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1
Watson, Jeanette Esther, and mikewood@deakin edu au. "Studies on Australian hydroids the genus eudendrium and the fauna of the seagrass amphibolis." Deakin University. School of Science, 1990. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20050825.121035.
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An important Athecate genus, Eudendrium, and a group of species of the Thecata, the latter ecologically related by life on a common substrate, are reviewed.
Eudendrium, hitherto poorly known in Australia, comprises 17 species, including 10 undescribed species with 71% Australian, and high provincial endemicity. Eudendrium may be a shelf genus avoiding turbulent oceanic waters. Species of Eudendrium are predominantly epizoic and some gregariously settling colonies may live for five years. Identification of sterile material is refined by using the cnidome in a key to classification.
The species and population dynamics of hydroid epiphytes of the endemic southern Australian marine angiosperm Amphibolis were investigated with revision of historically vexatious taxa. In contrast with the northern hemisphere, no Athecata are associated with southern Australian seagrasses. Seventeen species from eight thecate families are associated with the two species of Amphibolis, including one undescribed species, H&lecium amphibolum, and one new record for Australia, Aglaophenia postdentata. The Lineolariidae is revised and a new genus, Millardaria, erected for a species from seagrass in Madagascar. The high endemicity (58%) and host-specificity of hydroids to Amphibolis is an evolutionary consequence of isolation of the seagrass dating from break-up of the Tethyan Sea.
Hydroids occur throughout the year in the Amphibolis leaf canopy with a mean annual epiphytism of 44% on A. antarctica in the eastern continent and 86% in the western continent; epiphytism is 52% on A. griffithii in the western continent. Half of the eight important species are dominant epiphytes across the southern continent but the species and order of abundance varies regionally. Most are pioneer colonists with short, repetetive life-cycles lasting from weeks to a few months.
Three species epiphytise the seagrass stems but only one is a leaf-canopy dominant. The canopy community comprises small, fast-growing species or dwarfed variants of species larger in other habitats: these ecomorphically constant forms are associated only with seagrass. Strategies for survival in the harsh Amphibolis environment include adnate colonies and gonothecae adnate or recumbent to the substrate, marked strengthening of the hydrorhiza, various hydrodynamic adaptations of the hydrotheca, early maturation and production of numerous small ova.
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Kunovjánek, Miroslav. "Studium vodivosti PVA membrán, obsahujících alkalické hydroxidy." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-234580.
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Thesis deals with study of separators and membranes, suitable for using in alkali electrochemical applications like fuel cells or electrolysis. As basic material for membranes production is used polyvinylalkohol (PVA). Various methods of PVA cross linking are introduced in the thesis. PVA membranes are also doped by various types of additives to improve the attributes of the membranes like mechanical stability and or conductivity. The aim of the work is verification of parameters of membranes, doped by alkali hydroxides KOH, NaOH and LiOH at various temperatures. These hydroxides are added to the membrane especially for increasing of membrane conductivity.
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Čech, Ondřej. "Vliv namáhání alkalických akumulátorů na jejich parametry." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217856.
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This master's thesis deals with alkaline battery characteristics and it has special consideration of nickel-cadmium cells. There are three main experimental parts in this paper. First one is concerned with positive electrode materials properties and is aimed to investigate impact of magnesium ions formed into nickel hydroxide electrode structure. Second part deals with battery charging/discharging and response measurement tool design. National Instruments hardware PXI modules for data acquisition was used and program in LabView environment was made. Last one is concerned with nickel-cadmium cell properties changes during increased temperature stressing. Investigation of cell self-charge changes during lithium hydroxide addition into electrolyte was made.
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Kopecký, Filip. "Možnosti využití odpadních slévárenských písků." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216991.
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Considering increasing manufacture of metallic materials made in foundries increases also production of waste foundry sands. Foundry sands that remain after moulding and can not be reused in the prouction process anymore are usually not recycled nowadays and in the better cases they are clasified as a fill materials. These secondary raw materials are produced in relatively big amounts. Thats why is apropriate to search for their effective reuse. One of the possibilities is using of this materials in buliding industry. Thanks to their constitution and properties we can consider the possibilties of an alkaline activation, additional source to alkalit activated systems or like part of refractories.
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Moore, M. A. "The effect of lithium hydroxide on the nickel hydroxide electrode." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379735.
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Brumbaugh, Daniel Robert. "The evolution of modular adaptation : experimental studies of dispersal and growth in the marine colonial hydroid, Aglaophenia struthionides /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5233.
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Charles, E. A. "The effects of cobalt hydroxide addition on the nickel hydroxide electrode." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254070.
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Navrátil, Jan. "Určení vlivu iontů ve struktuře hydroxidu nikelnatého." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218391.
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Diploma thesis is involved in basic properties of nickel materials for alkaline accumulators. Practical part deals with measuring of nickel hydroxides by cyclic voltametry. Next practical part is above measuring and optimalization various proportion of nickel and cobalt in layer made by electrodeposition on nickel electrodes.
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Pavlík, Ondřej. "Neutralizace kyselých roztoků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230828.
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The present thesis is concerned with neutralization of acid groundwater after the hydrochemical uranium mining in the area of Stráž pod Ralskem. In the thesis is briefly described progression of the hydrochemical uranium mining and follow-up negative impacts on the environment. There is described the technology involved in its disposal. This is followed by the design calculation of major apparatus technology associated with neutralization of acid solutions. Output of technology is determined by the mass balance. The results are the main dimensions of the apparatus, mechanical parts and electric power each device.
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Fahy, Eoin. "Polyketide derived metabolites from the marine hydroid Garveia annulata." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27071.
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The marine hydroid Garveia annulata is a small, brightly colored coelenterate whose crude methanol extracts exhibit potent antibacterial and antifungal activity. The compounds responsible for this biological activity were purified and characterised as a series of related 1-[4H]-anthracenone derivatives. Twenty one metabolites have been isolated and their structures were elucidated by using a combination of spectral analysis, chemical interconversions, synthesis and single crystal X-ray diffraction analysis.
The structure of garveatin A (77), the major metabolite, was determined via a series of NMR experiments and by an X-ray diffraction analysis of its enol triacetate 87. Garveatins B (88), C (93) and D (96) share a common carbon skeleton with 77.
The garvin family represents a different polyketide folding pattern as seen in garvin A (124) and garvin B (126.) which contain an n-propyl group and a delta lactone functionality, respectively. Both the garveatins and the garvins contain oxidized analogs in the form of 2-hydroxy derivatives, 9,10 quinones and C2,2' dimers. NMR analysis and optical rotation experiments indicate that the C2 position of the 2-hydroxy compounds is racemic.
Garvalones A (137) and B (141) represent the corresponding 2-(3-oxobutyl) derivatives of garvins A and B respectively. They occur as pairs of C2 epimers. Their structures were confirmed by spectral comparison with 2-(3-oxobutyl) garveatin A (140) which was synthesised from 77.
Annulins A (144) and B (148) have degraded anthracene skeletons and they appear to be products of garveatin B metabolism.
All four families of G. annulata secondary metabolites appear to be produced by straightforward polyketide biogenesis. Different folding patterns of a putative nonaketide precursor account for all the structures elaborated. These polyketides represent the first examples of this type of metabolism in coelenterates.Science, Faculty of
Chemistry, Department of
Graduate
11
Lengheden, Annelie. "Periodontal implications of calcium hydroxide treatment." Stockholm : Dept. of Oral Diagnosis, Karolinska Institutet, 1994. http://books.google.com/books?id=zfJpAAAAMAAJ.
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Mavis, Bora. "Homogeneous Precipitation of Nickel Hydroxide Powders." Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Science ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2003. http://www.osti.gov/servlets/purl/822049-urdfie/native/.
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Thesis (Ph.D.); Submitted to Iowa State Univ., Ames, IA (US); 12 Dec 2003.Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2111" Bora Mavis. 12/12/2003. Report is also available in paper and microfiche from NTIS.
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Ibrahim, Ahmed Abdellatif Hamed. "Jambe Humanoïde Hydraulique pour HYDROïD." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLV038.
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Le corps humain a toujours été une source d’inspiration pour les ingénieurs et les scientifiques de tous les domaines dans le monde entier. L’un des sujets les plus intéressants de la dernière décennie a été les robots humanoïdes. Les robots humanoïdes représentent les systèmes robotiques les plus complexes. Ils offrent une plus grande mobilité dans les terrains accidentés et non structurés que les véhicules à roues normaux. À l’avenir, les robots humanoïdes devraient être employés pour une variété de tâches dangereuses dans des domaines tels que les opérations de sauvetage, l’assistance aux personnes âgées, l’éducation et le déminage humanitaire. Le travail réalisé dans cette thèse est réalisé sur le robot hydraulique humanoïde HYDROïD, un humanoïde à commande hydraulique avec 52 degrés de liberté actifs, conçu pour exécuter des tâches très dynamiques comme la marche, la course et le saut. robot puisque les actionneurs hydrauliques ont un excellent rapport poids/puissance et absorbent naturellement les pics de force d’impact lors des différentes activités. L'objectif de cette thèse est de contribuer au développement des mécanismes robotiques de la cheville et du genou avec une dynamique élevée. Un nouveau mécanisme de cheville est développé afin de pallier les inconvénients des performances réalisées avec l’ancien mécanisme de cheville d'origine. Des taux de fuite et de frottement plus faibles sont obtenus en plus d’une optimisation de pression pour les articulations de la cheville. De plus, une nouvelle solution pour optimiser le poids des actionneurs hydrauliques est appliquée sur le mécanisme du genou du robot.Une telle solution comprend l’utilisation de la technologie des matériaux composites légers pour atteindre un poids et une performance optimisés pour le joint. Afin d’appliquer des méthodologies de contrôle sur les mécanismes de la cheville et du genou, un modèle géométrique inverse pour les deux mécanismes est présenté. Le contrôle de position est utilisé pour contrôler les angles des articulations de la cheville et les mécanismes du genou. Enfin, les conclusions et les perspectives d’avenir sont présentées dans le dernier chapitreHuman body has always been an inspiration for engineers and scientists from all fields all over the world. One of the most interesting topics in the last decade was humanoid robots. Humanoid robots represent the most complex robotic systems. They provide greater mobility in rough and unstructured terrain than the normal wheeled vehicles. In the future, humanoid robots are expected to be employed for a variety of dangerous tasks in fields like rescue operations, assisting elderly people, education and humanitarian demining. The work achieved in this dissertation is performed on the humanoid hydraulic robot HYDROïD. It is hydraulically actuated humanoid featuring 52 active degrees of freedom and is designed to perform highly dynamic tasks like walking, running and jumping. Hydraulic power was chosen for this robot since hydraulic actuators have an excellent power to weight ratio and naturally absorb impact force peaks during different activities. The objective of this dissertation is to contribute toward the development of ahighly dynamic robotic ankle and knee mechanisms. A new ankle mechanism islooked for in order to tackle the drawbacks raised by the performances achievedwith the original old ankle mechanism. Lower leakage and friction rates areachieved in addition to a pressure optimization for the ankle joints. Moreover, anew solution for optimizing the weight of hydraulic actuators is applied on theknee mechanism of the robot. Such solution includes the usage of light compositematerial technology to achieve optimized weight and performance for the joint.In order to apply control methodologies on the ankle and knee mechanisms,inverse geometrical model for the both mechanism are presented. Position controlis used to control the joints angles of the ankle and the knee mechanisms. Finally,the conclusions and the future perspectives are presented in the last chapter
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Morse, Valerie Jane. "The regulation and origin of bioluminescence in the hydroid obelia." Thesis, Cardiff University, 2013. http://orca.cf.ac.uk/53880/.
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There are many questions associated with the understanding of the origin and regulation of bioluminescence. A key question underlying this thesis was why coelenterazine evolved as the most common marine luciferin. Another problem addressed was the coelenterazine source of the bioluminescent hydroid Obelia, which is unknown. Coelenterazine is an integral part of Obelia’s photoprotein, triggered by Ca2+. The thesis also investigated the uncertainty over how Ca2+ enters Obelia’s photocytes. Obelia is considered to have four species, but they have been misidentified. Green fluorescent protein (GFP) acts as a fluor in Obelia producing green light. The selective advantage of this green bioluminescence requires confirmation. Results showed that Obelia geniculata cultures rapidly lost their bioluminescence, indicating Obelia requires a dietary supply of coelenterazine. Adding coelenterazine to Obelia briefly restored its bioluminescence. Levels of obelin dropped in Obelia geniculata cultures. Obelia longissima had a lower level of coelenterazine and bioluminescence than Obelia geniculata. Coelenterazine was detected in species living on Obelia and, three non luminous species of copepod. A range of species were identified in zooplankton, as possible coelenterazine sources. Ratios of obelin to apoobelin changed in older colonies. The problem of misidentification of Obelia species was solved by utilising the fluorescent patterns of Obelia’s photocytes. GFP was recorded for the first time in the hydrotheca and tentacles of Obelia dichotoma. Fluorescence maxima for Obelia geniculata and Obelia dichotoma iv were different. GFP in Obelia was found to photobleach far slower than GFP in EGFP. This supports the hypothesis that Obelia has a molecular mechanism which protects its GFP from photobleaching. Light emission from Obelia geniculata was different from Obelia longissima. This suggests that the mode of entry of Ca2+ into the photocytes of these two species is different. To investigate the exact pathway by which initial stimulation of Obelia causes Ca2+ to enter the photocytes, experiments were conducted using K+ channel blockers. The potassium ion channel blockers tetraethyl ammonium chloride and 4-aminopyridine both produced a bioluminescent response in Obelia geniculata. This suggested that the pathway included K+channels. In a polar solvent coelenterazine produced low chemiluminescence, which increased with increasing luciferin concentration. Human albumin and BSA increased this effect. This supported the solvent cage hypothesis that bioluminescent proteins originally evolved as primitive oxygenase enzymes.
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Rovnaníková, Markéta. "Studium a modelování karbonatace betonu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-233351.
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The corrosion of steel reinforcement is probably the most frequent type of degradation of reinforced concrete structures. Reinforcing bars are protected from corrosion by a thin iron oxide layer which is formed on their surface due to a high alkalinity of the surrounding concrete. Corrosion may start when this layer is destroyed (i) either by chloride ion penetration (when the concentration of dissolved chloride at the depth of the reinforcing steel exceeds a critical value) or (ii) by a reduction in the pH value of pore solution to values below 9.5. Such a reduction in alkalinity is the result of carbonation of the Ca(OH)2 in the concrete mass, i.e. of its reaction with the atmospheric CO2. The main aim of this work is an experimental investigation and modelling of carbonation process. The effect of relative humidity, curing period and replacement of Portland cement by supplementary cementing materials (SCM - fly ash, blast furnace slag and metakaolin) on carbonation process has been studied. Calcium hydroxide content in the presence of SCM and their pozzolanic activities have been also determined. Furthermore, lots of parametric studies and comparison of carbonation models have been provided. The software tools based on the introduced models and considering the input data to be statistically independent random variables have been described and used for other parametric studies.
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Řihák, Lukáš. "Vliv aditiv na vlastnosti elektrodových hmot pro alkalické akumulátory." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217860.
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This thesis is involved in basical properties of electrode materials for alkaline accumulators. This thesis describes the possibilities of capacity stabilisation of nickel electrode to be stable for highest number of cycles. Thesis also consider modification of properties of electrode materials on the base of nickel hydroxide by using dopes (aluminum, manganese). Measuration proceeded on the thin film electrodes created by electrodeposition. Measuration of properties of electrodes proceeded by cyclic voltammetry and frequency analyzis.
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Růžička, Tomáš. "Vliv iontů hliníku ve struktuře hydroxidu nikelnatého na vlastnosti elektrod." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218707.
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This master's thesis is concerned with the influence of aluminate ions added in various concentrations into the structure of nicel hydroxide that creates Ni-Cd accumulators positive electrode active mass basis nowadays. Nicel hydroxide occurs in two basic modifications ? and ß. Nowadays used ß modification reaches low capacity in comparison with ? modification. The disadvantage of ? modification is its instability and gradual degradation to ß modification. The aim of this diploma paper is to select the optimal amount of aluminate additives into the structure of nicel hydroxide with regard to electrochemical efficiency, stability, and degradation degree of the accumulated layer.
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Fusek, Petr. "Nové elektrodové struktury pro alkalické akumulátory." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218936.
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Master´s thesis is focused on development of electrodes used in alcaline accumulators, by using new kinds of materials and compounds. Basic possitive eletrode was made of nickel, on this electrode were applied new layers of Ni(OH)2 by using the method called electrodeposition. For electrodeposition was used solution with Ni(NO3)2 in diverse concentrations. Later on, this material was enriched with aluminium admixtures to increase stability of alfa modification in Ni(OH)2. These concentrations were measured and analysed in diagrams. For measurement was used device Biologic. The diagrams were commented with recommendations for production use in accumulators.
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Janečka, Marek. "Vliv uhlíkových materiálů na kladnou elektrodu Ni-Cd akumulátorů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219496.
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Master’s thesis is deals with the effect of carbon additives on the positive electrode in the NiCd batteries. It examines whether the positive electrode material enrichment of carbon additives to achieve improved internal parameters of conductivity and better contact with the electrode materials in a discharged. Galvanostatic cycling and electro-chemical impedance spectroscopy (EIS) are used for evaluation of graphite aditives.
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Chladil, Ladislav. "Studium jevů limitujících životnost sekundárních článků Ni-Zn." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-233640.
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This dissertation is focused on the study of selected additives and their effect on positive and negative electrodes of Ni-Zn secondary cells. The first group of additives consists of the inorganic compounds that reduce zinc oxide solubility and thus prevents shape changes of the zinc electrode. The second group contains organic additives that have the beneficial effect of dendrite growth prevention. All additives were examined in relationship to their compatibility with the positive electrode and to their effect on the zinc electrode dendrites inhibition, hydrogen evolution and corrosion inhibition. Moreover, the study of decomposition kinetics of supersaturated zincate solution with the first group of additives was performed. Finally, a short study of pulse regime charging mode with regard to dendrites inhibition was performed and evaluated.
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Masue, Yoko. "Adsorption, desorption, and stabilization of arsenic on aluminum substituted ferrihydrite." Texas A&M University, 2004. http://hdl.handle.net/1969.1/3343.
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Because of As toxicity, the complexity of its chemistry, and the recent lowering of the maximum contaminant level of As in municipal drinking water, there has been considerable interest for improved methods to remove As from water. Although Al and Fe hydroxides have been extensively studied as adsorbents for As removal during water treatment, coprecipitated Al:Fe hydroxides have received only minimal attention. The theoretical and experimental feasibility of coprecipitated Al:Fe hydroxide systems were evaluated by studying their mineralogy, stability, and As adsorption and desorption behavior.
The broad XRD peaks revealed that Al was substituted into the ferrihydrite structure and that this was the only major product up to about a 2:8 Al:Fe molar ratio. Gibbsite and bayerite were identified when Al content was higher. The rate of recrystallization of ferrihydrite into goethite and hematite was significantly reduced as Al substitution was increased.
In general, adsorption capacity of both AsV and AsIII decreased with increase in Al:Fe molar ratio; however, similar AsV adsorption capacities were observed with Fe and Al:Fe hydroxides with Al:(Al+Fe) molar ratios < 0.20. Both AsIII and AsV adsorption isotherms were effectively described by Langmuir and Freundlich equations. Adsorption maxima of AsV on Fe and Al:Fe hydroxides were observed at pH 3 to 7, and that of AsV on Al hydroxide was observed at pH 5.2, with significant decreases in adsorption with increase and decrease in pH. Adsorption maxima of AsIII decreased by approximately 4 % for each 10 % increase in Al substitution up to 5:5 Al:Fe molar ratio. Adsorption maxima of AsIII on Fe and Al:Fe hydroxides were observed at pH 8 to 9. AsIII adsorption on Al hydroxide was negligible. Counterion Ca2+, compared to Na+, enhanced the retention of AsV, especially at pH > 7. Counterion concentration did not significantly affect AsV adsorption. Though phosphate desorbed both AsV and AsIII from all Al:Fe hydroxides, quantitative desorption was never observed.
The results of this study indicate the possible utility of coprecipitated Al:Fe hydroxide in wastewater treatment. Based on adsorption/desorption behavior and stability of the Al:Fe hydroxide product, the preferred Al:Fe molar ratio was 2:8.
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Tronolone, Valquiria Baddini. "Estudo faunístico e da distribuição das hidromedusas (Cnidaria, Hydrozoa) da região compreendida entre Cabo Frio (RJ) e Cabo de Santa Marta Grande (SC), Brasil." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-09102008-134819/.
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O Brasil possui uma extensão de costa marítima de mais de 9.200 km. Contudo, os componentes vivos presentes em suas águas costeiras e neríticas são parcamente conhecidos em termos taxonômicos, biogeográficos e ecológicos. Embora constitua um dos principais grupos de predadores pelágicos, seja abundante e de dimensões relativamente grandes, o plâncton gelatinoso é normalmente subestimado nos estudos de plâncton. A classe Hydrozoa é um dos grupos de invertebrados gelatinosos mais bem representados e comuns no plâncton. Dentre os trabalhos sobre hidromedusas, somente alguns abrangeram áreas extensas da plataforma continental brasileira, embora coleções oriundas de campanhas oceanográficas, como as realizadas pelo Instituto Oceanográfico da Universidade de São Paulo (IO-USP), estejam disponíveis para estudo. O objetivo do presente é inventariar as espécies de hidromedusas oriundas de duas campanhas oceanográficas realizadas pelo IO-USP na plataforma continental entre Cabo de Santa Marta Grande (SC) e Cabo Frio (RJ) (Plataforma Continental Sudeste - PCSE), nos anos de 1991 e 2001: Sardinha 1 e PADCT 2. A composição da fauna foi analisada quanto à diversidade de espécies e distribuição geográfica. Os dados foram interpretados procurando-se inferir correlações na distribuição das espécies com as massas de água características da região (Água Costeira AC; :Água Tropical AT; Água Central do Atlântico Sul ACAS). Dados brutos de distribuição também foram utilizados em uma Análise de Parcimônia de Endemicidade (PAE), no intuito de averiguar possíveis áreas de endemismo das espécies. Nas 155 amostras analisadas foram encontradas 51.808 espécimes de hidromedusas, identificados em 20 morfotipos: 10 Anthoathecata, 5 Leptothecata, 3 Trachymedusae e 2 Narcomedusae. Tanto a diversidade quanto a abundância das espécies foram menores nas amostras referentes à campanha PADCT 2 (figuras 2.2 a 2.5) quando comparadas com as da campanha Sardinha 1. Todas as espécies já haviam sido registradas para a costa brasileira, no entanto, algumas tiveram suas distribuições geográficas ampliadas. Liriope tetraphylla e Aglaura hemistoma foram as espécies mais freqüentes e abundantes nas amostras das campanhas Sardinha 1 e PADCT 2, respectivamente. As distribuições geográficas de algumas espécies mostram-se associadas, como Aglaura hemistoma e Corymorpha gracilis; Solmundella bitentaculata e a co-ocorrência do par Aglaura hemistoma-Liriope tetraphylla; e Turritopsis nutricula e Proboscidactyla ornata, estas últimas co-ocorrem sobretudo quando abundantes. O relativo baixo número de espécies de hidromedusas encontrado no presente trabalho pode ser conseqüência do método de amostragem utilizado, o qual não visava o plâncton gelatinoso. No entanto, entre os 20 táxons identificados encontram-se as espécies mais freqüentes registradas para a PCSE, como Aglaura hemistoma, Liriope tetraphylla, Rhopalonema velatum, Solmundella bitentaculata e Turritopsis nutricula. Algumas espécies apresentam relação com a presença predominante de ACAS seguida por AC: Turritopsis nutricula, Niobia dendrotentaculata, Proboscidactyla ornata, Solmundella bitentaculata e Corymorpha gracilis. Enquanto que a maioria dos exemplares de Liriope tetraphylla e Eucheilota duodecimalis,esteve associada à presença de AC. Aglaura hemistoma e Rhopalonema velatum estiveram relacionadas à ACAS ou AT+ACAS, respectivamente. A Análise de Parcimônia de Endemismo (PAE) destaca duas áreas, a primeira majoritariamente compreendida entre as isóbatas de 50 e 200 m, apresenta predomínio de ACAS em suas estações de coleta, com a presença Bougainvillia carolinensis e Dipurena sp. e o predomínio de abundância de Corymorpha gracilis, Ectopleura dumortieri, Niobia dendrotentaculata, Proboscidactyla ornata. A segunda apresenta grande abundância de Rhopalonema velatum e localiza-se principalmente a leste da isóbata de 200 m, praticamente acompanhando a distribuição das estações com AT como massa de água principal e ACAS como secundária.Brazil has an extensive marine coast of over 9.200 km. However, the taxonomical, biogeographical and ecological knowledge of the organisms present in coastal and neritic waters is scanty. Although the gelatinous plankton constitutes one of the main groups of pelagic predators, is abundant and relatively large, in size, it is usually underestimated in number and importance by the traditional sampling methods. Hydrozoa are one of the most numerous and common groups in this planktonic community. Among the works on hydromedusae, only some included extensive areas of the Brazilian continental shelf, although sampling of oceanographic expeditions, as the ones accomplished by the Instituto Oceanográfico of the Universidade de São Paulo (IO-USP), are available for study. The goal of this study is to survey the hydromedusae species collected by two oceanographic expeditions by the Brazilian vessel carried out by IO-USP along the continental shelf between Cabo Frio (RJ) and Cabo de Santa Marta Grande (SC) (South Brazil Bight - SBB), in 1991 and 2001: Sardinha 1 and PADCT 2. The diversity and geographic distribution of the hydromedusae fauna were analyzed. Data were interpreted trying to infer correlations in the distribution of the species with the characteristic water masses present in the area (Coastal Water - CW; Tropical Water - TW; South Atlantic Central Water - SACW). The distribution data were also used in a Parsimony Analysis of Endemicity (PAE), to verify possible endemic areas of the species. From the 155 samples a total of 51,808 hydromedusae specimens were found, belonging to 20 species/morphotypes: 10 Anthoathecata; 5 Leptothecata; 3 Trachymedusae; 2 Narcomedusae. The diversity and abundance of the species were lower in the samples of PADCT 2 when compared to Sardinha 1. All of the species had already been recorded for the Brazilian coast; however, some had their geographical distributions enlarged. Liriope tetraphylla and Aglaura hemistoma were the most frequent and abundant species in the samples of the Sardinha 1 and PADCT 2, respectively. There are indications that the geographical distributions of some species are associated, as Aglaura hemistoma and Corymorpha gracilis; Solmundella bitentaculata and the pair Aglaura hemistoma-Liriope tetraphylla; Turritopsis nutricula and Proboscidactyla ornata, the last association usually occurring when both species are abundant. The relative low number of hydromedusae species found in SBB can be consequence of the sampling method, which did not aim at the gelatinous plankton. However, among the 20 identified species/morphotypes are the most frequent species already recorded for SBB, as Aglaura hemistoma, Liriope tetraphylla, Rhopalonema velatum, Solmundella bitentaculata and Turritopsis nutricula.. Some species distributions are associated to specific water masses like Turritopsis nutricula, Niobia dendrotentaculata, Proboscidactyla ornata, Solmundella bitentaculata and Corymorpha gracilis in a mixture of SACW and CW. Most individuals of Liriope tetraphylla and Eucheilota duodecimalis were related to the exclusive presence of CW, while the majority of Aglaura hemistoma and Rhopalonema velatum individuals were associated with SACW or TW+SACW, respectively. Two areas were identified in a Parsimony Analysis of Endemicity (PAE), the first located between 50 and 200 m deep and predominance of SACW, with the presence of Bougainvillia carolinensis, Dipurena sp. and the predominance in abundance of Corymorpha gracilis, Ectopleura dumortieri, Niobia dendrotentaculata, and Proboscidactyla ornata. The second area was characterized by high abundance of Rhopalonema velatum, being located east of the 200 m bathymetric line, along the occurrence of TW (main water mass) and SACW (secondary water mass).
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Liauw, Christopher Mark. "Influence of surface modification of aluminium hydroxide on the processing and mechanical properties of aluminium hydroxide/polypropylene composites." Thesis, Manchester Metropolitan University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359468.
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Sezgiker, Korhan. "Production Of Nano Alumoxane From Aluminum Hydroxide." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611533/index.pdf.
Full textAbstract:
Alumina (Al2O3) is one of the most widely used engineering ceramic. It can be used in a wide range of applications like electrical/thermal insulation, wear resistance, structural refractories, cutting tools, abrasives, catalyst carriers and coatings. A traditional ceramic process has several steps (i.e. powder synthesis and processing, shape forming, drying, organic burnout and densification). Accessing powders with sizes in the range of a couple of micrometers down to several tens of nanometers is considered critical in attaining higher densities in the final ceramic bodies. Besides since significant shrinkage can be observed in the thermal treatment steps due to the excessive use of additives (e.g. binders, solvents and plasticizers) in the powder processing and forming steps, it is important to take remedies that would increase the solids loading in the initial mixtures. In addition, most of the conventional additives and solvents used in these steps are toxic and it is necessary to replace them with the environmentally benign aqueous-based alternatives.
Alumoxanes could be used as a benign aqueous-based alternative to be used as a ceramic precursor or an agent. They are a group of compounds that have nano sized boehmite cores encapsulated with the organic groups used in its production steps.
In this research work, alumoxane nano particles which can be used as precursors for nano-alumina were developed starting from aluminum trihydroxide. As a preconditioning step, grinding was applied to decrease the aluminum hydroxide particle size (≤
60 &
#956
m) to submicron sizes. This process was followed by the glycothermal ageing step, and organic derivative of boehmite was obtained. The amorphous particles thus obtained were further treated mechanochemically in a high energy ball mill with organic chemicals like acetic acid, methoxy acetic acid, stearic acid and L-lysine. After this step the observed sizes of the particles were as low as 10-100 nm. The effects of organic molecules used in each step were studied by FTIR spectroscopy and their effectiveness in exfoliation of hydroxide layers were identified with dynamic light scattering from processing solutions dispersed in aqueous medium. Moreover, in each step, structural analyses were carried out by XRD.
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Padovani, Michela. "Thiophosphates : Co(III) and hydroxide catalysed hydrolysis." Thesis, University of Sheffield, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401241.
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Markland, Charles Ivor. "Novel aspects of layered double hydroxide chemistry." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:a3494026-6f43-4696-9ff4-7e3040fe7958.
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A number of different aspects of the chemistry of layered double hydroxides and similar materials have been explored in this thesis. The intercalation chemistry of these compounds, in both aqueous and mixed solutions, has been explored to synthesise over forty new hybrid layered materials by ion-exchange and rehydration-reconstruction methods. The host used include both previously-reported layered hydroxide compounds, and novel host materials synthesised by the extension of heterogeneous reactions of solid oxides. The synthesis of these novel materials provides insights into the factors that control the compatibility of the metal ions that may form hydrotalcite-like structures, in addition to providing compounds that may act as the precursors of catalysts and other functional materials. The new intercalation compounds synthesised show interlayer distances ranging from 7.1Å to 23.6Å, and demonstrate a variety of interlayer alignments as determined by powder X ray diffraction, dependent upon both the metallic content and the degree of hydration of the host compound. The anionic contents of the interlayer regions have been further characterised through infra-red spectroscopy, elemental microanalysis, solid-state NMR and thermogravimetric analysis techniques. The mechanism and kinetics of the release of the intercalated anions from the hosts have been studied in situations approximating their real-world applications, and the degree of release quantified by UV/Visible spectroscopy. Both the rates and mechanisms of anion release have been found to be dependent on the anion, the host, the temperature and the solution into which the anions are released; as such, the release timescales of the anions may be fined tuned through modifications of the host materials. In addition, an explanation has been suggested for the observed change in mechanism observed in instances of release in which the host compound is in only partial contact with the release medium.
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Massaro, Fernanda Cristina. "Estudos ecotoxicológicos com Hydra viridissima (Cnidaria: Hydrozoa)." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-25072006-134025/.
Full textAbstract:
As hidras são os principais representantes de água doce do filo Cnidaria, e quando são expostas a substâncias tóxicas podem manifestar mudanças graduais na estrutura corporal, cuja expressão permite determinar as doses de efeitos letais e sub-letais de uma substância tóxica. No presente estudo, a espécie nativa Hydra viridissima foi cultivada em condições laboratoriais, determinando-se o crescimento populacional e individual da espécie, o tempo de duplicação da população e o tempo de geração da mesma. Além disso, esta espécie foi submetida a testes de toxicidade aguda com as substâncias dicromato de potássio e sulfeto de sódio. Testes de toxicidade também foram realizados com amostras ambientais de água e/ou sedimento de reservatórios do estado de São Paulo, visando a utilização desta espécie como organismo-teste para estudos ecotoxicológicos. A taxa de crescimento individual (k) foi de 0,43; o comprimento máximo da coluna das hidras foi de 2,53 mm e o tempo de geração foi, em média, de 6,6 '+ OU -' 1,5 dias. Para as condições de cultivo a taxa intrínseca de crescimento populacional de H. viridissima foi de 0,0468 (r) e o tempo de duplicação da população de 14,8 '+ OU -' 2,63 dias. A faixa de sensibilidade de H. viridissima ao dicromato de potássio situa-se entre 2,8 mg/L e 4,3 mg/L, com valor médio de 3,55 mg/L, sendo que esta espécie é mais sensível a esta substância do que algumas espécies que já são amplamente utilizadas em testes de toxicidade, incluindo a espécie Hydra attenuata. Nos testes de toxicidade realizados com o sulfeto de sódio estabeleceu-se que a faixa de sensibilidade para esta espécie situa-se entre 17,76 mg/L e 26,08 mg/L, com uma 'CL IND.50'-96h de 21,92 mg/L, e observou-se uma diminuição ou perda de toxicidade desta substância durante o período de realização dos testes. As amostras de água e de sedimento dos reservatórios do Lobo (Broa), de Barra Bonita e de Promissão não causaram toxicidade às hidras, enquanto que o sedimento do reservatório de Rasgão foi tóxico. Concluiu-se que a espécie H. viridissima é de fácil cultivo em laboratório, tem bom desempenho em cultivo nas condições testadas e sofre progressivas modificações morfológicas sob condições de toxicidade, sendo, portanto, um potencial organismo-teste para estudos ecotoxicológicosHydras are the main freshwater representatives of phylum Cnidaria, and when exposed to toxic substances they can display gradual changes in the body structure, whose expression allows determining the lethal and sub-lethal doses of a toxic substance. In the present study, the native species Hydra viridissima was cultured in the laboratory in order to determine its population and individual growth, the time of duplication of the population and its generation time. This species was also submitted to acute toxicity tests with the reference substances potassium dichromate and sodium sulfide, and also to toxicity tests with samples of water and/or sediment of reservoirs of the state of São Paulo, aiming to use this species as organism-test for ecotoxicological studies. The main results were an individual growth rate (k) of 0.43; the maximum length of the hydra column was 2.53 mm and the generation time averaged 6.6 '+ OU -' 1.5 days. This species presented an intrinsic rate of population growth (r) of 0.0468 for the adjusted curve and a time of duplication of the population of 14.8 '+ OU -' 2.63 days. H. viridissima has a sensitivity range for potassium dichromate varying between 2.8 mg/L and 4.3 mg/L, with a mean value of 3.55 mg/L. This species is more sensible to this substance than other species widely used in toxicity tests, including Hydra attenuata. The sensitivity range of H. viridissima to sodium sulfide varies between 17.76 mg/L and 26.08 mg/L, with a 'LC IND.50'-96h of 21.92 mg/L. A reduction or loss of toxicity to this substance was observed during the test accomplishment. The water and sediment samples of Lobo, Barra Bonita and Promissão reservoirs were not toxic, nevertheless the sediment of Rasgão reservoir was toxic to the hydras. It was concluded that H. viridissima is easy to culture in the laboratory, has a good performance in the culture conditions tested and suffers gradual morphological changes under toxic conditions, being, therefore, a potential test-organism for ecotoxicological studies
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Louw, Linda-Ann. "The synthesis of aluminium hydroxide and oxyhydroxide." Master's thesis, University of Cape Town, 1993. http://hdl.handle.net/11427/9564.
Full textAbstract:
Includes bibliographical references.Beta alumina is a ceramic with the ability to conduct certain ions. It is conventionally formed through the high temperature solid state reaction of α-alumina with soda and lithia, which results in a mixture of β- and β"-alumina phases. To maximise the amount of β"-alumina formed, a second heat treatment step is required. Beta alumina may also be synthesised directly from the various aluminium hydroxide ( Al(OH)₃ ) and aluminium oxyhydroxide (AIOOH) polymorphs. The particular oxygen sublattice of the starting material is critical in determining which phases of beta alumina are formed. Boehmite and bayerite are known to yield pure β"-alumina. In this investigation, the differences in structure and the identification of the polymorphs is discussed. A review of the methods of synthesis and concomitant mechanisms of reaction proposed in the literature are presented. Of these, the synthesis of boehmite and bayerite are investigated experimentally. Attempts to synthesise boehmite at ambient conditions resulted in the formation of pseudoboehmite, and confirmed that boehmite can only be formed by the introduction of a hydrothermal step. However, it was possible to form bayerite at ambient conditions by sμnple chemical reaction. Control of the reaction pH and the removal of inhibiting ions were found to facilitate the formation of well crystallised bayerite. Although the factors governing the successful synthesis of bayerite need further investigation, the possibility of a direct synthesis route for β"-alumina has been demonstrated. Finally, the synthesis of β"-alumina by the solid state reaction of the hydroxide and oxyhydroxide polymorphs was successfully completed.
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Schibeci, Mark. "Hydroxide speciation in highly alkaline aluminate solutions." Thesis, Schibeci, Mark (1998) Hydroxide speciation in highly alkaline aluminate solutions. Honours thesis, Murdoch University, 1998. https://researchrepository.murdoch.edu.au/id/eprint/50269/.
Full textAbstract:
A detailed investigation of the behaviour of concentrated MOH/MAl(OH)4 solutions in 4 M MCI media, where M+ = Na+, K+ or Cs+, has been made by high precision hydrogen electrode potentiometric titrations. The performance of the electrodes in each of the I = 4 M (M(Cl)) media was established up to high hydroxide concentrations (up to 2 M) by strong acid-strong base titrations.
The data confirm previous observations in NaC104 media that there is a release of OH- with increasing [OH-] and [Ai(OH)4-]. More significantly this release appears to be independent of the cation in the medium. These effects are consistent with competitive ion pairing interactions or the possibility of the formation of an aluminium-containing dimer.
Raman spectra of MOH solutions were not fully consistent with literature results but do indicate the presence of significant ion pairing, although no ion pairing constants could be derived.
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Pica, Daniela. "Morphology and ecology of Stylasteridae (Cnidaria, Hydrozoa)." Doctoral thesis, Università Politecnica delle Marche, 2013. http://hdl.handle.net/11566/242735.
Full textAbstract:
La famiglia Stylasteridae è una della due famiglie di idroidi a presentare uno scheletro calcareo
chiamato coenosteum.
Gli Stylasteridae sono idroidi polimorfici e presentano due tipi di polipi che escono lungo il
coenosteum attraverso dei pori. La distribuzione dai pori lungo la colonia e la loro forma sono
caratteristiche strettamente legate al genere. I polipi di una colonia sono connessi attraverso una
fitta rete di canali cenosarcali che permea l’intero scheletro.
Durante il dottorato, la morfologia dello scheletro degli Stylasteridae è stata studiata per la prima
volta attraverso l’utilizzo della microtomografia computerizzata a raggi X (Xray μCT). E’ stato
dimostrato come questa tecnica non distruttiva risulti molto utile nello studio della morfologia
scheletrica ed inoltre è stato osservato come l’approccio integrato tra questa tecnica e il tradizionale
tecnica SEM permetta uno studio più approfondito e dettagliato della tassonomia di questa famiglia.
Infatti, i risultati ottenuti attraverso la combinazione di queste due tecniche permettono
l’identificazione di caratteri morfologici che altrimenti potrebbero venire male interpretati o
addirittura potrebbero passare inosservati.
Lo studio dei primi stadi di crescita di alcune specie di Stylasteridae ha mostrato come in
quest’ultime il primo step sia la formazione di un ciclosistema primario, anche nel caso in cui da
adulte esse presentino una differente distribuzione di pori. Questi dati hanno portato a due ipotesi: 1.
ciclosistema come distribuzione tipica dei pori dall’antenato di questa famiglia; 2. ciclosistema
come miglior tipo di distribuzione per la protezione del primo gastrozoide da parte dei dattilozoidi.
Il presente studio riporta, inoltre, la dettagliata descrizione della modalità di crescita di due specie di
Distichopora, dalla formazione del ciclosistema primario fino alla formazione della colonia adulta
che presenta una distribuzione di pori in file.
Sono stati condotti degli studi anche dal punto di vista della riproduzione. Uno studio preliminare
ha consentito di capire in dettaglio la morfologia e lo sviluppo dei gonofori di quattro specie di
Stylasteridae indonesiani. Inoltre, attraverso uno studio ultrastrutturale, sono stati descritti alcuni
step della spermatogenesi, fino al differenziamento degli spermatozoi, in una specie di Distichopora.
Lo studio effettuato in merito alla fauna associata ha messo in luce la simbiosi di alcune specie di
Stylasteridae con i cirripedi lepadomorfi. Inoltre, è stato dimostrato come gli Stylasteridae,
nonostante il loro scheletro calcareo, non siano facilmente attaccabili da parte delle spugne
perforatrici.Stylasteridae is one of the two hydroid families having hard, calcareous skeleton. The stylasterids are polymorphic hydroids having two different kinds of polyps lodged in pores. The distribution of the pores over the coenosteum and their shapes are features strictly related to the genera. All the polyps of a colony are connected by a network of coenosarcal canals that densely perforate the coenosteum. The morphology of the stylasterid skeleton was finely investigated for the first time using the X-ray computed microtomography technique (μCT). The utility of this technique for the non-destructive study of coral morphology was showed, demonstrating the benefit of the integrated analysis of pictures produced by X-ray μCT and the traditional SEM techniques in coral taxonomy. Indeed the combined results allow the identification of morphological characters that otherwise could be misidentified or even could pass unnoticed. The observation of post-larval specimens belonging to several species that when adult show pores arranged in rows, in cyclostystems or without coordination revealed that they invariably produce a primary cyclosystem. These data lead to the hypothesis that the cyclosystem represents the pore organisation of the family ancestor or that this organisation provides greater protection to the young gastrozooid by the dactylozooids. The present study reports also the first detailed description of the growth stages of two Distichopora species showing the formation of a primary cyclosystem and the description of the growth process from primary cyclosystem to adult pore organisation. From the reproductive point of view a preliminary survey was carried out about the morphology of the reproductive structures and the development of the gonophores of four Indonesian species. In addition for the first time a detailed description, at ultrastructural level, of some steps of the spermatogenesis up to spermatozoa differentiation in a Distichopora species was provided. The study of the associated fauna showed the first evidence of stylasterids associated to goose barnacles. Moreover the survey concerning the association between sponges and stylasterid corals reveled no specific association and generally the recorded sponges bore only the dead portion of the colonies not enveloped by living epithelium and lacking the coenosteal stolon network.
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Hofírková, Linda. "Lomová houževnatost kompozitu s polymerní matricí." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228671.
Full textAbstract:
This diploma work deals with relationship between composition and mechanical properties of polymeric composite with polypropylene matrix and magnesia hydroxide as a filler. The influence of content of filler (20,40,60 w.%) and temperature (-30°C +60°C) on dynamic fracture toughness is observed. The regresion function describing the dependence of studied mechanical properti on temperature for all experimental materials where found. Experimental data were confront with data gained on the same materials then 10 years ago and influence of time on mechanical properties of follow - up composites is evaluate.
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Dumitru, Paul. "Influence of surface modification of magnesium hydroxide on the processing and properties of a thermoplastic elastomer/magnesium hydroxide composite." Thesis, Manchester Metropolitan University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326440.
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Raymond, Carole Lesley. "Coatings for magnesium hydroxide fillers in polyethylene compounds." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/26868.
Full textAbstract:
This study has been carried out to determine the effect of filler coatings on the physical and mechanical properties of medium density polyethylene (MDPE) filled with a fine grade of magnesium hydroxide filler. The filler coatings applied are of varying aliphatic chain length, the shortest being decanoic acid (C1O), and the longest being an acid-terminated PE, Mw=5000g/mol. The other coatings applied were stearic acid (C18), a commonly used coating, and behenic acid (C22). This selection of coatings provided a comparison of the effect of fatty acid chain length, with the acid group of the functionalised PE providing a similar reaction with the filler surface as the fatty acids, and also being of sufficient length. and compatibility to interact with the MOPE matrix. The coating process has been studied to fully characterise the interaction between Mg(OH)2 filler surface and the acid group. It has been shown using FTIR DRIFT and transmission spectroscopy that the reaction is ongoing, with no unreacted acid present in the system. The temperature and coating cycle time necessary to produce a full reaction between acid group and filler surface has been determined for each coating type. XPS analysis carried out on the coated fillers has shown that the coating thickness is of the same order as the calculable fully extended chain length, demonstrating that the aliphatic chains are normal to the surface of the filler.
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Geswindt, Theodore Earl. "The reactions of osmium (VIII) in hydroxide medium." Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/960.
Full textAbstract:
Spectrophotometric techniques were used to elucidate the discrepancies surrounding the reduction of osmium tetroxide by several primary alcohols in a hydroxide matrix. In contrast to the documented literature, this reaction was observed to occur in two consecutive reaction steps. Geometrical and computational analysis of kinetic data revealed that the reaction proceeds by the following reaction model: Os(VIII) + RCH2OH Os(VI) + RCHO Os(VIII) + Os(VI) Os2(VII) k1 k+2 k-2 The conditional rate constants and molar extinction coefficients were calculated using custom written software. A hydride transfer mechanism, coupled with the synchronous removal of the hydroxyl proton of the alcohol, was postulated. The complexation between osmium(VIII) and osmium(VI) was investigated. Mole ratio titrations and mole fraction plots show that at pH 14.3 a 1:1 complexation occurs between osmium(VIII) and osmium(VI). The equilibrium constants and molar extinction coefficients calculated by these methods were found to be consistent with the parameters obtained from the reduction of osmium tetroxide by primary alcohols at pH 14.3. The formation of a mixed oxidation state dimeric osmium complex (denoted Os2(VII)) has been proposed. Key words: Spectrophotometric techniques, osmium tetroxide, osmium(VIII), primary alcohols, osmium(VI).
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Tam, Kawai 1969. "Neutralization of an acidic effluent using magnesium hydroxide." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=26426.
Full textAbstract:
Metal and acid containing effluents generated by industry are most commonly treated with lime which neutralizes the acid and precipitates the dissolved metals. The resulting sludge contains gypsum which has a high water content and requires large landfill volumes. It is therefore desirable to find a neutralizing agent which has a good neutralizing capacity and a dense precipitate which can be easily dewatered at low cost. A dense, fast settling sludge would also reduce the cost of the process and the volume to be landfilled. Magnesium hydroxide has been examined in this research as a neutralizing agent for a simulated iron-containing acidic solution. The effects of reaction temperature, dosage, rate of Mg(OH)$ sb2$ addition, and recycle on the neutralization of acidic iron solutions with magnesium hydroxide were studied. Magnesium hydroxide was found to be an effective precipitating agent removing over 98.3% of the iron from solution and an effective neutralizing agent exhibiting a buffering effect which stabilized the pH between 8.8 to 9.7 even with overtreatment. Observation of precipitate colour suggested that at lower pH values (2.2 to 4.3) ferric hydroxide was formed in the sludge whereas at higher pH values (9.3 to 9.7) the sludge consisted primarily of ferrous hydroxide. Increasing reaction temperatures from 10$ sp circ$C to 25$ sp circ$C did decrease reaction time but had insignificant effects on sludge production or characteristics. However, slow Mg(OH)$ sb2$ addition to the acidic iron solution as well as the use of a recycle both resulted in the production of larger sludge particles which resulted in a denser, fast-settling sludge.
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Jordan, Stephanie Louise. "The characterization and reactivity of calcium hydroxide surfaces." Thesis, Brunel University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296213.
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Lakin, Nicholas Mark. "Electronic and microwave spectroscopy of indium(I) hydroxide." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259963.
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Gondal, Shahla. "Carbon dioxide absorption into hydroxide and carbonate systems." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-27125.
Full textAbstract:
In the global warming scenario, a literature review on carbon dioxide capture technologies shows that CO2 capture by chemical absorption seems to be the immediately viable route for sustainable energy supply in near future. The technology for chemical absorption is available and has been practiced in the industry. Development and identification of optimal absorbents for absorption is required to employ it on the scale required for CO2 capture and to minimize the energy penalty of capture. Hydroxide and carbonate systems have been used for absorption of CO2 from the beginning of the 20th century in different industrial processes. Though the use of hydroxides and carbonates remained persistent in special applications but the use of these systems in industrial gas cleaning units decreased after the introduction of alkanolamines as absorbents. During the last two decades, hydroxide and carbonate systems have regained interest in post combustion CO2 capture by absorption. Potentially low energy requirements for the capture process based on hydroxide and carbonate systems and being environment friendly are advantages over the energy intensive amine based CO2 capture solvents and environmental issues arising from degradation of amines. This thesis contributes to the kinetics and equilibrium of CO2 absorption into hydroxide and carbonate systems. The measured experimental data on CO2 absorption and physical solubility of CO2 (from N2O solubility using N2O analogy) into these systems, in addition to vapor liquid equilibrium (VLE) data were used to evaluate the activity based kinetics of the reaction of CO2 with hydroxyl ion (OH-) containing Li+, Na+ and K+ counter ions. To study the kinetics of the CO2 reaction with hydroxyl ion is important not only for hydroxide and carbonate systems but it is significant as this reaction occurs in all alkaline systems including alkanolamines. The density and N2O solubility data into aqueous hydroxides and blends of hydroxides with carbonates containing Li+, Na+ and K+ counter ions were experimentally determined. The measured density data were compared with an empirical density model available in the literature. The measured N2O solubility data were used for the refitting of parameters in an extensively used solubility model available in the literature for up gradation to wider ranges of temperature and concentration. The measured N2O solubility data and VLE data collected from the literature were simultaneously regressed using an in-house equilibrium model to determine the interaction parameters in the Electrolyte-NRTL model. The determined Electrolyte- NRTL parameters were subsequently used for the estimation of liquid phase activities of CO2 and OH- in the systems containing Li+, Na+ and K+ counter ions. The kinetics of aqueous hydroxides and blends of hydroxides with carbonates containing Li+, Na+ and K+ counter ions were experimentally measured using a string of discs contactor (SDC). The measured data were used for the parameter optimization in a widely used kinetics model available in the literature to a broader range of temperature. Finally, the activity based kinetics of the CO2 reaction with OH- were determined using the measured kinetics data and the calculated liquid phase activities of CO2 and OH- in the aqueous solutions containing Li+, Na+ and K+ counter ions.
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Mangano, Valentina. "Studies of some properties of hydroxide-catalysis bonds." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30938/.
Full textAbstract:
Jointing materials is an inevitable step in the fabrication of many high performance optical devices. Today there is an increasing demand, both from industry and academic research, for reliable techniques for jointing of optical components which can be performed simply and inexpensively, where the bonds possess high strength and precision with low mechanical loss. Several methods of bonding have been defined and employed over time. Currently, the most common techniques of bonding are optical contacting, diffusion, epoxy and glass frit. Each of these techniques has positive aspects which make them appropriate for a range of applications, but not ideal in cases where a thin optically transparent and mechanically strong joint between optical compounds is required. Hydroxide-catalysis bonding is an interesting candidate in such cases: it has already been demonstrated to have excellent performance with respect to mechanical stability, precision and strength in numerous applications, such as in space systems, optics and gravitational wave detectors. At present, there are not many papers that talk exhaustively about the optical properties of hydroxide-catalysis bonding. Most of the time, the published results are closely dependent on requirements imposed by the experiment that is being conducted. Since there are a lot of interesting potential applications and increasing industrial interest in usage of hydroxide-catalysis bonding, it is important to develop techniques to characterise the optical properties of these bonds. In this thesis, a non-destructive technique for measuring the optical properties of hydroxide-catalysis bonding is reported. More specifically, the bond refractive index and thickness are determined from reflectivity measurements. By applying this method, it will be possible to understand how the optical properties and chemistry of a hydroxide-catalysis bond vary when different bonding solutions and substrate materials are used and, consequently, to tailor better the bonds to various utilisations of interest. Sodium silicate solution at different concentrations with water and potassium hydroxide solution are used to bond fused silica and sapphire substrates. Curing at room temperature and at 100 °C for eight hours is chosen to study the influence of temperature on the properties of a hydroxide-catalysis bond. It was found that the bond optical reflectivities are less than 1% for fused silica samples and less than 10% for sapphire samples and they decrease over time. Bond refractive indices start from a value close to the refractive index of water and approach the refractive index of fused silica as the cure proceeds. Bond thicknesses cured at room temperature decrease over time plateauing at a more or less constant value, different for each case studied (about a few hundred nanometres), whereas bond thicknesses cured at high temperature seem to increase over time (less than about 400 nanometres).
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Mergler, Bianca Isolde. "Enterocyte uptake of nanoparticulate iron(III) oxo-hydroxide." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610413.
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Green, Vicki C. "CO2 Recovery by Scrubbing with Reclaimed Magnesium Hydroxide." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378196688.
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Coelho, Helena Isabel Soares Dinis. "Microphytobenthos vs Hydrobia: trophic coupling in estuarine environment." Doctoral thesis, Universidade de Aveiro, 2010. http://hdl.handle.net/10773/3632.
Full textAbstract:
Doutoramento em BiologiaOs estuários são ambientes complexos, biologicamente diversos e muito importantes no que respeita à produtividade primária. As zonas intertidais destes ecossistemas são ocupadas por organismos que possuem uma elevada capacidade de sobrevivência e adaptação face às variadas e rápidas alterações nos factores ambientais (tais como temperatura, salinidade, conteúdo hídrico, etc.). As cadeias tróficas com origem no ecossistema estuarino bentónico são essencialmente herbívoras, regulando o fluxo de energia desde o fundo sedimentar e através do ecossistema. Nas áreas estuarinas intertidais a produção primária é essencialmente suportada pelo microfitobentos (MPB). Estas comunidades de microalgas bênticas constituem uma importante fonte de matéria orgânica e são por si só a principal fonte alimentar para as populações de Hydrobia. Neste contexto, a interacção MPB - Hydrobia é um modelo-chave na investigação da cadeia trófica estuarina de origem bentónica, actuando como um importante canal de transporte de energia para os níveis tróficos superiores, especialmente se considerarmos que Hydrobia é uma importante presa para peixes, aves e caranguejos. O presente estudo tem por objectivos gerais: i) a investigação do controlo ambiental (particularmente da luz e do teor em água do sedimento) e endógeno na migração vertical do MPB e ii) a identificação e potencial utilização de marcadores tróficos (pigmentos e ácidos gordos) úteis à investigação da interacção MPB – Hydrobia em laboratório e em condições naturais, considerando a existência de uma elevada plasticidade trófica por parte da Hydrobia e a elevada densidade populacional que estes organismos podem apresentar. A primeira fase de investigação resultou na comparação do papel dos estímulos ambientais e do controlo endógeno nos padrões de comportamento migratório vertical do microfitobentos, demonstrando a existência de um controlo essencialmente endógeno na formação e desintegração do biofilme superficial. A regulação e manutenção da biomassa à superfície do sedimento são claramente controladas pela variação dos factores ambientais, em especial da luz, cuja presença é essencial à formação total do biofilme microalgal à superfície do sedimento intertidal. Foi proposta uma nova abordagem metodológica com vista à estimativa nãodestrutiva do teor de água de sedimentos intertidais vasosos , possibilitando o estudo da influência da acção do vento no conteúdo hídrico dos sedimentos e o consequente impacto da dessecação na comunidade microfitobêntica. Observou-se que a dessecação provoca efeitos limitantes não só na biomassa superficial mas também na actividade fotossintética dos biofilmes microfitobênticos, conduzindo à diminuição da produtividade primária. No que respeita à dinâmica trófica da interacção MPB - Hydrobia foi estabelecido o uso do pigmento feoforbide a, quantificado nas partículas fecais da fauna, como marcador trófico que permite estimar a quantidade de biomassa de microalgas (clorofila a) incorporada pelos organismos animais.Para tal foi investigada e comprovada a existência de uma relação significativa entre a concentração de feopigmentos excretados e a concentração de clorofila a ingerida. Estes estudos foram desenvolvidos numa primeira fase à escala diária, considerando os efeitos dos ciclos sazonais, dia-noite e maré, e depois com a validação em condições naturais, numa escala mensal. A taxa de ingestão média de indivíduos de H. ulvae varia ao longo do dia, com o máximo em torno dos períodos diurnos de maré baixa, o que pode estar relacionado com a disponibilidade de MPB. As taxas de ingestão (TI) de H. ulvae variam ainda em função da estação do ano (TI verão > TI primavera) e em função da densidade de indivíduos (> densidade, < ingestão). Verificou-se um efeito negativo na concentração de clorofila disponível após herbívoria independentemente da densidade de indivíduos. Finalmente, a comparação dos perfis de ácidos gordos de H. ulvae provenientes de diferentes habitats com os perfis de potenciais fontes alimentares permitiu demonstrar que os ácidos gordos são ferramentas úteis na identificação do habitat ocupado por estes organismos. No entanto, apesar da ocupação de diferentes habitats e da integração de múltiplas fontes de produção primária na sua dieta foram sempre observados significativos níveis de ácidos gordos específicos de microalgas (em particular diatomáceas), reforçando o papel importante das comunidades de microalgas bênticas na dieta das populações de H. ulvae.
Estuaries are biologically diverse and form complex environments, which play an important role on the global primary productivity of aquatic environments. Intertidal areas of estuaries are inhabited by organisms with a strikingly capability to survive and to be adapted to frequent and fast changes in several environmental factors (such as temperature, salinity, water content, etc.). Grazing food chains are common in intertidal mudflats regulating the flow of nutrients and energy from the bottom throughout the estuarine ecosystem. Within intertidal estuarine areas the primary production was predominantly supported by microphytobenthos (MPB). These benthic microalgae assemblages are an important source of organic matter and are a main food source for Hydrobia populations. The MPB - Hydrobia interaction is a key model for the estuarine grazing food chain, acting as a significantly channel of energy to higher trophic levels, since Hydrobia is an important prey item for fish, birds and crabs. The present work addressed: i) the environmental (namely light and sediment water content) and the endogenous control of the vertical migration by microphytobenthos, and ii) the identification and the potential use of trophic markers (pigments and fatty acids) to establish this relationship under laboratory and natural conditions, considering that H. ulvae showed significant trophic plasticity and that mud snails could reach extremely high densities. The role of exogenous cues and endogenous control of the patterns of vertical migratory behavior of intertidal MPB biofilms were compared, showing that the formation and disintegration of the biofilm is endogenously-controlled. The regulation and maintenance of the microalgal biomass at the sediment surface is dependent on the variation of environmental factors, namely light, which is essential for the full formation of the MPB biofilm. A new methodological approach was proposed to estimate the water content of muddy intertidal sediments, enabling the study of the influence of wind on the hydric level of the sediment and the consequent impact of desiccation on the MPB biomass. This investigation showed that desiccation might be responsible to cause important limiting effects on biomass and photosynthetic activity of intertidal MPB biofilms, reducing the primary productivity. Regarding the trophic dynamics of the interaction MPB - Hydrobia, it was established the use of the pigment pheophorbide a, present on Hydrobia ulvae faecal pellets, as a trophic marker to estimate the amount of microalgal biomass incorporated, as chlorophyll a, by benthic macrofauna. A significant relationship between egested pheopigments and ingested chlorophyll a was investigated and validated. These studies were firstly developed on a daily scale, considering the effects of seasonal, tidal and day-night cycles, followed by a validation under natural conditions, on a monthly scale. The mean ingestion rate of H. ulvae individuals varied along the day, with the maximum around the diurnal low tide periods, which may be related with MPB availability. H. ulvae mean ingestion rate (IR) also varies seasonally (IR summer > IR spring) and depending on mud snails density (> density, < ingestion). There was a negative effect on chlorophyll concentration available after grazing, independently of H. ulvae density. Finally, the comparison of fatty acid profiles of mud snails from different habitats with the ones from potential food sources allowed identifying fatty acids as a useful tool to indicate H. ulvae habitat. Although the occupation of different habitats and the integration of multiple primary food sources on mud snails diet, significant inputs of fatty acids specific of microalgae (namely diatoms) were always found, which reinforce the important role of MPB on the diet of H. ulvae populations.
FCT; FSE - SFRH/BD/23720/2005
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Harrison, Hollie. "The electrodialysis of lithium sulphate to lithium hydroxide." Thesis, Harrison, Hollie (2018) The electrodialysis of lithium sulphate to lithium hydroxide. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/40456/.
Full textAbstract:
There is currently an increasing demand for lithium-ion batteries, and therefore a push within the industry to produce lithium hydroxide. Electrodialysis has been shown to be a promising new technology for producing lithium hydroxide.
A three-compartment batch electrodialysis cell was constructed, utilising an anionic exchange membrane and a cationic exchange membrane. This cell was constructed in order to produce lithium hydroxide from lithium sulphate salt. The cell was run under multiple different conditions to observe the effect that they would have on the recovery of lithium within the lithium hydroxide of the catholyte compartment within the cell. The initial pH of the solution, the temperature of the system, the initial concentration of lithium sulphate and the residence time within the cell were all tested in separate experiments in order to observe how they would influence the system and the production of lithium hydroxide.
The results of this study indicated that by decreasing the initial concentration of the lithium sulphate within the cell, the lithium recovery is dramatically increased, at 30 wt.% lithium sulphate, 18.3% of the lithium is recovered within 4 hours into the catholyte solution as lithium hydroxide. At 5 wt.% lithium sulphate, 81.2% of the lithium is recovered within 4 hours into the catholyte as lithium hydroxide.
The results also suggest, the rate of production of lithium hydroxide is fastest when the residence time within the cell is reduced, however, a longer residence time within the cell will increase the lithium recovery. A 4-hour test at 30 wt.% of lithium sulphate yielded a 23.1% lithium recovery within the catholyte solution. When this residence time was doubled, the recovery was increased to 37% lithium within the catholyte as lithium hydroxide.
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Kaddissy, Josiane. "Hydrogen production from irradiated aluminum hydroxide and oxyhydroxide." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS253/document.
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Dans le cadre de l’entreposage et du stockage des colis de déchets nucléaires et du transport de combustibles usés, nous nous sommes intéressés par l’étude de la production d’hydrogène de deux produits de corrosion de l’aluminium : l’hydroxyde d’aluminium (Al(OH)3) et l’oxyhydroxyde d’aluminium (AlO(OH)).La production du dihydrogène par irradiation de ces matériaux a été étudiée en fonction de la taille et de la structure que ce soit à température ambiante ou après. Afin d’avoir une meilleur compréhension des mécanismes de production de ce gaz, les défauts créés par irradiation ont été caractérisés en utilisant la Résonnance Paramagnétique Electronique (RPE). Différentes sources d’irradiation ont été utilisées comme le rayonnement Gamma, les électrons accélérés et les ions lourds. Dans un second temps, l’effet de l’hydratation de surface des matériaux a été également étudié. Enfin, l’effet de la présence d’impuretés sur la production de H2 a été brièvement étudiéDihydrogen production is a critical issue for the current management of nuclear wastes. One potential source of hydrogen generation is the radiolysis of hydrated mineral phases encountered in the nuclear waste transportation and storage casks. We chose to study aluminum hydroxide (Al(OH)3) (Bayerite) and oxyhydroxides (AlOOH) (Boehmite) as model compounds. The determination of molecular hydrogen production was evaluated with respect to structure and particle size at room temperature and after annealing. In order to have a better understanding of the mechanisms and to identify the precursors of molecular hydrogen, we studied the irradiation defects and their stabilities using Electron Paramagnetic Resonance (EPR). The effect of adsorbed water and structural water on the molecular hydrogen production was studied. Different radiation sources were used such as Gamma radiation, electron beam radiations and heavy ions. In the last part, preliminary results related to the impact of impurities on hydrogen production are presented
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Špičák, Petr. "Studium hydroxidů a oxidů kovů ve vodných roztocích." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-233539.
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This dissertation work deals with analysis of nickel hydroxide phases, their oxidation compounds, their stability and degradation mechanisms of electrochemically more active alpha phase on standard beta phase. The active material was prepared by both methods, electrodeposition and chemical precipitation. Main analysis method was Electrochemical Quartz Crystal Microbalance in combination with common analytical methods (cyclic voltammetry, potenciometry) can resolute between alpha and beta phases and quantitatively describe differences in main reaction by monitoring mass changes in the active material. Poor stability of the ?-Ni(OH)2 were improved by adding cations with valence two three and four into the structure instead of Ni atoms. The most important role plays cobalt and its hydroxide. Totally new way is to use titanium in combination with other cations. In electrolyte the most significant addition is LiOH, which has beneficial influent on cycle ability, stability in strong alkaline medium and cycle life.
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Iqbal, Muhammad Ahsan. "Layered double hydroxide based smart protective coating systems." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/302211.
Full textAbstract:
Corrosion protection of aluminum and its alloys is a challenging subject to widen the service life of material and its industrial usage. Numerous protective measures have been employed for the corrosion protection of aluminum alloys. Chromate based coatings system was in use for a long time to protect the light metals alloys, but after the ban on Chromates based coating (2017) in European Union due to strict health and safety rules and regulations, there is a need to develop environmentally friendly, greener coating systems to functionalize aluminum surface and to provide sufficient chemical and electrochemical stability against the aggressive environment and can possess multifunctional properties. The present study investigates the designing of the "Layered double hydroxide (LDHs)" based system for the protection of AA6082 alloy, which until now has given not much attention. LDHs demonstrate unique characteristic which helps to obtain special microstructure to attain multi-functional properties along with improved corrosion resistance properties. The novel environmentally friendly “Layered double hydroxides” (LDHs) thin films were synthesized, through chemical conversion approach, directly on the aluminum AA6082 substrates, and precisely characterized by various physical and electrochemical approaches. The defining of proper synthetic conditions for the synthesis of LDH is problematic due to the influence of certain parameters which made an impact not only on the structural properties of the LDHs but also on the anticorrosion behavior of LDH. This study focused on the thorough investigation of the optimization of synthetic conditions for LDHs and their effect on LDH assembly, surface morphology, thickness, interaction with corrosion inhibitors to control the corrosion resistance properties.
The first step of the work is to control the synthetic parameters to obtain unique LDHs structural geometries for the development of anti-corrosion thin films. The addition of a complexation agent i.e. urea, ammonium hydroxide was also introduced to obtain distinct surface morphologies. Various LDHs classes were developed on the aluminum substrate in that scenario, for example, MgAl-LDH, ZnAl-LDH, NiAl-LDH, CaAl-LDH, and a detailed comparative study is reported about the dependency of structural- electrochemical relationships. The aim was to find the ideal films' properties, which leads to widening the potential window of corrosion resistance films in the defined electrolytes. To analyses high-temperature applications, calcination of developed MgAl-LDHs is investigated to understand the effect of thermal treatments on the LDHs structure, basal spacing, intercalated anions, and its effects on corrosion resistance properties.
The second part of the thesis is focused on the modification of the LDHs. Initially, graphene is introduced inside the LDHs network due to graphene chemical inertness and electrochemical characteristics. A thorough investigation is reported about the interaction of graphene with LDHs, and the ability of graphene to tune the properties of LDH for the designing of improved protective LDHs films. Specifically, the research focused on the use of graphene to seal the micropores of LDHs films to promote barrier properties and explore the graphene interaction with the LDHs. Overall, the impedance modulus of the films was compared with the results of virgin LDHs and the efficacy of the graphene-based LDH system is described.
In the third part of the thesis, cerium modified LDHs are developed on the anodic AA6082 substrate to understand the self-healing characteristic of the modified LDHs based system and their long-term protective ability. Rare earth elements found to have a significant inhibiting effect and are the object of considerable scientific interest, exhibiting nontoxic nature. Conceptually, the cerium modified LDH grown on the anodized surface can seal the micropores of the anodized surface (improved barrier properties), while LDHs themselves provide active protection via entrapment of aggressive species and through self-healing properties. The final part of the thesis comprises the introduction of a double-doped effect, where cerium was introduced inside LDHs galleries and further doped with superhydrophobic species to obtain compact LDH multifunctional films with enhanced LDHs corrosion resistance properties. In the case of the double doped cerium-based LDHs films, the improvement in the corrosion resistance properties were observed during the long-term EIS measurements, while superhydrophobic, self-cleaning characteristics, and UV radiation impact on coating was thoroughly reported. Double doped LDHs lead to an influential increment in corrosion resistance properties, durability, and long-term stability.
Furthermore, the role of LDHs as adsorbents for the heavy metals present in drinking water is also reported. Different adsorption models are studied, and adsorption kinetics is reported to understand the adsorption behavior of LDHs against arsenic impurities. The results depicted the successful removal of arsenic from drinking water with high efficiency than traditionally used materials.
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Iqbal, Muhammad Ahsan. "Layered double hydroxide based smart protective coating systems." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/302211.
Full textAbstract:
Corrosion protection of aluminum and its alloys is a challenging subject to widen the service life of material and its industrial usage. Numerous protective measures have been employed for the corrosion protection of aluminum alloys. Chromate based coatings system was in use for a long time to protect the light metals alloys, but after the ban on Chromates based coating (2017) in European Union due to strict health and safety rules and regulations, there is a need to develop environmentally friendly, greener coating systems to functionalize aluminum surface and to provide sufficient chemical and electrochemical stability against the aggressive environment and can possess multifunctional properties. The present study investigates the designing of the "Layered double hydroxide (LDHs)" based system for the protection of AA6082 alloy, which until now has given not much attention. LDHs demonstrate unique characteristic which helps to obtain special microstructure to attain multi-functional properties along with improved corrosion resistance properties. The novel environmentally friendly “Layered double hydroxides” (LDHs) thin films were synthesized, through chemical conversion approach, directly on the aluminum AA6082 substrates, and precisely characterized by various physical and electrochemical approaches. The defining of proper synthetic conditions for the synthesis of LDH is problematic due to the influence of certain parameters which made an impact not only on the structural properties of the LDHs but also on the anticorrosion behavior of LDH. This study focused on the thorough investigation of the optimization of synthetic conditions for LDHs and their effect on LDH assembly, surface morphology, thickness, interaction with corrosion inhibitors to control the corrosion resistance properties.
The first step of the work is to control the synthetic parameters to obtain unique LDHs structural geometries for the development of anti-corrosion thin films. The addition of a complexation agent i.e. urea, ammonium hydroxide was also introduced to obtain distinct surface morphologies. Various LDHs classes were developed on the aluminum substrate in that scenario, for example, MgAl-LDH, ZnAl-LDH, NiAl-LDH, CaAl-LDH, and a detailed comparative study is reported about the dependency of structural- electrochemical relationships. The aim was to find the ideal films' properties, which leads to widening the potential window of corrosion resistance films in the defined electrolytes. To analyses high-temperature applications, calcination of developed MgAl-LDHs is investigated to understand the effect of thermal treatments on the LDHs structure, basal spacing, intercalated anions, and its effects on corrosion resistance properties.
The second part of the thesis is focused on the modification of the LDHs. Initially, graphene is introduced inside the LDHs network due to graphene chemical inertness and electrochemical characteristics. A thorough investigation is reported about the interaction of graphene with LDHs, and the ability of graphene to tune the properties of LDH for the designing of improved protective LDHs films. Specifically, the research focused on the use of graphene to seal the micropores of LDHs films to promote barrier properties and explore the graphene interaction with the LDHs. Overall, the impedance modulus of the films was compared with the results of virgin LDHs and the efficacy of the graphene-based LDH system is described.
In the third part of the thesis, cerium modified LDHs are developed on the anodic AA6082 substrate to understand the self-healing characteristic of the modified LDHs based system and their long-term protective ability. Rare earth elements found to have a significant inhibiting effect and are the object of considerable scientific interest, exhibiting nontoxic nature. Conceptually, the cerium modified LDH grown on the anodized surface can seal the micropores of the anodized surface (improved barrier properties), while LDHs themselves provide active protection via entrapment of aggressive species and through self-healing properties. The final part of the thesis comprises the introduction of a double-doped effect, where cerium was introduced inside LDHs galleries and further doped with superhydrophobic species to obtain compact LDH multifunctional films with enhanced LDHs corrosion resistance properties. In the case of the double doped cerium-based LDHs films, the improvement in the corrosion resistance properties were observed during the long-term EIS measurements, while superhydrophobic, self-cleaning characteristics, and UV radiation impact on coating was thoroughly reported. Double doped LDHs lead to an influential increment in corrosion resistance properties, durability, and long-term stability.
Furthermore, the role of LDHs as adsorbents for the heavy metals present in drinking water is also reported. Different adsorption models are studied, and adsorption kinetics is reported to understand the adsorption behavior of LDHs against arsenic impurities. The results depicted the successful removal of arsenic from drinking water with high efficiency than traditionally used materials.
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Miranda, Thaís Pires. "Faunística e distribuição geográfica de hidróides bentônicos (Cnidaria, Hydrozoa) do sudoeste do Atlântico." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-24022010-183145/.
Full textAbstract:
O aprofundamento de estudos faunísticos e taxonômicos é essencial para a inferência de áreas de distribuição geográfica e, conseqüentemente, de áreas de endemismo. Estes estudos são incipientes para o ambiente marinho, incluindo o sudoeste do Atlântico, particularmente em relação aos cnidários. Os principais objetivos deste estudo foram (1) levantar a fauna de hidróides bentônicos da região entre Cabo Frio (Brasil) e Terra do Fogo (Argentina) e (2) inferir a distribuição geográfica das espécies levantadas, buscando uma eventual caracterização de áreas de endemismo. No total, 181 morfoespécies de hidróides foram registradas, sendo que destas, 10 são registros novos para a região (Aglaophenia trifida, Antennella secundaria, Cryptolarella abyssicola, Filellum contortum, Lafoea coalescens, Lovenella gracilis, Macrorhynchia grandis, ?Nemertesia ciliata, Sertullarella leiocarpa e Zygophylax sibogae) e 9 são espécies endêmicas (Corymorpha januarii, Ectopleura obypa, Eudendrium caraiuru, Hydractinia uniformis, Lytocarpia canepa, Parascyphus repens, Plumularia insignis, Ralpharia sanctisebastiani, Symplectoscyphus magellanicus) para a área. A riqueza de espécies teve uma pequena diminuição com o aumento da latitude e diminuiu drasticamente em águas mais profundas (abaixo das isóbatas de 100 e 1000m). A análise de PCA demonstrou que os substratos Algae, Hydrozoa, Mollusca, Porifera e Rocha apresentaram os maiores números de ocorrência de morfoespécies de hidróides. A análise de cluster resultou na delimitação de três grupos de fauna: (1) brasileiro costeiro, (2) uruguaio-argentino e (3) oceânico contínuo por toda a área amostrada. Em relação às áreas de endemismo, as análises com o NDM-VNDM resultaram em duas principais áreas endêmicas costeiras para o litoral do Brasil (entre 22-24°S 43-46°W e entre 26-29°S 48-49°W), sendo que a metodologia PAE resultou em quatro áreas endêmicas para a região de estudo: (1) áreas costeiras contínuas para o Brasil ou Argentina; (2) áreas costeiras e contínuas entre o Brasil e Argentina; (3) áreas oceânicas contínuas entre Cabo Frio e Terra do Fogo; (4) áreas restritas à região do rio da Prata. Nossos resultados revelaram que a correspondência entre as faunas de profundidade brasileira e de regiões mais rasas do litoral argentino pode estar relacionada com o regime de frentes oceânicas atuantes no sudoeste do Atlântico. Além disso, análises incluindo exclusivamente espécies de hidróides que produzem medusa em seus ciclos de vida resultaram em áreas de endemismo mais restritas à costa em relação às espécies que formam somente gonóforos fixos. Estes resultados contradizem o paradigma clássico que associa a presença de medusa com a alta capacidade dispersiva das espécies.Increasing on faunistic and taxonomic knowledge is essential for reliable inferences on the geographical distribution and, consequently, on areas of endemism. This knowledge is incipient for the marine realm, including southwestern Atlantic, and particularly poor for cnidarians. The main goal of this study was (1) to survey the fauna of benthic hydroids from the region between Cabo Frio (Brasil) and Terra do Fogo (Argentina), and (2) to infer the geographic distribution of the surveyed species, aiming to propose areas of endemism. A total of 181 morphospecies of hydroids was recorded, 10 species are new records (Aglaophenia trifida, Antennella secundaria, Cryptolarella abyssicola, Filellum contortum, Lafoea coalescens, Lovenella gracilis, Macrorhynchia grandis, ?Nemertesia ciliata, Sertullarella leiocarpa e Zygophylax sibogae) and 9 are endemic species (Corymorpha januarii, Ectopleura obypa, Eudendrium caraiuru, Hydractinia uniformis, Lytocarpia canepa, Parascyphus repens, Plumularia insignis, Ralpharia sanctisebastiani, Symplectoscyphus magellanicus) for the area. Species richness slightly decreases along higher latitudes and along deeper waters (below 100 and 1000m isobaths). A PCA analyses has demonstrated that the substrata, Algae, Hydrozoa, Mollusca, Porifera and Rock showed a higher number of morphospecies of hydroids. Cluster analysis resulted in three faunistic groups: (1) Brazilian-coastal, (2) Uruguayan-Argentinean and (3) and oceanic group continuous along the entire surveyed area. Concerning areas of endemism, NDM-VNDM analyses resulted in two main coastal areas of endemism on the Brazilian coast (between 22-24°S 43-46°W and between 26-29°S 48- 49°W), and PAE resulted in four areas of endemism for the studied area: (1) coastal area in Brazil or Argentina; (2) a coastal and continuous area along Brazil and Argentina; (3) an oceanic and continuous area; (4) a Rio de La Plata area. Our results have shown that faunal affinities between Brazilian deep fauna and Argentinean shallow water fauna might be related to the marine fronts present in the southwestern Atlantic. Moreover, analyses exclusively including hydroid species with medusa in the life cycle resulted in more limited areas of endemism closer to the coast than those analyses exclusively including hydroids species with fixed gonophores. These results contradict the classical paradigm associating the presence of medusa and higher dispersive capabilities of the species.
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Shimabukuro, Vanessa. "As associações epizóicas de Hydrozoa (Cnidaria: Leptothecata, Anthoathecata e Limnomedusae): I) Estudo faunístico de hidrozoários epizóicos e seus organismos associados; II) Dinâmica de comunidades bentônicas em substratos artificiais em São Sebastião, SP." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/41/41133/tde-29082007-145731/.
Full textAbstract:
A epibiose é um fenômeno que inclui epizoísmo (organismos que utilizam animais como substrato) e epifitismo (organismos que utilizam vegetais como substrato). Especificamente para Hydrozoa, há diversos tipos de associação destes com outros animais (e.g., moluscos, crustáceos, poríferos e ascídias), em uma relação conhecida como epizoótica ou epizóica. De maneira geral, as larvas plânulas de hidróides ou outras formas de dispersão, como frústulas e pólipos desprendidos, podem fixar-se e crescer em quase qualquer animal macroscópico do bentos marinho, incluindo outros hidróides, simplesmente usando-os como um substrato conveniente. Há duas formas de expressão do epizoísmo em Hydrozoa: (1) quando os mesmos são substratos de outros animais e (2) quando eles exploram um animal como substrato. A segunda acepção proposta, em que hidróides colonizam outros animais usando-os como substrato, foi o foco deste estudo. A primeira acepção só será incluída neste estudo quando houver hidróides que utilizam outros hidróides como substrato. O estudo foi dividido em duas partes, cada uma com objetivos próprios, embora complementares no conhecimento sobre os hidróides epizóicos. A primeira parte, o estudo faunístico, objetiva primeiramente o levantamento das espécies de hidróides epizóicos e da fauna utilizada como substrato por meio do estudo de coleções de museus e materiais coletados em pontos do litoral de Santa Catarina e São Paulo, e de registros citados na literatura. A segunda parte, o estudo de dinâmica da comunidade de hidróides epizóicos, objetiva investigar as associações com substratos animais quanto à sazonalidade de ocorrência, reprodução e ocupação por hidróides epizóicos, por meio de experimento em campo com placas de recrutamento no canal de São Sebastião. No estudo faunístico foram encontradas 117 espécies epizóicas que utilizaram como substratos representantes de duas classes de Porifera (Hexactinellida e Demospongiae), 211 espécies que utilizaram como substratos representantes de duas classes de Cnidaria (Anthozoa e Hydrozoa), 143 espécies que utilizaram representantes de duas classes de Mollusca (Bivalvia e Gastropoda), 57 espécies que utilizaram como substratos representantes de duas ordens de Polychaeta (Aciculata e Canalipalpata), 72 espécies que utilizaram representantes de duas classes de Crustacea (Maxillopoda e Malacostraca), 103 espécies que utilizaram representantes das classes Gymnolaemata e Stenolaemata de Bryozoa e 51 espécies que foram encontradas sobre representantes de três ordens de Ascidiacea (Aplousobranchia, Phlebobranchia e Stolidobranchia). Os aspectos biológicos das associações foram discutidos nos capítulos referentes a cada tipo de substrato animal. Já no estudo de dinâmica das comunidades bentônicas, foram caracterizados hidróides epizóicos de 25 espécies, e estes utilizaram substratos dos filos Porifera, Cnidaria, Mollusca, Arthropoda (Crustacea), Annelida (Polychaeta), Bryozoa e Chordata (Ascidiacea). Os agrupamentos de substratos encontrados na análise de correspondência parecem estar relacionados a características morfológicas dos substratos. Já os fatores biológicos e temporais influenciaram a sucessão ecológica das placas experimentais. No capítulo de considerações finais, os dados sobre epizoísmo dos capítulos de faunística e dinâmica, além de dados referentes a substratos menos freqüentes (não apresentados nesta dissertação), foram reunidos para uma análise de aspectos mais globais do epizoísmo de hidrozoários. Assim, possíveis padrões das famílias de hidróides epizóicos puderam ser definidos (em agrupamentos de especialistas, generalistas ou exclusivos de alguns substratos animais) e discutidos2.1 The associations between animal groups and species of sponges are relatively well known and described in the literature. Of all the cnidarian groups, the most diverse associations with sponges are found among the hydrozoans. In this study, 117 species of epizoic hydroids were found on two classes of sponge substrates (Hexactinellida and Demospongiae). The biological aspects of the interactions between hydrozoans and sponges were discussed in this chapter. 3.1 Many studies describe the association between cnidarians and other organisms, even other cnidarians. In this study, 211 species of epizoic hydroids were found on two classes of cnidarian substrates (Anthozoa and Hydrozoa). The biological aspects of the interactions between hydrozoans and other cnidarians were discussed in this chapter. 4.1 The Phyllum Mollusca is one of the main groups that hydrozoans have ecological associations. On soft-bottom environments, the shells are an alternative for the organisms that need hard susbtrates to settle and grow. In this study, 143 species of epizoic hydroids were found on two classes of mollusc substrates (Bivalvia and Gastropoda). The biological aspects of the interactions between hydrozoans and molluscs were discussed in this chapter. 5.1 The polychaetes are abundant in different habitats and can be associated with many animals, even hydroids. In this study, 57 species of epizoic hydroids were found on two orders of polychaetes substrates (Aciculata and Canalipalpata). The biological aspects of the interactions between hydroids and polychaetes were discussed in this chapter. 6.1 The crustacean can be used as substrates, being their bodies and appendages overgrown by hydroid polyps. Another form of association found in the literature is indirect: the polyps grow over the gastropod shells occupied by hermit crabs. In this study 72 species of epizoic hydroids were found using two classes of Crustacea (Maxillopoda and Malacostraca) as substrates. The biological aspects of the interactions between hydroids and crustaceans were discussed in this chapter. 7.1 The bryozoan colonies grow on many substrates like rocks, algae, shells, crustaceans, ascidians, hydroids, and are important fouling members that grow on artificial substrates. However, they can also serve as substrate for other animals, even hydroids. In this study, 103 species of epizoic hydroids were found on two classes of bryozoan substrates (Gymnolaemata and Stenolaemata). The biological aspects of the interactions between hydroids and bryozoans were discussed in this chapter. 8.1 The most common commensal organisms of ascidians cited in the literature are copepods, molluscs, polychaetes, nemertines and there are records of endosymbiotic hydroids. The associations between ascidians and hydroids were listed in this study, and 51 species of epizoic hydroids were found on three orders of ascidian substrates (Aplousobranchia, Phlebobranchia e Stolidobranchia). The biological aspects of the interactions between hydroids and ascidians were discussed in this chapter. 9.1 Studies on the colonization of artificial substrates are quite common in the literature. In this study, we used ceramic panels in São Sebastião, SP, in order to observe the hydroid epizoic community and their animal substrates. Twenty-five species of epizoic hydroids were found on substrates of Porifera, Cnidaria, Mollusca, Arthropoda (Crustácea), Annelida (Polychaeta), Bryozoa and Chordata (Ascidiacea). The groups of substrates defined by the correspondence analysis seem to be related to the morphological features of the substrates, and the biological and temporal factors seem to influence the ecological succession of the experimental panels.
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Máca, Tomáš. "Modifikace hydroxidu nikelnatého pro zlepšení jeho elektrochemických vlastností v alkalických akumulátorech." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-233682.
Full textAbstract:
Commercial alkaline accumulators with positive electrode based on nickel hydroxide generally comprise beta modification of the active material at present due to its excellent stabilization of performance during electrochemical cycling. This dissertation refers to a research work accomplished by author, which has been aimed to utilization of alpha nickel hydroxide in alkaline batteries including exploration of possibilities to attain its stability in strong alkali medium of the electrolyte. I have focused my effort to elucidate reasons for its transformation tendency and to find way of their suppression.