Dissertations / Theses on the topic 'Ioni zinco'

Les electrodepositions sur une electrode de zinc sont realisees dans une solution de koh, a la fois en courant continu et en courant pulse. La compacite des depots est mesuree au moyen d'un compacimetre. Il est montre qu'avec un courant direct, la densite du courant doit etre ajustee en fonction de la concentration en zno pour eviter les depots spongieux

The modification of single crystal epitaxial ZnO thin films grown by Pulsed Laser Deposition on c-axis oriented sapphire substrates by Ion Beam Processing was investigated. Nitrogen doping of the films was attempted using nuclear transmutation using the ¹⁶O (³He, ⁴He) ¹⁵O reaction at 6.6 MeV. The ¹⁵O product is unstable and decays to ¹⁵N after several minutes by positron emission. There are several potential advantages to using nuclear transmutation including producing nitrogen atoms on the correct lattice site for doping and reduced crystal damage as compared to conventional ion beam implantation. In the experiments in this thesis the doping levels achieved ~10¹⁴ cm^-3 were too low to be expected to dope the films to p-type. However several beneficial effects due to the ion beam processing were observed, including large increases in resistivity, reduction of defect luminescence, and substantial increases in the response of photoconductive detectors. In addition to desired effects in some films it was also found that in some films bubble like structures approximately 10 ìm in diameter were formed where the thin film delaminated from the surface. It was assumed that mechanism for the bubble formation was the build up of helium gas at the sapphire/ZnO interface.

The industrial revolutions in the past centuries have led to extraordinary changes in social life, transportation, and production activities, with energy utilization reflecting the progress of industrial technology and human civilization. The primary energy sources that have been used to power all tech-dependent human activities are fossil fuels, such as crude oil and natural gas, with no little consequences. In fact, pollution arising from fossil fuel combustion has had a devastating impact on the natural environment and on human health. In addition, the natural reserves of fossil fuels are limited. Therefore, these energy sources are not sustainable from multiple points of view. Hence, the focus of research has shifted to environmentally benign sustainable energy. The development of renewable energies and the need for means of transport with reduced CO2 emissions have generated new interest in storage, which has become a key component of sustainable development. As electrochemical storage systems, there are many different types of batteries and most of them are subject to further research and development. Recently, several battery technologies, such as redox flow, sodium sulfur, lead carbon, or lithium ion, have been proposed as possible systems for large-scale stationary energy storage, but they suffer from low charging rates, high operating temperatures and the use of hazardous materials in their components and/or high costs. These drawbacks limit their integration into the electrical power grid. Metal-ion aqueous rechargeable batteries have become a low-cost, safe, and environmentally friendly alternative to traditional technologies. Several cells based on lithium intercalation electrodes have been developed in recent years. However, the lower energy density and the scares availability of the lithium brought to the necessity for energy storage systems based on alternative elements. A new family of open-framework materials with the Prussian Blue crystal structure have been recently studied as materials for positive electrodes in potassium-ion batteries, showing excellent specific charge retention and rate capability. Over the last years, aqueous Zn-ion batteries (ZIBs) have brought great interest due to their applicability as cheap and environmentally friendly energy storage devices for power grid applications. Among the potential active materials, which can be used in this type of battery, open framework Prussian Blue (PB) and its analogues (PBAs) have attracted the attention of the researchers thanks to their excellent properties. Because of the large interstitial sites, PBAs facilitate the reversible intercalation of hydrated ions from an aqueous electrolyte. Belonging to the Prussian blue analogues (PBAs) family, copper hexacyanoferrate (CuHCF) has been shown to be a promising candidate as positive electrode material for aqueous ZIBs. In addition, CuHCF can be synthesized through a simple synthesis. Despite CuHCF can be produced through an easy co-precipitation route, the synthesis of the desired phase is not straightforward to control. Such complications in controlling the synthesis’ reaction mechanism have been evaluated in previous studies. The measurements carried out with zinc as the reference electrode differ in terms of life cycle from the measurements made with Ag / AgCl as RE. These results led to the consideration that the potassium chloride solution of the reference electrode somehow plays a role in the life span of the electrode due to potential losses of the solution in the electrolyte. For this reason, it was decided to further evaluate the role of the electrolyte. Therefore, the purpose of this thesis is to investigate the effect of the presence of potassium chloride as an electrolyte in the co-presence of zinc sulfate. Furthermore, the effect of an excess of potassium ions in the synthesis of the material was also evaluated.

Conselho Nacional de Desenvolvimento Científico e Tecnológico
The main objective of this work was to study the individual and simultaneous incorporation of Zn2+ and Ag+ ions and their effects on physical-chemical characteristics of the hydroxyapatite (HA) for their application in bone tissue engineering. The chemical analyses confirmed the presence of 0.10% of Zn2+ and 0.13% of Ag+ (relatively to the quantity of Ca2+ ions). The insertion of the metal ions into HA did not cause significant modifications in the crystallinity index compared to pure HA. In the same way, no phase transformation was verified after insertion. No effect was noticed on the lattice parameters after the insertion of Zn2+ comparatively to those calculated to the pure HA. Conversely, the insertion of Ag+ induced a remarkable contraction of the unit cell volume. The thermal treatment strongly increased the crystallite growth for all samples, and also promoted the change from stretched crystals before calcination to spherical ones after calcination. The immersion of the specimens in the simulated body fluid (SBF) allowed the incorporation of carbonate into the HA structure, causing a significant reduction in the crystallite size, accompanied by a stretched and crystallinity index.
O principal objetivo desse trabalho foi estudar a incorporação individual e simultânea dos íons Zn2+ e Ag+ e seus efeitos sobre as características físico-químicas da hidroxiapatita (HA) visando sua aplicação na engenharia tecidual óssea. Análises químicas confirmaram a presença de 0,10% de Zn2+ e 0,13% de Ag+ (em relação à quantidade de Ca2+ presente). A síntese da HA enriquecida com os metais não causou modificações significativas do índice de cristalinidade em relação a HA pura e nem induziu a transformação de fases das amostras, após calcinação. O Zn2+ não afetou de forma significativa os parâmetros de rede em relação àqueles calculados para a HA pura. Já a entrada do Ag+ produziu uma grande contração da célula unitária. Com relação ao alongamento do cristal, foi possível observar que após a calcinação houve uma tendência dos cristais em adquirir formas mais esféricas. A imersão das amostras em solução simuladora do plasma sanguíneo (SBF) proporcionou a entrada de carbonato na HA, provocando ainda uma redução significativa do tamanho dos cristalitos, acompanhada de uma diminuição no alongamento e no índice de cristalinidade em relação aquelas que não entraram em contato com a solução.

La fixation du substrat ou celle du phosphate sur la phosphatase alcaline intestinale de boeuf produit un faible changement de structure ssecondaire, suggérant une fixation élastique du substrat et un fonctionnement idéal de l'enzyme. Bien que les sensibilités des apoenzymes de mammifère et d'E. Coli à l'égard es ions (Zn²+, Mg²+) soient demeurées semblables, leur cinétiques de récupération d'activité et les changements de structures secondaires évoluent d'une manière distincte, indiquant certaines différences au niveau de leurs sites actifs. Tout en hydrolysant l'inhibieur de la minéralisation, le pyrophosphate (PPi), la phosphatase alcaline possède une activité de phosphodiestérase, hydrolysant l'ATP pour former du PPi. Les mécanismes de régulation de PPi dans l'environnement extracellulaire du tissu osseux nécessitent une réévaluation

Ce travail est consacre a l'etude de la luminescence des ions de terre rare trivalents inseres dans l'oxyde de zinc polycristallin. Les etudes structurales de nos echantillons ont montre que la terre rare est localisee en surface des grains d'oxyde de zinc ainsi qu'aux joints de grains. La clarification du mecanisme de l'electroluminescence des terres rares inseres dans l'oxyde de zinc a ete effectuee pour deux dispositifs electroluminescents: le premier base sur une jonction semi-conducteur/electrolyte, le second equivalent a une varistance etant entierement solide. L'excitation des terres rares s'opere par impact direct d'electrons chauds ; ces electrons chauds sont generees, soit par avalanche dans la region de claquage du semi-conducteur pour le premier dispositif electroluminescent (cellule electrochimique), soit par emission thermoionique aux joints de grains dans la region de preclaquage pour le second dispositif (varistance). Les mesures d'electroluminescence associees a des mesures de photoluminescence ont constitue un bon moyen pour attribuer des raies d'emission des ions trivalents de terres rares. Enfin, les mesures d'electroluminescence ont permis une evaluation approximative de la taille moyenne des grains d'oxyde de zinc

A number of symmetric porphyrins containing both zinc(II) and lead(II) central metal ions have been prepared. Several routes to these compounds have been investigated and their merits evaluated. The conjugation of the chromophores has been extended by the inclusion of different trans- substituted arylethynyl substituents in the meso-position. An improved multigram method for the preparation of [bis-trimethylsilyethynylporphinato]zinc(II), which does not necessitate chromatographic purification, is described. The use of [5-triisopropylsilylethynylporphinato]zinc(II) for the preparation of donor/acceptor prophyrins via Sonogashira coupling, several of which were prepared, is also described. Investigations of the binding of 4(3H)pyrimidone with [5,5'-bis-[10,20-bis(3,5-di-tert-butylphenyl)-15-tri-iso-propylsilylethynyl-porphinyl]-1,3-butyn-1,4-diyl]dizinc(II) were made. The association constant was found to be 2500 ± 140 mol^-1 (ΔG = -4.6 Kcal/mol), significantly greater than that for 4(3H)pyrimidone alone (444 ± 5 mol^-1), as determined by NMR dilution experiments. The crystal structures of [5,15-bis(3,5-bis-tert-butylphenyl)porphinato]zinc(II), [5,15-bis-(3,5-di-tert-butylphenyl)-10,20-bis-triisopropylsilylethynylporphinato]lead(II), [5,10,15,20-tetrakis-triisopropylsilylethynylporphinato]lead(II), 5,15-bis-(3,5-bis-tert-butylphenyl)-10,20-bis-phenylethynylporphyrin, [5,15-bis-(3,5-bis-tert-butylphenyl)-10,20-bis-(3-hydroxy-3-methyl-butynyl)porphinato]zinc(II),5,10,15,20-tetrakis-triisopropylsilylethynylporphyrin and [5,15-bis-(3,5-bis-tert-butylphenyl)-10-(4-N, N-dimethylaminophenylethynyl)-20-triisopropylsilylethynylporphinato]zinc(II) are also described.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
O cromato à amplamente utilizado como inibidor de corrosÃo. No entanto, à altamente tÃxico e carcinogÃnico, o que tem levado pesquisadores a buscarem alternativas ecologicamente amigÃveis a este inibidor. Dentre estes, molibdato, tungstato, silicato e fosfato surgem como potenciais candidatos por apresentarem propriedades inibidoras e serem atÃxicos. Assim, este trabalho tem por objetivo desenvolver um estudo sistemÃtico dos Ãons como inibidores da corrosÃo do Zn. Foram utilizadas soluÃÃes aquosas de NaCl 10-1 mol dm-3 com concentraÃÃes dos inibidores variando de 10-4 a 10-1 mol dm-3 . A eficiÃncia destes com relaÃÃo à corrosÃo do Zn foi avaliada empregando-se medidas do potencial a circuito aberto, curvas de polarizaÃÃo potenciodinÃmica e espectroscopia de impedÃncia eletroquÃmica. As tÃcnicas de Microscopia EletrÃnica de Varredura (MEV), Energia Dispersiva de Raios-X (EDX), DifraÃÃo de Raios-X (DRX) e Espectroscopia FotoeletrÃnica de Raios-X (XPS) foram usadas para caracterizar o Zn apÃs os ensaios de corrosÃo. Todos os Ãnions estudados inibiram a corrosÃo do Zn. Com as tÃcnicas de caracterizaÃÃo foi possÃvel identificar a presenÃa de filmes superficiais de silicato, tungstato, molibdato e fosfato na superfÃcie do Zn apÃs os ensaios de corrosÃo nas respectivas soluÃÃes contendo os inibidores
The chromate is widely used as a corrosion inhibitor. However, it is highly toxic and carcinogenic, which has done researchers to study environmentally friendly alternatives to this inhibitor. Among these, molybdate, tungstate, silicate and phosphate anions appear as potential candidates because they are non toxic. Thus, this work aims to develop a systematic study to investigate molybdate, tungstate, silicate and phosphate as corrosion inhibitors of zinc. Aqueous solutions of 10-1 mol dm-3 NaCl were used and the concentrations of the inhibitors ranging from 10-4 to 10-1 mol dm-3. The corrosion studies were carried out by open circuit potential measurements, potentiodynamic linear polarization and electrochemical impedance spectroscopy. The Scanning Electron Microscopy (SEM), X-Ray Dispersive Energy (XDE), X-Ray diffraction (XRD) and X-Ray Photoelectronic Spectroscopy (XPS) techniques were used to characterize the Zn after the corrosion tests. All the studied anions inhibited the zinc corrosion. The characterization techniques made possible to detect the presence of molybdate, silicate, tungstate and phosphate on the zn surface after the corrosion tests in the solution containing the corresponding inhibitors

The adsorption of zinc ions as a function of pH and total dissolved metal concentration was experimentally investigated for three types of clays (kaolinite. montmonllonite. and Londonderry). The results indicate increases in adsorption of the zinc ions occurs with increases in pH for each of the three clays. Langmuir and Freundlich isotherms were created for each of the clay types.

Orientador: Sonia Maria Alves Bueno
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-25T09:14:39Z (GMT). No. of bitstreams: 1 Mourao_CeciliaAlves_M.pdf: 2559584 bytes, checksum: efe6b17b9b7e5ceb16ade74a6ae30629 (MD5) Previous issue date: 2014
Resumo: As imunoglobulinas G (IgG) e seus fragmentos Fab, F(ab)¿2 e Fv apresentam aplicações proeminentes nas áreas terapêuticas e de diagnósticos. Em determinadas situações em que a região Fc é dispensável e/ou deletéria, emprega-se preferencialmente fragmentos em relação à IgG não clivada. Tais aplicações requerem um elevado grau de pureza dessas biomoléculas. O elevado custo de obtenção de fragmentos pelas técnicas convencionais justifica a investigação de outras que possam proporcionar a obtenção dessas proteínas, combinando um menor custo com um elevado grau de pureza. Neste sentido, o objetivo deste trabalho foi avaliar e comparar a eficácia dos adsorventes agarose-CM-Asp-Ni(II), agarose-CM-Asp-Co(II), agarose-CM-Asp-Cu(II) e agarose-CM-Asp-Zn(II) na purificação dos fragmentos Fab de IgG humana policlonal, a partir de uma solução de IgG clivada pela enzima papaína. O efeito do sistema tamponante, do íon metálico e do cloreto de sódio foram avaliados. A seletividade das condições cromatográficas foi avaliada por eletroforese SDS-PAGE, Western Blotting e imunodifusão radial. Os resultados indicaram que nas cromatografias conduzidas com o quelato CM-Asp-Co(II) com Hepes e Tris-HCl, na ausência de sal, os fragmentos Fab foram obtidos separados do Fc nas frações de eluição. Nas cromatografias em CM-Asp-Ni(II) com Hepes e fosfato de sódio na presença de NaCl e em CM-Asp-Cu(II) com Tris-HCl e fosfato de sódio na presença de NaCl, a biomolécula alvo foi obtida seletivamente nas frações não retidas (cromatografia negativa). Nas cromatografias em CM-Asp-Zn(II) não houve a recuperação seletiva dos fragmentos Fab. Os resultados das curvas de ruptura com os quelatos CM-Asp-Ni(II), CM-Asp-Co(II) e CM-Asp-Cu(II) revelaram a recuperação de 3,4 mg, 17,1 mg e 8,6 mg de Fab, respectivamente. Os fragmentos Fab foram obtidos com pureza superior a 90%, sendo que para o ligante CM-Asp-Cu(II), segundo o western blot, os fragmentos Fab foram separados da IgG não clivada. Os resultados obtidos nas condições cromatográficas estudadas evidenciam a potencialidade do emprego dos quelatos CM-Asp-Ni(II), CM-Asp-Co(II) e CM-Asp-Cu(II), imobilizados em agarose, para purificação de fragmentos Fab obtidos da clivagem enzimática da IgG humana policlonal
Abstract: Immunoglobulins G (IgG) and their fragments Fab, F(ab)¿2 and Fv are prominently applied as therapeutic and diagnostic tool. Fragments are preferably used rather than the uncleaved IgG, specially when the Fc portion is dispensable or prejudicial. For the mentioned applications, high purity preparations are required. The high costs associated with the conventional downstream processing of these biomolecules is the driving force to investigate purification techniques that can combine lower cost with high purification factor. Therefore, the goal of this work is to evaluate and compare the efficiency of CM-Asp-Ni(II), CM-Asp-Co(II), CM-Asp-Cu(II) and CM-Asp-Zn(II) adsorbents in the purification of Fab fragments from papain-digested human IgG. The effects of buffers, metal-ion and NaCl addition were also studied. The adsorbent/buffer selectivity towards the targeted molecule was evaluated by SDS-PAGE, Western Blotting and radial immunodiffusion assays. Chromatography with CM-Asp-Co(II) as chelated using Hepes and Tris-HCl buffers resulted in Fab recovery in the elution fractions. Whereas the chromatography with CM-Asp-Ni(II) and CM-Asp-Cu(II) both as chelated using Hepes sodium phosphate buffers with NaCl addition resulted in Fab selective recovery in non-retained fractions (negative chromatography). The adsorbent CM-Asp-Zn(II) did not show Fab selective recovery. Breakthrough curves experiments with CM-Asp-Ni(II), CM-Asp-Co(II) e CM-Asp-Cu(II) showed recovery of 3.4 mg, 17.1 mg and 8.6 mg of Fab, respectively. Fab fragments were recovered with purity higher than 90%. When chelated CM-Asp-Cu(II) was use as ligand, Fab fragments were recovery separated from intact IgG as shown in western blot. Results obtained in the chromatographic conditions studied showed the potential use of CM-Asp-Ni(II), CM-Asp-Co(II) and CM-Asp-Cu(II) immobilized in agarose for the purification of Fab fragments from cleaved human polyclonal IgG
Mestrado
Desenvolvimento de Processos Biotecnologicos
Mestra em Engenharia Química

The ditopic ligand, L1, contains both a bipyridine domain and a tetra-azacrown binding domain. Introduction of one equivalent of Cu2+ ions results in co-ordination of the ion by all four of the available N-donor atoms in the azacrown unit. However, introduction of further Cu2+ ions results in the formation of a variety of species depending on the ratio of Cu2+ ions to ditopic ligands available. The bipyridine site is capable of behaving as a bidentate chelator as co-ordination at the bipyridine unit by a further Cu2+ ion allosterically alters the behavior of the azacrown domain. The co-ordination of a Cu2+ ion at the bipyridine unit causes the unit to adopt a planar conformation, preventing all four available N-donor atoms in the tetra-azacrown from co-ordinating an encapsulated copper ion. Therefore coordination of the bipyridine domain changes the tetra-azacrown unit from a tetradentate to a tridentate N-donor unit. A diamino-functionalised cryptate, L2, was synthesized, which is capable of reacting irreversibly with butanal in aqueous media, when in the presence of an excess of metal ions. Co-ordination of the cryptate unit is required in order for the cyclisation to occur, excess metal ions act as Lewis acids in order to promote the reaction, and also co-ordinate the cryptate ion. Co-ordination of the cryptate ion forces the bipyridine unit into a more planar position, allowing the amine groups to move into closer proximity to each other. Subsequent reaction with butanal induces the ligand to form a cyclised bis-aminal complex, as the amino groups react readily with the aldehyde to form a seven-membered bis-aminal species. The cyclised ligand was found to display metal dependent luminescent properties, with zinc ions producing the most intense increase in emissive properties by a significant margin as well as increasing the luminescent lifetime. A potentially hexadentate ligand, L3, was synthesized, which upon co-ordination with dicationic metal ions forms dinuclear double stranded helicate species. The ligand partitions into two separate tridentate binding domains, consisting of two N-donor atoms from a pyridyl-triazole unit and an O-donor atom from a carbonyl oxygen group on the coumarin unit. The ligand contains two coumarin fluorophores, and the luminescent properties of the dinuclear helicate complexes were investigated. It was found that upon co-ordination of Zn2+ the emissive properties were enhanced in comparison with the parent ligand, however introduction of Co2+, Cu2+, Cd2+ and Hg2+ ions induced fluorescent quenching of varying degrees.

The role of metal ions as catalysts for numerous biochemical reactions has been the subject of many investigations. One of the most important classes of ligands are phosphate esters. In this thesis I describe the investigation of some phosphate ester-metal ion equilibria. Formation constants for the complexation of p-nitrophenyl phosphate, phenyl phosphate, 1-naphthyl phosphate, α-D-glucose-1'-phosphate, glycerol-2-phosphate, methyl phosphate, 8-quinolyl phosphate, 8-quinolyl methyl phosphate, triphosphate and fluorotriphosphate with protons, copper, zinc and calcium ions were determined by potentiometry. In addition, the complexation of 1-naphthyl phosphate, 8-quinolyl phosphate and 8-quinolyl methyl phosphate with nickel and cobalt ions was also studied. Protonation enthalpies and copper complexation enthalpies of p-nitrophenyl phosphate, phenyl phosphate, 1-naphthyl phosphate, α-D-glucose-1'-phosphate, glycerol-2-phosphate and methyl phosphate were determined by calorimetry. A correlation between the nucleophilicity of the ester group and the magnitude of the stability constants of the proton, copper and zinc complexes of p-nitrophenyl phosphate, phenyl phosphate, 1-naphthyl phosphate, α-D-glucose-1'-phosphate, glycerol-2-phosphate and methyl phosphate is found and explained in terms of electronic induction effects, i.e. by polarisation of the phosphate oxygens by the ester group. The calorimetric results show that the desolvation of ligand and metal ion during the complexation plays an important role. The possibility of similar correlations for complexes of triphosphates is also discussed.

Potassium ion channels play a key role in the generation and propagation of action potentials. The S4-S5 linker peptide (L45) is believed to be responsible for the anesthetic/alcohol response of voltage-gated K+ channels. We investigated this region to define the structural basis of 1-alkanol binding site in dShaw2 K+ channel. L45 peptides derived from dShaw2 and hKv3.4 K+ channel, which, if part of the complete channel, demonstrate different sensitivity to 1-alcohols. Specifically, dShaw2 is alcohol sensitive and hKv3.4 is alcohol resistant. Structural analysis of L45 with NMR and CD suggested a direct correlation between alpha-helicity and the inhibition of dShaw2 channel by 1-butanol. We used CD and NMR to determine the structure of L45 peptides in micelles and vesicles. We measured spin-lattice relaxation time (T1) and determined the location and surface accessibility of L45 in micelles. These experiments confirm that L45 of dShaw2 adopts an α-helical conformation, partially buried in the membrane and parallel to the surface. The binding and accumulation of rev proteins to an internal loop of RRE (rev responsive element) of unspliced mRNA precursors is a key step of propagation of human immunodeficiency (HIV) virus. Molecules that interfere with this process can be expected to show anti-HIV activity. Our work is based on an assumption that zinc fingers could compete with rev proteins, therefore impeding the life cycle of HIV and stopping its infection. We studied the influence of different cations, anions, and the concentration of salts and osmolytes on the binding affinity with Polyacrylamide Gel Electrophoresis (PAGE) and Isothermal Titration Calorimetry (ITC). We conclude that the types of anions and/or cations and their concentrations affect the enthalpy and entropy of the binding interacitons. Using a gel assay, we confirm that there are three products in RNA-Protein reaction, and both EDTA and salts (and their concentrations) in the gel or samples interfere with RNA-protein complex mobility.

Le développement de nouvelles sources laser solides, compactes, émettant dans le moyen-infrarouge (MIR) a initié l'étude des matrices II-VI dopées aux ions de transitions métallique TM. Parmi ces composés, l'ion chrome inséré dans la matrice anse ressort comme un candidat idéal pour obtenir une émission radiative à température ambiante dans le domaine spectrale du 2-3 mM. Cette thèse s'inscrit dans le cadre de développement de telles sources et plus particulièrement, elle s'intéresse dans l'étude et la réalisation de source laser, accordable, à température ambiante, pour le MIR à partir de matériau Cr2+ : ZnSe polycristallin. L'intérêt des matériaux polycristallins réside sur le coût de fabrication et les dimensions réalisables comparativement aux matériaux monocristallins. Nous avons donc élaboré des matériaux Cr2+ : ZnSe par la méthode de diffusion thermique à partir de substrats de ZnSe mono et poly-cristallin. Dans le but d'obtenir un matériau approprié à l'émission laser, les différents processus intervenant lors de cette diffusion ont été analysés: insertion du chrome dans la matrice par substitution, homogénéisation du dopage et mécanisme de recristallisation. Nous avons ainsi déterminé les paramètres gouvernant le mécanisme de diffusion du chrome dans le anse et réalisé des matériaux Cr2+ : ZnSe monocristallin et poly-cristallins à différents hauteurs de dopage en chrome (de 2. 10^18 à 5. 10^19 ions. Cm^(-3)). Par la suite, ces matériaux ont été caractérisés d'un point de vu spectroscopique. Il apparaît que la forme et la largeur des bandes d'absorption (1400-2200 nm), associées à la transitions 5T-2 → 5E de l'ion Cr2+ inséré dans le ZnSe sont peu différentes pour les matrices poly ou mono-cristallines. De même, le spectre de photo-luminescence (2000-3000 nm) mesuré à 300K, ne révèle aucune différence notable sur la forme du spectre à l'émission selon le type de matériau considéré. Par ailleurs, une caractérisation dynamique de ces matériaux indique des valeurs de temps de vie de l'état excité de l'ordre de 4 à 5 ms à 300K pour des dopages de l'ordre de 5. 10^18 ions. Cm^(-3). Enfin, l'efficacité à l'émission laser de ces matériaux a été étudiée. Dans une configuration de cavité laser identique, les efficacités laser optique-optique obtenue à partir de deux types de matériaux, mono (33%) et poly (28%) cristaux de Cr2+ : ZnSe, se sont avérés être comparables. Ce résultat est lié à la qualité optique du matériau polycristallin obtenue (grains de grande dimension) selon la procédure d'élaboration employée: Diffusion thermique. Une accordabilité en longueur d'onde entre 2. 2 et 2. 7 mM à partir de ces matériaux a également été obtenue à 300K. Nous avons ainsi démontré que les matériaux polycristallins Cr2+ : ZnSe présentent les propriétés optiques adaptées pour réaliser des sources laser opérant dans le MIR à température ambiante en compétition avec les matrices monocristallines
Development of efficient, compact, tunable solid state laser for the mid-infrared (MIR) at room temperature has initiated the study of transition metal ion TM doped II-VI compounds. Among those compounds, chromium ion incorporated into ZnSe host crystal represent a solid state laser material allowing radiative emission at room temperature in the spectral range of 2-3 mM. This work concern the study and realization of tunable, room temperature operating, solid state laser for MIR based on Cr2+ :ZnSe polycrystal. Advantages of polycrystals are mainly based on the elaboration cost and available dimension compared to the single crystals. We have elaborated Cr2+ :ZnSe laser materials by thermal diffusion doping method using both single and poly-crystals of ZnSe. Different process involved during the diffusion were analyzed like incorporation of chromium into substitutional site, homogenization of the doping and the recrystallization process. We have thus determined parameters governing the diffusion of chromium into the ZnSe and elaborated single and poly-crystals with different concentration on Cr (since 2. 10^18 to 5. 10^19 ions. Cm^(-3)). Then, we have proceed to spectroscopic characterization of those materials. We observed no difference in the shape and bandwidth of the absorption spectrum (1400-2200 nm) associated to the optical transition 5T-2 → 5E of Cr2+, inserted either in single or poly-crystal of ZnSe. The same observation was done concerning the shape of the room temperature photo-luminescence spectra (2000-3000 nm) obtained with either single or poly-crystal of Cr2+ :ZnSe. Furthermore, a dynamical characterization of such materials indicated an excited state lifetime at 300K in the order of 4 to 5 ms for Cr concentration of 5. 10^18 ions. Cm^(-3). Finally, laser efficiency of those materials were also studied. A comparable optical-optical laser efficiency were obtained, in a same laser cavity, with both Cr2+ :ZnSe materials : single-crystal (33%) and poly-crystal (28%). This result is deeply associated to the high optical quality of the poly-crystal (large grain size) laser material obtained using our elaboration method : Thermal diffusion doping. We have also obtained with such materials a tunability between 2. 2 to 2. 7 mM at room temperature. We have thus demonstrated that Cr2+ :ZnSe poly-crystals are highly efficiency, tunable, room temperature operating, laser materials for the MIR and are in competition with Cr2+ :ZnSe single-crystals

A method was developed which allowed for more consistent liposome quality, reducing the standard error of initial rates for Zn2+ diffusion by 30%. Introducing low concentration of platelet-activating-factor (PAF), 1-palmitoyl-L-lyso-3-phosphocholine (Lyso-PC), or 1-oleoyl-2-acetyl-sn-glycero-3-phosphocholine (Acyl-PAF) to 1palmitoyl.-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes did not have any noticeable impact on zinc diffusion. Since diffusion is dependent on membrane composition and properties, it can be concluded that PAF, Lyso-PC, and Acyl-PAF did not alter POPC liposome properties significantly. Zn2+ and Cd2+ kinetic experiments showed binding to the liposome surface prior to diffusion and a mutual diffusing species, the monohydroxo complex. Although Mn 2+ did not diffuse to any measurable extent, binding to the liposome surface was also observed. Cue+ and Pb 2+ on the other hand follow a more complex diffusion mechanism, which requires further investigation.
Department of Chemistry

L'influence des ions Pb2+ sur le dépôt de zinc a été étudiée dans l'électrolyte acide de sulfate de zinc avec et sans Mn2+. La polarisation galvanostatique, la polarisation potentiodynamique, la voltammétrie cyclique (VC), les mesures de bruit électrochimique (MBE) et la spectroscopie d'impédance électrochimique (SIE) en conjonction avec la microscopie électronique à balayage (MEB) et la diffraction des rayons-X (XRD) ont été considérés. L'effet de différents paramètres de fonctionnement tels que la concentration de Zn2+, la concentration d’acide sulfurique, la densité de courant, l'agitation de l’électrolyte et la température a été étudié en présence de Mn2+ et Pb2+. Les résultats galvanostatiques utilisant un électrolyte standard de zinc contenant 12 g/L de Mn2+ (ES) ont montré que les ions de plomb ajoutés à l’ES conduisaient à une augmentation du potentiel cathodique et de l'efficacité de courant (EC) du dépôt de zinc. L'augmentation de la concentration de Mn2+ dans l'électrolyte a entraîné une diminution du potentiel cathodique et d’EC du dépôt de zinc à cause de l'effet de dépolarisation du MnO4- formé. En outre, l'augmentation de la densité de courant de 45 à 60 mA/cm2 et de l'agitation de 60 à 412 tr/min ont donné lieu à une augmentation du potentiel et à une diminution d’EC. L'augmentation de la température de 35 à 45°C a conduit à une diminution du potentiel cathodique. Pour l'électrolyse de longue durée (72 h), la teneur de Pb dans le dépôt de zinc en utilisant l'anode Pb-0,7%Ag était de 1,90-1,98 ppm, presque équivalente à celle employant l'anode de Pt avec l’addition de 0,15-0,2 mg/L de Pb2 +. L'électrolyse à 40°C et 52,5 mA/cm2 en présence de plomb jusqu'à 0,1-0,2 mg/L dans un électrolyte contenant 12 g/L Mn2+ pourrait être considérée comme des meilleurs paramètres opérationnels pour le procédé d'extraction électrolytique. Les études SIE ont montré que le dépôt de zinc sur le zinc est plus facile que celui du zinc sur l'aluminium. L’analyse des MBE a révélé que l'augmentation des concentrations de Pb2+ (0,05-0,8 mg/L) dans l'électrolyte de zinc sans Mn2+ s'accompagne d'une diminution de l'inclinaison et d'une augmentation des valeurs du kurtosis qui puissent être corrélées à la morphologie du dépôt de zinc.
The influence of Pb2+ ions on zinc deposition was investigated in acidic zinc sulfate electrolyte with and without Mn2+ ions. Galvanostatic polarization, potentiodynamic polarization, cyclic voltammetry (CV), electrochemical noise measurements (ENM) and electrochemical impedance spectroscopy (EIS) in conjunction with scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been considered. Effects of different operating parameters such as Zn2+ ions concentration, sulfuric acid concentration, current density, electrolyte agitation and temperature were investigated in presence of Mn2+ and Pb2+ ions. The galvanostatic results using standard zinc electrolyte containing 12 g/L Mn2+ (SE) showed that lead ions added to the SE led to an increase in the cathodic potential and current efficiency (CE) of zinc deposit. Increasing Mn2+ concentration in the electrolyte resulted in decrease of cathodic potential and CE of zinc deposit due to the depolarization effect of formed MnO4-. In addition, increases of current density from 45 to 60 mA/cm2 and agitation from 60 to 412 rpm resulted in an increase of overpotential and decrease of CE. Increase of temperature from 35 to 45°C led to a decrease of cathodic potential. For long time electrolysis (72 h), the Pb content in zinc deposit using Pb-0.7%Ag anode was 1.90-1.98 ppm, almost equivalent to that employing Pt anode with addition of 0.15-0.2 mg/L of Pb2+. Electrolysis at 40°C and 52.5 mA/cm2 in presence of lead up to 0.1-0.2 mg/L in an electrolyte containing 12 g/L of Mn2+ could be considered as best conducted operating parameters for electrowinning process. EIS studies showed that zinc deposition on zinc is easier than that of zinc on aluminum. ENM revealed that increase of Pb2+ concentration (0.05-0.8 mg/L) in zinc electrolyte without Mn2+ is accompanied with a decrease of skew and increase of kurtosis values that could be correlated to the morphology of zinc deposit.

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química
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O presente trabalho propôs avaliar o potencial do ligante N,N',N,N'-bis[(2-hidroxi-3,5-di-terc-butilbenzil)(2-piridilmetil)]-etilenodiamina na extração líquido-líquido dos íons Cd2+, Cu2+, Mn2+, Ni2+ e Zn2+. O ligante foi sintetizado e caracterizado por análise elementar de C e N, espectroscopia no infravermelho e ressonância magnética nuclear. Realizou-se estudos de determinação do pH ótimo de extração, determinou-se a capacidade máxima de extração, além da cinética de extração e suas constantes de velocidade. Verificou-se a seletividade de extração, bem como, realizou-se estudos de pré-concentração de íons Cu2+ e de interferência de outros íons. Os resultados obtidos permitem demonstrar que a extração dos íons metálicos é dependente do pH. Na determinação da capacidade máxima de extração, observou-se que o ligante foi mais efetivo na extração dos íons Cd2+, Cu2+ e Zn2+ do que os íons Mn2+ e Ni2+. Os estudos cinéticos revelaram que o tempo para atingir o equilíbrio de extração dos íons Cd2+, Cu2+ e Zn2+ foi menor quando comparado ao dos íons Mn2+ e Ni2+. A partir das constantes de velocidade, obteve-se a ordem de extração como sendo Cu >> Cd ³ Zn >> Mn >> Ni. O ligante apresentou alta seletividade na extração dos íons Cu2+ em pH 4,0. Por fim, nos estudos de pré-concentração, observou-se que o ligante foi capaz de extrair 100 % dos íons Cu2+ em solução tampão e em água mineral, mesmo em presença dos demais íons.

L’intérêt de la nanofiltration est grandissant dans la dépollution des effluents industriels et le recyclage des eaux. Une méconnaissance du comportement du matériau membranaire et des phénomènes de transfert limitent son application. Il apparaît donc qu’une meilleure compréhension des mécanismes de transport favoriserait considérablement son essor au sein d’un procédé industriel en particulier la galvanoplastie. C’est dans cet optique que nous avons mené notre travail de thèse pour contribuer à l’étude de l’élimination des ions zinciques par NF. La première partie de ce rapport traite les problématiques des rejets industriels métalliques en général et zinciques en particulier dans le milieu naturel. La deuxième partie présente le dispositif expérimental et les résultats obtenus ressortant ainsi les propriétés sélectives de la membrane Nanomax 50 utilisée. La troisième partie applique et confronte les modèles de transfert dérivés de l’équation de Nernst-Planck étendue associée d’une part à la théorie du film et d’autre part à la théorie du pore.

Ein fundiertes Verständnis der Mechanismen der Gummi-Vulkanisation von Dien-Kautschuken ist noch immer eine der größten Herausforderungen in der Chemie und Technologie der Elastomere. Die Schwefelvulkanisation von Elastomerwerkstoffen ist ein seit langem verwendeter, aber dennoch sehr anspruchsvoller Prozess, mit dessen Hilfe moderne Reifen hergestellt werden. Bei dieser chemischen Reaktion spielt Zinkoxid, zusammen mit den anderen Hilfsstoffen der Schwefelvulkanisation eine entscheidende Rolle. Um die Produkteigenschaften von mit Schwefel vulkanisierten Elastomermaterialien zu verbessern, sollten die Mechanismen der chemischen Vernetzung - und insbesondere auch die Rolle von Zink enthaltenden Verbindungen bei der Vulkanisationsreaktion besser verstanden werden. Zum Beispiel könnte das Eigenschaftsprofil von Reifen durch die Ausbildung von geeigneten Netzwerken aus Schwefel oder anderen Netzknoten optimiert werden. Nitrilkautschke aus der Klasse der Spezialelastomere und die meisten nicht-Tire- Kautschuk in der ganzen Welt eingesetzt, wecken ein großes Interesse der Forschung wegen ihrer einzigartigen Vulkanisationschemie bei der Vernetzung mittels Zinkverbindungen und wegen der besonderen Eigenschaften der dadurch erzeugten Elastomerwerkstoffe. In dieser Arbeit wurde besonderes Augenmerk darauf gelegt, die Rolle von verschiedenen Zinkverbindungen in der Schwefelvulkanisation von carboxylierten Nitrilkautschuken zu verstehen. In der vorliegenden umfangreichen und eingehenden Untersuchung konnte die Ausbildung einer weiteren Polymerphase im Elastomer nachgewiesen werden. Durch dieses Ergebnis kann nun das dynamische mechanische Verhalten von solchen Polymerwerkstoffen besser verstanden werden. Teile dieser Arbeit beschäftigen sich mit der Erforschung der Rolle von Zinkchlorid bei der Vernetzung von Nitrilkautschuken. Hierzu wurde festgestellt, dass Zinkchlorid einen besonderen Einfluss auf die chemische Vernetzung des NBR aufweist, auch in Abwesenheit anderer Vernetzungs- oder Vulkanisationsadditive. Die so vernetzten Elastomere weisen ein stark hydrophiles Verhalten auf, im Gegensatz zu den allgemeinen Eigenschaften solcher Elastomerwerkstoffe. Eine detaillierte Analyse dieser neuartigen Netzwerkstruktur, gebildet durch eine Koordinationsbindung zwischen dem Zinkatom des Zinkchlorids und dem Nitrilkautschuk, wurde durchgeführt. Carboxylierter Nitrilkautschuk (XNBR) wurde ebenfalls eingesetzt, um funktionale Kautschukmischungen mit neuartigen flammhemmenden Eigenschaften zu entwickeln. Zu dieser Thematik wurden Zink enthaltende Doppelhydroxide (Layered Doube Hydroxides, LDH) als multifunktionale Füllstoffe in XNBR-Kautschuk eingesetzt. Neben dem Flammschutzverhalten zeigt LDH einzigartige Eigenschaften als verstärkenden Füllstoff und gleichzeitig als aktivierendes Additiv für die Schwefelvulkanisation. Eine weitere Zink enthaltenden Verbindung, Zinkstearat, wurde eingesetzt um mechanoadaptive elastomere Materialien durch gezieltes Einstellen des kristallinen bzw. amorphen Charakters dieser Verbindung zu entwickeln. Dies könnte einen wichtigen Beitrag zur Entwicklung zukünftiger Reifenmaterialien mit intrinsisch adaptiven Eigenschaften liefern.

Ion exchange of heavy metals with zeolites is important in terms of different application areas. Industrial wastewater treatment and antibacterial applications are two essential areas that have taken great attention. While silver, zinc and copper are well known for their toxicity, they are also used as antibacterial agents in zeolites. The objective of this study is to investigate the single and multicomponent ion exchange behavior of zeolite 4A for silver, zinc, copper and sodium ions. For this purpose Ag+-Na+, Zn2+-Na+, Cu2+-Na+ binary systems and Ag+-Zn2+-Na+, Ag+-Cu2+-Na+, Cu2+-Zn2+-Na+ ternary systems were investigated in batch systems at 25°
C and 0.1 N. Binary ion exchange isotherms indicate that zeolite 4A has high selectivity for silver, zinc and copper with respect to sodium. All exchange isotherms lie above the diagonal over the whole range. Using the equilibrium data, the thermodynamic analysis of the binary systems were carried out. The thermodynamic equilibrium constants and the standard free energies of exchange were calculated as 340.9 and -14.5 kJ/mol for silver-sodium system, 40.5 and -4.6 kJ/mol for zinc-sodium system, and 161.2 and -6.3 kJ/mol for copper-sodium system, respectively. From these values, selectivity sequence of zeolite 4A was determined as Ag+ >
Cu2+ >
Zn2+. This selectivity sequence was also verified by the results of ternary ion exchange experiments. The experimental data were compared with the Langmuir and Freundlich isotherms. While Freundlich model gives a better correlation for Ag+-Na+ and Zn2+-Na+ exchange, Langmuir model represents a better fit to the experimental data of Cu2+-Na+ exchange.

Ces travaux de thèse se sont focalisés sur la miniaturisation d'une batterie zinc-air, dispositif qui présente l'avantage d'avoir une densité d'énergie massique et volumique théorique supérieure à celle de la technologie lithium-ion, majoritairement étudiée dans la littérature. Le micro-usinage d'un substrat de silicium permet de définir le squelette d'électrodes à forte surface spécifique : le gain géométrique des structures 3D se répercute alors sur les performances de stockage des charges des électrodes de la microbatterie. Différentes géométries de microstructures 3D ont été étudiées : à titre d'exemple, des tubes de taille micrométrique (4,2μm de diamètre), profonds de 109μm (rapport d'aspect de 60: 1) permettent d'obtenir un rapport entre la surface spécifique et l'empreinte surfacique de 70. Ce squelette est ensuite recouvert de matériaux actifs à l'aide de procédés de dépôts conformes. Cette démarche a permis la mise au point d'une électrode métallique 3D en zinc (couche mince de 300nm) présentant une capacité spécifique de 1mAh.cm-2 en milieu aqueux (hydroxyde de potassium 0,7M). La tension de la cellule est de 1,2V. Pour la première fois, une électrode à air miniaturisée a été fabriquée, basée sur la création d'un réseau de micro-canaux poreux sur la face avant du substrat silicium, et la gravure d'une cavité sur la face arrière. Dès lors que le silicium est usiné, un dépôt de platine permet d'assurer le caractère conducteur de l'électrode tandis qu'un dépôt de dioxyde de manganèse lui apporte des propriétés catalytiques. Ce concept original d'électrode à air 30 présente un fonctionnement similaire à une électrode commerciale, malgré une taille bien plus réduite
The studies presented in the frame of this thesis are focused on zinc-air battery miniaturization, an electrochemical energy storage system that shows a higher volumetric and gravimetric energy density than the lithium-ion technology, mostly investigated in literature. The micromachining of a silicon substrate allows designing a high specific surface scaffold: 3D geometrical gain enhances the properties of charge storage for the electrodes of the microbattery. 3D microstructures exhibiting various geometrical designs have been studied: for instance, silicon micro-tubes (4,2μm outer diameter) 109 μm-depth (60:1 aspect ratio) provide a specific surface to the footprint ratio close to 70. Then, this scaffold is coated by the active materials using conformal depositions methods. This process leads to a 3D zinc metallic anode (300nm-thick) exhibiting a surface capacity of 1mAh.cm-2 in aqueous electrolyte (potassium hydroxide 0,7M). Cell voltage is 1,2V. For the first time in literature, a miniaturized air electrode has been manufactured, based on a porous microchannel network on the front side of silicon substrate, and the etching of a cavity on the back side. Once silicon wafer is micromachined, a platinum conformal thin film provides the conductive properties to the electrode while a manganese dioxide layer enhances the catalytic activity. This original concept of 3D air electrode presents a behavior similarly to a commercial one, but with a significant reduced size

La maladie d'Alzheimer (MA) est une maladie neurodégénérative. Elle représente entre 60-80 % des cas de démence et touche autour de 47 millions de personnes à travers le monde. Deux types de lésions morphologiques de la MA ont été identifiés post mortem : les enchevêtrements neurofibrillaires intra-neuronaux de protéine Tau hyperphosphorylée et les plaques séniles. Les plaques séniles, ou plaques amyloïdes, se forment dans l'espace extracellulaire entre les fentes synaptiques et empêchent les connexions neuronales. Le composant principal de ces plaques est le peptide Amyloïde-ß (Aß) agrégé. Une hypothèse concernant cette maladie propose une mauvaise régulation des ions métalliques, telles que Zn et Cu, et une accumulation de Aß. Cette hypothèse est appelée hypothèse de la cascade amyloïde. Dans cette hypothèse le peptide Aß monomérique, présent aussi dans les cerveaux sains, agrège d'abord en formes oligomériques, puis en fibres, qui vont ensuite constituer les plaques amyloïdes. Il est proposé que le zinc stabilise davantage les fibres et le cuivre les formes oligomériques. Ces formes présentent une grande toxicité liée à la production d'Espèces Réactives de l'Oxygène (ERO), en présence d'un réducteur tel que l'ascorbate. Ces espèces oxydantes sont délétères pour les molécules environnantes. Pour mieux comprendre comment les ions Zn(II) et Cu(II) vont moduler ou induire l'agrégation, leur impact est étudié en comparaison avec le peptide Amyloïde-ß murin (mAß). En effet, les rats et les souris partagent ce peptide et ne développent pas la MA. Le mAß diffère du Aß humain (hAß) par seulement 3 acides aminés sur les 40-42 acides aminés qui constituent la séquence hAß. Pour cette raison, une étude de l'impact de la différence de coordination des ions Zn(II) et Cu(II) au sein des deux peptides sur l'agrégation et la morphologie des agrégats est ici menée. Ceci a pour objectif d'aider une meilleure compréhension de la cascade amyloïde. La deuxième partie de cette thèse se focalise sur la production d'ERO. Jusqu'à récemment, les études étaient focalisées sur les peptides Aß1-n (n=16/28/40/42). Celui ici, en présence des ions cuivre, de dioxygène et d'ascorbate va produire des ERO. Cependant, il est démontré qu'une forte quantité de formes tronquées en position N-terminale du Aß (en particulier Aß4-n et Aß11-n) se trouvent dans les cerveaux post mortem des malades d'Alzheimer. Ces deux peptides présentent un site de coordination pour le Cu(II) de type ATCUN, qui peut donc coordonner fortement les ions Cu(II). Il est donc intéressant d'étudier leur capacité à produire des ERO et/ou capacité à en arrêter la production. Enfin, l'impact du Zn(II) sur la production d'ERO par les complexes AßCu a été évalué, car la concentration en Zn dans les fentes synaptiques est environ 100 fois plus grande que celle en Cu
Alzheimer's disease (AD) is a neurodegenerative disease and it represents the 60-80 % of the dementia cases. It touched around 47 million people worldwide. Two hallmarks of AD were identified in post mortem brain: the intracellular neurofibrillary tangles of hyperphosphorylated Tau protein and the amyloid (or senile) plaques. The amyloid plaques are formed in the extracellular space in the synaptic cleft. These aggregates would prevent the neuronal connections. The major component of the senile plaques is the aggregated Amyloid-ß (Aß) peptide. An hypothesis concerning this disease proposed a metal ions dyshomeostasis and an accumulation of Aß. This hypothesis is called amyloid cascade hypothesis. According to this hypothesis, the monomeric Aß peptide, present also in the healthy brains, aggregates into dimer, trimer... and more generally into oligomers; and then into fibers, which constitute the amyloid plaques. It is considered that zinc ions stabilize the fibers and copper ions the oligomeric forms. These forms present a high toxicity linked to the production of Reactive Oxygen Species (ROS), in the presence of dioxygen and a reducing agent such as ascorbate. These oxidants species are toxic for the surrounding molecules. To better understand how Zn(II) and Cu(II), modulate and/or induce the aggregation of the Aß peptide, their impact was studied and compared to the murine amyloid-ß (mAß) peptide. Indeed, rats and mice share this peptide and do not develop AD. mAß peptide differs from the human (hAß) peptide at 3 only positions on the 40-42 amino acids which constitute the hAß sequence. For this reason, a study of the impact of the different Zn(II) and Cu(II) coordination on the aggregation and on the morphology of aggregates of both peptides was performed. This aims at helping to better describe amyloid cascade hypothesis. The second part of this thesis focuses on ROS production. Until recently, the studies were focused on the peptides Aß1-n (n=16 / 28 / 40 / 42). These peptides in presence of copper ions, O2 and ascorbate produce ROS. However, a high amount of N-truncated Aß peptides, in particular Aß4-n and Aß11-n, was found post mortem in AD brains. These two peptides have an ATCUN coordination site, which strongly coordinates the Cu(II). It is interesting to study their ability to produce or stop ROS production. Finally, the impact of the Zn(II) in the ROS production of AßCu complexes is evaluated. Indeed, the concentration of Zn in the synaptic cleft is around 100 times more than Cu

Action de divers organometalliques sur des ions carboxonium et carbonium: 1) les organoaluminiques allyliques reagissent avec le tetrafluoroborate de dithienium pour donner des 2-alkyl-1,3-dithianes; 2) les organoaluminiques prepares a partir de bromures alpha-ethyleniques et alpha-acetyleniques reagissent avec un sel de diethoxy-carbonium pour donner des acetals beta-insatures; 3) les organolithiens prepares a partir d'halogenures vinyliques ou d'alc-1-ynes reagissent avec le tetrafluoroborate de triethoxycarbonium pour donner des ortho-esters alpha-insatures; 4) les organolithiens, les organoaluminiques et organozinciques prepares a partir de bromures alpha-insatures, les organosilanes allyliques reagissent avec le tetrafluoroborate de tropylium pour donner des 7-alkylcyclohepta-1,3,5-trienes. Nouvelle methode d'activation du zinc: l'addition d'une petite quantite de chlorotrimethylsilane a une suspension de zinc dans l'ether permet de preparer facilement des beta-hydroxyesters a partir de bromoethanoates d'alkyle et de composes carbonyles, et de preparer des alcools beta-ethyleniques a partir de bromures alpha-ethyleniques et de composes carbonyles

The sharply rising level of atmospheric carbon dioxide resulting from anthropogenic emissions is one of the greatest environmental concerns facing our civilization today. Metal-organic frameworks (MOFs) are a new class of materials that constructed by metal-containing nodes bonded to organic bridging ligands. MOFs could serve as an ideal platform for the development of next generation CO2 capture materials owing to their large capacity for the adsorption of gases and their structural and chemical tunability. The ability to rationally select the framework components is expected to allow the affinity of the internal pore surface toward CO2 to be precisely controlled, facilitating materials properties that are optimized for the specific type of CO2 capture to be performed (post-combustion capture, precombustion capture, or oxy-fuel combustion) and potentially even for the specific power plant in which the capture system is to be installed. For this reason, significant effort has been made in recent years in improving the gas separation performance of MOFs and some studies evaluating the prospects of deploying these materials in real-world CO2 capture systems have begun to emerge. We have developed six new MOFs, denoted as IFPs (IFP-5, -6, -7, -8, -9, -10, IFP = Imidazolate Framework Potsdam) and two hydrogen-bonded molecular building block (MBB, named as 1 and 2 for Zn and Co based, respectively) have been synthesized, characterized and applied for gas storage. The structure of IFP possesses 1D hexagonal channels. Metal centre and the substituent groups of C2 position of the linker protrude into the open channels and determine their accessible diameter. Interestingly, the channel diameters (range : 0.3 to 5.2 Å) for IFP structures are tuned by the metal centre (Zn, Co and Cd) and substituent of C2 position of the imidazolate linker. Moreover hydrogen bonded MBB of 1 and 2 is formed an in situ functionalization of a ligand under solvothermal condition. Two different types of channels are observed for 1 and 2. Materials contain solvent accessible void space. Solvent could be easily removed by under high vacuum. The porous framework has maintained the crystalline integrity even without solvent molecules. N2, H2, CO2 and CH4 gas sorption isotherms were performed. Gas uptake capacities are comparable with other frameworks. Gas uptake capacity is reduced when the channel diameter is narrow. For example, the channel diameter of IFP-5 (channel diameter: 3.8 Å) is slightly lower than that of IFP-1 (channel diameter: 4.2 Å); hence, the gas uptake capacity and Brunauer-Emmett-Teller (BET) surface area are slightly lower than IFP-1. The selectivity does not depend only on the size of the gas components (kinetic diameter: CO2 3.3 Å, N2 3.6 Å and CH4 3.8 ) but also on the polarizability of the surface and of the gas components. IFP-5 and-6 have the potential applications for the separation of CO2 and CH4 from N2-containing gas mixtures and CO2 and CH4 containing gas mixtures. Gas sorption isotherms of IFP-7, -8, -9, -10 exhibited hysteretic behavior due to flexible alkoxy (e.g., methoxy and ethoxy) substituents. Such phenomenon is a kind of gate effects which is rarely observed in microporous MOFs. IFP-7 (Zn-centred) has a flexible methoxy substituent. This is the first example where a flexible methoxy substituent shows the gate opening behavior in a MOF. Presence of methoxy functional group at the hexagonal channels, IFP-7 acted as molecular gate for N2 gas. Due to polar methoxy group and channel walls, wide hysteretic isotherm was observed during gas uptake. The N2 The estimated BET surface area for 1 is 471 m2 g-1 and the Langmuir surface area is 570 m2 g-1. However, such surface area is slightly higher than azolate-based hydrogen-bonded supramolecular assemblies and also comparable and higher than some hydrogen-bonded porous organic molecules.
Metallorganische Gerüstverbindungen (MOFs) sind eine neue Klasse von porösen Koordinationspolymeren, die aus Metall-Knoten und verbrückenden Liganden bestehen. MOFs können Gasgemische trennen und Gase speichern. Aufgrund ihres modularen Aufbaus können die MOF-Eigenschaften systematisch variiert werden. Ein wichtiges Ziel für das Design von MOFs ist die Synthese von Materialien, die eine hohe selektive Aufnahmefähigkeit und -kapazität für Kohlenstoffdioxid besitzen. Im Rahmen der Arbeit ist es gelungen sechs neue MOFs (IFP-5, -6, -7, -8, -9 und -10) zu synthetisieren. Diese MOFs tragen die Kurzbezeichnung IFP. IFP steht als Abkürzung für Imidazolat-Framework-Potsdam (Imidazolat-basierte Gerüstverbindung Potsdam). In diesen IFPs wurde der Metallknoten (Zink, Cobalt, Cadmium) und der Brückenligand, ein 2-substituiertes Imidazolat-amid-imidat, in der Position variiert, um gute und selektive Sorptionseigenschaften für Kohlenstoffdioxid zu erzielen. Von den synthetisierten Verbindungen hat das IFP-5 die besten Sorptionseigenschaften für Kohlenstoffdioxid. Es konnte weiter gezeigt werden, dass sich die IFP-Struktur bei der Wahl von geeigneten Substituenten 2, wie z.B. Methoxy und Ethoxy auch für das Design von gate-opening (Tür-öffnenden) Effekten eignet. Diese Effekte können wiederum genutzt werden, um selektiv Gasmischungen zu trennen. Wenn man das 4,5-Dicyano-2-methoxy-imidazol in Gegenwart von Zink- und Cobalt-Salzen unter solvothermalen Bedingungen zur Reaktion bringt, erhält man beispiellose supramolekulare Wasserstoffbrückenbindungen zu einem dreidimensionalen Netzwerk, die mit Kanälen verknüpft sind. Diese Kanäle können von Lösungsmittelmolekülen (Wasser und Dimethylformamid) befreit werden und Gase aufnehmen. Insgesamt besteht nun die neue MOF-Klasse der Imidazolat-basierten IFPs aus Vertretern. Das Potential der 2-substituierten 4,5-Dicyanoimidazole ist nicht nur auf die Bildung von porösen Koordinationspolymeren beschränkt, sondern kann auch für die Synthese von bisher unbekannten supramolekularen Strukturen genutzt werden.

[ES] Los procesos de comunicación celular permiten a las células desarrollar una acción coordinada durante la embriogénesis y asimilar de forma coherente las señales recibidas a través del entorno. Algunas de las moléculas señalizadoras más usadas en la clínica y la investigación son las citoquinas. Sin embargo, existe una tendencia creciente en el uso de otro tipo de moléculas, como los iones metálicos. Algunos iones como el calcio y el zinc actúan como segundos mensajeros intracelulares. Otros como el litio son capaces de inactivar proteínas quinasa alterando rutas de señalización. En el desarrollo de esta tesis doctoral, se ha estudiado el efecto del zinc en células musculares de ratón, el papel del zinc en la auto-renovación de células madre embrionarias (CMEs), y el papel del litio en la diferenciación de CMEs. El estudio del efecto del zinc sobre los mioblastos demostró que el zinc es capaz de estimular la diferenciación de los mioblastos. El análisis del zinc intracelular, en los diferentes estadios de diferenciación de las células musculares, demostró que los miotubos eran capaces de albergar mayor cantidad de zinc en su interior. Los resultados mostraron que la adición de zinc extracelular estimula la fosforilación y activación de la proteína quinasa Akt. También se ha visto que el transportador de zinc, Zip7, es crítico en el proceso de diferenciación celular mediado por el zinc, además, su activación incrementa la fosforilación de Akt. La inhibición de Zip7 mediante ARN interferente redujo la fosforilación de Akt y consecuentemente origino unos niveles menores de diferenciación de los mioblastos expuestos a zinc extracelular. Nuestros resultados demuestran que altas concentraciones de zinc extracelular producen un incremento en la diferenciación de los mioblastos debido a la activación de Akt mediada por Zip7. Para el segundo estudio, se analizó el efecto del zinc sobre las CMEs. Como control de mantenimiento de la pluripotencia se usó medio suplementado con factor inhibidor de leucemia (LIF). Se ha observado que la adición externa de concentraciones de zinc superiores a 100 µM produce un incremento inmediato de la concentración de zinc intracelular activando Akt. Los resultados demuestran que las células tratadas con altas concentraciones de zinc mantienen su capacidad de auto-renovación. Para demostrar que el efecto del zinc en CMEs está asociado a la activación de Akt mediada por Zip7, se inhibió la fosforilación de Akt y se silenció Zip7. Ambos abordajes dieron como resultado un incremento en la diferenciación de las células tratadas con zinc. Por otro lado, CMEs cultivadas durante 30 días en presencia de zinc fueron capaces de retener su pluripotencia, mientras que el control sin zinc presentaba rasgos claros de diferenciación celular. Por último, la combinación de LIF con zinc produjo un incremento importante del efecto del LIF en cuanto al mantenimiento de la capacidad de auto-renovación celular. Por último, se ha estudiado el efecto del litio en la diferenciación de las CMEs. El litio es un inhibidor de la glucógeno sintasa quinasa 3ß (GSK3ß). En términos de CMEs, GSK3ß activa los mecanismos de diferenciación. Los resultados obtenidos indican que altas concentraciones de litio (10 mM) son capaces de fosforilar e inhibir la proteína GSK3ß. Sin embargo, en lugar de mantener la pluripotencia, las células madre se diferenciaron hacia el linaje del mesodermo tras 3 días de cultivo. Después de un total de 6 días, las células tratadas con 10 mM de litio presentaron características de endotelio hemogénico. La inhibición de GSK3ß dio como resultado la activación de la proteína ß-catenina, cuya actividad transcripcional es necesaria para la hematogénesis embrionaria. La capacidad de las células endoteliales con potencial hemogénico obtenidas de derivar en células madre hematopoyéticas fue confirmada tras su maduración durante 11 día
[CAT] Els processos de comunicació cel·lular permeten a les cèl·lules desenvolupar una acció coordinada durant la embriogènesis y assimilar de forma coherent als senyals rebudes a través de l'entorn. Algunes de les molècules senyalitzadores més usades en la clínica i la investigació són les citocines. No obstant, hi ha una tendència creixent en l'ús d'un altre tipus de molècules, com els ions metàl·lics. Alguns ions com el calci i el zinc són capaços de dur a terme funcions de missatger secundari. Altres com el liti són capaços d'inactivar proteïnes quinasa alterant rutes de senyalització. Durant el desenvolupament d'aquest treball de tesi doctoral, s'ha estudiat l'efecte del zinc sobre mioblasts de ratolí, el paper del zinc en l'auto-renovació de les cèl·lules mare embrionàries (CMEs), i el paper del liti sobre la diferenciació de les CMEs. L'estudi de l'efecte del zinc sobre els mioblasts ha demostrat que el zinc és capaç d'incrementar la diferenciació dels mioblasts. L'anàlisi del zinc intracel·lular ha demostrat que els mioblasts diferenciats eren capaços d'albergar major quantitat de zinc intracel·lular. Els resultats han mostrat que suplementar les cèl·lules amb zinc extracel·lular produïx una major fosforilació i activació de la proteïna quinasa Akt. D'altra banda, s'ha observat que el transportador de zinc Zip7 es crític per a la diferenciació cel·lular mediada pel zinc. S'ha demostrat que l'activació d'aquest transportador mitjançant zinc extracel·lular és capaç d'incrementar la fosforilació d'Akt. La inhibició d'aquest transportador mitjançant ARN interferent ha donat com a resultat una menor fosforilació d'Akt i una menor diferenciació dels mioblasts exposats a zinc. Aquests resultats demostren que altes concentracions de zinc extracel·lular produeixen un incrementar la diferenciació dels mioblasts a causa de l'activació d'Akt per mitja de Zip7. Per al segon estudi, s'ha analitzat l'efecte del zinc sobre les CMEs. Com a control de manteniment de la pluripotència es va usar medi suplementat amb factor inhibidor de leucèmia (LIF). S'ha observat que les concentracions extracel·lulars de zinc a partir de 100 µM produïxen un increment immediat de la concentració intracel·lular, produint l'activació d'Akt per mitja de Zip7. Les CMEs tractades amb altes concentracions de zinc mantenen l'auto-renovació. Per demostrar que aquest efecte està associat a l'activació d'Akt mediada per Zip7, es va inhibir la fosforilació d'Akt i es va silenciar el transportador Zip7. Tots dos abordatges han donat com a resultat un increment en la diferenciació de les CMEs tractades amb zinc. D'altra banda, les CMEs van ser capaços de retenir la seva pluripotència després de ser cultivades durant 30 dies en presència de zinc, mentre que el control sense zinc presentava trets clars de diferenciació cel·lular. Finalment, la combinació de LIF amb zinc ha produit un increment sinèrgic de l'efecte del LIF. Finalment, també s'ha estudiat l'efecte del liti en la diferenciació de les CMEs. El liti és un inhibidor de la glicogen sintasa quinasa 3 beta (GSK3ß). En termes de CMEs, aquesta proteïna activa els mecanismes de diferenciació. Els resultats obtinguts indiquen que altes concentracions de liti (10 mM) tenen la capacitat de fosforilar i inhibir la proteïna GSK3ß. No obstant això, en lloc de mantenir la pluripotència, les CMEs es van diferenciar cap al llinatge del mesoderma després de 3 dies. Després d'un total de 6 dies, les cèl·lules tractades amb 10 mM de liti presentaven característiques d'endoteli hemogénic. La fosforilació de GSK3ß va donar com a resultat l'activació de la proteïna ß-catenina, l'activitat trasncripcional d'aquesta proteïna és necessària per a la hematogénesis embrionària. La capacitat de les cèl·lules endotelials amb potencial hemogénic obtingudes de derivar en cèl·lules mare hematopoètiques va ser confirmada després de la
[EN] The cell signalling process allows cells to develop a coordinated action during embryogenesis and assimilate coherently the signals received through the environment. Some of the most currently used signalling molecules in clinics and research are growth factors and cytokines. However, there is a growing trend in the use of other types of molecules, such as metal ions. Some ions such as calcium and zinc are able to carry out secondary messenger functions, transmitting signals in cascade. Others ions, such as lithium, are capable to inactivate protein kinases altering signalling pathways. During the development of this doctoral thesis, we investigated the effect of zinc on mouse muscle cells (myoblasts), the role of zinc in embryonic stem cells (ESCs) self-renewal, and the role of lithium in the differentiation of ESCs. In the first chapter, we showed that zinc is able to increase the differentiation of myoblasts. The analysis of intracellular zinc indicated that the differentiated myoblasts were capable to harbour higher concentration of intracellular zinc than undifferentiated ones. Addition of high concentration of extracellular zinc increased protein kinase Akt phosphorylation and activation. Akt activity is critical for myoblasts differentiation and has been well studied by other authors. Our results indicated that zinc transporter Zip7 was critical for zinc-mediated cell differentiation. It was prior demonstrated that the activation of this transporter by extracellular zinc increased the phosphorylation of Akt. The inhibition of Zip7 by interfering RNA resulted in a lower phosphorylation of Akt and reduced differentiation of the myoblasts exposed to extracellular zinc. These results demonstrated that high concentration of extracellular zinc enhances the differentiation of myoblasts through activation of Akt mediated by Zip7. In the second chapter, we have analysed the effect of zinc on ESCs. Leukaemia inhibitory factor (LIF) was used as pluripotency sustaining factor. We observed that extracellular supplementation of 100 ¿M zinc produced an immediate increase of the intracellular concentration, which resulted in the activation of Akt mediated by Zip7 transporter. ESCs treated with high concentrations of zinc maintained self-renewal. The role of Akt on ESCs self-renewal has been well established in the literature. To demonstrate that this effect is associated with the activation of Akt mediated by Zip7, we inhibited Akt phosphorylation and silenced the expression of Zip7. Both approaches resulted in an increase in the differentiation levels of the ESCs treated with zinc. We further demonstrated that ESCs treated with zinc during 30 days were able to retain their pluripotency, while the control condition cultured 30 days without zinc presented evident traits of spontaneous cellular differentiation. Finally, the combination of LIF with zinc produced a synergistic-like increase in the effect of LIF on ESCs self-renewal. Finally, we addressed the effect of lithium on the differentiation of ESCs. Lithium is an inhibitor of glycogen synthase kinase 3 beta (GSK3ß). In terms of ESCs, GSK3ß activates differentiation mechanisms. Our results indicated that high concentration of lithium (10 mM) was able to phosphorylate and strongly inhibit the activity of GSK3ß. However, instead of maintaining pluripotency, ESCs differentiated into the mesoderm lineage after 3 days of culture. After a total of 6 days, ESCs treated with 10 mM lithium showed haemogenic endothelium characteristics, expressing CD31, Sca-1 and CD31/Sca-1 positive cells. The phosphorylation of GSK3ß resulted in the activation of the ß-catenin protein, whose transcriptional activity is necessary for embryonic hematogenesis. The ability of endothelial cells with hemogenic potential obtained from lithium-treated ESCs to derive into hematopoietic stem cells was confirmed after maturation of these cells, resulting in rounded cell aggregates positive for Sox17.
Ministerio de Ciencia, Innovación y Universidades a través de la beca BES-2013-064052 y los proyectos MAT2012-38359-C03-01 y MAT2015-69315-C3-1-R.
Mnatsakanyan Movsesyan, H. (2019). ROLE OF IONS IN STEM CELLS SIGNALLING [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/123063
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