Sample records for calcium carbonate crystallization

  1. Controlling factors and mechanism of reactive crystallization of calcium carbonate polymorphs from calcium hydroxide suspensions

    Microsoft Academic Search

    Mitsutaka Kitamura; Haruo Konno; Atsunari Yasui; Hirokatsu Masuoka

    2002-01-01

    The crystallization was carried out by adding the Na2CO3 solution to the Ca(OH)2 suspension, and the controlling factor and the mechanism of the crystallization of calcium carbonate polymorphs were investigated. The reaction between calcium hydroxide and sodium carbonate proceeded almost with the stoichiometric ratio when the addition rate of Na2CO3 solution was low; however, at fast addition rate calcium hydroxide

  2. Hen eggwhite-mediated stack crystallization of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Hu, Yanli; Ma, Yongjun; Zhou, Yong; Nie, Fude; Duan, Xiaohui; Pei, Chonghua

    2010-03-01

    In this paper, the stack-like crystallization of calcium carbonate in the presence of hen eggwhite under direct drying and vacuum freeze drying was investigated, and marked morphological changes in the calcium carbonate particles were observed depending on the reaction condition used. Scanning electron microscopy (SEM), Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), and Nano Mechanical Tester were employed to characterize the samples. Results indicate that gelling eggwhite-mediated the formation of the "stack-like" layered calcium carbonate aggregates composed of considerable nanosheets under direct drying while only rhombohedra calcite crystal (1 0 4) was formed without any additives. An analogous structure to the brick-and-mortar arrangement was attainted by vacuum freeze drying. The average elastic modulus and the hardness of "stack-like" calcium carbonate hybrid material were assessed 0.9952 and 0.0415 GPa with Nano-indenter test, respectively.

  3. Alginate hydrogel-mediated crystallization of calcium carbonate

    SciTech Connect

    Ma, Yufei [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.c [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Haidian District, Beijing 100084 (China)

    2011-05-15

    We documented a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system for the purpose of understanding the mediating function of alginate on the crystallization of calcium carbonate. The alginate was involved in the nucleation and the growth process of CaCO{sub 3}. The crystal size, morphology and roughness of crystal surface were significantly influenced by the type of the alginate, which could be accounted for by the length of the G blocks in alginate. A combination of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that there were the chemical interactions between the alginate and the mineral phase. This strategic approach revealed the biologically controlled CaCO{sub 3} mineralization within calcium alginate hydrogels via the selective nucleation and the confined crystallization of CaCO{sub 3}. The results presented here could contribute to the understanding of the mineralization process in hydrogel systems. -- Graphical abstract: Schematic illustration of the growth of calcite aggregates with different morphologies obtained from (a) Low G alginate gels and (b) High G alginate gels. Display Omitted highlights: > We use a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system to understand the mediating function of alginate on the crystallization of CaCO{sub 3} crystals. > The crystal size, morphology and crystal surface roughness are influenced by the length of G blocks in alginate. There are chemical interactions between the alginate and the mineral phase. > We propose a potential mechanism of CaCO{sub 3} crystallization within High G and Low G calcium alginate hydrogel.

  4. Synthesis of calcium carbonate crystals by using bacteria

    Microsoft Academic Search

    Long Chen; Hui Zhang; Zhaopeng Qi; Wu Yao; Jing-Jian Wan; Ming Shao; Cun-Chao Zhang

    2012-01-01

    The synthesis of calcium carbonate (CaCO3) crystals in the presence of bacteria Escherichia coliform (E. coli) was investigated. The products were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray powder diffractometry. The results showed that, calcite spherical superstructures constructed from small rhombohedral building units were formed with bacteria, and the particles are much larger than those formed

  5. Hybrid Crystals of Calcium Carbonate and Amino Acids

    Microsoft Academic Search

    Ayako Kai; Toshikatsu Miki

    2000-01-01

    We have investigated the effects of amino acids on the crystallization of calcium carbonate (CaCO3), and the reactivity between amino acids and CaCO3. Noncharged-polar and acidic amino acids are highly incorporated into CaCO3 and stabilize cauliflower-like grains composed of vaterite which is thermodynamically unstable in the CaCO3 polymorphs. Amino acids in the hybrid CaCO3 form radicals different from those in

  6. Egg-white-mediated crystallization of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Zheng, Liang; Hu, Yanli; Ma, Yongjun; Zhou, Yong; Nie, Fude; Liu, Xun; Pei, Chonghua

    2012-12-01

    In this paper, shape-controlled crystallization and self-assembly of CaCO3 hierarchical architectures has been successfully synthesized via the gas diffusion method in egg white solution. Stepwise growth and assembly of CaCO3 nanoparticles has been observed from transition of an amorphous CaCO3 to the crystallization and stabilization of platelet-like nanoparticles and eventually, the wool sphere-like CaCO3 hierarchical architectures assembling of nanoparticles. The proteins binding on nanoparticle surfaces proved to regulate the growth of nanoparticles and subsequent assembly into hierarchical superstructures via electrostatic and dipole interactions. The samples were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and nano mechanical Tester. The measured average elastic modulus and the hardness of calcium carbonate hybrid materials were 5.32 GPa and 0.1886 GPa by the nano-indenter test, respectively.

  7. The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite.

    E-print Network

    Benning, Liane G.

    The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range controlled by the surface area of calcite. The second stage of the reaction is approximately 10 times slower

  8. Calcium Carbonate

    MedlinePLUS

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  9. Crystal Structure of Calcium-Deficient Carbonated Hydroxyapatite. Thermal Decomposition

    Microsoft Academic Search

    T. I. Ivanova; O. V. Frank-Kamenetskaya; A. B. Kol'tsov; V. L. Ugolkov

    2001-01-01

    Full Rietveld refinement of the crystal structure of the synthetic calcium-deficient carbonated apatite Ca13.40[Ca25.90 (NH4)0.10][(PO4)4.95(CO3)1.05(H2O)0.30][(OH)1.65(H2O)0.45] (space group P63\\/m; a=9.437(1), c=6.888(1) Å; Z=1; Rwp=5.23%) was carried out using X-ray powder diffraction data. The use of the model with the split position of O3 atom made it possible to find two orientations of CO3 triangles sharing one of their edges. They occupy

  10. A Novel Growth Process of Calcium Carbonate Crystals in Silk Fibroin Hydrogel System

    E-print Network

    Paris-Sud XI, Université de

    1 A Novel Growth Process of Calcium Carbonate Crystals in Silk Fibroin Hydrogel System Yufei Ma carbonate (CaCO3) crystal growth in the silk fibroin (SF) hydrogel with different concentrations by a simple ion diffusion method. The experimental results indicate that the CaCO3 crystals obtained from silk

  11. Modulating effect of acorn barnacle C-type lectins on the crystallization of calcium carbonate

    Microsoft Academic Search

    Hiroki Matsubara; Tamae Hayashi; Tomohisa Ogawa; Koji Muramoto; Mitsuru Jimbo; Hisao Kamiya

    2008-01-01

    The modulating effect of invertebrate C-type lectins on the crystallization of calcium carbonate was investigated. The multiple\\u000a C-type lectins, named BRA-1, ?2 and ?3, isolated from the acorn barnacle Megabalanus rosa inhibited the nucleation and growth of calcium carbonate cyrstals. Among BRA, BRA-2 most efficiently inhibited the crystal\\u000a nucleation of aragoite and calcite at the concentrations of >3.3 and >26

  12. Capillarity creates single-crystal calcite nanowires from amorphous calcium carbonate.

    PubMed

    Kim, Yi-Yeoun; Hetherington, Nicola B J; Noel, Elizabeth H; Kröger, Roland; Charnock, John M; Christenson, Hugo K; Meldrum, Fiona C

    2011-12-23

    Single-crystal calcite nanowires are formed by crystallization of morphologically equivalent amorphous calcium carbonate (ACC) particles within the pores of track etch membranes. The polyaspartic acid stabilized ACC is drawn into the membrane pores by capillary action, and the single-crystal nature of the nanowires is attributed to the limited contact of the intramembrane ACC particle with the bulk solution. The reaction environment then supports transformation to a single-crystal product. PMID:22069168

  13. 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. PMID:25681477

  14. Effect of silk sericin on morphology and structure of calcium carbonate crystal

    NASA Astrophysics Data System (ADS)

    Zhao, Rui-Bo; Han, Hua-Feng; Ding, Shao; Li, Ze-Hao; Kong, Xiang-Dong

    2013-06-01

    In this paper, silk sericin was employed to regulate the mineralization of calcium carbonate (CaCO3). CaCO3 composite particles were prepared by the precipitation reaction of sodium carbonate with calcium chloride solution in the presence of silk sericin. The as-prepared samples were collected at different reaction time to study the crystallization process of CaCO3 by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that silk sericin significantly affected the morphology and crystallographic polymorph of CaCO3. With increasing the reaction time, the crystal phase of CaCO3 transferred from calcite dominated to vaterite dominated mixtures, while the morphology of CaCO3 changed from disk-like calcite crystal to spherical vaterite crystal. These studies showed the potential of silk sericin used as a template molecule to control the growth of inorganic crystal.

  15. Calcium carbonate crystal growth beneath Langmuir monolayers of acidic ?-hairpin peptides.

    PubMed

    Gong, Haofei; Yang, Yi; Pluntke, Manuela; Marti, Othmar; Majer, Zsuzsa; Sewald, Norbert; Volkmer, Dirk

    2014-11-28

    Four amphiphilic peptides with designed hairpin structure were synthesized and their monolayers were employed as model systems to study biologically inspired calcium carbonate crystallization. Langmuir monolayers of hairpin peptides were investigated by surface pressure area isotherms, surface potential isotherms, Brewster angle microscopy (BAM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. A ?-hairpin conformation was found for all peptides at the air-water interface although their packing arrangements seem to be different. Crystallization of calcium carbonate under these peptide monolayers was investigated at different surface pressures and growth times both by in situ optical microscopy, BAM and ex situ investigations such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). An amorphous calcium carbonate precursor was found at the initial crystallization stage. The crystallization process occurred in three stages. It starts from the nucleation of amorphous particles being a kinetically controlled process. Crystal nuclei subsequently aggregate to large particles and vaterite crystals start to form inside the amorphous layer, with the monolayer fluidity exerting an important role. The third process includes the re-crystallization of vaterite to calcite, which is thermodynamically controlled by monolayer structural factors including the monolayer flexibility and packing arrangement of the polar headgroups. Thus, the kinetic factors, monolayer fluidity and flexibility as well as structure factors govern the crystal morphology and polymorph distribution simultaneously and synergistically. PMID:25292256

  16. The influence of polyaspartate additive on the growth and morphology of calcium carbonate crystals

    Microsoft Academic Search

    Laurie Anne Gower

    1997-01-01

    The addition of low levels of polyaspartate to a supersaturated calcium carbonate (CaCOsb3) solution leads to unusual morphologies in the inorganic phase. Spherulitic vaterite aggregates with helical protrusions, and distorted calcite crystals that contain spiral pits, have been produced. The helical particles are coated with an inorganic membrane that appears to be responsible for the helical twist. The polymer also

  17. 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.

  18. Dehydration and crystallization of amorphous calcium carbonate in solution and in air

    PubMed Central

    Ihli, Johannes; Wong, Wai Ching; Noel, Elizabeth H.; Kim, Yi-Yeoun; Kulak, Alexander N.; Christenson, Hugo K.; Duer, Melinda J.; Meldrum, Fiona C.

    2014-01-01

    The mechanisms by which amorphous intermediates transform into crystalline materials are poorly understood. Currently, attracting enormous interest is the crystallization of amorphous calcium carbonate, a key intermediary in synthetic, biological and environmental systems. Here we attempt to unify many contrasting and apparently contradictory studies by investigating this process in detail. We show that amorphous calcium carbonate can dehydrate before crystallizing, both in solution and in air, while thermal analyses and solid-state nuclear magnetic resonance measurements reveal that its water is present in distinct environments. Loss of the final water fraction—comprising less than 15% of the total—then triggers crystallization. The high activation energy of this step suggests that it occurs by partial dissolution/recrystallization, mediated by surface water, and the majority of the particle then crystallizes by a solid-state transformation. Such mechanisms are likely to be widespread in solid-state reactions and their characterization will facilitate greater control over these processes. PMID:24469266

  19. The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite

    Microsoft Academic Search

    Juan Diego Rodriguez-Blanco; Samuel Shaw; Liane G. Benning

    2011-01-01

    The kinetics and mechanisms of nanoparticulate amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range of environmentally relevant temperatures (7.5-25 °C) using synchrotron-based in situ time-resolved Energy Dispersive X-ray Diffraction (ED-XRD) in conjunction with high-resolution electron microscopy, ex situ X-ray diffraction and infrared spectroscopy. The crystallization process occurs in two stages; firstly, the particles of

  20. Effect of trace lanthanum ion on dissolution and crystal growth of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Kamiya, Natsumi; Kagi, Hiroyuki; Tsunomori, Fumiaki; Tsuno, Hiroshi; Notsu, Kenji

    2004-07-01

    Impurity effects of trace lanthanum ion (La 3+) on the dissolution and growth of calcium carbonate were studied with in situ observation techniques. Dissolution kinetics of two polymorphs of calcium carbonate, calcite and vaterite, were investigated by monitoring the pH in the solution with laser-induced fluorescence spectroscopy using a pH-sensitive reagent, seminaphthorhodafluors. No effect on dissolution of vaterite was observed with the spectroscopic observations, whereas calcite dissolution was significantly inhibited by lanthanum ion with concentrations higher than 1 ?M. Crystal growth and dissolution processes of calcite under the lanthanum-doped condition were observed by means of atomic force microscopy. Step propagations during crystal growth and dissolution of calcite were inhibited by trace lanthanum ion (5 ?M). An insoluble thin layer of lanthanum carbonate deposited on the step site of the calcite surface could be a possible cause of the inhibitions observed both for dissolution and growth.

  1. Early homogenous amorphous precursor stages of calcium carbonate and subsequent crystal growth in levitated droplets.

    PubMed

    Wolf, Stephan E; Leiterer, Jork; Kappl, Michael; Emmerling, Franziska; Tremel, Wolfgang

    2008-09-17

    An in situ study of the contact-free crystallization of calcium carbonate in acoustic levitated droplets is reported. The levitated droplet technique allows an in situ monitoring of the crystallization while avoiding any foreign phase boundaries that may influence the precipitation process by heterogeneous nucleation. The diffusion-controlled precipitation of CaCO3 at neutral pH starts in the initial step with the homogeneous formation of a stable, nanosized liquid-like amorphous calcium carbonate phase that undergoes in a subsequent step a solution-assisted transformation to calcite. Cryogenic scanning electron microscopy studies indicate that precipitation is not induced at the solution/air interface. Our findings demonstrate that a liquid-liquid phase separation occurs at the outset of the precipitation under diffusion-controlled conditions (typical for biomineral formation) with a slow increase of the supersaturation at neutral pH. PMID:18717561

  2. Calcium carbonate crystallization on xiphoid of the cuttlefish

    NASA Astrophysics Data System (ADS)

    Manoli, F.; Dalas, E.

    2000-08-01

    A mollusc shell, the xiphoid from cuttlefish was found to be a substrate favouring the deposition of aragonite crystals from stable supersaturated solutions at pH 8.50 and 25°C. The crystallization was studied at constant solution composition, thus making it possible for a relatively large amount of the overgrowths to be formed and to be identified exclusively as aragonite crystals. The apparent order found from kinetics data was n=4.1±0.4, thus suggesting a polynuclear mechanism. A surface energy of 24±3 mJ m -2 was calculated for the growing phase and a four-ion cluster forming the critical nucleus, according to the classical nucleation theory.

  3. Calcium Carbonate Storage in Amorphous Form and Its Template-Induced Crystallization

    SciTech Connect

    Han, T Y; Aizenberg, J

    2007-08-31

    Calcium carbonate crystallization in organisms often occurs through the transformation from the amorphous precursor. It is believed that the amorphous phase could be temporarily stabilized and stored, until its templated transition to the crystalline form is induced. Here we develop a bio-inspired crystallization strategy that is based on the above mechanism. Amorphous calcium carbonate (ACC) spherulitic particles are formed and stabilized on a self-assembled monolayer (SAM) of hydroxy-terminated alkanethiols on Au surface. The ACC is stored as a reservoir for ions and is induced to crystallize on command by introducing a secondary surface that is functionalized with carboxylic acid-terminated SAM. This secondary surface acts as a template for oriented and patterned nucleation. Various oriented crystalline arrays and micropatterned films are formed. We also show that the ACC phase can be doped with foreign ions (e.g. Mg) and organic molecules (e.g. dyes) and that these dopants later function as growth modifiers of calcite crystals and become incorporated into the crystals during the transformation process of ACC to calcite. We believe that our strategy opens the way of using a stabilized amorphous phase as a versatile reservoir system that can be converted in a highly controlled fashion to a crystalline form upon contacting the nucleating template.

  4. Calcium carbonate overdose

    MedlinePLUS

    Tums overdose; Calcium overdose ... Calcium ... Products containing calcium carbonate, including Certain antacids (Tums, Chooz) Certain mineral supplements Certain hand lotions Certain vitamin and mineral supplements Note: ...

  5. Transformation and crystallization energetics of synthetic and biogenic amorphous calcium carbonate

    PubMed Central

    Radha, A. V.; Forbes, Tori Z.; Killian, Christopher E.; Gilbert, P. U. P. A.; Navrotsky, Alexandra

    2010-01-01

    Amorphous calcium carbonate (ACC) is a metastable phase often observed during low temperature inorganic synthesis and biomineralization. ACC transforms with aging or heating into a less hydrated form, and with time crystallizes to calcite or aragonite. The energetics of transformation and crystallization of synthetic and biogenic (extracted from California purple sea urchin larval spicules, Strongylocentrotus purpuratus) ACC were studied using isothermal acid solution calorimetry and differential scanning calorimetry. Transformation and crystallization of ACC can follow an energetically downhill sequence: more metastable hydrated ACC ? less metastable hydrated ACC?anhydrous ACC ? biogenic anhydrous ACC?vaterite ? aragonite ? calcite. In a given reaction sequence, not all these phases need to occur. The transformations involve a series of ordering, dehydration, and crystallization processes, each lowering the enthalpy (and free energy) of the system, with crystallization of the dehydrated amorphous material lowering the enthalpy the most. ACC is much more metastable with respect to calcite than the crystalline polymorphs vaterite or aragonite. The anhydrous ACC is less metastable than the hydrated, implying that the structural reorganization during dehydration is exothermic and irreversible. Dehydrated synthetic and anhydrous biogenic ACC are similar in enthalpy. The transformation sequence observed in biomineralization could be mainly energetically driven; the first phase deposited is hydrated ACC, which then converts to anhydrous ACC, and finally crystallizes to calcite. The initial formation of ACC may be a first step in the precipitation of calcite under a wide variety of conditions, including geological CO2 sequestration. PMID:20810918

  6. Crystallization and assembling behavior of calcium carbonate controlled by Ca-organic fibers

    NASA Astrophysics Data System (ADS)

    Chen, Anliang; Ma, Peiyan; Fu, Zhengyi; Wu, Yan; Kong, Wei

    2013-08-01

    Calcium carbonate (CaCO3) crystals with different phases were obtained on the basis of one-dimensional Ca-deoxycholate fibers (Ca-DC fibers) under ambient conditions. Ca-DC fibers were prepared by the combination of Ca2+ ions and sodium deoxycholate (SDC) before the addition of sodium bicarbonate. Vaterite dominated mixtures could be easily obtained in the presence of Ca-DC fibers in the aqueous system at 10 °C. As the temperature was increased to 30 and 120 °C, pure vaterite and aragonite with novel morphologies were obtained, respectively. The framework formed by one-dimensional Ca-DC fibers was demonstrated to be the key role in mediating the crystallization and assembling behaviors of calcium carbonate. In this study, Ca-DC fibers, prepared as a novel insoluble organic polymorph controller, could even play an important role in the industrial production of CaCO3 with different polymorphs in future and other similar Ca-organic fibers are believed to have same functions as well.

  7. Liquid-liquid separation explains "non-classical" behavior during calcium carbonate crystallization

    NASA Astrophysics Data System (ADS)

    Wallace, A. F.; Banfield, J. F.; De Yoreo, J.

    2012-12-01

    Recent experimental characterizations of the early stages of calcium carbonate crystallization reveal an abundance of nanometer-sized so-called "pre-nucleation" clusters that appear prior to the formation of an amorphous intermediate phase. The prevailing interpretation of the clusters as thermodynamically stable species is incompatible with classical nucleation theories that predict formation of unstable clusters within supersaturated solutions, as well as long-standing speciation models with demonstrated predictive capability over a wide range of conditions. Using molecular dynamics simulations, this study demonstrates that a liquid-liquid phase separation occurs within the range of concentrations utilized by experimental investigations. The ion-rich dense liquid phase (DLP) persists in metastable equilibrium with a dilute solution phase until coalescence and solidification of the DLP droplets results in formation of amorphous calcium carbonate (ACC). The demonstrated precursor relationship of the DLP to ACC suggests that experimental observations can be reconciled within the context of classical phase separation models without invoking non-classical constructs such as stable pre-nucleation clusters.

  8. 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.

  9. Effect of Dispersion Condition of Calcium Carbonate on the Crystallization and Melting Behavior of Polypropylene\\/CaCO3 Nanocomposites

    Microsoft Academic Search

    Ran Tao; Zheng Ying Liu; Wei Yang; Ming bo Yang

    2008-01-01

    Polypropylene\\/calcium carbonate (PP\\/CaCO3) nanocomposites were prepared by melt compounding (C-1) and novel compounding process (C-2), respectively. Scanning electronic microscope (SEM) results illustrated that CaCO3 nanoparticles were well dispersed at nanoscale in C-2, whereas the nanoparticles were mostly aggregate in C-1. Differential scanning calorimetry (DSC) measurements indicated the onset crystallization temperature was increased by 11.4°C and the supercooling wasdecreased by 13.68°C

  10. Chitosan-calcium carbonate composites by a biomimetic process

    Microsoft Academic Search

    Sukun Zhang; K. E. Gonsalves

    1995-01-01

    The crystal growth of calcium carbonate on a chitosan substrate was achieved using a supersaturated calcium carbonate solution, by using various additives, such as 6-aminocaproic acid (6AA) and polyacrylic acid (PAA). Polyacrylic acid modified the chitosan-film surface and promoted the nucleation of calcium carbonate crystals. In the absence of polyacrylic acid, sporadic nucleation and crystallization was observed via optical microscopy.

  11. Intrinsically Disordered and Pliable Starmaker-Like Protein from Medaka (Oryzias latipes) Controls the Formation of Calcium Carbonate Crystals

    PubMed Central

    Ró?ycka, Miros?awa; Wojtas, Magdalena; Jakób, Micha?; Stigloher, Christian; Grzeszkowiak, Miko?aj; Mazur, Maciej; O?yhar, Andrzej

    2014-01-01

    Fish otoliths, biominerals composed of calcium carbonate with a small amount of organic matrix, are involved in the functioning of the inner ear. Starmaker (Stm) from zebrafish (Danio rerio) was the first protein found to be capable of controlling the formation of otoliths. Recently, a gene was identified encoding the Starmaker-like (Stm-l) protein from medaka (Oryzias latipes), a putative homologue of Stm and human dentine sialophosphoprotein. Although there is no sequence similarity between Stm-l and Stm, Stm-l was suggested to be involved in the biomineralization of otoliths, as had been observed for Stm even before. The molecular properties and functioning of Stm-l as a putative regulatory protein in otolith formation have not been characterized yet. A comprehensive biochemical and biophysical analysis of recombinant Stm-l, along with in silico examinations, indicated that Stm-l exhibits properties of a coil-like intrinsically disordered protein. Stm-l possesses an elongated and pliable structure that is able to adopt a more ordered and rigid conformation under the influence of different factors. An in vitro assay of the biomineralization activity of Stm-l indicated that Stm-l affected the size, shape and number of calcium carbonate crystals. The functional significance of intrinsically disordered properties of Stm-l and the possible role of this protein in controlling the formation of calcium carbonate crystals is discussed. PMID:25490041

  12. Effects of Additives and Templates on Calcium Carbonate Mineralization in vitro

    E-print Network

    Paris-Sud XI, Université de

    Accepted M anuscript Effects of Additives and Templates on Calcium Carbonate Mineralization controlling the calcium carbonate crystals formation and the complexity of the crystal morphologies in vitro organic matrices mediate calcium carbonate mineralization. Keywords: additive; template; in vitro

  13. ORIGINAL PAPER Calcium Carbonate Nucleation in an Alkaline Lake

    E-print Network

    ORIGINAL PAPER Calcium Carbonate Nucleation in an Alkaline Lake Surface Water, Pyramid Lake, Nevada (X) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water-011-9150-3 #12;Keywords Pyramid Lake, Nevada, USA Á Calcium carbonate Á Nucleation Á Calcium carbonate nucleation

  14. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...As a byproduct in the “Lime soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of calcium carbonate from calcium chloride in the “Calcium...

  15. Calcium carbonate with magnesium overdose

    MedlinePLUS

    The combination of calcium carbonate and magnesium is commonly found in antacids, which are medicines that provide heartburn relief. Calcium carbonate with magnesium overdose occurs when someone accidentally or ...

  16. Cell wall sheath surrounding calcium oxalate crystals in mulberry idioblasts

    Microsoft Academic Search

    H. Katayama; Y. Fujibayashi; S. Nagaoka; Y. Sugimura

    2007-01-01

    Summary.  The distribution and ultrastructural features of idioblasts containing calcium oxalate crystals were studied in leaf tissues\\u000a of mulberry, Morus alba L. In addition to the calcium carbonate crystals formed in epidermal idioblasts, large calcium oxalate crystals were deposited\\u000a in cells adjacent to the veins and surrounded by a cell wall sheath which had immunoreactivity with an antibody recognizing\\u000a a xyloglucan

  17. Crystal growth of calcium carbonate on the cellulose acetate/pyrrolidon blend films in the presence of L-aspartic acid

    NASA Astrophysics Data System (ADS)

    Zhang, Xiuzhen; Xie, Anjian; Huang, Fangzhi; Shen, Yuhua

    2014-03-01

    The morphogenesis and growth process of calcium carbonate on the cellulose acetate/polyvinyl pyrrolidone (CA/PVP) blend films in the presence of L-aspartic acid was carefully investigated. The results showed that the concentration of L-aspartic acid, the initial pH value of reaction solution and temperature turned out to be important factors for the control of morphologies and polymorphs of calcium carbonate. Complex morphologies of CaCO3 particles, such as cubes, rose-like spheres, twinborn-spheres, cone-like, bouquet-like, etc. could be obtained under the different experimental conditions. The dynamic process of formation of rose-like sphere crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. This research may provide a promising method to prepare other inorganic materials with complex morphologies.

  18. Biosynthesis of L-ascorbic acid and conversion of carbons 1 and 2 of L-ascorbic acid to oxalic acid occurs within individual calcium oxalate crystal idioblasts.

    PubMed

    Kostman, T A; Tarlyn, N M; Loewus, F A; Franceschi, V R

    2001-02-01

    L-Ascorbic acid (AsA) and its metabolic precursors give rise to oxalic acid (OxA) found in calcium oxalate crystals in specialized crystal idioblast cells in plants; however, it is not known if AsA and OxA are synthesized within the crystal idioblast cell or transported in from surrounding mesophyll cells. Isolated developing crystal idioblasts from Pistia stratiotes were used to study the pathway of OxA biosynthesis and to determine if idioblasts contain the entire path and are essentially independent in OxA synthesis. Idioblasts were supplied with various (14)C-labeled compounds and examined by micro-autoradiography for incorporation of (14)C into calcium oxalate crystals. [(14)C]OxA gave heavy labeling of crystals, indicating the isolated idioblasts are functional in crystal formation. Incubation with [1-(14)C]AsA also gave heavy labeling of crystals, whereas [6-(14)C]AsA gave no labeling. Labeled precursors of AsA (L-[1-(14)C]galactose; D-[1-(14)C]mannose) also resulted in crystal labeling, as did the ascorbic acid analog, D-[1-(14)C]erythorbic acid. Intensity of labeling of isolated idioblasts followed the pattern OxA > AsA (erythorbic acid) > L-galactose > D-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via D-mannose and L-galactose is operational in individual P. stratiotes crystal idioblasts. These results are discussed with respect to fine control of calcium oxalate precipitation and the concept of crystal idioblasts as independent physiological compartments. PMID:11161021

  19. 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.

  20. Crystal size distributions of induced calcium carbonate crystals in polyaspartic acid and Mytilus edulis acidic organic proteins aqueous solutions

    NASA Astrophysics Data System (ADS)

    Roqué, Josep; Molera, Judit; Vendrell-Saz, Màrius; Salvadó, Nativitat

    2004-02-01

    Different concentrations of soluble matrix extracts from Mytilus edulis and polyaspartic acid were mixed with CaCl 2 aqueous solutions to produce CaCO 3 crystallizations under controlled conditions. The obtained crystals were observed at several intervals of time by optical microscopy and scanning electron microscopy (SEM). Image treatment of the SEM images allowed quantifying the crystal size distribution (CSD) in different crystallization conditions. CSD graphics showed that polyaspartic acid induced nucleation and inhibited crystal growth, and soluble matrix extracts from Mytilus edulis induced nucleation, but its inhibition rate of crystal growth is less than polyaspartic. Soluble matrix extracts from Mytilus edulis showed an equilibrium between nucleation and crystal growth. Also, XRD patterns have been acquired in order to determine the crystalline phases obtained by inducing crystallization (calcite and vaterite). Vaterite polymorph appeared in all induced crystallization events, but not in blank aqueous solutions.

  1. Promotion and Inhibition of Calcium Carbonate Crystallization In Vitro by Matrix Protein From Blue Crab Exoskeleton

    Microsoft Academic Search

    M. E. GUNTHORPE; C. S. SIKES; A. P. WHEELER

    1990-01-01

    Soluble organic matrix isolated from dorsal carapaces of the blue crab, Callinectes sapidus, inhibited CaC03 crystallization when free in solution. Immobilized matrix complexes, prepared by crosslinking soluble matrix to decalcified crab carapace, promoted CaC03 formation in that crystallization in the presence of the immobilized soluble matrix complexes began sooner than in solution controls. In the experimental treatments, deposition of crystals

  2. Calcium Carbonate Polyamorphism and Its Role in Biomineralization: How Many Amorphous Calcium Carbonates Are There?

    E-print Network

    Cartwright, Julyan H E; Gale, Julian D; Gebauer, Denis; Sainz-Díaz, C Ignacio; 10.1002/anie.201203125

    2012-01-01

    Although the polymorphism of calcium carbonate is well known, and its polymorphs-calcite, aragonite, and vaterite-have been highly studied in the context of biomineralization, polyamorphism is a much more recently discovered phenomenon, and the existence of more than one amorphous phase of calcium carbonate in biominerals has only very recently been understood. Here we summarize what is known about polyamorphism in calcium carbonate as well as what is under- stood about the role of amorphous calcium carbonate in biominerals. We show that consideration of the amorphous forms of calcium carbonate within the physical notion of polyamorphism leads to new insights when it comes to the mechanisms by which polymorphic structures can evolve in the first place. This not only has implications for our understanding of biomineralization, but also of the means by which crystallization may be controlled in medical, pharmaceutical, and industrial contexts.

  3. Production of Calcite (Calcium Carbonate) Crystals by Soil Bacteria is a General Phenomenon

    Microsoft Academic Search

    E. Boquet; A. Boronat; A. Ramos-Cormenzana

    1973-01-01

    CERTAIN bacteria form crystals from the solutes in their aqueous environment, and some authors have associated this activity with the extensive deposits of CaCO3 in such places as the Grand Bahama, in spite of the belief that physicochemical effects, such as rapid changes in pH, salinity and temperature, are responsible1-4. Drew5 isolated a denitrifying bacterium able to form CaCO3 crystals

  4. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...calcium hydroxide in the “Carbonation process”; or (3) By precipitation of calcium carbonate from calcium chloride in the “Calcium chloride process”. (b) The ingredient meets the specifications of the Food Chemicals...

  5. DISSOLUTION AND CRYSTALLIZATION OF CALCIUM SULFITE PLATELETS

    EPA Science Inventory

    The paper discusses the dissolution and crystallization of calcium sulfite platelets. The rates of calcium sulfite dissolution and crystallization are important in slurry scrubbing processes for flue gas desulfurization. The rates affect the scrubber solution composition, SO2 abs...

  6. Control of calcium carbonate crystallization by using anionic polymethylsiloxanes as templates

    SciTech Connect

    Neira-Carrillo, Andronico, E-mail: aneira@uchile.cl [Faculty of Veterinary and Animal Sciences, University of Chile, Santa Rosa 11735, PO Box 2-15, Santiago (Chile)] [Faculty of Veterinary and Animal Sciences, University of Chile, Santa Rosa 11735, PO Box 2-15, Santiago (Chile); Vasquez-Quitral, Patricio; Paz Diaz, Maria; Soledad Fernandez, Maria; Luis Arias, Jose [Faculty of Veterinary and Animal Sciences, University of Chile, Santa Rosa 11735, PO Box 2-15, Santiago (Chile)] [Faculty of Veterinary and Animal Sciences, University of Chile, Santa Rosa 11735, PO Box 2-15, Santiago (Chile); Yazdani-Pedram, Mehrdad [Faculty of Chemical and Pharmaceutical Science, University of Chile, S. Livingstone 1007, PO Box 233, Santiago (Chile)] [Faculty of Chemical and Pharmaceutical Science, University of Chile, S. Livingstone 1007, PO Box 233, Santiago (Chile)

    2012-10-15

    Sulfonated (SO{sub 3}H-PMS) and carboxylated (CO{sub 2}H-PMS) polymethylsiloxanes were synthesized and their effects as anionic template modifier on the CaCO{sub 3} crystal morphologies were evaluated. In vitro crystallization assays of CaCO{sub 3} were performed at room temperature by using gas diffusion method at different concentration, pH and time. SEM images of CaCO{sub 3} showed well-defined short calcite piles (ca. 5 {mu}m) and elongated calcite (ca. 20 {mu}m) when SO{sub 3}H-PMS was used. When CO{sub 2}H-PMS was used, the morphology of CaCO{sub 3} crystals was single-truncated at pH 7-9 and aggregated-modified calcite at pH 10-11. However, at pH 12 the least stable donut-shaped vaterite crystals were formed. EDS and XRD confirmed the presence of Si from anionic PMS templates on the CaCO{sub 3} surfaces and its polymorphism, respectively. Results showed that the selective morphologies of CaCO{sub 3} reflect the electrostatic interaction of anionic groups of functionalized PMS with Ca{sup 2+} adsorbed on CaCO{sub 3} crystals. Rounded and truncated-modified fluorescent CaCO{sub 3} was also produced by the inclusion of functionalized PMS into the lattice of CaCO{sub 3} matrix. We demonstrated that the anionic PMS offer a good modifier for polymer-controlled crystallization and a convenient approach for understanding the biomineralization field. - Graphical abstract: Optical photographs of rounded and truncated-modified fluorescent CaCO{sub 3} produced by the inclusion of sulfonated (SO{sub 3}H-PMS) polymethylsiloxanes into the lattice of CaCO{sub 3} matrix. Insert represents the simulation of modified and fluorescent CaCO{sub 3} crystals using Software JCrystal, (2008). Highlights: Black-Right-Pointing-Pointer We prepared two anionic polymethylsiloxanes (PMS) as templates. Black-Right-Pointing-Pointer Their modifier capacity on the CaCO{sub 3} crystal morphologies was demonstrated. Black-Right-Pointing-Pointer At pH 12, the least stable donut-shaped vaterite, was formed. Black-Right-Pointing-Pointer EDS confirmed the presence of Si from anionic PMS templates on the CaCO{sub 3} surfaces. Black-Right-Pointing-Pointer Fluorescent CaCO{sub 3} was produced by the inclusion of PMS into the CaCO{sub 3} matrix.

  7. Engineering calcium oxalate crystal formation in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many plants accumulate crystals of calcium oxalate. Just how these crystals form remains unknown. To gain insight into the mechanisms regulating calcium oxalate crystal formation, a crystal engineering approach was initiated utilizing the non-crystal accumulating plant, Arabidopsis. The success of t...

  8. 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.

  9. Calcium carbonate microparticle growth controlled by a conjugate drug-copolymer and crystallization time.

    PubMed

    Doroftei, Florica; Damaceanu, Mariana Dana; Simionescu, Bogdan C; Mihai, Marcela

    2014-04-01

    The influence of crystallization reaction time on CaCO3 microparticle growth from supersaturate aqueous solutions, in the presence of a conjugate drug-copolymer, has been investigated. The polymer conjugate, P(NVP-MA-Ox), is based on poly(N-vinylpyrrolidone-co-maleic anhydride) as the support and 2-amino-5-(4-methoxyphenyl)-1,3,4-oxadiazole as the drug. The microparticles are characterized by optical, scanning and transmission electron microscopy, dynamic light scattering, X-ray diffraction, flow particle image analysis and particle charge density. X-ray diffraction (XRD) investigations showed that calcite polymorph content increased with an increase in crystallization time, even if the electrostatic interactions between Ca(2+) and polyanionic sites of P(NVP-MA-Ox) structure conduct to an increased vaterite phase stability. The strong particle size increase after 6?h of ageing can be ascribed to partially vaterite recrystallization and adsorption of nano-scaled calcite crystallite nuclei at microparticles surfaces. The pH stability of the particles was shown by zeta potential changes and their adsorption capacity as a function of their composition, and characteristics were tested using methylene blue. The sorption capacity of composite materials was strongly influenced by the ratio between polymorphs in the composites, and increased with the increase of calcite content and ageing time. PMID:24675592

  10. Doped nanocrystalline calcium carbonate phosphates

    Microsoft Academic Search

    L. F. Koroleva

    2010-01-01

    The formation of nanocrystalline calcium carbonate phosphates doped with Fe2+, Mg2, Zn2+, K+, Si4+, and Mn2+ has been studied by X-ray diffraction, IR spectroscopy, differential thermal analysis, and energy dispersive X-ray fluorescence\\u000a analysis. The results indicate that the synthesis involves the formation of hydroxy carbonate complexes from the three calcium\\u000a carbonate polymorphs (calcite, vaterite, and aragonite) in a solution of

  11. Significance of the Mucopolysaccharides in Calcium Carbonate Stone

    Microsoft Academic Search

    T. Maki; T. Sato; T. Matsushiro; N. Suzuki; S. Takasawa; M. Toyoda; N. Nakamura; M. Okada; Y. Kikuchi; T. Watanabe; T. Nemoto; T. Sanjo

    1968-01-01

    The present report deals with the histochemical and biochemical studies on the nature of the mucopolysacchari des which were thought to be the high molecular-weight organic substances in the calcium carbonate stone. The acid mucopolysacchari des were found, histochemically by alucian blue staining, between crystals of calcium carbonate in net-work fashion diffusely scattered throughout the sectioned material. Similar distribution of

  12. Calcium is incorporated into the calcium carbonate matrix of otoliths

    E-print Network

    118 Calcium is incorporated into the calcium carbonate matrix of otoliths and into the calcium). In addition to calcium, trace elements, such as strontium, are also incorporated into the calcified components valence) allow strontium ions to act as replace- ments for calcium during the pro- cess of calcification

  13. INTRODUCTION Pedogenic (secondary) calcium carbonate is,

    E-print Network

    Ahmad, Sajjad

    INTRODUCTION Pedogenic (secondary) calcium carbonate is, by definition, a product of soil processes of calcium for pe- dogenic calcium carbonate (Gile et al., 1979). In regard to the source of the carbonate; Cerling et al., 1989; Quade et al., 1989). Because pedogenic calcium carbonate is read- ily soluble, its

  14. Production of precipitated calcium carbonate from calcium silicates and carbon dioxide

    Microsoft Academic Search

    Sebastian Teir; Sanni Eloneva; Ron Zevenhoven

    2005-01-01

    The possibilities for reducing carbon dioxide emissions from the pulp and paper industry by calcium carbonation are presented. The current precipitated calcium carbonate (PCC) production uses mined, crushed calcium carbonate as raw materials. If calcium silicates were used instead, carbon dioxide emissions from the calcination of carbonates would be eliminated. In Finland, there could, thus, be a potential for eliminating

  15. Phase transitions in biogenic amorphous calcium carbonate

    PubMed Central

    Gong, Yutao U. T.; Killian, Christopher E.; Olson, Ian C.; Appathurai, Narayana P.; Amasino, Audra L.; Martin, Michael C.; Holt, Liam J.; Wilt, Fred H.; Gilbert, P. U. P. A.

    2012-01-01

    Crystalline biominerals do not resemble faceted crystals. Current explanations for this property involve formation via amorphous phases. Using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), here we examine forming spicules in embryos of Strongylocentrotus purpuratus sea urchins, and observe a sequence of three mineral phases: hydrated amorphous calcium carbonate (ACC·H2O) ? dehydrated amorphous calcium carbonate (ACC) ? calcite. Unexpectedly, we find ACC·H2O-rich nanoparticles that persist after the surrounding mineral has dehydrated and crystallized. Protein matrix components occluded within the mineral must inhibit ACC·H2O dehydration. We devised an in vitro, also using XANES-PEEM, assay to identify spicule proteins that may play a role in stabilizing various mineral phases, and found that the most abundant occluded matrix protein in the sea urchin spicules, SM50, stabilizes ACC·H2O in vitro. PMID:22492931

  16. CALCIUM CHANNELS INVOLVED IN CALCIUM OXALATE CRYSTAL FORMATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pistia stratiotes L. produces calcium (Ca) oxalate crystals in specialized cells called crystal idioblasts. Druse crystal idioblasts are produced in the adaxial mesophyll and raphide idioblasts are produced in the abaxial aerenchyma of this aquatic plant. Leaves formed on plants grown on 0 Ca medi...

  17. Polymorphs calcium carbonate on temperature reaction

    SciTech Connect

    Chong, Kai-Yin; Chia, Chin-Hua; Zakaria, Sarani [School of Applied Physics, Faculty Science and Technology, University Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

    2014-09-03

    Calcium carbonate (CaCO{sub 3}) has three different crystal polymorphs, which are calcite, aragonite and vaterite. In this study, effect of reaction temperature on polymorphs and crystallite structure of CaCO{sub 3} was investigated. X-ray powder diffraction (XRD), fourier transform infrared (FTIR), and variable pressure scanning electron microscope (VPSEM) were used to characterize the obtained CaCO{sub 3} particles. The obtained results showed that CaCO{sub 3} with different crystal and particle structures can be formed by controlling the temperature during the synthesis process.

  18. Calcium Oxalate Crystals in Eucalypt Ectomycorrhizae: Morphochemical Characterization

    PubMed Central

    Pylro, Victor Satler; de Freitas, André Luiz Moreira; Otoni, Wagner Campos; da Silva, Ivo Ribeiro; Borges, Arnaldo Chaer; Costa, Maurício Dutra

    2013-01-01

    Ectomycorrhizal fungi are ubiquitous in forest ecosystems, benefitting plants principally by increasing the uptake of water and nutrients such as calcium from the soil. Previous work has demonstrated accumulation of crystallites in eucalypt ectomycorrhizas, but detailed morphological and chemical characterization of these crystals has not been performed. In this work, cross sections of acetic acid-treated and cleared ectomycorrhizal fragments were visualized by polarized light microscopy to evaluate the location of crystals within cortical root cells. Ectomycorrhizal sections were also observed by scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDS) microprobe analysis. The predominant forms of crystals were crystal sand (granules) and concretions. Calcium, carbon and oxygen were detected by EDS as constituent elements and similar elemental profiles were observed between both crystal morphologies. All analyzed crystalline structures were characterized as calcium oxalate crystals. This is the first report of the stoichiometry and morphology of crystals occurring in eucalypt ectomycorrhizas in tropical soils. The data corroborates the role of ectomycorrhizae in the uptake and accumulation of calcium in the form of calcium oxalate crystals in hybrid eucalypt plants. PMID:23844062

  19. 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)

  20. Influence of calcium sources on microbially induced calcium carbonate precipitation by Bacillus sp. CR2.

    PubMed

    Achal, Varenyam; Pan, Xiangliang

    2014-05-01

    Stimulation of microbially induced calcium carbonate precipitation (MICCP) is likely to be influenced by calcium sources. In order to study such influences, we performed MICCP using Bacillus sp. CR2 in nutrient broth containing urea, supplemented with different calcium sources (calcium chloride, calcium oxide, calcium acetate and calcium nitrate). The experiment lasted 7 days, during which bacterial growth, urease activity, calcite production and pH were measured. Our results showed that calcium chloride is the better calcium source for MICCP process, since it provides higher urease activity and more calcite production. The influences of calcium sources on MICCP were further studied using Fourier transform-infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. These analyses confirmed that the precipitate formed was CaCO3 and composed of predominantly calcite crystals with a little amount of aragonite and vaterite crystals. The maximum yield of calcite precipitation was achievable with calcium chloride followed by calcium nitrate as a calcium source. The results of present study may be applicable to media preparation during efficient MICCP process. PMID:24643454

  1. Phosphate-water interplay tunes amorphous calcium carbonate metastability: spontaneous phase separation and crystallization vs stabilization viewed by solid state NMR.

    PubMed

    Kababya, Shifi; Gal, Assaf; Kahil, Keren; Weiner, Steve; Addadi, Lia; Schmidt, Asher

    2015-01-21

    Organisms tune the metastability of amorphous calcium carbonates (ACC), often by incorporation of additives such as phosphate ions and water molecules, to serve diverse functions, such as modulating the availability of calcium reserves or constructing complex skeletal scaffolds. Although the effect of additive distribution on ACC was noted for several biogenic and synthetic systems, the molecular mechanisms by which additives govern ACC stability are not well understood. By precipitating ACC in the presence of different PO4(3-) concentrations and regulating the initial water content, we identify conditions yielding either kinetically locked or spontaneously transforming coprecipitates. Solid state NMR, supported by FTIR, XRD, and electron microscopy, define the interactions of phosphate and water within the initial amorphous matrix, showing that initially the coprecipitates are homogeneous molecular dispersions of structural water and phosphate in ACC, and a small fraction of P-rich phases. Monitoring the transformations of the homogeneous phase shows that PO4(3-) and waters are extracted first, and they phase separate, leading to solid-solid transformation of ACC to calcite; small part of ACC forms vaterite that subsequently converts to calcite. The simultaneous water-PO4(3-) extraction is the key for the subsequent water-mediated accumulation and crystallization of hydroxyapatite (HAp) and carbonated hydroxyapatite. The thermodynamic driving force for the transformations is calcite crystallization, yet it is gated by specific combinations of water-phosphate levels in the initial amorphous coprecipitates. The molecular details of the spontaneously transforming ACC and of the stabilized ACC modulated by phosphate and water at ambient conditions, provide insight into biogenic and biomimetic pathways. PMID:25523637

  2. Epidemiology of calcium pyrophosphate crystal arthritis and basic calcium phosphate crystal arthropathy.

    PubMed

    Abhishek, Abhishek; Doherty, Michael

    2014-05-01

    Calcium pyrophosphate crystal deposition (CPPD) is common and mainly associates with increasing age and osteoarthritis (OA). Recent studies suggest that CPPD occurs as the result of a generalized articular predisposition and may also associate with low cortical bone mineral density. The epidemiology of basic calcium phosphate (BCP) crystal deposition is poorly understood. Although periarticular BCP crystal deposits occurs at all ages and in both sexes, intra-articular BCP crystal deposition tends to associate with increasing age and OA. Calcium pyrophosphate and BCP crystals frequently coexist in joints with OA. PMID:24703342

  3. Polypropylene\\/calcium carbonate nanocomposites

    Microsoft Academic Search

    Chi-Ming Chan; Jingshen Wu; Jian-Xiong Li; Ying-Kit Cheung

    2002-01-01

    Polypropylene (PP) and calcium carbonate nanocomposites were prepared by melt mixing in a Haake mixer. The average primary particle size of the CaCO3 nanoparticles was measured to be about 44nm. The dispersion of the CaCO3 nanoparticles in PP was good for filler content below 9.2vol%. Differential scanning calorimetry (DSC) results indicated that the CaCO3 nanoparticles are a very effective nucleating

  4. Calcium phosphate scaffold from biogenic calcium carbonate by fast ambient condition reactions

    NASA Astrophysics Data System (ADS)

    Dutta, Abhishek; Fermani, Simona; Arjun Tekalur, Srinivasan; Vanderberg, Abigail; Falini, Giuseppe

    2011-12-01

    Calcium phosphate biogenic materials are biocompatible and promote bioactivity and osteoconductivity, which implies their natural affinity and tendency to bond directly to bones subsequently replacing the host bone after implantation owing to its biodegradability. Calcium hydrogen phosphate dihydrate, CaHPO 4·2H 2O, is known to be a nucleation precursor, in aqueous solutions, for apatitic calcium phosphates and, hence, a potential starting material for bone substitutes. Numerous approaches, via hydrothermal and ambient synthetic routes, have been used to produce calcium phosphate from biogenic calcium carbonate, taking advantage of the peculiar architecture and composition of the latter. In this article, the lamellar region of the cuttlefish bone ( Sepia officinalis) was used as a framework for the organized deposition of calcium phosphate crystals, at ambient conditions via a fast procedure involving an amorphous calcium carbonate intermediate, and ending with a conversion to calcium phosphate and a fixation procedure, thereby resulting in direct conversion of biogenic calcium carbonate into calcium phosphates at ambient conditions from the scale of months to hours.

  5. Physicochemical characterization of calcium strontium tartrate crystals

    Microsoft Academic Search

    K. Suryanarayana; S. M. Dharmaprakash

    1997-01-01

    Mixed single crystals of calcium strontium tartrate (CST) of high optical quality and morphological perfection have been grown from light irradiated sodium meta silicate gel medium at ambient temperature. The results obtained on characterization of CST crystals using EDX, chemical analysis, X-ray diffraction and infra-red spectral techniques are reported. A thermogravimetric study is carried out in order to study the

  6. Biosynthesis of l-Ascorbic Acid and Conversion of Carbons 1 and 2 of l-Ascorbic Acid to Oxalic Acid Occurs within Individual Calcium Oxalate Crystal Idioblasts1

    PubMed Central

    Kostman, Todd A.; Tarlyn, Nathan M.; Loewus, Frank A.; Franceschi, Vincent R.

    2001-01-01

    l-Ascorbic acid (AsA) and its metabolic precursors give rise to oxalic acid (OxA) found in calcium oxalate crystals in specialized crystal idioblast cells in plants; however, it is not known if AsA and OxA are synthesized within the crystal idioblast cell or transported in from surrounding mesophyll cells. Isolated developing crystal idioblasts from Pistia stratiotes were used to study the pathway of OxA biosynthesis and to determine if idioblasts contain the entire path and are essentially independent in OxA synthesis. Idioblasts were supplied with various 14C-labeled compounds and examined by micro-autoradiography for incorporation of 14C into calcium oxalate crystals. [14C]OxA gave heavy labeling of crystals, indicating the isolated idioblasts are functional in crystal formation. Incubation with [1-14C]AsA also gave heavy labeling of crystals, whereas [6-14C]AsA gave no labeling. Labeled precursors of AsA (l-[1-14C]galactose; d-[1-14C]mannose) also resulted in crystal labeling, as did the ascorbic acid analog, d-[1-14C]erythorbic acid. Intensity of labeling of isolated idioblasts followed the pattern OxA > AsA (erythorbic acid) > l-galactose > d-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via d-mannose and l-galactose is operational in individual P. stratiotes crystal idioblasts. These results are discussed with respect to fine control of calcium oxalate precipitation and the concept of crystal idioblasts as independent physiological compartments. PMID:11161021

  7. tice sites of calcium carbonate and affect Mars' soil geochemistry, and calcium carbonate can

    E-print Network

    Kounaves, Samuel P.

    tice sites of calcium carbonate and affect Mars' soil geochemistry, and calcium carbonate can sample. 18. Estimation of the concentration of calcium carbonate in the sample is uncertain because qualification model (17). Other carbonates have decomposition temperatures that are lower than that of calcite

  8. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.; Wentworth, S. J.

    1987-01-01

    Chips of glassy Lithology C of EETA79001 were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy to determine the mineralogy and petrogenesis of the glass that was shown by others to contain trapped Mars-like gases. Calcium carbonite was identified as massive to acicular crystals for which Ca, C, and O were the major elements. Calcium sulfate was identified as prismatic-acicular crystals with Ca and S as the major elements.

  9. Spinning up the polymorphs of calcium carbonate

    PubMed Central

    Boulos, Ramiz A.; Zhang, Fei; Tjandra, Edwin S.; Martin, Adam D.; Spagnoli, Dino; Raston, Colin L.

    2014-01-01

    Controlling the growth of the polymorphs of calcium carbonate is important in understanding the changing environmental conditions in the oceans. Aragonite is the main polymorph in the inner shells of marine organisms, and can be readily converted to calcite, which is the most stable polymorph of calcium carbonate. Both of these polymorphs are significantly more stable than vaterite, which is the other naturally occurring polymorph of calcium carbonate, and this is reflected in its limited distribution in nature. We have investigated the effect of high shear forces on the phase behaviour of calcium carbonate using a vortex fluidic device (VFD), with experimental parameters varied to explore calcium carbonate mineralisation. Variation of tilt angle, rotation speed and temperature allow for control over the size, shape and phase of the resulting calcium carbonate. PMID:24448077

  10. Structural Characteristics of Synthetic Amorphous Calcium Carbonate

    SciTech Connect

    Michel, F. Marc; MacDonald, Jason; Feng, Jian; Phillips, Brian L.; Ehm, Lars; Tarabrella, Cathy; Parise, John B.; Reeder, Richard J. (SBU)

    2008-08-06

    Amorphous calcium carbonate (ACC) is an important phase involved in calcification by a wide variety of invertebrate organisms and is of technological interest in the development of functional materials. Despite widespread scientific interest in this phase a full characterization of structure is lacking. This is mainly due to its metastability and difficulties in evaluating structure using conventional structure determination methods. Here we present new findings from the application of two techniques, pair distribution function analysis and nuclear magnetic resonance spectroscopy, which provide new insight to structural aspects of synthetic ACC. Several important results have emerged from this study of ACC formed in vitro using two common preparation methods: (1) ACC exhibits no structural coherence over distances > 15 {angstrom} and is truly amorphous; (2) most of the hydrogen in ACC is present as structural H{sub 2}O, about half of which undergoes restricted motion on the millisecond time scale near room temperature; (3) the short- and intermediate-range structure of ACC shows no distinct match to any known structure in the calcium carbonate system; and (4) most of the carbonate in ACC is monodentate making it distinctly different from monohydrocalcite. Although the structure of synthetic ACC is still not fully understood, the results presented provide an important baseline for future experiments evaluating biogenic ACC and samples containing certain additives that may play a role in stabilization of ACC, crystallization kinetics, and final polymorph selection.

  11. Effect of Langmuir monolayer of bovine serum albumin protein on the morphology of calcium carbonate

    E-print Network

    Xue, Zhong-Hui; Hu, Bin-Bin; Du, Zu-Liang; 10.1016/j.msec.2009.03.016

    2011-01-01

    Bovine serum albumin (BSA) Langmuir monolayer, as a model of biomineralization-associated proteins, was used to study its effect on regulated biomineralization of calcium carbonate. The effects of the BSA Langmuir monolayer and the concentration of the subphase solution on the nucleation and growth processes and morphology of the calcium carbonate crystal were investigated. The morphology and polymorphic phase of the resulting calcium carbonate crystals were characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Moreover, the interaction mechanisms of the subphase solution with the BSA Langmuir monolayer were discussed. It was found that BSA Langmuir monolayer could be used as a template to successfully manipulate the polymorphic phase and crystal morphology of calcium carbonate and had obvious influence on the oriented crystallization and growth. The final morphology or aggregation mode of the calcite crystal was closely dependent on the concentration of calcium bicarbonate...

  12. Calcium carbonate scale formation and control

    Microsoft Academic Search

    Jitka MacAdam; Simon A. Parsons

    2004-01-01

    This paper focuses on the complex problem of calcium carbonate scale formation on heated surfaces and the possibilities of controlling or reducing this problem. The development of scale is a multistage process and is affected by a number of factors, these include supersaturation, pH, temperature and flow velocity. Calcium carbonate deposition can be ameliorated by chemical, physical or biological methods

  13. Characterization of Medicago truncatula reduced calcium oxalate crystal mutant alleles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate crystal formation is common in plants. Formation of these crystals has been shown to function in plant defense, calcium regulation, and aluminum tolerance. Although calcium oxalate is common and plays important roles in plant development, our understanding of how these crystals form ...

  14. Crystallization of calcium sulfate on polymeric surfaces.

    PubMed

    Lin, Nancy H; Shih, Wen-Yi; Lyster, Eric; Cohen, Yoram

    2011-04-15

    Surface crystallization of calcium sulfate dihydrate (gypsum) on a series of polymeric surfaces was studied using a quartz microbalance system. Polyelectrolyte multilayer films (positively and negatively charged surfaces) were formed on the quartz crystal microbalance (QCM) sensors utilizing a layer-by-layer spin-assembly method. The kinetics of gypsum surface crystallization was quantified in terms of the evolution of gypsum mineral scale on the different surfaces. For comparison mineral scaling was also evaluated on silica and polyamide surfaces. For surfaces of the same charge polarity (+/-), the mass density of gypsum scale was lower (PSScrystal growth kinetics. Although aerial scale coverage correlated with the crystal mass density, the crystal number density did not correlate with the extent of surface scaling. Surface crystal size, morphology and crystal number density varied significantly at similar roughness levels, suggesting that surface chemical functionality may also affect surface crystallization. The present results suggest that there is merit in exploring methods for mitigation of mineral scaling on polymeric surfaces via alteration of surface both surface topography and chemistry. In this regards, an expanded systematic study is needed in order to quantitatively clarify the interplay between the above two factors in controlling surface crystallization. PMID:21316694

  15. CALCIUM SULFITE CRYSTAL SIZING STUDIES

    EPA Science Inventory

    The report describes a reliable experimental method that can be used routinely to determine the crystal size distribution function, a measure that is required for a mathematical representation of the nucleation and growth processes involved in the settling, dewatering, and dispos...

  16. On the growth of calcium tartrate tetrahydrate single crystals

    Microsoft Academic Search

    X. Sahaya Shajan; C. Mahadevan

    2004-01-01

    Calcium tartrate single crystals were grown using silica gel as the growth medium. Calcium formate mixed with formic acid\\u000a was taken as the supernatant solution. It was observed that the nucleation density was reduced and the size of the crystals\\u000a was improved to a large extent compared to the conventional way of growing calcium tartrate crystals with calcium chloride.\\u000a The

  17. Molecular mechanisms of crystallization impacting calcium phosphate cements

    PubMed Central

    Giocondi, Jennifer L.; El-Dasher, Bassem S.; Nancollas, George H.; Orme, Christine A.

    2010-01-01

    The biomineral calcium hydrogen phosphate dihydrate (CaHPO4·2H2O), known as brushite, is a malleable material that both grows and dissolves faster than most other calcium minerals, including other calcium phosphate phases, calcium carbonates and calcium oxalates. Within the body, this ready formation and dissolution can play a role in certain diseases, such as kidney stone and plaque formation. However, these same properties, along with brushite’s excellent biocompatibility, can be used to great benefit in making resorbable biomedical cements. To optimize cements, additives are commonly used to control crystallization kinetics and phase transformation. This paper describes the use of in situ scanning probe microscopy to investigate the role of several solution parameters and additives in brushite atomic step motion. Surprisingly, this work demonstrates that the activation barrier for phosphate (rather than calcium) incorporation limits growth kinetics and that additives such as magnesium, citrate and bisphosphonates each influence step motion in distinctly different ways. Our findings provide details of how, and where, molecules inhibit or accelerate kinetics. These insights have the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. PMID:20308110

  18. Incorporation of Chromate into Calcium Carbonate Structure during Coprecipitation

    SciTech Connect

    Hua, Bin; Deng, Baolin; Thornton, Edward C.; Yang, J.; Amonette, James E.

    2006-09-08

    To assess treatment technologies and establish regulatory framework for chromate-contaminated site remediation, it is imperative to know the exact chromium speciation in soil matrices. In an earlier study, Thornton and Amonette (1999) reported that some chromate in the bulk particles was not accessible to gaseous reductants or solution-phase extractants, based on XANES studies. We hypothesized that part of this non-extractable chromate may reside in the structure of minerals such as calcium carbonate. To test this hypothesis, a number of calcium carbonate precipitates were prepared in the presence of various concentrations of chromate during the precipitation, which could coprecipitate chromate, or by adding chromate after the precipitation was completed. Hydrochloric acid was used to dissolve calcium carbonate and therefore extract the coprecipitated and surface attached chromate. The results showed that the coprecipitated chromate was non-extractable by hot alkaline solution or phosphate buffer, but could be solubilized by HCl in proportional to the amount of calcium carbonate dissolved. The X-ray diffraction experiments revealed that the coprecipitation of chromate with calcium carbonate had an influence on its crystal structure: the higher the chromate concentration, the greater the ratio of vaterite to calcite.

  19. Growth of nanofibrous barium carbonate on calcium carbonate seeds

    NASA Astrophysics Data System (ADS)

    Homeijer, Sara J.; Olszta, Matthew J.; Barrett, Richard A.; Gower, Laurie B.

    2008-05-01

    Fibrous barium carbonate (BaCO 3/witherite) crystals 50-100 nm in diameter and several microns in length were grown on calcium carbonate (CaCO 3) seeds at temperatures as low as 4 °C. The BaCO 3 fibers were deposited onto calcite rhombs or CaCO 3 films using the polymer-induced liquid-precursor (PILP) process, which was induced with the sodium salt of polyacrylic acid (PAA). The structure and morphology of the resultant fibers were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and polarized light microscopy (PLM). Fibers were successfully grown on calcite seeds of various morphologies, with a range of barium concentrations, and PAA molecular weight and concentration. Two categories of fibers were grown: straight and twisted. Both types of fibers displayed single-crystalline SAED diffraction patterns, but after examining high-resolution TEM lattice images, it was revealed that the fibers were in fact made up of nanocrystalline domains. We postulate that these nanocrystalline domains are well aligned due to a singular nucleation event (i.e., each fiber propagates from a single nucleation event on the seed crystal) with the nanocrystalline domains resulting from stresses caused by dehydration during crystallization of the highly hydrated precursor phase. These BaCO 3 fibers grown on calcite substrates further illustrate the robustness and non-specificity of the PILP process.

  20. Reaction between Monocalcium Phosphate and Calcium Carbonate

    Microsoft Academic Search

    S. Larsen; D. J. Parton; Inga-Lisa Svensson

    1963-01-01

    WHEN an acid phosphate is applied to a soil containing calcium carbonate or mixed with liming material a reaction will occur leading to the formation of more basic phosphates such as dicalcium phosphate, octocalcium phosphate and hydroxyapatite.

  1. [Features of calcium crystals and calcium components in 54 plant species in salinized habitats of Tianjin].

    PubMed

    Xu, Jing-Jing; Ci, Hua-Cong; He, Xing-Dong; Xue, Ping-Ping; Zhao, Xue-Lai; Guo, Jian-Tan; Gao, Yu-Bao

    2012-05-01

    Plant calcium (Ca) is composed of dissociated Ca2+ and easily soluble, slightly soluble, and hard soluble combined Ca salts. The hard soluble Ca salts can often engender Ca crystals. To understand the Ca status in different growth form plants in salinized habitats, 54 plant species were sampled from the salinized habitats in Tianjin, with the Ca crystals examined by microscope and the Ca components determined by sequential fractionation procedure. More Ca crystals were found in 38 of the 54 plant species. In 37 of the 38 plant species, drusy and prismatic Ca oxalate crystals dominated, whereas the cystolith of Ca carbonate crystal only appeared in the leaves of Ficus carica of Moraceae. The statistics according to growth form suggested that deciduous arbors and shrubs had more Ca oxalate crystal, liana had lesser Ca oxalate crystal, and herbs and evergreen arbors had no Ca oxalate crystal. From arbor, shrub, liana to herb, the concentration of HCl-soluble Ca decreased gradually, while that of water soluble Ca was in adverse. The concentration of water soluble Ca in herbs was significantly higher than that in arbors and shrubs. This study showed that in salinized habitats, plant Ca crystals and Ca components differed with plant growth form, and the Ca oxalate in deciduous arbors and shrubs played an important role in withstanding salt stress. PMID:22919834

  2. 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.

  3. 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 (?) 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.

  4. 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. PMID:25842135

  5. Influence of calcium oxalate crystal accumulation on the calcium content of seeds from Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crystals of calcium oxalate often form in cells adjacent to the vascular bundles in the tissues along the xylem stream. This spatial crystal pattern suggests a role for calcium oxalate formation in regulating calcium transport and partitioning to edible organs such as seeds. To investigate this pote...

  6. Effect of Langmuir monolayer of bovine serum albumin protein on the morphology of calcium carbonate

    E-print Network

    Zhong-Hui Xue; Shu-Xi Dai; Bin-Bin Hu; Zu-Liang Du

    2011-06-14

    Bovine serum albumin (BSA) Langmuir monolayer, as a model of biomineralization-associated proteins, was used to study its effect on regulated biomineralization of calcium carbonate. The effects of the BSA Langmuir monolayer and the concentration of the subphase solution on the nucleation and growth processes and morphology of the calcium carbonate crystal were investigated. The morphology and polymorphic phase of the resulting calcium carbonate crystals were characterized by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Moreover, the interaction mechanisms of the subphase solution with the BSA Langmuir monolayer were discussed. It was found that BSA Langmuir monolayer could be used as a template to successfully manipulate the polymorphic phase and crystal morphology of calcium carbonate and had obvious influence on the oriented crystallization and growth. The final morphology or aggregation mode of the calcite crystal was closely dependent on the concentration of calcium bicarbonate solution. It is expected that this research would help to better understand the mechanism of biomineralization by revealing the interactions between protein matrices and crystallization of calcium carbonate crystal.

  7. Calcium crystal-associated arthropathy (pseudogout) in a dog.

    PubMed

    de Haan, J J; Andreasen, C B

    1992-04-01

    Calcium pyrophosphate dihydrate (Ca2P2O7.2H2O) crystal-associated arthropathy (pseudogout) was diagnosed in a dog. Clinical signs included non-weightbearing lameness, signs of pain on joint manipulation, and high rectal temperature. Arthrocentesis of carpal joints revealed extra- and intracellular crystals containing calcium. The suspected cause was polyarthritis secondary to chronic Ehrlichia infection. Results of joint tap performed after resolution of the clinical signs were negative for calcium pyrophosphate dihydrate crystals. PMID:1577646

  8. Effects of DPPC/Cholesterol liposomes on the properties of freshly precipitated calcium carbonate.

    PubMed

    Szcze?, A

    2013-01-01

    DPPC/Cholesterol liposomes of average diameter below 100nm were used as a matrix for calcium carbonate precipitation. Adsorption of calcium ions on the vesicles was determined via zeta potential measurement. It was found that with increasing calcium ions concentration the electrokinetic potential of the vesicles varied toward more positive values. The changes became smaller with the cholesterol content increase. Accumulation of calcium ions close to the vesicles membranes lead to attraction of CO(3)(2-) ions and enhances nucleation and growth of small calcium carbonate crystals that aggregates within lipid vesicles forming porous balls aggregates. However, dipalmitoylphosphatidylcholine (DPPC) does not change the CaCO(3) crystal forms and calcite is the only form obtained during precipitation. Moreover, the influence of the phospholipid on the calcium carbonate precipitation is enhanced by the induction of cholesterol to the lipid membranes. PMID:22796770

  9. Calcium Carbonate Budgets the Basic Framework -*

    E-print Network

    Kleypas, Joanie

    Calcium Carbonate Budgets ­ the Basic Framework -* *title provided by Jim Hendee #12 cementation - ? Enmar et al. 2000 Skeletal dissolution - ? ? * G is per surface area of the organism #12 aragonite #12;#12;Carbonate Chemistry CO2aq (CO2 + H2O) H2CO3 CO2 HCO3 ­ + H+ CO3 2­ + H+ bicarbonate

  10. Molecular modulation of calcium oxalate crystallization.

    PubMed

    De Yoreo, James J; Qiu, S Roger; Hoyer, John R

    2006-12-01

    Calcium oxalate monohydrate (COM) is the primary constituent of the majority of renal stones. Osteopontin (OPN), an aspartic acid-rich urinary protein, and citrate, a much smaller molecule, are potent inhibitors of COM crystallization at levels present in normal urine. Current concepts of the role of site-specific interactions in crystallization derived from studies of biomineralization are reviewed to provide a context for understanding modulation of COM growth at a molecular level. Results from in situ atomic force microscopy (AFM) analyses of the effects of citrate and OPN on growth verified the critical role of site-specific interactions between these growth modulators and individual steps on COM crystal surfaces. Molecular modeling investigations of interactions of citrate with steps and faces on COM crystal surfaces provided links between the stereochemistry of interaction and the binding energy levels that underlie mechanisms of growth modification and changes in overall crystal morphology. The combination of in situ AFM and molecular modeling provides new knowledge that will aid rationale design of therapeutic agents for inhibition of stone formation. PMID:17082348

  11. Evaluation of quick disintegrating calcium carbonate tablets

    Microsoft Academic Search

    Hector Fausett; Charles Gayser Jr; Alekha K. Dash

    2000-01-01

    The purpose of this investigation was to develop a rapidly disintegrating calcium carbonate (CC) tablet by direct compression\\u000a and compare it with commercially available calcium tablets. CC tablets were formulated on a Carver press using 3 different\\u000a forms of CC direct compressed granules (Cal-Carb 4450®, Cal-Carb 4457®, and Cal-Carb 4462®). The breaking strength was measured using a Stokes-Monsanto hardness tester.

  12. Rheological and NMR studies of polyethylene/calcium carbonate composites.

    PubMed

    Nowaczyk, G; G?owinkowski, S; Jurga, S

    2004-01-01

    Rheometry, 13C CP/MAS NMR spectra and 1H spin-lattice relaxation times T1 and T1rho have been employed to study the structure and molecular dynamics in composites of polyethylene (LDPE) with calcium carbonate filler. It has been found that the addition of the filler into the polymer leads to an increase in composite rigidity and a decrease in mobility in its crystalline regions. The presence of the filler affects the crystallization process making the crystal structure less perfect and reduces the size of the crystallites. PMID:14698410

  13. Calcination of calcium carbonate and blend therefor

    DOEpatents

    Mallow, William A. (Helotes, TX); Dziuk, Jr., Jerome J. (San Antonio, TX)

    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.

  14. Calcium carbonate phase transformations during the carbonation reaction of calcium heavy alkylbenzene sulfonate overbased nanodetergents preparation.

    PubMed

    Chen, Zhaocong; Xiao, Shan; Chen, Feng; Chen, Dongzhong; Fang, Jianglin; Zhao, Min

    2011-07-01

    The preparation and application of overbased nanodetergents with excess alkaline calcium carbonate is a good example of nanotechnology in practice. The phase transformation of calcium carbonate is of extensive concern since CaCO(3) serves both as an important industrial filling material and as the most abundant biomineral in nature. Industrially valuable overbased nanodetergents have been prepared based on calcium salts of heavy alkylbenzene sulfonate by a one-step process under ambient pressure, the carbonation reaction has been monitored by the instantaneous temperature changes and total base number (TBN). A number of analytical techniques such as TGA, DLS, SLS, TEM, FTIR, and XRD have been utilized to explore the carbonation reaction process and phase transformation mechanism of calcium carbonate. An enhanced understanding on the phase transformation of calcium carbonate involved in calcium sulfonate nanodetergents has been achieved and it has been unambiguously demonstrated that amorphous calcium carbonate (ACC) transforms into the vaterite polymorph rather than calcite, which would be of crucial importance for the preparation and quality control of lubricant additives and greases. Our results also show that a certain amount of residual Ca(OH)(2) prevents the phase transformation from ACC to crystalline polymorphs. Moreover, a vaterite nanodetergent has been prepared for the first time with low viscosity, high base number, and uniform particle size, nevertheless a notable improvement on its thermal stability is required for potential applications. PMID:21507412

  15. CALCIUM OXALATE CRYSTAL MORPHOLOGY MUTANTS FROM MEDICAGO TRUNCATULA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants accumulate crystals of calcium oxalate in a variety of shapes and sizes. Each plant forms a crystal or set of crystals with a specific morphology. The mechanism(s) through which a plant defines the morphology of its crystals remains unknown. To gain insight into the mechanisms regulating c...

  16. Diagnosis and clinical manifestations of calcium pyrophosphate and basic calcium phosphate crystal deposition diseases.

    PubMed

    Ea, Hang-Korng; Lioté, Frédéric

    2014-05-01

    Basic calcium phosphate and pyrophosphate calcium crystals are the 2 main calcium-containing crystals that can deposit in all skeletal tissues. These calcium crystals give rise to numerous manifestations, including acute inflammatory attacks that can mimic alarming and threatening differential diagnoses, osteoarthritis-like lesions, destructive arthropathies, and calcific tendinitis. Awareness of uncommon localizations and manifestations such as intraspinal deposition (eg, crowned dens syndrome, tendinitis of longus colli muscle, massive cervical myelopathy compression) prevents inappropriate procedures and cares. Coupling plain radiography, ultrasonography, computed tomography, and synovial fluid analysis allow accurate diagnosis by directly or indirectly identifying the GRAAL of microcrystal-related symptoms. PMID:24703344

  17. Supercritical carbonation of calcium aluminate cement

    Microsoft Academic Search

    L. Fernández-Carrasco; J. Rius; Carles Miravitlles

    2008-01-01

    The microstructural changes occurring during supercritical carbonation (scCO2) of calcium aluminate cement (CAC) and changes to its strength have been investigated. Cylindrical specimens of CAC cured at different temperatures were prepared and then subjected to scCO2. It is shown that CAC carbonation in supercritical conditions is accelerated with a positive effect on the compressive strength. Due to the scCO2 treatment,

  18. CALCIUM CARBONATE BUDGET OF THE SOUTHERN CALIFORNIA CONTINENTAL BORDERLAND

    E-print Network

    Luther, Douglas S.

    CALCIUM CARBONATE BUDGET OF THE SOUTHERN CALIFORNIA CONTINENTAL BORDERLAND A DISSERTATION SUBMITTED. I. Murphy K. J. Roy E.· D..·· Stroup A. H. Woodcock #12;iv ABSTRACT Calcium carbonate sedimentation is the change in amount of calcium carbonate in the Borderland with time. Transfer can be divided

  19. Flocculation kinetics of precipitated calcium carbonate

    Microsoft Academic Search

    Roger Gaudreault; Nicolas Di Cesare; David Weitz

    2009-01-01

    When the percentage of filler in paper is increased, the optical properties are improved and the production cost lowered. However, fillers weaken paper strength by decreasing the fibre–fibre bonded area. Little is known about the optimum filler floc size or filler floc properties to allow developing optimum paper characteristics. Consequently, the kinetics of aggregation of scalenohedral precipitated calcium carbonate (PCC)

  20. Hydroxyapatite-calcium carbonate ceramic composite materials

    Microsoft Academic Search

    M. A. Gol’dberg; V. V. Smirnov; S. V. Kutsev; T. V. Shibaeva; L. I. Shvorneva; N. S. Sergeeva; I. K. Sviridova; S. M. Barinov

    2010-01-01

    Hydroxyapatite\\/calcium carbonate (CC) composite powders containing up to 50 wt % CO32?, have been prepared via precipitation from aqueous solutions. According to chemical analysis data, the CO32? content of the powders coincides with the intended one over the entire composition range studied. With increasing CO32? content, the specific surface area of the powders decreases because of the formation and growth

  1. 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

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

    PubMed

    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

  3. Epitaxial Relationships between Calcium Carbonate and Inorganic Substrates

    PubMed Central

    Yang, Taewook; Jho, Jae Young; Kim, Il Won

    2014-01-01

    The polymorph-selective crystallization of calcium carbonate has been studied in terms of epitaxial relationship between the inorganic substrates and the aragonite/calcite polymorphs with implication in bioinspired mineralization. EpiCalc software was employed to assess the previously published experimental results on two different groups of inorganic substrates: aragonitic carbonate crystals (SrCO3, PbCO3, and BaCO3) and a hexagonal crystal family (?-Al2O3, ?-SiO2, and LiNbO3). The maximum size of the overlayer (aragonite or calcite) was calculated for each substrate based on a threshold value of the dimensionless potential to estimate the relative nucleation preference of the polymorphs of calcium carbonate. The results were in good agreement with previous experimental observations, although stereochemical effects between the overlayer and substrate should be separately considered when existed. In assessing the polymorph-selective nucleation, the current method appeared to provide a better tool than the oversimplified mismatch parameters without invoking time-consuming molecular simulation\\. PMID:25226539

  4. Effects of PAA additive and temperature on morphology of calcium carbonate particles

    Microsoft Academic Search

    Jiaguo Yu; Ming Lei; Bei Cheng; Xiujian Zhao

    2004-01-01

    Calcium carbonate particles with various shapes were prepared by the reaction of sodium carbonate with calcium chloride in the absence and presence of a polyacrylic acid (PAA) at 25°C and 80°C, respectively. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The effects of pH, temperatures, aging time and concentration of PAA and CaCO3 on the crystal

  5. Hypercalcemic crisis induced by calcium carbonate

    PubMed Central

    Singh, Ashutosh; Ashraf, Ambika

    2012-01-01

    We report a rare case of drug-induced hypercalcemic crisis in an elderly male resulting from calcium-containing supplements facilitated by thiazide diuretic and angiotensin-converting enzyme inhibitor. A 61-year-old male presented with hypercalcemic crisis along with renal insufficiency and metabolic alkalosis, mimicking the ‘calcium-alkali syndrome’. The patient responded to aggressive intravenous hydration along with emergent hemodialysis and salmon calcitonin. He did not have hyperparathyroidism or malignancy. History revealed an average daily intake of only 1200 mg of calcium carbonate along with vitamin D 1000 U/day over an extended period of time. The patient completely recovered in 3 days and had normal serum calcium, parathyroid hormone and phosphorous level at 3-month follow-up. The case highlights the life-threatening perils of indiscriminate and often excessive intake of calcium-containing supplements in an appropriate clinical setting. We also briefly discuss the epidemiology, clinical and laboratory features along with the recent advances in the understanding of the pathophysiology of calcium-alkali syndrome.

  6. Sr Incorporation and Calcium Isotopic Fractionation during Calcium Carbonate Precipitation

    NASA Astrophysics Data System (ADS)

    Niedermayr, A.; Dietzel, M.; Köhler, S. J.; Böhm, F.; Kisakurek, B.; Eisenhauer, A.

    2009-04-01

    Element substitution and calcium isotopic fractionation can provide information about the mechanisms of CaCO3 precipitation, precipitation rates, temperatures and solution chemistry. In the present study precipitation experiments for the formation of the CaCO3 polymorphs: calcite, aragonite and vaterite were carried out. Calcium carbonates are formed at various Mg/Ca ratios or in presence of polyaspartic acid at temperatures between 5 and 40Ë? C at pH 8.3 by using an advanced CO2-diffusion technique (Tang et al., 2008). The results indicate elevated Sr distribution coefficients (DSr) during calcite and vaterite formation at increasing precipitation rates, whereas DSr-values decrease only slightly with increasing rate during the formation of aragonite. 44Ca/40Ca fractionation increases for aragonite and calcite formation as precipitation rates increase. Preliminary results show less calcium isotopic fractionation for vaterite compared to calcite and aragonite. However, 44?40CaCaCO3(s)-Ca(aq)-values for the three modifications indicate an inverse correlation with DSr. Respective mechanisms and proposed models are discussed. Reference Tang J., Köhler S.J., and Dietzel M. (2008) Sr2+/Ca2+ and 44Ca/40Ca fractionation during inorganic calcite formation: I. Sr in corporation, Geochimica et Cosmochimica Acta, 72, 3718-3732.

  7. Preparation and Characterization of Calcium Carbonate Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hassim, Aqilah; Rachmawati, Heni

    2010-10-01

    Taking calcium supplements can reduce the risk of developing osteoporosis, but they are not readily absorbed in the gastrointestinal tract. Nanotechnology is expected to resolve this problem. In this study, we prepared and characterized calcium carbonate nanoparticle to improve the solubility by using bottom-up method. The experiment was done by titrating calcium chloride with sodium carbonate with the addition of polyvinylpyrrolidone (PVP) as stabilizer, using ultra-turrax. Various concentrations of calcium chloride and sodium carbonate as well as various speed of stirring were used to prepare the calcium carbonate nanoparticles. Evaluations studied were including particle size, polydispersity index (PI) and zeta potential with particle analyzer, surface morphology with scanning electron microscope, and saturated solubility. In addition, to test the ability of PVP to prevent particles growth, short stability study was performed by storing nano CaCO3 suspension at room temperature for 2 weeks. Results show that using 8000 rpm speed of stirring, the particle size tends to be bigger with the range of 500-600 nm (PI between 0.2-0.4) whereas with stirring speed of 4000 rpm, the particle size tends to be smaller with 300-400 nm (PI between 0.2-0.4). Stirring speed of 6000 rpm produced particle size within the range of 400-500 nm (PI between 0.2-0.4). SEM photograph shows that particles are monodisperse confirming that particles were physically stable without any agglomeration within 2 weeks storage. Taken together, nano CaCO3 is successfully prepared by bottom-up method and PVP is a good stabilizer to prevent the particle growth.

  8. INVESTIGATIONS INTO CALCIUM OXALATE CRYSTAL FORMATION IN MEDICAGO TRUNCATULA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate crystal formation is common in nature. Plants accumulate crystals in a variety of shapes, sizes, amounts, and spatial locations. To gain insight into the mechanisms regulating crystal formation, we have conducted a mutant screen of a chemically mutagenized Medicago truncatula popul...

  9. Surface modification of precipitated calcium carbonate using aqueous fluosilicic acid

    Microsoft Academic Search

    Do Su Kim; Churl Kyoung Lee

    2002-01-01

    Surface modification of calcium carbonate using aqueous fluosilicic acid (H2SiF6) was carried out in terms of the mole ratio of fluosilicic acid to calcium carbonate as well contact time. The resulting surface compounds of amorphous silica and calcium fluoride after surface modification were visualized on the surface of calcium carbonate. Amorphous silica was generated by the hydrolysis of silicon hexafluoride

  10. Relative bioavailability of calcium from calcium formate, calcium citrate, and calcium carbonate

    E-print Network

    Hanzlik, Robert P.; Fowler, S. C.; Fisher, D. H.

    2005-06-01

    Published Abstract: Calcium is an essential nutrient required in substantial amounts, but many diets are deficient in calcium making supplementation necessary or desirable. The objective of this study was to compare the oral bioavailability...

  11. Experimental design approach to calcium carbonate precipitation in a semicontinuous process

    Microsoft Academic Search

    Marko Ukrainczyk; Jasminka Kontrec; Vesna Babi?-Ivan?i?; Ljerka Bre?evi?; Damir Kralj

    2007-01-01

    The production of precipitated calcium carbonate, PCC, by a semicontinuous process of slaked lime carbonation was performed in a bench-scale chemical reactor, fully controlled by means of custom built electronics and software for the personal computer. Calcite crystals, with different characteristic morphologies (rhombohedral, truncated prismatic, scalenohedral, spheroidal or chain-like agglomerates) were produced by varying a range of process parameters, like

  12. The occurrence of calcium in plant tissue as crystals of calcium oxalate

    Microsoft Academic Search

    R. N. Gallaher

    1975-01-01

    Calcium oxalate crystals were described in plant cells as early as 1865. Numerous accounts are found in the literature indicating that crystals occur in some species more abundantly than others and none occur in some plant species. The crystals have been observed and analyzed by transmitted light microscopy, polarized light microscopy, electron microprobe and by mechanical and chemical means. Plants

  13. Direct Observation of Completely Processed Calcium Carbonate Dust Particles

    Microsoft Academic Search

    Alexander Laskin; Martin J. Iedema; Aviad Ichkovich; Ellen R. Graber; Ilya Taraniuk; Yinon Rudich

    2005-01-01

    This study presents, for the first time, field evidence of complete, irreversible processing of solid calcium carbonate (calcite)-containing particles and quantitative formation of liquid calcium nitrate particles apparently as a result of heterogeneous reaction of calcium carbonate-containing mineral dust particles with gaseous nitric acid. Formation of nitrates from individual calcite and sea salt particles was followed as a function of

  14. Exotic behavior and crystal structures of calcium under pressure

    E-print Network

    Oganov, Artem R.

    Exotic behavior and crystal structures of calcium under pressure Artem R. Oganova,b,1 , Yanming Mac that calcium undergoes sev- eral counterintuitive transitions under pressure: fcc bcc simple cubic Ca-IV Ca-V, and becomes a good superconductor in the simple cubic and higher-pressure phases. Here, using ab initio

  15. Calcium carbonate scaling in solar collectors

    Microsoft Academic Search

    I. Singh; C. F. Cheng; R. M. Wolosewicz

    1981-01-01

    Water samples collected from five U.S. Department of Energy-sponsored solar-energy systems and eight water samples of varying degrees of hardness were assessed for tendency to form calcium carbonate scale on solar collector surfaces. A two-step approach is recommended for estimating scaling potential based on water analysis: (1) calculate the Palin Index, and (2) if the index shows a potential for

  16. Structural, Spectral And Optical Characterization Of Calcium Barium Tartrate Crystals

    NASA Astrophysics Data System (ADS)

    Freeda, M. Mary; Priya, R. Krishna; Freeda, T. H.; Delphine, S. Mary

    2011-10-01

    Single crystals of Calcium Barium tartrate (CBT) were grown by controlled diffusion in silica gel at ambient temperature. The structural characterization of the grown crystals was carried out by Powder X-ray diffraction analysis. The functional groups present in the crystals were identified using Fourier Transform Infrared spectral analysis. The UV-Vis-NIR transmission spectrum was recorded to study the optical transparency of the grown crystals.

  17. Carbon Nanotube Nucleated Polymer Crystallization

    Microsoft Academic Search

    K. P. Ryan; M. Cadek; A. Drury; M. Ruether; W. J. Blau; J. N. Coleman

    2005-01-01

    Crystallinity studies were performed on carbon nanotube?doped Poly(m?phenylenevinylene?co?2,5?dioctyloxy?p?phenylenevinylene) (PmPV) and Poly (vinyl alcohol) (PVOH). Differential Scanning Calorimetry (DSC) of the composites verified that carbon nanotubes nucleate polymer crystallization.

  18. CHARACTERIZATION OF ARTICULAR CALCIUM-CONTAINING CRYSTALS BY SYNCHROTRON FTIR

    PubMed Central

    Rosenthal, Ann K.; Mattson, Eric; Gohr, Claudia M.; Hirschmugl, Carol J.

    2008-01-01

    Objective Sixty percent of synovial fluids from patients with severe osteoarthritis contain calcium pyrophosphate dihydrate (CPPD) or basic calcium phosphate (BCP) crystals. These bioactive crystals can be particularly difficult to accurately identify in complex biologic systems, such as in vitro models of crystal formation. We sought to determine if synchrotron FTIR (sFTIR) could be used to identify and characterize calcium-containing crystals in mineralization models. Methods CPPD and BCP crystals from porcine models of crystal formation were examined with an FTIR Microscope attached to a synchrotron light source. As a comparison, crystals from human synovial fluids were also examined. The sFTIR spectra generated were compared with known spectra of multiple forms of BCP and CPPD crystals, as well as spectra generated by synthetic CPPD and BCP crystals and cartilage proteoglycans, alone and in mixtures. Results sFTIR readily identified CPPD and BCP crystals in porcine models as well as in fresh synovial fluids. Brushite was also present in human and porcine samples, and whitlockite was seen in some porcine samples. Mixtures of minerals were commonly found in a single crystal aggregate in both human and porcine samples. In spectra from many CPPD crystals, the peak at the 1134 cm?1 found on the standard spectrum for CPPD was diminished. Addition of spectra from cartilage proteoglycans to those of synthetic CPPD crystals dampened the peak at this frequency region, much as this peak was diminished in biologically-derived CPPD crystals. Conclusion sFTIR analysis allows for accurate identification of CPPD and BCP crystals generated in vitro and will a useful research tool to study articular crystals. PMID:18472285

  19. Influence of phosphate on cadmium sorption by calcium carbonate

    Microsoft Academic Search

    S. K. Thakur; N. K. Tomar; S. B. Pandeya

    2006-01-01

    Laboratory investigation was conducted to investigate the mechanism of cadmium sorption by pure calcium carbonate and to examine whether, reaction products of phosphate with calcium carbonate serve as a sink for sorption of toxic heavy metal cations like cadmium. The phosphatization of calcium carbonate (G.R) was carried out by treating it with orthophosphoric acid in Ca:P ratio of 5:3, 3:2,

  20. Bridgman growth of large-aperture yttrium calcium oxyborate crystal

    SciTech Connect

    Wu, Anhua, E-mail: wuanhua@mail.sic.ac.cn [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Jiang, Linwen; Qian, Guoxing; Zheng, Yanqing; Xu, Jun; Shi, Erwei [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2012-09-15

    Highlights: ? YCOB is a novel non-linear optical crystal possessing good thermal, mechanical and nonlinear optical properties. ? Large size crystal growth is key technology question for YCOB crystal. ? YCOB crystals 3 in. in diameter were grown with modified vertical Bridgman method. ? It is a more effective growth method to obtain large size and high quality YCOB crystal. -- Abstract: Large-aperture yttrium calcium oxyborate YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB) crystals with 3 in. in diameter were grown with modified vertical Bridgman method, and the large crystal plate (63 mm × 68 mm × 20 mm) was harvested for high-average power frequency conversion system. The crack, facet growth and spiral growth can be effectively controlled in the as-grown crystal, and Bridgman method displays more effective in obtain large size and high quality YCOB crystal plate than Czochralski technique.

  1. Br J Nutr . Author manuscript Calcium carbonate suppresses haem toxicity markers without calcium

    E-print Network

    Paris-Sud XI, Université de

    Br J Nutr . Author manuscript Page /1 9 Calcium carbonate suppresses haem toxicity markers without calcium phosphate side effects on colon carcinogenesis Ossama Allam , Diane Bahuaud , Sylviane Taché-induced preneoplastic lesions, aberrant crypt foci, in the colon of rats. We have also shown that dietary calcium

  2. A new antacid drug from activated carbon modified with calcium carbonate

    Microsoft Academic Search

    Carlos F. Linares; José Quintero; Lesbia Martínez; Gema González

    2007-01-01

    Activated carbons were previously modified with different sodium carbonate solutions and then, they were soaked in a calcium nitrate solution. This procedure allowed to precipitate calcium carbonate on the microporous carbons. Then, these solids were washed with abundant distillated water. These modified carbons were characterized by means of XRD, SEM, HRTEM and BET surface area measurements. XRD confirmed the presence

  3. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...true Applicability; description of the calcium carbonate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory....

  4. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...false Applicability; description of the calcium carbonate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory....

  5. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...true Applicability; description of the calcium carbonate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory....

  6. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...true Applicability; description of the calcium carbonate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory....

  7. QUANTIFYING GROWTH AND CALCIUM CARBONATE DEPOSITION OF CALLIARTHRON CHEILOSPORIOIDES (CORALLINALES, RHODOPHYTA)

    E-print Network

    Martone, Patrick T.

    NOTE QUANTIFYING GROWTH AND CALCIUM CARBONATE DEPOSITION OF CALLIARTHRON CHEILOSPORIOIDES Station of Stanford University, Pacific Grove, California 93950, USA Growth and calcium carbonate measurement of growth and calcium carbonate deposition at each meristem. In Calliarthron, meristematic

  8. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...true Applicability; description of the calcium carbonate production subcategory. 415...CHEMICALS MANUFACTURING POINT SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory....

  9. In vitro synthesis and stabilization of amorphous calcium carbonate (ACC) nanoparticles within liposomes

    SciTech Connect

    Tester, Chantel C.; Brock, Ryan E.; Wu, Ching-Hsuan; Krejci, Minna R.; Weigand, Steven; Joester, Derk (NWU)

    2012-02-07

    We show that amorphous calcium carbonate (ACC) can be synthesized in phospholipid bilayer vesicles (liposomes). Liposome-encapsulated ACC nanoparticles are stable against aggregation, do not crystallize for at least 20 h, and are ideally suited to investigate the influence of lipid chemistry, particle size, and soluble additives on ACC in situ.

  10. Biochemical and ultrastructural evidence for the origin of whitings: A biologically induced calcium carbonate precipitation mechanism

    Microsoft Academic Search

    L. L. Robbins; P. L. Blackwelder

    1992-01-01

    We propose that Bahamian whitings, floating patches of lime mud, are in part the result of biological precipitation of calcium carbonate induced by picoplankton and cellular components. The cells may act as nucleation sites for crystallization from seawater supersaturated with CaCO3. Our model represents a new hypothesis concerning Bahamian whiting formation and is based on several lines of evidence. Biochemical

  11. Amorphous Calcium Carbonate Transforms into Calcite during Sea Urchin Larval Spicule Growth

    Microsoft Academic Search

    Elia Beniash; Joanna Aizenberg; Lia Addadi; Stephen Weiner

    1997-01-01

    Sea urchin larvae form an endoskeleton composed of a pair of spicules. For more than a century it has been stated that each spicule comprises a single crystal of the CaCO3 mineral, calcite. We show that an additional mineral phase, amorphous calcium carbonate, is present in the sea urchin larval spicule, and that this inherently unstable mineral transforms into calcite

  12. Sea Urchin Spine Calcite Forms via a Transient Amorphous Calcium Carbonate Phase

    Microsoft Academic Search

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

    2004-01-01

    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

  13. Surface energetics of calcium carbonates using inverse gas chromatography

    Microsoft Academic Search

    D. Steven Keller; Philip Luner

    2000-01-01

    Various calcium carbonate samples were characterized by inverse gas chromatography (IGC) at infinite dilution. The interactions between the samples and hydrocarbon probes, C5–C10 were related to the retention volume in gas chromatographic experiments. The surface energetics of chalk, marble and precipitated calcium carbonate (PCC) were determined in terms of the apolar component of the surface free energy ?SLW and the

  14. Production and dissolution rates of earthworm-secreted calcium carbonate

    Microsoft Academic Search

    D. C. Lambkin; K. H. Gwilliam; C. Layton; M. G. Canti; T. G. Piearce; M. E. Hodson

    Earthworms secrete granules of calcium carbonate. These are potentially important in soil biogeochemical cycles and are routinely recorded in archaeological studies of Quaternary soils. Production rates of calcium carbonate granules by the earthworm Lumbricus terrestris L. were determined over 27days in a range of soils with differing chemical properties (pH, organic matter content, water holding capacity, bulk composition, cation exchange

  15. The formation and transformation mechanism of calcium carbonate in water

    Microsoft Academic Search

    Takeshi Ogino; Toshio Suzuki; Kiyoshi Sawada

    1987-01-01

    Highly supersaturated solutions of Ca 2+ and CO 2- 3 ions rapidly precipitate amorphous calcium carbonate, ACC, the logarithmic thermodynamic solubility product of which is about -6.0 at 25°C. The ACC initially formed is transformed to a mixture of several crystalline calcium carbonate polymorphs within several minutes. The transformed polymorphs are vaterite and calcite at low temperature (14 to 30°C),

  16. 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

  17. Calcium carbonate control in highly supersaturated aqueous environment

    SciTech Connect

    Gill, J.S.; Yorke, M.A. [Calgon Corp., Pittsburgh, PA (United States)

    1994-12-31

    Calcium carbonate is by far the most common scale in a variety of industrial processes, e.g., cooling waters, mining, oil production, municipal, household appliances and plumbing, and natural processes. Inhibition of calcium carbonate becomes increasingly difficult with increasing calcium carbonate supersaturation. Scarcity of good quality water and tougher water discharge regulations are driving higher reuse of water, which leads to higher cycles in recirculating cooling tower water. In terms of the supersaturation, which is a ratio of the product of free scale forming ions to the equilibrium solubility product, the water treatment industry in the past was able to control calcium carbonate inhibition up to 100--120X calcite supersaturation. This paper reports chemical technology capable of controlling calcium carbonate precipitation under highly alkaline conditions (pH above 9.0) >300X calcite supersaturation. Results of both laboratory and pilot studies are discussed in the paper.

  18. Calcium carbonate suppresses haem toxicity markers without calcium phosphate side effects on colon carcinogenesis

    PubMed Central

    Allam, Ossama; Bahuaud, Diane; Taché, Sylviane; Naud, Nathalie; Corpet, Denis E; Pierre, Fabrice H F

    2011-01-01

    Red meat intake is associated with increased risk of colorectal cancer. We have previously shown that haemin, haemoglobin and red meat promote carcinogen-induced preneoplastic lesions, aberrant crypt foci, in the colon of rats. We have also shown that dietary calcium phosphate inhibits haemin-induced promotion, and normalizes faecal lipoperoxides and cytotoxicity. Unexpectedly, high-calcium phosphate control diet-fed rats had more preneoplastic lesions in the colon than low-calcium control diet-fed rats. The present study was designed to find a calcium supplementation with no adverse effect, by testing several doses and types of calcium salts. One in vitro study and two short-term studies in rats identified calcium carbonate as the most effective calcium salt to bind haem in vitro and to decrease faecal biomarkers previously associated with increased carcinogenesis: faecal water cytotoxicity, thiobarbituric acid reactive substances. A long term carcinogenesis study in dimethylhydrazine-injected rats demonstrated that a diet containing 100 ?mol/g calcium carbonate did not promote aberrant crypt foci, in contrast with previously tested calcium phosphate diet. The results suggest that calcium carbonate, and not calcium phosphate, should be used to reduce haem-associated colorectal cancer risk in meat-eaters. They support the concept that the nature of the associated anion to a protective metal ion is important for chemoprevention. PMID:21134327

  19. Crystallization of calcium phosphate in microgravity

    NASA Astrophysics Data System (ADS)

    Madsen, H. E. Lundager; Christensson, F.; Chernov, A. A.; Polyak, L. E.; Suvorova, E. I.

    1995-08-01

    Dilute solutions of CaCl_2 and KH_2PO_4 + K_2HPO_4 were diffusing from either side into a mixing chamber with KCl solution. The microgravity experiment yielded aggregates of large crystals of OCP (Ca_8H_2(PO_4)_3,5H_2O) and spherolites of smaller, but still visible crystals of HAP (Ca_5OH(PO_4)_3), the stable final phase. Ground-based experiments yielded submicroscopic HAP crystals. Results of calculations of diffusion and crystal growth on the basis of previous knowledge agree well with observations.

  20. Single-Crystal Calcium Hexaboride Nanowires: Synthesis and

    E-print Network

    tantalum crucible,21 by carbothermal reduction of calcium carbonate (CaCO3) and boron carbide (B4C) at 1400 hexaboride (CaB6) nanowires was achieved by pyrolysis of diborane (B2H6) over calcium oxide (CaO) powders of TEM/EDX/EELS data proves the nanowires consist of CaB6 cores and thin (1-2 nm) amorphous oxide shell

  1. Morphology of crystals in calcium oxalate monohydrate kidney stones

    Microsoft Academic Search

    S. Sandersius; P. Rez

    2007-01-01

    Both scanning electron microscopy and atomic force microscopy (AFM) have shown that calcium oxalate monohydrate kidney stones\\u000a are made up from arrangements of sub micron crystals. The purpose of this investigation was to determine the morphology of\\u000a these crystals which was obscured by the presence of organic matrix in our earlier study. Sections of stones were treated\\u000a to remove the

  2. Physicochemical characteristics of Ba 2+ mixed calcium tartrate crystals

    Microsoft Academic Search

    K Suryanarayana; S. M Dharmaprakash

    2002-01-01

    Non-linear optical single crystals of barium mixed calcium tartrate tetrahydrate with molecular formula Ca0.8Ba0.2C4H4O6·4H2O (CBT) have been grown in gels using a chemical reaction method at ambient temperature. The physical and chemical characteristics of gel grown CBT crystals have been investigated by employing Vickers micro hardness, etching, and thermal techniques. The single crystalline habit of CBT is deviated from that

  3. Stability of calcium carbonate and magnesium carbonate in rainwater and nitric acid solutions

    Microsoft Academic Search

    Sebastian Teir; Sanni Eloneva; Carl-Johan Fogelholm; Ron Zevenhoven

    2006-01-01

    Carbonation of magnesium and calcium silicates has emerged as an interesting option for long term storage of captured CO2. However, carbonated minerals are not stable in acidic environments. This study was conducted to determine if synthetically carbonated minerals dissolve in acidic rain and release CO2. Synthetic magnesium and calcium carbonates were leached in nitric acid solutions of various acidities, as

  4. Behavior of carbon isotopes during the hyperfiltration of calcium carbonate solutions through calcium bentonites

    E-print Network

    Hinz, David William

    1987-01-01

    (aq) The 1sotopic ratio of the effluent gave no clue to the possible occurrence of any fractionation of carbon 1sotopes. The solution retained on the high pressure s1de of the membrane was found to have an increased calcium concentration, as would... the stock solution's COB(aq) concentration. This is interpreted as conversion of bicarbonate to CO7(aq) along or within the membrane, with subsequent transport of the C02~a ~ through the membrane. The carbon isotopic ratio of the throughput solution...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. Biogenic synthesis of calcium oxalate crystal by reaction of calcium ions with spinach lixivium.

    PubMed

    Li, Shi-Kuo; Xie, An-Jian; Shen, Yu-Hua; Yu, Xue-Rong; Hu, Gang

    2010-07-01

    In this paper, we report a biogenic synthesis protocol for preparation of calcium oxalate (CaC2O4, CaOx) crystal at room temperature by a simple protein-mediated reaction of aqueous Ca2+ ions with the C2O4(2-) ions spontaneously released from spinach. The aggregation of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) with a rod-like morphology was mainly formed in the spinach root lixivium, and the proportion of COM crystal in the aggregation increased with the concentration of Ca2+ ions increasing, however, spindle-shaped crystal was mainly obtained in the spinach leaf lixivium and the content of COM in the product was higher than that obtained in the root lixivium with the similar concentration of Ca2+ ions. COM phase disappeared and only COD crystal with morphology of tetragonal bipyramidal prisms presented in the product when the leaf lixivium was replaced by the leaf broth. The biomolecules such as proteins with molecular weight of 31kDa liberated from the spinach root are negative-charged, which played important roles for the control of CaOx crystal growth in the root lixivium corresponding to the changes of protein secondary structures after reaction with Ca2+ ions. This research was potentially important for unraveling the biomineralization mechanism of CaOx crystal. PMID:20399625

  7. Crystal growth of calcium sulphate dihydrate at low supersaturation

    NASA Astrophysics Data System (ADS)

    Christoffersen, M. R.; Christoffersen, J.; Weijnen, M. P. C.; Van Rosmalen, G. M.

    1982-08-01

    The growth rate of calcium sulphate dihydrate crystals, gypsum, in aqueous suspension has been shown to be screw dislocation controlled in the supersaturation range 1.03< {C}/{C s}<1.15 . Constant composition experiments show that the overall rate of growth decreases with increasing mass of the crystals. A combination of normal spiral growth, growth of cooperating spirals with non-parallel Burgers vectors, and growth of grain boundary spirals, together with partial outgrowth of concave parts of the crystals, can explain the rate of growth found for different preparations of gypsum crytals.

  8. Why to synthesize vaterite polymorph of calcium carbonate on the cellulose matrix via sonochemistry process?

    PubMed

    Fu, Lian-Hua; Dong, Yan-Yan; Ma, Ming-Guo; Yue, Wen; Sun, Shao-Long; Sun, Run-Cang

    2013-09-01

    Vaterite is an important biomedical material due to its features such as high specific surface area, high solubility, high dispersion, and small specific gravity. The purposes of this article were to explore the growth mechanism of vaterite on the cellulose matrix via sonochmistry process. In the work reported herein, the influences of experimental parameters on the polymorph of calcium carbonate were investigated in detail. The calcium carbonate crystals on the cellulose matrix were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results revealed that all the reactants, solvent, and synthesis method played an important role in the polymorph of calcium carbonate. The pure phase of vaterite polymorph was obtained using Na2CO3 as reactant in ethylene glycol on the cellulose matrix via sonochmistry process. Based on the experimental results, one can conclude that the synthesis of vaterite polymorph is a system process. PMID:23591018

  9. Crystal Morphology and 13Carbon/12Carbon Composition of Solid Oxalate in Cacti 1

    PubMed Central

    Rivera, E. R.; Smith, B. N.

    1979-01-01

    Morphology, crystal structure, and carbon isotopic composition of calcium oxalate from representative species from the family Cactaceae were determined using scanning electron microscopy, x-ray diffraction, and isotope ratio mass spectrometry. Crystals from one species in the Opuntieae tribe of the Cactaceae were druses with acute points composed of the monohydrate form of calcium oxalate (whewellite). Crystals from three species in the Cereeae tribe were the dihydrate form of calcium oxalate (weddellite) forming druses made up of tetragonal and isodiametric crystallites. The oxalate was relatively enriched in 13C isotope (-7.3 to - 8.7 ‰) compared with woody fibers (-13.3 to 14.1 ‰) from the same plants. Images PMID:16661115

  10. Effect of nanosized and surface-modified precipitated calcium carbonate on properties of CaCO 3\\/polypropylene nanocomposites

    Microsoft Academic Search

    Tran Dai Lam; Tran Vinh Hoang; Duong Tuan Quang; Jong Seung Kim

    2009-01-01

    The nanosized and surface-modified precipitated calcium carbonate (PCC) particles have been synthesized by carbonation reaction and used as reinforcing filler for preparing polypropylene (PP) composites. Both a crystallization inhibitor (sodium tripolyphosphate, TPP) and an organic surface modifier (stearic acid) were used to get narrow size distribution, uniform shape and nanometer size. The comprehensive results of morphological and mechanical analyses on

  11. Extracellular matrix production and calcium carbonate precipitation by coral cells in vitro

    E-print Network

    Extracellular matrix production and calcium carbonate precipitation by coral cells in vitro Yael), which facilitates controlled deposition of a calcium carbonate skeleton; and (iii) the calcium carbonate to nematocysts, mucous glands, and sensory or nerve cells (2, 3). Many corals also precipitate calcium carbonate

  12. Crucibleless crystal growth and Radioluminescence study of calcium tungstate single crystal fiber

    NASA Astrophysics Data System (ADS)

    Silva, M. S.; Jesus, L. M.; Barbosa, L. B.; Ardila, D. R.; Andreeta, J. P.; Silva, R. S.

    2014-11-01

    In this article, single phase and high optical quality scheelite calcium tungstate single crystal fibers were grown by using the crucibleless laser heated pedestal growth technique. The as-synthesized calcium tungstate powders used for shaping seed and feed rods were investigated by X-ray diffraction technique. As-grown crystals were studied by Raman spectroscopy and Radioluminescence measurements. The results indicate that in both two cases, calcined powder and single crystal fiber, only the expected scheelite CaWO4 phase was observed. It was verified large homogeneity in the crystal composition, without the presence of secondary phases. The Radioluminescence spectra of the as-grown single crystal fibers are in agreement with that present in Literature for bulk single crystals, presented a single emission band centered at 420 nm when irradiated with ?-rays.

  13. Accelerated carbonation of Friedel's salt in calcium aluminate cement paste

    Microsoft Academic Search

    S. Goñi; A. Guerrero

    2003-01-01

    The stability of Friedel's salt with respect to carbonation has been studied in calcium aluminate cement (CAC) pastes containing NaCl (3% of Cl? by weight of cement). Carbonation was carried out on a powdered sample in flowing 5% CO2 gas at 65% relative humidity to accelerate the process. At an intermediate carbonation step, a part of the sample was washed

  14. Ris-R-1143(EN) Modelling Calcium Carbonate Deposition

    E-print Network

    Risø-R-1143(EN) CRACK2 - Modelling Calcium Carbonate Deposition from Bicarbonate Solution in Cracks of bicarbonate solution in a crack connecting the ends of a row of such columns. The cementitious material is simulated as calcium hydroxide mixed with inert material but with sodium hydroxide dissolved in the pore

  15. RECOVERY OF CALCIUM CARBONATE AND SULFUR FROM FGD SCRUBBER WASTE

    EPA Science Inventory

    The report gives results of a demonstration of key process steps in the proprietary Kel-S process for recovering calcium carbonate and sulfur from lime/limestone flue gas desulfurization (FGD) scrubber waste. The steps are: reduction of the waste to calcium sulfide (using coal as...

  16. Behaviour of calcium carbonate in sea water

    USGS Publications Warehouse

    Cloud, P.E., Jr.

    1962-01-01

    Anomalies in the behaviour of calcium carbonate in natural solutions diminish when considered in context. Best values found by traditional oceanographie methods for the apparent solubility product constant K'CaCO3 in sea water at atmospheric pressure are consistent mineralogically-at 36 parts per thousand salinity and T-25??C, K'aragonlte is estimated as 1.12 ?? 10-6 and K'calcite as 0.61 ?? 10-6. At 30??C the corresponding values are 0.98 ?? 10-6 for aragonite and 0.53 ?? 10-6 for calcite. Because the K' computations do not compensate for ionic activity, however, they cannot give thermodynamically satisfactory results. It is of interest, therefore, that approximate methods and information now available permit the estimation from the same basic data of an activity product constant KCaCO3 close to that found in solutions to which Debye-Hu??ckel theory applies. Such methods indicate approximate Karagonite 7.8 ?? 10-9 for surface sea water at 29??C; Kcalcite would be proportionately lower. Field data and experimental results indicate that the mineralogy of precipitated CaCO3 depends primarily on degree of supersaturation, thus also on kinetic or biologic factors that facilitate or inhibit a high degree of supersaturation. The shallow, generally hypersaline bank waters west of Andros Island yield aragonitic sediments with O18 O16 ratios that imply precipitation mainly during the warmer months, when the combination of a high rate of evaporation, increasing salinity (and ionic strength), maximal temperatures and photosynthetic removal of CO2 result in high apparent supersaturation. The usual precipitate from solutions of low ionic strength is calcite, except where the aragonite level of supersaturation is reached as a result of diffusion phenomena (e.g. dripstones), gradual and marked evaporation, or biologic intervention. Published data also suggest the possibility of distinct chemical milieus for crystallographic variations in skeletal calcium carbonate. It appears that in nature aragonite precipitates from solutions that are supersaturated with respect to both calcite and aragonite and calcite between saturation levels for the two species. Such a relation is consistent with Ostwald's rule of successive reactions. Aragonitc of marine origin persists in contact with supersaturated interstitial solutions at ordinary temperature and pressure. Conversion to calcite follows transfer to solutions undersaturated with respect to aragonite or upon exposure to the moist atmosphere. ?? 1962.

  17. Thermal breakdown of calcium carbonate and constraints on its use as a biomarker

    NASA Astrophysics Data System (ADS)

    Thompson, Stephen P.; Parker, Julia E.; Tang, Chiu C.

    2014-02-01

    Observed differences in the thermal behaviour of calcium carbonates of biogenic and abiogenic origin (phase transformation and breakdown temperatures) are widely cited as potential biomarkers for whether life once existed on Mars. Although seemingly compelling, there has been no systematic investigation into the physical mechanism behind these apparent differences and therefore no direct proof that they are uniquely diagnostic of a biogenic versus abiogenic formation. In this paper we present a laboratory investigation into the thermal behaviour of two high purity calcium carbonates, one of which was produced in the presence of an amino acid as a biomimetic carbonate. In situ synchrotron X-ray powder diffraction measurements show the aragonite-to-calcite phase transition and calcite-to-oxide breakdown temperatures are significantly lower in the biomimetic carbonate. The observed thermal differences closely match reported differences between biogenic and geological abiogenic carbonates. The biomimetic carbonate exhibits a modified crystal morphology, with a highly strained internal crystal lattice, similar to biogenic carbonate structures. Since biogenic carbonates are formed in the presence of organic macromolecules such as amino acids, the induced microstrain appears to be the defining common factor as it adds an additional energy term to the carbonate lattice energy, which lowers the activation energy required for structural transformation or decomposition. Although produced via biomimetic means, the carbonate investigated here is nevertheless abiogenic in origin and we propose that given suitable localised conditions such as pooled water and a supply of organic molecules, naturally occurring biomimetic carbonates could have similarly formed on the martian surface and could therefore exhibit the same thermal characteristics as biogenic carbonate. Thus as a limiting case - without other supporting observations - the thermal behaviour of martian calcium carbonate might only be a marker for a pre-biotic organic chemistry having once been present rather than living organisms.

  18. Morphologies and elemental compositions of calcium crystals in phyllodes and branchlets of Acacia robeorum (Leguminosae: Mimosoideae)

    PubMed Central

    He, Honghua; Bleby, Timothy M.; Veneklaas, Erik J.; Lambers, Hans; Kuo, John

    2012-01-01

    Background and Aims Formation of calcium oxalate crystals is common in the plant kingdom, but biogenic formation of calcium sulfate crystals in plants is rare. We investigated the morphologies and elemental compositions of crystals found in phyllodes and branchlets of Acacia robeorum, a desert shrub of north-western Australia. Methods Morphologies of crystals in phyllodes and branchlets of A. robeorum were studied using scanning electron microscopy (SEM), and elemental compositions of the crystals were identified by energy-dispersive X-ray spectroscopy. Distributional patterns of the crystals were studied using optical microscopy together with SEM. Key Results According to the elemental compositions, the crystals were classified into three groups: (1) calcium oxalate; (2) calcium sulfate, which is a possible mixture of calcium sulfate and calcium oxalate with calcium sulfate being the major component; and (3) calcium sulfate · magnesium oxalate, presumably mixtures of calcium sulfate, calcium oxalate, magnesium oxalate and silica. The crystals were of various morphologies, including prisms, raphides, styloids, druses, crystal sand, spheres and clusters. Both calcium oxalate and calcium sulfate crystals were observed in almost all tissues, including mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex; calcium sulfate · magnesium oxalate crystals were only found in mesophyll and parenchyma cells in phyllodes. Conclusions The formation of most crystals was biologically induced, as confirmed by studying the crystals formed in the phyllodes from seedlings grown in a glasshouse. The crystals may have functions in removing excess calcium, magnesium and sulfur, protecting the plants against herbivory, and detoxifying aluminium and heavy metals. PMID:22294477

  19. Decomposition kinetics study of AlOOH coated calcium carbonate

    Microsoft Academic Search

    Dalai Jin; Xiaojing Yu; Linhai Yue; Lina Wang

    2009-01-01

    AlOOH coated calcium carbonate was synthesized by a two-step chemical solution reaction. The phase and microstructure analysis were carried out by X-ray diffraction and scanning electron microscopy. Non-isothermal decomposition kinetics of the AlOOH coated calcium carbonate has been investigated on the basis of the TG–DTA analysis. The model-free and model fitting approaches were applied to the data for non-isothermal decomposition

  20. Preparation of monodispersed cubic calcium carbonate particles via precipitation reaction

    Microsoft Academic Search

    Bei Cheng; Ming Lei; Jiaguo Yu; Xiujian Zhao

    2004-01-01

    Monodispersed cubic calcium carbonate composite particles were prepared by the precipitation reaction of sodium carbonate with calcium chloride in water in the presence of polyacrylic acid (PAA) at 60–80 °C, and then characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and Differential Scanning Calorimetry-Thermogravimetry (DSC-TG). It was found from the above results that variations in the concentration of PAA

  1. DNA-mediated morphosynthesis of calcium carbonate particles

    Microsoft Academic Search

    Bei Cheng; Weiquan Cai; Jiaguo Yu

    2010-01-01

    Calcium carbonate microspheres with different surface structures were successfully prepared by the reaction of sodium carbonate with calcium chloride in the presence of deoxyribonucleic acid (DNA) at room temperature. The as-prepared products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TGA–DSC) and fourier-transform infrared spectrometry (FTIR). The effects

  2. ARTICLE Evolution Mechanism of Calcium Carbonate in Solution

    Microsoft Academic Search

    Ya-ping Guo; Hai-xiong Tang; Yu Zhou; De-chang Jia; Cong-qin Ning; Ya-jun Guo

    2010-01-01

    Calcium carbonate was synthesized in a CaCl2\\/NaCO3 mixed solution by using ethylenediaminetetraacetic acid (EDTA) as an additive. The thermodynamics and kinetics analyses indicate that although the driving force of amorphous calcium carbonate (ACC) precipitation is always less than that of calcite and vaterite precipitation, the nucleation rate of ACC is greater than that of calcite and vaterite at the initial

  3. 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. PMID:21336282

  4. Calcium Carbonate Formation by Genetically Engineered Inorganic Binding Peptides

    NASA Astrophysics Data System (ADS)

    Gresswell, Carolyn Gayle

    Understanding how organisms are capable of forming (synthesize, crystallize, and organize) solid minerals into complex architectures has been a fundamental question of biomimetic materials chemistry and biomineralization for decades. This study utilizes short peptides selected using a cell surface display library for the specific polymorphs of calcium carbonate, i.e., aragonite and calcite, to identify two sets of sequences which can then be used to examine their effects in the formation, crystal structure, morphology of the CaCO3 minerals. A procedure of counter selection, along with fluorescence microscopy (FM) characterization, was adapted to insure that the sequences on the cells were specific to their respective substrate, i.e., aragonite or calcite. From the resulting two sets of sequences selected, five distinct strong binders were identified with a variety of biochemical characteristics and synthesized for further study. Protein derived peptides, using the known sequences of the proteins that are associated with calcite or aragonite, were also designed using a bioinformatics-based similarity analysis of the two sets of binders. In particular, an aragonite binding protein segment, AP7, a protein found in nacre, was chosen for this design and the resulting effects of the designed peptides and the AP7 were examined. Specifically, the binding affinities of the selected and the protein derived peptides off the cells were then tested using FM; these studies resulted in different binding characteristics of the synthesized and cellular bound peptides. Two of the peptides that displayed strong binding on the cells bound to neither of the CaCO 3 substrates and both the high and low similarity protein-derived peptides bound to both polymorphs. However, two of the peptides were found to only bind to their respective polymorph showing; these results are significant in that with this study it is demonstrated that the designed peptides based on experimental library-based selection and sequence identification, can be designed to have recognition capability to a given crystal structure, specifically, in this case, of calcium carbonate. Calcite mineralization with the peptides produced vaterite when several of the peptides were used in the synthesis process, many having unique morphologies studied using scanning electron microscopy (SEM). The amount of vaterite crystal percentage in these biomineralized mixtures was calculated and it was found to be closely related to peptide concentration for the aragonite-binding peptides. In the aragonite mineralization experiments, a separate solid phase, namely, calcium nitrate hydrate, was produced for one of the peptides along with the other polymorphs of calcite carbonate (ie., aragonite, calcite and vaterite) in the solution in the form of a flat film. These biomineralization results are examined in the light of the effects of peptide sequences and their related solid-binding characteristics

  5. Calcium carbonate scaling kinetics determined from radiotracer experiments with calcium-47

    SciTech Connect

    Turner, C.W.; Smith, D.W. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada). Chalk River Labs.] [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada). Chalk River Labs.

    1998-02-01

    The deposition of calcium carbonate is one of the principal modes of fouling of the heat-transfer surface of a fresh-water-cooled heat exchanger. The deposition rate of calcium carbonate on a heat-transfer surface has been measured using a calcium-47 radiotracer and compared to the measured rate of thermal fouling. The crystalline phase of calcium carbonate that precipitates depends on the degree of supersaturation at the heat-transfer surface, with aragonite precipitating at higher supersaturations and calcite precipitating at lower supersaturations. Whereas the mass deposition rates were constant with time, the thermal fouling rates decreased throughout the course of each experiment as a result of densification of the deposit. It is proposed that the densification was driven by the temperature gradient across the deposit together with the retrograde solubility of calcium carbonate. The temperature dependence of the deposition rate yielded an activation energy of 79 {+-} 4 kJ/mol for the precipitation of calcium carbonate on a heat-transfer surface.

  6. Plant calcium oxalate crystal formation, function, and its impact on human health

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crystals of calcium oxalate have been observed among members from most taxonomic groups of photosynthetic organisms ranging from the smallest algae to the largest trees. The biological roles for calcium oxalate crystal formation in plant growth and development include high capacity calcium regulatio...

  7. 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

  8. Synthesis of calcium antimonate nano-crystals by the 18th dynasty Egyptian glassmakers

    NASA Astrophysics Data System (ADS)

    Lahlil, S.; Biron, I.; Cotte, M.; Susini, J.; Menguy, N.

    2010-01-01

    During the 18th Egyptian dynasty (1570-1292 B.C.), opaque white, blue and turquoise glasses were opacified by calcium antimonate crystals dispersed in a vitreous matrix. The technological processes as well as the antimony sources used to manufacture these crystals remain unknown. Our results shed a new light on glassmaking history: contrary to what was thought, we demonstrate that Egyptian glassmakers did not use in situ crystallization but first synthesized calcium antimonate opacifiers, which do not exist in nature, and then added them to a glass. Furthermore, using transmission electron microscopy (TEM) for the first time in the study of Egyptian opaque glasses, we show that these opacifiers were nano-crystals. Prior to this research, such a process for glassmaking has not been suggested for any kind of ancient opaque glass production. Studying various preparation methods for calcium antimonate, we propose that Egyptian craftsmen could have produced Ca2Sb2O7 by using mixtures of Sb2O3 or Sb2O5 with calcium carbonates (atomic ratio Sb/Ca=1) heat treated between 1000 and 1100°C. We developed an original strategy focused on the investigation of the crystals and the vitreous matrices using an appropriate suite of high-sensitivity and high-resolution micro- and nano-analytical techniques (scanning electron microscopy (SEM), X-ray diffraction (XRD), TEM). Synchrotron-based micro X-ray absorption near edge spectroscopy (?-XANES) proved to be very well suited to the selective measure of the antimony oxidation state in the vitreous matrix. This work is the starting point for a complete reassessment not only of ancient Egyptian glass studies but more generally of high-temperature technologies used throughout antiquity.

  9. Nanoporous Structure and Medium-Range Order in Synthetic Amorphous Calcium Carbonate

    SciTech Connect

    Goodwin, Andrew L.; Michel, F. Marc; Phillips, Brian L.; Keen, David A.; Dove, Martin T.; Reeder, Richard J. (SBU); (Cambridge); (Oxford); (RAL)

    2010-12-03

    We adopt a reverse Monte Carlo refinement approach, using experimental X-ray total scattering data, to develop a structure model for synthetic, hydrated amorphous calcium carbonate (ACC). The ACC is revealed to consist of a porous calcium-rich framework that supports interconnected channels containing water and carbonate molecules. The existence of a previously unrecognized nanometer-scale channel network suggests mechanisms of how additives can be accommodated within the structure and provide temporary stabilization, as well as influence the crystallization process. Moreover, while lacking long-range order, the calcium-rich framework in the ACC contains similar Ca packing density to that present in calcite, aragonite, and vaterite, yielding clues of how the amorphous material converts into the different crystalline forms. Our results provide a new starting point for advancing our understanding of biomineralization as well as the development of biomimetic approaches to next-generation materials synthesis.

  10. Isolation of Medicago truncatula Mutants Defective in Calcium Oxalate Crystal Formation1

    PubMed Central

    Nakata, Paul A.; McConn, Michele M.

    2000-01-01

    Plants accumulate crystals of calcium oxalate in a variety of shapes, sizes, amounts, and spatial locations. How and why many plants form crystals of calcium oxalate remain largely unknown. To gain insight into the regulatory mechanisms of crystal formation and function, we have initiated a mutant screen to identify the genetic determinants. Leaves from a chemically mutagenized Medicago truncatula population were visually screened for alterations in calcium oxalate crystal formation. Seven different classes of calcium oxalate defective mutants were identified that exhibited alterations in crystal nucleation, morphology, distribution and/or amount. Genetic analysis suggested that crystal formation is a complex process involving more than seven loci. Phenotypic analysis of a mutant that lacks crystals, cod 5, did not reveal any difference in plant growth and development compared with controls. This finding brings into question the hypothesized roles of calcium oxalate formation in supporting tissue structure and in regulating excess tissue calcium. PMID:11080287

  11. Surface modification of calcium carbonate: radical graft polymerization of vinyl monomers onto calcium carbonate surface initiated by azo groups introduced onto the surface

    Microsoft Academic Search

    Yukio Shirai; Kazuyo Seno; Takamitsu Da; Norio Tsubokawa

    1996-01-01

    —The preparation of calcium carbonate modified by 12-hydroxystearate groups and the grafting of polymers onto the surface by the polymerization of vinyl monomers initiated by azo groups introduced onto the surface were investigated. The preparation of calcium carbonate modified by 12-hydroxystearate was achieved by the reaction of calcium chloride with sodium carbonate containing a small amount of sodium 12-hydroxystearate. The

  12. Carbon nanotubes as liquid crystals.

    PubMed

    Zhang, Shanju; Kumar, Satish

    2008-09-01

    Carbon nanotubes are the best of known materials with a combination of excellent mechanical, electronic, and thermal properties. To fully exploit individual nanotube properties for various applications, the grand challenge is to fabricate macroscopic ordered nanotube assemblies. Liquid-crystalline behavior of the nanotubes provides a unique opportunity toward reaching this challenge. In this Review, the recent developments in this area are critically reviewed by discussing the strategies for fabricating liquid-crystalline phases, addressing the solution properties of liquid-crystalline suspensions, and exploiting the practical techniques of liquid-crystal routes to prepare macroscopic nanotube fibers and films. PMID:18752206

  13. Calcium Channels are Involved in Calcium Oxalate Crystal Formation in Specialized Cells of Pistia stratiotes L.

    PubMed Central

    VOLK, GAYLE M.; GOSS, LENORA J.; FRANCESCHI, VINCENT R.

    2004-01-01

    • Background and Aims Pistia stratiotes produces large amounts of calcium (Ca) oxalate crystals in specialized cells called crystal idioblasts. The potential involvement of Ca2+ channels in Ca oxalate crystal formation by crystal idioblasts was investigated. • Methods Anatomical, ultrastructural and physiological analyses were used on plants, fresh or fixed tissues, or protoplasts. Ca2+ uptake by protoplasts was measured with 45Ca2+, and the effect of Ca2+ channel blockers studied in intact plants. Labelled Ca2+ channel blockers and a channel protein antibody were used to determine if Ca2+ channels were associated with crystal idioblasts. • Key Results 45Ca2+ uptake was more than two orders of magnitude greater for crystal idioblast protoplasts than mesophyll protoplasts, and idioblast number increased when medium Ca was increased. Plants grown on media containing 1–50 µm of the Ca2+ channel blockers, isradipine, nifedipine or fluspirilene, showed almost complete inhibition of crystal formation. When fresh tissue sections were treated with the fluorescent dihydropyridine?type Ca2+ channel blocker, DM?Bodipy?DHP, crystal idioblasts were intensely labelled compared with surrounding mesophyll, and the label appeared to be associated with the plasma membrane and the endoplasmic reticulum, which is shown to be abundant in idioblasts. An antibody to a mammalian Ca2+ channel ?1 subunit recognized a single band in a microsomal protein fraction but not soluble protein fraction on western blots, and it selectively and heavily labelled developing crystal idioblasts in tissue sections. • Conclusions The results demonstrate that Ca oxalate crystal idioblasts are enriched, relative to mesophyll cells, in dihydropyridine?type Ca2+ channels and that the activity of these channels is important to transport and accumulation of Ca2+ required for crystal formation. PMID:15087302

  14. Influence of maleic acid copolymers on calcium orthophosphates crystallization at low temperature

    NASA Astrophysics Data System (ADS)

    Pelin, Irina M.; Popescu, Irina; Suflet, Dana M.; Aflori, Magdalena; Bulacovschi, Victor

    2013-08-01

    The goal of this study was to investigate the maleic acid copolymers role on calcium orthophosphates crystallization at low temperature. In this respect, two maleic acid copolymers with different structures [poly(sodium maleate-co-vinyl acetate) and poly(sodium maleate-co-methyl methacrylate)] were used. The syntheses of the calcium orthophosphates in the absence and in the presence of the copolymers were performed through the wet chemical method using calcium nitrate, ammonium dihydrogen phosphate and ammonium hydroxide as reactants. The syntheses were monitored in situ by potentiometric and conductometric measurements. To ensure the transformation of less thermodynamically stable calcium orthophosphates into more stable forms, the samples were aged 30 days in mother solutions, at room temperature. The presence of the copolymers in the final products was evidenced by FTIR spectroscopy and thermogravimetric analysis. Scanning and transmission electron microscopy and laser light scattering measurements gave information about the composites morphology and the size of the formed structures. X-ray diffraction evidenced that, as a function of comonomer structure and of copolymer concentration, the products could contain hydroxyapatite with low crystallinity, calcium-deficient or carbonated hydroxyapatite. At high concentration of poly(sodium maleate-co-methyl methacrylate) the transformation of brushite into apatitic structures was inhibited.

  15. 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

  16. Waste oil shale ash as a novel source of calcium for precipitated calcium carbonate: carbonation mechanism, modeling, and product characterization.

    PubMed

    Velts, O; Uibu, M; Kallas, J; Kuusik, R

    2011-11-15

    In this paper, a method for converting lime-containing oil shale waste ash into precipitated calcium carbonate (PCC), a valuable commodity is elucidated. The mechanism of ash leachates carbonation was experimentally investigated in a stirred semi-batch barboter-type reactor by varying the CO(2) partial pressure, gas flow rate, and agitation intensity. A consistent set of model equations and physical-chemical parameters is proposed to describe the CaCO(3) precipitation process from oil shale ash leachates of complex composition. The model enables the simulation of reactive species (Ca(2+), CaCO(3), SO(4)(2-), CaSO(4), OH(-), CO(2), HCO(3)(-), H(+), CO(3)(2-)) concentration profiles in the liquid, gas, and solid phases as well as prediction of the PCC formation rate. The presence of CaSO(4) in the product may also be evaluated and used to assess the purity of the PCC product. A detailed characterization of the PCC precipitates crystallized from oil shale ash leachates is also provided. High brightness PCC (containing up to ? 96% CaCO(3)) with mean particle sizes ranging from 4 to 10 ?m and controllable morphology (such as rhombohedral calcite or coexisting calcite and spherical vaterite phases) was obtained under the conditions studied. PMID:21872990

  17. Effect of calcium carbonate saturation of seawater on coral calcification

    Microsoft Academic Search

    J.-P. Gattuso; M. Frankignoulle; I. Bourge; S. Romaine; R. W. Buddemeier

    1998-01-01

    The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata

  18. Protein adsorption at calcium oxalate monohydrate crystal surfaces.

    NASA Astrophysics Data System (ADS)

    Wesson, J.; Sheng, X.; Rimer, J.; Jung, T.; Ward, M.

    2008-03-01

    Calcium oxalate monohydrate (COM) crystals are the dominant inorganic phase in most kidney stones, and kidney stones form as aggregates of COM crystals and organic material, principally proteins, but little is known about the molecular level events at COM surfaces that regulate COM aggregation. We have examined the influence of polyelectrolytes on the force of adhesion between chemically modified atomic force microscopy (AFM) tips and selected COM crystal faces in saturated solution. In general, we found that polyanions bind to COM surfaces and block adhesion of a carboxylate functionalized AFM tip, while polycations had no measureable effect on adhesion force under the same conditions. We did observe a unique absence of interaction between poly(glutamic acid) and the COM (100) face compared to other synthetic polyanions, and some native urinary protein structures also exhibited unique face selective interactions, suggesting that simple electrostatic models will not completely explain the data.

  19. Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment.

  20. 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

  1. Formation of a calcium phosphate-rich layer on absorbable calcium carbonate bone graft substitutes

    Microsoft Academic Search

    C. J. Damien; J. L. Ricci; P. Christel; H. Alexander; J.-L. Patat

    1994-01-01

    The use of natural coral as a bone graft substitute is common in Europe. However, the bone-coral bonding mechanism remains elusive. A rat subcutaneous model was used to demonstrate changes at the surface of resorbable calcium carbonate in the form of natural coral. Histological results indicated in vivo formation of a calcium phosphate (CaP)-rich layer on the surface of the

  2. Geometrically structured implants for cranial reconstruction made of biodegradable polyesters and calcium phosphate\\/calcium carbonate

    Microsoft Academic Search

    Carsten Schiller; Christian Rasche; Michael Wehmöller; Felix Beckmann; Harald Eufinger; Matthias Epple; Stephan Weihe

    2004-01-01

    The aim of this study was the development of a processing pathway for manufacturing of biodegradable skull implants with individual geometry. The implants on the basis of polylactide and calcium phosphate\\/calcium carbonate were prepared by a combination of hot pressing and gas foaming. On the inside, the implant consists of a macroporous and faster degradable material (poly(d,l-lactide)+CaCO3) to allow the

  3. A carbonate controlled-addition method for size-controlled calcium carbonate spheres by carboxylic acid-terminated poly(amidoamine) dendrimers

    Microsoft Academic Search

    Yuka Tanaka; Kensuke Naka; K Naka

    2010-01-01

    Size-controlled calcium carbonate particles were obtained using a ‘carbonate controlled-addition method’ with G0.5 poly(amidoamine) (PAMAM) dendrimer with carboxylate groups at the external surface. An aqueous ammonium carbonate solution was added to an aqueous solution of the dendrimer and CaCl2 at different time periods (3 min, 1 h or 24 h) and was stirred for 1 day. Both crystal phases obtained

  4. Drug loading into porous calcium carbonate microparticles by solvent evaporation.

    PubMed

    Preisig, Daniel; Haid, David; Varum, Felipe J O; Bravo, Roberto; Alles, Rainer; Huwyler, Jörg; Puchkov, Maxim

    2014-08-01

    Drug loading into porous carriers may improve drug release of poorly water-soluble drugs. However, the widely used impregnation method based on adsorption lacks reproducibility and efficiency for certain compounds. The aim of this study was to evaluate a drug-loading method based on solvent evaporation and crystallization, and to investigate the underlying drug-loading mechanisms. Functionalized calcium carbonate (FCC) microparticles and four drugs with different solubility and permeability properties were selected as model substances to investigate drug loading. Ibuprofen, nifedipine, losartan potassium, and metronidazole benzoate were dissolved in acetone or methanol. After dispersion of FCC, the solvent was removed under reduced pressure. For each model drug, a series of drug loads were produced ranging from 25% to 50% (w/w) in steps of 5% (w/w). Loading efficiency was qualitatively analyzed by scanning electron microscopy (SEM) using the presence of agglomerates and drug crystals as indicators of poor loading efficiency. The particles were further characterized by mercury porosimetry, specific surface area measurements, differential scanning calorimetry, and USP2 dissolution. Drug concentration was determined by HPLC. FCC-drug mixtures containing equivalent drug fractions but without specific loading strategy served as reference samples. SEM analysis revealed high efficiency of pore filling up to a drug load of 40% (w/w). Above this, agglomerates and separate crystals were significantly increased, indicating that the maximum capacity of drug loading was reached. Intraparticle porosity and specific surface area were decreased after drug loading because of pore filling and crystallization on the pore surface. HPLC quantification of drugs taken up by FCC showed only minor drug loss. Dissolution rate of FCC loaded with metronidazole benzoate and nifedipine was faster than the corresponding FCC-drug mixtures, mainly due to surface enlargement, because only small fractions of amorphous drug (12.5%, w/w, and 8.9%, w/w, respectively) were found by thermal analysis. Combination of qualitative SEM analysis and HPLC quantification was sufficient to proof the feasibility of the solvent-evaporation method for the loading of various drugs into FCC. Mechanistic investigation revealed that a high specific surface area of the carrier is required to facilitate heterogeneous nucleation, and large pore sizes (up to 1 ?m) are beneficial to reduce crystallization pressures and allow drug deposition within the pores. The solvent-evaporation method allows precise drug loading and appears to be suitable for scale-up. PMID:24568926

  5. Crystal structure of calcium dodecin (Rv0379), from Mycobacterium tuberculosis with a unique calcium-binding site

    SciTech Connect

    Arockiasamy, Arulandu; Aggarwal, Anup; Savva, Christos G.; Holzenburg, Andreas; Sacchettini, James C. (TAM)

    2011-09-28

    In eukaryotes, calcium-binding proteins play a pivotal role in diverse cellular processes, and recent findings suggest similar roles for bacterial proteins at different stages in their life cycle. Here, we report the crystal structure of calcium dodecin, Rv0379, from Mycobacterium tuberculosis with a dodecameric oligomeric assembly and a unique calcium-binding motif. Structure and sequence analysis were used to identify orthologs of Rv0379 with different ligand-binding specificity

  6. 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.

  7. Dissolution of steelmaking slags in acetic acid for precipitated calcium carbonate production

    Microsoft Academic Search

    Sebastian Teir; Sanni Eloneva; Carl-Johan Fogelholm; Ron Zevenhoven

    2007-01-01

    A promising option for long-term storage of CO2 is to fixate carbon dioxide as magnesium- and calcium carbonates. Slags from iron and steel works are potential raw materials for carbonation due to their high contents of calcium silicates. Precipitated calcium carbonate (PCC) is used as filler and coating materials in paper. If slag could be used instead of limestone for

  8. 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

  9. Ion chromatography detection of fluoride in calcium carbonate.

    PubMed

    Lefler, Jamie E; Ivey, Michelle M

    2011-09-01

    Fluoride in aquatic systems is increasing due to anthropogenic pollution, but little is known about how this fluoride affects organisms that live in and around aquatic habitats. Fluoride can bioaccumulate in structures comprised of calcium carbonate, such as shells and skeletons of both freshwater and saltwater species as diverse as snails, corals, and coccolithophorid algae. In this article, ion chromatography (IC) techniques are developed to detect and quantify fluoride in a matrix of calcium carbonate. Solid samples are dissolved in hydrochloric acid, pretreated to remove the majority of the chloride ions, and then analyzed using IC. With these methods, the 3? limit of detection is 0.2 mg of fluoride/kg of calcium carbonate. PMID:21859530

  10. Crystallization of calcium oxalates is controlled by molecular hydrophilicity and specific polyanion-crystal interactions.

    PubMed

    Grohe, Bernd; Taller, Adam; Vincent, Peter L; Tieu, Long D; Rogers, Kem A; Heiss, Alexander; Sørensen, Esben S; Mittler, Silvia; Goldberg, Harvey A; Hunter, Graeme K

    2009-10-01

    To gain more insight into protein structure-function relationships that govern ectopic biomineralization processes in kidney stone formation, we have studied the ability of urinary proteins (Tamm-Horsfall protein, osteopontin (OPN), prothrombin fragment 1 (PTF1), bikunin, lysozyme, albumin, fetuin-A), and model compounds (a bikunin fragment, recombinant-, milk-, bone osteopontin, poly-L-aspartic acid (poly asp), poly-L-glutamic acid (poly glu)) in modulating precipitation reactions of kidney stone-related calcium oxalate mono- and dihydrates (COM, COD). Combining scanning confocal microscopy and fluorescence imaging, we determined the crystal faces of COM with which these polypeptides interact; using scanning electron microscopy, we characterized their effects on crystal habits and precipitated volumes. Our findings demonstrate that polypeptide adsorption to COM crystals is dictated first by the polypeptide's affinity for the crystal followed by its preference for a crystal face: basic and relatively hydrophobic macromolecules show no adsorption, while acidic and more hydrophilic polypeptides adsorb either nonspecifically to all faces of COM or preferentially to {100}/{121} edges and {100} faces. However, investigating calcium oxalates grown in the presence of these polypeptides showed that some acidic proteins that adsorb to crystals do not affect crystallization, even if present in excess of physiological concentrations. These proteins (albumin, bikunin, PTF1, recombinant OPN) have estimated total hydrophilicities from 200 to 850 kJ/mol and net negative charges from -9 to -35, perhaps representing a "window" in which proteins adsorb and coat urinary crystals (support of excretion) without affecting crystallization. Strongest effects on crystallization were observed for polypeptides that are either highly hydrophilic (>950 kJ/mol) and highly carboxylated (poly asp, poly glu), or else highly hydrophilic and highly phosphorylated (native OPN isoforms), suggesting that highly hydrophilic proteins strongly affect precipitation processes in the urinary tract. Therefore, the level of hydrophilicity and net charge is a critical factor in the ability of polypeptides to affect crystallization and to regulate biomineralization processes. PMID:19725562

  11. Isolation of mucin from human hepatic bile and its induced effects on precipitation of cholesterol and calcium carbonate in vitro

    Microsoft Academic Search

    Toru Yamasaki; Kazuo Chijiiwa; Masahiko Endo

    1993-01-01

    biliary mucin was isolated from human hepatic bile, and its induced effects on the appearance time of cholesterol monohydrate crystals (nucleation time) and on the precipitation of calcium carbonate were studiedin vitro to examine the possible significance of mucin for ductular gallstone formation. Mucin was isolated by gel filtration on Sepharose CL-4B and a subsequent CsCl density gradient ultracentrifugation. Mucin

  12. Growth and thermal behavior of mixed crystals of calcium cadmium tartrate in silica gels

    Microsoft Academic Search

    D. K. Sawant; H. M. Patil; D. S. Bhavsar; J. H. Patil; K. D. Girase

    In this study, calcium cadmium tartrate single crystals were grown in silica gel at ambient temperature. Effects of various\\u000a parameters like gel pH, gel aging, gel density, and concentration of reactants on the growth of these crystals were studied.\\u000a Crystals having different morphologies and habits were obtained. Transparent, diamond-like pyramidal-shaped crystals of calcium\\u000a cadmium tartrate were obtained. Some of the

  13. A critical analysis of calcium carbonate mesocrystals

    NASA Astrophysics Data System (ADS)

    Kim, Yi-Yeoun; Schenk, Anna S.; Ihli, Johannes; Kulak, Alex N.; Hetherington, Nicola B. J.; Tang, Chiu C.; Schmahl, Wolfgang W.; Griesshaber, Erika; Hyett, Geoffrey; Meldrum, Fiona C.

    2014-07-01

    The term mesocrystal has been widely used to describe crystals that form by oriented assembly, and that exhibit nanoparticle substructures. Using calcite crystals co-precipitated with polymers as a suitable test case, this article looks critically at the concept of mesocrystals. Here we demonstrate that the data commonly used to assign mesocrystal structure may be frequently misinterpreted, and that these calcite/polymer crystals do not have nanoparticle substructures. Although morphologies suggest the presence of nanoparticles, these are only present on the crystal surface. High surface areas are only recorded for crystals freshly removed from solution and are again attributed to a thin shell of nanoparticles on a solid calcite core. Line broadening in powder X-ray diffraction spectra is due to lattice strain only, precluding the existence of a nanoparticle sub-structure. Finally, study of the formation mechanism provides no evidence for crystalline precursor particles. A re-evaluation of existing literature on some mesocrystals may therefore be required.

  14. Were kinetics of Archean calcium carbonate precipitation related to oxygen concentration?

    NASA Technical Reports Server (NTRS)

    Sumner, D. Y.; Grotzinger, J. P.

    1996-01-01

    Archean carbonates commonly contain decimetre- to metre-thick beds consisting entirely of fibrous calcite and neomorphosed fibrous aragonite that precipitated in situ on the sea floor. The fact that such thick accumulations of precipitated carbonate are rare in younger marine carbonates suggests an important change in the modes of calcium carbonate precipitation through time. Kinetics of carbonate precipitation depend on the concentration of inhibitors to precipitation that reduce crystallization rates and crystal nuclei formation, leading to kinetic maintenance of supersaturated solutions. Inhibitors also affect carbonate textures by limiting micrite precipitation and promoting growth of older carbonate crystals on the sea floor. Fe2+, a strong calcite-precipitation inhibitor, is thought to have been present at relatively high concentrations in Archean seawater because oxygen concentrations were low. The rise in oxygen concentration at 2.2-1.9 Ga led to the removal of Fe2+ from seawater and resulted in a shift from Archean facies, which commonly include precipitated beds, to Proterozoic facies, which contain more micritic sediment and only rare precipitated beds.

  15. CRYSTALLIZATION OF CALCIUM PHOSPHATE ORIENTED BY SELF-ASSEMBLING DIBLOCK COPOLYMERS,

    E-print Network

    Amrhein, Valentin

    CRYSTALLIZATION OF CALCIUM PHOSPHATE ORIENTED BY SELF-ASSEMBLING DIBLOCK COPOLYMERS, IN SOLUTION. MINERALIZATION OF CALCIUM PHOSPHATE IN PRESENCE OF DHBC 28 B. AMPHIPHILIC POLY(ETHYLENE OXIDE)-BLOCK-POLY(VALEROLACTONE) DIBLOCK COPOLYMERS AS TEMPLATE FOR CALCIUM PHOSPHATE MINERALIZATION 30 1. SELF-ASSEMBLY IN AQUEOUS

  16. Formation of hollow bone-like morphology of calcium carbonate on surfactant/polymer templates

    NASA Astrophysics Data System (ADS)

    Mantilaka, M. M. M. G. P. G.; Pitawala, H. M. T. G. A.; Rajapakse, R. M. G.; Karunaratne, D. G. G. P.; Upul Wijayantha, K. G.

    2014-04-01

    Novel hollow, bone-like structures of Precipitated Calcium Carbonate (PCC) are fabricated, for the first time, starting from naturally occurring dolomite. The hollow, bone-like structures are prepared by precipitating calcium carbonate on self-assembled poly(acrylic acid)/cetyltrimethylammonium chloride (PAA/CTAC) template. Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Field Emission Scanning Electron Microscopic (FE-SEM) studies reveal that the bone-like structure is composed of Amorphous Calcium Carbonate (ACC) nanoparticles in the center and calcite nanoparticles at the edges. Bone-like PCC particles are in particle length of 2-3 ?m and particle width of 1 ?m. The internal hollow structures of bone-like particles are observed from TEM images. As identified by FE-SEM images, the bone-like structure has been formed through the crystal growth of initially formed ACC nanoparticles. The ACC particles are stabilized in the center while the calcite crystals have been grown from the ACC toward the edges of the structure to form a bone-like morphology. We also propose a possible mechanism for the formation of hollow bone-like PCC in this study. The fabricated hollow, bone-like PCC has potential applications in the preparation of release systems such as drugs, cosmetics and pigments.

  17. The effect of organic pigment on the grinding of calcium carbonate

    Microsoft Academic Search

    N. Kawashima; F. A. Loon; K. Meguro

    1978-01-01

    Summary Mixtures ofß-copper phthalocyanine-calcium carbonate, and?-quinacridone-calcium carbonate were ground together in various proportions, and the surface properties of the ground specimens were investigated at various grinding times by means of X-ray diffraction analysis, electron micrography, and specific surface area measurement. The addition of sufficient amounts of organic pigment to calcium carbonate retarded the calcite-aragonite transition of calcium carbonate. This was

  18. Crystal growth of calcite from calcium bicarbonate solutions at constant PCO2 and 25??C: a test of a calcite dissolution model

    USGS Publications Warehouse

    Reddy, M.M.; Plummer, L.N.; Busenberg, E.

    1981-01-01

    A highly reproducible seeded growth technique was used to study calcite crystallization from calcium bicarbonate solutions at 25??C and fixed carbon dioxide partial pressures between 0.03 and 0.3 atm. The results are not consistent with empirical crystallization models that have successfully described calcite growth at low PCO2 (< 10-3 atm). Good agreement was found between observed crystallization rates and those calculated from the calcite dissolution rate law and mechanism proposed by Plummer et al. (1978). ?? 1981.

  19. THE ROLE OF CALCIUM OXALATE CRYSTALS IN MEDICAGO TRUNCATULA DEFENSE AGAINST CHEWING INSECTS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate crystals are the most common insoluble mineral found in plants and can appear in different sizes and shapes. Functions proposed for the crystals include roles in ion balance, tissue support, detoxification, and in light-gathering and -reflection. We use calcium oxalate defective (cod...

  20. Biologically mediated dissolution of calcium carbonate above the chemical lysocline?

    Microsoft Academic Search

    J. D. Milliman; P. J. Troy; W. M. Balch; A. K. Adams; Y.-H. Li; F. T. Mackenzie

    1999-01-01

    We find a diverse but increasing amount of evidence to suggest considerable dissolution of calcium carbonate, perhaps as much as 60–80%, in the upper 500–1000m of the ocean, well above the chemical lysocline. The same biological processes that promote the rapid settling of carbonate particles (i.e. ingestion, digestion and egestion by zooplankton) as well as biologically mediated processes within flocculates

  1. Effect of amplitude and frequency of ultrasonic irradiation on morphological characteristics control of calcium carbonate

    Microsoft Academic Search

    Yoshiyuki Kojima; Kohei Yamaguchi; Nobuyuki Nishimiya

    2010-01-01

    We have previously reported on the morphological control of calcium carbonate by changing synthetic conditions such as temperature, pH and degree of supersaturation in liquid reaction. The present study reports the effect of amplitude and frequency of ultrasonic irradiation on the particle size of calcium carbonate using a horn type ultrasonic apparatus at two different frequencies. The calcium carbonate precipitated

  2. A model for calcium carbonate neutralization in the presence of armoring

    E-print Network

    Primicerio, Mario

    A model for calcium carbonate neutralization in the presence of armoring L. Fusia , M. Primicerioa for the reaction between calcium carbonate (CaCO3) and a solution containing sulfuric acid (H2SO4). We assume system and where the neutralizing agent is calcium carbonate (see [3], [4], [5]). These mod- els have

  3. Concentrations de carbonate de calcium sur les parois des hyphes mycliens

    E-print Network

    Boyer, Edmond

    Concentrations de carbonate de calcium sur les parois des hyphes mycéliens Gabriel CALLOT, Daniel possibilité de formation de carbonate de calcium sur les parois des filaments mycéliens. Parallèlement à ces, minéralogenèse. SUMMARY Concentration of calcium carbonate on the walls of fungal hyphae. The structure

  4. Biomimetic Synthesis of Macroscopic-Scale Calcium Carbonate Thin Films. Evidence for a Multistep Assembly Process

    E-print Network

    Aksay, Ilhan A.

    Biomimetic Synthesis of Macroscopic-Scale Calcium Carbonate Thin Films. Evidence for a Multistep growth modification and cessation, and so on. Highly ordered calcium carbonate lamellae formed have synthesized macroscopic and continuous calcium carbonate thin films with thickness ranging from 0

  5. Are environmental conditions recorded by the organic matrices associated with precipitated calcium carbonate in cyanobacterial microbialites?

    E-print Network

    Paris-Sud XI, Université de

    calcium carbonate in cyanobacterial microbialites? P. GAUTRET 1 , R. DE WIT 2 , G. CAMOIN 3 AND S. GOLUBIC acid composition of organic matrices associated with calcium carbonate precipitates in microbialites Caledonia (Nouméa lagoon) and French Polynesia (Tikehau atoll). Calcium carbonate precipitation

  6. Possible overestimation of shallow-depth calcium carbonate dissolution in the ocean

    E-print Network

    Follows, Mick

    Possible overestimation of shallow-depth calcium carbonate dissolution in the ocean K. Friis,1,2 R calcium carbonate (TA*) above the saturation horizon cannot be unambiguously interpreted in terms of local and biogeochemistry with explicit representation of the formation and dissolution of calcium carbonate. In particular

  7. Dissolution Kinetics of Calcium Carbonate Minerals A.V. Subhas1

    E-print Network

    Simon, Emmanuel

    Dissolution Kinetics of Calcium Carbonate Minerals A.V. Subhas1 *, N.E. Rollins2 , W. Berelson2 , J@gps.caltech.edu We present a novel measurement of the dissolution kinetics of calcium carbonate minerals in seawater. These experiments significantly impact our understanding of calcium carbonate response to ocean acidification, water

  8. The influence of kinetics on the oxygen isotope composition of calcium carbonate

    E-print Network

    Watkins, Jim

    The influence of kinetics on the oxygen isotope composition of calcium carbonate James M. Watkins a and calcium carbonate. Although oxygen isotope separation is expected on theoretical grounds, the temperature on equilibrium fractionation of oxygen isotopes between calcium carbonate and water. Equili- brium oxygen isotope

  9. Influence of some polysaccharides on the production of calcium carbonate filler particles

    Microsoft Academic Search

    Jasminka Kontrec; Damir Kralj; Ljerka Brecevic; Giuseppe Falini

    2008-01-01

    The influence of different water-soluble polysaccharides, dextrans (cationic, anionic and non-ionic) and soluble starch, on the precipitation of calcium carbonate, has been investigated in the model system in which calcium hydroxide and carbonic acid were reactants. In the absence of additives, the formation of metastable phases, vaterite and amorphous calcium carbonate is observed at the early stage of the process,

  10. A cell to study in situ electrocrystallization of calcium carbonate

    Microsoft Academic Search

    M. Euvrard; C Filiatre; E Crausaz

    2000-01-01

    In order to observe in real time and in situ the electrocrystallization of calcium carbonate, a new method using an assessment of the oxygen reduction reaction has been developed. The experimental assembly is composed of an electrochemical cell and an optical-video set-up. The specific features of the cell are: availability of an electrode polarization control, enabling the use of any

  11. Calcium Carbonate Production, Coral Reef Growth, and Sea Level Change

    Microsoft Academic Search

    S. V. Smith; D. W. Kinsey

    1976-01-01

    Shallow, seaward portions of modern coral reefs produce about 4 kilograms of calcium carbonate per square meter per year, and protected areas produce about 0.8 kilogram per square meter per year. The difference is probably largely a function of water motion. The more rapid rate, equivalent to a maximum vertical accretion of 3 to 5 millimeters per year, places an

  12. Porphyrin Amphiphiles as Templates for the Nucleation of Calcium Carbonate

    E-print Network

    Aksay, Ilhan A.

    Porphyrin Amphiphiles as Templates for the Nucleation of Calcium Carbonate Joydeep Lahiri amphiphiles.4-6 Model studies with small amphiphilic molecules at compressed Langmuir interfaces, pioneered associated with protein templates remain unknown at the molecular level. We have synthesized amphiphilic

  13. Ranitidine reduces phosphate binding in dialysis patients receiving calcium carbonate

    Microsoft Academic Search

    C. C. Tan; P. N. Harden; R. S. C. Rodger; P. A. Rowe; R. J. Spooner; B. J. R. Junor; J. D. Briggs

    Background. In a previous controlled study we showed that ranitidine significantly reduced the phosphate binding of aluminium hydroxide in patients with renal failure, probably by increasing intragastric pH. Methods. In this study we have investigated the effect of ranitidine on the phosphate binding of calcium carbonate in fifteen dialysis patients. Ranitidine 300 mg or a placebo tablet was taken before

  14. Reactive surface treatment for calcium carbonate filler in polypropylene

    Microsoft Academic Search

    Arunee Tabtiang; Richard Venables

    1998-01-01

    Calcium carbonate has been modified with three surface modifying systems based upon stearic acid, acrylic acid and a reactive coating comprising acrylic acid with dicumyl peroxide through dry blending. Polypropylene homopolymer was compounded with the coated and uncoated fillers (0 to 65 wt%) through twin screw extrusion. Infrared and extraction investigations showed that the acrylic acid coatings reacted extensively with

  15. CALCIUM OXALATE CRYSTAL FORMATION IS NOT ESSENTIAL FOR GROWTH OF MEDICAGO TRUNCATULA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plants invest a considerable amount of resources and energy into the formation of calcium oxalate crystals. A number of roles for crystal formation in plant growth and development have been assigned based on the prevalence of crystals, their spatial distribution, and the variety of crystal shapes. ...

  16. Coupled moisture—carbon dioxide–calcium transfer model for carbonation of concrete

    Microsoft Academic Search

    B. Bary; A. Sellier

    2004-01-01

    The carbonation mechanisms of concrete are analyzed in this paper, accounting for evolutions of relative humidity in the porous material. The model is based on macroscopic mass balance equations for the water, the carbon dioxide contained in the gaseous phase and the calcium contained in the pore solution, which are supposed to completely define the problem of atmospheric carbonation in

  17. CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTACTORS

    EPA Science Inventory

    The rate of carbonate mineral dissolution from limestone was studied using a rotating disk apparatus and samples of limestone of varied composition. The purpose of this study was to determine the effect of limestone composition on the kinetics of carbonate mineral dissolution. Th...

  18. CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTRACTORS

    EPA Science Inventory

    The rate of carbonate mineral dissolution from limestone was studied using a rotating disk apparatus and samples of limestone of varied composition. he purpose of this study was to determine the effect of limestone composition on the kinetics of carbonate mineral dissolution. he ...

  19. Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 Aresolution

    Microsoft Academic Search

    Chikashi Toyoshima; Masayoshi Nakasako; Hiromi Nomura; Haruo Ogawa

    2000-01-01

    Calcium ATPase is a member of the P-type ATPases that transport ions across the membrane against a concentration gradient. Here we have solved the crystal structure of the calcium ATPase of skeletal muscle sarcoplasmic reticulum (SERCA1a) at 2.6 A ? resolution with two calcium ions bound in the transmembrane domain, which comprises ten a-helices. The two calcium ions are located

  20. Production and accumulation of calcium carbonate in the ocean: Budget of a nonsteady state

    Microsoft Academic Search

    John D. Milliman

    1993-01-01

    The calcium carbonate budget in the ocean has become of great interest to geochemists, sedimentologists and paleoceanographers. The carbonate system represents only a small part of the global carbon cycle, but it is intimately related to atmospheric carbon dioxide. This paper discusses calcium carbonate production and accumulations in the present-day marine environment and over the past 25,000 years. The new

  1. Long-term effects of calcium carbonate and 2.5 mEq\\/liter calcium dialysate on mineral metabolism

    Microsoft Academic Search

    Eduardo Slatopolsky; Carol Weerts; Kathryn Norwood; Karla Giles; Patricia Fryer; Jane Finch; David Windus; James Delmez

    1989-01-01

    Long-term effects of calcium carbonate and 2.5 mEq\\/liter calcium dialysate on mineral metabolism. Many investigators have shown that calcium carbonate (CaCO3) is an effective phosphate binder which also prevents the potential disabling effects of aluminum (Al) accumulation. However, hypercalcemia may develop in a substantial numbers of patients. Thus, to control serum phosphate (PO4) and prevent hypercalcemia, we performed studies in

  2. Impact of calcium on struvite crystal size, shape and purity

    NASA Astrophysics Data System (ADS)

    Le Corre, Kristell S.; Valsami-Jones, Eugenia; Hobbs, Phil; Parsons, Simon A.

    2005-10-01

    Struvite precipitation occurs spontaneously in wastewater treatment plants under conditions that are influenced by many factors including concentration of Mg 2+, NH 4+, and PO 43- ions, pH, temperature, and mixing energy. These parameters are often difficult to control and as a result struvite generates problems of scale deposits in areas such as pipes and recirculation pumps. At the same time, struvite is considered as a potentially marketable product as an alternative fertiliser. For those two reasons, it has become important to study the principles of struvite precipitation, and to assess the parameters controlling struvite crystallisation. In the present work, the influence of Ca 2+ ions on the precipitation of struvite was investigated in aqueous solutions containing Mg 2+, NH 4+, and PO 43- ions in a molar ratio 1:2:2 at room temperature and constant pH. Different laboratory experiments have been used to assess the effects of Ca 2+ ions on size, shape, and purity of the crystals formed. Tools used include particle size analysis, X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDS). The experimental results showed that the presence of calcium in the media can affect significantly struvite crystal growth and the characteristics of the crystal produced.

  3. Molecular modulation of calcium oxalate crystallization by osteopontin and citrate

    PubMed Central

    Qiu, S. R.; Wierzbicki, A.; Orme, C. A.; Cody, A. M.; Hoyer, J. R.; Nancollas, G. H.; Zepeda, S.; De Yoreo, J. J.

    2004-01-01

    Calcium oxalate monohydrate (COM), which plays a functional role in plant physiology, is a source of chronic human disease, forming the major inorganic component of kidney stones. Understanding molecular mechanisms of biological control over COM crystallization is central to development of effective stone disease therapies and can help define general strategies for synthesizing biologically inspired materials. To date, research on COM modification by proteins and small molecules has not resolved the molecular-scale control mechanisms. Moreover, because proteins directing COM inhibition have been identified and sequenced, they provide a basis for general physiochemical investigations of biomineralization. Here, we report molecular-scale views of COM modulation by two urinary constituents, the protein osteopontin and citrate, a common therapeutic agent. Combining force microscopy with molecular modeling, we show that each controls growth habit and kinetics by pinning step motion on different faces through specific interactions in which both size and structure determine the effectiveness. Moreover, the results suggest potential for additive effects of simultaneous action by both modifiers to inhibit the overall growth of the crystal and demonstrate the utility of combining molecular imaging and modeling tools for understanding events underlying aberrant crystallization in disease. PMID:14766970

  4. A critical analysis of calcium carbonate mesocrystals

    PubMed Central

    Kim, Yi-Yeoun; Schenk, Anna S.; Ihli, Johannes; Kulak, Alex N.; Hetherington, Nicola B. J.; Tang, Chiu C.; Schmahl, Wolfgang W.; Griesshaber, Erika; Hyett, Geoffrey; Meldrum, Fiona C.

    2014-01-01

    The term mesocrystal has been widely used to describe crystals that form by oriented assembly, and that exhibit nanoparticle substructures. Using calcite crystals co-precipitated with polymers as a suitable test case, this article looks critically at the concept of mesocrystals. Here we demonstrate that the data commonly used to assign mesocrystal structure may be frequently misinterpreted, and that these calcite/polymer crystals do not have nanoparticle substructures. Although morphologies suggest the presence of nanoparticles, these are only present on the crystal surface. High surface areas are only recorded for crystals freshly removed from solution and are again attributed to a thin shell of nanoparticles on a solid calcite core. Line broadening in powder X-ray diffraction spectra is due to lattice strain only, precluding the existence of a nanoparticle sub-structure. Finally, study of the formation mechanism provides no evidence for crystalline precursor particles. A re-evaluation of existing literature on some mesocrystals may therefore be required. PMID:25014563

  5. Sulfate in foraminiferal calcium carbonate : investigating a potential proxy for sea water carbonate ion concentration

    E-print Network

    Berry, Jeffrey Nicholas

    1988-01-01

    The sulfur content of planktonic and benthic foraminifera was measured in specimens recovered from deep-sea sediment cores and individuals grown in culture. A new method for measuring sulfur in foraminiferal calcium carbonate ...

  6. Direct Observation of Completely Processed Calcium Carbonate Dust Particles

    SciTech Connect

    Laskin, Alexander; Iedema, Martin J.; Ichkovich, Aviad; Graber, Ellen R.; Taraniuk, Ilya; Rudich, Yinon

    2005-05-27

    This study presents, for the first time, field evidence of complete, irreversible processing of solid calcium carbonate (calcite)-containing particles and quantitative formation of liquid calcium nitrate particles apparently as a result of heterogeneous reaction of calcium carbonate-containing mineral dust particles with gaseous nitric acid. Formation of nitrates from individual calcite and sea salt particles was followed as a function of time in aerosol samples collected at Shoresh, Israel. Morphology and compositional changes of individual particles were observed using conventional scanning electron microscopy with energy dispersive analysis of X-rays (SEM/EDX) and computer controlled SEM/EDX. Environmental scanning electron microscopy (ESEM) was utilized to determine and demonstrate the hygroscopic behavior of calcium nitrate particles found in some of the samples. Calcium nitrate particles are exceptionally hygroscopic and deliquesce even at very low relative humidity (RH) of 9 -11% which is lower than typical atmospheric environments. Transformation of non-hygroscopic dry mineral dust particles into hygroscopic wet aerosol may have substantial impacts on light scattering properties, the ability to modify clouds and heterogeneous chemistry.

  7. Dissolution kinetics of calcium carbonate in sea water: VI. The near-equilibrium dissolution kinetics of calcium carbonate-rich deep sea sediments

    Microsoft Academic Search

    1978-01-01

    The dissolution kinetics of calcium carbonate from calcium carbonate-rich deep-sea sediments collected in the Indian, Pacific, and Atlantic Oceans were studied using a pH-stat technique in natural ocean and pore water. Sediments from different localities have different reaction orders and rate constants. The rate of dissolution per gram of calcium carbonate changes with the extent of dissolution, and different size

  8. Accelerated carbonation of Friedel's salt in calcium aluminate cement paste

    SciTech Connect

    Goni, S.; Guerrero, A

    2003-01-01

    The stability of Friedel's salt with respect to carbonation has been studied in calcium aluminate cement (CAC) pastes containing NaCl (3% of Cl{sup -} by weight of cement). Carbonation was carried out on a powdered sample in flowing 5% CO{sub 2} gas at 65% relative humidity to accelerate the process. At an intermediate carbonation step, a part of the sample was washed and dried up to 10 cycles to simulate a dynamic leaching attack. The two processes were followed by means of X-ray diffraction (XRD), pH and Cl{sup -} analyses in the simulated pore solution.

  9. Calcium-induced patterns of calcium-oxalate crystals in isolated leaflets of Gleditsia triacanthos L. and Albizia julibrissin Durazz.

    PubMed

    Borchert, R

    1985-08-01

    For experimental induction of crystal cells (=crystal idioblasts) containing calcium-oxalate crystals, the lower epidermis was peeled from seedling leaflets of Gleditsia triacanthos L., exposing the crystal-free mesophyll and minor veins to the experimental solutions on which leaflets were floated for up to 10 d under continous light. On 0.3-2.0 mM Ca-acetate, increasing numbers of crystals, appearing 96 h after peeling, were induced. The pattern of crystal distribution changed with Ca(2+)-concentration ([Ca(2+)]): at low [Ca(2+)], crystals formed only in the non-green bundlesheath cells surrounding the veins, believed to have a relatively low Ca(2+)-extrusion capacity; at higher [Ca(2+)], crystals developed in up to 90% of the mesophyll cells, and at supraoptimal [Ca(2+)], large extracellular crystals formed on the tissue surface. By sequential treatments with solutions of different [Ca(2+)], the following three phases were identified in the induction of crystal cells: (1) during the initial 24-h period (adaptive aging), Ca(2+) is not required and crystal induction is not possible; (2) during the following 48 h (induction period), exposure to 1-2 mM Ca-acetate induces the differentiation of mesophyll cells into crystal cells; (3) crystal growth begins 72 h after the start of induction. In intact leaflets of Albizia julibrissin Durazz., calcium-oxalate crystals are found exclusively in the bundle-sheath cells of the veins, but crystals were induced in the mesophyll of peeled leaflets floating on 1 mM Ca-acetate. Exposure to inductive [Ca(2+)] will thus trigger the differentiation of mature leaf cells into crystal cells; the spatial distribution of crystals is determined by the external [Ca(2+)] and by the structural and functional properties of the cells in the tissue. PMID:24241134

  10. CALCULATING THE PH OF CALCIUM CARBONATE SATURATION

    EPA Science Inventory

    Two new expressions for the pH of saturation (pH subs) were derived. One is a simplified equation developed from an aqueous carbonate equilibrium system in which correction for ionic strength was considered. The other is a more accurate quadratic formula that involves computerize...

  11. Bacterial Calcium Carbonate Precipitation in Cave Environments: A Function of Calcium Homeostasis

    Microsoft Academic Search

    Eric D. Banks; Nicholas M. Taylor; Jason Gulley; Brad R. Lubbers; Juan G. Giarrizzo; Heather A. Bullen; Tori M. Hoehler; Hazel A. Barton

    2010-01-01

    To determine if microbial species play an active role in the development of calcium carbonate (CaCO3) deposits (speleothems) in cave environments, we isolated 51 culturable bacteria from a coralloid speleothem and tested their ability to dissolve and precipitate CaCO3. The majority of these isolates could precipitate CaCO3 minerals; scanning electron microscopy and X-ray diffractrometry demonstrated that aragonite, calcite and vaterite

  12. Influence of surface modifiers on the structure of precipitated calcium carbonate

    Microsoft Academic Search

    Rajeev Agnihotri; Suhas K. Mahuli; Shriniwas S. Chauk; Liang-Shih Fan

    1999-01-01

    A calcium carbonate (CaCOâ) sorbent synthesized in the presence of surface modifiers has recently been developed in this laboratory for the purpose of enhancing the reactivity toward SOâ at high temperatures (800--1150 C). The calcium carbonate particles are produced by precipitation from an aqueous suspension of calcium hydroxide by bubbling pure COâ. The operating parameters such as suspension concentration, gas

  13. Mcanismes de prcipitation de carbonate de calcium dans les biofilms photosynthtiques

    E-print Network

    Paris-Sud XI, Université de

    Mécanismes de précipitation de carbonate de calcium dans les biofilms photosynthétiques Pascale carbonate de calcium dans les systèmes benthiques est souvent associée aux biofilms photosynthétiques, et, les stromatolithes et les microbialithes. Cette biocalcification modifie les flux de CO2, de calcium

  14. Calcium oxalate crystals in Aster squamatus and Bellis perennis (Asteraceae: Astereae)

    Microsoft Academic Search

    Ciler Meric

    2009-01-01

    Calcium oxalate crystals in the tissues and organs of Aster squamatus and Bellis perennis (Asteraceae: Astereae) were investigated and their morphology and distribution were determined with a light microscope. Crystals in various sizes in the stem pith cells of A. squamatus were observed as styloids and bipyramids. No crystals were found in the epidermis and cortex cells of the stem.

  15. Determining kinetics of calcium carbonate precipitation by inline technique

    Microsoft Academic Search

    W. N. Al Nasser; A. Shaikh; C. Morriss; M. J. Hounslow; A. D. Salman

    2008-01-01

    Calcium carbonate, CaCO3, is one of the most common scale components found in oilfield production wells and surface facilities. The prediction of kinetics of scale deposit depends on the understanding of the CaCO3 precipitation from solution. The formation of CaCO3 is also of practical importance in a number of areas such as in paper coatings or as fillers for rubber

  16. Extraction of radiostrontium coprecipitated with calcium carbonate in soil

    Microsoft Academic Search

    Spalding

    1985-01-01

    The fraction of soil ZSr coprecipitated with calcium carbonate (CaCO3) was determined by extraction into 0.1M hydrochloric acid (HCl)-0.5M potassium chloride (KCl) after an initial extraction with either 1M ammonium acetate (NH4OAc) or 1M KCl to remove soluble salts and exchangeable cations. This procedure was tested on soil samples supplemented with 85 g CaCO3\\/kg containing coprecipitated YVSr. A significant amount

  17. Calcium carbonate scale control, effect of material and inhibitors.

    PubMed

    Macadam, J; Parsons, S A

    2004-01-01

    This paper focuses on developing a reproducible method for reducing calcium carbonate scale formation on heated surfaces where scaling can cause serious problems. It is known that calcium carbonate precipitation is sensitive to impurity ions, such as iron and zinc, even at trace concentration levels. In this paper two sets of experiments are reported. The first experiments were undertaken to investigate the effect of zinc, copper and iron dosing on CaCO3 nucleation and precipitation. Results from the experiments showed that the most effective inhibitor of CaCO3 precipitation was zinc and the effect was linked to dose levels and temperature. Copper and iron had little effect on precipitation in the dose range investigated. The second trial was undertaken to translate the precipitation data to scale formation. These tests were undertaken at 70 degrees C. 5 mg x L(-1) zinc dose reduced the scale formation by 35%. The effect of iron on calcium carbonate scaling rate was not significant. The physical nature of the material on which the scale is formed also influences the scaling. The scaling experiment was also used to investigate the effect of different surface material (stainless steel, copper and aluminium) on CaCO3 scale formation. Copper surface scaled the most. PMID:14982176

  18. 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. PMID:9469496

  19. Arthritis associated with calcium oxalate crystals in an anephric patient treated with peritoneal dialysis

    SciTech Connect

    Rosenthal, A.; Ryan, L.M.; McCarty, D.J.

    1988-09-02

    The authors report a case of calcium oxalate arthropathy in a woman undergoing intermittent peritoneal dialysis who was not receiving pharmacologic doses of ascorbic acid. She developed acute arthritis, with calcium oxalate crystals in Heberden's and Bouchard's nodes, a phenomenon previously described in gout. Intermittent peritoneal dialysis may be less efficient than hemodialysis in clearing oxalate, and physicians should now consider calcium oxalate-associated arthritis in patients undergoing peritoneal dialysis who are not receiving large doses of ascorbic acid.

  20. Calcium carbonate budget in the Atlantic Ocean based on water column inorganic carbon chemistry

    Microsoft Academic Search

    S.-N. Chung; K. Lee; R. A. Feely; C. L. Sabine; F. J. Millero; R. Wanninkhof; J. L. Bullister; R. M. Key; T.-H. Peng

    2003-01-01

    Recent independent lines of evidence suggest that the dissolution of calcium carbonate (CaCO3) particles is substantial in the upper ocean above the calcite 100 saturation horizon. This shallow-water dissolution of carbonate particles is in contrast with the current paradigm of the conservative nature of pelagic CaCO3 at shallow water depths. Here we use more than 20,000 sets of carbon measurements

  1. Calcium carbonate budget in the Atlantic Ocean based on water column inorganic carbon chemistry

    Microsoft Academic Search

    S.-N. Chung; K. Lee; R. A. Feely; C. L. Sabine; F. J. Millero; R. Wanninkhof; J. L. Bullister; R. M. Key; T.-H. Peng

    2003-01-01

    Recent independent lines of evidence suggest that the dissolution of calcium carbonate (CaCO3) particles is substantial in the upper ocean above the calcite 100% saturation horizon. This shallow-water dissolution of carbonate particles is in contrast with the current paradigm of the conservative nature of pelagic CaCO3 at shallow water depths. Here we use more than 20,000 sets of carbon measurements

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  3. ISOLATED MEDICAGO TRUNCATULA MUTANTS WITH INCREASED CALCIUM OXALATE CRYSTAL ACCUMULATION HAVE DECREASED ASCORBIC ACID LEVELS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mechanisms controlling oxalate biosynthesis and calcium oxalate formation in plants remains largely unknown. As an initial step toward gaining insight into these regulatory mechanisms we initiated a mutant screen to identify plants that over-accumulate crystals of calcium oxalate. Four new mut...

  4. Nonstarter Lactic Acid Bacteria and Aging Temperature Affect Calcium Lactate Crystallization in Cheddar Cheese

    Microsoft Academic Search

    Y.-E. Chou; C. G. Edwards; L. O. Luedecke; M. P. Bates; S. Clark

    2003-01-01

    The occurrence of unappetizing calcium lactate crys- tals in Cheddar cheese is a challenge and expense to manufacturers, and this research was designed to un- derstand their origin. It was hypothesized that non- starter lactic acid bacteria (NSLAB) affect calcium lac- tate crystallization (CLC) by producing D(?)-lactate. This study was designed to understand the effect of NSLAB growth and aging

  5. ADVANCES IN OUR UNDERSTANDING OF CALCIUM OXALATE CRYSTAL FORMATION AND FUNCTION IN PLANTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate crystal formation in plants appears to play a central role in a variety of important functions, including tissue calcium regulation, protection from herbivory, and metal detoxification. Evidence is mounting to support ascorbic acid as the primary precursor to oxalate biosynthesis. ...

  6. 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

  7. Skeletal development in Acropora cervicornis: I. Patterns of calcium carbonate accretion in the axial corallite

    NASA Astrophysics Data System (ADS)

    Gladfeiter, E. H.

    1982-06-01

    Scanning electron microscopy and serial petrographic thin sections were used to investigate skeletal elongation and mineralization in the perforate coral, Acropora cervicornis. The axial corallite extends by the formation of randomly oriented fusiform crystals which are deposited on its distal edge. Aragonitic needle-like crystals grow in random directions from the surface of these fusiform crystals. Only those needle-like crystals growing toward the calicoblastic epithelium (i.e. crystals whose growth axis is perpendicular to the plane of the calicoblastic cell membrane) continue to elongate. Groups of these growing crystals join to form well-defined fasciculi which make up the primary skeletal elements comprising the septotheca. The resulting skeleton is highly porous with all surfaces covered by the continuous calicoblastic epithelium. This cell layer is separated by thin mesoglea from the flagellated gastrodermis which lines the highly ramified coelenteron. Porosity and permeability of the skeleton decrease with distance from the tip. Density correspondingly increases due to the addition of aragonite to the fasciculi whose boundaries become less distinct as channels fill with calcium carbonate.

  8. Precipitation of calcium carbonate and calcium phosphate under diffusion controlled mixing

    SciTech Connect

    Tsigabu Gebrehiwet; James R. Henriksen; Luanjing Guo; Don T. Fox; Hai Huang; Lee Tu; Yoshiko Fujita; Robert W. Smith; George Redden

    2014-07-01

    Multi-component mineral precipitation in porous, subsurface environments is challenging to simulate or engineer when in situ reactant mixing is controlled by diffusion. In contrast to well-mixed systems, the conditions that favor mineral precipitation in porous media are distributed along chemical gradients, which evolve spatially due to concurrent mineral precipitation and modification of solute transport in the media. The resulting physical and chemical characteristics of a mixing/precipitation zone are a consequence of coupling between transport and chemical processes, and the distinctive properties of individual chemical systems. We examined the spatial distribution of precipitates formed in “double diffusion” columns for two chemical systems, calcium carbonate and calcium phosphate. Polyacrylamide hydrogel was used as a low permeability, high porosity medium to maximize diffusive mixing and minimize pressure- and density-driven flow between reactant solutions. In the calcium phosphate system, multiple, visually dense and narrow bands of precipitates were observed that were reminiscent of previously reported Liesegang patterns. In the calcium carbonate system, wider precipitation zones characterized by more sparse distributions of precipitates and a more open channel structure were observed. In both cases, formation of precipitates inhibited, but did not necessarily eliminate, continued transport and mixing of the reactants. A reactive transport model with fully implicit coupling between diffusion, chemical speciation and precipitation kinetics, but where explicit details of nucleation processes were neglected, was able to qualitatively simulate properties of the precipitation zones. The results help to illustrate how changes in the physical properties of a precipitation zone depend on coupling between diffusion-controlled reactant mixing and chemistry-specific details of precipitation kinetics.

  9. Plants defective in calcium oxalate crystal formation have more bioavailable calcium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bioavailable calcium affects bone formation and calcification. Here we investigate how a single gene mutation altering calcium partitioning in the forage crop Medicago truncatula affects calcium bioavailability. Previously, the cod5 Medicago mutant was identified which contains wild-type amounts o...

  10. Calcium carbonate-calcium phosphate mixed cement compositions for bone reconstruction.

    PubMed

    Combes, C; Bareille, R; Rey, C

    2006-11-01

    The feasibility of making calcium carbonate-calcium phosphate (CaCO(3)-CaP) mixed cements, comprising at least 40% (w/w) CaCO(3) in the dry powder ingredients, has been demonstrated. Several original cement compositions were obtained by mixing metastable crystalline CaCO(3) phases with metastable amorphous or crystalline CaP powders in aqueous medium. The cements set within at most 1 h at 37 degrees C in atmosphere saturated with water. The hardened cement is microporous and exhibits weak compressive strength. The setting reaction appeared to be essentially related to the formation of a highly carbonated nanocrystalline apatite phase by reaction of the metastable CaP phase with part or almost all of the metastable CaCO(3) phase. The recrystallization of metastable CaP varieties led to a final cement consisting of a highly carbonated poorly crystalline apatite analogous to bone mineral associated with various amounts of vaterite and/or aragonite. The presence of controlled amounts of CaCO(3) with a higher solubility than that of the apatite formed in the well-developed CaP cements might be of interest to increase resorption rates in biomedical cement and favors its replacement by bone tissue. Cytotoxicity testing revealed excellent cytocompatibility of CaCO(3)-CaP mixed cement compositions. PMID:16817210

  11. Influence of polyvinylpyrrolidone on the precipitation of calcium carbonate and on the transformation of vaterite to calcite

    Microsoft Academic Search

    Hao Wei; Qiang Shen; Ying Zhao; Du-Jin Wang; Duan-Fu Xu

    2003-01-01

    The precipitation process of calcium carbonate (CaCO3) in the absence and presence of poly (N-vinyl-2-pyrrolidone) (PVP) was investigated using scanning electron microscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy methods at room temperature. The results indicate that PVP does not affect the polymorphy, but has influence on their morphology and size of CaCO3 crystals. With the addition of PVP,

  12. Rhesus monkeys (Macaca mulatta) as a model for calcium pyrophosphate dihydrate crystal deposition disease.

    PubMed

    Renlund, R C; Pritzker, K P; Cheng, P T; Kessler, M J

    1986-01-01

    Calcium pyrophosphate dihydrate crystal deposition disease (CPDD) was recognized in 4 of 30 free-ranging rhesus macaques. By means of tissue radiography, focal radiodensities were noted in lumbar intervertebral discs, menisci, and articular cartilage. Crystal deposits were identified as calcium pyrophosphate dihydrate (Ca2P2O7 X 2H2O) by means of X-ray diffraction. The pathogenesis of calcium pyrophosphate dihydrate arthropathy in man remains elusive. However, with the recognition of this arthritis in a well defined population of aged nonhuman primates, a model now exists to facilitate the study of this disease. PMID:3009819

  13. Evaluation of cellular influences caused by calcium carbonate nanoparticles.

    PubMed

    Horie, Masanori; Nishio, Keiko; Kato, Haruhisa; Endoh, Shigehisa; Fujita, Katsuhide; Nakamura, Ayako; Kinugasa, Shinichi; Hagihara, Yoshihisa; Yoshida, Yasukazu; Iwahashi, Hitoshi

    2014-03-01

    The cellular effects of calcium carbonate (CaCO?) nanoparticles were evaluated. Three kinds of CaCO? nanoparticles were employed in our examinations. One of the types of CaCO? nanoparticles was highly soluble. And solubility of another type of CaCO? nanoparticle was lower. A stable CaCO? nanoparticle medium dispersion was prepared and applied to human lung carcinoma A549 cells and human keratinocyte HaCaT cells. Then, mitochondrial activity, cell membrane damage, colony formation ability, DNA injury, induction of oxidative stress, and apoptosis were evaluated. Although the influences of CaCO? nanoparticles on mitochondrial activity and cell membrane damage were small, "soluble" CaCO? nanoparticles exerted some cellular influences. Soluble CaCO? nanoparticles also induced a cell morphological change. Colony formation was inhibited by CaCO? nanoparticle exposure. In particular, soluble CaCO? nanoparticles completely inhibited colony formation. The influence on intracellular the reactive oxygen species (ROS) level was small. Soluble CaCO? nanoparticles caused an increase in C/EBP-homologous protein (CHOP) expression and the activation of caspase-3. Moreover, CaCO? exposure increased intracellular the Ca²? level and activated calpain. These results suggest that cellular the influences of CaCO? nanoparticles are mainly caused by intracellular calcium release and subsequently disrupt the effect of calcium signaling. In conclusion, there is possibility that soluble CaCO? nanoparticles induce cellular influences such as a cell morphological change. Cellular influence of CaCO? nanoparticles is caused by intracellular calcium release. If inhaled CaCO? nanoparticles have the potential to influence cellular events. However, the effect might be not severe because calcium is omnipresent element in cell. PMID:24412303

  14. 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.

  15. 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. PMID:24753014

  16. Calcium carbonate precipitation in cyanobacterial mats from sandy tidal flats of the North Sea.

    PubMed

    Kremer, B; Kazmierczak, J; Stal, L J

    2008-01-01

    Precipitated calcium carbonate was found in annual cyanobacterial mats developing on the beaches of the North Sea barrier island Schiermonnikoog (the Netherlands). A variety of different calcium carbonate morphs were found in the cyanobacterial mucous secretions and identified by light- and scanning electron microscopy and X-ray diffraction. Most of the calcium carbonate seemed to be associated with degrading extracellular polymer. It is conceived that supersaturation of calcium carbonate resulted from the periodic evaporation of the mats and from the release of calcium from the cyanobacterial mucous as a result of its degradation. The analysis of the carbon stable isotopic composition of the calcium carbonate showed only a slight depletion of (13)C, indicating that it did not in major part originated from the decomposition of organic matter. The delta(18)O values of the calcium carbonate confirmed the temperature differences between spring and summer but excluded the possibility that excessive evaporative events controlled precipitation. The precipitation of calcium carbonate could represent a potential factor enhancing the stabilization of intertidal siliciclastic sediments through cementing the sand. The discovery of massive calcium carbonate precipitation in these cyanobacterial mats was unexpected and hitherto unknown. PMID:18380885

  17. Non-aqueous formation of the calcium carbonate polymorph vaterite: astrophysical implications

    E-print Network

    Day, Sarah J; Parker, Julia E; Evans, Aneurin

    2013-01-01

    We study the formation of calcium carbonate, through the solid-gas interaction of amorphous Ca-silicate with gaseous CO2, at elevated pressures, and link this to the possible presence of calcium carbonate in a number of circumstellar and planetary environments. We use in-situ synchrotron X-Ray powder diffraction to obtain detailed structural data pertaining to the formation of the crystalline calcium carbonate phase vaterite and its evolution with temperature. We found that the metastable calcium carbonate phase vaterite was formed alongside calcite, at elevated CO2 pressure, at room temperature and subsequently remained stable over a large range of temperature and pressure. We report the formation of the calcium carbonate mineral vaterite whilst attempting to simulate carbonate dust grain formation in astrophysical environments. This suggests that vaterite could be a mineral component of carbonate dust and also presents a possible method of formation for vaterite and its polymorphs on planetary surfaces.

  18. [Modulation of polysaccharide extracted from Laminaria on phase compositions of urinary crystal calcium oxalate].

    PubMed

    Deng, Sui-Ping; Ouyang, Jian-Ming

    2007-11-01

    The influence of sulfate polysaccharide (SPS) isolated from marine algae Laminaria japonica aresch on the growth of urinary crystal calcium oxalate (CaO(xa)) was investigated by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic absorption spectroscopy. SPS can stabilize thermodynamic metastable calcium oxalate dihydrate (COD) crystals. As the concentration of SPS increases from 0 to 0.60 mg x mL(-1), the mass percentage of COD crystals increases from 0 to 100%, and the relative supersaturation of calcium oxalate increases from 1.0 to 19.6. The ability of SPS to stabilize the existence of COD in aqueous solution and to increase the concentration of soluble calcium ions is favorable to the inhibition of CaO(xa) stone. Indicating that SPS is a potential green drug for prevention and cure of CaO(xa) urinary stones. PMID:18260434

  19. Adhesion of calcium oxalate monohydrate crystals to renal epithelial cells is inhibited by specific anions.

    PubMed

    Lieske, J C; Leonard, R; Toback, F G

    1995-04-01

    Adhesion of urinary crystals to the apical surface of renal tubular cells could be a critical step in the formation of kidney stones. The interaction between renal epithelial cells (BSC-1 line) and the most common crystal in kidney stones, calcium oxalate monohydrate (COM), was studied in a tissue culture model system. COM crystals bound to the cell surface within seconds in a concentration-dependent manner to a far greater extent than did brushite, another calcium-containing crystal found in urine. Adhesion of COM crystals to cells was blocked by the polyanion, heparin. Other glycosaminoglycans including chondroitin sulfate A or B, heparan sulfate, and hyaluronic acid, but not chondroitin sulfate C, prevented binding of COM crystals. Two nonsulfated polyanions, polyglutamic acid and polyaspartic acid, also blocked adherence of COM crystals. Three molecules found in urine, nephrocalcin, uropontin, and citrate, each inhibited binding of COM crystals, whereas Tamm-Horsfall glycoprotein (THP) did not. Prior exposure of crystals but not cells to inhibitory molecules blocked adhesion, suggesting that these agents exert their effect at the crystal surface. Inhibition of crystal binding followed a linear Langmuir adsorption isotherm for each inhibitor identified, suggesting that these molecules bind to a single class of sites on the crystal that are important for adhesion to the cell surface. Inhibition of crystal adhesion by heparin was rapidly overcome by the polycation protamine, suggesting that the glycosaminoglycan regulates cell-crystal interactions in a potentially reversible manner.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7733317

  20. The Effect of Calcium and Magnesium on Carbonate Mineral Precipitation during Reactive Transport in a Model Subsurface Pore Structure

    NASA Astrophysics Data System (ADS)

    Boyd, V.; Werth, C. J.; Valocchi, A. J.; Fouke, B. W.

    2012-12-01

    Carbonate mineral precipitation in the subsurface at the interface of two advecting fluids can result in physical and chemical changes in the pore network. This can affect various applications including carbon sequestration. In this work, we evaluate the precipitation kinetics of carbonates in a microfluidic pore network when carbonate in water is mixed transverse to flow with a synthetic brine containing an equimolar concentration of calcium (Ca, 10 mM) and concentrations of magnesium (Mg) ranging from 2 to 40 mM. Mineral precipitation was monitored using reflected brightfield microscopy and mineral polymorphs were determined using Raman spectroscopy. Although Mg was present, only calcium carbonate (CaCO3) polymorphs were observed. The presence of Mg affected both the rate of precipitation and the prevalence of different CaCO3 morphologies. The rate of precipitation with 40mM Mg was about half of the rate as when no Mg was present. The calcium carbonate polymorph aragonite increased from <5% of the precipitated crystal area to >20% as the Mg concentration increased from 0 mM to 40 mM. Energy dispersive spectroscopy (EDS) results showed Mg2+ incorporated into the crystal lattice of the CaCO3 polymorph calcite at 8 to 14 mole% when Mg concentration in solution was highest. The incorporation of Mg2+ into the crystals was likely responsible for the reduction in precipitation rate at high solution concentrations of Mg. Significant pore blockage occurred along the mixing zone, indicating that carbonate precipitation may be of concern along the CO2 plume margins and affect the efficiency of CO2 injection.

  1. Leaf calcium oxalate crystal structure and its role in defense against a chewing insect in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crystals of calcium oxalate are common in plants and widely distributed among many plant families. These hard and largely insoluble crystals take on many shapes and sizes depending on the tissue and species. In Medicago truncatula, calcium oxalate crystals are abundant in leaves and accumulate in sh...

  2. Spectral features of biogenic calcium carbonates and implications for astrobiology

    NASA Astrophysics Data System (ADS)

    Berg, B. L.; Ronholm, J.; Applin, D. M.; Mann, P.; Izawa, M.; Cloutis, E. A.; Whyte, L. G.

    2014-09-01

    The ability to discriminate biogenic from abiogenic calcium carbonate (CaCO3) would be useful in the search for extant or extinct life, since CaCO3 can be produced by both biotic and abiotic processes on Earth. Bioprecipitated CaCO3 material was produced during the growth of heterotrophic microbial isolates on medium enriched with calcium acetate or calcium citrate. These biologically produced CaCO3, along with natural and synthetic non-biologically produced CaCO3 samples, were analysed by reflectance spectroscopy (0.35-2.5 ?m), Raman spectroscopy (532 and 785 nm), and laser-induced fluorescence spectroscopy (365 and 405 nm excitation). Optimal instruments for the discrimination of biogenic from abiogenic CaCO3 were determined to be reflectance spectroscopy, and laser-induced fluorescence spectroscopy. Multiple absorption features in the visible light region occurred in reflectance spectra for most biogenic CaCO3 samples, which are likely due to organic pigments. Multiple fluorescence peaks occurred in emission spectra (405 nm excitation) of biogenic CaCO3 samples, which also are best attributed to the presence of organic compounds; however, further analyses must be performed in order to better determine the cause of these features to establish criteria for confirming the origin of a given CaCO3 sample. Raman spectroscopy was not useful for discrimination since any potential Raman peaks in spectra of biogenic carbonates collected by both the 532 and 785 nm lasers were overwhelmed by fluorescence. However, this also suggests that biogenic carbonates may be identified by the presence of this organic-associated fluorescence. No reliable spectroscopic differences in terms of parameters such as positions or widths of carbonate-associated absorption bands were found between the biogenic and abiogenic carbonate samples. These results indicate that the presence or absence of organic matter intimately associated with carbonate minerals is the only potentially useful spectral discriminator for the techniques that were examined, and that multiple spectroscopic techniques are capable of detecting the presence of associated organic materials. However, the presence or absence of intimately associated organic matter is not, in itself, an indicator of biogenicity.

  3. CALCIUM OXALATE CRYSTALS IN LEAVES OF GLYCINE SPECIES AND RELATED TAXA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate (CaOx) crystals occur in about three-fourths of all the flowering plants. The location and structure of the crystals have been used in some systematic studies. The Genus Glycine includes the cultivated soybean, the wild annual soybean, and about 22 wild perennial species. Our obje...

  4. Calcium Carbonate Produced by Coccolithophorid Algae in Long Term, Carbon Dioxide Sequestration

    SciTech Connect

    V.J. Fabry

    2007-06-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO2 through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids - single-celled, marine algae that are the major global producers of calcium carbonate - to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  5. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry

    2004-10-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds or bioreactors to abate CO{sub 2} emissions from power plants.

  6. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry

    2001-07-01

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids single-celled, marine algae that are the major global producers of calcium carbonate to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  7. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2001-12-15

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  8. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2001-09-10

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  9. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-12-15

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  10. CALCIUM CARBONATE PRODUCTION BY COCCOLITHAPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V. J.Fabry

    2004-01-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  11. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V. J. Fabry

    2003-10-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds or bioreactors to abate CO{sub 2} emissions from power plants.

  12. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2003-07-15

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  13. Calcium Carbonate Production by Coccolithophorid Algae in Long Term, Carbon Dioxide Sequestration

    SciTech Connect

    V.J. Fabry

    2005-04-29

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  14. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-09-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  15. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-07-09

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  16. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry

    2004-04-26

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids single-celled, marine algae that are the major global producers of calcium carbonate to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  17. Calcium Carbonate Production by Coccolithophorid Alge in Long Term Carbon Dioxide Sequestration

    SciTech Connect

    V. J. Fabry

    2006-09-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  18. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2003-04-15

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  19. Calcium Carbonate Production by Coccolithophorid Algae in Long Term, Carbon Dioxide Sequestration

    SciTech Connect

    V. J. Fabry

    2006-06-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  20. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V. J. Fabry

    2005-01-24

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids ? single-celled, marine algae that are the major global producers of calcium carbonate ? to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  1. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-04-05

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  2. Kinetic fractionation of carbon-13 during calcium carbonate precipitation

    Microsoft Academic Search

    Jeffrey V. Turner

    1982-01-01

    Kinetic isotope fractionation of 13 C during precipitation of CaCO 3 under open system conditions has been investigated. The isotope enrichment factor HCO 3 - - CaCO 3 varies between -0.35 ± 0.23 and -3.37 ± 0.36%. at 25°C depending on the rate of precipitation and mineralogy, the enrichment of 13 C in the solid carbonate phase decreasing with increasing

  3. A mineralogical characterization of biogenic calcium carbonates precipitated by heterotrophic bacteria isolated from cryophilic polar regions.

    PubMed

    Ronholm, J; Schumann, D; Sapers, H M; Izawa, M; Applin, D; Berg, B; Mann, P; Vali, H; Flemming, R L; Cloutis, E A; Whyte, L G

    2014-11-01

    Precipitation of calcium carbonate (CaCO3(s) ) can be driven by microbial activity. Here, a systematic approach is used to identify the morphological and mineralogical characteristics of CaCO3(s) precipitated during the heterotrophic growth of micro-organisms isolated from polar environments. Focus was placed on establishing mineralogical features that are common in bioliths formed during heterotrophic activity, while in parallel identifying features that are specific to bioliths precipitated by certain microbial phylotypes. Twenty microbial isolates that precipitated macroscopic CaCO3(s) when grown on B4 media supplemented with calcium acetate or calcium citrate were identified. A multimethod approach, including scanning electron microscopy, high-resolution transmission electron microscopy, and micro-X-ray diffraction (?-XRD), was used to characterize CaCO3(s) precipitates. Scanning and transmission electron microscopy showed that complete CaCO3(s) crystal encrustation of Arthrobacter sp. cells was common, while encrustation of Rhodococcus sp. cells did not occur. Several euhedral and anhedral mineral formations including disphenoid-like epitaxial plates, rhomboid-like aggregates with epitaxial rhombs, and spherulite aggregates were observed. While phylotype could not be linked to specific mineral formations, isolates tended to precipitate either euhedral or anhedral minerals, but not both. Three anhydrous CaCO3(s) polymorphs (calcite, aragonite, and vaterite) were identified by ?-XRD, and calcite and aragonite were also identified based on TEM lattice-fringe d value measurements. The presence of certain polymorphs was not indicative of biogenic origin, although several mineralogical features such as crystal-encrusted bacterial cells, or casts of bacterial cells embedded in mesocrystals are an indication of biogenic origin. In addition, some features such as the formation of vaterite and bacterial entombment appear to be linked to certain phylotypes. Identifying phylotypes consistent with certain mineralogical features is the first step toward discovering a link between these crystal features and the precise underlying molecular biology of the organism precipitating them. PMID:25256888

  4. A multicenter study on the effects of lanthanum carbonate (Fosrenol™) and calcium carbonate on renal bone disease in dialysis patients

    Microsoft Academic Search

    Patrick C. D'Haese; Goce B. Spasovski; Aleksander Sikole; Alastair Hutchison; Tony J. Freemont; Sylvie Sulkova; Charles Swanepoel; Svetlana Pejanovic; Llubica Djukanovic; Alessandro Balducci; Giorgio Coen; Waldysaw Sulowicz; Anibal Ferreira; Armando Torres; Slobodan Curic; Milan Popovic; Nada Dimkovic; Marc E. De Broe

    2003-01-01

    A multicenter study on the affects of lanthanum carbonate (Fosrenol™) and calcium carbonate on renal bone disease in dialysis patients.BackgroundLanthanum carbonate (LC) (Fosrenol™) is a novel new treatment for hyperphosphatemia. In this phase III, open-label study, we compared the effects of LC and calcium carbonate (CC) on the evolution of renal osteodystrophy (ROD) in dialysis patients.MethodsNinety-eight patients were randomized to

  5. Carbon nanopipettes characterize calcium release pathways in breast cancer cells

    NASA Astrophysics Data System (ADS)

    Schrlau, Michael G.; Brailoiu, Eugen; Patel, Sandip; Gogotsi, Yury; Dun, Nae J.; Bau, Haim H.

    2008-08-01

    Carbon-based nanoprobes are attractive for minimally invasive cell interrogation but their application in cell physiology has thus far been limited. We have developed carbon nanopipettes (CNPs) with nanoscopic tips and used them to inject calcium-mobilizing messengers into cells without compromising cell viability. We identify pathways sensitive to cyclic adenosine diphosphate ribose (cADPr) and nicotinic acid adenine dinucleotide phosphate (NAADP) in breast carcinoma cells. Our findings demonstrate the superior utility of CNPs for intracellular delivery of impermeant molecules and, more generally, for cell physiology studies. The CNPs do not appear to cause any lasting damage to cells. Their advantages over commonly used glass pipettes include smaller size, breakage and clogging resistance, and potential for multifunctionality such as in concurrent injection and electrical measurements.

  6. Intracrystalline Proteins and the Hidden Ultrastructure of Calcium Oxalate Urinary Crystals: Implications for Kidney Stone Formation

    Microsoft Academic Search

    Rosemary Lyons Ryall; David E. Fleming; Ian R. Doyle; Natalie A. Evans; Caroline J. Dean; Villis R. Marshall

    2001-01-01

    Theexternal appearance of urinary calcium oxalate (CaOx) crystals suggests that they are solid, homogeneous structures, despite their known association with proteins. Our aim was to determine whether proteins comprising the organic matrix of CaOx crystals are superficial or intracrystalline in order to clarify the role of urinary proteins in the formation of kidney stones. CaOx crystals were precipitated from centrifuged

  7. Tamm-Horsfall glycoprotein-inhibitor or promoter of calcium oxalate monohydrate crystallization processes?

    Microsoft Academic Search

    B. Hess; Gerhardt A; Brit J Nutr; Paul O. Schwille

    1992-01-01

    The processes of calcium oxalate monohydrate (COM) crystal nucleation, growth and aggregation (agglomeration) generally have been studied using a wide variety of assay systems\\/conditions. This paper reviews the apparently conflicting data on the effects of Tamm-Horsfall glycoprotein (THP) on COM crystallization processes in vitro, with the main emphasis on crystal aggregation. According to its well-known physico-chemical properties. THP has a

  8. Continuous precipitation of calcium carbonate using sonochemical reactor.

    PubMed

    Shirsath, S R; Sonawane, S H; Saini, D R; Pandit, A B

    2015-05-01

    The continuous production of calcium carbonate (CaCO3) by precipitation method at room temperature was carried out in a stirred reactor under ultrasonic environment and was compared with the conventional stirring method. The effect of various operating parameters such as Ca(OH)2 slurry concentration, CO2 flow rate and Ca(OH)2 slurry flow rate on the particle size of CaCO3 was investigated. The calcium carbonate particles were characterized by Fourier transform infrared (FTIR), wide angle X-ray diffraction (WXRD) and particle size. The morphology was studied by using scanning electron microscopic (SEM) images. The particle size obtained in the presence of ultrasonic environment was found to be smaller as compared to conventional stirring method. The particle size is found to be reduced with an increase in the concentrations of Ca(OH)2 and increased with increasing CO2 flow rate for both the methods. The slurry flow rate had a major effect on the particle size and the particle size decreased with increased slurry flow rate. Only calcite phase of CaCO3 was predominantly present as confirmed by the characterization techniques for both the preparation methods. In most of the cases rhombohedral calcite particles were observed. PMID:25534035

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

    SciTech Connect

    Mesbah, Adel [Commissariat a l'Energie Atomique et aux Energies Alternatives, CEA DEN/DTCD/SPDE, F-30207 Bagnols sur Ceze (France); Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); Cau-dit-Coumes, Celine, E-mail: celine.cau-dit-coumes@cea.fr [Commissariat a l'Energie Atomique et aux Energies Alternatives, CEA DEN/DTCD/SPDE, F-30207 Bagnols sur Ceze (France); Renaudin, Guillaume [Clermont Universite, ENSCCF, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, F-63177 Aubiere (France); Frizon, Fabien [Commissariat a l'Energie Atomique et aux Energies Alternatives, CEA DEN/DTCD/SPDE, F-30207 Bagnols sur Ceze (France); Leroux, Fabrice [Clermont Universite, Universite Blaise Pascal, Laboratoire des Materiaux Inorganiques, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6002, F-63177 Aubiere (France)

    2012-08-15

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

  10. Effect of calcium carbonate saturation of seawater on coral calcification

    USGS Publications Warehouse

    Gattuso, J.-P.; Frankignoulle, M.; Bourge, I.; Romaine, S.; Buddemeier, R.W.

    1998-01-01

    The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata in synthetic seawater using the alkalinity anomaly technique. Changes in aragonite saturation from 98% to 585% were obtained by manipulating the calcium concentration. The results show a nonlinear increase in calcification rate as a function of aragonite saturation level. Calcification increases nearly 3-fold when aragonite saturation increases from 98% to 390%, i.e., close to the typical present saturation state of tropical seawater. There is no further increase of calcification at saturation values above this threshold. Preliminary data suggest that another coral species, Acropora sp., displays a similar behaviour. These experimental results suggest: (l) that the rate of calcification does not change significantly within the range of saturation levels corresponding to the last glacial-interglacial cycle, and (2) that it may decrease significantly in the future as a result of the decrease in the saturation level due to anthropogenic release of CO2 into the atmosphere. Experimental studies that control environmental conditions and seawater composition provide unique opportunities to unravel the response of corals to global environmental changes.

  11. Two year comparison of sevelamer and calcium carbonate effects on cardiovascular calcification and bone density

    Microsoft Academic Search

    Hans-Gernot Asmus; Johan Braun; Rolfdieter Krause; Reinhard Brunkhorst; Herwig Holzer; Walter Schulz; Hans-Hellmut Neumayer; Paolo Raggi; Jurgen Bommer

    2005-01-01

    Background. Calcium-based phosphate binders may induce tissue calcification, and little is known about their effects on bone density. We compared the effects of a calcium with a non-calcium phosphate binder on both arterial calcification and bone density measured by computed tomography. Methods. Seventy-two adult haemodialysis patients were randomized to treatment with calcium carbonate (CC) or sevelamer (SEV) for 2 years.

  12. [Crystallization of calcium phosphate in the presence of magnesium].

    PubMed

    Boistelle, R; Lopez-Valero, I; Abbona, F

    1993-01-01

    Formation and evolution of calcium phosphates are investigated, at 37 degrees C, in urine and aqueous solutions whose concentrations in calcium and magnesium are close to those of urine. Although the solutions are supersaturated with respect to all calcium phosphates, only an amorphous phase (ACP) and brushite (B) precipitate at time zero. Later on, ACP transforms either into whitlockite (W) or into apatite (HAP) depending on the solution composition. Phase transformations are discussed in terms of supersaturation, parameter which includes concentrations and pH. It is also shown that magnesium is a powerful inhibitor of the evolution towards HAP. PMID:8145884

  13. A new method for the study of trace element partitioning between calcium carbonate and aqueous solution: A test case for Sr and Ba incorporation into calcite

    Microsoft Academic Search

    YASUTAKA TERAKADO; MAMI TANIGUCHI

    2006-01-01

    A new experimental method (evaporation method) for calcium carbonate precipitation in aqueous solution was at- tempted in order to develop a convenient and controllable experimental technique for obtaining precise trace element partition coefficients. Calcite crystals were formed by evaporation of H2O from the aqueous mother solution using a dehumidifier, and the consumed Ca ions were supplied from a refill solution

  14. Image-based Modeling of Biofilm-induced Calcium Carbonate Precipitation

    NASA Astrophysics Data System (ADS)

    Connolly, J. M.; Rothman, A.; Jackson, B.; Klapper, I.; Cunningham, A. B.; Gerlach, R.

    2013-12-01

    Pore scale biological processes in the subsurface environment are important to understand in relation to many engineering applications including environmental contaminant remediation, geologic carbon sequestration, and petroleum production. Specifically, biofilm induced calcium carbonate precipitation has been identified as an attractive option to reduce permeability in a lasting way in the subsurface. This technology may be able to replace typical cement-based grouting in some circumstances; however, pore-scale processes must be better understood for it to be applied in a controlled manor. The work presented will focus on efforts to observe biofilm growth and ureolysis-induced mineral precipitation in micro-fabricated flow cells combined with finite element modelling as a tool to predict local chemical gradients of interest (see figure). We have been able to observe this phenomenon over time using a novel model organism that is able to hydrolyse urea and express a fluorescent protein allowing for non-invasive observation over time with confocal microscopy. The results of this study show the likely existence of a wide range of local saturation indices even in a small (1 cm length scale) experimental system. Interestingly, the locations of high predicted index do not correspond to the locations of higher precipitation density, highlighting the need for further understanding. Figure 1 - A micro-fabricated flow cell containing biofilm-induced calcium carbonate precipitation. (A) Experimental results: Active biofilm is in green and dark circles are calcium carbonate crystals. Note the channeling behavior in the top of the image, leaving a large hydraulically inactive area in the biofilm mass. (B) Finite element model: The prediction of relative saturation of calcium carbonate (as calcite). Fluid enters the system at a low saturation state (blue) but areas of high supersaturation (red) are predicted within the hydraulically inactive area in the biofilm. If only effluent saturation was measured, precipitation may not even be predicted but we see local, pore-scale behavior dictating system behavior in this case. The flow cell is 1 cm in length and the porous media elements are 100 ?m.

  15. Magnesium and Strontium Incorporation into Calcium Carbonate Polymorphs and ACC - Experimental Study

    NASA Astrophysics Data System (ADS)

    Niedermayr, A.; Dietzel, M.; Köhler, S. J.; Petautschnig, S.

    2010-05-01

    Incorporation of magnesium and strontium into aragonite and calcite is well known and has been extensively used for temperature reconstruction. Moreover, knowledge on element incorporation behaviour provides fundamental insight into calcium carbonate growth mechanisms. Element and isotope distributions are also used for monitoring aspects to evaluate ongoing sinter formation and inhibition effects in man made environments. However, the precipitation rate impact on magnesium and strontium incorporation in aragonite as well as the effect of magnesium on strontium incorporation in calcite is still a matter of debate, and little is known about the incorporation behaviour of magnesium and strontium in amorphous calcium carbonate (ACC) and vaterite. In this study, magnesium and strontium incorporation into the three calcium carbonate polymorphs and ACC are experimentally investigated at low temperature. Spontaneous calcium carbonate precipitation experiments without seeds were carried out using a CO2-diffusion technique (TANG et al., 2008) and batch mixing. Experiments are conducted (i) at various Mg/Ca ratios (up to 10), and/or (ii) in presence of polyaspartic acid at temperatures from 5° to 50° C and various CO2-uptake rates. In the mixing experiments a metal chloride solution is rapidly mixed with a sodium (hydrogen-) carbonate solution. Calcite is preferentially formed at lower temperatures, at lower supersaturation degrees (?) and low Mg/Ca ratios, while aragonite is preferentially formed at high Mg/Ca ratios and/or at elevated temperatures. Vaterite is formed at relatively high ? values and in presence of polyaspartic acid. ACC is obtained at the highest supersaturation in mixing experiments and its formation is stimulated by magnesium. If magnesium is present, calcite crystals have a steep rhombic or pseudo dodecahedronal shape with a rougher surface and acute sides are rounded. This affects strontium incorporation. Generally, strontium incorporation increases with increasing precipitation rate for calcite and vaterite, while the inverse is observed for aragonite. Incorporation of magnesium is similar for calcite, vaterite and ACC, and smallest for aragonite. Preliminary results indicate that strontium incorporation in ACC is correlated with magnesium incorporation. Respective processes and proposed models are discussed. Reference: Tang J., Köhler S.J. and Dietzel M. (2008) Sr2+/Ca2+ and 44Ca/40Ca fractionation during inorganic calcite formation: I. Sr incorporation, Geochimica et Cosmochimica Acta, 72, 3718-3732.

  16. Calcium

    MedlinePLUS

    ... following: Milk, yogurt, and cheese are the main food sources of calcium for the majority of people in ... on Calcium Minerals, MedlinePlus® For more information on food sources of calcium: U.S. Department of Agriculture's (USDA) National ...

  17. Introduction The formation of solid calcium carbonate (CaCO3) is

    E-print Network

    Hell, Stefan W.

    Introduction The formation of solid calcium carbonate (CaCO3) is an important process in biological the active components, and methyl octadeca- noate (MOD) the inactive matrix. Surface pressure-area isotherms calcium carbonate (CaCO3) with two-component monolayers on sub- phases containing aqueous CaCO3

  18. 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. PMID:17765416

  19. Temperature-Dependent Heterogeneous Efflorescence of Mixed Ammonium Sulfate/Calcium Carbonate Particles

    E-print Network

    Temperature-Dependent Heterogeneous Efflorescence of Mixed Ammonium Sulfate/Calcium Carbonate to exist in two metastable liquid states: (a) supersaturated with respect to both ammonium sulfate and calcium carbonate and (b) supersaturated with respect to ammonium sulfate and saturated with respect

  20. 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

  1. THE INFLUENCE OF CALCIUM CARBONATE GRAIN COATINGS ON CONTAMINANT REACTIVITY IN VADOSE ZONE SEDIMENTS

    EPA Science Inventory

    Fundamental research is proposed to investigate the role of calcium carbonate grain coatings on the vadose zone chemical reactivity of key Hanford contaminants (i.e., 60Co2+, 90Sr2+, CrO42-, and 99TcO4-). Calcium carbonate is widely distributed through the Hanford vadose zone as...

  2. Prediction of calcium carbonate scaling from water in solar energy systems

    Microsoft Academic Search

    I. Singh; C. F. Cheng; P. S. Chopra

    1979-01-01

    Water samples collected from subsystems at five Solar Heating and Cooling (SHAC) demonstration sites were assessed for chemical scaling deposition. Collector surfaces are the most likely area for scale formation, and the deposits are most likely to be calcium carbonate. Solar designers and operators can now employ a two-step approach to determine whether water-treatment is required to prevent calcium carbonate

  3. Evidence for a fragmentation mechanism during the formation of calcium carbonate organo-nano-particles

    Microsoft Academic Search

    Ian D. Cunningham; Jean-Philippe Courtois; Timothy N. Danks; David M. Heyes; David J. Moreton; Spencer E. Taylor

    2007-01-01

    13C NMR and Langmuir trough measurements have been used to monitor physico-chemical changes taking place during the carbonation of a calcium hydroxide in hexadecane suspension in the presence of calixarene and stearic acid as stabilizers. The initial reaction, before carbonation, is characterized by neutralization of the outer surface of the suspended calcium hydroxide particles by the surfactant species present. However,

  4. Calcium carbonate inhibition by a phosphonate-terminated poly(maleic-co-sulfonate) polymeric inhibitor

    Microsoft Academic Search

    Chen Wang; Shu-ping Li; Tian-duo Li

    2009-01-01

    The precipitation of calcium carbonate scale on heat transfer surfaces widely occurs in numerous industrial processes. For the control of calcium carbonate scale and in response to environmental guidelines, the new low phosphonic copolymer was prepared through reaction of maleic anhydride with sodium p-styrene sulfonate in water with redox system of hypophosphorous and hydrogen peroxide as initiator. The anti-scale property

  5. The performance of selected unsaturated coatings for calcium carbonate filler in polypropylene

    Microsoft Academic Search

    Arunee Tabtiang; Richard Venables

    2000-01-01

    The surface of ground calcium carbonate has been modified with several unsaturated acids and acid anhydrides of varying molecular weight. The modified calcium carbonates were then compounded with polypropylene, both in the presence and absence of dicumyl peroxide as an initiator, through twin screw extrusion to give compounds containing 75 phr of filler. Infrared analyses showed that reaction between each

  6. Ink dot formation in coating layer of ink-jet paper with modified calcium carbonate

    Microsoft Academic Search

    Dmitry Ivutin; Toshiharu Enomae; Akira Isogai

    Commercial ink-jet papers are made from silica or alumina as a coating pigment, both of which give high image quality, but are expensive. The present work aims at efficient use of calcium carbonate as an alternative of silica for ink receptive coating layers. Commercial calcium carbonate was ground mechanically or dissolved partially with hydrochloric acid to reduce and equalize the

  7. Habit modification of calcium carbonate in the presence of malic acid

    SciTech Connect

    Mao Zhaofeng [Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Huang Jianhua [Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)], E-mail: jhhuang@zstu.edu.cn

    2007-02-15

    The ability of malic acid to control calcium carbonate morphology has been investigated by aging calcium chloride solution in the presence of urea in a 90 deg. C bath. Malic acid favors the formation of calcite. A transition from single block to aggregate with special morphology occurs upon increasing malic acid concentration. The morphological development of CaCO{sub 3} crystal obviously depends on the starting pH. CaCO{sub 3} crystal grows from spindle seed to dumbbell in the pH regime from 7 to 11; while it evolves from spindle seed, through peanut, to sphere at pH=11.5. Both dumbbell and sphere consist of rods that are elongated along c-axis and capped with three smooth, well-defined rhombic {l_brace}1 0 4{r_brace} faces. A tentative growth mechanism is proposed based on the fractal model suggested by R. Kniep and S. Busch [Angew. Chem. Int. Ed. Engl. 35 (1996) 2624]. - Graphical abstract: Dumbbell-like CaCO{sub 3} particles obtained in the presence of malic acid.

  8. Liquid Crystal Orientation on Carbon Fibers

    Microsoft Academic Search

    P. M. Adams; J. J. Mallon

    1991-01-01

    The orientation of 4-methoxybenzylidene-4?-n-butylaniline (MBBA) on four different carbon fibers has been investigated by X-ray diffraction. The diffraction patterns show that the MBBA liquid crystal is oriented in the direction of the fiber for all of the fibers studied. Scanning electron microscopy (SEM) of the fiber surfaces reveals grooves along the fiber axis which may cause orientation of the MBBA.

  9. Chemical controls on the magnesium content of amorphous calcium carbonate

    NASA Astrophysics Data System (ADS)

    Blue, C. R.; Dove, P. M.

    2015-01-01

    Amorphous calcium carbonate (ACC) is a metastable phase that forms in diverse biogeochemical settings. This material can incorporate significant amounts of magnesium and other elements, but the conditions that regulate composition are not established. Using a mixed flow reactor method, we synthesize Mg-free ACC (control) and amorphous magnesium calcium carbonate (ACMC) under controlled chemical conditions to determine the relationship between composition and inorganic solution chemistry. Input solutions contained a constant initial Mg/Ca ratio of 5/1 with variable total carbonate concentration, pH, and supersaturation. Within the reactor, input solution chemistry evolves in proportion to the extent of precipitation whereby the initial Mg/Ca ratio increases to values as high as 14 at steady state conditions. By this approach, we produce reproducible quantities of ACMC with 24 to >70 mol% Mg to give compositions of Mg(0.24-0.72)Ca(0.76-0.28)CO3·1.42-1.63H2O. The primary control on ACMC composition is the steady state solution composition that develops in the reactor during precipitation. Analysis of the data shows the Mg content of ACMC is regulated by the interplay of three factors at steady state conditions: (1) Mg/Ca ratio; (2) total carbonate concentration; and (3) solution pH. Using the Henderson-Kracek model to estimate the partition coefficients for the Mg content of ACMC, we find KD is approximately constant at 0.047 ± 0.003 when steady state pH is less than 9.5, but values of KD triple as steady state pH increases from 9.5 to 10.3. Our KD values are lower than previous estimates that are based upon initial solution composition. In contrast, our estimates of KD are determined from the solution chemistry at steady state conditions and for pH conditions that are less extreme than previous experimental studies. We suggest the approach of using steady state composition to estimate KD gives a more accurate representation of relationships between ACMC composition and local conditions. The findings demonstrate local pH and total carbonate concentration can be regulated at the time of formation to produce Mg amorphous carbonates of a designated composition.

  10. Tuning calcium carbonate growth through physical confinement and templating with amyloid-like polypeptide aggregates

    NASA Astrophysics Data System (ADS)

    Colaco, Martin Francis

    The creation of useful composite materials requires precise control of the interface between the components in order to tune the overall shape and material properties. Despite the current research into nanotechnology, our ability to create materials with nanoscale precision is nascent. However, nature has a paradigm for the creation of finely structured composites under mild conditions called biomineralization. Through control of protein template assembly, solution conditions, and physical confinement, organisms are able to create useful optical and structural materials, such as bones, teeth, and mollusk shells. The objective of this thesis is to elucidate the importance of these various controls in synthetic systems to further our ability to create nanostructured materials. We begin by examining the formation of self-assembled monolayers (SAMs) of organosilanes on silica oxides. The formation of functionalized surfaces can help control the mineralization of amorphous or crystalline calcium carbonate. Long-chained organosilanes organize on surfaces to form dense, solid-like films, with the terminal groups determining the hydrophobicity and stereochemistry of the film. Our work has shown that uniform hydrophobic and hydrophilic films can be formed by using cleaned silica over glass or mica and through a vapor phase reaction over a liquid one. Additionally, we showed that mixed SAMs with phase-separated domains could be created through the selection of organosilanes and reaction conditions. We have built on these functionalized surfaces through the use of microfabrication and a gas permeable polymer to create three-dimensionally confined microcrystallizers. Other researchers have shown that one-dimensional confinement with a multi-functional surface (patterned with a small nucleating ordered region in a disordered SAM) can stabilize the creation of an amorphous calcium carbonate film before a single, large, micropatterned crystal is grown. Our work has determined that this methodology does not extend to three-dimensional confined systems, as the water has no method of escape. Through the addition of an insoluble hydroscopic polymer to our microreactors, amorphous calcium carbonate of controllable sizes can be grown. However, crystalline calcium carbonate cannot be grown without some type of templating. Studies of calcium carbonate templating have predominantly been performed on SAMs or in poorly characterized gels or protein films. The use of ordered protein or polypeptide aggregates for templating permits both geometry and charge surface density to be varied. We have studied the kinetics and final morphology of ordered aggregates of poly-L-glutamic acid and a copolymer of glutamic acid and alanine through experiments and simulations. Electrostatics, not structure, of the monomer appeared to be the dominating factor in the aggregation, as pH and salt concentration changes led to dramatic changes in the kinetics. Examining our experimental with existing models provided inconsistent results, so we developed a new model that yielded physically realistic rate constants, while generating better fits with longer lag phases and faster growths. However, despite the similarity of aggregation conditions, the two polypeptides yielded vastly different morphologies, with the PEA forming typical amyloid-like fibrils and PE forming larger, twisted lamellar aggregates. Templating with these aggregates also yielded dramatically different patterns. Polycrystalline rhombohedral calcite with smooth faces and edges grew on PEA fibrils, with minimal templating in evidence. However, on PE, numerous calcite crystals with triangular projections tracked the surface of the aggregate. The PE lamellae are characterized by extensive beta-sheet structure. In this conformation, the glutamic acid spacings on the surface of the aggregates can mimic the spacings of the carboxylates in the calcite lattice. In addition, the high negative charge density on the polypeptide surface led to a large number of nucleation sites. As the crystals grow, they impinge on

  11. Gas-flushed packaging contributes to calcium lactate crystals in Cheddar cheese.

    PubMed

    Agarwal, S; Costello, M; Clark, S

    2005-11-01

    Gas-flushed packaging is commonly used for cheese shreds and cubes to prevent aggregation and loss of individual identity. Appearance of a white haze on cubed cheese is unappealing to consumers, who may refrain from buying, resulting in lost revenue to manufacturers. The objective of this study was to determine whether gas flushing of Cheddar cheese contributes to the occurrence of calcium lactate crystals (CLC). Cheddar cheese was manufactured using standard methods, with addition of starter culture, annatto, and chymosin. Two different cheese milk compositions were used: standard (lactose:protein = 1.47, protein:fat = 0.90, lactose = 4.8%) and ultrafiltered (UF; lactose:protein = 1.23, protein:fat = 0.84, lactose = 4.8%), with or without adjunct Lactobacillus curvatus. Curds were milled when whey reached 0.45% titratable acidity, and pressed for 16 h. After aging at 7.2 degrees C for 6 mo, cheeses were cubed (1 x 1 x 4 cm) and either vacuum-packaged or gas-flushed with carbon dioxide, nitrogen, or a 50:50 mixture of carbon dioxide and nitrogen, then aged for an additional 3 mo. Heavy crystals were observed on surfaces of all cubed cheeses that were gas-flushed, but not on cheeses that were vacuum-packaged. Cheeses without Lb. curvatus exhibited L(+)-CLC on surfaces, whereas cheeses with Lb. curvatus exhibited racemic mixtures of L(+)/D(-)-CLC throughout the cheese matrices. The results show that gas flushing (regardless of gas composition), milk composition, and presence of nonstarter lactic acid bacteria, can contribute to the development of CLC on cheese surfaces. These findings stress the importance of packaging to cheese quality. PMID:16230683

  12. Calcium absorbability from milk products, an imitation milk, and calcium carbonate

    SciTech Connect

    Recker, R.R.; Bammi, A.; Barger-Lux, M.J.; Heaney, R.P.

    1988-01-01

    Whole milk, chocolate milk, yogurt, imitation milk (prepared from dairy and nondairy products), cheese, and calcium carbonate were labeled with /sup 45/Ca and administered as a series of test meals to 10 healthy postmenopausal women. Carrier Ca content of the test meals was held constant at 250 mg and subjects fasted before each meal. The absorbability of Ca from the six sources was compared by measuring fractional absorption by the double isotope method. The mean absorption values for all six sources were tightly clustered between 21 and 26% and none was significantly different from the others using one-way analysis of variance. We conclude that none of the sources was significantly superior or inferior to the others.

  13. Fasudil prevents calcium oxalate crystal deposit and renal fibrogenesis in glyoxylate-induced nephrolithic mice.

    PubMed

    Hu, Haiyan; Chen, Wei; Ding, Jiarong; Jia, Meng; Yin, Jingjing; Guo, Zhiyong

    2015-04-01

    Nephrolithiasis is a common kidney disease and one of the major causes of chronic renal insufficiency. We develop and utilize a glyoxylate induced mouse model of kidney calcium oxalate crystal deposition for studying the pharmacological effects of fasudil, a Rho associated protein kinase (ROCK) specific inhibitor, on the kidney injury and fibrosis caused by calcium oxalate crystallization and deposition. Glyoxylate was administrated intraperitoneally to C57BL/6J mice for five consecutive days to establish a mouse model of kidney calcium oxalate crystal formation and deposition. The results showed that the protein expression levels of E-cad and Pan-ck were lower, and the protein expression levels of ?-SMA and Vim were higher, in the kidney tissue of the glyoxylate induced model mice compared with the control mice. The changes in protein expression were weakened when the animals were pretreated with fasudil before glyoxylate administration. Expression of ROCK, PAI-1, and p-Smad proteins in the kidney tissue increased in response to glyoxylate treatment, and the increase was eased when the animals were pretreated with fasudil. Expression of Smad2 and Smad3 in the kidney tissue remained unchanged after glyoxylate administration. Cell apoptosis and proliferation in the kidney cortex and medulla were enhanced in response to the glyoxylate induced calcium oxalate crystal formation and deposition, and fasudil pre-treatment was able to attenuate the enhancement. The results suggest that Fasudil reduces the glyoxylate induced kidney calcium crystal formation and deposition and slows down the kidney fibrogenesis caused by calcium crystal deposition. The possible mechanism may be related the regulatory effects on Rho/ROCK signal transduction and epithelial-mesenchymal transition (EMT). PMID:25697583

  14. Experimental investigation of factors controlling the calcium carbonate ion activity product of shallow water carbonate-rich sediments

    E-print Network

    Bernstein, Lawrence Douglas

    1983-01-01

    sediment samples with sea- water to gain an equilibrium solubility product for calcium carbonate. He failed to recognize that this would represent a metastable equilibrium due to the complex nature of the sediments. Dynamic processes...EXPERIMENTAL INVESTIGATION OF FACTORS CONTROLLING THE CALCIUM CARBONATE ION ACTIVITY PRODUCT OF SHALLOW WATER CARBONATE-RICH SEDIMENTS A Thesis by LAWRENCE DOUGLAS BERNSTEIN Submitted to the Graduate College of Texas A&M University...

  15. 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

  16. Abstract No Hung0356 A P-XANES Study of Phosphate Sorption to Gibbsite and Calcium Carbonate

    E-print Network

    Sparks, Donald L.

    Abstract No Hung0356 A P-XANES Study of Phosphate Sorption to Gibbsite and Calcium Carbonate S solution and freeze-dried. Samples of phosphate sorbed to calcium carbonate were prepared in a similar sorbed to calcium carbonate at pH 8 (Fig. 1) show 2.14 2.16 2.18 2.20 normalizedabsorbance

  17. Effect of mineralogy, salinity, and temperature on Li/Ca and Li isotope composition of calcium carbonate

    E-print Network

    Henderson, Gideon

    during growth of calcium carbonate. This study improves such understanding with two sets of new). This suggests little biological control during Li incorporation into biogenic calcium carbonates. The difference­15 www.elsevier.com/locate/chemgeo #12;1. Introduction Natural calcium carbonate may provide an archive

  18. Effet de l'apport de phosphore, de carbonate de calcium et d'oligo-lments (Cu, Mn, Zn, B)

    E-print Network

    Paris-Sud XI, Université de

    Agronomie Effet de l'apport de phosphore, de carbonate de calcium et d'oligo-éléments (Cu, Mn, Zn apports de phosphore, de carbonate de calcium et d'oligo-éléments (Mn, Cu, Zn, B), en vue de mieux celles de B lorsqu'on élève le pH par apport de carbonate de calcium; - l'accumulation préférentielle de

  19. 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.

  20. Electron paramagnetic resonance study of vanadyl ion doped in ?-calcium formate single crystal

    NASA Astrophysics Data System (ADS)

    Umar, M.; Singh, R. J.; Chand, Prem; Upreti, G. C.

    Results of an EPR study of vanadyl ion (VO 2+) doped in single crystals of ?-calcium formate are reported. Impurity sites in the unit cell and the molecular structure of the vanadyl complexes in the crystal are discussed. The spin-Hamiltonian parameters are determined from single-crystal EPR data at room temperature and from powder EPR data at room temperature and at liquid nitrogen temperature. The g and A tensors are found to be axially symmetric. From the optical and EPR data, the MO bonding coefficients and crystal field parameters are calculated and discussed. Two distinct vanadyl complexes at substitutional sites (Ca 2+) and one interstitial vanadyl complex have been identified.

  1. The Influence of pH on the Oxygen Isotope Composition of Calcium Carbonate

    NASA Astrophysics Data System (ADS)

    Hunt, J. D.; Watkins, J. M.; Ryerson, F. J.; DePaolo, D. J.

    2013-12-01

    Oxygen isotope fractionation between calcium carbonate and water is temperature-dependent and can therefore be used as a paleothermometer. Although oxygen isotope fractionation is expected from principles of equilibrium isotopic partitioning, the temperature-dependence remains uncertain because other factors, such as slow exchange between dissolved inorganic carbon (DIC) species and water, can obscure the temperature signal. Oxygen isotopic equilibrium between aqueous solution and calcium carbonate includes two distinct equilibria: equilibrium of the DIC species in solution (i.e., CO2(aq), H2CO3, HCO3-, and CO32-) with water, and equilibrium between the dissolved inorganic carbon with the precipitated carbonate. To isolate kinetic isotope effects that arise at the mineral-solution interface, isotopic equilibrium among DIC species must be maintained. This can be accomplished by dissolving the enzyme carbonic anhydrase (CA) into the solution, thereby reducing the time required for isotopic equilibration between DIC species by approximately two orders of magnitude between pH 7.7 and 9.3. We conduct calcite growth experiments aimed specifically at measuring the pH-dependence of kinetic oxygen isotope effects during precipitation of calcite. We precipitated calcite from aqueous solution at a constant pH and controlled supersaturation over the pH range 7.7-9.3. For each experiment, a gas mixture of N2 and CO2 is constantly bubbled through a beaker containing ~1300 mL of solution (30 mM CaCl2 + 5 mM NH4Cl + 0.1 mM SrCl2). As CO2 from the gas dissolves into solution, calcite crystals grow on the beaker walls. The pH of the solution is maintained by use of an autotitrator with NaOH as the titrant. We control the temperature, pH, the pCO2 of the gas inflow, and the gas inflow rate, and monitor the total alkalinity, the pCO2 of the gas outflow, and the amount of NaOH added. A constant crystal growth rate of ~1.6 mmol/m2/hr is maintained over all experiments. We will present results from this set of experiments and discuss kinetic oxygen isotope effects in the context of a recently-developed ion-by-ion growth model of calcite.

  2. Design of a continuous process setup for precipitated calcium carbonate production from steel converter slag.

    PubMed

    Mattila, Hannu-Petteri; Zevenhoven, Ron

    2014-03-01

    A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ?75?L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup. PMID:24578147

  3. Molecular mechanism of crystallization impacting calcium phosphate cements

    SciTech Connect

    Giocondi, J L; El-Dasher, B S; Nancollas, G H; Orme, C A

    2009-05-31

    In summary, SPM data has shown that (1) Mg inhibits growth on all steps but relatively high Mg/Ca ratios are needed. Extracting the mechanism of interaction requires more modeling of the kinetic data, but step morphology is consistent with incorporation. (2) Citrate has several effects depending on the citrate/Ca ratio. At the lowest concentrations, citrate increases the step free energy without altering the step kinetics; at higher concentrations, the polar step is slowed. (3) Oxalate also slows the polar step but additionally stabilizes a new facet, with a [100]{sub Cc} step. (4) Etidronate has the greatest kinetic impact of the molecules studied. At 7{micro}M concentrations, the polar step slows by 60% and a new polar step appears. However, at the same time the [10-1]{sub Cc} increases by 67%. It should be noted that all of these molecules complex calcium and can effect kinetics by altering the solution supersaturation or the Ca to HPO{sub 4}{sup 2-} ratio. For the SPM data shown, this effect was corrected for to distinguish the effect of the molecule at the crystal surface from the effect of the molecule on the solution speciation. The goal of this paper is to draw connections between fundamental studies of atomic step motion and potential strategies for materials processing. It is not our intent to promote the utility of SPM for investigating processes in cement dynamics. The conditions are spectacularly different in many ways. The data shown in this paper are fairly close to equilibrium (S=1.6) whereas the nucleation of cements is initiated at supersaturation ratios in the thousands to millions. Of course, after the initial nucleation phase, the growth will occur at more modest supersaturations and as the cement evolves towards equilibrium certainly some of the growth will occur in regimes such as shown here. In addition to the difference in supersaturation, cements tend to have lower additive to calcium ratios. As an example, the additive to Ca ratio is {approx}10{sup -3} to 10{sup -4} for a pyrophosphate based cement (Grover et al., 2006). Where the in situ SPM approach provides unique insights is in providing details of where and how molecules inhibit or accelerate kinetics. This has the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. For example, it is unlikely that bulk techniques could deduce the simultaneous acceleration and inhibition effects of etidronate; or that citrate reduced growth rate by altering step density rather than step speed. In addition, SPM data translates to tractable questions for modelers. The questions changes from 'How does etidronate inhibit brushite growth?' to 'Why does etidronate bind strongly to the [101]{sub Cc} step while it doesn't to the [10-1]{sub Cc} step?' This is still a challenging question but it is far better defined. Given that step chemistries are generally different, it seems reasonable to expect that the greatest inhibition will be achieved not with one, but with several synergistically chosen additives. For example, the most effective growth inhibitors for brushite would target the two fast steps, namely the non-polar, [10-1]{sub Cc} and the polar, [101]{sub Cc} steps. Several molecules have been shown to slow the polar step, with etidronate as the most dramatic example. By contrast, only Mg was observed to slow the [10-1]{sub Cc} step. Thus, a combination of high concentrations of Mg to target the [10-1]{sub Cc} step with low concentrations of etidronate to target the polar steps, should be a more effective combination than either alone. However Mg is not a particularly good inhibitor in the sense that high concentrations are needed, and it is not specific. More ideally, an inhibitor would be designed to interact specifically with the [10-1] step, which would allow the two steps to be independently modified. Again, this provides an opportunity for tighter coupling with theoretical modeling. The question changes from 'What types of molecules will inhibit brushite growth' to 'What type of molecule

  4. Dissolution rate of calcium carbonate in high pCO2 seawater under high pressure

    Microsoft Academic Search

    N. Tsurushima; M. Suzumura; N. Yamada; K. Harada

    2008-01-01

    To understand how the dissolution rate of calcium carbonate changes, laboratory experiments were conducted under high pressure and high pCO2 condition. As a result, rapid dissolution was observed at above 5000 ppm of pCO2. The initial dissolution rates of the well correlated with initial concentration of dissolved inorganic carbon. Dissolution rate were generally decreased with time. Dissolution of calcium carbonate

  5. Tensile strength of sand, palygorskite and calcium carbonate mixtures and interpretation with the effective stress theory

    Microsoft Academic Search

    M. R. Mosaddeghi; M. A. Hajabbasi; H. Khademi

    2006-01-01

    Many soils in arid regions of the world including those of central Iran contain palygorskite and carbonates in their mineral fraction. There is, however, little information on the effects of these minerals on soil physical and mechanical behaviour. A laboratory experiment was carried out to evaluate tensile strength of artificial mixtures of sand–palygorskite–calcium carbonate (CaCO3). Palygorskite and calcium carbonate were

  6. Carbothermic reduction of zinc sulfide in the presence of calcium carbonate

    Microsoft Academic Search

    Che-Ming Wu; Chun-I Lin; Hsi-Kuei Chen

    2006-01-01

    Carbothermic reduction of zinc sulfide in the presence of calcium carbonate was investigated by employing an X-ray diffractometer\\u000a (XRD), a carbon and sulfur determinator, a scanning electron microscope (SEM), an energy-dispersive X-ray analysis (EDX),\\u000a and a surface area analyzer. Experimental results revealed that calcium carbonate was completely decomposed to CaO in the\\u000a initial stage and CaO was then involved in

  7. Chemical, microstructural and strength development of calcium and magnesium carbonate binders

    Microsoft Academic Search

    P. De Silva; L. Bucea; V. Sirivivatnanon

    2009-01-01

    The influence of magnesium on the chemistry of calcium carbonate formation has been studied. It was found that the type of carbonate formed by subjecting compacts of Ca(OH)2 and Mg(OH)2 to carbon dioxide (up to 20 atm CO2 pressure) for variable periods of time is largely controlled by the molar proportion of calcium to magnesium in the initial mixture. Increasing magnesium

  8. Preparation and characteristics of calcium carbonate\\/silica nanoparticles with core-shell structure

    Microsoft Academic Search

    Hari Bala; Yishun Zhang; Haibin Ynag; Chengyu Wang; Minggang Li; Xiaotang Lv; Zichen Wang

    2007-01-01

    In this paper, a step-by-step (SBS) method was used to prepare calcium carbonate\\/silica nanoparticles with core-shell structure. The core of calcium carbonate nanoparticles were cubic shaped with an average size of 48nm obtained in the first step of carbonation method and the shell of SiO2 with thickness about 5nm were coated on the core in the second step of sol-precipitation

  9. Crystallization behaviour of hydroxide cobalt carbonates by aging: Environmental implications.

    NASA Astrophysics Data System (ADS)

    González-López, Jorge; Fernández-González, Angeles; Jimenez, Amalia

    2014-05-01

    Cobalt is a naturally occurring element widely distributed in water, sediments and air that is essential for living species, since it is a component of B12 vitamin and it is also a strategic and critical element used in a number of commercial, industrial and military applications. However, relatively high accumulations of cobalt in environment can be toxic for human and animal health. Cobalt usually occurs as Co2+ and Co3+ in aqueous solutions, where Co2+ is the most soluble and hence its mobility in water is higher. The study of the precipitation of cobalt carbonates is of great interest due to the abundance of carbonate minerals in contact with surface water and groundwater which can be polluted with Co2+. Previous works have demonstrated that the formation of Co-bearing calcium carbonates and Co-rich low crystallinity phases takes place at ambient conditions. With the aim of investigating the crystallization behavior of Co- bearing carbonates at ambient temperature, macroscopic batch-type experiments have been carried out by mixing aqueous solutions of CoCl2 (0.05M) and Na2CO3 (0.05M) during increasing reaction times (5 minutes and 1, 5, 24, 48, 96, 168, 720 and 1440 hours). The main goals of this work were (i) to analyse the physicochemical evolution of the system and (ii) to study the evolution of the crystallinity of the solid phases during aging. After a given reaction period, pH, alkalinity and dissolved Co2+ in the aqueous solutions were analysed. The evolution of the morphology and chemical composition of the solids with aging time was examined by SEM and TEM. The precipitates were also analyzed by X-ray powder diffraction (XRD) and the crystallinity degree was followed by the intensity and the full width at high medium (FWHM) of the main peaks. The results show that a low crystallinity phase was obtained at the very beginning of aging. This phase evolves progressively to form hydroxide carbonate cobalt (Co2CO3(OH)2) which crystallize with the spatial group P21/a (monoclinic system) after about 4 days. At the same time, the most important fall of cobalt content takes place, but pH and alkalinity values do not show significant changes. The evolution of the aqueous solutions is closely related to the increases of crystallinity degree. TEM study confirms the evolution of the shape of crystals, which exhibit platelet morphology at the end of aging time.

  10. Peptides of Matrix Gla Protein Inhibit Nucleation and Growth of Hydroxyapatite and Calcium Oxalate Monohydrate Crystals

    PubMed Central

    Goiko, Maria; Dierolf, Joshua; Gleberzon, Jared S.; Liao, Yinyin; Grohe, Bernd; Goldberg, Harvey A.; de Bruyn, John R.; Hunter, Graeme K.

    2013-01-01

    Matrix Gla protein (MGP) is a phosphorylated and ?-carboxylated protein that has been shown to prevent the deposition of hydroxyapatite crystals in the walls of blood vessels. MGP is also expressed in kidney and may inhibit the formation of kidney stones, which mainly consist of another crystalline phase, calcium oxalate monohydrate. To determine the mechanism by which MGP prevents soft-tissue calcification, we have synthesized peptides corresponding to the phosphorylated and ?-carboxylated sequences of human MGP in both post-translationally modified and non-modified forms. The effects of these peptides on hydroxyapatite formation and calcium oxalate crystallization were quantified using dynamic light scattering and scanning electron microscopy, respectively. Peptides YGlapS (MGP1-14: Y?EpSHEpSMEpSYELNP), YEpS (YEpSHEpSMEpSYELNP), YGlaS (Y?ESHESMESYELNP) and SK-Gla (MGP43-56: SKPVH?ELNR?EACDD) inhibited formation of hydroxyapatite in order of potency YGlapS > YEpS > YGlaS > SK-Gla. The effects of YGlapS, YEpS and YGlaS on hydroxyapatite formation were on both crystal nucleation and growth; the effect of SK-Gla was on nucleation. YGlapS and YEpS significantly inhibited the growth of calcium oxalate monohydrate crystals, while simultaneously promoting the formation of calcium oxalate dihydrate. The effects of these phosphopeptides on calcium oxalate monohydrate formation were on growth of crystals rather than nucleation. We have shown that the use of dynamic light scattering allows inhibitors of hydroxyapatite nucleation and growth to be distinguished. We have also demonstrated for the first time that MGP peptides inhibit the formation of calcium oxalate monohydrate. Based on the latter finding, we propose that MGP function not only to prevent blood-vessel calcification but also to inhibit stone formation in kidney. PMID:24265810

  11. Calcium Oxalate Crystals: An Integral Component of the Sclerotinia sclerotiorum/Brassica carinata Pathosystem

    PubMed Central

    Uloth, Margaret B.; Clode, Peta L.; You, Ming Pei; Barbetti, Martin J.

    2015-01-01

    Oxalic acid is an important virulence factor for disease caused by the fungal necrotrophic pathogen Sclerotinia sclerotiorum, yet calcium oxalate (CaOx) crystals have not been widely reported. B. carinata stems were infected with S. sclerotiorum and observed using light microscopy. Six hours post inoculation (hpi), CaOx crystals were evident on 46% of stem sections and by 72 hpi on 100%, demonstrating that the secretion of oxalic acid by S. sclerotiorum commences before hyphal penetration. This is the first time CaOx crystals have been reported on B. carinata infected with S. sclerotiorum. The shape of crystals varied as infection progressed. Long tetragonal rods were dominant 12 hpi (68% of crystal-containing samples), but by 72 hpi, 50% of stems displayed bipyramidal crystals, and only 23% had long rods. Scanning electron microscopy from 24 hpi revealed CaOx crystals in all samples, ranging from tiny irregular crystals (< 0.5 ?m) to large (up to 40 ?m) highly organized arrangements. Crystal morphology encompassed various forms, including tetragonal prisms, oval plates, crystal sand, and druses. Large conglomerates of CaOx crystals were observed in the hyphal mass 72 hpi and these are proposed as a strategy of the fungus to hold and detoxify Ca2+ions. The range of crystal morphologies suggests that S. sclerotiorum growth and infection controls the form taken by CaOx crystals. PMID:25816022

  12. Calcium Oxalate Crystals: An Integral Component of the Sclerotinia sclerotiorum/Brassica carinata Pathosystem.

    PubMed

    Uloth, Margaret B; Clode, Peta L; You, Ming Pei; Barbetti, Martin J

    2015-01-01

    Oxalic acid is an important virulence factor for disease caused by the fungal necrotrophic pathogen Sclerotinia sclerotiorum, yet calcium oxalate (CaOx) crystals have not been widely reported. B. carinata stems were infected with S. sclerotiorum and observed using light microscopy. Six hours post inoculation (hpi), CaOx crystals were evident on 46% of stem sections and by 72 hpi on 100%, demonstrating that the secretion of oxalic acid by S. sclerotiorum commences before hyphal penetration. This is the first time CaOx crystals have been reported on B. carinata infected with S. sclerotiorum. The shape of crystals varied as infection progressed. Long tetragonal rods were dominant 12 hpi (68% of crystal-containing samples), but by 72 hpi, 50% of stems displayed bipyramidal crystals, and only 23% had long rods. Scanning electron microscopy from 24 hpi revealed CaOx crystals in all samples, ranging from tiny irregular crystals (< 0.5 ?m) to large (up to 40 ?m) highly organized arrangements. Crystal morphology encompassed various forms, including tetragonal prisms, oval plates, crystal sand, and druses. Large conglomerates of CaOx crystals were observed in the hyphal mass 72 hpi and these are proposed as a strategy of the fungus to hold and detoxify Ca2+ions. The range of crystal morphologies suggests that S. sclerotiorum growth and infection controls the form taken by CaOx crystals. PMID:25816022

  13. Biomimetic growth of calcium oxalate crystals: synchrotron X-ray studies

    NASA Astrophysics Data System (ADS)

    Uysal, Ahmet; Stripe, Benjamin; Dutta, Pulak

    2010-03-01

    Oriented crystals of calcium oxalate monohydrate (COM) form one of the major constituents of kidney stones in humans, and these crystals are also found in many plants. It is widely accepted that an organic matrix of lipids and proteins is involved in the crystallization of COM, though their role is not well-understood [1]. Langmuir monolayers of lipids on supersaturated aqueous solutions can be used to mimic the lipid-crystal interface during mineralization. We have studied nucleation and growth of COM crystals under heneicosanoic acid monolayers at the air-water interface. We used synchrotron x-rays in the grazing incidence geometry to determine the structure of the organic monolayer and the orientation of COM crystals in-situ during crystallization. We see that the (-101) faces of COM crystals are parallel to the organic matrix. There is a commensurate relationship between the heneicosanoic acid monolayer and the (-101) crystal face that may be responsible from the oriented growth. Evolution of the monolayer structure with time will be described. [1]S. R. Khan, Calcium Oxalate in Biological Systems, CRC Press, Boca Raton, 1995

  14. Textural properties of synthetic nano-calcite produced by hydrothermal carbonation of calcium hydroxide

    E-print Network

    Montes-Hernandez, German; Charlet, L; Tisserand, Delphine; Renard, F

    2008-01-01

    The hydrothermal carbonation of calcium hydroxide (Ca(OH)2) at high pressure of CO2 (initial PCO2 1/4 55 bar) and moderate to high temperature (30 and 90 1C) was used to synthesize fine particles of calcite. This method allows a high carbonation efficiency (about 95% of Ca(OH)2-CaCO3 conversion), a significant production rate (48 kg/m3 h) and high purity of product (about 96%). However, the various initial physicochemical conditions have a strong influence on the crystal size and surface area of the synthesized calcite crystals. The present study is focused on the estimation of the textural properties of synthesized calcite (morphology, specific surface area, average particle size, particle size distribution and particle size evolution with reaction time), using Rietveld refinements of X-ray diffraction (XRD) spectra, Brunauer-Emmett-Teller (BET) measurements, and scanning electron microscope (SEM) and transmission electron microscope (TEM) observations. This study demonstrate that the pressure, the temperatu...

  15. Coupled dissolution-precipitation as a mechanism for amorphous-to-crystalline calcium carbonate phase transition

    NASA Astrophysics Data System (ADS)

    Rodriguez-Navarro, Carlos Manuel; Kud?acz, Krzysztof; Ruiz-Agudo, Encarnacion

    2014-05-01

    Growing evidence shows that several calcium carbonate biominerals form via an amorphous precursor phase. Such a biomineralization strategy could also be applicable for the biomimetic synthesis of novel functional materials. A crucial step in this process is the transformation of amorphous calcium carbonate (ACC) into calcite. However, controversy exists as to what is the actual mechanism of this transformation: Is it a solid-solid (solid state) or a dissolution/precipitation mechanism? Determining the transition mechanism is critical for example in interpreting the formation of oriented crystalline structures in biominerals (e.g., echinoderm spicles). We studied calcium carbonate precipitation and phase transitions according to the overall reaction Ca(OH)2 + CO2 = CaCO3+ H2O. Mineral phase transformations during this reaction were studied using transmission electron microscopy (TEM). Our TEM analysis showed that two different types of ACC are sequentially formed during this reaction. Type I ACC shows no well-defined short-range order, while Type II ACC shows a short-range order corresponding to calcite. Following e-beam irradiation, Type I ACC particles transform into randomly oriented CaO nanocrystals, while irradiation of Type II ACC leads to the formation of pseudomorphs made up of perfectly oriented aggregates of calcite nanocrystals. Moreover, calcite crystals formed in solution or in air (85 % relative humidity) after Type II ACC are also pseudomorphs made up of porous aggregates of preferentially oriented calcite nanocrystals. Our results give experimental evidence showing that the ACC to calcite transformation under relevant biomineralization conditions (low T and P), also applicable in the biomimetic synthesis of calcite, is a pseudomorphic dissolution-precipitation process. This mechanism involves the tightly interface-coupled dissolution of the precursor amorphous phase (with the crystalline phase protostructure) and concomitant deposition of the crystalline product (calcite) on the remaining (not fully dissolved) precursor phase via epitaxial crystallization. The solubility and molar volume differences between parent and product phase explain the generation of porosity, which enables the progress of the reaction leading to a calcite pseudomorph.

  16. Synthesis and thermal behavior of well-crystallized calcium-deficient phosphate apatite

    Microsoft Academic Search

    Anne Mortier; Jacques Lemaitre; Luc Rodrique; Paul G. Rouxhet

    1989-01-01

    Large crystals (0.5 × 0.5 × 10 mum) of calcium-deficient hydroxyapatites (DAp's) have been synthesized by aqueous precipitation under controlled conditions of pH and temperature. The samples have been characterized using chemical analysis, temperature-programmed dehydration (TPR). X-ray diffraction, IR spectroscopy, and transmission electron microscopy. They show that very well-crystallized DAp's with Ca\\/P close to 1.50 can be obtained under well-selected

  17. Controlled synthesis of crystalline calcium carbonate aggregates with unusual morphologies involving the phase transformation from amorphous calcium carbonate

    SciTech Connect

    Tang Hua [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China); Yu Jiaguo [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China)], E-mail: jiaguoyu@yahoo.com; Zhao Xiufeng [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122, Wuhan 430070 (China)

    2009-04-02

    Peanut-shaped CaCO{sub 3} aggregates, featured of two dandelion-like heads built up from rod-like subunits, have been synthesized via a facile precipitation reaction between Na{sub 2}CO{sub 3} and CaCl{sub 2} at ambient temperature in the presence of magnesium ions and ethanol solvent. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results show that a high magnesium concentration and ethanol solvent are necessary for the formation of the unusual peanut-like aggregates. In addition, a multistep phase transformation process from amorphous calcium carbonate (ACC) to a mixture of ACC and calcite and ultimately to calcite and aragonite was observed in the formation process of the unusual structures. A possible mechanism for the formation of the unusual peanut-shape aggregates has been proposed and discussed.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. 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. PMID:16029849

  20. Inhibition and dissolution of calcium oxalate crystals by Berberis Vulgaris-Q and other metabolites

    Microsoft Academic Search

    Ishwar Das; S. K Gupta; V. N Pandey; Shoeb A Ansari

    2004-01-01

    Inhibition and dissolution of calcium oxalate crystals in solutions containing a homoeopathic medicine Berberis Vulgaris-Q, amino acids such as aspartic acid, glutamic acid, ?-keto glutaric acid, a naturally occurring inhibitor and juices of some fruits of citrus group such as lemon, orange and mausammi have been studied. Considerable solubility was observed and found that in each case solubility changes with

  1. Physical characteristics of Medicago truncatula calcium oxalate crystals determine their effectiveness in insect defense

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant structural traits can act as defense against herbivorous insects, causing them to avoid feeding on a given plant or tissue. Mineral crystals of calcium oxalate in leaves of Medicago truncatula Gaertn. have previously been shown to be effective deterrents of lepidopteran insect feeding. They ar...

  2. Characterization of calcium crystals in Abelia using x-ray diffraction and electron microscopes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Localization, chemical composition, and morphology of calcium crystals in leaves and stems of Abelia mosanensis and A. ×grandiflora were analyzed with a variable pressure scanning electron microscope (VP-SEM) equipped with an X-ray diffraction system, low temperature SEM (LT-SEM) and a transmission ...

  3. Calcium

    MedlinePLUS

    ... loss. Some clinical research shows that increasing calcium consumption from dairy products such as yogurt seems to ... and vitamin D. For weight loss, increasing calcium consumption from dairy products to total intake of 500- ...

  4. Calcium

    MedlinePLUS

    ... strong bones and teeth. Why Do I Need Calcium? Bones grow rapidly during adolescence, and teens need ... salmon with bones. Almond milk. Back Continue Working Calcium Into Your Diet Looking for ways to up ...

  5. Calcium

    MedlinePLUS

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy ...

  6. New and unusual forms of calcium oxalate raphide crystals in the plant kingdom.

    PubMed

    Raman, Vijayasankar; Horner, Harry T; Khan, Ikhlas A

    2014-11-01

    Calcium oxalate crystals in higher plants occur in five major forms namely raphides, styloids, prisms, druses and crystal sand. The form, shape and occurrence of calcium oxalate crystals in plants are species- and tissue-specific, hence the presence or absence of a particular type of crystal can be used as a taxonomic character. So far, four different types of needle-like raphide crystals have been reported in plants. The present work describes two new and unusual forms of raphide crystals from the tubers of Dioscorea polystachya--six-sided needles with pointed ends (Type V) and four-sided needles with beveled ends (Type VI). Both of these new types of needles are distinct from the other four types by each having a surrounding membrane that envelopes a bundle of 10-20 closely packed thin crystalline sheets. The previously known four types of needles have solid or homogenous crystalline material, surrounded by a membrane or lamellate sheath called a crystal chamber. Only the Type VI crystals have beveled ends and the needles of the other five types have pointed ends. PMID:25139563

  7. Calcium carbonate corrosivity in an Alaskan inland sea

    NASA Astrophysics Data System (ADS)

    Evans, W.; Mathis, J. T.; Cross, J. N.

    2013-12-01

    Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (?) to levels that are corrosive (i.e. ? ? 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacier melt. To highlight this process, we present carbonate system data collected in May (spring) and September (autumn) starting 2009 through 2012 from Prince William Sound (PWS), a semi-enclosed inland sea located on the south-central coast of Alaska that is ringed with fjords containing tidewater glaciers. Initial sampling in PWS covered limited stations in the western sound, and ? levels corrosive to aragonite, a form of CaCO3, were observed in association with glacial melt during autumn. Beginning in September 2011, expanded sampling spanned the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (< 50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive ? levels seen below the mixed layer depth across the sound, and (2) as point sources for surface plumes of glacial melt with corrosive ? levels (? for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. The cumulative effect of glacial melt is likely responsible for the seasonal widespread reduction of ? in PWS; however, glacial melt-driven CaCO3 corrosivity is poorly reflected by pCO2 or pHT, indicating that any one of those carbonate parameters alone would inadequately track corrosive conditions in PWS. The unique conditions of the carbonate system in the surface glacial melt plumes enhances atmospheric CO2 uptake, which, if not offset by mixing or primary productivity, would exacerbate CaCO3 corrosivity in a positive feedback via ocean acidification. These effects from glacial melt make PWS highly sensitive to climate change and susceptible to amplified CaCO3 corrosivity.

  8. Poly (vinylsulfonic acid) assisted synthesis of aqueous solution stable vaterite calcium carbonate nanoparticles.

    PubMed

    Nagaraja, Ashvin T; Pradhan, Sulolit; McShane, Michael J

    2014-03-15

    Calcium carbonate nanoparticles of the vaterite polymorph were synthesized by combining CaCl2 and Na2CO3 in the presence of poly (vinylsulfonic acid) (PVSA). By studying the important experimental parameters we found that controlling PVSA concentration, reaction temperature, and order of reagent addition the particle size, monodispersity, and surface charge can be controlled. By increasing PVSA concentration or by decreasing temperature CCNPs with an average size from ?150 to 500 nm could be produced. We believe the incorporation of PVSA into the reaction plays a dual role to (1) slow down the nucleation rate by sequestering calcium and to (2) stabilize the resulting CCNPs as the vaterite polymorph, preventing surface calcification or aggregation into microparticles. The obtained vaterite nanoparticles were found to maintain their crystal structure and surface charge after storage in aqueous buffer for at least 5 months. The aqueous stable vaterite nanoparticles could be a useful platform for the encapsulation of a large variety of biomolecules for drug delivery or as a sacrificial template toward capsule formation for biosensor applications. PMID:24461857

  9. Calcium carbonate saturation in the surface water of the Arctic Ocean: undersaturation in freshwater influenced shelves

    Microsoft Academic Search

    M. Chierici; A. Fransson

    2009-01-01

    In the summer of 2005, we sampled surface water and measured pH and total alkalinity (AT) underway aboard IB Oden along the Northwest Passage from Cape Farwell (South Greenland) to the Chukchi Sea. We investigated variability of carbonate system parameters, focusing particularly on carbonate concentration [CO32-] and calcium carbonate saturation states, as related to freshwater addition, biological processes and physical

  10. Distribution of calcium carbonate in surface sediments of the Atlantic Ocean

    Microsoft Academic Search

    P. E. Biscaye; V. Kolla; K. K. Turekian

    1976-01-01

    The areal distribution of calcium carbonate in the surface sediments of the Atlantic Ocean and adjacent seas and oceans is mapped on the basis of over 1700 data points. The first-order relation of carbonate distribution to water depth is evident in both the areal distribution and the plots of carbonate versus depth for 11 areas of the Atlantic. Superimposed on

  11. Face-specific incorporation of osteopontin into urinary and inorganic calcium oxalate monohydrate and dihydrate crystals

    Microsoft Academic Search

    Lauren A. Thurgood; Alison F. Cook; Esben S. Sørensen; Rosemary L. Ryall

    2010-01-01

    Our aim was to examine the attachment to, and incorporation of intact, highly phosphorylated osteopontin (OPN) into inorganic\\u000a (i) and urinary (u) calcium oxalate monohydrate (COM) and dihydrate (COD) crystals. uCOM and uCOD crystals were precipitated\\u000a from ultrafiltered (UF) urine containing human milk OPN (mOPN) labelled with Alexa Fluor 647 fluorescent dye at concentrations\\u000a of 0.1–5.0 mg\\/L. iCOM and iCOD crystals

  12. Evaluation of a routine method for determination of calcium oxalate crystal growth inhibition in diluted urine samples.

    PubMed

    Tiselius, H G; Fornander, A M

    1981-04-01

    We have evaluated a routine method for determination of the inhibition of calcium oxalate crystal growth in diluted urine samples. A crystallization inhibition index is calculated from the decrease in [14C]oxalate concentration in a metastable solution of calcium chloride and sodium oxalate after addition of seed crystals of calcium oxalate. The coefficient of variation between different determinations on the same sample is less than 1.5%, and there is good correspondence between indices obtained by this method and by a more laborious older method. We also studied the influence of different urinary constituents on the crystal growth rate in the system; whereas there was significant inhibition with citrate, chondritin sulfate, and pyrophosphate, no effects were observed with ordinary urinary concentrations of calcium, magnesium, and oxalate. The mean inhibition index was lower in a group of male patients with calcium oxalate stone disease than in a control group of normal men. PMID:7471423

  13. 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.

  14. Inhibition on calcium oxalate crystallization and repair on injured renal epithelial cells of degraded soybean polysaccharide.

    PubMed

    Yao, Xiu-Qiong; Ouyang, Jian-Ming; Peng, Hua; Zhu, Wen-Yu; Chen, He-Qun

    2012-09-01

    This paper investigated the inhibitory effect of degraded soybean polysaccharide (DPS) on the growth of calcium oxalate (CaOxa) crystals. The results were compared with that of soybean polysaccharide without degradation (SPS). The data showed that DPS exhibited a much higher efficiency to inhibit CaOxa growth and stabilize calcium oxalate dihydrate (COD) compared with SPS. As DPS concentration increased, the soluble Ca(2+) ions significantly increased, the aggregation degree of calcium oxalate monohydrate (COM) crystals decreased, the shape of COD crystals became round and blunt, and the Zeta potential on CaOxa crystal surface reduced. The above results were all conducive for the inhibition of CaOxa crystallization. In addition, DPS displayed a distinct repairing effect on oxidative injured renal epithelial cells in African green monkey (Vero), with enhanced cell viability and extracellular superoxide dismutase activity after repair. The morphologies of the repaired cells and their regulatory capability on CaOxa growth were between the control and injured cells. The results indicated that the risk of stone formation can be reduced by DPS, and that DPS may be a potential green drug to prevent the formation of CaOxa stones. PMID:24751057

  15. Biofilm-induced calcium carbonate precipitation: application in the subsurface

    NASA Astrophysics Data System (ADS)

    Phillips, A. J.; Eldring, J.; Lauchnor, E.; Hiebert, R.; Gerlach, R.; Mitchell, A. C.; Esposito, R.; Cunningham, A. B.; Spangler, L.

    2012-12-01

    We have investigated mitigation strategies for sealing high permeability regions, like fractures, in the subsurface. This technology has the potential to, for example, improve the long-term security of geologically-stored carbon dioxide (CO2) by sealing fractures in cap rocks or to mitigate leakage pathways to prevent contamination of overlying aquifers from hydraulic fracturing fluids. Sealing technologies using low-viscosity fluids are advantageous since they potentially reduce the necessary injection pressures and increase the radius of influence around injection wells. In this technology, aqueous solutions and suspensions are used to promote microbially-induced mineral precipitation which can be applied in subsurface environments. To this end, a strategy was developed to twice seal a hydraulically fractured, 74 cm (2.4') diameter Boyles Sandstone core, collected in North-Central Alabama, with biofilm-induced calcium carbonate (CaCO3) precipitates under ambient pressures. Sporosarcina pasteurii biofilms were established and calcium and urea containing reagents were injected to promote saturation conditions favorable for CaCO3 precipitation followed by growth reagents to resuscitate the biofilm's ureolytic activity. Then, in order to evaluate this process at relevant deep subsurface pressures, a novel high pressure test vessel was developed to house the 74 cm diameter core under pressures as high as 96 bar (1,400 psi). After determining that no impact to the fracture permeability occurred due to increasing overburden pressure, the fractured core was sealed under subsurface relevant pressures relating to 457 meters (1,500 feet) below ground surface (44 bar (650 psi) overburden pressure). After fracture sealing under both ambient and subsurface relevant pressure conditions, the sandstone core withstood three times higher well bore pressure than during the initial fracturing event, which occurred prior to biofilm-induced CaCO3 mineralization. These studies suggest biofilm-induced CaCO3 precipitation technologies may potentially seal and strengthen high permeability regions or fractures (either natural or induced) in the subsurface. Novel high pressure test vessel to investigate biogeochemical processes under relevant subsurface scales and pressures.

  16. Growth Rate of Calcite Steps as a Function of Aqueous Calcium-to-Carbonate Ratio: Independent Attachment and Detachment of Calcium and Carbonate Ions

    SciTech Connect

    Stack, Andrew G [ORNL; Grantham, Ms. Meg [Georgia Institute of Technology

    2010-01-01

    Growth rates of monolayer-height steps on the {1014} calcite surface have been measured as a function of the aqueous calcium-to-carbonate ratio. The maximum growth rates of the two common crystallographic orientations were found to deviate from the ideal stoichiometric ratio of 1:1, and dissolution features were observed under supersaturated solutions containing high calcium-to-carbonate ratios. To explain these phenomena, a theory is applied that treats the rates of attachment and detachment of aqueous calcium and carbonate ions separately. The resultant attachment rate constants are 1-3 orders of magnitude smaller than the water exchange rate of the constituent aqueous ions, suggesting that ligand-exchange processes may directly drive attachment. The broader implication is that the saturation state alone is not adequate to fully describe the rates of the multiple, independent reactions that occur on mineral surfaces under these conditions.

  17. Tumoral calcium pyrophosphate dihydrate crystal deposition disease: a rare diagnosis by fine-needle aspiration.

    PubMed

    Kishore, B; Khare, P; Gupta, R Jain; Gupta, C; Khare, V

    2010-01-01

    Calcium pyrophosphate dihydrate crystal deposition disease (CPPD) is a well-recognized inflammatory joint disorder characterized by presence of calcium pyrophosphate dihydrate crystals in intraarticular and periarticular tissue. We report here a case of a 48-year-old male who presented with painless right hand swelling. Clinical suspicion was that of malignant soft tissue tumor. Fine-needle aspiration (FNA) yielded chalky white gritty material. Microscopic examination showed large areas of basophilic calcified material, histiocytes, giant cells and characteristic rhomboid shaped crystals. At places, chondroid material was also identified, hence, diagnosis of CPPD was made. This was confirmed on histopathological examination. Tophaceous/ tumoral pseudogout is a rare form of CPPD and it is important to recognize that this form can be diagnosed in FNA cytology (FNAC) and misdiagnosis of benign or malignant cartilaginous lesions can be avoided. PMID:19688761

  18. Solubility, inhibition of crystallization and microscopic analysis of calcium oxalate crystals in the presence of fractions from Humulus lupulus L.

    NASA Astrophysics Data System (ADS)

    Fr?ckowiak, Anna; Ko?lecki, Tomasz; Skibi?ski, Przemys?aw; Gawe?, Wies?aw; Zaczy?ska, Ewa; Czarny, Anna; Piekarska, Katarzyna; Gancarz, Roman

    2010-11-01

    Procedures for obtaining noncytotoxic and nonmutagenic extracts from Humulus lupulus L. of high potency for inhibition and dissolving of model (calcium oxalate crystals) and real kidney stones, obtained from patients after surgery, are presented. Multistep extraction procedures were performed in order to obtain the preparations with the highest calcium complexing properties. The composition of obtained active fractions was analyzed by GC/MS and NMR methods. The influence of preparations on inhibition of formation and dissolution of model and real kidney stones were evaluated based on conductrometric titration, flame photometry and microscopic analysis. The "fraction soluble in methanol" obtained from water-alkaline extracts contains sugar alcohols and organic acids, and is effective in dissolving the kidney stones. The "fraction insoluble in methanol" contains only sugar derivatives and it changes the morphology of the crystals, making them "jelly-like". Both fractions are potentially effective in kidney stone therapy.

  19. Chemical analysis of the formation of calcium carbonate and its influence on calcium hydroxide pastes in connective tissue of the dog--Part II.

    PubMed

    Estrela, C; Pesce, H F

    1997-01-01

    The objective of this research was to chemically analyze calcium hydroxide pastes added to three hydrosoluble vehicles having different acid-base characteristics by implanting polyethylene tubes in subcutaneous connective tissue in dogs, evaluating the formation of calcium carbonate over a period of 7, 30, 45, and 60 days. The three vehicles were saline, anesthetic, and polyethylene glycol 400. Determination of the formation of calcium carbonate was evaluated by volumetry of neutralization using hydrochloric acid for titration. PMID:9485637

  20. Effects of calcium carbonate particulate releasing surgical anchors on bone and tendon healing

    E-print Network

    Medeiros, Jordan-Ryan J. I. K

    2007-01-01

    The Calaxo ® screw, developed by Smith and Nephew, is a novel biomedical composite composed of poly-DL-lactide-co-glycolide (PLLA:PGA) 85:15 and calcium carbonate particulates. Comparisons to an identical surgical anchor ...

  1. Calcium carbonate corrosivity in an Alaskan inland sea

    NASA Astrophysics Data System (ADS)

    Evans, W.; Mathis, J. T.; Cross, J. N.

    2014-01-01

    Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (?) to levels that are corrosive (i.e., ? ? 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacial melt. Carbonate system data collected in May and September from 2009 through 2012 in Prince William Sound (PWS), a semienclosed inland sea located on the south-central coast of Alaska and ringed with fjords containing tidewater glaciers, reveal the unique impact of glacial melt on CaCO3 corrosivity. Initial limited sampling was expanded in September 2011 to span large portions of the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (< 50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive ? levels seen below the mixed layer over a portion of the sound, and (2) as point sources for surface plumes of glacial melt with corrosive ? levels (? for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. CaCO3 corrosivity in glacial melt plumes is poorly reflected by pCO2 or pHT, indicating that either one of these carbonate parameters alone would fail to track ? in PWS. The unique ? and pCO2 conditions in the glacial melt plumes enhances atmospheric CO2 uptake, which, if not offset by mixing or primary productivity, would rapidly exacerbate CaCO3 corrosivity in a positive feedback. The cumulative effects of glacial melt and air-sea gas exchange are likely responsible for the seasonal reduction of ? in PWS, making PWS highly sensitive to increasing atmospheric CO2 and amplified CaCO3 corrosivity.

  2. Calcium carbonate corrosivity in an Alaskan inland sea

    NASA Astrophysics Data System (ADS)

    Evans, W.; Mathis, J. T.; Cross, J. N.

    2013-09-01

    Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (?) to levels that are corrosive (i.e. ? ? 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacial melt. Carbonate system data collected in May and September from 2009 through 2012 in Prince William Sound (PWS), a semi-enclosed inland sea located on the south-central coast of Alaska that is ringed with fjords containing tidewater glaciers, reveal the unique impact of glacial melt on CaCO3 corrosivity. Initial limited sampling was expanded in September 2011 to span large portions of the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (<50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive ? levels seen below the mixed layer across the sound, and (2) as point sources for surface plumes of glacial melt with corrosive ? levels (? for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. CaCO3 corrosivity in glacial melt plumes is poorly reflected by pCO2 or pHT, indicating that either one of these carbonate parameters alone would fail to track ? in PWS. The unique ? and pCO2 conditions in the glacial melt plumes enhances atmospheric CO2 uptake, which, if not offset by mixing or primary productivity, would rapidly exacerbate CaCO3 corrosivity in a positive feedback. The cumulative effects of glacial melt and air-sea gas exchange are likely responsible for the seasonal widespread reduction of ? in PWS; making PWS highly sensitive to increasing atmospheric CO2 and amplified CaCO3 corrosivity.

  3. Crystal chemistry and structure refinement of five hydrated calcium borates

    USGS Publications Warehouse

    Clark, J.R.; Appleman, D.E.; Christ, C.L.

    1964-01-01

    The crystal structures of the five known members of the series Ca2B6O11??xH2O (x = 1, 5, 5, 7, 9, and 13) have been refined by full-matrix least-squares techniques, yielding bond distances and angles with standard errors of less than 0??01 A?? and 0??5??, respectively. The results illustrate the crystal chemical principles that govern the structures of hydrated borate compounds. The importance of hydrogen bonding in the ferroelectric transition of colemanite is confirmed by more accurate proton assignments. ?? 1964.

  4. An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

    Microsoft Academic Search

    Yingkai Xiao; Shizhen Li; Haizhen Wei; Aide Sun; Weijian Zhou; Weiguo Liu

    2006-01-01

    Inorganic calcium carbonate precipitation from natural seawater and saline water at various pH values was carried out experimentally.\\u000a The results show the clear positive relationships between boron concentration and ?11B of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic\\u000a fractionation between inorganic calcite and seawater\\/saline water with pH are inconsistent

  5. Degradation of poly(ethylene- co-methacrylic acid)–calcium carbonate nanocomposites

    Microsoft Academic Search

    R. H. Krämer; M. A. Raza; U. W. Gedde

    2007-01-01

    Composites of poly(ethylene-co-methacrylic acid) with 5 mass fraction percent of precipitated calcium carbonate nanoparticles were prepared by melt extrusion on a miniature melt-blender and medium-scale production equipment. The composites consisted mostly of isolated particles. The ultimate mechanical properties of the nanocomposites were consequently largely superior to composites with micron-sized filler. The calcium carbonate particles were shown to offer a large

  6. Carbonated calcium phosphates are suitable pH-stabilising fillers for biodegradable polyesters

    Microsoft Academic Search

    Carsten Schiller; Matthias Epple

    2003-01-01

    Carbonated amorphous calcium phosphates were prepared with different carbonate content. Their ability to neutralise acidity was probed by time-resolved titration experiments with lactic acid, the monomer that results from degradation of polylactide. The results show that although calcium phosphate as such can reduce acidity, their buffering range lies at a pH of about 4, i.e. outside the physiological range. This

  7. Preparation and mechanism of calcium phosphate coatings on chemical modified carbon fibers by biomineralization

    Microsoft Academic Search

    Su-ping HUANG; Ke-chao ZHOU; Zhi-you LI

    2008-01-01

    In order to prepare HA coatings on the carbon fibers, chemical modification and biomineralization processes were applied. The phase components, morphologies, and possible growth mechanism of calcium phosphate were studied by infrared spectroscopy(IR), X-ray diffractometry(XRD) and scanning electron microscopy(SEM). The results show that calcium phosphate coating on carbon fibers can be obtained by biomineralization. But the phase components and morphologies

  8. Facile preparation of calcium carbonate particles with unusual morphologies by precipitation reaction

    Microsoft Academic Search

    Jiaguo Yu; Ming Lei; Bei Cheng; Xiujian Zhao

    2004-01-01

    Calcium carbonate particles with different morphologies were prepared by the reaction of sodium carbonate with calcium chloride in the presence of different organic additives at 25°C and 80°C. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The results showed that both organic additives and temperature turned out to be important parameters for the control of morphologies

  9. Facile preparation of monodispersed calcium carbonate spherical particles via a simple precipitation reaction

    Microsoft Academic Search

    Jiaguo Yu; Ming Lei; Bei Cheng

    2004-01-01

    Monodispersed calcium carbonate spherical particles with a size of about 1–2?m could be prepared by a precipitation reaction of sodium carbonate with calcium chloride in the presence of polymaleicanhydride (PMA) or poly (sodium 4-styene-sulfonate) (PSSS) at room temperature. The as-prepared products were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry–thermogravimetry (DSC–TG). It was found that

  10. Powder XRD and dielectric studies of gel grown calcium pyrophosphate crystals

    NASA Astrophysics Data System (ADS)

    Parekh, Bharat; Parikh, Ketan; Joshi, Mihir

    2013-06-01

    Formation of calcium pyrophosphate dihydrate (CPPD) crystals in soft tissues such as cartilage, meniscus and synovial tissue leads to CPPD deposition diseases. The appearance of these crystals in the synovial fluid can give rise to an acute arthritic attack with pain and inflammation of the joints, a condition called pseudo-gout. The growth of CPP crystals has been carried out, in the present study, using the single diffusion gel growth technique, which can broadly mimic in vitro the condition in soft tissues. The crystals were characterized by different techniques. The FTIR study revealed the presence of various functional groups. Powder XRD study was also carried out to verify the crystal structure. The dielectric study was carried out at room temperature by applying field of different frequency from 500 Hz to 1 MHz. The dielectric constant, dielectric loss and a.c. resistivity decreased as frequency increased, whereas the a.c. conductivity increased as frequency increased.

  11. Calcium carbonate nucleation driven by ion binding in a biomimetic matrix revealed by in situ electron microscopy

    NASA Astrophysics Data System (ADS)

    Smeets, Paul J. M.; Cho, Kang Rae; Kempen, Ralph G. E.; Sommerdijk, Nico A. J. M.; de Yoreo, James J.

    2015-04-01

    The characteristic shapes, structures and properties of biominerals arise from their interplay with a macromolecular matrix. The developing mineral interacts with acidic macromolecules, which are either dissolved in the crystallization medium or associated with insoluble matrix polymers, that affect growth habits and phase selection or completely inhibit precipitation in solution. Yet little is known about the role of matrix-immobilized acidic macromolecules in directing mineralization. Here, by using in situ liquid-phase electron microscopy to visualize the nucleation and growth of CaCO3 in a matrix of polystyrene sulphonate (PSS), we show that the binding of calcium ions to form Ca–PSS globules is a key step in the formation of metastable amorphous calcium carbonate (ACC), an important precursor phase in many biomineralization systems. Our findings demonstrate that ion binding can play a significant role in directing nucleation, independently of any control over the free-energy barrier to nucleation.

  12. Calcium carbonate nucleation driven by ion binding in a biomimetic matrix revealed by in situ electron microscopy.

    PubMed

    Smeets, Paul J M; Cho, Kang Rae; Kempen, Ralph G E; Sommerdijk, Nico A J M; De Yoreo, James J

    2015-04-01

    The characteristic shapes, structures and properties of biominerals arise from their interplay with a macromolecular matrix. The developing mineral interacts with acidic macromolecules, which are either dissolved in the crystallization medium or associated with insoluble matrix polymers, that affect growth habits and phase selection or completely inhibit precipitation in solution. Yet little is known about the role of matrix-immobilized acidic macromolecules in directing mineralization. Here, by using in situ liquid-phase electron microscopy to visualize the nucleation and growth of CaCO3 in a matrix of polystyrene sulphonate (PSS), we show that the binding of calcium ions to form Ca-PSS globules is a key step in the formation of metastable amorphous calcium carbonate (ACC), an important precursor phase in many biomineralization systems. Our findings demonstrate that ion binding can play a significant role in directing nucleation, independently of any control over the free-energy barrier to nucleation. PMID:25622001

  13. Evolution of the calcium hydroxyapatite crystal structure under plasma deposition and subsequent reducing treatment

    NASA Astrophysics Data System (ADS)

    Shamrai, V. F.; Karpikhin, A. E.; Sirotinkin, V. P.; Kalita, V. I.; Komlev, D. I.

    2014-03-01

    The structure of hydroxyapatite plasma coatings on a titanium substrate has been investigated by the X-ray Rietveld method. The hydroxyapatite crystal structure in plasma-deposited samples is characterized by strong distortions of its main element (tetrahedral PO4 cluster) and coordination calcium polyhedra, as well as calcium deficit in the Ca2 site; however, these features do not change the main motif of the hydroxyapatite structure. The bond distortions in PO4 clusters are estimated by the Bauer method. It is shown that hydrothermal treatment leads to the almost complete recovery of the hydroxyapatite structure.

  14. Preparation, crystal structure and photoluminescence of garnet-type calcium tin titanium aluminates

    SciTech Connect

    Yamane, Hisanori, E-mail: yamane@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kawano, Tetsuya [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2011-05-15

    Colorless and transparent single crystals of Ca{sub 3}Sn{sub 2.2}Ti{sub 0.8}Al{sub 2}O{sub 12}, which emit blue-white light under ultraviolet light, were prepared by heating a mixture of oxides and calcium carbonate with a calcium and aluminum-rich composition at 1500 {sup o}C. Single crystal X-ray diffraction revealed that the crystal structure is the garnet-type with a cubic cell parameter (a=12.5309(3) A) and the space group, Ia 3-bar d (R1=0.0277, wR2=0.0663, and S=1.367 for all data). The structural formula is presented as Ca{sub 3}[Sn{sub 0.96}Ti{sub 0.04}]{sub octa}[Al{sub 0.67}Ti{sub 0.24}Sn{sub 0.09}]{sub tetra}O{sub 12}. Polycrystalline solid solutions of Ca{sub 3}Sn{sub 3-x}Ti{sub x}Al{sub 2}O{sub 12} were prepared by solid state reaction in air at 1370 {sup o}C with nominal titanium contents from x=0.6 to 1.4. The refined unit cell parameter decreased with increasing x. A broad blue-white emission with a peak wavelength of 465 nm was observed for the solid solutions at room temperature. -- Graphical abstract: Garnet-type solid solutions of Ca{sub 3}Sn{sub 3-x}Ti{sub x}Al{sub 2}O{sub 12} (x=0.6-1.4) were prepared. Sn{sup 4+} and Ti{sup 4+} partially occupy both tetrahedral and octahedral sites. The solid solutions showed a broad emission band peaking at 465 nm under UV excitation. Display Omitted Research highlights: {yields} New garnet-type solid solutions were found in the CaO-Al{sub 2}O{sub 3}-TiO{sub 2}-SnO{sub 2} system. {yields} Single crystals of Ca{sub 3}Sn{sub 2.2}Ti{sub 0.8}Al{sub 2}O{sub 12} were obtained by the self-flux method. {yields} Solid solutions with nominal compositions Ca{sub 3}Sn{sub 3-x}Ti{sub x}Al{sub 2}O{sub 12} (x=0.6-1.4) were prepared by solid state reaction at 1370 {sup o}C. {yields} Sn{sup 4+} and Ti{sup 4+} partially occupy both tetrahedral and octahedral sites, respectively, in the garnet-type structure. {yields} Ca{sub 3}Sn{sub 3-x}Ti{sub x}Al{sub 2}O{sub 12} solid solutions emitted blue-white light with a peak wavelength at 465 nm under UV irradiation.

  15. Histological Observations of the Adhesion and Endocytosis of Calcium Oxalate Crystals in MDCK Cells and in Rat and Human Kidney

    Microsoft Academic Search

    Shoichi Ebisuno; Yasuo Kohjimoto; Miyako Tamura; Takeshi Inagaki; Tadashi Ohkawa

    1997-01-01

    Adhesion and\\/or endocytosis of calcium oxalate crystals to the three kinds of tubular cells (Madin-Darby canine kidney (MDCK) cells, rat and human kidney) were demonstrated morphologically to presume the initial formation of kidney stone. After removal of the nonadhesion crystals, the cells were subsequently recultured in the vertical position. At various times thereafter, the interactions between COM crystals and MDCK

  16. SURVEY OF NUMBER AND ARRANGEMENT OF CALCIUM OXALATE CRYSTALS IN LEAVES OF ANNUAL AND PERENNIAL SOYBEAN AND ALLIED TAXA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean is only one of many flowering plants that contain calcium oxalate crystals in its plant organs, especially in the leaves. Even though the functional significance of the crystals is still not understood, the sometimes massive amount, location and structure of crystals have been used in syste...

  17. Effects of phosphate pollutants on the growth of the oyster Crassostrea virginica in the Pamlico River estuary and on calcium carbonate crystallization in vitro. Part 2. Extension. Period of project: September 1, 1984-February 28, 1985

    SciTech Connect

    Wilbur, K.M.

    1986-01-01

    Four phosphates at various concentrations were studied for effect on shell growth of the clam Rangia cuneata over 24 h and 36 h using /sup 45/Ca. Four phosphates, present in polluted waters, have been examined for their effects at various concentrations on crystallization rate of CaCO/sub 3/ in vitro. Growth of the clam in the Pamlico River, North Carolina, were followed during fall, winter, and spring along with records of phosphate, temperature, salinity, chlorophyll and dissolved oxygen of the native water. 2 figs., 2 tabs.

  18. GFP Facilitates Native Purification of Recombinant Perlucin Derivatives and Delays the Precipitation of Calcium Carbonate

    PubMed Central

    Weber, Eva; Guth, Christina; Weiss, Ingrid M.

    2012-01-01

    Insolubility is one of the possible functions of proteins involved in biomineralization, which often limits their native purification. This becomes a major problem especially when recombinant expression systems are required to obtain larger amounts. For example, the mollusc shell provides a rich source of unconventional proteins, which can interfere in manifold ways with different mineral phases and interfaces. Therefore, the relevance of such proteins for biotechnological processes is still in its infancy. Here we report a simple and reproducible purification procedure for a GFP-tagged lectin involved in biomineralization, originally isolated from mother-of-pearl in abalone shells. An optimization of E. coli host cell culture conditions was the key to obtain reasonable yields and high degrees of purity by using simple one-step affinity chromatography. We identified a dual functional role for the GFP domain when it became part of a mineralizing system in vitro. First, the GFP domain improved the solubility of an otherwise insoluble protein, in this case recombinant perlucin derivatives. Second, GFP inhibited calcium carbonate precipitation in a concentration dependent manner. This was demonstrated here using a simple bulk assay over a time period of 400 seconds. At concentrations of 2 µg/ml and higher, the inhibitory effect was observed predominantly for HCO3? as the first ionic interaction partner, but not necessarily for Ca2+. The interference of GFP-tagged perlucin derivatives with the precipitation of calcium carbonate generated different types of GFP-fluorescent composite calcite crystals. GFP-tagging offers therefore a genetically tunable tool to gently modify mechanical and optical properties of synthetic biocomposite minerals. PMID:23056388

  19. Designed three-dimensional freestanding single-crystal carbon architectures.

    PubMed

    Park, Ji-Hoon; Cho, Dae-Hyun; Moon, Youngkwon; Shin, Ha-Chul; Ahn, Sung-Joon; Kwak, Sang Kyu; Shin, Hyeon-Jin; Lee, Changgu; Ahn, Joung Real

    2014-11-25

    Single-crystal carbon nanomaterials have led to great advances in nanotechnology. The first single-crystal carbon nanomaterial, fullerene, was fabricated in a zero-dimensional form. One-dimensional carbon nanotubes and two-dimensional graphene have since followed and continue to provide further impetus to this field. In this study, we fabricated designed three-dimensional (3D) single-crystal carbon architectures by using silicon carbide templates. For this method, a designed 3D SiC structure was transformed into a 3D freestanding single-crystal carbon structure that retained the original SiC structure by performing a simple single-step thermal process. The SiC structure inside the 3D carbon structure is self-etched, which results in a 3D freestanding carbon structure. The 3D carbon structure is a single crystal with the same hexagonal close-packed structure as graphene. The size of the carbon structures can be controlled from the nanoscale to the microscale, and arrays of these structures can be scaled up to the wafer scale. The 3D freestanding carbon structures were found to be mechanically stable even after repeated loading. The relationship between the reversible mechanical deformation of a carbon structure and its electrical conductance was also investigated. Our method of fabricating designed 3D freestanding single-crystal graphene architectures opens up prospects in the field of single-crystal carbon nanomaterials and paves the way for the development of 3D single-crystal carbon devices. PMID:25329767

  20. Effect of calcium carbonate on the compliance of an apatitic calcium phosphate bone cement

    Microsoft Academic Search

    I. Khairoun; M. G. Boltong; F. C. M. Driessens; J. A. Planell

    1997-01-01

    Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing ?-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to

  1. Particle Size Determination of (Functionalized) Colloidal Calcium Carbonate by Small Angle X-Ray Scattering—Relation with Antiwear Properties

    Microsoft Academic Search

    Bruno Delfort; Bertrand Daoudal; Loïc Barré

    1999-01-01

    Three different colloidal calcium carbonate additives were each functionalized with dithiodiglycolic acid in order to convert 10 percent of the calcium carbonate content into the appropriate calcium carboxylate salt. The generated sulfurized calcium salts are located inside the micellar cores.Investigation of colloidal size distribution using small-angle-X-ray scattering has shown that the reaction takes place inside each micelle without modification of

  2. Specific adsorption of osteopontin and synthetic polypeptides to calcium oxalate monohydrate crystals.

    PubMed

    Taller, Adam; Grohe, Bernd; Rogers, Kem A; Goldberg, Harvey A; Hunter, Graeme K

    2007-09-01

    Protein-crystal interactions are known to be important in biomineralization. To study the physicochemical basis of such interactions, we have developed a technique that combines confocal microscopy of crystals with fluorescence imaging of proteins. In this study, osteopontin (OPN), a protein abundant in urine, was labeled with the fluorescent dye AlexaFluor-488 and added to crystals of calcium oxalate monohydrate (COM), the major constituent of kidney stones. In five to seven optical sections along the z axis, scanning confocal microscopy was used to visualize COM crystals and fluorescence imaging to map OPN adsorbed to the crystals. To quantify the relative adsorption to different crystal faces, fluorescence intensity was measured around the perimeter of the crystal in several sections. Using this method, it was shown that OPN adsorbs with high specificity to the edges between {100} and {121} faces of COM and much less so to {100}, {121}, or {010} faces. By contrast, poly-L-aspartic acid adsorbs preferentially to {121} faces, whereas poly-L-glutamic acid adsorbs to all faces approximately equally. Growth of COM in the presence of rat bone OPN results in dumbbell-shaped crystals. We hypothesize that the edge-specific adsorption of OPN may be responsible for the dumbbell morphology of COM crystals found in human urine. PMID:17496021

  3. Origin and significance of calcium carbonate in soils of southwestern Patagonia

    Microsoft Academic Search

    James G. Bockheim; Daniel C. Douglass

    2006-01-01

    A soil chronosequence spanning the last 0.76–1.0 Ma shows a progressive increase in calcium carbonates based on (1) thickness of the Bk+BCk horizons, (2) maximum carbonate stage, (3) profile accumulation of pedogenic carbonates, and (4) mass flux of Ca from a geochemical mass balance. We favor a dust origin of the carbonates because (1) the till parent materials contain low amounts

  4. Induced orientational behavior of liquid crystal polymer by carbon fibers

    NASA Technical Reports Server (NTRS)

    Chung, T. S.; Gurion, Z.; Stamatoff, J. B.

    1985-01-01

    Experimental results are presented that show that the structure of carbon fibers induces molecular orientation of liquid crystal polymers. X-ray diffraction data are used to demonstrate final collinearity of the polymer molecular axis and carbon fiber axis independent of fabrication approaches or prefabrication orientation of the polymer relative to the carbon fiber direction. The final degree of polymer molecular orientation approximately equals the degree of carbon basal plane orientation within the carbon fiber.

  5. Intracrystalline Proteins Promote Dissolution of Urinary Calcium Oxalate Crystals in Cultured Renal Epithelial Cells

    NASA Astrophysics Data System (ADS)

    Grover, Phulwinder K.; Thurgood, Lauren A.; Fleming, David E.; van Bronswijk, Wilhelm; Ryall, Rosemary L.

    2007-04-01

    We have proposed that internalized calcium oxalate (CaOx) crystals containing intracrystalline proteins would be vulnerable to intracellular dissolution. The aims of this study were (1) to measure non-uniform strain and crystallite size in CaOx monohydrate (COM) crystals containing increasing amounts of intracrystalline crystal matrix extract (CME) and (2) to compare the rates of crystal dissolution in Madin-Darby canine kidney (MDCKII) cells. CME was isolated by demineralization of COM crystals generated from human urine. Cold and 14C-oxalate-labelled COM crystals were precipitated from ultrafiltered urine containing CME at final concentrations of 0-5mg/L. Non-uniform strain and crystallite size were determined using synchrotron X-ray diffraction with Rietveld whole-pattern peak fitting and profile analysis, and the protein content of the crystals was analyzed using SDS-PAGE and Western blotting for prothrombin fragment 1. Radiolabeled crystals were added to MDCKII cells and dissolution was expressed as radioactive label released into the medium relative to that in the crystals at zero time. Non-uniform strain increased and crystallite size decreased proportionally with rising CME concentration, reaching saturation between approximately 1 and 5 mg/L, and demonstrating unequivocally the inclusion of increasing quantities of proteins in the crystals. This was confirmed by SDS-PAGE and Western blotting. Crystal dissolution also followed saturation kinetics. These findings were confirmed by field emission scanning electron microscopy (FESEM), which showed that the degree of crystal degradation increased relative to CME concentration. We conclude that intracrystalline proteins enhance intracellular dissolution of CaOx crystals and thus may provide a natural defense against stone pathogenesis.

  6. Efficacy, Tolerability, and Safety of Lanthanum Carbonate in Hyperphosphatemia: A 6Month, Randomized, Comparative Trial versus Calcium Carbonate

    Microsoft Academic Search

    A. J. Hutchison; B. Maes; J. Vanwalleghem; G. Asmus; E. Mohamed; R. Schmieder; W. Backs; R. Jamar; A. Vosskühler

    2005-01-01

    Background\\/Aims: Hyperphosphatemia is an important clinical consequence of renal failure, and its multiple adverse systemic effects are associated with significantly increased risks of morbidity and mortality in dialysis patients. Existing oral phosphate binders have not permitted control of serum phosphate within currently accepted guidelines. This study compares lanthanum carbonate with calcium carbonate for control of serum phosphate in hemodialysis patients.

  7. Liquid crystal polyester-carbon fiber composites

    NASA Technical Reports Server (NTRS)

    Chung, T. S.

    1984-01-01

    Liquid crystal polymers (LCP) have been developed as a thermoplastic matrix for high performance composites. A successful melt impregnation method has been developed which results in the production of continuous carbon fiber (CF) reinforced LCP prepreg tape. Subsequent layup and molding of prepreg into laminates has yielded composites of good quality. Tensile and flexural properties of LCP/CF composites are comparable to those of epoxy/CF composites. The LCP/CF composites have better impact resistance than the latter, although epoxy/CF composites possess superior compression and shear strength. The LCP/CF composites have good property retention until 200 F (67 % of room temperature value). Above 200 F, mechanical properties decrease significantly. Experimental results indicate that the poor compression and shear strength may be due to the poor interfacial adhesion between the matrix and carbon fiber as adequate toughness of the LCP matrix. Low mechanical property retention at high temperatures may be attributable to the low beta-transition temperature (around 80 C) of the LCP matrix material.

  8. 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. PMID:24674384

  9. Oxygen spectroscopy and polarization-dependent imaging contrast (PIC)-mapping of calcium carbonate minerals and biominerals.

    PubMed

    DeVol, Ross T; Metzler, Rebecca A; Kabalah-Amitai, Lee; Pokroy, Boaz; Politi, Yael; Gal, Assaf; Addadi, Lia; Weiner, Steve; Fernandez-Martinez, Alejandro; Demichelis, Raffaella; Gale, Julian D; Ihli, Johannes; Meldrum, Fiona C; Blonsky, Adam Z; Killian, Christopher E; Salling, C B; Young, Anthony T; Marcus, Matthew A; Scholl, Andreas; Doran, Andrew; Jenkins, Catherine; Bechtel, Hans A; Gilbert, Pupa U P A

    2014-07-17

    X-ray absorption near-edge structure (XANES) spectroscopy and spectromicroscopy have been extensively used to characterize biominerals. Using either Ca or C spectra, unique information has been obtained regarding amorphous biominerals and nanocrystal orientations. Building on these results, we demonstrate that recording XANES spectra of calcium carbonate at the oxygen K-edge enables polarization-dependent imaging contrast (PIC) mapping with unprecedented contrast, signal-to-noise ratio, and magnification. O and Ca spectra are presented for six calcium carbonate minerals: aragonite, calcite, vaterite, monohydrocalcite, and both hydrated and anhydrous amorphous calcium carbonate. The crystalline minerals reveal excellent agreement of the extent and direction of polarization dependences in simulated and experimental XANES spectra due to X-ray linear dichroism. This effect is particularly strong for aragonite, calcite, and vaterite. In natural biominerals, oxygen PIC-mapping generated high-magnification maps of unprecedented clarity from nacre and prismatic structures and their interface in Mytilus californianus shells. These maps revealed blocky aragonite crystals at the nacre-prismatic boundary and the narrowest calcite needle-prisms. In the tunic spicules of Herdmania momus, O PIC-mapping revealed the size and arrangement of some of the largest vaterite single crystals known. O spectroscopy therefore enables the simultaneous measurement of chemical and orientational information in CaCO3 biominerals and is thus a powerful means for analyzing these and other complex materials. As described here, PIC-mapping and spectroscopy at the O K-edge are methods for gathering valuable data that can be carried out using spectromicroscopy beamlines at most synchrotrons without the expense of additional equipment. PMID:24821199

  10. Identification of proteins extracted from calcium oxalate and calcium phosphate crystals induced in the urine of healthy and stone forming subjects

    Microsoft Academic Search

    Fouad Atmani; Patricia A. Glenton; Saeed R. Khan

    1998-01-01

    The purpose of our study was to identify the proteins and investigate the differences, if any, between protein components\\u000a of the matrices of calcium oxalate (CaOx) and calcium phosphate (CaP) crystals induced in?vitro in whole human urine of healthy\\u000a individuals and kidney stone patients. In addition, preliminary studies were performed to understand the effect of centrifugation\\u000a and filtration of urine

  11. Journal of Crystal Growth ] (

    E-print Network

    by hydrothermal carbonation of calcium hydroxide G. Montes-Hernandeza,Ã, A. Ferna´ ndez-Marti´neza,b , L. Charleta 2008 Communicated by S. Veesler Abstract The hydrothermal carbonation of calcium hydroxide (Ca(OH)2 and surface area of the synthesized calcite crystals. The present study is focused on the estimation

  12. Exotic behavior and crystal structures of calcium under pressure

    PubMed Central

    Oganov, Artem R.; Ma, Yanming; Xu, Ying; Errea, Ion; Bergara, Aitor; Lyakhov, Andriy O.

    2010-01-01

    Experimental studies established that calcium undergoes several counterintuitive transitions under pressure: fcc ? bcc ? simple cubic ? Ca-IV ? Ca-V, and becomes a good superconductor in the simple cubic and higher-pressure phases. Here, using ab initio evolutionary simulations, we explore the behavior of Ca under pressure and find a number of new phases. Our structural sequence differs from the traditional picture for Ca, but is similar to that for Sr. The ?-tin (I41/amd) structure, rather than simple cubic, is predicted to be the theoretical ground state at 0 K and 33–71 GPa. This structure can be represented as a large distortion of the simple cubic structure, just as the higher-pressure phases stable between 71 and 134 GPa. The structure of Ca-V, stable above 134 GPa, is a complex host-guest structure. According to our calculations, the predicted phases are superconductors with Tc increasing under pressure and reaching approximately 20 K at 120 GPa, in good agreement with experiment. PMID:20382865

  13. Improved calcium sulfate recovery from a reverse osmosis retentate using eutectic freeze crystallization.

    PubMed

    Randall, D G; Mohamed, R; Nathoo, J; Rossenrode, H; Lewis, A E

    2013-01-01

    A novel low temperature crystallization process called eutectic freeze crystallization (EFC) can produce both salt(s) and ice from a reverse osmosis (RO) stream by operating at the eutectic temperature of a solution. The EFC reject stream, which is de-supersaturated with respect to the scaling component, can subsequently be recycled back to the RO process for increased water recovery. This paper looks at the feasibility of using EFC to remove calcium sulfate from an RO retentate stream and compares the results to recovery rates at 0 and 20 °C. The results showed that there was a greater yield of calcium sulfate obtained at 0 °C as compared with 20 °C. Operation under eutectic conditions, with only a 20% ice recovery, resulted in an even greater yield of calcium sulfate (48%) when compared with yields obtained at operating temperatures of 0 and 20 °C (15% at 0 °C and 13% at 20 °C). The theoretical calcium recoveries were found to be 75 and 70% at 0 and 20 °C respectively which was higher than the experimentally determined values. The EFC process has the added advantage of producing water along with a salt. PMID:23128631

  14. A simple method for quantitating the propensity for calcium oxalate crystallization in urine

    NASA Technical Reports Server (NTRS)

    Wabner, C. L.; Pak, C. Y.

    1991-01-01

    To assess the propensity for spontaneous crystallization of calcium oxalate in urine, the permissible increment in oxalate is calculated. The previous method required visual observation of crystallization with the addition of oxalate, this warranted the need for a large volume of urine and a sacrifice in accuracy in defining differences between small incremental changes of added oxalate. Therefore, this method has been miniaturized and spontaneous crystallization is detected from the depletion of radioactive oxalate. The new "micro" method demonstrated a marked decrease (p < 0.001) in the permissible increment in oxalate in urine of stone formers versus normal subjects. Moreover, crystallization inhibitors added to urine, in vitro (heparin or diphosphonate) or in vivo (potassium citrate administration), substantially increased the permissible increment in oxalate. Thus, the "micro" method has proven reliable and accurate in discriminating stone forming from control urine and in distinguishing changes of inhibitory activity.

  15. Polyhydroxycarboxylic acids as inhibitors of calcium oxalate crystal growth; Relation between inhibitory capacity and chemical structure

    NASA Astrophysics Data System (ADS)

    Grases, F.; Millan, A.; Garcia-Raso, A.

    1988-07-01

    The kinetics of crystal growth of calcium oxalate monohydrate seed crystals were investigated potentiometrically in the presence of several polyhydroxycarboxylic acids; etylenediaminetetraacetic acid, citric acid, isocitric acid, malic acid and succinic acid, and it was found that they inhibited crystal growth, except in the case of isocitric acid manifested no-effects. An apparent rate order of 2 in the presence of all the inhibitors, suggested a spiral growth mechanism. Application to a kinetic Langmuir-type model suggested that adsorption of the polyhydroxycarboxylic acids, at the active growth sites, is the cause of the reduction in the crystal growth rates. The inhibitory action of the different substances assayed was comparatively evaluated. Relations between chemical structure and inhibitory capacity were established.

  16. Monodisperse Calcium Carbonate Microtablets Forming at 701C in Prerefrigerated CaCl2GelatinUrea Solutions

    E-print Network

    Tas, A. Cuneyt

    Ceramic Society #12;Using dissolved sodium carbonate (either Na2CO3 or NaHCO3) as the CO3 2� sourceMonodisperse Calcium Carbonate Microtablets Forming at 701C in Prerefrigerated CaCl2­Gelatin Calcium carbonate particles with a unique tablet shape were produced by simply aging the prerefrigerated

  17. Isolation of a crystal matrix protein associated with calcium oxalate precipitation in vacuoles of specialized cells.

    PubMed

    Li, Xingxiang; Zhang, Dianzhong; Lynch-Holm, Valerie J; Okita, Thomas W; Franceschi, Vincent R

    2003-10-01

    The formation of calcium (Ca) oxalate crystals is considered to be a high-capacity mechanism for regulating Ca in many plants. Ca oxalate precipitation is not a stochastic process, suggesting the involvement of specific biochemical and cellular mechanisms. Microautoradiography of water lettuce (Pistia stratiotes) tissue exposed to 3H-glutamate showed incorporation into developing crystals, indicating potential acidic proteins associated with the crystals. Dissolution of crystals leaves behind a crystal-shaped matrix "ghost" that is capable of precipitation of Ca oxalate in the original crystal morphology. To assess whether this matrix has a protein component, purified crystals were isolated and analyzed for internal protein. Polyacrylamide gel electrophoresis revealed the presence of one major polypeptide of about 55 kD and two minor species of 60 and 63 kD. Amino acid analysis indicates the matrix protein is relatively high in acidic amino acids, a feature consistent with its solubility in formic acid but not at neutral pH. 45Ca-binding assays demonstrated the matrix protein has a strong affinity for Ca. Immunocytochemical localization using antibody raised to the isolated protein showed that the matrix protein is specific to crystal-forming cells. Within the vacuole, the surface and internal structures of two morphologically distinct Ca oxalate crystals, raphide and druse, were labeled by the antimatrix protein serum, as were the surfaces of isolated crystals. These results demonstrate that a specific Ca-binding protein exists as an integral component of Ca oxalate crystals, which holds important implications with respect to regulation of crystal formation. PMID:14555781

  18. Inhibition and dissolution of calcium oxalate crystals by Berberis Vulgaris-Q and other metabolites

    NASA Astrophysics Data System (ADS)

    Das, Ishwar; Gupta, S. K.; Pandey, V. N.; Ansari, Shoeb A.

    2004-07-01

    Inhibition and dissolution of calcium oxalate crystals in solutions containing a homoeopathic medicine Berberis Vulgaris-Q, amino acids such as aspartic acid, glutamic acid, ?-keto glutaric acid, a naturally occurring inhibitor and juices of some fruits of citrus group such as lemon, orange and mausammi have been studied. Considerable solubility was observed and found that in each case solubility changes with time or concentration periodically. Chelation may be one of the reasons for inhibition.

  19. Diphosphonates Inhibit Formation of Calcium Phosphate Crystals in vitro and Pathological Calcification in vivo

    Microsoft Academic Search

    Marion D. Francis; R. Graham G. Russell; Herbert Fleisch

    1969-01-01

    Two diphosphonates containing the P-C-P bond, CH3C(OH)(PO3HNa)2 and H2C(PO3HNa)2, inhibit the crystallization of calcium phosphate in vitro and prevent aortic calcification of rats given large amounts of vitamin D3. The diphosphonates therefore have effects similar to those described for compounds containing the P-O-P bond but are active when administered orally.

  20. Electronic structure and bonding in calcium apatite crystals: Hydroxyapatite, fluorapatite, chlorapatite, and bromapatite

    Microsoft Academic Search

    Paul Rulis; Lizhi Ouyang; W. Y. Ching

    2004-01-01

    We present a detailed analysis of the electronic structure, bonding, charge transfer, and optical properties of selected perfect-crystal calcium apatites [ Ca10(PO4)6X2 with X=(OH)-,F-,Cl- , or Br- ]. The ab initio orthogonalized linear combinations of atomic orbitals-density-functional-theory-based computational method is used to obtain the band structure, total and partial density of states, bond order, Mulliken effective charge, dielectric constant, and

  1. ESR studies of X-irradiated strontium mixed calcium tartrate crystals

    Microsoft Academic Search

    K. Suryanarayana; S. M Dharmaprakash; A. Ananda

    2000-01-01

    The electron spin resonance spectra of X-ray irradiated single crystals of strontium doped calcium tartrate tetrahydrate (CST) with molecular formula Ca0.88Sr0.12C4H4O6·4H2O grown in gels has been investigated. Only one species of free radical but with two magnetically unequivalent sites was observed at room temperature. The free radical was found to be the result of the splitting of a C–H bond

  2. Characterization of uronic-acid-rich inhibitor of calcium oxalate crystallization isolated from rat urine

    Microsoft Academic Search

    F. Atmani; S. R. Khan

    1995-01-01

    Human urine contains several macromolecules which inhibit calcium oxalate crystallization. Uronic-acid-rich protein (UAP), a glycoprotein with a molecular weight of approximately 35 kDa, is one such inhibitor. Here we report the characterization of UAP extracted from rat urine using three chromatographic steps including diethylaminoethanol (DEAE)-Sephacel, Sephacryl S-300 and Mono Q column and compare it with human UAP. The molecular weight

  3. Effects of switching from calcium carbonate to lanthanum carbonate on bone mineral metabolism in hemodialysis patients.

    PubMed

    Manabe, Rie; Fukami, Kei; Ando, Ryotaro; Sakai, Kazuko; Kusumoto, Takuo; Hazama, Takuma; Adachi, Takeki; Kaida, Yusuke; Nakayama, Yosuke; Ueda, Seiji; Kohno, Keisuke; Wada, Yoshifumi; Yamagishi, Sho-ichi; Okuda, Seiya

    2013-04-01

    Phosphate binders are useful for the treatment of hyperphosphatemia in hemodialysis (HD) patients. This study was performed to examine the effects of switching from calcium carbonate (CC) to lanthanum carbonate (LC) on bone mineral metabolism and inflammatory markers in HD patients. We conducted 29 stable HD patients receiving CC, which was replaced by LC and followed-up for 12 weeks. Patients underwent determinants of blood chemistries such as serum calcium (Ca), phosphorus, parathyroid hormone (PTH) and vitamin D status, and interleukin-6 (IL-6) mRNA levels in whole blood cells were evaluated by real-time PCR just before and after the treatment with LC. Corrected Ca [corrected] levels were significantly reduced, but serum phosphorus levels (P levels) were unchanged after LC treatment. Switching to LC increased whole-PTH, osteocalcin, 1,25(OH)(2) D(3) levels and 1,25(OH)(2) D(3)/25(OH)D(3) ratio. 1,25(OH)(2) D(3)/25(OH)D(3) ratio was negatively correlated with HD duration. Furthermore, whole blood cell IL-6 mRNA levels were significantly reduced by LC treatment. We provided that the switching from CC to LC improved Ca overload and ameliorated vitamin D and inflammatory status in HD patients. These observations suggest that LC may play a protective role for the progression of atherosclerosis and vascular calcification in these patients. PMID:23586511

  4. Concave urinary crystallines: direct evidence of calcium oxalate crystals dissolution by citrate in vivo.

    PubMed

    Shang, Yun-Feng; Xu, Meng; Zhang, Guang-Na; Ouyang, Jian-Ming

    2013-01-01

    The changes in urinary crystal properties in patients with calcium oxalate (CaOx) calculi after oral administration of potassium citrate (K3cit) were investigated via atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), and zeta potential analyzer. The AFM and SEM results showed that the surface of urinary crystals became concave, the edges and corners of crystals became blunt, the average size of urinary crystallines decreased significantly, and aggregation of urinary crystals was reduced. These changes were attributed to the significant increase in concentration of excreted citrate to 492 ± 118?mg/L after K3cit intake from 289 ± 83?mg/L before K3cit intake. After the amount of urinary citrate was increased, it complexed with Ca(2+) ions on urinary crystals, which dissolved these crystals. Thus, the appearance of concave urinary crystals was a direct evidence of CaOx dissolution by citrate in vivo. The XRD results showed that the quantities and species of urinary crystals decreased after K3cit intake. The mechanism of inhibition of formation of CaOx stones by K3cit was possibly due to the complexation of Ca(2+) with citrate, increase in urine pH, concentration of urinary inhibitor glycosaminoglycans (GAGs), and the absolute value of zeta potential after K3cit intake. PMID:24363634

  5. Concave Urinary Crystallines: Direct Evidence of Calcium Oxalate Crystals Dissolution by Citrate In Vivo

    PubMed Central

    Shang, Yun-Feng; Xu, Meng; Zhang, Guang-Na; Ouyang, Jian-Ming

    2013-01-01

    The changes in urinary crystal properties in patients with calcium oxalate (CaOx) calculi after oral administration of potassium citrate (K3cit) were investigated via atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), and zeta potential analyzer. The AFM and SEM results showed that the surface of urinary crystals became concave, the edges and corners of crystals became blunt, the average size of urinary crystallines decreased significantly, and aggregation of urinary crystals was reduced. These changes were attributed to the significant increase in concentration of excreted citrate to 492 ± 118?mg/L after K3cit intake from 289 ± 83?mg/L before K3cit intake. After the amount of urinary citrate was increased, it complexed with Ca2+ ions on urinary crystals, which dissolved these crystals. Thus, the appearance of concave urinary crystals was a direct evidence of CaOx dissolution by citrate in vivo. The XRD results showed that the quantities and species of urinary crystals decreased after K3cit intake. The mechanism of inhibition of formation of CaOx stones by K3cit was possibly due to the complexation of Ca2+ with citrate, increase in urine pH, concentration of urinary inhibitor glycosaminoglycans (GAGs), and the absolute value of zeta potential after K3cit intake. PMID:24363634

  6. Calcium Carbonate Distribution in the Surface Sediments of the Indian Ocean

    Microsoft Academic Search

    Venkatarathnam Kolla; Allan W. H. Bé; Pierre E. Biscaye

    1976-01-01

    A comprehensive calcium carbonate map for the Indian Ocean surface sediments has been pre- pared from the analysis of about 1200 samples. The percent cbonaidistribution shows the well- known first-order correlation with depth and hence reflects the physiographic peculiarities of the Indian Ocean. Thus on topographic highs such as most of the mid-Indian ridge, Ninety East ridge, etc. the carbonate

  7. Alpha-1-microglobulin: inhibitory effect on calcium oxalate crystallization in vitro and decreased urinary concentration in calcium oxalate stone formers.

    PubMed

    Tardivel, S; Médétognon, J; Randoux, C; Kébédé, M; Drüeke, T; Daudon, M; Hennequin, C; Lacour, B

    1999-08-01

    In the past few years, alpha-1-microglobulin (alpha1m) has been copurified from human urine with bikunin, a potent inhibitor of calcium oxalate (CaOx) crystallization in vitro. In this study, we have purified alpha1m without bikunin contamination and investigated its possible role in CaOx crystallization by in vitro and in vivo studies. Alpha-1m was purified with an anti-alpha1m antibodies CNBr-activated sepharose column. Two molecular species of alpha1m of respectively 30 and 60 kDa were purified. For each protein, two blots of 30 and 60 kDa cross-reacted with anti-alpha1m antibodies, suggesting that these two forms were derived one from the other. Both protein species inhibited CaOx crystallization in a dose-dependent manner in two in vitro tests. In the first test, the presence of alpha1m of 30 kDa (8 microg/ml) in a medium containing 0. 76 mM CaCl(2) (with (45)Ca) and 0.76 mM Ox(NH(4))(2) inhibited CaOx crystallization by 38% as estimated by supernatant radioactivity after 1 h of agitation. In the second test, CaOx kinetics were examined for 3 to 10 min in a turbidimetric model at 620 nm. The presence of alpha1m of 30 kDa in a medium containing 4 mM CaCl(2) and 0.5 mM Na(2)Ox inhibited CaOx crystallization by 41.5%, as estimated by the slope modification of turbidimetric curve. Alpha-1m can be considered as another inhibitor of urinary CaOx crystal formation, as shown by the present in vitro studies. Using an ELISA assay, we found that urinary alpha1m concentration was significantly lower in 31 CaOx stone formers than in 18 healthy subjects (2.95 +/- 0.29 vs 5.34 +/- 1.08 mg/l respectively, P = 0.01). The decreased concentration of alpha1m in CaOx stone formers could be responsible in these patients, at least in part, for an increased risk of CaOx crystalluria. PMID:10460893

  8. Revisiting spatial distribution and biochemical composition of calcium-containing crystals in human osteoarthritic articular cartilage

    PubMed Central

    2013-01-01

    Introduction Calcium-containing (CaC) crystals, including basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP), are associated with destructive forms of osteoarthritis (OA). We assessed their distribution and biochemical and morphologic features in human knee OA cartilage. Methods We prospectively included 20 patients who underwent total knee replacement (TKR) for primary OA. CaC crystal characterization and identification involved Fourier-transform infra-red spectrometry and scanning electron microscopy of 8 to 10 cartilage zones of each knee, including medial and lateral femoral condyles and tibial plateaux and the intercondyle zone. Differential expression of genes involved in the mineralization process between cartilage with and without calcification was assessed in samples from 8 different patients by RT-PCR. Immunohistochemistry and histology studies were performed in 6 different patients. Results Mean (SEM) age and body mass index of patients at the time of TKR was 74.6 (1.7) years and 28.1 (1.6) kg/m², respectively. Preoperative X-rays showed joint calcifications (chondrocalcinosis) in 4 cases only. The medial femoro-tibial compartment was the most severely affected in all cases, and mean (SEM) Kellgren-Lawrence score was 3.8 (0.1). All 20 OA cartilages showed CaC crystals. The mineral content represented 7.7% (8.1%) of the cartilage weight. All patients showed BCP crystals, which were associated with CPP crystals for 8 joints. CaC crystals were present in all knee joint compartments and in a mean of 4.6 (1.7) of the 8 studied areas. Crystal content was similar between superficial and deep layers and between medial and femoral compartments. BCP samples showed spherical structures, typical of biological apatite, and CPP samples showed rod-shaped or cubic structures. The expression of several genes involved in mineralization, including human homolog of progressive ankylosis, plasma-cell-membrane glycoprotein 1 and tissue-nonspecific alkaline phosphatase, was upregulated in OA chondrocytes isolated from CaC crystal-containing cartilages. Conclusions CaC crystal deposition is a widespread phenomenon in human OA articular cartilage involving the entire knee cartilage including macroscopically normal and less weight-bearing zones. Cartilage calcification is associated with altered expression of genes involved in the mineralisation process. PMID:24004678

  9. Calcium self-diffusion in natural diopside single crystals

    NASA Astrophysics Data System (ADS)

    Dimanov, Alexandre; Jaoul, Olivier; Sautter, Violaine

    1996-11-01

    We have measured the diffusion coefficient of 44Ca along and perpendicular to c direction in natural Fe-bearing (˜2 at.%) diopside single crystals. Specimens were annealed at temperatures ranging from 1000 to 1250°C, with controlled oxygen fugacity. Diffusion profiles were analysed by Rutherford Back-Scattering Spectrometry (RBS) of ?-particles. The diffusion of Ca is isotropic along c and b directions. In addition, the results clearly show two distinct diffusional regimes for the natural diopside, revealed by silica precipitates occurrence in the diopside matrix when T ? 1150°C. In this case the oxygen partial pressure pO 2 does not influence the self-diffusion coefficient which is characterized by the activation energy E = 396 ± 38 kJ/mol. For T ? 1100°C the diffusional process has a lower activation energy ( E = 264 ± 33 kJ/mol) and varies as ( pO 2) -0.14±0.01 in the investigated range (from 10 -16 atm to 10 -6 atm). These results are consistent with previously reported results on electrical conductivity (Huebner and Voigt, 1988) and high temperature plastic deformation of natural diopside single crystals (Jaoul and Raterron, 1994). According to the point defects model, elaborated by Jaoul and Raterron (1994), the diffusional mechanism of Ca should be essentially interstitial. Furthermore, this mechanism should be the same for different diopside samples with iron content ranging from 0.4 to 2.42 at.%. Indeed, for Ca diffusion in synthetic diopside (0.4 at.% Fe) the activation enthalpy is very similar (281 ± 26 kJ/mol, Dimanov and Ingrin, 1995). On the other hand, the Fe content indoubtly influences the preexponential factor. The present paper reports Ca self-diffusion in diopside as a function of T, pO 2 crystallographic orientation, and Fe content. In fact, among all diffusion coefficients previously reported in diopside, but Si, DCa is the lowest. Thereby, Ca should be a kinetically limiting species for diffusion-controlled processes such as plastic deformation and cation exchanges. For instance, Ca self-diffusion controls Ca?Mg exchanges between pyroxenes. Then, our results could be helpful to better understand the closure behaviour (Dodson, 1973, 1976) of the Clinopyroxene-Orthopyroxene geothermometer.

  10. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    NASA Astrophysics Data System (ADS)

    Rastsvetaeva, R. K.; Aksenov, S. M.; Verin, I. A.

    2010-07-01

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) Å, b = 17.1823(4) Å, c = 23.5718(5) Å, ? = 90°, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with | F| > 7?( F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula ( Z = 4) is Ca2Mg{2/IV}Fe{2/(2+)IV}[Al{14/VI}O31(OH)][Al{2/IV}O][AlIV]ALIV(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe2+ tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  11. Recovery of calcium carbonate from steelmaking slag and utilization for acid mine drainage pre-treatment.

    PubMed

    Mulopo, J; Mashego, M; Zvimba, J N

    2012-01-01

    The conversion of steelmaking slag (a waste product of the steelmaking process) to calcium carbonate (CaCO(3)) was tested using hydrochloric acid, ammonium hydroxide and carbon dioxide via a pH-swing process. Batch reactors were used to assess the technical feasibility of calcium carbonate recovery and its use for pre-treatment of acid mine drainage (AMD) from coal mines. The effects of key process parameters, such as the amount of acid (HCl/calcium molar ratio), the pH and the CO(2) flow rate were considered. It was observed that calcium extraction from steelmaking slag significantly increased with an increase in the amount of hydrochloric acid. The CO(2) flow rate also had a positive effect on the carbonation reaction rate but did not affect the morphology of the calcium carbonate produced for values less than 2 L/min. The CaCO(3) recovered from the bench scale batch reactor demonstrated effective neutralization ability during AMD pre-treatment compared with the commercial laboratory grade CaCO(3). PMID:22643421

  12. Calcium carbonate distribution in the surface sediments of the Indian Ocean

    Microsoft Academic Search

    Venkatarathnam Kolla; Allan W. H. Bé; Pierre É. Biscaye

    1976-01-01

    A comprehensive calcium carbonate map for the Indian Ocean surface sediments has been prepared from the analysis of about 1200 samples. The percent carbonate distribution shows the well-known first-order correlation with depth and hence reflects the physiographic peculiarities of the Indian Ocean. Thus on topographic highs such as most of the mid-Indian ridge, Ninety East ridge, etc. the carbonate is

  13. Crystal structure of complex natural aluminum magnesium calcium iron oxide

    SciTech Connect

    Rastsvetaeva, R. K., E-mail: rast@ns.crys.ras.ru; Aksenov, S. M.; Verin, I. A. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2010-07-15

    The structure of a new natural oxide found near the Tashelga River (Eastern Siberia) was studied by X-ray diffraction. The pseudo-orthorhombic unit cell parameters are a = 5.6973(1) A, b = 17.1823(4) A, c = 23.5718(5) A, {beta} = 90{sup o}, sp. gr. Pc. The structure was refined to R = 0.0516 based on 4773 reflections with vertical bar F vertical bar > 7{sigma}(F) taking into account the twin plane perpendicular to the z axis (the twin components are 0.47 and 0.53). The crystal-chemical formula (Z = 4) is Ca{sub 2}Mg{sub 2}{sup IV}Fe{sub 2}{sup (2+)IV}[Al{sub 14}{sup VI}O{sub 31}(OH)][Al{sub 2}{sup IV}O][Al{sup IV}]AL{sup IV}(OH)], where the Roman numerals designate the coordination of the atoms. The structure of the mineral is based on wide ribbons of edge-sharing Al octahedra (an integral part of the spinel layer). The ribbons run along the shortest x axis and are inclined to the y and z axes. The adjacent ribbons are shifted with respect to each other along the y axis, resulting in the formation of step-like layers in which the two-ribbon thickness alternates with the three-ribbon thickness. Additional Al octahedra and Mg and Fe{sup 2+} tetrahedra are located between the ribbons. The layers are linked together to form a three-dimensional framework by Al tetrahedra, Ca polyhedra, and hydrogen bonds with the participation of OH groups.

  14. pH control in biological systems using calcium carbonate.

    PubMed

    Salek, S S; van Turnhout, A G; Kleerebezem, R; van Loosdrecht, M C M

    2015-05-01

    Due to its abundance, calcium carbonate (CaCO3 ) has high potentials as a source of alkalinity for biotechnological applications. The application of CaCO3 in biological systems as neutralizing agent is, however, limited due to potential difficulties in controlling the pH. The objective of the present study was to determine the dominant processes that control the pH in an acid-forming microbial process in the presence of CaCO3 . To achieve that, a mathematical model was made with a minimum set of kinetically controlled and equilibrium reactions that was able to reproduce the experimental data of a batch fermentation experiment using finely powdered CaCO3 . In the model, thermodynamic equilibrium was assumed for all speciation, complexation and precipitation reactions whereas, rate limited reactions were included for the biological fatty acid production, the mass transfer of CO2 from the liquid phase to the gas phase and the convective transport of CO2 out of the gas phase. The estimated pH-pattern strongly resembled the measured pH, suggesting that the chosen set of kinetically controlled and equilibrium reactions were establishing the experimental pH. A detailed analysis of the reaction system with the aid of the model revealed that the pH establishment was most sensitive to four factors: the mass transfer rate of CO2 to the gas phase, the biological acid production rate, the partial pressure of CO2 and the Ca(+2) concentration in the solution. Individual influences of these factors on the pH were investigated by extrapolating the model to a continuously stirred-tank reactor (CSTR) case. This case study indicates how the pH of a commonly used continuous biotechnological process could be manipulated and adjusted by altering these four factors. Achieving a better insight of the processes controlling the pH of a biological system using CaCO3 as its neutralizing agent can result in broader applications of CaCO3 in biotechnological industries. Biotechnol. Bioeng. 2015;112: 905-913. © 2014 Wiley Periodicals, Inc. PMID:25425281

  15. Investigation of high-reactivity calcium carbonate sorbent for enhanced SOâ capture

    Microsoft Academic Search

    Abhijit Ghosh-Dastidar; Suhas K. Mahuli; Rajeev Agnihotri; Liang-Shih Fan

    1996-01-01

    Kinetics of ultrafast, high-temperature sulfation is investigated for two calcium carbonates from different sources, a commercial calcium hydroxide and a laboratory-made modified hydrated lime powder. Time-resolved kinetic data are obtained for a 0--600 ms time scale at a temperature of 1,080 C with in-situ particle size classification. A mean particle size of 3.9 μm is considered for sorbent comparison studies.

  16. Inhibitive effect of calcium gluconate and sodium molybdate on carbon steel

    Microsoft Academic Search

    S. M. A. Shibli; V. Anitha Kumary

    2004-01-01

    There is an increasing demand for eco-friendly inhibitors for use in cooling water systems. Both calcium gluconates and molybdate are eco-friendly, non-toxic chemicals. The corrosion inhibition of calcium gluconate and sodium molybdate on carbon steel in neutral aqueous media was evaluated by means of weight loss, electrochemical polarisation and impedance techniques. A synergistic effect was observed when these two eco-friendly

  17. Therapeutic effect of Xue Niao An on glyoxylate-induced calcium oxalate crystal deposition based on urinary metabonomics approach

    PubMed Central

    Peng, Zhongjiang; Chen, Wei; Gao, Songyan; Su, Li; Li, Na; Wang, Li; Lou, Ziyang; Dong, Xin; Guo, Zhiyong

    2014-01-01

    The anti-nephrolithiasis effect of Xue Niao An (XNA) capsules is explored by analyzing urine metabolic profiles in mouse models, with ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). An animal model of calcium oxalate crystal renal deposition was established in mice by intra-abdominal injection of glyoxylate. Then, treatment with XNA by intra-gastric administration was performed. At the end of the study, calcium deposition in kidney was measured by Von Kossa staining under light microscopy, and the Von Kossa staining changes showed that XNA significantly alleviated the calcium oxalate crystal deposition. Meanwhile, urine samples for fifteen metabolites, including amino acids and fatty acids, with significant differences were detected in the calcium oxalate group, while XNA treatment attenuated metabolic imbalances. Our study indicated that the metabonomic strategy provided comprehensive insight on the metabolic response to XNA treatment of rodent renal calcium oxalate deposition. PMID:25411524

  18. A Systematic Examination of the Morphogenesis of Calcium Carbonate in the Presence of a Double-Hydrophilic Block Copolymer

    E-print Network

    Qi, Limin

    A Systematic Examination of the Morphogenesis of Calcium Carbonate in the Presence of a Double [polymer]/[CaCO3] turned out to be important parameters for the morphogenesis of CaCO3, whereas a moderate ´ block co- polymers ´ calcium ´ calcium carbo- nate ´ colloids ´ morphogenesis Introduction The synthesis

  19. Carbon Nanotube-Reinforced Thermotropic Liquid Crystal Polymer Nanocomposites

    E-print Network

    Kim, Jun Young

    This paper focuses on the fabrication via simple melt blending of thermotropic liquid crystal polyester (TLCP) nanocomposites reinforced with a very small quantity of modified carbon nanotube (CNT) and the unique effects ...

  20. Calcium Carbonate Formation by Synechococcus sp. Strain PCC 8806 and Synechococcus sp. Strain PCC 8807

    SciTech Connect

    Lee, Brady D.; William A. Apel; Michelle R. Walton

    2006-12-01

    Precipitation of CaCO3 catalyzed by the growth and physiology of cyanobacteria in the Genus Synechococcus represents a potential mechanism for sequestration of CO2 produced during the burning of coal for power generation. Microcosm experiments were performed in which Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807 were tested for their ability to calcify when exposed to a fixed calcium concentration of 3.4 mM and bicarbonate concentrations of 0.5, 1.25 and 2.5 mM. Disappearance of soluble calcium was used as an indicator of CaCO3 formation; results from metabolically active microcosms were compared to controls with no cells or no carbonate added. Synechococcus sp. strain PCC 8806 removed calcium continuously over the duration of the experiment with approximately 18.6 mg of calcium in the solid phase. Calcium removal occurred over a two-day time period when Synechococcus sp. strain PCC 8807 was tested and only 8.9 mg of calcium was removed in the solid phase. The ability of the cyanobacteria to create an alkaline growth environment appeared to be the primary factor responsible for CaCO3 precipitation in these experiments. Removal of inorganic carbon by fixation into biomass was insignificant compared to the mass of inorganic carbon removed by incorporation into the growing CaCO3 solid.

  1. Original article Availability of calcium from skim milk, calcium sulfate

    E-print Network

    Paris-Sud XI, Université de

    Original article Availability of calcium from skim milk, calcium sulfate and calcium carbonate; accepted 19 November 1999) Abstract --Dairy products provide abundant, accessible calcium for humans, while some calcium sulfate-rich mineral waters could provide appreciable amounts of calcium

  2. Gamma-irradiated calcium succinate monohydrate single crystal investigation with EPR technique.

    PubMed

    Yarba??, Zeynep; Karabulut, Bünyamin; Karabulut, Abdulhalik

    2011-12-01

    In this study, EPR investigation of gamma-irradiated calcium succinate monohydrate [CaC(4)H(4)O(4)·H(2)O] single crystal has been carried out at room temperature. The compound crystallizes in monoclinic symmetry with the unit-cell dimensions: a=11.952(2)?, b=9.691(2)?, c=11.606(2)?, ?=108.81(1)°. The observed lines in the EPR spectra reveal the formation of C?H(?)CH(?1)H(?2) radical after irradiating [CaC(4)H(4)O(4)·H(2)O] single crystal. The angular variations of EPR spectra have shown that the radical type has only one site in three perpendicular planes. The principal g and a values and direction cosines of C?H(?)CH(?1)H(?2) radical have been determined. PMID:21920802

  3. Basic calcium phosphate crystal-induced Egr-1 expression stimulates mitogenesis in human fibroblasts

    SciTech Connect

    Zeng, Xiao R. [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States); Sun Yubo [Division of Rheumatology and Immunology, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101 (United States); Wenger, Leonor [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States); Cheung, Herman S. [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States) and Division of Rheumatology and Immunology, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101 (United States) and Research Service and the Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Miami, FL 33125 (United States)]. E-mail: hcheung@med.miami.edu

    2005-05-13

    Previously, we have reported that basic calcium phosphate (BCP) crystals stimulate mitogenesis and synthesis of matrix metalloproteinases in cultured human foreskin and synovial fibroblasts. However, the detailed mechanisms involved are still unclear. In the present study, using RT-PCR and Egr-1 promoter analysis we showed that BCP crystals could stimulate early growth response gene Egr-1 transcription through a PKC{alpha}-dependent p44/p42 MAPK pathway. Using a retrovirus gene expression system (Clontech) to overexpress Egr-1 in human fibroblast BJ-1 cells resulted in promotion of mitogenesis measured either by MTT cell proliferation analysis or by direct cell counting. The results demonstrate that Egr-1 may play a key role in mediating BCP crystal-induced synovial fibroblast mitogenesis.

  4. Synthesis of novel amorphous calcium carbonate by sono atomization for reactive mixing.

    PubMed

    Kojima, Yoshiyuki; Kanai, Makoto; Nishimiya, Nobuyuki

    2012-03-01

    Droplets of several micrometers in size can be formed in aqueous solution by atomization under ultrasonic irradiation at 2 MHz. This phenomenon, known as atomization, is capable of forming fine droplets for use as a reaction field. This synthetic method is called SARM (sono atomization for reactive mixing). This paper reports on the synthesis of a novel amorphous calcium carbonate formed by SARM. The amorphous calcium carbonate, obtained at a solution concentration of 0.8 mol/dm(3), had a specific surface area of 65 m(2)/g and a composition of CaCO(3)•0.5H(2)O as determined using thermogravimetric/differential thermal analysis (TG-DTA). Because the ACC had a lower hydrate composition than conventional amorphous calcium carbonate (ACC), the ACC synthesized in this paper was very stable at room temperature. PMID:21788149

  5. Carbonic anhydrase activity in a calcium-mobilizing epithelium of the crustacean Orchestia cavimana during molting.

    PubMed

    Meyran, J C; Graf, F; Fournié, J

    1987-01-01

    We investigated the involvement of the enzyme, carbonic anhydrase, in the calcification-decalcification processes occurring in the posterior caeca of the midgut of the terrestrial crustacean, Orchestia cavimana, before and after exuviation. This enzyme was ultrahistochemically localized throughout the membranes of the caecal epithelium as well as extracellularly, i.e., within pre-exuvial calcareous concretions and postexuvial calcified spherules. During the molt cycle, the pattern of carbonic anhydrase activity in the posterior caeca was correlated with the calcium content at this level. Acetazolamide treatment in vivo inhibited about 50% of the calcium uptake during both pre-exuvial secretion and postexuvial reabsorption. The role of carbonic anhydrase in this mineralizing-demineralizing epithelium is discussed and compared with that of other mechanisms involved in this calcium turnover. PMID:3123431

  6. MEDICAGO TRUNCATULA MUTANTS DEMONSTRATE THE ROLE OF PLANT CALCIUM OXALATE CRYSTALS AS AN EFFECTIVE DEFENSE AGAINST CHEWING INSECTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate is the most abundant insoluble mineral found in plants and its crystals have been reported in over 200 plant families. In the barrel medic, Medicago truncatula Gaertn., these crystals accumulate predominantly in a sheath surrounding secondary veins of leaves. Mutants of M. truncatul...

  7. Enhancement of carbon nanotube photoluminescence by photonic crystal nanocavities

    E-print Network

    Maruyama, Shigeo

    Enhancement of carbon nanotube photoluminescence by photonic crystal nanocavities R. Watahiki,1 T 153-8505, Japan Photonic crystal nanocavities are used to enhance photoluminescence from single slabs and confocal microscopy is used to characterize the devices. Photoluminescence spectra and images

  8. CALCIUM HYDROXIDE AND CALCIUM CARBONATE PARTICLE SIZE EFFECTS ON REACTIVITY WITH SULFUR DIOXIDE

    EPA Science Inventory

    The paper reports results of measurements of the effect of in situ calcium-based sorbent particle size upon reactivity with 3000 ppm SO2 in an 1100 c drop-tube furnace, using on-line collection of the reacted sorbent with a particle cascade impactor. Significant agglomeration occ...

  9. Aqueous extract of Costus arabicus inhibits calcium oxalate crystal growth and adhesion to renal epithelial cells.

    PubMed

    de Cógáin, Mitra R; Linnes, Michael P; Lee, Hyo Jung; Krambeck, Amy E; de Mendonça Uchôa, Julio Cezar; Kim, Sung-Hoon; Lieske, John C

    2015-04-01

    Costus arabicus L. (C. arabicus) is a plant used in Brazilian folk medicine to treat urolithiasis; however, its mechanism of action is unclear. The interaction between calcium oxalate (CaOx) crystals and the renal epithelium is important in calculogenesis, and compounds that modulate this process represent candidate therapeutic agents for stone prevention. Therefore, we assessed the inhibitory activity of C. arabicus on CaOx crystallization and the interaction of CaOx crystals with the renal epithelium. A seeded CaOx monohydrate (COM) crystallization system was used to study the effect of C. arabicus on crystal growth. Madin Darby canine kidney (MDCK) cells were used to study [(14)C] COM crystal adhesion in the presence and absence of an aqueous extract of C. arabicus. Cytotoxicity was assessed using a tetrazolium (MTS) cell proliferation assay. Aqueous extracts of C. arabicus decreased crystal growth in a concentration-dependent fashion. Precoating crystals with C. arabicus extract prevented their adhesion to MDCK cells, while pretreating cells did not show any effect. The extract was non-cytotoxic in concentrations of at least 1 mg/ml, which is likely above concentrations achievable in the urine following oral ingestion and excretion. No inhibitory activity was found in hexane, methyl chloride, n-butanol and ethyl acetate fractions of an ethanol extract of the herb. An aqueous extract of C. arabicus may disrupt calculogenesis by interacting with CaOx crystal surfaces. Activity was present in the aqueous extract; therefore, this agent may be bioavailable when administered orally. Fractionation results suggest that the active agent might be a polar polysaccharide. Further identification and characterization along these lines may be warranted. PMID:25652357

  10. Absorption behavior of vinyl chloride\\/calcium carbonate and pressure\\/temperature\\/conversion relationship for vinyl chloride suspension polymerization in the presence of calcium carbonate

    Microsoft Academic Search

    Bao Yong-zhong; Zhang Li-feng; Huang Zhi-ming; Weng Zhi-xue

    2003-01-01

    The absorption of vinyl chloride (VC) on surface-treated light-grade and nano-scale calcium carbonate (CaCO3), and VC suspension polymerization in the presence of CaCO3 were carried out in a 5 L autoclave. It showed that the absorption of VC on CaCO3 increased with the partial pressure of VC up to a critical point. Nano-scale CaCO3 was more effective in absorbing VC

  11. Medicago truncatula Mutants Demonstrate the Role of Plant Calcium Oxalate Crystals as an Effective Defense against Chewing Insects1

    PubMed Central

    Korth, Kenneth L.; Doege, Sarah J.; Park, Sang-Hyuck; Goggin, Fiona L.; Wang, Qin; Gomez, S. Karen; Liu, Guangjie; Jia, Lingling; Nakata, Paul A.

    2006-01-01

    Calcium oxalate is the most abundant insoluble mineral found in plants and its crystals have been reported in more than 200 plant families. In the barrel medic Medicago truncatula Gaertn., these crystals accumulate predominantly in a sheath surrounding secondary veins of leaves. Mutants of M. truncatula with decreased levels of calcium oxalate crystals were used to assess the defensive role of this mineral against insects. Caterpillar larvae of the beet armyworm Spodoptera exigua Hübner show a clear feeding preference for tissue from calcium oxalate-defective (cod) mutant lines cod5 and cod6 in choice test comparisons with wild-type M. truncatula. Compared to their performance on mutant lines, larvae feeding on wild-type plants with abundant calcium oxalate crystals suffer significantly reduced growth and increased mortality. Induction of wound-responsive genes appears to be normal in cod5 and cod6, indicating that these lines are not deficient in induced insect defenses. Electron micrographs of insect mouthparts indicate that the prismatic crystals in M. truncatula leaves act as physical abrasives during feeding. Food utilization measurements show that, after consumption, calcium oxalate also interferes with the conversion of plant material into insect biomass during digestion. In contrast to their detrimental effects on a chewing insect, calcium oxalate crystals do not negatively affect the performance of the pea aphid Acyrthosiphon pisum Harris, a sap-feeding insect with piercing-sucking mouthparts. The results confirm a long-held hypothesis for the defensive function of these crystals and point to the potential value of genes controlling crystal formation and localization in crop plants. PMID:16514014

  12. Controlled crystal growth of calcium phosphate on titanium surface by NaOH-treatment

    NASA Astrophysics Data System (ADS)

    Feng, Q. L.; Wang, H.; Cui, F. Z.; Kim, T. N.

    1999-04-01

    A simple supersaturated calcification solution (SCS) was used to deposit calcium phosphate (Ca-P) on the surface of NaOH-treated titanium (NaOH-Ti), in order to study the corresponding deposition mechanism of calcium phosphate (Ca-P). No Ca-P coating from SCS was found on titanium without NaOH-treatment, while NaOH-Ti possessed the capability to induce a Ca-P coating on the titanium surface. Octacalcium phosphate (OCP) crystals were first grown on an NaOH-Ti surface, followed by hydroxyapatite (HA) with a [0 0 1] preferential orientation on OCP. It is found that two factors controlled the growth of Ca-P crystals on NaOH-Ti from SCS. First, the surface morphology of NaOH-Ti characterized with crevices seems to be beneficial for inducing a Ca-P coating from SCS; second, the basic hydroxyl, Ti-OH, radical has increased in NaOH-Ti with the increase of treating time and concentration, which facilitate the nucleation of Ca-P crystals.

  13. Carboxylated molecules regulate magnesium content of amorphous calcium carbonates during calcification

    PubMed Central

    Wang, Dongbo; Wallace, Adam F.; De Yoreo, James J.; Dove, Patricia M.

    2009-01-01

    With the realization that many calcified skeletons form by processes involving a precursor phase of amorphous calcium carbonate (ACC), a new paradigm for mineralization is emerging. There is evidence the Mg content in biogenic ACC is regulated by carboxylated (acidic) proteins and other macromolecules, but the physical basis for such a process is unknown. We test the hypothesis that ACC compositions express a systematic relationship to the chemistry of carboxyl-rich biomolecules. A series of inorganic control experiments were conducted to establish the dependence of Mg/Ca ratios in ACC on solution composition. We then determined the influence of a suite of simple carboxylated organic acids on Mg content. Molecules with a strong affinity for binding Ca compared with Mg promote the formation of Mg-enriched ACC that is compositionally equivalent to high-magnesium calcites and dolomite. Measurements show Mg/Ca ratios are controlled by a predictable dependence upon the binding properties of the organic molecules. The trend appears rooted in the conformation and electrostatic potential topology of each molecule, but dynamic factors also may be involved. The dependence suggests a physical basis for reports that specific sequences of calcifying proteins are critical to modulating mineralization. Insights from this study may provide a plausible explanation for why some biogenic carbonates and carbonaceous cements often contain higher Mg signatures than those that are possible by classical crystal growth processes. The findings reiterate the controls of microenvironment on mineralization and suggest an origin of compositional offsets, or vital effects, long recognized by the paleoclimate community. PMID:19955417

  14. Effect of calcium carbonate on clinical compliance of apatitic calcium phosphate bone cement.

    PubMed

    Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

    1997-01-01

    Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time, and the ultimate compressive strength. Two cement formulations were tested. Biocement F was made of a powder containing alpha-tertiary calcium phosphate, precipitated hydroxyapatite, and monetite. Biocement D powder also contained CaCO3. The liquid/powder (L/P) ratio of the cement paste and the accelerator concentrations (% Na2HPO4) in the cement liquid were varied. For Biocement F there was a small area of combinations of L/P ratio and percent Na2HPO4 for which all clinical requirements were satisfied. This area covered only pastes that could be applied as doughs. However, Biocement D showed a much larger area of full compliance and it covered both doughlike and injectable pastes. PMID:9421757

  15. Synovial chondromatosis of the temporomandibular joint with calcium pyrophosphate dihydrate crystal deposition disease (pseudogout)

    PubMed Central

    Matsumura, Y; Nomura, J; Nakanishi, K; Yanase, S; Kato, H; Tagawa, T

    2012-01-01

    This report describes a very rare case of synovial chondromatosis with deposition of calcium pyrophosphate dihydrate (CPPD) crystals (pseudogout) in the temporomandibular joint (TMJ) of a 46-year-old male patient. Synovial chondromatosis is a non-neoplastic disease characterized by metaplasia of the connective tissue leading to chondrogenesis in the synovial membrane. Pseudogout is an inflammatory disease of the joints caused by the deposition of CPPD, producing similar symptoms to those observed in gout but not hyperuricaemia. Both diseases commonly affect the knee, hip and elbow joints, but rarely affect the TMJ. PMID:23166363

  16. The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

    USGS Publications Warehouse

    Kramer, Henry

    1956-01-01

    A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

  17. Factors affecting ex-situ aqueous mineral carbonation using calcium and magnesium silicate minerals

    SciTech Connect

    Gerdemann, Stephen J.; Dahlin, David C.; O'Connor, William K.; Penner, Larry R.; Rush, G.E.

    2004-01-01

    Carbonation of magnesium- and calcium-silicate minerals to form their respective carbonates is one method to sequester carbon dioxide. Process development studies have identified reactor design as a key component affecting both the capital and operating costs of ex-situ mineral sequestration. Results from mineral carbonation studies conducted in a batch autoclave were utilized to design and construct a unique continuous pipe reactor with 100% recycle (flow-loop reactor). Results from the flow-loop reactor are consistent with batch autoclave tests, and are being used to derive engineering data necessary to design a bench-scale continuous pipeline reactor.

  18. Influence of sodium dodecyl sulfate and static magnetic field on the properties of freshly precipitated calcium carbonate.

    PubMed

    Chibowski, Emil; Szczes, Aleksandra; Holysz, Lucyna

    2005-08-30

    Properties of calcium carbonate precipitated from aqueous solutions of CaCl(2) and Na(2)CO(3) in the presence of sodium dodecyl sulfate (SDS) and S-S 0.1 T magnetic field (MF) were studied. The nucleation and precipitation processes of CaCO(3) were investigated by pH and zeta potential measurements at 20 +/- 1 degrees C up to 2 h after mixing the solutions. Also the amounts of calcium carbonate deposited on the glass surfaces and its structure were examined. It was found that SDS influences the kinetics of precipitation, crystallographic forms, and crystal size of CaCO(3). The SDS effects are more pronounced in MF presence. A small amount of SDS accelerates transformation of vaterite into calcite, whereas increasing surfactant concentration moderates such a transformation. On the other hand, in all the systems, MF in the presence of SDS causes a slower transformation of vaterite into calcite. These effects are reflected in pH and zeta potential changes, although there is no clear dependence between the SDS amount present during the precipitation and changes of the parameters investigated. It seems that MF effect is most significant at a defined optimal SDS concentration. The results, however, do not allow suggestion of any detailed mechanism of the field interaction. PMID:16114911

  19. Ab initio simulation on the crystal structure and elastic properties of carbonated apatite.

    PubMed

    Ren, Fuzeng; Lu, Xiong; Leng, Yang

    2013-10-01

    Ab initio quantum mechanical (QM) calculations were employed to study the crystal structure and elastic properties of carbonated apatite (CAp). Two locations for the carbonate ion in the apatite lattice were considered: carbonate substituting for OH(-) ion (type-A), and for PO4(3-) ion (type-B) with possible charge compensation mechanisms. A combined type-AB substitution (two carbonate ions replacing one phosphate group and one hydroxyl group, respectively) was also investigated. The results show that the most energetically stable substitution is type-AB, followed by type-A and then type-B. The most stable configuration of type-A has its carbonate triangular plane almost parallel to c-axis at z=0.46. The lowest energy configuration of type-B is that with a sodium ion substituting for a calcium ion for charge balance and the carbonate lying on the b/c-plane of apatite. Lattice parameter changes after carbonate substitution in hydroxyapatite (HA) agree with reported experimental results qualitatively: for type-A, lattice parameter a increases but c decreases; and for type-B, lattice parameter a decreases but c increases. Using the calculated CAp stable structures, we also calculated the elastic properties of CAp and compared them with those of HA and biological apatites. PMID:23811277

  20. Solute carbon and carbon segregation in magnesium oxide single crystals — a secondary ion mass spectrometry study

    Microsoft Academic Search

    Friedemann Freund

    1986-01-01

    If carbon is to be analyzed by secondary ion mass spectroscopy (SIMS) in an oxide such as MgO, one has to know how the carbon is incorporated in the oxide host structure, before a successful experiment can be planned. If the carbon impurities derive from dissolved CO2 component which form a solid solution while the crystal grew from a melt

  1. Catechin prevents the calcium oxalate monohydrate induced renal calcium crystallization in NRK-52E cells and the ethylene glycol induced renal stone formation in rat

    PubMed Central

    2013-01-01

    Background Reactive oxygen species play important roles in renal calcium crystallization. In this study, we examined the effects of catechin, which have been shown to have antioxidant properties on the renal calcium crystallization. Methods In the vitro experiment, the changes of the mitochondrial membrane potential, expression of superoxide dismutase (SOD), 4-hydroxynonenal (4-HNE), cytochrome c, and cleaved caspase 3 were measured to show the effects of catechin treatment on the NRK-52E cells induced by calcium oxalate monohydrate (COM). In the vivo study, Sprague–Dawley rats were administered 1% ethylene glycol (EG) to generate a rat kidney stone model and then treated with catechin (2.5 and 10 mg/kg/day) for 14 days. The urine and serum variables were dected on 7 and 14 days after EG administration. The expression of cytochrome c, cleaved caspase 3, SOD, osteopontin (OPN), malondialdehyde (MDA), 8-hydroxy-2?-deoxyguanosine (8-OHdG) in kidney were measured. Furthermore, the mitochondrial microstructure in the kidney was also examined by transmission electron microscopy. Results Catechin treatment could prevent the changes in mitochondrial membrane potential and expression of SOD, 4-HNE, cytochrome c, and cleaved caspase 3 in NRK-52E cells induced by the COM. For the in vivo experiments, the EG administration induced renal calcium crystallization was also prevented by the catechin. The expression of SOD, OPN, MDA, OPN and 8-OHdG, were increased after EG administration and this increase was diminished by catechin. Moreover, catechin also prevented EG induced mitochondrial collapse in rat. Conclusions Catechin has preventive effects on renal calcium crystallization both in vivo and in vitro, and provide a potential therapeutic treatment for this disease. PMID:24044655

  2. Interaction of organic compounds with calcium carbonate--III. Amino acid composition of sorbed layers

    Microsoft Academic Search

    Peter J. Müller; Erwin Suess

    1977-01-01

    Nitrogenous organic compounds in sorbed surface layers and in calcified organic matter associated with calcium carbonate sediment particles consist of 40-50% amino acids, 2% amino sugars and 25% ammonia. In grain size classes > 20 m these compounds are mainly contained in the calcified protein of carbonate secreting organisms but with smaller grain sizes--and consequently increased specific surface area--they are

  3. An atlas of the distribution of calcium carbonate in sediments of the deep sea

    Microsoft Academic Search

    David E. Archer

    1996-01-01

    The goals of this study were to: (1) digest available sedimentary data into a format appropriate for validating models of oceanic calcium carbonate (CaCOâ) dynamics, (2) estimate the inventory of deep sea CaCOâ available for neutralization of fossil fuel carbon dioxide, and (3) determine the variability of CaCOâ preservation relative to local saturation conditions. CaCOâ concentrations in global deep sea

  4. Calcium pyrophosphate dihydrate crystal deposition disease after anterior cruciate ligament reconstruction.

    PubMed

    Minezaki, T; Tomatsu, T; Hanada, K

    1998-09-01

    We report the case of a 34-year-old woman who presented with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease shortly after anterior cruciate ligament (ACL) reconstruction using a polyester artificial ligament (Leeds-Keio; Neoligaments, Leeds, England). The patient had earlier undergone a medial collateral ligament repair of a sprain to her right knee incurred while skiing. Nine years later, she underwent ACL reconstruction. Seventeen months after ACL reconstruction, calcification was observed on radiographs of the medial and lateral menisci. Based on these calcifications and polarized light microscopic findings of the joint fluid, the diagnosis was made of CPPD crystal deposition. CPPD deposition appeared to have resulted from intra-articular damage incurred during ACL reconstruction as well as prolonged anterior instability. PMID:9754486

  5. Cervical radiculomyelopathy caused by deposition of calcium pyrophosphate dihydrate crystals in the ligamenta flava. Case report.

    PubMed

    Kawano, N; Yoshida, S; Ohwada, T; Yada, K; Sasaki, K; Matsuno, T

    1980-02-01

    A case of cervical radiculomyelopathy caused by multiple calcified nodules in the ligamenta flava is presented. Roentgenological examination of the cervical spine showed radiopaque nodular lesions, 7 x 7 x 5 mm in size, located in the paramedian portion of the posterior spinal canal. The nodules were removed surgically and they were confirmed to be calcifications of ligamenta flava. Microscopic examination of the nodules with the polarized light revealed extensive deposition of crystals. By x-ray diffraction study, the crystal was determined as calcium pyrophosphate dihydrate (CPPD: Ca2P2O7 . 2H2O). Although CPPD deposition in the cartilage has been known as pseudo-gout syndrome, deposition in the ligament has been reported only in a few cases. This is the first case with radiopaque calcified nodules in the ligamenta flava causing spinal cord compression, the composition of which proved to be CPPD. PMID:6243349

  6. Crystallization characteristics of ammonium uranyl carbonate (AUC) in ammonium carbonate solutions

    NASA Astrophysics Data System (ADS)

    Tae-Joon, Kim; Kyung-Chai, Jeong; Jin-Ho, Park; In-Soon, Chang; Cheong-Song, Choi

    1994-05-01

    Ammonium carbonate solutions with an excessive amount of NH 3 were produced in a commercial AUC (ammonium uranyl carbonate) conversion plant. In this study the AUC crystals, precipitated with uranyl nitrate and ammonium carbonate solutions prepared in the laboratory, were characterized to determine the feasibility of recycling ammonium carbonate solution. The AUC crystals were easily agglomerated with the increasing concentration of CO 32- and mole ratio of {NH 4+}/{CO 32-} in ammonium carbonate solution. Effects of a mixing system for the solution in the AUC crystallizer and the feed location of the solution on the agglomeration of AUC crystals were also studied along with the effects of agglomerated AUC powders on UO 2 powders. Finally, the feasibility of manufacturing UO 2 fuel with a sintered pellet density of 10.52 g/cm 3, using the AUC powders generated in this experiment, was demonstrated.

  7. Study on the Functionality of Nano-Precipitated Calcium Carbonate as Filler in Thermoplastics

    Microsoft Academic Search

    Blessie A. Basilia; Marian Elaine G. Panganiban; Archilles Allen V. C. Collado; Michael Oliver D. Pesigan; Persia Ada de Yro

    2007-01-01

    This research aims to investigate the functionality of nano-precipitated calcium carbonate (NPCC) as filler in thermoplastic resins based on property enhancement. Three types of thermoplastics were used: polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC). The resins were evaluated by determining the effect of different NPCC loading on the chemical structure, thermal and mechanical properties of thermoplastics. Results showed that

  8. The Interactions of Silane and Zirconate Coupling Agents with Calcium Carbonate

    Microsoft Academic Search

    R. Doufnoune; N. Haddaoui; F. Riahi

    2007-01-01

    The present work deals with the study of the structure and the form of the deposit on calcium carbonate of two types of silane coupling agents and a zirconate one. The structure of the deposited layers as well as their interactions with the filler were investigated by means of Fourier Transform Infra-Red Spectroscopy. The extent of the recovery was determined

  9. Adsorption of polyoxyethylene alkyl-phenols onto calcium carbonate from aqueous solution

    Microsoft Academic Search

    R. J. Akers; P. M. Riley

    1974-01-01

    The adsorption of polyoxyethylene alkyl-phenols onto calcium carbonate has previously been reported by Kuno and Abe. A similar series of experiments has been conducted and substantilly different results obtained. The data are summarized in tabular form. The surface areas covered per molecule are calculated on the basis of the mean molecular weight and the nitrogen adsorption BET isotherm for the

  10. High surface area calcium carbonate: Pore structural properties and sulfation characteristics

    Microsoft Academic Search

    S.-H. Wei; S. K. Mahuli; R. Agnihotri; L.-S. Fan

    1997-01-01

    Limestone or calcium carbonate (CaCOâ) used as a sorbent in the removal of acid gas precursors (SOâ) from combustion systems suffers from poor pore structural properties which causes low reactivity and incomplete utilization. The surface area and pore size distribution of CaCOâ, if tailored appropriately, can considerably enhance its reactivity for SOâ. This study focuses on the optimization of pore

  11. PRELIMINARY RESULTS OF A STUDY OF CALCIUM CARBONATE SATURATION OF GROUND WATER IN CENTRAL FLORIDA

    Microsoft Academic Search

    William BACK

    1963-01-01

    The departure of ground water from equilibrium with calcite is being studied in central Florida. Measurements of pH, temperature, and concentration of bicarbonate made in the field are used with standard laboratory analyses of water samples to calculate an ion activity product (Kiap) for calcium carbonate. The calculated Kiap is compared with the equilibrium constant (Keq) for calcite to determine

  12. ?-wollastonite reinforced glass-ceramics prepared from waste fluorescent glass and calcium carbonate

    Microsoft Academic Search

    Yeon-Hum Yun; Sang-Bok Kim; Bo-An Kang; Young-Whan Lee; Jeong-Sun Oh; Kyu-Seog Hwang

    2006-01-01

    We prepared glass-ceramics reinforced by ?-wollastonite using waste fluorescent glass to resolve the environmental problem. Fluorescent glass and calcium carbonate were used as starting materials. The chemical durability of specimens heat treated at 800, 900 and 1000°C was analyzed by both the measurement of weight change, and observation of surface morphology. The composition of the specimens was determined with energy

  13. A transparent hybrid of nanocrystalline cellulose and amorphous calcium carbonate nanoparticles

    Microsoft Academic Search

    Denis Gebauer; Vitaliy Oliynyk; Michaela Salajkova; Jordi Sort; Qi Zhou; Lennart Bergström; German Salazar-Alvarez

    2011-01-01

    Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids of nanocrystalline cellulose (NCC) and amorphous calcium carbonate (ACC) nanoparticles were obtained through a facile chemical approach over a wide range of compositions. Controlling the interactions between NCC and ACC results in hard, transparent structures with tunable composition, homogeneity and anisotropy.Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids

  14. Trichomes of Tobacco Excrete Zinc as Zinc-Substituted Calcium Carbonate and Other

    E-print Network

    to study biomineralization and metal homeostasis processes in plants. Smoking of tobacco (Nicotiana tabacumTrichomes of Tobacco Excrete Zinc as Zinc-Substituted Calcium Carbonate and Other Zinc.F., M.A.M.) Tobacco (Nicotiana tabacum L. cv Xanthi) plants were exposed to toxic levels of zinc (Zn

  15. Effect of calcium carbonate and aluminum hydroxide on human intestinal function

    Microsoft Academic Search

    David Saunders; Jim Sillery; Roger Chapman

    1988-01-01

    The effect of calcium carbonate (6 g daily) and of aluminum hydroxide (Amphojel, 7.2 g daily) on human gastrointestinal function was examined because these popular antacids have a documented effect on fecal fat, an undocumented association with constipation, and a putative ability to ameliorate cocarcinogenic effects of bile acids and fatty acids on colonic mucosa. Intake-output studies were conducted over

  16. PROGRESS REPORT. THE INFLUENCE OF CALCIUM CARBONATE GRAIN COATINGS ON CONTAMINANT REACTIVITY IN VADOSE ZONE SEDIMENTS

    EPA Science Inventory

    This project explores the behavior of calcium carbonate grain coatings, including how they form and dissolve, their reactivity toward key Hanford contaminants, their impact (as surface coatings) on the reactivity of other mineral substrates, and on their in-ground composition and...

  17. EXPERIMENTAL DETERMINATION OF THE CALCIUM CARBONATE SATURATION STATES OF WATER SYSTEMS (TECHNICAL NOTE)

    EPA Science Inventory

    Emphasis is given to the fact that saturation indexes only indicate the tendency of a water to dissolve or precipitate calcium carbonate (CaCo3). The rate at which a given water attains equilibrium cannot be derived from the saturation index value....

  18. Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef

    Microsoft Academic Search

    Chris Langdon; Taro Takahashi; Colm Sweeney; Dave Chipman; John Goddard; Francesca Marubini; Heather Aceves; Heidi Barnett; Marlin J. Atkinson

    2000-01-01

    The concentration of CO2 in the atmosphere is projected to reach twice the preindustrial level by the middle of the 21st century. This increase will reduce the concentration of CO32- of the surface ocean by 30% relative to the preindustrial level and will reduce the calcium carbonate saturation state of the surface ocean by an equal percentage. Using the large

  19. ANNUAL REPORT. THE INFLUENCE OF CALCIUM CARBONATE GRAIN COATINGS ON CONTAMINANT REACTIVITY IN VADOSE ZONE SEDIMENTS

    EPA Science Inventory

    The primary objective of this project is to investigate the role of calcium carbonate grain coatings on adsorption and heterogeneous reduction reactions of key chemical and radioactive contaminants in sediments on the Hanford Site. Research will ascertain whether these coatings p...

  20. A Laboratory Investigation of the Heterogeneous Reaction of Nitric Acid with Calcium Carbonate

    Microsoft Academic Search

    V. H. Grassian; B. J. Krueger; A. Preszler Prince; M. A. Young

    2002-01-01

    Recent laboratory experiments on the heterogeneous reaction of nitric acid with calcium carbonate particles will be presented. Several different techniques are used to investigate and quantify morphology changes that occur during reaction, phase transformations, and the rate dependence of individual particles as a function of relative humidity. In addition, competitive reactions of other trace gases such as sulfur dioxide with

  1. 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. PMID:21458575

  2. Calcium oxalate crystals in fetal bovine serum: implications for cell culture, phagocytosis and biomineralization studies in vitro.

    PubMed

    Pedraza, Claudio E; Chien, Yung-Ching; McKee, Marc D

    2008-04-01

    Cell culture methods and models are key investigative tools for cell and molecular biology studies. Fetal bovine serum (FBS) is commonly used as an additive during cell culture since its constituents promote cell survival, proliferation and differentiation. Here we report that commercially available FBS from different major suppliers consistently contain precipitated, calcium oxalate crystals-either in the monohydrate (COM) or dihydrate (COD) form. Mineral structure and phase identification of the crystals were determined by X-ray diffraction, chemical composition by energy-dispersive X-ray microanalysis, and imaging and measurement of crystal growth steps by atomic force microscopy-all identified and confirmed crystallographic parameters for COM and COD. Proteins binding to the crystals were identified by immunoblotting, revealing the presence of osteopontin and fetuin-A (alpha(2)HS-glycoprotein)--known regulators of crystal growth found in serum. Macrophage cell cultures exposed to calcium oxalate crystals showed internalization of the crystals by phagocytosis in a process that induced disruption of cell-cell adhesion, release of reactive oxygen species and membrane damage, events that may be linked to the release of inflammatory cytokines by these cells into the culture media. In conclusion, calcium oxalate crystals found in commercially available FBS are toxic to cells, and their presence may confound results from in vitro studies where, amongst others, phagocytosis, biomineralization, renal cell and molecular biology, and drug and biomaterial testing are being examined. PMID:17879965

  3. Hot alkali carbonation of sodium metaphosphate modified fly ash/calcium aluminate blend hydrothermal cements

    SciTech Connect

    Sugama, T. [Brookhaven National Lab., Upton, NY (United States). Energy Efficiency and Conservation Div.] [Brookhaven National Lab., Upton, NY (United States). Energy Efficiency and Conservation Div.

    1996-11-01

    Sodium metaphosphate-modified fly ash/calcium aluminate blend (SFCB) cements were prepared by autoclaving for 1 day at 300 C and their resistance was evaluated in a highly concentrated Na{sub 2}CO{sub 3} solution at 300 C. The hydroxyapatite and analcime phases formed in the autoclaved SFCB cements played an essential role in conferring resistance to the degradation of cements caused by alkali carbonation. Although the carbonating reaction of the analcime phase led to the formation of cancrinite, this analcime cancrinite transformation did not show any influence on the changes in the mechanical and physical properties of the cements. Additionally, there was no formation of the water-soluble calcium bicarbonate in the cements exposed for 28 days. Contrarily, the conventional class G cement systems were very vulnerable to a hot alkali carbonation. The major reason for the damage caused by carbonation of the cements was the fact that the xonotlite phase formed in the 300{degree} autoclaved cements was converted into two carbonation products, calcite and pectolite. Furthermore, the reaction between calcite and carbonic acid derived from Na{sub 2}CO{sub 3} led to the formation of water-soluble calcium bicarbonate, thereby causing the alteration of dense structures into porous ones and the loss of strength of cements.

  4. Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

    PubMed Central

    Knowles, Jonathan C; Rehman, Ihtesham; Darr, Jawwad A

    2013-01-01

    A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO3-HA) with ?5?wt% substituted carbonate content (sample 7.5CO3-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO3-HA. For silicate-substituted hydroxyapatite (SiO4-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ?1.1?wt% exists for synthesis of SiO4-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy. PMID:22983020

  5. [Chemical structure of dicarboxylic acids and their capacity inhibiting of calcium oxalate crystal growth].

    PubMed

    Deng, Sui-ping; Hu, Peng; Ouyang, Jian-ming

    2007-10-01

    The effect of dicarboxylic acids with a three C-C bonds distance on the crystallization of calcium oxalate (CaOxa) was investigated in silica gel system by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). These acids include succinic acid, maleic acid, fumaric acid, malic acid, L-aspartic acid and tartaric acid. All the dicarboxylic acids can inhibit the aggregation of calcium oxalate monohydrate (COM) and induce the formation of calcium oxalate dehydrate (COD). But their ability to inhibit the growth and aggregation of COM, to diminish the specific surface area of COM and to induce COD formation were strengthened as the number of the substituted hydroxyl or amino group increased. The molecular mechanisms were discussed in terms of chemical structures of dicarboxylic acids. Only the dicarboxylic acids with a HOOC-CH(R)-CH2-COOH (R=OH or NH2) group were found to have the best inhibitory effect on the CaOxa urinary stones. The results could provide some clue to looking for new drugs for urinary stones in clinic. PMID:18306777

  6. Evidence for Calcium Carbonate at the Phoenix Landing Site

    NASA Technical Reports Server (NTRS)

    Boynton, W. V.; Ming, D. W.; Sutter, B.; Arvidson, R. E.; Hoffman, J.; Niles, P. B.; Smith, P.

    2009-01-01

    The Phoenix mission has recently finished its study of the north polar environment of Mars with the aim to help understand both the current climate and to put constraints on past climate. An important part of understanding the past climate is the study of secondary minerals, those formed by reaction with volatile compounds such as H2O and CO2. This work describes observations made by the Thermal and Evolved-Gas Analyzer (TEGA) on the Phoenix Lander related to carbonate minerals. Carbonates are generally considered to be products of aqueous processes. A wet and warmer climate during the early history of Mars coupled with a much denser CO2 atmosphere are ideal conditions for the aqueous alteration of basaltic materials and the subsequent formation of carbonates. Carbonates (Mg- and Ca-rich) are predicted to be thermodynamically stable minerals in the present martian environment, however, there have been only a few indications of carbonates on the surface by a host of orbiting and landed missions to Mars. Carbonates (Mg-rich) have been suggested to be a component (2-5 wt %) of the martian global dust based upon orbital thermal emission spectroscopy. The identifications, based on the presence of a 1480 cm-1 absorption feature, are consistent with Mgcarbonates. A similar feature is observed in brighter, undisturbed soils by Mini-TES on the Gusev plains. Recently, Mg-rich carbonates have been identified in the Nili Fossae region by the CRISM instrument onboard the Mars Reconnaissance Orbiter. Carbonates have also been confirmed as aqueous alteration phases in martian meteorites so it is puzzling why there have not been more discoveries of carbonates by landers, rovers, and orbiters. Carbonates may hold important clues about the history of liquid water and aqueous processes on the surface of Mars.

  7. Effect of calcium carbonate on the compliance of an apatitic calcium phosphate bone cement.

    PubMed

    Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

    1997-12-01

    Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing alpha-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to Biocement H, whereas Biocement B1 was made by adding some CaCO3 but with simultaneous adjustment of the amount of precipitated hydroxyapatite.The liquid/ powder ratio of the cement paste and the accelerator concentrations (percentage Na2HPO4) in cement liquid were varied. For Biocement H there was no combination of L/P ratio and percentage Na2HPO4 for which all clinical requirements were satisfied. However, there was an area of full compliance for Biocements B1 and B2, of which that for B1 was the largest. Therefore, Biocement B1 may be applied in clinical situations as those in orthopaedics, plastic and reconstructive surgery and oral and maxillofacial surgery, even when early contact with blood is inevitable. PMID:9430336

  8. Investigation of self-frequency doubling crystals, yttrium calcium oxyborate (YCOB), doped with neodymium or ytterbium

    NASA Astrophysics Data System (ADS)

    Ye, Qing

    1999-09-01

    There is a need for low cost red, green, and blue (RGB) lasers for a number of commercial applications such as high-resolution laser printing, full color laser display. While semiconductor lasers still have both availability (green and blue) and beam quality (red) problems, nonlinear frequency conversion of diode-pumped solid state lasers are good alternatives. Among them, self- frequency doubling is an attractive approach because of its simpler design and lower cost. Unfortunately, few known crystals possess self-frequency doubling property. A newly discovered yttrium calcium oxyborate (YCOB) can fill in the role because it has adequate lasing and nonlinear frequency conversion efficiency. More importantly, YCOB crystal melts congruently so that high quality, large size single crystals can be grown using conventional Czochralski melt pulling technique. The thermal mechanical properties, linear and nonlinear optical properties of YCOB, laser properties of Nd:YCOB and Yb:YCOB crystals were investigated. Based on the calculated second harmonic phase matching angles, Nd:YCOB laser rods were fabricated. Self-frequency doubled green emission with 62 mW output power and red emission with 16 mW output power were successfully demonstrated using diode-pumping. It is the first time to achieve the continuous wave (cw) red lasing in Nd doped rare-earth calcium oxyborates. Rare-earth ions doping in YCOB crystal can not only achieve lasing, but also affect the physical and chemical properties of the crystal. The stability field of YCOB is reduced in proportion to both the ionic size differences from yttrium and doping concentrations of the rare-earth ions. The doping also changes the linear and nonlinear optical properties of the material. For example, the second harmonic conversion efficiency of 20% Yb doped YCOB was enhanced by more than 15% compared to undoped YCOB. The absorption cutoff edge of 20% Yb:YCOB was red- shift by more than 60 nm. Similar effects were observed in Ce, or Pr, or Eu doped YCOB crystals. It is proposed that the rare-earth ions with variable oxidation states can serve as either donor or acceptor to the conjugated ?-orbits formed by the (BO3)3- planar groups in the YCOB structure to increase the delocalization of electron clouds, and thus increase the nonlinearity and result in the red-shift of the energy band-gap. In summary, the YCOB is the first nonhygroscopic nonlinear crystal with high damage threshold that can provide both large aperture and long nonlinear conversion length for high power laser applications. The Nd:YCOB shows promising features as a diode-pumped self-frequency doubling laser material to generate efficient, compact, low cost cw red and green emissions. Investigation of the whole rare-earth calcium oxyborate family compounds is just at the early stage. It is expected that these crystals would have a great impact on nonlinear optical device market in the very near future.

  9. Effects of Sevelamer Hydrochloride and Calcium Carbonate on Renal Osteodystrophy in Hemodialysis Patients

    PubMed Central

    Ferreira, Aníbal; Frazão, João Miguel; Monier-Faugere, Marie-Claude; Gil, Célia; Galvao, José; Oliveira, Carlos; Baldaia, Jorge; Rodrigues, Ilidio; Santos, Carla; Ribeiro, Silvia; Hoenger, Regula Mueller; Duggal, Ajay; Malluche, Hartmut H.

    2008-01-01

    Disturbances in mineral metabolism play a central role in the development of renal bone disease. In a 54-wk, randomized, open-label study, 119 hemodialysis patients were enrolled to compare the effects of sevelamer hydrochloride and calcium carbonate on bone. Biopsy-proven adynamic bone disease was the most frequent bone abnormality at baseline (59%). Serum phosphorus, calcium, and intact parathyroid hormone were well controlled in both groups, although calcium was consistently lower and intact parathyroid hormone higher among patients who were randomly assigned to sevelamer. Compared with baseline values, there were no changes in mineralization lag time or measures of bone turnover (e.g., activation frequency) after 1 yr in either group. Osteoid thickness significantly increased in both groups, but there was no significant difference between them. Bone formation rate per bone surface, however, significantly increased from baseline only in the sevelamer group (P = 0.019). In addition, of those with abnormal microarchitecture at baseline (i.e., trabecular separation), seven of 10 in the sevelamer group normalized after 1 yr compared with zero of three in the calcium group. In summary, sevelamer resulted in no statistically significant changes in bone turnover or mineralization compared with calcium carbonate, but bone formation increased and trabecular architecture improved with sevelamer. Further studies are required to assess whether these changes affect clinical outcomes, such as rates of fracture. PMID:18199805

  10. 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.

  11. The Properties and Characteristics of Concretes Containing Calcium Carbonate (CaCO3) and Synthetic Lightweight Aggregate

    NASA Astrophysics Data System (ADS)

    Ramos, Matthew J.

    The purpose of this study was to investigate the efficacy of precipitated calcium carbonate as a means for enhancing the mechanical and environmental favorability of concretes containing synthetic lightweight aggregates (SLA), which are comprised of recycled mixed plastic and fly ash. Compressive strength tests show that 2% calcium carbonate additions are able to mitigate strength decreases induced by SLA as well as decrease concrete density when compared to NWA concretes. SLA concretes containing 5% calcium carbonate do not show the same trend. Instead, strength decreases and density increases are observed. Furthermore, increases in aluminum trisulphate (AFt) phase mineralization are observed through scanning electron microscopy. Results suggest that calcium carbonate additions increase early hydration and stabilize AFt minerals thaumasite and ettringite throughout hydration. It is proposed that increased AFt phase mineralization causes reductions in concrete density. However, a limit to this relationship was observed as additions of greater than 2% calcium carbonate exceed the potential for increased hydration, causing a threshold effect that resulted in calcium carbonate acting as filler, which increases density. Improved mechanical properties and the ability to stabilize waste plastics, fly ash, and CO2 emissions make the use of 2% calcium carbonate in conjunction with SLA a favorable alternative to ordinary concretes.

  12. Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs

    PubMed Central

    Sekkal, W.; Zaoui, A.

    2013-01-01

    Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99?J/m2) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2?J/m2, i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images. PMID:23545842

  13. Sodium and carbonate distribution in substituted calcium hydroxyapatite

    Microsoft Academic Search

    Hafed El Feki; Jean Michel Savariault; Abdelhamid Ben Salah; Mohamed Jemal

    2000-01-01

    Hydroxyapatites containing sodium and carbonate are prepared according to a double decomposition method. Two samples have been investigated by IR absorption spectroscopy and X-ray powder pattern fitting methods. Results confirm that both compounds pertain to the apatite family crystallising in a hexagonal system, space group P63\\/m. The cell parameters of the lower carbonate content apatite are a=9.3892(4) and c=6.9019(3) Å,

  14. In situ calcium carbonate dissolution in the Pacific Ocean

    Microsoft Academic Search

    R. A. Feely; Chris Sabine; K. Lee; F. J. Millero; M. F. Lamb; D. Greeley; J. L. Bullister; Robert Key; T.-H. Peng; Alexander Kozyr; Tsueno Ono; C. S. Wong

    2002-01-01

    Over the past several years researchers have been working to synthesize the WOCE\\/JGOFS global CO2 survey data to better understand carbon cycling processes in the oceans. The Pacific Ocean data set has over 35,000 sample locations with at least two carbon parameters, oxygen, nutrients, CFC tracers, and hydrographic parameters. In this paper we estimate the in situ CaCO3 dissolution rates

  15. Optical Study of Liquid Crystal Doped with Multiwalled Carbon Nanotube

    NASA Astrophysics Data System (ADS)

    Gharde, Rita A.; Thakare, Sangeeta Y.

    2014-11-01

    Liquid crystalline materials have been useful for display devices i.e watches, calculators, automobile dashboards, televisions, multi media projectors etc. as well as in electro tunable lasers, optical fibers and lenses. Carbon nanotube is chosen as the main experimental factor in this study as it has been observed that Carbon Nano Tube influence the existing properties of liquid crystal host and with the doping of CNT can enhance1 the properties of LC. The combination of carbon nanotube (CNT) and liquid crystal (LC) materials show considerable interest in the scientific community due to unique physical properties of CNT in liquid crystal. Dispersion of CNTs in LCs can provide us a cheap, simple, versatile and effective means of controlling nanotube orientation on macroscopic scale with no restrictions on nanotube type. LCs have the long range orientational order rendering them to be anisotropic phases. If CNTs can be well dispersed in LC matrix, they will align with their long axes along the LC director to minimize distortions of the LC director field and the free energy. In this paper, we doped liquid crystal (Cholesteryl Nonanoate) by a small amount of multiwall carbon nanotube 0.05% and 0.1% wt. We found that by adding carbon nanotube to liquid crystals the melting point of the mixture is decreased but TNI is increased. It has been also observed that with incereas in concentration of carbon nanotube into liquid crystal shows conciderable effect on LC. The prepared samples were characterized using various techniques to study structural, thermal and optical properties i.e PMS, FPSS, UV-Vis spectroscopy, FT-IR measurements, and DTA.

  16. Antioxidant Properties of Polysaccharide from the Brown Seaweed Sargassum graminifolium (Turn.), and Its Effects on Calcium Oxalate Crystallization

    PubMed Central

    Zhang, Chao-Yan; Wu, Wen-Hui; Wang, Jue; Lan, Min-Bo

    2012-01-01

    We investigated the effects of polysaccharides from the brown seaweed Sargassum graminifolium (Turn.) (SGP) on calcium oxalate crystallization, and determined its antioxidant activities. To examine the effects of SGP on calcium oxalate crystallization, we monitored nucleation and aggregation of calcium oxalate monohydrate crystals, using trisodium citrate as a positive control. We assessed antioxidant activities of SGP by determining its reducing power, its ability to scavenge superoxide radicals, and its activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The nucleation inhibition ratio of trisodium citrate and SGP was 58.5 and 69.2%, respectively, and crystal aggregation was inhibited by 71.4 and 76.8%, respectively. Increasing concentrations of SGP resulted in increased scavenging of superoxide anions and DPPH radicals (IC50 = 1.9 and 0.6 mg/mL, respectively). These results suggest that SGP could be a candidate for treating urinary stones because of its ability to inhibit calcium oxalate crystallization and its antioxidant properties. PMID:22363225

  17. Oxygen isotope fractionation during the dolomitization of calcium carbonate

    Microsoft Academic Search

    Alan Matthews; Amitai Katz

    1977-01-01

    The oxygen isotope fractionation accompanying the hydrothermal dolomitization of CaCO 3 between 252 and 295°C has been investigated. Dolomitization (which occurs via the crystallization of one or more intermediate magnesian calcite phases) is characterised by a progressive lowering in 8 O , which smoothly correlates with the change in the Mg\\/(Mg + Ca) and the Sr \\/( Mg + Ca

  18. Crystallization behavior of silica-calcium phosphate biocomposites: XRD and FTIR studies.

    PubMed

    Ning, C Q; Greish, Y; El-Ghannam, A

    2004-11-01

    Silica and calcium phosphates (CaP) are the most important ingredients in bioactive materials that bond to bone and enhance bone tissue formation. In this study, silica-calcium phosphate (SiO2-CaP) composites were developed by powder metallurgy method, using silica (SiO2) and anhydrous dicalcium phosphate (CaHPO4) powders (CaP) in the ratios (wt%): 20/80, 40/60, 60/40 and 80/20. The effects of temperature and chemical composition on crystallization and phase transformation of the SiO2-CaP composites were evaluated by XRD and FTIR. Thermal treatment of the starting material suggested that CaHPO4 transforms into: gamma-Ca2P2O7 at 800 degrees C; beta-Ca2P2O7 at 1000 degrees C and alpha-Ca2P2O7 at 1200 degrees C. On the other hand, beta-quartz was the only detected phase after thermal treatment of silica in the temperature range 800-1200 degrees C. For all SiO2-CaP composites, SiO2 and CaP did not modify the crystallization behavior of each other when sintered in the temperature range 800-1000 degrees C. However, at 1200 degrees C, CaP promoted the transformation of gamma-quartz into alpha-cristobalite. Moreover, SiO2 stabilized beta-Ca2P2O7. The modifications in the crystallization behavior were related to ion substitution and formation of solid solutions. PMID:15880933

  19. Synthesis of sodium caseinate-calcium carbonate microspheres and their mineralization to bone-like apatite

    NASA Astrophysics Data System (ADS)

    Xu, Zhewu; Liang, Guobin; Jin, Lin; Wang, Zhenling; Xing, Chao; Jiange, Qing; Zhang, Zhiguang

    2014-06-01

    Phosphoproteins can induce and stabilize calcium carbonate (CaCO3) vaterite, which has desirable features for high reactivity. The purpose of this study was to synthesize bioactive CaCO3 microspheres for bone regeneration. Sodium caseinate (NaCas)-containing CaCO3 microspheres, with the crystal phase of vaterite, were synthesized by fast precipitation in an aqueous solution of CaCl2, Na2CO3, and 2 mg/mL of NaCas. The uniform microspheres exhibited rougher surfaces and lower negative charges than CaCO3 particles without NaCas addition. Fourier-transform infrared spectroscopy (FT-IR) of the microspheres showed characteristic peaks or bands corresponding to phosphate and hydroxyl groups. Thermogravimetric analysis (TGA) curves exhibited approximately 5% weight loss below 600 °C due to the decomposition of NaCas. Scanning electron microscope (SEM) images showed lath-like hydroxyapatite (HAp) on the surface after soaking in simulated body fluid (SBF) at 37 °C for 5 and 10 days. Energy dispersive X-ray spectrometry (EDS) revealed that the agglomerates were composed of Ca, C, O, P, Na, and Mg elements, and the Ca/P ratios ranged from 1.53 to 1.56. X-ray diffraction (XRD) patterns exhibited peaks characteristic of hydroxyapatite. The results of this study demonstrated that the addition of NaCas induced the formation of vaterite microspheres which possesses an enhanced apatite formation after soaking in SBF at 37 °C for 5 and 10 days. These NaCas-CaCO3 microspheres may be a potential biomaterial for bone regeneration.

  20. Density functional theory for carbon dioxide crystal

    SciTech Connect

    Chang, Yiwen; Mi, Jianguo, E-mail: mijg@mail.buct.edu.cn; Zhong, Chongli [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)

    2014-05-28

    We present a density functional approach to describe the solid?liquid phase transition, interfacial and crystal structure, and properties of polyatomic CO{sub 2}. Unlike previous phase field crystal model or density functional theory, which are derived from the second order direct correlation function, the present density functional approach is based on the fundamental measure theory for hard-sphere repulsion in solid. More importantly, the contributions of enthalpic interactions due to the dispersive attractions and of entropic interactions arising from the molecular architecture are integrated in the density functional model. Using the theoretical model, the predicted liquid and solid densities of CO{sub 2} at equilibrium triple point are in good agreement with the experimental values. Based on the structure of crystal-liquid interfaces in different planes, the corresponding interfacial tensions are predicted. Their respective accuracies need to be tested.

  1. Physical properties of cholesteric liquid crystals - carbon nanotube dispersions

    NASA Astrophysics Data System (ADS)

    Usol'tseva, N. V.; Smirnova, M. V.; Sotsky, V. V.; Smirnova, A. I.

    2014-12-01

    The mesomorphic and visco-elastic properties of cholesteric liquid crystal - multiwall carbon nanotube dispersions were investigated with respect to temperature and nanotube concentration. The important rheology characteristics, such as dynamic viscosity, elastic modulus and loss modulus were studied. For the first time a 3D-model of cholesteric liquid crystal at the temperature of cholesteric phase existence was obtained by molecular dynamics simulation method. A weak effect of nanotube on the molecular orientation of the liquid crystal molecules in the N* phase was found.

  2. All three Ca[superscript 2+]-binding loops of photoproteins bind calcium ions: The crystal structures of calcium-loaded apo-aequorin and apo-obelin

    SciTech Connect

    Deng, Lu; Vysotski, Eugene S.; Markova, Svetlana V.; Liu, Zhi-Jie; Lee, John; Rose, John; Wang, Bi-Cheng (Georgia)

    2010-07-13

    The crystal structures of calcium-loaded apoaequorin and apo-obelin have been determined at resolutions 1.7 {angstrom} and 2.2 {angstrom}, respectively. A calcium ion is observed in each of the three EF-hand loops that have the canonical calcium-binding sequence, and each is coordinated in the characteristic pentagonal bipyramidal configuration. The calcium-loaded apo-proteins retain the same compact scaffold and overall fold as the unreacted photoproteins containing the bound substrate, 2-hydroperoxycoelenterazine, and also the same as the Ca{sup 2+}-discharged obelin bound with the product, coelenteramide. Nevertheless, there are easily discerned shifts in both helix and loop regions, and the shifts are not the same between the two proteins. It is suggested that these subtle shifts are the basis of the ability of these photoproteins to sense Ca{sup 2+} concentration transients and to produce their bioluminescence response on the millisecond timescale. A mechanism of intrastructural transmission of the calcium signal is proposed.

  3. Investigating the Role of Carbonate Ion Concentration on the Magnesium Content of Amorphous Calcium Carbonate

    NASA Astrophysics Data System (ADS)

    Blue, C.; Dove, P. M.; Han, N.

    2011-12-01

    The fields of biomineralization and carbonate geochemistry are undergoing a paradigm shift with the realization that the formation of calcite with diverse compositions and textures can be understood within the framework of multiple pathways to mineralization. Many organisms do not form their skeletons via the classical step-growth process, but instead mineralization occurs through a mesocrystal pathway that begins with the formation of amorphous calcium carbonate (ACC), which subsequently transforms to calcite. Little is known about factors that regulate this type of calcification because the last 50 years of research have focused almost entirely on step-growth processes. In particular, new findings indicate that the chemical signatures and properties of calcites that form via an amorphous pathway are significantly different. Variable temperature has been shown to influence the amount of magnesium that is incorporated into ACC, but the effect of alkalinity has not been constrained. Here, a flow-through method was developed to produce ACC within a geochemically relevant pH range and with a constant supersaturation, and to determine the effect of carbonate ion concentration on magnesium uptake. The experimental approach uses a high precision syringe pump to prepare ACC under specified and constant chemical conditions. This study used two syringes that contained: 1) 100 ml of MgCl2?6H2O and CaCl2?2H2O such that the Mg/Ca ratio is fixed at 5:1 (modern seawater), and 2) 100 ml of 60mM - 400mM NaHCO3. The initial sodium bicarbonate solutions were buffered to a pH of 9.75 using NaOH, and upon mixing with the 5:1 Mg/Ca solution the resulting pH range was 9.2 - 9.7. All experiments were performed at temperatures between 21.5 and 23 degrees Celsius. Solution and solids were collected on 0.20 micron filter paper with a vacuum pump running continuously. Experiments were typically conducted for an hour and a half and all samples were rinsed with distilled deionized water before collection. The final ACC samples were characterized using a combination of SEM, Raman Spectroscopy, and ICP-OES. Preliminary results indicate that the Mg content of ACC increases with the carbonate ion concentration of the input solution. This shift in composition corresponds with measurements of a smaller average particle size. Future work will determine if the ACC that forms at these different carbonate concentrations subsequently influences the composition and structure of the final crystalline products. Findings from this work may lead to better predictions of how biological calcification processes will respond to the shifts in carbonate chemistry that accompany ocean acidification.

  4. Control of calcium oxalate crystal growth by face-specific adsorption of an osteopontin phosphopeptide.

    PubMed

    Grohe, Bernd; O'Young, Jason; Ionescu, D Andrei; Lajoie, Gilles; Rogers, Kem A; Karttunen, Mikko; Goldberg, Harvey A; Hunter, Graeme K

    2007-12-01

    Mineral-associated proteins have been proposed to regulate many aspects of biomineralization, including the location, type, orientation, shape, and texture of crystals. To understand how proteins achieve this exquisite level of control, we are studying the interaction between the phosphoprotein osteopontin (OPN) and the biomineral calcium oxalate monohydrate (COM). In the present study, we have synthesized peptides corresponding to amino acids 220-235 of rat bone OPN (pSHEpSTEQSDAIDpSAEK), one of several highly phosphorylated, aspartic-, and glutamic acid-rich sequences found in the protein. To investigate the role of phosphorylation in interaction with crystals, peptides containing no (P0), one (P1), or all three (P3) phosphates were prepared. Using a novel combination of confocal microscopy and scanning electron microscopy, we show that these peptides adsorb preferentially to {100} faces of COM and inhibit growth of these faces in a phosphorylation-dependent manner. To characterize the mechanism of adsorption of OPN peptides to COM, we have performed the first atomic-scale molecular-dynamics simulation of a protein-crystal interaction. P3 adsorbs to the {100} face much more rapidly than P1, which in turn adsorbs more rapidly than P0. In all cases, aspartic and glutamic acid, not phosphoserine, are the amino acids in closest contact with the crystal surface. These studies have identified a COM face-specific adsorption motif in OPN and delineated separate roles for carboxylate and phosphate groups in inhibition of crystal growth by mineral-associated phosphoproteins. We propose that the formation of close-range, stable, and face-specific interactions is a key factor in the ability of phosphoproteins to regulate biomineralization processes. PMID:17994739

  5. EFFECTS OF SODIUM AND CALCIUM IN LIGNITE ON THE PERFORMANCE OF ACTIVATED CARBON PRODUCTS

    SciTech Connect

    Edwin S. Olson; Kurt E. Eylands; Daniel J. Stepan

    2001-12-01

    Powdered activated carbon (PAC) has traditionally been used by the water treatment industry for the removal of compounds contributing to taste and odor problems. PAC also has the potential to remove naturally occurring organic matter (NOM) from raw waters prior to disinfection, thus controlling the formation of regulated disinfection by-products (DBPs). Many small water systems are currently using PAC for taste and odor control and have the potential to use PAC for controlling DBPs. The Energy & Environmental Research Center has been working on the development of a PAC product to remove NOM from surface water supplies to prevent the formation of carcinogenic DBPs during chlorination. During previous studies, the sodium and calcium content of the lignites showed a significant effect on the sorption capacity of the activated carbon product. As much as a 130% increase in the humic acid sorption capacity of a PAC produced from a high-sodium-content lignite was observed. During this study, activated carbons were prepared from three coals representing high-sodium, low-sodium--low-calcium, and high-calcium compositions in two steps, an initial char formation followed by mild activation with steam to avoid excessive burnout. This set of carbons was characterized with respect to physical and chemical properties. The BET (Brunauer-Emmett-Teller) nitrogen adsorption isotherms gave relatively low surface areas (ranging from 245 to 370 m{sup 2}/g). The lowest-BET area was obtained for the high-sodium carbon, which can be attributed to enlargement of micropores as a result of sodium-catalyzed gasification reaction of the carbon structure. This hypothesis is consistent with the scanning electron microscopy microprobe analyses, which show that in both the coal and the activated carbon from this coal, the sodium is distributed over both the carbon structure and the mineral particles. Thus it is initially associated with carboxylate groups on the coal and then as sodium oxide or other active form in close proximity to the carbon and is, therefore, readily available for catalysis of gasification. Humate adsorption isotherms for the high-sodium carbon gave superior results as defined by very high intercepts in modified Freundlich plots. Thus the high-sodium carbon will be considerably more effective in reducing the humate concentration for a given carbon dosage. Analysis of adsorption isotherms indicated the results were consistent with the hypothesis that only the larger pores are effective for binding the large humate molecules, and that the larger pores developed during activation of the high-sodium char give the appropriate macropore structure for humate binding. Toluene adsorption isotherms indicated that the high-calcium carbon and the low-calcium, low-sodium carbon were superior to the high-sodium carbon for small molecules in aqueous solution, but not as effective as a Calgon F-400 commercial activated carbon. This is consistent with the low-BET surface areas observed for the lignite-derived carbons, and thus there are a lower number of sites for binding the smaller toluene molecule in these carbons.

  6. A geospatial assessment of the relationship between reef flat community calcium carbonate production and wave energy

    NASA Astrophysics Data System (ADS)

    Hamylton, S. M.; Pescud, A.; Leon, J. X.; Callaghan, D. P.

    2013-12-01

    The ability of benthic communities inhabiting coral reefs to produce calcium carbonate underpins the development of reef platforms and associated sedimentary landforms, as well as the fixation of inorganic carbon and buffering of diurnal pH fluctuations in ocean surface waters. Quantification of the relationship between reef flat community calcium carbonate production and wave energy provides an empirical basis for understanding and managing this functionally important process. This study employs geospatial techniques across the reef platform at Lizard Island, Great Barrier Reef, to (1) map the distribution and estimate the total magnitude of reef community carbonate production and (2) empirically ascertain the influence of wave energy on community carbonate production. A World-View-2 satellite image and a field data set of 364 ground referencing points are employed, along with data on physical reef characteristics (e.g. bathymetry, rugosity) to map and validate the spatial distribution of the four major community carbonate producers (live coral, carbonate sand, green calcareous macroalgae and encrusting calcified algae) across the reef platform. Carbonate production is estimated for the complete reef platform from the composition of these community components. A synoptic model of wave energy is developed using the Simulating WAves Nearshore (SWAN) two-dimensional model for the entire reef platform. The relationship between locally derived measures of carbonate production and wave energy is evaluated at both the global scale and local scale along spatial gradients of wave energy traversing the reef platform. A wave energy threshold is identified, below which carbonate production levels appear to increase with wave energy and above which mechanical forcing reduces community production. This implies an optimal set of hydrodynamic conditions characterized by wave energy levels of approximately 300 J m-2, providing an empirical basis for management of potential changes in community carbonate production associated with climate change-driven increases in wave energy.

  7. Interaction of Er{sup 3+} ions in Er-doped calcium - niobium - gallium garnet crystals

    SciTech Connect

    Malov, A V [N.P. Ogarev Mordovian State University, Saransk (Russian Federation); Popov, A V [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Ryabochkina, P A; Bol'shakov, E V

    2010-08-03

    The processes of nonradiative energy transfer in calcium - niobium - gallium garnet (CNGG) crystals doped with Er{sup 3+} ions are studied. It is found that the energy of erbium ions in the Er:CNGG crystal with the erbium atomic concentrations C{sub Er}=6% and 11% is transferred via the nonradiative co-operative processes {sup 4}I{sub 11/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 11/2{yields}} {sup 4}F{sub 7/2}, {sup 4}I{sub 11/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 13/2{yields}} {sup 4}F{sub 9/2}; and {sup 4}I{sub 13/2{yields}} {sup 4}I{sub 15/2}, {sup 4}I{sub 13/2{yields}} {sup 4}I{sub 9/2}, whose efficiency increases with increasing intensity of exciting radiation. It is shown that the cross-relaxation processes {sup 4}S{sub 3/2{yields}}{sup 4}I{sub 9/2}, {sup 4}I{sub 15/2{yields}}{sup 4}I{sub 13/2}, whose intensity depends on the concentration of Er{sup 3+} ions, are characteristic for Er:CNGG crystals with the Er atomic concentration above 1%. (active media)

  8. Calciphytoliths (calcium oxalate crystals) analysis for the identification of decayed tea plants (Camellia sinensis L.)

    PubMed Central

    Zhang, Jianping; Lu, Houyuan; Huang, Linpei

    2014-01-01

    The history of tea is poorly known, mainly due to the questionable identification of decayed tea plants in archaeological samples. This paper attempts to test the utility of calciphytoliths (calcium oxalate crystals) for the identification of tea in archaeological samples. It provides the first survey of the macropatterns of calciphytoliths in several species of Theaceae and common non-Theaceae plants. Crystals were extracted from 45 samples of tea, Theaceae and common non-Theaceae plants, and detected microscopically between crossed polarizers. In tea plants, druse and trichome base are the most distinctive crystals. Druses have the smallest diameter (11.65 ± 3.64??m), and trichome bases have four distinctive straight and regular cracks, similar to a regular extinction cross. The results provide morphological criteria for distinguishing tea from other plants, specifically the presence of identifiable druses together with calcified trichome bases. The implications are significant for understanding the history of tea and plant exploitation, especially for plants for which the preservation of macrofossils is poor. PMID:25342006

  9. UV-induced nonlinear absorption in lanthanum calcium borate single crystals.

    PubMed

    Kityk, I V; Majchrowski, A; Michalski, E; Kasprowicz, D; Drozdowski, M; Kisielewski, J; Lukasiewicz, T; Sahraoui, B

    2006-05-11

    It has been revealed that lanthanum calcium borate (La2CaB10O19) crystals show two-photon absorption (TPA) induced by a UV laser field. UV-induced TPA measurements were performed in the spectral range of 475-1130 nm using as fundamental beam the third harmonics of the 28 ps Nd-YAG pulsed laser as a pumping beam for LiB3O5 optical parametrized generator using Z-scan method. Investigations performed by the Z-scan method were done during illumination by a Xe-F laser (lambda = 217 nm) as a photoinducing (pumping) beam. The pumping laser beam created a thin surface layer (about 80-90 nm) that was the source of the observed photoinduced TPA. The highest values of the TPA beta coefficients were achieved for polarization of the pumping light directed along the second-order crystallographic axis of the investigated crystals. The obtained values of the TPA coefficients were higher than those for the BiB3O6 crystals investigated earlier by us. PMID:16671719

  10. Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation

    SciTech Connect

    Wu, Y.; Ajo-Franklin, J.B.; Spycher, N.; Hubbard, S.S.; Zhang, G.; Williams, K.H.; Taylor, J.; Fujita, Y.; Smith, R.

    2011-07-15

    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 NH{sub 4}{sup +} 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.

  11. Geophysical Monitoring and Reactive Transport Modeling of Ureolytically-Driven Calcium Carbonate Precipitation

    SciTech Connect

    Yuxin Wu; Jonathan B. Ajo-Franklin; Nicolas Spycher; Susan S. Hubbard; Guoxiang Zhang; Kenneth H. Williams; Joanna Taylor; Yoshiko Fujita; Robert Smith

    2011-09-01

    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.

  12. 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

  13. Crystal structure analysis reveals Pseudomonas PilY1 as an essential calcium-dependent regulator of bacterial surface motility

    SciTech Connect

    Orans, Jillian; Johnson, Michael D.L.; Coggan, Kimberly A.; Sperlazza, Justin R.; Heiniger, Ryan W.; Wolfgang, Matthew C.; Redinbo, Matthew R. (UNC)

    2010-09-21

    Several bacterial pathogens require the 'twitching' motility produced by filamentous type IV pili (T4P) to establish and maintain human infections. Two cytoplasmic ATPases function as an oscillatory motor that powers twitching motility via cycles of pilus extension and retraction. The regulation of this motor, however, has remained a mystery. We present the 2.1 {angstrom} resolution crystal structure of the Pseudomonas aeruginosa pilus-biogenesis factor PilY1, and identify a single site on this protein required for bacterial translocation. The structure reveals a modified {beta}-propeller fold and a distinct EF-hand-like calcium-binding site conserved in pathogens with retractile T4P. We show that preventing calcium binding by PilY1 using either an exogenous calcium chelator or mutation of a single residue disrupts Pseudomonas twitching motility by eliminating surface pili. In contrast, placing a lysine in this site to mimic the charge of a bound calcium interferes with motility in the opposite manner - by producing an abundance of nonfunctional surface pili. Our data indicate that calcium binding and release by the unique loop identified in the PilY1 crystal structure controls the opposing forces of pilus extension and retraction. Thus, PilY1 is an essential, calcium-dependent regulator of bacterial twitching motility.

  14. 35-GHz Measurements of Carbon Dioxide Crystals

    NASA Technical Reports Server (NTRS)

    Foster, J.; Chang, A.; Hall, D.; Tait, A.; Klein, A.

    1998-01-01

    In order to maximize our knowledge of the martian polar caps, it is important to compare and contrast the behavior of both frozen H2O and CO2 in different parts of the electromagnetic spectrum. Relatively little attention has been given, thus far, to observing the thermal microwave part of the spectrum. In this experiment, passive microwave radiation emanating from within a 33-cm snowpack was measured with a 35-GHz hand-held radiometer, and in addition to the natural snow measurements, the radiometer was used to measure the microwave emission and scattering from layers of manufactured CO2 (dry ice) crystals. A 1 square meter plate of aluminum sheet metal was positioned beneath the natural snow so that microwave emissions from the underlying soil layers would be minimized. 35 GHz measurements of this plate were made through the 33-cm snowpack. Layers of the snow were removed and measurements were repeated for the diminishing snowpack until the bare plate was in view. Then, 9 cm of CO2 crystals were deposited onto the sheet-metal plate, and as was the case for the natural snow, hand-held measurements were made each time the thickness of the deposit was altered. These CO2 crystals were -0.65 cm in diameter and were cylindrical. The temperature of the dry ice was -76 C, whereas the temperature at the top of the snowpack was -1.9 C (the air temperature was -3 C). Two additional 9-cm increments were placed on top of the existing CO2 crystals, resulting in a total thickness of 27 cm of dry ice. After this series of measurements was made, the CO2 crystals were then placed on top of the snowpack, and as before, measurements were made using the 35-GHz radiometer. As a final part of this experiment, soil particles were spread on top of the dry ice, and once again, microwave measurements were made with the 35-GHz radiometer.

  15. Medicago truncatula-derived calcium oxalate crystals have a negative impact on chewing insect performance via their physical properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant structural traits often act as defenses against herbivorous insects, causing them to avoid feeding on a given plant or tissue. Mineral crystals of calcium oxalate in Medicago truncatula Gaertn. (Fabaceae) leaves have previously been shown to be effective deterrents of lepidopteran insect feedi...

  16. CALCIUM OXALATE CRYSTAL MACROPATTERN IN LEAVES OF SPECIES FROM GROUPS GLYCINE AND SHUTERIA (GLYCININAE; PHASEOLEAE; PAPILIONOIDEAE; FABACEAE)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium oxalate crystals associated with leaf veins and mesophyll was determined for taxa in two groups Glycine and Shuteria of subtribe Glycininae. Trichomes and veins were identified as additional characters. The annual and wild perennial Glycine species have the most reduced characters by gener...

  17. Physical characteristics of calcium oxalate crystals as determinants in structural defense against chewing insects in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to the numerous chemical defenses that plants employ to fend off insect herbivores, simple structural components can also play important roles in effective protection. Our investigations have shown that plant crystals of calcium oxalate can function in insect defense. The isolation of ca...

  18. Crystal structure of S-glutathiolated carbonic anhydrase III

    Microsoft Academic Search

    Robert J. Mallis; Bradley W. Poland; Tapan K. Chatterjee; Rory A. Fisher; Steven Darmawan; Richard B. Honzatko; James A. Thomas

    2000-01-01

    S-Glutathiolation of carbonic anhydrase III (CAIII) occurs rapidly in hepatocytes under oxidative stress. The crystal structure of the S-glutathiolated CAIII from rat liver reveals covalent adducts on cysteines 183 and 188. Electrostatic charge and steric contacts at each modification site inversely correlate with the relative rates of reactivity of these cysteines toward glutathione (GSH). Diffuse electron density associated with the

  19. Chemistry of calcium carbonate-rich shallow water sediments in the Bahamas

    SciTech Connect

    Morse, J.W.; Zullig, J.J.; Bernstein, L.D.; Millero, F.J.; Milne, P.; Mucci, A.; Choppin, G.R.

    1985-02-01

    The geochemistry of calcium carbonate-rich sediments from a variety of environments throughout the Bahamas was investigated with particular emphasis on the factors that control the pore water chemistry. Most sediments are supersaturated with respect to aragonite, the most abundant carbonate component. Experimental studies indicate that the observed in situ calcium carbonate ion activity products can often be produced as reversible metastable equilibria between the sediments and seawater. This is interpreted as being the result of interactions between the solutions and the minor high Mg-calcite component present in these sediments. Although the overlying waters are more supersaturated than the pore waters, carbonate dissolution, not precipitation, dominates in these sediments as a result of organic matter oxidation and the resulting increase in P/sub CO/sub 2//. The carbonate sediments of the Bahamas are remarkable for their purity, with the exception of special environments such as mangrove swamps and tidal flats with algal mats. Organic matter and heavy metal content is extremely low. Only minor sulfate reduction is occurring in most sediments. Phosphate is undetectable in all pore waters, probably as a result of adsorption on carbonate mineral surfaces. Other dissolved pore water components such as ammonia and DOC are much lower than typically found in shallow water fine-grained terrigeneous sediments.

  20. X-ray absorption spectroscopy identifies calcium-uranyl-carbonate complexes at environmental concentrations.

    SciTech Connect

    Kelly, S. D.; Kemner, K. M.; Brooks, S. C.; Biosciences Division; ORNL

    2007-01-01

    Current research on bioremediation of uranium-contaminated groundwater focuses on supplying indigenous metal-reducing bacteria with the appropriate metabolic requirements to induce microbiological reduction of soluble uranium(VI) to poorly soluble uranium(IV). Recent studies of uranium(VI) bioreduction in the presence of environmentally relevant levels of calcium revealed limited and slowed uranium(VI) reduction and the formation of a Ca-UO{sub 2}-CO{sub 3} complex. However, the stoichiometry of the complex is poorly defined and may be complicated by the presence of a Na-UO{sub 2}-CO{sub 3} complex. Such a complex might exist even at high calcium concentrations, as some UO{sub 2}-CO{sub 3} complexes will still be present. The number of calcium and/or sodium atoms coordinated to a uranyl carbonate complex will determine the net charge of the complex. Such a change in aqueous speciation of uranium(VI) in calcareous groundwater may affect the fate and transport properties of uranium. In this paper, we present the results from X-ray absorption fine structure (XAFS) measurements of a series of solutions containing 50 {micro}M uranium(VI) and 30 mM sodium bicarbonate, with various calcium concentrations of 0-5 mM. Use of the data series reduces the uncertainty in the number of calcium atoms bound to the UO{sub 2}-CO{sub 3} complex to approximately 0.6 and enables spectroscopic identification of the Na-UO{sub 2}-CO{sub 3} complex. At nearly neutral pH values, the numbers of sodium and calcium atoms bound to the uranyl triscarbonate species are found to depend on the calcium concentration, as predicted by speciation calculations.