Concepts of Soil Formation and Classification in Arctic Regions

Discusses, on basis of studies in northern Alaska, soil forming processes in arctic regions and considers the relation between vegetation and soils and problems of classification and mapping. Tundra soils are poorly drained, mineral in nature, and underlain by permafrost at depths of 1-2 ft Arctic brown soils form under free drainage, are mineral in character, and confined to ridges, terrace edges, and stabilized dunes. The active layer in such soils is usually deep. Downslope movement and frost action tend to disrupt any orderly morphology in both wet and well-drained sites. Moisture conditions in arctic soils exert a marked selective influence on vegetation.--from SIPRE

Picoliter drop-on-demand dispensing for multiplex liquid cell transmission Electron microscopy

Liquid cell transmission electron microscopy (LCTEM) provides a unique insight into the dynamics of nanomaterials in solution. Controlling the addition of multiple solutions to the liquid cell remains a key hurdle in our ability to increase throughput and to study processes dependent on solution mixing including chemical reactions. Here, we report that a piezo dispensing technique allows for mixing of multiple solutions directly within the viewing area. This technique permits deposition of 50 pL droplets of various aqueous solutions onto the liquid cell window, before assembly of the cell in a fully controlled manner. This proof-of-concept study highlights the great potential of picoliter dispensing in combination with LCTEM for observing nanoparticle mixing in the solution phase and the creation of chemical gradients