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Tesi sul tema "Sulfide"
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1
Huang, Zhen. "Synthesis of sulfide and sulfone 2'-deoxyribonucleotide analogues /". [S.l.] : [s.n.], 1993. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10429.
Testo completo
2
Siu, Tung. "Kinetic and mechanistic study of aqueous sulfide-sulfite-thiosulfate system". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0007/MQ45585.pdf.
Testo completo
3
Li, Wen. "Synthesis and solubility of arsenic tri-sulfide and sodium arsenic oxy-sulfide complexes in alkaline sulfide solutions". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44546.
Testo completoAbstract (sommario):
Alkaline sulfide leaching (ASL) at approximately 100 ºC has been used to selectively extract arsenic and antimony from enargite and tetrahedrite concentrates. Sodium thio-arsenate has been postulated to crystallize from alkaline sulfide leaching solutions upon cooling. However, literature data on the solubility of sodium thio-arsenate as well as proof of its crystallization from ASL solutions is scant. In this thesis, the solubility of leach-produced and synthetic sodium thio-arsenate is studied.
To determine arsenic solubility in ASL solutions, sodium thio-arsenate and sodium arsenic oxide sulfide complexes are synthesized by various means and characterized by EDX, QXRD, and ICP.
The synthesis of amorphous As₂S₃, sodium arsenic oxy-sulfide complexes, and sodium thio-arsenate is first presented. For amorphous As₂S₃ synthesis, the effect of concentration of sodium sulfide (0.1 M) and hydrochloric acid (1 M), temperature (40 ~ 60 ºC), and aging time (48 hours) was optimized. The solubility of synthetic sodium arsenic oxy-sulfide complexes and sodium thio-arsenate in ASL solutions increases significantly as temperature is increased to 95 ºC. More importantly, the solubility of sodium thio-arsenate at certain temperatures is significantly affected by the concentration of sodium hydroxide and sulfide in solution. Due to the common ion effect, if NaOH and HS- concentrations are very high, the solubility of sodium thio-arsenate decreases.
Enargite leaching tests were done to characterize the precipitate that occurred upon cooling and to verify the arsenic saturation point, which should be between 38.5 ~ 58 g/L (0.51 M ~ 0.78 M) As depending on the NaOH and HS- concentration. Comparison with solubility experiments of pure sodium thio-arsenate shows that arsenic solubility in ASL solutions is supersaturated. However, direct comparison of saturation in ASL solutions and the solubility as obtained by the synthetic solutions/crystallites prepared here is not possible given the complex nature of the ASL crystallites that appear not to contain the often discussed “sodium thio-arsenate”.
4
Babcock, Kevin Brian. "Alkali carbonate-sulfide electrolytes for medium temperature hydrogen sulfide removal". Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/12959.
Testo completo
5
Huang, Shanshan. "Nanoparticulate nickel sulfide". Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54754/.
Testo completoAbstract (sommario):
Nickel sulfide possesses a variety of typical structures and stoichiometries that distinguish itself from iron sulfide and exhibits unique roles in the prebiotic reactions which are proposed to be involved in the origin of life. Nickel sulfide precipitate is hydrated and nanocrystalline, modelled as a 4 nm sphere with a 1 nm crystalline and anhydrous NiS (millerite) core, surrounded by a hydrated and defective mantle phase. It is a metastable but fairly robust structural configuration. It may be formulated as NiSxFbOx approximates to 1.5 and decreases on heating. The fresh nanoparticulate nickel sulfide precipitates undergo structural transformation from the initial millerite-like NiS to the more crystalline polydymite-like Ni3S4. This reaction is accompanied by the formation of a less crystalline Ni3S2 (heazlewoodite) phase. The reaction, happening in ambient conditions, occurs more readily for the solids precipitated from acidic environments (i.e., pH 3) and may be facilitated by the hydrogen and water bonding contained in this material. The performance of nickel sulfide and iron sulfide precipitates is investigated in the formaldehyde world under ambient and sulfidic environments which mimic the ambient ancient Earth environments to some extent. The catalytic capacity of the metal sulfides is not obvious in these experiments. An interesting finding is that, trithiane, the cyclic (SCH2)3, also suppresses the pyrite formation and thus promotes the greigite formation in the reaction between FeS and H2S. This provides another cause for the greigite formation in the Earth sedimentary systems and adds information to the origin-of-life theory in the iron sulfur world. Voltammetry experiments reveal that the nickel-cysteine complex lowers the overpotential for molecular H2 evolution in sea water to -1.53 V under ambient conditions. This catalytic property of the abiotic nickel-cysteine complex apparently mimics the Ni-S core in some hydrogenase enzymes functioning in physiological conditions. This bridges the abiotic and biotic worlds and supports the idea that life originated in the prebiotic ancient ocean.
6
Rijal, Upendra. "Suppressed Carrier Scattering in Cadmium Sulfide-Encapsulated Lead Sulfide Nanocrystal Films". Bowling Green State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1402409476.
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7
Rajan, C. R. "Studies on polyphenylene sulfide". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1986. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3262.
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8
Park, Yeseul. "Metal sulfide biomineralization by magnetotactic bacteria". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0262.
Testo completoAbstract (sommario):
La biominéralisation de sulfures métalliques est observée tant dans des cultures microbiennes que dans la nature. Cependant, seulement quelques cas ont été définis comme étant des processus biologiquement contrôlés comme cela est le cas pour la greigite produite par les bactéries magnétotactiques. Pendant ma thèse, j'ai découvert un nouveau type de biominéralisation intracellulaire de sulfure métallique en étudiant l'impact du cuivre sur la biominéralisation de la greigite par la bactérie Desulfamplus magnetovallimortis BW-1.Le biominéral que j'ai identifié a une structure et une organisation cristalline originales. Les particules sont de morphologie sphérique ou ellipsoïdale et composées de sous-grains de 1 à 2 nm de sulfure de cuivre hexagonal qui reste dans un état métastable. Les particules sont situées dans le périplasme, et sont entourées d'une substance organique. Sur la base de ces observations, j'ai conclu que le biominéral est produit et conservé grâce à un contrôle biologique. En conséquence, j'ai mené des études de protéomique pour trouver des protéines associées au processus qui ont mis à jour deux protéines périplasmiques, une protéine résistante aux métaux lourds et une protéase de type DegP, qui fonctionnent probablement ensemble pour réagir au stress causé par le cuivre.Une telle biominéralisation intracellulaire est spécifique à BW-1et n'est initiée que par les ions cuivre, mais pas par d'autres ions métalliques comme le nickel, le zinc ou le cobalt. Mes recherches de doctorat révèlent donc des caractéristiques inconnues de la biominéralisation des sulfures métalliques, en particulier au sein des bactéries magnétotactiquesBiomineralization of metal sulfides has been broadly observed in microbial cultures and in nature. However, only a few cases have been reported as biologically-controlled processes, such as greigite produced by magnetotactic bacteria. I discovered a new type of intracellular metal sulfide biomineralization, while studying the impact of copper on greigite biomineralization by the magnetotactic bacterium Desulfamplus magnetovallimortis strain BW-1.The newly discovered metal sulfide biominerals are nanoscopic particles and have an interesting crystal structure and organization. These spherical or ellipsoidal particles are composed of 1-2 nm-sized sub-grains of hexagonal copper sulfide that remains in a metastable state. The particles are located in the periplasmic space, surrounded by an organic substance. Based on these observations, it was concluded that the biomineral produced and conserved is a result of biological control. Proteomics studies with cellular and particulate samples identified several proteins associated with the process. The initial result showed that two periplasmic proteins, a heavy metal resistant protein, and a DegP-like protease, are likely working together to react to the envelope stress caused by copper. Such intracellular biomineralization is organism-specific and only initiated by the increase of copper ions, but not by other metal ions like nickel, zinc, or cobalt. Overall, my work reveals unknown features of metal sulfide biomineralization, specifically within magnetotactic bacteria
9
D'Aoust, Patrick Marcel. "Stormwater Retention Ponds: Hydrogen Sulfide Production, Water Quality and Sulfate-Reducing Bacterial Kinetics". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35562.
Testo completoAbstract (sommario):
Stormwater retention basins are an integral component of municipal stormwater management strategies in North America. The province of Ontario’s Ministry of the Environment and Climate Change obligates land developers to implement stormwater management in their land use and development plans to mitigate the effects of urbanization (Bradford and Gharabaghi, 2004). When stormwater retention ponds are improperly designed or maintained, these basins can fail at improving effluent water quality and may exasperate water quality issues.
Intense H2S production events in stormwater infrastructure is a serious problem which is seldom encountered and documented in stormwater retention ponds. This study monitored two stormwater retention ponds situated in the Riverside South community, Ottawa, Ontario, Canada for a period of 15 consecutive months to thoroughly characterize intense hydrogen sulfide (H2S) production in a stormwater retention pond under ice covered conditions during winter operation and during periods of drought under non-ice covered conditions during the summer.
Field experiments showed a strong relationship (p < 0.006, R > 0.58, n = 20+) between hypoxic conditions (dissolved oxygen (DO) concentration < 2 mg/L) and the intense production of H2S gas. Ice-capping of the stormwater ponds during winter severely hindered reaeration of the pond and led to significant production of total sulfides in the Riverside South Pond #2 (RSP2), which subsequently resulted in the accumulation of total sulfides in the water column (20.7 mg/L) during winter in this pond. There was a perceived lag phase between the drop in DO and the increase in total sulfides near the surface, which was potentially indicative of slow movement of total sulfides from the benthic sediment into the water column. These high-sulfide conditions persisted in RSP2 from early January 2015 until the spring thaw, in mid-April, 2015. Riverside South Pond #1 (RSP1), the reference pond studied in this work, showed significantly less production of total sulfides across a significantly shorter period of time. Analysis of the microbial communities showed that there was little change in the dominant bacterial populations present in the benthic sediment of the pond demonstrating significant total sulfide production (RSP2) and the pond that did not demonstrate significant total sulfide production (RSP1). Additionally, it was found that locations with the most accumulated sediment had the highest propensity for the production of H2S gas. Furthermore, there was no perceivable community shift in the two ponds throughout the seasons, indicating that the sulfate-reducing bacteria (SRB) in stormwater benthic sediment are ubiquitous, exist in an acclimatized microbial population and are robust. Study of the microbial abundances revealed that SRB represented approximately 5.01 ± 0.79 % of the microbes present in the benthic sediment of RSP2. Likewise, in the stormwater pond which did not experience intense H2S gas production, RSP1, 6.22 ± 2.11 % of microbes were of the SRB type, demonstrating that H2S gas production does not correspond to higher concentrations of SRB or the proliferation of dominant species, but rather is a symptom of increased bacterial activity due to favourable environmental conditions.
In addition, this work also covers the kinetics of sediment oxygen demand (SOD), ammonification and sulfate-reduction, and attempts to understand the processes leading to H2S gas production events.
In doing so, it was observed that kinetics obtained full-scale field studies were greater than in laboratory kinetic experiments. Laboratory experiments at 4°C identified total SOD, ammonification and sulfate-reduction kinetics to be 0.023 g/m2/day, 0.027 g N/m2/day and 0.004 g S/m2/day, respectively. Meanwhile, kinetics calculated from the field study of stormwater retention ponds for total SOD, ammonification and sulfate-reduction were of 0.491 g/m2/day, 0.120 g N/m2/day and 0.147 g S/m2/day, respectively. It is expected that this difference is due to the depth of active sediment influencing the total rates of production/consumption, making area-normalized daily rates of production/consumption (g/m2/day) unsuitable for the comparison of field and laboratory studies, without some scaling factor. This study also measured supplementary kinetic parameters such as the Arrhenius coefficients and the half-saturation coefficient, to add to existing knowledge of sulfate-reduction.
10
Meng, Bin. "Synthesis and binding of oligonucleotides containing 2'-modified sulfide- or sulfone-linked dimers". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28493.
Testo completoAbstract (sommario):
Three activated modified dimers 9, 21 and 35, which contain a dialkyl sulfide backbone, have been synthesized.These dimers, as well as dimer A, have been incorporated into DNA strands by solid-phase techniques. The number of these dimers being incorporated varied from 1-3.$ sp*$
Thermal studies have shown that the oligomers containing modified dimers indeed bind to their complementary DNA or RNA, except for two oliglomers in which dimer 9 or 21 was incorporated three times. They only bind relatively poorly to complementary RNA, but not at all to DNA. The incorporation of 35 into DNA oligomers showed good binding to its complementary RNA, but not DNA.
All sulfide-containing oligomers have been oxidized to sulfone-containing oligomers using oxone. In thermal studies, hybrids of the sulfone-containing oligomers with their complementary DNA and RNA showed much poorer binding properties than the corresponding sulfide-containing oligomers.
The synthesis of nucleoside 28, the upper half of dimer 21, as well as an improved procedure for the preparation of 2$ sp prime$-O-methyluridine, are described. ftn$ sp*$Please refer to the dissertation for diagrams.
11
Joon, Won Lee. "The fundamental dissolution kinetics of silver sulfide and mercury sulfide in atmospheric cyanide solutions". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44575.
Testo completoAbstract (sommario):
The dissolution kinetics of pure silver sulfide (acanthite) and mercury sulfide (metacinnabar) were investigated using rotating disc and stirred reactor methods and the results were explained using the Levich and shrinking-core Parabolic Leach equations, respectively. It was observed that silver sulfide dissolution was limited by cyanide mass-transport and mercury sulfide by parabolic leaching. Silver sulfide leaching was practically unaffected by pH and dissolved oxygen concentrations while mercury sulfide leaching was sensitive to both parameters. Dissolution rates of both species increased linearly with cyanide concentration and activation energies were calculated using the Arrhenius rate equation as 5.15kJ/mol and 5.81kJ/mol, respectively, which indicates mass-transport control. It was also considered that silver sulfide dissolution is supressed by sulfide-saturation in the solution, while mercury dissolution is inhibited by the growth of sulfur-rich product layers on the particles. Kinetic results were compared to extraction experiments conducted on a spent Heap Leach Residue sample from the Yanacocha Mine in Peru which contained acanthite and cinnabar as its primary silver and mercury species. Extraction kinetics of silver from the Leach Residue was analogous to pure silver sulfide’s experimental results, except that extraction rates decreased with pH. Mercury extraction from the residue was insensitive to both cyanide and pH, but was responsive to oxygen concentration. The discrepancies between pure sample investigations and the Leach Residue suggest that unforeseen interactions with other minerals may be affecting the extraction rates of silver and mercury from the Yanacocha Mine.
12
Hickey, Carolyn Frances. "Optical, chemical, and structural properties of thin films of samarium-sulfide and zinc-sulfide". Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184263.
Testo completoAbstract (sommario):
The development of materials for optical thin film application is essential to progress in fields such as optical data storage and signal processing. Samarium sulfide (SmS) thin films were prepared by reactive evaporation of samarium in hydrogen sulfide (H₂S). These displayed optical switching properties despite the presence of large amounts of carbon and oxygen. They are therefore potentially useful for data storage. The semiconductor to metal phase transition was characterized by x-ray diffraction and spectrophotometry. The observed optical response was modelled by a Bruggeman effective medium calculation. Success with this analysis suggests it as a means for predicting performance in subsequent applications. Zinc sulfide (ZnS) thin films were prepared by molecular beam epitaxy (MBE). Implimentation of an H₂S treated silicon surface provided good chemical bond match in addition to a good lattice match. Atomic layer epitaxy was unsuccessfully explored as a means to grow ZnS from zinc and H₂S reactants, therefore other reactants are proposed. Both the MBE and ALE work is directed at the long term goals of producing p-type ZnS, which is suitable for semiconductor lasing at short wavelengths, and high quality SmS thin films.
13
Wu, Xiawa. "Properties of thin film cadmium sulfide used in cadmium telluride/cadmium sulfide solar cell". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 79 p, 2009. http://proquest.umi.com/pqdweb?did=1654493821&sid=1&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Testo completo
14
Blackstone, Eric A. "Hydrogen sulfide induced suspended animation /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/5075.
Testo completo
15
Young, Aidan Gerard, e n/a. "Chemistry at cadmium sulfide surfaces". University of Otago. Department of Chemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080806.164202.
Testo completoAbstract (sommario):
Probing the surface chemistry of thiol ligand binding to cadmium chalcogenide nanoparticles is important to clarify factors involved in quantum dot stability and surface functionalisation. This research is a spectroscopic investigation aimed at gaining a better understanding of the interaction/bonding of various ligands to CdS, with respect to the use of CdS in biological imaging. The findings of this research are important to the more general field of cadmium chalcogenide materials as biological imaging agents.
Deposited CdS nanoparticle films were used in this work as model quantum dot surfaces for ligand adsorption studies. The adsorption of the monothiol-containing ligands, mercaptoacetic acid, mercaptopropionic acid, and mercaptoethanol, to CdS thin films were studied in situ using attenuated total reflectance infrared spectroscopy. The absence of an S-H stretch absorption for the adsorbed species showed that adsorption occurred via the deprotonated thiol group.
The adsorption of the dithiol-containing ligands α-lipoic acid, dihydrolipoic acid, and dithiothreitol to CdS nanoparticle films was investigated. The adsorption of dihydrolipoic acid and dithiothreitol was found to occur via both thiol functional groups and an additional interaction between the carboxylate group and the CdS surface. The adsorption of α-lipoic acid to CdS in the presence of light proceeded with photo-oxidation of the CdS surface and reductive cleavage of the disulfide bond of α-lipoic acid to produce some adsorbed dihydrolipoic acid and thiosulfate. The adsorption of α-lipoic acid to CdS in the absence of visible light showed no photo-oxidation, and suggested adsorption occurred via retention of the disulfide bond.
The kinetics of adsorption and desorption of oxalic acid on deposited anatase TiO₂ films were studied to investigate the feasibility of extracting molecular information from attenuated total reflectance infrared spectroscopic kinetic data of ligand processes on deposited particle films. Oxalic acid adsorbed on anatase TiO₂ is a well-studied example and is reported to result in three different surface species. The profile of the desorption data indicated contributions from three different components. Different component contributions were unable to be obtained from the adsorption data which is attributed to adsorption occurring much faster than desorption and thus being relatively insensitive to the presence of different adsorbed species.
The kinetics of adsorption and desorption of mercaptoacetic acid on CdS were investigated. The desorption data profile indicated the presence of two adsorbed species with different affinities for the CdS surface, the exact chemical nature of which can only be speculated upon given the absence of distinguishing IR spectral features.
Ligand exchange reactions at the surface of oleate and trioctylphosphine oxide-capped CdS quantum dot films were investigated. Adsorbed oleate was coordinated to the CdS in a chelating bidentate manner through the carboxylate functional group, while adsorbed trioctylphosphine oxide was coordinated though the P=O functional group. Ligand exchange reactions on the oleate and trioctylphosphine-capped CdS films were studied, and exchange with monothiol-containing ligands was observed only at solution pH where the exchanging ligand was uncharged.
Avidin-biotin bioconjugation reactions were carried out on CdS films, which involved the sequential adsorption of mercaptoacetic acid, the protein avidin, and the subsequent binding of the ligand biotin. The spectral data suggested that avidin underwent a conformational change upon adsorption to the CdS surface. This conformation appeared to be perturbed again upon binding of biotin, and it is speculated that the conformation partially reverted back to the native solution conformation.
16
Jiang, Tong. "Porous tin(IV) sulfide materials". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0007/NQ41557.pdf.
Testo completo
17
Wilmont, David B. "Sulfide metabolism in thiotrophic symbioses /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p3035920.
Testo completo
18
Marin, Riccardo <1987>. "Copper sulfide and copper indium sulfide nanoparticles: two optically active materials with a bright future". Doctoral thesis, Università Ca' Foscari Venezia, 2017. http://hdl.handle.net/10579/11971.
Testo completoAbstract (sommario):
In questa tesi presento i risultati dello studio di nanoparticelle (NPs) di rame indio solfuro e rame solfuro aventi differenti proprietà ottiche. Questi due materiali sono attualmente sotto meticolosa investigazione, poiché recenti studi li hanno confermati essere delle valide alternative rispetto ai materiali utilizzati al momento in molti campi applicativi. Ciò deriva dalla loro affidabilità, intrinseca non tossicità e dal loro essere relativamente economici. Queste NP possono essere utilizzate per la produzione, tra gli altri, di agenti teranostici, dispositivi fotovoltaici, sensori e LED. Lo scopo della mia ricerca è stato di sintetizzare tali NP con metodi semplici ed innovativi, al fine di impartire a tali NP specifiche caratteristiche, quali la possibilità di essere dispersi in solventi polari o proprietà ottiche migliori. In una seconda fase, ho studiato l’interazione di queste NP con NP a base di terre rare (RE) al fine di ottenere sistemi complessi con proprietà superiori.
19
D\'Imperio, Seth. "Microbial interactions with arsenite, hydrogen and sulfide in an acid-sulfate-chloride geothermal spring". Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/d'imperio/D'ImperioS0508.pdf.
Testo completoAbstract (sommario):
The work presented in this thesis investigated the importance of hydrogen, sulfide and arsenite in microbial community structure and function within a model Acid-Sulfate-Chloride (ASC) spring in Yellowstone National Park. Previous studies in this spring found that microbial arsenite [As(III)] oxidation is absent in regions of the spring outflow channel where H2S exceeds ~5 μM. Ex situ assays with microbial mat samples demonstrated immediate As(III) oxidation activity when H2S was absent or in low concentrations, suggesting the presence of functional As(III) oxidase enzymes in regions of the spring where arsenite oxidation had not been previously observed. Cultivation efforts resulted in the isolation of an As(III)-oxidizing chemolithotroph phylogenetically related to the α-proteobacterium Acidicaldus. H2S concentration appeared to be the most important constraint on spatial distribution of this organism. This was verified with pure culture modeling and kinetic experiments. Additionally, a study is presented that addresses the relative importance of dissolved hydrogen and sulfide for primary production in the same spring. Throughout the outflow channel where these gases could be detected, biological H2S consumption rates exceeded those of H2 by at least three orders of magnitude. Molecular analysis showed that Hydrogenobaculum-like organisms dominate the microbial community in this region of the spring. Culturing efforts resulted in 30 Hydrogenobaculum isolates belonging to three distinct 16S rRNA gene phylotypes. The isolates varied with respect to electron donor (H2S, H2) and oxygen tolerance and requirement. These metabolic physiologies are consistent with in situ geochemical conditions. An isolate representative of the dominant 16S phylotype was used as a model organism for controlled studies to determine whether an organism capable of utilizing either of these substrates demonstrated preference for H2S or H2, or whether either electron donor exerted regulatory effects on the other. The organism studied utilized both H2S and H2 simultaneously and at rates roughly comparable to those measured in the ex situ field assays. Major conclusions drawn from this study are that phylogeny cannot be relied upon to predict physiology, and that, in ASC springs, H2S clearly dominates H2 as an energy source, both in terms of availability and apparent consumption rates.
20
Dhakal, Prakash Saunders James A. "Sorption of arsenic by iron sulfide made by sulfate-reducing bacteria implications for bioremediation /". Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/FALL/Geology_and_Geography/Thesis/Dhakal_Prakash_27.pdf.
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Mihajlovic, Aleksandra. "Antidotal mechanisms for hydrogen sulfide toxicity". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0001/MQ45417.pdf.
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22
Horak, Rachel Elizabeth Ann. "Do Sulfide-Oxidizing Bacteria Produce Light?" W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539626456.
Testo completo
23
Ha, Junghoon. "Hydrogen Sulfide Regulation of Kir Channels". VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5204.
Testo completoAbstract (sommario):
Inwardly rectifying potassium (Kir) channels establish and regulate the resting membrane potential of excitable cells in the heart, brain and other peripheral tissues. Phosphatidylinositol- 4,5-bisphosphate (PIP2) is a key direct activator of ion channels, including Kir channels. Gasotransmitters, such as carbon monoxide (CO), have been reported to regulate the activity of Kir channels by altering channel-PIP2 interactions. We tested, in a model system, the effects and mechanism of action of another important gasotransmitter, hydrogen sulfide (H2S) thought to play a key role in cellular responses under ischemic conditions. Direct administration of sodium hydrogen sulfide (NaHS), as an exogenous H2S source, and expression of cystathionine γ-lyase (CSE), a key enzyme that produces endogenous H2S in specific brain tissues, resulted in comparable current inhibition of several Kir2 and Kir3 channels. A “tag switch” assay provided biochemical evidence for sulfhydration of Kir3.2 channels. The extent of H2S regulation depended on the strength of channel-PIP2 interactions: H2S regulation was attenuated when strengthening channel-PIP2 interactions and was increased when channel-PIP2 interactions were weakened by depleting PIP2 levels via different manipulations. These H2S effects took place through specific cytoplasmic cysteine residues in Kir3.2 channels, where atomic resolution structures with PIP2 gives us insight as to how they may alter channel-PIP2 interactions. Mutation of these residues abolished H2S inhibition, and reintroduction of specific cysteine residues into the background of the mutant lacking cytoplasmic cysteine residues, rescued H2S inhibition. Molecular dynamics simulation experiments provided mechanistic insights as to how sulfhydration of specific cysteine residues could lead to changes in channel-PIP2 interactions and channel gating.
24
McGinnity, Justin. "Sulfur dioxide leaching of zinc sulfide". Thesis, Curtin University, 2001. http://hdl.handle.net/20.500.11937/1033.
Testo completoAbstract (sommario):
Studies were conducted into the mechanism and kinetics of the dissolution of synthetic zinc sulfide and zinc concentrate in aqueous solutions containing sulfur dioxide.Experiments at ambient temperature established that the dissolution of ZnS in aqueous solutions of sulfur dioxide proceeds via acidic non-oxidative dissolution and not by direct reaction of the sulfide with S02(aq). The non-oxidative dissolution reaction generates H2S(aq) or HS-(aq) species which are thought to rapidly react with sulfurous acid species, S02(aq) or HS03-(aq), to possibly produce initially sulfane monosulfonates as intermediates, followed by sulfane disulfonates and elemental sulfur. The formation of sulfane monosulfonates is postulated based upon inhibition observed in ZnS / S02 leaches which is not attributable to either H2S(aq) or occlusion elemental sulfur.At elevated temperatures (100oC - 200oC) the rate of ZnS dissolution in sulfurous acid is affected by the thermal decomposition of sulfurous acid, which produces sulfuric acid, which leaches the mineral non-oxidatively. Increasing the temperature increases the rate of thermal decomposition of sulfurous acid and consequently, the rate of sulfuric acid formation, increasing the rate of ZnS dissolution.The kinetics of the dissolution of ZnS in solutions of sulfuric acid and sulfur dioxide were investigated at temperatures up to 200oC. At 100oC and 150oC, the dissolution of ZnS in H2SO4 was found to obey the relationd[Zn2+]/dt = kfAs[H+] krAs[H2S(aq)]1/2[Zn2+]1/2and equilibria and rate constants for the ZnS / H2S04 reaction were obtained over the range, 100oC to 200oC. The activation energies of the forward and reverse reactions were found to be 56 +/- 11 kJ mol-1 and 45 +/- 15 kJ mol-1, respectively. The equilibrium constants were 4.99x10-4, 1.26x10-3 and 2.83x10-3 at 100oC, 150oC and 200oC, respectively.In the presence of added S02, at low ZnS pulp density (0.5 g L-1), the rate of ZnS dissolution in sulfuric acid increased due to the removal of H2S(aq) by reaction with S02(aq) or HS03-(aq). However the increase in rate was much less than that expected for the complete removal of H2S(aq). As with leaches of ZnS in sulfurous acid at ambient temperature, the inhibition was not attributable to the presence of residual H2S(aq) or to occlusion of unreacted ZnS by elemental sulfur, but is thought to be due to aqueous species that are like "H2S", in that they may react with Zn2+ to reprecipitate W.To this end, sulfane monosulfonates have again been postulated. The rate of ZnS dissolution, under conditions of low pulp density, was independent Of S02 concentration, suggesting that under these conditions the rate of the H2S / S02 reaction is also independent of the S02 concentration.At higher pulp densities (200 g L-1), similar to those expected in an industrial application, synthetic zinc sulfide leached rapidly in H2S04 / S02 solutions to approximately 60% zinc extraction, but was then inhibited by the large amounts of sulfur that formed. These caused agglomerates of zinc sulfide and elemental sulfur to form, even at temperatures below the melting point of sulfur, reducing the surface area of zinc sulfide available for reaction.Leaches of zinc concentrate at low pulp densities in H2S04 / S02 solutions and at temperatures above sulfur's meting point, were inhibited by the formation of molten sulfur. In contrast to synthetic zinc sulfide, zinc concentrate is readily wet by molten sulfur. Three surfactants orthophenylenediamine, quebracho and sodium ligninsulfonate were found to be reasonably effective in preventing molten sulfur from occluding the mineral surface. At high pulp densities, the H2S04 / S02 leach solution was unable to effect, the extraction of zinc from a zinc concentrate beyond approximately 10%.Integral S02 / H2S04 leaching of zinc concentrate was found not to be a commercial prospect. However, sidestream processing of zinc concentrate in an acid leach stage followed by reaction of generated H2S with S02 from the roasting stage to produce elemental sulfur may be viable.
25
McGinnity, Justin. "Sulfur dioxide leaching of zinc sulfide". Curtin University of Technology, Department of Applied Chemistry, 2001. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=12896.
Testo completoAbstract (sommario):
Studies were conducted into the mechanism and kinetics of the dissolution of synthetic zinc sulfide and zinc concentrate in aqueous solutions containing sulfur dioxide.Experiments at ambient temperature established that the dissolution of ZnS in aqueous solutions of sulfur dioxide proceeds via acidic non-oxidative dissolution and not by direct reaction of the sulfide with S02(aq). The non-oxidative dissolution reaction generates H2S(aq) or HS-(aq) species which are thought to rapidly react with sulfurous acid species, S02(aq) or HS03-(aq), to possibly produce initially sulfane monosulfonates as intermediates, followed by sulfane disulfonates and elemental sulfur. The formation of sulfane monosulfonates is postulated based upon inhibition observed in ZnS / S02 leaches which is not attributable to either H2S(aq) or occlusion elemental sulfur.At elevated temperatures (100oC - 200oC) the rate of ZnS dissolution in sulfurous acid is affected by the thermal decomposition of sulfurous acid, which produces sulfuric acid, which leaches the mineral non-oxidatively. Increasing the temperature increases the rate of thermal decomposition of sulfurous acid and consequently, the rate of sulfuric acid formation, increasing the rate of ZnS dissolution.The kinetics of the dissolution of ZnS in solutions of sulfuric acid and sulfur dioxide were investigated at temperatures up to 200oC. At 100oC and 150oC, the dissolution of ZnS in H2SO4 was found to obey the relationd[Zn2+]/dt = kfAs[H+] krAs[H2S(aq)]1/2[Zn2+]1/2and equilibria and rate constants for the ZnS / H2S04 reaction were obtained over the range, 100oC to 200oC. The activation energies of the forward and reverse reactions were found to be 56 +/- 11 kJ mol-1 and 45 +/- 15 kJ mol-1, respectively. The equilibrium constants were 4.99x10-4, 1.26x10-3 and 2.83x10-3 at 100oC, 150oC and 200oC, respectively.In the presence of added S02, ++at low ZnS pulp density (0.5 g L-1), the rate of ZnS dissolution in sulfuric acid increased due to the removal of H2S(aq) by reaction with S02(aq) or HS03-(aq). However the increase in rate was much less than that expected for the complete removal of H2S(aq). As with leaches of ZnS in sulfurous acid at ambient temperature, the inhibition was not attributable to the presence of residual H2S(aq) or to occlusion of unreacted ZnS by elemental sulfur, but is thought to be due to aqueous species that are like "H2S", in that they may react with Zn2+ to reprecipitate W.To this end, sulfane monosulfonates have again been postulated. The rate of ZnS dissolution, under conditions of low pulp density, was independent Of S02 concentration, suggesting that under these conditions the rate of the H2S / S02 reaction is also independent of the S02 concentration.At higher pulp densities (200 g L-1), similar to those expected in an industrial application, synthetic zinc sulfide leached rapidly in H2S04 / S02 solutions to approximately 60% zinc extraction, but was then inhibited by the large amounts of sulfur that formed. These caused agglomerates of zinc sulfide and elemental sulfur to form, even at temperatures below the melting point of sulfur, reducing the surface area of zinc sulfide available for reaction.Leaches of zinc concentrate at low pulp densities in H2S04 / S02 solutions and at temperatures above sulfur's meting point, were inhibited by the formation of molten sulfur. In contrast to synthetic zinc sulfide, zinc concentrate is readily wet by molten sulfur. Three surfactants orthophenylenediamine, quebracho and sodium ligninsulfonate were found to be reasonably effective in preventing molten sulfur from occluding the mineral surface. At high pulp densities, the H2S04 / S02 leach solution was unable to effect, the extraction of zinc from a zinc concentrate beyond approximately ++
10%.Integral S02 / H2S04 leaching of zinc concentrate was found not to be a commercial prospect. However, sidestream processing of zinc concentrate in an acid leach stage followed by reaction of generated H2S with S02 from the roasting stage to produce elemental sulfur may be viable.
26
DI, MEO IVANO. "Altered Sulfide Metabolism in Ethylmalonic Encephalopathy". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/29887.
Testo completoAbstract (sommario):
Ethylmalonic Encephalopathy, EE, is an autosomal recessive, invariably fatal disorder characterized by early-onset brain failure, microangiopathy, chronic diarrhoea, defective cytochrome c oxidase (COX) in muscle and brain, and high excretion of ethylmalonic acid (EMA) in urine. ETHE1, a gene encoding a mitochondrial beta-lactamase-like, iron-coordinating metalloprotein, is mutated in EE. We generated an Ethe1-null mouse that manifested the EE cardinal features. We found that thiosulfate was excreted in massive amount in urines of both Ethe1-/- mice and EE patients. High thiosulfate (H2SSO3) and sulfide (H2S) levels were present in Ethe1-/- mouse tissues. Sulfide is a powerful inhibitor of COX and terminal beta-oxidation, with vasoactive and vasotoxic effects that could explain the microangiopathy in EE patients. Sulfide is detoxified by a mitochondrial pathway that includes a sulfur dioxygenase (SDO). SDO activity was absent in Ethe1-/- mice, whereas ETHE1 overexpression in HeLa cells and E. coli markedly increased it. Therefore, ETHE1 is a mitochondrial SDO involved in catabolism of sulfide, which accumulates to toxic levels in EE.
An important question that warranted the PhD experimental work concerns the source of H2S in ETHE1 mutant patients, and how accumulated sulfide can act on the cytochrome c oxidase complex at molecular level. The presence of elevated levels of thiosulfate in several tissues of the Ethe1-/- mouse suggests endogenous production of H2S from catabolism of cysteine and other sulfur-containing organic compounds. H2S is also a major product of the intestinal bacterial flora, especially anaerobic species residing in the colon. The presence of a gradient of COX deficiency in luminal vs. cryptal colonocytes in Ethe1-/- colon mucosa suggests that a defect of ETHE1-SDO activity results in faulty detoxification of exogenously produced H2S. In order to achieve effective reduction of H2S production, it is crucial to clarify which are the sources of this compound in the body that can then constitute specific targets for therapy. Another important issue is to understand the organ-specific mechanisms, which lead to failure of some organs, such as the brain and the skeletal muscle, but not of others, such as the liver. These aims can be implemented through the creation and characterization of conditional tissue-specific KO animals.
A further research line concerns the improvement of biochemical and molecular approaches for the diagnosis of EE.
27
Steiger, Andrea. "Self-Immolative Thiocarbamates for Studying COS and H2S Chemical Biology". Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24522.
Testo completoAbstract (sommario):
In recent years, hydrogen sulfide (H2S) has garnered interest as the third addition to the gasotransmitter family. Essential to human physiology, H2S has roles in the cardiovascular, nervous, and respiratory systems and perturbations in physiological H2S levels have been correlated to a variety of diseases. As a result, there has been significant interest in the development of H2S-releasing compounds (H2S donors) that can mimic slow, enzymatic production for research and therapeutic applications. While a large library of H2S donors exists, several common drawbacks persist, such as: lack of spatial and temporal control, poorly understood mechanisms of release, uncontrolled kinetics, and low efficiency. These issues significantly limit the biological applications of many H2S donors.
This dissertation describes recent work to provide biocompatible H2S donors with controllable release kinetics using a robust, novel strategy for H2S delivery that relies on rapid enzymatic hydrolysis of carbonyl sulfide (COS) to H2S by the ubiquitous mammalian enzyme carbonic anhydrase (CA). Self-immolative thiocarbamates can be designed to release COS by a variety of stimuli, and in biological milieu this COS is rapidly converted to H2S by CA. This strategy has enabled the development of the first analyte-replacement fluorescent probe for H2S and has become a popular strategy for H2S delivery in a variety of applications. Additionally, the unexpected cytotoxicity profile of enzyme-activated COS/H2S donors has piqued interest in COS chemical biology, and these donors are being used as tools for studying COS itself. This dissertation includes previously published and unpublished coauthored work.2021-04-30
28
Polo, Christy Beatriz Carolina. "Effect of hydraulic retention time and attachment media on sulfide production by sulfate reducing bacteria". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62266.pdf.
Testo completo
29
Wang, Daguang 1958. "Synthesis of oligonucleotides containing a sulfide or sulfone backbone for binding & nuclease stability studies". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41130.
Testo completoAbstract (sommario):
Thymidine dinucleoside 58 (TsT) and 62 containing a dialkyl sulfide or sulfone backbone, as well as thymidine and 2$ sp prime$-O-methyluridine dinucleoside 76 containing a dialkyl sulfide backbone have been synthesized. Dimer 58 has been shown to be easily incorporated into DNA by standard automated methodology giving oligomer 2.The synthesis of "5$ sp prime$-end unit" 49, "repeating unit" 33 and "3$ sp prime$-end unit" 54 and 71 are described.
The 2-(trimethylsilyl)ethoxymethyl chloride (SEM) was used for the protection of imide group of uridine. The removal of the SEM group is similar to that of other silyl protecting groups and only needs a somewhat higher temperature. (Abstract shortened by UMI.) ftn*Please refer to the dissertation for diagrams.
30
White, Richard James. "Synthesis and characterisation of complex sulfide materials with potential use as high temperature inorganic sulfide-ion conductors". Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7824.
Testo completo
31
Ehm, Lars. "Hochdruckpulverdiffraktometrie an Sulfid- und Halogenid-Schichtstrukturen". [S.l.] : [s.n.], 2003. http://e-diss.uni-kiel.de/diss_766/d766.pdf.
Testo completo
32
Chaganti, Venkata R. "Study of the structural and spectroscopic properties of small ZnS clusters by DFT". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2008. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Testo completo
33
Liu, Yongning. "Synthesis and Characterization of New Aryl Phosphine Oxide and Ketone Containing Poly(arylene Sulfide Sulfone)s". Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30744.
Testo completoAbstract (sommario):
High molecular weight poly(phenylene sulfide sulfone) (PPSS) homo- and statistical copolymers have been reproducably synthesized using a known, but complex procedure utilizing 4,4'-dichlorodiphenyl sulfone (DCDPS), sodium hydrosulfide, sodium hydroxide, sodium acetate, and deionized water, in NMP at elevated reaction temperatures and pressure. The effect of these variations, e.g., reaction temperatures and times, molar ratios of H2O-to-NaSH, NMP-to-H2O, etc. were investigated. Optimized conditions were defined, which produced Tg as high as 222°C, very high refractive index (1.70), and tough/solvent resistant films could be prepared by melt fabrication. A two-stage decomposition mechanism in air was demonstrated by dynamic thermal gravimetric analysis.
The melt stability of PPSS was improved by incorporating thermally stable endgroups, such as diphenyl sulfone, 4-chlorophenylphenyl sulfone, and t-butylphenoxide. The chemical structures of the endgroups were confirmed by 13C and 1H NMR spectra. Compared with mercaptide endcapped PPSS, the new systems showed higher initial degradation temperatures (2% and 5% weight loss), higher char yield at 650°C in air and a more stable melt viscosity at 300°C.
A greatly simplified synthesis of both homo and copolymers has been successfully developed using the new A-A or A-B type thiol-functional monomers, such as bis-(4-mercaptophenyl) sulfone, 4-chloro-4'-mercaptodiphenyl sulfone and 4-chloro-4'-mercapto benzophenone, instead of sodium hydrosulfide. A series of high molecular weight triphenyl phosphine oxide and/or diphenyl ketone containing PPSS copolymers were subsequently synthesized from the bis-(4-mercaptophenyl) sulfone by reaction with 4,4'-dichlorodiphenyl sulfone, bis-(4-fluorophenyl) phenyl phosphine oxide, and 4,4'-difluorobenzophenone in DMAc in the presence of K2CO3 at 160°C. The new phosphine oxide containing PPSS copolymers were completely amorphous, showed improved solubility in common organic solvents and exhibited very high char yields in air at 750°C. Surface (XPS) analysis results suggested that the phosphorus moieties in the polymer backbone can form phosphate-like layers on the polymer surface which protects the inner materials from further decomposition in air at high temperatures. The diphenyl ketone containing PPSS copolymers showed very high char yields at 750°C in a nitrogen atmosphere, compared to sulfide sulfone homopolymer and phosphine oxide containing copolymers, possibly because of higher bond energies.
Semi-crystalline poly(phenylene sulfide ketone) homopolymers and sulfone containing copolymers with sulfone/ketone mole ratio (S : K) < 25 : 75 were synthesized by a novel base catalyzed self-polycondensation of 4-chloro-4'-mercaptodiphenyl sulfone and/or 4-chloro-4'-mercapto benzophenone in N-cyclohexyl-2-pyrrolidinone (CHP) at 290°C. Amorphous copolymers with S : K ratios > 25 : 75 were prepared in DMAc at 160°C. These materials exhibited an increase in glass transition temperature with increasing sulfone content. TGA and micro cone calorimetry analyses showed that the semi-crystalline materials with high ketone content had much higher char yields and significantly lower heat release rate and total heat release, compared to the poly(phenylene sulfide sulfone) and poly(pheylene sulfide) controls.Ph. D.
34
Hall, Donald Lewis. "Fluid evolution during metamorphism and uplift of the massive sulfide deposits at Ducktown, Tennessee, U.S.A". Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54186.
Testo completoAbstract (sommario):
The Ducktown mining district, located in the southeastern corner of Tennessee within the Blue Ridge Province of the southern Appalachians, contains some of the largest metamorphosed pyrrhotite-pyrite-rich massive sultide deposits in the Appalachian-Caledonian orogen. Oxygen isotope temperatures of 530±20°C are consistent with previous estimates based on mineral thermobarometers (540±40°C; 6-7 kb) suggesting that minerals attained oxygen isotopic equilibrium during peak metamorphism and underwent little retrograde exchange. Fluid inclusion and petrologic data do not support the previous interpretation that low δ¹⁸O zones near orebodies are synmetamorphic, rather, a premetamorphic origin is indicated. Integrated fluid/rock ratios were low enough during and after metamorphism that premetamorphic spatial variations in δ¹⁸O were retained. However, hydrogen and carbon isotopes were homogenized throughout the area during or before metamorphism. The low δ¹⁸O zones surrounding the orebodies appear to have formed during sea—fIoor hydrothermal activity associated with ore deposition. The δ¹⁸O value of the fluid responsible for ore deposition, assuming a temperature of 300°C, is calculated to be -1 to +2 per mil, consistent with the interpretation that the ore fluid was modified seawater.
Calculation of theoretical C-O-H-S fluid speciation suggests that the fluid in equilibrium with clinopyroxene-bearing rocks was essentially H₂O+CO₂with XCO₂ = 0.10. However, primary fluid inclusions located in clinopyroxene contain signifticant quantities of CH₄. This discrepancy is explained by hydrogen diffusion into primary fluid inclusions and subsequent conversion of CO₂ to CH₄ during uplift in response to an fH₂ gradient between inclusion and matrix fluids. Low δD values of primary fluid inclusions are consistent with diffusive addition of isotopically light hydrogen after trapping.
Secondary inclusions in metamorphic quartz record a complex uplift history involving a variety of fluids in the C-O-H-N-salt system. lsochores calculated for these inclusions constrain the uplift path to have been initially concave toward the temperature axis. Over the pressure range 2.3 to 1.0 kb the uplift path became nearly isothermal at 215±20°C. lmmiscible H₂O-CH₄-N₂-NaCl fluids present during the isothermal stage of the uplift history were derived during Alleghanian thrusting by expulsion of pore fluids and maturation of organic matter in lower plate sedimentary rocks proposed to underlie the deposits. Average uplift rates of 0.1 mm/yr are suggested by the uplift path and available geochronologic data.Ph. D.
35
Ferrera, Ceada Isabel. "Development and characterization of sulfide-oxidizing biofilms". Doctoral thesis, Universitat Autònoma de Barcelona, 2004. http://hdl.handle.net/10803/3876.
Testo completoAbstract (sommario):
En el present treball s'han desenvolupat i caracteritzat biofilms per a la detoxificació d'efluents contaminats amb compostos reduïts de sofre. En primer lloc es va dissenyar un bioreactor basat en una columna il·luminada que aporta una gran i heterogènia superfície d'adhesió per als microorganismes, i en el qual no hi ha aportació externa d'oxigen. El sistema de control, basat en el potencial redox, permet mantenir constant la concentració residual de sulfur d'hidrogen en el rang micromolar, evitant la inhibició dels microorganismes i mantenint al mateix temps la qualitat de l'efluent generat.S'han realitzat tres experiments per tal de provar el sistema, el primer amb un cultiu pur de Chlorobium limicola, i després amb mostres naturals (sediment lacustre i tapet microbià) per tal d'aconseguir biofilms complexos. Els biofilms es desenvolupen ràpidament assolint-se una elevada biomassa en tots els casos. El comportament dinàmic del sistema és més lent que el dels sistemes de biomassa en suspensió, però alhora més estable a les pertorbacions. De fet, el sistema és capaç de mantenir l'oxidació de sulfurs i la qualitat de l'efluent generat fins i tot quan les condicions de llum incident o de concentració de sulfur d'hidrogen a l'entrada del sistema canvien.
S'han caracteritzat els biofilms complexos amb eines clàssiques (microscopi i anàlisi de pigments) i també amb eines moleculars (biblioteques genètiques). En primer lloc, s'han avaluat diferents mètodes d'extracció d'ADN per tal de trobar el millor per a les nostres mostres. S'ha comparat l'eficiència d'extracció quantificant l'ADN obtingut, i la diversitat recuperada en cada mètode amb electroforesi en gels de gradient desnaturalitzant (DGGE). El mètode basat en un trencament mecànic amb microesferes de vidre seguit d'una lisi enzimàtica i una extracció amb fenol és el més apropiat per a l'extracció d'aquests biofilms.
La caracterització del biofilms ha revelat una elevada diversitat microbiana tant a nivell filogenètic com fisiològic. Ambdós biofilms presenten una gran riquesa d'espècies així com un elevat grau de microdiversitat entre alguns grups. S'observen algunes diferències en els grups filogenètics predominants entre els dos biofilms. S'han recuperat membres relacionats amb les subclasses Alpha i Gamma del grup Proteobacteria, amb el grup Cytophaga-Flavobacterium-Bacteroides així com amb cloroplasts d'algues en ambdós biblioteques genètiques. A més, en el biofilm desenvolupat a partir del sediment lacustre, també s'han trobat membres de les subclasses Beta i Delta-Proteobacteria, del grup Cianobacteria i dels bacteris Gram-positius de baix contingut en G+C (Firmicutes). Per contra, la biblioteca realitzada amb el biofilm desenvolupat a partir del tapet microbià conté una elevada proporció de clons relacionats amb les Epsilon-Proteobacteria i amb els Chlorobi. Tot i que els membres trobats pertanyent a tots aquests grups filogenètics són diferents, representen els mateixos grups funcionals. El sulfhídric era oxidat anaeròbicament pels bacteris fototròfics del sofre i els bacteris vermells no del sofre, i aeròbicament pels bacteris quimiolititròfics del sofre utilitzant l'oxigen produït pels organismes fototròfics oxigènics. Altres microorganismes com els bacteris heterotròfics podrien contribuir al funcionament del sistema a través del reciclatge de la matèria orgànica.
En conclusió, trobem una elevada diversitat tant a nivell funcional com taxonòmic en els biofilms desenvolupats. Diferents grups funcionals representats per diferent espècies (heterotròfiques, fotoautotròfiques i quimioautotròfiques) coexisteixen al sistema. A més, també trobem microdiversitat (similitud per sobre del nivell d'espècie en la seqüència del gen 16S ADNr). Aquesta elevada diversitat podria ser molt important per al funcionament a llarg termini del reactor.
This works deals with the development and characterization of complex sulfide-oxidizing biofilms. A bioreactor for biofilm development has been designed. The system is based on a non-aerated illuminated packed-column, which provides a large surface for microbial attachment. The reactor operates as a sulfidostat and the control system allows to maintain a constant concentration of residual sulfide in the micromolar range thus avoiding inhibition of sulfide oxidizers due to excessive sulfide load and ensuring a constant quality in the effluent.
The system was first tested with a pure culture of Chlorobium limicola and, later on, with natural samples (freshwater lake sediment and a microbial mat) in order to develop complex biofilms. Biofilms developed vigorously on the column surface and high biomass was achieved in all the experiments. The dynamic behavior of the system was slower than in stirred reactors but more stable in front of sudden environmental changes. The system was able to process highly polluted effluents and to maintain the quality of the output generated even when conditions of light irradiance and sulfide income were suddenly changed.
The biofilms developed were characterized using both, traditional techniques (i.e. microscopy and pigment analysis) and a molecular approach, in particular cloning and sequencing. First, of all, several DNA extraction procedures were evaluated in order to select the most suitable method for performing the diversity analysis of our biofilms. We compared the extraction efficiency (i.e. amount of DNA recovered), as well as the genetic diversity recovered by denaturing gradient gel electrophoresis (DGGE). A DNA extraction based on a mechanical step of bead-beating followed by enzymatic lysis and by phenol-chloroform extraction, was the most appropriate protocol for these biofilms.
Microbial characterization revealed that, in both cases, highly diverse biofilms covering a wide range of phylogenetic and physiologic groups had developed. Both biofilms presented high species richness and a high degree of microdiversity within some species. Some differences were observed in the predominant phylogenetic groups present in each biofilm. We recovered members affiliated to the Alpha and Gamma subclass of the Proteobacteria, the Cytophaga-Flavobacterium-Bacteroides group as well as plastids signatures from green algae in both biofilm libraries. Moreover, in the biofilm developed from the freshwater sample, other clones belonged to the Beta- and Delta-Proteobacteria, the Cyanobacteria and the low G+C Gram-positive whereas we recovered clones belonging to the Epsilon-Proteobacteria and to the Chlorobi only from the marine biofilm. Although members belonging to these phylogenetic groups were different in each case, they represented the same functional groups. Sulfide was oxidized both anaerobically by phototrophic sulfur bacteria and by purple nonsulfur bacteria, and aerobically by colorless sulfur bacteria using the oxygen produced by oxygenic phototrophs, as the system was non-aerated. Other groups, such heterotrophic bacteria, can also contribute to the functioning of the system by recycling organic matter.
In conclusion, we found high diversity at both functional and taxonomic level. Different functional groups represented by different species (heterotrophic, photoautotrophic and chemoautotrophic microorganisms) coexisted in the bioreactor. Moreover, some of the species also showed microdiversity (similarity in 16S rDNA sequences below the species level). Such attributes could be very important for the long-term functioning and versatility of the reactor.
36
Beauvais, Jacques. "Gain optique dans le cadmium indium sulfide". Thesis, University of Ottawa (Canada), 1987. http://hdl.handle.net/10393/5316.
Testo completo
37
Bower, Julia Michelle. "Immobilization of mercury using iron sulfide minerals". Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/BOWER_JULIA_20.pdf.
Testo completo
38
Alshawa, Amer. "AC electroluminescence in thulium-doped zinc sulfide". Ohio : Ohio University, 1988. http://www.ohiolink.edu/etd/view.cgi?ohiou1182778578.
Testo completo
39
Stevenson, Ross Kelley. "Implications of amazonite to sulfide-silicate equilibria". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63377.
Testo completo
40
El, Husseini Bassam. "Streaming potential measurements in sulfide rich tailings". Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115872.
Testo completoAbstract (sommario):
In general, tailings dams are expected to seep. Anomalous seepage, especially when induced by internal erosion, is a major concern for owners and operators. The long established techniques for monitoring water seepage provide sparse information which may not be sufficient to detect and map the seepage path. Hence, there exists a great need for non-invasive techniques that would be sensitive to changing seepage conditions. The non-invasive nature of the techniques is particularly important because drilling and other penetrating (invasive) investigation methods are normally avoided.Non-invasive techniques such as self-potential and high-resolution resistivity have been significantly improved in the past decade and have been successfully used for water retention dam investigation and monitoring. The main difficulty in the use of these techniques in monitoring sulfide rich tailings dams is the presence of electrochemical potentials that renders the interpretation of the acquired self-potential data difficult.
Numerical modelling is one of the latest methods in interpreting self-potential anomalies induced by liquid flow. But, in order to model streaming potentials several parameters need to be measured or estimated; (1) the hydraulic driving force and the hydraulic conductivity are required to solve for the hydraulic pressure distribution; (2) the cross-coupling conductivity distribution is needed to calculate the conduction current source parameter; and (3) the resistivity distribution is needed to determine the resulting potential distribution.
The zeta-potential and the resistivity of three pyrite rich tailings from the Abitibi region in Quebec were measured over the pH range 2 to 5 in different KCl aqueous solutions for the purpose of estimating the magnitude of electrokinetic effect induced by mine water seepage and the electrical resistivity variation induced by particle migration. The experimental and theoretical results obtained in the present study are pertinent to the interpretation of self-potential data. The zeta-potential was found to vary from -27 to -2 mV and the resistivity of the tailings was found to increase when fine particles are eroded.
41
Goedel, Karl Christoph. "Optoelectronic applications of solution-processable sulfide semiconductors". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/268085.
Testo completoAbstract (sommario):
Solar cells and photodetectors rely on similar physical principles based on the interaction of light and matter. Both types of optoelectronic devices are indispensable in a wide range of technological applications, from large-scale renewable power conversion to everyday consumer items. In this thesis, the use of facile solution-processable semiconductors in solar cells and light sensors is studied with a focus on antimony sulfide (Sb₂S₃) and antimony sulfoiodide (SbSI). The improvement of the photovoltaic performance in Sb₂S₃ sensitized solar cells upon the controlled partial oxidation of the absorber layer is investigated. A reduction in charge carrier recombination is the reason for the improved efficiency, caused by the oxidation process. Further, a new chemical bath deposition method for antimony sulfide is developed. Carried out at room temperature, this technique eliminates the necessity of cooling equipment during the deposition process. The antimony sulfide from this method decreases the density of trap states compared to the conventional deposition. Power-conversion efficiencies of up to η=5.1% are achieved in antimony sulfide sensitised solar cells using the new room temperature deposition method. Finally, antimony sulfide is used as a precursor to form films of antimony sulfoiodide (SbSI) micro-crystals in a facile physical vapour process. These films are then used to fabricate photodetectors. With PMMA as an insulating spacer layer, the devices are built in a sandwich-type architecture. Optoelectronic characterisation shows that these devices have the shortest response and recovery times reported for SbSI photodetectors to date.
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Fisher, Duncan Southam. "Chemical weathering of sulfide mineralization on Mars". Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/52911.
Testo completoAbstract (sommario):
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1990.Includes bibliographical references (leaves 68-76).
by Duncan Southam Fisher.
M.S.
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Hettula, J. (Jesse). "Pyhäsalmi volcanogenic massive sulfide deposit, central Finland". Bachelor's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201710253010.
Testo completoAbstract (sommario):
Pyhäsalmi mine is located in central Finland, at the eastern side of the Pyhäjärvi lake. The Pyhäsalmi deposit is polymetallic Zn-Cu VMS ore body with total reserve, mined and yet to be mined, of 58.3 Mt @ Cu 0.9 %, Zn 2.4 %, S 37.8 %, Au 0.4 g/t and Ag 14 g/t. At the end of 2013, 51 Mt of ore has been mined. The mine will be in operation until August of 2019.
The Pyhäsalmi deposit is hosted in a felsic-dominated bimodal Proterozoic succession. Local hydrothermal alteration is composed of sericite-quartz alteration, and intensifies when it is in close proximity with the upper ore body. The deep ore body is thrusted into unaltered metamorphosed hangingwall volcanic rock, thus separated from the alteration zone.
The Pyhäsalmi district and deposit has been subjected to four different tectonic phases (D1–D4) and intrusions accompanied by them. These tectonic processes have thrusted the deposit in upright position from the original position.
Basic theory of VMS formation processes can be used for modeling Pyhäsalmi deposit formation process, which in turn can benefit massive sulfide exploration.
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Wise, William R., Andrew D. Ballantyne e Anthony D. Covington. "Sulfide unhairing - 228: rethinking the received wisdom". Verein für Gerberei-Chemie und -Technik e. V, 2019. https://slub.qucosa.de/id/qucosa%3A34195.
Testo completoAbstract (sommario):
Content:
The removal of hair from a hide or skin by dissolving it with a mixture of lime and sulfide is a fundamentally understood feature of leather technology. Or is it?
For a long time, it has been accepted within the leather literature that, in water, sulfide may be present as either hydrogen sulfide (H2S), hydrosulfide (HS-) or sulfide (S2-), depending on the pH.
pH < 6 6 < pH < 12 pH > 12
H2S(aq) ⇌ HS-(aq) ⇌ S2-(aq)
The generally accepted mechanism of hair burning is sulfide attack at the cystine disulfide linkages in keratin. Also, it is believed that the unhairing reaction only proceeds at an appreciable rate in the presence of the dianionic S2- species, because that fits with the technological observation that unhairing reactions only proceed at pH greater than 12.
However, recent publications have provided substantive proof that the S2- species does not exist in aqueous media at any pH: researchers were unable to observe any evidence of the S2- species in a solution of Na2S dissolved in hyper-concentrated NaOH and CsOH using Raman spectroscopy. The assigned second pKa for removal of the second proton has now been estimated to be 19, making the concentration of S2-(see below) vanishingly small.
HS- ⇋ S2- + H+
There is a clear contradiction between the currently accepted mechanism for sulfide unhairing with the
evidenced speciation of sulfide species in aqueous environment. Here the implications for this important
process are discussed and possible alternative mechanisms postulated that fit with the new knowledge.
Take-Away:
It is a truism that we must understand the mechanistic principles of a process in order to control it. Here, we have a big change in thinking for ‘sulfide unhairing’, so it is vital that we understand the implications for leather science and leather technology of that change.
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De, Almeida Rodrigues Andreia. "Concrete deterioration due to sulfide-bearing aggregates". Doctoral thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/26812.
Testo completoAbstract (sommario):
Dans la région de Trois-Rivières (Québec, Canada), plus de 1 000 bâtiments résidentiels et commerciaux montrent de graves problèmes de détérioration du béton. Les problèmes de détérioration sont liés à l'oxydation des sulfures de fer incorporés dans le granulat utilisé pour la confection du béton. Ce projet de doctorat vise à mieux comprendre les mécanismes responsables de la détérioration de béton incorporant des granulats contenant des sulfures de fer, et ce afin de développer une méthodologie pour évaluer efficacement la réactivité potentielle de ce type de granulats. Un examen pétrographique détaillé de carottes de béton extraites de fondations résidentielles montrant différents degré d’endommagement a été réalisé. Le granulat problématique contenant des sulfures de fer a été identifié comme un gabbro à hypersthène incorporant différentes proportions (selon les différentes localisations dans les deux carrières d’origine) de pyrrhotite, pyrite, chalcopyrite et pentlandite. Les produits de réaction secondaires observés dans les échantillons dégradés comprennent des formes minérales de "rouille", gypse, ettringite et thaumasite. Ces observations ont permis de déterminer qu’en présence d'eau et d'oxygène, la pyrrhotite s’oxyde pour former des oxyhydroxides de fer et de l'acide sulfurique qui provoquent une attaque aux sulfates dans le béton. Tout d'abord, la fiabilité de l'approche chimique proposée dans la norme européenne NF EN 12 620, qui consiste à mesurer la teneur en soufre total (ST, % en masse) dans le granulat pour détecter la présence (ou non) de sulfures de fer, a été évaluée de façon critique. Environ 50% (21/43) des granulats testés, représentant une variété de types de roches/lithologies, a montré une ST > 0,10%, montrant qu'une proportion importante de types de roches ne contient pas une quantité notable de sulfure, qui, pour la plupart d’entre eux, sont susceptibles d'être inoffensifs dans le béton. Ces types de roches/granulats nécessiteraient toutefois d'autres tests pour identifier la présence potentielle de pyrrhotite compte tenu de la limite de ST de 0,10 % proposée dans les normes européennes. Basé sur une revue exhaustive de la littérature et de nombreuses analyses de laboratoire, un test accéléré d’expansion sur barres de mortier divisé en deux phases a ensuite été développé pour reproduire, en laboratoire, les mécanismes de détérioration observés à Trois-Rivières. Le test consiste en un conditionnement de 90 jours à 80°C/80% RH, avec 2 cycles de mouillage de trois heures chacun, par semaine, dans une solution d’hypochlorite de sodium (eau de javel) à 6% (Phase I), suivi d’une période pouvant atteindre 90 jours de conditionnement à 4°C/100 % HR (Phase II). Les granulats ayant un potentiel d'oxydation ont présenté une expansion de 0,10 % au cours de la Phase I, tandis que la formation potentielle de thaumasite est détectée par le regain rapide de l'expansion suivi par la destruction des échantillons durant la Phase II. Un test de consommation d'oxygène a également été modifié à partir d’un test de Drainage Minier Acide, afin d'évaluer quantitativement le potentiel d'oxydation des sulfures de fer incorporés dans les granulats à béton. Cette technique mesure le taux de consommation d'oxygène dans la partie supérieure d'un cylindre fermé contenant une couche de matériau compacté afin de déterminer son potentiel d'oxydation. Des paramètres optimisés pour évaluer le potentiel d'oxydation des granulats comprennent une taille de particule inférieure à 150 μm, saturation à 40 %, un rapport de 10 cm d'épaisseur de granulat par 10 cm de dégagement et trois heures d’essai à 22ᵒC. Les résultats obtenus montrent que le test est capable de discriminer les granulats contenant des sulfures de fer des granulats de contrôle (sans sulfures de fer) avec un seuil limite fixé à 5% d'oxygène consommé. Finalement, un protocole d'évaluation capable d’estimer les effets néfastes potentiels des granulats à béton incorporant des sulfures de fer a été proposé. Le protocole est divisé en 3 grandes phases: (1) mesure de la teneur en soufre total, (2) évaluation de la consommation d'oxygène, et (3) un test accéléré d’expansion sur barres de mortier. Des limites provisoires sont proposées pour chaque phase du protocole, qui doivent être encore validées par la mise à l’essai d'un plus large éventail de granulats.In the Trois-Rivières area (Quebec, Canada), more than 1 000 houses and commercial buildings are showing serious concrete deterioration problems. The deterioration problems are related to the oxidation of sulfide-bearing aggregates used for concrete manufacturing. This PhD project aims to better understand the mechanisms responsible for the deterioration of concrete incorporating sulfide-bearing aggregates in order to develop a methodology to efficiently evaluate the potential reactivity of such types of aggregates. A detailed petrographic examination of core samples extracted from concrete house foundations showing various degrees of severity was carried out. The problematic aggregate was identified as an hypersthene’s gabbro incorporating various proportions (according to different locations in the two originating quarries) of pyrrhotite, pyrite, chalcopyrite and pentlandite. Secondary reaction products observed in degraded core samples include “rust” mineral forms, gypsum, ettringite and thaumasite. For those observations, it was concluded that, in presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulfuric acid that provokes a sulfate attack in concrete. First, the reliability of the chemical approach proposed in the European Standards NF EN 12 620, which consists in the measurement of the total sulfur content (ST, % by mass) in the aggregate to detect the presence (or not) of iron sulfide minerals, was critically evaluated. About 50% (21/43) of the aggregate materials tested, representing a variety of rock types / lithologies, showed a ST > 0.10%, showing that a significant proportion of rock types does contain a noticeable amount of sulfide, which for most of them, are likely to be innocuous in concrete. Such rock types / aggregates would however require further testing to identify the potential presence of pyrrhotite considering the ST limit of 0.10% proposed in European standards. Based on extensive literature reviews and laboratory investigations, a two-phase accelerated mortar bar expansion test was then developed to reproduce, in the laboratory, the deterioration mechanisms observed on site. The test consists in 90 days of storage at 80°C/80% RH, with 2 three-hour wetting cycles per week in a 6% sodium hypochlorite (bleach) solution (Phase I) followed by up to 90 days of storage at 4°C/100% RH (Phase II). Aggregates with oxidation potential presented an expansion over 0.10% during Phase 1, while thaumasite formation potential is detected by rapid regain of expansion followed by destruction of the samples during Phase II. Also, an oxygen consumption test was modified from research carried out in the context of acid rock drainage, to quantitatively assess the sulfide oxidation potential of concrete aggregates. The technique measures the oxygen consumption rate at the top of a closed cylinder containing a layer of compacted material to determine its oxidation potential. Optimized testing parameters include an aggregate particle size inferior to 150 μm at 40% saturation, a ratio of 10 cm of aggregate material thickness for 10 cm headspace and 3 hours testing at 22ᵒC. The results thus obtained showed that the test is able to discriminate the aggregates containing iron sulfide minerals from the control aggregates with a threshold limit fixed at 5% oxygen consumed. Finally, an assessment protocol was proposed to evaluate the potential deleterious effects of iron sulfide bearing aggregates when used in concrete. The protocol is divided into 3 major phases: (1) total sulfur content measurement, (2) oxygen consumption evaluation, and (3) an accelerated mortar bar expansion test. Tentative limits are proposed for each phase of the protocol, which still need to be validated through the testing of a wider range of aggregates.
46
You, Liang. "Copper Sulfide Solid-State Electrolytic Memory Devices". Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1160337918.
Testo completo
47
PIAO, HAISHAN. "STABILIZATION OF MERCURY-CONTAINING WASTES USING SULFIDE". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1059751247.
Testo completo
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Kothurkar, Nikhil K. "Solid state, transparent, cadmium sulfide-polymer nanocomposites". [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0006485.
Testo completo
49
Junkermeier, Chad Everett. "Simulation and Analysis of Cadmium Sulfide Nanoparticles". Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2704.pdf.
Testo completo
50
Hurse, Timothy John. "Sulfide removal from wastewater by phototrophic microorganisms /". [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16390.pdf.
Testo completo