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Preuss, Frida, Julia Asp, Sofia Larsson, and Stephanie Kylington. "Separation of Nanoporous Silica Particles." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277106.
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In this study a sample of particles in a size region of 0.05-10 μm were run through a centrifugation process with the ambition to make it monodisperse. The product requirements were stated as follows, particles within the size range of 2 to 3.8 μm should be isolated and separated from the sample with a D90/D10 < 1.4 where the D90/D50/D10 values should be approximately 3.8 μm/2.5 μm/2 μm. It was found that two layers of sucrose with a 50/50 volume distribution of 45w% sucrose solution and 60w% sucrose solution respectively, was the most efficient density gradient arrangement for separation of this particular sample. The optimal time and RPM combination was found to be 5 min 3000 RPM with a fast acceleration and slower deceleration, ratio 9:6. Two centrifugation rounds on the same sample improved D90/D10 drastically. The effect of centrifugation rounds on D90/D10 was not investigated further than 3 rounds, however this would be a good starting point for further studies. The upscaled test runs indicated a positive result, i.e. the yields with respect to both mass and purity were reproducible. It is worth mentioning that the upscale was only in the volume, sample load volume and surface area factors. The gradient height or particle travel distance remained the same.
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Yunus, Md Nurul Amziah. "Continuous dielectrophoretic separation of colloidal particles." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/79370/.
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Dielectrophoresis (DEP) is a technique that can be used to separate particle at microscale. It is of particular interest because it is a non-invasive, non-destructive and non-contact technique, which ensures that sample composition remains the same with only the particles being separated. On the microscale, DEP has been used to separate viable and non-viable cells, and cells with different dielectric properties, with the aid of a range of miniaturised, microfabricated devices. However, DEP at the nano-scale is a novel area and is still under research. Miniaturisation of devices in general has been an ongoing trend to improve the performance of analytical tools. In particular, processes for micro-device fabrication using dry film resist have been studied in order to reduce size, cost, sophisticated hardware usage and power consumption. This thesis presents an investigation into the novel design of dielectrophoretic particle separator, using rapid dry film resist methods to construct an integrated device. The development of analysis software for detecting particle movement in videos of experiments is presented, along with its use as a data analysis tool for determining particle position in the array. Characterisation measurements have been performed for a range of experimental parameters demonstrating the variability and behaviour of the device. Separation experiments were performed using test micron and submicron particles over a wide range of applied field frequencies, confirming the theoretical predictions and demonstrate the standard of separation efficiency. Preliminary investigations of other application of the device to larger particle and integrating micropump technology are also presented.
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Das, Subhankar. "Electrostatic charging and separation of fine particles." Poitiers, 2007. http://www.theses.fr/2007POIT2299.
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L’objectif de ce travail a été double : améliorer la connaissance des facteurs qui influencent les processus de charge des particules < 1 mm et proposer desProcédés innovants pour la séparation des mélanges de matériaux pulvérulents fins. La méthodologie des plans d’expérience a été utilisée pour la modélisation du processus de charge triboélectrique de poudres dans des dispositifs pneumatiques. En utilisant la charge en champ couronne, il a été possible de mettre au point, un procédé destiné au recyclage des cendres issues des centrales thermoélectriques à charbon. La compréhension des phénomènes en jeu a été améliorée par la simulation numérique des trajectoires des particules. L’induction Electrostatique est le troisième mécanisme de charge dont l’efficacité a été prouvée expérimentalement. En Conclusion : le développement de nouveaux procédés de séparation pour des particules fines implique le choix du mécanisme de charge et du système d’électrodes les plus appropriés.
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You, Yuan. "Liquid-liquid phase separation in atmospherically relevant particles." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50466.
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Aerosol particles containing both organic material and inorganic salts are abundant in the atmosphere. These particles may undergo phase transitions when the relative humidity fluctuates between high and low values in the atmosphere. This dissertation focuses on liquid-liquid phase separation in atmospherically relevant mixed organic-inorganic salt particles. Liquid-liquid phase separation has potentially important implications in chemical and physical processes in the atmosphere. A humidity and temperature controlled flow cell coupled to either an optical, fluorescence, or Raman microscope was used to study the occurrence of liquid-liquid phase separation and the phase separation relative humidity (SRH) of particles containing atmospherically relevant organic species mixed with inorganic salts. Organic species in the particles studied include single organic species, such as carboxylic acids, alcohols, and oxidized aromatic compounds, as well as complex laboratory-produced secondary organic material. Material directly collected from the atmospheric environment was also studied. In this dissertation, the effects of oxygen-to-carbon elemental ratio (O:C) of the organic species, salt types, molecular weight of the organic species, and temperature on the occurrence of liquid-liquid phase separation and SRH were studies. The oxygenic-to-carbon elemental ratio was a useful parameter for predicting liquid-liquid phase separation and SRH. Liquid-liquid phase separation did not depend strongly on the molecular weight of the organic species or temperature. The correlation between SRH and O:C in particles containing organic species mixed with different salts were qualitatively similar. Results of this research will help improve the understanding of liquid-liquid phase separation in the atmospheric aerosols, and may, in turn, improve simulations and predictions of atmospheric chemistry and climate. Supplementary materials: http://hdl.handle.net/2429/50970Science, Faculty of
Chemistry, Department of
Graduate
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Jackson, George. "Phase separation in solutions of large spherical particles." Thesis, University of Oxford, 1986. http://ora.ox.ac.uk/objects/uuid:9db7de2e-b365-4433-8e14-746efb32c070.
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The effect of large size ratios of solute to solvent on the critical properties and phase behaviour of binary mixtures of spherical particles is investigated using an "augmented van der Waals" equation of state. The equation used is essentially a van der Waals equation with an improved hard sphere repulsive term. Molecular dynamics and constant-pressure Monte Carlo simulations of binary mixtures of hard spheres with different diameter ratios and mole fractions are undertaken to check the adequacy of the hard sphere equation. Good agreement is found, even for systems with large differences in size. Furthermore, many of the hard sphere mixtures exhibited a transition from a fluid to a solid phase at high densities. Phase boundaries are calculated for model mixtures comprising spheres of different sizes between which there are long-ranged attractive forces. Particular attention is paid to the case in which the ratio of sizes is infinite. The systems show a wide variety of behaviour that includes liquid-liquid and gas-gas immiscibility, and the formation of negative azeotropes. Calculations investigating the effect of different attractive interactions between the small and large spheres show that as the magnitude of this interaction is increased, liquid-liquid immiscibility becomes the dominant feature of the phase diagram at moderate temperatures. The extent of liquid-liquid coexistence is greatest at large size differences. These model systems are shown to reproduce some of the behaviour of aqueous solutions of surfactants if it is assumed that the large spheres are models of the micelles and the small spheres models of the solvent molecules. The properties of binary lattice mixtures of bifunctional molecules whose ends are chosen to mimic surfactant and solvent molecules are also briefly investigated, to determine the effect of the asymmetric surfactant molecule on the phase separation. Closed-loops emerge in the phase diagrams as the surfactant character of one of the species is increased.
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Imani, Jajarmi Ramin. "Acoustic separation of submicron particles in gaseous flows." Licentiate thesis, KTH, Mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-167629.
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The separation of submicron particles suspended in gaseous flows is a problem of great importance and is the subject of sustained research efforts. This is motivated by several challenges presented by modern science and technology requiring high separation efficiencies for submicron particles.Continuous acoustic particles separation is a novel technique based on the acoustophoresis phenomenon, in which a particle within an acoustic field is manipulated using acoustic forces on its surface. This technique has the potential to overcome some of the limitations of common techniques for the separation of submicron particles, as well as performing advanced tasks such as sorting particles according to their size or density.In this thesis, the separation of submicron solid particles suspended in air is investigated experimentally, with a focus on the effect of key design parameters (acoustic, flow, geometry) on the efficiency of the process. A simple method based on laser light scattering was also used to provide qualitative information on the particle number density as a function of position in the channel. This technique allowed to quickly investigate the effect of a wide range of parameters on the acoustic separation efficiency including the pressure amplitude, the frequency of the standing wave, the average flow velocity and the parallelism of the channel walls. The results demonstrate conclusively that acoustic manipulation is possible for submicron particles and that the acoustic force scales following the trends expected from theoretical models developed in the continuum regime. From the size of the particles used it however follows that the observed separation is the result of transition regime acoustophoresis, with a Knudsen number on the order of 0.2.QC 20150522
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Kejík, Pavel. "Low-Cost Filtration Barriers for Ultrafine Particles Separation." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401605.
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V mnoha oborech jsou stále využívána anorganická filtrační media založená na materiálech, jejichž výroba využívá primární suroviny. Jejich výroba je tedy energeticky náročná a v důsledku nákladná a neohleduplná k životnímu prostředí. Cílem této práce je ověřit možnost využití alkalicky aktivovaných materiálů na bázi sekundárních surovin, především vysokopecních strusek (BFS) a popílků z uhelných elektráren (FA), pro výrobu porézních médií schopných v budoucnosti nahradit keramické a jiné anorganické filtry. Výzkum je rozvinut skrze experimentální design založený na výpočetním schématu samostatně vyvinutém s pomocí programu MATLAB. Toto schéma počítá vhodná složení směsí na základě poměrů obsahu nejdůležitějších oxidů ve vstupních surovinách. Tak je zajištěno zohlednění proměnlivého složení vstupních surovin a práce je tím hodnotnější, že její výsledky jsou skrze početní nástroj zohledňující základní oxidové složení surovin zobecnitelné. Zároveň byly však pro srovnání a lepší názornost závislostí vlastností na složení navrhnuty a připraveny i série vzorků založené vždy pouze na jedné ze surovin. Z výsledků vyplývá, že pevnost vzorků z těchto směsí (vytvrzených 24 hodin při 70 °C) ve čtyřbodové ohybové zkoušce dle ČSN EN 12390 5 může přesáhnout 7,6 MPa. Dosažením co možná nejvyšší porozity však zákonitě negativně ovlivňuje pevnost materiálu a výsledný materiál tedy dosahuje pevnosti těsně nad hranicí 6,3 MPa. Výsledky obecně dokazují, že nejvíce je pevnost materiálů ovlivněna poměrem SiO2/Al2O3 a množstvím alkalického aktivátoru. Z výsledků vyplývá, že alkalicky aktivované materiály (AAM) na bázi strusky dosahují i více než dvojnásobné pevnosti analogických materiálů na bázi elektrárenského popílku. Velikost pórů materiálů připravených z tříděných surovin s velikostí zrna od desítek po lehce přes sto mikronů se ve většině případů pohybuje v rozmezí desetin ž jednotek mikronů, v případě výsledného materiálu je to pak přibližně 0,2 mikronu. Celková porozita lisovaných těles se pohybuje těsně pod 40 %, což je v tomto případě téměř dvojnásobek ve srovnání s totožnými materiály na bázi netříděných surovin. Výsledky rovněž ukazují, že materiály na bázi strusky vykazují nižší porozitu než ty na bázi popílku, což je patrně způsobeno rozdílnou morfologií částic obou materiálů – částice strusky jsou nepravidelně hranaté a částice popílku kulaté. V průběhu experimentální činnosti byla pozorována tvorba výkvětů u materiálů na bázi elektrárenských popílků. Pomocí Energo-disperzní spektroskopické analýzy (EDS) byly výkvěty identifikovány jako hydroxid sodný procházející karbonatací za účasti vzdušného CO2. Test permeability vyžadoval, kvůli velmi jemné povaze porézní struktury, přípravu asymetrických filtračních přepážek. Tyto přepážky dosáhli propustnosti 138 L/h.m2.bar pro vodu a 1320 L/h.m2.bar pro vzduch.
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Woodside, Steven Murray. "Spatial distribution of acoustic forces on particles : implications for particle separation and resonator design." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0007/NQ34646.pdf.
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Schaap, Allison Schaap. "Transport and size-separation of airborne particles in a microchannel for continuous particle monitoring." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/30230.
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Microfluidics research and development has emerged as a novel and promising tool for the development of sensors and actuators. However, one area in which microfluidics has been only minimally employed is in the handling of airborne particles, or aerosols. The real-time monitoring of aerosols is important for protecting human health and earth’s environment. The small size of microchannels, coupled with the opportunity to integrate sensing technologies, suggests them as a promising tool for the next generation of aerosol sensors. To that end, this thesis presents a microfluidics-based system for the size-separation of aerosols. Specifically, centrifugal force is exerted on each particle as it travels around a curved microchannel, resulting in the particle occupying a size-dependent lateral position in the channel.
The behaviours of aerosols in a microchannel are examined, including the effects of flow focusing, the diffusion of airborne particles in a channel, and the centrifugal and viscous forces exerted on particles in a curved microchannel. Mathematical descriptions and computer simulations of these effects are developed to model these effects. Straight and curved microchannels were fabricated and each of these effects was measured experimentally, and compared to the models. Various combinations of airborne particles between 0.2 µm and 3.2 µm were successfully separated by size. A prototype optical particle detector was built and tested for its suitability as a candidate for integration with the microchannel particle separator.
This represents the first approach in which aerosols have been separated by centrifugal forces in a microchannel, and one of very few approaches that have been used for any kind of size-based separation of airborne particles in microchannels. The small footprint and potential for integration offered by microsystem fabrication technology make it a desirable avenue of pursuit for the development of small, portable particulate monitors. The results presented here confirm that this approach to size-separation is a feasible option for a future microsystem based size-selective particulate monitor.
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Goodluck, Olufemi W. (Olufemi Waheed). "Magnetic separation of strongly magnetic particles using alternating field." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65920.
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Kukunoor, Nagesh Sri. "Separation of ultrafines in dispersions using electrocoagulation." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/11755.
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Yuan, Huixin. "Hydrocyclones for the separation of yeast and protein particles." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242214.
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Chatterjee, Arpita. "Size-Dependant Separation of Multiple Particles in Spiral Microchannels." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1312480517.
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Kassaee, Mohamad Hadi. "Internal surface modification of zeolite MFI particles and membranes for gas separation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44906.
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Zeolites are a well-known class of crystalline oxide materials with tunable compositions and nanoporous structures, and have been used extensively in catalysis, adsorption, and ion exchange. The zeolite MFI is one of the well-studied zeolites because it has a pore size and structure suitable for separation or chemical conversion of many industrially important molecules. Modification of zeolite structures with organic groups offers a potential new way to change their properties of zeolites, beyond the manipulation of the zeolite framework structure and composition.
The main goals of this thesis research are to study the organic-modification of the MFI pore structure, and to assess the effects of such modification on the adsorption and transport properties of zeolite MFI sorbents and membranes. In this work, the internal pore structure of MFI zeolite particles and membranes has been modified by direct covalent condensation or chemical complexation of different organic molecules with the silanol defect sites existing in the MFI structure. The organic molecules used for pore modification are 1-butanol, 1-hexanol, 3-amino-1-propanol, 1-propaneamine, 1,3-diaminopropane, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. TGA/DSC and 13C/29Si NMR characterizations indicated that the functional groups were chemically bound to the zeolite framework, and that the loading was commensurate with the concentration of internal silanol defects. Gas adsorption isotherms of CO2, CH4, and N2 on the modified zeolite materials show a range of properties different from that of the bare MFI zeolite. The MFI/3-amino-1-propanol, MFI/2-[(2-aminoethyl)amino]ethanol, and MFI/benzenemethanol materials showed the largest differences from bare MFI. These properties were qualitatively explained by the known affinity of amino- and hydroxyl groups for CO2, and of the phenyl group for CH4. The combined influence of adsorption and diffusion changes due to modification can be studied by measuring permeation of different gases on modified MFI membranes.
To study these effects, I synthesized MFI membranes with [h0h] out-of-plane orientation on α-alumina supports. The membranes were modified by the same procedures as used for MFI particles and with 1-butanol, 3-amino-1-propanol, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. The existence of functional groups in the pores of the zeolite was confirmed by PA-FTIR measurements. Permeation measurements of H2, N2, CO2, CH4, and SF6, were performed at room temperature before and after modification. Permeation of n-butane, and i-butane were measured before and after modification with 1-butanol. For all of the studied gases, gas permeances decreased by 1-2 orders of magnitude compared to bare MFI membranes for modified membranes. This is a strong indication that the organic species in the MFI framework are interacting with or blocking the gas molecule transport through the MFI pores.
A detailed fundamental study of the CO2 adsorption mechanism in modified zeolites is necessary to gain a better understating of the adsorption and permeation behavior of such materials. Towards this end, an in situ FTIR study was performe.For the organic molecules with only one functional group (1-butanol, benzenemethanol, and 1-propaneamine), physical adsorption was found - as intuitively expected - to be the only observed mode of attachment of CO2 to the modified zeolite material. Even in the case of MFI modified with 1,3-diaminopropane, only physical adsorption is seen. This is explained by the isolated nature of the amine groups in the material, due to which only a single amine group can interact with a CO2 molecule. On the other hand, chemisorbed CO2 species are clearly observed on bare MFI, and on MFI modified with 3-amino-1-propanol or 2-[(2-aminoethyl)amino]ethanol. Specifically, these are carbonate-like species that arise from the chemisorption of CO2 to the silanol group in bare MFI and the alcohol groups of the modifying molecule. The possibility of significant contributions from external surface silanol groups in adsorbing CO2 chemisorbed species was ruled out by a comparative examination of the FTIR spectra of 10 μm and 900 nm MFI particles modified with 2-[(2-aminoethyl)amino]ethanol.
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Akhtar, Haroon. "Development of a small separation riser for fine coal particles." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4466.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains ix, 81 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 68-69).
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Ooe, Katsutoshi, and Toshio Fukuda. "Development of micro particles separation device with piezo-ceramic vibrator." IEEE, 2009. http://hdl.handle.net/2237/13949.
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Slack, Michael David. "Separation of particles from liquids by the solid core cyclone." Thesis, University of Newcastle Upon Tyne, 1997. http://hdl.handle.net/10443/750.
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A computational and physical modelling study is made of the removal of inclusions from liquid steel by use of a novel form of hydrocyclone in which a solid conical core that replaces the conventional vortex finder acts as a guide to the spiralling liquid flow and acts also as a capture surface for disentrained inclusions. In preliminary investigations, an inviscid computational model is derived that is found to be effective in outlining the general behaviour of specific hydrocyclone flows when tested against published experimental results. The more generally applicable commercial CFD code Fluent is likewise tested, from which it is shown that, among the turbulence models available, the anisotropic turbulence typical of spiralling hydrocyclone flows requires a form of Reynolds stress model for effective computation. The conventional k-c model is found to be misleading. On this basis, mathematical modelling and optimal computational design of hydrocyclones containing an axial conical solid core show that the separation efficiency of the cyclone is profoundly enhanced by the presence of a core, and that by use of a particle tracking model effective centripetal migration of inclusion particles in steel will occur towards the core. Experiments with a water model of computed optimal cyclone designs provided effective validation of the numerical study. Photographically active particles of neutral density were tracked by a novel stroboscopic technique which permitted bi-directional observation revealing instantaneous velocity, spatial position and spiral angle. Using populations of low density particles having the same spectrum of Stokes velocity as inclusions in the size range 35 to 150 microns found typically in liquid steel, sampling by Coulter counter showed that effective separation to the core surface of particles down to an equivalent size of 30 microns was achieved. In a final step, a pilot cyclone design for use with steel was established and water model tests at full scale showed that stable cyclone flow and discharge are achievable with gravity feed to the cyclone.
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Zulqarnain, Kamran. "Scale-up of affinity separation based on magnetic support particles." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313426.
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Park, Edward S. 1974. "Microfabricated magnetophoretic focusing systems for the separation of submicrometer particles." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32268.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Includes bibliographical references.
Magnetic separation is an actively researched field due to its broad applicability to the mineral, chemical, and biological industries. The objective of this work was to design, fabricate, and test systems to study magnetophoresis of particles in suspension. To achieve this goal, two system concepts were developed: an Alternating Field System and a Flow System. Both systems consisted of permanent magnets and miniaturized devices (separation chips), which integrated microfluidic channels with ferromagnetic core elements. The systems produced "sawtooth" magnetic fields that were combined with a long-range magnetic field or pressure- driven flow to bring about migration, focusing and trapping of nonmagnetic particles suspended in ferrofluid. A potential application of such systems is high-resolution, size-based separation of DNA, cellular organelles, viruses, and other like-sized biological entities. The systems were designed using finite element analysis and fabricated using IC/MEMS microfabrication techniques. The fabrication process for the separation chips realized a microfluidic channel and electroplating molds in a single layer of SU-8 photoresist on a glass substrate. Nickel core elements were electroplated into the molds, and a PDMS cover substrate was attached using a novel technique involving contact bond and heat cycling. The systems were tested via experiments using optical fluorescence methods to observe the concentration profiles of polydisperse suspensions of polystyrene beads.
(cont.) Alternating Field System involved simple migration under a long-range magnetic field, focusing under a sawtooth magnetic field, and attempted separation by combining the long-range and sawtooth fields. The most significant findings of the trials were the significant effect of particle- particle interactions and high sensitivity to the core design of the chip. The Flow System trials combined a sawtooth field with flow. The trials demonstrated size-based trapping of particles, where 840 nm beads were trapped earlier along a separation channel, while 510 nm beads were trapped further along. Moreover, the location along the channel at which particles of a given size were trapped was shown to be a function of flow rate. Size-based trapping in magnetic potential wells, as well as flow rate tuning, could form the basis of a high-resolution particle separation system.
by Edward S. Park.
S.M.
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Li, Biao. "Hydrophobic-Hydrophilic Separation Process for the Recovery of Ultrafine Particles." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/103278.
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The demands for copper and rare earth elements (REEs) in the U.S. will keep rising due to their applications in green energy technologies. Meanwhile, copper production in the U.S. has been declining over the past five years due to the depletion of high-grade ore deposits. The situation for REEs is worse; there is no domestic supply chain of REEs in the U.S. since the demise of Molycorp, Inc. in 2016. Studies have shown that the rejected materials from copper and coal processing plants contain significant amounts of valuable metals. As such, this rejected material can be considered as potential secondary sources for extracting copper and REEs, which may help combat future supply risks for the supply of copper and REEs in the U.S. However, the valuable mineral particles in these resources are ultrafine in size, which poses considerable challenges to the most widely used fine particle beneficiation technique, i.e., froth flotation. A novel technology called the Hydrophobic-Hydrophilic Separation (HHS) process, developed at Virginia Tech, has been successfully applied to recover fine coal in previous research. The results of research into the HHS process showed that the process has no lower particle size limit, similar to solvent extraction. Therefore, the primary objective of this research is to explore the feasibility of using the new process to recover ultrafine particles of coal, copper minerals, and rare earth minerals (REMs) associated with coal byproducts.
In the present work, a series of laboratory-scale oil agglomeration and HHS tests have been carried out on coal with the objectives of assisting the HHS tests in pilot-scale, and the scale-up of the process. The knowledge gained from this study was successfully applied to solving the problems encountered in the pilot-scale tests. Additionally, a new and more efficient equipment known as the Morganizer has been designed and constructed to break up the agglomerates in oil phase as a means to remove entrained gangue minerals and water. The effectiveness of the new Morganizers has been demonstrated in laboratory-scale HHS tests, which may potentially result in the reduction of capital costs in commercializing the HHS process. Furthermore, the prospect of using the HHS process for processing high-sulfur coals has been explored. The results of this study showed that the HHS process can be used to increase the production of cleaner coal from waste streams.
Application of the HHS process was further extended to recover the micron-sized REMs from a thickener underflow sample from the LW coal preparation plant, Kentucky. The results showed that the HHS process was far superior to the forced-air flotation process. In one test conducted during the earlier stages of the present study, a concentrate assaying 17,590 ppm total REEs was obtained from a 300 ppm feed. In this test, the Morganizer was not used to upgrade the rougher concentrate due to the lack of proper understanding of the fundamental mechanisms involved in converting oil-in-water (o/w) Pickering emulsions to water-in-oil (w/o) Pickering emulsions. Many of the studies has, therefore, been focused on the studies of phase inversion mechanisms. The results showed that phase inversion requires that i) the oil contact angles (θo) of the particles be increased above 90o, ii) the phase volume of oil (ϕo) be increased, and iii) the o/w emulsion be subjected to a high-shear agitation. It has been found that the first criterion can be readily met by using a hydrophobicity-enhancing agent. These findings were applied to produce high-grade REM concentrates from an artificial mixture of micron-sized monazite and silica.
Based on the improved understanding of phase inversion, a modified HHS process has been developed to recover ultrafine particles of copper minerals. After successfully demonstrating the efficacy and effectiveness of this process on a series of artificial copper ore samples, the modified HHS process was used to produce high-grade copper concentrates from a series of cleaner scavenger tails obtained from operating plants.Doctor of Philosophy
Recovery and dewatering of ultrafine particles have been the major challenges in the minerals and coal industries. Based on the thermodynamic advantage that oil droplets form contact angles about twice as large as those obtainable with air bubbles, a novel separation technology called the hydrophobic-hydrophilic separation (HHS) process was developed at Virginia Tech to address this issues. The research into the HHS process previously was only conducted on the recovery of ultrafine coal particles; also, the fundamental aspects of the HHS process were not fully understood, particularly the mechanisms of phase inversion of oil-in-water emulsions to water-in-oil emulsions. As a follow-up to the previous studies, emulsification tests have been conducted using ultrafine silica and chalcopyrite particles as emulsifiers, and the results showed that phase inversion requires high contact angles, high phase volumes, and high-shear agitation. These findings were applied to improve the HHS process for the recovery of ultrafine particles of coal, copper minerals, and rare earth minerals (REMs). The results obtained in the present work show that the HHS process can be used to efficiently recover and dewater fine particles without no lower particle size limits.
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Chhabria, Deepika. "ELECTROSTATIC SEPARATION OF SUPERCONDUCTING PARTICLES FROM NON-SUPERCONDUCTING PARTICLES AND IMPROVEMENT IN FUEL ATOMIZATION BY ELECTRORHEOLOGY." Diss., Temple University Libraries, 2009. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/33116.
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PhysicsPh.D.
This thesis has two major topics: (1) Electrostatic Separation of Superconducting Particles from a Mixture of Non-Superconducting Particles. (2) Improvement in fuel atomization by Electrorheology. (1) Based on the basic science research, the interactions between electric field and superconductors, we have developed a new technology, which can separate superconducting granular particles from their mixture with non-superconducting particles. The electric-field induced formation of superconducting balls is important aspect of the interaction between superconducting particles and electric field. When the applied electric field exceeds a critical value, the induced positive surface energy on the superconducting particles forces them to aggregate into balls or cling to the electrodes. In fabrication of superconducting materials, especially HTSC materials, it is common to come across materials with multiple phases: some grains are in superconducting state while the others are not. Our technology is proven to be very useful in separating superconducting grains from the rest non-superconducting materials. To separate superconducting particles from normal conducting particles, we apply a suitable strong electric field. The superconducting particles cling to the electrodes, while normal conducting particles bounce between the electrodes. The superconducting particles could then be collected from the electrodes. To separate superconducting particles from insulating ones, we apply a moderate electric field to force insulating particles to the electrodes to form short chains while the superconducting particles are collected from the middle of capacitor. The importance of this technology is evidenced by the unsuccessful efforts to utilize the Meissner effect to separate superconducting particles from non-superconducting ones. Because the Meissner effect is proportional to the particle volume, it has been found that the Meissner effect is not useful when the superconducting particles are smaller than 45pm. One always come across multi-phase superconducting materials where most superconducting grains are much smaller than 45μm. On the other hand, since our technology is based on the surface effect, it gets stronger when the particles become smaller. Our technology is thus perfect for small superconducting particles and for fabrication of HTSC materials. The area of superconductivity is expected to be very important for 21st Century energy industry. The key for this development is the HTSC materials. We, therefore, expect that our technology will have strong impact in the area. (2) Improving engine efficiency and reducing pollutant emissions are extremely important. Here we report our fuel injection technology based on new physics principle that proper application of electrorheology can reduce the viscosity of petroleum fuels. A small device is thus introduced just before the fuel injection for the engine, producing a strong electric field to reduce the fuel viscosity, resulting in much smaller fuel droplets in atomization. As combustion starts at the interface between fuel and air and most harmful emissions are coming from incomplete burning, reducing the size of fuel droplets would increase the total surface area to start burning, leading to a cleaner and more efficient engine. This concept has been widely accepted as the discussions about future engine for efficient and clean combustion are focused on ultra-dilute mixtures at extremely high pressure to produce much finer mist of fuel for combustion. The technology is expected to have broad applications, applicable to current internal combustion engines and future engines as well.
Temple University--Theses
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Imani, Jajarmi Ramin. "Acoustic separation and electrostatic sampling of submicron particles suspended in air." Doctoral thesis, KTH, Strömningsfysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196857.
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We investigate experimentally the effects of acoustic forces on submicron aerosol in a channel flow. This technique can potentially overcome some of the limitations of conventional separation systems and provide advanced manipulation capabilities such as sorting according to size or density. The theoretical framework for acoustophoresis at such small length scales where molecular effects are expected to be significant is still incomplete and in need of experimental validation. The main objectives of this thesis are to identify the physical limitations and capabilities of acoustophoretic manipulation for submicron aerosol particles. Two sets of experiments were carried out: first, qualitative results revealed that acoustic manipulation is possible for submicron particles in air and that the acoustic force follows the trend expected by theoretical models developed for particles in inviscid fluids. The acoustic force on submicron particles was estimated in a second set of measurements performed with quantitative diagnostic tools. Comparison of these results with available theoretical models for the acoustic radiation forces demonstrates that for such small particles additional forces have to be considered. At submicron length scales, the magnitude of the forces observed is orders of magnitude higher than the predictions from the inviscid theory. One potential application for acoustophoresis is specifically investigated in this thesis: assist electrostatic precipitation (ESP) samplers to target very small aerosols, such as those carrying airborne viruses. To identify the shortcomings of ESP samplers that acoustophoresis should overcome, two ESP designs have been investigated to quantify capture efficiency as a function of the particle size and of the air velocity in a wind tunnel. The results reveal that both designs have limitations when it comes to sampling submicron aerosol particles. When exposed to polydispersed suspensions they behave as low-pass filters.QC 20161125
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Blackburn, Clive de Warrenne. "The separation and detection of Salmonella from foods using immunomagnetic particles." Thesis, University of Surrey, 1991. http://epubs.surrey.ac.uk/1005/.
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Tarrant, Lee. "A study of high gradient magnetic separation of strongly magnetic particles." Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265394.
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Guzman, Francisco J. "Separation of Colloidal Particles in a Packed Column using Depletion Forces." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/34831.
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Depletion forces were used to separate an equinumber density binary dispersion of 1.5 and 0.82 µm polystyrene sulfate (PS) particles. Experiments consisted of injecting a pulse of a binary dispersion of PS particles into the inlet of a packed bed of 0.5 mm silica collector beads. Prior to injection, a carrier fluid of either KCl and KOH electrolyte or a silica nanoparticle dispersion was flowing through the column at steady state. When the carrier fluid was a dispersion of silica nanoparticles, the ratio of PS particles in the column outlet would change from 1:1 big to small particles to slightly over 2:1. This implies that more of the smaller 0.82 µm particles were being trapped on the surface of the collector beads due to depletion forces. Experiments with a single particle type (either 1.5 or 0.82 µm PS particle) were also done and correlated with the binary dispersion measurements. Potential energy profiles between a PS particle and a flat silica plate were calculated. The secondary energy barrier for the 1.5 µm particles was two times greater than for the 0.82 µm particles. Hence, the 0.82 µm particles were more likely to overcome the energy barrier and get trapped on the surface of the collector beads. Although the potential energy profiles were calculated at equilibrium, they can be used as a tool in finding the optimal conditions for separation.Master of Science
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Karpul, David. "Limiting factors in acoustic density separation of carbon particles in air." Thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/5195.
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Particles suspended in a fluid that is exposed to an acoustic standing wave experience a time-averaged force that drives them to either the pressure nodes or anti-nodes of the wave. Several filter designs have been successfully implemented using this force to filter small particles in liquids with low flow rates and small cross-sectional areas. It has been suggested that the filtration of small solid particles out of a gas, such as carbon in air (smoke), would be a possible application of acoustic density separation. The emissions created by the combustion of hydrocarbons used in industrial processes, electricity production and transport significantly damage human health and the world at large. Particulate matter released, primarily by power plants, is currently removed from the emissions by highly space consuming and expensive equipment. The creation of a new type of particulate filter, which is both more cost effective and less space consuming, would be beneficial to the industry and consequently the environment at large. This study shows the limiting factors, in both power requirements and design factors, of an acoustic filter designed for filtering smoke particles across large cross-sectional areas at high flow rates, as in the case of an industrial smoke stack. It is shown that while filtration is possible, the power needed is impractical. It is also shown that operating the filter above a particular threshold intensity the energy usage of the filter is optimised.
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Rahman, Md Mahbubor. "Preparation of Temperature Responsive Magnetic Polymer Particles for Nucleic Acid (DNA/RNA) Separation." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10253.
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Le problème dans le diagnostique biomédical réside non seulement dans les outils de détections mais aussi dans la préparation des échantillons qui nécessitent impérativement un prés traitement. Ce prétraitement consiste à libérer le matériel nucléique (ADN/ ARN) dans le milieu et le capturer et le purifier par la suite avant les étapes d'amplification et de détection. Ainsi, l'utilisation de nanoparticules de latex magnétiques stimulables permettra non seulement d'augmenter la sensibilité de certains testes, mais aussi une possible utilisation dans des automates ou intégration dans des microsystèmes ou la rapidité de séparation magnétiques. Ainsi, l'objectif de cette étude est d'élaborer de particules de latex magnétiques stimulables pour le transport des acides nucléiques. Des émulsions magnétiques (huile magnétique/eau) sont encapsulées par polymérisation radicalaire en milieu dispersé. La polymérisation est réalisée en réacteur fermé en utilisant le persulfate de potassium comme amorceur (KPS), un mélange de monomères styrène 60%/DVB 40% ou DVB. L'optimisation de ces deux formulations permet l'obtention de particules parfaitement coeur-écorce. L'utilisation de ces particules magnétiques semences de polymérisation par précipitation a permet l'obtention de particules magnétiques cationiques et thermosensibles. L'utilisation d'un agent de réticulation est indispensable à l'obtention d'une écorce sensible à la température et l'utilisation d'un monomère aminé (AEMH) et un amorceur cationique (V50) sont indispensables pour l'obtention de particules de latex magnétiques cationiques (amine et amidine en surface). L'évaluation de ces particules lors de la capture des acides nucléiques a montré une influence marquée de la température d'analyse sur le pourcentage d'adsorption et de désorption. Ces valeurs sont plus élevées pour l'adsorption à 18°C et pour la désorption à 40°C. La synthèse de particules de latex magnétiques fonctionnalisées par l'acide phenyl boronique a été réalisée en utilisant le NIPAM, le MBA et l'APB. Les particules obtenues sont sensibles à la température et ai glucose. Des particules thermosensibles carboxyliques via l'acide acrymique (AA) ont été fonctionnalisée par greffage chimique en utilisant l'amino acide pheny boronique. Les deux types de particules montrent une sensibilité à la température et également au glucose. La fixation spécifique de l'ARN a été examiné et la tendance des résultats montre une immobilisation sensible au pH et la températureThe use of nucleic acid (DNA/RNA) as a diagnostic and therapeutic molecule has become promising in biomedical field. The particles having magnetic and temperature responsive property could be of great interest for better use in controlled switching nucleic acid separation, purification and concentrating. The aim of this work is to prepare functionalized temperature responsive magnetic polymer particles and to use them as efficient solid support for the extraction of nucleic acids (DNA/RNA) from any biological sample. Here, we report amine (NH2) and boronic acid [-B(OH)2] functionalized temperature responsive magnetic polymer particles synthesis, characterization and application in nucleic acid separation. Divinylbenzene (DVB) cross-linked magnetic polystyrene (PSt) particles were prepared first by seed emulsion polymerization of DVB and St in the presence of oil-in-water (o/w) magnetic emulsion. Thereafter, DVB cross-linked magnetic polystyrene particles were functionalized by the seed precipitation polymerization of N-isopropylacrylamide (NIPAm) with either of the functional monomer aminoethylmethacrylate hydrochloride (AEMH), vinylphenylboronic acid (VPBA) or acrylic acid (AA).Moreover, aminophenylboronic acid (APBA) were grafted onto carboxylic acid functionalized temperature responsive magnetic particles. All of the prepared magnetic particles were successfully characterized to obtain the morphology, surface functionality, chemical composition, colloidal properties in terms of size and zeta potential and magnetic property of the particles. Importantly, size shrinkage upon heating attests temperature responsiveness of magnetic polymer particle. Further investigation revealed that only amine or boronic acid group containing magnetic polymer particles are able to separate nucleic acid. Interestingly, RNA adsorption is strongly occurred than that of DNA onto boronic acid magnetic polymer particles due to the opportunity of boronate ester formation with cis-diol of RNA. The prepare temperature magnetic polymer particles would be a potential candidate to develop an automated microsystem device for nucleic acid separation
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Barr, Giles David. "The separation of signals and background in a nucleon decay experiment." Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:f06155db-aa60-46dc-8d56-7ee55921e2ff.
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Two aspects of the problems encountered in searching for nucleon decay in the Soudan 2 detector are discussed. The types of event which are expected are discussed. The most common are Induced by gamma rays from the naturally occurring radioactive isotopes in the cavern rock. A calculation has been developed to predict the rates of such events in the detector and the results agree well when compared with measurements made underground. Some radioactive events cause Compton scattering in the wireplane region of the detector and prohibit the use of a simple multiplicity trigger. Such events have been studied. An electronic trigger system has been designed which will achieve a factor of 103 rejection of these events while remaining efficient for even the most difficult modes of proton decay (75% for p -> K +V ). It is predicted that radioactive triggers will occur at less than 3Hz when the full detector is operating. The neutrino induced background to proton decay has been simulated. The neutrino flux at the detector caused by cosmic ray induced showers in the atmosphere has been predicted. A comprehensive low energy (0.2 GeV to 20 GeV) Monte-Carlo neutrino event generator has been developed as a tool for background studies to proton decay. The Teinteraction of proton decay or neutrino interaction products in the parent nucleus is discussed. It is found that these reinteractions are quite probable, except for K⁺ and K° particles. Data from a low energy neutrino beam experiment has been studied and it is deduced that in some cases, the events seen in the detector will contain visible tracks associated with the disintegration of the parent nucleus. A background estimate for the mode p ➝ K+V from the neutrino interaction Vn ➝ μ~p is presented.
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Musser, Jordan M. H. "Development of a separation riser with flow pulsations for small coal particles." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4997.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains xiii, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 70-72).
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Skjöldebrand, Charlotte. "Model test for fabrication and separation of wear particles in hip implants." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-202060.
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Total hip replacement is a common orthopedic surgery today with a population with an increasing life expectancy and a more active lifestyle. Most implants have a life expectancy of 10 years or longer, however after 25 years one out of four implants has been revised. This means that the risk of a secondary surgery is high for young patients. In many cases the reason for revision is the formation of nanometer to micrometer sized particles that activate the immune system to resorb bone. The implants today usually consist of a femoral head of a cobalt chromium alloy and a cup of polyethylene. Replacing these materials with a cobalt chromium alloy with a silicon nitride coating is hoped to generate less and smaller wear particles that will not activate the immune system to resorb bone. This study compares wear particles from three different silicon nitride coatings with wear particles from polyethylene and a cobalt chromium alloy. The first was a standard coating, the second had a layered structure and the third had a nitrogen content gradient. This study uses a reciprocating motion with an alumina ball that slides against a sample of cobalt chromium with a silicon nitride coating in a serum solution to generate wear particles. The particles are then analyzed with a scanning electron microscope. In order to separate the particles from the serum solution two different methods were used. The first one used hydrochloric acid and the second used the enzyme proteinase K. Apart from the particles the wear tracks were investigated with vertical scanning interferometry and the adhesion was studied with scratch tests and light microscopy. The results show that the wear particles do not differ between the coatings. All coatings show a high wear volume, which is believed to be a consequence of the material combination, movement pattern or surface roughness of the counter surface. In conclusion the test set up generates particles of a relevant size and both methods for serum digestion were successful.
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Nguyen, Minh Chau. "Hydrodynamic transport phenomena in suspension of microalgae : particle separation using pulsatile flow." Thesis, Université Paris Cité, 2021. http://www.theses.fr/2021UNIP7174.
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La séparation des particules est nécessaire dans de nombreuses applications en chimie, physique, biologie, domaines médicaux et biotechnologie. Par exemple, la récolte de biomasse, qui est l'une des étapes clés de la production de biocarburants à partir des microalgues et des cyanobactéries, est un processus complexe et coûteux (20-30 % du coût total) en raison de la petite taille et aussi de la faible différence entre la densité des micro-organismes et celle de leurs milieux de culture. Ainsi, de nouvelles techniques peu coûteuses sont nécessaires pour remplacer ou améliorer le processus de la séparation. Tandis que plusieurs méthodes passives et actives ont été proposées pour la séparation des particules en écoulement stationnaire, l'écoulement pulsé a reçu moins d'attention. Le but de cette étude est de déterminer les effets de la pulsation d'écoulement sur la séparation des particules dans un microcanal du type « double Y». Seulement l'un des deux écoulements entrants contient des particules et l'efficacité de la séparation est définie comme le rapport entre le nombre des particules s'échappant de la sortie opposée et le nombre total des particules. Les cellules mortes et motiles de Chlamydomonas reinhardtii sont respectivement utilisées comme particules passives et actives. Des expériences microfluidiques et des simulations sont réalisées pour chaque partie de l'étude et les principaux résultats sont résumés ci-dessous: Pour les particules passives: - Lorsque les écoulements entrants dans le microcanal sont stationnaires, le seul paramètre qui permet de contrôler la séparation des particules est le rapport entre les débits aux entrées. L'efficacité de la séparation augmente avec l'augmentation de ce rapport. Pour approcher l'efficacité maximale (0,5), ce rapport doit être supérieur à 20, ce qui n'est pas toujours pratique. - Lorsque les écoulements entrants sont pulsés avec un déphasage, le réglage de ce déphasage peut contrôler l'efficacité de la séparation. - Lorsque 0,5 < amplitude de pulsation < 2 et 1 s < période de pulsation < 10 s, l'efficacité de la séparation augmente avec le déphasage de sorte qu'un déphasage de 180° aboutit à une efficacité maximale. Une tendance similaire est observée pour des valeurs plus élevées de l'amplitude (comme beta = 5) uniquement si la période de pulsation est suffisamment petite. Pour les particules actives: - Les particules actives (cellules motile) n'obéissent pas au protocole de contrôle imposé par la pulsation à l'entrée du système. Comme les particules actives choisissent aléatoirement leur sortie du microcanal, l'efficacité de la séparation reste toujours proche de 0,5. Par conséquent, la pulsation de l'écoulement (seule) ne présente aucun avantage par rapport à un écoulement stationnaire pour la séparation des particules actives. - Cependant, lorsque le comportement phototactique des algues est activé, l'avantage de la pulsation devient évident. En présence d'une stimulation lumineuse, l'efficacité de la séparation augmente respectivement jusqu'à 65 % et 75 % dans les écoulements stationnaires et pulsés. Bien que nos expériences soient menées sur une algue modèle (Chlamydomonas reinhardtii), une simulation numérique a démontré que l'idée d'utiliser un écoulement pulsé peut être étendue à la séparation de toutes autres particules actives stimulées par un champ externe attractif ou répulsif. Ainsi, les applications potentielles peuvent aller au-delà de la récolte des algues pour le control et l'amélioration des processus de séparation, de sélection ou d'accumulation sans avoir besoin de composants mécaniques ou de substances chimiquesParticle separation is an important requirement in chemistry, physics, biology, medical domains and biotechnology. For instance, the conventional biomass harvesting which is one of the key steps in production of biofuels from non-feed stocks such as microalgae and cyanobacteria, is a complex and costly process (20-30% of total cost) due to the small size and low-density difference of the photosynthesis microorganisms and their growth media. Thus, novel low-cost techniques are required to substitute or improve the downstream separation process. While a variety of active and passive techniques have been proposed for the separation process in steady flows, pulsatile flow has received much less attention. The purpose of this study is to determine the effects of flow pulsation on the separation of particles in a double Y-microchannel. Only one of the two entering flows contains the particles and the separation efficiency is defined as the ratio of the particles escaping from the opposite outlet to the total number of particles. Dead and motile cells of Chlamydomonas reinhardtii are used as passive and active particles, respectively. Both experiments and simulations are carried out for each part of the study. The key results can be summarized as follows: For passive particles: - When the inlet flows are in a steady regime, the only parameter that allows controlling the particle separation/distribution is the ratio between the flow rates at the inlets. The separation efficiency increases with increasing this ratio. To approach the maximum efficiency (0.5), this ratio should be more than 20, which is not always practical. - When the inlet flows are pulsating with a phase shift, adjusting the phase shift between the inlet flows can control the separation efficiency. - When 0.5 < pulsation amplitude < 2 and 1 s < pulsation period < 10 s, the separation efficiency increases with the phase shift such that phi = 180° gives the highest efficiency. A similar trend can be observed for higher values of amplitude (like beta = 5) only if the pulsation period is small enough. For active particles: - Active particles (motile cells) do not obey the control protocol imposed at the inlet of the system. The separation efficiency remains around 0.5 implying that active particles choose their exit from the microchannel randomly. Therefore, pulsation (alone) shows no advantage for separation of the active particles compared to a steady flow. - However, when the phototactic behavior of the algae is coupled with pulsatile flow features, the advantage of pulsation becomes clear. In the presence of light stimulation, the separation efficiency increases to 65% and 75% in steady and pulsatile flows respectively. Although the experiments are conducted on the well-known model alga, Chlamydomonas reinhardtii, a simplified numerical simulation demonstrated that the idea can be extended to any other active particle stimulated by an attractive or repulsive external field. Thus, the potential applications of pulsatile flow can go beyond algae harvesting to control and improve separation, selection or accumulation processes without using any mechanical component or chemical substance
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Regester, Jeremy L. "Separation of small particles due to density differences in a CFB riser system." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3377.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains xv, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 85-86).
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Rezaei, Nejad Hojatollah. "Development of techniques for rapid isolation and separation of particles in digital microfluidics." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57956.
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Digital microfluidics (DMF) has emerged as a powerful platform for both research and development in life science studies. The platform functions based on handling small volumes of samples and reagents in the form of discrete droplets using the well-established electrowetting on dielectric (EWOD) method. Based on EWOD, different techniques (operators) have been developed to accurately manipulate, dispense, split and merge droplets of different volumes. Despite the advances made in the DMF technology especially in the use of EWOD in scaling down laboratory procedures, there is lack of understanding and hence development of techniques for particle/cell manipulation and isolation on DMF (as compared to the alternative platform called continuous microfluidics). This has hindered the capability of DMF in full-scale miniaturization of laboratory procedures requiring particle/cell isolation at any of their steps. This research focuses on addressing this problem and developing reliable techniques to manipulate, concentrate and isolate different types of particles/cells. The techniques presented here are particularly developed to limit the use of external devices and also cover a wide range of particles and cells with different physical properties (including size, density, material and electromagnetic properties). They include magnetic collection, hydrodynamic focusing, dielectrophoresis positioning of the particles. The magnetic collection method, a rather simple but effective and widely used in biochemistry, is implemented on DMF for capturing target analytes. The hydrodynamic focusing method, functioning based on the density and size of the particles, were developed and integrated into DMF (for the first time) using especial electrode geometry facilitating the rotation of the droplet. The dielectrophoresis–based particle manipulation is optimized to achieve high resolution and controllability in particle patterning on DMF. The applicability of each of these techniques are demonstrated for different biological and physical applications including on-chip DNA purification (using the magnetic collection technique), ultra-low DNA concentration (using the hydrodynamic focusing technique for achieving desired concentrations of particles), and cell and particle patterning and cell culturing on a DMF platform (using the dielectrophoresis positioning technique). The diversity and flexibility of these techniques will enable the use of DMF devices for especially point-of-care applications.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
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Akhtar, Zatoun. "Separation of naphthenic acid from an oil phase using designed magnetic composite particles." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406272.
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Annavarapu, V. N. Ravikanth (Venkata Nagandra Ravikanth). "Size based separation of submicron nonmagnetic particles through magnetophoresis in structured obstacle arrays." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59872.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references.
The focus of this work was on developing a novel scalable size based separation technology for nonmagnetic particles in the submicron size range utilizing magnetophoretic forces. When a nonmagnetic particle is immersed in a magnetic fluid and subjected to magnetic field gradients, it behaves like a magnetic hole and experiences magnetic buoyancy forces proportional to its volume. This size dependence of magnetic buoyancy forces can be exploited to selectively focus larger nonmagnetic particles from a mixture and thus we can fractionate nonmagnetic particles on the basis of size. We designed a separation system composed of a regular array of iron obstacle posts which utilized magnetic buoyancy forces to perform size based separations. A Lagrangian particle tracking model was developed which could describe the behavior of a nonmagnetic particle in regions of inhomogeneous magnetic field gradients. Particle trajectories were simulated for a number of obstacle array geometries and over a range of operating conditions in order to understand the nature of the magnetic buoyancy force and aid in separation system design. Based on the results of the trajectory simulations, an experimental set up was conceptualized and built to demonstrate capture and separation of nonmagnetic particles using magnetic buoyancy forces. Capture visualization experiments were performed utilizing fluorescence microscopy which showed visual evidence of focusing and preferential capture of larger nonmagnetic particles. Experiments also yielded results qualitatively consistent with the Lagrangian trajectory model. Pulse chromatography experiments were also performed in order to quantitatively understand the capture and separation behavior. The results obtained showed quantitative evidence of preferential capture of larger particles. Particle capture efficiencies were compared with predictions from simulations and were found to be qualitatively consistent. Finally, the potential of this separation technology was demonstrated by performing proof-of-concept separation experiments with a mixture of 840 nm and 240 nm particles.
by V. N. Ravikanth Annavarapu.
Ph.D.
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Wang, Desheng. "CDSE Quantum Dots and Luminescent/Magnetic Particles for Biological Applications." ScholarWorks@UNO, 2005. http://scholarworks.uno.edu/td/142.
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CdSe semiconductor nanocrystals (quantum dots--QDs) with diameters ranging between 1.5 and 8 nm exhibit strong, tunable luminescence [1-5]. They have been widely investigated for their size-dependent optoelectronic properties [6], and for their potential use in optical devices [7], biological labels [8] and sensors [9]. Luminescent quantum dots (QDs) show higher photostability and narrower emission peaks compared to organic fluorophores [8]. The objective of my project was to apply QDs magnetic/luminescent nanoparticle as biological labels in cells. Luminescent CdSe QDs emit bright visible light with high quantum yield and sharp emission peak. The CdSe QDs were capped with a ZnS layer. This increased their emission efficiency and photostability due to the larger band gap of ZnS. The QDs were transferred from organic solvent (e.g. chloroform, hexane) to water by exchanging the capping group (Trioctylphosphine Oxide—TOPO) with mercaptoacetic acid. To develop a separation and detection tool for cells, we combined γ-Fe2O3 magnetic particles with CdSe/ZnS QDs in core-shell composite. The composite nanoparticles showed strong fluorescence emission and high water solubility. Different antibodies were attached to the particles through EDAC coupling. The antibody-coated particles were used to successfully separate and detect breast cancer cells in blood cells.
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Wang, Bo. "TOWARDS COMMERCIALIZABLE FEATURED ZEOLITES - MESOPOROUS PARTICLES, NANOPARTICLES AND BENDABLE ZEOLITE MEMBRANES." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1478609347266087.
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Del, Río De Vicente José Ignacio. "Cellulose nanocrystals functionalized cellulose acetate electrospun membranes for adsorption and separation of nanosized particles." Thesis, Luleå tekniska universitet, Materialvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-85516.
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Filtration and separation technologies remain as one of the biggest challenges humanity currently faces. The separation of different elements such as bacteria, viruses, heavy metals, particles, and chemical agents require the development of multifunctional membranes. In membrane technology, one of the most promising fabrication techniques is electrospinning, which can produce highly tailored non-woven fibrous multifunctional membranes with a high surface area. On the other hand, cellulose derivatives, like cellulose acetate, have many beneficial properties for filtering technology such as high availability and easy functionalization. Likewise, cellulose nanocrystals are used to improve mechanical properties and functionalize membranes. In this project, a cellulose nanocrystal (CNCs) functionalized cellulose acetate electrospun multifunctional membrane is developed for adsorption and separation of nanosized particles. In this work, cellulose acetate (CA) fibers with an average fiber diameter of approximately 900 nm were electrospun and tested as membranes for size and affinity based filtration. First, the electrospinning process was optimized regarding solution and process parameters. As a result, solution parameters were found to be 12 wt% solid content CA dissolved in a 1:1 acetone:acetic acid solution. Regarding process parameters, the suitable electrospinning parameters were found to be 18 kV applied voltage, a feeding rate of 5 mL/h, and a tip-to-collector distance of 20 cm. The electrospun CA membrane was coated with cationic (+) and anionic (-) cellulose nanocrystals up to a 25 wt% concentration. The incorporation of CNCs, of either anionic or cationic surface charge, affected membrane wettability. The neat CA membrane had a hydrophobic behavior with a contact angle of 110°. The addition of CNCs decrease contact angle, to 31.5° for CA-CNCs(-) and 50° for CA-CNCs(+), which resulted in functionalized membranes with a hydrophilic behavior. Both functionalized membranes managed to maintain high flux values. CA-CNCs(-) maintained a flux of 9500 Lm−2h−1, while CA-CNCs(+) maintained a flux of 6700 Lm−2h−1. The addition of cellulose nanocrystals improved the mechanical properties of the CA membranes. The tensile strength increases from 410 kPa to 4990 kPa for CA-CNCs(-) membranes and 3010 MPa for CA-CNCs(+) membranes, and is accompanied by an increase in Young’s modulus as well. To evaluate the adsorption efficiency and size-exclusion filtration, an anionic dye (Congo red), a cationic dye (Victoria blue), and 500 nm model particles were used. CA-CNC(-) membranes achieved a removal efficiency of 96% of 500 nm particles with an affinity-based dye removal of 63% of Victoria blue dye. On the other hand, CA-CNC(+) membranes achieved a removal efficiency of 43% of 500 nm particles with a dye removal of 27% of Congo red dye. In this regard, CA-CNC(-) membranes were the best candidate for size-exclusion filtration, while also maintaining a good level of adsorption. Cellulose based composite membranes were successfully produced as multifunctional filters that could act in both size-exclusion regime and affinity-based regime. A cellulose acetate fibrous membrane was produced by electrospinning, tuning for fiber size and porosity, while the incorporation of cellulose nanocrystals functionalizes the membranes and enhance mechanical properties, and wettability.
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Bock, Christopher Paul. "Particle separation through Taylor-Couette flow and dielectrophoretic trapping." Master's thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4625.
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As the world population approaches seven billion, a greater strain is put on the resources necessary to sustain life. One of the most basic and essential resources is water and while two thirds of the earth is covered by water, the majority is either salt water (oceans and seas) or it is too contaminated to drink. The purpose of this project is to develop a portable device capable of testing whether a specific source of water (i.e. lake, river, well ...) is potable. There are numerous filtration techniques that can remove contaminants and make even the dirtiest water clean enough for consumption but they are for the most part, very time consuming and immobile processes. The device is not a means of water purification but rather focuses on determining the content of the water and whether it is safe. Particles within the water are separated and trapped using a combination of a Taylor Couette fluid flow system and Dielectrophoretic electrodes. This paper explores Taylor Couette flow in a large gap and low aspect ratio system through theory and experimentation with early stage prototypes. Different inner cylinder radii, 2.12cm, 1.665cm and 1.075cm, were tested at different speeds approaching, at and passing the critical Taylor number, 3825, 4713 and 6923 respectively for each cylinder. Dielectrophoretic (DEP) electrodes were designed, fabricated, coated and tested using latex beads to determine the method of integrating them within the fluid flow system. Taylor Couette theory, in terms of the formation of vortices within the large gap, small aspect ratio system, was not validated during testing. The flow pattern generated was more akin to a chaotic circular Couette flow but still served to move the particles toward the outer wall. Fully integrated tests were run with limited success.; Recommendations were made to pursue both circular Couette flow as the basis for particle separation and dimensional changes in the setup to allow for the formation of Taylor vortices by increasing the radius ratio but still allowing for a larger volume of fluid.ID: 028916599; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2010.; Includes bibliographical references (p. 108-109).
M.S.M.E.
Masters
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Miniature Engineering Systems
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MORADI, KAMRAN. "Acoustic Manipulation and Alignment of Particles for Applications in Separation, Micro-Templating, and Device Fabrication." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/1753.
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This dissertation studies the manipulation of particles using acoustic stimulation for applications in microfluidics and templating of devices. The term particle is used here to denote any solid, liquid or gaseous material that has properties, which are distinct from the fluid in which it is suspended. Manipulation means to take over the movements of the particles and to position them in specified locations.
Using devices, microfabricated out of silicon, the behavior of particles under the acoustic stimulation was studied with the main purpose of aligning the particles at either low-pressure zones, known as the nodes or high-pressure zones, known as anti-nodes. By aligning particles at the nodes in a flow system, these particles can be focused at the center or walls of a microchannel in order to ultimately separate them. These separations are of high scientific importance, especially in the biomedical domain, since acoustopheresis provides a unique approach to separate based on density and compressibility, unparalleled by other techniques. The study of controlling and aligning the particles in various geometries and configurations was successfully achieved by controlling the acoustic waves.
Apart from their use in flow systems, a stationary suspended-particle device was developed to provide controllable light transmittance based on acoustic stimuli. Using a glass compartment and a carbon-particle suspension in an organic solvent, the device responded to acoustic stimulation by aligning the particles. The alignment of light-absorbing carbon particles afforded an increase in visible light transmittance as high as 84.5%, and it was controlled by adjusting the frequency and amplitude of the acoustic wave. The device also demonstrated alignment memory rendering it energy-efficient. A similar device for suspended-particles in a monomer enabled the development of electrically conductive films. These films were based on networks of conductive particles. Elastomers doped with conductive metal particles were rendered surface conductive at particle loadings as low as 1% by weight using acoustic focusing. The resulting films were flexible and had transparencies exceeding 80% in the visible spectrum (400-800 nm) These films had electrical bulk conductivities exceeding 50 S/cm.
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Phanapavudhikul, Ponpan. "Design and performance of magnetic composite particles for the separation of heavy metals from water." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408066.
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Shendruk, Tyler. "Theoretical and Computational Studies of Hydrodynamics-based Separation of Particles and Polymers in Microfluidic Channels." Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/30423.
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The advent of microfluidic technology presents many difficulties but also many opportunities for separation science. Leveraging the potential of micro- and nanofluidic geometries is not only a matter of shrinking systems. Miniaturization can shift the relative importance of physical phenomena leading to separation. Theoretical and computational studies into the consequences of miniaturization are vital. Mesoscopic, multi-particle collision dynamics simulations are performed on polyelectrolytes and hard, colloidal solutes. Multiple variations of this simulation algorithm are implemented to achieve versatility for simulating non-equilibrium flows and dispersed solutes. The algorithm is extended to simulate the effects of finite Debye layers on the electro-hydrodynamics of electrophoresing macromolecules and used to study the electrophoresis of charged oligomers, polyelectrolytes and polyampholytes in both free-solution and confined geometries. Multi-particle collision dynamics simulations of hydrodynamic chromatography and field-flow fractionation are also performed to test the predictions of the derived unified, ideal retention theory. This unified, ideal retention predicts the transitions between multiple operational modes, including Faxén-mode FFF. Simulations and the theory show that increases in drag due to hydrodynamic interactions with microfluidic channel walls perturb the retention curves from the ideal predictions at large particle sizes. Further complications to field-flow fractionation including undesirable forces perpendicular to the flow direction, slip at channel walls and rectangular channel geometries are investigated. These theoretical studies lead to the proposal of several novel fractionation techniques, namely adverse-mode FFF, slip-mode FFF and polymer/depletant HC.
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Phisarnchananan, Nataricha. "The effect of particles on the phase separation of waxy corn starch plus galactomannan gums." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/13115/.
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This thesis was initiated with the aim of studying the effect of small particles on phase separation of polysaccharide mixtures with the expectation of stabilising the mixture for a longer period of time, completely inhibiting phase separation, or changing the phase-separated microstructure. The phase separation of a model system consisting 2 wt.% waxy corn starch + 0.25 wt.% guar gum or 0.3 wt.% locust bean gum was studied at 25 °C at pH 7. Phase separated networks occurred within 30 minutes after preparation where the upper phase was enriched with galactomannan gum whereas the lower phase contained starch. Macroscopic phase separation of mixed polysaccharides was studied at vary concentrations, i.e., 0.5 – 4 wt.% and 0.05 – 0.6 wt.% galactomannan gums. The phase diagram illustrating the binodal lines almost coincided with the axes representing the polysaccharide concentrations. Microscopic results showed that the morphology of both mixtures exhibited thermodynamic incompatibility via spinodal decomposition structure. The model systems were also studied in the presence of different kinds of particles. There are three main types of particles that were selected in this thesis; silica nanoparticles (at different hydrophobicities), oil-in-water stable microdroplets and whey protein microgel particles with an initial particle size of 20 nm, 280 nm and 149 nm, respectively. The key parameters investigated were particle concentration, size and effect of pH. This particle-stablised model W/W emulsion was shown to induce long-term stability. With silica particles, the results showed that the rate of phase separation was inversely proportional to particle concentration. The observation also showed that the phase separation of polysaccharide mixtures was significantly slowed down in the presence of 0.5 wt.% of the 80-SiOH and 65-SiOH particles and fully inhibited at 1 wt.% particle concentration. The microdroplets appeared to slow down the rate of phase separation but within one month of storage all mixtures showed the sign of phase separation. The phase separation of a model system, starch + locust bean gum, was significantly inhibited in the presence of 1 vol.% whey protein microgel particles at pH 4, whilst the microgel particles were not as effective in starch + guar gum systems.
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Hanazawa, Tomohito. "Effects of fat particles on the stability of complex food systems." Kyoto University, 2019. http://hdl.handle.net/2433/242551.
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Johnson, Lynn. "Jet properties in deep inelastic scattering and the separation of quark and gluon jets using a neural network technique." Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240404.
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Olanrewaju, Kayode Olaseni. "The rheology and phase separation kinetics of mixed-matrix membrane dopes." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39466.
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Mixed-matrix hollow fiber membranes are being developed to offer more efficient gas separations applications than what the current technologies allow. Mixed-matrix membranes (MMMs) are membranes in which molecular sieves incorporated in a polymer matrix do separation between gas mixtures based on the molecular size difference and/or adsorption properties of the component gases vis-à-vis the porous structure and the nature of adsorption sites in the molecular sieve. The development of MMMs to deliver on its promises has however been slow. The major challenges encountered in the efficient development of MMMs are associated with some of the paradigm shifts involved in their processing. For instance, mixed-matrix hollow fiber membranes are prepared by a dry-wet jet spinning method. For an efficient large scale processing of hollow fibers the rheology and kinetics of phase separation of the MMM dopes are important control variables in the process design. Therefore, this research thesis aims to study the rheology and phase separation kinetics of mixed-matrix membrane dopes.
In research efforts to develop predictive models for the shear rheology of suspensions of zeolite particles in polymer solutions it was found that MFI zeolite suspensions have relative viscosities that dramatically exceed the Krieger-Dougherty predictions for hard sphere suspensions. Our investigations show that the major origin of this discrepancy is the selective absorption of solvent molecules from the suspending polymer solution into the zeolite pores. Consequently, both the viscosity of the polymer solution and the particle contribution to the suspension viscosity are greatly increased. A predictive model for the viscosity of porous zeolite suspensions incorporating a solvent absorption parameter, α, into the Krieger-Dougherty model was developed. We experimentally determined the solvent absorption parameter and our results are in good agreement with the theoretical pore volume of MFI particles. In addition, fundamental studies were conducted with spherical nonporous silica suspensions to elucidate the role of colloidal and hydrodynamic forces on the rheology of mixed-matrix membrane dopes.
Also in this thesis, details of a novel microfluidic device that enables measurements of the phase separation kinetics via video-microscopy are presented. Our device provides a well-defined sample geometry and controlled atmosphere for in situ tracking of the phase separation process. We have used this technique to quantify the phase separation kinetics (PSK) of polymer solutions and MMM dopes upon contact with an array of relevant nonsolvent. For the polymer solution, we found that PSK is governed by the micro-rheological and thermodynamic properties of the polymer solution and nonsolvent. For the MMM dopes, we found that the PSK is increased by increased particles surface area as a result of surface diffusion enhancement. In addition, it was found that the dispersed particles alter the thermodynamic quality of the dope based on the hydrophilic and porous nature of suspended particles.
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Kirsch, Hans. "Entwicklung eines Verfahrens zur material- und struktursensitiven Trennung gasgetragener Partikel - Material and structure dependent separation of aerosol particles." Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-05292001-122009/.
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The interest in nano particles from the view of basic and applied research has constantly risen in recent years. Since their physical properties are different from those of bulk materials, new industrial applications are emerging, e.g. in microelectronics. For quality control, particle production technologies call for on-line techniques that respond to the chemical nature of the particles. A particle generation process usually leads to particles with different surface properties. These surface properties, i.e. impurities ( like an oxygen layer ) or the crystal habit of single particles, determines much of their behaviour, especially in the diameter range of a few nanometers. While this fact has hardly been recognized, we anticipate that new technologies will establish a demand not only for analysis but also for separation of chemically pure particles with respect to their surface properties. In these PHD thesis we introduce a method and a device to separate aerosol particles according to their photoelectric properties. These strongly depend on particle surface composition as well as the particle morphology.
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Gorkowski, Kyle J. "The Morphology and Equilibration of Levitated Secondary Organic Particles Under Controlled Conditions." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1067.
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I advanced the understanding of particle morphology and its implications for the behavior and effects of atmospheric aerosol particles. I have developed new experimental methods for the Aerosol Optical Tweezers (AOT) system and expanded the AOT’s application into studying realistic secondary organic aerosol (SOA) particle phases. The AOT is a highly accurate system developed to study individual particles in real-time for prolonged periods of time. While previous AOT studies have focused on binary or ternary chemical systems, I have investigated complex SOA, and how they interact with other chemical phases, and the surrounding gas-phase. This work has led to new insights into liquid-liquid phase separation and the resulting particle morphology, the surface tension, solubility, and volatility of SOA, and diffusion coefficients of SOA phases. I designed a new aerosol optical tweezers chamber for delivering a uniformly mixed aerosol flow to the trapped droplet’s position. I used this chamber to determine the phase-separation morphology and resulting properties of complex mixed droplets. A series of experiments using simple compounds are presented to establish my ability to use the cavity enhanced Raman spectra to distinguish between homogenous single-phase, and phase-separated core-shell or partially-engulfed morphologies. I have developed a new algorithm for the analysis of whispering gallery modes (WGMs) present in the cavity enhanced Raman spectra retrieved from droplets trapped in the AOT. My algorithm improves the computational scaling when analyzing core-shell droplets (i.e. phase-separated or biphasic droplets) in the AOT, making it computationally practical to analyze spectra collected over many hours at a few Hz. I then demonstrate for the first time the capture and analysis of SOA on a droplet suspended in an AOT. I examined three initial chemical systems of aqueous NaCl, aqueous glycerol, and squalane at ~ 75% relative humidity. For each system I added α-pinene SOA – generated directly in the AOT chamber – to the trapped droplet. The resulting morphology was always observed to be a core of the initial droplet surrounded by a shell of the added SOA. By combining my AOT observations of particle morphology with results from SOA smog chamber experiments, I conclude that the α-pinene SOA shell creates no major diffusion limitations for water, glycerol, and squalane under humid conditions. My AOT experiments highlight the prominence of phase-separated core-shell morphologies for secondary organic aerosols interacting with a range of other chemical phases. The unique analytical capabilities of the aerosol optical tweezers provide a new approach for advancing the understanding of the chemical and physical evolution of complex atmospheric particulate matter, and the important environmental impacts of aerosols on atmospheric chemistry, air quality, human health, and climate change.
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Lohe, Martin R., Kristina Gedrich, Thomas Freudenberg, Emanuel Kockrick, Til Dellmann, and Stefan Kaskel. "Heating and separation using nanomagnet-functionalized metal–organic frameworks." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138610.
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A magnetic functionalization of microcrystalline MOF particles was realized using magnetic iron oxide particles. Such magnetic MOFs can be separated using a static magnetic field after use in catalytic processes and heated by an external alternating magnetic field to trigger desorption of encaged drug moleculesDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Gao, Changhong. "A network model for capture of suspended particles and droplets in porous media." Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/981.
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Produced water presents economical and environmental challenges to oil producers. Downhole separation technology is able to separate oil or gas from produced fluid in downhole environment and injects waste water into deeper formations, thus saving energy and reducing waste emission. More than 120 downhole separation systems have been installed worldwide, but only about 60% of the installations achieved success. Most of the failures were due to the injectivity decline under the invasion of impurities in the injected water, such as suspended particles and oil droplets. A reliable model is needed to predict the reaction of reservoir permeability under the invasion of such impurities and serves as a tool to screen appropriate formations for downhole separator installations.Previous experimental studies on particle-induced permeability damage reveal that high particle concentration, low fluid velocity, large particle size lead to more severe damage. The damage mechanisms are attributed to surface interception, bridging and size exclusion of particles in porous media. While for droplets, the resultant permeability decline is mostly due to surface interception. Empirical correlations with key parameters determined by core flooding data are widely applied to the simulation of permeability decline under invasion of particles and droplets. These correlations are developed based on characteristics of certain rocks and fluids, thus their applications are very restricted.A more scientific method is to model the flow and capture of particulates at pore level. Reservoir rocks are porous media composed of pores of various sizes. Pore network models employ certain assumptions to imitate real porous media, and have been proved realistic in simulating fluid flow in porous media. In this study, a 2-dimensional square network model is used to simulate capture of particles and droplets in porous media. Pore bodies are represented by globes and pore throats are imitated with capillary tubes. The flow rates in the network are obtained by simultaneously solving mass balance equations at each pore body. The network model is tuned to match the porosity and permeability of a certain rock and serves as the infrastructure where the capture process takes place.Particles are categorized as Brownian and non-Brownian particles according to size. For Brownian particles, diffusion is dominant and Fick’s law is applied to each pore inside the network to obtain deposition rate. For non-Brownian particles, their trajectories are mainly governed by gravity and drag force acting on them. Besides, the size of each particle is compared with the size of the pore where it is captured to determine the damage mechanism. For particles much smaller than the pore size, surface deposition is dominant and the permeability decline is gradual. For particles with sizes comparable to pore size, bridging and clogging are dominant and the permeability decline is much more severe.Unlike particles, droplets can not be captured on top of each other. Accordingly, a captureequilibrium theory is proposed. Once the pore surface is covered by droplets, equilibrium is reached and droplets flow freely through porous media without being captured. The simulation on capture of oil droplets reveals that the surface wettability has significant influence on the resultant permeability damage. Most natural reservoirs are neutrally or oil wet. It is thus recommended to apply these surface conditions to future simulations.The proposed model is validated with test data and reasonably good agreements are obtained. This new mechanistic model provides more insights into the capture process and greatly reduces the dependence on core flooding data.