Sylvester Stallone seems to have been taken over by his sensitive side. Earlier this summer he declared there would be no more "Rambo" movies, saying he regrets the level of violence in the series; then he decided not to have Rocky Balboa die at the end of the upcoming "Rocky V," concluding it would be too painful for his fans; now, Stallone the artist is going public. The first major exhibit of his paintings is set to open in a Beverly Hills, Calif., gallery Sept. 11, for a 10-day showing. The actor-writer-director has painted for many years, and he uses the medium to help get himself into character by painting interpretations of his film roles. Those canvases are apparently not being shown, but the Hanson Art Galleries on Rodeo Drive describes the paintings it will be exhibiting as "the artist's passionate techniques of palette knife and spray-paint application in which images, graffiti-like words and colors are layered."

Sands for Ol' Blue Eyes

Frank Sinatra has signed an exclusive three-year contract with the Sands Hotel and Casino in Atlantic City, according to the casino. Sinatra will begin honoring the contract with performances early next month. The casino raved, "His playing the Copa Room again will be an event of epic proportions." It was in the Las Vegas Sands's Copa Room, on Oct. 7, 1953, that Sinatra had his first casino showroom performance.

The singer won't have any problem figuring out what to do with all that extra pocket money from his new contract; he and his wife, Barbara, have bought a $3 million house in Malibu, Calif., where they'll have Steven Spielberg, Jack Lemmon and Dustin Hoffman for neighbors. It's the Sinatras' third pied-a`-terre in Southern California.

New Editor at Geographic Journal

National Geographic Research has a new editor. The scholarly quarterly, which is the publishing arm of the National Geographic Society's Committee for Research and Exploration, announced that Anthony R. de Souza will replace founding editor Harm J. de Blij, who has resigned to spend more time on other projects. De Blij was named last week as geography editor of ABC-TV's "Good Morning America." De Souza is an economic geographer who is secretary general of the 27th International Geographical Congress, to be held in Washington in 1992. "De Souza's editorship will continue to reflect National Geographic's longstanding concerns with the myriad of world problems that affect society's quality of life," said Barry C. Bishop of National Geographic.

Paintings Slashed

Three works by American painter Jeff Koons were slashed by a man with a knife at the Venice Biennale arts festival yesterday. According to Giovanni Carandente, a director of the festival, the assailant got away after spraying guards in the face with a chemical substance. There was speculation that the man was offended by the paintings, which depict Koons and Italian Member of Parliament and former porn star Ilona Staller, popularly known as "la Cicciolina."