5,165 research outputs found
PROJECTED USE OF GROUNDWATER FOR IRRIGATION IN THE TEXAS HIGH PLAINS
Projections of groundwater irrigation under alternative price conditions are computed for representative resource situations in the Texas High Plains. The rate of groundwater depletion and pumping costs are related to the level of irrigation pumpage over the period 1976-2026. The projected economic life of irrigation in this region is responsive to changing economic conditions; in particular, the rate of increase in energy prices for pumping.Resource /Energy Economics and Policy,
Single crystalline BaTiO_3 thin films synthesized using ion implantation induced layer transfer
Layer transfer of BaTiO3 thin films onto silicon-based substrates has been investigated. Hydrogen and helium ions were co-implanted to facilitate ion-implantation-induced layer transfer of films from BaTiO3 single crystals. From thermodynamic equilibrium calculations, we suggest that the dominant species during cavity nucleation and growth are H2, H+, H2O, Ba2+ and Ba–OH, and that the addition of hydrogen to the Ba–Ti–O system can effectively suppress volatile oxide formation during layer transfer and subsequent annealing. After ion implantation, BaTiO3 layers contain microstructural defects and hydrogen precipitates in the lattice, but after layer transfer, the single crystal is found to be stoichiometric. Using direct wafer bonding and layer splitting, single crystal BaTiO3 thin films were transferred onto amorphous Si3N4 and Pt substrates. Micro-Raman spectroscopy indicated that the density of defects generated by ion implantation in BaTiO3 can be significantly reduced during post-transfer annealing, returning the transferred layer to its single crystal state. Characterization using piezoresponse force microscopy shows that the layer transferred thin films are ferroelectric, with domain structures and piezoresponse characteristics similar to that of bulk crystals
An Economic Assessment of the Myanmar Rice Sector: Current Developments and Prospects
In this study, the Myanmar rice economy is described in the context of the current political situation and state of national economic development. The forces that are changing rice production and exports are identified; however, the rate of development involves a complex integration of government intervention and politics, as well as availability of resources. Probable scenarios for rice production and export are projected based on recent growth trends and expected infrastructure development. The Arkansas Global Rice Model is used to integrate the Myanmar rice sector with the global rice market in developing projections
Oral History Interview: Dr. Kenneth Young
This interview is one of a series conducted concerning the Kanawha County textbook controversy. The subject of this interview is the Kanawha County textbook controversy, where numerous people protested materials taught in school that they believed immoral, resulting in some violence. Mr. Young was an educator and gives biographical information about himself, describes the textbook selection process, Alice Moore, attempts at arbitration, and parents\u27 role in the school system.https://mds.marshall.edu/oral_history/1239/thumbnail.jp
Physical Studies of Dental Pit and Fissure Sealants
The application of sealants to pits and fissures on occlusal surfaces of teeth as a caries preventive measure has been evaluated in numerous clinical studies. However, the duration of sealant cover and the caries reductions found in these different trials were extremely variable, even where the same materials, and ostensibly the same techniques, had been used. The primary objective of this study was to investigate physical factors involved in applying sealants and to devise changes in materials and application procedures to ensure long term sealant retention and caries reduction. A second objective was to explain the very poor retention found by Stephen, Sutherland and Trainer (1976) for the TP2206 (Alphaseal) fissure sealant system. The effects of various clinical factors, including moisture contamination and surface treatments, on the adhesion between sealant and enamel were assessed using a new tensile testing technique. These tests also indicated the importance of applying sufficient u. v. radiation to set the resins. A subsequent investigation of the output and distribution of radiation from u.v. sources supplied for clinical use, showed a wide range in performance for different units of the same type. In particular, one of the sources used by Stephen et al. (1976) had a very low output. Studies with microhardness measurements showed that Nuva-seal set more rapidly and to a greater final hardness when higher u.v. intensities were used. Alphaseal set more slowly than Nuva-seal, and did not set readily in depth. U.V. absorption measurements indicated that the transmission through Nuva-seal was sufficient to allow setting to the depths normally expected of fissure sealants. Alphaseal showed much stronger absorption, which was partly due to a fluorescent dye incorporated to aid long term sealant detection, and partly due to the high concentration of catalyst used (5% w/w). The setting behaviours of three u.v. activated sealants (Nuva-seal, Alphaseal and Nuva-cote) were compared using a new method, which relied on the passage of acoustic vibrations to determine the set. The nature of the dependence of the rate of set on the u.v. intensity was similar for all three materials. However at any given intensity Nuva-seal set faster than Nuva-cote and Alphaseal by factors of about 4 and 13, respectively. The slow setting of Alphaseal was largely due to the strong absorption of the u. v. radiation in the surface layers. Removing the fluorescent dye and reducing the catalyst concentration to 1% w/w, resulted in an increase in the rate of set of Alphaseal by a factor of
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