Soil Aeration in Relation to Growth of Tomatoes

It is a well-known fact that forced aeration is beneficial, even essential for plants growing in solutions. It has also been reported beneficial for soil grown plants on various occasions. However, these reports are usually based on the appearance and yield of the mature plants. Information on the plant responses to aeration throughout the growing period is more limited. Clark and Shive in 1932 found that tomatoes grown in nonaerated nutrient solutions started flowering and fruiting somewhat earlier than the aerated controls, although later the aerated plants gave a much greater yield of fruit. Durell in 1941, also working with tomatoes in solution cultures, reported that at the beginning of fruiting the yield from aerated and nonaerated plants was about the same, but that later the aerated plants greatly surpassed the others in the total yield of fruit. These reports suggest that aeration is not equally beneficial at all stages of growth. It therefore seemed desirable to conduct an experiment with plants growing in soil to find the effect of aeration at early and late stages of the ontogeny of the tomato

Methodological and Validation Study of Seed Reserves in Desert Soils

The development of a method for separating seeds from desert soils, and enumerating them, is described. In the Great Basin desert, species differed greatly in their depth distribution, some having a peak at or just below the surface, while others were still abundant below 5 cm. Much higher seed densities were found beneath the canopies of shrubs and of tussock grasses than in the inter-spaces; no consistent differences were found, however, associated with the species of the canopy plant, or with distance from its center. Tentative estimates are given of the seed population in the four validation sites in Curlew Valley

Performance of plastic electron optics components fabricated using a 3D printer

We show images produced by an electron beam deflector, a quadrupole lens and a einzel lens fabricated from conducting and non-conducting plastic using a 3D printer. Despite the difficulties associated with the use of plastics in vacuum, such as outgassing, poor conductivity, and print defects, the devices were used successfully in vacuum to steer, stretch and focus electron beams to millimeter diameters. Simulations indicate that much smaller focus spot sizes might be possible for such 3D-printed plastic electron lenses taking into account some possible surface defects. This work was motivated by our need to place electron optical components in difficult-to-access geometries. Our proof-of-principle demonstration opens the door to consider 3D-printed electron microscopes, whose reduced cost would make such microscopes more widely available. Potentially, this may have a significant impact on electron beam science and technology in general and electron microscopy in particular

Performance of plastic electron optics components fabricated using a 3D printer

We show images produced by an electron beam deflector, a quadrupole lens and a einzel lens fabricated from conducting and non-conducting plastic using a 3D printer. Despite the difficulties associated with the use of plastics in vacuum, such as outgassing, poor conductivity, and print defects, the devices were used successfully in vacuum to steer, stretch and focus electron beams to millimeter diameters. Simulations indicate that much smaller focus spot sizes might be possible for such 3D-printed plastic electron lenses taking into account some possible surface defects. This work was motivated by our need to place electron optical components in difficult-to-access geometries. Our proof-of-principle demonstration opens the door to consider 3D-printed electron microscopes, whose reduced cost would make such microscopes more widely available. Potentially, this may have a significant impact on electron beam science and technology in general and electron microscopy in particular