Browsing by Subject "Water -- Analysis"
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Item A comparison of metals in the sediments and water of eleven playas(Texas Tech University, 1995-08) Arefeen, QuamrulNot availableItem Development and analysis of water treatment alternatives for existing water supply in Midland, Texas(Texas Tech University, 1986-05) Mokhtari Hassanabad, Mohammad RezaNot availableItem Experimental and theoretical studies on water(Texas Tech University, 1997-05) Cho, Chul HeeThe properties of water near surfaces or in confined volumes are not well understood. Here, the biologically relevant system chosen for studying the behavior of water near a surface is composed of small water pools encapsulated within sodium bis (2-ethylhexyl)sulfosuccinate (AOT) reverse micelles (RM's), whose surfaces are highly hydrophihc. The time-correlated single-photon counting technique together with an ultrafast laser system was employed to measure the fluorescence lifetimes of the probe molecule ANS within various RM sizes. The resulting decay data were interpreted by using the analytical method and the non-linear least squares fitting technique in order to seek a relationship between diffiision of the probe and a fast nonradiative event. By discovering these trends, information about water properties within different regions of the aqueous core of the RM can be obtained as a function of distance from a surface. The ability of the probe to undergo the fast nonradiative process depends on a reorientational relaxation tune of the water solvent, which may become orders of magnitude slower for water near a surface. Perturbations on the translational velocity autocorrelation function of the probe, as measured by the diffusion fluxes, are very large, extending nearly to the center of the largest RM studied (radius -55 A). On the other hand, perturbations on the orientation relaxation of the solvent, as measured by the probe Hfetimes, were found to extend no more than -10-15 A from the surface of any of the RM's studied. An explanation of the density maximum in water near 4 °C can be described in terms of a dense second-neighbor structure obtained from the bending of hydrogen bonds. The analytical and computational models of water, which provide an explanation of this anomaly, are proposed. In these models, the water-water potential is altered to include more realistic interactions in the second-neighbor shell. Support for this idea is provided here by considering the exactly soluble one-dimensional Takahashi fluid model and then by an NVE molecular dynamics simulation for a realistic water model.Item Selecting a procedure for estimating free water evaporation for the state of Texas(Texas Tech University, 1997-05) Obalapuram, LaxmanEvaporation of water has great bearing on society. Inspite of this, the State of Texas has not kept up with the recommendations of professional societies like the American Society of Civil Engineers and the Natural Resource Conservation Service in adopting scientific and rational procedures to estimate losses of water through evaporation. This study was conducted to decide on the best procedure for estimating evaporation and conclusions were based on statistical analyses performed. Five combinational methods were used to compare the estimates of evaporation against measured evaporation. These are the FAO-24 Penman Method, the Penman- Montieth method, the Kohler-Parmele method, the Kohler-Nordenson-Fox method, and the Borrelli-Sharif method. Three data sets, one from Lubbock, Texas and two from Lake Hefner, Oklahoma were considered. Each of the data sets had daily air temperature, dew point temperature or relative humidity, wind speed, percentage sunshine or incident solar radiation and measured evaporation. Evaporation was measured using either water budget or energy budget. The statistical analyses included average, standard deviation, variance, covariance, standard error of estimate, levels of significance for the means, two sample í-tests, and time series analysis. Results from two of the three data sets show that the Penman- Montieth method gave a better standard error of estimate than all other methods studied, though only marginally.Item The removal of fluorides from public water supplies(Texas Tech University, 1940-08) Litton, James BarronNot availableItem The removal of fluorides from West Texas waters(Texas Tech University, 1937-08) Stewart, Thomas HenryNot available