Nonexchangeable ammonium in soils following applications of nitrogen-15-labeled fertilizers

Ammonium (NH[subscript]4[superscript]+) fixation is the trapping of NH[subscript]4[superscript]+ ions within clay lattices. This reaction may temporarily render fertilizer N unavailable to plants and nitrifiers. Although NH[subscript]4[superscript]+ fixation has been studied under laboratory conditions, there is a lack of information on NH[subscript]4[superscript]+ fixation and its importance under field conditions on timescales of interest for crop production. This dissertation describes results from several studies using nitrogen-15-labeled urea and anhydrous ammonia (NH[subscript]3) fertilizers applied to field soils. The objectives were to determine amounts of fertilizer N found as nonexchangeable (fixed) NH[subscript]4[superscript]+ throughout the growing season and to acquire a better understanding of NH[subscript]4[superscript]+ fixation and release under field conditions. Associated studies report the effects of long-term soil management practices on NH[subscript]4[superscript]+ quantity/intensity (Q/I) relationships in Iowa soils;The amounts of fertilizer N found as nonexchangeable NH[subscript]4[superscript]+ were highly variable, even without adjacent soils in a toposequence. Environmental factors such as soil moisture content and rainfall amounts greatly affected amounts of fixation. Concentrations of fertilizer-derived exchangeable and nonexchangeable NH[subscript]4[superscript]+ were highly correlated in NH[subscript]3-fertilized soils at 10 days after application of NH[subscript]3. Concentrations of fertilizer-derived exchangeable and nonexchangeable NH[subscript]4[superscript]+ in urea-fertilized soils were also highly correlated within and across soils. These results suggested a period of net fixation when exchangeable NH[subscript]4[superscript]+ concentrations were high, followed by a period of net release after depletion of exchangeable NH[subscript]4[superscript]+ by nitrification or other processes;Studies of NH[subscript]4[superscript]+ Q/I relationships in long-term rotation plots showed that indexes of NH[subscript]4[superscript]+ availability based on Q/I relationships were similar to those based on measurements of exchangeable NH[subscript]4[superscript]+. Furthermore, long-term soil management practices did not significantly affect the affinity of the soil exchange complex for NH[subscript]4[superscript]+;Overall, the results indicated that NH[subscript]4[superscript]+ fixation is an important transformation of N fertilizers in some Iowa soils. The nonexchangeable NH[subscript]4[superscript]+ is transitory and concentrations decrease throughout the growing season. Amounts of fixation are highly variable and depend upon environmental conditions following fertilizer application. Ammonium fixation is a reaction that deserves more attention in studies of fates and transformations of N fertilizers

Effect of dose rate on ion beam mixing in Nb-Si

The influence of dose rate, i.e., ion flux, on ion beam mixing in Nb‐Si bilayer samples was measured at room temperature and 325 °C. At the higher temperature, an increase in dose rate of a factor of 20 caused a decrease in the thickness of the mixed layer by a factor of 1.6 for equal total doses. At room temperature, the same change in flux had no effect on mixing. These results are consistent with radiation‐enhanced diffusion theory in the recombination‐limited regime

EVALUATING OPTIMAL PRODUCT MIX USING DYNAMIC SIMULATION: A TOMATO PROCESSING CASE

Technology-driven change is everywhere and value-capture from new technology is challenging for business managers. Also rival firms may use technology as part of major success strategies. This situation leads managers to be keenly interested in evaluation of alternative technologies prior to making a sunk investment in physical facilities. In contemplating new or added-capacity processing facilities, managers and investors must evaluate return on investment (ROI). Evaluation of ROI is complex because it varies by alternative technology and the resultant potential product mix alternatives associated with that technology at the time the investment capital is committed to build the processing plant. This research examines optimal alternative product mix from a processing plant technology that is fixed at the time of commitment to building or adding capacity. Evaluating the optimal product mix is of vital concern in any start-up processing environment. In this research the optimal product mix is evaluated by using a sophisticated evaluative tool known as PowerSim. This economic simulation software is used to model a start-up tomato processing plant in Ohio. The model evaluates the effects of various output, or tomato product mix, on plant profitability measured by ROI. Results indicate that an increase in plant profitability is expected when the tomato product mix consists of products that have a lower soluble solids concentration. The lower the soluble solids concentration of a tomato product, the less the processor will benefit from tomato varieties with high soluble solids. The processing operation achieves a RIO of 26.5 percent when the plant'Â’s product mix is 50 percent tomato paste (31 degrees brix) and 50 percent diced tomatoes. This product mix optimizes processor net income and realizes a plant return on equity of 50.6 percent.Agribusiness,

Interact with Speciknee: A Software Tool for Design of Simple Four-bar Prosthesic Knee Joints

This poster and interactive demonstration presents an educational computer design tool which could enable prosthetists and mechanical designers to tailor the motion of low-cost, four-bar prosthetic knees to the sizes and needs of individual amputees. In designing a prosthetic knee joint, it is important to control the position of the lower leg in three angles of flexion and to control its center of rotation in the standing position. In 2010 [1] this problem was analyzed using vector methods, and an algorithm was written which produced curves displaying pivot locations which solve the problem exactly. Since then, a software tool called Speciknee has been developed by building on the core vector computational method and adding a user-friendly operator interface through which a designer could input individual patient needs, select pivot points along the set of curves where prosthetic joint pivots could be placed, and animate the mechanism. [1] Thompson, Thomas J., 2010, Specification of Prosthetic Knee Kinematic Design Parameters Using a Three-position, Instant-center Specification Approach, paper No. IMECE2010-38645, Proceedings of the ASME International Mechanical Engineering Congress and Exposition, Vancouver, British Columbia, Canada, November

Preliminary Report on Conodonts of the Meramecian Stage (Upper Mississippian) from the Subsurface of Western Kansas

Conodonts are microscopic toothlike and platelike structures belonging to an extinct, unknown group of marine animals which probably were bilaterally symmetrical, soft bodied, and free swimming. These fossil structures range from a fraction of a millimeter to about three millimeters in length. They are composed chiefly of calcium phosphate, are either amber or grayish black in color, and are translucent to opaque. Conodonts, known to range from the Lower Ordovician into the Upper Triassic, have a world-wide distribution and have been found to be a useful tool to the stratigraphic paleontologist, despite the fact that there has been little unanimity on the zoological affinity of the animal that bore the conodonts, or on the function that was performed by these structures (Hass, 1962). Conodonts are good index fossils because they are durable, abundant, distinctive, and widespread in their geographic distribution yet restricted in their stratigraphic ranges. Because they are minute, conodonts are well suited for subsurface investigation. They provide a relatively dependable means of correlating different lithologies of biostratigraphic equivalents

Preliminary Report on Conodonts of the Meramecian Stage (Upper Mississippian) from the Subsurface of Western Kansas

Conodonts are microscopic toothlike and platelike structures belonging to an extinct, unknown group of marine animals which probably were bilaterally symmetrical, soft bodied, and free swimming. These fossil structures range from a fraction of a millimeter to about three millimeters in length. They are composed chiefly of calcium phosphate, are either amber or grayish black in color, and are translucent to opaque. Conodonts, known to range from the Lower Ordovician into the Upper Triassic, have a world-wide distribution and have been found to be a useful tool to the stratigraphic paleontologist, despite the fact that there has been little unanimity on the zoological affinity of the animal that bore the conodonts, or on the function that was performed by these structures (Hass, 1962). Conodonts are good index fossils because they are durable, abundant, distinctive, and widespread in their geographic distribution yet restricted in their stratigraphic ranges. Because they are minute, conodonts are well suited for subsurface investigation. They provide a relatively dependable means of correlating different lithologies of biostratigraphic equivalents

The Impact of Fantasy Football on the NFL Fan: Exploring Differences between the Fantasy Football Participant and the Traditional Fan

Fans of the National Football League (NFL) often identify themselves not only with a specific team but also in terms of a broader social group, fantasy football participant. This research utilizes a social identity perspective and data collected from an online context to compare those fans with a team-specific identity to those who also actively participate in fantasy football. Our results show that fans often form a dual identity with the league and the team. This is an important consideration for managers, because while previous research shows that fantasy football participants may attend more games, social identity theory suggests that fan behavior may change. A dual identity can have a negative impact on local teams as fans may increasingly adopt the low cost superordinate identity, watching league games at home, versus the high cost subordinate identity, watching games in the stadium