Science.gov

Sample records for calcitic hydrated lime

  1. Removal of phosphate from greenhouse wastewater using hydrated lime.

    PubMed

    Dunets, C Siobhan; Zheng, Youbin

    2014-01-01

    Phosphate (P) contamination in nutrient-laden wastewater is currently a major topic of discussion in the North American greenhouse industry. Precipitation of P as calcium phosphate minerals using hydrated lime could provide a simple, inexpensive method for retrieval. A combination of batch experiments and chemical equilibrium modelling was used to confirm the viability of this P removal method and determine lime addition rates and pH requirements for greenhouse wastewater of varying nutrient compositions. Lime: P ratio (molar ratio of CaMg(OH)₄: PO₄‒P) provided a consistent parameter for estimating lime addition requirements regardless of initial P concentration, with a ratio of 1.5 providing around 99% removal of dissolved P. Optimal P removal occurred when lime addition increased the pH from 8.6 to 9.0, suggesting that pH monitoring during the P removal process could provide a simple method for ensuring consistent adherence to P removal standards. A Visual MINTEQ model, validated using experimental data, provided a means of predicting lime addition and pH requirements as influenced by changes in other parameters of the lime-wastewater system (e.g. calcium concentration, temperature, and initial wastewater pH). Hydrated lime addition did not contribute to the removal of macronutrient elements such as nitrate and ammonium, but did decrease the concentration of some micronutrients. This study provides basic guidance for greenhouse operators to use hydrated lime for phosphate removal from greenhouse wastewater.

  2. SUBGRADE STABILIZATION WITH PORTLAND CEMENT AND HYDRATED LIME UNDER MODIFIED T11 LANDING MAT.

    DTIC Science & Technology

    Sections of a low-strength subgrade (4 to 7 CBR) were treated with portland cement and hydrated lime to assist in maintaining the strength of the...It was determined that both portland cement and hydrated lime, applied as 3 percent admixtures, were effective in improving the resistance of the

  3. Hydrated lime for metals immobilization and explosives transformation: Treatability study.

    PubMed

    Martin, W Andy; Larson, S L; Nestler, C C; Fabian, G; O'Connor, G; Felt, D R

    2012-05-15

    Fragmentation grenades contain Composition B (RDX and TNT) within a steel shell casing. There is the potential for off-site migration of high explosives and metals from hand grenade training ranges by transport in surface water and subsurface transport in leachate. This treatability study used bench-scale columns and mesocosm-scale laboratory lysimeters to investigate the potential of hydrated lime as a soil amendment for in situ remediation of explosives and metals stabilization in hand grenade range soils. Compared to the unamended soil there was a 26-92% reduction of RDX in the leachate and runoff water from the lime treated soils and a 66-83% reduction of zinc in the leachate and runoff water samples; where the hand grenade range metals of concern were zinc, iron, and manganese. The amended soil was maintained at the target pH of greater than 10.5 for optimum explosives decomposition. The treatability study indicated a high potential of success for scale-up to an in situ field study.

  4. Sludge ash/hydrated lime on the geotechnical properties of soft soil.

    PubMed

    Lin, Deng-Fong; Lin, Kae-Long; Hung, Min-Jui; Luo, Huan-Lin

    2007-06-25

    In this study, an effort to improve the properties and strength of soil, sewage sludge ash (SSA) and hydrated lime are applied to stabilize soft cohesive subgrade soil. Five different ratios (in weight percentage), 0%, 2%, 4%, 8%, and 16%, of sludge ash/hydrated lime are proposed for mixture with cohesive soil. Then, the effects of the different proportions of SSA/hydrated lime on soft cohesive soil are studied. Test results indicate that the unconfined compressive strength of specimens with additives was raised from three to seven times better than that of the untreated soil, and swelling behaviors were also effectively reduced for those specimens. Results of triaxial compression test indicate that the shear strength parameter, c, rose with an increased amount of additives and improved from 30 to 50-70kPa. On the whole, SSA/hydrated lime could particularly improve the geotechnical properties of cohesive subgrade soil.

  5. The elimination of Salmonella typhimurium in sewage sludge by aerobic mesophilic stabilization and lime hydrated stabilization.

    PubMed

    Plachá, Iveta; Venglovský, Ján; Maková, Zuzana; Martinéz, José

    2008-07-01

    This study observed the effects of two methods, aerobic mesophilic stabilization and lime hydrated stabilization of sewage sludge upon the survival of Salmonella typhimurium. Raw (primary) sludges from the mechanical biological municipal sewage treatment plant were used. Aerobic stabilization and lime hydrated stabilization were carried out in a laboratory fermentor. Aerobic stabilization was carried out in the mesophilic temperature range (from 25.70+/-0.40 to 37.82+/-1.38 degrees C). Lime hydrated was used at an amount of 10 kg/m(3) for the stabilization. Sludge samples were inoculated with a broth culture of S. typhimurium. Quantitative and qualitative examinations of the presence of S. typhimurium were carried out. Aerobic mesophilic stabilization caused elimination S. typhimurium within 48 h. The T(90) value of S. typhimurium was 6.66+/-0.20 h. During the lime hydrated stabilization pH values significantly increased from 5.66+/-0.07 to 12.12+/-0.02 (P<0.01). S. typhimurium was inactivated within 1h and the T(90) value was 0.19+/-0.01 h. Our study confirmed that the treatment of sewage sludge with lime hydrated was significantly more effective than the aerobic mesophilic stabilization, (P<0.01).

  6. Advanced treatment of swine wastewater using an agent synthesized from amorphous silica and hydrated lime.

    PubMed

    Tanaka, Yasuo; Hasegawa, Teruaki; Sugimoto, Kiyomi; Miura, Keiichi; Aketo, Tsuyoshi; Minowa, Nobutaka; Toda, Masaya; Kinoshita, Katsumi; Yamashita, Takahiro; Ogino, Akifumi

    2014-01-01

    Advanced treatment using an agent synthesized from amorphous silica and hydrated lime (M-CSH-lime) was developed and applied to swine wastewater treatment. Biologically treated wastewater and M-CSH-lime (approximately 6 w/v% slurry) were fed continuously into a column-shaped reactor from its bottom. Accumulated M-CSH-lime gradually formed a bed layer. The influent permeated this layer and contacted the M-CSH-lime, and the treatment reaction progressed. Treated liquid overflowing from the top of the reactor was neutralized with CO₂gas bubbling. The colour removal rate approximately exceeded 50% with M-CSH-lime addition rates of > 0.15 w/v%. The removal rate of PO(3⁻)(4) exceeded 80% with the addition of>0.03 w/v% of M-CSH-lime. The removal rates of coliform bacteria and Escherichia coli exceeded 99.9% with > 0.1 w/v%. Accumulated M-CSH-lime in the reactor was periodically withdrawn from the upper part of the bed layer. The content of citric-acid-soluble P₂O₅ in the recovered matter was>15% when the weight ratio of influent PO(3⁻)(4) -P to added M-CSH-lime was > 0.15. This content was comparable with commercial phosphorus fertilizer. The inhibitory effect of recovered M-CSH-lime on germination and growth of leafy vegetable komatsuna (Brassica rapa var. perviridis) was evaluated by an experiment using the Neubauer's pot. The recovered M-CSH-lime had no negative effect on germination and growth. These results suggest that advanced water treatment with M-CSH-lime was effective for simultaneous removal of colour, [Formula: see text] and coliform bacteria at an addition rate of 0.03-0.15 w/v%, and that the recovered M-CSH-lime would be suitable as phosphorus fertilizer.

  7. Lime

    USGS Publications Warehouse

    Miller, M.

    2006-01-01

    In 2005, US lime production was 20 Mt with a value of $1.5 billion. Production was unchanged compared with 2004. Captive production was 1.4 Mt. US consumption was 20.2 Mt. Most of the US lime trade was with Canada and Mexico. Despite some disruptions due to hurricanes Katrina and Rita, normal sales activities remained healthy.

  8. Iron blast furnace slag/hydrated lime sorbents for flue gas desulfurization.

    PubMed

    Liu, Chiung-Fang; Shih, Shin-Min

    2004-08-15

    Sorbents prepared from iron blast furnace slag (BFS) and hydrated lime (HL) through the hydration process have been studied with the aim to evaluate their reactivities toward SO2 under the conditions prevailing in dry or semidry flue gas desulfurization processes. The BFS/HL sorbents, having large surface areas and pore volumes due to the formation of products of hydration, were highly reactive toward SO2, as compared with hydrated lime alone (0.24 in Ca utilization). The sorbent reactivity increased as the slurrying temperature and time increased and as the particle size of BFS decreased; the effects of the liquid/solid ratio and the sorbent drying conditions were negligible. The structural properties and the reactivity of sorbent were markedly affected by the BFS/HL ratio; the sorbent with 30/70 ratio had the highest 1 h utilization of Ca, 0.70, and SO2 capture, 0.45 g SO2/g sorbent. The reactivity of a sorbent was related to its initial specific surface area (Sg0) and molar content of Ca (M(-1)); the 1 h utilization of Ca increased almost linearly with increasing Sg0/M. The results of this study are useful to the preparation of BFS/HL sorbents with high reactivity for use in the dry and semidry processes to remove SO2 from the flue gas.

  9. Engineering properties of water/wastewater-treatment sludge modified by hydrated lime, fly ash and loess.

    PubMed

    Lim, Sungjin; Jeon, Wangi; Lee, Jaebok; Lee, Kwanho; Kim, Namho

    2002-10-01

    The purpose of this research was to present engineering properties of modified sludge from water/wastewater treatment by modifiers such as hydrated lime, loess, and fly ash. The proper mixing ratio was determined to hold the pH of the modified sludge above 12.0 for 2 h. Laboratory tests carried out in this research included particle analysis, compaction and CBR, SEM and X-ray diffraction, unconfined compression test, permeability test, and TCLP test. The main role of lime was to sterilize microorganisms in the sludge. The unconfined strength of the modified sludge by fly ash and loess satisfied the criteria for construction materials, which was above 100 kPa. The permeability of all the mixtures was around 1.0 x 10(-7) cm/s. Extraction tests for hazardous components in modified sludge revealed below the regulated criteria, especially for cadmium, copper, and lead. The present study suggested that the use of lime, fly ash, and loess be an another alternative to modify or stabilize water/wastewater treatment sludge as construction materials in civil engineering.

  10. Methanogenic calcite, 13C-depleted bivalve shells, and gas hydrate from a mud volcano offshore southern California

    USGS Publications Warehouse

    Hein, J.R.; Normark, W.R.; McIntyre, B.R.; Lorenson, T.D.; Powell, C.L.

    2006-01-01

    Methane and hydrogen sulfide vent from a cold seep above a shallowly buried methane hydrate in a mud volcano located 24 km offshore southern California in?? 800 m of water. Bivalves, authigenic calcite, and methane hydrate were recovered in a 2.1 m piston core. Aragonite shells of two bivalve species are unusually depleted in 13C (to -91??? ??13C), the most 13C-depleted shells of marine macrofauna yet discovered. Carbon isotopes for both living and dead specimens indicate that they used, in part, carbon derived from anaerobically oxidized methane to construct their shells. The ??13C values are highly variable, but most are within the range -12??? to -91???. This variability may be diagnostic for identifying cold-seep-hydrate systems in the geologic record. Authigenic calcite is abundant in the cores down to ???1.5 m subbottom, the top of the methane hydrate. The calcite is depleted in 13C (??13C = -46??? to -58???), indicating that carbon produced by anaerobically oxidized methane is the main source of the calcite. Methane sources include a geologic hydrocarbon reservoir from Miocene source rocks, and biogenic and thermogenic degradation of organic matter in basin sediments. Oxygen isotopes indicate that most calcite formed out of isotopic equilibrium with ambient bottom water, under the influence of gas hydrate dissociation and strong methane flux. High metal content in the mud volcano sediment indicates leaching of basement rocks by fluid circulating along an underlying fault, which also allows for a high flux of fossil methane. ?? 2006 Geological Society of America.

  11. Effects of hydrated lime and quicklime on the decay of buried human remains using pig cadavers as human body analogues.

    PubMed

    Schotsmans, Eline M J; Denton, John; Dekeirsschieter, Jessica; Ivaneanu, Tatiana; Leentjes, Sarah; Janaway, Rob C; Wilson, Andrew S

    2012-04-10

    Recent casework in Belgium involving the search for human remains buried with lime, demonstrated the need for more detailed understanding of the effect of different types of lime on cadaver decomposition and its micro-environment. Six pigs (Sus scrofa) were used as body analogues in field experiments. They were buried without lime, with hydrated lime (Ca(OH)(2)) and with quicklime (CaO) in shallow graves in sandy loam soil in Belgium and recovered after 6 months of burial. Observations from these field recoveries informed additional laboratory experiments that were undertaken at the University of Bradford, UK. The combined results of these studies demonstrate that despite conflicting evidence in the literature, hydrated lime and quicklime both delay the decay of the carcass during the first 6 months. This study has implications for the investigation of clandestine burials and for a better understanding of archaeological plaster burials. Knowledge of the effects of lime on decomposition processes also has bearing on practices involving burial of animal carcasses and potentially the management of mass graves and mass disasters by humanitarian organisations and DVI teams.

  12. Simultaneous removal of colour, phosphorus and disinfection from treated wastewater using an agent synthesized from amorphous silica and hydrated lime.

    PubMed

    Yamashita, Takahiro; Aketo, Tsuyoshi; Minowa, Nobutaka; Sugimoto, Kiyomi; Yokoyama, Hiroshi; Ogino, Akifumi; Tanaka, Yasuo

    2013-01-01

    An agent synthesized from amorphous silica and hydrated lime (CSH-lime) was investigated for its ability to simultaneously remove the colour, phosphorus and disinfection from the effluents from wastewater treatment plants on swine farms. CSH-lime removed the colour and phosphate from the effluents, with the colour-removal effects especially high at pH 12, and phosphorous removal was more effective in strongly alkaline conditions (pH > 10). Colour decreased from 432 +/-111 (mean +/- SD) to 107 +/- 41 colour units and PO4(3-)P was reduced from 45 +/- 39 mg/L to undetectable levels at the CSH-lime dose of 2.0% w/v. Moreover, CSH-lime reduced the total organic carbon from 99.0 to 37.9 mg/L at the dose of 2.0% w/v and was effective at inactivating total heterotrophic and coliform bacteria. However, CSH-lime did not remove nitrogen compounds such as nitrite, nitrate and ammonium. Colour was also removed from dye solutions by CSH-lime, at the same dose.

  13. In-place stabilization of pond ash deposits by hydrated lime columns

    SciTech Connect

    Chand, S.K.; Subbarao, C.

    2007-12-15

    Abandoned coal ash ponds cover up vast stretches of precious land and cause environmental problems. Application of suitable in situ stabilization methods may bring about improvement in the geotechnical properties of the ash deposit as a whole, converting it to a usable site. In this study, a technique of in-place stabilization by hydrated lime columns was applied to large-scale laboratory models of ash ponds. Samples collected from different radial distances and different depths of the ash deposit were tested to study the improvements in the water content, dry density, particle size distribution, unconfined compressive strength, pH, hydraulic conductivity, and leachate characteristics over a period of one year. The in-place stabilization by lime column technique has been found effective in increasing the unconfined compressive strength and reducing hydraulic conductivity of pond ash deposits in addition to modifying other geotechnical parameters. The method has also proved to be useful in reducing the contamination potential of the ash leachates, thus mitigating the adverse environmental effects of ash deposits.

  14. Short-term effects of hydrated lime and quicklime on the decay of human remains using pig cadavers as human body analogues: Laboratory experiments.

    PubMed

    Schotsmans, Eline M J; Denton, John; Fletcher, Jonathan N; Janaway, Robert C; Wilson, Andrew S

    2014-05-01

    Contradictions and misconceptions regarding the effect of lime on the decay of human remains have demonstrated the need for more research into the effect of different types of lime on cadaver decomposition. This study follows previous research by the authors who have investigated the effect of lime on the decomposition of human remains in burial environments. A further three pig carcasses (Sus scrofa), used as human body analogues, were observed and monitored for 78 days without lime, with hydrated lime (Ca(OH)2) and with quicklime (CaO) in the taphonomy laboratory at the University of Bradford. The results showed that in the early stages of decay, the unlimed and hydrated lime cadavers follow a similar pattern of changes. In contrast, the application of quicklime instigated an initial acceleration of decay. Microbial investigation demonstrated that the presence of lime does not eliminate all aerobic bacteria. The experiment also suggested that lime functions as a sink, buffering the carbon dioxide evolution. This study complements the field observations. It has implications for the investigation of time since death of limed remains. Knowledge of the effects of lime on decomposition processes is of interest to forensic pathologists, archaeologists, humanitarian organisations and those concerned with disposal of animal carcasses or human remains in mass disasters.

  15. Long-term effects of hydrated lime and quicklime on the decay of human remains using pig cadavers as human body analogues: Field experiments.

    PubMed

    Schotsmans, Eline M J; Fletcher, Jonathan N; Denton, John; Janaway, Robert C; Wilson, Andrew S

    2014-05-01

    An increased number of police enquiries involving human remains buried with lime have demonstrated the need for more research into the effect of different types of lime on cadaver decomposition and its micro-environment. This study follows previous studies by the authors who have investigated the effects of lime on the decay of human remains in laboratory conditions and 6 months of field experiments. Six pig carcasses (Sus scrofa), used as human body analogues, were buried without lime with hydrated lime (Ca(OH)2) and quicklime (CaO) in shallow graves in sandy-loam soil in Belgium and recovered after 17 and 42 months of burial. Analysis of the soil, lime and carcasses included entomology, pH, moisture content, microbial activity, histology and lime carbonation. The results of this study demonstrate that despite conflicting evidence in the literature, the extent of decomposition is slowed down by burial with both hydrated lime and quicklime. The more advanced the decay process, the more similar the degree of liquefaction between the limed and unlimed remains. The end result for each mode of burial will ultimately result in skeletonisation. This study has implications for the investigation of clandestine burials, for a better understanding of archaeological plaster burials and potentially for the interpretation of mass graves and management of mass disasters by humanitarian organisation and DVI teams.

  16. Calcium sulfoaluminate (Ye'elimite) hydration in the presence of gypsum, calcite, and vaterite

    SciTech Connect

    Hargis, Craig W.; Telesca, Antonio; Monteiro, Paulo J.M.

    2014-11-15

    Six calcium sulfoaluminate-based cementitious systems composed of calcium sulfoaluminate, calcite, vaterite, and gypsum were cured as pastes and mortars for 1, 7, 28 and 84 days. Pastes were analyzed with X-ray diffraction, thermogravimetric and differential thermal analyses. Mortars were tested for compressive strength, dimensional stability and setting time. Furthermore, pastes with a water/cementitious material mass ratio of 0.80 were tested for heat evolution during the first 48 h by means of isothermal conduction calorimetry. It has been found that: (1) both calcite and vaterite reacted with monosulfoaluminate to give monocarboaluminate and ettringite, with vaterite being more reactive; (2) gypsum lowered the reactivity of both carbonates; (3) expansion was reduced by calcite and vaterite, irrespective of the presence of gypsum; and (4) both carbonates increased compressive strength in the absence of gypsum and decreased compressive strength less in the presence of gypsum, with vaterite's action more effective than that of calcite.

  17. Utilization of calcite and waste glass for preparing construction materials with a low environmental load.

    PubMed

    Maeda, Hirotaka; Imaizumi, Haruki; Ishida, Emile Hideki

    2011-11-01

    In this study, porous calcite materials are hydrothermally treated at 200 °C using powder compacts consisting of calcite and glasses composed of silica-rich soda-lime. After treatment, the glasses are converted into calcium aluminosilicate hydrates, such as zeolite phases, which increase their strength. The porosity and morphology of new deposits of hydrothermally solidified materials depend up on the chemical composition of glass. The use of calcite and glass in the hydrothermal treatment plays an important role in the solidification of calcite without thermal decomposition.

  18. Managing Salmonella Typhimurium and Escherichia coli O157:H7 in soil with hydrated lime - An outdoor study in lysimeters and field plots.

    PubMed

    Nyberg, Karin A; Vinnerås, Björn; Albihn, Ann

    2014-01-01

    An outbreak of Salmonella Typhimurium or E. coli O157:H7 among domestic animals can have great financial consequences for an animal enterprise but also be a threat for public health as there is a risk for transmission of the infection through the environment. In order to minimize disease transmission, it is important to treat not only the affected animals but also the areas on which they have been kept. In the present study, the effect of hydrated lime as a treatment for Salmonella Typhimurium or E. coli O157:H7 contaminated soil was investigated. The study was performed outdoors, in a lysimeter system and in field plots. The soils were spiked with Salmonella Typhimurium and/or E. coli O157:H7 and hydrated lime was added at three different concentrations (0.5, 1 and 2%). Sampling was performed over one month, and the levels of bacteria were analyzed by standard culture methods. In addition, the soil pH was monitored throughout the study. The results showed that application of 0.5-1 kg hydrated lime per m(2) reduced both Salmonella Typhimurium and E. coli O157:H7 numbers to below the detection limit (2 log10 CFU g-1 soil) in 3-7 days. Lower application rates of hydrated lime did not reduce pathogen numbers in the lysimeter study, but in the field plots no E. coli O157:H7 was detected at the end of the four-week study period regardless of hydrated lime application. A recommended strategy for treating a Salmonella Typhimurium or E. coli O157:H7 contaminated soil could therefore be to monitor the pH over the time of treatment and to repeat hydrated lime application if a decrease in pH is observed.

  19. Advanced treatment technique for swine wastewater using two agents: Thermally polymerized amorphous silica and hydrated lime for color and phosphorus removal and sulfur for nitrogen removal.

    PubMed

    Hasegawa, Teruaki; Kurose, Yohei; Tanaka, Yasuo

    2017-04-12

    The efficacy of advanced treatment of swine wastewater using thermally polymerized, modified amorphous silica and hydrated lime (M-CSH-lime) for color and phosphorus removal and sulfur for nitrogen removal was examined with a demonstration-scale treatment plant. The color removal rate was approximately 78% at M-CSH-lime addition rates of > 0.055 wt/v%. The PO43--P removal rate exceeded 99.9% with > 0.023 wt/v%. pH of the effluent from the M-CSH-lime reactor increased with the addition rate till a maximum value of 12.7, which was effective in disinfection. The recovered M-CSH-lime would be suitable as a phosphorus fertilizer because the total P2 O5 content was approximately 10%. The nitrogen oxide (NOx-N) removal rate by sulfur denitrification increased to approximately 80% when the NOx-N loading rate was around 0.1 kg-N/ton-S/day. It was suggested that the combination of the two processes would be effective in the advanced treatment of swine wastewater.

  20. Preparation of a new sorbent with hydrated lime and blast furnace slag for phosphorus removal from aqueous solution.

    PubMed

    Gong, Guozhuo; Ye, Shufeng; Tian, Yajun; Wang, Qi; Ni, Jiandi; Chen, Yunfa

    2009-07-30

    The removal of dissolvable inorganic phosphate (H(2)PO(4)(-)) by sorbents prepared from hydrated lime (HL) and blast furnace slag (BFS) was fundamentally studied by an orthogonal experiment design. Based on statistic analysis, it is revealed that the weight ratio of BFS/HL is the most significant variable, and an optimized preparation condition is figured out. With the increase of HL content, the adsorption capacity increases, suggesting that the HL plays the important role in the removal process in the gross. However, in the lower HL content, it is interesting that the adsorption capacity of as-prepared sorbents exceed the sum of the capacities of the same ratio of BFS and HL. The further analysis indicate the excess capacities linearly depend on the specific surface area of sorbents, suggesting that the removal of H(2)PO(4)(-) is closely related with the microstructure of sorbents in the lower HL content, according to the characterization with SEM, XRD and pore analysis. Additionally, an adsorption model and kinetic are discussed in this paper.

  1. Grenade Range Management Using Lime for Metals Immobilization and Explosives Transformation Treatability Study

    DTIC Science & Technology

    2007-06-01

    Calcitic hydrated lime K2CO3 Potassium carbonate KOH Potassium hydroxide NaOH Sodium hydroxide NH3-N Nitrogen-ammonia NO2/NO3 Nitrite/nitrate...munitions residues, metals are not degraded or easily detoxified. The most com- monly used treatment technologies for metals in soils on firing ranges...of an active firing range. Alkaline hydrolysis The use of the hydrolysis reaction as a means to degrade various environ- mental contaminants is

  2. Trichloroethylene decomposition and in-situ dry sorption of Cl-products by calcium oxides prepared from hydrated limes.

    PubMed

    Gotoh, Yoshimi; Iwata, Goichi; Choh, Kyaw; Kubota, Mitsuhiro; Matsuda, Hitoki

    2011-10-01

    A comparison of CaOs produced by calcining two types of hydrated lime and calcium carbonate was made for decomposition of trichloroethylene and in-situ dry sorption of the decomposed Cl-products using a lab-scale gas flow type tubular packed bed reactor. About 20 mg of CaO sample was mixed with about 2 g of Al2O3 particles and packed in the reactor and allowed to react with a flowing standard gas containing 500 ppm of C2HCl3 (N2 balance) at 673 and 873 K, under the condition that the reaction of CaO with C2HCl3 might be completed within a few hours. It was found that no thermal decomposition of C2HCl3 at or below 673 K was observed in a reactor packed only with Al2O3 particles. However, a considerable amount of decomposition of C2HCl3 was obtained in a reactor packed with CaO and Al2O3, even at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)2 at 673 K, decomposition of 0.42 mol of C2HCl3 and in-situ absorption product of 0.53 mol of CaCl2 were obtained. At 873 K, about 46% of C2HCl3 was thermally decomposed. The total amount of C2HCl3 decomposed in CaO-Al2O3 particle bed at 873 K became nearly twice larger than that at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)2 at 873 K, decomposition of 0.59 mol of C2HCl3 and in-situ absorption product of 0.67 mol of CaCl2 were obtained. Small amounts of C2Cl2, C2Cl4, CCl4, etc. were detected during decomposition of C2HCl3 at 673 and 873 K. It was recognized that the data on decomposition of C2HCl3 as well as in-situ dry sorption of Cl-products in CaO particle bed were correlated with specific surface area of the CaO employed.

  3. Mineral Resource of the Month: Lime

    USGS Publications Warehouse

    Corathers, Lisa

    2015-01-01

    Lime is the common term for several chemicals in three major categories: quicklime, hydrated lime and refractory dead-burned dolomite. Lime is almost never found naturally. It is primarily manufactured by burning limestone in kilns, followed by hydration when necessary. 

  4. Genesis and geometry of the Meiklejohn Peak lime mud-mound, Bare Mountain Quadrangle, Nevada, USA: Ordovician limestone with submarine frost heave structures—a possible response to gas clathrate hydrate evolution

    NASA Astrophysics Data System (ADS)

    Krause, Federico F.

    2001-12-01

    During the Early Middle Ordovician (Early Whiterockian) the Meiklejohn Peak lime mud-mound, a large whaleback or dolphin back dome, grew on a carbonate ramp tens to hundreds of kilometres offshore. This ramp extended from the northwest margin of Laurentia into the open waters of the ancestral Pacific Ocean to the north. The mound developed in an outer ramp environment, in relatively deep and cold water. A steep northern margin with a slope that exceeds 55° characterizes the mound. This margin is split by a 14-m long vertical fracture that separates a zone of slumped, drag-folded and brecciated rocks from the main mass of the mound. Failure along this fracture occurred subcutaneously, as highlighted by covering beds that are folded next to the mound. Brecciated blocks and clasts contain zebra and stromatactis structures indicating that these rocks and structures were lithified early in the history of the mound. The southern end of the mound is less steep and is characterized by large, echinodermal grainstone cross-beds. These deposits are part of a large, subaqueous dune that grew northwards and preceded the main development of the mound. Southward dipping and downlapping layers of mud-mound mudstone and wackestone overlie the dune. These muddy limestone layers are cut in several places by injection dykes and are pierced, near the contact with the underlying dune, by a 25-m long pipe filled with rotated nodular and brecciated mud-mound clasts. This long pipe extends to the edge of the mound and appears to have been a conduit where fluidized materials that came from the mound's interior were vented. The interior of the mound is typified by light grey limestone with zebra bands and stromatactis structures. Both structures represent former cavity systems that are filled with fibrous and bladed calcite and pelleted and laminated geopetal mudstone. Spar bands of zebra limestone often extend for several metres and appear to have been unsupported over these distances

  5. Evaluation of Ohio fly ash/hydrated lime slurries and Type 1 cement sorbent slurries in the U.C. Pilot spray dryer facility. Final report, September 1, 1993--August 31, 1994

    SciTech Connect

    Keener, T.C.; Khang, S.J.; Meyers, G.R.

    1995-02-01

    The objectives of this year`s work included an evaluation of the performance of fly ash/hydrated lime as well as hydrated cement sorbents for spray drying adsorption (SDA) of SO{sub 2} from a simulated high-sulfur flue gas. These sorbents were evaluated for several different hydration methods, and under different SDA operating conditions. In addition, the physical properties of surface area and porosity of the sorbents was determined. The most reactive fly ash/hydrated lime sorbent studied was prepared at room temperature with milled fly ash. Milling fly ash prior to hydration with lime did have a beneficial effect on calcium utilization. No benefit in utilization was experienced either by hydrating the slurries at a temperature of 90{degrees}C as compared to hydration at room temperature, or by increasing hydration time. While the surface areas varied greatly from sorbent to sorbent, the pore size distributions indicated ``ink bottle`` pores with surface porosity on the order of 0.5 microns. No correlation could be drawn between the surface area of the sorbents and calcium utilization. These results suggest that the composition of the resulting sorbent might be more important than its surface area. The most effective sorbent studied this year was produced by hydrating cement for 3 days at room temperature. This sorbent provided a removal efficiency and a calcium utilization over 25 percent higher than baseline results at an approach to saturation temperature of 30{degrees}F and a stoichiometric ratio of 0.9. A maximum SO{sub 2} removal efficiency of about 90 percent was experienced with this sorbent at an approach to saturation temperature of 20{degrees}F.

  6. [Study on Archaeological Lime Powders from Taosi and Yinxu Sites by FTIR].

    PubMed

    Wei, Guo-feng; Zhang, Chen; Chen, Guo-liang; He, Yu-ling; Gao, Jiang-tao; Zhang, Bing-jian

    2015-03-01

    Archaeological lime powders samples from Taosi and Yinxu sites, natural limestone and experimentally prepared lime mortar were investigated by means of Fourier transform infrared spectrometry (FTIR) to identify the raw material of lime powders from Taosi and Yinxu sites. Results show that ν2/ν4 ratio of calcite resulted from carbonation reaction of man-made lime is around 6.31, which is higher than that of calcite in natural limestone and reflects the difference in the disorder of calcite crystal structure among the natural limestone and prepared lime mortar. With additional grinding, the values of v2 and ν4 in natural limestone and prepared lime mortar decrease. Meanwhile, the trend lines of ν2 versus ν4 for calcite in experimentally prepared lime mortar have a steeper slope when compared to calcite in natural limestone. These imply that ν2/ν4 ratio and the slope of the trend lines of ν2 versus ν4 can be used to determine the archaeological man-made lime. Based on the experiment results, it is possible that the archaeological lime powder from Taosi and Yinxu sites was prepared using man-made lime and the ancient Chinese have mastered the calcining technology of man-made lime in the late Neolithic period about 4 300 years ago.

  7. Lime Pretreatment

    NASA Astrophysics Data System (ADS)

    Sierra, Rocio; Granda, Cesar Benigno; Holtzapple, Mark T.

    Lime pretreatment has proven to be a useful method for selectively reducing the lignin content of lignocellulosic biomass without significant loss in carbohydrates, thus realizing an important increase in biodigestibility. In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be accomplished in one of three fashions: (1) short-term pretreatment that lasts up to 6 h, requires temperatures of 100-160°C, and can be applied with or without oxygen (pressure ~200 psig); (2) long-term pretreatment taking up to 8 weeks, requiring only 55-65°C, and capable of running with or without air (atmospheric pressure); and (3) simple pretreatment requiring 1 h in boiling water, without air or oxygen. Nonoxidative conditions are effective at low lignin contents (below ~18% lignin), whereas oxidative conditions are required for high lignin contents (above ~18% lignin).

  8. Lime pretreatment.

    PubMed

    Sierra, Rocio; Granda, Cesar Benigno; Holtzapple, Mark T

    2009-01-01

    Lime pretreatment has proven to be a useful method for selectively reducing the lignin content of lignocellulosic biomass without significant loss in carbohydrates, thus realizing an important increase in biodigestibility. In lime pretreatment, the biomass is pretreated with calcium hydroxide and water under different conditions of temperature and pressure. It can be accomplished in one of three fashions: (1) short-term pretreatment that lasts up to 6 h, requires temperatures of 100-160 degrees C, and can be applied with or without oxygen (pressure approximately 200 psig); (2) long-term pretreatment taking up to 8 weeks, requiring only 55-65 degrees C, and capable of running with or without air (atmospheric pressure); and (3) simple pretreatment requiring 1 h in boiling water, without air or oxygen. Nonoxidative conditions are effective at low lignin contents (below approximately 18% lignin), whereas oxidative conditions are required for high lignin contents (above approximately 18% lignin).

  9. An integrated study of limestone behavior during calcination and hydration processes

    NASA Astrophysics Data System (ADS)

    Leontakianakos, George; Baziotis, Ioannis; Kiousis, George; Giavis, Dimitrios; Tsimas, Stamatios

    2010-05-01

    One of the most important processes in industrial scale, represents the dissociation of carbonates to lime and CO2. This process, called calcination, occur at relative high temperatures (>9000C). Lime rapidly reacts with the water, liberating high amounts of heat producing Ca(OH)2. For the purpose of the present study five samples of different limestones from different quarries from Greece were collected. The aim of the study was to analyze the behavior of the limestones during calcination and test the hydraulic properties of the quick lime. Limestone particles (1.6-2 cm) were reacted in a pre-heated oven at three different temperatures (900, 1050 and 1200oC) for 30 min in order to produce quick lime. Petrographic features of studied limestones were done using secondary electron microscopy (SEM). X-ray diffractometry and Raman micro-spectroscopy were applied in order to identify the carbonate phases (calcite and dolomite) in the studied limestones. Chemical composition of limestones and limes were determined by Atomic absorption spectroscopy (AAS) method. 25 gr of the produced lime were hydrated by adding 100 ml distilled water having a room temperature (~250C) to produce Ca(OH)2 through the exothermic reaction CaO(s) + H2O(l)-Ca(OH)2(aq). We measured the temperature difference in the water until a maximum value is reached; this value represents the reactivity of the produced slaked lime. Chemical composition and reactivity estimation were done following European Standards EN-459-2. The reactivity of quick lime depends on various factors with the most important being the internal structure of the limestone, calcination temperature/duration applied to the limestone, the admixtures such as the MgO content, hard-burned phenomena etc. The treatment of the experimental results suggests the following: i) The (CaO+MgO)Lime value have similar variation for both samples calcined at temperatures of 1050oC (58-90 wt%) and 1200oC (57-94 wt%); whereas the samples calcined at

  10. Kinetics of the reaction of iron blast furnace slag/hydrated lime sorbents with SO{sub 2} at low temperatures: effects of the presence of CO{sub 2}, O{sub 2}, and NOx

    SciTech Connect

    Liu, C.F.; Shih, S.M.

    2009-09-15

    The effects of the presence of CO{sub 2}, O{sub 2}, and NOx in the flue gas on the kinetics of the sulfation of blast furnace slag/hydrated lime sorbents at low temperatures were studied using a differential fixed-bed reactor. When O{sub 2} and NOx were not present simultaneously, the reaction kinetics was about the same as that under the gas mixtures containing SO{sub 2}, H{sub 2}O, and N{sub 2} only, being affected mainly by the relative humidity. The sulfation of sorbents can be described by the surface coverage model and the model equations derived for the latter case. When both O{sub 2} and NOx, were present, the sulfation of sorbents was greatly enhanced, forming a great amount of sulfate in addition to sulfite. The surface coverage model is still valid in this case, but the model equations obtained show a more marked effect of relative humidity and negligible effects of SO{sub 2} concentration and temperature on the reaction. The effect of sorbent composition on the reaction kinetics was entirely represented by the effects of the initial specific surface area (S{sub g0}) and the Ca molar content (M{sup -1}) of sorbent. The initial conversion rate of sorbent increased linearly with increasing S{sub g0}, and the ultimate conversion increased linearly with increasing S{sub g0}M{sup -1}. The model equations obtained in this work are applicable to describe the kinetics of the sulfation of the sorbents in the low-temperature dry and semidry fine gas desulfurization processes either with an upstream NOx, removal unit or without.111

  11. High surface area calcite

    NASA Astrophysics Data System (ADS)

    Schultz, L. N.; Andersson, M. P.; Dalby, K. N.; Müter, D.; Okhrimenko, D. V.; Fordsmand, H.; Stipp, S. L. S.

    2013-05-01

    Calcite (CaCO3) is important in many fields—in nature, because it is a component of aquifers, oil reservoirs and prospective CO2 storage sites, and in industry, where it is used in products as diverse as paper, toothpaste, paint, plastic and aspirin. It is difficult to obtain high purity calcite with a high surface area but such material is necessary for industrial applications and for fundamental calcite research. Commercial powder is nearly always contaminated with growth inhibitors such as sugars, citrate or pectin and most laboratory synthesis methods deliver large precipitates, often containing vaterite or aragonite. To address this problem, we (i) adapted the method of carbonating a Ca(OH)2 slurry with CO2 gas to develop the first simple, cheap, safe and reproducible procedure using common laboratory equipment, to obtain calcite that reproducibly had a surface area of 14-17 m2/g and (ii) conducted a thorough characterization of the product. Scanning electron microscopy (SEM) revealed nanometer scale, rhombohedral crystals. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (IR) confirmed highly crystalline, pure calcite that more closely resembles the dimensions of the biogenic calcite produced by algae in coccoliths than other methods for synthesizing calcite. We suggest that this calcite is useful when purity and high surface area are important.

  12. Agricultural Liming, Irrigation, and Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    McGill, B. M.; Hamilton, S. K.

    2015-12-01

    Row crop farmers routinely add inorganic carbon to soils in the form of crushed lime (e.g., calcite or dolomite minerals) and/or inadvertently as bicarbonate alkalinity naturally dissolved in groundwater used for irrigation. In the soil these carbonates can act as either a source or sink of carbon dioxide, depending in large part on nitrogen fertilization and nitrification. The potentially variable fate of lime carbon is not accounted for in the IPCC greenhouse gas inventory model for lime emissions, which assumes that all lime carbon becomes carbon dioxide (irrigation additions are not accounted for). In a corn-soybean-wheat crop rotation at the Kellogg Biological Station Long Term Ecological Research site in southwest Michigan, we are collecting soil porewater from several depths in the vadose zone across a nitrogen fertilizer gradient with and without groundwater irrigation. The soil profile in this region is dominated by carbonate rich glacial outwash that lies 1.5 m below a carbonate-leached zone. We analyze the porewater stoichiometry of calcium, magnesium, and carbonate alkalinity in a conceptual model to reveal the source/sink fate of inorganic carbon. High nitrate porewater concentrations are associated with net carbon dioxide production in the carbonate-leached zone, according to our model. This suggests that the acidity associated with nitrification of the nitrogen fertilizer, which is evident from soil pH measurements, is driving the ultimate fate of lime carbon in the vadose zone. Irrigation is a significant source of both alkalinity and nitrate in drier years, compared to normal rates of liming and fertilization. We will also explore the observed dramatic changes in porewater chemistry and the relationship between irrigation and inorganic carbon fate above and within the native carbonate layer.

  13. Defects in Calcite.

    DTIC Science & Technology

    1991-05-13

    AD-A245 645 A TRIDENT SCHOLAR PROJECT REPORT NO. 181 "DEFECTS IN CALCITE " DTTC %N FEB 5-1912 UNITED STATES NAVAL ACADEMY ANNAPOLIS, MARYLAND 92-02841...report; no. 181 (1991) "DEFECTS IN CALCITE " A Trident Scholar Project Report by Midshipman Anthony J. Kotarski, Class of 1991 U. S. Naval Academy Annapolis...REPORT TYPE AND DATES COVERED 13 May 1991 Final 1990/91 . TITLE AND SUBTITLE s. FUNDING NUMBERS DEFECTS IN CALCITE 6. AUTHOR(S) Anthony J. Kotarski 7

  14. Sewage sludge treatment with lime.

    PubMed

    Herbst, B

    2000-01-01

    The article describes the application of lime as a method for treatment and hygienisation of sewage sludges with lime products such as quicklime, slake lime and dolomitic lime. As a result of the increase in temperature and pH-value during sludge and lime mixing most pathogenic vectors of disease (i.e. bacteria, worms, viruses and parasites) are reduced in concentration and viability to manufacture a safe product for further application on agricultural land.

  15. Marine diagenesis of Lower Ordovician carbonate sediments (Dumugol Formation), Korea: cementation in a calcite sea

    NASA Astrophysics Data System (ADS)

    Kim, Jeong Chan; Lee, Yong Il

    1996-09-01

    The Lower Ordovician Dumugol Formation exhibits many features that indicate early lithification, such as calcite nodules, hardgrounds, mud-mounds and intraclasts. Detailed observations of these early-lithified features reveal that rapid marine cementation was instrumental in their formation. Marine lithification took place in a low-energy subtidal environmental that was influenced by intermittent storms. Marine cements include syntaxial overgrowth, bladed calcite, fibrous calcite and fine-crystalline equant calcite cements. Syntaxial overgrowths precipitated on echinoderm grains and contributed to rapid marine lithification of echinoderm-bearing sediments. Bladed, fibrous, and fine-crystalline equant calcite cements precipitated in locally suitable sites but their occurrence is limited, and thus played a minor role in marine lithification. Microcrystalline calcites also precipitated in lime mud-rich, fine-grained sediments and participated in rapid marine lithification of the Dumugol sediments. The absence of aragonite allochems and cement, and the predominance of calcite cement, suggest that the Dumugol sea was undersaturated with respect to aragonite, but supersaturated with respect to calcite, which is indicative of a 'calcite sea'.

  16. Elastic constants of calcite

    USGS Publications Warehouse

    Peselnick, L.; Robie, R.A.

    1962-01-01

    The recent measurements of the elastic constants of calcite by Reddy and Subrahmanyam (1960) disagree with the values obtained independently by Voigt (1910) and Bhimasenachar (1945). The present authors, using an ultrasonic pulse technique at 3 Mc and 25??C, determined the elastic constants of calcite using the exact equations governing the wave velocities in the single crystal. The results are C11=13.7, C33=8.11, C44=3.50, C12=4.82, C13=5.68, and C14=-2.00, in units of 1011 dyncm2. Independent checks of several of the elastic constants were made employing other directions and polarizations of the wave velocities. With the exception of C13, these values substantially agree with the data of Voigt and Bhimasenachar. ?? 1962 The American Institute of Physics.

  17. Hydrate detection

    SciTech Connect

    Dillon, W.P.; Ahlbrandt, T.S.

    1992-06-01

    Project objectives were: (1) to create methods of analyzing gas hydrates in natural sea-floor sediments, using available data, (2) to make estimates of the amount of gas hydrates in marine sediments, (3) to map the distribution of hydrates, (4) to relate concentrations of gas hydrates to natural processes and infer the factors that control hydrate concentration or that result in loss of hydrate from the sea floor. (VC)

  18. Hydrate detection

    SciTech Connect

    Dillon, W.P.; Ahlbrandt, T.S.

    1992-01-01

    Project objectives were: (1) to create methods of analyzing gas hydrates in natural sea-floor sediments, using available data, (2) to make estimates of the amount of gas hydrates in marine sediments, (3) to map the distribution of hydrates, (4) to relate concentrations of gas hydrates to natural processes and infer the factors that control hydrate concentration or that result in loss of hydrate from the sea floor. (VC)

  19. Reaction-induced fracturing in a hot pressed calcite-periclase aggregate

    NASA Astrophysics Data System (ADS)

    Kuleci, H.; Ulven, O. I.; Rybacki, E.; Wunder, B.; Abart, R.

    2017-01-01

    The chemo-mechanical feedbacks associated with hydration of periclase immersed in a calcite matrix were investigated experimentally. Dense calcite-periclase aggregates with <5% porosity and with a calcite to periclase ratio of 90/10 and 95/5 by volume were prepared by hot isostatic pressing. Subsequent hydration experiments were performed in a hydrothermal apparatus at temperatures of 580-610 °C and a pressure of 200 MPa for run durations of 5-60 min. The rate of the periclase to brucite transformation was primarily controlled by the access of fluid. Where fluid was present, the reaction was too fast for the associated positive volume increase of the solids of about 100% to be accommodated by creep of the calcite matrix, and fracturing was induced. The newly formed cracks greatly enhanced the access of fluid leading to a positive feedback between hydration and fracturing. Mostly the newly formed cracks follow pre-existing grain boundaries in the calcite matrix. Comparison of experimental results with numerical 2D discrete element modelling (DEM) of crack formation revealed that the geometry of the crack pattern around a reacting particle depends on the shape of the original periclase particle, on the mechanical strength of the particle-matrix interface and on the mechanical strength and arrangement of grain boundaries in the calcite matrix in the immediate vicinity of the swelling particle.

  20. Morphology Controls on Calcite Recrystallization.

    PubMed

    Heberling, Frank; Paulig, Leonie; Nie, Zhe; Schild, Dieter; Finck, Nicolas

    2016-11-01

    Environmental scientists and geoscientists working in different fields regard the reactivity of calcite and corresponding changes in its trace elemental- or isotopic composition from diametrically opposed points of view. As one extreme, calcite based environmental remediation strategies rely on the fast recrystallization of calcite and the concurrent uptake and immobilization of pollutants. Paleo-ecological investigations denote the other extreme, and rely on the invariability of calcite composition over geological periods of time. We use long-term radiotracer experiments to quantify recrystallization rates of seven types of calcite powder with diverse morphology and particle size distribution. On the one hand our results demonstrate the long-term metastability of calcite with equilibrated crystal surfaces even at isotopic dis-equilibrium. On the other hand, we document the extremely high reactivity and interfacial free energy of freshly ground, rough calcite. Our results indicate that bulk calcite recrystallization is an interfacial free energy driven Ostwald-ripening process, in which particle roughness effects dominate over the effect of crystal habitus and particle size. We confirm that the dynamic equilibrium exchange of crystal constituents between kink sites involves an activation barrier of about 25 kJ/mol. At room temperature the equilibrium exchange is limited to a near surface region and proceeds at a rate of (3.6 ± 1.4)·10(-13) mol/(m(2)·s).

  1. Water transfer properties and shrinkage in lime-based rendering mortars

    NASA Astrophysics Data System (ADS)

    Arizzi, A.; Cultrone, G.

    2012-04-01

    Rendering is the practice of covering a wall or a building façade with one or more layers of mortar, with the main aim to protect the masonry structure against weathering. The render applied must show high flexibility, good adhesion and compatibility with the support (i.e. stone, brick) and, overall, it should be characterised by low water absorption and high water vapour permeability. Water (in the solid, liquid and vapour state) is one of the main factors that drive construction materials to deterioration. Therefore, to evaluate the quality and durability of a rendering mortar, thus ensuring its protective function in the masonry structure, it is fundamental to assess the behaviour of this mortar towards water. Mortars were elaborated with a calcitic dry hydrated lime, a calcareous aggregate, a pozzolan, a lightweight aggregate, a water-retaining agent and a plasticiser. Four types of lime mortars were prepared, in which the binder-to-aggregate ratios were 1:3, 1:4, 1:6 and 1:9 by weight, whilst the pozzolan was kept at 10% of the lime (by mass) and the total admixtures proportion was less than 2% of the total mass. The influence of the characteristics of mortars pore system on the amount of water absorbed and the kinetics of absorption was investigated by means of: free water absorption and drying; capillary uptake; water permeability; water vapour permeability. Interesting deductions can be made from the values of water and water vapour permeability found for mortars: the former increases exponentially with the sand volume of the mortar, whilst the latter increases almost exponentially with the initial water content added to the mortar mixes during their elaboration. However, the relationship obtained between porosity of mortars and permeability values is not really clear. This finding suggests that the permeability of a material cannot be estimated on the basis of its porosity as it can be made for the capillary uptake and free water absorption. Another

  2. Tracing formation and durability of calcite in a Punic-Roman cistern mortar (Pantelleria Island, Italy).

    PubMed

    Dietzel, Martin; Schön, Frerich; Heinrichs, Jens; Deditius, Artur P; Leis, Albrecht

    2016-01-01

    Ancient hydraulic lime mortar preserves chemical and isotopic signatures that provide important information about historical processing and its durability. The distribution and isotopic composition of calcite in a mortar of a well-preserved Punic-Roman cistern at Pantelleria Island (Italy) was used to trace the formation conditions, durability, and individual processing periods of the cistern mortar. The analyses of stable carbon and oxygen isotopes of calcite revealed four individual horizons, D, E, B-1 and B-2, of mortar from the top to the bottom of the cistern floor. Volcanic and ceramic aggregates were used for the production of the mortar of horizons E/D and B-1/B-2, respectively. All horizons comprise hydraulic lime mortar characterized by a mean cementation index of 1.5 ± 1, and a constant binder to aggregate ratio of 0.31 ± 0.01. This suggests standardized and highly effective processing of the cistern. The high durability of calcite formed during carbonation of slaked lime within the matrix of the ancient mortar, and thus the excellent resistance of the hydraulic lime mortar against water, was documented by (i) a distinct positive correlation of δ(18)Ocalcite and δ(13)Ccalcite; typical for carbonation through a mortar horizon, (ii) a characteristic evolution of δ(18)Ocalcite and δ(13)Ccalcite through each of the four mortar horizons; lighter follow heavier isotopic values from upper to lower part of the cistern floor, and (iii) δ(18)Ocalcite varying from -10 to -5 ‰ Vienna Pee Dee belemnite (VPDB). The range of δ(18)Ocalcite values rule out recrystallization and/or neoformation of calcite through chemical attack of water stored in cistern. The combined studies of the chemical composition of the binder and the isotopic composition of the calcite in an ancient mortar provide powerful tools for elucidating the ancient techniques and processing periods. This approach helps to evaluate the durability of primary calcite and demonstrates the

  3. Incorporation of Eu(III) into Calcite under Recrystallization conditions.

    PubMed

    Hellebrandt, S E; Hofmann, S; Jordan, N; Barkleit, A; Schmidt, M

    2016-09-13

    The interaction of calcite with trivalent europium under recrystallization conditions was studied on the molecular level using site-selective time-resolved laser fluorescence spectroscopy (TRLFS). We conducted batch studies with a reaction time from seven days up to three years with three calcite powders, which differed in their specific surface area, recrystallization rates and impurities content. With increase of the recrystallization rate incorporation of Eu(3+) occurs faster and its speciation comes to be dominated by one species with its excitation maximum at 578.8 nm, so far not identified during previous investigations of this process under growth and phase transformation conditions. A long lifetime of 3750 μs demonstrates complete loss of hydration, consequently Eu must have been incorporated into the bulk crystal. The results show a strong dependence of the incorporation kinetics on the recrystallization rate of the different calcites. Furthermore the investigation of the effect of different background electrolytes (NaCl and KCl) demonstrate that the incorporation process under recrystallization conditions strongly depends on the availability of Na(+). These findings emphasize the different retention potential of calcite as a primary and secondary mineral e.g. in a nuclear waste disposal site.

  4. Incorporation of Eu(III) into Calcite under Recrystallization conditions

    PubMed Central

    Hellebrandt, S. E.; Hofmann, S.; Jordan, N.; Barkleit, A.; Schmidt, M.

    2016-01-01

    The interaction of calcite with trivalent europium under recrystallization conditions was studied on the molecular level using site-selective time-resolved laser fluorescence spectroscopy (TRLFS). We conducted batch studies with a reaction time from seven days up to three years with three calcite powders, which differed in their specific surface area, recrystallization rates and impurities content. With increase of the recrystallization rate incorporation of Eu3+ occurs faster and its speciation comes to be dominated by one species with its excitation maximum at 578.8 nm, so far not identified during previous investigations of this process under growth and phase transformation conditions. A long lifetime of 3750 μs demonstrates complete loss of hydration, consequently Eu must have been incorporated into the bulk crystal. The results show a strong dependence of the incorporation kinetics on the recrystallization rate of the different calcites. Furthermore the investigation of the effect of different background electrolytes (NaCl and KCl) demonstrate that the incorporation process under recrystallization conditions strongly depends on the availability of Na+. These findings emphasize the different retention potential of calcite as a primary and secondary mineral e.g. in a nuclear waste disposal site. PMID:27618958

  5. Incorporation of Eu(III) into Calcite under Recrystallization conditions

    NASA Astrophysics Data System (ADS)

    Hellebrandt, S. E.; Hofmann, S.; Jordan, N.; Barkleit, A.; Schmidt, M.

    2016-09-01

    The interaction of calcite with trivalent europium under recrystallization conditions was studied on the molecular level using site-selective time-resolved laser fluorescence spectroscopy (TRLFS). We conducted batch studies with a reaction time from seven days up to three years with three calcite powders, which differed in their specific surface area, recrystallization rates and impurities content. With increase of the recrystallization rate incorporation of Eu3+ occurs faster and its speciation comes to be dominated by one species with its excitation maximum at 578.8 nm, so far not identified during previous investigations of this process under growth and phase transformation conditions. A long lifetime of 3750 μs demonstrates complete loss of hydration, consequently Eu must have been incorporated into the bulk crystal. The results show a strong dependence of the incorporation kinetics on the recrystallization rate of the different calcites. Furthermore the investigation of the effect of different background electrolytes (NaCl and KCl) demonstrate that the incorporation process under recrystallization conditions strongly depends on the availability of Na+. These findings emphasize the different retention potential of calcite as a primary and secondary mineral e.g. in a nuclear waste disposal site.

  6. Mineral phases of green liquor dregs, slaker grits, lime mud and wood ash of a Kraft pulp and paper mill.

    PubMed

    Martins, Fernanda Machado; Martins, Joaniel Munhoz; Ferracin, Luiz Carlos; da Cunha, Carlos Jorge

    2007-08-17

    Four residues generated in a Kraft, pulp and paper plant, were characterized by X-ray fluorescence spectroscopy (XFA), powder X-ray diffraction (XRD), thermogravimmetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). A quantitative phase composition model, that accounts for the observed data and for the physico-chemical conditions of formation, was postulated for each material. Emphasis was given on the identification of the mineral components of each material. The green liquor dregs and the lime mud contain Calcite and Gipsite. The slaker grits contains Calcite, Portlandite, Pirssonite, Larnite and Brucite. The Calcite phase, present in the dregs and in the lime mud, has small amounts of magnesium replacing calcium. The wood ash contains Quartz as the major crystalline mineral phase.

  7. Experimental study of the replacement of calcite by calcium sulphates

    NASA Astrophysics Data System (ADS)

    Ruiz-Agudo, E.; Putnis, C. V.; Hövelmann, J.; Álvarez-Lloret, P.; Ibáñez-Velasco, A.; Putnis, A.

    2015-05-01

    Among the most relevant mineral replacement reactions are those involving sulphates and carbonates, which have important geological and technological implications. Here it is shown experimentally that during the interaction of calcite (CaCO3) cleavage surfaces with sulphate-bearing acidic solutions, calcite is ultimately replaced by gypsum (CaSO4 2H2O) and anhydrite (CaSO4), depending on the reaction temperature. Observations suggest that this occurs most likely via an interface-coupled dissolution-precipitation reaction, in which the substrate is replaced pseudomorphically by the product. At 120 and 200 °C gypsum and/or bassanite (CaSO4·0.5H2O) form as precursor phases for the thermodynamically stable anhydrite. Salinity promotes the formation of less hydrated precursor phases during the replacement of calcite by anhydrite. The reaction stops before equilibrium with respect to calcite is reached and during the course of the reaction most of the bulk solutions are undersaturated with respect to the precipitating phase(s). A mechanism consisting of the dissolution of small amounts of solid in a thin layer of fluid at the mineral-fluid interface and the subsequent precipitation of the product phase from this layer is in agreement with these observations. PHREEQC simulations performed in the framework of this mechanism highlight the relevance of transport and surface reaction kinetics on the volume change associated with the CaCO3-CaSO4 replacement. Under our experimental conditions, this reaction occurs with a positive volume change, which ultimately results in passivation of the unreacted substrate before calcite attains equilibrium with respect to the bulk solution.

  8. A study on engineering characteristics of asphalt concrete using filler with recycled waste lime.

    PubMed

    Sung Do, Hwang; Hee Mun, Park; Suk keun, Rhee

    2008-01-01

    This study focuses on determining the engineering characteristics of asphalt concrete using mineral fillers with recycled waste lime, which is a by-product of the production of soda ash (Na(2)CO(3)). The materials tested in this study were made using a 25%, 50%, 75%, and 100% mixing ratio based on the conventional mineral filler ratio to analyze the possibility of using recycled waste lime. The asphalt concretes, made of recycled waste lime, hydrated lime, and conventional asphalt concrete, were evaluated through their fundamental engineering properties such as Marshall stability, indirect tensile strength, resilient modulus, permanent deformation characteristics, moisture susceptibility, and fatigue resistance. The results indicate that the application of recycled waste lime as mineral filler improves the permanent deformation characteristics, stiffness and fatigue endurance of asphalt concrete at the wide range of temperatures. It was also determined that the mixtures with recycled waste lime showed higher resistance against stripping than conventional asphalt concrete. It was concluded from various test results that a waste lime can be used as mineral filler and, especially, can greatly improve the resistance of asphalt concrete to permanent deformation at high temperatures.

  9. Kinetics of Mg partition and Mg stable isotope fractionation during its incorporation in calcite

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; Gautier, Quentin; Bosc, Olivier; Schott, Jacques

    2013-08-01

    precipitation rate. This behavior likely stems from the strong free energy of hydration of the Mg2+ ion compared to Ca2+, Ba2+ and Sr2+ which leads, during fast calcite growth, to the entrapment in calcite overgrowths of hydrated Mg ions whose isotopic composition is close to that of aqueous Mg2+. The strong dependence of Mg isotope fractionation on calcite growth rate suggests that, using the three isotopes method, Mg isotopic signatures of calcite in association with those of other divalent metals (Zn2+, Cu2+) have the potential to reveal mineral precipitation rates and thus environmental conditions of the oceans over geological time.

  10. Adhesion force between cyclopentane hydrate and mineral surfaces.

    PubMed

    Aman, Zachary M; Leith, William J; Grasso, Giovanny A; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

    2013-12-17

    Clathrate hydrate adhesion forces play a critical role in describing aggregation and deposition behavior in conventional energy production and transportation. This manuscript uses a unique micromechanical force apparatus to measure the adhesion force between cyclopentane hydrate and heterogeneous quartz and calcite substrates. The latter substrates represent models for coproduced sand and scale often present during conventional energy production and transportation. Micromechanical adhesion force data indicate that clathrate hydrate adhesive forces are 5-10× larger for calcite and quartz minerals than stainless steel. Adhesive forces further increased by 3-15× when increasing surface contact time from 10 to 30 s. In some cases, liquid water from within the hydrate shell contacted the mineral surface and rapidly converted to clathrate hydrate. Further measurements on mineral surfaces with physical control of surface roughness showed a nonlinear dependence of water wetting angle on surface roughness. Existing adhesive force theory correctly predicted the dependence of clathrate hydrate adhesive force on calcite wettability, but did not accurately capture the dependence on quartz wettability. This comparison suggests that the substrate surface may not be inert, and may contribute positively to the strength of the capillary bridge formed between hydrate particles and solid surfaces.

  11. Corrosion Protection by Calcite-Type Coatings

    DTIC Science & Technology

    1989-10-01

    CORROSION PROTECTION BY CALCITE -TYPE COATINGS OCTOBER, 1989 Prepared by: OCEAN CITY RESEARCH CORPORATION Tennessee Avenue & Beach Thorofare Ocean...REPORT DATE OCT 1989 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Corrosion Protection by Calcite -Type Coatings 5a. CONTRACT... calcite -type coatings to segregated seawater ballast tanks. If perfected, a calcite coating approach could substantially reduce the cost of corrosion

  12. Hydrothermal preparation of diatomaceous earth combined with calcium silicate hydrate gels.

    PubMed

    Maeda, Hirotaka; Ishida, Emile Hideki

    2011-01-30

    A novel composite for the removal of color in waste water was prepared by subjecting slurries consisting diatomaceous earth and slaked lime to a hydrothermal reaction at 180 °C. Subsequently, calcium silicate hydrate gels covered the surface of diatomaceous earth due to the reaction between the amorphous silica of diatomaceous earth and slaked lime. The formation of calcium silicate hydrate gels led to an increase in the specific surface area. The composites showed higher methylene blue adsorption capacity compared with diatomaceous earth. The improved adsorption capacity of the composites depended on the amount of the calcium silicate hydrate gels and their silicate anion chain-lengths.

  13. Lime pretreatment of lignocellulosic biomass

    NASA Astrophysics Data System (ADS)

    Chang, Shushien

    Lignocellulose is a valuable alternative energy source. The susceptibility of lignocellulosic biomass to enzymatic hydrolysis is constrained due to its structural features, so pretreatment is essential to enhance enzymatic digestibility. Of the chemicals used as pretreatment agents, it has been reported that alkalis improve biomass digestibility significantly. In comparison with other alkalis such as NaOH and ammonia, lime (calcium hydroxide) has many advantages; it is very inexpensive, is safe, and can be recovered by carbonating wash water. The effects of lime pretreatment were explored on switchgrass and poplar wood, representing herbaceous and woody biomass, respectively. The effects of pretreatment conditions (time, temperature, lime loading, water loading, particle size, and oxygen pressure) have been systematically studies. Lime alone enhances the digestibility of switchgrass significantly; under the recommended conditions, the 3-d total sugar (glucose + xylose) yields of lime-treated switchgrass were 7 times that of untreated sample. When treating poplar wood, lime must be combined with oxygen to achieve high digestibility; oxidative lime pretreatment increased the 3-d total sugar yield of poplar wood to 12 times that of untreated sample. In a fundamental study, to determine why lime pretreatment is effective, the effects of three structural features on enzymatic digestibility were studied: lignin content, acetyl content, and crystallinity index (CrI). Poplar wood was treated with peracetic acid, potassium hydroxide, and ball milling to produce model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and CrI, respectively. Enzymatic hydrolysis was performed on the model lignocelluloses to determine the digestibility. Correlations between lignin/carbohydrate ratio, acetyl/carbohydrate ratio, CrI and digestibility were developed. The 95% prediction intervals show that the correlations predict the 1-h and 3-d total sugar conversions of

  14. Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials.

    PubMed

    Kaszowska, Zofia; Malek, Kamilla; Staniszewska-Slezak, Emilia; Niedzielska, Karina

    2016-12-05

    This work presents an in-depth study on Raman spectra excited with 1064 and 532nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064nm, but absent in the corresponding spectra acquired with laser excitation at 532nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064nm excitation.

  15. Raman scattering or fluorescence emission? Raman spectroscopy study on lime-based building and conservation materials

    NASA Astrophysics Data System (ADS)

    Kaszowska, Zofia; Malek, Kamilla; Staniszewska-Slezak, Emilia; Niedzielska, Karina

    2016-12-01

    This work presents an in-depth study on Raman spectra excited with 1064 and 532 nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064 nm, but absent in the corresponding spectra acquired with laser excitation at 532 nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064 nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064 nm excitation.

  16. Mineral resource of the month: lime

    USGS Publications Warehouse

    ,

    2009-01-01

    The article presents facts about lime, which is said to be a caustic chemical manufactured from limestone or other calcium carbonates in a kiln at temperatures ranging from 935 to 1,350 degrees Celsius. It states that lime is widely used in industries such as steelmaking, paper production and chemical manufacturing. It also mentions that global lime production amounts up to 280 million metric tons annually. However, it notes that international trade in lime is limited.

  17. Structure of the (1014) Surfaces of Calcite, Dolomite, and Magnesite under Wet and Dry Conditions

    SciTech Connect

    WRIGHT,KATE; CYGAN,RANDALL T.; SLATER,BEN

    2000-06-12

    Atomistic computer simulation methods have been employed to model the structure of the (10{bar 1}4) surfaces of calcite, dolomite and magnesite. The authors calculations show that under vacuum conditions, calcite undergoes the greatest degree of surface relaxation with rotation and distortion of the carbonate group accompanied by movement of the calcium ion. The magnesite surface is the least distorted of the three carbonates, with dolomite being intermediate to the two end members. When water molecules are placed on the surface to produce complete monolayer coverage, the calcite surface is stabilized and the amount of relaxation is substantially reduced. In contrast, the dolomite and magnesite surfaces are destabilized by hydration as indicated by a significant increase in the surface energies relative to the dry surface.

  18. Shock-induced devolatilization of calcite

    NASA Technical Reports Server (NTRS)

    Boslough, M. B.; Ahrens, T. J.; Vizgirda, J.; Becker, R. H.; Epstein, S.

    1982-01-01

    Experimental measurements of the release adiabats by Vizgirda (1981) indicate that substantial vaporization takes place upon release from shock pressures of 37 GPa for calcite and 14 GPa for aragonite. The present investigation includes the first controlled partial vaporization experiments on calcite. The experiments were conducted to test the predictions of the release adiabat experiments. The quantities of the gaseous species produced from shocked calcite and their carbon and oxygen isotopic compositions were determined, and the shock-induced effect on the Mn(2+) electron spin resonance spectrum in the shock-recovered calcite was observed. On the basis of the obtained results, it is concluded that shock stresses at the 17-18 GPa level give rise to volatilization of 0.03-0.3 (mole) percent of calcite to CO2 and CO. The devolatilization of calcite occurs at low pressure at significantly lower entropy densities than predicted on the basis of thermodynamic continuum models.

  19. A model for trace metal sorption processes at the calcite surface: Adsorption of Cd2+ and subsequent solid solution formation

    USGS Publications Warehouse

    Davis, J.A.; Fuller, C.C.; Cook, A.D.

    1987-01-01

    The rate of Cd2+ sorption by calcite was determined as a function of pH and Mg2+ in aqueous solutions saturated with respect to calcite but undersaturated with respect to CdCO3. The sorption is characterized by two reaction steps, with the first reaching completion within 24 hours. The second step proceeded at a slow and nearly constant rate for at least 7 days. The rate of calcite recrystallization was also studied, using a Ca2+ isotopic exchange technique. Both the recrystallization rate of calcite and the rate of slow Cd2+ sorption decrease with increasing pH or with increasing Mg2+. The recrystallization rate could be predicted from the number of moles of Ca present in the hydrated surface layer. A model is presented which is consistent with the rates of Cd2+ sorption and Ca2+ isotopic exchange. In the model, the first step in Cd2+ sorption involves a fast adsorption reaction that is followed by diffusion of Cd2+ into a surface layer of hydrated CaCO3 that overlies crystalline calcite. Desorption of Cd2+ from the hydrated layer is slow. The second step is solid solution formation in new crystalline material, which grows from the disordered mixture of Cd and Ca carbonate in the hydrated surface layer. Calculated distribution coefficients for solid solutions formed at the surface are slightly greater than the ratio of equilibrium constants for dissolution of calcite and CdCO3, which is the value that would be expected for an ideal solid solution in equilibrium with the aqueous solution. ?? 1987.

  20. Chloral hydrate

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 00 / 006 TOXICOLOGICAL REVIEW OF CHLORAL HYDRATE ( CAS No . 302 - 17 - 0 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) August 2000 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This document has been reviewed in accordance w

  1. The influence of inner hydrophobisation on water transport properties of modified lime plasters

    NASA Astrophysics Data System (ADS)

    Pavlíková, Milena; Pavlík, Zbyšek; Pernicová, Radka; Černý, Robert

    2016-06-01

    The effect of hydrophobic agent admixture on water vapour and liquid water transport properties of newly designed lime plasters is analysed in the paper. The major part of physico - chemical building deterioration is related to the penetration of moisture and soluble salts into the building structure. For that reason, the modified lime plasters were in the broad range of basic material properties tested. From the quantitative point of view, the measured results clearly demonstrate the big differences in the behaviour of studied materials depending on applied modifying admixtures. From the practical point of view, plaster made of lime hydrate, metakaolin, zinc stearate and air-entraining agent can be recommended for renovation purposes. The accessed material parameters will be used as input data for computational modelling of moisture transport in this type of porous building materials and will be stored in material database.

  2. Stabilities of calcite and aragonite

    USGS Publications Warehouse

    Christ, C.L.; Hostetler, P.B.; Siebert, R.M.

    1974-01-01

    A revaluation of the 25° C activity-product constants of calcite (KC) and aragonite (KA) was made on the basis of the known solubilities of these phases for which the activity of total dissolved calcium was corrected for the presence of the ion pair CaHCO3+ in the aqueous phase. The value of the dissociation constant of CaHCO3+ was taken to be 10-1.225±0.02. This value, combined with values of the analytical concentrations in solutions with partial pressure PCO2 =0.97 atmosphere, leads to KC=l0-8.52±0.04 and KA= 10-8.36±0.04. Based on these K values, standard free energies of formation of calcite and aragonite were calculated to be -270,144±375 and -269,926±375 calories mole-1, (-1,130,282±1,569 and -1,129,370±1,569 joules mole-1), respectively. From the 25°C K values, using appropriate entropy and heat capacity data, values of KC and KA were calculated over the temperature range 0° to 200°C. Possible errors in interpretation of measured pH values and inferred PCO2values and the bearing of these errors on calculations of K values are discussed.

  3. Lime application for the efficient production of nutraceutical glucooligosaccharides from Leuconostoc mesenteroides NRRL B-742 (ATCC13146).

    PubMed

    Moon, Young Hwan; Madsen, Lee; Chung, Chang-Ho; Kim, Doman; Day, Donal F

    2015-02-01

    We have previously demonstrated the production of glucooligosaccharides via a fermentation of sucrose with Leuconostoc mesenteroides NRRL B-742 using sodium hydroxide (NaOH) to control the pH. Because NaOH is expensive, we sought to minimize the cost of our process by substituting hydrated lime and saccharate of lime (lime sucrate) in its place. The yield of glucooligosaccharides using either 5 % lime (41.4 ± 0.5 g/100 g) or 5 % lime sucrate (40.0 ± 1.4 g/100 g) were both similar to the NaOH control (42.4 ± 1.5 g/100 g). Based on this, it appears that the cost associated with pH control in our process can be reduced by a factor of approximately 2.4 using lime instead of NaOH. Because our chromatographic stage is based on a Ca(2+)-form resin to separate glucooligosaccharides, the use of lime not only negates the need for costly de-salting via ion-exchange (elimination of two ion-exchange sections) prior to separation, but also greatly reduces the resin regeneration cost.

  4. Trace concentration - Huge impact: Nitrate in the calcite/Eu(III) system

    NASA Astrophysics Data System (ADS)

    Hofmann, Sascha; Voïtchovsky, Kislon; Schmidt, Moritz; Stumpf, Thorsten

    2014-01-01

    The interactions of trivalent lanthanides and actinides with secondary mineral phases such as calcite is of high importance for the safety assessment of deep geological repositories for high level nuclear waste (HLW). Due to similar ionic radii, calcium-bearing mineral phases are suitable host minerals for Ln(III) and An(III) ions. Especially calcite has been proven to retain these metal ions effectively by both surface complexation and bulk incorporation. Since anionic ligands (e.g., nitrate) are omnipresent in the geological environment and due to their coordinating properties, their influence on retentive processes should not be underestimated. Nitrate is a common contaminant in most HLW forms as a result of using nitric acid in fuel reprocessing. It is also formed by microbial activity under aerobic conditions. In this study, atomic force microscopy investigations revealed a major influence of nitrate upon the surface of calcite crystals. NaNO3 causes serious modifications even in trace amounts (<10-7 M) and forms a soft surface layer of low crystallinity on top of the calcite crystal. Time-resolved laser fluorescence spectroscopy of Eu(III) showed that, within this layer, Eu(III) ions are incorporated, while losing most of their hydration shell. The results show that solid solution modelling for actinides in calcite must take into account the presence of nitrate in pore and ground waters.

  5. Olefin hydration

    SciTech Connect

    Butt, M.H.D.; Waller, F.J.

    1993-08-03

    An improved process for the hydration of olefins to alcohols is described wherein the improvement comprises contacting said olefins with the catalytic composition comprising a perfluorinated ion-exchange polymer containing sulfonic acid groups supported on an inert carrier wherein said carrier comprises calcined shot coke with a mean pore diameter of about 1,000 Angstroms in the presence of water at a temperature of from about 180 C to about 250 C.

  6. Crystal lattice tilting in prismatic calcite.

    PubMed

    Olson, Ian C; Metzler, Rebecca A; Tamura, Nobumichi; Kunz, Martin; Killian, Christopher E; Gilbert, Pupa U P A

    2013-08-01

    We analyzed the calcitic prismatic layers in Atrina rigida (Ar), Haliotis iris (Hi), Haliotis laevigata (HL), Haliotis rufescens (Hrf), Mytilus californianus (Mc), Pinctada fucata (Pf), Pinctada margaritifera (Pm) shells, and the aragonitic prismatic layer in the Nautilus pompilius (Np) shell. Dramatic structural differences were observed across species, with 100-μm wide single-crystalline prisms in Hi, HL and Hrf, 1-μm wide needle-shaped calcite prisms in Mc, 1-μm wide spherulitic aragonite prisms in Np, 20-μm wide single-crystalline calcite prisms in Ar, and 20-μm wide polycrystalline calcite prisms in Pf and Pm. The calcite prisms in Pf and Pm are subdivided into sub-prismatic domains of orientations, and within each of these domains the calcite crystal lattice tilts gradually over long distances, on the order of 100 μm, with an angle spread of crystal orientation of 10-20°. Furthermore, prisms in Pf and Pm are harder than in any other calcite prisms analyzed, their nanoparticles are smaller, and the angle spread is strongly correlated with hardness in all shells that form calcitic prismatic layers. One can hypothesize a causal relationship of these correlated parameters: greater angle spread may confer greater hardness and resistance to wear, thus providing Pf and Pm with a structural advantage in their environment. This is the first structure-property relationship thus far hypothesized in mollusk shell prisms.

  7. Evidence for carbon sequestration by agricultural liming

    NASA Astrophysics Data System (ADS)

    Hamilton, Stephen K.; Kurzman, Amanda L.; Arango, Clay; Jin, Lixin; Robertson, G. Philip

    2007-06-01

    Agricultural lime can be a source or a sink for CO2, depending on whether reaction occurs with strong acids or carbonic acid. Here we examine the impact of liming on global warming potential by comparing the sum of Ca2+ and Mg2+ to carbonate alkalinity in soil solutions beneath unmanaged vegetation versus limed row crops, and of streams and rivers in agricultural versus forested watersheds, mainly in southern Michigan. Soil solutions sampled by tension indicated that lime can act as either a source or a sink for CO2. However, infiltrating waters tended to indicate net CO2 uptake, as did tile drainage waters and streams draining agricultural watersheds. As nitrate concentrations increased in infiltrating waters, lime switched from a net CO2 sink to a source, implying nitrification as a major acidifying process. Dissolution of lime may sequester CO2 equal to roughly 25-50% of its C content, in contrast to the prevailing assumption that all of the carbon in lime becomes CO2. The ˜30 Tg/yr of agricultural lime applied in the United States could thus sequester up to 1.9 Tg C/yr, about 15% of the annual change in the U.S. CO2 emissions (12 Tg C/yr for 2002-2003). The implications of liming for atmospheric CO2 stabilization should be considered in strategies to mitigate global climate change.

  8. Fly ash chemical classification based on lime

    SciTech Connect

    Fox, J.

    2007-07-01

    Typically, total lime content (CaO) of fly ash is shown in fly ash reports, but its significance is not addressed in US specifications. For certain applications a low lime ash is preferred. When a class C fly ash must be cementitious, lime content above 20% is required. A ternary S-A-C phase diagram pilot is given showing the location of fly ash compositions by coal rank and source in North America. Fly ashes from subbituminous coal from the Powder River Basin usually contain sufficient lime to be cementitious but blending with other coals may result in calcium being present in phases other than tricalcium aluminate. 9 refs., 1 fig.

  9. Lime for environmental uses. STP 931

    SciTech Connect

    Gutschick, K.A.

    1987-01-01

    This book STP 931 discusses the use of lime and industrial limestone for the control of factors that influence the environment - including the treatment of gaseous, liquid, and solid wastes. Current research shows that lime is one of the key chemicals that can help solve the problem of air, water, and land pollution. Topics covered are: the many environmental uses of lime including water treatment, sewage and industrial waste treatment, and the scrubbing of sulfur dioxide from power plant gases; various lime types and the engineering considerations in the design of lime handling systems; a hazardous waste incident where the waste was solidified with quicklime and lime kiln dust for burial; the growing use of lime and fly-ash for stabilizing scrubber sludges produced in wet scrubbing installations at more than 20 power plants in the United States; use of lime for stabilizing sewage sludge for land fill disposal; neutralization of calcium and magnesium calcium hydroxides through the use of carbon dioxide; and lime stabilization of expansive clays and silty clays for use in earth dams, irrigation canals, and levees.

  10. Hydrate habitat

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    Whoever said there is nothing new under the sun did not delve deeply enough to the bottom of the ocean. There in the Gulf of Mexico, about 150 miles south of New Orleans, scientists have just discovered what could be a new species of centipede—like worms living on or within gas hydrates— mounds of methane ice— rising from the ocean floor.Scientists have previously recognized an association between some bacteria and these hydrates. However, this is the first discovery of a higher life form there.

  11. Rehabilitating acid soils for increasing crop productivity through low-cost liming material.

    PubMed

    Bhat, Javid Ahmad; Kundu, Manik Chandra; Hazra, Gora Chand; Santra, Gour Hari; Mandal, Biswapati

    2010-09-15

    Productivity of red and lateritic soils is low because of their acidity and deficiencies in few essential nutrients viz., nitrogen, phosphorus, calcium, zinc, boron, molybdenum etc. We compared the effectiveness of basic slag, a low-cost liming material, with that of calcite as an ameliorant for these soils using mustard followed by rice as test crops. Experiments were conducted with three levels of each of basic slag and calcite along with a control on farmers' fields at 14 different locations. Influence of farmyard manure (FYM) and poultry manure (PM) on the effectiveness of the slag was also tested. On an average, basic slag performed better than calcite in increasing yields of both mustard and rice and left over higher amounts of available Ca, Si and Zn in residual soils. The slag also improved N, P, K and Ca nutrition of mustard and Si and Zn nutrition of rice with a favorable benefit:cost (B:C) ratio over the calcite (4.82 vs. 1.44). Effectiveness of the basic slag improved when it was applied in combination with FYM or PM (B:C, 5.83 and 6.27). Basic slag can, therefore, be advocated for use in the acidic red and lateritic soils for economically improving their productivity.

  12. PCM-enhanced lime plasters for vernacular and contemporary architecture

    NASA Astrophysics Data System (ADS)

    Theodoridou, Magdalini; Kyriakou, Loucas; Ioannou, Ioannis

    2016-04-01

    In 1997, the European Union (EU) pledged to reduce the amount of greenhouse gas emissions by 20% below the levels of 1990 by the end of 2020. In recent years it has become evident that, in order to reach that goal, EU Member States must take measures to encourage sustainability in the building industry, which is a major energy consumer. Such measures should involve the use of innovative, environmentally friendly materials and methods in new constructions, as well as the renovation of existing properties by upgrading their current state of energy efficiency. Phase Change Materials (PCMs) have the ability to absorb and release thermal energy, in the form of latent heat, during the melting or solidifying processes respectively. Thus, they may be used as additives in the production of thermally efficient composite building materials. A PCM-enhanced plaster is a heat storage medium combining an appropriate PCM with a cementitious or non-cementitious matrix to produce a low-cost thermal storage material with structural and thermostatic properties. Although innovative technologies, such as PCMs, have certainly contributed to the boost in the evolution of the building materials industry in recent years, a significant proportion of these technologies and practices have not yet been fully exploited in materials based on traditional principles. This paper focuses on the design and production of novel cementless PCM-enhanced lime plasters, in line with the traditional production technology of lime composites. The new plasters are produced using either hydrated or natural hydraulic lime binder, crushed calcarenite sand (0-2 mm) and commercial microencapsulated PCM in powder form (5% w/w of solids). Results from comparative tests between reference mixtures and mixtures with the addition of PCM, carried out 28, 56 and 90 days after laboratory production, prove the potential of PCMs in enhancing the thermal performance of traditional lime-based composites. The modified composites

  13. Alginic Acid Accelerates Calcite Dissolution

    NASA Astrophysics Data System (ADS)

    Perry, T. D.; Duckworth, O. W.; McNamara, C. J.; Martin, S. T.; Mitchell, R.

    2003-12-01

    Accelerated carbonate weathering through biological activity affects both geochemical cycling and the local pH and alkalinity of terrestrial and marine waters. Microbes affect carbonate dissolution through metabolic activity, production of acidic or chelating exudates, and cation binding by cell walls. Dissolution occurs within microbial biofilms - communities of microorganisms attached to stone in an exopolymer matrix. We investigated the effect of alginic acid, a common biological polymer produced by bacteria and algae, on calcite dissolution using a paired atomic force microscopy/flow-through reactor apparatus. The alginic acid caused up to an order of magnitude increase in dissolution rate at 3 < pH < 12. Additionally, the polymer preferentially binds to the obtuse pit steps and increases step velocity. We propose that the polymer is actively chelating surficial cations reducing the activation energy and increasing dissolution rate. The role of biologically produced polymers in mineral weathering is important in the protection of cultural heritage materials and understanding of marine and terrestrial systems.

  14. Do organic ligands affect calcite dissolution rates?

    NASA Astrophysics Data System (ADS)

    Oelkers, Eric H.; Golubev, Sergey V.; Pokrovsky, Oleg S.; Bénézeth, Pascale

    2011-04-01

    Steady state Iceland-spar calcite dissolution rates were measured at 25 °C in aqueous solutions containing 0.1 M NaCl and up to 0.05 M dissolved bicarbonate at pH from 7.9 to 9.1 in the presence of 13 distinct dissolved organic ligands in mixed-flow reactors. The organic ligands considered in this study include those most likely to be present in either (1) aquifers at the conditions pertinent to CO 2 sequestration or (2) soil/early diagenetic environments: acetate, phthalate, citrate, EDTA 4-, succinate, D-glucosaminate, L-glutamate, D-gluconate, 2,4-dihydroxybenzoate, 3,4-dihydroxybenzoate, fumarate, malonate, and gallate. Results show that the presence of <0.05 mol/kg of these organic anions changes calcite dissolution rates by less than a factor of 2.5 with the exception of citrate and EDTA 4-. The presence of 0.05 mol/kg citrate and EDTA 4- increases calcite dissolution rates by as much as a factor of 35 and 500, respectively, compared to rates in organic anion-free solutions. Further calcite dissolution experiments were performed in the presence of organic polymers similar to bacterial exudates, cell exopolysaccharides, and analogs of microbial cell envelopes: alginate, lichen extract, humic acid, pectin, and gum xanthan. In no case did the presence of <100 ppm of these organics change calcite dissolution rates by more than a factor of 2.5. Results obtained in this study suggest that the presence of aqueous organic anions negligibly affects calcite forward dissolution rates in most natural environments. Some effect on calcite reactivity may be observed, however, by the presence of organic anions if they change substantially the chemical affinity of the fluid with respect to calcite.

  15. Simple Analysis of Historical Lime Mortars

    ERIC Educational Resources Information Center

    Pires, Joa~o

    2015-01-01

    A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

  16. Effects of limestone petrography and calcite microstructure on OPC clinker raw meals burnability

    NASA Astrophysics Data System (ADS)

    Galimberti, Matteo; Marinoni, Nicoletta; Della Porta, Giovanna; Marchi, Maurizio; Dapiaggi, Monica

    2016-12-01

    Limestone represents the main raw material for ordinary Portland cement clinker production. In this study eight natural limestones from different geological environments were chosen to prepare raw meals for clinker manufacturing, aiming to define a parameter controlling the burnability. First, limestones were characterized by X-Ray Fluorescence, X-Ray Powder Diffraction and Optical Microscopy to assess their suitability for clinker production and their petrographic features. The average domains size and the microstrain of calcite were also determined by X-Ray Powder Diffraction line profile analysis. Then, each limestone was admixed with clay minerals to achieve the adequate chemical composition for clinker production. Raw meals were thermally threated at seven different temperatures, from 1000 to 1450 °C, to evaluate their behaviour on heating by ex situ X-Ray Powder Diffraction and to observe the final clinker morphology by Scanning Electron Microscopy. Results indicate the calcite microstrain is a reliable parameter to predict the burnability of the raw meals, in terms of calcium silicates growth and lime consumption. In particular, mixtures prepared starting from high-strained calcite exhibit a better burnability. Later, when the melt appears this correlation vanishes; however differences in the early burnability still reflect on the final clinker composition and texture.

  17. Diffusion of Ca and Mg in Calcite

    SciTech Connect

    Cygan, R.T.; Fisler, D.K.

    1999-02-10

    The self-diffusion of Ca and the tracer diffusion of Mg in calcite have been experimentally measured using isotopic tracers of {sup 25}Mg and {sup 44}Ca. Natural single crystals of calcite were coated with a thermally-sputtered oxide thin film and then annealed in a CO{sub 2} gas at one atmosphere total pressure and temperatures from 550 to 800 C. Diffusion coefficient values were derived from the depth profiles obtained by ion microprobe analysis. The resultant activation energies for Mg tracer diffusion and Ca self-diffusion are respectively: E{sub a}(Mg) = 284 {+-} 74 kJ/mol and E{sub a}(Ca) = 271 {+-} 80 kJ/mol. For the temperature ranges in these experiments, the diffusion of Mg is faster than Ca. The results are generally consistent in magnitude with divalent cation diffusion rates obtained in previous studies and provide a means of interpreting the thermal histories of carbonate minerals, the mechanism of dolomitization, and other diffusion-controlled processes. The results indicate that cation diffusion in calcite is relatively slow and cations are the rate-limiting diffusing species for the deformation of calcite and carbonate rocks. Application of the calcite-dolomite geothermometer to metamorphic assemblages will be constrained by cation diffusion and cooling rates. The direct measurement of Mg tracer diffusion in calcite indicates that dolomitization is unlikely to be accomplished by Mg diffusion in the solid state but by a recrystallization process.

  18. Impact of amorphous precursor phases on magnesium isotope signatures of Mg-calcite

    NASA Astrophysics Data System (ADS)

    Mavromatis, Vasileios; Purgstaller, Bettina; Dietzel, Martin; Buhl, Dieter; Immenhauser, Adrian; Schott, Jacques

    2017-04-01

    Various marine calcifiers form exoskeletons via an amorphous calcium carbonate (ACC) precursor phase and magnesium plays an important role in the temporary stabilization of this metastable phase. Thus, the use of Mg isotope ratios of marine biogenic carbonates as a proxy to reconstruct past seawater chemistry calls for a detailed understanding of the mechanisms controlling Mg isotope signatures during the formation and transformation of ACC to the final crystalline carbonate mineral. For this purpose we have investigated the Mg isotope fractionation between (Ca,Mg)CO3 solids and aqueous fluids at 25 °C and pH = 8.3 during (i) the direct precipitation of crystalline Mg-calcite and (ii) the formation of Mg-rich ACC (Mg-ACC) and its transformation to Mg-calcite. The outcome documents that the small Mg isotope fractionation between Mg-ACC and reactive fluid (ΔMg26ACC-fluid = - 1.0 ± 0.1 ‰) is not preserved during the transformation of the ACCs into Mg-calcite. Following a pronounced isotopic shift accompanying the transformation of Mg-ACC into Mg-calcite, Δ26Mgcalcite-fluid progressively decreases with reaction progress from ∼ - 3.0 ‰ to - 3.6 ‰, reflecting both the approach of isotopic equilibrium and the increase of calcite Mg content (to near 20 mol % Mg). In contrast the crystalline Mg-calcite precipitated directly from the reacting fluid, i.e. lacking a discernable formation of an amorphous precursor, exhibits only small temporal variations in Δ26Mgcalcite-fluid which overall is affected by the precipitation kinetics. The values found in this study at the onset of Mg-ACC precipitation for Mg isotope fractionation between Mg-ACC and the fluid (ΔMg26ACC-fluid = - 1.0 ‰) and between Mg-ACC and Mg2+(aq) (Δ(aq) 26 Mg ACC-Mg2+ = + 2.0 ‰) are consistent with the formation of a hydrated Ca nanoporous solid accommodating Mg bicarbonate/carbonate species in combination with hydrated magnesium. This material crossed by percolating channels filled with the

  19. Crystalline order of a water/glycine film coadsorbed on the (104) calcite surface.

    PubMed

    Magdans, Uta; Torrelles, Xavier; Angermund, Klaus; Gies, Hermann; Rius, Jordi

    2007-04-24

    For biomineralization processes, the interaction of the surface of calcite crystals with organic molecules is of particular importance. Especially, biologically controlled biomineralization as in exoskeletons of mollusks and echinoderms, e.g., sea urchin with single-crystal-like spines and shells,1-3 requires molecular control of seed formation and growth process. So far, experiments showing the obvious influence of organic molecules on the morphology and habit of calcite crystals have demonstrated the molecular dimension of the interaction.4-7 Details of the kinetics of growth and dissolution of mineral surfaces influenced by additives are available,8,9 but other experimental data about the structure of the organic/inorganic interface on the atomic scale are rare. On the other hand, complicated organic macromolecules which are involved in biomineralization are numerous, with only a small fraction solved in structure and function so far.10-13 Therefore, model systems have to be designed to provide a basic understanding for the interaction process.14 Using grazing incidence X-ray diffraction combined with molecular modeling techniques, we show that glycine molecules order periodically on the calcite (104) face in competition with the solvent water when exposed to an aqueous solution of the most simple amino acid. In contrast to the general concept of the charge-matching fit of organic molecules on mineral surfaces,4,14 glycine is not attached to the calcite surface directly but substitutes for water molecules in the second hydration layer.

  20. Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation

    PubMed Central

    Anderson, Catherine; Malambo, Dennis Hanjalika; Gonzalez Perez, Maria Eliette; Nobela, Happiness Ngwanamoseka; de Pooter, Lobke; Spit, Jan; Hooijmans, Christine Maria; van de Vossenberg, Jack; Greya, Wilson; Thole, Bernard; van Lier, Jules B.; Brdjanovic, Damir

    2015-01-01

    In this research, three faecal sludge sanitizing methods—lactic acid fermentation, urea treatment and lime treatment—were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m3 of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment. PMID:26528995

  1. Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation.

    PubMed

    Anderson, Catherine; Malambo, Dennis Hanjalika; Perez, Maria Eliette Gonzalez; Nobela, Happiness Ngwanamoseka; de Pooter, Lobke; Spit, Jan; Hooijmans, Christine Maria; de Vossenberg, Jack van; Greya, Wilson; Thole, Bernard; van Lier, Jules B; Brdjanovic, Damir

    2015-10-29

    In this research, three faecal sludge sanitizing methods-lactic acid fermentation, urea treatment and lime treatment-were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m³ of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment.

  2. Clathrate hydrates in nature.

    PubMed

    Hester, Keith C; Brewer, Peter G

    2009-01-01

    Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves.

  3. Calcite dissolution in two deep eutrophic lakes

    SciTech Connect

    Ramisch, F.; Dittrich, M.; Mattenberger, C.; Wehrli, B.; Wueest, A.

    1999-10-01

    The calcium cycle, in particular carbonate dissolution, was analyzed in two deep eutrophic lakes, Lago di Lugano (288 m maximum depth) and Sempachersee (87 m) located in Switzerland. A box model approach was used to calculate calcite dissolution in the water column and at the sediment-water interface based on various lake monitoring data such as sediment traps, sediment cores, water and pore-water interface based on various lake monitoring data such as sediment traps, sediment cores, water and pore-water analysis. A model for stationary conditions allowing the calculation of calcite dissolution in the water column for a given particle size distribution was developed. The relative values of the simulated flux were consistent with sediment trap observations. The best fit of the dissolution rate constant of sinking calcite in Lago di Lugano was on the same order of magnitude (3 {center{underscore}dot} 10{sup {minus}10} kg{sup 1/3} s{sup {minus}1}) as published laboratory values for this surface controlled process. Both lakes show a similar specific calcite precipitation rate of 170 g Ca m{sup {minus}2} a{sup {minus}1}. The diffusive flux across the sediment-water interface amounts to about 15 and 10% of total calcite precipitation in Sempachersee and Lago di Lugano, respectively. However, 61% of the precipitated calcite is dissolved in the water column of Lago di Lugano compared to only 13% in Sempachersee. These results point towards the importance of grain size distributions and settling times in stratified deep waters as the two most important factors determining calcite retention in sediments of hard water lakes.

  4. Marine Diagenesis of Shallow Marine Lime-Mud Sediments: Insights from dgrO18 and dgrC13 Data.

    PubMed

    Choquette, P W

    1968-09-13

    Shallow marine lime-mud sediments of the Ste. Genevieve Formation (Mississippian), in part of the Illinois Basin, underwent at least three diagenetic changes: (i) local dolomitization in seawater or a brine, producing dolostone having average deltaC(13) of +2.5 per mille and deltaO(18) of +1.9 per mille (versus PDB-1); (ii) more usually cementation of unreplaced CaCO(3), in intrasediment seawater, yielding isotopically marine lime mudstone mainly composed of calcite, 4-micron or finer, with deltaO(18) of from -1 to +1 per mille; (iii) later partial alteration of CaCO(3), in permeable dolomitic rocks, by isotopically "lighter" waters, to calcite with an estimated deltaO(18) of -10 per mille or less. Isotope data appraised by petrographic analysis thus suggest "submarine" cementation of these carbonates in shallow marine conditions.

  5. Arsenic removal in conjunction with lime softening

    DOEpatents

    Khandaker, Nadim R.; Brady, Patrick V.; Teter, David M.; Krumhansl, James L.

    2004-10-12

    A method for removing dissolved arsenic from an aqueous medium comprising adding lime to the aqueous medium, and adding one or more sources of divalent metal ions other than calcium and magnesium to the aqueous medium, whereby dissolved arsenic in the aqueous medium is reduced to a lower level than possible if only the step of adding lime were performed. Also a composition of matter for removing dissolved arsenic from an aqueous medium comprising lime and one or more sources of divalent copper and/or zinc metal ions.

  6. Lime-pozzolana mortars in Roman catacombs: composition, structures and restoration

    SciTech Connect

    Sanchez-Moral, Sergio; Soler, Vicente; Garcia-Guinea, Javier

    2005-08-01

    Analyses of microsamples collected from Roman catacombs and samples of lime-pozzolana mortars hardened in the laboratory display higher contents in carbonated binder than other subaerial Roman monuments. The measured environmental data inside the Saint Callistus and Domitilla catacombs show a constant temperature of 15-17 deg C, a high CO{sub 2} content (1700 to 3500 ppm) and a relative humidity close to 100%. These conditions and particularly the high CO{sub 2} concentration speed-up the lime calcitization roughly by 500% and reduce the cationic diffusion to form hydrous calcium aluminosilicates. The structure of Roman catacomb mortars shows (i) coarser aggregates and thicker beds on the inside, (ii) thin, smoothed, light and fine-grained external surfaces with low content of aggregates and (iii) paintings and frescoes on the outside. The observed high porosity of the mortars can be attributed to cracking after drying linked with the high binder content. Hardened lime lumps inside the binder denote low water/mortar ratios for slaking. The aggregate tephra pyroclasts rich in aluminosilicate phases with accessorial amounts of Ba, Sr, Rb, Cu and Pb were analysed through X-ray diffraction (XRD), electron microprobe analysis (EMPA) and also by environmental scanning electron microscopy (ESEM) to identify the size and distribution of porosity. Results support procedures using local materials, special mortars and classic techniques for restoration purposes in hypogeal backgrounds.

  7. Thorough investigation of the oxygen heterocyclic fraction of lime (Citrus aurantifolia (Christm.) Swingle) juice.

    PubMed

    Costa, Rosaria; Russo, Marina; De Grazia, Selenia; Grasso, Elisa; Dugo, Paola; Mondello, Luigi

    2014-04-01

    Reversed-phase-HPLC analysis by means of superficially porous silica particle columns (fused-core) was applied to the investigation of flavonoids, coumarins, and psoralens in lime juice samples. Hesperidin (367.0 ± 16.0 ppm) and eriocitrin (148.0 ± 7.9 ppm) were the most abundant flavonoids. Fifteen coumarins and furocoumarins were determined, including bergamottin (29.6 ± 1.1 ppm), 5-geranyloxy-7-methoxycoumarin (16.5 ± 0.6 ppm), and oxypeucedanin hydrate (9.9 ± 0.5 ppm) as predominant compounds. These molecules are today well known for their beneficial effects on human health. As a consequence, the present study, beyond investigating for the first time the chemical composition of lime juice, highlights also its health-promoting qualities, due to its content of flavonoids and coumarins.

  8. Characterization of a lime-pozzolan plaster containing phase change material

    SciTech Connect

    Pavlíková, Milena; Pavlík, Zbyšek; Trník, Anton; Pokorný, Jaroslav; Černý, Robert

    2015-03-10

    A PCM (Phase Change Material) modified lime-pozzolan plaster for improvement of thermal energy storage of building envelopes is studied in the paper. The investigated plaster is composed of lime hydrate, pozzolan admixture based on metakaolin and mudstone, silica sand, water and paraffin wax encapsulated in polymer capsule. The reference plaster without PCM application is studied as well. The analyzed materials are characterized by bulk density, matrix density, total open porosity, compressive strength and pore size distribution. The temperature of phase change, heat of fusion and crystallization are studied using DSC (Difference Scanning Calorimetry) analysis performed in air atmosphere. In order to get information on materials hygrothermal performance, determination of thermal and hygric properties is done in laboratory conditions. Experimental data reveal a substantial improvement of heat storage capacity of PCM-modified plaster as compared to the reference material without PCM.

  9. Lime or lime:fly ash pretreated pavement construction material and method

    SciTech Connect

    Gnaedinger, J.P.

    1985-01-29

    A composition for use as a base course in a pavement construction is prepared by prereacting uncompacted incinerator ash with 2-10% by weight lime or 2-10% by weight of a 2:3 lime:fly ash mixture for several days and then adding 2-10% by weight lime and 20-25% by weight water to the composition before compaction.

  10. The Alkaline Dissolution Rate of Calcite.

    PubMed

    Colombani, Jean

    2016-07-07

    Due to the widespread presence of calcium carbonate on Earth, several geochemical systems, among which is the global CO2 cycle, are controlled to a large extent by the dissolution and precipitation of this mineral. For this reason, the dissolution of calcite has been thoroughly investigated for decades. Despite this intense activity, a consensual value of the dissolution rate of calcite has not been found yet. We show here that the inconsistency between the reported values stems mainly from the variability of the chemical and hydrodynamic conditions of measurement. The spreading of the values, when compared in identical conditions, is much less than expected and is interpreted in terms of sample surface topography. This analysis leads us to propose benchmark values of the alkaline dissolution rate of calcite compatible with all the published values, and a method to use them in various chemical and hydrodynamic contexts.

  11. New Origins of the Vital Effect in Calcites: Mg-Enhancing Influence of Biomolecules

    NASA Astrophysics Data System (ADS)

    Stephenson, A. E.; Wu, L.; Wu, K. J.; Deyoreo, J. J.; Dove, P. M.

    2007-12-01

    Owing to the intense interest in the compositional signatures of biominerals, the mechanistic basis for vital effects and their roles in modifying or masking impurity contents are receiving increasing scrutiny. To date, much of the effort has been focused on the influence of physical environment and inorganic chemical factors. In a recent study that investigated the effects of acidic proteins on calcite growth, our research group found that nanomolar concentratios of acidic amino acids, peptides, and full proteins accelerate the rate of mineral formation by a relationship that correlates with the acidity (hydrophilicity) of the biomolecule (Elhadj et al., 2006, PNAS). Experimental and theoretical evidence suggest that the measured rate-enhancing effect (up to 25X) arises from weak interactions of the biomolecule with the calcite surface to alter the local solvation environment. This relation suggests that the acidic macromolecules that have been isolated from diverse calcifying taxa may have yet unrecognized effects on mineralization. Because Mg has a strong hydration shell relative to Ca, we hypothesized that the presence of these rate-modifying peptides in growth solutions would also lower the barrier to incorporating Mg, and thereby increase the MgCO3 content of calcite overgrowths. To test this idea, measurements of calcite growth rate were made using Atomic Force Microscopy, and in the presence or absence of acidic, hydrophilic 27-mer peptides. The peptide increased the growth rate of obtuse flanks (42% faster, on average, and up to 92% faster) and acute flanks (17% faster on average; up to 54% faster). The calcite overgrowths from AFM experiments were then analyzed for corresponding MgCO3 compositions by Time-of-Flight Secondary Ion Mass Spectrometry. The data yield an inorganic baseline that quantifies the relation between Mg content and the solution concentration. Comparisons of the baseline Mg content to that of peptide-enriched overgrowths show the MgCO3

  12. Recycled sand in lime-based mortars.

    PubMed

    Stefanidou, M; Anastasiou, E; Georgiadis Filikas, K

    2014-12-01

    The increasing awareness of the society about safe guarding heritage buildings and at the same time protecting the environment promotes strategies of combining principles of restoration with environmentally friendly materials and techniques. Along these lines, an experimental program was carried out in order to investigate the possibility of producing repair, lime-based mortars used in historic buildings incorporating secondary materials. The alternative material tested was recycled fine aggregates originating from mixed construction and demolition waste. Extensive tests on the raw materials have been performed and mortar mixtures were produced using different binding systems with natural, standard and recycled sand in order to compare their mechanical, physical and microstructure properties. The study reveals the improved behavior of lime mortars, even at early ages, due to the reaction of lime with the Al and Si constituents of the fine recycled sand. The role of the recycled sand was more beneficial in lime mortars rather than the lime-pozzolan or lime-pozzolan-cement mortars as a decrease in their performance was recorded in the latter cases due to the mortars' structure.

  13. Removal of strontium from drinking water by conventional treatment and lime softening in bench-scale studies.

    PubMed

    O'Donnell, Alissa J; Lytle, Darren A; Harmon, Stephen; Vu, Kevin; Chait, Hannah; Dionysiou, Dionysios D

    2016-10-15

    The United States Environmental Protection Agency Contaminant Candidate List 3 lists strontium as a contaminant for potential regulatory consideration in drinking water. Very limited data is available on strontium removal from drinking water and as a result, there is an immediate need for treatment information. The objective of this work is to evaluate the effectiveness of coagulation/filtration and lime-soda ash softening treatment methods to remove strontium from surface and ground waters. Coagulation/filtration jar test results on natural waters showed that conventional treatment with aluminum and iron coagulants were able to achieve only 12% and 5.9% strontium removal, while lime softening removed as high as 78% from natural strontium-containing ground water. Controlled batch experiments on synthetic water showed that strontium removal during the lime-soda ash softening was affected by pH, calcium concentration and dissolved inorganic carbon concentration. In all softening jar tests, the final strontium concentration was directly related to the initial strontium concentration and the removal of strontium was directly associated with calcium removal. Precipitated solids showed well-formed crystals or agglomerates of mixed solids, two polymorphs of calcium carbonate (vaterite and calcite), and strontianite, depending on initial water quality conditions. X-ray diffraction analysis suggested that strontium was likely incorporated in the calcium carbonate crystal lattice and was likely responsible for removal during lime softening.

  14. Interaction of alcohols with the calcite surface.

    PubMed

    Bovet, N; Yang, M; Javadi, M S; Stipp, S L S

    2015-02-07

    A clearer understanding of calcite interactions with organic molecules would contribute to a range of fields including harnessing the secrets of biomineralisation where organisms produce hard parts, increasing oil production from spent reservoirs, remediating contaminated soils and drinking water aquifers and improving manufacturing methods for industrial products such as pigments, soft abrasives, building materials and optical devices. Biomineralisation by some species of blue green algae produces beautifully elaborate platelets of calcite where the individual crystals are of nanometer scale. Controlling their growth requires complex polysaccharides. Polysaccharide activity depends on the functionality of OH groups, so to simplify the system in order to get closer to a molecular level understanding, we investigated the interaction of OH from a suite of alcohols with clean, freshly cleaved calcite surfaces. X-ray photoelectron spectroscopy (XPS) provided binding energies and revealed the extent of surface coverage. Molecular dynamics (MD) simulations supplemented with information about molecule ordering, orientation and packing density. The results show that all alcohols studied bond with the calcite surface through the OH group, with their carbon chains sticking away in a standing-up orientation. Alcohol molecules are closely packed and form a well-ordered monolayer on the surface.

  15. Cyclic Cratonic Carbonates and Phanerozoic Calcite Seas.

    ERIC Educational Resources Information Center

    Wilkinson, Bruce H.

    1982-01-01

    Discusses causes of cyclicity in cratonic carbonate sequences and evidence for and potential significance of postulated primary calcite sediment components in past Paleozoic seas, outlining problems, focusing on models explaining existing data, and identifying background. Future sedimentary geologists will need to address these and related areas…

  16. Alternate deposition of oriented calcite and amino acid layer on calcite substrates.

    PubMed

    Qiao, Li; Feng, Qingling; Li, Zhuo; Lu, Shanshan

    2008-10-30

    Material synthesis inspired by novel nacre architecture and mechanism is popular and has attracted more and more attention. In this paper, iso-oriented calcite tablets/layers and amino acid layers were formed alternately on calcite wafers. It is interesting that the neonatal calcite tablets/layers have the same crystal orientation with their inorganic substrates through amino acid layers. It is quite possible that the amino acid layers in this study could transfer crystal orientation from formed inorganic layers to neighboring neonatal layers due to their fixed and appropriate structures, which may imply the process of nacre formation, and the role of aligned organic matrix sheets in nacre. Moreover, it could provide a new way to produce oriented calcite tablets/layers.

  17. Planktic Foraminiferal Sedimentation and Calcite Budget

    NASA Astrophysics Data System (ADS)

    Schiebel, R.

    2002-12-01

    Vertical flux and sedimentation rate of planktic foraminiferal tests is quantified on a global scale. The planktic foraminiferal test flux is a consequence of the population dynamics, and the differential settling modes for different species are a precondition for the differences in the regional flux rates. The average planktic foraminiferal calcite flux rate at the 100-m depth-level is estimated at 50% of the global-marine calcite flux and 6% of the total carbon flux. The most significant decrease in the planktic foraminiferal test flux rates between 100-700 m water depth possibly results from increased bacterially-mediated decomposition of cytoplasm and a decreasing pH in microenvironments within foraminiferal tests. Throughout most of the year, on average only 1-3% of the initially exported CaCO3 reaches the deep sea floor. Pulsed flux events, mass dumps of fast settling particles, yield a major contribution of tests to the formation of deep-sea sediments. On a global average, ~25% of the total calcite produced by planktic foraminifers arrives in the deep ocean and at the sediment surface. To complete the open-marine, particulate CaCO3 inventory, the contribution of coccolithophores, pteropods, and calcareous dinophytes is discussed. The global planktic foraminiferal calcite flux rate at 100 m depth amounts to 23-56% of the total open marine CaCO3 flux. The total planktic foraminiferal contribution of CaCO3 to global surface sediments is estimated at 0.36-0.88 Gt per year, ~30-80% of the total deep-marine calcite budget.

  18. Improved control of sucrose losses and clarified juice turbidity with lime saccharate in hot lime clarification of sugarcane juice and other comparisons with milk of lime

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A comparative investigation of adding milk of lime (MOL) versus lime saccharate (SACCH) in hot lime clarification of juice at a U.S. sugarcane factory was undertaken to quantify performance across the 2009 processing season after a preliminary factory study in 2008. SACCH was prepared by adding hyd...

  19. Effect of whole catchment liming on the episodic acidification of two adirondack streams

    USGS Publications Warehouse

    Newton, R.M.; Burns, Douglas A.; Blette, V.L.; Driscoll, C.T.

    1996-01-01

    During the fall of 1989 7.7Mg/ha of calcium carbonate was applied on two tributary catchments (40 ha and 60 ha) to Woods Lake, a small (25 ha) acidic headwater lake in the western Adirondack region of New York. Stream-water chemistry in both catchment tributaries responded immediately. Acid-neutralizing capacity (ANC) increased by more than 200 ??eq/L in one of the streams and more than 1000 ??eq/L in the other, from pre-liming values which ranged from -25 to +40 ??eq/L. The increase in ANC was primarily due to increases in dissolved Ca2+ concentrations. Most of the initial response of the streams was due to the dissolution of calcite that fell directly into the stream channels and adjacent wetlands. A small beaver impoundment and associated wetlands were probably responsible for the greater response observed in one of the streams. After the liming of subcatchmentIV (60 ha), Ca2+ concentrations increased with increasing stream discharge in the stream during fall rain events, suggesting a contribution from calcite dissolved within the soil and transported to the stream by surface runoff or shallow interflow. Concentrations of other ions not associated with the calcite (e.g. Na+) decreased during fall rain events, presumably due to mixing of solute-rich base flow with more dilute shallow interflow. The strong relation between changes in Ca2+ and changes in NO3- concentrations during spring snowmelt, (r2 = 0.93, slope = 0.96, on an equivalent basis) suggests that both solutes had a common source in the organic horizon of the soil. Increases in NO3- concentrations during snowmelt were balanced by increases in Ca2+ that was released either directly from the calcite or from exchange sites, mitigating episodic acidification of the stream. However, high ambient NO3- concentrations and relatively low ambient Ca2+ concentrations in the stream during the spring caused the stream to become acidic despite the CaCO3 treatment. In stream WO2 (40ha), Ca2+ concentrations were much

  20. in situ Calcite Precipitation for Contaminant Immobilization

    SciTech Connect

    Yoshiko Fujita; Robert W. Smith

    2009-08-01

    in situ Calcite Precipitation for Contaminant Immobilization Yoshiko Fujita (Yoshiko.fujita@inl.gov) (Idaho National Laboratory, Idaho Falls, Idaho, USA) Robert W. Smith (University of Idaho-Idaho Falls, Idaho Falls, Idaho, USA) Subsurface radionuclide and trace metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOE’s greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent trace ions, such as the short-lived radionuclide strontium-90, is co-precipitation in calcite. Calcite, a common mineral in the arid western U.S., can form solid solutions with trace metals. The rate of trace metal incorporation is susceptible to manipulation using either abiotic or biotic means. We have previously demonstrated that increasing the calcite precipitation rate by stimulating the activity of urea hydrolyzing microorganisms can result in significantly enhanced Sr uptake. Urea hydrolysis causes the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity, and also by liberating the reactive cations from the aquifer matrix via exchange reactions involving the ammonium ion derived from urea: H2NCONH2 + 3H2O ? 2NH4+ + HCO3- + OH- urea hydrolysis >X:2Ca + 2NH4+ ? 2>X:NH4 + Ca2+ ion exchange Ca2+ + HCO3- + OH- ? CaCO3(s) + H2O calcite precipitation where >X: is a cation exchange site on the aquifer matrix. This contaminant immobilization approach has several attractive features. Urea hydrolysis is catalyzed by the urease enzyme, which is produced by many indigenous subsurface microorganisms. Addition of foreign microbes is unnecessary. In turn the involvement of the native microbes and the consequent in situ generation of reactive components in the aqueous phase (e.g., carbonate and Ca or Sr) can allow dissemination of the reaction over a larger volume and/or farther away from an amendment injection point, as compared to direct addition of the reactants at

  1. Gas hydrate and humans

    USGS Publications Warehouse

    Kvenvolden, K.A.

    2000-01-01

    The potential effects of naturally occurring gas hydrate on humans are not understood with certainty, but enough information has been acquired over the past 30 years to make preliminary assessments possible. Three major issues are gas hydrate as (1) a potential energy resource, (2) a factor in global climate change, and (3) a submarine geohazard. The methane content is estimated to be between 1015 to 1017 m3 at STP and the worldwide distribution in outer continental margins of oceans and in polar regions are significant features of gas hydrate. However, its immediate development as an energy resource is not likely because there are various geological constraints and difficult technological problems that must be solved before economic recovery of methane from hydrate can be achieved. The role of gas hydrate in global climate change is uncertain. For hydrate methane to be an effective greenhouse gas, it must reach the atmosphere. Yet there are many obstacles to the transfer of methane from hydrate to the atmosphere. Rates of gas hydrate dissociation and the integrated rates of release and destruction of the methane in the geo/hydro/atmosphere are not adequately understood. Gas hydrate as a submarine geohazard, however, is of immediate and increasing importance to humans as our industrial society moves to exploit seabed resources at ever-greater depths in the waters of our coastal oceans. Human activities and installations in regions of gas-hydrate occurrence must take into account the presence of gas hydrate and deal with the consequences of its presence.

  2. Dissolution Kinetics of Biogenic Magnesian Calcites

    NASA Astrophysics Data System (ADS)

    Thompson, R.; Guidry, M.; Mackenzie, F. T.; De Carlo, E. H.

    2014-12-01

    Ocean acidification (OA) is a serious concern for the health of calcifying ecosystems in the near future. During the past century, surface ocean pH has decreased by ~0.1 pH units, and is expected to decrease further by 0.3-0.4 pH units by the end of this century. The process of OA will likely result in both decreased calcification rates and increased rates of carbonate mineral dissolution, particularly involving the magnesian calcite (Mg-calcite) calcifiers found in shallow-water reef and other carbonate environments. Many Mg-calcite compositions are the most soluble of the carbonate phases commonly found in reef environments (often comprising much of the cementation and structure within a reef), and are therefore potentially the most susceptible to dissolution processes associated with OA. However, the dissolution kinetics of these phases is poorly known, limiting our ability to understand their behavior in nature. Laboratory experiments designed to investigate the mechanisms and dissolution rates of biogenic Mg-calcite mineral phases in distilled water and seawater over a range of CO2 and T conditions were conducted employing both batch and fluidized-bed reactor systems and using a variety of cleaned and annealed biogenic Mg-calcite phases. Our initial results have shown that the dissolution rate at 298 K and a pCO2 of ~350 ppm of the crustose coralline alga Amphiroa rigida (~20 mol% MgCO3) in seawater undersaturated with respect to this phase is 3.6 μmol g-1 hr-1, nearly 50% greater than that under similar conditions for aragonite. This rate and the derived experimental rate law are consistent with the preliminary findings of Walter and Morse (1985). Additional kinetic (and also solubility) data will be presented for the following species: Chiton tuberculatus (~0-4 mol% MgCO3); Echinometra mathei and/or Lytechinus variegatus (~8-12 mol% MgCO3); Homotrema rubrum (12-16 mol% MgCO3); and Lithothamnion sp. (~18-24 mol% MgCO3). Quantification of the rates of

  3. Authigenic carbonates from the Cascadia subduction zone and their relations to gas hydrate stability

    SciTech Connect

    Bohrmann, G.; Greinert, J.; Suess, E.; Torres, M.

    1998-07-01

    Authigenic carbonates are intercalated with massive gas hydrates in sediments of the Cascadia margin. The deposits were recovered from the uppermost 50 cm of sediments on the southern summit of the Hydrate Ridge during the RV Sonne cruise SO110. Two carbonate lithologies that differ in chemistry, mineralogy, and fabric make up these deposits. Microcrystalline high-magnesium calcite (14 to 19 mol% MgCO{sub 3}) and aragonite are present in both semiconsolidated sediments and carbonate-cemented clasts. Aragonite occurs also as a pure phase without sediment impurities. It is formed by precipitation in cavities as botryoidal and isopachous aggregates within pure white, massive gas hydrate. Variations in oxygen isotope values of the carbonates reflect the mineralogical composition and define two end members: a Mg-calcite with {delta}{sup 18}O = 4.86% PDB and an aragonite with {delta}{sup 18}O = 3.68% PDB. On the basis of the ambient bottom-water temperature and accepted equations for oxygen isotope fractionation, the authors show that the aragonite phase formed in equilibrium with its pore-water environment, and that the Mg-calcite appears to have precipitated from pore fluids enriched in {sup 18}O. Oxygen isotope enrichment probably originates from hydrate water released during gas-hydrate destabilization.

  4. Calcite growth-rate inhibition by fulvic acid and magnesium ion—Possible influence on biogenic calcite formation

    NASA Astrophysics Data System (ADS)

    Reddy, Michael M.

    2012-08-01

    Increases in ocean surface water dissolved carbon dioxide (CO2) concentrations retard biocalcification by reducing calcite supersaturation (Ωc). Reduced calcification rates may influence growth-rate dependent magnesium ion (Mg) incorporation into biogenic calcite modifying the use of calcifying organisms as paleoclimate proxies. Fulvic acid (FA) at biocalcification sites may further reduce calcification rates. Calcite growth-rate inhibition by FA and Mg, two common constituents of seawater and soil water involved in the formation of biogenic calcite, was measured separately and in combination under identical, highly reproducible experimental conditions. Calcite growth rates (pH=8.5 and Ωc=4.5) are reduced by FA (0.5 mg/L) to 47% and by Mg (10-4 M) to 38%, compared to control experiments containing no added growth-rate inhibitor. Humic acid (HA) is twice as effective a calcite growth-rate inhibitor as FA. Calcite growth rate in the presence of both FA (0.5 mg/L) and Mg (10-4 M) is reduced to 5% of the control rate. Mg inhibits calcite growth rates by substitution for calcium ion at the growth site. In contrast, FA inhibits calcite growth rates by binding multiple carboxylate groups on the calcite surface. FA and Mg together have an increased affinity for the calcite growth sites reducing calcite growth rates.

  5. Calcite growth-rate inhibition by fulvic acid and magnesium ion—Possible influence on biogenic calcite formation

    USGS Publications Warehouse

    Reddy, Michael M.

    2012-01-01

    Increases in ocean surface water dissolved carbon dioxide (CO2) concentrations retard biocalcification by reducing calcite supersaturation (Ωc). Reduced calcification rates may influence growth-rate dependent magnesium ion (Mg) incorporation into biogenic calcite modifying the use of calcifying organisms as paleoclimate proxies. Fulvic acid (FA) at biocalcification sites may further reduce calcification rates. Calcite growth-rate inhibition by FA and Mg, two common constituents of seawater and soil water involved in the formation of biogenic calcite, was measured separately and in combination under identical, highly reproducible experimental conditions. Calcite growth rates (pH=8.5 and Ωc=4.5) are reduced by FA (0.5 mg/L) to 47% and by Mg (10−4 M) to 38%, compared to control experiments containing no added growth-rate inhibitor. Humic acid (HA) is twice as effective a calcite growth-rate inhibitor as FA. Calcite growth rate in the presence of both FA (0.5 mg/L) and Mg (10−4 M) is reduced to 5% of the control rate. Mg inhibits calcite growth rates by substitution for calcium ion at the growth site. In contrast, FA inhibits calcite growth rates by binding multiple carboxylate groups on the calcite surface. FA and Mg together have an increased affinity for the calcite growth sites reducing calcite growth rates.

  6. Fabrication of interconnected porous calcite by bridging calcite granules with dicalcium phosphate dihydrate and their histological evaluation.

    PubMed

    Ishikawa, Kunio; Koga, Noriko; Tsuru, Kanji; Takahashi, Ichiro

    2015-10-28

    Interconnected porous calcite has attracted attention as an artificial bone replacement material and as a precursor for the fabrication of carbonate apatite, which is also an artificial bone replacement material. In this study, calcite granules were exposed to acidic calcium phosphate solution, and the feasibility of fabricating interconnected porous calcite using this process was evaluated. No setting reaction was observed under the non-loading condition. In contrast, under loading conditions, calcite granules were bridged with dicalcium phosphate dihydrate crystals, and the calcite granules set into interconnected porous calcite foam. When applied 0.4 MPa of loading pressure during sample preparation, compressive strength of the obtained interconnected porous calcite was approximately 1.5 MPa. The exposure of the calcite granules to acidic calcium phosphate solution under loading conditions was the key for the setting reaction to occur. This is because calcite granules cannot contact one another under the non-loading condition because of bubble formation on the surfaces of the calcite granules. The interconnected porous calcite revealed excellent tissue response, and new bone was able to penetrate into the porous calcite two weeks after implantation. This article is protected by copyright. All rights reserved.

  7. Magnesian calcite sorbent for carbon dioxide capture.

    PubMed

    Mabry, James C; Mondal, Kanchan

    2011-01-01

    Magnesian calcite with controlled properties was synthesized for the removal of carbon dioxide. The results from characterization, reactivity and CO2 capture capacity for different synthesis conditions are reported. The magnesian calcite samples (CaCO3:MgCO3) were synthesized by the coprecipitation of specific amounts of commercially available CaO and MgO by carbon dioxide. Characterization was done with BET, SEM/EDS, particle size analysis and XRD. The capacity was measured using TGA cycles at 800 degrees C and compared for different preparation conditions. The effects of CaO, MgO and surfactant loading on the physical properties and carbonation activity were studied to determine the optimal synthesis condition. A long-term carbonation-calcination cycling test was conducted on the optimal sample. It was observed that the sample maintained its capacity to 86% of its original uptake even after 50 cycles.

  8. Frictional behavior of talc-calcite mixtures

    NASA Astrophysics Data System (ADS)

    Giorgetti, C.; Carpenter, B. M.; Collettini, C.

    2015-09-01

    Faults involving phyllosilicates appear weak when compared to the laboratory-derived strength of most crustal rocks. Among phyllosilicates, talc, with very low friction, is one of the weakest minerals involved in various tectonic settings. As the presence of talc has been recently documented in carbonate faults, we performed laboratory friction experiments to better constrain how various amounts of talc could alter these fault's frictional properties. We used a biaxial apparatus to systematically shear different mixtures of talc and calcite as powdered gouge at room temperature, normal stresses up to 50 MPa and under different pore fluid saturated conditions, i.e., CaCO3-equilibrated water and silicone oil. We performed slide-hold-slide tests, 1-3000 s, to measure the amount of frictional healing and velocity-stepping tests, 0.1-1000 µm/s, to evaluate frictional stability. We then analyzed microstructures developed during our experiments. Our results show that with the addition of 20% talc the calcite gouge undergoes a 70% reduction in steady state frictional strength, a complete reduction of frictional healing and a transition from velocity-weakening to velocity-strengthening behavior. Microstructural analysis shows that with increasing talc content, deformation mechanisms evolve from distributed cataclastic flow of the granular calcite to localized sliding along talc-rich shear planes, resulting in a fully interconnected network of talc lamellae from 20% talc onward. Our observations indicate that in faults where talc and calcite are present, a low concentration of talc is enough to strongly modify the gouge's frictional properties and specifically to weaken the fault, reduce its ability to sustain future stress drops, and stabilize slip.

  9. Neptunium(V) coprecipitation with calcite.

    PubMed

    Heberling, Frank; Denecke, Melissa A; Bosbach, Dirk

    2008-01-15

    Coprecipitation experiments of Np(V) and U(VI) with calcite were performed in mixed-flow reactors under steady state conditions at room temperature for up to 400 h at precipitation rates of 1.0 x 10(-8) to 6.8 x 10(-8) mol/(m2 s). The saturation index with respect to calcite varied between 0.04 and 0.95. Initial Np(V) or U(VI) concentrations were 1 micromol/L, 0.01 mol/L NaCl was used as background electrolyte, and pH ranged from 7.8 to 12.8. Partition coefficients for Np(V) were in the range of 0.5-10.3, compared to 0.02 for U(VI). Np L(III) and U L(III) EXAFS were used to characterize the local structural environment of the incorporated actinides. In the case of U(VI), the structural environment is not unambiguously characterized. Our data suggest that Np(V) ions occupy calcium lattice sites. The two axial oxygen atoms of the linear neptunyl moiety substitute two calcite carbonate groups in the first coordination sphere. Thus, four carbonate groups coordinate the neptunyl-ion in a monodentate fashion with four equatorial oxygen atoms (Oeq) at 2.4 A and associated carbon atoms (C) at 3.2 A. The interatomic distances indicate slight structural relaxation of the carbonate groups from their ideal sites. A similar structural model has been reported for U(VI) incorporated into natural calcite.

  10. VIEW OF LIME KILN BUILDING LOOKING NORTHWEST, SHOWING STONE ELEVATOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF LIME KILN BUILDING LOOKING NORTHWEST, SHOWING STONE ELEVATOR (ON THE LEFT) AND SOUTH CONVEYOR. - Solvay Process Company, Lime Kiln Building, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  11. VIEW OF MLT BUILDING (LIME KILN BUILDING DIRECTLY BEHIND IT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF MLT BUILDING (LIME KILN BUILDING DIRECTLY BEHIND IT WITH GOOD VIEW OF SKIP CAR TRACK) LOOKING EAST. - Solvay Process Company, Lime Kiln Building, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  12. 62. INTERIOR VIEW OF THE LIME KILN BUILDING, LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    62. INTERIOR VIEW OF THE LIME KILN BUILDING, LOOKING AT THE LIME KILNS AND MOTOR DRIVES FOR THE KILNS. (DATE UNKNOWN). - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL

  13. LIME KILN BUILDING, KILN BOTTOM SHOWING ROTATOR GEAR. (GEAR IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LIME KILN BUILDING, KILN BOTTOM SHOWING ROTATOR GEAR. (GEAR IS POINTED DOWN FOR PROPER ORIENTATION). - Solvay Process Company, Lime Kiln Building, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  14. 19. LOOKING NORTH ALONG ROAD BISECTING SITE; PEBBLE LIME SILO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. LOOKING NORTH ALONG ROAD BISECTING SITE; PEBBLE LIME SILO ON THE RIGHT, MAIN SUPPLY BUILDING AND MACHINE SHOP ON THE LEFT. - Standard Lime & Stone Quarry, County Route 27, Millville, Jefferson County, WV

  15. VIEW OF TUNNEL TO MLT BUILDING UNDER LIME KILNS. CONVEYOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF TUNNEL TO MLT BUILDING UNDER LIME KILNS. CONVEYOR MOVES HOT STONE TO MLT'S. THIS IS THE DRIVE END OF CONVEYOR BELT. - Solvay Process Company, Milk of Lime Towers Building, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  16. VIEW OF TUNNEL TO MLT BUILDING UNDER LIME KILNS, CONVEYOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF TUNNEL TO MLT BUILDING UNDER LIME KILNS, CONVEYOR MOVES HOT STONE TO MLT'S (CONVEYOR ON RIGHT). - Solvay Process Company, Milk of Lime Towers Building, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  17. Gas Hydrate Nucleation Processes

    NASA Astrophysics Data System (ADS)

    David, R. E.; Zatsepina, O.; Phelps, T. J.

    2003-12-01

    The onset of gas hydrate nucleation is greatly affected by the thermal history of the water that forms its lattice structure. Hydrate formation experiments were performed in a 72 liter pressure vessel by bubbling carbon dioxide through a 1 liter column at hydrate formation pressures (1.4 to 3.7 MPa) and temperatures (275.0 to 278.0 K) to quantify this effect. They show that when even a fraction ( e. g. 20 %) of the water in which hydrate has formed was recently frozen and thawed, the overpressurization for nucleation was reduced by an average of 50 % versus experiments performed in distilled water. In those experiments where a lower overpressure is present when hydrate nucleated, they tended to form on the surface of bubbles, whereas when a higher amount of overpressure was necessary for hydrate to nucleate, they appeared to form abruptly on bubble surfaces as well as from the bulk liquid phase. In approximation of classical nucleation, hydrate formation could be described as occurring by the spontaneous joining together of arising components of the hydrate lattice. In water that was frozen, and kept at a low temperature (< 275 K), molecular simulation models predict the predominance of water molecules organized as penatmeters, a possible subunit of the hydrate lattice. Our results suggest that in nature, initiation of hydrate formation may be strongly influenced by temperature dependant pre-structuring of water molecules prior to their contact with gas.

  18. Low Temperature Synthesis of Belite Cement Based on Silica Fume and Lime

    PubMed Central

    Tantawy, M. A.; Shatat, M. R.; El-Roudi, A. M.; Taher, M. A.; Abd-El-Hamed, M.

    2014-01-01

    This paper describes the low temperature synthesis of belite (β-C2S) from silica fume. Mixtures of lime, BaCl2, and silica fume with the ratio of (Ca + Ba)/Si = 2 were hydrothermally treated in stainless steel capsule at 110–150°C for 2–5 hours, calcined at 600–700°C for 3 hours, and analyzed by FTIR, XRD, TGA/DTA, and SEM techniques. Dicalcium silicate hydrate (hillebrandite) was prepared by hydrothermal treatment of lime/silica fume mixtures with (Ca + Ba)/Si = 2 at 110°C for 5 hours. Hillebrandite partially dehydrates in two steps at 422 and 508°C and transforms to γ-C2S at 734°C which in turn transforms to α′-C2S at 955°C which in turn transforms to β-C2S when cooled. In presence of Ba2+ ions, β-C2S could be stabilized with minor transformation to γ-C2S. Mixture of silica fume, lime, and BaCl2 with the ratio of (Ca + Ba)/Si = 2 was successfully utilized for synthesis of β-C2S by hydrothermal treatment at 110°C for 5 hours followed by calcination of the product at 700°C for 3 hours. PMID:27437495

  19. Atomistic simulations of calcium uranyl(VI) carbonate adsorption on calcite and stepped-calcite surfaces.

    PubMed

    Doudou, Slimane; Vaughan, David J; Livens, Francis R; Burton, Neil A

    2012-07-17

    Adsorption of actinyl ions onto mineral surfaces is one of the main mechanisms that control the migration of these ions in environmental systems. Here, we present computational classical molecular dynamics (MD) simulations to investigate the behavior of U(VI) in contact with different calcite surfaces. The calcium-uranyl-carbonate [Ca(2)UO(2)(CO(3))(3)] species is shown to display both inner- and outer-sphere adsorption to the flat {101̅4} and the stepped {314̅8} and {31̅2̅16} planes of calcite. Free energy calculations, using the umbrella sampling method, are employed to simulate adsorption paths of the same uranyl species on the different calcite surfaces under aqueous condition. Outer-sphere adsorption is found to dominate over inner-sphere adsorption because of the high free energy barrier of removing a uranyl-carbonate interaction and replacing it with a new uranyl-surface interaction. An important binding mode is proposed involving a single vicinal water monolayer between the surface and the sorbed complex. From the free energy profiles of the different calcite surfaces, the uranyl complex was also found to adsorb preferentially on the acute-stepped {314̅8} face of calcite, in agreement with experiment.

  20. The surface interactions of a near-neutral carbon nanoparticle tracer with calcite

    NASA Astrophysics Data System (ADS)

    Li, Yan Vivian; Cathles, Lawrence M.

    2016-03-01

    A new class of nearly charge-neutral carbon-cored nanoparticle tracers are remarkably non-interactive with solid surfaces and could provide a valuable baseline for diverse hydrological and environmental studies of subsurface flow and particle transport. We investigate the causes of inertness by studying the interactions with calcite of a nanoparticle of this class synthesized from malic acid and ethanolamine (M-dots) dispersed in brine (NaCl, CaCl2, and MgCl2) solutions. None of the M-dots are retained in calcite sand-packed columns when dispersed in DI water. Dispersed in the NaCl and mixed brine solutions, 5.6 % of and 7.3 % of the M-dots are initially retained, but 65 and 13 % of these retained particles are subsequently released when the column is flushed with DI water. When dispersed in the CaCl2 and MgCl2 solutions, 65 and 54 % of the M-dots are initially retained, and 28 and 26 % subsequently released in the DI water flush. The M-dots have a small negative zeta potential in all solutions, but the calcite zeta potential changes from strongly negative to strongly positive across the solution series, and the particle retention tracks this change. Derjaguin-Landau-Verwey-Overbeek (DLVO) modeling of the force between a calcite probe and an M-dot coated surface shows that hydration forces repel the particles in the DI water, NaCl, and mixed solutions, but not in the CaCl2 and MgCl2 solutions. These results show that near-zero charge and strongly hydrophilic decoration are the causes of the remarkable inertness of carbon-cored nanoparticles, and also suggest that nanoparticles could be useful in solute-surface interaction studies.

  1. A mild alkali treated jute fibre controlling the hydration behaviour of greener cement paste.

    PubMed

    Jo, Byung-Wan; Chakraborty, Sumit

    2015-01-16

    To reduce the antagonistic effect of jute fibre on the setting and hydration of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and hydration behaviour of cement. Setting time measurement, hydration test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the hydration test, the time (t) required to reach maximum temperature for the hydration of control cement sample is estimated to be 860 min, whilst the time (t) is measured to be 1040 min for the hydration of a raw jute reinforced cement sample. However, the time (t) is estimated to be 1020 min for the hydration of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and hydration delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and hydration behaviour of alkali treated jute fibre reinforced cement composite.

  2. A mild alkali treated jute fibre controlling the hydration behaviour of greener cement paste

    NASA Astrophysics Data System (ADS)

    Jo, Byung-Wan; Chakraborty, Sumit

    2015-01-01

    To reduce the antagonistic effect of jute fibre on the setting and hydration of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and hydration behaviour of cement. Setting time measurement, hydration test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the hydration test, the time (t) required to reach maximum temperature for the hydration of control cement sample is estimated to be 860 min, whilst the time (t) is measured to be 1040 min for the hydration of a raw jute reinforced cement sample. However, the time (t) is estimated to be 1020 min for the hydration of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and hydration delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and hydration behaviour of alkali treated jute fibre reinforced cement composite.

  3. A mild alkali treated jute fibre controlling the hydration behaviour of greener cement paste

    PubMed Central

    Jo, Byung-Wan; Chakraborty, Sumit

    2015-01-01

    To reduce the antagonistic effect of jute fibre on the setting and hydration of jute reinforced cement, modified jute fibre reinforcement would be a unique approach. The present investigation deals with the effectiveness of mild alkali treated (0.5%) jute fibre on the setting and hydration behaviour of cement. Setting time measurement, hydration test and analytical characterizations of the hardened samples (viz., FTIR, XRD, DSC, TGA, and free lime estimation) were used to evaluate the effect of alkali treated jute fibre. From the hydration test, the time (t) required to reach maximum temperature for the hydration of control cement sample is estimated to be 860 min, whilst the time (t) is measured to be 1040 min for the hydration of a raw jute reinforced cement sample. However, the time (t) is estimated to be 1020 min for the hydration of an alkali treated jute reinforced cement sample. Additionally, from the analytical characterizations, it is determined that fibre-cement compatibility is increased and hydration delaying effect is minimized by using alkali treated jute fibre as fibre reinforcement. Based on the analyses, a model has been proposed to explain the setting and hydration behaviour of alkali treated jute fibre reinforced cement composite. PMID:25592665

  4. Effects of calcite and magnesite application to a declining Masson pine forest on strongly acidified soil in Southwestern China.

    PubMed

    Huang, Yongmei; Kang, Ronghua; Ma, Xiaoxiao; Qi, Yu; Mulder, Jan; Duan, Lei

    2014-05-15

    Liming of strongly acidified soil under a Masson pine (Pinus massoniana Lamb.) forest was studied through a seven-year field manipulation experiment at Tieshanping, Chongqing in Southwestern China. To distinguish between the individual effects of Ca(2+) and Mg(2+) addition, we separately applied calcite (CaCO3) and magnesite (MgCO3), rather than using dolomite [CaMg(CO3)2]. Both calcite and magnesite additions caused a significant increase in pH and a decrease in dissolved inorganic monomeric aluminium (Ali) concentration of soil water. Ecological recovery included increases of herb biomass (both treatments) and Mg content in Masson pine needles (magnesite treatment only). However, the growth rate of Masson pine did not increase under either treatment, possibly because of nutrient imbalance due to phosphorus (P) deficiency or limited observation period. In China, acid deposition in forest ecosystems commonly coincides with large inputs of atmogenic Ca(2+), both enhancing Mg(2+) leaching. Calcite addition may further decrease the Mg(2+) availability in soil water, thereby exacerbating Mg(2+) deficiency in the acidified forest soils of southern and southwestern China. The effect of anthropogenic acidification of naturally acid forest soils on P availability needs further study.

  5. 46 CFR 148.04-23 - Unslaked lime in bulk.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Unslaked lime in bulk. 148.04-23 Section 148.04-23... HAZARDOUS MATERIALS IN BULK Special Additional Requirements for Certain Material § 148.04-23 Unslaked lime in bulk. (a) Unslaked lime in bulk must be transported in unmanned, all steel, double-hulled...

  6. 27 CFR 9.27 - Lime Kiln Valley.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Lime Kiln Valley. 9.27... Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley.” (b) Approved Map. The appropriate map for determining the boundaries of the Lime Kiln...

  7. 27 CFR 9.27 - Lime Kiln Valley.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Lime Kiln Valley. 9.27... Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley.” (b) Approved Map. The appropriate map for determining the boundaries of the Lime Kiln...

  8. 27 CFR 9.27 - Lime Kiln Valley.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Lime Kiln Valley. 9.27... Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley.” (b) Approved Map. The appropriate map for determining the boundaries of the Lime Kiln...

  9. 27 CFR 9.27 - Lime Kiln Valley.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Lime Kiln Valley. 9.27... Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley.” (b) Approved Map. The appropriate map for determining the boundaries of the Lime Kiln...

  10. 27 CFR 9.27 - Lime Kiln Valley.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Lime Kiln Valley. 9.27... Kiln Valley. (a) Name. The name of the viticultural area described in this section is “Lime Kiln Valley.” (b) Approved Map. The appropriate map for determining the boundaries of the Lime Kiln...

  11. Origins of hydration lubrication.

    PubMed

    Ma, Liran; Gaisinskaya-Kipnis, Anastasia; Kampf, Nir; Klein, Jacob

    2015-01-14

    Why is friction in healthy hips and knees so low? Hydration lubrication, according to which hydration shells surrounding charges act as lubricating elements in boundary layers (including those coating cartilage in joints), has been invoked to account for the extremely low sliding friction between surfaces in aqueous media, but not well understood. Here we report the direct determination of energy dissipation within such sheared hydration shells. By trapping hydrated ions in a 0.4-1 nm gap between atomically smooth charged surfaces as they slide past each other, we are able to separate the dissipation modes of the friction and, in particular, identify the viscous losses in the subnanometre hydration shells. Our results shed light on the origins of hydration lubrication, with potential implications both for aqueous boundary lubricants and for biolubrication.

  12. Use of wastes of the sugar industry as pozzolana in lime-pozzolana binders: Study of the reaction

    SciTech Connect

    Hernandez, J.F.M.; Middendorf, B.; Gehrke, M.; Budelmann, H.

    1998-11-01

    Mineralogical studies of different wastes of the sugar industry, mainly sugar cane bagasse ash and sugar cane straw ash, have shown that such by-products are likely to be pozzolanic. Their use in lime-pozzolana binders could become an interesting alternative for developing countries. This paper presents a study that was aimed at monitoring the reaction between lime and wastes of the sugar industry having pozzolanic properties by evaluating (1) content of calcium hydroxide, dependent on time; (2) development of the pore structure, dependent on time; (3) study on the reaction products at different stages; and (4) mechanical properties of hardened pastes. The presence of calcium hydroxide was confirmed by x-ray diffraction analysis and thermogravimetric analysis of powder from samples of hydrated lime-pozzolana pastes. The reaction products in hydrated pastes were observed in a scanning electron microscope, and the pore structure was assessed using a mercury intrusion porosimeter. The results of the study show that sugar cane bagasse ash does not act like a reactive pozzolana, mainly due to the presence of unburned material and carbon, whereas sugar cane straw ash shows good pozzolanic activity comparable to that of rice husk ash.

  13. A new lime material for container substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The primary component in greenhouse potting substrates is sphagnum peatmoss. Substrate solution pH of non-amended peatmoss ranges from 4.0 to 4.5. Ideal pH for most greenhouse floriculture crops ranges from 5.8 to 6.2. Dolomitic lime is most often used to elevate substrate pH in peatmoss-based me...

  14. Oxidative lime pretreatment of Alamo switchgrass.

    PubMed

    Falls, Matthew; Holtzapple, Mark T

    2011-09-01

    Previous studies have shown that oxidative lime pretreatment is an effective delignification method that improves the enzymatic digestibility of many biomass feedstocks. The purpose of this work is to determine the recommended oxidative lime pretreatment conditions (reaction temperature, time, pressure, and lime loading) for Alamo switchgrass (Panicum virgatum). Enzymatic hydrolysis of glucan and xylan was used to determine the performance of the 52 studied pretreatment conditions. The recommended condition (110°C, 6.89 bar O(2), 240 min, 0.248 g Ca(OH)(2)/g biomass) achieved glucan and xylan overall yields (grams of sugar hydrolyzed/100 g sugar in raw biomass, 15 filter paper units (FPU)/g raw glucan) of 85.9 and 52.2, respectively. In addition, some glucan oligomers (2.6 g glucan recovered/100 g glucan in raw biomass) and significant levels of xylan oligomers (26.0 g xylan recovered/100 g xylan in raw biomass) were recovered from the pretreatment liquor. Combining a decrystallization technique (ball milling) with oxidative lime pretreatment further improved the overall glucan yield to 90.0 (7 FPU/g raw glucan).

  15. Fertilizer and Lime: Why They Are Used.

    ERIC Educational Resources Information Center

    McCaslin, Judith Strand

    This unit teaching guide is designed to help teachers explain the principles of fertilizer and lime use. The first of four major sections is a teaching outline keyed to transparency masters and student handouts. Thirteen major areas are covered in the teaching outline: (1) plant needs; (2) uses of fertilizer; (3) nutrients for plant growth; (4)…

  16. Removal of organic magnesium in coccolithophore calcite

    NASA Astrophysics Data System (ADS)

    Blanco-Ameijeiras, S.; Lebrato, M.; Stoll, H. M.; Iglesias-Rodriguez, M. D.; Méndez-Vicente, A.; Sett, S.; Müller, M. N.; Oschlies, A.; Schulz, K. G.

    2012-07-01

    Coccolithophore calcite refers to the plates of calcium carbonate (CaCO3) produced by the calcifying phytoplankton, coccolithophores. The empirical study of the elemental composition has a great potential in the development of paleoproxies. However, the difficulties to separate coccolithophore carbonates from organic phases hamper the investigation of coccoliths magnesium to calcium ratios (Mg/Ca) in biogeochemical studies. Magnesium (Mg) is found in organic molecules in the cells at concentrations up to 400 times higher than in inorganically precipitated calcite in present-day seawater. The aim of this study was to optimize a reliable procedure for organic Mg removal from coccolithophore samples to ensure reproducibility in measurements of inorganic Mg in calcite. Two baseline methods comprising organic matter oxidations with (1) bleach and (2) hydrogen peroxide (H2O2) were tested on synthetic pellets, prepared by mixing reagent grade CaCO3 with organic matter from the non-calcifying marine algae Chlorella autotrophica and measured with an ICP-AES (inductively coupled plasma-atomic emission spectrometer). Our results show that treatments with a reductive solution [using hydroxylamine-hydrochloride (NH2OH·HCl + NH4OH)] followed by three consecutive oxidations (using H2O2) yielded the best cleaning efficiencies, removing >99% of organic Mg in 24 h. P/Ca and Fe/Ca were used as indicators for organic contamination in the treated material. The optimized protocol was tested in dried coccolithophore pellets from batch cultures of Emiliania huxleyi, Calcidiscus leptoporus and Gephyrocapsa oceanica. Mg/Ca of treated coccolithophores were 0.151 ± 0.018, 0.220 ± 0.040, and 0.064 ± 0.023 mmol/mol, respectively. Comparison with Mg/Ca literature coccolith values, suggests a tight dependence on modern seawater Mg/Ca, which changes as a consequence of different seawater origins (<10%). The reliable determination of Mg/Ca and Sr/Ca, and the low levels of organic contamination

  17. LIME mediates immunological synapse formation through activation of VAV.

    PubMed

    Son, Myoungsun; Park, Inyoung; Lee, Ok-Hee; Rhee, Inmoo; Park, Changwon; Yun, Yungdae

    2012-04-01

    Lck Interacting Membrane protein (LIME) was previously characterized as a transmembrane adaptor protein mediating TCR-dependent T cell activation. Here, we show that LIME associates with Vav in response to TCR stimulation and is required for Vav guanine nucleotide exchange factor (GEF) activity for Rac1. Consistent with this finding, actin polymerization at the immunological synapse (IS) was markedly enhanced by overexpression of LIME, but was reduced by expression of a LIME shRNA. Moreover, TCR-mediated cell adhesion to ICAM-1, laminin, or fibronectin was downregulated by expression of LIME shRNA. In addition, in the IS, LIME but not LAT was found to localize at the peripheral-supramolecular activation cluster (p-SMAC) where the integrins were previously shown to be localized. Together, these results establish LIME as a transmembrane adaptor protein linking TCR stimulation to IS formation and integrin activation through activation of Vav.

  18. The origin of carbon isotope vital effects in coccolith calcite

    PubMed Central

    McClelland, H. L. O.; Bruggeman, J.; Hermoso, M.; Rickaby, R. E. M.

    2017-01-01

    Calcite microfossils are widely used to study climate and oceanography in Earth's geological past. Coccoliths, readily preserved calcite plates produced by a group of single-celled surface-ocean dwelling algae called coccolithophores, have formed a significant fraction of marine sediments since the Late Triassic. However, unlike the shells of foraminifera, their zooplankton counterparts, coccoliths remain underused in palaeo-reconstructions. Precipitated in an intracellular chemical and isotopic microenvironment, coccolith calcite exhibits large and enigmatic departures from the isotopic composition of abiogenic calcite, known as vital effects. Here we show that the calcification to carbon fixation ratio determines whether coccolith calcite is isotopically heavier or lighter than abiogenic calcite, and that the size of the deviation is determined by the degree of carbon utilization. We discuss the theoretical potential for, and current limitations of, coccolith-based CO2 paleobarometry, that may eventually facilitate use of the ubiquitous and geologically extensive sedimentary archive. PMID:28262764

  19. The origin of carbon isotope vital effects in coccolith calcite

    NASA Astrophysics Data System (ADS)

    McClelland, H. L. O.; Bruggeman, J.; Hermoso, M.; Rickaby, R. E. M.

    2017-03-01

    Calcite microfossils are widely used to study climate and oceanography in Earth's geological past. Coccoliths, readily preserved calcite plates produced by a group of single-celled surface-ocean dwelling algae called coccolithophores, have formed a significant fraction of marine sediments since the Late Triassic. However, unlike the shells of foraminifera, their zooplankton counterparts, coccoliths remain underused in palaeo-reconstructions. Precipitated in an intracellular chemical and isotopic microenvironment, coccolith calcite exhibits large and enigmatic departures from the isotopic composition of abiogenic calcite, known as vital effects. Here we show that the calcification to carbon fixation ratio determines whether coccolith calcite is isotopically heavier or lighter than abiogenic calcite, and that the size of the deviation is determined by the degree of carbon utilization. We discuss the theoretical potential for, and current limitations of, coccolith-based CO2 paleobarometry, that may eventually facilitate use of the ubiquitous and geologically extensive sedimentary archive.

  20. Cloud Condensation Nucleus Activity of calcite and calcite coated with model humic and fulvic acids

    NASA Astrophysics Data System (ADS)

    Hatch, C. D.; Gierlus, K. M.; Schuttlefield, J. D.; Grassian, V. H.

    2007-12-01

    Many recent studies have shown that organics can alter the water adsorption and cloud condensation nuclei (CCN) activity of common deliquescent species in the Earth's atmosphere. However, very little is known about the effect of organics on water adsorption and CCN activity of common inactive cloud nuclei, such as mineral aerosol. As many studies have shown that a large fraction of unidentified organic material in aerosol particles is composed of polycarboxylic acids resembling humic substances, the presence of these large molecular weight Humic-Like Substances (HULIS) may also alter the water adsorption and CCN activity of mineral aerosol. Thus, we have measured the water adsorption and CCN activity of model humic and fulvic acids. Additionally, the water adsorption and CCN activity of mineral aerosol particles coated with humic and fulvic acids have been studied. We find that humic and fulvic acids show continual multilayer water adsorption as the relative humidity is raised. Additionally, we find that calcite particles mixed with humic and fulvic acids take up more water by mass, by a factor of two, compared to the uncoated calcite particles at approximately 70% RH. CCN measurements also indicate that internally mixed calcite-humic or fulvic acid aerosols are more CCN active than the otherwise inactive, uncoated calcite particles. Our results suggest that mineral aerosol particles coated with high molecular weight organic materials will take up more water and become more efficient CCN in the Earth's atmosphere than single-component mineral aerosol.

  1. Fibrous calcite from the Middle Ordovician Holston Formation (east Tennessee)

    SciTech Connect

    Tobin, K.J.; Walker, K.R. . Dept. of Geological Sciences)

    1993-03-01

    Fibrous calcite from buildups, which occur near the top of the Middle Ordovician Holston Formation, were examined from two localities near Knoxville, TN (Alcoa Highway and Deanne Quarry). Buildups at these localities were deposited under open-marine conditions, slightly down-slope from the platform edge. Fibrous calcite (mainly radiaxial fibrous) occur most commonly as cements in mainly stromatactis structures present in bioherms and intergranular porosity in beds that flank bioherms. Fibrous calcite is interpreted to have been precipitated in a marine setting. Fibrous calcite is uniformly turbid or banded with interlayered turbid and clearer cement. Fibrous calcite most commonly shows patchy or blotchy dull-non-luminescence under cathodoluminescence. Bands of uniformly non-luminescent and relatively bright luminescent calcite are present. [delta][sup 13]C compositions of fibrous calcite vary little (0.6 to 1.0%) but [delta][sup 18]O values are highly variable ([minus]4.8 to [minus]7.1%). Post-marine cement consists of ferroan and non-ferroan, dull luminescent equant calcite ([delta][sup 13]C = 0.3 to 0.8; [delta][sup 18]O = [minus]8.6 to [minus]11.5) and is interpreted as precipitated in a deep meteoric or burial setting. Depleted [delta][sup 18]O compositions of fibrous calcite reflect addition of post-depositional calcite during stabilization. Most enriched [delta][sup 13]C and [delta][sup 18]O fibrous calcite composition are similar to enriched values from other Middle Ordovician southern Appalachian buildups (other localities of Holston (TN) and Effna (VA) formations) ([delta][sup 13]C = 0.3 to 0.8; [delta][sup 18]O = [minus]3.9 to [minus]4.8) and may reflect fibrous calcite precipitated in isotopic equilibrium with Middle Ordovician sea water.

  2. An improved clearing and mounting solution to replace chloral hydrate in microscopic applications1

    PubMed Central

    Villani, Thomas S.; Koroch, Adolfina R.; Simon, James E.

    2013-01-01

    • Premise of the study: This study presents Visikol™, a new proprietary formulation that can be used as an efficient replacement for chloral hydrate as a clearing agent for microscopic examination. In the United States, chloral hydrate is regulated and therefore difficult to acquire. • Methods and Results: Fresh and dry samples of the following plants: ginger (Zingiber officinale), maté (Ilex paraguariensis), lime basil (Ocimum americanum), oregano (Origanum vulgare), and mouse-ear cress (Arabidopsis thaliana), were cleared using Visikol or chloral hydrate solution and compared using a light microscope. • Conclusions: This new method can be used successfully to clear specimens, allowing identification of diagnostic characteristics for the identification of plant materials. Visikol is as effective as chloral hydrate in providing clarity and resolution of all tissues examined. Tissues become transparent, allowing observation of deeper layers of cells and making it effective in research, botanical and quality control, and for educational applications. PMID:25202549

  3. Roller compacted base course construction using lime stabilized fly ash and flue gas desulfurization sludge by-product

    SciTech Connect

    Beeghly, J.J.

    1996-10-01

    Dewatered calcium sulfite and calcium sulfate sludges from flue gas desulfurization (FGD) processes at coal fired power plants can be mixed with coal fly ash and lime to cause a cementitious chemical reaction used to construct a roller compacted base course or an impermeable pond liner. Tile chemical reaction is often shown as lime reacting with alumina from the fly ash which in turn reacts with the calcium sulfite and sulfate FGD waste to form sulfo-aluminate. Better understanding is needed of the controlling factors that result in a successful application of this chemical reaction which has been linked to past construction failures due to latent hydration causing expansion damage or degradation of concrete, called sulfate attack. Factors such as optimum moisture content, fly ash to FGD ratio, and age of FGD are examined that affect strength gain and freeze-thaw durability. Several recently completed field demonstrations are discussed.

  4. Spectroscopic characterization of natural calcite minerals

    NASA Astrophysics Data System (ADS)

    Gunasekaran, S.; Anbalagan, G.

    2007-11-01

    The FT-IR, FT-Raman, NMR spectral data of ten different limestone samples have been compared. FT-IR and FT-Raman spectral data show that calcium carbonate in limestone, principally in the form of calcite, as identified by its main absorption bands at 1426, 1092, 876 and 712 cm -1. The sharp diffractions at the d-spacings, 3.0348, 1.9166 and 1.8796 confirm the presence of calcite structure and the calculated lattice parameters are: a = 4.9781 Å, c = 17.1188 Å. The range of 13C chemical shifts for different limestone samples is very small, varying from 198.38 to 198.42 ppm. The observed chemical shifts are consistent with the identical C-O bonding in different limestone samples. 27Al MAS NMR spectra of the samples exhibit a central line at 1 ppm and another line at 60 ppm corresponding to octahedral and tetrahedral Al ions, respectively. The five component resonances were observed in 29Si MAS NMR spectrum of limestone and these resonances were assigned to Si (4 Al), Si (3 Al), Si (2 Al), Si (1 Al) and Si (0 Al) from low field to high field.

  5. Fly ash as a liming material for corn production

    SciTech Connect

    Tarkalson, D.D.; Hergert, G.W.; Stevens, W.B.; McCallister, D.L.; Kackman, S.D.

    2005-05-01

    Fly ash produced as a by-product of subbituminous coal combustion can potentially serve as an alternative liming material without negatively affecting corn (Zea mays L.) production in areas where use of conventional liming materials can be uneconomical due to transportation costs. A study was conducted to determine if fly ash produced from the Nebraska Public Power District Gerald Gentleman Power Station located in Sutherland, NE could be used as an alternative liming material. Combinations of dry fly ash (DFA), wet fly ash (WFA), beet lime (by-product of sugar beet (Beta vulgaris L.) processing) (BL), and agricultural lime (AGL) were applied at rates ranging from 0.43 to 1.62 times the recommended lime rate to plots on four acidic soils (Anselmo fine sandy loam, Hord fine sandy loam, Holdrege sandy loam, and Valentine fine sand). Soil samples were collected to a depth of 0.2 m from plots and analyzed for pH before lime applications and twice periodically after lime application. The Hord and Valentine soils were analyzed for exchangeable Ca, Mg, K, Na,and Al for determination of percent Al saturation on selected treatments and sampling dates. Corn grain yields were determined annually. It is concluded that the fly ash utilized in this study and applied at rates in this study, increases soil pH comparable to agricultural lime and is an appropriate alternative liming material.

  6. Hydration rate of obsidian.

    PubMed

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years.

  7. Friction characteristics of Cd-rich carbonate films on calcite surfaces: implications for compositional differentiation at the nanometer scale

    PubMed Central

    2009-01-01

    Lateral Force Microscopy (LFM) studies were carried out on cleaved calcite sections in contact with solutions supersaturated with respect to otavite (CdCO3) or calcite-otavite solid solutions (SS) as a means to examine the potential for future application of LFM as a nanometer-scale mineral surface composition mapping technique. Layer-by-layer growth of surface films took place either by step advancement or by a surface nucleation and step advancement mechanisms. Friction vs. applied load data acquired on the films and the calcite substrate were successfully fitted to the Johnson Kendall Roberts (JKR) model for single asperity contacts. Following this model, friction differences between film and substrate at low loads were dictated by differences in adhesion, whereas at higher load they reflect differences in contact shear strength. In most experiments at fixed load, the film showed higher friction than the calcite surface, but the friction-load dependence for the different surfaces revealed that at low loads (0–40 nN), a calcian otavite film has lower friction than calcite; a result that is contrary to earlier LFM reports of the same system. Multilayer films of calcian-otavite displayed increasing friction with film thickness, consistent with the expectation that the film surface composition will become increasingly Cd-rich with increasing thickness. Both load- and thickness-dependence trends support the hypothesis that the contact shear strength correlates with the hydration enthalpy of the surface ions, thereby imparting friction sensitivity in the LFM to mineral-water interface composition. PMID:19549312

  8. An Aerobic Digestion of Lime Sludge.

    DTIC Science & Technology

    1982-07-01

    defined for process control. LITERATURE REVIEW GENERAL CONDITIONS The process of anaerobic digestion may be considered to occur in three stages . The... anaerobic digestion process can result in significantly higher digester volume require- ments. The characteristics of lime sludge degradatioA were...considerations: 1. The stabilized sludge must be of acceptable quality for disposal for the anaerobic digestion process to be feasible. 2. Since

  9. Neptunium(V) adsorption to calcite.

    PubMed

    Heberling, Frank; Brendebach, Boris; Bosbach, Dirk

    2008-12-12

    The migration behavior of the actinyl ions U(VI)O2(2+), Np(V)O2+ and Pu(V,VI)O2(+,2+) in the geosphere is to a large extend controlled by sorption reactions (inner- or outer-sphere adsorption, ion-exchange, coprecipitation/structural incorporation) with minerals. Here NpO2+ adsorption onto calcite is studied in batch type experiments over a wide range of pH (6.0-9.4) and concentration (0.4 microM-40 microM) conditions. pH is adjusted by variation of CO2 partial pressure. Adsorption is found to be pH dependent with maximal adsorption at pH 8.3 decreasing with increasing and decreasing pH. pH dependence of adsorption decreases with increasing Np(V) concentration. EXAFS data of neptunyl adsorbed to calcite and neptunyl in the supernatant shows differences in the Np(V)-O-yl distance, 1.85+/-0.01 angstroms for the adsorbed and 1.82+/-0.01 angstroms for the solution species. The equatorial environment of the neptunyl in solution shows about 5 oxygen neighbours at 2.45+/-0.02 angstroms. For adsorbed neptunyl there are also about 5 oxygen neighbours at 2.46+/-0.01 angstroms. An additional feature in the adsorbed species' R-space spectrum can be related to carbonate neighbours, 3 to 6 carbon backscatterers (C-eq) at 3.05+/-0.03 angstroms and 3 to 6 oxygen backscatterers (O-eq2) at 3.31+/-0.02 angstroms. The differences in the Np(V)-O-yl distance and the C-eq and O-eq2 backscatterers which are only present for the adsorbed species indicate inner-sphere bonding of the adsorbed neptunyl species to the calcite surface. Experiments on adsorption kinetics indicate that after a fast surface adsorption process a continuous slow uptake occurs which may be explained by incorporation via surface dissolution and reprecipitation processes. This is also indicated by the part irreversibility of the adsorption as shown by increased KD values after desorption compared to adsorption.

  10. Combustion of Methane Hydrate

    NASA Astrophysics Data System (ADS)

    Roshandell, Melika

    A significant methane storehouse is in the form of methane hydrates on the sea floor and in the arctic permafrost. Methane hydrates are ice-like structures composed of water cages housing a guest methane molecule. This caged methane represents a resource of energy and a potential source of strong greenhouse gas. Most research related to methane hydrates has been focused on their formation and dissociation because they can form solid plugs that complicate transport of oil and gas in pipelines. This dissertation explores the direct burning of these methane hydrates where heat from the combustion process dissociates the hydrate into water and methane, and the released methane fuels the methane/air diffusion flame heat source. In contrast to the pipeline applications, very little research has been done on the combustion and burning characteristics of methane hydrates. This is the first dissertation on this subject. In this study, energy release and combustion characteristics of methane hydrates were investigated both theoretically and experimentally. The experimental study involved collaboration with another research group, particularly in the creation of methane hydrate samples. The experiments were difficult because hydrates form at high pressure within a narrow temperature range. The process can be slow and the resulting hydrate can have somewhat variable properties (e.g., extent of clathration, shape, compactness). The experimental study examined broad characteristics of hydrate combustion, including flame appearance, burning time, conditions leading to flame extinguishment, the amount of hydrate water melted versus evaporated, and flame temperature. These properties were observed for samples of different physical size. Hydrate formation is a very slow process with pure water and methane. The addition of small amounts of surfactant increased substantially the hydrate formation rate. The effects of surfactant on burning characteristics were also studied. One finding

  11. Methane Hydrates: Chapter 8

    USGS Publications Warehouse

    Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

    2008-01-01

    Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

  12. Effect of Microorganism Sporosarcina pasteurii on the Hydration of Cement Paste.

    PubMed

    Lee, Jun Cheol; Lee, Chang Joon; Chun, Woo Young; Kim, Wha Jung; Chung, Chul-Woo

    2015-08-01

    Years of research have shown that the application of microorganisms increases the compressive strength of cement-based material when it is cured in a culture medium. Because the compressive strength is strongly affected by the hydration of cement paste, this research aimed to investigate the role of the microorganism Sporosarcina pasteurii in hydration of cement paste. The microorganism's role was investigated with and without the presence of a urea-CaCl2 culture medium (i.e., without curing the specimens in the culture medium). The results showed that S. pasteurii accelerated the early hydration of cement paste. The addition of the urea-CaCl2 culture medium also increased the speed of hydration. However, no clear evidence of microbially induced calcite precipitation appeared when the microorganisms were directly mixed with cement paste.

  13. Urease activity in microbiologically-induced calcite precipitation.

    PubMed

    Bachmeier, Keri L; Williams, Amy E; Warmington, John R; Bang, Sookie S

    2002-02-14

    The role of microbial urease in calcite precipitation was studied utilizing a recombinant Escherichia coli HB101 containing a plasmid, pBU11, that encodes Bacillus pasteurii urease. The calcite precipitation by E. coli HB101 (pBU11) was significant although its precipitation level was not as high as that by B. pasteurii. Addition of low concentrations (5-100 microM) of nickel, the cofactor of urease, to the medium further enhanced calcite precipitation by E. coli (pBU11). Calcite precipitation induced by both B. pasteurii and E. coli (pBU11) was inhibited in the presence of a urease inhibitor, acetohydroxamic acid (AHA). These observations on the recombinant urease have confirmed that urease activity is essential for microbiologically-induced calcite precipitation. Partially purified B. pasteurii urease was immobilized in polyurethane (PU) foam to compare the efficacy of calcite precipitation between the free and immobilized enzymes. The immobilized urease showed higher K(m) and lower V(max) values, which were reflected by a slower overall calcite precipitation. However, scanning electron micrographs (SEM) identified that the calcite precipitation occurred throughout the matrices of polyurethane. Furthermore, PU-immobilized urease retained higher enzymatic activities at high temperatures and in the presence of a high concentration of pronase, indicating that immobilization protects the enzyme activity from environmental changes.

  14. Emission polarization study on quartz and calcite.

    NASA Technical Reports Server (NTRS)

    Vincent, R. K.

    1972-01-01

    Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

  15. Comparison of garnet-biotite, calcite-graphite, and calcite-dolomite thermometry in the Grenville Orogen; Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Rathmell, Mark A.; Streepey, Margaret M.; Essene, Eric J.; van der Pluijm, Ben A.

    The Elzevir Terrane of the Grenville Orogen in southern Ontario contains metapelites and abundant graphitic marbles that were regionally metamorphosed from the upper greenschist to upper amphibolite facies. Comparative thermometry was undertaken with widely used calibrations for the systems garnet-biotite, calcite-dolomite, and calcite-graphite. Temperatures that are obtained from matrix biotites paired with prograde garnet near-rim analyses are usually consistent with those determined using calcite-graphite thermometry. However, calcite-graphite thermometry occasionally yields low temperatures due to lack of equilibration of anomalously light graphite. Application of calcite-graphite and garnet-biotite systems may yield temperatures up to 70°C higher than calcite-dolomite in amphibolite facies rocks. Calcite-dolomite temperatures most closely approach those from calcite-graphite and garnet-biotite when the samples contain a single generation of dolomite and calcite grains contain no visible dolomite exsolution lamellae. However, some of these samples yield temperatures considerably lower than temperatures calculated from calcite-graphite and garnet-biotite thermometry, indicating that the calcite-dolomite thermometer may have been partially reset during retrogression. Estimated peak metamorphic temperatures of regional metamorphism between Madoc (upper greenschist facies) and Bancroft (upper amphibolite facies) range from 500 to 650°C. These results place the chlorite-staurolite isograd at 540°C, the kyanite-sillimanite isograd at 590°C, and the sillimanite-K-feldspar isograd at 650°C. Although each thermometer may have an absolute uncertainty of as much as +/-50°C, the 50 to 60°C temperature differences between the isograds are probably accurate to 10 to 20°C. An incomplete picture of the thermal gradients can result from the application of only one thermometer in a given area. Simultaneous application of several systems allows one to recognize and

  16. Rate limitations of lime dissolution into coal ash slag

    SciTech Connect

    L.K. Elliott; John A. Lucas; Jim Happ; John Patterson; Harry Hurst; Terry F. Wall

    2008-11-15

    The rate-limiting mechanisms of lime dissolution from a solid pellet into coal ash slag and synthetic slag was investigated using an experiment involving a rotating cylinder of lime in a liquid slag bath at temperatures of 1450-1650{degree}C. Scanning electron microscopy (SEM) analysis of the slag composition around the lime cylinder was used to determine the nature of the boundary layer surrounding the pellet and the calcium concentration profile. Predictions using shrinking core models of a cylindrical pellet were compared to experimental results, suggesting that diffusion through the slag boundary layer and the change of the phase of lime from solid to liquid in the boundary layer combine to limit the process. These results indicate that a combination of controlling steps: diffusion through the boundary layer and the phase change of lime from solid to liquid, must be considered when predicting lime dissolution rates. 24 refs., 5 figs., 3 tabs.

  17. Transformations in methane hydrates

    USGS Publications Warehouse

    Chou, I.-Ming; Sharma, A.; Burruss, R.C.; Shu, J.; Mao, Ho-kwang; Hemley, R.J.; Goncharov, A.F.; Stern, L.A.; Kirby, S.H.

    2000-01-01

    Detailed study of pure methane hydrate in a diamond cell with in situ optical, Raman, and x-ray microprobe techniques reveals two previously unknown structures, structure II and structure H, at high pressures. The structure II methane hydrate at 250 MPa has a cubic unit cell of a = 17.158(2) A?? and volume V = 5051.3(13) A??3; structure H at 600 MPa has a hexagonal unit cell of a = 11.980(2) A??, c = 9.992(3) A??, and V = 1241.9(5) A??3. The compositions of these two investigated phases are still not known. With the effects of pressure and the presence of other gases in the structure, the structure II phase is likely to dominate over the known structure I methane hydrate within deep hydrate-bearing sediments underlying continental margins.

  18. Liming of acidified waters: issues and research - a report of the International Liming Workshop

    USGS Publications Warehouse

    Schreiber, R. Kent

    1982-01-01

    Acidic deposition is a problem of significant national and international concern. It is strongly suspected that acidic deposition has adversely affected aquatic resources in Scandinavia and North America. While substantial resources are being devoted to understanding the causative factors associated with surface water acidification, much less research is being conducted on mitigative strategies. Mitigative techniques involving liming may be useful for short-term protection of specific component of aquatic communities or for renovation of seriously impacted aquatic ecosystems. The selection of effective liming strategies is based on an integrated understanding of the following key factors: biological systems, water chemistry, sediment chemistry, hydrology, and watershed characteristics, effectiveness of neutralizing materials, and application techniques. Research in Scandinavia, Canada, and the U.S. has led to a partial understanding of some of the key factors for successful neutralization of surface waters (Bengtsson, 1982; Fraser and Britt, 1982). However, conflicting results of liming operations and experiments have been reported. (Fraser et al., 1982; Fraser and Britt, 1982; Sverdrup and Bjerle, 1982). Additional research is required to improve the ability of scientists and resource managers to select effective liming strategies. An International Liming workshop was convened during 19-25 September 1982 at the University of Washington's Friday Harbor Laboratories. The major objective of this workshop were: - To identify the most critical deficiencies in the scientific understanding of liming techniques and their long-term consequences. - To develop and document a research strategy to address information deficiencies that are pertinent to the protection or renovation of acidic surface waters in the United States. The participants who contributed to this workshop are listed in Table 1.

  19. Hydrate morphology: Physical properties of sands with patchy hydrate saturation

    USGS Publications Warehouse

    Dai, S.; Santamarina, J.C.; Waite, William F.; Kneafsey, T.J.

    2012-01-01

    The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

  20. Differences in the immobilization of arsenite and arsenate by calcite

    NASA Astrophysics Data System (ADS)

    Yokoyama, Yuka; Tanaka, Kazuya; Takahashi, Yoshio

    2012-08-01

    The sorption and coprecipitation experiments of arsenic (As) with calcite coupled with determinations of the chemical state of As both in the reaction fluid and in calcite were conducted to investigate the influence of the As oxidation state on its immobilization into calcite. The oxidation states of As in calcite and water were determined via As K-edge XANES and HPLC-ICP-MS analysis, respectively. The results of the sorption experiments at pH 8.2 show that only As(V) is distributed to calcite regardless of the As oxidation state in the solution. In coprecipitation experiments, As(V) is preferentially incorporated into calcite over a wide range of pH (7-12). On the other hand, the incorporation of As(III) into calcite is not observed at circumneutral pH. This difference between As(III) and As(V) is attributed to the fact that their dissolved species are neutral vs. negatively charged, respectively, at circumneutral pH (arsenite as H3AsO3; arsenate as H2AsO4- or HAsO42-). As the pH increases (>9), up to 33% of As(III)/Astotal ratio is partitioned into calcite or a precursor of calcite (metastable vaterite formed during the early stage of precipitation). The higher interaction of As with calcite at an alkaline pH compared with circumneutral pH is due to the negative charge of As(III) at alkaline pH. However, the As(III)/Astotal ratio decreases as time progresses and only As(V) can be found finally in calcite. The ratio of distribution coefficients of As(III) and As(V) into calcite (KAs(V)/KAs(III)) at pH ˜7 is larger than 2.1 × 103, suggesting that the oxidation state of As is a significant issue in considering the interaction between As and calcite in groundwater. Moreover, low KAs(III) shows that the sequestration of As via coprecipitation with calcite is not an important chemical process under reducing conditions, such as in the groundwaters in Bangladesh and other As-contaminated areas where As(III) is the dominant dissolved species of As. In the system spiked

  1. Strontium Incorporation into Calcite Generated by Bacterial Ureolysis

    SciTech Connect

    Yoshiko Fujita; George D. Redden; Jani C. Ingram; Marnie M. Cortez; Robert W. Smith

    2004-08-01

    Strontium incorporation into calcite generated by bacterial ureolysis was investigated as part of an assessment of a proposed remediation approach for 90Sr contamination in groundwater. Urea hydrolysis produces ammonium and carbonate and elevates pH, resulting in the promotion of calcium carbonate precipitation. Urea hydrolysis by the bacterium Bacillus pasteurii in a medium designed to mimic the chemistry of the Snake River Plain Aquifer in Idaho resulted in a pH rise from 7.5 to 9.1. Measured average distribution coefficients (DEX) for Sr in the calcite produced by ureolysis (0.5) were up to an order of magnitude higher than values reported in the literature for natural and synthetic calcites (0.02–0.4). They were also higher than values for calcite produced abiotically by ammonium carbonate addition (0.3). The precipitation of calcite in these experiments was verified by X-ray diffraction. Time-of-flight secondary ion mass spectrometry (ToF SIMS) depth profiling (up to 350 nm) suggested that the Sr was not merely sorbed on the surface, but was present at depth within the particles. X-ray absorption near edge spectra showed that Sr was present in the calcite samples as a solid solution. The extent of Sr incorporation appeared to be driven primarily by the overall rate of calcite precipitation, where faster precipitation was associated with greater Sr uptake into the solid. The presence of bacterial surfaces as potential nucleation sites in the ammonium carbonate precipitation treatment did not enhance overall precipitation or the Sr distribution coefficient. Because bacterial ureolysis can generate high rates of calcite precipitation, the application of this approach is promising for remediation of 90Sr contamination in environments where calcite is stable over the long term.

  2. Production Engineering for Growth of Synthetic Calcite Polarizer Material

    DTIC Science & Technology

    1974-08-01

    AD-A008 043 PRODUCTION ENGINEERING FOR GROWTH OF SYNTHETIC CALCITE POLARIZER MATERIAL Roger F. Belt, et al Litton Systems...Production Bngin««ring for Growth of Synthetic Calcit « Polarizer Material I. RCCIPItNT’tCATALOO NUMMN i. T.vpc or ncpoMT • rtmoo covtnto Final Report...VOKOt (CanlliMit en »xift •id« II ntffrt Kid Idtnlllr br block iwmbmr) Crystal Growth Hydrothermal Growth Calcite Polarizers 30. AtSTHACT

  3. Uptake of chloride and carbonate ions by calcium monosulfoaluminate hydrate

    SciTech Connect

    Mesbah, Adel; Cau-dit-Coumes, Celine; Frizon, Fabien

    2012-08-15

    Decommissioning of old nuclear reactors may produce waste streams containing chlorides and carbonates, including radioactive {sup 36}Cl{sup -} and {sup 14}CO{sub 3}{sup 2-}. Their insolubilization by calcium monosulfoaluminate hydrate was investigated. Carbonates were readily depleted from the solution, giving at thermodynamic equilibrium monocarboaluminate, monocarboaluminate + calcite, or calcite only, depending on the initial ratio between the anion and calcium monosulfoaluminate hydrate. Chloride ions reacted more slowly and were precipitated as Kuzel's salt, Kuzel's and Friedel's salts, or Friedel's salt only. Rietveld refinement of X-Ray powder diffraction patterns was successfully used to quantify the phase distributions, which were compared to thermodynamic calculations. Moreover, analysing the lattice parameters of Kuzel's salt as a function of its chloride content showed the occurrence of a restricted solid solution towards the sulfate side with general formula 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}xCaCl{sub 2}{center_dot}(1 - x)CaSO{sub 4}{center_dot}(12 - 2x){center_dot}H{sub 2}O (0.36 {<=} x {<=} 0.50).

  4. 77 FR 45715 - Application of Key Lime Air Corporation for Commuter Authority

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-01

    ...] Application of Key Lime Air Corporation for Commuter Authority AGENCY: Department of Transportation. ACTION... Lime Air Corporation fit, willing, and able, and awarding it a Commuter Air Carrier...

  5. Magnesium inhibition of calcite dissolution kinetics

    SciTech Connect

    Arvidson, Rolf S.; Collier, Martin; Davis, Kevin J.; Vinson, Michael D.; Amonette, James E.; Luttge, Andreas

    2006-02-01

    We present evidence of inhibition of calcite dissolution by dissolved magnesium through direct observations of the (104) surface using atomic force microscopy (AFM) and vertical scanning interferometry (VSI). Far from equilibrium, the pattern of magnesium inhibition is dependent on solution composition and specific to surface step geometry. In CO2-free solutions (pH 8.8), dissolved magnesium brings about little inhibition even at concentrations of 0.8 x 10-3 molal. At the same pH, magnesium concentrations of less than 0.05 x 10-3 molal in carbonate-buffered solutions generate significant inhibition, although no changes in surface and etch pit morphology are observed. As concentrations exceed magnesite saturation, the dissolution rate shows little additional decrease; however, selective pinning of step edges results in unique etch-pit profiles, seen in both AFM and VSI datasets. Despite the decreases in step velocity, magnesium addition in carbonated solutions also appears to activate the surface by increasing the nucleation rate of new defects. These relationships suggest that the modest depression of the bulk rate measured by VSI reflects a balance between competing reaction mechanisms that simultaneously depress the rate through selective inhibition of step movement, but also enhance reactivity on terraces by lowering the energy barrier to new etch-pit formation.

  6. Sliding behavior of calcite and dolomite marbles at seismic deformation conditions

    NASA Astrophysics Data System (ADS)

    Spagnuolo, E.; Smith, S. A.; Niemeijer, A. R.; di Toro, G.; Nielsen, S.

    2010-12-01

    for dolomite. In calcite, the decrease in friction follows an exponential decay, whereas in dolomite the friction drop is complicated by a short-duration phase of re-strengthening. Preliminary investigations on calcite marble indicate that axial shortening measured during the experiments is inversely correlated to slip rate. At low slip rates (<0.2 m/s), samples shorten significantly due to bulk fracturing and loss of gouge material from the sliding surface. However, at high slip rates (>0.5 m/s) shortening is negligible and loss of gouge material is generally not observed. Microstructural analyses suggest that negligible shortening may be related to the formation of ‘protective’ layers of CaO (lime) along the slip surface during fast slip, resulting in low wear rates and extremely thin (compared to silicate-bearing rocks deformed under similar conditions) slipping zones. The observation of decomposition layers in the post-experimental slipping zone seems to support this, although more elaborate analyses are currently in progress.

  7. 76 FR 82295 - Central Power & Lime LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Central Power & Lime LLC; Notice of Filing December 23, 2011. Take notice that on December 22, 2011, Central Power & Lime LLC, pursuant to sections 18 CFR 292.205(c) and...

  8. Mitigation of acid deposition: Liming of surface waters. Final report

    SciTech Connect

    Bartoshesky, J.; Price, R.; DeMuro, J.

    1989-05-01

    In recent years acid deposition has become a serious concern internationally. Scientific literature has documented the acidification of numerous lakes and streams in North America and Scandinavia resulting in the depletion or total loss of fisheries and other aquatic biota. Liming represents the only common corrective practice aimed specifically at remediating an affected acid receptor. This report reviews a range of liming technologies and liming materials, as well as the effect of surface-water liming on water quality and aquatic biota. As background to the liming discussion, the hydrologic cycle and the factors that make surface waters sensitive to acid deposition are also discussed. Finally, a brief review of some of the liming projects that have been conducted, or are currently in operation is presented, giving special emphasis to mitigation efforts in Maryland. Liming has been effectively used to counteract surface-water acidification in parts of Scandinavia, Canada, and the U.S. To date, liming has generally been shown to improve physical and chemical conditions and enhance the biological recovery of aquatic ecosystems affected by acidification.

  9. Effects of lime juice on malaria parasite clearance.

    PubMed

    Adegoke, S A; Oyelami, O A; Olatunya, O S; Adeyemi, L A

    2011-10-01

    One hundred and twenty children with acute uncomplicated malaria who were managed at the children's outpatient department of the Wesley Guild Hospital, Ilesa (a unit of Obafemi Awolowo University Teaching Hospitals' Complex, Ile-Ife, Osun state, Nigeria) were recruited into the study to determine the effects of lime juice on malaria parasite clearance. These children were randomized into treatment with World Health Organization recommended antimalarials (artemisinin combination therapy, ACT) either alone or with lime juice. Nine of them were lost to follow-up, four were in the group that were managed with ACT and lime, and five in the group that were managed on ACT alone. The average (SD) time to achieve >75% reduction in parasite load was significantly lower in patients on ACT and lime; 30.5 ± 2.4 h against 38.6 ± 3.3 h for those on ACT alone (p < 0.001). Also, while a significantly higher proportion of children on antimalarial drugs and lime juice achieved complete parasite clearance by 72 h of therapy (p = 0.007), ten (18.2%) patients without lime had early treatment failure (p = 0.003). There were no side effects with the use of lime juice. It may therefore be inferred, from this preliminary work, that lime juice when used with the appropriate antimalarial may enhance malaria parasite clearance especially in those with uncomplicated malaria.

  10. Engineering Properties of Bentonite Stabilized with Lime and Phosphogypsum

    NASA Astrophysics Data System (ADS)

    Kumar, Sujeet; Dutta, Rakesh Kumar; Mohanty, Bijayananda

    2014-12-01

    Engineering properties such as compaction, unconfined compressive strength, consistency limits, percentage swell, free swell index, the California bearing ratio and the consolidation of bentonite stabilized with lime and phosphogypsum are presented in this paper. The content of the lime and phosphogypsum varied from 0 to 10 %. The results reveal that the dry unit weight and optimum moisture content of bentonite + 8 % lime increased with the addition of 8 % phosphogypsum. The percentage of swell increased and the free swell index decreased with the addition of 8 % phosphogypsum to the bentonite + 8 % lime mix. The unconfined compressive strength of the bentonite + 8 % lime increased with the addition of 8 % phosphogypsum as well as an increase in the curing period up to 14 days. The liquid limit and plastic limit of the bentonite + 8 % lime increased, whereas the plasticity index remained constant with the addition of 8 % phosphogypsum. The California bearing ratio, modulus of subgrade reaction, and secant modulus increased for the bentonite stabilized with lime and phosphogypsum. The coefficient of the consolidation of the bentonite increased with the addition of 8 % lime and no change with the addition of 8 % phosphogypsum.

  11. Lime slurry use at the Industrial Wastewater Pretreatment Facility

    SciTech Connect

    Rice, L.E.; Hughes, R.W.; Baggett, G.

    1996-04-01

    The use of lime slurry at the IWPF demonstrated many benefits. Hazardous chemical use was reduced, solids handling was improved, water quality was enhanced and there has been a cost savings. The lime slurry also enabled the plant to begin treating the soluble oil waste, which we were not able to do in the past.

  12. Investigation of Copper Sorption by Sugar Beet Processing Lime Waste

    EPA Science Inventory

    In the western United States, sugar beet processing for sugar recovery generates a lime-based waste product (~250,000 Mg yr-1) that has little liming value in the region’s calcareous soils. This area has recently experienced an increase in dairy production, with dairi...

  13. Subaerial meteoric calcitization and lithification of high-magnesian calcite muds, Belize

    SciTech Connect

    Mazzullo, S.J.; Bischoff, W.D. )

    1991-03-01

    Holocene ({lt}1000-1500 yrs old) high-magnesian calcite-dominated muddy sediments (1 m thick) on subaerially exposed cays in northern Belize are in the process of being converted to low-magnesian calcite micrite. Mineralogic stabilization and attendant lithification result from interaction of the sediments with meteoric fluids believed to be derived from seasonal upward discharge through subjacent Pleistocene limestones. The initial marine-derived sediments, composed of {gt}85% HMC (and minor skeletal aragonite), consist of mud and associated soritid and miliolid foraminifera both with MgCO{sub 3} content of 11-15 mol%, and isotopic compositions of -1.0 to -2.5{per thousand} PDB (O), 0 to +1.5{per thousand} PDB (C). With depth, lithified LMC crusts appear in the section, and the Mg concentration of the sediments and associated crusts decreases rapidly to 3 mol% or less, with a corresponding isotopic depletion to values approaching -7.0{per thousand} (O) and -5.8{per thousand} (C). Concomitantly there is progressive dissolution of skeletal aragonite in the sediments, reduction of porosity due to cementation by LMC, and in the muds, a decrease in Sr and increase in Mn contents. The resultant petrofabric of these lithified LMC deposits, derived from the alteration of HMC-dominated muds, is characterized by micrite with patches of pore-filling micritic and microsparitic LMC cements. Such a fabric is similar to and can be confused easily with calcitized aragonite-dominated precursor muds, except for the relative rarity in the samples examined of aragonite relicts in component microspar and/or pseudospar.

  14. Durability of base course construction using lime stabilized fly ash and flue gas desulfurization sludge by-product

    SciTech Connect

    Beeghly, J.H.; Amaya, P.J.

    1996-12-31

    Fourteen coal-fired power plants in the Ohio Valley totaling 13,500 MW`s use the magnesium-enhanced lime flue gas desulfurization (FGD) scrubbing process. The discharge of these scrubbers is an aqueous slurry of water containing magnesium and calcium sulfites, and solid particles of calcium sulfite and calcium sulfate. Most of these plants dewater the FGD sludge and mix the 35--45% solids cake with coal fly ash and/or bottom ash and pulverized quicklime to cause a cementitious chemical reaction. This type of pozzolanic and hydration reaction can be described as lime reacting with alumina from the fly ash which in turn react with the calcium sulfite and sulfate FGD waste to form ettringite minerals. With a proper mix design and compaction, the resulting material can be used in a beneficial application as a roller compacted FGD base course (RCFGD) for pavement construction. The mix design procedure for RCFGD is described; it includes extra fly ash and lime materials than that used for landfill disposal to yield additional strength and durability. RCFGD was produced in a portable pug mill and placed trying several at a 10,000 sq. ft. cattle feedlot. Mix design criteria and factors affecting strength and durability are discussed. Results of unconfined compression tests as well as of durability tests are reviewed.

  15. HYDRATE CORE DRILLING TESTS

    SciTech Connect

    John H. Cohen; Thomas E. Williams; Ali G. Kadaster; Bill V. Liddell

    2002-11-01

    The ''Methane Hydrate Production from Alaskan Permafrost'' project is a three-year endeavor being conducted by Maurer Technology Inc. (MTI), Noble, and Anadarko Petroleum, in partnership with the U.S. DOE National Energy Technology Laboratory (NETL). The project's goal is to build on previous and ongoing R&D in the area of onshore hydrate deposition. The project team plans to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope includes drilling and coring one well on Anadarko leases in FY 2003 during the winter drilling season. A specially built on-site core analysis laboratory will be used to determine some of the physical characteristics of the hydrates and surrounding rock. Prior to going to the field, the project team designed and conducted a controlled series of coring tests for simulating coring of hydrate formations. A variety of equipment and procedures were tested and modified to develop a practical solution for this special application. This Topical Report summarizes these coring tests. A special facility was designed and installed at MTI's Drilling Research Center (DRC) in Houston and used to conduct coring tests. Equipment and procedures were tested by cutting cores from frozen mixtures of sand and water supported by casing and designed to simulate hydrate formations. Tests were conducted with chilled drilling fluids. Tests showed that frozen core can be washed out and reduced in size by the action of the drilling fluid. Washing of the core by the drilling fluid caused a reduction in core diameter, making core recovery very difficult (if not impossible). One successful solution was to drill the last 6 inches of core dry (without fluid circulation). These tests demonstrated that it will be difficult to capture core when drilling in permafrost or hydrates without implementing certain safeguards. Among the coring tests was a simulated hydrate formation comprised of coarse, large

  16. Oxidative lime pretreatment of Dacotah switchgrass.

    PubMed

    Falls, Matthew; Sierra-Ramirez, Rocio; Holtzapple, Mark T

    2011-09-01

    Oxidative lime pretreatment increases the enzymatic digestibility of lignocellulosic biomass primarily by removing lignin. In this study, recommended pretreatment conditions (reaction temperature, oxygen pressure, lime loading, and time) were determined for Dacotah switchgrass. Glucan and xylan overall hydrolysis yields (72 h, 15 FPU/g raw glucan) were measured for 105 different reaction conditions involving three different reactor configurations (very short term, short term, and long term). The short-term reactor was the most productive. At the recommended pretreatment condition (120 °C, 6.89 bar O(2), 240 min), it achieved an overall glucan hydrolysis yield of 85.2 g glucan hydrolyzed/100 g raw glucan and an overall xylan yield of 50.1 g xylan hydrolyzed/100 g raw xylan. At this condition, glucan oligomers (1.80 g glucan recovered/100 g glucan in raw biomass) and xylan oligomers (25.20 g xylan recovered/100 g xylan in raw biomass) were recovered from the pretreatment liquor, which compensate for low pretreatment yields.

  17. Elastic and Transport Properties of Steam-Cured Pozzolanic-Lime Rock Composites Upon CO2 Injection

    NASA Astrophysics Data System (ADS)

    Emery, Dan; Vanorio, Tiziana

    2016-04-01

    Understanding the effect of pozzolanic ash-lime reactions on the rock physics properties of the resulting rock microstructure is important for monitoring unrest conditions in volcanic-hydrothermal systems as well as for devising concrete with enhanced performance. By mixing pozzolana ash with lime, the ancient Romans unwittingly incorporated these reactions in the production of their famous concrete. Recently, it has been discovered that a fiber-reinforced, concrete-like rock is forming naturally at depth of 1.5 km within the Campi Flegrei volcanic-hydrothermal systems due to upwelling lime-rich fluids permeating a pozzolana rich layer. This study aims to investigate possible physico-chemical conditions contributing to both enhance and undermine the properties of the subsurface rocks of volcanic-hydrothermal systems and, in turn, build upon those processes that the ancient Romans exploited to create their famous concrete. We prepared samples by mixing the pozzolana volcanic ash, slaked lime, aggregates of Neapolitan Yellow tuff, and seawater from Campi Flegrei in the same ratios as the ancient Romans. To mimic the conditions of the caldera, we used alkaline water from a well in the Campi Flegrei region rich in sulfate, bicarbonate, calcium, potassium, and magnesium ions. Yet, the samples were cured for 28 days in steam-rich environment to favor hydration and hence, enhancing the stability of calcium- alumino-silicate hydrates and setting strength of the rock samples. We measured baseline properties of porosity, permeability, P-wave velocity, and S-wave velocity of the samples as well as imaged the fibrous microstructure. P and S-wave velocities were used to derive bulk, shear, and Young's moduli. Subsequently, samples were injected with an aqueous carbon dioxide, CO2 (aq), solution and the changes in their microstructure and physical properties measured. Exposure of the concrete-like rock samples to CO2 -rich fluid lowers pH below 12.5, thus affecting the stability

  18. Paleoclimatic and paleohydrologic records from secondary calcite: Yucca Mountain, Nevada

    SciTech Connect

    Whelan, J.F.; Stuckless, J.S.; Moscati, R.J.; Vaniman, D.T.

    1994-12-31

    Stable isotope analyses of calcite and opal, fluid inclusion formation conditions and gas compositions, Sr isotope ratios, and REE compositions all support formation of secondary calcite in the unsaturated zone of Yucca Mountain from infiltration of surface-derived (and soil zone buffered) waters of meteoric origin. Detailed sampling of growth-banding preserved by the secondary calcite should provide a record of past variations in the stable isotope chemistry of these infiltrating waters, and, hence, of precipitation at Yucca Mountain, i.e., a proxy of past climate at Yucca Mountain. The precision of this record depends on how well it can be dated. The distribution and texture of secondary calcite occurrences, if mapped in careful detail from existing bore hole samples and underground workings (as exposures become accessible), could provide a time/space map of fracture and fault unsaturated-zone ground water flow-paths during past wetter climates which might prevail in the future with change in climate.

  19. Calcite crystal growth rate inhibition by polycarboxylic acids

    USGS Publications Warehouse

    Reddy, M.M.; Hoch, A.R.

    2001-01-01

    Calcite crystal growth rates measured in the presence of several polycarboxyclic acids show that tetrahydrofurantetracarboxylic acid (THFTCA) and cyclopentanetetracarboxylic acid (CPTCA) are effective growth rate inhibitors at low solution concentrations (0.01 to 1 mg/L). In contrast, linear polycarbocylic acids (citric acid and tricarballylic acid) had no inhibiting effect on calcite growth rates at concentrations up to 10 mg/L. Calcite crystal growth rate inhibition by cyclic polycarboxyclic acids appears to involve blockage of crystal growth sites on the mineral surface by several carboxylate groups. Growth morphology varied for growth in the absence and in the presence of both THFTCA and CPTCA. More effective growth rate reduction by CPTCA relative to THFTCA suggests that inhibitor carboxylate stereochemical orientation controls calcite surface interaction with carboxylate inhibitors. ?? 20O1 Academic Press.

  20. Static Grain Growth in Contact Metamorphic Calcite: A Cathodoluminescence Study.

    NASA Astrophysics Data System (ADS)

    Vogt, B.; Heilbronner, R.; Herwegh, M.; Ramseyer, K.

    2009-04-01

    In the Adamello contact aureole, monomineralic mesozoic limestones were investigated in terms of grain size evolution and compared to results on numerical modeling performed by Elle. The sampled area shows no deformation and therefore represents an appropriate natural laboratory for the study of static grain growth (Herwegh & Berger, 2003). For this purpose, samples were collected at different distances to the contact to the pluton, covering a temperature range between 270 to 630°C. In these marbles, the grain sizes increase with temperature from 5 µm to about 1 cm as one approaches the contact (Herwegh & Berger, 2003). In some samples, photomicrographs show domains of variable cathodoluminescence (CL) intensities, which are interpreted to represent growth zonations. Microstructures show grains that contain cores and in some samples even several growth stages. The cores are usually not centered and the zones not concentric. They may be in touch with grain boundaries. These zonation patterns are consistent within a given aggregate but differ among the samples even if they come from the same location. Relative CL intensities depend on the Mn/Fe ratio. We assume that changes in trace amounts of Mn/Fe must have occurred during the grain size evolution, preserving local geochemical trends and their variations with time. Changes in Mn/Fe ratios can either be explained by (a) locally derived fluids (e.g. hydration reactions of sheet silicate rich marbles in the vicinity) or (b) by the infiltration of the calcite aggregates by externally derived (magmatic?) fluids. At the present stage, we prefer a regional change in fluid composition (b) because the growth zonations only occur at distances of 750-1250 m from the pluton contact (350-450°C). Closer to the contact, neither zonations nor cores were found. At larger distances, CL intensities differ from grain to grain, revealing diagenetic CL patterns that were incompletely recrystallized by grain growth. The role of

  1. Wetland vegetation responses to liming an Adirondack watershed

    SciTech Connect

    Mackun, I.R.

    1993-01-01

    Watershed liming as a long-term mitigation strategy to neutralize lake acidity, from increasing acid deposition, was initiated in North America at Woods Lake in the west central Adirondack region of New York. In October 1989, a dose of 10 MT lime (83.5% CaCO[sub 3]) ha[sup [minus]1] was aerially applied to 48% of the watershed. The wetlands adjacent to Woods Lake showed two distinct community types: one dominated by Chamaedaphne calyculata, and one dominated by graminoids and other herbaceous species. Within two years, liming did not alter the structure of either community type, and changed the cover or frequency of only 6 of 64 individual taxa. Most of these changes occurred in the herbaceous community type. The only strong positive response to liming was a nearly threefold increase in cover of the rhizomatous sedge Cladium mariscoides. The cover of Carex interior and Sphagnum spp. benefited from lime addition, while cover of Drosera intermedia and Muhlenbergia uniflora, and frequency of Hypericum canadense responded negatively to lime. Liming influenced the competitive release of only three taxa, all forbs with small growth forms. The tissue chemistry of foliage and twigs of Myrica gale, Chamaedaphne calyculata, and Carex stricta in the Chamaedaphne calyculata community type clearly illustrated species-specific patterns of nutrient accumulation and allocation both before and after liming. Concentrations of 17 of 20 elements responded to liming, although the responses varied among species and plant parts. Carex foliage was least responsive to liming, and Chamaedaphne twigs were most responsive. Elemental changes in plant tissues will be reflected in litter and many influence long-term nutrient dynamics in the wetland community.

  2. An AFM study of calcite dissolution in concentrated electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Ruiz Agudo, E.; Putnis, C. V.; Putnis, A.; Rodriguez-Navarro, C.

    2009-04-01

    Calcite-solution interactions are of a paramount importance in a range of processes such as the removal of heavy metals, carbon dioxide sequestration, landscape modeling, weathering of building stone and biomineralization. Water in contact with minerals often carries significant amounts of solutes; additionally, their concentration may vary due to evaporation and condensation. It is well known that calcite dissolution is affected dramatically by the presence of such solutes. Here we present investigations on the dissolution of calcite in the presence of different electrolytes. Both bulk (batch reactors) experiments and nanoscale (in situ AFM) techniques are used to study the dissolution of calcite in a range of solutions containing alkaly cations balanced by halide anions. Previous works have indicated that the ionic strength has little influence in calcite dissolution rates measured from bulk experiments (Pokrovsky et al. 2005; Glendhill and Morse, 2004). Contrary to these results, our quantitative analyses of AFM observations show an enhancement of the calcite dissolution rate with increasing electrolyte concentration. Such an effect is concentration-dependent and it is most evident in concentrated solutions. AFM experiments have been carried out in a fluid cell using calcite cleavage surfaces in contact with solutions of simple salts of the alkaly metals and halides at different undersaturations with respect to calcite to try to specify the effect of the ionic strength on etch pit spreading rate and calcite dissolution rate. These results show that the presence of soluble salts may critically affect the weathering of carbonate rocks in nature as well as the decay of carbonate stone in built cultural heritage. References: Pokrosky, O.S.; Golubev, S.V.; Schott, J. Dissolution kinetics of calcite, dolomite and magnesite at 25°C and 0 to 50 atm pCO2. Chemical Geology, 2005, 217 (3-4) 239-255. Glendhill, D.K.; Morse, J.W. Dissolution kinetics of calcite in Na

  3. Strontium Incorporation Into Calcite Generated by Bacterial Ureolysis

    NASA Astrophysics Data System (ADS)

    Fujita, Y.; Ingram, J. A.; Cortez, M. M.; Redden, G. D.; Smith, R. W.

    2002-12-01

    Strontium incorporation into calcite generated by bacterial ureolytic activity was investigated as part of a larger effort to evaluate the use of in situ urea hydrolysis for accelerating co-precipitation of trace metals and radionuclides in contaminated aquifers. 90Sr, a uranium fission product with a half-life of 29 years, is a significant subsurface contaminant at several Department of Energy facilities and could be immobilized using this remediation strategy. Experiments were conducted in a medium designed to simulate the groundwater of the Snake River Plain Aquifer in eastern Idaho, amended with strontium. Initially the solution was undersaturated with respect to calcite. As a model ureolytic organism, we used Bacillus pasteurii, a well-characterized bacterium known for high urease activity and previously shown to induce calcite precipitation in urea-amended medium. To gain information on the effect of the bacterial surfaces, we also looked at precipitation in the presence of a bacterial species that did not hydrolyze urea, as well as in the absence of bacteria. In the absence of bacterial ureolysis, carbonate precipitation was induced by addition of ammonium carbonate. All products were identified as calcite by X-ray diffraction. Strontium uptake was observed in all cases, but was greatest in the system including bacterial ureolysis. Sputter depth element profiling by time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed this finding, showing highest Sr:Ca ratios in the bacterially generated calcite throughout the depth (~350 nm) investigated. Environmental Scanning Electron Microscopy (ESEM) of the solids revealed regular crystals containing the outlines of embedded or entombed bacterial cells, suggesting that calcite precipitated directly on the cell surfaces when present. Analysis by X-ray Absorption Near Edge Spectroscopy (XANES) indicated that in both the biotically and abiotically generated calcites the Sr was incorporated into the calcite

  4. Kinetics and Mechanisms of Calcite Reactions with Saline Waters

    SciTech Connect

    Chapman, Piers; *Morse, John W.

    2010-11-15

    1. Objective The general objective of this research was to determine the kinetics and mechanisms of calcite reactions with saline waters over a wide range of saline water composition, carbon dioxide partial pressure (pCO2), and modest ranges of T and P. This would be done by studying both reaction rates and solubility from changes in solution chemistry. Also, nanoscale observations of calcite surface morphology and composition would be made to provide an understanding of rate controlling mechanisms.

  5. Dynamics of protein hydration water.

    PubMed

    Wolf, M; Emmert, S; Gulich, R; Lunkenheimer, P; Loidl, A

    2015-09-01

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures, and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range. The obtained results prove the bimodality of the hydration shell dynamics. In addition, we find indications of a fragile-to-strong transition of hydration water.

  6. The relative merits of dolomitic and calcitic limestone in detoxifying and revegetating acidic, nickel- and copper-contaminated soils in the Sudbury mining and smelting region of Canada

    SciTech Connect

    McHale, D.; Winterhalder, K.

    1996-12-31

    Soils in the Sudbury mining and smelting region have been rendered phytotoxic and barren by acidification and Particulate metal contamination, but can be detoxified revegetated by the surface application of an growth is better on soil treated ground limestone. On certain barren sites, plant growth is better on soil treated with dolomitic limestone than with calcitic limestone and greenhouse experiments using mung beans (Vigna radiata) have shown superior root and shoot growth on certain contaminated soils when the limestone is dolomitic rather than calcitic. Results of experiments with species used in revegetation (Agrostis gigantea and Lotus corniculatus) suggest that leguminous species are more sensitive to Ca:Mg ratio than grasses, that the plant response to this ratio is greater at lowering liming levels, and that the response is more marked on more toxic soils. The effects of calcium:magnesium ratio of the limestone used in revegetating acidic, metal-contaminated soils are clearly complex, interactive and difficult to interpret. Further studies are needed, but meanwhile it is recommended that the practice of using dolomitic limestone to detoxify barren Sudbury soils be continued, since there is a risk of induced magnesium deficiency at certain sites when calcitic limestone is used.

  7. The differnces between bond lengths in biogenic and geologocal calcite.

    SciTech Connect

    Zlotoyabko, E.; Caspi, E. N.; Fieramosca, J. S.; Von Dreele, R. B.; Marin, F.; Mor, G.; Politi, Y.; Addadi, L.; Weiner, S.

    2010-01-01

    We used high-resolution neutron powder diffraction to accurately measure the atomic positions and bond lengths in biogenic and geological calcite. A special procedure for data analysis was developed in order to take into account the considerable amounts of magnesium present in all the investigated samples. As a result, in biogenic calcite we found some atomic bonds to have significantly different lengths as compared to those in geological calcite, after the contribution of magnesium is accounted for. The maximum effect (elongation up to 0.7%) was found for the C-O bonds. We also analyzed changes in frequencies and spectral widths of normal vibrations of carbonate groups in biogenic calcite (as compared to geological calcite) measured by Raman and Fourier transform IR techniques. Surprisingly, the frequency shifts after subtracting the magnesium contribution are close to zero. At the same time, substantial spectral broadening (up to 1.2%) in biogenic calcite as compared to geological samples was detected. Possible explanations for the experimental findings are discussed.

  8. A novel determination of calcite dissolution kinetics in seawater

    NASA Astrophysics Data System (ADS)

    Subhas, Adam V.; Rollins, Nick E.; Berelson, William M.; Dong, Sijia; Erez, Jonathan; Adkins, Jess F.

    2015-12-01

    We present a novel determination of the dissolution kinetics of inorganic calcite in seawater. We dissolved 13 C -labeled calcite in unlabeled seawater, and traced the evolving δ13 C composition of the fluid over time to establish dissolution rates. This method provides sensitive determinations of dissolution rate, which we couple with tight constraints on both seawater saturation state and surface area of the dissolving minerals. We have determined dissolution rates for two different abiotic calcite materials and three different grain sizes. Near-equilibrium dissolution rates are highly nonlinear, and are well normalized by geometric surface area, giving an empirical dissolution rate dependence on saturation state (Ω) of: This result substantiates the non-linear response of calcite dissolution to undersaturation. The bulk dissolution rate constant calculated here is in excellent agreement with those determined in far from equilibrium and dilute solution experiments. Plots of dissolution versus undersaturation indicates the presence of at least two dissolution mechanisms, implying a criticality in the calcite-seawater system. Finally, our new rate determination has implications for modeling of pelagic and seafloor dissolution. Nonlinear dissolution kinetics in a simple 1-D lysocline model indicate a possible transition from kinetic to diffusive control with increasing water depth, and also confirm the importance of respiration-driven dissolution in setting the shape of the calcite lysocline.

  9. Influence of different additives on the reaction between hydrated lime and sulfur dioxide

    SciTech Connect

    Cunill, F.; Izquierdo, J.F.; Martinez, J.C.; Tejero, J.; Querol, J. )

    1991-11-01

    Five commercial calcium hydroxides were tested in a fixed-bed reactor for SO{sub 2} removal at bag-filter conditions. Small amounts of different additives (fly ash, NaOH, NaCl and CaCl{sub 2}) were added to the commercial Ca(OH){sub 2} which showed the greatest reactivity respect to SO{sub 2} (by a drying process). Fly ash performance was negative whereas the rest of additives enhanced the desulfurization power of the Ca(OH){sub 2}, specially NaOH (due to its basic and deliquescent character) and CaCl{sub 2} (by its delilquescence). CaCl{sub 2} has been the best additive tested at the used experimental conditions.

  10. Influence of water vapour and carbon dioxide on free lime during storage at 80 °C, studied by Raman spectroscopy.

    PubMed

    Dubina, E; Korat, L; Black, L; Strupi-Šuput, J; Plank, J

    2013-07-01

    Micro-Raman spectroscopy has been used to follow the reaction of free lime (CaO) exposed for 24h to moist air at 80 °C under conditions of different relative humidities (10-80% RH). X-ray diffraction and SEM imaging were applied as complementary techniques. The conversion of lime to calcium hydroxide and its subsequent carbonation to various calcium carbonate polymorphs was found to strongly depend on the relative humidity. At low RH (10-20%), only Raman spectroscopy revealed the formation of early amorphous CaCO3 which in the XRD patterns was detected only at ≥40% RH. However, XRD analysis could identify the crystalline polymorphs formed at higher relative humidities. Thus, between 20 and 60% RH, all three CaCO3 polymorphs (calcite, aragonite and vaterite) were observed via XRD whereas at high relative humidity (80%), calcite was the predominant reaction product. The results demonstrate the usefulness of Raman spectroscopy in the study of minor cement constituents and their reaction products on air, especially of amorphous character.

  11. [Hydration in clinical practice].

    PubMed

    Maristany, Cleofé Pérez-Portabella; Segurola Gurruchaga, Hegoi

    2011-01-01

    Water is an essential foundation for life, having both a regulatory and structural function. The former results from active and passive participation in all metabolic reactions, and its role in conserving and maintaining body temperature. Structurally speaking it is the major contributer to tissue mass, accounting for 60% of the basis of blood plasma, intracellular and intersticial fluid. Water is also part of the primary structures of life such as genetic material or proteins. Therefore, it is necessary that the nurse makes an early assessment of patients water needs to detect if there are signs of electrolyte imbalance. Dehydration can be a very serious problem, especially in children and the elderly. Dehydrations treatment with oral rehydration solution decreases the risk of developing hydration disorders, but even so, it is recommended to follow preventive measures to reduce the incidence and severity of dehydration. The key to having a proper hydration is prevention. Artificial nutrition encompasses the need for precise calculation of water needs in enteral nutrition as parenteral, so the nurse should be part of this process and use the tools for calculating the patient's requirements. All this helps to ensure an optimal nutritional status in patients at risk. Ethical dilemmas are becoming increasingly common in clinical practice. On the subject of artificial nutrition and hydration, there isn't yet any unanimous agreement regarding hydration as a basic care. It is necessary to take decisions in consensus with the health team, always thinking of the best interests of the patient.

  12. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  13. Mechanical and leaching behaviour of slag-cement and lime-activated slag stabilised/solidified contaminated soil.

    PubMed

    Kogbara, Reginald B; Al-Tabbaa, Abir

    2011-05-01

    Stabilisation/solidification (S/S) is an effective technique for reducing the leachability of contaminants in soils. Very few studies have investigated the use of ground granulated blast furnace slag (GGBS) for S/S treatment of contaminated soils, although it has been shown to be effective in ground improvement. This study sought to investigate the potential of GGBS activated by cement and lime for S/S treatment of a mixed contaminated soil. A sandy soil spiked with 3000mg/kg each of a cocktail of heavy metals (Cd, Ni, Zn, Cu and Pb) and 10,000mg/kg of diesel was treated with binder blends of one part hydrated lime to four parts GGBS (lime-slag), and one part cement to nine parts GGBS (slag-cement). Three binder dosages, 5, 10 and 20% (m/m) were used and contaminated soil-cement samples were compacted to their optimum water contents. The effectiveness of the treatment was assessed using unconfined compressive strength (UCS), permeability and acid neutralisation capacity (ANC) tests with determination of contaminant leachability at the different acid additions. UCS values of up to 800kPa were recorded at 28days. The lowest coefficient of permeability recorded was 5×10(-9)m/s. With up to 20% binder dosage, the leachability of the contaminants was reduced to meet relevant environmental quality standards and landfill waste acceptance criteria. The pH-dependent leachability of the metals decreased over time. The results show that GGBS activated by cement and lime would be effective in reducing the leachability of contaminants in contaminated soils.

  14. Photoinduced synthesis of single-digit micrometer-size spheroidal calcite composites in the presence of partially hydrolyzed poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Nishio, Takashi; Naka, Kensuke

    2015-06-01

    Photoinduced crystallization of calcium carbonate (CaCO3), which was based on the photodecarboxylation of ketoprofen (KP, 2-(3-benzoylphyenyl)propionic acid) under alkaline conditions of pH 8.4 and 10 was studied for preparation of CaCO3 composite particles in single-digit micrometer-sizes. In this method, a homogeneous solution comprising KP, calcium chloride, ammonia, and partially hydrolyzed poly(vinyl alcohol) (PVAPS, degree of saponification: 86.5-89.0 mol%) was used as a precursor solution and was exposed to ultraviolet (UV) irradiation for different time periods. After the UV irradiation for 50 min, calcite spheroids in single-digit micrometer-sizes were obtained as major products at pH 8.4. The obtained calcite spheroids contained organic components of about 10 wt%. The comparison of the characteristics of the CaCO3 obtained at pH 8.4 and 10 suggests that the nucleation and crystallization of both vaterite and calcite continuously took place in a moderated supersaturation owing to the CO2 hydration equilibrium as long as the photodecarboxylation of KP continued. Consequently, the aggregation-based crystal growth in the presence of PVAPS seemed to enable the formation of the spheroidal composites of calcite in single-digit micrometer-sizes.

  15. Lime kiln source characterization: Lime manufacturing industry Fourier transform infrared spectroscopy. Final report

    SciTech Connect

    Toney, M.L.

    1999-07-01

    The purpose of this testing program is to obtain uncontrolled and controlled hydrogen chloride (HCl) and speciated hydrocarbon Hazardous Air Pollutants (HAPs) emissions data from lime production plants to support a national emission standard for hazardous air pollutants (NESHAP). This report presents data from the Fourier Transform Infrared Spectroscopy (FTIR) measurements. FTIR source testing was conducted for the following purposes: Quantify HCl emission levels; and Gather screening (i.e., qualitative) data on other HAP emissions.

  16. Performance of lime-BHA solidified plating sludge in the presence of Na2SiO3 and Na2CO3.

    PubMed

    Piyapanuwat, Rungroj; Asavapisit, Suwimol

    2011-09-01

    This research investigated the performance of lime-BHA (black rice husk ash) solidified plating sludge with 2 wt% NaO from Na(2)SiO(3) and Na(2)CO(3) at the level of 0, 30 and 50 wt%. The sludge was evaluated for strength development, leachability, solution chemistry and microstructure. The lime-BHA solidified plating sludge with Na(2)SiO(3) and Na(2)CO(3) had higher early strength when compared to the control. The addition of Na(2)SiO(3) and Na(2)CO(3) increased the OH(-) concentration and decreased the Ca(2+) and heavy metal ions in solution after the first minute. The XRD patterns showed that the addition of Na(2)SiO(3) resulted in the formation of calcium silicate hydrates, while the addition of Na(2)CO(3) resulted in CaCO(3). The heavy metals from the plating sludge, especially Zn, were immobilized in calcium zincate and calcium zinc silicate forms for the lime-BHA with and without Na(2)SiO(3) solidified wastes, while samples with Na(2)CO(3) contained Zn that was fixed in the form of CaZnCO(3). The cumulative leaching of Fe, Cr and Zn from the lime-BHA solidified plating sludge decreased significantly when activators were added, especially Na(2)CO(3).

  17. Controls on Calcite Solubility in Metamorphic and Magmatic Fluids

    NASA Astrophysics Data System (ADS)

    Manning, C. E.; Eguchi, J.; Galvez, M.

    2015-12-01

    Calcite is an important hydrothermal alteration product in a wide range of environments. The role of calcite in hydrothermal alteration depends on its solubility in geologic fluids, especially H2O. At ambient T and P, calcite solubility is low and it exhibits well-known declining, or "reverse", solubility with rising T. However, experimental and theoretical studies show that increasing P yields higher solubility and restricts the region of reverse solubility behavior to higher temperature. At 0.2 GPa the reverse solubility region lies at T>600°C; at 0.5 GPa, >800°C. Thus, whereas calcite possesses relatively low solubility in pure H2O in shallow hydrothermal systems (typically <10 ppm C), it is substantially more soluble at conditions of middle and lower crustal metamorphism and magmatism, reaching concentrations ≥1000 ppm. At the higher P of subduction zones, aragonite solubility in H2O is even greater. Thus, neglecting other solubility controls, calcite precipitation is favored as crustal fluids cool and/or decompress. However, the solubility of calcite in H2O also depends strongly on other solutes, pH, and fO2. Sources of alkalinity decrease calcite solubility. In contrast, sources of acidity such as CO2 and Cl increase solubility. Crustal fluids can be enriched in alkali halides such as NaCl. Calcite solubility increases with increasing salt content at a given P and T. From approximately seawater salinity to salt saturation, the fluid behaves as a dilute molten salt and calcite solubility increases as the square of the salt mole fraction regardless of the alkali (Li, Na, K, Cs) or halogen (F, Cl, Br, I) considered. Similar behavior is seen in mixed salt solutions. At lower salinities, solubility behavior is as expected in dilute electrolyte solutions. The transition from dilute electrolyte to molten salt is fundamental to the properties of crustal fluids. Reduction of carbonate species or CO2 in the fluid to CH4, which is common during serpentinization of

  18. Phytochemical fingerprints of lime honey collected in serbia.

    PubMed

    Gašić, Uroš; Šikoparija, Branko; Tosti, Tomislav; Trifković, Jelena; Milojković-Opsenica, Dušanka; Natić, Maja; Tešić, Živoslav

    2014-01-01

    Composition of phenolic compounds and the sugar content were determined as the basis for characterization of lime honey from Serbia. Particular attention was given to differences in phytochemical profiles of ripe and unripe lime honey and lime tree nectar. Melissopalynological analysis confirmed domination of Tilia nectar in all analyzed samples. Phenolic acids, abscisic acid, flavonoids, and flavonoid glycosides were determined by means of ultra-HPLC coupled with a hybrid mass spectrometer (UHPLC-OrbiTrap). Sugar content was determined using high-performance anion-exchange chromatography with amperometric detection. Similar phenolic compounds characterized unripe and ripe honeys, while the lime tree nectar profile showed notable differences. Compared to lime tree nectar, a high amount of chrysin, pinocembrin, and galangin were detected in both ripe and unripe lime honey. Fructose and glucose were the major constituents of all investigated samples, and amounts were within the limits established by European Union legislation. Sucrose content in the nectar sample was up to two-fold higher when compared to all honey samples. Isomaltose and gentiobiose with turanose content were different in analyzed production stages of lime honey.

  19. Effect of lime concentration on gelatinized maize starch dispersions properties.

    PubMed

    Lobato-Calleros, C; Hernandez-Jaimes, C; Chavez-Esquivel, G; Meraz, M; Sosa, E; Lara, V H; Alvarez-Ramirez, J; Vernon-Carter, E J

    2015-04-01

    Maize starch was lime-cooked at 92 °C with 0.0-0.40% w/w Ca(OH)2. Optical micrographs showed that lime disrupted the integrity of insoluble remnants (ghosts) and increased the degree of syneresis of the gelatinized starch dispersions (GSD). The particle size distribution was monomodal, shifting to smaller sizes and narrower distributions with increasing lime concentration. X-ray patterns and FTIR spectra showed that crystallinity decreased to a minimum at lime concentration of 0.20% w/w. Lime-treated GSD exhibited thixotropic and viscoelastic behaviour. In the linear viscoelastic region the storage modulus was higher than the loss modulus, but a crossover between these moduli occurred in the non-linear viscoelastic region. The viscoelastic properties decreased with increased lime concentration. The electrochemical properties suggested that the amylopectin-rich remnants and the released amylose contained in the continuous matrix was firstly attacked by calcium ions at low lime levels (<0.20% w/w), disrupting the starch gel microstructure.

  20. EPA compares lime, limestone FGD systems

    SciTech Connect

    Not Available

    1984-05-28

    According to a recent report by the EPA, flue gas desulfurization processes using lime require lower capital investments than limestone processes, and at low coal sulfur contents, annual revenue requirements are also lower. But this advantage disappears when coal sulfur content rises above 2%. A study of FGD systems performed by TVA evaluated absorber types, forced oxidation and the use of additives. The study compared processes with forced oxidation and landfill disposal, and found these have lower capital investments than processes without forced oxidation using pond disposal. Using additives in the limestone processes reduces both capital investment and annual revenue requirements. Adipic acid seems more efficient than MgO. Comparing absorber types, EPA found that for all systems, the TCA process was lowest in capital investment and annual revenue requirements.

  1. Leaching behavior of lime-fly ash mixtures

    SciTech Connect

    Daniels, J.L.; Das, G.P.

    2006-01-15

    As part of a larger investigation that included numerical and field-based components, the use of lime to reduce the leachability of a coal combustion fly ash was evaluated in the laboratory. The focus of this paper is on the experimental assessment of lime-fly ash leachability through sequential leach (SL), freeze-thaw (FT), and wet-dry (WD) leaching as well as multileachant sequential extraction (SE) tests. The results suggest that lime addition reduces the leachability for Cd, Se, and to some extent As. They also suggest that Cr is rendered more leachable with increasing lime content, for the conditions and low levels tested. It appears that there is a threshold lime content ({gt} 1.0%) that must be exceeded prior to reducing the leachability of As and Se. In particular, this threshold likely corresponds to the level at which appreciable cementitious reactions have developed. For example, in the case of As after the first cycle of leaching, the concentration was below the reporting limit (10 {mu} g/L) for 0% lime. However, at 0.5% lime amendment, the leached concentration increased to nearly 50 {mu} g/L. Subsequent lime additions reduced this concentration. No such threshold was observed for Cd leachability as was expected as a direct consequence of hydroxide precipitation, which is well established under the measured pH conditions. As such, Cd mobility is insensitive to the extent to which cementitious reactions are initiated. Overall, the results suggest that while lime stabilization may be effective for reducing leachability, sufficient amounts must be added; otherwise, the leachability of some constituents can actually be exacerbated.

  2. Defluoridation of drinking water by boiling with brushite and calcite.

    PubMed

    Larsen, M J; Pearce, E I F

    2002-01-01

    Existing methods for defluoridating drinking water involve expensive high technology or are slow, inefficient and/or unhygienic. A new method is now suggested, encompassing brushite and calcite suspension followed by boiling. Our aim was to examine the efficiency of the method and the chemical reactions involved. Brushite, 0.3-0.5 g, and an equal weight of calcite were suspended in 1 litre water containing 5-20 ppm fluoride. The suspensions were boiled in an electric kettle, left to cool and the calcium salts to sediment. Solution ion concentrations were determined and sediments were examined by X-ray diffraction. In distilled water initially containing 5, 10 and 20 ppm fluoride the concentration was reduced to 0.06, 0.4 and 5.9 ppm, respectively. Using Aarhus tap water which contained 2.6 mmol/l calcium the final concentrations were 1.2, 2.5 and 7.7 ppm, respectively, and runs without calcite gave results similar to those with calcite. Without boiling the fluoride concentration remained unaltered, as did the brushite and calcite salts, despite occasional agitation by hand. All solutions were supersaturated with respect to fluorapatite and hydroxyapatite and close to saturation with respect to brushite. Boiling produced well-crystallised apatite and traces of calcite, while boiling of brushite alone left a poorly crystallised apatite. We conclude that boiling a brushite/calcite suspension rapidly converts the two salts to apatite which incorporates fluoride if present in solution, and that this process may be exploited to defluoridate drinking water.

  3. On the complex conductivity signatures of calcite precipitation

    SciTech Connect

    Wu, Yuxin; Hubbard, Susan; Williams, Kenneth Hurst; Ajo-Franklin, Jonathan

    2009-11-01

    Calcite is a mineral phase that frequently precipitates during subsurface remediation or geotechnical engineering processes. This precipitation can lead to changes in the overall behavior of the system, such as flow alternation and soil strengthening. Because induced calcite precipitation is typically quite variable in space and time, monitoring its distribution in the subsurface is a challenge. In this research, we conducted a laboratory column experiment to investigate the potential of complex conductivity as a mean to remotely monitor calcite precipitation. Calcite precipitation was induced in a glass bead (3 mm) packed column through abiotic mixing of CaCl{sub 2} and Na{sub 2}CO{sub 3} solutions. The experiment continued for 12 days with a constant precipitation rate of {approx}0.6 milimole/d. Visual observations and scanning electron microscopy imaging revealed two distinct phases of precipitation: an earlier phase dominated by well distributed, discrete precipitates and a later phase characterized by localized precipitate aggregation and associated pore clogging. Complex conductivity measurements exhibited polarization signals that were characteristic of both phases of calcite precipitation, with the precipitation volume and crystal size controlling the overall polarization magnitude and relaxation time constant. We attribute the observed responses to polarization at the electrical double layer surrounding calcite crystals. Our experiment illustrates the potential of electrical methods for characterizing the distribution and aggregation state of nonconductive minerals like calcite. Advancing our ability to quantify geochemical transformations using such noninvasive methods is expected to facilitate our understanding of complex processes associated with natural subsurface systems as well as processes induced through engineered treatments (such as environmental remediation and carbon sequestration).

  4. Effect of microstructure and microchemistry on improvement of hydration and slag attack resistance of ilmenite-doped refractory limestone

    NASA Astrophysics Data System (ADS)

    Soltan, Abdel Monem; Serry, Mohamed

    2015-02-01

    This work studies densification, resistance to hydration and slag attack of 0.0-2.0 wt% ilmenite-doped lime refractories in relation to their thermal equilibrium and microfabric after firing at 1,400-1,700 °C. XRF, XRD, SEM-EDAX, transmitted light microscopy and mercury intrusion methods were used to characterize the fired samples. The ternary diagram CaO-C2S-C4AF was applied to the thermal equilibrium data. The rates of hydration and attack by steel-slag were also assessed using cathode-luminescence microscope. Doping limestone with 0.5 wt% ilmenite leads maximizes the rate of densification after firing for 2 h at 1,600 °C. A direct-bonded CaO-CaO network is found in the doped sample with separated islands of Ca-silicate, alumino-ferrite and TiO2-rich Ca, Mg- solid solutions all filling the pores and triple points of the lime grains. Due to the dense microstructure of the doped sample with the direct-bonded lime grains, hydration and slag-attack resistance are enhanced compared with the un-doped sample.

  5. Regeneration of lime from sulfates for fluidized-bed combustion

    DOEpatents

    Yang, Ralph T.; Steinberg, Meyer

    1980-01-01

    In a fluidized-bed combustor the evolving sulfur oxides are reacted with CaO to form calcium sulfate which is then decomposed in the presence of carbonaceous material, such as the fly ash recovered from the combustion, at temperatures of about 900.degree. to 1000.degree. C., to regenerate lime. The regenerated lime is then recycled to the fluidized bed combustor to further react with the evolving sulfur oxides. The lime regenerated in this manner is quite effective in removing the sulfur oxides.

  6. Modeling the evolution of complex conductivity during calcite precipitation on glass beads

    NASA Astrophysics Data System (ADS)

    Leroy, Philippe; Li, Shuai; Jougnot, Damien; Revil, André; Wu, Yuxin

    2017-01-01

    SUMMARYWhen pH and alkalinity increase, <span class="hlt">calcite</span> frequently precipitates and hence modifies the petrophysical properties of porous media. The complex conductivity method can be used to directly monitor <span class="hlt">calcite</span> precipitation in porous media because it is sensitive to the evolution of the mineralogy, pore structure and its connectivity. We have developed a mechanistic grain polarization model considering the electrochemical polarization of the Stern and diffuse layer surrounding <span class="hlt">calcite</span> particles. Our complex conductivity model depends on the surface charge density of the Stern layer and on the electrical potential at the onset of the diffuse layer, which are computed using a basic Stern model of the <span class="hlt">calcite</span>/water interface. The complex conductivity measurements of Wu et al. (2010) on a column packed with glass beads where <span class="hlt">calcite</span> precipitation occurs are reproduced by our surface complexation and complex conductivity models. The evolution of the size and shape of <span class="hlt">calcite</span> particles during the <span class="hlt">calcite</span> precipitation experiment is estimated by our complex conductivity model. At the early stage of the <span class="hlt">calcite</span> precipitation experiment, modeled particles sizes increase and <span class="hlt">calcite</span> particles flatten with time because <span class="hlt">calcite</span> crystals nucleate at the surface of glass beads and grow into larger <span class="hlt">calcite</span> grains around glass beads. At the later stage of the <span class="hlt">calcite</span> precipitation experiment, modeled sizes and cementation exponents of <span class="hlt">calcite</span> particles decrease with time because large <span class="hlt">calcite</span> grains aggregate over multiple glass beads, a percolation threshold is achieved, and small and discrete <span class="hlt">calcite</span> crystals polarize.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMOS22B..05R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMOS22B..05R"><span>Preferential accumulation of gas <span class="hlt">hydrate</span> in the Andaman accretionary wedge and relationship to anomalous porosity preservation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rose, K.; Torres, M. E.; Johnson, J. E.; Hong, W.; Giosan, L.; Solomon, E. A.; Kastner, M.; Cawthern, T.; Long, P.; Schaef, T.</p> <p>2015-12-01</p> <p>In the marine environment, sediments in the gas <span class="hlt">hydrate</span> stability zone often correspond to slope and basin settings. These settings are dominantly composed of fine-grained silt and clay lithofacies with typically low vertical permeability, and pore fluids frequently under-saturated with respect to methane. As a result, the pressure-temperature conditions requisite for a GHSZ to be present occur widely worldwide across marine settings, however, the distribution of gas <span class="hlt">hydrate</span> in these settings is neither ubiquitous nor uniform. This study uses sediment core and borehole related data recovered by drilling at Site 17 in the Andaman Sea during the Indian National Gas <span class="hlt">Hydrate</span> Program Expedition 1 in 2006, to investigate reservoir-scale controls on gas <span class="hlt">hydrate</span> distribution. In particular, this study finds that conditions beyond reservoir pressure, temperature, salinity, and gas concentration, appear to influence the concentration of gas <span class="hlt">hydrate</span> in host sediments. Using field-generated datasets along with newly acquired sedimentology, physical property, imaging and geochemical data with mineral saturation and ion activity products of key mineral phases such as amorphous silica and <span class="hlt">calcite</span>, we document the presence and nature of secondary precipitates that contributed to anomalous porosity preservation at Site 17 in the Andaman Sea. This study demonstrates the importance of grain-scale subsurface heterogeneities in controlling the occurrence and distribution of concentrated gas <span class="hlt">hydrate</span> accumulations in marine sediments, and document the importance that increased permeability and enhanced porosity play in supporting gas concentrations sufficient to support gas <span class="hlt">hydrate</span> formation. This illustrates the complex balance and lithology-driven controls on <span class="hlt">hydrate</span> accumulations of higher concentrations and offers insights into what may control the occurrence and distribution of gas <span class="hlt">hydrate</span> in other sedimentary settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B21G..08D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B21G..08D"><span><span class="hlt">Calcite</span> and Picocyanobacteria in Lakes: Factors Affecting Their Interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dittrich, M.; Obst, M.; Mavrocordatos, D.</p> <p>2003-12-01</p> <p><span class="hlt">Calcites</span> build large deposits which have been observed in the rock record throughout geological time at various localities around the globe. Carbonate deposits have affected atmospheric carbon dioxide concentration. As it has been generally accepted, inorganic precipitation represents a source of carbon dioxide on short geological time scales and a sink of inorganic carbon at long time scales from millions to thousands of millions years. However, recent research indicates that <span class="hlt">calcite</span> deposits may result from microbial calcification instead of inorganic precipitation. In this case the process may reduce atmospheric carbon dioxide on geologically short time scales. Thus the effect of carbonate sediment deposition on global carbon cycling depends on the origin of carbonate. Thus it is essential to understand the cause and the key parameters affecting <span class="hlt">calcite</span> precipitation. The role of algae and bacteria in <span class="hlt">calcite</span> formation in lakes has not been evaluated in detail. Some evidence, however, exists supporting precipitation of calcium carbonate by microbes as the origin of whiting. Several field studies on lakes have also produced puzzling results: The peaks of algal blooms were often not found at the same time as precipitation events of <span class="hlt">calcite</span>. We suspect that parts of the discrepancies in the interpretation of field observations are due to the activity of autotrophic picoplankton. The unicellular autotrophic picoplankton (APP) is a ubiquitous component of pelagic ecosystems. But it has often been overlooked due to its small cell size of 0.2 - 2 μ m in diameter. Coccoid picocyanobacteria of the Synechococcus-type dominate the picoplankton community in most oligotrophic systems. Recently, laboratory experiments and field observations suggested that APP may play an important role in <span class="hlt">calcite</span> precipitation. The aim of this study was to examine the influence of environmental factors such as saturation state, concentration of different dissolved ions and characteristics of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.192...70R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192...70R"><span>Hydrochemical controls on aragonite versus <span class="hlt">calcite</span> precipitation in cave dripwaters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rossi, Carlos; Lozano, Rafael P.</p> <p>2016-11-01</p> <p>Despite the paleoclimatic relevance of primary <span class="hlt">calcite</span> to aragonite transitions in stalagmites, the relative role of fluid Mg/Ca ratio, supersaturation and CO32- concentration in controlling such transitions is still incompletely understood. Accordingly, we have monitored the hydrochemistry of 50 drips and 8 pools that are currently precipitating <span class="hlt">calcite</span> and/or aragonite in El Soplao and Torca Ancha Caves (N. Spain), investigating the mineralogy and geochemistry of the CaCO3 precipitates on the corresponding natural speleothem surfaces. The data reveal that, apart from possible substrate effects, dripwater Mg/Ca is the only obvious control on CaCO3 polymorphism in the studied stalagmites and pools, where <span class="hlt">calcite</span>- and aragonite-precipitating dripwaters are separated by an initial (i.e. at stalactite tips) Mg/Ca threshold at ≈1.1 mol/mol. Within the analyzed ranges of pH (8.2-8.6), CO32- concentration (1-6 mg/L), supersaturation (SIaragonite: 0.08-1.08; SIcalcite: 0.23-1.24), drip rate (0.2-81 drops/min) and dissolved Zn (6-90 μg/L), we observe no unequivocal influence of these parameters on CaCO3 mineralogy. Despite the almost complete overlapping supersaturations of <span class="hlt">calcite</span>- and aragonite-precipitating waters, the latter are on average less supersaturated because the waters having Mg/Ca above ∼1.1 have mostly achieved such high ratios by previously precipitating <span class="hlt">calcite</span>. Both <span class="hlt">calcite</span> and aragonite precipitated at or near oxygen isotopic equilibrium, and Mg incorporation into <span class="hlt">calcite</span> was consistent with literature-based predictions, indicating that in the studied cases CaCO3 precipitation was not significantly influenced by strong kinetic effects. In the studied cases, the <span class="hlt">calcites</span> that precipitate at ∼11 °C from dripwaters with initial Mg/Ca approaching ∼1.1 incorporate ∼5 mol% MgCO3, close to the published value above which <span class="hlt">calcite</span> solubility exceeds aragonite solubility, suggesting that aragonite precipitation in high-relative-humidity caves is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AcSpA.117..158S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AcSpA.117..158S"><span>A Raman spectroscopic comparison of <span class="hlt">calcite</span> and dolomite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, Junmin; Wu, Zeguang; Cheng, Hongfei; Zhang, Zhanjun; Frost, Ray L.</p> <p>2014-01-01</p> <p>Raman spectroscopy was used to characterize and differentiate the two minerals <span class="hlt">calcite</span> and dolomite and the bands related to the mineral structure. The (CO3)2- group is characterized by four prominent Raman vibrational modes: (a) the symmetric stretching, (b) the asymmetric deformation, (c) asymmetric stretching and (d) symmetric deformation. These vibrational modes of the <span class="hlt">calcite</span> and dolomite were observed at 1440, 1088, 715 and 278 cm-1. The significant differences between the minerals <span class="hlt">calcite</span> and dolomite are observed by Raman spectroscopy. <span class="hlt">Calcite</span> shows the typical bands observed at 1361, 1047, 715 and 157 cm-1, and the special bands at 1393, 1098, 1069, 1019, 299, 258 and 176 cm-1 for dolomite are observed. The difference is explained on the basis of the structure variation of the two minerals. <span class="hlt">Calcite</span> has a trigonal structure with two molecules per unit cell, and dolomite has a hexagonal structure. This is more likely to cause the splitting and distorting of the carbonate groups. Another cause for the difference is the cation substituting for Mg in the dolomite mineral.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.6903M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.6903M"><span>Microstructures and elastic properties of sheared <span class="hlt">calcite</span> flowstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitrovic, Ivanka; Grasemann, Bernhard; Plan, Lukas; Tesei, Telemaco; Baron, Ivo</p> <p>2016-04-01</p> <p>Flowstone is a monomineralic rock precipitated along cave walls and floors, composed of columnar centimeter-scale <span class="hlt">calcite</span> crystals with strong growth orientation perpendicular to the growth surface. Broken and scratched flowstone can serve as evidence for active faulting and has been found in several alpine caves in Austria. In order to understand the fault mechanics, and associated potential earthquake hazard, experimentally deformed flowstone is studied using microstructural analysis and EBSD-measured physical properties of <span class="hlt">calcite</span> crystals. For that purpose, we have performed sliding experiments using a rock deformation biaxial apparatus on rectangular blocks of flowstone that were sheared perpendicular to the <span class="hlt">calcite</span> growth direction. The experiments were performed under room conditions, with sub-seismic sliding velocity (0.001-0.01 mm/s) and constant effective normal stress (3-10 MPa). The deformed samples show diverse brittle features, including high fracture density, the development of <span class="hlt">calcite</span>-rich fault gouge with Riedel shears within a foliated cataclasite, and drastic grain size reduction down to nm-scale grains. The dominant plastic microstructure is mechanical twinning. Due to the strong growth orientation of <span class="hlt">calcite</span> in flowstone, crystals can be bent due to shearing. We examine the bending by applying orientation distribution, Schmid factor and elasticity tensor calculations using MTEX Toolbox from EBSD data. In this unique case the flowstone deformation experiments bridge the gap between single crystal and rock powder experiments. This study is supported by the Austrian Science Foundation: SPELEOTECT project (P25884-N29).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23988531','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23988531"><span>A Raman spectroscopic comparison of <span class="hlt">calcite</span> and dolomite.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Junmin; Wu, Zeguang; Cheng, Hongfei; Zhang, Zhanjun; Frost, Ray L</p> <p>2014-01-03</p> <p>Raman spectroscopy was used to characterize and differentiate the two minerals <span class="hlt">calcite</span> and dolomite and the bands related to the mineral structure. The (CO3)(2-) group is characterized by four prominent Raman vibrational modes: (a) the symmetric stretching, (b) the asymmetric deformation, (c) asymmetric stretching and (d) symmetric deformation. These vibrational modes of the <span class="hlt">calcite</span> and dolomite were observed at 1440, 1088, 715 and 278 cm(-1). The significant differences between the minerals <span class="hlt">calcite</span> and dolomite are observed by Raman spectroscopy. <span class="hlt">Calcite</span> shows the typical bands observed at 1361, 1047, 715 and 157 cm(-1), and the special bands at 1393, 1098, 1069, 1019, 299, 258 and 176 cm(-1) for dolomite are observed. The difference is explained on the basis of the structure variation of the two minerals. <span class="hlt">Calcite</span> has a trigonal structure with two molecules per unit cell, and dolomite has a hexagonal structure. This is more likely to cause the splitting and distorting of the carbonate groups. Another cause for the difference is the cation substituting for Mg in the dolomite mineral.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JChPh.145u1705W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JChPh.145u1705W"><span>Overview: Nucleation of clathrate <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.</p> <p>2016-12-01</p> <p>Molecular level knowledge of nucleation and growth of clathrate <span class="hlt">hydrates</span> is of importance for advancing fundamental understanding on the nature of water and hydrophobic <span class="hlt">hydrate</span> formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when <span class="hlt">hydrate</span> structures nucleate will be tremendously beneficial for the development of sustainable <span class="hlt">hydrate</span> management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of <span class="hlt">hydrate</span> nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to <span class="hlt">hydrates</span>. <span class="hlt">Hydrate</span> nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various <span class="hlt">hydrate</span> nucleation hypotheses and <span class="hlt">hydrate</span> nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on <span class="hlt">hydrate</span> nucleation are discussed in detail followed by potential future research directions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110024019','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110024019"><span>Methane Clathrate <span class="hlt">Hydrate</span> Prospecting</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Duxbury, N.; Romanovsky, V.</p> <p>2003-01-01</p> <p>A method of prospecting for methane has been devised. The impetus for this method lies in the abundance of CH4 and the growing shortages of other fuels. The method is intended especially to enable identification of subpermafrost locations where significant amounts of methane are trapped in the form of methane gas <span class="hlt">hydrate</span> (CH4(raised dot)6H2O). It has been estimated by the U.S. Geological Survey that the total CH4 resource in CH4(raised dot) 6H2O exceeds the energy content of all other fossil fuels (oil, coal, and natural gas from non-<span class="hlt">hydrate</span> sources). Also, CH4(raised dot)6H2O is among the cleanest-burning fuels, and CH4 is the most efficient fuel because the carbon in CH4 is in its most reduced state. The method involves looking for a proxy for methane gas <span class="hlt">hydrate</span>, by means of the combination of a thermal-analysis submethod and a field submethod that does not involve drilling. The absence of drilling makes this method easier and less expensive, in comparison with prior methods of prospecting for oil and natural gas. The proposed method would include thermoprospecting in combination with one more of the other non-drilling measurement techniques, which could include magneto-telluric sounding and/or a subsurface-electrical-resistivity technique. The method would exploit the fact that the electrical conductivity in the underlying thawed region is greater than that in the overlying permafrost.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5381687','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5381687"><span>Sulfur dioxide removal from gases using a modified <span class="hlt">lime</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lee, Y.J.; Benson, L.B.</p> <p>1992-01-21</p> <p>This patent describes improvement in a process for removing sulfur dioxide from combustion gases by contacting the gases in a wet scrubbing unit with an aqueous scrubbing slurry, containing calcium components, for the removal of the sulfur dioxide, the calcium components provided in the slurry by adding aqueous slaked <span class="hlt">lime</span> thereto, and a portion of the effluent from the scrubbing unit, containing calcium sulfite solids, is clarified to remove calcium sulfite solids therefrom as an aqueous sludge. The improvement comprises: the aqueous slaked <span class="hlt">lime</span> added to the scrubbing slurry is formed by mixing <span class="hlt">lime</span> and water, with the water containing a calcium sulfur-oxide salt in an amount sufficient to provide between about 0.3 to 5.0 percent by weight of the calcium sulfur-oxide salt based on the <span class="hlt">lime</span>, whereby the average particle size of calcium sulfite solids in the aqueous sludge is increased to provide improved separation of water of the aqueous sludge therefrom.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('//www.loc.gov/pictures/collection/hh/item/al1051.photos.046680p/','SCIGOV-HHH'); return false;" href="//www.loc.gov/pictures/collection/hh/item/al1051.photos.046680p/"><span>63. INTERIOR VIEW OF THE <span class="hlt">LIME</span> KILN BUILDING, LOOKING AT ...</span></a></p> <p><a target="_blank" href="http://www.loc.gov/pictures/collection/hh/">Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey</a></p> <p></p> <p></p> <p>63. INTERIOR VIEW OF THE <span class="hlt">LIME</span> KILN BUILDING, LOOKING AT THE FIRE BOX AND KILN FOR DILLUTANT. APRIL 22, 1919. - United States Nitrate Plant No. 2, Reservation Road, Muscle Shoals, Muscle Shoals, Colbert County, AL</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23673960','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23673960"><span>Investigation of copper sorption by sugar beet processing <span class="hlt">lime</span> waste.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ippolito, J A; Strawn, D G; Scheckel, K G</p> <p>2013-01-01</p> <p>In the western United States, sugar beet processing for sugar recovery generates a <span class="hlt">lime</span>-based waste product (∼250,000 Mg yr) that has little <span class="hlt">liming</span> value in the region's calcareous soils. This area has recently experienced an increase in dairy production, with dairies using copper (Cu)-based hoof baths to prevent hoof diseases. A concern exists regarding soil Cu accumulation because spent hoof baths may be disposed of in waste ponds, with pond waters being used for irrigation. The objective of this preliminary study was to evaluate the ability of <span class="hlt">lime</span> waste to sorb Cu. <span class="hlt">Lime</span> waste was mixed with increasing Cu-containing solutions (up to 100,000 mg Cu kg <span class="hlt">lime</span> waste) at various buffered pH values (pH 6, 7, 8, and 9) and shaken over various time periods (up to 30 d). Copper sorption phenomenon was quantified using sorption maximum fitting, and the sorption mechanism was investigated using X-ray absorption spectroscopy. Results showed that sorption onto <span class="hlt">lime</span> waste increased with decreasing pH and that the maximum Cu sorption of ∼45,000 mg kg occurred at pH 6. X-ray absorption spectroscopy indicated that Cu(OH) was the probable species present, although the precipitate existed as small multinuclear precipitates on the surface of the <span class="hlt">lime</span> waste. Such structures may be precursors for larger surface precipitates that develop over longer incubation times. Findings suggest that sugar beet processing <span class="hlt">lime</span> waste can viably sorb Cu from liquid waste streams, and thus it may have the ability to remove Cu from spent hoof baths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017028','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017028"><span>Time and metamorphic petrology: <span class="hlt">Calcite</span> to aragonite experiments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hacker, B.R.; Kirby, S.H.; Bohlen, S.R.</p> <p>1992-01-01</p> <p>Although the equilibrium phase relations of many mineral systems are generally well established, the rates of transformations, particularly in polycrystalline rocks, are not. The results of experiments on the <span class="hlt">calcite</span> to aragonite transformation in polycrystalline marble are different from those for earlier experiments on powdered and single-crystal <span class="hlt">calcite</span>. The transformation in the polycrystalline samples occurs by different mechanisms, with a different temperature dependence, and at a markedly slower rate. This work demonstrates the importance of kinetic studies on fully dense polycrystalline aggregates for understanding mineralogic phase changes in nature. Extrapolation of these results to geological time scales suggests that transformation of <span class="hlt">calcite</span> to aragonite does not occur in the absence of volatiles at temperatures below 200??C. Kinetic hindrance is likely to extend to higher temperatures in more complex transformations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20026848','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20026848"><span>Chemistry and kinetics of <span class="hlt">calcite</span> dissolution in passive treatment systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rose, A.W.</p> <p>1999-07-01</p> <p>Reaction of <span class="hlt">calcite</span> with AMD is a key remediation process in anoxic limestone drains, (ALD), SAPS, and many wetlands, but predictions of effluent quality are currently based mainly on rules of thumb and prior experience. The PHREEQC computer program can be used to calculate the progress of this and similar reactions, and aid in understanding, design and evaluation of these systems. At pH values less than 5, <span class="hlt">calcite</span> dissolution rates are strongly influenced by transport parameters such as flow velocity. Estimated <span class="hlt">calcite</span> dissolution rates from ALD's and column experiments indicate little change in rate with pH, in contrast to published data for well stirred lab experiments. The dissolution rate is affected by concentration of SO{sub 4}, Fe, Al, Ca, P, and other trace solutes. The optimum contact time and sizing of ALD's will be dependent on these and possibly other parameters. Additional experiments are needed to evaluate these dependencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=334251','PESTICIDES'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=334251"><span>Water Utility <span class="hlt">Lime</span> Sludge Reuse – An Environmental Sorbent ...</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p><span class="hlt">Lime</span> sludge can be used as an environmental sorbent to remove sulfur dioxide (SO2) and acid gases, by the ultra-fine CaCO3 particles, and to sequester mercury and other heavy metals, by the Natural Organic Matter and residual activated carbon. The laboratory experimental set up included a simulated flue gas preparation unit, a lab-scale wet scrubber, and a mercury analyzer system. The influent mercury concentration was based on a range from 22 surveyed power plants. The reactivity of the <span class="hlt">lime</span> sludge sample for acid neutralization was determined using a method similar to method ASTM C1318-95. Similar experiments were conducted using reagent calcium carbonate and calcium sulfate to obtain baseline data for comparing with the <span class="hlt">lime</span> sludge test results. The project also evaluated the techno-economic feasibility and sustainable benefits of reusing <span class="hlt">lime</span> softening sludge. If implemented on a large scale, this transformative approach for recycling waste materials from water treatment utilities at power generation utilities for environmental cleanup can save both water and power utilities millions of dollars. Huge amounts of <span class="hlt">lime</span> sludge waste, generated from hundreds of water treatment utilities across the U.S., is currently disposed in landfills. This project evaluated a sustainable and economically-attractive approach to the use of <span class="hlt">lime</span> sludge waste as a valuable resource for power generation utilities.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817255R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817255R"><span>Small scale shear zone in <span class="hlt">calcite</span>: AMS and microstructure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roxerová, Zuzana; Machek, Matěj; Kusbach, Vladimír; Racek, Martin; Silva, Pedro F.</p> <p>2016-04-01</p> <p>Two structural profiles across thin shear zone in <span class="hlt">calcite</span> from quarry in Estremoz (Portugal) were studied to find a relationship between AMS and strain in natural rocks. The mesoscopic fabric is characterized by the change from the subhorizontal coarse-grained foliation towards the ~2cm-wide shear zone center with subvertical fine-grained foliation. In microstructure, the shear zone records dynamic recrystallization of <span class="hlt">calcite</span> aggregate which resulted in development of porphyroclastic microstructure with increasing proportion of fine-grained recrystallized matrix towards the shear zone center. Two distinct crystallographic preferred orientations of <span class="hlt">calcite</span> were recorded. One related with porphyroclasts, characterized by subvertical orientation of <span class="hlt">calcite</span> <c> axes and another associated with recrystallized matrix showing subhorizontal <span class="hlt">calcite</span> <c> axes orientation. The magnetic susceptibility ranges from -8e-6SI to 9e-6SI, with the average -4e-6SI. The majority of the rock mass is diamagnetic, corresponding well with the thermomagnetic curves, with local paramagnetic accumulations in form of thin bands. The AMS of the both profiles exhibits stable subvertical foliation bearing vertical lineation which is locally alternated by the medium-angle foliation. We interpret the AMS fabric pattern which is perpendicular to the mineral one as a type of inverse AMS fabric, due to high iron content in major part of <span class="hlt">calcite</span> grains The magnetic and microstructural description of the shear zone is accompanied by numerical modeling of AMS based on CPO and different proportion of porphyroclasts, matrix and mica for purposes of deciphering the influence of present microstructural features on AMS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H21A1051S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H21A1051S"><span>Microbially Induced <span class="hlt">Calcite</span> Precipitation for Subsurface Immobilization of Contaminants</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, R. W.; Fujita, Y.; Ginn, T. R.; Hubbard, S. S.; Dafflon, B.; Delwiche, M.; Gebrehiwet, T.; Henriksen, J. R.; Peterson, J.; Taylor, J. L.</p> <p>2011-12-01</p> <p>Subsurface radionuclide and metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of the greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent trace ions, such as the short-lived radionuclide 90Sr, is co-precipitation in <span class="hlt">calcite</span>. We have found that <span class="hlt">calcite</span> precipitation and co-precipitation of Sr can be accelerated by the activity of urea hydrolyzing microorganisms, that higher <span class="hlt">calcite</span> precipitation rates can result in increased Sr partitioning, and that nutrient additions can stimulate ureolytic activity. To extend our understanding of microbially induced <span class="hlt">calcite</span> precipitation (MICP) in an aquifer setting a continuous recirculation field experiment evaluating MICP was conducted at the Integrated Field Research Challenge (IFRC) site located at Rifle, CO. In this experiment, groundwater extracted from an onsite well was amended with urea (total mass of 42.5 kg) and molasses (a carbon and electron donor) and re-injected into a well approximately 4 meters up-gradient for a period of 12 days followed by 10 months of groundwater sampling and monitoring. Crosshole radar and electrical tomographic data were collected prior, during, and after the MICP treatment. The urea and molasses treatment resulted in an enhanced population of sediment associated urea hydrolyzing organisms as evidenced by increases in the number of ureC gene copies, increases in 14C urea hydrolysis rates, and long-term observations of ammonium (a urea hydrolysis product) in the injection, extraction and down gradient monitoring wells. Permeability changes and increases in the <span class="hlt">calcite</span> saturation indexes in the well field suggest that mineral precipitation has occurred; ongoing analysis of field samples seeks to confirm this. Changes in dielectric constant and electrical conductivity were used to interpret the spatiotemporal distribution of the injectate and subsequent <span class="hlt">calcite</span> precipitation. Modeling activities are underway to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.176..198A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.176..198A"><span>Is bicarbonate stable in and on the <span class="hlt">calcite</span> surface?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Andersson, M. P.; Rodriguez-Blanco, J. D.; Stipp, S. L. S.</p> <p>2016-03-01</p> <p>We have used density functional theory with the COSMO-RS implicit solvent model to predict the pKa for the deprotonation of bicarbonate to carbonate, i.e. HCO3- <=> CO32- + H+, when HCO3- is included in, and adsorbed on, a <span class="hlt">calcite</span> surface. We have used cluster models (80-100 atoms) to represent the flat {10.4} surface, acute steps, obtuse steps, two types of kinks on the acute step and two types of kinks on the obtuse steps. Based on the predicted pKa values, which range from -6.0 to 2.4 depending on the surface site, we conclude that bicarbonate deprotonates to carbonate when it is in <span class="hlt">calcite</span> even when pH in solution is very low. This is true for all surface sites, even for solutions where 2.4 < pH < 6.35, where H2CO30 is the dominant dissolved species. When bicarbonate is adsorbed on <span class="hlt">calcite</span>, the predicted pKa for deprotonation is 7.5, which is ∼3 pH units lower than in aqueous solution, 10.35. This means that adsorbed carbonate is stable even when the concentration of dissolved CO32- is several orders of magnitude lower. This has a significant effect on surface charge and thus the behaviour of the <span class="hlt">calcite</span> surface. Our results help explain the potential determining behaviour of the carbonate species in <span class="hlt">calcite</span>-water systems, particularly in the pH range where the bicarbonate species dominates in water and where the carbonate species dominates at the surface, i.e. when 7.5 < pH < 10.35. Our atomic scale data for the various <span class="hlt">calcite</span> surface sites provide the needed input to improve and constrain surface complexation modelling and are especially useful for predicting behaviour in systems where experiments are difficult or impossible, such as at high temperature and pressure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Geo....23..535D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Geo....23..535D"><span>Paleozoic Mg <span class="hlt">calcite</span> preserved: Implications for the Carboniferous ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dickson, J. A. D.</p> <p>1995-06-01</p> <p>Modern Mg <span class="hlt">calcite</span> echinoderm skeletons are thought to lose Mg so rapidly that no pre-Pleistocene ossicles retain their original Mg concentrations; however, Carboniferous echinoderm skeletons from the Imo Formation of Arkansas and the Holder Formation of New Mexico are reported herein that are still composed of Mg <span class="hlt">calcite</span> (7.8 to 14.5 mol% MgCO3). Their Sr concentration is also high (620 to 3710 ppm). The pore system in these echinoderm skeletons is filled with ferroan <span class="hlt">calcite</span> or siderite that has not grown in optical continuity with the skeleton. The discovery of Carboniferous Mg <span class="hlt">calcite</span> confirms an interpretation already made from their diagenetic replacements. Marine Mg <span class="hlt">calcite</span> has been associated with proposed icehouse conditions, and although the Carboniferous echinoderm skeletons are compatible with this as they formed during Gondwana glaciation, they are too few to be of significance. Also they are organic secretions and so can override secular mineral trends based on inorganic precipitates. The Carboniferous echinoderm skeletons, produced in tropical waters, have a concentration of Mg similar to values for modern echinoderms. The simplest explanation for this similarity is that both precipitated by similar processes from oceans of similar composition. This does not support predictions, based on mass-balance modeling, that the Mg/Ca ratio of the Carboniferous ocean was half that of today's. The Sr content of Carboniferous echinoderms is less than that for modern echinoderms, leading to a prediction of 6 ppm Sr concentration for the Carboniferous ocean. Further examples of Mg <span class="hlt">calcite</span> are required to substantiate these interpretations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5880302','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5880302"><span>Radiaxial-fibrous <span class="hlt">calcites</span> of shallow subsurface diagenetic origin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mazzullo, S.J.; Bischoff, W.D.; Lobitzer, H.</p> <p>1989-03-01</p> <p>Radiaxial-fibrous <span class="hlt">calcites</span> (RFC) in marine carbonates are generally considered syndepositional cements. In Upper Triassic and basal Liassic reef and platform limestones in Austria (Steinplatte complex), however, isopachous RFC is demonstrably a postdepositional diagenetic component that precipitated in shallow-burial phreatic environments during a time of periodic meteoric exposure. Isopachous RFC occurs solely within solution cavities and is interlayered with internal red sediment; discontinuities due to leaching separate sequential generations of RFC in the rocks. Accordingly, one possibility is that the RFC was originally low-magnesium <span class="hlt">calcite</span> that precipitated in the meteoric phreatic zone during lowstands. Such <span class="hlt">calcites</span> contain relatively low magnesium concentrations (average 0.87 mole % MgCO/sub 3/) and are /sup 18/O depleted (average - 5.81 /per thousand/ PDB). However, most other RFC cements in the sequence average slightly higher magnesium comparable to crinoidal <span class="hlt">calcites</span> (1.13 mole % MgCO/sub 3/), are less depleted in /sup 18/O (average - 1.88 /per thousand/ PDB), and are partly dolomitized. Additionally, all the RFC cements are enriched in /sup 13/C to values similar to that of Triassic and Jurassic seawater (+ 2.86 /per thousand/ PDB) and are nonluminescent. Trace element studies indicate alteration of the rocks in partly closed, rock-dominated diagenetic systems. By these facts, the authors favor a precursor high-magnesium <span class="hlt">calcite</span> mineralogy for the RFC cements, which possibly precipitated during highstands when meteoric pore waters were replaced by marine fluids. Thus, the geochemical trends observed are likely due to variations in the degree of meteoric alteration of high-magnesium <span class="hlt">calcite</span> RFC rather than to differences in original mineralogy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70023750','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70023750"><span>Global occurrences of gas <span class="hlt">hydrate</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kvenvolden, K.A.; Lorenson, T.D.</p> <p>2001-01-01</p> <p>Natural gas <span class="hlt">hydrate</span> is found worldwide in sediments of outer continental margins of all oceans and in polar areas with continuous permafrost. There are currently 77 localities identified globally where geophysical, geochemical and/or geological evidence indicates the presence of gas <span class="hlt">hydrate</span>. Details concerning individual gas-<span class="hlt">hydrate</span> occurrences are compiled at a new world-wide-web (www) site (http://walrus.wr.usgs.gov/globalhydrate). This site has been created to facilitate global gas-<span class="hlt">hydrate</span> research by providing information on each of the localities where there is evidence for gas <span class="hlt">hydrate</span>. Also considered are the implications of gas <span class="hlt">hydrate</span> as a potential (1) energy resource, (2) factor in global climate change, and (3) geohazard.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1082747','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1082747"><span>Rapid gas <span class="hlt">hydrate</span> formation process</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.</p> <p>2013-01-15</p> <p>The disclosure provides a method and apparatus for forming gas <span class="hlt">hydrates</span> from a two-phase mixture of water and a <span class="hlt">hydrate</span> forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas <span class="hlt">hydrate</span>. The reaction zone pressure is less than the mixing zone pressure so that expansion of the <span class="hlt">hydrate</span>-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the <span class="hlt">hydrate</span>-forming gas. The result of the process is the formation of gas <span class="hlt">hydrates</span> continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.4788M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.4788M"><span>Magnesium incorporation in <span class="hlt">calcite</span> in the presence of organic ligands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mavromatis, Vasileios; Baldermann, Andre; Purgstaller, Bettina; Dietzel, Martin</p> <p>2015-04-01</p> <p>The formation of authigenic Mg-<span class="hlt">calcites</span> in marine early diagenetic environments is commonly driven by a bio-induced process, the anaerobic oxidation of methane (AOM), which provides inorganic carbon required for the precipitation of such authigenic carbonates. In such settings the availability of major and/or trace divalent metal cations (Me2+) incorporated in <span class="hlt">calcite</span> and their aqueous speciation are controlled by the presence of aqueous organic molecules that are produced either as (by-)products of biological activity (i.e. exopolymeric substances) or during degradation of allochthonous organic matter in the sediments. Despite the fact that the presence of aqueous organic ligands strongly affects the growth rates and the mineralogy of precipitating CaCO3 polymorphs, till now no study addresses the role of Me2+-ligand aqueous complexes on the extent of Mg and/or other trace element content of Mg-<span class="hlt">calcites</span>. In order to shed light on this process, relevant to authigenic <span class="hlt">calcite</span> formation in organic-rich marine sediments and continental soils, we precipitated <span class="hlt">calcite</span> in the presence of aqueous Mg and a variety of low molecular weight carboxylic- and aminoacids. Our experimental data indicate that the presence of organic ligands augments significantly the saturation state of <span class="hlt">calcite</span> in the parent fluid during its precipitation. Moreover, they suggest that the higher the ligand concentration, the higher the obtained distribution coefficient of Mg in <span class="hlt">calcite</span>. The latter is directly proportional to the ratio of Mg2+/Ca2+ aqueous ions for all ligands used. Hydrogeochemical modelling of the aqueous fluids indicate that the observed correlation can be explained by the stronger complexation of Ca2+ with organic ligands compared to Mg2+, which results in higher availability of Mg2+ vs. Ca2+ aqueous ions. Overall the obtained results suggest that the higher the organic ligand aqueous concentration the higher the Mg content of <span class="hlt">calcite</span> forming from this fluid. These findings are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B12C0787D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B12C0787D"><span>Sulfated Macromolecules as Templates for <span class="hlt">Calcite</span> Nucleation and Growth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>David, M.; Passalacqua, K.; Neira, A. C.; Fernandez, M. S.</p> <p>2003-12-01</p> <p>Mineralization of egg and seashells is controlled by an intimate association of inorganic materials with organic macromolecules. Among them, particular polyanionic sulfated macromolecules referred to as proteoglycans have been described to be involved in the calcification of these biominerals. The sulfated moieties of the proteoglycans are part of polymer chains constituted of building-blocks of disaccharide units, referred to as sulfated glycosaminoglycans (GAGs), which are covalently attached to a protein core. By using a sitting drop crystallization assay under controlled conditions of time, pH and reactants concentration, we have tested several sulfated and non-sulfated GAGs (i.e.: dermatan and keratan sulfate, hyaluronic acid and heparin), differing in their sulfonate and carboxylate degree and pattern, in their ability to modify calcium carbonate crystal morphology as observed under scanning electron microscopy. Without the addition of GAGs, regular \\{104\\} rhombohedral <span class="hlt">calcite</span> crystals were obtained. When hyaluronic acid (HA), a non-sulfated but carboxylated GAG, was added, 20 mm long piles of unmodified <span class="hlt">calcite</span> crystals were observed. When desulfated dermatan, which is an epimeric form of HA but shorter polymer, having their carboxylate groups in an inverted configuration, was added, isolated rhombohedral \\{104\\} <span class="hlt">calcite</span> crystals showing rounded corners with planes oriented parallel to the c axis were observed. When dermatan sulfated was added, isolated <span class="hlt">calcite</span> crystals exhibit a columnar morphology as a \\{hk0\\} cylinder with three \\{104\\} faces forming a cap at both ends. Heparin activity depends on the fraction added. Fast-moving heparin fraction (FM), is an undersulfated, low-molecular-weight heterogeneous polymer, while slow-moving heparin fraction (SM) is an high-molecular-weight homogeneous polymer rich in trisulfated-disaccharide units. When FM was added, isolated <span class="hlt">calcite</span> crystals displayed rhombohedrical \\{104\\} faces but flat corners of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5697078','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/5697078"><span>Gas <span class="hlt">hydrate</span> cool storage system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ternes, M.P.; Kedl, R.J.</p> <p>1984-09-12</p> <p>The invention presented relates to the development of a process utilizing a gas <span class="hlt">hydrate</span> as a cool storage medium for alleviating electric load demands during peak usage periods. Several objectives of the invention are mentioned concerning the formation of the gas <span class="hlt">hydrate</span> as storage material in a thermal energy storage system within a heat pump cycle system. The gas <span class="hlt">hydrate</span> was formed using a refrigerant in water and an example with R-12 refrigerant is included. (BCS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25403973','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25403973"><span>Anthropogenic oligotrophication via <span class="hlt">liming</span>: Long-term phosphorus trends in acidified, <span class="hlt">limed</span>, and neutral reference lakes in Sweden.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Qian; Huser, Brian J</p> <p>2014-01-01</p> <p>Restoration of acidified lakes by <span class="hlt">liming</span> does not, in many cases, improve productivity to a pre-acidified state. We hypothesize that the poor recovery detected in many of these lakes is due to constrained in-lake phosphorous (P) cycling caused by enhanced precipitation of metals in higher pH, <span class="hlt">limed</span> waters. Long-term (1990-2012) data for 65 <span class="hlt">limed</span>, circum-neutral (pH 6-8), and acidified lakes in Sweden were analyzed to determine trends for P and potential drivers of these trends. <span class="hlt">Limed</span> lakes not only had lower mean values and stronger decreasing trends for total P than non-<span class="hlt">limed</span> lakes, but they also had the highest percentage of decreasing trends (85 %). A P release factor (Hypolimnetic P/Epilimnetic P) was developed to elucidate differences in internal P cycling between lake groups. Consistently, lower P release factors in <span class="hlt">limed</span> lakes show limitation of internal P cycling during summer months that may be a factor limiting P bioavailability and thus productivity of these systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6455015','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6455015"><span>Evaluation of hazardous waste incineration in a <span class="hlt">lime</span> kiln: Rockwell <span class="hlt">Lime</span> Company. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Day, D.R.; Cox, L.A.</p> <p>1984-08-01</p> <p>During a one-week test burn, hazardous waste was used as supplemental fuel and co-fired with petroleum coke in a <span class="hlt">lime</span> kiln in eastern Wisconsin. Detailed sampling and analysis was conducted on the stack gas for principal organic hazardous constituents (POHCs), particulates, particulate metals, HCl, SO2, NOx, CO, and THC and on process streams for metals and chlorine. POHCs were also analyzed in the waste fuel. Sampling was conducted during three baseline and five waste fuel test burn days. The program objectives were to determine the destruction and removal efficiency (DRE) for each POHC, determine concentration of stack gas pollutants under baseline and waste fuel test burn conditions, determine the fate of chlorine, sulfur, and trace metals in the kiln process, and evaluate kiln performance when operating with hazardous waste as supplemental fuel. Results show average DRE's greater than 99.99 percent for each POHC and little change in pollutant emissions from baseline to waste fuel test conditions. In addition, material balance results show that 95 percent of chlorine enters the process from the limestone feed and the chlorine exits the kiln in the baghouse dust and <span class="hlt">lime</span> product at 61 percent and 38 percent, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1188932','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1188932"><span>Anomalous porosity preservation and preferential accumulation of gas <span class="hlt">hydrate</span> in the Andaman accretionary wedge, NGHP-01 site 17A</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rose, Kelly K.; Johnson, Joel E.; Torres, Marta E.; Hong, WeiLi; Giosan, Liviu; Solomon, E.; Kastner, Miriam; Cawthern, Thomas; Long, Philip E.; Schaef, Herbert T.</p> <p>2014-12-01</p> <p>In addition to well established properties that control the presence or absence of the <span class="hlt">hydrate</span> stability zone, such as pressure, temperature, and salinity, additional parameters appear to influence the concentration of gas <span class="hlt">hydrate</span> in host sediments. The stratigraphic record at Site 17A in the Andaman Sea, eastern Indian Ocean, illustrates the need to better understand the role pore-scale phenomena play in the distribution and presence of marine gas <span class="hlt">hydrates</span> in a variety of subsurface settings. In this paper we integrate field-generated datasets with newly acquired sedimentology, physical property, imaging and geochemical data with mineral saturation and ion activity products of key mineral phases such as amorphous silica and <span class="hlt">calcite</span>, to document the presence and nature of secondary precipitates that contributed to anomalous porosity preservation at Site 17A in the Andaman Sea. This study demonstrates the importance of grain-scale subsurface heterogeneities in controlling the occurrence and distribution of concentrated gas <span class="hlt">hydrate</span> accumulations in marine sediments, and document the importance that increased permeability and enhanced porosity play in supporting gas concentrations sufficient to support gas <span class="hlt">hydrate</span> formation. The grain scale relationships between porosity, permeability, and gas <span class="hlt">hydrate</span> saturation documented at Site 17A likely offer insights into what may control the occurrence and distribution of gas <span class="hlt">hydrate</span> in other sedimentary settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9790N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9790N"><span>Soil pH management without <span class="hlt">lime</span>, a strategy to reduce greenhouse gas emissions from cultivated soils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nadeem, Shahid; Bakken, Lars; Reent Köster, Jan; Tore Mørkved, Pål; Simon, Nina; Dörsch, Peter</p> <p>2015-04-01</p> <p>For decades, agricultural scientists have searched for methods to reduce the climate forcing of food production by increasing carbon sequestration in the soil and reducing the emissions of nitrous oxide (N2O). The outcome of this research is depressingly meagre and the two targets appear incompatible: efforts to increase carbon sequestration appear to enhance the emissions of N2O. Currently there is a need to find alternative management strategies which may effectively reduce both the CO2 and N2O footprints of food production. Soil pH is a master variable in soil productivity and plays an important role in controlling the chemical and biological activity in soil. Recent investigations of the physiology of denitrification have provided compelling evidence that the emission of N2O declines with increasing pH within the range 5-7. Thus, by managing the soil pH at a near neutral level appears to be a feasible way to reduce N2O emissions. Such pH management has been a target in conventional agriculture for a long time, since a near-neutral pH is optimal for a majority of cultivated plants. The traditional way to counteract acidification of agricultural soils is to apply <span class="hlt">lime</span>, which inevitably leads to emission of CO2. An alternative way to increase the soil pH is the use of mafic rock powders, which have been shown to counteract soil acidification, albeit with a slower reaction than <span class="hlt">lime</span>. Here we report a newly established field trail in Norway, in which we compare the effects of <span class="hlt">lime</span> and different mafic mineral and rock powders (olivine, different types of plagioclase) on CO2 and N2O emissions under natural agricultural conditions. Soil pH is measured on a monthly basis from all treatment plots. Greenhouse gas (GHG) emission measurements are carried out on a weekly basis using static chambers and an autonomous robot using fast box technique. Field results from the first winter (fallow) show immediate effect of <span class="hlt">lime</span> on soil pH, and slower effects of the mafic rocks. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6047B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6047B"><span>Aragonite / <span class="hlt">Calcite</span> seas and the evolution of biomineralization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balthasar, Uwe</p> <p>2015-04-01</p> <p>The vast majority of marine invertebrate skeletons are composed of the CaCO3 polymorphs aragonite and <span class="hlt">calcite</span>, yet the influence of seawater composition on the evolution of calcareous skeletal composition is poorly understood. The main theoretical framework in which the evolution of CaCO3 shell mineralogy is assessed is the aragonite-<span class="hlt">calcite</span> sea hypothesis with conventional thinking suggesting that a threshold in the marine Mg:Ca ratio determines CaCO3 polymorph formation. I present data from CaCO3 precipitation experiments to show that the concept of a distinct threshold is misleading because Mg:Ca ratio and temperature combined result in a Phanerozoic continuum of co-existing aragonite-<span class="hlt">calcite</span> seas with aragonite-facilitating conditions existing throughout the Phanerozoic in shallow warm-water (>20° C) environments. The stable reservoir of aragonite-favouring conditions in shallow warm water environments potentially explains the trend of increasing occurrences of skeletal aragonite throughout the Phanerozoic, particularly in the context of the 'out of the tropics' hypothesis. By contrast, the most prominent fluctuations with respect to aragonite-<span class="hlt">calcite</span> sea conditions can be expected to have occurred in mid- to high latitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050000477&hterms=Amphibians&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAmphibians','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050000477&hterms=Amphibians&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DAmphibians"><span>Utricular otoconia of some amphibians have <span class="hlt">calcitic</span> morphology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pote, K. G.; Ross, M. D.</p> <p>1993-01-01</p> <p>This report concerns the morphological features of otoconia removed from the inner ear of four amphibian species. Results from scanning electron microscopic examination are compared based on the site of origin. These results show that utricular otoconia have a mineral structure that mimics <span class="hlt">calcite</span>, rather than the widely accepted idea that they are mineralized by calcium carbonate of the aragonite polymorph.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/289451','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/289451"><span>Atomistic simulation of the differences between <span class="hlt">calcite</span> and dolomite surfaces</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Titiloye, J.O.; Leeuw, N.H. de; Parker, S.C.</p> <p>1998-08-01</p> <p>Atomistic simulation methods have been used to calculate and compare the surface structures and energies of the {l_brace}10{bar 1}4{r_brace}, {l_brace}0001{r_brace}, {l_brace}10{bar 1}0{r_brace}, {l_brace}11{bar 2}0{r_brace} and {l_brace}10{bar 1}1{r_brace} surfaces of <span class="hlt">calcite</span> and dolomite and to evaluate their equilibrium morphologies. The <span class="hlt">calcite</span> {l_brace}10{bar 1}4{r_brace} and the dolomite {l_brace}10{bar 1}0{r_brace} and {l_brace}11{bar 2}0{r_brace} surfaces are the most stable crystal planes. Investigation of the segregation of Mg and Ca ions in the dolomite crystal shows a clear preference for Ca{sup 2+} ions at the surface sites and for Mg{sup 2+} ions in the bulk sites and hence growth onto dolomite results in calcium carbonate or high magnesian <span class="hlt">calcite</span> crystals which helps explain the difficulty in crystallizing dolomite vs. <span class="hlt">calcite</span> under laboratory conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20449036','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20449036"><span>Proton/calcium ion exchange behavior of <span class="hlt">calcite</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Villegas-Jiménez, Adrián; Mucci, Alfonso; Paquette, Jeanne</p> <p>2009-10-21</p> <p>The characterization of the proton sorptive properties of <span class="hlt">calcite</span> in aqueous solutions at 25 +/- 1 degrees C over a relatively wide range of chemical conditions (7.16 <or= pH <or= 9.7; 3 x 10(-5) M <or=SigmaCa <or= 5 x 10(-3) M; 10(-4) M <or=SigmaCO(2)<or= 1.7 x 10(-3) M) and solid : solution ratios (0.4 to 12.3 g L(-1)) was performed using a novel surface titration technique. A large net proton uptake, coupled with a significant release of Ca(2+) ions is consistently observed, greatly exceeding the theoretical number of reactive surface sites. These observations are interpreted as a fast proton/calcium exchange equilibrium between the solution and "exchangeable cation sites" (e.g., lattice positions) at and/or beneath the <span class="hlt">calcite</span> surface (species identified by "(exc)"), , that leads to a transient, "apparent" incongruent dissolution regime and the formation of a stable calcium-deficient, proton-enriched layer within the <span class="hlt">calcite</span> lattice under circum-neutral and alkaline regimes at standard conditions. The 2H(+)/Ca(2+) ion exchange is quantitatively described by the Langmuir-power exchange function under the Vanselow convention: where n = 1 and log(10)K(ex) = 13.0 +/- 0.3. This <span class="hlt">calcite</span> behavior, never reported before, masks surface equilibria and directly impacts the aqueous speciation of carbonate-rock systems with poor CO(2)(g) ventilation (e.g., aquifers, pore and deep sea waters, industrial reactors) via the buffering of pH and <span class="hlt">calcite</span> dissolution. In contrast, at fixed pCO(2) conditions, aqueous speciation remains unaffected upon CO(2)(g) sequestration resulting from ion exchange-induced <span class="hlt">calcite</span> precipitation: ([triple bond]CaCO3)2(exc) + CO2(g) + H2O <==> [triple bond]Ca(HCO3)2(exc) + CaCO3(s). Accordingly, reliable predictions of aqueous speciation in natural or engineered <span class="hlt">calcite</span>-containing systems at variable pCO(2) conditions must consider this exchange reaction and the associated K(ex). The postulated proton/calcium exchange may have far</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.183...46P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.183...46P"><span>NMR spectroscopic study of organic phosphate esters coprecipitated with <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Phillips, Brian L.; Zhang, Zelong; Kubista, Laura; Frisia, Silvia; Borsato, Andrea</p> <p>2016-06-01</p> <p>Organic phosphorus incorporated in <span class="hlt">calcite</span> during laboratory precipitation experiments and in natural cave deposits was investigated by solid-state NMR spectroscopy. For <span class="hlt">calcite</span> precipitated in the presence of organic phosphoesters of varying size and functionality, solid-state 31P{1H} CP/MAS NMR shows that the phosphoesters were incorporated intact into the solid. Systematic changes in the 31P NMR chemical shift of the phosphate group were observed between the solid phosphoester and that incorporated in the solid precipitate, yielding 31P NMR chemical shifts of the coprecipitates in the range of +1.8 to -2.2 ppm. These chemical shifts are distinct from that of similarly prepared <span class="hlt">calcite</span> coprecipitated with inorganic phosphate, 3.5 ppm. Only minor changes were noted in the phosphoester 31P chemical shift anisotropy (CSA) which suggests no significant change in the local structure of the phosphate group, which is dominated by C-O-P bonding. Close spatial proximity of the organic phosphate group to <span class="hlt">calcite</span> structural components was revealed by 31P/13C rotational echo double resonance (REDOR) experiments for coprecipitates prepared with 13C-labeled carbonate. All coprecipitates showed significant 31P dephasing effects upon 13C-irradiation, signaling atomic-scale proximity to carbonate carbon. The dephasing rate for smaller organophosphate molecules is similar to that observed for inorganic phosphate, whereas much slower dephasing was observed for larger molecules having long and/or bulky side-chains. This result suggests that small organic molecules can be tightly enclosed within the <span class="hlt">calcite</span> structure, whereas significant structural disruption required to accommodate the larger organic molecules leads to longer phosphate-carbonate distances. Comparison of 31P NMR spectroscopic data from the synthetic coprecipitates with those from <span class="hlt">calcite</span> moonmilk speleothems indicates that phosphorus occurs mainly as inorganic orthophosphate in the natural deposits, although small</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001GeCoA..65.4131H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001GeCoA..65.4131H"><span>The behavior of Ni 2+ on <span class="hlt">calcite</span> surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hoffmann, U.; Stipp, S. L. S.</p> <p>2001-11-01</p> <p>Transport of Ni 2+ in the geosphere plays a role in the formation of ore deposits as well as in the dispersion of contaminants in the environment. Some elements (Cd 2+, Zn 2+, Na +, K +, and Cl -) are known to diffuse in <span class="hlt">calcite</span> at the rate of nanometers in months, so questions arose about the ability of Ni 2+ to move away from adsorption sites at the surface into the bulk. Nickel incorporation into <span class="hlt">calcite</span> is limited by its high dehydration enthalpy and by its ligand field hindrance to entering the distorted octahedra of <span class="hlt">calcite</span>, but evidence exists that <span class="hlt">calcite</span> can tolerate several percent Ni 2+ in the structure. Cleaved samples of Iceland spar were exposed for 1 minute to solutions of 10 -3 M and 10 -2 M Ni(ClO 4) 2, the solution was physically removed and the samples were examined using the surface sensitive techniques: X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and Atomic Force Microscopy (AFM). XPS and TOF-SIMS showed that Ni 2+ was adsorbed while AFM confirmed that dissolution was taking place. The sample was stored in air and relative surface concentration and physical morphology were monitored for 2 years. Trends in the chemical data suggested statistically significant loss of surface Ni 2+ with time, but the decrease was very close to the limits for significance. AFM images demonstrated that surface topography of the Ni-exposed samples is modified by spontaneous recrystalization in the water layer adsorbed from air in exactly the same way that clean <span class="hlt">calcite</span> surfaces typically rearrange. This process could bury a small amount of Ni 2+ in the bulk, explaining the very weak loss. Limited burial of Ni 2+ within the near-surface could renew <span class="hlt">calcite</span> adsorption sites, thus increasing uptake capacity. Evidence indicates that surface recrystalization occurs even in very dry environments (<5% humidity). This means that burial could play a role in Ni 2+ mobility in unsaturated groundwater regimes or in fractures</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026209','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026209"><span>Ductile flow of methane <span class="hlt">hydrate</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Durham, W.B.; Stern, L.A.; Kirby, S.H.</p> <p>2003-01-01</p> <p>Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane <span class="hlt">hydrate</span> over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas <span class="hlt">hydrate</span> properties, is impressive: over the thermal range where both are solid, methane <span class="hlt">hydrate</span> is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane <span class="hlt">hydrate</span> in sediments to environmental changes is expected to be dependent on the distribution of the <span class="hlt">hydrate</span> phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If <span class="hlt">hydrate</span> is in the former mode, the very high strength of methane <span class="hlt">hydrate</span> implies a significantly greater strain-energy release upon decomposition and subsequent failure of <span class="hlt">hydrate</span>-cemented formations than previously expected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22415955','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22415955"><span>Some thermodynamical aspects of protein <span class="hlt">hydration</span> water</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Sebastiano; Vasi, Cirino; Stanley, H. Eugene; Chen, Sow-Hsin</p> <p>2015-06-07</p> <p>We study by means of nuclear magnetic resonance the self-diffusion of protein <span class="hlt">hydration</span> water at different <span class="hlt">hydration</span> levels across a large temperature range that includes the deeply supercooled regime. Starting with a single <span class="hlt">hydration</span> shell (h = 0.3), we consider different <span class="hlt">hydrations</span> up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein <span class="hlt">hydration</span> water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the <span class="hlt">hydration</span> level and (ii) the first <span class="hlt">hydration</span> shell remains liquid at all <span class="hlt">hydrations</span>, even at the lowest temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27722052','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27722052"><span>Experimental investigation and constitutive model for <span class="hlt">lime</span> mudstone.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Junbao; Liu, Xinrong; Zhao, Baoyun; Song, Zhanping; Lai, Jinxing</p> <p>2016-01-01</p> <p>In order to investigate the mechanical properties of <span class="hlt">lime</span> mudstone, conventional triaxial compression tests under different confining pressures (0, 5, 15 and 20 MPa) are performed on <span class="hlt">lime</span> mudstone samples. The test results show that, from the overall perspective of variation law, the axial peak stress, axial peak strain and elastic modulus of <span class="hlt">lime</span> mudstone tend to gradually increase with increasing confining pressure. In the range of tested confining pressure, the variations in axial peak stress and elastic modulus with confining pressure can be described with linear functions; while the variation in axial peak strain with confining pressure can be reflected with a power function. To describe the axial stress-strain behavior in failure process of <span class="hlt">lime</span> mudstone, a new constitutive model is proposed, with the model characteristics analyzed and the parameter determination method put forward. Compared with Wang' model, only one parameter n is added to the new model. The comparison of predicted curves from the model and test data indicates that the new model can preferably simulate the strain softening property of <span class="hlt">lime</span> mudstone and the axial stress-strain response in rock failure process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AtmEn..42.5672H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AtmEn..42.5672H"><span>Water adsorption and cloud condensation nuclei activity of <span class="hlt">calcite</span> and <span class="hlt">calcite</span> coated with model humic and fulvic acids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hatch, Courtney D.; Gierlus, Kelly M.; Schuttlefield, Jennifer D.; Grassian, Vicki H.</p> <p></p> <p>Recent studies have shown that organics can alter the water adsorption and cloud condensation nuclei (CCN) activity of common deliquescent species in the Earth's atmosphere. However, very little is known about the effect of organics on water adsorption and CCN activity of insoluble nuclei, such as mineral dust aerosol. A large fraction of unidentified organic material in aerosol particles is composed of poly-acidic compounds resembling humic substances. The presence of these humic-like substances (HULIS) can alter the water adsorption and CCN activity of mineral dust aerosol. We have measured the CCN activity of model humic and fulvic acids and of mineral dust particles coated with these substances in the laboratory. We find that coatings of humic and fulvic acids on <span class="hlt">calcite</span> particles significantly increases water adsorption compared to uncoated particles. CCN measurements indicate that humic- or fulvic acid-coated <span class="hlt">calcite</span> particles are more CCN active than uncoated <span class="hlt">calcite</span> particles. Additionally, thicker coatings of humic or fulvic acids appear to result in more efficient CCN activity. Thus, mineral dust particles coated with high molecular weight organic materials will take up more water and become more efficient CCN in the atmosphere than uncoated mineral dust particles, potentially altering the effect of mineral dust on the Earth's climate. In addition to the experimental results, we have explored a newly modified Köhler theory for predicting the CCN activity of insoluble, wettable particles based on multi layer water adsorption measurements of <span class="hlt">calcite</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeCoA.144..126L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeCoA.144..126L"><span>Aragonite, breunnerite, <span class="hlt">calcite</span> and dolomite in the CM carbonaceous chondrites: High fidelity recorders of progressive parent body aqueous alteration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Martin R.; Lindgren, Paula; Sofe, Mahmood R.</p> <p>2014-11-01</p> <p>Carbonate minerals in CM carbonaceous chondrite meteorites, along with the silicates and sulphides with which they are intergrown, provide a detailed record of the nature and evolution of parent body porosity and permeability, and the chemical composition, temperature and longevity of aqueous solutions. Fourteen meteorites were studied that range in petrologic subtype from mildly aqueously altered CM2.5 to completely <span class="hlt">hydrated</span> CM2.0. All of them contain <span class="hlt">calcite</span>, whereas aragonite occurs only in the CM2.5-CM2.2 meteorites and dolomite in the CM2.2-CM2.0. All of the aragonite crystals, and most of the <span class="hlt">calcite</span> and dolomite grains, formed during early stages of parent body aqueous alteration by cementation of pores produced by the melting of tens of micrometre size particles of H2O-rich ice. Aragonite was the first carbonate to precipitate in the CM2.5 to CM2.2 meteorites, and grew from magnesium-rich solutions. In the least altered of these meteorites the aragonite crystals formed in clusters owing to physical restriction of aqueous fluids within the low permeability matrix. The strong correlation between the petrologic subtype of a meteorite, the abundance of its aragonite crystals and the proportion of them that have preserved crystal faces, is because aragonite was dissolved in the more altered meteorites on account of their higher permeability, and/or greater longevity of the aqueous solutions. Dolomite and breunnerite formed instead of aragonite in some of the CM2.1 and CM2.2 meteorites owing to higher parent body temperatures. The pore spaces that remained after precipitation of aragonite, dolomite and breunnerite cements were occluded by <span class="hlt">calcite</span>. Following completion of cementation, the carbonates were partially replaced by phyllosilicates and sulphides. <span class="hlt">Calcite</span> in the CM2.5-CM2.2 meteorites was replaced by Fe-rich serpentine and tochilinite, followed by Mg-rich serpentine. In the CM2.1 and CM2.0 meteorites dolomite, breunnerite and <span class="hlt">calcite</span> were replaced by Fe</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmEn.146..245H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmEn.146..245H"><span>Long term trends of fish after <span class="hlt">liming</span> of Swedish streams and lakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holmgren, Kerstin; Degerman, Erik; Petersson, Erik; Bergquist, Björn</p> <p>2016-12-01</p> <p>Thousands of Swedish acidified lakes and streams have been regularly <span class="hlt">limed</span> for about 30 years. Standard sampling of fish assemblages in lakes and streams was an important part of monitoring the trends after <span class="hlt">liming</span>, i.e. sampling with multi-mesh gillnets in lakes (EN 14757) and electrofishing in streams (EN 14011). Monitoring data are nationally managed, in the National Register of Survey test-fishing and the Swedish Electrofishing Register. We evaluated long-term data from 1029 electrofishing sites in <span class="hlt">limed</span> streams and gillnet sampling in 750 <span class="hlt">limed</span> lakes, along with reference data from 195 stream sites and 101 lakes with no upstream <span class="hlt">liming</span> in their catchments. The median year of first <span class="hlt">liming</span> was 1986 for both streams and lakes. The proportion of <span class="hlt">limed</span> stream sites with no fish clearly decreased with time, mean species richness and proportion of sites with brown trout (Salmo trutta) recruits increased. There were no consistent trends in fish occurrence or species richness at non-<span class="hlt">limed</span> sites, but occurrence of brown trout recruits also increased in acid as well as neutral reference streams. Abundance of brown trout, perch (Perca fluviatilis) and roach (Rutilus rutilus) increased significantly more at <span class="hlt">limed</span> sites than at non-<span class="hlt">limed</span> reference sites sampled before and after 1986. The mean species richness did not change consistently in <span class="hlt">limed</span> lakes, but decreased in low alkalinity reference lakes, and fish abundance decreased significantly in <span class="hlt">limed</span> as well as in non-<span class="hlt">limed</span> lakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5126405','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5126405"><span>Recovery of aluminum oxide by the Ames <span class="hlt">lime</span>-soda sinter process: scale-up using a rotary kiln</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Murtha, M.J.; Burnet, G.; Harnby, N.</p> <p>1985-01-01</p> <p>The Ames <span class="hlt">Lime</span>-Soda Sinter Process provides a means for recovering aluminum oxide from power plant fly ash while producing a residue that can be used in the manufacture of sulfate resistant (Type V) portland cement. The process has been fully researched and its feasibility is now being demonstrated through pilot plant scale investigation. This paper reports results of the pelletized feed preparation by agglomeration in a rotary pan granulator, continuous feed sintering in an electrically heated rotary kiln, and product recovery from the clinker by aqueous extraction, desilication of the filtrate, and precipitation of a <span class="hlt">hydrated</span> aluminum oxide. Results from earlier bench-scale research have been found to apply consistently to the pilot plant scale work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...710952P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...710952P"><span>Understanding silicate <span class="hlt">hydration</span> from quantitative analyses of <span class="hlt">hydrating</span> tricalcium silicates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; D'Espinose de Lacaillerie, Jean-Baptiste</p> <p>2016-03-01</p> <p>Silicate <span class="hlt">hydration</span> is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement <span class="hlt">hydration</span>. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-<span class="hlt">hydrates</span> (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the <span class="hlt">hydration</span> process in terms of transient local molecular composition, extent of silicate <span class="hlt">hydration</span> and polymerization. This provides insights on the relative influence of surface hydroxylation and <span class="hlt">hydrate</span> precipitation on the <span class="hlt">hydration</span> rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820784','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4820784"><span>Understanding silicate <span class="hlt">hydration</span> from quantitative analyses of <span class="hlt">hydrating</span> tricalcium silicates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; d'Espinose de Lacaillerie, Jean-Baptiste</p> <p>2016-01-01</p> <p>Silicate <span class="hlt">hydration</span> is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement <span class="hlt">hydration</span>. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-<span class="hlt">hydrates</span> (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the <span class="hlt">hydration</span> process in terms of transient local molecular composition, extent of silicate <span class="hlt">hydration</span> and polymerization. This provides insights on the relative influence of surface hydroxylation and <span class="hlt">hydrate</span> precipitation on the <span class="hlt">hydration</span> rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured. PMID:27009966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016BGeo...13.6487K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016BGeo...13.6487K"><span>Carbonate "clumped" isotope signatures in aragonitic scleractinian and <span class="hlt">calcitic</span> gorgonian deep-sea corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kimball, Justine; Eagle, Robert; Dunbar, Robert</p> <p>2016-12-01</p> <p> between the corals of different mineralogy is in the same direction as published theoretical predictions for the offset between <span class="hlt">calcite</span> and aragonite although the magnitude of the offset is different. One possibility is that the deep-sea coral results reflect high-Mg and aragonite crystals attaining nominal mineral equilibrium clumped isotope signatures due to conditions of extremely slow growth. In that case, a possible explanation for the attainment of disequilibrium bulk isotope signatures and equilibrium clumped isotope signatures by deep-sea corals is that extraordinarily slow growth rates can promote the occurrence of isotopic reordering in the interfacial region of growing crystals. We also cannot rule out a component of a biological "vital effect" influencing clumped isotope signatures in one or both orders of coral. Based on published experimental data and theoretical calculations, these biological vital effects could arise from kinetic isotope effects due to the source of carbon used for calcification, temperature- and pH-dependent rates of CO2 <span class="hlt">hydration</span> and/or hydroxylation, calcifying fluid pH, the activity of carbonic anhydrase, the residence time of dissolved inorganic carbon in the calcifying fluid, and calcification rate. A third possible explanation is the occurrence of variable acid digestion fractionation factors. Although a recent study has suggested that dolomite, <span class="hlt">calcite</span>, and aragonite may have similar clumped isotope acid digestion fractionation factors, the influence of acid digestion kinetics on Δ47 is a subject that warrants further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1335183-carbonate-clumped-isotope-signatures-aragonitic-scleractinian-calcitic-gorgonian-deep-sea-corals','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1335183-carbonate-clumped-isotope-signatures-aragonitic-scleractinian-calcitic-gorgonian-deep-sea-corals"><span>Carbonate “clumped” isotope signatures in aragonitic scleractinian and <span class="hlt">calcitic</span> gorgonian deep-sea corals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Kimball, Justine; Eagle, Robert; Dunbar, Robert</p> <p>2016-12-12</p> <p> calibrations. The offset between the corals of different mineralogy is in the same direction as published theoretical predictions for the offset between <span class="hlt">calcite</span> and aragonite although the magnitude of the offset is different. One possibility is that the deep-sea coral results reflect high-Mg and aragonite crystals attaining nominal mineral equilibrium clumped isotope signatures due to conditions of extremely slow growth. In that case, a possible explanation for the attainment of disequilibrium bulk isotope signatures and equilibrium clumped isotope signatures by deep-sea corals is that extraordinarily slow growth rates can promote the occurrence of isotopic reordering in the interfacial region of growing crystals. We also cannot rule out a component of a biological “vital effect” influencing clumped isotope signatures in one or both orders of coral. Based on published experimental data and theoretical calculations, these biological vital effects could arise from kinetic isotope effects due to the source of carbon used for calcification, temperature- and pH-dependent rates of CO2 <span class="hlt">hydration</span> and/or hydroxylation, calcifying fluid pH, the activity of carbonic anhydrase, the residence time of dissolved inorganic carbon in the calcifying fluid, and calcification rate. A third possible explanation is the occurrence of variable acid digestion fractionation factors. Although a recent study has suggested that dolomite, <span class="hlt">calcite</span>, and aragonite may have similar clumped isotope acid digestion fractionation factors, the influence of acid digestion kinetics on Δ47 is a subject that warrants further investigation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGD....1219115K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGD....1219115K"><span>Carbonate "clumped" isotope signatures in aragonitic scleractinian and <span class="hlt">calcitic</span> gorgonian deep-sea corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kimball, J.; Tripati, R. E.; Dunbar, R.</p> <p>2015-12-01</p> <p> corals of different mineralogy is in the same direction as published theoretical predictions for the offset between <span class="hlt">calcite</span> and aragonite, although the magnitude of the offset is different. One possibility is that the deep-sea coral results reflect that crystals may attain nominal mineral equilibrium clumped isotope signatures only under conditions of extremely slow growth. In that case, a possible explanation for the attainment of disequilibrium bulk isotope signatures and equilibrium clumped isotope signatures by deep-sea corals is that extraordinarily slow growth rates can promote the occurrence of isotopic reordering in the interfacial region of growing crystals. We also cannot rule out a component of a biological "vital-effect" influencing clumped isotope signatures in one or both orders of coral. Based on published experimental data and theoretical calculations, these biological "vital" effects could arise from kinetic isotope effects due to the source of carbon used for calcification, temperature- and pH-dependent rates of CO2 <span class="hlt">hydration</span> and/or hydroxylation, calcifying fluid pH, the activity of carbonic anhydrase, the residence time of dissolved inorganic carbon in the calcifying fluid, and calcification rate. A third possible explanation is the occurrence of variable acid digestion fractionation factors. Although a recent study has suggested that dolomite, <span class="hlt">calcite</span>, and aragonite may have similar clumped isotope acid digestion fractionation factors, the influence of acid digestion kinetics on Δ47 is a subject that warrants further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17993273','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17993273"><span>Growth, nitrogen fixation, yield and kernel quality of peanut in response to <span class="hlt">lime</span>, organic and inorganic fertilizer levels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Basu, Manisha; Bhadoria, P B S; Mahapatra, S C</p> <p>2008-07-01</p> <p>The aim of this investigation was to study the effect of different levels of chemical fertilizers alone and in combination with farmyard manure and <span class="hlt">lime</span> on growth, nitrogen fixation, yield and kernel quality of peanut in an acid lateritic soil. Five fertilization levels viz., no chemical fertilizer (CF) (F0), CF @ 20:40:30 (F1), CF @ 40:80:60 (F2) kg ha(-1) NPK, F1 +2.5 t ha(-1) FYM (F3) and F2 +5 t ha(-1) FYM (F4) with and without <span class="hlt">liming</span> (2 t ha(-1)) were tested. Results revealed that integrated application of FYM+CF at F3 level significantly (P0.05) improved the nitrogen content of nodules (12.4%), kernel yield (19.3%), mineral composition, oil content (4.8%), protein content (28.2%) and <span class="hlt">hydration</span> coefficient (11.6%) of kernels over sole CF at F1 level. Maximum level of CF or FYM+CF though improved the population of symbiotic nitrogen fixing bacteria in the peanut rhizosphere, however, could not improve nitrogen fixation, yield and kernel quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21130726','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21130726"><span>Influence of chemical and physical characteristics of cement kiln dusts (CKDs) on their <span class="hlt">hydration</span> behavior and potential suitability for soil stabilization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Peethamparan, Sulapha Olek, Jan Lovell, Janet</p> <p>2008-06-15</p> <p>The interaction of CKDs with a given soil depends on the chemical and physical characteristics of the CKDs. Hence, the characterization of CKDs and their <span class="hlt">hydration</span> products may lead to better understanding of their suitability as soil stabilizers. In the present article, four different CKD powders are characterized and their <span class="hlt">hydration</span> products are evaluated. A detailed chemical (X-ray diffraction), thermogravimetric and morphological (scanning electron microscope) analyses of both the CKD powders and the <span class="hlt">hydrated</span> CKD pastes are presented. In general, high free-<span class="hlt">lime</span> content ({approx} 14-29%) CKDs, when reacted with water produced significant amounts of calcium hydroxide, ettringite and syngenite. These CKDs also developed higher unconfined compressive strength and higher temperature of <span class="hlt">hydration</span> compared to CKDs with lower amounts of free-<span class="hlt">lime</span>. An attempt was made to qualitatively correlate the performance of CKD pastes with the chemical and physical characteristics of the original CKD powders and to determine their potential suitability as soil stabilizers. To that effect a limited unconfined compressive strength testing of CKD-treated kaolinite clays was performed. The results of this study suggest that both the compressive strength and the temperature of <span class="hlt">hydration</span> of the CKD paste can give early indications of the suitability of particular CKD for soil stabilization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApSS..385..616W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApSS..385..616W"><span>Molecular dynamics investigation on the adsorption behaviors of H2O, CO2, CH4 and N2 gases on <span class="hlt">calcite</span> (1 1 bar 0) surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Shimeng; Zhou, Guanggang; Ma, Yue; Gao, Lei; Song, Ranran; Jiang, Guancheng; Lu, Guiwu</p> <p>2016-11-01</p> <p>Molecular dynamics simulations (MD) were carried out to investigate the adsorption behaviors of H2O, CO2, CH4 and N2 gases, which are the main and important components in gas wells, on the <span class="hlt">calcite</span> surface at reservoir conditions. By analyzing the binding energy and Helmholtz free energy, we found that the preferential adsorption order of these four gases is: H2O > CO2 > CH4 > N2. Moreover, we have also calculated the radial distribution function profiles of the system. It shows that the H2O molecules will form two compact adsorbed layers on the surface, which denotes the <span class="hlt">calcite</span> (1 1 bar 0) surface is hydrophilic. The CO2 molecules can also form a adsorbed layer on the surface, while there are no significant features indicating that the CH4 and N2 molecules were apparently adsorbed on <span class="hlt">calcite</span> (1 1 bar 0) surface. Our calculations results can not only give a microscopic insight into the wettability of gas reservoirs but also provide theoretical instructions for <span class="hlt">hydrate</span> risk evaluation of enhanced gas recovery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5334034','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5334034"><span>Draft final risk assessment <span class="hlt">lime</span> settling basins. Version 2. 1</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1990-10-25</p> <p>The preferred alternative <span class="hlt">Lime</span> Settling Basins (LSB) Interim Response Action (IRA) selected to inhibit further migration of contaminants from the LSB included moving the stockpiled <span class="hlt">lime</span> sludge adjacent to the LSB back into the LSB, the construction of a subsurface barrier (i.e., slurry wall), placement of a soil cap and vegative cover, and the installation of a groundwater extraction system. This IRA is expected to be completed in approximately 6 months. The LSB IRA Risk Assessment (RA) presents the methodologies, quantitative and qualitative results, and assumptions used to determine if a potential risk exists to humans and biota from the activities of the LSB IRA. The activities associated with the relocation of the <span class="hlt">lime</span> sludge into the LSB and the installation of the slurry wall are the focus of this RA, since they include disturbance of soils identified as contaminated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JChPh.127p4311L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JChPh.127p4311L"><span><span class="hlt">Hydrated</span> hydride anion clusters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Han Myoung; Kim, Dongwook; Singh, N. Jiten; Kołaski, Maciej; Kim, Kwang S.</p> <p>2007-10-01</p> <p>On the basis of density functional theory (DFT) and high level ab initio theory, we report the structures, binding energies, thermodynamic quantities, IR spectra, and electronic properties of the hydride anion <span class="hlt">hydrated</span> by up to six water molecules. Ground state DFT molecular dynamics simulations (based on the Born-Oppenheimer potential surface) show that as the temperature increases, the surface-bound hydride anion changes to the internally bound structure. Car-Parrinello molecular dynamics simulations are also carried out for the spectral analysis of the monohydrated hydride. Excited-state ab initio molecular dynamics simulations show that the photoinduced charge-transfer-to-solvent phenomena are accompanied by the formation of the excess electron-water clusters and the detachment of the H radical from the clusters. The dynamics of the detachment process of a hydrogen radical upon the excitation is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998GeCoA..62..433S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeCoA..62..433S"><span>Cosmogenic Chlorine-36 Production in <span class="hlt">Calcite</span> by Muons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stone, J. O. H.; Evans, J. M.; Fifield, L. K.; Allan, G. L.; Cresswell, R. G.</p> <p>1998-02-01</p> <p>At depths below a few metres, 36Cl production in <span class="hlt">calcite</span> is initiated almost entirely by cosmic ray muons. The principal reactions are (1) direct negative muon capture by Ca; 40Ca(μ -,α) 36Cl, and (2) capture by 35Cl of secondary neutrons produced in muon capture and muon-induced photodisintegration reactions. We have determined rates for 36Cl and neutron production due to muon capture in <span class="hlt">calcite</span> from a 20 m (5360 g cm -2) depth profile in limestone. The 36Cl yield from muon capture by Ca in pure <span class="hlt">calcite</span> is 0.012 ± 0.002 atom per stopped negative muon. The surface production rate of 36Cl by muon capture on Ca in <span class="hlt">calcite</span> is, therefore, 2.1 ± 0.4 atom g -1a -1 at sea level and high latitude, approximately 11% of the production rate by Ca spallation. If it is assumed that 34% of the negative muons are captured by the Ca atom in <span class="hlt">calcite</span>, the α-yield from 40Ca following muon capture is 0.043 ± 0.008, somewhat lower than the result of a recent muon irradiation experiment (0.062 ± 0.020), but well within the extremes of existing theoretical predictions (0.0033-0.15). The average neutron yield following muon capture in pure <span class="hlt">calcite</span> is 0.44 ± 0.15 secondary neutrons per stopped negative muon, in good agreement with existing theoretical predictions. Cosmogenic isotope production by muons must be taken into account when dating young geomorphic surfaces, especially those created by excavation of only a few metres of overlying rock. Attention to isotope production by muons is also crucial to determining surface erosion rates accurately. Due to the deep penetration of muons compared to cosmic ray hadrons, the accumulation of muon-produced 36Cl is less sensitive to erosion than that of spallogenic 36Cl. Although production by muons at the surface is only a small fraction of production by spallation, the fraction of muon-produced 36Cl in rapidly eroding limestone surfaces can approach 50%. In such cases, erosion rates estimated using conventional models which attribute</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1812908G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1812908G"><span>Growth rate controlled barium partitioning in <span class="hlt">calcite</span> and aragonite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goetschl, Katja Elisabeth; Mavromatis, Vasileios; Baldermann, Andre; Purgstaller, Bettina; Dietzel, Martin</p> <p>2016-04-01</p> <p>The barium (Ba) content and the Ba/Ca molar ratios in biogenic and abiotic carbonates have been widely used from the scientific community as a geochemical proxy especially in marine and early diagenetic settings. The Ba content of carbonate minerals has been earlier associated to changes in oceanic circulation that may have been caused by upwelling, changes in weathering regimes and river-runoff as well as melt water discharge. The physicochemical controls of Ba ion incorporation in the two most abundant CaCO3 polymorphs found in Earth's surface environments, i.e. <span class="hlt">calcite</span> and aragonite, have adequately been studied only for <span class="hlt">calcite</span>. These earlier studies (i.e. [1]) suggest that at increasing growth rate, Ba partitioning in <span class="hlt">calcite</span> is increasing as well. In contrast, to date the effect of growth rate on the partitioning of Ba in aragonite remains questionable, despite the fact that this mineral phase is the predominant carbonate-forming polymorph in shallow marine environments. To shed light on the mechanisms controlling Ba ion uptake in carbonates in this study we performed steady-state Ba co-precipitation experiments with <span class="hlt">calcite</span> and aragonite at 25°C. The obtained results for the partitioning of Ba in <span class="hlt">calcite</span> are in good agreement with those reported earlier by [1], whereas those for aragonite indicate a reduction of Ba partitioning at elevated aragonite growth rates, with the partitioning coefficient value between solid and fluid to be approaching the unity. This finding is good agreement with the formation of a solid solution in the aragonite-witherite system, owing to the isostructural crystallography of the two mineral phases. Moreover, our data set provides new insights that are required for reconstructing the evolution of the Ba content of pristine marine versus diagenetically altered carbonate minerals commonly occurring in marine subfloor settings, as the thermodynamically less stable aragonite will transform to <span class="hlt">calcite</span> enriched in Ba, whilst affecting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H31D1214J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H31D1214J"><span>Fracture-aperture alteration induced by <span class="hlt">calcite</span> precipitation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jones, T.; Detwiler, R. L.</p> <p>2013-12-01</p> <p>Mineral precipitation significantly alters the transport properties of fractured rock. Chemical solubility gradients that favor precipitation induce mineral growth, which decreases the local aperture and alters preferential flow paths. Understanding the resulting development of spatial heterogeneities is necessary to predict the evolution of transport properties in the subsurface. We present experimental results that quantify the relationship between mineral precipitation and aperture alteration in a transparent analog fracture, 7.62cm x 7.62cm, with a uniform aperture of ~200 μm. Prior to flow experiments, a pump circulated a super-saturated <span class="hlt">calcite</span> solution over the bottom glass, coating the glass surface with <span class="hlt">calcite</span>. This method of seeding resulted in clusters of <span class="hlt">calcite</span> crystals with large reactive surface area and provided micro-scale variability in the aperture field. A continuous flow syringe pump injected a reactive fluid into the fracture at 0.5 ml/min. The fluid was a mixture of sodium bicarbonate (NaHCO3, 0.02M) and calcium chloride (CaCl2 0.0004M) with a saturation index, Ω, of 8.51 with respect to <span class="hlt">calcite</span>. A strobed LED panel backlit the fracture and a high-resolution CCD camera monitored changes in transmitted light intensity. Light transmission techniques provided a quantitative measurement of fracture aperture over the flow field. Results from these preliminary experiments showed growth near the inlet of the fracture, with decreasing precipitation rates in the flow direction. Over a period of two weeks, the fracture aperture decreased by 17% within the first 4mm of the inlet. Newly precipitated <span class="hlt">calcite</span> bridged individual crystal clusters and smoothed the reacting surface. This observation is an interesting contradiction to the expectation of surface roughening induced by mineral growth. Additionally, the aperture decreased uniformly across the width of the fracture due to the initial aperture distribution. Future experiments of precipitation</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6495179','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6495179"><span>Value of periangiography <span class="hlt">hydration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kerstein, M D; Puyau, F A</p> <p>1984-11-01</p> <p>The value of contrast dye to the planning and evaluation of cardiovascular disease cannot be overestimated. However, adverse renal sequellae may cause the surgeon to hesitate in obtaining an arteriogram, especially in patients with compromised renal function. The purpose of this study was to evaluate the incidence of renal dysfunction in patients requiring angiography. Standard contrast angiography for cerebral or peripheral vascular disease was administered to 150 consecutive patients (89 men and 61 women), with an average age of 63.3 years (range 49 to 89 years). All patients received 100 to 150 ml of dye, with a concentration of approximately 50% iodine. Patients were <span class="hlt">hydrated</span> with 0.5 N saline/5% dextrose, intravenously, for 8 hours before the procedure (1 to 3 ml/kg/hr). In 31 patients (11 women and 20 men) the serum BUN and/or creatinine levels were elevated (mean BUN value of 48 +/- 9 mg/dl; mean creatinine level of 2.8 +/- 0.6 mg/dl). The patients with abnormal renal function received an additional 300 to 500 ml of intravenous fluid, plus 20 to 40 mg intravenous furosemide, 1 hour before roentgenography to establish a diuresis. All patients were <span class="hlt">hydrated</span> for 6 hours after angiography with the same solution at the same rate (1 to 3 ml/kg/hr). There were no episodes of compromised renal or cardiopulmonary dysfunction because of contrast angiography. In no patient did the BUN or creatinine level rise, nor was there evidence of acute tubular necrosis, as documented by oliguria and abnormal cells in the urine. Angiography is a safe procedure, even with patients who may have compromised renal function, if appropriate prehydration/posthydration and diuretic measures are undertaken.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=182523&keyword=wind+AND+tunnel&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90550376&CFTOKEN=31112438','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=182523&keyword=wind+AND+tunnel&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90550376&CFTOKEN=31112438"><span>EVALUATION OF BIOAEROSOL COMPONENTS, GENERATION FACTORS, AND AIRBORNE TRANSPORT ASSOCIATED WITH <span class="hlt">LIME</span> TREATMENT OF CONTAMINATED SEDIMENT</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><span class="hlt">Lime</span> treatment has been used in contaminated sediment management activities for many purposes such as dewatering, improvement of physical properties, and reducing contaminant mobility. Exothermic volatilization of volatile organic compounds from <span class="hlt">lime</span>-treated sediment is well kno...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=129077&keyword=Beryllium&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78675952&CFTOKEN=77492947','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=129077&keyword=Beryllium&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=78675952&CFTOKEN=77492947"><span>REMOVAL OF BERYLLIUM FROM DRINKING WATER BY CHEMICAL COAGULATION AND <span class="hlt">LIME</span> SOFTENING</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The effectiveness of conventional drinking water treatment and <span class="hlt">lime</span> softening was evaluated for beryllium removal from two drinking water sources. ar test studies were conducted to determine how common coagulants (aluminum sulfate and ferric chloride and <span class="hlt">lime</span> softening performed ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/914210','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/914210"><span><span class="hlt">Liming</span> Poultry Manures to Kill Pathogens and Decrease Soluble Phosphorus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Maguire,R.; Hesterberg, D.; Gernat, A.; Anderson, K.; Wineland, M.; Grimes, J.</p> <p>2006-01-01</p> <p>Received for publication September 9, 2005. Stabilizing phosphorus (P) in poultry waste to reduce P losses from manured soils is important to protect surface waters, while pathogens in manures are an emerging issue. This study was conducted to evaluate CaO and Ca(OH){sub 2} for killing manure bacterial populations (pathogens) and stabilizing P in poultry wastes and to investigate the influence on soils following amendment with the treated wastes. Layer manure and broiler litter varying in moisture content were treated with CaO and Ca(OH){sub 2} at rates of 2.5, 5, 10, and 15% by weight. All treated wastes were analyzed for microbial plate counts, pH, and water-soluble phosphorus (WSP), while a few selected layer manures were analyzed by phosphorus X-ray absorption near edge structure (XANES). A loamy sand and a silt loam were amended with broiler litter and layer manure treated with CaO at rates of 0, 2.5, 5, 10, and 15% and soil WSP and pH were measured at times 1, 8, and 29 d. <span class="hlt">Liming</span> reduced bacterial populations, with greater rates of <span class="hlt">lime</span> leading to greater reductions; for example 10% CaO applied to 20% solids broiler litter reduced the plate counts from 793 000 to 6500 mL{sup -1}. <span class="hlt">Liming</span> also reduced the WSP in the manures by over 90% in all cases where at least 10% CaO was added. <span class="hlt">Liming</span> the manures also reduced WSP in soils immediately following application and raised soil pH. The <span class="hlt">liming</span> process used successfully reduced plate counts and concerns about P losses in runoff following land application of these <span class="hlt">limed</span> products due to decreased WSP.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/863671','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/863671"><span>Catalytic iron oxide for <span class="hlt">lime</span> regeneration in carbonaceous fuel combustion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Shen, Ming-Shing; Yang, Ralph T.</p> <p>1980-01-01</p> <p><span class="hlt">Lime</span> utilization for sulfurous oxides absorption in fluidized combustion of carbonaceous fuels is improved by impregnation of porous <span class="hlt">lime</span> particulates with iron oxide. The impregnation is achieved by spraying an aqueous solution of mixed iron sulfate and sulfite on the limestone before transfer to the fluidized bed combustor, whereby the iron compounds react with the limestone substrate to form iron oxide at the limestone surface. It is found that iron oxide present in the spent limestone acts as a catalyst to regenerate the spent limestone in a reducing environment. With only small quantities of iron oxide the calcium can be recycled at a significantly increased rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JCrGr.338..147F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JCrGr.338..147F"><span>The effect of sulfated polysaccharides on the crystallization of <span class="hlt">calcite</span> superstructures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fried, Ruth; Mastai, Yitzhak</p> <p>2012-01-01</p> <p><span class="hlt">Calcite</span> with unique morphology and uniform size has been successfully synthesized in the presence of classes of polysaccharides based on carrageenans. In the crystallization of <span class="hlt">calcite</span>, the choice of different carrageenans, (iota, lambda and kappa), as additives concedes systematic study of the influence of different chemical structures and particularly molecular charge on the formation of CaCO 3 crystals. The uniform <span class="hlt">calcite</span> superstructures are formed by assemblies and aggregation of <span class="hlt">calcite</span> crystals. The mechanism for the formation of <span class="hlt">calcite</span> superstructures was studied by a variety of techniques, SEM, TEM, XRD, time-resolved conductivity and light scattering measurements, focusing on the early stages of crystals' nucleation and aggregation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018448','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018448"><span>Imaging surface contacts: Power law contact distributions and contact stresses in quartz, <span class="hlt">calcite</span>, glass and acrylic plastic</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dieterich, J.H.; Kilgore, B.D.</p> <p>1996-01-01</p> <p>A procedure has been developed to obtain microscope images of regions of contact between roughened surfaces of transparent materials, while the surfaces are subjected to static loads or undergoing frictional slip. Static loading experiments with quartz, <span class="hlt">calcite</span>, soda-<span class="hlt">lime</span> glass and acrylic plastic at normal stresses to 30 MPa yield power law distributions of contact areas from the smallest contacts that can be resolved (3.5 ??m2) up to a limiting size that correlates with the grain size of the abrasive grit used to roughen the surfaces. In each material, increasing normal stress results in a roughly linear increase of the real area of contact. Mechanisms of contact area increase are by growth of existing contacts, coalescence of contacts and appearance of new contacts. Mean contacts stresses are consistent with the indentation strength of each material. Contact size distributions are insensitive to normal stress indicating that the increase of contact area is approximately self-similar. The contact images and contact distributions are modeled using simulations of surfaces with random fractal topographies. The contact process for model fractal surfaces is represented by the simple expedient of removing material at regions where surface irregularities overlap. Synthetic contact images created by this approach reproduce observed characteristics of the contacts and demonstrate that the exponent in the power law distributions depends on the scaling exponent used to generate the surface topography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatMa..15..903K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatMa..15..903K"><span>Tuning hardness in <span class="hlt">calcite</span> by incorporation of amino acids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Yi-Yeoun; Carloni, Joseph D.; Demarchi, Beatrice; Sparks, David; Reid, David G.; Kunitake, Miki E.; Tang, Chiu C.; Duer, Melinda J.; Freeman, Colin L.; Pokroy, Boaz; Penkman, Kirsty; Harding, John H.; Estroff, Lara A.; Baker, Shefford P.; Meldrum, Fiona C.</p> <p>2016-08-01</p> <p>Structural biominerals are inorganic/organic composites that exhibit remarkable mechanical properties. However, the structure-property relationships of even the simplest building unit--mineral single crystals containing embedded macromolecules--remain poorly understood. Here, by means of a model biomineral made from <span class="hlt">calcite</span> single crystals containing glycine (0-7 mol%) or aspartic acid (0-4 mol%), we elucidate the origin of the superior hardness of biogenic <span class="hlt">calcite</span>. We analysed lattice distortions in these model crystals by using X-ray diffraction and molecular dynamics simulations, and by means of solid-state nuclear magnetic resonance show that the amino acids are incorporated as individual molecules. We also demonstrate that nanoindentation hardness increased with amino acid content, reaching values equivalent to their biogenic counterparts. A dislocation pinning model reveals that the enhanced hardness is determined by the force required to cut covalent bonds in the molecules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.148..343S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.148..343S"><span>U(VI) behaviour in hyperalkaline <span class="hlt">calcite</span> systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, Kurt F.; Bryan, Nicholas D.; Swinburne, Adam N.; Bots, Pieter; Shaw, Samuel; Natrajan, Louise S.; Mosselmans, J. Frederick W.; Livens, Francis R.; Morris, Katherine</p> <p>2015-01-01</p> <p>The behaviour of U(VI) in hyperalkaline fluid/<span class="hlt">calcite</span> systems was studied over a range of U(VI) concentrations (5.27 × 10-5 μM to 42.0 μM) and in two high pH systems, young and old synthetic cement leachate in batch sorption experiments. These systems were selected to be representative of young- (pH 13.3) and old-stage (pH 10.5) leachate evolution within a cementitious geological disposal facility. Batch sorption experiments, modelling, extended X-ray absorption fine structure spectroscopy, electron microscopy, small angle X-ray scattering and luminescence spectroscopy were used to define the speciation of U(VI) across the systems of study. At the lowest concentrations (5.27 × 10-5 μM 232U(VI)) significant U removal was observed for both old and young cement leachates, and this was successfully modelled using a first order kinetic adsorption modelling approach. At higher concentrations (>4.20 μM) in the young cement leachate, U(VI) showed no interaction with the <span class="hlt">calcite</span> surface over an 18 month period. Small angle X-ray scattering techniques indicated that at high U concentrations (42.0 μM) and after 18 months, the U(VI) was present in a colloidal form which had little interaction with the <span class="hlt">calcite</span> surface and consisted of both primary and aggregated particles with a radius of 7.6 ± 1.1 and 217 ± 24 Å, respectively. In the old cement leachate, luminescence spectroscopy identified two surface binding sites for U(VI) on <span class="hlt">calcite</span>: in the system with 0.21 μM U(VI), a liebigite-like Ca2UO2(CO3)3 surface complex was identified; at higher U(VI) concentrations (0.42 μM), a second binding site of undetermined coordination was identified. At elevated U(VI) concentrations (>2.10 μM) in old cement leachate, both geochemical data and luminescence spectroscopy suggested that surface mediated precipitation was controlling U(VI) behaviour. A focused ion beam mill was used to create a section across the U(VI) precipitate-<span class="hlt">calcite</span> interface. Transmission electron</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol23/pdf/CFR-2010-title40-vol23-sec180-1231.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol23/pdf/CFR-2010-title40-vol23-sec180-1231.pdf"><span>40 CFR 180.1231 - <span class="hlt">Lime</span>; exemption from the requirement of a tolerance.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 40 Protection of Environment 23 2010-07-01 2010-07-01 false <span class="hlt">Lime</span>; exemption from the requirement... From Tolerances § 180.1231 <span class="hlt">Lime</span>; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of <span class="hlt">lime</span>....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol24/pdf/CFR-2014-title40-vol24-sec180-1232.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol24/pdf/CFR-2014-title40-vol24-sec180-1232.pdf"><span>40 CFR 180.1232 - <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 40 Protection of Environment 24 2014-07-01 2014-07-01 false <span class="hlt">Lime</span>-sulfur; exemption from the... Exemptions From Tolerances § 180.1232 <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of <span class="hlt">lime</span>-sulfur....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol25/pdf/CFR-2013-title40-vol25-sec180-1232.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol25/pdf/CFR-2013-title40-vol25-sec180-1232.pdf"><span>40 CFR 180.1232 - <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 40 Protection of Environment 25 2013-07-01 2013-07-01 false <span class="hlt">Lime</span>-sulfur; exemption from the... Exemptions From Tolerances § 180.1232 <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of <span class="hlt">lime</span>-sulfur....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol25/pdf/CFR-2012-title40-vol25-sec180-1232.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol25/pdf/CFR-2012-title40-vol25-sec180-1232.pdf"><span>40 CFR 180.1232 - <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 40 Protection of Environment 25 2012-07-01 2012-07-01 false <span class="hlt">Lime</span>-sulfur; exemption from the... Exemptions From Tolerances § 180.1232 <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of <span class="hlt">lime</span>-sulfur....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol24/pdf/CFR-2011-title40-vol24-sec180-1232.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol24/pdf/CFR-2011-title40-vol24-sec180-1232.pdf"><span>40 CFR 180.1232 - <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 40 Protection of Environment 24 2011-07-01 2011-07-01 false <span class="hlt">Lime</span>-sulfur; exemption from the... Exemptions From Tolerances § 180.1232 <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of <span class="hlt">lime</span>-sulfur....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol23/pdf/CFR-2010-title40-vol23-sec180-1232.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol23/pdf/CFR-2010-title40-vol23-sec180-1232.pdf"><span>40 CFR 180.1232 - <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 40 Protection of Environment 23 2010-07-01 2010-07-01 false <span class="hlt">Lime</span>-sulfur; exemption from the... Exemptions From Tolerances § 180.1232 <span class="hlt">Lime</span>-sulfur; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of <span class="hlt">lime</span>-sulfur....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GBioC..16.1065S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GBioC..16.1065S"><span>Planktic foraminiferal sedimentation and the marine <span class="hlt">calcite</span> budget</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schiebel, Ralf</p> <p>2002-12-01</p> <p>The vertical flux and sedimentation rate of planktic foraminiferal tests are quantified and a global planktic foraminiferal CaCO3 budget is presented. Test and <span class="hlt">calcite</span> flux rates are calculated according to the distribution of species obtained from multinet and sediment trap samples. Modern planktic foraminiferal population dynamics are discussed as a prerequisite for the quantification of the <span class="hlt">calcite</span> budget, highlighting the importance of ecological, autecological (e.g., reproduction), and biogeochemical conditions that determine the presence or absence of species. To complete the open-marine, particulate CaCO3 inventory, the contribution of coccolithophores, pteropods, and calcareous dinophytes is discussed. Based on the studied regions, the global planktic foraminiferal <span class="hlt">calcite</span> flux rate at 100 m depth amounts to 1.3-3.2 Gt yr-1, equivalent to 23-56% of the total open marine CaCO3 flux. The preservation of tests varies on a regional and temporal scale, and is affected by local hydrography and dissolution. During most of the year (off-peak periods), many tests dissolve above 700-m water depth while settling through the water column, with on average only 1-3% of the initially exported CaCO3 reaching the deep-seafloor. Pulsed flux events, mass dumps of fast settling particles, yield a major contribution of tests to the formation of deep-sea sediments. On average, ˜25% of the initially produced planktic foraminiferal test CaCO3 settles on the seafloor. The total planktic foraminiferal contribution of CaCO3 to global surface sediments amounts to 0.36-0.88 Gt yr-1, ˜32-80% of the total deep-marine <span class="hlt">calcite</span> budget.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5438497','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5438497"><span>Interaction of copper with the surface of <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Franklin, M.L.; Morse, J.W.</p> <p>1981-05-01</p> <p>The interaction of Cu ions in solution with the surface of <span class="hlt">calcite</span> has been studied in a range of solutions from pure water to seawater. Observations of the uptake of Cu from solution onto <span class="hlt">calcite</span> indicates that the process is rapid and strong in both distilled water and seawater. In distilled water, Cu uptake is directly proportional to the concentration of Cu in solution; Cu/sub s/ = K/sub s/Cu/sub 1/. This Cu/sub s/ dependence on Cu/sub 1/ is linear over the entire Cu concentration range studied (0.1 to 200 ..mu..M). Results do not indicate the formation of a precipitate of either malachite or copper carbonate. In seawater, the uptake of Cu is also directly proportional to the concentration of Cu/sub 1/ up to a limiting value of approximately 13 ..mu..M. The average value for K/sub s/ in seawater, 0.24 +- 0.06 (Cu/sub 1/ less than or equal to 13 ..mu..M), is approximately an order of magnitude less than in distilled water. This is probably the result of smaller Cu/sub 1/ activity coefficients and increased site competition by other ions in seawater. Attempts to increase the Cu/sub 1/ concentration above 13 ..mu..M resulted in the additional Cu being deposited on the surface of the <span class="hlt">calcite</span>. A possible explanation for this behavior is the formation of a precipitate of malachite on the <span class="hlt">calcite</span> surface. The value of K/sub s/ decreased slightly with increasing solid to solution ratios in seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/15010163','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/15010163"><span>Variation in <span class="hlt">Calcite</span> Dissolution Rates: A Fundamental Problem?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arvidson, Rolf S.; Ertan, Inci E.; Amonette, James E.; Luttge, Andreas</p> <p>2003-05-01</p> <p>A comparison of published <span class="hlt">calcite</span> dissolution rates measured far from equilibrium at a pH of {approx} 6 and above shows well over an order of magnitude in variation. Recently published AFM step velocities extend this range further still. In an effort to understand the source of this variation, and to provide additional constraint from a new analytical approach, we have measured dissolution rates by vertical scanning interferometry. In areas of the <span class="hlt">calcite</span> cleavage surface dominated by etch pits, our measured dissolution rate is 10{sup 10.95} mol/cm{sup 2}/s (PCO{sub 2} 10{sup 3.41} atm, pH 8.82), 5 to {approx}100 times slower than rates published in bulk powder experiments, although similar to rates derived from AFM step velocities. On cleavage surfaces free of local etch pit development, dissolution is limited by a slow, ''global'' rate (10{sup 11.68} mol/cm{sup 2}/s). Although these differences confirm the importance of etch pit (defect) distribution as a controlling mechanism in <span class="hlt">calcite</span> dissolution, they also suggest that ''bulk'' <span class="hlt">calcite</span> dissolution rates observed in powder experiments may derive substantial enhancement from grain boundaries having high step and kink density. We also observed significant rate inhibition by introduction of dissolved manganese. At 2.0 {micro}M Mn, the rate diminished to 10{sup 12.4} mol/cm{sup 2}/s, and the well formed rhombic etch pits that characterized dissolution in pure solution were absent. These results are in good agreement with the pattern of manganese inhibition in published AFM step velocities, assuming a step density on smooth terraces of {approx} 9 {micro}m{sup -1}.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27502176','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27502176"><span>Magnesium-<span class="hlt">Calcite</span> Crystal Formation Mediated by the Thermophilic Bacterium Geobacillus thermoglucosidasius Requires Calcium and Endospores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Murai, Rie; Yoshida, Naoto</p> <p>2016-11-01</p> <p>Fresh Geobacillus thermoglucosidasius cells grown on soybean-casein digest nutrient agar were inoculated as a parent colony 1 cm in diameter on the surface of an agar gel containing acetate and calcium ions (<span class="hlt">calcite</span>-promoting hydrogel) and incubated at 60 °C for 4 days, after which magnesium-<span class="hlt">calcite</span> single crystals of 50-130 µm in size formed within the parent colony. Addition of EDTA, polyacrylic acid or N,N-dicyclohexylcarbodiimide to the <span class="hlt">calcite</span>-forming hydrogel inhibited the parent colony from forming magnesium-<span class="hlt">calcite</span> crystals. Inoculation of G. thermoglucosidasius on <span class="hlt">calcite</span>-forming hydrogel containing 5 µM cadmium and 20 µM zinc resulted in a decrease in the sporulation rate from 55 to 7-8 %. Magnesium-<span class="hlt">calcite</span> synthesis decreased relative to the sporulation rate. G. thermoglucosidasius exhibited higher adsorption/absorbance of calcium than other Geobacillus sp. that do not mediate <span class="hlt">calcite</span> formation and higher levels of magnesium accumulation. Calcium ions contained in the <span class="hlt">calcite</span>-promoting hydrogel and magnesium ions concentrated in G. thermoglucosidasius cells serve as the elements for magnesium-<span class="hlt">calcite</span> synthesis. The observed decreases in sporulation rate and magnesium-<span class="hlt">calcite</span> formation support the hypothesis that endospores act as nuclei for the synthesis of magnesium-<span class="hlt">calcite</span> single crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018861','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018861"><span>Chemistry and petrography of <span class="hlt">calcite</span> in the KTB pilot borehole, Bavarian Oberpfalz, Germany</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Komor, S.C.</p> <p>1995-01-01</p> <p>The KTB pilot borehole in northeast Bavaria, Germany, penetrates 4000 m of gneiss, amphibolite, and subordinate calc-silicate, lamprophyre and metagabbro. There are three types of <span class="hlt">calcite</span> in the drilled section: 1) metamorphic <span class="hlt">calcite</span> in calc-silicate and marble; 2) crack-filling <span class="hlt">calcite</span> in all lithologies; and 3) replacement <span class="hlt">calcite</span> in altered minerals. Crack-filling and replacement <span class="hlt">calcite</span> postdate metamorphic <span class="hlt">calcite</span>. Multiple <span class="hlt">calcite</span> generations in individual cracks suggest that different generations of water repeatedly flowed through the same cracks. Crack-filling mineral assemblages that include <span class="hlt">calcite</span> originally formed at temperatures of 150-350??C. Presently, crack-filling <span class="hlt">calcite</span> is in chemical and isotopic equilibrium with saline to brackish water in the borehole at temperatures of ???120??C. The saline to brackish water contains a significant proportion of meteoric water. Re-equilibration of crack-filling <span class="hlt">calcite</span> to lower temperatures means that <span class="hlt">calcite</span> chemistry tells us little about water-rock interactions in the crystal section of temperatures higher than ~120??C. -from Author</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3623123','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3623123"><span>Geobacillus thermoglucosidasius Endospores Function as Nuclei for the Formation of Single <span class="hlt">Calcite</span> Crystals</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Murai, Rie</p> <p>2013-01-01</p> <p>Geobacillus thermoglucosidasius colonies were placed on an agar hydrogel containing acetate, calcium ions, and magnesium ions, resulting in the formation of single <span class="hlt">calcite</span> crystals (<span class="hlt">calcites</span>) within and peripheral to the plating area or parent colony. Microscopic observation of purified <span class="hlt">calcites</span> placed on the surface of soybean casein digest (SCD) nutrient medium revealed interior crevices from which bacterial colonies originated. <span class="hlt">Calcites</span> formed on the gel contained [1-13C]- and [2-13C]acetate, demonstrating that G. thermoglucosidasius utilizes carbon derived from acetate for <span class="hlt">calcite</span> formation. During <span class="hlt">calcite</span> formation, vegetative cells swam away from the parent colony in the hydrogel. Hard-agar hydrogel inhibited the formation of <span class="hlt">calcites</span> peripheral to the parent colony. The <span class="hlt">calcite</span> dissolved completely in 1 M HCl, with production of bubbles, and the remaining endospore-like particles were easily stained with Brilliant green dye. The presence of DNA and protein in <span class="hlt">calcites</span> was demonstrated by electrophoresis. We propose that endospores initiate the nucleation of <span class="hlt">calcites</span>. Endospores of G. thermoglucosidasius remain alive and encapsulated in <span class="hlt">calcites</span>. PMID:23455343</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/826394','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/826394"><span>Microbially-Mediated Subsurface <span class="hlt">Calcite</span> Precipitation for Removal of Hazardous Divalent Cations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Colwell, Frederick S.; Smith, R.W.; Ferris, F. Gratn; Ingram, Jani C.; Reysenbach, A.-L.; Fujita, Yoshiko; Tyler, T.L.; Taylor, J.L.; Banta, A.; Delwiche, M.E.; McLing, T.; Cortez, Marnie, M.; Watwood, M.E.</p> <p>2003-03-27</p> <p>We are investigating microbially-mediated acceleration of <span class="hlt">calcite</span> precipitation and co-precipitation of hazardous divalent cations (e.g., 90Sr) in <span class="hlt">calcite</span> saturated subsurface systems. In theory, the addition of urea to an aquifer or vadose zone and its subsequent hydrolysis by indigenous microbes will cause an increase in alkalinity, pH and <span class="hlt">calcite</span> precipitation. Lab studies indicated the ability of various bacteria to precipitate <span class="hlt">calcite</span> through urea hydrolysis and that incorporation of strontium in biogenically-formed <span class="hlt">calcite</span> is greater than in abiotically formed <span class="hlt">calcite</span>. Results from a field experiment in a pristine location in the Snake River Plain aquifer involving the phased addition of molasses and then urea showed increases in total cell numbers, rate of urea hydrolysis and <span class="hlt">calcite</span> formation during the study. The combined diagnostic approaches of microbiology, molecular ecology and analytical chemistry demonstrate the feasibility of this biogeochemical manipulation for subsurface remediation at arid Western DOE sites such as Hanford and INEEL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23036948','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23036948"><span>Evaluation of strengthening mechanisms in <span class="hlt">calcite</span> single crystals from mollusk shells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kunitake, Miki E; Mangano, Lauren M; Peloquin, John M; Baker, Shefford P; Estroff, Lara A</p> <p>2013-02-01</p> <p>Biogenic single-crystal <span class="hlt">calcite</span> is often reported to be harder and tougher than geologic <span class="hlt">calcite</span> in the form of Iceland spar. However, the mechanistic origins of the superior mechanical properties of the biogenic materials are still debated. We investigate the hardness and modulus of biogenic <span class="hlt">calcite</span> from the prismatic layer of the mollusk Atrina rigida compared with a pure geologic <span class="hlt">calcite</span>, Iceland spar. On the {001} face, biogenic <span class="hlt">calcite</span> is found to be 50-70% harder than geologic <span class="hlt">calcite</span>. This range is due to the fact that changes in azimuthal angle of the indenter tip lead to a hardness variation of ∼20% in A. rigida but only ∼7% in Iceland spar. The higher hardness and increased anisotropy of biogenic <span class="hlt">calcite</span> could be accounted for by hardening mechanisms based on hindered dislocation motion rather than crack deflection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21963207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21963207"><span>Interactions of salicylic acid derivatives with <span class="hlt">calcite</span> crystals.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ukrainczyk, Marko; Gredičak, Matija; Jerić, Ivanka; Kralj, Damir</p> <p>2012-01-01</p> <p>Investigation of basic interactions between the active pharmaceutical compounds and calcium carbonates is of great importance because of the possibility to use the carbonates as a mineral carrier in drug delivery systems. In this study the mode and extent of interactions of salicylic acid and its amino acid derivates, chosen as pharmaceutically relevant model compounds, with <span class="hlt">calcite</span> crystals are described. Therefore, the crystal growth kinetics of well defined rhombohedral <span class="hlt">calcite</span> seed crystals in the systems containing salicylic acid (SA), 5-amino salicylic acid (5-ASA), N-salicyloil-l-aspartic acid (N-Sal-Asp) or N-salicyloil-l-glutamic acid (N-Sal-Glu), were investigated. The precipitation systems were of relatively low initial supersaturation and of apparently neutral pH. The data on the crystal growth rate reductions in the presence of the applied salicylate molecules were analyzed by means of Cabrera & Vermileya's, and Kubota & Mullin's models of interactions of the dissolved additives and crystal surfaces. The crystal growth kinetic experiments were additionally supported with the appropriate electrokinetic, spectroscopic and adsorption measurements. The Langmuir adsorption constants were determined and they were found to be in a good correlation with values obtained from crystal growth kinetic analyses. The results indicated that salicylate molecules preferentially adsorb along the steps on the growing <span class="hlt">calcite</span> surfaces. The values of average spacing between the adjacent salicylate adsorption active sites and the average distance between the neighboring adsorbed salicylate molecules were also estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5322967','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5322967"><span><span class="hlt">Calcite</span> deposition at Miravalles geothermal field, Costa Rica</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vaca, L.; Alvarado, A.; Corrales, R. )</p> <p>1989-01-01</p> <p>The <span class="hlt">calcite</span> deposition problem at Miravalles has been studied since it was observed in the first three wells drilled on the slopes of the Miravalles Volcano. Long-term tests have been carried out to study reservoir characteristics. The change in the production behavior of the wells with the restriction imposed by the deposited <span class="hlt">calcite</span> has been studied trying to evaluate and quantify the scaling problem. Work is being done on predictions of the deposition rate, location and distribution of the deposited mineral inside the wells. This work was compared with real data obtained from caliper logs of the wells before and after production. The feasibility of the first 55 MW power plant has been demonstrated. It was considered that the solution for the <span class="hlt">calcite</span> problem is the reaming during discharge of the wells trying at the same time to minimize the cleaning interventions with a new well design. It is believed, due to the thermodynamics and chemical characteristics of the extracted fluids, that it is possible to find a non-deposition zone which will permit the drilling of wells without a scaling problem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17242744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17242744"><span>Heterogeneous conversion of <span class="hlt">calcite</span> aerosol by nitric acid.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Preszler Prince, A; Grassian, V H; Kleiber, P; Young, M A</p> <p>2007-02-07</p> <p>The reaction of nitric acid with <span class="hlt">calcite</span> aerosol at varying relative humidities has been studied under suspended particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reactant concentration in the chamber, as well as the appearance of gas phase products and surface adsorbed species, was spectroscopically monitored before and after mixing with CaCO(3) (<span class="hlt">calcite</span>) particles. The interaction with HNO(3) was found to lead to gas phase CO(2) evolution and increased water uptake due to heterogeneous conversion of the carbonate to particulate nitrate. The reaction was enhanced as the relative humidity of the system was increased, especially at relative humidities above the reported deliquescence point of particulate Ca(NO(3))(2). The measured reaction extent demonstrates that the total <span class="hlt">calcite</span> particulate mass is available for reaction with HNO(3) and the conversion process is not limited to the particle surface. The spectroscopy of the surface formed nitrate suggests a highly concentrated solution environment with a significant degree of ion pairing. The implications of the HNO(3) loss and the formation of the particulate nitrate product for atmospheric chemistry are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999Geo....27..347K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999Geo....27..347K"><span>Alternative origins for nannobacteria-like objects in <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirkland, Brenda L.; Lynch, F. Leo; Rahnis, Michael A.; Folk, Robert L.; Molineux, Ian J.; McLean, Robert J. C.</p> <p>1999-04-01</p> <p>More than 40 <span class="hlt">calcite</span>-precipitation experiments were performed under sterile conditions in order to investigate the origins of 25 300 nm spherical-, rod-, and ovoid-shaped objects that have been widely interpreted as evidence of nanometer-scale life (i.e., nannobacteria). Individual experiments included the addition of soluble organic compounds, common species of eubacteria, or phage-induced eubacterial lysates. These experiments indicate that many of the nanometer-scale objects have inorganic or nonnannobacterial origins. In the precipitation experiments, <span class="hlt">calcite</span> formed euhedral crystals 50 800 nm in diameter and smaller (<50 nm) anhedral or rounded particles or protocrystals. The small anhedral or rounded solids resembled nannobacteria. The relative amount of anhedral or rounded <span class="hlt">calcite</span> was greatest in experiments with a dissolved organic component. These controlled experiments are in accord with observations that rounded nanometer-scale objects are more common in minerals formed in organic-rich environments. Bacterial fragments occur as rounded to irregularly shaped particles that included cell-wall fragments, expulsed cytoplasm, and relict capsules that also closely resembled nannobacteria. Acid etching of the large euhedral crystals produced in the precipitation experiments also resulted in the formation of nanometer-scale features that resembled nannobacteria in natural carbonates. The shapes of the etching artifacts vary as a function of the strength of the acid and the duration of etching. Much caution is advisable in interpreting the origin of rounded features <50 nm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.123..351V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.123..351V"><span>Earthworm-produced <span class="hlt">calcite</span> granules: A new terrestrial palaeothermometer?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Versteegh, Emma A. A.; Black, Stuart; Canti, Matthew G.; Hodson, Mark E.</p> <p>2013-12-01</p> <p>In this paper we show for the first time that <span class="hlt">calcite</span> granules, produced by the earthworm Lumbricus terrestris, and commonly recorded at sites of archaeological interest, accurately reflect temperature and soil water δ18O values. Earthworms were cultivated in an orthogonal combination of two different (granule-free) soils moistened by three types of mineral water and kept at three temperatures (10, 16 and 20 °C) for an acclimatisation period of three weeks followed by transfer to identical treatments and cultivation for a further four weeks. Earthworm-secreted <span class="hlt">calcite</span> granules were collected from the second set of soils. δ18O values were determined on individual <span class="hlt">calcite</span> granules (δ18Oc) and the soil solution (δ18Ow). The δ18Oc values reflect soil solution δ18Ow values and temperature, but are consistently enriched by 1.51 (± 0.12)‰ in comparison to equilibrium in synthetic carbonates. The data fit the equation 1000 ln α = [20.21 ± 0.92] (103 T-1) - [38.58 ± 3.18] (R2 = 0.95; n = 96; p < 0.0005). As the granules are abundant in modern soils, buried soils and archaeological contexts, and can be dated using U-Th disequilibria, the developed palaeotemperature relationship has enormous potential for application to Holocene and Pleistocene time intervals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25233226','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25233226"><span>Nucleation, growth and evolution of calcium phosphate films on <span class="hlt">calcite</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Naidu, Sonia; Scherer, George W</p> <p>2014-12-01</p> <p>Marble, a stone composed of the mineral <span class="hlt">calcite</span>, is subject to chemically induced weathering in nature due to its relatively high dissolution rate in acid rain. To protect monuments and sculpture from corrosion, we are investigating the application of thin layers of hydroxyapatite (HAP) onto marble. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with <span class="hlt">calcite</span>. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate salt was reacted with marble, alone and with cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP layers on marble. Nucleation and growth on the <span class="hlt">calcite</span> substrate was studied, as well as metastable phase evolution, using scanning electron microscopy, grazing incidence X-ray diffraction, and atomic force microscopy. Film nucleation was enhanced by surface roughness. The rate of nucleation and the growth rate of the film increased with cationic (calcium) and anionic (carbonate) precursor additions. Calcium additions also influenced phase formation, introducing a metastable phase (octacalcium phosphate) and a different phase evolution sequence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20579928','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20579928"><span>Visualization of acoustic cavitation effects on suspended <span class="hlt">calcite</span> crystals.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wagterveld, R M; Boels, L; Mayer, M J; Witkamp, G J</p> <p>2011-01-01</p> <p>The acoustic cavitation (42,080 Hz, 7.1 W cm(-2) or 17 W) effects on suspended <span class="hlt">calcite</span> crystals, sized between 5 and 50 μm, have been visualized for the first time using high speed photography. High speed recordings with a duration of 1 s containing up to 300,000 frames per second, revealed the effect of cluster and streamer cavitation on several <span class="hlt">calcite</span> crystals. Cavitation clusters, evolved from cavitation inception and collapse, caused attrition, disruption of aggregates and deagglomeration, whereas streamer cavitation was observed to cause deagglomeration only. Cavitation on the surface gave the crystals momentum. However, it is shown that breakage of accelerated crystals by interparticle collisions is unrealistic because of their small sizes and low velocities. Crystals that were accelerated by bubble expansion, subsequently experienced a deceleration much stronger than expected from drag forces, upon bubble collapse. Experiments with pre-dried crystals seemed to support the current theory on bubble nucleation through the presence of pre-existing gas pockets. However, experiments with fully wetted crystals also showed the nucleation of bubbles on the crystal surface. Although microjet impingement on the crystal surface could not be directly visualized with high speed photography, scanning electron microscopy (SEM) analysis of irradiated <span class="hlt">calcite</span> seeds showed deep circular indentations. It was suggested that these indentations might be caused by shockwave induced jet impingement. Furthermore, the appearance of voluminous fragments with large planes of fracture indicated that acoustic cavitation can also cause the breakage of single crystal structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17806883','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17806883"><span>Obsidian <span class="hlt">hydration</span> dates glacial loading?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Friedman, I; Pierce, K L; Obradovich, J D; Long, W D</p> <p>1973-05-18</p> <p>Three different groups of <span class="hlt">hydration</span> rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of <span class="hlt">hydration</span> rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average <span class="hlt">hydration</span> rind thicknesses of 14.5 and 7.9 micrometers. These later two <span class="hlt">hydration</span> rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1003714','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1003714"><span>Obsidian <span class="hlt">Hydration</span>: A New Paleothermometer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Anovitz, Lawrence {Larry} M; Riciputi, Lee R; Cole, David R; Fayek, Mostafa; Elam, J. Michael</p> <p>2006-01-01</p> <p>The natural <span class="hlt">hydration</span> of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the <span class="hlt">hydrated</span> layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian <span class="hlt">hydration</span> dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring <span class="hlt">hydration</span> depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010935','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010935"><span>Obsidian <span class="hlt">hydration</span> dates glacial loading?</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Friedman, I.; Pierce, K.L.; Obradovich, J.D.; Long, W.D.</p> <p>1973-01-01</p> <p>Three different groups of <span class="hlt">hydration</span> rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming . The average thickness of the thickest (oldest) group of <span class="hlt">hydration</span> rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average <span class="hlt">hydration</span> rind thicknesses of 14.5 and 7.9 micrometers. These later two <span class="hlt">hydration</span> rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5532821','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5532821"><span>Interaction of copper with the surface of <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Franklin, M.L.; Morse, J.W.</p> <p>1981-12-01</p> <p>The interaction of Cu ions in solution with the surface of <span class="hlt">calcite</span> has been studied in a range of solutions from pure water to seawater. Observations of the uptake of Cu from solution onto <span class="hlt">calcite</span> indicates that the process is rapid and strong in both distilled water and seawater. In distilled water, Cu uptake is directly proportional to the concentration of Cu in solution; Cu/sub s/ = K/sub s/Cu/sub 1/. The average value for K/sub s/ is 3.5 +- 1.7. The Cu/sub s/ dependence on Cu/sub 1/ is linear over the entire Cu concentration range studied (0.1 to 200 ..mu..M). Results do not indicate the formation of a precipitate of either malachite or copper carbonate. A precipitate of the form Cu/sub x/Ca/sub 1-x/CO/sub 3/ may be deposited onto the <span class="hlt">calcite</span> surface in distilled water. The value of K/sub s/ in distilled water decreased sharply over the solid to solution ratio range of 0.1 to 2 g CaCO/sub 3/ 1/sup -1/. This was followed by a small change in K/sub s/ for solid to solution ratios in the range of 2 to 10 g CaCO/sub 3/ 1/sup -1/. In seawater, the uptake of Cu is also directly proportional to the concentration of Cu/sub 1/ up to a limiting value of approximately 13 ..mu..M. The average value for K/sub s/ in seawater, 0.24 +- 0.06 (Cu/sub 1/ less than or equal to 13 ..mu..M), is approximately an order of magnitude less than in distilled water. This is probably the result of smaller Cu/sub 1/ activity coefficients and increased site competition by other ions in seawater. Attempts to increase the Cu/sub 1/ concentration above 13 ..mu..M resulted in the additional Cu being deposited on the surface of the <span class="hlt">calcite</span>. A possible explanation for this behavior is the formation of a precipitate of malachite on the <span class="hlt">calcite</span> surface. The value of K/sub s/ decreased slightly with increasing solid to solution ratios in seawater.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20674541','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20674541"><span>Distribution of polycyclic aromatic hydrocarbons in <span class="hlt">lime</span> spray dryer ash</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ping Sun; Panuwat Taerakul; Linda K. Weavers; Harold W. Walker</p> <p>2005-10-01</p> <p>Four <span class="hlt">lime</span> spray dryer (LSD) ash samples were collected from a spreader stoker boiler and measured for their concentrations of 16 U.S. EPA specified polycyclic aromatic hydrocarbons (PAHs). Results showed that the total measured PAH concentration correlated with the organic carbon content of the LSD ash. Each LSD ash sample was then separated using a 140 mesh sieve into two fractions: a carbon-enriched fraction ({gt}140 mesh) and a <span class="hlt">lime</span>-enriched fraction ({lt}140 mesh). Unburned carbon was further separated from the carbon-enriched fraction with a lithiumheteropolytungstate (LST) solution. PAH measurements on these different fractions showed that unburned carbon had the highest PAH concentrations followed by the carbon-enriched fraction, indicating that PAHs were primarily associated with the carbonaceous material in LSD ash. However, detectable levels of PAHs were also found in the <span class="hlt">lime</span>-enriched fraction, suggesting that the fine spray of slaked <span class="hlt">lime</span> may sorb PAH compounds from the flue gas in the LSD process. 37 refs., 5 figs., 4 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5178867','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5178867"><span>Soda ash improves lead removal in <span class="hlt">lime</span> precipitation process</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hsu, D.Y.; Riddell, M.D.R.; Bonamico, B.</p> <p>1982-01-01</p> <p>Both laboratory-scale and plant-scale studies were conducted to evaluate the feasibility of using soda ash as a supplemental chemical in the existing <span class="hlt">lime</span> neutralization-sedimentation process. The purpose was to improve the efficiency of lead removal from a metal finishing wastewater by taking advantage of the lower solubility of lead carbonate. Plant-scale studies indicated that addition of soda ash at about 2 mg Na/sub 2/CO/sub 3/ per mg Pb and at a pH between 8 and 11.5 reduced lead content in the settled effluent consistently to less than 0.3 mg/l. This is considerably lower than the 0.5 mg/1 specified in the sewer use ordinance. After about one year's operation, this modified <span class="hlt">lime</span> neutralization-sedimentation process has been found to be more stable and reliable, and requires less attendance than the simple <span class="hlt">lime</span> process. The process can also now be operated at a lower pH (minimum: 7.0) with the addition of soda ash, which has resulted in a lower amount of sludge production, lower <span class="hlt">lime</span> usage and significantly lower manpower requirements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=185446&keyword=Plant+AND+cell+AND+walls&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90806269&CFTOKEN=56847592','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=185446&keyword=Plant+AND+cell+AND+walls&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=90806269&CFTOKEN=56847592"><span>EFFECTS OF <span class="hlt">LIME</span> (CAO) ON THE ENDOTOXIN LEVELS OF BIOSOLIDS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><span class="hlt">Lime</span> addition is a common practice for treating biosolids in order to meet EPA 503 requirements for land application. Since this treatment kills the majority of microorganisms, will it increase the level of endotoxins present in biosolids? And, if endotoxin levels are increased, ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23334836','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23334836"><span><span class="hlt">Lime</span> pretreatment and fermentation of enzymatically hydrolyzed sugarcane bagasse.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rabelo, Sarita C; Maciel Filho, Rubens; Costa, Aline C</p> <p>2013-03-01</p> <p>Sugarcane bagasse was subjected to <span class="hlt">lime</span> (calcium hydroxide) pretreatment and enzymatic hydrolysis for second-generation ethanol production. A central composite factorial design was performed to determine the best combination of pretreatment time, temperature, and <span class="hlt">lime</span> loading, as well as to evaluate the influence of enzymatic loadings on hydrolysis conversion. The influence of increasing solids loading in the pretreatment and enzymatic hydrolysis stages was also determined. The hydrolysate was fermented using Saccharomyces cerevisiae in batch and continuous mode. In the continuous fermentation, the hydrolysates were concentrated with molasses. <span class="hlt">Lime</span> pretreatment significantly increased the enzymatic digestibility of sugarcane bagasse without the need for prior particle size reduction. In the optimal pretreatment conditions (90 h, 90 °C, 0.47 glime/g bagasse) and industrially realistic conditions of hydrolysis (12.7 FPU/g of cellulase and 7.3 CBU/g of β-glucosidase), 139.6 kglignin/ton raw bagasse and 126.0 kg hemicellulose in the pretreatment liquor per ton raw bagasse were obtained. The hydrolysate from <span class="hlt">lime</span> pretreated sugarcane bagasse presented low amounts of inhibitors, leading to ethanol yield of 164.1 kgethanol/ton raw bagasse.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6455616','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6455616"><span>Method for <span class="hlt">lime</span> stabilization of wastewater treatment plant sludges</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wurtz, W.O.</p> <p>1981-12-22</p> <p>A method for the <span class="hlt">lime</span> stabilization of wastewater sludge, includes the steps of dewatering sludge so as to produce a sludge cake containing from about 10 to 60% by weight of dry solids and rapidly and intimately mixing and reacting the sludge cake with calcium oxide so as to produce stabilized sludge pellets. An apparatus for performing the process is also provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=ice+AND+cream&pg=6&id=ED173034','ERIC'); return false;" href="http://eric.ed.gov/?q=ice+AND+cream&pg=6&id=ED173034"><span>K'qizaghetnu Ht'ana (Stories from <span class="hlt">Lime</span> Village).</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Bobby, Pete; And Others</p> <p></p> <p>A cross section of Athabascan life as related by eight inhabitants of <span class="hlt">Lime</span> Village, Alaska, is given in this document. The short narratives are printed in English and in Dena'ina. Illustrations accompany the text. The stories tell of making eagle feather robes, birchbark or mooseskin boats, a raincoat from black bear intestines, and boots from…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/394372','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/394372"><span>Shock-wave properties of soda-<span class="hlt">lime</span> glass</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grady, D.E.; Chhabildas, L.C.</p> <p>1996-11-01</p> <p>Planar impact experiments and wave profile measurements provided single and double shock equation of state data to 30 GPa. Both compression wave wave profile structure and release wave data were used to infer time-dependent strength and equation of state properties for soda-<span class="hlt">lime</span> glass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JCrGr.345...61J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JCrGr.345...61J"><span><span class="hlt">Hydrate</span> formation and growth in pores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jung, Jong-Won; Santamarina, J. Carlos</p> <p>2012-04-01</p> <p>Gas <span class="hlt">hydrates</span> consist of guest gas molecules encaged in water cages. Methane <span class="hlt">hydrate</span> forms in marine and permafrost sediments. In this study, we use optical, mechanical and electrical measurements to monitor <span class="hlt">hydrate</span> formation and growth in small pores to better understand the <span class="hlt">hydrate</span> pore habit in <span class="hlt">hydrate</span>-bearing sediments. <span class="hlt">Hydrate</span> formation in capillary tubes exposes the complex and dynamic interactions between nucleation, gas diffusion and gas solubility. The observation of <span class="hlt">hydrate</span> growth in a droplet between transparent plates shows that the <span class="hlt">hydrate</span> shell does not grow homogeneously but advances in the form of lobes that invade the water phase; in fact, the <span class="hlt">hydrate</span> shell must be discontinuous and possibly cracked to justify the relatively fast growth rates observed in these experiments. Volume expansion during <span class="hlt">hydrate</span> formation causes water to flow out of menisci; expelled water either spreads on the surface of water-wet substrates and forms a thin <span class="hlt">hydrate</span> sheet, or remains next to menisci when substrates are oil-wet. <span class="hlt">Hydrate</span> formation is accompanied by ion exclusion, yet, there is an overall increase in electrical resistance during <span class="hlt">hydrate</span> formation. <span class="hlt">Hydrate</span> growth may become salt-limited in trapped water conditions; in this case, aqueous brine and gas CH4 may be separated by <span class="hlt">hydrate</span> and the three-phase system remains stable within the pore space of sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19569226','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19569226"><span>Crystallization of a polymorphic <span class="hlt">hydrate</span> system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tian, F; Qu, H; Louhi-Kultanen, M; Rantanen, J</p> <p>2010-02-01</p> <p>Nitrofurantoin can form two monohydrates, which have the same chemical composition and molar ratio of water, but differ in the crystal arrangements. The two monohydrates (<span class="hlt">hydrates</span> I and II) could be produced independently via evaporative crystallization, where supersaturation and solvent composition were both found to have an effect. <span class="hlt">Hydrate</span> I showed much slower crystallization than <span class="hlt">hydrate</span> II. During cooling crystallization, the nucleation and growth of <span class="hlt">hydrate</span> II was again dominant, consuming all supersaturation and leading to no <span class="hlt">hydrate</span> I formation. Seeding of <span class="hlt">hydrate</span> I during cooling crystallization was also applied, but the <span class="hlt">hydrate</span> I seeds were not able to initiate its nucleation rather than dissolving into crystallizing solution. Although solubility tests revealed that <span class="hlt">hydrate</span> II is more stable than <span class="hlt">hydrate</span> I due to its lower solubility (110 +/- 4 and 131 +/- 12 microg/mL for <span class="hlt">hydrates</span> II and I, respectively), this difference is rather small. Therefore, the small free energy difference between the two <span class="hlt">hydrates</span>, together with the slow crystallization of <span class="hlt">hydrate</span> I, both lead to a hindrance of <span class="hlt">hydrate</span> I formation. Furthermore, the crystal structure of <span class="hlt">hydrate</span> II demonstrated a higher H-bonding extent than <span class="hlt">hydrate</span> I, suggesting its more favorable crystallization. This is in good agreement with experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28063520','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28063520"><span>Zeta potential of artificial and natural <span class="hlt">calcite</span> in aqueous solution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Al Mahrouqi, Dawoud; Vinogradov, Jan; Jackson, Matthew D</p> <p>2017-02-01</p> <p>Despite the broad range of interest and applications, controls on <span class="hlt">calcite</span> surface charge in aqueous solution, especially at conditions relevant to natural systems, remain poorly understood. The primary data source to understand <span class="hlt">calcite</span> surface charge comprises measurements of zeta potential. Here we collate and review previous measurements of zeta potential on natural and artificial <span class="hlt">calcite</span> and carbonate as a resource for future studies, compare and contrast the results of these studies to determine key controls on zeta potential and where uncertainties remain, and report new measurements of zeta potential relevant to natural subsurface systems. The results show that the potential determining ions (PDIs) for the carbonate mineral surface are the lattice ions Ca(2+), Mg(2+) and CO3(2-). The zeta potential is controlled by the concentration-dependent adsorption of these ions within the Stern layer, primarily at the Outer Helmholtz Plane (OHP). Given this, the Iso-Electric Point (IEP) at which the zeta potential is zero should be expressed as pCa (or pMg). It should not be reported as pH, similar to most metal oxides. The pH does not directly control the zeta potential. Varying the pH whilst holding pCa constant yields constant zeta potential. The pH affects the zeta potential only by moderating the equilibrium pCa for a given CO2 partial pressure (pCO2). Experimental studies that appear to yield a systematic relationship between pH and zeta potential are most likely observing the relationship between pCa and zeta potential, with pCa responding to the change in pH. New data presented here show a consistent linear relationship between equilibrium pH and equilibrium pCa or pMg irrespective of sample used or solution ionic strength. The surface charge of <span class="hlt">calcite</span> is weakly dependent on pH, through protonation and deprotonation reactions that occur within a hydrolysis layer immediately adjacent to the mineral surface. The Point of Zero Charge (PZC) at which the surface</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTB...47.2651S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTB...47.2651S"><span>A Model for Dissolution of <span class="hlt">Lime</span> in Steelmaking Slags</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sarkar, Rahul; Roy, Ushasi; Ghosh, Dinabandhu</p> <p>2016-08-01</p> <p>In a previous study by Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015), a dynamic model of the LD steelmaking was developed. The prediction of the previous model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) for the bath (metal) composition matched well with the plant data (Cicutti et al. in Proceedings of 6th International Conference on Molten Slags, Fluxes and Salts, Stockholm City, 2000). However, with respect to the slag composition, the prediction was not satisfactory. The current study aims to improve upon the previous model Sarkar et al. (Metall. Mater. Trans. B 46B:961 2015) by incorporating a <span class="hlt">lime</span> dissolution submodel into the earlier one. From the industrial point of view, the understanding of the <span class="hlt">lime</span> dissolution kinetics is important to meet the ever-increasing demand of producing low-P steel at a low basicity. In the current study, three-step kinetics for the <span class="hlt">lime</span> dissolution is hypothesized on the assumption that a solid layer of 2CaO·SiO2 should form around the unreacted core of the <span class="hlt">lime</span>. From the available experimental data, it seems improbable that the observed kinetics should be controlled singly by any one kinetic step. Accordingly, a general, mixed control model has been proposed to calculate the dissolution rate of the <span class="hlt">lime</span> under varying slag compositions and temperatures. First, the rate equation for each of the three rate-controlling steps has been derived, for three different <span class="hlt">lime</span> geometries. Next, the rate equation for the mixed control kinetics has been derived and solved to find the dissolution rate. The model predictions have been validated by means of the experimental data available in the literature. In addition, the effects of the process conditions on the dissolution rate have been studied, and compared with the experimental results wherever possible. Incorporation of this submodel into the earlier global model (Sarkar et al. in Metall. Mater. Trans. B 46B:961 2015) enables the prediction of the <span class="hlt">lime</span> dissolution rate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4567929','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4567929"><span>Airway <span class="hlt">Hydration</span> and COPD</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ghosh, Arunava; Boucher, R.C.; Tarran, Robert</p> <p>2015-01-01</p> <p>Chronic obstructive pulmonary disease (COPD) is one of the prevalent causes of worldwide mortality and encompasses two major clinical phenotypes, i.e., chronic bronchitis (CB) and emphysema. The most common cause of COPD is chronic tobacco inhalation. Research focused on the chronic bronchitic phenotype of COPD has identified several pathological processes that drive disease initiation and progression. For example, the lung’s mucociliary clearance (MCC) system performs the critical task of clearing inhaled pathogens and toxic materials from the lung. MCC efficiency is dependent on: (i) the ability of apical plasma membrane ion channels such as the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na+ channel (ENaC) to maintain airway <span class="hlt">hydration</span>; (ii) ciliary beating; and, (iii) appropriate rates of mucin secretion. Each of these components is impaired in CB and likely contributes to the mucus stasis/accumulation seen in CB patients. This review highlights the cellular components responsible for maintaining MCC and how this process is disrupted following tobacco exposure and with CB. We shall also discuss existing therapeutic strategies for the treatment of chronic bronchitis and how components of the MCC can be used as biomarkers for the evaluation of tobacco or tobacco-like-product exposure. PMID:26068443</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21033077','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21033077"><span>New waste based clinkers: Belite and <span class="hlt">lime</span> formulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Raupp-Pereira, Fabiano; Ball, Richard James Rocha, Joao; Labrincha, Joao A.; Allen, Geoffrey C.</p> <p>2008-04-15</p> <p>This work describes the formulation of new belite-based (CR2) and <span class="hlt">lime</span>-based (CR3) cementitious materials derived from industrial wastes, such as sludges (generated in the Al-anodising and surface coating industrial processes, potable water filtration/cleaning operations and in marble sawing processes) and foundry sand. Powder mixtures were prepared and fired at different temperatures. For comparison, similar formulations were prepared with pre-treated and commercially available natural raw materials and processed in similar conditions. The thermal process was followed by differential scanning calorimetry (DSC) and high-temperature powder X-ray diffraction (HT-XRD) studies. The CR2 clinker was found to contain belite as the main cementitious phase, the main polymorph being identified by NMR. The CR3 clinker contained common cementitious phases, such as C{sub 3}A and C{sub 3}S, but free <span class="hlt">lime</span> and calcium aluminium oxide sulphates were also identified by high temperature XRD and NMR. Then the corresponding cement was prepared and the evolution of the mechanical strength with time was evaluated. The <span class="hlt">lime</span>-based cement obtained from wastes shows a stronger hardening character than the standard material, which tends to show dusting phenomena due to the presence of a reasonable amount of free <span class="hlt">lime</span> (as the result of its expansive reaction with ambient moisture). Some fluxing impurities (e.g. alkalis) present in the waste materials improve the overall reactivity of the mixture and induces the combination of the <span class="hlt">lime</span> in CR3. Raman, XPS and FIB techniques were used to fully characterise the aged cements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22119052','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22119052"><span>Evaluation of a <span class="hlt">lime</span>-mediated sewage sludge stabilisation process. Product characterisation and technological validation for its use in the cement industry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rodríguez, N Husillos; Granados, R J; Blanco-Varela, M T; Cortina, J L; Martínez-Ramírez, S; Marsal, M; Guillem, M; Puig, J; Fos, C; Larrotcha, E; Flores, J</p> <p>2012-03-01</p> <p>This paper describes an industrial process for stabilising sewage sludge (SS) with <span class="hlt">lime</span> and evaluates the viability of the stabilised product, denominated Neutral, as a raw material for the cement industry. <span class="hlt">Lime</span> not only stabilised the sludge, raised the temperature of the mix to 80-100°C, furthering water evaporation, portlandite formation and the partial oxidation of the organic matter present in the sludge. Process mass and energy balances were determined. Neutral, a white powder consisting of portlandite (49.8%), <span class="hlt">calcite</span> (16.6%), inorganic oxides (13.4%) and organic matter and moisture (20.2%), proved to be technologically apt for inclusion as a component in cement raw mixes. In this study, it was used instead of limestone in raw mixes clinkerised at 1400, 1450 and 1500°C. These raw meals exhibited greater reactivity at high temperatures than the limestone product and their calcination at 1500°C yielded clinker containing over 75% calcium silicates, the key phases in Portland clinker. Finally, the two types of raw meal (Neutral and limestone) were observed to exhibit similar mineralogy and crystal size and distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RJPCA..90.2377S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RJPCA..90.2377S"><span>Tetrahydrofuran <span class="hlt">hydrate</span> decomposition characteristics in porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Yongchen; Wang, Pengfei; Wang, Shenglong; Zhao, Jiafei; Yang, Mingjun</p> <p>2016-12-01</p> <p>Many tetrahydrofuran (THF) <span class="hlt">hydrate</span> properties are similar to those of gas <span class="hlt">hydrates</span>. In the present work THF <span class="hlt">hydrate</span> dissociation in four types of porous media is studied. THF solution was cooled to 275.15 K with formation of the <span class="hlt">hydrate</span> under ambient pressure, and then it dissociated under ambient conditions. THF <span class="hlt">hydrate</span> dissociation experiments in each porous medium were conducted three times. Magnetic resonance imaging (MRI) was used to obtain images. Decomposition time, THF <span class="hlt">hydrate</span> saturation and MRI mean intensity (MI) were measured and analyzed. The experimental results showed that the <span class="hlt">hydrate</span> decomposition time in BZ-4 and BZ-3 was similar and longer than that in BZ-02. In each dissociation process, the <span class="hlt">hydrate</span> decomposition time of the second and third cycles was shorter than that of the first cycle in BZ-4, BZ-3, and BZ-02. The relationship between THF <span class="hlt">hydrate</span> saturation and time is almost linear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024086','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024086"><span>Energy resource potential of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, T.S.</p> <p>2002-01-01</p> <p>The discovery of large gas <span class="hlt">hydrate</span> accumulations in terrestrial permafrost regions of the Arctic and beneath the sea along the outer continental margins of the world's oceans has heightened interest in gas <span class="hlt">hydrates</span> as a possible energy resource. However, significant to potentially insurmountable technical issues must be resolved before gas <span class="hlt">hydrates</span> can be considered a viable option for affordable supplies of natural gas. The combined information from Arctic gas <span class="hlt">hydrate</span> studies shows that, in permafrost regions, gas <span class="hlt">hydrates</span> may exist at subsurface depths ranging from about 130 to 2000 m. The presence of gas <span class="hlt">hydrates</span> in offshore continental margins has been inferred mainly from anomalous seismic reflectors, known as bottom-simulating reflectors, that have been mapped at depths below the sea floor ranging from about 100 to 1100 m. Current estimates of the amount of gas in the world's marine and permafrost gas <span class="hlt">hydrate</span> accumulations are in rough accord at about 20,000 trillion m3. Disagreements over fundamental issues such as the volume of gas stored within delineated gas <span class="hlt">hydrate</span> accumulations and the concentration of gas <span class="hlt">hydrates</span> within <span class="hlt">hydrate</span>-bearing strata have demonstrated that we know little about gas <span class="hlt">hydrates</span>. Recently, however, several countries, including Japan, India, and the United States, have launched ambitious national projects to further examine the resource potential of gas <span class="hlt">hydrates</span>. These projects may help answer key questions dealing with the properties of gas <span class="hlt">hydrate</span> reservoirs, the design of production systems, and, most important, the costs and economics of gas <span class="hlt">hydrate</span> production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011GeCoA..75.3956D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011GeCoA..75.3956D"><span>Oxygen isotopes in <span class="hlt">calcite</span> grown under cave-analogue conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Day, C. C.; Henderson, G. M.</p> <p>2011-07-01</p> <p>Speleothem oxygen isotopes and growth rates are valuable proxies for reconstructing climate history. There is debate, however, about the conditions that allow speleothems to grow in oxygen isotope equilibrium, and about the correct equilibrium fractionation factors. We report results from a series of carbonate growth experiments in karst-analogue conditions in the laboratory. The setup closely mimics natural processes (e.g. precipitation driven by CO 2-degassing, low ionic strength solution, thin solution film) but with a tight control on growth conditions (temperature, pCO 2, drip rate, <span class="hlt">calcite</span> saturation index and the composition of the initial solution). <span class="hlt">Calcite</span> is dissolved in water in a 20,000 ppmV pCO 2 environment. This solution is dripped onto glass plates (coated with seed-carbonate) in a lower pCO 2 environment (<2500 ppmV), where degassing leads to <span class="hlt">calcite</span> growth. Experiments were performed at 7, 15, 25 and 35 °C. At each temperature, <span class="hlt">calcite</span> was grown at three drip rates (2, 6 and 10 drips per minute) on separate plates. The mass of <span class="hlt">calcite</span> grown in these experiments varies with temperature ( T in K) and drip rate ( d_ r in drips min -1) according to the relationship daily growth mass = 1.254 + 1.478 ∗ 10 -9 ∗ e0.0679 T + ( e0.00248 T - 2) ∗ (-0.779 d_ r2 + 10.05 d_ r + 11.69). This relationship indicates a substantial increase of growth mass with temperature, a smaller influence of drip rate on growth mass at low temperature and a non-linear relationship between drip rate and growth mass at higher temperatures. Low temperature, fast dripping conditions are found to be the most favourable for reducing effects associated with evaporation and rapid depletion of the dissolved inorganic carbon reservoir (rapid DIC-depletion). The impact of evaporation can be large so caves with high relative humidity are also preferable for palaeoclimate reconstruction. Even allowing for the maximum offsets that may have been induced by evaporation and rapid DIC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70010877','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70010877"><span>The sensitized luminescence of manganese-activated <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Schulman, J.H.; Evans, L.W.; Ginther, R.J.; Murata, K.J.</p> <p>1947-01-01</p> <p>Synthetic manganese-activated <span class="hlt">calcites</span> are shown to be practically inert to ultraviolet excitation in the range 2000-3500A, while they are luminescent under cathode-ray excitation. The incorporation of small amounts of an auxiliary impurity along with the manganese produces the strong response to ultraviolet radiation hitherto ascribed to CaCO3:Mn itself. Three such impurities have been studied: lead, thallium, and cerium. The first two induce excitation in the neighborhood of the mercury resonance line, while the cerium introduces a response principally to longer wave ultraviolet. The strong response to 2537A excitation shown by some natural <span class="hlt">calcites</span> is likewise found to be due to the presence of lead along with the manganese, rather than to the manganese alone. The data do not warrant ascribing the longer wave-length ultraviolet-excited luminescence of all natural <span class="hlt">calcites</span> to the action of an auxiliary impurity. The essential identity of the cathode-ray excited luminescence spectra of CaCO 3:Mn, CaCO3: (Pb+Mn), CaCO3:(Tl+Mn), and CaCO3:(Ce+Mn) with the 2537A-excited spectra of the latter three is evidence that the luminescent center in all cases is the manganese ion or the MnO6 group. It is shown that a "cascade" mechanism for the action of the auxiliary impurities, lead, thallium, and cerium, is incorrect; and that the phenomenon must be considered as a case of sensitized luminescence. Owing to the nature of cathode-ray excitation, the manganese activator can be excited by this agent even in the absence of a second impurity. For optical excitation, however, an absorption band for the ultraviolet must be established by building into the CaCO3:Mn a second impurity or "sensitizer.".</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4105460','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4105460"><span>Principles of <span class="hlt">Calcite</span> Dissolution in Human and Artificial Otoconia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Walther, Leif Erik; Blödow, Alexander; Buder, Jana; Kniep, Rüdiger</p> <p>2014-01-01</p> <p>Human otoconia provide mechanical stimuli to deflect hair cells of the vestibular sensory epithelium for purposes of detecting linear acceleration and head tilts. During lifetime, the volume and number of otoconia are gradually reduced. In a process of degeneration morphological changes occur. Structural changes in human otoconia are assumed to cause vertigo and balance disorders such as benign paroxysmal positional vertigo (BPPV). The aim of this study was to investigate the main principles of morphological changes in human otoconia in dissolution experiments by exposure to hydrochloric acid, EDTA, demineralized water and completely purified water respectively. For comparison reasons artificial (biomimetic) otoconia (<span class="hlt">calcite</span> gelatin nanocomposits) and natural <span class="hlt">calcite</span> were used. Morphological changes were detected in time steps by the use of environmental scanning electron microscopy (ESEM). Under in vitro conditions three main dissolution mechanisms were identified as causing characteristic morphological changes of the specimen under consideration: pH drops in the acidic range, complex formation with calcium ions and changes of ion concentrations in the vicinity of otoconia. Shifts in pH cause a more uniform reduction of otoconia size (isotropic dissolution) whereas complexation reactions and changes of the ionic concentrations within the surrounding medium bring about preferred attacks at specific areas (anisotropic dissolution) of human and artificial otoconia. Owing to successive reduction of material, all the dissolution mechanisms finally produce fragments and remnants of otoconia. It can be assumed that the organic component of otoconia is not significantly attacked under the given conditions. Artificial otoconia serve as a suitable model system mimicking chemical attacks on biogenic specimens. The underlying principles of <span class="hlt">calcite</span> dissolution under in vitro conditions may play a role in otoconia degeneration processes such as BPPV. PMID:25048115</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6568348','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6568348"><span><span class="hlt">Calcite</span> dissolution: an in situ study in the Panama Basin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Thunell, R.C.; Keir, R.S.; Honjo, S.</p> <p>1981-05-08</p> <p>The results of an in situ study of <span class="hlt">calcite</span> dissolution in the Panama Basin indicate that the rate of dissolution in the water column increases suddenly below a water depth of about 2800 meters. This coincides with the depth at which the calcium carbonate content of surface sediments begins to decrease rapidly or the sedimentary lysocline. Since this level of increased dissolution both in the water column and on the sea floor does not appear to be related to the transition from supersaturation to undersaturation with respect to carbonate, there may be a kinetic origin for the lysocline in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17739398','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17739398"><span><span class="hlt">Calcite</span> Dissolution: An in situ Study in the Panama Basin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thunell, R C; Keir, R S; Honjo, S</p> <p>1981-05-08</p> <p>The results of an in situ study of <span class="hlt">calcite</span> dissolution in the Panama Basin indicate that the rate of dissolution in the water column increases suddenly below a water depth of about 2800 meters. This coincides with the depth at which the calcium carbonate content of surface sediments begins to decrease rapidly or the sedimentary lysocline. Since this level of increased dissolution both in the water column and on the sea floor does not appear to be related to the transition from supersaturation to undersaturation with respect to carbonate, there may be a kinetic origin for the lysocline in this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007EPJST.141..223Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007EPJST.141..223Y"><span><span class="hlt">Hydration</span> water in dynamics of a <span class="hlt">hydrated</span> beta-lactoglobulin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoshida, K.; Yamaguchi, T.; Bellissent-Funel, M.-C.; Longeville, S.</p> <p>2007-02-01</p> <p>Incoherent spin-echo signals of a <span class="hlt">hydrated</span> β-lactoglobulin protein were investigated, at 275 and 293 K. The intermediate scattering functions I(Q,t) were divided in two contributions from surface water and protein, respectively. On one hand, the dynamics of the surface water follows a KWW stretched exponential function (the exponent is ~0.5), on the other hand, that of the protein follows a single exponential. The present results are consistent with our previous results of <span class="hlt">hydrated</span> C-phycocyanin combining elastic and quasielastic neutron scattering and by molecular dynamics simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000Geo....28..931M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000Geo....28..931M"><span>Unusual <span class="hlt">calcite</span> stromatolites and pisoids from a landfill leachate collection system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maliva, Robert G.; Missimer, Thomas M.; Leo, Kevin C.; Statom, Richard A.; Dupraz, Christophe; Lynn, Matthew; Dickson, J. A. D.</p> <p>2000-10-01</p> <p>Low-magnesium <span class="hlt">calcite</span> stromatolites and pisoids were found to have precipitated within the leachate collection system piping of a Palm Beach County, Florida, landfill. The stromatolites and pisoids formed in an aphotic and anoxic environment that was at times greatly supersaturated with <span class="hlt">calcite</span>. The stromatolites are composed of branching cylindrical bundles of concentrically laminated radial fibrous crystals. The pisoids consist of concentric layers of radial fibrous and microcrystalline <span class="hlt">calcite</span>. Bacteria, likely sulfate reducing, appear to have acted as catalysts for <span class="hlt">calcite</span> crystal nucleation, and thus the formation of the stromatolites and pisoids. The leachate system stromatolites provide a recent example of stromatolites that formed largely by cement precipitation. By acting as catalysts for <span class="hlt">calcite</span> nucleation, bacteria may cause more rapid cementation than would have occurred under purely abiotic conditions. Rapid <span class="hlt">calcite</span> precipitation catalyzed by bacteria has interfered with the operation of the Palm Beach County landfill leachate collection by obstructing pipes and may be an unrecognized problem at other landfill sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6824342','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6824342"><span>Well log evaluation of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S.</p> <p>1992-10-01</p> <p>Gas <span class="hlt">hydrates</span> are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas <span class="hlt">hydrates</span> are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane <span class="hlt">hydrates</span> appear to be the most common in nature. The amount of methane sequestered in gas <span class="hlt">hydrates</span> is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the <span class="hlt">hydrate</span> reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas <span class="hlt">hydrates</span> also represent a significant drilling and production hazard. A fundamental question linking gas <span class="hlt">hydrate</span> resource and hazard issues is: What is the volume of gas <span class="hlt">hydrates</span> and included gas within a given gas <span class="hlt">hydrate</span> occurrence Most published gas <span class="hlt">hydrate</span> resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas <span class="hlt">hydrates</span> are dependent on a number of reservoir parameters, including the areal extent ofthe gas-<span class="hlt">hydrate</span> occurrence, reservoir thickness, <span class="hlt">hydrate</span> number, reservoir porosity, and the degree of gas-<span class="hlt">hydrate</span> saturation. Two of the most difficult reservoir parameters to determine are porosity and degreeof gas <span class="hlt">hydrate</span> saturation. Well logs often serve as a source of porosity and hydrocarbon saturation data; however, well-log calculations within gas-<span class="hlt">hydrate</span>-bearing intervals are subject to error. The primary reason for this difficulty is the lack of quantitative laboratory and field studies. The primary purpose of this paper is to review the response of well logs to the presence of gas <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10142315','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10142315"><span>Well log evaluation of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S.</p> <p>1992-10-01</p> <p>Gas <span class="hlt">hydrates</span> are crystalline substances composed of water and gas, in which a solid-water-lattice accommodates gas molecules in a cage-like structure. Gas <span class="hlt">hydrates</span> are globally widespread in permafrost regions and beneath the sea in sediment of outer continental margins. While methane, propane, and other gases can be included in the clathrate structure, methane <span class="hlt">hydrates</span> appear to be the most common in nature. The amount of methane sequestered in gas <span class="hlt">hydrates</span> is probably enormous, but estimates are speculative and range over three orders of magnitude from about 100,000 to 270,000,000 trillion cubic feet. The amount of gas in the <span class="hlt">hydrate</span> reservoirs of the world greedy exceeds the volume of known conventional gas reserves. Gas <span class="hlt">hydrates</span> also represent a significant drilling and production hazard. A fundamental question linking gas <span class="hlt">hydrate</span> resource and hazard issues is: What is the volume of gas <span class="hlt">hydrates</span> and included gas within a given gas <span class="hlt">hydrate</span> occurrence? Most published gas <span class="hlt">hydrate</span> resource estimates have, of necessity, been made by broad extrapolation of only general knowledge of local geologic conditions. Gas volumes that may be attributed to gas <span class="hlt">hydrates</span> are dependent on a number of reservoir parameters, including the areal extent ofthe gas-<span class="hlt">hydrate</span> occurrence, reservoir thickness, <span class="hlt">hydrate</span> number, reservoir porosity, and the degree of gas-<span class="hlt">hydrate</span> saturation. Two of the most difficult reservoir parameters to determine are porosity and degreeof gas <span class="hlt">hydrate</span> saturation. Well logs often serve as a source of porosity and hydrocarbon saturation data; however, well-log calculations within gas-<span class="hlt">hydrate</span>-bearing intervals are subject to error. The primary reason for this difficulty is the lack of quantitative laboratory and field studies. The primary purpose of this paper is to review the response of well logs to the presence of gas <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010GeCoA..74.6751H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010GeCoA..74.6751H"><span>Application of <span class="hlt">calcite</span> Mg partitioning functions to the reconstruction of paleocean Mg/Ca</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasiuk, Franciszek J.; Lohmann, Kyger C.</p> <p>2010-12-01</p> <p><span class="hlt">Calcite</span> Mg/Ca is usually assumed to vary linearly with solution Mg/Ca, that a constant partition coefficient describes the relationship between these two ratios. Numerous published empirical datasets suggests that this relationship is better described by a power function. We provide a compilation of these literature data for biotic and abiotic <span class="hlt">calcite</span> in the form of <span class="hlt">Calcite</span> Mg/Ca = F(Solution Mg/Ca) H, where F and H are empirically determined fitting parameters describing the slope and deviation from linearity, respectively, of the function. This is equivalent to Freundlich sorption behavior controlling Mg incorporation in <span class="hlt">calcite</span>. Using a power function, instead of a partition coefficient, lowers Phanerozoic seawater Mg/Ca estimates based on echinoderm skeletal material by, on average, 0.5 mol/mol from previous estimates. These functions can also be used to model the primary skeletal <span class="hlt">calcite</span> Mg/Ca of numerous <span class="hlt">calcite</span> phases through geologic time. Such modeling suggests that the Mg/Ca of all <span class="hlt">calcite</span> precipitated from seawater has varied through the Phanerozoic in response to changing seawater Mg/Ca and that the overall range in Mg/Ca measured among various <span class="hlt">calcite</span> phases would be greatest when seawater Mg/Ca was also high (e.g., "aragonite seas") and lowest when seawater Mg/Ca was low (e.g., "<span class="hlt">calcite</span> seas"). It follows that, during times of "<span class="hlt">calcite</span> seas" when the seawater Mg/Ca is presumed to have been lower, deposition of <span class="hlt">calcite</span> with low Mg contents would have resulted in a depressed drive for diagenetic stabilization of shelfal carbonate and, in turn, lead to greater preservation of crystal and skeletal microfabrics and primary chemistries in biotic and abiotic <span class="hlt">calcites</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029040','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029040"><span>The ubiquitous nature of accessory <span class="hlt">calcite</span> in granitoid rocks: Implications for weathering, solute evolution, and petrogenesis</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>White, A.F.; Schulz, M.S.; Lowenstern, J. B.; Vivit, D.V.; Bullen, T.D.</p> <p>2005-01-01</p> <p><span class="hlt">Calcite</span> is frequently cited as a source of excess Ca, Sr and alkalinity in solutes discharging from silicate terrains yet, no previous effort has been made to assess systematically the overall abundance, composition and petrogenesis of accessory <span class="hlt">calcite</span> in granitoid rocks. This study addresses this issue by analyzing a worldwide distribution of more than 100 granitoid rocks. <span class="hlt">Calcite</span> is found to be universally present in a concentration range between 0.028 to 18.8 g kg-1 (mean = 2.52 g kg-1). <span class="hlt">Calcite</span> occurrences include small to large isolated anhedral grains, fracture and cavity infillings, and sericitized cores of plagioclase. No correlation exists between the amount of <span class="hlt">calcite</span> present and major rock oxide compositions, including CaO. Ion microprobe analyses of in situ <span class="hlt">calcite</span> grains indicate relatively low Sr (120 to 660 ppm), negligible Rb and 87Sr/86Sr ratios equal to or higher than those of coexisting plagioclase. Solutes, including Ca and alkalinity produced by batch leaching of the granitoid rocks (5% CO2 in DI water for 75 d at 25??C), are dominated by the dissolution of <span class="hlt">calcite</span> relative to silicate minerals. The correlation of these parameters with higher <span class="hlt">calcite</span> concentrations decreases as leachates approach thermodynamic saturation. In longer term column experiments (1.5 yr), reactive <span class="hlt">calcite</span> becomes exhausted, solute Ca and Sr become controlled by feldspar dissolution and 87Sr/ 86Sr by biotite oxidation. Some accessory <span class="hlt">calcite</span> in granitoid rocks is related to intrusion into carbonate wall rock or produced by later hydrothermal alteration. However, the ubiquitous occurrence of <span class="hlt">calcite</span> also suggests formation during late stage (subsolidus) magmatic processes. This conclusion is supported by petrographic observations and 87Sr/86Sr analyses. A review of thermodynamic data indicates that at moderate pressures and reasonable CO2 fugacities, <span class="hlt">calcite</span> is a stable phase at temperatures of 400 to 700??C. Copyright ?? 2005 Elsevier Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA452109','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA452109"><span>A Laboratory Study Investigating the Feasibility of Applying <span class="hlt">Calcite</span>-Type Coatings to Segregated Ballast Tanks</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1981-08-01</p> <p>A LABORATORY STUDY INVESTIGATIING THE FEASIBILITY OF APPLYING <span class="hlt">CALCITE</span> -TYPE COATINGS TO SEGREGATED BALLAST TANKS AUGUST, 1981 Prepared by: Ocean City...Laboratory Study Investigating The Feasibility of Applying <span class="hlt">Calcite</span> -Type Coatings to Segregated Ballast Tanks 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c...Executive Summary List of Figures I. Conclusions II. Introduction III. Background-The Development and Use of <span class="hlt">Calcite</span> -Type Coatings IV. Experimental</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA451914','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA451914"><span>An Investigation of Possible Ways to Enhance the Deposition of <span class="hlt">Calcite</span>-Type Coatings</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1984-01-01</p> <p>AN INVESTIGATION OF POSSIBLE WAYS TO ENHANCE THE DEPOSITION OF <span class="hlt">CALCITE</span> -TYPE COATINGS JANUARY 1984 Prepared by: OCEAN CITY RESEARCH CORP. in...Enhance The Deposition of <span class="hlt">Calcite</span> -Type Coatings 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...City, New Jersey under the direction of Mr. The research study continued of applying <span class="hlt">calcite</span> -type coatings George A. Gehring, Jr. an to investigation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17807291','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17807291"><span><span class="hlt">Calcite</span>: rates of dissolution in a vertical profile in the central pacific.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peterson, M N</p> <p>1966-12-23</p> <p>Rate of dissoluton of calcium carbonate (<span class="hlt">calcite</span>) was determined for a vertical profile 5000 mizeters deep in the central Pacific by measuring the loss of weight of optical <span class="hlt">calcite</span> spheres arrayed on a mooring. Waters of the Pacific are undersaturated in all but the upper several hundred meters. A sharp increase in the rate of dissolution occurs at a depth of about 3700 meters, which corresponds closely to the depth below which <span class="hlt">calcite</span> hias been dissolved from the sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5588837','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5588837"><span>Dissociation heat transfer characteristics of methane <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kamath, V.A.; Holder, G.D.</p> <p>1987-02-01</p> <p>Knowledge of the interfacial heat transfer phenomenon during the dissociation of gas <span class="hlt">hydrates</span> is essential in modeling the <span class="hlt">hydrate</span> dissociation process. Such knowledge has applications in natural gas processing, storage, or transportation; in the drilling and recovery of oil and gas in the presence of gas <span class="hlt">hydrates</span>; in the desalination of sea water; and in the production of natural gas from <span class="hlt">hydrate</span> reservoirs. The process of <span class="hlt">hydrate</span> dissociation is a unique phenomenon in which gas and water are simultaneously produced at the dissociated <span class="hlt">hydrate</span> surface and play an important role in the mechanism of heat transfer to <span class="hlt">hydrates</span>. An earlier study of propane <span class="hlt">hydrate</span> dissociation showed that <span class="hlt">hydrate</span> dissociation is a heat-transfer-limited process and somewhat similar to the nucleate boiling of liquids. In the present study, heat transfer limitations for methane <span class="hlt">hydrate</span> dissociation were studied for two reasons. First, a comparison of the results of this study with propane <span class="hlt">hydrate</span> was desired. Second, the effect of <span class="hlt">hydrate</span> structure and gas molecule type on the rate of heat transfer during <span class="hlt">hydrate</span> dissociation was sought.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/566315','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/566315"><span>Heavy metals in wastewater: Modelling the hydroxide precipitation of copper(II) from wastewater using <span class="hlt">lime</span> as the precipitant</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baltpurvins, K.A.; Burns, R.C.; Lawrance, G.A.</p> <p>1996-12-31</p> <p>The effect of effluent composition (Cl{sup {minus}}, SO{sub 4}{sup 2{minus}} or CO{sub 3}{sup 2{minus}}) on the efficiency of the hydroxide precipitation of Cu(II) modelling <span class="hlt">lime</span> (CaO) as the precipitant has been predicted using the solubility domain approach and has been experimentally validated. Solubility domains were based on the phases that were found to be solubility-limiting for systems representing potential effluent chemical composition limits. The generated solubility domains generally encompassed the experimentally observed solubilities, thereby providing effluent treatment quality assurance ranges for the hydroxide precipitation process. The presence of gypsum (CaSO{sub 4{center_dot}}2H{sub 2}O) and <span class="hlt">calcite</span> (CaCO{sub 3}) as secondary precipitates had little effect on the observed residual Cu(II) solubilities, with Cu(II) mobility being governed by the least-soluble kinetically precipitated (rather than thermodynamically favored) phase in the system under study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..323...38M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..323...38M"><span><span class="hlt">Calcite</span> sealing in a fractured geothermal reservoir: Insights from combined EBSD and chemistry mapping</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McNamara, David D.; Lister, Aaron; Prior, Dave J.</p> <p>2016-09-01</p> <p>Fractures play an important role as fluid flow pathways in geothermal resources hosted in indurated greywacke basement of the Taupo Volcanic Zone, New Zealand, including the Kawerau Geothermal Field. Over time, the permeability of such geothermal reservoirs can be degraded by fracture sealing as minerals deposit out of transported geothermal fluids. <span class="hlt">Calcite</span> is one such fracture sealing mineral. This study, for the first time, utilises combined data from electron backscatter diffraction and chemical mapping to characterise <span class="hlt">calcite</span> vein fill morphologies, and gain insight into the mechanisms of <span class="hlt">calcite</span> fracture sealing in the Kawerau Geothermal Field. Two <span class="hlt">calcite</span> sealing mechanisms are identified 1) asymmetrical syntaxial growth of <span class="hlt">calcite</span>, inferred by the presence of single, twinned, <span class="hlt">calcite</span> crystals spanning the entire fracture width, and 2) 3D, interlocking growth of bladed vein <span class="hlt">calcite</span> into free space as determined from chemical and crystallographic orientation mapping. This study also identifies other potential uses of combined EBSD and chemical mapping to understand geothermal field evolution including, potentially informing on levels of fluid supersaturation from the study of <span class="hlt">calcite</span> lattice distortion, and providing information on a reservoir's history of stress, strain, and deformation through investigation of <span class="hlt">calcite</span> crystal deformation and twinning patterns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JChPh.145h4702F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JChPh.145h4702F"><span>Anisotropic parallel self-diffusion coefficients near the <span class="hlt">calcite</span> surface: A molecular dynamics study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franco, Luís F. M.; Castier, Marcelo; Economou, Ioannis G.</p> <p>2016-08-01</p> <p>Applying classical molecular dynamics simulations, we calculate the parallel self-diffusion coefficients of different fluids (methane, nitrogen, and carbon dioxide) confined between two { 10 1 ¯ 4 } <span class="hlt">calcite</span> crystal planes. We have observed that the molecules close to the <span class="hlt">calcite</span> surface diffuse differently in distinct directions. This anisotropic behavior of the self-diffusion coefficient is investigated for different temperatures and pore sizes. The ion arrangement in the <span class="hlt">calcite</span> crystal and the strong interactions between the fluid particles and the <span class="hlt">calcite</span> surface may explain the anisotropy in this transport property.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27586936','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27586936"><span>Anisotropic parallel self-diffusion coefficients near the <span class="hlt">calcite</span> surface: A molecular dynamics study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Franco, Luís F M; Castier, Marcelo; Economou, Ioannis G</p> <p>2016-08-28</p> <p>Applying classical molecular dynamics simulations, we calculate the parallel self-diffusion coefficients of different fluids (methane, nitrogen, and carbon dioxide) confined between two {101̄4} <span class="hlt">calcite</span> crystal planes. We have observed that the molecules close to the <span class="hlt">calcite</span> surface diffuse differently in distinct directions. This anisotropic behavior of the self-diffusion coefficient is investigated for different temperatures and pore sizes. The ion arrangement in the <span class="hlt">calcite</span> crystal and the strong interactions between the fluid particles and the <span class="hlt">calcite</span> surface may explain the anisotropy in this transport property.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1050328','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1050328"><span>LOW VELOCITY SHPERE IMPACT OF SODA <span class="hlt">LIME</span> SILICATE GLASS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Morrissey, Timothy G; Fox, Ethan E; Wereszczak, Andrew A; Vuono, Daniel J</p> <p>2012-01-01</p> <p>This report summarizes TARDEC-sponsored work at Oak Ridge National Laboratory (ORNL) during the FY11 involving low velocity ( 30 m/s or 65 mph) ball impact testing of Starphire soda <span class="hlt">lime</span> silicate glass. The intent was to better understand low velocity impact response in the Starphire for sphere densities that bracketed that of rock. Five sphere materials were used: borosilicate glass, soda-<span class="hlt">lime</span> silicate glass, steel, silicon nitride, and alumina. A gas gun was fabricated to produce controlled velocity delivery of the spheres against Starphire tile targets. Minimum impact velocities to initiate fracture in the Starphire were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the any of the five sphere-Starphire-target combinations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/884762','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/884762"><span>Acceleration of <span class="hlt">calcite</span> kinetics by abalone nacre proteins</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fu, G; Qiu, S R; Orme, C A; Morse, D E; De Yoreo, J J</p> <p>2005-06-09</p> <p>The fascinating shapes and hierarchical designs of biomineralized structures have long been an inspiration to materials scientists because of the potential they suggest for biomolecular control over synthesis of crystalline materials. One prevailing view is that mineral-associated macromolecules are responsible for initiating and stabilizing non-equilibrium crystal polymorphs and morphologies through interactions between anionic moieties and cations in solution or at mineral surfaces. Indeed, numerous studies have demonstrated that bio-organic additives can dramatically alter crystal shapes and growth-rates in vitro. However, previous molecular-scale studies revealing mechanisms of growth modification focused on small molecules such as amino acids or peptides and always observed growth inhibition. In contrast, studies using full proteins were non-quantitative and underlying sources of growth modification were ill-defined. Here we investigate interactions between proteins isolated from abalone shell nacre and growing surfaces of <span class="hlt">calcite</span>. We find that these proteins significantly accelerate the molecular-scale kinetics and, though much larger than atomic steps, alter growth morphology through step-specific interactions that lower their free energies. We propose that these proteins act as surfactants to promote ion attachment at <span class="hlt">calcite</span> surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1087499','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1087499"><span>Upscaling <span class="hlt">Calcite</span> Growth Rates from the Mesoscale to the Macroscale</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bracco, Jacquelyn N.; Stack, Andrew G.; Steefel, Carl I.</p> <p>2013-07-02</p> <p>Quantitative prediction of mineral reaction rates in the subsurface remains a daunting task partly because a key parameter for macroscopic models, the reactive site density, is poorly constrained. Here we report atomic force microscopy (AFM) measurements on the <span class="hlt">calcite</span> surface of monomolecular step densities, treated as equivalent to the reactive site density, as a function of aqueous calcium-to-carbonate ratio and saturation index. Data for the obtuse step orientation are combined with existing step velocity measurements to generate a model that predicts overall macroscopic <span class="hlt">calcite</span> growth rates. The model is quantitatively consistent with several published macroscopic rates under a range of alkaline solution conditions, particularly for two of the most comprehensive data sets without the need for additional fit parameters. The model reproduces peak growth rates and its functional form is simple enough to be incorporated into reactive transport or other macroscopic models designed for predictions in porous media. However, it currently cannot model equilibrium, pH effects, and may overestimate rates at high aqueous calcium-to-carbonate ratios. The discrepancies in rates at high calcium-to-carbonate ratios may be due to differences in pre-treatment, such as exposing the seed material to SI 1.0 to generate/develop growth hillocks, or other factors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.U2001T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.U2001T"><span>Anisotropic Transverse Stress in <span class="hlt">Calcite</span> and Sapphire Measured Using Birefringence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tear, Gareth R.; Chapman, David J.; Eakins, Daniel E.; Proud, William G.</p> <p>2015-06-01</p> <p>Many significant geological minerals have anisotropic crystal structures leading to material properties that are anisotropic, including compressive elastic behaviour. A non-invasive approach to investigate the directional dependence of transverse stress in these materials during shock compression would supplement current understanding. As many geological minerals are transparent and hence optically anisotropic, measuring the change in birefringence induced by transverse stress in the material offers the possibility of a fast, non-invasive approach to probe transverse behaviour. Shock compression experiments have been performed on a-cut <span class="hlt">calcite</span> and a-cut sapphire for strain rates of order 105 s-1 and up to longitudinal stresses of 2 GPa for <span class="hlt">calcite</span> and 12 GPa for sapphire. We present measured changes in birefringence for these materials under shock compression, comparing with current and past literature as well as an in house optical model. The authors would like to thank Mr Steve Johnson and Mr David Pittman for technical support. The Institute of Shock Physics acknowledges the continued support of AWE and Imperial College London.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3730695','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3730695"><span>Crystallographic orientation inhomogeneity and crystal splitting in biogenic <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Checa, Antonio G.; Bonarski, Jan T.; Willinger, Marc G.; Faryna, Marek; Berent, Katarzyna; Kania, Bogusz; González-Segura, Alicia; Pina, Carlos M.; Pospiech, Jan; Morawiec, Adam</p> <p>2013-01-01</p> <p>The <span class="hlt">calcitic</span> prismatic units forming the outer shell of the bivalve Pinctada margaritifera have been analysed using scanning electron microscopy–electron back-scatter diffraction, transmission electron microscopy and atomic force microscopy. In the initial stages of growth, the individual prismatic units are single crystals. Their crystalline orientation is not consistent but rather changes gradually during growth. The gradients in crystallographic orientation occur mainly in a direction parallel to the long axis of the prism, i.e. perpendicular to the shell surface and do not show preferential tilting along any of the <span class="hlt">calcite</span> lattice axes. At a certain growth stage, gradients begin to spread and diverge, implying that the prismatic units split into several crystalline domains. In this way, a branched crystal, in which the ends of the branches are independent crystalline domains, is formed. At the nanometre scale, the material is composed of slightly misoriented domains, which are separated by planes approximately perpendicular to the c-axis. Orientational gradients and splitting processes are described in biocrystals for the first time and are undoubtedly related to the high content of intracrystalline organic molecules, although the way in which these act to induce the observed crystalline patterns is a matter of future research. PMID:23804442</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BGeo...11.2295H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BGeo...11.2295H"><span>Environmental controls on the Emiliania huxleyi <span class="hlt">calcite</span> mass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horigome, M. T.; Ziveri, P.; Grelaud, M.; Baumann, K.-H.; Marino, G.; Mortyn, P. G.</p> <p>2014-04-01</p> <p>Although ocean acidification is expected to impact (bio) calcification by decreasing the seawater carbonate ion concentration, [CO32-], there is evidence of nonuniform response of marine calcifying plankton to low seawater [CO32-]. This raises questions about the role of environmental factors other than acidification and about the complex physiological responses behind calcification. Here we investigate the synergistic effect of multiple environmental parameters, including seawater temperature, nutrient (nitrate and phosphate) availability, and carbonate chemistry on the coccolith <span class="hlt">calcite</span> mass of the cosmopolitan coccolithophore Emiliania huxleyi, the most abundant species in the world ocean. We use a suite of surface (late Holocene) sediment samples from the South Atlantic and southwestern Indian Ocean taken from depths lying above the modern lysocline (with the exception of eight samples that are located at or below the lysocline). The coccolith <span class="hlt">calcite</span> mass in our results presents a latitudinal distribution pattern that mimics the main oceanographic features, thereby pointing to the potential importance of seawater nutrient availability (phosphate and nitrate) and carbonate chemistry (pH and pCO2) in determining coccolith mass by affecting primary calcification and/or the geographic distribution of E. huxleyi morphotypes. Our study highlights the importance of evaluating the combined effect of several environmental stressors on calcifying organisms to project their physiological response(s) in a high-CO2 world and improve interpretation of paleorecords.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15006787','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15006787"><span>Direct observation of microbial inhibition of <span class="hlt">calcite</span> dissolution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lüttge, Andreas; Conrad, Pamela G</p> <p>2004-03-01</p> <p>Vertical scanning interferometry (VSI) provides a method for quantification of surface topography at the angstrom to nanometer level. Time-dependent VSI measurements can be used to study the surface-normal retreat across crystal and other solid surfaces during dissolution or corrosion processes. Therefore, VSI can be used to directly and nondestructively measure mineral dissolution rates with high precision. We have used this method to compare the abiotic dissolution behavior of a representative <span class="hlt">calcite</span> (CaCO(3)) cleavage face with that observed upon addition of an environmental microbe, Shewanella oneidensis MR-1, to the crystal surface. From our direct observations, we have concluded that the presence of the microbes results in a significant inhibition of the rate of <span class="hlt">calcite</span> dissolution. This inhibition appears to be a 2nd-order effect that is related to the formation of etch pits. The opening of etch pits was greatly inhibited in the presence of added bacteria, suggesting that the bacterial cells exert their effect by inhibiting the formation of etch pits at high-energy sites at the crystal surface caused by lattice defects, e.g., screw or point dislocations. The experimental methodology thus provides a nondestructive, directly quantifiable, and easily visualized view of the interactions of microbes and minerals during weathering (or corrosion) processes or during mineral precipitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1172T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1172T"><span>Gas <span class="hlt">Hydrate</span> and Pore Pressure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tinivella, Umberta; Giustiniani, Michela</p> <p>2014-05-01</p> <p>Many efforts have been devoted to quantify excess pore pressures related to gas <span class="hlt">hydrate</span> dissociation in marine sediments below the BSR using several approaches. Dissociation of gas <span class="hlt">hydrates</span> in proximity of the BSR, in response to a change in the physical environment (i.e., temperature and/or pressure regime), can liberate excess gas incrising the local pore fluid pressure in the sediment, so decreasing the effective normal stress. So, gas <span class="hlt">hydrate</span> dissociation may lead to excess pore pressure resulting in sediment deformation or failure, such as submarine landslides, sediment slumping, pockmarks and mud volcanoes, soft-sediment deformation and giant hummocks. Moreover, excess pore pressure may be the result of gas <span class="hlt">hydrate</span> dissociation due to continuous sedimentation, tectonic uplift, sea level fall, heating or inhibitor injection. In order to detect the presence of the overpressure below the BSR, we propose two approachs. The fist approach models the BSR depth versus pore pressure; in fact, if the free gas below the BSR is in overpressure condition, the base of the gas <span class="hlt">hydrate</span> stability is deeper with respect to the hydrostatic case. This effect causes a discrepancy between seismic and theoretical BSR depths. The second approach models the velocities versus gas <span class="hlt">hydrate</span> and free gas concentrations and pore pressure, considering the approximation of the Biot theory in case of low frequency, i.e. seismic frequency. Knowing the P and S seismic velocity from seismic data analysis, it is possibile to jointly estimate the gas <span class="hlt">hydrate</span> and free gas concentrations and the pore pressure regime. Alternatively, if the S-wave velocity is not availbale (due to lack of OBS/OBC data), an AVO analysis can be performed in order to extract information about Poisson ratio. Our modeling suggests that the areas characterized by shallow waters (i.e., areas in which human infrastructures, such as pipelines, are present) are significantly affected by the presence of overpressure condition</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22298911','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22298911"><span><span class="hlt">Hydration</span> of highly charged ions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hofer, Thomas S; Weiss, Alexander K H; Randolf, Bernhard R; Rode, Bernd M</p> <p>2011-08-01</p> <p>Based on a series of ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations, the broad spectrum of structural and dynamical properties of <span class="hlt">hydrates</span> of trivalent and tetravalent ions is presented, ranging from extreme inertness to immediate hydrolysis. Main group and transition metal ions representative for different parts of the periodic system are treated, as are 2 threefold negatively charged anions. The results show that simple predictions of the properties of the <span class="hlt">hydrates</span> appear impossible and that an accurate quantum mechanical simulation in cooperation with sophisticated experimental investigations seems the only way to obtain conclusive results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011987','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011987"><span>Crystal growth of <span class="hlt">calcite</span> from calcium bicarbonate solutions at constant PCO2 and 25°C: a test of a <span class="hlt">calcite</span> dissolution model</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reddy, Michael M.; Plummer, L. Neil; Busenberg, E.</p> <p>1981-01-01</p> <p>A highly reproducible seeded growth technique was used to study <span class="hlt">calcite</span> crystallization from calcium bicarbonate solutions at 25°C and fixed carbon dioxide partial pressures between 0.03 and 0.3 atm. The results are not consistent with empirical crystallization models that have successfully described <span class="hlt">calcite</span> growth at low PCO2 (< 10−3 atm). Good agreement was found between observed crystallization rates and those calculated from the <span class="hlt">calcite</span> dissolution rate law and mechanism proposed by Plummer et al. (1978).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1447..569C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1447..569C"><span>Improvement in hardness of soda-<span class="hlt">lime</span>-silica glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chakraborty, Riya; De, Moumita; Roy, Sudakshina; Dey, Arjun; Biswas, Sampad K.; Middya, Tapas Ranjan; Mukhopadhyay, Anoop K.</p> <p>2012-06-01</p> <p>Hardness is a key design parameter for structural application of brittle solids like glass. Here we report for the first time the significant improvement of about 10% in Vicker's hardness of a soda-<span class="hlt">lime</span>-silica glass with loading rate in the range of 0.1-10 N.s-1. Corroborative dark field optical and scanning electron microscopy provided clue to this improvement through evidence of variations in spatial density of shear deformation band formation as a function of loading rate.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19700000035','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19700000035"><span>Compact apparatus for photogeneration of <span class="hlt">hydrated</span> electrons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hart, E.; Schmidt, K.</p> <p>1970-01-01</p> <p>Flash-photolysis instrument generates <span class="hlt">hydrated</span> electrons and studies their reactions. It has a three-dimensional, multiple-reaction cell and the capacity to produce up to .1 micromole <span class="hlt">hydrated</span> electron in a single 40 microsec light pulse.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.eia.gov/naturalgas/archive/update.pdf','EIAPUBS'); return false;" href="http://www.eia.gov/naturalgas/archive/update.pdf"><span>Natural Gas <span class="hlt">Hydrates</span> Update 1998-2000</span></a></p> <p><a target="_blank" href="http://www.eia.doe.gov/reports/">EIA Publications</a></p> <p></p> <p>2001-01-01</p> <p>Significant events have transpired on the natural gas <span class="hlt">hydrate</span> research and development front since "Future Supply Potential of Natural Gas <span class="hlt">Hydrates</span>" appeared in Natural Gas 1998 Issues and Trends and in the Potential Gas Committee's 1998 biennial report.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22395928','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22395928"><span>Methods to determine <span class="hlt">hydration</span> states of minerals and cement <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Baquerizo, Luis G.; Matschei, Thomas; Scrivener, Karen L.; Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars</p> <p>2014-11-15</p> <p>This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement <span class="hlt">hydrates</span> in different <span class="hlt">hydration</span> states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of <span class="hlt">hydrated</span> phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in <span class="hlt">hydrated</span> cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na{sub 2}SO{sub 4}–H{sub 2}O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6240753','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6240753"><span>Energy reduction in beet sugar processing by cossette <span class="hlt">liming</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Randall, J.M.; Camirand, W.M.; Neumann, H.J.</p> <p>1981-01-01</p> <p>Under appropriate conditions of temperature and fresh Ca(OH)/sub 2/ application, demethylation occurs in the pectin in the cell walls of sugar beet cossettes, allowing Ca/sup 2 +/ to precipitate the pectin as calcium pectate. The calcium pectate will not degrade and pass into solution during subsequent hot extraction of sugar from the cossettes. This retention of pectin in the pulp was shown by 10 to 20% increases in solids weight in the pulp for a number of processing conditions. The toughened pulp produced by retention of calcium pectate allowed easier mechanical dewatering of the pulp which could save considerably on the heat normally required to dry the pulp for cattle feed. Beyond data reported in this paper, there are qualitative indications that the sugar juice extracted from <span class="hlt">limed</span> cossettes is purer than standard juice, for pectin and colloidal materials remain in the pulp. Thus, much less purification of the juice with <span class="hlt">lime</span> would be necessary than is required in standard beet-sugar processing, and the current 2% CaO used for purification may be cut almost in half. This represents another energy saving, for production of CaO at the factory is a major consumer of energy. These, along with other possible energy savings resulting from cossette <span class="hlt">liming</span> (such as less water used for extraction, cold extraction, ion exchange of the purer juice), could produce an overall saving up to 20% of the energy currently used in beet-sugar processing. Some of these possibilities will be further investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25494537','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25494537"><span>Flavor chemistry of lemon-<span class="hlt">lime</span> carbonated beverages.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hausch, Bethany J; Lorjaroenphon, Yaowapa; Cadwallader, Keith R</p> <p>2015-01-14</p> <p>The most potent aroma-active components of Sprite (SP), Sierra Mist (SM), and 7UP (7UP) were identified. Aroma extracts were prepared by liquid–liquid continuous extraction/solvent-assisted flavor evaporation (LLCE/SAFE). Twenty-eight compounds were detected by gas chromatography–olfactometry (GC-O) with linalool (floral, lavender), octanal (pungent orange), and 2,3-dehydro-1,8-cineole (minty) determined to be predominant aroma compounds based on their high flavor dilution (FD) factors by aroma extract dilution analysis (AEDA). The data indicate that lemon-<span class="hlt">lime</span> flavor is composed of a small number of compounds (22 at the most in SM), and only a subset of these may be important because many compounds were detected only at low FD factors. Predominant aroma compounds (23) were quantified using static headspace solid phase microextraction (SPME) combined with stable isotope dilution assays (SIDA). In contrast to FD factors, the calculated odor-activity values (OAVs) indicate that octanal and limonene make the greatest contribution to the overall aroma of lemon-<span class="hlt">lime</span> carbonated beverages, followed by nonanal, decanal, linalool, 1,8-cineole, and geranyl acetate. The results demonstrate that lemon-<span class="hlt">lime</span> carbonated beverages share many of the same compounds but the relative abundance of these compounds varies by brand.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6822640','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6822640"><span><span class="hlt">Lime</span> FGD system and sludge disposal case study. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, E.O.; Morgan, W.E.; Noland, J.W.; Quinlan, R.T.; Stresewski, J.E.; Swenson, D.O.</p> <p>1980-11-01</p> <p>Selecting and installing a flue gas desulfurization (FGD) system and a sludge disposal system at a utility electric generation plant is no easy task. Approximately 21,000 MW of FGD and sludge disposal systems are presently operating with another 28,000 MW of FGD and sludge disposal systems under construction or planned. With the new EPA regulations requiring an FGD system on essentially every new coal-fired utility electric generation unit, the ability to decide on the most advantageous FGD and sludge disposal systems which are technically, economically, and environmentally acceptable can result in savings of $7.40/kW to the utility. This case study describes the step-by-step design decisions and equipment selections for a hypothetical <span class="hlt">lime</span> FGD and sludge disposal system for a new 500 MW coal-fired electric generation unit. The hypothetical FGD and sludge disposal systems are based on actual installations. This case study demonstrates the methods by which utility personnel can effectively utilize the information contained in the <span class="hlt">Lime</span> FGD Systems Data Book (FP-1030) and the FGD Sludge Disposal Manual (FP-977) to select the most advantageous <span class="hlt">lime</span> FGD and sludge disposal systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=309205&keyword=land%20and%20waste%20management&subject=land%20and%20waste%20management%20research&showcriteria=2&fed_org_id=111&datebeginpublishedpresented=03/28/2012&dateendpublishedpresented=03/28/2017&sortby=pubdateyear','PESTICIDES'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=309205&keyword=land%20and%20waste%20management&subject=land%20and%20waste%20management%20research&showcriteria=2&fed_org_id=111&datebeginpublishedpresented=03/28/2012&dateendpublishedpresented=03/28/2017&sortby=pubdateyear"><span>Evaluation of the impact of <span class="hlt">lime</span> softening waste disposal in ...</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>Drinking water treatment residues (WTR), generated from the <span class="hlt">lime</span> softening processes, are commonly reused or disposed of in a number of applications; these include use as a soil amendment or a subsurface fill. Recently questions were posed by the Florida regulatory community on whether <span class="hlt">lime</span> WTR that contained a small percentage of other treatment additives could appropriately be characterized as <span class="hlt">lime</span> WTR, in terms of its total element content and leachability. A study was done using a broad range of leaching tests, including a framework of tests recently adopted by the United States-Environmental Protection Agency (EPA) and tests that were modified to account for scenario specific conditions, such as the presence of natural organic matter (NOM). The results of these additional leaching tests demonstrated that certain applications, including disposal in a water body with NOM or in placement anaerobic environment, did result in increased leaching of elements such as Fe, and that a site specific assessment should be conducted prior to using WTR in these types of applications. This study illustrates the importance of leaching test selection when attempting to provide an estimation of release in practice. Although leaching tests are just one component in a beneficial use assessment and other factors including aquifer and soil properties play a significant role in the outcome, leaching tests should be tailored to most appropriately represent the scenario or reuse ap</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19540566','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19540566"><span>Speciation of aluminium, arsenic and molybdenum in excessively <span class="hlt">limed</span> lakes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sjöstedt, Carin; Wällstedt, Teresia; Gustafsson, Jon Petter; Borg, Hans</p> <p>2009-09-01</p> <p>The possible existence of the potentially toxic oxyanions of Al (Al(OH)(4)(-)), As (HAsO(4)(2-)), and Mo (MoO(4)(2-)) was examined in excessively <span class="hlt">limed</span> lakes. In-situ dialysis (MWCO 1 kDa) was performed in the surface and bottom waters of two excessively <span class="hlt">limed</span> lakes (pH 7.1-7.7) and one acidic lake (pH approximately 5.4). The dialysable metal concentrations were compared to the equilibrium distribution of species as calculated with the geochemical code Visual MINTEQ incorporating the CD-MUSIC and Stockholm Humic models for complexation onto colloidal ferrihydrite and dissolved organic matter. Arsenic and molybdenum in the excessively <span class="hlt">limed</span> lakes were to a large extent present in the dialysable fraction (>79% and >92% respectively). They were calculated to exist as free or adsorbed oxyanions. Most of the Al was observed to reside in the colloidal fraction (51-82%). In agreement with this, model predictions indicated aluminium to be present mostly as colloids or bound to dissolved organic matter. Only a small fraction was modelled as Al(OH)(4)(-) ions. In most cases, modelled values were in agreement with the dialysis results. The free concentrations of the three oxyanions were mostly low compared to toxic levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA616845','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA616845"><span>Molecular Dynamics Modeling of <span class="hlt">Hydrated</span> Calcium-Silicate-<span class="hlt">Hydrate</span> (CSH) Cement Molecular Structure</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2014-08-30</p> <p>properties of key <span class="hlt">hydrated</span> cement constituent calcium-silicate-<span class="hlt">hydrate</span> (CSH) at the molecular, nanometer scale level. Due to complexity, still unknown...public release; distribution is unlimited. Molecular Dynamics Modeling of <span class="hlt">Hydrated</span> Calcium-Silicate- <span class="hlt">Hydrate</span> (CSH) Cement Molecular Structure The views... Cement Molecular Structure Report Title Multi-scale modeling of complex material systems requires starting from fundamental building blocks to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/factsheet/fs021-01/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/factsheet/fs021-01/"><span>Natural gas <span class="hlt">hydrates</span>; vast resource, uncertain future</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, T.S.</p> <p>2001-01-01</p> <p>Gas <span class="hlt">hydrates</span> are naturally occurring icelike solids in which water molecules trap gas molecules in a cagelike structure known as a clathrate. Although many gases form <span class="hlt">hydrates</span> in nature, methane <span class="hlt">hydrate</span> is by far the most common; methane is the most abundant natural gas. The volume of carbon contained in methane <span class="hlt">hydrates</span> worldwide is estimated to be twice the amount contained in all fossil fuels on Earth, including coal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1340531','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1340531"><span><span class="hlt">Hydration</span> and Thermal Expansion in Anatase Nanoparticles</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhu, He; Li, Qiang; Ren, Yang; Fan, Longlong; Chen, Jun; Deng, Jinxia; Xing, Xianran</p> <p>2016-06-06</p> <p>A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface <span class="hlt">hydration</span>. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a <span class="hlt">hydrated</span> surface and is positive without a <span class="hlt">hydrated</span> surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific <span class="hlt">hydrated</span> surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27270568','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27270568"><span><span class="hlt">Hydration</span> and Thermal Expansion in Anatase Nanoparticles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, He; Li, Qiang; Ren, Yang; Fan, Longlong; Chen, Jun; Deng, Jinxia; Xing, Xianran</p> <p>2016-08-01</p> <p>A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface <span class="hlt">hydration</span>. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a <span class="hlt">hydrated</span> surface and is positive without a <span class="hlt">hydrated</span> surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific <span class="hlt">hydrated</span> surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21036890','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21036890"><span>Characteristics and reactivity of rapidly <span class="hlt">hydrated</span> sorbent for semidry flue gas desulfurization</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jie Zhang; Changfu You; Suwei Zhao; Changhe Chen; Haiying Qi</p> <p>2008-03-01</p> <p>The semidry flue gas desulfurization (FGD) process has many advantages over the wet FGD process for moving sulfur dioxide emissions from pulverized coal-fired power plants. Semidry FGD with a rapidly <span class="hlt">hydrated</span> sorbent was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. The sorbent was made from lumps of <span class="hlt">lime</span> and coal fly ash. The desulfurization efficiency was measured for various operating parameters, including the sorbent recirculation rate and the water spray method. The experimental results show that the desulfurization efficiencies of the rapidly <span class="hlt">hydrated</span> sorbent were 1.5-3.0 times higher than a commonly used industrial sorbent for calcium to sulfur molar ratios from 1.2 to 3.0, mainly due to the higher specific surface area and pore volume. The Ca(OH){sub 2} content in the cyclone separator ash was about 2.9% for the rapidly <span class="hlt">hydrated</span> sorbent and was about 0.1% for the commonly used industrial sorbent, due to the different adhesion between the fine Ca(OH){sub 2} particles and the fly ash particles, and the low cyclone separation efficiency for the fine Ca(OH){sub 2} particles that fell off the sorbent particles. Therefore the actual recirculation rates of the active sorbent with Ca(OH){sub 2} particles were higher for the rapidly <span class="hlt">hydrated</span> sorbent, which also contributed to the higher desulfurization efficiency. The high fly ash content in the rapidly <span class="hlt">hydrated</span> sorbent resulted in good operating stability. The desulfurization efficiency with upstream water spray was 10-15% higher than that with downstream water spray. 20 refs., 7 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17267106','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17267106"><span>Remediation of Pb-contaminated soils by washing with hydrochloric acid and subsequent immobilization with <span class="hlt">calcite</span> and allophanic soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Isoyama, Masahiro; Wada, Shin-Ichiro</p> <p>2007-05-17</p> <p>Removal of heavy metals from contaminated soil is not popular because of its high cost. Reducing the bioaccessible heavy metals content to an allowable level by washing with inorganic acids and subsequent immobilization of remained metals may be a low cost option for soil remediation. The applicability of this combined treatment was investigated using three different types of soil, a kaolinitic, a smectitic and an allophanic soil, which were artificially contaminated with Pb. The effectiveness of the treatment was evaluated using two main criteria: (i) reduction of the HCl extractable Pb (bioaccessible Pb) below 150 mg kg(-1), reduction of water extractable Pb below the concentration of 0.01 mg L(-1). These values correspond to allowable levels suggested by the Japanese Ministry of Environment. The soils were washed batch-wise at a solution to soil ratio of 5 L kg(-1) successively with 1 mol L(-1) HCl and 0.1 mol L(-1) CaCl(2) solutions. The two solutions were separated by filtration from one batch and reused for washing the next batch of soil without processing. The Pb concentration in the solutions increased after repeated use and removal efficiency gradually declined. The efficiency of the treatment was highly dependent on the type of soil. In the kaolinitic soil, HCl extractable Pb content of the soil from the first batch was about 50 mg kg(-1) and it exceeded 150 mg kg(-1) in that from sixth batch. But the combined soils from 1st to 10th batches gave bioaccessible Pb content barely below 150 mg kg(-1). For the smectitic soil having higher cation exchange capacity, the acceptable number of times of reuse was estimated to be 4. For the allophanic soil, treatment with the HCl solution was efficient only for the first batch of the soil, and the reuse of the acid solution was found to be ineffective. The application of 50 g kg(-1) of <span class="hlt">calcite</span> or slacked <span class="hlt">lime</span> was effective for reducing the water extractable Pb content. To keep soil pH near neutral and secure long</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-07-06/pdf/2012-16550.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-07-06/pdf/2012-16550.pdf"><span>77 FR 40032 - Methane <span class="hlt">Hydrate</span> Advisory Committee</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-07-06</p> <p>... Methane <span class="hlt">Hydrate</span> Advisory Committee AGENCY: Office of Fossil Energy, Department of Energy. ACTION: Notice of open meeting. SUMMARY: This notice announces a meeting of the Methane <span class="hlt">Hydrate</span> Advisory Committee.... SUPPLEMENTARY INFORMATION: Purpose of the Committee: The purpose of the Methane <span class="hlt">Hydrate</span> Advisory Committee is...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-03-04/pdf/2010-4519.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-03-04/pdf/2010-4519.pdf"><span>75 FR 9886 - Methane <span class="hlt">Hydrate</span> Advisory Committee</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-03-04</p> <p>... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Methane... meeting. SUMMARY: This notice announces a meeting of the Methane <span class="hlt">Hydrate</span> Advisory Committee. Federal... Methane <span class="hlt">Hydrate</span> Advisory Committee is to provide advice on potential applications of methane <span class="hlt">hydrate</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=237750','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=237750"><span>Predicting <span class="hlt">Calcite</span> (CaCO3) Requirements of Sphagnum Peat Moss from pH Titration Curves</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p><span class="hlt">Liming</span> materials are required to neutralize acidity in peat moss to make it a suitable substrate for growing container crops. A series of time-consuming incubations of peat:<span class="hlt">lime</span> mixtures are typically used to determine the <span class="hlt">liming</span> rate to achieve a desired pH. Our objective was to evaluate the util...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.3783R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3783R"><span>Interactions of arsenic with <span class="hlt">calcite</span> surfaces revealed by in-situ nanoscale imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Renard, Francois; Putnis, Christine; Montes-Hernandez, German; Ruiz-Agudo, Encarnacion; Hövelmann, Jörn; Sarret, Géraldine</p> <p>2015-04-01</p> <p>Arsenic dissolved in water represents a key environmental and health challenge because several million people are under the threat of contamination. In calcareous environments <span class="hlt">calcite</span> may play an important role in arsenic solubility and transfer in water. Arsenic-<span class="hlt">calcite</span> interactions remain controversial, especially for As(III) which was proposed to be either incorporated as such, or as As(V) after oxidation. Here, we provide the first time-lapse in-situ study of <span class="hlt">calcite</span> dissolution and growth in the presence of solutions with various amounts of As(III) or As(V). This was performed at room temperature and pH range 6-9 using a flow through cell connected to an atomic force microscope (AFM), to study the evolution of the (10-14) <span class="hlt">calcite</span> cleavage surface morphology. Reaction products were then characterized by Raman spectroscopy. In parallel, co-precipitation experiments with either As(III) or As(V) were performed in batch reactors, and the speciation of arsenic in the resulting solids was studied by X-ray absorption spectroscopy (XAS). For As(V), AFM results showed that it interacts strongly with the <span class="hlt">calcite</span> surface, and XAS results showed that As(V) was mostly incorporated in the <span class="hlt">calcite</span> structure. For As(III), AFM results showed much less impact on <span class="hlt">calcite</span> growth and dissolution and less incorporation was observed. This was confirmed by XAS results that indicate that As(III) was partly oxidized into As(V) before being incorporated into <span class="hlt">calcite</span> and the resulting <span class="hlt">calcite</span> contained 36% As(III) and 64% As(V). All these experimental results confirm that As(V) has a much stronger interaction with <span class="hlt">calcite</span> than As(III) and that <span class="hlt">calcite</span> may represent an important reservoir for arsenic in various geological environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996GeCoA..60.4417V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996GeCoA..60.4417V"><span>Paleotransport of lanthanides and strontium recorded in <span class="hlt">calcite</span> compositions from tuffs at Yucca Mountain, Nevada, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vaniman, David T.; Chipera, Steve J.</p> <p>1996-11-01</p> <p>Secondary <span class="hlt">calcite</span> occurs in both saturated and unsaturated hydrologic zones (SZ and UZ, respectively) in the tuffs at Yucca Mountain, Nevada, USA. In the upper UZ, the major constituents of the <span class="hlt">calcite</span> crystal structure (C, O) have surface origins. At greater depth there is a “barren zone,” straddling the water table, where <span class="hlt">calcite</span> is rare and mixing of surface and subsurface sources may occur. Deep in the SZ, distinctive Mn <span class="hlt">calcites</span> reflect deep sources, including Ca released as analcime or albite formed and carbonates derived from underlying Paleozoic rocks. In the UZ and in the barren zone, above the deep Mn <span class="hlt">calcites</span>, variations in <span class="hlt">calcite</span> lanthanide chemistry can be used to distinguish rhyolitic from quartz-latitic sources. Lanthanide ratios and Sr contents of <span class="hlt">calcites</span> record the chemical evolution of waters flowing through the UZ and upper SZ. Variations in <span class="hlt">calcite</span> chemistry in the UZ and in the barren zone show that (1) Sr, which is readily exchanged with clays or zeolites, is essentially removed from some flowpaths that are in contact with these minerals and (2) traces of Mn oxides found in the tuffs have a significant effect on groundwater chemistry in the UZ and in the barren zone by removing almost all Ce from solution (evidenced by characteristic Ce depletions in <span class="hlt">calcite</span> throughout this zone). Extreme Ce removal may be a result of Ce oxidation (Ce 3+→ Ce 4+) at the surfaces of some Mn oxides, particularly rancieite. Higher Sr contents and lack of Ce depletions in the deeper Mn <span class="hlt">calcites</span> reflect different ages, origins, and transport systems. The <span class="hlt">calcite</span> record of lanthanide and Sr transport in the UZ shows that minor minerals (clays and zeolites) and even trace minerals (Mn oxides) will affect the compositions of groundwaters that flow over distances greater than a few tens of meters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24059213','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24059213"><span>[Study on the traditional <span class="hlt">lime</span> mortar from the memorial archway in the southern Anhui province].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wei, Guo-Feng; Sun, Sheng; Wang, Cheng-Xing; Zhang, Bing-Jian; Chen, Xi-Min</p> <p>2013-07-01</p> <p>The traditional <span class="hlt">lime</span> mortar was investigated by means of scanning electron microscope (SEM), X-ray diffractometry and Fourier transform infrared spectrometry (FTIR). The results show that the mortar from the memorial archway in the southern Anhui province was the organic-inorganic composite materials composed of <span class="hlt">lime</span> with tung oil or sticky rice. It was found that the excellent performance of the tung oil-<span class="hlt">lime</span> mortar can be explained by the compact lamellar organic-inorganic composite structure that was produced by carbonization reaction of <span class="hlt">lime</span>, cross-linking reactions of tung oil and oxygen and complexing reaction of Ca2+ and -COO-. The compact micro-structure of sticky rice-<span class="hlt">lime</span> mortar, which was produced due to carbonation process of <span class="hlt">lime</span> controlled by amylopectin, should be the cause of the good performance of this kind of organic-inorganic mortar.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.146h4501A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.146h4501A"><span>Is Br2 <span class="hlt">hydration</span> hydrophobic?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alcaraz-Torres, A.; Gamboa-Suárez, A.; Bernal-Uruchurtu, M. I.</p> <p>2017-02-01</p> <p>The spectroscopic properties of bromine in aqueous systems suggest it can behave as either hydrophilic or hydrophobic solute. In small water clusters, the halogen bond and the hydrogen-halogen interaction are responsible for its specific way of binding. In water <span class="hlt">hydrates</span>, it is efficiently hosted by two different cages forming the crystal structure and it has been frequently assumed that there is little or no interaction between the guest and the host. Bromine in liquid solution poses a challenging question due to its non-negligible solubility and the large blue shift measured in its absorption spectra. Using a refined semi-empirical force field, PM3-PIF, we performed a Born-Oppenheimer molecular dynamics study of bromine in liquid water. Here we present a detailed study in which we retrieved the most representative <span class="hlt">hydration</span> structures in terms of the most frequent positions around bromine and the most common water orientations. Albeit being an approximate description of the total <span class="hlt">hydration</span> phenomenon, it captures the contribution of the leading molecular interactions in form of the recurrent structures. Our findings confirm that the spectroscopic signature is mainly caused by the closest neighbors. The dynamics of the whole first <span class="hlt">hydration</span> shell strongly suggests that the external molecules in that structure effectively isolate the bulk from the presence of bromine. The solvation structure fluctuates from a hydrophilic to a hydrophobic-like environment along the studied trajectory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014CPL...610..375K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014CPL...610..375K"><span>Attraction between <span class="hlt">hydrated</span> hydrophilic surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kanduč, Matej; Schneck, Emanuel; Netz, Roland R.</p> <p>2014-08-01</p> <p>According to common knowledge, hydrophilic surfaces repel via <span class="hlt">hydration</span> forces while hydrophobic surfaces attract, but mounting experimental evidence suggests that also hydrophilic surfaces can attract. Using all-atom molecular dynamics simulations at prescribed water chemical potential we study the crossover from <span class="hlt">hydration</span> repulsion to hydrophobic attraction for planar polar surfaces of varying stiffness and hydrogen-bonding capability. Rescaling the partial charges of the polar surface groups, we cover the complete spectrum from very hydrophobic surfaces (characterized by contact angles θ ≃ 135°) to hydrophilic surfaces exhibiting complete wetting (θ = 0°). Indeed, for a finite range θadh < θ < 90°, we find a regime where hydrophilic surfaces attract at sub-nanometer separation and stably adhere without intervening water. The adhesive contact angle θadh depends on surface type and lies in the range 65° < θadh < 80°, in good agreement with experiments. Analysis of the total number of hydrogen bonds (HBs) formed by water and surface groups rationalizes this crossover between <span class="hlt">hydration</span> repulsion and hydrophilic attraction in terms of a subtle balance: Highly polar surfaces repel because of strongly bound <span class="hlt">hydration</span> water, less polar hydrophilic surfaces attract because water-water HBs are preferred over surface-water HBs. Such solvent reorganization forces presumably underlie also other important phenomena, such as selective ion adsorption to interfaces as well as ion pair formation. </ce:biography><ce:biography </ce:biography><ce:biography </ce:biography></ja:tail></ja:article></doc:document></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17768978','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17768978"><span><span class="hlt">Hydration</span> rind dates rhyolite flows.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Friedman, I</p> <p>1968-02-23</p> <p><span class="hlt">Hydration</span> of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70011545','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70011545"><span><span class="hlt">Hydration</span> rind dates rhyolite flows</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Friedman, I.</p> <p>1968-01-01</p> <p><span class="hlt">Hydration</span> of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21095725','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21095725"><span>Terahertz sensing of corneal <span class="hlt">hydration</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Singh, Rahul S; Tewari, Priyamvada; Bourges, Jean Louis; Hubschman, Jean Pierre; Bennett, David B; Taylor, Zachary D; Lee, H; Brown, Elliott R; Grundfest, Warren S; Culjat, Martin O</p> <p>2010-01-01</p> <p>An indicator of ocular health is the hydrodyanmics of the cornea. Many corneal disorders deteriorate sight as they upset the normal hydrodynamics of the cornea. The mechanisms include the loss of endothelial pump function of corneal dystophies, swelling and immune response of corneal graft rejection, and inflammation and edema, which accompany trauma, burn, and irritation events. Due to high sensitivity to changes of water content in materials, a reflective terahertz (300 GHz and 3 THz) imaging system could be an ideal tool to measure the <span class="hlt">hydration</span> level of the cornea. This paper presents the application of THz technology to visualize the <span class="hlt">hydration</span> content across ex vivo porcine corneas. The corneas, with a thickness variation from 470 - 940 µm, were successfully imaged using a reflective pulsed THz imaging system, with a maximum SNR of 50 dB. To our knowledge, no prior studies have reported on the use of THz in measuring <span class="hlt">hydration</span> in corneal tissues or other ocular tissues. These preliminary findings indicate that THz can be used to accurately sense <span class="hlt">hydration</span> levels in the cornea using a pulsed, reflective THz imaging system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1213531','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1213531"><span>Kinetics and Mechanisms of <span class="hlt">Calcite</span> Reactions with Saline Waters</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorman, Brian P</p> <p>2015-09-02</p> <p>Project Description: The general objective of the proposed research is to determine the kinetics and mechanisms of <span class="hlt">calcite</span> reactions with saline waters over a wide range of saline water composition, pCO<sub>2</sub>, and modest ranges in T and P. This will be accomplished by studying both reaction rates and solubility from changes in solution chemistry, and making nanoscale observations of <span class="hlt">calcite</span> precipitate surface morphology and composition at the micro-to-nano-scale to provide an understanding of controlling reaction mechanisms and pathways. The specific objectives necessary to reach the general objective are: a) determination of how pCO<sub>2</sub>, Ca<sup>2+</sup>, ionic strength and “foreign” ions influence reaction rates; and b) investigate the influence of these parameters on apparent kinetic solubility from dissolution and precipitation reactions. This information will clearly be central to the construction of reliable reaction-transport models to predict reservoir and formation response to increased CO<sub>2</sub> in saline waters. This program was initially collaborative with John Morse at Texas A&M, however his passing shortly after the beginning of this program resulted in abbreviated research time and effort. Summary of Results: Early studies using electron microscopy and spectroscopy indicated that carbonate precipitation from natural seawater (NSW) conditions onto aragonite substrates was mediated by a surface amorphous calcium carbonate layer. It was hypothesized that this ACC layer (observed after < 5days reaction time) was responsible for the abnormal reaction kinetics and also served as a metastable seed layer for growth of epitaxial aragonite. Further studies of the ACC formation mechanism indicated a strong dependence on the Mg concentration in solution. Subsequent studies at shorter times (10 hrs) on <span class="hlt">calcite</span> substrates and in a wide range of supersaturation conditions did not indicate any ACC layer. Instead, an epitaxial layer by layer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.3649S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.3649S"><span>Planktic Foraminiferal Contribution To The Marine <span class="hlt">Calcite</span> Budget</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schiebel, R.</p> <p></p> <p>The vertical flux and sedimentation of planktic foraminiferal tests is quantified and a global planktic foraminiferal CaCO3 budget is presented. The eastern North Atlantic, the Arabian Sea, and the Caribbean were identified as key areas for this investiga- tion, covering a wide spectrum of ecological conditions and faunal compositions. Test and <span class="hlt">calcite</span> flux rates are calculated according to the distribution of species obtained from multinet and sediment trap samples. Population dynamics of modern plank- tic foraminifers are discussed as a prerequesite for the quantification of the <span class="hlt">calcite</span> budget, highlighting the importance of ecological, autecological (e.g., reproduction), and biogeochemical conditions that determine the presence or absence of species. To complete the open-marine, particulate CaCO3 inventory, the contribution of coccol- ithophores, pteropods, and calcareous dinophytes is discussed. It is assumed that the global planktic foraminiferal <span class="hlt">calcite</span> flux at 100 m depth amounts to 1.3-3.2 Gigatons per year, equivalent to 23-56% of the total open marine CaCO3 flux. The preservation of tests varies on a regional and temporal scale, and is affected by local hydrogra- phy and dissolution susceptibility of planktic foraminiferal tests. Throughout most of the year (off-peak periods) a major portion of tests is dissolved above 700 m water depth while individually settling through the water column, with on average only 1- 3% of the initially exported CaCO3 reaching the deep sea floor. Pulsed flux events, mass dumps of fast settling particles, yield a major contribution of the tests to the formation of deep-sea sediments. On an annual average, about one fourth of the ini- tially produced planktic foraminiferal test CaCO3 may settle on the sea floor. The total planktic foraminiferal contribution of CaCO3 to global deep-marine surface sediments amounts to 0.36-0.88 Gt per year, which is 32-80% of the total CaCO3 budget that is estimated at 1.1 Gt per year (e</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/fs/2007/3041/pdf/FS-2007-3041.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/fs/2007/3041/pdf/FS-2007-3041.pdf"><span>Thermal properties of methane gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Waite, William F.</p> <p>2007-01-01</p> <p>Gas <span class="hlt">hydrates</span> are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas <span class="hlt">hydrates</span> are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring <span class="hlt">hydrate</span> guest species. Methane <span class="hlt">hydrates</span>, also called simply “gas <span class="hlt">hydrates</span>,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane <span class="hlt">hydrate</span> breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas <span class="hlt">hydrates</span> is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas <span class="hlt">hydrates</span> also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas <span class="hlt">hydrate</span> stability is sensitive to temperature changes. To understand methane release from gas <span class="hlt">hydrate</span>, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane <span class="hlt">hydrate</span> thermal properties at conditions relevant to accumulations of naturally occurring methane <span class="hlt">hydrate</span>. Prior to this work, thermal properties for gas <span class="hlt">hydrates</span> generally were measured on analog systems such as ice and non-methane <span class="hlt">hydrates</span> or at temperatures below freezing; these conditions limit direct comparisons to methane <span class="hlt">hydrates</span> in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, λ: if λ is high, heat travels easily through the material. - Thermal diffusivity, κ: if κ is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6717417','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6717417"><span>Short-term responses of wetland vegetation after <span class="hlt">liming</span> of an Adirondack watershed</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mackun, I.R.; Leopold, D.J.; Raynal, D.J. )</p> <p>1994-08-01</p> <p>Watershed <span class="hlt">liming</span> has been suggested as a long-term mitigation strategy for lake acidity, particularly in areas subject to high levels of acidic deposition. However, virtually no information has been available on the impacts of <span class="hlt">liming</span> on wetland vegetation. In 1989, 1100 Mg of limestone (83.5% CaCO[sub 3]) were aerially applied to 48% (100 ha) of the Woods Lake watershed in the west-central Adirondack region of New York as part of the first comprehensive watershed <span class="hlt">liming</span> study in North America. We inventoried wetland vegetation in 1.0-m[sup 2] plots before <span class="hlt">liming</span> and during the subsequent 2 yr. Within this period <span class="hlt">liming</span> influenced the cover, frequency, or importance values of only 6 of 64 wetland taxa. The cover of Sphagnum spp. and of the cespitose sedge Carex interior decreased in control relative to <span class="hlt">limed</span> plots, and cover of the rhizomatous sedge Cladium mariscoides increased nearly threefold in <span class="hlt">limed</span> areas. These two sedges, which are relatively tall, are characteristic of more calcareous habitats. Cover of the grass Muhlenbergia uniflora, cover and importance were adversely affected or inhibited by <span class="hlt">lime</span>. It is unclear whether <span class="hlt">liming</span> directly inhibited the growth of these three small-statured species, or whether the adverse effects of <span class="hlt">lime</span> were mediated through shifts in competitive interactions with other species. The limited responses that we observed to <span class="hlt">liming</span>, along with changes that occurred in control plots over the study period, may indicate that in the short term watershed <span class="hlt">liming</span> was no more of a perturbation than the environmental factors responsible for natural annual variation in wetland communities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4776460','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4776460"><span>Mesoscale texture of cement <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ioannidou, Katerina; Krakowiak, Konrad J.; Bauchy, Mathieu; Hoover, Christian G.; Masoero, Enrico; Yip, Sidney; Ulm, Franz-Josef; Levitz, Pierre; Pellenq, Roland J.-M.; Del Gado, Emanuela</p> <p>2016-01-01</p> <p>Strength and other mechanical properties of cement and concrete rely upon the formation of calcium–silicate–<span class="hlt">hydrates</span> (C–S–H) during cement <span class="hlt">hydration</span>. Controlling structure and properties of the C–S–H phase is a challenge, due to the complexity of this <span class="hlt">hydration</span> product and of the mechanisms that drive its precipitation from the ionic solution upon dissolution of cement grains in water. Departing from traditional models mostly focused on length scales above the micrometer, recent research addressed the molecular structure of C–S–H. However, small-angle neutron scattering, electron-microscopy imaging, and nanoindentation experiments suggest that its mesoscale organization, extending over hundreds of nanometers, may be more important. Here we unveil the C–S–H mesoscale texture, a crucial step to connect the fundamental scales to the macroscale of engineering properties. We use simulations that combine information of the nanoscale building units of C–S–H and their effective interactions, obtained from atomistic simulations and experiments, into a statistical physics framework for aggregating nanoparticles. We compute small-angle scattering intensities, pore size distributions, specific surface area, local densities, indentation modulus, and hardness of the material, providing quantitative understanding of different experimental investigations. Our results provide insight into how the heterogeneities developed during the early stages of <span class="hlt">hydration</span> persist in the structure of C–S–H and impact the mechanical performance of the hardened cement paste. Unraveling such links in cement <span class="hlt">hydrates</span> can be groundbreaking and controlling them can be the key to smarter mix designs of cementitious materials. PMID:26858450</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24972459','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24972459"><span>Physical activity, <span class="hlt">hydration</span> and health.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marcos, Ascensión; Manonelles, Pedro; Palacios, Nieves; Wärnberg, Julia; Casajús, José A; Pérez, Margarita; Aznar, Susana; Benito, Pedro J; Martínez-Gomez, David; Ortega, Francisco B; Ortega, Eduardo; Urrialde, Rafael</p> <p>2014-06-01</p> <p>Since the beginning of mankind, man has sought ways to promote and preserve health as well as to prevent disease. <span class="hlt">Hydration</span>, physical activity and exercise are key factors for enhancing human health. However, either a little dose of them or an excess can be harmful for health maintenance at any age. Water is an essential nutrient for human body and a major key to survival has been to prevent dehydration. However, there is still a general controversy regarding the necessary amount to drink water or other beverages to properly get an adequate level of <span class="hlt">hydration</span>. In addition, up to now the tools used to measure <span class="hlt">hydration</span> are controversial. To this end, there are several important groups of variables to take into account such as water balance, <span class="hlt">hydration</span> biomarkers and total body water. A combination of methods will be the most preferred tool to find out any risk or situation of dehydration at any age range. On the other hand, physical activity and exercise are being demonstrated to promote health, avoiding or reducing health problems, vascular and inflammatory disea ses and helping weight management. Therefore, physical activity is also being used as a pill within a therapy to promote health and reduce risk diseases, but as in the case of drugs, dose, intensity, frequency, duration and precautions have to be evaluated and taken into account in order to get the maximum effectiveness and success of a treatment. On the other hand, sedentariness is the opposite concept to physical activity that has been recently recognized as an important factor of lifestyle involved in the obesogenic environment and consequently in the risk of the non-communicable diseases. In view of the literature consulted and taking into account the expertise of the authors, in this review a Decalogue of global recommendations is included to achieve an adequate <span class="hlt">hydration</span> and physical activity status to avoid overweight/obesity consequences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10147399','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10147399"><span>Gas <span class="hlt">hydrate</span> reservoir characteristics and economics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S.; Bird, K.J.; Burruss, R.C.; Lee, Myung W.</p> <p>1992-06-01</p> <p>The primary objective of the DOE-funded USGS Gas <span class="hlt">Hydrate</span> Program is to assess the production characteristics and economic potential of gas <span class="hlt">hydrates</span> in northern Alaska. The objectives of this project for FY-1992 will include the following: (1) Utilize industry seismic data to assess the distribution of gas <span class="hlt">hydrates</span> within the nearshore Alaskan continental shelf between Harrison Bay and Prudhoe Bay; (2) Further characterize and quantify the well-log characteristics of gas <span class="hlt">hydrates</span>; and (3) Establish gas monitoring stations over the Eileen fault zone in northern Alaska, which will be used to measure gas flux from destabilized <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5287783','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5287783"><span>Gas <span class="hlt">hydrate</span> reservoir characteristics and economics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S.; Bird, K.J.; Burruss, R.C.; Lee, Myung W.</p> <p>1992-01-01</p> <p>The primary objective of the DOE-funded USGS Gas <span class="hlt">Hydrate</span> Program is to assess the production characteristics and economic potential of gas <span class="hlt">hydrates</span> in northern Alaska. The objectives of this project for FY-1992 will include the following: (1) Utilize industry seismic data to assess the distribution of gas <span class="hlt">hydrates</span> within the nearshore Alaskan continental shelf between Harrison Bay and Prudhoe Bay; (2) Further characterize and quantify the well-log characteristics of gas <span class="hlt">hydrates</span>; and (3) Establish gas monitoring stations over the Eileen fault zone in northern Alaska, which will be used to measure gas flux from destabilized <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6121236','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6121236"><span>Isotopic composition of a <span class="hlt">calcite</span>-cemented layer in the Lower Jurassic Bridport Sands, southern England: Implications for formation of laterally extensive <span class="hlt">calcite</span>-cemented layers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bjoerkum, P.A. ); Walderhaug, O. )</p> <p>1993-07-01</p> <p>[delta][sup 18]O[sub PDB] and [delta][sup 13]C[sub PDB] values have been measured on 107 <span class="hlt">calcite</span> cement samples from a laterally extensive (> 3 km) and continuous <span class="hlt">calcite</span>-cemented layer 0.5 m thick in the coastal exposures of the Lower Jurassic shallow-marine Bridport Sands in Dorset, southern England. The samples were taken from a two-dimensional grid with 10-cm horizontal and vertical spacing between samples and along individual vertical lines across the <span class="hlt">calcite</span>-cemented layer, [delta][sup 18]O[sub PDB] values vary between [minus]4.8% and [minus]9.2% and decrease radially outwards from points with lateral spacings on the order of 0.5-1 m in the middle of the <span class="hlt">calcite</span>-cemented layer. The [delta][sup 18]O[sub PDB] values therefore indicate that the <span class="hlt">calcite</span>-cemented layer was formed by merging of concretions. All [delta][sup 13]C[sub PDB] values measured are in the narrow range [minus]2.2% to [minus]0.5%, which suggests that the dominant source of <span class="hlt">calcite</span> cement in the layer was biogenic carbonate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22370403','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22370403"><span>Long-term field-scale experiment on using <span class="hlt">lime</span> filters in an agricultural catchment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kirkkala, Teija; Ventelä, Anne-Mari; Tarvainen, Marjo</p> <p>2012-01-01</p> <p>The River Yläneenjoki catchment in southwest Finland is an area with a high agricultural nutrient load. We report here on the nutrient removal performance of three on-site <span class="hlt">lime</span>-sand filters (F1, F2, and F3), established within or on the edge of the buffer zones. The filters contain burnt <span class="hlt">lime</span> (CaO) or spent <span class="hlt">lime</span> [CaO, Ca(OH), and CaCO]. Easily soluble <span class="hlt">lime</span> results in a high pH level (>11) and leads to an efficient precipitation of soluble phosphorus (P) from the runoff. Water samples were taken from the inflow and outflow of each site in different hydrological situations. The length of the monitoring period was 4 yr for F1, 6 yr for F2, and 1.5 yr for F3. F1 and F2 significantly reduced the suspended solids (SS), total P (PTOT), and dissolved reactive P (DRP) in the treated water. The proportional reduction (%) varied but was usually clearly positive. Filter F3 was divided into two equal parts, one containing burnt <span class="hlt">lime</span> and the other spent <span class="hlt">lime</span>. Both filter parts removed PTOT and SS efficiently from the water; the burnt-<span class="hlt">lime</span> part also removed DRP. The mixed-<span class="hlt">lime</span> part removed DRP for a year, but then the efficiency decreased. The effect of filters on nitrogen compounds varied. We conclude that sand filters incorporating <span class="hlt">lime</span> can be used together with buffer zones to reduce both P and SS load to watercourses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16288801','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16288801"><span>Speciation of heavy metals during co-composting of sewage sludge with <span class="hlt">lime</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wong, J W C; Selvam, A</p> <p>2006-05-01</p> <p>During composting the humification of organic matter will have a significant effect on the physicochemical form of existence of heavy metals. Therefore the present study was conducted to investigate the effect of co-composting sewage sludge with <span class="hlt">lime</span> on heavy metal speciation and the changes in DTPA extractable metals. Metal speciation was conducted to evaluate the redistribution of Cu, Mn, Ni, Pb and Zn in sewage sludge composted with <span class="hlt">lime</span>. Sewage sludge was mixed with sawdust in 2:1 (w/w fresh weight) and then composted with <span class="hlt">lime</span> at 0%, 0.63%, 1% or 1.63% (dry weight) for 100 days. The <span class="hlt">lime</span> addition did not cause any changes in the different forms of Cu and Mn, but the composting process caused transformations of residual form of Cu and Mn into oxidizable and reducible form, respectively. For Ni, the reducible form was mainly transformed into residual form and <span class="hlt">lime</span> addition decreased this transformation. Major transformation of different forms of Pb was not found, however the residual form of Pb increased with <span class="hlt">lime</span> addition. The predominant residual form of Zn was mainly transformed into oxidizable form and the <span class="hlt">lime</span> addition reduced this transformation. Addition of <span class="hlt">lime</span> to sewage sludge during composting resulted in lower DTPA extractable metal contents. Therefore, <span class="hlt">lime</span> is a suitable material to co-compost with sewage sludge to reduce the availability of heavy metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JCrGr.163..434G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JCrGr.163..434G"><span>Struvite and <span class="hlt">calcite</span> crystallization induced by cellular membranes of Myxococcus xanthus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>González-Muñoz, Ma Teresa; Omar, Nabil Ben; Martínez-Cañamero, Magdalena; Rodríguez-Gallego, Manuel; Galindo, Alberto López; Arias, JoséMa</p> <p>1996-06-01</p> <p>In this work we have proved that struvite and <span class="hlt">calcite</span> crystals can be obtained in the presence of the cellular membrane fraction of Myxococcus xanthus, when appropriate supersaturated solutions are used. Probably, the negative charged points of the external side of the cellular structures could reduce the metastability field of struvite and <span class="hlt">calcite</span>, acting as heterogeneous nuclei of crystallization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6458514','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6458514"><span>Carbon and oxygen isotopes in apatite CO/sub 2/ and co-existing <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kolodny, Y.; Kaplan, I. R.</p> <p>1981-04-01</p> <p>Carbon and oxygen isotopes were analyzed in carbonate apatite CO/sub 2/ and in co-existing <span class="hlt">calcite</span>. Both C and O in apatite CO/sub 2/ are enriched in the respective light isotopes relative to <span class="hlt">calcite</span>. These results confirm the proposition that carbonate is part of the apatite structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3946587','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3946587"><span>Biotic Control of Skeletal Growth by Scleractinian Corals in Aragonite–<span class="hlt">Calcite</span> Seas</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Higuchi, Tomihiko; Fujimura, Hiroyuki; Yuyama, Ikuko; Harii, Saki; Agostini, Sylvain; Oomori, Tamotsu</p> <p>2014-01-01</p> <p>Modern scleractinian coral skeletons are commonly composed of aragonite, the orthorhombic form of CaCO3. Under certain conditions, modern corals produce <span class="hlt">calcite</span> as a secondary precipitate to fill pore space. However, coral construction of primary skeletons from <span class="hlt">calcite</span> has yet to be demonstrated. We report a <span class="hlt">calcitic</span> primary skeleton produced by the modern scleractinian coral Acropora tenuis. When uncalcified juveniles were incubated from the larval stage in seawater with low mMg/Ca levels, the juveniles constructed <span class="hlt">calcitic</span> crystals in parts of the primary skeleton such as the septa; the deposits were observable under Raman microscopy. Using scanning electron microscopy, we observed different crystal morphologies of aragonite and <span class="hlt">calcite</span> in a single juvenile skeleton. Quantitative analysis using X-ray diffraction showed that the majority of the skeleton was composed of aragonite even though we had exposed the juveniles to manipulated seawater before their initial crystal nucleation and growth processes. Our results indicate that the modern scleractinian coral Acropora mainly produces aragonite skeletons in both aragonite and <span class="hlt">calcite</span> seas, but also has the ability to use <span class="hlt">calcite</span> for part of its skeletal growth when incubated in <span class="hlt">calcite</span> seas. PMID:24609012</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800060500&hterms=Cactus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCactus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800060500&hterms=Cactus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCactus"><span>Shock-induced effects in <span class="hlt">calcite</span> from Cactus Crater</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vizgirda, J.; Ahrens, T. J.; Tsay, F.-D.</p> <p>1980-01-01</p> <p>The paper discusses shock metamorphism of <span class="hlt">calcite</span> from coralline limestone samples retrieved from a borehole drilled into rocks beneath Cactus Crater, a nuclear explosion crater at Eniwetok Atoll. The metamorphism was detected and quantified using electron spin resonance (ESR); the ESR spectra of Mn(+) present as a trace constituent in the coral samples, show a consistent decrease in hyperfine peak splitting with decreasing depth of sample. It is suggested that the decrease in hyperfine peak splitting reflects a decrease in crystal field splitting, and therefore, small increases on cation-anion distances produced by mechanical energy input during the shock process. Two alternative crater models suggested by the ESR results are a depiction of a steady decay of the shock wave, and a delineation of a breccia lens with a breccia-bedrock interface at 20 plus or minus 5 m.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16240102','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16240102"><span>On the origin of fiber <span class="hlt">calcite</span> crystals in moonmilk deposits.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cañaveras, Juan Carlos; Cuezva, Soledad; Sanchez-Moral, Sergio; Lario, Javier; Laiz, Leonila; Gonzalez, Juan Miguel; Saiz-Jimenez, Cesareo</p> <p>2006-01-01</p> <p>In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber <span class="hlt">calcite</span> crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals, extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4759641','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4759641"><span><span class="hlt">Calcite</span> orientations and composition ranges within teeth across Echinoidea</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Stock, Stuart R.; Ignatiev, Konstantin; Lee, Peter L.; Almer, Jonathan D.</p> <p>2016-01-01</p> <p>Sea urchin’s teeth from four families of order Echinoida and from orders Temnopleuroida, Arbacioida and Cidaroida were studied with synchrotron x-ray diffraction. The high and very high Mg <span class="hlt">calcite</span> phases of the teeth, i.e. the first and second stage mineral constituents, respectively, have the same crystallographic orientations. The co-orientation of first and second stage mineral, which the authors attribute to epitaxy, extends across the phylogenic width of the extant regular sea urchins and demonstrates that this is a primitive character of this group. The range of compositions Δx for the two phases of Ca1−xMgxCO3 is about 0.20 or greater and is consistent with a common biomineralization process. PMID:25158180</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3788374','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3788374"><span>Structural evolution of <span class="hlt">calcite</span> at high temperatures: Phase V unveiled</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ishizawa, Nobuo; Setoguchi, Hayato; Yanagisawa, Kazumichi</p> <p>2013-01-01</p> <p>The <span class="hlt">calcite</span> form of calcium carbonate CaCO3 undergoes a reversible phase transition between Rc and Rm at ~1240 K under a CO2 atmosphere of ~0.4 MPa. The joint probability density function obtained from the single-crystal X-ray diffraction data revealed that the oxygen triangles of the CO3 group in the high temperature form (Phase V) do not sit still at specified positions in the space group Rm, but migrate along the undulated circular orbital about carbon. The present study also shows how the room temperature form (Phase I) develops into Phase V through an intermediate form (Phase IV) in the temperature range between ~985 K and ~1240 K. PMID:24084871</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMPP22B..02B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMPP22B..02B"><span>A global deglacial negative carbon isotope excursion in speleothem <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Breecker, D.</p> <p>2015-12-01</p> <p>δ13C values of speleothem <span class="hlt">calcite</span> decreased globally during the last deglaciation defining a carbon isotope excursion (CIE) despite relatively constant δ13C values of carbon in the ocean-atmosphere system. The magnitude of the CIE varied with latitude, increasing poleward from ~2‰ in the tropics to as much as 7‰ at high latitudes. This recent CIE provides an interesting comparison with CIEs observed in deep time. A substantial portion of this CIE can be explained by the increase in atmospheric pCO2 that accompanied deglaciation. The dependence of C3 plant δ13C values on atmospheric pCO2 predicts a 2‰ δ13C decrease driven by the deglacial pCO2 increase. I propose that this signal was transferred to caves and thus explains nearly 100% of the CIE magnitude observed in the tropics and no less than 30% at the highest latitudes in the compilation. An atmospheric pCO2 control on speleothem δ13C values, if real, will need to be corrected for using ice core data before δ13C records can be interpreted in a paleoclimate context. The decrease in the magnitude of the equilibrium <span class="hlt">calcite</span>-CO2 carbon isotope fractionation factor explains a maximum of 1‰ of the CIE at the highest northern latitude in the compilation, which experienced the largest deglacial warming. Much of the residual extratropical CIE was likely driven by increasing belowground respiration rates, which were presumably pronounced at high latitudes as glacial retreat exposed fresh surfaces and/or vegetation density increased. The largest increases in belowground respiration would have therefore occurred at the highest latitudes, explaining the meridional trend. This work supports the notion that increases in atmospheric pCO2 and belowground respiration rates can result in large CIEs recorded in terrestrial carbonates, which, as previously suggested, may explain the magnitude of the PETM CIE as recorded by paleosol carbonates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020061','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020061"><span>Well log evaluation of gas <span class="hlt">hydrate</span> saturations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, T.S.</p> <p>1998-01-01</p> <p>The amount of gas sequestered in gas <span class="hlt">hydrates</span> is probably enormous, but estimates are highly speculative due to the lack of previous quantitative studies. Gas volumes that may be attributed to a gas <span class="hlt">hydrate</span> accumulation within a given geologic setting are dependent on a number of reservoir parameters; one of which, gas-<span class="hlt">hydrate</span> saturation, can be assessed with data obtained from downhole well logging devices. The primary objective of this study was to develop quantitative well-log evaluation techniques which will permit the calculation of gas-<span class="hlt">hydrate</span> saturations in gas-<span class="hlt">hydrate</span>-bearing sedimentary units. The "standard" and "quick look" Archie relations (resistivity log data) yielded accurate gas-<span class="hlt">hydrate</span> and free-gas saturations within all of the gas <span class="hlt">hydrate</span> accumulations assessed in the field verification phase of the study. Compressional wave acoustic log data have been used along with the Timur, modified Wood, and the Lee weighted average acoustic equations to calculate accurate gas-<span class="hlt">hydrate</span> saturations in all of the gas <span class="hlt">hydrate</span> accumulations assessed in this study. The well log derived gas-<span class="hlt">hydrate</span> saturations calculated in the field verification phase of this study, which range from as low as 2% to as high as 97%, confirm that gas <span class="hlt">hydrates</span> represent a potentially important source of natural gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5232769','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5232769"><span>Handbook of gas <span class="hlt">hydrate</span> properties and occurrence</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kuustraa, V.A.; Hammershaimb, E.C.</p> <p>1983-12-01</p> <p>This handbook provides data on the resource potential of naturally occurring <span class="hlt">hydrates</span>, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring <span class="hlt">hydrate</span> potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of <span class="hlt">hydrates</span>, respectively. The thermodynamic properties of <span class="hlt">hydrates</span> that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of <span class="hlt">hydrate</span> dissociation. The final chapter evaluates the net energy balance of recovering <span class="hlt">hydrates</span> and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of <span class="hlt">hydrates</span>. 158 references, 67 figures, 47 tables.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/tei/0118/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/tei/0118/report.pdf"><span>The quantitative determination of <span class="hlt">calcite</span> associated with the carbonate-bearing apatites</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Silverman, Sol R.; Fuyat, Ruth K.; Weiser, Jeanne D.</p> <p>1951-01-01</p> <p>The CO2 combined as <span class="hlt">calcite</span> in carbonate-bearing apatites as been distinguished from that combined as carbonate-apatite, or present in some form other than <span class="hlt">calcite</span>, by use of X-ray powder patterns, differential thermal analyses, and differential solubility tests. These methods were applied to several pure apatite minerals, to one fossil bone, and to a group of phosphorites from the Phosphoria formation of Permian age from Trail Canyon and the Conda mine, Idaho, and the Laketown district, Utah. With the exceptions of pure fluorapatite, pure carbonate-flueorapatite, and one phosphorite from Trail Canyon, these substances contain varying amounts of <span class="hlt">calcite</span>, but in all the samples an appreciable part of the carbonite content is not present as <span class="hlt">calcite</span>. The results of solubility tests, in which the particle size of sample and the length of solution time were varied, imply that the carbonate content is not due to shielded <span class="hlt">calcite</span> entrapped along an internal network of surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1130649','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1130649"><span>Influence of <span class="hlt">calcite</span> on uranium(VI) reactive transport in the groundwater–river mixing zone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ma, Rui; Liu, Chongxuan; Greskowiak, Janek; Prommer, Henning; Zachara, John M.; Zheng, Chunmiao</p> <p>2014-01-23</p> <p><span class="hlt">Calcite</span> is an important mineral that can affect uranyl reactive transport in subsurface sediments. This study investigated the distribution of <span class="hlt">calcite</span> and its influence on uranyl adsorption and reactive transport in the groundwater-river mixing zone at US Hanford 300A, Washington State. Simulations using a 2D reactive transport model under field-relevant hydrogeochemical conditions revealed a complex distribution of <span class="hlt">calcite</span> concentration as a result of dynamic groundwater-river interactions. The <span class="hlt">calcite</span> concentration distribution in turn affected the spatial and temporal changes in aqueous carbonate, calcium, and pH, which subsequently influenced U(VI) mobility and discharge rates into the river. The results implied that <span class="hlt">calcite</span> distribution and its concentration dynamics is an important consideration for field characterization, monitoring, and reactive transport prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998SedG..116...13H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998SedG..116...13H"><span>Low limit of Mn 2+-activated cathodoluminescence of <span class="hlt">calcite</span>: state of the art</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Habermann, Dirk; Neuser, Rolf D.; Richter, Detlev K.</p> <p>1998-02-01</p> <p>In the literature, the lower limit for Mn 2+-activated cathodoluminescence (CL) of <span class="hlt">calcite</span> is variously reputed to over a very wide range of values above 10 ppm Mn. Our spectroscopic investigations of the CL response in natural <span class="hlt">calcite</span> reveal that below 10 ppm manganese content Mn 2+-activation is also present. Using the Quantitative High Resolution Spectral analysis of CL (QHRS-CL) an activation by Mn 2+ in the range of 700 ppb is proved, which cannot be determined visually. So, if not quenched, the minimum Mn 2+ content for Mn 2+-activation is one atom in the irradiated <span class="hlt">calcite</span> crystal lattice volume. As the intrinsic (background blue) luminescence is used to determine non-altered biogenic <span class="hlt">calcite</span>, the limit of Mn 2+-activation plays an important role in the interpretation of diagenetic processes. Our results of spectroscopic analyses require a revision of current opinions about the diagenesis of <span class="hlt">calcite</span> as revealed by CL investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24188740','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24188740"><span>Unusual micrometric <span class="hlt">calcite</span>-aragonite interface in the abalone shell Haliotis (Mollusca, Gastropoda).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dauphin, Yannicke; Cuif, Jean-Pierre; Castillo-Michel, Hiram; Chevallard, Corinne; Farre, Bastien; Meibom, Anders</p> <p>2014-02-01</p> <p>Species of Haliotis (abalone) show high variety in structure and mineralogy of the shell. One of the European species (Haliotis tuberculata) in particular has an unusual shell structure in which <span class="hlt">calcite</span> and aragonite coexist at a microscale with small patches of aragonite embedded in larger <span class="hlt">calcitic</span> zones. A detailed examination of the boundary between <span class="hlt">calcite</span> and aragonite using analytical microscopies shows that the organic contents of <span class="hlt">calcite</span> and aragonite differ. Moreover, changes in the chemical composition of the two minerals seem to be gradual and define a micrometric zone of transition between the two main layers. A similar transition zone has been observed between the layers in more classical and regularly structured mollusk shells. The imbrication of microscopic patches of aragonite within a <span class="hlt">calcitic</span> zone suggests the occurrence of very fast physiological changes in these taxa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JCrGr.142..156A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JCrGr.142..156A"><span>Crystal-protein interactions studied by overgrowth of <span class="hlt">calcite</span> on biogenic skeletal elements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aizenberg, J.; Albeck, S.; Weiner, S.; Addadi, L.</p> <p>1994-09-01</p> <p>A key parameter in the biological control of crystal formation is the interaction of a group of acidic macromolecules with the mineral phase. Here we study protein-<span class="hlt">calcite</span> interactions using epitaxial overgrowth of synthetic <span class="hlt">calcite</span> crystals under conditions in which local release of occluded macromolecules from the biogenic substrate occurs. The macromolecules subsequently interact with the newly formed overgrown crystals, resulting in modified <span class="hlt">calcite</span> morphology. This novel method provides a means of mapping crystal-protein interactions under conditions that minimally affect the conformational states of the acidic macromolecules. We show that proteins released from <span class="hlt">calcitic</span> sponge spicules and mollusc prisms specifically interact with {001} and {01 l} faces of <span class="hlt">calcite</span>, whereas proteins released from echinoderm skeletal elements only interact with {01 l} faces. The extent to which the overgrown crystals are affected by the proteins varies even in the same organism and within the same element, depending on the site and crystallographic orientation of the skeletal elements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25063580','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25063580"><span>Aragonite shells are more ancient than <span class="hlt">calcite</span> ones in bivalves: new evidence based on omics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Xiaotong; Li, Li; Zhu, Yabing; Song, Xiaorui; Fang, Xiaodong; Huang, Ronglian; Que, Huayong; Zhang, Guofan</p> <p>2014-11-01</p> <p>Two calcium carbonate crystal polymorphs, aragonite and <span class="hlt">calcite</span>, are the main inorganic components of mollusk shells. Some fossil evidences suggest that aragonite shell is more ancient than <span class="hlt">calcite</span> shell for the Bivalvia. But, the molecular biology evidence for the above deduction is absent. In this study, we searched for homologs of bivalve aragonite-related and <span class="hlt">calcite</span>-related shell proteins in the oyster genome, and found that no homologs of <span class="hlt">calcite</span>-related shell protein but some homologs of aragonite-related shell proteins in the oyster genome. We explained the results as the new evidence to support that aragonite shells are more ancient than <span class="hlt">calcite</span> shells in bivalves combined the published biogeological and seawater chemistry data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70157170','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157170"><span>Well log characterization of natural gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, Timothy S.; Lee, Myung W.</p> <p>2011-01-01</p> <p>In the last 25 years we have seen significant advancements in the use of downhole well logging tools to acquire detailed information on the occurrence of gas <span class="hlt">hydrate</span> in nature: From an early start of using wireline electrical resistivity and acoustic logs to identify gas <span class="hlt">hydrate</span> occurrences in wells drilled in Arctic permafrost environments to today where wireline and advanced logging-while-drilling tools are routinely used to examine the petrophysical nature of gas <span class="hlt">hydrate</span> reservoirs and the distribution and concentration of gas <span class="hlt">hydrates</span> within various complex reservoir systems. The most established and well known use of downhole log data in gas <span class="hlt">hydrate</span> research is the use of electrical resistivity and acoustic velocity data (both compressional- and shear-wave data) to make estimates of gas <span class="hlt">hydrate</span> content (i.e., reservoir saturations) in various sediment types and geologic settings. New downhole logging tools designed to make directionally oriented acoustic and propagation resistivity log measurements have provided the data needed to analyze the acoustic and electrical anisotropic properties of both highly inter-bedded and fracture dominated gas <span class="hlt">hydrate</span> reservoirs. Advancements in nuclear-magnetic-resonance (NMR) logging and wireline formation testing have also allowed for the characterization of gas <span class="hlt">hydrate</span> at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas <span class="hlt">hydrates</span> are physically distributed in sediments and the occurrence and nature of pore fluids (i.e., free-water along with clay and capillary bound water) in gas-<span class="hlt">hydrate</span>-bearing reservoirs. Information on the distribution of gas <span class="hlt">hydrate</span> at the pore scale has provided invaluable insight on the mechanisms controlling the formation and occurrence of gas <span class="hlt">hydrate</span> in nature along with data on gas <span class="hlt">hydrate</span> reservoir properties (i.e., permeabilities) needed to accurately predict gas production rates for various gas <span class="hlt">hydrate</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037061','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037061"><span>Thermal conductivity of <span class="hlt">hydrate</span>-bearing sediments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.</p> <p>2009-01-01</p> <p>A thorough understanding of the thermal conductivity of <span class="hlt">hydrate</span>-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas <span class="hlt">hydrate</span> deposits and for estimating regional heat flow based on the observed depth to the base of the gas <span class="hlt">hydrate</span> stability zone. The coexistence of multiple phases (gas <span class="hlt">hydrate</span>, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of <span class="hlt">hydrate</span>-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for <span class="hlt">hydrate</span>-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF <span class="hlt">hydrate</span>-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-<span class="hlt">hydrate</span> filled pore spaces. The thermal conductivity of THF <span class="hlt">hydrate</span>-bearing soils increases upon <span class="hlt">hydrate</span> formation although the thermal conductivities of THF solution and THF <span class="hlt">hydrate</span> are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during <span class="hlt">hydrate</span> crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to <span class="hlt">hydrate</span> formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-<span class="hlt">hydrate</span> interfaces. Copyright 2009 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRB..11411103C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRB..11411103C"><span>Thermal conductivity of <span class="hlt">hydrate</span>-bearing sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn</p> <p>2009-11-01</p> <p>A thorough understanding of the thermal conductivity of <span class="hlt">hydrate</span>-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas <span class="hlt">hydrate</span> deposits and for estimating regional heat flow based on the observed depth to the base of the gas <span class="hlt">hydrate</span> stability zone. The coexistence of multiple phases (gas <span class="hlt">hydrate</span>, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of <span class="hlt">hydrate</span>-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for <span class="hlt">hydrate</span>-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF <span class="hlt">hydrate</span>-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-<span class="hlt">hydrate</span> filled pore spaces. The thermal conductivity of THF <span class="hlt">hydrate</span>-bearing soils increases upon <span class="hlt">hydrate</span> formation although the thermal conductivities of THF solution and THF <span class="hlt">hydrate</span> are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during <span class="hlt">hydrate</span> crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to <span class="hlt">hydrate</span> formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-<span class="hlt">hydrate</span> interfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813478G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813478G"><span>The effectiveness of surface <span class="hlt">liming</span> in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Golos, Peter</p> <p>2016-04-01</p> <p>Revegetation of sites following soil contamination can be challenging especially in identifying the most effective method for ameliorating phytotoxic effects in arid ecosystems. This study at a copper mine in the Great Sandy Desert of Western Australia investigated vegetation restoration of a site contaminated by acid (H2SO4) leach pad solution. Elevated soil copper at low soil pH is phytotoxic to plant roots inhibiting root elongation. In arid ecosystems where rapid root growth is crucial for seedling survival post germination physical or chemical barriers to root growth need to be identified and ameliorated. Initial attempt at rehabilitation of contaminated site with <span class="hlt">hydrated</span> <span class="hlt">lime</span> (CaOH2) at 2 tonnes/ha followed by ripping to 30 cm depth then seeding was ineffective as successful seedling emergence was followed by over 90% seedling mortality which was 10-fold greater than seedling mortality in an uncontaminated reference site. High mortality was attributed to seedling roots being impededed as soil water was more than 3-fold greater at 5 to 40 cm depth in contaminated site than reference site. In response to high seedling mortality after emergence test pits were dug to 1 m deep to collect soil samples at 10 cm intervals for phytotoxicity testing and to measure soil pH-CaCl2, copper (DPTA ion extraction), electrical conductivity and gravimetric water content in three replicate pits at three replicate sites. Also, soil impedance was measured down the soil profile at 5 cm intervals at six replicate points/pit. For phytotoxicity testing soil samples were placed into three replicate plastic pots/sample and seeded with 10 seeds of Avena sativa and watered daily. Seedlings were harvested after at least two weeks after seedling emergence and rooting depth in pots measured. There was no difference in seedling emergence and survival of seedlings between contaminated and uncontaminated soil samples however mean seedling root growth was significantly lower in soil samples</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.159...61R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.159...61R"><span>Interactions of arsenic with <span class="hlt">calcite</span> surfaces revealed by in situ nanoscale imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Renard, François; Putnis, Christine V.; Montes-Hernandez, German; Ruiz-Agudo, Encarnacion; Hovelmann, Jörn; Sarret, Géraldine</p> <p>2015-06-01</p> <p>Arsenic dissolved in water represents a key environmental and health challenge because several million people are under the threat of contamination. In calcareous environments <span class="hlt">calcite</span> may play an important role in arsenic solubility and transfer in water. Arsenic-<span class="hlt">calcite</span> interactions remain controversial, especially for As(III) which was proposed to be either incorporated as such, or as As(V) after oxidation. Here, we provide the first time-lapse in situ study of the evolution of the (10-14) <span class="hlt">calcite</span> cleavage surface morphology during dissolution and growth in the presence of solutions with various amounts of As(III) or As(V) at room temperature and pH range 6-11 using a flow-through cell connected to an atomic force microscope (AFM). Reaction products were then characterized by Raman spectroscopy. In parallel, co-precipitation experiments with either As(III) or As(V) were performed in batch reactors, and the speciation of arsenic in the resulting solids was studied by X-ray absorption spectroscopy (XAS). For As(V), AFM results showed that it interacts strongly with the <span class="hlt">calcite</span> surface, and XAS results showed that As(V) was mostly incorporated in the <span class="hlt">calcite</span> structure. For As(III), AFM results showed much less impact on <span class="hlt">calcite</span> growth and dissolution and less incorporation was observed. This was confirmed by XAS results that indicate that As(III) was partly oxidized into As(V) before being incorporated into <span class="hlt">calcite</span> and the resulting <span class="hlt">calcite</span> contained 36% As(III) and 64% As(V). All these experimental results confirm that As(V) has a much stronger interaction with <span class="hlt">calcite</span> than As(III) and that <span class="hlt">calcite</span> may represent an important reservoir for arsenic in various geological environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20006591','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20006591"><span>Diel cycles in <span class="hlt">calcite</span> production and dissolution in a eutrophic basin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cicerone, D.S.; Stewart, A.J.; Roh, Y.</p> <p>1999-10-01</p> <p><span class="hlt">Calcite</span> production is understood largely as a longer-term phenomenon (e.g., seasonal whitings) that can occur in hardwater lakes, and is significant ecologically because it can slow the rate of eutrophication by reducing, through adsorption, the availability of nutrients to primary producers. In this study the authors show that rapid changes in concentration of dissolved CO{sub 2} by photosynthesis and respiration within a eutrophic basin generated strong day-to-night cycles in <span class="hlt">calcite</span> production and dissolution. Diel cycles in <span class="hlt">calcite</span> production and dissolution were large enough that they could drive secondary diel cycles in the availability of metals that strongly sorb to the surfaces of <span class="hlt">calcite</span> particles. They explored the possibility of the secondary diel cycling of metals by intensive 7-d in situ monitoring of water-quality conditions in a shallow, eutrophic spill-control basin near an industrial facility in eastern Tennessee; inspecting data from a 7-year record of water-quality parameters for this basin; analyzing physicochemical characteristics and mineralogic composition of sediments in the basin; and conducting laboratory experiments to characterize the interaction of <span class="hlt">calcite</span> with Cd, under solid-liquid nonequilibrium conditions. The authors found that the basin accumulated and stored <span class="hlt">calcite</span>. In situ monitoring showed that <span class="hlt">calcite</span> was produced during daylight, and tended to dissolve again at night; the <span class="hlt">calcite</span> production and dissolution processes seemed to be modulated by dissolved-phase CO{sub 2} dynamics, in concert with large diel fluctuations in pCa, pH, and Po{sub 2}. Laboratory experiments showed a rapid interaction ({lt}6 h) of Cd with <span class="hlt">calcite</span>, in response to dissolved CO{sub 2} changes. Thus, concentrations of dissolved Cd can vary over daily cycles, mediated by diel changes in <span class="hlt">calcite</span> production and dissolution. Thermodynamic considerations suggest that other metals, such as Zn, Sr, Ni, and Ba, may demonstrate this behavior as well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006Geo....34..525R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006Geo....34..525R"><span>Scleractinian corals produce <span class="hlt">calcite</span>, and grow more slowly, in artificial Cretaceous seawater</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ries, Justin B.; Stanley, Steven M.; Hardie, Lawrence A.</p> <p>2006-07-01</p> <p>The mineralogies of most biotic and abiotic carbonates have alternated in synchroneity between the <span class="hlt">calcite</span> (hexagonal) and aragonite (orthorhombic) polymorphs of CaCO3 throughout the Phanerozoic Eon. These intervals of <span class="hlt">calcite</span> and aragonite production, or <span class="hlt">calcite</span> seas and aragonite seas, are thought to be caused primarily by secular variation in the molar magnesium/calcium ratio of seawater (m</em>Mg/Ca > 2 = aragonite + high-Mg <span class="hlt">calcite</span>; m</em>Mg/Ca < 2 = low-Mg <span class="hlt">calcite</span>), a ratio that has oscillated between 1.0 and 5.2 throughout the Phanerozoic. In laboratory experiments, we show that three species of scleractinian corals, which produce aragonite in modern seawater and which have flourished as important reef builders primarily during aragonite seas of the past, began producing <span class="hlt">calcite</span> in artificial seawater with an ambient m</em>Mg/Ca ratio below that of modern seawater (5.2). The corals produced progressively higher percentages of <span class="hlt">calcite</span> and calcified at lower rates with further reduction of the ambient m</em>Mg/Ca ratio. In artificial seawater of imputed Late Cretaceous composition (m</em>Mg/Ca = 1.0), which favors the precipitation of the <span class="hlt">calcite</span> polymorph, scleractinian corals produced skeletons containing >30% low-Mg <span class="hlt">calcite</span> (skeletal m</em>Mg/Ca < 0.04). These results indicate that the skeletal mineral used by scleractinian corals is partially determined by seawater chemistry. Furthermore, slow calcification rates, resulting from the production of largely aragonitic skeletons in chemically unfavorable seawater (m</em>Mg/Ca < 2), probably contributed to the scleractinians' diminished reef-building role in the <span class="hlt">calcite</span> seas of Late Cretaceous and early Cenozoic time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JSG....70..200K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JSG....70..200K"><span>The mechanical and microstructural behaviour of <span class="hlt">calcite</span>-dolomite composites: An experimental investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kushnir, Alexandra R. L.; Kennedy, L. A.; Misra, Santanu; Benson, Philip; White, J. C.</p> <p>2015-01-01</p> <p>The styles and mechanisms of deformation associated with many variably dolomitized limestone shear systems are strongly controlled by strain partitioning between dolomite and <span class="hlt">calcite</span>. Here, we present experimental results from the deformation of four composite materials designed to address the role of dolomite on the strength of limestone. Composites were synthesized by hot isostatic pressing mixtures of dolomite (Dm) and <span class="hlt">calcite</span> powders (% Dm: 25%-Dm, 35%-Dm, 51%-Dm, and 75%-Dm). In all composites, <span class="hlt">calcite</span> is finer grained than dolomite. The synthesized materials were deformed in torsion at constant strain rate (3 × 10-4 and 1 × 10-4 s-1), high effective pressure (262 MPa), and high temperature (750 °C) to variable finite shear strains. Mechanical data show an increase in yield strength with increasing dolomite content. Composites with <75% dolomite (the remaining being <span class="hlt">calcite</span>), accommodate significant shear strain at much lower shear stresses than pure dolomite but have significantly higher yield strengths than anticipated for 100% <span class="hlt">calcite</span>. The microstructure of the fine-grained <span class="hlt">calcite</span> suggests grain boundary sliding, accommodated by diffusion creep and dislocation glide. At low dolomite concentrations (i.e. 25%), the presence of coarse-grained dolomite in a micritic <span class="hlt">calcite</span> matrix has a profound effect on the strength of composite materials as dolomite grains inhibit the superplastic flow of <span class="hlt">calcite</span> aggregates. In high (>50%) dolomite content samples, the addition of 25% fine-grained <span class="hlt">calcite</span> significantly weakens dolomite, such that strain can be partially localized along narrow ribbons of fine-grained <span class="hlt">calcite</span>. Deformation of dolomite grains by shear fracture is observed; there is no intracrystalline deformation in dolomite irrespective of its relative abundance and finite shear strain.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRB..119.2679S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRB..119.2679S"><span>Pockmark formation and evolution in deep water Nigeria: Rapid <span class="hlt">hydrate</span> growth versus slow <span class="hlt">hydrate</span> dissolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sultan, N.; Bohrmann, G.; Ruffine, L.; Pape, T.; Riboulot, V.; Colliat, J.-L.; De Prunelé, A.; Dennielou, B.; Garziglia, S.; Himmler, T.; Marsset, T.; Peters, C. A.; Rabiu, A.; Wei, J.</p> <p>2014-04-01</p> <p>In previous works, it has been suggested that dissolution of gas <span class="hlt">hydrate</span> can be responsible for pockmark formation and evolution in deep water Nigeria. It was shown that those pockmarks which are at different stages of maturation are characterized by a common internal architecture associated to gas <span class="hlt">hydrate</span> dynamics. New results obtained by drilling into gas <span class="hlt">hydrate</span>-bearing sediments with the MeBo seafloor drill rig in concert with geotechnical in situ measurements and pore water analyses indicate that pockmark formation and evolution in the study area are mainly controlled by rapid <span class="hlt">hydrate</span> growth opposed to slow <span class="hlt">hydrate</span> dissolution. On one hand, positive temperature anomalies, free gas trapped in shallow microfractures near the seafloor and coexistence of free gas and gas <span class="hlt">hydrate</span> indicate rapid <span class="hlt">hydrate</span> growth. On the other hand, slow <span class="hlt">hydrate</span> dissolution is evident by low methane concentrations and almost constant sulfate values 2 m above the Gas <span class="hlt">Hydrate</span> Occurrence Zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16268712','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16268712"><span>Search for memory effects in methane <span class="hlt">hydrate</span>: structure of water before <span class="hlt">hydrate</span> formation and after <span class="hlt">hydrate</span> decomposition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Buchanan, Piers; Soper, Alan K; Thompson, Helen; Westacott, Robin E; Creek, Jefferson L; Hobson, Greg; Koh, Carolyn A</p> <p>2005-10-22</p> <p>Neutron diffraction with HD isotope substitution has been used to study the formation and decomposition of the methane clathrate <span class="hlt">hydrate</span>. Using this atomistic technique coupled with simultaneous gas consumption measurements, we have successfully tracked the formation of the sI methane <span class="hlt">hydrate</span> from a water/gas mixture and then the subsequent decomposition of the <span class="hlt">hydrate</span> from initiation to completion. These studies demonstrate that the application of neutron diffraction with simultaneous gas consumption measurements provides a powerful method for studying the clathrate <span class="hlt">hydrate</span> crystal growth and decomposition. We have also used neutron diffraction to examine the water structure before the <span class="hlt">hydrate</span> growth and after the <span class="hlt">hydrate</span> decomposition. From the neutron-scattering curves and the empirical potential structure refinement analysis of the data, we find that there is no significant difference between the structure of water before the <span class="hlt">hydrate</span> formation and the structure of water after the <span class="hlt">hydrate</span> decomposition. Nor is there any significant change to the methane <span class="hlt">hydration</span> shell. These results are discussed in the context of widely held views on the existence of memory effects after the <span class="hlt">hydrate</span> decomposition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvB..92o5412F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvB..92o5412F"><span>Mechanism of atomic force microscopy imaging of three-dimensional <span class="hlt">hydration</span> structures at a solid-liquid interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukuma, Takeshi; Reischl, Bernhard; Kobayashi, Naritaka; Spijker, Peter; Canova, Fillippo Federici; Miyazawa, Keisuke; Foster, Adam S.</p> <p>2015-10-01</p> <p>Here we present both subnanometer imaging of three-dimensional (3D) <span class="hlt">hydration</span> structures using atomic force microscopy (AFM) and molecular dynamics simulations of the <span class="hlt">calcite</span>-water interface. In AFM, by scanning the 3D interfacial space in pure water and recording the force on the tip, a 3D force image can be produced, which can then be directly compared to the simulated 3D water density and forces on a model tip. Analyzing in depth the resemblance between experiment and simulation as a function of the tip-sample distance allowed us to clarify the contrast mechanism in the force images and the reason for their agreement with water density distributions. This work aims to form the theoretical basis for AFM imaging of <span class="hlt">hydration</span> structures and enables its application to future studies on important interfacial processes at the molecular scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1752d0025S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1752d0025S"><span><span class="hlt">Hydration</span> of blended cement pastes containing waste ceramic powder as a function of age</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scheinherrová, Lenka; Trník, Anton; Kulovaná, Tereza; Pavlík, Zbyšek; Rahhal, Viviana; Irassar, Edgardo F.; Černý, Robert</p> <p>2016-07-01</p> <p>The production of a cement binder generates a high amount of CO2 and has high energy consumption, resulting in a very adverse impact on the environment. Therefore, use of pozzolana active materials in the concrete production leads to a decrease of the consumption of cement binder and costs, especially when some type of industrial waste is used. In this paper, the <span class="hlt">hydration</span> of blended cement pastes containing waste ceramic powder from the Czech Republic and Portland cement produced in Argentina is studied. A cement binder is partially replaced by 8 and 40 mass% of a ceramic powder. These materials are compared with an ordinary cement paste. All mixtures are prepared with a water/cement ratio of 0.5. Thermal characterization of the <span class="hlt">hydrated</span> blended pastes is carried out in the time period from 2 to 360 days. Simultaneous DSC/TG analysis is performed in the temperature range from 25 °C to 1000 °C in an argon atmosphere. Using this thermal analysis, we identify the temperature, enthalpy and mass changes related to the liberation of physically bound water, calcium-silicate-<span class="hlt">hydrates</span> gels dehydration, portlandite, vaterite and <span class="hlt">calcite</span> decomposition and their changes during the curing time. Based on thermogravimetry results, we found out that the portlandite content slightly decreases with time for all blended cement pastes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24555321','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24555321"><span>Forest <span class="hlt">liming</span> increases forest floor carbon and nitrogen stocks in a mixed hardwood forest.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Melvin, April M; Lichstein, Jeremy W; Goodale, Christine L</p> <p>2013-12-01</p> <p>In acid-impacted forests, decreased soil pH and calcium (Ca) availability have the potential to influence biotic and abiotic controls on carbon (C) and nitrogen (N) cycling. We investigated the effects of <span class="hlt">liming</span> on above- and belowground C and N pools and fluxes 19 years after <span class="hlt">lime</span> addition to the Woods Lake Watershed, Adirondack Park, New York, USA. Soil pH and exchangeable Ca remained elevated in the forest floor and upper mineral soil of <span class="hlt">limed</span> areas. Forest floor C and N stocks were significantly larger in <span class="hlt">limed</span> plots (68 vs. 31 Mg C/ha, and 3.0 vs. 1.5 Mg N/ha), resulting from a larger mass of Oa material. <span class="hlt">Liming</span> reduced soil basal respiration rates by 17% and 43% in the Oe and Oa horizons, respectively. Net N mineralization was significantly lower in the <span class="hlt">limed</span> soils for both forest floor horizons. Additional measurements of forest floor depth outside of our study plots, but within the treatment and control subcatchments also showed a deeper forest floor in <span class="hlt">limed</span> areas; however, the mean depth of <span class="hlt">limed</span> forest floor was 5 cm shallower than that observed in our study plots. Using a differential equation model of forest floor C dynamics, we found that <span class="hlt">liming</span> effects on C fluxes measured within our study plots could explain the small observed increase in the Oe C stock but were not large enough to explain the increase in the Oa. Our catchment-wide assessment of forest floor depth, however, indicates that our plot analysis may be an overestimate of ecosystem-scale C and N stocks. Our results suggest that the mechanisms identified in our study, primarily <span class="hlt">liming</span>-induced reduction in decomposition rates, may account for much of the observed increase in forest floor C. These findings emphasize the importance of understanding of the effects of <span class="hlt">liming</span> in hardwood forests, and the long-term impacts of acid deposition on forest C and N uptake and retention.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6806245','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6806245"><span>Capital costs of <span class="hlt">lime</span> treatment at the Augusta wastewater treatment plant</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Halverson, N.V.</p> <p>1988-08-17</p> <p>The capital costs were estimated for the addition of <span class="hlt">lime</span> treatment facilities to the Augusta sewage treatment plant as a means of reducing the phosphorus loading of L Lake and consequently reducing the algae populations in the lake. Primary <span class="hlt">lime</span> treatments and tertiary <span class="hlt">lime</span> treatments were considered. The capital cost of a primary <span class="hlt">lime</span> treatment addition would be lower than for a tertiary treatment addition. Depending on whether the existing primary settling tank can be utilized for <span class="hlt">lime</span> treatment or a new clarifier must be built, a primary <span class="hlt">lime</span> treatment addition would currently cost between $500,000 and $3 million to construct at the Augusta sewage treatment plant. Primary <span class="hlt">lime</span> treatment coupled with the existing activated sludge biological treatment system would remove approximately 80% of the phosphorus from the sewage entering the sewage treatment plant, resulting in an effluent concentration of about 2 mg/l. To reduce effluent phosphorus concentration to 1 mg/l or less, additional coagulation and effluent filtration facilities would be necessary. One disadvantage of primary <span class="hlt">lime</span> treatment, however, would be the two-fold or three-fold increase in sludge to be disposed. Tertiary <span class="hlt">lime</span> treatment usually results in lower effluent phosphorus levels than primary <span class="hlt">lime</span> treatment, but the capital cost is significantly higher. Costs for tertiary <span class="hlt">lime</span> treatment for the Augusta sewage treatment plant would range from $5 million to $14 million. The higher estimate would include an additional settling stage and filtration of the effluent, features which would improve the efficiency of phosphorus removal and reduce the effluent phosphorus concentration. 12 refs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22004115','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22004115"><span>Improvement in hardness of soda-<span class="hlt">lime</span>-silica glass</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chakraborty, Riya; De, Moumita; Roy, Sudakshina; Dey, Arjun; Biswas, Sampad K.; Middya, Tapas Ranjan; Mukhopadhyay, Anoop K.</p> <p>2012-06-05</p> <p>Hardness is a key design parameter for structural application of brittle solids like glass. Here we report for the first time the significant improvement of about 10% in Vicker's hardness of a soda-<span class="hlt">lime</span>-silica glass with loading rate in the range of 0.1-10 N.s{sup -1}. Corroborative dark field optical and scanning electron microscopy provided clue to this improvement through evidence of variations in spatial density of shear deformation band formation as a function of loading rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6892408','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6892408"><span><span class="hlt">Lime</span> and fly ash stabilization of wastewater treatment sludge</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Burns, H.; Gremminger, L.</p> <p>1994-01-11</p> <p>This invention provides a process meeting the EPA's PFRP standard for WWTS treatment thereby producing a readily usable end-product in either soil-like form or semi-impermeable low load bearing, mass form. The process includes mixing WWTS with <span class="hlt">lime</span> and fly ash, to cause a temperature increase to above 70 C for at least 30 minutes and to cause the pH to exceed 12 for at least 2 hours. The end-product may be compacted to produce an semi-impermeable, durable mass or the soil-like product may be used as landfill cover material. 3 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70013156','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70013156"><span>Santaclaraite, a new calcium-manganese silicate <span class="hlt">hydrate</span> from California.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Erd, Richard C.; Ohashi, Y.</p> <p>1984-01-01</p> <p>Santaclaraite, ideally CaMn4(Si5O14(OH))(OH).H2O, occurs as pink and tan veins and masses in Franciscan chert in the Diablo Range, Santa Clara and Stanislaus counties, California. It is associated with four unidentified Mn silicates, Mn-howieite, quartz, braunite, <span class="hlt">calcite</span>, rhodochrosite, kutnahorite, baryte, harmotome, chalcopyrite and native copper. Santaclaraite is triclinic, space group B1, a 15.633(1), b 7.603(1) , c 12.003(1) A, alpha 109.71(1)o, beta 88.61(1)o, gamma 99.95(1) o, V 1322.0(3) A3; Z = 4. The strongest lines of the X-ray pattern are 7.04(100), 3.003(84), 3.152(80), 7.69(63), 3.847(57) A. Crystals are lamellar to prismatic (flattened on (100)), with good cleavage on (100) and (010); H. 61/2 Dcalc. 3.398 g/cm3, Dmeas. 3.31 (+ or -0.01); optically biaxial negative, alpha 1.681, beta 1.696, gamma 1.708 (all + or - 0.002), 2Valpha 83 (+ or -1)o. Although chemically a <span class="hlt">hydrated</span> rhodonite, santaclaraite dehydrates to Mn-bustamite at approx 550oC (in air) . Santaclaraite is a five-tetrahedral-repeat single-chain silicate and has structural affinities with rhodonite, nambulite, marsturite, babingtonite and inesite.-J.A.Z.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/860281','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/860281"><span>STRONTIUM ISOTOPE EVOLUTION OF PORE WATER AND <span class="hlt">CALCITE</span> IN THE TOPOPAH SPRING TUFF, YUCCA MOUNTAIN , NEVADA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>B.D. Marshall; K. Futa</p> <p>2001-02-07</p> <p>Yucca Mountain, a ridge of Miocene volcanic rocks in southwest Nevada, is being characterized as a site for a potential high-level radioactive waste repository. One issue of concern for the future performance of the potential repository is the movement of water in and around the potential repository horizon. Past water movement in this unsaturated zone is indicated by fluid inclusions trapped in <span class="hlt">calcite</span> coatings on fracture footwall surfaces and in some lithophysal cavities. Some of the fluid inclusions have homogenization temperatures above the present-day geotherm (J.F. Whelan, written communication), so determining the ages of the <span class="hlt">calcite</span> associated with those fluid inclusions is important in understanding the thermal history of the potential repository site. <span class="hlt">Calcite</span> ages have been constrained by uranium-lead dating of silica polymorphs (opal and chalcedony) that are present in most coatings. The opal and chalcedony ages indicate that deposition of the <span class="hlt">calcite</span> and opal coatings in the welded part of the Topopah Spring Tuff (TSw hydrogeologic unit) spanned nearly the entire history of the 12.8-million-year-old rock mass at fairly uniform overall long-term rates of deposition (within a factor of five). Constraining the age of a layer of <span class="hlt">calcite</span> associated with specific fluid inclusions is complicated. <span class="hlt">Calcite</span> is commonly bladed with complex textural relations, and datable opal or chalcedony may be millions of years older or younger than the <span class="hlt">calcite</span> layer or may be absent from the coating entirely. Therefore, a more direct method of dating the <span class="hlt">calcite</span> is presented in this paper by developing a model for strontium evolution in pore water in the TSw as recorded by the strontium coprecipitated with calcium in the <span class="hlt">calcite</span>. Although the water that precipitated the <span class="hlt">calcite</span> in fractures and cavities may not have been in local isotopic equilibrium with the pore water, the strontium isotope composition of all water in the TSw is primarily controlled by water</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/865585','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/865585"><span>Gas <span class="hlt">hydrate</span> cool storage system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ternes, Mark P.; Kedl, Robert J.</p> <p>1985-01-01</p> <p>This invention is a process for formation of a gas <span class="hlt">hydrate</span> to be used as a cool storage medium using a refrigerant in water. Mixing of the immiscible refrigerant and water is effected by addition of a surfactant and agitation. The difficult problem of subcooling during the process is overcome by using the surfactant and agitation and performance of the process significantly improves and approaches ideal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020173','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020173"><span>Well log evaluation of gas <span class="hlt">hydrate</span> saturations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, Timothy S.</p> <p>1998-01-01</p> <p>The amount of gas sequestered in gas <span class="hlt">hydrates</span> is probably enormous, but estimates are highly speculative due to the lack of previous quantitative studies. Gas volumes that may be attributed to a gas <span class="hlt">hydrate</span> accumulation within a given geologic setting are dependent on a number of reservoir parameters; one of which, gas-<span class="hlt">hydrate</span> saturation, can be assessed with data obtained from downhole well logging devices. The primary objective of this study was to develop quantitative well-log evaluation techniques which will permit the calculation of gas-<span class="hlt">hydrate</span> saturations in gas-<span class="hlt">hydrate</span>-bearing sedimentary units. The `standard' and `quick look' Archie relations (resistivity log data) yielded accurate gas-<span class="hlt">hydrate</span> and free-gas saturations within all of the gas <span class="hlt">hydrate</span> accumulations assessed in the field verification phase of the study. Compressional wave acoustic log data have been used along with the Timur, modified Wood, and the Lee weighted average acoustic equations to calculate accurate gas-<span class="hlt">hydrate</span> saturations in this study. The well log derived gas-<span class="hlt">hydrate</span> saturations calculated in the field verification phase of this study, which range from as low as 2% to as high as 97%, confirm that gas <span class="hlt">hydrates</span> represent a potentially important source of natural gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7250610','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/7250610"><span>Multiple stage multiple filter <span class="hlt">hydrate</span> store</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bjorkman, H.K. Jr.</p> <p>1983-05-31</p> <p>An improved <span class="hlt">hydrate</span> store for a metal halogen battery system is disclosed which employs a multiple stage, multiple filter means for separating the halogen <span class="hlt">hydrate</span> from the liquid used in forming the <span class="hlt">hydrate</span>. The filter means is constructed in the form of three separate sections which combine to substantially cover the interior surface of the store container. Exit conduit means is provided in association with the filter means for transmitting liquid passing through the filter means to a <span class="hlt">hydrate</span> former subsystem. The <span class="hlt">hydrate</span> former subsystem combines the halogen gas generated during the charging of the battery system with the liquid to form the <span class="hlt">hydrate</span> in association with the store. Relief valve means is interposed in the exit conduit means for controlling the operation of the separate sections of the filter means, such that the liquid flow through the exit conduit means from each of the separate sections is controlled in a predetermined sequence. The three separate sections of the filter means operate in three discrete stages to provide a substantially uniform liquid flow to the <span class="hlt">hydrate</span> former subsystem during the charging of the battery system. The separation of the liquid from the <span class="hlt">hydrate</span> causes an increase in the density of the <span class="hlt">hydrate</span> by concentrating the <span class="hlt">hydrate</span> along the filter means. 7 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864568','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864568"><span>Multiple stage multiple filter <span class="hlt">hydrate</span> store</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bjorkman, Jr., Harry K.</p> <p>1983-05-31</p> <p>An improved <span class="hlt">hydrate</span> store for a metal halogen battery system is disclosed which employs a multiple stage, multiple filter means or separating the halogen <span class="hlt">hydrate</span> from the liquid used in forming the <span class="hlt">hydrate</span>. The filter means is constructed in the form of three separate sections which combine to substantially cover the interior surface of the store container. Exit conduit means is provided in association with the filter means for transmitting liquid passing through the filter means to a <span class="hlt">hydrate</span> former subsystem. The <span class="hlt">hydrate</span> former subsystem combines the halogen gas generated during the charging of the battery system with the liquid to form the <span class="hlt">hydrate</span> in association with the store. Relief valve means is interposed in the exit conduit means for controlling the operation of the separate sections of the filter means, such that the liquid flow through the exit conduit means from each of the separate sections is controlled in a predetermined sequence. The three separate sections of the filter means operate in three discrete stages to provide a substantially uniform liquid flow to the <span class="hlt">hydrate</span> former subsystem during the charging of the battery system. The separation of the liquid from the <span class="hlt">hydrate</span> causes an increase in the density of the <span class="hlt">hydrate</span> by concentrating the <span class="hlt">hydrate</span> along the filter means.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70019143','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70019143"><span>Gas <span class="hlt">hydrate</span> resources of northern Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Collett, T.S.</p> <p>1997-01-01</p> <p>Large amounts of natural gas, composed mainly of methane, can occur in arctic sedimentary basins in the form of gas <span class="hlt">hydrates</span> under appropriate temperature and pressure conditions. Gas <span class="hlt">hydrates</span> are solids, composed of rigid cages of water molecules that trap molecules of gas. These substances are regarded as a potential unconventional source of natural gas because of their enormous gas-storage capacity. Most published gas <span class="hlt">hydrate</span> resource estimates are highly simplified and based on limited geological data. The gas <span class="hlt">hydrate</span> resource assessment for northern Alaska presented in this paper is based on a "play analysis" scheme, in which geological factors controlling the accumulation and preservation of gas <span class="hlt">hydrates</span> are individually evaluated and risked for each <span class="hlt">hydrate</span> play. This resource assessment identified two gas <span class="hlt">hydrate</span> plays; the in-place gas resources within the gas <span class="hlt">hydrates</span> of northern Alaska are estimated to range from 6.7 to 66.8 trillion cubic metres of gas (236 to 2,357 trillion cubic feet of gas), at the 0.50 and 0.05 probability levels respectively. The mean in-place <span class="hlt">hydrate</span> resource estimate for northern Alaska is calculated to be 16.7 trillion cubic metres of gas (590 trillion cubic feet of gas). If this assessment is valid, the amount of natural gas stored as gas <span class="hlt">hydrates</span> in northern Alaska could be almost seven times larger then the estimated total remaining recoverable conventional natural gas resources in the entire United States.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6746308','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6746308"><span>Gas <span class="hlt">hydrates</span>: Technology status report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1987-01-01</p> <p>In 1983, the US Department of Energy (DOE) assumed the responsibility for expanding the knowledge base and for developing methods to recover gas from <span class="hlt">hydrates</span>. These are ice-like mixtures of gas and water where gas molecules are trapped within a framework of water molecules. This research is part of the Unconventional Gas Recovery (UGR) program, a multidisciplinary effort that focuses on developing the technology to produce natural gas from resources that have been classified as unconventional because of their unique geologies and production mechanisms. Current work on gas <span class="hlt">hydrates</span> emphasizes geological studies; characterization of the resource; and generic research, including modeling of reservoir conditions, production concepts, and predictive strategies for stimulated wells. Complementing this work is research on in situ detection of <span class="hlt">hydrates</span> and field tests to verify extraction methods. Thus, current research will provide a comprehensive technology base from which estimates of reserve potential can be made, and from which industry can develop recovery strategies. 7 refs., 3 figs., 6 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22223374','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22223374"><span>Characterization of non-stoichiometric <span class="hlt">hydration</span> and the dehydration behavior of sitafloxacin <span class="hlt">hydrate</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suzuki, Tetsuya; Araki, Tetsuya; Kitaoka, Hiroaki; Terada, Katsuhide</p> <p>2012-01-01</p> <p>Sitafloxacin (STFX) <span class="hlt">hydrate</span> is a non-stoichiometric <span class="hlt">hydrate</span>. The <span class="hlt">hydration</span> state of STFX <span class="hlt">hydrate</span> varies non-stoichiometrically depending on the relative humidity and temperature, though X-ray powder diffraction (XRPD) of STFX <span class="hlt">hydrate</span> was not affected by storing at low and high relative humidities. The detailed properties of crystalline water of STFX <span class="hlt">hydrate</span> were estimated in terms of hygroscopicity, thermal analysis combined with X-ray powder diffractometry, crystallography and density functional theory (DFT) calculation. STFX <span class="hlt">hydrate</span> changed the water contents continuously and reversibly from an equivalent amount of dihydrate through that of sesquihydrate depending on the relative humidity at 25°C. Thermal analysis and X-ray powder diffraction (XRPD) simultaneous measurement also revealed that STFX <span class="hlt">hydrate</span> dehydrated into a <span class="hlt">hydrated</span> state equivalent to monohydrate by heating up to 100°C, whereas XRPD patterns were slightly affected. This indicated that the crystal structure of STFX <span class="hlt">hydrate</span> was retained at the dehydration level of monohydrate. Single-crystal X-ray structural analysis showed that two STFX molecules and four water molecule sites were contained in an asymmetric unit. STFX molecules formed a channel structure where water molecules were included. At the partially dehydrated state, at least two of four water molecules were considered to be disordered in occupancy and/or coordinates. Insight into the crystal structure of STFX <span class="hlt">hydrate</span> stored at low and high relative humidities and geometry of the hydrogen bond were helpful to estimate the origin of non-stoichiometric <span class="hlt">hydration</span> of STFX <span class="hlt">hydrate</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=316875','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=316875"><span>Substrate pH and butterfly bush response to dolomitic <span class="hlt">lime</span> or steel slag amendment</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Steel slag is a fertilizer amendment with a high concentration of calcium oxide, and thus capable of raising substrate pH similar to dolomitic <span class="hlt">lime</span>. Steel slag, however, contains higher concentrations of some nutrients, such as iron, manganese, and silicon, compared to dolomitic <span class="hlt">lime</span>. The objectiv...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3386234','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3386234"><span>Effects of <span class="hlt">Liming</span> on Forage Availability and Nutrient Content in a Forest Impacted by Acid Rain</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pabian, Sarah E.; Ermer, Nathan M.; Tzilkowski, Walter M.; Brittingham, Margaret C.</p> <p>2012-01-01</p> <p>Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus) and other forest herbivores. <span class="hlt">Liming</span> is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before <span class="hlt">liming</span> and up to 5 years post-<span class="hlt">liming</span> on 2 treated and 2 untreated 100-ha sites. Before <span class="hlt">liming</span>, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of <span class="hlt">liming</span> on forb biomass, with a 2.7 fold increase on <span class="hlt">limed</span> sites, but no biomass response in other vegetation groups. We observed positive effects of <span class="hlt">liming</span> on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to <span class="hlt">liming</span> by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer. PMID:22761890</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22761890','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22761890"><span>Effects of <span class="hlt">liming</span> on forage availability and nutrient content in a forest impacted by acid rain.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pabian, Sarah E; Ermer, Nathan M; Tzilkowski, Walter M; Brittingham, Margaret C</p> <p>2012-01-01</p> <p>Acidic deposition and subsequent forest soil acidification and nutrient depletion can affect negatively the growth, health and nutrient content of vegetation, potentially limiting the availability and nutrient content of forage for white-tailed deer (Odocoileus virginianus) and other forest herbivores. <span class="hlt">Liming</span> is a mitigation technique that can be used to restore forest health in acidified areas, but little is known about how it affects the growth or nutrient content of deer forage. We examined the effects of dolomitic limestone application on the growth and chemical composition of understory plants in an acidified forest in central Pennsylvania, with a focus on vegetative groups included as white-tailed deer forage. We used a Before-After-Control-Impact study design with observations 1 year before <span class="hlt">liming</span> and up to 5 years post-<span class="hlt">liming</span> on 2 treated and 2 untreated 100-ha sites. Before <span class="hlt">liming</span>, forage availability and several nutrients were below levels considered optimal for white-tailed deer, and many vegetative characteristics were related to soil chemistry. We observed a positive effect of <span class="hlt">liming</span> on forb biomass, with a 2.7 fold increase on <span class="hlt">limed</span> sites, but no biomass response in other vegetation groups. We observed positive effects of <span class="hlt">liming</span> on calcium and magnesium content and negative effects on aluminum and manganese content of several plant groups. Responses to <span class="hlt">liming</span> by forbs and plant nutrients show promise for improving vegetation health and forage quality and quantity for deer.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2214126','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2214126"><span>[Liquid crystal thermography; a reliable method for detecting soda <span class="hlt">lime</span> exhaustion].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tsuchiya, M; Ueda, W; Tomoda, M; Takimoto, E; Furuno, K; Kuzume, Y; Kanaya, H; Hasegawa, T; Aono, J; Maesako, M</p> <p>1990-07-01</p> <p>The dynamic and functional state of soda <span class="hlt">lime</span> can be more precisely assessed by measuring changes in wall temperatures of the absorption chambers rather than observing color change of the soda <span class="hlt">lime</span> granules. We demonstrated in this report that the liquid crystal thermometer is an inexpensive and reliable measuring device for this purpose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=308563','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=308563"><span>Molecular characterization and pathogenicity assays of Colletotrichum acutatum, causal agent for <span class="hlt">lime</span> anthracnose in Texas</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Several distorted Mexican <span class="hlt">lime</span> [Citrus aurantiifolia (Christm). Swingle] fruit, leaf, and twig samples with <span class="hlt">lime</span> anthracnose symptoms were collected from three trees in residential areas of Brownsville, Texas. The causal fungal organism, Colletotrichum acutatum J. H. Simmonds was isolated from leave...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20772437','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20772437"><span>Barley seedling growth in soils amended with fly ash or agricultural <span class="hlt">lime</span> followed by acidification</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Renken, R.R.; McCallister, D.L.; Tarkalson, D.D.; Hergert, G.W.; Marx, D.B.</p> <p>2006-05-15</p> <p>Calcium-rich coal combustion fly ash can be used as an amendment to neutralize soil acidity because of its oxides and carbonate content, but its aluminum content could inhibit plant growth if soil pH values fall below optimal agronomic levels. This study measured root and shoot growth of an acid-sensitive barley (Hordeum vulgare L. 'Kearney') grown in the greenhouse on three naturally acid soils. The soils were either untreated or amended with various <span class="hlt">liming</span> materials (dry fly ash, wet fly ash, and agricultural <span class="hlt">lime</span>) at application rates of 0, .5, 1, and 1.5 times the recommended <span class="hlt">lime</span> requirement, then treated with dilute acid solutions to simulate management-induced acidification. Plant growth indexes were measured at 30 days after planting. Root mass per plant and root length per plant were greater for the <span class="hlt">limed</span> treatments than in the acidified check. Root growth in the <span class="hlt">limed</span> treatments did not differ from root growth in the original nonacidified soils. Top mass per plant in all <span class="hlt">limed</span> soils was either larger than or not different from that in the original nonacidified soils. Based on top mass per plant, no <span class="hlt">liming</span> material or application rate was clearly superior. Both fly ash and agricultural <span class="hlt">lime</span> reduced the impact of subsequent acidification on young barley plants. Detrimental effects of aluminum release on plant growth were not observed. Calcium-rich fly ash at agronomic rates is an acceptable acid-neutralizing material with no apparent negative effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24146514','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24146514"><span>Cytotoxic and antibacterial activity of the mixture of olive oil and <span class="hlt">lime</span> cream in vitro conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sumer, Zeynep; Yildirim, Gulay; Sumer, Haldun; Yildirim, Sahin</p> <p>2013-01-01</p> <p>The mixture of olive oil and <span class="hlt">lime</span> cream has been traditionally used to treat external burns in the region of Hatay/Antakya and middle Anatolia. Olive oil and <span class="hlt">lime</span> cream have been employed by many physicians to treat many ailments in the past. A limited number of studies have shown the antibacterial effect of olive oil and that it does not have any toxic effect on the skin. But we did not find any reported studies on the mixture of olive oil and <span class="hlt">lime</span> cream. The aim of this paper is to investigate the cytotoxic and antibacterial activity of olive oil and <span class="hlt">lime</span> cream individually or/and in combination in vitro conditions, by using disk-diffusion method and in cell culture. The main purpose in using this mixture is usually to clear burns without a trace. Agar overlay, MTT (Cytotoxicity assay) and antibacterial susceptibility tests were used to investigate the cytotoxic and antibacterial activity of olive oil and <span class="hlt">lime</span> cream. We found that <span class="hlt">lime</span> cream has an antibacterial activity but also cytotoxic on the fibroblasts. On the other hand olive oil has limited or no antibacterial effect and it has little or no cytotoxic on the fibroblasts. When we combined <span class="hlt">lime</span> cream and olive oil, olive oil reduced its cytotoxic impact. These results suggest that mixture of olive oil and <span class="hlt">lime</span> cream is not cytotoxic and has antimicrobial activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15344932','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15344932"><span>Impact of <span class="hlt">lime</span>, nitrogen and plant species on bacterial community structure in grassland microcosms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kennedy, Nabla; Brodie, Eoin; Connolly, John; Clipson, Nicholas</p> <p>2004-10-01</p> <p>A microcosm-based approach was used to study impacts of plant and chemical factors on the bacterial community structure of an upland acidic grassland soil. Seven perennial plant species typical of both natural, unimproved (Nardus stricta, Agrostis capillaris, Festuca ovina and F. rubra) and fertilized, improved (Holcus lanatus, Lolium perenne and Trifolium repens) grasslands were either left unamended or treated with <span class="hlt">lime</span>, nitrogen, or <span class="hlt">lime</span> plus nitrogen in a 75-day glasshouse experiment. <span class="hlt">Lime</span> and nitrogen amendment were shown to have a greater effect on microbial activity, biomass and bacterial ribotype number than plant species. <span class="hlt">Liming</span> increased soil pH, microbial activity and biomass, while decreasing ribotype number. Nitrogen addition decreased soil pH, microbial activity and ribotype number. Addition of <span class="hlt">lime</span> plus nitrogen had intermediate effects, which appeared to be driven more by <span class="hlt">lime</span> than nitrogen. Terminal restriction fragment length polymorphism (TRFLP) analysis revealed that <span class="hlt">lime</span> and nitrogen addition altered soil bacterial community structure, while plant species had little effect. These results were further confirmed by multivariate redundancy analysis, and suggest that soil <span class="hlt">lime</span> and nitrogen status are more important controllers of bacterial community structure than plant rhizosphere effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6863258','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6863258"><span>Controls of carbonate mineralogy and solid-solution of Mg in <span class="hlt">calcite</span>: evidence from spelean systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gonzalez, L.A.; Lohmann, K.C.</p> <p>1985-01-01</p> <p>Precipitation of carbonate minerals in spelean systems occurs under a wide range of fluid chemistry, Mg-Ca ratios, alkalinities, pH and temperatures; thus, spelean systems provide ideal settings to determine factors controlling the mineralogy of precipitated carbonates and solid-solution of Mg in <span class="hlt">calcite</span>. Cave waters and actively-precipitating carbonate speleothems were collected from Carlsbad Caverns National Park, New Mexico and the Mammoth-Flint Cave System, Kentucky. Carbonate mineralogy of precipitated phases was determined by x-ray diffraction, and major and minor element composition of waters and accompanying minerals were determined by Atomic Absorption Spectrophotometry. Results demonstrate that at a constant CO3 concentration the precipitation threshold for <span class="hlt">calcite</span> to aragonite is controlled dominantly by the Mg/Ca ratio of the ambient fluid. Aragonite precipitation is favored by high Mg/Ca ratios. Conversely, with increasing CO3 concentration at constant fluid Mg/Ca ratios, <span class="hlt">calcite</span> is preferentially precipitated. Solid-solution of Mg in <span class="hlt">calcite</span> is positively correlated with both increased Mg/Ca ratios and CO3 concentrations. These data suggest that Mg contents of <span class="hlt">calcite</span> can not be defined solely in terms of a homogeneous distribution coefficient. Rather, Mg concentrations can be also be affected by the CO3 concentration and degree of <span class="hlt">calcite</span> saturation, suggesting that the rate of crystal growth also plays and important role in Mg solid-solution in <span class="hlt">calcites</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26852350','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26852350"><span>Influence of surface conductivity on the apparent zeta potential of <span class="hlt">calcite</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Shuai; Leroy, Philippe; Heberling, Frank; Devau, Nicolas; Jougnot, Damien; Chiaberge, Christophe</p> <p>2016-04-15</p> <p>Zeta potential is a physicochemical parameter of particular importance in describing the surface electrical properties of charged porous media. However, the zeta potential of <span class="hlt">calcite</span> is still poorly known because of the difficulty to interpret streaming potential experiments. The Helmholtz-Smoluchowski (HS) equation is widely used to estimate the apparent zeta potential from these experiments. However, this equation neglects the influence of surface conductivity on streaming potential. We present streaming potential and electrical conductivity measurements on a <span class="hlt">calcite</span> powder in contact with an aqueous NaCl electrolyte. Our streaming potential model corrects the apparent zeta potential of <span class="hlt">calcite</span> by accounting for the influence of surface conductivity and flow regime. We show that the HS equation seriously underestimates the zeta potential of <span class="hlt">calcite</span>, particularly when the electrolyte is diluted (ionic strength ⩽ 0.01 M) because of <span class="hlt">calcite</span> surface conductivity. The basic Stern model successfully predicted the corrected zeta potential by assuming that the zeta potential is located at the outer Helmholtz plane, i.e. without considering a stagnant diffuse layer at the <span class="hlt">calcite</span>-water interface. The surface conductivity of <span class="hlt">calcite</span> crystals was inferred from electrical conductivity measurements and computed using our basic Stern model. Surface conductivity was also successfully predicted by our surface complexation model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4142853','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4142853"><span>Direct nanoscale observations of the coupled dissolution of <span class="hlt">calcite</span> and dolomite and the precipitation of gypsum</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cama, Jordi; Soler, Josep Maria; Putnis, Christine V</p> <p>2014-01-01</p> <p>Summary In-situ atomic force microscopy (AFM) experiments were performed to study the overall process of dissolution of common carbonate minerals (<span class="hlt">calcite</span> and dolomite) and precipitation of gypsum in Na2SO4 and CaSO4 solutions with pH values ranging from 2 to 6 at room temperature (23 ± 1 °C). The dissolution of the carbonate minerals took place at the (104) cleavage surfaces in sulfate-rich solutions undersaturated with respect to gypsum, by the formation of characteristic rhombohedral-shaped etch pits. Rounding of the etch pit corners was observed as solutions approached close-to-equilibrium conditions with respect to <span class="hlt">calcite</span>. The calculated dissolution rates of <span class="hlt">calcite</span> at pH 4.8 and 5.6 agreed with the values reported in the literature. When using solutions previously equilibrated with respect to gypsum, gypsum precipitation coupled with <span class="hlt">calcite</span> dissolution showed short gypsum nucleation induction times. The gypsum precipitate quickly coated the <span class="hlt">calcite</span> surface, forming arrow-like forms parallel to the crystallographic orientations of the <span class="hlt">calcite</span> etch pits. Gypsum precipitation coupled with dolomite dissolution was slower than that of <span class="hlt">calcite</span>, indicating the dissolution rate to be the rate-controlling step. The resulting gypsum coating partially covered the surface during the experimental duration of a few hours. PMID:25161860</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25649514','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25649514"><span>Fabrication of porous <span class="hlt">calcite</span> using chopped nylon fiber and its evaluation using rats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ishikawa, Kunio; Tram, Nguyen Xuan Thanh; Tsuru, Kanji; Toita, Riki</p> <p>2015-02-01</p> <p>Although porous <span class="hlt">calcite</span> has attracted attention as bone substitutes, limited studies have been made so far. In the present study, porous <span class="hlt">calcite</span> block was fabricated by introducing chopped nylon fiber as porogen. Ca(OH)2 powder containing 10 wt% chopped nylon fiber was compacted at 150 MPa, and sintered to burn out the fiber and to carbonate the Ca(OH)2 under stream of 1:2 O2-CO2. Sintering of Ca(OH)2 at 750 °C or lower temperature resulted in incomplete burning out of the fiber whereas sintering at 800 °C or higher temperature resulted in the formation of CaO due to the thermal decomposition of Ca(OH)2. However, sintering at 770 °C resulted in complete burning out of the fiber and complete carbonation of Ca(OH)2 to <span class="hlt">calcite</span> without forming CaO. Macro- and micro-porosities of the porous <span class="hlt">calcite</span> were approximately 23 and 16%, respectively. Diameter of the macropores was approximately 100 μm which is suitable for bone tissue penetration. Porous <span class="hlt">calcite</span> block fabricated by this method exhibited good tissue response when implanted in the bone defect in femur of 12-weeks-old rat. Four weeks after implantation, bone bonded on the surface of <span class="hlt">calcite</span>. Furthermore, bone tissue penetrated interior to the macropore at 8 weeks. These results demonstrated the good potential value of porous <span class="hlt">calcite</span> as artificial bone substitutes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25161860','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25161860"><span>Direct nanoscale observations of the coupled dissolution of <span class="hlt">calcite</span> and dolomite and the precipitation of gypsum.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Offeddu, Francesco Giancarlo; Cama, Jordi; Soler, Josep Maria; Putnis, Christine V</p> <p>2014-01-01</p> <p>In-situ atomic force microscopy (AFM) experiments were performed to study the overall process of dissolution of common carbonate minerals (<span class="hlt">calcite</span> and dolomite) and precipitation of gypsum in Na2SO4 and CaSO4 solutions with pH values ranging from 2 to 6 at room temperature (23 ± 1 °C). The dissolution of the carbonate minerals took place at the (104) cleavage surfaces in sulfate-rich solutions undersaturated with respect to gypsum, by the formation of characteristic rhombohedral-shaped etch pits. Rounding of the etch pit corners was observed as solutions approached close-to-equilibrium conditions with respect to <span class="hlt">calcite</span>. The calculated dissolution rates of <span class="hlt">calcite</span> at pH 4.8 and 5.6 agreed with the values reported in the literature. When using solutions previously equilibrated with respect to gypsum, gypsum precipitation coupled with <span class="hlt">calcite</span> dissolution showed short gypsum nucleation induction times. The gypsum precipitate quickly coated the <span class="hlt">calcite</span> surface, forming arrow-like forms parallel to the crystallographic orientations of the <span class="hlt">calcite</span> etch pits. Gypsum precipitation coupled with dolomite dissolution was slower than that of <span class="hlt">calcite</span>, indicating the dissolution rate to be the rate-controlling step. The resulting gypsum coating partially covered the surface during the experimental duration of a few hours.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002A%26A...395L..29C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002A%26A...395L..29C"><span>Discovery of <span class="hlt">calcite</span> in the solar type protostar NGC 1333-IRAS 4</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ceccarelli, C.; Caux, E.; Tielens, A. G. G. M.; Kemper, F.; Waters, L. B. F. M.; Phillips, T.</p> <p>2002-11-01</p> <p>We present observations, obtained with ISO-LWS, of the continuum between 50-200 mu m of the solar type protostar IRAS 4, in the NGC 1333 complex. The continuum presents an excess, around 95 mu m, that we demonstrate must be a dust feature. We compared the 95 mu m excess with the <span class="hlt">calcite</span> feature at 92 mu m and find that it fits the observations reasonably well. There may be a further contribution from hydrous silicates at ~ 100 mu m, but this seems a less robust result. The detected <span class="hlt">calcite</span> mass is ~ 8 x 10-5 Msun and represents about 1% of the warm ( ~ 23 K) dust mass surrounding IRAS 4. This is only the second observation indicating the presence of carbonates outside the solar system, and the first revealing <span class="hlt">calcite</span> in a young protostar. It is remarkable and intriguing that in all the objects where <span class="hlt">calcite</span> has been detected so far, namely meteorites, planetary nebulae and IRAS 4, it represents from 0.3 to 1% of the dust mass. This new detection of <span class="hlt">calcite</span> strengthens the claim by Kemper et al. (2002a) that <span class="hlt">calcite</span> formation does not necessarely requires liquid water. We suggest that <span class="hlt">calcite</span> forms at the surface of the grains, where water ice layers may locally have an enhanced mobility caused by heating due to hard X-rays emitted by the central object.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8482Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8482Y"><span>Study of Formation Mechanisms of Gas <span class="hlt">Hydrate</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Jia-Sheng; Wu, Cheng-Yueh; Hsieh, Bieng-Zih</p> <p>2015-04-01</p> <p>Gas <span class="hlt">hydrates</span>, which had been found in subsurface geological environments of deep-sea sediments and permafrost regions, are solid crystalline compounds of gas molecules and water. The estimated energy resources of <span class="hlt">hydrates</span> are at least twice of that of the conventional fossil fuel in the world. Gas <span class="hlt">hydrates</span> have a great opportunity to become a dominating future energy. In the past years, many laboratory experiments had been conducted to study chemical and thermodynamic characteristics of gas <span class="hlt">hydrates</span> in order to investigate the formation and dissociation mechanisms of <span class="hlt">hydrates</span>. However, it is difficult to observe the formation and dissociation of <span class="hlt">hydrates</span> in a porous media from a physical experiment directly. The purpose of this study was to model the dynamic formation mechanisms of gas <span class="hlt">hydrate</span> in porous media by reservoir simulation. Two models were designed for this study: 1) a closed-system static model with separated gas and water zones; this model was a <span class="hlt">hydrate</span> equilibrium model to investigate the behavior of the formation of <span class="hlt">hydrates</span> near the initial gas-water contact; and 2) an open-system dynamic model with a continuous bottom-up gas flow; this model simulated the behavior of gas migration and studied the formation of <span class="hlt">hydrates</span> from flowed gas and static formation water in porous media. A phase behavior module was developed in this study for reservoir simulator to model the pressure-volume-temperature (PVT) behavior of <span class="hlt">hydrates</span>. The thermodynamic equilibriums and chemical reactions were coupled with the phase behavior module to have functions modelling the formation and dissociation of <span class="hlt">hydrates</span> from/to water and gas. The simulation models used in this study were validated from the code-comparison project proposed by the NETL. According to the modelling results of the closed-system static model, we found that predominated location for the formation of <span class="hlt">hydrates</span> was below the gas-water contact (or at the top of water zone). The maximum <span class="hlt">hydrate</span> saturation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.188..189C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.188..189C"><span>Uranium isotope fractionation during coprecipitation with aragonite and <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Xinming; Romaniello, Stephen J.; Herrmann, Achim D.; Wasylenki, Laura E.; Anbar, Ariel D.</p> <p>2016-09-01</p> <p>Natural variations in 238U/235U of marine calcium carbonates might provide a useful way of constraining redox conditions of ancient environments. In order to evaluate the reliability of this proxy, we conducted aragonite and <span class="hlt">calcite</span> coprecipitation experiments at pH ∼7.5 and ∼8.5 to study possible U isotope fractionation during incorporation into these minerals. Small but significant U isotope fractionation was observed in aragonite experiments at pH ∼8.5, with heavier U isotopes preferentially enriched in the solid phase. 238U/235U of dissolved U in these experiments can be fit by Rayleigh fractionation curves with fractionation factors of 1.00007 + 0.00002/-0.00003, 1.00005 ± 0.00001, and 1.00003 ± 0.00001. In contrast, no resolvable U isotope fractionation was observed in an aragonite experiment at pH ∼7.5 or in <span class="hlt">calcite</span> experiments at either pH. Equilibrium isotope fractionation among different aqueous U species is the most likely explanation for these findings. Certain charged U species are preferentially incorporated into calcium carbonate relative to the uncharged U species Ca2UO2(CO3)3(aq), which we hypothesize has a lighter equilibrium U isotope composition than most of the charged species. According to this hypothesis, the magnitude of U isotope fractionation should scale with the fraction of dissolved U that is present as Ca2UO2(CO3)3(aq). This expectation is confirmed by equilibrium speciation modeling of our experiments. Theoretical calculation of the U isotope fractionation factors between different U species could further test this hypothesis and our proposed fractionation mechanism. These findings suggest that U isotope variations in ancient carbonates could be controlled by changes in the aqueous speciation of seawater U, particularly changes in seawater pH, PCO2 , Ca2+, or Mg2+ concentrations. In general, these effects are likely to be small (<0.13‰), but are nevertheless potentially significant because of the small natural range of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16887167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16887167"><span>The use of a sequential leaching procedure for assessing the heavy metal leachability in <span class="hlt">lime</span> waste from the <span class="hlt">lime</span> kiln at a caustizicing process of a pulp mill.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pöykiö, Risto; Nurmesniemi, Hannu; Kuokkanen, Toivo; Perämäki, Paavo</p> <p>2006-12-01</p> <p>A five-stage sequential leaching procedure was used to fractionate 13 heavy metals (Cd, Cu, Pb, Cr, Zn, Fe, Mn, Al, Ni, Co, As, V, Ba) and sulphur (S) in <span class="hlt">lime</span> waste from the <span class="hlt">lime</span> kiln at the causticizing plant of Stora Enso Oyj Veitsiluoto Pulp Mills at Kemi, Northern Finland, into the following fractions: (1) water-soluble fraction (H(2)O), (2) exchangeable fraction (CH(3)COOH), (3) easily reduced fraction (HONH(3)Cl), (4) oxidizable fraction (H(2)O(2)+CH(3)COONH(4)), and (5) residual fraction (HF+HNO(3)+HCl). Although metals were leachable in all fractions, the highest concentrations for most of the metals were observed in the residual fraction (stage 5). It was also notable that the total heavy metal concentrations in <span class="hlt">lime</span> waste did not exceed the maximal allowable heavy metal concentrations for soil conditioner agents set by the ministry of the Agricultural and Forestry in Finland. The heavy metals concentrations in <span class="hlt">lime</span> waste were also lower than the maximal allowable heavy metals concentrations of the European Union Directive 86/278/EEC on the protection of environment, and in particular of the soil, when sewage sludge is used in agriculture. The Ca concentration (420 g kg(-1); d.w.) was about 262 times higher than the typical value of 1.6 g kg(-1) (d.w.) in arable land in Central Finland. However, the concentration Mg (0.2 g kg(-1); d.w.) in <span class="hlt">lime</span> waste was equal to the Mg concentration in arable land in the Central Finland. The <span class="hlt">lime</span> waste has strongly alkaline pH ( approximately 12.8) and a neutralizing value (i.e. <span class="hlt">liming</span> effect) of 47.9% expressed as Ca equivalents (d.w.). This indicates <span class="hlt">lime</span> waste to be a potential soil conditioner and improvement as well as a pH buffer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21768106','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21768106"><span><span class="hlt">Calcite</span> formation in soft coral sclerites is determined by a single reactive extracellular protein.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rahman, M Azizur; Oomori, Tamotsu; Wörheide, Gert</p> <p>2011-09-09</p> <p>Calcium carbonate exists in two main forms, <span class="hlt">calcite</span> and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called "<span class="hlt">calcite</span> and aragonite seas." Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce <span class="hlt">calcite</span> despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form <span class="hlt">calcitic</span> skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces <span class="hlt">calcite</span> formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of <span class="hlt">calcite</span> instead of aragonite in the biocalcification process and that -OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the <span class="hlt">calcite</span> crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different <span class="hlt">calcite</span>-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of <span class="hlt">calcite</span> in nature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3173117','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3173117"><span><span class="hlt">Calcite</span> Formation in Soft Coral Sclerites Is Determined by a Single Reactive Extracellular Protein*</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rahman, M. Azizur; Oomori, Tamotsu; Wörheide, Gert</p> <p>2011-01-01</p> <p>Calcium carbonate exists in two main forms, <span class="hlt">calcite</span> and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called “<span class="hlt">calcite</span> and aragonite seas.” Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce <span class="hlt">calcite</span> despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form <span class="hlt">calcitic</span> skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces <span class="hlt">calcite</span> formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of <span class="hlt">calcite</span> instead of aragonite in the biocalcification process and that –OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the <span class="hlt">calcite</span> crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different <span class="hlt">calcite</span>-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of <span class="hlt">calcite</span> in nature. PMID:21768106</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005APS..SHK.D5001G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005APS..SHK.D5001G"><span>Time dependent inelastic deformation of shocked soda-<span class="hlt">lime</span> glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gupta, Y. M.</p> <p>2005-07-01</p> <p>Shock wave compression of soda-<span class="hlt">lime</span> glass (SLG) has received considerable attention in recent years. To understand inelastic deformation in shocked soda-<span class="hlt">lime</span> glass between 3 and 10.8 GPa, we have carried out plate impact experiments. In-material, time-resolved, measurements were obtained using longitudinal and lateral stress gauges (4.6 to 10.8 GPa), and electromagnetic particle velocity gauges (2.9 to 6 GPa) at comparable sample thicknesses. The 4.6 and 6 GPa experiments revealed time-dependent inelastic response along with time-dependent loss of material strength. The combination of our experimental results and related analyses demonstrate that previous interpretations of shocked SLG response in terms of a propagating failure wave are not valid. At higher peak stresses (˜ 10GPa), the SLG results do not display time-dependent strength loss. The shock response of SLG over the 4-10GPa range is complex and depends significantly on the peak stress. The experimental results and simulations from a phenomenological continuum model will be discussed. Work supported by DOE. Much of this work was carried out by Dr. Hari Simha.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6328679','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6328679"><span>Late Mississippian <span class="hlt">lime</span> mud mounds, Pitkin Formation, northern Arkansas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Manger, W.L.; Ar, V.P.; Webb, G.E.</p> <p>1984-04-01</p> <p>Carbonates deposited under shallow, open shelf conditions during the Late Mississippian in northern Arkansas exhibit numerous discrete to coalescing <span class="hlt">lime</span> mud mounds up to 20 m (65 ft) high and tens of meters in diameter. The mounds are composed of a carbonate mud core, typically with fenestrate texture, entrapped by a loosely organized framework dominated by cystoporate bryozoans and rugose corals in the lower part, and by blue-green algae and cryptostomous bryozoans in the upper part. Disarticulated crinozoan detritus is common throughout the core, suggesting that these organisms also contributed to entrapment of <span class="hlt">lime</span> mud. During deposition, the mud core was indurated enough to support and preserve vertical burrows. Also, rubble of core mudstone is found on the flanks of some mounds, suggesting some erosion. Intermound lithology is a shoaling-upward sequence dominated by oolitic and bioclastic grainstones and packstones. Shale is also present in minor amounts. The Pitkin mounds, interbedded with these intermound sequences, developed contemporaneously with them. Depositional relief was probably less than 3 m (10 ft). The mounds expanded laterally during periods of quieter water; their growth was impeded during times of higher energy. Contacts of the mound and intermound lithologic characteristics are sharp, truncating surfaces. Mound deposition ended with the onset of high energy conditions throughout the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6740196','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6740196"><span>Computerized Shawnee <span class="hlt">lime</span>/limestone scrubbing model users manual</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Anders, W.L.; Torstrick, R.L.</p> <p>1981-03-01</p> <p>The manual gives a general description of a computerized model for estimating design and cost of <span class="hlt">lime</span> or limestone scrubber systems for flue gas desulfurization (FGD). It supplements PB80-123037 by extending the number of scrubber options which can be evaluated. It includes spray tower and venturi/spray-tower absorbers, forced oxidation systems, systems with absorber loop additives (MgO or adipic acid), revised design and economic premises, and other changes reflecting process improvements and variations. It describes all inputs and outputs, along with detailed procedures for using the model and all its options. The model is based on prototype scrubber data from the EPA/Shawnee test facility and should be useful to utility companies, as well as to architectural and engineering contractors who are involved in selecting and designing FGD facilities. As key features, the model provides estimates of capital investment and operating revenue requirements. It also provides a material balance, equipment list, and a breakdown of costs by processing areas. The primary uses of the model are to project comparative economics of <span class="hlt">lime</span> and limestone FGD processes and to evaluate system alternatives prior to the development of a detailed design.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5673525','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5673525"><span>Development of Alaskan gas <span class="hlt">hydrate</span> resources</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kamath, V.A.; Sharma, G.D.; Patil, S.L.</p> <p>1991-06-01</p> <p>The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas <span class="hlt">hydrates</span> such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of <span class="hlt">hydrate</span> cores. An experimental study has been conducted to measure the effective gas permeability changes as <span class="hlt">hydrates</span> form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of <span class="hlt">hydrate</span> saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas <span class="hlt">hydrates</span> in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of <span class="hlt">hydrates</span> during hot water injection process.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21435773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21435773"><span>Structural characteristics of <span class="hlt">hydration</span> sites in lysozyme.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Soda, Kunitsugu; Shimbo, Yudai; Seki, Yasutaka; Taiji, Makoto</p> <p>2011-06-01</p> <p>A new method is presented for determining the <span class="hlt">hydration</span> site of proteins, where the effect of structural fluctuations in both protein and <span class="hlt">hydration</span> water is explicitly considered by using molecular dynamics simulation (MDS). The whole <span class="hlt">hydration</span> sites (HS) of lysozyme are composed of 195 single HSs and 38 clustered ones (CHS), and divided into 231 external HSs (EHS) and 2 internal ones (IHS). The largest CHSs, 'Hg' and 'Lβ', are the IHSs having 2.54 and 1.35 mean internal <span class="hlt">hydration</span> waters respectively. The largest EHS, 'Clft', is located in the cleft region. The real <span class="hlt">hydration</span> structure of a CHS is an ensemble of multiple structures. The transition between two structures occurs through recombinations of some H-bonds. The number of the experimental X-ray crystal waters is nearly the same as that of the estimated MDS <span class="hlt">hydration</span> waters for 70% of the HSs, but significantly different for the rest of HSs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22432618','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22432618"><span>Fundamentals and applications of gas <span class="hlt">hydrates</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Koh, Carolyn A; Sloan, E Dendy; Sum, Amadeu K; Wu, David T</p> <p>2011-01-01</p> <p>Fundamental understanding of gas <span class="hlt">hydrate</span> formation and decomposition processes is critical in many energy and environmental areas and has special importance in flow assurance for the oil and gas industry. These areas represent the core of gas <span class="hlt">hydrate</span> applications, which, albeit widely studied, are still developing as growing fields of research. Discovering the molecular pathways and chemical and physical concepts underlying gas <span class="hlt">hydrate</span> formation potentially can lead us beyond flowline blockage prevention strategies toward advancing new technological solutions for fuel storage and transportation, safely producing a new energy resource from natural deposits of gas <span class="hlt">hydrates</span> in oceanic and arctic sediments, and potentially facilitating effective desalination of seawater. The state of the art in gas <span class="hlt">hydrate</span> research is leading us to new understanding of formation and dissociation phenomena that focuses on measurement and modeling of time-dependent properties of gas <span class="hlt">hydrates</span> on the basis of their well-established thermodynamic properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5381282','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5381282"><span>Characterization of <span class="hlt">limes</span> (Citrus aurantifolia) grown in Bhutan and Indonesia using high-throughput sequencing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Penjor, Tshering; Mimura, Takashi; Matsumoto, Ryoji; Yamamoto, Masashi; Nagano, Yukio</p> <p>2014-01-01</p> <p><span class="hlt">Lime</span> [Citrus aurantifolia (Cristm.) Swingle] is a Citrus species that is a popular ingredient in many cuisines. Some citrus plants are known to originate in the area ranging from northeastern India to southwestern China. In the current study, we characterized and compared <span class="hlt">limes</span> grown in Bhutan (n = 5 accessions) and Indonesia (n = 3 accessions). The <span class="hlt">limes</span> were separated into two groups based on their morphology. Restriction site-associated DNA sequencing (RAD-seq) separated the eight accessions into two clusters. One cluster contained four accessions from Bhutan, whereas the other cluster contained one accession from Bhutan and the three accessions from Indonesia. This genetic classification supported the morphological classification of <span class="hlt">limes</span>. The analysis suggests that the properties associated with asexual reproduction, and somatic homologous recombination, have contributed to the genetic diversification of <span class="hlt">limes</span>. PMID:24781859</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012IJMMM..19..973P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012IJMMM..19..973P"><span>Pre-desilication and digestion of gibbsitic bauxite with <span class="hlt">lime</span> in sodium aluminate liquor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pan, Xiao-lin; Yu, Hai-yan; Dong, Kai-wei; Tu, Gan-feng; Bi, Shi-wen</p> <p>2012-11-01</p> <p>The effect of <span class="hlt">lime</span> on the pre-desilication and digestion of gibbsitic bauxite in synthetic sodium aluminate liquor at different temperatures was investigated. The bauxite is comprised of gibbsite, aluminogoethite, hematite, kaolin, quartz, and minor boehmite. <span class="hlt">Lime</span> increases the desilication efficiency of the bauxite during the pre-desilication process by promoting the conversion of sodalite and cancrinite to hydrogarnet. Desilication reactions during the digestion process promoted by <span class="hlt">lime</span> result in the loss of Al2O3 entering the red mud, but the amount of aluminogoethite-to-hematite conversion promoted by <span class="hlt">lime</span> leads to the increase of aluminogoethitic Al2O3 entering the digested liquor. The alumina digestion rate at 245°C is higher than that at 145°C due to the more pronounced conversion of aluminogoethite to hematite. The soda consumption during the digestion process decreases due to <span class="hlt">lime</span> addition, especially at higher temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016049','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016049"><span>Activators of photoluminescence in <span class="hlt">calcite</span>: evidence from high-resolution, laser-excited luminescence spectroscopy</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pedone, V.A.; Cercone, K.R.; Burruss, R.C.</p> <p>1990-01-01</p> <p>Laser-excited luminescence spectroscopy of a red-algal, biogenic <span class="hlt">calcite</span> and a synthetic Mn-<span class="hlt">calcite</span> can make the distinction between organic and trace-element activators of photoluminescence. Organic-activated photoluminescence in biogenic <span class="hlt">calcite</span> is characterized by significant peak shifts and increasing intensity with shorter-wavelength excitation and by significant decreases in intensity after heating to ??? 400??C. In contrast, Mn-activated photoluminescence shows no peak shift, greatest intensity under green excitation and limited changes after heating. Examination of samples with a high-sensitivity spectrometer using several wavelengths of exciting light is necessary for identification of photoluminescence activators. ?? 1990.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4996599','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4996599"><span>Recurrent Pure <span class="hlt">Calcite</span> Urolithiasis Confirmed by Endoscopic Removal and Infrared Spectroscopy in a Malnourished Anorectic Female</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Andreassen, Kim Hovgaard; Sloth Osther, Palle Jörn</p> <p>2016-01-01</p> <p>Abstract Often when <span class="hlt">calcite</span> is found as a component of urinary calculi, they are considered false calculi or artifacts. We present a case of true <span class="hlt">calcite</span> urolithiasis. The stone material was removed percutaneously from a severely malnourished anorectic woman and analyzed by infrared spectroscopy (IRS). In addition, <span class="hlt">calcite</span> urolithiasis was confirmed in several recurrent stone events by IRS. Laxative abuse with magnesium oxide was believed to be the underlying cause of stone formation, and ammonium chloride given as one weekly dose turned out to be effective for stone prevention. PMID:27579419</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6795943','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6795943"><span>Potential geologic hazards of Arctic gas <span class="hlt">hydrates</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Collett, T.S. )</p> <p>1990-05-01</p> <p>Sediments of the Arctic region may contain enormous quantities of natural gas in the form of gas <span class="hlt">hydrates</span>, which are crystalline substances composed of water and mostly methane gas. These ice-like substances are generally found in two distinct environments: (1) offshore in sediments of outer continental margins and (2) nearshore and onshore in areas associated with the occurrence of permafrost. Recently, US, Canadian, and Soviet researchers have described numerous drilling and production problems attributed to the presence of gas <span class="hlt">hydrates</span>, including uncontrolled gas releases during drilling, collapsed casings, and gas leakage to the surface. When the drill bit penetrates a gas <span class="hlt">hydrate</span>, the drilling mud, unless cooled significantly by the operator, will become highly gasified as the <span class="hlt">hydrate</span> decomposes. The <span class="hlt">hydrate</span> adjacent to the well bore will continue to decompose and gasify the drilling mud as long as drilling and/or production introduces heat into the <span class="hlt">hydrate</span>-bearing interval. The production of hot fluids from depth through the permafrost and gas <span class="hlt">hydrate</span>-bearing intervals adversely raises formation temperatures, thus decomposing the gas <span class="hlt">hydrates</span>. If the disassociated, free gas is trapped behind the casing, reservoir pressures may substantially increase and cause the casing to collapse. In several wells in northern Alaska, the disassociated free gas has leaked to the surface outside the conductor casing. An additional drilling hazard associated with gas <span class="hlt">hydrates</span> results from the sealing attributes of <span class="hlt">hydrates</span>, which may trap large volumes of over pressured free gas at shallow depths. Even though documented problems attributed to the presence of gas <span class="hlt">hydrates</span> have been relatively few, it is likely that as exploration and development activity moves farther offshore into deeper water (>300 m) and to higher latitudes in the Arctic, the frequency of gas <span class="hlt">hydrate</span>-related problems will increase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6685339','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6685339"><span>Gas <span class="hlt">hydrates</span> of outer continental margins</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kvenvolden, K.A. )</p> <p>1990-05-01</p> <p>Gas <span class="hlt">hydrates</span> are crystalline substances in which a rigid framework of water molecules traps molecules of gas, mainly methane. Gas-<span class="hlt">hydrate</span> deposits are common in continental margin sediment in all major oceans at water depths greater than about 300 m. Thirty-three localities with evidence for gas-<span class="hlt">hydrate</span> occurrence have been described worldwide. The presence of these gas <span class="hlt">hydrates</span> has been inferred mainly from anomalous lacoustic reflectors seen on marine seismic records. Naturally occurring marine gas <span class="hlt">hydrates</span> have been sampled and analyzed at about tensites in several regions including continental slope and rise sediment of the eastern Pacific Ocean and the Gulf of Mexico. Except for some Gulf of Mexico gas <span class="hlt">hydrate</span> occurrences, the analyzed gas <span class="hlt">hydrates</span> are composed almost exclusively of microbial methane. Evidence for the microbial origin of methane in gas <span class="hlt">hydrates</span> includes (1) the inverse relation between methane occurence and sulfate concentration in the sediment, (2) the subparallel depth trends in carbon isotopic compositions of methane and bicarbonate in the interstitial water, and (3) the general range of {sup 13}C depletion ({delta}{sub PDB}{sup 13}C = {minus}90 to {minus}60 {per thousand}) in the methane. Analyses of gas <span class="hlt">hydrates</span> from the Peruvian outer continental margin in particular illustrate this evidence for microbially generated methane. The total amount of methane in gas <span class="hlt">hydrates</span> of continental margins is not known, but estimates of about 10{sup 16} m{sup 3} seem reasonable. Although this amount of methane is large, it is not yet clear whether methane <span class="hlt">hydrates</span> of outer continental margins will ever be a significant energy resource; however, these gas <span class="hlt">hydrates</span> will probably constitute a drilling hazard when outer continental margins are explored in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017031','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017031"><span>Natural gas <span class="hlt">hydrate</span> occurrence and issues</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kvenvolden, K.A.</p> <p>1994-01-01</p> <p>Naturally occurring gas <span class="hlt">hydrate</span> is found in sediment of two regions: (1) continental, including continental shelves, at high latitudes where surface temperatures are very cold, and (2) submarine outer continental margins where pressures are very high and bottom-water temperatures are near 0??C. Continental gas <span class="hlt">hydrate</span> is found in association with onshore and offshore permafrost. Submarine gas <span class="hlt">hydrate</span> is found in sediment of continental slopes and rises. The amount of methane present in gas <span class="hlt">hydrate</span> is thought to be very large, but the estimates that have been made are more speculative than real. Nevertheless, at the present time there has been a convergence of ideas regarding the amount of methane in gas <span class="hlt">hydrate</span> deposits worldwide at about 2 x 1016 m3 or 7 x 1017 ft3 = 7 x 105 Tcf [Tcf = trillion (1012) ft3]. The potentially large amount of methane in gas <span class="hlt">hydrate</span> and the shallow depth of gas <span class="hlt">hydrate</span> deposits are two of the principal factors driving research concerning this substance. Such a large amount of methane, if it could be commercially produced, provides a potential energy resource for the future. Because gas <span class="hlt">hydrate</span> is metastable, changes of surface pressure and temperature affect its stability. Destabilized gas <span class="hlt">hydrate</span> beneath the sea floor leads to geologic hazards such as submarine mass movements. Examples of submarine slope failures attributed to gas <span class="hlt">hydrate</span> are found worldwide. The metastability of gas <span class="hlt">hydrate</span> may also have an effect on climate. The release of methane, a 'greenhouse' gas, from destabilized gas <span class="hlt">hydrate</span> may contribute to global warming and be a factor in global climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2010-06-10/pdf/2010-13934.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2010-06-10/pdf/2010-13934.pdf"><span>75 FR 32900 - Notice of Availability of a Pest Risk Analysis for the Importation of Sweet <span class="hlt">Limes</span> From Mexico...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2010-06-10</p> <p>... Analysis for the Importation of Sweet <span class="hlt">Limes</span> From Mexico Into the Continental United States AGENCY: Animal... have prepared a pest risk analysis that evaluates the risks associated with the importation of sweet... sweet <span class="hlt">limes</span> (Citrus limetta) into the continental United States. Currently, sweet <span class="hlt">limes</span> are...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1236222-alkaline-flocculation-phaeodactylum-tricornutum-induced-brucite-calcite','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1236222-alkaline-flocculation-phaeodactylum-tricornutum-induced-brucite-calcite"><span>Alkaline flocculation of Phaeodactylum tricornutum induced by brucite and <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Vandamme, Dries; Pohl, Philip I.; Beuckels, Annelies; ...</p> <p>2015-08-20</p> <p>Alkaline flocculation holds great potential as a low-cost harvesting method for marine microalgae biomass production. Alkaline flocculation is induced by an increase in pH and is related to precipitation of calcium and magnesium salts. In this study, we used the diatom Phaeodactylum tricornutum as model organism to study alkaline flocculation of marine microalgae cultured in seawater medium. Flocculation started when pH was increased to 10 and flocculation efficiency reached 90% when pH was 10.5, which was consistent with precipitation modeling for brucite or Mg(OH)2. Compared to freshwater species, more magnesium is needed to achieve flocculation (>7.5 mM). Zeta potential measurementsmore » suggest that brucite precipitation caused flocculation by charge neutralization. When calcium concentration was 12.5 mM, flocculation was also observed at a pH of 10. Furthermore, zeta potential remained negative up to pH 11.5, suggesting that precipitated <span class="hlt">calcite</span> caused flocculation by a sweeping coagulation mechanism.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984JCrGr..66..639M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984JCrGr..66..639M"><span>The influence of impurities on the growth rate of <span class="hlt">calcite</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, H. J.</p> <p>1984-05-01</p> <p>The effects of 34 different additives on the growth rate of <span class="hlt">calcite</span> were investigated. An initial growth rate of about one crystal monolayer (3 × 10 -8 cm) per minute was adjusted at a constant supersaturation which was maintained by a control circuit. Then the impurity was added step by step and the reduction of the growth rate was measured. The impurity concentration necessary to reduce the initial growth rate by a certain percentage increased in the order Fe 2+, ATP, P 3O 5-10, P 2O 4-7, (PO 3) 6-6, Zn 2+, ADP, Ce 3+, Pb 2+, carbamyl phosphate, Fe 3+, PO 3-4, Co 2+, Mn 2+, Be 2+, β-glycerophosphate, Ni 2+, Cd 2+, "Tris", phenylphosphate, chondroitine sulphate, Ba 2+, citrate, AMP, Sr 2+, tricarballylate, taurine, SO 2-4, Mg 2+ by 4 orders of magnitude. The most effective additives halved the initial growth rate in concentrations of 2 × 10 -8 mol/1. For Fe 2+ the halving concentration was nearly proportional to the initial rate. The mechanism of inhibition by adsorption of the impurities at growth sites (kinks) is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4991261','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4991261"><span>Thin-film-induced morphological instabilities over <span class="hlt">calcite</span> surfaces</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vesipa, R.; Camporeale, C.; Ridolfi, L.</p> <p>2015-01-01</p> <p>Precipitation of calcium carbonate from water films generates fascinating <span class="hlt">calcite</span> morphologies that have attracted scientific interest over past centuries. Nowadays, speleothems are no longer known only for their beauty but they are also recognized to be precious records of past climatic conditions, and research aims to unveil and understand the mechanisms responsible for their morphological evolution. In this paper, we focus on crenulations, a widely observed ripple-like instability of the the calcite–water interface that develops orthogonally to the film flow. We expand a previous work providing new insights about the chemical and physical mechanisms that drive the formation of crenulations. In particular, we demonstrate the marginal role played by carbon dioxide transport in generating crenulation patterns, which are indeed induced by the hydrodynamic response of the free surface of the water film. Furthermore, we investigate the role of different environmental parameters, such as temperature, concentration of dissolved ions and wall slope. We also assess the convective/absolute nature of the crenulation instability. Finally, the possibility of using crenulation wavelength as a proxy of past flows is briefly discussed from a theoretical point of view. PMID:27547086</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001GeoJI.144...96R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001GeoJI.144...96R"><span>Stress remagnetization in pyrrhotite-<span class="hlt">calcite</span> synthetic aggregates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robion, Philippe; Borradaile, Graham J.</p> <p>2001-01-01</p> <p>Stress-induced remagnetization has been applied to multidomain pyrrhotite-<span class="hlt">calcite</span> synthetic aggregates in a triaxial rig. Experimental deformation used 150MPa confining pressure, a constant strain rate of 10-5 s-1 and applied differential stresses of up to 70MPa. New components of magnetization, parallel to the direction of the pressure vessel field, were added to the pre-deformational magnetization. The intensity of remagnetization (M'-M0) increases with the intensity of the applied differential stress and affects the coercivity fraction below 15mT. Bulk shortening is less than 8 per cent, thus grain rotation cannot explain selective remagnetization of the low-coercivity fraction. Remagnetization is thus attributed to deformational viscous remanent magnetization (DVRM). It is observed that high-coercivity (>15mT) grains do not remagnetize. There is, however, slight progressive rotation of pre-deformational magnetization with increasing strain up to 8 per cent of bulk shortening. The lack of piezoremanent magnetization in the high-coercivity range may be due to defects introduced in pyrrhotite during sample preparation. Experiments using synthetic pyrrhotite, expected to show low dislocation densities, would be necessary to test this effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19630003648&hterms=calcite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcalcite','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19630003648&hterms=calcite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcalcite"><span>Ultrasonic Observation of the <span class="hlt">Calcite</span>-Aragonite Transition</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ahrens, T. J.; Katz, S.</p> <p>1963-01-01</p> <p>Elastic-wave velocities were measured as a function of pressure by ultrasonic pulse Interferometry in Solenhofen and Manilus limestone specimens to pressures of 27 and 38 kb. Longitudinal velocities decrease sharply from 5.3 km/sec at a mean pressure of 4 kb to a minimum of 4.8 km/sec at 8 kb. Transverse velocities decrease from 3.1 to 2.9 km/sec. At the minimum bulk and rigidity moduli are 25 and 20 per cent below their 4-kb values. A density increase of 1.7 per cent is associated with this minimum. The observed effects are attributed to the <span class="hlt">calcite</span>-aragonite transition, and they may be due to an inherent property of the material, a component of which undergoes a polymorphic transition, the low- and high-pressure phases coexisting over a considerable pressure range. This may be an additional mechanism to account for low-velocity zones in the earth?s interior.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1198273-physical-properties-gas-hydrates-review','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1198273-physical-properties-gas-hydrates-review"><span>Physical Properties of Gas <span class="hlt">Hydrates</span>: A Review</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Gabitto, Jorge F.; Tsouris, Costas</p> <p>2010-01-01</p> <p>Memore » thane gas <span class="hlt">hydrates</span> in sediments have been studied by several investigators as a possible future energy resource. Recent <span class="hlt">hydrate</span> reserves have been estimated at approximately 10 16   m 3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas <span class="hlt">hydrate</span> is necessary in order to commercially exploit the resource from the natural-gas-<span class="hlt">hydrate</span>-bearing sediment. The presence of gas <span class="hlt">hydrates</span> in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of <span class="hlt">hydrate</span>-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas <span class="hlt">hydrates</span>. A brief review of the physical properties of bulk gas <span class="hlt">hydrates</span> is included. Detection methods, morphology, and relevant physical properties of gas-<span class="hlt">hydrate</span>-bearing sediments are also discussed.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/982117','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/982117"><span>Physical Properties of Gas <span class="hlt">Hydrates</span>: A Review</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gabitto, Jorge; Tsouris, Costas</p> <p>2010-01-01</p> <p>Methane gas <span class="hlt">hydrates</span> in sediments have been studied by several investigators as a possible future energy resource. Recent <span class="hlt">hydrate</span> reserves have been estimated at approximately 1016?m3 of methane gas worldwide at standard temperature and pressure conditions. In situ dissociation of natural gas <span class="hlt">hydrate</span> is necessary in order to commercially exploit the resource from the natural-gas-<span class="hlt">hydrate</span>-bearing sediment. The presence of gas <span class="hlt">hydrates</span> in sediments dramatically alters some of the normal physical properties of the sediment. These changes can be detected by field measurements and by down-hole logs. An understanding of the physical properties of <span class="hlt">hydrate</span>-bearing sediments is necessary for interpretation of geophysical data collected in field settings, borehole, and slope stability analyses; reservoir simulation; and production models. This work reviews information available in literature related to the physical properties of sediments containing gas <span class="hlt">hydrates</span>. A brief review of the physical properties of bulk gas <span class="hlt">hydrates</span> is included. Detection methods, morphology, and relevant physical properties of gas-<span class="hlt">hydrate</span>-bearing sediments are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/934586','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/934586"><span>Desalination utilizing clathrate <span class="hlt">hydrates</span> (LDRD final report).</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Simmons, Blake Alexander; Bradshaw, Robert W.; Dedrick, Daniel E.; Cygan, Randall Timothy; Greathouse, Jeffery A.; Majzoub, Eric H.</p> <p>2008-01-01</p> <p>Advances are reported in several aspects of clathrate <span class="hlt">hydrate</span> desalination fundamentals necessary to develop an economical means to produce municipal quantities of potable water from seawater or brackish feedstock. These aspects include the following, (1) advances in defining the most promising systems design based on new types of <span class="hlt">hydrate</span> guest molecules, (2) selection of optimal multi-phase reactors and separation arrangements, and, (3) applicability of an inert heat exchange fluid to moderate <span class="hlt">hydrate</span> growth, control the morphology of the solid <span class="hlt">hydrate</span> material formed, and facilitate separation of <span class="hlt">hydrate</span> solids from concentrated brine. The rate of R141b <span class="hlt">hydrate</span> formation was determined and found to depend only on the degree of supercooling. The rate of R141b <span class="hlt">hydrate</span> formation in the presence of a heat exchange fluid depended on the degree of supercooling according to the same rate equation as pure R141b with secondary dependence on salinity. Experiments demonstrated that a perfluorocarbon heat exchange fluid assisted separation of R141b <span class="hlt">hydrates</span> from brine. Preliminary experiments using the guest species, difluoromethane, showed that <span class="hlt">hydrate</span> formation rates were substantial at temperatures up to at least 12 C and demonstrated partial separation of water from brine. We present a detailed molecular picture of the structure and dynamics of R141b guest molecules within water cages, obtained from ab initio calculations, molecular dynamics simulations, and Raman spectroscopy. Density functional theory calculations were used to provide an energetic and molecular orbital description of R141b stability in both large and small cages in a structure II <span class="hlt">hydrate</span>. Additionally, the <span class="hlt">hydrate</span> of an isomer, 1,2-dichloro-1-fluoroethane, does not form at ambient conditions because of extensive overlap of electron density between guest and host. Classical molecular dynamics simulations and laboratory trials support the results for the isomer <span class="hlt">hydrate</span>. Molecular dynamics simulations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/430279','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/430279"><span>Roller compacted base course construction using <span class="hlt">lime</span> stabilized fly ash and flue gas desulfurization sludge-by-product</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Beeghly, J.H.</p> <p>1996-12-31</p> <p>Dewatered calcium sulfite and calcium sulfate sludges from unoxidized flue gas desulfurization (FGD) processes at coal fired power plants can be mixed with coal fly ash and <span class="hlt">lime</span> to cause a cementitious chemical reaction used to construct a roller compacted base course (RCFGD) or an impermeable pond liner. The chemical reaction is described as time reacting with alumina from the fly ash which in turn reacts with the calcium sulfite and sulfate FGD waste to form calcium sulfo-aluminate compounds. Leachate data is similar to primary drinking water quality standards. Two field demonstrations of RCFGD and a proposed mix design procedure are described. Factors that affect strength gain and freeze-thaw durability such as optimum moisture content, fly ash to FGD ratio, and age of FGD are discussed. Better understanding is needed on how to predict long term strength performance and expansive potential given the nature of long term <span class="hlt">hydration</span> forming ettringite compounds and the vulnerability to destructive freeze-thaw cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710009P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710009P"><span>Control of carbonate alkalinity on Mg incorporation in <span class="hlt">calcite</span>: Insights on the occurrence of high Mg <span class="hlt">calcites</span> in diagenetic environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purgstaller, Bettina; Mavromatis, Vasileios; Dietzel, Martin</p> <p>2015-04-01</p> <p>High Mg <span class="hlt">calcites</span> (HMC), with up to 25 mol % of Mg, are common features in early diagenetic environments and are frequently associated with bio-induced anaerobic oxidation of methane (AOM). Such archives hold valuable information about the biogeochemical processes occurring in sedimentary environments in the geological past. Despite the frequency AOM-induced HMC observed in marine diagenetic settings and their potential role in dolomitization, only a minor number of experimental studies has been devoted on deciphering their formation conditions. Thus, in order to improve our understanding on the formation mechanism of HMC induced by elevated carbonate ion concentrations, we precipitated HMC by computer controlled titration of a (Mg,Ca)Cl2 solution at different Mg/Ca ratios into a NaHCO3 solution under precisely defined physicochemical conditions (T = 25.00 ±0.03°C; pH = 8.3 ±0.1). The formation of carbonates was monitored at a high temporal resolution using in situ Raman spectroscopy as well as by continuous sampling and analyzing of precipitates and reactive solutions. We identified two distinct mechanisms of HMC formation. In solutions with molar Mg/Ca ratios ≤ 1/8 calcium carbonate was precipitated as crystalline phases directly from homogeneous solution. In contrast, higher Mg/Ca ratios induced the formation of Mg-rich ACC (up to 10 mol % of Mg), which was subsequently transformed to HMC with up 20 mol % of Mg. Our experimental results highlight that the finally formed HMC has a higher Mg content than the ACC precursor phase. Considering experimental data for Mg containing ACC transformation to crystalline calcium carbonate from literature, the continuous enrichment of Mg in the precipitate throughout transformation of amorphous to crystalline CaCO3 most likely occurs due to the high carbonate alkalinity (DIC about 0.1 M) of our reactive solutions. The Mg incorporation into <span class="hlt">calcite</span> lattice seems to be favored by intensive supply of carbonate ions as</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70120690','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70120690"><span>Observations related to tetrahydrofuran and methane <span class="hlt">hydrates</span> for laboratory studies of <span class="hlt">hydrate</span>-bearing sediments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, J.Y.; Yun, T.S.; Santamarina, J.C.; Ruppel, C.</p> <p>2007-01-01</p> <p>The interaction among water molecules, guest gas molecules, salts, and mineral particles determines the nucleation and growth behavior of gas <span class="hlt">hydrates</span> in natural sediments. <span class="hlt">Hydrate</span> of tetrahydrofuran (THF) has long been used for laboratory studies of gas <span class="hlt">hydrate</span>-bearing sediments to provide close control on <span class="hlt">hydrate</span> concentrations and to overcome the long formation history of methane <span class="hlt">hydrate</span> from aqueous phase methane in sediments. Yet differences in the polarizability of THF (polar molecule) compared to methane (nonpolar molecule) raise questions about the suitability of THF as a proxy for methane in the study of <span class="hlt">hydrate</span>-bearing sediments. From existing data and simple macroscale experiments, we show that despite its polar nature, THF's large molecular size results in low permittivity, prevents it from dissolving precipitated salts, and hinders the solvation of ions on dry mineral surfaces. In addition, the interfacial tension between water and THF <span class="hlt">hydrate</span> is similar to that between water and methane <span class="hlt">hydrate</span>. The processes that researchers choose for forming <span class="hlt">hydrate</span> in sediments in laboratory settings (e.g., from gas, liquid, or ice) and the pore-scale distribution of the <span class="hlt">hydrate</span> that is produced by each of these processes likely have a more pronounced effect on the measured macroscale properties of <span class="hlt">hydrate</span>-bearing sediments than do differences between THF and methane <span class="hlt">hydrates</span> themselves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24295438','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24295438"><span>Catastrophic growth of gas <span class="hlt">hydrates</span> in the presence of kinetic <span class="hlt">hydrate</span> inhibitors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cha, Minjun; Shin, Kyuchul; Seo, Yutaek; Shin, Ju-Young; Kang, Seong-Pil</p> <p>2013-12-27</p> <p>The effect of the concentration of kinetic <span class="hlt">hydrate</span> inhibitors, polyvinylpyrrolidone (PVP), and polyvinylcaprolactam (PVCap) on the onset and growth of synthetic natural gas <span class="hlt">hydrates</span> is investigated by measuring the <span class="hlt">hydrate</span> onset time and gas consumption rate. Although the <span class="hlt">hydrate</span> onset time is extended by increasing the concentration from 0.5 to 3.0 wt % for both PVP and PVCap, the growth rate of <span class="hlt">hydrates</span> shows that the different tendency depends on the type of kinetic <span class="hlt">hydrate</span> inhibitor and its concentration. For PVCap solution, the <span class="hlt">hydrate</span> growth was slow for more than 1000 min after the onset at the concentration of 0.5 and 1.5 wt %. However, the growth rate becames almost 8 times faster at the concentration of 3.0 wt %, representing the catastrophic growth of <span class="hlt">hydrate</span> just after the <span class="hlt">hydrate</span> onset. (13)C NMR spectra of <span class="hlt">hydrates</span> formed at 3.0 wt % of PVP and PVCap indicate the existence of both structures I and II. Cage occupancy of methane in large cages of structure II decreases significantly when compared to that for pure water. These results suggest that increasing the concentration of KHI up to 3.0 wt % may induce the earlier appearance of catastrophic <span class="hlt">hydrate</span> growth and the existence of metastable structure I; thus, there needs to be an upper limit for using KHI to manage the formation of gas <span class="hlt">hydrates</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=Nitrates&pg=2&id=EJ936775','ERIC'); return false;" href="http://eric.ed.gov/?q=Nitrates&pg=2&id=EJ936775"><span>Waters of <span class="hlt">Hydration</span> of Cupric <span class="hlt">Hydrates</span>: A Comparison between Heating and Absorbance Methods</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Barlag, Rebecca; Nyasulu, Frazier</p> <p>2011-01-01</p> <p>The empirical formulas of four cupric <span class="hlt">hydrates</span> are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown <span class="hlt">hydrate</span> is prepared by using 0.2-0.3 g of <span class="hlt">hydrate</span>, and water is added such…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4817432','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4817432"><span>Phylogenetic origin of <span class="hlt">limes</span> and lemons revealed by cytoplasmic and nuclear markers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Curk, Franck; Ollitrault, Frédérique; Garcia-Lor, Andres; Luro, François; Navarro, Luis; Ollitrault, Patrick</p> <p>2016-01-01</p> <p>Background and Aims The origin of <span class="hlt">limes</span> and lemons has been a source of conflicting taxonomic opinions. Biochemical studies, numerical taxonomy and recent molecular studies suggested that cultivated Citrus species result from interspecific hybridization between four basic taxa (C. reticulata, C. maxima, C. medica and C. micrantha). However, the origin of most lemons and <span class="hlt">limes</span> remains controversial or unknown. The aim of this study was to perform extended analyses of the diversity, genetic structure and origin of <span class="hlt">limes</span> and lemons. Methods The study was based on 133 Citrus accessions. It combined maternal phylogeny studies based on mitochondrial and chloroplastic markers, and nuclear structure analysis based on the evaluation of ploidy level and the use of 123 markers, including 73 basic taxa diagnostic single nucleotide polymorphism (SNP) and indel markers. Key Results The <span class="hlt">lime</span> and lemon horticultural group appears to be highly polymorphic, with diploid, triploid and tetraploid varieties, and to result from many independent reticulation events which defined the sub-groups. Maternal phylogeny involves four cytoplasmic types out of the six encountered in the Citrus genus. All <span class="hlt">lime</span> and lemon accessions were highly heterozygous, with interspecific admixture of two, three and even the four ancestral taxa genomes. Molecular polymorphism between varieties of the same sub-group was very low. Conclusions Citrus medica contributed to all <span class="hlt">limes</span> and lemons and was the direct male parent for the main sub-groups in combination with C. micrantha or close papeda species (for C. aurata, C. excelsa, C. macrophylla and C. aurantifolia – ‘Mexican’ <span class="hlt">lime</span> types of Tanaka’s taxa), C. reticulata (for C. limonia, C. karna and C. jambhiri varieties of Tanaka’s taxa, including popular citrus rootstocks such as ‘Rangpur’ <span class="hlt">lime</span>, ‘Volkamer’ and ‘Rough’ lemons), C. aurantium (for C. limetta and C. limon – yellow lemon types – varieties of Tanaka’s taxa) or the C. maxima</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JHyd..386...80Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JHyd..386...80Z"><span>A coupled THMC model of a heating and <span class="hlt">hydration</span> laboratory experiment in unsaturated compacted FEBEX bentonite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, Liange; Samper, Javier; Montenegro, Luis; Fernández, Ana María</p> <p>2010-05-01</p> <p>SummaryUnsaturated compacted bentonite is foreseen by several countries as a backfill and sealing material in high-level radioactive waste repositories. The strong interplays between thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the <span class="hlt">hydration</span> stage of a repository call for fully coupled THMC models. Validation of such THMC models is prevented by the lack of comprehensive THMC experiments and the difficulties of experimental methods to measure accurately the chemical composition of bentonite porewater. We present here a non-isothermal multiphase flow and multicomponent reactive solute transport model for a deformable medium of a heating and <span class="hlt">hydration</span> experiment performed on a sample of compacted FEBEX bentonite. Besides standard solute transport and geochemical processes, the model accounts for solute cross diffusion and thermal and chemical osmosis. Bentonite swelling is solved with a state-surface approach. The THM model is calibrated with transient temperature, water content and porosity data measured at the end of the experiment. The reactive transport model is calibrated with porewater chemical data derived from aqueous extract data. Model results confirm that thermal osmosis is relevant for the <span class="hlt">hydration</span> of FEBEX bentonite while chemical osmosis can be safely neglected. Dilution and evaporation are the main processes controlling the concentration of conservative species. Dissolved cations are mostly affected by <span class="hlt">calcite</span> dissolution-precipitation and cation exchange reactions. Dissolved sulphate is controlled by gypsum/anhydrite dissolution-precipitation. pH is mostly buffered by protonation/deprotonation via surface complexation. Computed concentrations agree well with inferred aqueous extract data at all sections except near the <span class="hlt">hydration</span> boundary where cation data are affected by a sampling artifact. The fit of Cl - data is excellent except for the data near the heater. The largest deviations of the model from inferred</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/985334','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/985334"><span>A coupled THMC model of a heating and <span class="hlt">hydration</span> laboratory experiment in unsaturated compacted FEBEX bentonite</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zheng, L.; Samper, J.; Montenegro, L.; Fernandez, A.M.</p> <p>2010-05-01</p> <p>Unsaturated compacted bentonite is foreseen by several countries as a backfill and sealing material in high-level radioactive waste repositories. The strong interplays between thermal (T), hydrodynamic (H), mechanical (M) and chemical (C) processes during the <span class="hlt">hydration</span> stage of a repository call for fully coupled THMC models. Validation of such THMC models is prevented by the lack of comprehensive THMC experiments and the difficulties of experimental methods to measure accurately the chemical composition of bentonite porewater. We present here a non-isothermal multiphase flow and multicomponent reactive solute transport model for a deformable medium of a heating and <span class="hlt">hydration</span> experiment performed on a sample of compacted FEBEX bentonite. Besides standard solute transport and geochemical processes, the model accounts for solute cross diffusion and thermal and chemical osmosis. Bentonite swelling is solved with a state-surface approach. The THM model is calibrated with transient temperature, water content and porosity data measured at the end of the experiment. The reactive transport model is calibrated with porewater chemical data derived from aqueous extract data. Model results confirm that thermal osmosis is relevant for the <span class="hlt">hydration</span> of FEBEX bentonite while chemical osmosis can be safely neglected. Dilution and evaporation are the main processes controlling the concentration of conservative species. Dissolved cations are mostly affected by <span class="hlt">calcite</span> dissolution-precipitation and cation exchange reactions. Dissolved sulphate is controlled by gypsum/anhydrite dissolution-precipitation. pH is mostly buffered by protonation/deprotonation via surface complexation. Computed concentrations agree well with inferred aqueous extract data at all sections except near the <span class="hlt">hydration</span> boundary where cation data are affected by a sampling artifact. The fit of Cl{sup -} data is excellent except for the data near the heater. The largest deviations of the model from inferred aqueous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..MARD39015E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..MARD39015E"><span>Enhancing mechanical properties of <span class="hlt">calcite</span> by Mg substitutions: An ab initio study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elstnerova, Pavlina; Friak, Martin; Hickel, Tilmann; Fabritius, Helge Otto; Lymperakis, Liverios; Petrov, Michal; Raabe, Dierk; Neugebauer, Joerg; Nikolov, Svetoslav; Zigler, Andreas; Hild, Sabine</p> <p>2011-03-01</p> <p>Arthropoda representing a majority of all known animal species are protected by an exoskeleton formed by their cuticle. The cuticle represents a hierarchically structured multifunctional bio-composite based on chitin and proteins. Some groups like Crustacea reinforce the load-bearing parts of their cuticle with <span class="hlt">calcite</span>. As the <span class="hlt">calcite</span> sometimes contains Mg it was speculated that Mg may have a stiffening impact on the mechanical properties of the cuticle. We present a theoretical parameter-free quantum-mechanical study of thermodynamic, structural and elastic properties of Mg-substituted <span class="hlt">calcite</span>. Our results show that substituting Ca by Mg causes an almost linear decrease in the crystal volume with Mg concentration and of substituted crystals. As a consequence the <span class="hlt">calcite</span> crystals become stiffer giving rise e.g. to substantially increased bulk moduli.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23493708','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23493708"><span>Flexible minerals: self-assembled <span class="hlt">calcite</span> spicules with extreme bending strength.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Natalio, Filipe; Corrales, Tomas P; Panthöfer, Martin; Schollmeyer, Dieter; Lieberwirth, Ingo; Müller, Werner E G; Kappl, Michael; Butt, Hans-Jürgen; Tremel, Wolfgang</p> <p>2013-03-15</p> <p>Silicatein-α is responsible for the biomineralization of silicates in sponges. We used silicatein-α to guide the self-assembly of <span class="hlt">calcite</span> "spicules" similar to the spicules of the calcareous sponge Sycon sp. The self-assembled spicules, 10 to 300 micrometers (μm) in length and 5 to 10 μm in diameter, are composed of aligned <span class="hlt">calcite</span> nanocrystals. The spicules are initially amorphous but transform into <span class="hlt">calcite</span> within months, exhibiting unusual growth along [100]. They scatter x-rays like twinned <span class="hlt">calcite</span> crystals. Whereas natural spicules evidence brittle failure, the synthetic spicules show an elastic response, which greatly enhances bending strength. This remarkable feature is linked to a high protein content. With nano-thermogravimetric analysis, we measured the organic content of a single spicule to be 10 to 16%. In addition, the spicules exhibit waveguiding properties even when they are bent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015615','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015615"><span>Simulation of <span class="hlt">calcite</span> dissolution and porosity changes in saltwater mixing zones in coastal aquifers</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sanford, W.E.; Konikow, L.F.</p> <p>1989-01-01</p> <p>Thermodynamic models of aqueous solutions have indicated that the mixing of seawater and <span class="hlt">calcite</span>-saturated fresh groundwater can produce a water that is undersaturated with respect to <span class="hlt">calcite</span>. Mixing of such waters in coastal carbonate aquifers could lead to significant amounts of limestone dissolution. The potential for such dissolution in coastal saltwater mixing zones is analyzed by coupling the results from a reaction simulation model (PHREEQE) with a variable density groundwater flow and solute transport model. Idealized cross sections of coastal carbonate aquifers are simulated to estimate the potential for <span class="hlt">calcite</span> dissolution under a variety of hydrologic and geochemical conditions. Results show that limestone dissolution in mixing zones is strongly dependent on groundwater flux and nearly independent of the dissolution kinetics of <span class="hlt">calcite</span>. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=calcite+OR+montmorillonite+OR+kaolinite+OR+gibbsite&id=EJ213146','ERIC'); return false;" href="http://eric.ed.gov/?q=calcite+OR+montmorillonite+OR+kaolinite+OR+gibbsite&id=EJ213146"><span>High School Forum: "Invitations to Enquiry": The <span class="hlt">Calcite</span>/Acid Reaction.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Herron, J. Dudley, Ed.; Driscoll, D. R.</p> <p>1979-01-01</p> <p>Describes a high school chemistry experiment which involves the reaction between <span class="hlt">calcite</span> and hydrochloric and sulfuric acids. This reaction can be carried out as a projected demonstration and on an individual basis. (HM)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MinPe.109..453G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MinPe.109..453G"><span>Phase transformation of Mg-<span class="hlt">calcite</span> to aragonite in active-forming hot spring travertines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Greer, Heather F.; Zhou, Wuzong; Guo, Li</p> <p>2015-08-01</p> <p>A travertine specimen collected from the western part of Yunnan Province of China was subjected to microstructural analysis by powder X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. A new formation mechanism was proposed whereby polycrystalline rhombohedral particles of magnesium-containing <span class="hlt">calcite</span> underwent a phase transformation into sheaf-like clusters of aragonite microrods. It is proposed that a high concentration of magnesium ions and embedded biological matter poisoned the growth of <span class="hlt">calcite</span> and therefore instigated the phase transformation of the core of the rhombohedral <span class="hlt">calcite</span> particles to an aragonite phase with a higher crystallinity. The single crystalline aragonite microrods with a higher density than the Mg-<span class="hlt">calcite</span> nanocrystallites grew at the expense of the latter to generate sheaf-like clusters. This newly discovered formation mechanism is expected to enhance previous knowledge on this geologically important phase transformation from a morphology point of view.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12742051','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12742051"><span>Polymer coatings to passivate <span class="hlt">calcite</span> from acid attack: polyacrylic acid and polyacrylonitrile.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thompson, Mary; Wilkins, Shelley J; Compton, Richard G; Viles, Heather A</p> <p>2003-04-01</p> <p>The extent of passivation of <span class="hlt">calcite</span> toward dissolution by aqueous acids arising from polymeric coatings based on polyacrylic acid or polyacrylonitrile is evaluated using a channel flow cell technique with microdisc electrode detection. In situ passivation with polyacrylic acid leads to a reduction in the reactivity of <span class="hlt">calcite</span> toward acid attack with a reduction in the rate constant by up to an order of magnitude compared with untreated <span class="hlt">calcite</span>. Ex situ passivation with polyacrylic acid for 24 h results in good coverage of the <span class="hlt">calcite</span> by the polymer but it is shown to erode from the surface when exposed to an aqueous acid solution. In contrast, polyacrylonitrile is demonstrated to form a regular coating after exposure for just 1 h and offers robust potent protection from aqueous acid attack.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCrGr.457..356C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCrGr.457..356C"><span>Morphological changes of <span class="hlt">calcite</span> single crystals induced by graphene-biomolecule adducts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Calvaresi, Matteo; Di Giosia, Matteo; Ianiro, Alessandro; Valle, Francesco; Fermani, Simona; Polishchuk, Iryna; Pokroy, Boaz; Falini, Giuseppe</p> <p>2017-01-01</p> <p><span class="hlt">Calcite</span> has the capability to interact with a wide variety of molecules. This usually induces changes in shape and morphology of crystals. Here, this process was investigated using sheets of graphene-biomolecule adducts. They were prepared and made dispersible in water through the exfoliation of graphite by tip sonication in the presence tryptophan or N-acetyl-D-glucosamine. The crystallization of calcium carbonate in the presence of these additives was obtained by the vapor diffusion method and only <span class="hlt">calcite</span> formed. The analysis of the microscopic observations showed that the graphene-biomolecule adducts affected shape and morphology of rhombohedral {10.4} faced <span class="hlt">calcite</span> crystals, due to their stabilization of additional {hk.0} faces. The only presence of the biomolecule affected minimally shape and morphology of <span class="hlt">calcite</span> crystals, highlighting the key role of the graphene sheets as 2D support for the adsorption of the biomolecules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/913015','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/913015"><span>Methane <span class="hlt">hydrate</span> research at NETL: Research to make methane production from <span class="hlt">hydrates</span> a reality</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Taylor, C.E.; Link, D.D.; English, N.</p> <p>2007-03-01</p> <p>Research is underway at NETL to understand the physical properties of methane <span class="hlt">hydrates</span>. Five key areas of research that need further investigation have been identified. These five areas, i.e. thermal properties of <span class="hlt">hydrates</span> in sediments, kinetics of natural <span class="hlt">hydrate</span> dissociation, hysteresis effects, permeability of sediments to gas flow and capillary pressures within sediments, and <span class="hlt">hydrate</span> distribution at porous scale, are important to the production models that will be used for producing methane from <span class="hlt">hydrate</span> deposits. NETL is using both laboratory experiments and computational modeling to address these five key areas. The laboratory and computational research reinforce each other by providing feedback. The laboratory results are used in the computational models and the results from the computational modeling is used to help direct future laboratory research. The data generated at NETL will be used to help fulfill The National Methane <span class="hlt">Hydrate</span> R&D Program of a “long-term supply of natural gas by developing the knowledge and technology base to allow commercial production of methane from domestic <span class="hlt">hydrate</span> deposits by the year 2015” as outlined on the NETL Website [NETL Website, 2005. http://www.netl.doe.gov/scngo/Natural%20Gas/<span class="hlt">hydrates</span>/index.html]. Laboratory research is accomplished in one of the numerous high-pressure <span class="hlt">hydrate</span> cells available ranging in size from 0.15 mL to 15 L in volume. A dedicated high-pressure view cell within the Raman spectrometer allows for monitoring the formation and dissociation of <span class="hlt">hydrates</span>. Thermal conductivity of <span class="hlt">hydrates</span> (synthetic and natural) at a certain temperature and pressure is performed in a NETL-designed cell. Computational modeling studies are investigating the kinetics of <span class="hlt">hydrate</span> formation and dissociation, modeling methane <span class="hlt">hydrate</span> reservoirs, molecular dynamics simulations of <span class="hlt">hydrate</span> formation, dissociation, and thermal properties, and Monte Carlo simulations of <span class="hlt">hydrate</span> formation and dissociation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711145C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711145C"><span>The Influence of <span class="hlt">Calcite</span> on The Mechanical Behavior of Quartz-Bearing Gouge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carpenter, Brett; Di Stefano, Giuseppe; Collettini, Cristiano</p> <p>2015-04-01</p> <p>Mechanical heterogeneities along faults can result in diverse and complex fault slip. These heterogeneities can vary spatially and temporally and may result from changes in fault structure or frictional properties. The accumulation of <span class="hlt">calcite</span> in non-carbonate faults, via cementation or entrainment, is likely to alter the frictional properties of that fault gouge. Furthermore, widespread observations of <span class="hlt">calcite</span> as cement, veins, or cataclasites in non-carbonate hosted faults indicates that <span class="hlt">calcite</span> is readily available and could play an important role during fault reactivation at shallow- and mid-crustal earthquakes. We report on laboratory experiments designed to explore the mechanical behavior of quartz/<span class="hlt">calcite</span> mixtures as a means to better understand the evolution in behavior of quartz-bearing gouge in the presence of exotic <span class="hlt">calcite</span>. We sheared mixtures of powdered Carrara marble (>98% CaCO3) and disaggregated Ottawa sand (99.8% SiO2) at constant normal stresses of 5 and 50 MPa under saturated conditions at room temperature. We performed slide-hold-slide tests, 1-3,000 seconds, and velocity stepping tests, 0.1-1000 µm/s, to measure the amount of frictional healing and velocity dependence of friction respectively. At low normal stress, the addition of <span class="hlt">calcite</span> to quartz-based synthetic fault gouge results in increases in the steady-state frictional strength, and rates of frictional healing and creep relaxation of the gouge. In particular, with the addition of as little as 2.5 wt% <span class="hlt">calcite</span>, the frictional healing rate increases by 30%. Microstructural observations indicate that shear is accommodated by distributed deformation throughout the gouge layer and that <span class="hlt">calcite</span> undergoes significantly more comminution compared to quartz. Large quartz grains frequently show minor rounding of angular edges with fine-grained <span class="hlt">calcite</span> often penetrating fractures. The in-situ addition of <span class="hlt">calcite</span> to fault gouge, by either the circulation of fluids or the involvement of carbonate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T22C..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T22C..01C"><span>The Influence of Exotic <span class="hlt">Calcite</span> on the Mechanical Behavior of Quartz Bearing Fault Gouge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carpenter, B. M.; Di Stefano, G.; Collettini, C.</p> <p>2014-12-01</p> <p>The interseismic recovery of frictional strength is a fundamental part of the seismic cycle. This restrengthening, and related phenomena, plays a key role in determining the stability and mode of tectonic faulting. Recent experimental data has shown that gouge mineralogy has a strong influence on the rate of frictional healing, with <span class="hlt">calcite</span>-dominated gouges showing the highest rates. Combining these data with widespread observations of <span class="hlt">calcite</span> as cement or veins in non-carbonate hosted faults, indicates that the presence of <span class="hlt">calcite</span> within a fault gouge could play an important role in shallow- and mid-crustal earthquakes. We report on laboratory experiments designed to explore the mechanical behavior of quartz/<span class="hlt">calcite</span> mixtures as a means to better understand the evolution of fault behavior in faults where carbonate materials are present. We sheared mixtures of powdered Carrara marble (>98% CaCO3) and disaggregated Ottawa sand (99.8% SiO2) at constant normal stress of 5 MPa under saturated conditions at room temperature. We performed slide-hold-slide tests, 1-3,000 seconds, and velocity stepping tests, 0.1-1000 μm/s, to measure the amount of frictional healing and velocity dependence of friction respectively. Small subsets of experiments were conducted at different boundary conditions. Preliminary results show that the presence of <span class="hlt">calcite</span> in quartz-based fault gouge has a hardening effect, both in overall frictional strength, where the strength of our mixtures increases with increasing <span class="hlt">calcite</span> content, and in single experiments, where mixtures with low percentages of <span class="hlt">calcite</span> show a consistent strain-hardening trend. We also observe that the rates of frictional healing and creep relaxation increase with increasing <span class="hlt">calcite</span> content. Finally, our results show that the addition of as little as 2.5% <span class="hlt">calcite</span> within a fault gouge results in a 30% increase in the rate of frictional healing, with further increases in <span class="hlt">calcite</span> content resulting in larger increases in the rate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985GeCoA..49..713B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985GeCoA..49..713B"><span>Kinetic and thermodynamic factors controlling the distribution of SO 32- and Na + in <span class="hlt">calcites</span> and selected aragonites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Busenberg, Eurybiades; Niel Plummer, L.</p> <p>1985-03-01</p> <p>Significant amounts of SO 42-, Na +, and OH - are incorporated in marine biogenic <span class="hlt">calcites</span>. Biogenic high Mg-<span class="hlt">calcites</span> average about 1 mole percent SO 42-. Aragonites and most biogenic low Mg-<span class="hlt">calcites</span> contain significant amounts of Na +, but very low concentrations of SO 42-. The SO 42- content of non-biogenic <span class="hlt">calcites</span> and aragonites investigated was below 100 ppm. The presence of Na + and SO 42- increases the unit cell size of <span class="hlt">calcites</span>. The solid-solutions show a solubility minimum at about 0.5 mole percent SO 42- beyond which the solubility rapidly increases. The solubility product of <span class="hlt">calcites</span> containing 3 mole percent SO 42- is the same as that of aragonite. Na + appears to have very little effect on the solubility product of <span class="hlt">calcites</span>. The amounts of Na + and SO 42- incorporated in <span class="hlt">calcites</span> vary as a function of the rate of crystal growth. The variation of the distribution coefficient ( D) of SO 42- in <span class="hlt">calcite</span> at 25.0°C and 0.50 molal NaCl is described by the equation D = k 0 + k 1R where k 0 and k 1 are constants equal to 6.16 × 10 -6 and 3.941 × 10 -6, respectively, and R is the rate of crystal growth of <span class="hlt">calcite</span> in mg·min -1·g -1 of seed. The data on Na + are consistent with the hypothesis that a significant amount of Na + occupies interstitial positions in the <span class="hlt">calcite</span> structure. The distribution of Na + follows a Freundlich isotherm and not the Berthelot-Nernst distribution law. The numerical value of the Na + distribution coefficient in <span class="hlt">calcite</span> is probably dependent on the number of defects in the <span class="hlt">calcite</span> structure. The Na + contents of <span class="hlt">calcites</span> are not very accurate indicators of environmental salinities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70012943','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70012943"><span>Kinetic and thermodynamic factors controlling the distribution of SO32- and Na+ in <span class="hlt">calcites</span> and selected aragonites</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Busenberg, E.; Niel, Plummer L.</p> <p>1985-01-01</p> <p>Significant amounts of SO42-, Na+, and OH- are incorporated in marine biogenic <span class="hlt">calcites</span>. Biogenic high Mg-<span class="hlt">calcites</span> average about 1 mole percent SO42-. Aragonites and most biogenic low Mg-<span class="hlt">calcites</span> contain significant amounts of Na+, but very low concentrations of SO42-. The SO42- content of non-biogenic <span class="hlt">calcites</span> and aragonites investigated was below 100 ppm. The presence of Na+ and SO42- increases the unit cell size of <span class="hlt">calcites</span>. The solid-solutions show a solubility minimum at about 0.5 mole percent SO42- beyond which the solubility rapidly increases. The solubility product of <span class="hlt">calcites</span> containing 3 mole percent SO42- is the same as that of aragonite. Na+ appears to have very little effect on the solubility product of <span class="hlt">calcites</span>. The amounts of Na+ and SO42- incorporated in <span class="hlt">calcites</span> vary as a function of the rate of crystal growth. The variation of the distribution coefficient (D) of SO42- in <span class="hlt">calcite</span> at 25.0??C and 0.50 molal NaCl is described by the equation D = k0 + k1R where k0 and k1 are constants equal to 6.16 ?? 10-6 and 3.941 ?? 10-6, respectively, and R is the rate of crystal growth of <span class="hlt">calcite</span> in mg??min-1??g-1 of seed. The data on Na+ are consistent with the hypothesis that a significant amount of Na+ occupies interstitial positions in the <span class="hlt">calcite</span> structure. The distribution of Na+ follows a Freundlich isotherm and not the Berthelot-Nernst distribution law. The numerical value of the Na+ distribution coefficient in <span class="hlt">calcite</span> is probably dependent on the number of defects in the <span class="hlt">calcite</span> structure. The Na+ contents of <span class="hlt">calcites</span> are not very accurate indicators of environmental salinities. ?? 1985.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6641100','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6641100"><span><span class="hlt">Calcite</span> genesis in the Upper Freeport coal bed as indicated by stable isotope geochemistry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dulong, F.T.; Spiker, E.C.; Cecil, C.B.; Stanton, R.W.</p> <p>1985-01-01</p> <p>The grinding and sizing in float-sink testing of the Upper Freeport coal bed physically separates <span class="hlt">calcite</span> of different origins. The different origins are distinguished by different isotopic compositions. The isotopic compositions of <span class="hlt">calcite</span> indicates at least two, possibly three, stages of <span class="hlt">calcite</span> formation in the Upper Freeport coal bed. <span class="hlt">Calcite</span> samples obtained from cleat, and isolated from 8x100 mesh-1.8 specific gravity sink fraction and -100 mesh size fraction, are enriched in /sup 13/C. The dispersion in /sup 18/O values for all three sample types, as measured by the standard deviation, is 2.7 per mil relative to SMOW, which may indicate similar temperature of formation. In contrast, <span class="hlt">calcite</span> from the 1.275 specific gravity float fraction is depleted in /sup 13/C (mean = -4.6 per mil), indicative of CO/sub 2/ generated from the oxidation of organic matter. The standard deviation of /sup 18/O values for these samples is 9.2 per mil, probably indicating variation in the temperature of formation. Limestone samples associated with the Upper Freeport coal bed are slightly depleted in /sup 13/C (mean = -3.1 per mil). Genesis of <span class="hlt">calcite</span> in the coal apparently resulted from biotic, as well as, thermogenic processes. A second stage of <span class="hlt">calcite</span> formation, resulting from fermentation and methanogenesis is in cleat, and in the 8x100 mesh-1.8 specific gravity sink and -100 mesh size fractions. Part of the <span class="hlt">calcite</span> in the 1.275 specific gravity float fraction may have formed from thermally generated CO/sub 2/ released during coalification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeCoA.197..226P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeCoA.197..226P"><span>The coordination of sulfur in synthetic and biogenic Mg <span class="hlt">calcites</span>: The red coral case</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perrin, J.; Rivard, C.; Vielzeuf, D.; Laporte, D.; Fonquernie, C.; Ricolleau, A.; Cotte, M.; Floquet, N.</p> <p>2017-01-01</p> <p>Sulfur has been recognized in biogenic <span class="hlt">calcites</span> for a long time. However, its structural position is matter of debate. For some authors, sulfur is a marker of the organic matrix while it is part of the <span class="hlt">calcite</span> structure itself for others. To better understand the place of sulfur in <span class="hlt">calcite</span>, sulfated magnesian <span class="hlt">calcites</span> (S-Mg<span class="hlt">Calcite</span>) have been synthetized at high pressure and temperature and studied by μ-XANES spectroscopy. S-Mg<span class="hlt">Calcite</span> XANES spectra show two different types of sulfur: sulfate (SO42-) as a predominant species and a small contribution of sulfite (SO32-), both substituting for carbonate ions in the <span class="hlt">calcite</span> structure. To address the question of the position of sulfur in biogenic <span class="hlt">calcites</span>, the oxidation states of sulfur in the skeleton and organic tissues of Corallium rubrum have been investigated by micro X-ray fluorescence (μ-XRF) and sulfur K-edge micro X-ray absorption near edge structure (μ-XANES) spectroscopy at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) on beamline ID21. In the skeleton, sulfur is mainly present as oxidized sulfur SO42- (+VI), plus a weak sulfite contribution. XANES spectra indicate that sulfur is inorganically incorporated as sulfur structurally substituted to carbonate ions (SSS). Although an organic matrix is present in the red coral skeleton, reduced organic sulfur could not be detected by μ-XANES spectroscopy in the skeleton probably due to low organic/inorganic sulfur ratio. In the organic tissues surrounding the skeleton, several sulfur oxidation states have been detected including disulfide (S-S), thioether (R-S-CH3), sulfoxide (SO2), sulfonate (SO2O-) and sulfate (SO42-). The unexpected occurrence of inorganic sulfate within the organic tissues suggests the presence of pre-organized organic/inorganic complexes in the circulatory system of the red coral, precursors to biomineralization ahead of the growth front.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029387','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029387"><span>The <span class="hlt">calcite</span> → aragonite transformation in low-Mg marble: Equilibrium relations, transformations mechanisms, and rates</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hacker, Bradley R.; Rubie, David C.; Kirby, Stephen H.; Bohlen, Steven R.</p> <p>2005-01-01</p> <p>Experimental transformation of a rather pure natural <span class="hlt">calcite</span> marble to aragonite marble did not proceed via the expected straightforward polymorphic replacement. Instead, the small amount of Mg in the starting material (0.36 wt %) was excluded from the growing aragonite and diffused preferentially into the remaining <span class="hlt">calcite</span> grains, producing Mg-rich <span class="hlt">calcite</span> rods that persisted as relicts. Nucleation of aragonite occurred exclusively on grain boundaries, with aragonite [001] oriented subparallel to <span class="hlt">calcite</span> [0001]. The aragonite crystals preferentially consumed the <span class="hlt">calcite</span> crystal on which they nucleated, and the reaction fronts developed preferentially along the {010} and {110} planes of aragonite. Each aragonite neoblast that grew was nearly free of Mg (typically <0.1 wt %). The excess Mg was taken up by the <span class="hlt">calcite</span> grains in between, stabilizing them and causing a few volume percent rodlike relicts of Mg-enriched <span class="hlt">calcite</span> (up to 10 wt % MgO) to be left behind by the advancing reaction front. The aragonite growth rates are approximately linear and range from ∼3 × 10−11 m s−1 at 600°C to ∼9 × 10−9 m s−1 at 850°C, with an apparent activation enthalpy of 166 ± 91 kJ mol−1. This reaction mechanism and the resultant texture are akin to cellular precipitation reactions in metals. Similar transformation textures have been reported from high-Mg marbles in Japan and China that disproportionated to low-Mg <span class="hlt">calcite</span> and dolomite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1005573','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1005573"><span>Effects of chitosan on the alignment, morphology and shape of <span class="hlt">calcite</span> crystals nucleating under Langmuir monolayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, Kyungil; Uysal, Ahmet; Kewalramani, Sumit; Stripe, Benjamin; Dutta, Pulak</p> <p>2009-04-22</p> <p>The growth of calcium carbonate crystals under Langmuir monolayers was investigated in the presence of chitosan, a soluble derivative of chitin added to the subphase to better simulate the polyelectrolyte-containing in vivo environment. Chitosan causes distinct concentration-dependent changes in the orientation, shape and morphology of the <span class="hlt">calcite</span> crystals nucleating under acid and sulfate monolayers. Our results suggest that polyelectrolytes may play essential roles in controlling the growth of biogenic <span class="hlt">calcite</span> crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/980170','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/980170"><span>Effects of Chitosan on the Morphology and Alignment of <span class="hlt">Calcite</span> Crystals Nucleating Under Langmuir Monolayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, K.; Uysal, A; Kewalramani, S; Stripe, B; Dutta, P</p> <p>2009-01-01</p> <p>The growth of calcium carbonate crystals under Langmuir monolayers was investigated in the presence of chitosan, a soluble derivative of chitin added to the subphase to better simulate the polyelectrolyte-containing in vivo environment. Chitosan causes distinct concentration-dependent changes in the orientation, shape and morphology of the <span class="hlt">calcite</span> crystals nucleating under acid and sulfate monolayers. Our results suggest that polyelectrolytes may play essential roles in controlling the growth of biogenic <span class="hlt">calcite</span> crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15276741','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15276741"><span><span class="hlt">Liming</span> as an advanced treatment for sludge sanitisation: helminth eggs elimination--Ascaris eggs as model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Capizzi-Banas, S; Deloge, M; Remy, M; Schwartzbrod, J</p> <p>2004-01-01</p> <p>The presence of helminth eggs (Ascaris eggs) in sewage sludge may constitute a sanitary risk when used as agricultural fertiliser. Sanitisation of sewage sludge can be achieved by treatment with quick <span class="hlt">lime</span>, a process that destroys sludge pathogens in two ways: pH increase and temperature rise. Among the pathogens of epidemiological relevance, Ascaris eggs are the most resistant to <span class="hlt">liming</span>, and, hence, may serve as indicators of hygienic quality of biosolids. This research aims at defining, between 50 degrees C and 60 degrees C, the time required in the case of <span class="hlt">limed</span> sludge to obtain a product with a negligible level of viable Ascaris eggs. To achieve this objective, investigations on inactivation kinetics of Ascaris eggs were conducted in the following products: contaminated milk of <span class="hlt">lime</span>; naturally contaminated sludge treated with slaked <span class="hlt">lime</span> and heat; naturally contaminated sludge treated with quick <span class="hlt">lime</span>; and sludge treated at full scale with quick <span class="hlt">lime</span>. For the inactivation kinetics where a negligible level of Ascaris eggs was reached, the inactivation threshold was determined. Depending on the experimental situation, the inactivation threshold period was found to fluctuate between 5 and 75 min at 55 degrees C and between 1 and 8 min at 60 degrees C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15279099','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15279099"><span>Improving primary treatment of urban wastewater with <span class="hlt">lime</span>-induced coagulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Marani, Dario; Ramadori, Roberto; Braguglia, Camilla Maria</p> <p>2004-01-01</p> <p>The enhancement of primary treatment efficiency through the coagulation process may yield several advantages, including lower aeration energy in the subsequent biological unit and higher recovery of biogas from sludge digestion. In this work sewage coagulation with <span class="hlt">lime</span> was studied at pilot plant level, using degritted sewage from the city of Rome. The work aimed at optimising the operating conditions (coagulant dosage or treatment pH, and mixing conditions in the coagulation and flocculation tanks), in order to maximise the efficiency of suspended Chemical Oxygen Demand (COD) removal and to minimise sludge production. <span class="hlt">Lime</span> dosage optimisation resulted in an optimal treatment pH of 9. <span class="hlt">Lime</span> addition up to pH 9 may increase COD removal rate in the primary treatment from typical 30-35% of plain sedimentation up to 55-70%. Within the velocity gradients experimented in this work (314-795 s(-1) for the coagulation tank and 13-46 s(-1) for the flocculation tank), mixing conditions did not significantly affect the <span class="hlt">lime</span>-enhanced process, which seems to be controlled by slow <span class="hlt">lime</span> dissolution. Sludge produced in the <span class="hlt">lime</span>-enhanced process settled and compacted easily, inducing an average 36% decrease in sludge volume with respect to plain settling. However excess sludge was produced, which was not accounted for by the amount of suspended solids removed. This is probably due to incomplete dissolution of <span class="hlt">lime</span>, which may be partially incorporated in the sludge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15093062','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15093062"><span>Effects of <span class="hlt">lime</span> amendment on availability of heavy metals and maturation in sewage sludge composting.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fang, M; Wong, J W</p> <p>1999-07-01</p> <p>A batch composting study was performed to evaluate the feasibility of co-composting sewage sludge with <span class="hlt">lime</span>, aiming at reducing the availability of heavy metals in the sludge compost. Sewage sludge with sawdust as bulking agent was amended with <span class="hlt">lime</span> at 0, 0.63, 1.0, and 1.63% w/w, and composted for 100 days in laboratory batch reactors. The changes in temperature, pH, electrical conductivity (EC), and extractable heavy metal contents were measured while compost maturity was determined by C/N(organic) and cress seed germination during the composting period. <span class="hlt">Liming</span> raised pH of compost effectively at the initial stage of composting and caused a decrease in EC through precipitation of soluble ions. <span class="hlt">Lime</span> amendment also significantly reduced water-soluble and Diethylene triamine pentracetic acid (DTPA)-extractable metal contents. The maximum reductions were 60 and 40% for Cu, 80 and 40% for Mn, 55 and 10% for Zn, and 20 and 25% for Ni at the end of the composting period for the <span class="hlt">lime</span>-amended sludge as compared to the control. In spite of the inhibitory effect of <span class="hlt">lime</span> amendment on the decomposition activity of sewage sludge, all treatments reached maturation after 63 days of composting as indicated by the results of C/N(organic) ratio and cress seed germination test results. A <span class="hlt">lime</span> amendment of < or =1.0% is recommended to co-compost with sewage sludge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21149608','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21149608"><span>Stabilization of Oklahoma expensive soils using <span class="hlt">lime</span> and class C fly ash</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buhler, R.L.; Cerato, A.B.</p> <p>2007-01-15</p> <p>This study uses <span class="hlt">lime</span> and class C fly ash, an industrial byproduct of electric power production produced from burning lignite and subbituminous coal, to study the plasticity reduction in highly expensive natural clays from Idabel, Oklahoma. This study is important, especially in Oklahoma, because most of the native soils are expansive and cause seasonal damage to roadways and structures. The addition of <span class="hlt">lime</span> or fly ash helps to arrest the shrinkage and swelling behavior of soil. Four soil samples with the same AASHTO classification were used in this study to show shrinkage variability within a soil group with the addition of <span class="hlt">lime</span> and class C fly ash. The plasticity reduction in this study was quantified using the linear shrinkage test. It was found that soils classified within the same AASHTO group had varying shrinkage characteristics. It was also found that both <span class="hlt">lime</span> and fly ash reduced the lienar shrinkage, however, the addition of <span class="hlt">lime</span> reduced the linear shrinkage to a greater degree than the same percentage of class C fly ash. Even though it takes much less <span class="hlt">lime</span> than fly ash to reduce the plasticity of a highly expansive soil, it may be less expensive to utilize fly ash, which is a waste product of electric power production. <span class="hlt">Lime</span> also has a lower unit weight than fly ash so weight percentage results may be misleading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11507892','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11507892"><span>[Wet FGD process on rotating-stream-tray tower with magnesium-enhanced <span class="hlt">lime</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, W; Wu, Z; Tan, T</p> <p>2001-05-01</p> <p>Wet flue gas desulfurization(FGD) process with magnesium-enhanced <span class="hlt">lime</span> slurry was conducted on a rotating-stream-tray tower. Changes of SO2 removal efficiency and slurry pH with time were experimentally determined. Effects of magnesium sulfate concentration were investigated and the <span class="hlt">lime</span> utilization was calculated according to experimental data. In comparison with <span class="hlt">lime</span> FGD process, adding magnesium sulfate could effectively enhance SO2 removal efficiency; when the adequate magnesium sulfate concentration was 0.2 mol/L, the removal efficiency was more than 60% with two rotating-stream-trays, while the removal efficiency of <span class="hlt">lime</span> process was only 45%. To achieve higher SO2 removal efficiency, the slurry pH should be controlled between 6.0 and 7.5. Magnesium sulfate could also promote <span class="hlt">lime</span> dissolution, slow down descent of slurry pH and increase <span class="hlt">lime</span> utilization; when magnesium sulfate concentration was 0.2 mol/L, <span class="hlt">lime</span> utilization could be increased by more than 5 percentage point under adequate conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27708478','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27708478"><span>Soil acidification and the importance of <span class="hlt">liming</span> agricultural soils with particular reference to the United Kingdom.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goulding, K W T</p> <p>2016-09-01</p> <p>Soil acidification is caused by a number of factors including acidic precipitation and the deposition from the atmosphere of acidifying gases or particles, such as sulphur dioxide, ammonia and nitric acid. The most important causes of soil acidification on agricultural land, however, are the application of ammonium-based fertilizers and urea, elemental S fertilizer and the growth of legumes. Acidification causes the loss of base cations, an increase in aluminium saturation and a decline in crop yields; severe acidification can cause nonreversible clay mineral dissolution and a reduction in cation exchange capacity, accompanied by structural deterioration. Soil acidity is ameliorated by applying <span class="hlt">lime</span> or other acid-neutralizing materials. '<span class="hlt">Liming</span>' also reduces N2O emissions, but this is more than offset by CO 2 emissions from the <span class="hlt">lime</span> as it neutralizes acidity. Because crop plants vary in their tolerance to acidity and plant nutrients have different optimal pH ranges, target soil pH values in the UK are set at 6.5 (5.8 in peaty soils) for cropped land and 6.0 (5.3 in peaty soils) for grassland. Agricultural <span class="hlt">lime</span> products can be sold as 'EC Fertiliser <span class="hlt">Liming</span> Materials' but, although vital for soil quality and agricultural production, <span class="hlt">liming</span> tends to be strongly influenced by the economics of farming. Consequently, much less <span class="hlt">lime</span> is being applied in the UK than required, and many arable and grassland soils are below optimum pH.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70170545','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70170545"><span>A new look at <span class="hlt">liming</span> as an approach to accelerate recovery from acidic deposition effects</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lawrence, Gregory B.; Burns, Douglas A.; Murray, Karen</p> <p>2016-01-01</p> <p>Acidic deposition caused by fossil fuel combustion has degraded aquatic and terrestrial ecosystems in North America for over four decades. The only management option other than emissions reductions for combating the effects of acidic deposition has been the application of <span class="hlt">lime</span> to neutralize acidity after it has been deposited on the landscape. For this reason, <span class="hlt">liming</span> has been a part of acid rain science from the beginning. However, continued declines in acidic deposition have led to partial recovery of surface water chemistry, and the start of soil recovery. <span class="hlt">Liming</span> is therefore no longer needed to prevent further damage, so the question becomes whether <span class="hlt">liming</span> would be useful for accelerating recovery of systems where improvement has lagged. As more is learned about recovering ecosystems, it has become clear that recovery rates vary with watershed characteristics and among ecosystem components. Lakes appear to show the strongest recovery, but recovery in streams is sluggish and recovery of soils appears to be in the early stages. The method in which <span class="hlt">lime</span> is applied is therefore critical in achieving the goal of accelerated recovery. Application of <span class="hlt">lime</span> to a watershed provides the advantage of increasing Ca availability and reducing or preventing mobilization of toxic Al, an outcome that is beneficial to both terrestrial and aquatic ecosystems. However, the goal should not be complete neutralization of soil acidity, which is naturally produced. <span class="hlt">Liming</span> of naturally acidic areas such as wetlands should also be avoided to prevent damage to indigenous species that rely on an acidic environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025674','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025674"><span>Estimation of past seepage volumes from <span class="hlt">calcite</span> distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Marshall, B.D.; Neymark, L.A.; Peterman, Z.E.</p> <p>2003-01-01</p> <p>Low-temperature <span class="hlt">calcite</span> and opal record the past seepage of water into open fractures and lithophysal cavities in the unsaturated zone at Yucca Mountain, Nevada, site of a proposed high-level radioactive waste repository. Systematic measurements of <span class="hlt">calcite</span> and opal coatings in the Exploratory Studies Facility (ESF) tunnel at the proposed repository horizon are used to estimate the volume of <span class="hlt">calcite</span> at each site of <span class="hlt">calcite</span> and/or opal deposition. By estimating the volume of water required to precipitate the measured volumes of <span class="hlt">calcite</span> in the unsaturated zone, seepage rates of 0.005 to 5 liters/year (l/year) are calculated at the median and 95th percentile of the measured volumes, respectively. These seepage rates are at the low end of the range of seepage rates from recent performance assessment (PA) calculations, confirming the conservative nature of the performance assessment. However, the distribution of the <span class="hlt">calcite</span> and opal coatings indicate that a much larger fraction of the potential waste packages would be contacted by this seepage than is calculated in the performance assessment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22413251','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22413251"><span>NMR characterization of hydrocarbon adsorption on <span class="hlt">calcite</span> surfaces: A first principles study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bevilaqua, Rochele C. A.; Miranda, Caetano R.; Rigo, Vagner A.; Veríssimo-Alves, Marcos</p> <p>2014-11-28</p> <p>The electronic and coordination environment of minerals surfaces, as <span class="hlt">calcite</span>, are very difficult to characterize experimentally. This is mainly due to the fact that there are relatively few spectroscopic techniques able to detect Ca{sup 2+}. Since <span class="hlt">calcite</span> is a major constituent of sedimentary rocks in oil reservoir, a more detailed characterization of the interaction between hydrocarbon molecules and mineral surfaces is highly desirable. Here we perform a first principles study on the adsorption of hydrocarbon molecules on <span class="hlt">calcite</span> surface (CaCO{sub 3} (101{sup ¯}4)). The simulations were based on Density Functional Theory with Solid State Nuclear Magnetic Resonance (SS-NMR) calculations. The Gauge-Including Projector Augmented Wave method was used to compute mainly SS-NMR parameters for {sup 43}Ca, {sup 13}C, and {sup 17}O in <span class="hlt">calcite</span> surface. It was possible to assign the peaks in the theoretical NMR spectra for all structures studied. Besides showing different chemical shifts for atoms located on different environments (bulk and surface) for <span class="hlt">calcite</span>, the results also display changes on the chemical shift, mainly for Ca sites, when the hydrocarbon molecules are present. Even though the interaction of the benzene molecule with the <span class="hlt">calcite</span> surface is weak, there is a clearly distinguishable displacement of the signal of the Ca sites over which the hydrocarbon molecule is located. A similar effect is also observed for hexane adsorption. Through NMR spectroscopy, we show that aromatic and alkane hydrocarbon molecules adsorbed on carbonate surfaces can be differentiated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5677360','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5677360"><span>Multiple origins for zoned cathodoluminescent and noncathodoluminescent <span class="hlt">calcite</span> cements in Pennsylvanian limestones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Goldstein, R.H.; Anderson, J.E.; Phares, R.A. )</p> <p>1991-03-01</p> <p>Noncathodoluminescent <span class="hlt">calcite</span> containing brightly to moderately luminescent zones is a common early cement in limestones. Three such cements in Upper Pennsylvanian limestones from different areas were studied. All three units are overlain up-section by Permian evaporites and consist of carbonate-siliciclastic 'cyclothems' in which individual cycles were subject to subaerial exposure. With such similar settings, one might predict that petrographically similar <span class="hlt">calcite</span> cements would have similar origins. In the Holder Formation (New Mexico), the zoned <span class="hlt">calcite</span> predates compaction, and cross-cutting relationships with cycle-capping paleosols show that zoned cements precipitated during 15 events of subaerial exposure. Therefore, cements precipitated from freshwater during early and repeated subaerial exposure. For the Lansing-Kansas City groups in northwestern Kansas, the zoned <span class="hlt">calcite</span> cements commonly are among the first precipitated but may postdate some compaction. All-liquid fluid inclusions indicated precipitation below about 50C, from brines of approximately 23 weight %. NaCl equivalent. The brines may have refluxed downward during deposition of Permian evaporites. A limestone of the Lansing-Kansas City groups of west-central Kansas contains early zoned <span class="hlt">calcite</span> cement that predates compaction. The cement contains all-liquid fluid inclusions indicating precipitation below about 50C. The presence of nonluminescent <span class="hlt">calcite</span> containing bright subzones is not indicative of a single diagenetic environment. Petrographically similar cements from similar settings may originate in markedly different diagenetic environments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23176816','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23176816"><span>Initial formation of <span class="hlt">calcite</span> crystals in the thin prismatic layer with the periostracum of Pinctada fucata.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suzuki, Michio; Nakayama, Seiji; Nagasawa, Hiromichi; Kogure, Toshihiro</p> <p>2013-02-01</p> <p>Although the formation mechanism of <span class="hlt">calcite</span> crystals in the prismatic layer has been studied well in many previous works, the initial state of <span class="hlt">calcite</span> formation has not been observed in detail using electron microscopes. In this study, we report that the soft prismatic layer with transparent color (the thin prismatic layer) in the tip of the fresh shell of Pinctada fucata was picked up to observe the early calcification phase. A scanning electron microscope (SEM) image showed that the growth tip of the thin prismatic layer was covered by the periostracum, which was also where the initial formation of <span class="hlt">calcite</span> crystals began. A cross-section containing the thin <span class="hlt">calcite</span> crystals in the thin prismatic layer with the periostracum was made using a focused ion beam (FIB) system. In a transmission electron microscope (TEM) observation, the thin <span class="hlt">calcite</span> crystal (thickness is about 1μm) on the periostracum was found to be a single crystal with the c-axis oriented perpendicular to the shell surface. On the other hand, many aggregated small particles consisting of bassanite crystals were observed in the periostracum suggesting the possibility that not only organic sulfate but also inorganic sulfates exist in the prismatic layer. These discoveries in the early calcification phase of the thin prismatic layer may help to clarify the mechanism of regulating the nucleation and orientation of the <span class="hlt">calcite</span> crystal in the shell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3483407','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3483407"><span>Sea urchin tooth mineralization: <span class="hlt">Calcite</span> present early in the aboral plumula</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Stock, Stuart R.; Veis, Arthur; Xiao, Xianghui; Almer, Jonathan D.; Dorvee, Jason R.</p> <p>2012-01-01</p> <p>In both vertebrate bone, containing carbonated hydroxyapatite as the mineral phase, and in invertebrate hard tissue comprised of calcium carbonate, a popular view is that the mineral phase develops from a long-lived amorphous precursor which later transforms into crystal form. Important questions linked to this popular view are: When and where is the crystallized material formed, and is amorphous solid added subsequently to the crystalline substrate? Sea urchin teeth, in which the earliest mineral forms within isolated compartments, in a time and position dependent manner, allow direct investigation of the timing of crystallization of the <span class="hlt">calcite</span> primary plates. Living teeth of the sea urchin Lytechinus variegatus, in their native coelomic fluid, were examined by high-energy synchrotron x-ray diffraction. The diffraction data show that <span class="hlt">calcite</span> is present in the most aboral portions of the plumula, representing the very earliest stages of mineralization, and that this <span class="hlt">calcite</span> has the same crystal orientation as in the more mature adoral portions of the same tooth. Raman spectroscopy of the aboral plumula confirms the initial primary plate mineral material is <span class="hlt">calcite</span> and does not detect amorphous calcium carbonate; in the more mature adoral incisal flange, it does detect a broader <span class="hlt">calcite</span> peak, consistent with two or more magnesium compositions. We hypothesize that some portion of each syncytial membrane in the plumula provides the information for nucleation of identically oriented <span class="hlt">calcite</span> crystals that subsequently develop to form the complex geometry of the single crystal sea urchin tooth. PMID:22940703</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22864212','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22864212"><span>Fabrication of microporous <span class="hlt">calcite</span> block from calcium hydroxide compact under carbon dioxide atmosphere at high temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Otsu, Akihiro; Tsuru, Kanji; Maruta, Michito; Munar, Melvin L; Matsuya, Shigeki; Ishikawa, Kunio</p> <p>2012-01-01</p> <p>Effects of carbonation temperature and compacting pressure on basic properties of <span class="hlt">calcite</span> block were studied using Ca(OH)2 compact made with 0.2-2.0 MPa and their carbonation at 200-800ºC for 1 h. Microporous <span class="hlt">calcite</span> was obtained only when carbonated at 600ºC using Ca(OH)2 compact made with 0.2 MPa even though thermogravimetry analysis showed that <span class="hlt">calcite</span> powder was stable up to 920ºC under CO2 atmosphere. CaO formed by carbonation at 700ºC and 800ºC is thought to be caused by the limited CO2 diffusion interior to the Ca(OH)2 compact. Also, unreacted Ca(OH)2 was found for Ca(OH)2 compact prepared with 0.5 MPa or higher pressure even when carbonated at 600ºC. As a result of high temperature carbonation, crystallite size of the <span class="hlt">calcite</span>, 58.0 nm, was significantly larger when compared to that of <span class="hlt">calcite</span> prepared at room temperature, 35.5 nm. Porosity and diametral tensile strength of the microporous <span class="hlt">calcite</span> were 39.5% and 6.4 MPa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1038168','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1038168"><span>Mixing-induced <span class="hlt">calcite</span> precipitation and dissolution kinetics in micromodel experiments.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Valocchi, Albert J.; Dewers, Thomas A.; Dehoff, Karl; Yoon, Hongkyu; Werth, Charles J.</p> <p>2010-12-01</p> <p>Dissolved CO2 from geological CO2 sequestration may react with dissolved minerals in fractured rocks or confined aquifers and cause mineral precipitation. The overall rate of reaction can be limited by diffusive or dispersive mixing, and mineral precipitation can block pores and further hinder these processes. Mixing-induced <span class="hlt">calcite</span> precipitation experiments were performed by injecting solutions containing CaCl2 and Na2CO3 through two separate inlets of a micromodel (1-cm x 2-cm x 40-microns); transverse dispersion caused the two solutions to mix along the center of the micromodel, resulting in <span class="hlt">calcite</span> precipitation. The amount of <span class="hlt">calcite</span> precipitation initially increased to a maximum and then decreased to a steady state value. Fluorescent microscopy and imaging techniques were used to visualize <span class="hlt">calcite</span> precipitation, and the corresponding effects on the flow field. Experimental micromodel results were evaluated with pore-scale simulations using a 2-D Lattice-Boltzmann code for water flow and a finite volume code for reactive transport. The reactive transport model included the impact of pH upon carbonate speciation and <span class="hlt">calcite</span> dissolution. We found that proper estimation of the effective diffusion coefficient and the reaction surface area is necessary to adequately simulate precipitation and dissolution rates. The effective diffusion coefficient was decreased in grid cells where <span class="hlt">calcite</span> precipitated, and keeping track of reactive surface over time played a significant role in predicting reaction patterns. Our results may improve understanding of the fundamental physicochemical processes during CO2 sequestration in geologic formations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21366844','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21366844"><span>INDEX OF REFRACTION OF SHOCK LOADED SODA-<span class="hlt">LIME</span> GLASS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Alexander, C. S.</p> <p>2009-12-28</p> <p>Soda-<span class="hlt">lime</span> glass (SLG) is a potential low-cost VISAR window for use at moderate shock pressures (up to 2430 GPa) where the material remains transparent. In order for SLG to be practical as a VISAR window, the correction factor, which describes the frequency correction related to the strain dependence of the refractive index, and hence the index of refraction itself, must be characterized as a function of pressure. Characterization data are reported in this paper and compared to previous results. The present data show good agreement with those of Dandekar [J. Appl. Phys. 84, 6614 (1998)] and separate study results by Gibbons and Ahrens [J. Geophys. Res. 76, 5489 (1971)] up to 7 GPa. However, at stresses over 7 GPa, marked discrepancies are evident between the present data and that of Gibbons and Ahrens. Differences in test methods may explain these discrepancies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12382772','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12382772"><span>Luminescence quartz dating of <span class="hlt">lime</span> mortars. A first research approach.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zacharias, N; Mauz, B; Michael, C T</p> <p>2002-01-01</p> <p><span class="hlt">Lime</span> mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870 +/- 230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095 +/- 190 a.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998AIPC..429..521C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998AIPC..429..521C"><span>Effect of shear on failure waves in soda <span class="hlt">lime</span> glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clifton, R. J.; Mello, M.; Brar, N. S.</p> <p>1998-07-01</p> <p>By means of in-material stress gauges, failure waves in shock-compressed soda <span class="hlt">lime</span> glass have been shown to be distinguished by a marked reduction in shear stress. To explore further the relation between failure waves and shearing resistance, a series of pressure-shear impact experiments have been performed involving the impact of a glass plate by a steel flyer plate and vice versa. The latter configuration is designed to allow direct measurements of the shearing resistance of the failed material. In both configurations, the normal and transverse motion of the free surface of the target is monitored using laser interferometry. The transverse velocity-time profiles show a pronounced loss in shearing resistance of the glass at impact velocities above the threshold for failure waves to occur.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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