NINA CHANEL ABNEY, “Class of 2007,” 2007 (acrylic on canvas).   ONE OF THE MOST STRIKING PAINTINGS in the exhibition “30 Americans” is by Nina Chanel Abney. It’s a compelling work, depicting her MFA class at Parsons School of Design in New York. The artist envisions herself as a bespectacled, gun-toting blonde; Her classmates don...