Chemical structure of lipid A as found in E. coli. Lipid A is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS), also called endotoxin molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane.
watermark - Computer Definition. 1  A translucent mark or image in paper produced by pressing the paper in a mold or on a processing roll during the manufacturing process. The watermark is visible when the paper is held to a light. A watermark is used as a sign of authenticity in order to make the counterfeiting of currency and postage stamps more difficult, for example.
A page from an existing PDF can also be used as a watermark in a new PDF. Defines how transparent the watermark should be. Use the slider or edit box to define a value between 0 (fully transparent) and 100 (fully opaque). PDF/A files cannot interpret this setting, watermarks appear at full strength (100).