World's most heat resistant material found

December 25, 2016

London, Dec 25: Scientists have identified materials that can withstand temperatures of nearly 4,000 degrees Celsius, an advance that may pave the way for improved heat resistant shielding for the faster-than-ever hypersonic space vehicles.heat

Researchers from Imperial College London in the UK discovered that the melting point of hafnium carbide is the highest ever recorded for a material.

Tantalum carbide (TaC) and hafnium carbide (HfC) are refractory ceramics, meaning they are extraordinarily resistant to heat. Their ability to withstand extremely harsh environments means that refractory ceramics could be used in thermal protection systems on high-speed vehicles and as fuel cladding in the super-heated environments of nuclear reactors.

However, there has not been the technology available to test the melting point of TaC and HfC in the lab to determine how truly extreme an environment they could function in. The researchers developed a new extreme heating technique using lasers to test the heat tolerance of TaC and HfC.

They used the laser-heating techniques to find the point at which TaC and HfC melted, both separately and as mixed compositions of both.

They found that the mixed compound (Ta0.8Hf0.20C) was consistent with previous research, melting at 3,905 degrees Celsius, but the two compounds on their own exceeded previous recorded melting points. The compound TaC melted at 3,768 degrees Celsius, and HfC melted at 3,958 degrees Celsius.

The findings may pave the way for the next generation of hypersonic vehicles, meaning spacecraft could become faster than ever.

"The friction involved when travelling above Mach 5 -hypersonic speeds - creates very high temperatures," said Omar Cedillos-Barraza, currently an Associate Professor at the University of Texas.

"So far, TaC and HfC have not been potential candidates for hypersonic aircraft, but our new findings show that they can withstand even more heat than we previously thought - more than any other compound known to man," said Cedillos-Barraza, who carried out the research as a PhD student at Imperial College London

"This means that they could be useful materials for new types of spacecraft that can fly through the atmosphere like a plane, before reaching hypersonic speeds to shoot out into space," he said.

"These materials may enable spacecraft to withstand the extreme heat generated from leaving and re-entering the atmosphere," he added.

Examples of potential uses for TaC and HfC could be in nose caps for spacecraft, and as the edges of external instruments that have to withstand the most friction during flight.

Currently, vehicles going over Mach 5 speeds do not carry people, but Cedillos-Barraza suggests it may be possible in
the future.

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News Network
July 24,2020

Melbourne, Jul 24: Home-made cloth face masks may need a minimum of two layers, and preferably three, to prevent the dispersal of viral droplets associated with Covid-19, according to a study.

Researchers, including those from the University of New South Wales in Australia, noted that viral droplets are generated by those infected with the novel coronavirus when they cough, sneeze, or speak.

As face masks have been proven to protect healthy people from inhaling infectious droplets as well as reducing the spread from those who are already infected, several types of material have been suggested for these, but based on little or no evidence of how well they work, the scientists said.

In the current study, published in the journal Thorax, the researchers compared the effectiveness of single and double-layer cloth face coverings with a surgical face mask (Bao Thach) at reducing droplet spread.

They said the single layer covering was made from a folded piece of cotton T shirt and hair ties, and the double layer covering was made using the sew method described by the US Centers for Disease Control and Prevention (CDC).

The scientists used a tailored LED lighting system and a high-speed camera to film the dispersal of airborne droplets produced by a healthy person with no respiratory infection, during speaking, coughing, and sneezing while wearing each type of mask.

Their analysis showed that the surgical face mask was the most effective at reducing airborne droplet dispersal, although even a single layer cloth face covering reduced the droplet spread from speaking.

But the study noted that a double layer covering was better than a single layer in reducing the droplet spread from coughing and sneezing.

According to the researchers, the effectiveness of cloth face masks is dependent on the number of layers of the covering, the type of material used, design, fit as well as the frequency of washing.

Based on their observations, they said a home made cloth mask with at least two layers is preferable to a single layer mask.

"Guidelines on home-made cloth masks should stipulate multiple layers," the scientists said, adding that there is a need for more research to inform safer cloth mask design.

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News Network
February 5,2020

Feb 5: Tesla is making Elon Musk a lot richer without paying him a dime.

A blistering stock rally has bolstered the value of CEO Musk's 19% stake in the electric car maker by $16 billion since the start of 2020, to $30 billion.

Tuesday's steep climb in the share price could sweeten Musk's payday under his record-breaking compensation package, which is built on stock options that rely on market value targets. Two milestones have now been achieved that could see Musk unlock options worth $1.8 billion.

The controversial chief executive, who is also the majority owner and CEO of rocket maker SpaceX, recently testified that he did not have a lot of cash as he successfully defended himself in a defamation lawsuit. He previously has taken loans using his Tesla shares as collateral.

Musk does not take a salary, choosing instead a risky options package that envisions the stock market value of Tesla rising to $650 billion over 10 years, a prospect that was derided by some investors when the deal was announced in 2018.

That target now looks less crazy. Shares of Tesla have rallied over 50% since the company posted its second consecutive quarterly profit last Wednesday, which was viewed as a major accomplishment for a company competing against established automotive heavyweights including General Motors Co  and BMW.

Tesla shares have climbed about 400% since early June, helped by the company's better-than-expected financial results and ramped-up production at its new car factory in Shanghai.

On Tuesday, Tesla surged as much as 24% before falling back in the final minutes of the trading session to end the day up 13.7%. That put its market capitalization at $160 billion, almost twice the combined value of Ford Motor and General Motors.

The shares had also rallied on Monday, partly fueled by Panasonic Corp's 6752.T saying its automotive battery venture with Tesla was profitable for the first time.

The options Musk was awarded in 2018 vest incrementally based on targets for Tesla's stock market value and its financial performance. The market capitalization would have to sustainably rise by $50 billion increments over the agreement's 10-year period, with the full package payout reached if the market cap reaches $650 billion, as well as the company's meeting revenue and profit targets.

Musk is on his way to seeing his first two tranches of options vest. He achieved operational targets on revenue and adjusted earnings last year.

The rise in Tesla's market capitalization last month to a target of $100 billion opened the way for Musk's first tranche of options to vest. With Tuesday's surging share price, the market capitalization blew past the second target of $150 billion, opening the way for the second tranche to vest. Tesla's market capitalization must stay at or above each target level for one- and six-month averages for each set of options to vest.

Tesla was valued at about $52 billion when shareholders approved the pay package in March 2018, a time when the company faced a cash crunch, production delays and increasing competition from rivals.

A full payoff for Musk would surpass anything previously granted to U.S. executives, according to Institutional Shareholder Services, a proxy advisor that recommended investors reject the pay package deal at the time.

Musk currently owns about 34 million Tesla shares, and his compensation package would let him buy another 20.3 million shares if all his options tranches vest.

When Tesla unveiled Musk’s package, it said he could in theory reap as much as $55.8 billion if no new shares were issued. However, Tesla has since awarded stock to employees and last year sold $2.7 billion in shares and convertible bonds, diluting the value of the stock.

Musk has transformed Tesla from a niche car maker with production problems into the global leader in electric vehicles, with U.S. and Chinese factories. So far it has stayed ahead of more established rivals including BMW and Volkswagen.

Many investors remain skeptical that Tesla can consistently deliver profit, cash flow and growth. More Wall Street analysts rate Tesla "sell" than "buy," and the company's stock is the most shorted on Wall Street.

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Agencies
January 19,2020

New Delhi, Jan 19: Messaging service WhatsApp which on Sunday faced issues in transmitting multimedia content including pictures and images, prompting social media users to share hilarious memes and messages, resumed regular services after over two hours.

#WhatsAppDown was the trending hashtag on Twitter for most part of Sunday afternoon in India along with several other countries such as Brazil, Europe and also parts of Middle-East including UAE, reported downdetector.in, a realtime problem and outage monitoring website.

Users of the popular messaging app were unable to send media files, stickers and GIFs.

Most users immediately went to Twitter to find out about the problem and check if others were facing the same issue.

Numerous tweets and memes took over the internet as soon as the news broke about the WhatsApp tech issue. After around two hours of technical glitch, the app resumed full service.

Even after full recovery of media transfer, people globally still continued checking the status of the messaging app.

WhatsApp has been one of the prime messaging apps since May 2009 and has recently collaborated with Facebook.

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