Dissertations / Theses: 'Suspensions, chemistry'

1

Amarasinghe, B. M. W. P. K. "Sedimentation behaviour of complex polydisperse suspensions." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293935.

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Qi, Yabing. "Field-induced phenomena in colloidal suspensions /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202002%20QI.

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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.
Includes bibliographical references (leaves 57-60). Also available in electronic version. Access restricted to campus users.

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Green, Matthew Daryl. "Characterisation of suspensions in settling and compression /." Connect to thesis, 1997. http://eprints.unimelb.edu.au/00000987.

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Dong, Xue Min. "Chiral nematic ordered suspensions of cellulose microcrystallites." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=42018.

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Suspensions of rod-like cellulose microcrystallites, 50-250 nm in length and $ sim$7 nm in width, and with negatively charged sulfate groups on the surface have been prepared. When the concentration of cellulose microcrystallites exceeds a critical value, the suspension separates into two phases, forming an upper isotropic phase and a lower chiral nematic anisotropic phase. The critical concentration for phase separation is very sensitive to the ionic strength, particle size, polydispersity of particles, counterion species, and preparation conditions. When the suspension is in pure water and in the biphasic region, the coexisting concentrations in both phases increase with the increase of total cellulose concentration. Suspensions with different counterions have different critical concentrations for phase separation. The critical concentration increases in the order $ rm H sb3{O sp+} < {Na sp+} < {K sp+} < Cs sp+$ for inorganic counterions, and generally increases with increasing counterion size for some organic counterions. The salt-form suspensions demonstrate a good stability with temperature, but the acid-form suspension is unstable at temperatures higher than $50 sp circ$C. The suspensions show induced circular dichroism in the presence of dye, such as Congo red. The anisotropic phase has a very strong negative ICD peak when viewed along the chiral nematic axis, and the peak is much weaker when viewed at right angles to the axis. The isotropic suspension shows a small positive ICD peak. The behavior of the phase separation was compared with the theoretical predictions of Stroobants et al., and a relatively good agreement was obtained between theory and experimental data for suspensions in pure water.

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Edgar, Catherine D. "Characterization of suspensions and films of cellulose nanocrystals." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37663.

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Suspensions of cellulose nanocrystals may be prepared by hydrolysing wood pulp or cotton filter paper with sulfuric acid. Due to the rod-like shape of the nanocrystals, these aqueous suspensions display liquid crystalline behaviour. This thesis examines these unique suspensions at three different concentration ranges. At low cellulose concentrations the suspensions are disordered, becoming ordered upon reaching a critical concentration, which depends on the aspect ratio of the rods. AFM and TEM were used to characterize particle size and polydispersity. Just beyond the critical concentration for anisotropic phase formation is an intermediate concentration range in which the isotropic and anisotropic phases co-exist. This biphasic region was examined for its potential to partition dextran molecules. At extremely high cellulose concentrations, solid cellulose films that maintain some chiral nematic order may be obtained. The degree of order in the films has been measured using induced circular dichroism and optimized by magnetic alignment. These suspensions can also be used to create model surfaces of cellulose I. The smooth cellulose surfaces have been characterized by XPS, X-ray diffraction, and AFM.

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Johnson, Timothy Jay. "Electrokinetic clarification of concentrated colloidal suspensions /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9905.

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Jardali, Fadi Samir. "Investigations into thermodynamic properties of colloidal-sphere suspensions." Thesis, University of Bradford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292717.

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8

Knott, Michael. "Phases and phase transitions in charged colloidal suspensions." Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270941.

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Lukner, Ralf Bernhard. "Piston-driven flow of highly concentrated suspensions /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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10

Aguilar, Martha. "Photocatalytic decomposition of organophosphonates fluorophenols in irradiated titanium dioxide suspensions." FIU Digital Commons, 1997. http://digitalcommons.fiu.edu/etd/1161.

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Dimethyl methyl phosphonate (DMMP), diethyl methyl phosphonate (DEMP), and fluorophenols undergo rapid decomposition upon TiO2 catalyzed photooxidation in air saturated aqueous solution. The degradation rates of DMMP were determined over a range of temperatures, under solar and artificial irradiation with and without simultaneous sonication. Solar illumination is effective for the degradation and the use of low energy of sonication increases the rate of mineralization. The surface area and the type of TiO2 dramatically affect the photoactivity of the catalyst. A number of intermediate products are formed and ultimately oxidized to phosphate and carbon dioxide. Possible reaction mechanisms and pathways for DMMP and DEMP are proposed. The Langmuir- Hinshelwood kinetic parameters for the photocatalysis of fluorophenols suggest modestly different reactivity for each isomer. The adsorption constant is largest for the ortho isomer consistent with the adsorption onto TiO2 through both hydroxyl and fluoride groups to form a chelated type structure.

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Abanzukwe, T. C. "Interactions of β-blockers with cell suspensions." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/33121.

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Joung, Clint G. "Direct simulation studies of suspended particles and fibre-filled suspensions." Connect to full text, 2003. http://hdl.handle.net/2123/554.

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Thesis (Ph. D.)--University of Sydney, 2004.
Title from title screen (viewed 16 April 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Aerospace, Mechanical and Mechatronic Engineering. Degree awarded 2004; thesis submitted 2003. Contains published article co-authored by Joung. Includes bibliographical references. Also available in print form.

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Furbank, Roy Jeffrey. "Drop formation from particulate suspensions." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-05172004-100527/unrestricted/furbank%5Froy%5Fj%5F200407%5Fphd.pdf.

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Thesis (Ph. D.)--School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2005. Directed by F. Joseph Schork.
Schork, F. Joseph, Committee Chair ; Morris, Jeffrey F., Committee Co-Chair ; Forney, Larry J., Committee Member ; Breedveld, Victor, Committee Member ; Mucha, Peter J., Committee Member ; Smith, Marc K., Committee Member. Includes bibliographical references.

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Usher, Shane Patrick. "Suspension dewatering : characterisation and optimisation /." Connect to thesis, 2002. http://eprints.unimelb.edu.au/archive/00000972.

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Vasheghani-Farahani, Ebrahim. "Filtration of fine suspensions in an electrofluidized bed." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66042.

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Katyal, Bhavana. "Microstructural features in sheared suspensions : probability wake an triplet correlation." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/11259.

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17

Reinhart, Chase Collier. "Formulation of Colloidal Suspensions of 3-mercaptopropionic acid capped PbS Quantum Dots as Solution Processable QD "Inks" for Optoelectronic Applications." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3289.

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The use of colloidal quantum dots (QDs) for photovoltaic energy conversion is a nascent field that has been dominated for well over a decade by the use of 3-mercaptopropionic acid (3-MPA) capped PbS QDs. These QDs are routinely deposited via an in situ solid state ligand exchange process that displaces the native oleate ligand on the PbS QD surface. This ligand exchange procedure is wasteful of material and has been demonstrated to leave numerous impurities that limit electronic performance of the as-deposited QD devices. Until the last few years there was very little understanding in chemical literature as to many important aspects of QD chemistry for this material pairing outside the framework of a QD solid. In this work, a colloidal suspension of 3-MPA capped PbS QDs in DMSO was formulated and investigated to probe ligand dynamics and optical properties of the suspended colloid. QD bound 3-MPA was found to be in dynamic exchange with "free" ligand in solution by 1H-NMR spectroscopy. Optical properties and colloidal stability were found to be heavily dependent on the presence of a significant excess of free ligand. PbS QDs were also found to be highly photo-catalytic towards oxidative dimerization of 3-MPA to its dimer, dithiodipropionic acid (dTdPA). After an initial colloidal suspension was achieved, attempts were made to directly deposit the colloid as a QD "ink" to form optoelectronic devices. While photo-switchable devices were obtained, ultimately it was determined that DMSO was a largely incompatible solvent choice for solution processing methodologies. Subsequently, 3-MPA capped PbS QD colloids were obtained in volatile organic solvents amenable to solution processing by the addition of a stabilizing ammonium salt. These QD colloids maintained excellently resolved optical properties and were able to form conformal coatings from simple evaporative deposition. The ligand chemistry of this colloid was extensively investigated via NMR and optical spectroscopy. These QDs were also found to be highly photo-catalytic towards conversion of monomer 3-MPA to dTdPA.

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Bell, Martin Derek. "Ordering of particulate suspensions in Couette flow at moderate Reynolds numbers." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28901.

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A remarkable ordering phenomenon has been seen to occur when a suspension of particles undergoes shear at particle Reynolds numbers of the order of or greater than one in the annular gap of a Couette type shearing device. This particulate ordering was observed and studied with both suspensions of rigid spheres and suspensions of polystyrene latex aggregates formed in the presence of shear within the gap. Each of these systems was studied under a variety of initial conditions in order to define the particular flow conditions required for particle alignment to occur. It was found that particulate ordering occurred under similar conditions to those used by Segré and Silberberg (35) to observe the "necklace formations" that formed within particulate suspensions flowing inside tubes. The separations between aligned particles was found to be strongly dependent on the particle Reynolds number and the ratio between the particle diameter and the width of the annular gap. An insight into the hydrodynamic interactions occurring was provided by the comparisons made between the ordered aggregates and the ordered rigid spheres under similar flow conditions.
Science, Faculty of
Chemistry, Department of
Graduate

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Luu, Wing T. "Effect of Aluminum Sulfate and Sodium Alumniate on the Drainage and Retention Properties of Fibrous Suspensions." Fogler Library, University of Maine, 2005. http://www.library.umaine.edu/theses/pdf/LuuWT2005.pdf.

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20

Brickman, Larry A. "Numerical evaluation of the pair-distribution function of dilute suspensions at high Péclet number." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/11305.

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21

Dobson, Regina Louise. "Electrocoagulation concept for the separation of ultrafines." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/11855.

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22

Moragudivenkata, Madana M. "Consumer and descriptive analysis of flavored omeprazole oral suspensions." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/5879.

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Thesis (M.S.)--University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Aug. 29, 2007). Includes bibliographical references.

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23

Duan, Jinming. "Influence of dissolved silica on flocculation clay suspensions with hydrolysing metal salts." Thesis, University College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264932.

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24

Ducay, Rey Nann Mark Abaque. "Direct Detection of Aggregates in Turbid Colloidal Suspensions." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1439434385.

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25

Mao, Wenbin. "Modeling particle suspensions using lattice Boltzmann method." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50349.

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Particle suspensions are common both in nature and in various technological applications. The complex nature of hydrodynamic interactions between particles and the solvent makes such analysis difficult that often requires numerical modeling to understand the behavior of particle suspensions. In this dissertation, we employ a hybrid computational model that integrates a lattice spring model for solid mechanics and a lattice Boltzmann model for fluid dynamics. We use this model to study several practical problems in which the dynamics of spherical and spheroidal particles and deformable capsules in dilute suspensions plays an important role. The results of our studies yield new information regarding the dynamics of solid particle in pressure-driven channel flows and disclose the nonlinear effects associated with fluid inertia leading to particle cross-stream migration. This information not only give us a fundamental insight into the dynamics of dilute suspensions, but also yield engineering guidelines for designing high throughput microfluidic devices for sorting and separation of synthetic particles and biological cells. We first demonstrate that spherical particles can be size-separated in ridged microchannels. Specifically, particles with different sizes follow distinct trajectories as a result of the nonlinear inertial effects and secondary flows created by diagonal ridges in the channel. Then, separation of biological cells by their differential stiffness is studied and compared with experimental results. Cells with different stiffness squeeze through narrow gaps between solid diagonal ridges and channel wall, and migrate across the microchannel with different rates depending on their stiffness. This deformability-based microfluidic platform may be valuable for separating diseased cells from healthy cells, as a variety of cell pathologies manifest through the change in mechanical cell stiffness. Finally, the dynamics of spheroid particles in simple shear and Poiseuille flows are studied. Stable rotational motion, cross-stream migration, and equilibrium trajectories of non-spherical particles in flow are investigated. Effects of particle and fluid inertia on dynamics of particles are disclosed. The dependence of equilibrium trajectory on particle shape reveals a potential application for shape based particle separation.

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Wang, Gonghou. "Ionic stability of oxide particles in polar organic media /." *McMaster only, 1998.

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Hikkaduwa, Koralege Rangika S. "Oxidative behavior and thermal stability of C60 colloidal suspensions in water and C60/gamma-cyclodextrin polymer networks." Thesis, Oklahoma State University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3728840.

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Since its discovery in 1985, buckminsterfullerene (C₆₀) has been extensively studied due to its unique properties and it's now being produced in multi-ton quantities. The ability to form stable aqueous C₆₀ colloids (known as nano-C₆₀ or nC₆₀) and the availability of these in natural systems at environmentally-relevant concentrations led to significant interest concerning the environmental health and safety of these colloidal aggregates. Addressing two issues with regard to this material's environmental health and safety concerns we have looked at the oxidative mechanism of these nC₆₀ colloidal aggregates and their thermal stability. For making accurate kinetics and measurements on oxidation caused by aqueous-nC₆₀ colloidal dispersions, we have developed experimental methods utilizing dihydrorhodamine 123 (DHR123) as a sacrificial probe molecule to monitor oxidation by fluorescence spectroscopy and kinetic models to explain observed oxidation. Evaluation of the oxidative behavior of fullerene colloids has been determined using the oxidation rate as a function of nC₆₀ concentration, nC₆₀ surface area, number of colloidal particles and C₆₀O content, operating where necessary under inert atmosphere and oxygen rich conditions. The effect of temperature on these colloids plays a significant role in both their synthesis and reactivity. Given that the colloids are mainly composed of C₆₀ and C₆₀O, C₆₀O might play a significant role in stabilizing the colloid, hence increasing the temperature might cause thermally-activated reactions with C₆₀O. Thermal stability of these colloids prepared by all four primary nC₆₀ synthesis methods has been investigated. Incorporation of C₆₀ into polymers is of potential interest for applications, for sequestration to address potential environmental health and safety issues, and as a component in novel architectures. A new composite material was developed by encapsulating C₆₀ into cross-linked polymer network formed by γ-cyclodextrin. A simple synthesis route to achieve composite membranes of intercalated C₆₀ in the polymer network is presented.

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Cerbelaud, M. "Hétéroagglomération de suspensions céramiques : une étude numérique." Phd thesis, Université de Limoges, 2008. http://tel.archives-ouvertes.fr/tel-00344058.

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L'hétéroagglomération a été étudiée dans des suspensions céramiques mixtes aluminesilice diluées, par deux types de simulations numériques : dynamique Brownienne et minimisation globale. Les simulations ont été appliquées à un premier système, où les particules d'alumine et de silice sont de tailles peu différentes. Elles ont permis d'analyser la composition et la structure des agglomérats obtenus. Elles ont ensuite été adaptées à un deuxième système, où les particules de silice sont seize fois plus petites que celles d'alumine. Dans ce cas, elles ont montré que les particules de silice s'adsorbent sur l'alumine et que l'agglomération des particules d'alumine, fortement chargées, est possible, par l'intermédiaire de la silice qui se place entre elles. Les agglomérats obtenus sont très allongés bien que les formes d'équilibre soient plus compactes. Les observations expérimentales effectuées sur les deux systèmes sont en accord avec les résultats de ces simulations.

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Kotze, Reinhardt. "Rheological characterisation of highly concentrated mineral suspensions using an ultrasonic velocity profiler." Thesis, Cape Peninsula University of Technology, 2007. http://hdl.handle.net/20.500.11838/1150.

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Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2007
The rheological behaviour of non-Newtonian, highly concentrated and non-transparent fluids used in industry have so far been analysed using commercially available instruments, such as conventional rotational rheometers and tube viscometers. When dealing with the prediction of non-Newtonian flows in pipes, pipe fittings and open channels, most of the models used are empirical in nature. The fact that the fluids or slurries that are used normally are opaque, effectively narrows down the variety of applicable in-line rheometers even further, as these instruments are normally based on laser or visible light techniques, such as Laser Doppler Anemometry. Electrical Resistance Tomography is a non-invasive method used to look into opaque suspensions during pipe flow, but cannot be used to measure in-line rheometry. In this research, an Ultrasound Pulsed Echo Doppler Velocity Profile technique (UVP), in combination with a pressure difference (PD) was tested to provide in-line measurement of rheological parameters. The main objective ofthis research was to evaluate the capabilities of the UVP-PD technique for rheological characterisation of different concentrations of non-transparent non-Newtonian slurries. A unique pipe viscometer was designed and constructed. It consisted of four pipes, one of stainless steel and three of PVC, linked to an in-line mass-flow meter and equipped with two different ranges of pressure transducers on each pipe. The stainless steel pipe, with an inner diameter of 16 mm, was equipped with a specially designed flow adapter for in-line rheological characterisation using the UVP-PD method. The three PVC pipes with different diameters of 9 mm, 13 mm and 16 mm served as a tube viscometer for in-line rheological characterisation of mineral suspensions.

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Beck, Stephanie Christine. "Phase separation phenomena in cellulose nanocrystal suspensions containing dextran-dye derivatives." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102956.

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Sulfuric acid hydrolysis of native cellulose fibers produces stable suspensions of cellulose nanocrystals. Within a specific concentration range, the suspensions spontaneously form an anisotropic chiral nematic liquid crystal phase. This thesis examines the phase separation behaviour of these suspensions, alone and in the presence of added macromolecules. Initially, the effect of hydrolysis conditions on the nanocrystal and phase separation properties for hydrolyzed softwood pulp were investigated and compared to suspensions prepared from hardwood pulp. The macromolecules studied, blue dextrans of varying molecular weights and dye ligand densities, were synthesized and characterized with a number of techniques. The polyelectrolytic nature of these macromolecules was found to strongly influence their physico-chemical properties. Added blue dextran causes separation of an isotropic phase from highly concentrated, completely anisotropic suspensions. The observed phase separation was found to be associated with the charged dye molecules attached to the dextran. The partitioning behaviour of blue dextrans in biphasic aqueous suspensions of native cellulose nanocrystals was also studied with regard to the effect of total concentration of blue dextran, degree of dye substitution and dextran molecular weight on the blue dextran partition coefficient. Electrostatic and entropic contributions to the partition coefficient of blue dextran were discussed. Triphase isotropic-isotropic-nematic (I1--I 2--N) equilibria are observed in suspensions containing both neutral dextrans and polyelectrolytic blue dextrans of varying molecular weight. Based on these results, phase diagrams for cellulose nanocrystal suspensions with different combinations of dextran and blue dextran are presented.

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Alarcón, Oseguera Francisco. "Computational study of the emergent behavior of micro-swimmer suspensions." Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/394065.

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It is known that active particles induce emerging patterns as a result of their dynamic interactions, giving rise to amazing collective motions, such as swarming or clustering. Here we present a systematic numerical study of self-propelling particles; our main goal is to characterize the collective behavior of suspensions of active particles as a result of the competition among their propulsion activity and the intensity of an attractive pair potential. Active particles are modeled using the squirmer model. Due to its hydrodynamic nature, we are able to classify the squirmer swimmer activity in terms of the stress it generates (referred to as pullers or pushers). We show that these active stresses play a central role in the emergence of collective motion. We have found that hydrodynamics drive the coherent swimming between swimmers while the swimmer direct interactions, modeled by a Lennard-Jones potential, contributes to the swimmers' cohesion. This competition gives rise to two different regimes where giant density fluctuations (GDF) emerge. These two regimes are differentiated by the suspension alignment; one regime has GDF in aligned suspensions whereas the other regime has GDF of suspensions with an isotropic orientated state. All the simulated squirmer suspensions shown in this study were characterized by a thorough analysis of global properties of the squirmer suspensions as well as a complementary cluster analysis. Active matter refers generically to systems composed of self-driven units, active particles, each capable of converting stored or ambient free energy into systematic movement. Examples of active systems are found at all length scales and could be classified in living and nonliving systems such as microorganisms, tissues and organisms, animal groups, self- propelled colloids and artificial nanoswimmers. Specifically, at the micro and nano scale we find an enormous range of interesting systems both biological and artificial; e.g. spermatozoa that fuse with the ovum during fertilization, the bacteria that inhabit our guts, the protozoa in our ponds, the algae in the ocean; these are but a few examples of a wide biological spectrum. In the artificial world we have self- healing colloidal crystals and membranes as well as self- assembled microswimmers and robots. Experiments in this field are now developing at a very rapid pace and new theoretical ideas are needed to bring unity to the field and identify "universal" behavior in these internally driven systems. One important feature of active matter is that their elements can develop emergent, coordinated behavior; collective motion constitutes one of the most common and spectacular example. Collective motion is ubiquitous and at every scale, from herds of large mammals to amoeba and bacteria colonies, down to the cooperative behavior of molecular motors in the cell. The behavior of large fish schools and the dance of starling flocks at dusk are among the most spectacular examples. From a physical perspective collective motion emerges from a spontaneous symmetry breaking that allows for long-range orientational orden The different mechanisms responsible for such symmetry breaking are still not completely understood. We have performed a systematic numerical study of interactive micro-swimmer suspensions building on the squirmer model, introduced by Lighthill. Since the squirmer identifies systematically the hydrodynamic origin of self-propulsion and stress generation it provides a natural scheme to scrutinize the impact that the different features associated to self-propulsion in a liquid medium have in the collective dynamics of squirmer suspensions. In this abstract we describe the simulation scheme and how squirmers are modeled, then some of the main results are discussed and finally we conclude emphasizing the main implications of the results obtained.
Los sistemas activos se definen como materiales fuera del equilibrio termodinámico compuestos por muchas unidades interactuantes que individualmente consumen energía y colectivamente generan movimiento o estreses mecánicos. Ejemplos se pueden encontrar en un enorme rango de escalas de longitud, desde el mundo biológico hasta artificial, incluyendo organismos unicelulares, tejidos y organismos pluricelulares, grupos de animales, coloides auto-propulsados y nano-nadadores artificiales. Actualmente se están desarrollando experimentos en este campo a un ritmo muy veloz, en consecuencia son necesarias nuevas ideas teóricas para traer unidad al campo de estudio e identificar comportamientos “universales” en estos sistemas propulsados internamente. El objetivo de esta tesis es el estudiar mediante simulaciones numéricas, el comportamiento colectivo de un modelo de micro-nadadores. En particular, el modelo de squirmers, donde el movimiento del fluido es axi-simétrico. Existen estructuras coherentes que emergen de estos sistemas así que, el entender si las estructuras coherentes son generadas por la firma hidrodinámica intrínseca de los squirmers individuales o por un efecto de tamaño finito se vuelve algo de primordial importancia. Nosotros también estudiamos la influencia que tiene la geometría en la aparición de estructuras coherentes, la interacción directa entre las partículas, la concentración, etc.

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Normandin, Mélanie. "Étude sur la clarification d'une suspension de boue rouge et de liqueur Bayer par floculation /." Thèse, Chicoutimi : Université du Québec à Chicoutimi, 2005. http://theses.uqac.ca.

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Thèse (M.Eng.) -- Université du Québec à Chicoutimi, 2005.
La p. de t. porte en outre: Mémoire présenté à l'Université du Québec à Chicoutimi comme exigence partielle de la maîtrise en ingénierie. CaQQUQ Bibliogr.: f. 128-131. Document électronique également accessible en format PDF. CaQQUQ

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33

Ahmed, Syed Farid. "Kinetic modeling of dispersion polymerization in organic media." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/11800.

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34

Anderson, Sandie Lanclyn. "Flocculation of clay suspensions using synthetic polymers." Ohio : Ohio University, 1986. http://www.ohiolink.edu/etd/view.cgi?ohiou1183126556.

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35

Yearsley, Kathryn Margaret. "The effect of flow on carbon black and carbon nanotube suspensions." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610205.

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36

Judd, Simon. "The influence of an electric field on the filtration of aqueous suspensions through fibrous media." Thesis, Cranfield University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352931.

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Jarlbring, Mathias. "Characterisation and surface reactions of iron oxides and fluorapatite in aqueous suspensions." Licentiate thesis, Luleå, 2004. http://epubl.luth.se/1402-1757/2004/02.

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38

Kotzé, Reinhardt. "Rheological characterisation of highly concentrated mineral suspensions using an ultrasonic velocity profiler /." [S.l. : s.n.], 2007. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1037&context=td_cput.

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39

Tian, Fang, and n/a. "Towards a deeper understanding of the polymorphic conversion of carbamazepine in aqueous suspension." University of Otago. School of Pharmacy, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070601.135438.

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Polymorphism can influence every aspect of the properties of a solid including the shelf life, dissolution rate, solubility, formulation properties and processing properties of a solid drug. A deeper understanding of polymorphism and related solid state properties would ensure an improved quality of the materials used throughout drug preparation, dosage form formulation and clinical trials. Therefore, determination of the existence of polymorphs and pseudopolymorphs, characterization of different solid state forms and their respective properties, and controlling the existing form in the resulting formulation all form part of a rapidly growing field within pharmaceutical research and industry. Carbamazepine (CBZ) was the model drug used in this study. FT-Raman spectroscopy was chosen as a main investigative technique in this study to evaluate its potential in monitoring (pseudo)polymorphic conversions in aqueous suspensions in the absence or presence of various pharmaceutical excipients. Partial least squares analysis (PLS) was used for quantitative analysis of the spectral data. Earlier it has been found that CBZ converts rapidly to the dihydrate (DH) when exposed to humidity or water, and this has been reported to be the main reason for the sometimes observed greatly decreased bioavailability of marketed CBZ tablets. In this study, the conversion kinetics of CBZ (forms I, II and III) to DH in aqueous suspension were found to be first order kinetics with an unconverted portion (R� [greater than or equal to] 0.95), where the crystal morphology appeared to play a more important role in its conversion kinetics than the polymorphic form. The influence of pharmaceutical excipients on the conversion of CBZ in aqueous suspension was also explored. For excipients such as methylcellulose (MC), hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) which have both a low solubility parameter (< 27.0 MPa[1/2]) and strong hydrogen bonding groups, complete inhibition of the conversion of CBZ was possible even at a very low concentration (0.1 % w/v). Raman spectroscopy showed its high applicability in investigating CBZ conversion kinetics and screening of excipient effects in aqueous environment. It was demonstrated that Raman has a robust nature in quantitative analysis since problems such as different particle size, morphology, and spatial distribution of the two solid state forms of the drug seemed not to have significant influence on Raman scattering. This study has also clarified the relative importance of many contributing factors (type of crystalline form (CBZ or DH), crystal morphology, surface area, and excipient interactions with drug particles) influencing the in vitro dissolution of CBZ. The solid state characterization approach taken in this study will provide a deeper insight into the dissolution performance of drugs and should thus lead to a better understanding of in vitro/in vivo behavior of drugs.

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40

Han, Long. "Study of the rheological properties of Nomex fibrids." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2205.

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Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains ix, 110 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 54-59).

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41

Haji, Aghaee Khiabani Reza. "Heat transfer in nano/micro multi-component and complex fluids with applications to heat transfer enhancement." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/41154.

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Thermal properties of complex suspension flows are investigated using numerical computations. The objective is to develop an efficient and accurate computational method to investigate heat transport in suspension flows. The method presented here is based on solving the lattice Boltzmann equation for the fluid phase, as it is coupled to the Newtonian dynamics equations to model the movement of particles and the energy equation to find the thermal properties. This is a direct numerical simulation that models the free movement of the solid particles suspended in the flow and its effect on the temperature distribution. Parallel implementations are done using MPI (message passing interface) method. Convective heat transfer in internal suspension flow (low solid volume fraction, φ<10%), heat transfer in hot pressing of fiber suspensions and thermal performance of particle filled thermal interface materials (high solid volume fraction, φ>40%) are investigated. The effects of flow disturbance due to movement of suspended particles, thermo-physical properties of suspensions and the particle micro structures are discussed.

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42

Badaire, S. "Étude de suspensions et de fibres de nanotubes de carbone." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2005. http://tel.archives-ouvertes.fr/tel-00584150.

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Ce travail de thèse concerne l'étude de dispersions et de fibres de nanotubes de carbone. Nous nous sommes intéressés à l'influence de la structure des nanotubes et de la nature des dispersants sur la topologie des diagrammes de phases des suspensions. Nous montrons par ailleurs que les dimensions des nanotubes peuvent être caractérisées en suspension par diffusion dynamique dépolarisée de la lumière. Le deuxième aspect de ce travail concerne l'étude et l'optimisation des propriétés mécaniques, électriques et électromécaniques de fibres de nanotubes de carbone formulées grâce aux acquis de la partie précédente. Nous montrons que les fibres de nanotubes sont des systèmes prometteurs pour la réalisation de matériaux haute ténacité, de capteurs ou encore d'actionneurs électromécaniques.

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43

Bradbury, Andrew James. "A study of the effect of particle size polydispersity on the properties of concentrated aqueous colloidal silica suspensions." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240548.

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44

Salahuddin, Asif. "Orientation and rotational diffusion of fibers in semidilute suspension." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41163.

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The dynamics of fiber orientation is of great interest for efforts to predict the microstructure and material properties of a suspension flow system. In this research a fiber-level, hybrid simulation method, LBM‒EBF (coupled lattice‒Boltzmann method with the external boundary force method) is undertaken to advance the current understanding of the hydrodynamic interaction induced rotational diffusion mechanism for rigid fibers in semidilute suspension of low Reynolds number flow. The LBM‒EBF simulations correctly predict the orbit constant distribution of fibers in a sheared semidilute suspension flow. It is demonstrated that an anisotropic, weak rotary diffusion model can fit the orbit constant distribution very well, but it can not describe the asymmetry in Stokes flow observed in semidilute suspension. The rotational diffusion process is then characterized with a three dimensional spatial tensor representation of the rotational diffusivity. A scalar measure of the rotational diffusion‒'scalar Folgar‒Tucker constant', C[subscript I], is extracted from this tensor. The study provides substantial numerical evidence that the range of C[subscript I] (0.0038 to 0.0165) obtained by Folgar&Tucker (J. reinf. plast. and comp, v.3, 1984) in a semidilute regime is overly diffusive, and that the correct magnitude is of O(10⁻⁴). The study reveals that the interactions among fibers become more frequent with either the decrease of fiber aspect-ratio, r[subscript p] (keeping nL³ constant, where n is the fiber number density, and L is the fiber length) or with the increase of nL³ (keeping r[subscript p] constant) in the semidilute regime, which in consequence causes an increase in C[subscript I]. The rheological properties of sheared semidilute suspension are also computed with direct LBM‒EBF simulations. The LBM‒EBF investigation is extended to characterize the fiber orientation in a linearly contracting channel similar to a paper machine 'headbox'. It is found that the rotational diffusion is the predominant term over the strain rate in the semidilute regime for a low Reynolds number flow, and it results in a decreasing trend of rotational Peclet number, Pe, along the contraction centerline. Lastly, in order to improve the numerical consistency of the existing LBM‒EBF approach, a modification to the body force term in the LB equation is suggested, which can recover the exact macroscopic hydrodynamics from the mesoscale.

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45

Gonzalez-Ibarra, Alvaro. "The effects of polymeric binders on the processability and properties of composites made by suspension prepregging." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09192009-040513/.

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46

Zhou, Fangbin. "Inertial effects upon suspension shear flows : instability issue." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/10056.

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47

Lim, Amanda Seet Hwa. "Implementing the split Hopkinson pressure bar technique for complex fluid evaluation." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 252 p, 2010. http://proquest.umi.com/pqdweb?did=1992504671&sid=8&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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48

Clausen, Jonathan Ryan. "The effect of particle deformation on the rheology and microstructure of noncolloidal suspensions." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34680.

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In order to study suspensions of deformable particles, a hybrid numerical technique was developed that combined a lattice-Boltzmann (LB) fluid solver with a finite element (FE) solid-phase solver. The LB method accurately recovered Navier-Stokes hydrodynamics, while the linear FE method accurately modeled deformation of fluid-filled elastic capsules for moderate levels of deformation. The LB/FE technique was extended using the Message Passing Interface (MPI) to allow scalable simulations on leading-class distributed memory supercomputers. An extensive series of validations were conducted using model problems, and the LB/FE method was found to accurately capture proper capsule dynamics and fluid hydrodynamics. The dilute-limit rheology was studied, and the individual normal stresses were accurately measured. An extension to the analytical theory for viscoelastic spheres [R. Roscoe. J. Fluid Mech., 28(02):273-93, 1967] was proposed that included the isotropic pressure disturbance. Single-body deformation was found to have a small negative (tensile) effect on the particle pressure. Next, the rheology and microstructure of dense suspensions of elastic capsules were probed in detail. As elastic deformation was introduced to the capsules, the rheology exhibited rapid changes. Moderate amounts of shear thinning were observed, and the first normal stress difference showed a rapid increase from a negative value for the rigid case, to a positive value for moderate levels of deformation. The particle pressure also demonstrated a decrease in compressive stresses as deformation increased. The corresponding changes in microstructure were quantified. Changes in particle self-diffusivity were also noted.

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Little, Sylvia Bandy. "Multiphase flow through porous media." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/11779.

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Wu, Jingshu. "Direct simulation of flexible particle suspensions using lattice-boltzmann equation with external boundary force." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33858.

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Determination of the relation between the bulk or rheological properties of a particle suspension and its microscopic structure is an old and important problem in physical science. In general, the rheology of particle suspension is quite complex, and the problem becomes even more complicated if the suspending particle is deformable. Despite these difficulties, a large number of theoretical and experimental investigations have been devoted to the analysis and prediction of the rheological behavior of particle suspensions. However, among these studies there are very few investigations that focus on the role of particle deformability. A novel method for full coupling of the fluid-solid phases with sub-grid accuracy for the solid phase is developed. In this method, the flow is computed on a fixed regular 'lattice' using the lattice Boltzmann method (LBM), where each solid particle, or fiber, is mapped onto a Lagrangian frame moving continuously through the domain. The motion and orientation of the particle are obtained from Newtonian dynamics equations. The deformable particle is modeled by the lattice-spring model (LSM).The fiber deformation is calculated by an efficient flexible fiber model. The no-slip boundary condition at the fluid-solid interface is based on the external boundary force (EBF) method. This method is validated by comparing with known experimental and theoretical results. The fiber simulation results show that the rheological properties of flexible fiber suspension are highly dependent on the microstructural characteristics of the suspension. It is shown that fiber stiffness (bending ratio BR) has strong impact on the suspension rheology in the range BR < 3. The relative viscosity of the fiber suspension under shear increases significantly as BR decreases. Direct numerical simulation of flexible fiber suspension allows computation of the primary normal stress difference as a function of BR. These results show that the primary normal stress difference has a minimum value at BR ∼ 1. The primary normal stress differences for slightly deformable fibers reaches a minimum and increases significantly as BR decreases below 1. The results are explained based on the Batchelor's relation for non-Brownian suspensions. The influence of fiber stiffness on the fiber orientation distribution and orbit constant is the major contributor to the variation in rheological properties. A least-squares curve-fitting relation for the relative viscosity is obtained for flexible fiber suspension. This relation can be used to predict the relative viscosity of flexible fiber suspension based on the result of rigid fiber suspension. The unique capability of the LBM-EBF method for sub-grid resolution and multiscale analysis of particle suspension is applied to the challenging problem of platelet motion in blood flow. By computing the stress distribution over the platelet, the "blood damage index" is computed and compared with experiments in channels with various geometries [43]. In platelet simulation, the effect of 3D channel geometry on the platelet activation and aggregation is modeled by using LBM-EBF method. Comparison of our simulations with Fallon's experiments [43] shows a similar pattern, and shows that Dumont's BDI model [40] is more appropriate for blood damage investigation. It has been shown that channels with sharp transition geometry will have larger recirculation areas with high BDI values. By investigating the effect of hinge area geometry on BDI value, we intend to use this multiscale computational method to optimize the design of Bileaflet mechanical heart valves. Both fiber simulations and platelet simulations have shown that the novel LBM-EBF method is more efficient and stable compare to the conventional numerical methods. The new EBF method is a two-Cway coupling method with sub-grid accuracy which makes the platelet simulations possible. The LBM-EBF is the only method to date, to the best of author's knowledge, that can simulate suspensions with large number of deformable particles under complex flow conditions. It is hoped that future researchers may benefit from this new method and the algorithms developed here.

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Dissertations / Theses on the topic 'Suspensions, chemistry'

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