Dissertations / Theses: 'Water properties'

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Tasker, Alison Louise. "Water resistance properties of water-based biopolymer films." Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5847/.

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This thesis addresses both the theory and simulation of diffusion of moisture in water-based biopolymer films, whose preliminary use is as adhesives on glass bottles in the labelling industry. The first part explores the kinetics of dehydration of thin films of these biopolymer materials. The second part of the thesis deals with moisture intake into both dried thin films and into the wet biopolymer gel network. Mathematical simulations based on Fick's laws of diffusion have been developed as a tool to understand the underpinning mechanisms of diffusion and of evaporation to discover which, if either plays a more dominant role in controlling the dehydration process. By inputting a series of different initial and final moisture contents, a full spectra of scenarios has been examined to aid understanding of the dehydration process. Numerical calculations where diffusion is the controlling mechanism as well as simulations where evaporation controls the process have been considered and discussed. Models in which a combination of both diffusion and evaporation are equally important are also studied. Fixed and moving boundary conditions are applied to the models and compared with dehydration results obtained experimentally. A simple method has been developed to assess the rehydration process of a dried biopolymer film and similar simulations have also been constructed to describe the rehydration of a water droplet into the thin, dried films. A novel method to investigate the migration of water into casein biopolymer gels using acoustic techniques has been developed and validated. The preliminary results are promising, highlighting the potential capability of the method. As the composition of a material changes, the speed of a wave of sound being passed through the material changes, so by monitoring this change as a function of time, concentration profiles of the biopolymer material can be constructed. Simulated concentration profiles were successfully produced based on Fick's second law of diffusion, to obtain a diffusion coefficient dependent on both time and position. By fitting these curves to the experimental data, diffusion coefficients are obtained with values of the same order of magnitude as those calculated from the experiments on a dehydrating thin film of the same composition.

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Delle, Site Luigi. "Ab initio study of water." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322621.

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GUNT, HEMALI B. "WATER HANDLING PROPERTIES OF VERNIX CASEOSA." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1018024012.

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André, Tomas. "Benchmarking Physical Properties of Water Models." Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388336.

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Water is a fundamental part of life as we know it, and by that also a fundamental for biology, chemistry, and parts of physics. Understanding how water behaves and interacts is key in many fields of all these three branches of science. Numerical simulation using molecular dynamics can aid in building insight in the behavior and interactions of water. In this thesis molecular dynamics is used to simulate common rigid 3 point water models to see how well they replicate certain physical and chemical properties as functions of temperature. This is done with molecular dynamics program GROMACS which offers a complete set of tools to run simulations and analyze results. Everything has been automated to work with a python script and a file of input parameters. Most of the models follow the same trends and are valid within a limited temperature range.
Vatten är en av de fundamentala byggstenarna för liv, därmed är det även fundamentalt för biologi, kemi och delar av fysiken. Att förstå hur vatten beter sig och interagerar är en stor fråga inom dessa tre grenar av vetenskap. Med molekyldynamik går det att utföra numeriska simuleringar som kan användas som hjälpmedel för att bygga en djupare förståelse för riktigt vatten. I den här uppsatsen så har molekyldynamik använts till att simulera vanliga rigida 3 punkts parametiseringar av vatten för att se hur bra de kan replikera vissa egenskaper som funktioner av temperatur. Simuleringen är gjord med hjälp av molekyldynamik programet GROMACS som ger en fullständig uppsättning verktyg för att simulera och analysera molekylsystem. Alla simuleringar och analys är automatiserat med ett pythonprogram och en fil för parametrar. De allra flesta modeller följer liknande trender och är giltiga inom små temperaturintervall.

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JOHNSON, JAMES WESLEY. "CRITICAL PHENOMENA IN HYDROTHERMAL SYSTEMS: STATE, THERMODYNAMIC, TRANSPORT, AND ELECTROSTATIC PROPERTIES OF WATER IN THE CRITICAL REGION." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184147.

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The H₂O critical point defines the parabolic vertex of the p(T) vaporization boundary and, as a geometric consequence, a positive vertical asymptote for first partial derivatives of the equation of state. Convergence of these derivatives, isothermal compressibility and isobaric expansivity, to the critical asymptote effectively controls thermodynamic, electrostatic, and transport properties of fluid H₂O and dependent transport and chemical processes in hydrothermal systems. The equation of state for fluid H₂O developed by Levelt Sengers et a1. (1983a) from modern theories of revised and extended scaling affords accurate prediction of state and thermodynamic properties in the critical region. This formulation has been used together with the virial equation of state proposed by Haar et a1. (1984) and predictive equations for the static dielectric constant (Uematsu and Franck, 1980), thermal conductivity (Sengers et a1., 1984), and dynamic viscosity (Sengers and Kamgar-Parsi, 1984) to present a comprehensive summary of fluid H₂O properties within and near the critical region. Specifically, predictive formulations and computed values for twenty-one properties are presented as a series of equations, three-dimensional P-T surfaces, isothermal and isobaric crosssections, and skeleton tables from 350°-475°C and 200-450 bar. The properties considered are density, isothermal compressibility, isobaric expansivity, Helmholtz and Gibbs free energies, internal energy, enthalpy, entropy, isochoric and isobaric heat capacities, the static dielectric constant, Z, Y, and Q Born functions (Helgeson and Kirkham, 1974a), dynamic and kinematic viscosity, thermal conductivity, thermal diffusivity, the Prandtl number, the isochoric expansivity-compressibility coefficient, and sound velocity. The equations and surfaces are analyzed with particular emphasis on functional form in the near-critical region and resultant extrema that persist well beyond the critical region. Such extrema in isobaric expansivity, isobaric heat capacity, and kinematic viscosity delineate state conditions that define local maxima in fluid and convective heat fluxes in hydrothermal systems; at the critical point, these fluxes are infinite in permeable media. Extrema in the Q and Y Born functions delineate state conditions that define local minima in the standard partial molal volumes and enthalpies of aqueous ions and complexes; at the critical point, these properties are negative infinite. Because these fluxes and thermodynamic properties converge to vertical asymptotes at the critical point, seemingly trivial variations in near-critical state conditions cause large variations in fluid mass and thermal energy transfer rates and in the state of chemical equilibrium.

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Mader, Heidy Marita. "Water veins in polycrystalline ice." Thesis, University of Bristol, 1992. http://hdl.handle.net/1983/e6d58308-f291-4069-9196-b3661a395dc1.

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Kristensen, Aleksander. "Flow properties of water-based drilling fluids." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23107.

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The objective of this master thesis was to investigate the flow properties of water based drilling fluids, utilizing measurements in both the micro and macro scale. The research was performed on two realistic drilling fluids by the use of a viscometer, a rheometer and a realistic flow loop, where the latter represents the macro scale. The research outcome could possibly improve the understanding of flow behavior in wellbores, and remove uncertainties associated with annular friction. The two fluids utilized in the research was made up with the goal of having equal rheological qualities, when measured with a Fann 35 viscometer. A more thorough examination of the two fluid's rheology was then executed by using a Anton Paar MCR302 rheometer. The macroscopic properties was researched employing a flow loop, capable of simulating realistic wellbore conditions.The main outcome of this thesis is that even though two fluids appear to have the same rheoligical properties when measured on simple equipment, their fundamental different microscopic structure will exhibit variations when the fluids are utilized in real applications.Due to problems encountered when mixing the fluids, as well as problems with one of the fluids itself, not all intended experiments were conducted. The experiments should be replicated with an emphasis on temperature control, avoiding bubbles and foam, and be conducted within a shorter time period.

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Peng, Shuang Jiu. "Filtration properties of water based drilling fluids." Thesis, Heriot-Watt University, 1990. http://hdl.handle.net/10399/871.

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This thesis reports an experimental and theoretical study on filtration properties of water based drilling fluids under dynamic and static conditions. The tested muds cover Freshwater/Gypsum/Lignosulphonate mud and SeawaterlKCLlPolymer mud, bariteweighted and unweighted. The effects of the solid concentration, pressure and shear rate on the filter cake characteristics and the erodability were investigated. For static filtration experiments, all tests were conducted for two hours and the spurt loss, the filter cake thickness, the ratio of wet to dry cake mass and the cumulative filtrate volume against time were measured. For dynamic filtration experiments, however, only the spurt loss and the cumulative filtrate volume against time were measured and all tests were conducted for at least 8 hours. A general filtration equation was developed based on the cake filtration theory prevailing in the chemical engineering industry and it was utilised to obtain the modified classic static filtration equation and the dynamic filtration equation. The modified classic static filtration equation was then employed to fit the static filtration experimental data and the average specific static cake resistance and the effective filter medium resistance were calculated. The dynamic filtration equation showed a substantial agreement with the dynamic filtration experimental data. Using the static filter cake properties such as the ratio of wet to dry cake mass (m), the average specific dynamic cake resistance, the effective filter medium resistance and the dynamic filter cake erodability were calculated. In the study of the relationship between the static filtration data and the dynamic filtration data, an attempt of predicting the dynamic filtration data from the static filtration experimental data was conducted. Also, an attempt was carried out to predict the static filtration data and the dynamic filtration data in a sequential process. The experimental data suggests that a substantial difference exists between the specific resistances of static and dynamic filter cakes. No apparent distinction was found, however, between spurt loss and effective filter medium resistance. The reodability of dynamically deposited mud cake for Seawater/KCL/Polymer mud was found to be three fold for Freshwater/Gypsum/Lignosulphonate.

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Herlevi, Antti. "Inherent and apparent optical properties in relation to water quality in Nordic waters." Helsinki : University of Helsinki, 2002. http://ethesis.helsinki.fi/julkaisut/mat/fysik/vk/herlevi/.

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Dutta, Saikat Swapan. "Water absorption and dielectric properties of Epoxy insulation." Thesis, Norwegian University of Science and Technology, Department of Electrical Power Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9723.

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Characterization of Epoxy (diglycidyl ether of Bis-phenol A cured with Tri ethylene Tetra amine) without fillers was done. The Water absorption test at 95°C shows that at saturation the epoxy contains a water concentration of 2.089%. The diffusion coefficient of absorption is calculated as 0.021 cm2/s. The diffusion coefficient of desorption is calculated as 0.0987 cm2/s. The diffusion is almost 5 times faster than absorption. Also the material looses weight as the hydrothermal aging progresses. The water in the sample leads to chain scission which leads to the weight loss. The weight loss is more incase of absorption followed by desorption than only absorption. The chain scission leads to decrease in the mechanical strength by around 45%. The diffusion of water from the samples doesnt affect the mechanical strength of the materials. The glass transition temperature reduces by 20°C with water inside the sample. The diffusion of water out of the sample only increases by around 10°C. The Dielectric response of the material shows that after the water absorption the sample shows high losses at lower frequencies. Also the increase in the real part of the permittivity increases with low frequency. The rapid increase in the real art of the permittivity of the material at lower frequencies can be attributed to a polarization at the electrode due both to accumulation of the charge carriers and to chain migrations. The breakdown test of the samples shows that with water in the sample the breakdown strength of the material decreases by 10 KV, but the material regains its dielectric strength when the water is diffused out. This shows that the chain scission and weight loss of the samples has no or minimum effect on the dielectric strength of the sample

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Barker, David Colin. "The lubricating properties of oil-in-water emulsions." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294971.

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Andersson, Ida, and Anders Hedvall. "Relationships Between Skin Properties and Body Water Level." Thesis, KTH, Medicinsk teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-133438.

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A need for a quantitative method to determine body water level has been identified by a team of Clinical Innovation Fellows at the Centre for Technology in Medicine and Health (CTMH). A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing. A possible solution is a sensor that would measure alterations in skin properties due to changes in total body water. CTMH has had an idea of such a sensor, which is evaluated in this work. At an early stage of this evaluation process, it became clear that the research regarding correlations between skin properties and body hydration level was not sufficient to warrant the initiation of a sensor development process. Therefore, the main objective of this thesis became to investigate such correlations. An extensive literature review is presented, from which an experiment was developed. The experiment was performed on four human test subjects and involved measurements of skin thickness and elasticity parameters, before and after a weight loss of 3.2-3.7 % due to dehydration. The results showed clear decreases in skin thickness and indications of alterations in skin distensibility as well as in the skin’s immediate elastic response to applied negative pressure. It could also be seen that skin at different body sites does not respond in the same way - calves showed more distinct results than thighs and volar forearm. The material provided in this thesis encourages further studies of the correlation between the mentioned properties and total body water. If a predictable correlation can be found, a sensor development process could start. A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing.
Ett behov av att kvantitativt kunna mäta kroppens vattennivå har identifierats av Clinical Innovation Fellowship vid Centrum för Teknik i Medicin och Hälsa (CTMH). Ett tillförlitligt sätt att mäta kroppens vattennivå skulle gynna hälso- och sjukvården på många sätt då ingen optimal metod är tillgänglig i dagsläget. En möjlig lösning skulle kunna vara en sensor som mäter variationer i hudegenskaper till följd av förändringar i kroppens vattennivå. CTMH har haft en idé om en sådan sensor, vilken utvärderas i detta arbete. I ett tidigt skede av utvärderingsprocessen framkom det tydligt att tillräcklig forskning saknades gällande korrelationer mellan hudens egenskaper och kroppens vattennivå. Det huvudsakliga syftet med detta masterexamensarbete blev därför att undersöka sådana korrelationer. En omfattande litteraturgransking gjordes, och utifrån denna utformades ett experiment. Experimentet utfördes på fyra testpersoner och innefattade mätningar av hudens tjocklek samt elasticitetsparameterar. Dessa utfördes före och efter viktnedgång av 3,2-3,7 % till följd av vattenförlust. Resultaten visade på en tydlig minskning av hudtjockleken samt indikationer på förändringar av hudens tänjbarhet samt dess omedelbara elastiska respons vid pålagt negativt tryck. Det visade sig också att huden inte reagerar på samma sätt på olika kroppsdelar - vader visade tydligare förändringar jämfört med lår och armar. Det material som presenteras i detta examensarbete uppmuntrar till fortsatt utredning av korrelationer mellan de nämnda hudegenskaperna och kroppens vattennivå. Om det går att förutse korrelationer finns det förutsättningar för att påbörja utveckling av en sensor.

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Burnham, Christian James. "Structural and dynamical properties of mathematical water models." Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299208.

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Sparks, Kevin A. "Configurational properties of water clathrates through molecular simulation." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13759.

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Masilela, Nkosiphile. "Photophysical and photoelectrochemical properties of water soluble metallophthalocyanines." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1004991.

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This work presents the synthesis, characterization, photophysicochemical and photoelectrochemical properties of anionic octa-caboxylated (MOCPcs), tetra-sulfonated (MTSPcs) and quaternized cationic (Q(T-2-Py)MPcs) water soluble aluminium, gallium, silicon, titanium and zinc phthalocynines. The peripherally tetra-substituted cationic (Q(T-2-Py)MPcs) and anionic (MTSPcs) were found to be aggregated in aqueous media, yet the octa-carboxylated (MOCPcs) counterparts were monomeric in solution. Cremophor EL (CEL) was used as a disaggregating agent, all the aggregated complexes disaggregated partially or completely in the presence of CEL. The photophysicochemical properties of aggregated complexes were investigated both in the presence of CEL and in aqueous media of pH 11 alone. Low triplet, singlet oxygen and fluorescence quantum yield were obtained in aqueous media (especially for the aggregated complexes) but a high improvement was achieved upon addition of CEL. The gallium complexes ((OH)GaOCPc and (OH)GaTSPc) showed good photophysicochemical properties with higher triplet and singlet oxygen quantum yields. For photoelectrochemistry the (MPcs) dyes were adsorbed to nanoporous ZnO, electrodeposited in the presence of eosin Y as structure directing agent (SDA) on FTO substrates by refluxing or soaking the films in a solution containing the dye of interest such that a full surface coverage was achieved. Quaternized cationic (Q(T-2-Py)MPc) and tetrasulfonated (MTSPcs) phthalocyanines formed strong aggregates when deposited on the surface of FTO/ZnO substrate leading. High external (IPCE) and internal (APCE) quantum efficiencies of up to 50.6% and 96.7% were achieved for the OTiOCPc complex. There was a lower overall cell efficiency for quaternized and tetrasulfonated metallophthalocyanines because of the strong aggregates when they were on the surface of the electrodes. Among the studied materials, OTiOCPc gave the highest overall cell efficiency of phthalocyanine electrodeposited on ZnO of so far  = 0.48%.

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Furlong, P. J. J. "Salt effects in nonionic surfactant/dodecane/water systems." Thesis, University of Nottingham, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235449.

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Spooner, Peter T. "Investigating the use of cold-water corals as archives of past ocean water properties." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702452.

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Cold-water corals are a relatively new archive of past ocean conditions. They are found in areas that sedimentary records struggle to record, and their aragonite skeletons can be dated using precise uranium-series techniques. Arguably, the most successful use of cold-water corals in palaeoceanography has been using radiocarbon to trace water mass ages and mixing. For example, these techniques have revealed discrete periods of Southern Ocean deglacial ventilation, a likely driver of the deglacial rise in atmospheric C02. However, the use of cold-water corals in palaeoceanography is hampered by slow dating procedures and a scarcity of palaeocean proxies that are free of biological mediation (vital effects). My work aims to address these issues and improve the utility of the cold-water coral palaeocean archive.

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Scovell, Dawn Laura. "Dielectric properties and ionization of water in high interfacial electric fields /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9877.

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Strömbeck, Niklas. "Water quality and optical properties of Swedish lakes and coastal waters in relation to remote sensing /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5037-7/.

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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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Gick, M. M. S. "The diffusion of aviation fuel and water in polysulphide sealants." Thesis, London Metropolitan University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380666.

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The diffu~ion and permeation of aviation fuel (Avtur) and water in commercial and 'model' polysulphide sealants have been studied using simple gravimetric techniques. For Avtur, the mass uptake behaviour is explicable in terms of normal, Fickian diffusion, and the diffusion coefficient determined has been found to be independent of the experimental method and concentration of the liquid. Water, however, exhibits anomalous diffusion behaviour. Mass uptake by the polysulphides is high and equilibrium is not reached after several months. There is no correlation between the results of permeation, absorption and desorption experiments except at low water concentration ... ,,~ . These anomalies have been explained in terms of the formation of water droplets within the rubber. This study shows that the amount of water absorbed is dependent upon the amount and nature of the curing agent residues. The results have been analysed in terms of the osmotic and water vapour pressure and two equations have been derived which satisfactorily predict the amount of water absorbed at equilibrium. It has been shown that the effect of the water droplets on permeation is negligible, and hence the diffusion coefficient found is a measure of the true rate of diffusion. In contrast, the effect of the droplets on mass uptake experiments is large and the apparent overall diffusion rate is greatly reduced. The apparent diffusion coefficient found is dependent upon the water concentration and the concentration of the water-soluble impurities. An equation has been derived showing the relationship between these variables. The results of this work show that the elastic strength of the rubber has negligible effect in determining the water uptake at equilibrium and the apparent diffusion coefficient. However, deterioration in adhesive and cohesive strength occurs with water uptake. At high uptake some of this loss is irreversible. The deterioration in properties is mainly due to breakage of weak physical bonds and plasticisation effects. -

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Ekblad, Jonas. "Influence of Water on Coarse Granular Road Material Properties." Doctoral thesis, Stockholm : Byggvetenskap, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4329.

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Robillard, David J. "Non-Gaussian properties of waves in finite water depth." Thesis, Monterey, California. Naval Postgraduate School, 1996. http://hdl.handle.net/10945/8738.

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Malcolmson, Carole A. "The physicochemical properties of nonionic oil-in-water microemulsions." Thesis, King's College London (University of London), 1992. https://kclpure.kcl.ac.uk/portal/en/theses/the-physicochemical-properties-of-nonionic-oilinwater-microemulsions(4315649d-d2d1-497d-9a76-05bc06f7f9a1).html.

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Doyle, Peter John. "Effects of surfactant on properties of triglyceride/water systems." Thesis, Liverpool John Moores University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278945.

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Holland, Sara. "Structure and properties of novel water-in-oil microemulsions." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336159.

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Reichert, Jutta. "The production and water filtration properties of porous hydroxyapatite." Thesis, University of Nottingham, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239927.

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John, Wilson. "Synthesis, properties and analysis of polydadmac for water purification." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/19531.

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Thesis (PhD)--Stellenbosch University, 2008.
ENGLISH ABSTRACT: This study concerns the synthesis, properties and quantitative analysis of polydiallyldimethylammonium chloride (polyDADMAC), a water-soluble polymer used world-wide for potable water purification. The special interest in this polymer is the result of its widespread use and the current lack of adequate analytical methods for it. This is especially important for water treatment organisations. A novel gel permeation chromatography (GPC) method was developed and evaluated for polymer analysis. The scope was extended to determine the presence of unreacted monomer (DADMAC) as well as the percentage active polymer. polyDADMAC was first prepared using a known synthesis method. The product was purified and characterized by GPC and 13C-NMR spectroscopy. New and conclusive evidence of the existence of a five-member pyrrolidine ring system was obtained. A proposed mechanism of polymerization was determined. The activity of the synthesized polyDADMAC was evaluated and it was found to perform effectively as a coagulant. The physical and chemical properties of polyDADMAC were then studied under simulated water treatment conditions. The polymer reaction with chlorine revealed the formation of trihalogenated methane compounds (THMs). Gas chromatography–mass spectrometry (GC–MS) was used to conclusively identify the formation of chloroform. The polymer stability under different conditions of heat exposure, UV radiation and pH variations was studied. GPC results indicated that polyDADMAC is a very stable polymer and undergoes structural change only when subjected to extremes of pH, temperature and UV conditions. Results of a short study on microbial degradation indicated growth of the cultures, and subsequent polymer degradation. Reactions of polyDADMAC were concluded with a study of the impact of ozone on polyDADMAC. GPC results indicated a significant change in the ozonated polymer peak profile. Analytical methods to determine polyDADMAC residues in water were reviewed and critically evaluated. Methods based on complex formation/spectroscopy suffered from severe limitations and produced no meaningful results, contrary to claims made by previous researchers. Colloid titration based on an established method was promising but required extensive modification for quantitative analysis. Finally four novel methods were developed, including: solid phase extraction, membrane filtration-GPC, the HACH complexation method, and a GPC method with indirect UV detection. The study is concluded with a chemical risk assessment that indicated minimal human health risks associated with the production and use of polyDADMAC.
AFRIKAANSE OPSOMMING:Hierdie studie behels die sintese, eienskappe en kwantitatiewe analise van polidiallielmetielammoniumchloried (polyDADMAC), 'n wateroplosbare polimeer wat wêreldwyd vir drinkwatersuiwering gebruik word. Die belangstelling in hierdie spesifieke polimeer is as gevolg van die wydverspreide gebruik daarvan en die feit dat daar tans onvoldoende eenvoudige analitiese metodes daarvoor bestaan. Dit is veral belangrik vir waterbehandelingsorganisasies. 'n Nuwe gelpermeasiechromatografie (GPC) metode is ontwikkel en geevalueer vir die analise van hierdie polimeer. Die omvang van die studie is later uitgebrei om die teenwoordigheid van ongereageerde monomeer (DADMAC) asook die persentasie aktiewe polimeer te bepaal. polyDADMAC is eers volgens 'n bekende sintesemetode berei. Die produk is gesuiwer en gekarakteriseer m.b.v. GPC en 13C-KMR. Nuwe bewyse vir die bestaan van 'n vyflid pirollidoonringsisteem is verkry. 'n Meganisme vir hierdie polimerisasie metode is vasgestel. Die aktiwiteit van die bereide polyDADMAC is geevalueer en daar is bevind dat dit effektief as koaguleermiddel optree. Daarna is die chemiese en fisiese eienskappe van polyDADMAC onder gesimuleerde waterbehandelingskondisies bepaal. polyDADMAC het met chloor gerageer om trihalogeneerde metaanverbindings (THMs) te vorm. Gaschromatografie–massa-spektrometrie (GC–MS) is gebruik om die ontstaan van chloroform te bevestig. Daarna is die stabiliteit van die polimeer onder verskei reaksiekondisies bepaal: hitte, UV-bestraling, en pH. GPC-resultate het aangeduiui dat polyDADMAC baie stabiel is en ondergaan strukturele veranderings slegs onder uiterste kondisies van pH, temperatuur en UV. 'n Kort studie van die effek van mikro-organismes op polyDADMAC het egtermikrobiese kultuurgroei met die gevolglike afbreek van die polimeer getoon. Resultate van 'n studie van die impak van osoon op polyDADMAC het getoon dat daar 'n groot verandering in die GPC-profiel van die ge-osoneerde vorm van die polimeer was. Verdere analitiese metodes wat al gebruik is om polyDADMAC residue in water te bepaal, is uitgevoer en krities geevalueer. Metodes gebasseer op kompleksvorming/ spektroskopie het erge beperkings gehad en het nie betekenisvolle resultate gelewer nie. Dit was in teenstelling met wat voorheen deur ander navorsers bevind is. 'n Kolloiedtitrasie gebasseer op 'n bestaande metode het goeie resultate gelewer maar het omvattende veranderings benodig om kwantitatiewe resultate te lewer. Ten slotte is vier nuwe metodes ontwikkel: soliede fase-ekstraksie, membraanfiltrasie-GPC, die HACH-komplekseringsmetode, en 'n GPC-metode met indirekte UV-waarneming.. Die studie is afgesluit met 'n bepaling van die chemiese risiko wat poly DADMAC vir die gesondheid van die mens inhou. Daar is tot die gevolgtrekking gekom dat die produksie en gebruik van poly DADMAC slegs‘n minimum gesondheidsrisiko inhou.

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29

Qi, Jiaguo 1959. "Spectral properties of paddy rice with variable water depth." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277119.

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An experiment was conducted to determine whether the water depth (above soil) and soil type would have any influence on the multispectral reflectances of paddy rice, and their calculated vegetation index values. The results showed that, when vegetation cover was low (below 600 grams of dry biomass per square meter), the near infrared (NIR) reflectances decreased very little with water depth. The same was true for red reflectances, but to a lesser degree. Overall the changes were not significant at 0.05 level of significance when the water depth was increased from 2.5 centimeters to 10 centimeters. When the vegetation cover became higher most NIR and red reflectances did not show a significant decrease with the increase of the water depth, and sometimes they even increased slightly up to a water depth of 6.4 cm. Nevertheless both rice cover and water depth as well as soils played an important role in the reflectance pattern in red and NIR bands. Some index values increased and some decreased depending on water depth and rice cover. Statistical analysis of the data showed that rice multispectral responses were mainly controlled by vegetation and minimally influenced by soil and water depths.

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Tan, Bowen. "Poly(lactic acid) nanocomposites : water barrier properties and electrospinning." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/24611.

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The PhD thesis investigated poly(lactic acid) nanocomposite in terms of water barrier properties and electrospinning. The thesis addresses two different but related topics. The first topic is improvement of the water vapour barrier properties of PLA films. The effect of montmorillonite clay and its alignment on water vapour permeability and the effect of crystallinity (introduced by annealing) on nanoclay alignment and barrier properties were investigated (Chapter 4). PLA nanocomposites containing 0 to 5 wt.% montmorillonite layered silicate were prepared. Both amorphous and semi-crystalline PLA nanocomposite films were obtained by compression moulding. Thermal properties of the samples were measured by DSC. The nanoclay dispersion was measured using TEM and WAXD. Water vapour transmission rates through the films were measured at 38℃ and at a relative humidity of 90%. A new tortuous path model was developed to quantify the effect of crystallinity, nanoclay concentration and nanoclay alignment on water vapour permeability and showed a good fit with the experimental data from the annealed PLA nanocomposites.

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31

Malykhina, A. V., G. M. Cherkashina, and O. M. Rassokha. "Research of properties of polyamide products with reduced water." Thesis, ТОВ "ТВОРИ", 2020. http://repository.kpi.kharkov.ua/handle/KhPI-Press/48822.

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32

Jayasinghe, Ashini Shamindra. "Exploring the unique water properties of metal-organic nanotubes." Diss., University of Iowa, 2017. https://ir.uiowa.edu/etd/5521.

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Metal-organic nanotubular (MON) materials have garnered significant attention in the recent years not only due to the aesthetic architecture but also due to the interesting chemical and physical properties that have been reported for these compounds. The number of MONs reported in the literature are limited compared to metal organic frameworks due to synthetic challenges and difficulties in crystal engineering. These types of materials are of interest given their one-dimensional channels that lead to their potential application in advanced membrane technologies. In Forbes group, a uranium-based metal-organic nanotube (UMON) was synthesized using zwitterionic like iminodiacetic acid (IDA) as the ligand. IDA ligand chelates to the U(VI) metal center in a tridentate fashion and doubly protonated IDA linker connects the neighboring uranyl moieties until it forms hexameric macrocycles. These macrocycles stack into a nanotubular array due to supramolecular interactions. Single crystal X-ray diffraction studies displayed there are two crystallographically unique water molecules that can be removed reversibly at 37 °C. UMON indicated selectivity to water, the selectivity of this material was analyzed using solvents with different polarities, sizes, and shapes. In the current body of work, dehydrated UMON crystallites were exposed to these solvents (in liquid and vapor phase) and studied using TGA coupled FTIR set up, confirming the highly selective nature of UMON. Kinetic studies were also conducted using an in-house built vapor adsorption setup confirmed the water uptake rate of the nanotube depends on the humidity of the environment. Uptake rates were estimated using a simple kinetic model and indicated enhanced hydration compared to other porous materials. One of the hypotheses regarding the interesting properties of UMON is that the uranium metal center might play a central role in the selectivity of this material. To test this hypothesis, a similar uranium based metal-organic nanotube containing 2,6-pyridine dicarboxylic acid (UPDC) as the ligand was synthesized and its properties were compared to that of the UMON material. UPDC did display some selectivity based upon size exclusion but did not exhibit the same selectivity to water that is observed for UMON. Different transition metals were also incorporated into the nanotubular structures to determine the influence of dopants on the observable properties. Only small amounts of transition metal dopants were incorporated into the structure, but it increased the stability under high humid environment. Attempts to incorporate transition metal dopants in the UPDC led to the formation of novel chain structures.

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33

GARBUIO, VIVIANA. "Microscopic dynamics and excited state properties of liquid water." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2008. http://hdl.handle.net/2108/624.

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Water is the major chemical constituent of our planet's surface and it is essential for living organism survival; many biochemical and industrial processes occur in aqueous solution and the role of the solvent in the reactions is crucial. The comprehension of the chemical and physical nature of water has been a long-standing goal of science, and liquid water continues to attract intense interest and motivate a large number of experimental and theoretical works. Recently, however, the theoretical studies of water have mostly focused on its structure and ground state properties whereas less effort has been dedicated to its electronic structure and optical absorption spectrum. As a consequence, experimental data about excited states are not yet completely understood. Simultaneously, in the last years, great attention has been devoted to the study of water confined in different nanoporous systems, or in proximity of macromolecules and surfaces, because of its biological and technological importance (water in biology is always confined). Up to now, however, there is no general theory predicting the behavior of confined liquids or the relative importance of surface interaction versus confinement. The present work focuses on two complementary aspects of water: its excited state properties, very important in many chemical reactions and therefore fundamental to advance in many research fields, and the proton microscopic dynamics in confined water, which is interesting for many biological processes such as catalysis, protein folding or ionic transport in membranes. These topics are faced with different investigative approaches, both theoretical and experimental. The electronic and optical properties of liquid water are studied with ab-initio theoretical calculations, taking into account both self-energy and excitonic effects in the framework of many-body perturbation theory. The study of the proton microscopic dynamics of confined water has been instead made with deep inelastic neutron scattering experiments, performed at the ISIS spallation neutron source.

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34

Patel, A. N. "The influence of water on the compressional properties of some solids." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374737.

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35

Cederlund, Anna Angelica. "Walking on water : mechanical and material properties of articular cartilage in relation to water content." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=230580.

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Articular cartilage is a tough and resilient tissue lining the ends of articulating bones. It provides a smooth surface for joint locomotion as well as transmitting the force between bones. The main components of articular cartilage are collagen (20% w/w), proteoglycans (10% w/w) and water (70% w/w). The interactions between these three give the tissue its special characteristics. Water as a molecule is often forgotten when considering the mechanical properties of articular cartilage. This thesis aims to increase our knowledge of the role of water molecules in the load bearing mechanisms of the tissue. It will also investigate the material properties of cartilage as hydrogel. Different rates of loading (impact and slow compression) were used on partially dehydrated articular cartilage (bovine and human). The impact was also recorded using high-speed video cameras. Values of modulus of elasticity, Poisson's ratio, energetic coefficient of restitution were measured together with viscoelastic spectra, by Fourier transformation, and Dynamic Mechanical Analysis. Differential scanning calorimetry (DSC) was also performed on bovine and human articular cartilage, as well as transmission electron microscopy where different freeze substitution solvents were used. The stiffness of the tissue increased and the energetic coefficient of restitution decreased with decreasing water content. Cartilage explants had a smaller volume at the point of full strain than at the start of the impact and this volume loss was associated with the level of hydration of the tissue. Poisson's ratio was not associated with the water content of the tissue. The DSC showed that the water existed in the tissue in different environments, as the exothermic traces showed melting patterns with multiple peaks. Transmission electron micrographs revealed an area surrounding the collagen molecules that could be associated water. These results indicate that water might exist in a structured way in the tissue, and that it is important for the mechanical capabilities of the tissue.

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36

Strömbeck, Niklas. "Water Quality and Optical Properties of Swedish Lakes and Coastal Waters in Relation to Remote Sensing." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-670.

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Semi-analytical models for remote sensing of water quality parameters need to be parameterized with specific inherent optical properties. In this thesis, data on specific inherent optical properties of Swedish lakes and coastal waters is presented. Also, the problems of measuring in situ spectral backscattering are addressed. It is shown how measured specific inherent optical properties are used to parameterize semi-analytical bio-optical models. The models are then used to produce large synthetic data sets based on the distribution of water quality parameters, and from these data sets, band ratio or single band ratio algorithms for remote estimation of water quality parameters are constructed. A similar model was also used to calculate under water PAR from measured water quality parameters.

The specific inherent optical properties of Swedish lakes and coastal waters are very similar to earlier reported data from the oceanic environment. However, different relations of the water quality parameters will affect the inherent optical properties absorption and backscattering. The absorption spectra are dominated by yellow substance with terrestrial origin. Phytoplankton absorption is low, and account in general only for about 10 % of the total absorption in regions where phytoplankton pigments are active. The spectral backscattering is dominated by suspended particulate inorganic matter. Phytoplankton backscattering is almost negligible, except in cases where the phytoplankton community is dominated by highly scattering cyanobacteria. Experiences from remote sensing campaigns and modeling shows that remote chlorophyll estimation is most effective at longer wavelengths, where the absorption of yellow substance is low. However, modeling also predicts that large uncertainties have to be expected in the estimation of chlorophyll, both from variation in the specific phytoplankton absorption and from influences of other optically active water quality parameters.

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37

Chen, Shukun. "Rheological Properties of Oil in Water Emulsions and Particulate Suspensions." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2155.

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This thesis aims at a better understanding of the rheologicalproperties of the important colloids in oil industry, i.e. suspensions, emulsions and waxes.

The rheology of suspension system is a complex field influenced by a large range of variables. In this work, we mainly focused on the rheological properties of suspensions as a function of volume fraction of particles, particle size, surface properties, shear rate, and the nature of continuous mediums. The investigated suspensions behaved as Newtonian fluids at dilute concentration, whereas, shear thinning properties were observed at high volume fractions. The shear thinning effect increased with decreasing particle size. Ionic strength and pH are both factors affect particle interactions and consequently the rheological properties of suspensions: large and strong aggregates were formed at the isoelectric point, due to the strong attraction between particles at this point. The larger aggregates results in higher viscosity, yield stress, storage moduli and shear thinning effects. The relative viscosity of all the suspensions can be reasonably well fitted with the Krieger and Dougherty model.

Wax precipitation and deposition is a recurring challenge in transportation of crude oil. To better understand and explain these phenomena, the crystal growth of two model waxes was determined as a function of concentration, cooling rate and cooling conditions (static or dynamic). The flow and viscoelastic behaviours were investigated around the wax precipitation temperature, and the yield stress was determined after both dynamic and static cooling. Interpretation of the results was carried out in view of crystal growth and microstructure of the wax crystals.

Rheological properties of wax containing water-in-oil emulsions stabilized by asphathenes were also studied. Temperature scans of viscosity, flow measurements and yield stress measurements were carried out on these systems. The effects of water cut, amount of asphaltenes and amount of waxes were investigated. Wax content and water cut have the most pronounced effect upon the viscosity and yield stress of the systems.

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38

Oztoprak, Ayse Feray. "Investigation Of The Rheological Properties Of Cayirhan Coal-water Mixtures." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607861/index.pdf.

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In this thesis, coal-water mixtures (CWM) with Ç
ayirhan lignite were prepared to optimize the parameters of CWM having an ideal behavior which means that at maximum coal loading, relatively stable at static and dynamic conditions and exhibit low viscosity. For this purpose, the effect of the parameters such as pulp density, amount of chemical agents, particle size distribution, addition of methanol and pulp pH were investigated. Results showed that increasing pulp density negatively affects viscosity and allowable maximum pulp density was obtained as 60% when the particle size distribution has a d50 value of 22.82 µ
m. The optimum amount of chemical agent was found as 0.9%, having 10% Na-CMC (Sodium Carboxymethyl Cellulose) and 90% PSS (Polystyrene Sulfonate). Minimum viscosity was achieved when the pulp pH was in natural conditions (pH=6.85). Addition of methyl alcohol increased the viscosity of CWM.

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39

Eriksson, Anders Olof. "Water Runoff Properties for Expanded Clay LWA in Green Roofs." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23326.

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A lightweight aggregate (LWA) is a material that has a lower density than rock aggregates. There are many civil engineering application possibilities for LWA. A potential field of application for expanded clay LWA is as a storm water retaining layer in green roofs. In order to design reliable structures of green roofs, more knowledge about the characteristics of the material is needed. The purpose of this master thesis was to test if the software SEEP/W is an appropriate tool for simulation of water runoff from a green roof, designed with expanded clay LWA. The numerical modeling was not performed for all types of expanded clay LWA, but on crushed Leca® 4-10mm and round 10-20mm alone. To test if SEEP/W is advisable tool for simulating water flow in expanded clay LWA, a back calculation of a laboratory experiment was done. The purpose of back calculating the experiment is to calibrate a numerical model and then use it for a full scale ideal roof. Thereafter a sensitivity analysis of the SEEP/W input parameters was performed. It was possible to back calculate the laboratory experiment, meaning obtaining the same relation between water going in and water going out of the tested Leca® material. However, a lot of numerical problems occurred in the simulations. Unrealistic results were displayed, especially for Leca® 10-20mmR. In order to improve the performance of the material, and thereby obtain better water retaining characteristic, a suggestion is to increase the porosity and lower the saturated hydraulic conductivity for the expanded clay LWA materials in order to obtain a higher attenuation.

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40

Tay, Hwee Koon. "Barrier properties of water-borne polymeric coatings and corrosion protection." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363999.

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41

Caccamo, Lorenzo [Verfasser]. "Photoelectrochemical Properties of InGaN Photoanodes for Water Splitting / Lorenzo Caccamo." München : Verlag Dr. Hut, 2018. http://d-nb.info/1156510503/34.

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42

Drew, Christopher W. "Mechanical Loading for Modifying Tissue Water Content and Optical Properties." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/32714.

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The majority of the physical properties of tissue depend directly on the interstitial or intracellular concentration of water within the epidermal and dermal layers. The relationship between skin constituent concentrations, such as water and protein, and the mechanical and optical properties of human skin is important to understand its complex nature. Localized mechanical loading has been proven to alter optical properties of tissue, but the mechanisms by which it is accomplished have not been studied in depth. In this thesis, skinâ s complex nature is investigated experimentally and computationally to give us better insight on how localized mechanical loading changes tissues water content and its optical properties. Load-based compression and subsequent increased optical power transmission through tissue is accomplished to explore a relationship between localized mechanical loading and tissue optical and mechanical properties. Using Optical Coherence Tomography (OCT), modification of optical properties, such as refractive index, are observed to deduce water concentration changes in tissue due to mechanical compression. A computational finite element model is developed to correlate applied mechanical force to tissue strain and water transport. Comprehensive understanding of the underlying physical principles governing the optical property changes within skin due to water concentration variation will enable future development of applications in the engineered tissue optics field.
Master of Science

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43

Martinsdotter, Linnea. "Fiber based biocomposite material with water and grease barrier properties." Thesis, KTH, Fiber- och polymerteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298184.

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Syftet med denna studie var att utveckla en biokomposit med både fett-och vattenbarriär. Material med dessa egenskaper innehåller idag ofta PFAS-molekyler (per- och polyfluorerade alkylsubstanser). Det är av stor betydelse att byta ut dessa mot ett biobaserat alternativ då de är giftiga och ackumuleras i naturen. Biokompositen utvecklades genom att kombinera icke-trä pappersmassa (75%) och trä pappersmassa (25%) som matris. Därefter tillsattes olika biobaserade additiv i våtände för att påverka materialets egenskaper. Proverna testades på deras dragstyrka, vattenavvisning och fettavvisning. Den stora utmaningen var att lyckas med fettavisningen. 1% Polysackarid 1 tillsammans med 0.5% sizing komponent var det provet som gav bäst resultat. För att utvärdera denna metod gjordes en jämförelse med ytbehandling. Det gjordes genom att stryka på några av de tidigare använda additiven på ytan av matrisen. Ytbehandlingen visade sig ha en större påverkan på fettavvisningen men med liknande eller sämre påverkan på vattenavvisningen. Nackdelen med denna metod är att den kräver ett flertal extra steg i produktionen.
The aim of this thesis work was to develop a pulp-based biocomposite material with good water and grease barrier properties. It is important to achieve such properties to able to replace PFAS (poly- and perfluoroalkyl substances) molecules due to their toxicity and accumulation. Different types of pulp were evaluated as the matrix and the optimal matrix was based on non-wood pulp (75%) with wood pulp 1 (25%). This was also combined with several different additives in the wet-end. The samples were tested for their tensile strength, water resistance and grease resistance. The biggest challenge was to achieve adequate grease resistance. 1% Polysaccharide 1 together with 0.5% sizing agent was one of the better samples. It was clear the additives affected each other when used in combination with each other which indicates that wet end chemistry is complex. For a comparison, some additives were also tested as coatings. This technique resulted in better grease resistance but requires several extra steps in the production.

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44

Lam, Edyta. "The synthesis of water-soluble polymers with drag reducing properties." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/17952.

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The objective of work described in this thesis was to synthesize water soluble polymers with drag reducing properties that would expand the understanding of the relationship between the molecular structure of polymers and drag reduction performance. The additional aim of this study was to identify suitable additives that would enable removal of associating polymers from the low permeability reservoirs. The copolymers of acrylamide and two hydrophobic monomers, n-decyl- and n-octadecyl acrylamide were prepared using micellar polymerisation. Polymers of N-hydroxyethyl acrylamide were also prepared via the same method. Water soluble polymers of styrene and butadiene were acquired by sulfonation of poly(styrene-block-butadiene) with acetyl sulfate. The evidence of the incorporation of hydrophobic monomers, sulfonic acid groups into copolymers and the concentration of hydrophobic moieties was studied using NMR, FT-IR and Elemental Analysis. The influence of the degree of sulfonation on the flexibility of polymers and polymer degradation temperatures were investigated by DSC, DMA and TGA. The associating properties of polymers were studied using Dynamic Light Scattering and rheology. The drag reducing properties were quantified using a standard rheometer equipped with a Couette double-gap measuring geometry, by calculating the percentage of drag reduction (% DR) based on apparent viscosity. The extent of adsorption and desorption of polymers from silica was studied by Total Organic Carbon. From the obtained results it was clear that the associating properties of polymers synthesised in this thesis were dependent on the concentration of hydrophobic moieties. In addition, the formation of hydrophobic associations and the polymer coil dimensions were found to greatly influence the drag reducing properties and shear resistance of copolymers. It was found that hydrophobically modified polyacrylamide promoted higher drag reduction in comparison to unmodified polyacrylamide. In addition, introduction of a small amount of hydrophobic moieties was found to impart drag reducing properties in poly(N-hydroxyethyl acrylamide). Moreover, water soluble sulfonated poly(styrene-block-butadiene) showed high drag reduction efficiency at extremely low molecular weights below the required lower molecular weight limit necessary to produce excellent drag reduction effect. Furthermore, the sulfonation of poly(styrene-block-butadiene) resulted in the reduced thermal stability of polymers and an increase in the degree of sulfonation resulted in the decrease in the flexibility of polymer chains. The extent of adsorption of polymers of acrylamide on silica was found to increase with molecular weight of polymers and was higher for hydrophobically modified polyacrylamide due to the formation of intermolecular associations between copolymer chains. The desorption capability of copolymers with the aid of Cyclodextrin was demonstrated and was found to depend on the type of Cyclodextrin used and on the concentration of hydrophobic moieties. Nearly 100 % of the adsorbed polymer was recovered when even small concentrations of β-Cyclodextrin were applied. Additionally, partial desorption of polyacrylamide with the aid of α and β-Cyclodextrin was also achieved.

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45

Villanoy, Cesar Laurel. "Modification of the throughflow water properties in the Indonesian seas." Thesis, The University of Sydney, 1993. https://hdl.handle.net/2123/26591.

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Vertical mixing in the Indonesian Seas has been considered to be responsible for the apparent freshness of the throughﬂow when 'it enters the Indian Down. A three-dimensional primitive equation numerical model of the Indonesian Seas forced with a prescribed throughflow, transport consisting of North Pacific waters, is used to determine local dynamic processes which may modify the characteristics of the throughﬂow properties. The lack of long-term current measurements in the Indonesian Seas presents some difﬁculties in determining the certainty of the derived velocity ﬁelds. As an alternative, the model temperature and salinity fields are compared to observed hydrographic data which has a relatively better coverage throughout the Indonesian Seas. A 15 Sv net transport through the Indonesian Seas is suggested based on the model’s more realistic reproduction of the hydrographic structure compared to a throughﬂow with a smaller magnitude. A pure North Pacific source for the throughﬂow is also not capable of producing the salinity structure in the Banda Sea as suggested by previous studies and the required amount of salt to ﬁt the model salinity structure with observations in the Banda Sea is estimated to be 3.3x10‘3 kg. Most of the throughﬂow transport occurs in western boundary ﬂows and is largely topographically controlled. The separation of an upper and lower layer circulation pattern is controlled by the depth of the sill in Makassar Strait. Vertical excursions in the vicinity of this sill seen level of the in model results coincide upper salinity maximum with regions where are found. Seasonal large horizontal gradients at the upwelling and longer residence times due to weaker flows in the Banda Sea results in a more effective mixing of the already weakened salinity structure of the waters from Makassar Strait/Flores Sea. Net heat and freshwater flux estimates also reveal signiﬁcant departures at 200 up to 100 m between the Pacific inflow and Indian outflow, suggesting the considerable redistribution of heat and salt in the Indonesian Seas.

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46

Delgado, Dario. "Electrochemical properties of earth abundant catalysts for efficient water electrolysis." Thesis, Delgado, Dario (2016) Electrochemical properties of earth abundant catalysts for efficient water electrolysis. PhD thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/30718/.

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The hydrogen economy is attracting a great deal of attention from governments and major oil companies. Hydrogen is seen as a solution to the problems arising from the current unsustainable fossil fuel economy. Hydrogen generation can be done thermochemically, electrochemically and biochemically. Of all these options, hydrogen generation using renewable energy inputs to split water electrochemically into hydrogen and oxygen is potentially attractive on a commercial scale. Water electrolysis has two reactions happening simultaneously, the hydrogen and oxygen evolution reactions (i.e. HER and OER) from the cathode and anode respectively. Most of the relevant published work supports the use of platinum group metals for the HER and platinum group oxides for the OER. Platinum group materials are expensive thus a cheap substitute is needed. In this respect, lower cost substitutes (e.g., manganese dioxide, Raney cobalt and Raney nickel) were investigated possessing the following characteristics: (a) stable in the reaction environment; (b) environmentally friendly, (c) good catalytic activity and (d) earth abundant. The catalytic activity of materials in general can be enhanced by modifying their geometric and electronic factors. In the case of manganese dioxide (MnO2), the electronic factor has been modified by changing its crystalline structure and chemical composition through a range of additives. In the case of nickel and cobalt as raw materials, their geometric factor has been modified by increasing the surface areas with the use of Raney powders. The electrochemical characteristics of the above materials were investigated by subjecting them to linear voltammetry and electrochemical impedance spectroscopy. The materials were also characterized by physical techniques using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analyses. The obtained electrochemical results revealed that the best overpotentials found for Raney Ni and Raney Co in alkaline HER were -190 mV and -270 mV (i.e. n100 at 100 mA cm-2) respectively. The presence of Mo, Co and V as additives in the parent y type MnO2 substantially improved the catalytic activity towards acid and alkaline OER. In particular, for acid OER the Co/Mo bimetallic addition to y-MnO2 resulted in 305 mV (at n100) which is competitive to that of commercially available DSA® which is 341 mV (at n100). The physico-chemical characterization of the material before and after electrochemical experiments confirmed the stability in aqueous media. The effectiveness of the modified Watts bath for the deposition of Raney cobalt and Raney nickel, has been established through overpotential curves. The presence of oxide species lowers the efficiency of the electrode which increases the overpotential for the HER on Raney based electrodes. A porous Raney surface type enhances the available area for the hydrogen evolution reaction to occur which increases its energy efficiency (i.e. n100). Recommendations for further developmental work for such catalysts are made.

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47

Gibbs, Jennifer. "Solvent Properties of Ionic Liquids and the Alkane-Water Interface." Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/255153.

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Concerns over industrial emissions and nuclear waste have led to the need to study ways to sequester industrial gasses, and recycle nuclear fuel. Two projects were done to study solvent systems for these two problems using computational methods. Current methods for SO₂ sequestration are wasteful in that the gasses cannot be extracted from the solvent, and the solvent cannot be reused. One possible solution, which this work focuses on, is the use of an ionic liquid as a sequestration agent for the adsorption of SO₂. Separation technology for heavy elements has not changed for over 60 years and issues with radiation contamination and low efficiency lead to high solvent waste. Biphasic alkane-water extraction systems are a possible solution as they have been used for the extraction of heavy elements. This work focuses on characterizing the factors that control partitioning in biphasic systems which increase extraction efficiency.

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48

Bayer, Julia. "Soil water repellency : comparison between individual particles and bulk properties." Thesis, Swansea University, 2009. https://cronfa.swan.ac.uk/Record/cronfa42689.

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Two different methods for probing soil particle surfaces were tested and applied to particles from natural soils to examine soil water repellency arising from organic coatings on their surfaces. The applicability of laser scanning confocal microscopy to the characterisation of organic soil particle surface coatings was examined. Individual particle fluorescence showed a correlation with organic matter present in the corresponding soil, although not all organic material in soil fluoresces. This indicates that fluorescence could be used to probe soil particle surfaces. Other parameters such as the extent of coverage with fluorescent material, number of fluorescent areas and their size gave no consistent results, but seemed to be strongly dependent on sample origin and possibly factors such as the surface roughness of the particles. Another new method for investigating soil particle surfaces involved measurement of the height of a water lamella pulled up by an individual particle. Good agreement was found between lamella height and the contact angle of bulk soil materials of various but known water repellencies. Soil samples generally contained particles with a wide distribution of individual water repellencies. However, particles from water repellent soils showed more variation in lamella height than those from wettable soils, indicating a non-uniform distribution of hydrophobic surfaces within soil. The influence of pH on soil water repellency was examined by changing soil pH using gases rather than liquid reagents. Addition of base led to a decrease in water repellency confirming observations that soils of high pH are seldom water repellent. Using these methods it was not possible to unravel all the characteristics and effects of organic particle coatings on soil water repellency. However, the results indicate that these coatings, and their chemistry, may not be the only factor involved. Physical properties, such as surface roughness, may interact with the chemistry.

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SOARES, VIVIANE M. "Aspectos físicos e químicos do complexo de represas Paraibuna-Paraitinga, São Paulo." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10043.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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50

Dey, Fiona. "Study of the thickness of adsorbed water layers by atomic force microscopy." Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/844499/.

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The effect of ambient humidity and adsorbed water can be of critical importance in the processing of fine powders in air. Adsorbed water layers can influence the adhesive properties of the powder and may lead to difficulties in processing and handling. It has been shown, in the current work, that in ambient conditions the interaction between two solid surfaces is dominated by the force arising from the presence of adsorbed water layers. In the current work an atomic force microscopy technique has been developed to determine the separation distance at which two solid surfaces, i.e. the AFM cantilever tip and the sample surface, 'jump' into contact. From the separation distance the thickness of the adsorbed water layers on the cantilever tip and sample surface can be determined based on an analytical method originally developed by Forcada (1993), which considers the interacting forces which cause the 'jump' to contact. The adsorbed layer thickness, as a function of relative humidity, has been determined for silicon wafer, using the AFM technique. This localized adsorption isotherm has been compared with those published by other investigators, who have used different measurement techniques on large sample areas. The adsorption isotherm determined using the AFM technique reports adsorbed layer thicknesses that are significantly larger than those measured by other investigators. Adsorption isotherms have been determined, using the AFM technique, for three forms of a-lactose monohydrate, which is widely used throughout the pharmaceutical industry. It was observed that each form of lactose gave a different level of water adsorption. Laboratory grown crystals exhibited the greatest levels of moisture adsorption, while commercially produced milled a-lactose displayed lower levels of water adsorption. Differences in surface roughness may possibly explain the variation. For rough samples the probe tip makes contact with surface asperities and therefore does not detect the presence of condensed water in the surface valleys. It is also possible that surface contamination and process history may have influenced the levels of water adsorption but these are complex effects to quantify. Water adsorption isotherms were measured on bulk samples of classified lactose, to attempt to validate the AFM technique, developed in the current study. It can be observed that the adsorbed layer thicknesses determined using AFM are significantly larger than those inferred from bulk measurements. The AEM method provides layer thickness values which are approximately four times larger than what are believed to be the true values. This is seen for tests on silicon, aluminium and lactose surfaces. This discrepancy is thought to arise from the presence of the probe tip on the surface causing a local spatial inhomogeneity. The associated increase in surface potential will promote nucleation of water molecules, leading ultimately to capillary condensation.

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Dissertations / Theses on the topic 'Water properties'

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