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Akhter, Rehan. "Laser welding of zinc coated steel". Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/8164.
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Weirman, Chris. "An examination of the corrosion resistance of zinc-magnesium and zinc-aluminium-magnesium coated steels". Thesis, Swansea University, 2011. https://cronfa.swan.ac.uk/Record/cronfa43111.
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This project has investigated the development of the optimum combination levels and processing conditions for zinc and magnesium coatings deposited by a Physical Vapour Deposition (PVD) process under investigation by Tata Steel Europe Ltd. Temperatures in the range of 100°C to 350°C and times ranges of 2-10 hours and 30 -300 seconds were investigated and the coatings characterised by optical microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analysis, (EDX), also known as electron probe microanalysis (EPMA), glow discharge optical emission spectrophotometry (GDOES) and X-ray diffraction (XRD), and examined for corrosion resistance using the scanning vibrating electrode technique (SVET) and accelerated weathering cabinet tests; prohesion and salt spray. The work has shown that the initial zinc magnesium coatings prepared via the developing Tata Steel Europe PVD process did not perform as well as the current and developing hot dipped zinc-aluminium or zinc-aluminium-magnesium alloys in continuously submerged sodium chloride solutions. In support of this work, and to contrast the coatings prepared via the PVD process, the project investigated changes to the coating composition and substrate gauge of a range of conventionally prepared hot dip galvanised samples. This part of the project has looked at variations in the alloying additions to zinc using magnesium in the range of 0-2wt% and aluminium in the range of 0-5wt%. Changing coating composition and/or changing processing conditions produced coatings with dendrites per mm2 (dendrite number) ranging from 350 to 7600. Primary zinc% has also been found to vary in the range of 29% to 95% and the relative corrosion rates have been found to vary between 49% and 477% that of benchmark samples of conventional hot-dip galvanised steel of 275g/m2. Conventional and more recently developed coatings have been studied in mildly alkaline environments by immersion mass loss and SVET testing, as part of a study to investigate if Tata Steel Europe can substitute a lower coating weight, newly developed MagiZinc metallic coating into construction industry in the UK. It was found that both conventional and the new alloy chemistries were seen to have sufficient coating weight after the 28 days, the total cement curing time, to allow the substitution.
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Bolyard, Stephanie Carbone. "Fate of Coated Zinc Oxide in Municipal Solid Waste Landfills". Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5133.
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Given the increase in nanomaterial (NM) use in consumer products and the large fraction of waste placed in landfills worldwide, the probability of these products reaching municipal solid waste (MSW) landfills at the end of their useful life is high. Since nanotechnology use is still in its early stages, there are currently no regulations pertaining to the disposal of NMs and their fate in MSW landfills is still unknown. Understanding the fate of NMs in MSW landfills is vital to ensure the proper handling of these novel materials from cradle to grave; such research will provide information on how these NMs can be safely introduced into the environment. This research seeks to understand the fate of NMs within waste environments by examining the interactions between NMs and landfill leachate components. The primary focus of this thesis is the effect of Zinc Oxide (ZnO) on biological landfill processes, solids aggregation, and chemical speciation of Zn in landfill leachate following the addition of crystalline, nano-sized ZnO coated with triethoxycaprylylsilane. This research (1) observed the effects of coated ZnO on five-day biochemical oxygen demand (BOD5) and biochemical methane potential (BMP), (2) examined effects of solids aggregation on the fate of ZnO, (3) quantified the concentration of Zinc (Zn) by size fractions, and (4) modeled the chemical speciation of Zn in landfill leachate using Visual MINTEQ. No change in dissolved Zn was observed after coated ZnO was exposed to "middle-aged" leachate. Upon exposure to “mature” leachate there was an increase in dissolved Zn assumed to be a result of the dissociation of ZnO. Solids data supported the aggregation of particles in both middle aged and mature leachate. There was an increase in the Zn concentration in leachate fractions greater than 1500 nm presumably due to the dispersion of normally insoluble ZnO nanoparticles (NPs) following the interaction with humic acids (HA). ZnO did not inhibit anaerobic or aerobic processes in either middle aged or mature leachate, presumably due to the relatively low concentration of dissolved ionic Zn. Despite the observation of increased dissociation upon exposure to mature leachate, the presence of dissolved organic matter (DOM) may have hindered the ability for dissolved ionic Zn to become bioavailable. Fractionation, BOD5 and BMP tests, and chemical speciation modeling provided insight on the mobility of ZnO in landfills and the absence of inhibitory effects on landfill processes. Aggregation of ZnO NPs may prevent movement through traditional containment systems (i.e. geomembrane liners) due to the increased particle size. However, the increased dispersion suggests that ZnO NPs will be transported out of the landfill in the leachate, however biological treatment of leachate should be unaffected by the presence of ZnO. The bioavailability of Zn was not substantially affected by the presence of ZnO due to affinity of dissolved Zn for DOM. However, due to the heterogeneity of landfill leachate and the utilization of different NM coatings, it is challenging to predict the overall mobility of other NMs in a landfill.ID: 031001302; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: .; Title from PDF title page (viewed March 15, 2013).; Thesis (M.S.Env.E.)--University of Central Florida, 2012.; Includes bibliographical references (p. 85-97).
M.S.Env.E.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Environmental Engineering
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Jang, Yohan. "THE TRIBOLOGY AND FORMABILITY OF ZINC COATED STEEL SHEETS SUBJECTED TO DIFFERENT STRAIN STATES". Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1270093768.
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Thesis (Master of Sciences (Engineering))--Case Western Reserve University, 2010Department of Materials Science and Engineering Title from PDF (viewed on 2010-05-25) Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
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Trautmann, Andreas. "Bifocal hybrid laser welding : a technology for welding of aluminium and zinc-coated steels /". München : Utz, 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=9783831608768.
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Trautmann, Andreas. "Bifocal hybrid laser welding a technology for welding of aluminium and zinc-coated steels". München Utz, 2008. http://d-nb.info/992520797/04.
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English, Michael David. "Gold coating of silica and zinc oxide nanoparticles by the surface reduction of gold(I) chloride". Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/51084/1/Michael_English_Thesis.pdf.
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The possibility of a surface inner sphere electron transfer mechanism leading to the coating of gold via the surface reduction of gold(I) chloride on metal and semi-metal oxide nanoparticles was investigated. Silica and zinc oxide nanoparticles are known to have very different surface chemistry, potentially leading to a new class of gold coated nanoparticles.
Monodisperse silica nanoparticles were synthesised by the well known Stöber protocol in conjunction with sonication. The nanoparticle size was regulated solely by varying the amount of ammonia solution added. The presence of surface hydroxyl groups was investigated by liquid proton NMR. The resultant nanoparticle size was directly measured by the use of TEM.
The synthesised silica nanoparticles were dispersed in acetonitrile (MeCN) and added to a bis acetonitrile gold(I) co-ordination complex [Au(MeCN)2]+ in MeCN. The silica hydroxyl groups were deprotonated in the presence of MeCN generating a formal negative charge on the siloxy groups. This allowed the [Au(MeCN)2]+ complex to undergo ligand exchange with the silica nanoparticles, which formed a surface co-ordination complex with reduction to gold(0), that proceeded by a surface inner sphere electron transfer mechanism. The residual [Au(MeCN)2]+ complex was allowed to react with water, disproportionating into gold(0) and gold(III) respectively, with gold(0) being added to the reduced gold already bound on the silica surface. The so-formed metallic gold seed surface was found to be suitable for the conventional reduction of gold(III) to gold(0) by ascorbic acid. This process generated a thin and uniform gold coating on the silica nanoparticles.
This process was modified to include uniformly gold coated composite zinc oxide nanoparticles (Au@ZnO NPs) using surface co-ordination chemistry. AuCl dissolved in acetonitrile (MeCN) supplied chloride ions which were adsorbed onto ZnO NPs. The co-ordinated gold(I) was reduced on the ZnO surface to gold(0) by the inner sphere electron transfer mechanism. Addition of water disproportionated the remaining gold(I) to gold(0) and gold(III). Gold(0) bonded to gold(0) on the NP surface with gold(III) was reduced to gold(0) by ascorbic acid (ASC), which completed the gold coating process.
This gold coating process of Au@ZnO NPs was modified to incorporate iodide instead of chloride. ZnO NPs were synthesised by the use of sodium oxide, zinc iodide and potassium iodide in refluxing basic ethanol with iodide controlling the presence of chemisorbed oxygen. These ZnO NPs were treated by the addition of gold(I) chloride dissolved in acetonitrile leaving chloride anions co-ordinated on the ZnO NP surface. This allowed acetonitrile ligands in the added [Au(MeCN)2]+ complex to surface exchange with adsorbed chloride from the dissolved AuCl on the ZnO NP surface. Gold(I) was then reduced by the surface inner sphere electron transfer mechanism. The presence of the reduced gold on the ZnO NPs allowed adsorption of iodide to generate a uniform deposition of gold onto the ZnO NP surface without the use of additional reducing agents or heat.
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Holden, Nicholas John. "The improvement of weld quality in medium frequency direct current resistance spot welding". Thesis, Birmingham City University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312224.
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Zinc coated steels are widely used in the automotive industry, because of the improved protection against corrosion. Their use has consequences for the resistance welding process, which is the most widely used method of joining body panels. The zinc coating alloys with the copper electrode, resulting in increased electrode wear, and a reduction in electrode life. The welding current must be increased, because of the reduced contact resistance and thus heavier cables and power sources are required. A novel form of power source, the Medium Frequency Direct Current inverter, offers advantages over the traditional AC transformer. The higher operating frequency results in a lighter transformer, and a smaller welding current may be used, because the DC welding current generates heat at a constant rate, and is thus more effective than an AC power source. A potential advantage of this technology is that the increased frequency allows improved resolution in monitoring and control. Novel signal conditioning circuitry was developed, allowing significant improvement in the time resolution of the voltage and resistance signals. A series of welding trials was conducted, while monitoring the welding process. The correlation between weld quality and various process variables was assessed, and a control algorithm to compensate for electrode wear was proposed. This algorithm, based on a constant voltage principle, was implemented on a bespoke welding timer. A significant improvement in electrode life was obtained using this technique. The control algorithm was shown effective experimentally, but practical limitations do not permit testing under all possible conditions. A numerical model of the spot welding process, using Finite Difference technique, was developed. Following successful validation, the model was used to predict the performance of the control algorithm under various conditions of electrode wear. The results indicate that a constant voltage algorithm can compensate for an increase in electrode tip diameter, but that a change in contact resistance may result in unsatisfactory welds.
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Reid, Rhoades Pamela Gail. "Growth responses of Marigold, Zinnia and Vinca grown in 288 plug trays coated with zinc chloride compounds". Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11062007-175849.
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Van, Zandt Nicholas L. "Aqueous Fabrication of Pristine and Oxide Coated ZnSe Nanoparticles". Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1623356039586297.
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Accardi, Adrienne. "Corrosion of Dual Coated Reinforcing Steel with Through-Polymer Breaks in Simulated Concrete Pore Solution". Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1556.
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This investigation is an examination of the behavior of dual coated reinforcing steel (DCR) with defects in the polymer coating exposing the only zinc layer in simulated concrete pore solution with and without chlorides. The intentional defects simulated the condition typically experienced by the rebar in service. Specimens were tested at open circuit potential, +100 mV, -500 mV, and -1000 mV for 30 to 100 days. The results were compared with that from previous DCR investigation with to-steel defects and epoxy-coated rebar (ECR). DCR with to-zinc defects had extensive corrosion damage when under strong anodic polarization and exposed to chlorides and was similar to that seen for DCR with to steel defects. The freely corroding (OCP) to-zinc DCR specimens in solutions both with and with no-chlorides experienced initially very active dissolution which ended after ~1 day. The zinc exposed at the coating breaks was not completely consumed even after 100 days and there was no visible corrosion product accumulation. This may be due to the formation of a calcium hydroxyzincate passive film and shows that the zinc passivates in alkaline solutions without the benefit of a crevice environment. The DCR with to-steel defects and the DCR with to-zinc defects had similar amounts of disbondment for all test conditions. Notable disbondment was seen only in highly anodic polarization regime with chlorides and was due to large amounts of solid corrosion product formation. These results suggest then that the overall process of zinc wastage in DCR in concrete pore water is not likely to be rapid, which would be beneficial to extending the period in which the barrier and galvanic properties of the zinc are maintained.
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Hoey, Thomas Michael. "Evaluation of high temperature performance of the Co-Cr-C coated P92 steel". Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39989/.
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The motivation to increase the operation temperatures of fossil fuel power plant is primarily to improve power plant efficiency and reduce the negative environmental impact of fossil fuel power plant emissions. A main limitation to higher temperature operation is the enhanced oxidation damage of materials at increased temperatures. One of the most concerning areas of enhanced damage is on the inside surface of P92 ferritic steel (~ 9 % Cr) pipework which is used primarily to carry high temperature steam from the boiler. To combat the oxidation damage of P92 the energy industry has recently begun investigating the application of oxidation resistant coatings to P92 to enable higher temperature operation. Aluminium diffusion coatings have been the focus to date but they have been found to have a number of limitations, including coating degradation/porosity and a detrimental effect on the creep properties of the substrate, in part due to the high temperature coating process. Although other lower temperature coating methods, such as thermal spraying, have been considered these are limited by the practicalities and economics of spraying on the inside surface of P92 pipework. Therefore there is a real industrial need for consideration of a new coating type, for the inside of P92 pipework, which can be applied at low temperature and is also economical at full scale. This is where this thesis contributes by considering an electro-deposited Co-Cr-C coating never previously considered for this application. The Co-Cr-C type coating is electro-deposited to ~ 34-37 µm onto P92 ferritic steel. The coating is composed of ~ 35 wt % Cr3C2 electro-deposited within a cobalt matrix. The free-standing coating material and coated P92 system were subjected to isothermal oxidation in air and the oxidised state was characterised by a range of microstructural techniques. Oxidation behaviour, microstructural evolution and inter-diffusion between coating and substrate have all been considered. Thermo-Calc thermodynamic software has been used to make predictions about the long term evolution of the system. A series of uncoated and coated mechanical tests (creep, fatigue, creep-fatigue) have also been performed to assess the effect of coating application on the mechanical properties of P92 steel. This research has been motivated by industry at all stages and close collaboration has allowed for the most industrially relevant test conditions to be determined. Overall the Co-Cr-C coating is shown to be an industrially promising coating technology for application to P92. The study within this thesis shows that the good oxidation properties, interface behaviour and mechanical properties, combined with low temperature deposition and easy scale up, make this a viable coating for further development. It also has a number of advantages over the current aluminium coatings. The work within this thesis serves as a detailed feasibility and industry case study for further in-house testing by industrial sponsors, before future commercialisation of the product. A discussion of potential future work is also included at the end of the thesis.
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Condon, Aiko Kondo. "Investigation of zinc uptake processes by manganese-oxide-coated sediments from a mining-contaminated stream, Pinal Creek, Arizona". Thesis, The University of Arizona, 2003. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0081_sip1_w.pdf&type=application/pdf.
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Ramashia, Thinavhuyo Albert. "Effect of the additional electron acceptor in hybrid ZnO: P3HT:PCBM spin-coated films for photovoltaic application". University of the Western Cape, 2015. http://hdl.handle.net/11394/4779.
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>Magister Scientiae - MScIn a quest for low operational and maintenance cost solar cell devices, organic photovoltaics remain a potential source of energy worthy to be explored. In order to generate cost- effective electricity from solar energy, either the efficiency of the solar cells must be improved or alternatively the manufacturing cost must be lowered. The power conversion efficiency (PCE) of organic photovoltaics is influenced by the choice of electron acceptor material, the structure of the polymer, the morphology of the film, the interfaces between the layers and the ratio between the electron acceptor material and the polymer. Nevertheless, efficiency is still limited compared to conventional silicon based PV cells due to low mobility of charge carriers with a short exciton diffusion length in the active layer. Currently, hybrid solar cells have been considered as one of the most promising concepts to address the limited efficiency of organic solar cells. Therefore in this thesis ZnO nanoparticles were synthesized using hydrothermal assisted method. These nanoparticles were incorporated in the poly (3-hexylthiophene) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM), and used as additional acceptors of electrons released from the polymer donor material, with the anticipation to increase the electron mobility, and ultimately the PCE. The thermo-gravimetric analyses revealed improved thermal stability of P3HT upon incorporating ZnO in the polymer matrix. X-ray diffraction analyses revealed that the diffraction peaks shift to higher angles when incorporating the ZnO in the P3HT:PCBM surface and this is consistent with the Raman observation. The photovoltaic properties demonstrated that the addition of ZnO nanoparticles in P3HT:PCBM bulk-heterojunction increases PCE from a baseline of ∼1.0 % in the P3HT:PCBM system to 1.7% in the P3HT:PCBM:ZnO ternary system. The enhanced PCE was due to improved absorption as compared to its counterparts. Upon increasing the addition of ZnO nanoparticles in the P3HT:PCBM matrix, the PCE decreases, due to a large phase separation between the polymer, PCBM and ZnO induced by ZnO agglomerations which resulted in increased surface roughness of the active layer. These findings signify that incorporation of ZnO nanostructures in the P3HT:PCBM polymer matrix facilitates the electron transport in the photoactive layer which results to improved efficiency.
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Yue, Weizhou. "Liposome-coated Magnesium Phosphate Nanoparticle for Delivery of Cytochrome C into Lung Cancer Cells A549". Scholarly Commons, 2017. https://scholarlycommons.pacific.edu/uop_etds/2987.
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Proteins are large biomolecules that have great therapeutic potential in treating many human diseases. However, chemical/enzymatic degradation, denaturation, and poor penetration into cells are some of the challenges for clinical use of intracellular proteins.
Previously, our group has developed cationic lipid-coated magnesium phosphate nanoparticle (LP MgP NP-CAT) formulations to enhance the intracellular delivery of the negatively charged protein catalase. The goal of the current research is to develop a formulation to deliver cytochrome c (CytC), a positively charged protein into lung cancer cells A549. Specifically, this thesis research prepares and tests liposome-coated magnesium phosphate nanoparticle for delivery of cytochrome c (CytC LP/MgP).
CytC LP/MgP was designed, prepared and characterized, showing that it had an average diameter around 150 nm and ζ-potential around +30 mV. The morphology of CytC LP/MgP was validated by transmission electron microscopy.
CytC LP/MgP successfully led to the attachment of CytC to A549 cells, as supported by fluorescence imaging. Intracellular delivery of CytC alleviated the cytotoxicity of cationic lipids in A549 cells, as suggested by the MTS assay on cell viability, which could facilitate the clinical use of cationic lipids in drug delivery systems.
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Qian, Xin. "Cobalt-Catalyzed C-C and C-N Coupling reactions". Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00943479.
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Ce travail de these a permis le déveloippement de nouvelles reactions de couplage catalysées par des sels de cobalt(II) Le premier chapitre décrit l'allylation cobalta catalysée d'halogénures d'alkyles. La méthode est facile à mettre en œuvre, efficace avec une grande variété d'halogénures d'alkyes et des acétates ou carbonates d'allyle substitués. Les rendements vont de bons à excellents et la tolérance fonctionnelle élevée. Dans le cas d'acétates d'allyle substitués le produit linéaire est obtenu majoritairement ou exclusivement. Quelques expériences ont permis de mettre en lumière la formation d'espèce radicalaire lors du cycle catalytique. Les premiers essais pour étendre cette méthodologie aux couplages allyle-allyle et alkyle-alkyle sont également décrits. Le deuxième chapitre porte sur l'amination catalysée au cobalt d'organozinciques fonctionnalisés en utilisant des N-chloroamines. La procédure est simple et générale et demande des conditions plus douces que celles précédemment décrite, tout en tolérant un très large éventail de substrats, avec une bonne tolérance à de nombreux groupes fonctionnels. Les premiers essais pour étendre la méthodologie à la réaction entre un organozincique et une source électrophile de soufre en vue de former des liaisons C-S sont également exposés. Enfin le dernier chapitre décrit la réaction d'organozinciques engendrés par catalyse au cobalt avec une source " verte " de cyanure électrophile, N-cyano-N-phenyl-p-methyl-benzenesulfonamide (NCTS), pour conduire avec de bons rendements aux arylnitriles correspondants. Des sources analogues de CN+ ont également été testées.
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Feray, Laurence. "Triéthylborane et diéthylzinc : agents de transfert de chaîne dans les réactions d'additions radicalaires sur doubles liaisons C=N et C=C. Stéréoinduction dans les additions sur les imines de glyoxylates". Aix-Marseille 3, 2000. http://www.theses.fr/2000AIX30001.
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Le triethylborane et le diethylzinc se sont reveles etre de bons agents de transfert de chaine dans les reactions d'addition de radicaux alkyle secondaires et tertiaires sur les imines de glyoxylates. Les produits formes sont des aminoesters -alkyles, precurseurs potentiels d'acides amines non naturels. Dans ces processus, ces deux reactifs jouent un triple role, le role d'amorceur, le role d'agent de transfert de chaine et le role d'acide de lewis en complexant l'atome d'azote de l'imine. Des reactions realisees sur une serie d'imines derivees d'amines chirales conduisent a de bonnes diastereoselectivites lorsque le diethylzinc, agent complexant bidentate, est utilise comme mediateur de la reaction radicalaire. Ce nouveau procede, qui offre une alternative a l'utilisation des derives de l'etain reputes toxiques, a ete applique avec succes a d'autres accepteurs de radicaux tels que les ethers d'oximes et les hydrazones glyoxyliques, et la cyclohexenone.
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Lepage, Lynne Marie Gisele. "Effects of dietary zinc deficiency and malnutrition on the T-lymphocyte zinc-finger protein p56[1]c[superscript]k[superscript] in mice". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq23380.pdf.
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Richards, Mark Rowse. "Process development for IrAl coated SiC-C functionally graded material for the oxidation protection of graphite /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/10574.
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Boutard, Nicolas. "Nouvelles voies d’accès aux alpha-aminoacides c-glycosylés en position non-anomérique". Montpellier 2, 2006. http://www.theses.fr/2006MON20135.
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Whiting, Steven Nicholas. "Metal mobilisation and uptake by the zinc hyperaccumulator Thlaspi caerulescens J. and C. Presl". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300224.
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Sasi, Abdalla Suliman. "Energy efficiency of solar heat concentrators using glass coated Al doped ZnO transparent conducting oxide as selective absorber". Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2699.
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Thesis (Master of Engineering in Mechanical Engineering)--Cape Peninsula University of Technology, 2017.Transparent conductive oxides (TCOs), which are widely used in transparent electronics, possess a spectral selectivity that is suitable for a solar material absorber. TCO materials have a plasma wavelength in the infrared region. Consequently electromagnetic waves shorter than a plasma wavelength are transmitted through the material, while longer electromagnetic waves are reflected on the surface. In contrast to the opaque solar selective absorbers, the plasma wavelength in TCO materials can be easily tuned by controlling the heavy doping process to match the peak shift of thermal radiation at higher temperatures. Furthermore, the use of TCO in conjunction with a solar absorber relaxes the spectral selectivity of the latter and thus widens the selection of the solar absorber; subsequently the only requirement is a thermally stable black body. Aluminum doped Zinc Oxide (AZO) is a class of TCO materials which is cost effective to manufacture due to abundance ZnO, and Aluminum raw materials. This thesis is based on the synthesis of Al doped ZnO thin films nanostructure using radio frequency RF magnetron sputtering process. The influence of the deposition parameters, including argon working pressure and substrate temperature, on the structural and optical properties of the AZO thin films is investigated by means of X-ray diffraction (XRD) and optical spectroscopy (UV-VIS-NIR). The optical constants of AZO films are extracted from transmittance and reflectance spectra using a combination of Drude and Lorentz dielectric function model. A computer simulation is developed to calculate the radiative properties of Al doped ZnO thin films nanostructure. The thermal emittance and solar absorptance is predicted indirectly from optical reflectance and transmittance of AZO films by invoking Kirchhoff’s law. A Special attention has been paid to the parameters that influence the spectral properties of the AZO films including carrier’s mobility, Al doping concentration and film thickness. Carrier’s mobility turned out to have the most significant influence on the spectrally selective performance of AZO films.
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Gill, Harvinder Singh. "Coated microneedles and microdermabrasion for transdermal delivery". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24711.
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Thesis (Ph.D.)--Bioengineering program, Georgia Institute of Technology, 2008.Committee Chair: Dr. Mark R. Prausnitz; Committee Co-Chair: Dr. Mark Feinberg; Committee Member: Dr. Mark Allen; Committee Member: Dr. Niren Murthy; Committee Member: Dr. Peter Hesketh; Committee Member: Dr. Robert Swerlick
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Marty, Fabrice. "Fer, cuivre, zinc, sélénium dans l'hépatite chronique C traitée par interféron : étude comparative répondeurs/non répondeurs". Bordeaux 2, 1995. http://www.theses.fr/1995BOR23020.
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Nuñez, Moreno Jesus Humberto. "Nutritional Studies on Pecans [Carya illinoinensis L. (Wangenh.) C. Koch] Growing in Irrigated Alkaline Soils". Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/194206.
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Annual application of N at rates of 118 (118N), 236 (236N), and 354 (354N) kg•ha⁻¹ on 35 year old 'Western Schley' pecan trees during four years had little effect on mineral composition and foliar N. No differences in yield, nut quality, and reproductive characteristics were found. Alternate bearing intensity in four consecutive years was 37, 33 and 28% in 118N, 236N, and 354N, respectively, with a significant linear response. Rates from 118 to 236 kg N•ha⁻¹ satisfy N needs for pecan in irrigated pecan orchard of the southwest of United States. The effect of one-time banding of zinc sulfate (74 kg Zn•ha⁻¹) and zinc-EDTA (19 kg Zn•ha⁻¹) was evaluated over a period of four years on ‘Wichita’ pecans growing in alkaline soil. Significant differences in foliar Zn levels were found one month after application of Zinc-EDTA. Differences also were noted during the next three years on approximately 25% of the sampling dates. Yield, leaflet area, and trunk cross sectional area were not affected. Zinc-EDTA increased Zn uptake by 'Wichita' pecan trees in alkaline conditions during three years. A field study indicated that manure or manure plus Zn increased foliar Zn levels in pecans after two years of annual applications. Manure (24 ton ha⁻¹) plus zinc sulfate (258 kg Zn•ha⁻¹ as zinc sulfate) treatment had the highest foliar Zn levels. No differences were observed in trunk growth, leaf area, leaf weight, nut filling, and yield. Manganese toxicity symptoms are exhibited when leaf Mn levels are higher than 1700 μg•g⁻¹ during the standard date sampling of July and affected reproductive characteristics and leaf and shoot growth. More severe visible symptoms include delayed budbreak and die-back of young shoots. In potted pecan trees, zinc EDTA treated trees had a foliar Zn of 244 μg•g⁻¹, in foliar sprayed trees (eight foliar sprays of a combination of zinc sulfate and UAN32) had 140 μg•g⁻¹, and in control trees had 33 μg•g⁻¹. Soil adsorption isotherms showed that of the three fertilizers evaluated Zn sulfate was adsorbed most strongly by the soil (1.5 mg Zn•g⁻¹ of soil). Soil adsorption from Zn EDTA solutions was insignificant.
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Rakotomahefa, Manitra [Verfasser], i M. [Akademischer Betreuer] Scherge. "Fundamentals of lubricated friction in deep drawing of zinc coated sheet metal considering contacting surface morphology and chemistry / Manitra Rakotomahefa ; Betreuer: M. Scherge". Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1207393053/34.
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Westman, Belinda J. "Studies on the interactions mediated by the C-terminal zinc finger domains of Ikaros-family proteins". Thesis, The University of Sydney, 2003. https://hdl.handle.net/2123/27872.
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Ikaros-family transcription factors play important roles in the control of
haematopoiesis. Family members are predicted to contain up to six classical
zinc fingers that are arranged into N- and C-terminal domains. The N-terminal
domain is responsible for site-specific DNA binding, whereas the C-terminal
domain mediates primarily the homo- and hetero-oligomerisation between
family members. Although the mechanisms of action of these proteins are not
completely understood, the zinc finger domains are known to play a central
role. The work presented here was performed to further elucidate the physical
and functional properties of the C-terminal domain, in particular, the C-terminal
domain of Eos.
A range of biophysical techniques was used to demonstrate that the C-terminal
domain of Eos mediates the formation of complexes that consist of
nine or ten molecules. This result is highly unusual in the context of what is
currently known about transcription-factor biology. In order to gain insight into
the structural basis of oligomerisation, NMR spectroscopy was used to
determine the solution structure of the second zinc finger from the C-terminal
domain of Eos. This structure exhibited several unusual properties for a zinc
finger, and these may contribute to the basis for the inability of this domain to
bind DNA. Finally, alanine-scanning mutagenesis revealed residues that are
involved in the homo-oligomerisation of E03, and these results are discussed
in the context of the structure of the C-terminal domain. This work has not only
shed light onto the mechanisms through which lkaros-family proteins regulate
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Xu, Yongli. "High Jc Epitaxial YBa2Cu3O7-δ Films Through a Non-Fluorine Approach for Coated Conductor Applications". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1075992286.
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Ballardini, Marco. "Caratterizzazione del comportamento a fatica di acciaio per serrature con diversi trattamenti superficiali". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14421/.
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Questo elaborato si pone come scopo quello di caratterizzare il comportamento a fatica di un acciaio super-rapido, UNI EN 10087 - 11 S Mn Pb 30, con il quale verrà realizzata l’asta scrocco di una serratura di nuova concezione.
Per motivi di progettazione, al fine di migliorare le caratteristiche tribologiche del materiale, è stato ipotizzato di apporre su questo acciaio un rivestimento metallico, ottenuto per elettrodeposizione galvanica, di zinco (ISO 2081 - Fe/Zn8 c1A) o nichel (ISO 1458 Fe/Cu1 Ni5s).
Inevitabilmente questi rivestimenti hanno un’influenza sulla vita a fatica del materiale, da qui lo studio di cui si occupa questo testo, che porterà ad un confronto tra il materiale non trattato e rivestito, soffermandosi sul rivestimento metallico di zinco.
I dati ricavati dai test a fatica a flessione rotante, effettuati come prescritto da ISO 1143:2010, sulle serie, vengono analizzati in primo luogo secondo quanto prescritto da ISO 12107:2017 e successivamente confrontati mediante una variante del metodo ANOVA per il confronto di curve SN al fine di determinare l'effettiva influenza del rivestimento sulla proprietà di resistenza a fatica ad alto numero di cicli.
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Frank, Deborah Jean. "Regulation of cell growth in C. elegans and D. melanogaster by ncl-1/brat /". Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5029.
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Begouin, Jeanne-Marie. "Activation de composés aromatiques et hétéroaromatiques pour la formation de liaisons C-C et C-N par catalyse au cobalt". Thesis, Paris Est, 2009. http://www.theses.fr/2009PEST0033.
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Les réactions de couplage croisé catalysées par des métaux de transition permettant la formation de liaisons C-C et C-hétéroatome sont à la base de la synthèse d’intermédiaires clefs pour la chimie pharmaceutique, la chimie supramoléculaire et la chimie des matériaux. Cependant, certains catalyseurs métalliques utilisés sont reconnus comme étant assez coûteux ou toxiques. Le développement de catalyseurs alternatifs peu coûteux et écologiques, tels que les catalyseurs à base de cobalt qui ont déjà montré leur efficacité pour la formation de liaisons C-C, fait donc l’objet d’études. Nous avons décidé d’utiliser des organozinciques aromatiques fonctionnalisés, obtenus facilement à l’aide d'une réaction catalysée par CoBr2, dans des réactions de couplage catalysées par CoBr2 avec des chloro-diazines et -triazines aboutissant à la synthèse d’aryldiazines et -triazines. Des organozinciques benzyliques ont également pu être utilisés dans ces réactions permettant la synthèse de benzyltriazines. Nous avons également envisagé l’utilisation d’autres types de substrats. Des réactions de couplage catalysées par CoBr2 entre des organozinciques aromatiques et des méthylthiopyrimidines ou le 2- méthylthiobenzo[b]thiazole ont ainsi été réalisées, conduisant à la synthèse de 2,4- diarylpyrimidines ou de 2-arylbenzo[b]thiazoles. Nous avons également étudié la réactivité des dérivés du benzonitrile dans les couplages directs catalysés par CoBr2 avec des halogénures aromatiques basés sur l’activation de la liaison C-CN pour former des biaryles. Enfin, des réactions de couplage croisé C-N entre des halogénures aromatiques et l’aniline conduisant à la synthèse de diarylamines ont été étudiéesTransition metal-catalyzed cross-coupling reactions allowing the formation of C-C or C-Heteroatom bonds underlie the synthesis of key intermediates for pharmaceutical, supramolecular chemistry and material sciences. Thereby, the development of these methodologies is prominent and an increasing number of studies are devoted to these processes. However, some metallic catalysts are known to be rather expensive or toxic. Consequently, the development of alternative sustainable catalysts such as cobalt or ironbased catalysts has been studied over the past few years. Cobalt-catalysts have been little-used although they have shown to be effective for various C-C bond forming reactions. Functionalized arylzinc reagents can be readily obtained from the corresponding arylhalides using a CoBr2-catalyzed reaction. First we envisioned using these arylzinc reagents in CoBr2-catalyzed cross-coupling reactions with chlorodiazines and chlorotriazines leading to aryldiazines and aryltriazines. Benzylzinc reagents had also been used in these reactions and we synthesized various benzyltriazines in this manner. We also studied whether we can use other kind of substrates in these reactions. Thus, we performed CoBr2-catalyzed cross-coupling reactions between arylzinc reagents and methylthiopyrimidines or methylthiobenzo[b]thiazole derivatives leading to 2,4-diarylpyrimidines and 2- arylbenzo[b]thiazole. Then, we studied the reactivity of benzonitrile derivatives in direct cross-coupling reactions with arylhalide based on C-CN bond activation using CoBr2 as catalyst. Finally, we also carried out the study of CoBr2-catalyzed C-N cross-coupling reactions for the synthesis of diarylamines
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Haines, Ben. "The effects of spatial heterogeneity of zinc and nutrient supply on Thlaspi caerulescens (Brassicaceae) J. and C. Presl". Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394266.
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Dehne, Henry [Verfasser], Andreas [Akademischer Betreuer] Bausch, Andreas [Gutachter] Bausch i Friedrich C. [Gutachter] Simmel. "Dynamic structure formation of DNA-coated colloids guided by enzymatic reactions / Henry Dehne ; Gutachter: Andreas Bausch, Friedrich C. Simmel ; Betreuer: Andreas Bausch". München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1214368700/34.
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Grunenberg, Alfred Teo. "Separation of fluorocarbon gases from a reactor plasma system / Alfred Teo Grunenberg". Thesis, North-West University, 2008. http://hdl.handle.net/10394/2640.
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South Africa has natural resources in mineral feedstock containing gold, manganese, chromium, vanadium, copper, antimony, phosphate rock, uranium, fluorspar and titanium. A high percentage of these ores are exported in unbeneficiated form. There are beneficiation opportunities to transform the raw materials to value-added products, thus increasing employment and stimulating the South African economy.
Fluorocarbon (CxFy) gases can be produced via high-temperature plasma processes, where fluorspar and carbon (CaF2 + C) react at -6000K. These gases are traditionally separated by means of costly and unsafe cryogenic distillation.
The focus of this project is to propose a feasible separation process and to interlink it to a plasma system in order to develop a conceptual plant that can produce 2500 t/a C2F4 and 625 t/a C3F6 safely and cost-effectively, both with 96% purity.
To execute the above a literature survey was done giving vital information on absorption and distillation systems as well as membranes that can be used to separate CF4 from CxFy gas streams at acceptable pressures and temperatures.Thesis (M.Sc. Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus,
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Cho, Chi-kong Lawrence, i 曹智剛. "Structural characterization of C-terminal zinc finger domain of XIAP associated factor 1 (XAF1) and its interaction studies with XIAP". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47044123.
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Ramaya, Sharn. "Synthetic studies towards C-glycosyl amino acids : Part I, The synthesis of C-glycosyl amino acids using zinc reagents; Part II, Approaches towards the synthesis of C-glycosyl amino acids using an imino ene reaction". Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390646.
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Fourmentin, Richard Reumont Guy. "Modélisation thermodynamique du système Fe-Zn-Al-Cr à 460°C et son impact sur les procédés de galvanisation". Villeneuve d'Ascq : Université des sciences et technologies de Lille, 2007. https://iris.univ-lille1.fr/dspace/handle/1908/252.
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Reproduction de : Thèse de doctorat : Sciences des matériaux : Lille 1 : 2004.N° d'ordre (Lille 1) : 3532. Résumé en français et en anglais. Titre provenant de la page de titre du document numérisé. Bibliogr. p. 171-176.
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Rozenfeld, Raphaël. "Etude du site actif de l'aminopeptidase A par modélisation moléculaire et mutagenèse dirigée. Définition du rôle du domaine C-terminal de cette enzyme". Paris 5, 2004. http://www.theses.fr/2004PA05P607.
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L'aminopeptidase A (APA), est responsable in vivo de la production de l'angiotensine III, peptide effecteur du système rénine-angiotensine cérébral, qui exerce un effet stimulateur tonique sur le contrôle central de la pression artérielle. Le blocage de la formation de ce peptide dans le cerveau par un inhibiteur spécifique et sélectif de l'APA entraîne un effet antihypertenseur chez les rats hypertendus. L'APA apparaît donc comme une cible dans le traitement de l'hypertension, ce qui justifie la conception d'inhibiteurs spécifiques et sélectifs de cette enzyme. Pour développer de tels composés, nous étudions la topologie du site actif de l'APA par modélisation moléculaire et mutagenèse dirigée. La fonction des résidus identifiés dans le modèle comme étant impliqués dans la liaison du substrat, et la liaison du calcium, ion activateur de l'APA, a été confirmée par mutagenèse dirigée. Les données apportées dans ces études aideront à la conception rationnelle d'inhibiteurs de l'APAAminopeptidase A (APA) is responsible for the production of angiotensin III in vivo, which is the effector peptide of the brain renin-angiotensin system, by exerting a tonic stimulatory effect on the central control of blood pressure. The blockade of the formation of this peptide in the brain by a selective and specific APA inhibitor leads to a decrease of blood pressure in hypertensive rats. APA is thus a therapeutic target for the treatment of hypertension, which justifies the conception of specific and selective inhibitors of this enzyme. In order to develop such compounds, we study the organization of the APA active site by molecular modeling and site-directed mutagenesis. The role of the residues identified in the model as being involved in the binding of the substrate and of the calcium ion, which activates APA was confirmed by site-directed mutagenesis. The data collected in these studies will help in the rational design of APA inhibitors
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Ren, Hongjun. "Preparation of Condensed N-Heterocycles via Chemoselective Benzylic C-H Activations and Preparation of Alkenylmagnesium Reagents, Allylic Zinc Reagents and their Applications in Organic Synthesis". Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-62454.
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Wang, Ying-Hui. "Molecular interaction of zinc finger domain : study of androgen receptor DNA binding domain and SCA7 domain of Ataxin7 by NMR". Strasbourg, 2010. http://www.theses.fr/2010STRA6018.
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La voie de signalisation du récepteur des androgènes (AR) est impliquée dans la progression du cancer de la prostate, et il a été montré que des mutations dans ce domaine étaient responsables de l'activation constitutive des gènes placés sous le contrôle des hormones androgènes. Une de ces mutations transforme un résidu thréonine du DBD en alanine (T575A). Des expériences permettant de mesurer l'activité de transcription ont permis à l'équipe du Dr. Ceraline à l'IRCAD de montrer que la mutation T575A induit un changement de spécificité du récepteur. Alors que l'activité de promoteurs placés sous le contrôle d'éléments de réponse spécifique de AR diminue, celle des promoteurs placés sous le contrôle d'éléments non spécifique augmente. Ce changement de spécificité est corrélé à une modification de l'affinité du récepteur pour les éléments de réponse spécifiques et non spécifiques. Afin de comprendre le mécanisme de cette "reprogrammation" à l'échelle moléculaire, l'étude structurale des domaines DBD des récepteurs sauvage et muté a été entreprise par RMN. La comparaison des deux structures en solution a montré que la mutation n'altère pas le repliement du domaine et donc que la différence de reconnaissance des éléments de réponse n'est pas liée directement à la structure tridimensionnelle du domaine. Nous avons ensuite cherché à déterminer si l'altération de la fonction n'était pas due à une différence de dynamique de la chaîne peptidique. Afin d'étudier les mouvements moléculaires le long de la chaîne, des mesures de relaxation hétéronucléaire ont été effectuées et ont montré également une grande similarité dans le comportement dynamique des deux domaines, à l'exception d'une région située dans le premier doigt de zinc à proximité d'une histidine (H570), qui est conservée dans l'ensemble de la famille des domaines DBD des récepteurs nucléaires. Cette différence nous a conduit à mesurer, par RMN, le pKa de cette histidine pour les deux protéines. Nous avons ainsi montré que la mutation T575A induit une diminution de 0,5 unité de pH par rapport à la même histidine dans le domaine sauvage. L'analyse de la structure a permis de montrer que cette différence de pKa est liée à la perte d'une interaction entre le groupe hydroxyle de la thréonine 575 et le cycle imidazole de l'histidine. L'effet de la mutation sur le mécanisme de reconnaissance s'explique donc par un effet indirect dans lequel un acide aminé situé à distance de la région d'interaction modifie la surface électrostatique du domaine DBD. L'effet de la charge positive en position 570 sur la spécificité de reconnaissance de l'élément de réponse a ensuite été étudiée en construisant plusieurs mutants portant ou non une charge à cette position (mutants H570R et H570A). Ces études ont permis de confirmer l'importance de cette charge et l'ensemble de nos travaux fournissent un éclairage inédit sur les mécanismes de reconnaissance de l'ADN par les récepteurs nucléaires. .The androgen receptor (AR) is a ligand-activated transcriptional factor and a member of the nuclear receptor super family. AR shares a common structural and functional architecture with other members of nuclear receptors. The DNA binding domain of AR (ARDBD) binds to specific response elements as a homodimer. In the clinic, certain mutations in AR are associated with the progression of prostate cancer and have consequences for the treatment of patients with advanced prostate cancer. Previous studies showed that the mutation T575A, locating in the DNA binding domain, enhances the transcriptional activity regulated by full-length AR on promoters containing the non-specific response element compared to the wild type domain does not. These differences prompted us to study the molecular mechanism of ARDBD wild type and the T575A mutant. Structures of ARDBD wild type and T575A mutant revealed high similarity. However, dynamic behavior showed distinct differences between wild type and T575A mutant domains. The protonation state of H570 in ARDBD was found to be differed by the mutation. This loss of charge of H570 results in changes in transcriptional activity of AR. .
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Morgado, Nazario. "Réalisation d'un anti-reflet bispectral sur substrat de ZnS hémisphérique en technique P. E. C. V. D. : performances et tenue à la pluvio-érosion". Lyon 1, 1997. http://www.theses.fr/1997LYO10185.
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Ce travail a pour objectif de realiser un traitement anti-reflet sur un substrat de zns par p. E. C. V. D. En geometrie hemispherique. Ce traitement optique, performant dans l'infrarouge, doit avoir une bonne resistance en tenue aux tests de pluvio-erosion. Ce traitement est constitue d'un empilement de carbure de germanium, a-gec:h, de differents indices avec une couche de protection de carbone adamantin a-c:h. Dans un premier temps, une etude des conditions de depot nous a permis d'obtenir des couches d'indices variables en fonction des ratio des gaz porteurs, methane et germane. La technique c. V. D. Plasma s'est imposee pour le traitement d'une forme hemispherique avec etude de la geometrie de l'enceinte et des electrodes, ce qui nous a permis d'obtenir une disparite en epaisseur sur l'ensemble de la calotte hemispherique inferieure a 2%. Une caracterisation optique et mecanique, en nanoindentation et pluvio-erosion, nous a permis d'atteindre certaines performances de tenue en pluvio-erosion. Les premiers tests de pluvio-erosion ont mis en evidence un probleme d'adherence des couches de carbure de germanium haut indice sur les substrats de zns. Une analyse de l'interface substrat/couche mince nous a permis de reveler l'attaque des joints de grain du zns par l'element hydrogene contenu dans les differents gaz porteurs et gaz de dilution utilise lors des depots. Par une etude approfondie de la technique de la nanoindentation, nous avons determine deux parametres primordiaux lors de la tenue a la pluvio-erosion : la nanodurete et le module d'elasticite de young des couches minces realisees.
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Iqbal, Abid. "The Sputtering and Characterization of C-Axis Oriented Aluminium Nitride Thin Films On Top Of Cubic Silicon Carbide-On-Silicon Substrates for Piezoelectric Applications". Thesis, Griffith University, 2017. http://hdl.handle.net/10072/365840.
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The growth of micro-scale wireless electronics is increasing significantly because of their miniaturisation and low power consumption. These devices currently draw power from batteries or chemical fuel cells. Their limited life-spans prompt active research to find an alternative solution by harvesting ambient energy from the environment. Numerous sources are available such as solar, thermoelectric, acoustic, and mechanical vibrations. Among them, mechanical vibration is perhaps the most practical to power these wireless electronic devices via piezoelectric transduction. Three most common piezoelectric materials are Lead zirconate titanate (PZT), zinc oxide (ZnO) and aluminum nitride (AlN). AlN is preferred over ZnO and PZT for several reasons. Chiefly among them is because it has the highest electromechanical coupling along the c-axis of wurzite AlN for longitudinal deformation. This thesis investigates the sputtering of c-axis oriented AlN on top of cubic-silicon carbide-on-silicon (3C-SiC-on-Si) substrates for piezoelectric applications. The 3C-SiC buffer layer was used to reduce the lattice mismatch and thermal expansion coefficient between AlN and Si. In the first part of the research, RF sputtering was utilised for depositing AlN. The low growth rate of RF sputtering prompted the switch to DC sputtering. The DC sputtering suffered from electrical arching problems, which were addressed by gradually decreasing the sputtering pressure. However, the system had the limitation of 1200 W of maximum power.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Engineering
Science, Environment, Engineering and Technology
Full Text
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Fourmentin, Richard. "Modélisation thermodynamique du système Fe-Zn-Al-Cr à 460°C et son impact sur les procédés de galvanisation". Lille 1, 2004. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2004/50376-2004-Fourmentin.pdf.
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En raison de l'utilisation d'équipements en acier inoxydable lors de la galvanisation de tôles automobiles, le chrome se trouve de façon "naturelle" dans les bains de zinc, qui contiennent également de l'aluminium et du fer. L'objectif de cette thèse est de déterminer l'influence du chrome sur les équilibres thermodynamiques entre la phase liquide et les phases solides, en élaborant le diagramme Fe-Zn-Al-Cr à 460ʿC. Une série d'expériences a été menée dans les systèmes ternaires Fe-Zn-Cr et Al-Cr-Zn à 460ʿC. Ces résultats expérimentaux ainsi que le diagramme Fe-Zn-Al à 460ʿC, grâce au logiciel Thermo-Calc ont permis d'obtenir la modélisation du diagramme Fe-Zn-Al-Cr par l'optimisation des paramètres d'interactions entre atomes dans les différentes phases solides et liquide. Ce diagramme quaternaire a été confronté aux résultats de galvanisations et de galvannealing d'aciers IF, afin de proposer un modèle expliquant l'influence de la présence du chrome sur les revêtements obtenus. Ce modèle a également été étendu à des aciers industriels présentant des problèmes de "galvanisabilité".
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Bragantini, Benoît. "Caractérisation structurale et fonctionnelle de la protéine Bcd1, impliquée dans la biogenèse des snoRNP à boîtes C/D chez la levure Saccharomyces cerevisiae". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0295/document.
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La protéine Bcd1 est un facteur nucléaire essentiel à la viabilité cellulaire de la levure Saccharomyces cerevisiae. Il est décrit comme requis pour assurer la stabilité des snoRNA à boîtes C/D. Ces petits ARN non codants s’assemblent à un jeu de 4 protéines invariables pour former les snoRNP à boîtes C/D qui sont des acteurs cruciaux de la biogenèse des ribosomes. En effet, quelques-unes de ces particules participent aux mécanismes assurant la maturation du précurseur des ARN ribosomiques et la grande majorité des autres particules sont des catalyseurs de la modification par 2’-O-méthylation des riboses. Bcd1p n’est pas présente au sein des particules matures, mais fait partie de ses facteurs d’assemblage, au même titre que les sous-complexes Rsa1p:Hit1p et R2TP (Rvb1p:Rvb2p:Tah1p:Pih1p). Notre analyse de différents fragments de Bcd1p a dans un premier temps montré que sa région N-terminale (résidus 1 à 96) suffit à lui conférer son caractère essentiel. Cette région comprend un domaine à double doigt à zinc de la famille zf-HIT, également présent chez un autre facteur d’assemblage des snoRNP à boîtes C/D, la protéine Hit1. Nous avons résolu la structure 3D en solution de ces doigts à zinc et montré que ce sont des modules d’interaction avec les protéines Rvb1/2. Dans un second temps nous avons identifié la région C-terminale (résidus 120 à 303) de la protéine Bcd1 comme étant suffisante pour interagir avec la chaperonne d’histone Rtt106p. La structure 3D en solution de ce domaine a été déterminée par RMN. Différentes approches de cinétique d’échange hydrogène/deutérium et d’expériences de cross-link suivies par des analyses par spectrométrie de masse, des expériences de titrage par RMN et de SAXS nous ont permis d’obtenir des informations sur les surfaces d’interaction de chacune de ces deux protéines. Un fragment, défini à partir des données de RMN de Bcd1p libre, nous a permis d'obtenir des cristaux du complexe Bcd1p:Rtt106p ouvrant la perspective de résoudre sa structure 3D par diffraction aux rayons X. De plus, des études fonctionnelles ont débuté visant à déterminer l’importance de la formation de ce complexe sur la biogenèse des snoRNP à boîtes C/D et l’impact de Bcd1p sur l’interaction entre Rtt106p et les nucléosomesThe protein Bcd1 is a nuclear factor essential for the cellular viability of the yeast Saccharomyces cerevisiae. It is described as required to ensure box C/D snoRNA stability. These small non-coding RNAs associate with an invariable set of 4 proteins to form the box C/D snoRNPs that are crucial players in ribosome biogenesis. Indeed, some of these particles participate in mechanisms for the maturation of the ribosomal RNA precursor (prerRNA) and the vast majority of the other particles are catalysts of 2’-O-methylation of riboses. Bcd1p is not present in mature particles, but is one of the assembly factors in addition to the Rsa1p:Hit1p and R2TP (Rvb1p:Rvb2p:Tah1p:Pih1p) sub-complexes. Our analysis of the different Bcd1p fragments has firstly shown that the essential function of Bcd1p relies on its N-terminal region (residues 1 to 96). It comprises a double zinc finger domain from the zf-HIT family, also present in another box C/D snoRNP assembly factor, the protein Hit1. We solved the 3D solution structure of these two zinc fingers and showed that these are modules for the interaction of Bcd1p with the Rvb1/2 proteins. Secondly, we identified the C-terminal region (residues 120 to 303) of Bcd1p as being sufficient to interact with the histone chaperone Rtt106p. The 3D solution structure of this domain of Bcd1p was determined by NMR. Different approaches of hydrogen/deuterium kinetic exchange and cross-link experiments followed by mass spectrometry analysis, NMR titration, and SAXS allowed us to obtain information about the interaction surfaces on each of the two proteins. A fragment defined from NMR data on the free Bcd1p allowed us to obtain crystals of the Bcd1p:Rtt106p complex, opening the perspective to solve its 3D structure by X-ray diffraction. Furthermore, functional studies started in order to determine the importance of this complex formation in box C/D snoRNP biogenesis and the impact of Bcd1p on the interaction of Rtt106p with nucleosomes
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Garcia, Assuero Faria. "Estudo da estabilidade estrutural de uma proteína recombinante ligante de zinco e cálcio - Calgranulina C (S100A12) porcina". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-30042007-141038/.
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S100A12 porcina é um membro da família das proteínas S100, um grupo de pequenas proteínas ligantes de cálcio caracterizado pela presença de dois motivos EF-hand. Estas proteínas estão envolvidas em diversos eventos celulares, como a regulação da fosforilação protéica, atividade enzimática, tamponamento de Ca+2, processos inflamatórios e a polimerização de filamentos intermediários. Adicionalmente, algumas dessas proteínas podem ligar Zn+2, o qual pode afetar a ligação do íon Ca+2, particularmente para as proteínas S100. Neste trabalho, a seqüência gênica que codifica a proteína S100A12 porcina foi obtida por meio da construção de um gene sintético usando códons preferenciais para E.coli, permitindo a produção recombinante de grandes quantidades da proteína. Um estudo termodinâmico da estabilidade estrutural foi realizado, assim como a interação da proteína recombinante com íons divalentes usando técnicas de dicroísmo circular (CD) e fluorescência extrínseca. A desnaturação e renaturação induzidas por uréia ou temperatura indicam que se trata de um processo reversível e que a ligação dos íons Zn+2 e ou Ca+2 à rS100A12 aumenta sua estabilidade. A interação da sonda ANS com a proteína na presença de seus ligantes expõe superfícies hidrofóbicas podendo assim facilitar sua interação com macromoléculas alvo. Analisados em conjunto, os resultados obtidos indicam que S100A12 porcina é capaz de assumir diferentes conformações as quais podem estar correlacionadas com sua função fisiológica.Porcine S100A12 is a member of S100 family, a small acidic calcium-binding proteins group characterized by the presence of two EF-hand motifs. These proteins are involved in many cellular events as the regulation of protein phosphorylation, enzymatic activity, Ca+2 homeostasis, inflammatory processes and intermediate filament polymerization. In addition, some of these proteins can bind Zn+2, which can affect the binding of Ca+2 particularly to S100 proteins. In this study, the gene sequence encoding S100A12 was obtained by the synthetic gene approach using E. coli codon bias allowing the recombinant production of large amounts of the protein. We report here a thermodynamic study on the structural stability of this recombinant protein and its interaction with divalent ions using circular dichroism and extrinsic fluorescence. The folding/unfolding induced by urea or temperature indicated a reversible process and the binding of Zn+2 or Zn+2 and Ca+2 to S100A12 increasing its stability. The interaction of the ANS probe with the protein in the ligant presence can lead to exposition of hydrofobic regions allowing its interaction with target macromolecules. Taken together, the results indicated that porcine S100A12 may assume different conformations that could be correlated to its physiological function.
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Bernard, David. "Détermination de la structure et de la dynamique du domaine de la protéine MIZ-1 formé des doigts de zinc 5 à 8 par résonance magnétique nucléaire". Mémoire, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6272.
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Miz-1 est un facteur de transcription qui active la transcription de gènes cytostatiques tels que p15[indice supérieur 1NK4B] ou p21[indice supérieur CIP1]. Il s’agit d’une protéine de la famille BTB/POZ, qui possède un ensemble de 13 doigts de zinc de type Cys?His? dans sa portion C-terminale. L’activation de ces gènes par Miz-1 peut être régulée par les protéines SMAD. SMAD3 et 4 peuvent toutes deux se lier aux doigts de zinc 1 à 4 de Miz-1, et les autres doigts de zinc sont pressentis pour être responsables de la liaison à l’ADN. Les séquences reconnues par Miz-1 sur les promoteurs des deux gènes mentionnés ci-haut ont été identifiées, mais n’ont pas d’homologie entre elles. L’oncogène c-Myc a la possibilité de se lier à Miz-1, et cette interaction cause la répression des gènes normalement activés par Miz-1, favorisant ainsi la prolifération cellulaire. Cette interaction cruciale, de même que celle entre Miz-1 et l'ADN, est toutefois assez mal caractérisée. Le but du projet dont fait partie ce mémoire est d’éclaircir tout ce mécanisme de liaison. Ce mémoire étudie la structure et les propriétés dynamiques des doigts de zinc 5 à 8 de Miz-1, qui, selon l’hypothèse initiale, seraient impliqués dans la liaison au promoteur des gènes-cibles de Miz-1. La résonance magnétique nucléaire est la technique qui a été utilisée dans le but d’obtenir ces résultats, et une partie importante de ce mémoire est dévouée à la théorie derrière cette puissante technique. La détermination de la structure de ces doigts de zinc est en fait une seule des nombreuses étapes du projet de l’élucidation du mécanisme de transrépression par c-Myc/Miz-1. Suite à la présentation des structures de ces doigts de zinc, ce mémoire s’intéresse à leurs caractéristiques dynamiques très particulières pour ce type de domaine protéique. Nous avons en effet découvert que les doigts de zinc 5 à 8 présentaient un niveau très élevé d’échange conformationnel, et qu’une portion du doigt de zinc 6 ne peut être caractérisée structurellement à cause de mouvements dans l’échelle de la micro/milliseconde, eux-mêmes dus à des répulsions électrostatiques. En conclusion, nous proposons que le ZF 6 ait un rôle de charnière entre deux ensembles de ZFs dans Miz-1. Ces résultats permettent l’actualisation du modèle de liaison de Miz-1 au promoteur de p15[indice supérieur INK4B] qui avait été élaboré comme hypothèse, et ils nous rapprochent de la compréhension de la transrépression par c-Myc. [symboles non conformes]
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Bouregaya, Souad. "Synthèse d'un ciment alitique à moindre impact environnemental à partir de vase de barrage et utilisant le sulfate de zinc comme minéralisateur". Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0026/document.
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L’objectif de cette étude est de réaliser la synthèse d’un ciment riche en phases réactives, obtenu par cuisson à une température inférieure ou égale à 1300°C d’un cru constitué de vase de barrage et d’un complément de chaux et utilisant du sulfate de zinc comme minéralisateur. Cette étude donne les caractéristiques minéralogiques et les propriétés physico- mécaniques du ciment synthétisé. L’analyse qualitative et quantitative par diffraction des rayons X a été utilisée pour caractériser les matériaux bruts et les minéraux du ciment. L’évolution du durcissement des pâtes de ce ciment a été suivie et quantifiée par calorimétrie isotherme, DTG, diffraction des rayons X et au moyen d’essais mécaniques en compression sur éprouvettes de pâte pure. Les résistances obtenues à 7 et 28 jours permettent de viser une classification CEM II 32,5 NThe objective of this study is the synthesis of a cement rich in reactive phases, obtained by burning, at a temperature lower than or equal to 1300 °C, a raw material composed of sludge from a dam with a complement of lime, and using zinc sulphate as a mineralizer. This study gives the mineralogical, physical and mechanical characteristics and properties of the synthesized cement. Qualitative and quantitative X-ray diffraction analysis was used to characterize the raw materials and the minerals of the cement. The evolution of its hardening was monitored and quantified by isothermal calorimetry, DTG, X-ray diffraction and mechanical compression tests on pure paste samples. The strengths obtained at 7 and 28 days make it possible to aim at a CEM II 32.5 N classification
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Латишев, Віталій Михайлович, Виталий Михайлович Латышев i Vitalii Mykhailovych Latyshev. "Механизмы роста 3D-структур C, Cu, Zn в условиях околоравновесной стационарной конденсации". Thesis, СумГУ, 2015. http://essuir.sumdu.edu.ua/handle/123456789/39759.
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Дисертаційна робота присвячена вивченню закономірностей структуроутворення 3D-систем C, Cu і Zn за умов конденсації слабопересичених парів і при використанні як класичного методу магнетронного розпилення, так і накопичувальної системи плазма-конденсат (НСПК). При використанні НСПК установлені технологічні умови формування на основі вуглецю наносфер і мікросфер, на яких у подальшому зароджуються нановолокна. Створено математичну модель, яка адекватно описує процес дозрівання за Оствальдом приблизно однакових за розміром кулястих острівців міді. На прикладі трьох серій експериментів з осадження пористих структур міді за допомогою магнетронного розпилення було показано, що основу формування пористих систем становлять малі значення пересичення осаджуваних парів, що тягнуть за собою різні швидкості нарощування конденсату в близько розміщених точках ростової поверхні. Вивчені механізми структуроутворення 3D-систем цинку при використанні як класичного методу магнетронного розпилення, так і НСПК. Установлено, що окиснені пористі конденсати цинку можуть бути використані як газові сенсори.Диссертационная работа посвящена изучению закономерностей структурообразования 3D-систем веществ существенно различной летучести (C, Cu и Zn) в условиях околоравновесной стационарной конденсации. Осаждая конденсаты углерода в условиях, близких к термодинамическому равновесию, с помощью накопительной системы плазма-конденсат (НСПК), на начальном этапе селективного роста (в течение 6 мин) при давлении аргона 6 Па и мощности разряда 50 Вт были получены шарообразные слабосвязанные графитоподобные наноструктуры. При более продолжительной конденсации в течении нескольких часов происходит формирование графитоподобных шарообразных включений. Повышение давления рабочего газа от 6 до 10 Па при слабом изменении всех прочих технологических параметров способствует реализации более стационарного технологического процесса и зарождению на графитоподобных шарообразных включениях нановолокон. Сделано предположение о том, что в качестве активных центров зарождения углеродных нановолокон выступают изогнутые графеновые плоскости шаровидных структур. Установлено, что процесс зарождения и роста различных нановолокон разнесен во времени и определяется наличием шарообразных графитоподобных включений. Создана математическая модель массопереноса распыленного вещества в промежутке между мишенью и подложкой, адекватно описывающая процесс созревания по Оствальду островков меди приблизительно одинакового размера. На примере трех серий экспериментов по осаждению пористых структур меди при помощи магнетронного распыления было показано, что основу процесса образования пор составляют малые значения пересыщения осаждаемых паров, влекущие за собой различные скорости наращивания конденсата в близлежащих точках ростовой поверхности. Подобный селективный рост кристаллов возможен вследствие флуктуаций в распределении активных центров, при избирательной застройке кристаллографических плоскостей с максимальной энергией десорбции адатомов, а также при наличии отрицательного смещения и соответствующей фокусировке осаждаемых ионов на выступающие части ростовой поверхности. В последующем неполное сращивание кристаллов приводит к образованию пор и к появлению активных центров, необходимых для зарождения новых кристаллов. На основании анализа экспериментальных данных по получению конденсатов цинка в НСПК было выявлено существование трех зон (на диаграмме параметров «давление рабочего газа – мощность разряда») в пределах которых формируются одинаковые по характеру пористые структуры. Широкий спектр значений технологических параметров зоны 1 подтверждает процесс самоорганизации малых значений пересыщений и позволяет получать наносистемы цинка с высокой воспроизводимостью структурно-морфологических характеристик при среднем диаметре нанонитей 60 нм. При переходе в зону 2, а затем в зону 3 наблюдается постепенное увеличение пересыщения, которое подтверждается постепенным переходом к формированию структур в виде слабо связанных друг с другом системы ограненных кристаллов. Показано, что сопротивление окисленных систем цинка сильно зависит от газовой среды, в которой они находятся. Так для концентрации 0,7% пропана в воздухе, сопротивление образца снижается в 159 раз по сравнению с сопротивлением в чистом воздухе. Таким образом, полученные структуры могут найти применение в качестве газовых сенсоров, по крайней мере, к смеси пропан-бутан.
Dissertation is devoted to the investigation of the structure formation regularities of the C, Cu and Zn 3D-systems under the condensation conditions of the weakly saturated vapors and by using both the classical method of magnetron sputtering and the plasma-condensate accumulation system (PCAS). Technological conditions of the nanospheres and microspheres formation on the basis of C, on which hereafter the nanowires arise, are determined. A mathematical model that adequately describes the process of Ostwald ripening of the rounded Cu islands of the approximately equal size was created. On the example of three series of experiments on Cu porous structures deposition by using magnetron sputtering it has been shown that the small values of supersaturation of the deposited vapors, which cause different speeds of the condensate’s increase in the nearby situated growth surface points constitute the basis of the porous structures formation. Mechanisms of Zn 3D-systems structure formation by using both classical method of magnetron sputtering and PCAS are studied. It is determined that the oxidized porous zinc condensates can be used as gas sensors.
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ALLVAR, MARIE. "MIG/MAG brazing with Cold Metal Transfer". Thesis, KTH, Maskinkonstruktion (Inst.), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-148077.
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In the automotive industry a commonly used material is thin steel sheets coated with a thin layer of zinc for corrosion resistance purposes. Welding of this material, with the high temperatures involved, causes problems with zinc burn-off leading to reduced corrosion resistance. The zinc evaporation also causes arc disturbances leading to spatter formation, pores and difficulties achieving good visual weld quality. The joints are in many cases visible or semi-visible (e.g. visible after opening a door) and “A-grade” quality is demanded, meaning no visible discontinuities are allowed. It also implies a smooth and generally appealing appearance of the joint.An alternative to welding is brazing, and laser brazing meets the requirements but the process is associated with high costs. In the national project “LEX-B”, funded by Vinnova, the possibilities of using arc brazing, in particular one MIG/MAG brazing and two TIG brazing processes, for some automotive applications are investigated. This master thesis is connected to the first part of the project and aims at compiling data for making a selection of the most promising process to investigate and optimise further. LEX-B is conducted in cooperation between Swerea KIMAB, Volvo Trucks, Scania CV and University West. The joint of interest is a lap joint between bottom and upper sheets of 1.2 mm and 0.8 mm respectively that represents a joint on the side of a truck cabin. The requirements are visual A-grade quality and tensile shear strength of 300 MPa.In the project the MIG/MAG process Cold Metal Transfer (CMT) was compared to the TIG processes forceTIG and Plasmatron. CMT was experimentally investigated while the results for the other two processes were obtained partly from a previous study and partly from Volvo Trucks where tests were performed simultaneously. A system for measuring data for the process was developed, test specimens were brazed and examined visually and mechanical destructive testing was performed to ensure the tensile shear strength. Parameter studies were done for further process optimisation.Inom fordonsindustrin är ett ofta använt material stål i tunna ark belagda med zink p.g.a. zinkets korrossionsskyddande egenskaper. Vid svetsning av detta material uppstår problem med zink som förångas vilket leder till minskad korrosionsbeständighet. Förångningen av zink orsakar också störningar av ljusbågen vilket leder till sprut, porer och svårighet att uppnå god visuell svetskvalitet. Fogarna är i många fall synliga eller delvis synliga (t.ex. synlig efter att ha öppnat en dörr) och "A-kvalitet" efterfrågas, vilket innebär att inga synliga diskontinuiteter tillåts. Fogen ska upplevas jämn och tilltalande.Lödning är ett alternativ till svetsning, och laserlödning är en process som uppfyller kraven men är förknippad med höga kostnader. I det nationella projektet "LEX-B", som finansieras av Vinnova, undersöks möjligheterna att använda båglödning, specifikt en MIG/MAG-process och två TIG-processer, för dessa applikationer. Detta examensarbete är anslutet till den första delen av projektet och syftar till ta fram underlag för att välja den mest lovande av dessa processer för vidare utredning och optimering. LEX-B sker i samarbete mellan Swerea KIMAB, Volvo Lastvagnar, Scania CV och Högskolan Väst. Den undersökta fogen är en överlappsfog mellan en undre plåt med 1,2 mm tjocklek och en övre plåt med 0,8 mm tjocklek. Detta representerar en fog på sidan av en lastbilshytt. Kraven är visuell A-kvalitet och en drag-skjuvhållfasthet av 300 MPa.I projektet jämfördes MIG/MAG-processen Cold Metal Transfer (CMT) med TIG-processerna forceTIG och Plasmatron. CMT testades experimentellt medan resultaten för de övriga två processerna erhölls dels från tidigare tester och dels från Volvo Lastvagnar där tester utfördes parallellt. Ett mätsystem for att dokumentera processdata utvecklades och de framställda lödfogarna undersöktes visuellt och med mekanisk förstörande provning för att säkerställa drag-skjuvhållfastheten. Parameterstudier gjordes för vidare optimering av processen.
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Ye, Syun-Long, i 葉勳隆. "Magneto-Optical Property of Cobalt-Coated Zinc Oxide Nanorods". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/5wp8wk.
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碩士國立屏東大學
應用物理系碩士班
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ZnO has attracted a lot of research interests and become a popular material in last decades because of its unique electrical、optical、chemical and piezoelectricity characteristic. In addition, transition metal (TM) doped ZnO has also been considered as a potentials for realized magnetic semiconductor for spintronics application. However, whether coating a TM on semiconductor nanostructures can make them ferromagnetic by interfacial charge transfer is also worthy of investigation. In this work, the room-temperature ferromagnetic ZnO spin-polarized semiconductor band can be achieved by Co coating. Energy-dependent magnetic circular dichroism (MCD) and spectra, from which the difference between the absorptions of left and right circularly polarized light at particular energies can be determined, provide valuable information about the spin-polarized DOSs and their influence on the magnetic properties, helping to determine the origin of the ferromagnetism of the semiconductor. We expect such kind of hybrid magnetic nanostructures may be useful for opto-spintrionics application.