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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.
21

Investigation Of Electromigration And Stress Induced Surface Dynamics On The Interconnect By Computer Simulation

Celik, Aytac 01 March 2011 (has links) (PDF)
Purpose of this work is to provide a comprehensive picture of thin film (interconnect) and solid droplet surface evolution under the several external applied forces with anisotropic physical properties so that one can eventually be able to predict main reasons and conditions under which stability of surface is defined. A systematic study based on the self-consistent dynamical simulations is presented for the spontaneous surface evolution of an thin film and isolated thin solid droplet on a rigid substrate, which is driven by the surface drift diffusion induced by the anisotropic diffusivity, the anisotropic capillary forces (surface stiffness) and mismatch stresses under electron winding. The effect of surface free energy anisotropies (weak and strong (anomalous)) on the development kinetics of the Stranski-Krastanow island type morphology are studied. Although, various tilt angles and anisotropy constants were considered during simulations, the main emphasis was given on the effect of rotational symmetries associated with the surface Helmholtz free energy topography in 2D space. The investigations of dynamics of surface roughness on concurrent actions of the appliedelasto- and electro- static fields clearly indicate that applied misfit stress level is highly important effect on resultant surface form which may be smooth wave like or crack like. The droplet simulations revealed the formation of an extremely thin wetting layer during the development of the bell-shaped Stranski-Krastanow island through the mass accumulation at the central region of the droplet via surface drift-diffusion. The developments in the peak height, in the extension of in the wetting layer beyond the domain boundaries, and the change in triple junction contact angle, one clearly observes that these quantities are reaching certain saturation limits or plateaus, when the growth mode turned-off. Islanding differences for weak anisotropy constant levels and the strong (anomalous) anisotropy constant domains are discussed.
22

Application Of The Map Correlation Method To The Western Blacksea Basin

Ergen, Mehmet Kayra 01 June 2012 (has links) (PDF)
Turkey is a developing country and its energy demand is increasing due to its growing population and industry. As a result, to fulfill this growing energy demand, Turkey is currently developing its unused hydropower potential, especially through small hydroelectric power plants (SHPPs). Estimation of annual electricity generation of a small hydropower plant strongly depends on streamflow data. In Turkey, there are a limited number of streamgaging stations so the estimation of streamflow at a potential SHPP location requires transferring streamflow time series from a reference streamgaging station to the ungaged basin. In order to determine daily streamflow time series for ungaged catchments, typically the nearest streamgaging station is chosen as the reference streamgaging station. However the distance between a reference streamgaging station and an ungaged catchment may not always be the most appropriate reference streamgaging station selection criterion. Archfield and Vogel (2010) proposed a new method called the Map Correlation Method (MCM) to select a reference streamgaging station to donate its observations to an ungaged catchment. MCM aims to identify the most correlated streamgaging station with the ungaged catchment. This new method is used at the Western Blacksea Basin in Turkey to select the best among possible reference streamgaging stations. The method proved to be promising / the most correlated streamgaging station for approximately one third of the study streamgaging stations are identified correctly by the MCM.
23

Entscheidungsproblem Unternehmen - Standort / Decision problem company - location : Comparing normative, behavioural and structural location analysis approaches

Eisold, Hans-Elmar 19 May 2014 (has links) (PDF)
Die Standortnotwendigkeit ist Problem und Chance für Unternehmen (Standortsuche) und Standorte (Standortmarketing) gleichermaßen. Unternehmen sind dabei dem Einfluss durch die Gewichtung von Shareholder- und/oder Stakeholderinteressen unterworfen und der Wirkung harter wie weicher Standortfaktoren ausgesetzt. Die klassische Standortlehre allein stellt dabei nur einen unzureichenden Handlungsablauf dar. Ihr gegenüber ist die Annahme eines Standortfaktorenmix mit objektiven wie subjektiven Kriterien sinnvoller. Die Standortanalyse klassischer Ansätze kann durch verhaltens- und strukturorientierte Vorgehensweisen sinnvoll erweitert werden, um dem Situationsgemenge aus ökonomischem Ziel, unternehmerischer Situation und subjetiver Standortentscheidung besser gerecht zu werden. Die Annahme vollständiger Produktionsverlagerung weicht der Verlagerung einzelner Wertschöpfungsstufen innerhalb einer Wertschöpfungskette. Ein vernünftiger Analyse- und Entscheidungprozess muss daher ganzheitlicher erfolgen und führt dann zu besser abgesicherten Antworten auf die Fragen nach dem "was" wird "weshalb" notwendigerweise "wohin" verlagert.
24

Kinetics Of Methyl Lactate Formation Over The Ion Exchange Resin Catalysts

Akbelen Ozen, Serap 01 April 2004 (has links) (PDF)
iv The recovery of lactic acid from its dilute aqueous solutions is a major problem. The ester of lactic acid, namely, methyl lactate has a wide range of applications. The esterification of an aqueous solution of lactic acid with methanol is a reversible reaction. As excess of amount water is present in the reaction mixture, the conversion is greatly restricted by the chemical reaction equilibrium limitations. In this study the esterification kinetics of lactic acid with methanol both in the absence and presence of an ion exchange resin as a heterogeneous acid catalyst was investigated with isothermal batch experiments between 40 - 70 0 C and at atmospheric pressure. Self-polymerization of lactic acid was enlightened by considering the hydrolysis reaction of lactoyllactic acid at the reaction temperatures and at various initial concentrations. Both homogeneous and heterogeneous reaction rate constants were evaluated. Methyl lactate process development was also investigated. The process was based on the recovery of 10% lactic acid by reaction with methanol in a absorption column using ion-exchange resin Lewatit SPC-112 H+. The effect of various parameters including lactic acid concentration or reactant molar ratio, lactic acid feed flow rate, methanol and inert carrier rate on reactor performance were studied. The reaction of methyl lactate formation over the ion exchange resin catalyst was observed to be slower than the mass transfer rate whereas mass transfer of methanol in gas phase was the limiting step for methanol transfer to the liquid mixture. Mass transfer of water from liquid phase to the gas phase was controlled by the mass transfer resistance of liquid phase. Thus, it can be concluded that the counter-current gas-liquid reactors with acidic solid catalysts can be used as simultaneous reaction and separation equipment.
25

Determination Of Contact Angles Of Powders By Capillaric Dewatering Of Filter Cakes

Eratak, Deniz Ozlem 01 January 2005 (has links) (PDF)
Solid-liquid contact angle is an important parameter in many particulate processes of the mineral, ceramic and chemical industries. In particular, modification of the contact angle through surface active agents plays a crucial role in froth flotation of minerals. In the case of flat solid surfaces, direct measurement of the contact angle is possible. However, such flat surfaces can not be obtained with finely divided solids typically encountered in flotation applications. Then, indirect methods based on powder beds as thin layers of powders deposited on glass plates or packed columns are used for the determination of apparent contact angles. This thesis presents an alternative novel method based on the capillaric dewatering of filter cakes for the measurement of the receding contact angle and correlates the contact angles measured as such with column wicking and micro-flotation test results of zircon and rutile mineral particles. The experimental procedure is simple and fast. The results have proven that the proposed method is reliable and give a good measure of the contact angle in the absence and presence of surface active non-wetting agents.
26

Production And Characterization Of Activated Carbon From Hazelnut Shell And Hazelnut Husk

Cuhadar, Cigdem 01 June 2005 (has links) (PDF)
In this study, the pore structures and surface areas of activated carbons produced from hazelnut shell and hazelnut husk by chemical activation technique using phosphoric acid (H3PO4), at relatively low temperatures (300, 400 and 500oC), were investigated. Raw materials were impregnated with different H3PO4 solutions of 30%, 40%, 50% and 60% by weight. To produce activated carbon, acid impregnated samples were heated / at a heating rate of 20 oC/min to the final carbonization temperature and held at that temperature for 2 hours. The volume and surface areas of mesopores (2-50 nm) and BET surface areas of the samples were determined by N2 gas adsorption technique at -195.6oC. The pore volume and the area of the micropores with diameters less than 2 nm were determined by CO2 adsorption measurements at 0oC by the application of Dubinin Radushkevich equation. N2 (BET) surface areas of the hazelnut shell and hazelnut husk based activated carbons were in the range of 242-596 m2/g and 705-1565 m2/g, respectively. CO2 (D-R) surface areas of the hazelnut shell and hazelnut husk based activated carbons were in the range of 433-576 m2/g and 376-724 m2/g, respectively. The highest BET surface area was obtained as 596 m2/g among hazelnut shell based samples (HS 60.4 / shell impregnated with 60 wt.% H3PO4, carbonized at 400 &ordm / C) and as 1565 m2/g among hazelnut husk based samples (HH 40.4 / husk impregnated with 40 wt.% H3PO4, carbonized at 400 &ordm / C). Hazelnut shell based activated carbons were mainly microporous while hazelnut husk based ones were mesoporous.
27

Economically beneficial drug interactions with cyclosporin and tacroliumus : clinical studies in recipients of kidney and liver transplants / by T.E. Jones.

Jones, Terence Edward January 2000 (has links)
Bibliography: leaves 234-257. / xi, 277 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Three separate clinical studies in organ transplant recipients are presented. The aims are to examine fundamental questions regarding the clinically and economically important pharmokinetic interaction between diltiazem and cyclosporin, an interaction widely utilised in organ transplantation. The data contained should assist the development of soundly based policies that will ensure a benefit exists before a sparing agent is coprescribed, and that the lowest effective dose of sparing agent is used. / Thesis (Ph.D.)--University of Adelaide, Dept. of Clinical and Experimental Pharmacology, 2001
28

Improved oral bioavailability of poorly water soluble drugs using rapid freezing processes

Overhoff, Kirk Alan, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.
29

Enhancing the delivery of poorly water soluble drugs using particle engineering technologies

Sinswat, Prapasri, January 1900 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.
30

Therapeutic miR-506-3p Replacement in Pancreatic Carcinoma Leads to Multiple Effects including Autophagy, Apoptosis, Senescence, and Mitochondrial Alterations In Vitro and In Vivo

Borchardt, Hannes, Kogel, Alexander, Kalwa, Hermann, Weirauch, Ulrike, Aigner, Achim 03 November 2023 (has links)
Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer mortality. Considering its very poor prognosis, novel treatment options are urgently needed. MicroRNAs (miRNAs) are involved in the regulation of various physiological and pathological processes. In tumors, aberrant downregulation of given miRNAs may result in pathological overexpression of oncogenes, rendering miRNA replacement as a promising therapeutic strategy. In different tumor entities, miRNA-506-3p (miR506-3p) has been ambivalently described as tumor suppressing or oncogenic. In PDAC, miR-506 is mainly considered as a tumor-suppressing miRNA. In this study, we extensively analyze the cellular and molecular effects of miRNA-506-3p replacement in different PDAC cell lines. Beyond profound antiproliferation and induction of cell death and autophagy, we describe new cellular miR506-3p effects, i.e., induction of senescence and reactive oxygen species (ROS), as well as alterations in mitochondrial potential and structure, and identify multiple underlying molecular effects. In a preclinical therapy study, PDAC xenograft-bearing mice were treated with nanoparticle-formulated miRNA-506 mimics. Profound tumor inhibition upon systemic miRNA-506 administration was associated with multiple cellular and molecular effects. This demonstrates miRNA replacement as a potential therapeutic option for PDAC patients. Due to its broad mechanisms of action on multiple relevant target genes, miR506-3p is identified as a particularly powerful tumor-inhibitory miRNA.

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