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Sample records for calcium orthophosphates crystallization

  1. Calcium orthophosphates in dentistry.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2013-06-01

    Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.

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

    Science.gov (United States)

    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.

  3. Calcium Orthophosphate-Based Bioceramics

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    Sergey V. Dorozhkin

    2013-09-01

    Full Text Available Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

  4. Investigation of the crystal structure, dielectrical, electrical and microstructural properties of cobalt-containing calcium orthophosphates

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    Omer Kaygili

    2015-06-01

    Full Text Available Pure hydroxyapatite and cobalt-containing calcium orthophosphate ceramics were synthesized by the sol–gel method and their properties were analyzed by Fourier transform infrared spectroscopy, X–ray diffraction, dielectrical impedance spectroscopy and scanning electron microscopy techniques. The average crystallite size of the samples was found to be 30–56 nm. The crystallinity was decreased gradually with the addition of Co. The resistance values were found to be ~1012 Ω. Dielectric permittivity and alternating current conductivity of all the samples showed substantial changes in the presence of cobalt. The morphology and particle size distribution of all the samples were changed with increasing amount of Co. In addition, the high content of Co ions was found to both destroy the apatitic structure of the hydroxyapatite and cause the calcium deficiency. The results indicated that, in presence of high amounts of Co, Ca9.5Co(PO47 ceramics could be prepared. Normal 0 21 false false false MicrosoftInternetExplorer4 DOI: http://dx.doi.org/10.5755/j01.ms.21.2.6251

  5. Self-Setting Calcium Orthophosphate Formulations

    Science.gov (United States)

    Dorozhkin, Sergey V.

    2013-01-01

    In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided. PMID:24956191

  6. Crystal structure of tris(hydroxylammonium orthophosphate

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    Malte Leinemann

    2015-11-01

    Full Text Available The crystal structure of the title salt, ([H3NOH]+3·[PO4]3−, consists of discrete hydroxylammonium cations and orthophosphate anions. The atoms of the cation occupy general positions, whereas the anion is located on a threefold rotation axis that runs through the phosphorus atom and one of the phosphate O atoms. In the crystal structure, cations and anions are linked by intermolecular O—H...O and N—H...O hydrogen bonds into a three-dimensional network. Altogether, one very strong O—H...O, two N—H...O hydrogen bonds of medium strength and two weaker bifurcated N—H...O interactions are observed.

  7. Calcium Orthophosphates as Bioceramics: State of the Art

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    Sergey V. Dorozhkin

    2010-11-01

    Full Text Available In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30–40 years. Namely, by structural and compositional control, it became possible to choose whether calcium orthophosphate bioceramics were biologically stable once incorporated within the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics—which is able to promote regeneration of bones—was developed. Presently, calcium orthophosphate bioceramics are available in the form of particulates, blocks, cements, coatings, customized designs for specific applications and as injectable composites in a polymer carrier. Current biomedical applications include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Exploratory studies demonstrate potential applications of calcium orthophosphate bioceramics as scaffolds, drug delivery systems, as well as carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  8. Nanodimensional and Nanocrystalline Apatites and Other Calcium Orthophosphates in Biomedical Engineering, Biology and Medicine

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    Sergey V. Dorozhkin

    2009-11-01

    Full Text Available Recent developments in biomineralization have already demonstrated that nanosized particles play an important role in the formation of hard tissues of animals. Namely, the basic inorganic building blocks of bones and teeth of mammals are nanodimensional and nanocrystalline calcium orthophosphates (in the form of apatites of a biological origin. In mammals, tens to hundreds nanocrystals of a biological apatite were found to be combined into self-assembled structures under the control of various bioorganic matrixes. In addition, the structures of both dental enamel and bones could be mimicked by an oriented aggregation of nanosized calcium orthophosphates, determined by the biomolecules. The application and prospective use of nanodimensional and nanocrystalline calcium orthophosphates for a clinical repair of damaged bones and teeth are also known. For example, a greater viability and a better proliferation of various types of cells were detected on smaller crystals of calcium orthophosphates. Thus, the nanodimensional and nanocrystalline forms of calcium orthophosphates have a great potential to revolutionize the field of hard tissue engineering starting from bone repair and augmentation to the controlled drug delivery devices. This paper reviews current state of knowledge and recent developments of this subject starting from the synthesis and characterization to biomedical and clinical applications. More to the point, this review provides possible directions of future research and development.

  9. Calcium orthophosphate coatings on magnesium and its biodegradable alloys.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2014-07-01

    Biodegradable metals have been suggested as revolutionary biomaterials for bone-grafting therapies. Of these metals, magnesium (Mg) and its biodegradable alloys appear to be particularly attractive candidates due to their non-toxicity and as their mechanical properties match those of bones better than other metals do. Being light, biocompatible and biodegradable, Mg-based metallic implants have several advantages over other implantable metals currently in use, such as eliminating both the effects of stress shielding and the requirement of a second surgery for implant removal. Unfortunately, the fast degradation rates of Mg and its biodegradable alloys in the aggressive physiological environment impose limitations on their clinical applications. This necessitates development of implants with controlled degradation rates to match the kinetics of bone healing. Application of protective but biocompatible and biodegradable coatings able to delay the onset of Mg corrosion appears to be a reasonable solution. Since calcium orthophosphates are well tolerated by living organisms, they appear to be the excellent candidates for such coatings. Nevertheless, both the high chemical reactivity and the low melting point of Mg require specific parameters for successful deposition of calcium orthophosphate coatings. This review provides an overview of current coating techniques used for deposition of calcium orthophosphates on Mg and its biodegradable alloys. The literature analysis revealed that in all cases the calcium orthophosphate protective coatings both increased the corrosion resistance of Mg-based metallic biomaterials and improved their surface biocompatibility. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Crystal structure of strontium dinickel iron orthophosphate

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    Said Ouaatta

    2015-10-01

    Full Text Available The title compound, SrNi2Fe(PO43, synthesized by solid-state reaction, crystallizes in an ordered variant of the α-CrPO4 structure. In the asymmetric unit, two O atoms are in general positions, whereas all others atoms are in special positions of the space group Imma: the Sr cation and one P atom occupy the Wyckoff position 4e (mm2, Fe is on 4b (2/m, Ni and the other P atom are on 8g (2, one O atom is on 8h (m and the other on 8i (m. The three-dimensional framework of the crystal structure is built up by [PO4] tetrahedra, [FeO6] octahedra and [Ni2O10] dimers of edge-sharing octahedra, linked through common corners or edges. This structure comprises two types of layers stacked alternately along the [100] direction. The first layer is formed by edge-sharing octahedra ([Ni2O10] dimer linked to [PO4] tetrahedra via common edges while the second layer is built up from a strontium row followed by infinite chains of alternating [PO4] tetrahedra and FeO6 octahedra sharing apices. The layers are held together through vertices of [PO4] tetrahedra and [FeO6] octahedra, leading to the appearance of two types of tunnels parallel to the a- and b-axis directions in which the Sr cations are located. Each Sr cation is surrounded by eight O atoms.

  11. Synthesis and crystal structure of calcium dizinc iron(III tris(orthophosphate, CaZn2Fe(PO43

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    Jamal Khmiyas

    2016-09-01

    Full Text Available Single crystals of the title compound, CaZn2Fe(PO43, were synthesized by conventional solid-state reaction. In the asymmetric unit, all atoms are located in fully occupied general positions of the P21/c space group. The zinc atoms are located on two crystallographically independent sites with tetrahedral and distorted triangular-based bipyramidal geometries. Two edge-sharing triangular bipyramidal ZnO5 units form a dimer, which is linked to slightly deformed FeO6 octahedra via a common edge. The resulting chains are interconnected through PO4 tetrahedra to form a layer perpendicular to the b axis. Moreover, the remaining PO4 and ZnO4 tetrahedra are linked together through common vertices to form tapes parallel to the c axis and surrounding a chain of Ca2+ cations to build a sheet, also perpendicular to the b axis. The stacking of the two layers along the b axis leads to the resulting three-dimensional framework, which defines channels in which the Ca2+ cations are located, each cation being coordinated by seven oxygen atoms.

  12. CALCIUM ORTHOPHOSPHATES HYDRATES: FORMATION, STABILITY AND INFLUENCE ON STANDARD PROPERTIES OF PORTLAND CEMENT

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    Kaziliunas A.

    2013-12-01

    Full Text Available Preparation of phosphogypsum to produce the binders requires a much higher input than preparation of natural gypsum stone. This makes it uncompetitive material. The investigations presented therein are meant to reduce this input by looking for the ways of rendering impurities harmless. Soluble acid orthophosphates are the main harmful impurity of phosphogypsum. The studies show that dry insoluble calcium orthophosphates hydrates (1.09 % and 2.18 % P2O5 in gypsum have little effect on W/C, setting times and soundness of Portland cement pastes. Insoluble calcium orthophosphates hydrates {CaHPO4∙2H2O, Ca8(HPO42(PO44∙5H2O and Ca9(HPO4(PO45(OH∙4H2O} formed in acidic medium (pH = 4.2 - 5.9 have been destroyed in alkaline medium and reduce standard compressive strength of cement up to 28 %. Calcium orthophosphates hydrates of hydroxyapatite group are stable in alcaline medium, while in dry state they reduce the standard compressive strength of cement until 10 %, but their suspensions prolong setting times of Portland cement as soluble orthophosphates – 2 - 3 times. Alkalis in cement increase pH of paste, but do not change the process of formation of calcium orthophosphates hydrates of hydroxyapatite group: it takes place through an intermediate phase - CaHPO4·2H2O, whose transformation into apatite lasts for 2 - 3 months.

  13. Formation and characterization of calcium orthophosphates in the presence of two different acidic macromolecules

    Science.gov (United States)

    Pelin, Irina M.; Maier, Vasilica; Suflet, Dana M.; Popescu, Irina; Darie-Nita, Raluca N.; Aflori, Magdalena; Butnaru, Maria

    2017-10-01

    The synthetic nanocrystalline calcium orthophosphates have a notable bioactivity due to the chemical similarity with biological apatite from calcified tissues. In mineralized tissues, the highly ordered structures come from organized assemblies of biomacromolecules and inorganic nanoparticles. One of the purposes of this work was to study the effect of two types of acidic macromolecules: atelocollagen and phosphorylated curdlan onto calcium orthophosphates formation after 30 days of maturation at 2 ± 2 °C. The resulted samples after a long aging time, either calcium orthophosphates or composites, were first investigated by FT-IR spectroscopy and X-ray diffractometry and the results indicated that precipitated hydroxyapatite with low crystallinity was obtained when the synthesis was performed in the presence of phosphorylated curdlan. The macromolecules influenced the morphology of the particles as shown by scanning and transmission electron microscopy. The presence of macromolecules as demonstrated by thermal investigation also influenced the rheological properties of the samples. The second purpose of the work was to evaluate the cytotoxicity of the samples using the MTT assay, and the results revealed very good cells viability. The preliminary results are encouraging regarding the use of these materials for further tests in order to develop injectable bone substitutes.

  14. Calcium orthophosphate-based bone cements (CPCs): Applications, antibiotic release and alternatives to antibiotics.

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    Van Staden, Anton D; Dicks, Leon M T

    2012-06-26

    Calcium orthophosphate bone cements (CPCs) are widely used in orthopedic surgery. Implants are highly susceptible to infection and often lead to the formation of microbial biofilms. Antibiotics are often incorporated into bone cement to prevent infection. The increase in the number of microorganisms acquiring or developing resistance to antibiotics, such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), is a major concern. Bacteriocins (antimicrobial peptides) offer an alternative to antibiotics. Their mode of activity involves permanent destabilization of the plasma membrane of target cells. A number of broad-spectrum bacteriocins produced by lactic acid bacteria and Bacillus spp. have recently been reported. In this REVIEW the major characteristics of calcium phosphate bone cements, prosthetic joint-associated infections, and treatment of these infections is discussed. The role of antimicrobial agents in CPCs is discussed and the possibility of incorporating bacteriocins in prosthetic devices is investigated.

  15. Crystal structures, anisotropic growth, and optical properties: controlled synthesis of lanthanide orthophosphate one-dimensional nanomaterials.

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    Yan, Ruoxue; Sun, Xiaoming; Wang, Xun; Peng, Qing; Li, Yadong

    2005-03-18

    The fundamental understanding of the relationship between crystal structure and the dynamic processes of anisotropic growth on the nanoscale, and exploration of the key factors governing the evolution of physical properties in functional nanomaterials, have become two of the most urgent and challenging issues in the fabrication and exploitation of functional nanomaterials with designed properties and the development of nanoscale devices. Herein, we show how structural and kinetic factors govern the tendency for anisotropic growth of such materials under hydrothermal conditions, and how the crystal structure and morphology influence the optical properties of Ln3+-doped nanocrystals. The synthesis of phase-pure and single-crystalline monoclinic, hexagonal, and tetragonal one-dimensional LnPO4 nanostructures of different aspect ratios by means of kinetically controlled hydrothermal growth processes is demonstrated. It is shown that the tendency for anisotropic growth under hydrothermal conditions can be enhanced simply by modifying the chemical potentials of species in the reaction solution through the use of carefully selected chelating ligands. A systematic study of the photoluminescence of various Eu3+-doped lanthanide phosphates has revealed that the optical properties of these nanophosphors are strongly dependent on their crystal structures and morphologies.

  16. OSTEOPOROSIS IN CALCIUM PYROPHOSPHATE CRYSTAL DEPOSITION DISEASE

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    S A Vladimirov

    2013-01-01

    Full Text Available Objective: to study the incidence of osteoporosis (OP in patients with calcium pyrophosphate crystal deposition disease (CPCDD. Subjects and methods. Eighty patients with CPCDD were examined. Bone mineral density (BMD of the forearm, lumbar spine, and femoral neck was determined by dual-energy X-ray absorptiometry. Laboratory diagnosis involved determination of the blood levels of C-reactive protein, parathyroid hormone, calcium, magnesium, and phosphorus and the daily urinary excretion of calcium and phosphates. Results. The patients with OP were significantly older than those with normal BMD and osteopenia. Forearm bones were the most common isolated location of OP and osteopenia. Injuries in the history, traumatic fractures, and the intake of diuretics were somewhat more common in the patients diagnosed with OP. The incidence of hyperparathyroidism did not differ significantly in the groups.

  17. Probable functions of calcium oxalate crystals in different tissues of ...

    African Journals Online (AJOL)

    Representatives of seven major edible aroid accessions were screened for calcium oxalate using standard histochemical methods. All the accessions were noted to contain calcium oxalate in the forms of raphide bundles and intra-amylar crystals. The crystals were widely present in all parts of the plants including spongy ...

  18. Crystal growth and morphology of calcium oxalates and carbonates

    NARCIS (Netherlands)

    Heijnen, W.M.M.

    1986-01-01

    The main purpose of the research described in this thesis is to establish a relationship between the crystal structure and morphology of calcium oxalate and calcium carbonate crystals grown from aqueous solutions. Starting point is the PBC (Periodic Bond Chain) theory formulated by Hartman and

  19. INFLUENCE OF POLYMERIC ADDITIVES ON CRYSTALLIZATION OF CALCIUM SULPHATE DIHYDRATE

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    Ustinova Yulia Valer’evna

    2013-04-01

    Full Text Available Currently, functional additives are widely spread in the production of inorganic dry mixtures. However, their impact on the microstructure of products, generated in the process of hardening of inorganic binders, is understudied. In this context, the goal of the work is the study of calcium sulfate dihydrate (CaSO •2H O crystallization. Super plasticizer based on sulfonated melamine-formaldehyde resin, methylcellulose and vinyl acetate, ethylene and vinyl chloride copolymer powder were selected for studies. First, pure calcium sulfate dihydrate crystals were synthesized. Then, synthesized calcium sulfate dihydrate crystals were exposed to the X-ray analysis to determine the nature of influence of polymer additives on the shape and dimensions of crystals. Possible combinations of simple forms of CaSO •2H O were identified by the X-ray analysis and the special software. Electronic microscopy analysis was performed to validate models of calcium sulfate dihydrate crystals. All plasticizers influence the crystallization of calcium sulfate dihydrate. The influence of additives on the shape and dimensions of crystals of calcium sulfate dihydrate can be explained by the fact that molecules of sulfonated melamine-formaldehyde resins, methylcellulose, and copolymers of vinyl acetate, ethylene and vinyl chloride are absorbed by crystal faces. It is proven that the method of X-ray analysis can be used to predict the shape and habitus of crystals.

  20. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    Unknown

    tartaric acid content of the gel is completely exhausted partly through the formation of calcium tartrate crystals and partly through the demonstrable loss of tartaric acid to the solution at the top in the gel region close to the super- natant liquid. Normally, many small crystals grow in the gel medium and only a few of them are ...

  1. Electron imaging of calcium oxalate crystals in beagle dogs’ urine

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    Walaa I. Mohamaden

    2014-06-01

    Full Text Available Calcium oxalate crystalluria appears to be a common problem in most of small animal clinics. This current study aimed at inducing a condition of oxalate crystalluria in beagles and record the primary changes in canine blood and urine on response to oxalates injection. 15 dogs were divided into two groups; those in the treatment group were injected intravenously with 0.5 M potassium oxalate and the dogs of control group were injected with physiological saline for five successive days. Urine test revealed a significant decrease in urinary creatinine and urinary urea nitrogen levels. The ultrastructural examination of urine sediment showed typical and atypical phases of calcium oxalate crystals and the X-ray defractionation of these crystals showed high content of calcium in addition to other minerals. Therefore potassium oxalate injection may provide an example of calcium oxalate crystalluria which may answer some question around the pathogenesis of this problem in dogs.

  2. Effect of Ultrasound on Calcium Carbonate Crystallization

    NARCIS (Netherlands)

    Wagterveld, R.M.

    2013-01-01

    Scaling comprises the formation of hard mineral deposits on process or membrane equipment and calcium carbonate is the most common scaling salt. Especially in reverse osmosis (RO) membrane systems, scale formation has always been a serious limitation, causing flux decline, membrane degradation, loss

  3. On the growth of calcium tartrate tetrahydrate single crystals

    Indian Academy of Sciences (India)

    . Calcium formate mixed with formic acid was taken as the supernatant solution. It was observed that the nucleation density was reduced and the size of the crystals was improved to a large extent compared to the conventional way of growing ...

  4. Calcium oxalate crystal growth modification; investigations with confocal Raman microscopy

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    McMulkin, Calum J.; Massi, Massimiliano; Jones, Franca

    2017-06-01

    Confocal Raman Microscopy (CRM) in combination with a photophysical investigation has been employed to give insight into the interaction between calcium oxalate monohydrate (COM) and a series of tetrazole containing crystal growth modifier's (CGM's), in conjunction with characterisation of morphological changes using scanning electron and optical microscopy. The tetrazole CGM's were found to interact by surface adsorption with minimal morphological changes to the COM crystals however, significant interactions via chemisorption were observed; it was discovered that the chemisorption is sufficiently strong for aggregation of the tetrazole species to occur within the crystal during crystallisation.

  5. Polymorph-selective crystallization of calcium carbonate inspired by biomineralization

    Science.gov (United States)

    Kim, Il Won

    This dissertation primarily examines bioinspired mineralization, focusing on the polymorph-selective crystallization of calcium carbonate. (1) The effect of epitaxy on the polymorphic control of calcium carbonate was studied with aragonite-type inorganic substrates. The critical epitaxial mismatch for aragonite growth, when conditions disfavor aragonite, seems to be less than 7.1%. Larger epitaxial strain appeared to prohibit aragonite formation even though the substrates had the same crystal structure. The epitaxy required for aragonite nucleation seems to be more precise than that often suggested for biological systems. (2) Polymers of different aqueous-solution properties were tested to observe the effect on the crystallization of calcium carbonate. Near exclusive formation of aragonite was attained through the inhibition of more stable calcite with poly(vinyl alcohol). The contributing characteristics of poly(vinyl alcohol) seemed to be its ability to hydrogen bond and its tendency to adsorb non-specifically onto solid surfaces. Similar inhibition activity is suggested for various biomacromolecules involved in biogenic aragonite formation of mollusks, with the biomacromolecules acting in the same way as poly(vinyl alcohol). (3) Polymer surfaces imprinted by aragonite-type crystals (strontium carbonate) were studied as substrates for the crystallization of calcium carbonate. Only calcite formed under vaterite-, aragonite-, and calcite-favorable conditions. This result seemed to arise from the nature of functional groups, rather than from the molecular structure of the imprint. Interaction between the functional groups and calcium carbonate is suggested to have enhanced the crystallization rate, resulting in the rapid formation of the thermodynamically stable calcite irrespective of the bulk crystallization conditions. (4) A catechol-based monomer was synthesized in the course of developing a dental adhesive, which mimics the functionalities of mussel adhesive

  6. Effect of Calcium Additive on the Crystallization of Struvite

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    Perwitasari Dyah Suci

    2016-01-01

    Full Text Available Crystallization of struvite [MgNH4PO4.6H2O] may lead to the deposition of scale which may create significant problems in the process pipes, pumps and other industrial equipment. However, struvite precipitation can be benefited for phosphate recovery for use of fertilizer. The aim at the present work was to investigate calcium additive on struvite precipitation. The experiment was carried out in a batch mode using a 1-liter Pyrex glass vessel mechanically agitated for 200 rpm. The scale-forming solution was prepared for mixing solutions to MgCl2 and NH4H2PO4 with Mg+2 , NH4+ and PO4-3 in a molar ratio of 1: 1:1. The crystallization temperature of 30 and 40 °C was selected. Ca was added into the crystallizing solution to chloride dihydrate 0.4M (CaCl2•2H2O. Then each solution was pH adjusted to 9 by addition of KOH. The crystals obtained were characterized using SEM for morphology, EDS for elemental analysis as well as XRPD Rietveld analysis for crystaline phases. The induction periods varied from 10 to 90 min, which means that the struvite crystals began forming 10 to 90 min after mixing of the solution. It was observed that the Ca additive may inhibit the struvite crystallization. SEM analysis revealed that the struvite crystals obtained were predominantly of irregular prismatic morphology. Furthermore, the EDS pattern revealed that the elemental composition of the crystals consisted of Ca, Cl, S Mg, N, and P, providing that many crystalline phase found in the crystals such as Gypsum, CaCl2, struvite, struvite-(K and sylvite. It was observed that the Ca additive appeared to inhibit the struvite crystallization.

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

    Science.gov (United States)

    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.

  8. Efficacy of Mixtures of Magnesium, Citrate and Phytate as Calcium Oxalate Crystallization Inhibitors in Urine.

    Science.gov (United States)

    Grases, Felix; Rodriguez, Adrian; Costa-Bauza, Antonia

    2015-09-01

    The main aim of the current study was to evaluate the effectiveness of mixtures of magnesium, citrate and phytate as calcium oxalate crystallization inhibitors. A turbidimetric assay in synthetic urine was performed to obtain induction times for calcium oxalate crystallization in the absence and presence of different mixtures of inhibitors. The morphology of calcium oxalate crystals in the absence or presence of inhibitors and mixtures of the inhibitors was evaluated in 2 crystallization experiments at low and high calcium oxalate supersaturation. The crystals formed were examined using scanning electron microscopy. Examination of crystallization induction times revealed clear inhibitory effects of magnesium, citrate and phytate on calcium oxalate crystallization, supporting usefulness in the treatment and prevention of calcium oxalate nephrolithiasis. Significant synergistic effects between magnesium and phytate were observed. Scanning electron microscopy images revealed that phytate is a powerful crystal growth inhibitor of calcium oxalate, totally preventing the formation of trihydrate and monohydrate. In addition to crystallization inhibition capacity, citrate and magnesium avoided calcium oxalate crystallization by decreasing its supersaturation. The synergistic effect between magnesium and phytate on calcium oxalate crystallization suggests that a combination of these 2 compounds may be highly useful as antilithiasis therapy. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  9. Pathogenic Role of Basic Calcium Phosphate Crystals in Destructive Arthropathies

    Science.gov (United States)

    Ea, Hang-Korng; Chobaz, Véronique; Nguyen, Christelle; Nasi, Sonia; van Lent, Peter; Daudon, Michel; Dessombz, Arnaud; Bazin, Dominique; McCarthy, Geraldine; Jolles-Haeberli, Brigitte; Ives, Annette; Van Linthoudt, Daniel; So, Alexander; Lioté, Frédéric; Busso, Nathalie

    2013-01-01

    Background basic calcium phosphate (BCP) crystals are commonly found in osteoarthritis (OA) and are associated with cartilage destruction. BCP crystals induce in vitro catabolic responses with the production of metalloproteases and inflammatory cytokines such as interleukin-1 (IL-1). In vivo, IL-1 production induced by BCP crystals is both dependant and independent of NLRP3 inflammasome. We aimed to clarify 1/ the role of BCP crystals in cartilage destruction and 2/ the role of IL-1 and NLRP3 inflammasome in cartilage degradation related to BCP crystals. Methodology/ Principal Findings synovial membranes isolated from OA knees were analysed by alizarin Red and FTIR. Pyrogen free BCP crystals were injected into right knees of WT, NLRP3 -/-, ASC -/-, IL-1α -/- and IL-1β-/- mice and PBS was injected into left knees. To assess the role of IL-1, WT mice were treated by intra-peritoneal injections of anakinra, the IL-1Ra recombinant protein, or PBS. Articular destruction was studied at d4, d17 and d30 assessing synovial inflammation, proteoglycan loss and chondrocyte apoptosis. BCP crystals were frequently found in OA synovial membranes including low grade OA. BCP crystals injected into murine knee joints provoked synovial inflammation characterized by synovial macrophage infiltration that persisted at day 30, cartilage degradation as evidenced by loss of proteoglycan staining by Safranin-O and concomitant expression of VDIPEN epitopes, and increased chondrocyte apoptosis. BCP crystal-induced synovitis was totally independent of IL-1α and IL-1β signalling and no alterations of inflammation were observed in mice deficient for components of the NLRP3-inflammasome, IL-1α or IL-1β. Similarly, treatment with anakinra did not prevent BCP crystal effects. In vitro, BCP crystals elicited enhanced transcription of matrix degrading and pro-inflammatory genes in macrophages. Conclusions/ Significance intra-articular BCP crystals can elicit synovial inflammation and cartilage

  10. Egg-white-mediated crystallization of calcium carbonate

    Science.gov (United States)

    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.

  11. Crystal phase of fibrous calcium phosphates prepared with sodium alginate.

    Science.gov (United States)

    Hayashizaki, J; Ban, S; Arimoto, N; Kato, N; Kimura, Y; Hasegawa, J

    1995-12-01

    This study investigated the effects of preparation conditions on the crystal phase of the fired fiber prepared with sodium alginate. Hydroxyapatite, Ca10(PO4)6(OH)2, hereafter referred to as HA, was only formed in fiber fired at 900 degrees C under proper conditions. There was no significant difference in the crystal phase of the fired fibers prepared using different sodium alginate concentrations and syringe nozzle diameter, although fiber diameters were enlarged with increasing in either. No effects of phosphate type on the crystal phase of the fired fiber were found, but the aging time and the rinsing time had great effects. Sodium calcium phosphate, NaCaPO4, and HA were formed when the aging time was shorter than 5 min. Chlorapatite, Ca5Cl(PO4)3, and HA were formed when the rinsing time was shorter than 3 sec, and HA was formed when the rinsing time was 5 min to 1 hour, beta-TCP, beta-Ca3 (PO4)2, and HA were formed when the rinsing time exceeded 2 weeks.

  12. In vitro effect of wheat bran (Triticum aestivum) extract on calcium oxalate urolithiasis crystallization.

    Science.gov (United States)

    Sekkoum, Khaled; Cheriti, Abdelkrim; Taleb, Safia

    2011-10-01

    Urolithiasis can lead to the loss of renal function in some cases. In this study, we tested the inhibiting effect of wheat bran (Triticum aestivum L) extract on calcium oxalate crystallization in a turbidimetric model, by FTIR spectroscopy, and polarized microscopy. The results show that this plant extract has a major inhibitory effect on calcium oxalate crystallization.

  13. Posidonia oceanica (L.) fibers as a potential low-cost adsorbent for the removal and recovery of orthophosphate.

    Science.gov (United States)

    Wahab, Mohamed Ali; Hassine, Rafik Ben; Jellali, Salah

    2011-07-15

    Adsorption efficiency of orthophosphate from aqueous solution onto Posidonia oceanica fibers (POF) as a raw, natural and abundant material was investigated and compared with other common natural materials. A series of batch tests were undertaken to assess the effect of the system variables, i.e. initial aqueous orthophosphate concentration, contact time, adsorbent dosage, pH and temperature. Results indicate that orthophosphate uptake increased with increasing initial orthophosphate concentration, temperature and adsorbent dosage and decreased with increasing pH values. The maximum adsorption capacity (Q(m)) determined from the Langmuir isotherm was calculated to be 7.45 mg g(-1) for the studied orthophosphates concentration range of 15-100 mg L(-1), pH 7; adsorbent dosage of 2 g L(-1) and temperature of 20±2°C. The adsorption data were very well described by the pseudo-second order model predicting a chemisorption process. The energy dispersive spectroscopy (EDS) and FTIR analysis before and after adsorption of orthophosphate onto POF showed that the main involved mechanisms are ligand exchange between orthophosphate and Cl(-), SO(4)(2-) and OH(-) and precipitation with calcium. In comparison with other natural adsorbents, raw POF could be considered as one of the most efficient natural materials for the removal of orthophosphate with the possibility of agronomic reuse. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Posidonia oceanica (L.) fibers as a potential low-cost adsorbent for the removal and recovery of orthophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Wahab, Mohamed Ali, E-mail: waheb_med@yahoo.fr [University of Carthage, Water Research and Technologies Centre (CERTE), Wastewater Treatment and Recycling Laboratory (Tunisia); Ben Hassine, Rafik [International Environmental Green Technology (IGET) (Tunisia); Jellali, Salah, E-mail: salah.jallali@certe.rnrt.tn [University of Carthage, Water Research and Technologies Centre (CERTE), Wastewater Treatment and Recycling Laboratory (Tunisia)

    2011-07-15

    Adsorption efficiency of orthophosphate from aqueous solution onto Posidonia oceanica fibers (POF) as a raw, natural and abundant material was investigated and compared with other common natural materials. A series of batch tests were undertaken to assess the effect of the system variables, i.e. initial aqueous orthophosphate concentration, contact time, adsorbent dosage, pH and temperature. Results indicate that orthophosphate uptake increased with increasing initial orthophosphate concentration, temperature and adsorbent dosage and decreased with increasing pH values. The maximum adsorption capacity (Q{sub m}) determined from the Langmuir isotherm was calculated to be 7.45 mg g{sup -1} for the studied orthophosphates concentration range of 15-100 mg L{sup -1}, pH 7; adsorbent dosage of 2 g L{sup -1} and temperature of 20 {+-} 2{sup Degree-Sign }C . The adsorption data were very well described by the pseudo-second order model predicting a chemisorption process. The energy dispersive spectroscopy (EDS) and FTIR analysis before and after adsorption of orthophosphate onto POF showed that the main involved mechanisms are ligand exchange between orthophosphate and Cl{sup -}, SO{sub 4}{sup 2-} and OH{sup -} and precipitation with calcium. In comparison with other natural adsorbents, raw POF could be considered as one of the most efficient natural materials for the removal of orthophosphate with the possibility of agronomic reuse.

  15. The high prevalence of pathologic calcium crystals in pre-operative knees.

    Science.gov (United States)

    Derfus, Beth A; Kurian, Jason B; Butler, Jeffrey J; Daft, Laureen J; Carrera, Guillermo F; Ryan, Lawrence M; Rosenthal, Ann K

    2002-03-01

    Calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate (BCP) crystals are important in the pathogenesis of osteoarthritis (OA) but are under recognized even in end stage disease. We determined the prevalence of these calcium crystals in synovial fluid (SF) of persons undergoing total knee arthroplasty for degenerative arthritis. SF samples were obtained from 53 knee joints undergoing total arthroplasty for a pre-operative diagnosis of OA. SF were analyzed via compensated light microscopy for CPPD crystals and a semiquantitative radiometric assay for BCP crystals. Fifty pre-operative radiographs were analyzed and graded according to the scale of Kellgren and Lawrence. Patients had an average age of 70 years at the time of surgery. CPPD and/or BCP crystals were identified in 60% of SF. Overall radiographic scores correlated with mean concentrations of BCP crystals. Higher mean radiographic scores correlated with the presence of calcium-containing crystals of either type in SF Radiographic chondrocalcinosis was identified in only 31% of those with SF CPPD. Pathologic calcium crystals were present in a majority of SF at the time of total knee arthroplasty. Intraoperative SF analysis could conveniently identify pathologic calcium crystals providing information that may be relevant to the future care of the patient's replaced joint and that of other joints. This information could also potentially aid in predicting the likelihood of the need for contralateral total knee arthroplasty.

  16. [Effect of different culture conditions on carbonic anhydrase from Bacillus mucilaginosus inducing calcium carbonate crystal formation].

    Science.gov (United States)

    Zhou, Xueying; Du, Ye; Lian, Bin

    2010-07-01

    Effect of various culture conditions on the morphology, amount and carbonic anhydrase (CA) activity of Bacillus mucilaginosus were examined, as well as the effect on calcium carbonate crystal forming, shape and amount. The strain was inoculated in N-free or N-containing medium, and the bacterial morphology, number and CA activity were compared under different culture conditions. By collecting different cultures and adding them to the system of calcium carbonate crystallization we studied the relationship between the bacteria and the formation of calcium carbonate crystals. A small number of cell, capsular hypertrophy, lower CA activity in bacterial culture were obtained under N-free culture condition. In contrast, more biomass quantity, thin capsule, and high CA activity were got in the nitrogen-containing culture. In the calcium carbonate crystal system, adding N-free culture of bacteria produced a smooth surface of calcium carbonate crystals, larger volume but small density, the addition N-containing culture of bacteria formed rough surface, bigger density but smaller volume of calcium carbonate crystals. Different culture conditions can cause significant differences in bacterial amounts, capsular thickness and CA activity, and then influence the crystal growth and form of calcium carbonate.

  17. Effect of Blumea balsamifera extract on the phase and morphology of calcium oxalate crystals.

    Science.gov (United States)

    Montealegre, Charlimagne M; De Leon, Rizalinda L

    2017-10-01

    Calcium oxalate crystals are found in majority of kidney stones with calcium oxalate monohydrate (COM) as one of the primary types of kidney stones. Various methods of treatment exist, including herbal treatment in the Philippines that uses the medicinal herb Blumea balsamifera (B. balsamifera). The effect of B. balsamifera extract on the morphology of calcium oxalate crystals was studied by light microscopy, image analysis, powder X-ray diffraction and scanning electron microscopy. The extract decreased the crystal size by 5.22%-82.62% depending on the degree of supersaturation. Through analysis of the projected area of the crystals, the extract was found to shift the phase of the crystals from COM to calcium oxalate dihydrate (COD). This shift in phase is significant with a COM to COD shift of 88.26% at 0.5 mg/mL of extract and 91.53% at 1.0 mg/mL of extract. Scanning election microscopic (SEM) images revealed aggregation of crystals at 0 mg/mL of extract. At 1.0 mg/mL of extract, the scanning electron micrographs showed discernible crystal unit boundaries. B. balsamifera extract was observed to have decreased crystal size, shifted crystal phase from COM to COD and prevented the aggregation of calcium oxalate crystals.

  18. Bilateral Olecranon Bursitis – A Rare Clinical presentation of Calcium Pyrophosphate Crystal Deposition Disease

    Science.gov (United States)

    Patel, Jignesh; Girishkumar; Mruthyunjaya; Rupakumar, C. S

    2014-01-01

    Introduction: Calcium pyrophosphate crystal deposition disease (CPPD) is the most common form of crystal arthropathy second only to gout. Common clinical presentation is an acute monoarticular arthritis commonly occurring in knee joints. We presented a case of bilateral olecranon bursitis in a calcium pyrophosphate crystal deposition disease. Case Report: A 42-year-old female patient is presented with golf ball sized painless swellings in the posterior aspect of her elbows. Elbow joints were clinically normal except for restriction of terminal flexion. X-ray showed mild erosion at the tip of olecranon. Excision biopsy of the swelling showed positive birefringent calcium pyrophosphate dehydrate crystals on the inner wall of the specimen on polarized light microscopy. Conclusion: Bilateral olecranon bursitis may be part of the extraarticular manifestations of calcium pyrophosphate dihydrate crystal deposition disease with good prognosis following in toto bursa excision. PMID:27298934

  19. Bilateral Olecranon Bursitis - A Rare Clinical presentation of Calcium Pyrophosphate Crystal Deposition Disease.

    Science.gov (United States)

    Patel, Jignesh; Girishkumar; Mruthyunjaya; Rupakumar, C S

    2014-01-01

    Calcium pyrophosphate crystal deposition disease (CPPD) is the most common form of crystal arthropathy second only to gout. Common clinical presentation is an acute monoarticular arthritis commonly occurring in knee joints. We presented a case of bilateral olecranon bursitis in a calcium pyrophosphate crystal deposition disease. A 42-year-old female patient is presented with golf ball sized painless swellings in the posterior aspect of her elbows. Elbow joints were clinically normal except for restriction of terminal flexion. X-ray showed mild erosion at the tip of olecranon. Excision biopsy of the swelling showed positive birefringent calcium pyrophosphate dehydrate crystals on the inner wall of the specimen on polarized light microscopy. Bilateral olecranon bursitis may be part of the extraarticular manifestations of calcium pyrophosphate dihydrate crystal deposition disease with good prognosis following in toto bursa excision.

  20. Influence of iron on crystallization behavior and thermal stability of the insulating materials - porous calcium silicates

    DEFF Research Database (Denmark)

    Haastrup, Sonja; Yu, Donghong; Yue, Yuanzheng

    2017-01-01

    The properties of porous calcium silicate for high temperature insulation are strongly influenced by impurities. In this work we determine the influence of Fe3+ on the crystallization behavior and thermal stability of hydrothermally derived calcium silicate. We synthesize porous calcium silicate...... by XRD analysis. The thermal stability and compressive strength of the calcium silicates are seriously influenced by the changes of their crystal structure. Linear shrinkage of the reference sample is 1.3% at 1050°C, whereas the sample with Fe/Si =1.0% does by 30.4%. In conclusion, the presence of Fe3......+ modifies the crystal structure of porous calcium silicates, leading to a significant shrinkage in these materials....

  1. Synthesis of some calcium phosphate crystals using the useful biomass for immobilization of microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Kohiruimaki, T, E-mail: kohi@hi-tech.ac.jp [Department of Technology, Hachinohe Institute of Technology, 88-1 Myo-oobiraki, Hachinohe-shi 031-8501 (Japan)

    2011-10-29

    Three sources of biomass generated by primary industry were used as the raw material for the synthesis of calcium phosphate crystals. Phosphoric acid was extracted from burned rice chaff using a 30% nitric acid solution, while scallop shells and gypsum of plasterboard were used as calcium sources. The calcium phosphate crystals were synthesized by a method involving homogeneous precipitation, and the relationship between the composition and shape of the crystals and the pH at the time of the precipitation was investigated. Monetite crystals in a petal form with a diameter ranging from 0.1 to 2 {mu}m were precipitated at pH 2.0, while granular apatite crystals with a mean diameter of 1 {mu}m were precipitated at pH 6.0. We also investigated the ability of the synthesized calcium phosphate crystals to immobilize lactic acid bacteria for practical use in industrial bioreactor. It was determined that monetite crystals with a diameter of 2 {mu}m had the highest ability to fix lactic acid bacteria. The population of lactic acid bacteria was estimated to exceed 1,300 bacteria per crystal surface of 50 {mu}m{sup 2} suggesting that these crystals may be of practical use in industrial fermenters.

  2. A retrospective study of the prevalence of calcium oxalate crystals in veterinary Aspergillus cases.

    Science.gov (United States)

    Payne, Courtney L; Dark, Michael J; Conway, Julia A; Farina, Lisa L

    2017-01-01

    Fungi in the genus Aspergillus are some of the most common fungal pathogens in veterinary species, primarily affecting the respiratory tract. In both human and veterinary cases, calcium oxalate crystals have been documented in sites of Aspergillus infection. Cases in multiple species (16 birds, 15 horses, 5 dogs, 1 ox, and 1 dolphin) were identified that had either positive cultures for Aspergillus sp., or had conidiophores present that could be identified as belonging to the genus Aspergillus. Histologic slides were examined to confirm the presence of oxalate crystals and how often they were identified on the original report. Calcium oxalate deposition was detected in 14 of 38 cases examined, including A. fumigatus, A. versicolor, A. niger, and unspecified Aspergillus sp. infections. Calcium oxalate crystals were identified in 11 of 16 avian cases, as well as in 1 of 1 bovine, 1 of 15 equine, and 1 of 5 canine cases. Crystals were described in only 3 of the 14 original pathology reports of these cases, indicating that identification and reporting of crystals in histologic specimens could be improved. All the tissues with crystals were respiratory tissues with air interfaces, including nasal sinus, trachea, syrinx, lung, and air sac. In cases with crystals identified on H&E-stained sections, crystals were frequently not present or were fewer in number in tissue sections stained with Gomori methenamine silver and periodic acid-Schiff. Routine polarization of slides of fungal infections, especially in the respiratory tract, should be considered to check for calcium oxalate crystals.

  3. Reinjury risk of nano-calcium oxalate monohydrate and calcium oxalate dihydrate crystals on injured renal epithelial cells: aggravation of crystal adhesion and aggregation.

    Science.gov (United States)

    Gan, Qiong-Zhi; Sun, Xin-Yuan; Bhadja, Poonam; Yao, Xiu-Qiong; Ouyang, Jian-Ming

    2016-01-01

    Renal epithelial cell injury facilitates crystal adhesion to cell surface and serves as a key step in renal stone formation. However, the effects of cell injury on the adhesion of nano-calcium oxalate crystals and the nano-crystal-induced reinjury risk of injured cells remain unclear. African green monkey renal epithelial (Vero) cells were injured with H2O2 to establish a cell injury model. Cell viability, superoxide dismutase (SOD) activity, malonaldehyde (MDA) content, propidium iodide staining, hematoxylin-eosin staining, reactive oxygen species production, and mitochondrial membrane potential (Δψm) were determined to examine cell injury during adhesion. Changes in the surface structure of H2O2-injured cells were assessed through atomic force microscopy. The altered expression of hyaluronan during adhesion was examined through laser scanning confocal microscopy. The adhesion of nano-calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) crystals to Vero cells was observed through scanning electron microscopy. Nano-COM and COD binding was quantitatively determined through inductively coupled plasma emission spectrometry. The expression of hyaluronan on the cell surface was increased during wound healing because of Vero cell injury. The structure and function of the cell membrane were also altered by cell injury; thus, nano-crystal adhesion occurred. The ability of nano-COM to adhere to the injured Vero cells was higher than that of nano-COD crystals. The cell viability, SOD activity, and Δψm decreased when nano-crystals attached to the cell surface. By contrast, the MDA content, reactive oxygen species production, and cell death rate increased. Cell injury contributes to crystal adhesion to Vero cell surface. The attached nano-COM and COD crystals can aggravate Vero cell injury. As a consequence, crystal adhesion and aggregation are enhanced. These findings provide further insights into kidney stone formation.

  4. Crystal structure of calcium dinickel(II iron(III tris(orthophosphate: CaNi2Fe(PO43

    Directory of Open Access Journals (Sweden)

    Said Ouaatta

    2017-06-01

    Full Text Available The title compound, CaNi2Fe(PO43, was synthesized by solid-state reactions. Its structure is closely related to that of α-CrPO4 in the space group Imma. Except for two O atoms in general positions, all atoms are located in special positions. The three-dimensional framework is built up from two types of sheets extending parallel to (100. The first sheet is made up from two edge-sharing [NiO6] octahedra, leading to the formation of [Ni2O10] double octahedra that are connected to two PO4 tetrahedra through a common edge and corners. The second sheet results from rows of corner-sharing [FeO6] octahedra and PO4 tetrahedra forming an infinite linear chain. These layers are linked together through common corners of PO4 tetrahedra and [FeO6] octahedra, resulting in an open three-dimensional framework that delimits two types of channels parallel to [100] and [010] in which the eightfold-coordinated CaII cations are located.

  5. Crystal structure of calcium dinickel(II) iron(III) tris-(orthophosphate): CaNi2Fe(PO4)3.

    Science.gov (United States)

    Ouaatta, Said; Assani, Abderrazzak; Saadi, Mohamed; El Ammari, Lahcen

    2017-06-01

    The title compound, CaNi2Fe(PO4)3, was synthesized by solid-state reactions. Its structure is closely related to that of α-CrPO4 in the space group Imma. Except for two O atoms in general positions, all atoms are located in special positions. The three-dimensional framework is built up from two types of sheets extending parallel to (100). The first sheet is made up from two edge-sharing [NiO6] octa-hedra, leading to the formation of [Ni2O10] double octa-hedra that are connected to two PO4 tetra-hedra through a common edge and corners. The second sheet results from rows of corner-sharing [FeO6] octa-hedra and PO4 tetra-hedra forming an infinite linear chain. These layers are linked together through common corners of PO4 tetra-hedra and [FeO6] octa-hedra, resulting in an open three-dimensional framework that delimits two types of channels parallel to [100] and [010] in which the eightfold-coordinated Ca(II) cations are located.

  6. A new crystallization process in polypropylene highly filled with calcium carbonate

    NARCIS (Netherlands)

    Schawe, Jurgen E.K.; Vermeulen, Paul A.; van Drongelen, Martin

    2015-01-01

    The influence of high amounts of calcium carbonate filler on the crystallization behavior of polypropylene (PP) is investigated by differential scanning calorimetry (DSC) and fast scanning DSC measurements. The non-isothermal crystallization process at industrially relevant cooling rates of about

  7. Feasibility of a tetracycline-binding method for detecting synovial fluid basic calcium phosphate crystals.

    Science.gov (United States)

    Rosenthal, Ann K; Fahey, Mark; Gohr, Claudia; Burner, Todd; Konon, Irina; Daft, Laureen; Mattson, Eric; Hirschmugl, Carol; Ryan, Lawrence M; Simkin, Peter

    2008-10-01

    Basic calcium phosphate (BCP) crystals are common components of osteoarthritis (OA) synovial fluid. Progress in understanding the role of these bioactive particles in clinical OA has been hampered by difficulties in their identification. Tetracyclines stain calcium phosphate mineral in bone. The aim of this study was to investigate whether tetracycline staining might be an additional or alternative method for identifying BCP crystals in synovial fluid. A drop of oxytetracycline was mixed with a drop of fluid containing synthetic or native BCP, calcium pyrophosphate dihydrate (CPPD), or monosodium urate (MSU) crystals and placed on a microscope slide. Stained and unstained crystals were examined by light microscopy, with and without a portable broad-spectrum ultraviolet (UV) pen light. A small set of characterized synovial fluid samples were compared by staining with alizarin red S and oxytetracycline. Synthetic BCP crystals in synovial fluid were quantified fluorimetrically using oxytetracycline. After oxytetracycline staining, synthetic and native BCP crystals appeared as fluorescent amorphous aggregates under UV light. Oxytetracycline did not stain CPPD or MSU crystals or other particulates. Oxytetracycline staining had fewer false-positive test results than did alizarin red S staining and could provide estimates of the quantities of synthetic BCP crystals in synovial fluid. With further validation, oxytetracycline staining may prove to be a useful adjunct or alternative to currently available methods for identifying BCP crystals in synovial fluid.

  8. Mediation of calcium oxalate crystal growth on human kidney epithelial cells with different degrees of injury

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shen [Graduate School of Southern Medical University, Guangzhou 510515 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Su Zexuan, E-mail: suz2008@126.com [The First Affiliated Hospital, Jinan University, Guangzhou 510632 (China); Yao Xiuqiong; Peng Hua; Deng Suiping [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Ouyang Jianming, E-mail: toyjm@jnu.edu.cn [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)

    2012-05-01

    The current study examined the role of injured human kidney tubular epithelial cell (HKC) in the mediation of formation of calcium oxalate (CaOxa) crystals by means of scanning electronic microscopy and X-ray diffraction. HKC was injured using different concentrations of H{sub 2}O{sub 2}. Cell injury resulted in a significant decrease in cell viability and superoxide dismutase (SOD) concentration and an increase in the level of malondialdehyde (MDA) and expression of osteopontin (OPN). Injured cells not only promote nucleation and aggregation of CaOxa crystals, but also induce the formation of calcium oxalate monohydrate (COM) crystals that strongly adhere to cells. These results imply that injured HKCs promote stone formation by providing more nucleating sites for crystals, promoting the aggregation of crystals, and inducing the formation of COM crystals. - Graphical abstract: Injured cells promote nucleation and aggregation of CaOxa crystals, induce the formation of calcium oxalate monohydrate (COM) crystals. Highlights: Black-Right-Pointing-Pointer A direct nucleation and growth of CaOxa crystals on both normal and injured cells. Black-Right-Pointing-Pointer Stronger green fluorescence, i.e. OPN expression, was seen on the injury cell surface Black-Right-Pointing-Pointer Injured cells promote nucleation and aggregation of CaOxa crystals. Black-Right-Pointing-Pointer Injured cells induce the formation of calcium oxalate monohydrate crystals. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} decrease cell viability in a dose-dependent manner at 0.1-1 mmol/L.

  9. Molecular mechanism of crystallization impacting calcium phosphate cements

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

    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.

  11. Structural, spectral and birefringence studies of semiorganic nonlinear optical single crystal: Calcium5-sulfosalicylate

    Science.gov (United States)

    Shalini, D.; Kalainathan, S.; Ambika, V. Revathi; Hema, N.; Jayalakshmi, D.

    2017-11-01

    Semi-organic nonlinear optical crystal Calcium5-Sulfosalicylate (CA5SS) was grown by slow evaporation solution growth technique. The cell parameters and molecular structure of the grown crystal were studied by single crystal x-ray diffraction analysis. The presence of various functional groups of the grown crystal was confirmed using Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) analysis. UV-Visible spectrum shows that CA5SS crystals have high transmittance in the range of 330-900 nm. The refractive index, birefringence and transient photoluminescence properties of the grown crystal were analyzed. The frequency doubling of the grown crystal (CA5SS) were studied and compared with that of KDP.

  12. Bridgman growth and scintillation properties of calcium tungstate single crystal

    Science.gov (United States)

    Wang, Zhenhai; Jiang, Linwen; Chen, Yaping; Chen, Peng; Chen, Hongbing; Mao, Rihua

    2017-12-01

    CaWO4 single crystal with large size was grown by Bridgman method. The results of transmission spectra show that the transmittance of CaWO4 crystal reaches 79-85% in 320-800 nm wavelength range. The refraction index is near 1.80 in visible and infrared region. CaWO4 crystal shows a broad emission band centered at 424 nm under X-ray excitation and centered at 416 nm under ultraviolet (λex = 280 nm) excitation. The decay kinetics of CaWO4 single crystal shows double-exponential decay with fast decay constant τ1 = 5.4 μs and slow decay constant τ2 = 177.1 μs. The energy resolution of CaWO4 crystal was found to be 31.6% in the net peak of 545.9 channel. Meanwhile, the absolute output is at the lever of 19,000 ± 1000 photons/MeV. The results indicate the scintillator of CaWO4 single crystal has great potential in the applications of high-energy physics and nuclear physics due to its high light output and great energy resolution.

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

    Science.gov (United States)

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

    2015-03-01

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

  14. Peptides of Matrix Gla protein inhibit nucleation and growth of hydroxyapatite and calcium oxalate monohydrate crystals.

    Directory of Open Access Journals (Sweden)

    Maria Goiko

    Full Text Available Matrix Gla protein (MGP is a phosphorylated and γ-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 γ-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: YγEpSHEpSMEpSYELNP, YEpS (YEpSHEpSMEpSYELNP, YGlaS (YγESHESMESYELNP and SK-Gla (MGP43-56: SKPVHγELNRγEACDD 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.

  15. Cloning, purification, crystallization and preliminary crystallographic study of calcium-binding protein 5 from Entamoeba histolytica.

    Science.gov (United States)

    Kumar, Sanjeev; Zaidi, Rana; Gourinath, Samudrala

    2012-12-01

    Entamoeba histolytica is the causative agent of human amoebiasis. Phagocytosis is the major route of food intake by this parasite and is responsible for its virulence. Calcium and calcium-binding proteins play major roles in its phagocytosis. Calcium-binding protein 5 from E. histolytica (EhCaBP5) is a cytoplasmic protein; its expression is very sensitive to serum starvation and it seems to be involved in binding to myosin I. In this study, EhCaBP5 was cloned, expressed in Escherichia coli and purified using affinity and size-exclusion chromatography. The purified protein crystallized in space group C222 and the crystals diffracted to 2 Å resolution. The Matthews coefficient indicated the presence of one molecule in the asymmetric unit, with a VM of 2.35 Å3 Da(-1) and a solvent content of 47.7%.

  16. Crystallization of calcium oxalate dihydrate in a buffered calcium-containing glucose solution by irradiation with non-equilibrium atmospheric pressure plasma

    Science.gov (United States)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Mizuno, Masaaki; Ikehara, Yuzuru; Hori, Masaru

    2017-10-01

    Oxalate was synthesized in the glucose solution by irradiation with non-equilibrium atmospheric pressure plasma (NEAPP), in which the NEAPP plume contacted the solution surface, via the generation of several intermediate organic products such as gluconic acid. A thermodynamically unstable phase of calcium oxalate dihydrate crystallized rapidly during incubation of a NEAPP-irradiated glucose solution that contained calcium ions and was buffered at neutral pH. Longer irradiation times increased the growth rate and the number of seed crystals.

  17. Crystal phases of calcium carbonate within otoliths of Cyprinus ...

    African Journals Online (AJOL)

    Significant differences of the dimensions of crystalline cells of vaterites exist between these two localities, which reveals that crystal structure of vaterite polymorphs seem sensitive to water quality and water environment, its crystalline cell dimensions might be a potential proxy for monitoring the change of water quality.

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

    Science.gov (United States)

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

    2008-09-01

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

  19. Degradation of sulfated polysaccharide extracted from algal Laminaria japonica and its modulation on calcium oxalate crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Ouyang Jianming, E-mail: toyjm@jnu.edu.cn [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Wang Miao; Lu Peng; Tan Jin [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)

    2010-08-30

    Sulfated polysaccharide (LPS) extracted from alga Laminaria japonica was degraded by hydrogen peroxide (H{sub 2}O{sub 2}). The average molecular weight of LPS was apparently decreased from 172,000 to 9550 after degradation, while the proportion of sulfate groups (-OSO{sub 3}{sup -}) and carboxylic groups (-COO{sup -}) in the molecular chains of LPS were slightly decreased from 4.5% and 5.20% to 3.9% and 4.64%, respectively. The effects of degraded and natural LPS on formation of calcium oxalate (CaOxa) crystals were investigated in vitro using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), zeta-potential, and atomic absorption spectroscopy. LPS could increase the concentration of soluble Ca{sup 2+} ions in the solution, decrease the weight of precipitated CaOxa, and increase the negative value of zeta-potential of CaOxa crystals. LPS also inhibits the formation of thermodynamically stable calcium oxalate monohydrate (COM) crystals, while inducing and stabilizing metastable calcium oxalate dihydrate (COD) crystals. These results suggested that both degraded and natural LPS could decrease CaOxa crystallization, but the inhibition efficiency of the degraded LPS was clearly superior to that of the natural LPS. We expected this investigation would provide encouragement for further exploration into new drugs for the prevention and treatment of urolithiasis.

  20. Mineralization Process of Biocemented Sand and Impact of Bacteria and Calcium Ions Concentrations on Crystal Morphology

    Directory of Open Access Journals (Sweden)

    Guobin Xu

    2017-01-01

    Full Text Available Microbial-induced calcite precipitation (MICP is a sustainable technique used to improve sandy soil. Analysis of the mineralization process, as well as different bacterial suspensions and calcium concentrations on the crystal morphology, revealed that the mineralization process included four stages: self-organised hydrolysis of microorganisms, molecular recognition and interface interaction, growth modulation, and epitaxial growth. By increasing bacterial suspensions and calcium concentrations, the crystal morphology changed from hexahedron to oblique polyhedron to ellipsoid; the best crystal structure occurs at OD600 = 1.0 and [Ca2+] = 0.75 mol/l. It should be noted that interfacial hydrogen bonding is the main force that binds the loose sand particles. These results will help in understanding the mechanism of MICP.

  1. Investigation of organic desulfurization additives affecting the calcium sulfate crystals formation

    Directory of Open Access Journals (Sweden)

    Lv Lina

    2017-01-01

    Full Text Available In the study, the optimal experimental conditions for gypsum crystals formation were 323 K, 300 rpm stirring speed. The major impurities of Mg2+, Al3+ and Fe3+ were found to inhibit calcium sulfate crystals formation. Fe3+ caused the strongest inhibition, followed by Mg2+ and Al3+. The influence of desulfurization additives on the gypsum crystals formation was explored with the properties of moisture content, particle size distribution and crystal morphology. The organic desulfurization additives of adipic acid, citric acid, sodium citrate and benzoic acid were investigated. Citric acid and sodium citrate were found to improve the quality of gypsum. Moisture contents were reduced by more than 50%, gypsum particle sizes were respectively enlarged by 9.1 and 22.8%, induction time extended from 4.3 (blank to 5.3 and 7.8 min, and crystal morphology trended to be thicker.

  2. Crystal structure of metagenomic β-xylosidase/ α-l-arabinofuranosidase activated by calcium.

    Science.gov (United States)

    Matsuzawa, Tomohiko; Kaneko, Satoshi; Kishine, Naomi; Fujimoto, Zui; Yaoi, Katsuro

    2017-09-01

    The crystal structure of metagenomic β-xylosidase/α-l-arabinofuranosidase CoXyl43, activated by calcium ions, was determined in its apo and complexed forms with xylotriose or l-arabinose in the presence and absence of calcium. The presence of calcium ions dramatically increases the kcat of CoXyl43 for p-nitrophenyl β-d-xylopyranoside and reduces the Michaelis constant for p-nitrophenyl α-l-arabinofuranoside. CoXyl43 consists of a single catalytic domain comprised of a five-bladed β-propeller. In the presence of calcium, a single calcium ion was observed at the centre of this catalytic domain, behind the catalytic pocket. In the absence of calcium, the calcium ion was replaced with one sodium ion and one water molecule, and the positions of these cations were shifted by 1.3 Å. The histidine-319 side chain, which coordinates to the 2-hydroxyl oxygen atom of the bound xylose molecule in the catalytic pocket, also coordinates to the calcium ion, but not to the sodium ion. The calcium-dependent increase in activity appears to be caused by the structural change in the catalytic pocket induced by the tightly bound calcium ion and coordinating water molecules, and by the protonation state of glutamic acid-268, the catalytic acid of the enzyme. Our findings further elucidate the complex relationship between metal ions and glycosidases. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

  3. Biomimetic Calcium Phosphate Crystallization: Synchrotron X-ray Studies

    Science.gov (United States)

    Uysal, Ahmet; Stripe, Benjamin; Dutta, Pulak; Lin, Binhua; Meron, Mati

    2012-02-01

    The nucleation and growth of calcium phosphate by organic templates attract great attention due to its relevance to bone biomineralization. In spite of the vast studies in the field, the role of the organic templates in the process is still not well understood. One reason for this drawback is the lack of experimental tools to probe the organic template structure during the process. We studied the nucleation and growth of calcium phosphate under floating Langmuir monolayers, at the air/water interface, using two complementary X-ray scattering methods. We show that Grazing Incidence X-ray Diffraction (GID) and Grazing Incidence X-ray off-Specular Scattering (GIXOS) can reveal the organic-inorganic interface properties in situ. By using GID and GIXOS together, we can simultaneously determine the lateral interface structure and the electron density profile normal to the interface. Combined with ex situ methods, these techniques can improve our understanding of the role of the organic template during biomineralization.

  4. Why Basic Calcium Phosphate Crystals Should Be Targeted In the Treatment of Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Claire-Louise Murphy

    2014-07-01

    Full Text Available Osteoarthritis (OA is the most common form of arthritis and results in significant social, psychological, and economic costs. It is characterised by progressive cartilage loss, bone remodelling, osteophyte formation, and synovial inflammation with resultant joint pain and disability. Since OA affects the entire joint, it is not surprising that there has been difficulty developing an effective targeted treatment. Treatments available for structural disease modification are limited. Current options appear to mostly reduce symptoms. Basic calcium phosphate (BCP crystals represent a potential therapeutic target in OA; they have been found in 100% of knee and hip cartilages removed at joint replacement. Intra-articular BCP crystals are associated with large joint effusions and dissolution of intra-articular structures, synovial proliferation, and marked degeneration as assessed by diagnostic imaging. While BCP deposition has been considered by many to be simply a consequence of advanced OA, there is substantial evidence to support BCP crystal deposition as an active pathogenic mediator of OA. BCP crystals exhibit a multiplicity of biologic effects in vitro including the ability to stimulate mitogenesis and prostaglandin, cytokine, and matrix metalloproteinase (MMP synthesis in a number of cell types including macrophages, synovial fibroblasts, and chondrocytes. BCP crystals also contribute to inflammation in OA through direct interaction with the innate immune system. Intra-articular BCP crystals can elicit synovial inflammation and cartilage degradation in mice in vivo . Although intra-articular BCP crystals are difficult to detect at the bedside, advances in modern technology should allow improved identification and quantitation of BCP crystals. Our article focuses on why basic calcium crystals are important in the pathogenesis of OA. There is ample evidence that BCP crystals should be explored as a therapeutic target in OA.

  5. Growth Rate and Morphology of a Single Calcium Carbonate Crystal on Polysulfone Film Measured with Time Lapse Raman Micro Spectroscopy

    NARCIS (Netherlands)

    Liszka, B.; Lenferink, Aufrid T.M.; Otto, Cornelis

    2016-01-01

    The growth of single, self- nucleated calcium carbonate crystals on a polysulfone (PSU) film was investigated with high resolution, time lapse Raman imaging. The Raman images were acquired on the interface of the polymer with the crystal. The growth of crystals could thus be followed in time. PSU is

  6. Calcium oxalate crystals: an integral component of the Sclerotinia sclerotiorum/Brassica carinata pathosystem.

    Science.gov (United States)

    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 (sclerotiorum growth and infection controls the form taken by CaOx crystals.

  7. The Bridgman method growth and spectroscopic characterization of calcium fluoride single crystals

    Directory of Open Access Journals (Sweden)

    Elswie Ibrahim Hana

    2016-01-01

    Full Text Available It must be noted that the main objective of this study was to obtain single crystals of calcium fluoride - CaF2, and after that the crystals were characterized with various spectroscopic methods. The crystals were grown using the Bridgman technique. By optimizing growth conditions, oriented CaF2 crystals up to 20 mm in diameter were grown. Number of dislocations in CaF2 crystals was 5×104 - 2×105 per cm2. Selected CaF2 single crystal is cut into several tiles with the diamond saw. The plates were polished, first with the silicon carbide, then the paraffin oil, and finally with a diamond paste. The obtained crystal wаs studied by Raman and infrared -IR spectroscopy. The crystal structure is confirmed by X-ray diffraction (XRD. One Raman and two IR optical modes predicted by group theory are observed. A low photoluminescence testifies that the concentration of oxygen defects within the host CaF2 is small. All performed investigations show that the obtained CaF2 single crystal has good optical quality, which was the goal of this work. [Projekat Ministarstva nauke Republike Srbije, br. III 45003 i br. TR34011

  8. Effect calcusol to reduce the calcium crystal retention in kidney epithelial cells model of nephrolothiasis

    Directory of Open Access Journals (Sweden)

    Ahmad Soni

    2014-12-01

    Full Text Available Kidney stones is a disease that characterized by a disturbance in the bladder. The main constituent of kidney stones namely Calcium Oxalate Monohydrate (COM crystals. The presence of a COM crystal adhesion to renal tubular cells, will initiate the internalization which will further lead to the formation of crystals retention in the kidney. In Indonesia, there are many herbal products are considered able to cope the complaints due to the kidney stone disease. One of the herbal product is Calcusol „¢, which is the main constituent of those herbal product was the leaf extract of tempuyung. This study observed the effectiveness of Calcusol „¢ in reducing crystals retention that was formed in kidney epithelial cells model of nephrolithiasis. The result showed that Calcusol „¢ is able to reduce the average number of calcium crystals retention in the renal epithelial cells. It indicate that Calcusol „¢ has the ability to reduce crystals retention that already formed in renal epithelial cells. Furthermore, the results of this study are expected to be one of the considerations for further research on the potential of overcoming Calcusol „¢ in kidney stone disease

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

    Science.gov (United States)

    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.

  10. Mechanism of calcium phosphates precipitation in liquid crystals; Mecanisme de precipitation de phosphates de calcium dans des cristaux liquides

    Energy Technology Data Exchange (ETDEWEB)

    Prelot, B.; Zemb, T

    2004-04-01

    The possibility of using as a precursor an easily wet meso-porous powder would be a breakthrough in the preparation of nuclear waste storage ceramics. A concentrated solution containing ions to be stored would wet a dry powder and then, subjected to mild compression, lead to a micro-crystalline matrix of calcium phosphate at acceptable temperatures. Since no porous calcium phosphate different from calcined bone (patented) is described as porous precursor, we have compared the different synthesis routes towards meso-porous ceramics. First, we considered homogeneous precipitation of slats in water: using initially off-stoichiometry in reaction, micron-sized hydroxyapatite particles are produced with a specific surface up to 100 m{sup 2}/g. Then, we consider the classical route of precipitation of an hybrid material in the miscibility gap of a phase diagram, when an hexagonal liquid crystal is used a matrix for precipitation. The surfactant family consists in single chain surfactants containing phosphates as head-group to poison the growing surface of calcium phosphate nano-domains. Since the reaction is still too brutal, we considered using a cat-anionic precursor material of controllable surface charge. For certain concentrations and molar ratios, a new structure not yet described in surfactant precipitation literature is observed: since the periodicity is lower than twice the chain length, a disordered constant curvature monolayer (instead of the classical cylinder of twice chain length diameter) of surfactant is implied. Finally, we have investigated synthesis routes implying slow dissolution of pre-formed calcium phosphate in an already existing hexagonal matrix. For all these routes of synthesis, micro-structural determinations using SAXS, WARS and BET are performed, with a special attention to comparison of the precipitation material, the matrix obtained with all elements present, and also the material obtained after calcinations. (authors)

  11. Calcium pyrophosphate dihydrate crystal deposition disease presenting as a pseudotumor of the temporomandibular joint

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, A.; Teruel, J.; Pont, J.; Velayos, A. [Department of Radiology, Hospital de Girona ``Dr. Josep Trueta``, Av. de Franca s/n, E-17 007 Girona (Spain); Trull, J. [Department of Oral Surgery, Hospital de Girona, Dr. ``Josep Trueta``, Av. de Franca s/n, E-17 007 Girona (Spain); Lopez, E. [Department of Pathology, Hospital de Girona, Dr. ``Josep Trueta``, Av. de Franca s/n, E-17 007 Girona (Spain)

    1997-12-01

    We report a case of a 66-year-old white woman with calcium pyrophosphate dihydrate (CPPD) crystal deposition disease. The patient related a 2-month history of swelling with tenderness over the left pre-auricular region. A CT scan suggested a synovial chondromatosis. Surgical removal was done and histologic study showed CPPD crystals. This disease rarely involves the temporomandibular joint (TMJ) and is not usually considered in the differential diagnosis. To our knowledge, only 14 cases have been reported in the literature. (orig.) With 3 figs., 10 refs.

  12. INHIBITION OF CALCIUM OXALATE CRYSTALLIZATION IN-VITRO BY VARIOUS EXTRACTS OF HYPTIS SUAVEOLENS (L.) POIT.

    OpenAIRE

    Agarwal Kumkum; Varma Ranjana

    2012-01-01

    Hyptis suaveolens (L) Poit. commonly known as Vilayati tulsi, belongs to the Mint family Lamiaceae. The inhibition of in-vitro calcium-oxalate crystal (a major component of most urinary stones) formation by various extracts of Hyptis was investigated by titrimetric method. The inhibitor potency of alcohol extracts of Hyptis suaveolens (L.) Poit was found to be comparable to that of cystone (a proprietary drug for dissolving kidney stones). Thus alcohol extract could be further analyzed in viv...

  13. Effects of polymer concentration on the morphology of calcium phosphate crystals formed in polyacrylamide hydrogels

    Science.gov (United States)

    Yokoi, Taishi; Kawashita, Masakazu; Ohtsuki, Chikara

    2013-11-01

    Growing crystals in hydrogels is an attractive method to form inorganic solids with designed morphology under ambient conditions. Precipitation of the inorganic solids in a hydrogel matrix can be regarded as mimicking the process of biomineralization. In the construction of biominerals, an organic template composed of insoluble macromolecules is used to control the crystal growth of the inorganic compounds. The morphological control in biomineralization can be applied to artificial reaction systems. In this study, the morphology of calcium phosphate crystals formed in polymeric hydrogels of various polymer concentrations was investigated. Spherical octacalcium phosphate (OCP) precipitated in the polyacrylamide (PAAm) hydrogels. Fibrous crystals gradually covered the surface of the spherical crystals as the polymer concentration of the gel increased. The morphology of the OCP crystals changed from sea urchin shapes to wool-ball shapes with increasing PAAm concentration. The morphological change is generated by the template effect of the polymer wall, which is made up of stacked PAAm sheets, surrounding the spherical OCP crystals.

  14. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  15. Electron paramagnetic resonance and luminescence of chromium in calcium germanate crystals

    CERN Document Server

    Gorshkov, O N; Tyurin, S A; Chigineva, A B; Chigirinskij, Y I

    2002-01-01

    One observed luminescence of Cr sup 4 sup + :Ca sub 2 GeO sub 4 single crystals near 1.3 mu m wave length at excitation by a semiconducting laser up to 573 K. At T < 110 K one detected the EPR spectrum identified as one belonging to Cr sup 4 sup + ions substituting for germanium. One determined the components of g-tensor and its basic axes. In calcium germanate this impurity centre slightly violates crystal symmetry. Detected deviation from the Curie law in EPR temperature dependence is explained by transition into the excited state with activation low energy. The giant efficient multiplicity of degeneration of the excited state is explained by induction of soft phonon modes of crystal at excitation of a defect

  16. Effect of Hydraulic Activity on Crystallization of Precipitated Calcium Carbonate (PCC for Eco-Friendly Paper

    Directory of Open Access Journals (Sweden)

    Hwan Kim

    2009-11-01

    Full Text Available Wt% of aragonite, a CaCO3 polymorph, increased with higher hydraulic activity (°C of limestone in precipitated calcium carbonate (PCC from the lime-soda process (Ca(OH2-NaOH-Na2CO3. Only calcite, the most stable polymorph, was crystallized at hydraulic activity under 10 °C, whereas aragonite also started to crystallize over 10 °C. The crystallization of PCC is more dependent on the hydraulic activity of limestone than CaO content, a factor commonly used to classify limestone ores according to quality. The results could be effectively applied to the determination of polymorphs in synthetic PCC for eco-friendly paper manufacture.

  17. Role of Tamm-Horsfall protein and uromodulin in calcium oxalate crystallization

    Directory of Open Access Journals (Sweden)

    Carvalho M.

    2002-01-01

    Full Text Available One of the defenses against nephrolithiasis is provided by macromolecules that modulate the nucleation, growth, aggregation and retention of crystals in the kidneys. The aim of the present study was to determine the behavior of two of these proteins, Tamm-Horsfall and uromodulin, in calcium oxalate crystallization in vitro. We studied a group of 10 male stone formers who had formed at least one kidney stone composed of calcium oxalate. They were classified as having idiopathic nephrolithiasis and had no well-known metabolic risk factors involved in kidney stone pathogenesis. Ten normal men were used as controls, as was a group consisting of five normal women and another consisting of five pregnant women. Crystallization was induced by a fixed supersaturation of calcium oxalate and measured with a Coulter Counter. All findings were confirmed by light and scanning electron microscopy. The number of particulate material deposited from patients with Tamm-Horsfall protein was higher than that of the controls (P<0.001. However, Tamm-Horsfall protein decreased the particle diameter of the stone formers when analyzed by the mode of the volume distribution curve (P<0.002 (5.64 ± 0.55 µm compared to 11.41 ± 0.48 µm of uromodulin; 15.94 ± 3.93 µm and 12.45 ± 0.97 µm of normal men Tamm-Horsfall protein and uromodulin, respectively; 8.17 ± 1.57 µm and 9.82 ± 0.95 µm of normal women Tamm-Horsfall protein and uromodulin, respectively; 12.17 ± 1.41 µm and 12.99 ± 0.51 µm of pregnant Tamm-Horsfall protein and uromodulin, respectively. Uromodulin produced fewer particles than Tamm-Horsfall protein in all groups. Nonetheless, the total volume of the crystals produced by uromodulin was higher than that produced by Tamm-Horsfall protein. Our results indicate a different effect of Tamm-Horsfall protein and uromodulin. This dual behavior suggests different functions. Tamm-Horsfall protein may act on nucleation and inhibit crystal aggregation, while

  18. Transformation and Crystallization Energetics of Synthetic and Biogenic Amorphous Calcium Carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Radha, A. V. [Peter A. Rock Thermochemistry Lab. and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Univ. of California, Davis, CA (United States); Forbes, Tori Z. [Peter A. Rock Thermochemistry Lab. and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Univ. of California, Davis, CA (United States); Killian, Christopher E. [Univ. of Wisconsin, Madison, WI (United States); Gilbert, P.U.P.A [Univ. of Wisconsin, Madison, WI (United States); Navrotsky, Alexandra [Peter A. Rock Thermochemistry Lab. and Nanomaterials in the Environment, Agriculture, and Technology Organized Research Unit (NEAT ORU), Univ. of California, Davis, CA (United States)

    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.

  19. Defining and Systematic Analyses of Aggregation Indices to Evaluate Degree of Calcium Oxalate Crystal Aggregation

    Directory of Open Access Journals (Sweden)

    Sakdithep Chaiyarit

    2017-12-01

    Full Text Available Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM crystals with various concentrations (25–800 μg/ml in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant. The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r = 0.997; p < 0.001, whereas the equally second rank included aggregated mass index and optical density (r = 0.993; p < 0.001 and r = −0.993; p < 0.001, respectively and the equally forth were aggregation coefficient and span (r = 0.991; p < 0.001 for both. These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

  20. Defining and Systematic Analyses of Aggregation Indices to Evaluate Degree of Calcium Oxalate Crystal Aggregation.

    Science.gov (United States)

    Chaiyarit, Sakdithep; Thongboonkerd, Visith

    2017-01-01

    Crystal aggregation is one of the most crucial steps in kidney stone pathogenesis. However, previous studies of crystal aggregation were rarely done and quantitative analysis of aggregation degree was handicapped by a lack of the standard measurement. We thus performed an in vitro assay to generate aggregation of calcium oxalate monohydrate (COM) crystals with various concentrations (25-800 μg/ml) in saturated aggregation buffer. The crystal aggregates were analyzed by microscopic examination, UV-visible spectrophotometry, and GraphPad Prism6 software to define a total of 12 aggregation indices (including number of aggregates, aggregated mass index, optical density, aggregation coefficient, span, number of aggregates at plateau time-point, aggregated area index, aggregated diameter index, aggregated symmetry index, time constant, half-life, and rate constant). The data showed linear correlation between crystal concentration and almost all of these indices, except only for rate constant. Among these, number of aggregates provided the greatest regression coefficient (r = 0.997; p < 0.001), whereas the equally second rank included aggregated mass index and optical density (r = 0.993; p < 0.001 and r = -0.993; p < 0.001, respectively) and the equally forth were aggregation coefficient and span (r = 0.991; p < 0.001 for both). These five indices are thus recommended as the most appropriate indices for quantitative analysis of COM crystal aggregation in vitro.

  1. Characterization of an additional articular cartilage vesicle fraction that generates calcium pyrophosphate dihydrate crystals in vitro.

    Science.gov (United States)

    Derfus, B; Steinberg, M; Mandel, N; Buday, M; Daft, L; Ryan, L

    1995-08-01

    We previously identified a unique fraction of porcine articular cartilage vesicles, sedimentable at 8 x 10(6) g/min, which generate calcium pyrophosphate dihydrate crystals (CPPD) in vitro. We sought to identify and characterize other fractions of articular cartilage digest, sedimentable at lower g forces, which may also contain mineralizing vesicles. Electron microscopy and alkaline phosphatase and nucleoside triphosphate pyrophosphohydrolase (NTPPPH) assays were used to analyze each fraction. Radiometric mineralization assays, Fourier transform infrared (FTIR) spectroscopy, and compensated polarized light microscopy were used to analyze crystals formed by these fractions. Vesicles of varying sizes identical to epiphyseal cartilage matrix vesicles were seen in all sedimentable fractions examined, but were the exclusive component of fractions sedimentable at 3 x 10(6) g/min, termed the heavy vesicle fraction (HVF), and at 8 x 10(6) g/min, now termed the light vesicle fraction (LVF). All vesicle containing fractions supported ATP dependent calcium pyrophosphate precipitation. The HVF and LVF precipitated 30 x more calcium than vesicle poor supernatant (p < 0.01) and 1.5-4 x more than cell-free unfractionated digest (p < 0.01). HVF differed from LVF in that it contained 3-4 x higher NTPPPH specific activity (p < 0.05). HVF resembled LVF in that both precipitated crystals consistent with CPPD by FTIR spectroscopy and compensated polarized light microscopy. These data expand our previous estimate of the total number of vesicles available for biologic mineralization and demonstrate heterogeneity of vesicle fractions. They support a key role for vesicles in CPPD crystal formation.

  2. Qualitative discussion of prenucleation cluster role in crystallization of calcium carbonate under high concentration of magnesium based on experimental phenomena

    Science.gov (United States)

    Zhang, Jie; Sun, Yuzhu; Yu, Jianguo

    2017-11-01

    Crystallization of calcium carbonate under high concentration of magnesium was studied. Interesting phenomena were observed. Approximately 80% of calcium ions stably existed in the solution up to 60 min after amorphous calcium carbonate was separated by centrifugation, and induction time was significantly affected by concentration and feeding rate of sodium carbonate when other operating conditions remained unchanged. Experiments and computer simulation have proved that prenucleation cluster exists during crystallization of calcium carbonate in solutions. This paper tried to figure out specific crystallization process of calcium carbonate under high concentration of magnesium, and to interpret unforeseen phenomena combining with the idea of prenucleation cluster. With regarding prenucleation cluster which can incorporate magnesium into its structure as amorphous calcium carbonate, most of the phenomena including significant influence of local mixing could be better understood. Prenucleation cluster played an important role in crystallization of calcium carbonate, which was related to the induction time, morphology and final product, thus more fundamental studies of prenucleation cluster structure and magnesium role in it should be done.

  3. The influence of freezer storage of urine samples on the BONN-Risk-Index for calcium oxalate crystallization.

    Science.gov (United States)

    Laube, Norbert; Zimmermann, Diana J

    2004-01-01

    This study was performed to quantify the effect of a 1-week freezer storage of urine on its calcium oxalate crystallization risk. Calcium oxalate is the most common urinary stone material observed in urolithiasis patients in western and affluent countries. The BONN-Risk-Index of calcium oxalate crystallization risk in human urine is determined from a crystallization experiment performed on untreated native urine samples. We tested the influence of a 1-week freezing on the BONN-Risk-Index value as well as the effect of the sample freezing on the urinary osmolality. In vitro crystallization experiments in 49 native urine samples from stone-forming and non-stone forming individuals were performed in order to determine their calcium oxalate crystallization risk according to the BONN-Risk-Index approach. Comparison of the results derived from original sample investigations with those obtained from the thawed aliquots by statistical evaluation shows that i) no significant deviation from linearity between both results exists and ii) both results are identical by statistical means. This is valid for both, the BONN-Risk-Index and the osmolality data. The differences in the BONN-Risk-Index results of both procedures of BONN-Risk-Index determination, however, exceed the clinically acceptable difference. Thus, determination of the urinary calcium oxalate crystallization risk from thawed urine samples cannot be recommended.

  4. Free DNA precipitates calcium phosphate apatite crystals in the arterial wall in vivo.

    Science.gov (United States)

    Coscas, Raphaël; Bensussan, Marie; Jacob, Marie-Paule; Louedec, Liliane; Massy, Ziad; Sadoine, Jeremy; Daudon, Michel; Chaussain, Catherine; Bazin, Dominique; Michel, Jean-Baptiste

    2017-04-01

    The arterial wall calcium score and circulating free DNA levels are now used in clinical practice as biomarkers of cardiovascular risk. Calcium phosphate apatite retention in the arterial wall necessitates precipitation on an anionic platform. Here, we explore the role of tissue-free DNA as such a platform. The first step consisted of histological observation of samples from human and rat calcified arteries. Various stains were used to evaluate colocalization of free DNA with calcified tissue (alizarin red, fluorescent Hoechst, DNA immunostaining and TUNEL assay). Sections were treated by EDTA to reveal calcification background. Secondly, a rat model of vascular calcifications induced by intra-aortic infusions of free DNA and elastase + free DNA was developed. Rat aortas underwent a micro-CT for calcium score calculation at 3 weeks. Rat and human calcifications were qualitatively characterized using μFourier Transform Infrared Spectroscopy (μFTIR) and Field Emission-Scanning Electron Microscopy (FE-SEM). Our histological study shows colocalization of calcified arterial plaques with free DNA. In the intra-aortic infusion model, free DNA was able to penetrate into the arterial wall and induce calcifications whereas no microscopic calcification was seen in control aortas. The calcification score in the elastase + free DNA group was significantly higher than in the control groups. Qualitative evaluation with μFTIR and FE-SEM demonstrated typical calcium phosphate retention in human and rat arterial specimens. This translational study demonstrates that free DNA could be involved in arterial calcification formation by precipitating calcium phosphate apatite crystals in the vessel wall. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. EPR and optical absorption studies on VO 2+ ions in calcium fumarate trihydrate single crystals

    Science.gov (United States)

    Kripal, Ram; Mishra, Indrajeet; Gupta, S. K.; Arora, Manju

    2010-01-01

    Electron Paramagnetic Resonance (EPR) studies of VO 2+ ions in calcium fumarate trihydrate single crystals have been done at room temperature. EPR analysis indicates the presence of two magnetically inequivalent VO 2+ sites. For the two sites the spin Hamiltonian parameters are, Site I: g x = 1.9689 ,g y = 2.0087 ,g z = 1.9344, A x = 73 ,A y = 88 ,A z = 202; Site II: g x = 1.9675 ,g y = 2.0100 ,g z = 1.9346 ,A x = 75 ,A y = 90, A z = 206 (×10 -4) cm -1. The optical absorption study is also carried out at room temperature. By correlating EPR and optical data the nature of bonding in the crystal is discussed. The three-line superhyperfine structure has been attributed to two protons.

  6. Modulation of calcium oxalate monohydrate crystallization by citrate through selective binding to atomic steps

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-10-19

    The majority of human kidney stones are composed primarily of calcium oxalate monohydrate (COM) crystals. Thus, determining the molecular mechanisms by which urinary constituents modulate calcium oxalate crystallization is crucial for understanding and controlling urolithiassis in humans. A comprehensive molecular-scale view of COM shape modification by citrate, a common urinary constituent, obtained through a combination of in situ atomic force microscopy (AFM) and molecular modeling is now presented. We show that citrate strongly influences the growth morphology and kinetics on the (-101) face but has much lower effect on the (010) face. Moreover, binding energy calculations show that the strength of the citrate-COM interaction is much greater at steps than on terraces and is highly step-specific. The maximum binding energy, -166.5 kJ {center_dot} mol{sup -1}, occurs for the [101] step on the (-101) face. In contrast, the value is only -56.9 kJ {center_dot} mol-1 for the [012] step on the (010) face. The binding energies on the (-101) and (010) terraces are also much smaller, -65.4 and -48.9 kJ {center_dot} mol{sup -1} respectively. All other binding energies lie between these extremes. This high selectivity leads to preferential binding of citrate to the acute [101] atomic steps on the (-101) face. The strong citrate-step interactions on this face leads to pinning of all steps, but the anisotropy in interaction strength results in anisotropic reductions in step kinetics. These anisotropic changes in step kinetics are, in turn, responsible for changes in the shape of macroscopic COM crystals. Thus, the molecular scale growth morphology and the bulk crystal habit in the presence of citrate are similar, and the predictions of molecular simulations are fully consistent with the experimental observations.

  7. Thermal Stability and Proton Conductivity of Rare Earth Orthophosphate Hydrates

    DEFF Research Database (Denmark)

    Anfimova, Tatiana; Li, Qingfeng; Jensen, Jens Oluf

    2014-01-01

    Hydrated orthophosphate powders of three rare earth metals, lanthanum, neodymium and gadolinium, were prepared and studied as potential proton conducting materials for intermediate temperature electrochemical applications. The phosphates undergo a transformation from the rhabdophane structure...

  8. L-Carnitine Protects Renal Tubular Cells Against Calcium Oxalate Monohydrate Crystals Adhesion Through Preventing Cells From Dedifferentiation

    Directory of Open Access Journals (Sweden)

    Shujue Li

    2016-08-01

    Full Text Available Background/Aims: The interactions between calcium oxalate monohydrate (COM crystals and renal tubular epithelial cells are important for renal stone formation but still unclear. This study aimed to investigate changes of epithelial cell phenotype after COM attachment and whether L-carnitine could protect cells against subsequent COM crystals adhesion. Methods: Cultured MDCK cells were employed and E-cadherin and Vimentin were used as markers to estimate the differentiate state. AlexaFluor-488-tagged COM crystals were used in crystals adhesion experiment to distinguish from the previous COM attachment, and adhesive crystals were counted under fluorescence microscope, which were also dissolved and the calcium concentration was assessed by flame atomic absorption spectrophotometry. Results: Dedifferentiated MDCK cells induced by transforming growth factor β1 (TGF-β1 shown higher affinity to COM crystals. After exposure to COM for 48 hours, cell dedifferentiation were observed and more subsequent COM crystals could bind onto, mediated by Akt/GSK-3β/Snail signaling. L-carnitine attenuated this signaling, resulted in inhibition of cell dedifferentiation and reduction of subsequent COM crystals adhesion. Conclusions: COM attachment promotes subsequent COM crystals adhesion, by inducing cell dedifferentiation via Akt/GSK-3β/Snail signaling. L-carnitine partially abolishes cell dedifferentiation and resists COM crystals adhesion. L-carnitine, may be used as a potential therapeutic strategy against recurrence of urolithiasis.

  9. A Rare Case of Tumoral Calcium Pyrophosphate Dihydrate Crystal Deposition Disease of the Wrist Joint

    Directory of Open Access Journals (Sweden)

    Osamu Nakamura

    2015-01-01

    Full Text Available Introduction. Tumoral calcium pyrophosphate dihydrate (CPPD crystal deposition disease (CPPDCD, also known as tophaceous calcium pyrophosphate deposition disease (CPDD, is a tumorlike lesion, and it should be distinguished from usual CPDD that causes severe joint inflammation and arthralgia. A case of tumoral CPPDCD of the wrist joint that required differentiation from synovial osteochondromatosis is described. Case Presentation. The patient was a 78-year-old woman with a 5-year history of nodular lesions at the right wrist that had gradually increased in size. An excisional biopsy and a histological examination of the excised nodular lesions by hematoxylin and eosin (H&E staining were performed, demonstrating numerous polarizable, rhabdoid, and rectangular crystals, surrounded by fibroblasts, macrophages, and foreign body-type giant cells, consistent with tumoral CPPDCD. Conclusion. Tumoral CPPDCD, especially at the wrist joint, is rare, and, to the best of our knowledge, only 2 articles have been published. This case seems to need further follow-up for recurrence, because tumoral CPPDCD may recur after complete or incomplete surgical excision.

  10. Influence of acid-soluble proteins from bivalve Siliqua radiata ligaments on calcium carbonate crystal growth

    Science.gov (United States)

    Huang, Zeng-Qiong; Zhang, Gang-Sheng

    2016-08-01

    In vitro biomimetic synthesis of calcium carbonate (CaCO3) in the presence of shell proteins is a heavily researched topic in biomineralization. However, little is known regarding the function of bivalve ligament proteins in the growth of CaCO3 crystals. In this study, using fibrous protein K58 from Siliqua radiata ligaments or coverslips as substrates, we report the results of our study of CaCO3 precipitation in the presence or absence of acid-soluble proteins (ASP) from inner ligament layers. ASP can disturb the controlling function of K58 or a coverslip on the crystalline phase, resulting in the formation of aragonite, calcite, and vaterite. In addition, we identified the following four primary components from ASP by mass spectroscopy: alkaline phosphatase (ALP), ABC transporter, keratin type II cytoskeletal 1 (KRT 1), and phosphate ABC transporter, phosphate-binding protein (PstS). Further analysis revealed that the first three proteins and especially ALP, which is important in bone mineralisation, could affect the polymorphism and morphology of CaCO3 crystals by trapping calcium ions in their domains. Our results indicate that ALP may play an important role in the formation of aragonite in S. radiata ligaments. This paper may facilitate our understanding of the biomineralization process.

  11. Catechin prevents the calcium oxalate monohydrate induced renal calcium crystallization in NRK-52E cells and the ethylene glycol induced renal stone formation in rat

    Science.gov (United States)

    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

  12. Calcium

    Science.gov (United States)

    ... 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 products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  13. Calciphytoliths (calcium oxalate crystals) analysis for the identification of decayed tea plants (Camellia sinensis L.).

    Science.gov (United States)

    Zhang, Jianping; Lu, Houyuan; Huang, Linpei

    2014-10-24

    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 μm), 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.

  14. Calcium pyrophosphate dihydrate and hydroxyapatite crystals in a patient with rheumatoid arthritis: Acase report

    Directory of Open Access Journals (Sweden)

    Shereen R Kamel

    2017-01-01

    Full Text Available The association between rheumatoid arthritis (RA and calcium pyrophosphate dihydrate (CPPD crystal deposits can now be easily identified by MSUS, which is a noninvasive technique that can be applied to patients with painful joints and enthesis that are unexplained by rheumatoid activity. In this paper, we report an Egyptian case of a 51-year-old man who had rheumatoid arthritis since 7 years and developed bilateral knee and heel pain of 1.5 months’ duration with gradual onset and progressive course. Radiography revealed features of RA in both hands, as well as features of severe osteoarthritis in both knees with no signs of chondrocalcinosis. Ultrasonography of the joints, Achilles tendon, and plantar fascia detected knee, Achilles tendon, and plantar fascia calcifications, which are characteristic of CPPD, and supraspinatus calcification, which is characteristic of hydroxyapatite (HA deposition. Further investigations revealed no evidence of metabolic disorders. CPPD and HA crystals were identified in his synovial fluid. Subclinical affection with CPPD and HA crystals in RA can be easily detected by ultrasonography, which allows early management to prevent future attacks in RA patients that could lead to exacerbation of joint symptoms that may be missed as rheumatoid disease activity. Diet control and colchicine treatment may be more effective if started early before exacerbation.

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

    Science.gov (United States)

    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.

  16. An Assessment of Engineered Calcium Oxalate Crystal Formation on Plant Growth and Development as a Step toward Evaluating Its Use to Enhance Plant Defense.

    Science.gov (United States)

    Nakata, Paul A

    2015-01-01

    The establishment of new approaches to control chewing insects has been sought not only for direct use in reducing crop loss but also in managing resistance to the pesticides already in use. Engineered formation of calcium oxalate crystals is a potential strategy that could be developed to fulfill both these needs. As a step toward this development, this study investigates the effects of transforming a non-calcium oxalate crystal accumulating plant, Arabidopsis thaliana, into a crystal accumulating plant. Calcium oxalate crystal accumulating A. thaliana lines were generated by ectopic expression of a single bacterial gene encoding an oxalic acid biosynthetic enzyme. Biochemical and cellular studies suggested that the engineered A. thaliana lines formed crystals of calcium oxalate in a manner similar to naturally occurring crystal accumulating plants. The amount of calcium oxalate accumulated in leaves also reached levels similar to those measured in the leaves of Medicago truncatula in which the crystals are known to play a defensive role. Visual inspection of the different engineered lines, however, suggested a phenotypic consequence on plant growth and development with higher calcium oxalate concentrations. The restoration of a near wild-type plant phenotype through an enzymatic reduction of tissue oxalate supported this observation. Overall, this study is a first to provide initial insight into the potential consequences of engineering calcium oxalate crystal formation in non-crystal accumulating plants.

  17. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  18. Evaluation of calcium hydrogen carbonate mesoscopic crystals as a disinfectant for influenza A viruses.

    Science.gov (United States)

    Nakashima, Ryuji; Kawamoto, Masaomi; Miyazaki, Shigeru; Onishi, Rumiko; Furusaki, Koichi; Osaki, Maho; Kirisawa, Rikio; Sakudo, Akikazu; Onodera, Takashi

    2017-05-23

    In this study, the virucidal effect of a novel electrically charged disinfectant CAC-717 was investigated. CAC-717 is produced by applying an electric field to mineral water containing calcium hydrogen carbonate to generate mesoscopic crystals. Virus titration analysis showed a >3 log reduction of influenza A viruses after treatment with CAC-717 for 1 min in room temperature, while infectivity was undetectable after 15 min treatment. Adding bovine serum albumin to CAC-717 solution did not affect the disinfectant effect. Although CAC-717 is an alkaline solution (pH=12.39), upon contact with human tissue, its pH becomes almost physiological (pH 8.84) after accelerated electric discharge, which enables its use against influenza viruses. Therefore, CAC-717 may be used as a preventative measure against influenza A viruses and for biosecurity in the environment.

  19. Calcium oxalate crystal adherence to hyaluronan-, osteopontin-, and CD44-expressing injured/regenerating tubular epithelial cells in rat kidneys

    NARCIS (Netherlands)

    M. Asselman (Marino); A. Verhulst; M.E. de Broe; C.F. Verkoelen

    2003-01-01

    textabstractRetention of crystals in the kidney is an essential early step in renal stone formation. Studies with renal tubular cells in culture indicate that hyaluronan (HA) and osteopontin (OPN) and their mutual cell surface receptor CD44 play an important role in calcium oxalate

  20. Chronic calcium pyrophosphate crystal inflammatory arthritis induced by extreme hypomagnesemia in short bowel syndrome

    Directory of Open Access Journals (Sweden)

    Hahn Markus

    2012-09-01

    Full Text Available Abstract Background Short bowel syndrome (SBS may induce a plethora of clinical symptoms ranging from underweight to nutrient-, vitamin- and electrolyte deficiencies. The objective of this case report is to illustrate how demanding the management of a 60 year old patient with SBS and recurrent joint attacks was for different medical disciplines. Case presentation The patient with SBS presented with a body mass index of 16.5 kg/m2 after partial jejunoileal resection of the small intestine with a six year long history of recurrent pain attacks in multiple peripheral joints, chronic diarrhoea and food intolerances. Pain attacks occurred 4–5 times a week with a median consumption of 15 mg prednisone per day. The interdisciplinary workup after several gastroenterologic, rheumatologic, radiologic, psychiatric and orthopedic consultations is shown including successful treatment steps. Clinical diagnosis revealed no systemic inflammatory disease, but confirmed extreme hypomagnesemia (0.2 mmol/l after reproducible pathological magnesium resorption tests as causative for chronic calcium pyrophosphate crystal inflammatory arthritis (pseudogout, chondrocalcinosis. Multidisciplinary treatment included application of colchicines, parenteral nutrition and magnesium substitution, antiperistaltic agents and avoidance of intolerant foods. Normalization of magnesium levels and a marked remission of joint attacks were achieved after six months with significant reduction of prednisone to 1.5 mg/day. Conclusion Despite the rarity of this condition, it is important to know that hypomagnesaemia may be associated with calcium pyrophosphate crystal inflammatory arthritis (chondrocalcinosis and that SBS patients may be prone to develop extreme hypomagnesaemia causing recurrent joint attacks without systemic inflammation.

  1. Peptide induced crystallization of calcium carbonate on wrinkle patterned substrate: implications for chitin formation in molluscs.

    Science.gov (United States)

    Ghatak, Anindita Sengupta; Koch, Marcus; Guth, Christina; Weiss, Ingrid M

    2013-06-04

    We here present the nucleation and growth of calcium carbonate under the influence of synthetic peptides on topographically patterned poly(dimethylsiloxane) (PDMS) substrates, which have a controlled density of defects between the wrinkles. Experiments with two lysine-rich peptides derived from the extracellular conserved domain E22 of the mollusc chitin synthase Ar-CS1, AKKKKKAS (AS8) and EEKKKKKES (ES9) on these substrates showed their influence on the calcium carbonate morphology. A transition from polycrystalline composites to single crystalline phases was achieved with the peptide AS8 by changing the pH of the buffer solution. We analyzed three different pH values as previous experiments showed that E22 interacts with aragonite biominerals more strongly at pH 7.75 than at pH 9.0. At any given pH, crystals appeared in characteristic morphologies only on wrinkled substrates, and did not occur on the flat, wrinkle-free PDMS substrate. These results suggest that these wrinkled substrates could be useful for controlling the morphologies of other mineral/peptide and mineral/protein composites. In nature, these templates are formed enzymatically by glycosyltransferases containing pH-sensitive epitopes, similar to the peptides investigated here. Our in vitro test systems may be useful to gain understanding of the formation of distinct 3D morphologies in mollusc shells in response to local pH shifts during the mineralization of organic templates.

  2. Factors affecting crystallization, dispersion, and aggregation of calcium oxalate monohydrate in various urinary environments

    Science.gov (United States)

    Christmas, Kimberly Gail

    The mechanisms for the formation of kidney stones are not well understood. One possible mechanism is the formation of aggregates in the nephron tubules of the kidneys. However, altering the urinary environment may be a method to help prevent the recurrence of the formation of kidney stones. The primary inorganic constituent found in kidney stones of North American patients is calcium oxalate monohydrate (COM). In this research, studies on the effect of mixing rate on COM precipitation showed that rapid mixing compared to slow mixing produced smaller particle sizes and a narrower particle size distribution due to the more uniform supersaturation level. The findings are consistent with the general contention that mixing directly influences nucleation rate while mixing rate has relatively little influence over rate of growth in precipitation processes. Screening and central composite experimental designs are used to determine the effect of various factors on the aggregation and dispersion characteristics of previously grown calcium oxalate monohydrate (COM) crystals in artificial urinary environments of controlled variables. The variables examined are pH, calcium, oxalate, pyrophosphate, citrate, and protein concentrations in ultrapure water and artificial urine. Optical density measurements, zeta potential analysis, particle size analyzer, optical microscopy, AFM force measurements, protein adsorption, and ions and small molecule adsorption have been used to assess the state of aggregation and dispersion of the COM crystals and to elucidate the mechanisms involved in such a complex system. The data indicate that our model protein, mucin, acts as a dispersant. This is attributed to steric hindrance resulting from the adsorbed mucoprotein. Oxalate, however, promotes aggregation. Interesting interactions between protein and oxalate along with protein and citrate are observed. Such interactions (synergistic or antagonistic) are found to depend on the concentrations of

  3. Influence of salt-to-moisture ratio on starter culture and calcium lactate crystal formation.

    Science.gov (United States)

    Agarwal, S; Powers, J R; Swanson, B G; Chen, S; Clark, S

    2008-08-01

    The occurrence of L(+)-lactate crystals in hard cheeses continues to be an expense to the cheese industry. Salt tolerance of the starter culture and the salt-to-moisture ratio (S:M) in cheese dictate the final pH of cheese, which influences calcium lactate crystal (CLC) formation. This research investigates these interactions on the occurrence of CLC. A commercial starter was selected based on its sensitivity to salt, less than and greater than 4.0% S:M. Cheddar cheese was made by using either whole milk (3.25% protein, 3.85% fat) or whole milk supplemented with cream and ultrafiltered milk (4.50% protein, 5.30% fat). Calculated amounts of salt were added at milling (pH 5.40 +/- 0.02) to obtain cheeses with less than 3.6% and greater than 4.5% S:M. Total and soluble calcium, total lactic acid, and pH were measured and the development of CLC was monitored in cheeses. All cheeses were vacuum packaged and gas flushed with nitrogen gas and aged at 7.2 degrees C for 15 wk. Concentration of total lactic acid in high S:M cheeses ranged from 0.73 to 0.80 g/100 g of cheese, whereas that in low S:M cheeses ranged from 1.86 to 1.97 g/100 g of cheese at the end of 15 wk of aging because of the salt sensitivity of the starter culture. Concentrated milk cheeses with low and high S:M exhibited a 30 to 28% increase in total calcium (1,242 and 1,239 mg/100 g of cheese, respectively) compared with whole milk cheeses with low and high S:M (954 and 967 mg/100 g of cheese, respectively) throughout aging. Soluble calcium was 41 to 35% greater in low S:M cheeses (low-salt whole milk cheese and low-salt concentrated milk cheese; 496 and 524 mg/100 g of cheese, respectively) compared with high S:M cheeses (high-salt whole milk cheese and high-salt concentrated milk cheese; 351 and 387 mg/100 g of cheese, respectively). Because of the lower pH of the low S:M cheeses, CLC were observed in low S:M cheeses. However, the greatest intensity of CLC was observed in gas-flushed cheeses made with

  4. Rare-Earth Calcium Oxyborate Piezoelectric Crystals ReCa4O(BO33: Growth and Piezoelectric Characterizations

    Directory of Open Access Journals (Sweden)

    Fapeng Yu

    2014-07-01

    Full Text Available Rare-earth calcium oxyborate crystals, ReCa4O(BO33 (ReCOB, Re = Er, Y, Gd, Sm, Nd, Pr, and La , are potential piezoelectric materials for ultrahigh temperature sensor applications, due to their high electrical resistivity at elevated temperature, high piezoelectric sensitivity and temperature stability. In this paper, different techniques for ReCOB single-crystal growth are introduced, including the Bridgman and Czochralski pulling methods. Crystal orientations and the relationships between the crystallographic and physical axes of the monoclinic ReCOB crystals are discussed. The procedures for dielectric, elastic, electromechanical and piezoelectric property characterization, taking advantage of the impedance method, are presented. In addition, the maximum piezoelectric coefficients for different piezoelectric vibration modes are explored, and the optimized crystal cuts free of piezoelectric cross-talk are obtained by rotation calculations.

  5. Tamm-Horsfall mucoprotein reduces promotion of calcium oxalate crystal aggregation induced by urate in human urine in vitro.

    Science.gov (United States)

    Grover, P K; Marshall, V R; Ryall, R L

    1994-08-01

    1. Increasing the concentration of dissolved urate promotes calcium oxalate crystallization in urine from which Tamm-Horsfall mucoprotein, an inhibitor of calcium oxalate crystal aggregation, has almost completely been removed. This study aimed to determine whether the effect of urate could be reduced or abolished by a physiological concentration of Tamm-Horsfall mucoprotein. This was approached in two ways. 2. The effect of Tamm-Horsfall mucoprotein on calcium oxalate crystallization induced by urate was tested in ultrafiltered (10 kDa) urine samples from 10 healthy men. Tamm-Horsfall mucoprotein (35 mg/l) was added to half of each specimen, the urate concentration was increased by the addition of sodium urate solution and crystallization was induced by a standard load of oxalate. The remainder of each urine specimen was used as a control; these specimens were treated with an identical amount of urate solution, but contained no Tamm-Horsfall mucoprotein. Tamm-Horsfall mucoprotein had no effect on the urinary metastable limit or on the deposition of calcium oxalate, but significantly reduced the size of the particles precipitated. 3. The effect of increasing the urate concentration in the presence of Tamm-Horsfall mucoprotein was tested. Tamm-Horsfall mucoprotein (35 mg/l) was added to 10 ultrafiltered urine samples as before, the samples were divided, and the concentration of urate was increased in half of each specimen. Compared with the control to which no urate was added, urate significantly reduced the amount of oxalate required to induce spontaneous calcium oxalate nucleation and increased the median volume and the particle size of the material deposited.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Characterization of a C4 maize pyruvate orthophosphate dikinase ...

    African Journals Online (AJOL)

    PRECIOUS

    2010-01-11

    Jan 11, 2010 ... affected the phenotypes of plants particularly tillers and enhanced yield of transgenic IR64 rice plants in the greenhouse. Key words: Indica rice IR64, Maize (Zea mays), photosynthesis, PPDK (pyruvate orthophosphate dikinase), C4 rice. INTRODUCTION. In order to meet the demand for food from the ...

  7. Characterization of a C 4 maize pyruvate orthophosphate dikinase ...

    African Journals Online (AJOL)

    Pyruvate orthophosphate dikinase (PPDK) is a key enzyme in plants that utilize the C4 photosynthetic pathway to fix CO2. The enzymatic reaction catalyzed by PPDK is critically controlled by light and is one of the rate-limiting steps of the C4 pathway. The intact maize (Zea mays) C4-PPDK gene, containing its own promoter, ...

  8. Basic calcium phosphate crystals induce monocyte/macrophage IL-1β secretion through the NLRP3 inflammasome in vitro.

    Science.gov (United States)

    Pazár, Borbála; Ea, Hang-Korng; Narayan, Sharmal; Kolly, Laeticia; Bagnoud, Nathalie; Chobaz, Véronique; Roger, Thierry; Lioté, Frédéric; So, Alexander; Busso, Nathalie

    2011-02-15

    Basic calcium phosphate (BCP) crystals are associated with severe osteoarthritis and acute periarticular inflammation. Three main forms of BCP crystals have been identified from pathological tissues: octacalcium phosphate, carbonate-substituted apatite, and hydroxyapatite. We investigated the proinflammatory effects of these BCP crystals in vitro with special regard to the involvement of the NLRP3-inflammasome in THP-1 cells, primary human monocytes and macrophages, and mouse bone marrow-derived macrophages (BMDM). THP-1 cells stimulated with BCP crystals produced IL-1β in a dose-dependent manner. Similarly, primary human cells and BMDM from wild-type mice also produced high concentrations of IL-1β after crystal stimulation. THP-1 cells transfected with short hairpin RNA against the components of the NLRP3 inflammasome and mouse BMDM from mice deficient for NLRP3, apoptosis-associated speck-like protein, or caspase-1 did not produce IL-1β after BCP crystal stimulation. BCP crystals induced macrophage apoptosis/necrosis as demonstrated by MTT and flow cytometric analysis. Collectively, these results demonstrate that BCP crystals induce IL-1β secretion through activating the NLRP3 inflammasome. Furthermore, we speculate that IL-1 blockade could be a novel strategy to inhibit BCP-induced inflammation in human disease.

  9. Growth and Characterization of Lanthanum Calcium Oxoborate LaCa4O(BO3)3 Single Crystals

    Science.gov (United States)

    Takeda, Hiroaki; Sako, Hideki; Shimizu, Hiroyuki; Kodama, Kaoru; Nishida, Masahiro; Nakao, Hiroshi; Nishida, Takashi; Okamura, Soichiro; Shikida, Takashi; Shiosaki, Tadashi

    2003-09-01

    Lanthanum calcium oxoborate LaCa4O(BO3)3 (LaCOB) bulk single crystals were grown by the Czochralski technique. The crystals have almost constant transmittances between 320 and 2500 nm. The relationship between the growth habit and crystallographic abc - rectangular XYZ axes was clarified. Some dielectric and piezoelectric constants as well as elastic compliance constants of the LaCOB crystals were evaluated. The surface acoustic wave (SAW) and pseudo-SAW (PSAW) parameters of the LaCOB crystals were also measured. For the SAW, the largest electromechanical coupling coefficient of approximately 0.26% and a velocity of 3550 m/s were obtained for the YX orientation. For the PSAW, these parameters were approximately 0.6% and 4000 m/s for the ZY orientation.

  10. Correlation between air pollution and crystal pattern of calcium oxalate in plant leaves of street trees in Itami City. [Ginkgo biloba; Salix babylonica; Aphananthe aspera; Robinia pseudoacacia

    Energy Technology Data Exchange (ETDEWEB)

    Umemoto, K.; Tatsumi, S.

    1975-01-01

    A characteristic difference in calcium oxalate crystal patterns in leaves of roadside trees planted in relatively unpolluted northern parts of Itami City and in parts of the city polluted by automobile exhaust was discovered. The species of trees examined were Ginkgo biloba, Salix babylonica, Aphananthe aspera, Robinia pseudoacacia, and Poplar. The leaves of trees grown in relatively less air polluted areas displayed crystal aggregates of calcium oxalate (50-80 micron) that were arranged in rows on both sides of the central vein; some scattered crystal aggregates between veins were observed. Trees grown in air polluted areas showed irregular crystal patterns and more scattering of the crystals between veins. The cause of the observed differences in the pattern of crystal aggregates was attributed to the difference in metabolism of trees under different environmental conditions. Air pollutants disturb the normal metabolism of the tree and cause hyperproduction of calcium oxalate.

  11. Roles of Macrophage Exosomes in Immune Response to Calcium Oxalate Monohydrate Crystals

    Directory of Open Access Journals (Sweden)

    Nilubon Singhto

    2018-02-01

    Full Text Available In kidney stone disease, macrophages secrete various mediators via classical secretory pathway and cause renal interstitial inflammation. However, whether their extracellular vesicles, particularly exosomes, are involved in kidney stone pathogenesis remained unknown. This study investigated alterations in exosomal proteome of U937-derived macrophages (by phorbol-12-myristate-13-acetate activation after exposure to calcium oxalate monohydrate (COM crystals for 16-h using 2-DE-based proteomics approach. Six significantly altered proteins in COM-treated exosomes were successfully identified by nanoscale liquid chromatography–electrospray ionization–electron transfer dissociation tandem mass spectrometry as proteins involved mainly in immune processes, including T-cell activation and homeostasis, Fcγ receptor-mediated phagocytosis, interferon-γ (IFN-γ regulation, and cell migration/movement. The decreased heat shock protein 90-beta (HSP90β and increased vimentin were confirmed by Western blotting. ELISA showed that the COM-treated macrophages produced greater level of interleukin-1β (IL-1β, one of the markers for inflammasome activation. Functional studies demonstrated that COM-treated exosomes enhanced monocyte and T-cell migration, monocyte activation and macrophage phagocytic activity, but on the other hand, reduced T-cell activation. In addition, COM-treated exosomes enhanced production of proinflammatory cytokine IL-8 by monocytes that could be restored to its basal level by small-interfering RNA targeting on vimentin (si-Vimentin. Moreover, si-Vimentin could also abolish effects of COM-treated exosomes on monocyte and T-cell migration as well as macrophage phagocytic activity. These findings provided some implications to the immune response during kidney stone pathogenesis via exosomal pathway of macrophages after exposure to COM crystals.

  12. Correlation between the degree of air pollution and the distribution of calcium oxalate crystals in the gingko leaf

    Energy Technology Data Exchange (ETDEWEB)

    Umemoto, K.; Hozumi, K.

    1972-12-01

    It is now found that the leaves of the gingko tree, Gingko biloba Linn, start to change color prematurely (in July) and are frequently shed considerably in advance of their normal release due to exposure to automotive exhaust. A comparison was made between leaves taken from clean locations free from exhaust fumes and others from high traffic intersections in urban areas. There were noticeable changes in the distribution of inorganic crystals, calcium oxalate, which suggested a biochemical synthesis in the leaf of oxalic acid from inspired carbon monoxide, carbon dioxide, and water, with subsequent neutralization by calcium ion. Results showed significant differences in the size and shape of the crystals, and in their original sites in the leaf. An effect of air pollution from automobile exhaust fumes upon the metabolism of the gingko tree is thus strikingly evident. 4 figures, 2 tables.

  13. Simultaneous EPR and optical spectroscopy of pure and Rh-doped barium calcium titanate crystals

    Science.gov (United States)

    Grachev, Valentin; Malovichko, Galina; Schirmer, Ortwin

    2003-03-01

    The large electro-optic coefficients and high holographic sensitivity of barium calcium titanate (Ba0.77Ca0.23TiO3, BCT) make it promising candidate for various applications, since it has no drawback related to the phase transition at 280 K like barium titanate. The nominally pure and Rh doped BCT crystals were investigated with the help of optical absorption spectroscopy, light induced absorption change measurements and electron paramagnetic resonance (EPR) in the temperature range between 4.2 and 300 K. Analyzing angular dependencies of the EPR lines we succeed to identify low-symmetry and nearly cubic centers of iron trace impurity. Four other paramagnetic defects were found after illumination: Ti3+, Rh2+, O- and Pt3+. All these defects are participants of charge transfer processes. At the light energy E about 1.3 eV the holes abandon Ti4+ creating the paramagnetic electronic Ti3+. At E > 2.3 eV O2- ions capture the holes and create hole O- centers and simultaneously Ti3+ concentration increases. Nearly located non-controlled or intentionally introduced impurities (Sr, K, Na, Ca...) may serve as pins for the fixation of the electrons and holes. Additional correlated changes were found at E > 3.2 eV (band-band transition), when EPR lines of Rh2+, Pt3+ appear and intensities of Ti3+, O- and Fe3+ essentially increase. Models of defects involved in these light induced processes are proposed.

  14. Electronic structure and bonding in calcium apatite crystals: Hydroxyapatite, fluorapatite, chlorapatite, and bromapatite

    Science.gov (United States)

    Rulis, Paul; Ouyang, Lizhi; Ching, W. Y.

    2004-10-01

    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 energy-loss function for each system. Band results indicate that these materials are all wide band-gap insulators in the range of ˜5.3eV . The bonding results show that the systems are dominated by two sets of structures: a PO4 sublattice and Ca channels populated by ion columns of X . The exact positions and orientations of the ions in the Ca channels are subject to debate on many levels. To contribute to the discussion, we analyze the position and orientation of the hydroxyl group from hydroxyapatite along the Ca channel using total-energy comparisons.

  15. Enzyme-accelerated and structure-guided crystallization of calcium carbonate: role of the carbonic anhydrase in the homologous system.

    Science.gov (United States)

    Müller, Werner E G; Schlossmacher, Ute; Schröder, Heinz C; Lieberwirth, Ingo; Glasser, Gunnar; Korzhev, Michael; Neufurth, Meik; Wang, Xiaohong

    2014-01-01

    The calcareous spicules from sponges, e.g. from Sycon raphanus, are composed of almost pure calcium carbonate. In order to elucidate the formation of those structural skeletal elements, the function of the enzyme carbonic anhydrase (CA), isolated from this species, during the in vitro calcium carbonate-based spicule formation, was investigated. It is shown that the recombinant sponge CA substantially accelerates calcium carbonate formation in the in vitro diffusion assay. A stoichiometric calculation revealed that the turnover rate of the sponge CA during the calcification process amounts to 25 CO2s(-1) × molecule CA(-1). During this enzymatically driven process, initially pat-like particles are formed that are subsequently transformed to rhomboid/rhombohedroid crystals with a dimension of ~50 μm. The CA-catalyzed particles are smaller than those which are formed in the absence of the enzyme. The Martens hardness of the particles formed is ~4 GPa, a value which had been determined for other biogenic calcites. This conclusion is corroborated by energy-dispersive X-ray spectroscopy, which revealed that the particles synthesized are composed predominantly of the elements calcium, oxygen and carbon. Surprising was the finding, obtained by light and scanning electron microscopy, that the newly formed calcitic crystals associate with the calcareous spicules from S. raphanus in a highly ordered manner; the calcitic crystals almost perfectly arrange in an array orientation along the two opposing planes of the spicules, leaving the other two plane arrays uncovered. It is concluded that the CA is a key enzyme controlling the calcium carbonate biomineralization process, which directs the newly formed particles to existing calcareous spicular structures. It is expected that with the given tools new bioinspired materials can be fabricated. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Treatment of a highly-concentrated sulphate-rich synthetic wastewater using calcium hydroxide in a fluidised bed crystallizer.

    Science.gov (United States)

    Maharaj, Chiara; Chivavava, Jemitias; Lewis, Alison

    2018-02-01

    This study aimed to investigate factors that affect the conversion of sulphates and magnesium, and the recovery of gypsum and magnesium hydroxide in the neutralization of a sulphate rich stream using calcium hydroxide, in a laboratory scale seeded fluidised bed crystallizer. Particular focus was on reducing the precipitated fines that escaped with the treated water, through the use of seeds, while removing as much sulphate-compounds from the waste stream as possible. The composition of the total sulphate salts was as follows: 80% magnesium sulphate, calcium sulphate remaining at its saturation concentration (1.5 g/L), with the remainder being sodium sulphate based on typical reverse osmosis retentate concentrations ranging from 1.5 - 120 g/L of total sulphate salts. The fluidised bed crystallizer, using silica seeds, was found to be effective at reducing the formation of gypsum and magnesium hydroxide fines by almost half. Feed concentrations of 35 g/L of total salts yielded better sulphate conversions (±75%), compared to a feed concentration of 8 g/L (±30%). It was possible to remove 99% of the magnesium in the saline wastewater stream using a calcium to sulphate ratio of 1:1 for feed concentrations of 15 g/L and higher. Excess calcium hydroxide suspension improved sulphate conversions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Production of calcium oxalate crystals by the basidiomycete Moniliophthora perniciosa, the causal agent of witches' broom disease of Cacao.

    Science.gov (United States)

    Rio, Maria Carolina S do; de Oliveira, Bruno V; de Tomazella, Daniela P T; Silva, José A Fracassi da; Pereira, Gonçalo A G

    2008-04-01

    Oxalic acid has been shown as a virulence factor for some phytopathogenic fungi, removing calcium from pectin and favoring plant cell wall degradation. Recently, it was published that calcium oxalate accumulates in infected cacao tissues during the progression of Witches' Broom disease (WBD). In the present work we report that the hemibiotrophic basidiomycete Moniliophthora perniciosa, the causal agent of WBD, produces calcium oxalate crystals. These crystals were initially observed by polarized light microscopy of hyphae growing on a glass slide, apparently being secreted from the cells. The analysis was refined by Scanning electron microscopy and the compositon of the crystals was confirmed by energy-dispersive x-ray spectrometry. The production of oxalate by M. perniciosa was reinforced by the identification of a putative gene coding for oxaloacetate acetylhydrolase, which catalyzes the hydrolysis of oxaloacetate to oxalate and acetate. This gene was shown to be expressed in the biotrophic-like mycelia, which in planta occupy the intercellular middle-lamella space, a region filled with pectin. Taken together, our results suggest that oxalate production by M. perniciosa may play a role in the WBD pathogenesis mechanism.

  18. Inhibition of calcium carbonate crystal growth by organic additives using the constant composition method in conditions of recirculating cooling circuits

    Science.gov (United States)

    Chhim, Norinda; Kharbachi, Chams; Neveux, Thibaut; Bouteleux, Céline; Teychené, Sébastien; Biscans, Béatrice

    2017-08-01

    The cooling circuits used in power plants are subject to mineral crystallization which can cause scaling on the surfaces of equipment and construction materials reducing their heat exchange efficiency. Precipitated calcium carbonate is the predominant mineral scale commonly observed in cooling systems. Supersaturation is the key parameter controlling the nucleation and growth of calcite in these systems. The present work focuses on the precipitation of calcite using the constant composition method at constant supersaturation, through controlled addition of reactants to a semi-batch crystallizer, in order to maintain constant solution pH. The determination of the thermodynamic driving force (supersaturation) was based on the relevant chemical equilibria, total alkalinity and calculation of the activity coefficients. Calcite crystallization rates were derived from the experiments performed at supersaturation levels similar to those found in industrial station cooling circuits. Several types of seeds particles were added into the aqueous solution to mimic natural river water conditions in terms of suspended particulate matters content, typically: calcite, silica or illite particles. The effect of citric and copolycarboxylic additive inhibitors added to the aqueous solution was studied. The calcium carbonate growth rate was reduced by 38.6% in the presence of the citric additive and a reduction of 92.7% was observed when the copolycarboxylic additive was used under identical experimental conditions. These results are explained by the location of the adsorbed inhibitor at the crystal surface and by the degree of chemical bonding to the surface.

  19. Crystallization and preliminary crystallographic analysis of calcium-binding protein-2 from Entamoeba histolytica and its complexes with strontium and the IQ1 motif of myosin V

    Energy Technology Data Exchange (ETDEWEB)

    Gourinath, S., E-mail: sgourinath@mail.jnu.ac.in; Padhan, Narendra; Alam, Neelima; Bhattacharya, Alok [School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2005-04-01

    Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. Calcium plays a pivotal role in the pathogenesis of amoebiasis, a major disease caused by Entamoeba histolytica. Two domains with four canonical EF-hand-containing calcium-binding proteins (CaBPs) have been identified from E. histolytica. Even though they have very high sequence similarity, these bind to different target proteins in a Ca{sup 2+}-dependent manner, leading to different functional pathways. Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 111.74, b = 68.83, c = 113.25 Å, β = 116.7°. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 69.18, b = 112.03, c = 93.42 Å, β = 92.8°. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. This complex was crystallized with MPD and ethanol as precipitating agents. These crystals belong to space group P2{sub 1}, with unit-cell parameters a = 60.5, b = 69.86, c = 86.5 Å, β = 97.9°.

  20. The cytospin technique improves the detection of calcium pyrophosphate crystals in synovial fluid samples with a low leukocyte count.

    Science.gov (United States)

    Robier, Christoph; Quehenberger, Franz; Neubauer, Manfred; Stettin, Mariana; Rainer, Franz

    2014-06-01

    In synovial fluids (SF) with low leukocyte or/and crystal counts, important features may be missed, if exclusively smears are examined by polarized microscopy. That may be overcome by cytocentrifuges, which use low-speed centrifugal force to concentrate cells onto a glass slide and thus enhance the number of cells per high power field (HPF). We compared the calcium pyrophosphate (CPP) crystal counts in cytospin preparations with those in common smears of SF. The number of CPP crystals was counted in 50 SF samples by polarized microscopy, and statistical comparisons of the mean values of the cytospin and smear preparations were performed using the Wilcoxon test. The reproducibility within the slides of the cytocentrifuge and smear samples was determined by Spearman's rank correlation. The crystal counts were significantly higher in the cytospin than in the smear preparations (median 96/10 HPF vs. 2.5/10 HPF, p < 0.0001). The correlation in the crystal count between the slides 1 and 2 was significantly higher within the cytocentrifuge than in the smear group (0.97 vs. 0.73, p = 0.0004). CPP-negative cytospin preparations in initially smear-positive slides were not observed. We confirmed that the cytospin technique significantly enhances the number of examinable crystals per HPF, compared to common smears.

  1. Adsorption of phosphonates on gypsum crystals

    NARCIS (Netherlands)

    Weijnen, M.P.C.; Van Rosmalen, G.M.

    1986-01-01

    The absorption of phosphonate inhibitors at the crystal surface of gypsum has been determined from the decrease in phosphonate concentration of the bulk solution. The phosphonate was therefore oxidized to orthophosphate and spectrophotometrically determined as a molybdovanadophosphoric acid complex.

  2. Variation of crystal structure of hydroxyapatite in calcium phosphate cement by the substitution of strontium ions.

    Science.gov (United States)

    Wang, Xiupeng; Ye, Jiandong

    2008-03-01

    New routes were used to introduce strontium into calcium phosphate cement in the present article. The study showed that by mixing 50 wt% amorphous calcium phosphate + amorphous strontium phosphate and 50 wt% dicalcium phosphate dihydrate, hydroxyapatite and Sr-hydroxyapatite precipitated separately in the hydrated cement; whereas, by mixing 50 wt% Sr- amorphous calcium phosphate and 50 wt% dicalcium phosphate dihydrate, strontium can be doped into hydroxyapatite lattice and increase the lattice dimensions and lattice volume. The strontium substituted calcium phosphate cement has potential for use in orthopedic surgeries.

  3. Intrinsically disordered and pliable Starmaker-like protein from medaka (Oryzias latipes) controls the formation of calcium carbonate crystals.

    Science.gov (United States)

    Różycka, Mirosława; Wojtas, Magdalena; Jakób, Michał; Stigloher, Christian; Grzeszkowiak, Mikołaj; Mazur, Maciej; Ożyhar, 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.

  4. CALCIUM PYROPHOSPHATE DIHYDRATE CRYSTAL DEPOSITION DISEASE - A REVIEW OF THE LITERATURE AND A LIGHT AND ELECTRON-MICROSCOPIC STUDY OF A CASE OF THE TEMPOROMANDIBULAR-JOINT WITH NUMEROUS INTRACELLULAR CRYSTALS IN THE CHONDROCYTES

    NARCIS (Netherlands)

    DIJKGRAAF, LC; LIEM, RSB; DEBONT, LGM; BOERING, G

    The pathogenesis of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease of synovial joints is still unclear, although overproduction of extracellular pyrophosphate (PPi) is thought to play a key role. We studied the light and electron microscopic appearances of a case of CPPD crystal

  5. Hemocytes participate in calcium carbonate crystal formation, transportation and shell regeneration in the pearl oyster Pinctada fucata.

    Science.gov (United States)

    Li, Shiguo; Liu, Yangjia; Liu, Chuang; Huang, Jingliang; Zheng, Guilan; Xie, Liping; Zhang, Rongqing

    2016-04-01

    In this study, light microscope, scanning and transmission electron microscope, hematoxylin-eosin and fluorescent staining, and mass spectrometry methods were employed to observe the calcium carbonate (CaCO3) crystal formation, hemocyte release and transportation, and hemocyte distribution at the shell regeneration area and to analyse the proteome of hemocytes in the pearl oyster, Pinctada fucata. The results indicated that intracellular CaCO3 crystals were observed in circulating hemocytes in P. fucata, implying that there was a suitable microenvironment for crystal formation in the hemocytes. This conclusion was further supported by the proteome analysis, in which various biomineralization-related proteins were detected. The crystal-bearing hemocytes, mainly granulocytes, may be released to extrapallial fluid (EPF) by the secretory cavities distributed on the outer surface of the mantle centre. These granulocytes in the EPF and between the regenerated shells were abundant and free. In the regenerated prismatic layer, the granulocytes were fused into each column and fragmented with the duration of shell maturation, suggesting the direct involvement of hemocytes in shell regeneration. Overall, this study provided evidence that hemocytes participated in CaCO3 crystal formation, transportation and shell regeneration in the pearl oyster. These results are helpful to further understand the exact mechanism of hemocyte-mediated biomineralization in shelled molluscs. Copyright © 2016 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2015-04-01

    The deposition of sparingly soluble salts (scaling) within porous media is a major problem encountered in many industrial and environmental applications. In the oil industry scaling causes severe operational malfunctions and, therefore, increasing the total operating and maintenance cost [1]. The most common types of sparingly soluble salts located in oil fields include carbonate and sulfate salts of calcium, strondium and barium[1,2]. Multiple phase flow and tubing surface properties are some of the factors affecting scale formation [3]. The main purpose of the present work was the investigation of the precipitation mechanisms of calcium carbonate (CaCO3) through in situ mixing of two soluble salt solutions in a flow granular medium, in the presence of water miscible organic fluid (ethylene glycol) or non-miscible organic fluid (n-dodecane). All series of experiments were carried out in a two dimensional porous medium made of Plexiglas. For all solutions used in the experiments, the contact angles with the surface of the porous medium and the interfacial tensions were measured. During the experiments, the calcium carbonate crystal growth was continuously monitored and recorded through an optical microscope equipped with a digital programmed video camera. The snap-shots were taken within specific time intervals and their detailed procession gave information concerning the crystal growth rate and kinetics. The pH of the effluent was measured and fluids samples were collected for calcium analysis using Atomic Absorption Spectroscopy (AAS). In all experiments effluent calcium concentration decreased as a function of time, suggesting that CaCO3 precipitation took place inside the porous medium. Crystals of the precipitated salt were identified using Infrared Spectroscopy (IR) and the morphology of the crystals was examined using Scanning Electron Microscopy (SEM). The induction time for precipitation of CaCO3 crystals in the presence of n-dodecane was significantly

  7. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  8. Synthesis, Crystal Structure, and Luminescence Properties of a New Calcium(II Coordination Polymer Based on L-Malic Acid

    Directory of Open Access Journals (Sweden)

    Duraisamy Senthil Raja

    2013-01-01

    Full Text Available A new calcium coordination polymer [Ca(HL-MA]n (H3L-MA = L-malic acid has been solvothermally synthesized. The structure of the newly synthesized complex has been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, reflectance UV-Vis & IR spectra, powder X-ray diffraction (PXRD, and thermogravimetric analysis (TGA. The single crystal structure analysis showed that the complex forms three-dimensional framework. The new Ca(II complex has displayed very high thermal stability which was inferred from TGA and PXRD results. As far as the optical property of the new complex is concerned, the complex emitted its own characteristic sensitized luminescence.

  9. Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu3+-Doped Mixed Rare Earth Nano-Orthophosphates

    Directory of Open Access Journals (Sweden)

    Yan Bing

    2010-01-01

    Full Text Available Abstract Eu3+-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For LaxY1–xPO4: Eu3+, the ion radius distinction between the La3+ and Y3+ is so large that only La0.9Y0.1PO4: Eu3+ shows the pure monoclinic phase. For LaxGd1–xPO4: Eu3+ system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, YxGd1–xPO4: Eu3+, Y0.1Gd0.9PO4: Eu3+ and Y0.5Gd0.5PO4: Eu3+ samples present the pure hexagonal phase and nanorods microstructure, while Y0.9Gd0.1PO4: Eu3+ exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu3+ in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure.

  10. In situ enzymatic removal of orthophosphate by the nucleoside phosphorylase catalyzed phosphorolysis of nicotinamide riboside.

    Science.gov (United States)

    Shriver, J W; Sykes, B D

    1982-09-01

    An enzymatic orthophosphate removal system is described which can be effectively used to continuously remove orthophosphate from biochemical samples. The phosphorolysis of nicotinamide riboside is catalyzed by calf spleen nucleoside phosphorylase to give ribose-1-PO4 and nicotinamide along with a proton. At pH 8 the production of ribose-1-PO4 from orthophosphate is essentially quantitative. This reaction can be monitored optically or by 31P nuclear magnetic resonance (NMR). Equations are given for determining the time required to remove a given amount of phosphate from a typical NMR sample with a known amount of nucleoside phosphorylase. The effects of a competing orthophosphate-producing reaction are considered.

  11. Synthesis of positively charged calcium hydroxyapatite nano-crystals and their adsorption behavior of proteins.

    Science.gov (United States)

    Kandori, Kazuhiko; Oda, Shohei; Fukusumi, Masao; Morisada, Yoshiaki

    2009-10-01

    Positively charged Hap nano-crystals were prepared by using beta-alanine and clarified the adsorption affinity of these surface amide functionalized Hap nano-crystals to proteins. Colloidal surface amide functionalized Hap nano-crystals were prepared by wet method in the presence of various amounts of beta-alanine by changing molar ratio of beta-alanine/Ca (beta/Ca ratio) in the solution. The rod-like nano-crystals were lengthened with addition of beta-alanine though their width did not vary; carboxyl groups of beta-alanine are strongly coordinated to Ca2+ ions exposed on ac and/or bc faces to inhibit particle growth to a- and/or b-axis directions and enhance the particle growth along to the c-axis. No difference can be recognized on the crystal structure among the synthesized Hap nano-crystals by XRD measurements. However, the large difference was recognized by TG-DTA and FTIR measurements. Those measurements revealed that beta-alanine is incorporated on the Hap nano-crystal surface up to the beta/Ca ratio of 1.0, though they are absent in the nano-crystals synthesized at beta/Ca ratio > or = 2.0. The zeta potential (zp) of beta-alanine-Hap nano-crystals prepared at beta/Ca = 0.4 and 1.0 of those incorporating beta-alanine exhibited positive charge at pH crystals were increased 2.3-2.4-fold by their electrostatic attraction force between positively charged beta-alanine-Hap nano-crystals and negatively charged BSA molecules. We were able to control the adsorption affinity of Hap nano-crystal by changing their surface charge.

  12. STUDY OF CRYSTALLIZATION OF CALCIUM SULFATE DIHYDRATE THAT HAS POLYMER ADDITIVES

    Directory of Open Access Journals (Sweden)

    Ustinova Yuliya Valer'evna

    2012-10-01

    A. It is identified that additives based on polymers of different origin affect processes of crystallization, the size and shape of crystals. B. The X-ray diffraction analysis has proven that molecules of polymer additives do not penetrate into the gypsum structure and the chemical composition of the product does not change. C. Methods of thermal analysis have proven that the introduction of polymer additives does not produce any adverse impact on the stability of gypsum crystals, if exposed to temperature fluctuations. D. The major impact produced onto crystallization is the one of the super plasticizer based on the sulfonated melamine-formaldehyde resin.

  13. CCDC 1420580: Experimental Crystal Structure Determination : catena-[(mu-4,4'-sulfonyldibenzoato)-calcium acetylene

    KAUST Repository

    Plonka, Anna M.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  14. CCDC 1420581: Experimental Crystal Structure Determination : catena-[(mu-4,4'-sulfonyldibenzoato)-calcium ethylene

    KAUST Repository

    Plonka, Anna M.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  15. CCDC 1420582: Experimental Crystal Structure Determination : catena-[(mu-4,4'-sulfonyldibenzoato)-calcium ethane

    KAUST Repository

    Plonka, Anna M.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  16. The crystal structures of the psychrophilic subtilisin S41 and the mesophilic subtilisin Sph reveal the same calcium-loaded state.

    Science.gov (United States)

    Almog, Orna; González, Ana; Godin, Noa; de Leeuw, Marina; Mekel, Marlene J; Klein, Daniela; Braun, Sergei; Shoham, Gil; Walter, Richard L

    2009-02-01

    We determine and compare the crystal structure of two proteases belonging to the subtilisin superfamily: S41, a cold-adapted serine protease produced by Antarctic bacilli, at 1.4 A resolution and Sph, a mesophilic serine protease produced by Bacillus sphaericus, at 0.8 A resolution. The purpose of this comparison was to find out whether multiple calcium ion binding is a molecular factor responsible for the adaptation of S41 to extreme low temperatures. We find that these two subtilisins have the same subtilisin fold with a root mean square between the two structures of 0.54 A. The final models for S41 and Sph include a calcium-loaded state of five ions bound to each of these two subtilisin molecules. None of these calcium-binding sites correlate with the high affinity known binding site (site A) found for other subtilisins. Structural analysis of the five calcium-binding sites found in these two crystal structures indicate that three of the binding sites have two side chains of an acidic residue coordinating the calcium ion, whereas the other two binding sites have either a main-chain carbonyl, or only one acidic residue side chain coordinating the calcium ion. Thus, we conclude that three of the sites are of high affinity toward calcium ions, whereas the other two are of low affinity. Because Sph is a mesophilic subtilisin and S41 is a psychrophilic subtilisin, but both crystal structures were found to bind five calcium ions, we suggest that multiple calcium ion binding is not responsible for the adaptation of S41 to low temperatures. Copyright 2008 Wiley-Liss, Inc.

  17. Microvillar injury in renal tubular epithelial cells induced by calcium oxalate crystal and the protective role of epigallocatechin-3-gallate.

    Science.gov (United States)

    Fong-Ngern, Kedsarin; Vinaiphat, Arada; Thongboonkerd, Visith

    2017-01-01

    Pathogenic mechanisms of kidney stone disease remained unclear. This study investigated its initial cellular/molecular mechanisms when calcium oxalate monohydrate (COM) crystal adhered to renal tubular cells. Transmission electron microscopy revealed decreased length and density of microvilli, whereas Western blot analysis showed that whole-cell ezrin (a microvillus-stabilizing protein), not β-actin, was decreased in COM-treated cells. Immunofluorescence staining, followed by laser-scanning confocal microscopy and subcellular fractionations, revealed decreases in both ezrin and F-/β-actin at apical membrane. Cytoskeletal extraction by Triton X-100 showed reduced cytoskeleton-associated ezrin, consistent with colocalization data of ezrin/F-actin. Thr(567)-phosphorylated ezrin and RhoA increased in COM-treated cells. A protein oxidation blot assay showed an increase in oxidized proteins in COM-treated cells that could be prevented by epigallocatechin-3-gallate (EGCG), which also preserved the whole-cell ezrin level, stabilized apical membrane ezrin/F-actin colocalization, and maintained microvillar structure in COM-treated and H2O2-treated cells. Our data clearly demonstrated the reduction of ezrin and actin expression at the apical membrane of COM-treated cells, most likely because of oxidative stress, which could be prevented by EGCG. These findings provide a novel approach to better understanding of the pathogenesis of kidney stone disease in its initial phase and offer potential preventive strategy against microvillar injury induced by COM crystals in patients with kidney stones.-Fong-ngern, K., Vinaiphat, A., Thongboonkerd, V. Microvillar injury in renal tubular epithelial cells induced by calcium oxalate crystal and the protective role of epigallocatechin-3-gallate. © FASEB.

  18. Light-induced charge-transport properties of photorefractive barium-calcium-titanate crystals doped with iron

    Science.gov (United States)

    Veenhuis, H.; Börger, T.; Buse, K.; Kuper, C.; Hesse, H.; Krätzig, E.

    2000-07-01

    Nominally pure and iron doped, as-grown, and thermally annealed photorefractive barium-calcium-titanate crystals of the congruently melting composition Ba0.23Ca0.77TiO3 (BCT) are investigated by holographic and conventional electrical techniques. Refractive-index changes, two-beam-coupling gains, photoconductivities, dark conductivities, and bulk-photovoltaic current densities are measured. As-grown and oxidized crystals are hole conductive and at usual illumination conditions (light wavelength 514.5 nm, light intensity between 0.1 and 1 W/cm2) all measured properties are excellently described by an one-center charge-transport model. The effective electrooptic coefficient r333 is only about 30 pm/V and thus much smaller than the value obtained from interferometric measurements. Two-beam-coupling gains as high as 7 cm-1 are achieved. Doping with iron increases considerably the effective trap density, and bulk-photovoltaic fields of the order of some kilovolts per centimeter are observed in iron-doped crystals. Typical response times of iron-doped, as-grown, or oxidized crystals are about 0.5 s at 1 W/cm2. Reduction yields electron-conductive BCT. The dark storage time increases from 6 min in the as-grown state to 3 h upon a slight reduction treatment, but decreases for strongly reduced samples. The investigation reveals that BCT will become a very promising alternative to barium-titanate crystals (BaTiO3) for many applications.

  19. Crystal arthritides - gout and calcium pyrophosphate arthritis : Part 2: clinical features, diagnosis and differential diagnostics.

    Science.gov (United States)

    Schlee, S; Bollheimer, L C; Bertsch, T; Sieber, C C; Härle, P

    2017-02-23

    Gout develops in four stages beginning with an asymptomatic increase in blood levels of uric acid. An acute gout attack is an expression of an underlying inflammatory process, which in the course of time is self-limiting. Without therapy monosodium urate crystals remain in the synovial fluid and synovial membrane and trigger more acute attacks. In the course of the disease monosodium urate crystals form deposits (tophi) leading in severe forms to irreversible joint deformities with loss of functionality. In 20% of cases gout leads to involvement of the kidneys. Overproduction of uric acid can cause nephrolithiasis. These stones can be composed of uric acid or calcium phosphate. Another form of kidney disease caused by gout is uric acid nephropathy. This is a form of abacterial chronic inflammatory response with deposition of sodium urate crystals in the medullary interstitium. Acute obstructive nephropathy is relatively rare and characterized by renal failure due to uric acid precipitation in the tubules because of rapid cell lysis that occurs, for example, with chemotherapy. There is a causal interdependence between the occurrence of hyperuricemia and hypertension. Uric acid activates the renin-angiotensin-aldosterone (RAA) system and inhibits nitric oxide (NO) with the possible consequence of a rise in systemic vascular resistance or arteriolar vasculopathy; however, uric acid is also an apparently independent risk factor for atherosclerosis. In contrast to young patients, the diagnosis of an acute gout attack in the elderly can be a challenge for the physician. Polyarticular manifestations and obscure symptoms can make it difficult to differentiate it from rheumatoid arthritis and calcium pyrophosphate deposition disease (CPPD). Aspiration of synovial fluid with visualization of urate crystals using compensated polarized light microscopy is the gold standard for diagnosis of acute gout. Moreover, analysis of synovial fluid enables a distinction from septic

  20. Calcium Sulfoaluminate Sodalite (Ca 4 Al 6 O 12 SO 4 ) Crystal Structure Evaluation and Bulk Modulus Determination

    KAUST Repository

    Hargis, Craig W.

    2013-12-12

    The predominant phase of calcium sulfoaluminate cement, Ca 4(Al6O12)SO4, was investigated using high-pressure synchrotron X-ray diffraction from ambient pressure to 4.75 GPa. A critical review of the crystal structure of Ca4(Al 6O12)SO4 is presented. Rietveld refinements showed the orthorhombic crystal structure to best match the observed peak intensities and positions for pure Ca4(Al6O 12)SO4. The compressibility of Ca4(Al 6O12)SO4 was studied using cubic, orthorhombic, and tetragonal crystal structures due to the lack of consensus on the actual space group, and all three models provided similar results of 69(6) GPa. With its divalent cage ions, the bulk modulus of Ca4(Al6O 12)SO4 is higher than other sodalites with monovalent cage ions, such as Na8(AlSiO4)6Cl2 or Na8(AlSiO4)6(OH)2·H 2O. Likewise, comparing this study to previous ones shows the lattice compressibility of aluminate sodalites decreases with increasing size of the caged ions. Ca4(Al6O12)SO4 is more compressible than other cement clinker phases such as tricalcium aluminate and less compressible than hydrated cement phases such as ettringite and hemicarboaluminate. © 2013 The American Ceramic Society.

  1. Crystal growth mechanism of calcium phosphate coatings on titanium by electrochemical deposition

    NARCIS (Netherlands)

    Mokabber, Taraneh; Lu, Liqiang; van Rijn, Patrick; Vakis, Antonis I.; Pei, Yutao T.

    2018-01-01

    The pulsed current electrochemical deposition of calcium phosphate (Ca-P) coatings on a titanium substrate was investigated in this study. The effects of applied voltage and H2O2 concentration in the electrolyte solution on the phase composition and coating morphology were studied using X-ray

  2. The effect of intracrystalline and surface-bound osteopontin on the attachment of calcium oxalate dihydrate crystals to Mandin-Darby canine kidney (MDCK) cells in ultrafiltered human urine

    DEFF Research Database (Denmark)

    Thurgood, Lauren A.; Sørensen, Esben Skipper; Ryall, Rosemary L.

    2012-01-01

    Osteopontin has been shown to both promote and inhibit the attachment of calcium oxalate monohydrate crystals to cultured renal epithelial cells in aqueous media. In this study we examined the role of OPN on the growth and attachment of calcium oxalate dihydrate crystals, to which it more readily...

  3. Inhibition of calcium oxalate crystal deposition on kidneys of urolithiatic rats by Hibiscus sabdariffa L. extract.

    Science.gov (United States)

    Laikangbam, Reena; Damayanti Devi, M

    2012-06-01

    The present study aims at systematic evaluation of the calyces of Hibiscus sabdariffa to establish its scientific validity for anti-urolithiatic property using ethylene glycol-induced hyperoxaluria model in male albino rats. Administration of a mixture of 0.75% ethylene glycol and 2% ammonium chloride resulted in hyperoxaluria as well as increased renal excretion of calcium and phosphate. The decrease in the serum calcium concentration indicates an increased calcium oxalate formation. Supplementation of aqueous extract of H. sabdariffa at different doses (250, 500 and 750 mg/kg body weight) significantly lowered the deposition of stone-forming constituents in the kidneys and serum of urolithiatic rats. These findings have been confirmed through histological investigations. Results of in vivo genotoxicity testing showed no significant chromosomal aberrations in the bone marrow cells of ethylene glycol-induced rats. The plant extracts at the doses investigated induced neither toxic nor lethal effects and are safe. It can be concluded that the calyces of H. sabdariffa are endowed with anti-urolithiatic activity and do not have genotoxic effects. Thus, it can be introduced in clinical practices and medicine in the form of orally administered syrup after further investigations and clinical trials.

  4. Crystallization of calcium carbonate with the filtration of aqueous solutions through a microporous membrane

    Science.gov (United States)

    Ananeva, E. A.; Mesyats, E. A.; Sergievskii, V. V.

    2017-11-01

    It is established that the filtration of water through a microporous membrane does not change the hardness of the water; it does, however, reduce the amount of scale deposit, due to the crystallization of salts in water in the form of aragonite. The effect is consistently observed in water with a hardness of more than 7.0 H, a content of hydrocarbonate ions of more than 500 mg/L, and a pH ≥ 7.3. It is shown that introducing the seeds of calcite crystals into a filtrate results in the precipitation of calcite rather than aragonite. It is concluded that quasi-softening in the case of hard water microfiltration is caused by the removal of calcite micronuclei, and thus by conditions being created for the crystallization of aragonite as a thermodynamically less stable form.

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

    Energy Technology Data Exchange (ETDEWEB)

    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); 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); Yazdani-Pedram, Mehrdad [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

  6. Infusum Daun Alpukat Sebagai Inhibitor Kristalisasi Kalsium Oksalat pada Ginjal (THE AVOCADO LEAVES INFUSUM AS INHIBITOR ON RENAL CALCIUM OXALATE CRYSTALIZATION

    Directory of Open Access Journals (Sweden)

    Rini Madyastuti

    2016-01-01

    Full Text Available Urine crystal is a crystal nucleus which tend to form urine stone. The case of urine stone seems to beincreased every year. Crystallization could induce acute tubular necrosis which impact on renal dysfunction.The signs of this condition are high level of urea, creatinine and decrease glomerulus filtration rate. Theobjective of this research was to evaluate the effects of infusum Persea americana Mill as an inhibitorcrystallization which induced by ethylene glycol on white male rats. 20 male rats were divided into 4groups; K1 as negative group received only distilled water ad libitum, K2 as positive group receiveddistilled water containing ethylene glycol, K3 (dose 5% and K4 (dose 10% as treatment groups receivedwater containing ethylene glycol and avocado leaves infusion. Phytochemsitry screening of infusion avocadoleaves consisted of flavonoid, saponin, tanine and quinone. Result of analysis showed that the level ofureum and creatinine on K2 was higher than K3 and K4 group. The increased level could be inhibited byinfusion avocado leaves. The measurement of glomerular filtration rate in treatment groups wassignificantly different (p<0.05. Descriptive histopathology observation showed that renal lesio in grouptreatment (K3 and K4 were declined. Large crystal calcium oxalate on K2 group was observed by usingpolarized microscope, whereas small crystal calcium oxalate were seen in the infusion of avocado leavesgroups. These result showed the ability of infusion of avocado leaves as an inhibitor on the growth ofcrystallization calcium oxalate

  7. Preparation of Cerium Orthophosphate Nanosphere by Coprecipitation Route and Its Structural, Thermal, Optical, and Electrical Characterization

    Directory of Open Access Journals (Sweden)

    Seema Verma

    2014-01-01

    Full Text Available Cerium orthophosphate (CePO4 nanoparticles were synthesized via wet chemical coprecipitation technique using cerium nitrate hexahydrate for Ce3+ ion and ammonium dihydrogen phosphate for PO43- ion source. X-ray diffraction (XRD analysis suggests that the material belongs to monoclinic crystal system with crystallite size of 49.3 nm. Scanning electron microscope (SEM and transmission electron microscope (TEM reveal the surface morphology of the prepared nanoparticles as nanospheres having grain size in the range of 30–50 nm. The energy dispersive X-ray analysis (EDAX gives elemental composition present in the grown nanomaterial. Thermogravimetric analysis suggests that the structural phase transition is above 800°C. The optical properties include UV-VIS-NIR absorption and the photoluminescence spectrum shows the absorption and emission peaks in the ultraviolet region. The dielectric constant (ε/  and ac conductivity properties were investigated with regard to change in temperature (40 to 500°C and frequency (5 kHz to 1 MHz. The dielectric measurement indicates that the transition is diffused and the activation energy values decrease suggesting that the conduction mechanism is due to hopping of the charge carriers from one site to another.

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

    Directory of Open Access Journals (Sweden)

    G. A. Silva-Castro

    2015-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  10. Investigation of early growth of calcium hydroxide crystals in cement solution by soft x-ray transmission microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Harutyunyan, V. S.; Kirchheim, A. P.; Monteiro, P. J. M.; Aivazyan, A. P.; Fischer, P.

    2009-02-02

    Research on cement hydration was performed at the full-field soft transmission X-ray microscope XM-1 located at beamline 6.1.2 at the Advanced Light Source (ALS) in Berkeley CA which is operated by the Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California. A series of works [1-3] has been conducted using this microscope for the in situ observation and qualitative analysis of through-solution hydration products and products of topochemical reactions, which form in cementitious aqueous solutions. This paper studies the precipitation of the calcium hydroxide (CH) crystals from the cement solution. The analysis of successive images of the hydration process provides critical quantitative information about the growth rate of calcium hydroxide (CH) crystals, the supersaturation ratio, and the kinetic and diffusion coefficients of the growth process. ASTM Type II portland cement and 6% C{sub 4}A{sub 3}{bar S} admixture were mixed in aqueous solution and saturated with respect to CH and gypsum. The C{sub 4}A{sub 3}{bar S} admixture was included in the experimental program because of the general research program on expansive cements, and adding C{sub 4}A{sub 3}{bar S} to portland cement is an efficient method of generating ettringite and significant early-age expansion. The solution/solid materials ratio was 10 cm{sup 3}/g, which is higher than the one existing in regular concrete and mortars; to compensate for this dilution, the solution was originally saturated with CH and gypsum. To allow sufficient transmission of the soft X-rays, a small droplet was taken from the supernatant solution and assembled in the sample holder, and then squeezed between two silicon nitride windows for the analysis. The X-ray optical setup of the microscope XM-1 is described elsewhere [2]. In this experiment, a wavelength of 2.4 nm (516.6 eV) was used. The radiation transmitting the sample was detected using an X-ray CCD camera, with a resolution of 35 nm provided

  11. Suggestive Evidence for the Involvement of the Second Calcium and Surface Loop in Interfacial Binding: Monoclinci and Trigonal Crystal Structures of a Quadruple Mutant of Phospholipase A2

    Energy Technology Data Exchange (ETDEWEB)

    Sekar,K.; Yogavel, M.; Kanaujia, S.; Sharma, A.; Velmurugan, D.; Poi, M.; Dauter, Z.; Tsai, M.

    2006-01-01

    The crystal structures of the monoclinic and trigonal forms of the quadruple mutant K53,56,120,121M of recombinant bovine pancreatic phospholipase A{sub 2} (PLA{sub 2}) have been solved and refined at 1.9 and 1.1 Angstroms resolution, respectively. Interestingly, the monoclinic form reveals the presence of the second calcium ion. Furthermore, the surface-loop residues are ordered and the conformation of residues 62-66 is similar to that observed in other structures containing the second calcium ion. On the other hand, in the trigonal form the surface loop is disordered and the second calcium is absent. Docking studies suggest that the second calcium and residues Lys62 and Asp66 from the surface loop could be involved in the interaction with the polar head group of the membrane phospholipid. It is hypothesized that the two structures of the quadruple mutant, monoclinic and trigonal, represent the conformations of PLA2 at the lipid interface and in solution, respectively. A docked structure with a phospholipid molecule and with a transition-state analogue bound, one at the active site coordinating to the catalytic calcium and the other at the second calcium site, but both at the i-face, is presented.

  12. Calcium carbonate crystallizations on hypogean mural paintings: a pilot study of monitoring and diagnostics in Roman catacombs

    Science.gov (United States)

    Tapete, D.; Fratini, F.; Mazzei, B.; Camaiti, M.; Cantisani, E.; Riminesi, C.; Manganelli Del Fà, R.; Cuzman, O.; Tiano, P.

    2012-04-01

    One of the deterioration processes affecting mural paintings and rock surfaces within manmade hypogea consists in the formation of calcium carbonate crystallizations, which can create thick coverage and incrustations, even in some cases speleothems. These chemical reactions necessarily require the availability of calcium sources, which can be also of anthropogenic origin (e.g., lime-based mortars). Microclimate parameters also represent environmental forcing factors, on which the morphology and the degree of crystallinity of the precipitated carbonates depend. Understanding past/recent dynamics of carbonate precipitation implies a deep knowledge of the relationships between the exposed surfaces and the microclimate conditions, the impacts of external factors (e.g., groundwater infiltration and percolation from the overlying soil) and how they change over time. This is particularly fundamental for the preservation of hypogean sites which have not comparison with other typologies of environment due to their uniqueness, such as the ancient catacombs carved underneath the suburbs of Rome (Italy), since the 2nd century AD. In this paper we present the multidisciplinary methodological approach designed for the instrumental monitoring of the microphysical environment of the Catacombs of Saints Mark, Marcellian and Damasus, in the framework of the co-operation between the Institute for the Conservation and Valorization of Cultural Heritage and Pontifical Commission for Sacred Archaeology, Vatican, on the project HYPOGEA. Temperature inside the catacomb and on the surfaces, air relative humidity and CO2 concentration are the main of the parameters continuously measured by means of data loggers installed within the cubicles. Contemporarily, standardized methods of photographic documentation and digital micro-photogrammetry are used for change detection analysis of the painted surfaces and ancient plasters, as well as of the test areas purposely realized by applying fresh

  13. Linking crystal structure with temperature-sensitive vibrational modes in calcium carbonate minerals.

    Science.gov (United States)

    Xu, Ben; Poduska, Kristin M

    2014-09-07

    We demonstrate a correlation between how an IR-active vibrational mode responds to temperature changes and how it responds to crystallinity differences. Infrared (IR) spectroscopy was used to track changes in carbonate-related vibrational modes in three different CaCO3 polymorphs (calcite, aragonite, and vaterite) and CaMg(CO3)2 (dolomite) during heating. Of the three characteristic IR-active carbonate modes, the in-plane bending mode (ν4) shows the most pronounced changes with heating in polymorphs that have planar carbonate arrangements (calcite, aragonite, and dolomite). In contrast, this mode is virtually unchanged in vaterite, which has a canted arrangement of carbonate units. We correlate these trends with recent studies that identified the ν4 mode as most susceptible to changes related to crystallinity differences in calcite and amorphous calcium carbonate. Thus, our results suggest that studies of packing arrangements could provide a generalizable approach to identify the most diagnostic vibrational modes for tracking either temperature-dependent or crystallinity-related effects in IR-active solids.

  14. Laser- and gamma-ray induced crystallization of IR-transmitting calcium gallate glass

    Science.gov (United States)

    Nishida, T.; Kubuki, S.; Takashima, Y.; Mikami, M.; Yagi, T.

    1994-12-01

    Ar+-laser ( λ=488 nm) irradiation of calcium gallate (CG) glass with the composition of 60CaO·39Ga2O3·Fe2O3 resulted in a distinct decrease in the IR transmittance ( T) due to the formation of crystalline CaGa2O4 and CaGa4O9 phases. The Mössbauer spectrum of non-irradiated glass comprised a broad doublet due to distorted Fe3+(Td) with δ, Δ, and Γ of 0.20, 1.33, and 1.00 mm s-1, respectively. An additional doublet due to Fe3+(Td) was observed in the Ar+-irradiated glass and δ, Δ, and Γ were 0.17, 1.32, and 0.75 mm s-1, respectively. A decrease in T was also observed after the60Co γ-ray irradiation with doses ≥105Gy, and the precipitation of CaO, Ga2O3, and CaGa4O7 phases was confirmed by X-ray diffraction.

  15. Citrate effects on amorphous calcium carbonate (ACC) structure, stability, and crystallization

    DEFF Research Database (Denmark)

    Tobler, Dominique Jeanette; Rodriguez Blanco, Juan Diego; Dideriksen, Knud

    2015-01-01

    -mineral interactions, both in nature and for industrial processes. In this study, ACC formation and its crystallization are monitored in real time as a function of citrate (CIT) concentration in solution. Additionally, synchrotron radiation pair distribution function analyses combined with solid-state, spectroscopic......, and microscopic techniques are used to determine the effect of CIT on ACC structure, composition, and size. Results show an increase in ACC lifetime coupled with an increase in CIT uptake by ACC and slight changes in ACC atomic structure with an increase in CIT concentration. ACC does not form at concentrations...... of vaterite formation suggest that these solution complexes form a calcite-type atomic arrangement while CIT probably also acts as a growth inhibitor....

  16. A biomimetic strategy to form calcium phosphate crystals on type I collagen substrate

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhang [Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, 5 Lower Kent Ridge Road 119074, Singapore (Singapore); Neoh, Koon Gee [Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge 119260, Singapore (Singapore); Kishen, Anil, E-mail: anil.kishen@utoronto.ca [Discipline of Endodontics, Faculty of Dentistry, University of Toronto, 124 Edward Street, Toronto, ON (Canada)

    2010-07-20

    Objective: The aim of this study is to induce mineralization of collagen by introducing phosphate groups onto type I collagen from eggshell membrane (ESM) by treating with sodium trimetaphosphate (STMP). This strategy is based on the hypothesis that phosphate groups introduced on collagen can mimic the nucleating role of phosphorylated non-collagenous proteins bound to collagen for inducing mineralization in natural hard tissue. Method: The collagen membrane was phosphorylated by treating it with a solution of STMP and saturated calcium hydroxide. The phosphorylated collagen was subsequently exposed to a mineralization solution and the pattern of mineralization on the surface of phosphorylated collagen substrate was analyzed. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), field emission electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and microhardness test were used to characterize the collagen substrate and the pattern of minerals formed on the collagen surface. Results: The FTIR and EDX results indicated that the phosphate groups were incorporated onto the collagen surface by treatment with STMP. During the mineralization process, the plate-like mineral, octacalcium phosphate (OCP), which was initially formed on the surface of ESM, was later transformed into needle-like hydroxyapatite (HAP) as indicated by the SEM, FESEM, EDX and XRD findings. The microhardness test displayed significant increase in the Knoop hardness number of the mineralized collagen. Conclusions: Phosphate groups can be introduced onto type I collagen surface by treating it with STMP and such phosphorylated collagen can induce the mineralization of type I collagen.

  17. Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    1999-10-04

    A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the, radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.

  18. The effect of crystal structure of TiO2 nanotubes on the formation of calcium phosphate coatings during biomimetic deposition

    Science.gov (United States)

    Liu, Yi; Kim, Sun; McLeod, John A.; Li, Jun; Guo, Xiaoxuan; Sham, Tsun-Kong; Liu, Lijia

    2017-02-01

    The crystallization process of bioactive calcium phosphate (CaP) species via biomimetic deposition onto anodic TiO2 nanotubes is investigated. The porous surface of nanostructured TiO2 provides an ideal substrate for CaP crystallization. The compositions of CaP coatings are studied using X-ray absorption near-edge structures (XANES) at the Ca K-edge. Using detection modes with different probing depths, both the surface of the CaP coating and the CaP-TiO2 interface are simultaneously analyzed. Calcium phosphate (CaP) species, such as hydroxyapatite (HAp), octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O, OCP), brushite (CaHPO4·2H2O, DCPD), and amorphous calcium phosphate (ACP), are found in the CaP coatings. TiO2 nanotubes of amorphous and anatase phases are comparatively studied to determine their effect on the efficiency of CaP formation and the phase transformation among CaP species in prolonged deposition time. It is found the composition of CaP coating has a strong dependency on the crystal structure of TiO2 substrate and the kinetics (deposition time).

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

    Science.gov (United States)

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

    2016-01-01

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

  20. Ammonia-nitrogen and orthophosphate removal by immobilized ...

    African Journals Online (AJOL)

    Chlorella sp. isolated from municipal wastewater and entrapped in calcium alginate as algal sheets was employed to remove inorganic nutrients from domestic secondary effluents in parallel-plate bioreactor after starvation. The key factors affecting the nutrient removal efficiency, system stability and reuse efficiency of ...

  1. Effects of Tamm-Horsfall protein with normal and reduced sialic acid content upon the crystallization of calcium phosphate and calcium oxalate in human urine

    National Research Council Canada - National Science Library

    Hallson, P C; Choong, S K; Kasidas, G P; Samuell, C T

    1997-01-01

    To examine the effects of Tamm-Horsfall protein (THP) of normal and low sialic acid content on urinary crystallization, and establish whether there are changes conducive to the formation of kidney stones...

  2. Separate effects of urinary chondroitin sulphate and heparan sulphate on the crystallization of urinary calcium oxalate: differences between stone formers and normal control subjects.

    Science.gov (United States)

    Shum, D K; Gohel, M D

    1993-07-01

    1. Urinary glycosaminoglycans were recovered from the papain digest of polyanions precipitated sequentially by cetylpyridinium chloride and sodium acetate-saturated ethanol. Those from the early morning urine of 48 stone formers and 43 normal control subjects measured 11 and 16 micrograms of uronic acid/ml of urine, respectively. 2. Preparative agarose gel electrophoresis of the recovered glycosaminoglycans in barium acetate buffer (pH 5.8) yielded fractions containing purely chondroitin sulphate, co-polymeric chondroitin/dermatan sulphates and heparan sulphate. Identification was based on the susceptibility of the fractions to chondroitinase or nitrous acid treatment. Similar compositions of glycosaminoglycan classes were observed in samples from stone formers and normal control subjects. 3. The fractionated glycosaminoglycans were dissolved in urine ultrafiltrate to assay for nucleation-promoting and growth-inhibiting activities towards crystallization of urinary calcium oxalate. When compared at the same uronic acid concentration, both the urinary chondroitin sulphate isomers and heparan sulphates of stone formers demonstrated the capacity to enhance crystal nucleation from calcium oxalate endogenous in urine ultrafiltrates, whereas only urinary heparan sulphates of normal control subjects demonstrated this capacity. 4. Tissue-derived reference chondroitin sulphate, dermatan sulphate and heparin, when similarly tested, showed negligible crystal nucleation-promoting activity. The tissue-derived heparan sulphate was similar to the urinary heparan sulphates in showing marked crystal nucleation-promoting activity. 5. Crystal-growth inhibitory activity was evident in all urinary glycosaminoglycan fractions studied. In particular, urinary heparan sulphate of normal control subjects showed higher activity than that of stone formers or the chondroitin sulphate isomers of both stone formers and normal control subjects (P < 0.005).

  3. Response of microbial growth to orthophosphate and organic carbon influx in copper and plastic based plumbing water systems.

    Science.gov (United States)

    Park, Se-Keun; Kim, Yeong-Kwan; Choi, Sung-Chan

    2008-07-01

    Consequences of orthophosphate addition for corrosion control in water distribution pipes with respect to microbial growth were investigated using batch and dynamic tests. Batch tests showed that the release of copper in either low or high organic carbon content water was decreased by 69% and 56% with addition 206 microg PO(4)-P, respectively. Dosing of orthophosphate against corrosion did not increase microbial growth potential in the water and in the biofilm in both corroded and uncorroded systems receiving tap water with a low content of organic carbon and of biodegradable organic fraction. However, in tap water having a high concentration of organic carbon from acetate addition, orthophosphate addition promoted the growth of bacteria, allowed more bacteria to assemble on corroded and uncorroded surfaces, and increased the consumption of organic carbon. Orthophosphate consumption did not exceed 1% of the amount of easily biodegradable organic carbon required for microbial growth, and the orthophosphate demand for corrosion control greatly exceeded the nutritional requirement of microbial growth. The results of the dynamic tests demonstrated that there was a significant effect of interaction between biodegradable organic carbon and orthophosphate on biofilm growth, whereby the effect of orthophosphate flux on microbial growth was dependent on the levels of biodegradable organic carbon. Controlling an easily biodegradable organic carbon would be therefore necessary to minimize the microbial growth potential induced by orthophosphate-based anticorrosion treatment.

  4. Apo And Calcium-Bound Crystal Structures of Alpha-11 Giardin, An Unusual Annexin From 'Giardia Lamblia'

    Energy Technology Data Exchange (ETDEWEB)

    Pathuri, P.; Nguyen, E.T.; Svard, S.G.; Luecke, H.; /UC, Irvine /Uppsala U. /Karolinska Inst.

    2007-07-12

    Alpha-11 giardin is a member of the multi-gene alpha-giardin family in the intestinal protozoan, Giardia lamblia. This gene family shares an ancestry with the annexin super family, whose common characteristic is calcium-dependent binding to membranes that contain acidic phospholipids. Several alpha giardins are highly expressed during parasite-induced diarrhea in humans. Despite being a member of a large family of proteins, little is known about the function and cellular localization of alpha-11 giardin, although giardins are often associated with the cytoskeleton. It has been shown that Giardia exhibits high levels of alpha-11 giardin mRNA transcript throughout its life cycle; however, constitutive over-expression of this protein is lethal to the parasite. Determining the three-dimensional structure of an alpha-giardin is essential to identifying functional domains shared in the alpha-giardin family. Here we report the crystal structures of the apo and Ca{sup 2+}-bound forms of alpha-11 giardin, the first alpha giardin to be characterized structurally. Crystals of apo and Ca{sup 2+}-bound alpha-11 giardin diffracted to 1.1 angstroms and 2.93 angstroms, respectively. The crystal structure of selenium-substituted apo alpha-11 giardin reveals a planar array of four tandem repeats of predominantly {alpha}-helical domains, reminiscent of previously determined annexin structures, making this the highest-resolution structure of an annexin to date. The apo alpha-11 giardin structure also reveals a hydrophobic core formed between repeats I/IV and II/III, a region typically hydrophilic in other annexins. Surprisingly, the Ca{sup 2+}-bound structure contains only a single calcium ion, located in the DE loop of repeat I and coordinated differently from the two types of calcium sites observed in previous annexin structures. The apo and Ca{sup 2+}-bound alpha-11 giardin structures assume overall similar conformations; however, Ca2+-bound alpha-11 giardin crystallized in a lower

  5. Irritant contact dermatitis caused by needle-like calcium oxalate crystals, raphides, in Agave tequilana among workers in tequila distilleries and agave plantations.

    Science.gov (United States)

    Salinas, M L; Ogura, T; Soffchi, L

    2001-02-01

    It was found that needle-like calcium oxalate crystals, raphides, are found abundantly in all tissues of Agave tequilana plants; thus, 1 droplet (0.03 ml) of juice pressed from leaves contains 100-150 crystals, 30-500 microm in length, sharpened at both ends. In tequila distilleries, 5/6 of the workers who handle the agave stems have experienced the characteristic irritation. In contrast, only 1/3 of workers in agave plantations who harvest agave plants, complain of the irritation. It is confirmed that all the irritation suffered in both distilleries and plantations takes place at bodily locations where the plants come into contact with the worker's skin in the course of their work.

  6. Calcium hydroxyapatite crystal deposition with intraosseous penetration involving the posterior aspect of the cervical spine: a previously unreported cause of neck pain.

    Science.gov (United States)

    Urrutia, Julio; Contreras, Oscar

    2017-05-01

    Calcific tendinitis is a frequent disorder caused by hydroxyapatite crystal deposition; however, bone erosions from calcific tendinitis are unusual. The spinal manifestation of this disease is calcific tendinitis of the longus colli muscle; this disease has never been described in the posterior aspect of the spine. We report a case of calcium hydroxyapatite crystal deposition involving the posterior cervical spine eroding the bone cortex. A 57-year-old woman presented with a 5-month history of left-sided neck pain. Radiographs showed C4-C5 interspinous calcification with lytic compromise of the posterior arch of C4. Magnetic resonance imaging confirmed a lytic lesion of the posterior arch of C4, with a soft tissue mass extending to the C4-C5 interspinous space; calcifications were observed as very low signal intensity areas on T1 and T2 sequences, surrounded by gadolinium-enhanced soft tissues. A computed tomography (CT) scan confirmed the bone erosions and the soft tissue calcifications. A CT-guided needle biopsy was performed; it showed vascularized connective tissue with inflammatory histiocytic infiltration and multinucleated giant cells; Alizarin Red stain confirmed the presence of hydroxyapatite crystals. The patient was treated with anti-inflammatories for 2 weeks. She has been asymptomatic in a 6-month follow-up; a CT scan at the last follow-up revealed reparative remodeling of bone erosions. This is the first report of calcium hydroxyapatite crystal deposition with intraosseous penetration involving the posterior aspect of the cervical spine. Considering that this unusual lesion can be misinterpreted as a tumor or infection, high suspicion is required to avoid unnecessary surgical procedures.

  7. Formation of 32P-labelled Polyphosphates in Reactor-irradiated Solutions of Orthophosphate

    DEFF Research Database (Denmark)

    Fenger, Jørgen Folkvard; Pagsberg, Palle Bjørn

    1973-01-01

    Aqueous solutions of potassium orthophosphate were reactor irradiated and analysed by electrophoresis. The resulting distributions of 32P-activity in phosphorus oxyanions resemble the ones obtained with reactor-irradiated solid phosphates. Even in dilute solutions, polymers are formed; their tota...

  8. New orthophosphates matrices of the NZP-like structure for immobilization of actinides

    Energy Technology Data Exchange (ETDEWEB)

    Tomilin, S.V.; Lukinykh, A.N.; Lizin, A.A.; Spirykov, V.I. [FSUE SSC RF ' ' Research Institute of Atomic Reactors' ' , Dimitrovgrad (Russian Federation); Orlova, A.I. [Nizhny Novgorod State Univ. (Russian Federation)

    2004-07-01

    This work presents the results of synthesis and X-ray diffraction analysis of new actinides orthophosphates A{sup I}M{sub 2}{sup IV}(PO{sub 4}){sub 3} where A{sup I} = Li, Na, K, Rb; and M{sup IV} = U, Np and Pu. The compounds were obtained by the high-temperature synthesis. (orig.)

  9. Evaluation of Material Constants and Temperature Properties in Lanthanum Calcium Oxoborate LaCa4O(BO3)3 Single Crystals

    Science.gov (United States)

    Shimizu, Hiroyuki; Kodama, Kaoru; Takeda, Hiroaki; Nishida, Takashi; Shikida, Takashi; Okamura, Soichiro; Shiosaki, Tadashi

    2004-09-01

    Lanthanum calcium oxoborate LaCa4O(BO3)3 (LaCOB) single crystals were successfully grown by the Czochralski technique. It was found that LaCOB crystals belong to the monoclinic system (point group m) and the total number of independent material constants that should be determined is 27. Twenty-four of the 27 material constants at room temperature were determined by the resonance-antiresonance method. The normalized first-order temperature coefficients of some constants e.g., {\\varepsilon11}T, {\\varepsilon22}T, {\\varepsilon33}T and {\\varepsilon13}T determined at 10 kHz were 56.30, -273.6, 135.8 and -258.4 and d11 and d12 were -408.3 and 83.60 ppm/°C, respectively. Additionally, the thermal expansion coefficients e.g., α11, α22 and α33 determined on a single crystal cut along the X, Y and Z rectangular directions by the thermodilatometry measurement were 7.36× 10-6, 8.17× 10-6 and 11.4× 10-6/°C, respectively. As a result of the evaluation, most of the material constants and temperature properties necessary for investigating the properties of piezoelectric devices typified by SAW were obtained.

  10. Extraction and estimation of the quantity of calcium oxalate crystals in the foliage of conifer and hardwood trees

    Science.gov (United States)

    Rakesh Minocha; Bradley Chamberlain; Stephanie Long; Swathi A. Turlapati; Gloria. Quigley

    2015-01-01

    The main goal of this study was to develop a method for the extraction and indirect estimation of the quantity of calcium oxalate (CaOx) in the foliage of trees. Foliar tissue was collected from a single tree of each species (five conifers and five hardwoods) for comparison of extractions in different solvents using 10 replicates per species from the same pool of...

  11. Orthophosphate removal from aqueous solutions using drinking-water treatment sludge.

    Science.gov (United States)

    Piaskowski, Krzysztof

    2013-01-01

    Drinking-water treatment sludge (DWTS) is a by-product generated during the production of drinking water where iron hydroxides are the main component of the sludge. The aim of the study presented here was to determine the effectiveness of using ferric sludge from two underground water treatment stations to remove orthophosphates from a model solution. The analyses were performed in static conditions. The sludge was dosed in a dry and suspended form. Using sludge dried at room temperature and preparing the suspension again proved to be much less effective in orthophosphate removal than using a suspension brought directly from the station. An increase in process effectiveness with a decreasing pH was observed for all the analysed sludge. Due to the low cost and high capability, DWTS has the potential to be utilised for cost-effective removal of phosphate from wastewater.

  12. The use of an ultrafiltration technique for measurement of orthophosphate in shallow wetlands.

    Science.gov (United States)

    Zhang, A; Oldham, C

    2001-02-05

    The overestimation of orthophosphate by filterable reactive phosphorus (FRP) measurement techniques has long been accepted. The aim of this study was to quantify that overestimation in 17 wetlands over time. Specifically an ultrafiltration technique was used prior to the application of the molybdenum blue phosphorus detection method to quantify orthophosphate concentrations. Samples were collected over a 6-month period and analysed for total filterable (PO4). FRP correlated well with PO4, however, FRP overestimated PO4 particularly with increasing colloidal phosphorus concentration. The ratio of DOC to TFP (C:P) influenced the fate of PO4 in the water, implying that DOC was forming complexes with phosphorus. The PO4 concentrations decreased with increasing C:P ratios in some of the wetlands over the 6-month monitoring period.

  13. The Effect of Orthophosphate as a Copper Corrosion Inhibitor in High Alkalinity Drinking Water Systems

    Science.gov (United States)

    2007-03-01

    drinking water’s aesthetics (taste, appearance), reduce discoloration in fixtures, and maintain the strength of the plumbing system. Suppliers have...Studies have shown that on average, daily copper intake is 3200 μg. Copper comes from foods such as shellfish, meat , eggs, vegetables, nuts...stagnation. In five out of six cases, the addition of orthophosphate led to a statistically significant reduction in copper levels (at a 95 percent

  14. Impact of orthophosphate addition on biofilm development in drinking water distribution systems.

    Science.gov (United States)

    Gouider, Mbarka; Bouzid, Jalel; Sayadi, Sami; Montiel, Antoine

    2009-08-15

    The contamination of the water distribution network results from fixed bacteria multiplication (biofilm) on the water pipe walls, followed by their detachment and their transport in the circulating liquid. The presence of biofilms in distribution networks can result in numerous unwanted problems for the user such as microbial contamination of the distributed water and deterioration of the network (bio-corrosion). For old networks, lead-containing plumbings can be a serious cause of worry for the consumer owing to the release of lead ions in the circulating water. Among the solutions considered to reduce the presence of lead in drinking water, the addition of orthophosphates constitutes an interesting alternative. However, the added orthophosphate may cause--even at low doses--additional microbial growth. The main objective of this study was to evaluate the impact of the orthophosphate treatment on the biofilm development in the water supplied by the Joinville-le-Pont water treatment plant (Eau de Paris, France). For this purpose, a laboratory pilot plant was devised and connected to the considered water network. Two quantification methods for monitoring the biofilm formation were used: the enumeration on R2A agar and the determination of proteins. For the biofilm detachment operation, an optimization of the rinsing step was firstly conducted in order to distinguish between free and fixed biomass. The data obtained showed that there was a linear relation between both quantification methods. They also showed that, for the tested water, the bacterial densities were not affected by orthophosphate addition at a treatment rate of 1mg PO(4)(3-)/L.

  15. Ozone-Induced Responses in Croton floribundus Spreng. (Euphorbiaceae): Metabolic Cross-Talk between Volatile Organic Compounds and Calcium Oxalate Crystal Formation

    Science.gov (United States)

    Cardoso-Gustavson, Poliana; Bolsoni, Vanessa Palermo; de Oliveira, Debora Pinheiro; Guaratini, Maria Tereza Gromboni; Aidar, Marcos Pereira Marinho; Marabesi, Mauro Alexandre; Alves, Edenise Segala; de Souza, Silvia Ribeiro

    2014-01-01

    Here, we proposed that volatile organic compounds (VOC), specifically methyl salicylate (MeSA), mediate the formation of calcium oxalate crystals (COC) in the defence against ozone (O3) oxidative damage. We performed experiments using Croton floribundus, a pioneer tree species that is tolerant to O3 and widely distributed in the Brazilian forest. This species constitutively produces COC. We exposed plants to a controlled fumigation experiment and assessed biochemical, physiological, and morphological parameters. O3 induced a significant increase in the concentrations of constitutive oxygenated compounds, MeSA and terpenoids as well as in COC number. Our analysis supported the hypothesis that ozone-induced VOC (mainly MeSA) regulate ROS formation in a way that promotes the opening of calcium channels and the subsequent formation of COC in a fast and stable manner to stop the consequences of the reactive oxygen species in the tissue, indeed immobilising the excess calcium (caused by acute exposition to O3) that can be dangerous to the plant. To test this hypothesis, we performed an independent experiment spraying MeSA over C. floribundus plants and observed an increase in the number of COC, indicating that this compound has a potential to directly induce their formation. Thus, the tolerance of C. floribundus to O3 oxidative stress could be a consequence of a higher capacity for the production of VOC and COC rather than the modulation of antioxidant balance. We also present some insights into constitutive morphological features that may be related to the tolerance that this species exhibits to O3. PMID:25165889

  16. Stabilizing function for myristoyl group revealed by the crystal structure of a neuronal calcium sensor, guanylate cyclase-activating protein 1.

    Science.gov (United States)

    Stephen, Ricardo; Bereta, Grzegorz; Golczak, Marcin; Palczewski, Krzysztof; Sousa, Marcelo Carlos

    2007-11-01

    Guanylate cyclase-activating proteins (GCAPs) are Ca(2+)-binding proteins myristoylated at the N terminus that regulate guanylate cyclases in photoreceptor cells and belong to the family of neuronal calcium sensors (NCS). Many NCS proteins display a recoverin-like "calcium-myristoyl switch" whereby the myristoyl group, buried inside the protein in the Ca(2+)-free state, becomes fully exposed upon Ca(2+) binding. Here we present a 2.0 A resolution crystal structure of myristoylated GCAP1 with Ca(2+) bound. The acyl group is buried inside Ca(2+)-bound GCAP1. This is in sharp contrast to Ca(2+)-bound recoverin, where the myristoyl group is solvent exposed. Furthermore, we provide direct evidence that the acyl group in GCAP1 remains buried in the Ca(2+)-free state and does not undergo switching. A pronounced kink in the C-terminal helix and the presence of the myristoyl group allow clustering of sequence elements crucial for GCAP1 activity.

  17. On the induction of homogeneous bulk crystallization in Eu-doped calcium aluminosilicate glass by applying simultaneous high pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Muniz, R. F., E-mail: robsonfmuniz@yahoo.com.br [Institut Lumière Matière, UMR 5306 CNRS-Université Lyon 1, Université de Lyon, 69622 Villeurbanne (France); Departamento de Física, Universidade Estadual de Maringá, 87020900, Maringá, PR (Brazil); Ligny, D. de [Department of Materials Science, Glass and Ceramics, University of Erlangen Nürnberg, Martensstr. 5, 91058 Erlangen (Germany); Le Floch, S.; Martinet, C.; Guyot, Y. [Institut Lumière Matière, UMR 5306 CNRS-Université Lyon 1, Université de Lyon, 69622 Villeurbanne (France); Rohling, J. H.; Medina, A. N.; Sandrini, M.; Baesso, M. L. [Departamento de Física, Universidade Estadual de Maringá, 87020900, Maringá, PR (Brazil); Andrade, L. H. C.; Lima, S. M. [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul, C.P. 351, Dourados, MS (Brazil)

    2016-06-28

    From initial calcium aluminosilicate glass, transparent glass-ceramics have been successfully synthesized under simultaneous high pressure and temperature (SHPT). Possible homogeneous volumetric crystallization of this glassy system, which was not achieved previously by means of conventional heat treatment, has been put in evidence with a SHPT procedure. Structural, mechanical, and optical properties of glass and glass-ceramic obtained were investigated. Raman spectroscopy and X-ray diffraction allowed to identify two main crystalline phases: merwinite [Ca{sub 3}Mg(SiO{sub 4}){sub 2}] and diopside [CaMgSi{sub 2}O{sub 6}]. A Raman scanning profile showed that the formation of merwinite is quite homogeneous over the bulk sample. However, the sample surface also contains significant diopside crystals. Instrumented Berkovich nanoindentation was applied to determine the effect of SHPT on hardness from glass to glass-ceramic. For Eu-doped samples, the broadband emission due to 4f{sup 6}5d{sup 1} → 4f{sup 7} transition of Eu{sup 2+} was studied in both host systems. Additionally, the {sup 5}D{sub 0} → {sup 7}F{sub J} transition of Eu{sup 3+} was used as an environment probe in the pristine glass and the glass-ceramic.

  18. Response surface methodology based extraction of Tribulus terrestris leads to an upsurge of antilithiatic potential by inhibition of calcium oxalate crystallization processes.

    Directory of Open Access Journals (Sweden)

    Jyoti Kaushik

    Full Text Available Tribulus terrestris has significant antilithiatic efficacy established via both in vitro as well as in vivo studies and is used in numerous anti-urolithiatic herbal formulations viz. Cystone, Uriflow, Uritone and Neeri. However, to fully utilize its antilithiatic potential, the influence of different extraction parameters on antilithiatic ability of T. terrestris aqueous extract needs elucidation. Thus, the current study was undertaken using statistically optimized extraction conditions for aqueous extract preparation. Response surface methodology was employed to observe the influence of three variables i.e. temperature (°C, time (h and solid: liquid ratio (S: L on the extraction yield (% and protein content (mg/g of T. terrestris aqueous extract. RSM results revealed that the high S:L ratio, low temperature and reduced incubation time were optimal conditions for aqueous extraction. Under such extraction conditions the protein content reached the value of 26.6±1.22 mg/g and the obtained extraction yield was 27.32±1.62%. The assessment of antilithiatic activity of 4 selected extracts (AE1-4, revealed enhanced nucleation and aggregation inhibition of calcium oxalate crystals with AE1 and AE2, which in addition significantly altered the size and morphology of calcium oxalate monohydrate (COM crystals compared to AE3 and AE4. In vitro cell culture based studies on renal epithelial cells (MDCK, NRK-52E and PK 15 proved that the AE1 showed higher cytoprotective potency by increasing cell viability as compared to the oxalate treated group. The free radical scavenging activity of aqueous extract lowered the reactive oxygen specie's induced damage and potentially reduced the signals of programmed cell death due to oxalate injury. In addition, modulation of the COM crystal morphology was enhanced by AE1 as compared to AE2. The FTIR and GC-MS analysis of AE1, showed the presence of biomolecules which could aid in the attenuation of lithiatic process. In

  19. A comparison of amorphous calcium carbonate crystallization in aqueous solutions of MgCl2 and MgSO4: implications for paleo-ocean chemistry

    Science.gov (United States)

    Han, Mei; Zhao, Yanyang; Zhao, Hui; Han, Zuozhen; Yan, Huaxiao; Sun, Bin; Meng, Ruirui; Zhuang, Dingxiang; Li, Dan; Liu, Binwei

    2017-07-01

    Based on the terminology of "aragonite seas" and "calcite seas", whether different Mg sources could affect the mineralogy of carbonate sediments at the same Mg/Ca ratio was explored, which was expected to provide a qualitative assessment of the chemistry of the paleo-ocean. In this work, amorphous calcium carbonate (ACC) was prepared by direct precipitation in anhydrous ethanol and used as a precursor to study crystallization processes in MgSO4 and MgCl2 solutions having different concentrations at 60 °C (reaction times 240 and 2880 min). Based on the morphology of the aragonite crystals, as well as mineral saturation indices and kinetic analysis of geochemical processes, it was found that these crystals formed with a spherulitic texture in 4 steps. First, ACC crystallized into columnar Mg calcite by nearly oriented attachment. Second, the Mg calcite changed from columnar shapes into smooth dumbbell forms. Third, the Mg calcite transformed into rough dumbbell or cauliflower-shaped aragonite forms by local dissolution and precipitation. Finally, the aragonite transformed further into spherulitic radial and irregular aggregate forms. The increase in Ca2+ in the MgSO4 solutions compared with the MgCl2 solutions indicates the fast dissolution and slow precipitation of ACC in the former solutions. The phase transition was more complete in the 0.005 M MgCl2 solution, whereas Mg calcite crystallized from the 0.005 M MgSO4 solution, indicating that Mg calcite could be formed more easily in an MgSO4 solution. Based on these findings, aragonite and Mg calcite relative to ACC could be used to provide a qualitative assessment of the chemistry of the paleo-ocean. Therefore, calcite seas relative to high-Mg calcite could reflect a low concentration MgSO4 paleo-ocean, while aragonite seas could be related to an MgCl2 or high concentration of MgSO4 paleo-ocean.

  20. The Crystal Structures of the Calcium Aluminogallates CaAlGaO 4 and Ca 2AlGaO 5

    Science.gov (United States)

    Kahlenberg, V.; Shaw, C. S. J.

    2001-02-01

    The crystal structures of two calcium aluminogallates have been investigated by single-crystal X-ray diffraction methods. Ca2AlGaO5 is a quenched high-pressure phase prepared at 1250°C and 2.5 GPa. The compound belongs to the brownmillerite structure type (space group I2mb, a=5.2823(6) Å, b=14.613(2) Å, c=5.4739(8) Å, V=422.5(9) Å3, Z=4, Dcalc=4.04 g cm-3, wR2=0.072 for 586 reflections with I>2σ(I)). Main building units are (1) layers of perovskite-type corner-connected MeO6-octahedra perpendicular to [010] and (2) zweier single chains of MeO4-tetrahedra running parallel to [100] (Me=Al, Ga). The stacking of the layers and sheets of single chains results in a three-dimensional network with Ca ions in the interstitial voids. Single crystals of CaAlGaO4 (space group P121/c1, a=7.9817(1) Å, b=8.7415(1) Å, c= 10.4430(2) Å, β=94.84(2)°, V=726.0(3) Å 3, Z=8, Dcalc=3.67 g cm-3, wR2=0.079 for 971 reflections with I>2σ(I)) were synthesized at ambient pressure and a temperature of 1500°C. The structure consists of layers of S6R of MeO4-tetrahedra perpendicular to [100]. The stacking of the layers parallel to the a-axis results in a framework with channels occupied by the Ca cations. The sequence of up (U) and down (D) pointing apices of adjacent tetrahedra within a single ring is UUDUDD. CaAlGaO4 is isotypic with the monoclinic modification of CaGa2O4.

  1. Comparison of Physicochemical Properties of Nano- and Microsized Crystals in the Urine of Calcium Oxalate Stone Patients and Control Subjects

    Directory of Open Access Journals (Sweden)

    Jie Gao

    2014-01-01

    Full Text Available Purpose. To compare the properties of different sizes of urinary crystallites between calcium oxalate (CaOx calculi patients and healthy controls. Methods. We studied the average particle size, size distribution, intensity-autocorrelation curve, zeta potential (ζ, conductivity, mobility, aggregation state, and stability of different sizes of urinary crystallites by nanoparticle size analysis and transmission electron microscopy after filtration through a microporous membrane with an aperture size from 0.22 μm to 0.45, 1.2, 3, and 10 μm. Results. The urinary crystallites of the CaOx calculi patients were uneven and much easy to aggregate than those of controls. The number of large-sized crystallites of the patients was significantly more than that of the controls. The main components of the nanosized urinary crystallites in patients were CaOx monohydrate (COM, uric acid, and β-calcium phosphate, and these components were basically similar to those of the microsized urinary crystallites. The urinary crystallites of the calculi patients were easier to aggregate than that of the controls, and the small-sized urinary crystallites were much easier to agglomerate. Conclusions. The urinary system of CaOx calculi patients is unstable and highly susceptible to urinary crystallite aggregation. The rapid aggregation of urinary crystallites may be the key factor affecting urolithiasis formation.

  2. Crystal structure of pira toxin-I: a calcium-independent, myotoxic phospholipase A{sub 2} - homologue from Bothrops pirajai venom

    Energy Technology Data Exchange (ETDEWEB)

    Canduri, R.J.; Ward, R.J.; Azevedo Junior, G.W.F. de; Arni, R.K. [UNESP, Sao Jose do Rio Preto, SP (Brazil). Inst. de Biociencias, Letras e Ciencias Exatas; Soares, A.M.; Giglio, J.R. [Sao Paulo Univ., Ribeirao Preto, SP (Brazil). Escola de Medicina

    1997-12-31

    Full text. Phospho lipases A2 (PLA{sub 2}) are small enzymes that specifically hydrolysed the sn-2 ester bond of phospholipids, preferentially in lamellar or micellar aggregates at membrane surfaces. These enzymes are widely distributed in nature and have been extensively studied. Toxic proteins from venoms from Bothrops species include catalytically active PLA{sub 2}s and calcium independent PLA{sub 2L}ys 49 homologues. The substitution of Asp49 by Lys greatly diminishes the ability of these PLA{sub 2} to bind calcium, an ion that plays a critical role in the stabilization of the tetrahedral transition state intermediate in the catalytic mechanism. The Lys 49 PLA{sub 2} homologues and therefore catalytically inactive yet maintain cytolytic and myotoxic activities and furthermore retain the ability to disrupt the integrity of both plasma membranes and model lipid bilayers by a poorly understood Ca {sup 2+} independente mechanism. Lys49 PLA{sub 2} homologues demonstrate a specific toxic activity against skeletal muscle, affecting only muscle fibers and leaving other tissue structure such as connective tissue, nerves and vessels essentially unharmed. In order to improve our understanding of the molecular basis of the myotoxic and Ca {sup 2+} -independent membrane damaging activities, we have determined the crystal structure of Pr TX-I, a Lys49 variant from the venom of B. pirajai. The model presented has been determined at 2.8 angstrom resolution and refined to a crystallographic residual of 19.7% (R{sub free}=29.7%). (author)

  3. Stable prenucleation calcium carbonate clusters

    OpenAIRE

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-01-01

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate...

  4. Crystal structure of a polymeric calcium levulinate dihydrate: catena-poly[[diaquacalcium]-bis(μ2-4-oxobutanoato

    Directory of Open Access Journals (Sweden)

    Ananda S. Amarasekara

    2015-05-01

    Full Text Available In the title calcium levulinate complex, [Ca(C5H7O32(H2O2]n, the Ca2+ ion lies on a twofold rotation axis and is octacoordinated by two aqua ligands and six O atoms from four symmetry-related carboxylate ligands, giving a distorted square-antiprismatic coordination stereochemistry [Ca—O bond-length range = 2.355 (1–2.599 (1 Å]. The levulinate ligands act both in a bidentate carboxyl O,O′-chelate mode and in a bridging mode through one carboxyl O atom with an inversion-related Ca2+ atom, giving a Ca...Ca separation of 4.0326 (7 Å. A coordination polymeric chain structure is generated, extending along the c-axial direction. The coordinating water molecules act as double donors and participate in intra-chain O—H...O hydrogen bonds with carboxyl O atoms, and in inter-chain O—H...O hydrogen bonds with carbonyl O atoms, thus forming an overall three-dimensional structure.

  5. The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box

    Energy Technology Data Exchange (ETDEWEB)

    Nagul, Edward A. [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia); Centre for Aquatic Pollution Identification and Management (CAPIM), The University of Melbourne, Victoria 3010 (Australia); McKelvie, Ian D. [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia); School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL48AA (United Kingdom); Worsfold, Paul [School of Geography, Earth and Environmental Sciences, Plymouth University, Plymouth PL48AA (United Kingdom); Kolev, Spas D., E-mail: s.kolev@unimelb.edu.au [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia); Centre for Aquatic Pollution Identification and Management (CAPIM), The University of Melbourne, Victoria 3010 (Australia)

    2015-08-26

    The molybdenum blue reaction, used predominantly for the determination of orthophosphate in environmental waters, has been perpetually modified and re-optimised over the years, but this important reaction in analytical chemistry is usually treated as something of a 'black box' in the analytical literature. A large number of papers describe a wide variety of reaction conditions and apparently different products (as determined by UV–visible spectroscopy) but a discussion of the chemistry underlying this behaviour is often addressed superficially or not at all. This review aims to rationalise the findings of the many 'optimised' molybdenum blue methods in the literature, mainly for environmental waters, in terms of the underlying polyoxometallate chemistry and offers suggestions for the further enhancement of this time-honoured analytical reaction. - Highlights: • Molybdenum blue chemistry for orthophosphate determination is discussed. • The choice of reductant determines the blue product(s) obtained. • Mechanisms are described for various additive and subtractive interferents. • The choice of strong mineral acid for the reaction should be considered. • Detailed recommendations are made for method optimisation.

  6. Removal of dissolved humic acid from water by photocatalytic oxidation using a silver orthophosphate semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Hatakeyama, Keisuke, E-mail: hatakeyamak@pref.tottori.jp [Tottori Prefectural Institute of Public Health and Environmental Science, 526-1, Minamidani, Yurihama-cho, Tottori 682-0704 (Japan); Okuda, Masukazu; Kuki, Takahiro [Tottori Prefectural Institute of Public Health and Environmental Science, 526-1, Minamidani, Yurihama-cho, Tottori 682-0704 (Japan); Esaka, Takao [Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Minami 4-101, Koyama-cho, Tottori 680-8552 (Japan)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► The photocatalytic property of a silver orthophosphate (Ag{sub 3}PO{sub 4}) was investigated for humic acid degradation. ► The Ag{sub 3}PO{sub 4} shows high photocatalytic activity under visible light. ► The photocatalytic activity was greatly improved by employing the precipitation method. -- Abstract: In order to remove dissolved organic matter such as humic acid from water, a silver orthophosphate (Ag{sub 3}PO{sub 4}) was newly employed as a heterogeneous photocatalyst. Here, Ag{sub 3}PO{sub 4} was prepared by simple ion-exchange and precipitation methods, and the physico-chemical properties were characterized by X-ray diffraction, ultraviolet–visible diffuse reflectance spectroscopy, scanning electron microscopy, particle distribution measurements and Brunauer–Emmett–Teller (BET) analysis. The degradation of humic acid was faster over Ag{sub 3}PO{sub 4} catalyst than over conventional TiO{sub 2} (P-25). The total photocatalytic properties were improved by employing not an ion-exchange method but a precipitation method; humic acid degradation was performed with a removal ratio of dissolved organic carbon of 75% under visible light (λ = 451 nm) for 2-h irradiation.

  7. Effect of aqueous extract of “eryngium campestre” on the prevention of pathologic alterations caused by calcium oxalate crystals induced by ethylene glycol in the cortex and medulla of rats’ kidneys

    OpenAIRE

    Sajjad Esmaeili; Mehran Falahpour amiry; Abdolghader Taene; Mina Hemmati; Mohammad Malekaneh

    2017-01-01

    Background and Aim: Due to the effects of herbs in the prevention of kidney stones, the present study aimed at assessing the effect of aqueous eryngium campestre on the prevention of pathologic alterations caused by calcium oxalate crystals induced by ethylene glycol in the cortex and medulla of rats’kidneys. Materials and Methods: To conduct the study 40 male Wistar rats, weighing 200 – 250 gr were randomly divided into 5 equal groups; i.e. the healthy control group that just ...

  8. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

  9. The molybdenum blue reaction for the determination of orthophosphate revisited: Opening the black box.

    Science.gov (United States)

    Nagul, Edward A; McKelvie, Ian D; Worsfold, Paul; Kolev, Spas D

    2015-08-26

    The molybdenum blue reaction, used predominantly for the determination of orthophosphate in environmental waters, has been perpetually modified and re-optimised over the years, but this important reaction in analytical chemistry is usually treated as something of a 'black box' in the analytical literature. A large number of papers describe a wide variety of reaction conditions and apparently different products (as determined by UV-visible spectroscopy) but a discussion of the chemistry underlying this behaviour is often addressed superficially or not at all. This review aims to rationalise the findings of the many 'optimised' molybdenum blue methods in the literature, mainly for environmental waters, in terms of the underlying polyoxometallate chemistry and offers suggestions for the further enhancement of this time-honoured analytical reaction. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Quadrupole splitting and Eu partial lattice dynamics in europium orthophosphate EuPO {sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Klobes, B., E-mail: b.klobes@fz-juelich.de [JARA-FIT - Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI (Germany); Arinicheva, Y., E-mail: y.arinicheva@fz-juelich.de; Neumeier, S., E-mail: s.neumeier@fz-juelich.de [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-6) Nuclear Waste Management and Reactor Safety (Germany); Simon, R. E., E-mail: r.simon@fz-juelich.de; Jafari, A., E-mail: a.jafari@fz-juelich.de [JARA-FIT - Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI (Germany); Bosbach, D., E-mail: d.bosbach@fz-juelich.de [Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research (IEK-6) Nuclear Waste Management and Reactor Safety (Germany); Hermann, R. P., E-mail: hermannrp@ornl.gov [JARA-FIT - Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS and Peter Grünberg Institute PGI (Germany)

    2016-12-15

    Hyperfine interactions in europium orthophosphate EuPO{sub 4} were investigated using {sup 151}Eu Mössbauer spectroscopy from 6 to 300 K. The value of the quadrupole splitting and the asymmetry parameter were refined and further substantiated by nuclear forward scattering data obtained at room temperature. The temperature dependence of the relative absorption was modeled with an Eu specific Debye temperature of 221(1) K. Eu partial lattice dynamics were probed by means of nuclear inelastic scattering and the mean force constant, the Lamb-Mössbauer factor, the internal energy, the vibrational entropy, the average phonon group velocity were calculated using the extracted density of phonon states. In general, Eu specific vibrations are characterized by rather small phonon energies and contribute strongly to the total entropy of the system. Although there is no classical Debye like behavior at low vibrational energies, the average phonon group velocity can be reasonably approximated using a linear fit.

  11. Influence des ions étrangers et de la matière organique sur la cristallisation des carbonates de calcium Influence of Foreign Ions and of Organic Matter on the Crystallization of Calcium Carbonates

    Directory of Open Access Journals (Sweden)

    Cailleau P.

    2006-11-01

    examines the influence of foreign ions and organic matter on the ger-mination and growth of calcium carbonates.The main results obtained can be summed up as follows:a Concerning Foreign Ions.Their action generally results in:- an increase in germination time and a reduction in the growth rate of CaC03 crystals:- the appearance of special facies for some of the minerals formed: - the inhibition of transformation from one variety ta another.A classification by order of increasing efficiency is obtained: - approximately zero action: K+, CI-;- moderate action: Bot+, Na+, A13+, Cul+, Sr 2+, S04-, P04- . - dominant action of Mg'+.b For Organic Matter.Citric acid and, ta a lesser extent, tartaric acid are the only ones ta have an appre ciable influence, moreover an influence which is similar to thot of foreign ions with regard ta kinetics of CaCO3 germination and growth.The adsorption of some of these products also results in special facies of the minerals formed and eventually in the inhibition of transformations from one variety ta another

  12. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    Science.gov (United States)

    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.

  13. Calcium Carbonate

    Science.gov (United States)

    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 ...

  14. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  15. Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

    Science.gov (United States)

    Kevin T. Smith; Walter C. Shortle; Jon H. Connolly; Rakesh Minocha; Jody Jellison

    2009-01-01

    Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of...

  16. Biosorption and retention of orthophosphate onto Ca(OH)2-pretreated biomass of Phragmites sp.

    Science.gov (United States)

    Markou, Giorgos; Mitrogiannis, Dimitris; Muylaert, Koenraad; Çelekli, Abuzer; Bozkurt, Hüseyin

    2016-07-01

    The biosorption of phosphorus in the form of orthophosphate (Po) from wastewater using biomass as the sorbent is of potential importance because the Po-loaded biomass could be applied in the agricultural sector as fertilizer and soil conditioner. However, biomass generally displays a very low affinity for Po sorption and therefore biomass surface modification is required. In the present study, the biomass (as model grinded leaves of Phragmites sp. were used) was pretreated with Ca(OH)2 to enhance Po biosorption capacity (qe). The results indicate that the alkaline pretreatment resulted in a modification of surface functional groups. It was concluded that the main sorption mechanisms were ligand exchange and electrostatic attraction. A series of experiments were conducted to investigate the performance of the pretreated biomass for Po uptake under various conditions. Isotherm and thermodynamic studies were also applied and analyzed. The biosorption process was best described by the pseudo-second order kinetic model and Langmuir isotherm, which gave a qmax of 12.27mgP/g at 25°C and pH7. The Ca(OH)2 treated Phragmites biomass applied in this study for Po recovery may present some potential advantages in terms of costs and environmental impact. Copyright © 2016. Published by Elsevier B.V.

  17. Identifying pathways and processes affecting nitrate and orthophosphate inputs to streams in agricultural watersheds.

    Science.gov (United States)

    Tesoriero, Anthony J; Duff, John H; Wolock, David M; Spahr, Norman E; Almendinger, James E

    2009-01-01

    Understanding nutrient pathways to streams will improve nutrient management strategies and estimates of the time lag between when changes in land use practices occur and when water quality effects that result from these changes are observed. Nitrate and orthophosphate (OP) concentrations in several environmental compartments were examined in watersheds having a range of base flow index (BFI) values across the continental United States to determine the dominant pathways for water and nutrient inputs to streams. Estimates of the proportion of stream nitrate that was derived from groundwater increased as BFI increased. Nitrate concentration gradients between groundwater and surface water further supported the groundwater source of nitrate in these high BFI streams. However, nitrate concentrations in stream-bed pore water in all settings were typically lower than stream or upland groundwater concentrations, suggesting that nitrate discharge to streams was not uniform through the bed. Rather, preferential pathways (e.g., springs, seeps) may allow high nitrate groundwater to bypass sites of high biogeochemical transformation. Rapid pathway compartments (e.g., overland flow, tile drains) had OP concentrations that were typically higher than in streams and were important OP conveyers in most of these watersheds. In contrast to nitrate, the proportion of stream OP that is derived from ground water did not systematically increase as BFI increased. While typically not the dominant source of OP, groundwater discharge was an important pathway of OP transport to streams when BFI values were very high and when geochemical conditions favored OP mobility in groundwater.

  18. Stable prenucleation calcium carbonate clusters.

    Science.gov (United States)

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-12-19

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate in fact contains stable prenucleation ion clusters forming even in undersaturated solution. The cluster formation can be characterized by means of equilibrium thermodynamics, applying a multiple-binding model, which allows for structural preformation. Stable clusters are the relevant species in calcium carbonate nucleation. Such mechanisms may also be important for the crystallization of other minerals.

  19. CCDC 1420585: Experimental Crystal Structure Determination : catena-[(mu-22,25-bis(4-carboxyphenyl)[11,21:24,31-terphenyl]-14,34-dicarboxylato)-calcium ethane

    KAUST Repository

    Plonka, Anna M.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  20. CCDC 1420584: Experimental Crystal Structure Determination : catena-[(mu-22,25-bis(4-carboxyphenyl)[11,21:24,31-terphenyl]-14,34-dicarboxylato)-calcium ethylene

    KAUST Repository

    Plonka, Anna M.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  1. CCDC 1420583: Experimental Crystal Structure Determination : catena-[(mu-22,25-bis(4-carboxyphenyl)[11,21:24,31-terphenyl]-14,34-dicarboxylato)-calcium acetylene

    KAUST Repository

    Plonka, Anna M.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  2. Sources and mechanisms of nitrate and orthophosphate transport in urban stormwater runoff from residential catchments.

    Science.gov (United States)

    Yang, Yun-Ya; Toor, Gurpal S

    2017-04-01

    Nutrients export from residential catchments contributes to water quality impairment in urban water bodies. We investigated the concentrations, transport mechanisms, and sources of nitrate-nitrogen (NO 3 -N) and orthophosphate-phosphorus (PO 4 -P) in urban stormwater runoff generated in residential catchments in Tampa Bay, Florida, United States. Street runoff samples, collected over 21 storm events, were supplemented with rainfall and roof runoff samples from six representative residential catchments. Samples were analyzed for N and P forms, N and oxygen (O) isotopes of nitrate (δ 18 O-NO 3 - and δ 15 N-NO 3 - ), and δ 18 O and hydrogen (δD) isotopes of water (H 2 O). We found that the main NO 3 -N source in street runoff was atmospheric deposition (range: 35-64%), followed by chemical N fertilizers (range: 1-39%), and soil and organic N (range: 7-33%), whereas PO 4 -P in the street runoff likely originated from erosion of soil particles and mineralization from organic materials (leaves, grass clippings). The variability in the sources and concentrations of NO 3 -N and PO 4 -P across catchments is attributed to different development designs and patterns, use of various fill materials during land development, and landscaping practices. This data can be useful to develop strategies to offset the impacts of urban development (e.g., designs and patterns resulting in variable impervious areas) and management (e.g., fertilizer use, landscaping practices) on NO 3 -N and PO 4 -P transport in urban residential catchments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Effects of polyphosphates and orthophosphate on the dissolution and transformation of ZnO nanoparticles.

    Science.gov (United States)

    Wan, Biao; Yan, Yupeng; Tang, Yuanzhi; Bai, Yuge; Liu, Fan; Tan, Wenfeng; Huang, Qiaoyun; Feng, Xionghan

    2017-06-01

    The fate and toxicity of zinc oxide nanoparticles (ZnO NPs) in nature are affected by solution chemistry such as pH, anions, and natural organic matter (NOM). Inorganic polyphosphates are environmentally ubiquitous phosphorus (P) species that may change the speciation and environmental fate of ZnO NPs. In this study, the interactions of polyphosphates with ZnO NPs and the impacts on ZnO NP dissolution and transformation were investigated and compared with orthophosphate (P1). The results revealed that pyrophosphate (P2), tripolyphosphate (P3), and hexametaphosphate (P6) enhanced whereas P1 inhibited the dissolution of ZnO NPs. In addition, P1, P2, and P3 promoted the transformation of ZnO NPs into zinc phosphate (Zn-P) precipitates via interactions with dissolved Zn(2+). However, P6-promoted ZnO NP dissolution was through the formation of soluble Zn-P complexes due to the strong capability of P6 to chelate with Zn(2+). The transformation of ZnO NPs in the presence of P3 was affected by reaction time, pH, and P/Zn molar ratio. P3 first formed inner-sphere surface complexes on ZnO NPs, which gradually transformed into crystalline Zn2HP3O10(H2O)6 precipitates. This study provided a new perspective for understanding the reactivity of various forms of inorganic phosphate species with ZnO NPs in the natural environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Significant accumulation of C(4)-specific pyruvate, orthophosphate dikinase in a C(3) plant, rice.

    Science.gov (United States)

    Fukayama, H; Tsuchida, H; Agarie, S; Nomura, M; Onodera, H; Ono, K; Lee, B H; Hirose, S; Toki, S; Ku, M S; Makino, A; Matsuoka, M; Miyao, M

    2001-11-01

    The C(4)-Pdk gene encoding the C(4) enzyme pyruvate, orthophosphate dikinase (PPDK) of maize (Zea mays cv Golden Cross Bantam) was introduced into the C(3) plant, rice (Oryza sativa cv Kitaake). When the intact maize C(4)-Pdk gene, containing its own promoter and terminator sequences and exon/intron structure, was introduced, the PPDK activity in the leaves of some transgenic lines was greatly increased, in one line reaching 40-fold over that of wild-type plants. In a homozygous line, the PPDK protein accounted for 35% of total leaf-soluble protein or 16% of total leaf nitrogen. In contrast, introduction of a chimeric gene containing the full-length cDNA of the maize PPDK fused to the maize C(4)-Pdk promoter or the rice Cab promoter only increased PPDK activity and protein level slightly. These observations suggest that the intron(s) or the terminator sequence of the maize gene, or a combination of both, is necessary for high-level expression. In maize and transgenic rice plants carrying the intact maize gene, the level of transcript in the leaves per copy of the maize C(4)-Pdk gene was comparable, and the maize gene was expressed in a similar organ-specific manner. These results suggest that the maize C(4)-Pdk gene behaves in a quantitatively and qualitatively similar way in maize and transgenic rice plants. The activity of the maize PPDK protein expressed in rice leaves was light/dark regulated as it is in maize. This is the first reported evidence for the presence of an endogenous PPDK regulatory protein in a C(3) plant.

  5. Biomimetic calcium phosphate coatings on Ti6Al4V: a crystal growth study of octacalcium phosphate and inhibition by Mg2+ and HCO3−

    NARCIS (Netherlands)

    Barrère, F.; Layrolle, P.; van Blitterswijk, Clemens; de Groot, K.

    1999-01-01

    The biomimetic approach for coating metal implants allows the deposition of new calcium phosphate (Ca-P) phases. Films elaborated at physiological conditions might have structures closer to bone mineral than hydroxyl-apatite (HA) plasma-sprayed coatings. In this study, different Ca-P coatings have

  6. Influence d'impuretés sur les processus de cristallisation de l'orthophosphate monopotassique (KDP) en solution aqueuse

    OpenAIRE

    Triboulet, Philippe

    1990-01-01

    212 pages; No English abstract; La précipitation de l'orthophosphate monopotassique (KDP) à partir de ses solutions aqueuses sursaturées est la résultante de trois processus: germination primaire, croissance et germination secondaire que la présente étude essaie de discerner. Il est prouvé que l'aluminium introduit sous forme d'ajouts de chlorure d'aluminium a une influence sur les trois étapes précédentes et sur la morphologie des cristaux formes. Un intérêt tout particulier est porte à la g...

  7. A multisyringe flow-through sequential extraction system for on-line monitoring of orthophosphate in soils and sediments

    DEFF Research Database (Denmark)

    Buanuam, Janya; Miró, Manuel; Hansen, Elo Harald

    2007-01-01

    A fully automated flow-through microcolumn fractionation system with on-line post-extraction derivatization is proposed for monitoring of orthophosphate in solid samples of environmental relevance. The system integrates dynamic sequential extraction using 1.0 mol l-1 NH4Cl, 0.1 mol l-1 NaOH and 0...... P l-1 in NH4Cl and NaOH media and 15 mg P l-1 whenever HCl is utilized as extractant for both the HL and SMT protocols....

  8. Heat capacity and thermodynamic functions of thulium orthophosphate TmPO4 in the range of 10-1350 K

    Science.gov (United States)

    Ryumin, M. A.; Gurevich, V. M.; Khoroshilov, A. V.; Tyurin, A. V.; Gavrichev, K. S.

    2017-12-01

    The heat capacity of TmPO4 in temperature ranges of 9.11-346.05 and 304.6-1344.6 K is measured via adiabatic and differential scanning calorimetry, respectively. The measurement data are used to calculate the temperature dependences of the heat capacity, entropy, change in enthalpy, and reduced Gibbs energy of TmPO4 in the range of 10-1344 K. The Gibbs energy of formation of thulium orthophosphate from elements Δf G 0(298.15 K) is determined.

  9. Cytochrome c3 from Desulfovibrio gigas: crystal structure at 1.8 A resolution and evidence for a specific calcium-binding site.

    OpenAIRE

    Matias, P. M.; Morais, J.; Coelho, R.; Carrondo, M. A.; Wilson, K. Van; Dauter, Z.; Sieker, L

    1996-01-01

    Crystals of the tetraheme cytochrome c3 from sulfate-reducing bacteria Desulfovibrio gigas (Dg) (MW 13 kDa, 111 residues, four heme groups) were obtained and X-ray diffraction data collected to 1.8 A resolution. The structure was solved by the method of molecular replacement and the resulting model refined to a conventional R-factor of 14.9%. The three-dimensional structure shows many similarities to other known crystal structures of tetraheme c3 cytochromes, but it also shows some remarkable...

  10. Effect of NH4-N/P and Ca/P molar ratios on the reactive crystallization of calcium phosphates for phosphorus recovery from wastewater

    DEFF Research Database (Denmark)

    Vasenko, Liubov; Qu, Haiyan

    2017-01-01

    In this work, the effects of operational parameters, initial phosphorus concentration and molar ratios of Ca/P and NH4-N/P (further in the text N/P), on the nature and purity of precipitated phosphorus products have been investigated in an artificial system that mimics the supernatant in wastewater.......7 – 6.3 and at pH lower than 4.7 the mixtures of DCPD and HAp were obtained. It was observed that N/P ratio affects not only the metastable zone width but also the kinetics of crystal growth for both DCPD and HAp: the higher the N/P ratio, the lower is the growth rate for both P-products. Investigation...... of the effect of Ca/P and N/P ratios on the nucleation and crystal growth of DCPD in batch crystallization experiment was performed. It showed that at high supersaturation lev-el, crystals with larger median size can be obtained at higher N/P ratio despite the negative effects of N/P ratio on the growth rate...

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

    Science.gov (United States)

    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.

  12. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    Science.gov (United States)

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Growth of large detector crystals. CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

    Boatner, L.A. [Oak Ridge National Lab., TN (United States); Samuelson, S. [Deltronic Crystal Industries, Dover, NJ (United States)

    1997-06-18

    In the course of a collaborative research effort between L.A. Boatner of Oak Ridge National Laboratory and Prof. Alex Lempicki of the Department of Chemistry of Boston University, a new highly efficient and very fast scintillator for the detection of gamma-rays was discovered. This new scintillator consists of a single crystal of lutetium orthophosphate (LuPO{sub 4}) to which a small percentage of trivalent cerium is added as an activator ion. The new lutetium orthophosphate-cerium scintillator was found to be superior in performance to bismuth germanium oxide--a material that is currently widely used as a gamma-ray detector in a variety of medical, scientific, and technical applications. Single crystals of LuPO{sub 4} and related rare-earth orthophosphates had been grown for a number of years in the ORNL Solid State Division prior to the discovery of the efficient gamma-ray-scintillation response of LuPO{sub 4}:Ce. The high-temperature-solvent (flux-growth) method used for the growth of these crystals was capable of producing crystals in sizes that were adequate for research purposes but that were inadequate for commercial-scale production and widespread application. The CRADA between ORNL and Deltronic Crystal Industries of Dover, NJ was undertaken for the purpose of investigating alternate approaches, such as top-seeded-solution growth, to the growth of LuPO{sub 4}:Ce scintillator crystals in sizes significantly larger than those obtainable through the application of standard flux-growth methods and, therefore, suitable for commercial sales and applications.

  14. Phosphocitrate inhibits mitochondrial and cytosolic accumulation of calcium in kidney cells in vivo.

    OpenAIRE

    Tew, W P; Malis, C D; Howard, J. E.; Lehninger, A L

    1981-01-01

    Synthetic 3-phosphocitrate, an extremely potent inhibitor of calcium phosphate crystallization as determined in a nonbiological physical-chemical assay, has many similarities to a mitochondrial factor that inhibits crystallization of nondiffracting amorphous calcium phosphate. In order to determine whether phosphocitrate can prevent uptake and crystallization of calcium phosphate in mitochondria in vivo, it was administered intraperitoneally to animals given large daily doses of calcium gluco...

  15. Mechanochemical Effects on the Synthesis of Copper Orthophosphate and cyclo-Tetraphosphate Bulks by the Hydrothermal Hot Pressing Method

    Directory of Open Access Journals (Sweden)

    Isao Tanaka

    2009-01-01

    Full Text Available Copper orthophosphate, Cu3(PO42, and cyclo-tetraphosphates, Cu2P4O12, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and milled samples were characterized by X-ray diffraction (XRD and Fourier transform infrared (FT-IR spectroscopy. SEM images, particle size distribution, specific surface area, UV-Vis reflectance spectra were also used to evaluate the materials. The un-milled and milled materials were used to fabricate copper phosphate bulks by a hydrothermal hot pressing method. The influence of powder condition on the sintering behavior of the copper phosphates was studied.

  16. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  17. Crystal structure of calpain-3 penta-EF-hand (PEF) domain - a homodimerized PEF family member with calcium bound at the fifth EF-hand.

    Science.gov (United States)

    Partha, Sarathy K; Ravulapalli, Ravikiran; Allingham, John S; Campbell, Robert L; Davies, Peter L

    2014-07-01

    Calpains are Ca(2+) dependent intracellular cysteine proteases that cleave a wide range of protein substrates to help implement Ca(2+) signaling in the cell. The major isoforms of this enzyme family, calpain-1 and calpain-2, are heterodimers of a large and a small subunit, with the main dimer interface being formed through their C-terminal penta-EF hand (PEF) domains. Calpain-3, or p94, is a skeletal muscle-specific isoform that is genetically linked to limb-girdle muscular dystrophy. Biophysical and modeling studies with the PEF domain of calpain-3 support the suggestion that full-length calpain-3 exists as a homodimer. Here, we report the crystallization of calpain-3's PEF domain and its crystal structure in the presence of Ca(2+) , which provides evidence for the homodimer architecture of calpain-3 and supports the molecular model that places a protease core at either end of the elongated dimer. Unlike other calpain PEF domain structures, the calpain-3 PEF domain contains a Ca(2+) bound at the EF5-hand used for homodimer association. Three of the four Ca(2+) -binding EF-hands of the PEF domains are concentrated near the protease core, and have the potential to radically change the local charge within the dimer during Ca(2+) signaling. Examination of the homodimer interface shows that there would be steric clashes if the calpain-3 large subunit were to try to pair with a calpain small subunit. Database Structural data are available in the Protein Data Bank database under accession number 4OKH. © 2014 FEBS.

  18. Crystal structure of calpain-3 penta-EF-hand (PEF) domain - a homodimerized PEF family member with calcium bound at the fifth EF-hand

    Energy Technology Data Exchange (ETDEWEB)

    Partha, Sarathy K.; Ravulapalli, Ravikiran; Allingham, John S.; Campbell, Robert L.; Davies, Peter L. [Queens

    2014-08-21

    Calpains are Ca2+dependent intracellular cysteine proteases that cleave a wide range of protein substrates to help implement Ca2+ signaling in the cell. The major isoforms of this enzyme family, calpain-1 and calpain-2, are heterodimers of a large and a small subunit, with the main dimer interface being formed through their C-terminal penta-EF hand (PEF) domains. Calpain-3, or p94, is a skeletal muscle-specific isoform that is genetically linked to limb-girdle muscular dystrophy. Biophysical and modeling studies with the PEF domain of calpain-3 support the suggestion that full-length calpain-3 exists as a homodimer. Here, we report the crystallization of calpain-3's PEF domain and its crystal structure in the presence of Ca2+, which provides evidence for the homodimer architecture of calpain-3 and supports the molecular model that places a protease core at either end of the elongated dimer. Unlike other calpain PEF domain structures, the calpain-3 PEF domain contains a Ca2+ bound at the EF5-hand used for homodimer association. Three of the four Ca2+-binding EF-hands of the PEF domains are concentrated near the protease core, and have the potential to radically change the local charge within the dimer during Ca2+ signaling. Examination of the homodimer interface shows that there would be steric clashes if the calpain-3 large subunit were to try to pair with a calpain small subunit.

  19. Synthesis and characterization of calcium beta-diketonate complexes. X-ray crystal and molecular structures of: [{Ca(tmhd)2}2(18-crown-6)], [Ca(dpp)2(thf)2] and [Ca(dpp)2(triglyme)].

    Science.gov (United States)

    El Habra, Naida; Benetollo, Franco; Casarin, Maurizio; Bolzan, Marco; Sartori, Andrea; Rossetto, Gilberto

    2010-09-14

    Reactions of 2,2,6,6-tetramethyl-3,5-heptanedione (Htmhd), 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (Hhfa) or 1,3-diphenyl-1,3-propanedione (Hdpp) with calcium methoxide in hexane or toluene afford the corresponding known oligomeric beta-diketonates: [Ca(3)(tmhd)(6)], [{Ca(hfa)(2)}(n)] and [{Ca(dpp)(2)}(n)]. The complexes react with tetrahydrofuran, 2,5,8,11-tetraoxadodecane (triglyme) or 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) leading to the formation of the new mononuclear [Ca(dpp)(2)(thf)(2)], [Ca(dpp)(2)(triglyme)] and dinuclear [{Ca(dpp)(2)}(2)(18-crown-6)] and [{Ca(tmhd)(2)}(2)(18-crown-6)] adducts. The obtained complexes were characterized by elemental analyses, IR, (1)H and (13)C NMR spectroscopies; moreover, single crystal X-ray diffraction measurements were also carried out for: [{Ca(tmhd)(2)}(2)(18-crown-6)], [Ca(dpp)(2)(thf)(2)] and [Ca(dpp)(2)(triglyme)].

  20. Protein-Mediated Precipitation of Calcium Carbonate.

    Science.gov (United States)

    Polowczyk, Izabela; Bastrzyk, Anna; Fiedot, Marta

    2016-11-22

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

  1. The crystal structure of the calcium-bound con-G[Q6A] peptide reveals a novel metal-dependent helical trimer

    Energy Technology Data Exchange (ETDEWEB)

    Cnudde, Sara E.; Prorok, Mary; Jia, Xaofei; Castellino, Francis J.; Geiger, James H. (MSU); (Notre)

    2012-02-15

    The ability to form and control both secondary structure and oligomerization in short peptides has proven to be challenging owing to the structural instability of such peptides. The conantokin peptides are a family of {gamma}-carboxyglutamic acid containing peptides produced in the venoms of predatory sea snails of the Conus family. They are examples of short peptides that form stable helical structures, especially in the presence of divalent cations. Both monomeric and dimeric conantokin peptides have been identified and represent a new mechanism of helix association, 'the metallozipper motif' that is devoid of a hydrophobic interface between monomers. In the present study, a parallel/antiparallel three-helix bundle was identified and its crystal structure determined at high resolution. The three helices are almost perfectly parallel and represent a novel helix-helix association. The trimer interface is dominated by metal chelation between the three helices, and contains no interfacial hydrophobic interactions. It is now possible to produce stable monomeric, dimeric, or trimeric metallozippers depending on the peptide sequence and metal ion. Such structures have important applications in protein design.

  2. Study of Factors Related to Magnetic Treatment of Calcium Carbonate Saturated Water

    National Research Council Canada - National Science Library

    Lambert, Kevin

    1998-01-01

    ..., calcium carbonate concentration and number of magnetic device attached. XRD of crystals gave relative proportions of calcite and aragonite present and XRF measured transition metals and elements known to substitute for calcium in scale...

  3. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  4. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  5. Ca2+-exchange in layered zirconium orthophosphate, α-ZrP: Chemical study and potential application for zinc corrosion inhibition

    Science.gov (United States)

    Bouali, Imane; Rocca, Emmanuel; Veys-Renaux, Delphine; Rhouta, Benaissa; Khalil, Aziza; Aït Aghzzaf, Ahmed

    2017-11-01

    The control of the corrosion phenomenon occurring at the metal interface requires the development of new non-toxic anticorrosion additives. For this purpose, zirconium orthophosphate compounds (Zr(HPO4)2,H2O noted α-ZrP) were synthesized by both hydrothermal and refluxing methods The Ca2+-cationic exchange in the layered structure is kinetically favoured by low crystallinity of α-ZrP synthesized by refluxing process, and leads to the formation of CaZr(PO4)2,4H2O, noted Ca2+-ZrP. The H+/Ca2+ exchange mechanism is mainly triggered by acid-base considerations, and especially the pKa of α-ZrP/Ca2+-ZrP acid-base couple (evaluated to 2.5). Both compounds are acidic compounds by internal exchangeable H+ for α-ZrP and surface protons for Ca2+-ZrP, and can be used as potential inhibitors of zinc corrosion. Electrochemical measurements show that Ca2+-ZrP compounds dispersed in the NaCl electrolyte buffer the pH value over a long time and therefore allow controlling the corrosion rate of zinc.

  6. The influence of Al{sub 2}O{sub 3}, MgO and ZnO on the crystallization characteristics and properties of lithium calcium silicate glasses and glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Salman, S.M. [Glass Research Department, National Research Centre, El-Behoos St., Dokki, Cairo (Egypt)], E-mail: saadmoghazy@hotmail.com; Darwish, H.; Mahdy, E.A. [Glass Research Department, National Research Centre, El-Behoos St., Dokki, Cairo (Egypt)

    2008-12-20

    The crystallization characteristics of glasses based on the Li{sub 2}O-CaO-SiO{sub 2} eutectic (954 {+-} 4 deg. C) system containing Al{sub 2}O{sub 3}, MgO and ZnO has been investigated by differential thermal analysis (DTA), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The partial replacement of Li{sub 2}O by Al{sub 2}O{sub 3} and CaO by MgO or ZnO in the studied glass-ceramics led to the development of different crystalline phase assemblages, including lithium meta- and di-silicates, lithium calcium silicates, {alpha}-quartz, diopside, clinoenstatite, wollastonite, {beta}-eucryptite ss, {beta}-spodumene, {alpha}-tridymite, lithium zinc orthosilicate, hardystonite and willemite using various heat-treatment processes. The dilatometric thermal expansion of the glasses and their corresponding glass-ceramics were determined. A wide range of thermal expansion coefficient values were obtained for the investigated glasses and their corresponding crystalline products. The thermal expansion coefficients of the investigated glasses were decreased by Al{sub 2}O{sub 3}, MgO or ZnO additions. The {alpha}-values of the investigated glasses were ranged from (+18) to (+108) x 10{sup -7} K{sup -1} (25-300 deg. C), while those of the glass-ceramics were (+3) to (+135) x 10{sup -7} K{sup -1} (25-700 deg. C). The chemical durability of the glass-ceramics, towards the attack of 0.1N HCl solution, was markedly improved by Al{sub 2}O{sub 3} with MgO replacements. The composition containing 11.5 mol% Al{sub 2}O{sub 3} and 6.00 mol% MgO exhibited low thermal expansion values and good chemical durability.

  7. Role of the organic matter in calcium oxalate lithiasis.

    Science.gov (United States)

    Grases, Felix; Isern, Bernat; Perello, Joan; Costa-Bauza, Antonia

    2005-05-01

    Urine contains variable amounts of organic matter derived from cell degradation. The cellular detritus is composed by membranous and cytosolic glycoproteins, etc. The aim of this paper was to study the role of organic matter in calcium oxalate crystal development and to evaluate the action of some crystallization inhibitors on this process. Crystallization studies were carried out on urine in stagnant urine as well as under flow conditions, in presence and absence of cellular debris. Low amounts of cellular debris (when batch conditions were used), exhibited some inhibitory activity on heterogeneous nucleation of calcium oxalate monohydrate crystals, probably due to glycoproteins. Increasing amounts of cellular debris, however, promoted the nucleation of calcium oxalate monohydrate crystals. When cellular debris was retained in a cavity with a urine flow, this organic matter effectively induced the development of primary aggregates of calcium oxalate monohydrate crystals (crystallization range 2.8 mg/h per mg of organic matter). Presence of crystallization inhibitors prevented or minimized crystal development. These findings show that cell debris provides the necessary elements for the development of oxalate crystals and that this process can be effectively inhibited by presence of crystallization inhibitors.

  8. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  9. Acúmulo de ácido oxálico e cristais de cálcio em ectomicorrizas de eucalipto.: II- formação de cristais de oxalato de cálcio induzida por fungos ectomicorrízicos em raízes laterais finas Accumulation of oxalic acid and calcium crystals in ectomycorrhizas of eucalypt.: II- calcium oxalate crystal formation induced by ectomicorrhizal fungi in fine lateral roots

    Directory of Open Access Journals (Sweden)

    Jhon Alexander Zambrano Gonzalez

    2009-06-01

    Full Text Available O eucalipto é eficiente na aquisição de Ca do solo, mas pouco se sabe sobre a participação das ectomicorrizas e dos ácidos orgânicos nesse processo em campo. O acúmulo de cristais de Ca (CaOx foi avaliado em, aproximadamente, 2.100 raízes laterais finas e ectomicorrizas do híbrido de Eucalyptus grandis x Eucalyptus urophylla, cultivado por 2,5 anos em área com topografia típica em meia laranja, com vertente côncavo-convexa, na região de Viçosa, MG. Técnicas de microscopia óptica e microscopia eletrônica de varredura foram usadas para a visualização dos CaOx. Em 73,7 % das raízes, ocorreu abundante acúmulo de drusas e grânulos de CaOx nas células do córtex. A presença conspícua de CaOx foi observada em 56,2 % das ectomicorrizas e em 17,5 % das raízes laterais finas não colonizadas, evidenciando o papel das micorrizas no acúmulo de Ca em eucalipto. A forma predominante dos CaOx foram as drusas nas ectomicorrizas e os grânulos cristalinos nas raízes. Os dez morfotipos de ectomicorrizas observados na área diferiram quanto à presença e à morfologia dos CaOx, o que pode representar distintas capacidades dos fungos ectomicorrízicos em fornecer Ca para a planta hospedeira. A análise da superfície do manto das ectomicorrizas por microscopia eletrônica de varredura não evidenciou a presença de CaOx nessa estrutura, confirmando que, nas condições avaliadas, o acúmulo de cristais limita-se ao córtex radicular. Este é o primeiro relato da ocorrência de CaOx em ectomicorrizas de eucalipto no Brasil, com dados que comprovam que há mecanismos de armazenamento de Ca nas ectomicorrizas em áreas com baixa disponibilidade do elemento.Eucalypt is efficient at taking up Ca from the soil, however little is known about the contribution of ectomycorrhizas and organic acids to this process under field conditions. The accumulation of calcium oxalate crystals (CaOx was evaluated in, approximately, 2,100 fine lateral roots

  10. Mechanical Properties of a Calcium Dietary Supplement, Calcium Fumarate Trihydrate.

    Science.gov (United States)

    Sun, Shijing; Henke, Sebastian; Wharmby, Michael T; Yeung, Hamish H-M; Li, Wei; Cheetham, Anthony K

    2015-12-07

    The mechanical properties of calcium fumarate trihydrate, a 1D coordination polymer considered for use as a calcium source for food and beverage enrichment, have been determined via nanoindentation and high-pressure X-ray diffraction with single crystals. The nanoindentation studies reveal that the elastic modulus (16.7-33.4 GPa, depending on crystallographic orientation), hardness (1.05-1.36 GPa), yield stress (0.70-0.90 GPa), and creep behavior (0.8-5.8 nm/s) can be rationalized in view of the anisotropic crystal structure; factors include the directionality of the inorganic Ca-O-Ca chain and hydrogen bonding, as well as the orientation of the fumarate ligands. High-pressure single-crystal X-ray diffraction studies show a bulk modulus of ∼ 20 GPa, which is indicative of elastic recovery intermediate between small molecule drug crystals and inorganic pharmaceutical ingredients. The combined use of nanoindentation and high-pressure X-ray diffraction techniques provides a complementary experimental approach for probing the critical mechanical properties related to tableting of these dietary supplements.

  11. Coronary Calcium Scan

    Science.gov (United States)

    ... Back To Health Topics / Coronary Calcium Scan Coronary Calcium Scan Also known as Calcium Scan Test A coronary calcium scan is a CT scan of your heart that detects and measures the amount of calcium in the walls of your coronary arteries. Overview ...

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

    Science.gov (United States)

    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.

  13. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  14. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  15. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  16. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  17. Genetically modified Medicago truncatula lacking calcium oxalate has increased calcium bioavailability and partially rescues vitamin D receptor knockout mice phenotypes

    Science.gov (United States)

    How the distribution and sequestered form of plant macro/micro-nutrients influence their bioavailability, and ultimately impact human health, is poorly understood. The legume Medicago truncatula has a portion of its tissue calcium sequestered in the form of the calcium oxalate crystal, which reduces...

  18. Protein-Mediated Precipitation of Calcium Carbonate

    Directory of Open Access Journals (Sweden)

    Izabela Polowczyk

    2016-11-01

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

  19. Protein-Mediated Precipitation of Calcium Carbonate

    Science.gov (United States)

    Polowczyk, Izabela; Bastrzyk, Anna; Fiedot, Marta

    2016-01-01

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

  20. [Synovial fluid crystal identification by electron microscopy].

    Science.gov (United States)

    Nero, Patrícia; Nogueira, Isabel; Vilar, Rui; Pimentão, J Bravo; Branco, Jaime C

    2006-01-01

    In clinical practice crystal identification in synovial fluid is made by polarized light microscopy and with some specific stainings. Nevertheless, sometimes we are unable to identify crystals by these means, either because they are too small or because they are widespread on the fluid. To compare the identification of crystals in synovial fluid from patients with non-infectious monoarthritis but no history of local trauma or articular disease, using polarized light and electronic microscopy. We analized synovial fluid samples from patients with non-infectious monoarthritis and no history of local trauma or articular disease. First we used a polarized light microscope and alizarin red staining. Later we used conventional transmission electron microscopy and energy dispersive spectroscopy, in order to identify and characterize crystals. Fourty-five samples from 23 synovial fluids were analyzed. Under polarized light microscopy we identified crystals on 11 samples: 3 with calcium pyrophosphate crystals, 6 with calcium basic phosphate crystals and 2 with sodium monourate crystals. On the remaining 12 samples we were unable to identify crystals. Samples were then analyzed by conventional transmission electron microscopy and energy dispersive spectroscopy confirming the presence of the previously identified crystals. On the remainig 12 samples we were able to identify calcium basic phosphate crystals. Microcrystals seem to be an universal finding in synovial fluid of patients with osteoarthritis. The prevention of their deposition in joints might contribute to stop joint damage in this disease.

  1. Pseudogout and Calcium Pyrophosphate Disease

    Directory of Open Access Journals (Sweden)

    Andrew Williamson

    2017-01-01

    Full Text Available History of present illness: A 53-year-old male presented with worsening right knee pain and swelling over the past 48 hours. He denied recent trauma to the knee, history of IV drug use, and recent illness. He had no history of diabetes, immunodeficiency, chronic steroids, rheumatologic disease, or knee replacement. He described the pain as sharp, non-radiating, and worse with movement. He was unable to walk due to pain. Significant findings: Radiographs of the knee showed multiple radio-dense lines paralleling the articular surface (see red arrows consistent with calcium pyrophosphate crystal deposition within the joint often seen in calcium pyrophosphate disease (CPPD also known as pseudogout. Discussion: Patients commonly present to the emergency department with non-traumatic joint pain. Arthrocentesis is an important diagnostic tool to evaluate for septic arthritis, gout, or pseudogout. Arthrocentesis can demonstrate crystals or abnormal cell count, gram stain, and culture.[1] In the evaluation of joint pain, plain films are usually obtained to evaluate for fracture, dislocation, effusion, or secondary signs of infection. In this case the classic x-ray supported the diagnosis of CPPD.2 The patient was found to have positively birefringent rhomboid shaped crystals consistent with pseudogout on arthrocentesis. Gram stain and culture were both negative. The patient was discharged with NSAIDs and had significant improvement in symptoms upon follow up with primary care physician in 3 days.

  2. Transformations of calcium sulphates in solidified carbonated volatile fluidized ashes

    Directory of Open Access Journals (Sweden)

    Marian Jacek Łączny

    2017-01-01

    During the investigation it was assumed that calcium carbonate, being poorly water-soluble, would not react with the remaining components of the porous water of the volatile fluidized ash. Crystalline phases of calcium sulphates, anhydrite, gypsum and bassanite occurring in bound volatile fluidized ashes after carbonation demonstrate the possibility of crystallization in the presence of calcium carbonate. In particular, a change in the concentration of bassanite indicates that this phase, as a precursor to the crystallization of gypsum, may play a significant role in the process of binding carbonated volatile ashes.

  3. Calcium carbonate polyamorphism and its role in biomineralization: how many amorphous calcium carbonates are there?

    Science.gov (United States)

    Cartwright, Julyan H E; Checa, Antonio G; Gale, Julian D; Gebauer, Denis; Sainz-Díaz, C Ignacio

    2012-11-26

    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 understood 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. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Calcium precipitate induced aerobic granulation.

    Science.gov (United States)

    Wan, Chunli; Lee, Duu-Jong; Yang, Xue; Wang, Yayi; Wang, Xingzu; Liu, Xiang

    2015-01-01

    Aerobic granulation is a novel biotechnology for wastewater treatment. This study refined existing aerobic granulation mechanisms as a sequencing process including formation of calcium precipitate under alkaline pH to form inorganic cores, followed by bacterial attachment and growth on these cores to form the exopolysaccharide matrix. Mature granules comprised an inner core and a matrix layer and a rim layer with enriched microbial strains. The inorganic core was a mix of different crystals of calcium and phosphates. Functional strains including Sphingomonas sp., Paracoccus sp. Sinorhizobium americanum strain and Flavobacterium sp. attached onto the cores. These functional strains promote c-di-GMP production and the expression by Psl and Alg genes for exopolysaccharide production to enhance formation of mature granules. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. The effect of gamma-ray irradiation on the Mn(II) speciation in Deinococcus radiodurans and the potential role of Mn(II)-orthophosphates.

    Science.gov (United States)

    Bruch, E M; de Groot, A; Un, S; Tabares, L C

    2015-05-01

    D. radiodurans accumulates large quantities of Mn(II), which is believed to form low molecular weight complexes with phosphate and metabolites that protect D. radiodurans from radiation damage. The concentration of Mn(II) species in D. radiodurans during the exponential and stationary phase was determined using high-field EPR and biochemical techniques. In the exponential growth phase cells a large fraction of the manganese was in the form of Mn(II)-orthophosphate complexes. By contrast, the intracellular concentration of these compounds in stationary phase cells was less than 16 μM, while that of Mn superoxide dismutase was 320 μM and that of another, yet unidentified, Mn(II) protein was 250 μM. Stationary cells were found to be equally resistant to irradiation as the exponential cells in spite of having significant lower Mn(II)-orthophosphate concentrations. Gamma irradiation induced no changes in the Mn(II) speciation. During stationary growth phase D. radiodurans favours the production of the two Mn-proteins over low molecular weight complexes suggesting that the latter were not essential for radio-resistance at this stage of growth.

  6. Probable functions and remobilisation of calcium oxalates in Musa L.

    African Journals Online (AJOL)

    Owner

    plantain fruit pulp with distinct intra-amylar crystals; (B) ripened fruit pulp with little or no crystals; (C) over- ripened fruit pulp with ... ripened peels showing reduction in size of the raphide bundles; and (F) over-ripened peel showing apparent lack of raphide ... The process of recycling and/or remobilization of calcium in plants ...

  7. Precipitation of Calcium, Magnesium, Strontium and Barium in Tissues of Four Acacia Species (Leguminosae: Mimosoideae)

    OpenAIRE

    Honghua He; Timothy M Bleby; ERIK J. VENEKLAAS; Hans Lambers; John Kuo

    2012-01-01

    Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glass...

  8. Phase transitions in biogenic amorphous calcium carbonate

    Science.gov (United States)

    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. Substitutions in Calcium Aluminates and Calcium Aluminoferrites.

    Science.gov (United States)

    ALUMINUM COMPOUNDS, *CEMENTS, * CALCIUM COMPOUNDS, * FERRITES , *SCIENTIFIC RESEARCH, INFRARED SPECTROSCOPY, X RAY DIFFRACTION, CHEMICAL COMPOSITION, SUBSTITUTES, CHEMICAL ANALYSIS, ALKALI METAL COMPOUNDS.

  10. Axion crystals

    Science.gov (United States)

    Ozaki, Sho; Yamamoto, Naoki

    2017-08-01

    The low-energy effective theories for gapped insulators are classified by three parameters: permittivity ɛ, permeability μ, and theta angle θ. Crystals with periodic ɛ are known as photonic crystals. We here study the band structure of photons in a new type of crystals with periodic θ (modulo 2 π) in space, which we call the axion crystals. We find that the axion crystals have a number of new properties that the usual photonic crystals do not possess, such as the helicity-dependent mass gap and nonrelativistic gapless dispersion relation at small momentum. We briefly discuss possible realizations of axion crystals in condensed matter systems and high-energy physics.

  11. Calcium channel blocker overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used to ...

  12. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  13. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  14. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

  15. Growth and study of some gel grown group II single crystals of iodate

    Indian Academy of Sciences (India)

    Crystals having different morphologies and habits were obtained. Prismatic, dendritic crystals of barium iodate and prismatic, needle shaped, hopper crystals of calcium iodate were obtained. Some of them were transparent, some transluscent, and few others were opaque. Both the crystals were studied using XRD, FT-IR, ...

  16. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

    Directory of Open Access Journals (Sweden)

    Aminul Islam

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

  17. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

    Science.gov (United States)

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

    2015-01-01

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

  18. Spectroscopic study of erbium-activated crystals of double calcium yttrium fluoride Ca0.89Y0.11F2.11:Er3+: I. Intensity of spectra and luminescence kinetics

    Science.gov (United States)

    Tkachuk, A. M.; Ivanova, S. É.; Pellé, F.

    2009-06-01

    Ca0.89Y0.11F2.11:Er3+ (CYF:Er) crystals with an erbium content of 1-15 at % have been grown. The optical spectra and luminescence kinetics of CYF:Er crystals have been investigated at low (˜5 K) and room temperatures. Based on an analysis of the absorption spectra at low temperature, the structure of Stark splitting of erbium levels in CYF:Er crystals is determined. Room-temperature absorption spectra are used to calculate the spectra of absorption cross sections and oscillator strengths of transitions from the erbium ground state to excited multiplets. It is shown that the absorption spectrum of CYF:Er crystals contains broad bands in the ranges of 790-815 and 965-980 nm, which correspond to the range of emission of laser diodes. For the band peaking near 967 nm, the peak absorption cross section is σ{abs/max} = 2.7 × 10-21 cm2. The intensity parameters are determined by the Judd-Ofelt method to be Ω2 = 1.39 × 10-20, Ω4 = 1.34 × 10-20, and Ω6 = 2.24 × 10-20 cm2. The radiative transition probabilities, radiative lifetimes, and branching ratios are calculated with these values. The luminescence decay kinetics from excited erbium levels upon selective excitation is investigated and the experimental lifetimes of the 4 F 9/2, 4 S 3/2, and 4 G 11/2 radiative erbium levels are determined. The dependences of multiphonon relaxation rates on the energy gap in CYF:Er crystals are obtained. The rates of nonradiative multiphonon relaxation from radiative erbium levels are determined.

  19. First investigations on the quaternary system Na2O-K2O-CaO-SiO2: synthesis and crystal structure of the mixed alkali calcium silicate K1.08Na0.92Ca6Si4O15

    Science.gov (United States)

    Kahlenberg, Volker; Mayerl, Michael Jean-Philippe; Schmidmair, Daniela; Krüger, Hannes; Tribus, Martina

    2017-09-01

    In the course of an exploratory study on the quaternary system Na2O-K2O-CaO-SiO2 single crystals of the first anhydrous sodium potassium calcium silicate have been obtained from slow cooling of a melt in the range between 1250 and 1050 °C. Electron probe micro analysis suggested the following idealized molar ratios of the oxides for the novel compound: K2O:Na2O:CaO:SiO2 = 1:1:12:8 (or KNaCa6Si4O15). Single-crystal diffraction measurements on a crystal with chemical composition K1.08Na0.92Ca6Si4O15 resulted in the following basic crystallographic data: monoclinic symmetry, space group P 21/c, a = 8.9618(9) Å, b = 7.3594(6) Å, c = 11.2453(11) Å, β= 107.54(1)°, V = 707.2(1) Å3, Z = 2. Structure solution was performed using direct methods. The final least-squares refinement converged at a residual of R(|F|) = 0.0346 for 1288 independent reflections and 125 parameters. From a structural point of view, K1.08Na0.92Ca6Si4O15 belongs to the group of mixed-anion silicates containing [Si2O7]- and [SiO4]-units in the ratio 1:2. The mono- and divalent cations occupy a total of four crystallographically independent positions located in voids between the tetrahedra. Three of these sites are exclusively occupied by calcium. The fourth site is occupied by 54(1)% K and 46%(1) Na, respectively. Alternatively, the structure can be described as a heteropolyhedral framework based on corner-sharing silicate tetrahedra and [CaO6]-octahedra. The network can build up from kröhnkite-like [Ca(SiO4)2O2]-chains running along [001]. A detailed comparison with other A2B6Si4O15-compounds including topological and group-theoretical aspects is presented.

  20. Calcium pyrophosphate deposition disease: clinical manifestations

    Directory of Open Access Journals (Sweden)

    M.A. Cimmino

    2012-01-01

    Full Text Available Calcium pyrophosphate deposition (CPPD disease is an arthropathy caused by calcium pyrophosphate dihydrate (CPP crystal deposits in articular tissues, most commonly fibrocartilage and hyaline cartilage. According to EULAR, four different clinical presentations can be observed: 1 asymptomatic CPPD; 2 osteoarthritis (OA with CPPD; 3 acute CPP crystal arthritis; 4 chronic CPP inflammatory crystal arthritis. Acute CPP crystal arthritis is characterized by sudden onset of pain, swelling and tenderness with overlying erythema, usually in a large joint, most often the knee, wrist, shoulder, and hip. Occasionally, ligaments, tendons, bursae, bone and the spine can be involved. CPPD of the atlanto-occipital joint (crowned dens syndrome can cause periodic acute cervico-occipital pain with fever, neck stiffness and laboratory inflammatory syndrome. Chronic inflammatory arthritis is characterized by joint swelling, morning stiffness, pain, and high ESR and CRP. The relationship between OA and CPPD is still unclear. The main problem is whether such crystals are directly involved in the pathogenesis of OA or if they are the result of joint degeneration. Diagnosis is based on evaluation of history and clinical features, conventional radiology, and synovial fluid examination. Non-polarized light microscopy should be used initially to screen for CPPD crystals based upon their characteristic morphology, and compensated polarized light microscopy, showing the crystals to be weakly positive birefringent, is recommended for definitive identification, although this last pattern only occurs in about 20% of samples. The main goals of CPPD therapy are control of the acute or chronic inflammatory reaction and prevention of further episodes.

  1. Fabrications of zinc-releasing biocement combining zinc calcium phosphate to calcium phosphate cement.

    Science.gov (United States)

    Horiuchi, Shinya; Hiasa, Masahiro; Yasue, Akihiro; Sekine, Kazumitsu; Hamada, Kenichi; Asaoka, Kenzo; Tanaka, Eiji

    2014-01-01

    Recently, zinc-releasing bioceramics have been the focus of much attention owing to their bone-forming ability. Thus, some types of zinc-containing calcium phosphate (e.g., zinc-doped tricalcium phosphate and zinc-substituted hydroxyapatite) are examined and their osteoblastic cell responses determined. In this investigation, we studied the effects of zinc calcium phosphate (ZCP) derived from zinc phosphate incorporated into calcium phosphate cement (CPC) in terms of its setting reaction and MC3T3-E1 osteoblast-like cell responses. Compositional analysis by powder X-ray diffraction analysis revealed that HAP crystals were precipitated in the CPC containing 10 or 30wt% ZCP after successfully hardening. However, the crystal growth observed by scanning electron microscopy was delayed in the presence of additional ZCP. These findings indicate that the additional zinc inhibits crystal growth and the conversion of CPC to the HAP crystals. The proliferation of the cells and alkaline phosphatase (ALP) activity were enhanced when 10wt% ZCP was added to CPC. Taken together, ZCP added CPC at an appropriate fraction has a potent promotional effect on bone substitute biomaterials. © 2013 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Reddy, Michael M.; Hoch, Anthony

    2012-01-01

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

  3. Clonorcis sinensis eggs are associated with calcium carbonate gallbladder stones.

    Science.gov (United States)

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

    2014-10-01

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

  4. Investigation into crystallization of lithium-alumosilicate and calcium-magnesium-alumosilicate glasses by Cr/sup 3 +/, Cr/sup 5 +/ and V/sup 4 +/ ESR method

    Energy Technology Data Exchange (ETDEWEB)

    Abdrakhmanov, R.S.; Konoval, E.M.; Shishkin, I.V. (AN SSSR, Kazan. Fiziko-Tekhnicheskij Inst.)

    1983-01-01

    Investigation into structural peculiarities of glasses of Li/sub 2/O-Al/sub 2/O/sub 3/-SiO/sub 2/-ZnO-TiO/sub 2/-ZrO/sub 2/, Na/sub 2/O-CaO-MgO-Al/sub 2/O/sub 3/-SiO/sub 2/ and Na/sub 2/O-CaO-MgO-Al/sub 2/O/sub 3/-TiO/sub 2/-SiO/sub 2/ systems was conducted by Cr/sup 3 +/, Cr/sup 5 +/ and V/sup 4 +/ EPR method. The effect of small Cr/sub 2/O/sub 3/ and V/sub 2/O/sub 5/ additions on crystallization of these glasses was studied, the dislocation of magnetic ions in crystallized out glasses was revealed. Strengthening of structure character, realization of different types of Cr/sup 3 +/ complexes and intensification of disordered character of coordination spheres of vanadyl ion are observed in titanium containing glasses. Small additions of transition metal oxides effect noticeably on the character of formation of the basic and accompanying crystal phases, as well as on the dependence of temperature factor of linear expansion of glass ceramic of lithium aluminosilicate system on treatment temperature.

  5. Crystal rainbows

    Energy Technology Data Exchange (ETDEWEB)

    Neskovic, N. E-mail: nnesko@vin.bg.ac.yu; Petrovic, S

    2003-06-01

    This review is devoted to ion transmission through axial channels of thin crystals. In this process the rainbows occur. The effect is called the crystal rainbow effect. We shall describe its origin and present the experiments in which it has been observed. We shall explain also how the crystal rainbows can be classified using catastrophe theory. This classification has resulted in a universal, simple and accurate approximation to the continuum potential in the channels. Besides, the periodicity of the angular distributions of transmitted ions with the reduced crystal thickness will be considered. It will be introduced via the effect of zero-degree focusing of channeled ions. In addition, we shall mention the doughnut effect in ion channeling, which has proven to be the rainbow effect with tilted crystals. All these considerations will demonstrate clearly the usefulness of the theory of crystal rainbows, which is the proper theory of ion channeling in thin crystals00.

  6. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  7. Crystal structure of sucrose phosphorylase from Bifidobacterium adolescentis

    DEFF Research Database (Denmark)

    Sprogøe, Desiree; van den Broek, Lambertus A M; Mirza, Osman

    2004-01-01

    ', and C. Domain A comprises the (beta/alpha)(8)-barrel common to family 13. The catalytic active-site residues (Asp192 and Glu232) are located at the tips of beta-sheets 4 and 5 in the (beta/alpha)(8)-barrel, as required for family 13 members. The topology of the B' domain disfavors oligosaccharide......Around 80 enzymes are implicated in the generic starch and sucrose pathways. One of these enzymes is sucrose phosphorylase, which reversibly catalyzes the conversion of sucrose and orthophosphate to d-Fructose and alpha-d-glucose 1-phosphate. Here, we present the crystal structure of sucrose...... binding and reduces the size of the substrate access channel compared to other family 13 members, underlining the role of this domain in modulating the function of these enzymes. It is remarkable that the fold of the C domain is not observed in any other known hydrolases of family 13. BiSP was found...

  8. Calcium and calcium magnesium carbonate specimens submitted as urinary tract stones.

    Science.gov (United States)

    Gault, M H; Chafe, L; Longerich, L; Mason, R A

    1993-02-01

    Of 8,129 specimens submitted as urinary stones from 6,095 patients, 67 from 15 patients were predominantly calcium carbonate or calcium magnesium carbonate (dolomite) by infrared analysis. Detailed study of 1 man and 4 women who submitted 3 or more such specimens showed that all were of aragonite calcium carbonate crystal form in 2 women and all calcite in the man. All 3 patients had a long history of nephrolithiasis preceding submission of calcium carbonate stones. There was frequent and often painful spontaneous passage of many small stones. Medullary sponge kidney was reported in 2 patients. Specimens submitted by the other 2 women included dolomite and quartz artifacts. Of the other 10 patients 4 had calcite and 1 had aragonite (possibly true stones). Five patients had artifacts with dolomite in 3 and mixed specimens in 2. True calcium carbonate kidney stones and calcium carbonate artifacts may be difficult to distinguish, and dolomite and quartz artifacts may require x-ray diffraction for clear-cut diagnosis.

  9. Protein Crystallization

    Science.gov (United States)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  10. Calcium carbonate precipitation in the Cueva di Watapana on Bonaire, Netherlands Antilles

    NARCIS (Netherlands)

    Meer Mohr, van der C.G.

    1978-01-01

    Calcium carbonate precipitates as low Mg-calcite and aragonite in slightly brackish water in a cave in the Pleistocene Middle Terrace of southern Bonaire. The calcium carbonate precipitates at the atmosphere-water interface forming floating calcite scales (calcite ice). Aragonite crystals frequently

  11. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

  12. Computational crystallization.

    Science.gov (United States)

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Calcium and bones

    Science.gov (United States)

    ... eat in their diet. Vitamin D is the hormone that helps the gut absorb more calcium. Many older adults have common risks that make bone health worse. Calcium intake in the diet (milk, cheese, yogurt) is low. Vitamin D levels are ...

  14. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  15. Extracellular Calcium and Magnesium

    African Journals Online (AJOL)

    ABSTRACT. The cause of preeclampsia remains unknown and calcium and magnesium supplement are being suggested as means of prevention. The objective of this study was to assess magnesium and calcium in the plasma and cerebrospinal fluid of Nigerian women with preedamp sia and eclampsia. Setting was ...

  16. Crystals in brain and meninges in primary hyperoxaluria and oxalosis.

    Science.gov (United States)

    Haqqani, M T

    1977-01-01

    A case of primary hyperoxaluria and oxalosis with chronic renal failure, crystalline myocarditis, and disseminated calcium oxalate crystal deposition in various tissues including the brain and meninges is described. Deposition of crystals in brain and meninges is exceptionally rare in primary oxalosis. Images PMID:838867

  17. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free

  18. Factors influencing the crystallisation of calcium oxalate in urine - critique

    Science.gov (United States)

    Robertson, W. G.; Scurr, D. S.; Bridge, Christine M.

    1981-05-01

    This article describes in vivo and in vitro studies carried out to determine the factors which influence the nucleation, crystal growth and crystal aggregation of calcium oxalate in urine. It covers the roles of urinary supersaturation, the oxalate/calcium ratio of urine, the relative importance of hyperoxaluria and hypercalciuria in causing crystalluria and the importance of crystalluria in the genesis of calcium oxalate stones. In vitro studies on seeded crystal growth and aggregation and on the spontaneous precipitation of calcium oxalate define some of the macromolecular factors in urine which promote and inhibit crystal growth and aggregation. Fractionation of the urinary macromolecular anions shows that the major inhibitors are in the acidic glycosaminoglycan fraction with relatively minor contributions from Tamm-Horsfall mucoprotein and from RNA. One insoluble residue acts as a weak promoter of growth and aggregation but when re-combined with the inhibitory fractions the promoter effect is cancelled out. The net effect of urine is to inhibit strongly growth and aggregation.

  19. Shape control synthesis of low-dimensional calcium sulfate

    Indian Academy of Sciences (India)

    Calcium sulfate nanorods, nanowires, nanobelts and sheets had been synthesized via a facile solution reaction of CaCl2 and H2SO4 in mixed solvents of ethanol/, -dimethylformamide and deionized water at 35°C. The results indicated that well-crystallized CaSO4 nanomaterials with different morphology were obtained ...

  20. Calcium Carbonate Nucleation Investigated in a Double Pulse Experiment

    NARCIS (Netherlands)

    Liszka, B.; Wagterveld, R.M.; Witkamp, G.J.; Otto, Cornelis

    2016-01-01

    The nucleation rate is essential in a number of research fields in order to control crystal formation. The purpose of this study is to test and optimize the double pulse procedure as a method to investigate nucleation of calcium carbonate. The induction time, interpreted as time of formation of

  1. Fractionation behavior of chromium isotopes during coprecipitation with calcium carbonate

    DEFF Research Database (Denmark)

    Rodler, Alexandra; Sánchez-Pastor, Nuria; Fernández-Díaz, Lurdes

    2015-01-01

    Interest in chromium (Cr) isotope incorporation into carbonates arises from the observation that Cr isotopic composition of carbonates could be used as a paleoclimate proxy to elucidate past fluctuations of oxygen contents in atmosphere and hydrosphere. The use of Cr isotopes to track....... The fractionation of Cr isotopes during calcium carbonate coprecipitation was assumed to be small, based on previously published data of modern seawater and modern non-skeletal marine carbonates. However, results from this study for rapidly precipitated calcium carbonate in the presence of chromate show a tendency...... showed the presence of vaterite. Calcium carbonate crystals were also precipitated in a double diffusion silica hydrogel over a longer period of time resulting in samples consisting of micrometric-millimetric calcite crystals, which were again significantly enriched in heavy Cr isotopes compared...

  2. Calcium sensing in exocytosis

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

    2012-01-01

    Neurotransmitters, neuropeptides and hormones are released through regulated exocytosis of synaptic vesicles and large dense core vesicles. This complex and highly regulated process is orchestrated by SNAREs and their associated proteins. The triggering signal for regulated exocytosis is usually...... an increase in intracellular calcium levels. Besides the triggering role, calcium signaling modulates the precise amount and kinetics of vesicle release. Thus, it is a central question to understand the molecular machineries responsible for calcium sensing in exocytosis. Here we provide an overview of our...

  3. Glass forming ability of calcium aluminosilicate melts

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Yue, Yuanzheng

    2011-01-01

    The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite-wollastonite-tridymite and that of......The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite......-wollastonite-tridymite and that of anorthite-wollastonite-gehlenite. The series includes the eutectic compositions as end members. The second series consists of five compositions on a line parallel to the joining line on the alumina rich side. In the present work, GFA is described in terms of glass stability, i.e., the ability of a glass...... to resist crystallization during reheating. In addition, the fragility index (m) is derived by fitting the viscosity data with the Avramov-Milchev equation. The results show that m is inversely proportional to the glass stability for the two series of melts, implying that m is an indirect measure of GFA...

  4. Effect of thermal annealing on the microstructures and photocatalytic performance of silver orthophosphate: The synergistic mechanism of Ag vacancies and metallic Ag

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Tingjiang, E-mail: tingjiangn@163.com [The Key Laboratory of Life-Organic Analysis, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Guan, Wenfei; Xiao, Ying; Tian, Jun; Qiao, Zheng; Zhai, Huishan; Li, Wenjuan; You, Jinmao [The Key Laboratory of Life-Organic Analysis, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165 (China)

    2017-01-01

    Highlights: • Ag{sub 3}PO{sub 4} was initially prepared via ion-exchange reaction and then annealed in air. • Thermal annealing also resulted in the formation of metallic Ag and Ag vacancies. • The annealed samples exhibited superior activity to the pristine sample. • Both Ag vacancies and metallic Ag contributed to the high activity. - Abstract: In this work, a simple thermal annealing route has been developed to improve the photocatalytic performance of silver orthophosphate (Ag{sub 3}PO{sub 4}) photocatalyst toward organic pollutants degradation under visible light irradiation. The experimental results indicated that thermal treatment of Ag{sub 3}PO{sub 4} led to an obvious lattice shift towards right and significantly narrowed band gap energies due to the formation of Ag vacancies and metallic Ag during Ag{sub 3}PO{sub 4} decomposition. These structural variations notably affected the photocatalytic performance of Ag{sub 3}PO{sub 4} photocatalysts. The activity of the annealed samples was found to be significantly enhanced toward the degradation of MO dye. The highest activity was observed over the sample annealed at 400 °C, which exceeded that of pristine Ag{sub 3}PO{sub 4} by a factor of about 21 times. By means of photoluminescence spectroscopy and photoelectrochemical measurements, we propose that the enormous enhancement in activity was mainly attributed to the efficient separation of photogenerated electrons and holes driven by the synergistic effect of Ag vacancies and metallic Ag. The strong interaction between annealed particles also inhibited the dissolution of Ag{sup +} from Ag{sub 3}PO{sub 4} into aqueous solution, contributing to an improved photocatalytic stability. The strategy presented here provides an ideal platform for the design of other highly efficient and stable Ag-based photocatalysts for broad applications in the field of photocatalysis.

  5. Synthesis and thermic behaviour (stability and sintering) of rare earth ortho-phosphates; Synthese et comportement thermique (stabilite et frittage) de phosphates de terres rares ceriques ou yttriques

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, S

    2003-04-01

    Rare earth ortho-phosphates, LnPO{sub 4},nH{sub 2}O (Ln = La, Ce or Y), were synthesized by precipitation in aqueous media. The effect of pH, temperature, reagents stoichiometry and ripening time on the chemical composition and the morphology of the precipitates have been precised. The study of the thermal behaviour showed the presence of meta-phosphates as a secondary phase in the temperature range 1000 C - 1400 C that was very detrimental to the sintering. It is removed by calcining the powders at 1400 C. Thermogravimetry proved to be the best technique in order to insure the purity of the precipitates since it allows the detection of this phase down to a lower threshold than that associated with the other investigated characterization methods (IR or Raman spectrometry, chemical analysis, XRD, DTA). The monazites (La or Ce)PO{sub 4} densify at 1400 C by natural sintering whereas the xenotime YPO{sub 4} is not yet densified at 1500 C. Hot pressing at that temperature is required to its densification. The mechanical properties of the monazites remain low (sf about 120 MPa, K{sub IC} about 1.2 MPa.m{sup 1/2}). The xenotime ceramic is much more mechanically resistant (sf about 320 MPa, K{sub IC} about 1.5 MPa.m{sup 1/2}). An important acicular growth of the grains during the sintering of the xenotime (that occurs also during the synthesis process) is considered to be responsible for the behaviour and properties differences between this material and monazites. (author)

  6. Particle Size, Surface Area, and Amorphous Content as Predictors of Solubility and Bioavailability for Five Commercial Sources of Ferric Orthophosphate in Ready-To-Eat Cereal

    Directory of Open Access Journals (Sweden)

    Robin S. Dickmann

    2016-03-01

    Full Text Available Ferric orthophosphate (FePO4 has had limited use as an iron fortificant in ready-to-eat (RTE cereal because of its variable bioavailability, the mechanism of which is poorly understood. Even though FePO4 has desirable sensory properties as compared to other affordable iron fortificants, few published studies have well-characterized its physicochemical properties. Semi-crystalline materials such as FePO4 have varying degrees of molecular disorder, referred to as amorphous content, which is hypothesized to be an important factor in bioavailability. The objective of this study was to systematically measure the physicochemical factors of particle size, surface area, amorphous content, and solubility underlying the variation in FePO4 bioavailability. Five commercial FePO4 sources and ferrous sulfate were added to individual batches of RTE cereal. The relative bioavailability value (RBV of each iron source, determined using the AOAC Rat Hemoglobin Repletion Bioassay, ranged from 51% to 99% (p < 0.05, which is higher than typically reported. Solubility in dilute HCl accurately predicted RBV (R2 = 0.93, p = 0.008. Amorphous content measured by Dynamic Vapor Sorption ranged from 1.7% to 23.8% and was a better determinant of solubility (R2 = 0.91; p = 0.0002 than surface area (R2 = 0.83; p = 0.002 and median particle size (R2 = 0.59; p = 0.12. The results indicate that while solubility of FePO4 is highly predictive of RBV, solubility, in turn, is strongly linked to amorphous content and surface area. This information may prove useful for the production of FePO4 with the desired RBV.

  7. Bone repair in calcium-deficient rats: comparison of xylitol+calcium carbonate with calcium carbonate, calcium lactate and calcium citrate on the repletion of calcium.

    Science.gov (United States)

    Hämäläinen, M M

    1994-06-01

    The potential value of xylitol in calcium therapy was evaluated by comparing the effect of dietary xylitol (50 g/kg diet) + calcium carbonate with the effects of calcium carbonate, calcium lactate and calcium citrate on bone repair of young male rats after the rats consumed for 3 wk a calcium-deficient diet (0.2 g Ca/kg diet). After this calcium-depletion period, the rats were fed for 2 wk one of four diets, each containing 5 g Ca/kg diet as one of the four dietary calcium sources. The diet of the control animals was supplemented with CaCO3 (5 g Ca/kg diet) throughout the study. The Ca-deficient rats showed low bone mass, low serum calcium and high serum 1,25-dihydroxycholecalciferol, parathyroid hormone (1-34 fraction) and osteocalcin concentrations. They also excreted magnesium, phosphate and hydroxyproline in the urine in high concentrations, and had high bone alkaline phosphatase and tartrate-resistant acid phosphatase activities. Most of these changes were reversed by the administered of the calcium salts. The highest recoveries of femoral dry weight, calcium, magnesium and phosphate were observed in the groups receiving xylitol+CaCO3 and calcium lactate. Calcium lactate and calcium citrate caused low serum phosphate concentration compared with rats receiving CaCO3 and with the age-matched Ca-replete controls. Xylitol-treated rats excreted more calcium and magnesium in urine than did the other rats, probably due to increased absorption of these minerals from the gut. These results suggest that dietary xylitol improves the bioavailability of calcium salts.

  8. Study of calcium carbonate and sulfate co-precipitation

    KAUST Repository

    Zarga, Y.

    2013-06-01

    Co-precipitation of mineral based salts in scaling is still not well understood and/or thermodynamically well defined in the water industry. This study focuses on investigating calcium carbonate (CaCO3) and sulfate mixed precipitation in scaling which is commonly observed in industrial water treatment processes including seawater desalination either by thermal-based or membrane-based processes. Co-precipitation kinetics were studied carefully by monitoring several parameters simultaneously measured, including: pH, calcium and alkalinity concentrations as well as quartz microbalance responses. The CaCO3 germination in mixed precipitation was found to be different than that of simple precipitation. Indeed, the co-precipitation of CaCO3 germination time was not anymore related to supersaturation as in a simple homogenous precipitation, but was significantly reduced when the gypsum crystals appeared first. On the other hand, the calcium sulfate crystals appear to reduce the energetic barrier of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic Microscopy (SEM) were used to identify the nature of scales structures. Gypsum was found to be the dominant precipitate while calcite and especially vaterite were found at lower proportions. These analyses showed also that gypsum crystals promote calcite crystallization to the detriment of other forms. © 2013 Elsevier Ltd.

  9. Crystal Dislocations

    Directory of Open Access Journals (Sweden)

    Ronald W. Armstrong

    2016-01-01

    Full Text Available Crystal dislocations were invisible until the mid-20th century although their presence had been inferred; the atomic and molecular scale dimensions had prevented earlier discovery. Now they are normally known to be just about everywhere, for example, in the softest molecularly-bonded crystals as well as within the hardest covalently-bonded diamonds. The advent of advanced techniques of atomic-scale probing has facilitated modern observations of dislocations in every crystal structure-type, particularly by X-ray diffraction topography and transmission electron microscopy. The present Special Issue provides a flavor of their ubiquitous presences, their characterizations and, especially, their influence on mechanical and electrical properties.

  10. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears ...

  11. Microbial phytase-induced calcium-phosphate precipitation : A potential soil stabilization method

    NARCIS (Netherlands)

    Roeselers, G.; Van Loosdrecht, M.C.M.

    2011-01-01

    Two hypotheses were tested: (1) microbial dephosphorylation of phytate in the presence of Ca2+ ions will result in the precipitation of hydroxyapatite-like crystals and (2) precipitation of calcium-phosphate crystals on and between sand-like particles can cause cementation. A growing culture of the

  12. Calcium and Your Child

    Science.gov (United States)

    ... Milk Allergy Figuring Out Food Labels What's a Vegetarian? Osteoporosis Minerals Your Bones Mineral Chart Vitamin D ... Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium Bones, Muscles, and ...

  13. Stoichiometry of Calcium Medicines

    Science.gov (United States)

    Pinto, Gabriel

    2005-01-01

    The topic of calcium supplement and its effects on human lives is presented in the way of questions to the students. It enables the students to realize the relevance of chemistry outside the classroom surrounding.

  14. Magnesium, calcium and cancer

    National Research Council Canada - National Science Library

    Anghileri, Leopoldo J

    2009-01-01

    Magnesium ion (Mg(2+)) and calcium ion (Ca(2+)) control a diverse and important range of cellular processes, such as gene transcription, cell proliferation, neoplastic transformation, immune response and therapeutic treatment...

  15. Liquid crystal tunable photonic crystal dye laser

    DEFF Research Database (Denmark)

    Buss, Thomas; Christiansen, Mads Brøkner; Smith, Cameron

    2010-01-01

    We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium.......We present a dye-doped liquid crystal laser using a photonic crystal cavity. An applied electric field to the liquid crystal provides wavelength tunability. The photonic crystal enhances resonant interaction with the gain medium....

  16. Hexahedrally based crystals in human tooth enamel.

    Science.gov (United States)

    Kodaka, T; Debari, K; Abe, M

    1992-01-01

    Mg-containing calcium phosphate crystals including pseudocuboidal, rhombohedral shapes and groupings of quadrangular blades cubically arranged were found in human tooth enamel by scanning electron microscopy and by electron probe microanalysis. In caries-free old enamel, these hexahedrally based crystals measuring 0.5-2.5 microns in length were observed in some crevices of tufts and lamellae. The crystals were rarely seen in the inner crevices of caries-free exfoliated deciduous enamel and none could be seen in sound young enamel. In brown-coloured old enamel possessing arrested caries with lamellae, some of the lamellae contained crystals measuring 0.1-1.5 mu in length adjacent to half-dissolved prisms. These crystals, identified as Mg-containing whitlockite, will grow during a long period after eruption of the tooth or during the enamel caries process.

  17. Production and basic morphology of struvite crystals from a pilot-scale crystallization process.

    Science.gov (United States)

    Huang, H; Mavinic, D S; Lo, K V; Koch, F A

    2006-03-01

    A pilot-scale, struvite crystallization process was operated using anaerobic digester supernatants from two, full-scale, treatment plants as influent. It was found that the produced struvite crystals were easily separated from the process and were composed of very pure struvite (91.2 % to 94.1 % purity), with small amounts of calcium and carbonate, and traces of iron and aluminum. Most of the harvested struvite crystals, which were an aggregation of numerous fine crystals, were round, hard and larger than 1.5 mm in mean diameter. The crystal retention time in the reactor and the magnesium dosage in the supernatant appeared to have a significant effect on the crystal size, hardness and morphology.

  18. Application of pyrolitic method of synthesis for preparation of calcium bismuthate based photocatalyst

    Science.gov (United States)

    Shtarev, Dmitry S.; Makarevich, Konstantin S.; Shtareva, Anna V.; Blokh, Artem I.; Syuy, Alexander V.

    2016-11-01

    The study describes use of pyrolytic synthesis method for preparation of visible light calcium bismuthate based photocatalyst. The advantage of the proposed method is that it allows obtaining single-phase, homogeneous samples with various types of crystal lattice and controlled defects. It is shown that it is possible to obtain crystalline calcium bismuthate with the same stoichiometry in the entire region of existence of the solid solution. Synthesized samples of calcium bismuthate have been characterized using the scanning electron microscopy and X-ray analysis. It was found that the scope and conditions of synthesis affect the degree of imperfection of both anionic and cationic sublattice of calcium bismuthate.

  19. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

  20. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  1. Effects of functional groups and soluble matrices in fish otolith on calcium carbonate mineralization.

    Science.gov (United States)

    Ren, Dongni; Li, Zhuo; Gao, Yonghua; Feng, Qingling

    2010-10-01

    Calcium carbonate mineralization is significantly influenced by organic matrices in vivo. The effect mainly relies on functional groups in proteins. In order to study the influence of functional groups on calcium carbonate mineralization, -OH, -NH2 and -COOH groups were grafted onto single crystal silicon chips, and such modified chips were used as substrates in in vitro mineralization experiments. An x-ray photoelectron spectroscopy (XPS) test was conducted to examine the grafting efficiency, and the three groups were successfully grafted. Calcium carbonate mineralization on a modified silicon substrate was examined by a scanning electron microscope (SEM) and x-ray diffraction (XRD), and the results showed that the effects of -OH, -NH2 and -COOH groups were quite different. Furthermore, a water-soluble protein matrix (WSM) and an acid-soluble protein matrix (ASM) extracted from fish otolith were adsorbed onto the -COOH-modified silicon substrate, and the effects of the protein matrices on calcium carbonate mineralization were studied. The results showed that both WSM and ASM of lapillus could mediate aragonite crystallization, but the size and morphology of the formed crystals were different. The WSM and ASM of asteriscus adsorbed on the silicon substrate had little effect on calcium carbonate mineralization; almost all the crystals were calcite, while both asteriscus WSM and ASM in solution could mediate vaterite crystals, and the morphologies of vaterite crystal aggregates were different.

  2. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  3. Contribution of calcium oxalate to soil-exchangeable calcium

    Science.gov (United States)

    Dauer, Jenny M.; Perakis, Steven S.

    2013-01-01

    Acid deposition and repeated biomass harvest have decreased soil calcium (Ca) availability in many temperate forests worldwide, yet existing methods for assessing available soil Ca do not fully characterize soil Ca forms. To account for discrepancies in ecosystem Ca budgets, it has been hypothesized that the highly insoluble biomineral Ca oxalate might represent an additional soil Ca pool that is not detected in standard measures of soil-exchangeable Ca. We asked whether several standard method extractants for soil-exchangeable Ca could also access Ca held in Ca oxalate crystals using spike recovery tests in both pure solutions and soil extractions. In solutions of the extractants ammonium chloride, ammonium acetate, and barium chloride, we observed 2% to 104% dissolution of Ca oxalate crystals, with dissolution increasing with both solution molarity and ionic potential of cation extractant. In spike recovery tests using a low-Ca soil, we estimate that 1 M ammonium acetate extraction dissolved sufficient Ca oxalate to contribute an additional 52% to standard measurements of soil-exchangeable Ca. However, in a high-Ca soil, the amount of Ca oxalate spike that would dissolve in 1 M ammonium acetate extraction was difficult to detect against the large pool of exchangeable Ca. We conclude that Ca oxalate can contribute substantially to standard estimates of soil-exchangeable Ca in acid forest soils with low soil-exchangeable Ca. Consequently, measures of exchangeable Ca are unlikely to fully resolve discrepancies in ecosystem Ca mass balance unless the contribution of Ca oxalate to exchangeable Ca is also assessed.

  4. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  5. Mineral deposition in bacteria-filled and bacteria-free calcium bodies in the crustacean Hyloniscus riparius (Isopoda: Oniscidea.

    Directory of Open Access Journals (Sweden)

    Miloš Vittori

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

  6. Osseoconductive and Corrosion-Inhibiting Plasma-Sprayed Calcium Phosphate Coatings for Metallic Medical Implants

    Directory of Open Access Journals (Sweden)

    Robert B. Heimann

    2017-11-01

    Full Text Available During the last several decades, research into bioceramic coatings for medical implants has emerged as a hot topic among materials scientists and clinical practitioners alike. In particular, today, calcium phosphate-based bioceramic materials are ubiquitously used in clinical applications to coat the stems of metallic endoprosthetic hips as well as the surfaces of dental root implants. Such implants frequently consist of titanium alloys, CoCrMo alloy, or austenitic surgical stainless steels, and aim at replacing lost body parts or restoring functions to diseased or damaged tissues of the human body. In addition, besides such inherently corrosion-resistant metals, increasingly, biodegradable metals such as magnesium alloys are being researched for osseosynthetic devices and coronary stents both of which are intended to remain in the human body for only a short time. Biocompatible coatings provide not only vital biological functions by supporting osseoconductivity but may serve also to protect the metallic parts of implants from corrosion in the aggressive metabolic environment. Moreover, the essential properties of hydroxylapatite-based bioceramic coatings including their in vitro alteration in contact with simulated body fluids will be addressed in this current review paper. In addition, a paradigmatic shift is suggested towards the development of transition metal-substituted calcium hexa-orthophosphates with the NaSiCON (Na superionic conductor structure to be used for implant coatings with superior degradation resistance in the corrosive body environment and with pronounced ionic conductivity that might be utilized in novel devices for electrical bone growth stimulation.

  7. Defective urinary crystallization inhibition and urinary stone formation

    Directory of Open Access Journals (Sweden)

    Mauricio Carvalho

    2006-06-01

    Full Text Available INTRODUCTION: Nephrocalcin (NC is a glycoprotein produced in the kidney and inhibits calcium oxalate crystal formation. It has been separated into 4 isoforms (A, B, C, and D and found that (A + B are more abundant than (C + D in urine of healthy subjects, but the reverse is seen in human urine of kidney stone patients. To further examine the role of this protein in inhibition of urinary crystallization, nephrocalcin isoforms were purified from 2 genetically pure dog species. MATERIALS AND METHODS: We studied healthy Beagles, known to be non-stone forming dogs, and Mini-Schnauzers, known to be calcium oxalate stone formers. NC was isolated and purified from each group. Urinary biochemistry and calcium oxalate crystal growth inhibition were measured. RESULTS: Specific crystal growth inhibition activity was significantly higher in non-stone forming dogs (9.79 ± 2.25 in Beagles vs. 2.75 ± 1.34 of Mini-Schnauzers, p < 0.005. Dissociation constants toward calcium oxalate monohydrate were 10-fold different, with Beagles' isoforms being 10 times stronger inhibitors compare to those of Mini-Schnauzers'. Isoforms C + D of NC were the main isoforms isolated in stone-forming dogs. CONCLUSION: NC of these two species of dogs differently affects calcium oxalate crystallization and might have a role in determining ulterior urinary stone formation.

  8. Urine risk factors in children with calcium kidney stones and their siblings.

    Science.gov (United States)

    Bergsland, Kristin J; Coe, Fredric L; White, Mark D; Erhard, Michael J; DeFoor, William R; Mahan, John D; Schwaderer, Andrew L; Asplin, John R

    2012-06-01

    Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence, treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone-forming children, we compared chemical measurements and the crystallization properties of 24-h urine collections from 129 stone formers matched to 105 non-stone-forming siblings and 183 normal, healthy children with no family history of stones, all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH, and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

  9. The initial and subsequent inflammatory events during calcium oxalate lithiasis.

    Science.gov (United States)

    Yuen, John W M; Gohel, Mayur-Danny I; Poon, Ngork-Wah; Shum, Daisy K Y; Tam, Po-Chor; Au, Doris W T

    2010-08-05

    Crystallization is believed to be the initiation step of urolithiasis, even though it is unknown where inside the nephron the first crystal nucleation occurs. Direct nucleation of calcium oxalate and subsequent events including crystal retention, cellular damage, endocytosis, and hyaluronan (HA) expression, were tested in a two-compartment culture system with intact human proximal tubular HK-2 cell monolayer. Calcium oxalate dihydrate (COD) was nucleated and bound onto the apical surface of the HK-2 cells under hypercalciuric and hyperoxaluric conditions. These cells displayed mild cellular damage and internalized some of the adhered crystals within 18h post-COD-exposure, as revealed by electron microscopy. Prolonged incubation in complete medium caused significant damage to disrupt the monolayer integrity. Furthermore, hyaluronan disaccharides were detected in the harvested media, and were associated with HAS-3 mRNA expression. Human proximal cells were able to internalize COD crystals which nucleated directly onto the apical surface, subsequently triggering cellular damage and HAS-3 specific hyaluronan synthesis as an inflammatory response. The proximal tubule cells here demonstrate that it plays an important role in facilitating urolithiasis via endocytosis and creating an inflammatory environment whereby free hyaluronan in tubular fluid can act as crystal-binding molecule at the later segments of distal and collecting tubules. Copyright 2010 Elsevier B.V. All rights reserved.

  10. Liquid Crystals

    Science.gov (United States)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  11. Phosphoenolpyruvate carboxykinase, pyruvate orthophosphate dikinase and isocitrate lyase in both tomato fruits and leaves, and in the flesh of peach and some other fruits.

    Science.gov (United States)

    Famiani, Franco; Paoletti, Andrea; Battistelli, Alberto; Moscatello, Stefano; Chen, Zhi-Hui; Leegood, Richard C; Walker, Robert P

    2016-09-01

    In this study the occurrence of a number of enzymes involved in gluconeogenesis was investigated in both tomato fruits and leaves during their development and senescence and in some other fruits. The enzymes studied were phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK) and glyoxysomal isocitrate lyase (ICL). PPDK was detected in the ripe flesh of tomato, and much smaller amounts were detected in the flesh of both peach and pepper, whereas it was not detected (not present or at very low abundance) in the other fruits which were investigated (apricot, aubergine, blackberry, blueberry, cherry, grape, plum, raspberry and red current). By contrast PEPCK was present in the flesh of all the fruits investigated. Very small amounts of ICL were detected in ripe tomato flesh. PEPCK was present in the skin, flesh, locular gel and columella of tomato fruit, and in these its abundance increased greatly during ripening. PPDK showed a similar distribution, however, its abundance did not increase during ripening. PEPCK was not detected in tomato leaves at any stage of their development or senescence. The content of PPDK g(-1) fresh weight (FW) increased in tomato leaves as they matured, however, it declined during their senescence. In tomato leaves the content of ICL g(-1) FW increased until the mid-stage of development, then decreased as the leaf matured, and then increased during the latter stages of senescence. In the flesh of tomato fruits the contents of PPDK and PEPCK g(-1) FW decreased during senescence. The results suggest that in fruits other than tomato the bulk of any gluconeogenic flux proceeds via PEPCK, whereas in tomato both PEPCK and PPDK could potentially be utilised. Further, the results indicate that the conversion of pyruvate/acetyl-CoA to malate by the glyoxylate cycle, for which ICL is necessary, is not a major pathway utilised by gluconeogenesis in fruits under normal conditions of growth. Finally, the results contribute to

  12. Calcium carbonate crystallisation at the microscopic level

    CERN Document Server

    Dobson, P S

    2001-01-01

    The primary concern of this thesis is the investigation of crystal nucleation and growth processes, and the effect of foreign substrates on the rate, extent and mechanism of crystallisation, with particular emphasis on the calcium carbonate system. A methodology, based on the in-line mixing of two stable solutions, which permits the continuous delivery of a solution with a constant, known supersaturation, has been developed and characterised. This has been used to induce CaCO sub 3 crystallisation in experimental systems involving the channel flow and wall jet techniques. The channel flow method has been adapted to facilitate the study of crystal growth at a single calcite crystal. Ca sup 2 sup + ion selective electrodes have been employed as a means of monitoring depletion of the supersaturated solution, downstream of the crystal substrate. The data obtained suggested a growth rate constant of 3x10 sup - sup 1 sup 2 mol cm sup - sup 2 s sup - sup 1 (and a reaction order of 1.52 on supersaturation). The ex-si...

  13. The Formation Process of Silico-Ferrite of Calcium (SFC) from Binary Calcium Ferrite

    Science.gov (United States)

    Ding, Xiang; Guo, Xing-Min

    2014-08-01

    Silico-ferrite of calcium (SFC) is a significant equilibrium crystalline phase in the Fe2O3-CaO-SiO2 (FCS) ternary system and a key bonding phase in the sintering process of fine iron ore. In this work, the formation process of SFC from binary calcium ferrite has been determined by X-ray diffraction and field-emission scanning electron microscopy. Experiments were carried out under air at 1473 K (1200 °C) by adding SiO2 and Fe2O3 into CaO·Fe2O3 (CF). It was found that the formation of SFC is dominated by solid-state reactions in the FCS ternary system, in which Fe2O3 reacts with CaO·Fe2O3 to form the binary calcium ferrite phase. The chemical composition of binary calcium ferrite is Ca2.5Fe15.5O25 and approximately Ca2Fe12O20 (CaO·3Fe2O3). Then Si4+ and Ca2+ ions take the place of Fe3+ ion in preference located on the octahedral layers which belongs to (0 0 18) plane of binary calcium ferrite. The crystal structure of binary calcium ferrite gradually transforms from orthorhombic to triclinic, and the grain is refined with the addition of silica due to the smaller radius of Si4+ ion. A solid solution SFC forms completely when the content of SiO2 reaches approximately 3.37 wt pct at 1473 K (1200 °C).

  14. Calcium Signalling: Fishing Out Molecules of Mitochondrial Calcium Transport

    OpenAIRE

    Hajnóczky, György; Csordás, György

    2010-01-01

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins — MICU1, NCLX and LETM1 — to the previously unknown molecular mechanism of mitochondrial calcium transport.

  15. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    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)

  16. Molecular modifiers reveal a mechanism of pathological crystal growth inhibition

    Science.gov (United States)

    Chung, Jihae; Granja, Ignacio; Taylor, Michael G.; Mpourmpakis, Giannis; Asplin, John R.; Rimer, Jeffrey D.

    2016-08-01

    Crystalline materials are crucial to the function of living organisms, in the shells of molluscs, the matrix of bone, the teeth of sea urchins, and the exoskeletons of coccoliths. However, pathological biomineralization can be an undesirable crystallization process associated with human diseases. The crystal growth of biogenic, natural and synthetic materials may be regulated by the action of modifiers, most commonly inhibitors, which range from small ions and molecules to large macromolecules. Inhibitors adsorb on crystal surfaces and impede the addition of solute, thereby reducing the rate of growth. Complex inhibitor-crystal interactions in biomineralization are often not well elucidated. Here we show that two molecular inhibitors of calcium oxalate monohydrate crystallization—citrate and hydroxycitrate—exhibit a mechanism that differs from classical theory in that inhibitor adsorption on crystal surfaces induces dissolution of the crystal under specific conditions rather than a reduced rate of crystal growth. This phenomenon occurs even in supersaturated solutions where inhibitor concentration is three orders of magnitude less than that of the solute. The results of bulk crystallization, in situ atomic force microscopy, and density functional theory studies are qualitatively consistent with a hypothesis that inhibitor-crystal interactions impart localized strain to the crystal lattice and that oxalate and calcium ions are released into solution to alleviate this strain. Calcium oxalate monohydrate is the principal component of human kidney stones and citrate is an often-used therapy, but hydroxycitrate is not. For hydroxycitrate to function as a kidney stone treatment, it must be excreted in urine. We report that hydroxycitrate ingested by non-stone-forming humans at an often-recommended dose leads to substantial urinary excretion. In vitro assays using human urine reveal that the molecular modifier hydroxycitrate is as effective an inhibitor of nucleation

  17. Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

    Directory of Open Access Journals (Sweden)

    Rajan Choudhary

    2015-06-01

    Full Text Available The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7 using eggshell biowaste (as calcium source, magnesium nitrate and tetraethyl orthosilicate (TEOS as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesium silicate was carried out by powder X-ray diffraction (XRD, Fourier transform infrared (FTIR and scanning electron microscopy (SEM techniques. Calcium magnesium silicate crystallite size was observed in nano regime which can effectively mimic natural bone apatite composition. In-vitro bioactivity was investigated by immersing calcium magnesium silicate pellet in simulated body fluid (SBF for three weeks. Results show effective deposition of crystallized hydroxyapatite (HAP layer on its surface and predicting its possibilities for applications in hard tissue regeneration.

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

    Science.gov (United States)

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

    2015-06-01

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

  19. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Email Share Dialog × Print Children's Bone Health and Calcium: Condition Information What is bone health and how ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  20. Assay for calcium channels

    Energy Technology Data Exchange (ETDEWEB)

    Glossmann, H.; Ferry, D.R.

    1985-01-01

    This chapter focuses on biochemical assays for Ca/sup 2 +/-selective channels in electrically excitable membranes which are blocked in electrophysiological and pharmacological experiments by verapamil, 1,4-dihydropyridines, diltiazen (and various other drugs), as well as inorganic di- or trivalent cations. The strategy employed is to use radiolabeled 1,4-dihydropyridine derivatives which block calcium channels with ED/sub 50/ values in the nanomolar range. Although tritiated d-cis-diltiazem and verapamil can be used to label calcium channels, the 1,4-dihydropyridines offer numerous advantages. The various sections cover tissue specificity of channel labeling, the complex interactions of divalent cations with the (/sup 3/H)nimodipine-labeled calcium channels, and the allosteric regulation of (/sup 3/H)nimodipine binding by the optically pure enantiomers of phenylalkylamine and benzothiazepine calcium channel blockers. A comparison of the properties of different tritiated 1,4-dihydropyridine radioligands and the iodinated channel probe (/sup 125/I)iodipine is given.

  1. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500...

  2. Structural, thermal and optical characterization of an organic NLO material—Benzaldehyde thiosemicarbazone monohydrate single crystals

    Science.gov (United States)

    Santhakumari, R.; Ramamurthi, K.

    2011-02-01

    Single crystals of the organic NLO material, benzaldehyde thiosemicarbazone (BTSC) monohydrate, were grown by slow evaporation method. Solubility of BTSC monohydrate was determined in ethanol at different temperatures. The grown crystals were characterized by single crystal X-ray diffraction analysis to determine the cell parameters and by FT-IR technique to study the presence of the functional groups. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. UV-vis-NIR spectrum shows excellent transmission in the region of 200-1100 nm. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the optical nonlinearities of BTSC have been investigated by Z-scan technique with He-Ne laser radiation of wavelength 632.8 nm. Mechanical properties of the grown crystal were studied using Vickers microhardness tester. Second harmonic generation efficiency of the powdered BTSC monohydrate was tested using Nd:YAG laser and it is found to be ˜5.3 times that of potassium dihydrogen orthophosphate.

  3. The Plasma Membrane Calcium Pump

    Science.gov (United States)

    Rasmussen, H.

    1983-01-01

    Three aspect of cellular calcium metabolism in animal cells was discussed including the importance of the plasma membrane in calcium homeostasis, experiments dealing with the actual mechanism of the calcium pump, and the function of the pump in relationship to the mitochondria and to the function of calmodulin in the intact cell.

  4. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...

  5. Impregnating Coal With Calcium Carbonate

    Science.gov (United States)

    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.

  6. Effects of calcium source on biochemical properties of microbial CaCO3 precipitation

    Directory of Open Access Journals (Sweden)

    Jing eXu

    2015-12-01

    Full Text Available The biochemical properties of CaCO3 precipitation induced by Sporosarcina pasteurii, an ureolytic type microorganism, were investigated. Effects of calcium source on the precipitation process were examined, since calcium source plays a key role in microbiologically-induced mineralization. Regardless of the calcium source type, three distinct stages in the precipitation process were identified by Ca2+, NH4+, pH and cell density monitoring. Compared with stage 1 and 3, stage 2 was considered as the most critical part since biotic CaCO3 precipitation occurs during this stage. Kinetics studies showed that the microbial CaCO3 precipitation rate for calcium lactate was over twice of that for calcium nitrate, indicating that calcium lactate is more beneficial for the cell activity, which in turn determines urease production and CaCO3 precipitation. X-ray diffraction analysis confirmed the CaCO3 crystal as calcite, although scanning electron microscopy revealed a difference in crystal size and morphology if calcium source was different. The findings of this paper further suggest a promising application of microbiologically-induced CaCO3 precipitation in remediation of surface and cracks of porous media, e.g. cement-based composites, particularly by using organic source of calcium lactate.

  7. Size-dependent cellular uptake mechanism and cytotoxicity toward calcium oxalate on Vero cells

    Science.gov (United States)

    Sun, Xin-Yuan; Gan, Qiong-Zhi; Ouyang, Jian-Ming

    2017-02-01

    Urinary crystals with various sizes are present in healthy individuals and patients with kidney stone; however, the cellular uptake mechanism of calcium oxalate of various sizes has not been elucidated. This study aims to compare the internalization of nano-/micron-sized (50 nm, 100 nm, and 1 μm) calcium oxalate monohydrate (COM) and dihydrate (COD) crystals in African green monkey renal epithelial (Vero) cells. The internalization and adhesion of COM and COD crystals to Vero cells were enhanced with decreasing crystal size. Cell death rate was positively related to the amount of adhered and internalized crystals and exhibited higher correlation with internalization than that with adhesion. Vero cells mainly internalized nano-sized COM and COD crystals through clathrin-mediated pathways as well as micron-sized crystals through macropinocytosis. The internalized COM and COD crystals were distributed in the lysosomes and destroyed lysosomal integrity to some extent. The results of this study indicated that the size of crystal affected cellular uptake mechanism, and may provide an enlightenment for finding potential inhibitors of crystal uptake, thereby decreasing cell injury and the occurrence of kidney stones.

  8. Human dental microwear caused by calcium oxalate phytoliths in prehistoric diet of the lower Pecos region, Texas.

    Science.gov (United States)

    Danielson, D R; Reinhard, K J

    1998-11-01

    Recent research demonstrates that silica phytoliths of dietary origin are associated with microwear of human teeth. Previous research has shown that severe enamel microwear and dental wear characterizes Archaic hunter-gatherers in the lower Pecos region of west Texas. Calcium oxalate crystals are especially common in Archaic coprolites. The vast majority are derived from prickly pear and agave, which were the dietary staples in west Texas for 6,000 years. The calcium oxalate phytoliths are harder than enamel. Therefore, calcium oxalate crystals are the most likely source of previously documented dental microwear and wear in the lower Pecos region.

  9. Bulk crystal growth and nonlinear optical characterization of semiorganic single crystal: Cadmium (II) dibromide L - Proline monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Balakrishnan, T., E-mail: balacrystalgrowth@gmail.com [Crystal Growth Laboratory, PG & Research Department of Physics, Periyar EVR College (Autonomous), Tiruchirappalli, 620 023, Tamil Nadu (India); Sathiskumar, S. [Crystal Growth Laboratory, PG & Research Department of Physics, Periyar EVR College (Autonomous), Tiruchirappalli, 620 023, Tamil Nadu (India); Ramamurthi, K. [Crystal Growth and Thin Film Laboratory, Department of Physics and Nanotechnology, SRM University, Kattankulathur, 603 203, Kancheepuram, Tamil Nadu (India); Thamotharan, S. [Department of Bioinformatics, School of Chemical and Biotechnology, SASTRA University, Thanjavur, 613 401 (India)

    2017-01-15

    Single crystal of a novel metal organic nonlinear optical (NLO) cadmium (II) dibromide L - proline monohydrate (CBLPM) of size 7 × 7 × 5 mm{sup 3} was grown from slow evaporation technique. Single crystal X – ray diffraction analysis reveals that the crystal belongs to orthorhombic system with lattice parameters a = 10.1891 (8) Å, b = 13.4961 (11) Å, c = 7.4491 (5) Å and space group P2{sub 1}2{sub 1}2{sub 1}. The powder X – ray diffraction pattern of CBLPM was recorded and the X – ray diffraction peaks were indexed. The various functional groups of CBLPM were identified by the FT – IR and FT – Raman spectral analyses. The optical transmittance window and lower cut off wavelength of CBLPM were identified from UV – Vis – NIR studies. The mechanical strength of the grown crystal was estimated using Vickers microhardness test. Dielectric constant and dielectric loss measurements were carried out at different temperatures in the frequency range of 50 Hz - 2 MHz. The photoluminescence spectrum was recorded in the wavelength range 200–400 nm and the estimated optical band gap was ∼4.1 eV. Etching studies were carried out for different etching time. Thermal stability of CBLPM was determined using thermogravimetric analysis. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser. Size dependent second harmonic generation efficiency of the grown crystal was determined by Kurtz and Perry powder technique with different particle size using Nd:YAG laser with wavelength 1064 nm. Second harmonic generation efficiency of the powdered CBLPM crystal was ∼2.3 times that of potassium dihydrogen orthophosphate. - Highlights: • CBLPM crystal belongs to orthorhombic crystal system with space group P2{sub 1}2{sub 1}2{sub 1.} • Transmittance of CBLPM is ∼80% in the 650–1100 nm range. • Powder SHG efficiency of CBLPM increases with increase in particle size. • SHG efficiency of 0.57 μm size powdered CBLPM is ∼2

  10. Release of Crude Oil from Silica and Calcium Carbonate Surfaces

    DEFF Research Database (Denmark)

    Liu, Xiaoyan; Yan, Wei; Stenby, Erling Halfdan

    2016-01-01

    Adsorption and desorption of a North Sea crude oil to silica and calcium carbonate surfaces were studied by a quartz crystal microbalance, while the bare surfaces and adsorbed oil layers were characterized by atomic force microscopy and contact angle measurements. Water contact angles were measured...... on the bare surfaces, surfaces with an adsorbed oil layer, and surfaces after being exposed to aqueous salt solutions. This showed that the silica surface became more hydrophobic after oil adsorption, while the wettability of the calcium carbonate surface was not significantly changed by adsorption of an oil...... layer. A surface energy component analysis based on the acid base theory showed that oil adsorption on the surfaces depends upon apolar, acidic, and basic oil components of the crude oil and that the adsorbed oil components differ for adsorption to silica and calcium carbonate. Desorption of the crude...

  11. Calcium signaling in taste cells.

    Science.gov (United States)

    Medler, Kathryn F

    2015-09-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. The co-effect of collagen and magnesium ions on calcium carbonate biomineralization

    Energy Technology Data Exchange (ETDEWEB)

    Jiao Yunfeng [Department of Materials Science and Engineering, Biomaterials Laboratory, Tsinghua University, Beijing 100084 (China); Feng Qingling [Department of Materials Science and Engineering, Biomaterials Laboratory, Tsinghua University, Beijing 100084 (China)]. E-mail: biomater@mail.tsinghua.edu.cn; Li Xiaoming [Department of Materials Science and Engineering, Biomaterials Laboratory, Tsinghua University, Beijing 100084 (China)

    2006-05-15

    The process of calcium carbonate biomineralization in the solution containing collagen and magnesium ions was studied in this paper. The results were characterized by using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect rules were obtained by the cooperation of collagen and magnesium ions in different concentration. The experiment results showed that in the presence of both collagen and magnesium ions, aragonite and vaterite were precipitated at low Mg/Ca ion concentration ratio, while only aragonite with regular spherical morphology was precipitated at high Mg/Ca ion concentration ratio. It indicated that collagen has a promotional effect on magnesium ions in controlling the polymorph of calcium carbonate crystal. A much wider range of calcium carbonate morphologies was observed in the presence of both collagen and magnesium ions. The experiments suggested that collagen acts in combination with magnesium ions to inhibit calcite crystal growth, while favoring the formation of aragonite crystals.

  13. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  14. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P platelet free calcium (intracellular calcium concentration) were also reduced (P metabolism (P metabolism are relatively impervious to dietary calcium in the short term, 2) increased ionized calcium did not normalize low-calcium-induced elevations of BP, and 3) parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  15. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  16. Crystal phases of calcium carbonate within otoliths of Cyprinus ...

    African Journals Online (AJOL)

    Yomi

    2012-04-26

    Campana and Neilson., 1985). Plenty of information recorded in otoliths have been studied to resolve fish ecological questions such as fish age, feeding and growth history, recruitment and migration, mortality and stock structure, ...

  17. Assessment of microarchitecture and crystal structure of hydroxyapatite in osteoporosis

    OpenAIRE

    Zairin Noor; Sumitro, Sutiman B.; Mohammad Hidayat; Agus Hadian Rahim; Ahmad Taufiq

    2011-01-01

    Osteoporosis is characterized by lower bone mineral density (BMD) and microarchitectural degeneration, which tends to increase bone fragility and fracture risk. Bone microstructure depends on interactions between the mineral atoms, which may perform substitution or incorporation into bone crystals, and may dynamically take over the function of calcium or may become a complementary part. The mineral atoms may also become a composite in the hydroxyapatite crystals. The aim of this study was to ...

  18. Precipitation of calcium, magnesium, strontium and barium in tissues of four Acacia species (Leguminosae: Mimosoideae).

    Science.gov (United States)

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

    2012-01-01

    Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory.

  19. Precipitation of Calcium, Magnesium, Strontium and Barium in Tissues of Four Acacia Species (Leguminosae: Mimosoideae)

    Science.gov (United States)

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

    2012-01-01

    Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells), pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory. PMID:22848528

  20. Precipitation of calcium, magnesium, strontium and barium in tissues of four Acacia species (Leguminosae: Mimosoideae.

    Directory of Open Access Journals (Sweden)

    Honghua He

    Full Text Available Precipitation of calcium in plants is common. There are abundant studies on the uptake and content of magnesium, strontium and barium, which have similar chemical properties to calcium, in comparison with those of calcium in plants, but studies on co-precipitation of these elements with calcium in plants are rare. In this study, we compared morphologies, distributional patterns, and elemental compositions of crystals in tissues of four Acacia species grown in the field as well as in the glasshouse. A comparison was also made of field-grown plants and glasshouse-grown plants, and of phyllodes of different ages for each species. Crystals of various morphologies and distributional patterns were observed in the four Acacia species studied. Magnesium, strontium and barium were precipitated together with calcium, mainly in phyllodes of the four Acacia species, and sometimes in branchlets and primary roots. These elements were most likely precipitated in forms of oxalate and sulfate in various tissues, including epidermis, mesophyll, parenchyma, sclerenchyma (fibre cells, pith, pith ray and cortex. In most cases, precipitation of calcium, magnesium, strontium and barium was biologically induced, and elements precipitated differed between soil types, plant species, and tissues within an individual plant; the precipitation was also related to tissue age. Formation of crystals containing these elements might play a role in regulating and detoxifying these elements in plants, and protecting the plants against herbivory.

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

    Science.gov (United States)

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

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

  2. Photoluminescent calcium azolium carboxylates with diversified calcium coordination geometry and thermal stability.

    Science.gov (United States)

    Suresh, Paladugu; Babu, Chatla Naga; Sampath, Natarajan; Prabusankar, Ganesan

    2015-04-28

    Despite the popularity and versatility of transition-metal–azolium carboxylate coordination polymers, there are very few examples of group 2 complexes supported by azolium carboxylate ligands in the literature, and there are none featuring luminescent calcium azolium carboxylates. New ionic calcium coordination networks, {[Ca2(L(1))2(H2O)4](Br)4·6H2O}∞ (1), {[(L(3))2Ca(H2O)2]2(Br)2}∞ (3), {[(L(4))2Ca(H2O)2]2(Br)2}∞ (4), and {[(L(5))2Ca3(Na)(H2O)9(Cl)](Br)6·2H2O}∞ (5) along with binuclear {[Ca2(L(2))2(H2O)9](Br)4·4H2O} (2), and trinuclear {[(L(6))2Ca3(H2O)9](Br)6} (6) were isolated from the reaction between the corresponding azolium carboxylates and calcium carbonate in aqueous solution. 1–6 were characterized by FT-IR, NMR, TGA, UV-vis, fluorescence and single crystal X-ray diffraction techniques. Interestingly, the first tetra-cationic binuclear calcium 2 was isolated using L(2)H2Br2 and hexa-cationic trinuclear calcium 6 was isolated using L(6)H3Br3. The 3D coordination polymers 1 and 4 were derived with the help of L(1)H2Br2 and L(4)H2Br2, respectively, through Br···H hydrogen bonding. The 3D MOF 3 with rhomboidal channels was constructed using L(3)H2Br2, where the channel size is about 4.8 × 2.9 nm. 5 was isolated as a rare 1D coordination polymer. The choice of azolium carboxylates in these solids not only changes the topology of the network but also affects the chemistry exhibited by the network. Calcium azolium carboxylate assemblies 1–4 and 6 exhibit interesting solid-state photoluminescence properties, driven by azolium carboxylate ligands. Variation of the bridging chromophore produced significant effects on the fluorescence properties. 1–4 and 6 represent the first examples of luminescent calcium azolium carboxylate complexes. As can be seen in the six metal–organic assemblies presented in this report, a combination of carboxylate groups and steric hindrance affects the topology and physical properties of the resultant solids.

  3. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    OpenAIRE

    Bizzozero, Julien; Scrivener, Karen

    2015-01-01

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate ...

  4. Mixed calcium-magnesium pre-nucleation clusters enrich calcium

    OpenAIRE

    Verch, Andreas; Antonietti, Markus; Cölfen, Helmut

    2012-01-01

    It is demonstrated that magnesium and carbonate ions can form pre-nucleation clusters in analogy to calcium carbonate. If a mixed calcium and magnesium solution is brought in contact with carbonate ions, mixed pre-nucleation clusters form. The equilibrium constants for their formation are reported revealing that over the entire range of possible cation mixing ratios, calcium gets enriched over magnesium in the pre-nucleation clusters. This can explain high magnesium contents in amorphous calc...

  5. Calcium-dependent freezing tolerance in Arabidopsis involves membrane resealing via synaptotagmin SYT1.

    Science.gov (United States)

    Yamazaki, Tomokazu; Kawamura, Yukio; Minami, Anzu; Uemura, Matsuo

    2008-12-01

    Plant freezing tolerance involves the prevention of lethal freeze-induced damage to the plasma membrane. We hypothesized that plant freezing tolerance involves membrane resealing, which, in animal cells, is accomplished by calcium-dependent exocytosis following mechanical disruption of the plasma membrane. In Arabidopsis thaliana protoplasts, extracellular calcium enhanced not only freezing tolerance but also tolerance to electroporation, which typically punctures the plasma membrane. However, calcium did not enhance survival when protoplasts were exposed to osmotic stress that mimicked freeze-induced dehydration. Calcium-dependent freezing tolerance was also detected with leaf sections in which ice crystals intruded into tissues. Interestingly, calcium-dependent freezing tolerance was inhibited by extracellular addition of an antibody against the cytosolic region of SYT1, a homolog of synaptotagmin known to be a calcium sensor that initiates exocytosis. This inhibition indicates that the puncture allowing the antibody to flow into the cytoplasm occurs during freeze/thawing. Thus, we propose that calcium-dependent freezing tolerance results from resealing of the punctured site. Protoplasts or leaf sections isolated from Arabidopsis SYT1-RNA interference (RNAi) plants lost calcium-dependent freezing tolerance, and intact SYT1-RNAi plants had lower freezing tolerance than control plants. Taken together, these findings suggest that calcium-dependent freezing tolerance results from membrane resealing and that this mechanism involves SYT1 function.

  6. Urinary metals in a spontaneous canine model of calcium oxalate urolithiasis.

    Directory of Open Access Journals (Sweden)

    Eva Furrow

    Full Text Available Calcium oxalate urolithiasis is a common and painful condition in people. The pathogenesis of this disease is complex and poorly understood. Laboratory animal and in vitro studies have demonstrated an effect of multiple trace metals in the crystallization process, and studies in humans have reported relationships between urinary metal concentrations and stone risk. Dogs are a spontaneous model of calcium oxalate urolithiasis, and the metal content of canine calcium oxalate stones mirrors that of human stones. The aim of this study was to test for a relationship between urinary metals and calcium oxalate urolithiasis in dogs. We hypothesized that urinary metals would differ between dogs with and without calcium oxalate urolithiasis. Urine from 122 dogs (71 cases and 51 stone-free controls was analyzed for calcium and 12 other metals. The cases had higher urinary calcium, copper, iron, and vanadium and lower urinary cobalt. Higher urinary vanadium in the cases was associated with being fed a therapeutic stone-prevention diet. Urinary calcium had a strong positive correlation with strontium and moderate positive correlations with chromium, nickel, and zinc. The results of this study complement the findings of similar human studies and suggest a potential role of trace metals in calcium oxalate urolithiasis. Further investigation into how trace metals may affect stone formation is warranted.

  7. Biological Reactions to Calcium Phosphate-coated Calcium Carbonate Particles

    National Research Council Canada - National Science Library

    Tetsunari NISHIKAWA; Kazuya MASUNO; Tomoharu OKAMURA; Kazuya TOMINAGA; Masahiro WATO; Mayu KOKUBU; Koichi IMAI; Shoji TAKEDA; Yoichro TAGUCHI; Masatoshi UEDA; Akio TANAKA

    2010-01-01

    [SYNOPSIS][Objectives]: In order to histopathologically investigate biological reactions to materials used for scaffolds, we examined the cytotoxicity to calcium particles in vitro and bioabsorption in vivo...

  8. Effect of Phosphate Inhibitors on the Formation of Lead Phosphate/Carbonate Nanorods, Microrods and Dendritic Structures

    Science.gov (United States)

    There are several factors which influence the corrosion rate of lead, which in turn morphs into different crystal shapes and sizes. Some of the important factors are: alkalinity, pH, calcium, orthophosphate and silica. Low to moderate alkalinity decreases corrosion rates, while ...

  9. Osteoporosis, calcium and physical activity.

    OpenAIRE

    Martin, A. D.; Houston, C S

    1987-01-01

    Sales of calcium supplements have increased dramatically since 1983, as middle-aged women seek to prevent or treat bone loss due to osteoporosis. However, epidemiologic studies have failed to support the hypothesis that larger amounts of calcium are associated with increased bone density or a decreased incidence of fractures. The authors examine the evidence from controlled trials on the effects of calcium supplementation and physical activity on bone loss and find that weight-bearing activit...

  10. Cardiovascular Effects of Calcium Supplements

    Directory of Open Access Journals (Sweden)

    Ian R. Reid

    2013-07-01

    Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

  11. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

    ...) technology selective laser sintering (SLS). BME has successfully implemented a pilot facility to fabricate calcium phosphate implants using anatomical data coupled with the selective laser sintering process...

  12. 21 CFR 73.1070 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... precipitated calcium carbonate (CaCO3). (2) Color additive mixtures for drug use made with calcium carbonate... precipitated calcium carbonate in the United States Pharmacopeia XX (1980). (c) Uses and restrictions. Calcium... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food...

  13. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium carbonate. 184.1191 Section 184.1191 Food... Specific Substances Affirmed as GRAS § 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation...

  14. Comparison of Precipitated Calcium Carbonate/Polylactic Acid and Halloysite/Polylactic Acid Nanocomposites

    OpenAIRE

    Xuetao Shi; Guangcheng Zhang; Cristina Siligardi; Guido Ori; Andrea Lazzeri

    2015-01-01

    PLA nanocomposites with stearate coated precipitated calcium carbonate (PCC) and halloysite natural nanotubes (HNT) were prepared by melt extrusion. The crystallization behavior, mechanical properties, thermal dynamical mechanical analysis (DMTA), and the morphology of the PCC/PLA, HNT/PLA, and HNT/PCC/PLA composites were discussed. Compared to halloysite nanotubes, PCC nanoparticles showed a better nucleating effect, which decreased both the glass transition and cold crystallization temperat...

  15. Crystallization process

    Science.gov (United States)

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  16. Calcium signalling: fishing out molecules of mitochondrial calcium transport.

    Science.gov (United States)

    Hajnóczky, György; Csordás, György

    2010-10-26

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins - MICU1, NCLX and LETM1 - to the previously unknown molecular mechanism of mitochondrial calcium transport. Copyright © 2010 Elsevier Ltd. All rights reserved.

  17. Calcium electroporation in three cell lines; a comparison of bleomycin and calcium, calcium compounds, and pulsing conditions

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille

    2013-01-01

    BACKGROUND: Electroporation with calcium (calcium electroporation) can induce ATP depletion-associated cellular death. In the clinical setting, the cytotoxic drug bleomycin is currently used with electroporation (electrochemotherapy) for palliative treatment of tumors. Calcium electroporation off...

  18. Sucrose/bovine serum albumin mediated biomimetic crystallization ...

    Indian Academy of Sciences (India)

    To understand the role of the sucrose/bovine serum albumin system in the biomineralization process, we have tested the influence of different concentration of the sucrose/bovine serum albumin (BSA) on calcium carbonate (CaCO3) precipitation. The CaCO3 crystals were characterized by scanning electron microscope ...

  19. [Pathophysiology, diagnosis and conservative therapy in calcium kidney calculi].

    Science.gov (United States)

    Hess, B

    2003-02-01

    Annual incidences of kidney stones are about 0.1-0.4% of the population, and lifetime prevalences in the USA and Europe range between 8 and 15%. Kidney stones occur more frequently with increasing age and among men. Within ten years, the disease usually recurs in more than 50% of patients. Nowadays, about 85% of all kidney stones contain calcium salts (calcium oxalate and/or calcium phosphate) as their main crystalline components. Because human urine is commonly supersaturated with respect to calcium salts as well as to uric acid, crystalluria is very common, i.e. healthy people excrete up to ten millions of microcrystals every day. Recurrent stone formers appear to excrete lower amounts or structurally defective forms of crystallization inhibitors which allows for the formation of large crystal aggregates as precursors of stones. Alternatively, crystal adhesion to urothelial surfaces may be enhanced in stone formers. Medical treatment of renal colic is based on nonsteroidal antiinflammatory drugs, because prostaglandins appear to play a crucial role in the pathophysiology of pain during ureteral obstruction. In addition, centrally acting analgesics such as pethidine-HCl may be required in many cases. The administration of high amounts (3-4 liters/day) of intravenous fluids should be abandoned, since it may raise intraureteral pressure whereby pain increases and kidney pelvis or fornices may rupture. All first-stone formers should undergo a simple basic evaluation, including stone analysis (x-ray diffraction or infrared spectrometry), serum values of ionized calcium (alternatively: total calcium and albumin) and creatinine, urinalysis and repeated measurements of fasting urine pH in order to detect urinary acidification disorders or low urine pH. In high-risk patients with as first stone episode (i.e. strongly positive family history, inflammatory bowel disease, short-bowel syndrome, nephrocalcinosis, bilateral stones, hypercalcemia, renal tubular acidosis, airline

  20. Preliminary study on crystal dissolution activity of Rotula aquatica, Commiphora wightii and Boerhaavia diffusa extracts.

    Science.gov (United States)

    Raut, Ashwinikumar A; Sunder, Sudha; Sarkar, Subrata; Pandita, Nancy S; Vaidya, Ashok D B

    2008-12-01

    Several Ayurvedic plants are known to have activity against diverse urinary crystals. The traditional knowledge of Ayurveda, collective clinical experience in arthritis and the earlier experimental studies on urinary crystals led to the selection of three plants, viz. Rotula aquatica, Commiphora wightii Bhandari syn. C.mukul. and Boerhaavia diffusa for screening anticrystal activity against basic calcium phosphate (BCP), calcium pyrophosphate (CPPD) and monosodium urate monohydrate (MSUM). The effects of each plant were assayed on microcrystals in 24-well microplates in vitro. Our results show that the aqueous extracts of only R. aquatica and C. wightii have shown crystal dissolving activity against MSUM.

  1. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000490.htm Calcium, vitamin D, and your bones To use the sharing ... and maintain strong bones. How Much Calcium and Vitamin D do I Need? Amounts of calcium are ...

  2. Calcium Supplements: Do Men Need Them Too?

    Science.gov (United States)

    ... Lifestyle Nutrition and healthy eating Should men take calcium supplements? Answers from Katherine Zeratsky, R.D., L. ... Most healthy men don't need to take calcium supplements. Calcium is important for men for optimal ...

  3. Amorphous calcium carbonate particles form coral skeletons

    Science.gov (United States)

    Mass, Tali; Giuffre, Anthony J.; Sun, Chang-Yu; Stifler, Cayla A.; Frazier, Matthew J.; Neder, Maayan; Tamura, Nobumichi; Stan, Camelia V.; Marcus, Matthew A.; Gilbert, Pupa U. P. A.

    2017-09-01

    Do corals form their skeletons by precipitation from solution or by attachment of amorphous precursor particles as observed in other minerals and biominerals? The classical model assumes precipitation in contrast with observed “vital effects,” that is, deviations from elemental and isotopic compositions at thermodynamic equilibrium. Here, we show direct spectromicroscopy evidence in Stylophora pistillata corals that two amorphous precursors exist, one hydrated and one anhydrous amorphous calcium carbonate (ACC); that these are formed in the tissue as 400-nm particles; and that they attach to the surface of coral skeletons, remain amorphous for hours, and finally, crystallize into aragonite (CaCO3). We show in both coral and synthetic aragonite spherulites that crystal growth by attachment of ACC particles is more than 100 times faster than ion-by-ion growth from solution. Fast growth provides a distinct physiological advantage to corals in the rigors of the reef, a crowded and fiercely competitive ecosystem. Corals are affected by warming-induced bleaching and postmortem dissolution, but the finding here that ACC particles are formed inside tissue may make coral skeleton formation less susceptible to ocean acidification than previously assumed. If this is how other corals form their skeletons, perhaps this is how a few corals survived past CO2 increases, such as the Paleocene-Eocene Thermal Maximum that occurred 56 Mya.

  4. Calcium carbonate mineralization: involvement of extracellular polymeric materials isolated from calcifying bacteria.

    Science.gov (United States)

    Ercole, Claudia; Bozzelli, Paola; Altieri, Fabio; Cacchio, Paola; Del Gallo, Maddalena

    2012-08-01

    This study highlights the role of specific outer bacterial structures, such as the glycocalix, in calcium carbonate crystallization in vitro. We describe the formation of calcite crystals by extracellular polymeric materials, such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) isolated from Bacillus firmus and Nocardia calcarea. Organic matrices were isolated from calcifying bacteria grown on synthetic medium--in the presence or absence of calcium ions--and their effect on calcite precipitation was assessed. Scanning electron microscopy observations and energy dispersive X-ray spectrometry analysis showed that CPS and EPS fractions were involved in calcium carbonate precipitation, not only serving as nucleation sites but also through a direct role in crystal formation. The utilization of different synthetic media, with and without addition of calcium ions, influenced the biofilm production and protein profile of extracellular polymeric materials. Proteins of CPS fractions with a molecular mass between 25 and 70 kDa were overexpressed when calcium ions were present in the medium. This higher level of protein synthesis could be related to the active process of bioprecipitation.

  5. Corrosion and solubility in a TSP-buffered chemical environment following a loss of coolant accident: Part 3—Calcium

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Sterling; Ali, Amir; LaBrier, Daniel [Department of Nuclear Engineering, University of New Mexico (United States); Blandford, Edward D, E-mail: edb@unm.edu [Department of Nuclear Engineering, University of New Mexico (United States); Howe, Kerry [Department of Civil Engineering, University of New Mexico (United States)

    2016-04-15

    four distinct (and progressive) temporal regions: prompt release, metastable, autocatalytic drop, and stable release region. The prompt calcium release rate and maximum calcium concentration in solution are both dependent on the initial fiberglass concentration. Thermodynamic modeling of calcium orthophosphates determined that the most probable precipitates in the metastable and stable region were calcium-deficient hydroxyapatite (CDHA) and β-tricalcium phosphate (β-TCP). Magnesium that leached from NUKON fiberglass was determined to control the initiation of the autocatalytic drop region; in all long period leaching tests, a Mg:Ca molar ratio of 1.9 existed prior to the autocatalytic drop. Although head-loss resulting from calcium leaching is not the focus of this research, the head-loss change under high-temperature vertical column corresponding to in-situ leaching of calcium from NUKON fiber is reported. The measured head-loss (temperature corrected to 20 °C) steadily increased from 1.1 kPa (4.4′′ H{sub 2}O) to 3.1 kPa (12.2′′ H{sub 2}O) over an experimental period of 20 days.

  6. Adsorption characteristics of amino acids on to calcium oxalate.

    Science.gov (United States)

    He, Junbin; Lin, Rihui; Long, Han; Liang, Yuwei; Chen, Yangyang

    2015-09-15

    Adsorption of amino acids on to calcium oxalate found in urinary calculus has been studied and the adsorption characteristics were analyzed. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit the kinetics data. The pseudo-second-order model best described the dynamic behavior of the adsorption process. The uptake of glutamic acid and aspartic acid were found to decrease as solution pH increasing from 4 to 8. The experimental data obtained at different pH conditions were analyzed and fitted by Langmuir, Freundlich, Redlich-Peterson, Temkin and Sips isotherm models using linear and nonlinear regression analysis. Error analysis (correlation coefficient, residual root mean square error and chi-square test) showed that the Langmuir I isotherm model and the non-linear form of Sips isotherm model should be primarily adopted for fitting the equilibrium data. The maximum adsorption capacity of glutamic acid and aspartic acid onto calcium oxalate monohydrate crystals are 0.059 and 0.066μmol/g at pH 4, respectively. These studies have the vital significance for research aimed at exploring the role of urinary amino acids effect the formation process of calcium oxalate crystals found in urinary calculus and for potential application in the design of synthetic peptides used for urinary calculi therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Transformation of Amorphous Calcium Phosphate to Crystalline Dahllite in the Radular Teeth of Chitons

    Science.gov (United States)

    Lowenstam, H. A.; Weiner, S.

    1985-01-01

    A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The c axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface.

  8. Novel tea polyphenol-modified calcium phosphate nanoparticle and its remineralization potential

    NARCIS (Netherlands)

    He, L.; Deng, D.; Zhou, X.; Cheng, L.; ten Cate, J.M.; Li, J.; Li, X.; Crielaard, W.

    2015-01-01

    Tea polyphenols (TP) are not only potent antimicrobial and antioxidant agents but also effective modifiers in the formation of nanosized crystals. Since nano-hydroxyapatite (n-HA) is known to enhance remineralization of dental hard tissue, our aims were to synthesize nanosized calcium phosphate

  9. Effect of calcium and carbonate concentrations on anionic membrane fouling during electrodialysis.

    Science.gov (United States)

    Araya-Farias, Monica; Bazinet, Laurent

    2006-04-01

    A previous study on electrodialysis of calcium and carbonate high concentration solutions demonstrated that calcium migrated through the cation-exchange membrane (CEM) was blocked by the anion-exchange membrane (AEM) where it formed another fouling. The aim of the present work was to complete the identification of the deposit formed on AEM during electrodialysis and to characterize its physical structure at the interface of the membrane. No fouling was found on the anionic membranes treated without calcium chloride in presence of sodium carbonate, while membranes used during ED process of solutions containing calcium chloride and sodium carbonate were slightly fouled. A thin layer of precipitates was observed on the anionic membrane surface. The appearance of precipitates was typical of a crystalline substance. The size and form of crystal increased in proportion to the concentration of calcium chloride in solution. Large and cubic crystals were the best defined on the membrane treated at 1600 mg/L of CaCl2. The precipitate was identified as calcium hydroxide. However, this fouling was not found to affect significantly the electrical conductivity and the thickness of the membranes. Furthermore, the fouling formed was reversible.

  10. DHS Internship Summary-Crystal Assembly at Different Length Scales

    Energy Technology Data Exchange (ETDEWEB)

    Mishchenko, L

    2009-08-06

    I was part of a project in which in situ atomic force microscopy (AFM) was used to monitor growth and dissolution of atomic and colloidal crystals. At both length scales, the chemical environment of the system greatly altered crystal growth and dissolution. Calcium phosphate was used as a model system for atomic crystals. A dissolution-reprecipitation reaction was observed in this first system, involving the conversion of brushite (DCPD) to octacalcium phosphate (OCP). In the second system, polymeric colloidal crystals were dissolved in an ionic solvent, revealing the underlying structure of the crystal. The dissolved crystal was then regrown through an evaporative step method. Recently, we have also found that colloids can be reversibly deposited in situ onto an ITO (indium tin oxide) substrate via an electrochemistry setup. The overall goal of this project was to develop an understanding of the mechanisms that control crystallization and order, so that these might be controlled during material synthesis. Controlled assembly of materials over a range of length scales from molecules to nanoparticles to colloids is critical for designing new materials. In particular, developing materials for sensor applications with tailorable properties and long range order is important. In this work, we examine two of these length scales: small molecule crystallization of calcium phosphate (whose crystal phases include DCPD, OCP, and HAP) and colloidal crystallization of Poly(methyl methacrylate) beads. Atomic Force Microscopy is ideal for this line of work because it allows for the possibility of observing non-conducting samples in fluid during growth with high resolution ({approx} 10 nm). In fact, during atomic crystal growth one can observe changes in atomic steps, and with colloidal crystals, one can monitor the individual building blocks of the crystal. Colloids and atoms crystallize under the influence of different forces acting at different length scales as seen in Table 1

  11. Calcium pyrophosphate dihydrate deposition disease (CPPD/Pseudogout of the temporomandibular joint - FNA findings and microanalysis.

    Directory of Open Access Journals (Sweden)

    Naqvi Asghar

    2008-01-01

    Full Text Available We report a case of a Calcium pyrophosphate dihydrate deposition disease (CPPD presenting as a mass in the parotid and temporomandibular joint (TMJ that simulated a parotid tumor. A 35 year-old man presented with pain in the left ear area. A CT Scan of the area showed a large, calcified mass surrounding the left condylar head, and extending into the infratemporal fossa. FNA of the mass showed birefringent crystals, most of which were rhomboid with occasional ones being needle shaped, embedded in an amorphous pink substance. Scanning electron microscopy (SEM with energy dispersive x-ray spectroscopy (EDS of these crystals showed peaks corresponding to calcium and phosphorus. SEM/EDS is a rapid method of diagnosing calcium pyrophosphate dihydrate deposition disease (CPPD and an alternative to more commonly used method of special staining of cell block sections coupled with polarizing microscopy.

  12. Preparation of hierarchically organized calcium phosphate–organic polymer composites by calcification of hydrogel

    Directory of Open Access Journals (Sweden)

    Kozue Furuichi, Yuya Oaki, Hirofumi Ichimiya, Jun Komotori and Hiroaki Imai

    2006-01-01

    Full Text Available A novel type of calcium phosphate–organic polymer composite having a hierarchical structure was prepared by calcification of a poly(acrylic acid hydrogel. Macroscopically, an organic gel containing phosphate ions was transformed into an opaque solid material by diffusion of calcium ions. We observed the formation of micrometer-scale layered structures consisting of nanoscale crystals of hydroxylapatite (HAp in the opaque products. The laminated architecture resulting from the periodic precipitation of calcium phosphate varied with the reaction conditions, such as the concentrations of the precursor ions and the density of the gel. The nanoscopic structure of HAp crystals was modified by the addition of gelatin to the polymer matrix.

  13. Calcium metabolism & hypercalcemia in adults.

    Science.gov (United States)

    Lumachi, F; Motta, R; Cecchin, D; Ave, S; Camozzi, V; Basso, S M M; Luisetto, G

    2011-01-01

    Calcium is essential for many metabolic process, including nerve function, muscle contraction, and blood clotting. The metabolic pathways that contribute to maintain serum calcium levels are bone remodeling processes, intestinal absorption and secretion, and renal handling, but hypercalcemia occurs when at least 2 of these 3 metabolic pathways are altered. Calcium metabolism mainly depends on the activity of parathyroid hormone (PTH). Its secretion is strictly controlled by the ionized serum calcium levels through a negative feed-back, which is achieved by the activation of calcium-sensing receptors (CaSRs) mainly expressed on the surface of the parathyroid cells. The PTH receptor in bone and kidney is now referred as PTHR1. The balance of PTH, calcitonin, and vitamin D has long been considered the main regulator of calcium metabolism, but the function of other actors, such as fibroblast growth factor-23 (FGF-23), Klotho, and TPRV5 should be considered. Primary hyperparathyroidism and malignancy are the most common causes of hypercalcemia, accounting for more than 90% of cases. Uncontrolled hypercalcemia may cause renal impairment, both temporary (alteration of renal tubular function) and progressive (relapsing nephrolithiasis), leading to a progressive loss of renal function, as well as severe bone diseases, and heart damages. Advances in the understanding of all actors of calcium homeostasis will be crucial, having several practical consequences in the treatment and prevention of hypercalcemia. This would allow to move from a support therapy, sometimes ineffective, to a specific and addressed therapy, especially in patients with chronic hypercalcemic conditions unsuitable for surgery.

  14. Molecular mechanisms of pain in crystal-induced arthritis.

    Science.gov (United States)

    Ramonda, R; Oliviero, F; Galozzi, P; Frallonardo, P; Lorenzin, M; Ortolan, A; Scanu, A; Punzi, L

    2015-02-01

    Crystal-induced arthritis (CIA) is characterized by an intense inflammatory reaction triggered by the deposition of monosodium urate, calcium pyrophosphate, and basic calcium phosphate crystals in articular and periarticular tissues. Severe, acute pain constitutes the most important clinical symptom in patients affected by these diseases. Pain along with redness, warmness, swelling, and stiffness in the affected joint arises abruptly in gout and disappears when the acute phase of the attack resolves. While an acute joint attack caused by calcium pyrophosphate crystals can mimic a gout flare, basic calcium phosphate crystal arthritis gives rise to a series of clinical manifestations, the most severe of which are calcific periarthritis, mostly asymptomatic, and a highly destructive arthritis known as Milwaukee shoulder syndrome, which is characterized by painful articular attacks. Pain development in CIA is mediated by several inflammatory substances that are formed after cell injury by crystals. The most important of these molecules, which exert their effects through different receptor subtypes present in both peripheral sensory neurons and the spinal cord, are prostaglandins, bradykinin, cytokines (in particular, interleukin (IL)-1β), and substance P. The pharmacological treatment of pain in CIA is strictly associated with the treatment of acute phases and flares of the disease, during which crystals trigger the inflammatory response. According to international guidelines, colchicines, nonsteroidal anti-inflammatory drugs, and/or corticosteroids are first-line agents for the systemic treatment of acute CIA, while biologics, namely anti-IL-1β agents, should be used only in particularly refractory cases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Mixed crystal organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  16. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... Duyff RL. American Dietetic Association Complete Food and Nutrition Guide. 4th ed. Hoboken, N.J.: John Wiley & Sons; 2012:140. Rosen HN. Calcium and vitamin D supplementation in osteoporosis. http://www.uptodate.com/home/index. ...

  17. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    Energy Technology Data Exchange (ETDEWEB)

    Yang Liang; Habibovic, Pamela; Van Blitterswijk, Clemens A [Department of Tissue Regeneration, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Hedhammar, My; Johansson, Jan [Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, the Biomedical Centre, Box 575, 751 23 Uppsala (Sweden); Blom, Tobias; Leifer, Klaus [Department of Engineering Sciences, Uppsala University, Box 534, S-751 21 Uppsala (Sweden)

    2010-08-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  18. Optimization of calcium phosphate fine ceramic powders preparation

    Science.gov (United States)

    Sezanova, K.; Tepavitcharova, S.; Rabadjieva, D.; Gergulova, R.; Ilieva, R.

    2013-12-01

    The effect of biomimetic synthesis method, reaction medium and further precursor treatments on the chemical and phase composition, crystal size and morphology of calcium phosphates was examined. Nanosized calcium phosphate precursors were biomimetically precipitated by the method of continuous precipitation in three types of reaction media at pH 8: (i) SBF as an inorganic electrolyte system; (ii) organic (glycerine) modified SBF (volume ratio of 1:1); (iii) polymer (10 g/l xanthan gum or 10 g/l guar gum) modified SBF (volume ratio of 1:1). After maturation (24 h) the samples were lyophilized, calcinated at 300°C for 3 hours, and washed with water, followed by new gelation, lyophilization and step-wise (200, 400, 600, 800, and 1000°C, each for 3 hours) sintering. The reaction medium influenced the chemical composition and particle size but not the morphology of the calcium phosphate powders. In all studied cases bi-phase calcium phosphate fine powders with well-shaped spherical grains, consisting of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) with a Ca/P ratio of 1.3 - 1.6 were obtained. The SBF modifiers decreased the particle size of the product in the sequence guar gum ˜ xanthan gum < glycerin < SBF medium.

  19. Epitaxial Relationships between Calcium Carbonate and Inorganic Substrates

    Directory of Open Access Journals (Sweden)

    Taewook Yang

    2014-09-01

    Full Text Available 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 (α-Al2O3, α-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.

  20. Pressure cryocooling protein crystals

    Science.gov (United States)

    Kim, Chae Un [Ithaca, NY; Gruner, Sol M [Ithaca, NY

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  1. 21 CFR 184.1187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH control...

  2. Extracellular and Intracellular Regulation of Calcium Homeostasis

    Directory of Open Access Journals (Sweden)

    Felix Bronner

    2001-01-01

    Full Text Available An organism with an internal skeleton must accumulate calcium while maintaining body fluids at a well-regulated, constant calcium concentration. Neither calcium absorption nor excretion plays a significant regulatory role. Instead, isoionic calcium uptake and release by bone surfaces causes plasma calcium to be well regulated. Very rapid shape changes of osteoblasts and osteoclasts, in response to hormonal signals, modulate the available bone surfaces so that plasma calcium can increase when more low-affinity bone calcium binding sites are made available and can decrease when more high-affinity binding sites are exposed. The intracellular free calcium concentration of body cells is also regulated, but because cells are bathed by fluids with vastly higher calcium concentration, their major regulatory mechanism is severe entry restriction. All cells have a calcium-sensing receptor that modulates cell function via its response to extracellular calcium. In duodenal cells, the apical calcium entry structure functions as both transporter and a vitamin D–responsive channel. The channel upregulates calcium entry, with intracellular transport mediated by the mobile, vitamin D–dependent buffer, calbindin D9K, which binds and transports more than 90% of the transcellular calcium flux. Fixed intracellular calcium binding sites can, like the body's skeleton, take up and release calcium that has entered the cell, but the principal regulatory tool of the cell is restricted entry.

  3. Calcium phosphates for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

    2017-07-01

    The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

  4. Polysulfide calcium as multyfunctional product

    Directory of Open Access Journals (Sweden)

    G. Abramova

    2012-12-01

    Full Text Available A modified method of producing of polysulfide calcium, the influence of various factors on the degree of polysulfide of product, as well as possible directions for its use as a multifunctional compound were considered.

  5. [Calcium metabolism after the menopause].

    Science.gov (United States)

    Kanovitch, D; Klotz, H P

    1976-02-16

    The authors recall the antagonism between estradiol and parathormone. Estradiol tends to lower serum calcium and fix calcium in the bones as shown by one of us 25 years ago. The mechanism of this action of estrogen on calcium metabolism has been determined by numerous authors but some points are still not clear, e.g. the interferences between estrogen and calcitonin. Classically, parathormone is known to increase bony reabsorption and raise serum calcium. After the menopause the gradual reduction in estradiol secretion leads to post-menopausal osteoporosis. It is better to administer estrogens prophylactically to women after the menopause provided a cervical smear and mammography have been carried out to eliminate latent carcinoma of the breast or uterine cervix.

  6. Calcium-sensing beyond neurotransmitters

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Han, Weiping

    2009-01-01

    Neurotransmitters, neuropeptides and hormones are released through the regulated exocytosis of SVs (synaptic vesicles) and LDCVs (large dense-core vesicles), a process that is controlled by calcium. Synaptotagmins are a family of type 1 membrane proteins that share a common domain structure. Most....... Also, we discuss potential roles of synaptotagmins in non-traditional endocrine systems....... synaptotagmins are located in brain and endocrine cells, and some of these synaptotagmins bind to phospholipids and calcium at levels that trigger regulated exocytosis of SVs and LDCVs. This led to the proposed synaptotagmin-calcium-sensor paradigm, that is, members of the synaptotagmin family function...... as calcium sensors for the regulated exocytosis of neurotransmitters, neuropeptides and hormones. Here, we provide an overview of the synaptotagmin family, and review the recent mouse genetic studies aimed at understanding the functions of synaptotagmins in neurotransmission and endocrine-hormone secretion...

  7. Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

    Directory of Open Access Journals (Sweden)

    Xiaohong Wang

    2014-05-01

    Full Text Available Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA. Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications.

  8. 21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pantothenate, calcium chloride double salt. 172.330 Section 172.330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN..., calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

  9. Calcium affects on vascular endpoints

    Directory of Open Access Journals (Sweden)

    Patel Vaishali B

    2012-03-01

    Full Text Available Abstract Calcium is one of the most abundant minerals in the body and its metabolism is one of the basic biologic processes in humans. Although historically linked primarily to bone structural development and maintenance, calcium is now recognized as a key component of many physiologic pathways necessary for optimum health including cardiovascular, neurological, endocrine, renal, and gastrointestinal systems. A recent meta-analysis published in August 2011 showed a potential increase in cardiovascular events related to calcium supplementation. The possible mechanism of action of this correlation has not been well elucidated. This topic has generated intense interest due to the widespread use of calcium supplements, particularly among the middle aged and elderly who are at the most risk from cardiac events. Prior studies did not control for potential confounding factors such as the use of statins, aspirin or other medications. These controversial results warrant additional well-designed studies to investigate the relationship between calcium supplementation and cardiovascular outcomes. The purpose of this review is to highlight the current literature in regards to calcium supplementation and cardiovascular health; and to identify areas of future research.

  10. Peculiarities of the electronic structure of calcium and strontium apatites

    Energy Technology Data Exchange (ETDEWEB)

    Shpak, A.P. [Institute of Metal Physics NAS of Ukraine, akad. Vernadskii Str. 36, Kiev 03142 (Ukraine); Karbovskii, V.L. [Institute of Metal Physics NAS of Ukraine, akad. Vernadskii Str. 36, Kiev 03142 (Ukraine)], E-mail: karb@imp.kiev.ua; Kurgan, N.A. [Institute of Metal Physics NAS of Ukraine, akad. Vernadskii Str. 36, Kiev 03142 (Ukraine)

    2007-05-15

    The comparison of the calculated data of the total density of electronic states for a crystal elementary cell (LMTO-calculation) and cluster-calculation XO{sub 4}{sup 3-} of a tetrahedron has shown practical concordance of the form and main features of curves that indicates the determining role of nanofragment structures XO{sub 4}{sup 3-} tetrahedron in formation of the main features of calcium apatites total density of states. It is confirmed, that the electronic structure of stochiometric apatites systems is low sensitive to anions type (which is located along c-axis of crystal), right up to its elimination, that practically can be revealed in lability of apatite's structure relative to its position. The symmetry of XO{sub 4}{sup 3-} anion oscillations in a crystal lattice of apatite is determined not only by the symmetry of its local environment but also appreciably by the nature of chemical bonds X-O inside anion. The greatest influence on tetrahedral sublattice in calcium apatite renders ion Cl{sup -}, and in strontium apatite ion OH{sup -}. The symmetry of tetrahedrons in strontium fluorapatite is higher comparing to hydroxy- and chlorapatite. The indirect interaction metal-metal is observed in metal sublattice. This interaction occurs mainly between atoms in Ca{sub (2)} positions with participation of oxygen hydroxyl group atoms. The channel of interaction Ca{sub (2)}-O{sub (3)}-Ca{sub (1)} through of oxygen atoms from PO{sub 4}{sup -} groups is observed thus less expressed. The interaction of ions Ca{sub (2)} with hydroxyl in hydroxyvanadate is much weaker, than in hydroxyapatite. It is shown, that in the formation of the L{sub {alpha}}-spectra form curve of calcium in calcium apatites the significant role is played by the nuclear effects and, as consequence, the participation of d-states of calcium in formation of bond is graded by their significant localization, most likely in an internal valley of effective potential.

  11. Prevention of recurrent calcium stones: diet versus drugs.

    Science.gov (United States)

    Jaeger, P

    1994-01-01

    Excessive intakes of meat protein, oxalate and potentially sodium, as well as insufficient intakes of vegetables fibers, calcium and fluid all lead to increased urinary crystallization. Renal stone disease, however, does not have to ensue. The underlying condition in a given patient is of paramount importance to allow 'bad eating habits' to lead to nephrolithiasis. Several of these underlying abnormalities have been detected so far from which we recently derived the powder keg and tinderbox theory. Most of the time, the dietary approach to nephrolithiasis allows recurrence of renal stone formation to be prevented. The pharmacological approach should be reserved for refractory cases.

  12. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  13. Clogging and Cementation Caused by Calcium or Iron Biogrouts

    Science.gov (United States)

    Ivanov, V.; Chu, J.; Naeimi, M.

    2012-12-01

    Chemical grouts are often used to reduce the hydraulic conductivity of soil for seepage control purposes. However, chemical grouts can be expensive and environmentally unfriendly. Therefore, two new biogrouts were tested for their bioclogging and biocementation properties. The first was calcium-based biogrout, which contained urease-producing bacteria, calcium chloride and urea for the crystallization of calcite due to enzymatic hydrolysis of urea. The second was iron-based biogrout, which consisted of urease-producing bacteria, ferric chelate, and urea for the precipitation of ferric hydroxide and carbonate due to enzymatic hydrolysis of urea. The permeability of sand (P, 10^-5 m/s), treated with calcium-based biogrout, linearly decreased as a function of the content of precipitated calcium (C, % w/w) according to the following equation: P = 5.1 - 4.0 C. Meanwhile, the permeability of sand treated with iron-based biogrout dropped to 2.7x10^-6 m/s at content of precipitated iron (F, % w/w) about 0.35 % w/w , by the equation: P = 5.1 - 14.6 F , and then slowly decreased to 1.4x10^-7 m/s at content of precipitated iron 1.8% w/w by the following equation: P = 0.36 - 0.23F. Both biogrouts have approximately same efficiency in the reduction of permeability of sand to low values. However, the mechanisms of bioclogging are probably different because the reduction of permeability by calcium-based biogrout was described by linear function of precipitated calcium but the reduction of permeability by iron-based biogrout showed two steps of the clogging. Different functions and mechanisms were related probably to the different type of precipitates. The images of biogrouted sand samples show that calcium-based biogrout produced white amorphous or crystallised calcium carbonate, while iron-based biogrout produced gel-like brown precipitate without visible crystals. The unconfined compressive strengths of the sand treated with different biogrouts (Y, kPa) increased by power

  14. Calcium: the molecular basis of calcium action in biology and medicine

    National Research Council Canada - National Science Library

    Pochet, Roland; Donato, Rosario

    2000-01-01

    ... of Calcium Calcium Signalling in Excitable Cells Ca2+ Release in Muscle Cells by N. Macrez and J. Mironneau Calcium Signalling in Neurons Exemplified by Rat Sympathetic Ganglion Cells by S.J. M...

  15. Biomineralization of nanoscale single crystal hydroxyapatite.

    Science.gov (United States)

    Omokanwaye, Tiffany; Wilson, Otto C; Gugssa, Ayelle; Anderson, Winston

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague-Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54nm and 0.23nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Crystal Crosslinked Gels for the Deposition of Inorganic Salts with Polyhedral Shapes

    Directory of Open Access Journals (Sweden)

    Yumi Mochizuki

    2018-02-01

    Full Text Available Biomineralization has been given a great deal of attention by materials chemists because of its low environmental load and sustainability. With the goal of synthesizing such processes, various methods have been developed, especially for inorganic salts of calcium. In this report, we focused on the deposition of inorganic salts, such as calcium carbonate and calcium phosphate using crystal crosslinked gels (CCG, which are prepared by crystal crosslinking of metal-organic frameworks (MOFs. Due to the crystalline nature of MOFs, CCGs intrinsically possess polyhedral shapes derived from the original MOF crystals. As the result of deposition, the obtained inorganic salts also exhibited a polyhedral shape derived from the CCG. The deposition mainly occurred near the surface of the CCG, and the amorphous nature of the deposited inorganic salts was also confirmed.

  17. Growth of dopamine crystals

    Energy Technology Data Exchange (ETDEWEB)

    Patil, Vidya, E-mail: vidya.patil@ruparel.edu; Patki, Mugdha, E-mail: mugdha.patki@ruparel.edu [D. G. Ruparel College, Senapati Bapat Marg, Mahim, Mumbai – 400 016 (India)

    2016-05-06

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  18. Crystals in Urine Test

    Science.gov (United States)

    ... crystals or specific types of crystals can become kidney stones . Kidney stones are hard, pebble-like substances that can get ... big as a pea, or even larger. While kidney stones rarely cause serious damage, they can be very ...

  19. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

    Thomsen, Louiza Bohn; Jörntell, Henrik; Midtgaard, Jens

    2010-01-01

    Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX....... Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon...... appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1 s...

  20. Crystallographic Analysis of Calcium-dependent Heparin Binding to Annexin A2

    Energy Technology Data Exchange (ETDEWEB)

    Shao,C.; Zhang, F.; Kemp, M.; Lindhardt, R.; Waisman, D.; Head, J.; Seaton, B.

    2006-01-01

    Annexin A2 and heparin bind to one another with high affinity and in a calcium-dependent manner, an interaction that may play a role in mediating fibrinolysis. In this study, three heparin-derived oligosaccharides of different lengths were co-crystallized with annexin A2 to elucidate the structural basis of the interaction. Crystal structures were obtained at high resolution for uncomplexed annexin A2 and three complexes of heparin oligosaccharides bound to annexin A2. The common heparin-binding site is situated at the convex face of domain IV of annexin A2. At this site, annexin A2 binds up to five sugar residues from the nonreducing end of the oligosaccharide. Unlike most heparin-binding consensus patterns, heparin binding at this site does not rely on arrays of basic residues; instead, main-chain and side-chain nitrogen atoms and two calcium ions play important roles in the binding. Especially significant is a novel calcium-binding site that forms upon heparin binding. Two sugar residues of the heparin derivatives provide oxygen ligands for this calcium ion. Comparison of all four structures shows that heparin binding does not elicit a significant conformational change in annexin A2. Finally, surface plasmon resonance measurements were made for binding interactions between annexin A2 and heparin polysaccharide in solution at pH 7.4 or 5.0. The combined data provide a clear basis for the calcium dependence of heparin binding to annexin A2.

  1. Ubiquitylation functions in the calcium carbonate biomineralization in the extracellular matrix.

    Science.gov (United States)

    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.

  2. Assessment of microarchitecture and crystal structure of hydroxyapatite in osteoporosis

    Directory of Open Access Journals (Sweden)

    Zairin Noor

    2016-02-01

    Full Text Available Osteoporosis is characterized by lower bone mineral density (BMD and microarchitectural degeneration, which tends to increase bone fragility and fracture risk. Bone microstructure depends on interactions between the mineral atoms, which may perform substitution or incorporation into bone crystals, and may dynamically take over the function of calcium or may become a complementary part. The mineral atoms may also become a composite in the hydroxyapatite crystals. The aim of this study was to find an association between the bone microstructure and hydoxyapatite crystal structure in osteoporosis, in comparison to normal bone. The subjects of this study were surgery patients at the Department of Orthopedics of Ulin General Hospital in Banjarmasin and other centers. Inclusion criteria consisted of the presence of fracture of trabecular bone, normal or osteoporotic BMD values, and no past history of chronic disease. Bone was obtained from fracture patients during surgery. The characteristics of the hydroxyapatite crystals were analyzed by X-ray diffraction (XRD and the microarchitecture by scanning electron microscopy (SEM. SEM showed degeneration of the microarchitecture of osteoporotic bone, in comparison with normal bone. On XRD there was a peak of hydoxyapatite crystals only and no other crystal phases. Diffraction patterns showed a larger crystal size in osteoporotic bone as compared to normal bone, indicating higher porosity. It may be concluded that there is a difference in crystal size and morphologic distribution of hydoxyapatite in osteoporotic bone, determining bone microarchitecture.

  3. Assessment of microarchitecture and crystal structure of hydroxyapatite in osteoporosis

    Directory of Open Access Journals (Sweden)

    Zairin Noor

    2011-04-01

    Full Text Available Osteoporosis is characterized by lower bone mineral density (BMD and microarchitectural degeneration, which tends to increase bone fragility and fracture risk. Bone microstructure depends on interactions between the mineral atoms, which may perform substitution or incorporation into bone crystals, and may dynamically take over the function of calcium or may become a complementary part. The mineral atoms may also become a composite in the hydroxyapatite crystals. The aim of this study was to find an association between the bone microstructure and hydoxyapatite crystal structure in osteoporosis, in comparison to normal bone. The subjects of this study were surgery patients at the Department of Orthopedics of Ulin General Hospital in Banjarmasin and other centers. Inclusion criteria consisted of the presence of fracture of trabecular bone, normal or osteoporotic BMD values, and no past history of chronic disease. Bone was obtained from fracture patients during surgery. The characteristics of the hydroxyapatite crystals were analyzed by X-ray diffraction (XRD and the microarchitecture by scanning electron microscopy (SEM. SEM showed degeneration of the microarchitecture of osteoporotic bone, in comparison with normal bone. On XRD there was a peak of hydoxyapatite crystals only and no other crystal phases. Diffraction patterns showed a larger crystal size in osteoporotic bone as compared to normal bone, indicating higher porosity. It may be concluded that there is a difference in crystal size and morphologic distribution of hydoxyapatite in osteoporotic bone, determining bone microarchitecture.

  4. Determination of thermodynamic parameters for complexation of calcium and magnesium with chondroitin sulfate isomers using isothermal titration calorimetry: Implications for calcium kidney-stone research

    Science.gov (United States)

    Rodgers, Allen L.; Jackson, Graham E.

    2017-04-01

    Chondroitin sulfate (CS) occurs in human urine. It has several potential binding sites for calcium and as such may play an inhibitory role in calcium oxalate and calcium phosphate (kidney stone disease by reducing the supersaturation (SS) and crystallization of these salts. Urinary magnesium is also a role player in determining speciation in stone forming processes. This study was undertaken to determine the thermodynamic parameters for binding of the disaccharide unit of two different CS isomers with calcium and magnesium. These included the binding constant K. Experiments were performed using an isothermal titration calorimeter (ITC) at 3 different pH levels in the physiological range in human urine. Data showed that interactions between the CS isomers and calcium and magnesium occur via one binding site, thought to be sulfate, and that log K values are 1.17-1.93 and 1.77-1.80 for these two metals respectively. Binding was significantly stronger in Mg-CS than in Ca-CS complexes and was found to be dependent on pH in the latter but not in the former. Furthermore, binding in Ca-CS complexes was dependent on the location of the sulfate binding site. This was not the case in the Mg-CS complexes. Interactions were shown to be entropy driven and enthalpy unfavourable. These findings can be used in computational modeling studies to predict the effects of the calcium and magnesium CS complexes on the speciation of calcium and the SS of calcium salts in real urine samples.

  5. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P parathyroid hormone levels (P animals (P = 0.057). However, mean arterial pressure was elevated (P animals fed low- compared with high-calcium diets (P parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  6. [Regulatory mechanism of calcium metabolism.

    Science.gov (United States)

    Ozono, Keiichi

    It is often difficult for terrestrial animals to take enough calcium. To maintain serum or extracellular calcium levels is very important for muscle and nerve function. Two major regulators to increase the serum calcium levels are parathyroid hormone(PTH)and vitamin D. PTH binds to the G protein coupling receptor, PTH1R, and increases intracellular cAMP levels. Impirement in the PTH signalling causes many diseases such as pseudohypoparathyroidism and acrodysostosis with hormone resistance. Vitamin D is activated to 1,25-dihydroxyvitamin D[1,25(OH)2D]by two steps of hydroxylation which occurs in the Liver and Kidney. Then, 1,25(OH)2D binds to vitamin D receptor(VDR), which works as a ligand-dependent transcription factor. Hypocalcemia and hypercalcemia are caused by various disorders including abnormal regulation of PTH and vitamin D production and their signal transduction.

  7. Calcium signaling and cell proliferation.

    Science.gov (United States)

    Pinto, Mauro Cunha Xavier; Kihara, Alexandre Hiroaki; Goulart, Vânia A M; Tonelli, Fernanda M P; Gomes, Katia N; Ulrich, Henning; Resende, Rodrigo R

    2015-11-01

    Cell proliferation is orchestrated through diverse proteins related to calcium (Ca(2+)) signaling inside the cell. Cellular Ca(2+) influx that occurs first by various mechanisms at the plasma membrane, is then followed by absorption of Ca(2+) ions by mitochondria and endoplasmic reticulum, and, finally, there is a connection of calcium stores to the nucleus. Experimental evidence indicates that the fluctuation of Ca(2+) from the endoplasmic reticulum provides a pivotal and physiological role for cell proliferation. Ca(2+) depletion in the endoplasmatic reticulum triggers Ca(2+) influx across the plasma membrane in an phenomenon called store-operated calcium entries (SOCEs). SOCE is activated through a complex interplay between a Ca(2+) sensor, denominated STIM, localized in the endoplasmic reticulum and a Ca(2+) channel at the cell membrane, denominated Orai. The interplay between STIM and Orai proteins with cell membrane receptors and their role in cell proliferation is discussed in this review. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Calcium regulation of muscle contraction.

    Science.gov (United States)

    Szent-Györgyi, A G

    1975-07-01

    Calcium triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin. Two different regulatory systems are found in different muscles. In actin-linked regulation troponin and tropomyosin regulate actin by blocking sites on actin required for complex formation with myosin; in myosin-linked regulation sites on myosin are blocked in the absence of calcium. The major features of actin control are as follows: there is a requirement for tropomyosin and for a troponin complex having three different subunits with different functions; the actin displays a cooperative behavior; and a movement of tropomyosin occurs controlled by the calcium binding on troponin. Myosin regulation is controlled by a regulatory subunit that can be dissociated in scallop myosin reversibly by removing divalent cations with EDTA. Myosin control can function with pure actin in the absence of tropomyosin. Calcium binding and regulation of molluscan myosins depend on the presence of regulatory light chains. It is proposed that the light chains function by sterically blocking myosin sites in the absence of calcium, and that the "off" state of myosin requires cooperation between the two myosin heads. Both myosin control and actin control are widely distributed in different organisms. Many invertebrates have muscles with both types of regulation. Actin control is absent in the muscles of molluscs and in several minor phyla that lack troponin. Myosin control is not found in striated vertebrate muscles and in the fast muscles of crustacean decapods, although regulatory light chains are present. While in vivo myosin control may not be excluded from vertebrate striated muscles, myosin control may be absent as a result of mutations of the myosin heavy chain.

  9. Biomolecular Modification of Inorganic Crystal Growth

    Energy Technology Data Exchange (ETDEWEB)

    De Yoreo, J J

    2007-04-27

    The fascinating shapes and hierarchical designs of biomineralized structures are an inspiration to materials scientists because of the potential they suggest for biomolecular control over materials synthesis. Conversely, the failure to prevent or limit tissue mineralization in the vascular, skeletal, and urinary systems is a common source of disease. Understanding the mechanisms by which organisms direct or limit crystallization has long been a central challenge to the biomineralization community. One prevailing view is that mineral-associated macromolecules are responsible for either inhibiting crystallization or initiating and stabilizing non-equilibrium crystal polymorphs and morphologies through interactions between anionic moieties and cations in solution or at mineralizing surfaces. In particular, biomolecules that present carboxyl groups to the growing crystal have been implicated as primary modulators of growth. Here we review the results from a combination of in situ atomic force microscopy (AFM) and molecular modeling (MM) studies to investigate the effect of specific interactions between carboxylate-rich biomolecules and atomic steps on crystal surfaces during the growth of carbonates, oxalates and phosphates of calcium. Specifically, we how the growth kinetics and morphology depend on the concentration of additives that include citrate, simple amino acids, synthetic Asp-rich polypeptides, and naturally occurring Asp-rich proteins found in both functional and pathological mineral tissues. The results reveal a consistent picture of shape modification in which stereochemical matching of modifiers to specific atomic steps drives shape modification. Inhibition and other changes in growth kinetics are shown to be due to a range of mechanisms that depend on chemistry and molecular size. Some effects are well described by classic crystal growth theories, but others, such as step acceleration due to peptide charge and hydrophylicity, were previously unrealized

  10. Can total cardiac calcium predict the coronary calcium score?

    Science.gov (United States)

    Pressman, Gregg S; Crudu, Vitalie; Parameswaran-Chandrika, Anoop; Romero-Corral, Abel; Purushottam, Bhaskar; Figueredo, Vincent M

    2011-01-21

    Mitral annular calcification (MAC) shares the same risk factors as atherosclerosis and is associated with coronary artery disease as well as cardiovascular events. However, sensitivity and positive predictive value are low. We hypothesized that a global echocardiographic calcium score would better predict coronary atherosclerotic burden, as assessed by coronary artery calcium score (CAC), than MAC alone. An echocardiographic score was devised to measure global cardiac calcification in a semi-quantitative manner; this included calcification in the aortic valve and root, the mitral valve and annulus, and the sub-mitral apparatus. This score, and a simplified version, were compared with a similar calcification score by CT scan, as well as the CAC. There was a good correlation between the two global calcification scores; the echocardiographic score also correlated with CAC. Using CAC >400 as a measure of severe coronary atherosclerosis, an echocardiographic score ≥5 had a positive predictive value of 60%. Importantly, the simplified score performed equally well (≥3 had a positive predictive value of 62%). Global cardiac calcification, assessed by CT scan or echocardiography, correlates with the extent of coronary calcium. A semi-quantitative calcium score can be easily applied during routine echocardiographic interpretation and can alert the reader to the possibility of severe coronary atherosclerosis. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  11. Calcium ferrite formation from the thermolysis of calcium tris (maleato)

    Indian Academy of Sciences (India)

    stoichiometric quantities of aqueous solutions of calcium maleate, iron(III) maleate and maleic acid. The reaction mixture was concentrated on a water bath until a brown coloured product formed after the addition of excess of acetone. The complex was vacuum dried and its identity was established by chemical analysis.

  12. Calcium ferrite formation from the thermolysis of calcium tris ...

    Indian Academy of Sciences (India)

    Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to 900°C and ferrite formation. Three consecutive decomposition steps leading to the formation of -Fe2O3 and calcium carbonate have been observed at various stages of ...

  13. Calcium carbonates: induced biomineralization with controlled macromorphology

    Science.gov (United States)

    Meier, Aileen; Kastner, Anne; Harries, Dennis; Wierzbicka-Wieczorek, Maria; Majzlan, Juraj; Büchel, Georg; Kothe, Erika

    2017-11-01

    Biomineralization of (magnesium) calcite and vaterite by bacterial isolates has been known for quite some time. However, the extracellular precipitation has hardly ever been linked to different morphologies of the minerals that are observed. Here, isolates from limestone-associated groundwater, rock and soil were shown to form calcite, magnesium calcite or vaterite. More than 92 % of isolates were indeed able to form carbonates, while abiotic controls failed to form minerals. The crystal morphologies varied, including rhombohedra, prisms and pyramid-like macromorphologies. Different conditions like varying temperature, pH or media components, but also cocultivation to test for collaborative effects of sympatric bacteria, were used to differentiate between mechanisms of calcium carbonate formation. Single crystallites were cemented with bacterial cells; these may have served as nucleation sites by providing a basic pH at short distance from the cells. A calculation of potential calcite formation of up to 2 g L-1 of solution made it possible to link the microbial activity to geological processes.

  14. Photonic crystal light source

    Science.gov (United States)

    Fleming, James G [Albuquerque, NM; Lin, Shawn-Yu [Albuquerque, NM; Bur, James A [Corrales, NM

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  15. Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

    Directory of Open Access Journals (Sweden)

    Dmitry eSamigullin

    2015-01-01

    Full Text Available At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 рА and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 µM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

  16. Amorphous calcium phosphate and its application in dentistry

    Directory of Open Access Journals (Sweden)

    Sun Wei-bin

    2011-07-01

    Full Text Available Abstract Amorphous Calcium Phosphate (ACP is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree 2 theta, and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystalline. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo. Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures. This review provides an overview of the development, structure, chemical composition, morphological characterization, phase transformation and biomedical application of ACP in dentistry.

  17. Calcium release from experimental dental materials.

    Science.gov (United States)

    Okulus, Zuzanna; Buchwald, Tomasz; Voelkel, Adam

    2016-11-01

    The calcium release from calcium phosphate-containing experimental dental restorative materials was examined. The possible correlation of ion release with initial calcium content, solubility and degree of curing (degree of conversion) of examined materials was also investigated. Calcium release was measured with the use of an ion-selective electrode in an aqueous solution. Solubility was established by the weighing method. Raman spectroscopy was applied for the determination of the degree of conversion, while initial calcium content was examined with the use of energy-dispersive spectroscopy. For examined materials, the amount of calcium released was found to be positively correlated with solubility and initial calcium content. It was also found that the degree of conversion does not affect the ability of these experimental composites to release calcium ions. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Familial hypocalciuric hypercalcemia and calcium sensing receptor

    DEFF Research Database (Denmark)

    Mrgan, Monija; Nielsen, Sanne; Brixen, Kim

    2014-01-01

    Familial hypocalciuric hypercalcemia (FHH) is a lifelong, benign autosomal dominant disease characterized by hypercalcemia, normal to increased parathyroid hormone level, and a relatively low renal calcium excretion. Inactivation of the calcium-sensing receptor in heterozygous patients results in...

  19. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... Bone Health Featured Resource Find an Endocrinologist Search Vitamin D, Calcium, and Bone Health March 2012 Download ... also helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin ...

  20. High-pressure stability and compressibility of APO[subscript 4] (A=La, Nd, Eu, Gd, Er, and Y) orthophosphates: An x-ray diffraction study using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lacomba-Perales, R.; Errandonea, D.; Meng, Y.; Bettinelli, M. (Verona); (Valencia); (CIW)

    2010-03-16

    Room-temperature angle-dispersive x-ray diffraction measurements on zircon-type YPO{sub 4} and ErPO{sub 4}, and monazite-type GdPO{sub 4}, EuPO{sub 4}, NdPO{sub 4}, and LaPO{sub 4} were performed in a diamond-anvil cell up to 30 GPa using neon as pressure-transmitting medium. In the zircon-structured oxides we found evidence of a reversible pressure-induced structural phase transformation from zircon to a monazite-type structure. The onset of the transition is at 19.7 GPa in YPO{sub 4} and 17.3 GPa in ErPO{sub 4}. In LaPO{sub 4} a nonreversible transition is found at 26.1 GPa and a barite-type structure is proposed for the high-pressure phase. For the other three monazites studied, their structures were found to be stable up to 30 GPa. Evidence for additional phase transitions or chemical decomposition of the materials was not found in the experiments. The equations of state and axial compressibility for the different phases are also determined. In particular, we found that in a given compound the monazite structure is less compressible than the zircon structure. This fact is attributed to the higher packing efficiency of monazite versus zircon. The differential bond compressibility of different polyhedra is also reported and related to the anisotropic compressibility of both structures. Finally, the sequence of structural transitions and compressibilities are discussed in comparison with other orthophosphates.

  1. 21 CFR 184.1229 - Calcium stearate.

    Science.gov (United States)

    2010-04-01

    ... Specific Substances Affirmed as GRAS § 184.1229 Calcium stearate. (a) Calcium stearate (Ca(C17H35COO)2, CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium stearate. 184.1229 Section 184.1229 Food...

  2. Bioactive and Hemocompatible Calcium Sulphoaluminate Cement

    OpenAIRE

    Acuña-Gutiérrez, Iván Omar; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Cortés-Hernández, Dora Alicia; Saldívar-Ramírez, Mirna María Guadalupe; Reséndiz-Hernández, Perla Janet; Zugasti-Cruz, Alejandro

    2015-01-01

    Calcium sulphoaluminate cement (CSAC) is an attractive candidate for biomedical applications due to its appropriate mechanical properties and high calcium content. In vitro bioactivity and hemocompatibility of calcium sulphoaluminate cement were assessed. The cement was prepared from a mixture of calcium sulphoaluminate (CSA) clinker, gypsum and water. Cement samples were immersed in a simulated body fluid (SBF) at 37 °C for different periods of time (7, 14 and 21 days). The analyses of these...

  3. Calcium Balance in Chronic Kidney Disease

    OpenAIRE

    Hill Gallant, Kathleen M.; Spiegel, David M.

    2017-01-01

    Purpose of Review The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balan...

  4. Calcium Balance in Chronic Kidney Disease.

    Science.gov (United States)

    Hill Gallant, Kathleen M; Spiegel, David M

    2017-06-01

    The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

  5. Electrochemical Induced Calcium Phosphate Precipitation

    NARCIS (Netherlands)

    Lei, Yang; Song, Bingnan; Weijden, van der Renata D.; Saakes, M.; Buisman, Cees J.N.

    2017-01-01

    Phosphorus (P) is an essential nutrient for living organisms and cannot be replaced or substituted. In this paper, we present a simple yet efficient membrane free electrochemical system for P removal and recovery as calcium phosphate (CaP). This method relies on in situ formation of hydroxide

  6. 21 CFR 582.7187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is generally...

  7. Abnormalities of serum calcium and magnesium

    Science.gov (United States)

    Neonatal hypocalcemia is defined as a total serum calcium concentration of <7 mg/dL or an ionized calcium concentration of <4 mg/dL (1mmol/L). In very low birth weight (VLBW) infants, ionized calcium values of 0.8 to 1 mmol/L are common and not usually associated with clinical symptoms. In larger in...

  8. Modularized study of human calcium signalling pathway

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    When there is an extracellular change, cells get the message either by introduction of calcium ions into ... as it precipitates phosphate, the established energy currency of cells. Prolonged high intracellular calcium ... trigger proteins upon binding with free calcium ion(s) change their confirmation to modulate enzymes and ion ...

  9. 21 CFR 582.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL...

  10. 21 CFR 582.5191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.5191 Section 582.5191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL...

  11. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Activation of receptors coupled to the phospholipase C/IP3 signalling pathway results in a rapid release of calcium from its intracellular stores, eventually leading to depletion of these stores. Calcium store depletion triggers an influx of extracellular calcium across the plasma membrane, a mechanism known as the ...

  12. Mitochondrial Calcium Sparkles Light Up Astrocytes.

    Science.gov (United States)

    MacVicar, Brian A; Ko, Rebecca W Y

    2017-02-27

    Discrete calcium signals in the fine processes of astrocytes are a recent discovery and a new mystery. In a recent issue of Neuron, Agarwal et al. (2017) report that calcium efflux from mitochondria during brief openings of the mitochondrial permeability transition pore (mPTP) contribute to calcium microdomains. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  13. 21 CFR 182.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium phosphate. 182.1217 Section 182.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b...

  14. 21 CFR 582.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.1217 Section 582.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b...

  15. ORIGINAL ARTICLES Calcium supplementation to prevent pre ...

    African Journals Online (AJOL)

    ORIGINAL ARTICLES. Calcium supplementation to prevent pre-eclampsia - a systematic review. G J Hofmeyr, A Roodt, A N Atallah, L Duley. Background. Calcium supplementation during pregnancy may prevent high blood pressure and preterm labour. Objective. To assess the effects of calcium supplementation.

  16. Influence of precursor solution parameters on chemical properties of calcium phosphate coatings prepared using Electrostatic Spray Deposition (ESD).

    NARCIS (Netherlands)

    Leeuwenburgh, S.C.G.; Wolke, J.G.C.; Schoonman, J.; Jansen, J.A.

    2004-01-01

    A novel coating technique, referred to as Electrostatic Spray Deposition (ESD), was used to deposit calcium phosphate (CaP) coatings with a variety of chemical properties. The relationship between the composition of the precursor solutions and the crystal and molecular structure of the deposited

  17. Differentiation of Calcium Carbonate Polymorphs by Surface Analysis Techniques – An XPS and TOF-SIMS study

    Science.gov (United States)

    Ni, Ming; Ratner, Buddy D.

    2013-01-01

    Calcium carbonate has evoked interest owing to its use as a biomaterial, and for its potential in biomineralization. Three polymorphs of calcium carbonate, i.e. calcite, aragonite, and vaterite were synthesized. Three conventional bulk analysis techniques, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and SEM, were used to confirm the crystal phase of each polymorphic calcium carbonate. Two surface analysis techniques, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS), were used to differentiate the surfaces of these three polymorphs of calcium carbonate. XPS results clearly demonstrate that the surfaces of these three polymorphs are different as seen in the Ca(2p) and O(1s) core-level spectra. The different atomic arrangement in the crystal lattice, which provides for a different chemical environment, can explain this surface difference. Principal component analysis (PCA) was used to analyze the TOF-SIMS data. Three polymorphs of calcium carbonate cluster into three different groups by PCA scores. This suggests that surface analysis techniques are as powerful as conventional bulk analysis to discriminate calcium carbonate polymorphs. PMID:25031482

  18. Morphological Investigation of Calcium Carbonate during Ammonification-Carbonization Process of Low Concentration Calcium Solution

    OpenAIRE

    Huaigang Cheng; Xiaoxi Zhang; Huiping Song

    2014-01-01

    Ultrafine calcium carbonate is a widely used cheap additive. The research is conducted in low degree supersaturation solution in order to study the polymorphic phases’ change and its factors of the calcium carbonate precipitate in the ammonification-carbonization process of the solution with calcium. Fine particles of calcium carbonate are made in the solution containing 0.015 mol/L of Ca2+. Over 98% of the calcium carbonate precipitate without ammonification resembles the morphology of calci...

  19. Structural Changes in the Lectin Domain of CD23, the Low-Affinity IgE Receptor, upon Calcium Binding

    Energy Technology Data Exchange (ETDEWEB)

    Wurzburg, Beth A.; Tarchevskaya, Svetlana S.; Jardetzky, Theodore S. (NWU)

    2010-03-08

    CD23, the low-affinity receptor for IgE (Fc{var_epsilon}RII), regulates IgE synthesis and also mediates IgE-dependent antigen transport and processing. CD23 is a unique Fc receptor belonging to the C-type lectin-like domain superfamily and binds IgE in an unusual, non-lectin-like manner, requiring calcium but not carbohydrate. We have solved the high-resolution crystal structures of the human CD23 lectin domain in the presence and absence of Ca{sup 2+}. The crystal structures differ significantly from a previously determined NMR structure and show that calcium binding occurs at the principal binding site, but not at an auxiliary site that appears to be absent in human CD23. Conformational differences between the apo and Ca{sup 2+} bound structures suggest how IgE-Fc binding can be both calcium-dependent and carbohydrate-independent.

  20. Calcium pyrophosphate dihydrate deposition disease (CPPD/Pseudogout of the temporomandibular joint – FNA findings and microanalysis

    Directory of Open Access Journals (Sweden)

    Naqvi Asghar H

    2008-04-01

    Full Text Available Abstract We report a case of a Calcium pyrophosphate dihydrate deposition disease (CPPD presenting as a mass in the parotid and temporomandibular joint (TMJ that simulated a parotid tumor. A 35 year-old man presented with pain in the left ear area. A CT Scan of the area showed a large, calcified mass surrounding the left condylar head, and extending into the infratemporal fossa. FNA of the mass showed birefringent crystals, most of which were rhomboid with occasional ones being needle shaped, embedded in an amorphous pink substance. Scanning electron microscopy (SEM with energy dispersive x-ray spectroscopy (EDS of these crystals showed peaks corresponding to calcium and phosphorus. SEM/EDS is a rapid method of diagnosing calcium pyrophosphate dihydrate deposition disease (CPPD and an alternative to more commonly used method of special staining of cell block sections coupled with polarizing microscopy.

  1. Mammary-Specific Ablation of the Calcium-Sensing Receptor During Lactation Alters Maternal Calcium Metabolism, Milk Calcium Transport, and Neonatal Calcium Accrual

    Science.gov (United States)

    Mamillapalli, Ramanaiah; VanHouten, Joshua; Dann, Pamela; Bikle, Daniel; Chang, Wenhan; Brown, Edward

    2013-01-01

    To meet the demands for milk calcium, the lactating mother adjusts systemic calcium and bone metabolism by increasing dietary calcium intake, increasing bone resorption, and reducing renal calcium excretion. As part of this adaptation, the lactating mammary gland secretes PTHrP into the maternal circulation to increase bone turnover and mobilize skeletal calcium stores. Previous data have suggested that, during lactation, the breast relies on the calcium-sensing receptor (CaSR) to coordinate PTHrP secretion and milk calcium transport with calcium availability. To test this idea genetically, we bred BLG-Cre mice with CaSR-floxed mice to ablate the CaSR specifically from mammary epithelial cells only at the onset of lactation (CaSR-cKO mice). Loss of the CaSR in the lactating mammary gland did not disrupt alveolar differentiation or milk production. However, it did increase the secretion of PTHrP into milk and decreased the transport of calcium from the circulation into milk. CaSR-cKO mice did not show accelerated bone resorption, but they did have a decrease in bone formation. Loss of the mammary gland CaSR resulted in hypercalcemia, decreased PTH secretion, and increased renal calcium excretion in lactating mothers. Finally, loss of the mammary gland CaSR resulted in decreased calcium accrual by suckling neonates, likely due to the combination of increased milk PTHrP and decreased milk calcium. These results demonstrate that the mammary gland CaSR coordinates maternal bone and calcium metabolism, calcium transport into milk, and neonatal calcium accrual during lactation. PMID:23782944

  2. Crystallization of Macromolecules

    Science.gov (United States)

    Friedmann, David; Messick, Troy; Marmorstein, Ronen

    2014-01-01

    X-ray crystallography has evolved into a very powerful tool to determine the three-dimensional structure of macromolecules and macromolecular complexes. The major bottleneck in structure determination by X-ray crystallography is the preparation of suitable crystalline samples. This unit outlines steps for the crystallization of a macromolecule, starting with a purified, homogeneous sample. The first protocols describe preparation of the macromolecular sample (i.e., proteins, nucleic acids, and macromolecular complexes). The preparation and assessment of crystallization trials is then described, along with a protocol for confirming whether the crystals obtained are composed of macromolecule as opposed to a crystallization reagent . Next, the optimization of crystallization conditions is presented. Finally, protocols that facilitate the growth of larger crystals through seeding are described. PMID:22045560

  3. Electronic crystal growth

    Science.gov (United States)

    Sato, T.; Miyagawa, K.; Kanoda, K.

    2017-09-01

    Interacting atoms or molecules condense into liquid, and, when cooled further, they form a crystal. The time evolution of the atomic or molecular ordering has been widely studied as a nonequilibrium emergence of order from a supercooled liquid or a glass. Interacting electrons in a variety of correlated electron systems also form crystals, but observing the time evolution of electronic crystallization has been experimentally challenging. Here, working with an organic conductor exhibiting a supercooled charge liquid or charge glass as a metastable state, we observed electronic crystal growth through resistivity and nuclear magnetic resonance measurements. The temperature profile of the crystal growth is similar to those observed in classical systems and reveals two distinct regimes for the mechanism of electronic crystallization.

  4. Active Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Ek, Sara

    due to photonic crystal dispersion. The observations are explained by the enhancement of net gain by light slow down. Another application based on active photonic crystal waveguides is micro lasers. Measurements on quantum dot micro laser cavities with different mirror configurations and photonic......This thesis deals with the fabrication and characterization of active photonic crystal waveguides, realized in III-V semiconductor material with embedded active layers. The platform offering active photonic crystal waveguides has many potential applications. One of these is a compact photonic...... crystal semiconductor optical amplier. As a step towards such a component, photonic crystal waveguides with a single quantum well, 10 quantum wells and three layers of quantum dots are fabricated and characterized. An experimental study of the amplied spontaneous emission and a implied transmission...

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

    Science.gov (United States)

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

    2004-11-01

    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 skeletal material, they probably all use this same mechanism. Deposition of transient amorphous phases as a strategy for producing single crystals with complex morphology may have interesting implications for the development of sophisticated materials.

  6. Kinetics and mechanisms of the transformation of precipitated amorphous calcium phosphate with a Ca/P ratio of 1:1 to calcium pyrophosphates

    Science.gov (United States)

    Zyman, Zoltan; Goncharenko, Anton; Rokhmistrov, Dmytro

    2017-11-01

    The kinetics and mechanisms of crystallization, phase transformation and grain growth in amorphous calcium pyrophosphate (ACPP) derived from the fast nitrate synthesis were studied at 600-800 °C. The high-temperature calcium pyrophosphate α-CPP crystallized as the major and metastable phase (α/-CPP), and some stable β-CPP polymorph also formed. The activation energies were determined with 80 kJ/mol for α/-CPP grain growth, as well as with 525, 190 and 180 kJ/mol for β-CPP nucleation, formation and grain growth during α/-CPP to β-CPP transformation under isothermal annealing, respectively. The transformation processes were mainly proceeded by surface diffusion and additional volume diffusion as the temperature was increased. The metastable α/-CPP crystallization was associated with the Ostwald's step rule. The formation of two polymorphs from the same ACPP was assumed to occur from two different short-range order units formed in ACPP before the onset of crystallization.

  7. Computational study of a calcium release-activated calcium channel

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-05-01

    The naturally occurring proteins that form hole in membrane are commonly known as ion channels. They play multiple roles in many important biological processes. Deletion or alteration of these channels often leads to serious problems in the physiological processes as it controls the flow of ions through it. The proper maintenance of the flow of ions, in turn, is required for normal health. Here we have investigated the behavior of a calcium release-activated calcium ion channel with pdb entry 4HKR in Drosophila Melanogaster. The equilibrium energy as well as molecular dynamics simulation is performed first. The protein is subjected to molecular dynamics simulation to find their energy minimized value. Simulation of the protein in the environment of water and ions has given us important results too. The solvation energy is also found using Charmm potential.

  8. Single Crystal Faceplate Evaluation

    Science.gov (United States)

    1993-10-25

    7]. Much the research at Allied-Signal, Inc. in garnet layer growth has been involved with the kinetics of crystallization of garnet from LPE melts...acceptable resolution and light output characteristics. Single crystal faceplates being evaluated are composed of yttrium aluminum garnet (YAG) with an...1.1 Single Crystal Faceplate Developments Allied Signal, Inc. has done extensive development work in epitaxial layering of yttrium aluminum garnet (YAG

  9. The Calcium Wave of Vegetable Cells

    Directory of Open Access Journals (Sweden)

    TD. Geydan

    2007-08-01

    Full Text Available Calcium is an essential nutrient for plants; it is involved in developmental processes and in responses to biotic and abiotic factors. Several signals that modify the calcium concentration in the cytoplasm, endoplasmic reticulum, nucleus and/or plastids have been observed. These changes in the calcium concentration in the cell interior are rapidly returned to basal levels, in the meantime, innumerable and complex signaling cascades. This note exposes the mechanisms of calcium transport through the cell membranes of the entrance of calcium in the plant cells.

  10. Calcium pyrophosphate dihydrate deposition in the trochanteric hip bursa presenting as acute hip pain.

    Science.gov (United States)

    Salar, Omer; Mushtaq, Fizza; Ahmed, Mushtaq

    2012-07-10

    Acute hip pain is a common reason for attendance to hospital. Immediate diagnoses include occult fractures, infectious and non-infectious inflammatory processes such as gout and pseudogout. Calcium pyrophosphate deposition disease (CPDD) is a rheumatological syndrome affecting articular cartilage and/or synovial fluid. It can occur as a clinical presentation (pseudogout) where calcium pyrophosphate dihydrate (CPPD) crystals are deposited within the joint space or radiographically, as chondrocalcinosis (CC), where CPPD crystals are deposited onto articular cartilages. Extraarticular manifestations of CPDD are rare. The authors report a case of CPPD deposition in the trochanteric bursa of a 35-year-old woman presenting as acute hip pain. The patient was treated successfully during arthroscopy with removal of the deposits and excision of the bursa. The patient remains well at 6 month follow-up.

  11. Circular patterns of calcium oxalate monohydrate induced by defective Langmuir-Blodgett film on quartz substrates

    Energy Technology Data Exchange (ETDEWEB)

    He Jieyu [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Ouyang Jianming [Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China); Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632 (China)], E-mail: toyjm@jnu.edu.cn

    2009-01-01

    The defective Langmuir-Blodgett (LB) film of dipalmitoylphosphatidylcholine (DPPC) on quartz injured by potassium oxalate (K{sub 2}C{sub 2}O{sub 4}) was used as a model system to induce growth of calcium oxalate crystals. Atomic force microscopy (AFM) indicated that circular defective domains with a diameter of 1-200 {mu}m existed in the LB film. Scanning electron microscopy (SEM) showed circular patterns of aggregated calcium oxalate monohydrate (COM) crystallites were induced by these defective domains. It was ascribed to that the interaction between the negatively-charged oxalate ions and the phosphatidyl groups in DPPC headgroups makes the phospholipid molecules rearranged and exist in an out-of-order state in the LB film, especially at the boundaries of liquid-condensed (LC)/liquid-expanded (LE) phases, which provide much more nucleating sites for COM crystals.

  12. Analysis of liquid crystal properties for photonic crystal fiber devices

    DEFF Research Database (Denmark)

    Weirich, Johannes; Lægsgaard, Jesper; Wei, Lei

    2009-01-01

    We analyze the bandgap structure of Liquid Crystal infiltrated Photonic Crystal Fibers depending on the parameters of the Liquid Crystals by means of finite element simulations. For a biased Liquid Crystal Photonic Crystal Fiber, we show how the tunability of the bandgap position depends...

  13. Crystallization Formulation Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Crystallization Formulation Lab fills a critical need in the process development and optimization of current and new explosives and energetic formulations. The...

  14. A crystal barrel

    CERN Multimedia

    2007-01-01

    The production of crystals for the barrel of the CMS electromagnetic calorimeter has been completed. This is an important milestone for the experiment, which received the last of its 62,960 crystals on 9 March. The members of the team responsible for the crystal acceptance testing at CERN display the last crystal for the CMS electromagnetic calorimeter barrel. From left to right: Igor Tarasov, Etiennette Auffray and Hervé Cornet.One of the six machines specially developed to measure 67 different parameters on each crystal. Igor Tarasov is seen inserting the last batch of crystals into the machine. The last of the 62,960 CMS barrel crystals arrived at CERN on 9 March. Once removed from its polystyrene protection, this delicate crystal, like thousands of its predecessors, will be inserted into the last of the 36 supermodules of the barrel electromagnetic calorimeter in a few days' time. This marks the end of an important chapter in an almost 15-year-long journey by the CMS crystals team, some of whose member...

  15. Automation in biological crystallization.

    Science.gov (United States)

    Stewart, Patrick Shaw; Mueller-Dieckmann, Jochen

    2014-06-01

    Crystallization remains the bottleneck in the crystallographic process leading from a gene to a three-dimensional model of the encoded protein or RNA. Automation of the individual steps of a crystallization experiment, from the preparation of crystallization cocktails for initial or optimization screens to the imaging of the experiments, has been the response to address this issue. Today, large high-throughput crystallization facilities, many of them open to the general user community, are capable of setting up thousands of crystallization trials per day. It is thus possible to test multiple constructs of each target for their ability to form crystals on a production-line basis. This has improved success rates and made crystallization much more convenient. High-throughput crystallization, however, cannot relieve users of the task of producing samples of high quality. Moreover, the time gained from eliminating manual preparations must now be invested in the careful evaluation of the increased number of experiments. The latter requires a sophisticated data and laboratory information-management system. A review of the current state of automation at the individual steps of crystallization with specific attention to the automation of optimization is given.

  16. Tunable plasmonic crystal

    Science.gov (United States)

    Dyer, Gregory Conrad; Shaner, Eric A.; Reno, John L.; Aizin, Gregory

    2015-08-11

    A tunable plasmonic crystal comprises several periods in a two-dimensional electron or hole gas plasmonic medium that is both extremely subwavelength (.about..lamda./100) and tunable through the application of voltages to metal electrodes. Tuning of the plasmonic crystal band edges can be realized in materials such as semiconductors and graphene to actively control the plasmonic crystal dispersion in the terahertz and infrared spectral regions. The tunable plasmonic crystal provides a useful degree of freedom for applications in slow light devices, voltage-tunable waveguides, filters, ultra-sensitive direct and heterodyne THz detectors, and THz oscillators.

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

    Science.gov (United States)

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

    2015-06-01

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

  18. Constant-distance mode scanning potentiometry. 1. Visualization of calcium carbonate dissolution in aqueous solution.

    Science.gov (United States)

    Etienne, Mathieu; Schulte, Albert; Mann, Stefan; Jordan, Guntram; Dietzel, Irmgard D; Schuhmann, Wolfgang

    2004-07-01

    Constant-distance mode scanning potentiometry was established by integrating potentiometric microsensors as ion-selective scanning probes into a SECM setup that was equipped with a piezoelectric shear force-based tip-to-sample distance control. The combination of specially designed micrometer-sized potentiometric tips with an advanced system for tip positioning allowed simultaneous acquisition of both topographic and potentiometric information at solid/liquid interfaces with high spatial resolution. The performance of the approach was evaluated by applying Ca(2+)-selective constant-distance mode potentiometry to monitor the dissolution of calcium carbonate occurring either at the (104) surface of calcite crystals or in proximity to the more complex surface of cross sections of a calcium carbonate shell of Mya arenaria exposed to slightly acidic aqueous solutions. Micrometer-scale heterogeneities in the apparent calcium activity profiles have successfully been resolved for both samples.

  19. Effect of Manganese on the Formation Mechanisms of Silico-Ferrite of Calcium and Aluminum (SFCA)

    Science.gov (United States)

    Xia, Leige; Li, Xinyu; Zhang, Jianliang; Yao, Chaoquan; Guo, Jian; Zhang, Chao

    In this research, analytical reagents were used for the sintering experiments. And the sinters were using X-ray diffraction, scanning electron microscope and mineralogical microscope analysis to study the effect mechanism of manganese on the silico-ferrite of calcium and aluminum (SFCA) bonding phase formation during the sintering process. The results indicated that the increasing content of manganese would greatly reduce the content of SFCA, and promote the formation of calcium aluminum silicate and the amount of pores and cracks. The existence of manganese inhibited the silicon form into the SFCA and a great deal of Fe2O3 was participated in the crystal transition to Fe3O4. When the ratio of the added manganese was less than 3% in the mixing, the calcium ferrite was in substantially interleaving corrosion with hematite and magnetite. Both the porosity and silicate glass phase content were low simultaneously, which contributed to the sintering production.

  20. Nanoscale observations of the effect of citrate on calcium oxalate precipitation on calcite surfaces.

    Science.gov (United States)

    Burgos-Cara, Alejandro; Ruiz-Agudo, Encarnacion; Putnis, Christine V.

    2016-04-01

    Calcium oxalate (CaC2O4ṡxH2O) minerals are naturally occurring minerals found in fossils, plants, kidney stones and is a by-product in some processes such as paper, food and beverage production [1,2]. In particular, calcium oxalate monohydrate phase (COM) also known as whewellite (CaC2O4ṡH2O), is the most frequently reported mineral phase found in urinary and kidney stones together with phosphates. Organic additives are well known to play a key role in the formation of minerals in both biotic and abiotic systems, either facilitating their precipitation or hindering it. In this regard, recent studies have provided direct evidence demonstrating that citrate species could enhance dissolution of COM and inhibit their precipitation. [3,4] The present work aims at evauate the influence of pH, citrate and oxalic acid concentrations in calcium oxalate precipitation on calcite surfaces (Island Spar, Chihuahua, Mexico) through in-situ nanoscale observation using in situ atomic force microscopy (AFM, Multimode, Bruker) in flow-through experiments. Changes in calcium oxalate morphologies and precipitated phases were observed, as well as the inhibitory effect of citrate on calcium oxalate precipitation, which also lead to stabilization an the amorphous calcium oxalate phase. [1] K.D. Demadis, M. Öner, Inhibitory effects of "green"additives on the crystal growth of sparingly soluble salts, in: J.T. Pearlman (Ed.), Green Chemistry Research Trends, Nova Science Publishers Inc., New York, 2009, pp. 265-287. [2] M. Masár, M. Zuborová, D. Kaniansky, B. Stanislawski, Determination of oxalate in beer by zone electrophoresis on a chip with conductivity detection, J. Sep. Sci. 26 (2003) 647-652. [3] Chutipongtanate S, Chaiyarit S, Thongboonkerd V. Citrate, not phosphate, can dissolve calcium oxalate monohydrate crystals and detach these crystals from renal tubular cells. Eur J Pharmacol 2012;689:219-25. [4] Weaver ML, Qiu SR, Hoyer JR, Casey WH, Nancollas GH, De Yoreo JJ

  1. Calcium Intake in the Moroccan Elderly

    Directory of Open Access Journals (Sweden)

    Sebbar El-houcine

    2017-08-01

    Full Text Available Introduction: Calcium intakes of elderly people are often below the recommendations which are 1200 mg/day. The advancing age may be accompanied by a loss of capacity to absorb additional calcium in case of deficiency. The aim of our work is to evaluate the calcium intake in the Moroccan elderly. Methods: The version translated into Arabic dialect Fardellone questionnaire is tested on a sample of 159 subjects aged over 60 years. Results: The study population includes 87 women (55%, 72 men (45%. The mean calcium intake was respectively 3078 mg by week (that means 440 mg/day. The assessment of calcium intake showed a deficiency and the average consumption of calcium per day is significantly lower than the recommended daily amount for this population. The comparison of both gender found a deficit higher among women than among men. Conclusion: Evaluation of the calcium intake is an essential tool for better management of metabolic bone diseases.

  2. Calcium Impact on Milk Gels Formation

    DEFF Research Database (Denmark)

    Koutina, Glykeria

    Calcium is one of the several elements that can be found in milk distributed between the micellar and the serum milk phase. Calcium is important from a nutritional point of view, but its contribution to the functional and structural properties of dairy products has only recently been...... acknowledgement. The presence of calcium in a dynamic equilibrium between the serum and the micellar milk phase make the distribution susceptible to certain physicochemical conditions and to technological treatments of milk resulting in fluctuations in pH and temperature and also sensitive to addition of calcium...... salts. The perturbation of calcium equilibria by these factors will affect the final properties of acid, calcium and rennet milk gels. By decreasing the pH from 6.0 to 5.2 (acid gels), the calcium equilibrium was significantly affected by temperature (4, 20, 30, 40 oC), and different combinations...

  3. Improved workability of injectable calcium sulfate bone cement by regulation of self-setting properties

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zonggang, E-mail: chenzg@sdu.edu.cn [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Liu, Huanye [Department of Orthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China); Liu, Xi [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Lian, Xiaojie [College of Mechanics, Taiyuan University of Technology, Taiyuan 030024 (China); Guo, Zhongwu [National Glycoengineering Research Center, Shandong University, Jinan 250100 (China); Jiang, Hong-Jiang [Wendeng Hospital of Traditional Chinese Orthopedics and Traumatology, Shandong 264400 (China); Cui, Fu-Zhai, E-mail: cuifz@mail.tsinghua.edu.cn [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2013-04-01

    Calcium sulfate hemihydrate (CSH) powder as an injectable bone cement was prepared by hydrothermal synthesis of calcium sulfate dihydrate (CSD). The prepared materials showed X-ray diffraction peaks corresponding to the CSH structure without any secondary phases, implying complete conversion from CSD phase to CSH phase. Thermogravimetric (TG) analyses showed the crystal water content of CSH was about 6.0% (wt.), which is near to the theoretic crystal water value of CSH. From scanning electron microscopy (SEM) micrographs, sheet crystal structure of CSD was observed to transform into rod-like crystal structure of CSH. Most interesting and important of all, CSD as setting accelerator was also introduced into CSH powder to regulate self-setting properties of injectable CSH paste, and thus the self-setting time of CSH paste can be regulated from near 30 min to less than 5 min by adding various amounts of setting accelerator. Because CSD is not only the reactant of preparing CSH but also the final solidified product of CSH, the setting accelerator has no significant effect on the other properties of materials, such as mechanical properties. In vitro biocompatibility and in vivo histology studies have demonstrated that the materials have good biocompatibility and good efficacy in bone regeneration. All these will further improve the workability of CSH in clinic applications. Highlights: ► Calcium sulfate hemihydrate (CSH) can be an injectable bone cement. ► CSH was produced by hydrothermal synthesis of calcium sulfate dihydrate (CSD). ► CSD was introduced into CSH powder to regulate self-setting properties of CSH. ► Setting accelerator has no significant effect on the other properties of materials. ► Injectable CSH has good biocompatibility and good efficacy in bone regeneration.

  4. Exopolysaccharides regulate calcium flow in cariogenic biofilms.

    Science.gov (United States)

    Astasov-Frauenhoffer, Monika; Varenganayil, Muth M; Decho, Alan W; Waltimo, Tuomas; Braissant, Olivier

    2017-01-01

    Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS) provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya's agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC) by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR) spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC). Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries.

  5. Exopolysaccharides regulate calcium flow in cariogenic biofilms.

    Directory of Open Access Journals (Sweden)

    Monika Astasov-Frauenhoffer

    Full Text Available Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya's agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC. Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries.

  6. Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins

    DEFF Research Database (Denmark)

    Hsu, Yu-Juei; Dimke, Henrik Anthony; Schoeber, Joost P H

    2010-01-01

    Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had...... higher urinary calcium excretion than female mice and their renal calcium transporters were expressed at a lower level. We also found that orchidectomized mice excreted less calcium in their urine than sham-operated control mice and that the hypocalciuria was normalized after testosterone replacement...... calcium transport. Thus, our study shows that gender differences in renal calcium handling are, in part, mediated by the inhibitory actions of androgens on TRPV5-mediated active renal calcium transport....

  7. A Closer look at calcium absorption and the benefits and risks of dietary versus supplemental calcium.

    Science.gov (United States)

    Booth, Anna; Camacho, Pauline

    2013-11-01

    To perform a thorough search of the literature on calcium research and specifically address the topic of calcium absorption. PubMed and Ovid were the main engines used for primary literature searches; textbooks, review articles, and book chapters are examples of the other sources used for supplemental information. Regarding calcium absorption, it seems apparent that the absorption efficiency of all calcium salts, regardless of solubility, is fairly equivalent and not significantly less than the absorption efficiency of dietary calcium. However, dietary calcium has been shown to have greater impact in bone building than supplemental calcium. This is likely due to improved absorption with meals and the tendency of people to intake smaller amounts more frequently, which is more ideal for the body's method of absorption. In addition, the cardiovascular risks of excessive calcium intake appear to be more closely related to calcium supplements than dietary calcium; this relationship continues to be controversial in the literature. We conclude that further studies are needed for direct comparison of supplemental and dietary calcium to fully establish if one is superior to the other with regard to improving bone density. We also propose further studies on the cardiovascular risk of long-term increased calcium intake and on physician estimates of patients' daily calcium intake to better pinpoint those patients who require calcium supplementation.

  8. Biomineralization of nanoscale single crystal hydroxyapatite

    Energy Technology Data Exchange (ETDEWEB)

    Omokanwaye, Tiffany [Catholic University of America, BONE/CRAB Lab, Department of Biomedical Engineering, Washington, DC 20064 (United States); Wilson, Otto C., E-mail: wilsono@cua.edu [Catholic University of America, BONE/CRAB Lab, Department of Biomedical Engineering, Washington, DC 20064 (United States); Gugssa, Ayelle; Anderson, Winston [Howard University, Department of Biology, Washington, DC (United States)

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague–Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5 nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54 nm and 0.23 nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. - Highlights: • Nanocrystalline particles were formed during in vivo implantation of crab shell using a rat model. • High resolution TEM revealed that nanoparticles were single crystals and less than 5 nm in size. • The relative distance between spots matches the expected values for hydroxyapatite.

  9. CCN3 and calcium signaling

    Directory of Open Access Journals (Sweden)

    Li Chang Long

    2003-08-01

    Full Text Available Abstract The CCN family of genes consists presently of six members in human (CCN1-6 also known as Cyr61 (Cystein rich 61, CTGF (Connective Tissue Growth Factor, NOV (Nephroblastoma Overexpressed gene, WISP-1, 2 and 3 (Wnt-1 Induced Secreted Proteins. Results obtained over the past decade have indicated that CCN proteins are matricellular proteins, which are involved in the regulation of various cellular functions, such as proliferation, differentiation, survival, adhesion and migration. The CCN proteins have recently emerged as regulatory factors involved in both internal and external cell signaling. CCN3 was reported to physically interact with fibulin-1C, integrins, Notch and S100A4. Considering that, the conformation and biological activity of these proteins are dependent upon calcium binding, we hypothesized that CCN3 might be involved in signaling pathways mediated by calcium ions. In this article, we review the data showing that CCN3 regulates the levels of intracellular calcium and discuss potential models that may account for the biological effects of CCN3.

  10. Kinetics of calcium sulfoaluminate formation from tricalcium aluminate, calcium sulfate and calcium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuerun, E-mail: xuerunli@163.com; Zhang, Yu; Shen, Xiaodong, E-mail: xdshen@njut.edu.cn; Wang, Qianqian; Pan, Zhigang

    2014-01-15

    The formation kinetics of tricalcium aluminate (C{sub 3}A) and calcium sulfate yielding calcium sulfoaluminate (C{sub 4}A{sub 3}$) and the decomposition kinetics of calcium sulfoaluminate were investigated by sintering a mixture of synthetic C{sub 3}A and gypsum. The quantitative analysis of the phase composition was performed by X-ray powder diffraction analysis using the Rietveld method. The results showed that the formation reaction 3Ca{sub 3}Al{sub 2}O{sub 6} + CaSO{sub 4} → Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 6CaO was the primary reaction < 1350 °C with and activation energy of 231 ± 42 kJ/mol; while the decomposition reaction 2Ca{sub 4}Al{sub 6}O{sub 12}(SO{sub 4}) + 10CaO → 6Ca{sub 3}Al{sub 2}O{sub 6} + 2SO{sub 2} ↑ + O{sub 2} ↑ primarily occurred beyond 1350 °C with an activation energy of 792 ± 64 kJ/mol. The optimal formation region for C{sub 4}A{sub 3}$ was from 1150 °C to 1350 °C and from 6 h to 1 h, which could provide useful information on the formation of C{sub 4}A{sub 3}$ containing clinkers. The Jander diffusion model was feasible for the formation and decomposition of calcium sulfoaluminate. Ca{sup 2+} and SO{sub 4}{sup 2−} were the diffusive species in both the formation and decomposition reactions. -- Highlights: •Formation and decomposition of calcium sulphoaluminate were studied. •Decomposition of calcium sulphoaluminate combined CaO and yielded C{sub 3}A. •Activation energy for formation was 231 ± 42 kJ/mol. •Activation energy for decomposition was 792 ± 64 kJ/mol. •Both the formation and decomposition were controlled by diffusion.

  11. Hydration Effects on the Stability of Calcium Carbonate Pre-Nucleation Species

    Directory of Open Access Journals (Sweden)

    Alejandro Burgos-Cara

    2017-07-01

    Full Text Available Recent experimental evidence and computer modeling have shown that the crystallization of a range of minerals does not necessarily follow classical models and theories. In several systems, liquid precursors, stable pre-nucleation clusters and amorphous phases precede the nucleation and growth of stable mineral phases. However, little is known on the effect of background ionic species on the formation and stability of pre-nucleation species formed in aqueous solutions. Here, we present a systematic study on the effect of a range of background ions on the crystallization of solid phases in the CaCO3-H2O system, which has been thoroughly studied due to its technical and mineralogical importance, and is known to undergo non-classical crystallization pathways. The induction time for the onset of calcium carbonate nucleation and effective critical supersaturation are systematically higher in the presence of background ions with decreasing ionic radii. We propose that the stabilization of water molecules in the pre-nucleation clusters by background ions can explain these results. The stabilization of solvation water hinders cluster dehydration, which is an essential step for precipitation. This hypothesis is corroborated by the observed correlation between parameters such as the macroscopic equilibrium constant for the formation of calcium/carbonate ion associates, the induction time, and the ionic radius of the background ions in the solution. Overall, these results provide new evidence supporting the hypothesis that pre-nucleation cluster dehydration is the rate-controlling step for calcium carbonate precipitation.

  12. Amorphous calcium carbonate precipitation by cellular biomineralization in mantle cell cultures of Pinctada fucata.

    Directory of Open Access Journals (Sweden)

    Liang Xiang

    Full Text Available 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.

  13. Manipulation of colloidal crystallization

    NARCIS (Netherlands)

    Vermolen, E.C.M.

    2008-01-01

    Colloidal particles (approximately a micrometer in diameter) that are dispersed in a fluid, behave thermodynamically similar to atoms and molecules: at low concentrations they form a fluid, while at high concentrations they can crystallize into a colloidal crystal to gain entropy. The analogy with

  14. Thermotropic Ionic Liquid Crystals

    OpenAIRE

    Sabine Laschat; Axenov, Kirill V

    2011-01-01

    The last five years’ achievements in the synthesis and investigation of thermotropic ionic liquid crystals are reviewed. The present review describes the mesomorphic properties displayed by organic, as well as metal-containing ionic mesogens. In addition, a short overview on the ionic polymer and self-assembled liquid crystals is given. Potential and actual applications of ionic mesogens are also discussed.

  15. Photonic crystal fibers

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Hansen, K P; Nielsen, M D

    2003-01-01

    Photonic crystal fibers having a complex microstructure in the transverse plane constitute a new and promising class of optical fibers. Such fibers can either guide light through total internal reflection or the photonic bandgap effect, In this paper, we review the different types and applications...... of photonic crystal fibers with particular emphasis on recent advances in the field....

  16. Crystals in the LHC

    CERN Multimedia

    Antonella Del Rosso

    2012-01-01

    Bent crystals can be used to deflect charged particle beams. Their use in high-energy accelerators has been investigated for almost 40 years. Recently, a bent crystal was irradiated for the first time in the HiRadMat facility with an extreme particle flux, which crystals would have to withstand in the LHC. The results were very encouraging and confirmed that this technology could play a major role in increasing the beam collimation performance in future upgrades of the machine.   UA9 bent crystal tested with a laser. Charged particles interacting with a bent crystal can be trapped in channelling states and deflected by the atomic planes of the crystal lattice (see box). The use of bent crystals for beam manipulation in particle accelerators is a concept that has been well-assessed. Over the last three decades, a large number of experimental findings have contributed to furthering our knowledge and improving our ability to control crystal-particle interactions. In modern hadron colliders, su...

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

    Science.gov (United States)

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

    2015-04-01

    The formation of calcium carbonate (CaCO3) in aqueous supersaturated solutions has been intensively studied over the past decades, because of its significance for a number of processes of industrial and environmental interest. In the oil and gas production industry the deposition of calcium carbonate affects adversely the productivity of the wells. Calcium carbonate scale deposits formation causes serious problems in water desalination, CO2 sequestration in subsoil wells, in geothermal systems and in heat exchangers because of the low thermal coefficient of the salt. Amelioration of the operational conditions is possible only when the mechanisms underlying nucleation and crystal growth of calcium carbonate in the aqueous fluids is clarified. Given the fact that in oil production processes water miscible and immiscible hydrocarbons are present the changes of the dielectric constant of the fluid phase has serious impact in the kinetics of calcium carbonate precipitation, which remains largely unknown. The problem becomes even more complicated if polymorphism exhibited by calcium carbonate is also taken into consideration. In the present work, the stability of aqueous solutions supersaturated with respect to all calcium carbonate polymorphs and the subsequent kinetics of calcium carbonate precipitation were measured. The measurements included aqueous solutions and solutions in the presence of water miscible (ethylene glycol, MEG) and water immiscible organics (n-dodecane). All measurements were done at conditions of sustained supersaturation using the glass/ Ag/AgCl combination electrode as a probe of the precipitation and pH as the master variable for the addition of titrant solutions with appropriate concentration needed to maintenance the solution supersaturation. Initially, the metastable zone width was determined from measurements of the effect of the solution supersaturation on the induction time preceding the onset of precipitation at free-drift conditions. The

  18. Optically Anomalous Crystals

    CERN Document Server

    Shtukenberg, Alexander; Kahr, Bart

    2007-01-01

    Optical anomalies in crystals are puzzles that collectively constituted the greatest unsolved problems in crystallography in the 19th Century. The most common anomaly is a discrepancy between a crystal’s symmetry as determined by its shape or by X-ray analysis, and that determined by monitoring the polarization state of traversing light. These discrepancies were perceived as a great impediment to the development of the sciences of crystals on the basis of Curie’s Symmetry Principle, the grand organizing idea in the physical sciences to emerge in the latter half of the 19th Century. Optically Anomalous Crystals begins with an historical introduction covering the contributions of Brewster, Biot, Mallard, Brauns, Tamman, and many other distinguished crystallographers. From this follows a tutorial in crystal optics. Further chapters discuss the two main mechanisms of optical dissymmetry: 1. the piezo-optic effect, and 2. the kinetic ordering of atoms. The text then tackles complex, inhomogeneous crystals, and...

  19. Progress on photonic crystals

    CERN Document Server

    Lecoq, P; Gundacker, S; Hillemanns, H; Jarron, P; Knapitsch, A; Leclercq, J L; Letartre, X; Meyer, T; Pauwels, K; Powolny, F; Seassal, C

    2010-01-01

    The renewal of interest for Time of Flight Positron Emission Tomography (TOF PET) has highlighted the need for increasing the light output of scintillating crystals and in particular for improving the light extraction from materials with a high index of refraction. One possible solution to overcome the problem of total internal reflection and light losses resulting from multiple bouncing within the crystal is to improve the light extraction efficiency at the crystal/photodetector interface by means of photonic crystals, i.e. media with a periodic modulation of the dielectric constant at the wavelength scale. After a short reminder of the underlying principles this contribution proposes to present the very encouraging results we have recently obtained on LYSO pixels and the perspectives on other crystals such as BGO, LuYAP and LuAG. These results confirm the impressive predictions from our previously published Monte Carlo simulations. A detailed description of the sample preparation procedure is given as well ...

  20. Identification of a macromolecular crystal growth inhibitor in human urine as osteopontin

    DEFF Research Database (Denmark)

    Sørensen, Steen; Justesen, S J; Johnsen, A H

    1995-01-01

    Macromolecules occurring in human urine inhibit the growth and/or aggregation of calcium oxalate crystals and may prevent the formation of kidney stones. Attention has focused particularly on proteins, as these seem to be most responsible for the inhibitory activity; three proteins, nephrocalcin...

  1. The Role of Calcium in Osteoporosis

    Science.gov (United States)

    Arnaud, C. D.; Sanchez, S. D.

    1991-01-01

    Calcium requirements may vary throughout the lifespan. During the growth years and up to age 25 to 30, it is important to maximize dietary intake of calcium to maintain positive calcium balance and achieve peak bone mass, thereby possibly decreasing the risk of fracture when bone is subsequently lost. Calcium intake need not be greater than 800 mg/day during the relatively short period of time between the end of bone building and the onset of bone loss (30 to 40 years). Starting at age 40 to 50, both men and women lose bone slowly, but women lose bone more rapidly around the menopause and for about 10 years after. Intestinal calcium absorption and the ability to adapt to low calcium diets are impaired in many postmenopausal women and elderly persons owing to a suspected functional or absolute decrease in the ability of the kidney to produce 1,25(OH)2D2. The bones then become more and more a source of calcium to maintain critical extracellular fluid calcium levels. Excessive dietary intake of protein and fiber may induce significant negative calcium balance and thus increase dietary calcium requirements. Generally, the strongest risk factors for osteoporosis are uncontrollable (e.g., sex, age, and race) or less controllable (e.g., disease and medications). However, several factors such as diet, physical activity, cigarette smoking, and alcohol use are lifestyle related and can be modified to help reduce the risk of osteoporosis.

  2. Assessment of calcium intake by adolescents

    Directory of Open Access Journals (Sweden)

    Cristiane Franco de Oliveira

    2014-06-01

    Full Text Available OBJECTIVE: To evaluate the daily calcium intake of adolescents in schools from Chapecó, Santa Catarina, Southern Brazil, to check if calcium intake is in accordance with the Dietary Reference Intakes (DRI, and to investigate variables associated with daily calcium intake.METHODS: Cross-sectional study approved by the Institutional Review Board and developed in 2010. Students of the 8th grade completed questionnaires with personal data and questions about the calcium-rich foods intake frequency. In order to compare students with adequate (1300mg or inadequate intake of calcium/day (<1300mg, parametric and nonparametric tests were used.RESULTS: A total of 214 students with a mean age of 14.3±1.0 years were enrolled. The median daily calcium intake was 540mg (interquartile range - IQ: 312-829mg and only 25 students (11.7% had calcium intake within the recommendations of the DRI for age. Soft drink consumption ≥3 times/week was associated with a lower intake of calcium.CONCLUSIONS: Few students ingested adequate levels of calcium for the age group. It is necessary to develop a program to encourage a greater intake of calcium-rich foods in adolescence.

  3. The Risks and Benefits of Calcium Supplementation

    Directory of Open Access Journals (Sweden)

    Chan Soo Shin

    2015-03-01

    Full Text Available The association between calcium supplementation and adverse cardiovascular events has recently become a topic of debate due to the publication of two epidemiological studies and one meta-analysis of randomized controlled clinical trials. The reports indicate that there is a significant increase in adverse cardiovascular events following supplementation with calcium; however, a number of experts have raised several issues with these reports such as inconsistencies in attempts to reproduce the findings in other populations and questions concerning the validity of the data due to low compliance, biases in case ascertainment, and/or a lack of adjustment. Additionally, the Auckland Calcium Study, the Women's Health Initiative, and many other studies included in the meta-analysis obtained data from calcium-replete subjects and it is not clear whether the same risk profile would be observed in populations with low calcium intakes. Dietary calcium intake varies widely throughout the world and it is especially low in East Asia, although the risk of cardiovascular events is less prominent in this region. Therefore, clarification is necessary regarding the occurrence of adverse cardiovascular events following calcium supplementation and whether this relationship can be generalized to populations with low calcium intakes. Additionally, the skeletal benefits from calcium supplementation are greater in subjects with low calcium intakes and, therefore, the risk-benefit ratio of calcium supplementation is likely to differ based on the dietary calcium intake and risks of osteoporosis and cardiovascular diseases of various populations. Further studies investigating the risk-benefit profiles of calcium supplementation in various populations are required to develop population-specific guidelines for individuals of different genders, ages, ethnicities, and risk profiles around the world.

  4. Crystallization phenomena of isotactic polystyrene

    NARCIS (Netherlands)

    Lemstra, Peter Jan

    1975-01-01

    In this thesis the crystallization behavior of isotactic polystyrene has been described. The kinetics of the crystallization process and the crystalline structure were studied both for crystallization in the bulk and from dilute solutions. ... Zie Summary

  5. The co-effect of organic matrix from carp otolith and microenvironment on calcium carbonate mineralization.

    Science.gov (United States)

    Ren, Dongni; Feng, Qingling; Bourrat, Xavier

    2013-08-01

    In vitro mineralization experiment is an effective way to study the effect of organic matrix on calcium carbonate crystallization, and to reveal the relationship between organic matrix and inorganic crystal in natural biominerals. In natural biominerals, organic matrix plays an important role in crystal formation and stability, together with microenvironment changes, they can affect crystal polymorph, morphology, density, size, orientation etc. In this work, we systematically studied the effects of different organic matrices in fish otoliths, the organic matrix concentration changes, as well as the co-effect of organic matrices with temperature, pH value and Mg ion changes in the in vitro CaCO3 mineralization experiments. The organic matrix and concentration change experiments prove that water soluble matrix (WSM) plays an important role in crystal form transition. It can induce CaCO3 crystals with same crystal polymorph as the otolith from which organic matrix was extracted. The temperature change experiment proves that CaCO3 has a tendency to form calcite, vaterite, and then aragonite in priority as temperature goes up. Under different temperature, WSM from lapillus/asteriscus still has the effect to mediate different CaCO3 crystals. The pH change experiment shows that, near the neutral environment, as pH value goes up, calcites have a tendency to form crystal aggregates with more faces exposed, the organic matrix still keeps crystal mediation effect. The Mg(2+) experiment shows that, Mg ion can promote aragonite formation, together with lapillus organic matrix, aragonites with different shapes are formed. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Formation of calcium phosphates by vapour diffusion in highly concentrated ionic micro-droplets

    Energy Technology Data Exchange (ETDEWEB)

    Iafisco, M. [Alma Mater Studiorum Universita di Bologna, Dipartimento di Chimica ' ' G. Ciamician' ' , Via Selmi 2, 40126 Bologna (Italy); Universita del Piemonte Orientale, Dipartimento di Scienze Mediche, Via Solaroli 4, 28100 Novara (Italy); Delgado-Lopez, J.M.; Gomez-Morales, J.; Hernandez-Hernandez, M.A.; Rodriguez-Ruiz, I. [Laboratorio de Estudios Cristalograficos, IACT CSIC-UGR, Edificio Lopez Neyra, Avenida del Conocimiento, s/n 18100 Armilla (Spain); Roveri, N. [Alma Mater Studiorum Universita di Bologna, Dipartimento di Chimica ' ' G. Ciamician' ' , Via Selmi 2, 40126 Bologna (Italy)

    2011-08-15

    In this work we have used the sitting drop vapour diffusion technique, employing the ''crystallization mushroom '' to analyze the evolution of calcium phosphate crystallization in micro-droplets containing high initial concentrations of Ca{sup 2+} and HPO{sub 4}{sup 2-}. The decomposition of NH{sub 4}HCO{sub 3} solution produces vapours of NH{sub 3} and CO{sub 2} which diffuse through the droplets containing an aqueous solution of Ca(CH{sub 3}COO){sub 2} and (NH{sub 4}){sub 2}HPO{sub 4}. The result is the increase of pH by means of the diffusion of NH{sub 3} gas and the doping of the calcium phosphate with CO{sub 3}{sup 2-} ions by means of the diffusion of CO{sub 2} gas. The pH of the crystallization process is monitored and the precipitates at different times are characterized by XRD, FTIR, TGA, SEM and TEM techniques. The slow increase of pH and the high concentration of Ca{sup 2+} and HPO{sub 4}{sup 2-} in the droplets induce the crystallization of three calcium phosphate phases: dicalcium phosphate dihydrate (DCPD, brushite), octacalcium phosphate (OCP) and carbonate-hydroxyapatite (HA). The amount of HA nanocrystals with needle-like morphology and dimensions of about 100 nm, closely resembling the inorganic phase of bones, gradually increases, with the precipitation time up to 7 days, whereas the amount of DCPD, growing along the b axis, increases up to 3 days. Then, DCDP crystals start to hydrolyze yielding OCP nanoribbons and HA nanocrystals. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Diagenetic Crystal Growth in the Murray Formation, Gale Crater, Mars

    Science.gov (United States)

    Kah, L. C.; Kronyak, R. E.; Ming, D. W.; Grotzinger, J. P.; Schieber, J.; Sumner, D. Y.; Edgett, K. S.

    2015-01-01

    The Pahrump region (Gale Crater, Mars) marks a critical transition between sedimentary environments dominated by alluvial-to-fluvial materials associated with the Gale crater rim, and depositional environments fundamentally linked to the crater's central mound, Mount Sharp. At Pahrump, the Murray formation consists of an approximately 14-meter thick succession dominated by massive to finely laminated mudstone with occasional interbeds of cross-bedded sandstone, and is best interpreted as a dominantly lacustrine environment containing tongues of prograding fluvial material. Murray formation mudstones contain abundant evidence for early diagenetic mineral precipitation and its subsequent removal by later diagenetic processes. Lenticular mineral growth is particularly common within lacustrine mudstone deposits at the Pahrump locality. High-resolution MAHLI images taken by the Curiosity rover permit detailed morphological and spatial analysis of these features. Millimeter-scale lenticular features occur in massive to well-laminated mudstone lithologies and are interpreted as pseudomorphs after calcium sulfate. The distribution and orientation of lenticular features suggests deposition at or near the sediment-water (or sediment-air) interface. Retention of chemical signals similar to host rock suggests that original precipitation was likely poikilotopic, incorporating substantial amounts of the primary matrix. Although poikilotopic crystal growth is common in burial environments, it also occurs during early diagenetic crystal growth within unlithified sediment where high rates of crystal growth are common. Loss of original calcium sulfate mineralogy suggests dissolution by mildly acidic, later-diagenetic fluids. As with lenticular voids observed at Meridiani by the Opportunity Rover, these features indicate that calcium sulfate deposition may have been widespread on early Mars; dissolution of depositional and early diagenetic minerals is a likely source for both calcium

  8. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    OpenAIRE

    Eder, Anja; Bading, Hilmar

    2007-01-01

    Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nuc...

  9. A comparison of leaf crystal macropatterns in the two sister genera Piper and Peperomia (Piperaceae).

    Science.gov (United States)

    Horner, Harry T; Wanke, Stefan; Samain, Marie-Stéphanie

    2012-06-01

    This is the first large-scale study comparing leaf crystal macropatterns of the species-rich sister genera Piper and Peperomia. It focuses on identifying types of calcium oxalate crystals and their macropatterns in leaves of both genera. The Piper results are placed in a phylogenetic context to show evolutionary patterns. This information will expand knowledge about crystals and provide specific examples to help study their form and function. One example is the first-time observation of Piper crystal sand tumbling in chlorenchyma vacuoles. Herbarium and fresh leaves were cleared of cytoplasmic content and examined with polarizing microscopy to identify types of crystals and their macropatterns. Selected hydrated herbarium and fresh leaf punches were processed for scanning electron microscopy and x-ray elemental analysis. Vibratome sections of living Piper and Peperomia leaves were observed for anatomical features and crystal movement. Both genera have different leaf anatomies. Piper displays four crystal types in chlorenchyma-crystal sand, raphides, styloids, and druses, whereas Peperomia displays three types-druses, raphides, and prisms. Because of different leaf anatomies and crystal types between the genera, macropatterns are completely different. Crystal macropattern evolution in both is characterized by increasing complexity, and both may use their crystals for light gathering and reflection for efficient photosynthesis under low-intensity light environments. Both genera have different leaf anatomies, types of crystals and crystal macropatterns. Based on Piper crystals associated with photosynthetic tissues and low-intensity light, further study of their function and association with surrounding chloroplasts is warranted, especially active crystal movement.

  10. Polymorphism of felodipine co-crystals with 4,4'-bipyridine

    DEFF Research Database (Denmark)

    Surov, Artem Olegovich; Solanko, Katarzyna A.; Bond, Andrew

    2014-01-01

    The calcium-channel blocking agent felodipine (Fel) forms co-crystals with 4,4′-bipyridine (BP) with 1:1 and 2:1 molar ratios. The [Fel + BP] (1:1) co-crystal exists in two polymorphic forms. Differential scanning calorimetry and solution calorimetry show that form I of the [Fel + BP] (1:1) co-cr...... that the packing energy gain originates from only weak van der Waals interactions. Analysis of Hirshfeld surfaces of the felodipine molecule shows a similar distribution of intermolecular contacts in the co-crystals and pure felodipine....

  11. Calcium gluconate supplementation is effective to balance calcium homeostasis in patients with gastrectomy.

    Science.gov (United States)

    Krause, M; Keller, J; Beil, B; van Driel, I; Zustin, J; Barvencik, F; Schinke, T; Amling, M

    2015-03-01

    We demonstrate histological evidence for hyperparathyroidism in patients with gastrectomy. This is, at least in part, explained by impaired calcium absorption, resulting in mineralization defects and secondary hyperparathyroidism. Additionally, we demonstrate improved bone mineralization in patients with gastrectomy after gluconate therapy and showed the effectiveness of calcium gluconate over carbonate to balance impaired calcium hemostasis in mice. Gastrectomy and hypochlorhydria due to long-term proton pump inhibitor therapy are associated with increased fracture risk because of intestinal calcium malabsorption. Hence, our objectives were to histologically investigate bone metabolism in patients with gastrectomy and to analyze the impact of calcium gluconate supplementation on skeletal integrity in the setting of impaired gastric acidification. Undecalcified bone biopsies of 26 gastrectomized individuals were histologically analyzed. In the clinical setting, we retrospectively identified 5 gastrectomized patients with sufficient vitamin D level, who were additionally supplemented with calcium gluconate and had a real bone mineral density (aBMD) follow-up assessments. A mouse model of achlorhydria (ATP4b-/-) was used to compare the effect of calcium gluconate and calcium carbonate supplementation on bone metabolism. Biopsies from gastrectomized individuals showed significantly increased osteoid, osteoclast, and osteoblast indices and fibroosteoclasia (p < 0.05) as well as impaired calcium distribution in mineralized bone matrix compared to healthy controls. Five gastrectomized patients with sufficient vitamin D level demonstrated a significant increase in aBMD after a treatment with calcium gluconate alone for at least 6 months (p < 0.05). Calcium gluconate was superior to calcium carbonate in maintaining calcium metabolism in a mouse model of achlorhydria. Gastrectomy is associated with severe osteomalacia, marrow fibrosis, and impaired calcium distribution

  12. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    Directory of Open Access Journals (Sweden)

    Bading Hilmar

    2007-07-01

    Full Text Available Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.

  13. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    Science.gov (United States)

    Eder, Anja; Bading, Hilmar

    2007-01-01

    Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events. PMID:17663775

  14. Elemental Content of Calcium Oxalate Stones from a Canine Model of Urinary Stone Disease.

    Directory of Open Access Journals (Sweden)

    David W Killilea

    Full Text Available One of the most common types of urinary stones formed in humans and some other mammals is composed of calcium oxalate in ordered hydrated crystals. Many studies have reported a range of metals other than calcium in human stones, but few have looked at stones from animal models such as the dog. Therefore, we determined the elemental profile of canine calcium oxalate urinary stones and compared it to reported values from human stones. The content of 19 elements spanning 7-orders of magnitude was quantified in calcium oxalate stones from 53 dogs. The elemental profile of the canine stones was highly overlapping with human stones, indicating similar inorganic composition. Correlation and cluster analysis was then performed on the elemental profile from canine stones to evaluate associations between the elements and test for potential subgrouping based on elemental content. No correlations were observed with the most abundant metal calcium. However, magnesium and sulfur content correlated with the mineral hydration form, while phosphorous and zinc content correlated with the neuter status of the dog. Inter-elemental correlation analysis indicated strong associations between barium, phosphorous, and zinc content. Additionally, cluster analysis revealed subgroups within the stones that were also based primarily on barium, phosphorous, and zinc. These data support the use of the dog as a model to study the effects of trace metal homeostasis in urinary stone disease.

  15. Calcium phosphate scaling during wastewater desalination on oligoamide surfaces mimicking reverse osmosis and nanofiltration membranes.

    Science.gov (United States)

    Rathinam, Karthik; Oren, Yoram; Petry, Winfried; Schwahn, Dietmar; Kasher, Roni

    2018-01-01

    Desalinated domestic wastewater is an indispensable water resource in arid regions; however, its recovery can be limited by calcium phosphate scaling and fouling of the membrane. Here we investigated calcium phosphate mineralization on oligoamide surfaces that mimics reverse osmosis (RO) and nanofiltration (NF) membrane surfaces. We used a solution that simulates desalination of secondary treated domestic wastewater effluents for calcium phosphate mineralization experiments with oligoamide-coated gold surfaces. Attenuated total reflection-Fourier transform infrared spectroscopy and energy dispersive spectrometry showed that calcium phosphate and carbonate precipitated on RO mimetic surfaces. The rate of precipitation on oligoamide sensors was monitored by a quartz crystal microbalance, showing that scaling was more intense on the RO than the NF mimetic surface and that excessive carboxyl functional groups on both surfaces promoted scaling. Filtration experiments of similar solutions with commercial membranes showed that scaling was more intense on the RO membranes than on the NF membranes, which supported the results obtained with the oligoamide model surfaces. The results of this study can be implemented in developing RO and NF membranes to prevent calcium phosphate scaling and consequently lower water-treatment costs of domestic wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Induced calcium carbonate precipitation using Bacillus species.

    Science.gov (United States)

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

    2016-12-01

    Microbially induced calcium carbonate precipitation is an emerging process for the production of self-healing concrete. This study was aimed to investigate the effects and optimum conditions on calcium carbonate biosynthesis. Bacillus licheniformis, Bacillus sphaericus, yeast extract, urea, calcium chloride and aeration were found to be the most significant factors affecting the biomineralization of calcium carbonate. It was noticed that the morphology of microbial calcium carbonate was mainly affected by the genera of bacteria (cell surface properties), the viscosity of the media and the type of electron acceptors (Ca2+). The maximum calcium carbonate concentration of 33.78 g/L was achieved at the optimum conditions This value is the highest concentration reported in the literature.

  17. Calcium excretion in feces of ungulates.

    Science.gov (United States)

    Schryver, H F; Foose, T J; Williams, J; Hintz, H F

    1983-01-01

    1. Fecal excretion of calcium was examined in 122 individual ungulates representing 7 species of Equidae, 3 species of Tapiridae, 3 species of Rhinocerotidae, 2 species of Elephantidae, 2 species of Hippopotamidae, 12 species of Bovidae, 2 species of Cervidae, 3 species of Camellidae and 1 species of Giraffidae. 2. Animals were fed timothy hay, a low calcium diet or alfalfa hay, a high calcium diet. 3. In a few cases oat straw or prairie hay was used instead of timothy hay. 4. Samples of feces were obtained from individuals daily for 4 days following a 20 day dietary equilibration period. 5. Feces of equids, tapirs, rhinoceros and elephants had a lower calcium concentration and a lower Ca/P ratio than feces of ruminants when the animals were fed diets of equivalent calcium content. 6. The findings suggest that the non-ruminant ungulate equids, tapirs, rhinoceros and elephants absorb a larger proportion of dietary calcium than ruminants do.

  18. Binding of calcium and carbonate to polyacrylates.

    Science.gov (United States)

    Tribello, Gareth A; Liew, CheeChin; Parrinello, Michele

    2009-05-21

    Polyacrylate molecules can be used to slow the growth of calcium carbonate. However, little is known about the mechanism by which the molecules impede the growth rate. A recent computational study (Bulo et al. Macromolecules 2007, 40, 3437) used metadynamics to investigate the binding of calcium to polyacrylate chains and has thrown some light on the coiling and precipitation of these polymers. We extend these simulations to examine the binding of calcium and carbonate to polyacrylate chains. We show that calcium complexed with both carbonate and polyacrylate is a very stable species. The free energies of calcium-carbonate-polyacrylate complexes, with different polymer configurations, are calculated, and differences in the free energy of the binding of carbonate are shown to be due to differences in the amount of steric hindrance about the calcium, which prevents the approach of the carbonate ion.

  19. WAYS TO CORRECT CALCIUM DEFFICIT AMONG CHILDREN

    Directory of Open Access Journals (Sweden)

    N.I. Taibulatov

    2007-01-01

    Full Text Available The article is dedicated to the urgent issue of the pediatrics — calcium deficit among children. The authors provide modern data on the scheme of the normal calcium exchange in the human body. They also review the main diseases related to the disorders of the pho sphorocalcic metabolism, requiring prompt prevention and treatment by calcium based medications. The researchers stress the diseases of the musculoskeletal system, as insufficient calcium, phosphorus and vitamins supply of the child's body chiefly effects the state of the skeletal and muscular tissue. They give recommendations how to use the vitamin and mineral complex to correct calcium deficit.Key words: calcium deficit, diseases of the musculoskeletal system, vitamin and mineral complex, children.

  20. Altered calcium signaling in cancer cells.

    Science.gov (United States)

    Stewart, Teneale A; Yapa, Kunsala T D S; Monteith, Gregory R

    2015-10-01

    It is the nature of the calcium signal, as determined by the coordinated activity of a suite of calcium channels, pumps, exchangers and binding proteins that ultimately guides a cell's fate. Deregulation of the calcium signal is often deleterious and has been linked to each of the 'cancer hallmarks'. Despite this, we do not yet have a full understanding of the remodeling of the calcium signal associated with cancer. Such an understanding could aid in guiding the development of therapies specifically targeting altered calcium signaling in cancer cells during tumorigenic progression. Findings from some of the studies that have assessed the remodeling of the calcium signal associated with tumorigenesis and/or processes important in invasion and metastasis are presented in this review. The potential of new methodologies is also discussed. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers. Copyright © 2014 Elsevier B.V. All rights reserved.