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Gray, C. J. "Lithogeochemical aureoles to Irish mineralisation." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381482.
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Brookshaw, Diana Roumenova. "Mineralisation and biomineralisation of radionuclides." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/mineralisation-and-biomineralisation-of-radionuclides(6c4c0f0e-96f6-4960-a1aa-9c0aa6eaa126).html.
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Management of contamination from industrial activities and wastes from nuclear power generation and weapons development are arguably amongst the greatest challenges facing humanity currently and into the future. Understanding the mobility of toxic radioactive elements is essential for successful remediation strategies and safe management of our nuclear waste legacy (DEFRA, 2008). Interactions between minerals and radionuclides, such as sorption and precipitation, govern the mobility of the contaminants through the subsurface environment. Microbial metabolic processes (redox cycling or release of metabolites) have the potential to affect drastically these abiotic interactions. Microbially-driven mineralisation processes could provide long-term solid-phase-capture solutions to radionuclide contamination problems and support safety cases for geological disposal of radioactive waste. The recent advancements at the intersection between mineralogy, microbiology and radiochemistry were reviewed with the aid of a cluster analysis (Self-Organising Map). This is a relatively novel method of creating a map of the ‘research landscape’ which provides a visual summary of the reviewed literature and can help to identify areas of promising and active research as well as less researched interdisciplinary areas. It is the first time this tool has been applied to research literature on this interdisciplinary topic, and it highlighted the need to gain further understanding of ternary systems including bacteria, minerals and radionuclides. The analysis showed that phyllosilicates are of interest, but few studies have explored the properties of the Fe(II)/Fe(III)-containing micas biotite and chlorite. The ability of model Fe(III)-reducing microorganisms to reduce Fe(III) in biotite and chlorite was demonstrated in batch model systems. In chlorite, approximately 20% and in biotite ~40% of the bulk Fe(III) was transformed to Fe(II) by this reduction. To our knowledge, this is the first study to show the availability of Fe(III) in biotite for such reduction and the ability of the model organism Shewanella oneidensis MR-1 to conserve energy for growth using Fe(III) in biotite as the sole electron acceptor. The microbial Fe(III) reduction led to a decrease in the sorption of Cs and Sr by chlorite, but had very little effect on sorption to biotite. The data indicate that remediation strategies based on microbial Fe(III) reduction may exacerbate the movement of Cs and Sr through strata where sorption is dominated by phyllosilicates, particularly chlorite. While microbial Fe(III) reduction had only a slight effect on the sorption properties of biotite and chlorite, it drastically altered their redox properties. Previously bioreduced biotite and chlorite readily removed Cr(VI), Tc(VII) and Np(V) by surface-mediated reduction. The minerals were also able to reduce U(VI), but solution chemistry affected this reaction, reflecting the complexity of the biogeochemistry of this actinide. Overall, this work highlights the importance of decoupling microbial and geochemical processes in developing a holistic understanding of radionuclide behaviour in the environment. This body of work forms the thesis is entitled ‘Mineralisation and Biomineralisation of radionuclides’, and was prepared by Diana Roumenova Brookshaw for submission in August 2013 for the degree of Doctor of Philosophy to the University of Manchester.
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Quin, T. G. "Aspects of the mineralisation of iron." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375301.
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Reid, Carol Anne. "Texture analysis of bone mineralisation surfaces." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287800.
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Houston, Dean Alexander. "Regulation of skeletal mineralisation by PHOSPHO1." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29004.
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PHOSPHO1 is a skeletal specific phosphatase whose activity towards the lipid metabolites, phosphocholine (PCho) and phosphoethanolamine (PEth), results in the generation of inorganic phosphate (Pi) within matrix vesicles (MV). PHOSPHO1 activity is essential for the initiation of biomineralisation. The genetic ablation of Phospho1 results in severe hypomineralisation of the skeleton and dentition. Neutral sphingomyelinase 2 (nSMase2, encoded by the Smpd3 gene) catalyses the breakdown of the membrane lipid sphingomyelin to generate ceramide and PCho. Similar hypomineralisation of the skeleton is noted in the Smpd3-/- mouse. This observation led to the hypothesis that nSMase2 and PHOSPHO1 work in tandem for the generation of Pi within MV. Despite knowledge of the phenotype associated with the absence of Phospho1 or Smpd3, little is known about the expression profiles of these genes during the initiation of extracellular matrix (ECM) mineralisation, or the regulation of these genes. This thesis characterised the expression of Phospho1, Smpd3 and other key genes associated with ECM mineralisation in in vitro models of mineralisation under exogenous phosphatase substrate-free conditions. Additionally, building on preliminary work in osteocytes, the regulation of Phospho1 and Smpd3 by parathyroid hormone (PTH) was investigated both in vitro and in vivo. Characterisation of MC3T3 osteoblast-like cell cultures, primary calvarial osteoblast and embryonic metatarsal organ cultures similarly revealed simultaneous and striking increases in the expression of PHOSPHO1 and nSMase2 prior to the onset of ECM mineralisation. In Phospho1-/- cell and organ cultures, ECM mineralisation was markedly diminished, and nSMase2 expression was notably reduced. The parathyroid hormone (PTH) regulation of Phospho1 and Smpd3 in osteocytes was confirmed in MC3T3 osteoblast-like cell cultures. Phospho1 and Smpd3 mRNA expression was strongly and rapidly (within 15 minutes) inhibited by PTH. Experiments with cycloheximide revealed that this was a direct effect not requiring protein synthesis. Further experimentation utilising the adenylyl cylase agonist, Forskolin and the PKA inhibitor, PKI (5-24), identified the cAMP-PKA signalling pathway as the mediator of the effects of PTH on Phospho1 and Smpd3 expression. In contrast, however, primary calvarial osteoblasts, human subchondral bone osteoblasts and murine embryonic metatarsal cultures all displayed an upregulation of Phospho1 expression in response to a 24 h exposure to PTH. Although informative, these findings highlighted the need to investigate the PTH regulation of Phospho1 in vivo. The administration of PTH (80 μg/kg) enhanced the expression of Phospho1 and Smpd3 within 6 h and after 14 and 28-day intermittent exposure in the distal femur of male wild-type mice. The expression of the transcription factors, Runx2 and Trps1, which have been implicated in the regulation Phospho1 were similarly upregulated by these PTH exposures. I hypothesised that the upregulation of Phospho1 could provide a novel mechanism explaining the osteoanabolic effects of intermittent PTH (iPTH). Bone microarchitecture in response to iPTH was assessed in the tibiae of WT and Phospho1-/- mice by micro computed tomography. The absence of Phospho1 limited the anabolic effects of PTH in cortical bone but not in the metaphyseal trabecular bone. The work described within this thesis provides further evidence of the cooperative functions of nSMase2 and PHOSPHO1 in the initiation of skeletal mineralisation. The potent regulation of these enzymes in vivo by PTH offers an additional explanation of the anabolic effects of iPTH and forms part of an emerging body of evidence seeking to understand the regulation of these enzymes.
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Staines, Katherine Ann. "Role of MEPE in chondrocyte matrix mineralisation." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/8157.
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Matrix Extracellular Phosphoglycoprotein (MEPE) is a member of a family of proteins called small integrin-binding ligand, N-linked glycoproteins (SIBLINGs) which play key roles in biomineralisation. Altered MEPE expression is associated with several phosphate and bone-mineral metabolic disorders such as oncogenic osteomalacia and hypophosphatemic rickets. Despite this, it remains undetermined what impact MEPE has on the growth plate; the cartilage anlagen from which endochondral ossification, the process responsible for linear bone growth, occurs. The work of this thesis has characterised the ATDC5 cell line and the metatarsal organ culture as useful in vitro models of endochondral ossification. These will prove vital in the pursuit of underpinning the molecular mechanisms involved in endochondral bone growth. These models form the basis of the further studies in this thesis examining the role of MEPE within this highly orchestrated process. Before such role can be defined, this thesis details the spatial and temporal localisation patterns of MEPE in 10-day- and 4-week-old murine growth plates. More specifically, MEPE protein and mRNA were preferentially expressed by the hypertrophic chondrocytes as shown by immunohistochemistry and in situ hybridisation respectively. Microdissection of the murine growth plate confirmed this. Localisation of the cleavage product of MEPE, a 2.2kDa acidic serine- and aspirate-rich motif (ASARM) peptide, followed a similar pattern of expression. The localisation of MEPE to sites of mineralisation serves to strengthen its potential role in chondrocyte matrix mineralisation. This thesis identified this role in both mineralising ATDC5 cells and the metatarsal organ culture. The ASARM peptide was found to be the functional component of MEPE and this function was dependent upon its post-translational phosphorylation. Phosphorylated (p)ASARM peptides significantly inhibited chondrocyte matrix mineralisation without altering the proliferation or differentiation of the chondrocyte cells, or their ability to produce an extracellular matrix. mRNA analysis by qPCR indicted a feedback system by which the pASARM peptide functions to allow the release of further ASARM peptides. Moreover, the pASARM peptide inhibited mRNA expression of markers of vascular angiogenesis highlighting a novel mechanism by which they may inhibit chondrocyte matrix mineralisation. This thesis also determines the regulatory cross-talk between the chondrocytes of the murine growth plate, with the most abundant bone cell type, the osteocyte. This cross-talk inhibits chondrocyte matrix mineralisation and is attributed to sclerostin, an osteocyte-specific secretory protein. Furthermore, it is shown that sclerostin acts through the MEPE-ASARM axis to regulate chondrocyte matrix mineralisation and thus endochondral ossification. The work described herein has characterised and validated in vitro models of growth plate chondrocyte matrix mineralisation and has used these to identify the role of MEPE within chondrocyte matrix mineralisation.
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Nimfopoulos, M. K. "Manganese mineralisation near Kato Nevrokopi, Drama, Greece." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233390.
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The manganese mineralization near Kato Nevrokopi, Drama, in the Falakron mountains, is hosted by the Precambrian to Early Paleozoic Upper Marble. The marble and the underlying Lower Schist unit were metamorphosed between the Late Cambrian and the Carboniferous and were extensively deformed during the Alpine orogeny. The Alpine deformation is considered to have occurred between the Early Cretaceous and the Oligocene. Granodiorites and rhyodacites of Oligocene age outcrop also in the area. The mineralization near Kato Nevrokopi is confined to intersecting Alpine fault zones of northeast and northwest trends. Negligible mineralization occurs into the schist, the richest orebodies being present as lateral extensions in the marble. Mineralization diminishes with increasing distance from the fault zones. The shape of the orebodies is irregular with individual offshoots being lenticular, pod-like or tabular. Sizes can be up to 50m in length, 20m in width and 5-10m in thickness. The boundaries between the orebodies and the marble are sharp and replacement and alteration phenomena around the orebodies include: dolomitization of the marble and clay mineral alteration. Two distinctly different mineralizing processes took place at Kato Nevrokopi: a) A hydrothermal process, characterized by mineral zoning in time and space, present as abundant rhodochrosite, ankerite, sphalerite, pyrite, pyrrhotine, chalcopyrite and marcasite in the stratigraphically deeper veins and "black calcite" (mixture of calcite and todorokite) and galena in the upper veins. b) A supergene process, in which the hydrothermal minerals in the veins were weathered. During this process, rhodochrosite in the veins was oxidized to MnO-gel and todorokite and in low altitude karstic cavities the mineral assemblage is: MnO-gel-nsutitechalcophanite. In high altitude karsts the mineral assemblage is: MnO-gel-nsutite-birnessite-cryptomelane-pyrolusite. During weathering Zn derived by dissolution of sphalerite was also mobile, being transported together with Mn to karstic cavities where it substituted for Mn in the Mn-oxides. The minerals pyrrhotine, marcasite, ankerite and birnessite are for first time recorded at Kato Nevrokopi. The lack of useable fluid inclusions severely limited the information on the composition of the hydrothermal fluids. From the mineral pair kaolinite-sericite, the pH of the hydrothermal fluids was estimated to have been between 3-4. Hydrothermal mineral precipitation took place mainly by reaction of the fluids with the marble and pH increase (cf., rhodochrosite) or by mixing of the hydrothermal fluids with near surface aquifers (black calcite). Thermodynamic data for the overall transformation of rhodochrosite to pyrolusite and the contemporaneous decomposition of chalcopyrite to azurite and malachite were used and the oxygen fugacity of the meteoric fluids was calculated to have ranged between 10-22 and 10-17. Mn-oxide precipitation during weathering took place either by oxidation of the primary veins (cf., MnO-gel, todorokite) or by reaction of the groundwaters with the marble in karstic cavities and precipitation of Mn-oxides as layers and encrustations above the local ground water table. Evidence from the whole rock geochemistry of the mineralized samples emphasizes the role of the thrust and fault zones as solution passageways and stresses their importance for the development of hydrothermal and supergene mineralization at Kato Nevrokopi. During weathering, downward percolation of C02-rich oxygenated meteoric waters within the veins, caused the breakdown and dissolution of sulphides and oxidation of rhodochrosite to Mn-oxides. The pH of these meteoric fluids was buffered by the dissolution of sulphides and the formation of karstic cavities was favoured by the high permeability induced by the occurrence of the thrust zone and the percolation of acidic meteoric waters through the marble. Chemical transport of MnZ+ to karstic cavities was possible in reduced meteoric waters at the beginning of weathering (pH"4-5), and as Mn(HCO3)2 in slightly alkaline groundwaters during advanced weathering (pH"6-8). Alkalies (K, Na) and alkaline earths (Ca, Mg, Ba, Sr) where leached away from the ore and the country rocks during weathering and the order of element mobility in the karstic cavities was: Na>K>MgaSr>Mn>As>Ca>Zn>Ba>Al>Fe>Cu>Cd>Pb. The Mn-oxide orebodies near Kato Nevrokopi are located in a northeast trending line parallel to the axes of major Alpine folds and significantly the rhyodacite volcanics outcrop also in a parallel fashion to this line providing evidence of an underlying pluton. This northeast trending line may therefore represent a zone of crustal weakness that was exploited by andesitic magma and subsequently by hydrothermal fluids. An average age of 33 Ma for the Kato Nevrokopi mineralization is provided. This age is similar to that of magmatism in and around the Drama area. It is therefore reasonable to conclude that the hydrothermal activity near Kato Nevrokopi and generally of the northeast Drama area was related to the Oligocene magmatism. On the basis of its age, style, morphology and genesis, the mineralization near Kato Nevrokopi is placed in the metallogenic province of N. Greece/S. Bulgaria which also includes the Madan hydrothermal Pb-Zn-Mn vein deposits and the Chalkidiki Pb-Zn deposits which have Mn-oxides in their upper parts.
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Lawson, Tamara. "Mechanistic studies of mineralisation in Escherichia coli." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445211.
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Pilkington, Michael Gerald. "Impacts of increased atmospheric nitrogen deposition on a Calluna vulgaris upland moor, North Wales." Thesis, Manchester Metropolitan University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273050.
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1. Long-term nitrogen (N) addition plots on an upland Cal/una vulgaris moor had been treated for more than ten years with 0,40, 80 and 120 kg N ha-1 yr- 1 • 2. Sampling of the soil solution from under the mor and the mineral gley horizons over an annual cycle revealed a high degree of retention of N, between 60 % and 80 % of ambient N inputs in the control, and rising to 90 % in response to higher inputs of the N treatments. 3. After passing through the mineral gley horizon, N was further retained, by 85 % of ambient N inputs in the control, and rising to 97 % in response to the highest N treatment. 4. There was some evidence of an inverse relation between ammonium and dissolved organic nitrogen (DON) under all N treatments. Microbial immobilisation and conversion to DON was compatible with the few significant effects on cation concentration, although calcium and calcium/aluminium ratios and pH were decreased by N treatment in the mineral gley horizon. 5. A budget revealed that the added N of the treatments had been allocated mainly to the canopy and litter at low inputs and increasingly to the mor, and to a lesser extent the gley horizon, with increasing N inputs. 6. In the system as a whole, 51 % of the entire system N was contained in the mor horizon, and with increasing inputs of added N, the whole system N accounted for 60 %, 80 % and 90 % of the added N in the low, middle and high N treatments respectively. 7. Nitrogen/phosphorus ratios in green tissue were decreased in response to increasing N inputs to levels indicative of N limitation, in spite of increases in phosphatase activity in the litter and mor layers. N uptake rates and mycorrhizal colonisation were not affected. 8. A moor management bum volatilised 90 % of the canopy N (amounting to 6 % of the total system N). Increases in the gain ofN in the gley horizon after the bum decreased with increasing N treatment, an indication of increasing N saturation in this layer and confirmed by increases in N leaching in response to higher N inputs. The same response was observed without significance in the mor layer owing to greater variance in the data. 9. Rates of net mineralisation and DON production in the litter layer increased with N inputs in both field and laboratory incubations, but net nitrification rate only showed N treatment-related increases in the laboratory incubation. Threshold values of litter % N and C/N ratios determined the onset of these processes, as well as N treatment-related increases in rates of potential denitrification. 10. Bryophyte cover under the Calluna canopy, density of the canopy, light transmission through the canopy and N inputs were all related, either negatively or positively (see chapter 5), but only in mature/degenerate plants. In "new' plots containing younger, building-phase Calluna, the addition of phosphorus raised the competitive ability of bryophytes above that of Calluna, particularly at lower inputs of N.
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Chee, Gan Poh. "Scale-up of an advanced oxidation process for the degradation of citric acid." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307046.
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Agabalyan, Natacha Anahid. "The role of the tenocyte in tendon mineralisation." Thesis, University of Brighton, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608309.
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Despite tendons being the core link in the musculoskeletal system, transmitting force from muscle to bone, they are particularly prone to injury and degeneration. Arising as large tissue tears in athletes or accumulations of microdamage in ageing individuals, the prevalence of tendon injury has risen over the past 20 years. The lack of knowledge of this tissue has particular implications when it comes to understanding how tendon responds to damage through injury, disease or ageing. It is not known why tenocytes, the tendon cells secreting the extracellular matrix composing the tissue, fail to fully repair degenerated tendon with a suitable matrix. Under certain conditions, tenocytes are able to mineralise their matrix, which may limit the ability of tendons to function normally. In several avian species including the domestic chicken (galfus galfus domesticus), tendons of the hindlimb undergo apparent spontaneous mineralisation. Although the appearance of mineralised avian tendon has been previously described, the cellular processes underlying this mechanism are poorly understood. It is possible that the tenocytes within the tendon play an important role. The nature of the mineralised avian tendon and its cells in the adult chicken was investigated. The adult tissue showed a loss of the crimp morphology that is usually evident in healthy tendon tissue and presented markers of mineralisation in the central part of the tendons. The tissue and the cells in the mineralised regions expressed chondrogenic and osteogenic markers as well as tenogenic markers marking a change in the tendon matrix. Tenocyte plasticity was investigated, revealing a sub-set of cells capable of differentiating down different lineages. Evidence has been gathered suggesting a source of pluripotent cells exists within the tendon tissue. The results of this study suggest tendon mineralisation within the adult avian tendon is the result of an endochondral process, driven by the proliferation and differentiation of progenitor-like cells within the tendon tissue. A better understanding of this process could hopefully lead to the development of treatments for cases of ectopic mineralisation due to ageing, disease or injury in the human population.
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Thomson, Brian. "Geology of silver mineralisation at Candelaria, Nevada, USA." Thesis, University of Aberdeen, 1990. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238078.
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Candelaria, situated in central western Nevada, along the western margin of the Great Basin, is a large and predominantly low grade, epigenetic disseminated- and vein-type Ag deposit, of Early Cretaceous age. It represents the eroded, deeply oxidised and fault-disrupted root of extensive stratiform quartz-dolomite stockworked and sericite-dolomite-altered zones of medium temperature pyrite-dominated Ag(-Pb-Zn-Sb-As±Cu±Au) sulphide-sulphosalt mineralisation, which is hosted by receptive sedimentary and igneous rocks within structurally favourable zones in a district-scale tectonic pinchout, and which is genetically associated with Cordilleran granodiorite porphyry hypabyssal magmatism (diking), of high K calc-alkaline affinity. The mineralisation occurs along and directly beneath the Pickhandle allochthon, a serpentinite-sheathed volcanic-sedimentary tectonic méange which forms a local 'sole' plate to the regionally extensive Golconda allochthon, which was emplaced onto the edge of continental North America during the Early Triassic Sonoma orogeny. Mineralisation occurred where an irregularity in the Pickhandle thrust plane, caused by thickening of the méange, effected locally deeper truncation of the parautochthonous foreland sequence in its footwall - chiefly marine sediments of the Lower Triassic Candelaria Formation - against the deformed cherts of the Ordovician basement (Palmetto complex), to form a structural trap. Within this trap, mineralisation is hosted mainly by carbonaceous, carbonate- and phosphate-rich (and trace metal-rich) black shales at the base of the Candelaria Formation and by dolomite-quartz-altered serpentinites at the base of the Pickhandle allochthon. Stable isotope data (O, H, S) point to a predominantly magmatic source for the hydrothermal fluids and ore sulphur, a source most likely to be the parent pluton to the granodiorite porphyry dikes. More ore metals were also of igneous origin (mass balance calculations rule out Candelaria member 1 as the chief metal source).
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Ouyang, Xiaoguang. "Exploring Carbon Mineralisation and Burial in Coastal Wetlands." Thesis, Griffith University, 2017. http://hdl.handle.net/10072/370678.
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Mangroves and saltmarshes are ‘blue carbon’ ecosystems and studies on their carbon (C) dynamics have become highly topical. In these coastal wetlands, the aboveground biomass sequesters C and allocates C to belowground roots. A significant portion of aboveground biomass is transferred to the sediment as litterfall. Belowground roots and their exudates are ultimately decomposed by microbial communities. As the product of root decomposition, CO2 is released from the sediment surface and organic C (OC) contributes to sediment C burial. In addition, the decomposition of litter and sediment organic material also contributes to CO2 efflux from the sediment surface. The patterns of belowground C dynamics in blue C ecosystems remain unclear, especially sediment C burial, root C decomposition, and the relative contributions of different sources to sediment CO2 efflux. Further, sediment CO2 efflux and C storage have typically been examined separately in past research. Improved understanding of these patterns will help consolidate the theory of C cycling in coastal wetlands and facilitate effective ‘blue C’ management. My thesis aims to fill these gaps via systematic quantitative reviews and synthesis of literature data, field surveys and laboratory microcosm experiments.
Studies on C stock in saltmarsh sediments have increased since the previous major review (Chmura et al., 2003). However, uncertainties exist in estimating global carbon storage in these vulnerable coastal habitats, thus hindering the assessment of their importance. Combining direct data and indirect estimation, my thesis compiled studies involving 143 sites across the southern and northern hemispheres, and provides an updated estimate of the global average carbon accumulation rate (CAR) at 244.7 g C m-2 yr-1 in saltmarsh sediments. Based on region-specific CAR and estimates of saltmarsh area in various geographic regions between 40°S to 69.7°N, total CAR in global saltmarsh sediments is estimated at ~ 10.2 Tg C yr-1. Latitude, tidal range and elevation appear to be important drivers for CAR of saltmarsh sediments, with considerable variation among different biogeographic regions. The data indicate that while the capacity for carbon sequestration by saltmarsh sediments ranked the first amongst coastal wetland and forested terrestrial ecosystems, their carbon budget was the smallest due to their limited and declining global areal extent. However, some uncertainties remain for this global estimate owing to limited data availability.
One of the aims of this thesis was to determine the drivers of root decomposition and its role in C budgets in mangroves and saltmarsh: the patterns of root decomposition, and its contribution to C budgets, in mangroves and saltmarsh. The impact of climatic (temperature and precipitation), geographic (latitude), temporal (decay period) and biotic (ecosystem type) drivers was explored using multiple regression models. Best-fit models explain 50% and 48% of the variance in mangrove and saltmarsh root decay rates, respectively. A combination of biotic, climatic, geographic and temporal drivers influence root decay rates. Rainfall and latitude have the strongest influence on root decomposition rates in saltmarsh. For mangroves, forest type is the most important; decomposition is faster in riverine mangroves than other types. Mangrove species Avicennia marina and saltmarsh species Spartina maritima and Phragmites australis have the highest root decomposition rates. Root decomposition rates of mangroves were slightly higher in the Indo-west Pacific region (average 0.16 % day-1) than in the Atlantic-east Pacific region (0.13 % day-1). Mangrove root decomposition rates also show a negative exponential relationship with porewater salinity. In mangroves, global root decomposition rates are 0.15 % day-1 based on the median value of rates in individual studies (and 0.14 % day-1 after adjusting for area of mangroves at different latitudes). In saltmarsh, global root decomposition rates average 0.12 % day-1 (no adjustment for area with latitude necessary). The global estimate of the amount of root decomposing is 10 Tg C yr-1 in mangroves (8 Tg C yr-1 adjusted for area by latitude) and 31 Tg C yr-1 in saltmarsh. Local root C burial rates reported herein are 51-54 g C m-2 yr-1 for mangroves (58-61 Tg C yr-1 adjusted for area by latitude) and 191 g C m-2 yr-1 for saltmarsh. These values account for 24.1-29.1% (mangroves) and 77.9% (saltmarsh) of the reported sediment C accumulation rates in these habitats. Globally, dead root C production is the significant source of stored sediment C in mangroves and saltmarsh.
Mangroves are blue carbon ecosystems that sequester significant carbon but release CO2, and to a lesser extent CH4, from the sediment through oxidation of organic carbon or from overlying water when flooded. Previous studies, e.g. Leopold et al. (2015), have investigated sediment organic C (SOC) content and CO2 flux separately, but did not provide a holistic perspective for both components of blue carbon. Based on field data from a mangrove in southeast Queensland, Australia, this thesis used a structural equation model to elucidate (1) the biotic and abiotic drivers of surface SOC (10 cm) and sediment CO2 flux; (2) the effect of SOC on sediment CO2 flux; and (3) the covariation among the environmental drivers assessed. Sediment water content, the percentage of fine-grained sediment (<63μm), surface sediment chlorophyll and light condition collectively drive sediment CO2 flux, explaining 41% of their variation. Sediment water content, the percentage of fine sediment, season, landform setting, mangrove species, sediment salinity and chlorophyll collectively drive surface SOC, explaining 93% of its variance. Sediment water content and the percentage of fine sediment have a negative impact on sediment CO2 flux but a positive effect on surface SOC content, while sediment chlorophyll is a positive driver of both. Surface SOC was significantly higher in Avicennia marina (2994±186 g m-2, mean+ SD) than in Rhizophora stylosa (2383± 209 g m-2). SOC was significantly higher in winter (2771±192 g m-2) than in summer (2599±211 g m-2). SOC significantly increased from creek-side (865±89 g m-2) through mid (3298±137 g m-2) to landward (3933±138g m-2) locations. Sediment salinity was a positive driver of SOC. Sediment CO2 flux without the influence of biogenic structures (crab burrows, aerial roots) averaged 15.4 mmol m-2 d-1 in A. marina stands under dark conditions, lower than the global average dark flux (61 mmol m-2 d-1) for mangroves.
CO2 flux is a critical component of the global C budget. While CO2 flux has been increasingly studied in mangroves, few studies partition components contributing to the flux. Partitioning CO2 flux sources helps constrain C budgets. We developed the combined 13C stable isotope labelling and closed chamber technique. The technique was used to partition CO2 efflux from the seedlings of mangrove Avicennia marina in laboratory microcosms, with a focus on sediment CO2 efflux. The result showed that (1) canopy was the chief component of ecosystem CO2 efflux, (2) the degradation of sediment organic matter was the major component of sediment CO2 efflux, followed by root respiration and litter decomposition via isotope mixing models. There was a significant relationship between δ13C values of CO2 released at the sediment-air interface and both root respiration and sediment organic matter decomposition. The findings provide the relative contribution of different components to ecosystem and sediment CO2 efflux, and thus can partition the sources of ecosystem respiration and sediment C mineralization in mangroves.
My thesis demonstrates that saltmarshes play a disproportionately important role in sediment C accumulation (244.7 g C m-2 yr-1) although their global area extent is declining, and saltmarsh CAR varies with latitude, tidal range, elevation and biogeographic regions. Dead root production contributes a significant proportion to sediment C in both mangroves and saltmarsh, and the updated global estimate of root C decomposition (8 Tg C yr-1) in mangroves reflects an underestimate in the reported value (5 Tg C yr-1). In a sub-tropical mangrove forest, SOC content and CO2 flux are influenced by sediment physio-chemical properties, and/or species, light conditions. Sediment water content and the percentage of fine sediment have contrasting effect on both but sediment chlorophyll is a positive driver of both, and these factors may be highlighted in ‘blue C’ management of this mangrove. In establishing mangroves (Avicennia marina), the result of a laboratory microcosm experiment shows that canopy was the major source of ecosystem CO2 efflux. The decomposition of roots contributes more to sediment CO2 efflux in comparison with sediment organic matter, which is in contrast to the pattern in mature mangroves.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Polya, D. A. J. "Chemical behaviour of tungsten in hydrothermal fluids." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378304.
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Evans, Jon Michael. "Gold exploration in tropically weathered terrains : the formation, evolution and geochemistry of lateritic profiles in Liberia and Guinea, West Africa." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395879.
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Diarra, Pobanou Hughes. "The geology and genesis of the Syama gold deposit, Mali, West Africa." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362528.
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Suzuki, Shuko. "In vitro mineralisation of well-defined polymers and surfaces." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16593/1/Shuko_Suzuki_Thesis.pdf.
Full textAbstract:
Currently, many polymeric biomaterials do not possess the most desirable surface properties for direct bone bonding due to the lack of suitable surface functionalities. The incorporation of negatively charged groups has been shown to enhance calcium phosphate formation in vitro and bone bonding ability in vivo. However, there are some conflicting literature reports that highlight the complicated nature of the mineralisation process as well as the sometimes apparent contradictory effect of the negatively charged groups. Surface modification using well-defined polymers offer a more precise control of the chain structures. The aims of this study were to synthesise well-defined polymers containing phosphate and carboxylic acid groups, and perform various surface modification techniques. The influence of the polymer structure on mineralisation was examined using a series of specially synthesised phosphate-containing polymers. The mineralisation ability of the fabricated surfaces was also tested.
Soluble poly(monoacryloxyethyl phosphate) (PMAEP) and poly(2-(methacryloyloxy)ethyl phosphate) (PMOEP) were synthesised using reversible addition fragmentation chain transfer (RAFT)-mediated polymerisation. The polymerisation conversions were monitored by in situ Raman spectroscopy. Subsequently 31P NMR investigation revealed the presence of large amounts of diene impurities as well as free orthophosphoric acids in both the MAEP and MOEP monomers. Elemental analyses of the polymers showed loss of phosphate groups due to hydrolysis during the polymerisation. Both gel and soluble PMAEP polymers were found to contain large amounts of carboxyl groups indicating hydrolysis at the C-O-C ester linkages. Block copolymers consisting of PMAEP or PMOEP and poly(2-(acetoacetoxy) ethyl methacrylate) PAAEMA were successfully prepared for the purpose of immobilisation of these polymers onto aminated slides.
Well-defined fluorinated polymers, (poly(pentafluorostyrene) (PFS), poly(tetrafluoropropyl acrylate) (TFPA) and poly(tetrafluoropropyl methacrylate) (TFPMA)) were synthesised by RAFT-mediated polymerisation. It was found that the Mn values of PFS at higher conversions were significantly lower than those calculated from the theory, although the PDI's were low (<1.1). One possible explanation for this is that it may be a result of the self-initiation of FS which created more chains than the added RAFT agents. Both TFPA and TFPMA showed well-controlled RAFT polymerisations. Chain extension of the fluorinated polymers with tert-butyl acrylate (tBA) followed by hydrolysis of the tBA groups produced the amphiphilic block copolymers containing carboxylic acid groups. Block copolymers consisting of PAAEMA segments were further reacted with glycine and L-phenylalanyl glycine.
Three types of surface modifications were carried out: Layer-by-Layer (LbL) assemblies of the soluble phosphate- and carboxylic acid-containing homopolymers, coupling reactions of block copolymers consisting of phosphate and keto groups onto aminated slides, and adsorption of fluorinated homo and block copolymers containing carboxylic acid groups onto PTFE. For LbL assemblies XPS analyses revealed that the thickness of the poly(acrylic acid) (PAA) layer was found to be strongly dependent on the pH at deposition. AFM images showed that the PMAEP LbL had a patchy morphology which was due to the carboxylate groups that were not deprotonated at low pH. Successful coupling of the block copolymers consisting of phosphate and keto groups onto aminated slides was evident in the XPS results. The conformation of attached P(MOEP-b-AAEMA) was investigated by ToF-SIMS. Adsorption of the fluorinated polymers onto the PTFE film was examined using different solvents. PFS showed the best adsorption onto PTFE. The block copolymers consisting of PFS and PtBA or PAA were successfully adsorbed onto PTFE. Contact angle measurements showed that the adsorbed block copolymers reorganised quickly to form a hydrophilic surface during the investigation.
In vitro mineralisation of various phosphate-containing polymers and the fabricated surfaces were studied using the simulated body fluid (SBF) technique. The SEM/EDX investigation showed that either brushite or monetite, with a tile-like morphology, was formed on both soluble and gel PMAEP polymers after seven days in SBF. The PMOEP gel formed a similar layer as well as a secondary growth of hydroxyapatite (HAP) that exhibited a typical globular morphology. Fourier transform infrared (FTIR) spectroscopy of the PMOEP film prepared from soluble PMOEP showed large amounts of carbonated HAP formation after seven days in SBF. Carbonated HAP is the phase that most closely resembles that found in biological systems. Both the LbL surfaces and the block copolymer-attached aminated slides showed only patchy mineralisation even after 14 days in SBF. This indicates that ionic interactions of the negatively charged phosphates or carboxylates and protonated amines prevented chelation of calcium ions, which is believed to be the first step in mineralisation. The P(FS-b-AA) adsorbed PTFE film also showed only small amounts of mineral formation after 14 days in SBF. These results highlight the many features controlling the mineralisation outcomes.
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Suzuki, Shuko. "In vitro mineralisation of well-defined polymers and surfaces." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16593/.
Full textAbstract:
Currently, many polymeric biomaterials do not possess the most desirable surface properties for direct bone bonding due to the lack of suitable surface functionalities. The incorporation of negatively charged groups has been shown to enhance calcium phosphate formation in vitro and bone bonding ability in vivo. However, there are some conflicting literature reports that highlight the complicated nature of the mineralisation process as well as the sometimes apparent contradictory effect of the negatively charged groups. Surface modification using well-defined polymers offer a more precise control of the chain structures. The aims of this study were to synthesise well-defined polymers containing phosphate and carboxylic acid groups, and perform various surface modification techniques. The influence of the polymer structure on mineralisation was examined using a series of specially synthesised phosphate-containing polymers. The mineralisation ability of the fabricated surfaces was also tested. Soluble poly(monoacryloxyethyl phosphate) (PMAEP) and poly(2-(methacryloyloxy)ethyl phosphate) (PMOEP) were synthesised using reversible addition fragmentation chain transfer (RAFT)-mediated polymerisation. The polymerisation conversions were monitored by in situ Raman spectroscopy. Subsequently 31P NMR investigation revealed the presence of large amounts of diene impurities as well as free orthophosphoric acids in both the MAEP and MOEP monomers. Elemental analyses of the polymers showed loss of phosphate groups due to hydrolysis during the polymerisation. Both gel and soluble PMAEP polymers were found to contain large amounts of carboxyl groups indicating hydrolysis at the C-O-C ester linkages. Block copolymers consisting of PMAEP or PMOEP and poly(2-(acetoacetoxy) ethyl methacrylate) PAAEMA were successfully prepared for the purpose of immobilisation of these polymers onto aminated slides. Well-defined fluorinated polymers, (poly(pentafluorostyrene) (PFS), poly(tetrafluoropropyl acrylate) (TFPA) and poly(tetrafluoropropyl methacrylate) (TFPMA)) were synthesised by RAFT-mediated polymerisation. It was found that the Mn values of PFS at higher conversions were significantly lower than those calculated from the theory, although the PDI's were low (<1.1). One possible explanation for this is that it may be a result of the self-initiation of FS which created more chains than the added RAFT agents. Both TFPA and TFPMA showed well-controlled RAFT polymerisations. Chain extension of the fluorinated polymers with tert-butyl acrylate (tBA) followed by hydrolysis of the tBA groups produced the amphiphilic block copolymers containing carboxylic acid groups. Block copolymers consisting of PAAEMA segments were further reacted with glycine and L-phenylalanyl glycine. Three types of surface modifications were carried out: Layer-by-Layer (LbL) assemblies of the soluble phosphate- and carboxylic acid-containing homopolymers, coupling reactions of block copolymers consisting of phosphate and keto groups onto aminated slides, and adsorption of fluorinated homo and block copolymers containing carboxylic acid groups onto PTFE. For LbL assemblies XPS analyses revealed that the thickness of the poly(acrylic acid) (PAA) layer was found to be strongly dependent on the pH at deposition. AFM images showed that the PMAEP LbL had a patchy morphology which was due to the carboxylate groups that were not deprotonated at low pH. Successful coupling of the block copolymers consisting of phosphate and keto groups onto aminated slides was evident in the XPS results. The conformation of attached P(MOEP-b-AAEMA) was investigated by ToF-SIMS. Adsorption of the fluorinated polymers onto the PTFE film was examined using different solvents. PFS showed the best adsorption onto PTFE. The block copolymers consisting of PFS and PtBA or PAA were successfully adsorbed onto PTFE. Contact angle measurements showed that the adsorbed block copolymers reorganised quickly to form a hydrophilic surface during the investigation. In vitro mineralisation of various phosphate-containing polymers and the fabricated surfaces were studied using the simulated body fluid (SBF) technique. The SEM/EDX investigation showed that either brushite or monetite, with a tile-like morphology, was formed on both soluble and gel PMAEP polymers after seven days in SBF. The PMOEP gel formed a similar layer as well as a secondary growth of hydroxyapatite (HAP) that exhibited a typical globular morphology. Fourier transform infrared (FTIR) spectroscopy of the PMOEP film prepared from soluble PMOEP showed large amounts of carbonated HAP formation after seven days in SBF. Carbonated HAP is the phase that most closely resembles that found in biological systems. Both the LbL surfaces and the block copolymer-attached aminated slides showed only patchy mineralisation even after 14 days in SBF. This indicates that ionic interactions of the negatively charged phosphates or carboxylates and protonated amines prevented chelation of calcium ions, which is believed to be the first step in mineralisation. The P(FS-b-AA) adsorbed PTFE film also showed only small amounts of mineral formation after 14 days in SBF. These results highlight the many features controlling the mineralisation outcomes.
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Turner, Andrew. "Vitamin D metabolism in an In Vitro mineralisation model /." Title page and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09SB/09sbt9438.pdf.
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Darke, K. E. "Supergene mineralisation in gold-rich Bolivian polymetallic vein deposits." Thesis, University of Aberdeen, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.592307.
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The Bolivian Au-rich polymetallic vein deposits (BPV) are associated with high level dacitic intrusives and volcanics, usually show pervasive phyllic alteration, and consist of massive sulfide veins. The deposits which have been studied, include the Kori Kollo gold mine (the largest gold project in Bolivia with sulfide ore reserves estimated at 65Mt.), the nearby Kiska prospect, and the prospects of La Riviera in the Western Cordillera and Escala in the southern Altiplano. Through the first detailed study of the geochemistry and mineralogy of the oxide zones, evidence of supergene processes within these deposits has been established. Visible and invisible supergene gold have been recognised, with a strong spatial association with jarosite, iron oxides and mixed-metal oxide phases. Oxide zone mineralogy has been used to establish the prevalence of extremely acidic, oxidizing conditions, thus favouring gold mobilisation as the short-lived halide and thiosulfate complexes, and leading to precipitation of gold via an adsorptive, colloidal or solid solution mechanism. Geochemical data has also shown halogens to be present in anomalous quantities in oxidized samples, thus supporting the hypothesis that gold was mobilised as halide complexes. The oxidation zones are rich in alunite (KAl3(SO4)2(OH)6) and jarosite (KFe3(SO4)2(OH)6), and stable isotope studies have been used to elucidate the origin of these sulfates. Sulfur isotope studies show that sulfides at all the deposits probably had a magmatic sulfur source. Complete analyses (δ34S, δ18O, δD) of alunite and jarosite indicate a supergene origin for these minerals at Kori Kollo, Kiska and Escala, but suggest that some jarosite at Kiska, and alunite at La Riviera, are hydrothermal in origin. The latter probably formed in a magmatic steam environment, suggesting the deposits to be expressions of near-surface hydrothermal systems. Oxygen and hydrogen isotope studies of the sulfate minerals indicate that the Miocene and Quaternary meteoric waters of the Altiplano were depleted in 18O and deuterium compared to the present day. K-Ar dating of sulfates show that supergene processes have occurred from at least 12Ma to the Quaternary on the Bolivian Altiplano. An accumulation of evidence suggests that the Altiplano has experienced a seasonally-dry, and semi-arid climate, at least since the Middle Miocene. Calculations reveal that the rate of weathering has been very slow in this environment.
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Gregory, R. G. "Soil gas emanometry and hydrothermal mineralisation in southwest England." Thesis, University of Exeter, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377311.
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Hajjawi, M. O. R. "Nucleotides as regulators of bone cell function and mineralisation." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1435412/.
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Most cells, including bone cells, release ATP into the extracellular environment. A considerable body of previous work has shown that ATP, acting through the P2 receptors, inhibits bone formation by osteoblasts and increases bone resorption by osteoclasts. This work focuses on the action of two key breakdown products of ATP, pyrophosphate and adenosine on bone cell function. Pyrophosphate, a ubiquitous physicochemical inhibitor of mineralisation, is formed from extracellular ATP by the action of ecto-nucleotide pyrophosphatase phosphodiesterases (NPPs); in bone these enzymes act in opposition to alkaline phosphatase. Adenosine, which can be generated in a number of ways from ATP, has been previously reported to stimulate both osteoblast and osteoclast function. However, using in vitro cultures, I found that it had little or no effect on the differentiation and bone forming capacity of rat osteoblasts, nor on the formation and resorptive function of mouse osteoclasts. I investigated the possibility that osteocytes, which form an interconnected cellular network within bone, might regulate mineralisation via NPPs. I found that cultured, primary osteocyte-like cells derived from mouse bone expressed Enpp1 mRNA. Osteocyte lacunae in the femora of Enpp1-/- mice imaged by scanning electron microscopy were found to be reduced in area by about 35%; indirect estimates of lacunar size using microCT imaging were in agreement. These results are consistent with the notion that ATP-derived pyrophosphate is important for maintenance of osteocyte lacunae size. Enpp1-/- mouse bones (humerus) were found to have reduced cortical bone diameter, reduced cortical porosity and an increased endosteal diameter compared to wild types, suggesting that the knockout phenotype also involves increased bone resorption and decreased bone formation. Histology and microCT of Enpp1-/- mice confirmed inappropriate joint mineralisation and showed that cartilage in the trachea and ear pinna was also mineralised, as were whisker sheaths. Osteoblasts, osteoclasts and osteocytes cultured in vitro from Enpp1-/- mice were found to release less ATP compared to cells from Enpp1+/+ mice in static conditions and after fluid flow stimulation. Enpp1-/- osteoblasts and osteoclasts also contained higher levels of intracellular ATP. Enpp1-/- osteoblasts showed increased bone production in vitro compared to Enpp1+/+; no effects of Enpp1 knockout on the formation or resorptive activity of osteoclasts were noted. Sclerostin, an osteocyte-derived inhibitor of WNT signalling and bone formation, was found to increase Enpp1 mRNA expression and NPP activity of osteoblasts, without affecting ALP in vitro. These results emphasise the importance of ATP and its breakdown product pyrophosphate in regulating mineralisation.
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Adamson, David W. "Volcanogenic mineralisation in the limestone lake area, Saskatchewan, Canada." Thesis, Aston University, 1988. http://publications.aston.ac.uk/14385/.
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This thesis describes the geology, geochemistry and mineralogy of a Lower Proterozoic, metamorphosed volcanogenic Cu-Zn deposit, situated at the western end of the Flin Flon greenstone belt. Stratabound copper mineralisation occurs in silicified and chloritoid-bearing alteration assemblages within felsic tuffs and is mantled by thin (< 3m) high-grade sphalerite layers. Mineralisation is underlain by garnet-hornblende bearing Lower Iron Formation (LIF), and overlain by garnet-grunerite bearing Upper Iron Formation (UIF). Distinctive trace element trends, involving Ti and Zr, in mineralised and footwall felsic tuffs are interpreted to have formed by fractionation associated with a high-level magma chamber in a caldera-type environment. Discrimination diagrams for basaltic rocks are interpreted to indicate their formation in an environment similar to that of recent, primitive, tholeiitic island arcs. Microprobe studies of key mineral phases demonstrate large and small scale chemical variations in silicate phases related to primary lithological, rather than metamorphic, controls. LIF is characterised by alumino-ferro-tschermakite and relatively Mn-poor, Ca-rich garnets, whereas UIF contains manganoan grunerite and Mn-rich garnets. Metamorphic mineral reactions are considered and possible precursor assemblages identified for garnet-, and chloritoid-bearing rocks. Chloritoid-bearing rocks are interpreted as the metamorphosed equivalents of iron-rich feeder zones formed near the surface. The iron-formations are thought to represent iron-rich sediments formed on the sea floor formed from the venting of the ore fluids. Consideration of various mineral assemblages leads to an estimate for peak metamorphic conditions of 450-500oC and > 4Kb total pressure. Comparisons with other volcanogenic deposits indicate affinities with deposits of `Mattabi-type' from the Archean of Ontario. An extrapolation of the main conclusions of the thesis to adjacent areas points to the presence of a number of geologically similar localities with potential for mineralisation.
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Horswell, Jacqueline. "Investigation of approaches to accelerate atrazine mineralisation in soil." Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU094707.
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Atrazine, a member of the s-triazine herbicides, appears on the EC Red List of chemicals that cause environmental concern, with residues occurring frequently in sub-soils and aquifers world-wide. Microbial metabolism is considered to be the major mechanism of complete removal of atrazine from the soil environment. Laboratory-based studies were carried out to investigate the microbial mineralisation of atrazine in soil, and to develop novel methods for potential acceleration of breakdown. In initial investigations, simple microcosm experiments were carried out to identify the importance of different fractions (water-soluble and water-insoluble) of plant residues to the dynamics, and extent of atrazine mineralisation. The amendment of soil with different plant residue fractions initially inhibited (for the water-soluble fraction) or enhanced (for the water-insoluble fraction) dynamics of atrazine mineralisation. However, by the end of the incubation, there was no overall effect on atrazine mineralisation. This suggested that increasing the soil organic matter content may render the herbicide less bioavailable to the degrader population. Investigations carried out to determine which component of the microbial biomass was more important in atrazine mineralisation showed that substantial removal of the fungal and Gram-negative bacterial population inhibited atrazine mineralisation in the soil. Experiments to selectively enrich the soil for fungal or bacterial atrazine degraders isolated a mixed bacterial culture able to accelerate atrazine mineralisation when inoculated into soil. The effect of the presence of the earthworm Lumbricus terrestris on the indigenous atrazine degrading microflora was investigated. Results indicated that atrazine mineralisation could be accelerated, but this was not primarily due to increases in microbial biomass, but possibly due to physio-chemical changes brought about by the earthworm and subsequent alterations in atrazine bioavailability.
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Lord, Richard Alastair. "Platinum-group element mineralisation in the Shetland ophiolite complex." Thesis, Open University, 1991. http://oro.open.ac.uk/57329/.
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The Shetland ophiolite complex exhibits the lower part of the definitive Penrose sequence, but chromitites from the Cliff locality contain levels of Pt and Pd which are unusual in ophiolites. Aspects of this mineralisation suggest both magmatic and hydrothermal concentration processes, although neither individually explain the observed paragenesis. This study examines the distribution of PGE within a representative fresh vertical section of the ophiolite stratigraphy, to assess the relative roles of such processes in the concentration and fractionation of PGE. In the field area around Balta Sound, tectonised mantle harzburgites are overlain by a layered ultramafic cumulate sequence. Accessory Ni-Cu sulphides occur throughout these cumulates. Two stratigraphically controlled zones of chromite enrichment have been identified which mark the bases of cyclic repetitions. Such chromite enrichments lack progressive changes in mineral chemistry so repetitions within the cumulate sequence are attributed to influxes of primitive magma during open system fractionation. The distribution of PGE and other chalcophiles show primary lithological associations, indicating a magmatic origin. Os-Ir-Ru concentrations occur in cbromitites, whereas Pt-PdRh concentrations occur in sulphide-bearing dunites, chromite-rich dunites, or basal pyroxenites. Stratigraphically controlled zones of PGE-enriched sulphide-bearing cumulate dunites occur close to the base of each cyclic repetition and are continuous over a strikelength of 2 km. The fractionation between PGE and other cha1cophiles is consistent with magmatic processes. The distribution and fractionation of PGE can be explained by an open system model. Negative slope patterns are produced by the precipitation of PGM from PGE saturated magmas during chromite crystallisation. This initial process buffers the PGE concentrations in each primitive magma pulse. On entering the axial chamber and mixing with the evolving resident magma, sulphide saturation occurs and the remaining PGE are partitioned into immiscible sulphide liquids. Multiple inputs result in repeated PGE enriched zones. This model explains why successive stratigraphic PGE-enriched horizons have similar positive slope patterns but progressively fractionated host silicate and sulphide compositions.
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Webber, D. M. "The application of quantitative cytochemical techniques to the study of bone turnover." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378804.
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McEwan, C. J. A. "Geology, geochemistry and stable isotope studies of an epithermal hydrothermal system, Rosita Hills, Colorado." Thesis, University of Aberdeen, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383565.
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The Rosita Hills volcanic centre is an alkali-calcic mid-Tertiary caldera complex overlying ortho- and paragneissic basement on the eastern margin of the Wet Mountains graben in southcentral Colorado. There were two mineralising events at the Rosita centre. Au, Ag and base metal mineralisation occurred in a phreatomagmatic breccia pipe at the northern margin of the complex. Later, Ag and base metal mineralisation occurred in veins in the centre of the complex. Mapping, petrological and XRD studies outline 4 alteration facies related to hydrothermal activity at the centre. Propylitic/argillic, K-feldspar-sericitic, advanced argillic and silicic alteration assemblages are recognised. The areas of most intense alteration are controlled by the dominant structural trends within the caldera. Sub-volcanic magma movement is postulated as the dominant cause of the fracture patterns. A lithogeochemical grid survey for Au, Ag, Sr, Rb, Cu, Pb, Zn and Mn across areas of hydrothermal alteration reveal complex patterns indicative of multi-stage hydrothermal activity. District-wide Sr, Zn and Mn depletions are related to the propylitic/argillic alteration. Au, Ag, Rb and Cu enhancements are related to the K-feldspar-sericite alteration. Late stage advanced argillic alteration modified the trace element dispersion patterns by leaching previously formed enhancements. Stable isotope studies (O and H) of whole rock and mineral separate (quartz and sericite) samples from veins and hydrothermal eruption breccias show that the hydrothermal fluid had both meteoric and magmatic components. δD values from whole rock samples show a crudely concentric pattern centring on areas of sericitic and advanced argillic alteration in the middle of the lithogeochemical grid. Fluid inclusion data from vein gangue minerals (quartz, baryte and sphalerite) and from silicified rock in the advanced argillic alteration zone again show that the hydrothermal fluid had more than one component fluid. A highly saline, high temperature fluid occurs in quartz associated with base metal mineralisation. Less saline inclusions occur in the upper parts of the system in the silicic alteration. The data indicate that mixing of these two end-member fluids precipitated the vein mineralisation. The source of metals in the Bassick breccia pipe orebody was a highly differentiated magma body underlying the breccia pipe. Incipient ring faulting probably controlled the emplacement of the magma. Other similar breccia pipes in Colorado are postulated as overlying Cu-Mo porphyry mineralisation. The source of the metals in the Rosita vein orebodies was the volcanic host rocks (and the Precambrian basement?). The Rosita Hills vein mineralisation shows features typical of adularia-sericite systems in the western United States. The Au:Ag ratio in these deposits can be related to the origins of the crust underlying the deposits.
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Redwood, S. D. "Epithermal precious and base metal mineralisation and related magmatism of the Northern Altiplano, Bolivian." Thesis, University of Aberdeen, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377620.
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The Bolivian Altiplano is part of the inner arc Polymetallic Belt of the Andes, and is a Cretaceous-Cenozoic intermontane basin located between the Andean arc of the Western Cordillera and the Paleozoic fold belt of the Eastern Cordillera. Reconnaissance geological mapping shows that epithermal mineralisation in the NE Altiplano is related to silicic magmatism located on NW-trending Altiplano growth faults and intersections with NE and E-W lineaments. Magmatism was episodic and occurred during the Miocene arc broadening episode, which correlates with increased plate convergence rates. Most magmatism is mid Miocene (19-10 Ma), and formed flow-dome-sill-stock complexes. The upper (9-7.5 Ma) and late (6.5-4 Ma) Miocene episodes, in contrast, generally formed ash-flow calderas and strato-volcanoes. The three episodes are mainly dacites and rhyolites of the high-K calc-alkaline suite, with some shoshonites, and can only be distinguished isotopically, with progressively stronger crustal contamination in the younger episodes. Sr-Nd-O isotopes and trace elements show that the magmas evolved by variable fractionation and assimilation from subduction-related, mantle-derived magmas which were isotopically enriched by bulk contamination with Precambrian gneisses. Mapping, petrography and XRD show that the epithermal deposits have large areas of pervasive phyllic alteration with a propylitic halo. Tourmaline alteration occurs in the cores of Sn-bearing deposits. Argillic and silicic alteration in some deposits are subsurface features of hot spring systems. Mineralisation (Au-Ag-Cu-Pb-Zn) is disseminated and in sheeted veins and veinlets which have a NE-trend, related to the regional tectonic stress. Dating and O-H isotopes show that the mineralisation is genetically related to the dacitic magmatism and formed from a dominantly magmatic fluid, with meteoric mixing in the upper levels. Differences between the Polymetallic Belt and the Copper Belt are mainly a function of erosion level. Polymetallic deposits of the Eastern Cordillera contain important Sn and form the main part of the Tin Belt. Minor Sn also occurs in Altiplano deposits hosted by Paleozoic marine sediments, but not in those in Tertiary red beds. Tin was probably derived from the Paleozoic sediments, and is not related to deep subduction.
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Banks, D. A. "On the origin of the Tynagh lead + zinc + copper deposit, Ireland." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382386.
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Röckl, Ludwig Otto. "The geology and genesis of a gold-rich, copper porphyry occurrence in the eastern Pontids, NE-Turkey." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246233.
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Lezot, Frédéric. "Interrelations des voies de regulation genetique et hormonale au cours de la biomineralisation dentaire, homeogenes msx et dlx et vitamine d." Paris 7, 2000. http://www.theses.fr/2000PA07GA02.
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Naden, Jonathan. "Gold mineralisation in the Caledonides of the British Isles with special reference to the Dolgellau gold belt, North Wales and the Southern Uplands, Scotland." Thesis, Aston University, 1988. http://publications.aston.ac.uk/14384/.
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Two aspects of gold mineralisation in the Caledonides of the British Isles have been investigated: gold-telluride mineralisation at Clogau Mine, North Wales; and placer gold mineralisation in the Southern Uplands, Scotland. The primary ore assemblage at Clogau Mine is pyrite, arsenopyrite, cobaltite, pyrrhotine, chalcopyrite, galena, tellurbismuth, tetradymite, altaite, hessite, native gold, wehrlite, hedleyite, native bismuth, bismuthunite and various sulphosalts. The generalised paragenesis is early Fe, Co, Cu, As and S species, and later minerals of Pb, Bi, Ag, Au, Te, Sb. Electron probe micro-analysis (EPMA) of complex telluride-sulphide intergrowths suggests that these intergrowths formed by co-crystallisation/replacement processes and not exsolution. Minor element chemical variation, in the sulphides and tellurides, indicates that antimony and cadmium are preferentially partitioned into telluride minerals. Mineral stability diagrams suggest that during gold deposition log bf aTe2 was between -7.9 and -9.7 and log bf aS2 between -12.4 and -13.8. Co-existing mineral assemblages indicate that the final stages of telluride mineralisation were between c. 250 - 275oC. It is suggested that the high-grade telluride ore shoot was the result of remobilisation of Au, Bi, Ag and Te from low grade mineralisation elsewhere within the vein system, and that gold deposition was brought about by destabilisation of gold chloride complexes by interaction with graphite, sulphides and tellurbismuth. Scanning electron microscopy of planer gold grains from the Southern Uplands, Scotland, indicates that detailed studies on the morphology of placer gold can be used to elucidate the history of gold in the placer environment. In total 18 different morphological characteristics were identified. These were divided on an empirical basis, using the relative degree of mechanical attrition, into proximal and distal characteristics. One morphological characteristic (a porous/spongy surface at high magnification) is considered to be chemical in origin and represent the growth of `new' gold in the placer environment. The geographical distribution of morphological characteristics has been examined and suggests that proximal placer gold is spatially associated with the Loch Doon, Cairsphairn and Fleet granitoids. Quantitative EPMA of the placer gold reveals two compositional populations of placer gold. Examination of the geographical distribution of fineness suggests a loose spatial association between granitoids and low fineness placer gold. Also identified was chemically heterogeneous placer gold. EPMA studies of these heterogeneities allowed estimation of annealing history limits, which suggest that the heterogeneities formed between 150 and 235oC. It is concluded, on the basis of relationships between morphology and composition, that there are two types of placer gold in the Southern Uplands: (i) placer gold which is directly inherited from a hypogene source probably spatially associated with granitoids; and (ii) placer gold that has formed during supergene processes.
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Goma-Tchimbakala, Joseph. "Dynamique de la matière organique et de l'azote en plantation de limba (terminale superba engler et diels) au Congo : comparaison avec une forêt naturelle." Paris 6, 2003. http://www.theses.fr/2003PA066437.
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Anderson, Duncan. "The relationship between magmatism and borate mineralisation in Western Turkey." Thesis, University of Leicester, 1997. http://hdl.handle.net/2381/30428.
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A limited number of lacustrine basins in western Turkey contain world class borate reserves, with mineralisation present as strata bound deposits in Neogene volcano-sedimentary successions. This study examined in detail the relationship between magmatism and borate mineralisation in two of these basins (Ernet and Kirka). The magmatism comprised an Early Miocene K-rich acid phase, represented by granite, ignimbrite, rhyolite and dacite, and a more mafic K-rich, Middle - Late Miocene phase, represented by shoshonite and latite. Information from field observations, mineralogy, isotopic dates, immobile element concentrations and biotite compositions indicate that acid magmatism in Ernet and Kirka Basins was closely related in both space and time to the deposition of the borate-host sediments, whilst mafic volcanism occurred later. The mineralogical and geochemical composition of the borate-host sediments was strongly influenced by the post-depositional modification of rhyolitic, ignimbritic and granitic-derived material in a saline, alkaline environment. The result of the interaction between saline, alkaline waters and dominantly acid igneous products, was the generation of an authigenic mineral assemblage comprising mainly calcite, dolomite, borate, trioctahedral smectite and K-feldspar. Trioctahedral smectite, dolomite and K-feldspar, together with elevated concentrations of As, Sr and Li, correlate particularly well with borate mineralisation. The geochemistry of the Early Miocene acid igneous rocks suggests that acid magmatism represented a likely source for B and Li, and probably also for As and Sr. Possible mechanisms for the transfer of B and other elements from an igneous source to the basin sediments include; transfer by igneous-driven geothermal fluids, rich in B as a result of hydrothermal leaching and contributions from magmatic waters and gases, and the breakdown of igneous material in saline, alkaline lakes. Trace element and Nd and Sr isotropic data indicate that the ultimate source of the B was assimilated upper continental crust, perhaps with some component of melted lithospheric mantle. Comparison with other borate provinces shows a common tectonic setting, characterised by former convergence with associated subduction and crustal thickening.
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Watkins, Naomi K. "The influence of crops on gross rates of nitrogen mineralisation." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333588.
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Walters, Martin. "The structural controls to mineralisation at Wheal Jane Mine, Cornwall." Thesis, University of Exeter, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358215.
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Hentrich, Doreen [Verfasser], and Andreas [Akademischer Betreuer] Taubert. "Grenzflächen-kontrollierte Mineralisation von Calciumphosphat / Doreen Hentrich ; Betreuer: Andreas Taubert." Potsdam : Universität Potsdam, 2017. http://d-nb.info/1218402466/34.
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Sim, Vivienne Jie Wei. "Physico-chemical changes and kinetics for mineralisation of EFB composting." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/1771.
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Composting is a biochemical process, highly dependent on temperature and aeration rate. This research aims at studying the mineral dynamics, developing an empirical model and optimising the composting of EFB. Mineralisation of nitrogen, phosphorus, potassium and calcium were found to be affected by both variables. Optimisation of the process shows the highest yield of nitrogen (1.86%) can be obtained at a temperature of 41.5°C and aeration rate of 0.37L/min.kg, over composting period of 42 days.
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Prout, Sarah Jane. "Petrology, geochemistry and mineralisation of the Ben Buie intrusion, Isle of Mull, and a brief survey of mineralisation in the Peridotite series, Cuillin Complex, Skye." Thesis, University of Exeter, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403209.
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Pinto, Henrique Senna Diniz. "Pyrochlore der Pegmatit-Provinz Nazareno, Brasilien Modellvorstellungen zu Mineralisation - Alteration - Kristallchemie /." [S.l. : s.n.], 2000. http://ArchiMeD.uni-mainz.de/pub/2000/0034/diss.pdf.
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Jali, Dulima Binti. "Nitrogen mineralisation, litter production and cellulose decomposition in tropical peat swamps." Thesis, Royal Holloway, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269744.
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Wang, Xiaolong. "Carbon dioxide capture and storage by mineralisation using recyclable ammonium salts." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12982/.
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Carbon dioxide capture and storage by mineralisation (CCSM) is considered to be an alternative solution for reducing anthropogenic C0₂in some regions, where geological storage is not possible or considered uneconomically viable. However, low efficiency of mineral dissolution and use of unrecyclable additives are two key barriers for the development of CCSM. A novel CCSM process with recyclable ammonium salts is proposed to overcome these barriers in this study. This process integrates mineral carbonation with C0₂capture by employing NH₃, NH₄HSO₄and C0₂containing ammonium salts in the capture step, mineral dissolution and carbonation steps, respectively. The NH₄HSO₄ and NH₃can then be regenerated by thermal decomposition of (NH₄)₂SO₄, which is the by-product from the process. The use of C0₂ containing ammonium salts as the source of C0₂can avoid desorption and compression of C0₂, which account for 70 % of the total energy consumption in the whole CCS chain. In this work, a CCSM process route at low solid to liquid ratio (50 g/I) was experimentally investigated to validate the process concept. It was found that the dissolution efficiency of magnesium (Mg) can achieve 100 % by using NH₄HSO₄and the carbonation efficiency can reach 96.5 % by using CO₂containing ammonium salts from the capture step and addition of aqueous NH₃. Three products, including Si rich residue, Fe rich residue and pure hydromagnesite were obtained from the process. The TGA studies reported that the regeneration efficiency of NH₄HSO₄ and NH₃ in this process was 95 %. Both dissolution and carbonation efficiencies achieved in this work are higher than the values reported in previous work. In order to reduce the water usage, a CCSM process at high solid to liquid ratio (200-300 g/I) was developed. It was found that the dissolution efficiency of Mg was 64 and 72 % at 200 and 300 g/l, respectively. The increase of dissolution efficiency with a solid to liquid ratio could be explained by the removal of passive product layer caused by particle-particle interaction. At a solid to liquid ratio of 300 g/l, the highest carbonation efficiency achieved was 65.4 %. Magnesite instead of hydromagnesite was found after carbonation due to the CO₂ pressure caused by the decomposition of ammonium salts above 70 °C. Additionally, the carbonation efficiency was doubled by using (NH₄)₂CO₃compared to that using NH₄HCO₃. A preliminary evaluation was conducted to estimate the OPEX, including energy consumption, chemical costs and feedstock cost, based on the experimental results from the two process routes developed. In order to get low OPEX, the optimization process conditions, such as solid to liquid ratio and reaction time, were determined. Then, experiments at these optimized conditions were conducted. The dissolution efficiency of Mg from serpentine with particle size 75-150 pm using 2.8 M NH₄HSO₄at 100 g/l solid to liquid ratio for 1h was around 80 %. The carbonation efficiency was 96 % when the molar ratio of Mg: CO₂ containing NH⁴+ salts: NH₃was 1: 1.5: 2. Thus, the mass balance of the process showed that 3.0 t' of serpentine, 0.2 t of NH₄HSO₄and 0.1 t of NH₃ were required to sequester 1t of CO₂and produce 1.9 t of magnesite. Moreover, 1.7 t of high Si content (46.9 wt. %) and 0.3 t of high Fe content (60 wt. %) were produced. Finally, a cost evaluation study including CAPEX and OPEX was made using Aspen plus software to simulate the optimized CCSM process with recyclable ammonium salts for a 100 MW coal-fired power plant. For the input of 60 t/h CO₂, 93 % of them can be sequestered by the process with 29.5 % energy consumption and the total carbon capture and storage costs was 71.8 US$/t CO₂sequestered, excluding the product sale.
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Wong, Alfred T. C. "Precipitation behaviour of calcium phosphate : a model for hard tissue mineralisation." Thesis, University of Oxford, 1993. http://ora.ox.ac.uk/objects/uuid:1d2e879d-0972-40ee-a931-664f5f043667.
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Various aspects of the precipitation behaviour of calcium phosphate in aqueous media have been investigated using seeded growth in conjuction with constant-volume and constant-composition techniques under different physical and chemical conditions. In each case, precipitation was allowed to proceed for up to seven days. The solid precipitates thus obtained were characterised by means of scanning electron microscopy, powder X-ray diffractometry and wavelength dispersive spectroscopy. During these precipitation experiments, the formation of the thermodynamically most stable and most supersaturated phase was invariably preceded by the appearance of less supersaturated precursor phase(s). These precursors subsequently underwent step-wise phase transformation into more stable phases. The preferred precursor and the rates of precipitation and phase transformation were dependent on the physical conditions and the chemical composition of the calcifying medium. Under physiological conditions, precipitation experiments were also carried out with the addition of certain non-collagenous bone-specific bio-chemicals. Phosphoserine dramatically accelerated the precipitation of a large quantity of small plate-like crystals, while osteonectin and phosphatidylserine induced the formation of quasi-cubic crystals at a slow rate. Bone protein extract displayed the strongest inhibitory effect on calcification. Bovine serum albumin showed signs of being irreversibly adsorbed to the crystal surface, thereupon inducing a high degree of calcium deficiency in the precipitate stoichiometry. Using a number of phosphorylated amino acids of different molecular masses, it was found that the processes of precipitation and phase transformation were facilitated by organic molecules whose phosphoryl functional groups were sterically accessible and highly electronegative. However, the acceleration brought about by the presence of a phosphorylated amino acid was maximised at an optimum concentration. The existence of such an optimum was very likely to be consequent of the competition for free calcium ions by the ongoing complexation and precipitation reactions. A model has also been developed to describe and predict the precipitation behaviour of calcium phosphate. The model is based on the Avrami-Johnson-Mehl expression for threedimensional nucleation and growth processes. Appropriate modifications to the original equation have been made, in order to adapt to this multi-ionic aqueous system. The resulting model has been found to describe the actual precipitation process accurately. It has also been applied to systems in which organic additives were present, and has again furnished predictions closely resembling the behaviour as observed experimentally.
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Poliquin, Morgan James. "Geology, geochemistry and age of intrusion-related mineralisation in eastern Mexico." Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/108354.
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Examination of igneous intrusions and related mineral deposits in eastern Mexico (including the determination of 26 new zircon U-Pb ages, 6 new mineral Ar-Ar ages and 26 new sulphide and feldspar Pb isotope and 61 new whole-rock geochemical data) revealed a spectrum of Eocene to Pleistocene mineral deposits and important aspects of the metallogenic history of Mexico. The synthesis of these data with recent tectonic reconstructions suggest the character of igneous rocks and mineral deposits was controlled by two periods of ocean ridge subduction and contemporaneous slab steepening and flattening. Mineralisation occurred in four epochs: (1) Eocene ~ 43 to 38 Ma Cu (Au) skarn and porphyry deposits in northeastern Mexico; (2) Miocene, ~18 to 9 Ma Cu (Au) porphyry, skarn and high-sulphidation epithermal deposits in the Trans Mexican Volcanic Belt (TMVB) and Oaxaca; (3) Pliocene ~ 4.5 Ma low-sulphidation epithermal deposits in the TMVB; and (4) Pliocene to Pleistocene ~ 2.5-2.0 Ma Cu (Au) skarn and porphyry deposits in Chiapas. The intrusions of the Eocene and Miocene epochs are high-K, have adakite-like geochemistry including Sr/Y up to ~108 and ~85 respectively and La/Yb ratios up to ~38 and ~27 respectively, and were followed by alkaline magmatism. All episodes of mineralisation are interpreted to have occurred above areas of slab steepening following periods of flat slab subduction. Shallow emplacement of Miocene ~ 9.0-8.0 Ma diorite stocks in the TMVB caused flashing of hydrothermal fluids, banded quartz vein formation and Au deposition which overprint potassic alteration and Cu-Au mineralisation. Barren quartz-alunite zones formed contemporaneously with potassic alteration at higher elevations. Later fluids deposited Au in some quartz-alunite zones. There is little difference in Pb isotope compositions of feldspar and sulphides or variation over time, their compositions ranging from 18.3208 to 19.1637 for 206Pb/204Pb, 15.4541 to 15.6675 for 207Pb/204Pb and 38.3096 to 39.2193 for 208Pb/204Pb. This may reflect similar tectonic environments and magma sources for Pb.
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LeBoutillier, Nicholas Gerald. "The tectonics of variscan magmatism and mineralisation in South West England." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275904.
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Murphy, Pamela Jane. "Fluid evolution related to gold mineralisation in the central Iberian zone." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241225.
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Roberts, Scott John. "The characterisation of mammalian PHOSPHO1 : an enzyme involved in bone mineralisation?" Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/11898.
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Skeletal mineralisation is dependent on the generation of inorganic phosphate (Pi), which has traditionally been attributed to tissue non-specific alkaline phosphatase (TNAP). However, evidence exists to suggest the presence of other Pi generating phosphatases in bone. The most compelling being that initial bone mineralisation events in newborn TNAP knockout mice appear to be normal, although abnormalities of the skeleton and dentition appear later. PHOSPHO1 is a phosphatase, which belongs to the haloacid dehalogenase (HAD) superfamily of magnesium-dependent hydrolyases. The work of this thesis has shown that PHOSPHO1 is able to catalyse the hydrolysis of phosphoethanolamine (PEA) and phosphocholine (PCho), which displays favourable kinetics under optimal conditions indicating that these reactions would occur in vivo. Site directed mutagenesis of active site residues, along with molecular modelling, confirm this enzyme as a member of the HAD superfamily as well as implicating residues in substrate specific interactions. PHOSPHO1 protein is localised to the mineralising sites of the skeleton and cells of bone and cartilage in the mouse model. Further to this PHOSPHO1 is present in an active state within matrix vesicles, the epicentre of mineral formation. Modulation of PHOSPHO1 activity through siRNA gene knockdown studies and specific PHOSPHO1 inhibitors leads to a decrease in the mineralization potential of cells and matrix vesicles respectively. These data further support the hypothesis that PHOSPHO1 plays a central role in matrix mineralization, and indicates that the function of PHOSPHO1 is to sequester Pi from PEA and PCho contained within the glycerolipid membrane of matrix vesicles.
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Ghee, Claire. "Mechanistic controls on the mineralisation and stabilisation of soil organic carbon." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=227956.
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Tabeart, Charles Frazer. "Structural and geochemical setting of gold mineralisation at Renco Mine, Zimbabwe." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47679.
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Steven, Nicholas Macrae. "Tungsten mineralisation at the Otjua prospect : a geological and geochemical investigation." Thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/22600.
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