Electron micrographs of complementary replicas prepared by either the freeze-fracture or the freeze-etch procedure have often been disappointing. One replica may look excellent whereas the complement, produced simultaneously in the same system, may look worthless. At least part of this complication may be explained by the fact that these replicas retain much of the 3-dimensional contours of the replicated ice surface when dried on a Formvar film. If the desired part of such a replica is oriented in the microscope in such a position that it is vertical to the beam it usually looks good. However, if the desired area happens to be other than vertical to the electron beam, the resultant image may be somewhat distorted if the angle is slight, or may be completely obscurred by electron scattering if the angle is steep.Dog cardiac muscle perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (furnished by Dr. Joaquim Sommer, Duke Univ.) was freeze-fractured at -196° in a Denton DFE-2 Freeze-Etch Unit, shadowed with Pt from a C point, and replicated with C. The replicas were cleaned of biological remains in chromic acid cleaning solution, then mounted on Formvar support films.
Ground-water quality, water year 1995, and statistical analysis of ground-water-quality data, water years 1994-95, at the Chromic Acid Pit site, US Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas