In DSM, nicotine dependence is included under the general definition of substance dependence.  The essential feature of Substance Dependence is a cluster of cognitive, behavioral, and physiologic symptoms indicating that the individual continues use of the substance despite significant substance-related problems.
The Best Materials to Cover your Greenhouse. 1  Glass: The traditional greenhouse covering, glass is the preferred material for permanence. 2  Film Plastic: Film plastic is one sixth to one tenth of the cost per square foot of a glass covered structure.
Weight of Building Materials. The weight of materials for a DIY small project, hobby greenhouse is probably not going to be a deciding factor, but comparatively, wood and rebar are relatively heavy and PVC pipe is extremely light. Strength of Building Materials. 1  Lumber frame construction is the norm for most construction projects that are 3 stories tall or less and can be designed to meet most building requirements. 2  A greenhouse frame constructed from rebar could also be very strong if the framework were welded and used lots of cross bracing.