15 research outputs found
Phosphorus speciation in cultivated organic soils revealed by P K-edge XANES spectroscopy
Cultivated organic soils make a significant contribution to phosphorus (P) leaching losses from agricultural land, despite occupying a small proportion of cultivated area. However, less is known about P mobilisation processes and the P forms present in peat soils compared with mineral soils. In this study, P forms and their distribution with depth were investigated in two cultivated Histosol profiles, using a combination of wet chemical extraction and P K-edge X-ray absorption near-edge structure (XANES) spectroscopy.Both profiles had elevated P content in the topsoil, amounting to around 40 mmol kg(-1), and P speciation in both profiles was strongly dominated by organic P. Topsoils were particularly rich in organic P (P-org), with relative proportions of up to 80%. Inorganic P in the profiles was almost exclusively adsorbed to surface reactive aluminium (Al) and iron (Fe) minerals. In one of the pro-files, small contributions of Ca-phosphates were detected.A commonly used P saturation index (PSI) based on ammonium-oxalate extraction indicated a low to moderate risk of P leaching from both profiles. However, the capacity of soil Al and Fe to retain P in organic soils could be reduced by high competition from organic compounds for sorption sites. This is not directly accounted for in PSI and similar indices.Accumulation of P-org in the topsoil may be attributable by microbial peat decomposition and transformation of mineral fertiliser P by both microbiota and crops. Moreover, high carbon-phosphorus ratio in the surface peat material in both profiles suggests reduced net mineralisation of P-org in the two soils. However, advancing microbial peat decomposition will eventually lead to complete loss of peat horizons and to mineralisation of P-org. Hence, P-org in both profiles represents a huge potentially mobilised P pool
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Phase transformations of Ni-B coating
The goal of this project was to determine the microhardness values of electroless Ni-B coating during isothermal heat treatments and gain an understanding of the phase transformations that occur. The test matrix ranged from 200?C to 1000?C for various times. Hardness testing was used to determine the amount of time necessary to obtain peak microhardness values. X-ray diffraction determined the ratio of Ni to NiB in each sample. Optical microscopy and SEM analysis helped study the microstructure and failure of samples. EDS analysis helped to determine composition and diffusion. Results show that peak hardness occurs between 550?C and 650?C after 2 hour heat treatments; iron diffuses into the coating which may have caused failure at 850?C; and the concentration of NiB decreases at the surface with increasing time and temperature
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Medieval armor and armored combat
This project collaborated with the Higgins Armory Museum to develop an understanding of armored combat during the 15th century. Weapons that were studied consisted of the pole-axe, spear, long sword, dagger, and hand combat techniques. The project also includes a general study of armor. The final product is an interactive electronic resource (DVD) including information on armor, weapons forms and video demonstrations of the techniques, and a website including highlights from the project