends on polarization,” says Crozier.The researchers envision several kinds of applications: using the color functionality to present [different colors in a display or camera, showing polarization effects in tissue for biomedical imaging, and integrating the technology into labels or paper to generate security tags that could mark money and other objects.Seeing the color effects from current fabricated samples requires magnification, but large-scale nanoprinting techniques could be used to generate samples big enough to be seen with the naked eye. To build a television, for example, using the nanoantennas would require a great deal of advanced engineering, but Crozier and Ellenbogen say it is absolutely feasible. Crozier credits the latest advance, in part, to taking a biological approach to the problem of color generation. Ellenbogen, who is, ironically, colorblind, had previously studied computational models of the visual cortex and brought his knowledge of them to the lab.“The chromatic plasmonic polarizers combine two structures, each with a different spectral response, and the human eye can see the mixing of these two spectral responses as color,” said Crozier.“We would normally ask what is the response in terms of the spectrum, rather than what is the response in terms of the eye,” added Ellenbogen.The researchers have filed a provisional patent for their work.Kwanyong Seo, a postdoctoral fellow in electrical engineering at SEAS, also contributed to the research. The work was supported by the Center for Excitonics at MIT, an Energy Frontier Research Center funded by the Office of Basic Energy Sciences in the U.S. Department of Energy’s Office of Science; and Zena Technologies. In addition, the research team acknowledges the Center for Nanoscale Systems at Harvard for fabrication work.last_img read more

Colombia to Extradite Suspected Narcotics Trafficker To Venezuela

first_imgBy Dialogo November 11, 2010 MEXICO CITY – Harold Mauricio Poveda Ortega, a suspected cocaine trafficker, was arrested by Mexican authorities on Nov. 5. Poveda, a Colombian national who goes by the alias “El Conejo,” allegedly is the largest supplier of cocaine to the Beltrán Leyva cartel, according to the Federal Public Security Secretariat (SSP). Poveda, 37, is suspected of trafficking about 150 tons of cocaine into Mexico from 1998-2000, officials said. Poveda, who also used the alias of “Jonder Antonio Nieves Monsalve” to pass for a Venezuelan national, was taken into custody in a southern area of Mexico City. Mexican and United States officials exchanged information about Poveda throughout the investigation, according to the Mexican website Poveda is suspected of acquiring the cocaine from the Revolutionary Armed Forces of Colombia (FARC), officials said, according to the Colombian website El Peru: Shining Path suspected in police officer’s death Mexico: Harold Mauricio Poveda Ortega arrested LIMA, Peru – A police officer was killed and another was injured when suspected Shining Path members attacked a coca eradication team in a rural town in northern Peru, the Interior Ministry said. The attack occurred on Nov. 5 in the area of Guacamayo in the province of Tocache, where the officers and the eradication squad were camping for the night. The attack was in retaliation for the team destroying two makeshift cocaine laboratories in the area, officials said, according to EFE. One police officer was fatally shot in the chest and the second officer suffered a non-lethal injury in the leg by rebels, who didn’t suffer any losses during the raid, the Interior Ministry said. The Shining Path’s remaining members are based in the Upper Huallaga Valley under the command of Florindo Eleuterio Flores Hala, who goes by the alias of “Comrade Artemio,” and in the Valley of the Apurímac and Ene rivers (VRAE region) under the guidance of Víctor Quispe Palomino, alias “Comrade José.” The United States has issued a reward of up to US$5 million for information leading to either man’s capture, EFE reported. SANTO DOMINGO, Dominican Republic – The National Drug Control Directorate (DNCD) has arrested 57 people linked to a nationwide drug trafficking operation. Police seized 262 cocaine bags, 113 of marijuana, 50 of crack, 10 motorcycles, two guns and $17,903 in Domincan Republican pesos (US$484), according to the DNCD. Two men taken into custody are suspected of selling narcotics from a grocery store in La Romana, said Col. Alcides Ramón Rodríguez Veras, a DNCD spokesman, according to the Dominican Republic website Colombia: Army destroys 870 suspected FARC land mines center_img Dominican Republic: 57 arrested on drug-trafficking charges Mexico: Manuel Fernández Valencia arrested BOGOTÁ, Colombia – The Colombian government will extradite suspected narcotics trafficker Walid Makled to his native Venezuela, where he’ll face trial, officials said. President Juan Manuel Santos pledged during a recent meeting with Venezuelan President Hugo Chávez that Makled, who goes by the alias “The Turk,” would be sent to Venezuela, where he is wanted on drug charges. Makled was taken into custody in August in Colombia during a joint operation with the U.S. Drug Enforcement Administration. Makled and his brothers are accused of using the airline they ran as part of an operation to export 10 tons of cocaine monthly. Two years ago, police apprehended Makled’s three brothers after discovering 300 kilograms (660 pounds) of cocaine on a family ranch. Makled also has been charged in Venezuela in connection with the killings of Colombian drug kingpin Wilber Alirio Varela, lawyer and journalist Orel Zambrano and veterinarian Francisco Larrazábal, both Venezuelan nationals. BOGOTÁ, Colombia – The army destroyed 870 anti-personnel mines suspected of belonging to the Revolutionary Armed Forces of Colombia (FARC) in the department of Putumayo. The confiscation and destruction of the weapons, which are suspected of being the property of the FARC’s 32nd front, occurred in the municipality of Puerto Caicedo, according to a military statement. The troops also discovered more than 90 kilograms (198 pounds) of explosive materials and numerous syringes used to inject liquid during the manufacturing of improvised explosive devices, according to the Colombian website El MEXICO CITY – Manuel Fernández Valencia, who is suspected of working with one of the country’s most wanted drug kingpins to traffic eight tons of marijuana into the United States by the end of 2010, has been arrested, officials said. Fernández Valencia, an alleged member of the Sinaloa cartel, was apprehended after a 20-minute confrontation between police and gunmen, according to a Federal Police statement. Police also apprehended seven men suspected of working for the drug cartel, according to the statement. Fernández Valencia is suspected of working with cartel leader Joaquín Guzmán to traffic narcotics into the United States. Fernández Valencia has been sought for extradition by the United States since last year on narcotics-trafficking charges, according to The Associated Press. Guzmán and Ismael Zambada, who allegedly are the leaders of the Sinaloa cartel, are two of the country’s most wanted fugitives. Officials have offered a US$2 million reward for information leading to their locations.last_img read more

On World War II vet’s last day, Dodger Tommy Lasorda was his angel

first_imgOn the night he died this week — one day before his 91st birthday — Clifford Rich got a phone call from the man at the top of his bucket list.Tommy Lasorda.Riddled with cancer, Rich, who grew up idolizing the Brooklyn Dodgers and later the L.A. Dodgers led by Lasorda, lay in his bed at home in Granada Hills with his family at his side.He had been in hospice care for nearly a month and was unable to speak or open his eyes. The only voices he recognized anymore with a slight movement of his lips were his wife and daughters. Until Tommy called.“Hi, Clifford, this is Tommy Lasorda and I’d just like to speak to you for a moment of your time,” L.A.’s ambassador of baseball said.Tommy Lasorda. On the phone for him. Incredible.“You could see dad’s breathing change and his lips move trying to respond,” daughter Laurie Amigo says. “He knew it was Tommy.”• VIDEO: Tommy Lasorda on the phone with World war II vet Clifford Brown How many times had Cliff told his wife, Mary, he’d give a week’s pay to sit and have a cup of coffee with Lasorda — just talk baseball with him.Tell him about all those glorious years when he sat by the radio as a kid in Brooklyn, before TV, and hung on every pitch.How he didn’t miss a game until he turned 18, old enough to enlist in the army and go fight for his country. How scared he was storming Omaha Beach on D-Day and fighting at the Battle of the Bulge.How he kept replaying those old ballgames in his mind to keep his sanity as insanity rained all around him.“They tell me you are a real Dodger fan — the top one, and I’m honored to be talking to you tonight,” Lasorda continued.“I hope this call could make you feel a little better — then I would be very, very proud.”Laurie watched her dad’s face as Lasorda’s words came through the speaker phone. She saw the struggle.He was finally getting his chance to talk with his idol, but he couldn’t speak. The skipper would just have to take it on faith that his greatest fan was hanging on every word.“I hear lots of good things about you and you’ve done something great. You served your country very well and now you are talking to Hall of Fame Manager Tommy Lasorda.”Pure Lasorda. That’s why we love the guy. He’s a walking pep talk. You half expected him to tell Cliff, “Listen, when you meet the big Dodger in the sky, mention my name. He’ll get you good seats.”Lasorda — all bluster and bravado. But not Tuesday night. There were no cameras rolling in Lasorda’s home as he sat in his den and picked up the phone to call Rich to honor a request from his longtime friend Steve Brener. This one was from the heart.“Enjoy whatever time you have left on this Earth and thanks for being a fan,” Lasorda said. “God chose you to live as long as you have and maybe even longer.“You gotta believe, hope and pray. Take care of yourself, Clifford.”A few hours later, Cliff passed on.It takes a lot to leave Tommy Lasorda speechless, but Cliff’s passing only hours after he called shook him. You could tell.He paused and tried to make a joke about Cliff being the only guy he ever called who died after talking to him.It was weak and Lasorda knew it. For once, he was like the rest of us. At a loss for words.“I am so sorry to hear that,” he said, after another long pause. “Please give my sympathy to his family.”It’s a shame they never met. Lasorda would have loved Cliff. Not only because of his war record and bleeding Dodger blue, but because he didn’t know the definition of the word “quit.”When Cliff finally retired as a traffic officer with the Los Angeles Department of Transportation after 30 years, he was the oldest traffic officer in the country at age 83.Yeah, imagine that. Still hopping around intersections downtown directing traffic in his 80s. He had already put in another 30 years as a detective for the Amherst Police Department in New York.“Every morning leaving for work he always had one pocket bulging with change to feed the meter,” says daughter Annette Bentley-Pintor.“He hated giving out tickets but loved traffic duty. Angry or rude motorists never bothered him. He had a job to do, and he was going to do it with a smile.”Her husband couldn’t have had a better sendoff, Mary says. He could finally scratch off the last name on his bucket list.“What a gift to someone on hospice,” she says. “If there was any voice on Earth Cliff would have recognized and wanted to hear, it was Tommy’s.”When his time comes to meet the big Dodger in the sky — somewhere around his 100th birthday, but don’t hold him to that because it could be later — he’ll look Cliff up, Lasorda says.They’ll have that cup of coffee.Dennis McCarthy’s column runs on Friday. He can be reached at [email protected]center_img Newsroom GuidelinesNews TipsContact UsReport an Errorlast_img read more