A child stops by a large print at a photographic memorial for those killed in the confrontation between Ukraine's military and the pro-Russia separatist forces in Sievierodonetsk, Luhansk region, eastern Ukraine, Wednesday, February 23, 2022. Ukraine urged its citizens to leave Russia, and Europe braced for further confrontation Wednesday after tensions escalated dramatically when Russia's leader received authorization to use military force outside his country and the West responded with a raft of sanctions. (Photo by Vadim Ghirda/AP Photo)

A Belarusian law enforcement officer approaches women, who react while sitting on the pavement during a rally of opposition supporters following the presidential election in Minsk, Belarus on August 10, 2020. Belarusian police clashed with protesters on Monday after the opposition accused President Alexander Lukashenko of rigging his re-election victory amid a chorus of criticism from Western leaders. (Photo by Vasily Fedosenko/Reuters)

Groundhog Club co-handler Al Dereume holds Punxsutawney Phil, the weather prognosticating groundhog, in front of the crowd gathered for the 133rd celebration of Groundhog Day on Gobbler's Knob in Punxsutawney, Pa. Saturday, February 2, 2019. Phil's handlers said that the groundhog has forecast an early spring. (Photo by Gene J. Puskar/AP Photo)

Fires approach a home near Lower Lake, Calif., Friday, July 31, 2015. A series of wildfires were intensified by dry vegetation, triple-digit temperatures and gusting winds. The golden hills of California were being blackened Friday by a series of wildfires egged on by bone-dry vegetation, triple-digit temperatures and gusting winds. (Photo by Jeff Chiu/AP Photo)

This photo taken November 10, 2015 shows homeless street children sleeping in a park in Manila. The Philippines has swept 20,000 homeless from the streets, cancelled hundreds of flights and declared public holidays in Manila to ensure a safe and efficient summit of 21 world leaders next week, officials say. (Photo by Jay Directo/AFP Photo)

A man hugs a child at the Santuario de Nuestra Senora de Guadalupe during a celebration on the Virgin of Guadalupe Day in Guatemala City, December 12, 2015. According to Catholic believers, December 12 marks the anniversary of the apparition of the Virgin of Guadalupe at the Cerro del Tepeyac in Mexico. (Photo by Jorge Dan Lopez/Reuters)

An athlete pulls a 15-tonne truck during a Truck-Pull event marking the upcoming Independence Day in the Belarus capital Minsk, on July 3, 2014. The former Soviet nation celebrates its Independence Day on July 3 in memory of the end of Belarus occupation by Nazi Germany troops during the Red Army main summer offensive in 1944. (Photo by Sergei Gapon/AFP Photo)

The lightest material ever made has been produced by a team of scientists in China, a Chinese university announced.