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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis and Characterization of Functionalized Bio-Molecular Surfaces with Self-Assembled Monolayers and Bioreactive Ligands for Nano/Biotechnological Applications

Wang, Lian January 2008 (has links)
In this work, the synthesis and characterization of functionalized biosurfaces that can be used for bioseparations and bio-nanotechnology are reported. A novel protein purification technique that incorporates chelating ligands and polymers onto the same chromatographic matrix is explored. A polysaccharide based gel, agarose, was modified systematically with hybrid ligands of the chelator iminodiacetic acid (IDA) and the polymer polyethylene glycol (PEG). The PEG molecule acts as a blocking polymer that can allow only small proteins to permeate onto the matrix surfaces and form conventional immobilized metal ion affinity chromatographic (IMAC) interactions with the chelators. Kinetic studies of chelator and polymer attachment were performed in order to effectively control the chelator and polymer densities on the matrix. Studies with different PEG surface densities and their effects on the adsorption of several proteins (e.g. myoglobin, lysozyme and bovine serum albumin (BSA)) were evaluated to characterize these new hybrid size exclusion IMAC (SEIMAC) matrices. An exclusion effect was observed while adsorption as observed in IMAC systems took place.Functionalization schemes and procedures were extended in the activation and incorporation of affinity ligands on inorganic surfaces such as gold surfaces. Functional gold platforms were explored for development of nano-interconnects via functionalized self assembled monolayers (FSAMs) on gold to attach specific affinity ligands as linkers to immobilize biomolecules, such as microtubules (MTs). MTs eventually could be utilized as self assembling structures and templates for fabrication of nano-scale bio-interconnect arrays and networks. In this work, different organothiols were used to form FSAMs and anti-glutathione S-transferase was attached as a linker to utilize the attachment of MT cap proteins, gamma-tubulin. The gamma-tubulin could recognize specifically a heterodimer of the MTs and can provide a nucleation center for MT growth. Several methodologies were employed including photolithographic methods and the use of photoreactive compounds for proper micro/nano scale dual protein functionalization of surfaces with homogeneous affinity ligands and with heterogeneous ligands as well.
2

Catalysis and materials development for photolithography

Mesch, Ryan Alan 11 September 2015 (has links)
In recent years the microelectronics industry as found itself at an impasse. The tradition pathway towards smaller transistors at lower costs has hit a roadblock with the failure of 157 nm lithography and the continued delays in 13.5 nm extreme ultra violet light sources. While photolithography has been able to keep pace with Moore’s law over the past four decades, alternative patterning technologies are now required to keep up with market demand. The first section of this dissertation discusses the new resolution enhancement technique develop in the Willson lab termed pitchdivision. Through the incorporation of specifically tailored photobase generators (PBGs) into commercially available resists, the resolution of current 193 tools may be doubled. Special two-stage PBGs were designed and synthesized to increase the image fidelity of pitchdivision patterns. The next project deals with the design, synthesis, and evaluation of resists that find amplification through unzipping polymers. An aromatizing polyester polymer that acts as dissolution inhibitor in novolac and is inherently sensitive to 13.5 nm exposure is discussed. Initial results show excellent sensitivity and promise towards a new class of EUV resists. / text
3

Phasenübergänge und Photoreaktionen in Polyelektrolyt-Tensid-Komplexen

Frömmel, Jens 25 September 2019 (has links)
Verändern Photoreaktionen eingelagerter Substanzen die Klärtemperatur flüssigkristalliner Polyelektrolyt-Tensid-Komplexe? Komplexe (Salze) aus Polyaminen und Alkylsulfonsäuren bilden mit Wasser einen hexagonalen Flüssigkristall, der sich beim Erwärmen in eine optisch isotrope Phase umwandelt. In diese Demethylionenalkylsulfonate genannten Komplexe werden Bisthienylcyclopentene mit Alkylsulfonatseitenketten zwar ortsfest eingelagert, deren Photozyklisierung verschiebt das Gleichgewicht jedoch nur wenig von der hexagonalen zur isotropen Phase. Hingegen verläuft die Photozyklisierung der Bisthienylcyclopentene im festen Komplex teilweise deutlich langsamer als in Lösungen. / Can photoreactions of embedded substances change phase transition temperatures of polyelectrolyte surfactant complexes? Complexes made from polyamines and alkyl sulfonates form an hexagonal liquid crystal in presence of water, which is converted to optical isotropic phase by heating. These complexes resembling those of ionenes are called demethyl-ionene alkyl sulfonates. Bisthienylcyclopentenes bearing alkyl sulfonate side chains are incorporated into these complexes and keep their locations over prolonged periods of time, but the photocyclization of the chromophore only slightly shifts the equilibrium from hexagonal liquid crystal towards the optical isotropic phase. Conversely, the photocyclization of bisthienylcyclopentenes partially proceeds appreciably slower within the solid complex than in solution.
4

Modelling and elucidation of photoreaction kinetics : applications and actinometry using nifedipine, nisoldipine, montelukast, fluvoxamine and riboflavin

Maafi, Wassila January 2016 (has links)
The kinetics of drugs photodegradation have traditionally been treated using thermal kinetic analysis methods consisting most commonly in zero and first order kinetics. These treatment strategies were shown to lack specificity and present a number of limitations when applied to photoreactions kinetics. Nevertheless, these methods have widely been used due to a lack of integrated rate-laws for the majority of photoreactions types, in turn, due to the presence of a variable time-dependent factor in most photoreactions rate-laws that prevents their mathematical integration. To address these limitations, a new methodology for the development and validation of semi-empirical integrated rate-laws that faithfully describe photoreactions kinetics and photoreactions simulated cases generated by numerical integration methods (NIMs), is hereby presented. Using this methodology, a new kinetic order was ascribed to photoreactions namely the Φ-order kinetics. Semi-empirical integrated rate-laws were, thus, developed for three photoreaction types namely, unimolecular, AB(1Φ), photoreversible ,AB(2Φ), and consecutive, AB4(4Φ), photoreactions. The proposed models were further tested experimentally on drugs following these photodegradation mechanisms using; nifedipine and nisoldipine for unimolecular photoreactions; montelukast and fluvoxamine for photoreversible reactions; and riboflavin for consecutive photoreactions. The developed models not only accurately described the photoreaction kinetics of these drugs but also allowed the determination of all the kinetic parameters that characterise them. Furthermore, the above studied drugs were shown to act as precise and simple actinometers when analytically treated with the Φ-order kinetic methods, hereby presented. A universal standard method for the precise and worldwide reproducible study of drugs stability and compounds photoreactions, based on monochromatic irradiation and Φ-kinetics data analysis, is also detailed and adopted throughout the thesis. Finally, two new kinetic parameters namely, the pseudo-rate-constant and pseudo-initial velocity have been identified and shown to be more reliable and accurate in the description and universal comparison of photoreactions kinetics.

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