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Researcher pushes limit of when water will freeze。
Though it is one of the great mysteries of science, the transformation of water into ice often escapes people's minds as it is just assumed that's what happens. But how and why it happens is the subject of intense scrutiny by ice scientists like Hadi Ghasemi, Cullen Associate Professor of Mechanical Engineering at the University of Houston. In order to watch the process of crystallization of water into ice at the molecular level, Ghasemi is reporting the best look yet at the process: water-ice phase transformation down to 2 nm (nanometers) in diameter.。
Then when Ghasemi examined these tiny particles, he made another discovery. He could break the limit of when water freezes and maintain the tiny droplets as liquid by putting them in contact with soft interfaces, like gels or lipids.。
"We found that if a water droplet is in contact with a soft interface, freezing temperature could be significantly lower than hard surfaces. Also, a few-nanometer water droplet could avoid freezing down to -44 C if it is in contact with a soft interface," Ghasemi reports in Nature Communications.。
The limit of freezing temperature of a water droplet is -38 C. That is, any water droplet will freeze at some temperature between 0 C to -38 C. Below this temperature, freezing has been inevitable, until now.。
The process of freezing such a tiny water droplet plays a critical role in the survival of animals in cold environments as a frozen water droplet inside a cell leads to the rupture of the cell and death. The process also plays a key role in climate prediction, cloud conditions, cryopreservation of organs and technologies exposed to icing conditions such as aircraft and wind turbines.。
"Experimental probing of freezing temperature of few nanometer water droplets has been an unresolved challenge. Here, through newly developed metrologies, we have been able to probe freezing of water droplets from micron scale down to 2 nm scale," said Ghasemi.。
Previously Ghasemi created an ice-repelling material for aerospace applications using a new concept called stress localization. His current findings contribute to a greater understanding of natural phenomena and provide guidelines for further design of anti-icing systems for aviation, wind energy and infrastructures and even cryopreservation systems.。
Countdown to Beijing 2022******
LISBON, Oct. 19 (Xinhua) -- Portugal expects to have its best performance and its largest delegation ever at the Beijing 2022 Olympic Winter Games, according to Pedro Farromba, member of the Portuguese Olympic Committee (COP) and President of the Federation of Winter Sports of Portugal.
"We have a long friendship with China, and these Games will be a milestone. It will be the biggest Winter Olympics of all time because we trust China's organizational capacity, logistics, infrastructure, and quality of facilities," he said in a joint interview with Chinese media.
According to Farromba, Portugal's preparations have been difficult due to pandemic-related restrictions, with many changes and cancelations to schedules.
"We have no idea of the exact number of athletes that we are going to take. It is very difficult to develop in our country a sport that is not linked to the sun, the beach, and football," he explained.
However, he highlighted that this will be the fifth consecutive edition of the Winter Olympic Games in which Portugal will participate.
"We have a learning path and we have already gained some experience, with financial support from the Portuguese government. We will do our best, even without waiting for medals, but we will fight and represent our country with dignity, developing winter sports in Portugal," said Farromba.
He added that Portugal would this month complete the construction of an ice rink to help develop sports that until now were developed outside the country or on wheel tracks.
Farromba added that he believed the 2022 Winter Olympics in Beijing will be "very safe" despite fears of COVID-19.
"We have had conversations with the Olympic organizing committee that give us great confidence in the event," he said, noting that he agreed with China's decision not to allow spectators from overseas to be present during the Games.
"In competitions, it is always important to have the support of the public. We had the expectation, when the Games were scheduled, to have the support of the Portuguese community in Macao. But we can't have the best scenario in this difficult time we live in," he recalled.
For the member of the COP, the Olympic Games means "hope", and the most important is the "appreciation of the Olympic ideals, fraternity, and healthy competition", he concluded in the interview. Enditem