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Lin, Han. "GRAPHENE OXIDE-BASED MEMBRANE FOR LIQUID AND GAS SEPARATION." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1595260029225206.
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Borkar, Neha. "Characterization of microporous membrane filters using scattering techniques." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289943937.
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Lloyd, Michael C. "Novel materials for membrane separation processes." Thesis, Aston University, 1995. http://publications.aston.ac.uk/9680/.
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The aim of this work was to synthesise a series of hydrophilic derivatives of cis-1,2-dihydroxy-3,5-cyclohexadiene (cis-DHCD) and copolymerise them with 2-hydroxyethyl methacrylate (HEMA), to produce a completely new range of hydrogel materials. It is theorised that hydrogels incorporating such derivatives of cis-DHCD will exhibit good strength and elasticity in addition to good water binding ability. The synthesis of derivatives was attempted by both enzymatic and chemical methods. Enzyme synthesis involved the transesterification of cis-DHCD with a number of trichloro and trifluoroethyl esters using the enzyme lipase porcine pancreas to catalyse the reaction in organic solvent. Cyclohexanol was used in initial studies to assess the viability of enzyme catalysed reactions. Chemical synthesis involved the epoxidation of a number of unsaturated carboxylic acids and the subsequent reaction of these epoxy acids with cis-DHCD in DCC/DMAP catalysed esterifications. The silylation of cis-DHCD using TBDCS and BSA was also studied. The rate of aromatisation of cis-DHCD at room temperature was studied in order to assess its stability and 1H NMR studies were also undertaken to determine the conformations adopted by derivatives of cis-DHCD. The copolymerisation of diepoxybutanoate, diepoxyundecanoate, dibutenoate and silyl protected derivatives of cis-DHCD with HEMA, to produce a new group of hydrogels was investigated. The EWC and mechanical properties of these hydrogels were measured and DSC was used to determine the amount of freezing and non-freezing water in the membranes. The effect on EWC of opening the epoxide rings of the comonomers was also investigated
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Herigstad, Matthew Omon. "Hybrid Particle-Nonwoven Membrane Materials for Bioseparations." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-04042009-120426/.
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Adsorption separations performed in feed streams containing large particulates pose interesting problems, the solution of which would aid in many fields of bioseapartions. Production of biologically derived protein products is one of the most rapidly expanding sectors in the global economy. The capture and purification of these products has, of late, become the bottleneck of the industry and can account for approximately 50-80% of the production costs. The biopharmaceutical industry has begun to focus on improving overall economics by merging two or more separation schemes into one. The majority of the emphasis has been on combining the initial protein capture and host cell clearance steps; however, many of the currently available methods have shown little efficacy at large-scale. Additionally, interest in the clearance of pathogenic activity, most importantly infectious prions, from blood and blood derived products has grown over the past decade with the increased threat of blood-transfusion of variant Creutzfeldt-Jakob disease. This work characterizes the transport and binding properties of a novel hybrid particle-nonwoven membrane medium in which a polymeric chromatographic resin is entrapped between layers of a nonwoven polypropylene membrane (a particle-impregnated membrane or PIM). This membrane-supported resin construct offers the advantage of increased interstitial pore diameter to allow passage of cells and other debris in the feed, while providing sufficiently high surface area for product capture within the resin particles. Columns packed with stacked disks of PIM displayed excellent flow distribution, and had an interstitial porosity of εb = 0.48 ± 0.01, a 25-60% increase over those typically observed in a packed bed. These columns were able to pass over 95% of E. coli cells and human red blood cell concentrate (RBCC) in 30 column volumes, while maintaining a pressure drop significantly lower than that of a packed bed. The dynamic binding capacity of the chromatographic resin entrapped in the PIM packed column for bovine serum albumin (BSA) was essentially the same as that observed with the same volume of resin in a packed bed. Additionally, the binding of prion was characterized to PIM constructs containing an affinity ligand for PrPSc, in saline, RBCC, and human IgG solutions. The General Rate (GR) model of chromatography was used to analyze experiments indicating that the breakthrough and elution behaviors of the PIM column are predictable, and very similar to those of a normal packed bed. These results indicate that PIM constructs can be designed to process viscous mobile phases containing particulates while retaining the desirable binding characteristics of the embedded chromatographic resin. The PIM systems could find uses in adsorption separation processes from complex feed streams such as whole blood, cell culture, and food processing and could offer a process alternative to expanded beds.
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Boukili, Aishah. "Synthesis and characterisation of sulphonated polyethersulphone membrane materials." University of Western Cape, 2020. http://hdl.handle.net/11394/7337.
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>Magister Scientiae - MScWith current climate change, growing population, and rapid industrialization of developing countries, water is increasingly becoming a scare resource. Within a power plant, processes that consume most water are demineralized water production (boiler make-up), heat rejection (cooling) and emission control (wet flue gas desulfurization). Eskom’s fleet of existing coal-fired power plants are not equipped with SO2 abatement technologies and therefore retrofitting of the plants will be required to meet the compliance levels for SO2 emissions.
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Giorgini, Federica. "Caratterizzazione dei materiali per membrane di dialisi attraverso lo studio dei meccanismi di trasporto." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17904/.
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L’insufficienza renale è una condizione che colpisce milioni di persone al mondo. Gli individui affetti da patologie renali sono purtroppo soggetti ad un progressivo ed inesorabile peggioramento della qualità della vita. Al giorno d’oggi è possibile garantire una vita normale ai pazienti, grazie a un procedimento chiamato dialisi. Esistono diverse tecniche dialitiche ma tutte si propongono lo stesso obiettivo: sostituire la funzione renale nei soggetti in cui questa sia irrimediabilmente compromessa. Le tecniche dialitiche si sono evolute nel corso degli anni e tra le innovazioni di maggior importanza si evidenzia l’impiego di nuovi materiali per la realizzazione della membrana di dialisi. In questo studio di tesi si è analizzato lo stato dell’arte dei materiali impiegati per la produzione di membrane attualmente in uso su macchine di dialisi, studiando i fenomeni di trasporto della materia attraverso una membrana semipermeabile e i parametri che la caratterizzano. In particolare si è rivolta l’attenzione a come questi materiali possano garantire una maggior efficienza nella rimozione delle tossine e nella riduzione della mortalità associata al contatto della membrana con il sangue, permettendo di migliorare la qualità della terapia dialitica mediante la possibilità di realizzare fibre con diverse caratteristiche ottenute agendo sui parametri fondamentali delle membrane come cut off, coefficienti di ultrafiltrazione e di sieving e a loro volta questi parametri uniti alla possibilità di disporre le fibre all’interno dei filtri secondo diverse geometrie, in base alle esigenze, permettono di adattare la terapia di dialisi alle necessità di ciascun paziente.
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Zhou, Yi. "Membrane-Based Gas Separation For Carbon Capture." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595254659184073.
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Tam, Chung Ming. "Use of liquid chromatography in membrane material characterization." Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5701.
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Vieira, Delia do Carmo. "Fabricação de elementos vítreos porosos para o depósito de biopolímeros visando a obtenção de membranas com superfícies ativas." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-18062002-142324/.
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Este trabalho tem como foco dois aspectos principais: i) O processamento e caracterização de elementos porosos vítreos, a partir de vidro reciclado e ii) A deposição de filmes de quitosana (CHI) e carboximetilcelulose (CMC). O objetivo é a avaliação da interação superficial desses filmes com o herbicida atrazina (ATZ) em meio aquoso. O processamento seguiu o princípio do preenchimento (filler principle), fazendo uso dos sais NaCl e o MgCO3 como fases formadoras de poros. A caracterização mostra que o NaCl, age como um elemento solúvel, inerte, exceto na interface NaCl-matriz vítrea, cuja estrutura cristalina final é a cristobalita. Contrariamente, o MgCO3 reage com a matriz introduzindo novas fases como o CaMg(SiO3)2. A estrutura final, de poros e da matriz, é distinta para cada um dos sais utilizados, principalmente quanto ao aspecto morfológico dos poros e as análises semiquantitativas mostraram que o cátion Na+ na interface vidro-NaCl e o íon Mg++ atuam como modificadores de cadeia. Medidas de porosimetria indicam que nos materiais processados com NaCl apresentam estruturas dos poros abertos com uniformidade na distribuição dos tamanhos e com certa regularidade de formatos quando comparados com os materiais processados com MgCO3. Com respeito à interação herbicida - materiais vítreos, esta foi avaliada por técnicas espectroscópicas, podendo-se inferir que há interação entre as superfícies ativadas quimicamente e a ATZ. A remoção do herbicida por filtragem simples através dos filmes de CHI e filmes de CHI+CMC depositados sobre as membranas foram inferiores numericamente aos valores obtidos pela ação da superfície vítrea ausente de filmes. Entretanto, os resultados indicam que ocorre uma melhor interação entre a CHI e o ATZ, quando ambos estão em solução a pH = 3,0. Por espectroscopia de fotoelétrons excitada por raios-X (XPS) houve o aumento das espécies O (1s), C (1s), N (1s) e Cl (2s) confirmando as interações com o herbicida, porém não sendo possível inferir se esta se dá por algum grupo proveniente da CHI ou por sítios livres disponíveis na superfície vítrea. Análises numéricas indicam remoções de ATZ na ordem de 10-12% com respeito às medidas realizadas em sistemas contendo uma única membrana. Avaliação complementar da remoção do metal (Cd) confirmam a vantagem das superfícies depositadas com CHI, para este tipo de interação, indicando que sistemas compostos podem ser vantajosos na remoção de diversos contaminantes.This work is focused in two main aspects: i) The processing and characterization of porous vitreous pieces, produced from waste glass and ii) The deposition of chitosan (CHI) and carboximethilcelullose (CMC) on the vitreous surface. The evaluation of the active aspects aiming at interactions with the herbicide atrazine (ATZ) was realized in aqueous medium. The processing follows the filler principle making use of NaCl and MgCO3 as porous phases formation. Characterization showed that NaCl acts as a soluble, inert phase, with interaction over NaCl-Matrix interface, resulting in cristobalite phase as final structure. Conversely, the MgCO3 reacts along the matrix generating new phases such as CaMg(SiO3)2. The final porous and matrix structure also differs to each used salt, mainly concerning morphological aspects of the porous where semiquantitive analysis point to the Na+ in glass-NaCl interface and to Mg++ as the main chain modifiers. Measurements by porosimetry has showed that in the materials processed with NaCl the porous structure are typically open with uniform size distribution and present a certain regularity of forms when compared with the membranes processed with MgCO3. Concerning an herbicide interaction, which was evaluated by spectroscopic techniques inferring interaction between chemically active surfaces and ATZ. The herbicide removal through CHI and CHI+CMC deposited films resulted numerically lower than those values attained to glass surface absent of films. Nevertheless, the results point that to a better interaction between CHI and ATZ when both are dissolved at pH 3,0. By XPS scanning it was possible to follow the variation of the surface concentration with increasing of the elements O (1s), C (1s), N (1s) e Cl (2s) confirming surface interaction, despite not being feasible to define what functional groups take place in the interaction. Numerical analysis presents herbicide removal in the order of 10-12% concerning measure performed over a single membrane. Complementary tests of metal removal (Cd) confirmed the advantage of CHI surface in this type of interaction, making evident that composed filtration system could be ideal in the removal of distinct contaminants.
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Achoundong, Carine Saha Kuete. "Engineering economical membrane materials for aggressive sour gas separations." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50289.
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The goal is of this project was to identify principles to guide the development of high performance dense film membranes for natural gas sweetening using hydrogen sulfide and carbon dioxide gas mixtures as models under aggressive sour gas feed conditions. To achieve this goal, three objectives were developed to guide this research.
The first objective was to study the performance of cellulose acetate (CA) and an advanced crosslinkable polyimide (PDMC) dense film membrane for H₂S separation from natural gas.
The second objective was to engineer those polymers to produce membrane materials with superior performance as measured by efficiency, productivity, and plasticization resistance, and the third objective was to determine the separation performance of these engineered membrane materials under more aggressive, realistic natural gas feeds, and to perform a detailed transport analysis of the factors that impact their performance.
Work on the first objective showed that in neat CA, penetrant transport is controlled by both the solubility and mobility selectivity, with the former being more dominant, leading to a high overall CO₂/CH₄ (33) and H₂S/CH₄ (35) ideal selectivities. However, in uncrosslinked PDMC, H₂S/CH₄ selectivity favored sorption only, whereas CO₂/CH₄ selectivity favored both mobility and sorption selectivity, leading to a high CO₂/CH₄ (37) but low H₂S/CH₄ (12) ideal selectivities. However, the latter polymer showed more plasticization resistance for CO₂.
In the second objective, both materials were engineered. A new technique referred to as “GCV-Modification” was introduced in which cellulose acetate was grafted using vinyltrimethoxysilane (VTMS), then hydrolyzed and condensed to form a polymer network. PDMC was also covalently crosslinked to enhance its performance. GCV-Modified CA showed significant performance improvements for H₂S and CO₂ removal; the permeability of CO₂ and H₂S were found to be 139 and 165 Barrer, respectively, which represented a 30X and 34X increase compared to the pristine CA polymer. The H₂S/CH₄ and CO₂/CH₄ ideal selectivities were found to be 39 and 33, respectively. Crosslinked PDMC showed a higher CO₂/CH₄ selectivity of 38 with a better plasticization resistance for CO₂ and H₂S.
In the third objective, these materials were tested under aggressive ternary mixtures of H₂S/CO₂/CH₄ with both vacuum and nonvacuum downstream. Even under aggressive feed conditions, GCV-Modified CA showed better performance vs. PDMC, and it remained were fairly stable, making it a potential candidate for aggressive sour gas separations, not only because of its significantly higher productivity, which will help decrease the surface area needed for separation, thereby reducing operating costs, but also because of the lower cost of the raw material GCV-Modified CA compared to PDMC.
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Mahajan, Rajiv. "Formation, characterization and modeling of mixed matrix membrane materials /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004329.
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Tomasa, Tina. "Development of Membrane Materials for Gas-liquid Membrane Contactors for CO2 Capture from Natural Gas." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22777.
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In this work, membrane materials are developed with the purpose to be used in a gas-liquid membrane contactor for CO2 capture from natural gas. The amine, methyl diethanolamine (MDEA), is to be used in the liquid phase as the absorbent. This requires a hydrophobic membrane material with high permeabilities and good compatibility with the absorption liquid.Poly(1-trimethysilyl-1-propyne) (PTMSP) is a glassy, high free volume polymer, which achieves the highest gas permeabilities of al known polymers. The permeabilities are however known to be unstable over time due to physical aging of PTMSP. Thermal crosslinking of PTMSP with the bis(azide) 4,4-diazidobenzophenone (BAA) has showed to increase the membrane?s chemical and physical stability. Crosslinking increased the resistance towards solvents such as toluene. The gas permeabilities of the membranes were tested for three different gases: N2, CH4 and CO2 at 2, 4 and 6 bar. The gas permeability decreased upon crosslinking but was stable with time. This decrease in permeability is related to the decrease in fractional free volume (FFV) upon crosslinking. Addition of nanoparticles have shown to increase the permeabilities again. Referring to the project work from the fall 2012, addition of nanoparticles of the size 15 nm decreased the permeabilities. They might have blocked the free volume. Clusters (1-3 µm) of TiO2 nanoparticles with the primary size 21 nm was used in this work and showed promising results as the permeability increased with increasing nanoparticle content. Several membranes of pure PTMSP, crosslinked PTMSP, and crosslinked nanofilled PTMSP membranes were exposed to distilled water, 2M MDEA and 4.2M MDEA up to 10 weeks (4 weeks for crosslinked nanofilled membranes). Permeation of pure PTMSP showed the same trend as the aging curve. Crosslinked PTMSP showed a decreasing trend the longer the membranes stayed in the solutions. Based on the selectivities, this trend might have been caused by the reduction in the solubility coefficients. Crosslinked nanofilled membranes on the other hand, showed approximate 90% lower permeability than corresponding membranes which have not been in contact with any solutions. Fourier Transform Infrared (FT-IR) spectroscopy was used to characterize the membrane materials to see the presence of chemical groups and to see how they change upon crosslinking. FT-IR spectra of PTMSP with BAA showed a peak at 2122 cm-1 (azide group), which disappeared after thermal crosslinking of the membrane. This leaves BAA with a reactive bis(nitrene) that is ready to bond with PTMSP. Microscopic pictures have shown how the free volume in crosslinked membrane decreases as the content of BAA increases.Other characteristic methods like contact angle measurements were used. The requirements are a hydrophobic material, which indicate that the liquid should not wet the surface (contact angle > 90°). The water contact angles were above 90°. Membranes exposed to solutions showed that the highest contact angles were observed for membranes soaked in 4.2M MDEA, followed by 2M MDEA. The viscosity of polymer solutions were found by using a rheometer and the results were correlated to the permeabilities. Thermogravimetric analysis (TGA) showed thermal degradation of PTMSP at 350°C.
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Cohen-Tanugi, David. "Nanoporous graphene as a water desalination membrane." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98743.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 147-162).
Desalination is one of the most promising approaches to supply new fresh water in the face of growing water issues. However, commercial reverse osmosis (RO) techniques still suffer from important drawbacks. In order for desalination to live up to the water challenges of this century, a step-change is needed in RO membrane technology. Thanks to significant advances in the field of computational materials science in the past decade, it is becoming possible to develop a new generation of RO membranes. In this thesis, we explore how computational approaches can be employed to understand, predict and ultimately design a future generation of RO membranes based on graphene. We show that graphene, an atom-thick layer of carbon with exceptional physical and mechanical properties, could allow for water passage while rejecting salt ions if it possessed nanometer-sized pores. Using computer simulations from the atomic scale to the engineering scale, we begin by investigating the relationship between the atomic structure of nanoporous graphene and its membrane properties in RO applications. We then investigate the thermodynamics, chemistry and mechanics of graphene and the water and salt surrounding it. Finally, we establish the system-level implications of graphene's promising membrane properties for desalination plants. Overall, this thesis reveals that graphene can act as an RO membrane with two orders of magnitude higher water permeability than commercial polymer membranes as long as the nanopores have diameters around 0.6nm, that graphene is strong enough to withstand RO pressures as long as it is supported by a substrate material with adequate porosity, and that a nanoporous graphene membrane could ultimately reduce either the energy footprint or the capital requirements of RO desalination. Ultimately, this thesis highlights a path for the development of next-generation membranes for clean water production in the 21st century.
by David Cohen-Tanugi.
Ph. D.
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Cheng, Wei. "Pretreatment and enzymatic hydrolysis of lignocellulosic materials." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1951.
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Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains xii, 173 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 138-142).
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Brunello, Giuseppe. "Computational modeling of materials in polymer electrolyte membrane fuel cells." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48937.
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Fuel cells have the potential to change the energy paradigm by allowing more efficient use of energy. In particular, Polymer Electrolyte Membrane Fuel Cells (PEMFC) are interesting because they are low temperature devices. However, there are still numerous challenges limiting their widespread use including operating temperature, types of permissible fuels and optimal use of expensive catalysts. The first two problems are related mainly to the ionomer electrolyte, which largely determines the operating temperature and fuel type. While new ionomer membranes have been proposed to address some of these issues, there is still a lack of fundamental knowledge to guide ionomer design for PEMFC.
This work is a computational study of the effect of temperature and water content on sulfonated poly(ether ether ketone) and the effect of acidity on sulfonated polystyrene to better understand how ionomer material properties differ. In particular we found that increased water content preferentially solvates the sulfonate groups and improves water and hydronium transport. However, we found that increasing an ionomer’s acid strength causes similar effects to increasing the water content.
Finally, we used Density Functional Theory (DFT) to study platinum nano-clusters as used in PEMFCs. We developed a model using the atom’s coordination number to quickly compute the energy of a cluster and therefore predict which platinum atoms are most loosely held. Our model correctly predicted the energy of various clusters compared to DFT. Also, we studied the interaction between the various moieties of the electrolyte including the catalyst particle and developed a force field.
The coordination model can be used in a molecular dynamics simulation of the three phase region of a PEMFC to generate unbiased initial clusters. The force field developed can be used to describe the interaction between this generated cluster and the electrolyte.
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Rocheleau, Marie-Josée. "Investigation of membrane materials for solid-state, ion-selective electrodes." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74675.
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The preparation and characterization of new materials to make ion-selective membranes are described. The usefulness of zinc orthophosphate and zinc mercuric thiocyanate to make a carbon-support electrode responsive to zinc was investigated. Better results were obtained with zinc orthophosphate. However, the electrode response was lowered by the formation of acidic oxides on the surface of the electrode, and interferences from copper(II), lead(II), and cadmium(II) were observed. An indirect potentiometric method based on the selective monitoring of chlorozincate(II) or cyanozincate(II) anions with a coated-wire ion-selective electrode was proposed as an alternative for monitoring zinc ion. The application of quaternary ammonium, phosphonium, and alkyl phosphate ionic polymer membranes to potentiometric and voltammetric analysis was also studied. Ionic polymer membranes offer a number of advantages, namely improved membrane lifetime and enhanced adherence to solid-substrate electrodes, when compared to conventional ion-selective membranes. The last stage of this research focused on the application of ionic polymer membrane electrodes in flow injection analysis.
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Kocsis, Istvan. "Supramolecular artificial water channels : from molecular design to membrane materials." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT200/document.
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Le travail décrit dans cette thèse couvre une étude fondamentale sur des canaux artificiels d'eau et sur des matériaux membranaires incorporant ces canaux. Structuré en quatre chapitres, la thèse commence par une présentation de l'état de l’art sur les systèmes biomimétiques de transport d'eau et des membranes biomimétiques. Au centre de tous ces travaux de recherche sont les protéines biologiques hautement efficaces et sélectives, les Aquaporines. Le deuxième chapitre présente les canaux artificiels d'eau à base d'imidazole-quartet. Les similitudes structurelles et fonctionnelles avec les Aquaporines sont discutées et caractérisées par plusieurs méthodes expérimentales. Les structures à l'état solide obtenues à partir de monocristaux présentent une organisation très similaire des I-quartets avec leurs homologues biologiques. Le biomimétisme fonctionnel du transport de l'eau a été démontré par des expériences cinétiques de transport à travers des systèmes vésiculaires. Le mécanisme de translocation de l'eau et l'organisation confinée dans des environnements lipidiques a été confirmé par des simulations dynamiques moléculaires, tandis que la preuve physique de l'eau orientée dipolaire dans les canaux intégrés aux lipides a été fournie par des expériences de spectroscopie IR polarisée. Le troisième chapitre présente de nouveaux canaux d'eau artificiels en utilisant une stratégie d'auto-assemblage. De nouveaux composés à base de diol, de tétrazacrown et de tryarilamine capables de transporter l'eau sont décrits. Le dernier chapitre décrits le passage du niveau moléculaire aux matériaux membranaires macroscopiques incorporant des canaux d'eau artificiels. Deux configuration membranaires différentes ont été décrites: des membranes en couche mince par l'incorporation de nanoparticules à base d'imidazole dans des polymères de polyamide et des membranes de la cellulose régénérée chimiquement greffée par des monomères de canaux d'eau artificiels. Les membranes ont été caractérisées par diverses méthodes d'imagerie et d'analyse et leurs performances ont été testées dans des expériences d'osmose inverse et de filtration d'osmose directe. La thèse est conclue avec une partie de conclusion générale, comprenant des perspectives pour les développements futursThe work described in this thesis covers an in depth fundamental study of artificial water channels and of membrane materials incorporating these channels. Structured in four chapters, the thesis begins with a presentation of the state of the art in the field of biomimetic systems and membranes for water transport. The center of the described research work is the family of highly efficient and selective biological water transporter proteins, the Aquaporins. The second chapter presents the description of imidazole-quartet supramolecular artificial water channels. Structural and functional similarities with Aquaporins are discussed and based on several experimental methods. Single-solid state structures present very similar organization of confined water wires as found in their biological counterparts. Functional mimicry of water transport has been proved through stopped flow experiments in vesicular systems. Further characterization concerning water translocation mechanism and confined organization in lipid environments have been obtained through molecular dynamic simulations, while physical evidence of dipolar oriented water in lipid embedded channels has been provided by sum frequency generation experiments. The third chapter presents novel artificial water channels. New diol, tetrazacrown and tryarilamine based compounds have been described, with a main focus on design, synthesis, self-assembly and water transport properties. The last chapter makes the transition from the molecular systems to macroscopic membrane materials incorporating artificial water channels. Two different approaches have been described: thin film nanocomposite membranes based on the incorporation of imidazole-quartet nanoparticles in polyamide polymers and chemically grafted regenerated cellulose membrane through the use of custom monomers for the obtaining of artificial water channels. The membranes have been characterized through various imaging and analytical methods and their performances have been tested in reverse and forward osmosis experiments. The thesis is concluded with a general conclusion part, including perspectives for future developments
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Liu, Yang. "Photoelectrochemical cell constructed from BBY membrane with various substrate materials." VCU Scholars Compass, 2017. http://scholarscompass.vcu.edu/etd/4999.
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Photoelectrochemical cells have been intensively studied in recent years with regard to using thylakoid and photosynthesis system I/II. BBY membrane is another protein complex that has potential to be utilized to build photoelectrochemical cells. Within the BBY membrane lies the highly active photosynthesis system II complex, which upon light activation, generates electrons transported within the electron transport chain during photosynthesis in green plants. This study presents an approach of immobilizing thylakoid or BBY membrane onto gold nanoparticle modified gold plate or multi-walled carbon nanotube (MWCNT) modified indium tin oxide vi (ITO) coated glass substrate. The results show that BBY membrane has higher activity with a value of 168 ± 12 μmol DCIP/(mg Chl*hr) than the thylakoid, which has an activity of 67 ± 7 μmol DCIP/(mg Chl*hr). Further amperometric tests also show that BBY membrane generates a higher current than the thylakoid. We used gold based materials to build the cell first since gold has high electrical conductivity. However, in order to minimize the construction cost of cells, relatively cheap materials such as ITO coated glass and MWCNT were used instead. The surface morphology of cells was characterized using atomic force microscope (AFM) throughout cell modification. When comparing to the cell with gold material, the cell constructed with ITO and MWCNT generated a higher current density. The highest current density was found as 20.44 ± 1.58 μA/cm2 with a system of ITO/MWCNT/BBY. More, the stability of the system was examined and the result shows a decreasing rate of 0.78 %/hour.
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Hassanpouryousefi, Sina. "Modeling Electrospun Fibrous Materials." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6109.
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Electrospinning has been the focus of countless studies for the past decades for applications, including but not limited to, filtration, tissue engineering, and catalysis. Electrospinning is a one-step process for producing nano- and/or micro-fibrous materials with diameters ranging typically from 50 to 5000 nm. The simulation algorithm presented here is based on a novel mass-spring-damper (MSD) approach devised to incorporate the mechanical properties of the fibers in predicting the formation and morphology of the electrospun fibers as they travel from the needle toward the collector, and as they deposit on the substrate. This work is the first to develop a physics-based (in contrast to the previously-developed geometry-based) computational model to generate 3-D virtual geometries that realistically resemble the microstructure of an electrospun fibrous material with embedded particles, and to report on the filtration performance of the resulting composite media.
In addition, this work presents a detailed analysis on the effects of electrospinning conditions on the microstructural properties (i.e. fiber diameter, thickness, and porosity) of polystyrene and polycaprolactone fibrous materials. For instance, it was observed that porosity of a PS electrospun material increases with increasing the needle-to-collector distance, or reducing the concentration of PS solution. The computational tool developed in this work allows one to study the effects of electrospinning parameters such as voltage, needle-to-collector distance (NCD), or polymer concentration, on thickness and porosity of the resulting fibrous materials. Using our MSD formulations, a new approach is also developed to model formation and growth of dust-cakes comprised of non-overlapping non-spherical particles, for the first time. This new simulation approach can be used to study the morphology of a dust-cake and how it impacts, for instance, the filtration efficiency of a dust-loaded filter, among many other applications.
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Hassan, Hussein Abdel Aziz Hany. "Development of hybrid silica membrane material for molecular sieve applications." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/125069.
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El desarrollo de nuevas membranas de sílice ha ido ganando cada vez más importancia en los últimos años. Se propone una nueva metodología para la modificación del material de membrana de sílice. Un nuevo material de membrana de sílice hidrófobico y dopado con cobalto ha ido desarrollado. El nuevo material se preparó por la hidrólisis catalizada por ácido y el proceso de condensación de ortosilicato de tetraetilo (TEOS) y metiltrietoxisilano (MTES). Los resultados mostraron que la estabilidad térmica del nuevo material se ve reforzada por proceso de dopaje con cobalto. Se logró un material de membrana de sílice microporosa hidrófoba con alta estabilidad térmica de hasta 560 °C en atmósfera oxidante y una distribución de tamaño de poro estrecha. El nuevo material se usó para la preparación de nuevas membranas. Las membranas híbridas dopadas con cobalto mostraron mejores resultados en comparación con las híbridas no dopadas respeto la selectividad de los gases.Development of new silica membranes properties, e.g., molecular sieving properties, has been increasingly gaining importance in the last few years. A new methodology for modification of silica membrane material is proposed. A novel silica membrane material, referred to as hydrophobic metal-doped silica, was developed by cobalt-doping within the organic templated silica matrix (hybrid silica). The novel material was prepared by the acid-catalyzed hydrolysis and condensation process of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES). The results showed that the thermal stability of the organic templated silica matrix was enhanced by cobalt-doping process. A hydrophobic microporous silica membrane material with high thermal stability up to 560 °C in oxidizing atmosphere and a narrow pore size distribution was achieved. The novel material was used for preparation of novel supported silica membranes. The cobalt-doped hybrid membranes showed better results compared with the non-doped hybrid one concerning the ideal selectivity of gases.
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Zhou, Bo Ph D. Massachusetts Institute of Technology. "Simulations of polymeric membrane formation in 2D and 3D." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/35312.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 207-213).
The immersion precipitation process makes most commercial polymeric membranes, which enjoy widespread use in water filtration and purification. In this work, a ternary Cahn-Hilliard formulation incorporating a Flory-Huggins homogeneous free energy function is used to model both initial diffusion and the liquid-liquid demixing stage of the immersion precipitation process, which determines much of the final morphology of membranes. Simulations start with a simple non-solvent/solvent/polymer ternary system with periodic boundary conditions and uniform initial conditions with small random fluctuations in 2D. Results in 2D demonstrate the effects of mobilities (Mij) and gradient penalty coefficients (Kij) on phase separation behavior. A two-layer polymer-solvent/non-solvent initial condition is then used to simulate actual membrane fabrication conditions. 2D simulation results demonstrate an asymmetric structure of membrane morphology, which strongly agrees with the experimental observation. A mass transfer boundary condition is developed to model the interaction between the polymer solution and the coagulation bath more efficiently. Simulation results show an asymmetric membrane with connected top layer.
(cont.) Then a wide range of initial compositions are used in both the polymer solution and the coagulation bath, and the resulting morphology changes from isolated polymer droplets to bi-continuous pattern to continuous polymer with isolated pores. A nonuniform initial condition is proposed to model the evaporation of volatile solvent prior to immersion, which results in different time scale of the onset of spinodal decomposition and an asymmetric structure with different pore size in the membrane. Furthermore, a simple one-factor model is used to capture the concentration dependence of the polymer mobility in the low concentration range. Simulations with variable polymer mobility show faster coarsening kinetics. The membrane simulations are then extended to three dimensions. The 3D simulations show similar morphology as 2D results: an asymmetric structure with a dense layer on top of a porous bulk, but provide more information about the pore connectivity. The coarsening mechanism study confirmed the merge of the layers into the bulk membrane structure..
(cont.) Finally, ternary Cahn-Hilliard equations are coupled with the Navier-Stokes equations to include fluid flow driven by the interface curvature change during spinodal decomposition in two dimensions. Different formulation of the Navier-Stokes equation are evaluated for computational efficiency. 2D simulation results show that fluid flow destabilizes the top layer of membrane.
by Bo Zhou.
Ph.D.
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Cohen-Tanugi, David H. (David Henri Michaël). "Nanoporous graphene as a desalination membrane : a computational study." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/76129.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 19-21).
With conventional water sources in short and decreasing availability, new technologies for water supply have a crucial role to play in addressing the world's clean water needs in the 21st century. In this thesis, we examine how nanometer-scale pores in single-layer freestanding graphene can effectively filter NaCl salt from water. Using classical molecular dynamics, we report the desalination performance of such membranes as a function of pore size, chemical functionalization, and applied pressure. Our results indicate that the membrane's ability to prevent the salt passage depends critically on pore diameter, with pores in the 0.7-0.9 nm range allowing for water flow while blocking ions. Further, an investigation into the role of chemical functional groups bonded to the edges of graphene pores suggests that commonly occurring hydroxyl groups can roughly double the water flux thanks to their hydrophilic character. The increase in water flux comes at the expense of less consistent salt rejection performance, which we attribute to the ability of hydroxyl functional groups to substitute for water molecules in the hydration shell of the ions. Overall, our results indicate that the water permeability of this material is several orders of magnitude higher than conventional reverse osmosis membranes, and that nanoporous graphene may have a valuable role to play for water purification.
by David H. Cohen-Tanugi.
S.M.
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Pang, Shing Kin. "Development of a low-cost membrane with used non-woven material for wastewater treatment /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202006%20PANG.
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Cheung, Clement. "Studies of the nitration of cellulose - application in new membrane materials." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46048.
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Leitch, Megan. "Quantitative Structure-Flux Relationships of Membrane Distillation Materials for Water Desalination." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/780.
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Membrane distillation (MD) is an emergent water desalination technology with potential for scalable, sustainable production of fresh water from highly concentrated brines. Wider adoption of MD technology depends upon improvements to process efficiency. In recent years, researchers have published a number of experimental papers seeking to improve mass and heat transport properties of MD membranes. However, an imperfect understanding of how intrinsic membrane geometry affects MD performance limits efforts to optimize membrane structure. The objective of this dissertation is to help elucidate effects of membrane structure on MD flux, permeability, and thermal performance, with a focus on novel fibrous membranes. Mechanistic and empirical modeling methods were employed to relate the structural characteristics of bacterial nanocellulose and electrospun polymeric membranes to experimentally-measured MD performance. Through these experimental and modeling studies, three conclusions are reached. First, the MD community can hasten the search for optimal membrane structures by improving the quality and reproducibility of reported experimental data. Review of published and newly-collected MD data shows that feed and permeate stream channel geometry and flow non-idealities can substantially affect measured performance metrics for MD membranes. If these factors are accounted for by careful characterization of convective heat transfer coefficients, membrane permeability and thermal efficiency can be definitively deduced. A new methodology is presented for determining convective heat transfer coefficient using experimentally-validated Nusselt correlations. Accurate reporting of cassette heat transfer metrics will facilitate inter-study experimental reproducibility and comparison. Second, use of dimensional analysis to empirically model MD transport is effective for predicting vapor flux in fibrous membranes. Advantages of the model include its use of easily-measurable structural parameters tailored specifically for fibrous membranes and the incorporation of all relevant vapor, membrane, and system characteristics into a mathematically simple, yet theoretically sound, regression model. The new model predicts MD flux more accurately than the mechanistic Dusty Gas Model or previously published empirical MD models. Dimensional-analysis-based transport models may be generalizable for a variety of novel membrane types, lead to a more rigorous understanding of structural influences on vapor transport processes, and guide the development of high-performance membrane structures. Finally, MD process efficiency can benefit by development of highly porous, scalable membrane materials. Bacterial nanocellulose aerogel membranes exhibit substantial improvements in intrinsic permeability and thermal efficiency as compared to traditional phase-inversion membranes, suggesting that there is an opportunity to advance MD process viability through improved membrane design. By mimicking the porosity and pore-interconnectivity of nanocellulose aerogels, novel membrane materials can achieve high thermal efficiency and low mass transport resistance. This dissertation contributes experimental data and modeling techniques to improve knowledge of membrane structural effects on MD performance. These contributions have implications for the wider adoption of MD technology through better reproducibility of published experimental results, enhanced transport modeling to optimize membrane structure, and demonstrated thermal efficiency of a highly porous materials.
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Dimitriadou, Eleni Anastasia. "Experimental assessment and thermal characterisation of lightweight co-polymer building envelope materials." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675716.
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Co-polymer facade materials have recently become a popular option in the building industry as an alternative to glazing. Ethylene Tetra-Fluoro-Ethylene (ETFE) foil has been successfully used in many projects as an innovative solution to energy-conscious design challenges. In addition, the use of ETFE membrane has resulted in significant savings in cost and structural support requirements, compared with conventional glazing, due to its low weight. There is a lack of detailed published data reporting its thermal behaviour. This study focuses on the examination of heat transfer through the ETFE membrane, and more specifically heat loss and solar gains. The document examines the impact of the material on the energy use of a building, as well as thermal comfort and interior conditions. Through field-testing and computer simulations the research evaluates the material’s thermal properties to obtain results that will assist in estimating the suitability of ETFE foil use in comparison to glass. Field-testing is used to perform a comparison of the thermal and energy behaviour of a fritted double ETFE cushion to a double glazed cover. The two experimental devices under examination present nearly identical energy consumption due to heating requirements. The experimental findings are implemented in Integrated Environmental Solutions (IES) and used to identify the necessary steps to accurately reproduce the thermal and energy behaviour associated with both covering materials. Further simulations were undertaken to provide a comparison of several types of ETFE cushions to various types of double glass. More specifically, the types examined are a clear double ETFE roof cover and a fritted double ETFE roof cover in comparison to a standard double glazed roof and a low-E double glazed roof. The roofs covers are examined in relation to energy requirements for both the heating and cooling of a space. Such an assessment of performance will provide information for further investigation to improve the material’s features and optimise energy performance.
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Villar, Gabriel. "Aqueous droplet networks for functional tissue-like materials." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:602f9161-368c-48c0-9619-7974f743f2f2.
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An aqueous droplet in a solution of lipids in oil acquires a lipid monolayer coat, and two such droplets adhere to form a bilayer at their interface. Networks of droplets have been constructed in this way that function as light sensors, batteries and electrical circuits by using membrane proteins incorporated into the bilayers. However, the droplets have been confined to a bulk oil phase, which precludes direct communication with physiological environments. Further, the networks typically have been assembled manually, which limits their scale and complexity. This thesis addresses these limitations, and thereby enables prospective medical and technological applications for droplet networks. In the first part of the work, defined droplet networks are encapsulated within mm-scale drops of oil in water to form structures called multisomes. The encapsulated droplets adhere to one another and to the surface of the oil drop to form interface bilayers that allow them to communicate with each other and with the surrounding aqueous environment through membrane pores. The contents of the droplets can be released by changing the pH or temperature of the surrounding solution. Multisomes have potential applications in synthetic biology and medicine. In the second part of the work, a three-dimensional printing technique is developed that allows the construction of complex networks of tens of thousands of heterologous droplets ~50 µm in diameter. The droplets form a self-supporting material in bulk oil or water analogous to biological tissue. The mechanical properties of the material are calculated to be similar to those of soft tissues. Membrane proteins can be printed in specific droplets, for example to establish a conductive pathway through an otherwise insulating network. Further, the networks can be programmed by osmolarity gradients to fold into designed shapes. Printed droplet networks can serve as platforms for soft devices, and might be interfaced with living tissues for medical applications.
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Rose, Ian James. "Triptycene-based polymers of intrinsic microporosity for membrane applications." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25440.
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This project was focused on the synthesis of novel Polymers of Intrinsic Microporosity (PIMs) that are soluble in common low boiling point solvents so that self-standing films can be prepared for gas permeability measurements. The common building unit of these novel PIMs was triptycene and its derivatives. Modification of these triptycene compounds enabled the alteration of the polymeric backbone, so that we could tune the gas permeability properties. Modifications included the substitution of different functional groups (e.g. addition of methyl groups) and also the extension via benzoannulation of the triptycene structure. The synthesis of the PIMs was based around three different polymerisation techniques. The first one involved the formation of triptycene-based polyimides (PIs) using a triptycene based dianhydride, prepared in a multistep synthesis. Shorter and cheaper synthetic routes were attempted, but all to no avail. The resulting triptycene monomer was reacted with a variety of commercial and non-commercial bisanilines for the formation of several PIM-PIs, all exhibiting different performances. Robust self-standing films were obtained for two of these PIM polyimides. In addition to the formation of polyimides, the synthesis of Tröger’s Base (TB) polymers, also based on triptycene components, were achieved. This type of polymerisation involves the reaction between a “bisaniline” monomer and a source of “formaldehyde”, such as dimethoxymethane (DMM), in a strong acid media, typically trifluoroacetic acid (TFA). Modification of these triptycene-based bisanilines has led to the formation of TB-PIMs, all with distinctive gas permeation properties. TB-PIM copolymers (reaction between two different bisaniline monomers with DMM and TFA) were synthesised in an attempt to further tune the performance of the polymers. Finally, the preparation of polybenzodioxan polymers based around extended triptycene monomers (i.e. benzotriptycenes) was studied. By using a variety of substituted benzotriptycene biscatechol monomers and performing the polymerisation using tetrafluoroterephthalonitrile, in the presence of K2CO3, the synthesis of a series of substituted benzotriptycene polybenzodioxane polymers was successfully achieved and the polymers showed enhanced gas permeation properties.
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Ma, Jia. "Development of Cost-Effective Membrane-Electrode-Assembly (MEA) for Direct Borohydride Fuel Cells." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1326302289.
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Greene, George W. IV. "Surface modification of sintered porous polyethylene membrane." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/20126.
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Muya, Francis Ntumba. "Hydrophilic Polysulfone-Hydrogel Membrane Material for Improved Nanofiltration in Wastewater Treatment." University of the Western Cape, 2013. http://hdl.handle.net/11394/4274.
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>Magister Scientiae - MScOver the last decade polysulfone membranes have been demonstrated to be one of the best membrane types in wastewater treatment, especially in ultrafiltration, owing to its mechanical robustness, structural and chemical stability. Regrettably these membranes are mostly hydrophobic by nature and therefore highly vulnerable to fouling due to chemosorptive mechanisms. Fouling may be caused by cake formation on the surface of the membrane or by surface assimilation of the foulants. Many studies have been directed at improving hydrophilic properties of polysulfone membranes by introducing different types of nanoparticle composite such as TiO2, ZnO2, Au and Ag nanoparticles to the polymer matrix, in order to reduce fouling potential and increase membrane performance. In the present investigation a hydrogel material was developed by crosslinking polyvinyl alcohol (PVA) with polysulfone (PSF), using glutaraldehyde as crosslinker. PVA has excellent film formation, emulsifying and adhesive properties, it is highly flexible and has high tensile strength. Introducing PVA into the PSF polymer matrix was expected to impart its advantageous properties onto the resulting membrane and enhance hydrophilic characteristics of the membrane. The cross linking of PVA and PSF was controlled at three different ratios to evaluate the effect of the PSF contribution i.e. 25:75, 50:50 and 75:25. The crosslinked polymer composites produced three unique hydrogel materials, which were evaluated for the separation of selected small organic molecules, under hydrodynamic conditions, using rotating disk electrochemistry. The hydrogel thin film behaved as a chemical sensor for the oxidation of tannic acid in aqueous solution, with negligible shift in peak potential as a function of concentration. The nanomaterials prepared were characterised using spectroscopic, morphological and electrochemical techniques. Hydrogel performance in the presence of analyte molecule was evaluated by hydrodynamic voltammetry and electrochemical impedance spectroscopy. From calibration curves based on cyclic voltammetry, hydrodynamic, macroscopic and spectroscopic techniques, the 75% polysulfone and 25 % polyvinyl alcohol hydrogel (75:25 PSF-PVA) presented the best performance for quantitative detection and best sensitivity toward alginic acid and tannic acid than the corresponding composites (50:50 and 25:75 PSF-PVA). Optical results (contact angle) show an agreement with spectroscopic (EC) and microscopic (AFM) result. A decrease in contact angle gives an increase in roughness and diffusion coefficient. High surface roughness was linked to improved hydrophilicity of the polysulfone.
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Farr, Isaac Vincent. "Synthesis and Characterization of Novel Polyimide Gas Separation Membrane Material Systems." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/28590.
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Phenylindane monomers 5(6)-amino-1-(4-aminophenyl)-1,3,3-trimethylindane (DAPI), 5,6-diamino-1-(4-aminophenyl)-1,3,3-trimethylindane (TAPI) and 6-hydroxy-
1-(4-hydroxyphenyl)-1,3,3-trimethylindane (DHPI) were synthesized and characterized. DAPI, as well as other diamines, were then utilized in solution step polycondensation with a number of commercially available dianhydrides using either the two-step ester-acid solution imidization or the high temperature solution imidization routes. High molecular weight soluble fully cyclized polyimides were successfully synthesized using a 1:1 molar ratio of dianhydride to diamine. The polyimides were film forming and were characterized by size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and selective gas permeation methods, as well as other techniques. The O2 permeation and O2/N2 selectivity values obtained for materials prepared in this thesis are discussed in relation to the concept of an "upper bound", as defined in the literature concerning gas separation membranes.
The series of polyimides based on DAPI and several dianhydrides were found to have high glass transition temperatures (247°C-368°C) and very good short-term thermal stability as shown by TGA, despite the partially aliphatic character of DAPI. The 5,5'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis-1,3-isobenzenefurandione (6FDA)/DAPI system also exhibited low weight loss under nitrogen at 400°C, which was comparable to that of a wholly aromatic polyimide based on 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA)/4,4'-oxydianiline (ODA) which is known to have high thermal stability. In addition, the 6FDA/DAPI polyimides had a refractive index value of 1.571 from which the dielectric constant was calculated, giving an attractively low estimated value of 2.47.
The rigid, bulky and isomeric structure of DAPI in the repeat unit imparted film forming characteristics that allowed production of solvent cast membranes which displayed a range of O2 permeability and O2/N2 selectivity characteristics. High O2 permeabilities were observed for polyimides in which the DAPI structure predominated in relation to the overall polymer repeat unit, i.e. in combination with low molar mass dianhydrides. The more flexible dianhydrides afforded a greater degree of molecular freedom and were thought to result in a more tightly packed polymer conformation which decreased the rate of gas penetration through thin films. The DAPI/3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) system showed the best combination of O2 permeability and O2/N2 selectivity values (2.8Ba and 7.3, respectively). Modest variations in the DAPI isomeric ratio did not significantly effect the gas permselectivity properties.
High molecular weight polyimides based on DAPI and BTDA were synthesized by three different routes. The ester-acid and thermal imidization methods produced polyimides with the highest Tgs and best thermal stability in air, as compared to the chemical imidization procedure. For example, a Tg increase of 22°C and a 68°C increase in the 5% weight loss were found for the ester-acid imidized DAPI/BTDA polyimide over those found for the chemically imidized version. The higher Tg and 5% weight loss values were attributed to the elimination of residual uncyclized amide acid moieties.
Polyimides derived from 6FDA were synthesized by the high temperature solution imidization method. Thin films, cast from NMP, were tough and creasable and afforded high Tg (>295°C) systems with good thermal stability. When combined with rigid diamines, 6FDA contributed to high O2 permeation and moderate O2/N2 selectivity. The high O2 permeability was ascribed to hindered interchain packing attributed to the bulky CF3 groups. The exceptionally high oxygen permeability and O2/N2 selectivity values of the 9,9-bis(4-aminophenyl) fluorene (FDA)/6FDA system, were near the desirable "upper bound" for gas separation membrane materials, while those of 3,7-diamino-2,8-dimethyl-dibenzothiophene-5,5-dioxide (DDBT)/6FDA were actually above the upper bound.
High performance polymers based on 4,4'-bis [4-(3,4-dicarboxyphenoxy)]biphenyl dianhydride (BPEDA), 2,2'-bis [4-(3,4-dicarboxyphenoxy)phenyl] propane dianhydride (BPADA), 2,2-bis(3-amino-4-methylphenyl)hexafluoroisopropylidene dianhydride (Bis-AT-AF) and 3,7-diamino-2,8-dimethyl-dibenxothiophene-5,5-dioxide (DDBT) were also synthesized in this work. Additionally, they were characterized with regard to molecular weight, glass transition temperature, and thermal stability.
Polyimide systems containing hydroxyl moieties in the repeat unit were also investigated. Incorporation of hydroxyl moieties in the repeat unit enhanced chain stiffness via intermolecular hydrogen bonding and showed Tg increases of ~30°C Hydroxyl moieties also decreased the thermal stability values typically observed for polyimides. High O2/N2 selectivity was achieved with all of the 4,4'-diaminobiphenyl-3,3'-diol (HAB) containing polymers. However, these materials also had low O2 permeabilities, which suggested a tightly packed structure, possibly facilitated by hydrogen bonding. In contrast to suggestions in the literature, the comparison between a polyimide having pendant hydroxyl groups and another having the same repeat unit without them did not reveal a significant change in permselectivity behavior.
The synthesis, characterization and crosslinking behavior of functional polyimides containing phenol, amine and acetylene moieties are also described. A crosslinking reaction of oligomers containing phenol moieties with a tetrafunctional epoxy resin was achieved 100°C below the "dry" glass transition temperature and was attributed to residual solvent. Utilization of this crosslinking mechanism could allow membrane optimization by investigating the influence of a number of variables, such as the concentration of the phenolic moiety, epoxy weight percent, catalyst concentration and residual solvent content.Ph. D.
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Zhou, Xiongtu. "Investigation of cell-material interaction using topographical patterns and cell imprinting techniques." Paris 6, 2010. http://www.theses.fr/2010PA066599.
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Améliorer la connaissance des interactions cellules-matériau est un enjeu crucial pour la biologie cellulaire et l’ingénierie tissulaire ainsi que pour la fabrication de dispositifs biomédicaux élaborés. Ce travail de thèse s’est basé sur le développement de technologies de micro- et nanofabrications avancées et de l’imagerie cellulaire de haute résolution, afin d’obtenir une vue plus claire sur les phénomènes d’élongation, alignement, extention, et déformation locale de membrane cellulaire sur des motifs topographiques. La culture cellulaire sur des substrats comportant des trous et des sillons à dimensions micro et nanométriques a été étudiée, ce qui a permis de démontrer une forte dépendance de la géométrie des motifs et de la décoration de surface. En général, les membranes cellulaires sont localement déformées à cause de la présence des trous ou des sillons micrométriques, qui aident, entre autre, l’attachement et l’adhésion cellulaire. Nous avons aussi noté que les cellules cancereuses sont plus agressives pour exploiter les motifs topographiques. Enfin, nos études ont été élargies à des motifs de géometrie plus complexe tels que des réseaux de microsillons croisés avec des différentes périodicités et profondeurs de gravure.
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Kinney, Chris 1982. "Water modeling the solid oxide membrane electrolysis with rotating cathode process." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32729.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2004.Vita.
Includes bibliographical references (leaf 35).
The Kroll process for refining titanium is an expensive batch process which produces a final product that still requires intensive post processing to create usable titanium. A new process, Solid Oxide Membrane Electrolysis with Rotating Cathode (SOMERC) process is being explored. The SOMERC process is a continuous process that could produce large quantities of high quality titanium at a fraction of the cost of the Kroll process. This paper examines the fluid flow around the ingot in the SOMERC Process. A large shear between the ingot and surrounding fluid will create a fully-dense ingot instead of dendrites, because dendrites are undesirable. Using a camera, a plane of light and titanium dioxide particles, videos and pictures of the water were taken and analyzed to find how to create a large amount of shear between the ingot and the fluid. Out of the speeds tested, a rotation rate of 900Ê»/s for the ingot proved to create the most shear, and therefore the shear between the ingot and fluid increases with increasing rotation rate, making it more likely to suppress the formation of dendrites.
by Chris Kinney.
S.B.
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Pécanac, Goran [Verfasser]. "Thermo-mechanical investigations and predictions for oxygen transport membrane materials / Goran Pécanac." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1033682071/34.
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Meoto, L. "Controlled synthesis and characterization of hierarchically structured inorganic materials for membrane applications." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1500936/.
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There is great need for new ways to effectively purify and desalinate water. There are protein channels in cell walls that act as very efficient water desalination membranes by rapidly and selectively transporting water. The mechanism of these biological membranes could be implemented in the design of a synthetic membrane by creating a size and electrostatic barrier suitable for efficient water desalination. Ordered mesoporous silica is a particularly attractive material, with ordered arrays of uniform nanochannels of a controllable size that have a wide range of applications, including separations. The silica surface can easily be functionalized to create the required steric and electrostatic effects. The synthesis of mesoporous silica films typically leads to pores that are poorly accessible from the film surface, hindering membrane applications. This thesis explores the formation of mesoporous silica structures within vertically aligned channels of anodic alumina membranes, so that an externally accessible pore orientation is obtained. These mesoporous structures are grown via an aspiration method. The thesis examines the influence of experimental conditions on the confined growth of the silica structures. Surfactants P123 and F127 act as structure directing agents, yielding circular, columnar or lamellar structures, such as 2D hexagonal (P123) and 3D cubic (F127), within the alumina channels. Ordered mesoporous silica in the confined space is achieved by controlling ethanol content. Transitions between the mesophases and changes in textural properties are observed with variations in experimental parameters. These experiments reveal that obtaining a defect-free composite structure where the alumina channels are tightly filled with the mesoporous silica material is not as trivial as literature precedent would suggest. Challenges remain, which include filling the alumina channels uniformly and homogeneously, and detachment of silica from the alumina walls. Consequently, fabrication of a porous silicon membrane is explored as an alternative robust matrix for growing aligned ordered mesoporous silica.
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Lou, Yuecun. "Transport Modeling and CFD Simulation of Membrane Gas Separation Materials and Modules." University of Toledo / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1407020499.
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Rabie, Feras H. "Synthesis, Characterization, Membrane Fabrication and Gas Transport Behavior of Liquid Crystal Polymer Materials." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51962.
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A variety of liquid crystalline (LC) materials have been examined as potential membrane separation materials. The order present in the LC phases has measurable effects on solute sorption, diffusivity, permeability, and selectivity, and can thus be used to tune the transport and separation of different species. The current work has focused on polymer dispersed liquid crystal (PDLC), linear butadiene diol based side chain liquid crystalline polymer (LCP), and linear and crosslinked acrylate based LCP membranes. The focus was primarily on the separation of propylene and propane, a separation of significant industrial interest that is not easily achieved with current membrane technology.
Polysulfone (Psf) and 4-cyano-4'-octylbiphenyl (8CB) were used to fabricate polymer dispersed liquid crystal (PDLC) membranes. Permeation properties for propane and propylene through polysulfone membranes with increasing LC concentrations were measured at temperatures above and below the glass transition temperature and in several LC phases. The plasticization of PSf by 8CB increased permeability and selectivity with increasing temperatures below the Tg, and membranes with higher LC concentrations exhibited a higher mixed gas permeability and selectivity for propylene. Permeability selectivity decreased across the smectic to nematic phase transition. Overall, selectivities were low, and membrane stability was a significant problem, especially at higher pressures. Thus, several LCP systems were studies as candidates for membrane gas separations.
A side chain liquid crystalline poly(butadiene)diol with cyanobiphenyl mesogens was impregnated in a porous PTFE support for gas transport studies. Single gas sorption for propane and propylene in the LCP were investigated in the smectic A mesophase. Gas transport in the glassy state showed separation dominated by differences in gas diffusivity. Permeabilities and selectivities for propylene/propane in the liquid crystal mesophase increased with increasing temperature due to an increase in the segmental motional of the mesogenic units which facilitated solubility of propylene over propane. In addition, an increase solubility differences between propane and propylene were observed with an increase in feed pressure. Mixed gas permeability measurements resulted in an increase in selectivity both below and above the glass transition temperature due to competitive sorption of the two gases. The thermal behavior of liquid crystalline poly(butadiene)diols (PBDs) containing methoxy- or butoxy-substituted azobenzene side chains was studied. A strong dependence of the viscous and dynamic moduli of the polymer with respect to frequency and degree of modification was observed, but the results suggested that prolonged membrane stability for linear poly(butadiene)diol LCPs would be difficult to achieve. As a result, a new class of cross-linkable acrylate based side-chain LCPs was developed.
A mesogenic cyanobiphenyl based acrylate monomer, in combination with a non-mesogenic comonomers and a cross-linking agent, was used was used to fabricate stable cross-linked LCP films for membrane separation applications using an in situ free radical polymerization technique with UV initiation. To our knowledge, this is the first reported example of a crosslinked LCP membrane. Increasing the cross-linker content resulted in a decrease in mesogen order. At temperatures in the LC mesophase permeability selectivity for propylene over propane was derived from both solubility and diffusivity selectivity and was higher for the membrane with lower crosslinker content. An increase in the temperature causes a decrease in molecular ordering and consequently decreased permeability selectivity. At temperatures approaching the nematic/isotropic transition and above, the membrane with higher crosslinker content exhibited higher propylene selectivity. Mixed gas studies of propylene/propane resulted in higher selectivities compared to the single gas runs due to the decrease of propane permeability by the presence of propylene.Ph. D.
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Shin, Dong-Jae. "Performance and Usability of Flexible Membrane Keyboards." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/34003.
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Recently, many full-sized keyboards have been designed to fold in various ways in an attempt to make them more transportable. The flexible membrane keyboard, one type of full sized keyboard, is unique because it is made from silicon rubber, thus it is fully flexible and water resistant. Although a number of flexible keyboard characteristics are the same as standard keyboards (i.e. key size, shape and spacing), key-switch and key clicking mechanisms are inherently different. Since there is little or no existing research on flexible keyboards, there is a current need for data to facilitate design of such keyboards for use. Typing performance and perceived usability of several flexible keyboards that differed in terms of material hardness (hard, medium, or soft) and key contact point shape (circular or square) were studied. The results supported the hypothesis that both typing performance and usability of the flexible membrane keyboard were affected by material hardness and contact point shape. Square shaped contact points led to increased typing speed and decreased error rates, and medium or soft hardness led to increased typing speed. The best flexible keyboard (perceived by participants) in general received neutral usability ratings. However, ratings for mobility and design were much higher than neutral. Overall, subjective and objective measures of performance and usability indicated that flexible keyboards that are made of silicon of a soft or medium hardness and with a square shaped contact points are preferred.Master of Science
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Rieck, Daniel C. "MEMS fabricated nanopores and micropores functionalized with chromate-selective solvent polymeric membrane." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Thesis/Fall2008/d_rieck_012609.pdf.
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Thesis (M.S. in chemical engineering)--Washington State University, December 2008.Title from PDF title page (viewed on Apr. 10, 2009). "Department of Chemical Engineering." Includes bibliographical references.
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Van, Lehn Reid Chi. "Modeling the reaction mechanism of membrane penetration by striated amphiphitic gold nanoparticles." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58449.
Full textAbstract:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 37-38).
The desire to desire targeted drug delivery devices capable of releasing therapeutic payloads within the cytosol of cells has led to research on nanoparticles as suitable drug carriers. Recently, it was shown that gold nanoparticles coated in striped, alternating layers of hydrophobic and hydrophilic ligands are capable of non-disruptively penetrating a lipid bilayer, a discovery with potential implications in drug delivery. While the reaction mechanism is not known, initial experimental results indicate that endocytosis and membrane poration could be ruled as possible mechanisms. In this work, we explore the reaction mechanism of membrane penetration using a coarse-grained Brownian Dynamics model. We also define a Monte Carlo simulation for modeling ligand motion on the nanoparticle surface based on a single order parameter, and describe a method for approximating the interaction energy with the bilayer as a function of this parameter. Our simulations demonstrate the dependence of nanoparticles penetration on the surface mobility, not explicit conformation, of coated ligands. They demonstrate that while nanoparticles with static ligands in a striped conformation are unable to penetrate the bilayer, enabling surface mobility allows penetration by the induced formation of a small, transient pore of a comparable size to the nanoparticle. Our results offer an enhanced understanding of the nanoparticles-bilayer interaction and an identification of the property necessary for membrane penetration.
by Reid Chi Van Lehn.
S.B.
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Ganapathy, Visvanathan 1957. "Structural analysis of stretched membrane reflector modules using advanced composites." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276569.
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The concept of achieving low cost (≈ $20/m²) and ultra low weight (5 kg/m²) for heliostats is explored theoretically and experimentally. The objective of this work is to significantly improve the cost and performance of the structure under concern, without sacrificing strength and efficiency. The focus is on an innovative design of stretched-membrane heliostats. A reflective membrane of thin film is supported by a taut fishnet structural membrane consisting of graphite fiber-polymer matrix composite. The reflective and structural membranes are attached to a ring frame made of wood. The nonlinear problem of stress-strain analysis is formulated and solved using the finite-element code NASTRAN. The analysis is done for loads which include the initial stretching of the film and structural membrane and the pressure load due to wind. The scope of the present work is limited to analyzing the structural deformation behavior of flat-plate heliostats and partial extension to parabolic and semi-hemispherical dish reflectors.
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Chou, Berryinne. "Nano-Scale Modified Inorganic/Organic Hybrid Materials as Proton Conductors." Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1144419661.
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Wilkinson, James Daniel. "Imaging membrane potential." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:9496dc0b-212c-4355-830c-dbbcb5d7e581.
Full textAbstract:
Imaging membrane potential is a promising technique in the elucidation of the interactions of large networks of neurons. The membrane potential in a neuron varies as an action potential, the basic electrical signal of neuronal communication, travels along the length of the cell. Voltage sensitive dyes play a key role by providing an optical readout of the electric field generated across a neuron membrane by the action potential. However, none of the dyes reviewed in Chapter 1 generate sufficient signal change with changes in membrane potential; this sensitivity problem limits the ability of the imaging membrane potential technique to allow the high spatial and temporal resolution necessary for neuronal networks to be better understood. This thesis features two avenues of research that are expected to result in the necessary enhancements to voltage sensitive dyes to improve the signal change. The first avenue is based on the effect of an electric field upon the non-linear optical properties of a porphyrin macromolecule. The encouraging field sensitivity of a previous porphyrin monomer voltage sensor inspired an investigation which identified optimisations to enhance the voltage sensitivity (Chapter 2). The design, synthesis and initial characterisation of optimised porphyrin voltage sensors is detailed in Chapter 3. The second avenue is based on the effect of an electric field upon the rate of intermolecular electron transfer. In a suitably designed dye, the competition between electron transfer and fluorescence, following excitation by incoming light, allows the fluorescence intensity to act as an optical indicator of the electron transfer rate. New dyes were rationally designed and synthesised, as this effect had not been applied to voltage sensitive imaging before the research detailed in Chapter 4. The challenging purification of the new amphiphilic dyes synthesised also inspired research into a novel testing method which does not require amphiphilic dyes (Chapter 5).
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Schmidt, Bernd Ulrich Sebastian. "ACCESSING NOVEL MATERIAL PARAMETERS IN SINGLE CELL BIOMECHANICS." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191917.
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Die mechanischen Eigenschaften von Zellen charakterisieren und beeinflussen deren Zustand. Die vorliegende Arbeit zielt auf ein besseres Verständnis der biomechanischen Eigenschaften von Zellen ab. Der Fokus lag dabei auf der Biegesteifigkeit von Zellmembranen und der Deformierbarkeit der Zellen. Es werden drei Studien vorgestellt in der diese Materialparameter untersucht wurden.
Die erste Studie befasst sich mit der Temperaturabhängigkeit der mechanischen Eigenschaften. Hierbei wurden acht verschieden Zelllienien bei jeweils fünf Temperaturen rheologisch vermessen. Zur Messung wurde der sog. \"optical stretcher\" verwendet der gleichzeitig die Zellen deformieren und aufheizen kann. Die Versuche zeigen, dass eine Zeit-Temperatur superposition dabei nicht für alle Zelltypen funktioniert.
In der zweiten Studie wurden die Membransteifigkeit von Gewebeproben von Brust- und Gebärmutterhalskrebspatienten untersucht. Als Kontrollsystem wurde gutartiges Gewebe aus dem Umfeld des Tumors verwendet. Es konnte gezeigt werden, dass die Zellmembranen von Tumorzellen weicher waren als von gesundem Vergleichsgewebe. Die Änderung der Membrankomposition wurde dabei als mögliche Ursache massenspektroskopisch Untersucht und verschieden Ursachen der weichen Membrane diskutiert.
Für die dritte Studie wurde der chemische Wirkstoff Soraphen A eingesetzt um die Membransteifigkeit von zwei Zelllienien zu erhöhen. Dies zeigte eine Verringerung von Zellbeweglichkeit und Invasivität.
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Hirahara, Ann Satoko 1972. "Fabrication of sensitive high-temperature superconducting bolometers on a yttria-stabilized zirconia membrane." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32172.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1995.Vita.
Includes bibliographical references (leaves 37-38).
by Ann Satoko Hirahara.
M.S.
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Zou, Ying [Verfasser], Lorenz [Akademischer Betreuer] Singheiser, and Manja [Akademischer Betreuer] Krüger. "Thermomechanical characterization of advanced ceramic membrane materials / Ying Zou ; Lorenz Singheiser, Manja Krüger." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1161739602/34.
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Ylitervo, Päivi. "Concepts for improving ethanol productivity from lignocellulosic materials : encapsulated yeast and membrane bioreactors." Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3692.
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Lignocellulosic biomass is a potential feedstock for production of sugars, which can be fermented into ethanol. The work presented in this thesis proposes some solutions to overcome problems with suboptimal process performance due to elevated cultivation temperatures and inhibitors present during ethanol production from lignocellulosic materials. In particular, continuous processes operated at high dilution rates with high sugar utilisation are attractive for ethanol fermentation, as this can result in higher ethanol productivity. Both encapsulation and membrane bioreactors were studied and developed to achieve rapid fermentation at high yeast cell density. My studies showed that encapsulated yeast is more thermotolerant than suspended yeast. The encapsulated yeast could successfully ferment all glucose during five consecutive batches, 12 h each at 42 °C. In contrast, freely suspended yeast was inactivated already in the second or third batch. One problem with encapsulation is, however, the mechanical robustness of the capsule membrane. If the capsules are exposed to e.g. high shear forces, the capsule membrane may break. Therefore, a method was developed to produce more robust capsules by treating alginate-chitosan-alginate (ACA) capsules with 3-aminopropyltriethoxysilane (APTES) to get polysiloxane-ACA capsules. Of the ACA-capsules treated with 1.5% APTES, only 0–2% of the capsules broke, while 25% of the untreated capsules ruptured within 6 h in a shear test. In this thesis membrane bioreactors (MBR), using either a cross-flow or a submerged membrane, could successfully be applied to retain the yeast inside the reactor. The cross-flow membrane was operated at a dilution rate of 0.5 h-1 whereas the submerged membrane was tested at several dilution rates, from 0.2 up to 0.8 h-1. Cultivations at high cell densities demonstrated an efficient in situ detoxification of very high furfural levels of up to 17 g L-1 in the feed medium when using a MBR. The maximum yeast density achieved in the MBR was more than 200 g L-1. Additionally, ethanol fermentation of nondetoxified spruce hydrolysate was possible at a high feeding rate of 0.8 h-1 by applying a submerged membrane bioreactor, resulting in ethanol productivities of up to 8 g L-1 h-1. In conclusion, this study suggests methods for rapid continuous ethanol production even at stressful elevated cultivation temperatures or inhibitory conditions by using encapsulation or membrane bioreactors and high cell density cultivations.Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 4 april 2014, klockan 9:30 i KE-salen, Kemigården 4, Göteborg.
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Khasawneh, Qais Azzam. "On the Analysis of Mechanical Properties of Nanofiber Materials." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226939318.
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Nkosi, Mlungisi Moses. "Preparation and physico-chemical properties of nickel nanostructured materials deposited in etched ion-track membrane." Thesis, University of the Western Cape, 2005. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6214_1182749152.
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The development of finely dispersed powders and superfine-grained materials intended for application in various areas of science and engineering is one of the challenges facing modern nanotechnology. Thus, specific fundamental and applied research was required in order to consolidate advancement made in preparing nano- and submicron crystalline composite materials.
Useful templates for electrochemical deposition of nanowires include porous alumina films formed by anodic oxidation of aluminium, nuclear track-etched porous membranes, nanochannel array-glass and mesoporous channel hosts. The properties of the nanowires are directly related to the properties of the nanoporous templates such as, the relative pore orientations in the assembly, the pore size distribution, and the surface roughness of the pores. The template synthesis method, based on the use of porous polymeric and inorganic matrixes, is now actively used for synthesis of such composite materials. The method allows the chemical and/or electrochemical synthesis of nano- and microstructured tubes and wires consisting of conducting polymers, metals and semiconductors.
In this study various technological challenges relating to template synthesis and development of nickel nano- and microstructures on adequately strong and durable substrates were investigated. The two methods used were the electrochemical and chemical deposition. &ldquo
Hard nickel&rdquo
bath solution was used for optimal nickel deposition. This optimization included investigating variables such as the template structure, type of electrolyte and form of electrolytic deposition. Scanning Electron Microscopy was used to investigate the structures of template matrixes and the resultant materials. The cyclic voltammetry method was applied for the analysis of electrochemical properties and hydrogen evaluation reaction of nano- and microstructured nickel based electrodes. The activity of composite nano- and microstructured materials in various configurations resulting from pore filling of template matrices by nickel was explored. Studies of the physical structure and chemical properties of the nanostructured materials included investigating the necessary parameters of template matrices. The optimum conditions of synthesis, which allowed development of materials with the highest catalytic activity, were determined.
The effect of the template structure on microcrystallinity of the catalyst particles was established using the XRD method. Different new types of non-commercial asymmetric ion track membranes has been tested for nanostructure preparation. The catalytic activity of the new developed nanomaterials is higher as compared to materials using commercial templates. The procedures to modify the newly developed nickel catalyst with Pt, Pd and Pt-Pd alloy have been developed. The Pt and Pt-Pd alloy containing catalyst showed the best performance in water electrolysis. In this work, the promising role for specific application of the new materials in hydrogen economy has been demonstrated.