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1
Chun, John Hwan. "Modeling of BWR water chemistry." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13660.
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Dudd, Lucinda M. "Organic chemistry in high-temperature water." Thesis, Nottingham Trent University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403413.
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Grover, David J. (David Joseph). "Modeling water chemistry and electrochemical corrosion potential in boiling water reactors." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/39772.
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Gawenis, James Allen. "Aspects of the environmental chemistry of technetium /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3012968.
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Young, Toby Edward. "Water-only chemical analysis methodologies : investigations of water liquid chromatography, subcritical water extracton, and dynamic surface tension detection /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/8528.
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Mahmood, Hosam Rifaat. "Groundwater chemistry and water table variations in Bahrain." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/11707.
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An evaluation has been carried out of the groundwater system in Bahrain. It has involved the collection of water samples from all the water bearing formations to study the quality of the groundwater. Each water sample was tested physically, chemically, and bacteriologically. Additionally, the five day biochemical oxygen demand test and hydrogen sulphide were detected. The period of the actual sampling and testing extended from mid-1990 to the beginning of 1992. The results obtained have been compared to the results of an earlier study conducted between 1978 and 1979. The investigation has also involved a statistical analysis of the variations in the sub-surface water table level in each hydrogeologic formation. The piezometric levels have been collected from monitoring boreholes/ standpipes. The levels obtained extended from the beginning of 1980 when the earliest recording started up to the end of 1991. Bahrain abstracts its fresh water from five aquifers which in descending order are the Sanad, the Alat, the Khobar, the Rus, and the Umm-Er-Radhuma Aquifers. The quality of the groundwater appears to be deteriorating. The excessive groundwater abstraction has caused the encroachment of the sea into all the sub-surface waters. As the waters become saline, they are expected to become unsuitable for human consumption and for irrigation. The deeper aquifers are believed to consist of high values of the hydrogen sulphide because the deeper geological formations contain oil rich in sulphur. land spring water is expected not to be safe bacteriologically because it is exposed to the atmosphere unlike the other boreholes in the various aquifers.The water table levels have been changing in each aquifer. The groundwater levels in the Sanad Aquifer, which is the shallowest geological formation, are expected to rise in the future in areas where the natural drainage is obstructed. This is related to the sea coast reclamation area. The rise is expected to reduce inland depending on the application of surface irrigation as well as the possible leakages from the services systems. About two kilometres south from the original shore, around Buddayya Road, the Sanad Aquifer's water table has been shown to be falling. This fall is expected to be due to overpumping from the groundwater system. Apart from the Sanad Aquifer, the piezometric levels of the underlying aquifers are expected to fall with time. Once again the fall is due to excessive groundwater abstraction. The study concludes by re-presenting the causes for the water table rise in the near-surface Sanad Aquifer and discusses the possible geotechnical consequences. It further produces some possible solutions to control the rise of the water table level.
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Ghasdian, Negar. "ABC terpolymers : micelles, polymersomes and stabilisation of water in water emulsions." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8621.
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Polymersomes are vesicles formed from block copolymers. Their large internal volumes and thick walls make them very attractive for the encapsulation of different species. However, a major issue which prevents the use of polymersomes in most of the applications is that the encapsulation efficiency of payload molecules using current encapsulation methods is too low. This problem is thought to be related to the formation mechanism of polymersomes through self-assembly of the constituent block copolymer molecules. This project is concern with employing a fundamentally different strategy for polymersomes formation and encapsulation based on coupling the separation properties of aqueous two phase systems (ATPSs), which are able to provide w/w emulsions, with templated self-assembly of polymersomes. This novel method provides high encapsulation efficiencies of payload species which is effective, scalable and biocompatible. This work started by design and synthesis of a series of amphiphilic ABC terpolymers consisting of hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate] (PEGMA), hydrophobic poly(n-butyl methacrylate) (BuMA) and hydrophilic poly[2-(dimethylamino) ethyl methacrylate] (DMAEMA) blocks of general structure Px-By-Dz and varied compositional parameters using group transfer polymerisation. The synthesised terpolymers were well-characterised and their ability to self-assemble into polymer structures in aqueous solution was assessed. In addition, we show how these terpolymers can be used as effective stabilisers to stabilise ATPS consisting of dextran and poly(ethylene glycol) in order to form stable water-in-water emulsion or templated polymersomes-like structures, based on the affinity of each block towards the ATPS. The influence of terpolymers compositional parameters on the stability of w/w emulsions or templated polymersome-like structures was investigated. In favourable cases, the emulsion drop (or templated polymersome) sizes were a few μm and were stable for periods in excess of 8 months. The emulsions can be inverted from dextran-in-PEG to PEG-in-dextran by increasing the volume fraction of dextran-rich aqueous phase. We demonstrate that both high and low molecular weight fluorescent solutes “self-load” into either the dextran- or PEG-rich regions and that solute can mass transfer across the water-water interface based on its affinity towards each phase. This work was further extended using modified silica nanoparticles (hydrophobised or PEGylated) for stabilisation of dextran-PEG ATPS. We show how the hydrophobicity and PEGphilicity of such particles can lead to relative stabilisation of dextran-PEG ATPS and formation of particle-stabilised w/w emulsions.
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Wong, Wing-sze. "Water chemistry in the Kam Tin basin, natural and authropogenic influences." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38605843.
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Gutkowski, Sarah. "Water-in-oil and oil-in-water emulsions stabilized by octenylsuccinic anhydride modified starch and adsorption of modified starch at emulsified oil/water interfaces." Thesis, Kansas State University, 2016. http://hdl.handle.net/2097/32842.
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Master of ScienceDepartment of Grain Science and Industry
Yong Cheng Shi
Emulsions are utilized to help control phase separation and are found in many products ranging from food to pharmaceuticals. Because of the hydrophobic properties of its functional group, octenylsuccinic anhydride (OSA) modified starch is commonly used in oil in water (o/w) emulsions. The first objective of this study was to investigate if OSA modified starch could be used in water in oil (w/o) emulsions. Experiments were designed to determine the effects of concentrations of OS starch, mineral oil and water on the stability of emulsions. High shear homogenizers and a microfluidizer were used to create stable o/w and w/o emulsions. The stability of the emulsions was examined by optical microscopy, gravitational separation, and electrical conductivity. The microfluidized samples always had a longer stability (days), no gravitational separation and did not exceed three microns, compared to the unmicrofluidized (o/w and w/o) samples. Stable (over 100 days of stability) o/w emulsions could be made without a microfluidizer if the emulsion was made of 2, 60, 38% (w/w) oil, water, starch, respectively. Stable o/w emulsions prepared with a microfluidizer were stable for over 100 days. The o/w emulsion prepared by 8, 66, 26% oil, water, and starch, respectively, was stable for over 600 days. The most stable w/o unmicrofluidized sample was made of 52, 22, 26% oil, water, starch, respectively, with a stability of 240 days. For the w/o emulsions from the microfluidizer, the most stable emulsion was made of 52, 34, 14% oil, water, starch, respectively, with a stability of 250 days. The most stable emulsion that could flow (under the 30,000 cP) was 56, 38, 6% oil, water, starch, respectively, with a stability of 150 days. The statistical mixture experiments models successfully predicted the stability for other ratios of oil, water, and starch for o/w and w/o emulsions. The second objective of the study was to determine the concentration of modified OS starch adsorbed to the mineral oil and the water phases for oil-in-water (o/w) emulsions. The percentage of the starch adsorbed at the mineral oil phase was determined and compared when different ratios of starch to oil and water were used. When the ratio of oil:starch was decreased, the emulsion particle size decreased. As the starch content increased, the percent starch adsorbed onto oil based on total oil increased. The adsorption yield and the level of starch in the emulsion did not show a trend. The surface load ranged from 1.6 to 6.98 mg/m². The sample with the highest concentration of starch (26 g/ml) had the highest surface load (6.98 mg/m²) and samples with low concentrations of starch (0.84 and 1.68 g/ml) had the second and third highest surface loads (6.82 and 4.70 mg/m², respectively). The ratio of oil:starch was increased to determine the emulsifying capacity. A high emulsifying capacity was achieved. Samples with an oil:starch ratio of 3:1 were stable for over 80 days while other samples with oil:starch ratios of 5:1 and 6:1 could be stable for one week.
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Karlsson, Lovisa. "Water Courses in Kvarntorp : An Evaluation of Water Chemistry from Monitoring Data 1994-2012." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-36474.
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The Kvarntorp area, some 200 km SW of Stockholm, Sweden, is a former mining site for alum shale. Kvarntorpshögen is a refuse dump from the hydrocarbon extraction during 1940-1965. The area is also dotted by abandoned quarries, which most are water filled today. The area is divided into two watersheds; the central and the eastern. Frommestabäcken is the main watercourse flowing out of the central watershed while Frogestabäcken is the corresponding watercourse in the eastern watershed. These two watercourses have been sampled annually since 1994 by consulting companies for the municipality of Kumla. The sampling sites at Ulftorpsbäcken (main inlet to the central watershed) and at the outlet from Serpentindammssystemet (the water treatment system in the central watershed) was added to the sampling program in 1997 and 1996 respectively. Other consulting companies have sampled the groundwater around Kvarntorpshögen (in 2004) and the water in the lake Norrtorpssjön (in 2004), which is an old water filled quarry. The lake Norrtorpssjön has also been sampled as part of a project performed by Örebro University. This thesis is a compilation and evaluation of all this data but the main part will be given focused on seasonal variations. Samples have been analysed with regard to the metals Na, K, Ca, Mg, Fe, Al, Li, B, As, Cu, Ni, Zn, Co, Cr, Cd, Pb, Mo, Sr and U. Other analysed parameters were tot-N, tot-P, bicarbonate (alkalinity), sulphate, chloride and the parameters pH, electrical conductivity and COD(Mn). Samples of bottom fauna have also been collected in Frommestabäcken. Concentration of most metals increased in the surface water while passing the Kvarntorp area. High metal concentrations were found for example in some of the groundwater samples. Such high concentrations were not observed in the samples from Frommestabäcken or Frogestabäcken, indicating for example dilution of metals or immobilisation through precipitation or adsorption. Seasonal effects on the dissolution and precipitation/adsorption of compounds were observed at all annually sampled watercourses. One of these effects was the spring- and autumn circulation of the lake Norrtorpssjön. The lake forms a thermocline during summer which causes higher concentrations of metals beneath the thermocline. During circulation these concentrations mixes throughout the depth profile which affects the amount of elements that is transported from the lake via Frogestabäcken. During winter the highest concentrations of metals are expected near the surface of the lake since the surface is colder than the rest of the water mass.
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Foulger, Timothy R. "Water chemistry variations below regulating reservoirs in Great Britain." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/28049.
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The downstream influence of storage reservoirs upon river water chemistry is an area largely devoid of literature. Yet approximately fifty per cent of such reservoirs in Great Britain significantly regulate flow, both by flood control, and increasingly through irregular but discrete large-volume releases. Natural patterns of stream water chemistry are shown to be disturbed by the effects of Man, through changing land-use and effluent discharge. Moreover, the establishment of a reservoir in the head waters of a major river, can change the water quality regime for a considerable distance below the dam.
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Shavorskiy, Audrey. "chemistry of amino acids at the water-metal interfaces." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529971.
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Cornelissen, Alex. "The chemistry and technology of water cleaning by flocculation." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387927.
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Ajayi, Toluwaleke. "Modeling Discharge and Water Chemistry Using Artificial Neural Network." Ohio University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1620167556121952.
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Kurnia, Drs. "The analytical chemistry of cyanide in acetonitrile-water mixtures." Thesis, Drs Kurnia, (1995) The analytical chemistry of cyanide in acetonitrile-water mixtures. PhD thesis, Murdoch University, 1995. https://researchrepository.murdoch.edu.au/id/eprint/51574/.
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A method for the simultaneous determination of total gold and available cyanide in gold cyanidation solutions has been investigated. Total gold and available cyanide in cyanidation solutions are determined by ion exchange chromatography-HPLC under slightly acidic conditions. Cyanide is determined by measuring the peak height associated with the formation of the nickel-cyanide complex which is formed by adding an excess of nickel(II) to the gold cyanidation solution. The nickel(D)-cyanide complex is not strong enough to dissociate the very strong dicyanoaurate(I). Anion exchange is used for the separation of the cyano complexes of gold(I) and nickel, using a solvent comprising acetonitrile-water and containing citrate as counterion at pH 6.0 with UV-VIS detection at 229 nm. This provides two HPLC peaks, one giving the dicyanoaurate( I) complex and the other giving the concentration of the "available cyanide" as its nickel complex. The method is fast, accurate, sensitive, relatively cheap and can easily be made free from interfering anions commonly found in gold cyanidation solutions.
In order to provide a basis for further development of this procedure in the presence of potentially interfering cations such as zinc(II) and copper(I), the formation constants of the metal-cyanide complexes were determined by potentiometric titrations in five different AN/H2O mixtures at 25°C and I = 1 M (Na)C1O4. Only the formation constants of cyanide complexes of Cd(II), Zn(II) and Cu(I) could be determined at the present study. Other metals of interest including nickel(II) were too strong to be studied by glass electrode potentiometry.
Evidence was obtained for the formation of ternary Mn+/CN-/OH- complexes at high pH. However, only the formation constants of the binary Mn+/CN- complexes could be determined due to the lack of quantitative information for the hydroxo complexes in these solvent mixtures.
The M'7CN equilibria shift strongly in favour of the formation of the higher-order complexes (n=3,4) at high acetonitrile concentrations. These changes are rationalised in terms of the Gibbs energies of transfer of the various species from water to the AN/H2O mixtures.
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Wells, David Alan. "Radon properties, chemistry and occurrence with emphasis on ground water." Master's thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-04272010-020026/.
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Gustafson, Joseph Rhodes. "Quantifying Spatial Variability of Snow Water Equivalent, Snow Chemistry, and Snow Water Isotopes: Application to Snowpack Water Balance." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193330.
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This study quantifies spatial and temporal patterns in snow water equivalent (SWE), chemistry, and water isotopes associated with snowpack shading due to aspect and vegetation in the Valles Caldera National Preserve, New Mexico. Depth, density, stratigraphy, temperature, and snow chemistry, isotope, and biogeochemical nutrient samples were collected and analyzed from five snowpit locations on approximate monthly intervals between January-April 2007. SWE showed little variability between sites in January (~10mm) but differences expanded to 84mm (30%) by max accumulation in open sites and 153mm (45%) between all sites. Sulfate varied by 22% (10.6-13.5 microeq/L), Cl- by 35% (17.4-26.9 microeq/L), and d18O by 17% (-16.3 to -13.5), with SWE exhibiting inverse correlations with d18O (r2=0.96), SO42- (r2=0.75), and Cl- (r2=0.60) at max accumulation. Regression relationships suggest variability in SWE and solutes/water isotopes are primarily driven by sublimation. Mass balance techniques estimate sublimation ranges from 1-16% between topographically- and non-shaded open sites.
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Huntress, David William. "Chemical Dynamics During High Discharge Events at Three Forested Catchments in Eastern Maine, USA." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/HuntressDW2008.pdf.
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Wang, Ying. "Theoretical Studies on Artificial Water Splitting-Water Oxidation and Proton Transfer." Licentiate thesis, KTH, Teoretisk kemi och biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102566.
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The present thesis is concerned with the theoretical studies on artificial water splitting process. As the quick development of research on utilizing of solar energy, which is a green, clean, and renewable energy source, many research groups focus their attention on artificial photo-synthesis systems inspired by the photosystem I and II. The overall reaction in these artificial systems is water splitting to oxygen and hydrogen. Artificial water splitting can generally be divided into two half reactions, catalytic water oxidation and catalytic proton reduction. There is an increasing interest and demand to understand the detailed mechanism of these two key parts. Since DFT (density functional theory) in particular, has proven to be a powerful and popular tool in exploring reaction mechanisms, B3LYP and M06 functionals were employed to provide a theoretical explanation of these two important reactions in this thesis. For water oxidation reaction, many efficient Water Oxidation Catalysts (WOCs) based on Ru, Ir, etc., have been reported over the last several years. The discovery of mononuclear ruthenium WOCs carrying anionic ligands is one of the major breakthroughs recently. WOCs bearing anionic ligands are able to efficiently drive catalytic water oxidation with relatively higher Turnover Numbers (TON) and Turnover Frequencies (TOF). Therefore the influence of anionic ligands gained our attention. We decided to carry out a detailed investigation on this effect, and try to propose a full mechanism of this catalytic water oxidation as well. We found that 1) The anionic ligands exert a promoting influence on the ligand exchange between picoline and water, which facilitates the formation of aqua-Ru complex, 2) The anionic ligands facilitate the complex access to higher oxidation states, which is necessary for the OO bond formation, and 3) The work of OO bond formation is in progress. For the proton reduction reaction, the transport or movement of protons is vital and interesting in many biological and chemical processes, including the hydrogen uptake/production, the reduction of CO2 to formate, and the reduction of O2 to water. It is often related to energy storage and utilization. However, the details of these processes are still ambiguous. In most natural hydrogenase enzymes or synthetic catalysts based on iron or nickel, the incorporation of a pendant amine is a frequently occurring feature. This internal amine base seems to facilitate this proton transfer by acting as a proton relay. Our calculated results showed that the internal base allows for a splitting of one high enthalpy-high entropy barrier into two: one with a high enthalpy-low entropy barrier and the other with a low enthalpy-high entropy barrier, resulting in a low free energy of activation for proton transfer. Our results can serve as a guideline in the development of new catalysts, not only for proton reduction catalysts, but also for any process that involves proton transfer from a metal hydride to an external base, such as C-H activation and functionalization catalysts. A thorough understanding on the mechanism of water splitting can help generate a strategy to enhance the catalytic performance on both water oxidation and proton reduction. We can tune or modify the synthetic complex by accelerating the slow step (rate-determining step) in the overall catalytic cycle, and can construct artificial water splitting systems with improved performance.QC 20120920
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Sayed, Shakeela. "Remediation of water using modified chitosan." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/6361.
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Includes bibliographical references.Water treatment has been an area of increasing concern over the last decade. This interest is due to exponential increase in demand of already limited water sources. Therefore the treatment of wastewater for re-use is a topic of great interest. The treatment applied depends on the source and quality of the water. Common water treatment options include filtration, flocculation, coagulation, lime softening, reverse osmosis and clarification to name a few. In addition, water should also be treated for the presence of harmful micro-organisms which is normally done using chlorine-based disinfection. Water purification filters which purify water by removal of impurities and micro-organisms are in great demand. Therefore the aim of this study was to develop ion exchange polymers and antimicrobial filters using ‘green’ materials.
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Walker, I. M. "The formation and evaluation of water-in-oil-in-water multiple emulsion systems." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371137.
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Rowell, Simon C. "Mechanism and promotion of Sandmeyer chemistry." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387548.
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McCormick, John. "Chemistry of titanium dioxide nanoparticles." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 10.93 Mb., 224 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220706.
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Tuladhar, Aashish. "Structure and Dynamics of Water Next to Mineral Surfaces." Diss., Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/420679.
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ChemistryPh.D.
Vibrational sum frequency generation (vSFG) spectroscopy is a second order non-linear technique that can efficiently and selectively investigate an interface between two media. vSFG spectroscopy has been frequently used to interrogate the mineral/water interface by probing the interfacial O−H stretch, which is an excellent reporter of its hydrogen bonding environment. My work, described in this dissertation, is focused on using steady-state and time-resolved vSFG spectroscopy to understand how (a) the type of mineral, (b) the crystalline faces of the mineral, (c) the surface charge of the mineral, and (d) the ionic strength of the bulk liquid affect the structure and the ultrafast dynamics of the mineral/water interface. The results obtained for alumina/water interface are compared with the more commonly studied silica/water interface. The Al2O3/H2O interface provides an ideal opportunity to study the behavior of water next to a positively charged, neutral, and negatively charged mineral surface since its point of zero charge (PZC) lies near the pH of neutral water (pH 6-8). In contrast, due to its low PZC (~pH 2), silica surface is usually neutral or negatively charged. Additionally, a-alumina is crystalline in structure and can be cut to expose different faces (e.g., 0001, 11 ̅02, 112 ̅0) which has been speculated to uniquely affect the ordering and the hydrogen bonding environment of its adjacent water molecules. Our vSFG spectra of the O-H stretch at the alumina/water interface revealed the presence of highly red-shifted 3000 cm-1 species, which is absent at the silica/water interface. With the help of DFT calculations, we assigned the red-shifted peak to the O-H stretch of strongly hydrogen bonded surface aluminol groups and/or interfacial water molecules that are hydrogen bonded to the mineral surface. The 3000 cm-1 species was present at both the Al2O3(0001) and the Al2O3(112 ̅0) surface, but was more prominent for the latter which resulted in the O-H stretch of the Al2O3(112 ̅0)/H2O interface to appear more red-shifted compared to the Al2O3(0001)/H2O interface. This observation provided us with an experimental evidence that the water next to the Al2O3(112 ̅0) surface is in a stronger hydrogen bonded environment than next to the Al2O3(0001) surface as predicted by Catalano’s X-ray reflectivity measurements. Additionally, IR pump - vSFG probe experiments were used to investigate the ultrafast vibrational dynamics of the O-H stretch at alumina/water interfaces. The vibrational dynamics at the Al2O3(112 ̅0)/H2O interface was observed to be fast (T1 = 100-130 fs) and not affected by the mineral surface charge (controlled by bulk pH) or the ionic strength (up to 0.5 M NaCl). In contrast, for the Al2O3(0001)/H2O interface, the vibrational dynamics was observed to be two times faster for the charged surface (T1 ~ 105 fs) compared to the neutral surface (T1 ~ 220 fs). This result provides further evidence that the water next to the Al2O3(112 ̅0) surface is more ordered and/or strongly hydrogen bonded compared to the water next to the Al2O3(0001) surface. The vibrational dynamics observed at the charged Al2O3(0001)/H2O interface (T1 ~105 fs) is faster than in bulk water and at the charged silica/water interface (T1 = ~200 fs). We speculate that the red-shifted 3000 cm-1 species present at the alumina/water interface plays a major role in the mechanism of vibrational relaxation since the 3000 cm-1 species is present at the alumina/water interface and not at the silica/water interface. The main mechanism of vibrational relaxation of the O-H stretch in bulk water is known to proceed via the Fermi-resonance coupling between the overtone of the water bend and the O-H stretch. The presence of red-shifted O-H species at the alumina/water interface could lead to better coupling between the O-H stretch and the water bend overtone and hence result in faster vibrational relaxation than in bulk water. Alternatively, a new pathway of vibrational relaxation via an ultrafast excited state proton transfer reaction could be operative for the alumina/water interface due to the presence of different types of O-H stretches (arising from aluminol groups and water molecules). Such a mechanism would not be possible at the silica interface due to the significantly lower density of surface bound hydroxyls. We are not able to determine the dominant mechanism for vibrational relaxation at the alumina/water interface with our current experiments and therefore, our future work will involve collaborations with theoretical groups in order to answer this question.
Temple University--Theses
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Wang, Ruifu. "The Solution Behavior of Abundant Metals based Water Oxidation Catalysts." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460301627.
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Brown, Stacy D. "The Formula For Water." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etsu-works/5257.
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Morten, Christopher J. (Christopher John). "Endo-selective epoxide-opening cascades in water." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65271.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Vita. Cataloged from PDF version of thesis.
Includes bibliographical references.
Chapter I. Introduction to the Ladder Polyethers. We introduce the bioactivity of the ladder polyether natural products and provide an overview of the puzzle that is their biogenesis. Cascades of endo-selective epoxide opening inspired by the biosynthetic proposal and promoted by simple neutral water can provide efficient access to these compounds. Chapter II. Water-Promoted Epoxide Opening Accommodates Methyl Substitution. ... Methyl (Me) substitution poses a challenge to the achievement of endo-selective epoxide-opening cascades, as these groups can direct the regioselectivity of epoxide opening. Water as reaction solvent and promoter overcomes such directing effects and enables the incorporation of proximally Me-substituted epoxides into endo-selective cascades. However, Me-substituted epoxides do reduce the overall efficiency of cascades. Chapter III. Kinetics of an Epoxide-Opening Cascade Promoted by Neutral Water. Evidence for a Stepwise Mechanism. ... Detailed investigation of the kinetics of an endo-selective epoxide-opening cascade in water reveals a stepwise mechanism, not a concerted one. While the first step proceeds with poor rate and selectivity, the second cyclization, which is templated by a fused THP diad, proceeds with excellent endo selectivity. Chapter IV. Preliminary Investigation of a Dioxane Template for Endo-Selective Epoxide-Opening Cyclization. ... Use of a 1,3-dioxane as template ring, a methylene acetal engenders endoselective epoxide opening under both acidic and basic conditions. Cyclization in neutral water proceeds with superb endo selectivity. Chapter V. Progress Toward the Synthesis of Gambierol via Endo-Selective Epoxide-Opening Cascades Promoted by Water. ... We report progress toward the biomimetic total synthesis of the ladder polyether gambierol. The FGH ring system has been synthesized in a 20 step longest linear sequence, via an endo-selective epoxide-opening cascade promoted by water. Chapter VI. Conclusion: Potential Implications of the Foregoing Work on the Biosynthesis of the Ladder Polyethers. We summarize lessons learned from in vitro emulation of the hypothesized biosynthesis of the ladder polyethers and speculate on the possibility of ring junction methylation subsequent to the epoxide-opening cascade step.
by Christopher J. Morten.
Ph.D.
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Mokoena, Allistair Frans. "Water dynamics about selected monosaccharides in solution." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13382.
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Includes bibliographical references.The solubility of molecules in water is governed, amongst other things, by the inherent properties of the solute molecules and water molecules. Water molecules are able to simultaneously form hydrogen bonds as donors and acceptors and thus have unique properties as solvent molecules. These properties influence how water interacts with solute molecules. The mechanism of hydrogen bond exchange plays a role in the hydration of solute molecules. A key to understanding some of the biological processes lies in understanding how solutes interact with water. In this thesis, the hydration of monosaccharides has been studied using computational methods. The hydration structure is elucidated by pair distribution functions and spatial distribution functions. Hydrogen bond exchange dynamics were investigated on the basis of the molecular jump mechanism. Evaluation of the hydrogen bond exchange dynamics reveals two possible pathways. The first pathway corresponds to the molecular jump mechanism reported in literature. The second pathway is described. This pathway provides details on the water-hydroxyl interactions taking place around the monosaccharides. It is shown that the presence of a primary alcohol on pyranose based molecules induces a configuration that allows favourable interactions between water molecules and hydroxyl groups on the sugar molecules. A region of high water density is formed between the primary alcohol, ring oxygen and the hydroxyl on the anomeric carbon. This is due to rotations by water molecules from one hydroxyl, to the adjacent hydroxyl on the sugar molecule. It is not only the presence of the primary alcohol that plays a role in the hydration of the monosaccharides. The relative position of the hydroxyl on the anomeric carbon is shown to create a topology conducive of hydroxyl to hydroxyl hydrogen bond exchanges. The hydration of monosaccharides is rationalised by these effects.
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Roger, Barba Isolda. "Investigations into electrochemical water splitting." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/8228/.
Full textAbstract:
The work detailed in this thesis is organized in the following manner: In Chapter 1 we discuss electrochemical and photoelectrochemical catalysts in the context of their application for solar-to-hydrogen devices. During this introduction we will give an overview of the current state of the field, discussing the different kinds of materials that are being investigated before giving a brief description of some actual solar-to-hydrogen devices and finishing with a discussion of the current and future challenges in the field. Chapter 2 is a description of the different techniques used throughout this thesis. Once having set the bases, we shall start with the actual research, which corresponds to Chapters 3 to 5. Chapter 3 and 4 deal with the effect of trace metal impurities in electrochemical water splitting. In Chapter 3 we show that adventitious nickel at trace levels can act as a water oxidation catalyst in mildly basic aqueous solutions at overpotentials comparable to many recently-reported water oxidation catalysts, therefore serving to raise the burden of proof required of new materials in this field. Chapter 4 shows how silver ions leaking from Ag/AgCl reference electrodes in aqueous buffers at low pH can deposit on the working electrode as Ag(0) and catalyze the hydrogen evolution reaction, calling into question the validity of any reports using these electrodes that cannot demonstrate significantly superior activity to the baseline we set in this chapter. In Chapter 5 we describe a direct hydrothermal deposition method to prepare Cobalt-doped MoS2 thin films onto transparent Fluorine-doped SnO2 substrate and demonstrate that the obtained films display good activity for the hydrogen evolution reaction from acid solution.
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Kuo, Yenting. "Photocatalytic water splitting." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/12141.
Full textAbstract:
Doctor of PhilosophyDepartment of Chemistry
Kenneth J. Klabunde
New photocatalystic materials Ti-In oxy(nitride) and nanosized Ru-loaded strontium titanate doped with Rh (Ru/SrTiO3:Rh) have been synthesized. The textural and surface characteristic properties were studied by nitrogen BET analysis, diffuse reflectance UV-vis spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and powder XRD. The photocatalytic properties were enhanced by the binary metal oxides of titanium dioxide and indium oxide. The XRD patterns confirmed the oxygen exchange between two metal oxides during the synthesis. Moreover, the presence of titanium dioxide can help the stabilization of InN during hot NH3(g) treatment. On the other hand, the particle sizes of aerogel prepared Ru/SrTiO3:Rh varied from 12 to 25 nm depended on different Rh doping. A mixture of ethanol and toluene was found to be the best binary solvent for supercritical drying, which yielded a SrTiO3 sample with a surface area of 130 m2 Enhanced photocatalytic hydrogen production under UV-vis light irradiation was achieved by ammonolysis of intimately mixed titanium dioxide and indium oxide at high temperatures. Gas chromatography monitored steadily the formation of hydrogen when sacrificial (methanol or ethanol) were present. XRD patterns confirmed that the photocatalysts maintain crystalline integrity before and after water splitting experiments. Moreover, the presence of InN may be crucial for the increase of hydrogen production activities. /g and an average crystallite size of 6 nm. These Ru/SrTiO3:Rh photocatalysts have been studied for photocatalytic hydrogen production under visible light. The band gap of the bulk SrTiO3 (3.2 eV) does not allow response to visible light. However, after doping with rhodium and loaded with ruthenium, the modified strontium titanates can utilize light above 400 nm due to the formation of valence band or electron donor levels inside of the band gap. Moreover, the surface areas of these photocatalysts are much larger than conventional solid-state synthesized samples (1-2 m 2/g), which yielded more Ru loading and reaction sites. The areogel and hydrothermal synthesized samples required basic (alkaline) conditions for hydrogen generation facilitation compared with acidic conditions for conventional solid-state samples.
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Zhang, Yan. "Relative Effects of Water Chemistry on Aspects of Iron Corrosion." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/35501.
Full textAbstract:
The net present replacement value of all publicly and privately owned potable water
pipes in the U.S. is on the order of $2.4 trillion dollars, and costs associated with
deteriorating iron pipes is billions of dollars per year. Problems arising from iron
corrosion include reduced lifetime of the material, scale buildup and energy loss, nonuniform
corrosion and leaks, catastrophic failure, "red water," disinfectant loss and
bacterial re-growth. Iron corrosion is a very complicated process and is affected by many
factors. This research focused on the effect of disinfectant type, sulfate/chloride ratios,
nitrate concentration, and magnesium hardness on iron corrosion. For the waters tested,
chlorine better controlled red water and microbial activity in the bulk solution than
chloramine. Changes in the sulfate/chloride ratio did not have a large effect on iron
corrosion. High levels of nitrate increased the rate of chlorine decay as a result of free
ammonia formation, and also increased the release of iron. Increased magnesium and
zinc decreased the red water caused by high silicate.
Microbiological activity is important in iron corrosion, and control of re-growth in
water distribution systems is a major challenge for water utilities. A separate study
examined the inter-relationship between iron corrosion and bacterial re-growth, with a
special focus on the potential of iron pipe to serve as a source of phosphorus. Under
some circumstances corroding iron and steel may serve as a source for all macronutrients
necessary for bacterial re-growth including fixed carbon, fixed nitrogen and phosphorus.
Conceptual models and experimental data illustrate that levels of phosphorus released
from corroding iron are significant relative to that necessary to sustain high levels of
biofilm bacteria. Consequently, it may be more difficult to limit re-growth on iron
surfaces by limiting phosphorus in the bulk water.Master of Science
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Doremus, Llyn, and David Kreamer. "Groundwater Movement and Water Chemistry at Bryce Canyon National Park." Arizona-Nevada Academy of Science, 2000. http://hdl.handle.net/10150/296565.
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Withers, Anthony Charles. "Water in the mantle." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390105.
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Barker, Jason Alan. "Investigations of Liposome/Water Partitioning Using Electrokinetic Chromatography." NCSU, 2005. http://www.lib.ncsu.edu/theses/available/etd-01072005-041518/.
Full textAbstract:
In this two-part investigation, Linear Solvation Energy Relationship (LSER) models were applied to liposome/water partitioning data determined by liposome electrokinetic chromatography (LEKC). In the first part of the study, LEKC retention factors were determined for a set of 71 solutes including 50 neutral aromatic solutes and 21 neutral drugs using the liposome phases mM DPPG20DPPC80, 15 mM DPPG20DPPC80/3 mM cholesterol, and 15 mM DPPG20DPPC80/6 mM cholesterol. These retention factors were used to determine linear solvation energy relationships (LSER) models for each of the three lipid phases for the set of 50 neutral aromatic solutes and the entire set of 71 solutes. The predictive ability of the LSER model was tested by using the model generated for the set of 50 neutral aromatic solutes to predict retention factors for the 21 neutral drugs. The descriptive ability of the LSER model was tested and used to examine the interactions that control liposome/water partitioning for the set of 50 neutral aromatic solutes and the set of 71 solutes including 21 neutral drugs. In the second part of the study, wo liposome electrokinetic chromatography (LEKC) lipid phases were introduced that approximate the lipid composition of the cell membrane of monkey intestinal epithelial cells. 15 mM PI10DPPS10DPPC30DPPE30SPM20/9.75 mM cholesterol most nearly approximates the lipid composition of the cell membrane of monkey intestinal epithelial cells. 15 mM DPPG20DPPC80/9.75 mM cholesterol replaces the specific lipids contained in the monkey intestinal epithelial cell membranes with the zwitterioninc lipid DPPC and DPPG. The retention factors determined for a set of 50 neutral aromatic solutes using these two LEKC phases are highly correlated (r2=0.99), with a slope near unity (m=0.91) and an intercept near zero (b=0.05). The normalized LSER system coefficients for these lipid phases are also very similar. The LSER system coefficients determined for 15 mM PI10DPPS10DPPC30DPPE30SPM20/9.75 mM cholesterol and 15 mM DPPG20DPPC80/9.75 mM cholesterol were compared with an LSER model generated by Abraham, et al. for human intestinal absorption.
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Eaves, Joel David 1976. "Vibrational dynamics in water from the molecule's perspective." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30206.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.
Includes bibliographical references.
Liquid water is a fascinating substance, ubiquitous in chemistry, physics, and biology. Its remarkable physical and chemical properties stem from the intricate network of hydrogen bonds that connect molecular participants. The structures and energetics of the network can explain the physical properties of the substance on macroscopic length scales, but the events that initiate many chemical reactions in water occur on the time scales of [similar to] 0.1 - 1 picosecond. The experimental challenges of measuring specific molecular motions on this time scale are formidable. The absorption frequency of the OH stretch of HOD in liquid D₂0 is sensitive to the hydrogen bonding and molecular environment of the liquid. Ultrafast IR experiments endeavor to measure fluctuations in the hydrogen bond network by measuring spectral fluctuations on femtosecond time scales, but the data do not easily lend themselves to a direct microscopic interpretation. Computer simulations of empirical models, however, offer explicit microscopic detail but must be adapted to include a quantum mechanical vibration. I have developed methods in computer simulation to relate spectral fluctuations of the OH stretch in liquid D₂0 to explicit microscopic information. The experiments also inform the simulation by providing important quantitative data about the fidelity and accuracy of a chosen molecular model, and help build a qualitative picture of hydrogen bonding in water. Our atomistic model reveals that ultrafast experiments of HOD in liquid D₂0 measure transient fluctuations of the liquid's electric field. On the fastest time scales, localized fluctuations drive dephasing, while on longer time scales larger scale molecular reorganization destroys vibrational coherence.
(cont.) Because electric fields drive vibrational dephasing, the frequency of the OH stretch is particularly sensitive to the microscopic details of the molecular potential. With collaborators, I have examined the accuracy of emerging fluctuating charge models for water and the role that molecular polarizability plays in the vibrational spectroscopy. In liquid water at ambient conditions, roughly 90 % of the hydrogen bonds are intact. I have examined the fates and the fundamental chemical nature of the remaining 10 % of the "broken" hydrogen bonds. We consider two reaction mechanisms that describe how hydrogen bonds change partners. In the first scenario, broken hydrogen bonds exist in stable chemical equilibrium with intact hydrogen bonds. In an alternate scenario, the broken hydrogen bond is not a meta-stable chemical state but instead a species that molecules visit during natural equilibrium fluctuations or when trading hydrogen bonding partners. I show how the methods of condensed phase reaction dynamics can be directly applied to vibrational spectroscopy of reactive systems and how experimental 2D IR spectra can distinguish between the two mechanistic scenarios. Our data support the notion that broken hydrogen bonds are an intrinsically unstable species in water and return to form hydrogen bonds on the time scale of intermolecular motions.
by Joel David Eaves.
Ph.D.
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Shrestha, Sweta. "Photochemical Water Oxidation by Zeolite-supported Manganese Oxides." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408983765.
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Baines, Fiona Louise. "Water-soluble hydrophilic-hydrophobic block copolymers." Thesis, University of Sussex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283139.
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Li, Muxiu. "Synthesis of functional water-soluble polymers." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/60357/.
Full textAbstract:
The objective of this work was to synthesise water-soluble polymers bearing desirable functionality, particularly to improve water-solubility of phthalocyanines by incorporation of hydrophilic polymers for personal oral care applications. Prior to preparation of water-soluble polymers containing phthalocyanine, the second chapter described the synthesis of ferrocenyl initiator for polymerisation of tert-butyl acrylate by SET-LRP, followed by acidolysis of tert-butyl group yielding poly(acrylic acid) containing ferrocenyl end group. The resulting polymer could be used as the scale inhibitor for a potential oil drilling application, and further detected by cyclic voltammetry due to the presence of the ferrocene end group. The majority of the thesis is focussed on an investigation of novel approaches for covalently attachment of water-soluble polymers to (copper or zinc) phthalocyanines. The initial PEGylated CuPc complexes were obtained via DCC/EDC coupling reactions, and the resulting blue powder showed excellent solubility in water; however, it revealed a broad molecular weight distribution due to the presence of mono-, di-, and tri- substitutions of PEG chains as confirmed by GPC analysis. PEGylation of phthalocyanines were further improved via a combination of Mitsunobu reaction and CuAAC “click” reaction. In this approach, the substituted macrocycles were prepared from 4,5-bis-(4-hydroxyphenoxy)phthalonitrile as a precursor. The final PEGylated CuPcs or metal-free Pcs with different PEG chain lengths were prepared by two different routes. The incorporation of the (Cu)Pc core with the polymer chain was confirmed and distinguished by THF-GPC equipped with a PDA detector, and also showed an increase in hydrodynamic volume with increasing the PEG chain length with a narrow dispersity remained. PDMAEMA, as a dual responsive polymer was also introduced to ZnPc using a core-first approach by a combination of ATRP and CuAAC reaction with sharing the same CuBr/PMDETA catalyst, yielding the star-shaped water-soluble polymer. The polymer solution represented tuneable LCSTs in range between 83 and 33 oC with increasing the pH of the buffer solution from 7 to 10. The polymer was further transformed into highly polyelectrolyte stars with ZnPc core by quaternization of the pendant amino groups with either methyl iodide or 1,3-propanesultone. The resulting zwitterionic star after quaternized with propanesultone, ZnPc-PMEDSAH, exhibited a UCST value 17 oC, compared with the quaternized salt, ZnPc-PMETAI with no obvious phase transition observed. In addition, their optical properties and aggregation behaviour in water were investigated by UV-Vis spectroscopy. The final study involved the synthesis of water-soluble zinc phthalocyanines conjugated to poly(galactose) by an arm-first approach. The well-defined protected galactose oligomer arm was synthesised by SET-LRP with a desirable ω-chain end as confirmed by MALDI-ToF MS analysis which were ready for postfunctionalisation. Following a click reaction and deprotection of the acetal groups, the isolated green powder achieved good water-solubility and emitted a sharp fluorescent band at approximate 695 nm via excitation at 610 nm in DMF. The GPC analysis also showed that a narrow molecular weight distribution remained after deprotection and confirmed the presence of ZnPc core by the PDA detector.
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Saha, Shikha. "Stationary phases for superheated water chromatography." Thesis, Loughborough University, 2002. https://dspace.lboro.ac.uk/2134/35589.
Full textAbstract:
This project focused on the comparison of conventional liquid chromatography and superheated water chromatography. It examined the differences in efficiency and retention of a range of different stationary phases. Alkyl aryl ketones and eight aromatic compounds were separated on PBD-zirconia, Xterra™ RP 18, Luna™ C18(2) and Oasis HLB™ columns using conventional LC and superheated water chromatography system. The retention indices were determined in the different eluents. On changing the organic component of the eluent from methanol to acetonitrile to superheated water considerable improvements were found in the peak shapes and column efficiencies on the PBD-zirconia and Oasis HLB™ columns.
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Bymers, Leah. "The effects of changes in flow on the ecological condition of two Arizona streams analysis of trends in water chemistry and structure of biological assemblages /." Thesis, The University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0076_sip1_w.pdf&type=application/pdf.
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Beck, Corey Andreu. "Theoretical Studies of Solid and Liquid Water Systems." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337969878.
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Benning, B. K. "Novel high water content hydrogels." Thesis, Aston University, 2000. http://publications.aston.ac.uk/9809/.
Full textAbstract:
The addition of N-isopropyl acrylamide to an acrylamide-based composition that had previously been designed to become a contact lens, produced materials that showed smart effects in that the water content showed dependence on the temperature of the hydrating solution. Such thermo-responsive materials have potential uses in drug delivery, ultrafiltration and cell culture surfaces. Proteoglycans in nature have an important role to play in structural support where a highly hydrophilic structure maintains lubricious surfaces. Certain functional groups that impart this hydrophilicity are present in certain sulphonate monomers, Bis(3-sulphopropyl ester) itaconate, dipotassium salt (SPI), 3-Sulphopropyl ester acrylate, potassium salt (SPA) and Sodium 2-(acrylamido)-2-methyl propane sulphonate (NaAMPS). These monomers were incorporated into a HEMA-based copolymer that had been designed initially as a contact lens and the resulting effects examined. Highly hydrophilic materials resulted that showed reduced protein deposition over the neutral core material. It is postulated that a sulphonate group would have a larger number of hydration shells around it than for example methacrylic acid, leading to more dynamic exchange and so reducing the adsorption of biological solutes. A cationic monomer was added to bring back the net anionic nature of the sulphonate hydrogels and the effects studied. Ionic interactions were found to cause a reduction in the water content of the resulting materials as the mobility of the network decreased, leading to stiffer but less extensible materials. The presence of a net dominant charge, whether negative or positive, appeared to act to reduce protein deposition, but increasing equivalence in the amount of both charges served to present a more 'neutral' surface and deposition subsequently increased. The grafting of hydrophilic hydrogel layers onto silicone elastomer was attempted and the results evaluated using dynamic contact angle measurements. Following plasma oxidation to reduce the surface energy barrier to aqueous grafting chemistry, it was found that the wettability of the modified elastomers could be significantly enhanced by such treatment. The SPA-grafted material in particular hinted at an osmotic drive for rehydration that may be exploited in biomaterials.
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Fecko, Christopher J. 1975. "Spectroscopic investigations of hydrogen bond dynamics in liquid water." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/16652.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.MIT Institute Archives copy: pages 215 to 304 bound in reverse order.
Includes bibliographical references.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Many of the remarkable physical and chemical properties of liquid water are due to the strong influence hydrogen bonds have on its microscopic dynamics. However, because of the fast timescales involved, there are relatively few experimental techniques capable of directly probing rearrangements of water's hydrogen bonded network. In this thesis, I investigate ultrafast intermolecular dynamics of water with time-resolved Raman and time-resolved infrared spectroscopies. These two sets of measurements provide a complimentary view of the collective and local behavior of molecular motions. Using a novel Raman technique, spatially masked optical Kerr effect spectroscopy, I first measured interaction-induced fluctuations in the isotropic many-body polarizability of water and several other liquids. In contrast to the behavior of simple liquids, the isotropic response of water is exceedingly fast and distinct from the well-known anisotropic response. I then designed and built an optical parametric amplifier that produces sub-50 fs pulses of mid-IR light to investigate the intermolecular dynamics of water through their effect on the OH oscillator of HOD in D20. By analyzing the results of three-pulse vibrational echo and polarization- selective pump-probe measurements with a comprehensive theory to describe vibrational dynamics, I extracted the timescales for vibrational relaxation, dephasing and molecular reorientations.
(cont.) At short times, vibrational dephasing reflects an underdamped 180 fs hydrogen bond oscillation, but the long time behavior indicates collective structural reorganization of the hydrogen bond network a 1.4 ps timescale. The anisotropy decays on timescales of 50 fs and 3 ps, which are attributed to librations and rotational diffusion, respectively. Lastly, I used two-dimensional infrared spectroscopy to investigate the frequency dependence of the dynamics. Preliminary results reflect a distribution of timescales for both local motion and collective reorganization.
by Christopher J. Fecko.
Ph.D.
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Seymour, Lisa. "A computer model of water-in-oil emulsion coagulation." Doctoral thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/17966.
Full textAbstract:
Include bibliographical references.In this thesis, a stochastic computer model of water-in-oil emulsion coagulation, a two stage process of aggregation and coalescence, is presented. The theoretical basis of the model, including equations for the van der Waals, electrostatic and steric energy barriers between dissimilar droplets, is described. Many of these equations have been derived by the author. A chemical speciation study of the aqueous phase typically found in emulsion explosives is presented. A potentiometric investigation of the protonation equilibria of propionate, succinate and mono-methyl succinate in tetraethyl ammonium bromide, ammonium nitrate, sodium nitrate, potassium nitrate and calcium nitrate at 25°C and 3 mol/dm³ ionic strength was performed. Nuclear Magnetic Resonance titrations for succinate and propionate in varying concentrations of the same salts are also shown. A method of converting thermodynamic stability constants from one ionic strength to another using a modified form of the Pitzer equations is presented with a computer program which performs the conversion. A novel method of obtaining complexation constants from protonation constants in varying media is proposed. Using optical microscopy, creaming rates and laser particle sizing, the affects of changing surfactant concentration, salt concentration, pH and shearing time for emulsions of ammonium nitrate solution in heptane with CRILL 43 are shown. Equations are derived for converting creaming rate data to droplet size information and a computer program for converting Malvern light intensity data in the anomalous regime (typical of water-in-oil emulsions) to size distribution data is presented. The computer model is validated against experimental data from this work and the literature and is used to make stability predictions for systems for which no data exists. Further uses for the model are discussed.
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Cohen, Michael H. "Collisional activation dynamics of ion systems associated with water /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488187763848448.
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Gaither, Scott P. "Biological Water: A Brief Review of Hydration Dynamics using Complex Systems." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532015941319059.
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Boulesbaa, Abdelaziz. "Ultrafast Vibrational Dynamics at the Solid/Water Interface." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/238898.
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ChemistryPh.D.
No doubt, water is the most important liquid on the planet. In addition to the obligatory need for water in life, water is widely used in diverse applications. In most applications if not all, water is interfaced with different materials, at different phases depending on the application. This unique value of water originates from its chemical structure, which is based on hydrogen bonding. Although these chemical bonding in bulk liquid and vapor water have extensively been investigated, in interfacial water are not yet fully understood. This thesis presents an investigation of ultrafast vibrational dynamics of hydrogen bonding in interfacial water. In a first chapter, the experimental technique and tools needed for the study of interfacial vibrational dynamics are exposed. In the first part of a second chapter, vibrational coherence dynamics of free OH stretch modes at the alumina/water interface are investigated. And in the second part, vibrational coherence dynamics of hydrogen bonded OH stretch modes at the calcium fluoride/water interface are investigated. To understand the dynamics of vibrational energy flow within an interfacial network of hydrogen bonding, the investigation of vibrational coupling dynamics at the calcium fluoride/water interface takes place in a third chapter. Unlike what has already been reported in this topic, in our work, the vibrational energy will be initially deposited at the second vibrational excited state, through an overtone transition.
Temple University--Theses
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Mager, Edward Michael. "Interactions Between Water Chemistry and Waterborne Lead Exposure to Freshwater Organisms." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/666.
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This dissertation characterizes the influences of water chemistry on the acute toxicity of lead (Pb) to two of the long-standing sentinel test organisms commonly employed by the United States Environmental Protection Agency (USEPA), the fathead minnow (Pimephales promelas) and daphnid (Ceriodaphnia dubia), for parameterization of an acute Pb Biotic Ligand Model (BLM). In addition, a toxicogenomic approach was employed to identify genes that might serve as molecular markers of Pb exposure and long-term effects, as well as provide new insights as to the underlying toxic mechanisms of chronic Pb exposure in P. promelas. The endpoints of growth, reproduction, Pb accumulation, prey capture ability, and swimming performance of P. promelas were examined to assess the influences of water chemistry during chronic Pb exposures and to potentially link microarray-identified genes to outcomes of ecological significance. Importantly, this work revealed that calcium does not protect against acute toxicity to C. dubia or chronic Pb accumulation by P. promelas, indicating that current hardness-based regulations are inappropriate and provide further support for the need for alternative approaches to setting environmental regulations for Pb. The findings reported herein should facilitate the arrival of such an approach in the form of a new acute Pb BLM. However, different responses with respect to the influences of water chemistry on the acute toxicity of Pb were exhibited by these species suggesting that development of separate BLMs for P. promelas and C. dubia should be considered to ensure adequate protection for both species. Furthermore, the influences of water chemistry were found to be inconsistent during acute and chronic Pb exposures to P. promelas and thus caution against inferring chronic effects from acute exposures. A number of Pb-responsive genes were identified that exhibited a strong potential for serving as robust indicators of Pb exposure and accumulation in P. promelas. While these genes also provided insight as to the likely toxic mechanisms of Pb, additional work will be necessary to firmly link these genes to chronic outcomes of ecological relevance in the context of ambient water chemistry.
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Wong, Wing-sze, and 黃穎詩. "Water chemistry in the Kam Tin basin, natural and authropogenic influences." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38605843.
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Raper, David William. "Acid deposition and water chemistry in the Derbyshire High Peak District." Thesis, Manchester Metropolitan University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328398.
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This thesis presents data from an integrated study of precip~tation, ground and surface water chemistry from 460 km of the Peak District, between May 1987 and April 1988. All samples have been analysed for a suite of nine major ions. Data have been used to: (1) describe temporal and spatial variability of acid precipitation and deposition; (2); examine the controls on precipitation chemistry; (3) describe the chemistry of sampled waters and elucidate catchment processes; and (4) examine the impact of bulk deposition on ground and surface water chemistry. The dense network of collectors has clearly identified significant small scale variability of precipitation chemistry across the study area. However, temporal variability is consistent with observations of other workers. It has been statistically demonstrated that calcium and non-marine sulphate have a close temporal and spatial association. This is hypothesised as being the result of atmospheric reactions between regional gaseous sulphur dioxide and extractive industry derived calcium. The resultant calcium sulphate is prinCipally removed by below cloud scavenging and dry deposition. All sampled groundwaters bave .a high acid neutralising capacity which illustrates the dominance of limestone solutional processes. Surface waters have relatively high concentrations of base cations indicating some buffering potential. However, high variability of bo~~ hydrogen and aluminium suggests a limited buffering capability during storm events. Advanced statistical techniques have demonstrated a complex association between surface water acidification and the bulk deposition of marine ions. This is consistent with the findings of other researchers. Cross and partial correlation have shown the mobility of aluminium in acid sensitive waters to be related to elevated loadings of hydrogen. This research has demonstrated the importance of finescale resolution in precipitation chemistry monitoring networks. Advanced statistical techniques have identified relationships between precipitation chemistry and ground and surface water quality in a geologically complex ..environment.