The method of electron diffraction is used for determining the C–O–C valence angle (α) in 4,4′ diiododiphenyl ether [(C6H4I)2O] and the molecular structures of phosphorus (P4) and arsenic (As4). The electron diffraction photographs were analyzed by four different methods as follows: (1) Visual measurements, (2) measurements of densitometer records, (3) conversion of densitometer records into relative intensity curves, (4) comparison of transformed intensity curves obtained by multiplying the intensity of scattering by [(1/λ) sin θ/2]2 which produces prominent maxima for measurement. The valence angle α was found to be 118±3° for 4,4′ diiododiphenyl ether, definitely greater than the oxygen valence angle found for simpler types of molecules. Phosphorus and arsenic molecules were found to have a regular tetrahedral structure within the limits of experimental error, the atomic separations being 2.21A and 2.44A, respectively, [methods (1) and (2) were used for the case of arsenic]. The minimum atomic distances as found by crystal structure analysis for phosphorus and arsenic are approximately the same as the atomic separations obtained for the gas molecules, showing in addition that these distances do not change greatly when the bond angle decreases from 100° to 60°.

Pulsed nuclear magnetic resonance has been used to differentiate in vivo between normal mouse tail tissue and a malignant transplanted melanoma, S91, located on the tail. The tumor displayed a nuclear (proton) spin-lattice relaxation time of approximately 0.7 second contrasted with the simultaneously measured normal tail tissue relaxation time of approximately 0.3 second.

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Dispersal and deposition of pollen of creeping bentgrass (Agrostis stolonifera L.) was estimated by using CALPUFF, a complex model originally developed to simulate dispersal of particulates and other air pollutants. In field experiments, peak pollen emission rates (8 × 106 pollen grains per min per m2 of a creeping bentgrass stand) occurred between 1000 and 1200 h. Pollen survival under outdoor conditions decreased exponentially with time, and only 1% survived for 2 h. CALPUFF simulations showed deposition of 100,000 viable pollen grains per m2 at distances of 2 to 3 km from the source field, and deposition of one pollen grain per 10 m2 at distances of 4.6 to 6.7 km from the source field. Pattern of simulated deposition varied with weather conditions and, to a lesser extent, source field size. Simulation of dispersal by a small thermal vortex produced deposition of one grain per 10 m2 at 15.3 km from the source field. Overall, the deposition modeling results suggest that pollen‐mediated gene flow is likely at distances of 2 to 3 km from a source field, and possible at distances up to 15 km.

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