PHILADELPHIA (AP) — Thousands of scientists, researchers, entrepreneurs and inventors from across the country and around the world are converging in Philadelphia for a national meeting that is the city's largest convention of the summer.

An estimated 14,000 people are expected to attend the five-day American Chemical Society's 244th national meeting and expo, which started Sunday and has a virtually nonstop roster of hundreds of presentations, discussions and other events on its calendar.

Specifics on many of the presentations are not being made public in advance but subjects to be covered range from the use of DNA testing to free innocent prisoners, the relationship between global warming and extreme weather, a cheaper way to make solar panels, and the potential of making household products from food waste.

The event also includes a separate slate of professional development courses and workshops, as well as a career fair and an exposition where more than 200 companies are demonstrating their services, information and equipment.

The American Chemical Society, a trade group for chemical industry professionals, holds two national meetings each year. It last visited Philadelphia in 2008, before the Pennsylvania Convention Center's $786 million expansion completed last year increased meeting and exhibit space by about 60 percent.

According to estimates released by the Philadelphia Convention & Visitors Bureau, the event will generate about $26.5 million in economic benefit to the city and almost 22,000 hotel nights booked.

The American Chemical Society has 164,000 members and calls itself the world's largest scientific society. It was founded in 1876 and has headquarters in Washington, D.C., and Columbus, Ohio.

The group also has a lobbying arm to advocate with members of Congress on issues such as education, copyright, patent and trademark law, public access to federally funded research and a tax credits for research and development.

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Online:

American Chemical Society: http://www.acs.org