Iowa State University description

Detailed descriptions of the two- disposal pits located at the Horticulture and Agronomy farms at Iowa State University, Ames, lA, have already been published Q). Brief summaries of the constructions and operations are presented below for those who do not have easy access to that report ( 1). 

Taylor, C.R. (1993). A description of AGSIM An econometric-simulation model of regional crop and national livestock production in the United States. In C.R. Taylor, K. Reichelderfer, and S. Johnson, eds., Agricultural Sector Models for the United States Description and Selected Policy Applications. Ames, Iowa Iowa State University Press. 

Tetrachlorodibenzo-p-d1oxin (TCDD). At the detection limit of ten parts per trillion, no TCDD was found in the effluents from the combustion of coal in three different boilers at the Ames power plant (see summary table in reference 16 for description of boilers). This observation was confirmed at a second smaller coal-fired power plant located at Iowa State University. Even when the coal fuel was supplemented with RDF, which should contain the precursor compounds, no dioxins were observed in the vapor and particle samples taken from the effluents. Thus no de novo synthesis occurred during the combustion of coal alone and if dioxins were formed from precursor compounds in the co-combustion of coal and RDF, they were destroyed in the efficient combustion as explained above for the thermal destruction of the PCBs present in the RDF. 

To our knowledge, apart from a brief and elementary outline of a new approach developed by the present authors (5), no simple systematic didactic method for accomplishing the aforementioned goals has been reported (particularly for polyatomic molecules). While excellent introductory descriptions of bonding concepts exist (6,7), no attempts seem to have been made to find a pictorial substitute for a substantial portion of group theory as applied to molecular orbitals or to elaborate in detail the equivalence of the localized and delocalized bonding views on an elementary level. Our approach has been developed and tested in a freshman chemistry course for majors at Iowa State University for a number of years. In the present paper we give and justify a more elaborate discussion of this pictorial method which leads to delocalized and localized MO s for a wide variety of polyatomic molecules. The key concept is that delocalized and localized MO s can be deduced from an appropriate extension of the characteristics of AO s. More specifically, the symmetry and directional characteristics of MO s are obtained from the symmetry and directional characteristics of AO s. 

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