Spelling suggestions: "subject:"8ulfate"" "subject:"bsulfate""
211 |
Chemical synthesis of heparan sulfate oligosaccharides for use in single molecule fluorescence analysisDalton, Charlotte January 2016 (has links)
Heparan sulfate (HS) is a cell-surface sulfated polysaccharide that binds to multiple proteins and has been implicated in cancer, viral infection and Alzheimer's disease. Due to the heterogeneity of HS, the structural requirements for protein binding are ill- defined. Chemical synthesis of structurally-defined HS oligosaccharides, which are tunable in terms of length, order of monosaccharides and sulfation pattern, is required for the investigation of HS-protein binding. Single molecule methods have been utilised in biophysics to study dynamic processes and can allow observation of rare events which would be 'averaged out' in ensemble measurements. Access to fluorescently labelled HS oligosaccharides should allow investigation of interactions with proteins at the single molecule level using methods such as single molecule FRET, providing a method complementary to NMR studies (ensemble) and X-ray crystallography (non-dynamic).This thesis presents the development of a method for the fluorescent labelling of a chemically synthesised HS disaccharide utilising a reducing-end amine tag. Analysis of the fluorescence properties of the labelled disaccharide at ensemble and single molecule level indicated no perturbation of the fluorophore when attached to the sugar. Fluorescence correlation spectroscopy measurements of the fluorescent HS disaccharide with the protein FGF-1 showed no binding, which is attributed to the low concentration (1 nM) of disaccharide required in the experiment. Additional work is presented in this thesis on the development of a method for atom-specific 13C labelling of HS oligosaccharides, which has been initiated by synthesis of a 13C labelled L-iduronate monosaccharide and a 13C labelled disaccharide. New strategies for the synthesis of HS oligosaccharides based on orthogonal thioglycoside-based glycosylations employing S-benzoxazolyl and S-thiazolyl donors have been investigated. Development of a chemoselective glycosylation strategy for HS oligosaccharide synthesis utilising a 'super-disarmed' [2.2.2] L-iduronic lactone is presented.
|
212 |
Formação da eflorescência em cerâmica vermelha : fatores de influência no transporte dos íons SO4 e CaFerreira, Cristiano Correa January 2009 (has links)
Neste trabalho, investigou-se a migração dos íons SO4 -2 e Ca+2 em uma cerâmica vermelha aditivada com CaSO4.2H2O simulando o processo de eflorescência. Para tanto, uma massa cerâmica com tendência não patológica, à base de uma argila da região de Gravataí-RS, foi formulada com 0, 4, 8, 12 e 16% em peso de CaSO4.2H2O. No processamento cerâmico, utilizou-se a conformação por extrusão a vácuo e queima em forno elétrico tipo mufla a diferentes temperaturas (800, 850, 900 e 950ºC) com patamar de doze horas. Os corpos cerâmicos obtidos em dimensões de 70x27x9mm3 foram caracterizados quanto às propriedades físicas (absorção de água e porosidade aparente). Para avaliar a mobilidade dos íons SO4 -2 e Ca+2, foram realizados ensaios de eflorescência segundo a norma ASTMC67/2003, análise da distribuição de tamanho de poros nos corpos cerâmicos investigados, ensaios de solubilização durante os períodos de uma hora com os corpos cerâmicos imersos em água a 90°C e imersão dos corpos cerâmicos por sete, quatorze e vinte e oito dias consecutivos em temperatura ambiente. Também foram realizados testes de condutividade elétrica nos solubilizados dos corpos cerâmicos durante os períodos de uma hora e de sete dias de ensaio e avaliou-se a potencialidade desses íons na formação do fenômeno em função das variáveis temperatura e pH. Para a quantificação da eflorescência, foi desenvolvida uma nova metodologia por análise de imagem utilizando o software gráfico Image Tools versão 3.0. Os resultados obtidos permitiram identificar que a nova metodologia baseada em análise de imagens mostrou-se bastante eficiente para quantificar a eflorescência em corpos cerâmicos, diminuindo a subjetividade da avaliação visual. Constatou-se que o íon cálcio possui maior mobilidade do que o íon sulfato após sete dias de repouso. Para maiores tempos de repouso, quatorze e vinte e oito dias, a diferença entre as concentrações por solubilização dos íons Ca+2 e SO4 -2 diminui significativamente. Também foi possível identificar uma tendência (com poucas exceções): os valores da concentração do íon Ca+2 são maiores do que os da concentração de SO4 -2 para um mesmo volume total e diâmetro médio de poros e mesma quantidade de sulfato de cálcio na formulação. Da mesma forma, quando a concentração por solubilização dos íons Ca+2 e SO4 -2 é relacionada à absorção de água dos corpos cerâmicos investigados, e comparando-os com os resultados dos ensaios de eflorescência por imagem, constata-se uma similaridade entre os resultados da eflorescência e da concentração do íon Ca+2 após sete dias de repouso. Já para o íon SO4 -2, os resultados de eflorescência assemelham-se aos de quatorze dias de repouso. A formação da eflorescência está intimamente ligada à porosidade e aos índices de concentração de sal e absorção de água dos corpos cerâmicos. Ao mesmo tempo, os ensaios de solubilização investigados mostraram-se ótimos instrumentos para análise do fenômeno, permitindo, de forma bastante confiável, que se disponha de dados sobre a formação da eflorescência em corpos cerâmicos. / In this work, the displacement of SO4 -2 and Ca+2 ions in red ceramic was investigated simulating the efflorescence process. Ceramic bodies were molded (70x27x9mm3) by vacuum extrusion formulated with different contents of CaSO4.2H2O (0, 2, 4, 8, 16% in weight) and burnt at different temperatures (800, 850, 900, 950°C) for 12 hours. Microstructure was evaluated for water absorption, apparent porosity, and pore size distribution. Efflorescence was evaluated according to the ASTMC67/2003 norm. Tests of SO4 -2 and Ca+2 ion solubilizations after periods of 1 hour with the ceramic bodies immerged in hot water and periods of 7, 14 and 28 consecutive days with the ceramic bodies in cold water were carried out. Tests were also made of electrical conductivity in solubilized from ceramic bodies during one hour and during seven days and evaluated the potential of these ions to formation of efflorescence regarding the variables temperature and pH. In the efflorescence quantification, an image analysis methodology was developed using the graphic software Image Tools 3.0. Results allowed establishing a relationship between the efflorescence of the investigated ions, physical properties (water absorption and apparent porosity), pore size distribution, and solubilization. The new methodology based on the analysis of images is sufficiently efficient to quantify efflorescence in ceramic bodies, reducing the subjectivity of the visual evaluation. Calcium ion has larger mobility than sulfate ion after 7 days of rest. For longer periods of rest (14 and 28 days), the difference between the concentrations by solubilization of Ca+2 and SO4 -2 ions significantly reduces. It was also possible to identify the tendency (with few exceptions) that the concentration values of the Ca+2 ion are bigger than the concentration values of SO4 -2 for the same total volume and average diameter of pores as well as the same amount of calcium sulfate in the formularization. Likewise, when the concentration for the solubilization of the Ca+2 and SO4 -2 ions is related to water absorption of the ceramic bodies investigated as well as when we compare them with the results of the assays of efflorescence for image, a similarity between the results of the efflorescence and the concentration of the Ca+2 ion after 7 days of rest is observed. For the SO4 -2 ion, the efflorescence results are similar to 14 days of rest. The formation of efflorescence is closely linked to the porosity and to the indices of concentration of salt and water absorption contained in the products at the same time. The investigated assays of solubilization showed to be excellent instruments for analysis of the phenomenon allowing, sufficiently trustworthy, the obtaining of data on the formation of efflorescence in ceramic bodies.
|
213 |
Perfil fermentativo da linhagem CAT-1 em mosto contendo alta concentração de açúcar em sistema descontínuo alimentado / CAT-1 yeast strain fermentation profile in medium with very high gravity in fed batch systemFrancischetti, Graziela 09 August 2017 (has links)
O etanol é o combustível que mais se destaca como alternativa à gasolina no setor do transporte. No entanto, a melhoria da eficiência da fermentação, aprimorando o processo de conversão de biomassa em etanol combustível e reduzindo o custo de produção são desafios ainda pertinentes. Neste cenário, as fermentações com alta concentração de açúcar ou VHG (very high gravity) estão sendo cada vez mais estudadas. A adição de compostos como fonte de nitrogênio pode gerar benefícios para a produção de etanol, entretanto, a maioria dos estudos com suplementação de fontes nitrogenadas é realizada em sistema descontínuo simples e em escala laboratorial, embora os processos fermentativos industriais sejam conduzidos em sistema descontínuo alimentado. Neste contexto, este trabalho visou avaliar o perfil fermentativo da linhagem CAT-1 em mosto contendo alta concentração de açúcar fermentescível e suplementado com as fontes nitrogenadas peptona e sulfato de amônio, nas concentrações 5 e 10 g/L, em sistema de descontínuo simples e descontínuo alimentado com reciclo de células, utilizando diferentes escalas produtivas. Nos experimentos em sistema descontínuo simples, os tratamentos controle e peptona (5 g/L) apresentaram uma melhor produção de etanol, maior rendimento e produtividade em comparação com os demais tratamentos. Nos experimentos em sistema descontínuo alimentado não houve diferença significativa entre os tratamentos controle e peptona 5 e 10g/L, porém, o tratamento com sulfato de amônio (10 g/L) apresentou parâmetros fermentativos de produção de etanol e produtividade superiores ao tratamento controle, o oposto do descontínuo simples. Os resultados mostraram que quando as células de levedura foram submetidas a concentrações crescentes de açúcar, como é o caso do sistema descontínuo alimentado, ocorre uma adaptação das mesmas, proporcionando melhores resultados, com uma redução no tempo de fermentação para 16h. Além disso, a alta concentração de etanol no meio fermentativo causa um efeito prejudicial às células, já que nos tratamentos onde houve teores mais elevados de etanol ocorreu menor viabilidade e maior quantidade de açúcar residual. / Ethanol is the fuel that stands out as an alternative to gasoline in the transportation sector. However, improving the efficiency of fermentation, improving the process of converting biomass to fuel ethanol and reducing the cost of production are still relevant challenges. In this scenario, fermentations with high sugar concentration or very high gravity (VHG) are being studied more and more. The addition of compounds as a source of nitrogen can generate benefits for ethanol production, however, most of the studies with nitrogen supplementation are carried out in a simple discontinuous system and in laboratory scale, although the industrial fermentation processes are conducted in a fed batch system . In this context, the objective of this work was to evaluate the fermentation profile of the CAT-1 strain in must containing high fermentable sugar concentration and supplemented with nitrogen peptone and ammonium sulfate at 5 and 10 g / L in a simple discontinuous system and fed batch system, fed with recycle of cells, using different productive scales. In the simple discontinuous system experiments, the control and peptone treatments (5 g / L) presented better ethanol production, higher yield and productivity in comparison to the other treatments. However, the treatment with ammonium sulfate (10 g / L) showed fermentative parameters of ethanol production and productivity higher than the control treatment, the opposite of simple discontinuity. The results showed that when the yeast cells were submitted to increasing concentrations of sugar, as is the case of the fed batch system, an adaptation occurs, providing better results, with a reduction in the fermentation time to 16h. In addition, the high concentration of ethanol in the fermentation medium causes a detrimental effect on the cells, since in the treatments with higher levels of ethanol; less viability and more residual sugar were observed.
|
214 |
Efeito da incorporação de soluções desinfetantes no tempo de presa, reprodução de detalhes e estabilidade dimensional de um gesso tipo IV /Lucas, Matheus Guilherme. January 2004 (has links)
Orientador: João Neudenir Arioli Filho / Resumo: A interação física direta entre o consultório odontológico e o laboratório de prótese representa um enorme obstáculo para um controle eficaz de infecção cruzada entre estes ambientes. Com isso, neste trabalho foi proposto analisar a influência das técnicas alternativas de desinfecção no tempo de presa, estabilidade dimensional linear e reprodução de detalhes de modelos em gesso. Para isso, foram confeccionadas amostras em gessos pedra tipo IV (Fugi Rock - GC América) com soluções desinfetantes (hipoclorito de sódio 1,0%, glutaraldeído 2% e clorexidina 2%) incorporadas à sua composição em duas concentrações (50 e 100%). Com base nos resultados obtidos, concluiu-se que a adição das soluções desinfetantes alterou de maneira estatisticamente significante o tempo de presa, porém a alteração encontrada no grupo com adição de hipoclorito de sódio demonstrou-se fora dos padrões exigidos pela I.S.O. Com relação à reprodução de detalhes e estabilidade dimensional, a adição de glutaraldeído e clorexidina comportou-se de maneira semelhante ao grupo controle, já o grupo com hipoclorito de sódio provou alterar negativamente tais características. / Abstract: The direct physical interaction between the dental Office and the prosthetics lab represents an enormous obstacle for the efficient control of the cross infection between those two places. The aim of this paper was to analyze the influence of the alternative disinfection techniques during the cast die stone setting time, the linear dimension stability and the reproduction details on cast model. For that samples of die stone type IV Fugi Rock - GC America) with disinfection solutions (Sodium Hypochlorite 1%, Glutaraldeído 2,0% and clorhexidine 2%) incorporated into its compositions in two concentrations (50 and 100%). It was concluded, with base on the results obtained, that the addition of glutaraldeído and clorhexidine did not promote significant alterations on the evaluated properties, however, the addition of sodium hypochlorite in both dilutions significantly altered negatively all the evaluated properties. It was concluded that the incorporation of glutar and clorhexidine, on the evaluated concentrations, can be used on the disinfection of cast model, not promoting alterations on the setting time, dimensional linear alteration and detail reproduction. / Mestre
|
215 |
Chamber studies of the heterogeneous reaction of sulfur dioxide with particulate hematiteVanlerberghe, Jason Francis 01 July 2010 (has links)
The goal of this thesis is to investigate the kinetics and amount of SO2 uptake on hematite, which will act as a representative of mineral dust aerosol. The environmental reaction chamber used here will allow the variation of water vapor pressure to examine the effect of relative humidity (RH) on these parameters. The role of a common atmospheric oxidant, ozone, in the uptake process will also be investigated. The results will be presented with emphasis on the role of hematite in mineral dust aerosols as a sink of SO2, and the possible acidification of hematite particles through heterogeneous reaction pathways.
|
216 |
Heparan Sulfate, A New Target for Platinum in Metastatic TNBCKatner, Samantha J 01 January 2018 (has links)
Abstract
Heparan Sulfate, A New Target for Platinum in Metastatic TNBC
Author: Samantha J. Katner, Ph.D.
A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy
Virginia Commonwealth University, 2018
Advisor: Dr. Nicholas Farrell, Professor, Chemistry Department
Heparan sulfate proteoglycans (HSPGs), composed of the linear polysaccharide heparan sulfate (HS) conjugated to a protein core, are located on the cell surface and extracellular matrix. The HS chains display varying degrees of sulfation, which constitutes the molecular recognition motif for many HS-protein interactions. HSPGs, associated growth factors, and heparanase promote tumor progression by facilitating invasion, angiogenesis, and metastasis.1 Sulfate clusters on the glycan backbone also mediate the interaction of polynuclear platinum complexes (PPCs) with HSPG through a “sulfate clamp.” Such PPC-HS interactions can be conceptualized as “polyarginine” mimics. Strong HS-PPC binding protects the oligosaccharide against sulfate loss through metalloshielding.2 The biological consequences of metalloshielding will in principle affect HS interactions with relevant enzymes and proteins such as heparanase and growth factors, similar in concept to the inhibition of DNA-protein binding through modification of DNA structure and conformation. The end-point of functional modulation of HS interactions is inhibition of angiogenesis and metastasis.
PPCs are dual-function agents through their interactions with both nucleic acids and HS. The novel Pt-HS interactions open up new areas of metalloglycomics and potential anti-angiogenic activity. Here, we report PPC interactions with HS-like models: Fondaparinux (FPX)3 and heparin4. We demonstrate TriplatinNC high affinity to heparin in biophysical studies and compare HS interactions with DNA and HS using competition assays.3,4 these approaches may be extended to a range of metal-ammine compounds.4
The biological consequences of PPC-HS interactions include modulation of heparanase cleavage of FPX,3 growth factor binding to HS, and growth factor-induced migration and signaling in breast cancer and endothelial cells, as potential anti-metastatic and anti-angiogenic effects in vivo. We report proof-of-principle of strong in vivo anti-metastatic activity of PPCs in triple negative breast cancer (TNBC) models.5–7 Already, PPC-HS interactions have major biological consequences in the aggressive metastatic TNBC mouse models. Impressively, PPCs reduce overall tumor metastases with emphasis in lung, bone, and liver locations in both immunocompetent and immunosuppressive mouse models. PPCs demonstrated permeability through the blood brain barrier (BBB) implying further applications for PPCs. PPCs represent a novel class of intrinsically dual-function agents combining platinum cytotoxicity through DNA targeting with anti-angiogenic effects through glycan targeting. Together, these results suggest that strong PPC-HS interactions have a significant role in the inhibition of breast cancer metastases, particularly in metastatic TNBC patients.
1. Peterson, E. J. et al. Antiangiogenic platinum through glycan targeting. Chem. Sci. 8, 241–252 (2017).
2. Mangrum, J. B. et al. A new approach to glycan targeting: enzyme inhibition by oligosaccharide metalloshielding. Chem. Commun. (Camb). 50, 4056–8 (2014).
3. Gorle, A. K. et al. Substitution-Inert Polynuclear Platinum Complexes as Metalloshielding Agents for Heparan Sulfate. Chem. Eur. J (2018). doi:10.1002/chem.201706030
4. Katner, S. J., Johnson, W. E., Peterson, E. J., Page, P. & Farrell, N. P. Comparison of Metal–Ammine Compounds Binding to DNA and Heparin. Glycans as Ligands in Bioinorganic Chemistry. Inorg. Chem. acs.inorgchem.7b03043 (2018). doi:10.1021/acs.inorgchem.7b03043
5. Katsuta, E., Peterson, E. J., Katner, S. J., Farrell, N. P. & Takabe, K. Triplatin preferably suppress lung metastasis of breast cancer, and peritoneal carcinomatosis of colon and pancreatic cancer. Proc. AACR Washingt. D.C. Abstract #5117 (2017).
6. Katner, S. J. et al. Heparan sulfate , a new target for platinum in metastatic TNBC. Proc. AACR Chicago, Abstract #3941 (2018).
7. Katner, S. J. et al. Anti-metastatic platinum through glycan targeting in breast cancer. Proc. AACR Washingt. D.C. Abstract #17 (2017).
8. Silva, H. et al. Heparan sulfate proteoglycan-mediated entry pathway for charged tri-platinum compounds. Differential cellular accumulation mechanisms for platinum. Mol. Pharmacol. 9, 1795–1802 (2012).
9. Peterson, E. J. et al. Nucleolar targeting by platinum: P53-independent apoptosis follows rRNA inhibition, cell-cycle arrest, and DNA compaction. Mol. Pharm. 12, 287–297 (2015).
|
217 |
Metalloglycomics: Investigating the Interactions of Metal Complexes with Heparan MimeticsJohnson, Wyatt 01 January 2018 (has links)
Proteoglycans containing Heparan Sulfate (HS), a sulfated glycosaminoglycan (GAG), play a major role in the cell signaling process, interacting with many different proteins. HS is over expressed on the surface of many cancer cells. Enzymatic cleavage of HS-GAGs by heparanase causes release of angiogenic growth factors leading to tumor cell migration. Heparanase is also over-expressed in tumors with significant correlation between metastatic potential and heparanase activity. Proteoglycans and their associated enzymes are thus significant drug targets of high biological relevance.
A functional consequence of strong PPC-HS binding has been shown in proof-of-concept studies confirming inhibition of the model pentasaccharide, Fondaparinux, by bacterial Heparinase. Such metalloshielding by PPCs may also protect HS from enzymatic cleavage by the mammalian heparanase; preventing growth factors from binding to HS and/or preventing release of bound growth factors and thus inhibiting the metastatic response in the cancer cells. HS-GAGs are also receptors for cellular accumulation of cationic Polynuclear Platinum Complexes (PPCs) through high-affinity binding to the highly anionic HS. PPCs competitively inhibit uptake of TAMRA-R9, a fluorescent nona-arginine derivative, in CHO cells.
The previously reported series of Pt(II) complexes were investigated as DNA binders, initiating the apoptotic cascade. The result of PPC-DNA binding produces long range inter and intra-strand cross-links, that produce structural and conformational changes. Hydrogen bonding between phosphate oxygens and square planar Pt(II) nitrogen results in bidentate complexes by either backbone tracking or groove spanning of DNA. This complex forms a clamp like structure, called a phosphate clamp, similar to that of the arginine fork. Understanding this clamp allows us to investigate the structurally similar sulfate binding between metal complexes and target HSPG. HSPGs may allow significant research into both a novel cellular internalization of principal metals and “metalloshielding” of heparin by these compounds.
Previous studies have shown that a wide range of metal ions have high affinity to heparin. The trend of metal/heparin affinity is believed to be dependent on parameters consisting of the metal’s overall size, spatial orientation of the ligands attached to each metal, the net charge and oxidation state of these metals, and number of binding sites. Studies have shown relative affinities of sulfate and carboxylate groups for the metal ions. These metal cations play an important role in the affinity, specificity, and stability of many protein/heparin interactions. The study of simple coordination compounds, like Pt, Mn, V, Ru and Co, will allow preliminary results which will extend into the PPCs mode of binding.
This thesis focuses on the concept of metalloglycomics and reviews the interactions of various metal complexes with heparin. The covalent and non-covalent interactions of metal complexes with heparin resulting in strong bonding are explained through spectroscopy and calorimetry. The cleavage inhibition of heparanase by metal complexes is also described. Sulfate cluster anchoring shields the sulfates from loss as seen in mass spectrometry. The study of metalloglycomics offers potential understanding into the relevance of metal-heparin interactions and possibilities into the development of new compounds as therapeutic agents.
|
218 |
Thermodynamic properties of concentrated zinc bearing solutionsVielma, T. (Tuomas) 10 September 2019 (has links)
Abstract
Zinc is a common metal, and has a central role in the production of galvanised bulk products, battery applications and fertilisers. Its production relies mainly on the leaching of zinc minerals with sulfuric acid, followed by purification and electrowinning. In this thesis an internally consistent thermodynamic model for the industrially important ZnSO₄-H₂SO₄-H₂O system was developed. Model parameters were optimised using available literature data and new experimental freezing point and density data determined in this work. With Gibbs energy minimisation algorithms embedded in commercial software, such as ChemSheet and FactSage, the developed model can be used to calculate easily phase equilibria and thermodynamic properties of aqueous zinc sulfate solutions and solid zinc sulfate phases, including activity coefficients, enthalpy changes, heat capacities, densities and solubilities, in a wide range of temperature, pressure and sulfuric acid concentrations. Solution non-ideality was treated with the original Pitzer model with electrostatic mixing terms included.
Applicability of thermodynamic approach and the developed model was demonstrated by two separate case studies on the hydrometallurgical zinc process. Precipitation of amorphous silica during hot acid leach was studied experimentally. Its solubility in the process solution was also successfully predicted using the thermodynamic approach. To study crystallisation of gypsum during the gypsum precipitation stage, the model was expanded by addition of the Ca²⁺ ion. The model calculations showed good agreement with the experienced Ca²⁺ levels.
The results of this thesis have found immediate use in understanding the various stages of the electrolytic zinc process. The obtained results also form a basis on which new, more advanced tools for managing and studying the process can be developed. / Tiivistelmä
Sinkki on yleinen metalli, ja sillä on keskeinen rooli sinkittyjen terästuotteiden, paristojen ja jopa lannoitteiden valmistuksessa. Sen tuotanto perustuu sinkkipitoisten mineraalien rikkihappoliuotukseen, muodostuneen prossessiliuoksen puhdistukseen ja lopulta metallisen sinkin elektrolyysitalteenottoon. Tässä työssä kehitettiin termodynaaminen malli teollisesti tärkeälle ZnSO₄-H₂SO₄-H₂O -systeemille. Malliparametrit määritettiin kirjallisuudessa esitetyistä tuloksista ja tässä työssä tehdyistä uusista jäätymispiste- ja tiheysmittauksista. Käyttämällä kaupallisia Gibbsin energian minimointialgoritmiin perustuvia ohjelmistoja, kuten ChemSheet tai FactSage, tässä työssä kehitetyllä mallilla voidaan helposti kuvata sinkkisulfaattipitoisten vesiliuosten faasitasapainoja ja laskea systeemin termodynaamisia ominaisuuksia. Malliin sisällytettyihin ominaisuuksiin kuuluvat systeemin komponenttien aktiivisuudet, entalpiamuutokset, lämpökapasiteetit sekä tiheydet laajalla lämpötila-, paine- ja rikkihapon pitoisuusalueella. Liuoksen epäideaalisuutta kuvattiin Pitzerin ioniaktiivisuusmallilla.
Työssä sinkkisulfaattiliuoksille kehitettyä mallia testattiin kahdessa sinkintuotannon kannalta keskeisessä tapaustutkimuksessa. Amorfisen piidioksidin saostumista vahvahappoliuotuksen aikana tutkittiin kokeellisesti ja laskennallisesti. Amorfisen piidioksidin liukoisuus prosessiliuokseen ennustettiin onnistuneesti. Kipsinpoistoprosessin tutkimusta varten mallia laajennettiin lisäämällä siihen Ca²⁺-ioni. Mallilla laskettiin kipsin liukoisuus prosessiliuokseen. Saadut tulokset vastasivat hyvin käytännössä havaittuja arvoja.
Tutkimuksen tuloksia on suoraan hyödynnetty sinkintuotantoprosessin ymmärtämisessä. Ne myös mahdollistavat jatkossa edistyneempien työkalujen kehittämisen niin prosessin hallintaan kuin tutkimukseenkin.
|
219 |
Diagenesis and Water Chemistry of the Woodbine Group in the East Texas BasinWuerch, Helmuth Victor 01 May 1986 (has links)
Petrographic and SEM study of flu vial-deltaic sections of the Woodbine Group in the East Texas Basin indicates that authigenic mineral suites are controlled, in part, by the presence of organic-rich matrix.
During early, precompaction diagenesis, organic matter supplied the metabolic fuel required by sulfate-reducing bacteria to reduce sulfate in depositional waters ultimately to pyrite. With burial the sulfate supply was ultimately exhausted, and bicarbonate activity thereafter controlled the precipitation of siderite and Fe-calcite.
Matrix material supplied the components and reaction sites for the most import ant porosity-occluding reaction: kaolinite --> Fe,M g chlorite. Matrix physically inhibited the growth of quartz overgrowths, yet, through compaction and as a product of the above reaction, provided a supply of silica for quartz cementation. Dissolution of salt dome cap rock has played a minor role in the cementation of the Woodbine in the East Texas Basin. Pore-filling calcite, barite, and pyrite were observed in the Woodbine where the Woodbine is in direct hydraulic communication with salt dome cap rock.
In the deep, central portion of the basin Na-Cl brine resulting from salt-dome dissolution is evolving toward a Na-Ca(Mg)-Cl brine. The evolution of the brine chemistry may be the result of cation exchange on clay minerals, albitization of plagioclase feldspars, or the dissolution of magnesium - and calcium- chloride-rich phases. The present study could not confirm any of these reactions.
WATEQF was used to calculate mineral-saturation states in Woodbine waters. Program output appears to represent accurately in situ individual mineral-saturation states at measured pH, as confirmed by petrographic and SEM identification of authigenic minerals. Relative stability between mineral pairs can be tested with thermodynamically-derived activity diagrams for the mineral pairs.
|
220 |
Etude de l'aérosol atmosphérique en Europe : observations et modélisation en sites d'altitudeDombrowski-Etchevers, Ingrid 15 December 2008 (has links) (PDF)
L'aérosol atmosphérique a un impact à la fois sur l'environnement via les effets directs et indirects sur le rayonnement et sur l'homme en raison de sa toxicité. Pourtant, ses caractéristiques physiques et chimiques sont encore mal connues. Ce travail avait un double but. D'une part, effectuer des mesures de la fraction soluble (minérale et organique) de l'aérosol dans une carotte de glace du Mont-Blanc et sur des filtres de six stations européennes géographiquement et climatologiquement différentes du projet CARBOSOL. Ces mesures ont confirmé l'importance de la convection pour le transport des aérosols, notamment le sulfate, des basses couches vers la troposphère libre. En conséquence, dans l'autre partie de ce travail, on s'est d'abord attaché à bien évaluer la capacité de transport des aérosols par le modèle de chimie-transport MOCAGE via une simulation du 210Pb pour les années 2002 à 2004. Les résultats ont été comparés aux mesures des six stations de CARBOSOL. Enfin, une chimie du soufre a été intégrée dans MOCAGE et évaluée pour l'été 2003.
|
Page generated in 0.0455 seconds