Mineral Deposition in Bacteria-Filled and Bacteria-Free Calcium Bodies in the Crustacean Hyloniscus riparius (Isopoda: Oniscidea)

PubMed Central

Vittori, Miloš; Rozman, Alenka; Grdadolnik, Jože; Novak, Urban; Štrus, Jasna

2013-01-01

Crustacean calcium bodies are epithelial sacs which contain a mineralized matrix. The objectives of this study were to describe the microscopic anatomy of calcium bodies in the terrestrial isopod Hyloniscus riparius and to establish whether they undergo molt-related structural changes. We performed 3D reconstruction of the calcium bodies from paraffin sections and analyzed their structure with light and electron microscopy. In addition, we analyzed the chemical composition of their mineralized matrices with micro-Raman spectroscopy. Two pairs of these organs are present in H. riparius. One pair is filled with bacteria while the other pair is not. In non-molting animals, the bacteria-filled calcium bodies contain apatite crystals and the bacteria-free calcium bodies enclose CaCO3-containing concretions with little organic matrix. During preparation for molt, an additional matrix layer is deposited in both pairs of calcium bodies. In the bacteria-filled calcium bodies it contains a mixture of calcium carbonate and calcium phosphate, whereas only calcium carbonate is present in bacteria-free calcium bodies. After ecdysis, all mineral components in bacteria-free calcium bodies and the additional matrix layer in bacteria-filled calcium bodies are completely resorbed. During calcium resorption, the apical surface of the calcium body epithelium is deeply folded and electron dense granules are present in spaces between epithelial cells. Our results indicate that the presence of bacteria might be linked to calcium phosphate mineralization. Calcium bodies likely provide a source of calcium and potentially phosphate for the mineralization of the new cuticle after molt. Unlike other terrestrial isopods, H. riparius does not form sternal CaCO3 deposits and the bacteria-free calcium bodies might functionally replace them in this species. PMID:23554963

Layer-by-Layer Assembled Nanotubes as Biomimetic Nanoreactors for Calcium Carbonate Deposition.

PubMed

He, Qiang; Möhwald, Helmuth; Li, Junbai

2009-09-17

Enzyme-loaded magnetic polyelectrolyte multilayer nanotubes prepared by layer-by-layer assembly combined with the porous template could be used as biomimetic nanoreactors. It is demonstrated that calcium carbonate can be biomimetically synthesized inside the cavities of the polyelectrolyte nanotubes by the catalysis of urease, and the size of the calcium carbonate precipitates was controlled by the cavity dimensions. The metastable structure of the calcium carbonate precipitates inside the nanotubes was protected by the outer shell of the polyelectrolyte multilayers. These features may allow polyelectrolyte nanotubes to be applied in the fields of nanomaterials synthesis, controlled release, and drug delivery. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization of elemental and structural composition of corrosion scales and deposits formed in drinking water distribution systems.

PubMed

Peng, Ching-Yu; Korshin, Gregory V; Valentine, Richard L; Hill, Andrew S; Friedman, Melinda J; Reiber, Steve H

2010-08-01

Corrosion scales and deposits formed within drinking water distribution systems (DWDSs) have the potential to retain inorganic contaminants. The objective of this study was to characterize the elemental and structural composition of extracted pipe solids and hydraulically-mobile deposits originating from representative DWDSs. Goethite (alpha-FeOOH), magnetite (Fe(3)O(4)) and siderite (FeCO(3)) were the primary crystalline phases identified in most of the selected samples. Among the major constituent elements of the deposits, iron was most prevalent followed, in the order of decreasing prevalence, by sulfur, organic carbon, calcium, inorganic carbon, phosphorus, manganese, magnesium, aluminum and zinc. The cumulative occurrence profiles of iron, sulfur, calcium and phosphorus for pipe specimens and flushed solids were similar. Comparison of relative occurrences of these elements indicates that hydraulic disturbances may have relatively less impact on the release of manganese, aluminum and zinc, but more impact on the release of organic carbon, inorganic carbon, and magnesium. (c) 2010 Elsevier Ltd. All rights reserved.

Oral calcium carbonate affects calcium but not phosphorus balance in stage 3-4 chronic kidney disease.

PubMed

Hill, Kathleen M; Martin, Berdine R; Wastney, Meryl E; McCabe, George P; Moe, Sharon M; Weaver, Connie M; Peacock, Munro

2013-05-01

Patients with chronic kidney disease (CKD) are given calcium carbonate to bind dietary phosphorus, reduce phosphorus retention, and prevent negative calcium balance; however, data are limited on calcium and phosphorus balance during CKD to support this. Here, we studied eight patients with stage 3 or 4 CKD (mean estimated glomerular filtration rate 36 ml/min) who received a controlled diet with or without a calcium carbonate supplement (1500 mg/day calcium) during two 3-week balance periods in a randomized placebo-controlled cross-over design. All feces and urine were collected during weeks 2 and 3 of each balance period and fasting blood, and urine was collected at baseline and at the end of each week. Calcium kinetics were determined using oral and intravenous (45)calcium. Patients were found to be in neutral calcium and phosphorus balance while on the placebo. Calcium carbonate supplementation produced positive calcium balance, did not affect phosphorus balance, and produced only a modest reduction in urine phosphorus excretion compared with placebo. Calcium kinetics demonstrated positive net bone balance but less than overall calcium balance, suggesting soft-tissue deposition. Fasting blood and urine biochemistries of calcium and phosphate homeostasis were unaffected by calcium carbonate. Thus, the positive calcium balance produced by calcium carbonate treatment within 3 weeks cautions against its use as a phosphate binder in patients with stage 3 or 4 CKD, if these findings can be extrapolated to long-term therapy.

Return of the coral reef hypothesis: basin to shelf partitioning of CaCO3 and its effect on atmospheric CO2.

PubMed

Opdyke, B N; Walker, J C

1992-08-01

Differences in the rate of coral reef carbonate deposition from the Pleistocene to the Holocene may account for the Quaternary variation of atmospheric CO2. Volumes of carbonate associated with Holocene reefs require an average deposition rate of 2.0 x 10(13) mol/yr for the past 5 ka. In light of combined riverine, midocean ridge, and ground-water fluxes of calcium to the oceans of 2.3 x 10(13) mol/yr, the current flux of calcium carbonate to pelagic sediments must be far below the Pleistocene average of 1.2 x 10(13) mol/yr. We suggest that sea-level change shifts the locus of carbonate deposition from the deep sea to the shelves as the normal glacial-interglacial pattern of deposition for Quaternary global carbonates. To assess the impact of these changes on atmospheric CO2, a simple numerical simulation of the global carbon cycle was developed. Atmospheric CO2 as well as calcite saturation depth and sediment responses to these carbonate deposition changes are examined. Atmospheric CO2 changes close to those observed in the Vostok ice core, approximately 80 ppm CO2, for the Quaternary are observed as well as the approximate depth changes in percent carbonate of sediments measured in the Pacific Ocean over the same time interval.

Amorphous calcium carbonate controls avian eggshell mineralization: A new paradigm for understanding rapid eggshell calcification.

PubMed

Rodríguez-Navarro, Alejandro B; Marie, Pauline; Nys, Yves; Hincke, Maxwell T; Gautron, Joel

2015-06-01

Avian eggshell mineralization is the fastest biogenic calcification process known in nature. How this is achieved while producing a highly crystalline material composed of large calcite columnar single crystals remains largely unknown. Here we report that eggshell mineral originates from the accumulation of flat disk-shaped amorphous calcium carbonate (ACC) particles on specific organic sites on the eggshell membrane, which are rich in proteins and sulfated proteoglycans. These structures known as mammillary cores promote the nucleation and stabilization of a amorphous calcium carbonate with calcitic short range order which predetermine the calcite composition of the mature eggshell. The amorphous nature of the precursor phase was confirmed by the diffuse scattering of X-rays and electrons. The nascent calcitic short-range order of this transient mineral phase was revealed by infrared spectroscopy and HRTEM. The ACC mineral deposited around the mammillary core sites progressively transforms directly into calcite crystals without the occurrence of any intermediate phase. Ionic speciation data suggest that the uterine fluid is equilibrated with amorphous calcium carbonate, throughout the duration of eggshell mineralization process, supporting that this mineral phase is constantly forming at the shell mineralization front. On the other hand, the transient amorphous calcium carbonate mineral deposits, as well as the calcite crystals into which they are converted, form by the ordered aggregation of nanoparticles that support the rapid mineralization of the eggshell. The results of this study alter our current understanding of avian eggshell calcification and provide new insights into the genesis and formation of calcium carbonate biominerals in vertebrates. Copyright © 2015 Elsevier Inc. All rights reserved.

Sea urchin spine calcite forms via a transient amorphous calcium carbonate phase.

PubMed

Politi, Yael; Arad, Talmon; Klein, Eugenia; Weiner, Steve; Addadi, Lia

2004-11-12

The skeletons of adult echinoderms comprise large single crystals of calcite with smooth convoluted fenestrated morphologies, raising many questions about how they form. By using water etching, infrared spectroscopy, electron diffraction, and environmental scanning electron microscopy, we show that sea urchin spine regeneration proceeds via the initial deposition of amorphous calcium carbonate. Because most echinoderms produce the same type of skeletal material, they probably all use this same mechanism. Deposition of transient amorphous phases as a strategy for producing single crystals with complex morphology may have interesting implications for the development of sophisticated materials.

Mineralogical influences on porosity-depth trends of shelf deposits (Miocene-Pleistocene) along the northwest shelf of Australia (IODP Expedition 356)

NASA Astrophysics Data System (ADS)

Knierzinger, Wolfgang; Lee, Eun Young; Wagreich, Michael

2017-04-01

Porosity in sediments is influenced by various factors such as mineralogical composition, burial depth, connate fluids, and stratigraphic layering. This work focuses on processes underlying porosity anomalies in carbonate shelf deposits along the northwest shelf of Australia by using different techniques (polarization microscopy, electron microscopy, XRD, XRF). IODP expedition 356 recovered cored seven sites (U1458-U1464), covering a latitudinal range of 29°S-18°S on the northwest shelf. Strong negative deviations from general porosity-depth trends for these carbonate rich sediments are clear for samples with higher contents of dolomite, calcium sulfates, and non-skeletal calcite. No significant influence of aragonite on porosity values has yet been detected. However, it is likely that the occurrence of high amounts of aragonite is a crucial element with regard to porosity values in these carbonate rich deposits, since elongated aragonite needles commonly enhance interparticle porosity. Further insight might be gained through the application of electron microscopy. In general, sediments in the northern part of the study area (Sites U1462, U1463, U1464) tend to show slightly higher porosity values compared to sediments form the south (Sites U1459, U1460). This may reflect the influence of calcium sulfate, because mineralogical analyses show, calcium sulfate is relatively rare at the southern sites, whereas higher amounts of calcium sulfates occur in the north. The lack of detrital particles in calcium sulfate components indicates an evaporitic origin. Deposits at Site U 1461 differ from other analyzed sediments insofar as higher amounts of feldspars and micas are apparent. *This research is conducted within the frame of the 'International Ocean Discovery Program', funded by the Ministry of Oceans and Fisheries, Korea.

Role of calcium-depositing bacteria Agrobacterium tumefaciens and its influence on corrosion of different engineering metals used in cooling water system.

PubMed

Narenkumar, Jayaraman; Sathishkumar, Kuppusamy; Selvi, Adikesavan; Gobinath, Rajagopalan; Murugan, Kadarkarai; Rajasekar, Aruliah

2017-12-01

The present investigation deals with the role of calcium-depositing bacterial community on corrosion of various engineering metals, namely, brass alloy (BS), copper (Cu), stainless steel (SS) and mild steel (MS). Based on the corrosion behavior, Agrobacterium tumefaciens EN13, an aerobic bacterium is identified as calcium-depositing bacteria on engineering metals. The results of the study are supported with biochemical characterization, 16S rRNA gene sequencing, calcium quantification, weight loss, electrochemical (impedance and polarization) and surface analysis (XRD and FTIR) studies. The calcium quantification study showed carbonate precipitation in abiotic system/biotic system as 50 and 700 ppm, respectively. FTIR results too confirmed the accumulation of calcium deposits from the environment on the metal surface by EN13. Electrochemical studies too supported the corrosion mechanism by showing a significant increase in the charge transfer resistance ( R ct ) of abiotic system (44, 33.6, 45, 29.6 Ω cm 2 ) than compared to biotic system (41, 10.1 29 and 25 Ω cm 2 ). Hence, the outcome of the present study confirmed the enhanced bioaccumulation behavior of calcium by the strain, EN13.

Electromigration and Deposition of Micro-Scale Calcium Carbonate Structures with Controlled Morphology and Polymorphism

DTIC Science & Technology

2013-04-01

precipitation of calcium carbonate in structured templates including microporous polycarbonate membranes and polyethylene foams. Para- meters...polyethylene foam). Microporous polycarbonate membranes and Medium-Density PolyEthylene (MDPE) foam specimens were used as the porous organic...voids in hardened concrete. DOI:10.1520/C624-06. West Conshohocken, PA: ASTM International . www.astm.org. Bersa, L., and M. Liu. 2007. A review on

Calcium phosphate mineralization is widely applied in crustacean mandibles.

PubMed

Bentov, Shmuel; Aflalo, Eliahu D; Tynyakov, Jenny; Glazer, Lilah; Sagi, Amir

2016-02-24

Crustaceans, like most mineralized invertebrates, adopted calcium carbonate mineralization for bulk skeleton reinforcement. Here, we show that a major part of the crustacean class Malacostraca (which includes lobsters, crayfishes, prawns and shrimps) shifted toward the formation of calcium phosphate as the main mineral at specified locations of the mandibular teeth. In these structures, calcium phosphate is not merely co-precipitated with the bulk calcium carbonate but rather creates specialized structures in which a layer of calcium phosphate, frequently in the form of crystalline fluorapatite, is mounted over a calcareous "jaw". From a functional perspective, the co-existence of carbonate and phosphate mineralization demonstrates a biomineralization system that provides a versatile route to control the physico-chemical properties of skeletal elements. This system enables the deposition of amorphous calcium carbonate, amorphous calcium phosphate, calcite and apatite at various skeletal locations, as well as combinations of these minerals, to form graded composites materials. This study demonstrates the widespread occurrence of the dual mineralization strategy in the Malacostraca, suggesting that in terms of evolution, this feature of phosphatic teeth did not evolve independently in the different groups but rather represents an early common trait.

Calcium phosphate mineralization is widely applied in crustacean mandibles

PubMed Central

Bentov, Shmuel; Aflalo, Eliahu D.; Tynyakov, Jenny; Glazer, Lilah; Sagi, Amir

2016-01-01

Crustaceans, like most mineralized invertebrates, adopted calcium carbonate mineralization for bulk skeleton reinforcement. Here, we show that a major part of the crustacean class Malacostraca (which includes lobsters, crayfishes, prawns and shrimps) shifted toward the formation of calcium phosphate as the main mineral at specified locations of the mandibular teeth. In these structures, calcium phosphate is not merely co-precipitated with the bulk calcium carbonate but rather creates specialized structures in which a layer of calcium phosphate, frequently in the form of crystalline fluorapatite, is mounted over a calcareous “jaw”. From a functional perspective, the co-existence of carbonate and phosphate mineralization demonstrates a biomineralization system that provides a versatile route to control the physico-chemical properties of skeletal elements. This system enables the deposition of amorphous calcium carbonate, amorphous calcium phosphate, calcite and apatite at various skeletal locations, as well as combinations of these minerals, to form graded composites materials. This study demonstrates the widespread occurrence of the dual mineralization strategy in the Malacostraca, suggesting that in terms of evolution, this feature of phosphatic teeth did not evolve independently in the different groups but rather represents an early common trait. PMID:26906263

Effects of acid deposition on dissolution of carbonate stone during summer storms in the Adirondack Mountains, New York, 1987-89

USGS Publications Warehouse

Schuster, Paul F.; Reddy, Michael M.; Sherwood, S.I.

1994-01-01

This study is part of a long-term research program designed to identify and quantify acid rain damage to carbonate stone. Acidic deposition accelerates the dissolution of carbonate-stone monuments and building materials. Sequential sampling of runoff from carbonate-stone (marble) and glass (reference) microcatchments in the Adirondack Mountains in New York State provided a detailed record of the episodic fluctuations in rain rate and runoff chemistry during individual summer storms. Rain rate and chemical concentrations from carbonate-stone and glass runoff fluctuated three to tenfold during storms. Net calcium-ion concentrations from the carbonatestone runoff, a measure of stone dissolution, typically fluctuated twofold during these storms. High net sulfate and net calcium concentrations in the first effective runoff at the start of a storm indicated that atmospheric pollutants deposited on the stone surface during dry periods formed calcium sulfate minerals, an important process in carbonate stone dissolution. Dissolution of the carbonate stone generally increased up to twofold during coincident episodes of low rain rate (less than 5 millimeters per hour) and decreased rainfall (glass runoff) pH (less than 4.0); episodes of high rain rate (cloudbursts) were coincident with a rapid increase in rainfall pH and also a rapid decrease in the dissolution of carbonate-stone. During a storm, it seems the most important factors causing increased dissolution of carbonate stone are coincident periods of low rain rate and decreased rainfall pH. Dissolution of the carbonate stone decreased slightly as the rain rate exceeded about 5 millimeters per hour, probably in response to rapidly increasing rainfall pH during episodes of high rain rate and shorter contact time between the runoff and the stone surface. High runoff rates resulting from cloudbursts remove calcium sulfate minerals formed during dry periods prior to storms and also remove dissolution products formed in large measure by chemical weathering as a result of episodes of low rain rate and decreased rainfall pH during a storm.

Geology and Thermal History of Mammoth Hot Springs, Yellowstone National Park, Wyoming

USGS Publications Warehouse

Bargar, Keith E.

1978-01-01

Mammoth Hot Springs, located about 8 km inside the north entrance to Yellowstone National Park, consists of nearly 100 hot springs scattered over a score of steplike travertine terraces. The travertine deposits range in age from late Pleistocene to the present. Sporadic records of hot-spring activity suggest that most of the current major springs have been intermittently active since at least 1871. Water moving along the Norris-Mammoth fault zone is heated by partly molten magma and enriched in calcium and bicarbonate. Upon reaching Mammoth this thermal water (temperature about 73?C) moves up through the old terrace deposits along preexisting vertical linear planes of weakness. As the water reaches the surface, pressure is released, carbon dioxide escapes as a gas, and bicarbonate in the water is partitioned into more carbon dioxide and carbonate; the carbonate then combines with calcium to precipitate calcium carbonate, forming travertine. The travertine usually precipitates rapidly from solution and is lightweight and porous; however, dense travertine, such as is found in core from the 113-m research drill hole Y-10 located on one of the upper terraces, forms beneath the surface by deposition in the pore spaces of older deposits. The terraces abound with unusual hot-spring deposits such as terracettes, cones, and fissure ridges. Semicircular ledges (ranging in width from about 0.3 m to as much as 2.5 m), called terracettes, formed by deposition of travertine around slowly rising pools. Complex steplike arrangements of terracettes have developed along runoff channels of some hot springs. A few hot springs have deposited cone-shaped mounds, most of which reach heights of 1-2 m before becoming dormant. However, one long-inactive cone named Liberty Cap attained a height of about 14 m. Fissure ridges are linear mounds of travertine deposited from numerous hot-spring vents along a medial fracture zone. The ridges range in height from about 1 to 6 m and in length from a few meters to nearly 300 m; width at the base of a ridge is equal to or greater than its height. In some places, such as along the northern border of Main Terrace, water from new hot-spring activity becomes ponded behind fissure-ridge barriers or dams and deposits travertine that eventually forms large flat terraces.

Strangelove Ocean and Deposition of Unusual Shallow-Water Carbonates After the End-Permian Mass Extinction

NASA Technical Reports Server (NTRS)

Rampino, Michael R.; Caldeira, Ken

2003-01-01

The severe mass extinction of marine and terrestrial organisms at the end of the Permian Period (approx. 251 Ma) was accompanied by a rapid negative excursion of approx. 3 to 4 per mil in the carbon-isotope ratio of the global surface oceans and atmosphere that persisted for some 500,000 into the Early Triassic. Simulations with an ocean-atmosphere/carbon-cycle model suggest that the isotope excursion can be explained by collapse of ocean primary productivity (a Strangelove Ocean) and changes in the delivery and cycling of carbon in the ocean and on land. Model results also suggest that perturbations of the global carbon cycle resulting from the extinctions led to short-term fluctuations in atmospheric pCO2 and ocean carbonate deposition, and to a long-term (>1 Ma) decrease in sedimentary burial of organic carbon in the Triassic. Deposition of calcium carbonate is a major sink of river-derived ocean alkalinity and for CO2 from the ocean/atmosphere system. The end of the Permian was marked by extinction of most calcium carbonate secreting organisms. Therefore, the reduction of carbonate accumulation made the oceans vulnerable to a build-up of alkalinity and related fluctuations in atmospheric CO2. Our model results suggest that an increase in ocean carbonate-ion concentration should cause increased carbonate accumulation rates in shallow-water settings. After the end-Permian extinctions, early Triassic shallow-water sediments show an abundance of abiogenic and microbial carbonates that removed CaCO3 from the ocean and may have prevented a full 'ocean-alkalinity crisis' from developing.

Microorganisms in the deposits of cold carbon mineral waters of the Russian Far East and their habitats

NASA Astrophysics Data System (ADS)

Kalitina, E. G.; Kharitonova, N. A.; Kuzmina, T. V.; Chelnokov, G. A.

2018-01-01

Study of the chemical composition of carbon mineral waters has shown the prevalence of calcium, magnesium and sodium among the cations, sulfate, nitrate and chloride ions among the anions, and ferric iron, strontium and manganese in the microelement composition. Results of the microbiological studies have revealed that carbon mineral waters contain various microorganisms that can transform the physical and chemical composition of mineral waters by interfering with geochemical cycles. The sanitary and microbiological properties of carbon mineral waters have been evaluated thus proving that the waters of Medvezhii (Shmakovskoe deposit) are microbiologically clean.

Development of poly(aspartic acid-co-malic acid) composites for calcium carbonate and sulphate scale inhibition.

PubMed

Mithil Kumar, N; Gupta, Sanjay Kumar; Jagadeesh, Dani; Kanny, K; Bux, F

2015-01-01

Polyaspartic acid (PSI) is suitable for the inhibition of inorganic scale deposition. To enhance its scale inhibition efficiency, PSI was modified by reacting aspartic acid with malic acid (MA) using thermal polycondensation polymerization. This reaction resulted in poly(aspartic acid-co-malic acid) (PSI-co-MA) dual polymer. The structural, chemical and thermal properties of the dual polymers were analysed by using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and gel permeation chromatography. The effectiveness of six different molar ratios of PSI-co-MA dual polymer for calcium carbonate and calcium sulphate scale inhibition at laboratory scale batch experiments was evaluated with synthetic brine solution at selected doses of polymer at 65-70°C by the static scale test method. The performance of PSI-co-MA dual polymer for the inhibition of calcium carbonate and calcium sulphate precipitation was compared with that of a PSI single polymer. The PSI-co-MA exhibited excellent ability to control inorganic minerals, with approximately 85.36% calcium carbonate inhibition and 100% calcium sulphate inhibition at a level of 10 mg/L PSI-co-MA, respectively. Therefore, it may be reasonably concluded that PSI-co-MA is a highly effective scale inhibitor for cooling water treatment applications.

Carbonic anhydrase activity in developing sea urchin embryos with special reference to calcification of spicules.

PubMed

Mitsunaga, K; Akasaka, K; Shimada, H; Fujino, Y; Yasumasu, I; Numanoi, H

1986-06-01

Eggs and embryos of the sea urchins Anthocidaris crassispina and Hemicentrotus pulcherrimus did not exhibit significant changes in carbonic anhydrase activity during early development. Acetazolamide inhibited enzyme activity in homogenates of embryos and inhibited the formation of calcified spicules in a culture of micromeres at concentrations between 40 and 100 microM. Acetazolamide allowed intact embryos to develop to quasi-normal plutei but inhibited calcium deposition in the spicules. It is suggested that carbonic anhydrase contributes to CaCO3 deposition in the spicule.

Biogenic Fish-gut Calcium Carbonate is a Stable Amorphous Phase in the Gilt-head Seabream, Sparus aurata

PubMed Central

Foran, Elizabeth; Weiner, Steve; Fine, Maoz

2013-01-01

The main source of calcium carbonate (CaCO3) in the ocean comes from the shells of calcifying planktonic organisms, but substantial amounts of CaCO3 are also produced in fish intestines. The precipitation of CaCO3 assists fish in intestinal water absorption and aids in whole body Ca2+ homeostasis. Here we report that the product formed in the intestinal lumen of the gilt-head seabream, Sparus aurata, is an amorphous calcium carbonate (ACC) phase. With FTIR spectroscopy and SEM imaging, our study shows that the fish-derived carbonates from S. aurata are maintained as a stable amorphous phase throughout the intestinal tract. Moreover, intestinal deposits contained up to 54 mol% Mg2+, the highest concentration yet reported in biogenic ACC. Mg is most likely responsible for stabilizing this inherently unstable mineral. The fish carbonates also displayed initial rapid dissolution when exposed to seawater, exhibiting a significant increase in carbonate concentration. PMID:23609008

Detectability of Martian carbonates from orbit using thermal neutrons

NASA Technical Reports Server (NTRS)

Feldman, W. C.; Jakosky, B. M.

1991-01-01

Numerical simulations of Martian neutron leakage flux spectra are made in order to explore the detectability of magnesium and calcium carbonate deposits using neutron spectroscopic techniques from orbit. The primary signature of such deposits is found to be an enhanced thermal amplitude. Although this enhancement is weakened by: (1) partial burial beneath an aeolian regolith blanket; (2) admixture with regolith on a microscopic (centimeter) or macroscopic (tens of centimeters) scale; and (3) reduction in the areal size of the deposit, near-surface stratigraphies of carbonates hypothesized by some authors as possible on Mars are still detectable by simple neutron sensors from orbit. However, the large variations in the magnitude of the thermal neutron enhancements caused by different carbonate deposit configurations found in this study require a combined gamma ray and neutron analysis for their unique specification.

Subglacial carbonate precipitates on central Baffin Island, Arctic Canada may constrain basal conditions for the Foxe sector of the Laurentide Ice Sheet

NASA Astrophysics Data System (ADS)

Miller, G. H.; Refsnider, K. A.

2009-12-01

Extensive, widespread carbonate deposits on gneissic bedrock have recently been discovered around the Barnes Ice Cap, central Baffin Island. Deposits range from conglomeratic crack-fillings ≤5 cm thick to laminated, striated films plastered on bedrock surfaces, often in the lee of obstacles. A single outcrop of these carbonates was first described by Andrews et al. (1972, Canadian Journal of Earth Sciences, 9, 233-238) and was interpreted as an early Tertiary limestone based on the presence of warm-climate palynomorphs including Liriodendron (tulip tree), Ulmus (elm), and Taxodium (cypress). However, recent fieldwork in the region has demonstrated that these carbonates are far more ubiquitous than previously thought and found on both glacially-polished bedrock surfaces and till boulders that melted out in recent decades from Laurentide ice at the base of the Barnes Ice Cap. In many cases, these carbonates exhibit the characteristic morphologies of subglacial carbonates (flutes, furrows, and striations parallel to the direction of ice flow, columnar spicules, and tufa-dam-like forms). A few deposits include angular sands, gravels, and pebbles. The nearest carbonate bedrock is Paleozoic limestone flooring Foxe Basin 130 km west of the Barnes Ice Cap summit. While subglacial carbonate deposits have been documented adjacent to retreating mountain and outlet glaciers and in areas previously covered by Pleistocene ice sheets, few localities are distant from carbonate bedrock. Thus, the carbon required for carbonate deposition in the Barnes region was either (1) derived from Paleozoic limestone and dissolved in subglacial water that was subject to long-distance transport, or (2) there was sufficient trapped atmospheric CO2 in the ice to yield alkaline basal meltwater which hydrolyzed calcium-bearing silicates in the local bedrock. Given the volume of carbonate deposited at some sites, we find the latter model unlikely. If the former model is applicable, these carbonates will provide considerable insight into subglacial processes beneath the Foxe sector of the Laurentide Ice Sheet and possibly constrain the former ice thicknesses above these sites. Quantitative x-ray diffraction defines the mineralogy of both the carbonate and clastic components. Carbon and strontium isotopes in the carbonate precipitates, Foxe Basin Paleozoic bedrock, and local bedrock should define the source of the carbon and calcium in the deposits. Oxygen isotopes of Barnes Ice Cap Laurentide ice and the carbonates provide a unique opportunity to compare the isotopic composition of subglacial carbonates with the isotopic composition of the actual ice sheet under which they were precipitated.

Sediment transport by fishes in Harrington Sound, Bermuda

NASA Astrophysics Data System (ADS)

Alheit, Jürgen

1983-11-01

Harrington Sound, Bermuda, is a shallow subtropical lagoon with carbonate sediments. The most important fishes in this lagoon, in terms of biomass, are grunts (Haemulon aurolineatum, H. flavolineatum, H. sciurus) and a sea-bream (Diplodus bermudensis). These undertake diel feeding migrations from the shallow rocky zone towards the deeper sand and mud zones. When feeding on zoobenthos they cannot avoid swallowing carbonate sediment particles. These sediment particles pass through the alimentary canal of the fishes and are deposited again, after digestion of the food, as faeces in the shallow zones. Thus, the fishes transport the sediment in an unusual direction, from the deep to the shallow zones, in effect against the force of gravity. By recording the fish stock densities, digestion rates, and calcium carbonate content of fish stomach and guts, it was possible to estimate the amount of sediment transported by the fishes. In Harrington Sound, this amounts annually to 4530 kg calcium carbonate, 40% of which is deposited in the very shallow areas. The pH-values measured in fish stomachs seem to be acidic enough for the dissolution of carbonate sediment particles when transported by fishes.

Climatically driven loss of calcium in steppe soil as a sink for atmospheric carbon

USGS Publications Warehouse

Lapenis, A.G.; Lawrence, G.B.; Bailey, S.W.; Aparin, B.F.; Shiklomanov, A.I.; Speranskaya, N.A.; Torn, M.S.; Calef, M.

2008-01-01

During the last several thousand years the semi-arid, cold climate of the Russian steppe formed highly fertile soils rich in organic carbon and calcium (classified as Chernozems in the Russian system). Analysis of archived soil samples collected in Kemannaya Steppe Preserve in 1920, 1947, 1970, and fresh samples collected in 1998 indicated that the native steppe Chernozems, however, lost 17-28 kg m-2 of calcium in the form of carbonates in 1970-1998. Here we demonstrate that the loss of calcium was caused by fundamental shift in the steppe hydrologic balance. Previously unleached soils where precipitation was less than potential evapotranspiration are now being leached due to increased precipitation and, possibly, due to decreased actual evapotranspiration. Because this region receives low levels of acidic deposition, the dissolution of carbonates involves the consumption of atmospheric CO2. Our estimates indicate that this climatically driven terrestrial sink of atmospheric CO2 is ???2.1-7.4 g C m-2 a-1. In addition to the net sink of atmospheric carbon, leaching of pedogenic carbonates significantly amplified seasonal amplitude of CO2 exchange between atmosphere and steppe soil. Copyright 2008 by the American Geophysical Union.

Biogenic concrete protection driven by the formate oxidation by Methylocystis parvus OBBP.

PubMed

Ganendra, Giovanni; Wang, Jianyun; Ramos, Jose A; Derluyn, Hannelore; Rahier, Hubert; Cnudde, Veerle; Ho, Adrian; Boon, Nico

2015-01-01

The effectiveness of Microbiologically Induced Carbonate Precipitation (MICP) from the formate oxidation by Methylocystis parvus OBBP as an alternative process for concrete protection was investigated. MICP was induced on Autoclaved Aerated Concrete (AAC), the model material, by immersing the material in 10(9) M. parvus cells mL(-1) containing 5 g L(-1) of calcium formate. A 2 days immersion of the material gave the maximum weight increase of the specimens (38 ± 19 mg) and this was likely due to the deposition of calcium carbonate, biomass, and unconverted calcium formate. The solid deposition mainly occurred in the micropores of the specimen, close to the outer surface. A significantly lower water absorption was observed in the bacterially treated specimens compared to the non-treated ones (up to 2.92 ± 0.91 kg m(-2)) and this could be attributed to the solid deposition. However, the sonication test demonstrated that the bacterial treatment did not give a consolidating effect to the material. Overall, compared to the currently employed urea hydrolysis process, the formate-based MICP by M. parvus offers a more environmentally friendly approach for the biotechnological application to protect concrete.

Biogenic concrete protection driven by the formate oxidation by Methylocystis parvus OBBP

PubMed Central

Ganendra, Giovanni; Wang, Jianyun; Ramos, Jose A.; Derluyn, Hannelore; Rahier, Hubert; Cnudde, Veerle; Ho, Adrian; Boon, Nico

2015-01-01

The effectiveness of Microbiologically Induced Carbonate Precipitation (MICP) from the formate oxidation by Methylocystis parvus OBBP as an alternative process for concrete protection was investigated. MICP was induced on Autoclaved Aerated Concrete (AAC), the model material, by immersing the material in 109 M. parvus cells mL−1 containing 5 g L−1 of calcium formate. A 2 days immersion of the material gave the maximum weight increase of the specimens (38 ± 19 mg) and this was likely due to the deposition of calcium carbonate, biomass, and unconverted calcium formate. The solid deposition mainly occurred in the micropores of the specimen, close to the outer surface. A significantly lower water absorption was observed in the bacterially treated specimens compared to the non-treated ones (up to 2.92 ± 0.91 kg m−2) and this could be attributed to the solid deposition. However, the sonication test demonstrated that the bacterial treatment did not give a consolidating effect to the material. Overall, compared to the currently employed urea hydrolysis process, the formate-based MICP by M. parvus offers a more environmentally friendly approach for the biotechnological application to protect concrete. PMID:26284061

Crystallization from Gels

NASA Astrophysics Data System (ADS)

Narayana Kalkura, S.; Natarajan, Subramanian

Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone constituents are described. In addition, tables of gel-grown organic and inorganic crystals are provided.

Effects of phosphates on shellfish and on calcium carbonate crystallization in vitro. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilbur, K.M.

1986-07-17

It has been known that inorganic phosphate inhibits the precipitation of calcium carbonate in artificial sea water. This work addresses the question of whether phosphate also affects the deposition of CaCO/sub 3/ in the exoskeletons of invertebrates. Tetrasodiumpyrophosphate and pentasodiumtripolyphosphate in concentrations of 15 ppM caused abnormality, mortality, and inhibition of shell deposition in trochophore larvae of the oyster Crassostrea. Inhibition of shell growth resulting from pollution at 15 ppM could be expected in Rangia with orthophosphate, tetrasodium pyrophosphate, and sodiumtripolyphosphate, in Helisoma with tetrasodium pyrophosphate, and pentasodium tripolyphosphate, and in larvae of Crassostea the relative inhibitory action of shellmore » growth was tetrasodiumpyrophosphate > sodiumtripolyphosphate > sodium orthophosphate greater than or equal to sodium hexametaphosphate. 4 refs.« less

Application of Multiple Regression and Design of Experiments for Modelling the Effect of Monoethylene Glycol in the Calcium Carbonate Scaling Process.

PubMed

Kartnaller, Vinicius; Venâncio, Fabrício; F do Rosário, Francisca; Cajaiba, João

2018-04-10

To avoid gas hydrate formation during oil and gas production, companies usually employ thermodynamic inhibitors consisting of hydroxyl compounds, such as monoethylene glycol (MEG). However, these inhibitors may cause other types of fouling during production such as inorganic salt deposits (scale). Calcium carbonate is one of the main scaling salts and is a great concern, especially for the new pre-salt wells being explored in Brazil. Hence, it is important to understand how using inhibitors to control gas hydrate formation may be interacting with the scale formation process. Multiple regression and design of experiments were used to mathematically model the calcium carbonate scaling process and its evolution in the presence of MEG. It was seen that MEG, although inducing the precipitation by increasing the supersaturation ratio, actually works as a scale inhibitor for calcium carbonate in concentrations over 40%. This effect was not due to changes in the viscosity, as suggested in the literature, but possibly to the binding of MEG to the CaCO₃ particles' surface. The interaction of the MEG inhibition effect with the system's variables was also assessed, when temperature' and calcium concentration were more relevant.

Insights into electrodeposition of an inhibitor film and its inhibitive effects on calcium carbonate deposition.

PubMed

Morizot, Arnaud P; Neville, Anne

2002-01-01

Polycarboxylic acid (PAA), a common scale inhibitor has demonstrated adsorption properties on stainless steel surfaces. An electrochemically based technique has been used to assess the extent of film formation. The presence of calcium and magnesium ions in the solution and the cathodic electrochemical activity at the metal surface have been shown to enhance the inhibitor film formation by promoting the transport of the inhibitor from the solution to the metal surface. The effect of the inhibitor film in retarding scale deposition is assessed using measurement of the deposition onto metal electrodes immersed in a supersaturated solution of CaCO(3). The practical implications of these findings are discussed.

Precipitation of calcium carbonate in aqueous solutions in presence of ethylene glycol and dodecane.

NASA Astrophysics Data System (ADS)

Natsi, Panagiota D.; Rokidi, Stamatia; Koutsoukos, Petros G.

2015-04-01

The formation of calcium carbonate (CaCO3) in aqueous supersaturated solutions has been intensively studied over the past decades, because of its significance for a number of processes of industrial and environmental interest. In the oil and gas production industry the deposition of calcium carbonate affects adversely the productivity of the wells. Calcium carbonate scale deposits formation causes serious problems in water desalination, CO2 sequestration in subsoil wells, in geothermal systems and in heat exchangers because of the low thermal coefficient of the salt. Amelioration of the operational conditions is possible only when the mechanisms underlying nucleation and crystal growth of calcium carbonate in the aqueous fluids is clarified. Given the fact that in oil production processes water miscible and immiscible hydrocarbons are present the changes of the dielectric constant of the fluid phase has serious impact in the kinetics of calcium carbonate precipitation, which remains largely unknown. The problem becomes even more complicated if polymorphism exhibited by calcium carbonate is also taken into consideration. In the present work, the stability of aqueous solutions supersaturated with respect to all calcium carbonate polymorphs and the subsequent kinetics of calcium carbonate precipitation were measured. The measurements included aqueous solutions and solutions in the presence of water miscible (ethylene glycol, MEG) and water immiscible organics (n-dodecane). All measurements were done at conditions of sustained supersaturation using the glass/ Ag/AgCl combination electrode as a probe of the precipitation and pH as the master variable for the addition of titrant solutions with appropriate concentration needed to maintenance the solution supersaturation. Initially, the metastable zone width was determined from measurements of the effect of the solution supersaturation on the induction time preceding the onset of precipitation at free-drift conditions. The rates of crystal growth were measured as a function of the solution supersaturation using the highly accurate and reproducible methodology of constant supersaturation. The dependence of the rates of crystal growth on supersaturation suggested surface diffusion controlled mechanism. At constant supersaturation it was possible to extend the time period for the growth of the initially forming polymorph, in a way that sufficient amount is precipitated for characterization with X-ray diffraction (XRD). Moreover, scanning electron microscopy (SEM) was used for the characterization of the morphology of the precipitated solid. In all cases and depending on the solution supersaturation vaterite formed first from solutions of high supersaturation while at low supersaturations calcite formed exclusively. The presence of dodecane reduced the stability of the supersaturated solutions with the crystals forming at the oil-water interface. The presence of ethylene glycol (concentrations between 10-80%) also affected the stability and the kinetics of calcium carbonate precipitation. The morphology of the formed crystals showed habit modifications: Spherical formations consisting of aggregated nanocrystals and calcite crystals with profound pits on the faces were the characteristic feature in the presence of dodecane. ACKNOWLEDGMENT This research was partially funded by the European Union (European Social Fund-ESF) and Greek National Funds through the Operational program Education and Lifelong Learning under the action Aristeia II( Code No 4420).

Properties of calcium silicate-monobasic calcium phosphate materials for endodontics containing tantalum pentoxide and zirconium oxide.

PubMed

Zamparini, Fausto; Siboni, Francesco; Prati, Carlo; Taddei, Paola; Gandolfi, Maria Giovanna

2018-05-08

The aim of the study was to evaluate chemical-physical properties and apatite-forming ability of three premixed calcium silicate materials containing monobasic calcium phosphate (CaH 4 P 2 O 8 ) bioceramic, tantalum pentoxide and zirconium oxide, recently marketed for endodontics (TotalFill BC-Sealer, BC-RRM-Paste, BC-RRM-Putty). Microchemical and micromorphological analyses, radiopacity, initial and final setting times, calcium release and alkalising activity were tested. The nucleation of calcium phosphates (CaPs) and/or apatite after 28 days ageing was evaluated by ESEM-EDX and micro-Raman spectroscopy. BC-Sealer and BC-RRM-Paste showed similar initial (23 h), prolonged final (52 h) setting times and good radiopacity (> 7 mm Al); BC-RRM-Putty showed fast initial (2 h) and final setting times (27 h) and excellent radiopacity (> 9 mm Al). All materials induced a marked alkalisation (pH 11-12) up to 28 days and showed the release of calcium ions throughout the entire test period (cumulative calcium release 641-806 ppm). After 28 days ageing, a well-distributed mineral layer was present on all samples surface; EDX demonstrated relevant calcium and phosphorous peaks. B-type carbonated apatite and calcite deposits were identified by micro-Raman spectroscopy on all the 28-day-aged samples; the deposit thickness was higher on BC-RRM-Paste and BC-RRM-Putty, in agreement with calcium release data. These materials met the required chemical and physical standards and released biologically relevant ions. The CaSi-CaH 4 P 2 O 8 system present in the materials provided Ca and OH ions release with marked abilities to nucleate a layer of B-type carbonated apatite favoured/accelerated by the bioceramic presence. The ability to nucleate apatite may lead many clinical advantages: In orthograde endodontics, it may improve the sealing ability by the deposition of CaPs at the material-root dentine interface, and in endodontic surgery, it could promote bone and periodontal tissue regeneration. As premixed materials, their application in endodontics may result easier in several complex endodontic situations (apicoectomy, root perforation, presence of wide/wet apices).

Novel Basic Protein, PfN23, Functions as Key Macromolecule during Nacre Formation*

PubMed Central

Fang, Dong; Pan, Cong; Lin, Huijuan; Lin, Ya; Zhang, Guiyou; Wang, Hongzhong; He, Maoxian; Xie, Liping; Zhang, Rongqing

2012-01-01

The fine microstructure of nacre (mother of pearl) illustrates the beauty of nature. Proteins found in nacre were believed to be “natural hands” that control nacre formation. In the classical view of nacre formation, nucleation of the main minerals, calcium carbonate, is induced on and by the acidic proteins in nacre. However, the basic proteins were not expected to be components of nacre. Here, we reported that a novel basic protein, PfN23, was a key accelerator in the control over crystal growth in nacre. The expression profile, in situ immunostaining, and in vitro immunodetection assays showed that PfN23 was localized within calcium carbonate crystals in the nacre. Knocking down the expression of PfN23 in adults via double-stranded RNA injection led to a disordered nacre surface in adults. Blocking the translation of PfN23 in embryos using morpholino oligomers led to the arrest of larval development. The in vitro crystallization assay showed that PfN23 increases the rate of calcium carbonate deposition and induced the formation of aragonite crystals with characteristics close to nacre. In addition, we constructed the peptides and truncations of different regions of this protein and found that the positively charged C-terminal region was a key region for the function of PfN23 Taken together, the basic protein PfN23 may be a key accelerator in the control of crystal growth in nacre. This provides a valuable balance to the classic view that acidic proteins control calcium carbonate deposition in nacre. PMID:22416139

The origin of high sodium bicarbonate waters in the Atlantic and Gulf Coastal Plains

USGS Publications Warehouse

Foster, M.D.

1950-01-01

Some sodium bicarbonate waters at depth in the Atlantic and Gulf Coastal Plains have the same bicarbonate content as the shallower calcium bicarbonate waters in the same formation and appear to be the result of replacement of calcium by sodium through the action of base-exchange minerals. Others, however, contain several hundred parts per million more of bicarbonate than any of the calcium bicarbonate waters and much more bicarbonate than can be attributed to solution of calcium carbonate through the action of carbon dioxide derived from the air and soil. As the waters in the Potomac group (Cretaceous) are all low in sulphate and as the environmental conditions under which the sediments of the Potomac group were deposited do not indicate that large amounts of sulphate are available for solution, it does not seem probable that carbon dioxide generated by chemical or biochemical breakdown of sulphate is responsible for the high sodium bicarbonate waters in this area. Sulphate as a source of oxygen is not necessary for the generation of carbon dioxide by carbonaceous material. Oxygen is an important constituent of carbonaceous material and carbon dioxide is a characteristic decomposition product of such material-as, for example, peat and lignite. Experimental work showed that distilled water, calcium bicarbonate water, and sodium bicarbonate water, after contact with lignite, calcium carbonate, and permutite (a base-exchange material), had all increased greatly in sodium bicarbonate content and had become similar in chemical character and in mineral content to high sodium bicarbonate waters found in the Coastal Plain. The tests indicated that carbonaceous material can act as a source of carbon dioxide, which, when dissolved in water, enables it to take into solution more calcium carbonate. If base-exchange materials are also present to replace calcium with sodium, a still greater amount of bicarbonate can be held in solution. The presence of carbonaceous material, together with calcium carbonate and base-exchange minerals in a formation is, therefore, sufficient to account for the occurrence in it of high sodium bicarbonate waters. ?? 1950.

Formation of cerussite and hydrocerussite during adsorption of lead from aqueous solution on oxidized carbons by cold oxygen plasma

NASA Astrophysics Data System (ADS)

De Velasco Maldonado, Paola S.; Hernández-Montoya, Virginia; Concheso, A.; Montes-Morán, Miguel A.

2016-11-01

A new procedure of elimination of Pb2+ from aqueous solution using carbon adsorbents, in which high amounts of cerussite and hydrocerussite are deposited on the carbon surfaces, is reported. The procedure includes the preparation of carbons from selected lignocellulosic wastes (pecan nut shells and peach stones) by single carbonization and further oxidation with cold oxygen plasma. The materials prior and after the oxidation treatment were characterized using elemental analysis, FT-IR spectroscopy, SEM/EDX analysis, adsorption of N2 at -196 °C and X-ray photoelectron spectroscopy. The adsorption of Pb2+ was carried out in batch systems under constant agitation. The formation of cerussite and hydrocerussite on the spent carbon surfaces was confirmed by XRD, SEM/EDX and FT-IR. A Pb2+ removal mechanism is proposed in which a co-precipitation of lead nitrate and calcium carbonate would render the formation of the lead carbonates. In such mechanism, the occurrence of CaCO3 on the surface of the adsorbents plays a crucial role. The presence of calcium carbonate on the precursors is understood on the basis of the thermal evolution of calcium oxalate originally present in the biomass. The oxygen plasma treatment helps to expose the calcium carbonate nanocrystals thus improving dramatically the removal capacity of Pb2+. Accordingly, retention capacities as high as 63 mg of Pb2+ per gram of adsorbent have been attained.

Rapid, high-temperature, field test method for evaluation of geothermal calcium carbonate scale inhibitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asperger, R.G.

1986-09-01

A new test method is described that allows the rapid field testing of calcium carbonate scale inhibitors at 500/sup 0/F (260/sup 0/C). The method evolved from use of a full-flow test loop on a well with a mass flow rate of about 1 x 10/sup 6/ lbm/hr (126 kg/s). It is a simple, effective way to evaluate the effectiveness of inhibitors under field conditions. Five commercial formulations were chosen for field evaluation on the basis of nonflowing, laboratory screening tests at 500/sup 0/F (260/sup 0/C). Four of these formulations from different suppliers controlled calcium carbonate scale deposition as measured bymore » the test method. Two of these could dislodge recently deposited scale that had not age-hardened. Performance-profile diagrams, which were measured for these four effective inhibitors, show the concentration interrelationship between brine calcium and inhibitor concentrations at which the formulations will and will not stop scale formation in the test apparatus. With these diagrams, one formulation was chosen for testing on the full-flow brine line. The composition was tested for 6 weeks and showed a dramatic decrease in the scaling occurring at the flow-control valve. This scaling was about to force a shutdown of a major, long-term flow test being done for reservoir economic evaluations. The inhibitor stopped the scaling, and the test was performed without interruption.« less

Influences of travertine dam formation on leaf litter decomposition and algal accrual

Treesearch

Codey D. Carter; Jane C. Marks

2007-01-01

At the time of this study Fossil Creek was being considered as a site for the restoration of a native fish assemblage, however there was concern amongst fisheries managers about the stream being food limited due to calcium carbonate (travertine) deposition. To evaluate the effects of travertine deposition on the aquatic food base we used leaf litterbags to compare...

The tufas of Pyramid Lake, Nevada

USGS Publications Warehouse

Benson, Larry V.

2004-01-01

Pyramid Lake is the site of some of the Earth's most spectacular tufa deposits. The Tufas are composed of calcium carbonate (CaCO3). The large tufa mounds, reef- and sheet-like tufas formed within Pyramid Lake, between 26,000 and 13,000 years (yr) ago, when the lake was part of pluvial Lake Lahontan. The mounds are composed of large interlocking spheres that contain multiple generations of a crystalline (thinolite) variety of tufa. Over time many of the mounds have fallen apart, exposing an internal network of tubes. The tubular structures are thought to have been created when springs discharged from the bottom of Pyramid Lake, supplying calcium that combined with carbonate dissolved in lake water to form the mounds. The reef- and sheet-like deposits contain pillow and pendant forms made up of a branching variety of tufa that often grades into dense layers or nodules. Dense layers of tufa also coat cobbles and boulders that were deposited in near-shore shallow-water areas. The thickest tufa deposits formed at lake-bottom sites of ground-water discharge and at overflow elevations1 where the lake was held at near-constant levels for long periods of time.

Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry.

PubMed

Berlind, T; Tengvall, P; Hultman, L; Arwin, H

2011-03-01

Thin films of amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride were deposited by reactive magnetron sputtering and optically characterized with spectroscopic ellipsometry. Complementary studies using scanning electron microscopy and atomic force microscopy were performed. The films were exposed to human serum albumin (HSA) and the adsorption was monitored in situ using dynamic ellipsometry. From the ellipsometric data the adsorbed amount of proteins was quantified in terms of surface mass density using de Feijter's model. The results indicate larger adsorption of proteins onto the amorphous films compared to the films with a more textured structure. Complementary studies with 125I-labeled HSA showed an apparent protein adsorption up to six times larger compared to the ellipsometry measurement. In addition, the four types of films were incubated in blood plasma followed by exposure to anti-fibrinogen, anti-HMWK or anti-C3c, revealing the materials' response to complement and contact activation. The amorphous and graphitic carbon nitride exhibit rather high immune activity compared to a titanium reference, whereas the amorphous carbon and the fullerene-like CNx show less immune complement deposition. Compared to the reference, all films exhibit indications of a stronger ability to initiate the intrinsic pathway of coagulation. Finally, the surfaces' bone-bonding ability was investigated by examination of their ability to form calcium phosphate crystals in a simulated body fluid, with a-CNx depositing most calcium phosphate after 21 days of incubation. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biomineralizations: insights and prospects from crustaceans

PubMed Central

Luquet, Gilles

2012-01-01

Abstract For growing, crustaceans have to molt cyclically because of the presence of a rigid exoskeleton. Most of the crustaceans harden their cuticle not only by sclerotization, like all the arthropods, but also by calcification. All the physiology of crustaceans, including the calcification process, is then linked to molting cycles. This means for these animals to find regularly a source of calcium ions quickly available just after ecdysis. The sources of calcium used are diverse, ranging from the environment where the animals live to endogenous calcium deposits cyclically elaborated by some of them. As a result, crustaceans are submitted to an important and energetically demanding calcium turnover throughout their life. The mineralization process occurs by precipitation of calcium carbonate within an organic matrix network of chitin-proteins fibers. Both crystalline and stabilized amorphous polymorphs of calcium carbonate are found in crustacean biominerals. Furthermore, Crustacea is the only phylum of animals able to elaborate and resorb periodically calcified structures. Notably for these two previous reasons, crustaceans are more and more extensively studied and considered as models of choice in the biomineralization research area. PMID:22536102

CHARACTERIZING CORAL CONDITION USING ESTIMATES OF THREE-DIMENSIONAL COLONY SURFACE AREA

EPA Science Inventory

Coral reefs provide shoreline protection, biological diversity, fishery harvets, and tourism, all values that stem from the physically-complex coral infrastructure. Stony corals (scleractinianss) construct and maintain the reef through deposition of calcium carbonate. Therefore...

Anachronistic facies from a drowned Lower Triassic carbonate platform: Lower member of the Alwa Formation (Ba'id Exotic), Oman Mountains

NASA Astrophysics Data System (ADS)

Woods, Adam D.; Baud, Aymon

2008-09-01

The lower member of the Alwa Formation (Lower Olenekian), found within the Ba'id Exotic in the Oman Mountains (Sultanate of Oman), consists of ammonoid-bearing, pelagic limestones that were deposited on an isolated, drowned carbonate platform on the Neotethyan Gondwana margin. The strata contain a variety of unusual carbonate textures and features, including thrombolites, Frutexites-bearing microbialites that contain synsedimentary cements, matrix-free breccias surrounded by isopachous calcite cement, and fissures and cavities filled with large botryoidal cements. Thrombolites are found throughout the study interval, and occur as 0.5-1.0 m thick lenses or beds that contain laterally laterally-linked stromatactis cavities. The Frutexites-bearing microbialites occur less frequently, and also form lenses or beds, up to 30 cm thick; the microbialites may be laminated, and often developed on hardgrounds. In addition, the Frutexites-bearing microbialites also contain synsedimentary calcite cement crusts and botryoids (typically < 1 cm thick) that harbour layers or pockets of what appear to be bacterial sheaths and coccoids, and are indicative of biologically mediated precipitation of the cement bodies. Slumping following lithification led to fracturing of the limestone and the precipitation of large, botryoidal aragonite cements in fissures that cut across the primary fabric. Environmental conditions, specifically palaeoxygenation and the degree of calcium carbonate supersaturation, likely controlled whether the thrombolites (high level of calcium carbonate supersaturation associated with vertical mixing of water masses and dysoxic conditions) or Frutexites-bearing microbialites (low level of calcium carbonate supersaturation associated with anoxic conditions and deposition below a stable chemocline) formed. The results of this study point to continued environmental stress in the region during the Early Triassic that likely contributed to the uneven recovery from the Permian-Triassic mass extinction.

The crustacean cuticle: structure, composition and mineralization.

PubMed

Nagasawa, Hiromichi

2012-01-01

Crustaceans have a rigid exoskeleton, which is made of a layered cuticle, covering the soft body parts for protection from conspecific competitors and/or interspecific predators. Calcium carbonate adds rigidity to the crustacean cuticle, which consequently means that growth only occur at each molt. The current study presents a review of existing literature on crustacean exoskeleton cuticle physiology and biochemistry in relation to the molting process with special reference to calcification. As a result, research matter where knowledge remains limited has been identified during the molting process, including 1) whether the same or different epithelial cells are responsible for the decomposition and/or reconstruction of chitin and proteins, 2) how calcium carbonate levels are regulated at the cellular level during transfer between the cuticle and body organs, and 3) what factors maintain the amorphous state of calcium carbonate following deposition in the exoskeleton and temporary storage organs. The identification of these areas of focus provides a basis on which targeted future research may be developed, and potentially applied to other invertebrate or even vertebrate processes.

Energy and environmental research emphasizing low-rank coal: Task 3.7, Fuel utilization properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zygarlicke, C.J.

Gasification-type entrained ash and deposits were produced in a pressurized test furnace at high temperature. For the subbituminous Black Thunder coal, the effect of fuel-rich conditions was an increase in quartz, calcite, dolomite, and calcium-rich phases in the entrained ash. Lower particle temperatures, as compared to full air conventional combustion, and the oxygen-lean atmosphere may have caused a reduction in the interaction and assimilation of pure quartz and organically bound calcium into calcium aluminosilicate phases. For the Illinois No. 6 entrained fly ash fuel-rich conditions prevented the oxidation of pyrite and pyrrhotite to iron oxide. Lower temperatures within and surroundingmore » char particles during reducing conditions combustion may have prevented the decomposition of pyrrhotite and enhanced the reaction of iron with aluminosilicate phases. The deposits show similar trends, with the Illinois No. 6 deposit grown under pressurized conditions at a lower temperature having Na and (Ca, Mg, Fe, Na, K) aluminosilicates, calcium carbonate, and an iron sulfide, probably pyrrohotite, present. At higher temperature, loss of sulfur occurs with the increased formation of iron aluminosilicate phases. The Illinois No. 6 and Black Thunder coals were tested with kaolin and lime additives under highly reducing conditions to simulate a gasification environment. The deposit collection zone temperature was varied from 750{degree}C to 1OOO{degree}C. Although no clear trends were evident for the interaction of kaolin or lime with the deposits, the deposits did become more porous, with greatly reduced strength shown for both additives.« less

Coral can have growth anomalies

EPA Science Inventory

Coral growth anomalies (GAs) are changes in the coral cells that deposit the calcium carbonate skeleton. They usually appear as raised areas of the skeleton and tissue that are different from the surrounding normal areas on the same colony. The features include abnormal shape a...

Liquid infused porous surfaces for mineral fouling mitigation.

PubMed

Charpentier, Thibaut V J; Neville, Anne; Baudin, Sophie; Smith, Margaret J; Euvrard, Myriam; Bell, Ashley; Wang, Chun; Barker, Richard

2015-04-15

Prevention of mineral fouling, known as scale, is a long-standing problem in a wide variety of industrial applications, such as oil production, water treatment, and many others. The build-up of inorganic scale such as calcium carbonate on surfaces and facilities is undesirable as it can result in safety risks and associated flow assurance issues. To date the overwhelming amount of research has mainly focused on chemical inhibition of scale bulk precipitation and little attention has been paid to deposition onto surfaces. The development of novel more environmentally-friendly strategies to control mineral fouling will most probably necessitate a multifunctional approach including surface engineering. In this study, we demonstrate that liquid infused porous surfaces provide an appealing strategy for surface modification to reduce mineral scale deposition. Microporous polypyrrole (PPy) coatings were fabricated onto stainless steel substrates by electrodeposition in potentiostatic mode. Subsequent infusion of low surface energy lubricants (fluorinated oil Fluorinert FC-70 and ionic liquid 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIm)) into the porous coatings results in liquid-repellent slippery surfaces. To assess their ability to reduce surface scaling the coatings were subjected to a calcium carbonate scaling environment and the scale on the surface was quantified using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). PPy surfaces infused with BMIm (and Fluorinert to a lesser extent) exhibit remarkable antifouling properties with the calcium carbonate deposition reduced by 18 times in comparison to untreated stainless steel. These scaling tests suggest a correlation between the stability of the liquid infused surfaces in artificial brines and fouling reduction efficiency. The current work shows the great potential of such novel coatings for the management of mineral scale fouling. Copyright © 2014 Elsevier Inc. All rights reserved.

Using in situ synchrotron radiation wide angle X-ray scattering (WAXS) to study CaCO3 scale formation at ambient and elevated temperature.

PubMed

Chen, Tao; Neville, Anne; Sorbie, Ken; Zhong, Zhong

2007-01-01

The formation of calcium carbonate mineral scale is a persistent and expensive problem in oil and gas production, water piping systems, power generator, and batch precipitation. The aim of this paper is to further the understanding of scale formation and inhibition by in situ probing of crystal growth by synchrotron radiation wide angle X-ray scattering (WAXS) at ambient and elevated temperature. This novel technique enables in situ study of mineral scale formation and inhibition and as such, information on the nucleation and growth processes are accessible. This technique studies bulk precipitation and surface deposition in the same system and will be of great benefit to the understanding of an industrial scaling system. It offers an exciting prospect for the study of scaling. It has been shown that the nucleation and growth of various calcareous polymorphs and their individual crystal planes can be followed in real-time and from this the following conclusions are reached. The process of scale deposition on the surface can be divided into an unstable phase and a stable phase. The initial phase of crystallization of calcium carbonate is characterized by instability with individual planes from various vaterite and aragonite polymorphs emerging and subsequently disappearing under the hydrodynamic conditions. After the initial unstable phase, various calcium carbonate crystal planes adhere on the surface and then grow on the surface. At 25 degrees C, the main plane of surface deposit is calcite and a strong (104) peak is detected. The other calcite planes (102), (006), (110) (113) and (202) are hardly detectable under this condition. At 80 degrees C, the main planes in the surface deposit are the (104), (113) and (110) planes of calcite. Stable planes of vaterite and aragonite are also observed. This paper will discuss how surface scale evolves--exploring the power of the synchrotron in situ methodology.

Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy

PubMed Central

Sathyavathi, R.; Saha, Anushree; Soares, Jaqueline S.; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

2015-01-01

Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93–98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance. PMID:25927331

Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy

NASA Astrophysics Data System (ADS)

Sathyavathi, R.; Saha, Anushree; Soares, Jaqueline S.; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

2015-04-01

Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93-98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance.

Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy.

PubMed

Sathyavathi, R; Saha, Anushree; Soares, Jaqueline S; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

2015-04-30

Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93-98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance.

Foraminiferal calcification and CO2

NASA Astrophysics Data System (ADS)

Nooijer, L. D.; Toyofuku, T.; Reichart, G. J.

2017-12-01

Ongoing burning of fossil fuels increases atmospheric CO2, elevates marine dissolved CO2 and decreases pH and the saturation state with respect to calcium carbonate. Intuitively this should decrease the ability of CaCO3-producing organisms to build their skeletons and shells. Whereas on geological time scales weathering and carbonate deposition removes carbon from the geo-biosphere, on time scales up to thousands of years, carbonate precipitation increases pCO2 because of the associated shift in seawater carbon speciation. Hence reduced calcification provides a potentially important negative feedback on increased pCO2 levels. Here we show that foraminifera form their calcium carbonate by active proton pumping. This elevates the internal pH and acidifies the direct foraminiferal surrounding. This also creates a strong pCO2 gradient and facilitates the uptake of DIC in the form of carbon dioxide. This finding uncouples saturation state from calcification and predicts that the added carbon due to ocean acidification will promote calcification by these organisms. This unknown effect could add substantially to atmospheric pCO2 levels, and might need to be accounted for in future mitigation strategies.

Evaluating the Contributions of Atmospheric Deposition of Carbon and Other Nutrients to Nitrification in Alpine Environments

NASA Astrophysics Data System (ADS)

Oldani, K. M.; Mladenov, N.; Williams, M. W.

2013-12-01

The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, which is the main energy source for microbial activity and sustenance of life. It has been shown that atmospheric deposition can contain high amounts of organic carbon (C). Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric organic C load. In this stage of the research we evaluated seasonal trends in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of snow, wet deposition, and dry deposition in an alpine environment at Niwot Ridge in the Rocky Mountains of Colorado to obtain a better understanding of the sources and chemical character of atmospheric deposition. Our results reveal a positive trend between dissolved organic carbon concentrations and calcium, nitrate and sulfate concentrations in wet and dry deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components that may be attributed to fluorescent pigments in bacteria. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate to alpine watersheds.

Multi-Functions of Carbonated Calcium Deficient Hydroxyapatite (CDHA)

NASA Astrophysics Data System (ADS)

Zhou, Huan

Natural bone is a complex composite mainly constituted of inorganic minerals and organic collagen molecules. Calcium phosphate (CaP) based materials have been proposed as the predominant bone substitute for bone tissue engineering applications due to their chemical similarity to bone mineral. Amorphous carbonated calcium deficient hydroxyapatite (CDHA) is an important compound among CaP materials because of the amorphous crystallite structure. The presence of extra ions in its lattice structure not only influences cell attachment and proliferation of osteoblasts, but also helps in bone metabolism. Biomimetic coating approach is the most widely used approach to produce CDHA coatings to implant. It is a process using simulated body fluid (SBF) to deposit bone-like CDHA coating to various material surfaces. The CDHA formation mechanism, SBF compositions and reacting conditions of biomimetic coating have already been sufficiently studied and compared in the past 20 years. It is an attempt in this thesis to explore new applications of SBF in biomedical research, focusing on different biomaterial applications: 1) based on the low temperature reaction condition of SBF, bisphosphonate incorporated CDHA coatings were deposited onto Ti6Al4V surface for the treatment of osteoporosis; 2) amorphous calcium phosphate nanospheres with extra elements in the lattice structure were prepared by a novel microwave assisted approach, providing a new potential of CaP materials production; 3) CDHA particles formed in SBF can be used as great fillers with biopolymers for preparing biocomposites for biomedical applications; 4) based on the high activity of CDHA amorphous structure and the stabilization ability of ethanol, yttrium and europium doped calcium phosphates were prepared using CDHA as a sacrificing template. In the end, future work based on these observations in the thesis is addressed, including areas of drug delivery, biocomposite fabrication and preparation of functionalized calcium phosphate materials.

Formation of amorphous calcium carbonate in caves and its implications for speleothem research.

PubMed

Demény, Attila; Németh, Péter; Czuppon, György; Leél-Őssy, Szabolcs; Szabó, Máté; Judik, Katalin; Németh, Tibor; Stieber, József

2016-12-22

Speleothem deposits are among the most valuable continental formations in paleoclimate research, as they can be dated using absolute dating methods, and they also provide valuable climate proxies. However, alteration processes such as post-depositional mineralogical transformations can significantly influence the paleoclimatic application of their geochemical data. An innovative sampling and measurement protocol combined with scanning and transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy is presented, demonstrating that carbonate precipitating from drip water in caves at ~10 °C contains amorphous calcium carbonate (ACC) that later transforms to nanocrystalline calcite. Stable oxygen isotope fractionations among calcite, ACC and water were also determined, proving that ACC is 18 O-depleted (by >2.4 ± 0.8‰) relative to calcite. This, in turn, has serious consequences for speleothem-based fluid inclusion research as closed system transformation of ACC to calcite may induce a negative oxygen isotope shift in fluid inclusion water, resulting in deterioration of the original compositions. ACC formation increases the speleothems' sensitivity to alteration as its interaction with external solutions may result in the partial loss of original proxy signals. Mineralogical analysis of freshly precipitating carbonate at the studied speleothem site is suggested in order to determine the potential influence of ACC formation.

Biomineralization of the spicules of sea urchin embryos.

PubMed

Wilt, Fred H

2002-03-01

The formation of calcareous skeletal elements by various echinoderms, especially sea urchins, offers a splendid opportunity to learn more about some processes involved in the formation of biominerals. The spicules of larvae of euechinoids have been the focus of considerable work, including their developmental origins. The spicules are composed of a single optical crystal of high magnesium calcite and variable amounts of amorphous calcium carbonate. Occluded within the spicule is a proteinaceous matrix, most of which is soluble; this matrix constitutes about 0.1% of the mass. The spicules are also enclosed by an extracellular matrix and are almost completely surrounded by cytoplasmic cords. The spicules are deposited by primary mesenchyme cells (PMCs), which accumulate calcium and secrete calcium carbonate. A number of proteins specific, or highly enriched, in PMCs, have been cloned and studied. Recent work supports the hypothesis that proteins found in the extracellular matrix of the spicule are important for biomineralization.

Controls on dripwater chemistry of Oregon Caves National Monument, northwestern United States

NASA Astrophysics Data System (ADS)

Rushdi, Ahmed I.; Ersek, Vasile; Mix, Alan C.; Clark, Peter U.

2018-02-01

Cave dripwater chemistry of Oregon Caves National Monument (OCNM) was studied, where the parameters pH, total alkalinity, calcium, magnesium, strontium, sodium and barium were analyzed at quasi-monthly intervals from 2005 to 2007. Different statistical analyses have been used to investigate the variability of the chemical parameters in the different sites in the OCNM cave system. The dripwater varies in response to seasonal changes in rainfall. The drip rates range from zero in summer to continuous flow in winter, closely following the rainfall intensity. Spatial variations of dripwater chemistry, which is nonlinearly related to dripwater discharge likely, reflect the chemical composition of bedrock and overlying soil, and the residence time of the ground water within the aquifer. The residence time of infiltrated water in bedrock cracks control the dissolution carbonate bedrock, reprecipitation of calcium carbonate and the degree of saturation of dripwater with respect to calcium carbonate minerals. Spatiotemporal fluctuations of dripwater Mg/Ca and Sr/Ca ratios are controlled by dissolution of carbonate bedrock and the degree of calcite reprecipitation in bedrock cracks. This suggests that trace elements in speleothem deposits at the OCNM may serve as paleoclimatological proxies for precipitation, if interpreted within the context of understanding local bedrock chemistry.

Subcellular localization of calcium deposits in the noble crayfish Astacus astacus spermatophore: Implications for post-mating spermatophore hardening and spermatozoon maturation.

PubMed

Niksirat, Hamid; Kouba, Antonín

2016-04-01

The freshly ejaculated spermatophore of crayfish undergoes a hardening process during post-mating storage on the body surface of female. The ultrastructural distribution of calcium deposits were studied and compared in freshly ejaculated and post-mating noble crayfish spermatophores, using the oxalate-pyroantimonate technique, to determine possible roles of calcium in post-mating spermatophore hardening and spermatozoon maturation. Small particles of sparsely distributed calcium deposits were visible in the wall of freshly ejaculated spermatophore. Also, large amount of calcium deposits were visible in the membranes of the freshly ejaculated spermatozoon. Five minutes post-ejaculation, granules in the spermatophore wall appeared as porous formations with numerous electron lucent spaces. Calcium deposits were visible within the spaces and scattered in the spermatophore wall matrix, where smaller calcium deposits combined to form globular calcium deposits. Large numbers of the globular calcium deposits were visible in the wall of the post-mating spermatophore. Smaller calcium deposits were detected in the central area of post-mating spermatophore, which contains the sperm mass, and in the extracellular matrix and capsule. While the density of calcium deposits decreased in the post-mating spermatozoon membranes, numerous small calcium deposits appeared in the subacrosomal zone and nucleus. Substantial changes in calcium deposit distribution in the crayfish spermatophore during post-mating storage on the body of female may be involved in the processes of the spermatophore hardening and spermatozoon maturation. © 2016 Wiley Periodicals, Inc.

Aragonite coating solutions (ACS) based on artificial seawater

NASA Astrophysics Data System (ADS)

Tas, A. Cuneyt

2015-03-01

Aragonite (CaCO3, calcium carbonate) is an abundant biomaterial of marine life. It is the dominant inorganic phase of coral reefs, mollusc bivalve shells and the stalactites or stalagmites of geological sediments. Inorganic and initially precipitate-free aragonite coating solutions (ACS) of pH 7.4 were developed in this study to deposit monolayers of aragonite spherules or ooids on biomaterial (e.g., UHMWPE, ultrahigh molecular weight polyethylene) surfaces soaked in ACS at 30 °C. The ACS solutions of this study have been developed for the surface engineering of synthetic biomaterials. The abiotic ACS solutions, enriched with calcium and bicarbonate ions at different concentrations, essentially mimicked the artificial seawater composition and started to deposit aragonite after a long (4 h) incubation period at the tropical sea surface temperature of 30 °C. While numerous techniques for the solution deposition of calcium hydroxyapatite (Ca10(PO4)6(OH)2), of low thermodynamic solubility, on synthetic biomaterials have been demonstrated, procedures related to the solution-based surface deposition of high solubility aragonite remained uncommon. Monolayers of aragonite ooids deposited at 30 °C on UHMWPE substrates soaked in organic-free ACS solutions were found to possess nano-structures similar to the mortar-and-brick-type botryoids observed in biogenic marine shells. Samples were characterized using SEM, XRD, FTIR, ICP-AES and contact angle goniometry.

RF magnetron sputtering of a hydroxyapatite target: A comparison study on polytetrafluorethylene and titanium substrates

NASA Astrophysics Data System (ADS)

Surmenev, Roman A.; Surmeneva, Maria A.; Grubova, Irina Yu.; Chernozem, Roman V.; Krause, Bärbel; Baumbach, Tilo; Loza, Kateryna; Epple, Matthias

2017-08-01

A pure hydroxyapatite (HA) target was used to prepare the biocompatible coating of HA on the surface of a polytetrafluorethylene (PTFE) substrate, which was placed on the same substrate holder with technically pure titanium (Ti) in the single deposition runs by radio-frequency (RF) magnetron sputtering. The XPS, XRD and FTIR analyses of the obtained surfaces showed that for all substrates, instead of the HA coating deposition, the coating of a mixture of calcium carbonate and calcium fluoride was grown. According to SEM investigations, the surface of PTFE was etched, and the surface topography of uncoated Ti was preserved after the depositions. The FTIR results reveal no phosphate bonds; only calcium tracks were observed in the EDX-spectra on the surface of the coated PTFE substrates. Phosphate oxide (V), which originated from the target, could be removed using a vacuum pump system, or no phosphate-containing bonds could be formed on the substrate surface because of the severe substrate bombardment process, which prevented the HA coating deposition. The observed results may be connected with the surface re-sputtering effect of the growing film by high-energy negatively charged ions (most probably oxygen or fluorine), which are accelerated in the cathode dark sheath.

Biofouling and microbial corrosion problem in the thermo-fluid heat exchanger and cooling water system of a nuclear test reactor.

PubMed

Rao, T S; Kora, Aruna Jyothi; Chandramohan, P; Panigrahi, B S; Narasimhan, S V

2009-10-01

This article discusses aspects of biofouling and corrosion in the thermo-fluid heat exchanger (TFHX) and in the cooling water system of a nuclear test reactor. During inspection, it was observed that >90% of the TFHX tube bundle was clogged with thick fouling deposits. Both X-ray diffraction and Mossbauer analyses of the fouling deposit demonstrated iron corrosion products. The exterior of the tubercle showed the presence of a calcium and magnesium carbonate mixture along with iron oxides. Raman spectroscopy analysis confirmed the presence of calcium carbonate scale in the calcite phase. The interior of the tubercle contained significant iron sulphide, magnetite and iron-oxy-hydroxide. A microbiological assay showed a considerable population of iron oxidizing bacteria and sulphate reducing bacteria (10(5) to 10(6) cfu g(-1) of deposit). As the temperature of the TFHX is in the range of 45-50 degrees C, the microbiota isolated/assayed from the fouling deposit are designated as thermo-tolerant bacteria. The mean corrosion rate of the CS coupons exposed online was approximately 2.0 mpy and the microbial counts of various corrosion causing bacteria were in the range 10(3) to 10(5) cfu ml(-1) in the cooling water and 10(6) to 10(8) cfu ml(-1) in the biofilm.

Microscopic physical biomarkers in carbonate hot springs: implications in the search for life on Mars

NASA Technical Reports Server (NTRS)

Allen, C. C.; Albert, F. G.; Chafetz, H. S.; Combie, J.; Graham, C. R.; Kieft, T. L.; Kivett, S. J.; McKay, D. S.; Steele, A.; Taunton, A. E.;

Liquefaction of calcium-containing subbituminous coals and coals of lower rank

DOEpatents

Gorbaty, Martin L.; Taunton, John W.

1980-01-01

A process for the treatment of a calcium-containing subbituminous coal and coals of lower rank to form insoluble, thermally stable calcium salts which remain within the solids portions of the residue on liquefaction of the coal, thereby suppressing the formation scale, made up largely of calcium carbonate deposits, e.g., vaterite, which normally forms within the coal liquefaction reactor (i.e., coal liquefaction zone), e.g., on reactor surfaces, lines, auxiliary equipment and the like. A solution of a compound or salt characterized by the formula MX, where M is a Group IA metal of the Periodic Table of the Elements, and X is an anion which is capable of forming water-insoluble, thermally stable calcium compounds, is maintained in contact with a particulate coal feed sufficient to impregnate said salt or compound into the pores of the coal. On separation of the impregnated particulate coal from the solution, the coal can be liquefied in a coal liquefaction reactor (reaction zone) at coal liquefaction conditions without significant formation of vaterite or other forms of calcium carbonate on reactor surfaces, auxiliary equipment and the like; and the Group IA metal which remains within the liquefaction bottoms catalyzes the reaction when the liquefaction bottoms are subjected to a gasification reaction.

Carbon nanotubes play an important role in the spatial arrangement of calcium deposits in hydrogels for bone regeneration.

PubMed

Cancian, Giulia; Tozzi, Gianluca; Hussain, Amirul Ashraf Bin; De Mori, Arianna; Roldo, Marta

2016-08-01

Age related bone diseases such as osteoporosis are considered among the main causes of reduced bone mechanical stability and bone fractures. In order to restore both biological and mechanical function of diseased/fractured bones, novel bioactive scaffolds that mimic the bone structure are constantly under development in tissue engineering applications. Among the possible candidates, chitosan-based thermosensitive hydrogel scaffolds represent ideal systems due to their biocompatibility, biodegradability, enhanced antibacterial properties, promotion of osteoblast formation and ease of injection, which makes them suitable for less invasive surgical procedures. As a main drawback, these chitosan systems present poor mechanical performance that could not support load-bearing applications. In order to produce more mechanically-competent biomaterials, the combined addition of hydroxyapatite and carbon nanotubes (CNTs) is proposed in this study. Specifically, the aim of this work is to develop thermosensitive chitosan hydrogels containing stabilised single-walled and multi-walled CNTs, where their effect on the mechanical/physiochemical properties, calcium deposition patterns and ability to provide a platform for the controlled release of protein drugs was investigated. It was found that the addition of CNTs had a significant effect on the sol-gel transition time and significantly increased the resistance to compression for the hydrogels. Moreover, in vitro calcification studies revealed that CNTs played a major role in the spatial arrangements of newly formed calcium deposits in the composite materials studied, suggesting that they may have a role in the way the repair of fragile and/or fractured bones occurs in vivo.

Lightweight, high-opacity paper : process costs and energy use reduction

Treesearch

John H. Klungness; Fabienne Pianta; Mathew L. Stroika; Marguerite Sykes; Freya Tan; Said AbuBakr

1999-01-01

Fiber loading is an environmentally friendly, energy efficient, and economical method for depositing precipitated calcium carbonate (PCC) partly within pulp fibers. Fiber loading can easily be done within the existing pulp processing system. This paper is a review of the process development from bench-scale to industrial-scale demonstrations, with additional...

Effect of cross-linked chitosan iron (III) on vascular calcification in uremic rats.

PubMed

de Castro, Barbara Bruna Abreu; do Carmo, Wander Barros; de Albuquerque Suassuna, Paulo Giovani; Carminatti, Moises; Brito, Julia Bianchi; Dominguez, Wagner Vasques; de Oliveira, Ivone Braga; Jorgetti, Vanda; Custodio, Melani Ribeiro; Sanders-Pinheiro, Helady

2018-05-01

Cross-linked chitosan iron (III) is a chitin-derived polymer with a chelating effect on phosphorus, but it is untested in vascular calcification. We evaluated this compound's ability to reduce hyperphosphatemia and its effect on vascular calcification in uremic rats using an adenine-based, phosphorus-rich diet for seven weeks. We used a control group to characterize the uremia. Uremic rats were divided according the treatment into chronic kidney disease, CKD-Ch-Fe(III)CL (CKD-Ch), CKD-calcium carbonate, or CKD-sevelamer groups. We measured creatinine, phosphorus, calcium, alkaline phosphatase, phosphorus excretion fraction, parathyroid hormone, and fibroblast growth factor 23. Vascular calcification was assessed using the aortic calcium content, and a semi-quantitative analysis was performed using Von Kossa and hematoxylin-eosin staining. At week seven, rats in the chronic kidney disease group had higher creatinine, phosphorus, phosphorus excretion fraction, calcium, alkaline phosphatase, fibroblast growth factor 23, and aortic calcium content than those in the Control group. Treatments with cross-linked chitosan iron (III) and calcium carbonate prevented phosphorus increase (20%-30% reduction). The aortic calcium content was lowered by 88% and 85% in the CKD-Ch and CKD-sevelamer groups, respectively. The prevalence of vascular changes was higher in the chronic kidney disease and CKD-calcium carbonate (62.5%) groups than in the CKD-Ch group (37.5%). In conclusion, cross-linked chitosan iron (III) had a phosphorus chelating effect similar to calcium carbonate already available for clinical use, and prevented calcium accumulation in the aorta. Impact statement Vascular calcification (VC) is a common complication due to CKD-related bone and mineral disorder (BMD) and is characterized by deposition of calcium in vessels. Effective therapies are not yet available but new phosphorus chelators can prevent complications from CV. We tested the effect of chitosan, a new phosphorus chelator, on the VC of uremic animals. It has recently been proposed that chitosan treatment may be effective in the treatment of hyperphosphataemia. However, its action on vascular calcification has not been investigated yet. In this study, we demonstrated that chitosan reduced the calcium content in the aorta, suggesting that this may be a therapeutic approach in the treatment of hyperphosphatemia by preventing CV.

Adhesion of in situ precipitated calcium carbonate in the presence and absence of magnetic field in quiescent conditions on different solid surfaces.

PubMed

Chibowski, Emil; Hołysz, Lucyna; Szcześ, Aleksandra

2003-11-01

Deposition of in situ precipitated calcium carbonate from Na(2)CO(3) and CaCl2 solutions on different substrates, i.e. stainless steel, copper, aluminium, and glass, was investigated at different temperatures, 20 degrees C, 40 degrees C, 60 degrees C and 80 degrees C, both in the absence and presence of S-S 0.1T magnetic field (MF). It was found that in quiescent conditions during 2h the amounts deposited firmly on the surfaces decreased with increasing temperature. If MF was present the deposition was reduced at all temperatures, and depended on the nature of the substrate. The largest MF effect was found on glass at 60 degrees C, which amounted 50% reduction of the deposit. However, at 80 degrees C no deposition was found in the presence of MF on aluminium surface. At this temperature the reproducibility of the experiments was poor, and an additional effect due to the metal surface corrosion (especially that of aluminium and copper) may be thought in alkaline environment of the experiments (pH ca. 10). Based on optical microscope photographs, it was concluded that the amounts of crystallographic forms of CaCO3 depended on the nature of substrate on which the precipitation and then the adhesion took place. To some extent the ratios of CaCO3 forms precipitated were different in the bulk phase than on the substrate surfaces at the same temperature, and this conclusion was based on the X-ray diffractograms. Some possible mechanisms causing MF effects are discussed.

Carbonate scale deactivating the biocathode in a microbial fuel cell

NASA Astrophysics Data System (ADS)

Santini, M.; Marzorati, S.; Fest-Santini, S.; Trasatti, S.; Cristiani, P.

2017-07-01

The development and the following inactivation of a carbon-based biocathode in single chamber and membraneless MFCs was investigated in this work. The electrochemical behavior of the biocathode has been analyzed over time during the MFC life. X-Ray Micro-Computed Tomographies (microCTs) have been carried out at progressive stages, documenting the building over time of a layer of scale deposition becoming thicker and thicker up to the cathode inactivation. The technique provides cross-sectional (tomographic) grayscale images and 3D reconstruction of volumes. Lighter color indicates lower X-ray attenuation (i.e., lower atomic density) thus allowing distinguishing biofilm from inorganic fouling on the basis of the average atomic number Z of each voxel (3D pixel). MicroCT was combined with Scanning Electron Microscopy (SEM) and Energy-Dispersive X-Ray Spectroscopy (EDX) in order to qualitatively recognize chemical species in each different layer of the cathode's section. Results correlated the presence of biofilm and calcium carbonate deposits, prevalently in the inner part of the cathode, with the produced electric current over time. A specific microCT-related software quantified the time-dependent carbonate scale deposition, identifying a correlation between the decreasing performances of the device and the increasing quantity of scale deposition that penetrates the cathode cross section in time.

SM50 Repeat-Polypeptides Self-Assemble into Discrete Matrix Subunits and Promote Appositional Calcium Carbonate Crystal Growth during Sea Urchin Tooth Biomineralization

PubMed Central

Mao, Yelin; Satchell, Paul G.; Luan, Xianghong; Diekwisch, Thomas G.H.

2015-01-01

The two major proteins involved in vertebrate enamel formation and echinoderm sea urchin tooth biomineralization, amelogenin and SM50, are both characterized by elongated polyproline repeat domains in the center of the macromolecule. To determine the role of polyproline repeat polypeptides in basal deuterostome biomineralization, we have mapped the localization of SM50 as it relates to crystal growth, conducted self-assembly studies of SM50 repeat polypeptides, and examined their effect on calcium carbonate and apatite crystal growth. Electron micrographs of the growth zone of Strongylocentrotus purpuratus sea urchin teeth documented a series of successive events from intravesicular mineral nucleation to mineral deposition at the interface between tooth surface and odontoblast syncytium. Using immunohistochemistry, SM50 was detected within the cytoplasm of cells associated with the developing tooth mineral, at the mineral secreting front, and adjacent to initial mineral deposits, but not in muscles and ligaments. Polypeptides derived from the SM50 polyproline alternating hexa- and hepta-peptide repeat region (SM50P6P7) formed highly discrete, donut-shaped self-assembly patterns. In calcium carbonate crystal growth studies, SM50P6P7 repeat peptides triggered the growth of expansive networks of fused calcium carbonate crystals while in apatite growth studies, SM50P6P7 peptides facilitated the growth of needle-shaped and parallel arranged crystals resembling those found in developing vertebrate enamel. In comparison, SM50P6P7 surpassed the PXX24 polypeptide repeat region derived from the vertebrate enamel protein amelogenin in its ability to promote crystal nucleation and appositional crystal growth. Together, these studies establish the SM50P6P7 polyproline repeat region as a potent regulator in the protein-guided appositional crystal growth that occurs during continuous tooth mineralization and eruption. In addition, our studies highlight the role of species-specific polyproline repeat motifs in the formation of discrete self-assembled matrices and the resulting control of mineral growth. PMID:26194158

SM50 repeat-polypeptides self-assemble into discrete matrix subunits and promote appositional calcium carbonate crystal growth during sea urchin tooth biomineralization.

PubMed

Mao, Yelin; Satchell, Paul G; Luan, Xianghong; Diekwisch, Thomas G H

2016-01-01

The two major proteins involved in vertebrate enamel formation and echinoderm sea urchin tooth biomineralization, amelogenin and SM50, are both characterized by elongated polyproline repeat domains in the center of the macromolecule. To determine the role of polyproline repeat polypeptides in basal deuterostome biomineralization, we have mapped the localization of SM50 as it relates to crystal growth, conducted self-assembly studies of SM50 repeat polypeptides, and examined their effect on calcium carbonate and apatite crystal growth. Electron micrographs of the growth zone of Strongylocentrotus purpuratus sea urchin teeth documented a series of successive events from intravesicular mineral nucleation to mineral deposition at the interface between tooth surface and odontoblast syncytium. Using immunohistochemistry, SM50 was detected within the cytoplasm of cells associated with the developing tooth mineral, at the mineral secreting front, and adjacent to initial mineral deposits, but not in muscles and ligaments. Polypeptides derived from the SM50 polyproline alternating hexa- and hepta-peptide repeat region (SM50P6P7) formed highly discrete, donut-shaped self-assembly patterns. In calcium carbonate crystal growth studies, SM50P6P7 repeat peptides triggered the growth of expansive networks of fused calcium carbonate crystals while in apatite growth studies, SM50P6P7 peptides facilitated the growth of needle-shaped and parallel arranged crystals resembling those found in developing vertebrate enamel. In comparison, SM50P6P7 surpassed the PXX24 polypeptide repeat region derived from the vertebrate enamel protein amelogenin in its ability to promote crystal nucleation and appositional crystal growth. Together, these studies establish the SM50P6P7 polyproline repeat region as a potent regulator in the protein-guided appositional crystal growth that occurs during continuous tooth mineralization and eruption. In addition, our studies highlight the role of species-specific polyproline repeat motifs in the formation of discrete self-assembled matrices and the resulting control of mineral growth. Copyright © 2015 Elsevier GmbH. All rights reserved.

21 CFR 184.1191 - Calcium carbonate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium carbonate. 184.1191 Section 184.1191 Food... GRAS § 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg. No. 471-34-1) is prepared by... of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of...

Lab-Scale Study of the Calcium Carbonate Dissolution and Deposition by Marine Cyanobacterium Phormidium subcapitatum

NASA Technical Reports Server (NTRS)

Karakis, S. G.; Dragoeva, E. G.; Lavrenyuk, T. I.; Rogochiy, A.; Gerasimenko, L. M.; McKay, D. S.; Brown, I. I.

2006-01-01

Suggestions that calcification in marine organisms changes in response to global variations in seawater chemistry continue to be advanced (Wilkinson, 1979; Degens et al. 1985; Kazmierczak et al. 1986; R. Riding 1992). However, the effect of [Na+] on calcification in marine cyanobacteria has not been discussed in detail although [Na+] fluctuations reflect both temperature and sea-level fluctuations. The goal of these lab-scale studies therefore was to study the effect of environmental pH and [Na+] on CaCO3 deposition and dissolution by marine cyanobacterium Phormidium subcapitatum. Marine cyanobacterium P. subcapitatum has been cultivated in ASN-III medium. [Ca2+] fluctuations were monitored with Ca(2+) probe. Na(+) concentrations were determined by the initial solution chemistry. It was found that the balance between CaCO3 dissolution and precipitation induced by P. subcapitatum grown in neutral ASN III medium is very close to zero. No CaCO3 precipitation induced by cyanobacterial growth occurred. Growth of P. subcapitatum in alkaline ASN III medium, however, was accompanied by significant oscillations in free Ca(2+) concentration within a Na(+) concentration range of 50-400 mM. Calcium carbonate precipitation occurred during the log phase of P. subcapitatum growth while carbonate dissolution was typical for the stationary phase of P. subcapitatum growth. The highest CaCO3 deposition was observed in the range of Na(+) concentrations between 200-400 mM. Alkaline pH also induced the clamping of P. subcapitatum filaments, which appeared to have a strong affinity to envelop particles of chemically deposited CaCO3 followed by enlargement of those particles size. EDS analysis revealed the presence of Mg-rich carbonate (or magnesium calcite) in the solution containing 10-100 mM Na(+); calcite in the solution containing 200 mM Na(+); and aragonite in the solution containing with 400 mM Na(+). Typical present-day seawater contains xxmM Na(+). Early (Archean) seawater was likely less saline. The division of marine cyanobacterium P. subcapitatum is associated with periodic deposition and dissolution of CaCO3, the rhythms and intensity of which are dependent on concentrations of both OH(-) and Na(+). Thus, the role of present-day marine cyanobacteria in the global carbonate cycle might be reduced to aggregation and recrystallization of available CaCO3 particles in marine water rather than long-term precipitation and accumulation of CaCO3 deposits. For lower Na(+) concentrations, precipitation of carbonates by cyanobacteria would be even less significant. These results suggest that the lack of calcified cyanobacteria in stromatalite-bearing Precambrian sequences can be explained not only by high dissolved inorganic carbon concentrations but also by lower salinity, as well as possible lower pH compared to present-day oceans.

Effect of long-term microgravity on the mineralisation of inner ear otoliths of fish - a spaceflight study

NASA Astrophysics Data System (ADS)

Anken, Ralf

The "heavy bodies" (i.e., statoliths or otoliths, mainly made up of calcium carbonate and protein) in the inner ears of vertebrates transform the physical parameter "gravity" to biological signals needed for postural control. It has been shown earlier that hypergravity slows down inner ear otolith growth in developing fish (via a down-regulation of carbonic anhydrase reactivity) as an adaptation towards altered environmental gravity. We were thus prompted to elucidate whether long-term microgravity would possibly yield opposite effects. Therefore, larval siblings of cichlid fish (Oreochromis mossambicus) were housed in a bioregenerative life support system (OMEGAHAB) using green algae (Euglena gracilis) for oxygen supply. The experiment was successfully flown on the FOTON M-3 mission. Prior to launch, otoliths were stained with a fluorescent calcium tracer (Alizarin Complexone). This treatment both allowed an assessment of otolith growth (size) after recovery as well as an analysis of relocations of calcium deposits. Calcium and strontium contents were determined using inductively coupled plasma mass spectrometry. The results will be communicated at the meeting. Acknowledgement: This work was financially supported by the German Aerospace Center (DLR) (FKZ: 50 WB 0527).

Raman microspectrometry of laser-reshaped rabbit auricular cartilage: preliminary study on laser-induced cartilage mineralization

NASA Astrophysics Data System (ADS)

Heger, Michal; Mordon, Serge R.; Leroy, Gérard; Fleurisse, Laurence; Creusy, Collette

2006-03-01

Laser-assisted cartilage reshaping (LACR) is a relatively novel technique designed to noninvasively and permanently restructure cartilaginous tissue. It is believed that heat-induced stress relaxation, in which a temperature-mediated disruption of H2O binding is associated with conformational alterations in the proteoglycan and collagen-rich matrix, constitutes the underlying mechanism of LACR. Several reports have suggested that laser-mediated cartilage mineralization may contribute to the permanent shape change of laser-reshaped cartilage. In an effort to validate these results in the context of Er:glass LACR, we performed a preliminary Raman microspectrometric study to characterize the crystal deposits in laser-irradiated chondrocytes and extracellular matrix. For the first time, we identified intracellular calcium sulfate deposits and extracellular calcium phosphate (apatite) crystals in laser-reshaped rabbit auricular cartilage. Calcium carbonate deposits are localized in both irradiated and nonirradiated samples, suggesting that this mineral plays no role in conformational retention. In our discussion, we elaborate on the possible molecular and cellular mechanisms responsible for intra- and extracellular crystallization, and propose a novel hypothesis on the formation of apatite, inasmuch as the biological function of this mineral (providing structure and rigidity in bones and dental enamel) may be extrapolated to the permanent shape change of laser-irradiated cartilage.

Molding mineral within microporous hydrogels by a polymer-induced liquid-precursor (PILP) process.

PubMed

Cheng, Xingguo; Gower, Laurie B

2006-01-01

Natural biominerals often have exquisite morphologies, where the cells exercise a high degree of crystallographic control through secretion of biological macromolecules and regulation of ion transport. One important example is the sea urchin spine. It has recently been shown to be formed through deposition of a transient amorphous calcium carbonate (ACC) precursor phase that later transforms to single-crystalline calcite, ultimately forming an elaborate three-dimensional microporous calcium carbonate structure with interconnected pores. Macromolecules associated with the mineral phase are thought to play a key role in regulating this transformation. The work described here mimics this type of morphological control by "molding" an amorphous calcium carbonate precursor within a porous poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel that has been prepared as a negative replica from the void space of an urchin spine. Using an acidic biomimetic polymer as a process-directing agent, we show that polyaspartic acid induces amorphous calcium carbonate (ACC) nanoparticles, which have fluidic character and therefore are able to infiltrate the PHEMA hydrogel replica and coalesce into the convoluted morphology that replicates the original microporous structure of the sea urchin spine. By "molding" calcium carbonate into a complex morphology at room temperature, using a precursor process that is induced by a biomimetic acidic macromolecule, the PILP process is a useful in vitro model for examining different aspects of the amorphous-to-crystalline transformation process that is apparently used by a variety of biomineralizing organisms. For example, although we were able to replicate the overall morphology of the spine, it had polycrystalline texture; further studies with this system will focus on controlling the nucleation event, which may help to elucidate how such a convoluted structure can be prepared with single-crystalline texture via an amorphous precursor. Through a better understanding of the mechanisms used by organisms to regulate crystal properties, such biomimetic processes can lead to the synthesis of materials with superior electronic, mechanical, and optical properties.

Overview of the amorphous precursor phase strategy in biomineralization

NASA Astrophysics Data System (ADS)

Weiner, Steve; Mahamid, Julia; Politi, Yael; Ma, Yurong; Addadi, Lia

2009-06-01

It was assumed for a long time that organisms produce minerals directly from a saturated solution. A few exceptions were known, including the well documented mineralized teeth of the chiton. In 1997 it was demon-strated that sea urchin larvae form their calcitic spicules by first depositing a highly unstable mineral phase called amorphous calcium carbonate. This strategy has since been shown to be used by animals from other phyla and for both aragonite and calcite. Recent evidence shows that vertebrate bone mineral may also be formed via a precursor phase of amorphous calcium carbonate. This strategy thus appears to be widespread. The challenge now is to understand the mechanisms by which these unstable phases are initially formed, how they are temporarily stabilized and how they are destabilized and transform into a crystalline mature product.

Origin of phosphatic stromatolites in the Upper Cretaceous condensed sequence of the Polish Jura Chain

NASA Astrophysics Data System (ADS)

Krajewski, K. P.; Leśniak, P. M.; Łącka, B.; Zawidzki, P.

2000-10-01

The Turonian stromatolite-bearing condensed sequence in the Polish Jura Chain (the European epicontinental basin) provides good insight into the environment of formation of Cretaceous phosphatic stromatolites, owing to their purely phosphatic development and negligible post-depositional alteration. The sequence developed as a result of slow pelagic sedimentation and microbial mat phosphatization on a submarine swell surrounded by local basins with non-condensed carbonate deposition. Diagenesis of organic matter and dissolution of biogenic apatite were the major sources of reactive phosphorus for the microbial mat phosphatization. Stromatolite growth occurred due to pulses of amorphous or poorly ordered calcium phosphate precipitation followed by crystallization of carbonate fluorapatite (CFA). The phosphogenic environment left an imprint on the isotopic composition of limestone carbon and lattice-bound carbon and sulphur in CFA, and on the light rare-earth element (LREE) distribution in CFA. The δ13C of the stromatolite-bearing sequence shows a negative excursion (-1 to -3‰), standing in marked contrast to positive carbon values of the surrounding basinal carbonate. Most of the δ34S values of CFA (+20 to +21‰) fit the value range of the coeval seawater sulphate, and the LREE distribution shows a well-defined seawater pattern. This geochemical signature is indicative of intense diagenesis of organic matter at the seafloor, pelagic carbonate dissolution, and prolonged exposure of the deposited phosphate towards the water column. The enhanced deposition and diagenesis of organic phosphorus in the stromatolitic environment reflects elevated levels of the epicontinental basin nutrification related to sea-level rises and the associated oceanographic and geochemical changes.

Effect of carbon coating on spontaneous C12A7 whisker formation

NASA Astrophysics Data System (ADS)

Zaikovskii, Vladimir I.; Volodin, Alexander M.; Stoyanovskii, Vladimir O.; Cherepanova, Svetlana V.; Vedyagin, Aleksey A.

2018-06-01

A carbon nanoreactor concept was applied to study the stabilization effect of carbon shell on phase composition and morphology of dodecacalcium hepta-aluminate Ca12Al14O33. The starting C12A7 powder was obtained using aluminum and calcium hydroxides as precursors. Carbon shell was formed by a chemical vapor deposition of divinyl at 550 °C. After the calcination at 1400 °C, the product was characterized by X-ray diffraction analysis (XRD) and high resolution transmission electron microscopy (HRTEM). It was observed for a first time that spontaneous formation of calcium aluminate whiskers take place under the conditions described. Each whisker consists of a 'head' (globular particle of 0.5 microns in diameter) and a 'tail' (prolonged whisker of few microns in length and 0.1-0.2 microns in diameter). According to HRTEM, the 'head' is characterized with microcrystal lattice of Ca12Al14O33 compound. XRD data show the presence of CaAl2O4 phase traces. The 'head' and 'tail' of the whisker are covered with structured graphene layers of 10 nm and 3 nm, correspondingly.

On the role of the central nervous system in regulating the mineralisation of inner-ear otoliths of fish.

PubMed

Anken, Ralf H

2006-12-01

Stato- or otoliths are calcified structures in the organ of balance and equilibrium of vertebrates, the inner ear, where they enhance its sensitivity to gravity. The compact otoliths of fish are composed of the calcium carbonate polymorph aragonite and a small fraction of organic molecules. The latter form a protein skeleton which determines the morphology of an otolith as well as its crystal lattice structure. This short review addresses findings according to which the brain obviously plays a prominent role in regulating the mineralisation of fish otoliths and depends on the gravity vector. Overall, otolith mineralisation has thus been identified to be a unique, neuronally guided biomineralisation process. The following is a hypothetical model for regulation of calcification by efferent vestibular neurons: (1) release of calcium at tight junctions in the macular epithelia, (2) macular carbonic anhydrase activity (which in turn is responsible for carbonate deposition), (3) chemical composition of matrix proteins. The rationale and evidence that support this model are discussed.

Acoustic and Hydrodynamic Cavitations for Nano CaCO3 Synthesis

NASA Astrophysics Data System (ADS)

Sonawane, Shirish H.; Kulkarni, Ravindra D.

Calcium carbonate is a common inorganic compound known as limestone. Calcium carbonate has many applications in industries such as medicine, agriculture, paint plastic and surface coatings etc. The vast majority of calcium carbonate used in industry is extracted by mining process. Pure calcium carbonate (e.g. for food or pharmaceutical use), is synthesized by passing carbon dioxide into a solution of calcium hydroxide slurry. In this process calcium carbonate precipitates out, and this grade of product is referred to as precipitate calcium carbonate (abbreviated as PCC).

Patterns of coccolithophore pigment change under global acidification conditions based on in-situ observations at BATS site between July 1990-Dec 2008

NASA Astrophysics Data System (ADS)

Lv, Jianhai; Kuang, Yaoqiu; Zhao, Hui; Andersson, Andreas

2017-06-01

Coccolith production is an important part of the biogenic carbon cycle as the largest source of calcium carbonate on earth, accounting for about 75% of the deposition of carbon on the sea floor. Recent studies based on laboratory experiment results indicated that increasing anthropogenic CO2 in the atmosphere triggered global ocean acidification leading to a decrease of calcite or aragonite saturation and calcium carbonate, and to decreasing efficiency of carbon export/pumping to deep layers. In the present study, we analyzed about 20 years of field observations of coccolithophore pigment, dissolved inorganic carbon (DIC), nutrients, and temperatures from the Bermuda Atlantic Time-series Study (BATS) site and satellite remote sensing to investigate the variable tendency of the coccolithophore pigment, and to evaluate the influence of ocean acidification on coccolithophore biomass. The results indicated that there was a generally increasing tendency of coccolithophore pigment, coupled with increasing bicarbonate concentrations or decreasing carbonate ion concentration. The change of coccolithophore pigment was also closely associated with pH, nutrients, mixed layer depth (MLD), and temperature. Correlation analyses between coccolithophores and abiotic parameter imply that coccoliths production or coccolithophore pigment has increased with increasing acidification in the recent 20 years.

The calcium isotope evolution of Lake Lisan, the Dead Sea glacial precursor

NASA Astrophysics Data System (ADS)

Bradbury, H. J.; Turchyn, A. V.; Wong, K.; Torfstein, A.

2016-12-01

Calcium is a stoichiometric component of carbonate minerals whose calcium isotopic composition reflects changes in the calcium isotope composition of the water from which it precipitates as well as the calcium isotope fractionation factor during precipitation. The lacustrine deposits of the last glacial Dead Sea (Lisan Formation) are dominated by carbonate minerals (aragonite) that record the geochemical history of the lake. The sediment sequence comprises alternating laminae of aragonite and clay-rich marls, interspersed with primary gypsum beds and disseminated secondary gypsum crystals. The aragonite precipitated annually during high lake stands associated with wet periods, while the primary gypsum precipitated during low lake conditions (arid periods). We report the calcium isotopic composition (δ44Ca in ‰ relative to bulk silicate earth) of primary aragonite laminae, primary gypsum and secondary gypsum at 1-5kyr resolution throughout the Lisan Formation sampled at the Masada section (70 - 14.5 ka). The δ44Ca of the primary gypsum averages +0.29‰, and displays smaller temporal variations than the aragonite, which averages -0.35‰ but ranges between +0.18‰ and -0.68‰. The aragonite δ44Ca changes temporally in sync with the previously reconstructed lake level suggesting the aragonite δ44Ca reflects changes in the lake calcium balance during lake level changes. The secondary gypsum composition (-0.3‰) corresponds to coeval aragonite samples. For the secondary gypsum to have a similar δ44Ca to the aragonite it is likely that the calcium derived from the aragonite in a near quantitative fashion through recrystallization of the aragonite to gypsum. A numerical box model is used to explore the effect of changing lake water levels on the calcium isotope composition of the aragonite and gypsum over the time interval studied.

Calcium Carbonate

MedlinePlus

... Maalox® (as a combination product containing Calcium Carbonate, Simethicone) ... Relief (as a combination product containing Calcium Carbonate, Simethicone) ... Plus (as a combination product containing Calcium Carbonate, Simethicone)

Production of carbonate sediments by a unicellular green alga

USGS Publications Warehouse

Yates, K.K.; Robbins, L.L.

1998-01-01

This study investigates the ability of the unicellular green alga Natmochloris atoimis to precipitate CaCO3, quantifies mineral precipitation rates, estimates sediment production in a N. atomiis bloom, and discusses the implications of microbial calcification for carbonate sediment deposition. A series of N. atomus cultures, isolated from Lake Reeve, Australia, were incubated at various pH and calcium concentrations to determine environmental parameters for calcification. Rates of calcification were calculated from initial and postincubation alkalinity, pH, and calcium measurements. Replicate experiments and controls consisting of non-calcifying cultures, uninoculated media, and dead cell cultures were performed using environmental culture parameters determined in series cultures. Average calcification rates from replicate experiments were used to predict daily sediment production rates in a small bloom of N. atomus. N. atomus precipitates 0.138 g/L of calcite in approximately 4 h when incubated at pH 8.5, 14.24 mM calcium concentration, 33 ??C, 100 ??E/m2/s light intensity, and a cell population density of 107 cells/mL. Assuming continuous precipitation, this corresponds to a maximum estimated sediment production rate of 1.6 ?? 106 kg of CaCO3, per 12 h day in a single bloom of 3.2 ?? 109 L. Our results suggest that microbial calcification contributes significantly to the carbonate sediment budget.

Bacterially induced mineralization of calcium carbonate: the role of exopolysaccharides and capsular polysaccharides.

PubMed

Ercole, Claudia; Cacchio, Paola; Botta, Anna Lucia; Centi, Valeria; Lepidi, Aldo

2007-02-01

Bacterially induced carbonate mineralization has been proposed as a new method for the restoration of limestones in historic buildings and monuments. We describe here the formation of calcite crystals by extracellular polymeric substances isolated from Bacillus firmus and Bacillus sphaericus. We isolated bacterial outer structures (glycocalix and parietal polymers), such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) and checked for their influence on calcite precipitation. CPS and EPS extracted from both B. firmus and B. sphaericus were able to mediate CaCO3 precipitation in vitro. X-ray microanalysis showed that in all cases the formed crystals were calcite. Scanning electron microscopy showed that the shape of the crystals depended on the fractions utilized. These results suggest the possibility that biochemical composition of CPS or EPS influences the resulting morphology of CaCO3. There were no precipitates in the blank samples. CPS and EPS comprised of proteins and glycoproteins. Positive alcian blue staining also reveals acidic polysaccharides in CPS and EPS fractions. Proteins with molecular masses of 25-40 kDa and 70 kDa in the CPS fraction were highly expressed in the presence of calcium oxalate. This high level of synthesis could be related to the binding of calcium ions and carbonate deposition.

Calcium content of different compositions of gallstones and pathogenesis of calcium carbonate gallstones.

PubMed

Yu, Ji-Kuen; Pan, Huichin; Huang, Shing-Moo; Huang, Nan-Lan; Yao, Chung-Chin; Hsiao, Kuang-Ming; Wu, Chew-Wun

2013-01-01

Our aim was to investigate the calcium content of different gallstone compositions and the pathogenic mechanisms of calcium carbonate gallstones. Between August 2001 and July 2007, gallstones from 481 patients, including 68 calcium carbonate gallstones, were analyzed for total calcium content. Gallbladder bile samples from 33 cases and six controls were analyzed for pH, carbonate anion level, free-ionized calcium concentration and saturation index for calcium carbonate. Total calcium content averaged 75.6 %, 11.8 %, and 4.2 % for calcium carbonate, calcium bilirubinate and cholesterol gallstones. In 29.4 % of patients, chronic and/or intermittent cystic duct obstructions were caused by polypoid lesions in the neck region and 70.6 % were caused by stones. A total of 82 % of patients had chronic low-grade inflammation of the gallbladder wall and 18.0 % had acute inflammatory exacerbations. In the bile, we found the mean pH, mean carbonate anion, free-ionized calcium concentrations, and mean saturation index for calcium carbonate to be elevated in comparison to controls. From our study, we found chronic and/or intermittent cystic duct obstructions and low-grade GB wall inflammation lead to GB epithelium hydrogen secretion dysfunction. Increased calcium ion efflux into the GB lumen combined with increased carbonate anion presence increases SI_CaCO(3) from 1 to 22.4. Thus, in an alkaline milieu with pH 7.8, calcium carbonate begins to aggregate and precipitate. Copyright © 2012. Published by Elsevier B.V.

Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vengosh, A.; Chivas, A.R.; McCulloch, M.T.

1991-10-01

The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The variations of {delta}{sup 11}B may be controlled by isotopic exchange of boron species in which {sup 10}B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in themore » calcium carbonates. The B content and {delta}{sup 11}B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 {plus minus} 0.9 {times} 10{sup 10} g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 {times} 10{sup 10} g/yr) and approximately half that of altered oceanic crust (14 {times} 10{sup 10} g/yr). Thus, carbonates are an important sink for B in the oceans being {approximately}20% of the total sinks. The preferential incorporation of {sup 10}B into calcium carbonate results in oceanic {sup 11}B-enrichment, estimated as 1.2 {plus minus} 0.3 {times} 10{sup 12} per mil {center dot} g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record.« less

Growth of calcium hydroxyapatite (Ca-HAp) on cholesterol and cholestanol crystals from a simulated body fluid: A possible insight into the pathological calcifications associated with atherosclerosis.

PubMed

Laird, Dougal F; Mucalo, Michael R; Yokogawa, Yoshiyuki

2006-03-15

An experimental study into calcium phosphate (CP) nucleation and growth on cholesterol and cholestanol surfaces from a supersaturated simulated body fluid (SBF) is presented with the overall aim of gaining some fundamental insights into the pathological calcifications associated with atherosclerosis. Soaking of pressed cholesterol disks at physiological temperature in SBF solutions was found to lead to CP nucleation and growth if the disks were surface roughened and if an SBF with concentrations of the calcium and hydrogen phosphate ions at 2.25x physiological concentrations was used. The CP phase deposited was shown via SEM micrographs to possess a florette type morphology akin to that observed in earlier reported studies. The use of recrystallised cholesterol and cholestanol microcrystals as substrates for soaking in SBF facilitated the observation of CP deposition. In general, cholesterol recrystallised from polar solvents like 95% ethanol as a cholesterol monohydrate phase which was a better substrate for CP growth than cholesterol recrystallised from more non-polar solvents (e.g., benzene) which produced anhydrous cholesterol phases. CP was also observed to form on recrystallised cholestanol microcrystals, a molecule closely related to cholesterol. Inductively coupled plasma optical emission spectrometry (ICP-OES) data gave confirmation that Ca:P mole ratios of the grown CP were 1.3-1.5 suggesting a mixed phase of octacalcium phosphate (OCP) and Ca-deficient HAp and that the CP coating grows (with time of soaking) on the substrates after nucleation in the SBF growth medium. Infrared (IR) spectra of the extracted coatings from the cholesterol substrates confirmed that the CP phase deposited is a semi crystalline HAp with either carbonate substituted into its structure or else co-deposited as calcium carbonate. Soaking experiments involving modified cholesterol substrates in which the OH group in the molecule was replaced with the oleiyl or phosphonate group showed no CP nucleation and growth. This observation illustrates the importance of the known epitaxial relationship between cholesterol and HAp (which theoretically predicts favourable deposition of one phase upon the other) and the consequences of its destruction (by chemical modification of the cholesterol). In the case of the phosphorylated cholesterol, failure of this substrate to nucleate CP phases may have also been caused by the reduction in concentration of free solution Ca2+ in the SBF medium by complexation with the phosphonate groups on the phosphorylated cholesterol. This would have reduced the ion product of Ca2+ and inorganic phosphate and lowered the degree of supersaturation in the SBF medium.

Size controlled hydroxyapatite and calcium carbonate particles: synthesis and their application as templates for SERS platform.

PubMed

Parakhonskiy, B V; Svenskaya, Yu I; Yashchenok, A М; Fattah, H A; Inozemtseva, O A; Tessarolo, F; Antolini, R; Gorin, D A

2014-06-01

An elegant route for hydroxyapatite (HA) particle synthesis via ionic exchange reaction is reported. Calcium carbonate particles (CaCO3) were recrystallized into HA beads in water solution with phosphate ions. The size of initial CaCO3 particles was controlled upon the synthesis by varying the amount of ethylene glycol (EG) in aqueous solution. The average size of HA beads ranged from 0.6±0.1 to 4.3±1.1μm. Silver nanoparticles were deposited on the surface of HA and CaCO3 particles via silver mirror reaction. Surface enhanced Raman scattering of silver functionalized beads was demonstrated by detecting Rhodamine B. CaCO3 and HA particles have a great potential for design of carrier which can provide diagnostic and therapeutic functions. Copyright © 2014 Elsevier B.V. All rights reserved.

Structure, mineralogy, and microbial diversity of geothermal spring microbialites associated with a deep oil drilling in Romania.

PubMed

Coman, Cristian; Chiriac, Cecilia M; Robeson, Michael S; Ionescu, Corina; Dragos, Nicolae; Barbu-Tudoran, Lucian; Andrei, Adrian-Ştefan; Banciu, Horia L; Sicora, Cosmin; Podar, Mircea

2015-01-01

Modern mineral deposits play an important role in evolutionary studies by providing clues to the formation of ancient lithified microbial communities. Here we report the presence of microbialite-forming microbial mats in different microenvironments at 32°C, 49°C, and 65°C around the geothermal spring from an abandoned oil drill in Ciocaia, Romania. The mineralogy and the macro- and microstructure of the microbialites were investigated, together with their microbial diversity based on a 16S rRNA gene amplicon sequencing approach. The calcium carbonate is deposited mainly in the form of calcite. At 32°C and 49°C, the microbialites show a laminated structure with visible microbial mat-carbonate crystal interactions. At 65°C, the mineral deposit is clotted, without obvious organic residues. Partial 16S rRNA gene amplicon sequencing showed that the relative abundance of the phylum Archaea was low at 32°C (<0.5%) but increased significantly at 65°C (36%). The bacterial diversity was either similar to other microbialites described in literature (the 32°C sample) or displayed a specific combination of phyla and classes (the 49°C and 65°C samples). Bacterial taxa were distributed among 39 phyla, out of which 14 had inferred abundances >1%. The dominant bacterial groups at 32°C were Cyanobacteria, Gammaproteobacteria, Firmicutes, Bacteroidetes, Chloroflexi, Thermi, Actinobacteria, Planctomycetes, and Defferibacteres. At 49°C, there was a striking dominance of the Gammaproteobacteria, followed by Firmicutes, Bacteroidetes, and Armantimonadetes. The 65°C sample was dominated by Betaproteobacteria, Firmicutes, [OP1], Defferibacteres, Thermi, Thermotogae, [EM3], and Nitrospirae. Several groups from Proteobacteria and Firmicutes, together with Halobacteria and Melainabacteria were described for the first time in calcium carbonate deposits. Overall, the spring from Ciocaia emerges as a valuable site to probe microbes-minerals interrelationships along thermal and geochemical gradients.

Structure, mineralogy, and microbial diversity of geothermal spring microbialites associated with a deep oil drilling in Romania

PubMed Central

Coman, Cristian; Chiriac, Cecilia M.; Robeson, Michael S.; Ionescu, Corina; Dragos, Nicolae; Barbu-Tudoran, Lucian; Andrei, Adrian-Ştefan; Banciu, Horia L.; Sicora, Cosmin; Podar, Mircea

2015-01-01

Modern mineral deposits play an important role in evolutionary studies by providing clues to the formation of ancient lithified microbial communities. Here we report the presence of microbialite-forming microbial mats in different microenvironments at 32°C, 49°C, and 65°C around the geothermal spring from an abandoned oil drill in Ciocaia, Romania. The mineralogy and the macro- and microstructure of the microbialites were investigated, together with their microbial diversity based on a 16S rRNA gene amplicon sequencing approach. The calcium carbonate is deposited mainly in the form of calcite. At 32°C and 49°C, the microbialites show a laminated structure with visible microbial mat-carbonate crystal interactions. At 65°C, the mineral deposit is clotted, without obvious organic residues. Partial 16S rRNA gene amplicon sequencing showed that the relative abundance of the phylum Archaea was low at 32°C (<0.5%) but increased significantly at 65°C (36%). The bacterial diversity was either similar to other microbialites described in literature (the 32°C sample) or displayed a specific combination of phyla and classes (the 49°C and 65°C samples). Bacterial taxa were distributed among 39 phyla, out of which 14 had inferred abundances >1%. The dominant bacterial groups at 32°C were Cyanobacteria, Gammaproteobacteria, Firmicutes, Bacteroidetes, Chloroflexi, Thermi, Actinobacteria, Planctomycetes, and Defferibacteres. At 49°C, there was a striking dominance of the Gammaproteobacteria, followed by Firmicutes, Bacteroidetes, and Armantimonadetes. The 65°C sample was dominated by Betaproteobacteria, Firmicutes, [OP1], Defferibacteres, Thermi, Thermotogae, [EM3], and Nitrospirae. Several groups from Proteobacteria and Firmicutes, together with Halobacteria and Melainabacteria were described for the first time in calcium carbonate deposits. Overall, the spring from Ciocaia emerges as a valuable site to probe microbes-minerals interrelationships along thermal and geochemical gradients. PMID:25870594

Structure, mineralogy, and microbial diversity of geothermal spring microbialites associated with a deep oil drilling in Romania

DOE PAGES

Coman, Cristian; Chiriac, Cecilia M.; Robeson, Michael S.; ...

2015-03-30

Modern mineral deposits play an important role in evolutionary studies by providing clues to the formation of ancient lithified microbial communities. Here we report the presence of microbialite-forming microbial mats in different microenvironments at 32°C, 49°C, and 65°C around the geothermal spring from an abandoned oil drill in Ciocaia, Romania. The mineralogy and the macro- and microstructure of the microbialites were investigated, together with their microbial diversity based on a 16S rRNA gene amplicon sequencing approach. The calcium carbonate is deposited mainly in the form of calcite. At 32°C and 49°C, the microbialites show a laminated structure with visible microbialmore » mat-carbonate crystal interactions. At 65°C, the mineral deposit is clotted, without obvious organic residues. Partial 16S rRNA gene amplicon sequencing showed that the relative abundance of the phylum Archaea was low at 32°C (<0.5%) but increased significantly at 65°C (36%). The bacterial diversity was either similar to other microbialites described in literature (the 32°C sample) or displayed a specific combination of phyla and classes (the 49°C and 65°C samples). Bacterial taxa were distributed among 39 phyla, out of which 14 had inferred abundances >1%. The dominant bacterial groups at 32°C were Cyanobacteria, Gammaproteobacteria, Firmicutes, Bacteroidetes, Chloroflexi, Thermi, Actinobacteria, Planctomycetes, and Defferibacteres. At 49°C, there was a striking dominance of the Gammaproteobacteria, followed by Firmicutes, Bacteroidetes, and Armantimonadetes. The 65°C sample was dominated by Betaproteobacteria, Firmicutes, [OP1], Defferibacteres, Thermi, Thermotogae, [EM3], and Nitrospirae. Lastly, several groups from Proteobacteria and Firmicutes, together with Halobacteria and Melainabacteria were described for the first time in calcium carbonate deposits. Overall, the spring from Ciocaia emerges as a valuable site to probe microbes-minerals interrelationships along thermal and geochemical gradients.« less

On the structure of amorphous calcium carbonate--a detailed study by solid-state NMR spectroscopy.

PubMed

Nebel, Holger; Neumann, Markus; Mayer, Christian; Epple, Matthias

2008-09-01

The calcium carbonate phases calcite, aragonite, vaterite, monohydrocalcite (calcium carbonate monohydrate), and ikaite (calcium carbonate hexahydrate) were studied by solid-state NMR spectroscopy ( (1)H and (13)C). Further model compounds were sodium hydrogencarbonate, potassium hydrogencarbonate, and calcium hydroxide. With the help of these data, the structure of synthetically prepared additive-free amorphous calcium carbonate (ACC) was analyzed. ACC contains molecular water (as H 2O), a small amount of mobile hydroxide, and no hydrogencarbonate. This supports the concept of ACC as a transient precursor in the formation of calcium carbonate biominerals.

Comparison of abundances of chemical elements in mineralized and unmineralized sandstone of the Brushy Basin Member of the Morrison Formation, Smith Lake District, Grants uranium region, New Mexico

USGS Publications Warehouse

Pierson, C.T.; Spirakis, C.S.; Robertson, J.F.

1983-01-01

Statistical treatment of analytical data from the Mariano Lake and Ruby uranium deposits in the Smith Lake district, New Mexico, indicates that organic carbon, arsenic, barium, calcium, cobalt, copper, gallium, iron, lead, manganese, molybdenum, nickel, selenium, strontium, sulfur, vanadium, yttrium, and zirconium are concentrated along with uranium in primary ore. Comparison of the Smith Lake data with information from other primary deposits in the Grants uranium region and elsewhere in the Morrison Formation of the Colorado Plateau suggests that these elements, with the possible exceptions of zirconium and gallium and with the probable addition of aluminum and magnesium, are typically associated with primary, tabular uranium deposits. Chemical differences between the Ruby and Mariano Lake deposits are consistent with the interpretation that the Ruby deposit has been more affected by post-mineralization oxidizing solutions than has the Mariano Lake deposit.

The effect of brushing with nano calcium carbonate and calcium carbonate toothpaste on the surface roughness of nano-ionomer

NASA Astrophysics Data System (ADS)

Anisja, D. H.; Indrani, D. J.; Herda, E.

2017-08-01

Nanotechnology developments in dentistry have resulted in the development of nano-ionomer, a new restorative material. The surface roughness of restorative materials can increase bacteria adhesion and lead to poor oral hygiene. Abrasive agents in toothpaste can alter tooth and restorative material surfaces. The aim of this study is to identify the effect of brushing with nano calcium carbonate, and calcium carbonate toothpaste on surface roughness of nano-ionomer. Eighteen nano-ionomer specimens were brushed with Aquabidest (doubledistilled water), nano calcium carbonate and calcium carbonate toothpaste. Brushing lasted 30 minutes, and the roughness value (Ra) was measured after each 10 minute segment using a surface roughness tester. The data was analyzed using repeated ANOVA and one-way ANOVA test. The value of nano-ionomer surface roughness increased significantly (p<0.05) after 20 minutes of brushing with the nano calcium carbonate toothpaste. Brushing with calcium carbonate toothpaste leaves nano-ionomer surfaces more rugged than brushing with nano calcium carbonate toothpaste.

Inhibition of calcium carbonate deposition on stainless steel using olive leaf extract as a green inhibitor.

PubMed

Aidoud, Roumaissa; Kahoul, Abdelkrim; Naamoune, Farid

2017-01-01

The antiscale properties of the aqueous extract of olive (Olea europaea L.) leaves as a natural scale inhibitor for stainless steel surface in Hammam raw water were investigated using chronoamperometry (CA) and electrochemical impedance spectroscopy techniques in conjunction with a microscopic examination. The X-ray diffraction analysis reveals that the scale deposited over the pipe walls consists of pure CaCO 3 calcite. The CA, in accordance with electrochemical impedance spectra and scanning electron microscopy, shows that the inhibition efficiency increases with increasing extract concentration. This efficiency is considerably reduced as the temperature is increased.

Contaminant Dynamics and Trends in Hyperalkaline Urban Streams

NASA Astrophysics Data System (ADS)

Riley, Alex; Mayes, William

2015-04-01

Streams in post-industrial urban areas can have multiple contemporary and historic pressures impacting upon their chemical and ecological status. This paper presents analysis of long term data series (up to 36 years in length) from two small streams in northern England (catchment areas 0.5-0.6km2). Around 3.5 million m3 of steel making slags and other wastes were deposited in the headwater areas of the Howden Burn and Dene Burn in northeast England up to the closure of the workings in the early 1980s. This has led to streams draining from the former workings which have a hyperalkaline ambient pH (mean of 10.3 in both streams), elevated alkalinity (up to 487 mg/L as CaCO3) from leaching of lime and other calcium oxides / silicates within the slag, and enrichment of some trace elements (e.g. aluminium (Al), lithium (Li) and zinc (Zn)) including those which form oxyanions mobile at high pH such as vanadium (V). The high ionic strength of the waters and calcium enrichment also leads to waters highly supersaturated with calcium carbonate. Trace contaminant concentrations are strongly positively correlated, and concentrations generally diminish with increased flow rate suggesting the key source of metals in the system is the highly alkaline groundwater draining from the slag mounds. Some contaminants (notably Cr and ammonium) increase with high flow suggesting sources related to urban runoff and drainage from combined sewer overflows into one of the catchments. Loading estimates instream show that many of the contaminants (e.g. Al, V and Zn) are rapidly attenuated in secondary calcium carbonate-dominated deposits that precipitate vigorously on the streambeds with rates of up to 250 g CaCO3/m2/day. These secondary sinks limit the mobility of many contaminants in the water column, while concentrations in secondary deposits are relatively low given the rapid rates at which Ca is also attenuated. Long-term trend analysis showed modest declines in calcium and alkalinity over the monitoring period and these are not accompanied by significant declines in water pH. If the monotonic trends of decline in alkalinity and calcium continue in the largest of the receiving streams, it will be in the region of 50-80 years before calcite precipitation would be expected to be close to baseline levels, where ecological impacts would be negligible. The data show the value of long-term water quality datasets in managing post-industrial catchments where there may be multiple pressures on water quality.

Characterization of the calcification of cardiac valve bioprostheses by environmental scanning electron microscopy and vibrational spectroscopy.

PubMed

Delogne, Christophe; Lawford, Patricia V; Habesch, Steven M; Carolan, Vikki A

2007-10-01

Bioprosthetic heart valve tissue and associated calcification were studied in their natural state, using environmental scanning electron microscopy (ESEM). Energy dispersive X-ray micro-analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopy were used to characterize the various calcific deposits observed with ESEM. The major elements present in calcified valves were also analyzed by inductively coupled plasma-optical emission spectroscopy. To better understand the precursor formation of the calcific deposits, results from the elemental analyses were statistically correlated. ESEM revealed the presence of four broad types of calcium phosphate crystal morphology. In addition, two main patterns of organization of calcific deposits were observed associated with the collagen fibres. Energy dispersive X-ray micro-analysis identified the crystals observed by ESEM as salts containing mainly calcium and phosphate with ratios from 1.340 (possibly octacalcium phosphate, which has a Ca/P ratio of 1.336) to 2.045 (possibly hydroxyapatite with incorporation of carbonate and metal ion contaminants, such as silicon and magnesium, in the crystal lattice). Raman and fourier-transform infrared spectroscopy also identified the presence of carbonate and the analyses showed spectral features very similar to a crystalline hydroxyapatite spectrum, also refuting the presence of precursor phases such as beta-tricalcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate. The results of this study raised the possibility of the presence of precursor phases associated with the early stages of calcification.

CALCIUM BINDING TO INTESTINAL MEMBRANES

PubMed Central

Oschman, James L.; Wall, Betty J.

1972-01-01

Flame photometry reveals that glutaraldehyde and buffer solutions in routine use for electron microscopy contain varying amounts of calcium. The presence of electron-opaque deposits adjacent to membranes in a variety of tissues can be correlated with the presence of calcium in the fixative. In insect intestine (midgut), deposits occur adjacent to apical and lateral plasma membranes. The deposits are particularly evident in tissues fixed in glutaraldehyde without postosmication. They are also observed in osmicated tissue if calcium is added to wash and osmium solutions. Deposits are absent when calcium-free fixatives are used, but are present when traces of CaCl2 (as low as 5 x 10-5 M) are added. The deposits occur at regular intervals along junctional membranes, providing images strikingly similar to those obtained by other workers who have used pyroantimonate in an effort to localize sodium. Other divalent cations (Mg++, Sr++, Ba++, Mn++, Fe++) appear to substitute for calcium, while sodium, potassium, lanthanum, and mercury do not. After postfixing with osmium with calcium added, the deposits can be resolved as patches along the inner leaflet of apical and lateral plasma membranes. The dense regions may thus localize membrane constituents that bind calcium. The results are discussed in relation to the role of calcium in control of cell-to-cell communication, intestinal calcium uptake, and the pyroantimonate technique for ion localization. PMID:4569411

Determination of the carbonate dissolution mechanism of Lactococcus sp.

NASA Astrophysics Data System (ADS)

Yanmiş, Derya; Orhan, Furkan; Güllüce, Medine; Şahin, Fikrettin

2017-04-01

Magnesite, the main source for magnesium and magnesium derivatives, are also commonly used in the production of caustic, dead-burned and fused magnesia. World magnesite resources are estimated to be at 12 billion tonnes mostly located in China, Russia, North Korea, Australia and Turkey. Turkey is the second producer of the magnesite. Magnesite deposits in Turkey are sedimentary magnesite which have been formed in specific conditions as high concentrations of MgSO4 and CO2 and presence of certain organic salts or created by hot or cold dissolution connected with carbonate rocks mainly with dolomites. According to the genesis of magnesite deposits, they have some impurities as calcium, quartz, iron, etc. Impurities of magnesite, especially CaCO3, reduce its economic value and industrial usability. In our previous study, we have performed biotechnologically enrichment of magnesite by Lactococcus sp., which gave significantly important results. However, we had no information about carbonate dissolution mechanism of bacteria. Therefore, it is aimed to reveal the metabolites of Lactococcus sp. and mechanism leading to the carbonate dissolution (MgCO3 and CaCO3).

Carrier-inside-carrier: polyelectrolyte microcapsules as reservoir for drug-loaded liposomes.

PubMed

Maniti, Ofelia; Rebaud, Samuel; Sarkis, Joe; Jia, Yi; Zhao, Jie; Marcillat, Olivier; Granjon, Thierry; Blum, Loïc; Li, Junbai; Girard-Egrot, Agnès

2015-01-01

Conventional liposomes have a short life-time in blood, unless they are protected by a polymer envelope, most often polyethylene glycol. However, these stabilizing polymers frequently interfere with cellular uptake, impede liposome-membrane fusion and inhibit escape of liposome content from endosomes. To overcome such drawbacks, polymer-based systems as carriers for liposomes are currently developed. Conforming to this approach, we propose a new and convenient method for embedding small size liposomes, 30-100 nm, inside porous calcium carbonate microparticles. These microparticles served as templates for deposition of various polyelectrolytes to form a protective shell. The carbonate particles were then dissolved to yield hollow polyelectrolyte microcapsules. The main advantage of using this method for liposome encapsulation is that carbonate particles can serve as a sacrificial template for deposition of virtually any polyelectrolyte. By carefully choosing the shell composition, bioavailability of the liposomes and of the encapsulated drug can be modulated to respond to biological requirements and to improve drug delivery to the cytoplasm and avoid endosomal escape.

Hydrocarbon Deposition Attenuates Osteoblast Activity on Titanium

PubMed Central

Hayashi, R.; Ueno, T.; Migita, S.; Tsutsumi, Y.; Doi, H.; Ogawa, T.; Hanawa, T.; Wakabayashi, N.

2014-01-01

Although the reported percentage of bone-implant contact is far lower than 100%, the cause of such low levels of bone formation has rarely been investigated. This study tested the negative biological effect of hydrocarbon deposition onto titanium surfaces, which has been reported to be inevitable. Osteogenic MC3T3-E1 cells were cultured on titanium disks on which the carbon concentration was experimentally regulated to achieve carbon/titanium (C/Ti) ratios of 0.3, 0.7, and 1.0. Initial cellular activities such as cell attachment and cell spreading were concentration-dependently suppressed by the amount of carbon on the titanium surface. The osteoblastic functions of alkaline phosphatase activity and calcium mineralization were also reduced by more than 40% on the C/Ti (1.0) surface. These results indicate that osteoblast activity is influenced by the degree of hydrocarbon contamination on titanium implants and suggest that hydrocarbon decomposition before implant placement may increase the biocompatibility of titanium. PMID:24868012

Increased calcium absorption from synthetic stable amorphous calcium carbonate: Double-blind randomized crossover clinical trial in post-menopausal women

USDA-ARS?s Scientific Manuscript database

Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (C...

Seawater calcium isotope ratios across the Eocene-Oligocene transition

USGS Publications Warehouse

Griffith, E.M.; Paytan, A.; Eisenhauer, A.; Bullen, T.D.; Thomas, E.

2011-01-01

During the Eocene-Oligocene transition (EOT, ca. 34 Ma), Earth's climate cooled significantly from a greenhouse to an icehouse climate, while the calcite (CaCO3) compensation depth (CCD) in the Pacific Ocean increased rapidly. Fluctuations in the CCD could result from various processes that create an imbalance between calcium (Ca) sources to, and sinks from, the ocean (e.g., weathering and CaCO3 deposition), with different effects on the isotopic composition of dissolved Ca in the oceans due to differences in the Ca isotopic composition of various inputs and outputs. We used Ca isotope ratios (??44/40Ca) of coeval pelagic marine barite and bulk carbonate to evaluate changes in the marine Ca cycle across the EOT. We show that the permanent deepening of the CCD was not accompanied by a pronounced change in seawater ??44/40Ca, whereas time intervals in the Neogene with smaller carbonate depositional changes are characterized by seawater ??44/40Ca shifts. This suggests that the response of seawater ??44/40Ca to changes in weathering fluxes and to imbalances in the oceanic alkalinity budget depends on the chemical composition of seawater. A minor and transient fluctuation in the Ca isotope ratio of bulk carbonate may reflect a change in isotopic fractionation associated with CaCO3 precipitation from seawater due to a combination of factors, including changes in temperature and/or in the assemblages of calcifying organisms. ?? 2011 Geological Society of America.

Induced calcium carbonate precipitation using Bacillus species.

PubMed

Seifan, Mostafa; Samani, Ali Khajeh; Berenjian, Aydin

2016-12-01

Microbially induced calcium carbonate precipitation is an emerging process for the production of self-healing concrete. This study was aimed to investigate the effects and optimum conditions on calcium carbonate biosynthesis. Bacillus licheniformis, Bacillus sphaericus, yeast extract, urea, calcium chloride and aeration were found to be the most significant factors affecting the biomineralization of calcium carbonate. It was noticed that the morphology of microbial calcium carbonate was mainly affected by the genera of bacteria (cell surface properties), the viscosity of the media and the type of electron acceptors (Ca 2+ ). The maximum calcium carbonate concentration of 33.78 g/L was achieved at the optimum conditions This value is the highest concentration reported in the literature.

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to discharges...

Evidence for Late Permian-Upper Triassic ocean acidification from calcium isotopes in carbonate of the Kamura section in Japan

NASA Astrophysics Data System (ADS)

Ye, F.; Zhao, L., Sr.; Chen, Z. Q.; Wang, X.

2017-12-01

Calcium and carbon cycles are tightly related in the ocean, for example, through continental weathering and deposition of carbonate, thus, very important for exploring evolutions of marine environment during the earth history. The end-Permian mass extinction is the biggest biological disaster in the Phanerozoic and there are several studies talking about variations of calcium isotopes across the Permian-Triassic boundary (PTB). However, these studies are all from the Tethys regions (Payne et al., 2010; Hinojosa et al., 2012), while the Panthalassic Ocean is still unknown to people. Moreover, evolutions of the calcium isotopes during the Early to Late Triassic is also poorly studied (Blattler et al., 2012). Here, we studied an Uppermost Permian to Upper Triassic shallow water successions (Kamura section, Southwest Japan) in the Central Panthalassic Ocean. The Kamura section is far away from the continent without any clastic pollution, therefore, could preserved reliable δ44/40Cacarb signals. Conodont zonation and carbonate carbon isotope also provide precious time framework which is necessary for the explaining of the δ44/40Cacarb profile. In Kamura, δ44/40Cacarb and δ13Ccarb both exhibit negative excursions across the PTB, the δ44/40Cacarb value in the end-Permian is 1.0398‰ then abrupt decrease to the minimum value of 0.1524‰. CO2-driven global ocean acidification best explains the coincidence of the δ44/40Cacarb excursion with negative excursions in the δ13Ccarb of carbonates until the Early Smithian(N1a, N1b, N1c, P1, N2, P2). In the Middle and the Late Triassic, the δ44/40 Cacarb average approximately 1.1‰. During the Middle and Late Triassic, strong relationships between δ44/40Cacarb and δ13Ccarb are collapsed, indicating a normal pH values of the seawater in those time. The Siberian Trap volcanism probably played a significant role on the δ44/40Cacarb until the late Early Triassic. After that, δ44/40Cacarb was mostly controlled by carbonate flux.

The expanded amelogenin polyproline region preferentially binds to apatite versus carbonate and promotes apatite crystal elongation

PubMed Central

Gopinathan, Gokul; Jin, Tianquan; Liu, Min; Li, Steve; Atsawasuwan, Phimon; Galang, Maria-Therese; Allen, Michael; Luan, Xianghong; Diekwisch, Thomas G. H.

2014-01-01

The transition from invertebrate calcium carbonate-based calcite and aragonite exo- and endoskeletons to the calcium phosphate-based vertebrate backbones and jaws composed of microscopic hydroxyapatite crystals is one of the great revolutions in the evolution of terrestrial organisms. To identify potential factors that might have played a role in such a transition, three key domains of the vertebrate tooth enamel protein amelogenin were probed for calcium mineral/protein interactions and their ability to promote calcium phosphate and calcium carbonate crystal growth. Under calcium phosphate crystal growth conditions, only the carboxy-terminus augmented polyproline repeat peptide, but not the N-terminal peptide nor the polyproline repeat peptide alone, promoted the formation of thin and parallel crystallites resembling those of bone and initial enamel. In contrast, under calcium carbonate crystal growth conditions, all three amelogenin-derived polypeptides caused calcium carbonate to form fused crystalline conglomerates. When examined for long-term crystal growth, polyproline repeat peptides of increasing length promoted the growth of shorter calcium carbonate crystals with broader basis, contrary to the positive correlation between polyproline repeat element length and apatite mineralization published earlier. To determine whether the positive correlation between polyproline repeat element length and apatite crystal growth versus the inverse correlation between polyproline repeat length and calcium carbonate crystal growth were related to the binding affinity of the polyproline domain to either apatite or carbonate, a parallel series of calcium carbonate and calcium phosphate/apatite protein binding studies was conducted. These studies demonstrated a remarkable binding affinity between the augmented amelogenin polyproline repeat region and calcium phosphates, and almost no binding to calcium carbonates. In contrast, the amelogenin N-terminus bound to both carbonate and apatite, but preferentially to calcium carbonate. Together, these studies highlight the specific binding affinity of the augmented amelogenin polyproline repeat region to calcium phosphates versus calcium carbonate, and its unique role in the growth of thin apatite crystals as they occur in vertebrate biominerals. Our data suggest that the rise of apatite-based biominerals in vertebrates might have been facilitated by a rapid evolution of specialized polyproline repeat proteins flanked by a charged domain, resulting in apatite crystals with reduced width, increased length, and tailored biomechanical properties. PMID:25426079

Effect of Strength Enhancement of Soil Treated with Environment-Friendly Calcium Carbonate Powder

PubMed Central

Park, Kyungho; Jun, Sangju; Kim, Daehyeon

2014-01-01

This study aims to investigate the effects of the strength improvement of soft ground (sand) by producing calcium carbonate powder through microbial reactions. To analyze the cementation effect of calcium carbonate produced through microbial reaction for different weight ratios, four different types of specimens (untreated, calcium carbonate, cement, and calcium carbonate + cement) with different weight ratios (2%, 4%, 6%, and 8%) were produced and cured for a period of 3 days, 7 days, 14 days, 21 days, and 28 days to test them. The uniaxial compression strength of specimens was measured, and the components in the specimen depending on the curing period were analyzed by means of XRD analysis. The result revealed that higher weight ratios and longer curing period contributed to increased strength of calcium carbonate, cement, and calcium carbonate + cement specimens. The calcium carbonate and the calcium carbonate + cement specimens in the same condition showed the tendency of decreased strength approximately 3 times and two times in comparison with the 8% cement specimens cured for 28 days, but the tendency of increased strength was approximately 4 times and 6 times in comparison with the untreated specimen. PMID:24688401

Effect of strength enhancement of soil treated with environment-friendly calcium carbonate powder.

PubMed

Park, Kyungho; Jun, Sangju; Kim, Daehyeon

2014-01-01

This study aims to investigate the effects of the strength improvement of soft ground (sand) by producing calcium carbonate powder through microbial reactions. To analyze the cementation effect of calcium carbonate produced through microbial reaction for different weight ratios, four different types of specimens (untreated, calcium carbonate, cement, and calcium carbonate + cement) with different weight ratios (2%, 4%, 6%, and 8%) were produced and cured for a period of 3 days, 7 days, 14 days, 21 days, and 28 days to test them. The uniaxial compression strength of specimens was measured, and the components in the specimen depending on the curing period were analyzed by means of XRD analysis. The result revealed that higher weight ratios and longer curing period contributed to increased strength of calcium carbonate, cement, and calcium carbonate + cement specimens. The calcium carbonate and the calcium carbonate + cement specimens in the same condition showed the tendency of decreased strength approximately 3 times and two times in comparison with the 8% cement specimens cured for 28 days, but the tendency of increased strength was approximately 4 times and 6 times in comparison with the untreated specimen.

Precipitation Rate Investigation on synthesis of precipitated calcium carbonate

NASA Astrophysics Data System (ADS)

Sulistiyono, E.; Handayani, M.; Firdiyono, F.; Fajariani, E. N.

2018-03-01

Study on the formation of precipitated calcium carbonate from natural limestone Sukabumi with the influenced of various parameters such as precipitation rate, concentration of CaCl2 and amplitudes were investigated. We also investigated the result with the precipitated calcium carbonate from Merck (p.a) for comparison. The higher concentration of CaCl2 would give effect to the lower of the precipitation rate. It was observed that precipitation rate of calcium carbonate from limestone Sukabumi at concentration of 0.08 molar was 3.66 cm/minutes and showing the optimum condition, while the precipitation rate of calcium carbonate Merck at the concentration 0.08 molar was 3.53 cm/minutes. The characterization of precipitated calcium carbonate was done using X-ray fluorescence (XRF) and scanning electron microscope (SEM). The characterization using XRF showed that CaO content of precipitated calcium carbonate from natural limestone Sukabumi had high purity of 99.16%. The particle distribution using scanning electron microscope (SEM) showed that precipitated calcium carbonate from natural limestone Sukabumi revealed 1.79 µm – 11.46 µm, meanwhile the particle distribution of precipitated calcium carbonate Merck showed larger particles with the size of 3.22 µm – 10.68 µm.

[Does carbonate originate from carbonate-calcium crystal component of the human urinary calculus?].

PubMed

Yuzawa, Masayuki; Nakano, Kazuhiko; Kumamaru, Takatoshi; Nukui, Akinori; Ikeda, Hitoshi; Suzuki, Kazumi; Kobayashi, Minoru; Sugaya, Yasuhiro; Morita, Tatsuo

2008-09-01

It gives important information in selecting the appropriate treatment for urolithiasis to confirm the component of urinary calculus. Presently component analysis of the urinary calculus is generally performed by infrared spectroscopy which is employed by companies providing laboratory testing services in Japan. The infrared spectroscopy determines the molecular components from the absorption spectra in consequence of atomic vibrations. It has the drawback that an accurate crystal structure cannot be analyzed compared with the X-ray diffraction method which analyzes the crystal constituent based on the diffraction of X-rays on crystal lattice. The components of the urinary calculus including carbonate are carbonate apatite and calcium carbonate such as calcite. Although the latter is reported to be very rare component in human urinary calculus, the results by infrared spectroscopy often show that calcium carbonate is included in calculus. The infrared spectroscopy can confirm the existence of carbonate but cannot determine whether carbonate is originated from carbonate apatite or calcium carbonate. Thus, it is not clear whether calcium carbonate is included in human urinary calculus component in Japan. In this study, we examined human urinary calculus including carbonate by use of X-ray structural analysis in order to elucidate the origin of carbonate in human urinary calculus. We examined 17 human calculi which were reported to contain calcium carbonate by infrared spectroscopy performed in the clinical laboratory. Fifteen calculi were obtained from urinary tract, and two were from gall bladder. The stones were analyzed by X-ray powder method after crushed finely. The reports from the clinical laboratory showed that all urinary culculi consisted of calcium carbonate and calcium phosphate, while the gallstones consisted of calcium carbonate. But the components of all urinary calculi were revealed to be carbonate apatite by X-ray diffraction. The components of gallstones were shown to be calcium carbonate (one calcite and the other aragonite) not only by infrared spectroscopy but by X-ray diffraction. It was shown that component analysis of the calculus could be more accurately performed by adding X-ray diffraction method to infrared spectroscopy. It was shown that calcium carbonate existed in a gallstone. As for the carbonate in human urinary calculi, present study showed that it was not calcium carbonate origin but carbonate apatite origin.

21 CFR 582.1191 - Calcium carbonate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This...

Using Calcium Isotopic Composition of Calcium Carbonate Veins to Assess the Roles of Vein Formation and Seafloor Alteration in Regulation of the Carbon Cycle

NASA Astrophysics Data System (ADS)

Chen, F.; Coggon, R. M.; Teagle, D. A. H.; Turchyn, A. V.

2016-12-01

Calcium carbonate vein formation in the oceanic crust has been proposed as a climate-sensitive feedback mechanism that regulates the carbon cycle on million-year timescales. The suggestion has been that higher pCO2 levels may drive changes in ocean temperature and pH that increase seafloor alteration, releasing more calcium from oceanic basalt. This results in more removal of carbon from Earth's surface through calcium carbonate formation, which includes calcium carbonate vein formation in oceanic crust. The importance of this feedback mechanism remains enigmatic. Measurements of the δ44Ca of calcium carbonate veins in the oceanic crust may constrain the sources of calcium and timing of vein formation. Seawater and basalt are the only sources present shortly after crustal formation, whereas other sources, such as anhydrite dissolution and sedimentary carbonates become available when the crust ages, at which point carbonate veins may form far from the ridge axis. We report the calcium isotopic composition of 65 calcium carbonate veins, ranging from 108 to 1.2 million years old, in hydrothermally altered basalt from the Mid-Atlantic and Juan de Fuca ridges. We also present 43 δ44Ca measurements of 5.9 million year old basalts and dikes from the Costa Rica Rift that have undergone hydrothermal alteration over a range of conditions in upper crust. The δ44Ca of the calcium carbonate veins ranges from -1.59 to 1.01‰ (versus Bulk Silicate Earth), whereas the δ44Ca of altered basalts ranges from -0.18 to 0.28‰. Depth and temperature of formation seem to be major influences on calcium carbonate vein δ44Ca, with veins formed at cool, shallower depths having higher δ44Ca, closer to seawater. In contrast, we note no temporal variation in δ44Ca of calcium carbonate veins when comparing samples from older and younger crust. The majority of veins (54 out of 65) have δ44Ca between that of seawater and basalt, which implies that they may have formed quite soon after crustal formation before other sources of calcium became available. We conclude that calcium carbonate vein formation may derive a significant fraction of calcium from seafloor alteration of basalts. This may cause rates of carbonate vein formation to be sensitive to aspects of ocean chemistry that vary due to changing climate conditions.

Clonorcis sinensis eggs are associated with calcium carbonate gallbladder stones.

PubMed

Qiao, Tie; Ma, Rui-hong; Luo, Zhen-liang; Yang, Liu-qing; Luo, Xiao-bing; Zheng, Pei-ming

2014-10-01

Calcium carbonate gallbladder stones were easily neglected because they were previously reported as a rare stone type in adults. The aim of this study was to investigate the relationship between calcium carbonate stones and Clonorchis sinensis infection. A total of 598 gallbladder stones were studied. The stone types were identified by FTIR spectroscopy. The C. sinensis eggs and DNA were detected by microscopic examination and real-time fluorescent PCR respectively. And then, some egg-positive stones were randomly selected for further SEM examination. Corresponding clinical characteristics of patients with different types of stones were also statistically analyzed. The detection rate of C. sinensis eggs in calcium carbonate stone, pigment stone, mixed stone and cholesterol stone types, as well as other stone types was 60%, 44%, 36%, 6% and 30%, respectively, which was highest in calcium carbonate stone yet lowest in cholesterol stone. A total of 182 stones were egg-positive, 67 (37%) of which were calcium carbonate stones. The C. sinensis eggs were found adherent to calcium carbonate crystals by both light microscopy and scanning electron microscopy. Patients with calcium carbonate stones were mainly male between the ages of 30 and 60, the CO2 combining power of patients with calcium carbonate stones were higher than those with cholesterol stones. Calcium carbonate gallbladder stones are not rare, the formation of which may be associated with C. sinensis infection. Copyright © 2014 Elsevier B.V. All rights reserved.

Some investigations of the deposition of travertine from Hot Springs-I. The isotopic chemistry of a travertine-depositing spring

USGS Publications Warehouse

Friedman, I.

1970-01-01

The isotopic compositions of the travertine and of the hot spring solutions were studied at Main Springs and New Highland Terrace in the Mammoth Hot Springs area of Yellowstone Park. The springs issue at 74??C and a pH of 6.65 and the carbon isotopic composition of the travertine depositing at the orifice is +2%.??C13 (PDB). As the water travels out from the orifice, it cools and loses CO2. The travertine depositing at lower temperature is enriched in C13, reaching values of +4.8%. and the solution has a pH of 8.2 at 27??C. The ??C13 of the carbon species in solution is about -2.3%. at 74?? and about +4.3 at 27??C. Therefore, the difference in ??C13 between the solid and solution is approximately 4%. at 74?? and decreases to zero at about 20??C. These differences are shown to be due to kinetic (non-equilibrium) factors. The ??O18 contents of the travertine and water show that in most samples the carbonate oxygen is in equilibrium with the water O18 at the temperatures of deposition. This is especially true for travertine depositing slowly and at temperatures above about 50??C. Calculations based on pH and alkalinity titrations of the hot spring waters in situ show that at the spring orifice the water is very high in free CO2, which is quickly lost in transit. The springs are supersaturated with respect to both aragonite and calcite during most of their travel in the open air. The carbon isotopic composition of the travertine is similar to that in the marine carbonates that are adjacent to the springs and that are the probable source of the calcium carbonate. The travertine from inactive prehistoric springs near Mammoth has similar ??C13 and O18 to that from the active springs. Soda Butte, an inactive center 25 miles east of Mammoth, contains heavier carbon and oxygen than the springs near Mammoth. ?? 1970.

Effect of substrate nature on the electrochemical deposition of calcium-deficient hydroxyapatites

NASA Astrophysics Data System (ADS)

Gualdrón-Reyes, A. F.; Domínguez-Vélez, V.; Morales-Morales, J. A.; Cabanzo, R.; Meléndez, A. M.

2017-01-01

Calcium phosphates were obtained by reducing nitrate ions to produce hydroxide ions on TiO2/stainless steel and TiO2/titanium electrodes. TiO2 coatings on metallic substrates were prepared by sol-gel dip-coating method. The morphology of deposits was observed by FESEM. Chemical nature of calcium phosphate deposits was identified by Raman micro-spectroscopy and FESEM/EDS microanalysis. Electrochemical behavior of nitrate and nitrite reduction on stainless steel and titanium electrodes was studied by linear sweep voltammetry. In addition, voltammetric study of the calcium phosphate electrodeposition on both electrodes was performed. From these measurements was selected the potential to form a calcium phosphate. A catalytic current associated to nitrate reduction reaction was obtained for stainless steel electrode, leading to significant deposition of calcium phosphate. Ca/P ratio for both substrates was less than 1.67. The formation of calcium deficient hydroxyapatite was confirmed by Raman spectroscopy.

[Effects of long-term fertilization on pH buffer system of sandy loam calcareous fluvor-aquic soil].

PubMed

Wang, Ji-Dong; Qi, Bing-Jie; Zhang, Yong-Chun; Zhang, Ai-Jun; Ning, Yun-Wang; Xu, Xian-Ju; Zhang, Hui; Ma, Hong-Bo

2012-04-01

Soil samples (0-80 cm) were collected from a 30-year fertilization experimental site in Xuzhou, Jiangsu Province of East China to study the variations of the pH, calcium carbonate and active calcium carbonate contents, and pH buffer capacity of sandy loam calcareous fluvor-aquic soil under different fertilization treatments. Thirty-year continuous application of different fertilizers accelerated the acidification of topsoil (0-20 cm), with the soil pH decreased by 0.41-0.70. Under different fertilization, the soil pH buffer capacity (pHBC) varied from 15.82 to 21.96 cmol x kg(-1). As compared with no fertilization, single N fertilization decreased the pHBC significantly, but N fertilization combined with organic fertilization could significantly increase the pHBC. The soil pHBC had significant positive correlations with soil calcium carbonate and active calcium carbonate contents, but less correlation with soil organic matter content and soil cation exchange capacity, suggesting that after a long-term fertilization, the sandy loam calcareous fluvor-aquic soil was still of an elementary calcium carbonate buffer system, and soil organic matter and cation exchange capacity contributed little to the buffer system. The soil calcium carbonate and active calcium carbonate contents were greater in 0-40 cm than in 40-80 cm soil layer. Comparing with soil calcium carbonate, soil active calcium carbonate was more sensitive to reflect the changes of soil physical and chemical properties, suggesting that the calcium carbonate buffer system could be further classified as soil active calcium carbonate buffer system.

Reconnaissance investigation of high-calcium marble in the Beaver Creek area, St. Lawrence County, New York

USGS Publications Warehouse

Brown, C. Ervin

1978-01-01

Three belts of marble of the Grenville Series were mapped in the Beaver Creek drainage basin, St. Lawrence County, N.Y. One of these, on the west side of Beaver Creek, consists of coarsely crystalline pure calcitic marble that occurs in a zone at least 10 by 0.8 km in extent. Samples of marble show CaCO3 content to be greater than 93 percent, and some samples contain greater than 96 percent, and only small amounts of MgO and Fe203 are present. Marble in two other belts to the east of Beaver Creek are variable in composition, but locally have high content of calcium carbonate material. The marble deposit west of Beaver Creek has a chemical composition favorable for specialized chemical, industrial, and metallurgical uses. Another favorable aspect of the deposit is its proximity to inexpensive water transportation on the St. Lawrence Seaway only 27.5 km away by road, at Ogdensburg, N.Y.

Nacre-like calcium carbonate controlled by ionic liquid/graphene oxide composite template.

PubMed

Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying

2015-06-01

Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Transglutaminase-induced crosslinking of gelatin-calcium carbonate composite films.

PubMed

Wang, Yuemeng; Liu, Anjun; Ye, Ran; Wang, Wenhang; Li, Xin

2015-01-01

The effects of transglutaminase (TGase) on the rheological profiles and interactions of gelatin-calcium carbonate solutions were studied. In addition, mechanical properties, water vapour permeability and microstructures of gelatin-calcium carbonate films were also investigated and compared. Fluorescence data suggested that the interaction of TGase and gelation-calcium carbonate belonged to a static quenching mechanism, and merely one binding site between TGase and gelatin-calcium carbonate was identified. Moreover, differential scanning calorimetry (DSC), the mechanical properties and the water vapour permeability studies revealed that TGase favoured the strong intramolecular polymerisation of the peptides in gelatin. The microstructures of the surfaces and cross sections in gelatin-calcium carbonate films were shown by scanning electron microscope (SEM) micrographs. The results of the fourier transform infrared spectroscopy (FTIR) indicated that TGase caused conformational changes in the proteins films. Therefore, TGase successfully facilitated the formation of gelatin-calcium carbonate composite films. Copyright © 2014 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Recker, R.R.

Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/-more » 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement.« less

Soil bacterial communities of a calcium-supplemented and a reference watershed at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA

Treesearch

Ganapathi Sridevi; Rakesh Minocha; Swathi A. Turlapati; Katherine C. Goldfarb; Eoin L. Brodie; Louis S. Tisa; Subhash C. Minocha

2012-01-01

Soil Ca depletion because of acidic deposition-related soil chemistry changes has led to the decline of forest productivity and carbon sequestration in the northeastern USA. In 1999, acidic watershed (WS) 1 at the Hubbard Brook Experimental Forest (HBEF), NH, USA was amended with Ca silicate to restore soil Ca pools. In 2006, soil samples were collected from the Ca-...

Granule fraction inhomogeneity of calcium carbonate/sorbitol in roller compacted granules.

PubMed

Bacher, C; Olsen, P M; Bertelsen, P; Sonnergaard, J M

2008-02-12

The granule fraction inhomogeneity of roller compacted granules was examined on mixtures of three different morphologic forms of calcium carbonate and three particle sizes of sorbitol. The granule fraction inhomogeneity was determined by the distribution of the calcium carbonate in each of the 10 size fractions between 0 and 2000 microm and by calculating the demixing potential. Significant inhomogeneous occurrence of calcium carbonate in the size fractions was demonstrated, depending mostly on the particles sizes of sorbitol but also on the morphological forms of calcium carbonate. The heterogeneous distribution of calcium carbonate was related to the decrease in compactibility of roller compacted granules in comparison to the ungranulated materials. This phenomenon was explained by a mechanism where fracturing of the ribbon during granulation occurred at the weakest interparticulate bonds (the calcium carbonate: calcium carbonate bonds) and consequently exposed the weakest areas of bond formation on the surface of the granules. Accordingly, the non-uniform allocation of the interparticulate attractive forces in a tablet would cause a lowering of the compactibility. Furthermore, the ability of the powder to agglomerate in the roller compactor was demonstrated to be related to the ability of the powder to be compacted into a tablet, thus the most compactable calcium carbonate and the smallest sized sorbitol improved the homogeneity by decreasing the demixing potential.

Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.

2010-01-12

Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain atmore » a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.« less

Testing Urey's carbonate-silicate cycle using the calcium isotopic composition of sedimentary carbonates

NASA Astrophysics Data System (ADS)

Blättler, Clara L.; Higgins, John A.

2017-12-01

Carbonate minerals constitute a major component of the sedimentary geological record and an archive of a fraction of the carbon and calcium cycled through the Earth's surface reservoirs for over three billion years. For calcium, carbonate minerals constitute the ultimate sink for almost all calcium liberated during continental and submarine weathering of silicate minerals. This study presents >500 stable isotope ratios of calcium in Precambrian carbonate sediments, both limestones and dolomites, in an attempt to characterize the isotope mass balance of the sedimentary carbonate reservoir through time. The mean of the dataset is indistinguishable from estimates of the calcium isotope ratio of bulk silicate Earth, consistent with the Urey cycle being the dominant mechanism exchanging calcium among surface reservoirs. The variability in bulk sediment calcium isotope ratios within each geological unit does not reflect changes in the global calcium cycle, but rather highlights the importance of local mineralogical and/or diagenetic effects in the carbonate record. This dataset demonstrates the potential for calcium isotope ratios to help assess these local effects, such as the former presence of aragonite, even in rocks with a history of neomorphism and recrystallization. Additionally, 29 calcium isotope measurements are presented from ODP (Ocean Drilling Program) Site 801 that contribute to the characterization of altered oceanic crust as an additional sink for calcium, and whose distinct isotopic signature places a limit on the importance of this subduction flux over Earth history.

Serum 1,25-dihydroxyvitamin D and calcium intake affect rates of bone calcium deposition during pregnancy and the early postpartum period123

PubMed Central

O'Brien, Kimberly O; Donangelo, Carmen M; Ritchie, Lorrene D; Gildengorin, Ginny; Abrams, Steve

2012-01-01

Background: Factors affecting bone calcium deposition across pregnancy and lactation are not well characterized. Objective: The impact of maternal age, calcium intake, race-ethnicity, and vitamin D status on the rate of bone calcium deposition (VO+) was assessed across pregnancy and lactation. Design: Stable calcium isotopes were given to 46 women at pre- or early pregnancy (trimester 1), late pregnancy (trimester 3), and 3–10 wk postpartum. Three cohorts were included: 23 adolescents from Baltimore (MD), aged 16.5 ± 1.4 y (mean ± SD; Baltimore cohort); 13 adults from California, aged 29.5 ± 2.6 y (California cohort); and 10 adults from Brazil, aged 30.4 ± 4.0 y (Brazil cohort). The total exchangeable calcium pool, VO+, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D [1,25(OH)2D], parathyroid hormone, and calcium intake were evaluated. Results: At trimester 3, inverse associations between 1,25(OH)2D and VO+ were evident in the Baltimore (P = 0.059) and Brazil (P = 0.008) cohorts and in the whole group (P = 0.029); calcium intake was not a significant determinant of VO+ in any group during pregnancy. At postpartum, a significant positive association was evident between VO+ and calcium intake (P ≤ 0.002) and between VO+ and African ethnicity (P ≤ 0.004) in the whole group and within the Baltimore and Brazil cohorts. Conclusions: Elevated 1,25(OH)2D was associated with decreased rates of bone calcium deposition during late pregnancy, a finding that was particularly evident in pregnant adolescents and adult women with low calcium intakes. Higher dietary calcium intakes and African ethnicity were associated with elevated rates of bone calcium deposition in the postpartum period. PMID:22648718

Repeated occurrences of methanogenic zones, diagenetic dolomite formation and linked silicate alteration in southern Bering Sea sediments (Bowers Ridge, IODP Exp. 323 Site U1341)

NASA Astrophysics Data System (ADS)

Wehrmann, L. M.; Ockert, C.; Mix, A. C.; Gussone, N.; Teichert, B. M. A.; Meister, P.

2016-03-01

Diagenetic precipitates, such as dolomite, and the chemistry of residual deeply buried porewater often represent the only traces of past biogeochemical activity in marine sediments. A 600 m thick sedimentary section, recently drilled at Integrated Ocean Drilling Program (IODP) Site U1341 on Bowers Ridge (southern Bering Sea), provides insight into such a 4.3 Ma old paleo-diagenetic archive. Hard-lithified calcite-dolomite layers, and laminae of disseminated carbonate, were recovered in diatom-rich sediments over a depth range of 400 m. Carbon isotope values of the diagenetic carbonates between -16.6 and -14.4‰ (VPDB) and strontium isotope ratios of dolomites close to past seawater values suggest carbonate precipitation induced by the production of dissolved inorganic carbon (DIC) during elevated rates of organic carbon mineralization, primarily via sulfate reduction, at shallow sediment depth below the paleo-seafloor. Diagenetic carbonates at 280-440 m below seafloor were likely also produced by the intermittent onset of sulfate reduction coupled to the anaerobic oxidation of methane (AOM) at sulfate-methane transition zones (SMTZ). These microbially mediated processes do not occur in the sediment at this site at present but were likely connected to the presence of a methanogenic zone at 2.58-2.51 Ma. A minimum in sulfate concentrations in modern porewaters and low sedimentary Ba/Al ratios resulting from former sulfate depletion are reminiscent of the presence of this large methanogenic zone. The minimum in sulfate concentrations is reflected in a minimum in magnesium concentrations, less radiogenic strontium and isotopically light calcium in the porewater. It is proposed that magnesium was removed from the porewater during carbonate precipitation and volcanic ash alteration which occurred in the former methanogenic zone and also released strontium with a less radiogenic isotope ratio and isotopically light calcium into the porewater. The isotopic composition of porewater calcium was also influenced by ammonium-calcium exchange on clay minerals and carbonate recrystallization. Our study elucidates the response of porewater element concentrations and isotopic profiles interlinked with the formation of diagenetic carbonates to changes in the deposition of organic carbon in sediments of deeper water sites (>2000 m water depth) over prolonged timescales. It shows that variations in biogeochemical processes in response to changes in oceanographic conditions and a dynamic subseafloor biogeochemical zonation have to also be taken into account at these deep water sites for a global assessment of organic carbon burial fluxes and remineralization.

Chemical composition of bulk precipitation in the North-Central and Northeastern United States, December 1980 through February 1981

USGS Publications Warehouse

Peters, Norman E.; Bonelli, Joseph E.

1982-01-01

Samples of bulk precipitation were collected at 179 sites in the North-Central and Northeastern United States for 3 months during winter 1980-81 to provide data on the distribution of chemical constituents. Concentrations and average daily loads of 29 dissolved constituents were determined. Sodium and chloride deposition was relatively high in coastal areas and adjacent to some urban centers. Regional patterns of to daily loads of hydrogen ion, nitrate, lead, and iron correlate well with one another and form a concentric pattern around the center of high deposition in eastern Ohio and western Pennsylvania, suggesting an urban-industrial source. Samples from this area had low pH (5.7). The latter samples had high concentrations of calcium and total inorganic carbon, suggesting pH control by soil-derived carbonate minerals. Deposition patterns of ammonium, nitrate, and sulfate display regional highs in Illinois, Indiana, and southwestern Michigan, suggesting agricultural sources such as fertilizer. Median loads of zinc, iron, and lead were lower than reported in previous studies for North America. The apparent decrease in lead since 1950 throughout the area is attributed to reduced consumption of leaded fuels and lower deposition in winter.

Calcium carbonate nucleation in an alkaline lake surface water, Pyramid Lake, Nevada, USA

USGS Publications Warehouse

Reddy, Michael M.; Hoch, Anthony

2012-01-01

Calcium concentration and calcite supersaturation (Ω) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has Ω values of 10-16. Notwithstanding high Ω, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean Ω at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water Ω. Calcium concentration and Ω regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower Ω than filtered samples. Calcium concentration and Ω at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (Ω) + B. The best fit rate equation "Rate (Δ mM/Δ min) = -0.0026 Ω + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, Ω at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors.

Calcium Carbonate Nucleation in an Alkaline Lake Surface Water, Pyramid Lake, Nevada, USA

USGS Publications Warehouse

Reddy, M.M.; Hoch, A.

2012-01-01

Calcium concentration and calcite supersaturation (??) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has ?? values of 10-16. Notwithstanding high ??, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean ?? at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water ??. Calcium concentration and ?? regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower ?? than filtered samples. Calcium concentration and ?? at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (??) + B. The best fit rate equation "Rate (?? mM/?? min) = -0.0026 ?? + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, ?? at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors. ?? 2011 U.S. Government.

The enzyme carbonic anhydrase as an integral component of biogenic Ca-carbonate formation in sponge spicules☆

PubMed Central

Müller, Werner E.G.; Schröder, Heinz C.; Schlossmacher, Ute; Neufurth, Meik; Geurtsen, Werner; Korzhev, Michael; Wang, Xiaohong

2013-01-01

The inorganic scaffold of the spicules, the skeletal elements of the calcareous sponges, is formed of calcium carbonate (CaCO3). The growth of the approximately 300-μm large spicules, such as those of the calcareous sponge Sycon raphanus used in the present study, is a rapid process with a rate of about 65 μm/h. The formation of CaCO3 is predominantly carried out by the enzyme carbonic anhydrase (CA). The enzyme from the sponge S. raphanus was isolated and prepared by recombination. The CA-driven deposition of CaCO3 crystallites is dependent on temperature (optimal at 52 °C), the pH value of the reaction assay (7.5/8.0), and the substrate concentration (CO2 and Ca2+). During the initial phase of crystallite formation, ≈40 μm large round-shaped deposits are formed that remodel to larger prisms. These crystal-like prisms associate to each other and form either rope-/bundle-like aggregates or arrange perfectly with their smaller planes along opposing surfaces of the sponge spicule rays. The CA-dependent CaCO3 deposition can be inhibited by the CA-specific inhibitor acetazolamide. The Michaelis–Menten constant for the CA-driven mineralization has been determined to be around 8 mM with respect to CaCO3. The deposits formed have a Martens hardness of ≈5 GPa. The data presented here highlights for the first time that calcite deposition in the sponge system is decisively controlled enzymatically. This data will contribute to the development of new strategies applicable for the fabrication of novel biomaterials. PMID:24251096

The preparation and performance of calcium carbide-derived carbon/polyaniline composite electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Zheng, Liping; Wang, Ying; Wang, Xianyou; Li, Na; An, Hongfang; Chen, Huajie; Guo, Jia

Calcium carbide (CaC 2)-derived carbon (CCDC)/polyaniline (PANI) composite materials are prepared by in situ chemical oxidation polymerization of an aniline solution containing well-dispersed CCDC. The structure and morphology of CCDC/PANI composite are characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N 2 sorption isotherms. It has been found that PANI was uniformly deposited on the surface and the inner pores of CCDC. The supercapacitive behaviors of the CCDC/PANI composite materials are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results show that the CCDC/PANI composite electrodes have higher specific capacitances than the as grown CCDC electrodes and higher stability than the conducting polymers. The capacitance of CCDC/PANI composite electrode is as high as 713.4 F g -1 measured by cyclic voltammetry at 1 mV s -1. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles.

Applying a biodeposition layer to increase the bond of a repair mortar on a mortar substrate.

PubMed

Snoeck, D; Wang, J; Bentz, D P; De Belie, N

2018-02-01

One of the major concerns in infrastructure repair is a sufficient bond between the substrate and the repair material, especially for the long-term performance and durability of the repaired structure. In this study, the bond of the repair material on the mortar substrate is promoted via the biodeposition of a calcium carbonate layer by a ureolytic bacterium. X-ray diffraction and scanning electron microscopy were used to examine the interfaces between the repair material and the substrate, as well as the polymorph of the deposited calcium carbonate. The approximately 50 μm thick biodeposition film on the mortar surface mostly consisted of calcite and vaterite. Both the repair material and the substrate tended to show a good adherence to that layer. The bond, as assessed by slant shear specimen testing, was improved by the presence of the biodeposition layer. A further increase was found when engineering the substrate surface using a structured pattern layer of biodeposition.

Calcic soils and calcretes in the southwestern United States

USGS Publications Warehouse

Bachman, George Odell; Machette, Michael N.

1977-01-01

Secondary calcium carbonate of diverse origins, 'caliche' of many authors, is widespread in the southwestern United States. 'Caliche' includes various carbonates such as calcic soils and products of groundwater cementation. The term 'caliche' is generally avoided in this report in favor of such terms as calcrete, calcic soils, and pervasively cemented deposits. Criteria for the recognition of various types of calcrete of diverse origins include field relations and laboratory data. Calcic soils provide a comprehensive set of characteristics that aid in their recognition in the field. These characteristics include a distinctive morphology that is zoned horizontally and can frequently be traced over tens to hundreds of square kilometers. The major process in the formation of pedogenic calcrete and calic soils is the leaching of calcium carbonate from upper soil horizons by downward percolating soil solutions and reprecipitation of the carbonate in alluvial horizons near the base of the soil profile. The formation of pedogenic calcrete involves many factors including climate, source of carbonate, and tectonic stability of the geomorphic surface on which the calcrete is deposited. Most of the carbonate in pedogenic calcrete is probably derived from windblown sand, dust, and rain. Calcic soils and pedogenic calcretes follow a six-stage sequence morphologic development and is based on a classification devised by Gile, Peterson and Grossman in 1966. The .six morphologic stages of carbonate deposition in soils are related to the relative age of the soil and are as follows: I. The first or youngest stage includes filamentous or faint coatings of carbonate on detrital grains. II. The second stage includes pebble coatings which are continuous; firm carbonate nodules are few to common. III. The third stage includes coalesced nodules which occur in a friable or disseminated carbonate matrix. IV. The fourth stage includes platy, firmly cemented matrix which engulfs nodules; horizon is plugged to downward moving solutions. V. The fifth stage includes soils which are platy to tabular, dense, strongly cemented. A well-developed laminar layer occurs on the upper surface. VI. The sixth and most advanced stage is massive, multilaminar, and strongly cemented calcrete with abundant pisoliths, the upper surface of which may be brecciated. Pisoliths may indicate many generations of brecciation and reformation. In general calcic soils include stages I through III and are friable to moderately indurated; whereas pedogenic calcretes include stages IV through VI and are dense and strongly indurated. In a single pedon the morphologic stage of carbonate deposition decreases downward in the profile. The stage of development may be used in local regions for correlation and determination of relative ages of soils and geomorphic surfaces. Some structures observed in pedogenic calcretes may be present in other types of calcrete but the horizontal zonation typical of deposits of soil processes is absent. Laminar structure in particular is not restricted to pedogenic deposits and is common in many varieties of calcrete. Very little chemical change occurs in the noncalcareous nonclayey fractions of calcretes with age; but clay minerals within calcretes undergo a complex history of authigenesis. There is a depletion of magnesium in the calcareous portion and an enrichment of magnesium in the clayey portion of a calcrete with age. In keeping with this relationship, montmorillonite, or mixed layer montmorillonite-illite, is common in younger calcretes; whereas the high magnesium-silicate clays, sepiolite and palygorskite, are common in older calcretes. This indicates that the magnesium depleted from the carbonate is redistributed authigenically in clay minerals. The mobility of carbonate introduces many problems in attempts to date calcretes directly. Although the relative ages of soils within a province may be determined by quant

Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

USGS Publications Warehouse

Leenheer, Jerry A.; Reddy, Michael M.

2008-01-01

Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

Calcium carbonate does not affect imatinib pharmacokinetics in healthy volunteers.

PubMed

Tawbi, Hussein; Christner, Susan M; Lin, Yan; Johnson, Matthew; Mowrey, Emily T; Cherrin, Craig; Chu, Edward; Lee, James J; Puhalla, Shannon; Stoller, Ronald; Appleman, Leonard R; Miller, Brian M; Beumer, Jan H

2014-01-01

Imatinib mesylate (Gleevec(®)/Glivec(®)) has revolutionized the treatment of chronic myeloid leukemias and gastrointestinal stromal tumors, and there is evidence for an exposure response relationship. Calcium carbonate is increasingly used as a calcium supplement and in the setting of gastric upset associated with imatinib therapy. Calcium carbonate could conceivably elevate gastric pH and complex imatinib, thereby influencing imatinib absorption and exposure. We aimed to evaluate whether use of calcium carbonate has a significant effect on imatinib pharmacokinetics. Eleven healthy subjects were enrolled in a 2-period, open-label, single-institution, randomized crossover, fixed-schedule study. In one period, each subject received 400 mg of imatinib p.o. In the other period, 4,000 mg calcium carbonate (Tums Ultra(®)) was administered p.o. 15 min before 400 mg of imatinib. Plasma concentrations of imatinib and its active N-desmethyl metabolite CGP74588 were assayed by LC-MS; data were analyzed non-compartmentally and compared after log transformation. Calcium carbonate administration did not significantly affect the imatinib area under the plasma concentration versus time curve (AUC) (41.2 μg/mL h alone vs. 40.8 μg/mL h with calcium carbonate, P = 0.99), maximum plasma concentration (C(max)) (2.35 μg/mL alone vs. 2.39 μg/mL with calcium carbonate, P = 0.89). Our results indicate that the use of calcium carbonate does not significantly affect imatinib pharmacokinetics.

Calcium carbonate with magnesium overdose

MedlinePlus

The combination of calcium carbonate and magnesium is commonly found in antacids. These medicines provide heartburn relief. Calcium carbonate with magnesium overdose occurs when someone takes more than the ...

Iodine-to-calcium ratios in carbonates suggest a primary origin for the Precambrian Lomagundi and Shuram carbon isotope excursions

NASA Astrophysics Data System (ADS)

Hardisty, D. S.; Lu, Z.; Planavsky, N. J.; Osburn, M. R.; Bekker, A.; Lyons, T. W.

2013-12-01

Systematic increases in iodine-to-calcium ratios (I/Ca) in carbonates from both the Precambrian Lomagundi and Shuram carbonate carbon isotope (δ13Ccarb) excursion intervals suggest primary origins for these events. Iodate (IO3-), the oxidized iodine species, is the exclusive species incorporated into carbonates. The high redox sensitivity of IO3- to deoxygenation requires highly oxidizing fluids for IO3- production, making I/Ca in platform carbonates a simple indicator of the presence of oxidizing fluids in the surface ocean. Similarly, redox sensitivity makes the proxy host susceptible to diagenetic iodine loss during carbonate recrystallization in reducing pore fluids. Recent work has shown carbonates to experience near-complete iodine loss during dolomitization in the Permian, and work from our group evaluating modern and recent carbonates demonstrate the potential for diagenetic iodine loss during carbonate recrystallization. In some cases, however, such as meteoric aragonite-to-calcite transitions, oxidizing pore fluids have the potential to buffer IO3- concentrations, causing negligible alteration to primary I/Ca despite negative shifts in δ13Ccarb. These results highlight that diagenetic alterations to I/Ca and δ13Ccarb need not always be coupled, but importantly, no observed scenario promotes post-depositional addition of iodine to carbonates. This means that, independent of δ13Ccarb, systematic, stratigraphic increases in I/Ca ratios observed in the carbonate record are most easily interpreted as resulting from depositional controls such as surface ocean redox or shifts in the total marine iodine reservoir. From this, increasing I/Ca ratios coincident with rising and falling δ13Ccarb trends for the Paleoproterozic Lomagundi and Neoproterozoic Shuram events, respectively, support suggestions of a primary origin for the δ13Ccarb excursions. Significant increase in I/Ca in dolomites deposited during the Lomagundi excursion, rising from blank values in the Archean, suggest very early dolomitization in an oxidizing surface ocean promoting aerobic iodine cycling. This interpretation is consistent with earlier suggestions relating a >+10 ‰ δ13Ccarb shift to substantial organic carbon burial and associated oxygen production. Extremely negative δ13Ccarb (down to <-10 ‰) observed during the Shuram event have been linked to both diagenetic and primary mechanisms. We propose, however, that a marked increase in I/Ca ratios associated with the negative δ13Ccarb excursion in the Khufai Formation of Oman provides evidence for a primary origin for the Shuram. Such an increase could be interpreted as enhanced delivery of IO3- or total iodine from the deep ocean, perhaps driven by deep ocean ventilation and/or oxidation of a large pool of marine-derived organic matter. Overall, regardless of the individual primary controls driving increases in carbonate I/Ca during the Lomagundi and Shuram events, authigenic/diagenetic controls allowing for increased I/Ca are unlikely, suggesting a primary origin for the two largest δ13Ccarb excursions in Earth history.

Investigating the Basis of Biogenic Calcium Carbonate Formation from an Amorphous Precursor: Nature of the Transformation to Calcite on Hydroxyl Functionalized Surfaces

NASA Astrophysics Data System (ADS)

Wang, D.; Lee, J. R.; Talley, C. E.; Murphy, K. E.; Han, T. Y.; Deyoreo, J. J.; Dove, P. M.

2006-12-01

Calcium carbonate biominerals are particularly significant because of their direct role in regulating the global carbon cycle, as well as their ubiquitous occurrence across earth environments. Biogenic carbonates are further distinguished by their broad phlyogenetic distribution; hence it has been suggested that unrelated eukaryotes must have used similar biochemical strategies to control mineralization. Recent studies have shown that an amorphous calcium carbonate (ACC) phase potentially plays a key role in the initial formation of carbonate minerals and in "shaping" them into complex morphologies widely seen in biominerals. Echinoderms, mollusks, and possibly many other organisms use ACC as a precursor phase that is first nucleated in cellularly controlled environments such as vesicles and subsequently transforms into a fully crystalline material. Recent studies on sea urchin embryos have shown that during transformation ACC develops short range that resembles calcite before fully crystallizing and serve as inspiration for our studies in synthetic systems. Self-assembled monolayers (SAM) on gold and silver have been used as simple model systems that approximate biological surfaces. Many studies have shown that thiol monolayers with hydroxyl termination stabilize a transitory ACC film that with prolonged exposure to aqueous solution transforms into calcite nucleated on {104} faces. Using Near Edge X-ray Absorption Fine Structure (NEXAFS) we studied SAM/mineral interactions with well ordered mercaptophenol monolayers showed that when these films are first exposed to calcium carbonate solutions, they become disordered and remain so after subsequent deposition of an ACC over-layer. Yet calcite nucleates and grows from the surface bound ACC with predominantly {104} orientation, which suggests a dynamic structural relationship between the SAMs and the mineral phase. While the monolayer/mineral phase interaction has been characterized, the mechanism for nucleating calcite from ACC on these SAMs remains unknown and is the objective of this research. Our preliminary observations of the transforming ACC film with in situ Raman spectroscopy have shown a strengthening of the symmetric mode of the carbonate ion suggesting ordering of the ACC. To fully determine the structural evolution of the mineral phase we will use both Raman and Extended X-Ray Absorption Fine Structure (EXAFS) measurements, coupled with morphological analysis using SEM.

Risk factors for calcium carbonate urolithiasis in goats.

PubMed

Nwaokorie, Eugene E; Osborne, Carl A; Lulich, Jody P; Fletcher, Thomas F; Ulrich, Lisa K; Koehler, Lori A; Buettner, Michelle T

2015-08-01

To identify demographic or signalment factors associated with calcium carbonate urolith formation in goats. Retrospective case series and case-control study. 354 goats with calcium carbonate uroliths (case animals) and 16,366 goats without urinary tract disease (control animals). Medical records of the Minnesota Urolith Center were reviewed to identify case goats for which samples were submitted between January 1, 1984, and December 31, 2012. Control goats evaluated at US veterinary teaching hospitals in the same time period were identified by searching Veterinary Medical Database records. Age, breed, sex, reproductive status, geographic location, season, and anatomic location of collected uroliths were analyzed to identify risk or protective factors associated with calcium carbonate urolithiasis. Nigerian dwarf goats had higher odds of developing calcium carbonate uroliths than did Pygmy goats (reference group). Several breeds had lower odds of this finding, compared with Pygmy goats; odds were lowest for mixed, Anglo-Nubian, and Toggenburg breeds. Breeds of African origin (Pygmy, Nigerian Dwarf, and Boer) comprised 146 of 275 (53%) case goats with data available. Goats of African descent had a higher risk of developing calcium carbonate uroliths than did goats of non-African descent (reference group). Males and neutered goats had higher odds of calcium carbonate urolithiasis, compared with females and sexually intact goats, respectively. Age category, geographic location, and season were associated with detection of calcium carbonate uroliths. Goats with calcium carbonate uroliths were typically neutered males, > 1 year of age, and of African descent. This study identified factors associated with calcium carbonate urolithiasis in goats; however, these associations do not allow conclusions regarding cause-and-effect relationships.

Assessment of the Potential Role of Streptomyces in Cave Moonmilk Formation

PubMed Central

Maciejewska, Marta; Adam, Delphine; Naômé, Aymeric; Martinet, Loïc; Tenconi, Elodie; Całusińska, Magdalena; Delfosse, Philippe; Hanikenne, Marc; Baurain, Denis; Compère, Philippe; Carnol, Monique; Barton, Hazel A.; Rigali, Sébastien

2017-01-01

Moonmilk is a karstic speleothem mainly composed of fine calcium carbonate crystals (CaCO3) with different textures ranging from pasty to hard, in which the contribution of biotic rock-building processes is presumed to involve indigenous microorganisms. The real microbial input in the genesis of moonmilk is difficult to assess leading to controversial hypotheses explaining the origins and the mechanisms (biotic vs. abiotic) involved. In this work, we undertook a comprehensive approach in order to assess the potential role of filamentous bacteria, particularly a collection of moonmilk-originating Streptomyces, in the genesis of this speleothem. Scanning electron microscopy (SEM) confirmed that indigenous filamentous bacteria could indeed participate in moonmilk development by serving as nucleation sites for CaCO3 deposition. The metabolic activities involved in CaCO3 transformation were furthermore assessed in vitro among the collection of moonmilk Streptomyces, which revealed that peptides/amino acids ammonification, and to a lesser extend ureolysis, could be privileged metabolic pathways participating in carbonate precipitation by increasing the pH of the bacterial environment. Additionally, in silico search for the genes involved in biomineralization processes including ureolysis, dissimilatory nitrate reduction to ammonia, active calcium ion transport, and reversible hydration of CO2 allowed to identify genetic predispositions for carbonate precipitation in Streptomyces. Finally, their biomineralization abilities were confirmed by environmental SEM, which allowed to visualize the formation of abundant mineral deposits under laboratory conditions. Overall, our study provides novel evidences that filamentous Actinobacteria could be key protagonists in the genesis of moonmilk through a wide spectrum of biomineralization processes. PMID:28706508

In-vitro analysis of early calcification in aortic valvular interstitial cells using Laser-Induced Breakdown Spectroscopy (LIBS).

PubMed

Davari, Seyyed Ali; Masjedi, Shirin; Ferdous, Zannatul; Mukherjee, Dibyendu

2018-01-01

Calcific aortic valve disease (CAVD) is a major cardiovascular disorder caused by osteogenic differentiation of valvular interstitial cells (VICs) within aortic valves. Conventional methods like colorimetric assays and histology fail to detect small calcium depositions during in-vitro VIC cultures. Laser-induced breakdown spectroscopy (LIBS) is a robust analytical tool used for inorganic materials characterizations, but relatively new to biomedical applications. We employ LIBS, for the first time, for quantitative in-vitro detection of calcium depositions in VICs at various osteogenic differentiation stages. VICs isolated from porcine aortic valves were cultured in osteogenic media over various days. Colorimetric calcium assays based on arsenazo dye and Von Kossa staining measured the calcium depositions within VICs. Simultaneously, LIBS signatures for Ca I (422.67 nm) atomic emission lines were collected for estimating calcium depositions in lyophilized VIC samples. Our results indicate excellent linear correlation between the calcium assay and our LIBS measurements. Furthermore, unlike the assay results, the LIBS results could resolve calcium signals from cell samples with as early as 2 days of osteogenic culture. Quantitatively, the LIBS measurements establish the limit of detection for calcium content in VICs to be ∼0.17±0.04 μg which indicates a 5-fold improvement over calcium assay. Picture: Quantitative LIBS enables in-vitro analysis for early stage detection of calcium deposition within aortic valvular interstitial cells (VICs). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The role microbial sulfate reduction in the direct mediation of sedimentary authigenic carbonate precipitation

NASA Astrophysics Data System (ADS)

Turchyn, A. V.; Walker, K.; Sun, X.

2016-12-01

The majority of modern deep marine sediments are bathed in water that is undersaturated with respect to calcium carbonate. However, within marine sediments changing chemical conditions, driven largely by the microbial oxidation of organic carbon in the absence of oxygen, lead to supersaturated conditions and drive calcium carbonate precipitation. This sedimentary calcium carbonate is often called `authigenic carbonate', and is found in the form of cements and disseminated crystals within the marine sedimentary pile. As this precipitation of this calcium carbonate is microbially mediated, identifying authigenic carbonate within the geological record and understanding what information its geochemical and/or isotopic signature may hold is key for understanding its importance and what information it may contain past life. However, the modern controls on authigenic carbonate precipitation remain enigmatic because the myriad of microbially mediated reactions occurring within sediments both directly and indirectly impact the proton balance. In this submission we present data from 25 ocean sediment cores spanning the globe where we explore the deviation from the stoichiometrically predicted relationships among alkalinity, calcium and sulfate concentrations. In theory for every mol of organic carbon reduced by sulfate, two mol of alkalinity is produced, and to precipitate subsurface calcium carbonate one mol of calcium is used to consume two mol of alkalinity. We use this data with a model to explore changes in carbonate saturation state with depth below the seafloor. Alkalinity changes in the subsurface are poorly correlated with changes in calcium concentrations, however calcium concentrations are directly and tightly coupled to changes in sulfate concentrations in all studied sites. This suggests a direct role for sulfate reducing bacteria in the precipitation of subsurface carbonate cements.

21 CFR 582.5191 - Calcium carbonate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This...

21 CFR 582.5191 - Calcium carbonate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This...

21 CFR 582.5191 - Calcium carbonate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This...

21 CFR 582.5191 - Calcium carbonate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This...

21 CFR 582.1191 - Calcium carbonate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or feeding...

21 CFR 582.5191 - Calcium carbonate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This...

21 CFR 582.1191 - Calcium carbonate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or feeding...

21 CFR 582.1191 - Calcium carbonate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or feeding...

21 CFR 582.1191 - Calcium carbonate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This substance is generally recognized as safe when used in accordance with good manufacturing or feeding...

Regeneration of sulfated metal oxides and carbonates

DOEpatents

Hubble, Bill R.; Siegel, Stanley; Cunningham, Paul T.

1978-03-28

Alkali metal or alkaline earth metal carbonates such as calcium carbonate and magnesium carbonate found in dolomite or limestone are employed for removal of sulfur dioxide from combustion exhaust gases. The sulfated carbonates are regenerated to oxides through use of a solid-solid reaction, particularly calcium sulfide with calcium sulfate to form calcium oxide and sulfur dioxide gas. The regeneration is performed by contacting the sulfated material with a reductant gas such as hydrogen within an inert diluent to produce calcium sulfide in mixture with the sulfate under process conditions selected to permit the sulfide-sulfate, solid-state reaction to occur.

Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

PubMed Central

Wilson, Rosamund J; Copley, J Brian

2017-01-01

Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Findings Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Conclusion Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance. PMID:28182142

Effects of Eggshell Calcium Supplementation on Bone Mass in Postmenopausal Vietnamese Women.

PubMed

Sakai, Seigo; Hien, Vu Thi Thu; Tuyen, Le Danh; Duc, Ha Anh; Masuda, Yasunobu; Yamamoto, Shigeru

2017-01-01

Bone mass decreases along with aging, especially for women after menopause because of lower estrogen secretion together with low calcium intake. This study was conducted to study the effect of eggshell calcium supplementation on bone mass in 54 postmenopausal Vietnamese women living in a farming area about 60 km from Hanoi, Vietnam. Sets of 3 subjects matched by age, bone mass, BMI and calcium intake were divided randomly into 3 groups with 18 subjects in each group. The eggshell calcium group was administered 300 mg/d calcium from eggshell, the calcium carbonate group 300 mg/d calcium from calcium carbonate and the placebo group received no calcium supplementation. Bone mass (Speed of Sound (SOS)) was measured at the beginning (the baseline), the middle (6th month) and the end of the study (12th month) by the single blind method. SOS of the eggshell group increased significantly at 12 mo (p<0.05) and was significantly higher than that of the placebo and calcium carbonate groups at 12 mo (p<0.05). The SOS of the calcium carbonate group tended to be higher than that of the placebo group but without a significant difference (p>0.05). In conclusion, eggshell calcium was more effective in increasing bone mass than calcium carbonate in postmenopausal Vietnamese women.

Raman spectroscopic analysis of a belltower commemorative wall decoration

NASA Astrophysics Data System (ADS)

Fernandes, R. F.; de Oliveira, L. F. C.; Edwards, H. G. M.; Brooke, C. J.; Pepper, M.

2017-02-01

The Raman spectroscopic analysis of a rare wall decoration in a church belltower, depicting the initials of couples married there in circular roundels over some 230 years, since 1777, has been undertaken prior to their impending restoration. The spectral data indicate that the red pigment is exclusively haematite which has been applied to plaster which exhibits the signatures variously of calcite, gypsum, anhydrite, calcium phosphate and dolomitic limestone; evidence of amorphous carbon is attributed to the deposition of soot from candle illumination, which has been recorded in historical documentation. The presence of biosignatures attributed to carotenoids in several samples is evidence of biological colonisation and potential deterioration which requires special treatment in the restoration strategies. The blackened areas near the upper edges of the wall decoration indicate carbon deposition and organic contamination. The latest addition to the decoration accomplished in 2008 shows that haematite has been used over a calcite ground. In earlier dated specimens, the presence of limewash is evident, which has only been partially converted into calcite by aerial attack from carbon dioxide in moist conditions.

Interface Analyses Between a Case-Hardened Ingot Casting Steel and Carbon-Containing and Carbon-Free Refractories

NASA Astrophysics Data System (ADS)

Fruhstorfer, Jens; Dudczig, Steffen; Rudolph, Martin; Schmidt, Gert; Brachhold, Nora; Schöttler, Leandro; Rafaja, David; Aneziris, Christos G.

2018-06-01

Corrosion tests of carbon-free and carbon-containing refractories were performed. The carbon-free crucibles corroded, whereas the carbon-containing crucibles were negligibly attacked. On them, inclusions were attached. This study investigates melt oxygen contents, interface properties, and steel compositions with their non-metallic inclusions in order to explore the inclusion formation and deposition mechanisms. The carbon-free crucibles were based on alumina, mullite, and zirconia- and titania-doped alumina (AZT). The carbon-containing (-C) ones were alumina-C and AZT-C. Furthermore, nanoscaled carbon and alumina additives (-n) were applied in an AZT-C-n material. In the crucibles, the case-hardened steel 17CrNiMo7-6 was remelted at 1580 °C. It was observed that the melt and steel oxygen contents were higher for the tests in the carbon-free crucibles. Into these crucibles, the deoxidizing alloying elements Mn and Si diffused. Reducing contents of deoxidizing elements resulted in higher steel oxygen levels and less inclusions, mainly of the inclusion group SiO2-core-MnS-shell (2.5 to 8 μ m). These developed from smaller SiO2 nuclei. The inclusion amount in the steel was highest after remelting in AZT-C-n for 30 minutes but decreased strongly with increasing remelting time (60 minutes) due to inclusions' deposition on the refractory surface. The Ti from the AZT and the nanoadditives supported inclusion growth and deposition. Other inclusion groups were alumina and calcium aluminate inclusions. Their contents were high after remelting in carbon- or AZT-containing crucibles but generally decreased during remelting. On the AZT-C-n crucible, a dense layer formed from vitreous compositions including Al, Ca, Mg, Si, and Ti. To summarize, for reducing forming inclusion amounts, mullite is recommended as refractory material. For capturing formed inclusions, AZT-C-n showed a high potential.

Control of temperature and aqueous Mg2+/Ca2+ ratio on the (trans-)formation of ikaite

NASA Astrophysics Data System (ADS)

Purgstaller, B.; Dietzel, M.; Baldermann, A.; Mavromatis, V.

2017-11-01

The calcium carbonate hexahydrate mineral ikaite (CaCO3 ṡ 6 H2O) has been documented in aquatic environments at near-freezing temperatures. An increase of the prevailing temperature in the depositional environment, results in the transformation of natural ikaite into less soluble calcium carbonate phases occasionally leaving calcite pseudomorphs in the sediments, which are considered as an indicator for primary cold water temperatures. Detailed understanding on the physicochemical parameters controlling ikaite (trans-)formation however, such as temperature and reactive solution chemical composition, are still under debate. In order to study the formation of ikaite, we conducted precipitation experiments under controlled physicochemical conditions (pH = 8.3 ± 0.1; T = 6, 12, and 18 ± 0.1 °C) at defined aqueous molar Mg/Ca ratios. The transformation of ikaite into anhydrous calcium carbonate polymorphs was investigated in solution and at air exposure. The obtained results reveal the formation of ikaite at temperatures up to 12 °C, whereas Mg-rich amorphous calcium carbonate precipitated at 18 °C. In contact with the reactive solution ikaite transformed into aragonite at aqueous molar Mg2+/Ca2+ ratios of ≥14. In contrast, ikaite separated from the Mg-rich solution and exposed to air transformed in all cases into calcite/vaterite. The herein obtained temperature limit of ≤12 for ikaite formation is significantly higher than formerly expected and most probably caused by (i) the high saturation degree of the solution with respect to ikaite and (ii) the slow dehydration of the aqueous Ca2+ ion at low temperatures. This result questions the suitability of calcite pseudomorphs (i.e. glendonites) as a proxy for near-freezing temperatures. Moreover, our findings show that the CaCO3 polymorph formed from ikaite is strongly controlled by the physicochemical conditions, such as aqueous molar Mg2+/Ca2+ ratio of the reactive fluid and H2O availability throughout the transformation process.

Protein-Mediated Precipitation of Calcium Carbonate

PubMed Central

Polowczyk, Izabela; Bastrzyk, Anna; Fiedot, Marta

2016-01-01

Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO3 particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO3 formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein. PMID:28774065

Aluminum hydroxide, calcium carbonate and calcium acetate in chronic intermittent hemodialysis patients.

PubMed

Janssen, M J; van der Kuy, A; ter Wee, P M; van Boven, W P

1996-02-01

Prevention of secondary hyperparathyroidism in uremia necessitates correction of hyperphosphatemia and hypocalcemia. In order to avoid aluminum toxicity, calcium containing phosphate binders are used increasingly, instead of aluminium hydroxide. Recent studies have shown that calcium acetate has many characteristics of an ideal phosphate binder. It is, for instance, a more readily soluble salt compared with calcium carbonate. This advantage might, however, disappear if calcium carbonate is taken on an empty stomach, a few minutes before meals. We examined the efficacy of three different phosphate binding agents in a randomized prospective study of 53 patients on regular hemodialysis. Bicarbonate dialyses were performed with a dialysate calcium concentration of 1.75 mmol/l. After a three-week wash-out period, patients received either aluminum hydroxide (control group), calcium acetate, or calcium carbonate as their phosphate binder. Patients were instructed to take the calcium salts a few minutes before meals on an empty stomach, and aluminum hydroxide during meals. Serum calcium, phosphate, intact parathormone, and alkaline phosphatase levels were determined every month. Patient compliance was estimated every month by asking the patients which phosphate binder and what daily dose they had used. Aluminum hydroxide tended to be the most effective phosphate binder. The mean +/- SEM required daily dose of calcium acetate at 12 months was 5.04 +/- 0.60 g, corresponding to 10.1 +/- 1.20 tablets of 500 mg. Co-medication with aluminum hydroxide, however, was needed (1.29 +/- 0.54 g per day, corresponding to 2.6 +/- 1.08 tablets of 500 mg). The required daily calcium carbonate dose appeared to be 2.71 +/- 0.48 g, corresponding to 5.4 +/- 0.95 capsules of 500 mg, with an adjuvant daily aluminum hydroxide dose of 0.69 +/- 0.27 g, corresponding to 1.4 +/- 0.55 tablets of 500 mg (p = 0.0055). Thus, the mean daily doses of elemental calcium were comparable between the calcium acetate and calcium carbonate-treated patients (1.28 +/- 0.15 g versus 1.09 +/- 0.19 g; n.s.). The incidence of hypercalcemic episodes (albumin-corrected serum calcium levels above 2.80 mmol/l) in the calcium acetate-treated group was 18% versus 31% in the calcium carbonate-treated group (p < 0.005). None of the aluminum hydroxide-treated patients experienced hypercalcemic episodes. Mean serum concentrations of alkaline phosphatase, intact parathormone, and aluminum did not differ between the groups. In chronic intermittent hemodialysis patients, per gram administered elemental calcium phosphate binding with either calcium acetate or calcium carbonate is equivalent, provided that calcium carbonate is taken on an empty stomach a few minutes before meals. The number of capsules calcium carbonate, but also the total amount in grams, necessary to keep serum phosphate and intact parathormone levels into an acceptable range then is significantly less. This might improve patient compliance.

Proteomic analysis of a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate: a case report.

PubMed

Kaneko, Kiyoko; Matsuta, Yosuke; Moriyama, Manabu; Yasuda, Makoto; Chishima, Noriharu; Yamaoka, Noriko; Fukuuchi, Tomoko; Miyazawa, Katsuhito; Suzuki, Koji

2014-03-01

The objective of the present study was to investigate the matrix protein of a rare urinary stone that contained calcium carbonate. A urinary stone was extracted from a 34-year-old male patient with metabolic alkalosis. After X-ray diffractometry and infrared analysis of the stone, proteomic analysis was carried out. The resulting mass spectra were evaluated with protein search software, and matrix proteins were identified. X-ray diffraction and infrared analysis confirmed that the stone contained calcium carbonate and calcium oxalate dihydrate. Of the identified 53 proteins, 24 have not been previously reported from calcium oxalate- or calcium phosphate-containing stones. The protease inhibitors and several proteins related to cell adhesion or the cytoskeleton were identified for the first time. We analyzed in detail a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate. Considering the formation of a calcium carbonate stone, the new identified proteins should play an important role on the urolithiasis process in alkaline condition. © 2013 The Japanese Urological Association.

Distribution of biogenic silica and quartz in recent deep-sea sediments

NASA Astrophysics Data System (ADS)

Leinen, Margaret; Cwienk, Douglas; Heath, G. Ross; Biscaye, Pierre E.; Kolla, V.; Thiede, Jørn; Dauphin, J. Paul

1986-03-01

All available quartz and biogenic silica concentrations from deep-sea surface sediments were intercalibrated, plotted, and contoured on a calcium-carbonate-free basis. The maps show highest concentrations of biogenic silica (opal) along the west African coast, along equatorial divergences in all oceans, and at the Polar Front in the southern Indian Ocean. These are all areas where upwelling is strong and there is high biological productivity. Quartz in pelagic sediments deposited far from land is generally eolian in origin. Its distribution reflects dominant wind systems in the Pacific, but in much of the Atlantic and Indian oceans the distribution pattern is strongly modified by turbidite deposition and bottom current processes.

Conventional Radiology in Crystal Arthritis: Gout, Calcium Pyrophosphate Deposition, and Basic Calcium Phosphate Crystals.

PubMed

Jacques, Thibaut; Michelin, Paul; Badr, Sammy; Nasuto, Michelangelo; Lefebvre, Guillaume; Larkman, Neal; Cotten, Anne

2017-09-01

This article reviews the main radiographic features of crystal deposition diseases. Gout is linked to monosodium urate crystals. Classic radiographic features include subcutaneous tophi, large and well-circumscribed paraarticular bone erosions, and exuberant bone hyperostosis. Calcium pyrophosphate deposition (CPPD) can involve numerous structures, such as hyaline cartilages, fibrocartilages, or tendons. CPPD arthropathy involves joints usually spared by osteoarthritis. Basic calcium phosphate deposits are periarticular or intraarticular. Periarticular calcifications are amorphous, dense, and round or oval with well-limited borders, and most are asymptomatic. When resorbing, they become cloudy and less dense with an ill-defined shape and can migrate into adjacent structures. Copyright © 2017 Elsevier Inc. All rights reserved.

Measurement of the efficacy of calcium silicate for the protection and repair of dental enamel.

PubMed

Parker, Alexander S; Patel, Anisha N; Al Botros, Rehab; Snowden, Michael E; McKelvey, Kim; Unwin, Patrick R; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo

2014-06-01

To investigate the formation of hydroxyapatite (HAP) from calcium silicate and the deposition of calcium silicate onto sound and acid eroded enamel surfaces in order to investigate its repair and protective properties. Calcium silicate was mixed with phosphate buffer for seven days and the resulting solids analysed for crystalline phases by Raman spectroscopy. Deposition studies were conducted on bovine enamel surfaces. Acid etched regions were produced on the enamel surfaces using scanning electrochemical cell microscopy (SECCM) with acid filled pipettes and varying contact times. Following treatment with calcium silicate, the deposition was visualised with FE-SEM and etch pit volumes were measured by AFM. A second set of bovine enamel specimens were pre-treated with calcium silicate and fluoride, before acid exposure with the SECCM. The volumes of the resultant acid etched pits were measured using AFM and the intrinsic rate constant for calcium loss was calculated. Raman spectroscopy confirmed that HAP was formed from calcium silicate. Deposition studies demonstrated greater delivery of calcium silicate to acid eroded than sound enamel and that the volume of acid etched enamel pits was significantly reduced following one treatment (p<0.05). In the protection study, the intrinsic rate constant for calcium loss from enamel was 0.092 ± 0.008 cm/s. This was significantly reduced, 0.056 ± 0.005 cm/s, for the calcium silicate treatments (p<0.0001). Calcium silicate can transform into HAP and can be deposited on acid eroded and sound enamel surfaces. Calcium silicate can provide significant protection of sound enamel from acid challenges. Calcium silicate is a material that has potential for a new approach to the repair of demineralised enamel and the protection of enamel from acid attacks, leading to significant dental hard tissue benefits. © 2014 Elsevier Ltd. All rights reserved.

Calcium carbonate does not affect nilotinib pharmacokinetics in healthy volunteers.

PubMed

Tawbi, Hussein A; Tran, An L; Christner, Susan M; Lin, Yan; Johnson, Matthew; Mowrey, Emily; Appleman, Leonard R; Stoller, Ronald; Miller, Brian M; Egorin, Merrill J; Beumer, Jan H

2013-11-01

Gastric upset is a common side effect of nilotinib therapy, and calcium carbonate is frequently used concomitantly, either as antacid or as calcium supplementation. With the increasing number of oral agents in cancer therapy, oral drug-drug interactions are becoming more relevant. Nilotinib has already been shown to be absorbed to a much lesser extent when co-administered with proton pump inhibitors. Because exposure to sub-therapeutic concentrations of anticancer drugs such as nilotinib may result in selection of resistant clones and ultimately relapse, we studied the effect of a calcium carbonate supplement (Tums Ultra 1000®) on nilotinib pharmacokinetics. Calcium carbonate may be co-administered with nilotinib without significantly affecting the pharmacokinetics of nilotinib and potentially impacting efficacy. Nilotinib is a second-generation oral tyrosine kinase inhibitor with superior efficacy compared with imatinib mesylate in the treatment for chronic phase chronic myelogenous leukemia. Calcium carbonate is commonly used as a source of calcium supplementation or as antacid to ameliorate the gastrointestinal side effects associated with nilotinib, which could have unknown effects on nilotinib absorption. The purpose of this study was to provide information on the effect of calcium carbonate on the PK of nilotinib in healthy volunteers. Healthy subjects were enrolled in a two-period, open-label, single-institution, randomized, cross-over, fixed-schedule study. In one period, each subject received 400 mg of nilotinib p.o. In the other period, 4,000 mg of calcium carbonate (4 X Tums Ultra 1000®) was administered p.o. 15 min prior to the nilotinib dose. Plasma samples were collected at specified timepoints, concentrations of nilotinib were quantitated by LC-MS, and data were analyzed non-compartmentally. Eleven subjects were evaluable. Calcium supplementation did not significantly affect nilotinib pharmacokinetic parameters including area under the plasma concentration versus time curve (18.4 μg/mL h alone vs. 16.9 μg/mL h with calcium carbonate, p = 0.83; 80 % power); maximum plasma concentration (C(max)) (0.670 μg/mL alone vs. 6.18 μg/mL with calcium carbonate, p = 0.97); or half-life (18.9 h alone vs. 17.2 h with calcium carbonate, p = 0.18). Our results indicate that the use of calcium carbonate does not significantly affect nilotinib pharmacokinetics.

Spectroscopic characterisation of moonmilk deposits in Pozalagua tourist Cave (Karrantza, Basque Country, North of Spain)

NASA Astrophysics Data System (ADS)

Martínez-Arkarazo, I.; Angulo, M.; Zuloaga, O.; Usobiaga, A.; Madariaga, J. M.

2007-12-01

Composition of moonmilk deposits located in different zones of the tourist Dolomite Cave of Pozalagua (Karrantza, Basque Country, North of Spain) was established by Raman spectroscopy. The deposits were located in column bases and detached rocks near a gour full of water or a dripping zone. Hydromagnesite (Mg 5(CO 3) 4(OH) 2·4H 2O) with a strong Raman band at 1116 cm -1 and weaker ones at 1522vw, 1487vw, 1452vw, 756w, 727w, 466w, 434w, 371w, 327m, 291w, 258w, 247vw and 230 m cm -1 was found as the main component of the moonmilk. Aragonite is the unique calcium carbonate compound that sometimes composes the moonmilk but always together with the hydromagnesite. Among non-carbonate minerals, some nitrates (nitrocalcite, niter, nitromagnesite, nitratine and gwihabaite) and sulphates (arkanite) were also identified as minor compounds. Most of the deposits were matt white and pasty, but occasionally some samples appear greyish on the surface. In these samples, carbon particles were also found, apart from the above, and Raman shift changes were observed in the hydromagnesite spectra. Apart from the elements involved in the mentioned minerals, Si, Fe, Mn, Zn and Ti were identified by X-ray microfluorescence as trace elements and the results were correlated with mineral compositions found by Raman measurements. Furthermore, quantification of the soluble salts of moonmilk deposits was carried out by ionic chromatography and the results were chemometrically treated to find correlations among soluble ions and the composition of the mineral phases spectroscopically characterised.

Spectroscopic characterisation of moonmilk deposits in Pozalagua tourist cave (Karrantza, Basque Country, North of Spain).

PubMed

Martínez-Arkarazo, I; Angulo, M; Zuloaga, O; Usobiaga, A; Madariaga, J M

2007-12-15

Composition of moonmilk deposits located in different zones of the tourist Dolomite Cave of Pozalagua (Karrantza, Basque Country, North of Spain) was established by Raman spectroscopy. The deposits were located in column bases and detached rocks near a gour full of water or a dripping zone. Hydromagnesite (Mg(5)(CO(3))(4)(OH)(2).4H(2)O) with a strong Raman band at 1116 cm(-1) and weaker ones at 1522vw, 1487vw, 1452vw, 756w, 727w, 466w, 434w, 371w, 327m, 291w, 258w, 247vw and 230 m cm(-1) was found as the main component of the moonmilk. Aragonite is the unique calcium carbonate compound that sometimes composes the moonmilk but always together with the hydromagnesite. Among non-carbonate minerals, some nitrates (nitrocalcite, niter, nitromagnesite, nitratine and gwihabaite) and sulphates (arkanite) were also identified as minor compounds. Most of the deposits were matt white and pasty, but occasionally some samples appear greyish on the surface. In these samples, carbon particles were also found, apart from the above, and Raman shift changes were observed in the hydromagnesite spectra. Apart from the elements involved in the mentioned minerals, Si, Fe, Mn, Zn and Ti were identified by X-ray microfluorescence as trace elements and the results were correlated with mineral compositions found by Raman measurements. Furthermore, quantification of the soluble salts of moonmilk deposits was carried out by ionic chromatography and the results were chemometrically treated to find correlations among soluble ions and the composition of the mineral phases spectroscopically characterised.

Synthesis of Calcite Nano Particles from Natural Limestone assisted with Ultrasonic Technique

NASA Astrophysics Data System (ADS)

Handayani, M.; Sulistiyono, E.; Firdiyono, F.; Fajariani, E. N.

2018-03-01

This article represents a precipitation method assisted with ultrasonic process to synthesize precipitated calcium carbonate nano particles from natural limestone. The synthesis of nanoparticles material of precipitated calcium carbonate from commercial calcium carbonate was done for comparison. The process was performed using ultrasonic waves at optimum condition, that is, at temperature of 80oC for 10 minutes with various amplitudes. Synthesized precipitated calcium carbonate nanoparticles were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Particle Size Analyzer (PSA). The result of PSA measurements showed that precipitated calcium carbonate nano particles was obtained with the average size of 109 nm.

Conversion of alkali metal sulfate to the carbonate

DOEpatents

Sheth, Atul C.

1982-01-01

A process for converting potassium sulfate to potassium carbonate in which a mixture of potassium sulfate and calcium oxide are reacted at a temperature in the range of between about 700.degree. C. and about 800.degree. C. with a gaseous mixture having a minor amount of hydrogen and/or carbon monoxide in a diluent with the calcium oxide being present in an amount not greater than about 20 percent by weight of the potassium sulfate to produce an aqueous mixture of potassium sulfide, potassium bisulfide, potassium hydroxide and calcium sulfide and a gaseous mixture of steam and hydrogen sulfide. The potassium and calcium salts are quenched to produce an aqueous slurry of soluble potassium salts and insoluble calcium salts and a gaseous mixture of steam and hydrogen sulfide. The insoluble calcium salts are then separated from the aqueous solution of soluble potassium salts. The calcium salts are dried to produce calcium sulfide, calcium bisulfide and steam, and then, the calcium sulfide and calcium bisulfide are converted to the oxide and recycled. The soluble potassium salts are carbonated to produce potassium carbonate which is concentrated and the precipitated crystals separated. The sulfur-containing compounds are further treated.

STUDIES UPON CALCAREOUS DEGENERATION

PubMed Central

Klotz, Oskar

1905-01-01

It will be seen from the above that we have studied the conditions associated with the deposit of calcareous salts: (I) in connection with normal and pathological ossification, and (2) in pathological calcification as exhibited in (a) atheroma of the vessels; (b) calcification of caseating tubercular lesions; (c) calcification of inflammatory new growth, and (d) degenerating tumors; and we have induced experimentally deposits of calcareous salts in the lower animals: (a) within celloidin capsules containing fats and soaps; (b) in the kidney, and (c) in connection with fat necrosis. I. We have found that bone formation and pathological calcareous infiltration are wholly distinct processes. In the former there is no evidence of associated fatty change, and the cells associated with the process of deposition of calcium are functionally active. In the latter there is an antecedent fatty change in the affected areas, and the cells involved present constant evidences of degeneration. The view that would seem to account best for the changes observed in the latter case is that with lowered vitality the cells are unable to utilize the products brought to them by the blood, or which they continue to absorb, so that the normal series of decompositions associated with their metabolism fails to take place and hence they interact among themselves in the cytoplasm with the result that insoluble compounds replace soluble ones. II. Besides the fact that calcification is always preceded by fatty change within the cells, another fact should be emphasized. namely: that combination of the fats present with calcium salts to form calcium soaps tends to occur. The stages immediately preceding these are difficult to follow with anything approaching certainty, perhaps because the earlier stages vary under different conditions. In fat necrosis, for instance, the cells affected are normally storehouses for neutral fats, and as long as they remain healthy neutral fats alone are present in them. When they are subjected to the action of the pancreatic juice with its fat-splitting ferment the cells are killed and coincidently the neutral fats are decomposed, fatty acids being deposited. The fatty acids now slowly combine with the calcium salts. In degenerating lipomata the process would seem to be similar. But in other cases the cells are not obviously fat-containing in the normal state; nevertheless prior to calcification they undergo so-called fatty degeneration, which is really a form of cell degeneration accompanied by fat infiltration. As regards the source of the cell fats in general we may safely accept: 1. That fats are transported in the blood as diffusible soaps. 2. That taken up by the cells these soaps may either— (a) Be reconverted into neutral fats and become stored in the cytoplasm as such, or (b) undergo assimilation proper, becoming part and parcel of the cell substance, in which case they are not recognizable by the ordinary microchemical tests. 3. If these two possibilities be accepted it follows that the appearance of fats and soaps in the degenerating cell may be due to either— (a) Absorption or infiltration of soaps from the surrounding medium, the degenerating cell retaining the power of splitting off the fat but being unable to utilize this in metabolism. (b) Cytoplasmic disintegration with dissociation of the soap-albumen combination or, more broadly, liberation of the fats from their combination with the cytoplasm. The appearances seen in the cells of atheromatous areas indicate that the first of these does occur. III. In areas undergoing calcareous infiltration we have demonstrated. the presence of soaps, and this often in such quantities that they can be isolated and estimated by gross chemical methods. By microchemical methods also we have been able to show that after removing all the neutral fats and fatty acids by petroleum ether there remains behind a substance giving with Sudan III the reaction we associate with the presence of soap. And experimentally we have produced these soaps within the organism, more particularly by placing capsules containing fats and fatty acids within the tissues and after several days finding that the capsules contain calcium soaps and possess a calcium content far in excess of that of the normal blood and lymph. IV. While these are the facts, certain of the details of this reaction demand elucidation. The existence of sodium and it may be potassium soaps in the degenerated cells is comprehensible if we accept that these are present in the circulating lymph and simply undergoing absorption. But even then, as these are diffusible substances how is it to be explained that they become stored up in these particular areas? We have found that, as a matter of fact, in regions which give the reaction for soaps, but which give no reaction for calcium (which therefore presumably contain at most amounts of the insoluble calcium soap too small to need consideration, the ordinary solvents for potassium and sodium soaps do not forthwith remove the stainable material; they are relatively insoluble. The reason for this insolubility is suggested by the observations made in the test tube, that soap solutions mixed with solutions of white of egg or blood serum form a precipitate of combined soap and albumen, which likewise is insoluble in water and alcohol. The indications are therefore that in cells undergoing degeneration, with degeneration of the cytoplasm, certain albuminous molecules unite with the soaps present to form relatively insoluble soap-albuminate. V. With regard to calcium soaps, these are also present and in certain stages appear to be the dominating form in the affected tissues. Two questions suggest themselves, viz.: what is the source of calcium, and what is the process by which they become formed? As to the source, the amount present in well-marked calcification is far in excess of the normal calcium contents of the affected tissue. If in the kidneys of experimental calcification three hundred times as much calcium may be present as in the normal kidney (von Kossa), the calcium must be conveyed to the part by the blood and lymph, and that this is so is demonstrated, as we have pointed out, by the distribution of the infiltration in solid organs, that like ovarian fibroids have undergone necrosis, in which the earliest deposits are superficial. As to the process, there are three possibilities: 1. That sodium and potassium soaps and soap albuminates are first formed and that interaction occurs between them and the diffused calcium salts from the lymph, the less soluble-calcium replacing the sodium and potassium. 2. That under certain conditions the calcium salts act directly on the neutral fats present in the degenerating cells. 3. That the neutral fats are first broken down into fatty acids and that these react with the calcium salts to form the soaps. We are assured that the first process occurs and that because in the boundary zone of areas of calcification we can detect soapy particles devoid of calcium, identical in position and arrangement with the particles more deeply placed which give the calcium reactions. But this is not the only reaction. In case of fat necrosis we see clearly that the third process is in evidence. And we are far from being convinced that the second does not also obtain. We have been impressed by the large accumulation of neutral fats in the cells in cases of early atheroma and the absence at any stage of the process of recognizable fatty acid. While soaps, it is true, are compounds of fatty acids with alkalies, it is recognized in ordinary domestic life that they can be formed by the direct action of strong lye upon ordinary fats, and this even in the cold. It is quite possible therefore that there occurs a similar direct process in the organism. The point is worth noting, however, that this does not occur in healthy cells the seat of fatty infiltration. We therefore leave this an open question, only laying down that, as indicated by the hyalin albuminous matrix left when calcium salts are dissolved out of an area of calcification, there must exist a calcium soap- or fat-albuminate similar to the potassium and sodium soap-albuminates already mentioned—such an albuminate as we can form with calcium soaps in the test tube. VI. In old areas of calcification soaps are largely if not entirely wanting, although these are to be detected at the periphery, when the process is still advancing. The reactions given by these older areas are almost entirely those of calcium phosphate, though some calcium carbonate is at times to be made out. This seems surely to indicate that the final stage in calcification is an interaction between the calcium soap-albuminates and substances containing phosphoric and carbonic acids. Such substances, it is needless to say, are present in considerable amounts in the lymph and blood. We must conclude that the acid sodium phosphates of the lymph act on the calcium soap, the highly insoluble calcium phosphates being formed (plus the albuminous moiety of the original compound) and diffusible sodium soap being liberated, while similarly alkaline carbonates form calcium carbonate and liberate sodium and potassium soaps. Calcium phosphate and calcium carbonate thus become the insoluble earthy salts of old crystalline areas of calcification. VII. As already stated very little soap is to be found in these old areas. It is possibly worth suggestion that the soaps liberated in this last reaction, as they diffuse out, again react with diffusible calcium salts and form calcium soaps which once more react with the alkaline salts to produce the phosphates and carbonates; that, in short, they have a katalytic action. Certain it is that old calcareous areas are extraordinarily dense, and have a coarse crystalline structure, wholly at variance with the finely granular appearance of the more recent areas, and these large crystalline masses, it would seem, can only be formed by successive deposition of new material and eventual fusion, as the interspaces become filled in between the original masses. PMID:19867016

SECONDARY HYPERPARATHYROIDISM AFTER BARIATRIC SURGERY: TREATMENT IS WITH CALCIUM CARBONATE OR CALCIUM CITRATE?

PubMed Central

BARETTA, Giorgio Alfredo Pedroso; CAMBI, Maria Paula Carlini; RODRIGUES, Arieli Luz; MENDES, Silvana Aparecida

2015-01-01

Background : Bariatric surgery, especially Roux-en-Y gastric bypass, can cause serious nutritional complications arising from poor absorption of essential nutrients. Secondary hyperparathyroidism is one such complications that leads to increased parathyroid hormone levels due to a decrease in calcium and vitamin D, which may compromise bone health. Aim : To compare calcium carbonate and calcium citrate in the treatment of secondary hyperparathyroidism. Method : Patients were selected on the basis of their abnormal biochemical test and treatment was randomly done with citrate or calcium carbonate. Results : After 60 days of supplementation, biochemical tests were repeated, showing improvement in both groups. Conclusion : Supplementation with calcium (citrate or carbonate) and vitamin D is recommended after surgery for prevention of secondary hyperparathyroidism. PMID:26537273

Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

ERIC Educational Resources Information Center

Henrickson, Charles H.; Robinson, Paul R.

1979-01-01

The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

Stable prenucleation mineral clusters are liquid-like ionic polymers

PubMed Central

Demichelis, Raffaella; Raiteri, Paolo; Gale, Julian D.; Quigley, David; Gebauer, Denis

2011-01-01

Calcium carbonate is an abundant substance that can be created in several mineral forms by the reaction of dissolved carbon dioxide in water with calcium ions. Through biomineralization, organisms can harness and control this process to form various functional materials that can act as anything from shells through to lenses. The early stages of calcium carbonate formation have recently attracted attention as stable prenucleation clusters have been observed, contrary to classical models. Here we show, using computer simulations combined with the analysis of experimental data, that these mineral clusters are made of an ionic polymer, composed of alternating calcium and carbonate ions, with a dynamic topology consisting of chains, branches and rings. The existence of a disordered, flexible and strongly hydrated precursor provides a basis for explaining the formation of other liquid-like amorphous states of calcium carbonate, in addition to the non-classical behaviour during growth of amorphous calcium carbonate. PMID:22186886

Idiopathic hypercalciuria and formation of calcium renal stones

PubMed Central

Coe, Fredric L.; Worcester, Elaine M.; Evan, Andrew P.

2018-01-01

The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate and form on a base of interstitial apatite deposits, known as Randall’s plaque. By contrast some stones are composed largely of calcium phosphate, as either hydroxyapatite or brushite (calcium monohydrogen phosphate), and are usually accompanied by deposits of calcium phosphate in the Bellini ducts. These deposits result in local tissue damage and might serve as a site of mineral overgrowth. Stone formation is driven by supersaturation of urine with calcium oxalate and brushite. The level of supersaturation is related to fluid intake as well as to the levels of urinary citrate and calcium. Risk of stone formation is increased when urine citrate excretion is <400 mg per day, and treatment with potassium citrate has been used to prevent stones. Urine calcium levels >200 mg per day also increase stone risk and often result in negative calcium balance. Reduced renal calcium reabsorption has a role in idiopathic hypercalciuria. Low sodium diets and thiazide-type diuretics lower urine calcium levels and potentially reduce the risk of stone recurrence and bone diseas PMID:27452364

Preferential soft-tissue preservation in the Hot Creek carbonate spring deposit, British Columbia, Canada

NASA Astrophysics Data System (ADS)

Rainey, Dustin K.; Jones, Brian

2010-05-01

The relict Holocene Hot Creek carbonate spring deposit in southeast British Columbia is characterized by excellent preservation of soft-tissue organisms (e.g. cyanobacteria), but poor preservation of organisms with hard-tissue (e.g. wood, diatoms). The deposit is formed mainly of calcified cyanobacteria, with fewer mineralized macrophytes (plants), bryophytes (mosses), wood, and diatoms. Cyanobacteria grew as solitary filaments ( Lyngbya) and as radiating hemispherical colonies ( Rivularia). Both were preserved by encrustation and encapsulation while alive, and as casts after filament death and decay. Sheath impregnation was rare to absent. Filament encrustation, whereby calcite crystals nucleated on, and grew away from the sheath exterior, produced moulds that replicated external filament morphology, but hastened filament decay. Filament encapsulation, whereby calcite nucleated in the vicinity of, and grew towards the encapsulated filament, promoted sheath preservation even after trichome decay. Subsequent calcite precipitation inside the hollow sheath generated sheath casts. The inability of mineralizing spring water to penetrate durable cell walls meant that bryophytes, macrophytes, and most wood was preserved by encrustation. Some wood resisted complete decay for several thousand years, and its lignified cell walls allowed rare permineralizations. Diatoms were not preserved in the relict deposit because the frustules were dissolved by the basic spring water. Amorphous calcium carbonate produced by photosynthetic CO 2 removal may have acted as nucleation sites for physicochemically precipitated calcite. Thus, metabolic activities of floral organisms probably initiated biotic mineralization, but continuous inorganic calcite precipitation on and in flora ensured that soft tissues were preserved.

Atypical localizations of calcific deposits in the shoulder

PubMed Central

Vinanti, G.B.; Pavan, D.; Rossato, A.; Biz, Carlo

2015-01-01

Introduction Calcific tendinopathies of the shoulder are due to inflammation around deposits of calcium within periarticular tendineal structures. Presentation of cases We present three cases of atypical localization of calcium deposits in the shoulder. All of the cases have been treated with arthroscopic excision, followed by post-operative rehabilitation, regaining excellent results. Patients were evaluated 6 months after surgery using the Visual Analogue Scale (VAS), the Simple Shoulder Test (SST) and the UCLA modified shoulder rating. Discussion Calcific tendinopathy is a self-limiting condition or is successfully treated with conservative therapy especially during the early phases of the pathology. If conservative measures fail, removal of calcium deposits is recommended. Arthroscopic management showed good results in our three cases. Conclusion We suggest that arthroscopic treatment of calcific tendonitis guarantees good results even when calcium deposits are in atypical locations. PMID:25884610

Impregnating Coal With Calcium Carbonate

NASA Technical Reports Server (NTRS)

Sharma, Pramod K.; Voecks, Gerald E.; Gavalas, George R.

1991-01-01

Relatively inexpensive process proposed for impregnating coal with calcium carbonate to increase rates of gasification and combustion of coal and to reduce emission of sulfur by trapping sulfur in calcium sulfide. Process involves aqueous-phase reactions between carbon dioxide (contained within pore network of coal) and calcium acetate. Coal impregnated with CO2 by exposing it to CO2 at high pressure.

Gallbladder mucin production and calcium carbonate gallstones in children.

PubMed

Sayers, Craig; Wyatt, Judy; Soloway, Roger D; Taylor, Donald R; Stringer, Mark D

2007-03-01

In contrast to adults, calcium carbonate gallstones are relatively common in children. Their pathogenesis is poorly understood. Cystic duct obstruction promotes calcium carbonate formation in bile and increases gallbladder mucin production. We tested the hypothesis that mucin producing epithelial cells would be increased in gallbladders of children with calcium carbonate gallstones. Archival gallbladder specimens from 20 consecutive children who had undergone elective cholecystectomy for cholelithiasis were examined. In each case, gallstone composition was determined by Fourier transform infrared microspectroscopy. Gallbladder specimens from six children who had undergone cholecystectomy for conditions other than cholelithiasis during the same period were used as controls. Multiple sections were examined in a blinded fashion and scored semiquantitatively for mucin production using two stains (alcian blue and periodic acid-Schiff). Increased mucin staining was observed in 50% or more epithelial cells in five gallbladder specimens from seven children with calcium carbonate stones, compared to 5 of 13 with other stone types (P = 0.17) and none of the control gallbladders (P = 0.02). Gallbladders containing calcium carbonate stones were significantly more likely than those containing other stone types or controls to contain epithelial cells with the greatest mucin content (P = 0.03). Gallbladders containing calcium carbonate stones were also more likely to show the ulcer-associated cell lineage. These results demonstrate an increase in mucin producing epithelial cells in gallbladders from children containing calcium carbonate stones. This supports the hypothesis that cystic duct obstruction leading to increased gallbladder mucin production may play a role in the development of calcium carbonate gallstones in children.

METHOD OF PRODUCING URANIUM METAL BY ELECTROLYSIS

DOEpatents

Piper, R.D.

1962-09-01

A process is given for making uranium metal from oxidic material by electrolytic deposition on the cathode. The oxidic material admixed with two moles of carbon per one mole of uranium dioxide forms the anode, and the electrolyte is a mixture of from 40 to 75% of calcium fluoride or barium fluoride, 15 to 45% of uranium tetrafluoride, and from 10 to 20% of lithium fluoride or magnesium fluoride; the temperature of the electrolyte is between 1150 and 1175 deg C. (AEC)

Radioisotope tracer studies of inorganic carbon and Ca in microbially derived CaCO3

USGS Publications Warehouse

Yates, Kimberly K.; Robbins, Lisa L.

1999-01-01

Microbial calcification significantly impacts the cycling and deposition of inorganic carbon. This research employs 45Ca and 14C techniques as radioisotopic tracers to examine the role of cellular cycling of Ca2+ and inorganic carbon in CaCO3 precipitation by the unicellular green alga Nannochloris atomus. Implications of the effects of these physiological aspects on CaCO3 precipitation and the effects of microbial calcification on CaCO3 δ13C ratios are discussed. Results from pulse/chase experiments indicate that intracellular Ca2+ is incorporated into extracellular CaCO3. Intracellular inorganic carbon leaks from cells within 10 to 12 s after injection of unlabelled NaHCO3, providing a source of inorganic carbon for extracellular CaCO3. Cellular expulsion of calcium plays a key role in increasing the CaCO3 saturation state at the site of calcification. The δ13C ratios of microbial carbonates may vary depending on the amount of photorespiratory CO2 incorporated.

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate. (e) When...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate. (e) When...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate. (e) When...

9 CFR 381.129 - False or misleading labeling or containers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... prescribed in § 381.132. (d) When sodium alginate, calcium carbonate, lactic acid, and calcium lactate are... indicate the use of sodium alginate, calcium carbonate, lactic acid, and calcium lactate.(e) When...

Inter-relationships between corrosion and mineral-scale deposition in aqueous systems.

PubMed

Hodgkiess, T

2004-01-01

The processes of corrosion and scale deposition in natural and process waters are often linked and this paper considers a number of instances of interactions between the two phenomena. In some circumstances a scale layer (e.g. calcium carbonate) can be advantageously utilised as a corrosion-protection coating on components and this feature has been exploited for many decades in the conditioning of water to induce spontaneous precipitation of a scale layer upon the surfaces of engineering equipment. The electrochemical mechanisms associated with some corrosion and corrosion-control processes can promote alkaline-scale deposition directly upon component surfaces. This is a feature that can be exploited in the operation of cathodic protection (CP) of structures and components submerged in certain types of water (e.g. seawater). Similar phenomena can occur during bi-metallic corrosion and a case study, involving carbon steel/stainless steel couples in seawater, is presented. Additional complexities pertain during cyclic loading of submerged reinforced concrete members in which scale deposition may reduce the severity of fatigue stresses but can be associated with severe corrosion damage to embedded reinforcing steel. Also considered are scale-control/corrosion interactions in thermal desalination plant and an indirect consequence of the scale-control strategy on vapourside corrosion is discussed.

Conversion of alkali metal sulfate to the carbonate

DOEpatents

Sheth, A.C.

1979-10-01

A process is described for converting potassium sulfate to potassium carbonate in which a mixture of potassium sulfate and calcium oxide are reacted at a temperature in the range of between about 700/sup 0/C and about 800/sup 0/C with a gaseous mixture having a minor amount of hydrogen and/or carbon monoxide in a diluent with the calcium oxide being present in an amount not greater than about 20 percent by weight of the potassium sulfate to produce an aqueous mixture of potassium sulfide, potassium bisulfide, potassium hydroxide and calcium sulfide and a gaseous mixture of steam and hydrogen sulfide. The potassium and calcium salts are quenched to produce an aqueous slurry of soluble potassium salts and insoluble calcium salts and a gaseous mixture of steam and hydrogen sulfide. The insoluble calcium salts are then separated from the aqueous solution of soluble potassium salts. The calcium salts are dried to produce calcium sulfide, calcium bisulfide and steam, and then, the calcium sulfide and calcium bisulfide are converted to the oxide and recycled. The soluble potassium salts are carbonated to produce potassium carbonate which is concentrated and the precipitated crystals separated. the sulfur-containing compounds are further treated. This process was developed for desulfurization and reprocessing of spent seed from open-cycle coal-fired MHD generators for reuse.

Influence of pulse ratio on codeposition of copper species with calcium phosphate coatings on titanium by means of electrochemically assisted deposition.

PubMed

Wolf-Brandstetter, Cornelia; Oswald, Steffen; Bierbaum, Susanne; Wiesmann, Hans-Peter; Scharnweber, Dieter

2014-01-01

Aim of this study was to combine the well-known biocompatibility and ostoeconductivity of thin calcium phosphate coatings on titanium with proangiogenic signals from codeposited copper species. Copper species could be integrated in mineral layers based on hydroxyapatite by means of electrochemically assisted deposition from electrolytes containing calcium, phosphate, and copper ions. Different combinations of duration and intensity of galvanostatic pulses result in different amounts of deposited calcium phosphate and of copper species even for the same applied total charge. Absolute amounts of copper varied between 2.1 and 6.9 μg/cm², and the copper was distributed homogeneously as shown by EDX mapping. The presence of copper did not change the crystalline phase of deposited calcium phosphate (hydroxyapatite) but provoked a significant decrease in deposited amounts by factor 3 to 4. The copper was deposited mainly as Cu(I) species with a minor fraction of basic copper phosphates. Reduction of copper occurred not only at the surface of titanium but also within the hydroxyapatite coating due to the reaction with hydrogen produced by the electrolysis of water during the cathodic polarization of the substrate. Copyright © 2013 Wiley Periodicals, Inc.

Sevelamer is cost effective versus calcium carbonate for the first-line treatment of hyperphosphatemia in new patients to hemodialysis: a patient-level economic evaluation of the INDEPENDENT-HD study.

PubMed

Ruggeri, Matteo; Bellasi, Antonio; Cipriani, Filippo; Molony, Donald; Bell, Cynthia; Russo, Domenico; Di Iorio, Biagio

2015-10-01

The recent multicenter, randomized, open-label INDEPENDENT study demonstrated that sevelamer improves survival in new to hemodialysis (HD) patients compared with calcium carbonate. The objective of this study was to determine the cost-effectiveness of sevelamer versus calcium carbonate for patients new to HD, using patient-level data from the INDEPENDENT study. Cost-effectiveness analysis. Adult patients new to HD in Italy. A patient-level cost-effectiveness analysis was conducted from the perspective of the Servizio Sanitario Nazionale, Italy's national health service. The analysis was conducted for a 3-year time horizon. The cost of dialysis was excluded from the base case analysis. Sevelamer was compared to calcium carbonate. Total life years (LYs), total costs, and the incremental cost per LY gained were calculated. Bootstrapping was used to estimate confidence intervals around LYs, costs, and cost-effectiveness and to calculate the cost-effectiveness acceptability curve. Sevelamer was associated with a gain of 0.26 in LYs compared to calcium carbonate, over the 3-year time horizon. Total drug costs were €3,282 higher for sevelamer versus calcium carbonate, while total hospitalization costs were €2,020 lower for sevelamer versus calcium carbonate. The total incremental cost of sevelamer versus calcium carbonate was €1,262, resulting in a cost per LY gained of €4,897. The bootstrap analysis demonstrated that sevelamer was cost effective compared with calcium carbonate in 99.4 % of 10,000 bootstrap replicates, assuming a willingness-to-pay threshold of €20,000 per LY gained. Data on hospitalizations was taken from a post hoc retrospective chart review of the patients included in the INDEPENDENT study. Patient quality of life or health utility was not included in the analysis. Sevelamer is a cost-effective alternative to calcium carbonate for the first-line treatment of hyperphosphatemia in new to HD patients in Italy.

The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

PubMed

Lucassen, Friedrich; Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A

2017-01-01

Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very heavy values generate a compositionally unique material. These compositions trace the presence of guano in natural ecosystems and its use as fertilizer in present and past agriculture.

The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile – Marine sources and diagenetic effects

PubMed Central

Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A.

2017-01-01

Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very heavy values generate a compositionally unique material. These compositions trace the presence of guano in natural ecosystems and its use as fertilizer in present and past agriculture. PMID:28594902

Mechanisms of the inhibition of enzymatic hydrolysis of waste pulp fibers by calcium carbonate and the influence of nonionic surfactant for mitigation.

PubMed

Min, Byeong Cheol; Ramarao, Bandaru V

2017-06-01

Recycled paper mills produce large quantities of fibrous rejects and fines which are usually sent to landfills as solid waste. These cellulosic materials can be enzymatically hydrolyzed into sugars for the production of biofuels and biomaterials. Paper mill wastes also contain large amounts of calcium carbonate which inhibits cellulase activity. The calcium carbonate (30%, w/w) decreased 40-60% of sugar yield of unbleached softwood kraft pulp. The prime mechanisms for this are by pH variation, competitive and non-productive binding, and aggregation effect. Addition of acetic acid (pH adjustment) increased the sugar production from 19 to 22 g/L of paper mill waste fibers. Strong affinity of enzyme-calcium carbonate decreased free enzyme in solution and hindered sugar production. Electrostatic and hydrogen bond interactions are mainly possible mechanism of enzyme-calcium carbonate adsorption. The application of the nonionic surfactant Tween 80 alleviated the non-productive binding of enzyme with the higher affinity on calcium carbonate. Dissociated calcium ion also inhibited the hydrolysis by aggregation of enzyme.

Block copolymers for biomimetic composites

NASA Astrophysics Data System (ADS)

Calvert, Paul D.; Oner, Mualla; Burdon, Jeremy; Rieke, Peter C.; Farmer, Kelly

1993-07-01

Mineralized biological tissues can be regarded as composites where a fine reinforcement is laid down in a very controlled fashion within a tough polymeric matrix. Such materials include bone, antler, tooth enamel, mollusc shell, and crustacean shell. We have been exploring ways of forming similar structures by synthetic routes involving precipitation of reinforcing particles directly into a polymeric matrix. Part of this biomimetic approach requires polymer matrices which can exert a high degree of control over the mineralization process. Polymer gels have been formed from cross-linked methacrylates with various types of functionality within the gel. By incorporating calcium binding groups we have been producing gels which lead to preferential mineralization of the gel when it is incubated in a supersaturated solution of calcium oxalate or calcium carbonate. Similarly we have been incorporating silane groups within the gel in order to promote the deposition of silica in a gel body when it is immersed in a metastable solution of partly hydrolysed silicon alkoxides.

Incremental cost-utility of sevelamer relative to calcium carbonate for treatment of hyperphosphatemia among pre-dialysis chronic kidney disease patients.

PubMed

Nguyen, Hai V; Bose, Saideep; Finkelstein, Eric

2016-04-28

Sevelamer is an alternative to calcium carbonate for the treatment of hyperphosphatemia among non-dialysis dependent patients with chronic kidney disease (CKD). Although some studies show that it may reduce mortality and delay the onset of dialysis when compared to calcium carbonate, it is also significantly more expensive. Prior studies looking at the incremental cost-effectiveness of sevelamer versus calcium carbonate in pre-dialysis patients are based on data from a single clinical trial. The goal of our study is to use a wider range of clinical data to achieve a more contemporary and robust cost-effectiveness analysis. We used a Markov model to estimate the lifetime costs and quality-adjusted life years (QALYs) gained for treatment with sevelamer versus calcium carbonate. The model simulated transitions among three health states (CKD not requiring dialysis, end-stage renal disease, and death). Data on transition probabilities and utilities were obtained from the published literature. Costs were calculated from a third party payer perspective and included medication, hospitalization, and dialysis. Sensitivity analyses were also run to encompass a wide range of assumptions about the dose, costs, and effectiveness of sevelamer. Over a lifetime, the average cost per patient treated with sevelamer is S$180,724. The estimated cost for patients treated with calcium carbonate is S$152,988. A patient treated with sevelamer gains, on average, 6.34 QALYs relative to no treatment, whereas a patient taking calcium carbonate gains 5.81 QALYs. Therefore, sevelamer produces an incremental cost-effectiveness ratio (ICER) of S$51,756 per QALY gained relative to calcium carbonate. Based on established benchmarks for cost-effectiveness, sevelamer is cost effective relative to calcium carbonate for the treatment of hyperphosphatemia among patients with chronic kidney disease initially not on dialysis.

Calcium and organic matter removal by carbonation process with waste incineration flue gas towards improvement of leachate biotreatment performance.

PubMed

Zhang, Cheng; Zhu, Xuedong; Wu, Liang; Li, Qingtao; Liu, Jianyong; Qian, Guangren

2017-09-01

Municipal solid wastes incineration (MSWI) flue gas was employed as the carbon source for in-situ calcium removal from MSWI leachate. Calcium removal efficiency was 95-97% with pH of 10.0-11.0 over 100min of flue gas aeration, with both bound Ca and free Ca being removed effectively. The fluorescence intensity of tryptophan, protein-like and humic acid-like compounds increased after carbonation process. The decrease of bound Ca with the increase of precipitate indicated that calcium was mainly converted to calcium carbonate precipitate. It suggested that the interaction between dissolved organic matter and Ca 2+ was weakened. Moreover, 10-16% of chemical oxygen demand removal and the decrease of ultraviolet absorption at 254nm indicated that some organics, especially aromatic compound decreased via adsorption onto the surface of calcium carbonate. The results indicate that introduce of waste incineration flue gas could be a feasible way for calcium removal from leachate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of sevelamer and calcium carbonate on endothelial function and inflammation in patients on peritoneal dialysis.

PubMed

Chennasamudram, Sudha P; Noor, Tanjila; Vasylyeva, Tetyana L

2013-06-01

Hyperphosphataemia is a known independent risk factor for cardiovascular mortality. The objective of the study was to compare the effects of two phosphate binders, sevelamer carbonate and calcium carbonate on endothelial function (EF) and inflammation in patients on peritoneal dialysis (PD) with Type 2 diabetes mellitus (T2DM). Fifteen subjects with hyperphosphataemia discontinued all phosphate binders to undergo a two-week washout and were assigned to sevelamer carbonate or calcium carbonate treatments for eight weeks. After a second two-week washout period, subjects crossed over to either of the alternate treatments for another eight weeks. At the beginning and end of each treatment, biomarkers of EF, pro-inflammatory cytokines, serum albumin, calcium, phosphate and lipids were measured. Sevelamer carbonate significantly improved lipid profile compared with calcium carbonate. Amongst the EF and pro-inflammatory biomarkers, sevelamer carbonate decreased serum endothelin-1, plasminogen activator inhibitor-1, C-reactive protein and interleukin-6. Both phosphate binders were effective in decreasing serum phosphate but sevelamer had a positive effect on EF. Treatment with sevelamer carbonate has beneficial effects compared with calcium carbonate in decreasing inflammation and improving EF in patients with T2DM on PD. © 2013 European Dialysis and Transplant Nurses Association/European Renal Care Association.

Increasing Soil Calcium Availability Alters Forest Soil Carbon Stocks

NASA Astrophysics Data System (ADS)

Melvin, A.; Goodale, C. L.

2011-12-01

Acid deposition in the Northeastern U.S. has been linked to a loss of soil base cations, especially calcium (Ca). While much research has addressed the effects of Ca depletion on soil and stream acidification, few studies have investigated its effects on ecosystem carbon (C) balance. We studied the long-term effects of increased Ca availability on C cycling in a northern hardwood forest in the Adirondack Park, NY. In 1989, calcium carbonate (lime) was added to ~ 100 ha of the Woods Lake Watershed to ameliorate the effects of soil Ca depletion. An additional 100 ha were maintained as controls. We hypothesized that the lime addition would improve forest health and that this improvement would be evident in increased tree biomass, leaf litter, and fine root production. Within the forest floor, we anticipated that the increased pH associated with liming would stimulate microbial activity resulting in increased decomposition and basal soil respiration, and reduced C stocks. Additionally, we hypothesized that increased Ca availability could enhance Ca-OM complexation in the upper mineral soils, leading to increased C stocks in these horizons. Eighteen years after liming, soil pH and exchangeable Ca pools remained elevated in the forest floor and upper mineral soil of the limed plots. Forest floor C stocks were significantly larger in limed plots (68 vs. 31 t C ha-1), and were driven primarily by greater C accumulation in the forest floor Oa horizon. Mineral soil C stocks did not differ between limed and control soils. Liming did not affect tree growth, however a net decline in biomass was observed across the entire watershed. There was a trend for larger fine root and foliar litter inputs in limed plots relative to controls, but the observed forest floor accumulation appears to be driven primarily by a suppression of decomposition. Liming reduced basal soil respiration rates by 17 and 43 % in the Oe and Oa horizons, respectively. This research suggests that Ca may stabilize soil organic matter and that long-term Ca depletion caused by acid deposition could have large, unexpected effects on ecosystem C dynamics.

Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles.

PubMed

Addison, Timothy; Cayre, Olivier J; Biggs, Simon; Armes, Steven P; York, David

2010-05-04

Using a layer-by-layer (LbL) approach, this work presents the preparation of hollow microcapsules with a membrane constructed entirely from a cationic/zwitterionic pair of pH-responsive block copolymer micelles. Our previous work with such systems highlighted that, in order to retain the responsive nature of the individual micelles contained within the multilayer membranes, it is important to optimize the conditions required for the selective dissolution of the sacrificial particulate templates. Consequently, here, calcium carbonate particles have been employed as colloidal templates as they can be easily dissolved in aqueous environments with the addition of chelating agents such as ethylenediaminetetraacetic acid (EDTA). Furthermore, the dissolution can be carried out in solutions buffered to a desirable pH so not to adversely affect the pH sensitive micelles forming the capsule membranes. First, we have deposited alternating layers of anionic poly[2-(dimethylamino)ethyl methacrylate-block-poly(2-(diethylamino)ethyl methacrylate)] (PDMA-PDEA) and cationic poly(2-(diethylamino)ethyl)methacrylate-block-poly(methacrylic acid) (PDEA-PMAA) copolymer micelles onto calcium carbonate colloidal templates. After deposition of five micelle bilayers, addition of dilute EDTA solution resulted in dissolution of the calcium carbonate and formation of hollow polymer capsules. The capsules were imaged using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which shows that the micelle/micelle membrane is sufficiently robust to withstand dissolution of the supporting template. Quartz crystal microbalance studies were conducted and provide good evidence that the micelle multilayer structure is retained after EDTA treatment. In addition, a hydrophobic dye was incorporated into the micelle cores prior to adsorption. After dissolution of the particle template, the resulting hollow capsules retained a high concentration of dye, suggesting that the core/shell structure of the micelles remains intact. Finally, thermogravimetric analysis (TGA) of dried capsules confirmed complete removal of the sacrificial inorganic template. As far as we are aware, this is the first demonstration of LbL assembled capsules composed entirely from responsive block copolymer micelles. The results presented here when combined with our previous findings demonstrate that such systems have potential application in the encapsulation and triggered release of actives.

Comparison study of biomimetic strontium-doped calcium phosphate coatings by electrochemical deposition and air plasma spray: morphology, composition and bioactive performance.

PubMed

Li, Ling; Lu, Xia; Meng, Yizhi; Weyant, Christopher M

2012-10-01

In this study, strontium-doped calcium phosphate coatings were deposited by electrochemical deposition and plasma spray under different process parameters to achieve various coating morphologies. The coating composition was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy while the cytocompatibility and bioactivity of the strontium-doped calcium phosphate coatings were evaluated using bone cell culture using MC3T3-E1 osteoblast-like cells. The addition of strontium leads to enhanced proliferation suggesting the possible benefits of strontium incorporation in calcium phosphate coatings. The morphology and composition of deposited coatings showed a strong influence on the growth of cells.

Development of Bio-Based Foams Prepared from Pbat/Pla Reinforced with Bio-Calcium Carbonate Compatibilized by Electron-Beam Radiation

NASA Astrophysics Data System (ADS)

Cardoso, Elizabeth Carvalho L.; Seixas, Marcus Vinicius S.; Wiebeck, Helio; Oliveira, René R.; Machado, Glauson Aparecido F.; Moura, Esperidiana A. B.

In Brazil, the food industry generates every year huge amounts of avian eggshell waste, an industrial byproduct containing 95% of calcium carbonate, and its disposal constitutes a serious environmental hazard. This study aims to the development of bio-foams from PBAT/PLA blends reinforced with bio-calcium carbonate from eggshells. Composites were obtained by melting extrusion process, blending PBAT/PLA (50/50) with 25% of bio-calcium carbonate, PBAT/PLA (50/45) with 25% of bio-calcium carbonate and 5 % of pre-irradiated PLA and PBAT/PLA (50/40) with 25% of bio-calcium carbonate and 10 % of pre-irradiated PLA. PLA was previously e-beam irradiated at 150kGy in air and used as compatibilizer agent. The composites were then extruded in a Rheomex 332p single special screw for foaming. Samples were submitted to Tensile and Compression tests, MFI, DSC, TGA, XRD and FEG/SEM, analyses.

A facile magnesium-containing calcium carbonate biomaterial as potential bone graft.

PubMed

He, Fupo; Zhang, Jing; Tian, Xiumei; Wu, Shanghua; Chen, Xiaoming

2015-12-01

The calcium carbonate is the main composition of coral which has been widely used as bone graft in clinic. Herein, we readily prepared novel magnesium-containing calcium carbonate biomaterials (MCCs) under the low-temperature conditions based on the dissolution-recrystallization reaction between unstable amorphous calcium carbonate (ACC) and metastable vaterite-type calcium carbonate with water involved. The content of magnesium in MCCs was tailored by adjusting the proportion of ACC starting material that was prepared using magnesium as stabilizer. The phase composition of MCCs with various amounts of magnesium was composed of one, two or three kinds of calcium carbonates (calcite, aragonite, and/or magnesian calcite). The different MCCs differed in topography. The in vitro degradation of MCCs accelerated with increasing amount of introduced magnesium. The MCCs with a certain amount of magnesium not only acquired higher compressive strength, but also promoted in vitro cell proliferation and osteogenic differentiation. Taken together, the facile MCCs shed light on their potential as bone graft. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of Hypergravity on Carbonanhydrase Reactivity in inner Ear Ioncytes of developing Cichlid Fish

NASA Astrophysics Data System (ADS)

Beier, M.; Anken, R.; Rahmann, H.

It has been shown earlier that hypergravity slows down inner ear otolith growth in developing fish. Otolith growth in terms of mineralisation mainly depends on the enzyme carboanhydrase (CAH), which is responsible for the provision of the pH- value necessary for calcium carbonate deposition and thus also is presumed to play a prominent role in Ménière's disease (a sensory - motor disorder inducing vertigo and kinetosis). Larval siblings of cichlid fish (Oreochromis mossambicus) were subjected to hypergravity (3g; 6 hours) during development and separated into normally and kinetotically swimming individuals following the transfer to 1g (i.e., stopping the centrifuge; kinetotically behaving fish performed spinning movements). Subsequently, CAH was histochemically demonstrated in inner ear ionocytes (cells involved in the endolymphatic ion exchange) and enzyme reactivity was determined densitometrically. The results showed that CAH-reactivity was significantly increased in normally behaving hyper-g specimens as compared to controls kept at 1g, whereas no difference in enzyme reactivity was evident between the controls and kinetotically behaving fish. On the background of earlier studies, according to which (1) hypergravity induces a decrease of otolith growth and (2) the otolithic calcium incorporation (visualized using the calcium -tracer alizarin complexone) of kinetotically swimming hyper - g fish was lower as compared to normally behaving hyper - g animals, the present study strongly supports the concept that an increase in CAH-reactivity may result in a decrease of otolithic calcium deposition. The mechanism regulating CAH-activity hitherto remains to be determined. Acknowledgement: This work was financially supported by the German Aerospace Center (DLR) (FKZ: 50 WB 9997).

Environmentally safe oil-field reagents for development and operation of oil-gas deposits

NASA Astrophysics Data System (ADS)

Fakhreeva, A. V.; Manaure, D. A.; Dokichev, V. A.; Voloshin, A. I.; Telin, A. G.; Tomilov, Yu V.; Nifantiev, N. E.

2018-04-01

Sodium-carboxymethylcellulose and arabinogalactane inhibits the crystallization of calcium carbonate from a supersaturated aqueous solution at 80°C. The sizes of formed crystals CaCO3 in the presence of arabinogalactane, sodium-carboxymethylcellulose and neonol AF 9-10 decrease on an average 7-12 μm and a change of their structure. It is expected, that the mechanism of inhibitionis in specific adsorption polysaccharides and neonol on occurring crystalline surface of the calcium carbonate, both at the expense of electrostatic interaction of functional groups with Ca2+ ions, located on the surface of the crystal, and due to coordination and hydrogen bonds with oxygen atoms and HO-groups of additives. Oil-water emulsion rheology in the presence of neonol AF 9-10 has been studied. It is shown that neonol AF 9-10 decrease viscosity natural water-oil emulsion by 25 times. Addition of 5% neonol to water-oil emulsion leads to formation more than 20 stable emulsion forms of different density and composition. New highly effective “green” oilfield reagents have been developed on the basis of neonol and natural polysaccharides.

Calcium-selective electrodes based on photo-cured polyurethane-acrylate membranes covalently attached to methacrylate functionalized poly(3,4-ethylenedioxythiophene) as solid-contact.

PubMed

Ocaña, Cristina; Abramova, Natalia; Bratov, Andrey; Lindfors, Tom; Bobacka, Johan

2018-08-15

We report here the fabrication of solid-contact calcium-selective electrodes (Ca 2+ -SCISEs) made of a polyurethane acrylate ion-selective membrane (ISM) that was covalently attached to the underlying ion-to-electron transducer (solid-contact). Methacrylate-functionalized poly(3,4-ethylenedioxythiophene) (Meth-PEDOT) and Meth-PEDOT films containing either multiwalled carbon nanotubes (MWCNT) or carboxylated MWCNT (cMWCNT) were used as solid contacts. The solid contacts were deposited by drop-casting on screen-printed electrodes and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and potentiometry. Covalent binding between the solid contact and the ISM was obtained via photopolymerization in order to increase the robustness of the Ca 2+ -SCISEs. The performance of the Ca 2+ -SCISEs was studied by measuring their potentiometric response and their sensitivity to light, oxygen and carbon dioxide. Meth-PEDOT was found to be a promising solid-contact material to develop low-cost and easy to prepare ISEs. Copyright © 2018 Elsevier B.V. All rights reserved.

Data set for the proteomic inventory and quantitative analysis of chicken eggshell matrix proteins during the primary events of eggshell mineralization and the active growth phase of calcification.

PubMed

Marie, Pauline; Labas, Valérie; Brionne, Aurélien; Harichaux, Grégoire; Hennequet-Antier, Christelle; Rodriguez-Navarro, Alejandro B; Nys, Yves; Gautron, Joël

2015-09-01

Chicken eggshell is a biomineral composed of 95% calcite calcium carbonate mineral and of 3.5% organic matrix proteins. The assembly of mineral and its structural organization is controlled by its organic matrix. In a recent study [1], we have used quantitative proteomic, bioinformatic and functional analyses to explore the distribution of 216 eggshell matrix proteins at four key stages of shell mineralization defined as: (1) widespread deposition of amorphous calcium carbonate (ACC), (2) ACC transformation into crystalline calcite aggregates, (3) formation of larger calcite crystal units and (4) rapid growth of calcite as columnar structure with preferential crystal orientation. The current article detailed the quantitative analysis performed at the four stages of shell mineralization to determine the proteins which are the most abundant. Additionally, we reported the enriched GO terms and described the presence of 35 antimicrobial proteins equally distributed at all stages to keep the egg free of bacteria and of 81 proteins, the function of which could not be ascribed.

Data set for the proteomic inventory and quantitative analysis of chicken eggshell matrix proteins during the primary events of eggshell mineralization and the active growth phase of calcification

PubMed Central

Marie, Pauline; Labas, Valérie; Brionne, Aurélien; Harichaux, Grégoire; Hennequet-Antier, Christelle; Rodriguez-Navarro, Alejandro B.; Nys, Yves; Gautron, Joël

2015-01-01

Chicken eggshell is a biomineral composed of 95% calcite calcium carbonate mineral and of 3.5% organic matrix proteins. The assembly of mineral and its structural organization is controlled by its organic matrix. In a recent study [1], we have used quantitative proteomic, bioinformatic and functional analyses to explore the distribution of 216 eggshell matrix proteins at four key stages of shell mineralization defined as: (1) widespread deposition of amorphous calcium carbonate (ACC), (2) ACC transformation into crystalline calcite aggregates, (3) formation of larger calcite crystal units and (4) rapid growth of calcite as columnar structure with preferential crystal orientation. The current article detailed the quantitative analysis performed at the four stages of shell mineralization to determine the proteins which are the most abundant. Additionally, we reported the enriched GO terms and described the presence of 35 antimicrobial proteins equally distributed at all stages to keep the egg free of bacteria and of 81 proteins, the function of which could not be ascribed. PMID:26306314

Surface functional group dependent apatite formation on bacterial cellulose microfibrils network in a simulated body fluid.

PubMed

Nge, Thi Thi; Sugiyama, Junji

2007-04-01

The apatite forming ability of biopolymer bacterial cellulose (BC) has been investigated by soaking different BC specimens in a simulated body fluid (1.5 SBF) under physiological conditions, at 37 degrees C and pH 7.4, mimicking the natural process of apatite formation. From ATR-FTIR spectra and ICP-AES analysis, the crystalline phase nucleated on the BC microfibrils surface was calcium deficient carbonated apatite through initial formation of octacalcium phosphate (OCP) or OCP like calcium phosphate phase regardless of the substrates. Morphology of the deposits from SEM, FE-SEM, and TEM observations revealed the fine structure of thin film plates uniting together to form apatite globules of various size (from <1 mum to 3 mum) with respect to the substrates. Surface modification by TEMPO (2,2,6,6-tetramethylpyperidine-1-oxyl)-mediated oxidation, which can readily form active carboxyl functional groups upon selective oxidation of primary hydroxyl groups on the surface of BC microfibrils, enhanced the rate of apatite nucleation. Ion exchanged treatment with calcium chloride solution after TEMPO-mediated oxidation was found to be remarkably different from other BC substrates with the highest deposit weight and the smallest apatite globules size. The role of BC substrates to induce mineralization rate differs according to the nature of the BC substrates, which strongly influences the growth behavior of the apatite crystals. (c) 2006 Wiley Periodicals, Inc.

75 FR 51002 - Pure Magnesium In Granular Form from the People's Republic of China: Initiation of Changed...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-18

.... SUPPLEMENTARY INFORMATION: Background On November 19, 2001, the Department published in the Federal Register an... are: lime, calcium metal, calcium silicon, calcium carbide, calcium carbonate, carbon, slag coagulants, fluorspar, nephaline syenite, feldspar, aluminum, alumina (Al2O3), calcium aluminate, soda ash, hydrocarbons...

Bone response adjacent to calcium phosphate electrostatic spray deposition coated implants: an experimental study in goats.

PubMed

Manders, Peter J D; Wolke, Joop G C; Jansen, John A

2006-10-01

A new technique to deposit calcium phosphate (CaP) coatings onto titanium substrates has been developed recently. This electrostatic spray deposition (ESD) technique seems to be very promising. It appears to have clinical advantages such as an inexpensive and simple set-up, high deposition efficiency and the possibility to synthesize layers with a defined surface morphology. The aim of this study was to examine biological properties and osteoconductivity of ESD CaP coatings when inserted into the femoral condyle of a goat. Twenty-four implants with two gaps, i.e. 1 or 2 mm, were inserted into the femoral condyles of six goats. The implants were coated on one side with either a commercially available plasma-sprayed hydroxyapatite (HAPS) coating or an ESD carbonate apatite (CAESD) coating. The other side of the implant was always left uncoated (Ti). Twelve weeks after implantation the animals were sacrificed and the characteristics of bone ingrowth and bone contact were evaluated. At 3 months, histological and quantitative histomorphometrical measurements demonstrated more bone ingrowth and bone contact for coated sites as compared with uncoated sites. Statistical testing revealed that for both the 1 and 2 mm gaps HAPS (plasma-sprayed hydroxyapatite) as well as CAESD (ESD carbonate apatite) -coated surfaces always had a significantly higher (P<0.05) amount of bone contact than uncoated Ti surfaces. On HAPS surfaces always significantly more bone was present than on CAESD surfaces. Further statistical testing revealed a significant difference in bone ingrowth between the HAPS as well as CAESD and Ti 1+2 mm gap specimens (P<0.05). Further, HAPS 1 mm gaps showed more bone ingrowth than CAESD 1 mm gaps. No significant difference existed between HAPS and CAESD 2 mm gaps. On the basis of our observations, we conclude that the used ESD technique is a promising new method to deposit CaP coatings onto titanium substrates. On the other hand, plasma-spray HA-coated implants have a still more favourable effect on the bone response.

Benthic foraminiferal paleoecology and depositional patterns during the Albian at DSDP Site 327 (Falkland Plateau)

NASA Astrophysics Data System (ADS)

Lopes, Fernando M.; Koutsoukos, Eduardo A. M.; Kochhann, Karlos G. D.; Savian, Jairo F.; Fauth, Gerson

2017-10-01

The present paleoenvironmental study uses a spectrum of analytical methods, such as benthic foraminiferal assemblages, total organic carbon (TOC), calcium carbonate (CaCO3) contents and magnetic susceptibility (MS), to monitor variations in primary productivity, bottom-water oxygenation and depositional patterns within the Albian interval recovered at DSDP Site 327, Hole A, Falkland Plateau. Thirty-three benthic foraminiferal species were identified in the studied section and, based on the abundances of morphogroups (epifaunal and shallow infaunal), two distinct associations were identified. Stratigraphic intervals dominated by the epifaunal morphogroup can be interpreted as indicative of bottom-waters with low-oxygen content. However, these decreases in oxygenation were not vigorous enough to establish a dominance of deep-infaunal morphotypes, as supported by the low TOC values. Intervals dominated by the shallow infaunal morphogroup were interpreted as subjected to moderate to high nutrient flux to the ocean floor. These intervals are associated with high MS values and low CaCO3 content, suggesting that dissolution processes, rather than increased primary productivity, controlled CaCO3 accumulation in the studied section. Furthermore, faunal analysis points to deposition in an outer neritic to upper bathyal paleoenvironment.

Effects of acidic deposition on the erosion of carbonate stone — experimental results from the U.S. National Acid Precipitation Assessment Program (NAPAP)

NASA Astrophysics Data System (ADS)

Baedecker, Philip A.; Reddy, Michael M.; Reimann, Karl J.; Sciammarella, Cesar A.

One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30° to horizontal at the five NAPAP materials exposure sites range from ˜ 15 to ˜ 30 μm yr -1 for marble, and from ˜ 25 to ˜ 45 μm yr -1 for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ˜ 30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ˜ 70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide ("clean rain"). These results are for marble and limestone slabs exposed at an angle of 30° from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60° or 85°. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC, and Steubenville, OH.

Effects of acidic deposition on the erosion of carbonate stone - experimental results from the U.S. National Acid Precipitation Assessment Program (NAPAP)

USGS Publications Warehouse

Baedecker, P.A.; Reddy, M.M.; Reimann, K.J.; Sciammarella, C.A.

1992-01-01

One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30?? to horizontal at the five NAPAP materials exposure sites range from ~15 to ~30?? ??m yr-1 for marble, and from ~25 to ~45 ??m yr -1 for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ~30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ~70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide ('clean rain'). These results are for marble and limestone slabs exposed at an angle of 30?? from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60?? or 85??. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC, and Steubenville, OH.

Preparation of insulin-containing microcapsules by a layer-by-layer deposition of concanavalin A and glycogen.

PubMed

Sato, Katsuhiko; Kodama, Daisuke; Endo, Yoshihiro; Anzai, Jun-ichi

2009-01-01

The sugar sensitive microcapsules were prepared by a layer-by-layer deposition of concanavalin A (Con A) and glycogen on a calcium carbonate particle containing fluorescein-labeled insulin (F-insulin). The Con A/glycogen multilayer capsules were formed through sugar-lectin interactions by using inner and outer poly(ethyleneimine)/poly(vinyl sulfate) multilayers as supports, while without the supports the microcapsules could not be formed. Fluorescent microscope observations revealed that the capsules thus prepared are spherical in shape with 3-10 microm diameter. The microcapsules released encapsulated F-insulin upon addition of sugars. This is because the added sugars replace glycogen in the binding site of Con A, resulting in the enhanced permeability of the microcapsules to insulin.

21 CFR 73.1070 - Calcium carbonate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... mixtures for coloring drugs. (b) Specifications. Calcium carbonate shall meet the specifications for...

21 CFR 73.1070 - Calcium carbonate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF... mixtures for coloring drugs. (b) Specifications. Calcium carbonate shall meet the specifications for...

Inorganic chemical composition and chemical reactivity of settled dust generated by the World Trade Center building collapse: Chapter 12

USGS Publications Warehouse

Plumlee, Geoffrey S.; Hageman, Philip L.; Lamothe, Paul J.; Ziegler, Thomas L.; Meeker, Gregory P.; Theodorakos, Peter M.; Brownfield, Isabelle; Adams, Monique G.; Swayze, Gregg A.; Hoefen, Todd M.; Taggart, Joseph E.; Clark, Roger N.; Wilson, S.; Sutley, Stephen J.

2009-01-01

Samples of dust deposited around lower Manhattan by the September 11, 2001, World Trade Center (WTC) collapse have inorganic chemical compositions that result in part from the variable chemical contributions of concrete, gypsum wallboard, glass fibers, window glass, and other materials contained in the buildings. The dust deposits were also modified chemically by variable interactions with rain water or water used in street washing and fire fighting. Chemical leach tests using deionized water as the extraction fluid show the dust samples can be quite alkaline, due primarily to reactions with calcium hydroxide in concrete particles. Calcium and sulfate are the most soluble components in the dust, but many other elements are also readily leached, including metals such as Al, Sb, Mo Cr, Cu, and Zn. Indoor dust samples produce leachates with higher pH, alkalinity, and dissolved solids than outdoor dust samples, suggesting most outdoor dust had reacted with water and atmospheric carbon dioxide prior to sample collection. Leach tests using simulated lung fluids as the extracting fluid suggest that the dust might also be quite reactive in fluids lining the respiratory tract, resulting in dissolution of some particles and possible precipitation of new phases such as phosphates, carbonates, and silicates. Results of these chemical characterization studies can be used by health scientists as they continue to track and interpret health effects resulting from the short-term exposure to the initial dust cloud and the longer-term exposure to dusts resuspended during cleanup.

[Preparation of polyelectrolyte microcapsules containing ferrosoferric oxide nanoparticles].

PubMed

Liu, Xiao-Qing; Zheng, Chun-Li; Zhu, Jia-Bi

2011-01-01

In this study, polyelectrolyte microcapsules have been fabricated by biocompatible ferrosoferric oxide nanoparticles (Fe3O4 NPs) and poly allyamine hydrochloride (PAH) using layer by layer assembly technique. The Fe3O4 NPs were prepared by chemical co-precipitation, and characterized by transmission electron microscopy (TEM) and infrared spectrum (IR). Quartz cell also was used as a substrate for building multilayer films to evaluate the capability of forming planar film. The result showed that Fe3O4 NPs were selectively deposited on the surface of quartz cell. Microcapsules containing Fe3O4 NPs were fabricated by Fe3O4 NPs and PAH alternately self-assembly on calcium carbonate microparticles firstly, then 0.2 molL(-1) EDTA was used to remove the calcium carbonate. Scanning electron microscopy (SEM), Zetasizer and vibrating sample magnetometer (VSM) were used to characterize the microcapsule's morphology, size and magnetic properties. The result revealed that Fe3O4 NPs and PAH were successfully deposited on the surface of CaCO3 microparticles, the microcapsule manifested superparamagnetism, size and saturation magnetization were 4.9 +/- 1.2 microm and 8.94 emu x g(-1), respectively. As a model drug, Rhodamin B isothiocyanate labeled bovine serum albumin (RBITC-BSA) was encapsulated in microcapsule depended on pH sensitive of the microcapsule film. When pH 5.0, drug add in was 2 mg, the encapsulation efficiency was (86.08 +/- 3.36) % and the drug loading was 8.01 +/- 0.30 mg x m(L-1).

Calcium carbonate gallstones in children.

PubMed

Stringer, Mark D; Soloway, Roger D; Taylor, Donald R; Riyad, Kallingal; Toogood, Giles

2007-10-01

In the United States, cholesterol stones account for 70% to 95% of adult gallstones and black pigment stones for most of the remainder. Calcium carbonate stones are exceptionally rare. A previous analysis of a small number of pediatric gallstones from the north of England showed a remarkably high prevalence of calcium carbonate stones. The aims of this study were to analyze a much larger series of pediatric gallstones from our region and to compare their chemical composition with a series of adult gallstones from the same geographic area. A consecutive series of gallbladder stones from 63 children and 50 adults from the north of England were analyzed in detail using Fourier transform infrared microspectroscopy. Demographic and clinical data were collected on all patients. The relative proportions of each major stone component were assessed: cholesterol, protein and calcium salts of bilirubin, fatty acids, calcium carbonate, and hydroxyapatite. Thirty-nine (78%) adults had typical cholesterol stones, 7 (14%) had black pigment bilirubinate stones, and only 2 (4%) had calcium carbonate stones. In contrast, 30 (48%) children had black pigment stones, 13 (21%) had cholesterol stones, 15 (24%) had calcium carbonate stones, 3 (5%) had protein dominant stones, and 2 (3%) had brown pigment stones. In children, cholesterol stones were more likely in overweight adolescent girls with a family history of gallstones, whereas black pigment stones were equally common in boys and girls and associated with hemolysis, parenteral nutrition, and neonatal abdominal surgery. Calcium carbonate stones were more common in boys, and almost half had undergone neonatal abdominal surgery and/or required neonatal intensive care. The composition of pediatric gallstones differs significantly from that found in adults. In particular, one quarter of the children in this series had calcium carbonate stones, previously considered rare. Geographic differences are not the major reason for the high prevalence of calcium carbonate gallstones in children.

Phytoplankton calcification as an effective mechanism to prevent cellular calcium poisoning

NASA Astrophysics Data System (ADS)

Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

2015-08-01

Marine phytoplankton has developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological time scales. For example, the Cretaceous (145 to 66 Ma ago), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to four times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium-sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to prevent cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations.

Formate oxidation-driven calcium carbonate precipitation by Methylocystis parvus OBBP.

PubMed

Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert; Boon, Nico

2014-08-01

Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such asammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2(-1) calcium carbonate precipitate yield was obtained when a culture of 10(9) cells ml(-1) and 5 g of calcium formate liter(-)1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry.

Formate Oxidation-Driven Calcium Carbonate Precipitation by Methylocystis parvus OBBP

PubMed Central

Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert

2014-01-01

Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such as ammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2−1 calcium carbonate precipitate yield was obtained when a culture of 109 cells ml−1 and 5 g of calcium formate liter−1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry. PMID:24837386

Hypoparathyroidism: what is the best calcium carbonate supplementation intake form?

PubMed

Gollino, Loraine; Biagioni, Maria Fernanda Giovanetti; Sabatini, Nathalia Regina; Tagliarini, José Vicente; Corrente, José Eduardo; Paiva, Sérgio Alberto Rupp de; Mazeto, Gláucia Maria Ferreira da Silva

2017-11-15

In hypoparathyroidism, calcium supplementation using calcium carbonate is necessary for the hypocalcemia control. The best calcium carbonate intake form is unknown, be it associated with feeding, juice or in fasting. The objective was to evaluate the calcium, phosphorus and Calcium×Phosphorus product serum levels of hypoparathyroidism women after total thyroidectomy, following calcium carbonate intake in three different forms. A crossover study was carried out with patients presenting definitive hypoparathyroidism, assessed in different situations (fasting, with water, orange juice, breakfast with a one-week washout). Through the review of clinical data records of tertiary hospital patients from 1994 to 2010, 12 adult women (18 50 years old) were identified and diagnosed with definitive post-thyroidectomy hypoparathyroidism. The laboratory results of calcium and phosphorus serum levels dosed before and every 30min were assessed, for 5h, after calcium carbonate intake (elementary calcium 500mg). The maximum peak average values for calcium, phosphorus and Calcium×Phosphorus product were 8.63mg/dL (water), 8.77mg/dL (orange juice) and 8.95mg/dL (breakfast); 4.04mg/dL (water), 4.03mg/dL (orange juice) and 4.12mg/dL (breakfast); 34.3mg 2 /dL 2 (water), 35.8mg 2 /dL 2 (orange juice) and 34.5mg 2 /dL 2 (breakfast), respectively, and the area under the curve 2433mg/dLmin (water), 2577mg/dLmin (orange juice) and 2506mg/dLmin (breakfast), 1203mg/dLmin (water), 1052mg/dLmin (orange juice) and 1128mg/dLmin (breakfast), respectively. There was no significant difference among the three different tests (p>0.05). The calcium, phosphorus and Calcium×Phosphorus product serum levels evolved in a similar fashion in the three calcium carbonate intake forms. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Comments on the BLAG model: the carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years

NASA Technical Reports Server (NTRS)

Kasting, J. F.

1984-01-01

A self-consistent method of determining initial conditions for the model presented by Berner, Lasaga, and Garrels (1983) (henceforth, the BLAG model) is derived, based on the assumption that the CO2 geochemical cycle was in steady state at t = -100 my (million years). This initialization procedure leads to a dissolved magnesium concentration higher than that calculated by Berner, Lasaga, and Garrels and to a low ratio of dissolved calcium to bicarbonate prior to 60 my ago. The latter prediction conflicts with the geologic record of evaporite deposits, which requires that this ratio remain greater than 0.5. The contradiction is probably caused by oversimplifications in the BLAG model, such as the neglect of the cycles of organic carbon and sulfur.

Comments on the BLAG model - The carbonate-silicate geochemical cycle and its effect on atmospheric carbon dioxide over the past 100 million years

NASA Technical Reports Server (NTRS)

Kasting, J. F.

1984-01-01

A self-consistent method of determining initial conditions for the model presented by Berner, Lasaga, and Garrels (1983) (henceforth, the BLAG model) is derived, based on the assumption that the CO2 geochemical cycle was in steady state at t = -100 m.y. (million years). This initialization procedure leads to a dissolved magnesium concentration higher than that calculated by Berner, Lasaga, and Garrels and to a low ratio of dissolved calcium to bicarbonate prior to 60 m.y. ago. The latter prediction conflicts with the geologic record of evaporite deposits, which requires that this ratio remain greater than 0.5. The contradiction is probably caused by oversimplifications in the BLAG model, such as the neglect of the cycles of organic carbon and sulfur.

Amorphous calcium carbonate associated with biofilms in hot spring deposits

NASA Astrophysics Data System (ADS)

Jones, Brian; Peng, Xiaotong

2012-08-01

Calcium carbonate nanoparticles are intimately associated with crystalline calcite and aragonite in the Eryuan, Gongxiaoshe, and Zhuyuan hot springs (water temperature > 75 °C), which are located in Yunnan Province, China. The nanoparticles, < 1 μm long, are spherical to disc-shaped and commonly fuse together into small clusters. Their general appearance and lack of crystal faces or edges indicate that they are noncrystalline. Morphologically, these nanoparticles are similar to calcified nannobacteria or the constituent grains in amorphous calcium carbonate (ACC), which can be formed by various biogenic and abiogenic processes. In the Chinese hot springs, the ACC is always found under, in, or on top of biofilms, commonly in close proximity to crystalline calcite and/or aragonite. Textural evidence indicates that the ACC probably developed in microdomains that develop in the complex biofilm hydrogels. Critically, there is no evidence to support the notion that the nanoparticles are calcified nannobacteria. In the Chinese springs, ACC appears to play a formative role in the development of wheat-sheaf arrays of aragonite crystals and some of the calcite crystals. Hollow cores in some of the aragonite bundles probably formed as ACC was dissolved and many of the aragonite crystals appear to have developed as ACC recrystallized. Similarly, layers of ACC that coat the surfaces of some calcite crystals could be diagenetically transformed into calcite. The development of ACC in hot spring systems may be widespread and may play a critical but transitory role in the development of crystalline CaCO3 in these high temperature environments.

Bacterially induced precipitation of CaCO 3: An example from studies of cyanobacterial mats. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chafetz, Henry S.

1990-04-30

Bacteria induce the precipitation of calcium carbonate in the laboratory and in nature by altering their chemical environment. Geologists are recognizing the possibility that bacterially induced precipitates may form significant mineral deposits, unfortunately, there are currently no sound criteria by which they can be recognized in recent sediments, or in the rock record. Cultures of aerobic and facultative bacteria from cyanobacterial mats on Andros Island, Bahamas, and Baffin Bay, Texas, induced the precipitation of calcium carbonate under controlled conditions. Crusts, the largest features formed, are composed of 5--200μm diameter bundles which are, in turn, composed of numerous individual crystals. Themore » smallest observed features are 0.1--0.4μm spheres and rods which comprise some individual crystals and crystal bundles. Crystal bundles resembling rhombohedra, tetragonal disphenoids, tetragonal dipyramids, and calcite dumbbells appear to be uniquely bacterial in origin, and they have all been observed in recent sediments. Swollen rods, discs, curved dumbbells, and 50--200μm optically continuous crystals resembling brushes may be uniquely bacterial in origin, however, they have not been reported by other laboratories nor observed in natural settings. Presence of any of these forms in recent sediments should be taken as strong evidence for bacterial influence. Spheres and aragonite dumbbells have also been observed in natural environments, however, they are not always bacterial in origin. Precipitation of calcium carbonate occurs preferentially on dead cyanobacteria in the presence of bacteria. Lithification of algal mats to form stromatolites may take place in the zone of decaying organic matter due to bacterial activity.« less

Bacterially induced precipitation of CaCO sub 3 : An example from studies of cyanobacterial mats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chafetz, H.S.

1990-04-30

Bacteria induce the precipitation of calcium carbonate in the laboratory and in nature by altering their chemical environment. Geologists are recognizing the possibility that bacterially induced precipitates may form significant mineral deposits, unfortunately, there are currently no sound criteria by which they can be recognized in recent sediments, or in the rock record. Cultures of aerobic and facultative bacteria from cyanobacterial mats on Andros Island, Bahamas, and Baffin Bay, Texas, induced the precipitation of calcium carbonate under controlled conditions. Crusts, the largest features formed, are composed of 5--200{mu}m diameter bundles which are, in turn, composed of numerous individual crystals. Themore » smallest observed features are 0.1--0.4{mu}m spheres and rods which comprise some individual crystals and crystal bundles. Crystal bundles resembling rhombohedra, tetragonal disphenoids, tetragonal dipyramids, and calcite dumbbells appear to be uniquely bacterial in origin, and they have all been observed in recent sediments. Swollen rods, discs, curved dumbbells, and 50--200{mu}m optically continuous crystals resembling brushes may be uniquely bacterial in origin, however, they have not been reported by other laboratories nor observed in natural settings. Presence of any of these forms in recent sediments should be taken as strong evidence for bacterial influence. Spheres and aragonite dumbbells have also been observed in natural environments, however, they are not always bacterial in origin. Precipitation of calcium carbonate occurs preferentially on dead cyanobacteria in the presence of bacteria. Lithification of algal mats to form stromatolites may take place in the zone of decaying organic matter due to bacterial activity.« less

Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms.

PubMed

Orr, James C; Fabry, Victoria J; Aumont, Olivier; Bopp, Laurent; Doney, Scott C; Feely, Richard A; Gnanadesikan, Anand; Gruber, Nicolas; Ishida, Akio; Joos, Fortunat; Key, Robert M; Lindsay, Keith; Maier-Reimer, Ernst; Matear, Richard; Monfray, Patrick; Mouchet, Anne; Najjar, Raymond G; Plattner, Gian-Kasper; Rodgers, Keith B; Sabine, Christopher L; Sarmiento, Jorge L; Schlitzer, Reiner; Slater, Richard D; Totterdell, Ian J; Weirig, Marie-France; Yamanaka, Yasuhiro; Yool, Andrew

2005-09-29

Today's surface ocean is saturated with respect to calcium carbonate, but increasing atmospheric carbon dioxide concentrations are reducing ocean pH and carbonate ion concentrations, and thus the level of calcium carbonate saturation. Experimental evidence suggests that if these trends continue, key marine organisms--such as corals and some plankton--will have difficulty maintaining their external calcium carbonate skeletons. Here we use 13 models of the ocean-carbon cycle to assess calcium carbonate saturation under the IS92a 'business-as-usual' scenario for future emissions of anthropogenic carbon dioxide. In our projections, Southern Ocean surface waters will begin to become undersaturated with respect to aragonite, a metastable form of calcium carbonate, by the year 2050. By 2100, this undersaturation could extend throughout the entire Southern Ocean and into the subarctic Pacific Ocean. When live pteropods were exposed to our predicted level of undersaturation during a two-day shipboard experiment, their aragonite shells showed notable dissolution. Our findings indicate that conditions detrimental to high-latitude ecosystems could develop within decades, not centuries as suggested previously.

21 CFR 73.1070 - Calcium carbonate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color...

21 CFR 73.1070 - Calcium carbonate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color...

21 CFR 73.1070 - Calcium carbonate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color...

Instant dentin hypersensitivity relief of a single topical application of an in-office desensitizing paste containing 8% arginine and calcium carbonate: a split-mouth, randomized-controlled study.

PubMed

Kapferer, Ines; Pflug, Claudia; Kisielewsky, Irene; Giesinger, Johannes; Beier, Ulrike S; Dumfahrt, Herbert

2013-01-01

The aim of this study was to evaluate the clinical efficacy of an in-office desensitizing paste containing 8% arginine and calcium carbonate relative to calcium carbonate alone in the reduction of dentin hypersensitivity in a randomized, double-blind, split-mouth clinical trial. Sixty teeth (30 subjects) with an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) were randomly assigned to one of two treatment groups: (1) test paste containing 8% arginine and calcium carbonate (elmex sensitive professional desensitizing paste) and (2) control paste: paris white (calcium carbonate). Tactile and air blast dentin hypersensitivity examinations were performed at baseline, immediately after paste application and 4 and 12 weeks later. A statistically significant difference in air blast (p = 0.001) and tactile (p = 0.047) hypersensitivity reduction over time was observed between the two therapy modes. After 12-weeks, statistically significant differences were indicated between the test and control group with respect to baseline-adjusted mean tactile (41.94%; p = 0.038) and air blast hypersensitivity scores (46.5%; p = 0.017). The tested in-office desensitizing paste containing 8.0% arginine and calcium carbonate provides significantly greater hypersensitivity relief compared to calcium carbonate alone.

21 CFR 181.29 - Stabilizers.

Code of Federal Regulations, 2012 CFR

2012-04-01

... glycerophosphate. Calcium phosphate. Calcium hydrogen phosphate. Calcium oleate. Calcium acetate. Calcium carbonate. Calcium ricinoleate. Calcium stearate. Disodium hydrogen phosphate. Magnesium glycerophosphate. Magnesium...

21 CFR 181.29 - Stabilizers.

Code of Federal Regulations, 2010 CFR

2010-04-01

... glycerophosphate. Calcium phosphate. Calcium hydrogen phosphate. Calcium oleate. Calcium acetate. Calcium carbonate. Calcium ricinoleate. Calcium stearate. Disodium hydrogen phosphate. Magnesium glycerophosphate. Magnesium...

21 CFR 181.29 - Stabilizers.

Code of Federal Regulations, 2011 CFR

2011-04-01

... glycerophosphate. Calcium phosphate. Calcium hydrogen phosphate. Calcium oleate. Calcium acetate. Calcium carbonate. Calcium ricinoleate. Calcium stearate. Disodium hydrogen phosphate. Magnesium glycerophosphate. Magnesium...

21 CFR 181.29 - Stabilizers.

Code of Federal Regulations, 2013 CFR

2013-04-01

... glycerophosphate. Calcium phosphate. Calcium hydrogen phosphate. Calcium oleate. Calcium acetate. Calcium carbonate. Calcium ricinoleate. Calcium stearate. Disodium hydrogen phosphate. Magnesium glycerophosphate. Magnesium...

Palladium Nanoparticles Immobilized on Individual Calcium Carbonate Plates Derived from Mussel Shell Waste: An Ecofriendly Catalyst for the Copper-Free Sonogashira Coupling Reaction.

PubMed

Saetan, Trin; Lertvachirapaiboon, Chutiparn; Ekgasit, Sanong; Sukwattanasinitt, Mongkol; Wacharasindhu, Sumrit

2017-09-05

The conversion of waste into high-value materials is considered an important sustainability strategy in modern chemical industries. A large volume of shell waste is generated globally from mussel cultivation. In this work, mussel shell waste (Perna viridis) is transformed into individual calcium carbonate plates (ICCPs) and is applied as a support for a heterogeneous catalyst. Palladium nanoparticles (3-6 nm) are deposited with an even dispersion on the ICCP surface, as demonstrated by X-ray diffraction and scanning electron microscopy. Using this system, Sonogashira cross-coupling reactions between aryl iodides and terminal acetylenes were accomplished in high yields with the use of 1 % Pd/ICCP in the presence of potassium carbonate without the use of any copper metal or external ligand. The Pd/ICCP catalyst could also be reused up to three times and activity over 90 % was maintained with negligible Pd-metal leaching. This work demonstrates that mussel shell waste can be used as an inexpensive and effective support for metal catalysts in coupling reactions, as demonstrated by the successful performance of the Pd-catalyzed, copper-free Sonogashira cross-coupling process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deposition of phosphate coatings on titanium within scaffold structure.

PubMed

Trybuś, Bartłomiej; Zieliński, Andrzej; Beutner, Rene; Seramak, Tomasz; Scharnweber, Dieter

2017-01-01

Existing knowledge about the appearance, thickness, and chemical composition of phosphate coatings on titanium inside porous structures is insufficient. Such knowledge is important for the design and fabrication of porous implants. Metallic scaffolds were fabricated by selective laser melting of 316L stainless steel powder. Phosphate coatings were deposited on Ti sensors placed either outside the scaffolds or in the holes in the scaffolds. The electrochemically-assisted cathodic deposition of phosphate coatings was performed under galvanostatic conditions in an electrolyte containing the calcium and phosphate ions. The phosphate deposits were microscopically investigated; this included the performance of mass weight measurements and chemical analyses of the content of Ca2+ and  24 PO ions after the dissolution of deposits. The thicknesses of the calcium phosphate coatings were about 140 and 200 nm for isolated titanium sensors and 170 and 300 nm for titanium sensors placed inside pores. Deposition of calcium phosphate occurred inside the pores up to 150 mm below the scaffold surface. The deposits were rich in Ca, with a Ca/P ratio ranging from 2 to 2.5. Calcium phosphate coatings can be successfully deposited on a Ti surface inside a model scaffold. An increase in cathodic current results in an increase in coating thickness. Any decrease in the cathodic current inside the porous structure is slight. The calcium phosphate inside the pores has a much higher Ca/P ratio than that of stoichiometric HAp, likely due to a gradual increase in Ca fraction with distance from the surface.

Comparative Ultrastructure and Carbohydrate Composition of Gastroliths from Astacidae, Cambaridae and Parastacidae Freshwater Crayfish (Crustacea, Decapoda)

PubMed Central

Luquet, Gilles; Fernández, María S.; Badou, Aïcha; Guichard, Nathalie; Roy, Nathalie Le; Corneillat, Marion; Alcaraz, Gérard; Arias, José L.

2012-01-01

Crustaceans have to cyclically replace their rigid exoskeleton in order to grow.Most of them harden this skeleton by a calcification process. Some decapods (land crabs, lobsters and crayfish) elaborate calcium storage structures as a reservoir of calcium ions in their stomach wall, as so-called gastroliths. For a better understanding of the cyclic elaboration of these calcium deposits, we studied the ultrastructure of gastroliths from freshwater crayfish by using a combination of microscopic and physical techniques. Because sugars are also molecules putatively involved in the elaboration process of these biomineralizations, we also determined their carbohydrate composition. This study was performed in a comparative perspective on crayfish species belonging to the infra-order Astacidea (Decapoda, Malacostraca): three species from the Astacoidea superfamily and one species from the Parastacoidea superfamily. We observed that all the gastroliths exhibit a similar dense network of protein-chitin fibers, from macro- to nanoscale, within which calcium is precipitated as amorphous calcium carbonate. Nevertheless, they are not very similar at the molecular level, notably as regards their carbohydrate composition. Besides glucosamine, the basic carbohydrate component of chitin, we evidenced the presence of other sugars, some of which are species-specific like rhamnose and galacturonic acid whereas xylose and mannose could be linked to proteoglycan components. PMID:24970155

Optimisation of entrapped activated carbon conditions to remove coloured compounds from winery wastewaters.

PubMed

Devesa-Rey, R; Bustos, G; Cruz, J M; Moldes, A B

2011-06-01

The objective of this work was to study the entrapped conditions of activated carbon in calcium-alginate beads for the clarification of winery wastewaters. An incomplete 3(3) factorial design was carried out to study the efficiency of activated carbon (0.5-2%); sodium alginate (1-5%); and calcium chloride (0.050-0.900 M), on the following dependent variables: colour reduction at 280, 465, 530 and 665 nm. The activated carbon and calcium chloride were the most influential variables in the colour reduction. Nearly 100% colour reductions were found for the wavelengths assayed when employing 2% of activated carbon, 5% of sodium alginate and intermediate concentrations of calcium chloride (0.475 M). Instead, other conditions like, 2% of activated carbon, 4% of sodium alginate and 0.580 M of calcium chloride can also give absorbance reductions close to 100%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Gas/solid carbon branching ratios in surface-mediated reactions and the incorporation of carbonaceous material into planetesimals

PubMed Central

Nuth, Joseph A.; Johnson, Natasha M.; Ferguson, Frank T.; Carayon, Alicia

2018-01-01

We report the ratio of the initial carbon available as CO that forms gas-phase compounds compared to the fraction that deposits as a carbonaceous solid (the gas/solid branching ratio) as a function of time and temperature for iron, magnetite, and amorphous iron silicate smoke catalysts during surface-mediated reactions in an excess of hydrogen and in the presence of N2. This fraction varies from more than 99% for an amorphous iron silicate smoke at 673 K to less than 40% for a magnetite catalyst at 873 K. The CO not converted into solids primarily forms methane, ethane, water, and CO2, as well as a very wide range of organic molecules at very low concentration. Carbon deposits do not form continuous coatings on the catalytic surfaces, but instead form extremely high surface area per unit volume “filamentous” structures. While these structures will likely form more slowly but over much longer times in protostellar nebulae than in our experiments due to the much lower partial pressure of CO, such fluffy coatings on the surfaces of chondrules or calcium aluminum inclusions could promote grain–grain sticking during low-velocity collisions. PMID:29563766

Gas/Solid Carbon Branching Ratios in Surface Mediated Reactions and the Incorporation of Carbonaceous Material into Planetesimals

NASA Technical Reports Server (NTRS)

Nuth, Joseph A.; Johnson, Natasha M.; Ferguson, Frank T.; Carayon, Alicia

2016-01-01

We report the ratio of the initial carbon available as CO that forms gas-phase compounds compared to the fraction that deposits as a carbonaceous solid (the gas solid branching ratio) as a function of time and temperature for iron, magnetite, and amorphous iron silicate smoke catalysts during surface-mediated reactions in an excess of hydrogen and in the presence of N2. This fraction varies from more than 99 for an amorphous iron silicate smoke at 673 K to less than 40% for a magnetite catalyst at 873 K. The CO not converted into solids primarily forms methane, ethane, water, and CO2, as well as a very wide range of organic molecules at very low concentration. Carbon deposits do not form continuous coatings on the catalytic surfaces, but instead form extremely high surface area per unit volume filamentous structures. While these structures will likely form more slowly but over much longer times in protostellar nebulae than in our experiments due to the much lower partial pressure of CO, such fluffy coatings on the surfaces of chondrules or calcium aluminum inclusions could promote grain-grain sticking during low-velocity collisions.

Deposition of Boron in Possible Evaporite Deposits in Gale Crate

NASA Astrophysics Data System (ADS)

Gasda, P. J.; Peets, E.; Lamm, S. N.; Rapin, W.; Lanza, N.; Frydenvang, J.; Clark, B. C.; Herkenhoff, K. E.; Bridges, J.; Schwenzer, S. P.; Haldeman, E. B.; Wiens, R. C.; Maurice, S.; Clegg, S. M.; Delapp, D.; Sanford, V.; Bodine, M. R.; McInroy, R.

2017-12-01

Boron has been previously detected in Gale crater using the ChemCam instrument on board the NASA Curiosity rover within calcium sulfate fracture fill hosted by lacustrine mudstone and eolian sandstone units. Recent results show that up to 300 ppm B is present in the upper sections of the lacustrine unit. Boron has been detected in both the groundwater-emplaced calcium sulfate fracture fill materials and bedding-parallel calcium sulfate layers. The widespread bedding-parallel calcium sulfate layers within the upper strata of the lacustrine bedrock that Curiosity has encountered recently could be interpreted as primary evaporite deposits. We have two hypotheses for the history of boron in Gale crater. In both hypotheses, borates were first deposited as lake water evaporated, depositing primary evaporates that were later re-dissolved by groundwater, which redistributed the boron into secondary evaporitic calcium sulfate fracture fill deposits. In the first scenario, Gale crater may have undergone a period of perennial lake formation during a drier period of martian history, depositing layers of evaporitic minerals (including borates) among lacustrine mudstone layers. In the second scenario, lake margins could have become periodically exposed during cyclic drops in lake level and subsequently desiccated. Evaporites were deposited and desiccation features were formed in lowstand deposits. Either hypothetical scenario of evaporite deposition would promote prebiotic chemical reactions via wet-dry cycles. Boron may be an important prebiotic element, and as such, its presence in ancient martian surface and groundwater provides evidence that important prebiotic chemical reactions could occur on Mars if organics were present. The presence of boron in ancient Gale crater groundwater also provides additional evidence that a habitable environment existed in the martian subsurface well after the expected disappearance of liquid water on the surface of Mars. We will report on the most recent results for boron in relation to these bedding-parallel calcium sulfate layers and lowstand deposits. If a connection between observations of boron and lowstand lake features is found, this would suggest the existence of boron-bearing lake-deposited evaporites in Gale.

Factors that influence properties of FOG deposits and their formation in sewer collection systems.

PubMed

Iasmin, Mahbuba; Dean, Lisa O; Lappi, Simon E; Ducoste, Joel J

2014-02-01

Understanding the formation of Fat, Oil, and Grease (FOG) deposits in sewer systems is critical to the sustainability of sewer collection systems since they have been implicated in causing sewerage blockages that leads to sanitary sewer overflows (SSOs). Recently, FOG deposits in sewer systems displayed strong similarities with calcium-based fatty acid salts as a result of a saponification reaction. The objective of this study was to quantify the factors that may affect the formation of FOG deposits and their chemical and rheological properties. These factors included the types of fats used in FSEs, environmental conditions (i.e. pH and temperature), and the source of calcium in sewer systems. The results of this study showed that calcium content in the calcium based salts seemed to depend on the solubility limit of the calcium source and influenced by pH and temperature conditions. The fatty acid profile of the calcium-based fatty acid salts produced under alkali driven hydrolysis were identical to the profile of the fat source and did not match the profile of field FOG deposits, which displayed a high fraction of palmitic, a long chain saturated fatty acid. It is hypothesized that selective microbial metabolism of fats and/or biologically induced hydrogenation may contribute to the FOG deposit makeup in sewer system. Therefore, selective removal of palmitic in pretreatment processes may be necessary prior to the discharge of FSE wastes into the sewer collection system. Copyright © 2013 Elsevier Ltd. All rights reserved.

The erosion of carbonate stone by acid rain: Laboratory and field investigations

USGS Publications Warehouse

Baedecker, P.A.; Reddy, M.M.

1993-01-01

One of the goals of research on the effects of acidic deposition on carbonate stone surfaces is to define the incremental impact of acidic deposition relative to natural weathering processes on the rate of carbonate stone erosion. If rain that impacts carbonate stone surfaces is resident on the surface long enough to approach chemical equilibrium, the incremental effect of hydrogen ion is expected to be small (i.e., 6% for a rain of pH 4.0). Under nonequilibrium (i.e., high flow rate) conditions, kinetic considerations suggest that the incremental effect of hydrogen ion deposition could be quite significant. Field run-off experiments involving the chemical analysis of rain collected from inclined stone slabs have been used to evaluate stone dissolution processes under ambient conditions of wet and dry deposition of acidic species. The stoichiometry of the reaction of stone with hydrogen ion is difficult to define from the field data due to scatter in the data attributed to hydrodynamic effects. Laboratory run-off experiments show that the stoichiometry is best defined by a reaction with H+ in which CO2 is released from the system. The baseline effect caused by water in equilibrium with atmospheric CO2 is identical in the field and in laboratory simulation. The experiments show that the solutions are close enough to equilibrium for the incremental effect of hydrogen ion to be minor (i.e., 24% for marble for a rain of pH 4.0) relative to dissolution due to water and carbonic acid reactions. Stone erosion rates based on physical measurement are approximately double the recession rates that are due to dissolution (estimated from the observed calcium content of the run-off solutions). The difference may reflect the loss of granular material not included in recession estimates based on the run-off data. Neither the field nor the laboratory run-off experiments indicate a pH dependence for the grain-removal process.

The formation of web-like connection among electrospun chitosan/PVA fiber network by the reinforcement of ellipsoidal calcium carbonate.

PubMed

Sambudi, Nonni Soraya; Kim, Minjeong G; Park, Seung Bin

2016-03-01

The electrospun fibers consist of backbone fibers and nano-branch network are synthesized by loading of ellipsoidal calcium carbonate in the mixture of chitosan/poly(vinyl alcohol) (PVA) followed by electrospinning. The synthesized ellipsoidal calcium carbonate is in submicron size (730.7±152.4 nm for long axis and 212.6±51.3 nm for short axis). The electrospun backbone fibers experience an increasing in diameter by loading of calcium carbonate from 71.5±23.4 nm to 281.9±51.2 nm. The diameters of branch fibers in the web-network range from 15 nm to 65 nm with most distributions of fibers are in 30-35 nm. Calcium carbonate acts as reinforcing agent to improve the mechanical properties of fibers. The optimum value of Young's modulus is found at the incorporation of 3 wt.% of calcium carbonate in chitosan/PVA fibers, which is enhanced from 15.7±3 MPa to 432.4±94.3 MPa. On the other hand, the ultimate stress of fibers experiences a decrease. This result shows that the fiber network undergoes changes from flexible to more stiff by the inclusion of calcium carbonate. The thermal analysis results show that the crystallinity of polymer is changed by the existence of calcium carbonate in the fiber network. The immersion of fibers in simulated body fluid (SBF) results in the formation of apatite on the surface of fibers. Copyright © 2015 Elsevier B.V. All rights reserved.

Prostaglandin PGE2: a possible mechanism for bone destruction in calcinosis circumscripta.

PubMed

Caniggia, A; Gennari, C; Vattimo, A; Runci, F; Bombardieri, S

1978-02-28

A patient showed evident osteolysis in phalanges and heavy periarticular calcium deposits of the fingers, wrists and toes which avidly took up 47Ca. The dense, white, tooth-paste like fluid contained in the periarticular calcium deposits has been studied by two different X-ray diffraction methods, by Ubatuba's bioassay for prostaglandin, by thin layer chromatography and by mass spectrometry. The calcium deposits were hydroxyapatite and prostaglandin PGE2 was detected in them. The bone resorption stimulating activity of PGE2 would be expected to result in increased bone destruction with release of calcium salts and this could be a working hypothesis of the pathogenesis of calcinosis circumscripta.

Vibrational investigation of calcium-silicate cements for endodontics in simulated body fluids

NASA Astrophysics Data System (ADS)

Taddei, Paola; Modena, Enrico; Tinti, Anna; Siboni, Francesco; Prati, Carlo; Gandolfi, Maria Giovanna

2011-05-01

Calcium-silicate MTA (Mineral Trioxide Aggregate) cements have been recently developed for oral and endodontic surgery. This study was aimed at investigating commercial (White ProRoot MTA, White and Grey MTA-Angelus) and experimental (wTC-Bi) accelerated calcium-silicate cements with regards to composition, hydration products and bioactivity upon incubation for 1-28 days at 37 °C, in Dulbecco's Phosphate Buffered Saline (DPBS). Deposits on the surface of the cements and the composition changes during incubation were investigated by micro-Raman and ATR/FT-IR spectroscopy, and pH measurements. Vibrational techniques disclosed significant differences in composition among the unhydrated cements, which significantly affected the bioactivity as well as pH, and hydration products of the cements. After one day in DPBS, all the cements were covered by a more or less homogeneous layer of B-type carbonated apatite. The experimental cement maintained a high bioactivity, only slightly lower than the other cements and appears a valid alternative to commercial cements, in view of its adequate setting time properties. The bioactivity represents an essential property to favour bone healing and makes the calcium-silicate cements the gold standard materials for root-apical endodontic surgery.

Calcium Carbonate Crystal Growth in Porous Media, in the presence of Water Miscible and Non-Miscible Organic Fluids

NASA Astrophysics Data System (ADS)

Jaho, Sofia; Sygouni, Varvara; Paraskeva, Christakis A.

2015-04-01

The deposition of sparingly soluble salts (scaling) within porous media is a major problem encountered in many industrial and environmental applications. In the oil industry scaling causes severe operational malfunctions and, therefore, increasing the total operating and maintenance cost [1]. The most common types of sparingly soluble salts located in oil fields include carbonate and sulfate salts of calcium, strondium and barium[1,2]. Multiple phase flow and tubing surface properties are some of the factors affecting scale formation [3]. The main purpose of the present work was the investigation of the precipitation mechanisms of calcium carbonate (CaCO3) through in situ mixing of two soluble salt solutions in a flow granular medium, in the presence of water miscible organic fluid (ethylene glycol) or non-miscible organic fluid (n-dodecane). All series of experiments were carried out in a two dimensional porous medium made of Plexiglas. For all solutions used in the experiments, the contact angles with the surface of the porous medium and the interfacial tensions were measured. During the experiments, the calcium carbonate crystal growth was continuously monitored and recorded through an optical microscope equipped with a digital programmed video camera. The snap-shots were taken within specific time intervals and their detailed procession gave information concerning the crystal growth rate and kinetics. The pH of the effluent was measured and fluids samples were collected for calcium analysis using Atomic Absorption Spectroscopy (AAS). In all experiments effluent calcium concentration decreased as a function of time, suggesting that CaCO3 precipitation took place inside the porous medium. Crystals of the precipitated salt were identified using Infrared Spectroscopy (IR) and the morphology of the crystals was examined using Scanning Electron Microscopy (SEM). The induction time for precipitation of CaCO3 crystals in the presence of n-dodecane was significantly reduced compared to the induction time where no oil phase was present. The interface of n-dodecane and supersaturated solutions seems to be very active and favored the formation of the CaCO3 crystalline enhancing the heterogeneous nucleation which generally demands a decreased energy barrier. Acknowledgments This research was partially funded by the European Union (European Social Fund-ESF) and Greek National Funds through the Operational Program "Education and Lifelong Learning" under the action Aristeia II (Code No4420). References 1. Merdhah A. B. and Yassin A. A., Scale formation in oil reservoir during water injection at high-salinity formation water, Journal of Applied Sciences, 7, 3198-3207 (2007). 2. Moghadasi J., Muller-Steinhagen H., Jamialahmadi M. and Sharif A., Model study on the kinetics of oil field formation damage due to salt precipitation from injection, Journal of Petroleum Science and Engineering, 43, 201-217 (2004). 3. Nancollas G. H. and Reddy M. M., The crystallization of calcium carbonate II. Calcite growth mechanism, Journal of Colloid and Interface Science, 37, 824-830 (1971).

U.S. Geological Survey Karst Interest Group Proceedings, Bowling Green, Kentucky, May 27-29, 2008

USGS Publications Warehouse

Kuniansky, Eve L.

2008-01-01

*INTRODUCTION AND ACKNOWLEDGMENTS* Karst aquifer systems are present throughout parts of the United States and some of its territories. The complex depositional environments that form carbonate rocks combined with post-depositional tectonic events and the diverse climatic regimes under which these rocks were formed result in unique hydrologic systems. The dissolution of calcium carbonate and the subsequent development of distinct and beautiful landscapes, caverns, and springs have resulted in some karst areas of the United States being designated as national or state parks and commercial caverns. Karst aquifers and landscapes that form in tropical areas, such as the north coast of Puerto Rico, differ greatly from karst areas in more arid climates, such as central Texas or western South Dakota. Many of these public and private lands contain unique flora and fauna associated with the hydrologic systems in these karst areas. As a result, multiple Federal, State, and local agencies have an interest in the study of karst terrains. Carbonate sediments and rocks (limestone and dolomite) are composed of greater than 50 percent carbonate minerals and the predominant carbonate mineral is calcium carbonate or limestone (CaCO3). Unlike terrigenous clastic sedimentation, the depositional processes that produce carbonate rocks are complex, involving both biological and physical processes. These depositional processes impact greatly the development of permeability of the sediments. Carbonate minerals readily dissolve or precipitate depending on the chemistry of the water flowing through the rock, thus the study of both marine and meteoric diagenesis of carbonate sediments is multidisciplinary. Even with a better understanding of the depositional environment and subsequent diagenesis, the dual porosity nature of karst aquifers presents challenges to scientists attempting to study ground-water flow and contaminant transport. Many of the major springs and aquifers in the United States are developed in carbonate rocks and karst areas. These aquifers and the springs that discharge from them, serve as major water-supply sources and as unique biological habitats. Commonly, there is competition for the water resources of karst aquifers, and urban development in karst areas can impact the ecosystem and water quality of these aquifers. The concept for developing a Karst Interest Group evolved from the November 1999 National Ground-Water Meeting of the U.S. Geological Survey (USGS), Water Resources Division. As a result, the Karst Interest Group was formed in 2000. The Karst Interest Group is a loose-knit grass-roots organization of USGS employees devoted to fostering better communication among scientists working on, or interested in, karst hydrology studies. The mission of the Karst Interest Group is to encourage and support interdisciplinary collaboration and technology transfer among USGS scientists working in karst areas. Additionally, the Karst Interest Group encourages cooperative studies between the different disciplines of the USGS and other Department of Interior agencies and university researchers or research institutes. The first Karst Interest Group workshop was held in St. Petersburg, Florida, February 13-16, 2001, in the vicinity of karst features of the Floridan aquifer system. The proceedings of that first meeting, Water-Resources Investigations Report 01-4011 are available online at: http://water.usgs.gov/ogw/karst/ The second Karst Interest Group workshop was held August 20-22, 2002, in Shepherdstown, West Virginia, in close proximity to the carbonate aquifers of the northern Shenandoah Valley. The proceedings of the second workshop were published in Water-Resources Investigations Report 02-4174, which is available online at the previously mentioned website. The third workshop of the Karst Interest Group was held September, 12-15, 2005, in Rapid City, South Dakota, which is in close proximity to karst features

75 FR 52989 - Specialty Minerals, Inc., Franklin, VA; Notice of Negative Determination Regarding Application...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-30

... Register on July 1, 2010 (75 FR 38142). The workers produced precipitated calcium carbonate used in the... precipitated calcium carbonate from the subject firm to a foreign country; nor was there any increase in imports of articles like or directly competitive with precipitated calcium carbonate produced at the...

Biomineralization processes of calcite induced by bacteria isolated from marine sediments

PubMed Central

Wei, Shiping; Cui, Hongpeng; Jiang, Zhenglong; Liu, Hao; He, Hao; Fang, Nianqiao

2015-01-01

Biomineralization is a known natural phenomenon associated with a wide range of bacterial species. Bacterial-induced calcium carbonate precipitation by marine isolates was investigated in this study. Three genera of ureolytic bacteria, Sporosarcina sp., Bacillus sp. and Brevundimonas sp. were observed to precipitate calcium carbonate minerals. Of these species, Sporosarcina sp. dominated the cultured isolates. B. lentus CP28 generated higher urease activity and facilitated more efficient precipitation of calcium carbonate at 3.24 ± 0.25 × 10−4 mg/cell. X-ray diffraction indicated that the dominant calcium carbonate phase was calcite. Scanning electron microscopy showed that morphologies of the minerals were dominated by cubic, rhombic and polygonal plate-like crystals. The dynamic process of microbial calcium carbonate precipitation revealed that B. lentus CP28 precipitated calcite crystals through the enzymatic hydrolysis of urea, and that when ammonium ion concentrations reached 746 mM and the pH reached 9.6, that favored calcite precipitation at a higher level of 96 mg/L. The results of this research provide evidence that a variety of marine bacteria can induce calcium carbonate precipitation, and may influence the marine carbonate cycle in natural environments. PMID:26273260

Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

PubMed

Islam, Aminul; Teo, Siow Hwa; Rahman, M Aminur; Taufiq-Yap, Yun Hin

2015-01-01

A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.

Seeded Growth Route to Noble Calcium Carbonate Nanocrystal

PubMed Central

Islam, Aminul; Teo, Siow Hwa; Rahman, M. Aminur; Taufiq-Yap, Yun Hin

2015-01-01

A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33–41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed. PMID:26700479

Calcium overloading in traumatic axonal injury by lateral head rotation: a morphological evidence in rat model.

PubMed

He, Xiao-Sheng; Xiang, Zhang; Zhou, Fei; Fu, Luo-An; Shuang, Wang

2004-05-01

The study investigated morphologically axonal calcium overloading and its relationship with axonal structural changes. Twelve SD rats were divided into an injury and a sham group. The rat model of traumatic axonal injury (TAI) by lateral head rotation was produced. The oxalate-pyroantimonate technique for calcium localization was used to process the rat's medulla oblongata tissues with thin sections observed electron-microscopically for axonal structure and calcium precipitates on it. The axonal damage in medulla oblongata appeared at 2 h post-injury, gradually became diffuse and severe, and continued to exist at 24 hours. At 2 hours, calcium precipitates were deposited on separated lamellae and axolemma, but were rarely distributed in the axoplasm. At 6 hours, calcium precipitates occurred on separated lamellae and axolemma in much higher density, but on axoplasm in extremely small amounts. Some axons, though lacking structural changes of the myelin sheath, sequestered plenty of calcium deposits on their swollen mitochondria. At 24 hours, damaged axons presented with much more severe lamellae separation and calcium deposits. Axonal calcium overloading developed in rat TAI model using lateral head rotation. This was significantly related to structural damage in the axons. These findings suggest the feasibility of using calcium antagonists in cope the management of human DAI in its very early stage.

77 FR 63787 - Pure Magnesium in Granular Form from the People's Republic of China: Continuation of Antidumping...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-17

... (202) 482-0414, respectively. SUPPLEMENTARY INFORMATION: On February 1, 2012, the Department initiated... aware used to make such excluded reagents are: Lime, calcium metal, calcium silicon, calcium carbide, calcium carbonate, carbon, slag coagulants, fluorspar, nephaline syenite, feldspar, aluminum, alumina...

77 FR 46030 - Pure Magnesium in Granular Form From the People's Republic of China: Preliminary Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-02

... Street and Constitution Avenue NW., Washington, DC 20230; telephone: (202) 482-6231. SUPPLEMENTARY... Department is aware used to make such excluded reagents are: Lime, calcium metal, calcium silicon, calcium carbide, calcium carbonate, carbon, slag coagulants, fluorspar, nephaline syenite, feldspar, aluminum...

Characterization of the Lower Wolfcamp, Midland Basin, Texas, using subsurface stratigraphic and geochemical datasets.

NASA Astrophysics Data System (ADS)

Perlman, Z. S.; Ryan, P. T.; Baldwin, P.; Lucas, J.; McGlue, M. M.; Waite, L.; Woodruff, O. P.

2016-12-01

In recent years, the Midland Basin of west Texas has resurfaced as a strong and viable unconventional oil field, especially within the late Pennsylvanian-Early Permian section. In addition to exploring for hydrocarbons, studying this basin allows for a better understanding of the paleoceanographic and paleoenvironmental conditions that prevailed during deposition. This research focuses on subsurface data from the Lower Wolfcamp interval of the northern Midland Basin proximal to the Horseshoe Atoll. Chemostratigraphic and lithostratigraphic analyses were conducted on 388 ft of continuous drill core extracted from Martin County, Texas. Comprehensive analyses revealed repetitive stacking of organic-rich siliceous mudrocks, aluminum-rich clayey mudrocks, and diverse carbonate facies. High resolution energy dispersive X-ray fluorescence data demonstrate cyclic variability in silicon, aluminum, and calcium weight percentages. These data suggest that during the time of deposition, the Midland Basin was a mixed siliciclastic-carbonate system influenced by a global icehouse climate with high frequency glacio-eustatic sea level fluctuations. Organic carbon preservation at this time was at least partially influenced by bottom water redox conditions. Elemental trace metal data suggests the potential for anoxia and possibly euxinia, likely influenced by recharge from the Panthalassic Ocean. Stratal evidence for bottom water conditions and patterns of organic enrichment vary across the basin and in vertical succession; these factors may be explained by evolving oceanographic processes and environmental gradients within the basin. The timing of Lower Wolfcamp deposition may be Late Pennsylvanian, based on correlations to fusulinids in shelfal carbonates. Thus, our preliminary interpretations focus on Lower Wolfcamp strata as a condensed package of deep-basin cyclothems.

Randomized crossover study comparing the phosphate-binding efficacy of calcium ketoglutarate versus calcium carbonate in patients on chronic hemodialysis.

PubMed

Bro, S; Rasmussen, R A; Handberg, J; Olgaard, K; Feldt-Rasmussen, B

1998-02-01

The objective of the study was to evaluate the phosphate-binding efficacy, side effects, and cost of therapy of calcium ketoglutarate granulate as compared with calcium carbonate tablets in patients on chronic hemodialysis. The study design used was a randomized, crossover open trial, and the main outcome measurements were plasma ionized calcium levels, plasma phosphate levels, plasma intact parathyroid hormone (PTH) levels, requirements for supplemental aluminum-aminoacetate therapy, patient tolerance, and cost of therapy. Nineteen patients on chronic hemodialysis were treated with a dialysate calcium concentration of 1.25 mmol/L and a fixed alfacalcidol dose for at least 2 months. All had previously tolerated therapy with calcium carbonate. Of the 19 patients included, 10 completed both treatment arms. After 12 weeks of therapy, the mean (+/-SEM) plasma ionized calcium level was significantly lower in the ketoglutarate arm compared with the calcium carbonate arm (4.8+/-0.1 mg/dL v 5.2+/-0.1 mg/dL; P = 0.004), whereas the mean plasma phosphate (4.5+/-0.3 mg/dL v 5.1+/-0.1 mg/dL) and PTH levels (266+/-125 pg/mL v 301+/-148 pg/mL) did not differ significantly between the two treatment arms. Supplemental aluminum-aminoacetate was not required during calcium ketoglutarate treatment, while two patients needed this supplement when treated with calcium carbonate. Five of 17 (29%) patients were withdrawn from calcium ketoglutarate therapy within 1 to 2 weeks due to intolerance (anorexia, vomiting, diarrhea, general uneasiness), whereas the remaining 12 patients did not experience any side effects at all. The five patients with calcium ketoglutarate intolerance all had pre-existing gastrointestinal symptoms; four of them had received treatment with cimetidine or omeprazol before inclusion into the study. Calculations based on median doses after 12 weeks showed that the cost of the therapy in Denmark was 10 times higher for calcium ketoglutarate compared with calcium carbonate (US$6.00/d v US$0.65/d). Calcium ketoglutarate may be an effective and safe alternative to treatment with aluminum-containing phosphate binders in patients on hemodialysis who are intolerant of calcium carbonate or acetate because of hypercalcemia. However, care must be exercised when dealing with patients with pre-existing gastrointestinal discomfort. Due to the high cost of the therapy, calcium ketoglutarate should be used only for selected patients.

Data on snow chemistry of the Cascade-Sierra Nevada Mountains

USGS Publications Warehouse

Laird, L.B.; Taylor, Howard E.; Lombard, R.E.

1986-01-01

Snow chemistry data were measured for solutes found in snow core samples collected from the Cascade-Sierra Nevada Mountains from late February to mid-March 1983. The data are part of a study to assess geographic variations in atmospheric deposition in Washington, Oregon, and California. The constituents and properties include pH and concentrations of hydrogen ion, calcium, magnesium, sodium, potassium, chloride, sulfate, nitrate, fluoride, phosphate, ammonium, iron, aluminum, manganese, copper, cadmium, lead, and dissolved organic carbon. Concentrations of arsenic and bromide were below the detection limit. (USGS)

Ultrastructural characters of a Physarum melleum on living leaves of Dendrobium candidum in China*

PubMed Central

Zhang, Jing-ze; Liu, Lu-ning; Fiore-Donno, Anna-Maria; Xu, Tong

2007-01-01

A known species, Physarum melleum, was found fruiting on living leaves of Dendrobium candidum, which was collected in China in 2004. Its morphological characters were revealed by light microscopy (LM), environmental scanning electron microscopy (ESEM) and scanning electron microscopy (SEM). Character variations were distinguished by its olive-yellow peridium and its always thinner capillitium containing globulose granular material between the large calcareous nodes. The calcium carbonate granules, deposited on stalks, peridium and hypothallus as well as within stalks, were globose and smooth. PMID:18257124

Geochemical models of metasomatism in ultramafic systems: Serpentinization, rodingitization, and sea floor carbonate chimney precipitation

USGS Publications Warehouse

Palandri, J.L.; Reed, M.H.

2004-01-01

In a series of water-rock reaction simulations, we assess the processes of serpentinization of harzburgite and related calcium metasomatism resulting in rodingite-type alteration, and seafloor carbonate chimney precipitation. At temperatures from 25 to 300??C (P = 10 to 100 bar), using either fresh water or seawater, serpentinization simulations produce an assemblage commonly observed in natural systems, dominated by serpentine, magnetite, and brucite. The reacted waters in the simulations show similar trends in composition with decreasing water-rock ratios, becoming hyper-alkaline and strongly reducing, with increased dissolved calcium. At 25??C and w/r less than ???32, conditions are sufficiently reducing to yield H2 gas, nickel-iron alloy and native copper. Hyperalkalinity results from OH- production by olivine and pyroxene dissolution in the absence of counterbalancing OH- consumption by alteration mineral precipitation except at very high pH; at moderate pH there are no stable calcium minerals and only a small amount of chlorite forms, limited by aluminum, thus allowing Mg2+ and Ca2+ to accumulate in the aqueous phase in exchange for H+. The reducing conditions result from oxidation of ferrous iron in olivine and pyroxene to ferric iron in magnetite. Trace metals are computed to be nearly insoluble below 300??C, except for mercury, for which high pH stabilizes aqueous and gaseous Hg??. In serpentinization by seawater at 300??C, Ag, Au, Pd, and Pt may approach ore-forming concentrations in sulfide complexes. Simulated mixing of the fluid derived from serpentinization with cold seawater produces a mineral assemblage dominated by calcite, similar to recently discovered submarine, ultramafic rock-hosted, carbonate mineral deposits precipitating at hydrothermal vents. Simulated reaction of gabbroic or basaltic rocks with the hyperalkaline calcium- and aluminum-rich fluid produced during serpentinization at 300??C yields rodingite-type mineral assemblages, including grossular, clinozoisite, vesuvianite, prehnite, chlorite, and diopside. ?? 2004 Elsevier Ltd.

Particle size of calcium carbonate does not affect apparent and standardized total tract digestibility of calcium, retention of calcium, or growth performance of growing pigs.

PubMed

Merriman, L A; Stein, H H

2016-09-01

Two experiments were conducted to evaluate particle size of calcium carbonate used in diets fed to growing pigs. Experiment 1 was conducted to determine apparent total tract digestibility (ATTD), standardized total tract digestibility (STTD), and retention of Ca among diets containing calcium carbonate produced to different particle sizes, and Exp. 2 was conducted to determine if growth performance of weanling pigs is affected by particle size of calcium carbonate. In Exp. 1, 4 diets based on corn and potato protein isolate were formulated to contain 0.70% Ca and 0.33% standardized total tract digestible P, but the calcium carbonate used in the diets was ground to 4 different particle sizes (200, 500, 700, or 1,125 μm). A Ca-free diet was formulated to determine basal endogenous losses of Ca. In Exp. 2, 4 diets were based on corn and soybean meal and the only difference among diets was that each diet contained calcium carbonate ground to the 4 particle sizes used in Exp. 1. In Exp. 1, 40 barrows (15.42 ± 0.70 kg initial BW) were allotted to the 5 diets with 8 replicate pigs per diet using a randomized complete block design, and in Exp. 2, 128 pigs with an initial BW of 9.61 ± 0.09 kg were randomly allotted to 4 experimental diets. Results of Exp. 1 indicated that basal endogenous losses of Ca were 0.329 g/kg DMI. The ATTD of Ca was 70.0 ± 3.2, 74.3 ± 2.7, 70.0 ± 2.9, and 72.1 ± 2.7 and the STTD of Ca was 74.2 ± 3.2, 78.5 ± 2.7, 74.1 ± 2.9, and 76.2 ± 2.7 for calcium carbonate ground to 200, 500, 700, or 1,125 μm, respectively. Retention of Ca was 67.4 ± 3.1, 70.4 ± 2.6, 63.9 ± 2.8, and 67.2 ± 2.2 for diets containing calcium carbonate ground to 200, 500, 700, or 1,125 μm, respectively. There were no differences among diets for ATTD of Ca, STTD of Ca, or retention of Ca. The ATTD of P was 64.5 ± 1.7, 66.8 ± 2.6, 64.2 ± 3.0, and 63.2 ± 1.7% and retention of P was 61.4 ± 1.4, 63.8 ± 2.8, 61.9 ± 2.8, and 60.9 ± 1.5 for diets containing calcium carbonate ground to 200, 500, 700, or 1,125 μm, respectively. Neither ATTD of P nor retention of P was influenced by the particle size of calcium carbonate. Results of Exp. 2 indicated that ADG, ADFI, and G:F were not impacted by the particle size of calcium carbonate. In conclusion, particle size of calcium carbonate did not affect ATTD of Ca, STTD of Ca, or retention of Ca; ATTD of P or retention of P; or growth performance of pigs. Any particle size of calcium carbonate in the range from 200 to 1,125 μm can therefore be used in diets fed to pigs.

Interactions between geomorphology and ecosystem processes in travertine streams: Implications for decommissioning a dam on Fossil Creek, Arizona

NASA Astrophysics Data System (ADS)

Marks, Jane C.; Parnell, Roderic; Carter, Cody; Dinger, Eric C.; Haden, G. Allen

2006-07-01

Travertine deposits of calcium carbonate can dominate channel geomorphology in streams where travertine deposition creates a distinct morphology characterized by travertine terraces, steep waterfalls, and large pools. Algae and microorganisms can facilitate travertine deposition, but how travertine affects material and energy flow in stream ecosystems is less well understood. Nearly a century of flow diversion for hydropower production has decimated the natural travertine formations in Fossil Creek, Arizona. The dam will be decommissioned in 2005. Returning carbonate-rich spring water to the natural stream channel should promote travertine deposition. How will the recovery of travertine affect the ecology of the creek? To address this question, we compared primary production, decomposition, and the abundance and diversity of invertebrates and fish in travertine and riffle/run reaches of Fossil Creek, Arizona. We found that travertine supports higher primary productivity, faster rates of leaf litter decomposition, and higher species richness of the native invertebrate assemblage. Observations from snorkeling in the stream indicate that fish density is also higher in the travertine reach. We postulate that restoring travertine to Fossil Creek will increase stream productivity, rates of litter processing, and energy flow up the food web. Higher aquatic productivity could fundamentally shift the nature of the stream from a sink to a source of energy for the surrounding terrestrial landscape.

Effect of calcium carbonate combined with calcitonin on hypercalcemia in hemodialysis patients.

PubMed

Wei, Yong; Kong, Xiang Lei; Li, Wen Bin; Wang, Zun Song

2014-12-01

This short-term study assessed the efficacy and safety of calcium carbonate combined with calcitonin in the treatment of hypercalcemia in hemodialysis patients. Patients (n=64) on hemodialysis for chronic kidney disease for more than 6 months were included based on total serum calcium more than 10.5 mg/dL. All patients were randomized (1:1) to receive calcium carbonate combined with calcitonin (Group I) or lanthanum carbonate (Group II) for 12 weeks. Blood levels of calcium, phosphorus and intact parathyroid hormone (iPTH) were measured every month, bone mass density (BMD) and coronary artery calcium scores (CACS) were measured at 3 months. During the study period, serum calcium decreased from 10.72 ± 0.39 to 10.09 ± 0.28 mg/dL (P < 0.05), serum phosphorus decreased from 6.79 ± 1.05 to 5.46 ± 1.18 mg/dL (P < 0.05), and serum iPTH levels in the Group I and Group II were not significantly different from the baseline. There were no significant differences in CACS in either group. There were no significant differences in the BMD values between Group I and baseline. In Group II, the BMD values at the lumbar spine and femoral neck were significantly lower than those before the trial and significantly lower than the corresponding values of Group I (P<0.05). Calcium carbonate combined with calcitonin and lanthanum carbonate were equally effective in the suppression of hypercalcemia in hemodialysis patients. There were no serious treatment-related adverse events in treatment with calcium carbonate combined with calcitonin. © 2014 The Authors. Therapeutic Apheresis and Dialysis © 2014 International Society for Apheresis.

Effects of nicergoline on calcium and magnesium deposition in the central nervous system tissues of rats maintained on low-calcium diets.

PubMed

Yasui, M; Kihira, T; Tsujimoto, M; Ota, K

1992-11-01

Reduction of calcium intake leads to the mobilization of calcium and magnesium from the bone pool and to calcium deposition in the soft tissues, especially in the central nervous system (CNS). The effects of 10 alpha-methoxy-1,6-dimethylergoline-8 beta-methanol 5-bromonicotinate (nicergoline), an ameliorator of cerebral circulation and metabolism, on the deposition of calcium and magnesium in the CNS, heart, liver, kidney, muscle, abdominal aorta and bones were studied in rats maintained on standard and low-calcium diets. Rats were fed the following diets for 90 days: standard calcium (12.5 g/kg); standard calcium with 60 mg/kg nicergoline; low-calcium (30 mg/kg); and low-calcium with 60 mg/kg nicergoline. The presence of nicergoline did not affect blood chemistry but magnesium concentrations in the liver were significantly (P < 0.05) higher in rats fed standard diet with nicergoline. Magnesium concentrations in the occipital cortex, pons, cerebellum, liver, kidney, muscle and femur of nicergoline-treated rats fed low-calcium diet were significantly (P < 0.01-0.05) higher compared with those in the corresponding controls, whereas the calcium concentrations in the femur of nicergoline-treated rats fed both standard and low-calcium diets were significantly (P < 0.05) higher than those in the corresponding controls. In general, nicergoline tended to preserve the calcium content in the bone of rats fed a standard diet. Nicergoline may be implicated in calcium metabolism in rats fed low-calcium diets and may activate cerebral metabolism through the maintenance of magnesium concentrations in the CNS and soft tissues.

Induction of calcite precipitation through heightened production of extracellular carbonic anhydrase by CO2 sequestering bacteria.

PubMed

Sundaram, Smita; Thakur, Indu Shekhar

2018-04-01

The thermo-alkalotolerant bacterium exhibiting heightened extracellular carbonic anhydrase (CA) activity, survived at 100 mM sodium bicarbonateand 5% gaseous CO 2 was identified as Bacillus sp. by 16S rRNA sequencing. Extracellular carbonic anhydrase was purified by ammonium sulfate precipitation, gel filtration chromatography and affinity chromatography with a yield of 46.61% and specific activity of 481.66 U/mg. The size of purified carbonic anhydrase was approximately 28 kDa in SDS-PAGE gel filtration and further their role in calcium carbonate production was correlated. The purified enzyme was stable with half-life of 25.36 min at 90 °C and pH 8. K M and Vmax values of the enzyme were 1.77 mg/mL and 385.69 U/mg respectively. The production of calcite was confirmed by Scanning Electron Microscopy (SEM) analysis, FTIR, and Energy-Dispersive X-ray (EDX) analysis. Carbonic anhydrase and calcite deposition coupled with CO 2 fixingbacteria is a significant approach for CO 2 sequestration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Efficacy and Safety of Sucroferric Oxyhydroxide and Calcium Carbonate in Hemodialysis Patients.

PubMed

Koiwa, Fumihiko; Yokoyama, Keitaro; Fukagawa, Masafumi; Akizawa, Tadao

2018-01-01

In this phase III, open-label, single-arm, multi-center 12-week study, we evaluated the efficacy and safety of combination therapy with sucroferric oxyhydroxide (PA21) and calcium carbonate for hemodialysis patients with hyperphosphatemia. We enrolled 35 subjects aged ≥ 20 years with end-stage kidney disease and serum phosphorus 3.5-6.0 mg/dl who were undergoing hemodialysis 3 times weekly and taking calcium carbonate and sevelamer hydrochloride. Patients switched from sevelamer hydrochloride and calcium carbonate to sucroferric oxyhydroxide and calcium carbonate. Sucroferric oxyhydroxide was orally administered 3 times daily within 750 mg/d (250 mg per dose) to 3000 mg/d (1000 mg per dose), immediately before every meal, for 12 weeks. Calcium carbonate was orally administered 3 times daily after every meal. Outcomes were serum phosphorus concentration, safety, and satisfaction with bowel movements. Mean (SD) serum phosphorus concentrations were 5.01 (0.63) mg/dl at week 0 and 4.89 (1.14) mg/dl at the end of treatment, after patients switched from sevelamer hydrochloride to sucroferric oxyhydroxide. The incidence of adverse drug reactions was 31.4% (11/35), with diarrhea being the most frequent (31.4%). More sucroferric oxyhydroxide-treated patients were satisfied with their bowel movements. More patients with constipation, as well as those who experienced diarrhea, were satisfied with their bowel movements at the end of the study. Combined administration of sucroferric oxyhydroxide and calcium carbonate at low doses was effective in maintaining serum phosphorus concentrations within the target range, and patients' gastrointestinal status improved. Sucroferric oxyhydroxide maintained its serum phosphorus-lowering effect with a decreased pill burden, and its concomitant administration with calcium carbonate was well tolerated.

76 FR 47147 - Pure Magnesium in Granular Form From the People's Republic of China: Rescission of Antidumping...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-04

.... SUPPLEMENTARY INFORMATION: Background On November 1, 2010, the Department published a notice of opportunity to... granular materials of which the Department is aware used to make such excluded reagents are: lime, calcium metal, calcium silicon, calcium carbide, calcium carbonate, carbon, slag coagulants, fluorspar...

Fractional absorption of active absorbable algal calcium (AAACa) and calcium carbonate measured by a dual stable-isotope method

USDA-ARS?s Scientific Manuscript database

With the use of stable isotopes, this study aimed to compare the bioavailability of active absorbable algal calcium (AAACa), obtained from oyster shell powder heated to a high temperature, with an additional heated seaweed component (Heated Algal Ingredient, HAI), with that of calcium carbonate. In ...

FT-Raman spectroscopic study of calcium-rich and magnesium-rich carbonate minerals.

PubMed

Edwards, Howell G M; Villar, Susana E Jorge; Jehlicka, Jan; Munshi, Tasnim

2005-08-01

Calcium and magnesium carbonates are important minerals found in sedimentary environments. Although sandstones are the most common rock colonized by endolith organisms, the production of calcium and magnesium carbonates is important in survival strategies of organisms and as a source for the removal of oxalate ions. Extremophile organisms in some situations may convert or destroy carbonates of calcium and magnesium, which gives important information about the conditions under which these organisms can survive. The identification on the surface of Mars of 'White Rock' formations, in Juventae Chasma or Sabaea Terra, as possibly carbonate rocks makes the study of these minerals a prerequisite of remote Martian exploration. Here, we show the protocol for the identification by Raman spectroscopy of different calcium and magnesium carbonates and we present a database of relevance in the search for life, extinct or extant, on Mars; this will be useful for the assessment of data obtained from remote, miniaturized Raman spectrometers now proposed for Mars exploration.

Isotopic evidence for variations in the marine calcium cycle over the Cenozoic.

PubMed

De La Rocha, C L; DePaolo, D J

2000-08-18

Significant variations in the isotopic composition of marine calcium have occurred over the last 80 million years. These variations reflect deviations in the balance between inputs of calcium to the ocean from weathering and outputs due to carbonate sedimentation, processes that are important in controlling the concentration of carbon dioxide in the atmosphere and, hence, global climate. The calcium isotopic ratio of paleo-seawater is an indicator of past changes in atmospheric carbon dioxide when coupled with determinations of paleo-pH.

Phytoplankton calcification as an effective mechanism to alleviate cellular calcium poisoning

NASA Astrophysics Data System (ADS)

Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

2015-11-01

Marine phytoplankton have developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological timescales. For example, the Cretaceous (145 to 66 Ma), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to 4 times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to alleviate cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations. The exact function of calcification and the reason behind the highly ornate physical structures of coccoliths remain elusive.

Paleosol Proxies for Low Elevation Paleoclimate East of the Andes, Northwestern Argentina

NASA Astrophysics Data System (ADS)

Rosario, J. J.; Jordan, T. E.; Garzione, C. N.; Higgins, P.; Hernandez, R.; Hernandez, J.

2009-12-01

Paleosols can be used as a proxy for paleoclimate, paleoenvironment, and geomorphological reconstructions. The weathering imprint in the minerals in paleosols can be used as a proxy for moisture conditions, while other environmental information can be obtained from stable isotopes in their minerals such as δ13C and δ18O. The goal of this study is to document changes in paleosol characteristics’ driven by climate change in NW Argentina over the time period between ~14 Ma and 5.1 Ma during a time of significant uplift and climate change in the Altiplano. During this time interval, landscape of the low elevation foreland basin changed as the consequence of the propagation of Andean thrust-fold deformation. Paleosols are interbedded in three stratigraphic sections that are described, sampled, and studied along the Iruya, Peña Colorada, and La Porcelana rivers, distributed from west to east, respectively. Field observations of the paleosols, stratigraphic column construction, thin section petrography and textures, x-ray diffraction (XRD), and stable isotopes together provide climatic proxies. These The stratigraphic columns represent a distributary depositional system, or megafan, whose syn-deformational nature is documented by Echevarría et al. (2003). Argillic-calcic paleosols developed on silty and sandy mudstones in the floodplain environment, with pedogenic calcium carbonate formed as nodules and rizoliths. The Microscopic features show that paleosols on the floodplain contain argillans. Semi-humid to semi-arid conditions are suggested by clay lessivage and calcium carbonate precipitation respectively. The mineralogy reflected by the XRD shows kaolinite, illite, and calcium carbonate in the western stratigraphic column that represents moderate climatic conditions (semi-humid to semi-arid). The coexistence of these minerals suggests seasonal variations in moisture. The eastern columns exhibit wetter soil conditions, including oxide minerals as well as hematite and goethite. Carbon isotopes show C3 vegetation with an increase in δ13C values most likely resulting from increasing seasonality in more recent times. There is little variation in δ18O values through time. In conclusion, these proxies show that soils were developed on interchannel areas, with illuviation of clays during the wet season and precipitation of calcium carbonate during the dry season. Although the megafan migrated eastward and the Altiplano rose, oxygen isotopes suggest that neither rainfall amount nor source of water vapor changed through the approximately 10 million years time interval.

Calcium acetate or calcium carbonate for hyperphosphatemia of hemodialysis patients: a meta-analysis.

PubMed

Wang, Yong; Xie, Guoqiang; Huang, Yuanhang; Zhang, Han; Yang, Bo; Mao, Zhiguo

2015-01-01

High levels of serum phosphorus both at baseline and during follow-up are associated with increased mortality in dialysis patients, and administration of phosphate binders was independently associated with improved survival among hemodialysis population. Calcium-based phosphate binders are the most commonly used phosphate binders in developing countries for their relatively low costs. To compare the efficacy and safety between calcium carbonate and calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients. PubMed, EMBASE, Cochrane Library, Google scholar and Chinese databases (Wanfang, Weipu, National Knowledge Infrastructure of China) were searched for relevant studies published before March 2014. Reference lists of nephrology textbooks and review articles were checked. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of calcium acetate and calcium carbonate in adult patients with MHD was performed using Review Manager 5.0. A total of ten studies (625 participants) were included in this meta-analysis. There was insufficient data in all-cause mortality and cardiovascular events for meta-analysis. Compared with calcium carbonate group, the serum phosphorus was significantly lower in calcium acetate group after4 weeks' administration (MD -0.15 mmol/L, 95% CI -0.28 to -0.01) and after 8 weeks' administration (MD -0.25 mmol/L, 95% CI -0.40 to -0.11). There was no difference in serum calcium levels or the incidence of hypercalcemia between two groups at 4 weeks and 8 weeks. No statistical difference was found in parathyroid hormone (PTH) levels or serum calcium by phosphorus (Ca x P) product. There was significantly higher risk of intolerance with calcium acetate treatment (RR 3.46, 95% CI 1.48 to 8.26). For hyperphosphatemia treatment, calcium acetate showed better efficacy and with a higher incidence of intolerance compared with calcium carbonate. There are insufficient data to establish the comparative superiority of the two calcium-based phosphate binders on all-cause mortality and cardiovascular end-points in hemodialysis patients.

Composite mathematical modeling of calcium signaling behind neuronal cell death in Alzheimer's disease.

PubMed

Ranjan, Bobby; Chong, Ket Hing; Zheng, Jie

2018-04-11

Alzheimer's disease (AD) is a progressive neurological disorder, recognized as the most common cause of dementia affecting people aged 65 and above. AD is characterized by an increase in amyloid metabolism, and by the misfolding and deposition of β-amyloid oligomers in and around neurons in the brain. These processes remodel the calcium signaling mechanism in neurons, leading to cell death via apoptosis. Despite accumulating knowledge about the biological processes underlying AD, mathematical models to date are restricted to depicting only a small portion of the pathology. Here, we integrated multiple mathematical models to analyze and understand the relationship among amyloid depositions, calcium signaling and mitochondrial permeability transition pore (PTP) related cell apoptosis in AD. The model was used to simulate calcium dynamics in the absence and presence of AD. In the absence of AD, i.e. without β-amyloid deposition, mitochondrial and cytosolic calcium level remains in the low resting concentration. However, our in silico simulation of the presence of AD with the β-amyloid deposition, shows an increase in the entry of calcium ions into the cell and dysregulation of Ca 2+ channel receptors on the Endoplasmic Reticulum. This composite model enabled us to make simulation that is not possible to measure experimentally. Our mathematical model depicting the mechanisms affecting calcium signaling in neurons can help understand AD at the systems level and has potential for diagnostic and therapeutic applications.

Bioprecipitation of Calcium Carbonate Crystals by Bacteria Isolated from Saline Environments Grown in Culture Media Amended with Seawater and Real Brine

PubMed Central

Silva-Castro, G. A.; Uad, I.; Gonzalez-Martinez, A.; Rivadeneyra, A.; Gonzalez-Lopez, J.; Rivadeneyra, M. A.

2015-01-01

The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater and real brine obtained in a desalination plant growth in culture media containing seawater and brine as mineral sources has been studied. However, only bioprecipitation was detected when the bacteria were grown in media with added organic matter. Biomineralization process started rapidly, crystal formation taking place in the beginning a few days after inoculation of media; roughly 90% of total cultivated bacteria showed. Six major colonies with carbonate precipitation capacity dominated bacterial community structure cultivated in heterotrophic platable bacteria medium. Taxonomic identification of these six strains through partial 16S rRNA gene sequences showed their affiliation with Gram-positive Bacillus and Virgibacillus genera. These strains were able to form calcium carbonate minerals, which precipitated as calcite and aragonite crystals and showed bacterial fingerprints or bacteria calcification. Also, carbonic anhydrase activity was observed in three of these isolated bacteria. The results of this research suggest that microbiota isolated from sea water and brine is capable of precipitation of carbonate biominerals, which can occur in situ with mediation of organic matter concentrations. Moreover, calcium carbonate precipitation ability of this microbiota could be of importance in bioremediation of CO2 and calcium in certain environments. PMID:26273646

Bioprecipitation of Calcium Carbonate Crystals by Bacteria Isolated from Saline Environments Grown in Culture Media Amended with Seawater and Real Brine.

PubMed

Silva-Castro, G A; Uad, I; Gonzalez-Martinez, A; Rivadeneyra, A; Gonzalez-Lopez, J; Rivadeneyra, M A

2015-01-01

The precipitation of calcium carbonate and calcium sulphate by isolated bacteria from seawater and real brine obtained in a desalination plant growth in culture media containing seawater and brine as mineral sources has been studied. However, only bioprecipitation was detected when the bacteria were grown in media with added organic matter. Biomineralization process started rapidly, crystal formation taking place in the beginning a few days after inoculation of media; roughly 90% of total cultivated bacteria showed. Six major colonies with carbonate precipitation capacity dominated bacterial community structure cultivated in heterotrophic platable bacteria medium. Taxonomic identification of these six strains through partial 16S rRNA gene sequences showed their affiliation with Gram-positive Bacillus and Virgibacillus genera. These strains were able to form calcium carbonate minerals, which precipitated as calcite and aragonite crystals and showed bacterial fingerprints or bacteria calcification. Also, carbonic anhydrase activity was observed in three of these isolated bacteria. The results of this research suggest that microbiota isolated from sea water and brine is capable of precipitation of carbonate biominerals, which can occur in situ with mediation of organic matter concentrations. Moreover, calcium carbonate precipitation ability of this microbiota could be of importance in bioremediation of CO2 and calcium in certain environments.

Influence of Calcium Carbonate on Cobalt Phytoavailability in Fluvo-aquic Soil

NASA Astrophysics Data System (ADS)

Wang, Mengyuan; Liu, Borui; Ma, Yufei; Xue, Qianhui; Huang, Qing

2017-12-01

In order to study the efficacy of calcium carbonate for cobalt (Co) fixation, as well as its influence on chemical speciation of Co in fluvo-aquic soil, pakchoies were planted in the soil with different quantities of exogenous Co and calcium carbonate. Co concentrations in the mature plant shoots were analyzed, and the chemical speciation of Co were detected with the Tessier five-step sequential extraction. The results showed that the Co concentration in plants tended to decrease first and then get higher with the concentration of calcium carbonate increasing (0-12g/kg) in soil (P < 0.05). The proportion of Co in the exchangeable form in the soil followed the similar tendency (P < 0.05), which might transform from the exchangeable form into the carbonate-associated and organic-associated forms. A regression analysis showed that when the concentrations of calcium carbonate were in the range of 5.0 to 7.5 g/kg, Co concentration in the plant reached to the lowest point, while the proportion of Co in the exchangeable form reached the minimum. In conclusion, to get the optimum effect, the dosage of calcium carbonate should be kept in the range of 5.0 to 7.5 g/kg when it is applied to Co fixation.

New agent to treat elevated phosphate levels: magnesium carbonate/calcium carbonate tablets.

PubMed

Meyer, Caitlin; Cameron, Karen; Battistella, Marisa

2012-01-01

In summary, Binaphos CM, a magnesium carbonate/calcium carbonate combination phosphate binder, is marketed for treating elevated phosphate levels in dialysis patients. Although studies using magnesium/calcium carbonate as a phosphate binder are short term with small numbers of patients, this phosphate binder has shown some promising results and may provide clinicians with an alternative for phosphate binding. Using a combination phosphate binder may reduce pill burden and encourage patient compliance. In addition to calcium and phosphate, it is imperative to diligently monitor magnesium levels in patients started on this medication, as magnesium levels may increase with longer duration of use. Additional randomized controlled trials are necessary to evaluate long-term efficacy and safety of this combination phosphate binder.

Improving the desulfurization performance of CaCO3 with sodium humate

NASA Astrophysics Data System (ADS)

Feng, Run; Sun, Zhiguo; Zhang, Wenqing; Huang, Hao; Hu, Haihang; Zhang, Li; Xie, Hongyong

2018-02-01

The influence of these factors on desulphurization efficiency was studied by changing the amount of calcium carbonate, the concentration of sulfur dioxide, the liquid flow rate of absorbent and the air flow rate, the optimum working condition was determined by the research of limestone-gypsum desulphurization process commonly used in industry. By changing the amount of calcium carbonate, we conclude that the volume of water in the desulfurization efficiency does not increase with the adding amount of calcium carbonate. The optimum conditions were determined : at the condicion of the concentration of 500ppm of sulfur dioxide, 10g calcium carbonate, 150L/h liquid flow and the minimum air flow rate of 6.75m3/h, the highest desulfurization efficiency was close to 100% when sodium humate was not added, but the holding time was only about 5 minutes. After adding 3g of humic acid, the desulfurization efficiency was improved obviously, and the instantaneous efficiency of 100% lasting for about 40 minutes. It can be seen that, calcium carbonate in the addition of humic acid sodium can significantly improve the absorption of calcium carbonate performance of SO2.

In-Situ Production of Calcium Carbonate Nanoparticles in Fresh Concrete Using Pre-carbonation Method

NASA Astrophysics Data System (ADS)

Qian, Xin

To reduce the carbon footprint of ordinary Portland cement (OPC)-based concrete, a novel technique, pre-carbonation process, has been developed to produce CaCO3 nanoparticles in fresh concrete. In this technique, gaseous CO2 is first absorbed into a slurry of calcium-rich minerals which is then blended with other ingredients to produce mortar/concrete. The objective of this work is to obtain an in-depth understanding of the underlying scientific mechanisms associated with the enhancement of strength and durability of the concrete induced by the new method. A comprehensive research plan has been carried out to study the carbonated slaked lime slurry and the effect of carbonated slaked lime slurry on the performance of OPC-based concrete, and to evaluate the potentials of the pre-carbonation method. Experimental studies show that carbonating the calcium-rich mineral slurry with CO2 can produce CaCO3 nanoparticles and Ca(HCO 3)2 in the slurry, and these carbonation products were dictated by four parameters of the pre-carbonation method: the duration and temperature of the carbonation, the concentration of the calcium source slurry, and the stirring method of the calcium source slurry during the carbonation. The mechanical properties and durability of the mortar/concrete made with the carbonated slurry were significantly improved, which can be attributed to major mechanisms induced by the pre-carbonation method: promoted hydration of the cement and denser microstructure of the mortar/concrete. Calorimetry testing showed that the hydration of OPC was greatly improved by the pre-carbonation because of the extra heterogenous nucleation sites provided by the CaCO3 nanoparticles. XRD and TGA results revealed that more ettringite was produced in the mortar/concrete with pre-carbonated slaked lime slurry. The overall volume of the hydration products of the cement was increased by the pre-carbonation, leading to denser microstructure of the mortar/concrete. It has been found that the pre-carbonation can be used to the OPC-supplementary cementitious materials (SCMs) blended cement mortar/concrete, as evidenced by the improved mechanical properties achieved by these mortars produced by using the pre-carbonation method. A preliminary study was also conducted to examine whether other calcium-rich minerals, such as Class C fly ash and limestone, can be used as calcium source in the pre-carbonation method.

[Effects of fertilizing regime and planting age on soil calcium decline in Luochuan apple orchards].

PubMed

Li, Peng; Li, Chun Yue; Wang, Yi Quan; Jiao, Cai Qiang

2017-05-18

This study was conducted to assess the effects of fertilizing regime and orchard planting age on soil calcium contents and stocks in the apple orchards on the Loess Plateau. The apple orchards in Luochuan County, one of the best regions for apple plantation in the world, were selec-ted in this study. The contents of calcium carbonate,water-soluble calcium and exchangeable cal-cium at 0-100 cm soil layer under different fertilizing regimes and various planting ages were mea-sured, their stocks were calculated and their variation features were analyzed. The results showed that soil in the apple orchards in the study region was characterized by the decline in calcium contents. The decline was more serious in apple orchards with long-term application of chemical fertili-zer than in those with combined application of chemical fertilizer and farmyard manure. The average contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in apple orchards with long-term application of chemical fertilizer decreased by 38.8%, 25.4% and 5.6% respectively than those in the apple orchards with long-term application of both chemical fertilizer and farmyard manure. The stocks of calcium carbonate, water-soluble calcium and exchangeable calcium decreased by 36.4%, 26.0% and 4.3%, respectively. The decline of soil cal-cium was aggravated with the increase of orchard planting age. The contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in orchards of more than 25 years of planting age decreased by 48.8%, 69.4% and 39.5% respectively, compared with orchards of less than 10 years of planting age, and the stocks decreased by 40.8%, 64.1% and 33.0%, respectively. These results indicated that either long-term application of chemical fertilizer or long-term plantation of apple trees obviously depleted soil calcium carbonate, water-soluble calcium and exchangeable calcium. Therefore, it was recommended that application of chemical fertilizer and farmyard manure should be combined to mitigate soil calcium decline, and calcium management should be strengthened in apple orchards of more than 25 years of planting age. The fertilizing regime was a driving factor of soil calcium decline which had a significant temporal (orchard planting age) and spatial (soil depth) effect.

Analytical electron microscopy of biogenic and inorganic carbonates

NASA Technical Reports Server (NTRS)

Blake, David F.

1989-01-01

In the terrestrial sedimentary environment, the mineralogically predominant carbonates are calcite-type minerals (rhombohedral carbonates) and aragonite-type minerals (orthorhombic carbonates). Most common minerals precipitating either inorganically or biogenically are high magnesium calcite and aragonite. High magnesium calcite (with magnesium carbonate substituting for more than 7 mole percent of the calcium carbonate) is stable only at temperatures greater than 700 C or thereabouts, and aragonite is stable only at pressures exceeding several kilobars of confining pressure. Therefore, these carbonates are expected to undergo chemical stabilization in the diagenetic environment to ultimately form stable calcite and dolomite. Because of the strong organic control of carbonate deposition in organisms during biomineralization, the microchemistry and microstructure of invertebrate skeletal material is much different than that present in inorganic carbonate cements. The style of preservation of microstructural features in skeletal material is therefore often quite distinctive when compared to that of inorganic carbonate even though wholesale recrystallization of the sediment has taken place. Microstructural and microchemical comparisons are made between high magnesium calcite echinoderm skeletal material and modern inorganic high magnesium calcite inorganic cements, using analytical electron microscopy and related techniques. Similar comparisons are made between analogous materials which have undergone stabilization in the diagenetic environment. Similar analysis schemes may prove useful in distinguishing between biogenic and inorganic carbonates in returned Martian carbonate samples.

Deposits in artificial corneas: risk factors and prevention.

PubMed

Hicks, Celia R; Chirila, Traian V; Werner, Liliana; Crawford, Geoffrey J; Apple, David J; Constable, Ian J

2004-04-01

To identify risk factors for calcium deposition and pigmented staining within AlphaCor artificial corneas. Retrospective analysis of data from 72 AlphaCor implantations was conducted. Histological analysis of explants was performed. Eight cases of either intraoptic calcium or pigment deposition occurred in AlphaCor patients between 2.5 and 21 months after implantation. Four cases had diffuse white deposits, confirmed to be calcium and associated with prior coadministration of topical steroids and beta-blockers. The other four cases had brown deposits, associated with cigarette smoking and topical levobunolol. These findings led to changes in patient management protocols, surgeon training and patient information so as to minimize the risk of further occurrences. No further cases of white deposition have occurred after warning surgeons of the risk associated with certain topical therapy combinations. The risk of brown staining may be difficult to remove completely as it appears that environmental exposure to chemicals may cause deposition in addition to personal smoking habits and topical medications.

Calcium carbonate crystals promote calcium oxalate crystallization by heterogeneous or epitaxial nucleation: possible involvement in the control of urinary lithogenesis.

PubMed

Geider, S; Dussol, B; Nitsche, S; Veesler, S; Berthézène, P; Dupuy, P; Astier, J P; Boistelle, R; Berland, Y; Dagorn, J C; Verdier, J M

1996-07-01

A large proportion of urinary stones have calcium oxalate (CaOx) as the major mineral phase. In these stones, CaOx is generally associated with minor amounts of other calcium salts. Several reports showing the presence of calcium carbonate (CaCO3) and calcium phosphate in renal stones suggested that crystals of those salts might be present in the early steps of stone formation. Such crystals might therefore promote CaOx crystallization from supersaturated urine by providing an appropriate substrate for heterogeneous nucleation. That possibility was investigated by seeding a metastable solution of 45Ca oxalate with vaterite or calcite crystallites. Accretion of CaOx was monitored by 45Ca incorporation. We showed that (1) seeds of vaterite (the hexagonal polymorph of CaCO3) and calcite (the rhomboedric form) could initiate calcium oxalate crystal growth; (2) in the presence of lithostathine, an inhibitor of CaCO3 crystal growth, such accretion was not observed. In addition, scanning electron microscopy demonstrated that growth occurred by epitaxy onto calcite seeds whereas no special orientation was observed onto vaterite. It was concluded that calcium carbonate crystals promote crystallization of calcium oxalate and that inhibitors controlling calcium carbonate crystal formation in Henle's loop might play an important role in the prevention of calcium oxalate stone formation.

Exaggerated levothyroxine malabsorption due to calcium carbonate supplementation in gastrointestinal disorders.

PubMed

Csako, G; McGriff, N J; Rotman-Pikielny, P; Sarlis, N J; Pucino, F

2001-12-01

To describe a patient with primary hypothyroidism in whom ingestion of levothyroxine with calcium carbonate led to markedly elevated serum thyrotropin concentrations. A 61-year-old white woman with primary hypothyroidism, systemic lupus erythematosus, celiac disease, and history of Whipple resection for pancreatic cancer was euthyroid with levothyroxine 175-188 micrograms/d. After taking a high dose of calcium carbonate (1250 mg three times daily) with levothyroxine, she developed biochemical evidence of hypothyroidism (thyrotropin up to 41.4 mU/L) while remaining clinically euthyroid. Delaying calcium carbonate administration by four hours returned her serum thyrotropin to a borderline high concentration (5.7 mU/L) within a month. Serum concentrations of unbound and total thyroxine and triiodothyronine tended to decrease, but remained borderline low to normal while the patient concomitantly received levothyroxine and calcium carbonate. Concomitant administration of levothyroxine and calcium carbonate often results in levothyroxine malabsorption. While in most patients the clinical consequences of this interaction, even with prolonged exposure, are relatively small, overt hypothyrodism may develop in patients with preexisting malabsorption disorders. However, as the current case illustrates, the clinical manifestations of the initial levothyroxine deficit may not always be apparent and, of all usual laboratory thyroid function tests, only thyrotropin measurement will reliably uncover the exaggerated levothyroxine malabsorption. Decreased absorption of levothyroxine when given with calcium carbonate may be particularly pronounced in patients with preexisting malabsorption disorders. Once recognized, a change in drug administration schedule usually minimizes or eliminates this interaction.

Live celloidosome structures based on the assembly of individual cells by colloid interactions.

PubMed

Fakhrullin, Rawil F; Brandy, Marie-Laure; Cayre, Olivier J; Velev, Orlin D; Paunov, Vesselin N

2010-10-14

A new class of colloid structures, celloidosomes, has been developed which represent hollow microcapsules whose membranes consist of a single monolayer of living cells. Two routes for producing these structures were designed based on templating of: (i) air bubbles and (ii) anisotropic microcrystals of calcium carbonate with living cells, which allowed us to fabricate celloidosomes of spherical, rhombohedral and needle-like morphologies. Air microbubbles were templated by yeast cells coated with poly(allylamine hydrochloride) (PAH), then coated with carboxymethylcellulose and rehydrated resulting in the formation of spherical multicellular structures. Similarly, calcium carbonate microcrystals of anisotropic shapes were coated with several consecutive layers of oppositely charged polyelectrolytes to obtain a positive surface charge which was used to immobilise yeast cells coated with anionic polyelectrolyte of their surfaces. After dissolving of sacrificial cores, hollow multicellular structures were obtained. The viability of the cells in the produced structures was confirmed by using fluorescein diacetate. In order to optimize the separation of celloidosomes from free cells magnetic nanoparticles were immobilised onto the surface of templates prior to the cells deposition, which greatly facilitated the separation using a permanent magnet. Two alternative approaches were developed to form celloidosome structures using magnetically functionalised core-shell microparticles which resulted in the formation of celloidosomes with needle-like and cubic-like geometries which follows the original morphology of the calcium carbonate microcrystals. Our methods for fabrication of celloidosomes may found applications in the development of novel symbiotic bio-structures, artificial multicellular organisms and in tissue engineering. The unusual structure of celloidosomes resembles the primitive forms of multicellular species, like Volvox, and other algae and could be regarded as one possible mechanism of the evolutionary development of multicellularity.

A comparative study of calcium absorption following a single serving administration of calcium carbonate powder versus calcium citrate tablets in healthy premenopausal women

PubMed Central

Wang, Haiyuan; Bua, Peter; Capodice, Jillian

2014-01-01

Background Calcium is an essential mineral often taken as a daily, long-term nutritional supplement. Data suggests that once-daily dosing is important with regard to long-term compliance of both drugs and nutritional supplements. Objective This study was undertaken to compare the bioavailability of a single serving of two calcium supplements in healthy, premenopausal women. Design A two-period, crossover bioavailability study of a single serving of calcium citrate tablets (two tablets=500 mg calcium) versus a single serving of calcium carbonate powder (one packet of powder=1,000 mg calcium) was performed in healthy women aged between 25 and 45. All subjects were on a calcium-restricted diet 7 days prior to testing and fasted for 12 h before being evaluated at 0, 1, 2, and 4 h after oral administration of the test agents. Blood measurements for total and ionized calcium and parathyroid hormone were performed and adverse events were monitored. Results Twenty-three women were evaluable with a mean age of 33.2±8.71. Results showed that administration of a single serving of a calcium carbonate powder resulted in greater absorption in total and ionized calcium versus a single serving of calcium citrate tablets at 4 h (4.25±0.21 vs. 4.16±0.16, p=0.001). There were minimal side effects and no reported serious adverse events. Conclusions This study shows that a single serving of a calcium carbonate powder is more bioavailable than a single serving of calcium citrate tablets. This may be beneficial for long-term compliance. PMID:24772062

[Calcium carbonate for the treatment of hyperphosphatemia in chronic hemodialysis patients].

PubMed

Kiss, D; Battegay, M; Meier, C; Lyrer, A

1990-03-03

Hyperphosphatemia in chronic hemodialysis patients is usually treated with aluminium containing phosphate binders. In recent years there has been increasing evidence of serious complications due to aluminium accumulation. We have investigated a new calcium carbonate preparation with an HCl-resistant capsule designed to prevent gastrointestinal side effects. Its phosphate binding capacity in comparison to aluminium chloride hydroxide was investigated in 17 chronic hemodialysis patients. The dose of the phosphate binder was adjusted regularly so that the serum phosphorus levels were below 1.8 mmol/l. The mean dose of aluminium chloride hydroxide was 3.36 g/day and of calcium carbonate 4.96 g/day. The mean (+/- SD) serum calcium level was 2.58 +/- 0.11 mmol/l under aluminium chloride hydroxide and 2.50 +/- 0.25 mmol/l under calcium carbonate. The mean phosphorus level was 1.69 +/- 0.31 mmol/l under aluminium chloride hydroxide and 1.71 +/- 0.33 under calcium carbonate. Serum aluminium fell from 64.5 +/- 14.4 micrograms/l to 28.5 +/- 17.5 micrograms/l after 3 months.

The geochemical record of the last 17,000 years in the Guaymas Basin, Gulf of California

USGS Publications Warehouse

Dean, W.E.

2006-01-01

Sediments deposited on the western slope of the Guaymas Basin in the central Gulf of California are composed predominantly of detrital clastic material and biogenic silica (biopal), with minor organic material (average of 2.8% organic carbon) and calcium carbonate. The CaCO3 is derived from calcareous plankton and is highly variable ranging from 0% to 16%. In general, the CaCO3 content of the sediments varies inversely with the biopal content, reflecting the relative abundance of calcareous and siliceous plankton in the photic zone. Siliceous plankton dominate when winds are predominantly out of the northwest producing strong upwelling. Calcareous plankton indicates weak southeasterly winds that bring warm, tropical Pacific surface water into the Gulf. Based mainly on relative abundances of biopal and CaCO3, the sediments deposited over the last 17,000 years in the western Guaymas Basin can be divided into five intervals. In general, the sediments in the intervals with high biopal and low CaCO3 are laminated, but this is not always true. Unlike most other continental margins of the world with well-developed oxygen minimum zones where highest concentrations of organic carbon and redox-sensitive trace metals occur in laminated sediments, the laminated sediments on the anoxic slope of the western Guaymas Basin do not always have the highest concentrations of organic carbon and trace metals such as Mo and Cd.

[Gallbladder Stone Types in Patients with Cholelithiasis and Clonorchis sinensis Infection in the Endemic Area of Clonorchiasis].

PubMed

Ma, Rui-hong; Qiao, Tie; Luo, Zhen-liang; Luo, Xiao-bing; Zheng, Pei-ming; Yang, Liu-qing

2015-06-01

To investigate the relationship between Clonorchis sinensis infection and the gallbladder stone type in patients with cholelithiasis in the endemic area of clonorchiasis. Gallbladder stones were collected from 598 patients with cholelithiasis through minimally invasive gallbladder-preserving cholelithotomy in the Sixth People's Hospital of Nansha District from May 2009 to October 2012. The stone samples were analyzed for composition by Fourier transform infrared spectroscopy to identify their types. The Clonorchis sinensis eggs were detected in the stones by microscopic examination, and the detection rates of eggs were calculated for different stone types. Then the clinical characteristics and biochemical indicators were compared among patients with different types of stones, as well as between Clonorchis sinensis egg-positive and -negative patients with the calcium-carbonate type of stones. Some calcium-carbonate stones positive for Clonorchis sinensis eggs were randomly selected for further scanning electron microscopy (SEM) examination. Of the stones from 598 patients, 234 (39.1%) were cholesterol type, 133 (22.2%) bile pigment type, 112(18.7%) calcium-carbonate type, 86 (14.4%) mixed types and 33(5.5%) were others. The detection rate of Clonorchis sinensis eggs in these types was 6% (15/234), 44% (59/133), 60% (67/112), 36% (31/ 86) and 30% (10/33), respectively, being highest in calcium-carbonate stones while lowest in cholesterol stones. The Co2-combining power of the plasma was higher in patients with calcium-carbonate and mixed stones than in those with cholesterol stones (P < 0.05), and the CO2-combining power of the bile and biliary pH were both higher in patients with calcium-carbonate types than in those with other types (P < 0.05). In addition, in patients with calcium-carbonate stones, the CO2-combining powers of the plasma and the bile, as well as biliary pH were all higher in the egg-positives than in the egg-negatives. Further, both light microscopy and SEM revealed adherence of the Clonorchis sinensis eggs to calcium-carbonate crystals. The infection rate of Clonorchis sinensis is higher in patients with calcium-carbonate gallbladder stones than in those with other types of stones.

Integrated stratigraphy of a shallow marine Paleocene-Eocene boundary section, MCBR cores, Maryland (USA)

NASA Astrophysics Data System (ADS)

Self-Trail, J. M.; Robinson, M. M.; Edwards, L. E.; Powars, D. S.; Wandless, G. A.; Willard, D. A.

2013-12-01

An exceptional Paleocene-Eocene boundary section occurs in a cluster of six short (<15m) coreholes (MCBR 1 through 6) drilled near Mattawoman Creek in western Charles County, Maryland. The sediments consist of glauconite-rich sand of the upper Paleocene Aquia Formation and silty clay of the lower Eocene Marlboro Clay. Sediment samples were analyzed for carbon and oxygen isotopes, percent calcium carbonate, calcareous nannofossils, planktic and benthic foraminifera, dinoflagellates, pollen, and lithology. A well-defined carbon isotope excursion (CIE) documents a gradual negative shift in δ13C values that starts below the lithologic break between the Aquia Formation and the Marlboro Clay. A benthic foraminifer extinction event, reduction of calcareous nannofossil assemblages, and change in core color from gray to alternating gray and pink also occurs within the CIE transition. These alternating changes in color coincide with cyclic peaks in the carbon isotope and percent calcium carbonate curves, where gray color corresponds to a positive shift in carbon isotope values and to a corresponding increase in percent benthic and planktic foraminifera. The upper third of the Marlboro Clay is barren of all calcareous microfossil material, although the presence of foraminiferal molds and linings proves that deposition occurred in a marine environment. Co-occurrence of the dinoflagellates Apectodinium augustum and Phthanoperidinium crenulatum at the top of the Marlboro Clay suggests that the Marlboro Clay at Mattawoman Creek is truncated. This is corroborated by the absence in the Marlboro of specimens of the calcareous nannofossil Rhomboaster-Discoaster assemblage, which is restricted to early Eocene Zone NP9b. Based on planktic/benthic foraminifera ratios, deposition of sediments at Mattawoman Creek occurred predominantly in an inner neritic environment, at water depths between 25-50 m. Occasional deepening to approximately 75m (middle neritic environment) occurred in the early Eocene, as represented by the basal Marlboro Clay. The planktic/benthic ratio, however, could also be affected by surface productivity and/or river runoff. The gradual shift up-section in core color from gray to alternating gray and red, to dark red, coupled with dissolution of calcareous microfossil assemblages, is possibly secondary and may represent lysocline shoaling in a nearshore environment. This would suggest that lysocline shoaling continued after the CIE and well into the early Eocene.

Dynamics of carbonate chemistry, production, and calcification of the Florida Reef Tract (2009-2010): Evidence for seasonal dissolution

NASA Astrophysics Data System (ADS)

Muehllehner, Nancy; Langdon, Chris; Venti, Alyson; Kadko, David

2016-05-01

Ocean acidification is projected to lower the Ωar of reefal waters by 0.3-0.4 units by the end of century, making it more difficult for calcifying organisms to secrete calcium carbonate while at the same time making the environment more favorable for abiotic and biotic dissolution of the reefal framework. There is great interest in being able to project the point in time when coral reefs will cross the tipping point between being net depositional to net erosional in terms of their carbonate budgets. Periodic in situ assessments of the balance between carbonate production and dissolution that spans seasonal time scales may prove useful in monitoring and formulating projections of the impact of ocean acidification on reefal carbonate production. This study represents the first broad-scale geochemical survey of the rates of net community production (NCP) and net community calcification (NCC) across the Florida Reef Tract (FRT). Surveys were performed at approximately quarterly intervals in 2009-2010 across seven onshore-offshore transects spanning the upper, middle, and lower Florida Keys. Averaged across the FRT, the rates of NCP and NCC were positive during the spring/summer at 62 ± 7 and 17 ± 2 mmol m-2 d-1, respectively, and negative during the fall/winter at -33 ± 6 and -7 ± 2 mmol m-2 d-1. The most significant finding of the study was that the northernmost reef is already net erosional (-1.1 ± 0.4 kg CaCO3 m-2 yr-1) and midreefs to the south were net depositional on an annual basis (0.4 ± 0.1 kg CaCO3 m-2 yr-1) but erosional during the fall and winter. Only the two southernmost reefs were net depositional year-round. These results indicate that parts of the FRT have already crossed the tipping point for carbonate production and other parts are getting close.

Tartaric Acid as a Non-toxic and Environmentally-Friendly Anti-scaling Material for Using in Cooling Water Systems: Electrochemical and Surface Studies

NASA Astrophysics Data System (ADS)

Asghari, Elnaz; Gholizadeh-Khajeh, Maryam; Ashassi-Sorkhabi, Habib

2016-10-01

Because of the major limitations in drinking water resources, the industries need to use unprocessed water sources for their cooling systems; these water resources contain major amount of hardening cations. So, mineral scales are formed in cooling water systems during the time and cause major problems. The use of green anti-scaling materials such as carboxylic acids is considered due to their low risks of environmental pollution. In the present work, the scale inhibition performance of tartaric acid as a green organic material was evaluated. Chemical screening tests, cathodic and anodic voltammetry measurements and electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray and x-ray diffraction, were used for the evaluation of the scale inhibition performance. The results showed that tartaric acid can prevent calcium carbonate precipitation significantly. The hard water solution with 2.0 mM of tartaric acid indicated the highest scale inhibition efficiency (ca. 68%). The voltammetry, EIS and FESEM results verified that tartaric acid can form smooth and homogeneous film on steel surface through formation of Fe(III)-tartrate complexes and retard the local precipitation of calcium carbonate deposits.

The effect of pigeon yolk sac fluid on the growth behavior of calcium carbonate crystals.

PubMed

Song, Juan; Cheng, Haixia; Shen, Xinyu; Tong, Hua

2015-03-01

Previous experiments have proved that thermodynamically unstable calcium carbonate vaterite can exist for long periods in the yolk sac of a pigeon embryo. The aim of this article was to demonstrate the effect of in vitro mineralization of yolk sac fluid on calcium carbonate by direct precipitation. Experiments were conducted using pigeon yolk sac fluid and using lecithin extracted from pigeon yolk sac fluid as a control to investigate the regulating effects of the organic components in the embryo on the formation of the calcium carbonate precipitate. Multiple characterization methods were employed to study the various morphological patterns, sizes, crystal growth, and crystal phase transformations of the calcium carbonate precipitates as regulated by the yolk sac fluid extracted at different stages of incubation. The experimental results demonstrate that as the incubation proceeds towards the later stages, the composition and environmental features of the yolk sac fluid become more favorable for the formation of relatively unstable calcium carbonate phases with high energies of the vaterite state. The experiments conducted with extracted lecithin as the template for crystal growth yielded similar results. A large amount of organic molecules with polar functional groups carried by the yolk sac fluid have strong effects and can both initially induce the crystallization and regulate the aggregation of calcium carbonate. Furthermore, this regulation process is found to be closely related to the lecithin contained in yolk sac fluid. These observations confirm the changes in yolk sac fluid composition during incubation have significant effects on the production of vaterite, which implicates the calcium transport during embryo growth. © 2015 Poultry Science Association Inc.

Effects of acid deposition on calcium nutrition and health of Southern Appalachian spruce fir forests

DOE Office of Scientific and Technical Information (OSTI.GOV)

McLaughlin, S.B.; Wullschleger, S.; Stone, A.

The role of acid deposition in the health of spruce fir forests in the Southern Appalachian Mountains has been investigated by a wide variety of experimental approaches during the past 10 years. These studies have proceeded from initial dendroecological documentation of altered growth patterns of mature trees to increasingly more focused ecophysiological research on the causes and characteristics of changes in system function associated with increased acidic deposition. Field studies across gradients in deposition and soil chemistry have been located on four mountains spanning 85 km of latitude within the Southern Appalachians. The conclusion that calcium nutrition is an importantmore » component regulating health of red spruce in the Southern Appalachians and that acid deposition significantly reduces calcium availability in several ways has emerged as a consistent result from multiple lines or research. These have included analysis of trends in wood chemistry, soil solution chemistry, foliar nutrition, gas exchange physiology, root histochemistry, and controlled laboratory and field studies in which acid deposition and/or calcium nutrition has been manipulated and growth and nutritional status of saplings or mature red spruce trees measured. This earlier research has led us to investigate the broader implications and consequences of calcium deficiency for changing resistance of spruce-fir forests to natural stresses. Current research is exploring possible relationships between altered calcium nutrition and shifts in response of Fraser fir to insect attack by the balsam wooly adelgid. In addition, changes in wood ultrastructural properties in relation to altered wood chemistry is being examined to evaluate its possible role in canopy deterioration, under wind and ice stresses typical of high elevation forests.« less

Hydrogen production from carbonaceous material

DOEpatents

Lackner, Klaus S.; Ziock, Hans J.; Harrison, Douglas P.

2004-09-14

Hydrogen is produced from solid or liquid carbon-containing fuels in a two-step process. The fuel is gasified with hydrogen in a hydrogenation reaction to produce a methane-rich gaseous reaction product, which is then reacted with water and calcium oxide in a hydrogen production and carbonation reaction to produce hydrogen and calcium carbonate. The calcium carbonate may be continuously removed from the hydrogen production and carbonation reaction zone and calcined to regenerate calcium oxide, which may be reintroduced into the hydrogen production and carbonation reaction zone. Hydrogen produced in the hydrogen production and carbonation reaction is more than sufficient both to provide the energy necessary for the calcination reaction and also to sustain the hydrogenation of the coal in the gasification reaction. The excess hydrogen is available for energy production or other purposes. Substantially all of the carbon introduced as fuel ultimately emerges from the invention process in a stream of substantially pure carbon dioxide. The water necessary for the hydrogen production and carbonation reaction may be introduced into both the gasification and hydrogen production and carbonation reactions, and allocated so as transfer the exothermic heat of reaction of the gasification reaction to the endothermic hydrogen production and carbonation reaction.

Method of purifying isosaccharinate

DOEpatents

Rai, Dhanpat; Moore, Robert C.; Tucker, Mark D.

2010-09-07

A method of purifying isosaccharinate by mixing sodium carbonate, potassium carbonate, sodium hydroxide or potassium hydroxide with calcium isosaccharinate, removing the precipitated calcium carbonate and adjusting the pH to between approximately 4.5 to 5.0 thereby removing excess carbonate and hydroxide to provide an acidic solution containing isosaccharinate.

Isolation and metagenomic characterization of bacteria associated with calcium carbonate and struvite precipitation in a pure moving bed biofilm reactor-membrane bioreactor.

PubMed

Gonzalez-Martinez, A; Leyva-Díaz, J C; Rodriguez-Sanchez, A; Muñoz-Palazon, B; Rivadeneyra, A; Poyatos, J M; Rivadeneyra, M A; Martinez-Toledo, M V

2015-01-01

A bench-scale pure moving bed bioreactor-membrane bioreactor (MBBR-MBR) used for the treatment of urban wastewater was analyzed for the identification of bacterial strains with the potential capacity for calcium carbonate and struvite biomineral formation. Isolation of mineral-forming strains on calcium carbonate and struvite media revealed six major colonies with a carbonate or struvite precipitation capacity in the biofouling on the membrane surface and showed that heterotrophic bacteria with the ability to precipitate calcium carbonate and struvite constituted ~7.5% of the total platable bacteria. These belonged to the genera Lysinibacillus, Trichococcus, Comamomas and Bacillus. Pyrosequencing analysis of the microbial communities in the suspended cells and membrane biofouling showed a high degree of similarity in all the samples collected with respect to bacterial assemblage. The study of operational taxonomic units (OTUs) identified through pyrosequencing suggested that ~21% of the total bacterial community identified in the biofouling could potentially form calcium carbonate or struvite crystals in the pure MBBR-MBR system used for the treatment of urban wastewater.

Role of magnesium on the biomimetic deposition of calcium phosphate

NASA Astrophysics Data System (ADS)

Sarma, Bimal K.; Sarma, Bikash

2016-10-01

Biomimetic depositions of calcium phosphate (CaP) are carried out using simulated body fluid (SBF), calcifying solution and newly developed magnesium containing calcifying solution. Calcium phosphate has a rich phase diagram and is well known for its excellent biocompatibility and bioactivity. The most common phase is hydroxyapatite (HAp), an integral component of human bone and tooth, widely used in orthopedic and dental applications. In addition, calcium phosphate nanoparticles show promise for the targeted drug delivery. The doping of calcium phosphate by magnesium, zinc, strontium etc. can change the protein uptake by CaP nanocrystals. This work describes the role of magnesium on the nucleation and growth of CaP on Ti and its oxide substrates. X-ray diffraction studies confirm formation of HAp nanocrystals which closely resemble the structure of bone apatite when grown using SBF and calcifying solution. It has been observed that magnesium plays crucial role in the nucleation and growth of calcium phosphate. A low magnesium level enhances the crystallinity of HAp while higher magnesium content leads to the formation of amorphous calcium phosphate (ACP) phase. Interestingly, the deposition of ACP phase is rapid when magnesium ion concentration in the solution is 40% of calcium plus magnesium ions concentration. Moreover, high magnesium content alters the morphology of CaP films.

Entrapment of carbon dioxide with chitosan-based core-shell particles containing changeable cores.

PubMed

Dong, Yanrui; Fu, Yinghao; Lin, Xia; Xiao, Congming

2016-08-01

Water-soluble chitosan-based core-shell particles that contained changeable cores were successfully applied to anchor carbon dioxide. The entrapment capacity of the particles for carbon dioxide (EC) depended on the cores. It was found that EC of the particles contained aqueous cores was higher than that of the beads with water-soluble chitosan gel cores, which was confirmed with thermogravimetric analysis. In addition, calcium ions and sodium hydroxide were introduced within the particles to examine their effect on the entrapment. EC of the particles was enhanced with sodium hydroxide when the cores were WSC gel. The incorporation of calcium ions was helpful for stabilizing carbon dioxide through the formation of calcium carbonate, which was verified with Fourier transform infrared spectra and scanning electron microscopy/energy-dispersive spectrometry. This phenomenon meant the role of calcium ions for fixating carbon dioxide was significant. Copyright © 2016 Elsevier B.V. All rights reserved.

[Study on solid dispersion of precipitated calcium carbonate-based oleanolic acid].

PubMed

Yan, Hong-mei; Zhang, Zhen-hai; Jia, Xiao-bin; Jiang, Yan-rong; Sun, E

2015-05-01

Oleanolic acid-precipitated calcium carbonate solid dispersion was prepared by using solvent evaporation method. The microscopic structure and physicochemical properties of solid dispersion were analyzed using differential scanning calorimetry and scanning electron microscopy (SEM). And its in vitro release also was investigated. The properties of the precipitated calcium carbonate was studied which was as a carrier of oleanolic acid solid dispersion. Differential scanning calorimetry analysis suggested that oleanolic acid may be present in solid dispersion as amorphous substance. The in vitro release determination results of oleanolic acid-precipitated calcium carbonate (1: 5) solid dispersion showed accumulated dissolution rate of.oleanolic acid was up to 90% at 45 min. Accelerating experiment showed that content and in vitro dissolution of oleanolic acid solid dispersion did not change after storing over 6 months. The results indicated that in vitro dissolution of oleanolic acid was improved greatly by the solid dispersion with precipitated calcium carbonate as a carrier. The solid dispersion is a stabilizing system which has actual applied value.

Synthesis of size-controlled acid-resistant hybrid calcium carbonate microparticles as templates for fabricating "micelles-enhanced" polyelectrolyte capsules by the LBL technique.

PubMed

Li, Xiaodong; Hu, Qiaoling; Yue, Linhai; Shen, Jiacong

2006-07-24

Size-controlled, low-dispersed calcium carbonate microparticles were synthesized in the presence of the amphiphilic block copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) by modulating the concentration of block copolymer in the reactive system. This type of hybrid microparticles have acid-resistant properties. By investigating the aggregation behaviors of PS-b-PAA micelles by transmission electron microscopy (TEM), the mechanism of hybrid calcium carbonate formation illustrated that the block copolymer served not only as "pseudonuclei" for the growth of calcium carbonate nanocrystals, but also forms the supramicelle congeries, a spherical framework, as templates for calcium carbonate nanocrystal growth into hybrid CaCO(3) particles. Moreover, this pilot study shows that the hybrid microparticle is a novel candidate as a template for fabricating multilayer polyelectrolyte capsules, in which the block copolymer is retained within the capsule interior after core removal under soft conditions. This not only facilitates the encapsulation of special materials, but also provides "micelles-enhanced" polyelectrolyte capsules.

Mineralized alginate hydrogels using marine carbonates for bone tissue engineering applications.

PubMed

Diaz-Rodriguez, P; Garcia-Triñanes, P; Echezarreta López, M M; Santoveña, A; Landin, M

2018-09-01

The search for an ideal bone tissue replacement has led to the development of new composite materials designed to simulate the complex inorganic/organic structure of bone. The present work is focused on the development of mineralized calcium alginate hydrogels by the addition of marine derived calcium carbonate biomineral particles. Following a novel approach, we were able to obtain calcium carbonate particles of high purity and complex micro and nanostructure dependent on the source material. Three different types of alginates were selected to develop inorganic/organic scaffolds in order to correlate alginate composition with scaffold properties and cell behavior. The incorporation of calcium carbonates into alginate networks was able to promote extracellular matrix mineralization and osteoblastic differentiation of mesenchymal stem cells when added at 7 mg/ml. We demonstrated that the selection of the alginate type and calcium carbonate origin is crucial to obtain adequate systems for bone tissue engineering as they modulate the mechanical properties and cell differentiation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Microalgal bacterial flocs treating paper mill effluent: A sunlight-based approach for removing carbon, nitrogen, phosphorus, and calcium.

PubMed

Van Den Hende, Sofie; Rodrigues, André; Hamaekers, Helen; Sonnenholzner, Stanislaus; Vervaeren, Han; Boon, Nico

2017-10-25

Treatment of upflow anaerobic sludge blanket (UASB) effluent from a paper mill in aerated activated sludge reactors involves high aeration costs. Moreover, this calcium-rich effluent leads to problematic scale formation. Therefore, a novel strategy for the aerobic treatment of paper mill UASB effluent in microalgal bacterial floc sequencing batch reactors (MaB-floc SBRs) is proposed, in which oxygen is provided via photosynthesis, and calcium is removed via bio-mineralization. Based on the results of batch experiments in the course of this study, a MaB-floc SBR was operated at an initial neutral pH. This SBR removed 58±21% organic carbon, 27±8% inorganic carbon, 77±5% nitrogen, 73±2% phosphorus, and 27±11% calcium. MaB-flocs contained 10±3% calcium, including biologically-influenced calcite crystals. The removal of calcium and inorganic carbon by MaB-flocs significantly decreased when inhibiting extracellular carbonic anhydrase (CA), an enzyme that catalyses the hydration and dehydration of CO 2 . This study demonstrates the potential of MaB-floc SBRs for the alternative treatment of calcium-rich paper mill effluent, and highlights the importance of extracellular CA in this treatment process. Copyright © 2017 Elsevier B.V. All rights reserved.

Increased river alkalinization in the Eastern U.S.

PubMed

Kaushal, Sujay S; Likens, Gene E; Utz, Ryan M; Pace, Michael L; Grese, Melissa; Yepsen, Metthea

2013-09-17

The interaction between human activities and watershed geology is accelerating long-term changes in the carbon cycle of rivers. We evaluated changes in bicarbonate alkalinity, a product of chemical weathering, and tested for long-term trends at 97 sites in the eastern United States draining over 260,000 km(2). We observed statistically significant increasing trends in alkalinity at 62 of the 97 sites, while remaining sites exhibited no significant decreasing trends. Over 50% of study sites also had statistically significant increasing trends in concentrations of calcium (another product of chemical weathering) where data were available. River alkalinization rates were significantly related to watershed carbonate lithology, acid deposition, and topography. These three variables explained ~40% of variation in river alkalinization rates. The strongest predictor of river alkalinization rates was carbonate lithology. The most rapid rates of river alkalinization occurred at sites with highest inputs of acid deposition and highest elevation. The rise of alkalinity in many rivers throughout the Eastern U.S. suggests human-accelerated chemical weathering, in addition to previously documented impacts of mining and land use. Increased river alkalinization has major environmental implications including impacts on water hardness and salinization of drinking water, alterations of air-water exchange of CO2, coastal ocean acidification, and the influence of bicarbonate availability on primary production.

Skeletal mineralogy of newly settling Acropora millepora (Scleractinia) coral recruits

NASA Astrophysics Data System (ADS)

Clode, P. L.; Lema, K.; Saunders, M.; Weiner, S.

2011-03-01

Knowledge of skeletogenesis in scleractinian corals is central to reconstructing past ocean and climate histories, assessing and counteracting future climate and ocean acidification impacts upon coral reefs, and determining the taxonomy and evolutionary path of the Scleractinia. To better understand skeletogenesis and mineralogy in extant scleractinian corals, we have investigated the nature of the initial calcium carbonate skeleton deposited by newly settling coral recruits. Settling Acropora millepora larvae were sampled daily for 10 days from initial attachment, and the carbonate mineralogy of their newly deposited skeletons was investigated. Bulk analyses using Raman and infrared spectroscopic methods revealed that the skeletons were predominantly comprised of aragonite, with no evidence of calcite or an amorphous precursor phase, although presence of the latter cannot be discounted. Sensitive selected area electron diffraction analyses of sub-micron areas of skeletal regions further consolidated these data. These findings help to address the uncertainty surrounding reported differences in carbonate mineralogy between larval and adult extant coral skeletons by indicating that skeletons of new coral recruits share the same aragonitic mineralogy as those of their mature counterparts. In this respect, we can expect that skeletogenesis in both larval and mature growth stages of scleractinian corals will be similarly affected by ocean acidification and predicted environmental changes.

In vitro study of the effect of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate on acid-softened enamel.

PubMed

Rege, Aarti; Heu, Rod; Stranick, Michael; Sullivan, Richard J

2014-01-01

To investigate the possible mode of action of a dentifrice containing 8% arginine and calcium carbonate (Pro-Argin Technology), and sodium monofluorophosphate in delivering the benefits of preventing acid erosion and rehardening acid-softened enamel. The surfaces of acid-softened bovine enamel specimens were evaluated after application of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate in vitro. Scanning Electron Microscopy (SEM), Electronic Spectrometry for Chemical Analysis (ESCA), and Secondary Ion Mass Spectrometry (SIMS) were used to characterize the enamel surfaces. Exposure of pristine enamel surfaces to citric acid resulted in clear roughening of the surface. Multiple applications of a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate to the surface of the enamel resulted in the disappearance of the microscopic voids observed by SEM as a function of treatment applications. The ESCA analysis demonstrated that both the nitrogen and carbonate levels increased as the number of treatments increased, which provides evidence that arginine and calcium carbonate were bound to the surface. Observance of arginine's signature mass fragmentation pattern by SIMS analysis confirmed the identity of arginine on the enamel surface. A series of in vitro experiments has demonstrated a possible mode of action by which a dentifrice containing 8% arginine, calcium carbonate, and sodium monofluorophosphate delivers the benefits of preventing acid erosion and rehardening acid-softened enamel. The combination of arginine and calcium carbonate adheres to the enamel surface and helps to fill the microscopic gaps created by acid, which in turn helps repair the enamel and provides a protective coating against future acid attacks.

Criteria to aid in the establishment of genetic boundaries within a carboniferous basin: Mary Lee Coal Zone, Black Warrior Basin, Alabama

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bryant, T.W.; Gastaldo, R.A.

The upper part of the Mary Lee coal zone of the Lower Pennsylvanian (Westphalian A) Pottsville Formation in northwestern Alabama is composed of the Mary Lee and the Newcastle coal seams. The Mary Lee coal seam has been economically significant in terms of both mining and coal-bed methane production. A sedimentological, paleontological, and geochemical investigation of the lithologies associated with this coal zone was done to define the changes that occur in facies changing from terrestrial into marine facies. A ravinement bed, ranging in thickness from 13.0 deposits. Fifteen surficially exposed sections were observed and sampled in the study area.more » Geochemical analyses were done on samples collected from seven sections along the perimeter of the study area. The analyses conducted involved inductively coupled atomic plasma spectrometry (ICAP) for seven elemental oxides that include aluminum, iron, silica, calcium, potassium, magnesium and manganese. Atomic absorption was used to determine sodium content. Carbonate carbon was determined by weight percent difference after hydrochloric acid treatment, whereas organic carbon content was determined by use of a carbon analyzer on a LECO[sup TM] induction furnace. Sulfur content was also determined by a LECO induction furnace equipped with a sulfur analyzer. Loss-on-ignition (LOI) percentage was based upon change in weight of samples after a period of 30 min in a muffle furnace at a temperature of 1000[degrees]C. The combination of sedimentological, paleontological, and geochemical characteristics were used to better understand the depositional setting of the upper Mary Lee coal zone in terms of a transgressive event. These criteria can be used in similar basin systems to better understand the depositional history of those settings.« less

Perlwapin, an Abalone Nacre Protein with Three Four-Disulfide Core (Whey Acidic Protein) Domains, Inhibits the Growth of Calcium Carbonate Crystals

PubMed Central

Treccani, Laura; Mann, Karlheinz; Heinemann, Fabian; Fritz, Monika

2006-01-01

We have isolated a new protein from the nacreous layer of the shell of the sea snail Haliotis laevigata (abalone). Amino acid sequence analysis showed the protein to consist of 134 amino acids and to contain three sequence repeats of ∼40 amino acids which were very similar to the well-known whey acidic protein domains of other proteins. The new protein was therefore named perlwapin. In addition to the major sequence, we identified several minor variants. Atomic force microscopy was used to explore the interaction of perlwapin with calcite crystals. Monomolecular layers of calcite crystals dissolve very slowly in deionized water and recrystallize in supersaturated calcium carbonate solution. When perlwapin was dissolved in the supersaturated calcium carbonate solution, growth of the crystal was inhibited immediately. Perlwapin molecules bound tightly to distinct step edges, preventing the crystal layers from growing. Using lower concentrations of perlwapin in a saturated calcium carbonate solution, we could distinguish native, active perlwapin molecules from denaturated ones. These observations showed that perlwapin can act as a growth inhibitor for calcium carbonate crystals in saturated calcium carbonate solution. The function of perlwapin in nacre growth may be to inhibit the growth of certain crystallographic planes in the mineral phase of the polymer/mineral composite nacre. PMID:16861275

Phase transitions in biogenic amorphous calcium carbonate

NASA Astrophysics Data System (ADS)

Gong, Yutao

Geological calcium carbonate exists in both crystalline phases and amorphous phases. Compared with crystalline calcium carbonate, such as calcite, aragonite and vaterite, the amorphous calcium carbonate (ACC) is unstable. Unlike geological calcium carbonate crystals, crystalline sea urchin spicules (99.9 wt % calcium carbonate and 0.1 wt % proteins) do not present facets. To explain this property, crystal formation via amorphous precursors was proposed in theory. And previous research reported experimental evidence of ACC on the surface of forming sea urchin spicules. By using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), we studied cross-sections of fresh sea urchin spicules at different stages (36h, 48h and 72h after fertilization) and observed the transition sequence of three mineral phases: hydrated ACC → dehydrated ACC → biogenic calcite. In addition, we unexpectedly found hydrated ACC nanoparticles that are surrounded by biogenic calcite. This observation indicates the dehydration from hydrated ACC to dehydrated ACC is inhibited, resulting in stabilization of hydrated ACC nanoparticles. We thought that the dehydration was inhibited by protein matrix components occluded within the biomineral, and we designed an in vitro assay to test the hypothesis. By utilizing XANES-PEEM, we found that SM50, the most abundant occluded matrix protein in sea urchin spicules, has the function to stabilize hydrated ACC in vitro.

EPS composition and calcification potential of tufa-dominating cyanobacteria investigated by Scanning Transmission X-ray Microscopy (STXM) and Laser Scanning Microscopy (LSM)

NASA Astrophysics Data System (ADS)

Zippel, Barbara; Dynes, James J.; Obst, Martin; Lawrence, John R.; Neu, Thomas R.

2010-05-01

Tufa deposits in freshwater habitats are the result of calcium carbonate precipitation within interfacial microbial ecosystems. Calcite precipitation is influenced by the saturation index and the occurrence of extracellular polymeric substances (EPS) which are produced by a variety of microorganisms. In theory, the first important step of biologically induced calcification processes is the adsorption of calcium ions by extracellular polymeric substances (EPS) produced by cyanobacteria. In the present study we take advantage of Laser Scanning Microscopy (LSM) and combine it with Synchrotron imaging using Scanning Transmission X-ray Microscopy (STXM). STXM represents a technique that allows simultaneous analysis of inorganic and organic constituents as a scale of 50 nm. By means of STXM it is possible to differentiate between calcium carbonate phases at the Ca L-edge. Furthermore, STXM has also been used at the C K-edge to map the major biomolecules (proteins, lipids, and polysaccharides). The purpose of this study is to find out if there are differences in calcium adsorption depending on specific composition of the EPS produced by filamentous cyanobacteria isolated from a German hard water creek (Westerhöfer Bach, Harz Mountains). The goal was to elucidate the potential of biofilms constituents, including microbial cell surfaces as well as extracellular polymeric substances, in triggering the formation of calcium carbonate in tufa systems. For this purpose three filamentous cyanobacteria (Pseudanabaena sp., Leptolyngbya sp. and Nostoc sp.) were cultivated in creek-adapted as well as standard media (BG11) on polycarbonate slides. In situ EPS composition was detected by means of fluorescence lectin-binding approach (FLBA) using 23 commercially available lectins with different specificities for mono- and disaccharides and amino sugars. For CaCO3 nucleation experiments cyanobacterial biofilms grown on polycarbonate slides were deposited in NaHCO3/CaCl2 solutions supersaturated 10 times with respect to calcite for 48, 72 and 144 hours. For the STXM experiment on beamline 10-ID1 at the Canadian Light Source (CLS), the biofilm samples were scrapped off, suspended in a slurry and deposited carefully on a Si3N4 window. In order to obtain quantitative speciation maps of cyanobacterial sheath EPS, image sequences (stacks) were recorded at the C-1s (280-320 eV) and Ca-2p (340-360 eV) edges. Data analysis was done by using the software aXis2000, and energy spectra were fitted with available reference spectra. Nearly the same lectins specific for fucose, mannose, N-acetylgalactosamine and N-acetylglucosamine, as well as sialic acid bound preferentially to the EPS of cyanobacterial sheaths of Pseudanabaena sp. and Leptolyngbya sp. Surprisingly, in case of Nostoc sp. only two lectins specific for fucose, and N-acetylgalactosamine showed a clear binding to the EPS of sheaths. Qualitative, lectin-specific EPS composition was not influenced by nutrient concentrations within the medium during cultivation. In order to biochemically characterize the CaCO3 nucleation sites within the sheaths of the cyanobacteria investigated, carbon maps of the most abundant organic components were derived from C-1s image sequences. The sheaths of the cyanobacteria contained mainly polysaccharides followed by proteins, and a small amount of lipids. The highest amount of polysaccharides was detected in EPS produced by Pseudanabaena sp., whereas in Nostoc sp. only one-fifth was found. All samples investigated contained spectral signatures of Ca2+ adsorbed to EPS. Aragonite-like CaCO3 was detected in close association with the cell surface of Leptolyngbya sp. only. Highest amount of adsorbed Ca to EPS was found in Pseudanabaena sp., whereas only one-third was detected within the EPS of sheaths in Leptolyngbya sp. and Nostoc sp. Results of this combined approach show that the cyanobacteria investigated are may be involved in calcification processes to different degrees.

Increased Calcium Availability Leads to Greater Forest Floor Accumulation in an Adirondack Forest

NASA Astrophysics Data System (ADS)

Melvin, A.; Goodale, C. L.

2010-12-01

Nutrient availability in Northeastern US forests has been dramatically altered by anthropogenic activities. Acid deposition has not only increased nitrogen (N) availability, but has also been linked to soil acidification and a loss of base cations, largely calcium (Ca). We are studying the long-term effects of a Ca addition on carbon (C) and N cycling in a forested catchment in the Adirondack Park, New York. In 1989, calcium carbonate (lime) was added to two subcatchments within the Woods Lake Watershed to ameliorate the effects of soil Ca depletion. Two additional subcatchments were left as controls. Eighteen years after the Ca application, both soil pH and exchangeable Ca concentrations remain elevated in the organic horizons and upper mineral soils of the treated subcatchments. The forest floor mass in this watershed is very large and measurements show that the organic layer in the limed subcatchments is significantly larger than in the controls (212 t/ha vs. 116 t/ha), resulting in greater C and N stocks in the Ca-amended soils. This finding suggests that Ca may stabilize soil organic matter (SOM), resulting in greater C storage under high soil Ca conditions. We are investigating potential drivers of this SOM accumulation in the limed subcatchments, including rates of leaf litter production and the decomposition rate of forest floor material. This work will provide important insights into how long-term changes in soil Ca availability influence SOM stabilization, retention and nutrient cycling.

Plasma oxalic acid and calcium levels in oxalate poisoning

PubMed Central

Zarembski, P. M.; Hodgkinson, A.

1967-01-01

Observations are reported on five cases of suicide or attempted suicide by poisoning with oxalic acid or ethylene glycol. Elevated oxalic acid levels were observed in the plasma, stomach contents, and a number of tissues. Raised oxalic acid levels in plasma were associated with reduced total and ultrafilterable calcium levels. It is suggested that the reduction in plasma total calcium level is due mainly to the deposition of calcium oxalate in the soft tissues, but inhibition of the parathyroid glands may be a contributory factor. Microscopic examination of various tissues indicated that oxalic acid is deposited in the tissues in two forms: (1) crystalline calcium oxalate dihydrate in the kidney and (2) a non-crystalline complex of calcium oxalate and lipid in liver and other tissues. PMID:5602563

Absorption of Levothyroxine When Coadministered with Various Calcium Formulations

PubMed Central

Zamfirescu, Isabelle

2011-01-01

Background Calcium carbonate is a commonly used dietary supplement and has been shown to interfere with levothyroxine absorption. However, calcium citrate, which is also used for supplementation purposes, has not been studied previously and calcium acetate, which is used to treat hyperphosphatemia in renal failure, has been reported to show little or no interference with levothyroxine absorption in a retrospective pharmacoepidemiologic study. We aimed to compare the effect of these three calcium formulations on levothyroxine absorption. Materials and Methods The study was conducted in eight healthy, euthyroid adults. We performed single-dose pharmacokinetic studies in which we measured levothyroxine absorption when given alone or when coadministered with calcium carbonate, calcium citrate, or calcium acetate in doses containing 500 mg elemental calcium. Serum thyroxine was measured at intervals over a 6-hour period after ingestion of the study drugs. Results Coadministration of each of the three calcium preparations significantly reduced levothyroxine absorption by about 20%–25% compared with levothyroxine given alone. Conclusions Contrary to a prior report, our data suggest that calcium acetate interferes with levothyroxine absorption in a manner similar to that seen with calcium carbonate and calcium citrate. Although the effect of calcium is modest compared with some other medications previously studied, hypothyroid patients should be cautioned to take their levothyroxine well-separated from all of these calcium formulations. PMID:21595516

Calcium Acetate or Calcium Carbonate for Hyperphosphatemia of Hemodialysis Patients: A Meta-Analysis

PubMed Central

Zhang, Han; Yang, Bo; Mao, Zhiguo

2015-01-01

Background High levels of serum phosphorus both at baseline and during follow-up are associated with increased mortality in dialysis patients, and administration of phosphate binders was independently associated with improved survival among hemodialysis population. Calcium-based phosphate binders are the most commonly used phosphate binders in developing countries for their relatively low costs. Objectives To compare the efficacy and safety between calcium carbonate and calcium acetate in the treatment of hyperphosphatemia in hemodialysis patients. Methods PubMed, EMBASE, Cochrane Library, Google scholar and Chinese databases (Wanfang, Weipu, National Knowledge Infrastructure of China) were searched for relevant studies published before March 2014. Reference lists of nephrology textbooks and review articles were checked. A meta-analysis of randomized controlled trials (RCTs) and quasi-RCTs that assessed the effects and adverse events of calcium acetate and calcium carbonate in adult patients with MHD was performed using Review Manager 5.0. Results A total of ten studies (625 participants) were included in this meta-analysis. There was insufficient data in all-cause mortality and cardiovascular events for meta-analysis. Compared with calcium carbonate group, the serum phosphorus was significantly lower in calcium acetate group after4 weeks’ administration (MD -0.15 mmol/L, 95% CI -0.28 to -0.01) and after 8 weeks’ administration (MD -0.25 mmol/L, 95% CI -0.40 to -0.11). There was no difference in serum calcium levels or the incidence of hypercalcemia between two groups at 4 weeks and 8 weeks. No statistical difference was found in parathyroid hormone (PTH) levels or serum calcium by phosphorus (Ca x P) product. There was significantly higher risk of intolerance with calcium acetate treatment (RR 3.46, 95% CI 1.48 to 8.26). Conclusions For hyperphosphatemia treatment, calcium acetate showed better efficacy and with a higher incidence of intolerance compared with calcium carbonate. There are insufficient data to establish the comparative superiority of the two calcium-based phosphate binders on all-cause mortality and cardiovascular end-points in hemodialysis patients. PMID:25799184

Intensified Vegetation Water Use due to Soil Calcium Leaching under Acid Deposition

NASA Astrophysics Data System (ADS)

Lanning, M.; Wang, L.; Scanlon, T. M.; Vadeboncoeur, M. A.; Adams, M. B.; Epstein, H. E.; Druckenbrod, D.

2017-12-01

Despite the important role vegetation plays in the global water cycle, the exact controls of vegetation water use, especially the role of soil biogeochemistry, remain elusive. Nitrate and sulfate deposition from fossil fuel burning has caused significant soil acidification, leading to the leaching of soil base cations. From a physiological perspective, plants require various soil cations as signaling and regulatory ions as well as integral parts of structural molecules; a depletion of soil cations can cause reduced productivity and abnormal responses to environmental change. A deficiency in calcium could also potentially prolong stomatal opening, leading to increased transpiration until enough calcium had been acquired to stimulate stomatal closure. Based on the plant physiology and the nature of acidic deposition, we hypothesize that depletion of the soil calcium supply, induced by acid deposition, would intensify vegetation water use at the watershed scale. We tested this hypothesis by analyzing a long-term and unique data set (1989-2012) of soil lysimeter data along with stream flow and evapotranspiration data at the Fernow Experimental Forest. We show that depletion of soil calcium by acid deposition can intensify vegetation water use ( 10% increase in evapotranspiration and depletion in soil water) for the first time. These results are critical to understanding future water availability, biogeochemical cycles, and surficial energy flux and may help reduce uncertainties in terrestrial biosphere models.

Solubility and bioavailability of stabilized amorphous calcium carbonate.

PubMed

Meiron, Oren E; Bar-David, Elad; Aflalo, Eliahu D; Shechter, Assaf; Stepensky, David; Berman, Amir; Sagi, Amir

2011-02-01

Since its role in the prevention of osteoporosis in humans was proven some 30 years ago, calcium bioavailability has been the subject of numerous scientific studies. Recent technology allowing the production of a stable amorphous calcium carbonate (ACC) now enables a bioavailability analysis of this unique form of calcium. This study thus compares the solubility and fractional absorption of ACC, ACC with chitosan (ACC-C), and crystalline calcium carbonate (CCC). Solubility was evaluated by dissolving these preparations in dilute phosphoric acid. The results demonstrated that both ACC and ACC-C are more soluble than CCC. Fractional absorption was evaluated by intrinsically labeling calcium carbonate preparations with (45)Ca, orally administrated to rats using gelatin capsules. Fractional absorption was determined by evaluating the percentage of the administrated radioactive dose per milliliter that was measured in the serum, calcium absorption in the femur, and whole-body retention over a 34-hour period. Calcium serum analysis revealed that calcium absorption from ACC and ACC-C preparations was up to 40% higher than from CCC, whereas retention of ACC and ACC-C was up to 26.5% higher than CCC. Absorbed calcium in the femurs of ACC-administrated rats was 30% higher than in CCC-treated animals, whereas 15% more calcium was absorbed following ACC-C treatment than following CCC treatment. This study demonstrates the enhanced solubility and bioavailability of ACC over CCC. The use of stable ACC as a highly bioavailable dietary source for calcium is proposed based on the findings of this study. Copyright © 2011 American Society for Bone and Mineral Research.

Atmospheric deposition as a source of carbon and nutrients to barren, alpine soils of the Colorado Rocky Mountains

NASA Astrophysics Data System (ADS)

Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Cawley, K.

2012-03-01

Many alpine areas are experiencing intense deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, we evaluated the magnitude and chemical quality of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long term dataset (2002-2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were approximately 1.0 mg L-1and weekly concentrations reached peaks as high at 6-10 mg L-1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. Relationships among DOC concentration, dissolved organic matter (DOM) fluorescence properties, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples and, therefore, likely to be more bioavailable to microbes in barren alpine soils. Bioavailability experiments with different types of atmospheric C sources are needed to better evaluate the substrate quality of atmospheric C inputs. Our C budget estimates for the Green Lake 4 catchment suggest that atmospheric deposition represents an average input of approximately 13 kg C ha-1 yr-1 that could be as high as 24 kg C ha-1 yr-1 in high dust years and approaches that of autotrophic C fixation in barren soils.

Results of the TTF-TCNQ and the calcium carbonate crystallization on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Nielsen, Kjeld Flemming; Lind, M. David

1992-01-01

Experiment A0139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit five years with crystal growth solutions for lead sulfide, calcium carbonate, and TTF-TCNQ. Although temperature data was lost, the experimental program had been working since the valves in all containers had been opened. All four experiments produced crystals of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X ray investigations as well as conductivity measurements on long duration space grown TTF-TCNQ crystals will be presented. Comparisons will be made with our previous space solution growth experiments. The TTF-TCNQ crystals are no longer of the highest interest, so this activity has been terminated in favor of calcium carbonate and calcium phosphate crystallizations.

Immobilization of Pseudomonas sp. DG17 onto sodium alginate–attapulgite–calcium carbonate

PubMed Central

Wang, Hong Qi; Hua, Fei; Zhao, Yi Cun; Li, Yi; Wang, Xuan

2014-01-01

A strain of Pseudomonas sp. DG17, capable of degrading crude oil, was immobilized in sodium alginate–attapulgite–calcium carbonate for biodegradation of crude oil contaminated soil. In this work, proportion of independent variables, the laboratory immobilization parameters, the micromorphology and internal structure of the immobilized granule, as well as the crude oil biodegradation by sodium alginate–attapulgite–calcium carbonate immobilized cells and sodium alginate–attapulgite immobilized cells were studied to build the optimal immobilization carrier and granule-forming method. The results showed that the optimal concentrations of sodium alginate–attapulgite–calcium carbonate and calcium chloride were 2.5%–3.5%, 0.5%–1%, 3%–7% and 2%–4%, respectively. Meanwhile, the optimal bath temperature, embedding cell amount, reaction time and multiplication time were 50–60 °C, 2%, 18 h and 48 h, respectively. Moreover, biodegradation was enhanced by immobilized cells with a total petroleum hydrocarbon removal ranging from 33.56% ± 3.84% to 56.82% ± 3.26% after 20 days. The SEM results indicated that adding calcium carbonate was helpful to form internal honeycomb-like pores in the immobilized granules. PMID:26019567

The influence of scale inhibitors on calcium oxalate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, J.S.

1999-11-01

Precipitation of calcium oxalate is a common occurrence in mammalian urinary tract deposits and in various industrial processes such as paper making, brewery fermentation, sugar evaporation, and tannin concentration. Between pH 3.5 to 4.5 the driving force for calcium oxalate precipitation increases almost by three fold. It is a complicated process to predict both the nature of a deposit and at which stage of a multi-effect evaporator a particular mineral will deposit, as this depends on temperature, pH, total solids, and kinetics of mineralization. It is quite a challenge to inhibit calcium oxalate precipitation in the pH range of 4--6.more » Al{sup 3+} ions provide excellent threshold inhibition in this pH range and can be used to augment traditional inhibitors such as polyphosphates and polycarboxylates.« less

Obtaining and Characterization of Polyolefin-Filled Calcium Carbonate Composites Modified with Stearic Acid

NASA Astrophysics Data System (ADS)

Croitoru, C.; Pascu, A.; Roata, I. C.; Stanciu, E. M.

2017-06-01

In order to obtain high performance calcium carbonate-reinforced HDPE and PP composites, the dispersibility and compatibility of the inorganic phase in the polymer has been achieved through surface treatment of the amorphous calcium carbonate filler with stearic acid. The surface coating of the inorganic phase has been proved by XRD and FTIR spectroscopy, through forming of an intermediate layer of calcium stearate which acts as a surfactant, efficient in providing an optimum compatibility with the dominatingly hydrophobic polymer matrix, as determined from the structural information obtained through samples cross-sections analysing.

Origin and chemical composition of evaporite deposits

USGS Publications Warehouse

Moore, George William

1960-01-01

A comparative study of marine evaporite deposits forming at the present time along the pacific coast of central Mexico and evaporite formations of Permian age in West Texas Basin was made in order to determine if the modern sediments provide a basis for understanding environmental conditions that existed during deposition of the older deposits. The field work was supplemented by investigations of artificial evaporite minerals precipitated in the laboratory and by study of the chemical composition of halite rock of different geologic ages. The environment of deposition of contemporaneous marine salt deposits in Mexico is acidic, is strongly reducing a few centimeters below the surface, and teems with microscopic life. Deposition of salt, unlike that of many other sediments, is not wholly a constructional phenomenon. Permanent deposits result only if a favorable balance exists between deposition in the dry season and dissolution in the wet season. Evaporite formations chosen for special study in the West Texas Basin are, in ascending order, the Castile, Salado, and Rustler formations, which have a combined thickness of 1200 meters. The Castile formation is largely composed of gypsum rock, the Salado, halite rock, and the Rustler, quartz and carbonate sandstone. The lower part of the Castile formation is bituminous and contains limestone laminae. The Castile and Rustler formations thicken to the south at the expense of salt of the intervening Salado formation. The clastic rocks of the Rustler formation are interpreted as the deposits of a series of barrier islands north of which halite rock of the Salado was deposited. The salt is believed to have formed in shallow water of uniform density that was mixed by the wind. Where water depth exceeded the depth of the wind mixing, density stratification developed, and gypsum was deposited. Dense water of high salinity below the density discontinuity was overlain by less dense, more normally saline water which was derived from the sea to the south. Mixing of the two water layers at their interface diluted the lower layer so as to prevent halite formation, but at the same time the depressed solubility of calcium sulfate in the mixture at the interface caused precipitation of gypsum. The upper water layer is believed to have supported a flourishing microscopic biota whose remains descended into semisterile brine below where reducing conditions prevailed. This environment generated the bituminous gypsum rock. At times, microcrystalline calcium carbonate of probable biochemical origin formed in the upper layer and settled below to form limestone laminae such as those of the lower part of the Castile formation. Chemical analyses of Permian and present-day salt were compared with analyses of marine salt as old as Cambrian age to determine if evaporite deposits can contribute information on the geologic history of sea water. The results contain uncertainties that cannot be fully resolved, but they suggest that the ratio between ions in sea water has been approximately constant since Precambrian time. In addition, the abrupt initial appearance of rock salt deposits in Cambrian time suggests that the Precambrian ocean may have been rather dilute, but this apparent relationship also could have been caused by other factors.

Calcium Carbonate.

PubMed

Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

2016-01-01

Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables. © 2016 Elsevier Inc. All rights reserved.

Nicotine-substitute gum-induced milk alkali syndrome: a look at unexpected sources of calcium.

PubMed

Swanson, Christine M; Mackey, Patricia A; Westphal, Sydney A; Argueta, Rodolfo

2013-01-01

This report describes a 64-year-old woman with recurrent hypercalcemia. Her laboratory evaluation was consistent with milk-alkali syndrome. It was eventually discovered that the source of the excessive calcium consumption was nicotine-replacement chewing gum and carbonated water. An extensive literature search was performed to see if milk-alkali syndrome due to nicotine-replacement gum and carbonated water has been previously reported. No prior report describing the association of milk alkali syndrome with nicotine-replacement gum and carbonated water was found. We present a unique case of milk-alkali syndrome due to nicotine-replacement gum and carbonated water. It serves as a lesson to evaluate other sources besides calcium supplements as the cause of excessive calcium intake.

Calcination of calcium carbonate and blend therefor

DOEpatents

Mallow, William A.; Dziuk, Jr., Jerome J.

1989-01-01

A method for calcination of a calcium carbonate material comprising heating the calcium carbonate material to a temperature and for a time sufficient to calcine the material to the degree desired while in the presence of a catalyst; said catalyst comprising at least one fused salt having the formula MCO.sub.3.CaCO.sub.3.CaO.H.sub.2 O.sub.x, wherein M is an alkali metal and x is 0 to 1 and formed by fusing MCO.sub.3 and CaCO.sub.3 in a molar ratio of about 1:2 to 2:1, and a blend adapted to be heated to CaO comprising a calcium carbonate material and at least one such fused salt.

Urbanization impact on sulfur content of groundwater revealed by the study of urban speleothem-like deposits: Case study in Paris, France.

PubMed

Pons-Branchu, E; Roy-Barman, M; Jean-Soro, L; Guillerme, A; Branchu, P; Fernandez, M; Dumont, E; Douville, E; Michelot, J L; Phillips, A M

2017-02-01

Speleothem-like deposits that develop underground in urban areas are an archive of the environmental impact of anthropic activities that has been little studied so far. In this paper, the sulfate content in shallow groundwater from northern Paris (France) is compared with the sulfur content in two 300-year-old urban carbonate deposits that grew in a historical underground aqueduct. The present-day waters of the aqueduct have very high sulfur and calcium contents, suggesting pollution from gypsum dissolution. However, geological gypsum levels are located below the water table. Sulfur content was measured by micro-X-ray fluorescence in these very S-rich carbonate deposits (0.5 to 1% of S). A twofold S increase during the second half of the 1800s was found in both samples. These dates correspond to two major periods of urbanization above the site. We discus three possible S sources: anthropic sources (industries, fertilizers…), volcanic eruptions and input within the water through gypsum brought for urbanization above the studied site (backfill with quarry waste) since the middle of the 19th century. For the younger second half of the studied section, S input from gypsum brought during urbanization was confirmed by the study of isotopic sulfur composition (δ 34 S=+15.2‰ at the top). For the oldest part, several sulfur peaks could be related to early industrial activity in Paris, that caused high local air pollution, as reported in historical archives but also to historical gypsum extraction. This study provides information on the origin and timing of the very high SO 4 2- levels measured nowadays within the shallow groundwater, thus demonstrating the interest in using carbonate deposits in urban areas as a proxy for the history of urbanization or human activities and their impact on water bodies. Copyright © 2016 Elsevier B.V. All rights reserved.

Coral reef sedimentation on Rodrigues and the Western Indian Ocean and its impact on the carbon cycle.

PubMed

Rees, Siwan A; Opdyke, Bradley N; Wilson, Paul A; Fifield, L Keith

2005-01-15

Coral reefs in the southwest Indian Ocean cover an area of ca. 18,530 km2 compared with a global reef area of nearly 300,000 km2. These regions are important as fishing grounds, tourist attractions and as a significant component of the global carbon cycle. The mass of calcium carbonate stored within Holocene neritic sediments is a number that we are only now beginning to quantify with any confidence, in stark contrast to the mass and sedimentation rates associated with pelagic calcium carbonate, which have been relatively well defined for decades. We report new data that demonstrate that the reefs at Rodrigues, like those at Reunion and Mauritius, only reached a mature state (reached sea level) by 2-3 ka: thousands of years later than most of the reefs in the Australasian region. Yet field observations show that the large lagoon at Rodrigues is already completely full of carbonate detritus (typical lagoon depth less than 1 m at low spring tide). The presence of aeolian dunes at Rodrigues indicates periodic exposure of past lagoons throughout the Pleistocene. The absence of elevated Pleistocene reef deposits on the island indicates that the island has not been uplifted. Most Holocene reefs are between 15 and 20 m in thickness and those in the southwest Indian Ocean appear to be consistent with this observation. We support the view that the CO2 flux associated with coral-reef growth acts as a climate change amplifier during deglaciation, adding CO2 to a warming world. southwest Indian Ocean reefs could have added 7-10% to this global flux during the Holocene.

Pharmacokinetics of Dolutegravir When Administered With Mineral Supplements in Healthy Adult Subjects

PubMed Central

Song, Ivy; Borland, Julie; Arya, Niki; Wynne, Brian; Piscitelli, Stephen

2015-01-01

All commercially available integrase inhibitors are 2-metal binders and may be affected by co-administration with metal cations. The purpose of this study was to evaluate the effect of calcium and iron supplements on dolutegravir pharmacokinetics and strategies (dose separation and food) to attenuate the effects if significant reductions in dolutegravir exposure were observed. This was an open-label, crossover study that randomized 24 healthy subjects into 1 of 2 cohorts to receive 4 treatments: (1) dolutegravir alone, fasting; (2) dolutegravir with calcium carbonate or ferrous fumarate, fasting; (3) dolutegravir with calcium carbonate or ferrous fumarate with a moderate-fat meal; (4) dolutegravir administered 2 hours before calcium carbonate or ferrous fumarate, fasting. Plasma dolutegravir AUC(0–∞), Cmax, and C24 were reduced by 39%, 37%, and 39%, respectively, when co-administered with calcium carbonate while fasting and were reduced by 54%, 57%, and 56%, respectively, when co-administered with ferrous fumarate while fasting. Dolutegravir administration 2 hours before calcium or iron supplement administration (fasted), as well as administration with a meal, counteracted the effect. Dolutegravir and calcium or iron supplements can be co-administered if taken with a meal. Under fasted conditions, dolutegravir should be administered 2 hours before or 6 hours after calcium or iron supplements. PMID:25449994

Carbonate deposition, Pyramid Lake subbasin, Nevada: 1. Sequence of formation and elevational distribution of carbonate deposits (Tufas)

USGS Publications Warehouse

Benson, L.

1994-01-01

During the late Quarternary, the elevation of terrace cutting and carbonate deposition in the Pyramid Lake subbasin were controlled by constancy of lake level imposed by spill to adjoining subbasins. Sill elevations are 1177-1183 m (Mud Lake Slough Sill), 1207 m (Emerson Pass Sill), and 1265 m (Darwin Pass Sill). Carbonate deposition was favored by: (1) hydrologic closure, (2) proximity to a source of calcium, (3) elevated water temperature, and (4) a solid substrate. The thickness and aspect of tufa are a function oflake-level dynamics. Relatively thin sheets and pendant sheets were deposited during a rising or falling lake. The upper parts of thick reef-form tufas have a horizontal aspect and were deposited in a lake which was stabilized by spill to the Carson Desert subbasin. The lower parts of the reef-form tufas are thinner and their outer surface has a vertical aspect, indicating that the lower part formed in a receding lake. The thickest and most complete sequences of tufa are mounds that border the Pyramid Lake shore. The tops of the tallest mounds reach the elevation of the Darwin Pass Sill and many mounds have been eroded to the elevations of the Mud Lake Slough Sill of the Emerson Pass Sill. The sequence of tufa formation (from oldest to youngest) displayed in these mounds is: (1) a beachrock containing carbonate-cemented volcanic cobbles, (2) broken and eroded old spheroids that contain thinolitic tufa and an outer rind of dense laminated tufa, (3) large cylindrical (tubular) tufas capped by (4) coatings of old dense tufas, and (5) several generations of old branching tufa commonly associated with thin, platy tufas and coatings of thinolitic tufa, (6) young spheroids that contain poorly oriented young thinolitic tufa in the center and several generations of radially oriented young thinolitic tufas near the outer edge, (7) a transitional thinolite-to-branching tufa, (8) two or more layers of young branching tufa, (9) a 0.5-cm-thick layer of fine-grained dolomite, (10) a 2-cm-thick layer of young dense laminated tufa, (11) a 0.1-cm-thick layer of encrusting tufa that was covered by a beach deposit and (12) a 1.0-cm-thick layer of porous encrusting tufa that coated the beach deposit and the sides of tufa mounds. The elevational ranges of the principal varieties of tufa are not related to terrace or spill elevations. It seems likely that the distribution of tufa varieties is related to variation in the thermal structure or chemistry of Lake Lahontan. It is hypothesized that the thinolitic tufa (ikaite) formed in the near freezing hypolimnion and the braching tufa (calcite) formed in the seasonally warmer epiliminion of the lake. ?? 1994.

Glycolytic intermediates induce amorphous calcium carbonate formation in crustaceans.

PubMed

Sato, Ai; Nagasaka, Seiji; Furihata, Kazuo; Nagata, Shinji; Arai, Isao; Saruwatari, Kazuko; Kogure, Toshihiro; Sakuda, Shohei; Nagasawa, Hiromichi

2011-04-01

It has been thought that phosphorus in biominerals made of amorphous calcium carbonate (ACC) might be related to ACC formation, but no such phosphorus-containing compounds have ever been identified. Crustaceans use ACC biominerals in exoskeleton and gastroliths so that they will have easy access to calcium carbonate inside the body before and after molting. We have identified phosphoenolpyruvate and 3-phosphoglycerate, intermediates of the glycolytic pathway, in exoskeleton and gastroliths and found them important for stabilizing ACC.

Biomineralization of calcium carbonates and their engineered applications: a review

PubMed Central

Dhami, Navdeep K.; Reddy, M. Sudhakara; Mukherjee, Abhijit

2013-01-01

Microbially induced calcium carbonate precipitation (MICCP) is a naturally occurring biological process in which microbes produce inorganic materials as part of their basic metabolic activities. This technology has been widely explored and promising with potential in various technical applications. In the present review, the detailed mechanism of production of calcium carbonate biominerals by ureolytic bacteria has been discussed along with role of bacteria and the sectors where these biominerals are being used. The applications of bacterially produced carbonate biominerals for improving the durability of buildings, remediation of environment (water and soil), sequestration of atmospheric CO2 filler material in rubbers and plastics etc. are discussed. The study also sheds light on benefits of bacterial biominerals over traditional agents and also the issues that lie in the path of successful commercialization of the technology of microbially induced calcium carbonate precipitation from lab to field scale. PMID:24194735

Calcifying Cyanobacteria - The potential of biomineralization for Carbon Capture and Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansson, Christer G; Northen, Trent

2010-03-26

Employment of cyanobacteria in biomineralization of carbon dioxide by calcium carbonate precipitation offers novel and self-sustaining strategies for point-source carbon capture and sequestration. Although details of this process remain to be elucidated, a carbon-concentrating mechanism, and chemical reactions in exopolysaccharide or proteinaceous surface layers are assumed to be of crucial importance. Cyanobacteria can utilize solar energy through photosynthesis to convert carbon dioxide to recalcitrant calcium carbonate. Calcium can be derived from sources such as gypsum or industrial brine. A better understanding of the biochemical and genetic mechanisms that carry out and regulate cynaobacterial biomineralization should put us in a positionmore » where we can further optimize these steps by exploiting the powerful techniques of genetic engineering, directed evolution, and biomimetics.« less

Conversion of calcium sulphide to calcium carbonate during the process of recovery of elemental sulphur from gypsum waste.

PubMed

de Beer, M; Maree, J P; Liebenberg, L; Doucet, F J

2014-11-01

The production of elemental sulphur and calcium carbonate (CaCO3) from gypsum waste can be achieved by thermally reducing the waste into calcium sulphide (CaS), which is then subjected to a direct aqueous carbonation step for the generation of hydrogen sulphide (H2S) and CaCO3. H2S can subsequently be converted to elemental sulphur via the commercially available chemical catalytic Claus process. This study investigated the carbonation of CaS by examining both the solution chemistry of the process and the properties of the formed carbonated product. CaS was successfully converted into CaCO3; however, the reaction yielded low-grade carbonate products (i.e. <90 mass% as CaCO3) which comprised a mixture of two CaCO3 polymorphs (calcite and vaterite), as well as trace minerals originating from the starting material. These products could replace the Sappi Enstra CaCO3 (69 mass% CaCO3), a by-product from the paper industry which is used in many full-scale AMD neutralisation plants but is becoming insufficient. The insight gained is now also being used to develop and optimize an indirect aqueous CaS carbonation process for the production of high-grade CaCO3 (i.e. >99 mass% as CaCO3) or precipitated calcium carbonate (PCC). Copyright © 2014 Elsevier Ltd. All rights reserved.

Atmospheric deposition as a source of carbon and nutrients to an alpine catchment of the Colorado Rocky Mountains

NASA Astrophysics Data System (ADS)

Mladenov, N.; Williams, M. W.; Schmidt, S. K.; Cawley, K.

2012-08-01

Many alpine areas are experiencing deglaciation, biogeochemical changes driven by temperature rise, and changes in atmospheric deposition. There is mounting evidence that the water quality of alpine streams may be related to these changes, including rising atmospheric deposition of carbon (C) and nutrients. Given that barren alpine soils can be severely C limited, atmospheric deposition sources may be an important source of C and nutrients for these environments. We evaluated the magnitude of atmospheric deposition of C and nutrients to an alpine site, the Green Lake 4 catchment in the Colorado Rocky Mountains. Using a long-term dataset (2002-2010) of weekly atmospheric wet deposition and snowpack chemistry, we found that volume weighted mean dissolved organic carbon (DOC) concentrations were 1.12 ± 0.19 mg l-1, and weekly concentrations reached peaks as high at 6-10 mg l-1 every summer. Total dissolved nitrogen concentration also peaked in the summer, whereas total dissolved phosphorus and calcium concentrations were highest in the spring. To investigate potential sources of C in atmospheric deposition, we evaluated the chemical quality of dissolved organic matter (DOM) and relationships between DOM and other solutes in wet deposition. Relationships between DOC concentration, fluorescence, and nitrate and sulfate concentrations suggest that pollutants from nearby urban and agricultural sources and organic aerosols derived from sub-alpine vegetation may influence high summer DOC wet deposition concentrations. Interestingly, high DOC concentrations were also recorded during "dust-in-snow" events in the spring, which may reflect an association of DOM with dust. Detailed chemical and spectroscopic analyses conducted for samples collected in 2010 revealed that the DOM in many late spring and summer samples was less aromatic and polydisperse and of lower molecular weight than that of winter and fall samples. Our C budget estimates for the Green Lake 4 catchment illustrated that wet deposition (9.9 kg C ha-1 yr-1) and dry deposition (6.9 kg C ha-1 yr-1) were a combined input of approximately 17 kg C ha-1 yr-1, which could be as high as 24 kg C ha-1 yr-1 in high dust years. This atmospheric C input approached the C input from microbial autotrophic production in barren soils. Atmospheric wet and dry deposition also contributed 4.3 kg N ha-1 yr-1, 0.15 kg P ha-1 yr-1, and 2.7 kg Ca2+ ha-1 yr-1 to this alpine catchment.

Perfusion electrodeposition of calcium phosphate on additive manufactured titanium scaffolds for bone engineering.

PubMed

Chai, Yoke Chin; Truscello, Silvia; Bael, Simon Van; Luyten, Frank P; Vleugels, Jozef; Schrooten, Jan

2011-05-01

A perfusion electrodeposition (P-ELD) system was reported to functionalize additive manufactured Ti6Al4V scaffolds with a calcium phosphate (CaP) coating in a controlled and reproducible manner. The effects and interactions of four main process parameters - current density (I), deposition time (t), flow rate (f) and process temperature (T) - on the properties of the CaP coating were investigated. The results showed a direct relation between the parameters and the deposited CaP mass, with a significant effect for t (P=0.001) and t-f interaction (P=0.019). Computational fluid dynamic analysis showed a relatively low electrolyte velocity within the struts and a high velocity in the open areas within the P-ELD chamber, which were not influenced by a change in f. This is beneficial for promoting a controlled CaP deposition and hydrogen gas removal. Optimization studies showed that a minimum t of 6 h was needed to obtain complete coating of the scaffold regardless of I, and the thickness was increased by increasing I and t. Energy-dispersive X-ray and X-ray diffraction analysis confirmed the deposition of highly crystalline synthetic carbonated hydroxyapatite under all conditions (Ca/P ratio=1.41). High cell viability and cell-material interactions were demonstrated by in vitro culture of human periosteum derived cells on coated scaffolds. This study showed that P-ELD provides a technological tool to functionalize complex scaffold structures with a biocompatible CaP layer that has controlled and reproducible physicochemical properties suitable for bone engineering. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Critical loads of acidity for 90,000 lakes in northern Saskatchewan: A novel approach for mapping regional sensitivity to acidic deposition

NASA Astrophysics Data System (ADS)

Cathcart, H.; Aherne, J.; Jeffries, D. S.; Scott, K. A.

2016-12-01

Atmospheric emissions of sulphur dioxide (SO2) from large point sources are the primary concern for acidic deposition in western Canada, particularly in the Athabasca Oil Sands Region (AOSR) where prevailing winds may potentially carry SO2 over acid-sensitive lakes in northern Saskatchewan. A novel catchment-scale regression kriging approach was used to assess regional sensitivity and critical loads of acidity for the total lake population of northern Saskatchewan (89,947 lakes). Lake catchments were delineated using Thiessen polygons, and surface water chemistry was predicted for sensitivity indicators (calcium, pH, alkalinity, and acid neutralizing capacity). Critical loads were calculated with the steady state water chemistry model using regression-kriged base cations, sulphate, and dissolved organic carbon concentrations modelled from surface water observations (n > 800) and digital landscape-scale characteristics, e.g., climate, soil, vegetation, landcover, and geology maps. A large region (>13,726 km2) of two or more indicators of acid sensitivity (pH < 6 and acid neutralizing capacity, alkalinity, calcium < 50 μeq L-1) and low critical loads < 5 meq m-2 yr-1 were predicted on the Athabasca Basin. Exceedance of critical loads under 2006 modelled total sulphate deposition was predicted for 12% of the lakes (covering an area of 3742 km2), primarily located on the Athabasca Basin, within 100 km of the AOSR. There have been conflicting scientific reports of impacts from atmospheric emissions from the AOSR; the results of this study suggest that catchments in the Athabasca Basin within 100 km of the AOSR have received acidic deposition in excess of their critical loads and many of them may be at risk of ecosystem damage owing to their sensitivity.

The flame photometric determination of calcium in phosphate, carbonate, and silicate rocks

USGS Publications Warehouse

Kramer, H.

1957-01-01

A flame photometric method of determining calcium in phosphate, carbonate, and silicate locks has been developed Aluminum and phosphate interference was overcome by the addition of a large excess of magnesium. The method is rapid and suitable for routine analysis Results obtained are within ?? 2% of the calcium oxide content. ?? 1957.

Process development for production of coal/sorbent agglomerates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, D.M.

1991-01-01

The goal of this work was to develop a process flow diagram to economically produce a clean-burning fuel from fine Illinois coal. To accomplish this, the process of pelletizing fine coal with calcium hydroxide, a sulfur capturing sorbent, was investigated. Carbonation, which is the reaction of calcium hydroxide with carbon dioxide (in the presence of moisture) to produce a bonding matrix of calcium carbonate, was investigated as a method for improving pellet quality and reducing binder costs. Proper moisture level is critical to allow the reaction to occur. If too much moisture is present in a pellet, the pore spacesmore » are filled and carbon dioxide must diffuse through the water to reach the calcium hydroxide and react. This severely slows or stops the reaction. The ideal situation is when there is just enough moisture to coat the calcium hydroxide allowing for the reaction to proceed. The process has been successfully demonstrated on a pilot-scale as a method of hardening iron ore pellets (Imperato, 1966). Two potential combustion options are being considered for the coal/calcium hydroxide pellets: fluidized bed combustors and industrial stoker boilers.« less

Calcium Carbonate Precipitation by Bacillus and Sporosarcina Strains Isolated from Concrete and Analysis of the Bacterial Community of Concrete.

PubMed

Kim, Hyun Jung; Eom, Hyo Jung; Park, Chulwoo; Jung, Jaejoon; Shin, Bora; Kim, Wook; Chung, Namhyun; Choi, In-Geol; Park, Woojun

2016-03-01

Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO2. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery.

Coexistence of three calcium carbonate polymorphs in the shell of the Antarctic clam Laternula elliptica

NASA Astrophysics Data System (ADS)

Nehrke, Gernot; Poigner, Harald; Wilhelms-Dick, Dorothee; Brey, Thomas; Abele, Doris

2012-05-01

We analyzed shell cuts of five individuals of the Antarctic bivalve Laternula elliptica from three locations along the Antarctic Peninsula by means of Confocal Raman Microscopy (CRM) as well as Electron Microprobe (EMP). The shell of L. elliptica has been previously described as being composed of aragonite exclusively. Now, CRM mapping reveals that three polymorphs of calcium carbonate - aragonite, calcite, and vaterite - are present in the chondrophore region of the examined individuals. Annual shell growth layers continue through aragonite and vaterite, suggesting simultaneous mineralization of both polymorphs. Spatially congruent EMP scans showed that the calcium carbonate polymorph affects the distribution of magnesium and strontium within the chondrophore. This is, to our knowledge, the first report of the coexistence of these three calcium carbonate polymorphs within the mineralized structures of a marine calcifying organism. Particularly the presence of vaterite is unexpected, but shows striking similarities to some fish otoliths. The strong effect of the calcium carbonate polymorph on trace element incorporation restrict the suitability of magnesium and strontium based proxies for the chondrophore area of L. elliptica.

Influence of calcium carbonate on extraction yield and quality of extra virgin oil from olive (Olea europaea L. cv. Coratina).

PubMed

Squeo, G; Silletti, R; Summo, C; Paradiso, V M; Pasqualone, A; Caponio, F

2016-10-15

The aim of the research was to evaluate the effect of calcium carbonate (1%, 2%, and 4% of addition) at two different particle sizes (2.7μm and 5.7μm), added at the beginning of the malaxation phase, on both the extraction yield and the quality of oil obtained from Coratina olives at different ripening index. The results showed that calcium carbonate significantly increased the extraction yield of olive oil, more than affecting chemical indices. In particular, for less ripened olives, 1-2% of larger particle size calcium carbonate addiction determined a significant increase of the extraction effectiveness, ranging from 4.0 to 4.9%, while more ripened olives required higher amounts of coadjuvant (2-4% when using the larger particle size and 4% when using the smaller one), with a significant increase of the extraction yield up to 5%. Moreover, an increase of pungent perception was observed in some cases when adding calcium carbonate to more ripened olives. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preeminent productivity of 1,3-propanediol by Clostridium butyricum JKT37 and the role of using calcium carbonate as pH neutraliser in glycerol fermentation.

PubMed

Tee, Zhao Kang; Jahim, Jamaliah Md; Tan, Jian Ping; Kim, Byung Hong

2017-06-01

Calcium carbonate was evaluated as a replacement for the base during the fermentation of glycerol by a highly productive strain of 1,3-propanediol (PDO), viz., Clostridium butyricum JKT37. Due to its high specific growth rate (µ max =0.53h -1 ), 40g/L of glycerol was completely converted into 19.6g/L of PDO in merely 7h of batch fermentation, leaving only acetate and butyrate as the by-products. The accumulation of these volatile fatty acids was circumvented with the addition of calcium carbonate as the pH neutraliser before the fermentation was inoculated. An optimal amount of 15g/L of calcium carbonate was statistically determined from screening with various glycerol concentrations (20-120g/L). By substituting potassium hydroxide with calcium carbonate as the pH neutraliser for fermentation in a bioreactor, a similar yield (Y PDO/glycerol =0.6mol/mol) with a constant pH was achieved at the end of the fermentation. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of fly-ash particulate material and oxide catalysts in stone degradation

NASA Astrophysics Data System (ADS)

Hutchinson, A. J.; Johnson, J. B.; Thompson, G. E.; Wood, G. C.; Sage, P. W.; Cooke, M. J.

Studies of fly-ash composition identified the presence of calcium and sulphur, indicating their potential role as sources of calcium sulphate. Residual acidity (particularly for oil fly ash) suggested the possibility of enhanced chemical reaction, and the presence of transition metals, probably as oxides, might accelerate the oxidation of SO 2 to SO 42-. Exposure tests in a laboratory-based rig simulating dry deposition on Portland and Monks Park limestone, either seeded or unseeded with fly-ash particulate material or transition metal oxide catalysts, were carried out using an SO 2-containing environment at 95% r.h. Enhanced sulphation of these seeded limestones due to the above factors was minimal; at high loadings of fly ash, there was even evidence of masking the limestone surface, reducing sulphation. However, pure CaCO 3 powder in the exposure rig showed increases in sulphation when seeded with metal oxide catalysts. Thus the limestones examined contained sufficient inherent catalysts for the oxidation of SO 2 to SO 42- to proceed at such a rate that external catalysts were superfluous. This implies that dissolution rate of SO 2 in moisture films controls the availability of species for reaction with these carbonate-based stones and that fly ash deposited from the atmosphere does not enhance the reaction.

Increased calcium absorption from synthetic stable amorphous calcium carbonate: double-blind randomized crossover clinical trial in postmenopausal women.

PubMed

Vaisman, Nachum; Shaltiel, Galit; Daniely, Michal; Meiron, Oren E; Shechter, Assaf; Abrams, Steven A; Niv, Eva; Shapira, Yami; Sagi, Amir

2014-10-01

Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (CCC) using the dual stable isotope technique. The study was conducted in the Unit of Clinical Nutrition, Tel Aviv Sourasky Medical Center, Israel. The study population included 15 early postmenopausal women aged 54.9 ± 2.8 (mean ± SD) years with no history of major medical illness or metabolic bone disorder, excess calcium intake, or vitamin D deficiency. Standardized breakfast was followed by randomly provided CCC or ACC capsules containing 192 mg elemental calcium labeled with 44Ca at intervals of at least 3 weeks. After swallowing the capsules, intravenous CaCl2 labeled with 42Ca on was administered on each occasion. Fractional calcium absorption (FCA) of ACC and CCC was calculated from the 24-hour urine collection following calcium administration. The results indicated that FCA of ACC was doubled (± 0.96 SD) on average compared to that of CCC (p < 0.02). The higher absorption of the synthetic stable ACC may serve as a more efficacious way of calcium supplementation. © 2014 American Society for Bone and Mineral Research.

Template-assisted mineral formation via an amorphous liquid phase precursor route

NASA Astrophysics Data System (ADS)

Amos, Fairland F.

The search for alternative routes to synthesize inorganic materials has led to the biomimetic route of producing ceramics. In this method, materials are manufactured at ambient temperatures and in aqueous solutions with soluble additives and insoluble matrix, similar to the biological strategy for the formation of minerals by living organisms. Using this approach, an anionic polypeptide additive was used to induce an amorphous liquid-phase precursor to either calcium carbonate or calcium phosphate. This precursor was then templated on either organic or inorganic substrates. Non-equilibrium morphologies, such as two-dimensional calcium carbonate films, one-dimensional calcium carbonate mesostructures and "molten" calcium phosphate spherulites were produced, which are not typical of the traditional (additive-free) solution grown crystals in the laboratory. In the study of calcium carbonate, the amorphous calcium carbonate mineral formed via the liquid-phase precursor, either underwent a dissolution-recrystallization event or a pseudo-solid-state transformation to produce different morphologies and polymorphs of the mineral. Discrete or aggregate calcite crystals were formed via the dissolution of the amorphous phase to allow the reprecipitation of the stable crystal. Non-equilibrium morphologies, e.g., films, mesotubules and mesowires were templated using organic and inorganic substrates and compartments. These structures were generated via an amorphous solid to crystalline solid transformation. Single crystalline tablets and mesowires of aragonite, which are reported to be found only in nature as skeletal structures of marine organisms, such as mollusk nacre and echinoderm teeth, were successfully synthesized. These biomimetic structures were grown via the polymer-induced liquid-phase precursor route in the presence of magnesium. Only low magnesium-bearing calcite was formed in the absence of the polymer. A similar approach of using a polymeric additive was implemented in calcium phosphate. Spherulitic crystals and films, seemingly formed from a molten state, were produced. These structures served as nucleating surfaces for the radial formation of calcium oxalate minerals. The composite calcium phosphate-calcium oxalate assemblies are similar to the core-shell structures found in certain kidney stones.

Molecular dynamics study of the solvation of calcium carbonate in water.

PubMed

Bruneval, Fabien; Donadio, Davide; Parrinello, Michele

2007-10-25

We performed molecular dynamics simulations of diluted solutions of calcium carbonate in water. To this end, we combined and tested previous polarizable models. The carbonate anion forms long-living hydrogen bonds with water and shows an amphiphilic character, in which the water molecules are expelled in a region close to its C(3) symmetry axis. The calcium cation forms a strongly bound ion pair with the carbonate. The first hydration shell around the CaCO(3) pair is found to be very similar to the location of the water molecules surrounding CaCO(3) in ikaite, the hydrated mineral.

Compressibility and compactibility of granules produced by wet and dry granulation.

PubMed

Bacher, C; Olsen, P M; Bertelsen, P; Sonnergaard, J M

2008-06-24

The bulk properties, compactibility and compressibility of granules produced by wet and dry granulation were compared applying a rotary tablet press, three different morphological forms of calcium carbonate and two particle sizes of sorbitol. Granules from both granulation methods possessed acceptable flow properties; however, the ground (Mikhart) and cubic (Scoralite) calcium carbonate demonstrated better die-filling abilities in the tablet press than the scalenhedral calcium carbonate (Sturcal). The wet processed granules showed in general larger compression properties. This was explained as these granules were mechanical stronger and had a higher initial porosity. In some cases, a large particle surface area of calcium carbonate and sorbitol resulted in a small, insignificant improvement of the consolidation characteristics. A correlation between the compression and compaction characteristics was demonstrated.

Subcellular localization of calcium and Ca-ATPase activity during nuclear maturation in Bufo arenarum oocytes.

PubMed

Ramos, Inés; Cisint, Susana B; Crespo, Claudia A; Medina, Marcela F; Fernández, Silvia N

2009-08-01

The localization of calcium and Ca-ATPase activity in Bufo arenarum oocytes was investigated by ultracytochemical techniques during progesterone-induced nuclear maturation, under in vitro conditions. No Ca2+ deposits were detected in either control oocytes or progesterone-treated ones for 1-2 h. At the time when nuclear migration started, electron dense deposits of Ca2+ were visible in vesicles, endoplasmic reticulum cisternae and in the space between the annulate lamellae membranes. Furthermore, Ca-ATPase activity was also detected in these membrane structures. As maturation progressed, the cation deposits were observed in the cytomembrane structures, which underwent an important reorganization and redistribution. Thus, they moved from the subcortex and became located predominantly in the oocyte cortex area when nuclear maturation ended. Ca2+ stores were observed in vesicles surrounding or between the cortical granules, which are aligned close to the plasma membrane. The positive Ca-ATPase reaction in these membrane structures could indicate that the calcium deposit is an ATP-dependent process. Our results suggest that during oocyte maturation calcium would be stored in membrane structures where it remains available for release at the time of fertilization. Data obtained under our experimental conditions indicate that calcium from the extracellular medium would be important for the oocyte maturation process.

Review of calcium carbonate polymorph precipitation in spring systems

NASA Astrophysics Data System (ADS)

Jones, Brian

2017-05-01

Many spring deposits throughout the world are characterized by spectacular deposits of calcium carbonate that are formed of various combinations of aragonite and calcite, and in very rare cases vaterite. The factors that control the precipitation of the aragonite and calcite have been the subject of considerable debate that has been based on natural precipitates and information gained from numerous laboratory experiments. Synthesis of this information indicates that there is probably no single universal factor that controls calcite and aragonite precipitation in all springs. Instead, the reason for aragonite as opposed to calcite precipitation should be ascertained by considering the following ordered series of possibilities for each system. First, aragonite, commonly with calcite as a co-precipitate, will form from spring water that has a high CO2 content and rapid CO2 degassing, irrespective of the Mg:Ca ratio and scale of precipitation. Second, aragonite can be precipitated from waters that have low levels of CO2 degassing provided that the Mg:Ca ratio is high enough to inhibit calcite precipitation. Third, the presence of biofilms may lead to the simultaneous precipitation of aragonite and calcite (irrespective of CO2 degassing or Mg:Ca ratio) either within the different microdomains that develop in the biofilm or because of diurnal changes in various geochemical parameters associated with the biofilm. Although the precipitation of calcite and aragonite has commonly been linked directly to water temperature, there is no clear evidence for this proposition. It is possible, however, that temperature may be influencing another parameter that plays a more direct role in the precipitation of these CaCO3 polymorphs. Despite the advances that have been made, the factors that ultimately control calcite and aragonite are still open to debate because this long-standing problem has still not been fully resolved.

In vitro evaluation of different heat-treated radio frequency magnetron sputtered calcium phosphate coatings.

PubMed

Yonggang, Yan; Wolke, Joop G C; Yubao, Li; Jansen, John A

2007-06-01

Surface chemical compositions, such as calcium/phosphorus ratio and phase content, have a strong influence on the bioactivity and biocompatibility of calcium phosphate (CaP) coatings as applied on orthopedic and dental implants. Hydroxylapatite (HA) and dicalcium pyrophosphate (DCPP) coatings were prepared on titanium substrates by RF magnetron sputter deposition. The surfaces were left as-prepared (amorphous HA coating; A-HA, amorphous DCPP coating; A-DCPP) or heat treated with: infrared (IR) at 550 degrees C (I-HA) or at 650 degrees C (I-DCPP), and a water steam at 140 degrees C (S-HA and S-DCPP). The surface changes of these coatings were determined after incubation in simulated body fluid (SBF). Also, the growth of rat bone marrow cells (RBM) was studied with scanning electron microscopy (SEM). Both IR and water steam heat treatment changed the sputter-deposited coatings from the amorphous into the crystalline phase. As-prepared amorphous coatings dissolved partially in SBF within 4 weeks of incubation, while heat-treated coatings supported the deposition of a precipitate, i.e., carbonated apatite on both I-HA and S-HA specimens, and tricalciumphosphate on the I-DCPP and S-DCPP specimens. The Ca/P ratio of the A-HA, I-HA, S-HA, A-DCPP, I-DCPP and S-DCPP coatings changed, respectively, from 1.98 to 1.12, 2.01 to 1.76, 1.91 to 1.68, 0.76 to 1.23, 0.76 to 1.26 and 1.62 to 1.55 after 4 weeks of incubation in SBF. Finally, the RBM cells grew well on all heat-treated coatings, but showed different mineralization morphology during cell culturing. The different heat-treatment procedures for the sputtered HA and DCPP coatings influenced the surface characteristics of these coatings, whereby a combination of crystallinity and specific phase composition (Ca/P ratio) strongly affected their in vitro bioactivity.

An early-branching microbialite cyanobacterium forms intracellular carbonates.

PubMed

Couradeau, Estelle; Benzerara, Karim; Gérard, Emmanuelle; Moreira, David; Bernard, Sylvain; Brown, Gordon E; López-García, Purificación

2012-04-27

Cyanobacteria have affected major geochemical cycles (carbon, nitrogen, and oxygen) on Earth for billions of years. In particular, they have played a major role in the formation of calcium carbonates (i.e., calcification), which has been considered to be an extracellular process. We identified a cyanobacterium in modern microbialites in Lake Alchichica (Mexico) that forms intracellular amorphous calcium-magnesium-strontium-barium carbonate inclusions about 270 nanometers in average diameter, revealing an unexplored pathway for calcification. Phylogenetic analyses place this cyanobacterium within the deeply divergent order Gloeobacterales. The chemical composition and structure of the intracellular precipitates suggest some level of cellular control on the biomineralization process. This discovery expands the diversity of organisms capable of forming amorphous calcium carbonates.

Comparison of the Absorption of Calcium Carbonate and Calcium Citrate after Roux-en-Y Gastric Bypass

PubMed Central

Tondapu, P.; Provost, D.; Adams-Huet, B.; Sims, T.; Chang, C.; Sakhaee, K.

2015-01-01

Introduction Roux-en-Y gastric bypass (RYGB) restricts food intake. Consequently, patients consume less calcium. In addition, food no longer passes through the duodenum, the main site of calcium absorption. Therefore, calcium absorption is significantly impaired. The goal of this study is to compare two common calcium supplements in gastric bypass patients. Method Nineteen patients were enrolled in a randomized, double-blinded, crossover study comparing the absorption of calcium from calcium carbonate and calcium citrate salts. Serum and urine calcium levels were assessed for peak values (Cmax) and cumulative calcium increment (area under the curve [AUC]). Serum PTH was assessed for minimum values (PTHmin) and cumulative PTH decrement (AUC). Statistical analysis was performed using a repeated analysis of variance model. Results Eighteen subjects completed the study. Calcium citrate resulted in a significantly higher serum Cmax (9.4+0.4 mg/dl vs. 9.2+0.3 mg/dl, p=0.02) and serum AUC (55+2 mg/dl vs. 54+2 mg/dl, p=0.02). Calcium citrate resulted in a significantly lower PTHmin (24+11 pg/ml vs. 30+13 pg/ml, p=0.01) and a higher AUC (−32+51 pg/ml vs. −3+56 pg/ml, p=0.04). There was a non-significant trend for higher urinary AUC in the calcium citrate group (76.13+36.39 mg/6 h vs. 66.04+40.82, p=0.17). Conclusion Calcium citrate has superior bioavailability than calcium carbonate in RYGB patients. PMID:19437082

Calcium carbonate overdose

MedlinePlus

Calcium carbonate is not very poisonous. Recovery is quite likely. But, long-term overuse is more serious than a single overdose, because it can cause kidney damage. Few people die from an antacid overdose. Keep ...

[Comparison of the therapeutic effect on skeletal fluorosis and impact on urine fluoride value among fire needle therapy, electroacupuncture and calcium carbonate D3].

PubMed

Wang, Tong; Yang, Xu-Guang; Wu, Zhong-Chao; Zhou, Jin-Cao; Chen, Zhong-Jie; Hu, Jing; Jiao, Yue; Zhao, Xiao-Guang

2014-03-01

To observe the impacts on skeletal fluorosis pain, joint motor dysfunction and urine fluoride excretion in the treatment with fire needle therapy, electroacupuncture and calcium carbonate D3. The randomized controlled trial was adopted. Ninety-five patients were randomized into a fire needle group (31 cases), an electroacupuncture group (33 cases) and a calcium carbonate D3 group (31 cases). In the fire needle group and the electroacupuncture group, Ashi points, Dazhui (GV 14), Geshu (BL 17), Quchi (LI 11), Hegu (LI 4), Xuehai (SP 10) points were selected and stimulated with fire needle and electroacupuncture separately, three times a week. In the calcium carbonate D3 group, calcium carbonate D3 tablets was prescribed for oral administration, 600 mg each time, twice a day. The duration of treatment was 2 months in the electroacupuncture group and calcium carbonate D3 group and 1 month in the fire needle group. VAS score, the range of motion (ROM) and urine fluoride value were compared before and after treatment in the patients of the three groups. After treatment, VAS value and ROM were improved significantly in the patients of the three groups (all P < 0.05), the difference was not significant in comparison of the three groups (all P > 0.05). After treatment, the urine fluoride value was increased significantly in the fire needle group [(7.89 +/- 3.61) mg/L vs (9.81 +/- 4.17) mg/L, P < 0.01] and was increased in the electroacupuncture group [(7.53 +/- 3.46) mg/L vs (8.97 +/- 4.21) mg/L, P < 0.05]. The difference was not significant in comparison before and after treatment in the calcium carbonate D3 group (P > 0.05). The fire needle therapy, electroacupuncture and calcium carbonate D3 all have the clinical value in the prevention and treatment of skeletal fluorosis and the difference in the therapeutic effect has not been discovered among them yet at present. But it has been found that the fire needle therapy and electroacupuncture display the active significance in the promotion of urine fluoride excretion.

Hydrogeochemical signatures of catchment evolution - the role of calcium and sulphate release in the constructed Hühnerwasser ("Chicken Creek") catchment

NASA Astrophysics Data System (ADS)

Pohle, Ina; Hu, Yuzhu; Schaaf, Wolfgang; Gerwin, Werner; Hinz, Christoph

2016-04-01

The constructed Hühnerwasser ("Chicken Creek") catchment is an ecohydrological system in an initial state of development. The catchment with an area of 6 ha was built up from quaternary sediments in the post-mining landscape of Lusatia in Eastern Germany and serves as a critical zone observatory for detecting ecosystem transition. The soil substrate is characterized as sands to loamy sands with low carbonate contents but significant amounts of gypsum in the sediments of the catchment. The catchment undergoes a strong transition from an abiotic system in the initial years to a system with growing influence of biota. Concerning the hydrology, a regime shift from surface runoff to groundwater flow dominated processes is significant. It is of interest, whether the catchment transition is also reflected by hydrogeochemical indicators. We assume gypsum dissolution as dominant process at the catchment scale. In order to investigate the hydrogeochemical evolution of the catchment we analysed electric conductivity, calcium and sulphate concentrations and pH-values of biweekly composite samples from 2007-2013 of the atmospheric deposition, of runoff and soil water. The two observation points in the flowing water represent surface runoff and groundwater discharge respectively. Soil water has been analysed at four soil pits in three depths. The monitoring data were provided by the Research Platform Chicken Creek (https://www.tu-cottbus.de/projekte/en/oekosysteme/startseite.html). From the macroscopic data analysis we found an exponential decay of the electric conductivity, calcium and sulphate concentrations in the flowing waters and some of the soil pits. In the flowing water, the decrease slope of the electric conductivity and the calcium and sulphate concentrations is almost identical. The calcium / sulphate molar ratio as an indicator of gypsum dissolution is almost equal to one up to 2010, afterwards more calcium than sulphate is released. The pH-values in the flowing and soil water are generally higher than in the atmospheric deposition, they do show variabilites but no trend behaviour. The time series analyses showed that the interannual variability of the hydrogeochemical properties is less pronounced in the first years of ecosystem development than in the later years. This leads to the conclusion, that in the first years, gypsum dissolution is the major source for calcium and sulphate in the soil and the flowing waters. The increasing interannual variability and changes in the calcium / sulphate ratio in the later years might be interpreted as hydrogeochemical response to the development of vegetation and acidification due to the development of the rhizosphere.

Restoration of parathyroid function after change of phosphate binder from calcium carbonate to lanthanum carbonate in hemodialysis patients with suppressed serum parathyroid hormone.

PubMed

Inaba, Masaaki; Okuno, Senji; Nagayama, Harumi; Yamada, Shinsuke; Ishimura, Eiji; Imanishi, Yasuo; Shoji, Shigeichi

2015-03-01

Control of phosphate is the most critical in the treatment of chronic kidney disease with mineral and bone disorder (CKD-MBD). Because calcium-containing phosphate binder to CKD patients is known to induce adynamic bone disease with ectopic calcification by increasing calcium load, we examined the effect of lanthanum carbonate (LaC), a non-calcium containing phosphate binder, to restore bone turnover in 27 hemodialysis patients with suppressed parathyroid function (serum intact parathyroid hormone [iPTH] ≦ 150 pg/mL). At the initiation of LaC administration, the dose of calcium-containing phosphate binder calcium carbonate (CaC) was withdrawn or reduced based on serum phosphate. After initiation of LaC administration, serum calcium and phosphate decreased significantly by 4 weeks, whereas whole PTH and iPTH increased. A significant and positive correlation between decreases of serum calcium, but not phosphate, with increases of whole PTH and iPTH, suggested that the decline in serum calcium with reduction of calcium load by LaC might increase parathyroid function. Serum bone resorption markers, such as serum tartrate-resistant acid phosphatase 5b, and N-telopeptide of type I collagen increased significantly by 4 weeks after LaC administration, which was followed by increases of serum bone formation markers including serum bone alkaline phosphatase, intact procollagen N-propeptide, and osteocalcin. Therefore, it was suggested that LaC attenuated CaC-induced suppression of parathyroid function and bone turnover by decreasing calcium load. In conclusion, replacement of CaC with LaC, either partially or totally, could increase parathyroid function and resultant bone turnover in hemodialysis patients with serum iPTH ≦ 150 pg/mL. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

The Role of Calcium in Ameliorating the Oxidative Stress of Fluoride in Rats.

PubMed

Mohamed, N E

2016-03-01

The present study was carried out to investigate the effects of fluoride toxicity on some biochemical, hormonal, and histological parameters of female rats and the protective role of calcium against such effects. Adult female albino rats were divided into five groups; control group received distilled water for 60 days, calcium group received calcium carbonate with dose of 50 mg/kg three times per week for 60 days, fluoride group received sodium fluoride with dose of 20 mg/kg three times per week for 60 days, calcium + fluoride group received calcium carbonate (50 mg/kg) then after 2 h received sodium fluoride (20 mg/kg) three times per week for 60 days, and fluoride + calcium group received sodium fluoride (20 mg/kg) three times per week for 30 days then received calcium carbonate (50 mg/kg) three times per week for another 30 days. The results showed that the levels of thiobarbituric acid reactive substances, urea, creatinine, alkaline phosphatase, triiodothyronine, thyroxine, parathormone, phosphorous, magnesium, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and gamma glutamyl transferase were significantly increased in rats treated with fluoride while serum estradiol, calcium, and organ glutathione were significantly decreased. The histological examination of the femur bone revealed that fluoride treatment induced thinning of bone trabeculae with wilding of marrow space, demineralization, and loss of trabeculae interconnections. Also, the histological examination of hepatic and renal tissues of fluoride-treated rats showed some damages in these tissues while administration of calcium carbonate for 30 or 60 days during fluoride treatment minimized such damages. It could be concluded that administration of calcium to female rats can ameliorate the hazardous effects of fluoride observed in the biochemical, hormonal, and histological parameters.

Understanding the spatial formation and accumulation of fats, oils and grease deposits in the sewer collection system.

PubMed

Dominic, Christopher Cyril Sandeep; Szakasits, Megan; Dean, Lisa O; Ducoste, Joel J

2013-01-01

Sanitary sewer overflows are caused by the accumulation of insoluble calcium salts of fatty acids, which are formed by the reaction between fats, oils and grease (FOG) and calcium found in wastewaters. Different sewer structural configurations (i.e., manholes, pipes, wet wells), which vary spatially, along with other obstructions (roots intrusion) and pipe deformations (pipe sags), may influence the detrimental buildup of FOG deposits. The purpose of this study was to quantify the spatial variation in FOG deposit formation and accumulation in a pilot-scale sewer collection system. The pilot system contained straight pipes, manholes, roots intrusion, and a pipe sag. Calcium and oil were injected into the system and operated at alkaline (pH = 10) and neutral (pH = 7) pH conditions. Results showed that solid accumulations were slightly higher at neutral pH. Fourier transform infrared (FTIR) analysis on the solids samples confirmed that the solids were indeed calcium-based fatty acid salts. However, the fatty acid profiles of the solids deviated from the profile found from FOG deposits in sewer systems, which were primarily saturated fatty acids. These results confirm the work done previously by researchers and suggest an alternative fate of unsaturated fatty acids that does not lead to their incorporation in FOG deposits in full-scale sewer systems.

Influence of fat and oil type on the yield, physico-chemical properties, and microstructure of fat, oil, and grease (FOG) deposits.

PubMed

Del Mundo, Dann Marie N; Sutheerawattananonda, Manote

2017-11-01

Fat, oil, and grease (FOG) deposit, in the form of calcium soap, was found to cause sanitary sewer overflows due to its adhesion on pipe walls. To address this problem, laboratory-prepared calcium soaps have been used to investigate the formation mechanisms of FOG deposits. However, the fats and oils previously utilized were limited and some soap characteristics were not examined. This research attempted to probe through the properties of calcium soaps prepared from calcium chloride and the fats and oils of chicken, pork, palm olein, soybean, olive, and coconut to further understand FOG formation and stability. Results revealed that FOG deposits may occur as smooth, paste-like material or coarse, semi-solid substance depending on their exposure to excess fat/oil and calcium. The smooth soaps with more excess fat/oil demonstrated high apparent viscosity and consistency index, while the coarse soaps with large levels of calcium signified higher melting endset. Moreover, a soap microstructure showing evident networks and lesser void area displayed higher heat and rheological stability, respectively. Overall, fats and oils with higher oleic to palmitic acid ratio such as palm olein oil, olive oil, chicken fat, and pork fat produced soaps with greater yield and degree of saponification. Hence, establishments and authorities should be alert in managing and monitoring these wastes. On the other hand, soybean oil high in linoleic acid and coconut oil high in lauric acid do not pose an immediate threat to the sewer system since they only produced soaps in small quantity. However, their soaps showed high melting endset which could pose a serious effect when accumulated at large amount. On the whole, the fatty acid profile of fats and oils, the presence of excess fat/oil, and calcium content mainly dictate the appearance, melting, rheology, and microstructure of calcium soaps. Their distinct properties can be used as criteria in predicting the condition and stability of FOG deposits. Copyright © 2017 Elsevier Ltd. All rights reserved.

Differential pulse adsorptive stripping voltammetric determination of nanomolar levels of atorvastatin calcium in pharmaceutical and biological samples using a vertically aligned carbon nanotube/graphene oxide electrode.

PubMed

Silva, Tiago Almeida; Zanin, Hudson; Vicentini, Fernando Campanhã; Corat, Evaldo José; Fatibello-Filho, Orlando

2014-06-07

A novel vertically aligned carbon nanotube/graphene oxide (VACNT-GO) electrode is proposed, and its ability to determine atorvastatin calcium (ATOR) in pharmaceutical and biological samples by differential pulse adsorptive stripping voltammetry (DPAdSV) is evaluated. VACNT films were prepared on a Ti substrate by a microwave plasma chemical vapour deposition method and then treated with oxygen plasma to produce the VACNT-GO electrode. The oxygen plasma treatment exfoliates the carbon nanotube tips exposing graphene foils and inserting oxygen functional groups, these effects improved the VACNT wettability (super-hydrophobic) which is crucial for its electrochemical application. The electrochemical behaviour of ATOR on the VACNT-GO electrode was studied by cyclic voltammetry, which showed that it underwent an irreversible oxidation process at a potential of +1.08 V in pHcond 2.0 (0.2 mol L(-1) buffer phosphate solution). By applying DPAdSV under optimized experimental conditions the analytical curve was found to be linear in the ATOR concentration range of 90 to 3.81 × 10(3) nmol L(-1) with a limit of detection of 9.4 nmol L(-1). The proposed DPAdSV method was successfully applied in the determination of ATOR in pharmaceutical and biological samples, and the results were in close agreement with those obtained by a comparative spectrophotometric method at a confidence level of 95%.

Ubiquitylation Functions in the Calcium Carbonate Biomineralization in the Extracellular Matrix

PubMed Central

Fang, Dong; Pan, Cong; Lin, Huijuan; Lin, Ya; Xu, Guangrui; Zhang, Guiyou; Wang, Hongzhong; Xie, Liping; Zhang, Rongqing

2012-01-01

Mollusks shell formation is mediated by matrix proteins and many of these proteins have been identified and characterized. However, the mechanisms of protein control remain unknown. Here, we report the ubiquitylation of matrix proteins in the prismatic layer of the pearl oyster, Pinctada fucata. The presence of ubiquitylated proteins in the prismatic layer of the shell was detected with a combination of western blot and immunogold assays. The coupled ubiquitins were separated and identified by Edman degradation and liquid chromatography/mass spectrometry (LC/MS). Antibody injection in vivo resulted in large amounts of calcium carbonate randomly accumulating on the surface of the nacreous layer. These ubiquitylated proteins could bind to specific faces of calcite and aragonite, which are the two main mineral components of the shell. In the in vitro calcium carbonate crystallization assay, they could reduce the rate of calcium carbonate precipitation and induce the calcite formation. Furthermore, when the attached ubiquitins were removed, the functions of the EDTA-soluble matrix of the prismatic layer were changed. Their potency to inhibit precipitation of calcium carbonate was decreased and their influence on the morphology of calcium carbonate crystals was changed. Taken together, ubiquitylation is involved in shell formation. Although the ubiquitylation is supposed to be involved in every aspect of biophysical processes, our work connected the biomineralization-related proteins and the ubiquitylation mechanism in the extracellular matrix for the first time. This would promote our understanding of the shell biomineralization and the ubiquitylation processes. PMID:22558208

Mineralization of gellan gum hydrogels with calcium and magnesium carbonates by alternate soaking in solutions of calcium/magnesium and carbonate ion solutions.

PubMed

Lopez-Heredia, Marco A; Łapa, Agata; Reczyńska, Katarzyna; Pietryga, Krzysztof; Balcaen, Lieve; Mendes, Ana C; Schaubroeck, David; Van Der Voort, Pascal; Dokupil, Agnieszka; Plis, Agnieszka; Stevens, Chris V; Parakhonskiy, Bogdan V; Samal, Sangram Keshari; Vanhaecke, Frank; Chai, Feng; Chronakis, Ioannis S; Blanchemain, Nicolas; Pamuła, Elżbieta; Skirtach, Andre G; Douglas, Timothy E L

2018-04-27

Mineralization of hydrogels is desirable prior to applications in bone regeneration. CaCO 3 is a widely used bone regeneration material and Mg, when used as a component of calcium phosphate biomaterials, has promoted bone-forming cell adhesion and proliferation and bone regeneration. In this study, gellan gum (GG) hydrogels were mineralized with carbonates containing different amounts of calcium (Ca) and magnesium (Mg) by alternate soaking in, firstly, a calcium and/or magnesium ion solution and, secondly, a carbonate ion solution. This alternate soaking cycle was repeated five times. Five different calcium and/or magnesium ion solutions, containing different molar ratios of Ca to Mg ranging from Mg-free to Ca-free were compared. Carbonate mineral formed in all sample groups subjected to the Ca:Mg elemental ratio in the carbonate mineral formed was higher than in the respective mineralizing solution. Mineral formed in the absence of Mg was predominantly CaCO 3 in the form of a mixture of calcite and vaterite. Increasing the Mg content in the mineral formed led to the formation of magnesian calcite, decreased the total amount of the mineral formed and its crystallinity. Hydrogel mineralization and increasing Mg content in mineral formed did not obviously improve proliferation of MC3T3-E1 osteoblast-like cells or differentiation after 7 days. This article is protected by copyright. All rights reserved.

Postoperative diffuse opacification of a hydrophilic acrylic intraocular lens: analysis of an explant.

PubMed

Cavallini, Gian Maria; Volante, Veronica; Campi, Luca; De Maria, Michele; Fornasari, Elisa; Urso, Giancarlo

2017-06-14

We describe the clinicopathological and ultrastructural features of an opaque single-piece hydrophilic acrylic intraocular lens (IOL) explanted from a patient. The main outcome of this report is the documentation of calcium deposits confirmed by surface analysis. The decrease in visual acuity was due to the opacification of the IOL. The opacification involved both the optic plate and the haptics. The analysis at the scansion electron microscope revealed that the opacity was caused by the deposition of calcium and phosphate within the lens optic and haptics. This is the first case about the opacification of an Oculentis L-313. The opacification was characterized by calcium and phosphate deposition probably due to a morphological alteration of the posterior surface of the IOL.

Calcium isotope evidence for suppression of carbonate dissolution in carbonate-bearing organic-rich sediments

NASA Astrophysics Data System (ADS)

Turchyn, Alexandra V.; DePaolo, Donald J.

2011-11-01

Pore fluid calcium isotope, calcium concentration and strontium concentration data are used to measure the rates of diagenetic dissolution and precipitation of calcite in deep-sea sediments containing abundant clay and organic material. This type of study of deep-sea sediment diagenesis provides unique information about the ultra-slow chemical reactions that occur in natural marine sediments that affect global geochemical cycles and the preservation of paleo-environmental information in carbonate fossils. For this study, calcium isotope ratios (δ 44/40Ca) of pore fluid calcium from Ocean Drilling Program (ODP) Sites 984 (North Atlantic) and 1082 (off the coast of West Africa) were measured to augment available pore fluid measurements of calcium and strontium concentration. Both study sites have high sedimentation rates and support quantitative sulfate reduction, methanogenesis and anaerobic methane oxidation. The pattern of change of δ 44/40Ca of pore fluid calcium versus depth at Sites 984 and 1082 differs markedly from that of previously studied deep-sea Sites like 590B and 807, which are composed of nearly pure carbonate sediment. In the 984 and 1082 pore fluids, δ 44/40Ca remains elevated near seawater values deep in the sediments, rather than shifting rapidly toward the δ 44/40Ca of carbonate solids. This observation indicates that the rate of calcite dissolution is far lower than at previously studied carbonate-rich sites. The data are fit using a numerical model, as well as more approximate analytical models, to estimate the rates of carbonate dissolution and precipitation and the relationship of these rates to the abundance of clay and organic material. Our models give mutually consistent results and indicate that calcite dissolution rates at Sites 984 and 1082 are roughly two orders of magnitude lower than at previously studied carbonate-rich sites, and the rate correlates with the abundance of clay. Our calculated rates are conservative for these sites (the actual rates could be significantly slower) because other processes that impact the calcium isotope composition of sedimentary pore fluid have not been included. The results provide direct geochemical evidence for the anecdotal observation that the best-preserved carbonate fossils are often found in clay or organic-rich sedimentary horizons. The results also suggest that the presence of clay minerals has a strong passivating effect on the surfaces of biogenic carbonate minerals, slowing dissolution dramatically even in relation to the already-slow rates typical of carbonate-rich sediments.

Evidence for the involvement of carbonic anhydrase and urease in calcium carbonate formation in the gravity-sensing organ of Aplysia californica

NASA Technical Reports Server (NTRS)

Pedrozo, H. A.; Schwartz, Z.; Dean, D. D.; Harrison, J. L.; Campbell, J. W.; Wiederhold, M. L.; Boyan, B. D.

1997-01-01

To better understand the mechanisms that could modulate the formation of otoconia, calcium carbonate granules in the inner ear of vertebrate species, we examined statoconia formation in the gravity-sensing organ, the statocyst, of the gastropod mollusk Aplysia californica using an in vitro organ culture model. We determined the type of calcium carbonate present in the statoconia and investigated the role of carbonic anhydrase (CA) and urease in regulating statocyst pH as well as the role of protein synthesis and urease in statoconia production and homeostasis in vitro. The type of mineral present in statoconia was found to be aragonitic calcium carbonate. When the CA inhibitor, acetazolamide (AZ), was added to cultures of statocysts, the pH initially (30 min) increased and then decreased. The urease inhibitor, acetohydroxamic acid (AHA), decreased statocyst pH. Simultaneous addition of AZ and AHA caused a decrease in pH. Inhibition of urease activity also reduced total statoconia number, but had no effect on statoconia volume. Inhibition of protein synthesis reduced statoconia production and increased statoconia volume. In a previous study, inhibition of CA was shown to decrease statoconia production. Taken together, these data show that urease and CA play a role in regulating statocyst pH and the formation and maintenance of statoconia. CA produces carbonate ion for calcium carbonate formation and urease neutralizes the acid formed due to CA action, by production of ammonia.

Soil stabilization by a prokaryotic desert crust - Implications for Precambrian land biota

NASA Technical Reports Server (NTRS)

Campbell, S. E.

1979-01-01

The ecology of the cyanophyte-dominated stromatolitic mat forming the ground cover over desert areas of Utah and Colorado is investigated and implications for the formation of mature Precambrian soils are discussed. The activation of the growth of the two species of filamentous cyanophyte identified and the mobility of their multiple trichromes upon wetting are observed, accompanied by the production and deposition of a sheath capable of accreting and stabilizing sand and clay particles. The formation of calcium carbonate precipitates upon the repeated wetting and drying of desert crust is noted, and it is suggested that the desert crust community may appear in fossil calcrete deposits as lithified microscopic tubes and cellular remains of algal trichromes. The invasion of dry land by both marine and freshwater algae on the model of the desert crust is proposed to be responsible for the accumulation, stabilization and biogenic modification of mature Precambrian soils.

Consequences of calcium decline on the embryogenesis and life history of Daphnia magna.

PubMed

Giardini, Jamie-Lee; Yan, Norman D; Heyland, Andreas

2015-07-01

Ambient calcium is declining in thousands of soft-water lake habitats in temperate regions as a consequence of unsustainable forestry practices, decreased atmospheric calcium deposition and acidic deposition. As their exoskeleton is heavily reinforced with calcium, freshwater crustaceans have a high specific calcium requirement relative to other aquatic organisms. Daphnia, in particular, is an ideal crustacean for investigating the consequences of calcium decline because it is an abundant and important member of freshwater zooplankton communities. Although it has been established that adult and juvenile Daphnia have different tolerances to low ambient calcium as a result of their different life stage-specific calcium requirements, the consequences of declining calcium on embryonic development have never been investigated. Here, we describe the distribution of calcium in embryonic stages of D. magna and introduce a novel and easy to use staging scheme. We tested whether calcium can be traced from mothers to their offspring. Finally, we assessed the fitness consequences of maternal provisioning in limiting calcium environments. We found that while embryos require calcium for their development and moulting, they do not equilibrate with environmental calcium levels. Instead, we were able to trace calcium from mothers to their offspring. Furthermore, our data strongly suggest that females are faced with an allocation trade-off between providing calcium to their offspring and using it for growth and moulting. Together, these data provide novel insights into the consequences of calcium decline for freshwater zooplankton. © 2015. Published by The Company of Biologists Ltd.

Post-GOE redox insights from Mo isotopes, Ce anomalies, and Mn from the 2.24 Ga Kazput Formation

NASA Astrophysics Data System (ADS)

Thoby, M.; Konhauser, K.; Philippot, P.; Killingsworth, B.; Warchola, T.; Lalonde, S.

2017-12-01

Following the Great Oxidation event (GOE) defined from 2.45 to 2.2 Ga, an event marking the first appearance of widespread atmospheric oxygen, a combination of decreased Mn(II) supply from land and increased Mn(IV)-precipitation in the oceans should have resulted in lower concentrations of Mn in seawater. Nevertheless, it appears that some early Proterozoic marine sediments record high seawater Mn concentrations hundreds of millions of years after the GOE. Here we investigate a Mn excursion associated with marine carbonates and shales of the 2.31 Ga Kazput Formation. Samples were recovered from drill core collected during the Turee Creek Drilling Project (TCDP). Using molybdenum (Mo) isotope data coupled with cerium (Ce) anomalies, we define the redox condition of the Kazput depositional environment. Initial results show no Mo fractionation and few cerium anomalies in carbonates, pointing to an anoxic basin without Mn oxide precipitates. Additionally, XRF data on the shales indicates an association of Mn with calcium (Ca) suggesting an anoxic environment at the time of their deposition. Our results provide new insights into the nature and environment of the Turee Creek basin and the extent of oxygenation of surface waters after the GOE.

pH-controlled drug loading and release from biodegradable microcapsules.

PubMed

Zhao, Qinghe; Li, Bingyun

2008-12-01

Microcapsules made of biopolymers are of both scientific and technological interest and have many potential applications in medicine, including their use as controlled drug delivery devices. The present study makes use of the electrostatic interaction between polycations and polyanions to form a multilayered microcapsule shell and also to control the loading and release of charged drug molecules inside the microcapsule. Micron-sized calcium carbonate (CaCO3) particles were synthesized and integrated with chondroitin sulfate (CS) through a reaction between sodium carbonate and calcium nitrate tetrahydrate solutions suspended with CS macromolecules. Oppositely charged biopolymers were alternately deposited onto the synthesized particles using electrostatic layer-by-layer self-assembly, and glutaraldehyde was introduced to cross-link the multilayered shell structure. Microcapsules integrated with CS inside the multilayered shells were obtained after decomposition of the CaCO3 templates. The integration of a matrix (i.e., CS) permitted the subsequent selective control of drug loading and release. The CS-integrated microcapsules were loaded with a model drug, bovine serum albumin labeled with fluorescein isothiocyanate (FITC-BSA), and it was shown that pH was an effective means of controlling the loading and release of FITC-BSA. Such CS-integrated microcapsules may be used for controlled localized drug delivery as biodegradable devices, which have advantages in reducing systemic side effects and increasing drug efficacy.

Application of Bacillus subtilis 168 as a multifunctional agent for improvement of the durability of cement mortar.

PubMed

Park, Sung-Jin; Park, Jong-Myong; Kim, Wha-Jung; Ghim, Sa-Youl

2012-11-01

Microbiological calcium carbonate precipitation (MCCP) has been investigated for its ability to improve the durability of cement mortar. However, very few strains have been applied to crack remediation and strengthening of cementitious materials. In this study, we report the biodeposition of Bacillus subtilis 168 and its ability to enhance the durability of cement material. B. subtilis 168 was applied to the surface of cement specimens. The results showed a new layer of deposited organic-inorganic composites on the surface of the cement paste. In addition, the water permeability of the cement paste treated with B. subtilis 168 was lower than that of non-treated specimens. Furthermore, artificial cracks in the cement paste were completely remediated by the biodeposition of B. subtilis 168. The compressive strength of cement mortar treated with B. subtilis 168 increased by about 19.5% when compared with samples completed with only B4 medium. Taken together, these findings suggest that the biodeposition of B. subtilis 168 could be used as a sealing and coating agent to improve the strength and water resistance of concrete. This is the first paper to report the application of Bacillus subtilis 168 for its ability to improve the durability of cement mortar through calcium carbonate precipitation.

Pedogenic replacement of aluminosilicate grains by CaCO3 in Ustollic Haplargids, south-central Montana, U.S.A.

USGS Publications Warehouse

Reheis, M.C.

1988-01-01

A chronosequence of calcic soils formed on granitic glaciofluvial terrace deposits of Rock Creek and the Clarks Fork in south-central Montana shows progressive replacement of aluminosilicate parent-material grains by calcium-magnesium carbonate. The terraces range from late Pliocene to Holocene in age as dated by tephrochronology, correlation, and stream incision rates. Replacement is first seen in soils that are as old as 120,000 yr; the amount and degree of replacement increase in soils older than 120,000 yr along with the development of calcic horizons. Under the petrographic microscope, carbonate replacement of quartz, feldspars, and the groundmass of andesite grains in Rock Creek soils is shown by embayed grains, networks of carbonate along cracks and between parts of polycrystalline grains and optically aligned grain fragments within carbonate masses. Microprobe data suggest that silica is released by replacement because it is absent from carbonate-filled spaces and is depleted in corrosion pits. Little microscopic evidence exists to support displacement of framework grains by carbonate because fragments of a single grain are rarely rotated out of optical alignment. In the calcic soils of Rock Creek, K-fabric (grains floating in a carbonate matrix) may form by both replacement and displacement. ?? 1988.

Calcium and 1,25-dihydroxyvitamin D3 modulate genes of immune and inflammatory pathways in the human colon: a human crossover trial.

PubMed

Protiva, Petr; Pendyala, Swaroop; Nelson, Celeste; Augenlicht, Leonard H; Lipkin, Martin; Holt, Peter R

2016-05-01

A high dietary calcium intake with adequate vitamin D status has been linked to lower colorectal cancer risk, but the mechanisms of these effects are poorly understood. The objective of this study was to elucidate the effects of a Western-style diet (WD) and supplemental calcium and/or 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on the colorectal mucosa. We conducted 2 crossover trials to define molecular pathways in the human colorectum altered by 1) a 4-wk WD supplemented with and without 2 g calcium carbonate/d and 2) a 4-wk WD supplemented with 1,25(OH)2D3 (0.5 μg/d) with or without 2 g calcium carbonate/d. The primary study endpoint was genome-wide gene expression in biopsy specimens of the rectosigmoid colonic mucosa. Serum and urinary calcium concentrations were also measured. Changes in urinary calcium accurately reflected calcium consumption. The WD induced modest upregulation of genes involved in inflammatory pathways, including interferon signaling, and calcium supplementation reversed these toward baseline. In contrast, supplementation of the WD with 1,25(OH)2D3 induced striking upregulation of genes involved in inflammation, immune response, extracellular matrix, and cell adhesion. Calcium supplementation largely abrogated these changes. Supplementing 1,25(OH)2D3 to a WD markedly upregulated genes in immune response and inflammation pathways, which were largely reversed by calcium supplementation. This study provides clinical trial evidence of global gene expression changes occurring in the human colorectum in response to calcium and 1,25(OH)2D3 intervention. One action of 1,25(OH)2D3 is to upregulate adaptive immunity. Calcium appears to modulate this effect, pointing to its biological interaction in the mucosa. This trial was registered at clinicaltrials.gov as NCT00298545 Trial protocol is available at http://clinicalstudies.rucares.org (protocol numbers PHO475 and PHO554). © 2016 American Society for Nutrition.

Enzymatic, urease-mediated mineralization of gellan gum hydrogel with calcium carbonate, magnesium-enriched calcium carbonate and magnesium carbonate for bone regeneration applications.

PubMed

Douglas, Timothy E L; Łapa, Agata; Samal, Sangram Keshari; Declercq, Heidi A; Schaubroeck, David; Mendes, Ana C; der Voort, Pascal Van; Dokupil, Agnieszka; Plis, Agnieszka; De Schamphelaere, Karel; Chronakis, Ioannis S; Pamuła, Elżbieta; Skirtach, Andre G

2017-12-01

Mineralization of hydrogel biomaterials is considered desirable to improve their suitability as materials for bone regeneration. Calcium carbonate (CaCO 3 ) has been successfully applied as a bone regeneration material, but hydrogel-CaCO 3 composites have received less attention. Magnesium (Mg) has been used as a component of calcium phosphate biomaterials to stimulate bone-forming cell adhesion and proliferation and bone regeneration in vivo, but its effect as a component of carbonate-based biomaterials remains uninvestigated. In the present study, gellan gum (GG) hydrogels were mineralized enzymatically with CaCO 3 , Mg-enriched CaCO 3 and magnesium carbonate to generate composite biomaterials for bone regeneration. Hydrogels loaded with the enzyme urease were mineralized by incubation in mineralization media containing urea and different ratios of calcium and magnesium ions. Increasing the magnesium concentration decreased mineral crystallinity. At low magnesium concentrations calcite was formed, while at higher concentrations magnesian calcite was formed. Hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 .4H 2 O) formed at high magnesium concentration in the absence of calcium. The amount of mineral formed and compressive strength decreased with increasing magnesium concentration in the mineralization medium. The calcium:magnesium elemental ratio in the mineral formed was higher than in the respective mineralization media. Mineralization of hydrogels with calcite or magnesian calcite promoted adhesion and growth of osteoblast-like cells. Hydrogels mineralized with hydromagnesite displayed higher cytotoxicity. In conclusion, enzymatic mineralization of GG hydrogels with CaCO 3 in the form of calcite successfully reinforced hydrogels and promoted osteoblast-like cell adhesion and growth, but magnesium enrichment had no definitive positive effect. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Influence of polarized PZT on the crystal growth of calcium phosphate

NASA Astrophysics Data System (ADS)

Sun, Xiaodan; Ma, Chunlai; Wang, Yude; Li, Hengde

2002-01-01

The effects of polarization on the crystallization of calcium phosphate are studied in this work. Crystals of calcium phosphate from saturated solution of hydroxyapatite (HA, Ca 10(PO 4) 6(OH) 2) were deposited on the surfaces of ferroelectric ceramics lead zirconate titanium (Pb(Ti,Zr)O 3, PZT). The results of the experiment demonstrated the acceleration effects of polarized PZT on the crystal growth of calcium phosphate. Furthermore, it is indicated that polarization also influenced the orientation of the deposited crystals due to the growth of a layer of (0 0 2) oriented octacalcium phosphate (OCP, Ca 8H 2(PO 4) 6·5H 2O) on the negatively charged surfaces of PZT.

Preliminary investigation of the elemental variation and diagenesis of a tabular uranium deposit, La Sal Mine, San Juan County, Utah

USGS Publications Warehouse

Brooks, Robert A.; Campbell, John A.

1976-01-01

Ore in the La Sal mine, San Juan County, Utah, occurs as a typical tabular-type uranium deposit of the-Colorado Plateau. Uranium-vanadium occurs in the Salt Wash Member of the Jurassic Morrison Formation. Chemical and petrographic analyses were used to determine elemental variation and diagenetic aspects across the orebody. Vanadium is concentrated in the dark clay matrix, which constitutes visible ore. Uranium content is greater above the vanadium zone. Calcium, carbonate carbon, and lead show greater than fifty-fold increase across the ore zone, whereas copper and organic carbon show only a several-fold increase. Large molybdenum concentrations are present in and above the tabular layer, and large selenium concentrations occur below the uranium zone within the richest vanadium zone. Iron is enriched in the vanadium horizon. Chromium is depleted from above the ore and strongly enriched below. Elements that vary directly with the vanadium content include magnesium, iron, selenium, zirconium, strontium, titanium, lead, boron, yttrium, and scandium. The diagenetic sequence is as follows: (1) formation of secondary quartz overgrowths as cement; (2) infilling and lining of remaining pores with amber opaline material; (3) formation of vanadium-rich clay matrix, which has replaced overgrowths as well as quartz grains; (4) replacement of overgrowths and detrital grains by calcite; (5) infilling of pores with barite and the introduction of pyrite and marcasite.

Microwave hydrothermal transformation of amorphous calcium carbonate nanospheres and application in protein adsorption.

PubMed

Qi, Chao; Zhu, Ying-Jie; Chen, Feng

2014-03-26

Calcium carbonate and calcium phosphate are the main components of biominerals. Among all of the forms of biominerals, amorphous calcium carbonate (ACC) and amorphous calcium phosphate (ACP) are the most important forms because they play a pivotal role in the process of biomineralization and are the precursors to the crystalline polymorphs. In this work, we first synthesized ACC in vitro using adenosine 5'-triphosphate disodium salt (ATP) as the stabilizer and investigated the transformation of the ACC under microwave hydrothermal conditions, and ACC/ACP composite nanospheres and carbonated hydroxyapatite (CHA) nanospheres were successfully prepared. In this novel strategy, ATP has two main functions: it serves as the stabilizer for ACC and the phosphorus source for ACP and CHA. Most importantly, the morphology and the size of the ACC precursor can be well-preserved after microwave heating, so it provides a new method for the preparation of calcium phosphate nanostructured materials using phosphorus-containing biomolecule-stabilized ACC as the precursor. Furthermore, the as-prepared ACC/ACP composite nanospheres have excellent biocompatibility and high protein adsorption capacity, indicating that they are promising for applications in biomedical fields such as drug delivery and protein adsorption.

Process development for production of coal/sorbent agglomerates. Final technical report, September 1, 1990--August 31, 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapp, D.M.

1991-12-31

The goal of this work was to develop a process flow diagram to economically produce a clean-burning fuel from fine Illinois coal. To accomplish this, the process of pelletizing fine coal with calcium hydroxide, a sulfur capturing sorbent, was investigated. Carbonation, which is the reaction of calcium hydroxide with carbon dioxide (in the presence of moisture) to produce a bonding matrix of calcium carbonate, was investigated as a method for improving pellet quality and reducing binder costs. Proper moisture level is critical to allow the reaction to occur. If too much moisture is present in a pellet, the pore spacesmore » are filled and carbon dioxide must diffuse through the water to reach the calcium hydroxide and react. This severely slows or stops the reaction. The ideal situation is when there is just enough moisture to coat the calcium hydroxide allowing for the reaction to proceed. The process has been successfully demonstrated on a pilot-scale as a method of hardening iron ore pellets (Imperato, 1966). Two potential combustion options are being considered for the coal/calcium hydroxide pellets: fluidized bed combustors and industrial stoker boilers.« less

Calcium silicates synthesised from industrial residues with the ability for CO2 sequestration.

PubMed

Morales-Flórez, Victor; Santos, Alberto; López, Antonio; Moriña, Isabel; Esquivias, Luis

2014-12-01

This work explored several synthesis routes to obtain calcium silicates from different calcium-rich and silica-rich industrial residues. Larnite, wollastonite and calcium silicate chloride were successfully synthesised with moderate heat treatments below standard temperatures. These procedures help to not only conserve natural resources, but also to reduce the energy requirements and CO2 emissions. In addition, these silicates have been successfully tested as carbon dioxide sequesters, to enhance the viability of CO2 mineral sequestration technologies using calcium-rich industrial by-products as sequestration agents. Two different carbon sequestration experiments were performed under ambient conditions. Static experiments revealed carbonation efficiencies close to 100% and real-time resolved experiments characterised the dynamic behaviour and ability of these samples to reduce the CO2 concentration within a mixture of gases. The CO2 concentration was reduced up to 70%, with a carbon fixation dynamic ratio of 3.2 mg CO2 per g of sequestration agent and minute. Our results confirm the suitability of the proposed synthesis routes to synthesise different calcium silicates recycling industrial residues, being therefore energetically more efficient and environmentally friendly procedures for the cement industry. © The Author(s) 2014.

Synthesis of calcium carbonate using extract components of croaker gill as morphology and polymorph adjust control agent.

PubMed

Chen, Hao; Qing, Chengsong; Zheng, Jiaoling; Liu, Yuxi; Wu, Gang

2016-06-01

Biomimetic synthesis of calcium carbonate with various polymorphs, sizes and morphologies by using organic substrates has become an interesting topic for the last years. Calcium carbonate has been synthesized by the reaction of Na2CO3 and CaCl2 in the presence of extract components of croaker gill. The products were characterized by powder X-ray diffraction (PXRD) and Fourier transform infrared (FT-IR) spectrum, and particle morphologies were observed by scanning electron microscope (SEM). The results show that at lower concentration yellow croaker gill extract has no effect on calcium carbonate crystal polymorph. Calcite was obtained only. But the morphologies of calcite particle change with the increase of the concentration. The corners of the particle change from angular to curved. However, with the further increase of the concentration of yellow croaker gill extract, the calcium carbonate obtained is a mixture of calcite and vaterite. The vaterite component in the mixture rises with increasing concentration of extract solution, indicating that the proteins from the yellow croaker gill during growth play a crucial role in stabilizing and directing the crystal growth. Copyright © 2016 Elsevier B.V. All rights reserved.

Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health.

PubMed

Maresz, Katarzyna

2015-02-01

Inadequate calcium intake can lead to decreased bone mineral density, which can increase the risk of bone fractures. Supplemental calcium promotes bone mineral density and strength and can prevent osteoporosis. Recent scientific evidence, however, suggests that elevated consumption of calcium supplements may raise the risk for heart disease and can be connected with accelerated deposit of calcium in blood-vessel walls and soft tissues. In contrast, vitamin K2 is associated with the inhibition of arterial calcification and arterial stiffening. An adequate intake of vitamin K2 has been shown to lower the risk of vascular damage because it activates matrix GLA protein (MGP), which inhibits the deposits of calcium on the walls. Vitamin K, particularly as vitamin K2, is nearly nonexistent in junk food, with little being consumed even in a healthy Western diet. Vitamin K deficiency results in inadequate activation of MGP, which greatly impairs the process of calcium removal and increases the risk of calcification of the blood vessels. An increased intake of vitamin K2 could be a means of lowering calcium-associated health risks.

Geothermal convection: a mechanism for dolomitization at Enewetak Atoll?

USGS Publications Warehouse

Wilson, A.M.; Sanford, W.; Whitaker, F.; Smart, P.

2000-01-01

Geothermal convection in carbonate platforms could drive massive dolomitization by supplying mass transport of magnesium over long periods and at temperatures high enough to overcome kinetic limitations. Reactive-transport simulations based on Enewetak Atoll show dolomitization in a thin band at a permeability contrast near the base of the platform, which is consistent with field observations of dolomitized Eocene deposits. Dolomitization is predicted at approximately 6% per My at temperatures of 45–60°C, and complete dolomitization could be accomplished in ∼16 My. Calcium enrichment of pore fluids and upward transport of these fluids is established early, prior to 30 ky.

Conversion coatings prepared or treated with calcium hydroxide solutions

NASA Technical Reports Server (NTRS)

Maxey, Jason (Inventor); Nelson, Carl (Inventor); Eylem, Cahit (Inventor); Minevski, Zoran (Inventor); Clarke, Eric (Inventor)

2002-01-01

A conversion coating process that forms a stable and corrosion-resistant oxide layer on metal or metal oxide substrates or layers. Particularly, the conversion coating process involves contacting the metal or metal oxide substrate or layer with the aqueous calcium hydroxide solutions in order to convert the surface of the substrate to a stable metal oxide layer or coating. According to the present invention, the calcium hydroxide solution is prepared by removing carbon dioxide from water or an aqueous solution before introducing the calcium hydroxide. In this manner, formation of calcium carbonate particles is avoided and the porosity of the conversion coating produced by the calcium hydroxide solution is reduced to below about 1%.

Effects of iron and calcium carbonate on the variation and cycling of carbon source in integrated wastewater treatments.

PubMed

Zhimiao, Zhao; Xinshan, Song; Yufeng, Zhao; Yanping, Xiao; Yuhui, Wang; Junfeng, Wang; Denghua, Yan

2017-02-01

Iron and calcium carbonate were added in wastewater treatments as the adjusting agents to improve the contaminant removal performance and regulate the variation of carbon source in integrated treatments. At different temperatures, the addition of the adjusting agents obviously improved the nitrogen and phosphorous removals. TN and TP removals were respectively increased by 29.41% and 23.83% in AC-100 treatment under 1-day HRT. Carbon source from dead algae was supplied as green microbial carbon source and Fe 2+ was supplied as carbon source surrogate. COD concentration was increased to 30mg/L and above, so the problem of the shortage of carbon source was solved. Dead algae and Fe 2+ as carbon source supplement or surrogate played significant role, which was proved by microbial community analysis. According to the denitrification performance in the treatments, dead algae as green microbial carbon source combined with iron and calcium carbonate was the optimal supplement carbon source in wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of crystalline structures in Opuntia ficus-indica.

PubMed

Contreras-Padilla, Margarita; Rivera-Muñoz, Eric M; Gutiérrez-Cortez, Elsa; del López, Alicia Real; Rodríguez-García, Mario Enrique

2015-01-01

This research studies the crystalline compounds present in nopal (Opuntia ficus-indica) cladodes. The identification of the crystalline structures was performed using X-ray diffraction, scanning electron microscopy, mass spectrometry, and Fourier transform infrared spectroscopy. The crystalline structures identified were calcium carbonate (calcite) [CaCO3], calcium-magnesium bicarbonate [CaMg(CO3)2], magnesium oxide [MgO], calcium oxalate monohydrate [Ca(C2O4)•(H2O)], potassium peroxydiphosphate [K4P2O8] and potassium chloride [KCl]. The SEM images indicate that calcite crystals grow to dipyramidal, octahedral-like, prismatic, and flower-like structures; meanwhile, calcium-magnesium bicarbonate structures show rhombohedral exfoliation and calcium oxalate monohydrate is present in a drusenoid morphology. These calcium carbonate compounds have a great importance for humans because their bioavailability. This is the first report about the identification and structural analysis of calcium carbonate and calcium-magnesium bicarbonate in nopal cladodes, as well as the presence of magnesium oxide, potassium peroxydiphosphate and potassium chloride in these plants. The significance of the study of the inorganic components of these cactus plants is related with the increasing interest in the potential use of Opuntia as a raw material of products for the food, pharmaceutical, and cosmetic industries.

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2012 CFR

2012-04-01

..., CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with calcium hydroxide or calcium carbonate. It occurs as a fine white, odorless powder and...

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2013 CFR

2013-04-01

..., CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with calcium hydroxide or calcium carbonate. It occurs as a fine white, odorless powder and...

No calcium-fluoride-like deposits detected in plaque shortly after a sodium fluoride mouthrinse.

PubMed

Vogel, G L; Tenuta, L M A; Schumacher, G E; Chow, L C

2010-01-01

Plaque 'calcium-fluoride-like' (CaF(2)-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 microg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2), centrifuged, and the recovered plaque fluid combined and analyzed using microelectrodes. The plaque mass from aliquot 1 was retained. The plaque mass from aliquot 2 was extracted several times with a solution having the same fluoride, calcium and pH as the plaque fluid in order to extract the plaque CaF(2)-like deposits. The total fluoride in both aliquots was then determined. In a second experiment, the extraction completeness was examined by applying the above procedure to in vitro precipitates containing known amounts of CaF(2)-like deposits. Nearly identical fluoride concentrations were found in both plaque aliquots. The extraction of the CaF(2)-like precipitates formed in vitro removed more than 80% of these deposits. The results suggest that either CaF(2)-like deposits were not formed in plaque or, if these deposits had been formed, they were rapidly lost. The inability to form persistent amounts of CaF(2)-like deposits in plaque may account for the relatively rapid loss of plaque fluid fluoride after the use of conventional fluoride dentifrices or rinses. (c) 2010 S. Karger AG, Basel.

No Calcium-Fluoride-Like Deposits Detected in Plaque Shortly after a Sodium Fluoride Mouthrinse

PubMed Central

Vogel, G.L.; Tenuta, L.M.A.; Schumacher, G.E.; Chow, L.C.

2010-01-01

Plaque ‘calcium-fluoride-like’ (CaF2-like) and fluoride deposits held by biological/bacterial calcium fluoride (Ca-F) bonds appear to be the source of cariostatic concentrations of fluoride in plaque fluid. The aim of this study was to quantify the amounts of plaque fluoride held in these reservoirs after a sodium fluoride rinse. 30 and 60 min after a 228 μg/g fluoride rinse, plaque samples were collected from 11 volunteers. Each sample was homogenized, split into 2 aliquots (aliquots 1 and 2), centrifuged, and the recovered plaque fluid combined and analyzed using microelectrodes. The plaque mass from aliquot 1 was retained. The plaque mass from aliquot 2 was extracted several times with a solution having the same fluoride, calcium and pH as the plaque fluid in order to extract the plaque CaF2-like deposits. The total fluoride in both aliquots was then determined. In a second experiment, the extraction completeness was examined by applying the above procedure to in vitro precipitates containing known amounts of CaF2-like deposits. Nearly identical fluoride concentrations were found in both plaque aliquots. The extraction of the CaF2-like precipitates formed in vitro removed more than 80% of these deposits. The results suggest that either CaF2-like deposits were not formed in plaque or, if these deposits had been formed, they were rapidly lost. The inability to form persistent amounts of CaF2-like deposits in plaque may account for the relatively rapid loss of plaque fluid fluoride after the use of conventional fluoride dentifrices or rinses. PMID:20185917

Acid rain attack on outdoor sculpture in perspective

NASA Astrophysics Data System (ADS)

Livingston, Richard A.

2016-12-01

A major concern motivating research in acid rain materials effects has been the potential for damage to cultural heritage, particularly outdoor marble and bronze sculpture. However, a combination of field and laboratory studies has failed to show a correlation between rain pH and loss of materials. In order to understand this counterintuitive lack of acid rain effect, an aqueous geochemical modeling approach was used to analyze rain runoff chemistry for the relative importance of acid rain neutralization, dry deposition, and in the case of marble, natural carbonate dissolution. This approach involved the development of pH - SO42- phase diagrams for marble (calcium carbonate) and bronze (copper) under ambient environmental conditions. This then enabled reaction path modeling of the acid neutralization process using the pH range typically found in wet deposition (3.5-6). The results were for marble that the theoretical maximum amount of Ca2+ ion that could be lost due acid rain neutralization would be 0.158 mmol/l compared to 10.5 mmol/l by dry deposition, and for bronze, the Cu2+ ion losses would be 0.21 mmol/l and 47.3 mmol/l respectively. Consequently dry deposition effects on these materials have the potential to dominate over wet deposition effects. To test these predictions the geochemical models were applied to examples of data sets from mass balance (runoff vs rainfall) studies on a marble statue in New York City and some bronze memorial plaques at Gettysburg PA. Although these data sets were collected in the early 1980s they remain valid for demonstrating the mass balance method. For the marble statue, the mean Ca2+ losses by dry deposition was about 69% of the total compared 0.3% for acid rain neutralization, which was less than the natural carbonate dissolution losses of 0.8%. For the bronze, the mean Cu2+ losses were 70.6% by SO42- dry deposition and 23% by NO3- dry deposition compared to 6.4% by acid rain neutralization. Thus for both cases the wet deposition component was less than the variability of the dry deposition components, which explains the observed lack of correlation between the rain pH and the material losses. In addition, for the marble case, there was evidence for HCl acid vapor attack resulting from nitric acid/sea salt interactions and for bronze, ammonium ion may be important. In both cases, significant imbalances suggested that unmeasured organic acids may have a significant effect.

Elevated CO2 affects shell dissolution rate but not calcification rate in a marine snail.

PubMed

Nienhuis, Sarah; Palmer, A Richard; Harley, Christopher D G

2010-08-22

As CO(2) levels increase in the atmosphere, so too do they in the sea. Although direct effects of moderately elevated CO(2) in sea water may be of little consequence, indirect effects may be profound. For example, lowered pH and calcium carbonate saturation states may influence both deposition and dissolution rates of mineralized skeletons in many marine organisms. The relative impact of elevated CO(2) on deposition and dissolution rates are not known for many large-bodied organisms. We therefore tested the effects of increased CO(2) levels--those forecast to occur in roughly 100 and 200 years--on both shell deposition rate and shell dissolution rate in a rocky intertidal snail, Nucella lamellosa. Shell weight gain per day in live snails decreased linearly with increasing CO(2) levels. However, this trend was paralleled by shell weight loss per day in empty shells, suggesting that these declines in shell weight gain observed in live snails were due to increased dissolution of existing shell material, rather than reduced production of new shell material. Ocean acidification may therefore have a greater effect on shell dissolution than on shell deposition, at least in temperate marine molluscs.

Fabrication of mineralized electrospun PLGA and PLGA/gelatin nanofibers and their potential in bone tissue engineering.

PubMed

Meng, Z X; Li, H F; Sun, Z Z; Zheng, W; Zheng, Y F

2013-03-01

Surface mineralization is an effective method to produce calcium phosphate apatite coating on the surface of bone tissue scaffold which could create an osteophilic environment similar to the natural extracellular matrix for bone cells. In this study, we prepared mineralized poly(D,L-lactide-co-glycolide) (PLGA) and PLGA/gelatin electrospun nanofibers via depositing calcium phosphate apatite coating on the surface of these nanofibers to fabricate bone tissue engineering scaffolds by concentrated simulated body fluid method, supersaturated calcification solution method and alternate soaking method. The apatite products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) methods. A large amount of calcium phosphate apatite composed of dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HA) and octacalcium phosphate (OCP) was deposited on the surface of resulting nanofibers in short times via three mineralizing methods. A larger amount of calcium phosphate was deposited on the surface of PLGA/gelatin nanofibers rather than PLGA nanofibers because gelatin acted as nucleation center for the formation of calcium phosphate. The cell culture experiments revealed that the difference of morphology and components of calcium phosphate apatite did not show much influence on the cell adhesion, proliferation and activity. Copyright © 2012 Elsevier B.V. All rights reserved.

The fate of calcium carbonate nanoparticles administered by oral route: absorption and their interaction with biological matrices

PubMed Central

Lee, Jeong-A; Kim, Mi-Kyung; Kim, Hyoung-Mi; Lee, Jong Kwon; Jeong, Jayoung; Kim, Young-Rok; Oh, Jae-Min; Choi, Soo-Jin

2015-01-01

Background Orally administered particles rapidly interact with biological fluids containing proteins, enzymes, electrolytes, and other biomolecules to eventually form particles covered by a corona, and this corona potentially affects particle uptake, fate, absorption, distribution, and elimination in vivo. This study explored relationships between the biological interactions of calcium carbonate particles and their biokinetics. Methods We examined the effects of food grade calcium carbonates of different particle size (nano [N-Cal] and bulk [B-Cal]: specific surface areas of 15.8 and 0.83 m2/g, respectively) on biological interactions in in vitro simulated physiological fluids, ex vivo biofluids, and in vivo in gastrointestinal fluid. Moreover, absorption and tissue distribution of calcium carbonates were evaluated following a single dose oral administration to rats. Results N-Cal interacted more with biomatrices than bulk materials in vitro and ex vivo, as evidenced by high fluorescence quenching ratios, but it did not interact more actively with biomatrices in vivo. Analysis of coronas revealed that immunoglobulin, apolipoprotein, thrombin, and fibrinogen, were the major corona proteins, regardless of particle size. A biokinetic study revealed that orally delivered N-Cal was more rapidly absorbed into the blood stream than B-Cal, but no significant differences were observed between the two in terms of absorption efficiencies or tissue distributions. Both calcium carbonates were primarily present as particulate forms in gastrointestinal fluids but enter the circulatory system in dissolved Ca2+, although both types showed partial phase transformation to dicalcium phosphate dihydrate. Relatively low dissolution (about 4%), no remarkable protein–particle interaction, and the major particulate fate of calcium carbonate in vivo gastrointestinal fluids can explain its low oral absorption (about 4%) regardless of particle size. Conclusion We conclude that calcium carbonate nanoparticles can act more actively with biological matrices in vitro and ex vivo, but that in vivo, their biological interactions and biokinetics are not affected by particle size. PMID:25848250

The fate of calcium carbonate nanoparticles administered by oral route: absorption and their interaction with biological matrices.

PubMed

Lee, Jeong-A; Kim, Mi-Kyung; Kim, Hyoung-Mi; Lee, Jong Kwon; Jeong, Jayoung; Kim, Young-Rok; Oh, Jae-Min; Choi, Soo-Jin

2015-01-01

Orally administered particles rapidly interact with biological fluids containing proteins, enzymes, electrolytes, and other biomolecules to eventually form particles covered by a corona, and this corona potentially affects particle uptake, fate, absorption, distribution, and elimination in vivo. This study explored relationships between the biological interactions of calcium carbonate particles and their biokinetics. We examined the effects of food grade calcium carbonates of different particle size (nano [N-Cal] and bulk [B-Cal]: specific surface areas of 15.8 and 0.83 m(2)/g, respectively) on biological interactions in in vitro simulated physiological fluids, ex vivo biofluids, and in vivo in gastrointestinal fluid. Moreover, absorption and tissue distribution of calcium carbonates were evaluated following a single dose oral administration to rats. N-Cal interacted more with biomatrices than bulk materials in vitro and ex vivo, as evidenced by high fluorescence quenching ratios, but it did not interact more actively with biomatrices in vivo. Analysis of coronas revealed that immunoglobulin, apolipoprotein, thrombin, and fibrinogen, were the major corona proteins, regardless of particle size. A biokinetic study revealed that orally delivered N-Cal was more rapidly absorbed into the blood stream than B-Cal, but no significant differences were observed between the two in terms of absorption efficiencies or tissue distributions. Both calcium carbonates were primarily present as particulate forms in gastrointestinal fluids but enter the circulatory system in dissolved Ca(2+), although both types showed partial phase transformation to dicalcium phosphate dihydrate. Relatively low dissolution (about 4%), no remarkable protein-particle interaction, and the major particulate fate of calcium carbonate in vivo gastrointestinal fluids can explain its low oral absorption (about 4%) regardless of particle size. We conclude that calcium carbonate nanoparticles can act more actively with biological matrices in vitro and ex vivo, but that in vivo, their biological interactions and biokinetics are not affected by particle size.

Model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory.

PubMed

Fletcher, Paul D I; Savory, Luke D; Woods, Freya; Clarke, Andrew; Howe, Andrew M

2015-03-17

With the aim of elucidating the details of enhanced oil recovery by surfactant solution flooding, we have determined the detailed behavior of model systems consisting of a packed column of calcium carbonate particles as the porous rock, n-decane as the trapped oil, and aqueous solutions of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The AOT concentration was varied from zero to above the critical aggregation concentration (cac). The salt content of the aqueous solutions was varied to give systems of widely different, post-cac oil-water interfacial tensions. The systems were characterized in detail by measuring the permeability behavior of the packed columns, the adsorption isotherms of AOT from the water to the oil-water interface and to the water-calcium carbonate interface, and oil-water-calcium carbonate contact angles. Measurements of the percent oil recovery by pumping surfactant solutions into calcium carbonate-packed columns initially filled with oil were analyzed in terms of the characterization results. We show that the measured contact angles as a function of AOT concentration are in reasonable agreement with those calculated from values of the surface energy of the calcium carbonate-air surface plus the measured adsorption isotherms. Surfactant adsorption onto the calcium carbonate-water interface causes depletion of its aqueous-phase concentration, and we derive equations which enable the concentration of nonadsorbed surfactant within the packed column to be estimated from measured parameters. The percent oil recovery as a function of the surfactant concentration is determined solely by the oil-water-calcium carbonate contact angle for nonadsorbed surfactant concentrations less than the cac. For surfactant concentrations greater than the cac, additional oil removal occurs by a combination of solubilization and emulsification plus oil mobilization due to the low oil-water interfacial tension and a pumping pressure increase.

The influence of electron discharge and magnetic field on calcium carbonate (CaCO{sub 3}) precipitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Putro, Triswantoro, E-mail: tris@physics.its.ac.id; Endarko, E-mail: endarko@physics.its.ac.id

The influences of electron discharge and magnetic field on calcium carbonate (CaCO{sub 3}) precipitation in water have been successfully investigated. The study used three pairs of magnetic field 0.1 T whilst the electron discharge was generated from television flyback transformer type BW00607 and stainless steel SUS 304 as an electrode. The water sample with an initial condition of 230 mg/L placed in the reactor with flow rate 375 mL/minutes, result showed that the electron discharge can be reduced contain of calcium carbonate the water sample around 17.39% within 2 hours. Meanwhile for the same long period of treatment and flow rate, aroundmore » 56.69% from initial condition of 520 mg/L of calcium carbonate in the water sample can be achieved by three pairs of magnetic field 0.1 T. When the combination of three pairs of magnetic field 0.1 T and the electron discharge used for treatment, the result showed that the combination of electron discharge and magnetic field methods can be used to precipitate calcium carbonate in the water sample 300 mg/L around 76.66% for 2 hours of treatment. The study then investigated the influence of the polar position of the magnetic field on calcium carbonate precipitation. Two positions of magnetic field were tested namely the system with alternated polar magnetics and the system without inversion of the polar magnetics. The influence of the polar position showed that the percentage reduction in levels of calcium carbonate in the water sample (360 mg/L) is significant different. Result showed that the system without inversion of the polar magnetics is generally lower than the system with alternated polar magnetics, with reduction level at 30.55 and 57.69%, respectively.« less

Cathodic behaviour of stainless steel in coastal Indian seawater: calcareous deposits overwhelm biofilms.

PubMed

Eashwar, M; Subramanian, G; Palanichamy, S; Rajagopal, G; Madhu, S; Kamaraj, P

2009-01-01

Type-316 stainless steel (SS) was investigated as the cathode in galvanic couples in full-strength seawater from the Gulf of Mannar on the southeast coast of India. Tests were devised to examine the impact of SS cathodes on anode materials with or without the accrual of marine biofilms. Biofilmed SS cathodes significantly enhanced the rate of corrosion of nickel, causing noble shifts in the couple potentials. With mild steel and zinc as the anodes, calcareous deposits developed quite rapidly on the SS cathodes and led to a significant reduction of bacterial numbers. The calcareous deposits also caused substantial reduction of galvanic corrosion rates for mild steel, whereas there was no difference for zinc. The deposits were identified by XRD as essentially carbonates, oxides and hydroxides of calcium and magnesium. Potentiodynamic polarization performed on the actual couples after disconnection and equilibration provided reasonable interpretations of the galvanic corrosion trends. Data from this work suggest that a potential of about -0.70 V vs. saturated calomel electrode (SCE) should provide optimum protection of SS in warmer, full-strength seawater that supports the precipitation of calcareous deposits. The criterion commonly recommended for temperate conditions of lower water temperature and estuarine waters of lower alkalinity is -1.0 V (SCE).

The effect of crystal structure of TiO2 nanotubes on the formation of calcium phosphate coatings during biomimetic deposition

NASA Astrophysics Data System (ADS)

Liu, Yi; Kim, Sun; McLeod, John A.; Li, Jun; Guo, Xiaoxuan; Sham, Tsun-Kong; Liu, Lijia

2017-02-01

The crystallization process of bioactive calcium phosphate (CaP) species via biomimetic deposition onto anodic TiO2 nanotubes is investigated. The porous surface of nanostructured TiO2 provides an ideal substrate for CaP crystallization. The compositions of CaP coatings are studied using X-ray absorption near-edge structures (XANES) at the Ca K-edge. Using detection modes with different probing depths, both the surface of the CaP coating and the CaP-TiO2 interface are simultaneously analyzed. Calcium phosphate (CaP) species, such as hydroxyapatite (HAp), octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O, OCP), brushite (CaHPO4·2H2O, DCPD), and amorphous calcium phosphate (ACP), are found in the CaP coatings. TiO2 nanotubes of amorphous and anatase phases are comparatively studied to determine their effect on the efficiency of CaP formation and the phase transformation among CaP species in prolonged deposition time. It is found the composition of CaP coating has a strong dependency on the crystal structure of TiO2 substrate and the kinetics (deposition time).

Enamel-like apatite crown covering amorphous mineral in a crayfish mandible

PubMed Central

Bentov, Shmuel; Zaslansky, Paul; Al-Sawalmih, Ali; Masic, Admir; Fratzl, Peter; Sagi, Amir; Berman, Amir; Aichmayer, Barbara

2012-01-01

Carbonated hydroxyapatite is the mineral found in vertebrate bones and teeth, whereas invertebrates utilize calcium carbonate in their mineralized organs. In particular, stable amorphous calcium carbonate is found in many crustaceans. Here we report on an unusual, crystalline enamel-like apatite layer found in the mandibles of the arthropod Cherax quadricarinatus (freshwater crayfish). Despite their very different thermodynamic stabilities, amorphous calcium carbonate, amorphous calcium phosphate, calcite and fluorapatite coexist in well-defined functional layers in close proximity within the mandible. The softer amorphous minerals are found primarily in the bulk of the mandible whereas apatite, the harder and less soluble mineral, forms a wear-resistant, enamel-like coating of the molar tooth. Our findings suggest a unique case of convergent evolution, where similar functional challenges of mastication led to independent developments of structurally and mechanically similar, apatite-based layers in the teeth of genetically remote phyla: vertebrates and crustaceans. PMID:22588301

Oil shale retorting and combustion system

DOEpatents

Pitrolo, Augustine A.; Mei, Joseph S.; Shang, Jerry Y.

1983-01-01

The present invention is directed to the extraction of energy values from l shale containing considerable concentrations of calcium carbonate in an efficient manner. The volatiles are separated from the oil shale in a retorting zone of a fluidized bed where the temperature and the concentration of oxygen are maintained at sufficiently low levels so that the volatiles are extracted from the oil shale with minimal combustion of the volatiles and with minimal calcination of the calcium carbonate. These gaseous volatiles and the calcium carbonate flow from the retorting zone into a freeboard combustion zone where the volatiles are burned in the presence of excess air. In this zone the calcination of the calcium carbonate occurs but at the expense of less BTU's than would be required by the calcination reaction in the event both the retorting and combustion steps took place simultaneously. The heat values in the products of combustion are satisfactorily recovered in a suitable heat exchange system.

Reequilibration of fluid inclusions in low-temperature calcium-carbonate cement

NASA Astrophysics Data System (ADS)

Goldstein, Robert H.

1986-09-01

Calcium-carbonate cements precipitated in low-temperature, near-surface, vadose environments contain fluid inclusions of variable vapor-to-liquid ratios that yield variable homogenization temperatures. Cements precipitated in low-temperature, phreatic environments contain one-phase, all-liquid fluid inclusions. Neomorphism of unstable calcium-carbonate phases may cause reequilibration of fluid inclusions. Stable calcium-carbonate cements of low-temperature origin, which have been deeply buried, contain fluid inclusions of variable homogenization temperature and variable salt composition. Most inclusion fluids are not representative of the fluids present during cement growth and are more indicative of burial pore fluids. Therefore, low-temperature fluid inclusions probably reequilibrate with burial fluids during progressive burial. Reequilibration is likely caused by high internal pressures in inclusions which result in hydrofracturing. The resulting fluid-inclusion population could contain a nearly complete record of burial fluids in which a particular rock has been bathed. *Present address: Department of Geology, University of Kansas, Lawrence, Kansas 66045

Presence and dehydration of ikaite, calcium carbonate hexahydrate, in frozen shrimp shell.

PubMed

Mikkelsen, A; Andersen, A B; Engelsen, S B; Hansen, H C; Larsen, O; Skibsted, L H

1999-03-01

Ikaite, calcium carbonate hexahydrate, has by means of X-ray diffraction analyses of frozen samples been identified as the mineral component of the white spots formed in the shell of frozen shrimp during storage. When the shrimp thaw and the shell material is dried and kept at room temperature, ikaite rapidly transforms into a mixture of anhydrous calcium carbonate forms. X-ray diffraction analyses and Raman spectra of synthetic ikaite as well as the dehydration product confirm the assignments, and the rate constant for dehydration is approximately 7 x 10(-)(4) s(-)(1) at ambient temperature. Differential scanning calorimetry showed that dehydration of synthetic ikaite is an entropy-driven, athermal process and confirms that a single first-order reaction is rate-determining. Ikaite is found to be stable in aqueous solution at temperatures below 5 degrees C and in the shell of frozen shrimps but decomposes on thawing to form anhydrous calcium carbonates.

Development of calcium bodies in Hylonsicus riparius (Crustacea: Isopoda).

PubMed

Vittori, Miloš; Khurshed, Mohammed; Picavet, Daisy I; van Noorden, Cornelis J F; Štrus, Jasna

2018-03-01

Calcium bodies are internal epithelial sacs found in terrestrial isopods of the family Trichoniscidae that contain a mineralized extracellular matrix that is deposited and resorbed in relation to the molt cycle. Calcium bodies in several trichoniscids are filled with bacteria, the function of which is currently unknown. The woodlouse Hyloniscus riparius differs from other trichoniscids in that it possesses two different pairs of calcium bodies, the posterior pair being filled with bacteria and the anterior pair being devoid of bacteria. We explored the development of these organs and bacterial colonization of their lumen during the postmarsupial development with the use of optical clearing and whole-body confocal imaging of larval and juvenile stages. Our results show that calcium bodies are formed as invaginations of the epidermis in the region of intersegmental membranes during the postmarsupial development. The anterior pair of calcium bodies is generated during the first postmarsupial manca stage, whereas the posterior calcium bodies first appear in juveniles and are immediately colonized by bacteria, likely through a connection between the calcium body lumen and the body surface. Mineral is deposited in calcium bodies as soon as they are present. Copyright © 2018 Elsevier Ltd. All rights reserved.

State and solubility of cadmium as related to xenotic inorganic phases generated homogeneously in soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, W.J.

The state and solubility of cadmium in waste-treated soils was investigated. Three sets of experiments were designed to elucidate solid phase control of soil solution cadmium. First, the soil solution composition of two soils amended with either sludge or metal contaminated mulch was examined to determine the presence of anions capable of precipitating or co-precipitating cadmium. Results indicated that no known pure solid phases of cadmium developed but that high concentrations of phosphate, sulfate and carbonate apparently influenced cadmium solubility. Secondly, three soils were amended with 10 ug of cadmium as cadmium acetate/g of soil. Three different levels of glycerophosphate,more » cysteine and acetate were added to the soils and incubated at constant temperature and water content in order to release phosphate, sulfate and alkalinity under conditions conducive for homogeneous precipitation. Another set of treatments was prepared in the same fashion with an additional amendment of calcium carbonate to raise soil pH's to 7.0. In the presence of sulfate, cadmium solubility increased with no apparent solid phase formation. The addition of calcium carbonate shifted solid phase control to either calcium carbonate or calcium sulfate. The generation of alkalinity by acetate addition produced solid phase calcium carbonate which in turn controlled cadmium solubility through chemisorption of cadmium on calcite surfaces. In the presence of monobasic calcium phosphate, cadmium was interfacially adsorbed. In the presence of dibasic calcium phosphate, however, cadmium was homogeneously precipitated in the host crystal suggesting possible solid solution.« less

Epidermal carbonic anhydrase activity and exoskeletal metal content during the molting cycle of the blue crab, Callinectes sapidus.

PubMed

Calhoun, Stacy; Zou, Enmin

2016-03-01

During the crustacean molting cycle, the exoskeleton is first mineralized in postmolt and intermolt and then presumably demineralized in premolt in order for epidermal retraction to occur. The mineralization process calls for divalent metal ions, such as Ca(2+) and Mg(2+) , and bicarbonate ions whereas protons are necessary for dissolution of carbonate salts. Carbonic anhydrase (CA) has been suggested to be involved in exoskeletal mineralization by providing bicarbonate ions through catalyzing the reaction of carbon dioxide hydration. However, results of earlier studies on the role of epidermal CA in metal incorporation in crustacean exoskeleton are not consistent. This study was aimed to provide further evidence to support the notion that epidermal CA is involved in exoskeletal mineralization using the blue crab, Callinectes sapidus (Rathbun 1896), as the model crustacean. Significant increases first in calcium and magnesium then in manganese post-ecdysis indicate significant metal deposition during postmolt and intermolt. Significant positive correlation between calcium or magnesium content and epidermal CA activity in postmolt and intermolt constitutes evidence that CA is involved in the mineralization of the crustacean exoskeleton. Additionally, we proposed a hypothetical model to describe the role of epidermal CA in both mineralization and demineralization of the exoskeleton based on the results of epidermal CA activity and exoskeletal metal content during the molting cycle. Furthermore, we found that the pattern of epidermal CA activity during the molting cycle of C. sapidus is similar to that of ecdysteroids reported for the same species, suggesting that epidermal CA activity may be under control of the molting hormones. © 2016 Wiley Periodicals, Inc.

Evaluation and control of corrosion and encrustation in tube wells of the Indus Plains, West Pakistan

USGS Publications Warehouse

Clarke, Frank Eldridge; Barnes, Ivan

1969-01-01

Seepage from rivers and irrigation canals has contributed to waterlogging and soil salinization problems in much of the Indus Plains of West Pakistan. These problems are being overcome in part by tube-well dewatering and deep leaching of salinized soils. The ground waters described here are anaerobic and some are supersaturated with troublesome minerals such as calcium carbonate (calcite) and iron carbonate (siderite). These waters are moderately corrosive to steel. Some wells contain sulfate-reducing bacteria, which catalyze corrosion, and pH-electrode potential relationships favorable to the solution of iron also are rather common. Corrosion is concentrated in the relatively active (anodic) saw slots of water-well filter pipes (screens), where metal loss is least tolerable. Local changes in chemical properties of the water, because of corrosion, apparently cause deposition of calcium carbonate, iron carbonate, and other minerals which clog the filter pipes. In some places well capacities are seriously reduced in very short periods of time. There appears to be no practicable preventive treatment for corrosion and encrustation in these wells. Even chemical sterilization for bacterial control has yielded poor results. Periodic rehabilitation by down-hole blasting or by other effective mechanical or chemical cleaning methods will prolong well life. It may be possible to repair severely damaged well screens by inserting perforated sleeves of plastic or other inert material. The most promising approach to future, well-field development is to use filter pipes of epoxy-resin-bonded fiber glass, stainless steel, or other inert material which minimizes both corrosion and corrosion-catalyzed encrustation. Fiberglass plastic pipe appears to be the most economically practicable construction material at this time and already is being used with promising results.

Chronicling ice shelf history in the sediments left behind

NASA Astrophysics Data System (ADS)

Rosenheim, B. E.; Subt, C.; Shevenell, A.; Guitard, M.; Vadman, K. J.; DeCesare, M.; Wellner, J. S.; Bart, P. J.; Lee, J. I.; Domack, E. W.; Yoo, K. C.; Hayes, J. M.

2017-12-01

Collapsing and retreating ice shelves leave unmistakable sediment sequences on the Antarctic margin. These sequences tell unequivocal stories of collapse or retreat through a typical progression of sub-ice shelf diamicton (marking the past positions of grounding lines), sequentially overlain by a granulated facies from beneath the ice shelf, ice rafted debris from the calving line, and finally open marine sediment. The timelines to these stories, however, are troublesome. Difficulties in chronicling these stories recorded in sediment have betrayed their importance to our understanding of a warming world in many cases. The difficulties involve the concerted lack of preservation/production of calcium carbonate tests from the water column above and admixture of relict organic material from older sources of carbon. Here, we summarize our advances in the last decade of overcoming difficulties associated with the paucity of carbonate and creating chronologies of ice shelf retreat into the deglacial history of Antarctica by exploiting the range of thermochemical stability in organic matter (Ramped PyrOx) from these sediment sequences. We describe our success in comparing Ramped PyrOx 14C dates with foraminiferal dates, the relationship between sediment facies and radiocarbon age spectrum, and our ability to push limits of dating sediments deposited underneath ice shelves. With attention to the caveats of recent dating developments, we summarize expectations that geologist should have when coring the Antarctic margins to discern deglacial history. Perhaps most important among these expectations is the ability to design coring expeditions without regard to our ability to date calcium carbonate microfossils within the cores, in essence removing suspense of knowing whether cores taken from crucial paleo ice channels and other bathymetric features will ultimately yield a robust chronology for its sedimentary sequence.

Cool episodes in Early Tertiary Arctic climate: Evidence from Svalbard

NASA Astrophysics Data System (ADS)

Spielhagen, R. F.; Tripati, A.

2009-04-01

The Arctic is a climatically sensitive and important region. However, very little is known about the climatic and oceanographic evolution of the area, particularly prior to the Neogene. Until recently, the Arctic was assumed to be characterized by relatively warm conditions during the early Cenozoic. The Early Tertiary sedimentary sequence on Svalbard contains several layers with coal seams and broad-leaved plants which were commonly accepted as indicators of a generally temperate-warm climate. Here we report on the intermittent occurrence of certain temperature indicators in the succession, which may represent the first northern high-latitude record of near-freezing temperatures for the early Cenozoic. Besides the findings of probably ice-rafted erratic clasts in the Paleocene and Eocene sandstones and shales, we note especially the occurrence of glendonites which are pseudomorphs of calcite after ikaite (calcium carbonate hexahydrate). We measured the chemical composition of Svalbard glendonites which is almost identical to that of similar pseudomorphs from the Lower Cretaceaous of Northern Canada. Mass spectrometric analyses of the glendonite calcite gave very low carbon isotope values. These values suggest a provenance of the calcium carbonate from marine organic carbon and connect our glendonites to the precursor mineral ikaite which has similar low values. Since a variety of studies has demonstrated that ikaite is stable only at temperatures close to freezing point, we have to infer low temperatures also for the deepositional environment of which the sediments were deposited that now hold glendonites. These results imply the occurrence of cooling phases episodically during the warm background climate of the Paleocene and Eocene, suggesting that temperature variability was much greater than previously recognized.

Evidence From Svalbard for Cool Episodes in Early Tertiary Arctic Climate

NASA Astrophysics Data System (ADS)

Spielhagen, R. F.; Tripati, A.; Mac Niocaill, C.

2008-12-01

The Arctic is a climatically sensitive and important region. However, very little is known about the climatic and oceanographic evolution of the area, particularly prior to the Neogene. Until recently, the Arctic was assumed to be characterized by relatively warm conditions during the early Cenozoic. The Early Tertiary sedimentary sequence on Svalbard contains several layers with coal seams and broad-leaved plants which were commonly accepted as indicators of a generally temperate-warm climate. Here we report on the intermittent occurrence of certain temperature indicators in the succession, which may represent the first northern high- latitude record of near-freezing temperatures for the early Cenozoic. Besides the findings of probably ice- rafted erratic clasts in the Paleocene and Eocene sandstones and shales, we note especially the occurrence of glendonites which are pseudomorphs of calcite after ikaite (calcium carbonate hexahydrate). Stratigraphic control for the most important glendonite layers was improved by paleomagnetic investigations on the host sediment. We measured the chemical composition of Svalbard glendonites which is almost identical to that of similar pseudomorphs from the Lower Cretaceaous of Northern Canada. Mass spectrometric analyses of the glendonite calcite gave very low carbon isotope values. These values suggest a provenance of the calcium carbonate from marine organic carbon and connect our glendonites to the precursor mineral ikaite which has similar low values. Since a variety of studies has demonstrated that ikaite is stable only at temperatures close to freezing point, we have to infer low temperatures also for the deepositional environment of which the sediments were deposited that now hold glendonites. These results imply the occurrence of cooling phases episodically during the warm background climate of the Paleocene and Eocene, suggesting that temperature variability was much greater than previously recognized.

Potential Evaporite Biomarkers from the Dead Sea

NASA Technical Reports Server (NTRS)

Morris, Penny A.; Wentworth, Susan J.; Thomas-Keprta, Kathie; Allen, Carlton C.; McKay, David S.

2001-01-01

The Dead Sea is located on the northern branch of the African-Levant Rift systems. The rift system, according to one model, was formed by a series of strike slip faults, initially forming approximately two million years ago. The Dead Sea is an evaporite basin that receives freshwater from springs and from the Jordan River. The Dead Sea is different from other evaporite basins, such as the Great Salt Lake, in that it possesses high concentrations of magnesium and has an average pH of 6.1. The dominant cation in the Great Salt Lake is sodium, and the pH is 7.7. Calcium concentrations are also higher in the Dead Sea than in the Great Salt Lake. Both basins are similar in that the dominant anion is chlorine and the salinity levels are approximately 20 %. Other common cations that have been identified from the waters of the Dead Sea and the Great Salt Lake include sodium and potassium. A variety of Archea, Bacteria, and a single genus of a green algal, Dunaliella, has been described from the Dead Sea. Earlier studies concentrated on microbial identification and analysis of their unique physiology that allows them to survive in this type of extreme environment. Potential microbial fossilization processes, microbial fossils, and the metallic ions associated with fossilization have not been studied thoroughly. The present study is restricted to identifying probable microbial morphologies and associated metallic ions. XRD (X Ray Diffraction) analysis indicates the presence of halite, quartz, and orthoclase feldspar. In addition to these minerals, other workers have reported potassium chloride, magnesium bromide, magnesium chloride, calcium chloride, and calcium sulfate. Halite, calcium sulfate, and orthoclase were examined in this report for the presence of microbes, microbially induced deposits or microbial alteration. Neither the gypsum nor the orthoclase surfaces possesses any obvious indications of microbial life or fossilization. The sand-sized orthoclase particles are weathered with 122 extensive fan-shaped mineral deposits. The gypsum deposits are associated with halite minerals and also exhibit extensive weathering. Halite minerals represent the only substrates that have probable rod-shaped microbial structures with long, filamentous, apical extensions. EDS (energy dispersive x-ray) analysis of the putative microbes indicates elevated calcium levels that are enriched with magnesium. The rod-shaped structures exhibit possible fossilization stages. Rhombohedralshaped minerals of magnesium-enriched calcium carbonate are deposited on the microbial surfaces, and eventually coat the entire microbial surface. The sodium chloride continues to crystallize on nearby halite surface and even crystallizes on the fossilized microbial remains. The putative fossils are found exclusively on halite surfaces, and all contained elevated levels of calcium magnesium cations. Both of these metallic cations are associated with microbial activity and fossilization. Their morphological diversity is low in comparison with the reported living Dead Sea microbial population. If we examine the fossil record for multicellular organisms, fossilization rates are lower for soft-bodied organisms than for those possessing hard parts, i.e. shells, bones. For example, smaller, single celled organisms would have a smaller chance of fossilization; their fossilized shapes could be mistaken for abiotic products. Another consideration is that dead organisms in the water column are probably utilized as a food source by other microbes before fossilization processes are completed. This may be an important consideration as we attempt to model and interpret ancient microbial environments either on Earth or on Mars.

Characterization of calcium phosphate coatings deposited by Nd:YAG laser ablation at 355 nm: influence of thickness.

PubMed

Fernández-Pradas, J M; Clèries, L; Sardin, G; Morenza, J L

2002-05-01

Calcium phosphate coatings were deposited by pulsed laser ablation with a radiation of 355 nm from a Nd:YAG laser. All the coatings were obtained at the same conditions, but deposition was stopped after different number of pulses to get coatings with different thickness. The influence of thickness in the structural and mechanical properties of the coatings was investigated. Coatings structure was characterised by scanning electron microscopy, grazing incidence X-ray diffractometry and Raman spectroscopy. The mechanical properties were evaluated by scratch test. The morphology of the coatings is dominated by the presence of droplets. The coatings are composed mainly of hydroxyapatite, alpha tricalcium phosphate and amorphous calcium phosphate. Thinner coatings withstand higher loads of failure in the scratch test.

Structure and function of matrix proteins and peptides in the biomineral formation in crustaceans.

PubMed

Nagasawa, Hiromichi

2011-01-01

Crustaceans have hard cuticle with layered structure, which is composed mainly of chitin, proteins, and calcium carbonate. Crustaceans grow by shedding the old cuticle and replacing it with a new one. Decalcification in the cuticle during the pre-molt stage and concomitant calcification in the stomach to form gastroliths observed in some crustacean species are triggered by the molting hormone. Various proteins and peptides have been identified from calcified cuticle and gastroliths, and their functions have been examined in terms of calcification and interaction with chitin. Acidic nature of matrix proteins is important for recruitment of calcium ions and interaction with calcium carbonate. Examination of the relationship between amino acid sequence containing acidic amino acid residues and calcification inhibitory activity revealed that the potency did not depend on the sequence but on the number of acidic amino acid residues. Calcium carbonate in the calcified tissues of crustaceans is amorphous in many cases. Crustaceans take a strategy to induce and maintain amorphous calcium carbonate by using low-molecular-weight phosphorus compounds.

Pressure induced polymerization of acetylide anions in CaC2 and 107 fold enhancement of electrical conductivity.

PubMed

Zheng, Haiyan; Wang, Lijuan; Li, Kuo; Yang, Youyou; Wang, Yajie; Wu, Jiajia; Dong, Xiao; Wang, Chun-Hai; Tulk, Christopher A; Molaison, Jamie J; Ivanov, Ilia N; Feygenson, Mikhail; Yang, Wenge; Guthrie, Malcolm; Zhao, Yusheng; Mao, Ho-Kwang; Jin, Changqing

2017-01-01

Transformation between different types of carbon-carbon bonding in carbides often results in a dramatic change of physical and chemical properties. Under external pressure, unsaturated carbon atoms form new covalent bonds regardless of the electrostatic repulsion. It was predicted that calcium acetylide (also known as calcium carbide, CaC 2 ) polymerizes to form calcium polyacetylide, calcium polyacenide and calcium graphenide under high pressure. In this work, the phase transitions of CaC 2 under external pressure were systematically investigated, and the amorphous phase was studied in detail for the first time. Polycarbide anions like C 6 6- are identified with gas chromatography-mass spectrometry and several other techniques, which evidences the pressure induced polymerization of the acetylide anions and suggests the existence of the polyacenide fragment. Additionally, the process of polymerization is accompanied with a 10 7 fold enhancement of the electrical conductivity. The polymerization of acetylide anions demonstrates that high pressure compression is a viable route to synthesize novel metal polycarbides and materials with extended carbon networks, while shedding light on the synthesis of more complicated metal organics.

Reduction of iron-bearing lunar minerals for the production of oxygen

NASA Technical Reports Server (NTRS)

Massieon, Charles; Cutler, Andrew; Shadman, Farhang

1992-01-01

The kinetics and mechanism of the reduction of simulants of the iron-bearing lunar minerals olivine ((Fe,Mg)2SiO4), pyroxene ((Fe,Mg,Ca)SiO3), and ilmenite (FeTiO3) are investigated, extending previous work with ilmenite. Fayalite is reduced by H2 at 1070 K to 1480 K. A layer of mixed silica glass and iron forms around an unreacted core. Reaction kinetics are influenced by permeation of hydrogen through this layer and a reaction step involving dissociated hydrogen. Reaction mechanisms are independent of Mg content. Augite, hypersthene, and hedenbergite are reduced in H2 at the same temperatures. The products are iron metal and lower iron silicates mixed throughout the mineral. Activation energy rises with calcium content. Ilmenite and fayalite are reduced with carbon deposited on partially reduced minerals via the CO disproportionation reaction. Reduction with carbon is rapid, showing the carbothermal reduction of lunar minerals is possible.

Efficacy of desensitizing products containing 8% arginine and calcium carbonate for hypersensitivity relief in MIH-affected molars: an 8-week clinical study.

PubMed

Bekes, Katrin; Heinzelmann, Karolin; Lettner, Stefan; Schaller, Hans-Günter

2017-09-01

The objective of this study was to compare the efficacy in reducing hypersensitivity in molar incisor hypomineralization (MIH)-affected molars immediately and over 8 weeks combining a single in-office application and a homed-based program with desensitizing products containing 8% arginine and calcium carbonate. Nineteen children with at least one MIH-affected molar with hypersensitivity were included. Hypersensitivity was assessed with an evaporative (air) stimulus and a tactile stimulus. Each child received a single in-office treatment with a desensitizing paste containing 8% arginine and calcium carbonate (elmex Sensitive Professional desensitizing paste), followed by 8 weeks of brushing twice daily with a desensitizing toothpaste containing 8% arginine, calcium carbonate with 1450 ppm fluoride (elmex Sensitive Professional toothpaste), using the elmex Sensitive Professional toothbrush. Additionally, the corresponding mouthwash (elmex Sensitive Professional mouthwash) was used. Clinical assessments were made at baseline, immediately after the in-office treatment and after 1, 2, 4 and 8 weeks of brushing twice daily. Fifty-six molars with an air blast hypersensitivity score of 2 or 3 (Schiff Cold Air Sensitivity Scale) were included. Application of the desensitizing paste decreased hypersensitivity significantly immediately and throughout the 8 weeks recalls (p < 0.001). In conclusion, 8% arginine and calcium carbonate were able to reduce hypersensitivity successfully during this 8-week trial. Hypersensitivity is a major complaint in patients with MIH. This is the first study evaluating the desensitizing effect of a desensitizing paste containing 8% arginine and calcium carbonate in patients with MIH.

Mesozoic authigenic carbonate deposition in the Arctic: Do glendonites record gas hydrate destabilization during the Jurassic?

NASA Astrophysics Data System (ADS)

Morales, Chloe; Suan, Guillaume; Wierzbowski, Hubert; Rogov, Mikhail; Teichert, Barbara; Kienhuis, Michiel V. M.; Polerecky, Lubos; Middelburg, Jack B. M.; Reichart, Gert-Jan; van de Schootbrugge, Bas

2015-04-01

Glendonites are calcite pseudomorphs after ikaite, an unstable hydrated calcium carbonate mineral. Because present-day ikaite occurs predominantly in sub-polar environments and is unstable at warm temperatures, glendonites have been used as an indicator of near-freezing conditions throughout Earth history. Ikaite has also been observed in cold deep-sea environments like the Gulf of Mexico, the Japan Trench, and the Zaire Fan where their formation is possibly governed by other parameters. The description of glendonites in Paleocene-Eocene sediments of Svalbard, and Early Jurassic (Pliensbachian) deposits of northern Germany, however questions the role of temperature on ikaite precipitation (Spielhagen and Tripati, 2009; Teichert and Luppold, 2013). Anomalously low carbon isotope values of Jurassic glendonites point to the involvement of methane as a possible carbon source for ikaite/glendonite formation. Terrestrial organic matter degradation is also frequently evoked as a potential source of carbon. The involved bio- and geochemical processes remains thus not well constrained. Here we present new geochemical data of a large number of glendonites specimens from the Lower and Middle Jurassic of northern Siberia and the Lena river middle flows (Bajocian, Bathonian, Pliensbachian). Carbon and oxygen isotopic values show comparable trends between the different sections. Bulk glendonites δ13C and δ18O values vary from 0.0 to -44.5o and -15.0 to -0.8 respectively and show a negative correlation. Some samples display similar low δ13C values as the Pliensbachian glendonites of Germany (Teichert and Luppold, 2013), suggesting thermogenic and/or biogenic methane sources. The range of carbon isotope values is comparable to those observed at other methane seeps deposits. Further investigations are needed to better constrain the carbon cycle in these particular environmental conditions. The role of microbial communities into ikaite/glendonite formation equally needs to be considered. These results however caution the use of glendonites as a proxy for near-freezing conditions. References: Spielhagen, R.F., Tripati, A., 2009. Evidence from Svalbard for near-freezing temperatures and climate oscillations in the Arctic during the Paleocene and Eocene. Palaeogeography, Palaeoclimatology, Palaeoecology 278, 48-56. Teichert, B.M.A., Luppold, F.W., 2013. Glendonites from an Early Jurassic methane seep'Climate or methane indicators? Palaeogeography, Palaeoclimatology, Palaeoecology 390, 81-93.

Acidification of forest soil in Russia: From 1893 to present

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lapenis, A.G.; Lawrence, G.B.; Andreev, A.A.

2003-01-02

It is commonly believed that fine-textured soils developed on carbonate parent material are well buffered from possible acidification. There are no data, however, that document resistance of such soils to acidic deposition exposure on a timescale longer than 30-40 years. In this paper, we report on directly testing the long-term buffering capacity of nineteenth century forest soils developed on calcareous silt loam. In a chemical analysis comparing archived soils with modern soils collected from the same locations similar to 100 years later, we found varying degrees of forest-soil acidification in the taiga and forest steppe regions. Land-use history, increases inmore » precipitation, and acidic deposition were contributing factors in acidification. The acidification of forest soil was documented through decreases in soil pH and changes in concentrations of exchangeable calcium and aluminum, which corresponded with changes in communities of soil microfauna. Although acidification was found at all three analyzed locations, the trends in soil chemistry were most pronounced where the highest loading of acidic deposition had taken place.« less

Acidification of forest soil in Russia: From 1893 to present

USGS Publications Warehouse

Lapenis, A.G.; Lawrence, G.B.; Andreev, A.A.; Bobrov, A.A.; Torn, M.S.; Harden, J.W.

2004-01-01

It is commonly believed that fine-textured soils developed on carbonate parent material are well buffered from possible acidification. There are no data, however, that document resistance of such soils to acidic deposition exposure on a timescale longer than 30-40 years. In this paper, we report on directly testing the long-term buffering capacity of nineteenth century forest soils developed on calcareous silt loam. In a chemical analysis comparing archived soils with modern soils collected from the same locations ???100 years later, we found varying degrees of forest-soil acidification in the taiga and forest steppe regions. Land-use history, increases in precipitation, and acidic deposition were contributing factors in acidification. The acidification of forest soil was documented through decreases in soil pH and changes in concentrations of exchangeable calcium and aluminum, which corresponded with changes in communities of soil microfauna. Although acidification was found at all three analyzed locations, the trends in soil chemistry were most pronounced where the highest loading of acidic deposition had taken place. Copyright 2004 by the American Geophysical Union.

Current challenges and future directions for bacterial self-healing concrete.

PubMed

Lee, Yun Suk; Park, Woojun

2018-04-01

Microbially induced calcium carbonate precipitation (MICP) has been widely explored and applied in the field of environmental engineering over the last decade. Calcium carbonate is naturally precipitated as a byproduct of various microbial metabolic activities. This biological process was brought into practical use to restore construction materials, strengthen and remediate soil, and sequester carbon. MICP has also been extensively examined for applications in self-healing concrete. Biogenic crack repair helps mitigate the high maintenance costs of concrete in an eco-friendly manner. In this process, calcium carbonate precipitation (CCP)-capable bacteria and nutrients are embedded inside the concrete. These bacteria are expected to increase the durability of the concrete by precipitating calcium carbonate in situ to heal cracks that develop in the concrete. However, several challenges exist with respect to embedding such bacteria; harsh conditions in concrete matrices are unsuitable for bacterial life, including high alkalinity (pH up to 13), high temperatures during manufacturing processes, and limited oxygen supply. Additionally, many biological factors, including the optimum conditions for MICP, the molecular mechanisms involved in MICP, the specific microorganisms suitable for application in concrete, the survival characteristics of the microorganisms embedded in concrete, and the amount of MICP in concrete, remain unclear. In this paper, metabolic pathways that result in conditions favorable for calcium carbonate precipitation, current and potential applications in concrete, and the remaining biological challenges are reviewed.

Biomineralization in Newly Settled Recruits of the Scleractinian Coral Pocillopora damicornis

NASA Astrophysics Data System (ADS)

Meibom, A.; Gilis, M.; Domart-Coulon, I.; Grauby, O.; Stolarski, J.; Baronnet, A.

2014-12-01

Calcium carbonate biomineralization of scleractinian coral recruits is fundamental to the construction of reefs and their survival under stress from global and local environmental change. Establishing a baseline for how normal, healthy coral recruits initiate skeletal formation is therefore warranted. We present a multiscale, microscopic and spectroscopic investigation of skeletal elements deposited by Pocillopora damicornis recruits, from 12 h to 22 days after settlement in aquarium on a flat substrate. Six growth stages are defined, primarily based on appearance and morphology of successively deposited skeletal structures, with the following average formation timescales: A (<24 h), B (24-36 h), C (36-48 h), D (48- 72 h), E (72-96 h), and F (>10 days). Raman and energy dispersive X-ray spectroscopy indicate the presence of calcite among the earliest components of the basal plate, which consist of micrometer-sized, rod-shaped crystals with rhom- boidal habit. All later CaCO3 skeletal structures are composed exclusively of aragonite. High-resolution scanning electron microscopy reveals that, externally, all CaCO3 deposits consist of <100 nm granular units. Fusiform, dumbbell-like, and semispherulitic structures, 25-35 mm in longest dimension, occur only during the earliest stages (Stages A-C), with morphologies similar to structures formed abiotically or induced by organics in in vitro carbonate crystallization experiments. All other skeletal structures of the basal plate are composed of vertically extending lamellar bundles of granules. From Stage D, straight fibrils, 40-45 nm in width and presumably of organic composition, form bridges between these aragonitic bundles emerging from the growing front of fusing skeletal structures. Our results show a clear evolution in the coral polyp biomineralization process as the carbonate structures develop toward those characterizing the adult skeleton.

Biomineralization in newly settled recruits of the scleractinian coral Pocillopora damicornis.

PubMed

Gilis, Melany; Meibom, Anders; Domart-Coulon, Isabelle; Grauby, Olivier; Stolarski, Jarosław; Baronnet, Alain

2014-12-01

Calcium carbonate biomineralization of scleractinian coral recruits is fundamental to the construction of reefs and their survival under stress from global and local environmental change. Establishing a baseline for how normal, healthy coral recruits initiate skeletal formation is, therefore, warranted. Here, we present a thorough, multiscale, microscopic and spectroscopic investigation of skeletal elements deposited by Pocillopora damicornis recruits, from 12 h to 22 days after settlement in aquarium on a flat substrate. Six growth stages are defined, primarily based on appearance and morphology of successively deposited skeletal structures, with the following average formation time-scales: A (<24 h), B (24-36 h), C (36-48 h), D (48-72 h), E (72-96 h), and F (>10 days). Raman and energy dispersive X-ray spectroscopy indicate the presence of calcite among the earliest components of the basal plate, which consist of micrometer-sized, rod-shaped crystals with rhomboidal habit. All later CaCO3 skeletal structures are composed exclusively of aragonite. High-resolution scanning electron microscopy reveals that, externally, all CaCO3 deposits consist of <100 nm granular units. Fusiform, dumbbell-like, and semispherulitic structures, 25-35 µm in longest dimension, occur only during the earliest stages (Stages A-C), with morphologies similar to structures formed abiotically or induced by organics in in vitro carbonate crystallization experiments. All other skeletal structures of the basal plate are composed of vertically extending lamellar bundles of granules. From Stage D, straight fibrils, 40-45 nm in width and presumably of organic composition, form bridges between these aragonitic bundles emerging from the growing front of fusing skeletal structures. Our results show a clear evolution in the coral polyp biomineralization process as the carbonate structures develop toward those characterizing the adult skeleton. © 2014 Wiley Periodicals, Inc.

Effect of surface modification of nanofibres with glutamic acid peptide on calcium phosphate nucleation and osteogenic differentiation of marrow stromal cells.

PubMed

Karaman, Ozan; Kumar, Ankur; Moeinzadeh, Seyedsina; He, Xuezhong; Cui, Tong; Jabbari, Esmaiel

2016-02-01

Biomineralization is mediated by extracellular matrix (ECM) proteins with amino acid sequences rich in glutamic acid. The objective of this study was to investigate the effect of calcium phosphate deposition on aligned nanofibres surface-modified with a glutamic acid peptide on osteogenic differentiation of rat marrow stromal cells. Blend of EEGGC peptide (GLU) conjugated low molecular weight polylactide (PLA) and high molecular weight poly(lactide-co-glycolide) (PLGA) was electrospun to form aligned nanofibres (GLU-NF). The GLU-NF microsheets were incubated in a modified simulated body fluid for nucleation of calcium phosphate crystals on the fibre surface. To achieve a high calcium phosphate to fibre ratio, a layer-by-layer approach was used to improve diffusion of calcium and phosphate ions inside the microsheets. Based on dissipative particle dynamics simulation of PLGA/PLA-GLU fibres, > 80% of GLU peptide was localized to the fibre surface. Calcium phosphate to fibre ratios as high as 200%, between those of cancellous (160%) and cortical (310%) bone, was obtained with the layer-by-layer approach. The extent of osteogenic differentiation and mineralization of marrow stromal cells seeded on GLU-NF microsheets was directly related to the amount of calcium phosphate deposition on the fibres prior to cell seeding. Expression of osteogenic markers osteopontin, alkaline phosphatase (ALP), osteocalcin and type 1 collagen increased gradually with calcium phosphate deposition on GLU-NF microsheets. Results demonstrate that surface modification of aligned synthetic nanofibres with EEGGC peptide dramatically affects nucleation and growth of calcium phosphate crystals on the fibres leading to increased osteogenic differentiation of marrow stromal cells and mineralization. Copyright © 2013 John Wiley & Sons, Ltd.

The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: a comparison of serum, synovial fluid, albumin, EDTA, and water.

PubMed

Lewis, A C; Kilburn, M R; Heard, P J; Scott, T B; Hallam, K R; Allen, G C; Learmonth, I D

2006-08-01

Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition.

The mineral phase in the cuticles of two species of Crustacea consists of magnesium calcite, amorphous calcium carbonate, and amorphous calcium phosphate.

PubMed

Becker, Alexander; Ziegler, Andreas; Epple, Matthias

2005-05-21

The cuticules (shells) of the woodlice Porcellio scaber and Armadillidium vulgare were analysed with respect to their content of inorganic material. It was found that the cuticles consist of crystalline magnesium calcite, amorphous calcium carbonate (ACC), and amorphous calcium phosphate (ACP), besides small amounts of water and an organic matrix. It is concluded that the cuticle, which constitutes a mineralized protective organ, is chemically adapted to the biological requirements by this combination of different materials.

Automatic photometric titrations of calcium and magnesium in carbonate rocks

USGS Publications Warehouse

Shapiro, L.; Brannock, W.W.

1955-01-01

Rapid nonsubjective methods have been developed for the determination of calcium and magnesium in carbonate rocks. From a single solution of the sample, calcium is titrated directly, and magnesium is titrated after a rapid removal of R2O3 and precipitation of calcium as the tungstate. A concentrated and a dilute solution of disodium ethylenediamine tetraacetate are used as titrants. The concentrated solution is added almost to the end point, then the weak solution is added in an automatic titrator to determine the end point precisely.

Particulate matter analysis at elementary schools in Curitiba, Brazil.

PubMed

Avigo, Devanir; Godoi, Ana F L; Janissek, Paulo R; Makarovska, Yaroslava; Krata, Agnieszka; Potgieter-Vermaak, Sanja; Alfoldy, Balint; Van Grieken, René; Godoi, Ricardo H M

2008-06-01

The particulate matter indoors and outdoors of the classrooms at two schools in Curitiba, Brazil, was characterised in order to assess the indoor air quality. Information concerning the bulk composition was provided by energy-dispersive x-ray fluorescence (EDXRF). From the calculated indoor/outdoor ratios and the enrichment factors it was observed that S-, Cl- and Zn-rich particles are of concern in the indoor environment. In the present research, the chemical compositions of individual particles were quantitatively elucidated, including low-Z components like C, N and O, as well as higher-Z elements, using automated electron probe microanalysis low Z EPMA. Samples were further analysed for chemical and morphological aspects, determining the particle size distribution and classifying them according to elemental composition associations. Five classes were identified based on major elemental concentrations: aluminosilicate, soot, organic, calcium carbonate and iron-rich particles. The majority of the respirable particulate matter found inside of the classroom was composed of soot, biogenic and aluminosilicate particles. In view of the chemical composition and size distribution of the aerosol particles, local deposition efficiencies in the human respiratory system were calculated revealing the deposition of soot at alveolar level. The results showed that on average 42% of coarse particles are deposited at the extrathoracic level, whereas 24% are deposited at the pulmonary region. The fine fraction showed a deposition rate of approximately 18% for both deposition levels.

Breast Microcalcification Detection Using Super-Resolution Ultrasound Image Reconstruction

DTIC Science & Technology

2010-09-01

microcalcifications often occur as one of two types: calcium oxalate dihydrate or calcium hydroxyapatite. Their sizes range approximately from 0.1 mm to 0.5 mm...super-resolution imaging, ultrasound imaging, wave equation. 1. INTRODUCTION Microcalcifications, tiny specks of mineral deposits ( calcium ), are the

Distribution of Mitral Annular and Aortic Valve Calcium as Assessed by Unenhanced Multidetector Computed Tomography.

PubMed

Koshkelashvili, Nikoloz; Codolosa, Jose N; Goykhman, Igor; Romero-Corral, Abel; Pressman, Gregg S

2015-12-15

Aging is associated with calcium deposits in various cardiovascular structures, but patterns of calcium deposition, if any, are unknown. In search of such patterns, we performed quantitative assessment of mitral annular calcium (MAC) and aortic valve calcium (AVC) in a broad clinical sample. Templates were created from gated computed tomography (CT) scans depicting the aortic valve cusps and mitral annular segments in relation to surrounding structures. These were then applied to CT reconstructions from ungated, clinically indicated CT scans of 318 subjects, aged ≥65 years. Calcium location was assigned using the templates and quantified by the Agatston method. Mean age was 76 ± 7.3 years; 48% were men and 58% were white. Whites had higher prevalence (p = 0.03) and density of AVC than blacks (p = 0.02), and a trend toward increased MAC (p = 0.06). Prevalence of AVC was similar between men and women, but AVC scores were higher in men (p = 0.008); this difference was entirely accounted for by whites. Within the aortic valve, the left cusp was more frequently calcified than the others. MAC was most common in the posterior mitral annulus, especially its middle (P2) segment. For the anterior mitral annulus, the medial (A3) segment calcified most often. In conclusion, AVC is more common in whites than blacks, and more intense in men, but only in whites. Furthermore, calcium deposits in the mitral annulus and aortic valve favor certain locations. Copyright © 2015 Elsevier Inc. All rights reserved.

Proceedings of the Asilomar Conference on Polymers (9th) Held on February 9-12, 1986 at Asilomar, California.

DTIC Science & Technology

1986-06-01

reticulated vitreous carbon material r ~ y n uniformity anc. material distribution. The material s * -p~s~Oro prismatic specimens. Four specimens had...with carbon fiber, hydroxylapatite ceramic (HA), tri-calcium phosphate ceramic (TCP), various organic acids, and calcium sulphate, we have been able to...filamentous carbon device coated with an absorbable polymer to prevent * premature fragmentation of the carbon fiber. Fracture repair has been effected

Enzyme-accelerated and structure-guided crystallization of calcium carbonate: role of the carbonic anhydrase in the homologous system.

PubMed

Müller, Werner E G; Schlossmacher, Ute; Schröder, Heinz C; Lieberwirth, Ingo; Glasser, Gunnar; Korzhev, Michael; Neufurth, Meik; Wang, Xiaohong

2014-01-01

The calcareous spicules from sponges, e.g. from Sycon raphanus, are composed of almost pure calcium carbonate. In order to elucidate the formation of those structural skeletal elements, the function of the enzyme carbonic anhydrase (CA), isolated from this species, during the in vitro calcium carbonate-based spicule formation, was investigated. It is shown that the recombinant sponge CA substantially accelerates calcium carbonate formation in the in vitro diffusion assay. A stoichiometric calculation revealed that the turnover rate of the sponge CA during the calcification process amounts to 25 CO2s(-1) × molecule CA(-1). During this enzymatically driven process, initially pat-like particles are formed that are subsequently transformed to rhomboid/rhombohedroid crystals with a dimension of ~50 μm. The CA-catalyzed particles are smaller than those which are formed in the absence of the enzyme. The Martens hardness of the particles formed is ~4 GPa, a value which had been determined for other biogenic calcites. This conclusion is corroborated by energy-dispersive X-ray spectroscopy, which revealed that the particles synthesized are composed predominantly of the elements calcium, oxygen and carbon. Surprising was the finding, obtained by light and scanning electron microscopy, that the newly formed calcitic crystals associate with the calcareous spicules from S. raphanus in a highly ordered manner; the calcitic crystals almost perfectly arrange in an array orientation along the two opposing planes of the spicules, leaving the other two plane arrays uncovered. It is concluded that the CA is a key enzyme controlling the calcium carbonate biomineralization process, which directs the newly formed particles to existing calcareous spicular structures. It is expected that with the given tools new bioinspired materials can be fabricated. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Sedimentologic succession of uplifted coral community, Urvina Bay, Isabela Island, Galapagos Archipelago, Ecuador

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colgan, M.W.; Hollander, D.

1987-05-01

In March 1954, along the west-central coast of Isabela Island, an upward movement of magma suddenly raised Urvina Bay over 6 m and exposed several square kilometers of carbonate deposits covering a young aa lava flow (around 1000 years old). Results from 6 transect lines across the uplift, 30 cores, and 10 trenches describe the sedimentologic and ecologic transition from barren basalt to diverse carbonate sediments with small coral reefs. Along horizontal transects spanning from 0 to 7 m paleowater depth, there is a seaward progression from beaches, mangroves, and basalt to thick deposits (> 1.6 m) of carbonate sandsmore » and small coral reefs. Variation in water depth, degree of wave exposure, and irregularity of the aa lava topography provided many microhabitats where coral, calcareous algae, and mollusks settled and grew. Eight hermatypic coral species are found throughout the shelf, and three species (i.e., Pavona clavus, Pocillopora damicornis, and Porites lobata) produced five small, isolated, monospecific, coral-reef frameworks. The vertical section seen in cores and trenches shows that calcium carbonate increased upward, whereas volcanic sediments decreased; however, episodic layers occur with high concentrations of basaltic sands. In vertical samples from the central portion of the shelf, the coral population changed from small, isolated colonies of Psammocora (Plesioseris) superficalis near the basalt basement to large reef-forming colonies of Pocillopora damicornis farther upsection. Reefs of the Galapagos Islands are small and less diverse than most Pacific reefs. Nonetheless, understanding their temporal successional development should throw light on the origin and history of larger oceanic reefs in the Pacific.« less

Quantifying fat, oil, and grease deposit formation kinetics.

PubMed

Iasmin, Mahbuba; Dean, Lisa O; Ducoste, Joel J

2016-01-01

Fat, oil, and grease (FOG) deposits formed in sanitary sewers are calcium-based saponified solids that are responsible for a significant number of nationwide sanitary sewer overflows (SSOs) across United States. In the current study, the kinetics of lab-based saponified solids were determined to understand the kinetics of FOG deposit formation in sewers for two types of fat (Canola and Beef Tallow) and two types of calcium sources (calcium chloride and calcium sulfate) under three pH (7 ± 0.5, 10 ± 0.5, and ≈14) and two temperature conditions (22 ± 0.5 and 45 ± 0.5 °C). The results of this study displayed quick reactions of a fraction of fats with calcium ions to form calcium based saponified solids. Results further showed that increased palmitic fatty acid content in source fats, the magnitude of the pH, and temperature significantly affect the FOG deposit formation and saponification rates. The experimental data of the kinetics were compared with two empirical models: a) Cotte saponification model and b) Foubert crystallization model and a mass-action based mechanistic model that included alkali driven hydrolysis of triglycerides. Results showed that the mass action based mechanistic model was able to predict changes in the rate of formation of saponified solids under the different experimental conditions compared to both empirical models. The mass-action based saponification model also revealed that the hydrolysis of Beef Tallow was slower compared to liquid Canola fat resulting in smaller quantities of saponified solids. This mechanistic saponification model, with its ability to track the saponified solids chemical precursors, may provide an initial framework to predict the spatial formation of FOG deposits in municipal sewers using system wide sewer collection modeling software. Copyright © 2015 Elsevier Ltd. All rights reserved.

Magnetically responsive calcium carbonate microcrystals.

PubMed

Fakhrullin, Rawil F; Bikmullin, Aidar G; Nurgaliev, Danis K

2009-09-01

Here we report the fabrication of magnetically responsive calcium carbonate microcrystals produced by coprecipitation of calcium carbonate in the presence of citrate-stabilized iron oxide nanoparticles. We demonstrate that the calcite microcrystals obtained possess superparamagnetic properties due to incorporated magnetite nanoparticles and can be manipulated by an external magnetic field. The microcrystals doped with magnetic nanoparticles were utilized as templates for the fabrication of hollow polyelectrolyte microcapsules, which retain the magnetic properties of the sacrificial cores and might be spatially manipulated using a permanent magnet, thus providing the magnetic-field-facilitated delivery and separation of materials templated on magnetically responsive calcite microcrystals.

Amorphous and crystalline calcium carbonate distribution in the tergite cuticle of moulting Porcellio scaber (Isopoda, Crustacea).

PubMed

Neues, Frank; Hild, Sabine; Epple, Matthias; Marti, Othmar; Ziegler, Andreas

2011-07-01

The main mineral components of the isopod cuticle consists of crystalline magnesium calcite and amorphous calcium carbonate. During moulting isopods moult first the posterior and then the anterior half of the body. In terrestrial species calcium carbonate is subject to resorption, storage and recycling in order to retain significant fractions of the mineral during the moulting cycle. We used synchrotron X-ray powder diffraction, elemental analysis and Raman spectroscopy to quantify the ACC/calcite ratio, the mineral phase distribution and the composition within the anterior and posterior tergite cuticle during eight different stages of the moulting cycle of Porcellio scaber. The results show that most of the amorphous calcium carbonate (ACC) is resorbed from the cuticle, whereas calcite remains in the old cuticle and is shed during moulting. During premoult resorption of ACC from the posterior cuticle is accompanied by an increase within the anterior tergites, and mineralization of the new posterior cuticle by resorption of mineral from the anterior cuticle. This suggests that one reason for using ACC in cuticle mineralization is to facilitate resorption and recycling of cuticular calcium carbonate. Furthermore we show that ACC precedes the formation of calcite in distal layers of the tergite cuticle. Copyright © 2011 Elsevier Inc. All rights reserved.

Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

PubMed

Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

2016-01-20

Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution.

Fabrication of porous low crystalline calcite block by carbonation of calcium hydroxide compact.

PubMed

Matsuya, Shigeki; Lin, Xin; Udoh, Koh-ichi; Nakagawa, Masaharu; Shimogoryo, Ryoji; Terada, Yoshihiro; Ishikawa, Kunio

2007-07-01

Calcium carbonate (CaCO(3)) has been widely used as a bone substitute material because of its excellent tissue response and good resorbability. In this experimental study, we propose a new method obtaining porous CaCO(3) monolith for an artificial bone substitute. In the method, calcium hydroxide compacts were exposed to carbon dioxide saturated with water vapor at room temperature. Carbonation completed within 3 days and calcite was the only product. The mechanical strength of CaCO(3) monolith increased with carbonation period and molding pressure. Development of mechanical strength proceeded through two steps; the first rapid increase by bonding with calcite layer formed at the surface of calcium hydroxide particles and the latter increase by the full conversion of calcium hydroxide to calcite. The latter process was thought to be controlled by the diffusion of CO(2) through micropores in the surface calcite layer. Porosity of calcite blocks thus prepared had 36.8-48.1% depending on molding pressure between 1 MPa and 5 MPa. We concluded that the present method may be useful for the preparation of bone substitutes or the preparation of source material for bone substitutes since this method succeeded in fabricating a low-crystalline, and thus a highly reactive, porous calcite block.

Ground-water flow and water quality in northeastern Union County, Ohio

USGS Publications Warehouse

Wilson, K.S.

1987-01-01

A study was done by the U.S. Geological Survey, in cooperation with the Village of Richwood, Ohio, to determine directions of ground-water flow, ground-water-level fluctuations, and water quality in the northeastern part of Union County. The topography of the study area generally is featureless, and the land surfaces slopes gently eastward from 985 to 925 feet above sea level. Glacial deposits up to 48 feet thick cover the carbonate-bedrock aquifer. Three municipal wells and an adjoining abandoned landfill are located in an area previously excavated for clay deposits. An agricultural supply company is adjacent to the well field. Ground water flows from west to east with local variation to the northeast and southeast because of the influence of Fulton Creek. Richwood Lake occupies an abandoned sand-and-gravel quarry. Water-level fluctuations indicate that the and gravel deposits beneath the lake may be hydraulically connected to the bedrock aquifer. Water-quality data collected from 14 wells and Richwood Lake indicate that a hard to very hard calcium bicarbonate type water is characteristic of the study area. Dissolved solids ranged from 200 to 720 mg/L (Milligrams per liter) throughout the study area. Potassium ranged from 1.3 to 15 mg/L, with a median concentration of 2.0 mg/L. Concentration of 10 and 15 mg/L at one municipal well were five to eight times greater than the median concentration. Total organic carbon, ammonia, and organic nitrogen were present at every site. Concentrations of ammonia above 1 mg/L as nitrogen were found in water from two municipal wells and one domestic well. Total organic carbon was detected at a municipal well, a landfill well, and a domestic well at concentrations above 5 mg/L. Ground-water quality is similar throughout the study area except in the vicinity of the municipal well field, where water from one well had elevated concentrations of ammonia, dissolved manganese, dissolved chloride, dissolved, sodium, and total organic carbon.

Preparation and bioactive properties of nanocrystalline hydroxyapatite thin films obtained by conversion of atomic layer deposited calcium carbonate.

PubMed

Holopainen, Jani; Kauppinen, Kyösti; Mizohata, Kenichiro; Santala, Eero; Mikkola, Esa; Heikkilä, Mikko; Kokkonen, Hanna; Leskelä, Markku; Lehenkari, Petri; Tuukkanen, Juha; Ritala, Mikko

2014-09-01

Nanocrystalline hydroxyapatite thin films were fabricated on silicon and titanium by atomic layer deposition (ALD) of CaCO3 and its subsequent conversion to hydroxyapatite by diammonium hydrogen phosphate (DAP) solution. The effects of conversion process parameters to crystallinity and morphology of the films were examined. DAP concentration was found to be critical in controlling the crystal size and homogeneity of the films. The hydroxyapatite phase was identified by XRD. ToF-elastic recoil detection analysis studies revealed that the films are calcium deficient in relation to hydroxyapatite with a Ca/P ratio of 1.39 for films converted with 0.2 M DAP at 95 °C. The coatings prepared on titanium conformally follow the rough surface topography of the substrate, verifying that the good step coverage of the ALD method was maintained in the conversion process. The dissolution tests revealed that the coating was nondissolvable in the cell culture medium. Annealing the coated sample at 700 °C for 1 h seemed to enhance its bonding properties to the substrate. Also, the biocompatibility of the coatings was confirmed by human bone marrow derived cells in vitro. The developed method provides a new possibility to produce thin film coatings on titanium implants with bone-type hydroxyapatite that is biocompatible with human osteoblasts and osteoclasts.

Interlaboratory comparability, bias, and precision for four laboratories measuring analytes in wet deposition, October 1983-December 1984

USGS Publications Warehouse

Brooks, Myron H.; Schroder, LeRoy J.; Willoughby, Timothy C.

1987-01-01

Four laboratories involved in the routine analysis of wet-deposition samples participated in an interlaboratory comparison program managed by the U.S. Geological Survey. The four participants were: Illinois State Water Survey central analytical laboratory in Champaign, Illinois; U.S. Geological Survey national water-quality laboratories in Atlanta, Georgia, and Denver, Colorado; and Inland Waters Directorate national water-quality laboratory in Burlington, Ontario, Canada. Analyses of interlaboratory samples performed by the four laboratories from October 1983 through December 1984 were compared.Participating laboratories analyzed three types of interlaboratory samples--natural wet deposition, simulated wet deposition, and deionized water--for pH and specific conductance, and for dissolved calcium, magnesium, sodium, sodium, potassium, chloride, sulfate, nitrate, ammonium, and orthophosphate. Natural wet-deposition samples were aliquots of actual wet-deposition samples. Analyses of these samples by the four laboratories were compared using analysis of variance. Test results indicated that pH, calcium, nitrate, and ammonium results were not directly comparable among the four laboratories. Statistically significant differences between laboratory results probably only were meaningful for analyses of dissolved calcium. Simulated wet-deposition samples with known analyte concentrations were used to test each laboratory for analyte bias. Laboratory analyses of calcium, magnesium, sodium, potassium, chloride, sulfate, and nitrate were not significantly different from the known concentrations of these analytes when tested using analysis of variance. Deionized-water samples were used to test each laboratory for reporting of false positive values. The Illinois State Water Survey Laboratory reported the smallest percentage of false positive values for most analytes. Analyte precision was estimated for each laboratory from results of replicate measurements. In general, the Illinois State Water Survey laboratory achieved the greatest precision, whereas the U.S. Geological Survey laboratories achieved the least precision.

Effects of specific surface area of metallic nickel particles on carbon deposition kinetics

NASA Astrophysics Data System (ADS)

Chen, Zhi-yuan; Bian, Liu-zhen; Yu, Zi-you; Wang, Li-jun; Li, Fu-shen; Chou, Kuo-Chih

2018-02-01

Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I(D)/ I(G) of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.

Oxygen and carbon isotope disequilibria in Galapagos corals: isotopic thermometry and calcification physiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

McConnaughey, T.A.

1986-01-01

Biological carbonate skeletons are built largely from carbon dioxide, which reacts to form carbonate ion within thin extracellular solutions. The light isotopes of carbon and oxygen react faster than the heavy isotopes, depleting the resulting carbonate ions in /sup 13/C and /sup 18/O. Calcium carbonate precipitation occurs sufficiently fast that the skeleton remains out of isotopic equilibrium with surrounding fluids. This explanation for isotopic disequilibrium in biological carbonates was partially simulated in vitro, producing results similar to those seen in non-photosynthetic corals. Photosynthetic corals have higher /sup 13/C//sup 12/C ratios due to the preferential removal of /sup 12/C (as organicmore » carbon) from the reservoir of dissolved inorganic carbon. The oxygen isotopic variations in corals can be used to reconstruct past sea surface temperatures to an accuracy of about 0.5/sup 0/C. The carbon isotopic content of photosynthetic corals provides an indication of cloudiness. Using isotopic data from Galapagos corals, it was possible to construct proxy histories of the El Nino phenomenon. The physiology of skeletogenesis appears to be surprisingly similar in calcium carbonate, calcium phosphate, and silica precipitating systems.« less

Calcium and 1,25-dihydroxyvitamin D3 modulate genes of immune and inflammatory pathways in the human colon: a human crossover trial123

PubMed Central

Protiva, Petr; Pendyala, Swaroop; Nelson, Celeste; Augenlicht, Leonard H; Lipkin, Martin; Holt, Peter R

2016-01-01

Background: A high dietary calcium intake with adequate vitamin D status has been linked to lower colorectal cancer risk, but the mechanisms of these effects are poorly understood. Objective: The objective of this study was to elucidate the effects of a Western-style diet (WD) and supplemental calcium and/or 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on the colorectal mucosa. Design: We conducted 2 crossover trials to define molecular pathways in the human colorectum altered by 1) a 4-wk WD supplemented with and without 2 g calcium carbonate/d and 2) a 4-wk WD supplemented with 1,25(OH)2D3 (0.5 μg/d) with or without 2 g calcium carbonate/d. The primary study endpoint was genome-wide gene expression in biopsy specimens of the rectosigmoid colonic mucosa. Serum and urinary calcium concentrations were also measured. Results: Changes in urinary calcium accurately reflected calcium consumption. The WD induced modest upregulation of genes involved in inflammatory pathways, including interferon signaling, and calcium supplementation reversed these toward baseline. In contrast, supplementation of the WD with 1,25(OH)2D3 induced striking upregulation of genes involved in inflammation, immune response, extracellular matrix, and cell adhesion. Calcium supplementation largely abrogated these changes. Conclusions: Supplementing 1,25(OH)2D3 to a WD markedly upregulated genes in immune response and inflammation pathways, which were largely reversed by calcium supplementation. This study provides clinical trial evidence of global gene expression changes occurring in the human colorectum in response to calcium and 1,25(OH)2D3 intervention. One action of 1,25(OH)2D3 is to upregulate adaptive immunity. Calcium appears to modulate this effect, pointing to its biological interaction in the mucosa. This trial was registered at clinicaltrials.gov as NCT00298545. Trial protocol is available at http://clinicalstudies.rucares.org (protocol numbers PHO475 and PHO554). PMID:27009752

Bioactive Polymeric Nanoparticles for Periodontal Therapy

PubMed Central

Alfonso-Rodríguez, Camilo Andrés; Medina-Castillo, Antonio L.; Alaminos, Miguel; Toledano, Manuel

2016-01-01

Aims to design calcium and zinc-loaded bioactive and cytocompatible nanoparticles for the treatment of periodontal disease. Methods PolymP-nActive nanoparticles were zinc or calcium loaded. Biomimetic calcium phosphate precipitation on polymeric particles was assessed after 7 days immersion in simulated body fluid, by scanning electron microscopy attached to an energy dispersive analysis system. Amorphous mineral deposition was probed by X-ray diffraction. Cell viability analysis was performed using oral mucosa fibroblasts by: 1) quantifying the liberated deoxyribonucleic acid from dead cells, 2) detecting the amount of lactate dehydrogenase enzyme released by cells with damaged membranes, and 3) by examining the cytoplasmic esterase function and cell membranes integrity with a fluorescence-based method using the Live/Dead commercial kit. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests. Results Precipitation of calcium and phosphate on the nanoparticles surfaces was observed in calcium-loaded nanoparticles. Non-loaded nanoparticles were found to be non-toxic in all the assays, calcium and zinc-loaded particles presented a dose dependent but very low cytotoxic effect. Conclusions The ability of calcium-loaded nanoparticles to promote precipitation of calcium phosphate deposits, together with their observed non-toxicity may offer new strategies for periodontal disease treatment. PMID:27820866

Amorphous Calcium Carbonate Precipitation by Cellular Biomineralization in Mantle Cell Cultures of Pinctada fucata

PubMed Central

Xiang, Liang; Kong, Wei; Su, Jingtan; Liang, Jian; Zhang, Guiyou; Xie, Liping; Zhang, Rongqing

2014-01-01

The growth of molluscan shell crystals is generally thought to be initiated from the extrapallial fluid by matrix proteins, however, the cellular mechanisms of shell formation pathway remain unknown. Here, we first report amorphous calcium carbonate (ACC) precipitation by cellular biomineralization in primary mantle cell cultures of Pinctada fucata. Through real-time PCR and western blot analyses, we demonstrate that mantle cells retain the ability to synthesize and secrete ACCBP, Pif80 and nacrein in vitro. In addition, the cells also maintained high levels of alkaline phosphatase and carbonic anhydrase activity, enzymes responsible for shell formation. On the basis of polarized light microscopy and scanning electron microscopy, we observed intracellular crystals production by mantle cells in vitro. Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed the crystals to be ACC, and de novo biomineralization was confirmed by following the incorporation of Sr into calcium carbonate. Our results demonstrate the ability of mantle cells to perform fundamental biomineralization processes via amorphous calcium carbonate, and these cells may be directly involved in pearl oyster shell formation. PMID:25405357

Calcium bodies of Titanethes albus (Crustacea: Isopoda): molt-related structural dynamics and calcified matrix-associated bacteria.

PubMed

Vittori, Miloš; Kostanjšek, Rok; Znidaršič, Nada; Zagar, Kristina; Ceh, Miran; Strus, Jasna

2012-10-01

Crustaceans form a variety of calcium deposits in which they store calcium necessary for the mineralization of their exoskeletons. Calcium bodies, organs containing large amounts of calcium, have been reported in some terrestrial isopod crustaceans, but have not yet been extensively studied. We analyzed the architecture of these organs during the molt cycle in the isopod Titanethes albus. Two pairs of calcium bodies are positioned ventrolaterally in posterior pereonites of T. albus. Individual organs are epithelial sacs that contain material arranged in concentric layers delimited by thin laminae. As demonstrated by electron microscopy and fluorescence in situ hybridization, abundant bacteria are present within the calcium bodies. Regardless of the molt cycle stage, crystalline concretions are present in the central areas of the calcium bodies. Energy dispersive X-ray spectrometry of the concretions demonstrated that they are composed predominantly of calcium and phosphorus and selected area electron diffraction indicated the presence of hydroxyapatite. In molting animals, a glassy layer of mineralized matrix is formed between the envelope and the outermost lamina of the calcium body. This layer consists of an amorphous calcium mineral which contains less phosphorus than the central concretions and is resorbed after molt. Since changes in the mineralized matrix are synchronized with the molt cycle, the calcium bodies likely function as a storage compartment that complements sternal deposits as a source of calcium for the mineralization of the exoskeleton. Bacteria associated with the mineralized matrix of calcium bodies are evidently involved in calcium dynamics. Copyright © 2012 Elsevier Inc. All rights reserved.

Glaciomarine sedimentation and bottom current activity on the north-western and northern continental margins of Svalbard during the late Quaternary

NASA Astrophysics Data System (ADS)

Chauhan, Teena; Noormets, Riko; Rasmussen, Tine L.

2016-04-01

Palaeo-bottom current strength of the West Spitsbergen Current (WSC) and the influence of the Svalbard-Barents Sea Ice Sheet (SBIS) on the depositional environment along the northern Svalbard margins are poorly known. Two gravity cores from the southern Yermak Plateau and the upper slope north of Nordaustlandet, covering marine isotope stage (MIS) 1 to MIS 5, are investigated. Five lithofacies, based on grain size distribution, silt/clay ratio, content and mean of sortable silt (SS), are distinguished to characterise the contourite-dominated sedimentary environments. In addition, depositional environments are described using total organic carbon (TOC), total sulphur (TS) and calcium carbonate (CaCO3) contents of sediments. Facies A, containing coarse SS, suggests strong bottom current activity and good bottom water ventilation conditions as inferred from low TOC content. This facies was deposited during the glacial periods MIS 4, MIS 2 and during the late Holocene. Facies B is dominated by fine SS indicating weak bottom current and poor ventilation (cf. high TOC content of 1.2-1.6%), and correlates with the MIS 4/3 and MIS 2/1 transition periods. With an equal amount of clay and sand, fine SS and high content of TOC, facies C indicates reduced bottom current strength for intervals with sediment supply from proximal sources such as icebergs, sea ice or meltwater discharge. This facies was deposited during the last glacial maximum. Facies D represents mass-flow deposits on the northern Svalbard margin attributed to the SBIS advance at or near the shelf edge. Facies E sediments indicating moderate bottom current strength were deposited during MIS 5 and MIS 3, and during parts of MIS 2. This first late Quaternary proxy record of the WSC flow and sedimentation history from the northern Svalbard margin suggests that the oceanographic conditions and ice sheet processes have exerted first-order control on sediment properties.

21 CFR 582.80 - Trace minerals added to animal feeds.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Cobalt Cobalt acetate. Cobalt carbonate. Cobalt chloride. Cobalt oxide. Cobalt sulfate. Copper Copper... pyrophosphate. Copper sulfate. Iodine Calcium iodate. Calcium iodobehenate. Cuprous iodide. 3,5-Diiodosalicylic.... Thymol iodide. Iron Iron ammonium citrate. Iron carbonate. Iron chloride. Iron gluconate. Iron oxide...

21 CFR 582.80 - Trace minerals added to animal feeds.

Code of Federal Regulations, 2014 CFR

2014-04-01

... Cobalt Cobalt acetate. Cobalt carbonate. Cobalt chloride. Cobalt oxide. Cobalt sulfate. Copper Copper... pyrophosphate. Copper sulfate. Iodine Calcium iodate. Calcium iodobehenate. Cuprous iodide. 3,5-Diiodosalicylic.... Thymol iodide. Iron Iron ammonium citrate. Iron carbonate. Iron chloride. Iron gluconate. Iron oxide...

21 CFR 582.80 - Trace minerals added to animal feeds.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Cobalt Cobalt acetate. Cobalt carbonate. Cobalt chloride. Cobalt oxide. Cobalt sulfate. Copper Copper... pyrophosphate. Copper sulfate. Iodine Calcium iodate. Calcium iodobehenate. Cuprous iodide. 3,5-Diiodosalicylic.... Thymol iodide. Iron Iron ammonium citrate. Iron carbonate. Iron chloride. Iron gluconate. Iron oxide...

Biogas recirculation for simultaneous calcium removal and biogas purification within an expanded granular sludge bed system treating leachate.

PubMed

Luo, Jinghuan; Lu, Xueqin; Liu, Jianyong; Qian, Guangren; Lu, Yongsheng

2014-12-01

Biogas, generated from an expanded granular sludge bed (EGSB) reactor treating municipal solid waste (MSW) leachate, was recirculated for calcium removal from the leachate via a carbonation process with simultaneous biogas purification. Batch trials were performed to optimize the solution pH and imported biogas (CO2) for CaCO3 precipitation. With applicable pH of 10-11 obtained, continuous trials achieved final calcium concentrations of 181-375 mg/L (removal efficiencies≈92.8-96.5%) in the leachate and methane contents of 87.1-91.4% (purification efficiencies≈65.4-82.2%) in the biogas. Calcium-balance study indicates that 23-986 mg Ca/d was released from the bio-system under the carbonized condition where CaCO3 precipitating was moved outside the bioreactor, whereas 7918-9517 mg Ca/d was trapped into the system for the controlled one. These findings demonstrate that carbonation removal of calcium by biogas recirculation could be a promising alternative to pretreat calcium-rich MSW leachate and synergistically to improve methane content. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sedimentary patterns in perched spring travertines near Granada (Spain) as indicators of the paleohydrological and paleoclimatological evolution of a karst massif

NASA Astrophysics Data System (ADS)

Martín-Algarra, Agustín.; Martín-Martín, Manuel; Andreo, Bartolomé; Julià, Ramón; González-Gómez, Cecilio

2003-10-01

Perched spring travertines of the Granada basin (South Spain) constitute a perched system with four well-defined steps, which are formed by several facies associations deposited in different sub-environments (travertine pools, dams and cascades). These perched travertines are considered as a freshwater reef system with a facies zonation and stratigraphic architecture closely resembling that of marine reef terraces and prograding carbonate platforms. The travertine deposits have been dated by 230Th/ 234U and 14C methods. As in other Mediterranean areas, the travertine deposition occurred episodically during warm and wet interglacial periods coinciding with isotopic stages 9, 7 and 5, and with the transition between isotopic stages 2/1. During these periods, underground dissolution, large outflow in the springs and subsequent calcium carbonate precipitation occurred. In the same way that evolution of reef systems indicates sea level changes, the geomorphology, age and architecture of perched spring travertine systems may be used to interpret former climatically controlled changes in outflow, in base level marked by the altitude of springs and in the chemistry of spring waters. Thus, aggradation or climbing progradation may indicate an increase of outflow at the spring, progradation with toplap is due to a stable base level and, conversely, dowlapping progradation may signify that the base level was gradually dropping. Therefore, the travertines can be considered semiquantitative indicators of the paleohydrological evolution of karstic massifs and used as an important terrestrial proxy climate record.

21 CFR 184.1207 - Calcium lactate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... lactic acid with calcium carbonate or calcium hydroxide. (b) The ingredient meets the specifications of... manufacturing practice. (d) Prior sanctions for this ingredient different from the uses established in this...

21 CFR 184.1207 - Calcium lactate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... lactic acid with calcium carbonate or calcium hydroxide. (b) The ingredient meets the specifications of... manufacturing practice. (d) Prior sanctions for this ingredient different from the uses established in this...

21 CFR 184.1207 - Calcium lactate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... lactic acid with calcium carbonate or calcium hydroxide. (b) The ingredient meets the specifications of... manufacturing practice. (d) Prior sanctions for this ingredient different from the uses established in this...

Sevelamer is cost-saving vs. calcium carbonate in non-dialysis-dependent CKD patients in italy: a patient-level cost-effectiveness analysis of the INDEPENDENT study.

PubMed

Ruggeri, Matteo; Cipriani, Filippo; Bellasi, Antonio; Russo, Domenico; Di Iorio, Biagio

2014-01-01

To conduct a cost-effectiveness analysis of sevelamer versus calcium carbonate in patients with non-dialysis-dependent CKD (NDD-CKD) from the Italian NHS perspective using patient-level data from the INDEPENDENT-CKD study. Patient-level data on all-cause mortality, dialysis inception and phosphate binder dose were obtained for all 107 sevelamer and 105 calcium carbonate patients from the INDEPENDENT-CKD study. Hospitalization and frequency of dialysis data were collected post hoc for all patients via a retrospective chart review. Phosphate binder, hospitalization, and dialysis costs were expressed in 2012 euros using hospital pharmacy, Italian diagnosis-related group and ambulatory tariffs, respectively. Total life years (LYs) and costs per treatment group were calculated for the 3-year period of the study. Bootstrapping was used to estimate confidence intervals around outcomes, costs, and cost-effectiveness and to calculate the cost-effectiveness acceptability curve. A subgroup analysis of patients who did not initiate dialysis during the INDEPENDENT-CKD study was also conducted. Sevelamer was associated with 0.06 additional LYs (95% CI -0.04 to 0.16) and cost savings of EUR -5,615 (95% CI -10,066 to -1,164) per patient compared with calcium carbonate. On the basis of the bootstrap analysis, sevelamer was dominant compared to calcium carbonate in 87.1% of 10,000 bootstrap replicates. Similar results were observed in the subgroup analysis. RESULTS were driven by a significant reduction in all-cause mortality and significantly fewer hospitalizations in the sevelamer group, which offset the higher acquisition cost for sevelamer. Sevelamer provides more LYs and is less costly than calcium carbonate in patients with NDD-CKD in Italy.

Additive effects of acidification and mineralogy on calcium isotopes in Triassic/Jurassic boundary limestones

DOE PAGES

Jost, Adam B.; Bachan, Aviv; van de Schootbrugge, Bas; ...

2016-12-29

The end-Triassic mass extinction coincided with a negative δ 13 C excursion, consistent with release of 13C-depleted CO 2 from the Central Atlantic Magmatic Province. However, the amount of carbon released and its effects on ocean chemistry are poorly constrained. The co upled nature of the carbon and calcium cycles allows calcium isotopes to be used for constraining carbon cycle dynamics and vice versa. We present a high-resolution calcium isotope (δ 44/40 Ca) record from 100 m of marine limestone spanning the Triassic/Jurassic boundary in two stratigraphic sections from northern Italy. Immediately above the extinction horizon and the associated negativemore » excursion in δ 13 C, δ 44/40 Ca decreases by ca. 0.8‰ in 20 m of section and then recovers to preexcursion values. Coupled numerical models of the geological carbon and calcium cycles demonstrate that this δ 44/40 Ca excursion is too large to be explained by changes to seawater δ 44/40 Ca alone, regardless of CO 2 injection volume and duration. Less than 20% of the δ 44/40 Ca excursion can be attributed to acidification. The remaining 80% likely reflects a higher proportion of aragonite in the original sediment, based largely on high concentrations of Sr in the samples. Our study demonstrates that coupled models of the carbon and calcium cycles have the potential to help distinguish contributions of primary seawater isotopic changes from local or diagenetic effects on the δ 44/40 Ca of carbonate sediments. Finally, differentiating between these effects is critical for constraining the impact of ocean acidification during the end-Triassic mass extinction, as well as for interpreting other environmental events in the geologic past.« less

Additive effects of acidification and mineralogy on calcium isotopes in Triassic/Jurassic boundary limestones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jost, Adam B.; Bachan, Aviv; van de Schootbrugge, Bas

The end-Triassic mass extinction coincided with a negative δ 13 C excursion, consistent with release of 13C-depleted CO 2 from the Central Atlantic Magmatic Province. However, the amount of carbon released and its effects on ocean chemistry are poorly constrained. The co upled nature of the carbon and calcium cycles allows calcium isotopes to be used for constraining carbon cycle dynamics and vice versa. We present a high-resolution calcium isotope (δ 44/40 Ca) record from 100 m of marine limestone spanning the Triassic/Jurassic boundary in two stratigraphic sections from northern Italy. Immediately above the extinction horizon and the associated negativemore » excursion in δ 13 C, δ 44/40 Ca decreases by ca. 0.8‰ in 20 m of section and then recovers to preexcursion values. Coupled numerical models of the geological carbon and calcium cycles demonstrate that this δ 44/40 Ca excursion is too large to be explained by changes to seawater δ 44/40 Ca alone, regardless of CO 2 injection volume and duration. Less than 20% of the δ 44/40 Ca excursion can be attributed to acidification. The remaining 80% likely reflects a higher proportion of aragonite in the original sediment, based largely on high concentrations of Sr in the samples. Our study demonstrates that coupled models of the carbon and calcium cycles have the potential to help distinguish contributions of primary seawater isotopic changes from local or diagenetic effects on the δ 44/40 Ca of carbonate sediments. Finally, differentiating between these effects is critical for constraining the impact of ocean acidification during the end-Triassic mass extinction, as well as for interpreting other environmental events in the geologic past.« less

Influence of substrate mineralogy on bacterial mineralization of calcium carbonate: implications for stone conservation.

PubMed

Rodriguez-Navarro, Carlos; Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

2012-06-01

The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed.

Influence of Substrate Mineralogy on Bacterial Mineralization of Calcium Carbonate: Implications for Stone Conservation

PubMed Central

Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

2012-01-01

The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed. PMID:22447589

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, HyangKyu

The AMoRE (Advanced Mo based Rare process Experiment) collaboration is going to use calcium molybdate crystals to search for neutrinoless double beta decay of {sup 100}Mo isotope. In order to make the crystal, we use calcium carbonate and molybdenum oxide powders as raw materials. Therefore it is highly necessary to reduce potential sources for radioactive backgrounds such as U and Th in the powders. In this talk, we will present our studies for purification of calcium carbonate and molybdenum oxide powders.

Carbonate Precipitation through Microbial Activities in Natural Environment, and Their Potential in Biotechnology: A Review

PubMed Central

Zhu, Tingting; Dittrich, Maria

2016-01-01

Calcium carbonate represents a large portion of carbon reservoir and is used commercially for a variety of applications. Microbial carbonate precipitation, a by-product of microbial activities, plays an important metal coprecipitation and cementation role in natural systems. This natural process occurring in various geological settings can be mimicked and used for a number of biotechnologies, such as metal remediation, carbon sequestration, enhanced oil recovery, and construction restoration. In this study, different metabolic activities leading to calcium carbonate precipitation, their native environment, and potential applications and challenges are reviewed. PMID:26835451

New Advanced Technologies in Stem Cell Therapy

DTIC Science & Technology

2014-11-01

6-8 wks old utrophin/dystrophin double knockout (dKO) mice, a severe animal model of DMD, have an excess of ectopic fat , calcium deposits and...tissues in skeletal muscle alter the tissue environment and induce deregulation of muscle homeostasis; however, the cellular origin of muscle fat ...as a major contributor to ectopic fat cell, calcium deposits and fibrotic tissue formation within dystrophic muscle. In the current study, we propose

Characterization of Calcium Oxalates Generated as Biominerals in Cacti1

PubMed Central

Monje, Paula V.; Baran, Enrique J.

2002-01-01

The chemical composition and morphology of solid material isolated from various Cactaceae species have been analyzed. All of the tested specimens deposited high-purity calcium oxalate crystals in their succulent modified stems. These deposits occurred most frequently as round-shaped druses that sometimes coexist with abundant crystal sand in the tissue. The biominerals were identified either as CaC2O4.2H2O (weddellite) or as CaC2O4.H2O (whewellite). Seven different species from the Opuntioideae subfamily showed the presence of whewellite, and an equal number of species from the Cereoideae subfamily showed the deposition of weddellite. The chemical nature of these deposits was assessed by infrared spectroscopy. The crystal morphology of the crystals was visualized by both conventional light and scanning electron microscopy. Weddellite druses were made up of tetragonal crystallites, whereas those from whewellite were most often recognized by their acute points and general star-like shape. These studies clearly demonstrated that members from the main traditional subfamilies of the Cactaceae family could synthesize different chemical forms of calcium oxalate, suggesting a definite but different genetic control. The direct relationship established between a given Cactaceae species and a definite calcium oxalate biomineral seems to be a useful tool for plant identification and chemotaxonomy. PMID:11842173

Precision and bias of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1983; and January 1980 through September 1984

USGS Publications Warehouse

Schroder, L.J.; Bricker, A.W.; Willoughby, T.C.

1985-01-01

Blind-audit samples with known analyte concentrations have been prepared by the U.S. Geological Survey and distributed to the National Atmospheric Deposition Program 's Central Analytical Laboratory. The difference between the National Atmospheric Deposition Program and National Trends Network reported analyte concentrations and known analyte concentrations have been calculated, and the bias has been determined. Calcium, magnesium , sodium, and chloride were biased at the 99-percent confidence limit; potassium and sulfate were unbiased at the 99-percent confidence limit, for 1983 results. Relative-percent differences between the measured and known analyte concentration for calcium , magnesium, sodium, potassium, chloride, and sulfate have been calculated for 1983. The median relative percent difference for calcium was 17.0; magnesium was 6.4; sodium was 10.8; potassium was 6.4; chloride was 17.2; and sulfate was -5.3. These relative percent differences should be used to correct the 1983 data before user-analysis of the data. Variances have been calculated for calcium, magnesium, sodium, potassium, chloride, and sulfate determinations. These variances should be applicable to natural-sample analyte concentrations reported by the National Atmospheric Deposition Program and National Trends Network for calendar year 1983. (USGS)

Novel botanical drug DA-9803 prevents deficits in Alzheimer's mouse models.

PubMed

Pagnier, Guillaume J; Kastanenka, Ksenia V; Sohn, Miwon; Choi, Sangzin; Choi, Song-Hyen; Soh, HyeYeon; Bacskai, Brian J

2018-01-29

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by deposition of amyloid plaques and disruption of neural circuitry, leading to cognitive decline. Animal models of AD deposit senile plaques and exhibit structural and functional deficits in neurons and neural networks. An effective treatment would prevent or restore these deficits, including calcium dyshomeostasis observed with in-vivo imaging. We examined the effects of DA-9803, a multimodal botanical drug, in 5XFAD and APP/PS1 transgenic mice which underwent daily oral treatment with 30 or 100 mg/kg DA-9803 or vehicle alone. Behavioral testing and longitudinal imaging of amyloid deposits and intracellular calcium in neurons with multiphoton microscopy was performed. Chronic administration of DA-9803 restored behavioral deficits in 5XFAD mice and reduced amyloid-β levels. DA-9803 also prevented progressive amyloid plaque deposition in APP/PS1 mice. Elevated calcium, detected in a subset of neurons before the treatment, was restored and served as a functional indicator of treatment efficacy in addition to the behavioral readout. In contrast, mice treated with vehicle alone continued to progressively accumulate amyloid plaques and calcium overload. In summary, treatment with DA-9803 prevented structural and functional outcome measures in mouse models of AD. Thus, DA-9803 shows promise as a novel therapeutic approach for Alzheimer's disease.

Protective effect of Urtica dioica methanol extract against experimentally induced urinary calculi in rats.

PubMed

Zhang, Haiying; Li, Ning; Li, Kun; Li, Peng

2014-12-01

Renal calculi formation is one of the most common urological disorders. Urinary stone disease is a common disease, which affects 10‑12% of the population in industrialized countries. In males, the highest prevalence of the disease occurs between the age of 20 and 40 years, while in females, the highest incidence of the disease occurs later. Previous studies have shown that long‑term exposure to oxalate is toxic to renal epithelial cells and results in oxidative stress. In the present study, a methanolic extract of aerial parts of Urtica dioica was screened for antiurolithiatic activity against ethylene glycol and ammonium chloride‑induced calcium oxalate renal stones in male rats. In the control rats, ethylene glycol and ammonium chloride administration was observed to cause an increase in urinary calcium, oxalate and creatinine levels, as well as an increase in renal calcium and oxalate deposition. Histopathological observations revealed calcium oxalate microcrystal deposits in the kidney sections of the rats treated with ethylene glycol and ammonium chloride, indicating the induction of lithiasis. In the test rats, treatment with the methanolic extract of Urtica dioica was found to decrease the elevated levels of urinary calcium, oxalate and creatinine, and significantly decrease the renal deposition of calcium and oxalate. Furthermore, renal histological observations revealed a significant reduction in calcium oxalate crystal deposition in the test rats. Phytochemical analysis of the Urtica dioica extract was also performed using liquid chromatography‑electrospray ionization tandem mass spectrometry and high-performance liquid chromatography with photodiode array detection, to determine the chemical composition of the extract. The eight chemical constituents identified in the extract were protocatechuic acid, salicylic acid, luteolin, gossypetin, rutin, kaempferol‑3‑O‑rutinoside, kaempferol‑3‑O‑glucoside and chlorogenic acid. In conclusion, the results of the present study suggest that Urtica dioica has strong antiurolithiatic activity and may have potential as a natural therapeutic agent for various urological disorders.

Phosphate Removal and Recovery using Drinking Water Plant Waste Residuals - abstract

EPA Science Inventory

Phosphates adsorbed on calcium carbonate are environmental friendly, as they do not require further treatment for the phosphate species desorption due to its effectiveness as the plant fertilizer. In this study, an inexpensive calcium carbonate obtained as a waste material from d...

IR Spectroscopy and X-Ray Phase Analysis of the Chemical Composition of Gallstones

NASA Astrophysics Data System (ADS)

Pichugina, A. A.; Tsyro, L. V.; Unger, F. G.

2018-01-01

The composition of the inorganic and organic parts of gallstones was investigated by x-ray phase analysis and IR spectroscopy. Cholesterol, bilirubin, calcium bilirubinate, calcium carbonate, and calcium hydrogen phosphate are all found in gallstones. The major component is cholesterol. A gallstone was separated into layers and the inorganic part was separated out by annealing. Inorganic compounds were found to predominate in the outer layer of the gallstone, which is related to the mechanism of its formation. The inorganic part contains calcium carbonate, present in both the calcite and waterite modifications.

Results of the TTF-TCNQ- and the calcium carbonate-crystallization on the Long Duration Exposure Facility

NASA Technical Reports Server (NTRS)

Nielsen, Kjeld Flemming; Lind, M. David

1991-01-01

Experiment AO139A on the Long Duration Exposure Facility (LDEF) carried four large containers into orbit for five years with crystal growth solutions for lead sulfide, calcium carbonate, and tetra thiafulvalene- tetra cyanoquino methane (TTF-TCNQ). The LDEF was in excellent condition after the long orbital stay, and although the temperature data was lost, the experiment program had been working since the valves in all containers were opened. All four experiments produced crystals; however, they were of varying quality. The calcium carbonate crystals had the best appearance. The TTF-TCNQ crystals were packed together near the valve openings of the container. When taken apart, the single crystals showed some unusual morphological properties. X-ray investigations as well as conductivity measurements on the long duration space grown TTF-TCNQ crystals are presented, and pictures of the calcium carbonate are shown. Comparisons are made with previous space solution growth experiments on the European Spacelab Mission and the Apollo-Soyuz Test Project.

Method for in situ carbon deposition measurement for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Kuhn, J.; Kesler, O.

2014-01-01

Previous methods to measure carbon deposition in solid oxide fuel cell (SOFC) anodes do not permit simultaneous electrochemical measurements. Electrochemical measurements supplemented with carbon deposition quantities create the opportunity to further understand how carbon affects SOFC performance and electrochemical impedance spectra (EIS). In this work, a method for measuring carbon in situ, named here as the quantification of gasified carbon (QGC), was developed. TGA experiments showed that carbon with a 100 h residence time in the SOFC was >99.8% gasified. Comparison of carbon mass measurements between the TGA and QGC show good agreement. In situ measurements of carbon deposition in SOFCs at varying molar steam/carbon ratios were performed to further validate the QGC method, and suppression of carbon deposition with increasing steam concentration was observed, in agreement with previous studies. The technique can be used to investigate in situ carbon deposition and gasification behavior simultaneously with electrochemical measurements for a variety of fuels and operating conditions, such as determining conditions under which incipient carbon deposition is reversible.

Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation

PubMed Central

2011-01-01

Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4+ production during urea hydrolysis were incorporated in the model and captured critical changes in the major metal species. The electrical phase increases were potentially due to ion exchange processes that modified charge structure at mineral/water interfaces. Our study revealed the potential of geophysical monitoring for geochemical changes during urea hydrolysis and the advantages of combining multiple approaches to understand complex biogeochemical processes in the subsurface. PMID:21943229

Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

USGS Publications Warehouse

Lisle, John T.; Robbins, Lisa L.

2016-01-01

Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (<<1.0 nuclei cm−3 s−1) to instantaneous (8.60 × 1025 nuclei cm−3 s−1). The proposed model for homogenous nucleation of calcium carbonate in seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC) that is currently not accounted for in global carbon budgets and carbonate sediment diagenesis models.

Addition of a Fluoride-containing Radiopacifier Improves Micromechanical and Biological Characteristics of Modified Calcium Silicate Cements.

PubMed

Antonijevic, Djordje; Jeschke, Anke; Colovic, Bozana; Milovanovic, Petar; Jevremovic, Danimir; Kisic, Danilo; vom Scheidt, Annika; Hahn, Michael; Amling, Michael; Jokanovic, Vukoman; Busse, Björn; Djuric, Marija

2015-12-01

Calcium silicate cements (CSCs) with the addition of nanohydroxyapatite and calcium carbonate play a critical role in dental applications. To further improve their properties, particularly radiopacity and biointeractivity, the fluoride-containing radiopacifier ytterbium trifluoride (YbF3) was added to their composition, and biological and mechanical characteristics were evaluated. YbF3 was added to 3 different CSCs: cement I (CSC + calcium carbonate), cement II (CSC + nanohydroxyapatite), and Portland cement. Material characterization encompassed measurements of pH, calcium, ytterbium, and fluoride ion release; radiopacity; setting time; porosity; microindentation properties; wettability; and Fourier transform infrared spectroscopic, x-ray diffraction, and scanning electron microscopic analyses. Osteoblast- and osteoclast-like cells were grown on the materials' surface to evaluate their adherence. The addition of calcium carbonate, nanohydroxyapatite, and 30 wt% of YbF3 improved radiopacity and the setting time of experimental cements. The pH values did not differ among the groups. The greatest ytterbium and fluoride releases occurred in the Portland cement + YbF3 group. Combined x-ray diffraction and Fourier transform infrared spectroscopic analysis showed the presence of calcium hydroxide and calcium silicate hydrates. In addition, the presence of calcium ytterbium fluoride and ytterbium oxide proved that YbF3 reacted with cement compounds. Wettability of cement I + YbF3 was superior to other formulations, but its porosity and microindentation properties were weaker than in the Portland cement + YbF3 mixture. Cement II + YbF3 presented micromechanical indentation and porosity characteristics similar to the Portland-based cement formulation. Osteoclast- and osteoblast-like cells adhered to the cements' surfaces without alteration of the cell structural integrity. YbF3-containing CSCs with nanostructured hydroxyapatite and calcium carbonate are well suited for dental application. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Development of anti-scale poly(aspartic acid-citric acid) dual polymer systems for water treatment.

PubMed

Nayunigari, Mithil Kumar; Gupta, Sanjay Kumar; Kokkarachedu, Varaprasad; Kanny, K; Bux, F

2014-01-01

The formation of calcium sulphate and calcium carbonate scale poses major problems in heat exchangers and water cooling systems, thereby affecting the performance of these types of equipment. In order to inhibit these scale formations, new types of biodegradable water soluble single polymer and dual poly(aspartic acid-citric acid) polymers were developed and tested. The effectiveness of single polymer and four different compositions of poly aspartic acid and citric acid dual polymer systems as scale inhibitors were evaluated. Details of the synthesis, thermal stability, scale inhibition and the morphological characterization of single and dual polymers are presented in this scientific paper. It was found that the calcium sulphate scale inhibition rate was in the range 76.06-91.45%, while the calcium carbonate scale inhibition rate observed was in the range 23.37-30.0% at 65-70 °C. The finding suggests that the water soluble dual polymers are very effective in sulphate scale inhibition in comparison of calcium carbonate scale inhibition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Haiyan; Wang, Lijuan; Li, Kuo

Transformation between different types of carbon–carbon bonding in carbides often results in a dramatic change of physical and chemical properties. Under external pressure, unsaturated carbon atoms form new covalent bonds regardless of the electrostatic repulsion. It was predicted that calcium acetylide (also known as calcium carbide, CaC2) polymerizes to form calcium polyacetylide, calcium polyacenide and calcium graphenide under high pressure. In this work, the phase transitions of CaC2 under external pressure were systematically investigated, and the amorphous phase was studied in detail for the first time. Polycarbide anions like C 6 6- are identified with gas chromatography-mass spectrometry and severalmore » other techniques, which evidences the pressure induced polymerization of the acetylide anions and suggests the existence of the polyacenide fragment. Additionally, the process of polymerization is accompanied with a 107 fold enhancement of the electrical conductivity. The polymerization of acetylide anions demonstrates that high pressure compression is a viable route to synthesize novel metal polycarbides and materials with extended carbon networks, while shedding light on the synthesis of more complicated metal organics.« less

FTIR absorption reflection study of biomimetic growth of phosphates on titanium implants

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzębski, W.; Brożek, A.; Stoch, J.; Szaraniec, J.; Trybalska, B.; Kmita, G.

2000-11-01

Titanium has been used for many medical applications; however, its joining to a living bone still is not satisfactorily good, challenging appropriate investigations. The aim of this work was to generate chemical modifications at its surface such that in vivo conditions, heterogeneous nucleation, and then growth of apatite from the body fluid could be easily induced and successfully performed. For this purpose, on the titanium samples, the oxide sublayers containing titanium, calcium and silicon (TCS) were deposited from a suitable solution using the sol-gel deep-coating procedure. Dried samples were heated at 400°C then cooled and thermostatically held in synthetic body fluids (SBF, SBFIII) under physiological conditions to mimic the natural process of apatite formation. Changes in surface composition of TCS sublayers caused by the heating were studied with XPS. Infrared spectroscopy and scanning electron microscopy monitored successive steps of apatite growth. It was found that in SBF, at the precoated titanium surface, nucleation and growth of the apatite containing carbonate took place. In SBFIII, for a higher concentration of calcium ions in comparison with SBF, a much-enhanced growth of the apatite free of carbonate was observed. TCS precoatings applied on stainless steel and Cr-Co-Mo alloy (Micromed) act also as bioactive interfaces with high ability to nucleation of biologically equivalent apatite. Biomimetic formation of this apatite on biologically inactive materials can be an important step in implant surgery.