Dissertations / Theses on the topic 'Liquid Media'
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1
Kulkarni, Prashant S. "Mixed Hydrophilic/Hydrophobic Fiber Media for Liquid-Liquid Coalescence." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1310686055.
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Stevar, M. S. P. "Dissolution dynamics of liquid/liquid binary mixtures in porous media." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/349974/.
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In this project has been undertaken an experimental study aimed at understanding the dissolution dynamics of binary mixtures within porous media. The porous medium can be roughly represented as a network of capillary tubes. This allowed for the initial research to be focused on understanding the dissolution dynamics of binary mixtures (i.e. glycerol/water, soybean oil/hexane, and isobutyric acid/water) within single capillary tubes. Further, the dissolution process was investigated within a 2D micromodel built as a network of capillary tubes. In the experiments with the capillary tubes, the dissolution (i.e. the interfacial mass transfer) could be isolated from the hydrodynamic motion while using glycerol/water and soybean oil/hexane binary mixtures. Despite the fact that these are fully miscible liquids, the interface could be observed for rather long time periods. In particular, two phase boundaries were observed moving from the ends into the middle section of the capillary tube with the speeds v∼D^1/3t^-2/3d^2(D, t and d are the coefficient of diffusion, time and diameter of the capillary tube, respectively). The boundaries slowly smeared but their smearing occurred very slow in comparison to their motion. The motion of the phase boundaries cannot be explained by the dependency of the diffusion coefficient on concentration, and could possibly be explained by the effect of barodiffusion. In addition, these solute/solvent boundaries were endowed with non-zero interfacial tension. This experimental study also revealed that the solvent penetration into the micromodel is diffusion-dominated for completely miscible binary mixtures. This is however non-Fickian diffusion with the dissolution rate dV/dt∼D^1/3t^-0.4 for almost the entire duration of the experiment (V is the volume occupied by the solvent, D is the diffusion coefficient and t is time). For the IBA/water mixture the experiments performed at undercritical temperatures revealed that the diffusive mass transport was negligible despite the mixture being out of its thermodynamic equilibrium. Despite a seeming simplicity of the experiments, to the author’s best knowledge, there is no theory that could correctly describe the observed diffusional penetration of a solvent into a solute-filled capillary tube and hence, into a more complex porous volume.
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O'Toole, Sarah. "Electrochemical studies in ionic liquid media." Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479403.
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Marley, Eunan. "Electrochemical reactivity in ionic liquid media." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675853.
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In our work, a number of reaction processes were investigated, using ionic liquids (ILs), or ionic liquid-based salts, as either the solvent or reactant. In chapter 3, the active form of TEMPO, the oxoammonium cation (T+), was used to synthesise T+ -bis(trifluoromethylsulfonyl)imide (NTf2) and T+trifluoromethanesulfonate (triflate) salts. These salts were used to investigate the mediated oxidation of primary alcohols. It was found that the oxidation process proceeded more rapidly for methanol than for the other two alcohols investigated. A significant drop in T+ current occurred when only base was added to the cell, with a multistep reaction process likely to be involved. The use of a solid DOWEX resin as base was also briefly investigated. In chapter 4, the electrocarboxylation of a number of benzophenone derivatives was investigated. For all investigated compounds, the carboxylation process proceeded via a ECE / DISPl mechanism. It has been found that the variation of the carboxylation reaction kinetics can be predicted based on the nature of the functional groups present on the benzene rings. Electron donating groups increased the rate of carboxylation, while electron withdrawing groups decreased the rate of carboxylation. The electrocarboxylation in I -butyl-lmethylpyrrolidinium bis-(trifluoromethane sulfonyl)imide [Bmpy][NTfz] were 2 orders of magnitude slower than those reported in DMF. In chapter 5, CO2 reduction in [Bmpy][NTfz] was briefly investigated at a number of electrode types (glassy carbon, platinum, palladium, gold, indium) using cyclic voltammetry. CO2 reduction was observed at all 5 electrodes, where it was found that Au and especially In act as electrocatalysts. The mediated reduction of COz in [Bmpy] [NTfz] was then attempted using methyl benzoate and dimethyl phthalate. Investigation of the electrochemistry of the two compounds in IL suggests that ion pairing causes an increase in the rate of dimerization over carboxylation, preventing the ester from acting as a redox mediator.
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Brown, Jacob Leslie. "Vapour-liquid equilibria within nanoporous media." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277690.
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This thesis is dedicated to the exploration of fluid phases confined in nanoporous materials using Nuclear Magnetic Resonance (NMR) techniques, with an aim to benefit catalysis research. Included in this report are studies of pure fluids and their mixtures, confined in titania and silica catalyst supports. These investigations are conducted at industrially-relevant, high-temperature (≥ 180 °C) and high-pressure conditions (up to 13 bar), made possible by a pilot-scale chemical reactor unit, designed to operate inside the strong magnetic fields of an NMR spectrometer. NMR spectroscopy, relaxation and pulsed field gradient (PFG) diffusion experiments were performed on each of the systems discussed in this report. Cyclohexane was initially studied inside a porous titania catalyst support at 188 °C and various pressures up to 13 bar. The adsorption and desorption processes of the cyclohexane were observed, revealing a number of previously unobserved phenomena. In addition to an overall, averaged diffusion coefficient, a slow diffusion coefficient was observed within the PFG NMR data attributable to surface diffusive processes occurring within the material. Additionally, T1 relaxation studies were found to provide experimental evidence for the differing configurations of adsorbed layers on the adsorption and desorption branch of the isotherm. Cyclohexane was subsequently studied alongside fluorobenzene in a series of silica catalyst supports of 6 nm, 10 nm and 20 nm pore size. In doing this, it was hoped that the multiple phenomena observed in the titania experiments might be deconvoluted, allowing a greater level of insight. The diffusivities of the fluids were found to differ significantly between the materials, and greater evidence was found of the slow-diffusing surface phase in each of the materials. Additionally, concentrations of cyclohexane and fluorobenzene in the gas and adsorbed layers inside the pore space were calculated via the results of the PFG NMR experiments, providing a map of confined phase behaviour. Competitive adsorption effects were found to become more significant, the smaller the pore size of the material. The results of the cyclohexane and fluorobenzene in silica studies were modelled, using approaches available in the literature, which were found to give varying levels of prediction. The data set acquired in this thesis was found to provide a useful standard, against which current and future models of confined phase behaviour might be verified.
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Ipek, Bahar. "Photocatalytic Carbon Dioxide Reduction In Liquid Media." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613183/index.pdf.
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The aim of this study is to investigate and reveal challenges in
photocatalytic CO2 reduction tests performed in liquid media. Effect of test conditions in photocatalytic studies are often underestimated with an assumption of negligible mass transfer limitations in observed rate results. In this study, effect of mass transfer limitations in liquid phase photocatalytic tests was revealed with stirring rate and gas hold-up time experiments performed with Pt/TiO2 and Cu/TiO2 catalysts. In addition, apparent activation energies of 12 and 19.5 kJ/mol found with Pt/TiO2 and Cu/TiO2 catalysts respectively indicate diffusion
limitations which favor back oxidation reactions resulting in low reduction yields.
Photocatalytic CO2 reduction reaction is named as Artificial Photosynthesis even though present artificial system does not have sophisticated transport and membrane systems which natural systems have. Similarities and differences between artificial and natural photosynthesis are studied in order to present ideas to improve present photocatalytic rates.
Kinetic and microkinetic modeling of catalytic methanol production from CO2 hydrogenation on Cu surfaces were performed in order to have an idea about kinetic limitations at photocatalytic systems. Calculations were performed at
temperatures and pressures at which photocatalytic studies are conducted. The results indicated that water has an inhibitory effect on methanol formation rates and higher pressures could be implemented in photocatalytic systems for higher rates. Another implication drawn from degree of rate control calculations is that H formation step plays an important role underlying the importance of water splitting in CO2 reduction reactions.
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Shin, Youn-Ok 1971. "Vapor and liquid equilibria in porous media." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21323.
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The alteration of the vapor and liquid equilibrium (VLE) of volatile organic mixtures by using porous media at the liquid-vapor interface was studied. Kelvin, assuming ideal behavior of fluids, first introduced the vapor pressure of liquid over a meniscus as a function of its surface tension and the radius of the curvature. A thermodynamic model (SSmod model) predicting the VLE of non-ideal organic mixtures in porous media was developed as a function of pore sizes based on the pressure equations available in literature. The model was used to predict the VLE of two aqueous alcohol solutions, ethanol-water and propanol-water, and two binary alcohol solutions, methanol-isopropanol and ethanol-octane. Experiments were conducted using sintered metal and fritted glass plates as porous media and compared with the model predictions. The model predictions for the actual pore diameters tested showed good agreement with the experimental results.
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Shin, Youn-Ok. "Vapor and liquid equilibria in porous media." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0022/MQ50659.pdf.
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Russo, Ann. "Immiscible Liquid Dissolution in Heterogeneous Porous Media." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194522.
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Immiscible liquids, including chlorinated solvents, have proven to be a lasting source of subsurface contamination at many hazardous waste sites. Continued improvement of site characterization and determination of applicable remediation technologies can be achieved by further understanding of the transport and fate of these contaminants. The transport and fate of trichloroethene (TCE) was investigated through miscible displacement and dissolution experiments. Miscible displacement experiments were conducted using homogeneously packed columns with several porous media encompassing a range of particle size distributions. Immiscible liquid dissolution was investigated using homogeneously packed columns containing a residual saturation of trichloroethene. The same porous media were used for immiscible liquid dissolution experiments. Mathematical modeling of miscible displacement and dissolution experiments was conducted using a one-dimensional single region or multi-region model. Imaging of immiscible liquid dissolution was also conducted, using Synchrotron X-ray Microtomography imaging at Argonne National Laboratory, Argonne, IL. Dissolution experiments exhibited nonideal dissolution behavior that was apparent in observed effluent data and in collected imaging data. Nonideal behavior was manifested as secondary regions of relatively constant aqueous concentrations occurring for a number of pore volumes. This behavior was observed to increase in magnitude as particle size distribution of the porous media increased. During imaging, immiscible liquid blobs were observed to dissolve throughout the column during dissolution. This behavior is also indicative of nonideal dissolution, as it would be expected that dissolution would first occur for the blobs nearest the inlet and then proceed upward through the column as dissolution progressed. In many cases, a multi-region modeling approach was necessary to successfully represent the nonideal behavior observed. Comparisons were made between the natural porous media used for this research and a well-sorted sand. Nonideal dissolution was not observed in the well-sorted sand.
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Thompson, Linda Helen. "Reactions in liquid sulphur dioxide based media." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335469.
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Kay, Nicola Julie. "Single molecule electronics in ionic liquid media." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/6733/.
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The field of single molecule electronics, where the charge transport properties of a variety of single molecular systems are investigated, has vastly increased in popularity over the last decade. This thesis in particular explores the single molecule conductance and electron transfer over a range of molecules in a room temperature ionic liquid medium. Prior to the work contained in this thesis, no conductance measurements of a single molecule had been recorded in a room temperature ionic liquid medium, to the best of our knowledge. Due to the novelty of room temperature ionic liquids in this field, it was decided that alkanedithiols would be an ideal starting point, largely due to their simplicity and reputation as a model system in single molecule electronics. Ionic liquids have several notable advantages as a medium in such measurements and the aim of the research contained in this thesis is first to show that ionic liquids are indeed a viable medium and secondly, to demonstrate their advantages over more widely used, conventional aqueous or organic media. The redox active molecular wire pyrrolo-tetrathiafulvalene is a particular molecule which would highlight the benefits of an ionic liquid medium, as it has a redox transition which is outside of the potential window available to aqueous electrolytes. Single molecule conductance measurements were obtained using a scanning tunnelling microscope (STM), in particular, the current-distance I(s) technique, and for alkanedithiols also the STM break junction technique. The electrochemistry of pyrrolo-tetrathiafulvalene was investigated using cyclic voltammetry and a monolayer of pyrrolo-tetrathiafulvalene was characterised using polarisation modulation infrared reflection absorption spectroscopy (PM-IRRAS).
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Guo, Tianle. "Effects of buoyancy forces on miscible liquid-liquid displacements in porous media." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6825.
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The effects of gravity forces on the miscible displacement of one fluid (aqueous glycerol solution) by another fluid (pure water) in a vertical consolidated porous medium have been investigated. A set of horizontal displacement experiments was performed for comparison with two sets of vertical-upward and vertical-downward displacements. It was found that gravitational forces (i.e. buoyancy forces) can be an important factor in determining the displacement pattern where fluids having different densities and different flowrates are involved. In a given porous medium system, the principal variables which affect the displacement efficiency of oil (or any other miscible liquid) by water are the viscosity ratio, density difference, and displacement flowrate. Increasing the viscosity ratio will decrease the oil recovery; however, when the viscosity ratio is close to unity, good oil recovery will be obtained. The injection flowrate is also critical. At low injection flowrates, the effects of gravity become relatively more important. At high flowrates, gravity forces have less effect on the displacement efficiency. In vertical-upward displacements, buoyancy forces play a negative role since they tend to promote viscous fingering and consequently lower the oil recovery (when $\rm \rho\sb{oil}>\rho\sb{water}$). On the other hand, in vertical-downward displacements, buoyancy forces tend to stabilize the displacement process, and high oil recoveries can be obtained. Comparing the horizontal displacement patterns with those of the two vertical displacements, it was found that buoyancy forces can exert very significant effects on fingering phenomena.
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Meyer, William Vernon. "Volume and interface studies of complex liquid media." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2002. http://dare.uva.nl/document/66692.
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Dixit, Manesh A. "Liquid crystal and hydrophilic gel media for iontophoresis /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488186329504287.
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Klossek, Michael Lorenz [Verfasser], and Werner [Akademischer Betreuer] Kunz. "Nanostructured liquids, colloids and environmentally acceptable liquid media / Michael Lorenz Klossek. Betreuer: Werner Kunz." Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1033688509/34.
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Tsai, Chang-Ching. "Propagation Effect in Inhomogeneous Media, Including Media with Light-Induced and Fixed Gratings." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4255.
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Optical waves propagation in various types of volume gratings, materials with constant impendence and optical fibers are studied. Instability of cross–phase modulation and of Energy transfer via GRON-type (Grating-type Orientational Nonlinearity in Liquid Crystal) Stimulated Scattering is numerically observed. Two diffractive optical elements made of volume gratings are suggested and analyzed. A transmission hologram based on the analogy with Stimulated Raman Adiabatic Passage (STIRAP) in nonlinear optics is proposed. This transmission hologram demonstrates high diffraction efficiency and low sensitivity to polarization and hologram strength. The other is a reflection hologram with two crossed-gratings. It features good angular selectivity in comparison with the poor angular selectivity of conventional Bragg grating mirror. This defense also contains the approximation of Maxwell equations for the description of depolarized light sources and polarization-insensitive detectors. A scalar wave equation, Z-Helmholtz equation, is proposed and discussed in the approximation of constant impedance media. As examples, this equation successfully describes a) Fresnel transmission coefficient, and b) Goose-Hanschen shift in total internal reflection, for depolarized incident light and, at the same time, polarization-insensitive detectors. Evolution of polarization during light propagation in an inhomogeneous locally isotropic medium, and also in a single-mode fiber is described by Rytov's non-rotation equation. With arbitrary chosen real unit vector, the complete description of polarization change can be described in a single rotation angle obtained from the integral of rotation rate. Based on introduction of this reference frame, a device is suggested as rigid body's rotation sensor due to polarization change in a twisted fiber.Ph.D.
Other
Optics and Photonics
Optics
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Lifsey, Karen Marie. "Liquid crystal polymers : a unique class of separation media." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365163.
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West, Pamela Jayne. "Electrochemistry and corrosion studies in nitrogen oxide liquid media." Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357065.
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Damronglerd, Piyasak Zhang Yuwen. "Infiltration and solid-liquid phase change in porous media." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6143.
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Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 17, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Yuwen Zhang. Vita. Includes bibliographical references.
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Tsuchiya, Katsumi. "Wake dynamics behind a single gas bubble in a liquid and liquid-solid fluidized media /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu148733076121663.
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Al-Saffar, H. B. S. "Fluid flow through porous media : liquid distribution and mass transfer." Thesis, Swansea University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635715.
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This work presents the results of an experimental study of liquid distribution with counter-current gas flow and without gas flow, carried out in a 0.3m diameter and 1.5m long perspex column packed randomly with 1" plastic Pall rings, 1" plastic Intalox saddles, No.25 Intalox Metal Tower Packing(IMTP) and No.1 metal Nutter rings, in separate experimental sets. The measurements were carried out using concentric annular collectors, in order to measure the distribution of liquid and to distribute the gas uniformly across the bottom of the column. The column was operated with gas flowrates varying over the range of 0 to 1 kg/m2.sec, and liquid flowrates varying over the range of 40 to 80 1/min. Packing height was increased by adding successive layers of packing, while the ratio of the flow supplied to the bulk and wall regions was varied throughout the experiments. The experimental results were analyzed and compared to a theoretical model developed by Gunn(1978) and extended in 1991. Two regions of packing of different permeabilities may be distinguished, the bulk region and an annular region of packing adjacent to the wall and of higher permeability. The wall region was confined to the order of one particle diameter while the remaining cross-section of the column was accounted as the bulk region. The separation of volumetric mass transfer coefficients in packed columns into mass transfer coefficients and specific surface area, has been attempted using the available data on mass transfer presented by various investigators. One aim of this work is to provide a generalized correlation for mass transfer coefficients and interfacial area that characterized the mass transfer performance of various packings that may be used for designing or scaling up columns or reactors.
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Saharudin, Mohd. "Mechanical properties of polyester nano-composites exposed to liquid media." Thesis, Northumbria University, 2017. http://nrl.northumbria.ac.uk/36179/.
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Halloysite nanotubes (HNTs) offer excellent improvements in wide range of physical and engineering properties at low filler content. Due to their outstanding properties such as large aspect ratio, high surface area, flame retardant and good optical clarity, HNTs polymer nanocomposites are widely used in automotive, coating, packaging and medical devices. The results showed that the incorporation of halloysite nanotubes (HNTs) into polyester significantly improved dynamic mechanical properties of the nanocomposites including the glass transition temperature (Tg), storage moduli, microhardness, tensile properties, flexural properties and impact toughness. The mechanical properties of polyester-based nanocomposites were degraded after water-methanol exposure. The maximum microhardness, tensile, flexural and impact toughness values were measured at 1 wt% of HNTs reinforcement and the results also showed that HNTs improved the liquid barrier properties of polymers due to an increase in the tortuosity path. Several deterioration effects are likely to take place concurrently after seawater exposure. Plasticization reduced the mechanical properties of the nanocomposites and microorganisms such as microbes entered through microvoids to further increase the deterioration in mechanical properties of the nanocomposites. Microbes can cause chemical degradation and the breakage of hydrocarbons using seawater molecules. Nanocomposite biodegradation is highly undesirable for material integrity as these are mostly used in structural designs of marine applications. Structural damage may result in premature weakening which is often translated into system failure and enormous economic losses. The influence of short-term water absorption on the mechanical properties of HNTs-multi layer graphene-reinforced polyester hybrid nanocomposites was also investigated. After short-term water exposure, the maximum microhardness, tensile, flexural and impact toughness values were observed in case of polyester-multi-layer graphene (MLG) nanocomposites. It was also found that synergistic effects were not effective at a concentration of 0.1 wt % in producing considerable improvement in the mechanical properties of the hybrid nanocomposites.
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Liu, Jiayi. "Functionalized Octatetrayne as Novel Carbon Media for Capillary Liquid Chromatography." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1428922624.
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Palakurthi, Nikhil Kumar. "Direct Numerical Simulation of Liquid Transport Through Fibrous Porous Media." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881191.
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Whelan, Michael P. "Dissolution of non-aqueous phase liquid pools in saturated porous media." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/20140.
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Powell, David Anthony, and davidanthonypowell@gmail com. "Modelling of Layered Surface AcousticWave Resonators for Liquid Media Sensing Applications." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070122.164018.
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In this thesis a model is developed to characterise the behaviour of layered SAW 2- port resonator sensors operating in liquid media. In the critical review of literature, it is found that methods based on the periodic Green's function combined with the COM model are best suited to this task. However, an important deficiency of this approach is the lack of a good model for electrodes buried within layered media. This deficiency is resolved in this thesis by the formulation of a periodic matrix eigen-operator, using a phase-shifted Fourier series representation. This model is then utilised in the study of resonator behaviour as a function of guiding layer thickness, including the mass sensitivity. Based on this modelling work, a SAW resonator structure is designed, and its frequency response is found to be in generally good agreement with theoretical predictions. The mass sensitivity of this device is then analysed using both theoretical and experimental means. In contrast to the sensitivity analyses found in the literature, sensitivity variation across the device surface is considered in this work. For the resonator structure it is found that sensitivity is greatest at the device centre, with the ends of the device making negligible contribution to the complete device response. The result is that the sensitive material may be deposited only in a small region in the centre of the device, with minimal reduction in device response.
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Nikolopoulos, Panagiotis. "Mass transfer in non-aqueous phase liquid contaminated heterogeneous porous media." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611535.
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Shittu, Akinwale A. "Catalytic Conversion of Hemicellulosic Sugars into Furfural in Ionic Liquid Media." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1290137873.
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Pastore, Andrea. "Syngas production from heavy liquid fuel reforming in inert porous media." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/237704.
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In the effort to introduce fuel cell technology in the field of decentralized and mobile power generators, a hydrocarbon reformer to syngas seems to be the way for the market uptake. In this thesis, a potential technology is developed and investigated, in order to convert commercial liquid fuel (diesel, kerosene and biodiesel) to syngas. The fundamental concept is to oxidise the fuel in a oxygen depleted environment, obtaining hydrogen and carbon monoxide as main products of the reaction. In order to extend the flammability limit of hydrocarbon/air mixtures, the rich combustion experiments have been carried out in a two-layer porous medium combustor, which stabilises a flame at the matrix interface and recirculates the enthalpy of the hot products in order to enhance the reaction rates at ultra-rich equivalence ratio. This thesis demonstrates the feasibility of the concept, by exploring characteristic parameters for a compact, reliable and cost effective device. Specifically, a range of equivalence ratios, thermal loads and porous materials have been examined. n-heptane was successfully reformed up to an equivalence ratio of 3, reaching a conversion efficiency (based on the lower heating value of H2 and CO over the fuel input) up to 75% for a packed bed of alumina beads. Thermal loads from P=2 to 12 kW at phi=2.0 demonstrated that heat losses can be reduced to 10%.Similarly, diesel, kerosene and bio-diesel were reformed to syngas in a Zirconia foam burner with conversion efficiency over 60%. The effect of different burners, thermal loads and equivalence ratios have also been assessed for these commercial fuels, leading to equivalent conclusions. A preliminary attempt to reduce the content of CO and hydrocarbons in the reformate has been also performed using commercial steam reforming and water-gas shift reaction catalysts, obtaining encouraging results. Finally, soot emission has been assessed, demonstrating particle formation for all the fuels above phi=2.0, with biodiesel showingthe lowest soot formation tendency among all the fuels tested.
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Guo, Tianle. "Experimental and theoretical studies of the effects of buoyancy forces on liquid/liquid displacement processes in porous media." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq26121.pdf.
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Matthews, Glenn Ian, and gimatthews@ieee org. "Investigation of Flexural Plate Wave Devices for Sensing Applications in Liquid Media." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090219.120815.
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In this thesis, the author proposes and presents a novel simulation technique for the analysis of multilayered Flexural Plate Wave (FPW) devices based on the convergence of the Finite Element method (FEM) with classical Surface Acoustic Wave (SAW) analysis techniques and related procedures. Excellent agreement has been obtained between the author's approach and other more conventional modelling techniques. Utilisation of the FEM allows the performance characteristics of a FPW structure to be critically investigated and refined before undertaking the costly task of fabrication. Based on a series of guidelines developed by the author, it is believed the proposed technique can also be applied to other acoustic wave devices. The modelling process developed is quite unique as it is independent of the problem geometry as verified by both two and three dimensional simulations. A critical review of FEM simulation parameters is presented and their effect on the frequency domain response of a FPW transducer given. The technique is also capable of simultaneously modelling various second-order effects, such as triple transit, diffraction and electromagnetic feedthrough, which often requires the application of several different analysis methodologies. To verify the results obtained by the author's novel approach, several commonly used numerical techniques are discussed and their limitations investigated. The author initially considers the Transmission Matrix method, where it is shown that an inherent numerical instability prevents solution convergence when applied to large frequency-thickness products and complex material properties which are characteristic of liquids. In addition the Stiffness Matrix method is investigated, which is shown to be unconditionally stable. Based on this technique, particle displacement profiles and mass sensitivity are presented for multilayered FPW structures and compared against simpler single layer devices commonly quoted in literature. Significant differences are found in mass sensitivity between single layer and multilayered structures. Frequency response characteristics of a FPW device are then explored via a spectral domain Green's function, which serves as a further verification technique of the author's novel analysi s procedure. Modifications to the spectral domain Green's function are discussed and implemented due to the change in solution geometry from SAW to FPW structures. Using the developed techniques, an analysis is undertaken on the applicability of FPW devices for sensing applications in liquid media. Additions are made to both the Stiffness Matrix method and FEM to allow these techniques to accurately incorporate the influence of a liquid layer. The FEM based approach is then applied to obtain the frequency domain characteristics of a liquid loaded FPW structure, where promising results have been obtained. Displacement profiles are considered in liquid media, where it is shown that a tightly coupled Scholte wave exists that is deemed responsible for most reported liquid sensing results. The author concludes the theoretical analysis with an in-depth analysis of a FPW device when applied to density, viscosity and mass sensing applications in liquid media. It is shown that a single FPW device is potentially capable of discriminating between density and viscosity effects, which is typically a task that requires a complex and costly sensor array.
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Johns, M. L. "MRI studies and modelling of two phase-liquid systems in porous media." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605617.
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Hydrocarbon ganglia, trapped in the pore space of a ballotini packing by capillary forces, were selectively imaged using MRI. The geometric characteristics of these ganglia were monitored as they dissolved into a surrounding mobile aqueous phase. In particular the surface area of the ganglia was quantified during the course of dissolution. This was then included into a one-dimensional advection-dispersion model of the ganglia dissolution process, which contained only one free parameter, the mass transfer coefficient. The model predicted the experimental data reasonably well, but tended to over-predict dissolution after long time periods. Heterogeneity in pore-scale flow was identified as an explanation for this. The one-dimensional model was extended to systems composed of smaller packing material where imaging of the ganglia was no longer possible. The surface area of the ganglia was quantified by monitoring the diffusion of the hydrocarbon molecules inside the ganglia using pulsed field gradient nuclear magnetic resonance. An alternative three-dimensional model of the dissolution process was developed based on the used of cellular automata. Three-dimensional velocity images of the mobile aqueous phase surrounding the dissolving ganglia were acquired using MRI, and included into this modelling approach. Ganglia formation following an imbibition process, in which water displaced the hydrocarbon from the pore space of the packing, was also investigated using MRI. the results of this experimental investigation were compared with those produced by application of an invasion percolation model to a pore network representation of the pore space. Reasonable agreement between the experimental data and this modelling approach was produced. This pore network was generated using a pore thinning algorithm which segments the pore space into individual pores. An evaluation of this algorithm using different packing structures was also performed.
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Ardelean, Ioan, German Farrher, Carlos Mattea, and Rainer Kimmich. "From "fast" to "slow" liquid-vapor exchange in partially filled porous media." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-194922.
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Richardson, David Jeremy. "Enhanced mass transport in liquid-saturated porous media due to surface shear." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/27112.
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The principal aim of this work was the development of a novel conductivity probe for measuring solids concentrations in slurries. The relevance of the thesis to this probe is that it requires rapid transport of aqueous electrolyte through a porous disc to an internal conductivity cell.
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Nguyen, Khac Long. "Multiscale analysis of transport in porous media." Thesis, Aix-Marseille, 2019. http://theses.univ-amu.fr.lama.univ-amu.fr/190522_NGUYEN_156sqbpnr595zlxet195ycj854nvqyn_TH.pdf.
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La corrélation entre les propriétés structurales des matériaux et les propriétés de transport d’un fluide à travers les matériaux poreux intervient dans de nombreux procédés en physique, chimie, géologie et ingénierie. Les propriétés telles que la porosité et la distribution de taille de pore ne reflètent pas la complexité du réseau poreux qui consiste en un réseau de pores interconnectés irrégulier et de différentes sections. La complexité est décrite par un paramètre appelé la tortuosité. La tortuosité est déterminé par des mesures électriques ou par chromatographie liquide. En chromatographie liquide la tortuosité intraparticulaire est calculée à partir du coefficient de diffusion intraparticulaire de polystyrènes déterminé à partir de l’élargissement des pics obtenus en mode dynamique et en mode statique en conditions non-adsorbantes avec le solvant tétrahydrofurane (THF). En mode dynamique, dans l’équation de van Deemter, le terme constant dépend de la diffusion d’eddy et de la polydispersité des polystyrènes. La silice poreuse Si100 présente une distribution de taille des pores assez large ce qui entraîne l’élargissement des pics chromatographiques. Le transport de polystyrènes à travers les silices en conditions adsorbantes a également été étudié en modifiant le solvant. En conditions adsorbantes, avec un mélange de THF et d’heptane, pour un polymère de taille donné, plusieurs pics sont obtenus en raison de la polydispersité du polystyrène. L’adsorption augmente avec la masse molaire du polystyrène. La diffusion de surface diminue lorsque le facteur de rétention augmenteThe correlation of the structural parameters with the transfer properties of a fluid through a porous media is a significant subject in physics, chemistry, geology, and engineering. The architectural parameters such as porosity and pore size distribution do not describe the complexity of most porous organizations consisting of labyrinths of interconnected pores with random shapes and cross-sections. This complexity is described by a parameter called tortuosity. The apparent total and particle tortuosities are determined by electrical measurements or the analysis of the peak shape of chromatographic probes. In the latter case, the particle tortuosity of silica is calculated from effective intraparticle diffusion coefficient determined by modelling the chromatographic peak broadening of polystyrenes obtained either in dynamic or in static conditions under non-adsorbing conditions by using the solvent tetrahydrofuran (THF). In dynamic conditions, the constant term in the van Deemter equation is a combined contribution of eddy diffusion and polydispersity of the polystyrenes and depends on the size of the molecule. The broad pore size distribution of totally porous silica contributes also to the spreading of the peak. The transport of polystyrenes through silica columns has also been studied in adsorbing conditions by changing the solvent. With the mixture of n-Heptane and THF, one obtains many peaks for a polystyrene sample due to the polydispersity of the polystyrene. In fact, the adsorption increases with the molecular weight of the polystyrenes. The surface diffusion of polystyrene decreases with an increase in the retention factor
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MacNeil, John Michael Larratt. "Solitary waves in focussing and defocussing nonlinear, nonlocal optical media." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20951.
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Nonlinear, nonlocal optical media has emerged as an ideal setting for experimentally observing and studying spatial optical solitary waves which otherwise cannot occur in Kerr media. Of particular interest is the eventual application to all-optical circuits. However, there is considerable work left to do on the theoretical end before this is a possibility. In this thesis we consider three problems. The first is how to solve the governing equations for optical beam propagation in the particular medium of the nematic liquid crystal (NLC), which is used as a prototypical example, exactly and approximately. In this respect we provide the first known, explicit solutions to the model as well as a comprehensive assessment on how to use variational, or modulation theory, in this context. This leads to the discovery of a novel form of bistability in the system, which shows there are two stable solitary wave solutions for a fixed power or L2 norm. We then consider how to approximate solutions for optical solitary waves propagating in a more general class of nonlocal nonlinear media using asymptotic methods. This is a long open problem and is resolved in the form of a simple to implement method with excellent accuracy and general applicability to previously intractable models. We conclude with the discovery and characterization of an instability mechanism in a coupled, defocussing nonlinear Schrodinger system. We show there is no stable, coupled, localized solution. This result is compared with the more well-studied bright solitary wave system and physical and mathematical explanations are offered.
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White, Tom 1971. "Introducing liquid haptics in high bandwidth human computer interfaces." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/62938.
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Lacassagne, Tom. "Oscillating grid turbulence and its influence on gas liquid mass transfer and mixing in non-Newtonian media." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI103/document.
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L’étude du transfert de masse turbulent aux interfaces gaz-liquide est d’un grand intérêt dans de nombreuses applications environnementales et industrielles. Bien que ce problème soit étudié depuis de nombreuses années, sa compréhension n’est pas encore suffisante pour la création de modèles de transfert de masse réalistes (de type RANS ou LES sous maille), en particulier en présence d’une phase liquide à rhéologie complexe. Ce travail expérimental a pour but l’étude des aspects fondamentaux du transfert de masse turbulent à une interface plane horizontale entre du dioxyde de carbone gazeux et une phase liquide newtonienne ou non, agitée par une turbulence homogène quasi isotrope. Les milieux liquides non newtoniens étudiés sont des solutions aqueuses d’un polymère dilué à des concentrations variables et aux propriétés viscoélastiques et rhéofluidifiantes. Deux méthodes de mesure optiques permettant l’obtention du champ de vitesse de la phase liquide (SPIV) et de concentration du gaz dissout (I-PLIF) sont couplées tout en maintenant une haute résolution spatiale, afin de déduire les statistiques de vitesse et de concentration couplées dans les premiers millimètres sous la surface. Une nouvelle version de I-PLIF est développée pour les mesures en proche surface. Elle peut également s’appliquer dans différentes études de transfert de masse. La turbulence de fond est générée par un dispositif de grille oscillante. Les mécanismes de production et les caractéristiques de la turbulence sont étudiés. L’importance de la composante oscillante de la turbulence est discutée, et un phénomène d’amplification de l’écoulement moyen est mis en évidence. Les mécanismes du transfert de masse turbulent à l’interface sont finalement observés pour l’eau et une solution de polymère dilué à faible concentration. L’analyse conditionnelle des flux de masse turbulent permet de mettre en évidence les évènements contribuant au transfert de masse et de discuter de leur impact relatif sur le transfert totalThe study of turbulence induced mass transfer at the interface between a gas and a liquid is of great interest in many environmental phenomena and industrial processes. Even though this issue has already been studied for several decades, its understanding is still not good enough to create realistic models (RANS or sub-grid LES), especially when considering a liquid phase with a complex rheology. This experimental work aims at studying fundamental aspects of turbulent mass transfer at a flat interface between carbon dioxide and a Newtonian or non-Newtonian liquid, stirred by homogeneous and quasi isotropic turbulence. Non-Newtonian fluids studied are aqueous solutions of a model polymer, Xanthan gum (XG), at various concentrations, showing viscoelastic and shear-thinning properties. Optical techniques for the acquisition of the liquid phase velocity field (Stereoscopic Particle Image Velocimetry, SPIV) and dissolved gas concentration field (Inhibited Planar Laser Induced Fluorescence, I-PLIF) are for the first time coupled, keeping a high spatial resolution, to access velocity and concentration statistics in the first few millimetres under the interface. A new version of I-PLIF is developed. It is designed to be more efficient for near surface measurements, but its use can be generalized to other single or multiphase mass transfer situations. Bottom shear turbulence in the liquid phase is generated by an oscillating grid apparatus. The mechanisms of turbulence production and the characteristics of oscillating grid turbulence (OGT) are studied. The importance of the oscillatory component of turbulence is discussed. A mean flow enhancement effect upon polymer addition is evidenced. The mechanisms of turbulent mass transfer at a flat interface are finally observed in water and low concentration polymer solutions. A conditional analysis of turbulent mass fluxes allows to distinguish the type of events contributing to mass transfer and discuss their respective impact in water and polymer solutions
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Carroll, Kenneth Cooper. "Characterization, Dissolution, and Enhanced Solubilization of Multicomponent Nonaqueous Phase Liquid in Porous Media." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195399.
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Multicomponent nonaqueous phase liquids (NAPL) contaminating the subsurface can significantly inhibit remediation. One method of enhancing the rate of remediation of NAPL constituents, compared to pump-and-treat, involves source zone treatment with enhanced solubilization agents (ESAs) including cyclodextrins. Equilibrium cyclodextrin enhanced solubilization of simple 1, 2, and 3 component NAPL mixtures was examined to evaluate the applicability of Raoult's Law. The results suggest that Raoult's Law may be used to estimate equilibrium and early-time dynamic concentrations in contact with ideal NAPL mixtures, and Raoult's Law may be used to estimate cyclodextrin enhanced groundwater concentrations for ideal NAPL mixtures. Solubility enhancement of NAPL compounds was dependent on the cyclodextrin concentration and independent of NAPL composition. Column experiments and numerical modeling were used to evaluate the dissolution behavior of the NAPL mixtures in water and a cyclodextrin solution to estimate mass transfer rates. The aqueous multicomponent dissolution followed Raoult's Law, and the model-estimated lumped rate coefficients were independent of the NAPL composition. Addition of the cyclodextrin enhanced the dissolution and removal of compounds from residual NAPL due to an increase in the driving force (i.e. concentration gradient) and the mass transfer coefficient. The model results suggest that Raoult's Law is applicable for ideal NAPL mixture dissolution in water, but potential nonideality was observed and caused the model simulation to deviate from the dissolution behavior for NAPL mixture cyclodextrin experiments. The cyclodextrin dissolution experiments were less rate-limited than aqueous dissolution, and the mass transfer coefficients were quantified with the model. The results of the model suggest that NAPL mixture nonideality and intra-NAPL diffusion may also impact enhanced dissolution behavior. Additionally, the importance of NAPL mixture characterization was illustrated by evaluation of a mixture of PCE (tetrachloroethene) and diesel fuel collected from a site in Tucson, Arizona. A sample from the site was used to create mixtures with increasing PCE in the NAPL. Chemical evaluation of the complex NAPL was conducted, and physical property and phase partitioning testing was performed, which demonstrated the effect of NAPL composition on its distribution, interphase mass transfer, and potential mobilization.
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Bai, Guiyun 1964. "Biosurfactant-enhanced nonaqueous phase liquid (NAPL) removal and bacterial transport in porous media." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282451.
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The well documented ineffectiveness of traditional pump-and-treat technology on the cleanup of non aqueous phase liquid (NAPL) contaminated sites has incurred an intensive research activities in improving the efficiency of NAPL removal from subsurface. Surfactant enhanced subsurface remediation has been proposed as one such option. In this dissertation, a series laboratory experiments were conducted to investigate the potential application of a microbially produced surfactant (biosurfactant) on NAPL removal and the effect on bacteria transport. Monorhamnolipid biosurfactant, produced by Pseudomonas aeruginosa ATCC 9027, was used in all the studies. Hexadecane was used as model NAPL to represent petroleum based products which are common NAPLs detected in contaminated sites. Results showed that rhamnolipid biosurfactant is effective in removing residual hexadecane from sandy soil. In the surfactant concentration tested in this study (40 to 1500 mg/L), mobilization of hexadecane is the main mechanism of the removal. In addition to displacement of hexadecane droplets from subsurface porous matrixes, dispersion or emulsification of hexadecane into surfactant solution also played an important role in hexadecane removal. The performance of this anionic rhamnolipid surfactant is greatly affected by the addition of electrolytes and the change of pH. Addition of Na⁺ and Mg²⁺ can significantly increase the solubilization capacity of rhamnolipid and reduce the interfacial tension between hexadecane and surfactant solution, while addition of Ca²⁺ has a competing effects of enhanced solubilization and Ca²⁺ induced rhamnolipid precipitation. Control of ionic strength and pH can be used to optimize surfactant systems to enhance the NAPL removal depending on the nature of NAPL (LNAPL or DNAPL). Addition of rhamnolipid can also enhance the transport of three bacterial cells with varying hydrophobicity, P. aeruginosa ATCC 9027, 27853, and 15442, by decreasing cell adsorption. This is because the adsorption of surfactant to the porous medium surface increases the surface negative charge density, hence the adsorption of bacteria to the surface is reduced. No significant influence of rhamnolipid on the bacteria surface properties is observed. The measured bacteria breakthrough curves were simulated by an advection-dispersion transport model incorporating two domain reversible sorption (instantaneous and rate-limited) and with two first order sink terms for irreversible sorption. Model simulation suggests that rhamnolipid mainly affects the irreversible sorption of cells.
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Harding, S. G. "NMR studies of structure-transport relationships in porous media : liquid diffusion in polymers." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603691.
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The main motivation behind this work was to explore the potential of nuclear magnetic resonance (NMR) to study small molecule diffusion in porous materials and the relationship between structure and transport processes, with particular emphasis on liquid diffusion in polymers. The diffusion of small hydrocarbons into a range of semicrystalline polyethylene (PE) samples is studied. Under the penetration conditions employed the polymer crystallinity is retained, supporting the idea that the penetrant resides only in the amorphous region. Magnetic resonance imaging (MRI) is used to monitor the bulk transport of penetrating liquids into the polymers. Pulsed Gradient Spin Echo (PGSE) NMR is used to measure the self diffusivity of the penetrant. The transport diffusivity estimated from MRI shows good agreement with the self diffusivity when the degree of crystallinity is taken into account. The data presented show the importance of the phase and chain structure of the polymer on the diffusion and mobility of the penetrating species. Deuterium NMR relaxation time and line shape analysis is used to measure the correlation time of various motional process. By comparing the correlation time for translational motion with the PGSE self diffusivity it has been possible to estimate the penetrant jump distance to be in the order of a few nanometers. Molecular Dynamics (MD) simulations of hexane diffusion in amorphous PE are shown to give reasonable agreement with PGSE results. A mesoscopic lattice model is used to include the effect of the impenetrable crystallites on the diffusion process. Preliminary results using 31P NMR spectroscopy to study the mobility and molecular scale distribution of additives show that some additives intimately mixed with the polymer while some reside in a discrete domain of around 100 nm. Diffusion weighted imaging is used to study liquid diffusion into polyethylene oxide (PEO) hydrogel. Despite the diffusion kinetics showing Fickian behaviour the concentration dependence of the diffusivity calculated from the PGSE measurements and from the concentration profiles are significantly different, highlighting the importance of the polymer chains in controlling the diffusion process. Three dimensional imaging shows that structural heterogeneities in catalyst support pellets can be characterised by a fractal parameter. The importance of slice thickness in determining the distribution of T1 times from a 2D image is highlighted. NMR cryoporometry is used to measure the pore size distribution and the results compare well in nitrogen adsorption, and T1 measurements. NMR cryoporometry is combined with MRI and the spatial variations in the pore size distribution are shown to be similar to those previously observed through NMR spin density and relaxation imaging.
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Khodaverdian, Alfred. "An experimental study of added mass effects in two phase solid/liquid media." Thesis, University College London (University of London), 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285249.
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Pham, Quang Nhat. "Fabrication of Copper Inverse Opals for Microscale Liquid Transport in Polycrystalline Porous Media." Thesis, University of California, Irvine, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10828027.
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The continually increasing power density of high-performance electronics is bottlenecked by the challenges faced with thermal management requirements for reliable operation. While the traditional convective air-cooling approach is limited in its effectiveness at dissipating high heat fluxes, the use of latent heat in liquid-vapor phase change is an attractive strategy for managing the most aggressive thermal loading demands. Passive two-phase cooling operates by capillary pumping fluid through void spaces within porous metals to transport energy over long distances. The performance of such liquid delivery through porous structures is governed by the pore distribution, porosity, and morphology. Analogous to energy transport in polycrystalline solids, hydraulic transport in polycrystalline porous media is also limited by structural defects and grain boundaries. This work reports on the capillary performances of both single- and polycrystalline microporous copper with varying pore diameters from 300 to 1000 nm. The hydraulic transport through the arrays of interconnected spherical pores is modeled and quantified with experimental wicking measurements, and the influence of grain boundaries on the hydraulic transport in polycrystalline microporous media contributes to the hydraulic resistance presented by the structural defects. By combining multiple pore diameters and systematically layering them, this study creates heterogeneous porous media to emulate the transport within biological systems. The gradient layering of pores enhances the liquid delivery by circumventing grain boundary defects in three dimensions. The fundamental understanding of hydraulic transport physics through porous crystals and boundaries will pave the way for the spatial design of heterogeneous porous materials for future capillary-driven technologies.
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Yien, Linen Ling-Ying. "An investigation into the electro-convective motions of liquid hydrocarbons in porous media." Thesis, University of Bristol, 1992. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333873.
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Fang, Jia. "Study of Liquid Drop Migration on Fibers and Mats due to Liquid Flow in a Thin Slit Geometry." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1446730097.
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Wheeler, Christopher J. "Liquid cinema and the re-creation of thought: towards a philosophy of filmind." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/13023.
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Includes bibliographical references.This research is towards the advancement of filmosophy as a progressive new approach to how we think about, and through, film. This explorative research aims to introduce, contextualise, and expand upon the thoughts and writings of Daniel Frampton, as found in his 2006 manifesto: Filmosophy. In order to provide a suitable platform from which to introduce Frampton’s contemporary concepts (i.e. ‘filmind’ and ‘fluid film-thinking’), this paper first outlines and discusses the various ways in which philosophy and film are said to overlap, culminating in a critical discussion of ‘film-as-philosophy’ in terms of the implications it posits for providing innovative philosophical contributions through uniquely cinematic means (the ‘problem of paraphrase’). This literature review concludes by presenting and discussing filmosophy and its major tenets as both an appropriate extension of the current canon, and as a potentially productive new paradigm through which both film and philosophy can be critically considered and advanced.
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Noman, Rashed. "High velocity gas flow in porous media : effects of pore structure and liquid saturation." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47205.
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Koujout, Said. "The influence of liquid reaction media on acidities and activities of solid acid catalysts." Thesis, University of Huddersfield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288505.
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Novel H+ -sulfori"ated poly( styrene-co-divinylbenzene) ion-exchange resins have been prepared with· higher acid strength and higher thermal stabilities than conventionai ion-exchange resins. An objective of the study has been to increase the understanding of the relationships between resins structures, acidities and acid catalytic activities in aqueous and non-aqueous media. Some related materials, supported sulfonic acid catalysts, have been prepared using HMS (hexagonal mesoporous silicas) and SBA 15 as supports. These catalysts were characterised in terms of surface area and pore size distribution from nitrogen adsorption, powder X-ray diffraction, cation exchange capacity, thermogravimetric analysis and FT-Raman spectroscopy. These functionalised inorganic materials have been compared with their organic counterparts to improve the understanding of these systems. Both of these ranges of catalysts, with varying level of sulfonation, have been characterised by ammonia adsorption microcalorimetry in the absence of solvent. The resulting molar enthalpies of ammonia adsorption have been interpreted in terms of the relative strength of acid sites. The same catalysts have also been neutralised in a titration microcalorimeter (TITRYS) in which the materials have been held under a solvent (water, acetonitrile, cyclohexane) and a base probe compound titrated into the sample cell in the same solvent. Molar enthalpies of neutralisation measured for thes'e solid acid catalysts in this way have been compared with molar enthalpies of neutralisc:!ion for similar acid groups (sulfonic acids) in homogeneous solutions. The resulting molar enthalpies of neutralisation in non-aqueous solvents have been interpreted in terms of the relative strength of acid sites. In addition, FT-Raman spectroscopy has been used to study the sulfonic acid groups in the resin gels and comparison made with similar acid groups in homogeneous aqueous solutions. These in turn have been compared with catalytic data measured for the sulfonated catalysts in three liquid phase reactions. Variation in measured acidity (with and without) solvent, catalytic activities have been interpreted in terms of structural features of the catalysts and their interaction with solvents.
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Afonso, Josiana Prado. "Towards cryogenic liquid –vapor energy storage units for space applications." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10158.
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Dissertation to obtain the Doctoral degree
in Physics EngineeringWith the development of mechanical coolers and very sensitive cryogenic sensors, it could be interesting to use Energy Storage Units (ESU) and turn off the cryocooler to operate in a free micro vibration environment. An ESU would also avoid cryogenic systems oversized to attenuate temperature fluctuations due to thermal load variations which is useful particularly for space applications. In both cases, the temperature drift must remain limited to keep good detector performances. In this thesis, ESUs based on the high latent heat associated to liquid-vapor phase change to store energy have been studied. To limit temperature drifts while keeping small size cell at low temperature, a potential solution consists in splitting the ESU in two volumes: a low temperature cell coupled to a cryocooler cold finger through a thermal heat switch and an expansion volume at room temperature to reduce the temperature increase occurring during liquid evaporation. To obtain a vanishing temperature drift, a new improvement has been tested using two-phase nitrogen: a controlled valve was inserted between the two volumes in order to control the cold cell pressure. In addition, a porous material was used inside the cell to turn the ESU gravity independent and suitable for space applications. In this case, experiments reveal not fully understood results concerning both energy storage and liquid-wall temperature difference. To capture the thermal influence of the porous media, a dedicated cell with poorly conductive lateral wall was built and operated with two-phase helium. After its characterization outside the saturation conditions (conduction, convection), experiments were performed, with and without porous media, heating at the top or the bottom of the cell with various heat fluxes and for different saturation temperatures. In parallel, a model describing the thermal response for a cell containing liquid and vapor with a porous medium heated at the top (“against gravity”) was developed. The experimental data were then used as a benchmark for this model based on a balance of three forces: capillarity force, gravity force and pressure drop induced by the liquid flow.
Fundação da Ciência e da Tecnologia - PhD scholarship(SFRH/BD/60357/2009); project “Cryogenic Temperature Stabilizers” (PTDC/EME-MFE/101448/2008)
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Chawich, Juliana. "ZnO/GaAs-based acoustic waves microsensor for the detection of bacteria in complex liquid media." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD012/document.
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Cette thèse s’inscrit dans le cadre d’une cotutelle internationale entre l’Université de Bourgogne Franche-Comté en France et l’Université de Sherbrooke au Canada. Elle porte sur le développement d'un biocapteur miniature pour la détection et la quantification de bactéries dans des milieux liquides complexes. La bactérie visée est l’Escherichia coli (E. coli), régulièrement mise en cause dans des épidémies d'infections alimentaires, et parfois meurtrière.La géométrie du biocapteur consiste en une membrane en arséniure de gallium (GaAs) sur laquelle est déposé un film mince piézoélectrique d’oxyde de zinc (ZnO). L'apport du ZnO structuré en couche mince constitue un réel atout pour atteindre de meilleures performances du transducteur piézoélectrique et consécutivement une meilleure sensibilité de détection. Une paire d'électrodes déposée sur le film de ZnO permet de générer sous une tension sinusoïdale une onde acoustique se propageant dans le GaAs, à une fréquence donnée. La face arrière de la membrane, quant à elle, est fonctionnalisée avec une monocouche auto-assemblée (SAM) d'alkanethiols et des anticorps anti-E. coli, conférant la spécificité de la détection. Ainsi, le biocapteur bénéficie à la fois des technologies de microfabrication et de bio-fonctionnalisation du GaAs, déjà validées au sein de l’équipe de recherche, et des propriétés piézoélectriques prometteuses du ZnO, afin d’atteindre potentiellement une détection hautement sensible et spécifique de la bactérie d’intérêt. Le défi consiste à pouvoir détecter et quantifier cette bactérie à de très faibles concentrations dans un échantillon liquide et/ou biologique complexe.Les travaux de recherche ont en partie porté sur les dépôts et caractérisations de couches minces piézoélectriques de ZnO sur des substrats de GaAs. L’effet de l’orientation cristalline du GaAs ainsi que l’utilisation d’une couche intermédiaire de Platine entre le ZnO et le GaAs ont été étudiés par différentes techniques de caractérisation structurale (diffraction des rayons X, spectroscopie Raman, spectrométrie de masse à ionisation secondaire), topographique (microscopie à force atomique), optique (ellipsométrie) et électrique. Après la réalisation des contacts électriques, la membrane en GaAs a été usinée par gravure humide. Une fois fabriqué, le transducteur a été testé en air et en milieu liquide par des mesures électriques, afin de déterminer les fréquences de résonance pour les modes de cisaillement d’épaisseur. Un protocole de bio-fonctionnalisation de surface, validé au sein du laboratoire, a été appliqué à la face arrière du biocapteur pour l’ancrage des SAMs et des anticorps, tout en protégeant la face avant. De plus, les conditions de greffage d’anticorps en termes de concentration utilisée, pH et durée d’incubation, ont été étudiées, afin d’optimiser la capture de bactérie. Par ailleurs, l’impact du pH et de la conductivité de l’échantillon à tester sur la réponse du biocapteur a été déterminé. Les performances du biocapteur ont été évaluées par des tests de détection de la bactérie cible, E. coli, tout en corrélant les mesures électriques avec celles de fluorescence. Des tests de détection ont été réalisés en variant la concentration d’E. coli dans des milieux de complexité croissante. Différents types de contrôles ont été réalisés pour valider les critères de spécificité. En raison de sa petite taille, de son faible coût de fabrication et de sa réponse rapide, le biocapteur proposé pourrait être potentiellement utilisé dans les laboratoires de diagnostic clinique pour la détection d’E. coliThis thesis was conducted in the frame of an international collaboration between Université de Bourgogne Franche-Comté in France and Université de Sherbrooke in Canada. It addresses the development of a miniaturized biosensor for the detection and quantification of bacteria in complex liquid media. The targeted bacteria is Escherichia coli (E. coli), regularly implicated in outbreaks of foodborne infections, and sometimes fatal.The adopted geometry of the biosensor consists of a gallium arsenide (GaAs) membrane with a thin layer of piezoelectric zinc oxide (ZnO) on its front side. The contribution of ZnO structured in a thin film is a real asset to achieve better performances of the piezoelectric transducer and consecutively a better sensitivity of detection. A pair of electrodes deposited on the ZnO film allows the generation of an acoustic wave propagating in GaAs under a sinusoidal voltage, at a given frequency. The backside of the membrane is functionalized with a self-assembled monolayer (SAM) of alkanethiols and antibodies anti-E. coli, providing the specificity of detection. Thus, the biosensor benefits from the microfabrication and bio-functionalization technologies of GaAs, validated within the research team, and the promising piezoelectric properties of ZnO, to potentially achieve a highly sensitive and specific detection of the bacteria of interest. The challenge is to be able to detect and quantify these bacteria at very low concentrations in a complex liquid and/or biological sample.The research work partly focused on the deposition and characterization of piezoelectric ZnO thin films on GaAs substrates. The effect of the crystalline orientation of GaAs and the use of a titanium / platinum buffer layer between ZnO and GaAs were studied using different structural (X-ray diffraction, Raman spectroscopy, secondary ionization mass spectrometry), topographic (atomic force microscopy), optical (ellipsometry) and electrical characterizations. After the realization of the electrical contacts on top of the ZnO film, the GaAs membrane was micromachined using chemical wet etching. Once fabricated, the transducer was tested in air and liquid medium by electrical measurements, in order to determine the resonance frequencies for thickness shear mode. A protocol for surface bio-functionalization, validated in the laboratory, was applied to the back of the biosensor for anchoring SAMs and antibodies, while protecting the top side. Furthermore, different conditions of antibody grafting such as the concentration, pH and incubation time, were tested to optimize the immunocapture of bacteria. In addition, the impact of the pH and the conductivity of the solution to be tested on the response of the biosensor has been determined. The performances of the biosensor were evaluated by detection tests of the targeted bacteria, E. coli, while correlating electrical measurements with fluorescence microscopy. Detection tests were completed by varying the concentration of E. coli in environments of increasing complexity. Various types of controls were performed to validate the specificity criteria. Thanks to its small size, low cost of fabrication and rapid response, the proposed biosensor has the potential of being applied in clinical diagnostic laboratories for the detection of E. coli