Spelling suggestions: "subject:"aqueous solutionution"" "subject:"queous solutionution""
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Kinetics of reactions in aqueous solutionsHakin, Andrew William January 1987 (has links)
Rate constants for chemical reactions in various aqueous systems have been measured and analysed. A major part of this thesis discusses the effect of added salts on the reaction kinetics of organic substrates and the effect of added cosolvent on iron(II) complexes in solution. The thesis discusses the properties of aqueous solutions with reference to the prediction of trends in kinetic parameters. Transfer chemical potentials for single ions in 'urea + water' mixtures have been estimated, using solubility data for salts in conjunction with the tetraphenylarsonium tetraphenylboronate assumption. Solvent effects on the initial and transition states for reactions between iron (II) 1,10-phenanthroline and iron(II) glyoxal bis-N methylamine with hydroxide ions are also reported. Solvent effects on initial and transition states for reaction between three iron (II) complexes and hydroxide ions in 'methanol + water' mixtures are reported. Effects of added salt on the neutral hydrolysis of phenyldichloroacetate and the para-methoxy derivative are discussed in terms of solvent cosphere interactions between ions. With regard to computer-based studies osmotic coefficients for ammonium, alkylammonium and azoniaspiroalkane halides have been used with Pitzer's equations and the ideas of Wood et al to produce pairwise Gibbs function cosphere-cosphere interaction parameters. The effects of added salt on rate constants for the alkaline hydrolysis of the sodium salt of bromophenol blue are reported and analysed using Pitzer's equation for the activity coefficients of single ions in aqueous salt solutions. Internal pressures of water and deuterium oxide in the region 273.15? T/K ?373.15 and 0? P/bar ?1000 have been calculated and fitted to an equation based on a Taylor expansion about internal pressure ?i (?,0) at temperature T = 0 and pressure p = n. Calculations are reported which shed light on the controversy concerning the isobaric heat capacities for activation for the solvolysis of alkyl halides in water.
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The structure and dynamics of the hydrated iron (III) ion and related systems in aqueous solutionHerdman, Gawin John January 1989 (has links)
No description available.
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Temperature jump studies of lyotropic liquid crystalsKnight, P. January 1988 (has links)
No description available.
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Characterization of Zinc Oxide Nanotip Prepared by Aqueous Solution Deposition on Sputtered Zinc Oxide Nucleation LayerCheng, Nai-roug 29 July 2010 (has links)
In this study, we prepare the zinc oxide nanotip with aqueous solution deposited on ZnO nucleation layer. The directions of nanotip are formed with different ZnO nucleation layer time. The thermal annealing with N2 ambiance at 300 ¢J for 1 hr increase the UV emission and decrease the defects. We use ZnO nanotip as an anti-reflection layer because of surface roughness and optical interference. ZnO nanotip with rough surface decreases reflection and enhance the transmission, so we use ZnO nanotip as an anti-reflection layer, after growin ZnO nanotip on solar cell the efficiency of solar cell was enhancement.
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Zinc Oxide One-dimensional Nanostructures Prepared with Aqueous SolutionTsai, Yu-Lin 12 August 2008 (has links)
In this study, we prepare the zinc oxide one-dimensional nanostructures with aqueous solution on GaN substrate. The morphologies of nanotip, nanorod and nanotube are formed with different modulation and chemical solutions. The thermal annealing with N2O ambiance at 300 ¢XC for 1 hr increase the UV emission and decrease the defects. The limit of choosing the substrate to grow ZnO nanostructures is lattice mismatch between ZnO and substrate. The buffer layer is sputtered on substrate to remove the limit. The pattern of buffer layer also can be used for selective area growth. Nanotip structure with rough surface shows the obvious lotus effect and nanotube structure with more active site and more surface area shows the better photocatalysis efficiency than nanotip structure.
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Development of anionic clays for water treatmentEngin, Guleda January 2000 (has links)
No description available.
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Structure of gas-liquid interface and hydrophobic interface for urea aqueous solution: a computer simulation studyYu, Meng 15 May 2009 (has links)
Urea aqueous solution is ubiquitously used to denature protein. Regardless of its
extensive use, the mechanism is still unclear and remains an active field of study. There
have been two proposed mechanisms, the direct and indirect. The indirect mechanism,
which attributes the ability of urea of changing water structure, is susceptible since many
research works show that there is little effect of urea on water structure. The current
study provided evidence for the indirect mechanism by demonstrating that the
introduction of urea slightly changes the water structure in the hydrophobic interfacial
areas.
In the current study, the urea aqueous solution systems with either gas-liquid or
hydrophobic interface are studied by MD simulations, and the structures of water near
the interfacial areas are analyzed in terms of density, orientation and number of
hydrogen bonds. For each kind of interface, systems with four different urea
concentrations are included, ranging from 0M to 8M. The results show slight change of
water structure by the urea solute on the hydrophobic interface in terms of the
orientation and number of hydrogen bonds per water molecule.
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Form of Aluminum(III) in Dilute Aqueous SolutionTurner, Laurie J. 04 1900 (has links)
<p> Using a potentiometric method on 10^-4M and 10^-5M Al(NO3)3 solutions at constant ionic strength (0.1 M KNO3) and temperature (25°C), titration curves were defined and examined with respect to three variables (total aluminum concentration, pH range, and time) in order to assess the reversibility of the aqueous system.</p> <p> Increasing pH titration interval decreased reversibility while increasing time interval led to a slight increase in reversibility. Decreasing the total aluminum concentration also slightly improved reversibility. Overall, the reversibility of the system was observed to be poor.</p> <p> Computer models were compared to experimental titration data in order to derive the speciation schemes which best fit the data. Polynuclear hydrolysis schemes fit the data best for the concentration levels as follows: Al^3+, Al(OH)4^-, and Al6(OH)15^3+ for 10^-5M Alt. Al^3+, Al(OH)4^-, and Al8(OH)20^4+ and/or Al13(OH)32^7+ for 10^-4M Alt. / Thesis / Master of Science (MSc)
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Studies on Nucleation from Aqueous SolutionVelazquez, Julio 05 1900 (has links)
<p> The major part of the present work dealt with adapting the
droplet technique to the study of nucleation from solution of some
analytically important metal chelates. Precipitation from homogenous solution was introduced as the means of gradually increasing the supersaturation in the droplets. This new method of producing supersaturation enabled the extention of the droplet technique to
nucleation studies of sparingly soluble substances. </p> <p> In addition, a second novel way of achieving supersaturation
in the droplets was devised. In contrast to the first method, which
increased the amount of solute at constant droplet volume, the second
method maintained the amount of solute constant, while gradually
reducing the volume of the droplet. This permitted studies on
nucleation from solution of soluble substances to be carried out
isothermally. </p> <p> The two techniques mentioned above were applied successfully
to the study of nucleation from solution of four analytically important
metal chelates and to several inorganic salts, respectively. </p> / Thesis / Doctor of Philosophy (PhD)
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Characterization of ZnO Nanorods Grown on GaN Using Aqueous Solution MethodQuang, Hong Le, Chua, Soo-Jin, Loh, Kian Ping, Chen, Zhen, Thompson, Carl V., Fitzgerald, Eugene A. 01 1900 (has links)
Uniformly distributed ZnO nanorods with diameter 70-100 nm and 1-2μm long have been successfully grown at low temperatures on GaN by using the inexpensive aqueous solution method. The formation of the ZnO nanorods and the growth parameters are controlled by reactant concentration, temperature and pH. No catalyst is required. The XRD studies show that the ZnO nanorods are single crystals and that they grow along the c axis of the crystal plane. The room temperature photoluminescence measurements have shown ultraviolet peaks at 388nm with high intensity, which are comparable to those found in high quality ZnO films. The mechanism of the nanorod growth in the aqueous solution is proposed. The dependence of the ZnO nanorods on the growth parameters was also investigated. While changing the growth temperature from 60°C to 150°C, the morphology of the ZnO nanorods changed from sharp tip (needle shape) to flat tip (rod shape). These kinds of structure are useful in laser and field emission application. / Singapore-MIT Alliance (SMA)
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