From new underwater drones to preserved roses that have helped lift villagers out of poverty, China's newest technologies and their applications were showcased at the launch of the 17th National Science Week on Saturday in Beijing.

China also will open more than 3,000 universities and scientific facilities during the week for free tours. More than 500,000 visitors are expected to attend the 116 facilities founded by the Chinese Academy of Sciences alone, the academy said on Saturday.

"This year's theme is building a strong nation with science and fulfilling dreams with innovations," Vice-Premier Liu Yandong said at the Cultural Palace of Nationalities in Beijing, where some exhibitions are being held.

Science Week is the largest, longest and most participated in annual science event in China, she said. Since 2001, more than 1.5 billion people have participated in the extravaganza.

More than 260 exhibitions and 22 events will be held in the palace, covering five major fields including life science, new material, information technology, smart manufacturing and deep sea and space exploration, the event calendar says.

May 20, Saturday, also was the "day of love" - the pronunciation of "520" is a homophone for "I Love You" in Chinese.

"It is a great day for science lovers to interact and learn about technologies," said Gu Qingyi, a researcher at the academy's Institute of Automation. "As people are having fun, we hope they get interested in the science behind all the cool gadgets."

At the palace's science interaction section, adults and children played games on virtual and augmented reality headsets. For those who prefer hands on activities, they can learn in simulators how to operate Jiaolong - China's manned deep-sea research submersible - or a 360-degree rotating pilot training pod. For relaxation, they can touch a live starfish or a horseshoe crab in a fish tank or color a flowerpot using mineral pigments.

"Seeing knowledge from textbooks come alive really helps students become interested in science," said Chen Hongcheng, a teacher at Beijing Yu Cai School, who led a group of elementary students there. "These events can be a relaxing and learning experience, especially seeing how technologies has benefited society."

In the middle of the palace lies the exhibition on how science has helped China's poverty-alleviation effort. It is packed with products from honey made in high-tech beehives to high yielding wheat grown from dry soil.

Zhu Lunfeng, a villager from the mountainous Zhashui county in Shaanxi province, said the provincial science department helped them build a 250 million yuan ($36 million) preserved flower industry that has lifted more than 700 villagers, mostly from Zhujiawan village, out of poverty.

"Preserved flowers are generally very dry and bleak, but scientists helped us create ones that have more humidity and longer shelf life," he said. "Our county is 90 percent mountain and forests, so having a product that is competitive really helps."

Most of the 700 villagers are earning more than 8,000 yuan per year, some even earn 20,000 yuan, which is much higher than the national poverty line, he said.

"Science has changed the fate of my people," he said. "It is '520', so I brought preserved roses from my hometown to show visitors my love for science and the country."

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