Several letters to the editor are presented in response to articles in previous issues including "Application of Ptychography to Visualization of Dislocations in Silicon Single Crystal" in the March 7, 2013 issue, "X-Ray Fluorescence Holography With 50W Low Power X-Ray Source" in the February 28, 2013 issue, and "3D Chemical Mapping With Confocal X-Ray Fluorescence Spectro-Microscopy" in the February 27, 2013 issue.