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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Agencies
June 16,2020

Paris, Jun 16: Increasing numbers of readers are paying for online news around the world even if the level of trust in the media, in general, remains very low, according to a report published Tuesday.

Around 20 percent of Americans questioned said they subscribed to an online news provider (up to four points over the previous year) and 42 percent of Norwegians (up eight points), along with 13 percent of the Dutch (up to three points), compared with 10 percent in France and Germany.

But between a third and a half of all news subscriptions go to just a few major media organisations, such as the New York Times, according to the annual Digital News Report by the Reuters Institute.

Some readers, however, are also beginning to take out more than one subscription, paying for a local or specialist title in addition to a national news source, the study's authors said.

But a large proportion of internet users say nothing could convince them to pay for online news, around 40 percent in the United States and 50 percent in Britain.

YouGov conducted the online surveys of 40 countries for the Reuters Institute in January, with 2,000 respondents in each.

Further surveys were carried out in six countries in April to analyse the initial effects of COVID-19.

The health crisis brought a revival of interest in television news -- with the audience rising five percent on average -- establishing itself as the main source of information along with online media.

Conversely, newspaper circulation was hard-hit by coronavirus lockdown measures.

The survey found trust in the news had fallen to its lowest level since the first report in 2012, with just 38 percent saying they trusted most news most of the time.

However, confidence in the news media varied considerably by country, ranging from 56 percent in Finland and Portugal to 23 percent in France and 21 percent in South Korea.

In Hong Kong, which has been hit by months of sometimes violent street protests against an extradition law, trust in the news fell 16 points to 30 percent over the year.

Chile, which has had regular demonstrations against inequality, saw trust in the media fall 15 percent while in Britain, where society has been polarised by issues such as Brexit, it was down 12 points.

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News Network
January 27,2020

Mumbai, Jan 27: The country's largest car maker Maruti Suzuki India (MSI) on Monday said it has increased prices of select models by up to Rs 10,000 with immediate effect to offset the impact of rising input costs.

The price change varies across models and ranges up to 4.7 per cent (ex-showroom Delhi) and are effective from January, 27 2020, MSI said in a statement.

The price of entry level model Alto range has gone up in the range of Rs 9,000-6,000, S-Presso between Rs 1,500 to 8,000, WagonR between Rs 1,500 and Rs 4,000.

The company has also increased the price of its multi purpose vehicle Ertiga between Rs 4,000-10,000, Baleno by Rs 3,000 to 8,000 and XL6 by up to Rs 5,000 (all prices ex-showroom Delhi).

Currently, the company sells a range of vehicles starting from entry-level small car Alto to premium multi purpose vehicle XL6 with price ranging from Rs 2.89 lakh to Rs 11.47 lakh (ex-showroom Delhi).

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Agencies
June 29,2020

New Delhi, Jun 29: Witnessing azure skies and breathable air for the last three months, Delhi on Monday recorded deterioration in its air quality, with particulate matter with diameter of 2.5 and 10 microns -- too small to be filtered out of the human body -- standing at 52 and 297 micrograms per cubic respectively.

Gufran Beig, Project Director of System of Air Quality Weather Forecasting and Research (SAFAR), said that the sudden spike in air pollution is due to a mild dust storm blowing from Rajasthan.

"Since the wind direction is changing and moist air is coming in, the air quality in Delhi will become better by tomorrow," Beig told IANS.

Central Pollution Control Board (CPCB) data showed that the overall air quality near Delhi Technical University (DTU) area stood at 326 micrograms per cubic, followed by 308 at Narela and 307 at Mundka.

Out of 36 stations, the AQI in as many as 30 stations was above 200 micrograms per cubic till 1 pm on Monday.

The System of Air Quality Weather Forecasting and Research categorises air quality in the 0-50 range as good, 51-100 as satisfactory, 101-200 as moderate, 201-300 as poor, 301-400 as very poor, and above 400 as severe.

According to SAFAR's website, "PM 10 (coarser dust particle) is the lead pollutant. AQI is likely to improve to moderate category by tomorrow, and further improvement is expected by July 1."

Researchers indicated that PM 10 and PM 2.5 will be 170 and 47 micrograms per cubic on Tuesday.

With no vehicles plying on the roads or industries shut due to the lockdown since March 25, Delhi's air quality had improved drastically.

According to a study conducted by the Indian Institute of Technology (IIT), Delhi, if the low levels of air pollution reached during the lockdown period are maintained, India's annual death toll could reduce by 6.5 lakh.

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