Correction

COLLOQUIUM. For the article “Study of Nd³⁺, Pd²⁺, Pt⁴⁺, and Fe³⁺ dopant effect on photoreactivity of TiO₂ nanoparticles,” by S. I. Shah, W. Li, C.-P. Huang, O. Jung, and C. Ni, which appeared in number 9, April 30, 2002, of Proc. Natl. Acad. Sci. USA (99, 6482–6486; First Published March 5, 2002; 10.1073/pnas.052518299), on page 6482, right column, the sentence beginning on line 15 should read “In this article, we describe the synthesis of TiO₂ nanoparticles and the effect of transition metal ion Nd³⁺, Pd²⁺, Pt⁴⁺, and Fe³⁺ dopants on the photocatalytic activity of TiO₂ nanoparticles.”