In June three students from the same high school in Hubei province each won a gold medal at the Invention and New Product Exposition in Pittsburgh, one of the largest invention trade shows in the United States.

One of the budding Chinese inventors from Wujiashan High School in Wuhan city is Wang Yujie, a 10th-grade student who won gold at the international expo for her invention that enables automatic control of oxygen in fish ponds.

Her childhood was spent in the coastal province Zhejiang and she now lives in an area of Wuhan abundant in rivers, where Wang heard many stories of fish dying from the lack of oxygen at night.

Locals call it a "turn-pond-over incident" as a large number of fish turn over dead in the water.

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"Traditionally, fish breeders increase oxygen in fish ponds by switching on aerators by hand," she told Wuhan Evening News.

If they fail to do so, the fish can die.

Wang's invention solves the problem because it monitors the oxygen level in ponds day and night. Once it senses a shortage, it switches on the aerators.

Another of the medal winners is also in the first year of high school. Xue Jigang's invention is an in-car system that adds an alcohol breathalyzer to the steering wheel and links with the ignition.

"A drinking driver will be caught by the tester," Xue said. "He will receive a voice reminder installed in the system if his alcohol level is beyond the legal limit."

After three reminders, the ignition will be shut down automatically, the inventor added.

Yue Liangjian, a science teacher at the school, told media that Xue is fastidious with detail, a trait highly acclaimed by the judging panel.

The third winner's invention might be less glamorous than his schoolmates, but Zhong Juncheng's idea for an automatic toilet could have the widest application.

"While automatic toilets now available on market are priced at more than 10,000 yuan ($1,611) and still counted as luxuries, Zhong's invention is an add-on to an ordinary toilet at the cost of 200 to 300 yuan," said Yue.

Inventor Zhong told the local newspaper that his inspiration came from an unpleasant experience at a service center on the expressway when his father took him back to his home province Fujian during a summer vacation about a year ago.

"I found some toilets not flushed and stinking. The idea came to me that if I could invent an automatic toilet used in such a public building, the story could be different," he recalled.