Abstract: A method of reducing a substrate and a system for reducing a substrate are described herein. The method comprises contacting the substrate with a catalytic amount of zero valent iron particles and with a reducing agent, wherein the zero valent iron particles mediate transfer of an electron, hydrogen atom and/or hydride ion from the reducing agent to the substrate. The system comprises zero valent iron particles embedded in a porous matrix, wherein the system is configured for contacting the substrate and a reducing agent with a catalytic amount of the zero valent iron particles in the porous matrix.

Abstract: A frequency marker system for indicating the wavelength of light rays, said system comprising: means for collimating said light rays, first and second grating means aligned with at least a portion of said collimated light waves and separated by a distance .DELTA. for providing Moire patterns, means for determining the changes in wavelengths responsive to changes in frequency by determining deflections of the Moire patterns.