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Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Effects Of Three Vesicular-Arbuscular Mycorrhizal Fungi On Sweetgum Seedlings From Nine Mother Trees, Richard C. Schultz, Paul P. Kormanik, William C. Bryan
Effects Of Three Vesicular-Arbuscular Mycorrhizal Fungi On Sweetgum Seedlings From Nine Mother Trees, Richard C. Schultz, Paul P. Kormanik, William C. Bryan
Richard C. Schultz
Soil in microplots was infested with three vesicular-arbuscular (VA) symbionts then sown with seed of half-sib progeny from nine sweetgum mother trees. The VA treatments were Glomus fasciculatus, Glomus spp. (a mixture containing both Glomus mosseae and Glomus etunicatus), or a VA mixture of several fungi from the genera Glomus and Gigaspora. Before the seed was sown, all plots had calcium standardized and received an application of commercial fertilizer. During the growing season, NH4NO3 was applied to all plots in equal portions. Mycorrhizal seedlings with G. fasciculatus were slightly but not significantly larger in both height and root-collar diameter than …
Relative Stability Of Multiple Bonds To Silicon: An Ab Initio Study Of C2sih4 Isomers, Mark S. Gordon, Robert D. Koob
Relative Stability Of Multiple Bonds To Silicon: An Ab Initio Study Of C2sih4 Isomers, Mark S. Gordon, Robert D. Koob
Mark S. Gordon
Ab initio (6-31G*/ /3-21G) SCF calculations have been carried out on 15 isomers with the chemical formula C2SiH4• The isomers include structures with formal double and triple bonds to silicon, as well as carbenes and silylenes, so a direct comparison of these types of species is possible. The isomerization energies provide an opportunity to consider the relative strengths of analogous bonds to carbon and silicon. With the appropriate isodesmic reactions, the stabilizing or destabilizing effects of substituents and strain in three-membered rings both may be investigated.
Structure And Stability Of A Silicon-Carbon Triple Bond, Mark S. Gordon, John A. Pople
Structure And Stability Of A Silicon-Carbon Triple Bond, Mark S. Gordon, John A. Pople
Mark S. Gordon
The stability of the carbon-silicon triple bond in silaethyne is investigated via an analysis of its isomerization to silylidene and through a study of its hydrogenation energy relative to acetylene and silaethylene. It is found that silaethyne is rather unstable in a thermodynamic sense. However, while SCF calculations predict this species to rearrange to its more stable isomer with no barrier, the introduction of perturbation corrections suggests the existence of a small barrier separating the two isomers.
A Survey Of Water Flow In Drainage Ditches And Streams In South Central Minnesota, Clay L. Pierce, Bill Thompson
A Survey Of Water Flow In Drainage Ditches And Streams In South Central Minnesota, Clay L. Pierce, Bill Thompson
Clay L. Pierce
Discharge was monitored on 13 agricultural drainage ditches and 4 small rivers in south central Minnesota. Derived data were categorized by response to hydrologic events and stream order. Stream order was found to be the most reliable predictor of hydrologic event response. Peak flows in drainage ditches were found to correspond to peak flows in rivers.
Expansion Approach To Photodissociation Dynamics. I. Theory, Kazuo Takatsuka, Mark S. Gordon
Expansion Approach To Photodissociation Dynamics. I. Theory, Kazuo Takatsuka, Mark S. Gordon
Mark S. Gordon
We propose a new formulation for a photodissociation process to which an expansional (or algebraic) quantum‐variation‐method of scattering is applicable. By solving a ’’full collision’’ problem which describes a multichannel process on the repulsive surface, the photodissociation scheme takes account of interchannel coupling from the outset. Our expression for the amplitude of the partial linewidth is similar to that of the ’’half‐collision’’ approximation of Jortner e t a l. The present formalism differs in that the scattering wave functions take acount of interchannel coupling exactly. As a result, only on‐the‐energy‐shell contributions appear in the partial linewidth.
Expansion Approach To Photodissociation Dynamics. Ii. Correction Formula For Linewidth And Numerical Examples For Hcn, Kazuo Takatsuka, Mark S. Gordon
Expansion Approach To Photodissociation Dynamics. Ii. Correction Formula For Linewidth And Numerical Examples For Hcn, Kazuo Takatsuka, Mark S. Gordon
Mark S. Gordon
A correction formula for energy disposal and linewidth of photodissociation dynamics is proposed. This formula was derived from an identity similar to the Kato identity of the scattering theory. Thanks to the correction formula the resultant linewidth turns out to be more accurate and stable even when a relatively poor basis set is used. Numerical examples for assumed direct dissociation of HCN, DCN, and TCN and for the predissociation of HCN and DCN are presented.