'New light-absorbent material to cool buildings, cars'

February 5, 2017

Los Angeles, Feb 5: Scientists have developed a thin, flexible, lightweight material that can block thermal detection and absorb light from every angle to keep buildings and cars cool on hot summer days.

absorbentThe material, developed by engineers at the University of California San Diego in the US, is called a near-perfect broadband absorber.

It absorbs more than 87 per cent of near-infrared light (1,200 to 2,200 nanometre wavelengths), with 98 per cent absorption at 1,550 nanometres, the wavelength for fiber optic communication.

The material is capable of absorbing light from every angle. It also can theoretically be customised to absorb certain wavelengths of light while letting others pass through.

Materials that "perfectly" absorb light already exist, but they are bulky and can break when bent. They also cannot be controlled to absorb only a selected range of wavelengths, which is a disadvantage for certain applications.

Imagine if a window coating used for cooling not only blocked infrared radiation, but also normal light and radio waves that transmit television and radio programmes.

By developing a novel nanoparticle-based design, a team led by professors Zhaowei Liu and Donald Sirbuly at the UC San Diego has created a broadband absorber that is thin, flexible and tunable.

"This material offers broadband, yet selective absorption that could be tuned to distinct parts of the electromagnetic spectrum," said Liu.

The absorber relies on optical phenomena known as surface plasmon resonances, which are collective movements of free electrons that occur on the surface of metal nanoparticles upon interaction with certain wavelengths of light.

Metal nanoparticles can carry a lot of free electrons, so they exhibit strong surface plasmon resonance - but mainly in visible light, not in the infrared.

The researchers reasoned that if they could change the number of free electron carriers, they could tune the material's surface plasmon resonance to different wavelengths of light.

"Make this number lower, and we can push the plasmon resonance to the infrared. Make the number higher, with more electrons, and we can push the plasmon resonance to the ultraviolet region," said Sirbuly.

The problem with this approach is that it is difficult to do in metals. To address this challenge, engineers designed and built an absorber from materials that could be modified, or doped, to carry a different amount of free electrons: semiconductors.

Researchers used a semiconductor called zinc oxide, which has a moderate number of free electrons, and combined it with its metallic version, aluminium-doped zinc oxide, which houses a high number of free electrons — not as much as an actual metal, but enough to give it plasmonic properties in the infrared.

The study was published in the journal Proceedings of the National Academy of Sciences.

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News Network
March 13,2020

Bengaluru, Mar 13: In the wake of fresh cases of Covid-19 reported in Karnataka, Infosys Foundation chairperson Sudha Murty has urged the Karnataka government to take steps to shut malls and theatres, saying the coronavirus multiplies in air-conditioned areas.

In a letter to the government, she said preventive measures should be taken to control the spread of coronovirus before it gets worse.

Murty, who also leads the State government-constituted Karnataka Tourism Task Force, said she has discussed the current situation with Chairman and Executive Director of Narayana Health, Devi Prasad Shetty.

She suggested closure of all schools and colleges with immediate effect, malls, theatres and “all air-conditioned areas where the virus multiplies”, and allow only essential services like pharmacy, grocery and petrol bunks.

“It is not scientifically proven that the virus dies in high temperature,” she said pointing to spread of the virus -- despite heat -- in peak summer in Australia and Singapore, which have “summer all 12 months”.

“I request you to vacate one government hospital with at least 500 - 700 beds for this purpose (to deal with coronavirus cases), which requires oxygen lines and pipes,” she said.

“Infosys Foundation, the philanthropic and CSR arm of software major Infosys, would do the civil work and Devi Shetty has agreed to share resources like medical equipment,” she added.

“We would like to work with the government proactively so that we can prevent this as early as possible,” Sudha Murty said.

The total number of confirmed coronavirus positive cases in Karnataka is five, including the 76-year old man from Kalaburagi who died on Tuesday night.

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Agencies
January 22,2020

New Delhi, Jan 22: "Don't get into a trap. Your security is in your hands," the Border Security Force (BSF) has said issuing its social media rules for its officers and men. It has directed them not to use 42 mobile applications and show caution while using Facebook, Twitter and WhatsApp.

"Be cautious while using social media," said the BSF in a circular issued recently.

"Before using WhatsApp, Facebook, Twitter and other social media platforms, one needs to keep in mind that you are border guarding force and Central Civil Services (Conduct) Rules rule duly are applicable," it said.

It further pointed out that by commenting/writing about or forwarding unverified reports and rumours one violates laws of land.

"Several times unverified reports would be presented in way that they are absolutely true and start believing it. Seeing such post always use your commonsense and never get into the trap (sic.)," it state adding that the anti-national elements uses social media to propagate their agenda to cause unrest in India.

A picture clicked by Border Security Force personnel and posted on a social media platform remains there for always. Therefore, one should use officially approved pictures about any incident or untoward incidents related to Border Security Force, stated the circular. It pointed that unauthorised persons should not engage into taking pictures of the incidents.

It also highlighted how through social media, a few BSF personnel have fallen into trap of espionage racket carried out by enemy countries.

"Our security and respect is in our hands. Always think twice whether you are doing correct by accepting friendship requests from unknown persons, especially women and girls," it cautioned the troopers and officers.

It also highlighted that while going on leave and joining back the force, always follow the rules and regulations laid out for safety and security. "This is for your own safety," it stressed in the end.

The BSF has also issued a list of 42 mobile applications that needs to be completely avoided by serving BSF officers and jawans.

They are MI store, Weibo, Wechat, Shareit, Truecaller, UC News, UC Browser, Beautyplus, NewsDog, Viva Video - QU video Inc, Parallel Space, Apus Browser, Perfect Corp, Virus Cleaner - HI Security Lab, CM browser, MI Community, DU recorder, Vault Hide - No mobile Security, Youcam Makeup, Cachecleaner DU Apps Studio, DU battery saver, DU privacy, 360 security, DU Browser,Clean master - Cheeta Mobile, Baidu Translate, Wonder Camera - Bindu Inc, ES Ifle Explorer, Photo Wonder, QQ international , QQ music, QQ Mail, AA player, QQ News Feed, Wesync, QQ security Center, Selfie City, Mail Master, Mi Video Call -Xaomi and QQ launcher.

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Agencies
March 13,2020

Amid the rapid spread of the novel coronavirus (COVID-19), which has infected 73 people in India and killed more than 4,500 individuals globally, doctors have advised that in addition to regularly washing hands, one should also disinfect their smartphone every 90 minutes with alcohol-based hand sanitizer.

Ravi Shekhar Jha, Head of Department at Fortis Escorts Hospital in Faridabad said the best method to disinfect your smartphone is to use regular doctor spirit or the alcohol-based hand sanitizer at least every 90 minutes.

"Avoid touching your eyes, mouth, or nose. The best option is to use a phone cover or a Bluetooth device and try to touch your phone as less as possible. We would also recommend cleaning your phone at least twice a day," Jha told IANS.

According to research, published in 2018 by Insurance2Go, a gadget insurance provider, revealed that smartphone screens have three times more germs than a toilet seat.

One in 20 smartphone users was found to clean their phones less than every six months, said the study.

"In the time of fear of coronavirus, smartphones should also be disinfected with alcohol-based sanitizer rub. Pour few drops of sanitizer on a tiny clean cotton pad and rub it safely on your entire phone," said Jyoti Mutta, Senior Consultant, Microbiology, Sri Balaji Action Medical Institute in New Delhi.

"You can repeat this process every evening coming back home after an entire day out at work and once in the morning before going out," Mutta added.

"Maintain basic cleanliness, and try to avoid using other's phones especially if suffering from respiratory illness or flu-like symptoms as there is no other way to disinfect these regular gadgets," she stressed.

Another study from the University of Surrey in the UK, also found that the home button on your smartphone may be harbouring millions of bacteria - some even harmful.

The World Health Organisation (WHO) declared the novel coronavirus as a global pandemic on Wednesday. The death toll of COVID-19 has crossed the 4,500 marks and confirmed cases globally have touched one lakh as per the reports.

According to Suranjeet Chatterjee, Senior Consultant in Internal Medicine Department of Indraprastha Apollo Hospitals in New Delhi, "We should frequently wash our hands, cover our coughs and it is important to adapt to other good hygiene habits that are most important in such a situation."

"Coronavirus and other germs can live on surfaces like glass, metal or plastics and phones are bacteria-ridden. It is necessary that we sanitize our hands frequently and make sure that our hands are clean all the time," Chatterjee told IANS.

"The emphasis should be laid on sanitising our hands rather than sanitizing the phone - once in a while the phone can be sanitized under the guidance of the makers of the phone," Chatterjee stressed.

According to the global health agency, the most effective way to protect yourself against coronavirus is by frequently cleaning of your hands with alcohol-based hand rub or washing them with soap and water.

The WHO's report showed the virus infects people of all ages, among which older people and those with underlying medical conditions are at a higher risk of getting infected.

People should eat only well-cooked food, avoid spitting in public, and avoid close contact, the WHO said, adding that it is important for people to seek medical care at the earliest if they become sick.

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