Literatura académica sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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Artículos de revistas sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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Zou, Zhaoyong, Wouter J. E. M. Habraken, Galina Matveeva, Anders C. S. Jensen, Luca Bertinetti, Matthew A. Hood, Chang-yu Sun et al. "A hydrated crystalline calcium carbonate phase: Calcium carbonate hemihydrate". Science 363, n.º 6425 (24 de enero de 2019): 396–400. http://dx.doi.org/10.1126/science.aav0210.
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As one of the most abundant materials in the world, calcium carbonate, CaCO3, is the main constituent of the skeletons and shells of various marine organisms. It is used in the cement industry and plays a crucial role in the global carbon cycle and formation of sedimentary rocks. For more than a century, only three polymorphs of pure CaCO3—calcite, aragonite, and vaterite—were known to exist at ambient conditions, as well as two hydrated crystal phases, monohydrocalcite (CaCO3·1H2O) and ikaite (CaCO3·6H2O). While investigating the role of magnesium ions in crystallization pathways of amorphous calcium carbonate, we unexpectedly discovered an unknown crystalline phase, hemihydrate CaCO3·½H2O, with monoclinic structure. This discovery may have important implications in biomineralization, geology, and industrial processes based on hydration of CaCO3.
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Battaglia, Gianna, Marco Steinacher y Fortunat Joos. "A probabilistic assessment of calcium carbonate export and dissolution in the modern ocean". Biogeosciences 13, n.º 9 (13 de mayo de 2016): 2823–48. http://dx.doi.org/10.5194/bg-13-2823-2016.
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Abstract. The marine cycle of calcium carbonate (CaCO3) is an important element of the carbon cycle and co-governs the distribution of carbon and alkalinity within the ocean. However, CaCO3 export fluxes and mechanisms governing CaCO3 dissolution are highly uncertain. We present an observationally constrained, probabilistic assessment of the global and regional CaCO3 budgets. Parameters governing pelagic CaCO3 export fluxes and dissolution rates are sampled using a Monte Carlo scheme to construct a 1000-member ensemble with the Bern3D ocean model. Ensemble results are constrained by comparing simulated and observation-based fields of excess dissolved calcium carbonate (TA*). The minerals calcite and aragonite are modelled explicitly and ocean–sediment fluxes are considered. For local dissolution rates, either a strong or a weak dependency on CaCO3 saturation is assumed. In addition, there is the option to have saturation-independent dissolution above the saturation horizon. The median (and 68 % confidence interval) of the constrained model ensemble for global biogenic CaCO3 export is 0.90 (0.72–1.05) Gt C yr−1, that is within the lower half of previously published estimates (0.4–1.8 Gt C yr−1). The spatial pattern of CaCO3 export is broadly consistent with earlier assessments. Export is large in the Southern Ocean, the tropical Indo–Pacific, the northern Pacific and relatively small in the Atlantic. The constrained results are robust across a range of diapycnal mixing coefficients and, thus, ocean circulation strengths. Modelled ocean circulation and transport timescales for the different set-ups were further evaluated with CFC11 and radiocarbon observations. Parameters and mechanisms governing dissolution are hardly constrained by either the TA* data or the current compilation of CaCO3 flux measurements such that model realisations with and without saturation-dependent dissolution achieve skill. We suggest applying saturation-independent dissolution rates in Earth system models to minimise computational costs.
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Fischer, M., D. N. Thomas, A. Krell, G. Nehrke, J. Göttlicher, L. Norman, C. Riaux-Gobin y G. S. Dieckmann. "Quantification of ikaite in Antarctic sea ice". Cryosphere Discussions 6, n.º 1 (3 de febrero de 2012): 505–30. http://dx.doi.org/10.5194/tcd-6-505-2012.
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Abstract. Calcium carbonate precipitation in sea ice can increase pCO2 during precipitation in winter and decrease pCO2 during dissolution in spring. CaCO3 precipitation in sea ice is thought to potentially drive significant CO2 uptake by the ocean. However, little is known about the quantitative spatial and temporal distribution of CaCO3 within sea ice. This is the first quantitative study of hydrous calcium carbonate, as ikaite, in sea ice and discusses its potential significance for the carbon cycle in polar oceans. Ice cores and brine samples were collected from pack and land fast sea ice between September and December 2007 during an expedition in the East Antarctic and another off Terre Adélie, Antarctica. Samples were analysed for CaCO3, Salinity, DOC, DON, Phosphate, and total alkalinity. A relationship between the measured parameters and CaCO3 precipitation could not be observed. We found calcium carbonate, as ikaite, mostly in the top layer of sea ice with values up to 126 mg ikaite per liter melted sea ice. This potentially represents a contribution between 0.12 and 9 Tg C to the annual carbon flux in polar oceans. The horizontal distribution of ikaite in sea ice was heterogenous. We also found the precipitate in the snow on top of the sea ice.
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Battaglia, G., M. Steinacher y F. Joos. "A probabilistic assessment of calcium carbonate export and dissolution in the modern ocean". Biogeosciences Discussions 12, n.º 24 (21 de diciembre de 2015): 20223–82. http://dx.doi.org/10.5194/bgd-12-20223-2015.
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Abstract. The marine cycle of calcium carbonate (CaCO3) is an important element of the carbon cycle and co-governs the distribution of carbon and alkalinity within the ocean. However, CaCO3 fluxes and mechanisms governing CaCO3 dissolution are highly uncertain. We present an observationally-constrained, probabilistic assessment of the global and regional CaCO3 budgets. Parameters governing pelagic CaCO3 export fluxes and dissolution rates are sampled using a Latin-Hypercube scheme to construct a 1000 member ensemble with the Bern3D ocean model. Ensemble results are constrained by comparing simulated and observation-based fields of excess dissolved calcium carbonate (TA*). The minerals calcite and aragonite are modelled explicitly and ocean–sediment fluxes are considered. For local dissolution rates either a strong, a weak or no dependency on CaCO3 saturation is assumed. Median (68 % confidence interval) global CaCO3 export is 0.82 (0.67–0.98) Gt PIC yr−1, within the lower half of previously published estimates (0.4–1.8 Gt PIC yr−1). The spatial pattern of CaCO3 export is broadly consistent with earlier assessments. Export is large in the Southern Ocean, the tropical Indo–Pacific, the northern Pacific and relatively small in the Atlantic. Dissolution within the 200 to 1500 m depth range (0.33; 0.26–0.40 Gt PIC yr−1) is substantially lower than inferred from the TA*-CFC age method (1 ± 0.5 Gt PIC yr−1). The latter estimate is likely biased high as the TA*-CFC method neglects transport. The constrained results are robust across a range of diapycnal mixing coefficients and, thus, ocean circulation strengths. Modelled ocean circulation and transport time scales for the different setups were further evaluated with CFC11 and radiocarbon observations. Parameters and mechanisms governing dissolution are hardly constrained by either the TA* data or the current compilation of CaCO3 flux measurements such that model realisations with and without saturation-dependent dissolution achieve skill. We suggest to apply saturation-independent dissolution rates in Earth System Models to minimise computational costs.
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Gong, Dehong, Zhongxiao Zhang y Ting Zhao. "Decay on Cyclic CO2 Capture Performance of Calcium-Based Sorbents Derived from Wasted Precursors in Multicycles". Energies 15, n.º 9 (3 de mayo de 2022): 3335. http://dx.doi.org/10.3390/en15093335.
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In order to obtain the cheap waste calcium-based sorbent, three wasted CaCO3 precursors, namely carbide slag, chicken eggshells, and analytical reagent-grade calcium carbonate, were selected and prepared at 700 °C to form calcium-based sorbents for CO2 capture. TGA was used to test the CO2 uptake performance of each calcium-based sorbent in 20 cycles. To identify the decay mechanism of CO2 uptake with an increasing number of cycles, all calcium-based sorbents were characterized by using XRF, XRD, and N2 adsorption. The specific surface area of calcium-based sorbents was used to redefine the formula of cyclic carbonation reactivity decay. The carbonation conversion rate of three calcium-based sorbents exhibited a decreasing trend as the cycle number increased. Chicken eggshells exhibited the most significant decrease rate (over 50% compared with Cycle 1), while carbide slag and analytical reagent-grade calcium carbonate showed a flat linear decline trend. The specific surface area of the samples was used to calculate carbonation conversion for an infinite number of cycles. The carbonation conversion rates of three calcium-based sorbents were estimated to decrease to 0.2898, 0.1455, and 0.3438 mol/mol, respectively, after 100 cycles.
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Chafidz, Achmad. "Polypropylene/CaCO<sub>3</sub> Nanocomposites Fabricated Using Masterbatch: Effect of Nano-CaCO<sub>3</sub> Loadings and Re-Processing on the Melting Properties". Materials Science Forum 1067 (10 de agosto de 2022): 73–78. http://dx.doi.org/10.4028/p-2u9f04.
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Polypropylene filled calcium carbonate (CaCO3) nanocomposites were fabricated by employing melt blending/compounding method using masterbatch. To investigate the efffect of reprocessing on the melting properties of PP/CaCO3 nanocomposites, the melt compounding process was conducted twice (two cycles). The effect of nano-CaCO3 loadings (i.e. 5, 10 and 15 wt%) on the melting properties of PP/CaCO3 nanocomposites were also studied. The meling properties of the nanocomposites were analyzed by using a DSC (Differential Scanning Calorimetry). Additionally, the nanocomposites samples were also analyzed by an SEM (Scanning Electron Microscopy). The SEM analysis results revealed that at higher nano-CaCO3 loading (i.e. 15 wt%), the nano-CaCO3 particles in the 2nd cycle were more well distributed/dispersed in the polypropylene matrix as compared to the 1st cycle. Whereas, the DSC test results showed that the crystallinity of the nanocomposites samples were similar to that of neat PP for the 1st cycle of melt blending process, which was about 41%. In the other hand, for the 2nd cycle, the crystallinity of the samples slightly increased wtih increasing nano-CaCO3 loadings, which were about 39.6; 43; 44% for nano-CaCO3 loadings of 0, 5, 10 wt%, respectively. Nevertheless, at the highest nano-CaCO3 loadings (i.e. 15 wt%), the crystallinity of the nanocomposites (i.e. NCC-15-II) decreased again and lower than that of neat PP, which was about 37.7%.
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Dieckmann, G. S., G. Nehrke, C. Uhlig, J. Göttlicher, S. Gerland, M. A. Granskog y D. N. Thomas. "Brief communication: ikaite (CaCO<sub>3</sub>*6H<sub>2</sub>O) discovered in Arctic sea ice". Cryosphere Discussions 4, n.º 1 (9 de febrero de 2010): 153–61. http://dx.doi.org/10.5194/tcd-4-153-2010.
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Abstract. We report for the first time on the discovery of calcium carbonate crystals as ikaite (CaCO3*6H2O) in sea ice from the Arctic (Kongsfjorden, Svalbard). This finding demonstrates that the precipitation of calcium carbonate during the freezing of sea ice is not restricted to the Antarctic, where it was observed for the first time in 2008. This finding is an important step in the quest to quantify its impact on the sea ice driven carbon cycle and should in the future enable improvement parametrization sea ice carbon models.
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Dieckmann, G. S., G. Nehrke, C. Uhlig, J. Göttlicher, S. Gerland, M. A. Granskog y D. N. Thomas. "Brief Communication: Ikaite (CaCO<sub>3</sub>·6H<sub>2</sub>O) discovered in Arctic sea ice". Cryosphere 4, n.º 2 (28 de mayo de 2010): 227–30. http://dx.doi.org/10.5194/tc-4-227-2010.
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Abstract. We report for the first time on the discovery of calcium carbonate crystals as ikaite (CaCO3·6H2O) in sea ice from the Arctic (Kongsfjorden, Svalbard) as confirmed by morphology and indirectly by X-ray diffraction as well as XANES spectroscopy of its amorophous decomposition product. This finding demonstrates that the precipitation of calcium carbonate during the freezing of sea ice is not restricted to the Antarctic, where it was observed for the first time in 2008. This observation is an important step in the quest to quantify its impact on the sea ice driven carbon cycle.
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Rigual Hernández, Andrés S., Thomas W. Trull, Scott D. Nodder, José A. Flores, Helen Bostock, Fátima Abrantes, Ruth S. Eriksen et al. "Coccolithophore biodiversity controls carbonate export in the Southern Ocean". Biogeosciences 17, n.º 1 (17 de enero de 2020): 245–63. http://dx.doi.org/10.5194/bg-17-245-2020.
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Abstract. Southern Ocean waters are projected to undergo profound changes in their physical and chemical properties in the coming decades. Coccolithophore blooms in the Southern Ocean are thought to account for a major fraction of the global marine calcium carbonate (CaCO3) production and export to the deep sea. Therefore, changes in the composition and abundance of Southern Ocean coccolithophore populations are likely to alter the marine carbon cycle, with feedbacks to the rate of global climate change. However, the contribution of coccolithophores to CaCO3 export in the Southern Ocean is uncertain, particularly in the circumpolar subantarctic zone that represents about half of the areal extent of the Southern Ocean and where coccolithophores are most abundant. Here, we present measurements of annual CaCO3 flux and quantitatively partition them amongst coccolithophore species and heterotrophic calcifiers at two sites representative of a large portion of the subantarctic zone. We find that coccolithophores account for a major fraction of the annual CaCO3 export, with the highest contributions in waters with low algal biomass accumulations. Notably, our analysis reveals that although Emiliania huxleyi is an important vector for CaCO3 export to the deep sea, less abundant but larger species account for most of the annual coccolithophore CaCO3 flux. This observation contrasts with the generally accepted notion that high particulate inorganic carbon accumulations during the austral summer in the subantarctic Southern Ocean are mainly caused by E. huxleyi blooms. It appears likely that the climate-induced migration of oceanic fronts will initially result in the poleward expansion of large coccolithophore species increasing CaCO3 production. However, subantarctic coccolithophore populations will eventually diminish as acidification overwhelms those changes. Overall, our analysis emphasizes the need for species-centred studies to improve our ability to project future changes in phytoplankton communities and their influence on marine biogeochemical cycles.
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Anggoro, B. M. y A. Sugandi. "Effect of Calcium Carbonate Application on Initial Vegetative Growth of Oil Palm Planted on Deep Peat". IOP Conference Series: Earth and Environmental Science 1308, n.º 1 (1 de febrero de 2024): 012027. http://dx.doi.org/10.1088/1755-1315/1308/1/012027.
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Abstract The main challenge of planting oil palm on deep peat is naturally acidic soil pH which affects rooting development and activity and uptake of nutrients. Considering one life cycle of oil palm can be up to ≥20 years, ensuring optimum growth of palms since its initial planting is essential. Calcium carbonate (CaCO3) application is a standard practice to increase soil pH, including on peat soils. However, the effective rate and effects of its application to palm growth are still lacking. This trial is aimed to see the effect of CaCO3 application on the vegetative growth of oil palms planted on deep peat in the initial years of planting. The trial was conducted in an oil palm plantation in Pangkalan Kerinci-Riau with a split-plot randomized complete block design. Basal application of CaCO3 for the first three consecutive years of planting with three different rates and additional rates of CaCO3 and liquid lime per palm basis were the main and sub-treatments of this trial. Significant differences were found in frond length, leaf area, leaf area index, and frond dry weight at the immature stage in which palms treated with basal CaCO3 showed better growth. At the young mature stage, significant differences were found only in leaf area, leaf area index, and the number of green fronds. A significant difference for sub-treatment was found only in the leaf area index. The result indicated that application of CaCO3 as basal application during immature stage could improve palm’s growth whereas additional CaCO3 per palm basis may not necessarily result in better growth.
Tesis sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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Planchat, Alban. "Alkalinity and calcium carbonate in Earth system models, and implications for the ocean carbon cycle". Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLE005.
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L’alcalinité de l’océan (Alk) est essentielle dans l’absorption de carbone atmosphérique et offre une capacité tampon contre l’acidification. Dans le cadre des prévisions de l’absorption de carbone par les océans et des impacts potentiels sur les écosystèmes, la représentation de l’Alk et du principal facteur de sa distribution dans l’océan profond, le cycle du carbonate de calcium (CaCO3), ont souvent été négligés. Cette thèse aborde le manque de considération accordé à l’Alk et au cycle du CaCO3 dans les modèles du système terrestre (ESM) et explore les implications pour le cycle du carbone dans un océan pré-industriel ainsi que dans des scénarios de changement climatique. À travers une intercomparaison des ESMs, une réduction des biais simulés de l’Alk dans la 6ème phase du Projet d’Intercomparaison de Modèles Couplés (CMIP6) est rapportée. Cette réduction peut s’expliquer partiellement par une calcification pélagique accrue, redistribuant l’Alk en surface et renforçant son gradient vertical dans la colonne d’eau. Une revue des modèles de biogéochimie marine utilisés dans les ESMs actuels révèle une représentation diverse du cycle du CaCO3 et des processus affectant l’Alk. Les schémas de paramétrisation de la production, de l’exportation, de la dissolution et de l’enfouissement du CaCO3 varient considérablement, avec une prise en compte généralement limitée à la seule calcite, et sans calcification benthique. Cette diversité entraîne des projections contrastées de l’export de carbone associé au CaCO3 depuis l’océan de surface vers l’océan profond dans les scénarios futurs. Cependant, des simulations de sensibilité effectuées avec le modèle de biogéochimie marine NEMO-PISCES indiquent que la rétroaction associée sur le flux de carbone anthropique et l’acidification des océans reste limitée. À travers un ensemble de simulations NEMO-PISCES, il est démontré qu’une attention particulière au bilan d’Alk est cruciale pour estimer le dégazage de carbone océanique pré-industriel dû aux apports fluviaux ainsi qu’à l’enfouissement de matière organique et de CaCO3. De telles estimations sont fondamentales pour évaluer le flux de carbone air-mer anthropique en utilisant des données d’observation, et mettent en évidence la nécessité de mieux contraindre le bilan d’Alk de l’océan. Enfin, fidèle au message qu’elle véhicule sur le changement climatique, cette thèse offre une perspective nouvelle et radicale sur les sciences du climat et le système de la recherche actuelOcean alkalinity (Alk) is critical for the uptake of atmospheric carbon and provides buffering capacity against acidification. Within the context of projections of ocean carbon uptake and potential ecosystem impacts, the representation of Alk and the main driver of its distribution in the ocean interior, the calcium carbonate (CaCO3) cycle, have often been overlooked. This thesis addresses the lack of consideration given to Alk and the CaCO3 cycle in Earth system models (ESMs) and explores the implications for the carbon cycle in a pre-industrial ocean as well as under climate change scenarios. Through an ESM intercomparison, a reduction in simulated Alk biases in the 6th phase of the Coupled Model Intercomparison Project (CMIP6) is reported. This reduction can be partially explained by increased pelagic calcification, redistributing Alk at the surface and strengthening its vertical gradient in the water column. A review of the ocean biogeochemical models used in current ESMs reveals a diverse representation of the CaCO3 cycle and processes affecting Alk. Parameterization schemes for CaCO3 production, export, dissolution, and burial vary substantially, with no benthic calcification and generally only calcite considered. This diversity leads to contrasting projections of carbon export associated with CaCO3 from the surface ocean to the ocean interior in future scenarios. However, sensitivity simulations performed with the NEMO-PISCES ocean biogeochemical model indicate that the feedback of this on anthropogenic carbon fluxes and ocean acidification remains limited. Through an ensemble of NEMO-PISCES simulations, careful consideration of the Alk budget is shown to be critical to estimating pre-industrial ocean carbon outgassing due to riverine discharge and the burial of organic matter and CaCO3. Such estimates are fundamental to assessing anthropogenic air-sea carbon fluxes using observational data and highlight the need for greater constraints on the ocean Alk budget
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au, vicky whiffin@sydneywater com y Victoria S. Whiffin. "Microbial CaCO3 precipitation for the production of biocement". Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20041101.142604.
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The hydrolysis of urea by the widely distributed enzyme urease is special in that it is one of the few biologically occurring reactions that can generate carbonate ions without an associated production of protons. When this hydrolysis occurs in a calcium-rich environment, calcite (calcium carbonate) precipitates from solution forming a solid-crystalline material. The binding strength of the precipitated crystals is highly dependent on the rate of carbonate formation and under suitable conditions it is possible to control the reaction to generate hard binding calcite cement (or Biocement). The objective of this thesis was to develop an industrially suitable cost-effective microbial process for the production of urease active cells and investigate the potential for urease active cells to act as a catalyst for the production of Biocement.
The biocementation capability of two suitable strains was compared. Sporosarcina pasteurii (formally Bacillus pasteurii) produced significantly higher levels of urease activity compared to Proteus vulgaris, however the level of urease activity was variable with respect to biomass suggesting that the enzyme was not constitutive as indicated by the literature, but subject to regulation. The environmental and physiological conditions for maximum urease activity in S. pasteurii were investigated and it was found that the potential urease capacity of the organism was very high (29 mM urea.min-1.OD-1) and sufficient for biocementation without additional processing (e.g. concentration, cell lysis). The regulation mechanism for S. pasteurii urease was not fully elucidated in this study, however it was shown that low specific urease activity was not due to depletion of urea nor due to the high concentrations of the main reaction product, ammonium. pH conditions were shown to have a regulatory effect on urease but it was evident that another co-regulating mechanism existed. Despite not fully exploiting the urease capability of S. pasteurii, sufficient urease activity to allow direct application of the enzyme without additional processing could still be achieved and the organism was considered suitable for biocementation.
Urease was the most expensive component of the cementation process and cost-efficient production was desired, thus an economic growth procedure was developed for large-scale cultivation of S. pasteurii. The organism is a moderate alkaliphile (growth optimum pH 9.25) and it was shown that sufficient activity for biocementation could be cultivated in non-sterile conditions with a minimum of upstream and downstream processing. The cultivation medium was economised and expensive components were replace with a food-grade protein source and acetate, which lowered production costs by 95%. A high level of urease activity (21 mM urea hydrolysed.min-1) was produced in the new medium at a low cost ($0.20 (AUD) per L).
The performance of urease in whole S. pasteurii cells was evaluated under biocementation conditions (i.e. presence of high concentrations of urea, Ca2+, NH4 +/NH3, NO3 - and Cl- ions). It was established that the rate of urea hydrolysis was not constant during cementation, but largely controlled by the external concentrations of urea and calcium, which constantly changed during cementation due to precipitation of solid calcium carbonate from the system. A simple model was generated that predicted the change in urea hydrolysis rate over the course of cementation. It was shown that whole cell S. pasteurii urease was tolerant to concentrations of up to 3 M urea and 2 M calcium, and the rate of urea hydrolysis was unaffected up to by 3 M ammonium. This allowed the controlled precipitation of up to 1.5 M CaCO3 within one treatment, and indicated that the enzyme was very stable inspite of extreme chemical conditions.
A cost-efficient cementation procedure for the production of high cementation strength was developed. Several biocementation trials were conducted into order to optimise the imparted cementation strength by determining the effect of urea hydrolysis rate on the development of strength. It was shown that high cementation strength was produced at low urea hydrolysis rates and that the development of cementation strength was not linear over the course of the reaction but mostly occurred in the first few hours of the reaction. In addition, the whole cell bacterial enzyme had capacity to be immobilised in the cementation material and re-used to subsequent applications, offering a significant cost-saving to the process.
An industry-sponsored trial was undertaken to investigate the effectiveness of Biocement for increasing in-situ strength and stiffness of two different sandy soils; (a) Koolschijn sand and (b) 90% Koolschijn sand mixed with 10% peat (Holland Veen). After biocementation treatment, Koolschijn sand indicated a shear strength of 1.8 MPa and a stiffness of 250 MPa, which represents an 8-fold and 3-fold respective improvement in strength compared to unconsolidated sand. Significantly lower strength improvements were observed in sand mixed with peat.
In combination, trials of producing bacteria under economically acceptable conditions and cementation trials support the possibility of on-site production and in-situ application of large field applications.
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Derrien, Anne-Cécile. "Synthèse et caractérisation physico-chimique de géopolymères. Application cinétique de minéralisation de géopolymères et du biomatériau CaCO3 synthétique". Rennes 1, 2004. https://tel.archives-ouvertes.fr/tel-00007911.
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Les chirurgiens sont confrontés à des pertes de substance osseuse qui impliquent l'utilisation de biomatériaux synthétiques de comblement. Leur utilisation permet de limiter les réponses immunitaires et leur disponibilité est quasi illimitée. Notre travail a porté sur des géopolymères (Si/Al=21). Ces aluminosilicates synthétisés ont été associés à des phosphates de calcium. Chauffés à 500ʿC, les géopolymères présentent des pH de 7 et un bon compromis propriétés mécaniques/ porosité. Ces matériaux ont été étudiés in vitro et in vivo pour évaluer leur potentiel pour une utilisation comme biomatériaux. Les cinétiques de minéralisation des géopolymères et du biomatériau CaCO3 ont été étudiées. Les résultats obtenus par PIXE et NAA pour le CaCO3 montrent un comportement in vivo similaire à celui d'un TCP. Les études in vivo réalisées sur les géopolymères ont confirmé l’ostéointégration des implants. Les analyses par PIXE des implants confirment la consolidation de l'interface dès 1 mois.
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Marquina, Edgar Alberto. "Use of Dynamic Mechanical Testing, WAXD and SEM Image Analysis to Study the Properties of Polypropylene/Calcium Carbonate Nanocomposites". University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1269363578.
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Ouhenia, Salim. "Simulation des diagrammes de diffraction par la méthode combinée : application aux systèmes CaCO3". Caen, 2008. http://www.theses.fr/2008CAEN2080.
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Le développement considérable réalisé ces dix dernières années dans les techniques de diffraction sur des échantillons sous forme de poudre même très texturés (temps d’enregistrement raisonnable et très bonne résolution) et les progrès fascinants des moyens de calcul sur des machines individuelles rendent possible l’accès à des informations précises et avec des temps de calcul raisonnablement courts. Dans ce travail, nous avons appliqué l’analyse combinée basée sur la méthode de Rietveld pour étudier des échantillons de carbonates de calcium naturels de coquilles de certaines espèces de mollusques (structure, texture, tailles anisotropes…etc. ) et synthétiques par biomimétisme dans le but de comprendre l’influence des différents facteurs intervenants dans la croissance et la forme des grains des différents polymorphes de CaCO3. Dans les échantillons naturels, nous avons clairement mis en évidence l’existence de déformations de mailles cristallines dues à la présence des macromolécules intra-cristallines et extra-cristallines, en complément d’études du même genre réalisées sur des échantillons broyés. Dans les échantillons synthétiques obtenus par une méthode de synthèse simple, nous avons analysé l’effet de l’ajout d’acide polyacrylique, en termes de modulateur de croissance des polymorphes de CaCO3. La simulation des digrammes de diffraction anisotropes réalisée sur ces deux types d’échantillons nous a permis d’accéder aux informations pertinentes de façon précise (tailles anisotropes des cristallites, structure, texture, proportion volumique des polymorphes)The tremendous development of powder diffraction techniques achieved over the last ten years even operational on strongly textured samples within good resolutions, together with the fascinating development of individual calculating capabilities, make it possible to access precise information in reasonably short times. In this work, we apply the combined analysis based on the Rietveld method to study samples of natural calcium carbonates from two living species of molluscan shells and of synthetic CaCO3 in order to understand the influence of the different parameters in the growth and shape of the crystallites of the different polymorphs of CaCO3. In natural species we clearly put into evidence the existence of distortions of crystalline cells due to the presence of the intra- and extra-crystalline macromolecules, in opposition with similar studies operated on powderised samples. In synthetic samples we studied, using a simple synthesis method and taking as a model the polyacrylic acid, the role of the soluble macromolecules in the growth of the CaCO3 polymorphs. The simulation of the anisotropic diffraction diagrams on both sample types allowed us to reach pertaining information within good precision (anisotropic sizes of the crystallites, structure, texture, volume fraction of the polymorphs
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Ramos, Ana Paula. "Modificação de superfícies metálicas por meio da deposição de filmes finos orgânicos LB/LbL e filmes híbridos contendo CaCO3". Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-11092009-114534/.
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Muitos organismos vivos, tal como seus constituintes, são formados por sistemas químicos complexos que envolvem a interação entre compostos orgânicos e inorgânicos ligados química e/ou fisicamente. Nestes sistemas as matrizes orgânicas são geralmente compostas por macromoléculas como polissacarídeos e proteínas. Essas moléculas têm o papel de direcionar a nucleação e o crescimento da porção inorgânica. O uso de superfícies metálicas adequadas recobertas por este tipo de filme híbrido tem potencial aplicação em implantes de substituição óssea, no qual são requeridas superfícies quimicamente inertes, mas que ao mesmo tempo estimulem processos de calcificação. Nesta tese estudou-se o crescimento de CaCO3 sobre superfícies metálicas de alumínio e aço inox recobertas por matrizes orgânicas compostas por diferentes poliânions e pelo policátion quitosana, na forma de filmes montados camada-a-camada (do inglês LbL), na presença ou não de fosfolipídeos (filmes Langmuir-Blodgett), formando um meio confinado para o crescimento do mineral. Diferentes técnicas foram utilizadas: microscopia eletrônica, microscopia de força atômica, espectroscopias de reflexão nas regiões do Uv-vis, e do infravermelho, Raman, espalhamento e difração de raios-X. Estudou-se a influência de diferentes grupos carregados dos fosfolipídeos e dos poliânions, tal como sua conformação, no crescimento de CaCO3. O tipo de interação entre o poliânion e a quitosana leva ao crescimento de matrizes poliméricas com diferenças em suas espessuras e capacidade de retenção de líquido, modificando as condições de supersaturação local e influenciando no tipo de estrutura de CaCO3. Puderam ser identificados dois polimorfos formados sobre os filmes orgânicos de poli(ácido acrílico) e quitosana, sugerindo que existem dois diferentes sítios onde a nucleação pode ser iniciada: a partir da solução de CaCl2 aprisionada na matriz polimérica e o outro a partir dos íons cálcio ligados como contra-íons aos grupos negativamente carregados do poliânion. Na presença do pré-recobrimento LB, a natureza da cabeça polar do fosfolipídeo direciona o tipo de ligação e crescimento da matriz polimérica, que levam ao crescimento de partículas de CaCO3 com morfologia e tamanho variados, explicados em termos da presença de ambientes com diferenças de concentrações locais de Ca2+. Além disso, verificou-se que a rugosidade superficial dos suportes metálicos pode favorecer a formação do polimorfo de CaCO3 cineticamente mais estável, mostrando que o processo de cristalização sobre estes suportes é um processo governado por difusão. A hidrofilicidade dos suportes é aumentada pela presença da matriz orgânica e pela presença de CaCO3 sobre as matrizes. O crescimento de CaCO3 em meios confinados tridimensionais, formados por membranas de policarbonato modificadas com filme finos de polieletrólitos, também foi estudado. Este tipo de molde leva à formação de estruturas cilíndricas que seguem a morfologia dos poros da membrana. A presença de poli(ácido acrílico) leva a formação de estruturas cilíndricas ocas, enquanto que cilindros completamente preenchidos foram formados nos poros contendo quitosana na última camada. Estes resultados foram explicados com base em diferenças na etapa de nucleação: na presença de PAA a nucleação de CaCO3 deve iniciar-se a partir dos íons Ca2+ ligados ao poliânion que, por sua vez, está ligado diretamente às paredes do molde; já na presença que quitosana, com maior capacidade de retenção de liquido e sem interação específica com Ca2+ a nucleação e seqüente cristalização devem ocorrer por todo o poro da membrana. As estruturas formadas são em sua maioria monocristais de calcita hexagonal orientadas na direção cristalográfica <2 -2 1>.Some living organisms as well as their constituents are formed by complex chemical systems which involves the interaction among organic and inorganic compounds bounded physically or chemically. In these systems the organic matrices are usually composed by macromolecules like polysaccharides and proteins. These molecules have an important hole in tailoring the nucleation and the sequent growth of the inorganic portion. Metallic surfaces coated with these hybrid films have potential application as implants for bone substitution for which the surfaces must be chemically inert but at the same time they should stimulate calcification processes. In this present thesis we studied the growth of CaCO3 over aluminium and stainless steal surfaces coated with layer-by-layer films composed by different polyanions and chitosan as polycation, in the presence or not of phospholipids (Langmuir-Blodgett films). These organic matrices formed a confined medium within which CaCO3 particles were growth. Different techniques were applied in order to understand these systems: electronic microscopy, atomic force microscopy, UV-Vis and infrared reflection spectroscopy, Raman, and X-ray scattering and diffraction. We studied the influence of the different charged groups of the phospholipids and the polyanion as well as their conformation on CaCO3 growth. The type of interaction between the polycation and the polyanions tailors the growth of the organic matrices, forming films with different thickness and different water retention abilities which change the local supersaturation conditions changing the structure of the CaCO3 formed. Two types of CaCO3 polymorphs were growth over poly(acrylic acid) (PAA) and chitosan films suggesting that there are two sites where the nucleation can be started: the CaCl2 solution retained in the gel-like organic films and the Ca2+ ions bounded to the negative groups of the polyanion. In the presence of the LB pre-coating, the nature of the phospholipid polar head tailors the binding and the growth of the polymeric matrices leading to the formation of CaCO3 particles with difference in their sizes and morphologies. This result was explained in basis of the differences in the Ca2+ local concentrations in each situation. Moreover, it was observed that the surface roughness of the supports can favour the formation of vaterite, the kinetically most stable CaCO3 polymorph, showing that the crystallization may be guided by diffusion processes. The hidrophilicity of the supports was improved by the presence of both organic and hybrid films. The growth of CaCO3 in tridimentional confined mediums was done using LbL modified polycarbonate membranes as template. This template leads to the formation of cylindrical CaCO3 particles following the morphology of the membrane pores. CaCO3 tube-like structures were formed in presence of PAA, while rod-like structures were formed in presence of chitosan in the top LbL layer. These results were explained on basis of the difference in the nucleation stages: in the presence of PAA the nucleation starts on the Ca2+ ions bounded to the polyanion that is linked to the walls of the template; in the presence of chitosan that presents higher water retention ability and has no specific interaction with Ca2+ ions, the nucleation and sequent crystallization should occur through the entire pore of the membrane. The electron diffraction patterns showed that the CaCO3 structures are single crystals of the calcite polymorph oriented in < 2 -2 1> crystallographic direction.
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Tu, Zhenghuan. "Filtration dynamique de suspensions de CaCO3 et de solutions de surfactants". Compiègne, 2009. http://www.theses.fr/2009COMP1810.
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Ce mémoire décrit des essais de la micro et l'ultrafiltration dynamique effectués avec trois pilotes de laboratoire, un pilote MSD à disque membranaire rotatif sur deux arbres, un pilote à disque rotatif avec une membrane organique fixe, et un pilote à cylindre tournant avec une membrane concentrique. Le module MSD a été testé en microfiltration de suspensions de CaCO3 où nous avons comparé des membranes céramiques et organiques. Les essais ont confirmé l'importance du recouvrement des disques. Ensuite, nous avons appliqué le système de MSD aux traitements des effluents modèles de surfactants anioniques (solutions de SDBS et SDS), avec une comparaison au système à disque rotatif, qui permettait une pression plus élevée de fonctionnement. En terme de flux de perméat et de taux de rétention, ces deux systèmes possèdent des avantages par rapport aux systèmes de filtration tangentielle classique. Puis, les modules à disque rotatif et à cylindre tournant ont été employés à l'ultrafiltration des solutions d'albumine bovine (BSA) pour simuler l'hémofiltration (traitement de l'insuffisance rénale aiguë)This thesis focuses on dynamic micro and ultrafiltration conducted on three laboratory pilots, one with rotating membrane disks mounted on two shafts (MSD), one with a disk rotating close to a static organic membrane, and one with a cylinder rotating inside a concentric membrane. The MSD module was first used for ultrafiltration of CaCO3 suspensions, and in these tests ceramic and organic membranes were compared. The results confirmed the importance of disk overlapping in this module. Then, the MSD system was applied to the treatment of model wastewater containing anionic surfactants (SDBS and SDS solutions), and compared with the rotating disk system, which permitted a higher operating pressure. These two dynamic filtration systems present advantages compared to crossflow filtration systems, in terms of the permeate flux and membrane retention. In addition, the rotating disk and the rotating cylinder modules were used for ultrafiltration of bovine serum albumin (BSA) solutions to simulate hemofiltration in the treatment of acute renal failure
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Vieira, Juliana Aparecida. "Biodeposição de CaCO3 em materiais cimentícios : contribuição ao estudo da biomineralização induzida por Bacillus subtilis". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/170983.
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A indústria da construção civil é conhecida como umas das atividades econômicas que causam os maiores impactos ambientais desde o processo de extração da matéria prima até a produção dos produtos, incluindo o transporte e manutenção do ambiente construído. A produção de um dos seus principais componentes, o cimento, é o maior contribuinte para a emissão de gases de efeito estufa, principalmente devido a queima de combustíveis fósseis. Por este motivo, pesquisas na área de biotecnologia sustentável são conduzidas para diminuir e até mitigar os efeitos danosos provocados pelos fatores que compõem a construção civil. Dentre estas pesquisas destacam-se as que se baseiam na Biomimética, que é uma ciência que busca na Natureza as soluções tecnológicas para os problemas que os desenvolvimentos humanos geralmente apresentam: a geração de resíduos poluentes, uso de produtos químicos tóxicos e processos que operam com energia e pressão elevadas. Com base nos conceitos biomiméticos, este trabalho se propôs a estudar a biomineralização, que é um processo que ocorre na Natureza a milhares de anos e é responsável pela formação de muitas estruturas biomineralizadas tanto no ambiente terrestre como aquático. A biomineralização é um fenômeno provocado pela ação de diversas espécies de microrganismos que durante o processo de obtenção de energia reciclam minerais presentes no solo e na água e os precipitam na forma de sais inorgânicos. Este material precipitado age como agente ligante de partículas como no caso de formações geológicas (estromatólitos) ou exoesqueletos de animais marinhos, por exemplo. Neste estudo foi avaliado a biomineralização por biodeposição de carbonato de cálcio precipitado na presença da espécie de bactéria ureolítica (Bacillus subtilis) em ensaios em escala laboratorial utilizando corpos de prova de areia, argamassa e concreto. Os corpos de prova em areia e argamassa foram observados em MEV e EDS permitindo a identificação de células de microrganismos, formação de biofilme e provável formação de cristais de carbonato de cálcio na região de biofilme. Os corpos de prova de concreto foram utilizados para avaliar as consequências da biodeposição na absorção de água por capilaridade do material. Resultados indicam redução de 20% na absorção de água por capilaridade. Com os resultados obtidos é possível concluir que a técnica de biodeposição pode ser uma alternativa ao tratamento superficial de estruturas de concreto, contudo requer estudos posteriores de aplicação técnica e viabilidade econômica.The construction industry has been known as one of the economic activities that cause the major environment impacts since the process of raw material extraction until the products manufacturing including transport and maintenance of the built environment. The production of one of the main compounds, the cement, is the largest contributor to the greenhouse gas emissions, mainly due to burn fossil fuels. For this reason, researches in sustainable biotechnological area are conducted to minimize and even mitigate the damaging effects either promoted by construction industry factors. Among these ones, it stands out researches based on Biomimetic, which is a science that seeks in Nature the technological solutions for problems that human’s development usually presents: the generation of pollutant residues, the use of toxic chemicals and process that operates in high pressure and energy. Based on biomimetic concepts this research proposes to study the biomineralization, which is a process that has occurred in the Nature for thousands of years and it is responsible for the formation of many structures either in soil and water environments. The biomineralization is a phenomenon caused by several specimens of microorganisms that during the process of obtaining energy, they recycle minerals presents at soil and water inducing precipitation as inorganic salts. This precipitated material works as a binder of particles similar to geologic formations (stromatolites) or exoskeleton of sea animal for example. In this study the biomineralization was evaluated through biodeposition of precipitated calcium carbonate by specimen of ureolytic bacteria (Bacillus subtilis). Essays were held using samples made by sand, mortar and concrete. The samples made by sand and mortar were observed at MEV and EDS, allowing the identification of microorganism cells, biofilm formation and probable formation of calcium carbonate crystals at biofilm region. The concrete samples were used to evaluate the consequences of biodeposition on water absorption by capillarity of the material. The results show reduction of 20% on water absorption by capillarity. According the results achieved it possible to conclude that the biodeposition technique can be an alternative to superficial treatment for concrete structures. However, it will be required more studies to evaluate technical application and economical availability.
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Matahwa, Howard. "Chemical modification of polysaccharides with hydrophilic polymers for CaCO3 crystal growth modification and filler retention, for paper applications". Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/1396.
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Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008.Polysaccharides were modified with selected polymers via the grafting technique. Both anionic and cationic polysaccharides were prepared. Random and crosslinked graft copolymers were also prepared. The percentage grafting was determined by gravimetric analysis and results were confirmed by cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance microscopy (CP/MAS 13C NMR). These modified biodegradable polymers were then used to flocculate precipitated calcium carbonate (PCC). The effects of pH, percentage grafting, crosslinker concentration and polysaccharide concentration on PCC flocculation were evaluated. Furthermore, the effects of anionic and cationic starch, either added to PCC sequentially or simultaneously, on PCC flocculation were also investigated. Generally, anionically modified starch showed excellent flocculation properties, which are desirable for the end application of PCC retention. The effect of polyacrylic acid (PAA) and polyacrylamide (PAM) modified cellulose fibers on calcium carbonate crystal nucleation and growth modification was investigated. When the heterogeneous crystallization of CaCO3 was carried out in the presence of modified cellulose fibers the CaCO3 crystals were found to be residing on the surface of the fibers. The morphologies of the crystallized CaCO3, polymorph and fiber surface coverage were different for cellulose materials grafted with polymers of different functionalities, meaning that there is interaction between the crystal growth modifier and the growing nuclei. The effect of the modified starch on the crystallization of calcium carbonate gave useful insight into designing CaCO3 filler morphologies. It was found that the filler size, morphology and surface properties of fillers can be tailor-made by choosing suitable CaCO3 crystallization conditions as well as a suitable crystal growth modifier. The crystallized CaCO3 had a negatively charged surface. Results of fluorescence studies showed that the PAA modified starch (polymeric additive used) resided on the surface of the crystals. Thus the presence of the polysaccharide on the surface of a filler could be advantageous for strengthening fiber–filler bonding in paper applications. Anionic starch materials were also used to prepare anionic-starch-coated starch particles. Both the anionic starch and anionic-starch-coated starch particles were evaluated for PCC retention and other properties of hand sheets. When anionic-starch-coated starch particles were used there was generally an improvement in the PCC retention, while the other paper properties remained desirable. The success achieved with the use of anionic-starch-coated starch particles now opens the way for the further preparation and testing of various modified starch particles, for optimization of filler retention.
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Görgen, Sigrid. "Les mécanismes moléculaires de la biominéralisation intracellulaire de CaCO3 chez les cyanobactéries". Electronic Thesis or Diss., Sorbonne université, 2020. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2020SORUS158.pdf.
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La biominéralisation des carbonates de calcium est un processus répandu chez les bactéries. Cependant les mécanismes moléculaires sous-jacents restent mal compris. Récemment, la biominéralisation intracellulaire de phases amorphes de carbonate de calcium (iACC) a été découverte chez des cyanobactéries répandues environnementalement et phylogénétiquement. Un gène orphelin de fonction inconnue, nommé ccyA et codant pour une protéine nommée Calcyanine, a été identifié uniquement chez ces cyanobactéries. Ainsi mon travail de thèse a consisté à développer une approche génétique pour analyser la fonction in vivo du gène ccyA et déterminer si la protéine qu’il code est impliquée ou non dans la formation des iACC. L’échec des tentatives de délétion de ccyA chez Cyanothece sp. PCC 7425 et Synechococcus sp. PCC 6312 suggère que ce gène leur est essentiel. Nous avons donc construit une expression hétérologue de ccyA dans des cyanobactéries modèles ne formant pas naturellement des iACC. L’expression constitutive de diverses séquences du gène ccyA a montré que la croissance de Synechococcus elongatus PCC 7942 est ralentie par rapport à celle de la souche sauvage. En accord, les mutants exprimant le ccyA présentent plus de cellules mortes que la souche sauvage. Enfin, ces mutants possèdent plus de calcium intracellulaire que la souche sauvage, suggérant une modification de l’homéostasie du calcium. Enfin, j’ai introduit des plasmides par conjugaison chez Cyanothece sp. PCC 7425 et Synechococcus sp. PCC 6312 leur permettant de surproduire ccyA. La Calcyanine fusionnée avec la eGFP se localise à la membrane et aux pôles des cellules chez la souche Synechococcus sp. PCC 6312The biomineralization of calcium carbonates is a common process in bacteria, however, the underlying molecular mechanisms remain poorly understood. Recently, intracellular biomineralization of amorphous calcium carbonate phases (iACC) has been discovered in environmentally and phylogenetically widespread cyanobacteria. An orphan gene of unknown function, named ccyA and coding for a protein named Calcyanin, has been identified only in these cyanobacteria. My thesis work consisted in developing a genetic approach to analyze the in vivo function of the ccyA gene and determine whether or not the encoded protein is involved in the formation of iACCs. The failure of ccyA deletion attempts in Cyanothece sp. PCC 7425 and Synechococcus sp. PCC 6312 suggests that this gene could be essential to cells viability. We have therefore introduced a plasmid allowing heterologous expression of ccyA in model cyanobacteria that do not naturally form iACC. The constitutive expression of various ccyA sequences in Synechococcus elongatus PCC 7942 is slowed down compared to that of the wild strain. In agreement, ccyA-expressing mutants have more dead cells than the wild-type strain. Finally, these mutants have more intracellular calcium than the wild strain, suggesting a modification of calcium homeostasis. Finally, I introduced plasmids by conjugation in Cyanothece sp. PCC 7425 and Synechococcus sp. PCC 6312 allowing them to overproduce ccyA. Calcyanin fused with eGFP is localized to the membrane and poles of cells in Synechococcus sp. PCC 6312
Libros sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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The 2006-2011 World Outlook for Precipitated Calcium Carbonate (100 Percent CaCO3). Icon Group International, Inc., 2005.
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Parker, Philip M. The 2007-2012 World Outlook for Precipitated Calcium Carbonate (100 Percent CaCO3). ICON Group International, Inc., 2006.
Buscar texto completoCapítulos de libros sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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Siakotos, M., N. Tsianas, J. Malegos, G. Metaxatos, M. Zavros, P. Magana, G. Stavianoudakis, D. Georgakopoulou, AL Gerakis y A. Billis. "Calcium Carbonate (CaCO3) as a Phosphate Binder in Patients on Renal Replacement Therapy". En New Therapeutic Strategies in Nephrology, 338–45. Boston, MA: Springer US, 1991. http://dx.doi.org/10.1007/978-1-4615-3884-4_100.
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Haugen, Malin, Bergit Brattekås y Martin Fernø. "Multimodal Visualization of Calcium Carbonate (CaCO3) in the Pore Space of a Micromodel". En Album of Porous Media, 95. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-23800-0_77.
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Masunaga, K. M. y T. Iyoda. "Powder wastes from concrete recycling as a sustainable source of calcium carbonate mineral admixture". En Life-Cycle of Structures and Infrastructure Systems, 3268–75. London: CRC Press, 2023. http://dx.doi.org/10.1201/9781003323020-399.
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Verrecchia, Eric P., Corinne Loisy, Olivier Braissant y Anna A. Gorbushina. "The Role of Fungal Biofilm and Networks in the Terrestrial Calcium Carbonate Cycle". En Fossil and Recent Biofilms, 363–69. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-0193-8_25.
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Zulkefli, N., M. D. Ahmad, S. Mahzan y E. M. Yusup. "The Development of Temporary Bone Scaffolds from High Density Polyethylene (HDPE) and Calcium Carbonate (CaCO3) for Biomedical Application". En Structural Integrity and Monitoring for Composite Materials, 243–59. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6282-0_15.
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Pisias, Nicklas G. y Warren L. Prell. "Changes in Calcium Carbonate Accumulation in the Equatorial Pacific During the Late Cenozoic: Evidence from HPC Site 572". En The Carbon Cycle and Atmospheric CO2 : Natural Variations Archean to Present, 443–54. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm032p0443.
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Tapas, M. J., A. Yan, P. Thomas, C. Holt y V. Sirivivatnanon. "Effect of Carbonation on the Microstructure and Phase Development of High-Slag Binders". En Lecture Notes in Civil Engineering, 213–21. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_22.
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AbstractThe drive for sustainable concrete production favors the use of high replacement levels of supplementary cementitious materials (SCMs) in the concrete mix. The use of SCMs such as fly ash and slag, however, although they improve the sustainability of concrete production as well as most concrete durability properties, increases the carbonation rate. Carbonation decreases the pH of the concrete pore solution, making the steel reinforcement susceptible to corrosion. The effect of carbonation is, however, not confined to the change in pH of the pore solution. We investigated changes in the microstructure and phases of high-slag binders due to carbonation. The carbonation resistance of mortars with 50 and 70% slag replacement were investigated at exposure conditions of 2%CO2, 50%RH, 23 °C. The carbonated and non-carbonated parts of the mortars were subjected to various characterization techniques to investigate the effect of carbonation on microstructure and phase development. Results confirmed the absence of portlandite in all the carbonated regions (“colorless” by phenolphthalein test, which indicated that the change in color of the phenolphthalein solution was due to the absence of portlandite to buffer the pH). Significant reduction in the amount of C-S-H, as well as increase in the amount of calcium carbonate, were been observed in the carbonated regions. Aragonite, a polymorph of CaCO3, was very prominent in all the carbonated mortars.
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Tropf, William J. "Calcium Carbonate, Calcite (CaCO3)". En Handbook of Optical Constants of Solids, 701–15. Elsevier, 1997. http://dx.doi.org/10.1016/b978-012544415-6.50126-6.
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"Calcium Carbonate Cycle". En Ocean Biogeochemical Dynamics, 359–91. Princeton University Press, 2013. http://dx.doi.org/10.2307/j.ctt3fgxqx.13.
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"Chapter 9: Calcium Carbonate Cycle". En Ocean Biogeochemical Dynamics, 359–91. Princeton University Press, 2006. http://dx.doi.org/10.1515/9781400849079-010.
Texto completoActas de conferencias sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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Ness, Giulia, Ken Stuart Sorbie, Ali Hassan Al Mesmari y Shehadeh Masalmeh. "The Impact of CCUS for Improved Oil Recovery on CaCO3 Scaling Potential of Produced Fluids". En SPE EuropEC - Europe Energy Conference featured at the 83rd EAGE Annual Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209676-ms.
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Abstract Unlike other CCUS technologies, CO2 EOR has been widely implemented at a commercial level and on an industrial scale. In CO2 EOR, CO2 can be injected on its own or alternated with water in CO2 WAG (water-alternating-gas). Both applications have a direct impact on produced fluid compositions influencing GOR, water cut, CO2 concentration and consequently Ca2+, alkalinity and pH. The variation of fluid compositions has an inevitable impact on the scaling potential of produced fluids and on the resulting level of scale formation and its mitigation strategy. The aim of this work is to investigate the scaling potential changes for a wide range of CO2 WAG scenarios in a high salinity carbonate reservoir in the Middle East using input data from reservoir modelling simulations and running multiple sensitivity studies. The main scale formed in this reservoir is calcium carbonate (CaCO3). The equilibrium reservoir water, the produced water chemistry profiles from downhole to stock tank and the scaling risk profiles are modelled using a commercial integrated PVT and aqueous phase software. A rigorous scale prediction procedure previously published by the authors is applied to accurately calculate scale risk trends for variable production scenarios. As CO2 increases in the WAG cycle, reservoir pH drops but the equilibrium with CaCO3 rock causes an increase in alkalinity. This results in more CaCO3 precipitation in the production system where pressure drops and CO2 flashes off solution. Hence, these results show unequivocal detrimental impact of CO2 WAG on the calcium carbonate scaling potential of produced fluids. This leads to a need for operational and/or chemical adjustments to the scale management program when this technology is deployed. Whilst in this field some CaCO3 scale is predicted to form downhole, but this is not a severe problem although it may need to be addressed. The separator is operated at a sufficiently high pressure that calcium carbonate is not expected to form there. Changing operating pressures and CO2 and H2S concentrations can shift some of the problem to the separator, but if this remains at high pressure there will be no scale precipitation here. However, the calcium carbonate scale will predominantly precipitate at stock tank conditions. Implementing green technologies such CCUS is fundamental to achieving net zero goals and this work clearly shows that actions need to be taken to manage the associated CaCO3 scale problems in the produced fluids to make this application successful.
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Hu, Shengfei, Wen Chen y Huaxing Li. "Preparation and Properties of Nano-Calcium Carbonate Modified PVC Using Ultrasonic Irradiation". En 2007 First International Conference on Integration and Commercialization of Micro and Nanosystems. ASMEDC, 2007. http://dx.doi.org/10.1115/mnc2007-21449.
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PVC/nano-CaCO3 composites were prepared through ultrasonic irradiation. The optimum time of ultrasonic irradiation is 30 min. The fracture toughness of the nanocomposites was investigated by J-integral method based on the mechanical properties and morphology. Compared with corresponding nanocomposites and unfilled PVC, the prepared nanocomposites exhibit outstanding mechanical performances. The mechanical properties of spindly shaped CaCO3 filled PVC are better than these of the cubic nano-CaCO3, which are likely attributed to high aspect ratio of spindly shaped nano-CaCO3. In addition, the mechanical properties of PVC/nano-CaCO3 composites can be improved considerably when the content of nano-CaCO3 is 5–15 phr. Ultrasonic irradiation realizes the excellent dispersion of nanoparticles in the PVC, and offers a new way to deal with the challenges encountered in preparing polymer/nanocomposites materials.
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Mavredaki, Eleftheria y Anne Neville. "Prediction and Evaluation of Calcium Carbonate Deposition at Surfaces". En SPE International Oilfield Scale Conference and Exhibition. SPE, 2014. http://dx.doi.org/10.2118/spe-169796-ms.
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Abstract Mineral scaling is one of the main flow assurance problems facing the oil and gas sector and imposes severe constraints on the economic and safe operation of many fields. During the last decades, operators, in conjunction with the chemical manufacturers and oilfield service companies have focused on understanding, predicting and mitigating scale formation. Even though progress towards better management of scale formation continues, scale precipitation is still a significant flow assurance problem, caused by changes in temperature and pressure conditions or by mixing incompatible waters (produced water, seawater, aquifers) especially at high water cuts. One of the most frequently depositing scale types in the oil production process is calcium carbonate. To date, the overwhelming amount of research has been on the thermodynamics that drive the precipitation of calcium carbonate in an aqueous system, with little attention given to actual surface deposition. Therefore, to improve scale management practices, the kinetics that dominate CaCO3 surface formation need to be understood. The work presented in this paper, has as its main focus the deposition of CaCO3 at a stainless steel surface. The data from the surface is presented in conjunction with the findings from bulk phase experiments. A small bore flow rig and a quartz crystal microbalance were used for monitoring the induction time and the real time deposition of CaCO3. Calcium carbonate deposition was examined at a range of conditions with emphasis given to different saturation ratios (SR). The results are discussed in correlation with the theoretical calculations based on a scale prediction software. The data collected from the CaCO3 surface experiments contribute to understanding at which level the saturation ratio becomes a threat with respect to scale formation at surfaces. This paper describes steps towards predicting the induction time of calcium carbonate at surfaces, when the main input is the saturation ratio.
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Mohamed, Julie Juliewatty, Nurul Ainon Bakar, Siti Mariam Mat Nor, Muhammad Azwadi Sulaiman, Pao Ter Teo, Norfadhilah Ibrahim, Akhmad Herman Yuwono y Mohd Fariz Ab Rahman. "Calcium carbonate (CaCO3) contents influence the properties of mambong clay". En INTERNATIONAL CONFERENCE ON BIOENGINEERING AND TECHNOLOGY (IConBET2021). AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0078980.
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Ahab, Atika, Yulin Dayanti, Since Bausele, Nina Siti Aminah y Ikah Ning Prasetiowati. "Analysis of calcium carbonate (CaCO3) particles from Achatina fulica shells". En II INTERNATIONAL CONFERENCE “SUSTAINABLE DEVELOPMENT: AGRICULTURE, VETERINARY MEDICINE AND ECOLOGY”. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0130940.
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Zou, Yong, Liang Zhao, Gongming Xin y Lin Cheng. "Effect of Metallic Ion on the Formation of Calcium Carbonate Fouling". En 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22312.
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Calcium carbonate (CaCO3) is the most common fouling adhering on the surface of heat exchanger. But metallic ion in natural water could affect the crystalline type of calcium carbonate. In this study, the effect of sodium ion, magnesium ion and aluminum ion on crystalline type and morphology of CaCO3 were reported. The experimental results indicate that the addition of sodium ion has no obvious role for changing the crystalline type of CaCO3, only calcite was obtained and the lattice parameter of calcite has a little variation depending on the concentration of sodium ion. However, the addition of magnesium and aluminum ion prompts obviously the formation of aragonite. In order to clarify the mechanism about the effect of metallic ion on lattice stability of calcium carbonate, the energies and electronic structures for the calcite with sodium, magnesium or aluminum inclusion have been determined from first-principle calculations. The calculated results indicate magnesium and aluminum inclusion has more effects on the stability of calcite than that of sodium inclusion.
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Agofack, Nicolaine, Hoang Nguyen Hoang, Pierre Cerasi, Anna Stroisz y Marcel Naumann. "Effect of Supercritical CO2 and Thermal Loading Cycles on Class G Well Cement Properties". En 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0439.
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ABSTRACT In carbon dioxide (CO2) capture and storage (CCS) technology, one of the goals is to prevent the injected CO2 from leaking back into the atmosphere. The leakage paths include fractures on the cement sheath sealing the injection well and/or reactivated faults going through the caprock. During a batch-wise injection of CO2, the wellbore is submitted to thermal loading cycles. After injection, the near-well materials, including cement sheath, are exposed to a CO2-rich environment, especially in the vicinity of the reservoir. These thermal cycles (TC) and exposure environment can affect the properties of the sealing material like cement and create leakage paths. Portland G cement samples were submitted to TC and exposed to a supercritical CO2 environment, respectively. The results show that after submitting to more than 100 TC, the strength of the cement sample can decrease by 40% and its Young's modulus by 20%. On the other hand, after exposure to supercritical CO2 for 52 days, the strength of the cement can increase up to 170% and its Young's modulus up to 25%, depending on the cement slurry formulation. INTRODUCTION Cement paste in CCS wells can experience different mechanical and thermal loadings. During hydration, the cement pastes are also exposed to various temperature conditions. After well construction, when cement hydration takes place, the cured cement is submitted to thermal cyclic loadings following a batchwise CO2 injection. Injected from the seabed at a 4°C, the CO2, while going down along the well into the reservoir, cooldown the wellbore and its surroundings to a temperature much lower than the in-situ one. During maintenance or when shifting from one batch to another, the wellbore temperature will raise again towards its initial in-situ value. These thermal loadings can significantly affect the properties of the cement sheath, compromise its integrity by creating leakage paths for the stored CO2 to escape the reservoir. Previous investigations have shown that properties of cement and cement-sand mixture are highly affected when exposed to high temperatures (Cao et al., 2022; Dillenbeck et al., 2002; Milestone et al., 2012; Mindeguia et al., 2010; Peng & Huang, 2008; Rimmelé et al., 2008; Urbonas et al., 2016; Vu, 2013; Zeng et al., 2022). In the case of a leakage path in the cement sheath, remedy solutions include squeeze cementing operations. This consists of performing a perforation to the casing and squeezing cement slurry to seal the leakage paths (Manceau et al., 2014; Todorovic et al., 2016). For remediation of CO2 leakage, part of the squeezed cement slurry may be hydrated while exposed to CO2. A CO2-rich environment is expected to influence the properties of the hydrating cement. Some publications indicate that cement carbonation increases with relative humidity (RH) (Hunt et al., 1958). It is very slow for RH lower than 25% and highly enhanced for RH higher than 90%. The same authors demonstrate a smaller amount of non-evaporable water after hydration accompanied by CO2 exposure for more carbonated cement. According to Fabbri et al. (2009), Johannesson & Utgenannt (2001) and Milestone et al. (2012), the mechanism of carbonation is a chemical reaction of calcium hydroxide and calcium silicate hydrates with CO2. Calcium ions (Ca2+) migrate through a saturated porous medium, leaving a leached zone and then rapidly precipitate as calcium carbonate (CaCO3) when meeting the dissolved CO2 (Fabbri et al., 2009; Johannesson & Utgenannt, 2001; Milestone et al., 2012). After exposing hardened cement and mortar samples to scCO2 for only four hours, significant strength increase and porosity reduction were observed (Urbonas et al., 2016). According to these authors, these changes result from carbonation which leads to microstructure change. Dillenbeck et al. (2002) showed that the carbonation depth is higher in ordinary Portland cement (OPC) with fly-ash (FA/OPC) than in OPC alone. In both cement systems, it increases with the exposure time. Consequently, the compressive strength of OPC cement increased after exposure to CO2 for up to 6 months and then decreased afterwards (Dillenbeck et al., 2002). After exposing Portland cement G to wet CO2 and CO2-saturated water under the pressure of 280 bars and temperature of 90°C, Rimmelé et al. (2008) measured a reduction in the porosity after 3 weeks (resp. 6 weeks) of exposure to CO2-saturated water (resp. wet CO2). Eventually, the porosity increased to a final value, lower than the reference one, after 6 months of exposure. Many of these investigations are rather limited to microstructure analysis in terms of mineral changes or compressive strength. The stiffness of the material, as well as the dynamic properties, are rarely investigated. In this campaign, different cement formulations, hydrated under different conditions and subjected to many thermal loading cycles are tested. Compressive strength, porosity, stiffness and density change after scCO2 exposure and temperature treatment were measured.
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Liu, Zilong, Hayati Onay, Fengzhi Guo y Pegah Hedayati. "Electrochemically Assisted Deposition of Calcium Carbonate Surfaces for Anionic Surfactant Adsorption: Implications for Enhanced Oil Recovery". En SPE International Conference on Oilfield Chemistry. SPE, 2021. http://dx.doi.org/10.2118/204283-ms.
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Abstract Surface roughness of rocks had a significant influence on surfactant adsorption in enhanced oil recovery (EOR), both in terms of the total amount adsorbed as well as of the kinetics of adsorption. Combining electrochemical techniques and quartz crystal microbalance with dissipation monitoring (QCM) into one analysis setup opens up new avenues for depositing model rock surfaces and investigating the adsorption behavior. Using electrochemically assisted deposition, uniform and well-covered metal-CaCO3 sensors were obtained to simulate rough carbonate rocks and characterized by scanning electron microscope with energy dispersive X-ray analysis (SEM-EDX). The deposition process was controlled by the nitrate and oxygen electroreduction reactions in the presence of bicarbonate and calcium ions. The deposited mass of CaCO3 was calculated and the coverages for Au-CaCO3 and Pt-CaCO3 sensors were between 20 - 60%. It is observed that mostly cubic-like CaCO3 crystals were formed with crystal sizes around 20 to 50 µm from the SEM micrographs. The bigger crystals were surrounded by bare regions of Pt surface, suggesting the existence of Ostwald ripening process. Prior to the investigation of the deposited CaCO3 surfaces, the adsorption of anionic surfactant alcohol alkoxy sulfate (AAS) was studied on a smooth commercial CaCO3 surface with varying pH and CaCl2concentrations using QCM. Subsequently, surfactant adsorption was performed on the rough deposited CaCO3 surfaces and their adsorption behavior were compared. On a smooth CaCO3 surface, a fast adsorption of AAS surfactant was observed, whereas the desorption process was characterized as a two-step process. Compared to the smooth CaCO3surface, an increase of the frequency shift of about 5 times was observed on the deposited CaCO3 surfaces. This observation was mainly ascribed to the rougher surfaces, having more adsorption sites for AAS binding, and also the liquid trapping effect, resulting in more frequency shifts. It is suggested that a rough model mineral surface could be a better representation of a rock surface, presenting the implications of the new understanding for surfactant adsorption on different rock surfaces in EOR.
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Langer, G., J. Kwo y D. Murano. "New Coating Solutions for Biomedical Applications". En ITSC2002, editado por C. C. Berndt y E. Lugscheider. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2002. http://dx.doi.org/10.31399/asm.cp.itsc2002p0192.
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Abstract Crystallized calcium carbonate, CaCO3, is a mineral phase that occurs in nature as aragonite. It is well known that CaCO3 shows excellent chemical interaction and intensive binding in direct contact to bone structures. This paper discusses the development of a plasma spraying process that shows promise for producing dense calcium carbonate layers with good adhesion properties. Tests reveal that the resulting coatings are fully biocompatible and have faster resorption times than plasma sprayed hydroxyapatite. Paper includes a German-language abstract.
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Putro, Triswantoro y Endarko. "The influence of electron discharge and magnetic field on calcium carbonate (CaCO3) precipitation". En THE 3RD INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS SCIENCE AND TECHNOLOGY (ICAMST 2015). Author(s), 2016. http://dx.doi.org/10.1063/1.4945521.
Texto completoInformes sobre el tema "Cycle du carbonate de calcium (CaCO3)"
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Antoun, Tarabay H. y Donald R. Curran. Wave Propagation in Intact and Jointed Calcium Carbonate (CaCO3) Rock. Fort Belvoir, VA: Defense Technical Information Center, marzo de 1996. http://dx.doi.org/10.21236/ada305457.
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