To the Editor: A recent article in PNAS by Asikainen and Werle (1) reports on the occurrence and morphology of ferromanganese nodules found in a New Hampshire lake. The authors offer data on the shapes, banding, composition, and distribution of the nodules and crusts. They also state that my paper (2) claims that the morphology of such nodules is controlled by elemental concentrations and that ...

babbitt is a white silvery alloy that composed of tin, lead, copper and antimony. this alloy is the most current bearing alloy in industrial applications. the characteristics of this alloy, such as high wearing resistance and low coefficient of friction, have converted it into a bearing cover. the target of this study is investigation on the effects of alloy elements on wearing and micro-struct...