Atomic Energy of Canada Limited

About: Atomic Energy of Canada Limited is a company organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Neutron & Zirconium alloy. The organization has 4845 authors who have published 4826 publications receiving 102951 citations.

Groundwater transport of a salt tracer through a sandy lakebed1

Abstract: In an investigation of groundwater advection and dispersion in a lakebed, a vertical zone of salt solution was injected between 1.7 and 3 m beneath the shoreline and entered the lake through a large area of lakebed at a reduced concentration. Migration of the tracer pulse and flux to the lake were monitored over a 7- x 8-m area of lakebed by measuring the electrical conductance of water collected from sampling points beneath the lakebed and from seepage meters on the lakebed. The tracer moved horizontally, curved gently upward, and entered the lake through an area of 17 m/sup 2/-an area 5.7 times larger than the initial cross-sectional area of the tracer zone. Seepage flux through the sediment-water interface declined exponentially with offshore distance and averaged 240 m/sup 3/ yr/sup -1/ per meter of shoreline. Results showed that prediction of solute flux from onshore zones of groundwater contamination requires consideration of dispersion (mixing) and the ratio of horizontal to vertical permeability (K/sub h/:K/sub v/). Numerical simulations showed that with increasing K/sub h/:K/sub v/, tracer- or contaminant-entry areas on the lakebed extend over larger areas and are displaced farther offshore. A K/sub h/:K/sub v/ of 10 matched the field observations. Anmore » analytical model indicated that the observed reduction in peak concentration (a decline to 31% of the initial value over a 6-m flow path) would result from values of longitudinal dispersivity as small as 1 cm.« less

Use of Purified Lesion-Recognizing Enzymes to Monitor DNA Repair in Vivo

Abstract: Publisher Summary This chapter focuses on a recent methodological advance, namely, the exploitation of the unique properties of purified lesion-recognizing enzymes as the basis of assays that monitor with superb sensitivity and specificity the repair of DNA lesions in vivo . The chapter describes the assays, presents a comparison of their assets and liabilities and those of conventional assays, and discusses new findings emerging from their use. The chapter presents the substrate specificity—types of lesions detected—of all known enzymes potentially suitable for incorporation into the assays. The chapter also describes the basic enzymatic mechanisms mediating the repair of DNA and highlights the strengths and weaknesses of the conventional assays largely responsible for their elucidation.