WASHINGTON, D.C.—The excitement is building to a crescendo here as 40 top high school scientists wait for tonight's gala finale of Intel's Science Talent Search. We've been on hand to live-Twitter and to profile a few projects, everything from Splenda in drinking water to whether parents should discuss their drinking with their kids to cellulosic ethanol.

Here are some more of the highlights:

After wildfires in California, sometimes invasive species can grow back in faster than the native sagebrush; this is one of the reasons that the coastal sage scrub ecosystem has declined by 70 percent over the last 20 years. But Aniruddha (“Ani”) Sandeep Deshmukh, 17, of Bellarmine College Preparatory School in Cupertino, Calif., found that, by applying a specific concentration of a compound called dicobalt edentate to soil, you could reduce the cyanide accumulation that makes such soil more hostile to native sagebrush. This would boost regrowth of native vegetation.

When we spoke to him yesterday, Deshmukh [pictured, above] was looking forward to meeting President Obama, and talking to him about the No Child Left Behind law, which “I generally don’t like”—he wanted a broader evaluation of children, rather than just a focus on test scores. We'll see tonight if he had a chance to speak to the president.

Robot “autonomy” will be the next big advance in robotics, according to Elizabeth Charlotte Coquillette, 18, of Hathaway Brown School in Cleveland Heights, Ohio. For her Intel project, Coquillette built a robot named Leo, who is capable of finding humans when he knows the floorplan of a space. This can be useful in search and rescue missions when it’s too hazardous to send in humans or dogs. Leo requires no instructions from Coquillette after he’s set loose—he “looks” around on his own. (See Coquillette describe her project in this video.)

While Leo doesn’t look much like the Jetsons’ maid or R2D2 (one of the big misconceptions of robotics is that “in the next five years people will all have robots running around their houses” Coquillette says), he is quite advanced. “Even simple tasks, you have to write out completely for a robot,” Coquillette says. She undertook this work at Case Western Reserve University, and plans to continue her studying robotics in college. Her favorite Intel STS experience? Getting an asteroid named after her (an honor extended to all the finalists).

We could soon be learning more about black holes and binary star systems, according to Marianna Yuling Mao, of Mission San Jose High School in Fremont, California. In 2018, a joint venture from NASA and the European Space Agency will launch the Laser Interferometer Space Antenna (known as “LISA”). Mao wanted to discover if LISA would be able to detect the gravitational waves from such celestial entities, and according to models she built using the laws of general relativity, LISA will be picking up these signals. While Mao’s project was in physics, she’s also already building a reputation in math—she recently competed on the US Girls Math Olympiad team in China, winning a bronze medal.

For a long time, scientists thought that carbon nanotubes were virtually insoluble. This was a problem, because these nanotubes—ultrastrong materials—weren’t too useful when they couldn’t be dissolved or combined with other substances. But recently, Philip Vidal Streich, a homeschooled student in Platteville, Wisconsin, discovered that carbon nanotubes can be dissolved under certain circumstances – an advance that has already led to provisional patent filings and the starting of a company called Graphene Solutions with the professor at the University of Wisconsin-Platteville who mentored him. He’s excited about the potential uses for carbon nanotubes and other material science advances he’s working on. One? That holy grail of science fiction—the space elevator (see Streich discuss his project here).

We'll find out who wins tonight, and will be live-Twittering from the gala. Becoming a finalist is no small feat: Over the years, Westinghouse and Intel finalists have grown up to become everything from science Nobel Prize winners (see our "Where Are They Now" profiles of Roald Hoffmann and Leon Cooper) to science-teaching nuns (see our profile of Sister Julia Mary Deiters) and journalists (see profile of Wall Street Journal Numbers Guy Carl Bialik).

Photo of Ani Deshmukh by Laura Vanderkam/copyright Scientific American