Segui questo link per vedere altri tipi di pubblicazioni sul tema: Manganese metal.
Tesi sul tema "Manganese metal"
Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili
Vedi i top-50 saggi (tesi di laurea o di dottorato) per l'attività di ricerca sul tema "Manganese metal".
Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.
Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.
Vedi le tesi di molte aree scientifiche e compila una bibliografia corretta.
1
Ball, R. J. "Redox-geometry relationships in transition metal complexes". Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273126.
Testo completo
2
Thomas, Jaron Michael. "On Metal synthesis of Some Substituted Rhenium and Manganese Complexes". TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1225.
Testo completoAbstract (sommario):
Heterocyclic organic and organometallic compounds (i.e. polypyrrole), and their derivatives, have been of great interest for conductive polymers due to their novel properties and environmental stability as compared to their non-aromatic analogs (i.e. polyacetylene). Our current interest focus upon the potential role of metal ligand bound pyridazines as the next generation of electronic devices that utilize the metal ligands bound to organics as the semiconducting material. Pyridazine is a 6-membered aromatic ring with two adjacent nitrogen atoms. These are promising candidates for a variety of materials and commercial applications; but they are difficult to get a metal ligand to fuse to the aromatic ring.
Our recent efforts focused in attaching Rhenium and Manganese ligands/substituents (process in which is called doping) that would cause oxidation to occur to our polymer making it a p-type polymer. Since p-type polymers charge carriers leave a vacancy that does not delocalize completely. This vacancy (known as a hole) or a radical cation that only partially delocalizes over several monomeric units causing them to be structurally deformed. This deformed structure is at a higher energy than that of an undoped polymer. Typical carriers in organic semiconductors are holes and electrons in a π-orbital. So when these molecules of π-conjugated systems have a π-bond overlap (or π- stacking), electrons can move via these π-electron clouds overlapping thus causing an electrical current.
Our worked focused on the synthesis of pyridazines and their organometallic rhenium complexes and polymer research. Several aryl-substituted 5,6-fused pyridazines have been synthesized but none have been documented until this study. The main goal of the research was to fully characterize the general synthesis of furan containing organometallic complexes, [M(CO)3{η5-1,2-C5H3(CC4H3ON)(CC4H3ON)}] (M = Re or Mn) (4B). We successfully characterized the ability to attach a metal organic ligand to pyridazine though IR and NMR. However, when attempts were made to recrystallize our product, we yielded an orange-brown, block like crystal of 1,2- C5H3(CC4H3ONH)(CC4H3ON) (5) in which our metal ligand group fell off and we were left with pyridazine and inorganics. Though, we successfully got an X-ray characterization and electronic studies of compound 5 which are reported herein.
3
Javaid, Saqib. "Magnetism and electronic structure at hybrid manganese-phthalocyanine/metal interfaces". Strasbourg, 2011. https://publication-theses.unistra.fr/public/theses_doctorat/2011/JAVAID_Saqib_2011.pdf.
Testo completoAbstract (sommario):
Nous avons étudié le mécanisme d'adsorption de la molécule MnPc sur le Co(001) ou le Cu (001) et les interactions d’interface qui en découlent. Nos calculs GGA montrent que la molécule MnPc est chimisorbée sur Co et conduit à de fortes interactions magnétiques à l’interface, notamment au couplage magnétique entre la molécule MnPc et le substrat de Co, et à une polarisation magnétique induite au niveau de Fermi sur les sites N et C. En raison de la chimisorption de MnPc sur Co, l'introduction des interactions faibles de vdW n'apporte aucun changement significatif à la structure électronique d’interface. Toutefois, le calcul GGA montre que la molécule MnPc sur Cu est physisorbée en raison des interactions chimiques très faibles. Nos calculs montrent qu’à l'opposé de MnPc sur Co, les interactions vdW modifient fortement la structure électronique d’interface de MnPc/ Cu. Cela conduit à un changement significatif du mécanisme d'adsorption de MnPc sur Cu (de la physisorption à une faible chimisorption). Du point de vue de la spintronique, la polarisation de spin sur MnPc, induite et modulée par des substrats ferromagnétiques souligne la pertinence des interfaces hybrides MPc/métalferromagnétique pour l'injection de spin et le transport de spinsWe have studied the adsorption mechanism of MnPc on Co(001) and Cu(001) and the ensuing interfacial interactions. Our GGA calculations show that MnPc is chemisorbed on Co. The chemisroption of MnPc on ferromagnetic Co results in strong interfacial magnetic interactions, leading to magnetic coupling of MnPc with Co substrate and also the induction of a a net positive spin polarisation at N and C sites at EF. Due to the chemisorption of MnPc on Co, the introduction of weak vdW interaction does not bring a significant change to the interfacial electronic structure. However, MnPc on Cu is described to be physisorbed by GGA due to very weak chemical interactions at interface. In sharp contrast to MnPc/Co, the vdW interactions strongly modify the MnPc/Cu interfacial electronic structure. This leads to change of adsorption mechanism of MnPc on Cu from physisorption to weak chemisorption. From spintronics perspective, the spin polarisation on MnPc, induced and modulated by ferromagnetic substrates underscores the suitability of MPc/ferromagnetic hybrid interfaces for the efficient spin injection and spin transport
4
Rydén, Jens Olof Stefan. "Computational studies Of manganese-ligand clusters in the gas-phase and manganese atoms in graphene and metal-organic frameworks". Thesis, University of Sussex, 2011. http://sro.sussex.ac.uk/id/eprint/7400/.
Testo completoAbstract (sommario):
The work in this thesis deals with computational studies of manganese ions and atoms in the gas-phase and in the solid phase. The results are divided into three chapters, and the theory and methods used are explained and discussed in a separate theory chapter. The first results on manganese and its coordination to water and methanol molecules in the gas-phase are discussed in the light of physical properties for different ligands including water and methanol. Preferred coordination of a specific ligand type, preferred complex or cluster size as well as coordination modes are thoroughly investigated. Also discussed is stability against proton-transfer reactions for a few manganese-water and manganese-methanol clusters. The work is carried out at the HF/6- 31G(d), MP2/6-311G(d,p) and B3LYP/6-311(3df,3pd)-level of theory using the computer code Gaussian. The results presented here are in good agreement with experimental results and findings. It is concluded that mixing between 4s and 3d orbitals on the manganese atom is responsible for preference for a specific cluster size and that occupation of anti-bonding orbitals destabilizes the cluster, for a specific coordination mode. The next results are for manganese atoms in a double layer of graphite, using the computer code Aimpro. Different coordination modes are investigated as are magnetic properties upon adsorption and modification of the band structure compared to a pristine double layer of graphene. Only one case of a significantly high spin polarization is encountered, and the spin polarization on the manganese atom and the surrounding carbon atoms is investigated with Mulliken analysis. This study is in agreement with previous work in the same field, but provides a more realistic picture since a larger system is considered here. The final chapter deals with manganese atoms in metal-organic frameworks, MOFs, using the Aimpro code. Magnetic properties and binding energies for adsorption of selected molecules are discussed in this chapter. Magnetic properties are discussed using Mulliken analysis. Modification of the band structure upon coordination of these gas molecules is shown and investigated. Very few experimental results exist in this field for this structure, but its role as a potential candidate for hydrogen storage will specifically be discussed.
5
Borton, Peter Thomas. "Preparation and Characterization of Manganese Fulleride". University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1354556594.
Testo completo
6
Krueger, Kathryn Marie. "Metal fluxes across the sediment water interface in a drinking water reservoir". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90297.
Testo completoAbstract (sommario):
Elevated concentrations of iron (Fe) and manganese (Mn) in drinking water degrade water quality by affecting taste, odor, and color. Under oxic conditions (dissolved oxygen (DO) >2 mg/L), Fe and Mn are rarely present in soluble form in natural waters, as they occur as insoluble, oxidized minerals in sediments. However, the development of low DO concentrations in the bottom waters of some lakes and drinking water reservoirs during thermal stratification can lead to the reduction of oxidized, insoluble Fe and Mn in sediments to soluble forms, which are then released into the water column. In response, many water utilities have installed oxygenation systems to control metal concentrations in situ in drinking water reservoirs. However, previous research has found anoxic (DO < 0.5 mg/L) conditions still develop within sediments, even with operational oxygenation systems, allowing for the reduction and release of soluble Fe and Mn into the water column.
To examine the drivers of metal release from sediments into the water column, I conducted sediment flux chamber experiments to directly quantify Fe and Mn fluxes at the sediment-water interface of a small, eutrophic drinking water reservoir (Falling Creek Reservoir, Vinton, VA). The experiments were conducted twice during the 2018 summer stratification period (April 24 – October 21). Using the flux chambers, I measured total and soluble Fe and Mn concentrations under changing oxygen conditions over 10-day periods to calculate fluxes. Throughout the experiments, I monitored DO, oxidation-reduction potential (ORP), temperature, and pH. In addition to the direct measurements, I also estimated metal fluxes using a mass balance method, which relies on measurements of metal inputs and outputs into the bottom waters of the reservoir.
Overall, our results showed that fluxes are highly variable during the stratification period, with some periods having positive fluxes (release of metals from sediment to the water column) and some with negative fluxes (return of metals from the water column to sediment). The metal fluxes are highly sensitive to redox conditions in the water column, sediment-water interface and sediments.
Metal fluxes measured using the chambers are 91-105% higher than those estimated using the mass balance method. This difference supports result of previous work that the flux chamber method likely provides maximum values of metal fluxes as the isolated chamber water does not allow for mixing with the bottom waters. In contrast, because the mass balance method relies on water column data, results are affected by mixing and biogeochemical reactions that can remove metals from the water column; thus, flux estimates using this method likely reflect minimum values. However, when used together, these two methods provide a useful tool for constraining metal fluxes under different redox conditions and highlight the importance of measuring ORP in addition to DO. The results of this study can be used by water utilities to improve the effectiveness of engineered oxygenation systems and water quality management practices related to iron and manganese.Master of Science
In many drinking water reservoirs, elevated concentrations of metals, such as iron (Fe) and manganese (Mn), pose a challenging water quality problem. Elevated metal concentrations affect taste, color, and odor in drinking water and can be expensive to treat for. The presence of Fe and Mn in water is influenced by the oxygen concentrations in the water. When oxygen levels in the water are high, Fe and Mn are not soluble in water. However, when the oxygen levels in water are low, Fe and Mn can be released from soils, sediments and rocks into water and can thus pose a concern for drinking water quality. Many water utilities have installed systems to increase oxygen concentrations in drinking water reservoirs with the goal of maintaining low levels of metals in water supplies. However, previous research has shown that even when oxygenation systems are operational, Fe and Mn can still be released into water from the reservoir’s bottom sediments. To examine the factors that contribute to the release of metals from the sediments into the water column, I measured the rate of release of Fe and Mn from the sediments into the water column at a local drinking water reservoir (Falling Creek Reservoir, Vinton, VA). I conducted the experiments twice during summer 2018 using chambers that isolated the water immediately above the sediments. During the experiments, I monitored how Fe and Mn concentrations changed over time under different oxygen conditions. In addition to the measurements, I also used a mass balance method using water column data to estimate the metal release. Overall, results showed that release rates are highly variable during the summer months, with some periods having positive rates (releasing metals from sediments into the water column) and some with negative rates (returning metals from the water column to sediment). The metal release rate are highly sensitive to oxygen conditions in the water column, at the sediment-water interface and in the sediments. When used together, these two methods provide a useful tool for constraining metal release rates under different oxygen conditions. This research will help drinking water plant managers to improve the effectiveness of oxygenation systems and water quality management practices related to Fe and Mn. Additionally, this research will help improve the water quality for residents and can be applied to other lakes and reservoirs where metal concentrations are elevated.
7
Faulkner, Charlotte Waveney. "A study of some ruthenium(II) and manganese(I) acetylide and vinylidene complexes". Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/272793.
Testo completo
8
Bryant, Jasmine R. "Mechanistic studies of the oxidations of hydrocarbons by manganese and ruthenium transition metal complexes /". Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/8586.
Testo completo
9
Rolle, Clarence J. "Selective aerobic oxidations catalyzed by manganese(III) complexes using redox-active ligands". Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42827.
Testo completoAbstract (sommario):
Selective oxidations are important for the functionalization of compounds in organic synthesis and chemical industry. Using O2 as a terminal e- acceptor would be ideal because it is cheap and environmentally friendly, but aerobic oxidations are often prone to unselective free radical autoxidation. Recently developed palladium catalysts use O2 as a selective multi-electron oxidant for various organic transformations. Although these methods are powerful and sophisticated, the lower cost of base metals makes them attractive as potential alternatives. The challenge is to develop methods for effecting multi-electron transformations at metals that typically prefer one electron changes. To this end, the development of manganese(III) complexes containing redox-active ligands as catalysts for selective oxidase-type oxidation of organic substrates was pursued. Bis(tetrabromocatecholato) manganese(III) complexes were shown to aerobically oxidize catechols to form quinones and H2O2. This reactivity was extended to other alcohol and amine substrates. In these reactions, the non-innocent tetrabromocatecholate ligands may impart a multi-electron character to the metal. To directly probe the intermediacy of ligand-centered radicals in catalytic turnover, a series of structurally similar manganese(III) complexes with aminophenol-derived ligands were prepared and characterized. The capacity of these ligands to undergo low-energy redox changes, allowed for isolation of an electron transfer series spanning two redox states without a change in oxidation state at the metal center. The ligand-centered redox events were a key feature in aerobic homocoupling of Grignard reagents.
10
Szeinbaum, Nadia Heliana. "Role of microbial manganese respiration in the anaerobic cycling of nitrogen". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53407.
Testo completoAbstract (sommario):
Despite the environmental significance of microbial manganese reduction, the molecular mechanism of microbial manganese respiration remains poorly understood. Soluble Mn(III) has been recently found to be a dominant soluble species in aquatic systems, yet little is known about the identity of microbial populations catalyzing Mn(III) reduction in the environment nor the molecular mechanism of Mn(III) respiration. In this research, a suite of Mn(III) reduction-deficient mutant strains were isolated, including Mn(III) reduction-deficient mutant strain Mn3-1 that also displayed the ability to reduce soluble organic-Fe(III), but not solid Fe(III) oxides, demonstrating for the first time that the reduction of soluble organic-Fe(III) and solid Fe(III) oxides proceed through electron transport pathways with at least one distinct component. This work also shows that the electron transport pathway for Mn(III) reduction in S. oneidensis shares many of the electron transport components of Fe(III) and Mn(IV) reduction pathways and that Mn(IV) reduction to Mn(II) proceeds step-wise through two one-electron transfer reactions with Mn(III) as a transient intermediate. Finally, sediment incubations were carried out to enrich for NH4+ oxidizing- Mn(III) reducing consortia. The Mn(III) reducing consortium was found to be dominated by an electrogenic Ochrobactrum sp. and a Shewanella sp. The isolated Shewanella strain is able to oxidize acetate with Mn(III) as electron acceptor, an activity never observed before in a metal-reducing member of the Shewanella genus.
11
Randazzo, Paola. "Study of the regulatory network linked to metal ion homeostasis in Bacillus subtilis". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS387.
Testo completoAbstract (sommario):
Le projet de thèse concerne l’étude des réseaux de régulation en lien avec l’homéostasie des ions métalliques chez la bactérie à Gram-positif Bacillus subtilis. Les ions métalliques tels que Fe(II), Mn(II) et Zn(II) sont essentiels dans un grand nombre de processus cellulaires entant que cofacteur d’enzymes ou en tant qu’élément structural dans les protéines. Cependant, à trop hautes concentrations, ils peuvent avoir des effets toxiques en endommageant la membrane cellulaire et l’ADN ainsi qu’en inactivant la fonction de certaines protéines. De plus, en condition aérobie, B. subtilis produit du peroxyde d’hydrogène H₂O₂ qui réagit avec les ions Fe(II) pour produire des radicaux libres hautement toxiques pour la cellule. La régulation de l’homéostasie des ions métalliques doit donc être parfaitement régulée et coordonnée avec les autres processus cellulaires. J’essaie de comprendre de façon globale, via des approches expérimentales à grande échelle, les interconnexions entre les régulateurs de l’homéostasie des ions métalliques et autres voies métabolique dans Bacillus subtilisThe present doctoral thesis concerns the study of the regulatory network linked tometal ions homeostasis in the Gram+ Bacillus subtilis. Metal ions such as Fe(II), Mn(II) andZn(II) are essential for many metabolic processes, since they function as enzyme cofactors andstructural ligands of proteins. Changes in ions availability can alter activity of enzymes of thecarbon metabolism and lead to changes in gene expression. In addition, the modulation of metalion homeostasis is intimately linked with the oxidative stress response: during aerobic growth,hydrogen peroxide is generated and it rapidly reacts with ferrous iron to form ROS molecules.Hence, regulation of metal ions uptake/efflux has to be finely regulated and coordinated with othercellular processes. With the present project, I aim to understand at system’s level how Bacillussubtilis integrates the control of metal ions homeostasis with other metabolic processes
12
Cooper, Rebecca Elizabeth. "Bacterial iron and manganese reduction driven by organic sulfur electron shuttles". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54894.
Testo completoAbstract (sommario):
Dissimilatory metal-reducing bacteria (DMRB) play an important role in the biogeochemical cycling of metals. DMRB are unique in that they possess the ability to couple metal reduction with their metabolism. Microbial Fe(III) respiration is a central component of a variety of environmentally important processes, including the biogeochemical cycling of iron and carbon in redox stratified water and sediments, the bioremediation of radionuclide-contaminated water, the degradation of toxic hazardous pollutants, and the generation of electricity in microbial fuel cells. Despite this environmental and evolutionary importance, the molecular mechanism of microbial Fe(III) respiration is poorly understood. Current models of the molecular mechanism of microbial metal respiration are based on direct enzymatic, Fe(III) solubilization, and electron shuttling pathways. Fe(III) oxides are solid at circumneutral pH and therefore unable to come into direct contact with the microbial inner membrane, these bacteria must utilize an alternative strategy for iron reduction. Reduced organic compounds such as thiols are prominent in natural environments where DMRB are found. These thiol compounds are redox reactive and are capable of abiotically reducing Fe(III) oxides at high rates
S. oneidensis wild-type and ΔluxS anaerobic biofilm formation phenotypes were examined under a variety of electron donor-electron acceptor pairs, including lactate or formate as the electron donor and fumarate, thiosulfate, or Fe(III) oxide-coated silica surfaces as the terminal electron acceptor. The rates of biofilm formation under the aforementioned growth conditions as well as in the presence of exogenous thiol compounds indicate that ∆luxS formed biofilms at rates only 5-10% of the wild-type strain and ∆luxS biofilm formation rates were restored to wild-type levels by addition of a variety of exogenous compounds including cysteine, glutathione, homocysteine, methionine, serine, and homoserine. Cell adsorption isotherm analyses results indicate that wild-type is can attach to the surface of hematite particles attachment , but ΔluxS is unable to attach the hematite surfaces. These results indicate that biofilm formation is not required for Fe(III) oxide reduction by S. oneidensis
∆luxS anaerobic biofilm formation rates were restored to wild-type levels by addition of exogenous auntoinducer-2 (AI-2), a by-product of homocysteine production in the Activated Methyl Cycle. This discovery led to subsequent experiments performed to detect the production and utilization of AI-2 by wild-type and ∆luxS strains under aerobic and anaerobic conditions. AI-2 production experiments showed wild-type, but not ΔluxS, was capable of producing AI-2. The addition of exogenous S. oneidensis and Vibrio harveyi-produced AI-2 to wild-type and ∆luxS resulted in the swift depletion of AI-2 from the media. These results provide evidence that S. oneidensis can produce AI-2 and subsequently utilize its’ own AI-2 as well as AI-2 produced by other bacteria as a carbon and electron source in the absence of preferred carbon sources.
S. oneidensis produces and secretes a suite of extracellular thiols under anaerobic Fe(III)-reducing and Mn(III) and Mn(IV)-reducing conditions including cysteine, homocysteine, glutathione, and cyteamine. Exogenous thiols produced by S. oneidensis are intermediates of the Activated Methyl Cycle (AMC) and Transulfurylation Pathway (TSP). Reduced and oxidized thiols were detected, indicating that the thiols are in a constant state of flux between the reduced and oxidized forms and that the concentration of reduced thiols to its’ oxidized counterpart is indicative of the state of metal reduction by the microorganisms. Respiratory phenotypes Based on Fe(III) and Mn(IV) respiratory phenotypes observed in the AMC and TSP pathway mutants (∆luxS, ∆metB, ∆metC and ∆metY) we can infer that cysteine, glutathione, and cysteamine contribute to metal reduction by serving as efficient electron shuttling molecules, while homocysteine is critical for maintenance of the AMC, propagation of thiol biosynthesis, and maintenance of cellular metabolism via the AMC intermediate SAM. Furthermore, these findings suggest that all metal-reducing bacteria require thiol formation to reduce solid metal oxides. Direct contact mechanism is not the dominant means through electrons are transferred and metals are reduced, instead electron shuttles are the maid reduction mechanism.
13
Terrell, Matthew. "PM2.5 and Metal Exposures in Children Living Near a Ferromanganese Refinery". University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1267545519.
Testo completo
14
Caps, Valerie. "Tailored metal-oxo species on MCM-41 for catalytic oxidation reactions in the liquid phase". Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343217.
Testo completo
15
Kelly, Julie Ann. "The significance and biological/abiological interplay in Fe(III) and Mn(IV) reduction in contrasting sediments". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361079.
Testo completo
16
Sandford, Andrew Robert Brian. "Effect of manganese and nickel on the cleavage fracture strength of ferritic weld metal". Thesis, London Metropolitan University, 1990. http://repository.londonmet.ac.uk/3058/.
Testo completoAbstract (sommario):
All weld metal test pieces were produced from two commercial and six experimental 7016 type electrodes, each having different contents of manganese and nickel. These were tested in three point bending over a range of depressed temperatures in a cryostatic cell of the author’s devising. Notched samples were used to obtain values for the cleavage fracture strength. This was calculated by reference to slip line field theory from the fracture load at the test temperature where fracture was first coincident with general yielding. The commercial electrodes were first tested in the as welded condition and all eight electrodes were then tested after a heat treatment designed to give a microstructure similar to that found in re-heated weld metal. Notched and pre-cracked samples were then tested in the heat treated condition to determine KI values. Fracture surfaces were examined by scanning electron microscope and grain size measurements made by optical microscopy. Lower shelf impact energy measurements were also made. The results show that both manganese and nickel individually increased the cleavage fracture strength. In combination the best cleavage properties were given by alloying contents of 1.0% manganese and 1.5% nickel increasing alloying beyond this level had a detrimental effect. The mechanism for this was a combination of grain size effects, changes in the slip characteristics of the material, the size, distribution and nature of inclusions and the effects of alloying on grain boundary and matrix/inclusion cohesion. In re-heated material at test temperatures studied the plane strain fracture toughness is influenced by similar factors to those which determine cleavage fracture strength.
17
Henshel, Judy 1958. "Copper, manganese, and zinc in Puerco River sediments". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276725.
Testo completoAbstract (sommario):
A study was conducted to test for the presence of heavy metals (Cu, Mn, and Zn) in surface sediments of the Puerco River channel in the aftermath of a toxic spill in 1979 near Church Rock, New Mexico. Analysis of samples from five sites downstream from the spill showed that these substances were not present in unusually large amounts, though an increasing gradient of metal concentration with distance downstream was revealed. Statistical analysis revealed the Cu, Mn, and Zn were associated with clay and silt, soil organic matter, organic carbon, and carbonates, all of which existed as extraneous, uncontrolled variables. Adjusted metal concentrations, obtained with covariate analyses, confirmed the increasing gradient downstream. Clay and silt also increased downstream. Some toxic substances may have leached into the riverbed; possible mechanisms for this process are also discussed and further study to substantiate or disprove this hypothesis is recommended.
18
鄧煒堂 e Wai-tong Tang. "Homogeneous oxidation of organic substrates by ruthenium, iron and manganese tertiary amine complexes". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B31231706.
Testo completo
19
Tang, Wai-tong. "Homogeneous oxidation of organic substrates by ruthenium, iron and manganese tertiary amine complexes /". [Hong Kong : University of Hong Kong], 1989. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12355203.
Testo completo
20
Kogoui, Kamta Frederic Noel. "Bioaccumulation and mixture toxicity of aluminium and manganese in experimentally exposed woodlice, Porcellio scaber (Crustacea, Isopoda)". Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2677.
Testo completoAbstract (sommario):
Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2018.Soil ecosystems in urban, rural and agricultural environments receive chemical input from diverse sources of contamination, such as wastewater, industrial discharge, agricultural and urban runoff, fertilizers, vehicle leakages, landfill seepage, and animal waste overspill. Agricultural activities, transportation and industrial activities are suspected to be the highest sources of metal contamination in Cape Town. Although scientists generally have a good understanding of the toxicity of individual chemical pollutants, there is a great need to bridge the gap between our understanding of the toxic effects of exposure to individual contaminants and those effects from exposure to mixtures of chemicals. Woodlice and other soil detritivores have a particularly important ecosystem function in mineralising organic matter. Woodlice experience stress when exposed to toxic levels of metals in the diet, which can reduce feeding rates and may combine with natural stresses to reduce fitness and lower 'performance', thereby possibly resulting in these organisms being unable to completely fulfil their ecological function. The objectives of this study were: to compare how aluminium and manganese are bioaccumulated in Porcellio scaber in terms of the contribution of the hepatopancreas in metal storage compared to the rest of the body; and to determine whether mixtures of aluminium and manganese affect each other’s bioaccumulation and distribution in Porcellio scaber. Woodlice collected from a clean field site (Kirstenbosch Botanical Garden) were experimentally exposed in the laboratory to a range of environmentally relevant aluminium and manganese concentrations. The woodlice were exposed to these metals in single and mixed metal experiments. Oak leaves, collected from a clean site, were contaminated with aluminium and manganese. Therefore, the woodlice were exposed via their food source. A control experiment, where oak leaves were not contaminated, was also prepared. At week 0 and after five weeks of exposure, a sample of the woodlice (5 per exposure group) were dissected to remove the hepatopancreas. Hepatopancreas and rest of the body samples were acid digested and analysed for the metals by means of the ICP-MS. Contrary to the existing knowledge of metals accumulating in the hepatopancreas of woodlice when ingested, this study showed a higher bioaccumulation of aluminium in the rest of the body of woodlice after 5 weeks of exposure than in the hepatopancreas. This result was interpreted as a possible detoxification mechanism by woodlice through the use of the exoskeleton during the moult cycle. A similar result was found when woodlice were exposed to mixtures of aluminium and manganese. This translated to the fact that woodlice were unable to effectively deal with the toxicity caused by the mixture of aluminium and manganese. In the group of woodlice exposed to manganese alone, it was found that manganese concentrations in the rest of the body of woodlice exposed for 5 weeks were statistically higher than the manganese concentrations in the rest of the body of woodlice at the start of the exposure (week 0). However, in the hepatopancreas, there were no statistical differences between the manganese concentrations in week 0 woodlice and the manganese concentrations in week 5 woodlice. Furthermore, manganese concentrations in the rest of the body of week 5 woodlice were statistically higher than manganese concentrations in the hepatopancreas of week 5 woodlice. This was interpreted as further proof that woodlice would accumulate certain metals (aluminium and manganese in this case) in their exoskeleton so that elimination can follow during the moult cycle.
21
Rufino, Gervasio Mariano. "Bioacumulação e translocação de manganês em Sinapis alba e Brassica juncea sob doses crescentes deste metal no solo: uma alternativa de fitorremediação". Universidade de Taubaté, 2006. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=135.
Testo completoAbstract (sommario):
O objetivo do presente estudo foi avaliar a capacidade das espécies de mostarda Sinapis alba e Brassica juncea quanto à capacidade de bioacumulação e translocação de manganês, visando conhecer seu potencial de utilização para fitorremediação de solos. O experimento foi realizado em casa de vegetação na Universidade de Taubaté (UNITAU), no campus das Ciências Agrárias, utilizando Latossolo Vermelho Amarelo de classe textural franco argiloso, nas dosagens de 0, 50, 100, 200, 300, 450, 600 e 800 mg kg-1 de Mn, ajustados através de solução de MnSO4.4H2O. Após 50 dias da semeadura foi feita a colheita, lavagem, secagem e moagem da biomassa, e determinação de Mn na parte aérea e raiz. A produção de biomassa mostrou uma correlação negativa com os teores de Mn no solo, tendo a partir da dose de 200 mg kg-1 o crescimento severamente afetado tornando visíveis os sintomas de toxicidade como: manchas amarronzadas de necrose, encarquilhamento das bordas das folhas e perda da cor verde (clorose). A massa seca da parte aérea apresentou diferença significativa entre os tratamentos e na interação tratamento-espécie, sendo a Brassica juncea superior nas doses de 200 e 300 mg kg-1. A produção de massa seca de raiz também mostrou correlação negativa com os teores de Mn no solo, diferença significativa entre os tratamentos e entre as espécies sendo a Brassica juncea superior a Sinapis alba. A bioacumulação de Mn na parte aérea mostrou correlação positiva com o teor de Mn no solo e diferença estatística significativa somente entre os tratamentos. As duas espécies tiveram o mesmo nível de bioacumulação de Mn na parte aérea. Nas raízes houve diferença estatística significativa para os tratamentos nas duas espécies, e correlação positiva com o teor de Mn do solo. Apesar da Sinapis alba apresentar índice médio de translocação maior, a Brassica juncea mostrou maior conteúdo de Mn por planta, com rendimento máximo nas doses de 200 mg kg-1 e 300 mg kg-1 de Mn no solo. As duas espécies mostraram potencial para uso em fitorremediação de solos devido à alta bioacumulação de Mn (hiperacumuladoras) e translocação. A Brassica juncea mostrou-se mais promissora que a Sinapis alba, por apresentar maior tolerância a altas dosagens de Mn no solo.The aim of this work was to evaluate the manganese uptake and translocation capacity of two species of mustard, Sinapis alba and Brassica juncea, in order to know their potential for use in the phytoremediation process. The experiment was conducted in greenhouse conditions, at the Agricultural Sciences Department of Taubaté University (UNITAU), using samples of Red Yellow Latosol, argillaceous franc textural class soil. The tested soil manganese doses were 0, 50, 100, 200, 350, 450, 600 and 800 mg kg-1, using manganese sulfate in water solution. The sample soil was taken from 60 cm depth, it was bolted, made homogeneous, chemically analyzed, and nutrients adjustments were made. The harvest took place 50 days after sowing; the biomass was washed, dried until constant weight was reached, ground in type Wiley mill the manganese concentration was determined. The biomass production showed negative correlation with soil manganese concentration, having its growth rate strongly affected from 300 mg kg-1 soil manganese dosage on. Also from this soil manganese level on, toxicity symptoms were visible, such as brown speckles that started on the tips of the older leaves and spread down the leaf until the entire blade was covered; chlorosis and necrosis that effectively reduced the photosynthetic capacity of the plants. The tissue dried biomass showed statistical difference among dosages and in dosage-specie interaction, with Brassica juncea showing greater difference than Sinapis alba in 200 and 300 mg kg-1 soil Mn doses. The tissue manganese bioaccumulation showed positive correlation with soil manganese level and significant difference among treatments. Both species had the same tissue bioaccumulation level. The manganese root concentration also had positive correlation with soil manganese, and statistical difference for treatments was present in both species. Although Sinapis alba translocation index was better, Brassica juncea had greater manganese content level, with best results in 200 and 300 mg kg-1 manganese soil dose. Both species showed good potential for use in soil phytoremediation processes, due to high manganese bioaccumulation and translocation level.
22
Cussen, Edmund John. "The electronic properties of mixed metal oxides". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301436.
Testo completo
23
Dubarle, Offner Julien. "Novel heterobimetallic manganese-chromium and rhenium-chromium complexes : coordination, cyclometallation, benzannulation and haptotropic metal migration". Paris 6, 2009. http://www.theses.fr/2009PA066040.
Testo completoAbstract (sommario):
Une propriété caractéristique des complexes formés par des métaux de transition et des ligands polycycliques aromatiques est leur capacité à se soumettre à des réarrangements haptotropiques ; le fragment métallique est considéré comme le groupe fonctionnel déplaçable qui migre entre deux cycles non-équivalents du ligand hydrocarboné. Nous avons décidé de coordiner d’autres métaux de transition aux complexes (polyarène)Cr(CO)3 afin d’étudier leurs différentes influences sur la migration du tricarbonylchrome. Dans ce contexte, les premiers complexes hétérobimétalliques syn et anti Cr(CO)3-Mn(CO)3 et Cr(CO)3-Re(CO)3 ont été synthétisés. De plus, la synthèse de nouveaux complexes du tricarbonylchrome avec un polyarène N-hétérocyclique a été étudiée, ainsi que leur équivalents cyclomanganatés. Dans toutes ces synthèses, la benzannulation [3+2+1] de carbène de Fischer portant une unité métallique additionnelle a été employée afin d’introduire l’atome de chrome sur le ligand. Les migrations haptotropiques thermiquement induites du chrome le long des plateformes aromatiques ont été exécutées sur tous les complexes et ont conduit dans la plupart des cas aux haptotropomères thermodynamiques souhaités. Les déplacements intramoléculaires du fragment chromique ont été confirmés avec des études cinétiques par RMN qui ont montré une cinétique de premier ordre. De plus, toutes les structures hétérobimétalliques ont été déterminées par des analyses cristallographiques.
24
Eriksson, Therese. "The Structural Basis for Magnetic Order in New Manganese Compounds". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5746.
Testo completo
25
Qwesha, Sibusiso. "Electrodeposition of multi-valent metal oxides at 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquid - carbon paste electrode". University of the Western Cape, 2012. http://hdl.handle.net/11394/4618.
Testo completoAbstract (sommario):
>Magister Scientiae - MScA study on carbon paste electrode (CPE) materials containing 1-methyl-3-octylimidazolium bis (trifluoromethylsulfonyl) imide [MOIM[Tƒ2N] – a hydrophobic room temperature ionic liquid (IL) - is reported. CPEs with (a) the IL as the only binder (ILCPE) and (b) 1:1 (v/v) IL: paraffin mixture as the binder (ILPCPE) were prepared, characterized, and applied to the electrodeposition of films of multivalent transition metal oxides (MV-TMO) from five precursor ions (Fe2+, Mn2+, Cu2+, Co2+, Ce4+) in aq. KCl. Cyclic voltammetry (CV) showed a potential window of +1.5 V to -1.8 V regardless of the electrode type, including the traditional paraffin CP electrode (PCPE). However, the IL increased the background current by 100-folds relative to paraffin. The electrochemical impedance spectroscopy (EIS) of ILPCPE in aq. KCl (0.1M) revealed two phase angle maxima in contrast with the single maxima for PCPE and ILCP. The study also included the CV and EIS investigation of the electrode kinetics of the Fe(CN)6 3-/4 redox system at these electrodes. The electrodeposition of Fe2+, Co2+, and Mn2+ possibly in the form of the MV-TMOs FexOy, CoxOy, and MnxOy, respectively, onto the electrodes was confirmed by the observation of new and stable cathodic and anodic peaks in a fresh precursor ion –free medium. CVs of H2O2 as a redox probe supported the same conclusions. Both ATR-FTIR spectra and SEM image of surface samples confirmed the formation of electrodeposited films. This study demonstrated that the use of this hydrophobic IL alone or in combination with paraffin as a binder gives viable alternative CPE materials with better performance for the electrodeposition of MV-TMOs films than the paraffin CPE. Thus, in combination with the easy preparation methods and physical “morpheability” in to any shape, these CPEs are potentially more useful in electrochemical technologies based on high surface-area MV-TMO films in general, and MnxOy films in particular.
26
Ruan, Zhixiong. "C−H Alkylations and Alkynylations Using Ruthenium, Nickel and Manganese Complexes". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://hdl.handle.net/11858/00-1735-0000-0023-3F33-6.
Testo completo
27
Metz, Gretchen Lee. "Reduction chemistry of dibenzothiophene manganese tricarbonyl cation and reactions of phospholes with group six metal carbonyls /". Connect to online version, 1997. http://hdl.handle.net/1989/3740.
Testo completo
28
Seidel, Renate Magdalene. "Molekulare Mangan-,Eisen- und Cobalt-Komplexe mit neuartigen Metall-Chalcogen-Gerüsten - Molecular manganese-, iron- and cobalt-complexes with novell metal-chalcogenides frameworks". Gerhard-Mercator-Universitaet Duisburg, 2001. http://www.ub.uni-duisburg.de/ETD-db/theses/available/duett-10042001-202230/.
Testo completoAbstract (sommario):
The possibility of synthesis of (poly-)chalcogenide and chalcogenolate ions to manganese, iron and cobalt was expanded with the introduction of the donor ligand carbon monoxide. The metal atoms get than greater coordination numbers. So it was possible to synthesise new metal frameworks, p. e. Co11E7 in the complexes [Ph4P]2[Co11Se7(CO)10] and [Ph4P]2[Co11Te7(CO)10], in which the cobalt atoms built a inner centred pentagonal prism. In the examined reaction systems Mn2(CO)10/Na2Sex/Kat, Fe(CO)5/Na2Ex/Kat and Co2(CO)8/Na2Ex/Kat (E = Se or Te; x = 1 or 2; Kat = Ph4PCl or PPNCl) succeeded the synthesis of [Co6Se8(CO)6]-/2-anions as first anionic clusters of the M6E8L6 class. The difference between the new [Co6Se8(CO)4]- anion and the M6E8L6-complex class is the extraordinary compressed Co6-oktaeder and considerable shorter Co-Co-distances. In addition to the higher mentioned compounds it was possible to synthesise and characterize unambiguous with the aid of single crystal x-ray crystallography the following complexes: [Ph4P]2[Fe3Te(CO)9]; [Ph4P][Fe3EH(CO)9] für E=Se,Te; [Ph4P]2 [Fe4Te2(CO)14]; [Ph4P]2 [Fe6Se6(CO)12]; [Ph4P]2 [Mn3Se2(CO)9]. Worth mentioning is also the unusual square pyramidal coordination of the manganese atom in the [Ph4P][Mn(CO)5] crystal. Until now were only penta carbonyl complexes known with a trigonal bipyramidal coordination.
29
Vogel, Anastasia. "The Siamese-Twin Porphyrin and its Metal Complexes: Platforms for Multi-Electron Redox Chemistry". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2016. http://hdl.handle.net/11858/00-1735-0000-002B-7D43-3.
Testo completo
30
Ferrandon, Magali. "Mixed metal oxide - noble metal catalysts for total oxidation of volatile organic compounds and carbon monoxide". Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3156.
Testo completo
31
Zhang, Huichun. "Metal oxide-facilitated oxidation of antibacterial agents". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-07072004-152317/unrestricted/zhang%5Fhuichun%5F200407%5Fphd.pdf.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2005. Directed by Ching-Hua Huang.Wine, Paul, Committee Member ; Pavlostathis, Spyros, Committee Member ; Mulholland, James, Committee Member ; Yiacoumi, Sotira, Committee Member ; Huang, Ching-Hua, Committee Chair. Includes bibliographical references.
32
何振華 e Chun-wah Ho. "Study on osmium and manganese complexes of chiral binaphthylic tetradentate ligands and their application to asymmetric epoxidationof alkenes". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31233570.
Testo completo
33
Keech, Angus Miles. "Role of cobalt(II) and manganese(II) as optical and magnetic probes of metal binding sites in proteins". Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389267.
Testo completo
34
Zhu, Cuiju. "Sustainable Synthesis by 3d Transition Metal Electro-Catalyzed C─H Activation". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0005-12F3-4.
Testo completo
35
Paudel, Moti Raj. "A comprehensive experimental study of the quaternary Heusler alloy cobalt-manganese-tin-antimony : a potential half-metal /". Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1597633341&sid=5&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Testo completo
36
Madouri, Ali. "Heterodiffusion du manganese dans la wuestite : fe1-y o::(-)". Paris 7, 1987. http://www.theses.fr/1987PA077285.
Testo completoAbstract (sommario):
Les coefficients de diffusion de mn dans feo sont mesures en fonction de la temperature (700**(o)c-1100**(o)c) pour quatre valeurs du rapport r=pco::(2)(pco (r=0,7; 1,0; 1,8; 2,5). Les coefficients de diffusion du manganese sont systematiquement plus eleves que les coefficients d'autodiffusion du fer pris dans la litterature (chen et peterson, 1973) a cause de l'energie d'activation de d::(mn) plus faible que celle de d::(fe). Les resultats de diffusion d'interpretent en termes d'interactions attractives entre les lacunes et les atomes de manganese
37
Chang, Hyun-Shik. "Determination of oxidation mechanism of ethylenediaminetetraacetate (EDTA)-metal complexes by alkaline permanganate and structures of in situ formed manganese oxides containing heavy metals /". Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/10106.
Testo completo
38
Ho, Chun-wah. "Study on osmium and manganese complexes of chiral binaphthylic tetradentate ligands and their application to asymmetric epoxidation of alkenes /". [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13787020.
Testo completo
39
Sauermann, Nicolas. "C-H Activation for Sustainable Synthesis: Base Metal- and Electro-Catalysis". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E46C-2.
Testo completo
40
Mitchell, Michael S. "Oxidation of biological molecules with bicarbonate-activated hydrogen peroxide and the decomposition of hydrogen peroxide catalyzed by manganese(II) and bicarbonate". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004948.
Testo completo
41
Zheng, Jianxia. "Earth-abundant metal complexes for catalyzed hydroelementation". Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S148/document.
Testo completoAbstract (sommario):
Ce travail de recherche est consacré au développement de catalyseurs à base de métaux de transition abondants de la première rangée du tableau périodique, tels que Mn, Fe, et Ni, pour les réactions d'hydro-élémentation. Tout d'abord, l'hydrosilylation de cétones et d'aldéhydes a été accomplie en utilisant un système catalytique simple Ni(OAc)₂ 4H2O/PCy₃ avec le PMHS, silane peu coûteux et stable en tant que source d'hydrure. L'amination réductrice d'aldéhydes avec des amines a également été réalisée avec le même système catalytique et le TMDS, comme silane. Deuxièmement, l’efficacité des complexes de manganèse demi-sandwich CpMn(CO)₂(IMes) a été prouvée pour la réduction des aldéhydes et des cétones en présence de Ph₂SiH₂ (1,5 équiv.) sous irradiation UV. La transformation difficile d'acides carboxyliques en aldéhydes a été effectuée à l'aide de Mn₂(CO)₁₀ et de Et3SiH. Troisièmement, la méthylation des amines secondaires avec le carbonate de diméthyle en tant que source C1 a été démontrée dans des conditions catalytique douces avec [CpFe(CO)₂(IMes)]I. Ensuite, l'hydroboration d'alcènes et d'alcynes fonctionnalisés a été réalisée en présence d’un complexe de fer (0), Fe(CO)₄(IMes) sous irradiation UV. Enfin, la réaction d'hydroboration a été étendue avec succès à la réduction de CO₂ en methoxyboranes avec Fe(CO)₃[P(OPh)₃]₂ en tant que catalyseur et les diverses sources de borane, tels que HBpin, HBcat ou 9-BBNThis research work deals with the use of the catalysts based on the earth-abundant transition metals of the first row of the periodic table, such as Mn, Fe, and Ni, for hydroelementation reactions. First of all, the hydrosilylation of aldehydes and ketones was accomplished using a simple Ni(OAc)₂ 4H₂O/PCy₃ catalytic system with the inexpensive and stable silane PMHS as the hydride source. The reductive amination of aldehydes with amines was also achieved with the same catalytic system and TMDS, as the silane. Second, the efficiency of manganese half-sandwich complex CpMn(CO)₂(IMes) was exemplified for the reduction of aldehydes and ketones in the presence of Ph ₂ SiH ₂ (1.5 equiv.) under UV irradiation at room temperature. Still with manganese, the challenging transformation of carboxylic acids to aldehydes was performed using commercial Mn₂ (CO)₁₀ and Et₃SiH. Third, the methylation of the secondary amines with dimethyl carbonate as an alternative and safe C1 source was demonstrated under mild conditions with [CpFe(CO)₂(IMes)]I as the catalyst. Then, the hydroboration of functionalized alkenes and alkynes was catalyzed by an iron(0) carbonyl complex Fe(CO)₄(IMes) under UV irradiation. Finally, the hydroboration reaction was successfully extended to the reduction of CO₂ to methoxyboranes with Fe(CO)₃[P(OPh)₃]₂ as the catalyst and the borane sources, such as HBpin, HBcat or 9-BBN
42
Chen, Wan-Ru. "Interactions of tetracycline antibiotics with dissolved metal ions and metal oxides". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24698.
Testo completoAbstract (sommario):
Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Chair: Huang, Ching-Hua; Committee Member: Kim, Jaehong; Committee Member: Pavlostathis, Spyros; Committee Member: Stack, Andrew; Committee Member: Yiacoumi, Sotira
43
Wilkin, Owen Michael. "A matrix isolation study of monomeric 3d transition metal dihalides and their interaction with inert and reactive ligand matrices". Thesis, University of Portsmouth, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310393.
Testo completo
44
Brion, Jean-Marc. "Contribution à l'étude des mécanismes de formation de couches de transfert non métalliques sur un outil en coupe continue d'aciers de décolletage a inclusions contrôlées". Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL043N.
Testo completoAbstract (sommario):
On présente l'étude des mécanismes de formation des couches de transfert sélectif (CTS) de sulfures de manganèse sur un outil de coupe a partir des seules inclusions contenues de façon contrôlée dans l'acier usiné. On montre que la stabilité de la CTS sur l'outil correspond à un équilibre dynamique entre sa vitesse d'alimentation et sa vitesse d'érosion avec l'adhérence inclusion/outil comme mécanisme clé gouvernant cette stabilité. Cette adhérence est liée à l'affinité chimique entre l'élément métallique actif présent à la surface de l'outil (Zr, ti) et le soufre des inclusions de l'acier exprimée en termes d'enthalpie de formation du sulfure correspondant. Par spectroscopie des électrons Auger en mode balayage, nous avons réussi à comprendre le mécanisme le plus probable d'accrochage des sulfures de manganèse sur des outils mixtes composes de carbures WC et tic. A l'endroit des carbures simples de type wc, on assiste a une usure diffusionnelle classique qui se traduit par leur dissociation et évacuation continuelles. En revanche, l'élément de transition (ti) dans les carbures actifs également dissociés forme, avec les inclusions de l'acier usine, une fine couche d'oxysulfure stable, et certainement adhérente, qui interrompt cette dissociation et constitue une base d'accrochage pour d'autres sulfures. Dans la même logique, on constate que la continuité chimique du compose actif à la surface de l'outil (outils revêtus) favorise encore la stabilité des CTS. Bien que d'importance cruciale, la maitrise compositionnelle de la surface de l'outil ne peut avoir qu'un rôle de révélateur du flux d'alimentation en inclusions provenant du copeau. On montre le rôle capital qui revient au contrôle inclusionnaire en matière de composition des inclusions principalement mais aussi en termes de morphologie et de déformabilité relative inclusion/matrice
45
Thomson, Bruce Winchester. "Heavy metal uptake on manganese oxide : coated filter sand obtained from the forehill water treatment plant, Peterhead, Aberdeenshire". Thesis, Robert Gordon University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289088.
Testo completo
46
Krinks, John K. "Microbial Assessment of a Bioremediation System Treating Acid Mine Drainage". Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1181069690.
Testo completo
47
Mabad, Bouchra. "Modelisation du site d'oxydation de l'eau en photosynthese : complexes du manganese avec des bases de schiff polydentees". Toulouse 3, 1987. http://www.theses.fr/1987TOU30103.
Testo completo
48
Butterfield, Martin Thomas. "Surface structure of ultrathin metal films deposited on copper single crystals". Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/33132.
Testo completoAbstract (sommario):
Ultrathin films of Cobalt, Iron and Manganese have been thennally evaporated onto an fcc Copper (111) single crystal substrate and investigated using a variety of surface structural teclmiques. The small lattice mismatch between these metals and the Cu (111) substrate make them an ideal candidate for the study of the phenomena of pseudomorphic film growth. This is important for the understanding of the close relationship between film structure and magnetic properties. Growing films with the structure of their substrate rather than their bulk phase may provide an opportunity to grow materials with novel physical and magnetic properties, and hence new technological applications. Both Cobalt and Iron have been found to initially maintain a registry with the fee Cu (111) surface in a manner consistent with pseudomorphic growth. This growth is complicated by island rather than layer-by-layer growth in the initials stages of the film. In both cases a change in the structure of the film seems to occur at a point where the coalescence of islands in the film may be expected to occur. When the film does change structure they do not form a perfect over-layer with the structure of their bulk counterpart. The films do contain a number of features representative of the bulk phase but also contain considerable disorder and possibly remnants of fcc (111) structure. The order present in these films can be greatly improved by annealing. Manganese appears to grow with an fee Mn (111) lattice spacing and there is no sign of a change in structure in films of up to 4.61 ML thick. The gradual deposition and annealing of a film to 300°C, with a total deposition time the same as that for a 1 ML thick film, causes a surface reconstruction to occur that is apparent in a R30° (√3×√3) LEED pattern. This is attributed to the formation of a surface alloy, which is also supported by the local expansion of the Cu lattice in the (111) direction.
49
Chavant, Pierre Yves. "Reaction de type barbier ou reformatsky effectuees a l'aide de manganese". Paris 6, 1988. http://www.theses.fr/1988PA066138.
Testo completoAbstract (sommario):
Etude de la reactivite du manganese metallique vis-a-vis d'halogenures allyliques et d'halogeno-2 esters. Une etude de l'influence du solvant et de la presence de divers sels metalliques, a debouche sur la mise au point d'une nouvelle voie d'acces a des alcools homoallyliques
50
Taujale, Saru. "INTERACTIONS BETWEEN METAL OXIDES AND/OR NATURAL ORGANIC MATTER AND THEIR INFLUENCE ON THE OXIDATIVE REACTIVITY OF MANGANESE DIOXIDE". Diss., Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/347169.
Testo completoAbstract (sommario):
Civil EngineeringPh.D.
Mn oxides have high redox potentials and are known to be very reactive, rendering many contaminants susceptible to degradation via oxidation. Although Mn oxides typically occur as mixtures with other metal oxides (e.g., Fe, Al, and Si oxides) and natural organic matter (NOM) in soils and aquatic environments, most studies to date have studied the reactivity of Mn oxides as a single oxide system. This study, for the first time, examined the effect of representative metal oxides (Al2O3, SiO2, TiO2, and Fe oxides) and NOM or NOM-model compounds (Aldrich humic acid (AHA), Leonardite humic acid (LHA), pyromellitic acid (PA) and alginate) on the oxidative reactivity of MnO2, as quantified by the oxidation kinetics of triclosan (a widely used phenolic antibacterial agent) as a probe compound. The study also examined the effect of soluble metal ions released from the oxide surfaces on MnO2 reactivity. In binary oxide mixtures, Al2O3 decreased the reactivity of MnO2 as a result of both heteroaggregation and complexation of soluble Al ions with MnO2. At pH 5, the surface charge of MnO2 is negative while that of Al2O3 is positive resulting in intensive heteroaggregation between the two oxides. Up to 3.15 mM of soluble Al ions were detected in the supernatant of 10 g/L of Al2O3 at pH 5.0 whereas the soluble Al concentration was 0.76 mM in the mixed Al2O3 + MnO2 system at the same pH. The lower amount of soluble Al in the latter system is the result of Al ion adsorption by MnO2. The experiments with the addition of 0.001 to 0.1 mM Al3+ to MnO2 suspension indicated the triclosan oxidation rate constant decreased from 0.24 to 0.03 h-1 due to surface complexation. Fe oxides which are also negatively charged at pH 5 inhibited the reactivity of MnO2 through heteroaggregation. The concentration of soluble Fe(III) ions ( 4 mg-TOC/L or [alginate/PA] > 10 mg/L, a lower extent of heteroaggregation was also observed due to the negatively charged surfaces for all oxides. Similar effects on aggregation and MnO2 reactivity as discussed above were observed for ternary MnO2‒Al2O3‒NOM systems. HAs, particularly at high concentrations (2.0 to 12.5 mg-C/L), alleviated the effect of soluble Al ions on MnO2 reactivity as a result of the formation of soluble Al-HA complexes. Alginate and PA, however, did not form soluble complexes with Al ions so they did not affect the effect of Al ions on MnO2 reactivity. Despite the above observations, the amount of Al ions dissolved in MnO2+Al2O3+NOM mixtures was too low, as a result of NOMs adsorption on the surface to passivate oxide dissolution, to have a major impact on MnO2 reactivity. In conclusion, this study provided, for the first time, a systematical understanding of the redox activity of MnO2 in complex model systems. With this new knowledge, the gap between single oxide systems and complex environmental systems is much narrower so that it is possible to have a more accurate prediction of the fate of contaminants in the environment.
Temple University--Theses