Thèses sur le sujet « Aggregati stabili »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleures thèses pour votre recherche sur le sujet « Aggregati stabili ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les thèses sur diverses disciplines et organisez correctement votre bibliographie.
Jia, Zichen. « Stability, aggregation kinetics and aggregates thermal restructuring of polymer colloids / ». Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16913.
Texte intégralJohnsson, Markus. « Sterically stabilised liposomes and related lipid aggregates : fundamental studies on aggregate structure and stability / ». Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5027-X/.
Texte intégralHammond, Christian B. « Real Time Investigations of Aggregation of Sulfur-Rich Asphaltene ». Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1587405713284981.
Texte intégralLang, Lisa. « SOD1 Aggregation : Relevance of thermodynamic stability ». Doctoral thesis, Stockholms universitet, Institutionen för biokemi och biofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-139943.
Texte intégralApplewhite, James Kenneth. « Aggregate stability, infiltration, and glomalin in eroded and compacted soils on Fort Hood Military Reservation ». Texas A&M University, 2008. http://hdl.handle.net/1969.1/86062.
Texte intégralKoch, Tyree J. « Aggregation Propensity : Characterization of Monoclonal Antibody Stability ». Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:24078351.
Texte intégralTucker, E. Shannon. « Instability within stability : Conflicting trends beneath Canada's aggregate incarceration rate ». Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28196.
Texte intégralSluzky, Victoria. « Insulin stability and aggregation in agitated aqueous solutions ». Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/36923.
Texte intégralMolope, Mishack Bochankge. « Some effects of biological and physical processess on soil aggregate stability ». Thesis, University of Stirling, 1985. http://hdl.handle.net/1893/2595.
Texte intégralMiyashita, Satoru, Yukio Saito et Makio Uwaha. « Fractal Aggregation Growth and the Surrounding Diffusion Field ». Elsevier, 2005. http://hdl.handle.net/2237/7318.
Texte intégralBlackman, Jonathan David. « Variation and change in the aggregate stability and erodibility of downland soils ». Thesis, University of Sussex, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580147.
Texte intégralLamagna, Sarah Frances. « Development of health indicators for rough fescue grasslands in the southern interior of British Columbia ». Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/4129.
Texte intégralCastillo, Cano Virginia. « Using Small Globular Proteins to Study Folding Stability and Aggregation ». Doctoral thesis, Universitat Autònoma de Barcelona, 2012. http://hdl.handle.net/10803/107824.
Texte intégralThe purpose of the thesis entitled “Using small globular proteins to study folding stability and aggregation” is to contribute to understand how globular proteins fold into their native, functional structures or, alternatively, misfold and aggregate into toxic assemblies. Protein misfolding diseases include an important number of human disorders such as Parkinson’s and Alzheimer’s disease, which are related to conformational changes from soluble non‐toxic to aggregated toxic species. Moreover, the over‐expression of recombinant proteins usually leads to the accumulation of protein aggregates, being a major bottleneck in several biotechnological processes. Hence, the development of strategies to diminish or avoid these aberrant reactions has become an important issue in both biomedical and biotechnological industries. In the present thesis we have used a battery of biophysical and computational techniques to analyze the folding, conformational stability and aggregation propensity of several globular proteins. The combination of experimental (in vivo and in vitro) and bioinformatic approaches has provided insights into the intrinsic and structural properties, including the presence of disulfide bonds and the quaternary structure, that modulate these processes under physiological conditions. Overall, the data illustrates how the establishment of native‐like contacts providing folding intermediates, native structures or protein interfaces with significant thermodynamic stability is a crucial process both to drive protein folding and to compete toxic aggregation.
Liang, Yun [Verfasser]. « Emerging threats to the stability of soil aggregates / Yun Liang ». Berlin : Freie Universität Berlin, 2021. http://d-nb.info/1234451573/34.
Texte intégralRushton, Andrew G. « The effect of flow conditions on the stability of flocs ». Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/27194.
Texte intégralRogers, Stephen Lloyd. « The effect of phototrophic microbial inoculants on soil aggregate stability and soil fertility ». Thesis, University of Kent, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305060.
Texte intégralDrahos, Karen Elizabeth. « Sulfatides mediate Disabled-2 membrane localization and stability during platelet aggregation ». Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/31626.
Texte intégralMaster of Science
Abu-Sen, Laila. « Environmental stability studies of an organic semiconductor ». Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/environmental-stability-studies-of-an-organic-semiconductor(283b640d-b373-4c2d-bfeb-68d7bcae21d4).html.
Texte intégralGeeves, Guy William, et not available. « Aggregate Breakdown and Soil Surface Sealing under Rainfall ». The Australian National University, 1997. http://thesis.anu.edu.au./public/adt-ANU20010702.142014.
Texte intégralTilligkeit, Jacqueline Elizabeth. « The Spatial Distribution of K-Factor Values Across a Toposequence and a Soil Survey Map Unit ». DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/826.
Texte intégralKittner, Madeleine. « Folding and aggregation of amyloid peptides ». Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5357/.
Texte intégralDie Aggregation des Amyloid β (Aβ) Peptids zu Amyloidfibrillen wird mit dem Ausbruch der Alzheimer Krankheit in Verbindung gebracht. Die toxische Wirkung auf Zellen wird vor allem den zeitigen Intermediaten in Form von löslichen Oligomeren zugeschrieben. Aufgrund deren ungeordneter und flüchtiger Natur kann die molekulare Struktur solcher zeitigen Oligomere oft experimentell nicht aufgelöst werden. In der vorliegenden Arbeit wurden aufwendige atomistische Replica-Exchange-Molekulardynamik-Simulationen durchgeführt, um die molekulare Struktur von Monomeren und Oligomeren der Fragmente Aβ(25-35) und Aβ(10-35)-NH2 in Wasser zu untersuchen. Die Faltung und Aggregation von Aβ(25-35) wurde bei neutralem pH und 293 K untersucht. Monomere dieses Fragments bilden hauptsächlich β-Haarnadelkonformationen im Gleichgewicht mit Knäulstrukturen. Innerhalb der β-Haarnadelkonformationen bilden die Residuen G29 und A30 einen β-turn, während N27–K28 and I31–I32 ein β-Faltblatt bilden. Diese β-Haarnadelkonformationen bildeten den Ausgangspunkt zur Modellierung spontaner Aggregation. Wie zu erwarten, bilden sich eine Vielzahl verschiedener, gering besetzter Dimer- und Trimerkonformationen. Mit Hilfe einer gröberen Einteilung können diese in ungeordnete und fibrillähnliche Oligomere unterteilt werden. Ungeordnete Oligomere bilden kompakte Strukturen, die nur durch wenige intermolekulare Wasserstoffbrückenbindungen (HBB) stabilisiert sind. Typisch für fibrillähnliche Oligomere ist hingegen die Ausbildung großer intermolekularer β-Faltblätter. In vielen dieser Oligomere finden wir antiparallele, in- oder out-of-register β-Faltblätter gebildet durch vollständig ausgestreckte Peptide. Ein kleiner Teil der fibrillähnlichen Trimere bildet parallele, V-förmige β-Faltblätter. Die Ausdehnungen ausgestreckter und V-förmiger Oligomere entspricht in etwa den Durchmessern von zwei verschiedenen, experimentell gefundenen Fibrillmorphologien für Aβ(25-35). Die Umwandlung von ungeordneten zu fibrillähnlichen Aβ(25-35) Dimeren ist energetisch begünstigt, läuft aber nicht freiwillig ab. Fibrillähnliche Dimere haben eine geringere Energie aufgrund günstiger Peptidwechselwirkungen (HBB, Salzbrücken), welche durch den Verlust an Entropie kompensiert wird. Etwa 25 % entsprechen dem Verlust an Konfigurationsentropie. Der restliche Anteil wird einem Verlust an Lösungsmittelentropie aufgrund von hydrophoben und elektrostatischen Effekten zugesprochen. Im Gegensatz zur Umwandlung in fibrillähnliche Dimere, ist die Assoziation von Monomeren oder Oligomeren entropisch begünstigt. Beim Vergleich thermodynamischer Eigenschaften der Monomer-, Dimer- und Trimersysteme zeigt sich im Verlauf der Aggregation, wie erwartet, eine Abnahme der Konfigurationsentropie. Zusätzlich nimmt die dem Lösungsmittel zugängliche Oberfläche (SASA), insbesondere die hydrophobe SASA, ab. In Verbindung damit beobachten wir eine Abnahme der freien Solvatisierungsenergie, welche den Verlust an Konfigurationsentropie kompensiert. Mit anderen Worten, der hydrophobe Effekt in Kombination mit elektrostatischen Wechselwirkungen führt zu einem Ansteigen der Lösungsmittelentropie und begünstigt damit die Aggegation. Die spontane Faltung des Aβ(10-35)-NH2 Monomers wurde für zwei verschiedene Proteinkraftfelder, GROMOS96 43a1 und OPLS/AA, untersucht und mit primären NMR-Daten aus der Literatur, gemessen bei pH 5.6 und 283 K, verglichen. Beide Kraftfelder generieren unterschiedliche Hauptkonformationen. Der Vergleich zwischen experimentellen und berechneten Kern-Overhauser-Effekt (NOE) Abständen ist nicht ausreichend, um zwischen beiden Kraftfeldern zu unterscheiden. Der Vergleich mit Kopplungskonstanten aus Experiment und Simulation zeigt, dass beide Simulationen einem pH-Wert geringer als 5.6 ensprechen. Basierend auf den bisherigen Ergebnissen können wir nicht entscheiden, welches Kraftfeld eine bessere Beschreibung für dieses System liefert. Die Dimerisierung von Aβ(10-35)-NH2 wurde bei neutralem pH und 300 K untersucht. Wir finden eine Vielzahl verschiedener, gering besetzter Dimerstrukturen, welche eher durch Seitenkettenkontakte als durch spezifische HBB stabilisiert sind. Wie bei den Aβ(25-35) Dimeren, ist die Umwandlung zu β-Faltblattreichen, fibrillähnlichen Aβ(10-35) Dimeren energetisch begünstigt, konkurriert aber mit einem Entropieverlust. Die Umwandlung wird in diesem Fall durch elektrostatische Wechselwirkungen zwischen Peptid und Lösungsmittel und innerhalb des Lösungsmittels bestimmt.
Dorji, Tshering. « Soil organic carbon variability under montane ecosystems : assessing the influence of landscape attributes ». Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14811.
Texte intégralSALA, BENEDETTA MARIA. « DISSECTING STRUCTURAL ASPECTS OF PROTEIN STABILITY ». Doctoral thesis, Università degli Studi di Milano, 2018. http://hdl.handle.net/2434/570253.
Texte intégralRebodos, Robert Louie Fermo. « Implications of Oxidation on the Colloidal Stability of Magnetite Nanoparticles and Cluster ». Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77117.
Texte intégralPh. D.
DeLong, George T. (George Thomas). « Solution Studies of the Structures and Stability of Mixed Lithium Alkoxide/Alkvllithium Aggregates ». Thesis, University of North Texas, 1992. https://digital.library.unt.edu/ark:/67531/metadc279031/.
Texte intégralSifniotis, Vicki. « Towards The Development of Biobetter Therapeutic Whole Antibodies ». Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20829.
Texte intégralAdams, Kimberly Ellen. « Influence of Vineyard Floor Management Practices on Soil Aggregate Stability, Total Soil Carbon and Grapevine Yield ». DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/612.
Texte intégralChevallier, Marie. « Stabilisation des émulsions laitières aux cours des traitements technologiques : action combinée des agrégats de protéines de lactosérum et des caséines ». Thesis, Rennes, Agrocampus Ouest, 2017. http://www.theses.fr/2017NSARB294/document.
Texte intégralDairy emulsions are thermodynamically unstable systems, which have to be resistant to the technological treatments (heating, freezing/thawing) applied during their manufacture or use. Whey protein-rich emulsions are particularly sensitive to technological treatments and instabilities are currently tackled by the use of non-dairy additives. With aim to offer products that are more natural to consumers (additive-free), the preparation of whey protein-rich emulsions without additive and stable during technological treatments constitutes a major challenge for dairy companies. The strategy adopted during this thesis was to combine the properties of the whey proteins aggregates and caseins in order to stabilize emulsion during technological treatments in a large range of protein concentrationsEmulsions were prepared with various whey protein aggregates and various whey protein aggregates/caseins ratio. Whatever the whey protein aggregates, their presence at the fat droplet surface destabilize the emulsions (gelation/phase separation) whereas they are stable in the continuous phase of the emulsions during technological treatments. In contrast, emulsions are extremely stable during technological treatments when caseins fully cover the fat droplet surface. The results obtained highlighted the possibility of modulating the stability during technological treatments of whey protein-rich emulsions by combining the properties of the whey protein aggregates and the caseins and by controlling their repartition between the fat droplet surface and the continuous phase of the emulsion
Johnsson, Markus. « Sterically stabilised liposomes and related lipid aggregates : Fundamental studies on aggragate structure and stability ». Doctoral thesis, Uppsala University, Department of Physical Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-663.
Texte intégralVarious aspects of and approaches towards the steric stabilisation of liposomes have been investigated, mainly by use of fluorescence techniques and cryo-transmission electron microscopy (cryo-TEM). It is shown that PEG(2000)-lipids can be incorporated in the liposome membrane up to a critical concentration of 8-10 mol% without any observable structural perturbations. Above 10 mol%, a breakdown of the liposome structure into flat lamellar discs was observed. The sterically stabilised liposomes displayed similar, or even reduced, membrane permeability as compared with conventional liposomes. The presence of PEG-lipids in the EPC membrane was shown to affect the liposome-to-micelle transition in mixtures containing OG. Little or no effects of the PEG-lipids were found on the transition in mixtures containing C12E8.
The interactions between a number of PEO-PPO-PEO triblock copolymers and PC or PC/Chol liposomes have been investigated. It is shown that these polymers adsorb rapidly onto the liposome surface and induce a substantial increase in membrane permeability as well as structural perturbations. No evidence of an effective steric stabilisation due to the presence of the polymers at the membrane surface was found. This was shown, by the use of a QCM-technique, to be a consequence of the weak interaction between the polymers and the lipid membrane.
Dispersions of reversed lipid phases in mixtures of DOPE and PEG-lipids were characterised using cryo-TEM. Dispersions displaying reasonable colloidal stability were obtained and particles exhibiting a periodic dense inner structure were observed.
PEG-lipid micelles were characterised mainly using light scattering techniques. Micelle aggregation numbers and hydrodynamic radii were determined as a function of temperature. It is shown that the inter-micellar interactions are dominated by the steric repulsion.
PEG-lipid stabilised liposomes loaded with boronated drugs intended for BNCT have been characterised. The drugs were efficiently encapsulated into the liposomes, resulting in a drug precipitation in the water core of the liposomes.
Pothier, Laura J. « Effects of amino acid substitutions on the conformation and stability of A[beta]₁₆₋₂₂ aggregates / ». Connect to online version, 2007. http://ada.mtholyoke.edu/setr/websrc/pdfs/www/2007/213.pdf.
Texte intégralPeduzzo, Alessia [Verfasser]. « Mechanistic insights into α-synuclein aggregation : from fibril stability to surface nucleation / Alessia Peduzzo ». Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2019. http://d-nb.info/1201881978/34.
Texte intégralHerman, David Joel. « Stabilization of weakly charged microparticles using highly charged nanoparticles ». Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/34345.
Texte intégralMaster of Science
Flaugh, Shannon L. « Folding, stability and aggregation of the long-lived eye lens protein human gamma D crystallin ». Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/34572.
Texte intégralVita.
Includes bibliographical references (p. 179-194).
Human [gamma]D crystallin (H[gamma]D-Crys) is a monomeric, two domain, primarily P-sheet protein found in high concentrations in the human eye lens. H[gamma]D-Crys and other crystallins are found in insoluble protein inclusions associated with the eye disease cataract. H[gamma]D-Crys is expressed in utero and does not regenerate during life, thus necessitating high stability and solubility. Covalent damage, including glutamine deamidation, of the lens crystallins increases with age and as a result of exposure to environmental insults. Such covalent damage may cause partial-unfolding into aggregation-prone confomations that cause cataract. The in vitro stability of H[gamma]D-Crys was analyzed in the denaturant guanidine h[gamma]Drochloride at pH 7.0 and 370C. An off-pathway aggregation reaction that competed with refolding was previously reported when H[gamma]D-Crys was refolded to less than 1 M GuHC1. Equilibrium transitions of H[gamma]D-Crys were best fit to a three-state model suggesting the presence of a partially-folded intermediate that likely had a structured C-terminal domain (C-td) and unstructured N-terminal domain (N-td). Similarly, previous analyses revealed a sequential domain refolding pathway where the C-td refolds first followed by the N-td.
(cont.) These findings suggest that the inter-domain interface of H[gamma]D-Crys is important in both folding and stability. The domain interface of H[gamma]D-Crys contains a central h[gamma]Drophobic cluster of six residues and two pairs of peripheral interacting residues. To test this importance of these residues in folding and stability, site-directed alanine mutants were constructed at all ten positions and properties of the mutant proteins were analyzed. Single mutations of h[gamma]Drophobic domain interface residues caused a decrease in stability of the N-td, but did not affect stability of the C-td. Similarly, stability of the N-td but not the C-td was reduced as a result of single and double mutations of peripheral interface residues. Minimal to no interaction energy was observed for the peripheral residues suggesting they contribute to stability indirectly, perhaps by shielding the central h[gamma]Drophobic cluster from solvent. Both the h[gamma]Drophobic and peripheral domain interface alanine mutants also had reduced rates of productive refolding for the N-td while refolding rates for the C-td were unchanged. These results suggest a productive folding pathway where the C-td refolds first and domain interface residues of the structured C-td act as a nucleating center for refolding of the N-td.
(cont.) Effects on N-td refolding rates were most prominent for the h[gamma]Drophobic residues indicating the importance of proper h[gamma]Drophobic burial during refolding. The peripheral domain interface residues of H[gamma]D-Crys include a pair of two glutamines that are targets for covalent damage during aging. Deamidation mimics at these sites were constructed by site directed mutagenesis of glutamine to glutamate. Properties of the mutants were analyzed to assess the affects of deamidation on stability and folding. Similar to the alanine mutants at these sites, the deamidation mutants had a destabilized N-td but not C-td at pH 7.0. In contrast, stabilities of the mutants were indistinguishable from wild type at pH 3.0. The N-td of the deamidation mutants also unfolded faster than that of wild type during kinetic unfolding. These results indicate that deamidation of domain interface glutamines destabilizes H[gamma]D-Crys and lowers the kinetic barrier to unfolding. A reduction in the thermodynamic and kinetic stability as a result of domain interface deamidation could result in the population of partially-unfolded conformations in the lens that may aggregate through mechanisms such as domain swapping or loop-sheet insertion.
by Shannon L. Flaugh.
Ph.D.
Mills-Henry, Ishara Amenti Rakem. « Stability, unfolding, and aggregation of the gamma D and gamma S human eye lens crystallins ». Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/38627.
Texte intégralIncludes bibliographical references (v. 2, leaves 189-208).
The transparency of the human eye lens depends on the properties of the a- crystallin and py-crystallin families of proteins, which accumulate to very high concentrations in mature lens fiber cells. The 0- and y-crystallins are thought to be primarily structural proteins while a-crystallin possess an additional chaperone activity. Aggregation of partially unfolded or covalently damaged forms of these proteins results in cataract, which is the leading cause of blindness in the world. The biochemical basis of the very high crystallin stability, and the nature of the misfolded, modified, or aggregated states, are thus of considerable importance in understanding the etiology of loss of lens transparency. All vertebrate P- and y-crystallins are homologous and contain two highly symmetrical domains with a hydrophobic interface connected by an interdomain linker. The overall sequences, fold topology, and domain interfaces of vertebrate py-crystallins are highly conserved. The two domain 0- and y-crystallins are believed to have evolved by gene duplication and fusion from an ancestral single domain py-crystallin. This thesis is focused on stability and aggregation properties of human yD crystallin (yDwT) and human yS crystallin (ySwT), two of the most abundant proteins in the human lens.
(cont.) Terminally differentiated fiber cells in the central nucleus of the lens are enucleated and devoid of organelles. The yD crystallins synthesized in utero must remain stable and soluble throughout life. The yS protein is more prevalent in the cortical regions of the lens, where protein degradation and synthesis do occur. Given the importance of long-term solubility for the crystallins, it seems likely that selection for the two-domain form is related to the need for very long-term stability. Comparison of the stabilities of the isolated domains and the intact protein indicated that the domain interface contributes a AGH20 of~ 4.2 kcal*mol-l to the stability of the complete yDwT two-domain protein. The differential stability observed for the yD isolated domains was not as distinct for the yS isolated domains. These results support the idea that selection for increased thermal stability was one of the factors leading to the evolution of two domain crystallins. A distinct hysteresis occurs during equilibrium unfolding and refolding, due to a kinetic barrier in the unfolding pathway. By extrapolating kinetic unfolding results from denaturing GuHCl concentrations to buffer, I show that the ti2 for the initial unfolding step is -19 years. The value extrapolated for the YSwT is not as long, though still significant. This supports the earlier conclusion that the domain interface is an important source of stability.
(cont.) Previous studies had shown that upon dilution from denaturant partially folded intermediates of yD crystallin formed highly ordered fibrous aggregates that were not amyloid in nature. This aggregation reaction of yDwT polypeptide chains competing with productive refolding provided a model for cataractogenesis in vitro. The structurally homologous ySwT crystallin did not exhibit an off-pathway aggregation under the same conditions as yDwT. This suggested that the pathway of aggregation involved specific amino acids or sequences essential for association and was not a general feature of the y- crystallins. To investigate this disparity between two structurally similar crystallins, chimera proteins were created in an attempt to narrow down regions of the protein that promoted aggregation in DwTr or regions in ySwT that inhibited aggregation. The aggregation behavior upon refolding was analyzed for the chimeras and isolated single domains. Partitioning of refolding chains into the aggregation pathway was strongest for the full-length proteins that retained the yD interface. This result is consistent with a domain swapping mechanism for the off-pathway aggregation of the crystallins. This aggregation reaction may be coupled to the increased stability of the yD-protein, as a kind of evolutionary cost of the extremely stable and long-lived native state conformation.
by Ishara Amenti Rakem Mills-Henry.
Ph.D.
Krchnák, Martin. « Sestava ocelových zásobníků kameniva ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240079.
Texte intégralGhiafeh, Davoodi Majid. « Long term stability of concrete made from red sand in a marine environment ». Thesis, Curtin University, 2008. http://hdl.handle.net/20.500.11937/1108.
Texte intégralLarišová, Lucie. « Vliv vodní eroze na vybrané fyzikální vlastnosti půdy ». Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-392276.
Texte intégralMetzman, Jonathan Seth. « Nanoparticle Encapsulation and Aggregation Control in Anti-reflection Coatings and Organic Photovoltaics ». Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85580.
Texte intégralPh. D.
Investigations are presented on the quality of distribution or dispersion of functional inorganic (composed of silicon dioxide or silver) particles that have dimensions of less than 100 nanometers, called nanoparticles. The nanoparticle surfaces were covered with polymer layers, where polymers are organic materials with repeating molecular structures. The study of these nanoparticle distribution effects were first examined in anti-reflection coatings (ARCs). ARCs induce transparency of windows or glasses through a reduction in the reflection of light. Here, the ARCs were fabricated as self-assembled thin-films (films with thicknesses ranging from 1 to 2000 nanometers). The self-assembly process here was carried out by immersing a charged substrate (microscope slide) into a solution with an oppositely-charged material. The attraction of the material to the substrate leads to thin-film growth. The process can continue by sequentially immersing the thin-film into oppositely-charged solutions for a desired number of thin-film layers. This technique is called ionic self-assembled multilayers (ISAMs). ARCs created by ISAM with charged polymers (polyelectrolytes) and silicon dioxide nanoparticles (SiO2 NPs) can lead to highly-transparent films, but unfortunately, they lack the stability and scratch-resistance necessary for commercial applications. In this dissertation, we address the lack of stability in the ISAM ARCs by adding additional polyelectrolyte layers that can develop strong, covalent bonds, while also examining nanoparticle dispersive properties. First, SiO2 NP surfaces were coated in solution with a polyelectrolyte called diazo-resin, which can form covalent bonds by UV-light exposure of the film. After tuning the concentration for the added diazo-resin, the coated SiO2 NPs were used to make ARCs ISAM films. The ARCs had excellent nanoparticle dispersion, high levels of transparency, and chemical stability. Chemically stability entails that the integrity of the film was unaffected by exposure to polar organic solvents or strong polyelectrolytes. In a second method, two additional v polyelectrolyte layers were added into the original polyelectrolyte/SiO2 NP design. Here, heating of the film to 200 oC temperatures induced strong covalent bonding between the polyelectrolytes. Variation of the solution pH dramatically changed the polyelectrolyte thickness, the nanoparticle dispersion, the scratch-resistance, and the anti-reflection. An optimum trade-off was discovered at a pH of 5.2, where the anti-reflection was excellent (amount of transmitted light over 99%), along with a substantially improved scratch-resistance. A change of pH from 6.0 (highest tested pH) to 5.2 (optimal) caused a difference in the scratch-resistance by a factor of seven. In these findings, we introduce stability enhancing properties from films composed purely of polyelectrolytes into nanoparticle-containing ISAM films. We also show that a simple adjustment of solution parameters, such as the pH value, can cause substantial differences in the film properties. Nanoparticle dispersion properties were next investigated in organic photovoltaics (OPVs) OPVs use semiconducting polymers to convert sunlight into usable electricity. They have many advantages over traditional solar cells, including their simple processing, low-cost, flexibility, and lightweight. However, OPVs are limited by their total optical absorption or the amount of light that can potentially be converted to electricity. The addition of plasmonic nanoparticles into an OPV device is a suitable way to increase optical absorption without changing the other device properties. Plasmonic nanoparticles, which are composed of noble metals (such as silver or gold), act as “light antennas” that concentrate incoming light and radiate it around the particle. In this dissertation, we investigate the dispersion and stability effects of polymer or metallic layers on silver nanoplates (AgNPs). The stability of the AgNPs was found to be greatly enhanced by coating the nanoparticle edges with a thin gold layer (AuAgNPs). AuAgNPs could then be introduced into a conductive, acidic layer of the OPVs (PEDOT:PSS) to increase the overall light absorption, which otherwise would be impossible with uncoated AgNPs. Next, the AgNPs were distributed on top of the photoactive layer or the layer that is responsible for absorbing light. Coating the AgNPs with a polystyrene polymer layer (PS-AgNPs) allowed for excellent dispersion on this layer and contrastingly, dispersion of the uncoated AgNPs was poor. An increased amount PS-AgNPs added on top of the photoactive layer progressively increased the optical absorption of the OPV devices. However, trends were quite different for the power conversion efficiency or the ratio of electricity power to sunlight power in the OPV device. The greatest PCE enhancements (27 – 32%) were found at a relatively low coverage level (using a solution concentration of 0.29 to 0.57 nM) of the PS-AgNPs on the photoactive layer.
Vahidnia, Arash. « Wide area control through aggregation of power systems ». Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/61186/1/Arash_Vahidnia_Thesis.pdf.
Texte intégralJoshi, Gyawali Ayush. « A fresh soil health perspective : Soil health dynamics and improved measurement techniques ». Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/89949.
Texte intégralDoctor of Philosophy
If we want to make sure that ample and safe food is available to future generations, then it is time that we produce food without damaging the soil. Many widely used soil management techniques like tillage and leaving the field bare can harm the soil and decrease productivity in the long run. One potential technique to produce food while protecting the soil and environment is conservation agriculture, which can include reduced tillage and cover cropping. Reduced tillage is a technique in which we grow food without majorly disturbing the soil, while cover crops are planted when cash crops are not in the field in order to improve or sustain the soil. Understanding the soil-related benefits of conservation agriculture practices is important to encourage farmers to adopt these practices. In this study we tested the effects on soils of reduced tillage and cover crop practices versus conventional tillage and bare soil practices, using five locations across Virginia. We also developed improved methods for measuring two informative soil parameters. We found that, when looking at all of our five sites, the stability of soil aggregates, the rate at which water enters soil, and the nutrients in surface soils were all affected by the type of management that the soils were subjected to. Reduced tillage increased stability of soil aggregates when compared with conventional till. This increased stability of aggregates indicators lower potential for surface water runoff, erosion, and flooding when we practice reduced tillage. Cover cropping also increased stability of soil aggregates, especially when the cover crops attained substantial above-ground mass. Soil nutrients (which are essential for plants to grow) were also overall higher in the surface soil layers under no-till. Since the stability of soil aggregates was found to be an important benefit of CA practices, we also perceived a need for a better method for measuring stability of these aggregates. In response, we developed a new index called Integrated Aggregate Stability (IAS). IAS was found to give similar results as established methods, but the time required to get IAS result is about 10 minutes, whereas the time required for established methods like wet sieving is around 2 days. IAS measurements are therefore both accurate and quick to perform. We also focused on developing an inexpensive tool for measuring soil respiration. Soil respiration-based measurements help us to understand the activity of microbes in the soil. These microbes are very important for soils to function. Our tool, Soil Microbial Activity Assessment Contraption (SMAAC), was very consistent with a currently used tool and shows high potential for future use. Altogether, we found that no-tillage and cover cropping can increase stability of soil aggregates even within 1-3 years of starting those practices. No-till can also increase nutrient concentrations in the top soil layer. The tools and innovations developed in this study have the potential to increase the ability of farmers to assess soil health and also encourage greater adoption of conservation agriculture practices.
Pokhrel, Lok R. « Evaluation of Colloidal Stability and Ecotoxicity of Metal-based Nanoparticles in the Aquatic and Terrestrial Systems ». Digital Commons @ East Tennessee State University, 2013. https://dc.etsu.edu/etd/1132.
Texte intégralForero-Laverde, Germán. « The Impossible Trinity and Financial Stability. The Incidence of Trilemma Regimes on the (In)stability of Stock Markets and Credit Aggregates (1922-2013) ». Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663993.
Texte intégralZhang, Li. « The study of phase separation in the miscibility gap and ion specific effects on the aggregation of soft matter system ». Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS106/document.
Texte intégralPhase separation process is important as it determines the structure of the final materials. There are many systems that have more than one phase such as foams and gels. Aqueous foams are dispersions of gas bubbles in a water phase and gels appear when some basic microscopic unit starts to aggregate forming a large solid network that spans macroscopic space. They have many applications in industry and daily life. In the present thesis, firstly, I focus on studying different types of phase separation. Secondly, I studied the ion specific effects on the aggregation of colloidal particles and surfactant, the purpose is to make stable foams. In the miscibility gap there are two types of phase separation: Nucleation growth and spinodal decomposition, they have different growth mechanisms and kinetics. Therefore, my first p project is to investigate the evolution process of them and their effects to the final structure of material. Gels can be made by adding salt to the dispersion of colloidal particles, they have a large number of applications such as in food and material science. In this dissertation, we use different types of salts to compare gel properties from both macroscopic and microscopic aspects. Obtaining stable foams is significant in the view of their plenty of applications, but the ways to make them are mostly complicated. In this thesis, we can obtain stable foams via two ways. One is simply by adding salts to surfactant solutions, through which we can make ultrastable foam. Another way is using the gel phase we have studied as the continuous phase in foams to arrest the foam aging
Bauer, Horst Hermann. « Physical stability of peptide pharmaceuticals : aggregation and conformational changes of human calcitonin (hCT) in aqueous solution / ». [S.l.] : [s.n.], 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10989.
Texte intégralMolina, Diogenes. « Intelligent control and system aggregation techniques for improving rotor-angle stability of large-scale power systems ». Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50291.
Texte intégralQuadling, Amanda Gail. « The role of aggregates in the thermal stability of Mg-PSZ refractories for vacuum induction melting ». Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/28684.
Texte intégralNciizah, Adornis Dakarai. « Aggregate stability, crust formation, steady state infiltration and mode of seedling emergence in soils with various texture and mineralogy ». Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/d1015539.
Texte intégralCousen, S. M. L. « The assessment of soil aggregate stability to raindrop impact for some tropical soils material, with particular reference to iron ». Thesis, University of Portsmouth, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375487.
Texte intégralLee, Sung Mun. « Role of aggregation conditions and presence of small heat shock proteins on abeta structure, stability and toxicity ». Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/3905.
Texte intégralGhiafeh, Davoodi Majid. « Long term stability of concrete made from red sand in a marine environment ». Curtin University of Technology, School of Engineering, Department of Civil Engineering, 2008. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=115095.
Texte intégralThe comparative analysis between normal mix proportions and the mix proportions utilizing Red Sand was also achieved. In addition, the impact of marine environment on concrete mix design and properties of manufactured concrete were evaluated with a series of standard laboratory tests. The findings were promising in terms of both mechanical properties and durability and suggested that Red Sand, in particular Low Iron Sand is likely to be effective in place of fine aggregates and can be used within marine grade concrete with no major differences when compared to normal concrete. From the results obtained, it can be deduced that this material can be used in a wide range of concrete applications in Civil Engineering and Construction.